Selective catalytic activation of non-conductive substrates

Abstract

A process of providing a pattern of a metal on a non-conductive substrate to create loop antennae for wireless articles, for creating circuitry for smart cards, such as phone cards, and for providing electromagnetic shielding of electronic devices is provided. The method comprises the steps of catalyzing the non-conductive substrate by applying a catalytic ink, reducing a source of catalytic metal ions in the catalytic ink to its associated metal, depositing electroless metal on the pattern of catalytic ink on the surface of the substrate; and plating electrolytic metal on the electroless metal layer to produce the desired pattern of metal on the non-conductive substrate. The catalytic ink typically comprises one or more solvents, a source of catalytic metal ions, a crosslinking agent, one or more copolymers, a polyurethane polymer, and, optionally, one or more fillers.

1 . A method of plating on a non-conductive substrate, the method comprising the steps of: 
 a) applying a catalytic ink to at least a portion of a surface of the non-conductive substrate, wherein the catalytic ink comprises: 
 i) a solvent;  
 ii) a source of catalytic metal ions;  
 iii) a crosslinking agent;  
 iv) a copolymer; and  
 v) a polyurethane polymer;  
   b) reducing the source of catalytic metal ions to its associated metal with a suitable reducing agent; and    c) plating metal on the catalytic ink applied to the portion of the surface of the non-conductive substrate.    
     
     
         2 . The method according to  claim 1 , wherein the catalytic ink is applied by screen printing, gravure, lithography or flexography.  
     
     
         3 . The method according to  claim 1 , wherein the solvent is selected from the group consisting of aromatic and aliphatic hydrocarbons, glycerol, ketones, esters, glycol ethers, and esters of glycol ethers.  
     
     
         4 . The method according to  claim 3 , wherein the solvent is selected from the group consisting of toluene, xylene, glycerol, methyl ethyl ketone, cyclohexanone, butyl acetate, dioctyl phthalate, butyl glycolate, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, ethylene glycol acetate, propylene glycol monomethyl ether-acetate, acetone, isophorone, methyl propyl ketone, methyl amyl ketone, diacetone-alcohol, and combinations of the foregoing.  
     
     
         5 . The method according to  claim 4 , wherein the solvent is cyclohexanone.  
     
     
         6 . The method according to  claim 1 , wherein the catalytic metal ions are selected from the group consisting of palladium, gold, silver, platinum, copper, and combinations of the foregoing.  
     
     
         7 . The method according to  claim 6 , wherein the catalytic metal ions comprise palladium.  
     
     
         8 . The method according to  claim 7 , wherein the source of palladium is selected from the group consisting of palladium dichloride and palladium acetate.  
     
     
         9 . The method according to  claim 8 , wherein the source of palladium is a solution of about 10% to about 20% palladium dichloride in water with hydrochloric acid.  
     
     
         10 . The method according to  claim 8 , wherein the source of palladium is a solution of about 0.1% to about 2% palladium acetate in cyclohexanone.  
     
     
         11 . The method according to  claim 1 , wherein the crosslinking agent is a polyisocyanate.  
     
     
         12 . The method according to  claim 1 , wherein the copolymer comprises vinyl chloride and hydroxylpropyl acrylate.  
     
     
         13 . The method according to  claim 1 , wherein the catalytic ink comprises one or more fillers selected from the group consisting of talc, oxides of manganese, titanium, magnesium, aluminum, bismuth, copper, nickel, tin, zinc, and silicon, silicates, bentonites, chalk, carbon black, and combinations of the foregoing.  
     
     
         14 . The method according to  claim 13 , wherein the one or more fillers comprise talc and fumed silica.  
     
     
         15 . The method according to  claim 1 , wherein the non-conductive substrate is selected from the group consisting of polyimides and polyethylene terephthalate.  
     
     
         16 . The method according to  claim 1 , wherein the source of catalytic metal ions is reduced to its associated metal with a reducing agent selected from the group consisting of sodium borohydride, hydrazine, hydrazine hydrate, hydrazine sulfate, and dihydrazine sulfate.  
     
     
         17 . The method according to  claim 16 , wherein the reducing agent is sodium borohydride.  
     
     
         18 . The method according to  claim 1 , wherein the metal is selected from the group consisting of electroless copper, electroless nickel, and combinations thereof.  
     
     
         19 . The method according to  claim 18 , wherein the metal is electroless copper.  
     
     
         20 . The method according to  claim 1 , wherein the metal is plated to a thickness of about 0.5 to 1.5 microns.  
     
     
         21 . An electromagnetic interference coated substrate produced by the process of  claim 1.