Additive for zinc-copper electroplating baths - based on a buffer and nickel or cobalt ions, to obtain finely granular undercoatings

摘要

Additive for Zn-Cu electroplating baths comprises a mixt. of a buffer such s boric acid, alkali metal borate, alkali metal carbonate, alkali metal phosphate and/or glycine, and Ni or Co ions. The mixt. is used in forming undercoatings onto which other metals are deposited, the Zn-Cu coating being smooth and finely granular such that it does not appear through the top coating.