ELECTROCHEMICAL STUDY OF ELECTROLESS GOLD-DEPOSITION REACTION

The electroless (autocatalytic) gold-deposition reaction, using potassium borohydride as the reducing agent, was studied by electrochemical methods. The results support the assumptions made previously that the species that reduces aurocyanide ions is BH//3OH** minus , an intermediate formed during the hydrolysis of BH//4** minus , and the deposition reaction is preceded by competitive adsorption of reacting species. The hydrolysis kinetics of borohydride ions, under conditions of the electroless process, was also studied using a polarographic method. The results allowed the calculation of rate constants and the variation of concentrations of BH//4** minus and BH//3OH** minus as a function of time during operation of the electroless plating bath.