小尺寸TFT-LCD GOA显示屏不良横纹的研究

Horizontal stripes defect of small size TFT-LCD GOA panel

随着GOA(Gate On Array)技术的不断发展,在小尺寸TFT-LCD窄边框显示屏上的应用也越来越频繁,但是由于GOA电路的复杂性和TFT器件自身的稳定性,以及外界温度、湿度的影响,显示屏还存在显示不稳定的问题。本文针对小尺寸TFT-LCD GOA显示屏在高温高湿环境下产生的异常显示横纹,进行了深入分析与改善研究。通过对GOA区域ITO过孔电阻测试、显微镜检查以及修复实验验证,找出了不良产生的直接原因为ITO发生腐蚀,过孔电阻增大,导致GOA驱动信号无法上下导通。接着进一步研究ITO腐蚀发生的条件、ITO腐蚀情况、驱动信号对应关系以及腐蚀成分,证明了ITO发生腐蚀原因为产品长期工作(200h左右)在高温高湿环境下,由于水汽的不断渗入,使GOA区域ITO发生了电化学腐蚀效应。最后根据电化学腐蚀原理,通过采用隔水性强的封框胶、增加ITO膜厚以及降低ITO电位差等措施对工艺进行了改善,结果表明改善后的显示屏超过1 000h,未发生ITO腐蚀。

With the development of GOA technology,more and more GOA unit has been applied to small size TFT-LCD product.However,the display screen has an unstable display problem which is ascribed to the complicated GOA circuit configuration,characteristics and environmental factors such as temperature and humidity.In this paper,a horizontal stripes defect caused by GOA in display was deeply researched and the improving methods were given.This unusual phenomenon was related to corrosion of ITO in the GOA unit which induced ITO resistance to be too large and eventually the drive signal can’t be output normally.Further research found that the electrochemical reaction would take place on ITO due to the continuous infiltration of water vapor through the GOA area in the high temperature and high humidity environment.Finally,according to the principle of electrochemical corrosion,the method of using water-repellent sealant was put forward,meanwhile the adjustment of increasing of the ITO’s thickness and decreasing of the potential difference prevent corrosion of ITO in GOA,which made the product’s working time increase from 200 h to 1 000 h.