MEMS高量程加速度传感器封装技术仿真研究

Packaging Technology Simulation of MEMS High Measure Range Accelerometer

针对现有MEMS高量程加速度传感器芯片结构设计了一种不锈钢管壳封装结构,通过有限元软件分析研究了灌封对高量程加速度传感器封装性能的影响.仿真结果表明,管壳结构在200 000 g的冲击载荷下,其所受到的最大应力为260.538 MPa,小于不锈钢的抗拉强度785 MPa,可以承受高达200 000 g的冲击载荷.灌封可以提高封装模型的固有频率,同时可减小MEMS敏感结构受到的应力;灌封胶的弹性模量会对传感器封装结构模型的性能产生较大影响,其固有频率会随着灌封胶弹性模量的增大而增大;而在相同载荷作用下,封装模型受到的应力会随之减小.但是灌封胶弹性模量太小,封装结构模型的模态频率反而会小于未灌封时结构模型频率,使封装结构在冲击环境下易发生共振现象.

A practical packaging structure was designed for the designed MEMS high measure range accelerometer, and encapsulation performance was simulated when it used potting. By the result of simulation, the packaging structure can meet the requirements of sensor, which can test the available signal under 200 000 g impact loads. From the results of modal and static simulation, potting can not only improve the natural frequency of the package model, but also can reduce the stress when shock load effected on the model. Elastic moduli of the potting materials have the great influence on the package performance, but the density has little effect on it. The simulation results also show that the modal frequency of the package model increases with modulus increases, while the stress reduce when the same load on the package model. However, the modal frequency is much smaller than the packaging structure without potting when the elastic modulus was too small, which may bring a distortion of the sensor output signal.