An automated demolding system for PDMS microstructures with high aspect ratio

This paper presents a roller-based peel-off demolding method and system for demolding of the polydimethylsiloxane (PDMS) micro pillars with high aspect ratio (6:1). The method can reduce the maximum stress exerted on the microstructures during the step of separating the PDMS film from the mold. Therefore the yield rate can be greatly increased. In this paper, the peel-off demolding process has been analyzed, and the major failure mode of the process is identified as the lateral collapse of the micro pillars. The effects of several process parameters (such as cycle time, sample thickness and temperature) on yield rate are identified. A lower demolding speed, larger thickness and lower temperature of the sample can yield better results. A prototype of the automated demolding system has been developed. The experimental results show that the system can achieve stable results with 99% yield rate.