Electrolytic copper-stripping liquid and electrolytic stripping method

Abstract

The present invention provides an electrolytic copper-stripping liquid free from a cyan compound, which comprises a copper compound or an aromatic nitro compound as a copper-oxidizing agent, and which has a pH of from 9 to 12. Also disclosed is an electrolytic stripping method using the electrolytic stripping liquid.

1 . An electrolytic copper-stripping liquid free from a cyan compound, which comprises a copper compound or an aromatic nitro compound as a copper-oxidizing agent, and which has a pH of from 9 to 12.  
     
     
         2 . The electrolytic copper-stripping liquid according to  claim 1 , wherein the copper compound is a copper ammonium complex derived from: 
 an ammonium source selected from the group consisting of ammonia water and an ammonium salt; and    a copper source selected from the group consisting of copper sulfate, copper carbonate, copper oxalate and copper hydroxide.    
     
     
         3 . The electrolytic copper-stripping liquid according to  claim 1 , further comprising at least one compound selected from the group consisting of phosphoric acid and salts thereof, organic acids and salts thereof, carbonates, hydrogencarbonates, and amino carboxylic acids and salts thereof.  
     
     
         4 . The electrolytic copper-stripping liquid according to  claim 1 , further comprising, as a stripping agent for silver, a compound that reacts with silver to form a complex.  
     
     
         5 . The electrolytic copper-stripping liquid according to  claim 4 , wherein the compound that reacts with silver to form a complex is pyridinecarboxylic acid, a thiocyanic acid salt, dimethylhydantoin, or succinic acid imide.  
     
     
         6 . The electrolytic copper-stripping liquid according to  claim 1 , further comprising a surfactant.  
     
     
         7 . The electrolytic copper-stripping liquid according to  claim 6 , wherein the surfactant is a polyoxyethylene chain-containing surfactant or a fluorine-containing surfactant.  
     
     
         8 . An electrolytic copper-stripping method comprising electrolytically stripping a copper plating film exposed from a silver plating film that partially covers a copper plating film formed on the entire surface of a member, using the electrolytic copper-stripping liquid according to  claim 1 , 
 wherein the member is dipped in the electrolytic copper-stripping liquid and is used as an anode.    
     
     
         9 . The electrolytic copper-stripping method according to  claim 8 , wherein an electrode made of a metal which does not elute in the electrolytic stripping liquid is used as a cathode.  
     
     
         10 . The electrolytic copper-stripping method according to  claim 8 , wherein the member is a lead frame made of an iron based alloy material.