Photonic sintering of polymer thick film conductor compositions

Abstract

This invention provides a method for using a polymer thick film conductor composition to form an electrical conductor in an electrical circuit, the method subjecting the deposited thick film conductor composition to photonic sintering. The invention also provides a method for reducing the resistance of an electrical conductor formed from a polymer thick film conductor composition, the method comprising the step of subjecting the electrical conductor to photonic sintering. The invention further provides devices containing electrical conductors made by these methods.

What is claimed is: 
     
         1 . An electrical device comprising an electrical conductor formed from a polymer thick film conductor composition, wherein said electrical conductor has been subjected to photonic sintering, wherein said polymer thick film conductor composition is a polymer thick film solder alloy conductor composition comprising:
 a) 65 to 95 wt % SAC solder alloy powder consisting of tin, silver, and copper, wherein said tin is greater than 90 wt % of said SAC solder alloy powder, said SAC solder alloy powder consisting of particles possessing an average particle size of 2 to 18 μm and a surface area/mass ratio in the range of 0.2 to 1.3 m 2 /g; dispersed in   (b) 5 to 35 wt % organic medium comprising:
 1) a vinyl co-polymer resin of vinylidene chloride and acrylonitrile, dissolved in 
 2) organic solvent comprising a dibasic ester; 
   wherein the wt % of said SAC solder alloy powder and said organic medium are based on the total weight of the polymer thick film solder alloy conductor composition.   
     
     
         2 . An electrical device comprising an electrical conductor formed from a polymer thick film conductor composition, wherein said electrical conductor has been subjected to photonic sintering, wherein said polymer thick film conductor composition is a polymer thick film solder alloy conductor composition comprising:
 (a) 35 to 94 wt % solder alloy powder selected from the group consisting of (i) SAC solder alloy powder consisting of tin, silver, and copper alloy powder, wherein said tin is greater than 90 wt % of said SAC solder alloy powder, (ii) solder alloy powder consisting of tin and bismuth alloy powder, wherein said tin is at least 40 wt % of said tin and bismuth alloy powder, and (iii) mixtures thereof, said alloy powder consisting of particles possessing an average particle size of 2 to 18 μm and a surface area/mass ratio in the range of 0.2 to 1.3 m 2 /g;   (b) 1 to 30 wt % metal selected from the group consisting of silver, copper, gold, aluminum and mixtures thereof, said metal consisting of particles possessing an average particle size of 2 to 18 μm and a surface area/mass ratio in the range of 0.1 to 2.3 m 2 /g; and   (c) 5 to 35 wt % organic medium comprising:
 (1) a resin that is a vinyl co-polymer resin of vinylidene chloride and acrylonitrile or a phenoxy resin; dissolved in 
 (2) organic solvent comprising a dibasic ester or glycol ether; 
   wherein if said resin is a phenoxy resin said metal is silver, wherein said solder alloy powder and said metal are dispersed in said organic medium and wherein the wt % of said solder alloy powder, said metal and said organic medium are based on the total weight of the polymer thick film conductor composition.   
     
     
         3 . An electrical device comprising an electrical conductor formed by a method comprising the use of a polymer thick film composition, wherein said polymer thick film composition is subjected to photonic sintering to form the electrical conductor. 
     
     
         4 . The electrical device of  claim 3 , said method comprising:
 A) providing a substrate;   B) providing a polymer thick film conductor composition, wherein said polymer thick film conductor composition is a polymer thick film solder alloy conductor composition comprising:
 (a) 65 to 95 wt % SAC solder alloy powder consisting of tin, silver, and copper, wherein said tin is greater than 90 wt % of said SAC solder alloy powder, said SAC solder alloy powder consisting of particles possessing an average particle size of 2 to 18 μm and a surface area/mass ratio in the range of 0.2 to 1.3 m 2 /g; dispersed in 
 (b) 5 to 35 wt % organic medium comprising
 (1) a vinyl co-polymer resin of vinylidene chloride and acrylonitrile, dissolved in 
 (2) organic solvent comprising a dibasic ester; wherein the wt % of said SAC solder alloy powder and said organic medium are based on the total weight of the polymer thick film solder alloy conductor composition; 
 
   C) applying said polymer thick film conductor composition onto said substrate; and   D) subjecting said polymer thick film conductor composition to photonic sintering to form said electrical conductor.   
     
     
         5 . The electrical device of  claim 4 , said method further comprising a step of drying said polymer thick film conductor composition, wherein said step of drying is carried out following step (C) but before step (D). 
     
     
         6 . The electrical device of  claim 3 , said method comprising:
 A) providing a substrate;   B) providing a polymer thick film conductor composition, wherein said polymer thick film conductor composition is a polymer thick film solder alloy/metal conductor composition comprising:
 (a) 35 to 94 wt % solder alloy powder selected from the group consisting of (i) SAC solder alloy powder consisting of tin, silver, and copper alloy powder, wherein said tin is greater than 90 wt % of said SAC solder alloy powder, (ii) solder alloy powder consisting of tin and bismuth alloy powder, wherein said tin is at least 40 wt % of said tin and bismuth alloy powder, and (iii) mixtures thereof, said alloy powder consisting of particles possessing an average particle size of 2 to 18 μm and a surface area/mass ratio in the range of 0.2 to 1.3 m 2 /g; 
 (b) 1 to 30 wt % metal selected from the group consisting of silver, copper, gold, aluminum and mixtures thereof, said metal consisting of particles possessing an average particle size of 2 to 18 μm and a surface area/mass ratio in the range of 0.1 to 2.3 m 2 /g; and 
 (c) 5 to 35 wt % organic medium comprising:
 (1) a resin that is a vinyl co-polymer resin of vinylidene chloride and acrylonitrile or a phenoxy resin; dissolved in 
 (2) organic solvent comprising a dibasic ester or glycol ether; 
 
 wherein if said resin is a phenoxy resin said metal is silver, wherein said solder alloy powder and said metal are dispersed in said organic medium and wherein the wt % of said solder alloy powder, said metal and said organic medium are based on the total weight of the polymer thick film conductor composition; 
   C) applying said polymer thick film conductor composition onto said substrate; and   D) subjecting said polymer thick film conductor composition to photonic sintering to form said electrical conductor.   
     
     
         7 . The electrical device of  claim 6 , said method further comprising a step of drying said polymer thick film conductor composition, wherein said step of drying is carried out following step (C) but before step (D).