U.S. patent application number 17/748242 was filed with the patent office on 2022-09-01 for electrolyte for a solid-state battery.
The applicant listed for this patent is CORNING INCORPORATED. Invention is credited to Michael Edward Badding, Jacqueline Leslie Brown, Jennifer Anella Heine, Thomas Dale Ketcham, Gary Edward Merz, Eric Lee Miller, Zhen Song, Cameron Wayne Tanner, Conor James Walsh.
Application Number | 20220278364 17/748242 |
Document ID | / |
Family ID | |
Filed Date | 2022-09-01 |
United States Patent
Application |
20220278364 |
Kind Code |
A1 |
Badding; Michael Edward ; et
al. |
September 1, 2022 |
ELECTROLYTE FOR A SOLID-STATE BATTERY
Abstract
Electrolyte for a solid-state battery includes a body having
grains of inorganic material sintered to one another, where the
grains include lithium. The body is thin, has little porosity by
volume, and has high ionic conductivity.
Inventors: |
Badding; Michael Edward;
(Campbell, NY) ; Brown; Jacqueline Leslie;
(Lindley, NY) ; Heine; Jennifer Anella; (Belleair
Bluffs, FL) ; Ketcham; Thomas Dale; (Horseheads,
NY) ; Merz; Gary Edward; (Rochester, NY) ;
Miller; Eric Lee; (Corning, NY) ; Song; Zhen;
(Painted Post, NY) ; Tanner; Cameron Wayne;
(Horseheads, NY) ; Walsh; Conor James; (Campbell,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CORNING INCORPORATED |
Corning |
NY |
US |
|
|
Appl. No.: |
17/748242 |
Filed: |
May 19, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16534573 |
Aug 7, 2019 |
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17748242 |
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16295673 |
Mar 7, 2019 |
10581115 |
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16534573 |
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PCT/US2017/067376 |
Dec 19, 2017 |
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16295673 |
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62439613 |
Dec 28, 2016 |
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62470550 |
Mar 13, 2017 |
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62439609 |
Dec 28, 2016 |
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62526806 |
Jun 29, 2017 |
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62439598 |
Dec 28, 2016 |
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62483726 |
Apr 10, 2017 |
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62484106 |
Apr 11, 2017 |
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62556712 |
Sep 11, 2017 |
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62437157 |
Dec 21, 2016 |
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International
Class: |
H01M 10/0562 20060101
H01M010/0562; H01M 4/04 20060101 H01M004/04; C04B 35/622 20060101
C04B035/622; B28B 1/30 20060101 B28B001/30; H01M 4/1391 20060101
H01M004/1391; H01M 4/131 20060101 H01M004/131; H01M 4/505 20060101
H01M004/505; G02B 6/122 20060101 G02B006/122; H01M 10/0525 20060101
H01M010/0525 |
Claims
1. A sheet of material configured for a solid-state battery,
comprising: a body comprising ceramic grains sintered to one
another, wherein the grains comprise lithium, lanthanum, zirconium,
and oxygen, and wherein greater than 95% of the body by weight
consists of cubic lithium garnet crystals; wherein thickness of the
body, between first and second major surfaces thereof, is in a
range from 3 .mu.m to 100 .mu.m, and wherein the body has a width
of 5 mm or greater; wherein the body is flattenable without
fracturing as determined by pressing the body between rigid
parallel surfaces at 23.degree. C. such that the body overlays or
is within a distance of 0.05 mm of a flat plane; and wherein the
grains sintered to one another have an average grain size of 5
.mu.m or less, and wherein the body has ionic conductivity greater
than 1.times.10.sup.-4 S/cm.
2. The sheet of claim 1, wherein the body has closed porosity.
3. The sheet of claim 1, wherein the body has less than 10%
porosity by volume.
4. The sheet of claim 1, wherein the grains further comprise
tantalum, and wherein the body has ionic conductivity greater than
2.times.10.sup.-4 S/cm.
5. The sheet of claim 4, wherein the grains further comprise
aluminum.
6. The sheet of claim 1, wherein the body has a length of at least
10 m.
7. A roll of the sheet of claim 6 wound on a spool.
8. A sheet of material configured for a solid-state battery,
comprising: a body comprising ceramic grains sintered to one
another, wherein the grains comprise lithium, and wherein greater
than 95% of the body by weight consists of cubic lithium garnet
crystals; wherein thickness of the body, between first and second
major surfaces thereof, is in a range from 3 .mu.m to 50 .mu.m, and
wherein the body has a width of 5 mm or greater; wherein the body
has a length of 1 m or greater; wherein fewer than 10 pin holes of
a cross-sectional area of at least a square micrometer pass through
the body, per square millimeter of surface on average; and wherein
the grains sintered to one another have an average grain size of 5
.mu.m or less, and wherein the body has ionic conductivity greater
than 1.times.10.sup.-4 S/cm.
9. The sheet of claim 8, wherein the body has a length of at least
10 m.
10. A roll of the sheet of claim 9 wound on a spool.
11. The sheet of claim 8, wherein the body has closed porosity.
12. The sheet of claim 11, wherein the body has less than 10%
porosity by volume.
13. The sheet of claim 12, wherein the grains further comprise
lanthanum, zirconium, and oxygen.
14. A sheet of material configured fora solid-state battery,
comprising: a body comprising ceramic grains sintered to one
another, wherein the grains comprise lithium, lanthanum, zirconium,
and oxygen, and wherein greater than 95% of the body by weight
consists of cubic lithium garnet crystals; wherein thickness of the
body, between first and second major surfaces thereof, is in a
range from 3 .mu.m to 50 .mu.m, and wherein the body has a width of
5 mm or greater; wherein fewer than 10 pin holes of a
cross-sectional area of at least a square micrometer pass through
the body, per square millimeter of surface on average; wherein the
body is flattenable without fracturing as determined by pressing
the body between rigid parallel surfaces at 23.degree. C. such that
the body overlays or is within a distance of 0.05 mm of a flat
plane; and wherein the grains sintered to one another have an
average grain size of 5 .mu.m or less, and wherein the body has
ionic conductivity greater than 1.times.10.sup.-4 S/cm.
15. The sheet of claim 14, wherein the body has closed
porosity.
16. The sheet of claim 14, wherein the body has less than 10%
porosity by volume.
17. The sheet of claim 14, wherein the grains further comprise
tantalum, and wherein the body has ionic conductivity greater than
2.times.10.sup.-4 S/cm.
18. The sheet of claim 14, wherein the grains further comprise
aluminum.
19. The sheet of claim 14, wherein the body has a length of at
least 10 m.
20. A roll of the sheet of claim 19 wound on a spool.
Description
PRIORITY
[0001] This application is a continuation of U.S. application Ser.
No. 16/534,573 filed Aug. 7, 2019, which is a continuation of U.S.
application Ser. No. 16/295,673 filed Mar. 7, 2019, which issued as
U.S. Pat. No. 10,581,115 and is a continuation of International
Application No. PCT/US2017/067376 filed Dec. 19, 2017, which claims
the priority benefit of U.S. Application Nos. 62/556,712 filed Sep.
11, 2017, 62/526,806 filed Jun. 29, 2017, 62/484,106 filed Apr. 11,
2017, 62/483,726 filed Apr. 10, 2017, 62/470,550 filed Mar. 13,
2017, 62/439,609 filed Dec. 28, 2016, 62/439,598 filed Dec. 28,
2016, 62/439,613 filed Dec. 28, 2016, and 62/437,157 filed Dec. 21,
2016, each of which is incorporated by reference herein in its
entirety.
BACKGROUND
[0002] The disclosure relates generally to processes for sintering,
such as sintering green tape including polycrystalline ceramic
grains or other inorganic particles, bound in a binder, as well as
continuous and discrete sintered articles, such as ceramic sheets,
tapes or ceramic pieces made from such processes. The disclosure
relates articles, such as thin sheets, tapes, ribbons or pieces of
ceramic or other inorganic materials that have many potential uses,
such as serving as waveguides, when the ceramic is transmissive to
light, serving as substrates that may be coated or laminated, and
integrated in batteries and other components, or used as or joined
with a substrate such as to act as a dielectric in an electronics
package (e.g., LED package), or other applications. Various
material properties, particularly of ceramic materials, such as
high resistivity, low reactivity, low coefficient of thermal
expansion, etc. make such articles particularly useful in a wide
variety of applications.
SUMMARY
[0003] Some aspects of the present disclosure relate to a tape
separation system for sintering preparation. The tape separation
system includes a source of tape material comprising a green tape
and a carrier web supporting the green tape. The green tape
comprising grains of inorganic material in a binder. The tape
separation system further includes a peeler for directing the
carrier web in a rewind direction and directing the green tape in a
downstream processing direction that differs from the rewind
direction, and a vacuum drum positioned and configured to receive
the tape material from the source and convey the tape material to
the peeler. The vacuum drum comprises holes for applying suction to
the carrier web to facilitate tensioning the carrier web, and
tension, in force per cross-sectional area, in the carrier web is
greater than tension in the green tape as the tape material is
conveyed from the vacuum drum to the peeler, thereby mitigating
deformation of the green tape during separation of the green tape
from the carrier web.
[0004] Other aspects of the present disclosure relate to a system
for processing tape for sintering preparation. The system includes
a tape comprising a green portion of the tape, the green portion
having grains of an inorganic material in an organic binder; and a
binder burnout station comprising an active heater. The tape
advances through the binder burnout station such that the binder
burnout station receives the green portion of the tape and chars or
burns the organic binder as the green portion of the tape
interfaces with heat from the heater, thereby forming a second
portion of the tape prepared for sintering the inorganic material
of the tape. In some embodiments, at an instant, the tape
simultaneously extends to, through, and from the binder burnout
station such that, at the instant, the tape includes the green
portion continuously connected to the second portion, such as where
the binder burnout station chars or burns at least most of the
organic binder, in terms of weight, from the green portion of the
tape without substantially sintering the grains of the inorganic
material. In some embodiments, system for processing tape for
sintering preparation further includes an ultra-low tension dancer
that includes light-weight, low-inertia rollers to redirect the
tape without exerting significant tension such that tension in the
second portion of the tape is less than 500 grams-force per
mm.sup.2 of cross section, thereby reducing chances of fracture of
the second portion of the tape and facilitating long continuous
lengths of the tape for sintering. In some embodiments, system for
processing tape for sintering preparation blows and/or draws gas
over the tape as the tape advances through the binder burnout
station, and the binder burnout station heats the tape above a
temperature at which the organic binder would ignite without the
gas blown and/or drawn over the tape, whereby the organic binder
chars or burns but the tape does not catch fire.
[0005] Additional aspects of the present disclosure relate to a
manufacturing line comprising the above system for processing tape,
where the binder burnout station is a first station and the
manufacturing line further comprises a second station spaced apart
from the first station. The second station at least partially
sinters the inorganic material of the second portion of the tape to
form a third portion of the tape, where, at an instant, the tape
includes the green portion continuously connected to the third
portion by way of the second portion. For example, in some such
embodiments, the third portion of the tape is substantially more
bendable than the second portion such that a minimum bend radius
without fracture of the third portion is less than half that of the
second portion, and the green portion is substantially more
bendable than the second portion such that a minimum bend radius
without fracture of the green portion is less than half that of the
second portion. The manufacturing line may further include the tape
separation system described above.
[0006] Some aspects of the present disclosure relate to a sintering
system comprising a tape material comprising grains of inorganic
material and a sintering station. The sintering station includes an
entrance, an exit, and a channel extending between the entrance and
the exit. At an instant, the tape material extends into the
entrance of the sintering station, through the channel, and out of
the exit. Heat within the channel sinters the inorganic material
such that the inorganic material has a first porosity at the
entrance and a second porosity at the exit that is less than the
first porosity. Further, the wherein the tape material is
positively tensioned as the tape material passes through the
channel of the sintering station, thereby mitigating warpage. In
some embodiments, the tape material moves through the sintering
station at a speed of at least 1 inch per minute. In some
embodiments, the channel of the sintering station is heated by at
least two independently controlled heating elements, where the
heating elements generate a temperature profile where the channel
increases in temperature along the length of the channel in a
direction from the entrance toward the exit of the sintering
station, and where a sintering temperature in the channel exceeds
800.degree. C. In some embodiments, the sintering system further
includes a curved surface located along the channel of the
sintering station, where the tape material bends relative to a
widthwise axis of the tape material around the curved surface as
the tape material moves through the sintering station, thereby
influencing shape of the tape material. In some embodiments, the
exit and the entrance of the sintering station lie in a
substantially horizontal plane, such that an angle defined between
the exit and the entrance of the sintering station relative to a
horizontal plane is less than 10 degrees, thereby at least in part
controlling flow of gases relative to the channel; for example, in
some such embodiments, the sintering station further comprises an
upward facing channel surface defining a lower surface of the
channel, and a downward facing channel surface defining an upper
surface of the channel, where the downward facing channel surface
is positioned close to an upper surface of the tape material such
that a gap between the upper surface of the tape material and the
downward facing channel surface is less than 0.5 inches, thereby at
least in part controlling flow of gases in the channel. The tape
material may be particularly wide, long, and thin, having a width
greater than 5 millimeters, a length greater than 30 centimeters,
and a thickness between 3 micrometers and 1 millimeter, and the
inorganic material of the tape may be at least one of a
polycrystalline ceramic material and synthetic mineral.
[0007] Other aspects of the present disclosure relate to a process
for manufacturing ceramic tape, the process comprising a step of
sintering tape comprising polycrystalline ceramic to a porosity of
the polycrystalline ceramic of less than 20% by volume, by exposing
particles of the polycrystalline ceramic to a heat source to induce
the sintering between the particles. The tape is particularly thin
such that a thickness of the tape is less than 500 .mu.m, thereby
facilitating rapid sintering via heat penetration. Further, the
tape is at least 5 mm wide and at least 300 cm long. In some
embodiments, the process further includes a step of positively
lengthwise tensioning the tape during the sintering. In some such
embodiments, the process further includes a step of moving the tape
toward and then away from the heat source during the sintering. In
some embodiments, the amount of time of the sintering is
particularly short, that being less than two hours in aggregate,
thereby helping to maintain small grain size in the ceramic tape;
for example, in some such embodiments, the time in aggregate of the
sintering is less than one hour, and density of the polycrystalline
ceramic after the sintering is greater than 95% dense by volume
and/or the tape comprises closed pores after the sintering. In some
embodiments, the tape comprises a volatile constituent that
vaporizes during the sintering, where the volatile constituent is
inorganic, and where the tape comprises at least 1% by volume more
of the volatile constituent prior to the sintering than after the
sintering.
[0008] Still other aspects of the present disclosure relate to a
tape comprising a body comprising grains of inorganic material
sintered to one another. The body extending between first and
second major surfaces, where the body has a thickness defined as
distance between the first and second major surfaces, a width
defined as a first dimension of the first major surface orthogonal
to the thickness, and a length defined as a second dimension of the
first major surface orthogonal to both the thickness and the width.
The tape is long, having a length of about 300 cm or greater. The
tape is thin, having a thickness in a range from about 3 .mu.m to
about 1 mm. The tape is particularly wide, having a width of about
5 mm or greater. According to an exemplary embodiment, geometric
consistency of the tape is such that a difference in width of the
tape, when measured at locations lengthwise separated by 1 m, is
less than 100 .mu.m; and a difference in thickness of the tape,
when measured at locations lengthwise separated by 1 m along a
widthwise center of the tape, is less than 10 .mu.m. In some
embodiments, the tape is flat or flattenable such that a length of
10 cm of the tape pressed between parallel flat surfaces flattens
to within 0.05 mm of contact with the parallel flat surfaces
without fracturing; and for example in some such embodiments, when
flattened to within 0.05 mm of contact with the parallel flat
surfaces, the tape exhibits a maximum in plane stress of no more
than 1% of the Young's modulus thereof. In some embodiments, the
first and second major surfaces of the tape have a granular
profile, where the grains are ceramic, and where at least some
individual grains of the ceramic adjoin one another with little to
no intermediate amorphous material such that a thickness of
amorphous material between two adjoining grains is less than 5 nm.
In some embodiments, the body has less than 10% porosity by volume
and/or the body has closed pores. In some embodiments, the grains
comprise lithium, and the body has ionic conductivity of greater
than 5.times.10.sup.5 S/cm. In some embodiments, the body has a
particularly fine grain size, that being 5 .mu.m or less. In some
embodiments, the tape further includes an electrically-conductive
metal coupled to the first major surface of the body, where in some
such embodiments the body comprises a repeating pattern of vias,
and the electrically-conductive metal is arranged in a repeating
pattern. In some embodiments, the first and second major surfaces
have a granular profile, the tape further includes a coating
overlaying the granular profile of the first major surface, and an
outward facing surface of the coating is less rough than the
granular profile of the first surface, where
electrically-conductive metal coupled to the first major surface is
so coupled by way of bonding to the outward facing surface of the
coating. In some embodiments, the inorganic material has viscosity
of 12.5 poise at a temperature greater than 900.degree. C.
[0009] Additional aspects of the present disclosure relate to a
roll of the tape of any one of the above-described embodiments,
wherein the tape is wrapped around and overlapping itself, bent to
a radius of less than 30 cm.
[0010] Still other aspects of the present disclosure relate to a
plurality of sheets cut from tape of any one of the above-described
embodiments.
[0011] Some aspects of the present disclosure relate to a tape,
comprising a body comprising ceramic grains sintered to one
another, the body extending between first and second major
surfaces, where the body has a thickness defined as distance
between the first and second major surfaces, a width defined as a
first dimension of the first major surface orthogonal to the
thickness, and a length defined as a second dimension of the first
major surface orthogonal to both the thickness and the width; where
the tape is thin, having a thickness in a range from about 3 .mu.m
to about 1 mm; and where first and second major surfaces of the
tape have a granular profile, and at least some individual grains
of the ceramic adjoin one another with little to no intermediate
amorphous material such that a thickness of amorphous material
between two adjoining grains is less than 5 nm.
[0012] Some aspects of the present disclosure relate to a tape,
comprising a body comprising ceramic grains sintered to one
another, the body extending between first and second major
surfaces, where the body has a thickness defined as distance
between the first and second major surfaces, a width defined as a
first dimension of the first major surface orthogonal to the
thickness, and a length defined as a second dimension of the first
major surface orthogonal to both the thickness and the width; where
the tape is thin, having a thickness in a range from about 3 .mu.m
to about 1 mm; where first and second major surfaces of the tape
have a granular profile; and where the grains comprise lithium and
the body has ionic conductivity greater than 5.times.10.sup.5
S/cm.
[0013] Additional features and advantages will be set forth in the
detailed description that follows, and, in part, will be readily
apparent to those skilled in the art from the description or
recognized by practicing the embodiments as described in the
written description and claims hereof, as well as the appended
drawings.
[0014] It is to be understood that both the foregoing general
description and the following detailed description are merely
exemplary, and are intended to provide an overview or framework to
understand the nature and character of the claims.
[0015] The accompanying drawings are included to provide a further
understanding and are incorporated in and constitute a part of this
specification. The drawings illustrate one or more embodiment(s),
and together with the description serve to explain principles and
the operation of the various embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 shows an example of distorted, sintered ceramic tape
material formed without technology disclosed herein, such as
controlled green ribbon tensioning and other technology as
discussed herein.
[0017] FIG. 2 shows an example of distorted, sintered ceramic tape
material produced utilizing a temperature profile and tape speed
which caused non-uniform sintering.
[0018] FIG. 3 is a roll-to-roll system for producing a sintered
article according to an exemplary embodiment.
[0019] FIG. 4 is an enlarged view of an embodiment of the
separation system shown in FIG. 3, according to an exemplary
embodiment.
[0020] FIG. 5 is a side view of the continuous tape material,
according to an exemplary embodiment.
[0021] FIG. 6 is a perspective view of a vacuum drum, according to
an exemplary embodiment.
[0022] FIG. 7 is an enlarged view of the vacuum drum shown in FIG.
6, according to an exemplary embodiment.
[0023] FIG. 8 is an enlarged view of the peeler shown in FIG. 4,
according to an exemplary embodiment.
[0024] FIG. 9 is a conceptual side view of a station of a
manufacturing line to prepare green tape for sintering, according
to an exemplary embodiment.
[0025] FIG. 10 is a front perspective of the station of FIG. 9,
according to an exemplary embodiment.
[0026] FIG. 11 is a block diagram of a method for processing a
green tape to at least in part prepare the green tape for
sintering, according to an exemplary embodiment
[0027] FIG. 12 is a detailed view of the binder removal station and
the sintering station of the system of FIG. 3, according to an
exemplary embodiment.
[0028] FIG. 13 is detailed view of tape material within the channel
of the sintering furnace of FIG. 12, according to an exemplary
embodiment.
[0029] FIG. 14 shows sintered tape material exiting a sintering
furnace, according to an exemplary embodiment.
[0030] FIG. 15 is a view of the sintering station of FIG. 12
showing a heating system, according to an exemplary embodiment.
[0031] FIG. 16 is a graph of a prophetic thermal profile and
modeled sintering shrinkage versus distance for different tape
transport speeds, according to an exemplary embodiment.
[0032] FIG. 17 shows a prophetic sintering temperature profile
projected along the channel of a sintering furnace, according to an
exemplary embodiment.
[0033] FIG. 18 shows an inline multi-furnace sintering station,
according to an exemplary embodiment.
[0034] FIG. 19 shows prophetic temperature profiles for the two
sintering furnaces of FIG. 18, according to an exemplary
embodiment.
[0035] FIG. 20 shows a sintering system having two parallel
production systems, according to an exemplary embodiment.
[0036] FIG. 21 is a graph of sintering shrinkage of a zirconia tape
at various temperatures and times at temperatures including curves
fit to the data for each temperature.
[0037] FIG. 22 is a graph of a curve fit of a mathematical function
of the sintering shrinkage of a zirconia tape at various
temperatures and times at various temperatures.
[0038] FIG. 23 is a modeled graph of peak stresses at the
centerline of a zirconia tape during sintering as a function of
number of heating zones, passes, tape transport speed as a function
of tape width.
[0039] FIG. 24 is a modeled graph of peak stresses at the edge of a
zirconia tape during sintering as a function of the number of
heating zones, passes, and tape transport speed as a function of
tape width.
[0040] FIG. 25 is a modeled graph of shrinkage in a zirconia tape
during sintering using two passes through a single hot zone furnace
for two tape transport speeds.
[0041] FIG. 26 is a modeled graph of stress in a zirconia tape
during sintering using two passes through a single hot zone furnace
for two tape transport speeds.
[0042] FIG. 27 is a modeled graph of shrinkage in a zirconia tape
during sintering using two passes through a 10 hot zone furnace for
two tape transport speeds.
[0043] FIG. 28 is a modeled graph of stress (in MPa) in a zirconia
tape during sintering using two passes through a 10 hot zone
furnace for two tape transport speeds and various tape widths.
[0044] FIG. 29 is a perspective view of an illustration of a
portion of a sintered article, according to an exemplary
embodiment.
[0045] FIG. 30A is a digital image of an unpolished surface of a
sintered article.
[0046] FIG. 30B is a conceptual side profile of the sintered
article of FIG. 30A.
[0047] FIG. 31A is a digital image of a polished surface of a
sintered article.
[0048] FIG. 31B is a conceptual side profile of the sintered
article of FIG. 31A.
[0049] FIG. 32 is a side view along the width of a sintered article
according to one or more embodiments.
[0050] FIG. 33 is a drawing to illustrate the thin bending
equation.
[0051] FIG. 34A is a perspective side view of a rolled sintered
article, according to an exemplary embodiment.
[0052] FIG. 34B is a cross-sectional view of the rolled sintered
article of FIG. 34A, according to an exemplary embodiment.
[0053] FIG. 35 is a height profile of the sintered article of
Example 5, before being flattened, showing the measured height
above the flattening plane.
[0054] FIG. 36 is a height profile of the sintered article of
Example 6, before being flattened, showing the measured height
above the flattening plane.
[0055] FIG. 37 is a height profile of the sintered article of
Comparative Example 7, before being flattened, showing the measured
height above the flattening plane.
[0056] FIG. 38 is a height profile of the sintered article of
Comparative Example 8, before being flattened, showing the measured
height above the flattening plane.
[0057] FIG. 39 is a plot of the maximum height above the flattening
plane of each of the sintered articles of Examples 5-6 and
Comparative Examples 7-8.
[0058] FIG. 40 is a plot of the force required to flatten the
sintered articles of Examples 5-6 and Comparative Examples 7-8.
[0059] FIG. 41 is a plot of the pressure required to flatten the
sintered articles of Examples 5-6 and Comparative Examples 7-8.
[0060] FIG. 42 is a plot of the maximum in plane stress after
flattening in the sintered articles of Examples 5-6 and Comparative
Examples 7-8.
[0061] FIG. 43A is a deformation plot showing measured stress in
the bottom surface of the sintered article of Example 5, after
flattening.
[0062] FIG. 43B is a deformation plot showing measured stress in
the top surface of the sintered article of Example 5, after
flattening.
[0063] FIG. 44A is a deformation plot showing measured stress in
the bottom surface of the sintered article of Example 6, after
flattening.
[0064] FIG. 44B is a deformation plot showing measured stress in
the top surface of the sintered article of Example 6, after
flattening.
[0065] FIG. 45A is a deformation plot showing measured stress in
the bottom surface of the sintered article of Comparative Example
7, after flattening.
[0066] FIG. 45B is a deformation plot showing measured stress in
the top surface of the sintered article of Comparative Example 7,
after flattening.
[0067] FIG. 46A is a deformation plot showing measured stress in
the bottom surface of the sintered article of Comparative Example
8, after flattening.
[0068] FIG. 46B is a deformation plot showing measured stress in
the top surface of the sintered article of Comparative Example 8,
after flattening.
[0069] FIG. 47 is a cross-sectional view of a segment of a package
including the sintered article, according to an exemplary
embodiment.
[0070] FIG. 48 is a length-wise cross-sectional view of a segment
of a package including the sintered article, according to an
exemplary embodiment.
[0071] FIG. 49 is another cross-sectional view of a segment of a
package including the sintered article, according to an exemplary
embodiment.
[0072] FIG. 50 is an example method of making a package including
the sintered article, according to an exemplary embodiment.
[0073] FIG. 51 is another example method of making a package
including the sintered article, according to an exemplary
embodiment.
[0074] FIG. 52 is an example cross-sectional view of a segment of a
package including the sintered article and a "flip-chip"
configuration, according to an exemplary embodiment.
[0075] FIG. 53 is another example cross-sectional view of a segment
of a package including the sintered article and a "flip-chip"
configuration, according to an exemplary embodiment.
[0076] FIG. 54 is yet another example cross-sectional view of a
segment of a package including the sintered article and a
"flip-chip" configuration, according to an exemplary
embodiment.
[0077] FIG. 55 is another cross-sectional view of a segment of a
package including the sintered article, according to an exemplary
embodiment.
[0078] FIG. 56 shows a roll to roll system and related process for
producing a sintered article including a length of threading
material, according to an exemplary embodiment.
[0079] FIG. 57 is a detailed view showing bonding between a length
of threading material and tape material in the system of FIG. 56,
according to an exemplary embodiment.
[0080] FIG. 58 shows a roll to roll system including a sintering
station configured to form a curve along a longitudinal direction
of a continuous length of tape material, according to an exemplary
embodiment.
[0081] FIG. 59 is a detailed view of a sintering station including
an insert defining a curved lower surface of a sintering channel,
according to an exemplary embodiment.
[0082] FIG. 60 is a side view of a channel of a sintering station
having opposed curved upper and lower surfaces defining a sintering
channel, according to an exemplary embodiment.
[0083] FIG. 61 is a side schematic view of a sintering station
varying radiuses of curvature along the sintering channel,
according to an exemplary embodiment.
[0084] FIG. 62 shows a gas bearing having a curved upper surface
that defines a curved surface of a sintering channel, according to
an exemplary embodiment.
[0085] FIG. 63 shows a roller arrangement for forming the
longitudinal curve in a continuous length of tape during sintering,
according to an exemplary embodiment.
[0086] FIG. 64 shows an arrangement including multiple rollers for
forming multiple longitudinal curves in a continuous length of tape
during sintering, according to an exemplary embodiment.
[0087] FIG. 65 shows a free-loop arrangement for forming the
longitudinal curve in a continuous length of tape during sintering,
according to an exemplary embodiment.
[0088] FIG. 66 is a digital image of sintered tapes demonstrating
flattening produced when the tape bent during sintering.
[0089] FIGS. 67A and 67B are digital images of a roll of sintered
ceramic tape according to an exemplary embodiment.
[0090] FIG. 68 is a digital image of a roll of a sintered ceramic
tape according to another embodiment.
[0091] FIG. 69 is a digital image of a roll of a sintered ceramic
tape according to yet another embodiment.
[0092] FIG. 70 is a graphical representation of time sintering for
traditional batch firing versus the presently disclosed technology
according to an exemplary embodiment.
[0093] FIGS. 71A and 71B are top views of surfaces of sintered
articles according to exemplary embodiments.
[0094] FIGS. 72A and 72B are side perspective views of surfaces of
sintered articles according to exemplary embodiments.
[0095] FIGS. 73A, 73B, and 73C are micrographs of grain boundaries
of sintered articles according to exemplary embodiments.
[0096] FIGS. 74 and 75 are micrographs of grain boundaries of
sintered articles according to other exemplary embodiments.
[0097] FIGS. 76 and 77 are top views of surfaces of sintered
articles according to exemplary embodiments.
[0098] FIG. 78 is a digital image of a tape of a sintered article
according to an exemplary embodiment.
[0099] FIGS. 79A and 79B are side views sintered articles according
to exemplary embodiments.
[0100] FIG. 80 is a side view of a sintered article according to an
exemplary embodiment.
[0101] FIG. 81 is a side view of a sintered article according to
another exemplary embodiment, where the sintered material appears
amorphous.
[0102] FIG. 82 is a graphical representation of compositions.
[0103] FIGS. 83 and 84 are side perspective views of surfaces of
sintered articles according to exemplary embodiments.
[0104] FIGS. 85A and 85B are side perspective views of surfaces of
un-sintered green material according to exemplary embodiments.
[0105] FIGS. 86A and 86B are side perspective views of surfaces of
sintered material according to exemplary embodiments.
[0106] FIG. 87 is a graphical representation of viscosity versus
temperature for various materials.
[0107] FIG. 88A is a graphical representation of a temperature
profile through a sintering furnace according to an exemplary
embodiment.
[0108] FIG. 88B is a schematic diagraph of the sintering furnace of
FIG. 88A.
[0109] FIG. 89 is a schematic diagraph of a sintering furnace
according to another exemplary embodiment.
[0110] FIG. 90A is a graphical representation of a temperature
profile through a sintering furnace according to another exemplary
embodiment.
[0111] FIG. 90B is a schematic diagraph of the sintering furnace of
FIG. 90A.
[0112] FIGS. 91A and 91B are side perspective views of surfaces of
sintered material according to exemplary embodiments.
[0113] FIG. 92 is a side view of a sintered material according to
an exemplary embodiment.
[0114] FIG. 93 is a schematic diagraph of electronics in the form
of a battery according to an exemplary embodiment.
[0115] FIGS. 94 and 95 are graphical representations of sintering
schedules according to exemplary embodiments.
[0116] FIG. 96 is a graphical representation of sintering
temperature versus ionic conductivity for sintered articles
according to exemplary embodiments.
[0117] FIG. 97 is a graphical representation of sintering
temperature versus percentage of cubic garnet for sintered articles
according to exemplary embodiments.+
[0118] FIGS. 98 and 99 are side perspective views of surfaces of
sintered material according to exemplary embodiments.
[0119] FIGS. 100A and 100B are tops views of surfaces of one side
of a sintered material and
[0120] FIGS. 101A and 101B are tops views of surfaces of another
side of the sintered material according to an exemplary
embodiment.
[0121] FIG. 102 is a side view of a sintered material according to
an exemplary embodiment.
[0122] FIG. 103 is a digital image of a sintered material with a
layer providing a smooth surface according to an exemplary
embodiment.
[0123] FIG. 104 is a schematic diagraph of electronics in the form
of a stack of sintered articles according to an exemplary
embodiment.
DETAILED DESCRIPTION
[0124] Referring generally to the figures, various embodiments of a
system and process for manufacturing long, thin and/or wide
sintered articles are shown and described, where by the term sinter
Applicant refers to the process of coalescing (e.g., directly
bonding to one another) particles or grains (e.g., of a powdered or
granular material) into a solid or porous body by heating the
particles or grains without completely liquefying the particles or
grains such that crystal structure of the particles or grains
remain in the coalesced body, however aspects of the present
inventive technology may be used to manufacture amorphous material,
such as those that are difficult or impossible to process using
conventional manufacturing techniques, as may be intuitive to those
of skill in the art of inorganic material processing. In addition,
Applicant has discovered that new sintered articles having a
variety of properties may be formed using the systems/processes
discussed herein that were previously unachievable utilizing prior
technology. Specifically, Applicant has developed material handling
systems and processes that allow for a very precise level of
control of a variety conditions/forces that the material
experiences during formation of the sintered article, and that this
precise control/material handling allows for production of long,
thin and/or wide sintered tape materials believed to be
unachievable with prior systems. Further, articles manufactured
using technology disclosed herein may have other unique qualities,
such as: strength, such as may be due to low number defects;
purity, such as may be due to controlled airflow and sintering
duration, and properties related to purity, such as dielectric
constant and impermeability; consistency, such as along a length
and/or widthwise, such as in terms of flatness, thickness,
roughness, grain size, etc.; and other unique attributes.
[0125] In general, the system described herein utilizes an input
roll of web supported green tape wound on a spool or reel. As
explained in more detail below, the web supported green tape
includes a green tape material including grains of inorganic
material (e.g., such as grains of ceramic material, grains of
polycrystalline ceramic material, metal grains or grains of
synthetic material) bound with an organic binder material, and the
green tape material is supported on carrier web (e.g., a sheet of
polymer material). The input roll of web supported green tape is
unwound, and the carrier web/backing layer is carefully separated
from the green tape material. Applicant has found that by precisely
controlling separation of the carrier web from the green tape with
little or no distortion of the green tape, a sintered article
having various properties (e.g., thickness, flatness, density,
shape etc.) that are very consistent/controlled along its length
can be produced. With that said, in other contemplated embodiments
the green tape may not be web supported and/or may not be on a
roll, such as if the tape is formed in-line, such as along the
manufacturing line prior to sintering.
[0126] Following removal of the carrier web, the self-supporting
green tape (including the grains of inorganic material supported by
organic binder material) is moved through a binder removal station.
In general, the binder removal station applies heat to the
self-supporting green tape in a manner that removes or chemically
alters the organic binder such that the tape material exiting the
binder removal station is an unbound tape material. By unbound,
Applicants refer to the binder material having been removed,
however the unbound tape may still hold together, such as via char
of the burned binder or by interweaving or bonding between the
inorganic particles, or by other means (e.g., electrostatic forces,
air pressures). Following removal of the organic binder, the
unbound tape material is moved into a sintering station that
applies heat to the unbound tape material that sinters (e.g., fully
sinters or partially sinters) the inorganic particles forming a
sintered article which exits the sintering station.
[0127] Applicant has found that, surprisingly, the grains of
inorganic material will support themselves as an unbound tape
material even after the organic binder is removed and/or that the
tape may be otherwise supported, as described above. However,
following removal of the organic binder, the unbound tape material
is very delicate prior to sintering or may be very delicate prior
to sintering. Thus, Applicant has further identified a new binder
removal and sintering station arrangement that allows for handling
of the delicate unsupported tape material in a manner that allows
for production of very high quality sintered articles. (By
unsupported in the preceding sentence, Applicant means unsupported
by organic binder after the binder has been removed or burned.) In
particular, wide, long, high quality sintered articles suitable for
roll to roll handling are produced without introducing substantial
distortion or without breaking the article during binder removal or
sintering.
[0128] In particular, Applicant has identified that air flow (e.g.,
turbulent air flow generated by thermal gradients) within the
binder removal station and/or sintering station may impinge upon
the tape material causing distortion or breakage of the tape
material. Further, Applicant has discovered that a highly
horizontal processing path within the binder removal station and/or
sintering station reduces or eliminates turbulent airflow which in
turn produces or may produce sintered articles without significant
distortion. Further, Applicant has determined that eliminating air
flow based distortion is particularly important when forming wide
sintered articles (e.g., articles having width greater than 5 mm)
because Applicant believes that susceptibility to air flow based
distortion increases as the width of the tape material increases.
Further, Applicant has determined that eliminating or reducing air
flow based distortion is particularly important to allow for roll
to roll processing as Applicant has found that even minor levels of
distortion may cause the sintered article to break or otherwise not
wind properly on the uptake reel (also called a tape-up reel).
[0129] Identification of horizontal positioning of the tape during
binder removal and/or sintering was a surprising discovery given
the inorganic green material and prior sintering technologies. For
example, some tape material sintering may use downwardly angled
positioning (e.g., a 12 to 20 degree downward incline) of the tape
material as a means of utilizing gravity to pull the delicate tape
material through the heating steps of the system, possibly intended
for application of an evenly distributed force across the tape
material to pull the tape material through heating steps of the
process.
[0130] However, Applicant has discovered that when the heating
portions of a sintering system are positioned at an incline,
turbulent air flows may form as the hot air rises through channels
of the heating system that holds the tape material. Thus, this
flowing air impinges on the tape material, possibly forming
distortions or potentially breaking the tape. Further Applicant
discovered that incidence of air flow based distortions created in
the sintered tape formed using a non-horizontal heating arrangement
may increase as the width of the tape material increases. With that
said, aspects of technology disclosed herein may be used with
systems that include non-horizontal heating channels or systems,
such as a binder removal station. Further, aspects of technology
disclosed herein, such as unique materials and form factors (e.g.,
thin ribbons of garnet or other materials or geometries), may be
manufactured using non-horizontal heating channels or systems.
[0131] Applicant attempted to sinter a wider tape (e.g. a tape
having a width greater than 5 mm, and specifically a green tape of
25 microns thickness, width of 32 mm, with zirconia--3 mole %
Y.sub.2O.sub.3 inorganic particles) using an incline arrangement.
As shown in FIG. 1, when partially sintered at 1250.degree. C., the
partially sintered article formed had significant and periodic
distortions or bubbles along the length of the tape. The height of
the distortion was on the order of greater than 1 mm and were large
enough to prevent spooling of the tape on a core having a diameter
of 3-6 inches. Applicant believes that the bubbles were formed as
turbulent air flow pushed upward on the tape as the hot air flowed
up the sloped support surface underneath the tape during the heated
stages of tape processing (e.g., during sintering and binder
removal).
[0132] In addition to air flow control, Applicant has identified
that control of the thermal profiles within the binder removal
station and/or sintering station is or may be important to forming
a high quality sintered article. In particular, Applicant has
discovered that when heating a wide tape material in a roll to roll
process, such as the one discussed herein, the thermal stresses
that the tape material is exposed to, particularly during
sintering, should be precisely controlled to limit distortion or
breakage that may otherwise occur as the tape material
shrinks/densifies during sintering for at least some materials
and/or forms disclosed herein, such as at least some thin, wide
tapes of inorganic material. As an example shown in FIG. 2, a
section of ceramic tape (specifically alumina tape) including the
portion of the tape at the transition from unsintered to sintered
material is shown as formed using a process with steep temperature
increases within the high temperature sintering zone. As shown in
FIG. 2, this steep temperature increase causes or may cause
distortion or cross-web shape due to stress internal to the tape
material as the tape sinters following the fast rise in temperature
in the sintering zone. With that said, in other embodiments, such
as for different materials (e.g., lithium garnet), a steep
temperature increase may be beneficial, such as by reducing
exposure to oxidation or impurities, and distortions may be
controlled via other factors, such as air flow control and narrower
width of tape for example.
[0133] Thus, as shown and described below, Applicant has determined
that by utilizing a sintering furnace with independently controlled
heating zones and/or multiple independently controlled sintering
furnaces, a wide, long segment of tape material may be sintered
without significant distortion and/or breakage at a high process
throughput rate. Similarly, the binder removal furnace and
sintering furnaces are designed and positioned relative to each
other to limit the thermal shock (e.g., exposure to a sharp
temperature gradient) that the tape is exposed to as the tape
transitions between different heated zones within the system
discussed herein.
[0134] Following sintering, the wide, sintered tape is or may be
wound onto an uptake reel forming a roll of sintered tape material.
In contemplated embodiments the roll is cylindrical or otherwise
shaped, such as when rolled around geometry that is not circular,
such as oblong, triangular with rounded vertices, etc. Because of
the high quality (e.g., low distortion) of the tape formed by the
system(s) discussed herein, in at least some embodiments the tape
may be wound into a roll in a manner that allows for the sintered
tape roll be used conveniently and efficiently in subsequent
manufacturing processes, e.g., as a substrate in downstream,
roll-to-roll manufacturing processes. Applicant has found that the
high level of width, length, thickness, shape and/or flatness
consistency and/or other attributes (purity, strength,
impermeability, dielectric performance) of the tape or other
articles produced by the system(s) discussed herein allows for
spooling of the tape on the uptake reel. In contrast, a tape with
high levels of distortion or irregularities would or may tend to
break or otherwise form a distorted, inconsistent tape roll and may
be unsuitable for uptake onto a reel to form a roll of sintered
tape. With that said, some contemplated non-horizontal sintering
systems, especially those that employ technology disclosed herein,
may allow for undistorted tapes, such as if air flow is controlled,
the tape is thin enough and sufficiently tensioned, the rate of
sintering and temperatures are controlled, for example, as
disclosed herein.
[0135] Lastly, some conventional sintered articles are formed in
systems in which discreet unsintered pieces or pieces of green tape
are placed upon a surface, called a setter board, and placed inside
a furnace that burns off the organic binder and sinters the
inorganic grains. Applicant has identified that roll-to-roll
formation of a sintered article will provide a number of advantages
not found by discreet, conventionally sintered articles. For
example, wide, wound rolls of sintered articles can be formed at
high throughput speeds (e.g., speed of 6 inches per minute or
greater). In addition, system(s)/process(es) discussed herein forms
wide, thin sintered (e.g., thin ceramic and/or sintered articles)
which allows for use of the sintered article as a substrate to form
small and low cost devices (e.g., semi-conductor devices,
batteries, etc.). Similarly, providing a roll of sintered material
allows the sintered material be used as an input substrate roll to
high throughput downstream manufacturing processes, further
allowing for downstream articles to be formed at high speed and/or
at low cost utilizing the sintered articles discussed herein.
System Overview
[0136] Referring to FIG. 3, a system 10 for producing a sintered
tape article is shown according to an exemplary embodiment. In
general, green tape material is provided to system 10 at an input
side, separation system 12, and the green tape material moves
through system 10 generally in the processing direction 14. Within
separation system 12, a source 16 of continuous tape material 18
(`continuous` meaning long lengths, as disclosed herein, such as
300 cm or longer, which can be provided in the form of a spool or
belt) is provided, and is fed to the downstream portions of system
10.
[0137] In general, continuous tape material 18 includes a layer of
green tape material 20 that includes grains of inorganic,
sinterable material bound together with an organic binder (e.g.,
(e.g., polyvinyl butyral, dibutyl phthalate, polyalkyl carbonate,
acrylic polymers, polyesters, silicones, etc.). The green tape
material 20 of the continuous tape material 18 is or may be
supported on a carrier web or backing layer 22. As will be
discussed in more detail below, in specific embodiments, system 10
is configured to form long, wide and/or thin sintered articles and
in such embodiments, the green tape material 20 coming into the
system 10 is also relatively long, wide and/or thin. For example,
in specific embodiments, green tape material 20 has a width greater
than 5 mm, greater than 10 mm, greater than 40 mm or greater than
125 mm. In specific embodiments, green tape material 20 has a
length greater than 10 meters (m), specifically greater than 30 m,
and more specifically greater than 60 m. In specific embodiments,
green tape material 20 has a thickness between 3 microns and 1
millimeter. In addition, incoming green tape material 20 has a
porosity that is greater than the porosity of the sintered article
produced by system 10. In other contemplated embodiments, the green
tape material 20 may have a width less than 5 mm, such as at least
0.5 mm, at least 1 mm, at least 2.5 mm, or smaller than 0.5 mm in
some such embodiments. Similarly, the tape may have another
thickness and/or length and/or porosity. In some embodiments, the
tape material 20 may have a non-rectangular cross-section
orthogonal to its length, such as round, oblong, parallelogram,
rhomboid, etc., where, as may be intuitive, width of such
embodiments refers to a maximum cross-sectional dimension
orthogonal to length and thickness is a minimum cross-sectional
dimension orthogonal to length.
[0138] Separation system 12 includes carrier web removal station
24. At carrier web removal station 24, carrier web 22 is separated
from green tape material 20, and the removed carrier web 22 is or
may be wound onto an uptake reel 26. In general, carrier web
removal station 24 includes a tension isolator 28, which can
include a vacuum drum, and a peeler 30 that removes carrier web 22
in manner that does not distort or compress green tape material 20
and that isolates the tension within carrier web 22 generated by
uptake reel 26 from green tape 20. Following separation from
carrier web 22, green tape 20, is or may be a self-supporting green
tape including the grains of inorganic material supported by the
organic binder material, but does not include a carrier web or
other support structure to hold the tape material together during
downstream processing through system 10.
[0139] Self-supporting green tape 20 moves or may move into an
ultralow tension control system 32. In general, self-supporting
green tape 20 is a relatively delicate structure that is being
pulled through system 10 via the operation of various spools,
reels, rollers, etc. The pulling action imparts a tension to
self-supporting green tape 20. Applicant has found that a uniform,
low level (e.g., gram levels; 0.1 grams to less than 1 kg; at least
1 gram, at least 5 grams, and/or no more than 100 grams, depending
upon the tape size and binder strength) of tension applied to
self-supporting green tape 20 is or may be advantageous as it
improves various characteristics, such as cross-width shape and
flatness of the final sintered article. However, due to the
delicate nature of the self-supporting green tape 20 (which becomes
even more delicate following binder removal as described in more
detail below), the low level of tension is precisely controlled
such that enough tension is provided to tape 20 to limit distortion
during binder removal/sintering of tape 20 while also limiting
maximum tension to ensure tape 20 does not break. With that said,
in other contemplated embodiments, greater tension, such as for
stronger tapes, or zero tension, other than tension due to weight
of the tape itself, is applied.
[0140] In one or more embodiments, as shown in FIG. 3, tension
control system 32 includes an ultralow tension dancer 33 which
utilizes lightweight, low inertia carbon fiber rollers. Ultralow
tension dancer 33 may include air-bearings to facilitate low
friction rotation of the carbon fiber rollers of tension dancer 33.
In other embodiments, a free loop of material or a vacuum box may
be utilized to provide consistent, gram levels of tension to tape
20.
[0141] Following tension control system 32, self-supporting green
tape 20 moves into binder removal station 34. In general, binder
removal station 34 includes one more heating element that delivers
heat to a channel formed with the station 34. Heat within binder
removal station 34 chemically changes and/or removes at least a
portion of the organic binder material of self-supporting green
tape 20 such that an unbound tape 36 exits binder removal station
34. In general, unbound tape 36 includes the grains of inorganic
material with very little or no organic binder remaining. Applicant
has found that unbound tape 36 will hold itself together even
without the presence of the organic binder in manner that allows
the unbound tape 36 to be moved into sintering station 38, such as
utilizing the tension-control, air flow control, proximity of the
binder removal station 34 to the sintering station 38 and
temperature control therebetween, orientation and alignment of the
tape and stations 34, 38 as shown in FIG. 3.
[0142] In general, binder removal station 34 is arranged and
controlled in a manner that provides for low distortion of tape 20
as it traverses the binder removal station 34. Further, binder
removal station 34 may include heating elements that allow for
removal of volatile organic compounds without applying too much
heat too quickly, which otherwise may ignite the organic binder
compounds. Ignition may also be controlled by air flow.
[0143] In addition, binder removal station 34 is positioned in
manner relative to sintering station 38 such that the thermal shock
or temperature gradient that unbound tape 36 is exposed to during
movement from binder removal station 34 into sintering station 38
is low (e.g., spaced apart, but with pathways aligned linearly and
respective openings aligned and/or close to one another, such as
within 1 m, such as within 10 cm, such as within 2 cm, and/or
closer). Applicant has found that due to the delicate nature of
unbound tape 36, limiting the thermal shock experienced by the tape
36 between stations 34 and 38 further provides for production of
flat, consistent and/or unwarped sintered tape by
limiting/eliminating distortion that would otherwise occur due to
the temperature gradients experienced between stations 34 and
38.
