抄録
The decomposition mechanism of gold sulfite plating baths was investigated and stabilizing agents were evaluated with a view to improving bath stability. It was confirmed that Au metal and Au3+ ion were produced at bath decomposition, which proceeded based on a 3Au+→2Au+Au3+ disproportionation reaction. This shows bath stability will be improved by inhibiting the disproportionation reaction and the most effective agents that were inhibiting the dispropotionation of Au+ and thus improving bath stability were 2, 2'-dipyridyl and its derivatives including 0-phenanthroline and neocuproin. The Vickers hardness of the deposit from baths containing 2, 2'-dipyridyl was 66Hv, and the stress was lower than for the standard bath. Brightness was improved by the addition of As3+, but hardness and stress were increased.
