以飛秒雷射進行軟性基板微加工之研究 ; Study of micro-machining on flexible substrates by using a femtosecond laser

本論文利用飛秒雷射在軟性基板上製備微孔洞，藉由改變雷射加工參數，分析雷射加工對於微孔洞表面形貌的影響。由於軟性基板具備可撓性、適型化等特性，在近年被廣泛應用；然而，由於高分子材料抗酸蝕性差的特性，導致軟性基板不適用於化學濕蝕刻製程，因此研究雷射加工對於軟性基板的孔洞成形技術，將是未來工業技術的發展趨勢。 由於短脈衝雷射加工的孔洞較長脈衝小，而且具備熱效應較低的優勢，故本論文選擇飛秒雷射進行雷射加工，以研究在不同偏振態、聚焦位置的條件下，對微孔洞結構的影響。結果顯示，雷射加工的偏振態會影響切割深度；聚焦的位置越深得到的孔徑越小，且下表面孔洞邊緣較為均勻且無不規則的熔融狀。運用在鍍銀及鍍銅PET軟性基板上獲得的結果與經驗，進一步對聚苯醚多層疊合基板進行盲孔製備，在最佳參數：脈衝能量密度5.3 mJ/cm2、聚焦位置25 μm、雷射掃描速度80 μm/s（脈衝密度62.5 pulses/μm）的圓偏振光加工下，可製備出底部無碳殘留、不傷及銅層，銅層含氧量為12.6%的盲孔洞。 ; In this thesis, the femtosecond laser pulses with lower thermal effects are utilized to produce micro holes on flexible substrates. After laser micro-machining, the morphology of micro holes with different laser machining parameters was analyzed. Flexible substrates have been widely used in recent years due to the deformable and bendable properties. However, since polymer materials lower acid corrosion-resistant property, the wet chemical etching processes cannot be applied to the flexible substrates. Laser machining is a potential technology and could be further used for the fabrication of holes on the flexible substrates. By changing the laser polarization and focus position, the through holes and micro structures have been successfully fabricated on the silver- and Cu-coated PET substrates. The results show that the hole size and cutting depth are polarization- and focus position-dependent. Additionally, the holes without molten edge can be achieved by femtosecond pulses. We further fabricated the blind via holes (BVH) on polyphenylene ether (PPE)/Cu/Teflon fiber/Cu multi-layer substrates by femtosecond laser micro-machining. The optimal machining conditions are laser fluence of 5.3 mJ/cm2, focus position of 25 μm, laser scanning velocity of 80 μm/s (laser pulse density is 62.5 pulses/μm). Finally, a BVH with the oxidation rate ~ 12.6%, no carbon residue on the bottom of the hole and no damages on Cu layer has been obtained.