U.S. patent application number 12/722891 was filed with the patent office on 2010-08-19 for electrically conductive composition.
Invention is credited to Corina Prent, Peter Adrianus Van Veen.
Application Number | 20100209599 12/722891 |
Document ID | / |
Family ID | 40452284 |
Filed Date | 2010-08-19 |
United States Patent
Application |
20100209599 |
Kind Code |
A1 |
Van Veen; Peter Adrianus ;
et al. |
August 19, 2010 |
Electrically Conductive Composition
Abstract
An electrically conductive composition comprising a binder and
filler particles in which at least a portion of the particles are
silver-plated. In one embodiment the composition comprises a binder
such as a polyurethane, electrically conductive filler particles,
silver-plated filler particles and solvent.
Inventors: |
Van Veen; Peter Adrianus;
(St. Netherlands, NL) ; Prent; Corina; (Steenwijk,
NL) |
Correspondence
Address: |
Henkel Corporation
10 Finderne Avenue
Bridgewater
NJ
08807
US
|
Family ID: |
40452284 |
Appl. No.: |
12/722891 |
Filed: |
March 12, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/US2007/078334 |
Sep 13, 2007 |
|
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12722891 |
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Current U.S.
Class: |
427/126.1 ;
252/503; 252/513; 252/514; 977/773 |
Current CPC
Class: |
C08K 3/08 20130101; H01B
1/22 20130101; H05K 3/12 20130101; C09D 5/24 20130101; C09D 7/62
20180101; C08K 9/02 20130101; H05K 2201/0218 20130101; C08L 75/04
20130101; H05K 1/095 20130101; C08L 75/04 20130101; C08L 2666/14
20130101; C08L 75/04 20130101; C08L 2666/16 20130101; C08L 75/04
20130101; C08L 2666/04 20130101 |
Class at
Publication: |
427/126.1 ;
252/514; 252/513; 252/503; 977/773 |
International
Class: |
B05D 5/12 20060101
B05D005/12; H01B 1/22 20060101 H01B001/22; H01B 1/02 20060101
H01B001/02; H01B 1/24 20060101 H01B001/24 |
Claims
1. An electrically conductive composition comprising a binder, and
filler particles having a core plated with silver, wherein said
composition has a sheet resistivity of less than about 0.100
Ohm/square/25 micron.
2. The conductive composition of claim 1, wherein the core is
selected from the group consisting of copper, nickel, palladium,
carbon black, carbon fiber, graphite, aluminum, indium tin oxide,
glass, polymers, antimony doped tin oxide, silica, alumina, fiber,
clay, and mixtures thereof.
3. The conductive composition of claim 2, wherein the core is
copper.
4. The conductive composition of claim 1, wherein the binder is
selected from the group consisting of polyurethane elastomers,
polyesters, phenolic resins, acrylic polymers, acrylic block
copolymers, acrylic polymers having tertiary-alkyl amide
functionality, polysiloxane polymers, polystyrene copolymers,
polyvinyl polymers, divinylbenzene copolymers, polyetheramides,
polyvinyl acetals, polyvinyl butyrals, polyvinyl acetols, polyvinyl
alcohols, polyvinyl acetates, polyvinyl chlorides, methylene
polyvinyl ethers, cellulose acetates, styrene acrylonitriles,
amorphous polyolefins, thermoplastic urethanes, polyacrylonitriles,
ethylene vinyl acetate copolymers, ethylene vinyl acetate
terpolymers, functional ethylene vinyl acetates, ethylene acrylate
copolymers, ethylene acrylate terpolymers, ethylene butadiene
copolymers and/or block copolymers, styrene butadiene block
copolymers, and mixtures thereof.
5. The conductive composition of claim 4, wherein the binder is
selected from the group consisting of polyurethane elastomers,
polyesters, phenolic resins, copoloymer of polyvinylalcohol,
polyvinylacetate and polyvinylchloride, and mixtures thereof.
