| 摘要 |
PROBLEM TO BE SOLVED: To improve corrosion resistance, plating treatability, and press blankability by limiting the number of precipitated Fe grains having prescribed major axis in a Cu-Ge-P-Zn alloy of specific composition. SOLUTION: The alloy for lead frame has a composition consisting of, by weight, 1.2-2.2% Fe, 0.005-0.08% P, 0.1-5.0% Zn, and the balance Cu with inevitable impurities, and further, the number of Fe grains of <=10μm major axis in this alloy is regulated to <=5 pieces/mm<2> , preferably <=1 piece/mm<2> . By controlling the contents of Fe and P, a marked effect can be produced on the reduction of the number of >=10#-mm Fe grains. Further, by means of holding at a temp. of (1,180 to 1,250 deg.C) higher by about 100-150 deg.C than the melting point of Cu to melt the Fe added to molten metal completely and application of rapid cooling to the molten metal or an ingot after solidification from the temp., an effect can be produced on the refining of the Fe grains.
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