基于两级应力隔离的MEMS加速度计封装设计

封装应力是影响MEMS加速度计性能尤其是温度特性的关键因素之一.为降低封装应力,提出了一种两级应力隔离的低应力封装设计,包含芯片级应力隔离和封装级应力缓冲.采用有限元仿真模拟了四种封装设计和四种粘片方式.仿真结果表明,芯片级应力隔离比封装级应力缓冲效果更好,采用两级应力隔离可以将敏感电容的温度特性改善8倍,且四点胶粘片...

Package Design of MEMS Accelerometer Based on Two-stage Stress Isolation

Package stress is one of the key factors that affect the performance of MEMS accelerometer,especially the temperature characteristic.In order to reduce package stress,a low stress package design with two-stage stress isolation is proposed,which contains chip-level stress isolation and package-level stress buffer.Four package designs and four bonding methods are simulated by finite element analysis.Simulation results show that the chip-level stress isolation is better than the package-level stress buffer.Using two-stage stress isolation can improve the sensing capacitor s temperature characteristic by 8 times,and the die attach with four dots is the best.Furthermore,process and parameters of the four-dot dispensing are optimized by experiment.Experimental results show that the mean bias temperature coefficient of 95 accelerometers designed with low stress package decreases from 1450×10^-6g/℃to 243×10^-6g/℃,and the mean bias stability and bias repeatability are 92×10^-6g and 45×10^-6g,respectively.