| Summary: | 博士 === 國立交通大學 === 機械工程系 === 91 === The photoresist, NANOTM XP SU-8, has been implemented in the fabrication of high-aspect-ratio microstructures in low-cost MEMS production. However, the reachable thickness of the electroplated structures standing on the substrate were limited to 50 mm below due to the internal force and deformation of the photoresist in final stripping process. In this study, using SU-8 as an electroplating mold, an embedded root method is proposed to consolidate the adhesion of the plated microstructures to the substrate. By constructing the embedded root as a substructure, this novel technique can greatly increase the thickness of the metal components, and simultaneously, the hard-to-strip crosslinked SU-8 may be removed completely. A side-driven electrostatic micromotor is employed as an example to demonstrate the effectiveness of the proposed method, where the structural height and the minimum gap of the stator poles are 300 mm and 50 mm, respectively. For comparison, some fabricated results of typical approaches by a heated remover to strip the cured SU-8 mold are also shown in this thesis. In addition, a systematically experimental investigation on this method is conducted to characterize the relationship among the root depth, the line-width, and the allowable thickness of the electroplated structures. Based on the established relationship between the root depth and the geometric sizes, a 3-D Ni coil with 200 mm in thickness, 80 mm in width, and 4 mm in root depth is successfully released by the SU-8 mold with 400 mm in height, which can not be achieved by the standard SU-8 molding process. The process parameters presented herein may be applied to the fabrication of other thick metal microstructures with similar needs.
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