U.S. patent application number 11/048737 was filed with the patent office on 2005-06-16 for method of manufacturing electronic component and member to be used in the same method.
This patent application is currently assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.. Invention is credited to Nakao, Keiichi.
Application Number | 20050126003 11/048737 |
Document ID | / |
Family ID | 18972151 |
Filed Date | 2005-06-16 |
United States Patent
Application |
20050126003 |
Kind Code |
A1 |
Nakao, Keiichi |
June 16, 2005 |
Method of manufacturing electronic component and member to be used
in the same method
Abstract
A base layer, which is supposed to be burnt off by baking, is
formed on an unbaked member such as ceramic green sheet or
laminated ceramic green sheets. This base layer improves ink
acceptability of the unbaked ceramic member particularly for low
viscosity ink such as jet-ink, and prevents oozing, draining,
uneven thickness. This structure thus allows the inkjet to form a
precise pattern. The base layer is burnt off at the baking step in
the manufacturing process of electronic components, thus it does
not adversely affect the reliability of the electronic
component.
Inventors: |
Nakao, Keiichi; (Osaka,
JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Assignee: |
MATSUSHITA ELECTRIC INDUSTRIAL CO.,
LTD.
Osaka
JP
|
Family ID: |
18972151 |
Appl. No.: |
11/048737 |
Filed: |
February 3, 2005 |
Current U.S.
Class: |
29/890.1 |
Current CPC
Class: |
H01L 21/4867 20130101;
H05K 1/0306 20130101; H05K 1/092 20130101; H05K 3/1208 20130101;
H01G 4/0085 20130101; H05K 2203/0783 20130101; Y10T 29/49155
20150115; H05K 2203/013 20130101; H05K 2203/1163 20130101; H01G
4/12 20130101; Y10T 29/49401 20150115; H05K 3/386 20130101; H05K
3/125 20130101 |
Class at
Publication: |
029/890.1 |
International
Class: |
B41J 002/045 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 20, 2001 |
JP |
2001-122442 |
Claims
1-29. (canceled)
30. Unbaked ceramic substrate including base layer which contains
organic substance, of which thickness is not more than 20 .mu.m on
surface of the base layer, wherein the organic substance is burnt
off by baking at a temperature not lower than 300.degree. C.
31. The unbaked ceramic substrate of claim 30, wherein the base
layer includes one of metal powder and oxide powder in a quantity
ranging from not less than 1 weight % to not more than 80 weight %
and having a particle diameter ranging from not less than 0.001
.mu.m to not more than 10 .mu.m.
32. The unbaked ceramic substrate of claim 30, wherein the base
layer further includes carboxylic acid at least 0.01 weight %.
33. Unbaked ceramic substrate including a component, which reacts
on additive component of organic substance included in ink to cause
gelling, at least 0.01 weight %, wherein the component is burnt off
by baking at a temperature not lower than 300.degree. C.
34. Base layer including a component, which reacts on additive
component of organic substance included in ink to cause gelling, at
least 0.01 weight %, wherein the component is burnt off by baking
at a temperature not lower than 300.degree. C.
35. The base layer as defined in claim 34 having a thickness of not
more than 20 .mu.m and comprising material which includes one of
metal powder and oxide powder, of which particle diameter ranges
from not less than 0.001 .mu.m to not more than 10 .mu.m, in a
quantity of at least 0.01 weight %.
36. The base layer of claim 34 including organic material, which is
to be burnt off by baking, at least 0.1 weight %.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of manufacturing
ceramic electronic components such as ceramic parts, laminated
ceramic capacitors, LC filters, and composite high-frequency
electronic components. The method uses a computer-controlled
ink-jet apparatus, which jets ink to form the foregoing various
electronic components on non-contact basis.
BACKGROUND ART
[0002] A conventional method of manufacturing various ceramic
electronic components, first of all, prints a predetermined
electrode pattern on an unbaked ceramic member such as a green
sheet of ceramic by, e.g., screen printing. Next, laminate the
ceramic green sheets on which the electrode patterns are printed,
then cut the laminated sheet in a given shape, and bake them.
Finally form external electrodes. Another method forms conductive
or insulating patterns on an unbaked ceramic member, then bake the
member.
[0003] A conventional printing method such as a screen printing can
form electrodes in an identical shape; however, it is not good at
forming electrodes of different patterns, i.e., small batches of a
variety of products, or forming electrodes on non-contact basis, or
forming electrodes at a high speed. Japanese Patent Application
Non-examined Publication No. 2000-327964 and No. 2000-182889
disclose methods of manufacturing electronic components using
likjet for overcoming the foregoing problems. However, forming an
electrode pattern using inkjet depends on surface condition of a
substrate on which the pattern is to be printed. Thus some ceramic
green sheet repels water or oil of ink, which produces non-uniform
thickness of the printed pattern. As a result, a desirable
electrode pattern cannot be formed.
[0004] Problems of ink acceptability of those substrates to be
printed are described with reference to FIG. 11. FIG. 11A and FIG.
11B show an electrode-shape required as a ceramic electronic
component. Electrode pattern 1 shown in FIG. 11A has no pin-hole
therein, and is required to have a uniform thickness and to be a
highly accurate fine pattern. Therefore, in FIG. 11B, electrode
pattern 1 is formed on a ceramic green sheet on base film 2 in a
uniform thickness.
[0005] FIG. 11C illustrates an electrode pattern formed with
conventional inkjet. As shown in FIG. 11C, the electrode patterns
formed with inkjet on the ceramic green sheet are deformed due to
repelling the jetted ink on the surface because the ceramic green
sheet does not have ink acceptability. FIG. 11D is a sectional view
of FIG. 11C and shows a cross section of the electrode patterns
formed with the conventional inkjet. As shown in FIG. 11C and FIG.
11D, electrode patterns 4 are repelled and deformed, which is
caused by poor wetness, namely, low ink-acceptability of the
ceramic green sheet on which patterns are to be printed. This is a
similar phenomenon as a water drop is repelled on a base substrate
which has been processed to repel water and oil. If such an
ink-repellant phenomenon occurs in an electrode pattern, pinhole 5
tends to be formed inside electrode pattern 4. As a result,
repelled electrode pattern 4 ends up having non-uniform
thickness.
[0006] As such, jetted ink landed on the surface of the substrate
is deformed as shown in FIG. 11C and FIG. 11D because the viscosity
of the ink is as low as 0.01-0.1 poise and extremely subjected to
surface tension of the substrate on which patterns are to be
printed. Thus the landed ink is deformed before the ink is dried or
cured. In the case of screen printing, on the other hand, the
viscosity of ink is as high as several hundreds poise, and the ink
is hardly deformed. In a case of an inkjet printer using papers
available in the consumer market, since landed ink soaks into the
paper, such uneven printing does not occur. However, in the case of
ceramic electronic component posed in the present invention, if
jetted ink soaks into a ceramic green sheet, electrical insulation
or reliability of a finished component is sometimes substantially
degraded. Quick-drying of landed ink is one of measures against
such a problem. However, quick-drying ink tends to dry and harden
at a tip of a printer head of an inkjet apparatus, and eventually
clogs the printer head. Therefore, it is not good at producing
stable print for long hours.
