Indium electroplating compositions and methods for electroplating indium on nickel

Abstract

Indium electroplating compositions electroplate substantially defect-free, whisker-free, uniform indium layers which have a smooth surface morphology on nickel. The indium electroplating compositions are environmentally friendly and include select amino acids to provide for the smooth, uniform and defect-free indium deposits.

What is claimed is: 
     
         1 . An indium electroplating composition consisting of water; one or more sources of indium ions; one or more acids selected from the group consisting of inorganic acids, alkane sulfonic acids, and salts of the acids, wherein the inorganic acids are selected from the group consisting of sulfamic acid and sulfuric acid; and one or more amino acids selected from the group consisting alanine, arginine, aspartic acid, asparagine, glutamic acid, glycine, glutamine, leucine, histidine, lysine, threonine, isoleucine, serine, and valine; optionally one or more alloying metal; and optionally one or more pH adjuster. 
     
     
         2 . The indium electroplating composition of  claim 1 , wherein the one or more amino acids are selected from the groups consisting of glycine, arginine, lysine, glutamine, serine, histidine and asparagine. 
     
     
         3 . The indium electroplating composition of  claim 1 , wherein the one or more amino acids are in amounts of at least 5 g/L. 
     
     
         4 . The indium electroplating composition of  claim 3 , wherein the one or more amino acids are in amounts of 10 g/L to 200 g/L. 
     
     
         5 . The indium electroplating composition of  claim 1 , wherein the one or more acids are inorganic acids selected from the group consisting of sulfamic acid and sulfuric acid. 
     
     
         6 . The indium electroplating composition of  claim 1 , wherein the one or more alloying metals is selected from the group consisting of tin, silver, bismuth and copper. 
     
     
         7 . A method of electroplating indium on nickel comprising:
 a. providing a substrate comprising a nickel layer adjacent to a copper or copper alloy layer;   b. contacting the substrate comprising the nickel layer adjacent to the copper or the copper alloy layer with an indium electroplating composition consisting of water; one or more sources of indium ions; one or more acids selected from the group consisting of inorganic acids, alkane sulfonic acids, and salts of the acids, wherein the inorganic acids are selected from the group consisting of sulfamic acid and sulfuric acid; and one or more amino acids selected from the group consisting alanine, arginine, aspartic acid, asparagine, glutamic acid, glycine, glutamine, histidine, leucine, lysine, threonine, isoleucine, serine, and valine; optionally one or more alloying metal; and one or more pH adjuster; and   c. electroplating an indium layer adjacent to the nickel layer of the substrate with the indium electroplating composition.   
     
     
         8 . The method of electroplating indium on nickel of  claim 8 , wherein the indium layer is greater than 0.1 μm. 
     
     
         9 . The method of electroplating indium on nickel of  claim 8 , wherein the indium layer is 0.2-1 μm. 
     
     
         10 . The method of electroplating indium or indium alloy of  claim 10 , wherein the one or more amino acids are selected from the groups consisting of glycine, lysine, glutamine, histidine, serine, asparagine and arginine.