P‐181: Study of Polyimide on Improvement of Crushed Bright Spot Mura on FFS Display

In fringe field switching (FFS) displays, the used polyimides possess no side‐trains to guarantee the low pre‐tilt (typically <0.2°), and the photolysis type at 254nm linear polarized ultraviolet is in dominant. The photolysis product was removed during follow‐up oven process with temperature over 200°C. If the photolysis product remains, it will influence the liquid crystal alignment, the liquid will be disordered around the residue, and caused light leakage in dark state of the panel (L0), which is called crushed bright spot mura. In this work, we tried to solve the crushed bright spot mura via three efforts. We developed a new polyimide with low molecular weight diamine, optimized the exposure dose of the ultraviolet intensity, and enhanced the baking time and temperature after ultraviolet treatment, which greatly improves the crushed bright spot mura issue in FFS displays. Our work can be a guidance for LCD display industry in polyimide structure design and high reliability panel fabrication.