U.S. patent application number 13/779939 was filed with the patent office on 2014-08-28 for making multi-layer micro-wire structure.
The applicant listed for this patent is Ronald Steven Cok, John Andrew Lebens, David Paul Trauenicht, Yongcai Wang, Hwei-Ling Yau. Invention is credited to Ronald Steven Cok, John Andrew Lebens, David Paul Trauenicht, Yongcai Wang, Hwei-Ling Yau.
Application Number | 20140242297 13/779939 |
Document ID | / |
Family ID | 51388429 |
Filed Date | 2014-08-28 |
United States Patent
Application |
20140242297 |
Kind Code |
A1 |
Yau; Hwei-Ling ; et
al. |
August 28, 2014 |
MAKING MULTI-LAYER MICRO-WIRE STRUCTURE
Abstract
A method of making a multi-layer micro-wire structure includes
providing a substrate having a surface and forming a plurality of
micro-channels in the surface. A first material composition is
located in a first layer only in each micro-channel and not on the
surface. A second material composition different from the first
material composition is located in a second layer different from
the first layer only in each micro-channel and not on the surface.
The first material composition in the first layer and the second
material composition in the second layer form an electrically
conductive multi-layer micro-wire in each micro-channel.
Inventors: |
Yau; Hwei-Ling; (Rochester,
NY) ; Trauenicht; David Paul; (Rochester, NY)
; Lebens; John Andrew; (Rush, NY) ; Wang;
Yongcai; (Rochester, NY) ; Cok; Ronald Steven;
(Rochester, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yau; Hwei-Ling
Trauenicht; David Paul
Lebens; John Andrew
Wang; Yongcai
Cok; Ronald Steven |
Rochester
Rochester
Rush
Rochester
Rochester |
NY
NY
NY
NY
NY |
US
US
US
US
US |
|
|
Family ID: |
51388429 |
Appl. No.: |
13/779939 |
Filed: |
February 28, 2013 |
Current U.S.
Class: |
427/557 ;
427/108; 427/58 |
Current CPC
Class: |
H01L 51/5215 20130101;
H01J 9/148 20130101; G06F 2203/04112 20130101; H01L 2251/5369
20130101; G06F 2203/04103 20130101; H01J 2211/225 20130101; H05K
3/0011 20130101; H05K 3/46 20130101; H05K 3/467 20130101; H01J
11/22 20130101; H01L 33/60 20130101; H05K 3/42 20130101; B05D 5/12
20130101; C09D 11/52 20130101; G01N 27/403 20130101; H05K 3/107
20130101 |
Class at
Publication: |
427/557 ; 427/58;
427/108 |
International
Class: |
H01B 13/00 20060101
H01B013/00 |
Claims
1. A method of making a multi-layer micro-wire structure,
comprising: providing a substrate having a surface; forming a
plurality of micro-channels in the substrate; locating a first
material composition in a first layer only in each micro-channel
and not on the substrate surface by coating the first material
composition over the substrate surface and micro-channels, removing
the first material composition from the substrate surface and not
the micro-channels, and curing the first material composition into
the first layer; locating a second material composition different
from the first material composition in a second layer different
from and in contact with the first layer only in each micro-channel
and not on the substrate surface by coating the second material
composition over the substrate surface, first layer, and
micro-channels, removing the second material composition from the
substrate surface and not the micro-channels or first layer, and
curing the second material composition into the second layer; and
wherein: the first material composition in the first layer is
electrically conductive and the second material composition in the
second layer is electrically conductive; and the first material
composition in the first layer and the second material composition
in the second layer form an electrically conductive multi-layer
micro-wire in each micro-channel.
2. The method of claim 1, further including forming the plurality
of micro-channels in the substrate surface by: providing an
impressionable layer as part of the substrate; impressing the
impressionable layer with a pattern; and hardening the patterned
impressionable layer.
3. (canceled)
4. The method of claim 1, further including adhering the first
layer to the substrate.
5. The method of claim 4, wherein the first layer is adhered to the
substrate by heating the first layer.
6. The method of claim 4, wherein the first layer is heated by
infrared radiation.
7. The method of claim 1, further including adhering the second
layer to the substrate or to the first layer.
8. The method of claim 7, wherein the second layer is adhered to
the first layer or the substrate by heating the second layer.
9. The method of claim 7, wherein the second layer is heated by
infrared radiation.
10. The method of claim 1, wherein the first material composition
is cured by heating to form the first layer.
11. The method of claim 1, wherein the second material composition
is cured by heating to form the second layer.
12. The method of claim 1, further including locating a layer on a
surface of the first layer, the layer including a material that
controls the surface energy of the first material composition with
respect to the second material composition.
13. The method of claim 1, further including providing the first or
second material compositions as a liquid or as particles within a
liquid carrier.
14. The method of claim 1, further including providing the first or
second material compositions as a powder.
15. The method of claim 1, wherein the first and second material
compositions are located in the micro-channels by: providing a
third material composition having the materials of the first and
second material compositions; locating the third material
composition over the substrate surface and in the micro-channels;
removing the third material composition from the substrate surface
and not the micro-channels; processing the third material
composition to separate the first material composition into the
first layer and the second material composition into the second
layer.
16. The method of claim 15, further including curing the separated
first and second material compositions.
17. The method of claim 15, wherein the third material composition
is separated into the material composition in the first layer and
the second material composition in the second layer by processing
the third material composition with hydrochloric acid.
18. The method of claim 15, further including providing the third
material composition as a liquid or as particles within a liquid
carrier.
19. The method of claim 15, further including providing the third
material composition including a wax.
20. The method of claim 15, further including providing the third
material composition as a powder.
