| abstract |
PROBLEM TO BE SOLVED: To suppress generation of voids when a bump electrode is formed by tin or specific tin alloy plating. (A) A soluble salt composed of a soluble salt of high-purity tin having a purity of 99.99% or more, and a mixture of the stannous salt and a metal salt selected from silver and copper; (B) An electric high-purity tin or tin alloy plating bath containing a specific aliphatic sulfide compound of thiaalkane type or oxyalkylene type. Since a specific sulfide compound is added and a stannous salt of high-purity tin is used, among the β-tin in the tin-based film constituting the protruding electrode, identification of {431} plane group, {411} plane group, etc. Since the orientation index of the crystal plane group becomes larger than a predetermined value and the crystal plane group becomes parallel to the substrate surface, a film with less voids can be formed at the crystal grain boundary of β-tin, and voids are generated. It is presumed to suppress this. [Selection figure] None |