6. The conductive composition of claim 1, wherein the binder is
selected from the group consisting of phenolics, urethanes, phenoxy
resins, polyesters, epoxies, melamines and mixtures thereof.
7. The conductive composition of claim 6, wherein the binder is
phenolic resins.
8. The conductive composition of claim 1, wherein the composition
further comprising electrically conductive filler material selected
from the group consisting of silver, copper, gold, palladium,
platinum, nickel, gold or silver-coated nickel, carbon black,
carbon fiber, graphite, aluminum, indium tin oxide, silver coated
copper, silver coated aluminum, metallic coated glass spheres,
metallic coated filler, metallic coated polymers, silver coated
fiber, silver coated spheres, antimony doped tin oxide, conductive
nanospheres, nano silver, nano aluminum, nano copper, nano nickel,
carbon nanotubes or mixtures thereof.
9. The conductive composition of claim 1, wherein the composition
further comprising surface active agents, surfactants, wetting
agents, antioxidants, thixotropes, reinforcement materials, silane
functional perfluoroether, phosphate functional perfluoroether,
silanes, titanates, wax, phenol formaldehyde, air release agents,
flow additives, adhesion promoters, rheology modifiers,
surfactants, spacer beads or mixtures thereof.
10. The conductive composition of claim 1, wherein the filler
particles comprise in the range of about 20 to about 70 weight
percent of the composition.
11. The conductive composition of claim 1, wherein the binder
comprises in the range of about 2 to about 40 weight percent of the
composition.
12. The conductive composition of claim 8, wherein the electrically
conductive filler material comprise in the range of up to about 40
weight percent of the composition.
13. An electrically conductive composition comprising a
polyurethane elastomer, one or more silver plated copper particles
and at least one solvent.
14. An electronic device comprising the electrically conductive
composition of claim 1.
15. A process for making or forming an electronic device with the
conductive composition of claim 1 comprising applying the
conductive composition by dispensing, stencil, screen rotogravure
or flexo printing onto a substrate to form conductive tracts or
electronic circuitry, and curing and/or drying said conductive
composition at about 120.degree. C. for about 10 minutes.
16. A process for making or forming an electronic device with the
conductive composition of claim 13 comprising applying the
conductive composition by dispensing, stencil, screen rotogravure
or flexo printing onto a substrate to form conductive tracts or
electronic circuitry, and curing and/or drying said conductive
composition at about 120.degree. C. for about 10 minutes.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of International
Application No. PCT/US2007/078334 filed Sep. 13, 2007, the contents
of which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to an electrically conductive
composition containing silver-plated filler particles.
BACKGROUND OF THE INVENTION
[0003] Silver is utilized as an electrically conductive filler in
many commercially available electrically conductive coatings, and
encapsulants because its oxide is electrically conductive, and
therefore, silver filled systems encounter little or no loss of
conductivity during high temperature curing, aging, or other
conditions under which the silver may be oxidized. A disadvantage
of the use of silver is its high cost and the risk of silver
migration within the system.
[0004] The high level of conductivity and low resistance provided
by entirely silver-filler based products are not necessary for all
conductive material applications. Some applications do not require
such high levels of conductivity and low resistance. Copper is
another conductive material that may be utilized because it is
capable of being processed in forms similar to those in which
silver is available, i.e., in powder, dendritic and flake form. The
main disadvantage of copper is that its oxide is not conductive,
and any surface copper oxide formed during drying or curing limits
the conductivity of the system even if close interparticle contact
is created. Likewise, many other materials that provide electrical
conductivity oxidize under the conditions necessary for formation
of a conductive coating.
[0005] There continues to be a need in the art for a more
economical electrically conductive composition. The present
invention addresses this need.
SUMMARY OF THE PRESENT INVENTION
[0006] The present invention provides an electrically conductive
composition comprising a binder, filler particles, in which at
least a portion of the filler particles are silver-plated, and
optionally, solvent. With the use of silver-plated fillers, the
sheet resistivity of the composition is lower than 0.100
Ohm/square/25 micron.
