Thermo-mechanical stress investigation of integrated SAW strain sensors

This paper presents investigations of thermo-mechanical stress generated due to the integration process of Surface Acoustic Wave (SAW) strain sensors. A 3D finite element (FE) model, based on visco-elastic material measurements, is developed for thermo-mechanical stress computation. The simulation results are compared with experiments. Therefore, SAW strain sensors were mounted, the sensor response and the sensor deformation measured. The deviation between the simulated and measured sensor chip deflection is ≤ 14.4% for the full measurement range. Simulated thermo-mechanical stresses were used for the frequency shift computation of the SAW sensor device. The calculated frequency shift and the performed deformation measurement verified the correctness of the FE model.