Paper
5 November 2018 Design of UV LED illumination system for direct imaging lithography
Haibo Jiang, Xiuhui Sun, Ruofu Yang, Jianjun Chen, Lin Xie, Shao-yun Yin
Author Affiliations +
Abstract
UV LED, which is used as the illumination source in the direct imaging (DI) exposure equipment, has the advantages of rich wavelengths and low cost. It has a good application prospect in the field of printed circuit board (PCB) manufacturing. An optical structure of the illumination system for DI lithography, which combines Kohler illumination and double telecentric imaging, is presented. First, the shape of the spot matched with Digital Micromirror Device (DMD) is obtained by setting an aperture at the imaging plane of LED chips to filter out the stray light. Then the aperture is imaged onto the working plane of DMD by the posterior double telecentric lens. The uniform illumination spot without stray light can be achieved on the DMD in the end. In this design, fly eyes are not needed, and the stray light on the DMD surface caused by light outside the effective angle of the LED can be filtered out completely. Based on this idea, a lithographic illumination system with the numerical aperture (NA) of 0.1 is designed and fabricated for 0.95 inch DMD. According to experimental measurements, the effective illumination power is up to 10W, and the illuminance uniformity is more than 85%, which meet the lighting requirements of direct imaging lithography equipment used in PCB manufacturing.
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Haibo Jiang, Xiuhui Sun, Ruofu Yang, Jianjun Chen, Lin Xie, and Shao-yun Yin "Design of UV LED illumination system for direct imaging lithography", Proc. SPIE 10815, Optical Design and Testing VIII, 108150W (5 November 2018); https://doi.org/10.1117/12.2500955
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KEYWORDS
Light emitting diodes

Digital micromirror devices

Lithographic illumination

Imaging systems

Light sources

Lithography

Stray light

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