PURPOSE: To obtain a plating bath to form a tin alloy coating film having excellent soldering property by preparing a plating bath of a low melting point tin alloy comprising Sn2+ ion, metal ion such as Ag+, and a nonionic surfactant and containing no lead.
CONSTITUTION: A plating bath of a low melting point tin alloy is prepared so that the bath contains Sn2+ ion (tin methanesulfonate, tin isopropanolsulfonate, or the like) and one or more kinds of metal ions such as Ag+ ion (silver methanesulfonate), Cu2+ (copper methanesulfonate), In3+ (indium methanesulfonate), Tl+ (thallium methanesulfonate), Zn2+ (zinc methanesulfonate), and a nonionic surfactant (12mol ethylene oxide adduct of nonylphenol ethoxylate), and contains no lead. By using the obtd. plating bath of the low melting point tin alloy, a tin alloy film having excellent appearance and soldering property can be formed.
MURAMATSU YOSHIAKI
DOI KANAE
YADA YOSHIHIKO
