Low viscosity precursor compositions and methods for the deposition of conductive electronic features
A precursor composition for the deposition and formation of an electrical feature such as a conductive feature. The precursor composition advantageously has a low viscosity enabling deposition using direct-write tools. The precursor composition also has a low conversion temperature, enabling the deposition and conversion to an electrical feature on low temperature substrates. A particularly preferred precursor composition includes silver metal for the formation of highly conductive silver features.
1 . A process for forming a conductive feature on a flexible substrate, comprising:
(a) direct printing a precursor composition comprising metallic nanoparticles onto the flexible substrate; and
(b) heating the precursor composition to form the conductive feature on the flexible substrate, the conductive feature having a minimum feature size of not greater than 100 μm.
2 . The process of claim 1 , wherein the direct printing comprises syringe printing.
3 . The process of claim 1 , wherein the direct printing comprises aerosol jet deposition.
4 . The process of claim 1 , wherein the direct printing comprises ink jet printing.
5 . The process of claim 4 , wherein the direct printing comprises directing droplets of the precursor composition toward a surface of the flexible substrate, the droplets having an average droplet size not greater than about 10 μm.
6 . The process of claim 5 , wherein the average droplet size is not greater than about 5 μm.
7 . The process of claim 4 , wherein the ink jet printing comprises depositing droplets onto the substrate at a rate of 1000 drops per second or higher.
8 . The process of claim 7 , wherein each droplet comprise from about 25 to 100 picoliters of the precursor composition.
9 . The process of claim 4 , wherein the minimum feature size is not greater than 75 μm.
10 . The process of claim 4 , wherein the minimum feature size is not greater than 50 μm.
11 . The process of claim 4 , wherein the minimum feature size is not greater than 25 μm.
12 . The process of claim 4 , wherein the process further comprises surface modifying a surface of the substrate prior to the direct printing.
13 . The process of claim 12 , wherein the surface modifying comprises laser patterning.
14 . The process of claim 13 , wherein the laser patterning increases or decreases the hydrophilicity of the substrate.
15 . The process of claim 12 , wherein the surface modifying comprises forming trenches in the surface by chemical etching or photochemical means.
16 . The process of claim 4 , wherein the metallic nanoparticles comprise a metal selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
17 . The process of claim 4 , wherein the metallic nanoparticles have a volume median particle size of not greater than 100 nm.
18 . The process of claim 17 , wherein the metallic nanoparticles comprise a cap or coating thereon.
19 . The process of claim 18 , wherein the cap or coating comprises an organic cap or coating.
20 . The process of claim 18 , wherein the cap or coating comprises a polymer.
21 . The process of claim 18 , wherein the cap or coating comprises an intrinsically conductive polymer, a sulfonated perfluorohydrocarbon polymer, polystyrene, polystyrene/methacrylate, sodium bis(2-ethylhexyl) sulfosuccinate, tetra-n-octyl-ammonium bromide or an alkane thiolate.
22 . The process of claim 18 , wherein the cap or coating comprises PVP.
23 . The process of claim 17 , wherein at least 80 volume percent of the metallic nanoparticles are not larger than twice the average particle size.
24 . The process of claim 4 , wherein the conductive feature has a thickness greater than 1 μm.
25 . The process of claim 4 , wherein the conductive feature has a thickness greater than 5 μm.
26 . The process of claim 4 , wherein the heating sinters adjacent metallic nanoparticles to one another.
27 . The process of claim 4 , wherein the heating comprises heating the precursor composition to a temperature not greater than 300° C. to form the conductive feature on the substrate.
28 . The process of claim 4 , wherein the heating comprises heating the precursor composition to a temperature not greater than 225° C. to form the conductive feature on the substrate.
29 . The process of claim 4 , wherein the heating comprises heating the precursor composition to a temperature not greater than 185° C. to form the conductive feature on the substrate.
30 . The process of claim 4 , wherein the substrate has a softening point of not greater than about 225° C.
31 . The process of claim 4 , wherein the flexible substrate has a softening point of not greater than about 185° C.
32 . The process of claim 4 , wherein the flexible substrate has a softening point of not greater than about 150° C.
33 . The process of claim 4 , wherein the flexible substrate comprises a polyimide.
34 . The process of claim 4 , wherein the flexible substrate comprises a polymer.
