U.S. patent application number 16/823383 was filed with the patent office on 2020-12-24 for catalyst ink for three-dimensional conductive constructs.
The applicant listed for this patent is Science Applications International Corporation. Invention is credited to David Morris, Jason Schipp, John Timler.
Application Number | 20200399482 16/823383 |
Document ID | / |
Family ID | 1000004838324 |
Filed Date | 2020-12-24 |
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United States Patent
Application |
20200399482 |
Kind Code |
A1 |
Morris; David ; et
al. |
December 24, 2020 |
Catalyst Ink for Three-Dimensional Conductive Constructs
Abstract
A method of constructing conductive material in arbitrary
three-dimensional (3D) geometries, such as 3D printing. The method
may include selective application of an aerosol-based colloidal
solution containing a catalytic palladium nanoparticle material
onto a substrate and then immersion of the coated substrate into an
electro-less plating bath for deposition of conductive copper
material. The above steps may be repeated to create arbitrary 3D
geometric constructs containing conductive metallic patterns.
Inventors: |
Morris; David; (Bloomington,
IN) ; Timler; John; (River Ridge, LA) ;
Schipp; Jason; (Jasper, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Science Applications International Corporation |
Reston |
VA |
US |
|
|
Family ID: |
1000004838324 |
Appl. No.: |
16/823383 |
Filed: |
March 19, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16447277 |
Jun 20, 2019 |
10619059 |
|
|
16823383 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B33Y 70/00 20141201;
B82Y 30/00 20130101; C23C 18/38 20130101; C23C 18/161 20130101;
C09D 11/03 20130101; B33Y 10/00 20141201; C23C 18/1637 20130101;
B33Y 40/00 20141201; C23C 18/1662 20130101 |
International
Class: |
C09D 11/03 20060101
C09D011/03; C23C 18/16 20060101 C23C018/16; C23C 18/38 20060101
C23C018/38 |
Goverment Interests
GOVERNMENT LICENSE RIGHTS
[0002] This invention was made with Government support under
Contract No. N00178-04-D-4119-FC2846 awarded by the U.S. Department
of Defense. The Government has certain rights in this invention.
Claims
1. An arbitrary three-dimensional construct prepared by i.
preparing a catalyst ink comprising a colloidal solution comprising
a solvent and palladium nanoparticles; and ii. depositing the
catalyst ink from step (i) onto a surface of a substrate using
aerosol jet printing; iii. subjecting the substrate to electro-less
plating to plate the palladium nanoparticles with copper; and iv.
repeating steps ii and iii until the three-dimensional construct is
formed.
2. The construct of claim 1 further comprising sonicating the
solvent in step i to disperse the palladium nanoparticles and to
reduce aggregation of the palladium nanoparticles.
3. The construct of claim 1 wherein the solvent is selected from
toluene, dimethylformamide, tetrahydrofuran, xylenes, and
combinations thereof.
4. The construct of claim 1 wherein the catalyst ink further
comprises a binder selected from poly-vinyl alcohol and
carboxy-methyl cellulose or combinations thereof.
5. The construct of claim 1 wherein the palladium nanoparticles
have an average particle size of from about 15 to about 400 nm.
6. The construct of claim 1 wherein the palladium nanoparticles are
present in the catalyst ink in an amount of from 0.1 to 2.2 wt.
%.
7. The construct of claim 1 wherein the substrate is selected from
glass, plastic, ceramic, or metal.
8. The construct of claim 1 further comprising v. applying a
non-conductive layer prior to or after repeating steps ii and
iii.
9. The construct of claim 1 wherein the catalyst ink further
comprises a binder selected from poly-vinyl alcohol and
carboxy-methyl cellulose or combinations thereof.
10. The construct of claim 8 wherein the palladium nanoparticles
have an average particle size of from about 15 to about 400 nm.
11. The construct of claim 8 which construct is microelectronic
circuitry.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 16/447,277, filed Jun. 20, 2019, now allowed,
the disclosure of which is herein incorporated by reference in its
entirety.
BACKGROUND
[0003] To date there has not been an effective deposition process
for metallic compounds that provides conductivity on par with bulk
metal in arbitrary three-dimensional geometries. In particular,
current ink or aerosol based precursors used in such additive
manufacturing processes do not provide the desired conductivity in
the product material. Three-dimensional metal shapes printed with
current inks only achieve 30% of the conductivity of their bulk
material counterparts.
