| 摘要 |
PROBLEM TO BE SOLVED: To obtain a copper alloy material excellent in stress relaxation resistance and equivalent or superior to phosphor bronze in balance between tensile strength and elongation, peeling of Sn plating, whisker formation in Sn plating layer, stress corrosion cracking sensitivity, etc. SOLUTION: The copper alloy material has a composition consisting of 3-<4% Sn, 0.5-1.0% Ni, 0.05-5.0% Zn, and the balance copper with inevitable impurities, and further, the total content of substances unentered into solid solution, such as precipitates, is regulated to <=0.02%. This material can be manufactured by carrying out, in the course of cold rolling, heat treatment consisting of holding at 550-700 deg.C for 5 sec to 5 min and successive cooling at >=5 deg.C/sec cooling rate down to ordinary temperature, performing cold rolling to the desired size, and then subjecting the sheet to stabilizing annealing at 325 to 450 deg.C for 5 sec to 180 min.
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