Hot Embossing of Microstructure with Moving Induction Heating and Gas-Assisted Pressuring

• Main Authors: Ching-Chieh Kao, 高經傑
• Other Authors: 楊申語
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/44a675

碩士 === 國立臺灣大學 === 機械工程學研究所 === 105 === Hot embossing is a low cost and flexible method for fabricating micro/nano structures on the polymer. However, there are two problems in the conventional hot embossing process. First, the heating by the platens causes long cycle time. Second, the pressure provided by the platens is not uniform. In many studies, induction heating has been used to increase the heating rate in the hot embossing process. However, heating area is greatly limited by the size of the induction coil and the power of induction heater. In this study, moving induction heating was proposed and demonstrated. In addition, gas-assisted pressuring was employed to provide uniform embossing pressure. The PDMS mold with the microstructure on its surface and SUS 420 plate in the center as the insert was made. A mechanism was designed and implemented to move the platform in and out the wrapped coil, on which the sealed box for mold/substrate was placed. A chamber of 195 mm diameter and 221 mm length was machined. The movable platform, the sealed box with mold/substrate stack, wrapped coil and cooling fan were all implemented in the gas chamber. The wrapping coil can heat the PDMS mold with SUS 420 plate insert from 40℃ to 210℃ in 36 s. The periodic V-cut structures with depth of 23.5 "μ" m and height of 48.6 "μ" m can be replicated on PC substrate using this moving induction heating and gas-assisted pressuring hot embossing. Replication rates were all above 95% and the cycle time was less than 4 mins. Other microstructures for Fresnel lens and DOE structures were also successfully replicated. This study proves the potential of this moving induction heating and gas-assisted pressuring hot embossing for fast fabrication of microstructure onto polymeric substrates.