A Study On The Mechanism And Improvement Of Liquid Crystal Bubbles In TFT LCD

With the high generation of TFT-LCD production lines and people's increasing requirements for product performance,more stringent requirements have been put on product design and production processes.It is accompanied by high-frequency defective products,which bring unprecedented challenges to the production of products.Liquid crystal bubbles,as a common defect,are affected by many factors in the production process,and are also closely related to product design and production processes,causing many difficulties for poor solution work,and the improvement program is also subject to many restrictions.In this paper,we use liquid crystal blister defects to measure the relevant performance parameters of the panel,such as thermogravimetric analyzer,box thickness tester,FTIR(Fourier transform infrared spectroscopy),SEM(Scanning electron microscope),and FIB(Focused Ion Beam),to determine the mechanism of failure,panel design,and production control.The parties conducted targeted analysis and discussion in a targeted manner and proposed corresponding improvement plans,which have positive significance in preventing the occurrence of such defects.After the analysis of the liquid crystal bubble generation mechanism,the liquid crystal bubble defects are divided into two major categories: air bubbles and vacuum bubbles.Aiming at the problem of air bubbles,this paper conducts a series of experimental tests on the sealing material in liquid crystal displays,and summarizes the methods to solve the problem of air bubbles caused by abnormal sealant,and provides methods for how to select the sealant materials.In addition,through structural analysis and experimental testing of the color resist material in the liquid crystal cell,the solution to solve the air bubble problem caused by the color separation of the gas in the liquid crystal cell is solved.The key to solve air bubbles lies in the following two points: 1).The liquid crystal cell sealing method needs to withstand the reliability verification,and no liquid crystal bubbles will occur due to the outside air entering the liquid crystal cell.2).Organic substances such as color-resistance in the liquid crystal cell are required to withstand the verification of reliability,and no change in external temperature or pressure causes the organic substance to sublimate into a gas,thereby generating liquid crystal bubbles.For the vacuum bubble problem,this paper establishes a model analysis of the liquid crystal dripping range(LC margin),and the main influence factors: Main PS(Main Photo Spacer)height,Sub PS(assisted PS)height,and association between PS and different liquid crystal dripping amount sex conducts experimental testing to find the best matching relationship,and summarizes the key points to solve the vacuum bubble problem in the following two points: 1).The space design of the liquid crystal cell conforms to the specifications and is consistent with the shape variables of the liquid crystal cell under external temperature and pressure.2).The space in the liquid crystal cell and the amount of liquid crystal dripping need to reach a balance point to avoid the vacuum bubble as the liquid crystal cell volume is too large and the liquid crystal volume is too small.The main achievements of this paper are as follows:(1)The sealant coating operation specification is summarized: Liquid crystal celladhesion test method and evaluation method;We summarize the adhesive pressurecorresponding to the width of the sealant,and obtain the specifications for thesealant width control required for liquid crystal panels of different sizes.(2)A new product design specification is summarized: The design of the PV2(SiNx)layer opening on the product,the organic matter in the liquid crystal cell iseliminated from the small hole before the upper and lower panels combination.(3)New LC margin(liquid crystal dropping range)management specification issummarized: Different Main PSH(Main Photo Spacer Height)and Sub PSH(MainPhoto Spacer Height)were used to design the experiment with the amount of liquidcrystal dropping.After the experiment,the best drop range of the liquid crystal wasobtained and the problem of vacuum bubbles in the production process was reduced.