[0144] In various embodiments, temperature within station 34 is
precisely controlled to achieve the desired properties of tape 36
leaving station 34. In various embodiments, the temperature within
station 34 is between 200 degrees Celsius (.degree. C.) (or about
200.degree. C.) and 500.degree. C. (or about 500.degree. C.), and
station 34 is heated to provide a temperature profile along its
length such that very little or no binder material remains within
the tape material exiting binder removal station 34. Further, in
some embodiments, some sintering (e.g., shrinkage, increase in
density, decrease in porosity, etc.) of the grains of inorganic
material may occur during traversal of binder removal station
34.
[0145] Following binder removal in station 34, unbound tape 36
moves into the sintering station 38. In general, sintering station
38 includes one or more heating element (see, e.g., further
discussion of heating elements and types thereof below) that heats
sintering station 38 to temperatures above 500 degrees .degree. C.
(e.g., between 500.degree. C. (or about 500.degree. C.) and
3200.degree. C. (or about 3200.degree. C., such as 3200.degree.
C.+10% of 3200.degree. C.)) which causes sintering of the grains of
inorganic material of unbound tape 36. In general, the porosity of
the inorganic material decreases during sintering. This decrease in
porosity may also result in a shrinkage (e.g., a reduction in
width, thickness, length, etc.) of the tape material as the
material is sintered, such as in sintering station 38. With some
materials, during sintering, the elastic modulus can increase, the
strength can increase, the shape of the porosity can change,
without a significant decreasing in porosity or significant
shrinkage. In some embodiments, the sintering station 38 transforms
the tape 38 into a bisque material that is partially, but not fully
sintered.
[0146] Applicant has found that as unbound tape 36 traverses
sintering station 38, the unbound tape 36 is susceptible to
deformation or breakage which may be caused by a variety of forces
that the unbound tape 36 encounters during sintering. In
particular, as noted above, Applicant has discovered that forces
caused by turbulent air flow through sintering station 38 is one
source of significant deformation, and Applicant has also found
that the stress internal to tape 36 during sintering is another
significant potential source of deformation. Based on these
discoveries, Applicant has arranged or configured sintering station
38 in variety of ways in order to limit these forces to produce a
sintered article having acceptably low levels of distortion.
[0147] In particular, as shown in FIG. 3, sintering station 38 is
arranged in a substantially horizontal arrangement such that
unbound tape 36 traverses station 38 in a substantially horizontal
orientation. Applicant has found that by maintaining the
substantially horizontal arrangement of sintering station 38,
turbulent airflow can be reduced or minimized, which in turn
results in formation of a sintered tape material at the output of
sintering station 38 that has low levels of deformation, low levels
of cross-tape shape, and/or is flat. In various embodiments,
Applicant believes that for various wide tape materials, low
turbulence and consequently low distortion can be achieved by
maintaining an angle less than 10 degrees, specifically less than 3
degrees and even more specifically less than 1 degree between the
processing path of the tape material relative to the horizontal
plane. In some embodiments, the tape may move over an arced path
that is generally horizontal, as discussed below. In still other
embodiments, the path through the sintering station 38 may be more
inclined than 10 degrees above horizontal, as discussed above.
[0148] As shown in the embodiment of FIG. 3, binder removal station
34 is also positioned in the substantially horizontal position such
that turbulent air flow does not cause distortion, breakage, etc.
during the heating with binder removal station 34. Similarly,
binder removal station 34 is aligned in the vertical direction
(i.e. so that the respective openings are aligned and face one
another) with sintering station 38 such that unbound tape 36
remains in the horizontal position as tape 36 traverses from binder
removal station 34 to sintering station 38.
[0149] In addition, Applicant has discovered that if unbound tape
36 is exposed to a temperature profile along the length of
sintering station 38 that has drastic rises/drops in temperature,
high levels of stress are or may be generated within tape 36 which
in turn causes or may cause deformation or breakage of tape 36
during sintering. Further, Applicant has discovered that the
sintering stresses increase the risk of deformation as the width of
tape 36 increases. Thus, based on these discoveries, Applicant has
determined that by utilizing a sintering station 38 with multiple,
independently controllable heating elements (and potential multiple
sintering furnaces), a temperature profile along the length
sintering station 38 can be generated that keeps the stress with
tape 36 below a threshold that Applicant has discovered that tends
to causes deformation or breakage based on a particular tape
configuration.
[0150] Following traversal of sintering station 38, a partially or
fully sintered tape material 40 exits sintering station 38 and
enters the output side, uptake system 42. Sintered tape material 40
is wound upon uptake reel 44. An interlayer support material 46 is
paid off of a reel 48. Support material 46 is wound unto uptake
reel 44 such that a layer of support material 46 is or may be
located between each layer or at least some layers of sintered tape
material 40 on uptake reel 44. This arrangement forms a roll or
spool of supported sintered tape material 50. In general, support
material 46 is a compliant, relatively high friction material that
allows sintered tape material 40 to be held on to uptake reel 44 at
a relatively low wind tension. The compliance of support material
46 can compensate for cross-web shape that may be present in tape
40 (sintered tape material 40). The support material 46 also
increases friction between adjacent layers of tape 40 (sintered
tape material 40) on reel 44 which limits tape 40 (sintered tape
material 40) from sliding/telescoping of reel 44. Applicant
believes that without support material 46, sintered tape material
40 tends to slide off (e.g., telescope) of spool 50 at least in
part because the modulus of sintered tape 40 (sintered tape
material 40) is relatively high, limiting the ability of tape 40
(sintered tape material 40) to stretch under wind tension, which in
turn tends to or may result in poor roll integrity.
[0151] As discussed herein, system 10 is configured to form a
sintered tape material 40 having low levels of distortion, low
level risk of breakage, consistent properties along its length,
etc. despite the width and/or length of the sintered article. As
Applicant has discovered, the risk of distortion and breakage of
tape at various stages of system 10 may increase, particularly as
the width of the tape increases. For example, in specific
embodiments, sintered tape 40 (sintered tape material 40) has a
width greater than 5 mm, greater than 10 mm, greater than 40 mm or
greater than 125 mm, and the various arrangements of system 10
discussed herein limit the deformation or breakage risk despite the
width of the tape material. In other embodiments the sintered tape
has a width less than 5 mm and/or at least 0.5 mm, such as at least
1 mm, such as at least 2 mm.
[0152] In addition, the various material handling and heating
mechanism(s) of system 10 allow for sintered tape 40 (sintered tape
material 40) to be formed at a high throughput rate. In specific
embodiments, the roll to roll processing of system 10 allows for
production of sintered tape at speeds believed to be substantially
faster than other sintering processes, such as tunnel kiln
processing in at least some instances, such as conventional tunnel
kiln processing. In specific embodiments, system 10 is configured
to produce sintered tape 40 at a rate of at least 6 inches per
minute, at least 8 inches per minute, at least 19 inches per
minute, at least 29 inches per minute, and at least 59 inches per
minute. In yet additional specific embodiments, system 10 is
configured to produce sintered tape 40 at a rate of at least 3
inches per minute for green tape 20 having a width greater than 50
mm, of at least 5 inches per minute for green tape 20 having a
width between 35 mm and 50 mm, of at least 9 inches per minute for
green tape 20 having a width between 15 mm and 35 mm, and of at
least 10 inches per minute for green tape 20 having a width between
5 mm and 15 mm. In additional specific embodiments, system 10 is
configured to produce sintered tape 40 at a rate of at least 1
inches per minute (ipm) for green tape 20 having a width greater
than 50 mm, of at least 1.5 inches per minute for green tape 20
having a width between 35 mm and 50 mm, of at least 2 inches per
minute for green tape 20 having a width between 15 mm and 35 mm,
and of at least 3 inches per minute for green tape 20 having a
width between 5 mm and 15 mm.
Support Web Removal Station
[0153] Formation of the embodiments of the sintered articles
described herein includes applying a uniform web tension to the
green tape material before and after sintering. The separation
system according to one or more embodiments of this disclosure is
designed to apply such uniform web tension, along with uniform
velocity, to a green tape material as it is separated from a
supporting carrier web. Accordingly support of web removal, as
disclosed herein, allows for consistency of the shape of the green
tape material, reducing or eliminating instances of necking or
contracting of the green tape as well as reducing or eliminating
instances of imprinting features of surfaces of the equipment on
the green tape, which in turn may otherwise be present in the
sintered tape. With that said, technology disclosed herein may be
used without the support web removal station to produce new
sintered tapes as disclosed herein, where the tapes may have
characteristics attributed to the lack of support web removal
station, such as changes in thickness, repeating imprinted surface
features, etc.
[0154] As noted above, system 10 includes a support web removal
station generally at the input side of system 10. One aspect of the
support web removal station includes a separation system 12.
Referring to FIG. 4, the separation system 12 is configured to
separate a green tape material 20 from a carrier web 22 such that
the green tape material 20 can be processed downstream. In one or
more embodiments, a source 16 of continuous tape material 18 to be
separated is provided. As shown more clearly in FIG. 5, the
continuous tape material 18 includes the green tape material 20
supported on the carrier web 22. In FIG. 4, the source 16 is
provided in the form of a spool that unwinds the continuous tape
material 18 to a carrier web removal station 24 (including a
tension isolator 28 and a peeler 30). In one or more embodiments,
the source 16 may include a belt or other form to feed a continuous
tape material. In other contemplated embodiments, a source of the
green tape material may be another station on the manufacturing
line that continuously produces or may continuously produce green
material, form and condition green tape for subsequent handling in
the system(s) disclosed herein. Still other contemplated
embodiments may use green tape material separated by organic
material that is burned or otherwise removed, such as by the binder
removal station disclosed herein.
[0155] According to an exemplary embodiment, the green tape
material 20 includes grains of inorganic material (as described
herein) that are sinterable and are bound together with an organic
binder. The carrier web 22 may include a polymer, paper or a
combination of a polymer and a paper material. In some embodiments,
the green tape material includes an amount of polymer that is less
than the polymer content of the carrier web 22, where polymer
content is in terms of volume percent of the respective material.
According to an exemplary embodiment, the green tape material 20
and the carrier web 22 each have a respective thickness (t) defined
as a distance between the first major surface and the second major
surface, a respective width (W) defined as a first dimension of one
of the first or second surfaces orthogonal to the thickness, and a
respective length (L) defined as a second dimension of one of the
first or second surfaces orthogonal to both the thickness and the
width, such as for green tape having a continuous cross-sectional
geometry that is rectangular or oblong (e.g., where edges may be
removed after sintering to form straight sides). In other
contemplated embodiments, a tape of inorganic, sinterable material
may be held together by an inorganic binder, such as an inorganic
binder that becomes part of the sintered tape after processing in
the system 10. In still other contemplated embodiments, the tape of
inorganic material may be held together by bonding of the inorganic
material to itself, such as with a partially sintered bisque tape
as opposed to green tape, as disclosed herein, for example.
[0156] As will be described herein, according to an exemplary
embodiment, the carrier web 22 provides or may provide the primary
contact surface for conveying the continuous tape material through
the separation system 12 and, in particular conveying the
continuous tape material through the carrier web removal station
24. In other words, in at least some such embodiments the carrier
web 22 is primarily contacted, leaving the green tape material 20
substantially uncontacted and thus, is substantially free of
defects or flaws that are or may be generated by contact, such as
repeating surface features due to imprinting of the surface of a
wheel or roller on the green material of the tape that may be
detectable in a finished sintered product. Other embodiments may
include such defects or flaws, such as when aspects of technology
disclosed herein are used without the carrier web removal station
24, for example.
[0157] When the source 16 is a spool, the continuous tape material
has a first tension, which is relatively low (as will be further
described herein) and has a propensity to unwind at relatively high
speeds even when the continuous material is held in a constant and
low tension. The separation system 12 functions or may function as
a brake to reduce or otherwise control or limit the speed of unwind
of the continuous tape material from the source 16.
[0158] According to at least some such exemplary embodiments, the
carrier web removal station 24 includes a tension isolator 28
positioned in proximity to and downstream from the source 16 and a
peeler 30 positioned downstream from the tension isolator 28. The
tension isolator 28 and peeler 30 separate the carrier web 22 from
green tape material 20 without damaging the green tape material. In
particular the tension isolator 28 is designed and used to grip the
carrier web and pace the velocity of the continuous tape material
through the separation system. In one or more embodiments, after
the carrier web 22 is separated from the green tape material, the
speed at which the carrier web 22 is collected after separation
from the green tape material 20 is controlled to maintain constant
tension in the carrier web 22, and thus in the continuous green
tape material 20. In one or more embodiments, the tension isolator
28 isolates the separation of the carrier web 22 from the green
tape material 20 from the quality of the incoming green tape
material 20 from the source 16. Without the tension isolator 28,
any or some inconsistencies in the wind quality of the continuous
tape material (i.e. too loose a wind, which can result in cinching
during unwinding or feeding to the peeler 30) can cause tension and
velocity variations at the peeler 30.
[0159] According to an exemplary embodiment, the continuous tape
material 18 is fed at a first tension to the tension isolator 28,
and the tension isolator of one or more embodiments has a structure
or is configured to apply a second tension to carrier web 22, which
is greater than the first tension of the continuous tape material
18, when conveying the continuous tape material 18 to the peeler
30. In some embodiments, the second tension (i.e. tensile force) is
at least 20% greater than the first tension and/or at least 25
millinewtons (mN) greater, such as at least 100 mN greater, such as
at least 200 mN greater. According to some such embodiments, the
second tension is applied to the carrier web 22, but not or at
least substantially not applied to the green tape material. In one
or more embodiments, the green tape material 20 maintains the first
tension as the continuous tape material is moved along the tension
isolator 28. In one or more embodiments, as the continuous tape
material is moved along the tension isolator 28, the green tape
material comprises or has no tension or no tension beyond tension
to support its own weight, or substantially no tension beyond
tension to support its own weight, such as less than 1 newton (N)
beyond tension to support its own weight. Accordingly, the tension
isolator 28 creates a first tension zone 17 between the tension
isolator 28 and the source 16 and a second tension zone 19 between
the tension isolator 28 and the peeler 30. The tension applied to
the carrier web 22 in the first tension zone 17 is less than the
tension applied to the carrier web 22 in the second tension zone
19. In one or more embodiments, the tension (i.e. tensile stress)
applied to the carrier web 22 in the second tension zone 19 is
about 2.5 pounds per (linear) inch (PLI) or less. For example, in
one or more embodiments, the tension applied to the carrier web 22
is about 2.4 PLI or less, about 2.3 PLI or less, about 2.2 PLI or
less, about 2.1 PLI or less, about 2 PLI or less, about 1.8 PLI or
less, about 1.6 PLI or less, about 1.5 PLI or less, about 1.4 PLI
or less, about 1.2 PLI or less, or about 1 PLI or less. In one or
more embodiments, the first tension is equal to or less than about
50% (e.g., about 45% or less, about 40% or less, about 35% or less,
about 30% or less, or about 25% or less) of the second tension. In
some embodiments, tension (i.e. tensile force) applied to the
carrier web 22 in the second tension zone 19 is at least 20%
greater than tension applied to the carrier web 22 in the first
tension zone 17 and/or at least 25 millinewtons (mN) greater, such
as at least 100 mN greater, such as at least 200 mN greater. In one
or more embodiments, (nominal) additional tension is applied to the
green tape material, other than the tension that is applied on the
green tape material through the application of tension on the
carrier web 28. In such embodiments, the carrier web may stretch
due to such application of tension on the carrier web, which in
turn creates some tension on the green tape material, such as where
the overwhelming bulk of tension is borne by the carrier web.
[0160] In one or more embodiments, the tension isolator 28 applies
a tension to the carrier web 22 that is greater than the tension
applied to the green tape material 20. In some embodiments, the
tension isolator applies a tension to the carrier web that is equal
to or greater than about 2 times the tension applied to the green
tape material, as the continuous tape material is moved from the
source 16 to the peeler 30. In some embodiments, the tension
isolator 28 applies a tension to the carrier web 22 that is at
least 20% greater than the tension applied to the green tape
material 20 and/or at least 25 millinewtons (mN) greater, such as
at least 100 mN greater, such as at least 200 mN greater. As may be
intuitive, tension as used herein generally refers to the
lengthwise or axial pulling apart of material and when given units
of force herein, tension refers to tensile force, and when given
units of stress, tension refers to tensile stress, and/or tension
herein may be given other units and refer to another related
parameter, such as pounds per linear inch or the metric
equivalent.
[0161] In the embodiment shown in FIG. 4, the tension isolator 28
may include a vacuum drum 25. As illustrated in FIG. 6, in one or
more embodiments, the vacuum drum 25 is rotated to move the
continuous tape material by a drive motor input 27, which is
connected to the vacuum drum by a bearing housing 29. As shown in
FIG. 7, the vacuum drum may include an outer surface including a
plurality of vacuum holes 7 disposed in a uniform distribution. The
vacuum holes 7 may be formed along a plurality of axial grooves 8
and/or radial grooves, which intersect one another at a vacuum hole
7. A vacuum is supplied to the vacuum drum 25 via a vacuum source
(e.g., a vacuum blower), which through the vacuum holes 7, grips
the carrier web 22, thereby facilitating tensioning the carrier
web, as described herein. In one or more embodiments, the
distribution of the vacuum holes 7 and the configuration of the
vacuum drum (including the diameter and vacuum force utilized)
apply or help to apply a uniform tension to the carrier web along
the width of the carrier web. Through this action and
configuration, the vacuum drum paces the velocity of the carrier
web (and thus the continuous tape material) as it travels through
the separation system 12. In one or more embodiments, the tension
isolator pulls the continuous tape material from the source along
the first tension zone 17. Any or some inconsistencies in the
delivery of the green tape material from the source 16 to the
peeler 30, such as a loose wind (which can result in cinching
during conveyance from the source to the peeler) do not or may not
affect the separation process. Vacuum drum 25 provides a bonding or
attracting force between the tape material (e.g. carrier web) and
the vacuum drum 25 in addition to normal force and friction that
are proportional to tension, thus increasing the bonding or
attracting force without necessarily increasing tension in the tape
material. At least because of this advantage, Applicants believe
that use of a vacuum drum to control the bonding or attracting
force between the tape material and a roller (i.e. the vacuum drum)
during the step of separating the green tape from the carrier web
is a unique and effective process for protecting and controlling
the shape of the green tape, which may be particularly delicate.
With that said, aspects of the present technology may be used to
create new sintered products, such as tapes that do have the
indicia of separation without use of a vacuum drum as disclosed
herein, such as repeating defects from rollers, changes in tape
thickness, shorter lengths of tape, etc.
[0162] In one or more embodiments, the tension isolator 28
increases tension in the continuous tape material (and more
particularly in the carrier web or mostly the carrier web) along
the second tension zone 19 as the continuous tape material is
conveyed to the peeler 30. In the embodiment shown in FIG. 4, the
separation system 12 includes a load controller 21 to maintain the
tension on the carrier web. In one or more embodiments, the load
controller 21 is also used to adjust the velocity of the uptake
reel 26 relative to the tension isolator 28.
[0163] In one or more embodiments, the peeler 30 is disposed
downstream from the tension isolator 28 and directs the carrier web
22 in a rewind direction A and directs the green tape material 20
in a downstream processing direction B that differs from the rewind
direction A, as shown in FIG. 8. In one or more embodiments, the
rewind direction A and the downstream processing direction form an
angle C that is greater than about 90 degrees (e.g., 95 degrees or
greater, 100 degrees or greater, 110 degrees or greater or about
120 degrees or greater).
[0164] In one or more embodiments, the peeler 30 includes a sharp
knife or edge to create a line of separation in the green tape
material, such as at or proximate to the vertex of the angle C,
shown as tip 31. In one or more embodiments, the sharp knife or
edge creates a line of separation in the green tape material, but
not the carrier web, just prior to a tip 31 or proximate to the tip
31, as shown in FIG. 8. In one or more embodiments, the tip has a
radius of about 0.05 inches or less (e.g., about 0.04 inches or
less, about 0.035 inches or less, about 0.03125 inches or less,
about 0.03 inches or less, or about 0.025 inches or less).
[0165] As continuous tape material passes over the tip 31, the tip
31 separates the carrier web 22 from the green tape material 20. In
one or more embodiments, the tip 31 separates the carrier web 22
from the green tape material 20 before directing the carrier web in
the rewind direction A and directing the green tape material in the
downstream processing direction B. In one or more embodiments, the
tip 31 separates the carrier web 22 from the green tape material 20
simultaneously with directing the carrier web 22 in the rewind
direction A and directing the green tape material 20 in the
downstream processing direction B.
[0166] As shown in FIG. 4, the separation system 12 includes an
uptake reel 26 for collecting the separated carrier web 22. In the
embodiment shown, an optional idle roller 23 may be used to further
control and maintain tension in the carrier web 22. In one or more
embodiments, sensors 15 may also be used to control and maintain
tension in the carrier web as the source 16 diameter decreases and
the uptake reel 26 diameter increases, as more continuous tape
material is conveyed through the separation system.
[0167] Another aspect of the support web removal station pertains
to a method for separating two materials (e.g., the green tape
material and the carrier web). In one or more embodiments, the
method includes feeding the continuous tape material 18 to the
tension isolator 28, applying tension to the carrier web 22 that is
greater than a tension applied to the green tape material 20 with
the tension isolator, and directing the carrier web to move in the
rewind direction and directing the green tape material in a
downstream processing direction that differs from the rewind
direction, as described herein. In one or more embodiments, the
method includes separating the carrier web from the green tape
material before directing the carrier web in a rewind direction and
directing the green tape material in the downstream processing
direction. In one or more embodiments, the method includes
separating the carrier web from the green tape material
simultaneously with directing the carrier web in the rewind
direction and directing the green tape material in the downstream
processing direction. As taught above, embodiments of this method
have the carrier web contacting the vacuum drum. In other
embodiments, tape materials may have carrier webs on both sides of
the tape, and elements of the separation station may be repeated
and used to remove both carrier webs.
[0168] In one or more embodiments, the method includes applying no
tension or substantially no or very little tension (as disclosed
above) to the green tape material. In one or more exemplary
embodiments, the method includes applying no tension or
substantially no or very little tension to the green tape material
as the continuous tape material moves from the source 16 to the
tension isolator 28 along the first tension zone 17. In one or more
exemplary embodiments, the method includes applying no tension or
substantially no or very little tension to the green tape material
as the continuous tape material moves from the tension isolator 28
to the peeler 30 along the second tension zone 19. In one or more
embodiments, the method includes applying no tension or
substantially no or very little tension to the green tape material
20 as the continuous tape 18 moves from the source 16 to the
tension isolator 28 (along the first tension zone) and to the
peeler 30 (along the second tension zone). In one or more
embodiments, the method includes applying tension to the carrier
web 22 that is at least two times greater than the tension applied
to the green tape material 20 (at any point along the separation
system 12). Selecting a carrier web with low elasticity may
facilitate having the carrier web bear a bulk of tension applied to
the tape material.
[0169] In one or more embodiments, the method includes applying no
additional tension to the green tape material, other than the
tension that is applied on the green tape material through the
application of tension on the carrier web 28. In such embodiments,
the carrier web may stretch due to such application of tension on
the carrier web, which in turn creates some tension on the green
tape material. In one or more exemplary embodiments, the method
includes applying no additional tension to the green tape material
as the continuous tape material moves from the source 16 to the
tension isolator 28 along the first tension zone 17. In one or more
exemplary embodiments, the method includes applying no additional
tension to the green tape material as the continuous tape material
moves from the tension isolator 28 to the peeler 30 along the
second tension zone 19. In one or more embodiments, the method
includes applying no additional tension to the green tape material
20 as the continuous tape 18 moves from the source 16 to the
tension isolator 28 (along the first tension zone) and to the
peeler 30 (along the second tension zone).
[0170] In one or more embodiments, the method for separating two
materials (i.e., the green tape material and the carrier web)
includes feeding the continuous tape material to the tension
isolator and applying a first tension to the carrier web, applying
a second tension to the carrier web that is greater than the first
tension, and directing the carrier web to move in a rewind
direction and directing the green tape material in a downstream
processing direction that differs from the rewind direction. In one
or more embodiments, applying a first tension comprises applying no
tension or little tension as disclosed herein. In one or more
embodiments, applying a first tensions comprises applying no or
little tension to the carrier web as the continuous tape material
moves from the source 16 to the tension isolator 28 along the first
tension zone. In one or more embodiments, the second tension is
about 2.5 PLI or less. For example, in one or more embodiments, the
tension applied to the carrier web 22 is about 2.4 PLI or less,
about 2.3 PLI or less, about 2.2 PLI or less, about 2.1 PLI or
less, about 2 PLI or less, about 1.8 PLI or less, about 1.6 PLI or
less, about 1.5 PLI or less, about 1.4 PLI or less, about 1.2 PLI
or less, or about 1 PLI or less. In one or more embodiments, the
first tension is equal to or less than about 50% (e.g., about 45%
or less, about 40% or less, about 35% or less, about 30% or less,
or about 25% or less) of the second tension.
[0171] In one or more embodiments, the method includes at least
partially sintering the green tape material (as will be discussed
in more detail herein related to the sintering station), after it
is separated from the carrier web 22. In one or more embodiments,
the method includes spooling the carrier web 22 onto an uptake reel
26, after the carrier web 22 is separated from the green tape
material 20. In one or more embodiments, the method includes
continuously maintaining the tension on the carrier web 22 along
the second tension zone and until the carrier web is spooled onto
the uptake reel.
Binder Removal Station
[0172] As noted above regarding FIG. 3, system 10 includes a
heating station configured to remove binder material from green
tape 20 which, in at least some embodiments, is actively and
independently heated separately from the sintering stations. In
other embodiments, such as with firing of bisque tapes as disclosed
herein, there may be no heating station. Applicant believes that
actively heating a station dedicated to binder removal with its own
controllable heat source, independent of heaters within the
sintering furnace, allows for greater control of the binder removal
process, reducing likelihood of combustion of volatiles in the
binder of the green tape, which is particularly beneficial for wide
green tapes (e.g., at least 5 mm, at least 10 mm, at least 30 mm,
at least 50 mm). Other embodiments include passively-heated binder
removal stations disclosed herein, where the stations use heat
emitted from an adjoining sintering furnace.
[0173] According to an exemplary embodiment, as shown in FIG. 3, a
binder removal station 34 receives green tape 20 from separation
station 12, and green tape 20 then advances through the binder
removal station 34. Referring now to FIG. 9, a detailed view of
binder removal station 34 of system 10 is shown and described in
more detail.
[0174] As discussed above, the green tape 20 includes grains of an
inorganic material bound by a binder as disclosed herein, such as
an organic binder. The binder removal station 34 receives the green
tape 20 and prepares the green tape 20 for sintering by chemically
changing the binder and/or removing the binder from the green tape
20, leaving the grains of the inorganic material, to form
self-supporting, unbound tape 36, which may be moved in the
processing direction 14 into sintering station 38, as discussed in
more detail below. According to an exemplary embodiment, at an
instant (i.e. a single moment in time) the green tape 20
simultaneously extends toward, into, through, within, adjacent to,
and/or away from the station 34. Accordingly, as will be
understood, the tape material being processed in system 10
simultaneously includes the green tape 20 which is continuously
connected to unbound tape 36, as the tape material traverses binder
removal station 34.
[0175] According to an exemplary embodiment, the binder of the
green tape 20 may be a polymer binder and the binder is chemically
changed and/or removed from the green tape 20 by heating the binder
to burn or char the binder. According to an exemplary embodiment,
the binder removal station 34 chars or burns at least most of the
organic binder in terms of weight from the first portion of the
green tape 20 without sintering the grains of the inorganic
material, which can be measured by weighing the green tape before
binder removal at the station 34 as well as the inorganic material
prior to forming the green tape, then weighing the unbound tape 36
following operation of the binder removal station 34 and comparing
differences. If remnants of the binder remain, such as carbon,
Applicant believes that subsequent sintering, at higher
temperatures, may generally remove those remnants. In other
contemplated embodiments, the binder may be chemically removed,
such as formed from a material selected to chemically react with
another material (e.g., catalyst, gas) delivered to the green tape
at a binder removal station prior to sintering. In still other
contemplated embodiments, the binder may be evaporated or otherwise
vaporized and outgassed from the green tape 20 at a station prior
to sintering.
[0176] Still referring to FIG. 9, according to an exemplary
embodiment, the binder removal station 34 comprises an active
heater 5120 to char or burn at least most of the organic binder
from the green tape 20 as the green tape 20 interfaces with the
binder removal station 34 to form the unbound tape 36 (e.g., by
reducing weight of the portion of the green tape 20 that is not
inorganic material to be sintered by greater than 50%, such as
greater than 70%, such as greater than 90%; by reducing weight of
the overall green tape 20 by greater than 30%, such as greater than
50%). The active heater 5120 provides heat energy to the green tape
20 to burn out the binder. In some embodiments, the heater 5120 is
or includes an electrical heating element, such as an inductive or
resistive heating element. In other embodiments, the heater 5120 is
or includes a combustion heating element, such as a gas heating
element. In still other embodiments, the heater 5120 is or includes
a microwave and/or a laser or other heating element. Such heating
elements may also be used in the sintering station 38, but heat to
different temperatures as disclosed herein.
[0177] According to an exemplary embodiment, the active heater 5120
of the binder removal station 34 includes heating zones, such as
zones 5120A, 5120B, 5120C, 5120D such that the rate of heat energy
received by the green tape 20 increases as the green tape 20
advances through the binder removal station 34. In some
embodiments, the rate of heat energy received by the green tape 20
increases in a nonlinear manner, such as slowly increasing at
first, as the binder degrades and emits combustible gaseous
byproducts, and then faster as the potential for the green tape 20
catching fire is reduced. This heat zone approach and more
specifically the non-linear approach may be particularly useful for
sintering of tapes, as disclosed herein, which may travel a
manufacturing line, such as system 10, at a constant rate.
According to an exemplary embodiment, temperatures experienced by
the green tape 20 in the binder removal station 34 may be at least
200.degree. C., such as at least 250.degree. C., and/or below a
sintering temperature for the inorganic grains carried by the green
tape 20, such as less than 1200.degree. C., such as less than
900.degree. C. In contemplated embodiments, for at least some
materials disclosed herein, the binder removal station 34 may
sinter, at least to some degree, inorganic material of the tape,
such as possibly bonding individual grains to one another, which
may increase tensile strength of the tape.
[0178] According to an exemplary embodiment, the binder removal
station 34 blows and/or draws gas over and/or under (e.g., over and
under) the green tape 20 as the green tape 20 advances through the
binder removal station 34. In some embodiments, the heater 5120 may
provide a flow of hot air to communicate some or all of the heat
energy to the green tape 20, as may be delivered through an array
of nozzles through a wall from a plenum, or through a porous wall
material. In other embodiments, flow of the gas is facilitated by
fans or pumps adjoining the binder removal station 34, such as fan
5122 shown in FIG. 9. Tanks of pressurized gas may also be used as
sources to supply gas to be blown over the tape. In some
embodiments, the gas is air. In other embodiments, the gas is an
inert gas, such as argon.
[0179] In some embodiments, gas is blown and/or drawn over both the
topside and underside of the green tape 20, while in other
embodiments, the gas is directed only over the topside or the
underside. In some such embodiments, the green tape 20 is directly
supported by a gas bearing and/or an underlying surface and moves
relative to that surface. For example, the green tape 20 may slide
along and contact an underlying surface, such as a surface made of
stainless steel. In some embodiments the gas is heated to a
temperature above room temperature before blowing or drawing it
over the tape, such as to at least 100.degree. C., which Applicants
have found may help prevent thermal shock of the green tape 20,
which may influence properties of resulting sintered material, such
as providing increased strength or flatness due to fewer sites of
surface irregularities and stress concentrations.
[0180] Actively blowing or drawing gas over the green tape 20,
especially air or gas containing oxygen, may be counterintuitive to
those of skill in the art because one might expect the oxygen to
fuel and promote the tape catching fire, which could distort the
shape of the green tape 20 and/or otherwise harm quality of the
green tape 20 as tape 20 traverses station 34. However, Applicant
has found that as the green tape 20 is conveyed through the binder
removal station 34, blowing and/or drawing gas, including air in
some embodiments, over the green tape 20 actually helps the tape
not to catch fire. For example, Applicant has found that while the
binder is removed and/or charred by the binder removal station 34
without catching fire, that the tape catches fire when moving at
the same rate through the station 34 if air is not blown over the
green tape 20. Applicant contemplates that risk of catching the
green tape 20 on fire may also be reduced and/or eliminated by
moving the green tape 20 slower through the binder removal station
34, further spacing apart the heat zones 5120A, 5120B, 5120C,
5120D, using flame retardants in the binder and increasing
ventilation of the binder removal station 34, and/or combinations
of such technologies.
[0181] While gas may be actively blown and/or drawn over the green
tape 20 and/or the unbound tape 36, Applicant has found that the
unbound tape 36 may be particularly susceptible to damage from
vibration and/or out-of-plane bending depending upon how the gas
flows. Accordingly, in some embodiments, the gas flowing through
the binder removal station 34 is and/or includes laminar flow. The
flow of the air may be diffused and/or may not be directed to the
unbound tape 36. In some embodiments, a gas source or motivator
(e.g., fan, pump, pressurized supply) delivers at least 1 liter of
gas per minute through the binder removal station 34, such as
through the passage 5128 (see FIG. 10).
[0182] According to some embodiments, the green tape 20 advances
horizontally, not vertically through the binder removal station 34.
Orienting the tape horizontally may help control airflow through
the binder removal station 34, such as by reducing a "chimney
effect," where hot gasses rise and pull too much air through the
binder removal station 34, vibrating the unbound tape 36. Air
pumps, fans, and surrounding environmental air conditions (e.g.,
high temperatures) offset and/or control the chimney effect without
horizontally orienting the green tape 20 through the binder removal
station 34 in other contemplated embodiments.
[0183] According to an exemplary embodiment, the unbound tape 36 is
under positive lengthwise tension as the green tape 20 advances
through station 34. Tension in the green tape 20 may help hold the
green tape 20 in a flat orientation, such as if the green tape 20
subsequently passes into another station of the manufacturing
system for further processing, such as a sintering station 38.
Without the binder (e.g., following binder removal in station 34),
the unbound tape 36 may be weaker than the green tape material 20,
such as having lesser ultimate tensile strength, such as half or
less, such as a quarter or less. According to an exemplary
embodiment, lengthwise tension (i.e. tensile stress) in the unbound
tape 36 is less than 500 grams-force per mm.sup.2 of cross section.
Applicant believes the green tape 20 is substantially more bendable
than the unbound tape 36 such that a minimum bend radius without
fracture of the green tape 20 is less than half that of the unbound
tape 36 (e.g., less than a quarter, less than an eighth), when
measured via ASTM standards, see E290, where bend radius is the
minimum inside radius the respective portions of the green tape 20
can bend about a cylinder without fracture.
[0184] In at least some embodiments, following processing through
the binder removal station 34, the unbound tape material 36 moves
into sintering station 38 (discussed in more detail below), which
at least partially sinters the inorganic material of the unbound
tape 36 to form sintered tape 40. Accordingly, for continuous
processing, at an instant the green tape 20 is continuously
connected to sintered tape 40 by way of the unbound tape 36.
[0185] In some such embodiments, binder removal station 34 is close
to the sintering station 38 such that distance therebetween is less
than 10 m (e.g., less than 10 mm, less than 2.5 cm, less than 5 cm,
less than 10 cm, less than 25 cm, less than 100 cm, less than 5 m,
etc. between the outlet opening of the binder removal station 34
and the entrance opening 106 (see FIG. 12) of the sintering station
38) thereby mitigating thermal shock that unbound tape 36 may
experience in the gap between station 34 and station 38, which may
influence properties of resulting sintered material, such as
providing increased strength or flatness due to fewer sites of
surface irregularities and stress concentrations. In contemplated
embodiments, binder removal station 34 is in direct contact with
and adjoins the sintering station 38 and/or is under a common
housing therewith, however in at least some such embodiments an
intermediate vent draws away fumes or other byproducts of the
binder removal.
[0186] Referring now to FIG. 10, the binder removal station 34
includes walls 5126 defining a passage 5128 having inlet and outlet
openings 5130, 5132 on opposing ends of the passage 5128. The
passage has a length L between the inlet and outlet openings 5130,
5132, which in some embodiments is at least 5 cm, such as at least
10 cm, and/or no more than 10 m. According to an exemplary
embodiment, the outlet opening 5132 and/or the inlet opening 5130
is narrow and elongate, such as having a height H and a width W
orthogonal to the height H where the height H is less than half the
width W, such as less than a fifth the width W, such as less than a
tenth the width W. In some such embodiments, the height H is less
than 5 cm, such as less than 2 cm, such as less than 1 cm, and/or
at least greater than a thickness of green tape 20 to be processed
thereby, such as at least greater than thicknesses of green tape
disclosed herein, such as at least greater than 20 .mu.m. Applicant
has found that having a narrow opening(s) improves performance of
the binder removal station 34 by limiting circulation of gas (e.g.,
ambient airflow) at the inlet and outlet openings 5130, 5132. In
some embodiments, the passage 5128 is straight, while in other
embodiment the passage is gently arcing, such as having a radius of
curvature of greater than 1 m, where the arcing and corresponding
curvature of the tape may help shape or flatten the tape.
[0187] Referring to FIG. 11, a method of processing tape 5210
includes a step of advancing tape through a manufacturing system
5212 (e.g., binder removal station 34 or other manufacturing
systems disclosed herein), such as where the tape includes a first
portion having grains of an inorganic material bound by a binder
(e.g., green tape 20). The method further includes a step of
preparing the tape for sintering 5214 by forming a second portion
of the tape (e.g., unbound tape 36) at a station of the
manufacturing system by chemically changing the binder and/or
removing the binder from the first portion of the tape, leaving the
grains of the inorganic material, thereby forming a second portion
of the tape.
[0188] In some such embodiments, the step of preparing the tape for
sintering 5214 further comprises charring or burning at least most
of the binder from the first portion of the tape (e.g., as
discussed above) with or without contemporaneously sintering the
grains of the inorganic material. In some embodiments, the station
of the manufacturing system is a first station and the method of
processing 5210 further comprises steps of receiving the second
portion of the tape at a second station 5218, and at least
partially and/or further sintering the inorganic material of the
second portion of the tape 5220 at the second station to form a
third portion of the tape.
[0189] In some embodiments, the method of processing 5210 further
comprises positively tensioning the second portion of the tape as
the tape advances 5212. In some such embodiments, positively
tensioning is such that lengthwise tension (i.e. tensile stress) in
the second portion of the tape is less than 500 grams-force per
mm.sup.2 of cross section. In some embodiments, the method of
processing 5210 further comprises blowing and/or drawing gas over
the tape while preparing the tape for sintering 5214. In some
embodiments, the step of advancing the tape 5212 further comprises
horizontally advancing the tape through the station, and/or
directly supporting the tape by a gas bearing and/or an underlying
surface and moving the tape relative to that surface and/or
relative to the opening 5128.
Example of Binder Removal
[0190] Applicant has used a binder burn-out furnace similar to
binder removal station 34 to remove binder from green tape prior to
sintering. In one example, the green tape was tape cast zirconia
ceramic grains loaded with polymer binder forming a ribbon of about
42 mm wide and about 25 .mu.m thick. The green tape was feed
through a horizontal six-hot-zone binder burnout furnace at 20
inches per minute. The binder burnout furnace was set at
325.degree. C. inlet to 475.degree. C. outlet with 0 to 25.degree.
C. increasing degree increments for the other four hot zones. About
7.5 liters per minute of air flow at temperatures 0 to 250.degree.
C. was also provided. The air flow was divided between both sides
of the binder burn-out furnace. The furnace was 36 inches long and
had an 18-inch hot zone.
Sintering Station
[0191] Referring to FIG. 12 through FIG. 20, sintering station 38
is shown and described in more detail. In general, following
removal of binder material from green tape 20 within binder removal
station 34, unbound tape 36 moves into sintering station 38.
[0192] In at least one specific embodiment, sintering station 38
includes a sintering furnace 100. Sintering furnace 100 includes an
insulated housing 102. In general, insulated housing 102 includes a
plurality of internal walls that define a channel 104 that extends
through sintering furnace 100 between an entrance, shown as
entrance opening 106, and an exit, shown as exit opening 108.
Binder removal station 34 is located adjacent to entrance opening
106 such that green tape material 20 passes through binder removal
station 34 producing unbound tape material 36 as described above.
Unbound tape material 36 passes into entrance opening 106 and
through channel 104. While within channel 104, heat generated by a
heater (explained in more detail below, and above with regard to
different types of heating elements) causes sintering of unbound
tape 36 to form sintered tape 40, and sintered tape 40 passes out
through exit opening 108 for further processing or uptake as shown
in FIG. 3. Depending on the temperature profile that unbound tape
36 is exposed to during sintering, upon exiting sintering furnace
100, tape 40 may be fully sintered or partially sintered. Whether
tape 40 is partially sintered or fully sintered, the porosity of
tape 40 is less than the porosity of green tape 20 due to the
sintering that occurs within furnace 100. Similarly, in some
embodiments, the width of tape 40 is less than the width of green
tape 20. In some such and yet other embodiments, shrinkage of
unbound tape 36 may be controlled during sintering such that
thickness, width and/or length of tape 40 is less than the
thickness of green tape 20.
[0193] As can be seen in FIG. 12, and in contrast to typical
discreet piece based sintering systems, unbound tape 36 is a
continuous length of material that extends completely through
furnace 100. In this arrangement, a single continuous length of
unbound tape 36, extends into entrance 106, through channel 104 and
out of exit 108. As will be understood, because unbound tape 36 is
continuous through furnace 100, its left edge, its right edge and
its centerline (e.g., a longitudinal line located parallel to and
equidistance from the left edge and the right edge) also or may
also extend the entire distance through furnace 100 between
entrance 106 and exit 108. For reference, FIG. 14, shows the edges
referenced above, as edges 130 and 132, after exiting sintering
furnace 100. This relationship between the continuous tape 36 and
furnace 100 is believed to be unique to the roll-to-roll sintering
process discussed herein and is different from the physical
arrangement of tunnel kiln processing for sintering in which
discreet pieces of material move through a furnace supported by a
setter board that moves through the furnace with the piece that is
being sintered. For example, in some embodiments, the tape slides
along and/or relative to a surface(s) (e.g., lower surface 126)
through channel 104 of furnace 100, and is not carried on a setter
or conveyor, which may reduce bonding to and adhesive wear of the
tape associated with setters and static versus dynamic friction and
adhesion.
[0194] As noted above, Applicant has found that a high level of
horizontality of channel 104 and/or of unbound tape 36 within
channel 104 reduces the effect of turbulent air flow on tape 36
during sintering. As shown in FIG. 12, channel 104, entrance 106,
and exit 108 lie in a substantially horizontal plane. In specific
embodiments, the path defined through the central axes of channel
104, entrance 106, and exit 108 defines a substantially horizontal
plane and/or gradual arc or curve (e.g., having a radius of
curvature of at least 1 m). Similarly, in such embodiments, unbound
tape 36 may also lie within a substantially horizontal plane and/or
gradual arc or curve within channel 104 (e.g., upper surface 124
and/or lower surface 126 of tape 36, shown in FIG. 13, lie in a
substantially horizontal plane). As used herein a substantially
horizontal plane of tape 36 and defined by channel 104, entrance
106, and exit 108 is one that forms angle of 10 degrees or less
relative to a horizontal reference plane. In other specific
embodiments, channel 104, entrance 106, and exit 108 and/or tape 36
within channel 104 lie in an even more horizontal plane, such as a
plane forming an angle of 3 degrees or less relative to a
horizontal reference plane, and more specifically at an angle of 1
degree or less relative to a horizontal reference plane. In other
embodiments, the channel 104 is not so oriented, and the
corresponding sintered tape may have indicia (e.g., rolling surface
mounds or bumps) associated with the "chimney effect" or irregular
heating, such as if air flow through the channel 104 is
turbulent.
[0195] To further control or limit turbulent air flow that the tape
material of system 10 is exposed to during traversal of system 10,
binder removal station 34 may be positioned relative to sintering
station 38 in manner that maintains the tape material (e.g., green
tape material 20 within binder removal station and unbound tape
material 36 within sintering station) in a substantially horizontal
position as tapes 20 and 36 traverse binder removal station 34 and
sintering station 38. In such embodiments, similar to the
horizontal positioning of sintering channel 104, binder removal
station 34 is or may be also oriented in a substantially horizontal
position, such as where openings 116, 118 are aligned to form a
line therebetween that is within 10 degrees of horizontal.
[0196] In such embodiments, binder removal station 34 includes a
binder burn out furnace 110. Binder burn out furnace 110 includes
an insulated housing 112. In general, insulated housing 112
includes a plurality of internal walls that defines a channel 114
that extends through binder burnout furnace 110 between an entrance
opening 116, and an exit opening 118.
[0197] As shown in FIG. 12, referring to binder burn out furnace
110, channel 114, entrance opening 116, and exit opening 118 lie in
a substantially horizontal plane. In specific embodiments, the path
defined through the central axes of channel 114, entrance 116, and
exit 118 defines a substantially horizontal plane. Similarly, in
such embodiments, green tape 20 may also lie within a substantially
horizontal plane within channel 114. As used herein a substantially
horizontal plane of green tape 20 and of channel 114, entrance
opening 116, and exit opening 118 is one that forms an angle of 10
degrees or less relative to a horizontal reference plane. In other
specific embodiments, channel 114, entrance opening 116, and exit
opening 118 and/or green tape 20 within channel 114 lie in an even
more horizontal plane, such as a plane forming an angle of 3
degrees or less relative to a horizontal reference plane, and more
specifically at an angle of 1 degree or less relative to a
horizontal reference plane. In still other embodiments, these
features may not be so horizontally aligned.
[0198] In addition to maintaining horizontality of green tape 20
and unbound tape 36 within binder burnout furnace 110 and sintering
furnace 100, respectively, binder burnout furnace 110 (also called
binder removal station) and sintering furnace 100 are aligned
relative to each other such that unbound tape 36 maintains a
horizontal position as unbound tape 36 transitions from binder
burnout furnace 110 to sintering furnace 100. Applicant has found
that at this transition point, unbound tape 36 is particularly
susceptible to deformation or breakage due to various forces (such
as force caused by turbulent airflow) because with most of the
organic binder removed, the unsintered inorganic grains of unbound
tape 36 are held together by relatively weak forces (e.g., Van der
Walls forces, electrostatic interaction, a small amount of
remaining organic binder, frictional interaction/engagement between
adjacent particles, low levels of inorganic carried in the binder,
plasticizer, liquid vehicle, perhaps some particle-to-particle
bonding etc.), and thus, even relatively small forces, such as
those cause by turbulent airflow interacting with unbound tape 36,
can cause deformation or breakage.
[0199] Thus, as shown in FIG. 12, to limit turbulent airflow,
channel 114 of binder burnout furnace 110 is aligned with channel
104 of sintering furnace 100 in the vertical direction. Following
the tape path through sintering furnace 100 and binder burnout
furnace 110, green tape 20 moves in the horizontal direction from
the input roll (shown in FIG. 3) into binder burnout entrance 116,
through binder burnout channel 114 and out of binder burnout exit
118. While within channel 114, heat generated by the heater of
furnace 110 chemically changes and/or removes at least a portion of
the organic binder material of green tape 20, called "burnout." In
addition, the relative positioning of binder burnout furnace 110
and sintering furnace 100 is such that unbound tape 36 moves into
sintering furnace 100 from binder burnout furnace 110 all while
remaining in a horizontal position or a generally horizontal
position as described above. Thus, the vertical alignment between
channels 104 and 114 allows unbound tape 36 to remain in the
substantially the same horizontal plane (i.e., without shifting up
or down between furnaces 110 and 100) as the tape material
traverses both furnaces 100 and 110, at least in some
embodiments.
[0200] Applicant has determined that a benefit of horizontal binder
removal and/or horizontal sintering becomes more important as the
width of the tape material increases because wider tape materials
are more susceptible to airflow turbulence-based deformation. Thus,
Applicant believes that the horizontal arrangement of sintering
furnace 100 and/or binder burnout furnace 110 allows for production
of wider and/or longer sintered tape materials without significant
deformation or breakage believed not achievable using prior
systems.
[0201] Referring to FIG. 13 and FIG. 14, in addition to horizontal
positioning of binder burnout furnace 110, of the sintering furnace
100 and of the tape materials (e.g., green tape 20 and unbound tape
36) within the furnaces, Applicant has also discovered that
turbulent airflow can be limited by providing sintering channel 104
with a relatively low height dimension (which in turn relates to a
relatively low clearance relative to unbound tape 36). Applicant
has discovered that turbulent airflows, that may otherwise be
experienced due to the very hot air within channel 104, can be
limited by decreasing the volume of the region within which thermal
gradients can develop and within which such thermal gradients can
cause air to move.
[0202] As shown in FIGS. 13 and 12, channel 104 is defined in part
by a horizontal, and generally upwardly facing surface 120 which
defines at least a portion of the lower surface of channel 104.
