To provide a high-strength and high-conductivity copper alloy excellent in migration resistance by forming a Cu-Zn alloy layer on the surface of a Cu-Ni-Si type copper alloy containing specific amounts of Ni and Si.
A Cu-Zn alloy layer is formed on the surface of a Cu-Ni-Si type copper alloy having a composition consisting of, by weight, 0.4-5.0% Ni, 0.1-2.0% Si, and the balance Cu with inevitable impurities. At this time, the ratio of the sheet thickness of the Cu-Zn alloy layer to the sheet thickness of a final product is regulated to 3-20%, and also the Zn concentration in the surface of the Cu-Zn alloy layer is regulated to 10-50wt.%. By this method, the high-strength and high-conductivity copper alloy excellent in migration resistance can be obtained without deteriorating electric conductivity.
YAMAMOTO YOSHINORI
SHIMADA TAKESHI
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