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, giventhat certain setting times after temperature changes are maintained. Signal errors arise when temperature changesinduce time-dependent viscoelastic relaxation in the adhesive which cannot be compensated by calibration. High precisionapplications which demand absolute signal accuracies below 30Pa on chips well below 1mm scales, while the requirementof factory calibration before soldering demands highly temperature stable adhesives. An experimentally verified, finiteelement-based simulation model is used to investigate static and hysteretic stresses in the sensor, demonstrating alarge potential for the reduction of temperature-dependent stresses affecting signal, including hysteretic stresses. This isachieved by determination of adhesive geometries that allow stress compensation, balancing opposing adverse stressesto cancel out. Using this approach, it is demonstrated that the signal hysteresis can be significantly reduced, whilemaintaining critical characteristics such as sensitivity and size.

本研究致力于探讨粘合封装微机电系统压力传感器的时间依赖性滞后效应。此类传感器通常在特定的温度和压力范围内进行校准，并在温度变化后保持一定设置时间，从而提供精确的压力测量。然而，当温度变化导致粘合材料发生无法通过校准补偿的时间依赖性粘弹性松弛时，会引发信号误差。在要求芯片尺寸低于1毫米且信号绝对精度低于30帕斯卡的高精度应用中，焊接前的工厂校准对粘合材料的高温稳定性提出了严格要求。通过使用实验验证的基于有限元分析的仿真模型，本研究对传感器的静态和滞后应力进行了研究，展示了降低影响信号的温度依赖性应力的巨大潜力，包括滞后应力。这通过确定能够实现应力补偿的粘合几何形状，平衡相反的不利应力以相互抵消来实现。采用该方法，显著降低了信号滞后，同时保持了诸如灵敏度尺寸等关键特性。