Similarly, channel 104 is also defined in part by a horizontal, and
generally downwardly facing surface 122 which defines at least a
portion of the upper surface of channel 104. A first gap, shown as
G1, is the vertical distance between upwardly facing surface 120
and downwardly facing surface 122, and G2 is the vertical distance
or clearance between downwardly facing surface 122 and upper
surface 124 of unbound tape 36.
[0203] As noted above, in various embodiments, G1 and G2 are
relatively small such that turbulent air flow is limited, but G1
and G2 should generally be large enough that various processing
steps (e.g., threading of channel 104 for example) are possible. In
various embodiments, G2 is less than 0.5 inches (less than 12.7
mm), specifically is less than 0.375 inches (less than 9.5 mm) and
more specifically is 0.25 inches (about 6.35 mm). As will be
understood, G1 is generally equal to G2 plus the thickness T1 of
unbound tape 36. Thus, in various embodiments, because T1 is
relatively low, e.g., between 3 microns and 1 millimeter, G1 is
less than 1 inch (less than 25.4 mm), specifically less than 0.75
inches (less than 19 mm), and for thin tape materials may be less
than 0.5 inches (less than 12.7 mm), and for very thin tape
materials may be less than 0.375 inches (less than 9.5 mm).
[0204] FIG. 14 shows exit 108 of sintering furnace 100 showing the
small clearance, G2, relative to tape 40 according to an exemplary
embodiment. In various embodiments, G1 and G2 may represent the
maximum gap distances between the relevant surfaces and in another
embodiment, G1 and G2 may represent the average gap distances
between the relevant surfaces measures along the length of channel
104.
[0205] In specific embodiments, surface 120 and/or surface 122 are
also substantially horizontal surfaces (as described above) that
extend between entrance 106 and exit 108 of furnace 100. In such
embodiments, surfaces 120 and 122 therefore define a substantially
horizontal channel 104. In some specific embodiments, surfaces 120
and/or 122 may be flat, planar horizontal surfaces extending the
entire distance between entrance 106 and exit 108 of furnace 100.
In other specific embodiments, surfaces 120 and/or 122 may be
gradually arcing or curving as described above, as may also be the
case with the binder removal station. In specific embodiments,
surfaces 120 and/or 122 are substantially horizontal such that the
surfaces form an angle less than 10 degrees, specifically less than
3 degrees and even more specifically less than 1 degree relative to
the horizontal reference plane.
[0206] As shown in FIG. 13, a lower surface 126 of unbound tape 36
is in contact with upwardly facing surface 120 such that lower
surface 126 of unbound tape 36 slides along or relative to upwardly
facing surface 120, as unbound tape 36 advances through furnace
100. In particular embodiments, the sliding contact between lower
surface 126 and upwardly facing surface 120 during sintering
creates or may create various longitudinal features (e.g.,
longitudinally extending marks, troughs, ridges, etc.) formed in
lower surface 126 but not on the upper surface 124. Therefore, in
specific embodiments, the surface features on lower surface 126 are
different from those of upper surface 124 which is not in contact
with an opposing surface during sintering. In particular, this
sliding contact is substantially different from the arrangement in
some firing processes, such as tunnel kiln processes, in which a
ceramic material is placed on a setter board and both move together
through the sintering furnace. In specific embodiments, surfaces
120 and 122 are or comprise alumina, such as inner surfaces of an
alumina tube that defines channel 104.
[0207] In addition the positional arrangements and airflow control
arrangements discussed above, Applicant has also found that control
of the temperature profile through furnace 100, that unbound tape
36 is exposed to, is important to limit tape deformation or
breakage, which Applicant has discovered may occur if the temperate
rise is too fast (e.g., sintering rate is too fast or over too
short a distance in the tape). In general referring to FIG. 15,
furnace 100 may include a plurality of independently controlled
heating elements 140 positioned to deliver heat to channel 104 in
order to cause sintering of unbound tape 36 as tape 36 traverses
furnace 100. While the maximum and minimum sintering temperatures
will vary at least in part based on the type of inorganic material
grains carried by tape 36, in general, heating elements 140 are
configured to generate a temperature of at least 500 degrees C.
along at least a portion of channel 104. In some embodiments, for
example for sintering ThO.sub.2 (thoria) and/or TiO.sub.2
(titania), channel 104 may be heated to maximum temperatures above
3100 degrees C. There are some materials, e.g., carbides, tungsten,
that have melting points above 3200 degrees, and in some such
embodiments, the temperature range generated by heaters 140 is
between 500 degrees C. and a higher temperature, e.g., 3500 degrees
C., or 3600 degrees C. In specific embodiments, heating elements
140 may be U-shaped molybdenum disilicide heating elements and/or
other heating elements disclosed herein.
[0208] In general, each heating element 140 may be under the
control of a control system 142 which is configured (e.g.,
physically arranged, programmed, etc.) to independently control
individual heating elements 140 of the furnace 100 to generate a
temperature profile along the length of channel 104 to provide the
desired level of sintering in sintered tape 40, while limiting
deformation during sintering. In some embodiments, control system
142 may be in communication with one or more temperature sensors
144, which detects temperature within channel 104. In such
embodiments, control system 142 may control heating elements 140
based on an input signal received from sensor 144 such that a
desired temperature profile is maintained during continuous
sintering of continuous unbound tape 36. In some embodiments,
control system 142 may also receive input signals indicative of
tape movement speed, position, shrinkage, and tension and control
temperature and/or movement speed based on these signals or other
signals, which may be related to these or other tape
properties.
[0209] As will be demonstrated in relation to the sintering furnace
examples set forth below, Applicant has discovered that application
of a sintering temperature profile along the length of channel 104
is or may be important to maintaining a low or controlled level of
deformation in the tape material during sintering. In particular,
Applicant has discovered that if the rise of temperature that
unbound tape 36 is exposed to during sintering is too great (e.g.,
the slope of the temperature profile is too steep), unacceptably
high levels of stress are or may be formed within tape 36 as the
material sinters and shrinks, which in turn results in out of plane
deformation in tape 36, such as that shown in FIG. 2. In
particular, Applicant has discovered that by controlling stresses
at edges 130 and 132 and/or along the centerline of tape 36 during
sintering, deformation of tape 36 during sintering can be
controlled. A similar potentially deleterious effect on tape 36 may
be experienced if the transition from the heated portions of system
10 to the room temperature portions of system 10 (e.g., upon exit
from furnace 100) occurs too sharply. With that said, technology of
the present application may be used to sinter tape without such
temperature control or profile, where the resulting new tape or
other sintered articles may have such characteristic deformation or
other defects.
[0210] Referring to FIG. 16 and FIG. 17, temperature profiles 160
and 170 generated by heating elements 140 along the length of
sintering channel 104 is shown according to exemplary embodiments.
Referring to FIG. 16, temperature profile 160 shows that the
temperature within channel 104 generally increases along the length
of channel 104 in the processing direction 14. Profile 160 includes
at least three sections: a first section 162 representing the
temperature within the region of channel 104 adjacent to entrance
opening 106; a second section 164 representing the temperature
along the majority (e.g., at least 50%, at least 75%, etc.) of the
length of channel 104; and a third section 166 representing the
temperature within the region of channel 104 adjacent to exit
opening 108.
[0211] As shown in FIG. 16, the average slope of first section 162
is greater than the average slope of second section 164 showing a
relatively rapid increase in temperature within channel 104
adjacent the entrance opening 106. The average slope of second
section 164 is relatively low (and lower than that of first section
162). The low average slope of second section 164 represents the
gradual rise in temperature that tape 36 experiences as it moves
along most of the length of channel 104. As will be discussed
below, this gradual rise is selected to maintain stresses within
tape 36 below determined thresholds that maintain deformation below
the desired level. The average slope of third section 166 is a
negative slope representing the cool down section within channel
104 adjacent exit opening 108 which limits thermal shock
experienced by tape 36 upon exit from furnace 100.
[0212] In various embodiments, the gradual temperature rise
represented by the low slope of section 164 may be achieved by
controlling the rate of temperature increase along the length of
channel 104. In various embodiments, as represented by the x-axis
in the plot of FIG. 16, the length of channel 104 may be relatively
large such as at least 1 meter, at least 50 inches, at least 60
inches or more. In the specific sintering furnace modeled and shown
in FIG. 16, the heated channel 104 is 64 inches.
[0213] In various embodiments, profile 160 is shaped to maintain an
acceptably low level of compressive stress within tape 36 during
sintering such that undesirable deformation is avoided. Applicant
has discovered that tape deformation, if not controlled as
discussed herein, is a challenge particularly for wide tape
materials and high throughput sintering systems. In particular,
wider tapes are more susceptible to this type of deformation, and
in addition, width wise deformation makes or may winding on uptake
reel difficult or impossible. With that said, aspects of the
presently disclosed technology (e.g., carrier separation, tension
control, binder removal, etc.) may be practiced and used to create
new materials and products without the temperature profiles, such
as where resulting products are narrower and/or have defects or
deformation characteristic of such processing.
[0214] Thus, in various embodiments, profile 160 is shaped such
that compressive stress at the left edge 130 and/or right edge 132
of unbound tape 36 during sintering remains below an edge stress
threshold and that compressive stress at a centerline of the
unbound tape 36 during sintering remains below a centerline stress
threshold. In general, the edge stress threshold and the centerline
stress threshold are defined as the compressive stresses above
which unbound tape 36 experiences out of plane (length-width plane)
deformation of greater than 1 mm during sintering. Applicant has
discovered that for at least some materials and tape widths, out of
plane deformation can be limited to below 1 mm during sintering by
maintain the edge compressive stresses and centerline compressive
stresses below thresholds of 100 MPa, specifically 75 MPa and more
specifically 60 MPa. In a specific embodiment, Applicant has
discovered that for at least some materials and tape widths, out of
plane deformation can be limited to below 1 mm during sintering by
maintaining centerline compressive stresses below thresholds of 100
MPa, specifically 75 MPa and more specifically 60 MPa, and by
maintaining edge stresses below thresholds of 300 MPa, specifically
250 MPa and more specifically 200 MPa.
[0215] In a specific embodiment, the slope of sections 162 and 166
may be controlled to provide for particularly low tape stresses on
entry to and exit from furnace 100. In one such embodiment, control
system 142 is configured to control the temperature profile within
sections 162 and 166 in combination with control of the speed of
tape through furnace 100. In such embodiments, this combination of
controlling temperature within sections 162 and 166, coupled with
speed control, give a uniform sintering shrinkage (strain) and thus
a low stress and low deformation within tape 36 during
sintering.
[0216] Referring to FIG. 17, another exemplary temperature profile
170 is shown projected along a view of channel 104. As shown,
profile 170 shows an increase to the maximum temperature at zone
172 over approximately at least 75% of the total length of channel
104. In particular embodiments, sintering furnace 100 can be can be
made of a high thermal conductivity material (such as steel or high
conductivity ceramic) to lower temperature gradients in the cross
web (tape/sheet) width direction. As shown in FIG. 17, there is low
or no temperature variance in the width direction. As will be
generally understood, the temperature profile for a particular
sintering system will be based on a number of factors including the
material type, inorganic particle size, particle density, particle
size distribution, porosity, porosity size, porosity size
distribution, the sintering atmosphere, the stress
thresholds/allowable deformation for the part as discussed above,
length of the channel 104, throughput speed, etc. as well as
desired outcome.
[0217] Referring to FIG. 18, another embodiment of sintering
station 38 is shown according to an exemplary embodiment. In this
embodiment, sintering station 38 includes two furnaces 180 and 182
positioned in series with each other. In general, furnaces 180 and
182 are substantially the same as furnace 100 discussed above,
except that, in at least some embodiments, the temperature profile
of furnace 180 is different than the temperature profile within
furnace 182. In this arrangement, unbound tape 36 enters entrance
106 of furnace 180. Within furnace 180, unbound tape 36 is
partially sintered forming partially sintered tape 184 which leaves
furnace 180 through exit 108. Then partially sintered tape 184
enters second furnace 182 through entrance 106, and additional
sintering occurs along the length of channel 104 of furnace 182
such that sintered tape 40 exits furnace 182 through exit 108 for
reel uptake as discussed above.
[0218] In various embodiments, each furnace 180 and 182 includes a
plurality of independently controllable heating elements such that
a different and independent temperature profile can be formed in
each furnace 180 and 182. In some embodiments, utilizing two
thermally isolated furnaces, such as furnace 180 and 182, may
provide more precise control of the temperature profiles that the
tape material is exposed to during sintering, as compared to a
single long furnace having the same channel length as the combined
channel length of furnaces 180 and 182. In other contemplated
embodiments, the tape can be moved back through the same furnace,
but along a different path and/or exposed to a different
temperature profile for additional sintering.
[0219] In addition, in some embodiments, application of
differential tension between furnace 180 and 182 may be desirable.
In such embodiments, a tension control system 186 is located along
the sintering path defined by the channels 104 of furnaces 180 and
182. In specific embodiments, tension control system 186 is located
between furnaces 180 and 182 and applies tension to partially
sintered tape 184 such that the tension with tape 184 within second
furnace 182 is greater than the tension with unbound tape 36 within
furnace 180. In various embodiments, increasing tension in the
second sintering furnace may be desirable to provide for improved
flatness or deformation reduction during the final or subsequent
sintering of furnace 182. In addition, this increased tension may
be suitable for application to partially sintered tape 184 because
the partial sintering increases the tensile strength of tape 184 as
compared to the relatively low tensile strength of unbound tape 36
within furnace 180.
[0220] Referring to FIG. 19, prophetic temperature profiles within
furnaces 180 and 182 are shown according to an exemplary
embodiment. As shown in FIG. 19, the heating elements of furnace
180 are controlled to generate temperature profile 190, and the
heating elements of furnace 182 are controlled to generate
temperature profile 192. As will be noted, both profiles 190 and
192 have the same, low stress generating, gradual temperature
increase similar to that of temperature profile 160 discussed
above. However, profile 192 is located above profile 190 (e.g., has
a higher average temperature than profile 190) which causes the
additional, higher levels of sintering (e.g., additional shrinkage,
additional decrease in porosity) that occurs as partially sintered
tape 184 traverses furnace 182.
[0221] Referring to FIG. 20, a high throughput sintering system 200
is shown according to an exemplary embodiment. In general, system
200 includes two parallel systems 10, each sintering a tape
material. System 200 may be operated to increase the output of a
single type of sintered tape material, similar to the arrangement
in FIG. 18. Alternatively, each system 10 of system 200 may output
a different sintered tape material. In various embodiments, system
200 may include 3, 4, 5, etc. systems 10 in parallel to further
increase output of sintered tape material.
Sintering Station Examples and Models
[0222] Referring to FIG. 21 through FIG. 28, various sintering
tests and sintering models are described demonstrating the
sintering relations discussed herein, such as the relation between
temperature profile and shrinkage rate, the relation between the
temperature profile and stress with the tape material, the
relationship between stress and tape deformation, and the
relationship between tape width and risk of sintering
deformation.
Physical Sintering Test Example 1
[0223] In one example, a horizontal furnace with an actively
controlled multiple zone binder burnout furnace was tested. In this
test, a tape cast "green" zirconia ceramic ribbon (ceramic loaded
with polymer binder), 42 mm wide and about 25 microns thick, was
fed through a horizontal apparatus with the multi-zone binder
burnout furnace (similar to furnace 38 and binder removal station
34 above) at 20 inches per minute. The binder burnout furnace was
set at 325 degrees C. at the inlet to 475 degrees C. at the outlet
with 0-25 increasing degree C. increments for the four central hot
zones. Air flow at 7.5 liter per minute at a temperature range from
about 0.degree. C. to about 250.degree. C. was also provided, and
the air flow was divided between both sides of the burn out
furnace. The sintering furnace was 36 inches long and had an 18
inch long hot zone. The tape was transported within the sintering
furnace by sliding it over an alumina "D" tube, with a tension 20
grams and with the furnace set at 1225.degree. C. A resulting 10-20
feet of sintered zirconia tape was made and spooled on a take-up
reel 3 inches in diameter. Sintering shrinkage across the width was
about 12%.
Sintering Model 1
[0224] Referring to FIG. 21 and FIG. 22, sintering shrinkage of
zirconia as a function of time and temperature is shown. FIG. 21
shows a graph of sintering shrinkage of a zirconia tape at various
temperatures and times at temperature. FIG. 22 shows a graph of
curves generated by a mathematical function of the sintering
shrinkage of a zirconia tape at various temperatures and times at
temperature.
[0225] To generate the data points shown in FIG. 21, a tape cast
"green" zirconia ceramic ribbon (ceramic loaded with polymer
binder) about 15 mm wide, 25 microns thick was "bisque" fired to
1200.degree. C. at 8 inches per minute in the apparatus described
in Physical Sintering Test Example 1, above. Bisque fired tapes
produced in this manner were plunge fired in a narrow hot zone
furnace for 30 seconds, 1 minute, 2 minutes, 3 minutes and 5
minutes at 1250.degree. C., 1300.degree. C., 1350.degree. C.,
1400.degree. C., 1450.degree. C., and 1500.degree. C. Sintering
shrinkage was measured, and these data points are shown in FIG.
21.
[0226] From the sintering data, mathematical curves describing the
sintering shrinkage as a function of temperature and time were
fitted and extrapolated to lower and intermediate temperatures than
those actually tested. This curve fitting and extrapolation is
shown in FIG. 22. Based on the testing and curve fitting shown in
FIG. 21 and FIG. 22, the relation between sintering shrinkage,
sintering time and temperature for zirconia was determined.
Applicant believes this information can be used to develop
sintering temperature profiles for zirconia to achieve a desired
shrinkage rate and to reduce stress below the deformation
thresholds as discussed above.
[0227] In one specific embodiment, this data was used to model the
64 inch sintering furnace and temperature profile shown in FIG. 16.
As shown in FIG. 16, the thermal gradient/profile 160 started at
1250.degree. C. and ended at 1450.degree. C. The modeled
temperature increased from 1250.degree. C. to 1300.degree. C. from
0 to 8 inches into the furnace, was increased from 1300.degree. C.
to 1312.5.degree. C. from 8 to 16 inches, increased from 1312.5 to
1325.degree. C. from 16 to 24 inches, was maintained at
1325.degree. C. from 24 to 32 inches, increased from 1325 to
1375.degree. C. from 32 to 40 inches, was increased at 1375.degree.
C. to 1400.degree. C. from 40 to 48 inches, increased from 1400 to
1450.degree. C. from 48 to 56 inches, was maintained at
1450.degree. C. from 56 to 64 inches, then cooled to below
1000.degree. C. after 64 inches.
[0228] Shrinkage was modeled as a function of tape transport speed.
As shown in FIG. 16, the model showed that a faster transport
speed, 20 inches per minute (ipm), gave more uniform sintering
shrinkage over the length of the hot zone. Thus, this modeling
demonstrates that uniform shrinkage over longer lengths is
desirable because the shorter the distance over which the sintering
strain/shrinkage occurs, the larger the stress in the tape and the
greater propensity of buckling, and out of plane plastic
deformation.
Sintering Model 2
[0229] Referring to FIGS. 23 and 16, sinter stress was modeled by
finite element analysis (FEA) and a closed form (CF) solution. As
demonstrated in FIG. 23 and FIG. 24, as the tape being sintered
gets wider, extreme sintering stress of greater than -1000 MPa are
calculated for 100 mm wide stationary tapes (single hot zone), for
100 mm wide tapes where there are only two hot zones and for tape
transported at 8 and 16 inches per minute. In contrast, when 9 hot
zones are used with 2 sintering passes (equivalent to 18 hot zones
in a single pass), edge stresses less than about -200 MPa were
modeled for 150 mm wide sheet. In the single and 4 hot zone tests,
each hot zone was modeled having a length of 450 mm (18 inches)
with the furnace being 900 mm (36 inches) and thus, in these two
modeling examples additional hot zones equates to a longer hot
zone. For example, the 1 zone, 2 pass hot zone generally equates to
a total 900 mm long (36 inches) hot zone. However, for a 9 zone, 2
pass hot zone is equivalent to a total 3660 mm (144 inch) (length)
hot zone. Thus, FIG. 23 and FIG. 24 demonstrate that wider and
wider tapes (e.g., greater than 50 mm, 100 mm, 150 mm, 200 mm, 250
mm, etc.) can be accommodated by controlling the number of hot
zones (e.g., the total length of the sintering hot zone), the
temperature profile the tape is exposed to, and the movement rate
of the tape through the hot zone, sintering stress can be
maintained at levels low enough to avoid generation of deformation,
buckling, or breakage.
Sintering Model 3
[0230] FIG. 25 and FIG. 26 show a model of a bisque zirconia tape
(i.e., a partially sintered tape) that is passed twice through a
single hot zone with steep temperature gradients. The hot zones
were set at 1250.degree. C. for the first pass and then
1400.degree. C. for the second pass. Tape transport speeds of 8 and
16 inches per minute were inputs. The tape was modeled to be 20
microns thick and 15 mm and 40 mm wide. FIG. 25 shows shrinkage
through the hot zones, and FIG. 26 shows that substantial
compressive stress, greater than 90 MPa (for 40 mm wide tape at 8
ipm) is generated in the tape and greater than 120 MPa (for 40 mm
wide tape at 16 ipm) due to the rapid sintering strain. This is
believed to lead to buckling and out of plane deformation for tape
having these widths and thicknesses.
Sintering Model 4
[0231] FIG. 27 and FIG. 28 show the results when the model uses a
multi-zone furnace with ten hot zones and two passes with the
second pass set at higher temperatures than the first pass. The
modeled stress drops by an order of magnitude for both tape
transport speed and tape widths as compared to the stress shown in
FIG. 26. This lower stress is believed to lead to much flatter
tape, e.g., less deformation. Further, this model demonstrates the
effect of a controlled sintering temperature profile or gradual
rise of temperature during sintering on stress and consequently
deformation.
Physical Sintering Test Example 2
[0232] In another test example, a tape cast "green" zirconia
ceramic ribbon (ceramic loaded with polymer binder) about 25
microns thick and 15 cm wide was made with a vertically-oriented
sintering apparatus at a sintering temperature of 1100.degree. C.
About 50 feet was made and spooled on a take-up reel 3 inches in
diameter. Bisque sintering shrinkage width was about 10%
[0233] This 1100.degree. C. "bisque" tape was then passed through a
horizontal sintering furnace, substantially the same as that shown
in FIG. 12 at speeds of about 3, 10, 20, 30, 60 and 75 inches per
minute with the furnace set at 1550.degree. C. A resulting length
of 40 feet of sintered tape was made and spooled on a take-up reel
of 3 inches in diameter. Tension on the tape during sintering was
in the range of 10 grams, even at 75 inches per minute with the
tape in the hot zone for less than about 15 seconds, a porosity of
less than 20% was achieved. Slower speeds gave denser material.
Thus this test demonstrates that longer sintering furnaces lead to
higher density/lower porosity in the sintered tape and also that
higher temperature lead to higher density/lower porosity in the
sintered tape.
Physical Sintering Test Example 3
[0234] In another test example, a tape cast "green" alumina ceramic
ribbon (ceramic loaded with polymer binder) about 50 microns thick
was fed through a system substantially the same as that shown in
FIG. 3, at 4-6 inches per minute. The binder burnout furnace was
set at 325.degree. C. inlet to 475.degree. C. outlet with 0-25
increasing degree increments for the four central hot zones. A
5-7.5 liter per minute air flow at 0-250.degree. C. was used. The
sintering furnace was 36 inches long with an 18 inch hot zone set
at 1300.degree. C. The green tape was passed through the 18 inch
sintering hot zone at 1300.degree. C., producing a partially
sintered, "bisque" tape. The width of the partially sintered tape
was 7% less than the width of the green tape.
[0235] The 1300.degree. C. "bisque" tape was then passed through
the sintering furnace a second time at 2 inches per minute with the
sintering furnace set at 1550.degree. C., producing about 20 feet
of fully sintered alumina tape. The tape was spooled on a take-up
reel 6 inches in diameter. Tension on the tape was about 100 grams
during sintering, and sintering shrinkage width for the second pass
was about 15%. After sintering, the tape was translucent, almost
transparent. When set on a written document you could read through
it. The grain size was below about 2 microns and the material had
less than about 1% porosity.
Test Example 4
[0236] In another test example, a tape cast "green" zirconia
ceramic ribbon (ceramic loaded with polymer binder) about 50
microns thick was fed through a system substantially the same as
that shown in FIG. 3 at 6 inches per minute. The binder burnout
furnace was set at 300-475 degrees .degree. C., with -7.5 liters
per minute of air flow at 200-250.degree. C. The sintering furnace
was 36 inches long with an 18 inch hot zone. Temperature gradients
were 25.degree. C. to 1225.degree. C. in less than 9 inches and
1000.degree. C. to 1225.degree. C. over 3-4 inches. Two D tubes
spaced apart by about 3/8 inch were used to restrict air
circulation and lessen the temperature gradients. Tension in the
tape was 20-60 grams, and the sintering furnace was set at
1225.degree. C. A resulting length of 50 feet of sintered zirconia
was made and spooled on a take-up reel of 3 inches in diameter.
Sintering shrinkage width was about 12%.
[0237] To physically model a furnace with a shallow temperature
gradient, the 1225.degree. C. sintered "bisque tape" was passed
through the single zone furnace three times at progressively higher
temperatures, which reduces the sintering shrinkage for each pass,
reducing the out of plane deformation. Specifically, the
1225.degree. C. "bisque" tape was then passed through the furnace a
second time at 6 inches per minute with the furnace set at
1325.degree. C. Via this process 45 feet of sintered zirconia tape
was made and spooled on a take-up reel 3 inches in diameter.
Tension on the tape during sintering was 100-250 grams, and
sintering shrinkage width for this pass was 5-6%.
[0238] The 1325.degree. C. tape was then passed through the furnace
a third time at 6 inches per minute with the furnace set at
1425.degree. C. About 40 feet of sintered zirconia tape was made
and spooled on a take-up reel 3 inches in diameter. Tension on the
tape during sintering was 100-250 grams, and sintering shrinkage
width for this pass was 5-6%. After the 1425.degree. C. pass the
tape was translucent, almost transparent. When set on a written
document you could read through it.
[0239] The 1425.degree. C. tape was then passed through the furnace
a fourth time at 3-6 inches per minute with the furnace set at
1550.degree. C. A few feet of 1550.degree. C. sintered tape was
made and spooled on a take-up reel 3 inches in diameter. Tension on
the tape during sintering was 100-300 grams and sintering shrinkage
(width) for this pass was 0-2%.
Sintered Article
[0240] Embodiments of the sintered articles formed using the
systems and processes described herein will now be described. The
sintered articles may be provided in the form of a sintered tape
(i.e., a continuous sintered article) or a discrete sintered
article(s). Unless otherwise indicated, the term "sintered article"
is intended to refer to both a continuous sintered article and a
discrete sintered article(s). In addition, "sintered" refers to
both partially sintered articles and fully sintered articles. In
one aspect, embodiments of the sintered article comprise dimensions
not previously achievable. In one or more embodiments, the sintered
article also exhibit uniformity of certain properties along these
dimensions. According to another aspect, embodiments of the
sintered article exhibits a flattenability that indicates the
sintered article can be flattened or subjected to flattening
without imparting significant stress in the sintered article and
thus can be used successfully in downstream processes. Another
aspect pertains to embodiments of a rolled sintered article, and
yet another aspect pertains to embodiments of a plurality of
discrete sintered articles. Still other aspects include new
compositions of materials, or compositions with new
microstructures, such as in terms of unique grain boundaries, for
example.
[0241] Referring to FIG. 29, a sintered article 1000 according to
one or more embodiments includes a first major surface 1010, a
second major surface 1020 opposing the first major surface, and a
body 1030 extending between the first and second surfaces. The body
1030 has a thickness (t) defined as a distance between the first
major surface and the second major surface, a width (W) defined as
a first dimension of one of the first or second surfaces orthogonal
to the thickness, and a length (L) defined as a second dimension of
one of the first or second surfaces orthogonal to both the
thickness and the width. In one or more embodiments, the sintered
article includes opposing minor surfaces 1040 that define the width
(W). In specific embodiments, sintered article 1000, as described
herein, is an example of sintered tape 40 produced using system 10,
albeit some tapes of the present technology may be longer than the
tape shown in FIG. 29.
[0242] In one or more embodiments, the sintered article is a
continuous sintered article having a width of about 5 mm or
greater, a thickness in a range from about 3 .mu.m to about 1 mm,
and a length in a range of about 300 cm or greater. In other
embodiments, the width is less than 5 mm, as described above.
[0243] In one or more embodiments, the sintered article has a width
in a range from about 5 mm to about 200 mm, from about 6 mm to
about 200 mm, from about 8 mm to about 200 mm, from about 10 mm to
about 200 mm, from about 12 mm to about 200 mm, from about 14 mm to
about 200 mm, from about 15 mm to about 200 mm, from about 17 mm to
about 200 mm, from about 18 mm to about 200 mm, from about 20 mm to
about 200 mm, from about 22 mm to about 200 mm, from about 24 mm to
about 200 mm, from about 25 mm to about 200 mm, from about 30 mm to
about 200 mm, from about 40 mm to about 200 mm, from about 50 mm to
about 200 mm, from about 60 mm to about 200 mm, from about 70 mm to
about 200 mm, from about 80 mm to about 200 mm, from about 90 mm to
about 200 mm, from about 100 mm to about 200 mm, from about 5 mm to
about 150 mm, from about 5 mm to about 125 mm, from about 5 mm to
about 100 mm, from about 5 mm to about 75 mm, from about 5 mm to
about 50 mm, from about 5 mm to about 40 mm, from about 5 mm to
about 30 mm, from about 5 mm to about 20 mm, or from about 5 mm to
about 10 mm.
[0244] In some embodiments, the sintered article has a width W of
at least 0.5 mm, such as at least 1 mm, such as at least 2 mm, such
as at least 5 mm, such as at least 8 mm, such as at least 10 mm,
such as at least 15 mm, such as at least 20 mm, such as at least 30
mm, such as at least 50 mm, such as at least 75 mm, such as at
least 10 cm, such as at least 15 cm, such as at least 20 cm, and/or
no more than 2 m, such as no more than 1 m, such as no more than 50
cm, such as no more than 30 cm. In other embodiments, the sintered
article has a different width W.
[0245] In one or more embodiments, the sintered article has a
thickness (t) in a range from about 3 .mu.m to about 1 mm, from
about 4 .mu.m to about 1 mm, from about 5 .mu.m to about 1 mm, from
about 6 .mu.m to about 1 mm, from about 7 .mu.m to about 1 mm, from
about 8 .mu.m to about 1 mm, from about 9 .mu.m to about 1 mm, from
about 10 .mu.m to about 1 mm, from about 11 .mu.m to about 1 mm,
from about 12 .mu.m to about 1 mm, from about 13 .mu.m to about 1
mm, from about 14 .mu.m to about 1 mm, from about 15 .mu.m to about
1 mm, from about 20 .mu.m to about 1 mm, from about 25 .mu.m to
about 1 mm, from about 30 .mu.m to about 1 mm, from about 35 .mu.m
to about 1 mm, from about 40 .mu.m to about 1 mm, from about 45
.mu.m to about 1 mm, from about 50 .mu.m to about 1 mm, from about
100 .mu.m to about 1 mm, from about 200 .mu.m to about 1 mm, from
about 300 .mu.m to about 1 mm, from about 400 .mu.m to about 1 mm,
from about 500 .mu.m to about 1 mm, from about 3 .mu.m to about 900
.mu.m, from about 3 .mu.m to about 800 .mu.m, from about 3 .mu.m to
about 700 .mu.m, from about 3 .mu.m to about 600 .mu.m, from about
3 .mu.m to about 500 .mu.m, from about 3 .mu.m to about 400 .mu.m,
from about 3 .mu.m to about 300 .mu.m, from about 3 .mu.m to about
200 .mu.m, from about 3 .mu.m to about 100 .mu.m, from about 3
.mu.m to about 90 .mu.m, from about 3 .mu.m to about 80 .mu.m, from
about 3 .mu.m to about 70 .mu.m, from about 3 .mu.m to about 60
.mu.m, from about 3 .mu.m to about 50 .mu.m, from about 3 .mu.m to
about 45 .mu.m, from about 3 .mu.m to about 40 .mu.m, from about 3
.mu.m to about 35 .mu.m, from about 3 .mu.m to about 30 .mu.m, or
from about 3 .mu.m to about 30 .mu.m.
[0246] In some embodiments, the sintered article has a thickness t
of at least 3 .mu.m, such as at least 5 .mu.m, such as at least 10
.mu.m, such as at least 15 .mu.m, such as at least 20 .mu.m, such
as at least 25 .mu.m, such as at least 0.5 mm, such as at least 1
mm, and/or no more than 5 mm, such as no more than 3 mm, such as no
more than 1 mm, such as no more than 500 .mu.m, such as no more
than 300 .mu.m, such as no more than 100 .mu.m. In other
embodiments, the sintered article has a different thickness t.
[0247] In one or more embodiments, the sintered article is
continuous and has a length L in a range from about 300 cm to about
500 m, from about 300 cm to about 400 m, from about 300 cm to about
200 m, from about 300 cm to about 100 m, from about 300 cm to about
50 m, from about 300 cm to about 25 m, from about 300 cm to about
20 m, from about 350 cm to about 500 m, from about 400 cm to about
500 m, from about 450 cm to about 500 m, from about 500 cm to about
500 m, from about 550 cm to about 500 m, from about 600 cm to about
500 m, from about 700 cm to about 500 m, from about 800 cm to about
500 m, from about 900 cm to about 500 m, from about 1 m to about
500 m, from about 5 m to about 500 m, from about 10 m to about 500
m, from about 20 m to about 500 m, from about 30 m to about 500 m,
from about 40 m to about 500 m, from about 50 m to about 500 m,
from about 75 m to about 500 m, from about 100 m to about 500 m,
from about 200 m to about 500 m, or from about 250 m to about 500
m.
[0248] In some embodiments, the sintered article has a continuous,
unbroken length L of at least 5 mm, such as at least 25 mm, such as
at least 1 cm, such as at least 15 cm, such as at least 50 cm, such
as at least 1 m, such as at least 5 m, such as at least 10 m,
and/or no more than 5 km, such as no more than 3 km, such as no
more than 1 km, such as no more than 500 m, such as no more than
300 m, such as no more than 100 m. In other embodiments, the
sintered article has a different length L. Such continuous long
lengths, particularly of materials and qualities disclosed herein,
may be surprising to those of skill in the art without technologies
disclosed herein, such as the controlled separation, tension
control, sintering zones, binder removal techniques, etc.
[0249] In one or more embodiments, the body of the sintered article
includes a sintered inorganic material. In one or more embodiments,
the inorganic material includes an interface having a major
interface dimension of less than about 1 mm. As used herein, the
term "interface" when used with respect to the inorganic material
is defined as including either a chemical inhomogeneity or a
crystal structure inhomogeneity or both a chemical inhomogeneity
and a crystal structure inhomogeneity.
[0250] Exemplary inorganic materials include ceramic materials,
glass ceramic materials and the like. In some embodiments, the
inorganic material may include any one or more of a piezoelectric
material, a thermoelectric material, a pyroelectric material, a
variable resistance material, or an optoelectric material. Specific
examples of inorganic materials include zirconia (e.g.,
yttria-stabilized zirconia), alumina, spinel, garnet, lithium
lanthanum zirconium oxide (LLZO), cordierite, mullite, perovskite,
pyrochlore, silicon carbide, silicon nitride, boron carbide, sodium
bismuth titanate, barium titanate, titanium diboride, silicon
alumina nitride, aluminum oxynitride, or a reactive cerammed
glass-ceramic (a glass ceramic formed by a combination of chemical
reaction and devitrification, which includes an in situ reaction
between a glass frit and a reactant powder(s)).
[0251] In one or more embodiments, the sintered article exhibits
compositional uniformity across a specific area. In one or more
specific embodiments, the sintered article comprises at least 10
square cm of area along the length that has a composition (i.e.,
relative amounts of chemicals in weight percent (%)) wherein at
least one constituent of the composition varies by less than about
3 weight % (e.g., about 2.5 weight % or less, about 2 weight % or
less, about 1.5 weight % or less, about 1 weight % or less, or
about 0.5 weight % or less), across that area. For example, when
the inorganic material comprises alumina, the amount of aluminum
may vary by less than about 3 weight % (e.g., about 2.5 weight % or
less, about 2 weight % or less, about 1.5 weight % or less, about 1
weight % or less, or about 0.5 weight % or less), across the at
least 10 square cm of area. Such compositional uniformity may be
attributed at least in part to new, unique processes, as disclosed
herein, such as the furnace heat zones with individually controlled
elements, careful and gentle handling of green tape, steady state
of the continuous tape processing, etc. In other embodiments, new
and inventive tapes or other products of at least some technology
disclosed herein may not have such compositional uniformity.
[0252] In one or more embodiments, the sintered article exhibits
crystalline structure uniformity across a specific area. In one or
more specific embodiments, the sintered article includes at least
10 square cm of area along the length that has a crystalline
structure with at least one phase having a weight % that varies by
less than about 5 percentage points, across that area. For
illustration only, the sintered article may include at least one
phase that constitutes 20 weight % of the sintered article and the
amount of this phase is within the range from about 15 weight % to
about 25 weight % across the at least 10 square cm of area. In one
or more embodiments, the sintered article includes at least 10
square cm of area along the length that has a crystalline structure
with at least one phase having a weight % that varies by less than
about 4.5 percentage points, less than about 4 percentage points,
less than about 3.5 percentage points, less than about 3 percentage
points, less than about 2.5 percentage points, less than about 2
percentage points, less than about 1.5 percentage points, less than
about 1 percentage point, or less than about 0.5 percentage points,
across that area. Such crystalline structure uniformity may be
attributed at least in part to new, unique processes, as disclosed
herein, such as the furnace heat zones with individually controlled
elements, careful and gentle handling of green tape, steady state
of the continuous tape processing, etc. In other embodiments, new
and inventive tapes or other products of at least some technology
disclosed herein may not have such crystalline structure
uniformity.
[0253] In one or more embodiments, the sintered article exhibits a
porosity uniformity across a specific area. In one or more specific
embodiments, the sintered article comprises at least 10 square cm
of area along the length that has a porosity varies by less than
about 20%. As used herein, the term "porosity" is described as a
percent by volume (e.g., at least 10% by volume, or at least 30% by
volume), where the "porosity" refers to the portions of the volume
of the sintered article unoccupied by the inorganic material.
Accordingly, in one example, the sintered article has a porosity of
10% by volume and this porosity is within a range from about
greater than 8% by volume to less than about 12% by volume across
the at least 10 square cm of area. In one or more specific
embodiments, the sintered article comprises at least 10 square cm
of area along the length that has a porosity varies by 18% or less,
16% or less, 15% or less, 14% or less, 12% or less, 10% or less, 8%
or less, 6% or less, 5% or less, 4% or less or about 2% or less,
across that area. Such porosity uniformity may be attributed at
least in part to new, unique processes, as disclosed herein, such
as the furnace heat zones with individually controlled elements,
careful and gentle handling of green tape, steady state of the
continuous tape processing, etc. In other embodiments, new and
inventive tapes or other products of at least some technology
disclosed herein may not have such porosity uniformity.
[0254] In one or more embodiments, the sintered article exhibits a
granular profile, such as when viewed under a microscope, as shown
in the digital image of FIG. 30A for an example of such a granular
profile structure, and conceptually shown in the side view of FIG.
30B, that includes grains 1034 protruding generally outward from
the body 1030 with a height H (e.g., average height) of at least 25
nanometers (nm) and/or no more than 150 micrometers (.mu.m)
relative to recessed portions of the surface at boundaries 1032
between the grains 1034. In one or more embodiments, the height H
in a range from about 25 nm to about 125 .mu.m, from about 25 nm to
about 100 .mu.m, from about 25 nm to about 75 .mu.m, from about 25
nm to about 50 .mu.m, from about 50 nm to about 150 .mu.m, from
about 75 nm to about 150 .mu.m, from about 100 nm to about 150
.mu.m, or from about 125 nm to about 150 .mu.m. In one or more
embodiments, the height H in a range from about 25 nm to about 125
nm, from about 25 nm to about 100 nm, from about 25 nm to about 75
nm, from about 25 nm to about 50 nm, from about 50 nm to about 150
nm, from about 75 nm to about 150 nm, from about 100 nm to about
150 nm, or from about 125 nm to about 150 nm. In other embodiments,
the height H may be otherwise sized. In still other embodiments,
processing conditions (e.g., time, temperature) may be such that
the sintered material has essentially zero height H. In some
embodiments, for materials and manufacturing disclosed herein,
products (e.g., tape) include a height H of grains of at least 25
nm, such as at least 50 nm, such as at least 75 nm, such as at
least 100 nm, such as at least 125 nm, such as at least 150 nm,
and/or no more than 200 .mu.m, such as no more than 150 .mu.m, such
as no more than 100 .mu.m, such as no more than 75 .mu.m, such as
no more than 50 .mu.m. Size and shape of such microstructure may be
controlled using technology disclosed herein, such as rate of
conveyance through the furnace, temperature(s) and temperature
profile of the furnace, composition, particle/grain size and
density of inorganic material in the green tape, and other factors
as disclosed herein.
[0255] The granular profile is or may be an indicator of the
process of manufacturing used to form the sintered article 1000. In
particular, the granular profile is or may be an indicator that the
article 1000 was sintered as a thin continuous article (i.e., as a
sheet or tape), as opposed to being cut from a boule, and that the
respective surface 1010, 1020 has not been substantially polished.
Additionally, compared to polished surfaces, the granular profile
may provide benefits to the sintered article 1000 in some
applications, such as scattering light for a backlight unit of a
display, increasing surface area for greater adhesion of a coating
or for culture growth. In contemplated embodiments, the surfaces
1010, 1020 have a roughness from about 10 nm to about 1000 nm
across a distance of 10 mm in one dimension along the length of the
sintered article, such as from about 15 nm to about 800 nm. In
contemplated embodiments, either or both of the surfaces 1010, 1020
have a roughness of from about 1 nm to about 10 .mu.m over a
distance of 1 cm along a single axis.
[0256] In one or more embodiments, the one or both surfaces 1010,
1020 may be polished, where grain boundary grooves and grain
asperities (or hillocks) are generally removed due to the
polishing. In contemplated embodiments, sintered articles 1000
manufactured according to the processes disclosed herein may be
polished, with a surface similar to that shown in FIGS. 31A-31B for
example; depending upon, for example, the particular intended use
of the article. For example, use of the sintered article 1000 as a
substrate may not require an extremely smooth surface, and the
unpolished surface of FIGS. 30A-30B may be sufficient; whereas use
of the article as a mirror or as a lens may require polishing as
shown in FIG. 31A-31B. However, as disclosed herein, polishing may
be difficult for particularly thin articles or those that are thin
with large surface areas. As indicated, substrates disclosed herein
may also receive coatings which may change surface qualities, such
as smoothness.
[0257] Without being bound by theory, it is believed that sheets of
sintered ceramic or other materials cut from boules may not have
readily identifiable grain boundaries present on surfaces thereon,
in contrast to the article of FIGS. 30A-30B. Without being by
theory, boule-cut articles may typically be polished to correct
rough surfaces from the cutting, such as with grooves from
abrasion; however surface polishing may be particularly difficult
or cumbersome for very thin articles of sintered ceramic or other
materials, with the degree of difficulty increasing as such
articles are thinner and the surface areas of such articles are
larger. However, sintered articles manufactured according to the
presently disclosed technology may be less constrained by such
limitations because articles manufactured according to the present
technology may be continuously manufactured in long lengths of
tape. Further, dimensions of furnace systems, as disclosed herein,
may be scaled to accommodate and sinter wider articles as described
herein.
[0258] In some embodiments, such as where the sintered article 1000
is in the form of a sheet or tape, the surface consistency is such
that either one or both of the first and second surfaces 1010, 1020
have few surface defects. In this context, surface defects are
abrasions and/or adhesions having a dimension along the respective
surface of at least 15 .mu.m, 10 .mu.m, and/or 5 .mu.m. In one or
more embodiments, one or both the first major surface 1010 and
second major surface 1020 have fewer than 15, 10, and/or 5 surface
defects having a dimension greater than 15 .mu.m, 10 .mu.m, and/or
5 .mu.m per square centimeter. In one example, one or both the
first major surface 1010 and second major surface 1020 have fewer
than 3 or fewer than 1 such surface defects on average per square
centimeter. In one or more embodiments, one of or both the first
major surface and the second major surface have at least ten square
centimeters of area having fewer than one hundred surface defects
from adhesion or abrasion with a dimension greater than 5 .mu.m.
Alternatively or additionally, one of the first and major surface
has at least ten square centimeters of area having fewer than one
hundred surface defects from adhesion or abrasion with a dimension
greater than 5 .mu.m, while the other of the first major surface
and the second major surface comprises surface defects from
adhesion or abrasions with a dimension of greater than 5 .mu.m.
Accordingly, sintered articles manufactured according to inventive
technologies disclosed herein may have relatively high and
consistent surface quality. Applicant believes that the high and
consistent surface quality of the sintered article 1000 facilitates
increased strength of the article 1000 by reducing sites for stress
concentrations and/or crack initiations.
[0259] The sintered article may be described as having a flatness
in a range from about 0.1 .mu.m (100 nm) to about 50 .mu.m over a
distance of 1 cm along a single axis (e.g., such as along the
length or the width of the sintered article). In some embodiments,
the flatness may be in a range from about 0.2 .mu.m to about 50
.mu.m, from about 0.4 .mu.m to about 50 .mu.m, from about 0.5 .mu.m
to about 50 .mu.m, from about 0.6 .mu.m to about 50 .mu.m, from
about 0.8 .mu.m to about 50 .mu.m, from about 1 .mu.m to about 50
.mu.m, from about 2 .mu.m to about 50 .mu.m, from about 5 .mu.m to
about 50 .mu.m, from about 10 .mu.m to about 50 .mu.m, from about
20 .mu.m to about 50 .mu.m, from about 25 .mu.m to about 50 .mu.m,
from about 30 .mu.m to about 50 .mu.m, from about 0.1 .mu.m to
about 45 .mu.m, from about 0.1 .mu.m to about 40 .mu.m, from about
0.1 .mu.m to about 35 .mu.m, from about 0.1 .mu.m to about 30
.mu.m, from about 0.1 .mu.m to about 25 .mu.m, from about 0.1 .mu.m
to about 20 .mu.m, from about 0.1 .mu.m to about 15 .mu.m, from
about 0.1 .mu.m to about 10 .mu.m, from about 0.1 .mu.m to about 5
.mu.m, or from about 0.1 .mu.m to about 1 .mu.m. Such flatness, in
combination with the surface quality, surface consistency, large
area, thin thickness, and/or material properties of materials
disclosed herein, may allow sheets, substrates, sintered tapes,
articles, etc. to be particularly useful for various applications,
such as tough cover sheets for displays, high-temperature
substrates, flexible separators, and other applications. With that
said, embodiments may not have such flatness. Flatness is measured
with a respective national standard (e.g. ASTM A1030).
[0260] In one or more embodiments, the sintered article exhibits a
striated profile along the width dimension as shown in FIG. 32. In
one or more embodiments, the body 1030 has a striated profile with
a thickness that is substantially constant along the width. For
example, the thickness along the entire width is in a range from
about 0.9 t to about 1.1 t (e.g., from about 0.95 t to about 1.1 t,
from about 0.1 t to about 1.1 t, from about 0.105 t to about 1.1 t,
from about 0.9 t to about 1.05 t, from about 0.9 t to about t, or
from about 0.9 t to about 0.95 t), where t is the thickness values
disclosed herein. As shown in FIG. 32, the striated profile
includes two or more undulations along the width. As used herein,
undulations mean a full period. In some embodiments, the striated
profile includes 3 or more undulations, 4 or more undulations, 5 or
more undulations or 10 or more undulations along the entire width,
with the upper limit of undulations being about less than about 20
undulations along the entire width. In one or more embodiments, the
striations may be measured in terms of optical distortion. In one
or more embodiments, the sintered article may be placed in
proximity to a zebra board that consists of a white board with
straight black stripes disposed diagonally across the board. When
viewing the zebra board through the sintered article, distortions
in the black stripes may be visually detected and measured using
methods and tools known in the art. In one example, the distortions
may be measured according to ASTM C 1048. In other embodiments,
such as with polished or otherwise formed articles disclosed
herein, there may be fewer or no distortions. In still other
embodiments, distortions may be greater in quantity and/or
magnitude.