[0007] As discussed above, efforts have been made for printing
given electrode-patterns accurately using inkjet; however, as shown
in FIG. 11C and FIG. 11D, irregular bumps and dips are formed in a
sectional view of electrode patterns, thus a required electronic
component cannot be produced.
[0008] An apparatus that forms a given three-dimensional structure
using laser beam is recently commercialized. This apparatus exposes
photo-sensitive resin to laser beam and cures the resin, and
repeats this operation plural times before forming the given
three-dimensional structure. The finished three-dimensional
structure is formed of resin, therefore if it is sintered, an
electronic component cannot be produced. If an electrode or a
member for forming an electronic component such as ceramic is added
to this kind of photo-sensitive resin, it becomes difficult to cure
this subject with light.
[0009] Japanese Patent Application Non-examined Publication No.
H02-415702 discloses a method of forming a three-dimensional
structure using inkjet. This method deposits a first layer of
powder material at a limited area, then deposits binder at a
selected area of the powder material layer, so that the bound
powder material is formed at the selected area before a component
is produced. This method repeats the foregoing operation selected
number of times for producing a given plastic component. Thus a
successive layer is formed at the selected area of the bound powder
material. Then un-bound powder material is removed, whereby a
three-dimensional structure is formed. However, in the case of the
disclosure discussed above, the inkjet apparatus jets binder for
powder, and the binder does not include the powder. When the
three-dimensional structure is taken out, surplus powder should be
brushed off. Further, this disclosure has difficulty for forming a
three-dimensional structure including plural members such as
ceramic, electrodes and so on, which are necessary for an
electronic component.
SUMMARY OF THE INVENTION
[0010] The present invention proposes a method of manufacturing
electronic components, this method forms a base layer, which is to
be burnt off by baking, on-the surface of ceramic green sheet or
ceramic green laminated body, i.e., the sheet or the body is not
yet baked. The burn-off base layer improves ink acceptability,
particularly for the ink of low viscosity such as jet-ink, of the
unbaked ceramic members. Thus oozing, dripping of ink or uneven
thickness can be prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1A shows a sectional view of formation of an electrode
pattern on a base layer in accordance with a first exemplary
embodiment of the present invention.
[0012] FIG. 1B shows a sectional view of the formation of the
electrode pattern on the base layer in accordance with the first
exemplary embodiment of the present invention.
[0013] FIG. 1C shows a sectional view of the formation of the
electrode pattern on the base layer in accordance with the first
exemplary embodiment of the present invention.
[0014] FIG. 2A shows a perspective view of an electrode pattern
with a base layer and that without a base layer.
[0015] FIG. 2B shows characteristics of the electrode pattern with
the base layer and that without the base layer.
[0016] FIG. 3A shows a sectional view illustrating an electrode
pattern with a base layer and that without a base layer due to
drying.
[0017] FIG. 3B shows a sectional view illustrating an electrode
pattern with a base layer and that without a base layer due to
drying.
[0018] FIG. 3C shows a sectional view illustrating an electrode
pattern with a base layer and that without a base layer due to
drying.
[0019] FIG. 4A illustrates a status when a printer discharges a
sheet.
[0020] FIG. 4B illustrates a status when a printer discharges a
sheet.
[0021] FIG. 4C illustrates a status when a printer discharges a
sheet.
[0022] FIG. 5 illustrates that solvent contained in ink soaks into
a base layer, whereby the ink is set.
[0023] FIG. 6 illustrates that solvent contained in ink soaks into
a base layer, whereby the ink is set.
[0024] FIG. 7 illustrates a case where gelling reaction is
used.
[0025] FIG. 8 illustrates a case where reaction between organic
components.
[0026] FIG. 9 illustrates a case where reaction between inks
thereby forming a three dimensional structure.
[0027] FIG. 10 illustrates a sectional view of a three dimensional
structure formed in an exemplary embodiment of the present
invention.
[0028] FIG. 11A shows a plan view of a required electrode
pattern.
[0029] FIG. 11B shows a sectional view of the required electrode
pattern.
[0030] FIG. 11C shows a plan view of an electrode pattern formed by
a conventional method.
[0031] FIG. 11D shows a sectional view of the electrode pattern
formed by a conventional method.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
Exemplary Embodiment 1
[0032] In this embodiment, formation of an electrode pattern onto a
ceramic green sheet is demonstrated. FIG. 1A-FIG. 1C illustrate a
method of forming an electrode pattern on the surface of a ceramic
green sheet having a base layer. FIG. 1A shows a sectional view
illustrating a method of forming a given electrode pattern by
ink;et method on a ceramic green sheet having a base layer. FIG. 1B
shows the given electrode pattern thus formed. In FIG. 1A inkjet
apparatus 7 is loaded with predetermined ink, and jets droplet 8
responsive to an external signal. The external signal can adjust
not only jetting of droplet 8 but also a size (volume, quantity and
diameter) of droplet 8. On base film 2, ceramic green sheet 3 is
formed, and on top the surface of sheet 3, burn-off base layer 11
that is a feature of the present invention is formed. According to
the present invention, plural droplets 8 jetted from inkjet
apparatus 7 land on burn-off base layer 11 and form a given
electrode-ink-pattern 1.
[0033] An example of the electrode pattern thus formed on the
ceramic green sheet is shown in FIG. 1B, in which electrode pattern
1 free from oozing is accurately formed as the design requests.
FIG. 1C is a sectional view cut along a line at anyplace in FIG.
1B. As shown in FIG. 1C, electrode pattern 1 according to the
present invention is formed in an uniform thickness on burn-off
base layer 11.
[0034] Burn-off base layer 11 of the present invention is formed on
the surface of ceramic green sheet 3, whereby droplet 8 after it
landed on green sheet 3 is not flowed or repelled due to the
gravity or the surface tension (the surface tension of the surface
of ink, the surface tension of the base layer.) Burn-off base layer
11 of the present invention is burnt off in a baking step prepared
later and disappears, so that it does not adversely affect the
reliability of the finished electronic component.
[0035] To be more specific about the foregoing method, ceramic
green sheet 3 used in the first embodiment is formed by applying
ceramic slurry onto resin film such that the solid content of the
slurry becomes a thickness of several microns. The ceramic slurry
is produced by mixing and dispersing ceramic powder, of which
temperature characteristic shows B of EIAJ standard, and made of
mainly barium titanate into mixed solution including butyl acetate,
phthalate plasticizer, and butyral resin.
[0036] Next, an inkjet apparatus available in the consumer market
prints the given electrode pattern 1 with commercial water soluble
black ink on the ceramic green sheet 3. The result is shown in FIG.
11C. The ink lands on the ceramic green sheet and is repelled
immediately like beads of water. As a result, target electrode
pattern 1 cannot be formed. This is because the ceramic green sheet
is not hydrophilic, and the water soluble ink landed does not soak
into the surface of the sheet, but the ink is repelled by the
surface tension of the base layer.
