三梁-质量块敏感结构高性能压阻式碰撞加速度计

研究了一种主要应用于碰撞测试领域的硅微机械高性能压阻式加速度计,量程范围为2 000 gn.为满足技术性能要求,加速度计采用一种三梁-质量块结合梳齿阻尼器的新颖结构,从而可以同时具有高灵敏度及高动态特性(包括高谐振频率及精确阻尼控制).这种加速度计采用n型(100)普通硅片制作,主要工艺过程包括双面ICP深刻蚀和压阻集成工艺.振动台测试结果表明,加速度计的灵敏度为0.11 mV/gn/5 V,谐振频率为31 kHz,灵敏度±5%变化下平坦带宽大于5 kHz.采用落杆测试法测试了加速度计的冲击响应及0～2 000 gn满量程范围内的非线性度.封装后的加速度计承受15 000 gn的冲击测试后没有受到损坏.

Three-Beam-Seismic-Mass Structure Piezoresistive Accelerometer for High Performance Crash Test

A silicon micromachined high performance piezoresistive accelerometer is developed for crash assessment. The full measure range is 2000g. For meeting the technical requirements, a novel sensor scheme is used that features both high sensitivity and high dynamic characteristics (including high resonant frequency and precise damping ratio). A three-beam-seismic-mass structure is proposed with the combination of a comb damper. Standard n type (100) silicon wafers are used here for micro-fabrication of the sensors. Double-sided deep RIE is processed for the micromechanical structure that is combined with the piezoresistive integration process. Vibration table test results show that the normalized sensitivity of the accelerometer is measured as 0.11mV/g/5V. The resonance frequency is 31kHz, with the band of ±5% variation in sensitivity wider than 5kHz. The shock response and the nonlinearity of the accelerometer are characterized using dropping bar test method. 15000g shocking test has been implemented to the packaged device, resulting in safe survival.