[0261] In one or more embodiments, the sintered article may be
planar. In one or more embodiments, a portion of the sintered
article or a discrete sintered article (as will be described
herein) may have a have a three-dimensional shape. For example, in
one or more embodiments, a portion of the sintered article or a
discrete sintered article may have a saddle shape (which has a
convex shape along the width and a concave shape along the length,
or a concave shape along the width and a convex shape along the
length). In one or more embodiments, a portion of the sintered
article or a discrete sintered article may have a c-shape (which
has a single concave shape along the length). In one or more
embodiments, the shape magnitude (which means the maximum height of
the portion of the sintered article or a discrete sintered article
measured from the plane on which it is disposed) is less than about
0.75 mm (e.g., about 0.7 mm or less, 0.65 mm or less, 0.6 mm or
less, 0.55 mm or less, 0.5 mm or less, 0.45 mm or less, 0.4 mm or
less, 0.35 mm or less, 0.3 mm or less, 0.25 mm or less, 0.2 mm or
less, 0.15 mm or less, or 0.1 mm or less).
[0262] According to another aspect, the embodiments of the sintered
article may be described in terms of flattenability or being
flattenable in standard, room temperature (at 23.degree. C.)
conditions, without heating the sintered article near melting or
sintering temperature to soften the article for flattening. In some
embodiments, a portion of the sintered article is flattenable. A
portion of the sintered article that is flattenable may have a
length of about 10 cm or less. In some embodiments, the sintered
article may have dimensions otherwise described herein (e.g., width
is about 5 mm or greater, the thickness is in a range from about 3
.mu.m to about 1 mm, and the length is about 300 cm or greater),
with the portion of the sintered article that is flattenable having
a length of 10 cm or less. In some embodiments, for instance where
the sintered article is a discrete sintered article, the entire
sintered article is flattenable.
[0263] As used herein, flattenability is determined by flattening
the sintered article by pinching the sintered article (or portion
of the sintered article) between two rigid parallel surfaces, or by
applying surface pressure on a first major surface 1010 of the
sintered article (or portion of the sintered article) against a
rigid surface to flatten the sintered article (or portion of the
sintered article) along a planar flattening plane. The measure of
flattenability may be expressed as the force required to pinch the
sintered article (or portion of the sintered article) flat to
within a distance of 0.05 mm, 0.01 mm or 0.001 mm from the
flattening plane, when the sintered article (or portion of the
sintered article) is pinched between two rigid parallel surfaces.
The measure of flattenability may alternatively be expressed as the
surface pressure applied to a first major surface 1010 to push the
sintered article (or portion of the sintered article) flat to
within a distance of 0.001 mm from the flattening plane, when the
sintered article (or portion of the sintered article) is pushed
against a rigid surface. The measure of flattenability may be
expressed as the absolute maximum in plane surface stress
(compressive or tensile) on the sintered article (or portion of the
sintered article) when the sintered article (or portion of the
sintered article) is flattened to within a distance of 0.05 mm,
0.01 mm or 0.001 mm from the flattening plane using either
flattening method (i.e., pinching between two rigid parallel
surfaces or against a rigid surface). This stress may be determined
using the thin plate bend bending equation,
.sigma..sub.x=Et/2R(1-.nu..sup.2).
[0264] The thin plate bend stress equation is derived from the
equation
.sigma..sub.x=[E/(1-.nu..sup.2)](.epsilon..sub.x+.nu..epsilon..sub.y),
where E is elastic modulus, .nu. is Poisson's ratio and
.epsilon..sub.x and .epsilon..sub.y are strain in the respective
directions. With a thick beam, where deflection is much less than
the beam thickness, .epsilon..sub.x is proportional to thickness
squared. However, when the beam thickness is significantly less
than the bend radius (e.g., the sintered article may have a
thickness t of about 20 .mu.m and is bent to a bend radius of a
millimeter magnitude), .epsilon..sub.y=0 is applicable. As
illustrated in FIG. 33, it is assumed that the thin plate (or
sintered article) is bent into a section of a circle where the
length of the neutral axis, L.sub.0 is .crclbar..times.R, where
.crclbar. is in radians and R is the bend radius, the length of the
outer fiber, L.sub.1 is .crclbar..times.(R+t/2), where .crclbar. is
in radians and R is the bend radius and t is the thickness,
.epsilon..sub.x on the outer fiber is (L.sub.1-L.sub.0)/L.sub.0,
and thus,
.epsilon..sub.x=[.crclbar..times.(R+t/2)-(.crclbar..times.R)].times.1/(.c-
rclbar..times.R)=t/2R. The equation
.sigma..sub.x=[E/(1-.nu..sup.2)]t/2R becomes the thin plate bending
equation above (.sigma..sub.x=Et/2R(1-.nu..sup.2)).
[0265] In one or more embodiments, the sintered article or the
portion of the sintered article, when flattened at least to
magnitudes described above, exhibits a maximum in plane stress
(which is defined as the maximum absolute value of stress
regardless of whether it is compressive stress or tensile stress,
as determined by the thin plate bend bending equation) of less than
or equal to 25% of the bend strength (which is measured by 2-point
bend strength) of the sintered article. For example, the maximum in
plane stress of the sintered article or the portion of the sintered
article may be less than or equal to 24%, less than or equal to
22%, less than or equal to 20%, less than or equal to 18%, less
than or equal to 16%, less than or equal to 15%, less than or equal
to 14%, less than or equal to 12%, less than or equal to 10%, less
than or equal to 5%, or less than or equal to 4%, of the bend
strength of the sintered article.
[0266] In one or more embodiments, the sintered article or a
portion of the sintered article is flattenable such that the
sintered article or portion of the sintered article exhibits a
maximum in plane stress of less than or equal to 1% of the Young's
modulus of the sintered article, when flattened as described
herein. In one or more embodiments, the maximum in plane stress of
the sintered article may be less than or equal to 0.9%, 0.8%, 0.7%,
0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1% or 0.05% of the Young's modulus
of the sintered article.
[0267] In one or more embodiments, the sintered article or a
portion of the sintered article is flattenable such that when the
sintered article or the portion of the sintered article has a
thickness in a range from about 40 .mu.m to about 80 .mu.m (or
other thicknesses disclosed herein) and is bent to a bend radius of
greater than 0.03 m, the sintered article or portion hereof
exhibits a maximum in plane stress of less than or equal to 25% of
the bend strength of the article. In one or more embodiments, the
sintered article or a portion of the sintered article is
flattenable such that when the sintered article or the portion of
the sintered article has a thickness in a range from about 20 .mu.m
to about 40 .mu.m (or other thicknesses disclosed herein) and is
bent to a bend radius of greater than 0.015 m, the sintered article
or a portion of the sintered article exhibits a maximum in plane
stress of less than or equal to 25% of the bend strength (as
measured by 2-point bend strength) of the article. In one or more
embodiments, when the sintered article has a thickness in a range
from about 3 .mu.m to about 20 .mu.m (or other thicknesses
disclosed herein) and is bent to a bend radius of greater than
0.0075 m, the sintered article or a portion of the sintered article
exhibits a maximum in plane stress of less than or equal to 25% of
the bend strength (as measured by 2-point bend strength) of the
article.
[0268] In one or more embodiments, the sintered article or a
portion of the sintered article is flattenable such that when the
sintered article or the portion of the sintered article has a
thickness of about 80 .mu.m (or other thicknesses disclosed herein)
and is bent to a bend radius of greater than 0.03 m, the sintered
article or portion hereof exhibits a maximum in plane stress of
less than or equal to 25% of the bend strength of the article. In
one or more embodiments, the sintered article or a portion of the
sintered article is flattenable such that when the sintered article
or the portion of the sintered article has a thickness of about 40
.mu.m (or other thicknesses disclosed herein) and is bent to a bend
radius of greater than 0.015 m, the sintered article or a portion
of the sintered article exhibits a maximum in plane stress of less
than or equal to 25% of the bend strength (as measured by 2-point
bend strength) of the article. In one or more embodiments, when the
sintered article has a thickness of about 20 .mu.m (or other
thicknesses disclosed herein) and is bent to a bend radius of
greater than 0.0075 m, the sintered article or a portion of the
sintered article exhibits a maximum in plane stress of less than or
equal to 25% of the bend strength (as measured by 2-point bend
strength) of the article.
[0269] In one or more embodiments, the sintered article or a
portion thereof is flattenable such that the sintered article or a
portion thereof exhibits a maximum in plane stress of less than 250
MPa when flattened to within a distance of 0.05 mm, 0.010 mm or
0.001 mm from the flattening plane using either flattening method
(i.e., pinching between two rigid parallel surfaces or against a
rigid surface). In one or more embodiments, the maximum in plane
stress may be about 225 MPa or less, 200 MPa or less, 175 MPa or
less, 150 MPa or less, 125 MPa or less, 100 MPa or less, 75 MPa or
less, 50 MPa or less, 25 MPa or less, 15 MPa, 14 MPa or less, 13
MPa or less, 12 MPa or less, 11 MPa or less, 10 MPa or less, 9 MPa
or less, 8 MPa or less, 7 MPa or less, 6 MPa or less, 5 MPa or
less, or 4 MPa or less.
[0270] In one or embodiments, the sintered article or a portion
thereof is flattenable such that a force of less than 8 N (or 7 N
or less, 6 N or less, 5 N or less, 4 N or less, 3 N or less, 2 N or
less, 1 N or less, 0.5 N or less, 0.25 N or less, 0.1 N or less, or
0.05 N or less) is required to flatten the sintered article or a
portion thereof within a distance of 0.05 mm, 0.010 mm or 0.001 mm
from the flattening by pinching between two rigid parallel
surfaces.
[0271] In one or more embodiments, the sintered article or a
portion thereof is flattenable such that a pressure of 0.1 MPa or
less is required to push the sintered article (or portion of the
sintered article) flat to within a distance of 0.05 mm, 0.010 mm or
0.001 mm from the flattening plane, when the sintered article (or
portion of the sintered article) is pushed against a rigid surface.
In some embodiments, the pressure may be about 0.08 MPa or less,
about 0.06 MPa or less, about 0.05 MPa or less, about 0.04 MPa or
less, about 0.02 MPa or less, about 0.01 MPa or less, about 0.008
MPa or less, about 0.006 MPa or less, about 0.005 MPa or less,
about 0.004 MPa or less, about 0.002 MPa or less, about 0.001 MPa
or less, or 0.0005 MPa or less.
[0272] According to another aspect, the sintered article may be a
sintered tape material that is rolled into a rolled sintered
article as shown in FIG. 34A. In such embodiments, the rolled
sintered article includes a core 1100 and a sintered article 1200
(according to one or more embodiments described herein) wound
around the core. In one or more embodiments, the core is
cylindrical and has a diameter 1240 of less than 60 cm (or about 20
inches). For example, the core may have a diameter of about 55 cm
or less, 50 cm or less, about 48 cm or less, about 46 cm or less,
about 45 cm or less, about 44 cm or less, about 42 cm or less,
about 40 cm or less, about 38 cm or less, about 36 cm or less,
about 35 cm or less, about 34 cm or less, about 32 cm or less,
about 30 cm or less, about 28 cm or less, about 26 cm or less,
about 25 cm or less, about 24 cm or less, about 22 cm or less,
about 20 cm or less, about 18 cm or less, about 16 cm or less,
about 15 cm or less, about 14 cm or less, about 12 cm or less,
about 10 cm or less, about 8 cm or less, about 6 cm or less, about
5 cm or less, about 4 cm or less, or about 2 cm or less. In other
embodiments the core is otherwise shape and the roll bends around
the core in arcs corresponding to the above diameter
dimensions.
[0273] In one or more embodiments, the sintered article wound
around the core is continuous and has the dimensions otherwise
described herein (e.g., a width that is about 5 mm or greater, a
thickness in a range from about 3 .mu.m to about 1 mm, and a length
is about 30 cm or greater).
[0274] Spooling of a continuous sintered article (and in
particular, a continuous sintered inorganic material such as
ceramics) onto a core presents several challenges because the
sintered article has cross web shape, and web tensions that the
sintered article can tolerate, particularly in the binder burn out
and bisque states, are extremely low (e.g., tensions of gram level
magnitude). Furthermore, the modulus of the sintered material can
be very high (e.g., up to and including about 210 GPa) and
therefore, the sintered article does not stretch under tension and,
when wound around a core, the resulting wound roll integrity may be
poor. During handling the successive convolutions, a continuous
sintered article can easily telescope (i.e., the successive wraps
can move out of alignment).
[0275] Applicants have found that rolled sintered article of one or
more embodiments has superior integrity by using a compliant
interlayer support material when spooling the continuous sintered
article onto a core. In one or more embodiments, the continuous
sintered article is disposed on an interlayer support material and
the continuous sintered article and interlayer support material are
wound around the core such that each successive wrap of the
continuous sintered article is separated from one another by the
interlayer support material. As described above with reference to
FIG. 3, the sintered article (or sintered tape material) 40 is
wound upon uptake reel 44. The interlayer support material 46 is or
may be paid off of a reel 48 and the interlayer support material 46
is or may be wound onto uptake reel 44 such that a layer of
interlayer support material 46 is located between each layer, most,
or at least some layers of continuous sintered article 1000 (e.g.,
sintered article 1200 or sintered tape material 40) on uptake reel
44. This arrangement forms the rolled sintered material 50.
[0276] Referring to FIG. 34B, a detailed cross-sectional view of
the rolled sintered article 1200 of FIG. 34A is shown according to
an exemplary embodiment, where the sintered article 1200 has been
twice rolled around the core 1100 and interlayer support material
46 is positioned between the sintered article 1200 and the core
1100, and then between successive winds of the sintered article
1200. As may be intuitive from FIG. 34B, when viewed from an end,
the sintered article 1200 (in this case a tape) and the interlayer
support material 46 form intertwined spirals about the core 1100.
In other contemplated embodiments, the sintered article may be cut
into discrete sheets and still wound on a core and separated from
adjoining winds by a continuous interlayer support material 46,
such as where the net length of the sheets when added together is a
length L as described herein. As shown in FIG. 34B, in various
embodiments, the rolled sintered article includes interlayer
support material 46 between each layer of rolled sintered article
(e.g., sintered article 1000, sintered article 1200 or sintered
tape material 40) is shown according to an exemplary embodiment. In
various embodiments, the interlayer support material includes a
first major surface and a second major surface opposing the first
major surface, an interlayer thickness (t) defined as a distance
between the first major surface and the second major surface, an
interlayer width defined as a first dimension of one of the first
or second surfaces orthogonal to the interlayer thickness, and an
interlayer length defined as a second dimension of one of the first
or second major surfaces orthogonal to both the interlayer
thickness and the interlayer width of the interlayer support
material. In one or more exemplary embodiments, the interlayer
thickness is greater than the thickness of the sintered article. In
one or more embodiments the interlayer width may be greater than
the width of the rolled sintered article.
[0277] In one or more embodiments, the interlayer support material
46 comprises a tension (or is under a tension) that is greater than
a tension on the continuous sintered article, as measured by a load
cell. In one or more embodiments, the interlayer support material
has a relatively low modulus (compared to the sintered article) and
thus is stretched under low tension. It is believed that this
creates higher interlayer roll pressures that improve the wound
roll integrity. Furthermore, the tension in the wound roll in some
embodiments is controlled by controlling the tension applied to the
interlayer support material and that tension can be tapered as a
function of wound roll diameter. In some such embodiments, the
interlayer support material 46 is in tension, while the sintered
article (e.g., tape) is in compression.
[0278] In one or more embodiments, the interlayer support material
is thickness compliant (i.e., the thickness can be decreased by
applying pressure to a major surface and can therefore compensate
for variation in the cross web shape or thickness in the sintered
article generated by the sintering process). In some such
embodiments, when viewed from the side, the sintered article may be
hidden within the roll by the interlayer support material, where
the interlayer support material contacts adjoining winds of
interlayer support material and, at least to some degree, shields
and isolates the sintered article, such as where the interlayer
support material is wider than the sintered article as shown in
FIG. 34B and extends beyond both width-wise edges of the sintered
article (e.g. tape).
[0279] Referring to FIG. 34A, in one or more embodiments, the
rolled article is on a cylindrical core and has a diameter 1220 and
a side wall width 1230 that are substantially constant. The
interlayer support material enables spooling of the continuous or
non-continuous sintered article around the core, without causing
telescoping, which can increase the side wall width of the rolled
article. In some embodiments, the core comprises a circumference
and a core centerline along the circumference, the continuous
sintered article comprises an article centerline along a direction
of the length, and the distance between the core centerline and the
article centerline is 2.5 mm or less, along at least 90% or the
entire length of the continuous or non-continuous sintered
article.
[0280] In one or more embodiments, the rolled article comprises a
frictional force between the interlayer support material and the
continuous or non-continuous sintered article that is sufficient to
resist lateral telescoping of the successive convolutions in the
wound roll, even when very low tension is applied to the interlayer
support material. A constant tension may be applied to the
interlayer support material; however, the tension applied to the
interior portions of the rolled article toward the core may be
greater than the tension applied to exterior portions of the rolled
article away from the core due to the diameter of the rolled
article increasing from the core to the exterior portions as more
interlayer support material and continuous sintered article is
wound around the core. This compresses or may compress the rolled
article, which, when coupled with the friction between the
interlayer support material and the continuous sintered article,
prevents or limits telescoping and relative movement between
sintered article surfaces to at least help prevent defects.
[0281] In one or more embodiments, the interlayer support material
comprises any one of or both a polymer and a paper. In some
embodiments, the interlayer support material is a combination of
polymer and paper. In one or more embodiments, the interlayer
support material may include a foamed polymer. In some embodiments,
the foamed polymer is closed cell.
[0282] According to another aspect, the sintered articles described
herein may be provided as a plurality of discrete sintered
articles, as disclosed above, as illustrated in FIG. 35 and FIG.
36. In one or more embodiments, the discrete sintered articles may
be formed from a rolled sintered article or a continuous sintered
article, as described herein. For example, the discrete sintered
articles may be laser cut or otherwise separated from a larger
sintered article (which may be in sheet or tape form). In one or
more embodiments, each of the plurality of discrete sintered
articles has a uniformity or consistency with respect to some or
all others of the plurality of discrete sintered articles, as may
be due to the improved processes and material properties described
herein. In one or more embodiments, each of the plurality of
sintered articles include a first major surface, a second major
surface opposing the first major surface, and a body extending
between the first and second surfaces. The body includes a sintered
inorganic material and a thickness (t) defined as a distance
between the first major surface and the second major surface, a
width defined as a first dimension of one of the first or second
surfaces orthogonal to the thickness, and a length defined as a
second dimension of one of the first or second surfaces orthogonal
to both the thickness and the width. As may be intuitive, the
discrete sheets or other sintered articles cut or formed from a
longer tape have uniform and consistent compositions as disclosed
above, uniform and consistent crystal structure, uniform and
consistent thickness, levels of defects, and other properties
described herein that are or may be present in a tape or other
elongate article manufactured with the inventive equipment and
processes disclosed herein.
[0283] In one or more embodiments, some, most, or each of the
plurality of sintered articles is flattenable, as described herein.
In one or more embodiments, some, most, or each of the plurality of
sintered articles, when flattened, exhibits a maximum in plane
stress (which is defined as the maximum absolute value of stress
regardless of whether it is compressive stress or tensile stress,
as determined by the thin plate bend bending equation) of less than
or equal to 25% of the bend strength (which is measured by 2-point
bend methods) of the sintered article. For example, the maximum in
plane stress of some, most, or each of the plurality of sintered
articles may be less than or equal to 24%, less than or equal to
22%, less than or equal to 20%, less than or equal to 18%, less
than or equal to 16%, less than or equal to 15%, less than or equal
to 14%, less than or equal to 12%, less than or equal to 10%, less
than or equal to 5%, or less than or equal to 4%, of the bend
strength of the sintered article.
[0284] In one or more embodiments, some, most, or each of the
plurality of sintered articles is flattenable such that some, most,
or each of the plurality of sintered articles exhibits a maximum in
plane stress of less than or equal to 1% of the Young's modulus of
the sintered article, when flattened as described herein. In one or
more embodiments, the maximum in plane stress of some, most, or
each of the plurality of sintered articles may be less than or
equal to 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1% or
0.05% of the Young's modulus of the respective sintered
article.
[0285] In one or more embodiments, some, most, or each of the
plurality of sintered articles is flattenable such that when the
sintered article has a thickness in a range from about 40 .mu.m
about 80 .mu.m (or other thickness disclosed herein) and is bent to
a bend radius of greater than 0.03 m, the sintered article exhibits
a maximum in plane stress of less than or equal to 25% of the bend
strength of the article. In one or more embodiments, some, most, or
each of the plurality of sintered articles is flattenable such that
when the sintered article has a thickness in a range from about 20
.mu.m to about 40 .mu.m (or other thickness disclosed herein) and
is bent to a bend radius of greater than 0.015 m, the sintered
article exhibits a maximum in plane stress of less than or equal to
25% of the bend strength (as measured by 2-point bend strength) of
the article. In one or more embodiments, some, most, or each of the
plurality of sintered articles is flattenable such that when the
sintered article has a thickness in a range from about 3 .mu.m to
about 20 .mu.m (or other thickness disclosed herein) and is bent to
a bend radius of greater than 0.0075 m, the sintered article
exhibits a maximum in plane stress of less than or equal to 25% of
the bend strength (as measured by 2-point bend strength) of the
article.
[0286] In one or more embodiments, some, most, or each of the
plurality of sintered articles is flattenable such that when the
sintered article has a thickness of about 80 .mu.m (or other
thickness disclosed herein) and is bent to a bend radius of greater
than 0.03 m, the sintered article exhibits a maximum in plane
stress of less than or equal to 25% of the bend strength of the
article. In one or more embodiments, some, most, or each of the
plurality of sintered articles is flattenable such that when the
sintered article has a thickness of about 40 .mu.m (or other
thickness disclosed herein) and is bent to a bend radius of greater
than 0.015 m, the sintered article exhibits a maximum in plane
stress of less than or equal to 25% of the bend strength (as
measured by 2-point bend strength) of the article. In one or more
embodiments, some, most, or each of the plurality of sintered
articles is flattenable such that when the sintered article has a
thickness of about 20 .mu.m (or other thickness disclosed herein)
and is bent to a bend radius of greater than 0.0075 m, the sintered
article exhibits a maximum in plane stress of less than or equal to
25% of the bend strength (as measured by 2-point bend strength) of
the article.
[0287] In one or more embodiments, some, most, or each of the
plurality of sintered articles is flattenable such that the
sintered article exhibits a maximum in plane stress of less than
250 MPa when flattened to within a distance of 0.05 mm, 0.01 mm, or
0.001 mm from the flattening plane using either flattening method
(i.e., pinching between two rigid parallel surfaces or against a
rigid surface). In one or more embodiments, the maximum in plane
stress may be about 225 MPa or less, 200 MPa or less, 175 MPa or
less, 150 MPa or less, 125 MPa or less, 100 MPa or less, 75 MPa or
less, 50 MPa or less, 25 MPa or less, 15 MPa, 14 MPa or less, 13
MPa or less, 12 MPa or less, 11 MPa or less, 10 MPa or less, 9 MPa
or less, 8 MPa or less, 7 MPa or less, 6 MPa or less, 5 MPa or
less, or 4 MPa or less.
[0288] In one or embodiments, some, most, or each of the plurality
of sintered articles is flattenable such that a force of less than
8 N (or 7 N or less, 6 N or less, 5 N or less, 4 N or less, 3 N or
less, 2 N or less, 1 N or less, 0.5 N or less, 0.25 N or less, 0.1
N or less, or 0.05 N or less) is required to flatten the sintered
article or a portion thereof, respectively, when the sintered
article is flattened to within a distance of 0.05 mm, 0.01 mm, or
0.001 mm from the flattening by pinching between two rigid parallel
surfaces.
[0289] In one or embodiments, some, most, or each of the plurality
of sintered articles is flattenable such that a pressure of 0.1 MPa
or less is required to push the sintered article flat to within a
distance of 0.05 mm, 0.01 mm, or 0.001 mm from the flattening
plane, when pushed against a rigid surface. In some embodiments,
the pressure may be about 0.08 MPa or less, about 0.06 MPa or less,
about 0.05 MPa or less, about 0.04 MPa or less, about 0.02 MPa or
less, about 0.01 MPa or less, about 0.008 MPa or less, about 0.006
MPa or less, about 0.005 MPa or less, about 0.004 MPa or less,
about 0.002 MPa or less, about 0.001 MPa or less, or 0.0005 MPa or
less.
[0290] In one or more embodiments, the thickness of some, most, or
each of the plurality of sintered articles is within a range from
about 0.7 t to about 1.3 t (e.g., from about 0.8 t to about 1.3 t,
from about 0.9 t to about 1.3 t, from about t to about 1.3 t, from
about 1.1 t to about 1.3 t, from about 0.7 t to about 1.2 t, from
about 0.7 t to about 1.1 t, from about 0.7 t to about it, or from
about 0.9 t to about 1. It), where t is the thickness values
disclosed herein.
[0291] In one or more embodiments, some, most, or each of the
plurality of sintered article exhibits compositional uniformity. In
one or more embodiments, at least 50% (e.g., about 55% or more,
about 60% or more, or about 75% or more) of the plurality of
sintered articles comprise an area and a composition, wherein at
least one constituent of the composition (as described herein)
varies by less than about 3 weight % across the area. In some
embodiments, at least one constituent of the composition varies by
about 2.5 weight % or less, about 2 weight % or less, about 1.5
weight % or less, about 1 weight % or less, or about 0.5 weight %
or less), across that area. In one or more embodiments, the area is
about 1 square centimeter of the sintered article, or the area is
the entire surface area of the sintered articles.
[0292] In one or more embodiments, some, most, or each of the
plurality of sintered article exhibits crystalline structure
uniformity. In one or more embodiments, at least 50% (e.g., about
55% or more, about 60% or more, or about 75% or more) of the
plurality of sintered articles comprise an area and a crystalline
structure with at least one phase having a weight percent that
varies by less than about 5 percentage points (as described herein)
across the area. For illustration only, some, most, or each of the
plurality of sintered article may include at least one phase that
constitutes 20 weight % of the sintered article and, in at least
50% (e.g., about 55% or more, about 60% or more, or about 75% or
more) of the plurality of sintered articles, this phase is present
in an amount in a range from about 15 weight % to about 25 weight %
across the area. In one or more embodiments, at least 50% (e.g.,
about 55% or more, about 60% or more, or about 75% or more) of
some, most, or each of the plurality of sintered articles comprise
an area and a crystalline structure with at least one phase having
a weight percent that varies by less than about 4.5 percentage
points, less than about 4 percentage points, less than about 3.5
percentage points, less than about 3 percentage points, less than
about 2.5 percentage points, less than about 2 percentage points,
less than about 1.5 percentage points, less than about 1 percentage
point, or less than about 0.5 percentage points, across that area.
In one or more embodiments, the area is about 1 square centimeter
of the sintered article, or the area is the entire surface area of
the sintered articles.
[0293] In one or more embodiments, at least 50% (e.g., about 55% or
more, about 60% or more, or about 75% or more) of the plurality of
sintered article comprise an area and a porosity (as described
herein) that varies by less than about 20%. Accordingly, in one
example, some, most, or each of the plurality of sintered articles
has a porosity of 10% by volume and this porosity is within a range
from about greater than 8% by volume to less than about 12% by
volume across the area in at least 50% of the plurality of sintered
articles. In one or more specific embodiments, at least 50% of the
plurality of sintered articles comprises an area and has a porosity
that varies by 18% or less, 16% or less, 15% or less, 14% or less,
12% or less, 10% or less, 8% or less, 6% or less, 5% or less, 4% or
less or about 2% or less across the area. In one or more
embodiments, the area is about 1 square centimeter of the sintered
article, or the area is the entire surface area of the sintered
article.
Examples 5-6 and Comparative Examples 7-8
[0294] Examples 5-6 and Comparative Examples 7-8 are discrete
sintered articles formed from a continuous sintered article of
tetragonal or tetra zirconia polycrystalline material. Examples 5-6
were formed according to the process and system described herein
and Comparative Examples 7-8 were formed using other processes and
systems that do not include at least some of the presently
disclosed technology (e.g., tension control, zoned sintering
furnace, air flow control). Each of Examples 5-6 and Comparative
Examples 7-8 had length of 55.88 mm, a width of 25.4 mm, a
thickness of 0.04 mm, and a corner radius of 2 mm. Each of Examples
5-6 and Comparative Examples 7-8 had a Young's modulus of 210 GPa,
Poisson's ratio (.nu.) of 0.32, and a density (.rho.) of 6
g/cm.sup.3.
[0295] Example 5 had a c-shape as shown in FIG. 35, with 0.350 mm
shape magnitude. Example 6 had a saddle shape as shown in FIG. 36,
with 0.350 mm shape magnitude. Comparative Example 7 had a gullwing
shape with 0.350 mm shape magnitude as shown in FIG. 37.
Comparative Example 8 had a gullwing shape with 0.750 mm shape
magnitude as shown in FIG. 38. The shape magnitude of each sintered
article about the plane prior to flattening is compared in FIG.
39.
[0296] The flattenability of the Examples was evaluated using the
two loading methods otherwise described herein (i.e., pinching the
sintered articles between two rigid parallel surfaces or applying a
surface pressure on one major surface of the sintered article to
push the sintered article against a rigid surface, to flatten the
sintered article along a flattening plane).
[0297] FIG. 40 shows the force (in N) required to pinch each of the
sintered articles of Examples 5-6 and Comparative Examples 7-8 flat
to within a distance of 0.001 mm from the flattening plane, by
pinching between two rigid parallel surfaces. As shown in FIG. 40,
Examples 5-6 require significantly less force to flatten the
sintered articles, indicating a greater flattenability. Moreover,
the ability to flatten the sintered articles at such low force
indicates that such articles can be manipulated in or subjected to
downstream processing without fracturing, breaking or otherwise
forming defects. Downstream processes may include, for example, the
application of coatings which may include conductive or
nonconductive coatings. This same flattenability is also
demonstrated when the pressure required to push each of the
sintered articles of Examples 5-6 and Comparative Examples 7-8 flat
to within a distance of 0.001 mm from the flattening plane, by
pushing the sintered article against a rigid surface, was measured.
The results are shown in FIG. 41, which demonstrate Examples 5-6
require a significantly less pressure to flatten when compared to
Comparative Examples 7-8. FIG. 42 shows the maximum in plane
surface stress in the flattened sintered articles of Examples 5-6
and Comparative Examples 7-8. Examples 5-6 exhibit less than 11 MPa
of stress, while Comparative Examples 7-8 exhibit more than 20
times that stress, indicating the sintered articles of Comparative
Examples 7-8 are more likely to fracture, break or have defects
during downstream processing. The location of the stress in Example
5 is shown in FIG. 43A (bottom surface stress when flattened) and
43B (top surface stress when flattened). The location of the stress
in Example 6 is shown in FIG. 44A (bottom surface stress when
flattened) and 44B (top surface stress when flattened). The
location of the stress in Comparative Example 7 is shown in FIG.
45A (bottom surface stress when flattened) and 45B (top surface
stress when flattened). In Comparative Example 7, on the bottom
surface, the central portion exhibits a tensile stress of 208.6
MPa, which is flanked on both sides by compressive stress of -254.6
MPa. Correspondingly, on the front surface, the central portion is
under a compressive stress of about -208.6 MPa and is flanked on
both sides by a tensile stress of 254.6 MPa. The location of the
stress in Comparative Example 8 is shown in FIG. 46A (bottom
surface stress when flattened) and 46B (top surface stress when
flattened). In Comparative Example 8, on the bottom surface, the
central portion exhibits a tensile stress of 399.01 MPa, which is
flanked on both sides by compressive stress of -473.63 MPa.
Correspondingly, on the front surface, the central portion is under
a compressive stress of about -399.08 MPa and is flanked on both
sides by a tensile stress of 473.60 MPa. The high stress at the
points X in Comparative Examples 7-8 indicate these sintered
articles will likely fracture along the high stress locations.
[0298] In some semiconductor packages and similar light emitting
diode (LED) containing packages, much of the electrical energy
provided to or through the package may be lost or dissipated as
heat energy. The heat dissipation capacity of these and similar
semiconductor packages may be a limiting factor when trying to
provide additional electrical energy (or current) through the
package. Also, in at least some LED containing packages, brightness
of the LED may be limited by the heat dissipation capacity of the
LED containing package. It may be desirable to reduce and maintain
the temperature of the components in a semiconductor package, such
as from about 75.degree. C. to about 85.degree. C.
[0299] In one or more embodiments and referring to FIG. 47,
sintered article as described herein (e.g., sintered article 1000,
sintered article 1200, or sintered tape material 40) is directly or
indirectly joined, bonded, connected, or otherwise attached to a
substrate 1500 to form a package 2000. Sintered article 1000 may
act as a dielectric in package 2000. In some embodiments, package
2000 is a semiconductor package, an electrical package, a power
transmission package, a light emitting diode (LED) package, or
similar. Package 2000 of the present disclosure provides improved
performance (e.g., heat dissipation capacity, lower thermal
resistance, etc.) when compared with conventional packages. In
other such embodiments, sintered article as described herein (e.g.,
sintered article 1000, sintered article 1200, or sintered tape
material 40) is or is also substrate 1500.
[0300] In some embodiments, package 2000 includes an interlayer
1300 between substrate 1500 and sintered article 1000. Interlayer
1300 may include a material that joins, bonds, connects, or
otherwise attaches or facilitates attachment of substrate 1500 and
sintered article 1000. Interlayer 1300 may include a plurality of
discrete layers joined or joined together to form interlayer 1300.
In some embodiments, interlayer 1300 is a material with high
thermal conductivity properties such that heat generated by
electrical components (e.g., a semiconductor device or chip) or
metal-based layers is conducted through interlayer 1300 to
substrate 1500. In some embodiments, interlayer 1300 includes a
thermal conductivity greater than that of sintered article 1000. In
some embodiments, interlayer 1300 includes a thermal conductivity
less than substrate 1500. Interlayer 1300 may have a thermal
conductivity greater than about 8 W/m K to about 20 W/m K, greater
than about 8 W/m K to about 16 W/m K, or greater than about 8 W/m K
to about 13 W/m K, or greater than about 9 W/m K to about 12 W/m K,
such as 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 W/m K,
including all ranges and subranges therebetween. In some
embodiments, interlayer 1300 is an adhesive-like material. In some
embodiments, interlayer 1300 is a compliant material which is
configured to deform and/or to withstand shearing forces from
coefficient of thermal expansion (CTE) differences between
substrate 1500 and sintered article 1000 which occur as a result of
heating and cooling of package 2000.
[0301] In some embodiments, interlayer 1300 includes a matrix of a
polyimide, an epoxy, or combinations thereof. In some embodiments,
the matrix of interlayer 130 may include nonconductive particles
(e.g., boron nitride), conductive particles (e.g., silver, copper,
etc.), or combinations thereof. The conductive and/or
non-conductive particles may be homogeneously or non-homogeneously
distributed throughout the matrix of interlayer 130. In some
embodiments, interlayer 1300 conducts heat from metal-based layer
1350 and components 1401 (FIG. 50(e)) and transfers the conducted
heat to substrate 1500. In some embodiments, interlayer 1300 may
have a length (L) and a width (W) substantially similar to that of
one or both of substrate 1500 and/or sintered article 1000. In some
embodiments, interlayer may have a thickness (t.sub.2) from about
0.1 .mu.m to about 100 .mu.m, or from about 10 .mu.m to about 75
.mu.m, or from about 15 .mu.m to about 35 .mu.m, or even from about
20 .mu.m to about 40 .mu.m, such as 5, 10, 15, 20, 25, 30, 35, or
40 .mu.m, including all ranges and subranges therebetween.
[0302] In one or more embodiments, substrate 1500 includes a first
major surface 1510, a second major surface 1520 opposing the first
major surface, and a body 1530 extending between the first and
second surfaces 1510, 1520. Sintered article 1000 may be directly
or indirectly joined, bonded, connected, or otherwise attached to
first major surface 1510 or second major surface 1520 of substrate
1500. The body 1530 has a thickness (t.sub.1) defined as a distance
between the first major surface 1510 and the second major surface
1520, a width (W.sub.1) defined as a first dimension of one of the
first or second surfaces orthogonal to the thickness, and a length
defined as a second dimension of one of the first or second
surfaces orthogonal to both the thickness and the width. In one or
more embodiments, substrate 1500 includes opposing minor surfaces
1540 that define the width W.sub.1. In some embodiments, the
lengths and widths of sintered article 1000 and substrate 1500,
respectively, are substantially equivalent (e.g., the lateral
dimensions within 5% of each other). In some embodiments, the
thickness (t.sub.1) of substrate 1500 is greater than the thickness
(t) of sintered article 1000, such as the thicknesses (t) disclosed
herein for sintered article 1000. In some embodiments, the
thickness (t.sub.1) of substrate 1500 is about 25% greater than,
about 50% greater than, about 75% greater than, about 100% greater
than, about 200% greater than, about 500% greater than or more than
the thickness (t) of sintered article 1000. In some embodiments,
the thickness (t.sub.1) of substrate 1500 is from about 0.5 mm to
about 5.0 mm, or from about 1.0 mm to about 2.0 mm, or from about
1.0 mm to about 1.6 mm, or even from about 1.2 mm to about 1.5 mm.
In some embodiments, substrate 1500 acts as a heat sink for package
2000. In some embodiments, substrate 1500 comprises an electrically
conductive metal, such as aluminum, copper, or combinations
thereof.
[0303] FIGS. 47 and 48 provide cross-sectional views of a segment
of an example package 2000 in which interlayer 1300 joins substrate
1500 to sintered article 1000. A metal-based layer 1350 may be
provided on a major surface of sintered article 1000 opposite the
major surface bonded to interlayer 1300. That is, sintered article
1000 may include interlayer 1300 on one major surface and
metal-based layer 1350 on the opposite major surface. Interlayer
1300 may be applied to one or both of substrate 1500 and sintered
article 1000. Subsequently, substrate 1500 and sintered article
1000 may be assembled or joined together with interlayer 1300
between a major surface of each. Interlayer 1300 may be activated
with thermally energy, actinic wavelengths, pressure, or other
similar method to join, bond, connect, or otherwise attach
substrate 1500 to sintered article 1000 via interlayer 1300.
[0304] As illustrated in FIG. 47, one or both of major surfaces
1510, 1520 of substrate 1500 may be patterned to include grooves
1325. Grooves 1325 may assist with joining interlayer 1300 to
substrate 1500. Grooves 1325 may also help minimize sheer stresses
experienced by interlayer 1300 as a result of CTE differences
between substrate 1500 and sintered article 1000. In some
embodiments, grooves 1325 cover at least a portion of a major
surface of substrate 1500. Grooves 1325 may have a depth from about
0.1 .mu.m to about 1 mm, or from about 10 .mu.m to about 50 .mu.m
in a major surface of substrate 1500. Interlayer 1300 may extend at
least partially within grooves 1325 of substrate 1500. Grooves 1325
may be rectangular, square, circular, triangular, or other similar
shapes or combinations of several shapes in cross-section and may
be continuous, dashed, or otherwise extending on a major surface of
sintered article 1000.
[0305] Metal-based layer 1350 may be directly or indirectly joined
to sintered article 1000 by electroplating, printing, physical
vapor deposition, chemical vapor deposition, sputtering, or other
similar techniques. Metal-based layer 1350 is an electrically
conductive material capable of conducting or providing electrical
energy (or current) across and through package 2000. In some
embodiments, metal-based layer is configured to minimize electrical
resistance and heat generation across its length. In some
embodiments, metal-based layer 1350 comprises copper, nickel, gold,
silver, gold, brass, lead, tin, and combinations thereof.
Metal-based layer 1350 may be indirectly joined to sintered article
1000 via a seed layer 1375. That is, seed layer 1375 may provide a
foundation for joining metal-based layer 1350 to sintered article
1000. In some embodiments, seed layer 1375 that joins metal-based
layer 1350 to sintered article 1000 is "reflowed" in a reflow oven
to electrically connect the metal-based layer 1350 to other
electrical components in the package 2000. In some embodiments,
seed layer 1375 comprises tin, titanium, tungsten, lead, or
combinations thereof. Seed layer 1375 may be applied to a major
surface of sintered article 1000 by electroplating, printing,
physical vapor deposition, chemical vapor deposition, sputtering,
or other similar techniques.
[0306] In some embodiments, metal-based layer 1350 may be directly
or indirectly joined to sintered article 1000 before, during, or
after sintered article 1000 is joined to substrate 1500. In some
embodiments, metal-based layer 1350 is a continuous,
semi-continuous, or discontinuous array or "circuit" on a major
surface of sintered article 1000. In some embodiments, prior to
applying metal-based layer 1350 and/or seed layer 1375 on sintered
article 1000, portions of one or both major surfaces of sintered
article 1000 may be masked or covered to prevent application of
metal-based layer 1350 and/or seed layer 1375 on said masked
portions of sintered article 1000. That is, the masking portions of
one or both major surfaces of sintered article 1000 may be used to
form a semi-continuous or discontinuous array or "circuit" of
metal-based layer 1350 and/or seed layer 1375 on a major surface of
sintered article 1000. After metal-based layer 1350 is applied to
an unmasked portion of a major surface of sintered article 1000,
masking may be removed to expose that portion of the major surface
(without a metal based layer and/or seed layer thereon) where the
masking was present. FIGS. 47 and 49 provide examples of
metal-based layer 1350 as an array on a major surface of sintered
article. Metal-based layer 1350 includes a thickness (t.sub.3) from
about 0.1 .mu.m to about 1 mm, or from about 2 .mu.m to about 100
.mu.m, from about 5 .mu.m to about 70 .mu.m, or even from about 5
.mu.m to about 50 .mu.m.
[0307] In one or more embodiments, package 2000 includes a
semiconductor device or chip 1400. In some embodiments,
semiconductor device 1400 is directly or indirectly joined, bonded,
connected, or otherwise attached to first major surface 1010 or
second major surface 1020 of substrate 1000. Semiconductor device
1400 may be indirectly joined to sintered article 1000 via seed
layer 1375 as shown in FIG. 49. Semiconductor device 1400 may
include one or more light emitting diodes (LED). In some
embodiments, semiconductor device 1400 is connected to metal-based
layer 1350 by one or more leads 1450. Leads 1450 may be rigid or
flexible wires or electrical connectors (e.g., similar to the
metal-based layer 1350) that electrically connect semiconductor
device 1400 and metal-based layer 1350. FIGS. 47 and 49 illustrate
lead 1450 as bridging the distance between semiconductor device
1400 and metal-based layer 1350. Of course, leads 1450 may run
along or contact the surface of sintered article 1300 in one or
more embodiments. Leads 1450 may provide electrical energy between
metal-based layer 1350 and semiconductor device 1400. In some
embodiments, electrical energy running through metal-based layer
1350 is transmitted through leads 1450 to semiconductor device
1400. In some embodiments, electrical energy provided to
semiconductor device 1400 powers an LED thereon which emanates one
or more light wavelengths (.lamda.). Semiconductor device 1400 may
include one or more lenses 1405 to intensify or directly light from
LEDs thereon. Semiconductor device 1400 may also include a phosphor
material 1475 to filter and transmit specific wavelengths (.lamda.)
therethrough from light wavelengths (.lamda.) emanating from the
LEDs.
[0308] In one or more embodiments, methods of making package 2000
include providing sintered article 1000. Sintered article 1000 may
be in on a roll including a round or cylindrical core having a
diameter of less than 60 cm, the continuous sintered article wound
around the core. Sintered article 1000 may also be provided as
discrete flattened lengths. In one or more embodiments, methods of
making package 2000 include providing a carrier or temporary
substrate 1499 (FIG. 50), which may be on a roll or as a large,
flat sheet. In some embodiments, a length of sintered article 1000
is joined, bonded, connected, or otherwise attached to a length of
carrier or temporary substrate 1499 to form precursor package 1999.
Carrier or temporary substrate 1499 may support the sintered
article 1000 for subsequently rolling onto a core. In some
embodiments, carrier or temporary substrate 1499 supports sintered
article 1000 during subsequent processes which may damage, degrade,
or destroy substrate 1500. In some embodiments, carrier or
temporary substrate 1499 comprises glass, a polymer, or
combinations thereof. In some embodiments, carrier or temporary
substrate 1499 is polymeric, such as a polyamide tape.
[0309] In some embodiments, precursor package 1999 includes a
precursor interlayer 1299 (FIG. 50) between sintered article 1000
and temporary substrate 1499. Precursor interlayer 1299 may include
a material that joins, bonds, connects, or otherwise attaches
temporary substrate 1499 and sintered article 1000. In some
embodiments, precursor interlayer 1299 is a high-temperature
resistant adhesive. Precursor interlayer 1299 may be activated with
thermal energy, actinic wavelengths, pressure, or other similar
method to join, bond, connect, or otherwise attach temporary
substrate 1499 to sintered article 1000. In some embodiments,
precursor interlayer 1299 may be deactivated by similar or
different means than that for activation so that sintered article
1000 can be detached or disconnected from temporary substrate 1499.
In some embodiments, precursor interlayer 1299 and temporary
substrate 1499 are configured to withstand (not degrade) during
subsequent processing of precursor package 1999, including
application of metal-based layer 1350, seed layer 1375,
semiconductor device 1400, leads 1450, and/or other similar
components.
[0310] FIG. 50 illustrates a method of forming package 2000 from a
precursor package 1999. Step (a) in the FIG. 50 illustrates
precursor package 1999 following applying metal-based layer 1350 on
a major surface of sintered article 1000 opposite the surface
joined with precursor interlayer 1299. Step (a) in FIG. 50 also
illustrates precursor package 1999, following removing masking from
sintered article 1000 (e.g., between metal-based layers 1350).
Before or after step (a), seed layer 1375 may be applied to
sintered article 1000. Step (b) in FIG. 50 illustrates applying
parts (i.e., semiconductor device 1400 and leads 1450) of
components 1401 to sintered article 1000 to electrically connect
semiconductor device 1400 and metal-based layer 1350. In some
embodiments, carrier or temporary substrate 1299 and precursor
interlayer 1299 are configured to support sintered article 1000 and
not degrade or deform during steps (a) and (b) illustrated in FIG.
50, which may be completed at high temperatures (e.g., up to or
greater than 320.degree. C.). Step (c) in FIG. 50 illustrates
separating sintered article 1000 (including metal-based layer 1350,
semiconductor device 1400, and leads 1450 thereon) from temporary
substrate 1499. In some embodiments, step (c) may be completed by
deactivating precursor interlayer 1299 with thermal energy, actinic
wavelengths, pulling, or other similar method. In some embodiments,
sintered article 1000 (including metal-based layer 1350,
semiconductor device 1400, and leads 1450 thereon) is pulled from
temporary substrate 1499 by a machine or by hand. In some
embodiments, step (c) occurs in a reflow furnace while seed layer
1375 or solder electrically connects the parts of component 1401.
Precursor interlayer 1299 may transfer with sintered article 1000,
with temporary substrate 1499, or with both (a portion on each).
Step (c) in FIG. 50 illustrates an embodiment where precursor
interlayer 1299 is transferred with temporary substrate 1499. In
some embodiments, precursor interlayer 1299 may become interlayer
1300 in subsequent processing (e.g., heating) or by bonding or
contacting substrate 1500. Step (d) in FIG. 50 illustrates joining
sintered article 1000 and substrate 1500 with interlayer 1300
therebetween. In some embodiments, precursor interlayer 1299 may be
the same as interlayer 1300. Step (e) in FIG. 50 illustrates
applying additional parts (e.g., lens 1405 and phosphor 1475) of
components 1401 to sintered article 1000. In some embodiments,
parts of components 1401 may be applied at lower temperatures
(e.g., <150.degree. C.) such that interlayer 1300 and substrate
1500 are not degraded or deformed while completing the building of
components 1401. Package 2000 as shown in step (e) of FIG. 50 may
include one or more of components 1401.
[0311] FIG. 51 provides another illustrative method of forming
package 2000 via a precursor package 1999. Step (a) of FIG. 51
illustrates providing flattened sintered article 1000 from a rolled
core, as flattened sheets, or otherwise. Step (b) of FIG. 51
illustrates joining the flattened sintered article 1000 and carrier
or temporary substrate 1499 to form precursor package 1999.
Precursor interlayer 1299 or a similar such layer may be located
between sintered article 1000 and carrier or temporary substrate
1499. Precursor package 1999 may be rolled onto a core, stored,
shipped, or sold for subsequent processing. Step (c) of FIG. 51
illustrates applying metal-based layer 1350 and the parts (e.g.,
semiconductor device 1400, leads 1450, lens 1405, phosphor 1475,
etc.) of light-emitting components 1401 to sintered article 1000.
