The quality improvement of PI coating process of TFT-LCD panels with Taguchi methods

This study applied Taguchi methods to improve the quality of PI (polyimide) coating processes for TFL-LCD (thin-film transistor liquid-crystal display) panels, which could prevent low yield due to adjustments of cleaning machine brush indentation for chipping. The optimal process conditions were obtained by the Taguchi methods in order that alignment film printing can achieve the best product quality at the lowest cost. Experiments were conducted, based on a number of defects on printed alignment film, for the impacts of various conditions of Taguchi experiments on quality. The Fourier analysis was performed in an optical inspection machine to determine the defects in the deposition of an alignment film layer. This study employed the Taguchi method to improve alignment film printing process parameters and production yield, and control a cell particle derived long-term product scrap level below 0.2%, as well as lower NG and line repair probabilities.