感應加熱帶輪微熱壓製程及其在光學用微結構複製的應用

Replication of Large-area Microstructures using Induction heated Belt Pulley Embossing

陳奕衡(Yi-Heng Chen)

指導教授 ： 楊申語

國立臺灣大學/工學院/機械工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201803647

摘要

熱壓印成型為複製高分子微結構元件常用的製程技術，其具有製程步驟簡單、轉寫率高、模具機台成本較低的優勢。傳統熱壓印成型有二大問題：一是板壓，容易造成壓力分佈不均；二是升降溫耗時，成型週期過長。本研究利用滾輪施壓的方式，可突破腔體的面積限制，僅需調整滾輪左右壓力並搭配平台移動即可達到大面積均壓，相對於板壓需要調整平面二方向，可大幅減少其調整的時間。為了達到快速升降溫的目的，本研究藉由感應加熱一不鏽鋼帶，並傳熱至模具使基材軟化，因鋼帶厚度僅不到1 mm，能夠減低將整個模具感應加熱所需的能量與時間。
感應加熱的關鍵元件是線圈，為了解線圈對鋼帶的加熱狀況，先利用模擬軟體預測薄鋼帶在單面式線圈加熱下的升溫趨勢，並配合實驗進行驗證。分析結果顯示框型的線圈與本研究所需的溫度分布最為一致，其溫度分布趨勢也與實驗結果相當符合。經實際升溫顯示，於壓印點的溫差可控制在10°C以內，證明此機台設計可達到良好的溫度均勻性。本研究接著將帶輪式感應加熱與滾對版熱壓製程結合，設計製作可快速升降溫且具備滾輪施壓之設備，實驗結果顯示設備所需時間大幅縮短，於2分鐘內即可完成
在實際應用上，此製程能完整複製100 mm × 100 mm微米結構於PETG、PMMA基材表面，所複製的V型溝槽及為透鏡陣列皆可達到95%以上的轉寫率，並透過照度量測，驗證所製作的V型溝槽能夠有52%的增亮效果。本研究證明高週波感應加熱結合滾輪施壓應用於壓印微結構的可行性與性能。

關鍵字

熱壓印成型 ； 滾對板施壓 ； 感應加熱 ； 微結構複製

並列摘要

Hot embossing is a popular technology for fabrication of polymer micro-structured components. It has the advantages of simple steps, high replication rate, and low cost. Traditional hot embossing has two major problems: First, it easily causes uneven pressure distribution; second, the cycle time is too long. In this study, roller is employed to apply uniform pressure along the contact line. By simply adjusting pneumatic pressure applying in the two sides of shaft of the roller and by moving with the platform through the roller, large-area uniform embossing pressure can be achieved. In order to achieve rapid heating, a stainless steel belt is heated by induction heater right before entering the roller, and to heat the mold upon contact.
First, a simulation software is used to predict the heating rate and distribution of temperature of the heated thin steel belt during the heating of the single-side coil. The analysis results show that the coil with frame shape is the most suitable for the induction heating of the belt, and its temperature distribution is also quite satisfactory. Second, experiments of induction heating of the belt are setup and carried out. The measured temperature difference at the embossing point can be controlled within 10 °C. This proves that the design can achieve good temperature uniformity. Then a facility, in which the induction heating integrated with the belt belly hot embossing, is designed and constructed. The experimental results show the cycle time required replication of microstructures can be reduced to less than 2 minutes.
Two microstructures, V-cut and microlens array have been replicated onto the surface of PETG and PMMA substrates of 100 × 100 mm2. The transcription rate of 95% can be achieved. The illumination measurement has shown that the brightness of the plates with V-cut has increases 52%. This study demonstrates the feasibility, performance and potential of induction heated belt pulley roller embossing for replication of microstructures.

並列關鍵字

hot embossing ； belt pulley ； induction heating ； microstructure replication

參考文獻

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