Step (c) may include several stages which electrically connect
metal-based layer 1350 with semiconductor device 1400 and any LEDs
thereon on sintered article 1000. Step (c) may also include a
solder reflow operation in a solder furnace to electrically connect
all the parts of components 1401. Step (d) of FIG. 51 illustrates
detaching or separating sintered article 1000 (including components
1401) and temporary substrate 1499. Step (d) may be accomplished by
pulling sintered article 1000 (including components 1401) from
temporary substrate 1499 by a machine or by hand. Step (d) may be
catalyzed by heat, exposure to actinic wavelengths, cooling,
exposure to solvents, or other similar methods. Of course,
precursor interlayer 1299 (if present) may transfer with sintered
article 1000, with temporary substrate 1499, or with both (a
portion on each). Step (e) of FIG. 51 illustrates joining sintered
article 1000 (including components 1401) and substrate 1500 to form
package 2000. In some embodiments, sintered article 1000 (including
components 1401) and substrate 1500 may be joined by interlayer
1300 or a similar layer therebetween to form package 2000. Step (f)
of FIG. 51 illustrates cutting package 2000 at different points
along its length L.sub.4 into a plurality of segments 2001. Package
2000 may be cut along its length L.sub.4 into segments 2001 with
localized cutting pressure, laser energy (e.g., UV ablation laser),
or with similar techniques. In some embodiments, each segment 2001
includes at least one or more components 1401. Segments 2001 of
package 2000 may be used in a variety of applications including as
a filament for a light bulb, an electronic device, a handheld
device, a heads-up display, a vehicle instrument panel, or
similar.
[0312] FIGS. 52-54 illustrate cross-sectional views of package 2000
including sintered article 1000 and a "flip-chip" configuration of
semiconductor device 1400. In these embodiments, a segment of
package 2000 may include an aperture 1501 in substrate 1500.
Aperture 1501 may be formed by drilling, cutting, or removing part
of substrate 1500. Aperture 1501 may also be formed by spacing two
parts of substrate 1500 apart on one major surface of sintered
article 1000. In some embodiments, metal-based layer 1350 may be
joined, bonded, connected, or otherwise attached to the same major
surface of sintered article 1000 as substrate 1500.
[0313] FIG. 52 illustrates an example cross-sectional views of a
segment of package 2000 including sintered article 1000 joined with
substrate 1500. In some embodiments, metal-based layer 1350 is
provided within aperture 1501. That is, metal-based layer 1350 is
joined on the same major surface of sintered article 1000 as
substrate 1500. In some embodiments, seed layer 1375 is applied to
and bonded with metal-based layer 1350. Seed layer 1375 may assist
with bonding metal-based layer 1350 and semiconductor device 1400
in a "flip-chip" configuration. In one or more embodiments, seed
layer 1375 comprises tin, titanium, tungsten, lead, or alloys
thereof. In some embodiments, seed layer 1375 is electrically
conductive and may eliminate the need for leads to electrically
connect metal-based layer and semiconductor device 1400. In some
embodiments, a volume 1485 may be formed between sintered article
1000 and semiconductor device 1400. Together with metal-based layer
1350 and/or seed layer 1375, volume 1485 may be sealed between
sintered article 1000 and semiconductor device 1400. In some
embodiments, an LED on semiconductor device 1400 is opposite volume
1485 and within aperture 1501. In some embodiments, an LED on
semiconductor device 1400 is within volume 1485. Phosphor material
1475 may be provided within volume 1485. In the FIGS. 52 and 53,
sintered article 100 may be translucent or substantially
transparent such that light wavelengths (.lamda.) emanating from an
LED on semiconductor device 1400 transmits through sintered article
1000. In some embodiments, sintered article 1000 may transmit from
about 35% to about 95%, or from about 45% to about 85%, or from
about 55% to about 75%, such as 35%, 40%, 50%, 60%, 65%. 75%, 85%,
90%, 95%, or more up to 99%, including all ranges and subranges
therebetween, of some, most, or all the visible light wavelengths
(.lamda.) emanating from an LED or transmitted through phosphor
material 1475.
[0314] The total light transmitted (T) through the sintered article
1000 may be defined by the follow equation 1:
T=.PHI..sub.e.sup.t/.PHI..sub.e.sup.i (1)
[0315] where,
[0316] .PHI..sub.e.sup.t is the radiant flux transmitted by that
surface; and
[0317] .PHI..sub.e.sup.i is the radiant flux received by that
surface.
The measurement of these quantities is described in ASTM standard
test method D1003-13.
[0318] Although similar to FIG. 52, FIG. 53 illustrates interlayer
1300 between sintered article 1000 and substrate 1500. FIG. 53
further illustrates an embodiment where at least a portion of
aperture 1501 (shown in FIG. 52) is plugged with substrate 1500
which may be isolated from or connected with adjacent portions of
substrate 1500. In other embodiments, at least a portion of
aperture 1501 is plugged with a filler material (e.g., epoxy,
plastic, polymeric material, etc.) to seal chip 1400 and
metal-based layer 1350 within package 2000. In FIG. 53, substrate
1500 contacts semiconductor device 1500 to conduct heat from
semiconductor device 1400 generated when electrical energy is
provided to package 2000. In some embodiments, sintered article
1000 includes a hole 1490 through its thickness. As illustrated in
FIGS. 53 and 55, hole 1490 in sintered article 1000 intersects
volume 1485. Hole 1490 may allow phosphor material 1475 within
volume 1485 to be cooled by ambient convection. Hole 1490 may also
allow light wavelengths (.lamda.) from an LED in volume 1485 to
emanate from package 2000. As shown in FIG. 54, a reflector 1480
may be included within volume 1485 and/or hole 1490 to intensify or
reflect light wavelengths (.lamda.) emanating from an LED on
semiconductor device 1400. Reflector 1480 may have a conical, a
hemispherical, a tapering, or a curved shape. In some embodiments,
reflector 1480 may be coated with a coating to intensify light
wavelengths (.lamda.) emanating from an LED on semiconductor device
1400. FIG. 55 shows another possible configuration.
[0319] In one or more embodiments, the sintered articles described
herein may be used in microelectronics applications or articles.
For example, such microelectronics articles may include a sintered
article (according to one or more embodiments described herein)
including a first major surface, a second major surface opposing
the first major surface. In one or more embodiments, the
microelectronics article may include a continuous (e.g., long tape,
as described herein) or discrete (e.g., sheets cut or singulated
from a tape) sintered article. In one or more embodiments, the
microelectronics article includes a continuous or discrete sintered
article having a width of about 1 mm or greater, about 1 cm or
greater, about 5 cm or greater, or about 10 cm or greater. In one
or more embodiments, the microelectronics article includes a
sintered article having a length of about 1 m or greater, 5 m or
greater, or about 10 m or greater. In one or more embodiments, the
microelectronics article includes a continuous or discrete sintered
article having a thickness of less than 1 mm, about 0.5 mm or less,
about 300 micrometers or less, about 150 micrometers or less, or
about 100 micrometers or less. In one or more embodiments of a
microelectronic article includes a sintered article having a
crystalline ceramic content by volume of about 10% or greater,
about 25% or greater, 50% or greater, about 75% or greater, or
about 90% or greater.
[0320] In one or more embodiments, the sintered article includes
one or more vias (e.g., holes, apertures, wells, pipes, passages,
linkages; see hole 1490 of FIG. 53) disposed along a given area of
the first major surface of the sintered article. In one or more
embodiments, the vias partially or wholly extend through the
thickness of the sintered articles. In one or more embodiments, the
vias may be disposed in a pattern that may be repeating or
periodic, such as where the vias are formed along the tape in a
continuous roll-to-roll process, where the tape may later be
singulated to form individual components, such as for
semiconductors or other electronics. In one or more embodiments,
the vias may be spaced from one another such that there is a
distance of about 0.5 m or less, 10 cm or less, or 5 cm or less
between the vias (i.e. at least between some, most, or each via and
the next closest via). In some embodiments, this via spacing may be
present in sintered articles having a thickness of less than 1 mm,
about 0.5 mm or less, about 300 micrometers or less, about 150
micrometers or less, or about 100 micrometers or less. In one or
more specific embodiments, this via spacing may be present in
sintered articles having a thickness of about 50 micrometers or
less. Vias may be cut by laser, masks and etchants, punch, or other
methods, such as prior to, during (e.g., when partially sintered)
or after sintering. Forming vias after sintering may help precision
of placement and sizing of the vias; however due to the consistency
of processes and materials described herein, vias may be formed in
green tape or partially sintered tape for example, and accuracy of
placement, sizing, wall geometry, etc. may be within desired
tolerances for some applications.
[0321] In one or more embodiments, the sintered article includes a
conductive layer (e.g., copper, aluminum, or other conductive
layer; see generally layer 1350 of FIG. 47) disposed on the first
major surface, the second major surface, or both the first major
surface and the second major surface. In one or more embodiments,
the conductive layer partially or wholly covers the major surface
on which it is disposed, such as overlaying at least 20% of the
respective surface, at least 40%, at least 60%, at least 80%. In
other words, the conductive layer may form a continuous layer on
the entire area of the surface on which it is disposed or may form
a discontinuous layer on the surface on which itis disposed. The
conductive layer may form a pattern that may be repeating or
periodic, such as for not-yet-singulated semiconductor components
formed on a tape. In one or more embodiments, the sintered article
may include one or more additional layers disposed on top of the
conductive layer or between the conductive layer and the sintered
article, and/or intermediate to the conductive layer and the tape
(or other sintered article as disclosed herein). Such one or more
additional layers may partially or wholly covers the surface on
which it is disposed (i.e., a major surface of the sintered article
or the conductive layer), such as according to the percentages
described above for the conductive layer. In other words, the one
or more additional layers may form a continuous layer on the entire
area of the surface on which it is disposed or may form a
discontinuous layer on the surface on which it is disposed. The one
or more additional layers may form a pattern that may be repeating
or periodic. In some embodiments, the one or more additional layers
may also be conductive layers, dielectric layers, sealing layers,
adhesive layers, surface-smoothing layers, or other functional
layers. In some embodiments, the conductive layer and, optionally,
the one or more additional layers, may be present in sintered
articles having a thickness of less than 1 mm, about 0.5 mm or
less, about 300 micrometers or less, about 150 micrometers or less,
about 100 micrometers or less or about 50 micrometers or less.
Accordingly, the layers and the sintered article may be flexible,
and/or may be rolled onto a roll or spool as disclosed herein.
[0322] In some embodiments, the sintered article may include two or
more of a plurality of vias, a conductive layer and one or more
additional layers.
[0323] In one or more embodiments, system 10 for producing a
sintered tape article may include a fabrication system for further
processing a green tape, partially sintered articles, and/or
sintered articles described herein for use in a microelectronics
article. In one or more embodiments, the fabrication system may be
disposed downstream of the binder burn out furnace 110 but upstream
of the sintering station 38 to process tape without binder, or
after the sintering station 38 to process a partially sintered
article or before the furnace 110 to process the green tape, which
would then be sintered as otherwise described herein. In one or
more embodiments, the fabrication system may be disposed downstream
of the sintering station 38 but upstream of the uptake system 42 to
process a sintered article. In one or more embodiments, the
fabrication system may be disposed downstream of the uptake reel 44
but upstream of the reel 48, to process a sintered article. In one
or more embodiments, the fabrication system may be disposed
downstream from the reel 48 to process a sintered article. In such
embodiments, the fabrication system would process the green tape
material, partially sintered article or sintered article when it is
continuous (and not discrete). Other configurations are possible to
process the sintered article as a discrete article.
[0324] In one or more embodiments, the fabrication system may
expose at least a portion of the green tape material, partially
sintered article or sintered article to a mechanism for forming
vias, such as laser energy, or a drill. The fabrication system of
one or more embodiments using laser energy to create the vias may
include a hug drum (see generally vacuum drum 25 of FIG. 6) having
a surface with a curvature, wherein the hug drum pulls the green
tape material, partially sintered article or sintered article to
the match its curvature to facilitate formation of the vias on the
major surface of the sintered article. In one or more embodiments,
the hug drum would facilitate focus of the laser beam on the major
surface of the green tape material, partially sintered article or
sintered article.
[0325] In one or more embodiments, the vias may be created by
mechanical means. For example, the fabrication system may include a
flat plate on which a portion of the green tape material, partially
sintered article or sintered article is temporarily secured. In
this manner, one major surface of the green tape material,
partially sintered article or sintered article is in contact with
the flat plate. The conveyance of the green tape material,
partially sintered article or sintered article to the fabrication
system may use a step and repeat motion, acceleration or
deceleration velocity, or continuous velocity to allow for a
portion of the sintered article to be temporarily secured to the
flat plate. In one or more embodiments, a vacuum may be used to
temporarily secure a portion of the green tape material, partially
sintered article or sintered article to the flat plate.
[0326] In one or more embodiments, fabrication system may form vias
by mechanically separating a portion of the green tape material,
partially sintered article or sintered article. In one or more
embodiments, the fabrication system may include the use of
photolithography, with solvents or acids to remove a portion of the
green tape material, partially sintered article or sintered
article. In such embodiments, when the fabrication system is
applied to green tape material or partially sintered articles, the
fabrication system may include a control mechanism for controlling
the scale and pattern scale of the vias, due to shrinkage of the
green tape material or partially sintered article when it is fully
sintered. For example, the control mechanism may include a sensor
at the outlet of the sintering station 38 that measures the
distance between the vias and the spacing of the vias and feedback
this information to the fabrication system for adjustment. For
example, if the fabrication system was forming vias having a
diameter of about 75 micrometers, and a distance or pitch of 500
micrometers between the vias, and it was assumed that the full
sintering shrinkage from the green tape material to the sintered
article was 25%, then the fabrication system would or may adjust to
form the vias in the green tape material to have a pitch of 667
microns and a diameter of about 100 micrometers. After processing,
the full sintering shrinkage is measured to be 23% then, the
fabrication system could further adjust to the correct spacing for
the vias in the green tape material would be 649 microns, to
accommodate for 23% full sintering shrinkage. Vias in some
embodiments have a widest cross-sectional dimension (coplanar with
a surface of the sheet or tape) that is at least 250 nm, such as at
least 1 .mu.m, such as at least 10 .mu.m, such as at least 30
.mu.m, such as at least 50 .mu.m, and/or no more than 1 mm, such as
no more than 500 .mu.m, such as no more than 100 .mu.m. In some
embodiments, the vias are filled with an electrically conductive
material, such as copper, gold, aluminum, silver, alloys thereof,
or other materials. The vias may be laser cut, laser and etchant
formed, mechanically drilled, or otherwise formed. The vias may be
arranged in a repeating pattern along a sheet or tape, which may
later be singulated into individual electronics components.
[0327] FIG. 104 shows an example in cross-section of a stacked
arrangement 810 of ceramic sheets 812 with vias 814 extending to
metal layers 816. Fiducial 818 may help align the sheets 812.
[0328] The system 10 described herein provides other ways to
control via spacing during the sintering process. For example,
tension in the processing direction 14 during sintering can stretch
the sintering article and bias the sintering shrinkage. This
tension can increase the spacing of the vias in the processing
direction 14, effectively reducing the sintering shrinkage in the
processing direction 14. Differential sintering in the processing
direction 14 as opposed to the direction perpendicular to the
processing direction 14 has been observed, and can be in a range
from about 2% to about 3%, when tension is applied. Accordingly,
some otherwise round vias may be oval or oblong.
[0329] The size and shape of the vias can be controlled and
adjusted with a combination of the sintering shrinkage along the
direction parallel to the processing direction 14, sintering
shrinkage across the direction perpendicular to the processing
direction 14, tension in the two directions and the shape of the
sintering station 38 and/or through use of air bearings to
transport the green tape material, the partially sintered article
or the sintered article while sintering or hot.
[0330] In one or more embodiments, ceramic material may be added at
any step within the system 10 to decrease the sintering shrinkage.
Ceramic material can be added by ink jet print heads, which can
apply such ceramic material uniformly to a porous partially
sintered article or sintered article, while such articles have open
porosity. In one or more embodiments, small amounts of ceramic
material can be added to the porous partially sintered article or
sintered article by printing. Lasers, photolithography, ink jets,
atomic layer deposition, and some printing and other processing
means can be accomplished from the inner radius of a curved air
bearing or with a sectioned hug drum with open areas for the
exposure of the partially sintered article or sintered article to
the processing equipment. Accordingly, tape or other articles as
disclosed herein may be or include a portion thereof of two or more
co-fired inorganic materials (e.g., ceramics or phases), such as
where one of the materials infiltrates and fills pores of the other
material. In contemplated embodiments, the filling/infiltrating
material may be chemically the same as the porous material, but may
be distinguishable in terms of crystal content (e.g., grain size,
phase).
[0331] In one or embodiments, vias can be formed on sintered
article having with patterns of conductor layers on one or both
sides. The conductor layer(s) can be printed or patterned (screen
printing, electroless deposition, etc.) after via formation and
final sintering. In one or more embodiments, the conductor layer(s)
but can also be printed or deposited prior to final sintering of
the sintered article. In some sintering processes that sinter only
discrete pieces (and not continuous ribbons) small sheets (e.g.,
having length and width dimensions of about 20 cm by 20 cm), the
conductor layer(s) are printed after via formation, and/or but on
green tape material only. For multi-layer substrates, individual
green tape layers are or may be aligned and laminated, with some
multi-layer substrates using as many as 30-40 green tape layers.
Alumina with tungsten, molybdenum or platinum conductors may be
co-sintered and form low firing ceramic packages based on
cordierite (glass ceramics) using conductors based on copper. In
some embodiments described herein, conductive layer(s) may be
formed (i.e., by printing or deposition) prior to the final
sintering step, and the technology disclosed herein may help
control the dimensions of the vias and conductor patterns during
the sintering steps.
[0332] Moreover, the continuous sintering processes and system 10
offers means to control the vias spacing and patterns and
conductive layer(s) patterns in terms of spacing during the
sintering process. Tension in the processing direction during the
sintering can stretch the green tape material, partially sintered
article, or sintered article and/or bias the sintering shrinkage as
disclosed above. This tension can increase the vias spacing and
patterns and conductive layer(s) patterns in the processing
direction, effectively reducing the sintering shrinkage in the
process direction. Differential sintering in the processing
direction versus the direction perpendicular to the processing
direction may range from about 2% to about 3%, such as where tape
is stretched in the processing or lengthwise direction.
[0333] Controlled curvature sintering station 38 or curved air
bearings can be used to transport the green tape material,
partially sintered article, or sintered article in the processing
direction 14 and may prevent the green tape material, partially
sintered article, or sintered article from having excessive
curvature across the width of the green tape material, partially
sintered article, or sintered article. If there is a mild
cross-ribbon- or sheet-curvature, the tension in the direction
parallel to the processing direction may provide some tension
perpendicular to the processing direction, controlling or limiting
distortion.
[0334] Providing tension to the direction perpendicular to the
processing direction 14 can be difficult, particularly at the
temperatures where the sintered article is plastically deformable
and/or is sintering and plastically deformable. Rollers (see, e.g.,
FIG. 88B) angled away from a direction parallel to the processing
direction 14 in such regions of the system 10 (or particularly
sintering station 38) can apply some tension perpendicular to the
processing direction 14 (e.g., in a widthwise direction of tape).
This tension may increase the spacing of the vias perpendicular to
the processing direction 14, effectively reducing the sintering
shrinkage perpendicular to the processing direction 14.
[0335] Fiducial marks for alignment can be made by lasers,
mechanical means, chemical means such as slight composition changes
with visible results. These marks help align further processing
steps such as conductor printing, patterning, and/or
laminating.
[0336] Another aspect of this disclosure pertains to a multi-layer
sintered article having a width of about 1 mm or greater, 1 cm or
greater, 5 cm or greater, 10 cm or greater, or 20 cm or greater,
with a length of 1 m or greater, 3 m or greater, 5 m or greater, 10
m or greater, or 30 m or greater, where the sintered article has a
thickness of less than 1 mm, less than about 0.5 mm, less than
about 300 microns, less than about 150 microns, less than about 100
microns. In one or more embodiments, the sintered article has a
crystalline ceramic content of more than 10% by volume, more than
25% by volume, more than 50% by volume, more than 75% by volume, or
more than 90% by volume. The article has at least two layers of
sintered articles and may have more than 40 such layers. The
sintered article layers have at thickness of 150 microns or less,
100 microns or less, 75 microns or less, 50 microns or less, 25
microns or less, 20 microns or less, 15 microns or less, 10 microns
or less, 5 microns or less, and/or such as at least 3 microns (i.e.
at least 3 micrometers). In one or more embodiments, the sintered
article layers need not be the same composition and some such
layers include glass. In some embodiments, such glass layers may
include 100% glass, such as at least 100% amorphous silicate
glass.
[0337] In one or embodiments, the multi-layer sintered article
includes a plurality of vias, conductive layer(s) and/or optional
additional layers, as described herein with respect to
microelectronics articles.
[0338] In one or more embodiments, the system 10 may include a
process and an apparatus to make such multi-layer sintered
articles. The multi-layer can be made by casting or web coating
multiple layers of green tape material (i.e., with ceramic
particles with polymer binder) over one another. The multi-layer
green tape material structure may then be processed through the
system 10 as described herein. In one or more embodiments, the
multi-layer green tape material structure can also be formed by
laminating multiple green tapes with ceramic particles at near room
temperature in a continuous fashion and then by feeding the
laminated tapes into the system 10. Partially sintered articles can
also be laminated together with minor pressure in the sintering
station 38. The pressure can be caused by having a mild curvature
in the sintering station 38 that the partially sintered articles
are drawn across. Each partially sintered article can have its own
tensioning and payout speed control means. Each partially sintered
article can have fiducial marks to assist alignment of the
articles. Tension and payout speed can be used to match sintering
shrinkage from article to article to align vias and conductors from
article to article. If the fiducial marks are not aligned as the
multi-layer article exits the furnace, the layer payout speeds
and/or tensions can be adjusted to bring the layers back into
alignment. Additional pressure normal to the length and width of
multi-layer articles can be provided by rollers at high temperature
as described above.
[0339] As electrical conductors and ceramic materials in
multi-layer electronic substrates may not have the same thermal
expansion coefficient, some designs may provide for an overall
stress reduction (balance) for "top" side to "bottom" side of the
multi-layer sintered articles. In essence such designs have a
similar amount of metal or ceramic on the top and bottom of the
multi-layer, such as by mirroring the layers about a central plane
in the respective stack. With thin ceramic layers, a structure that
is not stress/CTE balanced may experience deformation of the
ceramic and/or curling of the overall stacked structure.
[0340] In one or more embodiments, a circuit board for electronics
comprises a sintered article, as described herein, having
electronic conductors patterned on it. The conductors for the
circuit board may be directly printed onto the green tape material,
the partially sintered article, or the sintered article and/or may
be printed onto a coating(s) or layer(s) bonded to the green tape
material, the partially sintered article, or the sintered article,
such as an adhesion promoting layer, a surface smoothing layer,
and/or other functional layers. The printing can be from a direct
screen printing, electroless deposition and pattering, lithography,
using a silicone carrier intermediate between the pattern formation
and the application of the pattern on the sintered article by
gravure patterning rollers, and/or by other processes.
[0341] The conductors for the circuit board can be directly printed
on the partially sintered article, after an intermediate firing
step but before the final sintering, and/or printed onto coatings
thereon. Porosity in the partially sintered article or sintered
article can improve adhesion of the conductor print or pattern. The
printing can be from a direct screen printing, lithography, using a
silicone carrier intermediate between the pattern formation and the
application of the pattern on the ceramic by gravure patterning
rollers, or other processes.
[0342] One aspect of the process and apparatus may be to use a hug
drum while simultaneously patterning the long continuous porous
ceramic ribbon or sheet. The hug drum pulls the ceramic ribbon or
sheet to match the curvature on the surface of the drum, making
printing of the conductor pattern less difficult. Photolithography
can also be used with solvents or acids to etch or wash away some
of the conductor pattern on the green ribbon or sheet prior to
final sintering, photolithography can be accomplished on a hug
drum. When the conductor is patterned prior to final sintering, a
means to control the pattern, size, scale, or pitch with the
sintering shrinkage is advisable. Unfortunately, sintering
shrinkage of a ceramic ribbon or sheet can vary by a percent or
more from one continuous green ribbon (or sheet) to another
continuous green ribbon (or sheet), sometimes even within a single
green ribbon or sheet. One method to insure an accurate spacing of
the conductor pattern is to have a sensor at the outlet of the
final sintering step and measure the distance of the conductor
pattern spacing. This information can be feed to the printing
pattern means (e.g., laser, drill, punch, etch system),
photolithography exposure means (e.g., radiation or light source,
mask), to adjust the conductor pattern in the pre-final sintered
ribbon or sheet to match the current sintering shrinkage. (The
length of the ribbon or sheet between the measuring means and the
"patterning" means may not be perfectly precise, however may be
more accurate than either batch sintering with a periodic kiln or
use of a tunnel kiln, such as where a great deal of final product
may be lost due to inaccuracy.)
[0343] Continuous sintering (e.g., roll to roll sintering,
continuous fired ceramic) offers another means to control the via
spacing during the sintering process. Tension in the web transport
direction (i.e. lengthwise direction for a tape) provided during
the sintering can stretch the sintering article (e.g., ribbon or
sheet) and/or bias the sintering shrinkage. This tension can
increase spacing of the conductor pattern in the ribbon or sheet
transport direction, effectively reducing the sintering shrinkage
in the ribbon transport direction. Differential sintering in the
ribbon transport direction versus the direction perpendicular to
the ribbon transport direction has been observed, up to 2 to 3%
when tension is applied.
[0344] Photolithography, ink jets, atomic layer deposition, some
printing and other processing means can be accomplished from the
inner radius of a curved air bearing or with a sectioned hug drum
with open areas for the exposure of the ceramic ribbon or tape to
the conductor pattering processing equipment.
[0345] Alumina with tungsten, molybdenum or platinum conductors may
be co-sintered with other inorganic materials disclosed herein and
form low firing ceramic packages based on cordierite (glass
ceramics) using conductors based on copper.
[0346] Controlled curvature kiln furniture or curved air bearings,
that the ceramic ribbon or web with a conductor pattern is pulled
through or over, can keep the ceramic ribbon or sheet with a
conductor pattern from having excessive curvature across the short
length of the ribbon perpendicular to the ribbon transport
direction in some such embodiments.
[0347] Providing tension to the direction perpendicular to the
ribbon transport direction, (cross web direction), can be
difficult, particularly at the temperatures where the ceramic
ribbon with conductor pattern is plastically deformable or is
sintering and plastically deformable. Rollers angled away from
parallel to the ribbon transport direction in the hot zones of the
furnace can apply some tension perpendicular to the ribbon
transport direction. This tension can increase the spacing of the
vias perpendicular to the ribbon transport direction, effectively
reducing the sintering shrinkage perpendicular to the ribbon
transport direction. The size and pitch of the conductor patterns
can be controlled and adjusted with a combination of the sintering
shrinkage along the direction parallel to the ribbon transport
direction (long length of the ceramic ribbon), sintering shrinkage
across the direction perpendicular to the ribbon transport
direction, tension in the two directions and the shape of the kiln
furnace and/or air bearing that the ceramic ribbon or sheet is on
while sintering or hot.
[0348] Fiducial marks for alignment can be made by lasers,
mechanical means, chemical means such as slight composition changes
with visible results. These marks help align further processing
steps such as conductor printing/patterning and laminating.
[0349] Multi-layer structures with ceramic and conductor may be
bonded at high temperature from final sintered conductor plus
ceramic sheets or ribbons with fewer layers, even from sheets with
only a single ceramic plus conductor layer.
[0350] Thin circuit boards with ceramic insulator layers benefit
from having a stress balance from top to bottom. This may be
accomplished by having a patch or pattern of material printed on
the side opposite to the desired conductor pattern that can
alleviate the coefficient of thermal expansion CTE or thermal
expansion related stress between the conductor and ceramic (and
sometimes a sintering differential stress between the conductor and
the ceramic). This may take the form of a second conductor layer
with a similar thickness and mass of material on the bottom of the
board, which balances the CTE stress (and sintering differential
stress) from top to bottom leaving the circuit board almost flat,
rather than curled.
[0351] As the multi-layer structure and/or the circuit board
becomes thicker, it becomes stiffer after full sintering.
Particularly with 1 mm, 0.5 mm, and 250 micron thickness ceramic
and conductor structures, rolling the article on small rolls of 30
to 7.5 cm in diameter can be problematic. Means for cutting the
continuously sintered articles by laser, diamond saw, abrasive jet,
water jet and other techniques can be adapted to the continuous
sintering apparatus, such as where individual or groups of
structures may be cut into sheets. The cutting apparatus may be
added to the exit of the final sintering furnace, and the cutting
means would travel or interface with the long article, such as
while it is exiting the furnace.
[0352] Referring to FIGS. 56 and 57, a process for initiation of
sintering and threading of green tape 20A through binder removal
station 34A and through sintering station 38A of a system 1500A for
producing a sintered tape article is shown according to an
exemplary embodiment. In general, system 1500A is substantially the
same as and functions the same as system 10 discussed above, except
for slightly different, alternative reel arrangements/positioning
in separation system 12A, tension control system 32A and uptake
system 42A.
[0353] To initiate the reel to reel transfer of tape material from
source reel 16A to uptake reel 44A, green tape 20A needs to be
threaded through the channels of binder removal station 34A and
through sintering station 38A in order for the green tape 20A to be
connected to uptake reel 44A which applies the tension to pull
green tape through binder removal station 34A and through sintering
station 38A. Similarly, if during operation of binder removal
station 34A and sintering station 38A the tape material breaks
(which may occur following binder removal), the tape material needs
to be threaded through binder removal station 34A and then through
sintering station 38A while these stations are at full operating
temperature. Applicant has determined that threading, particularly
when binder removal station 34A and sintering station 38A are at
temperature, can be particularly challenging due to the difficulty
in threading unbound tape 36 (shown in FIG. 3) (i.e., the
self-supporting tape material following removal of the organic
binder) through sintering station 38A following binder removal.
Thus, it should be understood that while the discussion of the
threading process and system discussed herein relates primarily to
threading green tape 20A, the threading process can be used to
thread a variety of tape materials, including unbound tape 36
(shown in FIG. 3) and/or partially sintered tape material, through
a sintering system such as system 10 or system 1500A.
[0354] As will be discussed in more detail below, Applicant has
developed a process utilizing a threading material or leader to
pull green tape 20A through binder removal station 34A and
sintering station 38A in order to initiate the reel to reel
processing discussed above. In such embodiments, the threading
material is passed through sintering station 38A and binder removal
station 34A, and the leader is coupled to the green tape 20A on the
upstream or entrance side of binder removal station 34A.
[0355] Tension is then applied from the uptake reel 44A through the
leader to green tape 20A to begin the process of moving green tape
20A through binder removal station 34A and through sintering
station 38A. While a variety of approaches to threading green tape
through binder removal station 34A and through sintering station
38A may allow for sintering of green tape to be achieved (e.g.,
manual threading), Applicant has determined that the leader based
threading process discussed herein provides high quality/low warp
in the sintered tape material even at the leading edge of the
sintered material. This improved product quality decreases product
waste, improves process efficiency by eliminating the need for
handling/removal of warped sections on the green tape and improves
integrity of the wind of sintered material on uptake reel 44A due
to the shape consistency along the length of the sintered tape
material. In addition, in the context of hot threading (e.g.,
threading when binder removal station 34A and sintering station 38A
are at temperature), Applicant has found that use of the leader
based process discussed herein provides an efficient way to support
and pull the leading edge of the delicate, unbound portion of tape
material (e.g., unbound tape 36 shown in FIG. 3 and discussed
above) following exit from the binder removal station 34A until
sintering has occurred during traversal of the sintering station
38A.
[0356] In the embodiment shown in FIGS. 56 and 57, threading
material, shown as leader 1502A, is threaded from uptake reel 44A,
in the reverse direction through the channels of both sintering
station 38A and of binder removal station 34A such that a first
section, shown as end section 1504A, of the leader 1502A is
positioned outside of entrance opening 116A of binder removal
station 34A. In this arrangement, as shown in FIG. 56, leader 1502A
is a single contiguous piece of material positioned such that
leader 1502A extends the entire distance from uptake reel 44A and
all of the way through sintering station 38A and binder removal
station 34A.
[0357] Green tape 20A is moved from source reel 16A (e.g., via
unwinding of green tape 20A from the reel as discussed above)
toward entrance opening 116A of binder removal station 34A such
that a leading section 1506A of green tape 20A is located adjacent
to and overlapping end section 1504A of leader 1502A. As shown in
FIG. 57, after positioning leading section 1506A of green tape 20A
and end section 1504A of leader 1502A adjacent each other, leading
section 1506A of green tape 20A and end section 1504A are coupled
or bonded together upstream of binder removal station (e.g.,
between entrance opening 116A of binder removal station and source
reel 16A in the processing direction 14A). This forms a join or
bond between leader 1502A and green tape 20A at the overlapped
section.
[0358] Once leader 1502A is coupled to green tape 20A, a force is
applied to a portion of leader 1502A located outside of (e.g.,
downstream from) binder removal station 34A and sintering station
38A such that leader 1502A and green tape 20A are pulled in the
processing direction 14A through binder removal station 34A and
sintering furnace 38A. In the specific embodiment shown in FIG. 56,
a second or downstream end 1508A of leader 1502A is coupled to
uptake reel 44A, and the force generated by rotation of uptake reel
44A provides the force for moving/pulling leader 1502A and green
tape 20A through binder removal station 34A and sintering furnace
38A. In some embodiments, Applicant has found that processing
speeds of about 3 inches/minute (e.g., the speed that the tape
material is moved through system 1500A) are used during the thread
up process, and in specific embodiments, this speed may be
increased to about 6 inches/minute for sintering processing once
the join between leader 1502A and green tape 20A has traversed
binder removal station 34A and sintering furnace 38A.
[0359] Thus, through the use of leader 1502A, the downstream or
rewind side of system 1500A is initially coupled to the upstream or
unwind side of system 1500A, allowing for the initiation of reel to
reel sintering of the material of green tape 20A. In addition, by
providing this initial threading of binder removal station 34A and
sintering station 38A via connection between the same unwind and
uptake systems that advance green tape 20A during sintering
processing, the leader-based threading process discussed herein is
able to establish the proper tension and velocity for the entire
length of green tape 20A that traverses binder removal station 34A
and sintering station 38A, including the leading section 1506A of
green tape 20A at the overlapped location. Further, by providing a
horizontal pulling force through leader 1502A, the leader based
process discussed herein allows for threading through the
horizontally orientated channels of binder removal station 34A and
sintering station 38A, which can otherwise be difficult
(particularly given the delicate nature of the tape material
following binder removal).
[0360] As discussed above in detail regarding system 10, binder
removal station 34A is heated to remove or burn off binder from
green tape 20A, and sintering station 38A is heated to cause
sintering of the inorganic material of green tape 20A. In one
potential use of the threading process discussed herein, binder
removal station 34A and/or sintering station 38A are already at
their respective operating temperatures when leader 1502A is
threaded. This is the case when leader 1502A is used to thread
green tape 20A following a break in the material during reel to
reel sintering. In another potential use of the threading process
discussed herein, binder removal station 34A and/or sintering
station 38A are at a low temperature (e.g., below their respective
operating temperatures, off at room temperature, etc.) when leader
1502A is threaded through. This is the case when leader 1502A is
used to thread green tape 20A during initial start-up of system
1500A.
[0361] As discussed in more detail above, following the initial
movement of the join or overlap between leader 1502A and the
leading section 1506A of green tape 20A through binder removal
station 34A and sintering furnace 38A, green tape 20A is
continuously unwound from source 16A and moved through stations 34A
and 38A, forming the length of sintered material as discussed
above. Following sintering the sintered material is wound onto
uptake reel 44A. In one embodiment, leader 1502A is decoupled from
the sintered tape material once leading section 1506A of green tape
20A exits from sintering station 38A, and prior to winding of the
sintered tape material onto uptake reel 44A. In another embodiment,
leader 1502A is wound onto uptake reel 44A along with the sintered
tape material forming the innermost layers of the reel including
the sintered material.
[0362] In various embodiments, leader 1502A is an elongate and
flexible piece of material that is able to resist the high
temperatures of binder removal station 34A and sintering station
38A. In the coupling process shown in FIG. 57, leading section
1506A of green tape 20A overlaps end section 1504A of leader 1502A
forming overlap section 1512A. In this arrangement, a lower surface
of green tape 20A faces and contacts an upper surface of leader
1502A. In this arrangement, by positioning green tape 20A on top of
leader 1502A, leader 1502A acts to support leading section 1506A of
green tape 20A through binder removal station 34A and sintering
furnace 38A.
[0363] In some embodiments, an adhesive material 1510A is used to
form a bond joining leader 1502A to green tape 20A. As shown in
FIG. 57, in some such embodiments, adhesive material 1510A is
located on the upper surface of leader 1502A and forms a bond to
the lower surface of green tape 20A. As discussed in more detail
below, in various embodiments, Applicant has identified that the
matching of various characteristics, (e.g., coefficient of thermal
expansion (CTE) of the materials forming adhesive 1510A, leader
1502A and green tape 20A), facilitates maintenance of the bond
between leader 1502A and the tape material, particularly during
traversal of the high temperatures of sintering station 38A.
Further, a strong bond between leader 1502A and green tape 20A
allows for the desired level of tension to be applied to leader
1502A and transmitted through the bond provided by adhesive 1510A,
to green tape 20A. As discussed herein, Applicant has found that a
low (e.g., gram level), but consistent tension applied to the tape
material during sintering reduces warp that may otherwise be formed
across the width of the tape during sintering.
[0364] In various embodiments, Applicant has determined that the
volume of adhesive material 1510A used as well as the shape of the
applied adhesive material 1510A on leader 1502A influences the
properties of the bond formed between leader 1502A and green tape
20A. In specific embodiments, adhesive material 1510A is a small
volume (e.g., about 0.1 mL of an alumina-based adhesive material).
In one embodiment, adhesive 1510A is used to bond a leader 1502A to
an unsintered green tape material 20A, and in such embodiments,
Applicant has found that a round dot of adhesive 1510A works well.
Applicant hypothesizes that the round geometry helps to distribute
the thermal and mechanical stresses induced by cement and tape
shrinkage and CTE mismatch (if any) between the materials of leader
1502A, adhesive 1510A and green tape 20A. In another embodiment,
adhesive 1510A is being used to bond a leader 1502A to a tape of
partially sintered material, and in such embodiments, Applicant
believes that a line of adhesive 1510A extending across the width
of leader 1502A works well. Applicant hypothesizes that the line
geometry acts to apply an even constraint across the web as it
moves through the sintering station.
[0365] In specific embodiments, binder removal station 34A is
operated to remove liquid and/or organic components from adhesive
1510A (as well as from green tape 20A) as the overlapped section
1512A between leader 1502A and green tape 20A traverses binder
removal station 34A. Applicant believes that various properties of
the adhesive material 1510A and of green tape 20A relate to the
likelihood that the bond formed by adhesive material 1510A will
break during traversal of binder removal station 34A and sintering
station 38A. Applicant hypothesizes that the temperature profile
through binder removal station 34A can cause the organic material
in green tape 20A to soften and even melt prior to evolving from
the tape, which can help to limit the stress intensity around the
cement join as the individual components begin to change shape/size
due to shrinkage and thermal expansion. Applicant hypothesizes that
allowing green tape to `deform` or re-form around the location of
adhesive 1510A, prior to losing its elastic/plastic properties
helps to decrease defects and improves the quality of the bond
formed by adhesive 1510A. Similarly this elastic/plastic property
may also allow for venting of liquids and organic materials from
adhesive 1510A, which may otherwise cause an increase in pressure
between leader 1502A and green tape 20A. This increase in pressure
may cause the bond to fail or the gas build up may rupture through
green tape 20A.
[0366] In specific embodiments, the tension applied during the
process of pulling the overlapped section or join between leader
1502A and green tape 20A may be changed or increased as overlap
section 1512A traverses binder removal station 34A and/or sintering
station 38A. In a specific embodiment, a low level of tension,
e.g., of below 25 grams, is provided initially, during traversal of
overlap section 1512A across binder removal station 34A, and then
tension is increased as the overlap section 1512A traverses
sintering station 38A. In a specific embodiment, tension on the
order of 25 grams or more is applied once overlap section 1512A and
adhesive material 1510A reaches the center of sintering station
38A. Applicant believes that tension at this point can be increased
without separation of the bond between leader 1502A and green tape
20A because of the sintering of material of green tape 20A that has
occurred at this point. Applicant believes that applying a high
level of tension too early, before the strength has had a chance to
develop will generally lead to failure of the bond formed by
adhesive 1510A.
[0367] In various embodiments, coupling and/or support between
leader 1502A and green tape 20A is enhanced by various levels of
overlap between leader 1502A and green tape 20A. As can be seen in
FIG. 57, the greater the overlap between leader 1502A and green
tape 20A, the greater the amount of support provided by leader
1502A to green tape 20A. Similarly, the level of overlap between
leader 1502A and green tape 20A relates to the amount of
friction-based coupling between leader 1502A and green tape 20A,
which may supplement the bonding provided by adhesive 1510A. In
embodiments utilizing adhesive 1510A, Applicant has found that an
overlap section 1512A having a length measure in the processing
direction 14A of between one to five inches has performed well. In
some embodiments, coupling between leader 1502A and green tape 20A
may be provided by friction only (e.g., without adhesive 1510A) and
in such cases the length of the overlap section 1512A in the
processing direction 14A may be greater than five inches, such as
greater than 10 inches, between 10 inches and 30 inches, about 24
inches, etc.
[0368] In various embodiments, Applicant has identified a number of
material combinations for leader 1502A, green tape 20A, and
adhesive 1510A that provide the threading properties/functionality
discussed herein. In general, leader 1502A is formed from a
material that is different in at least one aspect from green tape
20A. In some such embodiments, leader 1502A is formed from the same
material type as the inorganic grains of green tape 20A but has a
different (e.g., higher) degree of sintering than the inorganic
material of green tape 20A. In some such embodiments, leader 1502A
is an elongate tape of sintered ceramic material, and green tape
20A supports unsintered or less sintered grains of the same type of
ceramic material.
[0369] In some other embodiments, leader 1502A is formed from an
inorganic material that is different from the material type of the
inorganic grains of green tape 20A. In a specific embodiment,
leader 1502A is formed from a ceramic material type that is
different than the ceramic material type of the inorganic grains of
green tape 20A. In some other embodiments, leader 1502A is formed a
metal material, while the inorganic grains of green tape 20A are a
ceramic inorganic material.
[0370] Applicant has found that the coupling arrangements shown in
FIG. 57 and described herein provides a level of coupling between
leader 1502A and green tape 20A that allows for good transmission
of force/tension from leader 1502A to green tape 20A without
significant risk of decoupling. Further, Applicant has found that
the risk of decoupling and warp caused during sintering can be
decreased by selecting materials for leader 1502A, adhesive 1510A
and the inorganic grain material of green tape 20A that have
relatively similar coefficients of thermal expansion (CTEs) as each
other. In various embodiments, the CTE of the material of leader
1502A is within plus or minus 50 percent of the CTE of the
inorganic material of green tape 20A, specifically within plus or
minus 40 percent of the CTE of the inorganic material of green tape
20A, and more specifically within plus or minus 35 percent of the
CTE of the inorganic material of green tape 20A. Similarly, in
various embodiments, the CTE of the material of leader 1502A is
within plus or minus 50 percent of the CTE of adhesive material
1510A, specifically within plus or minus 40 percent of the CTE of
adhesive material 1510A, and more specifically within plus or minus
35 percent of the CTE of adhesive material 1510A.
[0371] Leader 1502A can be formed from a variety of suitable
materials. In some embodiments, leader 1502A is formed from a
sintered ceramic material, and in other embodiments, leader 1502A
is formed from a metal material. In some embodiments, Applicant has
found that using a porous ceramic material for leader 1502A
increases the ability of adhesive material 1510A to bond to leader
1502A. Applicant believes that the porosity of leader 1502A allows
adhesive material 1510A to bond more easily than if the leader had
a less porous or polished surface. In specific embodiments, leader
1502A may be a platinum ribbon or a fully sintered ceramic
material, such as alumina or yttria stabilized zirconia (YSZ)
[0372] In specific embodiments, leader 1502A is sized to allow
handling and coupling to green tape 20A. In specific embodiments,
leader 1502A has a width that substantially matches (e.g., within
plus or minus 10%) of the width of green tape 20A. In specific
embodiments, leader 1502A has a thickness of between 5 .mu.m and
500 .mu.m and more specifically a thickness within the range of 20
to 40 .mu.m. Further, leader 1502A has a length sufficient to
extend from uptake reel 44A through both sintering station 38A and
binder removal station 34A and thus the length of leader 1502A
varies with the size of system 1500A.
[0373] While FIGS. 56 and 57 generally show leader 1502A as a long,
thin, flat section of sintered ceramic material, leader 1502A may
take other forms. For example, in one embodiment, leader 1502A may
be a ceramic board with a long length of platinum wire which is
cemented to the green tape. In another embodiment, leader 1502A may
be a length of ceramic fiber rope or ceramic fiber twine.
[0374] Adhesive material 1510A can be formed from a variety of
suitable materials. In some embodiments, adhesive material 1510A is
a ceramic adhesive material. In specific embodiments, adhesive
material 1510A is an alumina-based adhesive material, such as
alumina-based adhesive #C4002 available from Zircar Ceramics.
[0375] Referring to FIGS. 58-65, various systems and processes for
bending unbound tape 36B in the longitudinal or lengthwise
direction during sintering are shown and described. In general,
Applicant has determined that one of the unexpected challenges when
sintering wide, thin and continuous lengths of unbound tape 36B is
ensuring that the final sintered tape 40B has high levels of
cross-width flatness. A high level of cross-width flatness is
desirable when using the sintered tape material discussed herein in
a number of applications, such as substrates for thin-film
circuitry, thick film circuitry, solid-state lithium ion batteries
and the like.
[0376] Some continuous tape sintering processes may be susceptible
to certain flatness distortions (e.g., cross-width bowing, edge
wrinkle, bubble formation, etc.) believed to be formed due to
creation in-plane stresses within the tape material during
sintering. For example, Applicant has found that due to a variety
of factors, such as variations in ceramic particle density in
unbound tape 36B, large temperature differentials within the tape
material along the length of the systems (e.g., which may be in
excess of 1000 degrees C. due to the continuous nature of the
systems and processes discussed herein), processing speeds, etc.,
contribute to the generation of the in-plane stresses during
sintering, which in turn may induce buckling in the absence of a
countervailing application of force in a manner that allows for
release of these in-plane stresses.
[0377] For example, an alumina tape undergoing continuous sintering
via the systems discussed herein may have regions simultaneously at
room temperature and at the maximum sintering temperature. There
may also be regions of the tape beginning the sintering process
where shrinkage is minimal and areas of the tape where sintering is
nearly complete, where the shrinkage exceeds 8% or even 10% on a
linear basis. The gradient in shrinkage and temperature may be
sources of complex, biaxial stresses that may induce distortions,
such as by curling and wrinkling, even in a tape that enters the
sintering station having a level of flatness. Such distortions may
then become frozen into the sintered tape following cooling,
thereby degrading its potential uses.
[0378] As will be discussed in detail below, Applicant has
determined that stresses that may cause flatness distortions can
beat least in part counteracted by inducing a lengthwise or
longitudinal curve in the tape during sintering. During sintering,
the tape material plastically relaxes and deforms to the shape of
the induced lengthwise bend, which generates forces within the tape
material that tends to reduce in-plane stresses that may otherwise
occur, and a result may be to produce a sintered tape with a high
level of cross-width flatness. Applicant believes that by utilizing
lengthwise bending during sintering, a flatter sintered tape can be
produced despite variations in green tape particle density and high
production speed.
[0379] Further, in at least some embodiments, the flattening
process discussed herein produces flat, thin sintered articles
while avoiding/limiting surface contact and the resulting surface
defects and scratches common with contact/pressure-based flattening
devices, such as may be experienced when pressing a material
between cover plates during sintering. As will be shown below,
Applicant has developed a number of systems and processes for
inducing the longitudinal bend that leave at least one major
surface of the tape untouched during sintering, and some processes
that leave both upper and lower (major) surfaces of the tape
untouched during sintering. Applicant believes that other ceramic
sintering processes may not achieve the high levels of cross-width
flatness, in a continuous sintering process or with the limited
degree of surface contact provided by the system and processes
discussed herein.
[0380] Referring to FIG. 58, a process and system for producing a
high flatness, sintered continuous tape is shown. Specifically,
FIG. 58 shows a system 1600B for producing a sintered tape article,
according to an exemplary embodiment. In general, system 1600B is
generally the same as and functions the same as system 10 discussed
above, except that system 1600B includes a sintering station 38B
that includes a bending system 1602B located within sintering
station 38B. In general, bending system 1602B is configured or
arranged to induce a radius of curvature along a lengthwise or
longitudinal axis of unbound tape 36B while tape 36B is being
sintered at high temperatures (e.g., above 500 degrees C.) within
sintering station 38B. Applicant has determined that the inducement
of a longitudinal curve in the tape material via bending during
sintering may improve cross-width shape of the final sintered tape
40B via the mechanisms discussed herein.
