Fabrication of micro injection mold with modified LIGA micro-lens pattern and its application to LCD-BLU

Jong Sun Kim; Young Bae Ko; Chul Jin Hwang; Jong Deok Kim; Kyung Hwan Yoon

Korea-Australia Rheology Journal, Vol.19, No.3, 165-169, November, 2007

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Fabrication of micro injection mold with modified LIGA micro-lens pattern and its application to LCD-BLU

Jong Sun Kim, Young Bae Ko, Chul Jin Hwang, Jong Deok Kim, and Kyung Hwan Yoon^{1, †}

Precision Mold Team, Korea Institute of Industrial Technology (KITECH), Korea
¹Mechanical Engineering, Dankook University, Korea

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The light guide plate (LGP) of LCD-BLU (Liquid Crystal Display-Back Light Unit) is usually manufactured by forming numerous dots by etching process. However, the surface of those etched dots of LGP is very rough due to the characteristics of etching process, so that its light loss is relatively high due to the dispersion of light. Accordingly, there is a limit in raising the luminance of LCD-BLU. In order to overcome the limit of current etched-dot patterned LGP, micro-lens pattern was tested to investigate the possibility of replacing etched pattern in the present study. The micro-lens pattern fabricated by the modified LiGA with thermal reflow process was applied to the optical design of LGP. The attention was paid to the effects of different optical pattern type (i.e. etched dot, micro-lens). Finally, the micro-lens patterned LGP showed better optical qualities than the one made by the etched-dot patterned LGP in luminance.

Keywords:back light unit(BLU);thin-film-transistor liquid-crystal-display (TFT-LCD);light guide plate (LGP);LIGA;micro-lens;injection molding

[References]

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[1] Becker EW, Ehrfeld W, Hagman P, Mauser A, Munchmeyer D, Microelectron. Eng., 4(1), 35 (1986)

[2] Chang N, Choi I, Shim H, IEEE TRANSACTIONS ON VERY LARGE SCALE INTEGRATION (VLSI) SYSTEMS, 12(8), 837 (2004)

[3] Hwang CJ, Ko YB, Ha SY, Lee GH, Heo YM, 21st Annual Meeting of the Polymer Processing Society (2005)

[4] Lin L, Shia TK, Chiu CJ, J. Micromech. Microeng., 10, 395 (2000)

[5] Lin L, Chiu CJ, Bacher W, Heckele M, 7th International symposium on Micro Machine and Human Science, 67 (1996)

[6] Malek CK, Saile V, Microelectronics Journal, 35, 131 (2004)

[7] Nagahara T, Fukui A, Matsushita Technical Journal, 47(3), 2 (2001)

[8] Popovic ZD, Sprague RA, Connell GAN, Appl. Optics, 27(7), 1281 (1998)

[9] Ruther P, Gerlachy B, Gotterty J, Iliez M, Mohry J, Mullery A, Oßmanny C, Pure Appl. Opt., 6, 643 (1997)

[10] Seidel H, Solid-State Sensor and Actuator Workshop, 4th Technical Digest., IEEE, 86 (1990)

[11] Wu MH, Whitesides GM, J. Micromech and Microeng, 12, 747 (2002)