Tin electroplating solution and tin electroplating method

Abstract

To provide a tin electroplating solution devoid of harmful lead and having excellent solder wettability, and a method for depositing a tin film on electronic parts using such a tin electroplating solution. The tin electroplating solution includes organic acids, a naphtholsulfonic acid and, as needed, an antioxidant and a surfactant is disclosed.

1 . A tin electroplating solution comprising one or more compounds for supplying stannous ions, one or more organic acids and one or more of 2-naphthol-7-sulfonic acid and salts thereof.  
   
   
       2 . The tin electroplating solution of  claim 1 , wherein the one or more organic acids is selected from the group consisting of alkane sulfonic acid and alkanol sulfonic acid.  
   
   
       3 . The tin electroplating solution of  claim 1 , further comprising one or more of antioxidants and surfactants.  
   
   
       4 . The tin electroplating solution of  claim 1 , wherein the one or more of 2-naphthol-7-sulfonic acid and salts thereof are included in the electroplating solution in amounts of 0.01 g/L to 20 g/L.  
   
   
       5 . The tin electroplating solution of  claim 1 , wherein the electroplating solution contains virtually no lead ions.  
   
   
       6 . A method for electroplating a tin film on a substrate comprising: 
 a) providing a tin electroplating solution comprising one or more compounds for supplying stannous ions, one or more organic acids and one or more of 2-naphthol-7-sulfonic acid and salts thereof;    b) contacting the substrate with the tin electroplating solution; and    c) plating the tin film on the substrate.    
   
   
       7 . The method of  claim 6 , wherein the one or more or 2-naphthol-7-sulfonic acid and salts thereof are included in the electroplating solution in amounts of 0.01 g/L to 20 g/L.  
   
   
       8 . A method for electroplating a tin film on a substrate comprising: 
 a) subjecting the substrate to an activation treatment to form an activated substrate;    b) contacting the activated substrate with a tin electroplating solution comprising one or more compounds for supplying stannous ions, one or more organic acids and one or more of 2-naphthol-7-sulfonic acid and salts thereof; and    c) plating the activated substrate with a tin film.