Characterization of the Flexural Strength and Fatigue Life of Ultrathin Glass After Dicing

Abstract

Ultrathin glass (UTG) exhibits a great potential for use as a substrate for emerging consumer electronics for weight and profile reduction and flexibility or bendability enhancement. However, the brittle nature of UTG poses critical challenges during fabrication and operation. This study aims at investigating the cut edge/sidewall quality, ultimate flexural strength, and flexural fatigue life of UTG after dicing through finite-element analysis (FEA) and experiments. The focus is placed on the effects of dicing techniques, i.e., mechanical dicing, picosecond laser dicing, and wet etching. The ultimate flexural strengths of these diced UTGs are characterized using two-point bending (2PB) and three-point bending tests. In addition, their dependence on the UTG thickness and loading rate is also addressed. Furthermore, a surface treatment process is applied in an attempt to improve the cut edge/sidewall quality and even the ultimate flexural strength of the diced UTGs. At last, the maximum bending stress and flexural fatigue life of the diced UTGs at different bending curvatures, cyclic loading frequencies, and temperatures are assessed via FEA and cyclic 2PB fatigue test, respectively, by which the stress–fatigue life relationships are established.