氣輔UV壓印技術製作透鏡陣列及其應用

一般LED封裝多以點膠式單顆或數顆分批進行，透鏡另加套，若能以壓印進行晶圓級封裝，並直接將透鏡結構結合透明封裝體上，效率必大幅提升；此外，微透鏡在雙面均有光學形貌，一般是以射出成型製造，若能以大面積壓印進行，成本必大幅下降。由於紫外光固化成型技術不需升降溫過程，可於室溫下進行施作，製程簡單快速，本研究以紫外光固化技術製作透鏡陣列結構，分別開發兩種製程，一為紫外光固化技術應用於LED晶圓級封裝，另一為雙面微透鏡陣列結構之製作。本研究第一部分開發以紫外光固化技術製作透鏡陣列，並將其應用於LED晶圓級封裝的製程，直接將透鏡製作於封裝體，達到大面積快速的效果。首先先探討紫外光固化膠體塗布方法，就旋轉塗布與刮刀塗佈進行參數探討，發現膠體使用刮刀塗布法，刮刀速度0.17mm/s下可完整充填透鏡模穴並無氣泡。為使透鏡結構均勻，使用氣體施壓的方式進行LED封裝製程，並探討氣體壓力對於透鏡轉印結果影響，實驗結果發現氣體壓力於2.5psi下轉印出的透鏡結構高度最佳，其轉寫率達98.9%。本研究成功於4吋矽晶圓上製作出25×25透鏡陣列進行晶圓級封裝。本研究更進一步利用紫外光固化技術製作雙面微透鏡陣列結構，簡化傳統雙面結構製作，並減少殘留應力。此雙面透鏡開發製程可以簡易步驟製造雙面微透鏡陣列，且所製作出三種微透鏡陣列結構，雙凸、雙凹及一凹一凸皆可有良好的成型性，透鏡轉印率達92.3%。本研究證實氣輔壓印紫外光固化技術應用於LED晶圓級封裝及雙面微透鏡陣列製作的可行性。

關鍵字

紫外光固化；晶圓級封裝；氣體輔助轉印；雙面微結構

並列摘要

Wafer level LED packaging with lens structure can enhance the efficiency of packaging by integrating lens profile on the package and increasing the covered LED numbers in one operation. The packaging technique needs to be developed. On the other field, the lenses for the image acquisition system in smart wearable devices demand thin dimension and high performance. Lens array with various concave/convex surfaces can achieve such requirements. The fabrication technique has to be efficient. This study is devoted to the development of UV imprinting technique to fabricate lens array for those two applications: LED wafer level package and lens array with double-sided convex/concave profiles. The first part of this study is devoted to LED wafer level packaging by gas-assisted UV imprinting. PDMS mold is made by casting PDMS on electroplated Ni mold with micro-lens array. Spin-coating and doctor blade method were used to coat UV-curable resin onto the PDMS mold. It was found the doctor blade method could coat UV resin perfectly with the blade moving at a velocity of 0.17 mm/s. The gas-assisted UV imprinting process was then employed for packaging 25×25 lens array on a 4" wafer. The results showed that homogeneous lens array with 98.9% height replication can be achieved with a gas pressure of 2.5 psi. The UV imprinting is used to fabricate double-sided micro lens array in the second part of this study. Lenses with convex surfaces on both sides, concave surfaces on both sides, and convex on one surface / concave on the other surface were fabricated. Homogeneous lens shape with 92.3% height replication were successfully fabricated with this process. This study proves that UV imprinting can be used for LED wafer level package and double-sided micro lens array fabrication.

並列關鍵字

UV curing ； wafer-level package ； gas-assisted ； double side structure

參考文獻

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[5] P. Dannberg, R. Bierbaum, L. Erdmann, and A. Braeuer, "Wafer scale integration of micro-optic and optoelectronic elements by polymer UV reaction molding, "Proc. of SPIE, Vol. 3631, pp. 244-251 (1999)

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氣輔UV壓印技術製作透鏡陣列及其應用

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