[0007] Another embodiment provides electronic devices manufactured
using the electrically conductive composition of the invention.
[0008] Still another embodiment is directed to a process of making
or forming an electronic device using the electrically conductive
composition of the invention. The process comprises dispensing, for
example, by stencil, screen, rotogravure or flexo printing, the
electrically conductive composition of the invention onto a
substrate to form conductive tracts or electronic circuitry, and
then curing and/or drying the composition to obtain conductivity.
Exemplary electronic devices that might use these electrically
conductive compositions encompass computers and computer equipment,
such as printers, fax machines, scanners, keyboards and the like;
household appliances; medical sensors; automotive sensors and the
like; and personal electronic devices, such as telephones, mobile
phones, calculators, remote controls, cameras, CD-players,
DVD-players, cassette tape recorders and the like.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0009] The binder component of the electrically conductive coating
or encapsulant will comprise a thermoplastic system, a thermoset
system or a mixture of thermoset and thermoplastic systems.
[0010] The thermoplastic system of the binder component is either a
functional or a non-functional thermoplastic polymer. Suitable
thermoplastic polymers include, but are not limited to,
polyurethane elastomers, polyesters, phenolic resins, acrylic
polymers, acrylic block copolymers, acrylic polymers having
tertiary-alkyl amide functionality, polysiloxane polymers,
polystyrene copolymers, polyvinyl polymers, divinylbenzene
copolymers, polyetheramides, polyvinyl acetals, polyvinyl butyrals,
polyvinyl acetols, polyvinyl alcohols, polyvinyl acetates,
polyvinyl chlorides, methylene polyvinyl ethers, cellulose
acetates, styrene acrylonitriles, amorphous polyolefins,
thermoplastic urethanes, polyacrylonitriles, ethylene vinyl acetate
copolymers, ethylene vinyl acetate terpolymers, functional ethylene
vinyl acetates, ethylene acrylate copolymers, ethylene acrylate
terpolymers, ethylene butadiene copolymers and/or block copolymers,
styrene butadiene block copolymers, and mixtures thereof.
Commercially available binder that may be utilized is ESTANE 5703P,
which is a polyester-type thermoplastic polyurethane available from
Noveon, Ohio, USA; PKHC, which is a phenoxy resin available from
Inchem, South Carolina, USA; and UCAR VAGH, which is a copolymer of
polyvinylalcohol, polyvinylacetate and polyvinylchloride
commercially available from the Dow Chemical Company.
[0011] The thermoset system of the binder component is either a
functional or a non-functional thermoset polymer. Suitable
thermoset polymers include, but are not limited to, phenolics,
urethanes, phenoxy resins, polyesters, epoxies, melamines and
mixtures thereof. One commercially available binder that may be
utilized is Bakelite Hartz 9132KP, which is a phenolic resin
commercially available from Bakelite.
[0012] The total binder content is typically in the range of about
2 to about 50 weight percent of the composition and preferably in
the range of about 2 to about 40 weight percent of the
composition.
[0013] One or more silver-plated fillers are utilized in the
composition. The core of the silver-plated fillers can be
electrically conductive or electrically non-conductive. A
combination of silver-plated fillers, with electrically conductive
core and with electrically non-conductive core, may be used.
Exemplary cores include, but are not limited to, copper, nickel,
palladium, carbon black, carbon fiber, graphite, aluminum, indium
tin oxide, glass, polymers, antimony doped tin oxide, silica,
alumina, fiber, clay, and mixtures thereof.
[0014] In one embodiment the core of the silver-plated filler
particle is copper. The silver content of the silver-plated filler
must be sufficient to provide adequate electrical conductivity and
is typically in the range of about 0.2 to about 25 weight percent
of the silver-plated filler.
[0015] The one or more silver-plated filler particles comprise in
the range of about 1 to about 99 weight percent of the composition
and preferably in the range of about 20 to about 70 weight percent
of the composition.
