Fabrication Process Of 3D Micro Mold Cavity Based On UV-LIGA And EDM Technology

As the rapid development of MEMS technology, microfluidic chip has become the focus in the areas of life science, chemical etc. Hot embossing and micro injection technologies are used broadly in the fabrication of microfluidic chip, in which the structure of micro flow channel is influenced directly by the structure of micro mold cavity. UV-LIGA technology is commonly used in the fabrication of micro mold cavities with vertical sides, but is not fit for fabricating 3D microstructures. So the research on fabrication process of 3D micro mold cavity is significant for the development of microfluidic chip.In order to fabricate micro metal mold cavity with 3D structures locally, this paper introduces a new combined fabrication process. Firstly, fabricate 2D microstructure on a metal plate applying UV-LIGA technology, and then transform local 2D microstructure into 3D figure applying sinking EDM (electro-discharge machining) technology. The reshaped location is according to the design of micro mold.This paper firstly introduces the present application situation of UV-LIGA and EDM technology in the fabrication of metal micro mold cavities. To fabricate the microfluidic chip mold with vertical sides, academic and experimental research on backless board growing process is done. The process includes SU-8 lithography and micro electroforming Ni mainly. At the same time, some special questions in the process are analyzed and corresponding solutions are adopted.The basic theory of sinking EDM is introduced, including the model of material removal mechanism, the discharge gap state, the mechanism of tool electrode wear and its influencing factors, and the characteristic analysis of small area electrical discharge machining. Directed by the basic theory, experimental research on sinking EDM to fabricate 3D micro mold cavity is done applying ordinary electrical discharge machining tool. Firstly, the upright sides of micro mold cavity are transformed into slope sides locally using special tool electrode in the repeated machining way. And then some incipient experimental research is done to fabricate micro mold cavity with curving surface structure using a tool electrode with micro semicircular structure.In order to measure the surface roughness after sinking EDM, evaluation method for small area surface is enacted. To decrease the surface roughness of EDM, the influencing factors including pulse parameters and process conditions were analyzed. According to the result measured by 3D surface profile, the surface roughness Ra of slope sides 0.4μm.