Reductive electroless gold plating solution, and electroless gold plating method using the plating solution

Abstract

The present invention has an object to provide an electroless gold plating solution capable of suppressing the corrosion of a substrate metal and realizing excellent wire bondability, and containing no hazardous substance. In order to achieve the object, as a reductive electroless gold plating solution used for formation of an electroless plated gold film on a surface of a plating target by electroless plating, an electroless plating solution containing a water-soluble gold compound, citric acid or a citrate salt, ethylenediaminetetraacetic acid or an ethylenediaminetetraacetate salt, hexamethylenetetramine, and a chain polyamine having an alkyl group having 3 or more carbon atoms and 3 or more amino groups is adopted.

1 . A reductive electroless gold plating solution used for formation of an electroless plated gold film on a surface of a plating target, comprising:
 a water-soluble gold compound; citric acid or a citrate salt; ethylenediaminetetraacetic acid or an ethylenediaminetetraacetate salt; hexamethylenetetramine; and a chain polyamine having an alkyl group having 3 or more carbon atoms and 3 or more amino groups.   
     
     
         2 . The reductive electroless gold plating solution according to  claim 1 , wherein the gold plating solution has a pH of 7.0 to a pH of 9.0. 
     
     
         3 . The reductive electroless gold plating solution according to  claim 1 , wherein the chain polyamine is 3,3′-diamino-N-methyldipropylamine or N,N′-bis(3-aminopropyl)ethylenediamine. 
     
     
         4 . The reductive electroless gold plating solution according to  claim 1 , comprising a thallium compound as a deposition accelerator. 
     
     
         5 . A method of electroless gold plating, comprising forming an electroless plated gold film on a surface of a plating target using the reductive electroless gold plating solution according to  claim 1 . 
     
     
         6 . The method of electroless gold plating according to  claim 5 , wherein one of copper, palladium, gold and nickel is present on the surface of the plating target. 
     
     
         7 . The method of electroless gold plating according to  claim 6 , wherein the surface of the plating target includes an electroless plated palladium film formed on a surface of an electroless plated nickel film. 
     
     
         8 . A plated product, obtained by electroless gold plating by the method of electroless gold plating according to  claim 5 .