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Proceedings Paper

Fabrication of integrated microlens array mold and mold insert for mass production
Author(s): Ruey Fang Shyu; Feng-Tsai Weng; Chengtang Pan; Hsiharng Yang
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Paper Abstract

This article describes a mass fabrication method for integrated microlens arrays mold by using UV lithography, thermal reflow, and electroforming process. The designed microlens array can be used for back light modules to enhance panel illumination. Refractive microlens with diameter 30 and 70 mm in array are designed in certain layout. Lithographic fabrication of photoresist cylinder is applied by using the designed microlens array patterns. Thermal reflow resulted in photoresist melting and diameter shrinkage. Due to surface tension the shape of the photoresist cylinders changes to spherical shape. The sags of microlens with diameter 30 and 70 mm are 7.5 and 25 mm, respectively. The cross-section profile of microlens is measured by the Taylor Hobsons profiler. It proved that thermal reflow can produce microlens array in photoresist materials. Replication process is applied by using electroforming process. Ni-Co composite electroforming can make metallic mold with hardness Hv 500 which is close to ordinary mold materials. Sputtering silver as a seed layer is applied onto microlens array in photoresist. Electroforming can start a build-up process to make required microlens array mold or mold insert. Refractive microlens arrays with high dense 700 lenses per mm2 were fabricated. The surface roughness of microlens arrays is less than Ra 0.02 mm that adapt to the conventional lens surface roughness. Since the higher accuracy and lower cost of microlens fabrication methods are needed to meet the rapid growth of micro-optical devices, the contributed fabrication techniques are essential for the industry.

Paper Details

Date Published: 10 September 2002
PDF: 8 pages
Proc. SPIE 4928, MEMS/MOEMS Technologies and Applications, (10 September 2002); doi: 10.1117/12.483153
Show Author Affiliations
Ruey Fang Shyu, National Huwei Institute of Technology (Taiwan)
Feng-Tsai Weng, National Huwei Institute of Technology (Taiwan)
Chengtang Pan, Industrial Technology Research Institute (Taiwan)
Hsiharng Yang, National Chung Hsing Univ. (Taiwan)


Published in SPIE Proceedings Vol. 4928:
MEMS/MOEMS Technologies and Applications
Guofan Jin; John S. McKillop; Kazuhiro Hane, Editor(s)

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