| 摘要 |
PROBLEM TO BE SOLVED: To allow a copper alloy to sufficiently be applied even to a multipin lead frame or the like by controlling the crystal grain size of an alloy contg. specified ratios of Zn and Si, moreover contg. at least one kind among Bi, Se, Ca, Sr and rare earth elements by specified ratios in total, and the balance Cu with inevitable impurities to the specified one. SOLUTION: The crystal grain size of a copper alloy contg., by weight, 5 to 35% Zn and 0.5 to 3% Si, furthermore contg. at least one kind among Bi, Se, Ca, Sr and rare earth elements by 0.001 to 0.5% in total, and the balance Cu with inevitable impurities is preferably controlled to 5 to 35μm. This copper alloy uses a Cu-Zn alloy as a base, and stress corrosion cracking as its weak point is improved by adding a suitable amt. of Si and optimumly controlling the crystal grain size therein. Zn improves its punching workability. Bi, Se, Ca, Sr and rare earth elements moreover improve the punching workability. Furthermore, Si contributes to the improvement of its strength, and the optimization of the crystal grain size improves its bending workability.
|
