Pulse reversal plating of nickel and nickel alloys for microgalvanics

Abstract

The use of pulse reversal (PR) plating, as an alternative to the use of additives for electrochemical deposition of nickel, is studied. With optimised pulse plating parameters, and in some cases in combination with additives, substantial improvement of the deposit properties can be achieved. Utilising chloride-type baths, PR plating of pure nickel (and harder nickel–cobalt alloys) have been used to fabricate tools for micro-injection moulding (Polymer Structures for μTas, EuroSensors, Copenhagen, 27–30 August, 2000) and micromechanical structures. Furthermore, preliminary results from pulse plating experiments with ternary magnetic alloys, comprising 50–60% Co, 25–35% Fe and 10–20% Ni, will be reported. For both pure nickel and nickel alloys good chemically stable electrolytes have been developed, and the deposits are smooth with low residual stress. None of the electrolytes contain sulphur co-depositing additives (such as saccharin) nor wetting agents.