| 摘要 |
PURPOSE:To provide a uniformly etched surface to an Al alloy substrate for a magnetic disk by pickling the substrate with a soln. contg. phosphoric acid and boric acid each at a specified concn. when the substrate is pretreated before electroless plating. CONSTITUTION:An Al alloy substrate for a magnetic disk is pretreated by degreasing, pickling and metal substitution treatment before electroless plating. In the pickling stage, the substrate is pickled by immersion in a soln. contg. phosphoric acid and boric acid each at 5-50g/l concn. The pickling temp. is about 20-60 deg.C, preferably about 30-40 deg.C and the pickling time is >=about 2min, preferably about 3-7min. Thus, a uniformly etched surface is provided to the substrate, and a uniform and dense metallic film as a base for electroless plating can be formed by the following metal substitution treatment. |
