Electrodeposition is extremely effective for applying uniform thin metal coatings on a complex microdevices, which otherwise are inaccessible by other coating techniques. We are actively developing electrical contact coatings for Ni-based microsystem using the LIGA* microfabrication process
, Fig. 1. The requirements for the coating are high strength, wear resistance and good adhesion to the Ni substrate. The candidate coating that meets these criteria is electrodeposited Au coating (referred to here as Hard Au), plated from a commercial sulfite electrolyte with organic additive (Technigold 25E). In this study, we focus on the metallurgical factors that determine the strength of the Au coating material and influence adhesion of the Au coating to the Ni microsystem substrate.