Direct electroless silver plating on copper metal from a succinimide complex bath using imidazole as the reducing agent was examined. Though the electroless silver plating from this bath is essentially an autocatalytic deposition, there is a problem in the properties and adhesion of the plated film because of the substitution deposition of silver due to the dissolution of the base copper metal that occurs during the first stage of plating. By adding glyoxylic acid, which is catalytically reacted on the copper surface to emit electrons, as the second reducing agent, the substitution deposition of silver was suppressed, the surface condition became dense and the adhesion was improved. It has been determined that the mixed potential theory can be applied to this reaction based on the result of the local polarization curve measurement.