[0037] Thus water soluble resin is used as burn-off base layer 11,
and the resin is dissolved in water and applied to the ceramic
green sheet such that a dried thickness becomes 0.5 micron. In this
embodiment, commercially available polyvinyl acetal (e.g., KW1 or
KW3 manufactured by Sekisui Chemical Co. Ltd.) is used as water
soluble resin. A commercially available inkjet apparatus jets the
commercially available water-soluble black ink onto ceramic green
sheet 3 on which burn-off base layer 11 is formed. The result is
shown in FIG. 1B, i.e., accurate electrode pattern 1 free from
deformation is obtained. Thus hydrophilic burn-off base layer 11
prepared on the poorly hydrophilic (highly water repellent) ceramic
green sheet can prevent electrode pattern 1 from being deformed
using water-soluble ink.
[0038] For the comparison purpose, the same test is done using a
ceramic green sheet formed of water-soluble resin. Water-soluble
polyvinyl acetal resin is dissolved in water, glycol (plasticizer),
and alcohol (for adjusting a drying speed) to produce solution of
water-soluble resin. The foregoing ceramic powder is mixed and
dispersed into this solution to produce ceramic slurry. An
applicator applies the slurry onto resin film such that a thickness
of the slurry becomes several microns. The given electrode pattern
1 is printed on the surface of the slurry with the water-soluble
black ink available in the market, then the water-soluble ink not
only dissolves the water-soluble ceramic green sheet, but also
deforms the electrode pattern, an eventually makes holes on the
ceramic green sheet.
[0039] In other words, water-soluble jetted ink is repelled on the
ceramic green sheet of non water-soluble, and water-soluble jetted
ink on the water-soluble ceramic green sheet dissolves the
sheet.
[0040] On the other hand, when non water-soluble (i.e., poorly ink
acceptable) ceramic green sheet demonstrated in this embodiment is
equipped with a thin hydrophilic burn-off base layer 11 on its
surface, the green sheet obtains ink acceptability for
water-soluble jetted ink and prevents the jetted ink from soaking
into the sheet.
[0041] Next, a trial product of ink supposed to be used in an
inkjet apparatus is employed in a similar experiment. The ink is
made of nickel particles, which is turned into jet-ink using a
method of manufacturing water-soluble ink, the method is disclosed
in Japanese Patent Application Non-examined Publication No.
H11-102615. The ink thus manufactured is used for printing on both
surfaces of ceramic green sheet 3 and burn-off base layer 11
provided on top of sheet 3 using inkjet apparatus 7. On the sheet 3
of non water-soluble, the ink is greatly repelled and deformed due
to water repellency of the surface. If water-soluble ceramic green
sheet is used, the ink dissolves the sheet. On the other hand, on
the surface of the burn-off base layer, the ink is not repelled but
formed into a uniform thickness accurately. Being left for long
hours, the ink keeps its pattern free from deformation.
[0042] Prepare several hundreds of ceramic sheets, each having
burn-off base layer on which electrode pattern 1 is formed, then
laminate 300 sheets such that electrode pattern 1 shifts by a given
distance. Cut the 300 sheets into squares of 2.5 mm.times.1.6 mm
size, then bake the cut pieces, and finally form electrodes to
complete laminated ceramic capacitors. The laminated ceramic
capacitor thus manufactured is excellent in both initial properties
and reliability. A scanning electron microscope cannot observe
burn-off base layer 11 on a cross section of this capacitor,
because the base layer of the present invention is burn off. The
burn-off base layer made of mainly burn-off material such as resin
is burn off and volatilized during the baking, and does not remain
in the finished electronic component, thus the base layer does not
adversely affect the finished product.
[0043] In a case of forming burn-off base layer 11 of only resin,
the thickness of the base layer is preferably not more than 20
microns, and more preferably it is not more than 5 microns. If the
thickness of burn-off base layer 11 made of mainly resin is not
less than 20 microns, defectives such as inter layer peeling occur
in some products. Adding a ceramic member inside burn-off base
layer 11 is effective to prevent the inter layer peeling.
Exemplary Embodiment 2 (Advantage of Reducing Unevenness)
[0044] In the foregoing first embodiment, it is demonstrated that
electrode pattern 1 is formed on the ceramic green sheet on which
burn-off base layer 11 is prepared. In this second embodiment, it
is demonstrated that uneven thickness of electrode film applied
depends on the presence of burn-off base layer 11.
[0045] FIG. 2A illustrates a case where burn-off base layer 11 is
formed on only parts of the surface of ceramic green sheet 3. The
advantage of burn-off base layer 11 is described using FIG. 2A,
which shows a uniform thickness at an area where burn-off base
layer 11 is formed and greatly uneven thickness at electrode
patterns 4 formed directly on the ceramic green sheet without base
layer 11. FIG. 2B shows the thicknesses of electrode patterns 1 and
4 shown in FIG. 2A measured with fluorescent X-ray. In FIG. 2B, the
X-axis represents pattern widths (mm) and the Y-axis represents
applied amount of Ni per unit area (mg/mm.sup.2). The spot diameter
of the fluorescent X-ray is 0.1 mm which increases resolution in
measuring. In FIG. 2B, black circle .circle-solid. indicates the
electrode pattern with the burn-off base layer proposed by the
present invention and corresponds to electrode pattern 1 shown in
FIG. 2A. In FIG. 2B, white circle .largecircle. indicates the
electrode pattern without burn-off base layer 11 and corresponds to
electrode pattern 4 with uneven thickness shown in FIG. 2A.
[0046] As shown in FIG. 2B, in the case of burn-off base layer 11
of the present invention being available, an uniform thickness is
obtained overall the pattern. On the other hand, in the case of
burn-off base layer 11 being not available, a little amount of Ni
is applied around electrode pattern 4 but a greater amount of Ni is
applied at the center of electrode pattern 4. Thus substantially
uneven application is observed in the axial direction.
[0047] Next, the uneven application discussed above is detailed
using FIG. 3, which monitors drying procedure of electrode patterns
1 and 4 shown in FIG. 2A with sectional views. On the left sides
(burn-off base layer 11 is available) of FIG. 3A-FIG. 3C, a droplet
(not shown) jetted from an inkjet apparatus (not shown) lands on
burn-off base layer 11 and forms pattern 1 as shown in FIG. 3A, and
solvent component in the ink is volatilized with a lapse of time.
Then the ink is gradually dried and thinned keeping the uniform
thickness and the shape shown in the sectional view as shown in
FIG. 3B and FIG. 3C.
[0048] On the other hand, in the right area where burn-off base
layer 11 is not formed, a droplet (not shown) landed on the ceramic
green sheet of water repellency is repelled as if a bead of water,
as shown in FIG. 3A, due to the water repellency of the surface.
Its cross section shows a rise at the center. A peripheral section
where the thickness of electrode pattern 4 is the thinnest among
other sections starts volatilizing, and other sections follow. The
center section having the greatest thickness remains escaping being
dried to the end. At this time, the ink in liquid condition (not
dried yet) is pulled by the surface tension to the center section,
thus cracks 12 and pinholes (not shown) tend to occur between the
peripheral and center sections. Electrode pattern 4, where such an
uneven thickness occurs, is not suitable for manufacturing
electronic components of high performance required from the
market.