21. (canceled)
22. A method of making a multi-layer micro-wire structure,
comprising: providing a substrate having a surface; forming a
plurality of micro-channels in the substrate; locating a first
material composition in a first layer only in each micro-channel
and not on the substrate surface; locating a second material
composition different from the first material composition in a
second layer different from and in contact with the first layer
only in each micro-channel and not on the substrate surface; and
wherein: the first material composition in the first layer is
electrically conductive and the second material composition in the
second layer is electrically conductive; and the first material
composition in the first layer and the second material composition
in the second layer form an electrically conductive multi-layer
micro-wire in each micro-channel; and the substrate has a
transparency of greater than 50% in the visible range of
electromagnetic radiation and either the first or the second layer
has a transparency and reflectance of less than 50% in the visible
range of electromagnetic radiation.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] Reference is made to commonly-assigned U.S. patent
application Ser. No. ______ filed concurrently herewith, entitled
"Multi-Layer Micro-Wire Structure" by Yau et al, the disclosure of
which is incorporated herein.
FIELD OF THE INVENTION
[0002] The present invention relates to micro-wire electrical
conductors.
BACKGROUND OF THE INVENTION
[0003] Transparent conductors are widely used in the flat-panel
display industry to form electrodes for electrically switching the
light-emitting or light-transmitting properties of a display pixel,
for example in liquid crystal or organic light-emitting diode
displays. Transparent conductive electrodes are also used in touch
screens in conjunction with displays. In such applications, the
transparency and conductivity of the transparent electrodes are
important attributes. In general, it is desired that transparent
conductors have a high transparency (for example, greater than 90%
in the visible spectrum) and a low electrical resistivity (for
example, less than 10 ohms/square).
[0004] Conventional transparent conductors are typically coated on
a substrate to form a patterned layer of a transparent, conductive
material, such as indium tin oxide or other metal oxide. Such
materials are increasingly expensive and relatively costly to
deposit and pattern. Moreover, metal oxides have a limited
conductivity and transparency, and tend to crack when formed on
flexible substrates.
[0005] More recently, transparent electrodes including very fine
patterns of conductive micro-wires have been proposed. For example,
capacitive touch-screens with mesh electrodes including very fine
patterns of conductive elements, such as metal wires or conductive
traces, are taught in U.S. Patent Application Publication No.
2010/0328248 and U.S. Pat. No. 8,179,381, which are hereby
incorporated in their entirety by reference. As disclosed in U.S.
Pat. No. 8,179,381, fine conductor patterns are made by one of
several processes, including laser-cured masking, inkjet printing,
gravure printing, micro-replication, and micro-contact printing.
The transparent micro-wire electrodes include micro-wires between
0.5.mu. and 4.mu. wide and a transparency of between approximately
86% and 96%.
[0006] Conductive micro-wires can be formed in micro-channels
embossed in a substrate, for example as taught in CN102063951,
which is hereby incorporated by reference in its entirety. As
discussed in CN102063951, a pattern of micro-channels can be formed
in a substrate using an embossing technique. Embossing methods are
generally known in the prior art and typically include coating a
curable liquid, such as a polymer, onto a rigid substrate. The
polymer is partially cured (through heat or exposure to light or
ultraviolet radiation) and then a pattern of micro-channels is
embossed (impressed) onto the partially cured polymer layer by a
master having a reverse pattern of ridges formed on its surface.
The polymer is then completely cured. A conductive ink is then
coated over the substrate and into the micro-channels, the excess
conductive ink between micro-channels 60 is removed, for example by
mechanical buffing, patterned chemical electrolysis, or patterned
chemical corrosion. The conductive ink in the micro-channels is
cured, for example by heating. In an alternative method described
in CN102063951, a photosensitive layer, chemical plating, or
sputtering is used to pattern conductors, for example using
patterned radiation exposure or physical masks. Unwanted material
(photosensitive resist) is removed, followed by electro-deposition
of metallic ions in a bath.
[0007] Optical attributes such as transparency, contrast, or
reflectivity are important for display systems. Mechanical concerns
such as flexibility and environmental robustness such as scratch
and chemical resistance are also important, especially for touch
screens designed for interaction with humans. There is a need,
therefore, for improved micro-wire structures that meet these
needs.
SUMMARY OF THE INVENTION
[0008] In accordance with the present invention, a method of making
a multi-layer micro-wire structure comprises:
[0009] providing a substrate having a surface;
[0010] forming a plurality of micro-channels in the surface;
[0011] locating a first material composition in a first layer in
each micro-channel and not on the surface;
[0012] locating a second material composition different from the
first material composition in a second layer different from the
first layer in each micro-channel and not on the surface; and
[0013] wherein the first material composition in the first layer
and the second material composition in the second layer form an
electrically conductive multi-layer micro-wire in each
micro-channel.
[0014] The present invention provides an electrically conductive
micro-wire structure having improved transparency, contrast, or
reflectivity, improved flexibility, and resistance to
scratches.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The above and other features and advantages of the present
invention will become more apparent when taken in conjunction with
the following description and drawings wherein identical reference
numerals have been used to designate identical features that are
common to the figures, and wherein:
[0016] FIG. 1 is a cross section of a multi-layer micro-wire
structure embodiment of the present invention;
[0017] FIGS. 2-10 are cross sections of a multi-layer micro-wire in
a micro-channel illustrating other embodiments of the present
invention;
[0018] FIG. 11 is a plan view of a multi-layer micro-wire
illustrating an embodiment of the present invention;
[0019] FIG. 12 is a schematic illustrating a material composition
in a micro-channel useful in understanding various embodiments of
the present invention; and
[0020] FIG. 13 is a cross section of a multi-layer micro-wire in a
micro-channel illustrating an embodiment of the present
invention;
[0021] FIG. 14A is a cross section of a material composition in a
micro-channel useful for understanding an embodiment of the present
invention;
[0022] FIG. 14B is a cross section of a multi-layer micro-wire in a
micro-channel illustrating an embodiment of the present
invention;
[0023] FIGS. 15-20 are flow charts illustrating various methods of
making the present invention;
[0024] FIG. 21 is a representation of a micrograph illustrating a
micro-channel useful in an embodiment of the present invention;
[0025] FIG. 22 is a schematic illustrating an embodiment of the
present invention; and
[0026] FIGS. 23A and 23B are cross sections of display systems
illustrating an embodiment of the present invention.
