Shock Destructive Reliability Analysis of Electromagnetic MEMS Micromirror for Automotive LiDAR

Abstract

Light Detection and Ranging (LiDAR) devices are preferred sensors in the field of automatic and intelligent driving. LiDAR based on Micro-Electro-Mechanical Systems (MEMS) micromirrors has gained vital attention owing to the advantages of MEMS devices. In a harsh environment, the shock reliability of micromirrors has significantly constrained automotive applications, but such studies are rarely reported. In this work, the shock destructive reliability of electromagnetic MEMS micromirror in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$z$ </tex-math></inline-formula> -direction is investigated to accelerate the commercialization of MEMS-LiDAR. The drop fall tests cover from 100 to 800 g in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$z$ </tex-math></inline-formula> -direction, and the fracture emerges at the shock level of around 700 g. To comprehensively explore the factors of shock destructive reliability, finite element and dynamic models are completed. Finite element analysis is employed to investigate the stress distribution under shock loads, and the fracture is located at the position of maximum stress. The dynamic response and peak stress with shock pulses are explored numerically by the established dynamic model. The calculated results demonstrate that the response reaches a peak when the frequency of shock is the same as the natural frequency of micromirror. The results of peak stress with varied shock levels can be utilized to quickly predict the shock resistance. This work provides a deep insight into the optimization for the design of MEMS micromirror, which may promote the applications of MEMS-based LiDAR in autonomous driving. [2021-0200]