压阻式加速度传感器封装应力隔离结构分析

测试特性的温度漂移是压阻式加速度传感器研发中的固有问题，与器件制造的多个环节相关，是多因素共同作用的结果。封装应力的隔离是消减传感器特性温度漂移的重要手段之一。为详细分析封装应力隔离结构的引入效果及其对传感器测试特性的影响，以传统双桥式敏感结构为基础，采用有限元方法分析了封装应力隔离结构对传感器附加干扰载荷抵抗力的提升作用，并分析了从其引入后对传感器敏感应力和结构固有频率的影响。分析结果表明，引入封装应力隔离结构可有效降低外部干扰应力对传感器敏感结构的影响，同时也会改变结构固有频率在内的传感器测试特性。因而，当封装应力隔离结构应用于高频型加速度传感器时，需通过优化结构质量分布、采用横向敏感结构等方法对提升结构自身固有频率及实现敏感方向与隔离变形方向解耦等问题进行进一步优化。

Investigation on Mechanical Isolation of Packaging Stress in Piezoresistive Accelerometer

Temperature drift of sensor measuring characteristics is an inherent problem in the research of piezoresistive accelerometer, which can be attributed to various issues in the processes of device fabrication. It is the result of many factors acting together. Among them, the packaging stress contributes a lot in the thermal instability and its isolation is a feasible solution for the performance enhancement. In order to analyze the introduction effect of packaging stress isolation structure on the sensor measuring characteristics in detail, based on the traditional double-bridge sensitive structure, the finite element method is used to analyze the effect enhancement of packaging stress isolation structure on the resistance of sensor to additional interference load, and the influences of sensor sensitive stress and structure natural frequency after the introduction of packaging stress isolation structure is analyzed. The analysis results show that the introduction of packaging stress isolation structure can effectively reduce the influence of external interference stress on the sensor sensitive structure, and also change the sensor measuring characteristics including structure natural frequency. Therefore, when the packaging stress isolation structure is applied to high frequency accelerometer, it is necessary to further optimize promotion of the isolation structure natural frequency and realization of decoupling the sensitive direction and isolation deformation direction by optimizing the mass distribution of the structure and adopting transverse sensitive structure.