Reliability assessment of a MEMS microphone under shock impact loading

In this paper the shock impact reliability of a MEMS microphone is studied through experiments and finite element simulations. The maximum acceleration tolerance of the device is studied and the effect of shock impact orientation is also investigated. Finite element method is employed to determine the potential failure locations of the MEMS structure. Several challenges of the modeling process, such as the large differences in dimension, the complexity of the structures, and the material properties of the materials in the MEMS devices, are investigated and solutions are presented. The shock impact response simulations are used to determine the mechanical response of the MEMS structures. The contact between the backplate and diaphragm is also included in the simulation investigations. The deformations of these membranes are related to the vibration modes excited by the shock impact and the stress concentration regions are regarded as potential failure sites. The predicted failure sites are in good agreement with the experimental findings. The modeling results are used to explain the failure mechanisms related to the observed failure modes. Furthermore, it is found that both the acceleration limits and the fatigue life characterization are dependent strongly on the impact orientation. This work gives insights into the reliability of MEMS microphones under shock impact loading. Different failure modes are distinguished through shock impact tests with different acceleration levels. The simulation approach deepens the understanding of deformation and stress states in the MEMS structures.