[0027] The Figures are not necessarily to scale, since the range of
dimensions in the drawings is too great to permit depiction to
scale.
DETAILED DESCRIPTION OF THE INVENTION
[0028] The present invention is directed toward multi-layer
micro-wire structures formed in a substrate that are capable of
conducting electrical currents. The electrically conductive
micro-wire structures provide improved transparency, contrast, or
reflectivity, improved flexibility, and resistance to
scratches.
[0029] Referring to FIG. 1 in an embodiment of the present
invention, a multi-layer micro-wire structure 5 includes a
substrate 40 having a substrate surface 41. A plurality of
micro-channels 60 are formed in substrate 40. Substrate-surface
open areas 42 on substrate 40 separate micro-channels 60.
Micro-channels 60 extend from substrate surface 41 into substrate
40. A first material composition is located in a first layer 10 in
each micro-channel 60 and not on substrate surface 41 and not in
substrate-surface open areas 42 between micro-channels 60. A second
material composition different from the first material composition
is located in a second layer 20 different from first layer 10 in
each micro-channel 60 and not on substrate surface 41 and not in
substrate-surface open areas 42 between micro-channels 60. The
first material composition in first layer 10 and the second
material composition in second layer 20 form an electrically
conductive multi-layer micro-wire 50 in each micro-channel 60.
[0030] The designation of first or second with respect to material
compositions or layers is arbitrary and does not necessarily
specify order or structure. Thus, depending on the embodiment of
the present invention, first layer 10 is formed on second layer 20
or second layer 20 is formed on first layer 10. In any specific
example or embodiment, the first or second material composition or
layer designations can be reversed without changing the nature of
the invention.
[0031] According to various embodiments of the present invention,
the substrate 40 is any material having a substrate surface 41 in
which micro-channels 60 can be formed. For example, glass and
plastic are suitable materials known in the art from which
substrates 40 can be made into sheets of material having
substantially parallel opposed sides, one of which is substrate
surface 41. In various embodiments, substrate 40 is rigid,
flexible, or transparent. The substrate 40 of the present invention
is large enough for a user to directly interact therewith, for
example with an implement such as a stylus or with a finger or
hand. The substrates of integrated circuits are too small for such
interaction.
[0032] The micro-channel 60 is a groove, trench, or channel formed
in substrate 40 and extending from substrate surface 41 into
substrate 40 and having a cross-sectional width W in a direction
parallel to substrate surface 41 less than 20 microns, for example
10 microns, 5 microns, 4 microns, 3 microns, 2 microns, 1 micron,
or 0.5 microns, or less. In an embodiment, the cross-sectional
depth D of micro-channel 60 is comparable to the width W.
Micro-channels 60 can have a rectangular cross section, as shown.
Other cross-sectional shapes, for example trapezoids, are known and
are included in the present invention. First and second layers 10,
20 can have different depths, for example first layer 10 has a
depth of D1 and second layer 20 has a second depth D2 that is
greater than D1. As used herein, the depth of a layer (first and
second layers 10, 20) or the depth of a multi-layer micro-wire 50
is also the thickness of the layer or micro-wire. The width or
depth of a layer is measured in cross section.
[0033] Multi-layered micro-wires 50 of the present invention are
structured micro-wires and have at least first and second layers
10, 20. Multi-layer micro-wires 50 having more than two layers, for
example three layers, are also contemplated and are included in the
present invention and discussed further below. At least one of
first or second layers 10, 20 of multi-layer micro-wire 50 is
electrically conductive. In an embodiment, more than one layer of
multi-layer micro-wires 50 is electrically conductive, for example
first and second layers 10, are electrically conductive. In
different embodiments, first layer 10 is more electrically
conductive than second layer 20 or second layer 20 is more
electrically conductive than first layer 10. First or second layer
10, 20 can have different optical properties.
[0034] Different materials coated in separate layers over patterned
substrates are known. In contrast, multi-layer micro-wires 50 are
formed in micro-channels 60 and not over the surface of the
substrate 40. Because micro-channels 60 have such a narrow width
and extend into substrate 40, conventional substrate deposition and
patterning methods, for example using sputtering to form a layer
and then coated photo-resist with masked exposure to pattern a
substrate are problematic or expensive. While it is known to form
conventional micro-wires, as discussed above, multi-layer
micro-wires 50 of the present invention are structured multi-layer
micro-wires 50 having at least first and second layers 10, 20. Such
structured multi-layered micro-wires 50 are not known in the prior
art and provide advantages as disclosed herein.
[0035] The first and second material compositions forming first and
second layers 10, 20 are located in micro-channels 60 only, and are
not located on substrate surface 41, for example between
micro-channels 60 in substrate-surface open areas 42. Thus, first
and second layers 10, 20 are found only in micro-channels 60 and
not in substrate surface open areas 42. First or second material
compositions can be provided in one state and then processed into
another state, for example converted from a liquid state into a
solid state, to form a layer. Such conversion can be accomplished
in a variety of ways, for example by drying or heating.
Furthermore, first or second material compositions can include a
set of materials when located and be processed to include a subset
of the set of materials, for example by removing solvents from the
material composition. For example, a material composition including
a solvent is deposited and then processed to remove the solvent
leaving a material composition without the solvent in place. Thus,
according to embodiments of the present invention, a material
composition that is deposited on substrate 40 is not necessarily
the same composition as that found in a processed layer (first or
second layer 10, 20).
