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 onto the flexible substrate, the precursor composition comprising metallic nanoparticles, the metallic nanoparticles comprising a metallic core and a cap or coating disposed thereon; and
(b) heating the precursor composition to a temperature not greater than 300° C. to form the conductive feature on the flexible substrate.
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 cap or coating comprises an elemental metal.
6 . The process of claim 4 , wherein the cap or coating comprises an organic compound.
7 . The process of claim 4 , wherein the cap or coating comprises a polymer.
8 . The process of claim 4 , 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.
9 . The process of claim 4 , wherein the cap or coating comprises PVP.
10 . The process of claim 4 , wherein the metallic core comprises a metal selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
11 . The process of claim 10 , wherein the cap or coating comprises PVP.
12 . The process of claim 4 , wherein core comprises a conductive metal oxide.
13 . The process of claim 4 , wherein the metallic nanoparticles have a volume median particle size of not greater than 100 nm.
14 . The process of claim 4 , wherein the cap or coating has a thickness of not greater than about 100 nm.
15 . The process of claim 4 , wherein the cap or coating has a thickness of not greater than about 50 nm.
16 . The process of claim 4 , wherein the cap or coating has a thickness of not greater than about 5 nm.
17 . The process of claim 4 , wherein the cap or coating enhances bonding of the nanoparticles to the substrate.
18 . The process of claim 4 , wherein the cap or coating prevents agglomeration of the metallic nanoparticles while in the precursor composition.
19 . The process of claim 4 , wherein the heating sinters adjacent nanoparticles to one another.
20 . 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.
21 . 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.
22 . The process of claim 4 , wherein the substrate has a softening point of not greater than about 225° C.
23 . The process of claim 4 , wherein the flexible substrate has a softening point of not greater than about 185° C.
24 . The process of claim 4 , wherein the flexible substrate has a softening point of not greater than about 150° C.
25 . The process of claim 4 , wherein. the flexible substrate comprises a polyimide.
26 . The process of claim 4 , wherein the flexible substrate comprises a polymer.
27 . 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.
28 . The process of claim 4 , wherein the conductive feature comprises an electrode in a solar cell.
29 . The process of claim 4 , wherein the conductive feature is employed in a flat panel display.
30 . The process of claim 4 , wherein the conductive feature has a width less than 100 μm.
31 . The process of claim 4 , wherein the conductive feature has a thickness greater than 5 μm.
32 . The process of claim 4 , wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
33 . The process of claim 4 , wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
34 . The process of claim 4 , wherein the conductive feature has a thickness greater than 1 μm.
35 . The process of claim 4 , wherein the conductive feature has a thickness greater than 5 μm.
36 . The process of claim 4 , wherein the conductive feature comprises a transparent a conductive feature.
37 . The process of claim 4 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
38 . The process of claim 4 , wherein the process further comprises surface modifying the substrate with a laser.
39 . The process of claim 38 , wherein the laser increases or decreases the hydrophilicity of the substrate.
40 . A process for forming a conductive feature on a flexible substrate, the process comprising heating an ink jet printed precursor composition to a temperature not greater than 300° C. to form the conductive feature on the flexible substrate, wherein the precursor composition comprises metallic nanoparticles having a core comprising a metal and a cap or coating disposed on the core.
41 . The process of claim 40 , wherein the cap or coating comprises an elemental metal.
42 . The process of claim 40 , wherein the cap or coating comprises an organic compound.
43 . The process of claim 40 , wherein the cap or coating comprises a polymer.
44 . The process of claim 40 , wherein the cap or coating comprises a conductive polymer.
45 . The process of claim 40 , 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.
46 . The process of claim 40 , wherein the cap or coating comprises PVP.
47 . The process of claim 40 , wherein the metal is selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
48 . The process of claim 47 , wherein the cap or coating comprises PVP.
49 . The process of claim 40 , wherein core comprises a conductive metal oxide.
50 . The process of claim 40 , wherein the metallic nanoparticles have a volume median particle size of not greater than 100 nm.
51 . The process of claim 40 , wherein the cap or coating has a thickness of not greater than about 100 nm.
52 . The process of claim 40 , wherein the cap or coating has a thickness of not greater than about 50 nm.
53 . The process of claim 40 , wherein the cap or coating has a thickness of not greater than about 5 nm.
54 . The process of claim 40 , wherein the cap or coating enhances bonding of the nanoparticles to the substrate.
55 . The process of claim 40 , wherein the cap or coating prevents agglomeration of the metallic nanoparticles while in the precursor composition.
56 . The process of claim 40 , wherein the heating sinters adjacent nanoparticles to one another.
57 . The process of claim 40 , wherein the heating comprises heating the precursor composition to a temperature not greater than 225° C. to form the conductive feature on the substrate.
58 . The process of claim 40 , wherein the heating comprises heating the precursor composition to a temperature not greater than 185° C. to form the conductive feature on the substrate.
59 . The process of claim 40 , wherein the substrate has a softening point of not greater than about 225° C.
60 . The process of claim 40 , wherein the flexible substrate has a softening point of not greater than about 185° C.
61 . The process of claim 40 , wherein the flexible substrate has a softening point of not greater than about 150° C.
62 . The process of claim 40 , wherein the flexible substrate comprises a polyimide.
63 . The process of claim 40 , wherein the flexible substrate comprises a polymer.
64 . The process of claim 40 , 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.
65 . The process of claim 40 , wherein the conductive feature comprises an electrode in a solar cell.
66 . The process of claim 40 , wherein the conductive feature is employed in a flat panel display.
67 . The process of claim 40 , wherein the conductive feature has a width less than 100 μm.
68 . The process of claim 40 , wherein the conductive feature has a thickness greater than 5 μm.
69 . The process of claim 40 , wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
70 . The process of claim 40 , wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
71 . The process of claim 40 , wherein the conductive feature has a thickness greater than 1 μm.
72 . The process of claim 40 , wherein the conductive feature has a thickness greater than 5 μm.
73 . The process of claim 40 , wherein the conductive feature comprises a transparent conductive feature.
74 . The process of claim 40 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.