Developing process for coating copper particles with silver by electroless plating method

Silver–copper composite powders were prepared by electroless plating method in aqueous system at room temperature. The dense and uniform silver coating layer was obtained by strictly controlling the activation and deposition process variables such as: NH4OH/(NH4)2SO4 molar ratio, activation time and feeding rate of silver ion solution. The mechanism of composite powders formation and their characteristics were discussed in detail. It is noted that completely cleansing the oxide layers and protecting the copper particles surface from hydrolysis were key factors to obtain high quality Ag–Cu composite powders.