Patent ID: 6749738
Filing Date: 2004-06-15
Classification: C25D,H05K,Y10T

Abstract:
An electrochemical method for producing an inorganic covering layer on a surface of a copper or copper-based alloy element, said method comprising the steps of:(a) providing an electrolytic bath comprising a single alkali salt in aqueous solution, said bath having a concentration of about 1.25-11.25 mole/l of hydroxyl ion; (b) subjecting said element to anodic oxidation by placing said surface in the electrolytic bath under controlled process conditions of temperature and current density for a period of time suitable to form a continuous homogeneous layer of copper (I) oxide on said surface, wherein said layer has a thickness of 0.100-0.400 &mgr;m and a crystalline structure, and wherein said current density is applied in a range of 0.5-20 A/dm2 to form the layer with a brown color, a dark brown color or a deep black color and a velvety surface effect.