基于平面矩形螺旋梁的低g值微惯性开关的研制

Development of a Low-g Micro Inertial Switch Based on Planar Rectangular Helical Spring

以弹性材料单晶硅为结构材料,研制了一种基于平面矩形螺旋梁的低g值(1 g～30 g)微惯性开关.根据材料力学中的卡氏定理和线弹性理论,推导得到了惯性开关闭合阈值的计算公式,其计数结果与ANSYS有限元分析结果的相对误差小于3%.为提高低g值微惯性开关的环境适应能力,提出双触点和低频弹簧-质量的结构设计方案.为提高结构尺寸的加工精度,提出基于双埋层SOI的低g值微惯性开关加工工艺方案.采用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,划片后芯片尺寸为7mm×7mm×1.3mm.经离心试验测试,微惯性开关的闭合阈值为6.45 g,具有优于±0.5 g的闭合精度.通过随机振动和高温等环境试验后,2只微惯性开关样品闭合阈值的变化量小于0.5 g,表明微惯性开关具有较好的环境适应能力和机械性能.

A low-g （1 g-30 g） micro inertial switch based on planar rectangular helical spring was developed. Single crystal silicon with perfect mechanical property was used as the structure material. The onstate threshold fomula of the inertial switch was derived with the Castigliano＇s theorem and the linear elasticity theory of material mechanics. The relative error is less than 3 % between the theoretic and the AN- SYS simulation results. Designs of double contact points and low natural frequency of the mass-spring structure were proposed to improve the environment adaptability of the micro inertial switch. The fabrication process utilizing SOI wafer with double buried layers was carried out to improve the precision of structure parameters. The micro inertial switch was fabricated using crucial technology including KOH etching, ICP etching and spray coating. The bulk of chip is about 7 mm× 7 mm× 1.3 mm in size. The laboratory centrifuge tests were performed on the fabricated inertial switch to measure the on-state threshold. The test results show that the threshold value is about 6.45 g with a closed precision of 0.5 g. Amount of onstate threshold transfer caused by environment tests including random vibration test and high temperature test is less than 0.5 g, which shows that the developed inertial switch has better environment adaptability and mechanical property.