Cu-Sn-Ni-Si-Zn系銅合金の析出

概要

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It is generally known in the brass mill industry in Japan that CDA Copper Alloy C64740 (Cu-Sn-Ni-Si-Zn system copper alloy) is used for copper-leadframe material which satisfies high quality requirements corresponding with miniaturization of semiconductor devices.Many studies on precipitation of Cu-Ni-Si system copper alloy have been performed in the past seventy years since M.G. Corson invented it in 1927. However, the precipitation ofCu-SnNi-Si-Zn system copper alloy containing a small content of Ni and, in particular, Si has not been studied, sufficien try.C64740 which is commercially produced shows a very fine structure, and small precipitateshaving maximum length of 1,u m under in the rolled strip, and keeps the precipitates with a good recrystallization even though it is annealed at high temperatures from 723 K to 873 K for 3.6ks, which indicate a possibility to give a favorable fabricating and plating property to leadframes.The precipitates in the alloy aged after solution treatment and cold rolling are finer than those in the alloy aged without cold rolling after solution treatment. Meanwhile, the grains grow rapidly in the solution treatment at 973 K. Therefore, it might be preferable in the production to get the finer precipitates while the grain refining is maintained.