流體微熱壓製程開發研究

Development of Fluid-Based Heating and Pressing Systems for Micro Hot Embossing

張哲豪(Jer-Haur Chang)

指導教授 ： 楊申語

國立臺灣大學/工學院/機械工程學研究所/博士(2004年)

https://doi.org/10.6342/NTU.2004.10133

摘要

本論文主要探討大面積塑膠薄膜微熱壓(Hot Embossing)製程並提出新熱壓方法。首先使用傳統熱壓機進行薄膜熱壓實驗探討。研究發現薄膜的表面微結構成型，其成型技術遠比板件困難；須加一層軟襯墊材料，使母版與塑膠薄膜能緊密貼合，以精確轉寫表面微結構。不定形塑膠成型性遠比半結晶型塑膠好，軟襯墊材質選擇重要。
傳統塑膠微熱壓製程，藉壓板機構來加熱加壓有缺陷。壓板施壓會導致壓力分佈不均，複製面積不大且精度受限；而脆性材料(如矽晶圓、玻璃)不宜當模具，受壓容易發生破裂。此外，壓板(熱盤)加熱冷卻，需將整塊熱盤升溫及降溫，製程耗時且浪費能源。為解決目前製程的缺點與限制，本論文提出新的流體微熱壓方式。利用流體等向、等壓的物理特性，以流體微熱壓來取代傳統壓板式熱壓。使用的工作流體計有：氣體、蒸汽、熱煤油等。在加壓方面，因使用流體直接進行熱壓工作，可達到完整均勻壓力分佈、大面積、不壓破矽晶圓之目的；在加熱方面，因工作流體或熱輻射體直接加熱及冷卻模腔內部待熱壓物，也可達到快速加熱冷卻之幼纂C
實驗結果顯示，以流體熱壓可完整的轉寫複製出四吋、十二吋晶圓微結構，而且矽晶圓模具未被壓破，證明了此新微熱壓方法可均勻加壓且可使用脆性模具材料的特性。此外，流體熱壓微結構確實在升降溫速度上遠較傳統壓板電熱式快，例如：蒸汽30秒內即可迅速加熱至130℃。流體加熱冷卻可節省能源、縮短成型週期，有效提升微熱壓成型製程的產能。
此外，本文亦使用ANSYS有限元素分析軟體，成它a將傳統熱盤、蒸汽快速加熱、熱煤油快速加熱與遠紅外線加熱等新製程，建立成數值熱傳模型。得以分析新製程之加熱速率、加熱均勻性，並與實驗值互相比較驗證。分析結果與實驗量測結果接近，曲線趨勢吻合，數值模型可以作為流體加熱冷卻製程預測利器。

關鍵字

流體 ； 快速加熱冷卻 ； 氣體 ； 大面積 ； 晶圓 ； 微熱壓 ； 熱壓 ； 微結構

並列摘要

This thesis is devoted to the development new system and process for large-area hot embossing. First, a series of hot embossing experiments were conducted to transcript the micro U-groove features in a stamper onto large thin thermoplastic films with traditional hot press. Film embossing is found different from plate embossing in applying slight pressure during heating and backing the stamps with cushion pads. The formability of amorphous PC films was found to be much larger than that of the semi-crystalline PET films.
During conventional hot embossing, the substrate and the stamp are brought into contact and are compressed directly by the hot plates of the machine. The accuracy and area of replication are limited due to the inherent non-uniform pressure distribution. Si-wafers are too brittle to be used as embossing tools with the conventional hot embossing operation.
In this study, three innovative methods of rapid heating and uniform pressing for micro hot embossing were developed. Fluids were used as heating and pressing media. With these three systems, the temperature of substrate rises rapidly and uniform pressure is exerted over the whole substrate. The working fluids used in this experiment included steam, gas, and oil. In addition, rapid heating through far infrared radiation (FIR) was also implemented with a gas pressurized hot embossing process. It was found that a 0.2 millimeter-thick PVC substrate can be heated from 25oC to 130oC in 30 seconds using steam heating, in only 25 seconds using FIR heating, and in 3.5 minutes using oil heating. The heating speeds of all three methods are much faster than those using conventional hot-plate heating, which takes more than 10 minutes. Successful replications of micro-features onto 4-inch and 12-inch substrates have been achieved.
The simulations of heat transfer in these new processes are also carried out with finite element software of ANSYS. Heat transfer analysis proves helpful in predicting temperature response and in the design of process.

並列關鍵字

hot embossing ； rapid heating ； fluid ； gas ； wafer

參考文獻

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