TIN-SILVER-COPPER PLATING SOLUTION, PLATING FILM CONTAINING THE SAME, AND METHOD FOR FORMING THE PLATING FILM

摘要

A tin-silver-copper containing plating solution which comprises a medium having water as its primary component, a sulfonic acid, a tin ion, a copper ion and a silver ion, wherein concentrations of the silver ion, the tin ion and the copper ion are 0.015 to 0.1 mol/L, 0.21 to 2 mol/L and 0.002 to 0.02 mol/L, respectively; a plating film which comprises 2.6 to 3.4 wt % of silver, 0.4 to 0.7 wt % of Cu and the substantially balanced amount of tin; an electrolytic plating method for use in forming the above plating film from the above plating solution; and a soldering method using the plating film. The plating solution exhibits high stability, and the plating film has a low melting point.