| 摘要: | 本論文為使用高功率超音波輔助振動線電極，對SiC晶圓工件進行線切割放電切槽加工研究，並探討線切割加工參數如開路電壓、超音波功率、線張力段數、SiC晶圓厚度等，於加工品質特性包括有加工時間、材料移除率及加工槽寬度等，以及進行加工後熱影響區深度量測，並探討有、無超音波輔助加工對SiC晶圓材料之影響。
實驗結果顯示，在SiC晶圓工件厚度為0.42mm時，無超音波輔助加工結果是優於有超音波輔助，原因在於無超音波輔助情形下，線電極側向振動較小，使得放電現象集中於線電極的行進方向，故不會造成側向放電頻率增加，線電極於加工區停留時間較短，在適當的加工參數下，相較於有超音波輔助加工時，加工槽寬度減少了約8%，加工時間縮短了約22%，料移除率增加了約12%。
當採用SiC晶圓工件厚度為10.0mm進行加工實驗時，有超音波輔助加工結果是優於無超音波輔助，原因係在於超音波輔助振動線電極時，線電極振動可加速放電渣的排除，因此減少了集中放電現象，故在加工較厚之SiC晶圓工件時，採用超音波輔助及選用適當的加工參數下，相較於無超音波輔助加工時，加工槽寬度減少了約10%，加工時間縮短了約13%，材料移除率增加了約8%，且熱影響深度更淺，並能夠獲得的最小熱影響深度為2μm。
;This study employed high-power ultrasonic vibration-assisted wire electrical discharge machining for creating grooves on SiC wafers. The influence of processing parameters open voltage, ultrasonic power level, wire tension level, and SiC wafer thickness on the machining time, material removal rate, and kerf width was investigated. Furthermore, the depth of the heat-affected zones was measured after the processing, and the effects of ultrasonic vibration-assisted processing and processing without ultrasonic vibration assistance on the SiC wafer material were determined.
The experimental results revealed that when the thickness of the SiC wafer workpiece was 0.42 mm, a better result was obtained when ultrasonic vibration assistance was not applied than when it was. This was because in the processing without ultrasonic assistance, the lateral vibration of the wire electrode was small, meaning that the discharge phenomenon exhibited a parallel direction to the wire electrode; thus, the frequency of lateral discharge was not increased, and the wire electrode was operated for less time in the processing area. When using the most appropriate combination of processing parameters, the processing kerf width was 8% lower, the machining time was 22% shorter, and the material removal rate was 12% higher for nonassisted processing than for ultrasonic vibration-assisted processing.
When a SiC wafer workpiece with a thickness of 10.0 mm was used in the processing experiments, the opposite result was obtained processing with ultrasonic vibration assistance was better than that without. This was because the ultrasonic waves helped vibrate the wire electrode, and this added vibration accelerated the removal of debris, leading to less-concentrated discharge. When processing thicker SiC wafer workpieces by using ultrasonic vibration assistance with an appropriate combination of processing parameters led to 10% lower processing kerf width, 13% shorter machining time, and an 8% higher material removal rate when compared with processing without the assistance. The heat-affected depth was shallower, and a minimum heat-affected depth of 2 μm could be obtained. |
