Analysis of fracture mechanisms of ultrathin glass for flexible cover window under pen drop conditions

Abstract

The fracture mechanism of a chemically strengthened ultrathin glass (UTG) for the cover window of flexible display devices was investigated under pen loading conditions for the first time to better understand the UTG impact resistance characteristics. High‐speed camera analysis, fracture fragment analysis, and finite element modeling were employed to investigate the fracture mechanism of the UTG under pen drop conditions. A pen‐on‐plate (POP) test was also employed to examine the fracture characteristics under static loading condition, and its results were compared with those of the pen drop test (PDT) to find a correlation between the static and dynamic loading conditions. The correlation found between the POP and PDT tests indicates that a quantitative estimation of contact displacement under PDT can be obtained by measuring the first ring crack size, to more easily determine the impact resistance characteristics of UTG.

18‐1: Composite UTG Cover Window Selectively Reinforced with Glass‐Cloth for Improvement of Both Pen‐Drop Resistance and Foldability

“…After a 4.5g ball pen was dropped on to the films from given heights, the cover window was observed using a microscope. Considering the fracture mechanics of UTG cover window, we categorized two different pen drop heights: initiation height is when small cracks begin to form, propagation heigh is when UTG shatters and large cracks are formed throughout the whole UTG [13].…”