Brightening composition for zinc alloy electroplating bath and its method of use

Claim 1

An aqueous zinc alloy electroplating bath having a pH of from about 0 up to about 6.5 and comprising about 7 to about 165 g/l zinc ions, at least one of nickel ions and cobalt ions individually present in an amount of about 1 to about 60 g/l, about 0.5 to about 200 mg/l aluminum ions, and an effective amount of a brightener comprising a bath soluble polymer of the formula: ##STR2## wherein: Y may be the same or different and is R or RX, where R is H or C 1-10 aliphatic radical, where X is H, OH, COOR 1 , COON[R 1 ] 2 , SO 3 M, CN, N[R 1 ] 2 or OR 1 , where M is H or a Group I or II metal; R 1 is H or C 1-4 alkyl radical; and n is 2 to 2,000,000; and copolymers of said polymer and a solubilizing agent present in an amount up to 25 mole percent of the copolymer selected from the group consisting of methacrylic acid, acrylic acid, acrylonitrile, methacrylonitrile, vinyl C 1-5 alkyl esters, vinyl halide, epihalohydrin, vinulidine halide, alkylene oxide and mixtures thereof.