| 摘要: | 放電加工(EDM)是一種極為成熟的技術，其非接觸式加工方式具有明顯的優勢，已被廣泛應用於金屬加工的各個領域中。同時，晶圓邊緣修整在晶圓減薄過程中至關重要，因為不平滑的邊緣會增加邊緣崩裂和損傷的風險，從而降低結構完整性和良率。然而，由於石英晶圓的非導電特性，無法直接進行EDM加工，因此，本研究採用輔助電極的方法，賦予石英晶圓表面導電性，以實現對硬脆石英晶圓的EDM加工修整。
在本研究中，使用六個排除碎屑通道的紅銅管狀電極，針對石英晶圓邊緣進行放電加工修整實驗，實驗設計採用田口法L9直交表，選擇了三個可調整的主要加工參數評估其對表面粗糙度（Ra）、邊緣角度與修整直徑的影響，同時有效減少實驗次數。除此之外，本研究亦導入電極旋轉以增強排屑效率與放電穩定性。在各種轉速條件下，以90 rpm轉速獲得最佳的修邊效果，能顯著降低邊緣崩裂並提升加工一致性。
分析結果顯示，較低的Ton與LV有助於提升表面平整性與尺寸穩定性，而適中的Toff則能在持續放電與碎屑清除之間取得良好平衡，確保穩定的放電狀態。進一步透過灰關聯分析（GRA）獲得多目標最佳品質的加工參數組合，其中灰關聯度（GRG）達0.781，顯示該參數組合在所有品質特徵上均表現出色，具備最佳綜合目標。最終最佳組合為Ton設定為2-1.5-1 μs、Toff為13 μs及LV為0.5 A，在此條件下可獲得1.26 μm（Ra）的最低表面粗糙度與最接近目標值的直徑8.72 mm。為驗證此方法的適用性，亦於相同參數下對不銹鋼薄片進行對照試驗。結果顯示不銹鋼試片具有更平滑的邊緣輪廓，邊緣有輕微毛邊但沒有不規則的形貌，歸因於其導電性與材料特性有助於穩定放電與能量分布，然而，由於其韌性高且材料移除機制不同，加工時間明顯長於石英。整體而言，本研究所提出之輔助電極結合參數優化與電極旋轉設計，證實可成功應用於石英等非導電材料的放電加工邊緣修整。
;Electrical Discharge Machining (EDM) is a highly mature technology widely used in various domains of metal processing, offering significant advantages through its non-contact machining approach. Meanwhile, wafer edge trimming is essential during wafer thinning, as non-smooth edges increase the risk of chipping and breakage, reducing structural integrity and yield. However, direct EDM trimming is not feasible for the quartz wafer due to its non-conductive characteristics. Hence, this study employed a method of assisting electrode to impart conductivity to the surface of quartz wafer, enabling EDM trimming of the hard and brittle quartz wafer.
In this study, a series of EDM edge trimming experiments were performed on quartz wafers using a copper tube electrode with six debris removal channels. A set of systematic experiments based on an L9 orthogonal array of Taguchi method was conducted by selecting three principal machining parameters, namely Ton, Toff, and LV, to evaluate their effects on surface roughness (Ra), edge angle, and trimmed diameter while minimizing the number of trials. In addition, electrode rotation was introduced to improve debris removal and discharge stability. Among the tested rotation speeds, 90 rpm yielded the best trimming results, significantly reducing edge chipping and improving machining consistence.
The analysis revealed that lower Ton and LV significantly contributed to improved surface roughness and dimensional precision, while moderate Toff ensured stable discharge conditions by balancing effective debris evacuation and discharge continuity. This condition was further validated through Grey Relational Analysis (GRA), which yielded a Grey Relational Grade (GRG) value of 0.781, confirming its superiority across all evaluated quality characteristics. The optimal parameter combination, namely Ton set to 2-1.5-1 μs, Toff at 13 μs, and LV at 0.5 A, achieved the best comprehensive performance, including surface roughness of 1.26 μm and a top diameter of 8.72 mm. To further validate the method’s applicability, comparative experiments were conducted using stainless steel sheets under the same parameter settings. The stainless steel sample exhibited a clean and continuous circular profile, with slight burr formation along the edge and no visible surface irregularities. This outcome is attributed to its electrical conductivity and material characteristics, which enabled more stable spark generation and energy distribution. However, its machining time was significantly longer compared to quartz due to its higher toughness and distinct material removal mechanisms. These results confirm the effectiveness of the proposed EDM trimming approach, which employs assisting electrode, for machining non-conductive materials such as quartz, particularly when combined with optimized parameter control and electrode rotation. |
