Abstract Electroplating bath for the electrodeposition of tin-nickel alloys, approximating 65% by weight of tin and 35% by weight of nickel, said alloy being deposited over a wide range of current density, from a bath consisting essentially of (i) nickel sulfamate concentrate sufficient to give about 10 ounces of nickel per gallon, and (ii) ammonium bifluoride to the amount of about 1 pound per gallon, and (iii) stannous fluoride sufficient to give about 4 ounces of tin metal per gallon. The bath is strongly self-buffered to a pH 4.3 to 4.5, but operable in the pH range of 4.0 to 5.5. Said bath is operable to place the said amount of tin and nickel at any temperature about 60° C at a current density from 0 up to and exceeding 40 amperes per square foot when temperature is in the range of 74° to 77° C. The deposit is bright, of low compressive stress, and exhibits an extraordinary resistance to corrosion.
An aqueous electroplating bath for plating an alloy consisting substantially of 65 weight percent tin and 35 weight percent nickel, said bath consisting, per gallon of bath, of a. 1/2 gallon of an aqueous solution containing about 20-22 ounces per gallon of said solution of nickel in the form of nickel sulfamate, and b. 1/2 gallon of an aqueous solution containing about 1/3 pound of stannous fluoride and about 1 pound of either ammonium bifluoride or ammonium fluoride, said plating bath incorporating a buffering agent consisting of ammonium sulfamate which is formed in situ on mixing of solutions A and B, to give a pH in the range of 4.0 to 5.5.
Claim 2
Dependent Claim
112 words
An aqueous electroplating bath for plating an alloy consisting substantially of 65 weight percent tin and 35 weight percent nickel, said bath consisting, per gallon of bath, of a. 1/2 gallon of an aqueous solution containing about 20-22 ounces per gallon of said solution of nickel in the form of nickel sulfamate, and b. 1/2 gallon of an aqueous solution containing about 1/3 pound of stannous fluoride and about 1 pound of either ammonium bifluoride or ammonium fluoride, said plating bath incorporating a buffering agent consisting of ammonium sulfamate which is formed in situ on mixing of solutions A and B, to give a pH in the range of 4.0 to 5.5.