[0036] According to various embodiments of the present invention,
the first and second layers 10, 20 of micro-wires 50 have different
electrical, mechanical, optical, or chemical properties. In the
embodiment illustrated in FIG. 1, multi-layer micro-wire 50
includes first layer 10 located farther from substrate surface 41
than second layer 20, second layer 20 is more electrically
conductive than first layer 10, and first layer 10 is more
light-absorbing than second layer 20. In the embodiment illustrated
in FIG. 2, multi-layer micro-wire 50 includes first layer 10
located closer to substrate surface 41 of substrate 40 than second
layer 20, second layer 20 is more electrically conductive than
first layer 10, and first layer 10 is more light-absorbing than
second layer 20.
[0037] Referring to FIG. 3, in an embodiment of the present
invention, substrate 40 has a micro-channel 60 extending from
substrate surface 41 in which multi-layer micro-wire 50 is formed.
Multi-layer micro-wire 50 includes first layer 10, second layer 20,
and a third layer 30. Third layer 30 is formed from a third
material composition located in third layer 30 in each
micro-channel 60 and not on substrate surface 41. Third material
composition, in one embodiment, is different from both the first
and second material compositions or, in another embodiment, is
substantially the same as either the first or second material
composition. In a particular embodiment, third layer 30 is formed
from a third material composition that is substantially the same as
the first material composition so first and third layers 10, 30 are
similar and the first and third material compositions are located
both above and below second layer 20. In an embodiment, second
layer 20 is more electrically conductive than first and third
layers 10, 30, and first and third layers 10, 30 are more
light-absorbing than second layer 20.
[0038] As shown in FIG. 2, first and second layers 10, 20 are in
contact over a substantially flat surface 70. Referring to FIG. 4,
in an embodiment of the present invention, multi-layer micro-wire
50 having first and second layers 10, 20 are in contact over a
substantially curved surface 72. Referring also to FIG. 7,
micro-channel 60 has a four-sided cross section with a
micro-channel top 61 at substrate surface 41, a micro-channel
bottom 63 opposing micro-channel top 61, and micro-channel sides 62
joining micro-channel top 61 to micro-channel bottom 63. As shown
in FIG. 4, first layer 10 extends from locations 11 on
micro-channel sides 62 that are relatively closer to micro-channel
top 61 to a location 12 that is relatively closer to micro-channel
bottom 63. A depth D3 of first layer 10 at micro-channel sides 62
is greater than a depth D4 of first layer 10 at location 12 nearer
micro-channel bottom 63, forming curved surface 72 interfacing
between first layer 10 and second layer 20 so that both first layer
10 and second layer 20 have a variable thickness.
[0039] In the embodiments illustrated in FIGS. 1-4, first and
second layers 10 and 20 are essentially stacked so that second
layer 20 is substantially above first layer 10 with respect to
substrate surface 41 or vice versa. In an alternative embodiment
illustrated in FIGS. 5 and 6, first and second layers 10 and 20 are
at least partially concentric. By partially concentric is meant
that one layer (second layer 20) is not exclusively over or under
another layer (first layer 10). Referring to FIG. 5, multi-layer
micro-wire 50 includes first layer 10 and second layer 20. First
layer 10 is partially beneath second layer 20 (with respect to
substrate surface 41 of substrate 40) and partially at the side of
second layer 20. Thus, first layer 10 is not exclusively over or
under second layer 10 since first layer 10 is also beside second
layer 20. Therefore, in the example of FIG. 5, first layer 10 is
partially concentric with second layer 20.
[0040] Referring to FIG. 6, multi-layer micro-wire 50 includes
first layer 10 and second layer 20. First layer 10 is beneath
second layer 20 (with respect to substrate surface 41 of substrate
40) and also at the side of second layer 20. Third layer 30 is over
second layer 20 and has the same material composition as first
layer 10. In such an embodiment, when the material compositions of
two layers are the same, the layers can be considered to be one
layer. Thus, first layer 10 is not exclusively over or under second
layer 10 since first layer 10 is beside, under, and over second
layer 20.
[0041] In various embodiments, first layer 10 or second layer 20
fills micro-channel 60 and extends to substrate surface 41 (as
shown in FIGS. 1-3). Alternatively, first layer 10 or second layer
20 does not fill micro-channel 60 and extends beneath substrate
surface 41 (as shown in FIG. 4). As shown in FIG. 8, in another
embodiment of the present invention, first layer 10 or second layer
20 extends from micro-channel 60 beyond substrate surface 41 to
form an extended surface 74 of multi-layer micro-wire 50 formed in
substrate 40.
[0042] In various embodiments, first or second material
compositions can include metal nano-particles. The metal
nano-particles can be sintered to form a metallic electrical
conductor. The metal can be silver or a silver alloy or other
metals, such as tin, tantalum, titanium, gold, or aluminum, or
alloys thereof. First or second material compositions can include
light-absorbing materials such as carbon black, a dye, or a
pigment. In one embodiment, the first material composition includes
carbon black, a black dye, or a black pigment and the second
material composition includes silver nano-particles.
[0043] In other embodiments, the second material composition
includes a material in the first material composition or the first
material composition includes a material in the second material
composition. Alternatively, the first material composition can
include two different materials in a first ratio and the second
material composition can include the same two materials in a second
ratio different from the first ratio. For example, the first
material composition can include a relatively high percentage of a
light-absorbing material such as carbon black and a relatively low
percentage of metal nano-particles. In contrast, the second
material composition can include a relatively low percentage of a
light-absorbing material such as carbon black and a relatively high
percentage of metal nano-particles. Note that both first and second
layers, 10, 20 formed from the first and second material
compositions, respectively, can be electrically conductive although
in different amounts. As is known, carbon black itself can be
conductive.
