| 摘要: | 藍寶石基板具有特殊機械性質如硬脆特性等，特別是於精微加工上，若以傳統之機械加工方法對其加工將非常困難，本研究目的為發展電化學放電加工藍寶石基板數十微米級的微孔加工之技術，採用直徑40 μm之碳化鎢圓柱形工具電極及磁場輔助方式進行，並進行一系列加工之實驗，希望能獲得較佳品質之數十微米級的微孔。本研究係藉由磁場輔助方式進行電化學放電藍寶石基板微孔加工單因子實驗分析，並探討各個加工參數如工作電壓、進給速率、脈衝週期、衝擊係數以及主軸轉速等對於藍寶石基板微孔加工之品質特性影響，加工品質特性包含微孔的入、出口孔徑及工具電極損耗情形。
電化學放電應用於數十微米級的微孔加工時，由於工具電極與工件間之加工間隙相當小，不利於電解液流入電極前端之加工區域，導致加工區域內電解液不足而無法形成絕緣氣膜，造成電極前端撞擊加工工件而斷裂，無法進行藍寶石基板電化學放電微孔加工，因此本研究採用磁場輔助電化學放電加工進行藍寶石基板微孔加工之研究，實驗結果顯示利用磁場輔助方式加工，透過磁場所產生之勞倫茲力作用，可以促進電解液流動循環及工具電極表面之絕緣氣膜薄化，從而改善數十微米級寶石電化學放電微孔加工能力與加工品質，並能夠成功完成厚度50 µm藍寶石基板之通孔加工，於工作電壓43 V、進給速率1/8 µm/sec、脈衝週期20 µs、衝擊係數30 %及主軸轉速100 rpm之最佳加工參數組合下，可獲得微孔入口平均孔徑為 78 μm，以及微孔出口平均孔徑為 41 μm之較佳微孔孔徑。
;Sapphire substrates possess unique mechanical properties, including hardness and brittleness, and therefore, they are particularly challenging to process using conventional mechanical machining methods, especially in terms of microfabrication. In the current study, a microhole fabrication technique involving electrochemical discharge machining (ECDM) was developed to enable fabrication of sapphire substrates at tens of microns scale. A cylindrical tool electrode made of tungsten carbide with a diameter of 40 μm was used, and magnetic field assistance was implemented. A series of experiments were then conducted to identify a means of improving the quality of the tens of microns scale microhole fabrication. This study conducted a single-factor experimental analysis of the effectiveness of using ECDM with magnetic field assistance to fabricate microholes on sapphire substrates. The influences of several machining parameters, including voltage, feed rate, duration time, duty factor, and rotational speed, on the quality characteristics of the microhole fabrication on sapphire substrates were investigated. The quality characteristics included the inlet and outlet diameters of the microholes and the wear of the tool electrode.
Generally, when ECDM is used to fabricate microholes at the tens of microns scale, the small gap between the tool electrode and workpiece is bad for the flow of electrolytes into the machining area near the electrode tip. This insufficient electrolyte flow prevents the formation of an insulating gas film, resulting in collisions between the electrode tip and the workpiece, which in turn leads to fractures and renders the ECDM of microholes on sapphire substrates infeasible. Therefore, in the current study, magnetic-field-assisted ECDM was used to fabricate microholes on sapphire substrates. According to the experimental results, when magnetic field assistance was used, the generated Lorentz force promoted electrolyte circulation and facilitated thinning of the insulating gas film on the surface of the tool electrode. Consequently, the capability and quality of ECDM for microhole fabrication on sapphire substrates at the tens of microns scale were improved. Through holes were successfully fabricated on sapphire substrates with a thickness of 50 µm. When the optimal combination of machining parameters was used, including a voltage of 43 V, feed rate of 1/8 µm/sec, duration time of 20 µs, duty factor of 30%, and a rotational speed of 100 rpm, microholes with average inlet and outlet hole diameters of 78 and 41 μm, respectively, were fabricated. |