35 . The process of claim 4 , wherein the metallic nanoparticles comprise a metal, and wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
36 . The process of claim 4 , wherein the metallic nanoparticles comprise a metal, and wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
37 . The process of claim 4 , wherein the flexible substrate is selected from the group consisting of polyfluoronated compounds, polyimides, epoxies, polycarbonates, paper, acetate, polyester, polyethylene, polypropylene, polyvinyl chloride, acrylonitrile, butadiene, flexible fiber board, non-woven polymeric fabric, cloth, metallic foil and thin glass.
38 . The process of claim 4 , wherein the conductive feature comprises an electrode in a solar cell.
39 . The process of claim 4 , wherein the conductive feature is employed in a flat panel display.
40 . The process of claim 4 , wherein the conductive feature comprises a transparent conductive feature.
41 . The process of claim 4 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
42 . A process for forming a conductive feature on a flexible substrate, the process comprising heating an ink jet printed precursor composition to form the conductive feature on the flexible substrate, wherein the precursor composition comprises metallic nanoparticles, and wherein the conductive feature has a minimum feature size of not greater than 100 μm.
43 . The process of claim 42 , wherein the minimum feature size is not greater than 75 μm.
44 . The process of claim 42 , wherein the minimum feature size is not greater than 50 μm.
45 . The process of claim 42 , wherein the minimum feature size is not greater than 25 μm.
46 . The process of claim 42 , wherein the metallic nanoparticles comprise a metal selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
47 . The process of claim 42 , wherein the metallic nanoparticles have a volume median particle size of not greater than 100 nm.
48 . The process of claim 47 , wherein the metallic nanoparticles comprise a cap or coating thereon.
49 . The process of claim 48 , wherein the cap or coating comprises an organic cap or coating.
50 . The process of claim 48 , wherein the cap or coating comprises a polymer.
51 . The process of claim 48 , wherein the cap or coating comprises an intrinsically conductive polymer, a sulfonated perfluorohydrocarbon polymer, polystyrene, polystyrene/methacrylate, sodium bis(2-ethylhexyl) sulfosuccinate, tetra-n-octyl-ammonium bromide or an alkane thiolate.
52 . The process of claim 48 , wherein the cap or coating comprises PVP.
53 . The process of claim 47 , wherein at least 80 volume percent of the metallic nanoparticles are not larger than twice the average particle size.
54 . The process of claim 42 , wherein the conductive feature has a thickness greater than 1 μm.
55 . The process of claim 42 , wherein the conductive feature has a thickness greater than 5 μm.
56 . The process of claim 42 , wherein the heating sinters adjacent metallic nanoparticles to one another.
57 . The process of claim 42 , wherein the heating comprises heating the precursor composition to a temperature not greater than 300° C. to form the conductive feature on the substrate.
58 . The process of claim 42 , wherein the heating comprises heating the precursor composition to a temperature not greater than 225° C. to form the conductive feature on the substrate.
59 . The process of claim 42 , wherein the heating comprises heating the precursor composition to a temperature not greater than 185° C. to form the conductive feature on the substrate.
60 . The process of claim 42 , wherein the substrate has a softening point of not greater than about 225° C.
61 . The process of claim 42 , wherein the flexible substrate has a softening point of not greater than about 185° C.
62 . The process of claim 42 , wherein the flexible substrate has a softening point of not greater than about 150° C.
63 . The process of claim 42 , wherein the flexible substrate comprises a polyimide.
64 . The process of claim 42 , wherein the flexible substrate comprises a polymer.
65 . The process of claim 42 , wherein the metallic nanoparticles comprise a metal, and wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
66 . The process of claim 42 , wherein the metallic nanoparticles comprise a metal, and wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
67 . The process of claim 42 , wherein the flexible substrate is selected from the group consisting of polyfluoronated compounds, polyimides, epoxies, polycarbonates, paper, acetate, polyester, polyethylene, polypropylene, polyvinyl chloride, acrylonitrile, butadiene, flexible fiber board, non-woven polymeric fabric, cloth, metallic foil and thin glass.
68 . The process of claim 42 , wherein the conductive feature comprises an electrode in a solar cell.
69 . The process of claim 42 , wherein the conductive feature is employed in a flat panel display.
70 . The process of claim 42 , wherein the conductive feature comprises a transparent conductive feature.
71 . The process of claim 42 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.