[0044] As noted above, multi-layer micro-wires 50 of the present
invention can include more than two layers. Referring to FIG. 9, in
one embodiment, the multi-layer micro-wire 50 including first and
second layers 10, is formed in substrate 40. A surface-energy layer
80 is located between first and second layers 10, 20. Surface
energy layer 80 includes a material that controls the surface
energy of the first material composition with respect to the second
material composition. Thus, surface energy layer 80 can enable the
first material composition to wet the second material composition
in second layer 20. Surface-energy layer 80 can be deposited over
second layer 20 before first layer 10 is located in micro-channel
60, for example by coating, and can, but does not necessarily,
extend over substrate surface 41 of substrate 40. Alternatively,
the surface of second layer 20 can be treated, for example with a
plasma treatment, to modify its surface-energy characteristics and
form the surface-energy layer 80.
[0045] In another embodiment, first layer 10 is adhered to
substrate 40, second layer 20 is adhered to substrate 40, or first
layer 10 is adhered to second layer 20. Adhesion between substrate
40 (for example in micro-channel 60 on either or both the
micro-channel sides or bottom) is improved with an adhesion layer
82. Adhesion layer 82 can be located between first layer 10 and
substrate 40 or between second layer 20 and substrate 40 (not
shown). Adhesion layer 82 promotes adhesion between first layer 10
and substrate 40 or second layer 20 and substrate 40, or between
first and second layers 10, 20. Adhesive materials are known in the
art and can be coated or deposited. In an embodiment, adhesive
materials are selected to complement first layer 10, second layer
20, or substrate 40.
[0046] First layer 10 or second layer 20 can have a color or be
reflective. U.S. Patent Application Publication No. 2008/0257211
discloses a variety of metallic colored inks and its contents are
hereby incorporated by reference.
[0047] Referring further to FIG. 10, multi-layer micro-wire 50
including first and second layers 10, 20 formed in substrate 40 can
have a width W less than a depth or thickness D so that multi-layer
micro-wire 50 has an aspect ratio (D/W) greater than one.
Multi-layer micro-wire 50 can be covered with a protective layer 44
to protect from scratches or other environmental damage, including
mechanical or chemical damage. Protective layer 44 can be formed
over just multi-layer micro-wire 50 (not shown) or over a more
extensive portion of substrate surface 41 (as shown).
[0048] Referring to the top view of FIG. 11, a layer (second layer
20) need not continuously cover another layer, (first layer 20) in
multi-layer micro-wire 50. In an embodiment, first layer 10
completely covers micro-channel 60 surface or second layer 20 or
second layer 20 completely covers micro-channel 60 surface or first
layer 10. Alternatively, first layer 10 covers only a portion of
micro-channel 60 surface or second layer 20 or second layer 20
covers only a portion of micro-channel 60 surface or first layer
10. Micro-channel 60 surface is micro-channel sides 62 and
micro-channel bottom 63 (as illustrated in FIG. 7).
[0049] In various embodiments of the present invention, multi-layer
micro-wire 50 has a width less than or equal to 10 microns, 5
microns, 4 microns, 3 microns, 2 microns, or 1 micron. Likewise,
micro-channel 60 has a width less than or equal to 20 microns, 10
microns, 5 microns, 4 microns, 3 microns, 2 microns, or 1 micron.
In some embodiment, multi-layer micro-wire 50 can fill
micro-channel 60; in other embodiments multi-layer micro-wire 50
does not fill micro-channel 60.
[0050] In an embodiment, first or second layer 10, 20 is solid.
Referring to FIG. 13, in another embodiment, first or second layer
10, 20 is porous. Referring also to FIG. 12, a material composition
90 can include conductive particles 92 (or light-absorbing
particles) in a liquid carrier 94 (for example an aqueous
solution). Liquid carrier 94 can be located in micro-channels 60
and heated or dried to remove liquid carrier 94, leaving a porous
assemblage of conductive particles 92 that can be sintered to form
a porous electrical conductor in a layer. First and second layers
10, 20 having different conductive particles 92 and light-absorbing
particles 96 can overlap to form a layer (third layer 30) including
both first and second material compositions, as shown in FIG. 13.
Thus, in an embodiment, first and second layers 10, 20 are
processed to change their material compositions, and also to form
the third layer 30 having a material composition that includes
materials from the first and second material compositions.
[0051] Referring to the example of FIGS. 14A and 14B, a material
composition having conductive particles 92 and light-absorbing
particles 96 in the liquid carrier 94 is located in the
micro-channel 60. The material composition is processed, for
example by drying and treatment with hydrochloric acid, to remove
liquid carrier 94, agglomerate conductive particles 92 and move
light-absorbing particles 96 outside the area of agglomerated
conductive particles 92 forming a light-absorbing first layer 10
concentric with a conductive second layer 20. Conductive particles
92 can be, for example, silver nano-particles and light-absorbing
particles 96 can be, for example, carbon black, a dye, or pigments.
The liquid carrier 94 can be an aqueous solution and can include
surfactants, humectants, thickeners, adhesives and other active
chemicals. Using a commercial dye and silver nano-particles, the
material composition of FIG. 14A has been processed with HCl and
heat to form the layer structure of FIG. 14B, resulting in the
conductive second layer 20. Although, for clarity, light-absorbing
particles 96 are illustrated in a concentric ring around
light-absorbing particles 96 in FIG. 14B, in practice first and
second layers 10, 20 can overlap or intermingle somewhat, and such
structures are included in the present invention. In embodiments of
the present invention, first and second layers 10, 20 can overlap
or intermingle where first and second layers 10, 20, interface,
possibly forming a third layer (not shown), or have contacting
surfaces, either straight or curved.