[0381] In the specific embodiment shown in FIG. 58, bending system
1602B includes an upward facing convex curved surface 1604B that
defines at least a portion of the lower channel surface through
sintering station 38B. Upward facing convex curved surface 1604B
defines at least one radius of curvature, shown as R1B, and in
specific embodiments, R1B is or includes a radius of curvature
within the range of 0.01 m to 13,000 m. In general, as unbound tape
36B is moved through sintering station 38B, as discussed above,
gravity and/or the pulling tension in the tape causes tape to bend
into at least partial conformity with curved surface 1604B,
inducing a longitudinal bend into the tape during sintering at
elevated temperatures. In specific embodiments, the tension applied
to unbound tape 36B is at least 0.1 gram-force per linear inch of
width of unbound tape 36B, and unbound tape 36B is moved at a speed
of between 1 inch and 100 inches of tape length per minute through
sintering station 38B.
[0382] As shown in FIG. 58, curved surface 1604B is curved around
an axis that is parallel to the width axis of unbound tape 36B (and
is perpendicular to the plane of the view of FIG. 58). Thus, in
such embodiments, unbound tape 36B follows a path through sintering
station 38B generally defined by the channel 104B, and convex
curved surface 1604B defines a curved section of the path through
sintering station 38B. The bending is induced in unbound tape 36B
during sintering as it traverses the curved section of the path
defined by convex curved surface 1604B by being shaped into
conformity with curved surface 1604B.
[0383] In the specific embodiment shown in FIG. 58, curved surface
1604B forms a continuous curved surface, having a single radius of
curvature, that extends the entire length of channel 104B, between
the entrance and exit, of sintering station 38B. In such
embodiments, the radius of curvature of surface 1604B needed to
achieve both a sufficient level of bending and to fully extend the
length of sintering station 38B may vary based on the length of
sintering station. As such, for a given maximum rise, H1B, (shown
in FIG. 60) of curved surface 1604B, a short sintering station 38B
may have a smaller R1B than a longer sintering station 38B. As a
specific example, a sintering station 38B that is (at least) 1 m
long, may have a curved surface 1604B having an R1B between 1 m and
130 m. As a specific example, a sintering station 38B that is (at
least) 3 m long, may have a curved surface 1604B having an R1B
between 10 m and 1130 m. As a specific example, a sintering station
38B that is (at least) 6 m long, may have a curved surface 1604B
having an R1 between 40 m and 4500 m. As a specific example, a
sintering station 38B that is (at least) 10 m long, may have a
curved surface 1604B having an R1B between 120 m and 13,000 m. In
such embodiments, regardless of length, H1B may between 1 mm and 10
cm resulting in the R1B ranges shown above.
[0384] As discussed above regarding system 10, sintering station
38B is arranged such that a plane intersecting the entrance and the
exit of the sintering station forms an angle relative to a
horizontal plane that is less than 10 degrees. As discussed above,
this generally horizontal sintering arrangement allows unbound tape
36B to move through sintering station 38B in a generally horizontal
position. In such embodiments, curved surface 1604B defines the
lower surface of the path that tape 36B traverses between the
entrance and exit of sintering station 38B. Applicant believes that
by combining the horizontal sintering arrangement (discussed as
reducing air flow-based thermal gradients above) with the formation
of the longitudinal curved shape in the tape during sintering,
sintered tape with the high levels of flatness discussed herein can
be produced and/or may be produced at rapid speeds, far faster than
other sintering systems. It should be understood that while
Applicant believes that the bending during sintering in combination
with the horizontal sintering station 38B provides high levels of
flatness, in other embodiments, sintering station 38B may be
arranged at any angle from horizontal to vertical. In such
non-horizontal embodiments, the dimensions and positioning of
curved surface 1604B may be sufficient to achieve the desired level
of flatness.
[0385] As shown in FIG. 58, in the processing arrangement of system
1600B, a contiguous length of tape material, such as unbound tape
36B, is moved into a heating station, such as sintering station
38B. In this arrangement, a portion of the contiguous tape, shown
as unbound tape 36B, is located upstream from the entrance 106B
into sintering station 38B. Following sintering, a sintered portion
of the contiguous tape, such as sintered tape 40B, is located
downstream from an exit 108B of sintering station 38B. As will be
generally understood, at any one given point of time, the
contiguous tape includes a third portion of tape that is currently
being sintered within sintering station 38B. This third portion of
the contiguous tape is located between unbound, unsintered tape 36B
that is upstream from sintering station 38B and the sintered
portion 40B of the contiguous tape that is downstream from
sintering station 38B. The portion of the contiguous tape currently
being sintered, shown as tape portion 1606B, is located within
sintering station 38B as it is being heated to the desired
sintering temperature (e.g., a temperature greater than 500 degrees
C.).
[0386] In general, tape portion 1606B has a porosity that decreases
or degree of sintering that increases in the processing direction
(e.g., from right to left in the orientation of FIG. 58). As shown
in FIG. 58, tape portion 1606B is bent into conformity with upward
facing, convex curved surface 1604B such that tape portion 1606B
generally adopts a curved shape having a radius of curvature
matching R1B. As noted above, a longitudinally directed tension may
be applied to the contiguous tape such that tape portion 1606B is
bent into conformity with upward facing, convex curved surface
1604B.
[0387] As will generally be understood from the description of the
unwind and take-up portions of system 10 discussed above, system
1600B provides for continuous, reel-to-reel processing of a long
contiguous length of tape. In this manner, the entire contiguous
length of tape being processed may be moved continuously and
sequentially through sintering station 38B such that the entire
contiguous length of the tape being processed experiences bending
to the radius of curvature, R1B, of upward facing, convex curved
surface 1604B during traversal of sintering station 38B.
[0388] Referring to FIG. 59, details of sintering station 38B
including a bending system 1602B are shown according to an
exemplary embodiment. In the embodiment shown in FIG. 59, sintering
station channel 104B is defined, in part, by a tube 1608B (such as
an alumina tube as discussed above). In this embodiment, upward
facing, convex curved surface 1604B is defined by the upward facing
surface of a furniture or insert 1610B that is placed within tube
1608B. As shown in FIG. 59, the length of furniture 1610B is at
least 80%, specifically at least 90% and more specifically at least
95% of the length of channel 104B. In some embodiments, the length
of furniture 1610B is greater than the length of channel 104B such
that incoming and exiting sections of the tape are supported on the
upward facing, convex curved surface 1604B as it enters and exits
sintering station 38B.
[0389] As will generally be understood, in various embodiments, the
radius of curvature that defines continuous convex curved surface
1604B is a function of maximum rise, H1B, and the longitudinal
length, L2B, of surface 1604 (e.g., the distance in the horizontal
orientation of FIG. 60). In specific embodiments, where convex
curved surface 1604B extends the entire length of sintering station
38B, the longitudinal length of surface 1604B is substantially the
same as the longitudinal length of sintering station 38B. Thus, in
such embodiments, the radius of curvature of convex curved surface
1604B, R1B, is defined as R1B=H1B+(L2B{circumflex over ( )})/H1B,
and in various embodiments, 0.1 mm<H1B<100 mm, and 0.1
m<L2B<100 m. In other contemplated embodiments, only portion
of furniture 1610B forms a circular arc, and the surface may have
another geometry having a radius of curvature (among a more complex
geometry) or a maximum radius of curvature in ranges disclosed
herein for R1B of furniture 1610B.
[0390] In specific embodiments, insert 1610B is removable from
channel 104B and is removably coupled to or supported by tube
1608B. In such embodiments, this allows the different inserts 1610B
having differently curved surfaces 1604B to be placed into
sintering station 38B to provide a specific bend radius needed to
provide a desired level flattening for a particular process or tape
material type, thickness, rate of sintering, etc.
[0391] Referring to FIG. 60, in various embodiments, the lower
surface of channel 104B through sintering station 38B is defined by
upward facing, convex curved surface 1604B, and the upper surface
of channel 104B is defined by a downward facing, concave curved
surface 1612B. In specific embodiments, a or the radius of
curvature of downward facing, concave curved surface 1612B
generally matches (e.g., within 1%, within 10%, etc.) a or the
radius of curvature of upward facing, convex curved surface 1604B,
such as the corresponding radius of curvature vertically aligned
therewith. This curvature matchings ensures that the height channel
104B remains substantially constant along its length through
sintering station. In at least some designs, by having a constant
height and relatively low clearance relative to the tape being
sintered, vertical movement of air within channel 104B due to
thermal gradients can be reduced, which is believed to improve
shape and flatness of the final sintered tape.
[0392] In some embodiments, downward facing, concave curved surface
1612B is a surface of an insert 1614B. In such embodiments, insert
1614B is removably coupled to or supported by tube 1608B which
allows insert 1614B to be selected to match the curvature of the
lower furniture 1610B as may be used for a particular process or
material type.
[0393] Referring to FIG. 61, in various embodiments, the lower
surface of channel 104B through sintering station 38B is defined by
upward facing, convex curved surface 1604B that has more than one
curved section, shown as curved sections 1620, 1622 and 1624. Put
another way, curvature of the surface 1604B may include inflection
points, discontinuities, non-circular-arcing, etc. As shown in FIG.
61 for example, curved section 1620B has a first radius of
curvature, R1B', curved section 1622B has a second radius of
curvature, R2B, and curved section 1624B has a third radius of
curvature, R3B. In this embodiment, the path of the tape through
sintering station 38B is defined by R1B', R2B and R3B, and the tape
during sintering is bent to each of radiuses R1B', R2B and R3B
sequentially while being heated within sintering station 38B. In
various embodiments, R1B', R2B and R3B are or include a radius of
curvature between 0.01 m to 10 m. In specific embodiments, R1B',
R2B and/or R3B are different from each other.
[0394] Further, as shown in FIG. 61, in some embodiments, sintering
station 38B heats tape 36B traversing the different curved sections
1620B, 1622B and 1624B to different temperatures. In one specific
embodiment, the temperature to which tape 36 is heated is inversely
proportional to radius of curvature to which tape 36B is bent.
[0395] Referring to FIG. 62, in at least one embodiment, upward
facing convex curved surface 1604B is the upper surface of a gas
bearing 1630B. Gas bearing 1630B includes a gas supply channel
1632B which delivers pressurized gas (e.g., air, nitrogen, helium,
argon, etc.) to channel 104B (see FIG. 60). In this manner, the
pressurized gas supports tape 36B during traversal of sintering
station 38B which allows tape to be bent to the radius of curvature
of surface 1604B without requiring or with less contact with
surface 1604B.
[0396] Referring to FIGS. 63 and 64, in various embodiments,
bending system 1602B includes one or more mandrel or roller, the
outer surfaces of which define a convex curved surface around which
tape 36B is bent during sintering within sintering station 38B.
[0397] The flattening provided by bending tape 36B around a curved
structure, such as roller 1642B, is explained in more detail in
relation to FIG. 63. As shown in FIG. 63, a portion 1640B of tape
36B located upstream from roller 1642B may have a buckle or
flatness distortions shown as cross-width bow, represented by the
curved dotted-line 1644B. This defect may be caused by the complex
bi-axial stresses created within tape 36B during sintering, as
discussed above. As tape 36B is conveyed through sintering station
38B, it approaches roller 1642B with a radius of curvature,
.rho..sub.m. Tape 36B bends around roller 1642B and becomes flat in
shape. Tape 36B may have a lesser stiffness in the flat
configuration than it does when it has the cross-width bow 1644B.
The effect is a form of reverse-buckling or reduces changes of
buckling. In the bent state, tape 36B with cross-width bow 1644B
experiences a stress, .sigma..sub.d, on its surface in the
direction normal to that of conveyance that is directly
proportional to the curvature of cross-width bow 1644B,
.kappa..sub.d, such that:
.sigma..sub.d=E.kappa..sub.dt
where t is the thickness of the tape and E is its elastic modulus.
This technique helps reduce other flatness distortions such as edge
curl or bubble formation, with the result that local stress may be
proportionate to the local curvature. Thus, bending, such as around
roller 1642B or along surface 1604B discussed above, aids in
flattening across many defect types. As will be explained in more
detail below regarding FIG. 65, flattening via bending does not
require a surface against which the tape is pulled, and as such,
flattening may also be achieved via bending through a free-loop
configuration.
[0398] However, utilizing a curved surface such as the outer
surface of roller 1642B or surface 1604B, discussed above, is
advantageous in that it allows a tensile force to be applied
externally to the tape, by devices such as a weighted dancer 1680B
(FIG. 58). In such embodiments, the force, F (FIG. 63), pulls the
tape against the outer surface of roller 1642B or surface 1604B and
generates a second stress to aid in flattening the tape. The
stress, .sigma..sub.F, from the applied tensile force during
bending around a curved surface is defined by:
.sigma. F = 2 .times. F wt .times. sin .function. ( .theta. w 2 )
##EQU00001##
where w is the width of the tape and .theta..sub.w is the angle of
contact between as the curved surface (whether the outer surface of
roller 1642B or surface 1604B) and tape 36B, often referred to as
the wrap angle.
[0399] In various embodiments, roller 1642B can be fixed and unable
to rotate. In other embodiments, roller 1642B may rotate freely. In
yet other embodiments, the rate of rotation of roller 1642B may be
controlled to match the speed of conveyance of the tape or even to
drive or retard conveyance. In various embodiments, roller 1642B
may also be configured to move up or down normal to the tape to
change the wrap angle.
[0400] As shown in FIG. 64, in some embodiments, bending system
1602B may include multiple rollers against which tape 36B is pulled
during sintering to provide flattening. In the specific embodiment
shown in FIG. 64, bending system 1602B includes a pair of upper
rollers 1650B and a single lower roller 1652B. As tape 36B is
pulled through this roller arrangement, tape 36B is bent in the
longitudinal direction via contact with the outer surfaces of
rollers 1650B and 1652B. Similar arrangements of gas bearings may
be used, where one or more of the roller-to-tape interfaces shown
in FIG. 64 correspond to outward blowing surfaces of a respective
gas bearing, as shown in FIG. 62.
[0401] Referring to FIG. 65, in various embodiments, the curve or
bend-forming path that tape 36B traverses through sintering station
38B is formed via free loop segment 1660B. In this embodiment, a
section of tape 36B hangs under the influence of gravity to
generate the longitudinal bending as discussed herein. In such
embodiments, bending system 1602B includes one or more supports
1662B that are spaced apart from each other. The spacing of
supports 1662B defines a gap which allows tape 36B to hang downward
due to gravity between the supports to form free loop segment 1660B
having a radius of curvature, R1B'', as discussed above. In this
particular embodiment, the radius of curvature R1B'' formed via the
non-contact, free-loop segment 1660B may improve surface quality in
final sintered tape 40B as compared to the various contact-based
bending systems discussed herein. For example, utilizing free loop
segment 1660B eliminates or reduces scratches that may form in
contact-based systems. As another example, utilizing free loop
segment 1660B eliminates or reduces diffusion of chemical
constituents from surfaces which the sintering tape may come in
contact with in contact-based systems.
[0402] Applicant has performed tests that demonstrate that
longitudinal bending while sintering of various contiguous tape
materials decreases flatness distortions. Some results from these
tests are illustrated in FIG. 66. For example, as shown in FIG. 66,
40 .mu.m thick tapes of 3 mole percent yttria-doped zirconia (left)
and titanium oxide (right) were bent during sintering. The tapes
were cast onto a flat surface and were reformed to a curved shape
over the alumina rod. More specifically the tapes were draped
across a 9.5 mm diameter alumina rod and then heated at 100.degree.
C./hr to 1150.degree. C. The dwell time was five minutes. The
regions of tape bent across the alumina rod are locally flat from
one edge to the next (in the width direction). In contrast, regions
of the tape not supported by the curved surface of the rod were
free to respond to shrinkage mismatches and forming flatness
distortions. Specifically, wrinkles in the zirconia tape are
visible and emphasized with dotted black lines. The images also
evidence the plasticity of the tapes, where stresses over the rod
induce flattening.
[0403] Referring now to FIGS. 67A and 67B, an example of products
described above is shown. More specifically, a roll of
polycrystalline ceramic tape includes alumina with 1% by volume
yttria-stabilized zirconia with constituents ZrO.sub.2 and 3 mol %
Y.sub.2O.sub.3. The polycrystalline ceramic tape is 70 micrometers
thick, 36 millimeters wide, and over 8.5 m long. This tape was
sintered with the above-described processes using the
above-described equipment at a sintering temperature of
1650.degree. C. and at a rate of about 10 cm per minute along the
manufacturing line. The roll has a 3 to 6 inch diameter core. The
tape is flat or flattenable as discussed above.
[0404] FIG. 68 shows an example of a roll of polycrystalline
ceramic tape that is alumina with 300 parts per million magnesium
oxide. The tape in FIG. 68 is 77 microns thick, 36 mm wide, and
longer than 8 m. This tape was sintered with the above-described
processes using the above-described equipment at a sintering
temperature of 1650.degree. C. and at a rate of about 10 cm per
minute along the manufacturing line. The roll has a 3 to 6 inch
diameter core. The tape is flat or flattenable as discussed
above.
[0405] FIG. 69 shows an example of a roll of polycrystalline
ceramic tape that is yttria-stabilized zirconia (ZrO.sub.2 with 3
mol % Y.sub.2O.sub.3). The tape in FIG. 69 is 33 mm wide and about
a meter long. This tape was sintered with the above-described
processes using the above-described equipment at a sintering
temperature of 1575.degree. C. and at a rate of about 15 to 23 cm
per minute along the manufacturing line. The roll has a 3 to 6 inch
diameter core. The tape is flat or flattenable as discussed
above.
[0406] Accordingly, aspects of the present disclosure, as discussed
above, relate to a roll of flat or flattenable polycrystalline
ceramic or synthetic mineral tape of materials disclosed or
described herein, such as alumina tape as in FIGS. 67A and 67B,
that is at least partially sintered such that grains of the
polycrystalline ceramic or synthetic mineral are fused to one
another, the polycrystalline ceramic or synthetic mineral tape
comprising a thickness of no more than 500 micrometers, a width at
least 10 times greater than the thickness, and a length such that
the width is less than 1/10th the length, wherein the length of the
polycrystalline ceramic or synthetic mineral tape is at least 1
meter. In some such embodiments, the width of the polycrystalline
ceramic or synthetic mineral is at least 5 millimeters, and the
width of the polycrystalline ceramic or synthetic mineral tape is
less than 1/20th the length of the polycrystalline ceramic or
synthetic mineral tape, such as where the thickness of the
polycrystalline ceramic or synthetic mineral tape is at least 10
micrometers and/or where the thickness of the polycrystalline
ceramic or synthetic mineral tape is no greater than 250
micrometers, such as where the thickness of the polycrystalline
ceramic or synthetic mineral tape is no greater than 100
micrometers and/or where the thickness of the polycrystalline
ceramic or synthetic mineral tape is no greater than 50
micrometers. In some such embodiments, the polycrystalline ceramic
or synthetic mineral tape has fewer than 10 pin holes of a
cross-sectional area of at least a square micrometer passing
through the polycrystalline ceramic or synthetic mineral tape, per
square millimeter of surface on average over a full surface of the
polycrystalline ceramic or synthetic mineral tape. In some such
embodiments, the polycrystalline ceramic or synthetic mineral tape
has fewer than 1 pin hole of a cross-sectional area of at least a
square micrometer passing through the polycrystalline ceramic or
synthetic mineral tape, per square millimeter of surface on average
over a full surface of the polycrystalline ceramic or synthetic
mineral tape. In some such embodiments, the length of the
polycrystalline ceramic or synthetic mineral tape is at least 10
meters, the width of the polycrystalline ceramic or synthetic
mineral tape is at least 10 millimeters, such as where the width of
the polycrystalline ceramic or synthetic mineral tape is no greater
than 20 centimeters and/or where the polycrystalline ceramic or
synthetic mineral tape has high surface quality such that first and
second surfaces of the polycrystalline ceramic or synthetic mineral
tape both have at least a square centimeter of area having fewer
than ten surface defects from adhesion or abrasion with a dimension
greater than five micrometers, the high surface quality
facilitating strength of the sintered article. In some such
embodiments, the polycrystalline ceramic or synthetic mineral tape
supports greater than 1 kilogram of weight without failure, and/or
the polycrystalline ceramic or synthetic mineral tape supports
about 20 megapascals of tension without failure, such as where the
width of the polycrystalline ceramic or synthetic mineral tape is
at least 50 millimeters. In some such embodiments, the
polycrystalline ceramic or synthetic mineral tape has total
transmittance of at least 30% at wavelengths from about 300 nm to
about 800 nm and/or the polycrystalline ceramic or synthetic
mineral tape has diffuse transmission through the polycrystalline
ceramic or synthetic mineral tape of at least about 10% up to about
60% at wavelengths from about 300 nm to about 800 nm, and/or the
polycrystalline ceramic or synthetic mineral tape is translucent
such that text in contact with the polycrystalline ceramic or
synthetic mineral tape may be read through the polycrystalline
ceramic or synthetic mineral tape. In some embodiments the roll is
further comprising a mandrel or spool, where the polycrystalline
ceramic or synthetic mineral tape bends around the mandrel or spool
at a diameter of 1 meter or less such as where the polycrystalline
ceramic or synthetic mineral tape is wound on the spool, such as
where the spool has a diameter of at least 0.5 centimeters and no
greater than 1 meter. In some such embodiments, the polycrystalline
ceramic or synthetic mineral tape is fully sintered and dense,
having a porosity of less than 1%, such as where the
polycrystalline ceramic or synthetic mineral tape has a porosity of
less than 0.5%. In some such embodiments, the polycrystalline
ceramic or synthetic mineral tape is substantially unpolished such
that surfaces of the polycrystalline ceramic or synthetic mineral
tape have a granular profile, such as where the granular profile
includes grains with a height in a range from twenty-five
nanometers to one-hundred-and-fifty micrometers relative to
recessed portions of the surfaces at boundaries between the
respective grains and/or the granular profile includes grains with
a height in a range from twenty-five nanometers to one-hundred
micrometers relative to recessed portions of the surfaces at
boundaries between the respective grains and/or the granular
profile includes grains with a height of at least fifty nanometers
relative to recessed portions of the surfaces at boundaries between
the respective grains and/or the granular profile includes grains
with a height of no more than eighty micrometers relative to
recessed portions of the surfaces at boundaries between the
respective grains. In some such embodiments, while being
substantially unpolished, at least one surface of the In some such
embodiments, the tape has a roughness in a range of one nanometer
to ten micrometers over a distance of one centimeter in a
lengthwise direction along the surface.
[0407] According to an exemplary embodiment, an article (e.g., tape
of sintered ceramic, as disclosed herein), has a thickness of less
than 50 micrometer or other thicknesses as disclosed herein, and
fewer than 10 pin holes (i.e., passage or opening through body from
first to second major surface having a cross-sectional area of at
least a square micrometer and/or no larger than a square
millimeter), per square millimeter of surface on average over the
full surface (or fewer than 10 pin holes over the full surface, if
the surface area is less than a square millimeter; or alternatively
on average over a long length of the article, such as over 1 meter,
over 5 meters), such as fewer than 5 pin holes, fewer than 2 pin
holes, and even fewer than fewer than 1 pin hole per square
millimeter of surface on average over the full surface or long
length. Pin holes are distinguished from vias, which are purposely
cut, typically in pattern of a repeating geometry (e.g., circular,
rectilinear) to be filled with conductive material for example, or
perforations formed in a pattern of a repeating geometry, which may
help as fiducial marks with alignment in roll-to-roll processing
for example.
[0408] FIG. 70 compares sintering schedules for sintering of
ceramics (e.g., alumina) using the processes disclosed herein,
compared to traditional batch firing in a kiln using setters, and
stacked green ceramic plates. The total time for processing at
sintering temperatures, including multiple passes (e.g., 2, 3, 4
passes) through the furnace system disclosed above, may be less
than one hour. Conventional sintering may take 20 hours. Applicants
have discovered measurable, identifiable differences between the
"fast" sintering of the present disclosure versus traditional, such
as with respect to the microstructure of ceramics manufactured
according to the present technology. More specifically, Applicants
have found that fast firing of thin, unstacked tapes, as disclosed
above, results in less melding or combining of individual particles
or grains into one another. The resulting sintered grain size of
the present technology is substantially smaller and closer to the
original green state grain size or particle size. Whereas
traditional sintering may result in sintered grains that are ten
times the original particle sizes, grains of polycrystalline
ceramics manufactured with the fast sintering schedule disclosed
herein may have sintered grain sizes that are less than five times
the original green state grain or particle sizes, such as less than
three times on average. Furthermore, and surprisingly, articles
manufactured according to the present technology also may have
correspondingly high density, such as at least 90% relative
density, at least 95% relative density, at least 98% relative
density, and this high relative density is achieved with the
relatively small grain size, as just described, which may be less
than 10 micrometers mean particle size, such as less than 5
micrometers, such as less than 3 micrometers, depending upon the
starting particles sizes and composition, such as for alumina,
cubic zirconia, ferrites, barium titanate, magnesium titanate, and
other inorganic materials that may be processed into tapes, sheets,
etc. using the technology as disclosed herein.
[0409] Some embodiments may use multiple passes through a furnace
for sintering the same article (e.g., tape), such as a first pass
("bisque pass") to increase strength of the tape after organic
binder is removed, as second pass to partially sinter the tape, a
third pass to further sinter the tape, and a forth pass to sinter
to final density. Use of multiple passes or a series of furnaces or
hot zones may help to control stresses in the tape due to shrinkage
of the tape material during sintering. For example, some furnaces
for sintering may be 12 to 14 inches long, while others may be 40
to 45 inches long, others over 60 inches, and still others of other
lengths. For shorter furnaces, multiple passes or arrangements of
multiple furnaces in series may be particularly helpful for
sintering inorganic materials with greater degrees of shrinkage.
Also, longer furnaces or arrangements of furnaces in series may
also allow for faster rates of green tape movement, by increasing
soak times (i.e. exposure to sintering conditions) at such faster
rates.
[0410] After analyzing samples sintered at a high speed (e.g., rate
of 4 inches per minute) with a sintering temperature (e.g.,
1650.degree. C.), that are particularly thin, as described herein
(e.g., a thickness of 20 to 77 micrometers), alumina or other
materials disclosed herein made with the presently disclosed
technology may have the following attributes: material purity of at
least 90% by volume, such as at least 95%, such as at least 99%,
where high purity may result from the narrow passage and control of
air flow as well as the time of sintering, efficiency of the binder
removal, and starting constituents, among other factors described
herein; surface roughness measured by AFM in units of nanometers of
less than 100, such as less than 60, such as about 40 for shiny
face and/or less than 150, such as less than 100, such as about 60
for mat face, when measured at a 30 mm scan, where the mat face is
rougher than the shiny face due to interface with a floor of the
sintering furnace; grain size of about 1 mm in cross-section, or
other grain sizes as disclosed herein; porosity of less than 10% by
volume for a sintered article, such as less than 5%, such as less
than 3%, such as less than 1%, such as less than even 0.5%, which
may in part be due to the fast firing process, which maintains
small grain/particles sizes as disclosed above, whereby gas may be
less likely to be trapped within grains, as may be a characteristic
limitation for traditional batch sintering and longer firing
processes (limiting phenomenon known as `pore/boundary separation`
which may be overcome by sintering processes as disclosed herein).
Alumina tape manufactured according to technology disclosed herein
has a specific heat capacity of at least and/or no more than about
0.8 J/gK at 20.degree. C. and 1.0 J/gK at 100.degree. C. as
measured via ASTM E1269 standard test protocol/method; hardness at
room temperature (23.degree. C.) measured via nano-indentation of
at least and/or no more than about 23.5 GPa, such as on at least
and/or no more than about a 40 .mu.m thick alumina tape, and/or
other tape or sheet sizes disclosed herein; two-point bending
strength of at least and/or no more than about 630 MPa, such as at
least in part due to control of voids and smaller grain size;
elastic modulus of at least and/or no more than about 394 GPa as
measured via dynamic mechanical analysis (DMA) for 3 point bend;
coefficient of thermal expansion of at least and/or no more than
about 6.7 ppm/.degree. C. average over the range of 25-300.degree.
C., at least and/or no more than about 7.6 ppm/.degree. C. average
over the range of 25-600.degree. C., at least and/or no more than
about 8.0 ppm/.degree. C. average over the range of 25-300.degree.
C.; dielectric strength of at least about 124.4 kV/mm at
250.degree. C. as per ASTM D149 standard test protocol/method, such
as on at least and/or no more than about a 40 .mu.m thick alumina
tape; dielectric constant (Dk) of at least and/or no more than
about 9.4 at 5 GHz and of at least and/or no more than about 9.3 at
10 GHz as per ASTM D2520 standard test protocol/method; dielectric
loss/loss tangent of at least and/or no more than about
8.times.10.sup.-5 at 5 GHz and of at least and/or no more than
about 1.times.10.sup.-4 at 10 GHz as per ASTM standard test
protocol/method (D2520); volume resistivity of at least and/or no
more than about 3.times.10.sup.15 ohm-centimeter at 25 as per D257,
at least and/or no more than about 4.times.10.sup.14 ohm-centimeter
at 300 as per D1829, and/or at least and/or no more than about
1.times.10.sup.13 ohm-centimeter at 500 as per D1829; transmittance
of at least about 50%, such as at least about 60%, such as at least
about 70% for one, most, and/or all wavelengths between about
400-700 nanometers, such as on at least and/or no more than about a
40 .mu.m thick alumina tape, and/or other tape or sheet sizes
disclosed herein; transmittance of at least about 50%, such as at
least about 65%, such as at least about 80% for one, most, and/or
all wavelengths between about 2-7 micrometers and/or between about
2-7 millimeters, such as on at least and/or no more than about a 40
.mu.m thick alumina tape, and/or other tape or sheet sizes
disclosed herein; and less than 100 ppm outgassing as measured via
GC-MS at 200.degree. C., such as less than 50 ppm, such as less
than 10 ppm.
[0411] Referring now to FIGS. 71A and 71B, two samples of alumina
as shown side-by-side to demonstrate impact of sintering time and
temperature. The alumina of FIG. 71A was processed through above
disclosed manufacturing system at a rate of 4 inches per minute,
having a 4 minute hot "soak" or exposure to 1650.degree. C.
sintering temperature, while the alumina of FIG. 71B was
manufactured at 8 inches per minute, having a 2 minute soak at
1600.degree. C. As can be seen, the grain size greatly increases as
sintering time increases, however porosity is low in both figures,
such as below 5% by volume. FIGS. 72A and 72B show cross-sectional
digital images of ceramic tape made via corresponding processes:
FIG. 72A at 8 inches per minute at 1650.degree. C. and FIG. 72B at
4 inches per minute at 1600.degree. C.
[0412] FIGS. 73A, 73B, and 73C show increasing magnification of
grain boundaries of alumina manufacturing according to the present
technology. Of interest is that the grain boundaries of articles
manufactured according to the present technology are particularly
pristine. As shown in FIG. 73C, the molecular arrays of the
adjoining crystal grains (crystal lattices) essentially directly
contact one another, such that there is less than 5 nm of
intermediate amorphous material, such as less than 3 nm of
intermediate amorphous material, such as less than 1 nm of
intermediate amorphous material. Applicants believe that the
crystal grain interface may be, at least in part, attributed to the
fast sintering, gas flow control, and binder burn-off technology
disclosed herein. FIGS. 74 and 75 show other grain boundaries of
articles of polycrystalline ceramic or synthetic mineral according
to the present technology. Applicants believe hermeticity and/or
strength of such articles may be particularly advantageous relative
to ceramics having some or more amorphous material between grains.
The images of FIGS. 73-75 were gathered via transmission electron
microscope.
[0413] FIGS. 76 and 77 show similar microstructure for different
materials. FIG. 76 corresponds to alumina with 1% by volume
yttria-stabilized zirconia (ZrO.sub.2 with 3 mol % Y.sub.2O.sub.3)
processed at 4 inches per minute and at 1650.degree. C. Similarly,
FIG. 77 shows a polished cross-section of alumina with 10% by
volume titanium oxide (TiO.sub.2) processed at 4 inches per minute
and at 1550.degree. C.
[0414] FIG. 78 is a digital image of a ribbon of high purity fused
silica manufactured from loose silica particles bound in green tape
as disclosed herein. The silica particles are inorganic, but may
not be crystalline or a synthetic mineral. Accordingly, Applicants
have found that the technology disclosed herein may be used to
manufacture tapes, with geometries as disclosed herein for
polycrystalline ceramic and synthetic mineral, but comprising,
consisting essentially of, or consisting of inorganic material that
may be amorphous, such as glass that is difficult to manufacture
via float or fusion forming processes, such as silica or other
glasses having a high melting temperature and/or high viscosity,
such as a glass transition temperature of at least 1000.degree.
C.
[0415] FIGS. 79A and 79B show the polished cross-section of
sintered tape of silica having a granular profile. The tape of 79A
and 79B was manufactured at a sintering temperature of 1150.degree.
C. Individual particle so silica have been fused together to form
the tape. As shown in FIG. 79B, the particles are generally
spherical and have a cross-section of less than a micrometer. By
contrast, FIG. 80 shows silica tape manufactured according to the
technology disclosed herein, as sintered at 1250.degree. C. The
granular profile is still present, but is muted relative to the
silica of FIG. 79B. FIG. 81 shows fully dense and amorphous silica
that has been sintered according to the present disclosure at
1300.degree. C. Applicants contemplate that silica tape with a
granular profile may be useful for scattering of light or other
applications. Accordingly, FIGS. 79 to 81 demonstrate that
compositions disclosed herein may be in the form of an amorphous
article, such as a tape, if processed at a high enough temperature.
With that said, Applicants have found that if the tape is heated
too much, the tape may become difficult to handle and/or may lose
shape.
[0416] Referring now to FIG. 82, rapid thermal processing and
continuous sintering, such as of inorganic tape, may be used to
produce lithium-containing materials, as discussed above, such as
for use as a thin cathode structure in lithium batteries. For
example, Applicants believe lithium-containing materials, such as
lithium manganate spinel (LiMn.sub.2O.sub.4), LiCoO.sub.2 or
LiFePO.sub.4, are good candidates cathode structure. Unexpectedly,
Applicants have found that the presently disclosed technology
mitigates lithium loss due to high vapor pressure and/or mitigates
change in reduction in valence of the transition metal oxide and
release of oxygen on heating. For example, FIG. 82 shows powder
x-ray diffraction traces for similar 30 .mu.m thick tapes
containing LiMn.sub.2O.sub.4 powder (commercially available from
Novarials, Sigma Aldrich, Gelon, Mtixtl, and/or others) that was
rapidly sintered at 1250.degree. C. for 6 minutes using the
presently disclosed technology and LiMn.sub.2O.sub.4 powder
conventionally sintered at 1250.degree. C. for 4 hours. As shown in
FIG. 82, the rapidly sintered material is still single phase spinel
with peak intensities and positions of LiMn.sub.2O.sub.4. The
lithium is retained and so is the average valence of 3.5 for the
manganese ions. Accordingly, such lithium-containing articles
(e.g., tapes, sheets) sintered by the presently disclosed
technology may meet minimum chemical and phase requirements for a
cathode supported battery. In contrast, the conventionally sintered
tape is mostly Mn.sub.3O.sub.4 with lesser amount of
LiMn.sub.2O.sub.4 remaining, as shown in FIG. 82. There was
extensive loss of lithium and a drop in average manganese valence
to 2.67.
[0417] Applicants have also found that the presently disclosed
sintering system may be advantageous for pore removal during
sintering, such as when rapidly sintering lithium-containing
inorganic materials, such as LiMn.sub.2O.sub.4, and/or other
materials susceptible to vaporization of volatile constituents.
With conventional sintering techniques, grain growth may limit pore
removal, such as by trapping pores within larger grains.
[0418] For comparison purposes, Applicants manufactured a pill of
die-formed LiMn.sub.2O.sub.4 sintered at 1300.degree. C. The mean
particle diameter of the powder used to make the pill was 0.5
.mu.m; to enhance surface tension and favor pore removal. Loss of
lithium and change of Mn-valence were controlled or slowed in three
ways. First, the size of the pill was large, greater than 25 mm in
diameter and 5 mm in thickness to provide surplus material. Second,
the sintering was performed under a cover. Third, the pill was
supported on platinum. Powder x-ray diffraction confirmed the
resulting pill is single phase lithium manganite spinel and
chemical analysis shows negligible lithium loss relative to the
as-received material and that the average valence of Mn is 3.5. The
average grain size of the sintered pill is about 40 .mu.m and there
is more than 15% of porosity.
[0419] Returning to the presently disclosed technology, porosity in
sintered materials may be limited or particularly low, and grains
may be particularly small, which may be beneficial in applications,
such as cathode support. By contrast, excess porosity and large
grains may be detrimental to strength of most ceramics. Further,
Applicants have found that rapid thermal sintering, using
techniques and equipment disclosed herein, favors pore removal over
grain growth. Referring to FIGS. 83 and 84, as-fired surfaces of
rapidly sintered LiMn.sub.2O.sub.4 tape (FIG. 83, sintered at
1250.degree. C. for 6 min; and FIG. 84 sintered at 1350.degree. C.
for 3 min). The initial mean particle diameter was 0.5 .mu.m, like
the above pill example. The amount of porosity is much lower than
in the example of the conventionally sintered pill. More
specifically, the porosity appears closed and in an amount less
than 5%. The grains are also smaller than the above pill example.
More specifically, the grains are about 10 .mu.m and 25 .mu.m,
respectively in FIGS. 83 and 84. Put another way, porosity of
lithium-containing sintered material (e.g., lithium manganite) was
less than 15%, such as less than 10%, such as less than 7%, such as
less than about 5% and/or the grains were less than 40 .mu.m, such
as less than 30 .mu.m. Also different than conventional sintering
of lithium-containing materials, the present technology uses thin
sheets or tapes as disclosed herein, as opposed to large volume
pills or boules, which facilitates the rapid sintering; controlling
loss of volatile constituents by reducing the time of sintering,
with or without control of surrounding vapor pressures. Applicants
contemplate that the presently disclosed sintering system,
including the rapid thermal sintering, may also facilitate
sintering at an even lower temperature and/or sintering on an
alumina or other low-cost support in a continuous process as
disclosed herein.
[0420] LiCO.sub.2 and LiFePO.sub.4 are other examples of
lithium-containing inorganic materials that may be sintered using
the presently disclosed technology, and may be useful as cathode
material or for other applications. More generally, sintering of
other transition metal oxides with minimal loss of oxygen is
possible is possible using the presently disclosed technology.
[0421] Referring now to FIGS. 85A and 85B, the cross-section of a
green tape is shown under two different levels of magnification.
More specifically, a slip for the green tape was made of about
47.35 wt % of a garnet powder with the composition
Li.sub.6.5La.sub.3Zr.sub.1.5Ta.sub.0.5O.sub.12, 6.45 wt % lithium
carbonate, 31.74 wt % n-propyl propionate, 1.30 wt % glyceryl
Trioleate, 3.56 wt % n-butyl stearate, and 9.60 wt % Lucite
International Elvacite 2046, a high molecular weight
iso-butyl/n-butyl methacrylate co-polymer. The slip mixture was
vibratory milled for 18 hours. The slip was cast on a Teflon
carrier film with a 10 mil blade and dried overnight. The resulting
dried tape was about 85 to 90 .mu.m thick with particles averaging
0.6 .mu.m. The green tape has been released from the carrier film
in FIGS. 85A and 85B.
[0422] In this example, the binder was subsequently burned off of
the green tape of FIGS. 85A and 85B at 400.degree. C., where
environment for the burn-off was controlled to be argon gas and
time for the binder burn-off was 30 minutes. Next the tape with
burned-out/charred binder was fired in a continuous sintering
furnace as disclosed herein at 1200.degree. C. for 15 minutes in
air. The fired tape was at least and/or no more than about 50 to 55
.mu.m thick with grain sizes averaging at least and/or no more than
about 2 to 3 .mu.m, as shown in FIGS. 86A and 86B. The resulting
tape had conductivities at least and/or no more than about
3.7.times.10.sup.-4 to 3.8.times.10.sup.-4 S/cm, where S is
siemens. The fired samples were at least and/or no more than about
96 to 98 wt % cubic garnet phase.
[0423] Using the presently disclosed technology, some embodiments
include use of high-lithium content for forming particularly dense
garnet tape or other articles. Applicants have found that excess
lithium (excess in terms of more than the lithium according to
stoichiometry of the sintered article, such as at least 1 vol %
excess, at least 10 vol % excess, at least 20 vol % excess, at
least 50% vol %, and/or no more than 100 vol % more than the
stoichiometric amount in the sintered article) in the green tape
may promote dense garnet tape sintering and/or compensate for loss
of lithium during the sintering. Such high-lithium content powder
for use in the green tape may be made by batching with excess
amounts of lithium precursor in the raw material in garnet powder
preparation and/or by making stoichiometric or slightly excess (no
more than 50 vol % excess relative to final article stoichiometry)
lithium garnet powder and then adding in more lithium precursor
during slip preparation for tape casting. Some advantages of the
latter approach include that the lower lithium-containing batch may
be easier to prepare because high lithium content may be
hygroscopic and difficult to mill and/or the amount of excess
lithium may be easily adjusted to compensate for different
processing conditions. Examples of lithium precursors for adding
such excess lithium during the slip preparation include
Li.sub.2CO.sub.3, LiOH, LiNO.sub.3, LiCl, etc. Methods of adding
excess lithium as just described include having lithium precursor
pre-react with the garnet powder, such as by heating the lithium
precursor and garnet powder mixture to about 900 to 950.degree. C.
for about 1 to 5 hours. Alternatively, without pre-reaction, the
excess lithium may be added as a fine precursor powder and/or by
providing enough milling to decrease the particle size to prevent
leaving pores in the ceramic, such as precursor powder particle
size of less than 3 micrometers, such as less than 1 micrometer.
Applicants have found that the amount of excess lithium is enough
for sintering via the above-described technology, but not too much
so as to leave excess lithium in the sintered article or to cause
tetragonal phase formation. Accordingly, at least and/or no more
than about 5.8 to 9 mol total lithium per mol of garnet, for garnet
that sinters at at least and/or no more than about 1000.degree. C.
in at least and/or no more than about 3 minutes (e.g., low
lithium-content garnet); at least and/or no more than about 7 to 9
mol total lithium per mol of garnet, for garnet that sinters at at
least and/or no more than about 1150.degree. C. in at least and/or
no more than about 3 minutes. With that said, for garnet,
especially high lithium-content garnet, that may be highly reactive
to organics used in tape casting slip, to stabilize the garnet, the
powder may be treated beforehand using an acid treatment, such as
peracetic acid (peroxyacetic acid, PAA), citric acid, stearic acid,
hydrochloric acid, acetic acid; a solvent, such as a non-water
containing solvent, such as isopropyl alcohol, PA, PP, etc.; with a
treatment of soaking the garnet powder, which may be excess lithium
precursor pre-reacted garnet powder as disclosed above, in 1 to 5
wt % acid/solvent solution for 2 hours, with solid loading of about
50%, then drying the solvent, where the obtained/treated powder may
be used for making tape casting slip. Alternatively, low
lithium-content garnet powder plus inert lithium precursor, such as
Li.sub.2CO.sub.3, may be used in making a casting slip
directly.
[0424] At least one embodiment of acid treatment includes ball
milling for 3 hours and oven drying at 60.degree. C. 100 grams of
MAA (Li.sub.5.39La.sub.3Zr.sub.1.7W.sub.0.3Ga.sub.0.5O.sub.x,
lithium garnet or cubic LLZO (e.g.,
Li.sub.7La.sub.3Zr.sub.2O.sub.12), low lithium-content garnet
powder) plus 10.7 grams Li.sub.2CO.sub.3, 2.2 grams of citric acid,
and 100 grams of isopropyl alcohol. At least one embodiment of tape
casting slip manufacturing includes attrition milling for 2 hours
100 grams of acid treated MAA plus 10.7 wt % Li.sub.2CO.sub.3,
84.67 grams methoxy propyl acetate solvent, 12.14 grams PVB Butvar
B-79 binder, and 2.4 grams dibutyl phthalate plasticizer. Another
embodiment of tape casting slip manufacturing includes attrition
milling for 2 hours 100 grams of acid treated MAA plus 8.4 wt %
Li.sub.2CO.sub.3 that has been pre-reacted in turbular mix for 30
minutes and calcine at 900.degree. C. for 1 hour, 66.67 grams
ethanol and 33.33 grams butanol solvent, 12 grams PVB Butvar B-79
binder, and 10 grams dibutyl phthalate plasticizer. Another
embodiment of tape casting slip manufacturing includes 100 grams of
GP (Li.sub.6.1La.sub.3Zr.sub.2Al.sub.0.3 O.sub.12, lithium garnet
or cubic LLZO) plus 8.4 wt % Li.sub.2CO.sub.3 that has been
pre-reacted (e.g., mixed for 30 minutes and heated to 900.degree.
C. for 1 hour), 66.67 grams ethanol and 33.33 grams butanol
solvent, 12 grams PVB Butvar B-79 binder, and 10 grams dibutyl
phthalate plasticizer. Applicants have found that low lithium
content garnet with Li.sub.2CO.sub.3 for excess lithium precursor,
as described above, may not require acid treatment; for example,
attrition milling for 2 hours 100 grams of MAA with 10.7%
Li.sub.2CO.sub.3, 84.67 grams methoxy propyl acetate solvent, 2.08
grams fish oil (Z1) dispersant, 12.14 grams of PVB Butvar B-79
binder, and 2.4 grams of dibutyl phthalate plasticizer.
Alternatively, acid based dispersant may be added into the slip,
such as with up-milling for two hours 100 grams MAA with 10.7%
Li.sub.2CO.sub.3, 104 grams EtOH and BuOH in a 2:1 ratio solvent, 1
gram of citric acid as dispersant, 16 grams PVB B-79 as binder, and
14 grams of dibutyl phthalate as plasticizer.
[0425] Aspects of the present technology relate to sintering of
higher viscosity, higher processing temperature glasses, such as
fused silica or ultra-low-expansion (amorphous) glass compositions
that may be difficult or impossible to manufacture as rolls of high
viscosity glass tape and/or cut into sheets via other methods, such
as fusion drawing, float glass, or other ordinary glass tank
melters. Accordingly, inorganic material with geometries (e.g.,
thicknesses, rolled format, lengths, widths) and attributes (e.g.,
flatness, low warpage) disclosed herein include higher viscosity,
higher processing temperature glasses manufactured with the present
technology. Additional benefits of the present technology include
compositional homogeneity at small (sub-millimeter) length scale
and large length scale (millimeter to multi-centimeter variations)
via use of controlled air flow during sintering, tension control of
the tape, and mixed powders in a slurry as opposed to flame
deposition techniques, which may lead to compositional variations
at different scales. Additionally, the rolls or sheets of higher
viscosity, higher processing temperature glasses may be annealed.
Applicants have found that the presently disclosed technology,
including furnace with heat zones, not only allows sintering but
also an ability to continuously anneal the glass tape as it is
being formed and/or via a set of one or more lower temperature
furnaces. A corresponding low and uniform stress field in annealed
glass facilitates uniform dimensional changes during post-firing
leading to less warpage in thin, post-treated annealed sheets
compared to unannealed articles. Further, technology disclosed
herein, including lower temperature processing (compared to flame
deposition with temperatures typically greater than 2100.degree.
C.) and rapid sintering (compared to batch sintering), also
facilitates incorporation of volatile dopants such as boron and
phosphorous at levels greater than 0.5 wt % of such inorganic
material (e.g., viscous, high temperature amorphous glasses), which
may be difficult or impossible to add via flame deposited
materials. With that said, equipment disclosed herein may be used
to heat green or partially sintered materials to a higher
temperature than would typically be used in a conventional
sintering process, where the short time at soak limits grain growth
and accelerates pore removal.
[0426] Applicants have found a high level of compositional
homogeneity with viscous, high temperature amorphous glass
articles, when green tape is made with glass powder mixed in slurry
form, such as in the solgel, extrusion, or casting processes and
sintering is performed as described above. More specifically,
Applicants have found hydroxide (OH), deuterium (OD), chlorine (Cl)
and fluorine (F) variations less than +/-2.5 ppm at spatial
variations of 1 mm and less than +/-5 ppm within distances 3 cm,
such as with variations less than +/-1 ppm at frequencies less than
1 mm and less than +/-3 ppm at frequencies less than 3 cm. In some
embodiments, compositional homogeneity is with chemical variations
of titania of less than +/-0.2 wt %, such as less than +/-0.1 wt %
at distances of 1 mm in titania containing glass, and less than 10
wt % at distances of 1 mm variations in Germania levels in Germania
containing glass. In some embodiments, index variations less than
10 ppm, such as less than 5 ppm as measured via XRF techniques (wt
% metals) when mixed component glasses are used.
