移動式感應加熱氣體輔助熱壓製程開發

熱壓印成型製程簡單、模具及機台成本低和轉寫率高，常用來複製高分子生醫及光學元件的表面微結構。傳統熱壓印成型有兩大問題:第一是板壓容易造成壓力分佈不均; 第二是升降溫耗時導致製程時間長。本研究使用氣體施壓，使壓力均勻; 並使用包覆式感應加熱技術，使升溫快速。為了避免直接感應加熱微結構模具，開發金屬夾心PDMS模具，微結構在PDMS上，夾心金屬受感應加熱。為了使加熱面積不受線圈和功率限制，本研究開發模具移動裝置，達到更大面積的快速加熱;也進一步以風冷強制對流散熱，解決降溫耗時的問題，開發出快速大面積升降溫且均壓的微結構熱壓設備。本研究首先利用COMSOL分析軟體，模擬包覆式線圈對SUS 420不鏽鋼板感應加熱的表面升溫，觀察在不同模具移動模式下的加熱趨勢; 接著實驗驗證，藉由調整不同區域的停留時間和速度，提升整體溫度均勻性。移動式感應加熱可使面積80×80 mm2的不鏽鋼板在36 s內由40℃升溫到210℃，且溫差小於20℃。本研究設計製造直徑195 mm，長221 mm的壓力腔體，將不鏽鋼板夾心PDMS模具、移動式平台及感應加熱線圈裝置其內，實際壓印23.5 "μm" 寬、48.6 "μ" m高的週期性V-cut 微結構於長寬厚80×80×0.18 mm3的PC板上，轉寫率可達95%以上，生產週期時間少於4 mins。微結構壓印Fresnel lens以及DOE繞射元件的成品皆有良好的光學成像，證實移動式感應加熱氣體輔助熱壓應用於微結構熱壓印的潛力。

關鍵字

熱壓印成型；氣體輔助施壓；移動式感應加熱； PDMS模具熱壓；繞射元件

並列摘要

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.

並列關鍵字

Moving Induction heating ； Hot embossing ； Gas-assisted pressuring ； PDMS mold ； DOE

參考文獻

[7] 鄭芳松, “氣體輔助PDMS模具壓印製程開發研究.”臺灣大學博士論文, 2007.

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[4] P. W. Leech, R. A. Lee, and T. J. Davis, “Printing via hot embossing of optically variable images in thermoplastic acrylic lacquer,” Microelectron. Eng., vol. 83, no. 10, pp. 1961–1965, 2006.

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移動式感應加熱氣體輔助熱壓製程開發

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