Drop impact reliability of MEMS inertial sensors with membrane suspensions for mobile phones

MEMS accelerometers and gyroscopes enable new functions for portable electronics such as smartphones and tablet computers. Membrane suspensions are suitable for the inertial sensors using piezoelectric or piezoresistive effect, but they are susceptible to be damaged by drop impact. In this paper, system-level drop impact reliability was investigated for MEMS inertial sensors with membrane suspensions. Drop tests of the sensor modules mounted on mobile phone mockups were performed to observe effects of package parameters and impact orientation. After repeated drop tests, almost all membranes were broken while the failures could not be expected from component-level simulation. Therefore, a failure mechanism due to membrane buckling was suggested from system-level simulation and correlated with the drop test results. Based on the failure mechanism, new stopper design was applied and the drop impact failure was completely eliminated.