[0049] Next, a phenomenon, in which solvent component in the ink
soaks into the burn-off base layer, is explained as follows: FIG. 5
and FIG. 6 illustrate that the solvent component in the ink is
absorbed in the burn-off base layer thereby setting the ink. In
FIG. 5, droplet 8 jetted from the inkjet apparatus (not shown)
lands on burn-off base layer 11 and forms landed droplet 13. At
this time, some solvent component out of droplet 8 soaks into base
layer 11 along the arrow marks. FIG. 6A and FIG. 6B show a printing
procedure. In actual, thousands or millions of droplets 8 per
second are jetted from the inkjet apparatus (not shown), and landed
droplets 13 are piled up on the sheet as shown in FIG. 6A to
produce a given thickness. In this case, some solvent component
from plural landed droplets 13 are absorbed into base layer 11
along the arrow marks. Landed droplets 8, from which some solvent
is removed, increase their viscosity and are integrated with each
other to form electrode pattern 1 shown in FIG. 6B. In a case of
printing on a regular paper with the inkjet, the ink is completely
absorbed into the paper because the ink is dye ink. However,
according to the present invention, ink including powder material
is used and the sheet has low absorption of ink. In such a case, a
highly accurate pattern is obtainable only after the burn-off base
layer is formed, which is proposed by the present invention.
Exemplary Embodiment 3
[0050] In the foregoing second embodiment, reducing uneven
thickness using burn-off base layer 11 is described. In this third
embodiment, uneven thickness of an applied film is further reduced
using chemical reaction between burn-off base layer 11 and ink. In
this embodiment, the burn-off base layer contains organic
carboxylic acid.
[0051] First, as the material of burn-off base layer 11, employ
anionic polyvinyl alcohol resin (manufactured by KURARE Inc.), and
dissolve the resin in pure water. Then apply the resin dissolved in
the pure water onto ceramic green sheet 3 such that a thickness of
dried resin becomes 0.5 micron. Burn-off base layer 11 of anion
resin is thus formed.
[0052] Next, as the material of ink, dissolve nonionic polyvinyl
alcohol resin manufactured by KURARE Inc. in pure water. Then add
some nonionic dispersant, nonionic plasticizer (glycerin,
polyethylene glycol are used) and Ni powder to the resin dissolved
in the pure water. Nonionic ink is thus produced. Load the nonionic
ink into a printer (made by EPSON Inc., model No. MJ510C) and print
patterns in 720 dpi. FIG. 4 illustrates this printing. In FIG. 4C,
the ceramic green sheet on which electrodes are printed is
discharged from the printer in a slanted manner, so that the ink
flows in the electrode pattern and uneven print tends to occur.
[0053] In this third embodiment, electrode pattern 1 is formed on
burn-off base layer 11; however, uneven print due to the ink flow
does not occur. Because at the instant when nonionic ink lands on
anionic burn-off base layer 11, a kind of gelling reaction between
nonion component in the ink and anionic base layer 11 starts, which
prevents the landed ink from flowing.
[0054] This situation is detailed with reference to FIG. 4. As
shown in FIG. 4A, burn-off base layer 11 is formed on the left half
of ceramic green sheet 3, on which electrode patterns are to be
printed. Inkjet apparatus 7 prints given electrode patterns on
sheet 3 at both the areas, one has base layer 11 and the other does
not have. FIG. 4B shows electrode pattern 1 printed on burn-off
base layer 11, where the ink does not drain although sheet 3 is
held vertically with the ink still wet. In other words, non-uniform
thickness does not occur. FIG. 4C, on the other hand, shows a
status without burn-off base layer 11, where the ink of the
patterns drains downward when sheet 3 is held vertically with the
ink still wet.
[0055] In the case of using the burn-off base layer made of
nonionic resin, the same material as the ink, the ink is formed
accurately; however, a pattern formation by the inkjet apparatus
onto the base layer causes the ink to drain in the pattern as shown
in FIG. 4C. This phenomenon occurs when an electrode pattern still
wet is placed vertically as shown in FIG. 4A or the ink is jetted
onto the sheet vertically held. Then the ink drains in the pattern
due to its own weight or non-uniform thickness occurs in the
pattern. On the other hand, in the case of using the burn-off base
layer made of anionic resin, a pattern formation on to the base
layer does not cause the ink to drain in the pattern or non-uniform
thickness does not occur in the pattern, although an electrode
pattern still wet is placed vertically or the ink is jetted onto
the sheet vertically held.
[0056] According to the present invention, reaction between a
component included in the burn-off base layer reacts and a
component included in the ink allows the pattern formed on the base
layer to keep its shape accurately before the solvent component
volatilizes. In other words, even if the wet ink landed on the
burn-off base layer is put in a drier and blown by volume hot air
at a high speed, the printed pattern or its cross sectional shape
is not adversely affected. Thus the manufacturing method of the
present invention allows a drier to be placed in conjunction with
the inkjet apparatus, and this structure can save the manufacturing
equipment a lot of space.
[0057] A use of the advantage of the present invention in
commercially available and high-speed inkjet printers, which employ
various high-speed heads, allows jet-ink used for various
electronic components to be dried free from adverse influence to
their cross sectional shapes. The advantage is applicable in a high
speed printing such as several meters per minute or several-hundred
meters per minute. Since the present invention can print electrode
patterns free from uneven thickness on a sheet held vertically, a
floor space for the printing apparatus can be reduced, and the
printing apparatus can be integrated into another apparatus with
ease. This advantage allows simplifying the apparatus, lowering the
cost, and providing a clean room with ease. As a result, finished
products can be manufactured at a reasonable cost and the yield
ratio can be improved.
[0058] As discussed above, the material added to the ink and the
material added to burn-off base layer 11 contact with each other to
start gelling reaction, thereby curing the ink instantaneously.
High strength of cured ink is not required in this curing reaction,
but soft curing or gelling that can prevent the ink from draining
is good enough. A combination of the two materials is, e.g.,
anionic material with nonionic material, anionic material with
cationic material, nonionic material with cationic material.
Reactions between those materials are described as a reaction
between a donor and an acceptor in the fourth embodiment and
onward.
[0059] The present invention finds that the dispersant can be used
for starting the gelling reaction. For instance, polycarboxylic
acid based dispersant of anionic material, made by KAO inc. or
SUN-NOPCO and available in the market, is used for producing ink,
and nonionic resin is used as the burn-off base layer. In this
case, a similar reaction to what is discussed above can be
expected. This chemical reaction is considered similar to the
gelling reaction proper to water-soluble resin, i.e., the gelling
reaction between polyvinyl-alcohol-based synthetic starch available
in the market being mixed with borax. Materials such as borax
containing sodium or boric acid leave residual component, which
affects reliability of the electronic component, after the material
is baked. Therefore those materials are not good for burn-off base
layer 11 of the present invention.
