基于柔性止动的MEMS惯性开关冲击可靠性强化

Shock reliability enhancement by flexible stop for MEMS inertial switch

为了提高MEMS惯性开关的冲击可靠性,提出了一种柔性止动结构。首先,利用连续接触力理论建立了止动碰撞模型,通过Simulink对模型进行仿真,研究开关在不同止动形式下的响应特性。接着,从空间占用和应力集中的角度对悬臂梁和平面微弹簧两种止动形式进行讨论,设计止动结构。最后,利用UV-LIGA工艺制作开关样机,通过落锤冲击系统对样机进行测试。碰撞接触力对于冲击可靠性至关重要,Simulink仿真结果表明柔性止动结构能够极大的延长碰撞接触时间,从而降低接触力。同时,采用柔性止动还改善了碰撞后的弹跳现象,提高闭锁稳定性。冲击试验表明,开关累积失效分布函数符合韦布尔分布,标度参数(参考加速度)α=29 600、形状参数β=8.2。相比无柔性止动的MEMS开关,提出的柔性止动明显改善了开关的抗冲击性能。对柔性止动的建模、仿真与试验为MEMS惯性开关的抗冲击设计提供了有益参考。

To improve the shock reliability of the MEMS inertial switch,a flexible stop structure was proposed.Firstly,the stop collision model was established using the theory of continuous contact force,and the response characteristics of the switch in different stop modes were researched conducting simulation on the model through Simulink.Then,from the perspectives of space-efficient and the stress concentration,the cantilever type and plane micro-spring type stops were discussed and the stop structure was designed.Finally,the switch prototypes were fabricated using the UV-LIGA technology,and the prototypes were tested by the drop hammer shock system.Collision contact force was critical for shock reliability,Simulink simulation result shows that the flexible stop structure can greatly prolong the collision contact time,thus reducing the contact force.At the same time,it also improves the contact bounce phenomenon using flexible stop after collision and the stability of latching.The shock test shows that the cumulative failure distribution function （CDF） of the switch accords with Weibull distribution,with scale parameter （reference acceleration） a=29 600,shape parameter β=8.2.Compared with the MEMS switch without flexible stop,the proposed flexible stop improves the shock resistance of the switch significantly.Modeling,simulation and test of flexible stop provide beneficial reference resources for anti-shock design of MEMS inertial switch.