Electrochemical finishing of nickel microstructures

One method to manufacture high aspect ratio metallic microstructures is the LIGA technique. The acronym LIGA stands for the German words for lithography, electroforming and moulding. A resist layer (e.g. PMMA) is structured using deep X-ray lithography. The resist is developed and the resulting mould is filled with metal by electroplating. Though electroplating is an essential part of the LIGA process there are still challenges concerning the deposit surfaces. Nevertheless, extremely precise metal structures can be manufactured. In particular, the sidewall surface quality can be in the sub-micrometer range. But due to irregularities during the deposition process, resulting in rough or wavy surfaces, the emerging surface does not meet required tolerances. For this reason, a finishing process is necessary. Electrochemical techniques such as electroor plasmapolishing have been evaluated. Electropolishing, a common anodic dissolution technique widely used in industry to obtain smooth, bright and burr-free surfaces, as well as plasmapolishing, also a technique based on the anodic dissolution are presented. First results of both an electropolished and a plasmapolished nickel microstructure are reported.