Understanding and improving the uniformity of electrodeposition

A new method namely the wire beam electrode (WBE) has been employed as a means of characterising electrodeposition uniformity. The influences of several electroplating parameters including the geometry of bath, the concentration and movement of electrolyte, and bath temperature on the uniformity of electroplated coatings have been investigated by mapping local electrodeposition currents and by analysing characteristic patterns in these current distribution maps. With the Watts nickel bath, the general current distribution pattern is such that higher currents were recorded along the edges with the magnitude decreasing in a contour-like manner towards the center of the WBE surface. Lower offset voltages, suitable amount of bath agitation, elevated temperatures, appropriate cathode–anode separation and bath concentration were found to contribute to the enhancement of current distribution uniformity when they were assessed individually. However, combining these plating parameters did not produce the expected synergistic effect in uniformity improvement.