Barrel plating or high-speed rotary plating using a neutral tin plating solution

Abstract

A barrel plating or high-speed rotary plating method for electronic components, and a neutral tin plating solution used therein. A plating solution that includes (A) stannous ions, (B) an acid or a salt, (C) a complexing agent, and (D) a diamine that has a polyoxyalkylene chain, and that has a pH in a range between 4 and 8 is used. The use of this neutral tin plating solution prevents the electronic components from coupling together during the barrel plating, enabling an improvement in manufacturability in barrel plating.

What is claimed is: 
     
         1 . A barrel plating or high-speed rotary plating method for electronic components, including a step for barrel plating or high-speed rotary plating of an electronic component using a tin plating solution that includes (A) stannous ions, (B) an acid or a salt, (C) a complexing agent, and (D) a diamine that has a polyoxyalkylene chain, and wherein the pH is in a range between 4 and 8. 
     
     
         2 . The method as set forth in  claim 1 , wherein barrel plating is carried out with a current density between 0.05 and 0. 
     
     
         3 . The method as set forth in  claim 1 , wherein the electronic component is selected from a capacitor, an inductor, a thermistor, and a varistor. 
     
     
         4 . A neutral tin plating solution for barrel plating or high-speed rotary plating comprising:
 (A) stannous ions;   (B) an acid or a salt;   (C) a complexing agent; and   (D) a diamine having a polyoxyalkylene chain, wherein a pH is in a range between 4 and 8.   
     
     
         5 . The neutral tin plating solution for barrel plating or high-speed rotary plating as set forth in  claim 4 , wherein the diamine having the polyoxyalkylene chain has a molecular weight between 200 and 1100.