Guo-Dung John SU^*, Shao Hsuan HUNG, Dexin JIA and Fukang JIANG¹

National Taiwan University, Graduate Institute of Electro-Optical Engineering, 1 Roosevelt Road Sec. 4, Taipei, 106, Taiwan, R.O.C.
¹Umachines, Inc., 2400 N. Lincoln Avenue, Altadena, CA 91001, U.S.A.

(Received October 18, 2004; Accepted January 31, 2005)

In this paper, we describe the design principles of serpentine springs with high reliability for the micro-electro-mechanical systems (MEMS) optical switches with large mirror mass. The most often seen failure mode of the MEMS optical switches under reliability tests is the breaking of these springs, which provide the restoring force for the MEMS actuators. The breaking points are usually at the turning corner of the serpentine springs when the MEMS optical switches are under a high G shock test or a vibration test. In order to overcome the difficulties, we redesigned the corner shapes of the springs with careful consideration. We will discuss the theoretical analysis and simulation modeling for the corner shapes of serpentine springs. MEMS optical switches with redesigned serpentine springs are fabricated and tested to prove the proposed design. The results show that the MEMS optical switches with new serpentine springs can pass rigorous reliability tests.

Key words: MEMS, optical switches, serpentine springs, corner effects, failure modes, reliability

^*E-mail address: gdjsu@cc.ee.ntu.edu.tw