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 surface modified flexible substrate, comprising:
(a) direct printing a precursor composition onto the surface modified flexible substrate, the precursor composition comprising metallic particles; and
(b) heating the precursor composition to form the conductive feature on the surface modified 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 process further comprises:
(c) surface modifying selected regions of a surface of an initial substrate to form the surface modified flexible substrate.
6 . The process of claim 5 , wherein the surface modifying comprises surface energy patterning by increasing or decreasing the surface energy of the surface in the selected regions corresponding to where it is desired to confine the precursor composition.
7 . The process of claim 6 , wherein the surface modifying is performed with a laser.
8 . The process of claim 7 , wherein the laser removes hydroxyl groups from the surface.
9 . The process of claim 7 , wherein the laser forms pores on the substrate.
10 . The process of claim 7 , wherein the laser increases or decreases the hydrophilicity of the surface.
11 . The process of claim 5 , wherein the surface modifying comprises surface energy patterning by increasing or decreasing surface energy of the surface in selected regions corresponding to where it is desired to eliminate the precursor composition.
12 . The process of claim 11 , wherein the surface modifying is performed with a laser.
13 . The process of claim 12 , wherein the laser removes hydroxyl groups from the surface.
14 . The process of claim 12 , wherein the laser forms pores on the substrate.
15 . The process of claim 12 , wherein the laser increases or decreases the hydrophilicity of the surface.
16 . The process of claim 5 , wherein the surface modifying increases adhesion of the precursor composition to the substrate.
17 . The process of claim 5 , wherein the surface modifying is performed with a thermal print head.
18 . The process of claim 5 , wherein the surface modifying comprises chemically modifying the surface.
19 . The process of claim 5 , wherein the surface modifying comprises electrostatic printing.
20 . The process of claim 5 , wherein the surface modifying comprises micro-contact printing.
21 . The process of claim 5 , wherein the precursor composition has a surface tension of 20 to 50 dynes/cm.
22 . The process of claim 5 , wherein the direct printing comprises directing droplets of the precursor composition toward a surface of the substrate, the droplets having an average droplet size not greater than about 10 μm.
23 . The process of claim 22 , wherein the average droplet size is not greater than about 5 m.
24 . The process of claim 5 , wherein the direct printing comprises depositing droplets onto the substrate at a rate of 1000 drops per second or higher.
25 . The process of claim 24 , wherein each droplet comprise from about 25 to 100 picoliters of the precursor composition.
26 . The process of claim 5 , wherein the minimum feature size is not greater than 75 μm.
27 . The process of claim 5 , wherein the minimum feature size is not greater than 50 μm.
28 . The process of claim 5 , wherein the minimum feature size is not greater than 25 m.
29 . The process of claim 5 , wherein the conductive feature has a thickness greater than 1 μm.
30 . The process of claim 5 , wherein the conductive feature has a thickness greater than 5 m.
31 . The process of claim 5 , wherein the heating sinters adjacent metallic particles to one another.
32 . The process of claim 5 , wherein the metallic particles comprise a metal selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
33 . The process of claim 5 , wherein the metallic particles have a volume median particle size of not greater than 100 nanometers.
34 . The process of claim 5 , wherein the metallic particles comprise a metal and have a volume median particle size of not greater than 0.3 μm.
35 . The process of claim 34 , wherein the metallic particles comprise a cap or coating thereon.
36 . The process of claim 35 , wherein the cap or coating comprises an organic cap or coating.
37 . The process of claim 35 , wherein the cap or coating comprises a polymer.
38 . The process of claim 35 , 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.
39 . The process of claim 35 , wherein the cap or coating comprises PVP;
40 . The process of claim 34 , wherein at least 80 volume percent of the metallic nanoparticles are not larger than twice the average particle size.
41 . The process of claim 34 , wherein the conductivity of the conductive feature is no less than 10 percent the conductivity of the equivalent pure metal.
42 . The process of claim 34 , wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
43 . The process of claim 34 , wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
44 . The process of claim 5 , wherein the heating comprises heating the precursor composition to a temperature not greater than 300° C. to form the conductive feature on the substrate.
45 . The process of claim 5 , wherein the heating comprises heating the precursor composition to a temperature not greater than 225° C. to form the conductive feature on the substrate.
