Anti-corrosive treatment of copper - in chromium - contg a soln

摘要

Copper strip is cathodically treated in an aq. electrolyte contg. 0.4-0.6 gpl hexavalent Cr ions (calcd. as CrO3) using a cathode current density of 0.21-0.43 A/dm2 and a residence time of 6-8 secs. Spec. the strip is conducted continuously through the electrolyte along a sinuous path hving anode plates arranged on each side. Corrosion resistance partic. to sulphide is enhanced, with a reduction in spot and stain formation without any detrimental effect on adherence to substrate, solvent resistance of interface adhesive or solderability when used in printed circuit mfe.