利用表面蝕刻消除於雷射藍寶石研磨加工產生之應力

The Application of Etching on theReduction of Residual Stresses inmechanically polished Sapphire CoverGlass Chamfered with Laser

藍寶石是一種質地堅硬的防刮材料，通常用作手持消費性電子設備的表面覆蓋玻璃。加工程序通常需要使用金鋼石漿料進行機械拋光以產生鏡面，並且機械研磨有時需要在邊緣處進行額外的倒角。這些工序除了導致殘餘應力，亦將降低藍寶石工件的機械強度。本研究採用磷酸濕式蝕刻法，以減少一英吋直徑藍寶石玻璃蓋板工件在機械拋光和雷射研磨中所產生的應力。此應力通常在通過皮秒雷射對邊緣進行倒角之前所進行對藍寶石之拋光所產生。本文在不同的加工階段，利用雷射曲率法測量殘餘應力。由實驗結果顯示，濕式蝕刻法能有效緩解應力，不會因雷射加工而引起嚴重的殘餘應力。

Sapphire is a tough and anti-scratch material commonly used as cover glass of mobiledevices such as watches and mobile phones. A mechanical polishing using diamond slurryis usually necessary to create mirror surface. Additional chamfering at the edge issometimes needed by mechanical grinding. These processes induce residual stresses andthe mechanical strength of the sapphire work piece is impaired. In this study wet etchingby phosphate acid process is applied to relieve the induced stress in a 1” diameter sapphirecover glass. The sapphire is polished before the edge is chamfered by a picosecond laser.Residual stresses are measured by laser curvature method at different stages of machining.The results show that the wet etching process effectively relieves the stress and the lasermachining does not incur serious residual stress.