低g值微惯性开关单向敏感性设计与分析

Design and analysis on unidirectional sensitivity of low-g micro inertial switch

选用典型的"弹簧-质量"系统,基于平面矩形螺旋梁结构,研制了一种具有良好单向敏感性的低g值微惯性开关。采用ANSYS有限元软件,对惯性开关的单向敏感性进行了静力学仿真分析。分析结果表明,横向加速度对惯性开关闭合阈值的影响较小。采用MEMS体硅加工工艺和圆片级封装技术,包括KOH腐蚀、ICP刻蚀和喷涂工艺等关键工艺技术,完成了微惯性开关的制备。经离心试验测试,微惯性开关的闭合阈值约为12.26g,具有约±0.2g的闭合精度。当横向惯性加速度小于15g时,对其闭合阈值的影响小于0.5g。测试结果表明,微惯性开关具有较好的单向敏感性,多次测试重复性好,具有体积小、结构简单、加工容易实现、环境适应性好等特点。

This paper presents a low-g micro inertial switch with good unidirectional sensitivity based on the planar rectangular helical spring by adopting a classical spring-mass system.The unidirectional sensitivity of the inertial switch is analyzed utilizing the ANSYS finite element method.The simulation results demonstrate that the lateral acceleration has small effect on the threshold acceleration.The micro inertial switch is fabricated using the MEMS bulk micromachining process and packaged in wafer level,including the crucial technology of KOH etching,ICP etching and spray coating.Laboratory centrifuge test is carried out to character the fabricated inertial switch.The threshold value is about 12.26g,its closing precision is about ±0.2g,and the variety of the threshold acceleration is less than 0.5g when the lateral acceleration is less than 15g.It is shown that the inertial switch has good unidirectional sensitivity and the closing precision in multiple tests is good.The advantages of the switch are small size,simple structure,easy fabrication and good environmental adaptability.