[0052] Referring to FIG. 15, a method of making the multi-layer
micro-wire structure 5 according to an embodiment of the present
invention includes providing (Step 200) a first material
composition, providing (Step 202) a second material composition
different from the first material composition, and providing (Step
204) the substrate 40 having the substrate surface 41. A plurality
of micro-channels 60 are formed (Step 205) in substrate surface 41.
The first material composition is located (Step 210) in the first
layer 10 in each micro-channel 60 and not on substrate surface 41
and is optionally processed (Step 230) to form first layer 10. The
amount of the first material composition is selected so that, when
the first material composition is located and processed in
micro-channel 60, first layer 10 does not fill micro-channel 60.
The second material composition is located (Step 220) in a second
layer 20 different from first layer 10 in each micro-channel 60 and
not on substrate surface 41 and is optionally processed (Step 231)
to form second layer 20. First and second layers 10, 20 can, but
need not, fill micro-channel 60 or extend above substrate surface
41 (FIGS. 2, 4, 8). The amount of the second material composition
is selected to fill micro-channel 60 to the desired extent. The
optionally processed first material composition in first layer 10
and the optionally processed second material composition in second
layer 20 form an electrically conductive multi-layer micro-wire 50
in each micro-channel 60.
[0053] The first or second material compositions can be provided
(Steps 200, 202) as a liquid or as particles within a liquid
carrier (as illustrated in FIG. 12). Alternatively, the first or
second material compositions can be provided (Steps 200, 202) as a
powder. The first or second material compositions can be provided
together or before or after each other in separate process
steps.
[0054] In a further method, referring to FIG. 16, the plurality of
micro-channels 60 is formed (Step 205) (corresponding to (Step 205)
of FIG. 15) in substrate 40 by providing (Step 206) an
impressionable layer as part of substrate 40. Referring also to
FIG. 7, substrates 40 can include multiple layers having different
chemical or mechanical properties, for example a polymer layer 48
formed or located on a glass substrate 46. Substrate 40 can be
provided in one state and then processed into another state. In
particular, substrate 40 can be initially provided as the glass
substrate 46 or plastic layer on which a partially cured and
impressionable polymer layer 48 is formed, for example by coating.
The impressionable polymer layer 48 is impressed (Step 207) with a
pattern forming micro-channels 60, and then subsequently hardened
(Step 208) for example by curing into a more rigid state forming
the patterned polymer layer 48. Curing can be accomplished by
heating or electromagnetic radiation, for example exposure to
ultra-violet light. Suitable curable materials are known in the
art. Alternatively, substrate 40 can be provided as a glass or
plastic layer in which micro-channels 60 are etched.
[0055] Referring to FIG. 17, a method of the present invention is
illustrated in more detail. As shown in FIG. 17, locating (Step
210) a first material composition in micro-channels 60
(corresponding to Step 210 of FIG. 15) can be implemented by
coating (Step 212) a first material composition over the provided
substrate 40. Excess first material composition is removed (Step
213) and the remaining first material composition is optionally
adhered 214 to substrate 40. The first material composition is
cured (Step 216) to form first layer 10. Curing (Step 216) the
first material composition and adhering (Step 214) the first
material composition can be done in a common process step or
separate process steps. A surface-energy layer is optionally coated
(Step 217) over first layer 10 to enhance wetting of first layer 10
when substrate 40 is coated (Step 222) with the second material
composition. The coated layer can include a material that controls
the surface energy of the first material composition with respect
to the second material composition, for example to enhance wetting
of one material composition over a layer. Excess second material
composition is removed (Step 223) and the remaining second material
composition is optionally adhered (Step 224) to substrate 40 or
first layer 10, or both. The second material composition is cured
(Step 226) to form second layer 20. Curing (Step 226) the second
material composition and adhering (Step 224) the second material
composition can be done in a common process step or separate
process steps.
[0056] Curing material compositions to form layers (first or second
layers 10, 20) or adhering the layers to each other or substrate 40
(Steps 214, 216, 224, 226) can be done by drying or heating. In
particular, if micro-channel 60 is formed in the polymer layer 48,
heating the polymer layer 48 slightly can soften the polymer so
that particles, for example black pigment or carbon black particles
or conductive particles, in the first or second material
compositions can adhere to the polymer. Such heating can be done by
convective heating (putting substrate 40 into an oven) or by
infrared radiation. Heating with infrared radiation has the
advantage that light-absorbing particles, for example black
particles, differentially absorb the infrared radiation and heat up
more than substrate 40 (that can be transparent), thus providing a
more efficient adhesion or drying process for a material
composition. Adhesion of first or second layers 10, 20 to substrate
40 or to each other is advantageous because such adhered layers are
more resistant to mechanical abrasion and are thus more
environmentally robust.
[0057] Referring to FIG. 18, in yet another embodiment of the
present invention, the first and second material compositions are
located in micro-channels 60 by providing (Step 201) a third
material composition having the materials of the first and second
material compositions and forming (Step 205) micro-channels 60 in
substrate 40. The third material composition is located (Step 211)
over substrate surface 41 and in micro-channels 60, for example by
coating. Excess third material composition, if any, is removed
(Step 215) from substrate surface 41 and not micro-channels 60. The
third material composition is processed (Step 218) to separate
(Step 219) the first material composition into first layer 10 and
the second material composition into second layer 20, for example
as illustrated in FIGS. 14A and 14B. The first and second material
compositions can be cured to form first and second layers 10, 20 as
a part of the separation process (Step 219) or as a separate step.
In various embodiments of the present invention, curing and
separation process steps are done with heat, drying, or
hydrochloric acid treatment or a combination.