[0060] It is desirable to use organic acid or organic base which
does not produce residual component after the baking for realizing
the manufacturing method of the present invention. Several ten
thousands of such organic substances are known in the world, and an
ordinarily skilled person in the organic chemistry can optimize
those materials with ease. According to the experiments by the
inventors, an organic acid which includes at least carboxyl group
(--COOH) is useful from the view point of reliability.
[0061] Resin including carboxylic acid is used as either one of the
ink or the burn-off base layer, and resin or organic substance of
cationic or nonionic one is used as the other one (base layer or
ink), whereby the gelling reaction can be produced. Any organic
compound R-COOH having carboxyl group can be the resin containing
carboxylic acid where R represents hydrocarbon group and can be
used for the present invention.
[0062] This reaction is considered similar to a kind of salt out
reaction. In the present invention, in the case of producing metal
salt, such as sodium, of alkaline material or alkaline earth
material, residuals after the baking sometimes affect adversely to
reliability. Thus addition compound of organic base and acid, or
organic substance is preferably produced instead of metal salt from
the salt out reaction.
[0063] Besides ceramic member in the burn-off base layer,
conductive powder or magnetic powder can be added, so that the base
layer becomes more functional. For instance, the materials proposed
here to be used in the burn-off base layer can be added to the
ceramic slurry which is the material of a ceramic green sheet or an
unbaked ceramic member. In other words, the material supposed to
react on the ink is added to the ceramic green sheet or unbaked
ceramic member in advance, so that a ceramic green sheet having
higher ink-acceptability can be produced.
[0064] In the present invention, the ink preferably has a viscosity
of less than 2 poise. In the case of viscosity not less than 2
poise, an inkjet apparatus available in the market clogs sometimes
with the ink. The best way to prevent the inkjet apparatus from
clogging is to dilute the ink with water-soluble solvent such as
water or glycol; however, the thinner ink tends to produce uneven
print on the sheet. The manufacturing method of the present
invention uses chemical reaction between the sheet and the ink,
therefore, even if the ink is diluted, uneven print can be
suppressed, and the ink can be dried fast.
Exemplary Embodiment 4
[0065] In this fourth embodiment, the gelling reaction, produced by
landing the jet-ink on the burn-off base layer, is described with
reference to FIGS. 7 and 8. As shown in FIG. 7, reactive members
are added to the ink and the base layer in advance. The reactive
member in the ink and that in the base layer contact with each
other to start gelling reaction, thereby setting the ink. The ink
forming droplet 8 includes in advance donor 14 corresponding to the
reactive member, and base layer 11 includes in advance acceptor 15
corresponding to the reactive member. In the case of FIG. 7,
droplet 8 including donor 14 lands on base layer 11 which includes
acceptor 15, then donor 14 and acceptor 15 react with each other,
which produces reacted donor 16 and reacted acceptor 17. Reacted
donor 16 and reacted acceptor 17 start gelling the ink. As shown in
FIG. 7, after the gelling, there still remain unreacted donors 14
and unreacted accpetors 15 in landed droplet 13. Those unreacted
donors 14 and acceptors 15 remained in the droplet 13 can increase
the thickness, volume, amount and weight of landed droplet 13 as
shown in FIG. 6.
[0066] Next, the theory of reducing uneven print is demonstrated
with reference to FIG. 8, which illustrates a case where a reaction
between organic components is used. In this fourth embodiment, an
organic component added to the ink and an organic component added
in advance to the base layer react with each other, which starts
gelling and sets the ink. In FIG. 8, among organic substance 18
such as resin or dispersant, resin 18a included in droplet 8
contains donor 14 as a functional group. Organic substance 18b
included in base layer 11 contains acceptor 15 as a functional
group. In this embodiment, droplet 8 lands on burn-off base layer
11 to form landed droplet 13. Then donor 14 of resin 18a in droplet
13 and acceptor 15 of organic substance 18b in base layer 11
produce gelling reaction.
Exemplary Embodiment 5
[0067] In the fifth embodiment, plural inks are used, i.e., one
jet-ink containing non-burn-off material (hereinafter called
non-burn-off ink) and another jet-ink containing burn-off material
(hereinafter called burn-off ink). A given pattern is printed on
one base using the non-burn-off ink and the burn-off ink
alternately. This operation is repeated plural times to form a
three-dimensional structure. According to the present invention,
the members reactive with each other (e.g., donor and acceptor) are
added to the non-burn-off ink and the burn-off ink respectively, so
that the inks start gelling upon contacting with each other, which
eliminates a step of drying the inks. Thus the inks do not mix with
each other and are free from draining or oozing, and can form a
given three dimensional structure. The structure thus formed is
dried and baked, whereby the part formed by the burn-off ink is
burnt off and volatilized. The non-burn-off material in the
non-burn-off ink contained in the three dimensional structure
remains as it is and is sintered to form the given structure.
[0068] FIG. 9 illustrates a case where a reactive member is added
to the jet-ink to form a three dimensional structure. In FIG. 9,
droplets 19 to the base layer form burn-off layer 11 after the
landing. Droplets 8 jetted from the inkjet apparatus (not shown)
land and form electrode pattern 1. Droplets 19 jetted from the
inkjet apparatus also land and form burn-off base layer 11. In this
embodiment, droplets 8 and droplets 19 contact with each other
after the landing and start gelling as discussed in the previous
embodiments, therefore, the patterns do not ooze to each other. On
top of the patterns thus gelled, new patterns are further formed,
as shown in FIG. 9, with droplets 8 and 19 jetted from the inkjet
apparatus, thereby forming a three dimensional structure. The
structure thus formed is finally dried and baked, so that the part
formed by droplets 8 remains as the three dimensional structure and
the part formed by droplets 19 is burnt off. The three dimensional
structure can be thus manufactured. Particularly in this
embodiment, just before the baking, burn-off base layer 11 as a
protective member protects the three dimensional structure until it
is baked. The three dimensional structure can be also formed being
buried in the base layer. Therefore if more complicated and
elaborate work is required in a three dimensional structure, this
method can manufacture it precisely and in accurate dimensions.
[0069] The baking of a three dimensional structure sometimes causes
burning shrinkage in the structure by 10 to 50% depending on a
baking condition. In such a case, the three dimensional CAD pattern
is revised responsive to the shrinkage ratio. Particularly in this
embodiment, molds are not used, and three dimensional structure can
be directly formed by the inkjet. Thus only a change of dimension
in the three dimensional CAD can revise a burning shrinkage ratio,
so that a highly accurate structure can be formed in a short
time.
[0070] Material hard to be sintered such as ceramic members
including alumina or zirconia can be added to the burn-off base
layer, so that a three dimensional structure is not loosen or
deformed during the baking.
Exemplary Embodiment 6
[0071] In the sixth embodiment, non-burn-off materials different
from each other are put respectively into different inks reactive
with each other, and a given pattern is formed on a single base
using these inks. This operation is repeated plural times to form a
three dimensional structure. Particularly in this embodiment,
reactive members with each other are put in the respective inks, so
that the inks still wet do not mix with each other and are free
from draining or oozing. As a result, a three dimensional structure
still wet or in gel status can be formed. The three dimensional
structure thus formed is dried and baked, whereby the three
dimensional structure made of the non-burn-off materials different
from each other is formed.
