Direct Electroless Palladium Plating on Copper

Abstract

A method of providing a direct electroless palladium deposit on a copper surface is described. The method comprises the steps of (a) catalyzing the copper surface by applying a pre-dip composition to the copper surface, the pre-dip composition comprising a reducing agent; and thereafter (b) contacting the catalyzed copper surface with an electroless palladium composition to deposit a layer of palladium on the copper surface.

What is claimed is: 
     
         1 . A method of providing an electroless palladium deposit on a copper surface, the method comprising the steps of:
 a) catalyzing the copper surface by applying a pre-dip composition to the copper surface, the pre-dip composition comprising a reducing agent; and thereafter   b) contacting the catalyzed copper surface with an electroless palladium composition to deposit a layer of palladium on the copper surface.   
     
     
         2 . The method according to  claim 1 , wherein the reducing agent comprises a boron reducing agent. 
     
     
         3 . The method according to  claim 2 , wherein the boron reducing agent is selected from the group consisting of alkyl boranes, amine boranes, borane complexes, boron hydride compounds and combinations of one or more of the foregoing. 
     
     
         4 . The method according to  claim 3 , wherein the amine borane is selected from the group consisting of trialkylamine boranes, straight chain methoxy-substituted dimethylamine boranes, N-alkyl substituted morpholine boranes and combinations of one or more of the foregoing. 
     
     
         5 . The method according to  claim 4 , wherein the amine borane comprises dimethylamine borane (DMAB). 
     
     
         6 . The method according to  claim 1 , wherein the pre-dip composition is maintained at a temperature of between about 20° C. and about 30°. 
     
     
         7 . The method according to  claim 6 , wherein the pre-dip composition is maintained at about room temperature. 
     
     
         8 . The method according to  claim 1 , wherein the copper surface is contacted with the pre-dip composition for between about 30 seconds and about 2 minutes. 
     
     
         9 . The method according to  claim 1 , wherein the concentration of the reducing agent in the pre-dip composition is between about 2 and about 20 g/L. 
     
     
         10 . The method according to  claim 9 , wherein the concentration of the reducing agent in the pre-dip composition is between about 5 and 15 g/L. 
     
     
         11 . The method according to  claim 10 , wherein the concentration of the reducing agent in the pre-dip composition is between about 8 and about 10 g/L. 
     
     
         12 . The method according to  claim 1 , wherein no additional process steps are performed between steps a) and b).