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Significance Statement
In this study, an optimal demolding scheme which can minimize the maximum stress of microstructures during demolding has been identified through numerical simulations by using the explicit dynamic finite element analysis (FEA) solver, LS-DYNA. Due to the time-step consideration for the explicit FEA, a scale-up modeling approach is used to reduce the computational time for the simulations. The experimental results from the developed prototypes of the rotating arm and roller based peel demolding systems have also been obtained which agree with the findings from numerical simulations. For the microstructures with lower aspect ratio, the effect of the peel demolding method may not be significant. However, for patterns included high-aspect-ratio micro pillars, the approach to peel the thin film off the mold becomes a critical step for successful demolding. Because of the difficulty in real time measurement of the deformation as well as the stress-strain of the micro pillars during the demolding process, the numerical models provide valuable information to better understand the dynamics of the flexible multibody motion and also offer insights into the approaches which can improve the yield rate of the systems. From this study, the roller based demolding method is identified as the optimal approach in our analysis cases which can minimize the distortion and collapse of the micro pillars. The yield rate of the roller based demolding system can be up to 99% based on our experimental study.
Journal Reference
Chih-Hsing Liu 1, Wenjie Chen2, Wen Su2, Chen-Nan Sun2
[expand title=”Show Affiliations”]- Department of Mechanical Engineering, National Cheng Kung University, Tainan, 701, Taiwan
- A*STAR-Singapore Institute of Manufacturing Technology, Singapore, 638075, Singapore
Abstract
This study aims to investigate two peel demolding schemes through numerical simulations and experimental studies in order to improve the yield rate of the automated system for demolding of the polydimethylsiloxane (PDMS) micropillars with aspect ratio of 6. Numerical models based on the explicit dynamic finite element analysis by using LS-DYNA are developed to identify an optimal demolding scheme which can minimize the maximum stress of microstructures during demolding. A scale-up modeling approach is proposed to increase the numerical time-step for microscale problems in order to reduce the computational time. The experimental tests are also carried out which agree with the findings from numerical simulations. From this study, the roller-based demolding system is identified as the optimal approach in our analysis cases which can minimize the distortion and collapse of micropillars. The yield rate of the roller-based demolding system in our experimental study can be up to 99 %.
Go To The International Journal of Advanced Manufacturing Technology