46 . The process of claim 5 , wherein the heating comprises heating the precursor composition to a temperature not greater than 1 85° C. to form the conductive feature on the substrate.
47 . The process of claim 5 , wherein the substrate has a softening point of not greater than about 225° C.
48 . The process of claim 5 , wherein the flexible substrate has a softening point of not greater than about 185° C.
49 . The process of claim 5 , wherein the flexible substrate has a softening point of not greater than about 150° C.
50 . The process of claim 5 , wherein the flexible substrate comprises a polyimide.
51 . The process of claim 5 , wherein the flexible substrate comprises a polymer.
52 . The process of claim 5 , 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.
53 . The process of claim 5 , wherein the conductive feature comprises an electrode in a solar cell.
54 . The process of claim 5 , wherein the conductive feature is employed in a flat panel display.
55 . The process of claim 5 , wherein the conductive feature comprises a transparent conductive feature.
56 . The process of claim 5 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.
57 . A process for forming a conductive feature on a surface modified flexible substrate, the process comprising heating an ink jet printed precursor composition to form the conductive feature on the surface modified flexible substrate, wherein the precursor composition comprises metallic particles, and wherein the conductive feature has a width of not greater than 100 μm.
58 . The process of claim 57 , wherein the precursor composition has a surface tension of 20 to 50 dynes/cm.
59 . The process of claim 57 , wherein the width is not greater than 75 μm.
60 . The process of claim 57 , wherein the width is not greater than 50 μm.
61 . The process of claim 57 , wherein the width is not greater than 25 μm.
62 . The process of claim 57 , wherein the conductive feature has a thickness greater than 1 m.
63 . The process of claim 57 , wherein the conductive feature has a thickness greater than 5 m.
64 . The process of claim 57 , wherein the heating sinters adjacent metallic particles to one another.
65 . The process of claim 57 , wherein the metallic particles comprise a metal selected from the group consisting of silver, palladium, copper, gold, platinum and nickel.
66 . The process of claim 57 , wherein the metallic particles have a volume median particle size of not greater than 100 nanometers.
67 . The process of claim 57 , wherein the metallic particles comprise a metal and have a volume median particle size of not greater than 0.3 μm.
68 . The process of claim 67 , wherein the metallic particles comprise a cap or coating thereon.
69 . The process of claim 68 , wherein the cap or coating comprises an organic cap or coating.
70 . The process of claim 68 , wherein the cap or coating comprises a polymer.
71 . The process of claim 68 , 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.
72 . The process of claim 68 , wherein the cap or coating comprises PVP.
73 . The process of claim 67 , wherein at least 80 volume percent of the metallic nanoparticles are not larger than twice the average particle size.
74 . The process of claim 67 , wherein the conductivity of the conductive feature is no less than 10 percent the conductivity of the equivalent pure metal.
75 . The process of claim 34 , wherein the conductive feature has a resistivity that is not greater than 4 times the resistivity of the equivalent pure metal.
76 . The process of claim 67 , wherein the conductive feature has a resistivity that is not greater than 2 times the resistivity of the equivalent pure metal.
77 . The process of claim 57 , wherein the heating comprises heating the precursor composition to a temperature not greater than 300° C. to form the conductive feature on the substrate.
78 . The process of claim 57 , wherein the heating comprises heating the precursor composition to a temperature not greater than 225° C. to form the conductive feature on the substrate.
79 . The process of claim 57 , wherein the heating comprises heating the precursor composition to a temperature not greater than 185° C. to form the conductive feature on the substrate.
80 . The process of claim 57 , wherein the substrate has a softening point of not greater than about 225° C.
81 . The process of claim 57 , wherein the flexible substrate has a softening point of not greater than about 185° C.
82 . The process of claim 57 , wherein the flexible substrate has a softening point of not greater than about 150° C.
83 . The process of claim 57 , wherein the flexible substrate comprises a polyimide.
84 . The process of claim 57 , wherein the flexible substrate comprises a polymer.
85 . The process of claim 57 , 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.
86 . The process of claim 57 , wherein the conductive feature comprises an electrode in a solar cell.
87 . The process of claim 57 , wherein the conductive feature is employed in a flat panel display.
88 . The process of claim 57 , wherein the conductive feature comprises a transparent conductive feature.
89 . The process of claim 57 , wherein the conductive feature comprises indium-tin oxide or antimony-tin oxide.