| 摘要 |
PROBLEM TO BE SOLVED: To easily clean the surface without generating smut by allowing the electrolytic etching soln. of a precipitation-hardening copper alloy product to contain an alkali metal carbonate and a complexing agent and to have a specified anode current efficiency at specified pH. SOLUTION: A precipitation-hardening copper alloy product is etched with an electrolytic etching soln. to clean its surface. The etching soln. contains 5-50% alkali metal carbonate plus complexing agent, the pH is controlled to 9-13, and the etching proceeds with a low anode current efficiency. Citric acid, ethylenediamineacetic acid, etc., or their alkali metal salt are appropriately used as the complexing agent. Further, the anode current density of etching is preferably controlled to 1-30A/dm<2> and the etching amt. to 0.1-1μm.
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