Plating compositions and processes

Abstract

A gold or gold alloy plating composition comprises: a source of gold ions such as potassium gold (I) cyanide; optionally a source of alloying metal (e.g. nickel or cobalt) ions, for example as a sulphate; optionally a complexing agent for the alloying metal ions if present, such as citic acid or oxalic acid; and a rate promoting additive compound of general formula IA or IB: ##STR1## wherein: each of R.sup.1 and R.sup.2 independently represents a hydrogen or halogen atom or a formyl, carbamoyl, C.sub.1-4 alkyl, amino, phenyl or benzyl group, wherein the alkyl, phenyl and benzyl moieties may optionally be substituted with one or more hydroxy or amino groups or halogen atoms; R.sup.3 represents a C.sub.1-6 alkylene radical which may optionally be hydroxylated; and Q represents --SO.sub.2 -- or --CO--. The rate promoter extends the plating current density range of the composition, particularly by reducing or preventing burn at high current densities, and gives a net increase in achievable plating speed for bright deposition.

Dependencies are inferred from the claim text.