Shock Impact Reliability and Failure Analysis of a Three-Axis MEMS Gyroscope

This paper presents the reliability assessment of a three-axis microelectromechanical systems (MEMS) gyroscope subjected to various shock loading conditions. The reliability tests include three different impact orientations and several acceleration levels of shock impact, ranging from 1500 to 15 000 g. The package failure and functional failure of the MEMS devices are studied separately. The failure analysis shows package failures of the MEMS device at a shock level above 8000 g and the functional failures of the device caused by stiction or fractures in the comb structure at a moderate shock level around 4000 g. To have a comprehensive understanding of the failure modes and predict the failure modes, dynamic finite element analyzes with direct integration are employed to investigate the nonlinear responses of the MEMS device under shock impact loadings. Internal collisions between the movable elements and the stationary parts are modeled by contact definitions. The simulation results, such as the calculated structural deformation and stress distributions, can be used to predict potential failure sites and offer explanations to the observed package failures and comb structure fractures. Furthermore, the locations of possible stiction inside the MEMS structure are also predicted by the simulation results.