ANSYS 谐振梁加速度计封装应力研究
毕业论文关键词 谐振梁加速度计 封装应力 粘合剂 有限元分析
Title Study on the Package Stresses of the Silicon-resonant Accelerometer
Abstract The sensitive structure of silicon-resonant accelerometer has high sensitivity to stresses, the stresses generated during the process of package has a great influence on the performance of silicon-resonant accelerometer. In this paper, the theory, simulation and experimental analysis on package stress were carried out. Firstly, the mechanism of stresses and the adverse effects of thermal package stresses on the performance of accelerometer have been theoretically analyzed. Then, based on ANSYS Workbench simulation platform, The impact of package stresses that coefficient thermal expansion, Young's modulus and the thickness of the adhesive caused were studied, And the results show that the lower Young's modulus, a matching coefficient thermal expansion and the thicker layer of adhesive will cause low stresses. The influence of the adhesive forms on the stresses was analyzed. And a low-stress package scheme was studied that a silicon gasket between the sensor die and ceramic basement can effectively reduce the package stresses. Finally, the package experiments were carried out, and the package stresses were valued with the resonator frequency changed before and after the packaging. This paper lays the foundation of low-stress packaging technology for the silicon-resonant accelerometer.
Keywords silicon-resonant accelerometer package stresses adhesive Finite-element analysis
目次
1引言1
1.1MEMS封装概述1
1.3本课题研究的目的与意义3
1.4本文研究内容3
2谐振梁加速度计理论基础5
2.1谐振梁加速度计工作原理及制造工艺5
2.2封装结构热机械耦合效应的理论建模9
2.3有限元理论11
2.4本章小结12
3谐振梁加速度计热应力仿真13
3.1ANSYSworkbench简介13
3.2仿真步骤13
3.3仿真结果16
3.4本章小结22
4.谐振梁加速度计封装实验23
结论25
致谢26
参考文献27
1 引言 微机电系统（Micro-electro-mechanical Systems），简称 MEMS，是在微电子技术（半导体制造技术）基础上发展起来的集微执行器、微传感器、微电源、微能源、微机械结构、高性能电子集成器件、信号处理与控制电路、通信、接口等于一体的微型器件，并可以与光电子、微电子、射频（RF）、力学和热学器件集成为先进的微系统[1]。 MEMS 加速度计广泛应用于军事、民用和空间技术等领域，是微传感器的热点研究对象。硅微谐振梁加速度计(silicon-resonant accelerometer)，简称 SRA，是一种基于双端固定音叉（DETF）结构的用于将加速度变化转化为谐振频率变化的微惯性器件，具有易加工、体积小、质量轻、低功耗、低成本、稳定性好等特点，而且输出信号是便于测量控制的频率信号，受外界干扰影响小，较易达到高精度测量的要求[2]。SRA 是MEMS 加速度计的一个关键发展方向，主要应用于潜艇导航、导弹制导等要求高精度和高可靠性的场合，目前国内外很多高校和研究机构正在对此展开研究。 在所有要求低成本和小尺寸的系统中，集成的各种材料和元器件越来越多，结构越来越复杂，MEMS 器件失效问题也越来越严重。热应力分为加工应力和封装应力,封装过程中由于各种材料的热失配产生的封装应力，是影响器件性能的主要原因，因此 MEMS 封装通常是整个加工过程中考虑的重点。