ELECTRIC HIGH PURITY TIN OR TIN ALLOY PLATING BATH AND PROJECTION ELECTRODE FORMED BY THE PLATING BATH

摘要

PROBLEM TO BE SOLVED: To suppress the generation of voids when a projection electrode is formed with tin or specified tin alloy plating.;SOLUTION: Provided is an electrolytic high purity tin or tin alloy plating bath comprising: (A) the soluble salt of high purity tin with a purity of 99.99% or higher and the soluble salt made of the stannous salt and a mixture of the salt of a metal selected from silver and copper; and (B) a thioalkane type or oxyalkylene type specified aliphatic sulfide compound. Since the specified sulfide compound is added and the stannous salt of high purity tin is used, among β-tins in the tin based film composing a projection electrode, the orientation index of a specified crystal face group such as a {431} face group and a {411} face group is made higher than a prescribed one and the crystal face group is made parallel to the surface of the base, a film having reduced voids can be formed at the crystal grain boundaries of β-tin, and the generation of voids is suppressed, guessingly.;COPYRIGHT: (C)2015,JPO&INPIT