Silver-electroplating method using thiocyanic solution

摘要

An electroplating method using an aqueous solution containing thiocyanic ions in an amount of 0.5 to 10 moles/l, silver ions in an amount of 0.04 to 0.8 mole/l and a film improving agent in an amount effective to suppress a local growth of a silver film on a metallic substrate to be plated, which comprises subjecting, prior to the electroplating, the metallic substrate to a preplating step under a current density of 0.1 to 80 mA/dm2 in an aqueous solution containing silver ions in an amount of 0.001 to 0.02 mole/l and thiocyanic ions in an amount of 0.1 to 5 moles/l whereby the adhesiveness of the resulting electroplated silver film to the substrate is improved.