[0016] Optionally, one or more electrically conductive filler
materials are utilized in the composition in addition to the
silver-plated fillers particles. Exemplary conductive filler
materials include, but are not limited to, silver, copper, gold,
palladium, platinum, nickel, gold or silver-coated nickel, carbon
black, carbon fiber, graphite, aluminum, indium tin oxide, silver
coated copper, silver coated aluminum, metallic coated glass
spheres, metallic coated filler, metallic coated polymers, silver
coated fiber, silver coated spheres, antimony doped tin oxide,
conductive nanospheres, nano silver, nano aluminum, nano copper,
nano nickel, carbon nanotubes and mixtures thereof. The
electrically conductive filler material may be the same as or
different than the core of any silver-plated filler particle
utilized in the composition. The one or more electrically
conductive filler materials comprise in the range of about 0 to
about 99 weight percent of the composition and preferably in the
range of up to about 40 weight percent of the composition.
[0017] The viscosity of the composition can be adjusted with
solvents. It is generally preferred that the composition have a low
viscosity to enable efficient dispensing, stencil or screen
printing of the composition. In one embodiment the composition has
a viscosity in the range of about 50 to about 150,000 mPas, and in
another embodiment is in the range of about 500 to about 50,000
mPas. The lower range of viscosity, from about 500 to about 4,000
mPas, is preferred for rotogravure or flexo printing of the
composition. Higher range of viscosity, from about 3,000 to 50,000
mPas, is preferred for dispensing, stencil or screen printing the
composition.
[0018] Exemplary solvents that may be utilized, either separately
or in combination, are glycidyl ethers, for example 1,4-butanediol
diglycidyl ether; p-tert-butyl-phenyl glycidyl ether, allyl
glycidyl ether, glycerol diglycidyl ether, butyldiglycol,
2-(2-butoxyethoxy)-ethylester, butylglycolacetate, acetic acid,
2-butoxyethylester, butylglycol, 2-butoxyethanol, isophorone, 3,3,5
trimethyl-2-cyclohexene-1-one, dimethylsuccinate,
dimethylglutarate, dimethyladipate, water, acetic acid, dipropylene
glycol (mono)methyl ether, propylacetate, glycidyl ether of alkyl
phenol (commercially available from Cardolite Corporation as
Cardolite NC513), although other solvents may be utilized.
[0019] Additional ingredients, such as organic additives, may be
included in the formulation to provide desired properties. Various
additives that may be included are surface active agents,
surfactants, wetting agents, antioxidants, thixotropes,
reinforcement materials, silane functional perfluoroether,
phosphate functional perfluoroether, Canes, titanates, wax, phenol
formaldehyde, air release agents, flow additives, adhesion
promoters, rheology modifiers, surfactants, spacer beads and
mixtures thereof. The ingredients are specifically chosen to obtain
the desired balance of properties for the use of the resins
utilized in the particular composition. The additional ingredient
comprises up to about 20 weight percent of the composition and
preferably up to about 10 weight percent of the composition.
[0020] The composition is combined and then applied by dispensing,
stencil, screen, rotogravure or flexo printing onto a substrate to
form conductive tracts or electronic circuitry, followed by curing
and/or drying to produce conductivity. Typically, the composition
is cured and/or dried at 120.degree. C. for about 10 minutes. The
composition may be cured and/or dried at higher temperatures for
less time. In general, these compositions provide sheet resistivity
of less than 0.100 Ohm/square/25 .mu.m.
EXAMPLES
[0021] The invention is further illustrated by the following
non-limiting example.
[0022] A comparative Sample 1 and Samples A-G were prepared by
dissolving the binder in a heated solvent (40.degree. C.) with
stirring until a homogenous mixture was formed, The samples were
cooled to room temperature, filler was added, and the mixture
stirred for an additional 30 minutes. As needed, a 3-roll mill
(Buhler) was used to mil the compositions. Each composition was
applied as a track of 100.times.2 mm with a thickness of about 5-8
.mu.m on a polyester sheet. The composition was cured and/or dried
at 120.degree. C. for 10 minutes, after which the sheet resistance
was measured using a Keithley 2000 Multimeter. Sheet resistivity
(SR) was calculated by the formula:
SR = R ( tr ) .times. W ( tr ) .times. H ( tr ) L ( tr ) .times. 25
, ##EQU00001##
where
[0023] R(tr)=Resistance track (in Ohm)
[0024] W(tr)=Width of the track (in mm)
[0025] H(tr)=Thickness of the track (in gm)
[0026] L(tr)=Length of the track (in mm)
[0027] The formulations of the compositions and the sheet
resistivity for each are reported in Table 1: Compositions and
Sheet Resistivity.
