SILVER-PLATED MATERIAL FOR LEAD FRAME EXCELLENT IN SOLDER WETTABILITY

摘要

PROBLEM TO BE SOLVED: To obtain a silver-plated copper alloy material for a lead frame excellent in solder wettability. SOLUTION: A copper or copper alloy sheet strip is subjected to silver plating so that a*+b* value of the L*a*b* color system prescribed in JIS Z 8729 is 1.5 to 7. The thickness of the silver-plated layer is adjusted to 0.5 to 10μm. The middle between the copper or copper alloy sheet strip and the silver-plated layer has preferably a nickel or nickel alloy-plated layer.