藍寶石基板具有硬脆特性，特別是在微細加工上，若以傳統之機械加工方法將非常困難對其加工，本研究目的為發展電化學放電加工藍寶石基板微孔之技術，採用直徑50 μm之碳化鎢圓柱工具電極進行啄鑽式電化學放電加工藍寶石基板之研究，並且進行一系列加工參數之實驗，期望獲得較深之加工深度與較小之微孔入口孔徑。本研究進行啄鑽式電化學放電微孔加工時，係採用單因子實驗分析，探討各種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藍寶石基板加工後之品質特性影響，品質特性則包括有微孔入口孔徑、加工孔深及工具電極長度消耗情況等。
為了改善在微孔加工中後期由於電解液更新不良導致加工能力差，工具電極直接觸碰到工件表面進而斷裂，造成加工深度受限的情形發生，本研究採用啄鑽式進行電化學放電微孔加工，藉由於工具電極向下行走一定距離後，向上抬升工具電極，不僅可以增加電解液進入微孔孔內的空間，並且在抬升的過程孔中，會產生負壓促使電解液流入微孔中，達到促進電解液補充與更新的效果，提升加工孔深與材料移除率，實驗結果顯示利用啄鑽之進給方式加工，能夠有效提升加工能力與改善工具電極斷裂之情況，並且能獲得較佳的加工深度，在工作電壓48 V、進給速率1/8 µm / s、脈衝週期10 µs、衝擊係數50 %及主軸轉速50 rpm之下，具有較佳加工孔深與微孔入口孔徑，並於工具電極之進給總行程增加後，能夠成功完成厚度200 µm藍寶石之通孔加工。

Sapphire is a material that has hard and brittle properties. The traditional machining method can hardly process sapphire substrate, especially in micromachining. Therefore, this study aims to develop the technology of electrochemical discharge machining (ECDM) micro-holes on the sapphire substrate. To perform ECDM with peck drilling, a cylindrical tungsten carbide rod with a diameter of 50 µm was used as a tool electrode. A series of studies on processing characteristics were carried out to obtain deeper machining and smaller hole diameters. Additionally, peck drilling with ECDM has been done using a single-factor experiment. The effects of the voltage, feed rate, duration time, duty factor, and rotational speed on the diameters of the micro-hole, machining depth of the micro-hole, and length of tool electrode consumption were discussed.
In this study, ECDM was combined with peck drilling to eliminate the breakage of tool electrodes and hole depth limitations caused by inadequate electrolyte renewal during the later process stage. The tool electrode will lift above the workpiece surface after machining a certain distance. This phenomenon could not only increase the space of the micro-hole into which the electrolyte goes but also generate a negative pressure to promote the electrolyte into the micro-hole during the lifting process. The electrolyte renewal, depth of the micro-hole, and material removal rate can be improved using this method. The experimental results show that the processing capability could be effectively improved, the breakage of tool electrodes could be avoided, and the depths of micro-holes could be deepened by using the peck drilling method. Better diameters and a deeper depth of micro-hole could be obtained at a voltage of 48 V, feed rate of 1/8 µm / s, duration time of 10 µs, duty factor of 50%, and rotational speed of 50 rpm. After extending the working depth, the better parameters combination mentioned above allow for the through hole machining of sapphire substrate with a 200 µm thickness.

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