微電化學放電加工法應用於硼矽玻璃的精微加工技術之研究; Microstructuring of Borosilicate Glass by Using Micro Electrochemical Discharge Machining

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題名:	微電化學放電加工法應用於硼矽玻璃的精微加工技術之研究;Microstructuring of Borosilicate Glass by Using Micro Electrochemical Discharge Machining
作者:	鄭志平;Chih-Ping Cheng
貢獻者:	機械工程研究所
關鍵詞:	電化學放電加工;硼矽玻璃;三維微細加工;補償式脈衝電壓;Borosilicate Glass;3D-microstructuring;Offset Pulse Voltage;ECDM;Electrochemical Discharge Machining
日期:	2008-04-28
上傳時間:	2009-09-21 11:52:52 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	硼矽玻璃(Borosilicate Glass、Pyrex glass)，由於具陽極接合、透光性及耐腐蝕等特性，所以有被大量使用於微機電系統或其它先進製程中的趨勢。但由於玻璃本身所具有的硬脆特性，因此很難實現高精度、高效率、高可靠性的加工，特別是在微型元件的製造上。近年來電化學放電加工已被證實為極有潛力應用玻璃材料的微加工製程上，然而實際製程的運用上，其加工精度、加工效率及重現性控制才是ECDM製程實用化之關鍵門檻。然而與製程精度及加工效率有直接關係的是放電特性，其影響的主要關鍵因子為絕緣氣泡膜的幾何外形與尺寸、及其結構穩定性。因此本研究使用不同的加工參數探討其對於電於電化學放電特性的影響，並進一步從中尋求改善策略。在運用於微孔加工上，實驗中利用扁平電極來減少電極側壁放電所造成的錐孔現象;並且採用脈衝電壓來減少放電能量的熱影響區以減少過切。結果顯示結合扁平電極與脈衝電壓對於微孔精度的改善上有顯著的效果，微孔的錐度可縮減3度。另外在微型元件的加工上，結果顯示在使用脈衝電壓與提高電極轉速的狀況下，結合層狀加工的方法，可以獲得高精度與高深寬比之微結構，並藉此證實了電化學放電加工運用於三維微細加工的可行性。雖然使用脈衝電壓來調控單位時間內放電的能量，對於改進加工精度是有利的，但是卻很難獲得符合期待的加工效率。主要是因為在脈衝休止時間內並無電壓的供應，電解氣泡並非持續的產生，這將使得氣膜結構狀況變為更不可預期，使得後續所引發的放電現象變的不穩定，造成加工效率和重現性不佳。對此研究中嘗試著開發設計一新的脈衝供給型態，稱之為補償式脈衝電壓，此乃是在脈衝休止時間內仍提供一恆定且微量的電壓以確保電解氣泡持續的產生，藉此改善脈衝周期內氣膜結構的完整性以提昇放電能量釋放的穩定性。結果顯示利用補償式脈衝電壓可改善加工效率達50%，且不損及加工精度。 Borosilicate glasses (Pyrex glass) are becoming very important in MEMSs and many modern industries due to their anodic bonding properties, transparency and corrosion resistance. However, the inert nature of glass possesses challenges for machining these materials with high accuracy and efficiency, especially in micromachining process. Recently, electrochemical discharge machining (ECDM) has demonstrated to be a potential process for microstructuring of Pyrex glass. However, the key to widening ECDM application lies in how to obtain both high efficiency and machining accuracy. In ECDM process, the discharge phenomenon is closely related with the machining quality and efficiency. The main factors are concluded that the gas film stability and gas film size, in which discharge take place around electrode. This study uses different machining parameters, in order to investigate their inferences on the gas film integrity and to further seek solving tactics. In the drilling process, to improve the quality of ECDM microhole, a flat sidewall-flat front tool electrode was designed to reduce taper phenomena due to the sidewall discharge. Besides, a pulse voltage is applied to improve the heat-affected zone in the rectified DC voltage. The experimental results show that the combination of flat sidewall-flat front tool and pulse voltage conspicuously increases the machining accuracy. The taper angle can be improved to 3 degree. In the microstructuring application, the results indicate that optimum combinations of both pulse voltage and tool rotational rate will realize better machining accuracy. The feasibility of 3-dimensional microstructure machining was demonstrated by a layer-by-layer ECDM micromilling machining. Although pulse voltage is favorable for improving the machining quality, it is hard to obtain an efficient machining rate. The pulse-off (Toff) duration allows the gas film structure to be re-constructed, which makes the sustainability of a dense gas film difficult and results in unstable and unpredictable discharges. In this study a novel pulse voltage configuration, called offset pulse voltage, was applied in the ECDM process to enhance gas film stability and to further promote the discharge performance. Results also show that both the mean machining time and time deviation were decreased around 60 % without sacrificing machining accuracy by an adequate offset voltage.
顯示於類別:	[機械工程研究所] 博碩士論文

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