TABLE-US-00001 TABLE 1 1 (g) A (g) B (g) C (g) D (g) E (g) F (g) G
(g) Formulation Components Binder - ESTANE 5703P.sup.1 5.2 5.2 5.2
5.2 5.4 Binder - UCAR VAGH.sup.2 4.0 4.0 4.0 4.0 4.2 6.5 Binder -
PKHC.sup.3 9.1 Binder - Bakelite Hartz 16.0 9132KP.sup.4 Solvent -
Dibasicesters.sup.5 40.8 40.8 40.8 40.8 34.3 Solvent -
Butylglycolacetate.sup.6 27.3 Solvent - Propylacetate.sup.7 28.5
Solvent - Arcosolv DPM.sup.8 12.6 Filler - Silver flake.sup.9 50.0
30.0 35.0 25.0 Filler - Silver plated copper 20.0 15.0 25.0
ZS-710.sup.10 Filler - Silver plated copper 52.3 63.6 65.0 65.5 NZS
610.sup.11 Organic Additive - BYK 354.sup.12 0.65 Organic Additive
- Glycerol.sup.13 5.81 Sheet Resistivity 0.010 0.032 0.024 0.040
0.050 0.032 0.019 0.084 (Ohm/square/25 .mu.m) .sup.1Polyester-type
thermoplastic polyurethane available from Noveon, Ohio, USA
.sup.2Vinylchloride vinylalcohol vinylacetate copolymer available
from Dow Chemical, Belgium .sup.3Phenoxy resin available from
Inchem, South Carolina, USA .sup.4Phenolicresin available from
Bakelite, Germany .sup.5Mixture of dimethylsuccinate,
dimethyladipate and dimethyglutarate available from Keyser &
McKay, Netherlands .sup.62(2-butoxy-ethoxy) ethanol available from
Chemproha, Netherland .sup.7n-propylacetate available from
Chemproha, Netherland .sup.8Dipropylene Glycol (Mono)Methyl Ether
available from Arco, Missouri, USA .sup.9Silver flake available
from Ferro, Ohio, USA .sup.10Silver plated copper available from
Ames Goldsmith, New York, USA .sup.11Silver plated copper available
from Ames Goldsmith, New York, USA .sup.12Polyacrylate in solution
available from BYK, Germany .sup.131,2,3 propanetriol available
from Chemproha, Netherland
[0028] Comparative Sample 1 with silver flake filler had a sheet
resistivity of 0.010 Ohms/square/25 .mu.m. Samples made with
mixtures of silver flakes and silver plated coppers (Samples A-C)
had comparable sheet resistivity to the Comparative Sample 1 and
acceptable sheet resistivity, lower than 0.100 Ohm/square/25
micron. Samples made with only silver plated copper, without any
silver flakes (Samples D-G), also resulted in comparable sheet
resistivity values to Comparative Sample 1, and acceptable sheet
resistivity, lower than 0.100 Ohm/square/25 micron. Samples D-G
demonstrated that various binder systems may be used to result in
comparable sheet resistivity values as Comparative Sample 1, and
acceptable sheet resistivity, lower than 0.100 Ohm/square/25
micron.
[0029] Many modifications and variations of this invention can be
made without departing from its spirit and scope, as will be
apparent to those skilled in the art. The specific embodiments
described herein are offered by way of example only, and the
invention is to be limited only by the terms of the appended
claims, along with the full scope of equivalents to which such
claims are entitled.
* * * * *