SUMMARY
[0004] The following presents a simplified summary in order to
provide a basic understanding of the disclosure. The summary is not
an extensive overview of the disclosure. It is neither intended to
identify key or critical elements nor to delineate the scope of the
disclosure. The following summary merely presents some concepts in
a simplified form as a prelude to the more detailed description
below.
[0005] A catalyst ink may comprise a colloidal solution of a
solvent and palladium nanoparticles. The colloidal solution may
comprise a binder. The catalyst ink may be used to form a
three-dimensional construct. A method of forming a
three-dimensional construct may comprise preparing a catalyst ink
by forming a colloidal solution comprising catalytic nanoparticles
and a solvent. The catalytic ink may be deposited onto a surface of
a substrate. The ink may be deposited, for example, using aerosol
jet printing. The substrate may be subjected to electro-less
plating to plate the deposited nanoparticles with metal. One or
more of these steps may be repeated until a three-dimensional
construct having a desired size and/or shape is formed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 shows an example aerosol jet system used to apply
nanoparticles in accordance with one aspect of the disclosure.
[0007] FIG. 2 shows a flow chart of a method of preparing a 3-D
construct in accordance with one aspect of the disclosure.
[0008] FIG. 3 shows an example of palladium traces before addition
of copper with 1% palladium in accordance with one aspect of the
disclosure.
[0009] FIG. 4 shows an example of palladium traces before addition
of copper with 0.5% palladium in accordance with one aspect of the
disclosure.
[0010] FIG. 5 shows an example of a copper construct in accordance
with one aspect of the disclosure.
[0011] FIG. 6 shows an example of a copper construct in accordance
with another aspect of the disclosure.
DESCRIPTION
[0012] The present disclosure is directed to the preparation of
arbitrary three-dimensional (3D) geometric conductive constructs.
The term "arbitrary" is intended to convey that the constructs may
be of a variety of shapes and sizes. The constructs may be used to
form microelectronic circuitry, which can be used for flexible
sensors, transistors, connective wiring, etc.
[0013] A process for preparing arbitrary 3D shapes may include
additive or subtractive manufacturing techniques. In addition, the
layers in the construct may be partly conductive and partly
non-conductive. For example, a non-reactive ink may be utilized to
build one or more portions of the 3D construct to form a
non-conductive layer and then a catalyst ink may be used to build
one or more portions of the 3D construct. Thus the process provides
conductive metallic patterns.
[0014] The process of making the 3D conductive constructs may use a
colloidal solution containing a catalytic nanoparticle material,
for example palladium. The colloidal solution may be an
aerosol-based solution and may be referred to as a catalyst ink.
The catalyst ink may be applied onto a substrate using aerosol jet
printing. "Aerosol jet printing" and an "aerosol jet printing
process" refer to printing processes whereby liquid is projected
from a nozzle directly onto a substrate to form a desired
pattern.
[0015] The catalytic nanoparticle material may be disposed in
minute amounts on the surface. The catalytic nanoparticle material,
and/or a layer of such materials, may itself be nonconductive. The
catalytic nanoparticle material may facilitate subsequent
deposition of a metal onto the surface, according to the pattern of
the catalytic nanoparticle material previously deposited, so as to
form conductive layers in the 3D construct.
[0016] For example, the catalytic nanoparticle material coated
substrate may be immersed into an electro-less plating bath for
deposition of conductive material such as copper onto the
nanoparticles. The above steps may be repeated to create the
desired 3D conductive constructs.
[0017] Attention is drawn to FIG. 2 which shows a flow diagram that
may be used to apply conductive layers to form a 3D construct. In
step 202, nanoparticles and solvent may be combined and subjected
to sonication to form a colloidal solution. In step 204, the
colloidal solution may be added to an aerosol jet printer. In step
206, the solution may be applied to a substrate to form a layer of
nanoparticles. In step 208, the coated substrate may be plated with
a conductive metal. In step 210, a determination may be made with
regard to whether the 3D construct is complete. If not complete,
steps 206-210 may be repeated until the 3D construct is
complete.
[0018] The catalyst ink (colloidal or aerosol-based solution) may
contain catalytic nanoparticles, solvents, and optionally a
binder.
[0019] The nanoparticles may be any suitable palladium
nanoparticles that one can use to build a 3D geometric conductive
construct. Active palladium is catalytic for subsequent addition of
a metal onto the palladium and strongly attaches to the underlying
substrate. Palladium may be used, in particular, for copper
plating. Hence, after application of the palladium particles, for
example, the construct may be immersed in an electro-less plating
bath for application of the copper.
