| 摘要 |
An electroplating soln. comprises: (a) at least one monovalent metal complexed with thiosulphate ion; (b) an organic sulphinate stabiliser for the thiosulphinate ion at a pH of less than 7. Also claimed is a pref. electroplating soln. A pref. electroplating soln. contg. metals in amts. of 0.5-100g/l, where the molar ratio of thiosulphate:metal ion of 1-3:1 and a in deionised water: 188 g/l of sodium thiosulphate pentahydrate, 20 ml/l of triethanolamine, 10 g/l of benzene sulphinic acid sodium salt dihydrate, 35 g/l of cuprous sulphate and 2 g/l of a surface active agent. The pH of the bath was adjusted to 5 by the addn. of phosphoric acid. Brass and steel panels were electroplated in the above bath at cathode current densities of 5 amps/sq. foot at 70-75 deg.F. A 7.5 micron, suitably adherent, semi-bright deposit was obtd. after 36 minutes. The bath was then left idle for 2 months, after which it had maintained its initial clear straw yellow colour. |