[0427] Referring now to FIG. 87, examples of viscous, high
temperature amorphous glasses made with the present technology are
shown in solid lines, and those made with conventional techniques
are shown with a dotted line (soda lime glass (SLG) and a mixed
barium borosilicate glass) where viscosities are low and the
glasses may be processed by conventional glass methods such as the
float glass process where many soda lime glasses are produced such
as ordinary window glasses. FIG. 1 also identifies the viscosity
behavior of many high temperature glasses (solid lines), such as
silica with 7.5 wt % titania, fused silica, silica with about 60
parts per million OH, silica with about 14 wt % GeO.sub.2, silica
with about 1 ppm OH, silica with about 150 ppm Cl, silica with 3.1
wt % B.sub.2O.sub.3 and 10.7 wt % TiO.sub.2. Characteristics for
glasses that may be uniquely processed with technology disclosed
herein are: anneal points (viscosities of 1013 poise) greater than
800.degree. C. and/or a silica (SiO.sub.2) content of greater than
85 wt %, such as with greater than 95 vol % amorphous or less than
5 vol % crystals present, such as no crystals present (amorphous).
Such glass may be in the form of rolls of high temperature annealed
glass. For some such embodiments, glass thicknesses less than about
400 .mu.m (e.g., less than 200 .mu.m) facilitate the glass to be
rollable in diameters less than a few meters, such as less than 1
meter, such as less than 0.5 meters.
[0428] Applicants have found that cooling rate differences
resulting from air flow differences, turbulence in air flow, as
well as radiative cooling or heating differences from surrounding
furnace environments or fixturing may produce localized stress
differences in the glass as the glass cools to temperatures below
the anneal point, which are locked into the glass. Compositional
variations may also impact glass viscosity, and these compositional
differences may result in different stresses, fictive temperatures,
index of refractions, thermal expansions. If the glass is next
re-heated to temperatures where the free standing glass could
deform, then unconstrained glass warpage may occur. Such reheating
may be needed in downstream processing, such as for thin film
deposition for example and warping may be undesirable. However,
Applicants have found that annealing glasses manufactured via
processes disclosed herein, such as by controlled cooling in a
multi-zone furnace, or by passage through an annealing furnace
subsequent to sintering (opposite the binder burnout system), helps
mitigate differences in tension across the article (e.g., sheet)
width as the glass is being rolled and/or helps mitigate instances
of different stress levels remaining trapped in the glass. Low and
uniform stress levels are identified in glass taken from the roll
and left free standing. More specifically, absolute stress levels
less than 10 MPa with variations across the article (e.g., sheet or
tape) less than +/-5 MPa are identified when the tape is freely
resting on a flat surface, such as with absolute stress levels less
than 5 MPa with variations less than +/-2 MPa, such as with
absolute stress fields less than 2 MPa with variations less than
+/-1 MPa. Some embodiments of the present disclosure include glass,
as described, having a relatively uniform structure in terms of
fictive temperature, such as variations less than +/-20.degree. C.,
such as less than +/-10.degree. C., such as less than +/-5.degree.
C. as measured by FTIR across a width of the respective article.
Uniform structure in terms of fictive temperature, may influence
properties of the glass, such as optical or thermal expansion of
the glass, such as where better expansivity may be obtained via
uniform lower fictive temperature, for example.
[0429] As indicated above, the present technology may be uniquely
suited to process thin ribbons or sheets of viscous, high
temperature amorphous glasses. Such glasses may have a viscosity of
12.5 poise only at temperatures exceeding 900.degree. C., where at
lower temperatures the viscosity is higher than 12.5; such as a
viscosity of 13 poise only at temperatures exceeding 900.degree.
C., such as only at temperatures exceeding 1000.degree. C., as
shown in FIG. 87. In other embodiments, glass (not limited to
viscous, high temperature amorphous glasses) may be manufactured to
have a granular profile via processes disclosed herein, such as
where the sintering temperatures are low enough to leave individual
grains or portions thereof, as shown with silica above in FIGS.
79A, 79B, and 80. The granular profile may be useful for light
scattering, for example. Still other embodiments may include
glasses such as chalcogenide, or glasses that have little or no
silica, which may be viscous, high temperature glasses.
[0430] Use of slurries for green tape and the sintering system
disclosed herein may help make glass with low solid inclusion
levels via purification processes and also low seed or low gaseous
inclusion levels. For example, liquid filtering of the slurry prior
to casting is one such process, such as for example where
sub-micron (e.g., 22 m.sup.2/g) powder mixed in the solvents may be
filtered through different size filters (40 to 200 .mu.m sieves for
example) in order to capture larger size solid defects, such as
solid oxide debris or organic debris such as hair. Also, debris may
be removed via different settling rates in suspensions, such as
where higher density agglomerated particles settle faster than
dispersed silica and lighter organic impurities rise to the
surface. A middle percentage, such as the middle 80%, could then be
used to cast. Centrifuges may accelerate the settling or rising
process.
[0431] Uniform, consistent and filtered slurry that has been
thoroughly degassed (or de-aired) prior to casting to create a very
uniform and consistent tape may help minimize the seed levels.
Index matching tapes may also facilitate detection of both seeds
and solid inclusions. The binder burn out step described above, to
remove organics, may occurs at temperatures less than 700.degree.
C., and oxygen at elevated temperatures may help remove final
residues of carbon, which could be trapped or react with silica to
create gases such as CO or CO.sub.2 and SiO.
[0432] The particularly thin forms of at least some articles
described herein have short permeation paths for gases, which
result in very little trapped gases even when air is used. To
further minimize trapping of insoluble gases such as argon,
nitrogen, and (to a lesser extent) oxygen, consolidation in an air
free atmosphere may be used, such as in vacuum and/or vacuum with
helium or hydrogen, or atmospheric helium or hydrogen, or mixtures
thereof. If the consolidating glass has trapped these gases (helium
or hydrogen), then the gases may permeate out of the structure in
minutes or seconds at any reasonable temperature greater than
1000.degree. C. and leave behind a vacuum or seed with no gases
present. The seed may then collapse from atmospheric pressure
combined with capillary stresses at temperatures where glass
deformation occur. In most, seed minimization would take place
preferably during the consolidation operation, prior to annealing.
However, the glass could be reheated to outgas trapped gas,
collapsed the seeds. and then annealed. Accordingly, at least some
embodiments include glass articles (e.g., rolls, tapes, sheets)
with little to no trapped gas, such as less than 5% by volume, such
as less than 3% by volume, such as less than 1% by volume.
[0433] Some embodiments of the present invention, as disclosed
above, may use rollers within the sintering furnace to control
tension, speed, deformation, or other attributes of the article
(e.g., tape or ribbon) during sintering. According to some
embodiments, the rollers rotate at different speeds from one
another, such as a function of shrinkage of the respective article.
For example, in at least one embodiment the furnace includes at
least two rollers, wherein a first roller interfaces with a less
sintered portion of the article, and the second roller interfaces
with a more sintered portion of the article. The second roller
rotates at a slower speed than the first roller. In some such
embodiments, rotation of the roller(s) within the furnace
correspond to free body sintering rates of the respective article
being sintered, or have a slightly greater speed to impart tension
in the article, such as to flatten the article or control warp. The
rollers may be made from refractory materials. Stationary supports
(e.g., furnace floor) may be located between rollers in the
furnace. In contemplated embodiments, multiple rows of rollers at
different levels within the furnace may be used, such as to
increase output and/or control airflow within the furnace. Such
rollers may be used with lengths of rigid materials, such as rods
or sheets.
[0434] FIGS. 88A to 88B show an embodiment of such a sintering
system. More specifically, FIG. 88A shows a sintering temperature
versus distance through the furnace of FIG. 88B for sintering
yttria-stabilized zirconia. The article (e.g., ribbon, tape) moves
from left to right through the furnace, from a first roll as an
unfired sheet (or less sintered tape) to a second roll as a
sintered ceramic sheet (or more sintered tape). Through the furnace
are rotating surfaces in the form of rollers that rotate with
normalized speeds ranging from 1.0 to 0.78, which are a function of
the rate of shrinkage of the yttria-stabilized zirconia. FIG. 89
shows a furnace with intermediate rollers, as shown in FIGS. 88A
and 88B, but with multiple levels. In some embodiments, a sintering
station or other furnace as disclosed herein includes more than one
tape or ribbon traversing the furnace at the same time. Referring
to FIGS. 90A and 90B, in other contemplated embodiments, moving
(e.g., rotating) surfaces within the furnace, other than rollers as
disclosed above, include belts, tracks, or other elements. Some
embodiments may include only a single belt or loop of tracks.
[0435] Referring to FIGS. 91A and 91B, an article (e.g., tape as
described above, sheet, etc.) comprises a lithium-containing
ceramic, specifically sintered Li.sub.6.1
La.sub.3Zr.sub.2Al.sub.0.3 O.sub.12 manufactured using technology
disclosed above. An excess lithium source, in the form of 6.7 wt %
Li.sub.2CO.sub.3, cast at 6 mil in acrylic binder (e.g., produced
by Elvacite) was processed in a binder burnout furnace with five
heat zones at temperatures of 180, 225, 280, 350, and 425.degree.
C., respectively, at a rate of 4 inches per minute. The article was
then sintered at 1125.degree. C. The resulting sintered article, as
shown in FIGS. 91A and 91B, consisted of greater than 80 percent by
weight (wt %) cubic lithium garnet crystals, such as greater than
90 wt %, such as greater than 95 wt %, such as consisted of about
99 wt % cubic lithium garnet crystals, as measured by x-ray
diffraction. Traditional approaches of sintering of lithium garnet,
such as batch sintering in a sealed crucibles, typically result in
higher percentages of non-cubic crystals. The resulting sintered
article, as shown in FIGS. 91A and 91B, had an ionic conductivity,
as measured by complex impedance analysis of greater than
5.times.10.sup.-5 S/cm, such as greater than 1.times.10.sup.-5
S/cm, such as about 1.72.times.10.sup.-5 S/cm. The resulting
sintered article, as shown in FIGS. 91A and 91B, had less than 10
percent by volume (vol %) porosity, such as less than 5 vol %,
and/or the corresponding porosity comprised at least some, most, at
least 80%, at least 90% closed porosity, meaning that pores were
completely sealed off. Applicants believe such characteristics are
due to the fast firing, tension control, air flow control, and
other technology disclosed herein.
[0436] Referring to FIG. 92, an article comprises a
lithium-containing ceramic, specifically sintered
Li.sub.5.39La.sub.3Zr.sub.1.7 W.sub.0.3 Ga.sub.0.5 O.sub.x with
"excess" lithium from 10.7 wt % Li.sub.2CO.sub.3 cast at 12 mil
("mil" is one thousandth of an inch) in acrylic binder and sintered
at 1050.degree. C. with the above-described technology. The image
in FIG. 92 is not polished, but shows closed porosity and
"pull-out" grains. Applicants have observed that the sintering
system of the present disclosure may result smaller grains in
sintered lithium-containing ceramic (garnet) when compared to
conventional sintering of "pills" in sealed crucibles. For example,
some articles of lithium-containing garnet of the present
disclosure have a grain size of 5 .mu.m or less, such as 3 .mu.m or
less. By "grain size," Applicants are referring to ASTM
E-112-13"Standard Test Methods for Determining Average Grain Size,"
using the basic linear intercept method, sections 12, 13 and 19 as
well as Paragraph A2.3.1, using Equation A2.9 average grain size is
1.5 times average intercept length for a spherical assumption of
grain shape. Smaller grain sizes may yield higher strength tapes or
other articles, which may be rolled without fracture on diameters
of cores disclosed herein. With that said, tapes or other articles
of lithium-containing ceramics may be produced using technology
disclosed herein with larger grain sizes, such as by starting with
larger grains or increasing sintering time.
[0437] In some embodiments, a lithium-containing garnet article
(e.g., sheet, tape) of the present disclosure may be integrated in
electronics, such as a solid state lithium battery as an
electrolyte, such as positioned between an anode and cathode, as
shown in FIG. 93 for example, with an electrically-conductive metal
current collector coupled to (e.g., bonded to, overlaying) the
lithium-containing garnet article, such as by way of the anode
and/or cathode. In other electronics, such as packaging
componentry, a metal layer may be directly bonded to, as in direct
contact with, a ceramic article as disclosed above. In contemplated
embodiments, the anode and/or the cathode may be tape cast as a
green tape and co-fired with the electrolyte, which may improve
performance of the electronics by enhancing electrolyte
interface(s) with the anode and/or cathode. Accordingly, articles
as disclosed herein may comprise layers, with thicknesses described
above for each layer (e.g., 100 .mu.m or less per layer) of two or
more different inorganic materials as disclosed herein sintered
from green tape and directly contacting and overlaying one another
and fired as disclosed above, as a thin co-fired tape for example.
The lithium-containing garnet in the electronics has closed pores,
few defects (as disclosed above), few or no pin holes, ionic
conductivity (as disclosed above), and/or small grain size (as
disclosed above).
[0438] Referring to FIGS. 94 and 95, two example firing cycles for
lithium-containing are shown. Such temperature versus time profiles
may be implemented by rate of moving articles, as disclosed herein,
through the presently disclosed sintering system, and by
controlling heat zones within the system to provide such heating.
Alternatively, shorter length articles may be moved into and out of
furnaces as disclosed herein, and held stationary within such
furnaces to control sintering time, for example. As shown in FIGS.
93 and 94, sintering time (i.e. time at temperatures that induce
sintering) is relatively short, such as less than 2000 seconds per
cycle. In some embodiments, the same article may be sintered in
multiple cycles, such as in a first cycle at a first level of
tension and first peak temperature, and then in a second cycle of
different tension, temperature, and/or time cycle time, which may
help control distortion of the article due to shrinkage during
sintering.
[0439] Applicants have found that use of "excess" volatile
constituents (e.g., lithium) in the green material greatly improves
resulting ceramic tape. For example, without excess lithium,
lithium lost from garnet due to vaporization may result in a second
phase material, such as La.sub.2Zr.sub.2O.sub.7"pyrochlore," which
may act as an insulator and inhibit sintering. Accordingly, ceramic
with pyrochlore may result the material that is highly porous,
mechanically weak, and/or has poor conductivity. Put another way,
Applicants believe that cubic phase, sintering extent and density
(inverse of porosity), strength, and ionic conductivity all
decrease as pyrochlore phase increases, such as from lithium
loss.
[0440] FIGS. 96 and 97 show ionic conductivity (FIG. 96) and weight
percentage of cubic garnet for Li.sub.5.39La.sub.3Zr.sub.1.7
W.sub.0.3 Ga.sub.0.5 O.sub.x with 10.7 wt % Li.sub.2CO.sub.3 as a
source of excess lithium, as described above, either pre-reacted
("PR") or not, with a 3 minute sintering time, as shown in FIG. 94,
or a 15 minute sintering time, as shown in FIG. 95. The open dots
in FIG. 96 are interpolated. Each of the examples in FIG. 96 had
ionic conductivity of greater than 5.times.10.sup.-5 S/cm, and some
had greater than 2.times.10.sup.-4 S/cm, such as greater than
3.times.10.sup.-4 S/cm. Surprisingly, the shorter sintering times
generally resulted in higher ionic conductivity, which may be
synergistic in terms of production efficiency. Referring to FIG.
97, each of the examples had greater than 90 wt % cubic garnet,
such as greater than 93 wt % cubic garnet, and some had greater
than 95 wt %. By comparison,
Li.sub.6.1La.sub.3Zr.sub.2Al.sub.0.3O.sub.12 with 6.7 wt %
Li.sub.2CO.sub.3 excess lithium source cast at 6 mil in acrylic
binder and sintered at 1030.degree. C. resulted in 33 wt % cubic
and 3.84.times.10.sup.-6 S/cm conductivity.
[0441] In other examples,
Li.sub.6.5La.sub.3Zr.sub.1.5Ta.sub.0.5O.sub.12 with 11.98 wt %
Li.sub.2CO.sub.3 added in the slip of the tape cast, cast with 10
mil blade, had binder burned off in an argon atmosphere, and then
was sintered using the technology disclosed herein for 15 or 8
minutes in air. FIGS. 85A and 85B show a green tape of
Li.sub.6.5La.sub.3Zr.sub.1.5Ta.sub.0.5O.sub.12 with 11.98 wt %
Li.sub.2CO.sub.3, where the unfired median particle size (D.sub.50)
about 0.60 micrometers, the tape thickness was about 85 to 88
micrometers, and the slip was about 18 vol % solid. FIGS. 98 and 99
show micrographs of a corresponding sintered tape after 15 minutes
sintering at about 1200.degree. C. The sintered tape of FIGS. 98
and 99 is about 54 micrometers thick due to about 37 to 38%
shrinkage. As can be seen in FIG. 99, the tape includes some closed
pores but no pin holes. FIGS. 100A and 100B show micrographs of a
first major surface of the sintered tape of FIGS. 98 and 99, and
FIGS. 101A and 101B show the second major surface. The surfaces
have a granular profile. Grain size is between about 1 to 5
micrometers, on average, with some grains as large as about 10
micrometers. Ionic conductivity was measured to be
3.83.times.10.sup.-4 S/cm using standard complex impedance
analysis. Phase quantification showed 96 wt % cubic garnet. For a
similar sample instead sintered for 8 minutes, about 100 wt % cubic
garnet. In another Li.sub.6.5La.sub.3Zr.sub.1.5Ta.sub.0.5O.sub.12
sample, with instead 6.7% excess Li.sub.2CO.sub.3 added and
sintered at 1150.degree. C. for 3 minutes, conductivity was about
1.18.times.10.sup.-4 S/cm. Some lithium-containing ceramics
included silicone added to the green tape that became silica in the
sintered article, which Applicants believe may strengthen the
sintered article, such as 2 wt % M97E Silicone (SILRES.RTM.) added
to the MAA with 10.7 wt % Li.sub.2CO.sub.3, and sintered at
1050.degree. C. for 3 minutes, resulting in 2.38.times.10.sup.-4
S/cm conductivity. When sintered at 1100.degree. C. for 3 minutes,
the same material combination had 2.59.times.10.sup.-4 S/cm
conductivity. In another example 7 wt % of LiOH excess lithium
source was added to MAA and sintered at 1200.degree. for 3 minutes,
resulting in 1.97.times.10.sup.-4 S/cm conductivity.
[0442] As indicated above, the present technology (e.g., binder
burn-off, sintering station with multi-heat zones and air flow
control, tension control, etc.) may be used to sinter green
material (tape or other articles) to have the structures,
geometries, and properties/attributes disclosed herein, such as
green material that includes an organic binder (e.g., polyvinyl
butyral, dibutyl phthalate, polyalkyl carbonate, acrylic polymers,
polyesters, silicones, etc.) supporting particles of inorganic
material, such as polycrystalline ceramic, synthetic mineral,
viscous glasses that may be hard to otherwise process into a thin
tape or ribbon structure for roll-to-roll manufacturing, or other
inorganic materials (e.g., metals, less viscous glasses). For
example, the inorganic materials include zirconia (e.g.,
yttria-stabilized zirconia, nickel-yttria stabilized zirconia
cermet, NiO/YSZ), alumina, spinel (e.g., MgAl.sub.2O.sub.4, zinc
ferrite, NiZn spinel ferrite, or other minerals that may
crystallize as cubic and include the formulation of
A.sub.2+B.sub.2.sup.3+O.sub.4.sup.2-, where A and B are cations and
may be magnesium, zinc, aluminum, chromium, titanium, silicon, and
where oxygen is the anion except for chalcogenides, such as
thiospinel), silicate minerals such as garnet (e.g., lithium garnet
or lithium-containing garnet, of formula
X.sub.3Z.sub.2(TO.sub.4).sub.3 where X is Ca, Fe, etc., Z is Al,
Cr, etc., T is Si, As, V, Fe, Al), lithium lanthanum zirconium
oxide (LLZO), cordierite, mullite, perovskite (e.g., porous
perovskite-structured ceramics), pyrochlore, silicon carbide,
silicon nitride, boron carbide, sodium bismuth titanate, barium
titanate (e.g., doped barium titanate), magnesium titanium oxide,
barium neodymium titanate, titanium diboride, silicon alumina
nitride, aluminum nitride, silicon nitride, aluminum oxynitride,
reactive cerammed glass-ceramic (a glass ceramic formed by a
combination of chemical reaction and devitrification, which
includes an in situ reaction between a glass frit and a reactant
powder(s)), silica, doped silica, ferrite (e.g., NiCuZnFeO ferrite,
BaCO ferrite), lithium-containing ceramic, including lithium
manganate, lithium oxide, viscous glasses as discussed above, such
as high-melting temperature glasses, glasses with a Tg greater than
1000.degree. C. at standard atmospheric pressure, high purity fused
silica, silica with an SiO.sub.2 content of at least 99% by volume,
silica comprising a granular profile, a silica tape without a
repeating pattern of waves or striae extending across a width of
the tape, iron sulfide, piezoelectric ceramic, potassium niobate,
silicon carbide, sapphire, yttria, cermet, steatite, forsterite,
lithium-containing ceramics (e.g., gamma-LiAlO.sub.2), transition
metal oxide (e.g., lithium manganite, which may also be a spinel,
ferrite), materials with volatile constituents as described above
(e.g., lithium manganite (again)) lead oxide, garnets,
alkali-containing materials, sodium oxide, glass-ceramic particles
(e.g. LAS lithium aluminosilicates), and other inorganic materials
as disclosed herein or otherwise.
[0443] In contemplated embodiments, inorganic binders like
colloidal silica, alumina, zirconia, and hydrates thereof may be
used in place of or in combination with organic binders as
disclosed herein, such as to strengthen the tape. Applicants have
found that stronger tape makes the sintering process more robust in
terms of stability and access to a wider process space, such as
greater tension. In some embodiments, a green material (e.g., green
tape) as used herein, includes an inorganic binder. For example, a
source of tape material may comprise a green tape and a carrier web
supporting the green tape, the green tape comprising grains of
inorganic material and an inorganic binder in an organic binder. In
some embodiments, inorganic particles, such as inorganic binder
includes particles of about 5 nm to about 100 micrometers in
D.sub.50 particle size.
[0444] In contemplated embodiments, materials, such as ceramics
disclosed herein, may be fired to have a high degree of porosity,
such as greater than 20% by volume, such as greater than 50%, such
as greater than 70%, and/or such materials may then be filled with
a polymeric filler. Use of partially sintered inorganic material,
as disclosed herein may have advantages over loose inorganic
material in a composite because the partially sintered inorganic
material may serve as a rigid skeleton to hold shape of the
composite at high temperatures where the polymeric filler softens.
Accordingly, some embodiments include a composite tape having
dimensions disclosed above, of partially sintered ceramic, where
(at least some, most, almost all) particles are the ceramic are
sintered to one another and/or where porosity of the ceramic is at
least partially, mostly, or fully filled with a polymer filler.
[0445] As indicated above, in some embodiments different inorganic
materials may be co-fired using technology disclosed herein, such
as discrete layers of the different inorganic materials (e.g.,
anode plus electrolyte of solid state battery), or in other
arrangements, such as an evenly distributed mixture of two or more
inorganic materials co-fired, such as to influence thermal
expansion, strength, or other characteristics of the resulting
article. In some embodiments, glass and ceramic may be co-fired,
such as where a glass phase is mixed with particles of ceramic. For
example, FIG. 102 shows low-temperature co-fired ceramic tape
(glass and alumina) sintered at 1000.degree. C. using a sintering
station comprising an air bearing such that the tape was sintered
without direct contact with walls/floors in the furnace.
[0446] Some embodiments of the present disclosure include an
article (e.g., sheet, tape or ribbon), such as of inorganic
material, such as ceramic, such as alumina or zirconia, with a
granular profile and a layer (or coating) overlaying the granular
profile to reduce roughness of the granular profile, such as on one
or more major surfaces of the article. The layer may be applied in
a liquid form through spin coating, slot die coating, spray
coating, dip coating, or other processes. In some embodiments, the
layer may be amorphous and inorganic, such as glass or converted
into solid glass upon thermal annealing or curing. In some such
embodiments, the layer is mostly silicon and oxygen, such as with
some phosphorous, boron, carbon, nitrogen or other constituents.
The layer may also include oxides of Ti, Hf, and/or Al. Such a
layer may be applied and cured as part of the same manufacturing
line as the binder burnout and sintering, and the resulting article
(e.g., tape) may be rolled and include the layer when rolled. In
some embodiments, the layer is annealed at temperatures of
850.degree. C. or higher and is very thin, such as a positive
thickness less than a micrometer, such as less than 560 nm. In some
embodiments, roughness of the layer is less than half that of the
granular profile, such as less than a third. In some embodiments,
roughness of the layer is less than 15 nm, such as about 5 nm
average roughness (Ra or Rq) over a distance of 1 cm along a single
axis.
[0447] In yttrium-stabilized zirconia and alumina articles were
laser cut into 30.times.30 mm squares and coated by spin-on-glass,
spin coating techniques. A pure silica solution (Desert Silicon NDG
series) was tested along with a lightly doped (10.sup.21
atoms/cm.sup.3) phosphorous-doped silica solution (Desert Silicon
P-210). The solution was applied in a liquid form, and upon curing
solidified. A final anneal densified the glass film. The solutions
were applied using spin coating. Samples were then cured either in
a hotplate at temperatures between 150.degree. C. and 200.degree.
C. or in a vacuum oven with temperatures between 170.degree. C. and
250.degree. C. After the initial cure, samples were annealed in
nitrogen atmosphere at temperatures between 850.degree. C. and
1000.degree. C. One-inch square silicon pieces were processed in
parallel to the ceramic pieces to provide "witness" samples, used
to accurately measure the glass film thickness using optical
ellipsometer.
[0448] In one example a sheet of 40 .mu.m thick alumina was coated
with phosphorous-doped silica (Desert Silicon P210) by spinning at
1500 revolutions per minute (rpm) for 60 seconds, with 133
rpm/second acceleration, resulting in a coating of about 320 nm
thick, 15.3 nm Ra, 12.1 nm Rq, 130 nm Z.sub.max on one side and
25.9 nm Ra, 20 nm Rq, and 197 nm Z.sub.max on the other, where the
coated layer had good film quality after furnace anneal at
850.degree. C., with no cracking. In another example a sheet of 40
.mu.m thick alumina was coated with non-doped silica (Desert
Silicon NDG-2000) by spinning at 1500 revolutions per minute (rpm)
for 60 seconds, with 133 rpm/second acceleration, resulting in a
coating of about 444 nm thick, 11 nm Ra, 8.8 nm Rq, 79.4 nm
Z.sub.max on one side and 22.6 nm Ra, 17 nm Rq, and 175 nm
Z.sub.max on the other, again where the coated layer had good film
quality after furnace anneal at 850.degree. C., with no cracking.
By contrast, in another example a sheet of 40 .mu.m thick alumina
was coated with non-doped silica (Desert Silicon P210) by spinning
at 4000 revolutions per minute (rpm) for 60 seconds, with 399
rpm/second acceleration, resulting in a coating of about 946 nm
thick, 5.1 nm Ra, 6.5 nm Rq, 48 nm Z.sub.max on one side and 10.8
nm Ra, 14 nm Rq, and 89 nm Z.sub.max on the other, where the coated
layer had pronounced cracking after furnace anneal at 850.degree.
C.
[0449] In one example a sheet of 40 .mu.m thick yttria-stabilized
zirconia was coated with non-doped silica (Desert Silicon NDG-2000)
by spinning at 2000 revolutions per minute (rpm) for 60 seconds,
with 1995 rpm/second acceleration, resulting in a coating of about
258 nm thick, 5.9 nm Ra, 4.7 nm Rq, 92 nm Z.sub.max on one side,
where the coated layer had good film quality after furnace anneal
at 1000.degree. C. for 60 minutes, with no cracking. In another
example a sheet of 40 .mu.m thick yttria-stabilized zirconia was
coated with phosphorous-doped silica (Desert Silicon P210) by
spinning at 1500 revolutions per minute (rpm) for 60 seconds, with
133 rpm/second acceleration, resulting in a coating of about 320 nm
thick, 8.9 nm Ra, 11.7 nm Rq, 135 nm Z.sub.max on one side, again
where the coated layer had good film quality after furnace anneal
at 850.degree. C. for 30 minutes, with no cracking. By contrast, in
another example a sheet of 40 .mu.m thick yttria-stabilized
zirconia was coated with non-doped silica (Desert Silicon P210) by
spinning at 1500 revolutions per minute (rpm) for 60 seconds, with
133 rpm/second acceleration, resulting in a coating of about 444 nm
thick, 7.7 nm Ra, 9.5 nm Rq, 75 nm Z.sub.max on one side, where the
coated layer had some cracking after furnace anneal at 850.degree.
C. Surface morphology of the samples was measured using
Atomic-Force-Microscopy on a 10 micron field of view. FIG. 103, for
example, shows an electron microscope image of pure silica (Desert
Silicon NDG-2000) coated yttria-stabilized zirconia. The layer of
silica is about 250 nm thick. Such layers may improve dielectric
properties of the tape, and/or serve as a barrier layer to prevent
transmission of impurities to/from the underlying material. For
example, such layers may be used with LEDs, as disclosed above, or
other electronics and packaging, and/or may be applied to sintered
tape and rolled as a roll of the tape, as disclosed herein. In
other contemplated embodiments, the layer may be another inorganic
material, or a polymeric material, such as for different uses.
[0450] Aspects of the present disclosure relate to a sintered
article that comprises (1) a first major surface, (2) a second
major surface opposing the first major surface, and (3) a body
extending between the first and second surfaces, where the body
comprises a sintered inorganic material, where the body has a
thickness (t) defined as a distance between the first major surface
and the second major surface, a width defined as a first dimension
of one of the first or second surfaces orthogonal to the thickness,
and a length defined as a second dimension of one of the first or
second surfaces orthogonal to both the thickness and the width, and
where the width is about 5 mm or greater, the thickness is in a
range from about 3 .mu.m to about 1 mm, and the length is about 300
cm or greater. This sintered article may be such that the inorganic
material comprises an interface having a major interface dimension
of less than about 1 mm, where the interface comprises either one
of or both a chemical inhomogeneity and crystal structure
inhomogeneity, and optionally where the inorganic material
comprises a ceramic material or a glass ceramic material and/or
where the inorganic material comprises any one of a piezoelectric
material, a thermoelectric material, a pyroelectric material, a
variable resistance material, or an optoelectric material. In some
such embodiments, the inorganic material comprises one of zirconia,
alumina, spinel, garnet, lithium lanthanum zirconium oxide (LLZO),
cordierite, mullite, perovskite, pyrochlore, silicon carbide,
silicon nitride, boron carbide, sodium bismuth titanate, barium
titanate, titanium diboride, silicon alumina nitride, aluminum
oxynitride, or a reactive cerammed glass-ceramic. In any one of the
above sintered articles, the sintered article may comprise at least
ten square centimeters of area along the length that has a
composition where at least one constituent of the composition
varies by less than about 3 weight %, across the area; and/or where
the sintered article comprises at least ten square centimeters of
area along the length that has a crystalline structure with at
least one phase having a weight percent that varies by less than
about 5 percentage points, across the area; and/or where the
sintered article comprises at least ten square centimeters of area
along the length that has a porosity that varies by less than about
20%; and/or where one or both the first major surface and the
second major surface has a granular profile comprising grains with
a height in a range from 25 nm to 150 .mu.m relative to recessed
portions of the respective surface at boundaries between the
grains; and/or where one or both the first major surface and the
second major surface has a flatness in the range of 100 nm to 50
.mu.m over a distance of one centimeter along the length or the
width; and/or where one of or both the first major surface and the
second major surface comprises at least ten square centimeters of
area having fewer than one hundred surface defects from adhesion or
abrasion with a dimension greater than 5 .mu.m, such as optionally
where the other of the first major surface and the second major
surface comprises surface defects from adhesion or abrasions with a
dimension of greater than 5 .mu.m; and/or further comprising a
striated profile along the width dimensions, wherein the thickness
is within a range from about 0.9 t to about 1.1 t, such as where
the striated profile comprises 2 or more undulations along the
width and/or where the striated profile comprises less than 20
undulations along the width.
[0451] Aspects of the present disclosure relate to a sintered
article, comprising (1) a first major surface, (2) a second major
surface opposing the first major surface, and (3) a body extending
between the first and second surfaces, the body comprising a
sintered inorganic material,
[0452] where the body has a thickness (t) defined as a distance
between the first major surface and the second major surface, a
width defined as a first dimension of one of the first or second
surfaces orthogonal to the thickness, and a length defined as a
second dimension of one of the first or second surfaces orthogonal
to both the thickness and the width, and where (at least) a portion
of the sintered article is flattenable. In some such sintered
articles, the article, when flattened, exhibits a maximum in plane
stress (the absolute value of stress, as measured by the thin plate
bend bending equation) of less than or equal to 25% of the bend
strength (measured by 2-point bend strength) of the article; and/or
the article, when flattened, exhibits a maximum in plane stress
(the absolute value of stress, as measured by the thin plate bend
bending equation) of less than or equal to 1% of the Young's
modulus of the article. In some such embodiments, where the article
has a thickness of about 80 .mu.m and a bend radius of greater than
0.03 m, the article exhibits a maximum in plane stress (the
absolute value of stress, as measured by the thin plate bend
bending equation) of less than or equal to 25% of the bend strength
(measured by 2-point bend strength) of the article; or where the
article has a thickness of about 40 .mu.m and a bend radius of
greater than 0.015 m, the article exhibits a maximum in plane
stress (the absolute value of stress, as measured by the thin plate
bend bending equation) of less than or equal to 25% of the bend
strength (measured by 2-point bend strength) of the article; or
where the article has a thickness of about 20 .mu.m and a bend
radius of greater than 0.0075 m, the article exhibits a maximum in
plane stress (the absolute value of stress, as measured by the thin
plate bend bending equation) of less than or equal to 25% of the
bend strength (measured by 2-point bend strength) of the article.
In some such embodiments, the width of the sintered article is
about 5 mm or greater, the thickness is in a range from about 3
.mu.m to about 1 mm, and the length is about 300 cm or greater,
and/or the portion of the sintered article that is flattenable
comprises a length of about 10 cm. In some such embodiments, one or
both the first major surface and the second major surface has a
flatness in the range of 100 nm to 50 .mu.m over a distance of one
centimeter along the length or the width. In some such embodiments,
the inorganic material comprises a ceramic material or a glass
ceramic material; the inorganic material comprises any one of a
piezoelectric material, a thermoelectric material, a pyroelectric
material, a variable resistance material, or an optoelectric
material; and/or the inorganic material comprises one of zirconia,
alumina, spinel, garnet, lithium lanthanum zirconium oxide (LLZO),
cordierite, mullite, perovskite, pyrochlore, silicon carbide,
silicon nitride, boron carbide, sodium bismuth titanate, barium
titanate, titanium diboride, silicon alumina nitride, aluminum
oxynitride, or a reactive cerammed glass-ceramic. In some such
embodiments, the sintered article comprises at least ten square
centimeters of area along the length that has a composition where
at least one constituent of the composition varies by less than
about 3 weight %, across the area; and/or the sintered article
comprises at least ten square centimeters of area along the length
that has a crystalline structure with at least one phase having a
weight percent that varies by less than about 5 percentage points,
across the area; and/or the sintered article comprises at least 10
square centimeters of area along the length that has a porosity
varies by less than about 20%, across the area; and/or one or both
the first major surface and the second major surface has a granular
profile comprising grains with a height in a range from 25 nm to
150 .mu.m relative to recessed portions of the respective surface
at boundaries between the grains; and/or one or both the first
major surface and the second major surface has a flatness in the
range of 100 nm to 50 .mu.m over a distance of one centimeter along
the length or the width; and/or one of or both the first major
surface and the second major surface comprises have at least ten
square centimeters of area having fewer than one hundred surface
defects from adhesion or abrasion with a dimension greater than 5
.mu.m, such as where the other of the first major surface and the
second major surface comprises surface defects from adhesion or
abrasions with a dimension of greater than 5 .mu.m; and/or the
sintered article further comprising a striated profile along the
width dimensions, wherein the thickness is within a range from
about 0.9 t to about 1.1 t, such as where the striated profile
comprises 2 or more undulations along the width; and/or the article
comprises a saddle shape; and/or the article comprises a c-shape
having a concave shape along the length.
[0453] Aspects of the present disclosure relate to a rolled
sintered article comprising (1) a core having a diameter of less
than 60 cm and (2) a continuous sintered article wound around the
core, the continuous sintered article comprising (2a) a first major
surface, (2b) a second major surface opposing the first major
surface, (2c) a body extending between the first and second
surfaces, the body comprising a sintered inorganic material, where
the body has a thickness (t) defined as a distance between the
first major surface and the second major surface, a width defined
as a first dimension of one of the first or second surfaces
orthogonal to the thickness, and a length defined as a second
dimension of one of the first or second surfaces orthogonal to both
the thickness and the width, and where the width is about 5 mm or
greater, the thickness is in a range from about 3 .mu.m to about 1
mm, and the length is about 30 cm or greater. In some such
embodiments, the continuous sintered article is disposed on an
interlayer support material, and the continuous sintered article
and interlayer support material are wound around the core such that
each successive wrap of the continuous sintered article is
separated from one another by the interlayer support material, such
as where the interlayer support material comprises a first major
surface and a second major surface opposing the first major
surface, an interlayer thickness (t) defined as a distance between
the first major surface and the second major surface, an interlayer
width defined as a first dimension of one of the first or second
surfaces orthogonal to the interlayer thickness, and an interlayer
length defined as a second dimension of one of the first or second
major surfaces orthogonal to both the interlayer thickness and the
interlayer width of the interlayer support material, and where the
interlayer thickness is greater than the thickness of the sintered
article and/or where the inlayer comprises a tension that is
greater than a tension on the continuous sintered article, as
measured by a load cell, and/or where the rolled article comprises
a diameter and a side wall width that are substantially constant,
and/or where the core comprises a circumference and a core
centerline along the circumference, where the continuous sintered
article comprises an article centerline along a direction of the
length, and where distance between the core centerline and the
article centerline is 2.5 mm or less, along the length of the
continuous sintered article, and/or where the interlayer support
material is compliant, and/or where the interlayer width is greater
than the width of the continuous sintered article, and/or where the
interlayer support material comprises any one or both a polymer and
a paper, such as where the polymer comprises a foamed polymer, such
as where the foamed polymer is closed cell.
[0454] Aspects of the present disclosure relate to a plurality of
sintered articles each comprising (1) a first major surface, (2) a
second major surface opposing the first major surface, and (3) a
body extending between the first and second surfaces, the body
comprising a sintered inorganic material, where the body has a
thickness (t) defined as a distance between the first major surface
and the second major surface, a width defined as a first dimension
of one of the first or second surfaces orthogonal to the thickness,
and a length defined as a second dimension of one of the first or
second surfaces orthogonal to both the thickness and the width, and
where each of the plurality of sintered articles is flattenable. In
some such embodiments, each article, when flattened, exhibits a
maximum in plane stress (the absolute value of stress, as measured
by the thin plate bend bending equation) of less than or equal to
25% of the bend strength (measured by 2-point bend strength) of the
article; and/or each article, when flattened, exhibits a maximum in
plane stress (the absolute value of stress, as measured by the thin
plate bend bending equation) of less than or equal to 10% of the
Young's modulus of the article. In some such embodiments, where
each article has a thickness of about 80 .mu.m and a bend radius of
greater than 0.03 m, the article exhibits a maximum in plane stress
(the absolute value of stress, as measured by the thin plate bend
bending equation) of less than or equal to 25% of the bend strength
(measured by 2-point bend strength) of the article; and/or where
each article has a thickness of about 40 .mu.m and a bend radius of
greater than 0.015 m, the article exhibits a maximum in plane
stress (the absolute value of stress, as measured by the thin plate
bend bending equation) of less than or equal to 25% of the bend
strength (measured by 2-point bend strength) of the article; and/or
where the article has a thickness of about 20 .mu.m and a bend
radius of greater than 0.0075 m, the article exhibits a maximum in
plane stress (the absolute value of stress, as measured by the thin
plate bend bending equation) of less than or equal to 25% of the
bend strength (measured by 2-point bend strength) of the article.
In some such embodiments, the thickness of the plurality of
sintered articles is within a range from about 0.7 t to about 1.3
t; and/or at least 50% of the sintered articles comprises an area
and a composition, where at least one constituent of the
composition varies by less than about 3 weight % across the area;
and/or at least 50% the sintered articles comprise an area and a
crystalline structure with at least one phase having a weight
percent that varies by less than about 5 percentage points across
the area; and/or at least 50% of the sintered articles comprise an
area and a porosity that varies by less than about 20% across the
area.
[0455] Aspects of the present disclosure relate to a separation
system for separating two materials, where the separation system
comprises a source of a continuous tape material comprising a green
tape material and a carrier web supporting the green tape material;
a vacuum drum positioned in proximity to the source of a continuous
tape material and configured to receive and convey the continuous
material from the source to a peeler, where the vacuum drum
comprises a plurality of vacuum holes for facilitating applying
tension by the separation system to the carrier web that is greater
than a tension applied to the green tape material, as the
continuous roll is conveyed to the peeler; and a peeler for
directing the carrier web in a rewind direction and directing the
green tape material in a downstream processing direction that
differs from the rewind direction. In some such embodiments, the
source of continuous tape material comprises a spool or a belt
comprising the continuous material wound thereon. In some
embodiments, the rewind and downstream processing directions form
an angle therebetween that is greater than about 90 degrees. In at
least some of such embodiments, the separation system applies
essentially no tension to the green tape material (excluding weight
of the green tape itself). In at least some of such embodiments,
the tension applied to the carrier web at least 2 times greater
than the tension applied to the green tape material. In at least
some of such embodiments, the peeler comprises a tip that separates
the carrier web from the green tape material before directing the
carrier web in a rewind direction and directing the green tape
material in a downstream processing direction that differs from the
rewind direction. In at least some of such embodiments, the peeler
comprises a tip that separates the carrier web from the green tape
material simultaneously with directing the carrier web in a rewind
direction and directing the green tape material in a downstream
processing direction that differs from the rewind direction, where
the tip may comprise a radius of about 0.05 inches or less. In at
least some of such embodiments, the separation system further
comprises a furnace for sintering the green tape material, an
uptake reel for spooling the carrier web, and/or a load controller
for maintaining the tension on the carrier web.
[0456] Other aspects of the present disclosure include a separation
system for separating two materials, which comprises a source of a
continuous tape material comprising a green tape material disposed
on a carrier web, the carrier web comprising a first tension; a
tension isolator positioned in proximity to the source configured
to apply a second tension to carrier web that is greater than the
first tension when conveying the continuous material to a peeler;
and a peeler for directing the carrier web in a rewind direction
and directing the green tape material in a downstream processing
direction that differs from the rewind direction. In at least some
of such embodiments (any one or more of the above embodiments), the
source comprises a spool or a belt comprising the continuous
material. In at least some of such embodiments, the rewind
direction and the downstream processing direction form an angle
that is greater than about 90 degrees. In at least some of such
embodiments, the second tension is about 2.5 pounds per linear inch
of width or less. In at least some of such embodiments, the first
tension is equal to or less than about 50% of the second tension.
In at least some of such embodiments, the peeler comprises a tip
that separates the carrier web from the green tape material before
directing the carrier web in a rewind direction and directing the
green tape material in a downstream processing direction that
differs from the rewind direction; and/or the tip that separates
the carrier web from the green tape material simultaneously with
directing the carrier web in a rewind direction and directing the
green tape material in a downstream processing direction that
differs from the rewind direction; where in neither, either, or
both such embodiments the tip comprises a radius of about 0.05
inches or less. In at least some of such embodiments, the tension
isolator comprises a vacuum drum comprising a plurality of vacuum
holes that apply the second tension to the carrier web. In at least
some of such embodiments, the separation system further comprises a
furnace for sintering the green tape material, an uptake reel for
spooling the carrier web, and/or a load controller for maintaining
the tension on the carrier web.
[0457] Aspects of the present disclosure relate to a method for
separating two materials, the method comprising steps, not
necessarily in the following order, of (1) feeding a continuous
material to a tension isolator, the continuous material comprising
a green tape material disposed on a carrier web, (2) applying
tension to the carrier web that is greater than a tension applied
to the green tape material with the tension isolator, and (3)
directing the carrier web to move in a rewind direction and
directing the green tape material in a downstream processing
direction that differs from the rewind direction. In at least some
such embodiments, the method further comprises a step of separating
the carrier web from the green tape material before directing the
carrier web in a rewind direction and directing the green tape
material in a downstream processing direction that differs from the
rewind direction, and/or separating the carrier web from the green
tape material simultaneously with directing the carrier web in a
rewind direction and directing the green tape material in a
downstream processing direction that differs from the rewind
direction, such as where the rewind direction and the downstream
processing direction form an angle that is greater than about 90
degrees. In at least some such embodiments, the method further
comprises a step of applying essentially no tension to the green
tape material, such as where the tension applied to the carrier web
at least 2 times greater than the tension applied to the green tape
material. In at least some such embodiments, the method further
comprises a step of at least partially sintering the green tape
material. In at least some such embodiments, the method further
comprises a step of spooling the carrier web onto an uptake reel.
In at least some such embodiments, the method further comprises a
step of maintaining the tension on the carrier web.
[0458] Aspects of the present disclosure relate to a method for
separating two continuous materials, where the method comprises
steps, not necessarily in the following order, of (1) feeding a
continuous tape material comprising a green tape supported on a
carrier web to a tension isolator and applying a first tension to
the carrier web; (2) applying a second tension to the carrier web
that is greater than the first tension; and (3) directing the
carrier web to move in a rewind direction and directing the green
tape material in a downstream processing direction that differs
from the rewind direction. In at least some such embodiments, the
method further comprises a step of separating the carrier web from
the green tape material before directing the carrier web in a
rewind direction and directing the green tape material in a
downstream processing direction that differs from the rewind
direction and/or separating the carrier web from the green tape
material simultaneously with directing the carrier web in a rewind
direction and directing the green tape material in a downstream
processing direction that differs from the rewind direction, such
as where the rewind direction and the downstream processing
direction form an angle that is greater than about 90 degrees. In
at least some such embodiments, the method further comprises a step
of applying a first tension comprises applying essentially no
tension (i.e. very little as disclosed herein). In at least some
such embodiments, the second tension is about 2.5 pounds per linear
inch of width or less. In at least some such embodiments, the first
tension is equal to or less than about 50% of the second tension.
In at least some such embodiments, the method further comprises a
step of at least partially sintering the green tape material,
spooling the carrier web onto an uptake reel, and/or maintaining
the tension on the carrier web.
