| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of whiskers on a tin based film and the occurrence of cracks on a bismuth film in a double layer plating in which the tin based film is formed through the bismuth base. SOLUTION: In the method for preventing tin whiskers, in a method where the object to be plated is electroplated using a pretreatment liquid comprising a soluble bismuth salt, and a base film of bismuth is formed on the surface of the object to be plated, and a plating film of tin or a tin alloy is formed on the bismuth base, the film thickness of the bismuth base is controlled to <0.4μm. Whiskers can effectively be prevented even if the tin based film is formed on the extremely thin bismuth film of <0.4μm, and further, the hard bismuth film can extremely thinly be formed, so that the occurrence of cracks on the bismuth film is prevented, and the exertion of a harmful effect upon the tin based film as the upper layer can be checked. COPYRIGHT: (C)2004,JPO
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