微型離心式加速度開關之設計與研製

Abstract

本論文以數值計算軟體ANSYS/LS-DYNA配合微機電系統(MEMS)製程，設計並研製微型離心式加速度開關(或稱G-開關)。當加速度開關承受達到定限值加速度與旋轉角速度時，其內部的觸發開關將由斷路變成通路，輸出致動的訊號，開啟外接電路，使裝置得以進行後續程序。 加速度開關受環境外加之加速度達到定限值時，使得內部之質量塊因慣性力而產生相對位移，推動觸發機構，導通電路，達成開關之目的。為檢視加速度開關作動歷程，本研究首先設計合適的加速度感測元件及鎖定機構，模擬離心加速度開關受衝擊時之動態響應。在離心向時，當轉速在1000rpm以下安全不作動；轉速達到2000rpm以上時，則進入鎖定的致動狀態。有別於一般的加速度開關，離心加速度開關同時受主軸向及離心向兩加速度場影響，因此額外設定主軸向受1000G衝擊，並探討其影響，最後觀察加速度開關之動態響應及應力分布情況。根據衝擊模擬之結果，決定加速度開關的幾何構型，電訊號則以導體接觸的方式輸出。 本研究接著以微機電系統製程研製所設計之加速度開關，基材使用內夾氧化層的SOI (silicon on insulator)矽晶圓，經半導體製程研製出所設計的加速度開關，並利用離心機台裝置給予定限值的加速度，實驗結果顯示加速度開關的卡榫成功鎖定，且在作動過程中，材料均在彈性範圍內，無破壞現象。以1V的電源串聯電阻對釋放機構加熱，在極短時間內成功解除鎖定狀態，達到加速度開關可重複使用之目的。

This thesis presents design and fabrication of a micro centrifugal G-switch by ANSYS/LS-DYNA and micro-electrical-mechanical system processing techniques. As the acceleration switch, also called the G-switch, subjected to sufficient levels of axial and centrifugal accelerations, the switch will turn from off to on, delivering signals to the connect circuits which can initiate subsequent processes. As the G-switch receives acceleration exceeding threshold from surroundings, the proof-mass in the G-switch experiences an inertial force which moves the contact components in touch to trigger output signals. To appropriately investigate the micro centrifugal G-switch, this thesis first designed suitable accelerators and latching mechanism, then simulated numerically the dynamic response of the G-switch subjected to applied impact conditions. As the projectile rotated with a centrifugal acceleration below 1,000 rpm, the installed G-switch was not turned on, staying in a safety mode. The device would be latched up as the spin rate above 2,000 rpm. An additionally axial acceleration impact of 1000G was also applied to the centrifugal G-switch to emulate the launching situation. Numerical results of dynamic response and stress distribution were revealed to evaluate the performances of accelerometers. A novel design of latching mechanism with releasing components was figured out. Based on the simulated numerical results, this thesis fabricated the micro centrifugal G-switch chips on a silicon-on-insulator (SOI) wafer via MEMS processing. Upon finishing the manufacturing processes, G-switch chips were tested by a centrifugal machine to investigate the performances of the fabricated devices. Test results show that the designed G-switch functioned properly as the acceleration reached the threshold, and all components of the G-switch were in the elastic region of the silicon without destruction. Heating the release mechanisms by applying 1 voltage DC source regulated with series resistors, this latched state was successfully discharged in a short time, fulfilling the purpose of reusing the G-switch.