| 摘要 |
PROBLEM TO BE SOLVED: To provide a lead wire containing no noxious lead at all and preventing the cracks of palladium plating from reaching a base by plating palladium or its alloy in two layers at a specific thickness by the specific method on the surface of a raw material. SOLUTION: A backing layer 3 of Pd or its alloy plating is directly formed at the thickness 0.1-0.5μm by electroless plating on a lead wire 1 or a metal strand 2, then a surface layer 4 of Pd or its alloy plating is formed at the thickness 0.1-0.5μm. Pd has the intermediate cost between Au and Ag, it is harder than them, it is excellent in the sliding property, and it improves the soldering property and sliding property of the lead wire 1. The backing layer 3 requires a long time for electroless plating, however it is excellent in adhesiveness and abrasion resistance, and it generates no crack. The surface layer 4 requires a short time for electroless plating, and it easily generates cracks when it is heated. Two-layer-plating shortens the relative plating time, and generated cracks do not reach a base. |