[0058] As noted above with respect to the first or second material
compositions, the third material composition can be provided (Step
201) as a liquid or as particles within a liquid carrier (as
illustrated in FIG. 12). Alternatively, the third material
composition can be provided (Step 201) as a powder. Referring to
FIG. 19, particles are provided (Step 250) and a carrier is
provided (Step 255). The particles and carrier are combined to form
(Step 260) a material composition for example providing (Steps 200,
201, 202) the first, second, or third material composition.
Alternatively, referring to FIG. 20, particles are provided (Step
270) as a powder. Multiple materials can be provided and mixed in
the powder and the mixture can then serve as a material
composition, for example providing (Steps 200, 201, 202) the first,
second, or third material composition.
[0059] The third material composition can include a wax that, when
processed can separate to form a part of either first or second
layers 10, 20, and provide some resistance to mechanical or
chemical environmental abuse.
[0060] Conductive ink formulations useful for the present invention
are commercially available, as are substrates, substrate coating
methods, and micro-patterning methods for forming micro-channels.
Curable polymer layers are well known as are method for coating,
patterning, and curing them. Light-absorbing materials are also
known and can be made into coatable material compositions using
techniques known in the chemical arts.
[0061] For example, it has been demonstrated that multi-layer
micro-wires 50 can be made in the substrate surface 41 embossed
with micro-channels 60 by coating substrate 40 with a conductive
ink including dyes or immersing substrate 40 in a bath of
conductive ink including dyes, removing excess material not in
micro-channels 60, and then processing substrate 40 and conductive
ink with HCl and heat. In another example, a print master (for
example a flexographic printing plate) having a relief pattern is
coated with a conductive ink and the pattern transferred to a
substrate multiple times.
[0062] FIG. 21 illustrates a substrate 40 useful for the present
invention having a pattern of 5.mu.-wide micro-channels 60 embossed
therein.
[0063] Electrically conductive multi-layer micro-wire structures 5
and methods of the present invention are useful for making
electrical conductors and busses for transparent micro-wire
electrodes and electrical conductors in general, for example as
used in busses. A variety of micro-wire patterns can be used and
the present invention is not limited to any one pattern.
Multi-layer micro-wires 50 can be spaced apart, form separate
electrical conductors, or intersect to form a mesh electrical
conductor in substrate 40 (as illustrated in FIG. 21, discussed
further below). Micro-channels 60 can be identical or have
different sizes, aspect ratios, or shapes. Similarly, multi-layer
micro-wires 50 can be identical or have different sizes, aspect
ratios, or shapes. Multi-layer micro-wires 50 can be straight or
curved.
[0064] Substrate 40 can be a rigid or a flexible substrate made of,
for example, a glass or polymer material, can be transparent, and
can have opposing substantially parallel and extensive surfaces.
Substrates 40 can include a dielectric material useful for
capacitive touch screens and can have a wide variety of
thicknesses, for example 10 microns, 50 microns, 100 microns, 1 mm,
or more. In various embodiments of the present invention,
substrates 40 are provided as a separate structure or are coated on
another underlying substrate, for example by coating a polymer
substrate layer on an underlying glass substrate. Such substrates
40 and their methods of construction are known in the prior art.
Substrate 40 can be an element of other devices, for example the
cover or substrate of a display or a substrate, cover, or
dielectric layer of a touch screen. According to embodiments of the
present invention, multi-layer micro-wires 50 extend across at
least a portion of substrate 40 in a direction parallel to
substrate surface 41 of substrate 40.
[0065] Electrically conductive micro-layer micro-wire structures 5
of the present invention are useful, for example in touch screens
such as projected-capacitive touch screens that use transparent
micro-wire electrodes and in displays. Electrically conductive
multi-layer micro-wire structures 5 can be located in areas other
than display areas, for example in the perimeter of the display
area of a touch screen, where the display area is the area through
which a user views a display.
[0066] When used in display systems, micro-layer micro-wires 50 of
the present invention provide an advantage in that light-absorbing
layers can reduce reflection from substrate surface 41, thereby
improving the contrast of a display system. At the same time, the
conductive layers provide electrical conduction useful for
transmitting electrical signals or forming electrical fields.
Referring to FIG. 22, integrated circuit controllers 130 or power
supplies electrically connected with electrical wires 132 to
multi-layer micro-wires 50 provide electrical energy to multi-layer
micro-wire 50. Multi-layer micro-wire 50 operates to conduct
electricity or form an electrical field along the length of
multi-layer micro-wire 50.
[0067] In an embodiment of the present invention, for example as
illustrated in FIGS. 23A and 23B, first layer 10 can be reflective
and third layer 30 can be light-absorbing. Second layer 20 is
electrically conductive. As shown in FIGS. 23A and 23B, a display
100 emits light 120 that is reflected from first layer 10,
reflected again from a back layer (an electrode as is commonly
found in OLED devices of the prior art or a backlight as is
commonly found in transmissive LCD devices of the prior art), and
then emitted. In contrast, ambient light 110 is absorbed by
light-absorbing third layer 30. Thus, because ambient light
reflection is reduced and emitted light is increased, the
arrangement of FIG. 20A improves the contrast of displays. As shown
in FIG. 23A, multi-layer micro-wire structure 5 has substrate
surface 41 on the side of substrate 40 opposite display 100 with
light-absorbing first layer 10 at the bottom of micro-channel 60.
In FIG. 23B, multi-layer micro-wire structure 5 is reversed so that
substrate surface 41 is adjacent display 100 with light-absorbing
first layer 10 at the top of micro-channel 60.
[0068] In an alternative embodiment, both first and third layers
10, 30 are light-absorbing. In other embodiments, a special
reflective layer is omitted since metals (for example in a
conductive layer) are quite reflective and only a light-absorbing
layer is used in combination with a conductive layer (as
illustrated in FIGS. 1 and 2).
