Research On The Key Technologies Of Low-g MEMS Acceleration Switch

Acceleration switch is a typical inertial device.Due to the advantages of miniaturization,low or even no power consumption,low cost,and high reliability,MEMS(micro-electro-mechanical system)technology-based acceleration switches have great potential in military equipment,automotive industry,aerospace industry,environmental monitoring,and intelligent terminal,etc.Threshold accuracy and contact time are the key performance parameters of the MEMS inertial switch,which cannot satisfy the application requirements.As a result,it will be of great significance to do the research on the key theories and technologies of the MEMS inertial switch to improve the threshold accuracy and contact time.In this paper,based on the analysis of the research status of the MEMS inertial switch,a novel acceleration micro-switch based on protrusive electrode and enhanced squeeze-film damping effect was proposed to meet the application requirements of the ammunition security system,and a dynamic model of the proposed MEMS inertial switch was established.An analysis method of the shock response spectrum in consideration of air damping effect was put forward to analyze the performance parameters of the switch and the corresponding impact factors.The structure parameters of the switch were optimized to meet the index requirements,which were established based on the application requirements of the ammunition security system.The related key processing technologies were investigated,and subsequently the designed switch was fabricated.The test results of the fabricated switch were as follows: the threshold acceleration was 14.2~16.1g,the threshold accuracy was ±1g,the response time and contact time was 0.69 ms and 40?s,respectively,the shock resistance ability was better than 1000 g,the contact resistance was 10~15?.The main work of this paper is listed as follows:(1)The research status and major issues of the MEMS inertial switch were studied to determine the research scheme of this paper.(2)A novel acceleration micro-switch based on protrusive electrode and enhanced squeeze-film damping effect was proposed to meet the application requirements of the ammunition security system such as miniaturization,low g(gravity),low cost,high threshold accuracy,and high reliability.A theoretical model of the proposed switch was established,and an analysis method of the shock response spectrum in consideration of air damping effect was put forward,and hence some structural optimization method of the switch were proposed.(3)The index requirements of the switch were established based on the analysis of the application environment characteristics and requirements of the ammunition security system.Based on the theoretical model and the analysis results of the shock response spectrum,the structure parameters of the designed switch were optimized by the method of combining the numerical simulation and finite element simulation.As a result,the performance parameters of the switch such as threshold accuracy,contact time,and shock resistance ability were improved.(4)The key processing technologies of the switch such as ICP(inductively coupled plasma)dry etching and anodic bonding were investigated.The relevant process parameters were optimized in order to avoid the fracture of the serpentine springs during the device release and the blackening of the fixed electrode during the bonding process.The entire process flow of the switch was designed,and consequently the switch was fabricated.(5)The test method of the MEMS inertial switch was studied,and the test setup of shaking system was built,and the main performance parameters of the switch were tested and analyzed.The test results show that the threshold acceleration was 14.2~16.1g,the threshold accuracy was ±1g,the response time and contact time was 0.69 ms and 40?s,respectively,the shock resistance ability was better than 1000 g,the contact resistance was 10~15?.The test results show good agreement with the simulation results,and the threshold accuracy and contact time have reached the advanced level both at home and abroad.