LCD玻璃基板之圓弧路徑振動輔助劃線切割研究

Abstract

刀輪劃線乃LCD玻璃基板裂片的主要製程，但其在圓弧路徑劃線上的應用極少，過去的研究已發展出一震動輔助劃線技術，可在厚與薄的玻璃的直線路徑劃線裂片中達到自動裂片與良好表面品質的效果。本研究將其應用在不同厚度玻璃圓弧路徑劃線，探討能達到與在直線路徑上相同的品質，以及達到自動裂片效果的策略，在研究中首先探討劃線速率對不同圓弧劃線半徑大小的影響，再進一步探討振動輔助在圓弧劃線中的影響。觀察徑向與側向裂紋的成長和劃線邊緣的崩落(chipping)來了解玻璃劃線後的表面品質。針對較厚之玻璃：0.5mm提出圓弧半徑常數來了解半徑大小改變彈性成分所產生之中央裂紋深度影響，針對較薄的0.21mm厚度玻璃則進一步以自定義的彎曲測試(bending test)來比較不同振動輔助參數下相對的彎曲強度。 研究結果顯示當劃線速率提高，刀輪轉向時產生扭矩所形成的力會在玻璃上造成徑向與側向裂紋。整體來說，在不改變設備的前提之下，降低速度以降低扭矩所產生的力，則能獲得較好的劃線表面品質，與玻璃厚度無關。加入振動輔助之後，厚玻璃在劃線速率降低至50mm/sec後，可得到自動裂片以及良好的表面品質。但薄玻璃在降低劃線速率後，仍然會有側向裂紋產生，且無法自動裂片。理論上，振動輔助所提供的變動負載能直接將能量傳遞至彈性變型區，實際上仍有部分能量傳遞至塑性變型區，增加塑性變型區範圍，產生缺陷(flaw)，因此當劃線半徑縮小時，路徑重疊率提高造成刀輪再度施力在這些缺陷上，造成缺陷成長為裂紋，降低劃線品質。因此薄玻璃進行劃線時降低振動輔助的振幅大小，則能夠減少傳遞進入玻璃材質的能量，減少缺陷產生，中央裂紋成長較為規則時，自動裂片的可能性就會升高，減少側向裂紋產生，提升表面狀況品質。

Wheel scribing is considered one of the most common glass substrate separation techniques nowadays. However, there is only a few applications referring to circular scribing paths, and currently, there is no relative studies in such functions. The primary subject of this study is to reach the quality similar to the ones acquired in linear paths, and the automatic separation mechanism with vibration assistant for both thinner and thicker glasses. In this study, the effects of scribing speed on different diameters were examined, and followed by how vibration assistant effects upon circular paths. The surface conditions after scribing were examined by observing the growth of radial crack, lateral crack and chippings on the sections of the glass substrate. For thicker glass substrate, circular path constant was proposed to identify the elastic component median crack depth changes; for thinner glass substrate, a custom bending test were introduced to identify the relative bending strengths under different vibration assistant amplitudes. The results show that the radial and lateral cracks would tend to grow more drastically with higher scribing speed due to the forces caused by turning moment. Generally, reducing the scribing speed could reach better surface conditions. The path overlapping rate increases with smaller diameters, and the overlaid residual fields will invoke the adjunct flaws or faults, those were formed by previously scribing process, grow into cracks. This outcome is especially obvious in thinner glass substrates. Lowering the magnitude of vibration assistant amplitude to reduce the energy transmits into the glass can effectively suppress the induction of these undesirable cracks and channel the energy to the growth of median cracks. The median cracks will then be more regular, and the surface conditions will become better and the possibility of automatic separation will thusly increase.