[0072] FIG. 10 shows a sectional view of the three dimensional
electronic component produced in accordance with the sixth
embodiment. As shown in FIG. 10, ink (not shown) for ceramic lands
and forms ceramic 20, ink (not shown) for electrode lands and forms
electrode 21, and ink (not shown) for via hole lands and forms via
hole 22. The three dimensional structure thus formed is then baked
at a given temperature, and external electrodes are formed before
it is completed as a given electronic component. In the sixth
embodiment, donors or acceptors are added individually to the
respective inks for ceramic, electrode and via hole. Thus those
inks are gelled to avoid mixing with each other, and a required
printed structure can be formed.
[0073] As the ink for forming ceramic 20, the following materials
such as glass, dielectric body, magnetic body, or ceramic can be
used as far as they are oxide.
Exemplary Embodiment 7
[0074] In the seventh embodiment, the reactive member is described,
which is to be used for forming a three dimensional structure using
ink and burn-off base layer, or plural inks. In this embodiment,
donors are added to ink and acceptors are added to the burn-off
base layer. The donor and acceptor are reactive with each other. At
the moment when the ink including the donors lands on the base
layer which includes the acceptors, the donors and acceptors react
with each other. Thus the landed ink is prevented from draining. As
a matter of course, when the ink contains acceptors and the
burn-off base layer contains donors, draining of the ink is also
prevented. In this embodiment, for the purpose of simple
description, the reactive member contained in the ink jetted from a
printer head is called donor, and the reactive member contained in
the ink accepting side is called acceptor.
Exemplary Embodiment 8
[0075] In the eighth embodiment, a salting out member is used in
donors and acceptors that produce gelling reaction. First, anionic
PVA is dissolved in water, and this water solution is applied and
dried as a burn-off base layer of anionic material. To be more
specific, PVA is modified by carboxylic group, meanwhile this
member is purchased from KURARE Inc. The ink is made of a given
powder with additive of nonionic or cationic material. Then an
inkjet apparatus jets the ink onto the base layer of anionic
material to form a given pattern. At the instant when the ink lands
on the base layer, the ink reacts on anionic resin of the base
layer and starts gelling. In this case, the water solution of
anionic PVA is made of commercial anionic PVA in a quantity of 1 to
50 g, dissolved in the pure water of 100 g. If the amount of PVA is
less than 1 g, the concentration of resin solution is too low and a
necessary film thickness sometimes cannot be obtained. If the
amount of PVA is not less than 50 g, the viscosity of the resin
solution is too high and it is hard to apply the solution. In the
case of thinning the base layer thickness not more than 0.1 micron,
or increasing the thickness of the ink not less than 10 micron, the
absolute amount of the anionic resin contained in the base layer
eventually becomes small, which lowers reactivity with the ink. In
such a case, organic acid can be added to the anionic base layer,
thereby strengthening the gelling reaction. For instance, dissolve
anionic PVA available in the market of 1 g to 40 g into pure water
of 100 g, and dissolve organic acid such as citric acid or lactic
acid of 0.1 g to 10 g therein. The water solution thus produced is
applied and dried to be the burn-off base layer. Other than anionic
resin, formic acid, acetic acid, oxalic acid, citric acid and
lactic acid can be used as organic acid. One of those organic acids
only or combined with other water-soluble resin can produce a
similar reaction. An effective amount to be added is 0.1 g to 10 g.
A molecular weight of the organic acid is preferably 100 or more
than 100. If the molecular weight is less than 100, the organic
acid added to the base layer sometimes volatilizes and disappears
automatically. If the organic acid is added to the anionic PVA, it
sometimes causes gelling reaction to the PVA instead. To prevent
this problem, it is preferable to add weak organic acid to weak
acid water-soluble resin. Strong acid and weak acid are classified
based on functional groups, and relevant literatures available in
the market tell the classification.
[0076] As anionic materials, it is preferable to select the
material including functional group such as NH--, OH--, CO.sub.3--,
HCO.sub.3--, CH.sub.3CO.sub.2--, and the like. Dispersant, resin of
phosphoric acid base, S--, HS--, or HSO.sub.4-- tends to attach to
powder surface, and they are very useful as additive to the ink
because those materials can increase dispersion and stability of
the ink. Be cautious that an amount of those additive is preferably
less than 1 g because too much additive would damage the oven
during the baking or degrade the reliability of the product.
[0077] In the case of using water-soluble resin as burn-off base
layer 11, the following materials can be used: polyvinyl acetal
resin, polyvinyl alcohol resin, methyl cellulose resin,
carboxy-methyl cellulose resin, hydroxy-propyl cellulose resin, and
acrylic resin. The resins discussed above are added to one of
jet-ink or the base layer, and organic acid or organic base is
added to the other one, thereby producing the gelling reaction.
[0078] When metals such as nickel, in particular, is used in ink
with resin or dispersant of carboxylic acid, the ink thus produced
becomes weak acid, and nickel sometimes dissolves as ion to form
supernatant liquid (nickel ion) of blue-green color. If the ink's
pH is greater than 3, nickel dissolves a little and no serious
problem occurs; however, if the pH is not more than 3 (particularly
not more than 2), the nickel dissolves a lot, which degrades the
properties of a laminated ceramic capacitor having an internal
electrode made of nickel.
Exemplary Embodiment 9
[0079] In the ninth embodiment, a combination of acceptors and
donors employs the members that cause gelling reaction. The
difference in pH of a burn-off base layer from that of jet-ink is
used to produce gelling reaction. For instance, first one uses acid
of less than pH 7 and second one uses base of pH 7 or greater than
pH 7, and acid-base reaction can be used. In a case of using an
acid substance or a basic substance having a small molecular
weight, gelling reaction does not occur and the ink stays
water-soluble status. On the contrary, in a case of using the
substance having a great molecular weight, e.g., more than 1000,
neutralization reaction between the acid and base lowers the
dissoluble concentration of that substance. Thus the substance
cannot be hydrated completely, and parts of the substance separates
out (deposits) in gelled status in the solvent. Meanwhile, a pH
meter available in the market tells whether the ink or base layer
is acidic, basic or neutral. Ink per se is set in a centrifugal
separator, and fine particles in the ink precipitate, the
supernatant liquid thus obtained can be used for measuring pH. To
know the pH of the burn-off base layer, dip the base layer into
pure water, and put it in a centrifugal separator to obtain
supernatant liquid, which is used for measuring the pH. The
supernatant liquid thus obtained can be concentrated upon
request.
[0080] The inventors find that the difference in pH of the burn-off
base layer from that of the jet-ink is preferably not less than 0.5
(more preferably not less than 1). When the difference in pH is not
less than 0.5, polymeric materials, of which molecular weight is at
least 1000, preferably more than several thousands or more than
several ten thousands, can cause gelling reaction because of the
difference of acid and base of their functional groups.
