Numerical optimization of adhesive mounted MEMS pressure sensors

Our research addresses time-dependent hysteresis effects in adhesive packaged MEMS pressure sensors.
Typically calibrated inside a certain temperature and pressure range, they provide precise pressure measurements, given
that certain setting times after temperature changes are maintained. Signal errors arise when temperature changes
induce time-dependent viscoelastic relaxation in the adhesive which cannot be compensated by calibration. High precision
applications which demand absolute signal accuracies below 30Pa on chips well below 1mm scales, while the requirement
of factory calibration before soldering demands highly temperature stable adhesives. An experimentally verified, finite
element-based simulation model is used to investigate static and hysteretic stresses in the sensor, demonstrating a
large potential for the reduction of temperature-dependent stresses affecting signal, including hysteretic stresses. This is
achieved by determination of adhesive geometries that allow stress compensation, balancing opposing adverse stresses
to cancel out. Using this approach, it is demonstrated that the signal hysteresis can be significantly reduced, while
maintaining critical characteristics such as sensitivity and size.