Font Size: 

A study of the mechanical response of MEMS sensors subject to accidental drops is dealt with in the present paper. Experimental and theoretical investigations aiming at understanding shock- and dropinduced failures in MEMS sensors were pursued in the past. However, a detailed numerical description of the failure mechanisms in polysilicon devices, and the micro-mechanical links with the stress waves caused by the impact still look incomplete.
In this work, we perform dynamic analyses of MEMS accelerometers supported by a naked die, subject to shock loading due to drops. Due to the s mall ratio between sensor and die inertial properties, a decoupled three-scale approach is adopted: at the macro-scale (die) it is supposed that the falling device strikes a flat, rigid surface; at the meso-scale (sensor) acceleration records resulting from macro-scale analyses are adopted as input loading to detect critical sensor details; at the microscale (silicon grain) crack propagation at grain boundaries and within grains, possibly leading to MEMS failure, is simulated through a cohesive approach.