Research On The Structural Simulation And Packaging Technology Of The Three-axis Accelerometer Based On The Mechanisms Of Resonance-force Balance Capacitance

The there-axis accelerometer have been widely adopted in many areas of car navigation,aerospace and other fields due to their small size,light weight,low power consumption,low-cost integration and mass production.As micro-fabrication technology marches forward and the growing demand in fields such as civil and defense,the research of there-axis accelerometers has gradually become an important development direction of there-axis accelerometers.Aiming at the fact that the detection mechanism of the current micro three-axis accelerometer is lack diversity,the research team proposes a bulk micro machined three-axis accelerometer with a single-mass based on the mechanism of composite detection of resonance-force balance capacitance.Resonance detection system formed by a proof mass,crab leg support beams and resonant beams detects in-plane acceleration.The differential capacitance system formed by the upper cover plate,the proof mass and the lower cover plate detects the out-of-plane acceleration.The center of the proof mass is located in the neutral plane of supporting beams,reducing the inversion of the proof mass due to in-plane acceleration,so that the accelerometer has a smaller cross-axis sensitivity.In this paper,the working principle and sensitivity of the resonant-force balance capacitive there-axis accelerometer are analyzed theoretically.Ansys Workbench15.0 is used to simulate the performance of the accelerometer,including vibration mode,sensitivity,cross-axis sensitivity and measurement range.By simulating the influence of the thickness of the resonant beam on the sensitivity and the cross-axis sensitivity of the there-axis accelerometer,the thickness of resonant beams is optimally designed,so that the sensitivity,the cross-axis sensitivity and the measurement range are obtained.The accelerometer packaging process has been studied.The main chip,upper cover and lower cover are bonded together by the Au-Si eutectic bonding technique.The bonded chip is encapsulated with a ceramic shell by Au-Sn eutectic bonding technology.Preliminary test results show that the three-axis accelerometers have sensitivities of 23.39Hz/g,12.11Hz/g,and 19.92mV/g(1.867×10^-14F/g)in the three directions of X,Y and Z,respectively.The cross axis sensitivity of the X axis and Y axis is 2.52%and 2.12%,respectively.