[0069] Conductive inks including metallic particles are known in
the art. In useful embodiments, the conductive inks include
nano-particles, for example silver, in a carrier fluid such as an
aqueous solution. The carrier fluid can include surfactants that
reduce flocculation of the metal particles. Once deposited, the
conductive inks are cured, for example by heating. The curing
process drives out the solution and sinters the metal particles to
form a metallic electrical conductor. In other embodiments, the
conductive inks are powders that are pattern-wise transferred to a
substrate and cured or are powders coated on a substrate and
pattern-wise cured. Conductive inks are known in the art and are
commercially available.
[0070] In any of these cases, conductive inks or other conducting
materials are conductive after they are cured and any needed
processing completed. Deposited materials are not necessarily
electrically conductive before patterning or before curing. As used
herein, a conductive ink is a material that is electrically
conductive after any final processing is completed and the
conductive ink is not necessarily conductive at any other point in
multi-layer micro-wire 50 formation process.
[0071] Substrate 40 of the present invention can include any
material capable of providing a supporting surface on which
multi-layer micro-wires 50 can be formed and patterned. Substrates
such as glass, metal, or plastic can be used and are known in the
art together with methods for providing suitable surfaces. In a
useful embodiment, substrate 40 is substantially transparent, for
example having a transparency of greater than 90%, 80% 70% or 50%
in the visible range of electromagnetic radiation.
[0072] A conductive layer of multi-layer micro-wires 50 can be
metal, for example silver, gold, aluminum, nickel, tungsten,
titanium, tin, or copper or various metal alloys including, for
example silver, gold, aluminum, nickel, tungsten, titanium, tin, or
copper. Multi-layer micro-wires 50 can include a thin metal layer
composed of highly conductive metals such as gold, silver, copper,
or aluminum. Other conductive metals or materials can be used.
Alternatively, multi-layer micro-wires 50 can include cured or
sintered metal particles such as nickel, tungsten, silver, gold,
titanium, or tin or alloys such as nickel, tungsten, silver, gold,
titanium, or tin. Conductive inks can be used to form multi-layer
micro-wires 50 with pattern-wise deposition or pattern-wise
formation followed by curing steps. Other materials or methods for
forming multi-layer micro-wires 50 can be employed and are included
in the present invention.
[0073] In an example and non-limiting embodiment of the present
invention, each multi-layer micro-wire 50 is from 5 microns wide to
one micron wide and is separated from neighboring micro-wires 50 by
a distance of 20 microns or less, for example 10 microns, 5
microns, 2 microns, or one micron.
[0074] Methods and device for forming and providing substrates,
coating substrates, patterning coated substrates, or pattern-wise
depositing materials on a substrate are known in the
photo-lithographic arts. Likewise, tools for laying out electrodes,
conductive traces, and connectors are known in the electronics
industry as are methods for manufacturing such electronic system
elements. Hardware controllers for controlling touch screens and
displays and software for managing display and touch screen systems
are all well known. All of these tools and methods can be usefully
employed to design, implement, construct, and operate the present
invention. Methods, tools, and devices for operating capacitive
touch screens can be used with the present invention.
[0075] The present invention is useful in a wide variety of
electronic devices. Such devices can include, for example,
photovoltaic devices, OLED displays and lighting, LCD displays,
plasma displays, inorganic LED displays and lighting,
electrophoretic displays, electrowetting displays, dimming mirrors,
smart windows, transparent radio antennae, transparent heaters and
other touch screen devices such as resistive touch screen
devices.
[0076] The invention has been described in detail with particular
reference to certain embodiments thereof, but it will be understood
that variations and modifications can be effected within the spirit
and scope of the invention.
PARTS LIST
[0077] D depth [0078] D1 first layer depth [0079] D2 second layer
depth [0080] D3 depth [0081] D4 depth [0082] W width [0083] 5
multi-layer micro-wire structure [0084] 10 first layer [0085] 11
location [0086] 12 location [0087] 20 second layer [0088] 30 third
layer [0089] 40 substrate [0090] 41 substrate surface [0091] 42
substrate-surface open area [0092] 44 protective layer [0093] 46
glass substrate [0094] 48 polymer layer [0095] 50 multi-layer
micro-wire [0096] 60 micro-channel [0097] 61 micro-channel top
[0098] 62 micro-channel side [0099] 63 micro-channel bottom [0100]
70 flat surface [0101] 72 curved surface [0102] 74 extended surface
[0103] 80 surface-energy layer [0104] 82 adhesion layer [0105] 90
material composition [0106] 92 conductive particles [0107] 94
carrier [0108] 96 light-absorbing particles [0109] 100 display
[0110] 110 ambient light [0111] 120 emitted light [0112] 130
integrated circuit controller [0113] 132 electrical wire [0114] 200
provide first material composition step [0115] 201 provide third
material composition step [0116] 202 provide second material
composition step [0117] 204 provide substrate step [0118] 205 form
micro-channels step [0119] 206 provide impressionable layer step
[0120] 207 impress impressionable layer with pattern step [0121]
208 harden impressionable layer step [0122] 210 locate first
material step [0123] 211 located third material step [0124] 212
coat substrate with first material step [0125] 213 remove excess
first material step [0126] 214 optional adhere first material to
substrate step [0127] 215 optional remove excess third material
step [0128] 216 cure first material step [0129] 217 optional coat
surface-energy layer step [0130] 218 process third material step
[0131] 219 separate first and second materials step [0132] 220
locate second material step [0133] 222 coat substrate with second
material step [0134] 223 remove excess second material step [0135]
224 optional adhere second material to first layer step [0136] 226
cure second material step [0137] 230 optional process first
material composition step [0138] 231 optional process second
material composition step [0139] 250 provide particles step [0140]
255 provide carrier step [0141] 260 form material composition step
[0142] 270 provide particles step
* * * * *