Method for manufacturing lead frames and lead frame material for semiconductor device

摘要

The present invention is related to a method for manufacturing lead frames and a lead frame material including an intermediate layer and a top layer. The intermediate layer is composed of a layer of nickel-cobalt alloy having 5 to 30 wt. % of cobalt and a thickness of 3 to 20 microinches and a layer of nickel or nickel alloy having a thickness of 10 to 80 microinches. The intermediate layer can inhibit the diffusion of the base metal to the surface of the leads. The top layer consisting of gold or gold alloy, which is composed of gold and at least one metal selected from the group consisting of palladium, silver, tin and copper and has at least 60 weight percent gold, has a thickness of 0.1 to 5 microinches.