Exemplary Embodiment 10
[0081] In the tenth embodiment, a combination of acceptors and
donors employs the members that cause chemical reaction. A
selection of acidic or neutral burn-off base layer with respect to
basic ink causes similar chemical reaction to what is discussed in
the previous embodiments. For instance, dispersant including amino
group or cationic dispersant is mixed into the ink to produce basic
ink. Basic water-soluble organic solvent of various amines or
dimethyl formanide (DMF) can be added to this ink, so that
dispersibility and stability of the ink improve and also reactivity
of the base layer increases.
[0082] Next, the case where amine is used as basic material is
detailed hereinafter. Amine or amide used in one of the ink or the
burn-off base layer can cause gelling reaction similar to that
discussed in the previous embodiments. Meanwhile primary amine
refers to RNH.sub.2, secondary amine refers to R.sub.2NH, and
tertiary amine refers to R.sub.3N. Any amines can be used in the
present invention. R represents hydrocarbon. As for amide, any
amide of primary amide, secondary amide and tertiary amide can be
used in the present invention. For instance, ethanol amine can be
used in either one of the ink or the base layer. Gelling reaction
can starts when a basic material is used in either one of the ink
or the base layer. In any cases, it is preferable to use pH not
more than 12. If pH is 12 or more than 12, human skin can be
corroded depending on handling the materials.
Exemplary Embodiment 11
[0083] In the eleventh embodiment, a combination of acceptors and
donors utilizes solidifying reaction of protein. The present
invention can utilize the solidifying reaction of protein. This
reaction has been used in manufacturing "tofu" (bean curd). In the
present invention, simple protein such as albumin and globulin, or
gelatin, peptone, keratin, collagen can be used as protein.
[0084] Various proteins are available at a reasonable cost due to
the recent progress of biochemistry, and proteins excellent in
absorption to powder surface or binder component in ink are also
available. In other words, protein component is mixed with ink, and
setting agent such as gluconic acid is mixed with the burn-off base
layer, so that the ink starts solidifying upon contacting of the
ink and the base layer.
[0085] Further, biochemical aggregation, similar to the foregoing
reaction and one of antigen-antibody reactions, can be used. This
reaction refers to a phenomenon where hematid (red blood cell) in
blood aggregates due to antibody reaction to antigen. In this
embodiment, antigen or antibody bonded to the surface of synthetic
resin particles can be used instead of putting hematid in the ink,
so that high sensitivity of arregation is utilized. Thus a very
little amount of such material can be useful in the present
invention. Such materials are available at reasonable costs thanks
to the recent progress of biochemistry. Materials excellent in
absorption to powder surface or binder component in ink are also
available.
Exemplary Embodiment 12
[0086] In the twelfth embodiment, a combination of acceptors and
donors produces dehydrating reaction. Methanol, ethanol or other
higher alcohol or acetone can be added in advance as dehydrating
agent to burn-off base layer 11 in order to gel the ink mixed with
water-soluble resin such as polyvinyl alcohol. At the instance when
this water-soluble ink lands on base layer 11 including the
dehydrating agent, the water component in the ink is removed and
parts of the hydrated ink materials separate out (deposit) or
thicken (body up). Thus the landed ink can keep its shape
accurately. The reaction between the burn-off base layer and the
ink proposed in the present invention can be satisfied with
accompanying the gelling or the increase of viscosity. Therefore,
milk commercially available can be used in the ink, and vinegar
commercially available can be used in the burn-off base layer. It
is generally known that when milk mixes with vinegar, the milk is
gelled. In this case, the component emulsified and dispersed in the
milk is broken. The present invention can utilize such
agglutination reaction of emulsion.
Exemplary Embodiment 13
[0087] In the thirteenth embodiment, non-water-soluble resin is
emulsified in water, and this resin is used instead of
water-soluble resin. For instance, non-water-soluble resin such as
polyvinyl-butyral is emulsified in the water with emulsifying
agent. This product is commercially available. Such emulsifying
results in a nonionic product, a cationic product or an anionic
product depending on an emulsifying agent. A use of polarity
difference in those emulsions thus obtained can cause gelling
reaction similar to those discussed in the previous embodiments.
For instance, when nonionic emulsion is mixed with anionic
emulsion, the emulsions are broken and resin component separates
out into the water solution. This kind of gelling reaction or
separating reaction can be produced by, e.g., adding organic acid,
organic base, or water-soluble anionic resin or cationic resin to
nonionic emulsion.
[0088] Therefore, one of the emulsions discussed above is added to
either one of the ink or the burn-off base layer, and the material
reactive to this emulsion is added to the other one (ink or base
layer), so that setting reaction or solidifying reaction occurs in
colloid solution. Those reactions (gelling, separation of resin,
increasing viscosity, precipitation) make an ink-shape printed by
inkjet more precisely.
[0089] In a case of using latex resin or emulsion resin in burn-off
base layer 11, a particle diameter of those materials is preferably
not more than 5 microns (more preferably not more than 2 microns).
If emulsion particles having diameter of not less than 5 microns
are used in the ink, the printer head tends to clog, and when the
particles are used in the base layer, they cause uneven thickness
of the base layer. Thus the particle diameter not less than 5
microns is not suitable for manufacturing electronic
components.
[0090] As discussed above, non-water-soluble resin can be used in
the present invention, namely, water-soluble resin such as
polyvinyl alcohol is used as emulsifying agent or protective agent
to form emulsion. Anionic material containing carboxyl group can be
used as emulsifying agent, so that anionic emulsion resin is
produced. The anionic emulsion resin thus produced induces a kind
of gelling reaction upon contacting with cationic resin or organic
base, cationic emulsion or nonionic resin.
[0091] A use of emulsion reduces amount of organic solvent used in
the manufacturing process of ink or burn-off base layer. Therefore,
in the manufacturing site, safe and environmental friendly
manufacturing free from fire regulation can be realized.
Exemplary Embodiment 14
[0092] In the fourteenth embodiment, physical gel is used as the
donor and acceptor of the present invention. The physical gel in
this embodiment refers to the gel formed by physical bridge such as
hydrogen bonding or ionic bonding between polymer molecules, or
chelate formation. Such gels can be produced by varying heat, types
of solvents, ion concentration, or pH. The water solution of agar
or gelatin is turned into gel by lowering the temperature, and
turned into sol by raising the temperature. Such a reversible
gelling reaction can be used in the present invention.
[0093] As discussed above, two types of polymer electrolytic
solutions having opposite electric charges to each other are mixed,
thereby producing gel called polyion complex gel. Such a gel is
subjected to various factors including types of solvents, ion
concentration, pH, polymer concentration and the like; however,
optimization of those parameters produces a structure that can
maintain more precise three dimensional shape. For instance,
polycation and polyanion in an equal quantity are added to the ink
and the burn-off base layer respectively, thereby producing neutral
gel in the landed ink.
[0094] Polycarboxylic acid such as polyacrylic acid or strong acid
polymer such as poly(styrene sulfonic acid) is bonded with
alkaline-earth metal, thereby also synthesizing gel. Such bonds is
not a direct bond between metallic ion and ligand, but the bond is
formed via hydration-ion, therefore, gelled ink is obtainable with
ease. In-those reactions, optimization of molecular weight and
concentration of polymer, types of solvents, salt concentration can
produce a suitable set condition of the ink for respective
applications.
