Micro-electrolytic Etching of Ti Base Materials using Impregnating Electrolyte Sheet

A novel electrolytic etching technique using a quasi-solid electrolyte containing LiCl-methanol solution impregnated into a porous polyethylene sheet (1.5-6 mm thick) was proposed, and the characteristics of Ti and TiNi materials using the electrolytic sheet were studied. The electrolyte sheet was sandwiched with the substrate (anode) which was covered with a resist pattern and a Cu (cathode), and then, DC voltages of 4-32 V were applied between the anode and the cathode. Thanks to the slightly wet condition on the PE sheet, the substrate was uniformly etched even though the through holes were non-uniformly distributed on the PE sheet surface. Both Ti and TiNi substrates were similarly etched in this method. The substrate was etched to depth of 50 µm when using stacked thick electrolyte sheets. The etched depth increased with increasing sheet thickness and applied voltage. However, the progress of the etching was saturated within 15 min under all etching conditions. It was found that the draying of methanol during the etching process was one of the factors to prevent the etching.