[0020] The catalytic nanoparticles may be of any suitable size for
deposition and buildup of the 3D construct. For example, the
average particle size may be from 15 to 400 nm in size. The average
particle sizes may be a consistent size or may be random within the
range or may have groups of larger and smaller particles within the
range, for example 15 to 200 nm, 15 to 100 nm, 15 to 50 nm, 100 to
400 nm, 200 to 400 nm, 300 to 400 nm, 100 to 300 nm or 15 to 250 nm
or any combination thereof.
[0021] The colloidal solution may contain a suitable concentration
of catalytic nanoparticles to provide the desired layer of
particles. The concentration of catalytic nanoparticles in the
solution may be limited so as to avoid clogging the nozzle of the
applicator. The colloidal solution may contain from 0.1 to 2.2 wt.
% nanoparticles, for example, from 0.1 to 1.5 wt. %, 0.1 to 1.0 wt
%, 0.1 to 0.5 wt. %, 0.5 to 2.2 wt. %, 1 to 2.2 wt %, 1.5 to 2.2
wt. %, or 0.5 to 1.5 wt. %. The concentration may be any suitable
concentration to obtain the desired layer thickness on the
substrate.
[0022] The solvent may be any suitable solvent to provide a
colloidal solution of the catalytic nanoparticles and suitable for
spraying to build the 3D construct. Suitable solvents include, but
are not limited to, toluene, dimethylformamide, tetrahydrofuran,
xylenes, and combinations thereof.
[0023] A binder may be utilized to increase the substrate/catalyst
interaction. With certain substrates, no binder is utilized. The
selection of a binder and type of binder may depend, at least in
part, on the characteristics of the substrate, the solvent, and the
catalytic nanoparticles. Suitable binders for palladium
nanoparticles include, but are not limited to, poly-vinyl alcohol
and carboxy-methyl cellulose or combinations thereof. The type and
amount of binder is dependent on the substrate but generally does
not exceed more than 1% of total solution.
[0024] Other processing aids may be included so long as they do not
interfere with the desired 3-D construct.
[0025] The colloidal solution components may be mixed together. The
resulting solution may be sonicated to reduce aggregation of the
nanoparticles and disperse the nanoparticles in solution. Such
sonication may occur just prior to dispersion to ensure the
nanoparticles have not aggregated and/or settled. The colloidal
solution may be sonicated for up to 20 minutes, typically 10 to 15
minutes. The resulting solution may have a viscosity of less than
1000 cP measured at room temperature to allow suitable flow.
[0026] In an aerosol jet printer 100, illustrated in FIG. 1, an
atomizer 102 atomizes a liquid 104 (e.g., an ink such as a
colloidal solution). The atomized fluid 106 enters a virtual
impactor 110 to remove excess gas, and then is aerodynamically
focused using a flow guidance deposition head 114, which creates an
annular flow of sheath gas, indicated by arrow 116, to collimate
the atomized fluid 118. The co-axial flow exits the flow guidance
head 114 through a nozzle 120 directed at the substrate 130 and
focuses a stream 122 of the atomized material. Patterning may be
accomplished by attaching the substrate to a computer-controlled
platen, or by translating the flow guidance head while the
substrate position remains fixed. An example of an aerosol jet
printer suitable for use includes, but is not limited to, an M3D
Aerosol Jet Deposition System available from Optomec, Inc., of
Albuquerque, N.M.
[0027] The system may use a single nozzle or a plurality of nozzles
(e.g. 1, 2, 3, 4, 5, or more nozzles.) The nozzles may be attached
to a multiplex or other system to allow non-conformal
printing--e.g. control of the nozzle(s) in a 3-dimensional
environment.
[0028] The colloidal solution may be loaded into a pneumatic
atomizer chamber of the aerosol jet printer. A liquid stream of the
colloidal solution may be atomized using a high-velocity
atomization gas stream. This high-velocity gas shears the liquid
stream into droplets thus forming an aerosol stream. The droplets
may be of any suitable size for application to the substrate or
construct. Typically the droplets range from 1 to 5 .mu.m, for
example, with an average size of 2.5 .mu.m. Suitable atomization
gases may be inert gases such as nitrogen or argon or compressed
air. Nitrogen may be preferred over argon as it is less
expensive.
