| 摘要 |
PROBLEM TO BE SOLVED: To impart a plating film having solder wettability equivalent to that of a tin-lead alloy plating bath or higher by incorporating trace eutectoidable different metal ions into Cu. SOLUTION: The plating bath preferably has the following composition: 5 to 100 g/l Sn2+ ions, 0.05 to 20 g/l Cu2+ ions (or Cu+) ions, 0.5 to 30 g/l nonionic interfacial active agent and 0.01 to 10 g/l different metal ions. The different metal ions are preferably Ni2+, Fe2+, Zn2+ and Ag+. Even if the composition in the bath is excessively small or excessively large, the assurance of good solder wettability in the plating film is difficult, and if the bath is excessively large, the crystal grain refining of the plating film progresses further and the film cures, leading to the degradation in the secondary fabricatabiity of the plating film. The plating bath regulated to a pH to <6 is used and for this purpose, alkane sulfonic acid, etc., and inorganic acid, for example, sulfuric acid, etc. are adequately used.
|
