Abstract— Mura defects become visible in a 13.3‐in. TFT‐LCD using chip‐on‐glass (COG) packaging when the thickness of the glass substrate is decreased from 0.5 to 0.3 mm. Mura, the non‐uniform brightness in LCDs, is caused by COG packaging due to the mismatch of the coefficient of thermal expansion (CTE) and Young's modulus between the glass substrate and the IC‐driver Si chips. In this paper, a 3‐D finite‐element‐analysis (FEA) model, coupled with transient thermal analysis is first established to examine the warpage and stress behavior in the upper‐glass‐plate post‐COG‐package processing for identifying the root causes of the light‐leakage phenomenon. Prior to that, the simulated warpage results are validated by surface‐contour measurement. Data and modeling results show that a low bonding temperature together with a low modulus in novel ACF materials can effectively eliminate Mura. Besides, thinner silicon or a shorter length of Si chips as drivers offers enhanced reduction in the localized warpage, and thus can be a practical and low‐cost solution for eliminating mura defects.

In this paper, we discuss the light leakage issue of LCD panel occurred due to sharp temperature gradient and non-uniform stress distribution. By using numerical analysis and experiments, the relationship between light leakage and temperature gradient has been discovered. Thermal and stress simulations are applied in the analysis of light leakage phenomenon. Besides, we use simulation tools to predict the effectiveness of solutions for reducing the temperature gradient and stress distribution of LCD glass substrates. Finally, light leakage has been improved by using the rear frame with high thermal conductivity to reduce the temperature gradient and stress of the LCD panel.

Gravity mura is a typical defect in large-sized LCD which causes non-uniform shades at underside. In this investigation, a mechanical model was proposed and analyzed under gravity and thermal expansion. The stiffness and arrangement of photospacers were considered in this model. Furthermore, the simulation results were obtained to modify the analytical model properly. The analytical results facilitated the establishment of the design criteria of LCD cells for which the gravity mura could be restrained or eliminated.

An analytical model of an LCD cell under gravity and local loading to prevent permanent deformation of the photospacers and the occurrence of gap mura will be presented. The analytical model is established from the Winkler model, which is composed of a beam and a series of springs. The analytical solutions have been simplified under specific assumptions and modified through threedimensional simulations in order to improve their accuracy. Therefore, the analytical model can be applied to the design of an in-cell touch panel while considering the local loading due to touch or probe testing and contact conditions of photospacers. This analytical model can be used to provide instant design criteria for photospacers without considerable simulation and experimental data and to enhance the reliability of the LCD cell structure. FIGURE 1 -(a) LCD cell under gravity and local loading; (b) analytical model of the LCD cell.

A numerical model has been developed to improve the quality of LCD module. By performing CFD analysis, heat transfer behavior for LCD module had been clarified. Designer can solve the issue of heat concentration produced by the electrodes of L shape CCFL to avoid the liquefaction of liquid crystal and the failure of compensation film. Experimental data is used to compare with simulation results and have a consistency in temperature distribution. The developed model has been used to predict the temperature distribution and evaluate the effects of different designs.