[0459] Aspects of the present disclosure relate to a roll-to-roll
tape sintering system, the system comprising (1) an input roll of a
length of tape material comprising grains of inorganic material,
the inorganic material of the tape material on the input roll
having a first porosity; (2) a sintering station comprising (2a) an
entrance, (2b) an exit, (2c) a channel extending between the
entrance and the exit, and (2d) a heater heating the channel to a
temperature greater than 500 degrees C., where the exit, the
entrance, and the channel of the sintering station lie in a
substantially horizontal plane, such that an angle defined between
the exit and the entrance relative to a horizontal plane is less
than 10 degrees, and where the tape material passes from the input
roll, into the entrance of the sintering station, through the
channel of the sintering station and out of the exit of the
sintering station and heat within the channel sinters the inorganic
material of the tape material; and (3) an uptake roll winding the
length of tape material following exit from the sintering station,
where the inorganic material of the tape material on the uptake
roll has a second porosity that is less than the first porosity. In
at least some such embodiments, the angle defined between the exit
and the entrance relative to a horizontal plane is less than 1
degree. In at least some such embodiments, the tape material on the
input roll has a width greater than 5 mm and a length greater than
10 m. In at least some such embodiments, the tape material on the
input roll has a thickness between 3 microns and 1 millimeter. In
at least some such embodiments, the tape material moves through the
sintering station at a high speed of greater than 6 inches per
minute. In at least some such embodiments, the tape material on the
input role includes an organic binder material supporting the
grains of inorganic material, and the system further comprises (4)
a binder removal station located between the input roll and the
sintering station, the binder removal station comprising (4a) an
entrance, (4b) an exit, (4c) a channel extending between the
entrance and the exit, and (4d) a heater heating the channel to a
temperature between 200 degrees C. and 500 degrees C., wherein the
exit of the binder station, the entrance of the binder station, and
the channel of the binder station lie in a substantially horizontal
plane such that an angle defined between the exit of the binder
station and the entrance of the binder station relative to a
horizontal plane is less than 10 degrees, where the channel of the
binder station is aligned with the channel of the sintering station
such that the tape material passes from the input roll, into the
entrance of the binder removal station, through the channel of the
binder removal station and out of the exit of the binder removal
station into the entrance of the sintering station while moving in
a substantially horizontal direction, where heat within the channel
of the binder removal station chemically changes and/or removes at
least a portion of the organic binder material prior to the tape
material entering the sintering station. In at least some such
embodiments, the heater of the sintering station includes at least
two independently controlled heating elements, the heating elements
generate a temperature profile along the length of the channel of
the sintering station that increases along the channel in a
direction from the entrance toward the exit; where in some such
embodiments the temperature profile is shaped such that stress at
edges of the tape material during sintering remains below an edge
stress threshold and such that stress at a centerline of the tape
material during sintering remains below a centerline stress
threshold, where the edge stress threshold and the centerline
stress threshold are defined as those stresses above which the tape
material experiences out of plane deformation at the edge and
centerline, respectively, of greater than 1 mm, such as where the
edge stress threshold is less than 300 MPa and the centerline
stress threshold is less than 100 MPa. In at least some such
embodiments, the channel of the sintering station is at least 1 m
long. In at least some such embodiments, the sintering station
comprises (2d-i) a first sintering furnace defining a first portion
of the sintering station channel extending from the entrance of the
sintering station to an exit opening of the first sintering
furnace, (2d-ii) a second sintering furnace defining a second
portion of the sintering station channel extending from an entrance
opening of the second sintering furnace to the exit of the
sintering station, and (2e) a tension control system located
between the first sintering furnace and the second sintering
furnace, the tension control system helping to isolate tension
between the first and second sintering furnaces, wherein tension in
the tape material within the second sintering furnace that is
greater than a tension within the tape material in the first
sintering furnace. In at least some such embodiments, the sintering
station comprises (2f) an upward facing channel surface defining a
lower surface of the channel and (2g) a downward facing channel
surface defining an upper surface of the channel, where a lower
surface of the tape material is in contact with and slides along
the upward facing surface as the tape material moves from the
entrance to the exit of the sintering station, where the downward
facing channel surface is positioned close to an upper surface of
the tape material such that a gap between the upper surface of the
tape material and the downward facing channel surface is less than
0.5 inches, where at least a portion of the upward facing channel
surface is substantially horizontal measured in the direction
between the entrance and exit of the sintering station such that
the portion of the upward facing channel surface forms an angle of
less than 3 degrees relative to the horizontal plane. In at least
some such embodiments, the inorganic material of the tape is at
least one of a polycrystalline ceramic material and synthetic
mineral.
[0460] Aspects of the present disclosure include a manufacturing
furnace comprising (1) a housing having an upstream face and a
downstream face, (2) an entrance opening formed in the upstream
face, (3) an exit opening defined in the downstream face, (4) an
upward facing surface located between the entrance opening and the
exit opening, (5) a downward facing flat surface located between
the entrance opening and the exit opening, (6) a heating channel
extending between the entrance opening and the exit opening and
defined between the upward facing surface and the downward facing
surface, (7) a continuous length of tape extending into the
entrance opening, through the heating channel and out of the exit
opening, the continuous length of tape comprising: (7a) grains of
inorganic material, (7b) a left edge extending through the heating
channel the entire distance between the entrance opening and the
exit opening, (7c) a right edge extending through the heating
channel the entire distance between the entrance opening and the
exit opening, and (7d) a centerline parallel to and located between
the left edge and the right edge; and (8) a plurality of the
independently controlled heating elements delivering heat to the
heating channel generating a temperature profile along the length
of the heating channel, the temperature profile having temperatures
greater than 500 degrees C. sufficient to cause shrinkage of the
inorganic material of the tape as the tape moves through the
heating channel, where the temperature profile increases gradually
along at least a portion of the length of the heating channel such
that the stress within the tape during shrinkage at the left and
right edge remain below an edge stress threshold along the entire
length of the heating channel or stress within the tape material
measured at the centerline remain below a centerline stress
threshold along the entire length of the heating channel. In at
least some such embodiments, the edge stress threshold is less than
100 MPa and the centerline stress threshold is less than 100 MPa.
In at least some such embodiments, the continuous length of tape
has an average width greater than 5 mm. In at least some such
embodiments, the entrance opening and the exit opening are aligned
with each other in the vertical direction such that a straight line
located along the upward facing surface forms an angle relative to
a horizontal plane that is less than 10 degrees. In at least some
such embodiments, the continuous length of tape moves in a
direction from the entrance to the exit and the lower surface of
the tape moves relative to the upward facing surface, such as where
the lower surface of the tape is in contact with and slides
relative to the upward facing surface. In at least some such
embodiments, the temperature profile includes a first section
having a first average slope, a second section having second
average slope and a third section have a third average slope, where
the first average slope is greater than the second average slope,
and where the first and second average slopes are positive slopes
and the third average slope is a negative slope, such as where the
first, second and third sections are directly adjacent with one
another and in numerical order, and most or all of the temperature
profile; for example, in at least some such embodiments, the second
section has a minimum temperature that is greater than 500 degrees
C. and a maximum temperature that is less than 3200 degrees C., and
extends from the minimum temperature to the maximum temperature
over a length of at least 50 inches. In at least some such
embodiments, the heating channel is narrow, such that at a
cross-section along the length thereof the maximum vertical
distance between the upward facing surface and the downward facing
surface is less than one inch. In at least some such embodiments,
the heating channel is divided into at least a first heating
section and second heating section, where a tension control system
is located between the first heating section and the second heating
section, where the tension control system at least in part isolates
tension in the tape such that tension in the tape material within
the second heating section that is greater than tension within the
tape material in the first heating section. In at least some such
embodiments, the inorganic material of the tape is at least one of
a polycrystalline ceramic material and synthetic mineral.
[0461] Aspects of the present disclosure relate to a process for
forming a spool of sintered tape material comprising steps, not
necessarily in the following order, of (1) unwinding a tape from an
input reel, the tape comprising grains of inorganic material and a
width greater than 5 mm, (2) moving the unwound length of tape
through a heating station, (3) heating the tape within the heating
station to a temperature above 500 degrees C. such that the
inorganic material of the tape is sintered as it moves through the
heating station, and (4) winding the tape on an uptake reel
following heating and sintering. In at least some such embodiments,
the tape material is held in a substantially horizontal position
during heating. In at least some such embodiments, the tape
material on the input reel further comprises an organic binder
material supporting the grains of inorganic material, the process
further comprising heating the tape material to a temperature
between 200 degrees C. and 500 degrees C. to remove the binder
material before the step of heating the tape material to a
temperature above 500 degrees C. In at least some such embodiments,
the width of tape material is greater than 10 mm and the length of
the tape material is greater than 10 m. In at least some such
embodiments, the tape material is unwound at a speed of at least 6
inches per minute. In at least some such embodiments, the inorganic
material is at least one of a polycrystalline ceramic material and
synthetic mineral.
[0462] Aspects of the present disclosure relate to a manufacturing
system that comprises a tape advancing through the manufacturing
system, the tape including a first portion having grains of an
inorganic material bound by an organic binder; and a station of the
manufacturing system that receives the first portion of the tape
and prepares the tape for sintering by chemically changing the
organic binder and/or removing the organic binder from the first
portion of the tape, leaving the grains of the inorganic material,
to form a second portion of the tape and thereby at least in part
prepare the tape for sintering. In at least some such embodiments,
at an instant, the tape simultaneously extends to, through, and
from the station such that at the instant the tape includes the
first portion continuously connected to the second portion. In at
least some such embodiments, the station chars or burns at least
most of the organic binder, in terms of weight, from the first
portion of the tape without substantially sintering the grains of
the inorganic material. In at least some such embodiments, the
station comprises an active heater to char or burn at least most of
the organic binder from the first portion of the tape as the tape
interfaces with the station to form the second portion of the tape,
such as where the active heater includes heating zones of different
temperatures, such as where the rate of heat energy received by the
tape increases as the tape advances through the station. In at
least some such embodiments, the station is a first station and the
manufacturing system further comprises a second station, where the
second station at least partially sinters the inorganic material of
the second portion of the tape to form a third portion of the tape,
such as where, at an instant, the tape includes the first portion
continuously connected to the third portion byway of the second
portion, and/or such as where the first station is close to the
second station such that distance between the first and second
stations is less than 10 m, thereby mitigating thermal shock of the
second portion of the tape. In at least some such embodiments, the
second portion of the tape is under positive lengthwise tension as
the tape advances, such as where the lengthwise tension in the
second portion of the tape is less than 500 grams-force per
mm.sup.2 of cross section. In at least some such embodiments, the
manufacturing system blows and/or draws gas over the tape as the
tape advances through the station, such as where the station heats
the tape above a temperature at which the organic binder would
ignite without the gas blown and/or drawn over the tape, whereby
the organic binder chars or burns but the tape does not catch fire,
and/or such as where flow of the gas blown and/or drawn over the
tape as the tape advances through the station is laminar at least
over the second portion of the tape. In at least some such
embodiments, the tape advances horizontally through the station,
and in some such embodiments the tape is directly supported by a
gas bearing and/or an underlying surface and moves relative to that
surface as the tape advances through the station. In at least some
such embodiments, the first portion of the tape is substantially
more bendable than the second portion such that a minimum bend
radius without fracture of the first portion is less than half that
of the second portion.
[0463] Aspects of the present technology relate to a furnace to
prepare green tape for sintering the furnace comprising walls
defining a passage having inlet and outlet openings on opposing
ends of the passage, where the passage has a length between the
inlet and outlet openings of at least 5 cm, and where the outlet
opening is narrow and elongate, having a height and a width
orthogonal to the height, wherein the height is less than a fifth
of the width, and wherein the height is less than 2 cm; and the
furnace further includes a heater that actively provides heat
energy to the passage, where the heater reaches temperatures of at
least 200.degree. C. In at least some such embodiments, the furnace
is further comprising a gas motivator that blows and/or draws gas
through the passage, such as where the gas motivator delivers at
least 1 liter of gas per minute through the passage. In at least
some such embodiments, the passage is horizontally oriented, as
described above. In at least some such embodiments, the heater
comprises heat zones that increase temperature along the passage
with distance from the inlet toward the outlet.
[0464] Aspects of the present technology relate to a method of
processing tape, comprising steps of (1) advancing a tape through a
manufacturing system, the tape including a first portion having
grains of an inorganic material bound by an organic binder; and (2)
preparing the tape for sintering by forming a second portion of the
tape at a station of the manufacturing system by chemically
changing the organic binder and/or removing the organic binder from
the first portion of the tape, leaving the grains of the inorganic
material. In at least some such embodiments, at an instant, the
tape extends to, through, and from the station such that at the
instant the tape includes the first portion continuously connected
to the second portion. In at least some such embodiments, the step
of preparing the tape for sintering further comprises charring or
burning at least most of the organic binder from the first portion
of the tape without (substantially) sintering the grains of the
inorganic material. In at least some such embodiments, the first
portion of the tape is substantially more bendable than the second
portion such that a minimum bend radius without fracture of the
first portion is less than half that of the second portion. In at
least some such embodiments, the station of the manufacturing
system is a first station and the method of processing further
comprises steps of receiving the second portion of the tape at a
second station, and at least partially sintering the inorganic
material of the second portion of the tape at the second station to
form a third portion of the tape, such as in at least some such
embodiments, at an instant, the tape includes the first portion
continuously connected to the third portion by way of the second
portion. In at least some such embodiments, the process further
comprises a step of positively tensioning the second portion of the
tape as the tape advances, such as where the step of positively
tensioning is such that lengthwise tension in the second portion of
the tape is less than 500 grams-force per mm.sup.2 of cross
section. In at least some such embodiments, the process further
comprises a step of blowing and/or drawing gas over the tape as the
tape advances through the station. In at least some such
embodiments, the step of advancing the tape further comprises
horizontally advancing the tape through the station. In at least
some such embodiments, the process further comprises a step of
directly supporting the tape by a gas bearing and/or an underlying
surface and moving the tape relative to that surface.
[0465] Aspects of the present disclosure relate to package
comprising: a substrate; a sintered article comprising a body
extending between a first major surface and a second major
surface;
[0466] the body comprises a sintered inorganic material, a
thickness (t) defined as a distance between the first major surface
and the second major surface, a width defined as a first dimension
of one of the first or second surfaces orthogonal to the thickness,
and a length defined as a second dimension of one of the first or
second surfaces orthogonal to both the thickness and the width; and
the sintered article joined directly or indirectly to the
substrate. In some such embodiments, the body width is about 5 mm
or greater, the body thickness is in a range from about 3 .mu.m to
about 1 mm, and the body length is about 300 cm or greater. In some
such embodiments, the a portion of the sintered article is
flattenable, such as where the sintered article, when flattened,
exhibits a maximum in plane stress (the absolute value of stress,
as measured by the thin plate bend bending equation) of less than
or equal to 25% of the bend strength (measured by 2-point bend
strength) of the article and/or such as where the sintered article,
when flattened, exhibits a maximum in plane stress (the absolute
value of stress, as measured by the thin plate bend bending
equation) of less than or equal to 1% of the Young's modulus of the
article. In some such embodiments, the sintered article has a
thickness of about 80 .mu.m and a bend radius of greater than 0.03
m, the article exhibits a maximum in plane stress (the absolute
value of stress, as measured by the thin plate bend bending
equation) of less than or equal to 25% of the bend strength
(measured by 2-point bend strength) of the article; or the sintered
article has a thickness of about 40 .mu.m and a bend radius of
greater than 0.015 m, the article exhibits a maximum in plane
stress (the absolute value of stress, as measured by the thin plate
bend bending equation) of less than or equal to 25% of the bend
strength (measured by 2-point bend strength) of the article; or the
sintered article has a thickness of about 20 .mu.m and a bend
radius of greater than 0.0075 m, the article exhibits a maximum in
plane stress (the absolute value of stress, as measured by the thin
plate bend bending equation) of less than or equal to 25% of the
bend strength (measured by 2-point bend strength) of the article.
In some such embodiments, a portion of the sintered article that is
flattenable comprises a length of about 10 cm. In some such
embodiments, one or both the first major surface and the second
major surface of the sintered article has a flatness in the range
of one hundred nanometers to fifty micrometers over a distance of
one centimeter along the length or the width. In some such
embodiments, the sintered inorganic material comprises an interface
having a major interface dimension of less than about 1 mm, wherein
the interface comprises either one of or both a chemical
inhomogeneity and crystal structure inhomogeneity. In some such
embodiments, the sintered inorganic material comprises a ceramic
material or a glass ceramic material. In some such embodiments, the
sintered inorganic material comprises any one of a piezoelectric
material, a thermoelectric material, a pyroelectric material, a
variable resistance material, or an optoelectric material. In some
such embodiments, the sintered inorganic material comprises one of
zirconia, alumina, yttria stabilized zirconia (YSZ), spinel,
garnet, lithium lanthanum zirconium oxide (LLZO), cordierite,
mullite, perovskite, pyrochlore, silicon carbide, silicon nitride,
boron carbide, sodium bismuth titanate, barium titanate, titanium
diboride, silicon alumina nitride, aluminum oxynitride, or a
reactive cerammed glass-ceramic. In some such embodiments, the
sintered article comprises at least ten square centimeters of area
along the length that has a composition wherein at least one
constituent of the composition varies by less than about 3 weight %
across the area. In some such embodiments, the sintered article
comprises at least ten square centimeters of area along the length
that has a crystalline structure with at least one phase having a
weight percent that varies by less than about 5 percentage points,
across the area. In some such embodiments, the sintered article
comprises at least ten square centimeters of area along the length
that has a porosity varies by less than about 20%. In some such
embodiments, the one or both the first major surface and the second
major surface of the sintered article has a granular profile
comprising grains with a height in a range from 25 nm to 150 .mu.m
relative to recessed portions of the respective surface at
boundaries between the grains. In some such embodiments, the one or
both the first major surface and the second major surface of the
sintered article has a flatness in the range of 100 nm to 50 .mu.m
over a distance of one centimeter along the length or the width. In
some such embodiments, the one of or both the first major surface
and the second major surface of the sintered article comprises have
at least ten square centimeters of area having fewer than one
hundred surface defects from adhesion or abrasion with a dimension
greater than 5 .mu.m. In some such embodiments, the other of the
first major surface and the second major surface of the sintered
article comprises surface defects from adhesion or abrasions with a
dimension of greater than 5 .mu.m, such as due to sliding along a
surface of the furnace during sintering. In some such embodiments,
the substrate comprises an electrically conductive metal. In some
such embodiments, the substrate comprises aluminum, copper, or
combinations thereof. In some such embodiments, the substrate
comprises a compliant polymer material. In some such embodiments,
the substrate comprises a polyimide. In some such embodiments, the
sintered article joined directly or indirectly to the substrate is
rolled around a core at least once, the core having a diameter of
less than 60 cm. In some such embodiments, the package is further
comprising an interlayer that joins the sintered article and the
substrate, such as where the interlayer has a thickness less than
40 .mu.m and/or where the substrate comprises grooves that contact
the interlayer. In some such embodiments, the package is further
comprising a metal-based layer on at least a portion of one or both
the first major surface and the second major surface of the
sintered article, such as where the metal-based layer comprises
copper, nickel, gold, silver, gold, brass, lead, tin, or
combinations thereof and/or where the metal-based layer and the
substrate are joined to same major surface of the sintered article,
and/or where the metal-based layer is joined to the sintered
article through an aperture in the substrate. In some such
embodiments, the package is further comprising a semiconductor
device electrically connected to the metal-based layer, such as
where light that emanates from an LED on the semiconductor device
transmits through the body thickness of the sintered article,
and/or wherein the sintered article has a thermal conductivity
greater than 8 W/m K.
[0467] Additional aspects of the present disclosure relate to
method of making some or all of the packages just described, the
method comprising a step of joining the substrate directly or
indirectly to the first or second major surface of the sintered
article. In some such embodiments, the substrate comprises a
compliant polymer material. In some such embodiments, the substrate
comprises an electrically conductive metal. In some such
embodiments, the method further comprises applying a precursor
interlayer to one or both of the substrate and the sintered
article, the precursor interlayer joins the substrate and the
sintered article. In some such embodiments, the method further
comprises thermally deactivating the temporary adhesive to separate
the substrate from the sintered article. In some such embodiments,
the method further comprises bonding a metal-based layer on at
least a portion of one or both the first major surface and the
second major surface of the sintered article, and the method may
further comprise electrically connecting a semiconductor device to
the metal-based layer.
[0468] Aspects of the present disclosure relate to a process for
forming a sintered tape material comprising steps of (1) moving a
tape toward a heating station, the tape comprising grains of
inorganic material, (2) coupling a first section of a threading
material to a leading section of the tape, (3) pulling both the
first section of threading material and the leading section of the
tape through the heating station by applying a force to a second
section of the threading material located outside of the heating
station, and (4) heating at least a portion of the tape within the
heating station to a temperature above 500 degrees C. such that the
inorganic material of the tape is sintered as it moves through the
heating station. In some such embodiments, the heating station has
an entrance and an exit, and the process is further comprising a
step of positioning the threading material such that the threading
material extends through the heating station, that the first
section of the threading material is located upstream from the
entrance and that a second section of threading material is located
downstream from the exit, where the coupling step occurs after the
positioning step. In some such embodiments, the threading material
is an elongate strip of material that is different from the
inorganic material of tape, such as where the difference between
the threading material and the inorganic material of tape is at
least one of a different material type and different degree of
sintering, and/or where the leading section of the tape overlaps
the first section of the threading material such that a lower
surface of the tape contacts an upper surface of the threading
material. In some such embodiments, the coupling step comprises
bonding the threading material to the tape via an adhesive
material, such as where a coefficient of thermal expansion of the
threading material is within plus or minus 50% of a coefficient of
thermal expansion of the inorganic material of the tape and is
within plus or minus 50% of a coefficient of thermal expansion of
the adhesive material, and/or where the inorganic material of the
tape is at least one of a polycrystalline ceramic material and
synthetic mineral, where the adhesive material is a ceramic
containing adhesive material, and where the threading material is
at least one of a sintered ceramic material and a metal material.
In some such embodiments, the step of moving the tape toward the
heating station includes unwinding the tape from an input reel,
where the second section of the threading material is coupled to an
uptake reel, and the force is generated by rotation of the uptake
reel. In some such embodiments, the process further comprises a
step of continuing to move the tape through a heating station
following unwinding from the input reel forming a length of
sintered inorganic material of the tape; and another step of
winding the tape on an uptake reel following heating and sintering,
such as where the tape is held in a substantially horizontal
position during heating, such as where the tape on the input reel
further comprises an organic binder material supporting the grains
of inorganic material, and the process further comprises heating
the tape to a temperature between 200 degrees C. and 500 degrees C.
to remove the binder material before the step of heating the tape
to a temperature above 500 degrees C.
[0469] Aspects of the present disclosure relate to a process for
forming a spool of sintered tape material comprising steps of (1)
unwinding a tape from an input reel, the tape comprising grains of
inorganic material; (2) moving a threading material through a
channel of a heating station in a direction from an exit of the
heating station toward an entrance of the heating station such that
a first section of a threading material extends out of the entrance
of the heating station; (3) coupling the first section of the
threading material to the tape; (4) coupling a second section of
the threading material to an uptake reel located downstream from
the exit of the heating station; (5) rotating the uptake reel such
that tension is applied to the threading material by the uptake
reel which in turn is applied to the tape pulling the tape through
the heating station; (6) heating at least a portion of the tape
within the heating station to a temperature above 500 degrees C.
such that the inorganic material of the tape is sintered as it
moves through the heating station; and (7) winding the tape on an
uptake reel following heating and sintering. In some such
embodiments, at least one of: (i) the threading material and the
inorganic material of tape are different from each other and (ii) a
degree of sintering of the threading material is greater than a
degree of sintering of the inorganic material of the tape on the
input reel. In some such embodiments, the leading section of the
tape overlaps the first section of the threading material such that
a lower surface of the tape contacts an upper surface of the
threading material, and the coupling step comprises bonding the
threading material to the tape via an adhesive material.
[0470] Aspects of the present technology relate to a roll to roll
tape sintering system comprising (1) an input roll of a length of
tape material comprising grains of inorganic material, the
inorganic material of the tape material on the input roll having a
first porosity; (2) a sintering station comprising: (2a) an
entrance; (2b) an exit; (2c) a channel extending between the
entrance and the exit; and (2d) a heater heating the channel to a
temperature greater than 500 degrees C., where wherein the tape
material extends from the input roll toward the entrance of the
sintering station, where heat within the channel causes sintering
of the inorganic material of the tape material; (3) an uptake roll
winding the length of tape material following exit from the
sintering station; and (4) a length of threading material extending
through the exit and out of the entrance of the sintering station,
wherein a first end section of the threading material is coupled to
a leading section of the tape material before the entrance of the
sintering station and a second end section of the threading
material is wrapped around the uptake roll such that tension
applied to the threading material by winding of the uptake roll is
applied to the tape material. In some such embodiments, at least
one of: (i) the threading material and the inorganic material of
tape material are different from each other and (ii) a degree of
sintering of the threading material is greater than a degree of
sintering of the inorganic material of the tape on the input roll.
In some such embodiments, the leading section of the tape material
overlaps the first section of the threading material such that a
lower surface of the tape material contacts an upper surface of the
threading material, and the threading material is coupled to the
tape material via a bond formed by an adhesive material, such as
where the inorganic material is at least one of a polycrystalline
ceramic material and synthetic mineral, where the adhesive material
is a ceramic adhesive material, and where the threading material is
at least one of a sintered ceramic material and a metal material.
In some such embodiments, the exit, the entrance and the channel of
the sintering station lie in a substantially horizontal plane, such
that an angle defined between the exit and the entrance relative to
a horizontal plane is less than 10 degrees.
[0471] Aspects of the present disclosure relate to a process for
forming a sintered tape material comprising steps of (1) unwinding
a tape from an input reel, the tape comprising grains of inorganic
material, wherein the tape on the input reel has an average
thickness between 1 micron and 1 millimeter; (2) moving the unwound
length of tape through a heating station along a path having a
first curved section such that the tape is bent through a radius of
curvature of 0.01 m to 13,000 m; (3) heating the tape within the
heating station to a temperature above 500 degrees C. while the
unwound length of tape is bent through the radius of curvature,
wherein the inorganic material of the tape is sintered as it moves
through the heating station; and (4) winding the tape on a take-up
reel following heating and sintering. In contemplated embodiments,
such a process may be broader, and may not include the unwinding
and/or the winding steps. In some such embodiments, the heating
station includes a lower surface and an upper surface defining a
channel extending between an entrance and an exit of the heating
station, where the lower surface includes a convex curved surface
extending in a longitudinal direction between the entrance and the
exit, wherein the convex curved surface defines the first curved
section of the path. In some such embodiments, the upper surface
includes a concave curved surface matching the convex curved
surface of the lower surface such that a height of the channel
remains constant along at least a portion of a length of the
channel. In some such embodiments, the convex curved surface is an
upper surface of a gas bearing, and the gas bearing delivers
pressurized gas to the channel to support the tape above the convex
curved surface as the tape moves through the heating station. In
some such embodiments, the convex curved surface is continuous
curved surface the extends an entire longitudinal length between
the entrance and the exit, wherein a maximum rise of the convex
curved surface is between 1 mm and 10 cm. In some such embodiments,
the path through the heating station has a second curved section
having a radius of curvature of 0.01 m to 13,000 m, where the tape
is heated within the heating station to a temperature above 500
degrees C. while the unwound length of tape is bent through the
radius of curvature of the second curved section, such as where the
tape is heated to a first temperature when the tape traverses the
first curved section and is heated to a second temperature,
different from the first temperature, when the tape traverses the
second curved section. In some such embodiments, the first curved
section of the path is defined by a free loop segment in which the
tape hangs under the force of gravity between a pair of supports to
form the radius of curvature in the tape. In some such embodiments,
the heating station has a convex curved surface located therein
defining the first curved section of the path, and the process
further comprises a step of applying tension to the tape such that
the tape bends into conformity with the convex curved surface, such
as where the convex curved surface is an outer surface of at least
one of a mandrel and a roller. In some such embodiments, the tape
is moved through the heating station at a speed of between 1 inch
and 100 inches of tape length per minute. In some such embodiments,
tension is applied to the tape in a longitudinal direction, where
the tape has a width and the tension is at least 0.1 gram-force per
linear inch of width of the tape. In some such embodiments, the
inorganic material of the tape is at least one of a polycrystalline
ceramic material and synthetic mineral.
[0472] Aspects of the present disclosure relate to a process for
forming a sintered tape material comprising steps of (1) moving a
contiguous length of tape through a heating station such that a
first portion of the contiguous length of tape is located upstream
from an entrance of the heating station, a second portion of the
contiguous length of tape is located downstream from an exit of the
heating station, and a third portion of the contiguous length of
tape is located between the first portion and the second portion,
the contiguous length of tape comprising grains of inorganic
material, (2) heating the third portion of the contiguous length of
tape within the heating station to a temperature above 500 degrees
C. such that the inorganic material is sintered within the heating
station, and (3) bending the third portion of the contiguous length
of tape to a radius of curvature of 0.01 m to 13,000 m while at the
temperature above 500 degrees C. within the heating station. In at
least some such embodiments, the bending includes applying a
longitudinally directed force to the contiguous length of tape such
that third portion bends around a curved surface located within the
heating station. In at least some embodiments, the contiguous
length of tape is unrolled from an input reel, the contiguous
length of tape is moved continuously and sequentially through the
heating station such that entire contiguous length of the tape
experiences bending to the radius of curvature of 0.01 m to 13,000
m while moving through the heating station, and where the
contiguous length of tape is rolled onto a take-up reel following
bending and heating.
[0473] Aspects of the present disclosure relate to a roll-to-roll
tape sintering system comprising (1) an input roll of a length of
tape material comprising grains of inorganic material, the
inorganic material of the tape material on the input roll having a
first porosity; (2) a sintering station comprising: (2a) an
entrance; (2b) an exit; (2c) a channel extending between the
entrance and the exit; (2d) a heater heating the channel to a
temperature greater than 500 degrees C.; where the tape material
passes from the input roll, into the entrance of the sintering
station, through the channel of the sintering station and out of
the exit of the sintering station and the heat within the channel
causes sintering of the inorganic material of the tape material;
(3) a bending system located within the sintering station inducing
a radius of curvature along a longitudinal axis of the tape
material as the tape material passes through the heating station,
wherein the radius of curvature is 0.01 m to 13,000 m; and (4) a
take-up roll winding the length of tape material following exit
from the sintering station; where the inorganic material of the
tape material on the take-up roll has a second porosity that is
less than the first porosity. In some such embodiments, the exit
and the entrance lie in a substantially horizontal plane such that
an angle defined between the exit and the entrance relative to a
horizontal plane is less than 10 degrees, wherein the bending
system includes a convex curved surface located along a path
between the entrance and the exit, wherein the tape is bent around
the convex curved surface as the tape moves through the heating
station, wherein the convex curved surface defines the radius of
curvature and is curved around an axis parallel to a width axis of
the tape material. In some such embodiments, the convex curved
surface is an outer surface of at least one of a mandrel and a
roller and/or the convex curved surface is a lower surface of the
sintering station that defines the channel of the sintering
station, such as where the convex curved surface forms a continuous
curve that extends the entire length of the channel from the
entrance to the exit of the sintering station. In some such
embodiments, the convex curved surface is an upper surface of a gas
bearing that delivers gas to the channel supporting the tape within
the channel without contacting the convex curved surface. In other
such embodiments, the bending system includes a pair of support
structures located with the sintering station, wherein the support
structures are spaced from each other forming a gap and the tape
sags downward due to gravity between the support structures to form
the radius of curvature.
[0474] Aspects of the present disclosure relate to a roll-to-roll
tape sintering system comprising (1) an input roll of a length of
tape material comprising grains of inorganic material, the
inorganic material of the tape material on the input roll having a
first porosity; (2) a sintering station comprising: (2a) an
entrance; (2b) an exit; (2c) a channel extending between the
entrance and the exit having a longitudinal length, L, wherein a
lower surface of the channel is defined by a continuously curved
surface extending the longitudinal length L and having a radius of
curvature, R, and a maximum rise, H; wherein R=H+(L{circumflex over
( )}2)/H; wherein 0.1 mm<H<100 mm, and 0.1 m<L2<100 m;
(3) a heater heating the channel to a temperature greater than 500
degrees C.; wherein the tape material passes from the input roll,
into the entrance of the sintering station, through the channel of
the sintering station and out of the exit of the sintering station
and the heat within the channel causes sintering of the inorganic
material of the tape material; and (4) a take-up roll winding the
length of tape material following exit from the sintering station,
wherein the inorganic material of the tape material on the take-up
roll has a second porosity that is less than the first
porosity.
[0475] Some aspects of the present disclosure relate to a tape
separation system for sintering preparation by separating parts of
the tape from one another, as disclosed above and discussed with
regard to FIGS. 3, 4, 6, 8 for example. More specifically, the tape
separation system includes a source of tape material (e.g.,
pre-made roll, pre-made long strip, in-line green tape
manufacturing) comprising a green tape and a carrier web (e.g., a
polymeric substrate) supporting the green tape. The green tape
comprising grains of inorganic material in a binder (e.g., organic
binder as disclosed above, and may further include inorganic
binder). The tape separation system further includes a peeler (see
FIG. 8) for directing the carrier web in a rewind direction and
directing the green tape in a downstream processing direction that
differs from the rewind direction, such as by angle C in FIG. 8;
and a vacuum drum positioned and configured to receive the tape
material from the source and convey the tape material to the
peeler. The vacuum drum comprises holes for applying suction to the
carrier web to facilitate tensioning the carrier web. For example,
suction of the vacuum drum applies attractive force to the tape
beyond the forces of gravity and friction. In alternative
embodiments, other sources of attractive force may be used, such as
magnetic forces acting on a magnetic carrier web, electrostatic
forces, etc., where the vacuum drum may be more broadly
characterized as an attractive drum. According to an exemplary
embodiment, tension, in force per cross-sectional area, in the
carrier web is greater than tension in the green tape as the tape
material is conveyed from the vacuum drum to the peeler, thereby
mitigating deformation of the green tape during separation of the
green tape from the carrier web. The carrier web bears the brunt of
force used to move and control the tape. Similarly the peeler with
the removal of carrier web acts to protect the shape of the green
tape, which in turn facilitates the particularly high quality
sintered article in terms of geometric consistency.
[0476] Other aspects of the present disclosure relate to a system
for processing tape for sintering preparation, as shown and
discussed with regard to FIGS. 9, 10, and 12 for example. The
system includes a tape comprising a green portion of the tape, the
green portion having grains of an inorganic material in an organic
binder; and a binder burnout station comprising an active heater.
The tape advances through the binder burnout station such that the
binder burnout station receives the green portion of the tape and
chars or burns the organic binder as the green portion of the tape
interfaces with heat from the heater, thereby forming a second
portion of the tape prepared for sintering the inorganic material
of the tape. In some embodiments, at an instant, the tape
simultaneously extends to, through, and from the binder burnout
station such that, at the instant, the tape includes the green
portion continuously connected to the second portion, such as where
the binder burnout station chars or burns at least most of the
organic binder, in terms of weight, from the green portion of the
tape without substantially sintering the grains of the inorganic
material. Such a system may be particularly surprising to those of
skill in the art because of perceived weakness of the tape with the
organic binder removed or charred, and with associated changes in
dimensions of the tape during such processing. In some embodiments,
system for processing tape for sintering preparation further
includes an ultra-low tension dancer that includes light-weight,
low-inertia rollers to redirect the tape without exerting
significant tension such that tension in the second portion of the
tape is less than 500 grams-force per mm.sup.2 of cross section,
thereby reducing chances of fracture of the second portion of the
tape and facilitating long continuous lengths of the tape for
sintering. In some embodiments, system for processing tape for
sintering preparation blows and/or draws gas over the tape as the
tape advances through the binder burnout station, and the binder
burnout station heats the tape above a temperature at which the
organic binder would ignite without the gas blown and/or drawn over
the tape, whereby the organic binder chars or burns but the tape
does not catch fire.
[0477] Additional aspects of the present disclosure relate to a
manufacturing line comprising the above system for processing tape,
where the binder burnout station is a first station and the
manufacturing line further comprises a second station spaced apart
from the first station. The second station may be spaced apart from
the first station as shown in FIG. 12, and/or there may be a common
housing and separation may be due to an intermediate ventilation
system that controls air flow relative to the two stations for
example. The second station at least partially sinters the
inorganic material of the second portion of the tape to form a
third portion of the tape, where, at an instant, the tape includes
the green portion continuously connected to the third portion by
way of the second portion. In some embodiments, the third portion
of the tape is substantially more bendable than the second portion
such that a minimum bend radius without fracture of the third
portion is less than half that of the second portion, and the green
portion is substantially more bendable than the second portion such
that a minimum bend radius without fracture of the green portion is
less than half that of the second portion. In other embodiments,
the tape or other article may not comprise three different such
portions, such as if only shorter lengths of articles were
processed using the sintering system. The manufacturing line may
further include the tape separation system described above, such as
with the peeler and vacuum drum.
[0478] Some aspects of the present disclosure relate to a sintering
system comprising a tape material comprising grains of inorganic
material and a sintering station, such as discussed above with
regard to FIG. 3 for example. The sintering station includes an
entrance, an exit, and a channel extending between the entrance and
the exit. At an instant, the tape material extends into the
entrance of the sintering station, through the channel, and out of
the exit. Heat within the channel sinters the inorganic material
such that the inorganic material has a first porosity at the
entrance and a second porosity at the exit that is less than the
first porosity, such as at least 10% less by volume. Further, the
wherein the tape material is positively tensioned as the tape
material passes through the channel of the sintering station,
thereby mitigating warpage, such as by tension applied via the
low-tension dancer, by reel winding/unwinding, directional air
bearings, variation in roller speed, or other components of the
system to positively apply tension to the tape material beyond
gravitational and frictional forces. In some embodiments, the tape
material moves through the sintering station at a speed of at least
1 inch per minute, such as at least 10, at least 20, at least 40
inches per minute. For discrete articles, as opposed to long tapes
as disclosed herein, the articles may stop or dwell within the
sintering station, or may move different speeds. In some
embodiments, the channel of the sintering station is heated by at
least two independently controlled heating elements, where the
heating elements generate a temperature profile where the channel
increases in temperature along the length of the channel in a
direction from the entrance toward the exit of the sintering
station, and where a sintering temperature in the channel exceeds
800.degree. C. (see, e.g., FIG. 19 and related discussion above).
In some embodiments, the sintering system further includes a curved
surface located along the channel of the sintering station (see,
e.g., FIG. 58 and related discussion above), where the tape
material bends relative to a widthwise axis of the tape material
around the curved surface as the tape material moves through the
sintering station, thereby influencing shape of the tape material,
such as flattening the tape material and/or preventing bulges or
other distortions (see, e.g., FIG. 1). In some embodiments, the
exit and the entrance of the sintering station lie in a
substantially horizontal plane, such that an angle defined between
the exit and the entrance of the sintering station relative to a
horizontal plane is less than 10 degrees, thereby at least in part
controlling flow of gases relative to the channel. Applicants have
found that, alternatively or in addition thereto, flow of gasses
may be controlled by vents and fans and/or by confining the tape in
a narrow space. For example, in some such embodiments, the
sintering station further comprises an upward facing channel
surface defining a lower surface of the channel, and a downward
facing channel surface defining an upper surface of the channel,
where the downward facing channel surface is positioned close to an
upper surface of the tape material such that a gap between the
upper surface of the tape material and the downward facing channel
surface is less than 0.5 inches, thereby at least in part
controlling flow of gases in the channel. The tape material may be
particularly wide, long, and thin, having a width greater than 5
millimeters, a length greater than 30 centimeters, and a thickness
between 3 micrometers and 1 millimeter, and the inorganic material
of the tape may be at least one of a polycrystalline ceramic
material and synthetic mineral. In other embodiments, the tape or
other article may be narrower, shorter, and/or thicker, but
sintering may not be efficient in terms of sintering time/energy
cost, the tape may not roll and/or flatten as disclosed above,
etc.
[0479] Other aspects of the present disclosure relate to a process
for manufacturing ceramic tape, the process comprising a step of
sintering tape comprising polycrystalline ceramic to a porosity of
the polycrystalline ceramic of less than 20% by volume, by exposing
particles of the polycrystalline ceramic to a heat source to induce
the sintering between the particles. The tape is particularly thin
such that a thickness of the tape is less than 500 .mu.m, thereby
facilitating rapid sintering via heat penetration. Further, the
tape is at least 5 mm wide and at least 300 cm long. In some
embodiments, the process further includes a step of positively
lengthwise tensioning the tape during the sintering. In some such
embodiments, the process further includes a step of moving the tape
toward and then away from the heat source during the sintering,
such as through the channel of the sintering station. In some
embodiments, the amount of time of the sintering is particularly
short, that being less than two hours in aggregate for any
particular portion of the tape, thereby helping to maintain small
grain size in the ceramic tape, improving strength, reducing
porosity, saving energy; for example, in some such embodiments, the
time in aggregate of the sintering is less than one hour, such as
compared to 20 hour for conventional batch sintering, and density
of the polycrystalline ceramic after the sintering is greater than
95% dense by volume and/or the tape comprises closed pores after
the sintering, no pin holes, few surface defects, geometric
consistency, etc. In some embodiments, the tape comprises a
volatile constituent that vaporizes during the sintering, such as
lithium, where the volatile constituent is inorganic, and where the
tape comprises at least 1% by volume (e.g., at least 5%, at least
10%, and/or no more than 200%, such as no more than 100% by volume)
more of the volatile constituent prior to the sintering than after
the sintering. While some of the volatile constituent may vaporize,
Applicants believe that the present sintering technology is far
more efficient than conventional processes that use sealed
crucibles that surround the sintering material in sand containing
the volatile constituent to prevent release of the volatile
constituent through high vapor pressures. Applicants have
discovered that speed of sintering and geometry of the article may
be used to rapidly sinter such volatile materials before too much
of the volatile constituent escapes, and a source of excess
volatile constituent can be added to green tape, as disclosed
above, to greatly improve properties of the resulting sintered
article, such as in terms of percentage of cubic crystals, small
grain size, less porosity, and greater ionic conductivity,
hermeticity, strength, etc.
[0480] Still other aspects of the present disclosure relate to a
tape (see FIGS. 67A, 67B, 68, 69, for example, and related
discussion; see also FIGS. 29 and 78 and related discussion above)
or other article (e.g., sheet) comprising a body comprising grains
of inorganic material (ceramic, glass-ceramic, glass, metal)
sintered to one another, such as where atoms in particles of the
inorganic material diffuse across boundaries of the particles,
fusing the particles together and creating one solid piece, such as
without fully melting the particles to liquid state. With that
said, embodiments include articles of amorphous or nearly amorphous
material (e.g., FIG. 81). The body extending between first and
second major surfaces, where the body has a thickness defined as
distance between the first and second major surfaces, a width
defined as a first dimension of the first major surface orthogonal
to the thickness, and a length defined as a second dimension of the
first major surface orthogonal to both the thickness and the width.
The tape is long, having a length of about 300 cm or greater. The
tape is thin, having a thickness in a range from about 3 .mu.m to
about 1 mm. The tape is particularly wide, having a width of about
5 mm or greater. In other embodiments, the tape or other article
may have other dimensions, as disclosed herein.
[0481] According to an exemplary embodiment, geometric consistency
of the tape is such that a difference in width of the tape, when
measured at locations lengthwise separated by a distance, such as
10 cm, 50 cm, 1 m, 2 m, 10 m is less than a small amount, such as
less than 200 .mu.m, less than 100 .mu.m, less than 50 .mu.m, less
than 10 .mu.m; and/or a difference in thickness of the tape, when
measured at locations lengthwise separated by a distance, such as
10 cm, 50 cm, 1 m, 2 m, 10 m along a widthwise center of the tape
(i.e. along the centerline extending the length of the tape), is
less than a small amount, such as less than 50 .mu.m, less than 20
.mu.m, less than 10 .mu.m, less than 5 .mu.m, less than 3 .mu.m,
less than 1 .mu.m in some such embodiments. Laser trimming may help
improve the geometric consistency of the width of the tape. A layer
(e.g., silica, a material with melting temperature above
500.degree. C., above 800.degree. C., above 1000.degree. C.), as
shown in FIG. 103 overlaying the granular profile, may improve
geometric consistency of the thickness and/or may be polished or
provide an alternative to polishing.
[0482] In some embodiments, the tape is flat or flattenable, as
described above, such that a length of 10 cm of the tape pressed
between parallel flat surfaces flattens to contact or to within
0.25 mm of contact with the parallel flat surfaces, such as within
0.10 mm, such as within 0.05 mm, such as within 0.03 mm, such as
within 0.01 mm, without fracturing; and for example in some such
embodiments, when flattened to within 0.05 mm of contact with the
parallel flat surfaces, the tape exhibits a maximum in plane stress
of no more than 10% of the Young's modulus thereof, such as no more
than 5% of the Young's modulus thereof, such as no more than 2% of
the Young's modulus thereof, such as no more than 1% of the Young's
modulus thereof, such no more than 0.5% of the Young's modulus
thereof. In some embodiments, the first and second major surfaces
of the tape have a granular profile, such as where the grains are
ceramic (see FIG. 30B and related discussion, for example), and
where at least some individual grains of the ceramic adjoin one
another with little to no intermediate amorphous material such that
a thickness of amorphous material between two adjoining grains is
less than 50 nm, such as less than 10 nm, such as less than 5 nm,
such as less than 2 nm, such as where crystal lattices of adjoining
grains directly abut one another, as viewed by transition electron
microscopy for example (see, e.g., FIGS. 73C, 74, 75 and related
discussion).
[0483] In some embodiments, the body has less than 10% porosity by
volume and/or the body has closed pores, as shown in FIGS. 86B,
99B, 102 for example. In some embodiments, the grains comprise
lithium and/or another volatile constituent, and the body has ionic
conductivity of greater than 5.times.10.sup.-5 S/cm, such as ionic
conductivity of greater than 1.times.10.sup.-4 S/cm, such as ionic
conductivity of greater than 2.times.10.sup.-4 S/cm, such as ionic
conductivity of greater than 3.times.10.sup.-4 S/cm. In some
embodiments, the body has a particularly fine grain size (average),
that being 15 .mu.m or less, such as 10 .mu.m or less, such as 5
.mu.m or less, such as 2 .mu.m or less, as measured by ASTM
standard, as described above.
[0484] In some embodiments, the tape further includes an
electrically-conductive metal coupled to the first major surface of
the body, where in some such embodiments the body comprises a
repeating pattern of vias, and the electrically-conductive metal is
arranged in a repeating pattern (see generally FIGS. 51 and 104).
In some embodiments, the first and second major surfaces have a
granular profile, the tape further includes a coating overlaying
the granular profile of the first major surface, and an outward
facing surface of the coating is less rough than the granular
profile of the first surface, such as by at least half (see, e.g.,
FIG. 103), where electrically-conductive metal coupled to the first
major surface is so coupled by way of bonding to the outward facing
surface of the coating. In some embodiments, the inorganic material
has viscosity of 12.5 poise at a temperature greater than
900.degree. C. (see, e.g., FIGS. 78 and 87).
[0485] Additional aspects of the present disclosure relate to a
roll of the tape of any one of the above-described embodiments
(see, e.g., FIGS. 67A, 67B, 68, 69), wherein the tape is wrapped
around and overlapping itself, such as in a spiral, bent to a
radius of less than 1 m, such as less than 30 cm, such as less than
20 cm, such as less than 10 cm. A core of the roll may be round in
cross-section, or otherwise shaped.
[0486] Still other aspects of the present disclosure relate to a
plurality of sheets cut from tape of any one of the above-described
embodiments (see, generally FIGS. 93, 104). According to an
exemplary embodiment, the sheets have a common attribute with one
another that is detectable to determine that the sheets were
manufactured using technology disclosed herein. For example, the
common attribute may be at least one of: (a) a commonly positioned
surface groove (b) a pattern of grooves in common; (c) a commonly
present stress profile irregularity extending lengthwise; (d) a
compositional incongruity in common, and (e) a common asymmetric
crystal phase distribution or common pattern in crystal
concentration.
[0487] Some aspects of the present disclosure relate to a tape,
comprising a body comprising ceramic grains sintered to one
another, the body extending between first and second major
surfaces, where the body has a thickness defined as distance
between the first and second major surfaces, a width defined as a
first dimension of the first major surface orthogonal to the
thickness, and a length defined as a second dimension of the first
major surface orthogonal to both the thickness and the width; where
the tape is thin, having a thickness in a range from about 3 .mu.m
to about 1 mm; and where first and second major surfaces of the
tape have a granular profile, and at least some individual grains
of the ceramic adjoin one another with little to no intermediate
amorphous material such that a thickness of amorphous material
between two adjoining grains is less than 5 nm.
[0488] Some aspects of the present disclosure relate to a tape or
other sintered article (e.g., fiber, tube, sheet, discs),
comprising a body comprising ceramic grains sintered to one
another, the body extending between first and second major
surfaces, where the body has a thickness defined as distance
between the first and second major surfaces, a width defined as a
first dimension of the first major surface orthogonal to the
thickness, and a length defined as a second dimension of the first
major surface orthogonal to both the thickness and the width; where
the tape is thin, having a thickness in a range from about 3 .mu.m
to about 1 mm; where first and second major surfaces of the tape
have a granular profile; and where the grains comprise lithium and
the body has ionic conductivity greater than 5.times.10.sup.-5 S/cm
or higher, as discussed above. Such an article may have a thickness
of amorphous material between two adjoining grains is less than 5
nm. In some embodiments, the article is at least 95% dense and has
a grain size of less than 10 .mu.m, such as at least 97% dense and
has a grain size of less than 5 .mu.m. The article may be co-fired
with an anode and/or cathode material as part of a solid state
battery, for example.
[0489] Unless otherwise expressly stated, it is in no way intended
that any method set forth herein be construed as requiring that its
steps be performed in a specific order. Accordingly, where a method
claim does not actually recite an order to be followed by its steps
or it is not otherwise specifically stated in the claims or
descriptions that the steps are to be limited to a specific order,
it is in no way intended that any particular order be inferred. In
addition, as used herein, the article "a" is intended to include
one or more component or element, and is not intended to be
construed as meaning only one. Similarly, pieces of equipment and
process steps disclosed herein may be used with materials other
than continuous tape. For example, while continuous tape may be
particularly efficient for roll-to-roll processing, Applicants have
demonstrated that a sled of zirconia or other refractory material
may be used to draw discrete sheets of material or other articles
through equipment disclosed herein.
[0490] It will be apparent to those skilled in the art that various
modifications and variations can be made without departing from the
spirit or scope of the disclosed embodiments. Since modifications,
combinations, sub-combinations and variations of the disclosed
embodiments incorporating the spirit and substance of the
embodiments may occur to persons skilled in the art, the disclosed
embodiments should be construed to include everything within the
scope of the appended claims and their equivalents.
* * * * *