Synergistic Effect Of Polymer Additives And Chloride Ions On Copper Electrorefining

The synergistic effects of polymer additives such as gelatin and polyethylene glycol) (PEG) and Cl- on Cu electrodeposition have been investigated by measuring the polarization curves for Cu deposition, by rotating ring-disk electrode technique and by AC impedance measurements. The cathode potential for Cu deposition was greatly polarized in solutions containing both Cl- and gelatin or PEG, showing evident synergistic effect of polymer additives and Cl- on Cu deposition. The cathode potential was shifted to the less noble direction with increasing the concentration of Cl- in solutions containing polymer additives and showed the maximum polarization at Cl- concentration range between 0.1 and 1 mmol/L. The rotating ring-disk electrode technique revealed that Cu deposition in solutions containing small amounts of Cl- proceeded with initial formation of adsorbed intermediate CuClad. The Cole-Cole plots obtained by AC impedance techniques suggest that the reduction of CuClad is suppressed by polymer additives. The morphology of Cu deposited from solutions containing both PEG and Cl- showed the compacted surface composed of smaller grains due to an increase in the overpotential for Cu deposition.