在采用摩擦配向工艺实现液晶取向的TFT-LCD显示屏中, 外形不规则亮点不良主要有两种: 一种是由可见异物造成的亮点, 可以通过加强摩擦后清洗等改善; 另一种亮点不良并没有伴随可见异物发生。为提升TFT-LCD良率, 亟需明确后者的形成机理并制定改善对策。经分析发现, 此种不可见异物亮点位置处液晶取向异常, 通过进一步对不良区域微观结构和成分的分析, 确认该区域表面有厚约7.5~10 nm的杂质区, 造成液晶取向异常; 然后通过液晶和配向膜取向异常的再现性测试, 锁定摩擦布中背胶和柔顺剂残留是造成液晶取向异常的主要因素, 明确了此不良的发生机理; 最后, 在生产线实际测试了减少背胶和柔顺剂的摩擦布, 非异物亮点不良由0.6%降至0%, 验证了我们的机理推测和实验室测试结果的有效性。

There are two main types of bright dot defects in TFT LCD where liquid crystal is aligned by rubbing process, one is with particles and the other is without particles. The former can be reduced by enhancing cleaning, but the way to reduce the bright dots without particles is barely studied, so research and experiments are performed. According to macro and micro result, the alignment of liquid crystal is abnormal because of impurities as tall as 7.5~10 nm in the defect area. It can be deduced that the abnormally alignment is caused by the remaining of the back coating and the softener agent on the PI surface. Lastly, the rubbing cloth, in which the back coating and the softener agent are reduced, is tested in our factory. The results show that the bright dots w/o particles decrease from 06% to 0% when the back coating and the softener agent in the rubbing cloth are reduced, which proves the effectiveness of the laboratory results and the correction of the mechanism.