BLACKENING TREATMENT OF COPPER OR COPPER ALLOY AND BLACKENING TREATMENT LIQUID

摘要

PURPOSE:To obtain a blackened film having good adhesion property to a substrate and coloring reproducibility by treating copper (alloy) in a liquid containing alkali hydroxide, alkali persulfate, complexing agent and oxidizing agent at low temp. CONSTITUTION:A blackening treatment liquid is prepared so that it contains alkali hydroxide such as potassium hydroxide, alkali persulfate such as sodium peroxosulfate, complexing agent, and oxidizing agent. A copper (alloy) substrate is subjected to blackening treatment with this treatment liquid at about 20-50 deg.C by dipping, etc. It is preferable to use in combination one or more compds. selected from phosphate and ammonium salt as the chelating agent and selected from chromate an oxoacid salt as the oxidizing agent.