Fabrication of cone-like microstructure using UV LIGA-like for light guide plate application

The microlens array is usually formed by thermal reflow of polymer disks and can be one microstructure of the light guide plate (LGP). Here, we propose an ultraviolet (UV) backside exposure technology to fabricate the photoresist cone-like microstructure on the PMMA substrate at room temperature and then use UV LIGA-like process to transfer the microstructure for the application of 3.6 in. (72 mm x 57.5 mm) LGP. The electroforming was used to transfer UV master mold to the inverse cone-like microstructure of nickel metal mold and then hot embossing was used for one more pattern transfer to the same cone-like microstructure on PMMA substrate. The optical microscope and alpha-stepper profiler were used to examine the morphology and profile of LGP microstructure. The optical luminance and uniformity of LGP were measured using BM9 luminance meter in comparison with commercial product. The light uniformity and luminance of the cone-like LGP microstructure reach 75-80% and 2,800-3,000 cd/cm(2), respectively which meet the requirements of commercial LGP.