High conductivity inks with improved adhesion

Abstract

Conductive ink compositions which can be cured to highly conductive metal traces by means of “chemical welding” include adhesion promoting additives for providing improved adhesion of the compositions to various substrates.

1 . A method for preparing a solid metal conductor on a substrate comprising the steps of: 
 (a) mixing a reactive organic medium, a metal powder or flake, and an adhesion promoting agent;    (b) applying the mixture formed in step (a) onto the substrate; and    (c) heating the substrate at a critical temperature less than 450° C. for a time less than about 20 minutes;    wherein the applied mixture is converted into a well-consolidated well-bonded pure metal conductor.    
   
   
       2 . The method of  claim 1 , further comprising roll milling the mixture of (a) to produce a homogeneous composition.  
   
   
       3 . The method of  claim 1 , wherein the metal powder has an average particle size of from 0.05 to 15 μm.  
   
   
       4 . The method of  claim 1 , wherein the reactive organic medium is a metallo-organic decomposition compound, an organic reactive reagent which can form a metallo-organic decomposition compound upon reaction with the metal constituent or a mixture thereof.  
   
   
       5 . The method of  claim 1 , wherein the mixture is applied by printing.  
   
   
       6 . The method of  claim 5 , wherein the printing technique is selected from screen printing, rotary screen printing, gravure printing, intaglio printing, flexographic printing, letterpress printing, lithographic printing, ink jet printing or electrostatic printing.  
   
   
       7 . A method for preparing a solid pure metal conductor on a substrate comprising the steps of: 
 (a) mixing (i) a metallo-organic decomposition compound; 
 (ii) a metal flake or powder in an amount 1 to 20 times the amount of the metallo-organic decomposition compound by weight; and  
 (iii) an adhesion promoting additive in the amount 0.05 to 2.0 times the amount of the metallo-organic decomposition compound by weight;  
   (b) printing the mixture formed in step (a) onto the substrate; and    (c) heating the substrate at a critical temperature less than 450° C. for a time less than about 20 minutes;    wherein the printed mixture is converted into a well-consolidated well-bonded pure metal conductor.    
   
   
       8 . The method of  claim 7 , further comprising roll milling the mixture to produce a homogeneous composition.  
   
   
       9 . The method of  claim 7 , wherein the metal powder has an average particle size of from 0.05 to 15 μm.  
   
   
       10 . The method of  claim 7  wherein the mixture is printed by a method selected from screen printing, rotary screen printing, gravure printing, intaglio printing, flexographic printing, letterpress printing, lithographic printing, ink jet printing or electrostatic printing.  
   
   
       11 . The method of  claim 7 , wherein the substrate is selected from polyester, polyimide, paper or epoxy.  
   
   
       12 . The method of  claim 11 , wherein the polyester substrate is polyethylene terephthalate or polyethylene naphthalate.  
   
   
       13 . The method of  claim 7 , wherein the adhesion promoting additive is a polymer selected from polyvinylidene chloride, polyvinyl chloride, polyethylene vinyl chloride, polyester, or copolymers thereof.  
   
   
       14 . The method of  claim 7 , wherein the adhesion promoting additive is a primary diamine.  
   
   
       15 . The method of  claim 7 , wherein the adhesion promoting additive is a polymer selected from low T g  polyimides, silicones, fluorocarbons, fluoropolymers, soluble (chain extending) polyimides, polyimideamides, polyamic acids, or combinations thereof.  
   
   
       16 . The method of  claim 7 , wherein the metal is silver powder or flake.  
   
   
       17 . The method of  claim 16 , wherein the adhesion promoting additive is a polymer selected from polyvinylidene chloride, polyvinyl chloride, polyethylene vinyl chloride, polyester or copolymers thereof.  
   
   
       18 . The method of  claim 17 , wherein the mixture is printed onto a polyester substrate.  
   
   
       19 . The method of  claim 16 , wherein the adhesion promoting additive is a primary diamine.  
   
   
       20 . The method of  claim 19 , wherein the mixture is printed onto a polyester substrate.  
   
   
       21 . The method of  claim 7 , wherein the metal is copper powder or flake.  
   
   
       22 . The method of  claim 21 , wherein the adhesion promoting additive is a polymer selected from low T g  polyimides, silicones, fluorocarbons, fluoropolymers, soluble (chain extending) polyimides, polyimideamides, polyamic acids, or combinations thereof.  
   
   
       23 . The method of  claim 22 , wherein the mixture is printed onto a polyimide substrate.