Top-down, multi-scale numerical simulation of MEMS microphones under guided free fall tests

Failures on MEMS microphones placed on dummy smartphone are observed during a guided free fall test. The instants before and after the first impact are registered with a high-speed camera and the displacement/velocity signals are used as input for three-dimensional finite element analyses at different scales to obtain insights at local level to judge whether possible ruptures arise. The numerical procedure follows a multi-scale, top-down approach and it can adopt both fluid-structure interaction and purely mechanical analyses. Finally, two loadings are transferred at the micro-scale to the thin silicon membrane representing the microphone: it is found that, in some drop cases, failures depend from the combination of the fluid-induced (air over-pressure) and of the solidinduced input (relative displacements at the anchors), and not from a single domain loading condition.

Automated summary

During guided free fall tests on MEMS microphones placed on a mock smartphone, failures were observed. High-speed camera recordings of the moments before and after the first impact were used as input for three-dimensional finite element analyses at various scales to understand potential ruptures at a local level. The analysis showed that failures in some cases were due to a combination of fluid-induced air over-pressure and solid-induced displacements at the anchors, rather than a single loading condition.