High Speed Electrodeposition of Copper from Conventional Sulphate Electrolytes

Abstract

A rotating cylinder cathode cell has been developed to examine parameters affecting high rates of deposition in copper sulphate based electrolytes. Initial electrochemical measurements have shown that the rate of mass transfer and prevailing hydrodynamic conditions may best be related in terms of dimensionless numbers: St = 0·169 Sc^−0·67 Re^−0·34 where St, Sc and Re are the Stanton, Schmidt and Reynolds numbers respectively. Limiting current densities of up to 174 mA/cm² (162 A/ft²) have been attained for 1500 rev/min in 0·07M solution. The microstructures were characterized by scanning electron microscopy and the same systematic growth mode occurred at all conditions. At current densities greater than 0·7 i_L tree-like or dendritic growths tended to form but for deposit thicknesses less than 2 μm this only becomes significant for currents close to the limiting value.