- 學位論文
金薄膜點火頭之起爆能量與升溫狀態模擬
Simulation of Activating Energy and Temperature Histogram of Thin-Film Igniters
摘要
電火工品的發展隨著微機電製程技術日趨成熟，已將傳統電阻絲加熱模式縮小為金屬薄膜熱點加熱之型態，配合相關軍需及民生工業之應用，舉凡火箭點燃、脫節推進及汽車安全氣囊啟動，皆能有效發揮其發火能量低、快速反應及電橋高溫起爆的優點，成功達到點火起爆之作用；也對點燃鈍感火藥與燃料推進的起爆劑提供一更安全可靠的點火機制。為符合軍需使用，低起爆能量、快速發火、縮短反應時間及抗電、抗磁干擾的規格測試，金屬薄膜點火電橋之研製試用，已成為相關製程技術擴展批量製作的典範。 本文依據先前相關研究結果，選用金作為蒸鍍薄膜電橋的材料，並針對點火頭柱塞頂面之不同幾何構形金薄膜電橋，引用電熱理論作為電橋點火時的能量轉換機制及模擬計算的基礎。本研究以數值方法探討電點火頭起爆能量與升溫狀態等點火特性之影響，模擬金薄膜電橋承受固定電壓的電容器瞬間放電時，電橋受電焦耳加熱與柱塞散熱等升溫歷程，由起爆藥劑的起爆溫度判定發火與否；同時模擬不同寬度電橋承受固定電流與時間的不發火狀況，根據這些發火的模擬結果評估及設計薄膜電橋尺寸。數值模擬結果顯示：本研究設計的三種電橋形狀－矩形、扇形及內圈加大矩形，在發火條件的模擬當中，無論是選用20V-20μF或300V-0.0022μF的供電方式，均可順利達成發火判定下所需之發火溫度，並通過基於環境安全而設定的不發火條件測試。八種橋寬設計皆能通過發火與不發火條件需求，其中以橋寬約0.3~0.4毫米的矩形電橋兼顧溫度適中及熱點區域集中的優點，為較佳設計。本文研究結果可提供未來點火頭薄膜電橋幾何構形研究的基礎。
並列摘要
With the progressive of MEMS technology, the evolution of electro- explosive devices has been miniaturized from the conventional heating of electric wire to hot-spot activating of metal thin-film. For the application of military and commodity industry, such as the ignition of rocket and thruster, and the actuation of automobile supplement restraint system (SRS), electro-explosive device has been utilized effectively and meet the demands for ignition due to its featured advantages of low activating energy, rapid response and high-temperature detonation. A reliable regime of ignition is therefore provided for the subsequent detonation of insensitive explosives and fuel propulsion. To meet the specification of arms, e.g., low activating energy, rapid ignition, quick response and the tests for anti-static-electric and anti-magnetic fields, the fabrication and utilization of thin-film bridge has provided a successive example of batch manufacturing techniques. Based on the experiences, gold (Au) was chosen as the deposition material of the thin-film bridge in this study. Various designs of Au thin-film bridges over-laid on the top of igniters were numerically investigated by solving the equations governing the electric-thermal conversion and heat transfer. With the efforts of numerical simulation, the effect on igniting characteristics was investigated from the perspective of activating energy and temperature histogram. Variation of the bridge width was taken as a variant for the simulation of ignition of a real Au thin-film igniter. The specific designs of Au-bridge geometry, i.e., rectangle, sector, and rectangle with enlarged inner ring, were investigated. With the two designated detonating conditions, which are the energy supply of 20V-20μF and 300V-0.0022μF, respectively, these 3 thin-film configurations could meet the criteria of successive initiation and non-detonation settling for the environmental safety consideration. This research presents the temperature histogram of the Au bridge under activation, which is governed by the electric-joule heating and the heat dissipation from the inner-plug as the igniting electric impulse discharged from a capacitor passing through the bridge. The criterion of the success of activation was determined if the rising temperature reaches the detonating temperature of the primer. The temperature of the bridge subjected to 0.1A-5min was also simulated. The simulation of 8 rectangular bridges with various bridge-widths showed their capability to meet the requirement of detonation and non-detonation. From the simulations, the bridge width of 0.3~0.4 mm would be considered as an optimal dimension for the rectangular thin-film igniter with the advantages of both suitable temperature distribution and concentrated hot-spot area. These simulation results allow the assessment and design of the bridge pattern, length, width, and thickness of the metal thin film.