Gold plating solution

Abstract

Provided is a cyanide-free non-electrolytic gold plating solution including a specific nitrile compound. The plating solution is sustainable and showed good bath stability and plating performance.

1 . A cyanide free non-electrolytic gold plating solution comprising one or more sources of gold ions and an organic compound represented by the formula (1):
   NC—R  (1)
   wherein R is selected from a linear or branched, substituted or unsubstituted C 1 -C 20  alkyl; a substituted or unsubstituted C 6 -C 10  aryl and -A-X-A′-Y; wherein X is chosen from O, N(R′) or S, Y is chosen from —CN, amide, amino and carboxyl, A and A′ may be the same or different and are linear or branched, substituted or unsubstituted C 1 -C 20  alkylenes and R′ is hydrogen or substituted or unsubstituted, linear or branched C 1 -C 20  alkyl; and with the proviso that a carbon atom alpha to —CN is not substituted with hydroxyl and when the carbon alpha to —CN is substituted with an amine group, the remaining hydrogen of the alpha carbon is further substituted.   
     
     
         2 . The gold plating solution of  claim 1 , wherein the organic compound is selected from the compounds represented by the formula (2) to (14), 
       
         
           
           
               
               
           
         
         wherein n is a integer from 1 to 10. 
       
     
     
         3 . The gold plating solution of  claim 1 , further comprising sodium sulfite. 
     
     
         4 . The gold plating solution of  claim 1 , wherein the gold source is selected from gold chloride, gold sulfite and gold thiosulfite. 
     
     
         5 . The gold plating solution of  claim 1 , wherein the concentration of the organic compound represented by the formula (1) is from 0.1 to 5 g/L. 
     
     
         6 . A method for forming a gold film on an article according to  claim 1 , comprising the step of contacting the article with a solution comprising one or more sources of gold ions and an organic compound represented by the formula (1). 
     
     
         7 . An article having a gold film on its metal surface, wherein the gold film is formed from the gold plating solutions of  claim 1 . 
     
     
         8 . The article of  claim 7 , wherein the metal surface is selected from the group consisting of copper, nickel, cobalt, silver, palladium and a metal alloy containing copper, nickel, cobalt, silver and palladium.