Methodology And Device For High Aspect Ratio Micro-injection Molding

With the rapid development of micro/nano technology, polymer micro deviceshave been widely used in biomedical, e-communications, aerospace and other fields.There are a variety of micro-fabrication methods for micro/nano parts manufacture.However, these methods have some shortcomings, such as complex process, hard forrepeated batch production, low efficiency and high cost. All these shortcomings haveseverely limited the development of micro/nano technology. But, the micro-injectionmolding which has been widespread could solve the shortcomings.However, the development of micro-injection molding technology is not perfect,theories and processes of conventional injection molding are not fully applicable tomicro-injection molding. It still faces many problems unsolved, for high aspect ratio ofplastic components, to achieve complete filling of mold cavity and eliminate releasedefects are problems to be solved.To solve the problem that difficult to full fill the mold cavity of high aspect ratiomicro-needle arrays, the methodology and equipment to improve the quality to fillingwere studied, and the near-infrared heating system and vacuum system were designedbased on the study. To solve the release defects of high aspect ratio micro-needle arrays,such as bending, breaking, the forces during inapt mold release were analyzed and theimprovement method of mold release was proposed.In this paper, the developmental assistive devices and mold were tested by themicro-injection molding experiments of high aspect ratio micro-needle arrays. It wasfound that near-infrared heating system could improve the length by15.67%, it had agreater role in promoting the filling ability of micro-needle (Ф0.1mm with aspect ratio5:1) while the vacuum system had no significant effect. All micro-injection moldedmicro-needle had no defect with the improved mold release method, the method couldeliminate the release defects effectively.