[0029] Excess atomization gas may be removed from the aerosol
stream by a virtual impactor which then concentrates the aerosol
stream and channels the aerosol stream through a deposition head. A
sheath gas stream surrounds the aerosol stream and focuses the
stream onto the substrate forming a layer of nanoparticles on the
substrate or on the construct already present.
[0030] The process of applying the nanoparticles may occur at a
temperature of from 0 to 60 degrees Celsius to the print bed.
[0031] The print thickness of each layer may be 100 nanometers to
tens of microns. A typical range is from 0.5 to 1.5 microns.
[0032] The substrates may be standard 2D substrates or additively
manufactured 3D constructs. More particularly, the substrates may
be flat sheets or they may be 3D structures that were made using
additive manufacturing from a 3D printer. Substrates may be made of
glass, plastics, ceramics, and metals. The substrate may be any
substrate that the colloidal solution gets printed on. A plate of
ceramic may be a substrate or a 3D printed plastic pyramid may be a
substrate. The substrate becomes part of the product.
[0033] After application of the metal precursor, the substrate may
be allowed to dry. FIG. 3 shows a substrate 300 coated utilizing 1%
palladium solution to form structure 302. FIG. 4 shows a substrate
400 coated utilizing 0.5% palladium solution to form structure 402.
These structures may be used in microelectronic circuitry.
[0034] The palladium coated substrate may be metallized by
immersing in an electro-less plating bath. For example, substrate
having a layer of palladium nanoparticles may be immersed in a
copper bath whereby the copper plates onto the palladium. The
solvent may be left to evaporate, for example, the substrate may
sit in room temperature for 2 hours, or placed in an oven, for
example, at 50 to 60 degrees Celsius for 30 minutes.
[0035] Subsequent process steps may include washing the copper
plating. Washing may be with water, an acid solution such as
sulfuric acid, and/or anti-tarnish. As a non-limiting
exemplification, the plated sample may be washed with deionized
(DI) water for two minutes, washed with 10% sulfuric acid for 1
minutes, 45 seconds, rinsed with DI water again for 1 minute, then
washed with anti-tarnish solution for 1 minute, and lastly washed
with DI water for one minute.
[0036] The process may be repeated to add additional conductive
metal layers to the substrate constructs. The process may also
include application of non-catalytic or non-metallic layers. FIG. 5
shows substrate 400 where the palladium has been coated in copper
to form a conductive, flexible wire 502 which may be used in
microelectronic circuitry FIG. 6 shows another substrate 600 coated
with palladium to form structure 602 which may be used in
microelectronic circuitry.
[0037] The resulting metal 3D structure (construct) may have a
conductivity on par with bulk metal counterparts that require
sintering (e.g. silver constructs).
[0038] As discussed above, an aerosol system may use a sheath of
gas to channel the colloidal solution through the print head. The
sheath gas allows the colloidal solution to channel through the
print head without touching the nozzle walls. This creates a clog
resistant nozzle and a tightly focused, high density stream onto
the substrate.
[0039] An advantage of the aerosol system is that it can produce a
much higher print resolution than that of standard ink jet systems.
The aerosol system is also more lenient than ink jet with ink
viscosity and print head standoff. The variable print head standoff
offered by the aerosol jet system allows nanoparticles to be
printed on variable surface features that would simply not be
possible with an ink jet printer. This allows for printing on
3-dimensional surfaces, which ink jet systems cannot do.
[0040] Additional aspects include a catalytic ink comprising
palladium, a solvent selected from toluene, dimethylformamide,
tetrahydrofuran, xylenes, and combinations thereof, and optionally
a binder selected from poly-vinyl alcohol and carboxy-methyl
cellulose.
Examples
[0041] A copper construct made in accordance with the process of
using a palladium ink and an aerosol system as described herein was
compared to a silver construct prepared with an industry standard
silver ink using the same aerosol system. The palladium construct
showed improvements over the silver constructs. Three passes with
the Optomec M3D Aerosol Jet Deposition System, Inc. using silver
ink provided resistances of 14.5 to 27 ohms, after sintering the
silver for 5 hours at 205 C.degree.. Three passes with the
palladium ink followed by copper plating provided a resistance of
3.26 to 5.75 ohms, with no sintering at high temperatures being
required.
[0042] The invention has been described with respect to specific
examples including various aspects of the invention. Those skilled
in the art will appreciate that there are numerous variations and
permutations of the above described systems and techniques. Thus,
the spirit and scope of the invention should be construed broadly
as set forth in the appended claims.
* * * * *