Ultra-precision Machining of Micro-step Pillar Array Using a Straight-Edge Milling Tool

Abstract

Ultra-precision machining has been well known as a very precise and effective way to prototype and fabricate different types of components with microstructures. In this paper, an ultra-precision micro-milling method has been presented to produce a micro-step pillar array as an embossing mold for semiconductor application. Theoretical analysis on machining mechanics indicates that work material property, machining strategy, and cutting tool geometry largely affect machining distortion on the machined microstructure. Experimental investigation has been conducted on micromachining of the micro-step pillar array using different types of cutting tools and work materials. Experimental results demonstrate that the material property, cutting tool edge radius, and cutting force play a significant role in the machined micro-structure accuracy and surface finish, while grain boundary of brass has no significant effect on the micro-milling performance. The best outcome among the tests done is achieved when using brass as work material and cutting with a straight-edge single crystalline diamond tool. The main reasons to achieve this outcome are based on: the brass material having a higher elastic modulus and the diamond tool having a smaller cutting edge radius, which contributes to better machinability of brass. One micro-step pillar array has been successfully obtained with very precise feature and dimensional accuracy using brass work material and single-crystal diamond tool. It is believed that the outcomes of this study would largely benefit the research community and end-users.