Mariani Stefano, Ghisi Aldo, Corigliano Alberto, Zerbini Sarah
Dipartimento di Ingegneria Strutturale, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano (Italy).
MEMS Product Division, STMicroelectronics, Via Tolomeo 1, 20010 Cornaredo (Italy).
Sensors (Basel). 2007 Sep 7;7(9):1817-1833. doi: 10.3390/s7081817.
The effect of accidental drops on MEMS sensors are examined within the frame-work of a multi-scale finite element approach. With specific reference to a polysilicon MEMSaccelerometer supported by a naked die, the analysis is decoupled into macro-scale (at dielength-scale) and meso-scale (at MEMS length-scale) simulations, accounting for the verysmall inertial contribution of the sensor to the overall dynamics of the device. Macro-scaleanalyses are adopted to get insights into the link between shock waves caused by the impactagainst a target surface and propagating inside the die, and the displacement/acceleration his-tories at the MEMS anchor points. Meso-scale analyses are adopted to detect the most stresseddetails of the sensor and to assess whether the impact can lead to possible localized failures.Numerical results show that the acceleration at sensor anchors cannot be considered an ob-jective indicator for drop severity. Instead, accurate analyses at sensor level are necessary toestablish how MEMS can fail because of drops.
在多尺度有限元方法的框架内，研究了意外掉落对微机电系统（MEMS）传感器的影响。具体针对由裸芯片支撑的多晶硅MEMS加速度计，分析被解耦为宏观尺度（在芯片长度尺度）和细观尺度（在MEMS长度尺度）的模拟，同时考虑了传感器对器件整体动力学的极小惯性贡献。采用宏观尺度分析来深入了解撞击目标表面并在芯片内部传播的冲击波与MEMS锚点处的位移/加速度历史之间的联系。采用细观尺度分析来检测传感器中应力最大的细节，并评估撞击是否会导致可能的局部故障。数值结果表明，传感器锚点处的加速度不能被视为掉落严重程度的客观指标。相反，有必要在传感器层面进行精确分析，以确定MEMS因掉落而失效的方式。
