Stoichiometry of Anodic Copper Dissolution at High Current Densities

'l'he influence· of current density, flow rate and electrolyte composition on the stoichiometry of anodic copper dissolution was investigated under conditions comparable to those of electrochemical machining. Weight loss measurements, x-ray diffraction and chemical analysis were used for the characterization of the dissolution reaction. A sharp change in dissolution mechanism.coincidedwith the transition from active to transpassive dissolution. For active dissolution, an apparent valence of the dissolution process of two was found in sulfate and nitrate electrolytes; and of one in chloride electrolytes. For transpassive dissolution, mixed valences lying between 1 and 2 were found in all electrolytes. The mixed valences are interpreted to result from the simUltaneous production of monovalent and divalent reaction products, some of which are in solid form.