[0095] The gels such as agar, gelatin, agarose, alginic acid,
carrageenan and the like are the products of sol-gel reaction due
to their helix formations. In those cases, the ink made of gelatin
water solution is heated and jetted from an inkjet apparatus to a
cooled sheet, then the landed ink can be set. In a case of gelatin,
it is practically useful because its sol-gel transformation tends
to occur around 25.degree. C. In a case of electrolytic
polysaccharide such as alginic acid, adding calcium ion helps
producing gel. Thus polysaccharide or calcium can be added to
either one of the ink or the burn-off base layer, or vice versa can
make the ink set suitable for respective applications. In a case of
calcium, it hardly affects adversely to the finished product even
the calcium is baked. Agar and agarose can be also used.
[0096] In the present invention, the gelling indicates a status
where fluidity of ink lowers. For instance, a combination of
protogenic polymer such as polyacrylic acid, polyaryl amine,
polyvinyl alcohol, with protophilic polymer such as polyethylene
glycol, polyvinyl pyrrolidone can produce gel. In a case of using
such polymer gel or polymer complex, the percentage composition of
the protogenic polymer and protophilic polymer can be adjusted as
approx. 1:1, so that stable gelling reaction is expected.
Optimization of polymer concentration, ion concentration, and pH
upon request can realize the ink-set condition suitable for the
request.
[0097] In a case of polymer having ligand, which can form complex
as side chain, such as poly(carboxylic acid), polyol and polyamine,
adding polyvalent metal ion can help producing ion. For instance,
polyvinyl alcohol in copper acetate aqueous solution is used as the
burn-off base layer, and the ink including NH.sub.3 functional
group lands on this base layer. Then the landed ink becomes gel
instantaneously. Reaction of hydro-colloid such as alginate, mannan
with bivalent metal ion such as calcium ion also produces gel. In a
case of such gel, chelator such as ethylene diamine tetra-acetate
(EDTA) is added so that calcium ion is removed, whereby the gel
turns into sol again. Arbitrary control of this gelling-soling
reaction can optimize manufacturing methods of various electronic
components suitable for respective applications and products.
[0098] Xanthan gum of polysaccharide, which is used as bodying
agent or gelling agent in food, can be used in this application of
the present invention. Hyaluronic acid can be also used in this
application because of its high water absorbing property. Curdlan
of polysaccharide is not water-soluble but can be gelled at
54.degree. C. and, at 80.degree. C. it is further gelled thermally
irreversible, thus it can be used in this application. As discussed
above, in the case of natural polymer, various gelling reactions
are available. For instance, starch, agar, carageenan, and gelatin
can be gelled by hydrogen bonding (gelling by cooling in
particular). Adding polyvalent metal ion to alginic acid, pectin,
carboxymethyl cellulose, or mannan can produce gel. Methyl
cellulose or hydroxy-propyl cellulose can be gelled by its
hydrophobic interaction (gelled by heating, e.g., alkyl side-chain
of carbon number 6, 12, 16 is added in a quantity of several % to
hydroxy-propyl cellulose, then gelling reaction occurs). Xanthan
gum or hyaluronic acid can be gelled by cooling. Curdlan can be
gelled by heating. Those reactions can be used in the present
invention. Hyaluronic acid made by cosmetic manufacturers or food
manufactures in Japan is available. They manufacture this acid by
fermentation method or extract it from cock's comb.
[0099] In a case of protein, gelatin or collagen can be gelled by
cooling. Egg white albumin, soybean protein or casein can be gelled
by heating (or protein association). Fibrin, elastin or keratin is
possibly gelled by covalent bond. Those gelling reaction can be
also used in the present invention.
[0100] Various materials developed for disposal diapers, sanitary
napkins, skincare, and hair-care can be also used. Polymer
aggregating agent (electrolytic polymer that aggregates fine
particles dispersing in water) can be used in the burn-off base
layer, so that fine particles of the metal or the oxide contained
in the ink landed on the base layer can be flucculated or
precipitated for setting the ink. For such an application, nonion
or anion polymer, cationic polymer and amphoteric polymer are
commercially available. They can be used in the present invention
responsive to respective applications.
[0101] The jet-ink used in the present invention preferably
contains at least one of metal powder, dielectric powder, glass
powder, ceramic powder, ferrite powder, oxide powder in a quantity
of 1 to 80 weight %. If the content is less than 1 weight %, a
predetermined electrical properties sometimes cannot be obtained
after baking. If the content is not less than 81 weight %, ink
sometimes clogs the inkjet printer. A particle diameter of those
powder is preferably ranges from 0.001 .mu.m to 10 .mu.m. If the
diameter is less than 0.001 .mu.m, pieces of powder become too
small, which invites a higher cost, and sometimes a given
electrical property cannot be obtained. If the diameter is not less
than 12 .mu.m, the powder percipitates or flucculates in the
jet-printer, which eventually clogs. The viscosity of jet-ink is
preferably not more than 2 poise. If the viscosity is not less than
2.5 poise, a jet printer is hard to jet the ink, and jets the ink
in dispersed directions. In a case of jetting the ink in dispersed
directions, landing accuracy of the ink on the sheet degrades, so
that the inkjet cannot form a precise pattern.
[0102] Reactive material or organic material containing functional
groups such as carboxylic acid, carboxyl group or amine, they are
to be donors or acceptors proposed by the present invention, is
preferably contained in the ink or the burn-off base layer in a
quantity of not less than 0.01 weight %. If the content is less
than 0.01 weight %, the ink set status required in the present
invention sometimes cannot be obtained.
[0103] When the burn-off base layer is to disappear, the thickness
is preferably not more than 20 .mu.m. If the thickness is not less
than 25 .mu.m, the pattern formed on the base layer slips or
deforms when the base layer disappears. In the case of reaction
produced by difference in pH, the difference is preferably not less
than 0.5. If the difference is less than 0.3, the landed ink
sometimes cannot be gelled.
[0104] The gelling reaction proposed in the present invention is a
phenomenon occurs between plural jet-inks, or jet-ink and a
burn-off base layer, or jet-ink and a substrate supposed to be
printed. The gel per se is preferably an organic substance to be
burnt off. However, as discussed above, metal, oxide, or metal ion
thereof contained in the jet ink or the burn-off base layer reacts
with another organic substance after the landing, and they can be
gelled.
[0105] Industrial Applicability
[0106] A burn-off base layer is formed on unbaked ceramic substrate
such as ceramic green sheet, or laminated ceramic green sheets, or
unbaked ceramic member. This burn-off base layer improves ink
acceptability of the unbaked ceramic substrate particularly for low
viscosity ink such as inkjet, and prevents oozing, draining, uneven
thickness. This structure allows the inkjet to form a precise
pattern. The burn-off base layer is burnt off in the baking step in
the manufacturing process of electronic components, thus it does
not adversely affect the reliability of the electronic component.
Repeating the process of forming the base layer through forming a
pattern by inkjet plural times can produce a three dimensional
structure with ease even its shape is complicated.
* * * * *