ELECTROLYTIC PEELING AGENT FOR SILVER AND ELECTROLYTICALLY PEELING METHOD

摘要

PURPOSE:To electrolytically peel an unnecessary plated silver film without impairing substrate metal by keeping this substrate metal having the plated silver film to be peeled in an aq. soln. contg. both succinic acid imide or phthalic acid imide and alkali metal hydroxide as an anode and allowing current to flow. CONSTITUTION:An Ag strike plating layer 2 is formed on one part of a lead frame 1 made of Cu alloy and a glossy Ag plating layer 3 is formed on one part of the Ag strike plating layer 2. The test piece is immersed in the peeling liquid for plating having the following composition and the lead frame 1 is kept as an anode and DC voltage is impressed at 3-15V between the anode and a cathode made of stainless steel and current is allowed to flow at 0.1-5A/dm<2> anodic current density. Thereby only the Ag strike plating layer 2 is electrolytically peeled without impairing the substrate metal 1 made of Cu alloy and the glossy Ag plating layer 3. As the utilized electrolytic peeling liquid, the electrolytic peeling liquid which contains 10-100g/l complexing agent of succinic acid imide and phthalic acid imide system, 3-12g/l conductive agent of alkali metal hydroxide such as NaOH and pH buffering agent such as boric acid and has 6-9.5pH is utilized.