Glass substrate is the most basic material of TFT LCD, and its quality affects the qualification rate of the whole project directly.Next, we will briefly introduce the glass substrate of TFT LCD.
1.The basic conditions of glass substrate
The glass substrate of TFT LCD display must meet the following conditions at the same time:
1）. The light transmission efficiency shall reach more than 98% to ensure the light utilization efficiency of the LCD display.
2）. It has the heat resistance of above 350 degrees, ensuring no deformation in the production process within 300 degrees.
3）. With a certain acid and alkali resistance, to ensure that the production of acid and alkali drugs corrosion.
4）.The length and width can be more than 1M to ensure the cutting efficiency and large size of LCD.
5）. The thickness can be below 0.7mm with sufficient flattening.
6）.The technology of mass production is an essential element of modern industry.
2.Quality requirements of glass substrate
TFT LCD has high requirements on glass substrate, mainly including material characteristics, substrate shape, and process quality.
1). Material properties: In terms of optical properties, the transmittance of glass should be as high as possible to reduce the brightness loss from backlight.In terms of thermal characteristics, the lower the thermal expansion coefficient, the better, so that TFT LCD substrate size more stable.Reduce the thermal shrinkage as much as possible to improve the heat resistance of the glass substrate, because the thermal shrinkage will affect the characteristics and graphic precision of TFT devices.In terms of mechanical properties, it is mainly the density of glass substrate. The smaller the density of glass substrate, the smaller the amount of warping of the substrate during the production of TFT LCD, the easier the handling, and the lighter the weight of the LCD.
2).Substrate shape: In terms of external dimension, TFT side and CF side generally adopt the same glass substrate due to different types of glass substrate with different thermal expansion coefficients.If different types of glass substrates are used, the position deviation of the counterpoint pattern will occur due to the different size variations.If the position deviation is large, light leakage will occur.In terms of flatness, the thickness deviation of the glass substrate should be as small as possible, which will adversely affect the lithography on the TFT substrate.The warping and undulation of the glass substrate shall not exceed the required specification range, otherwise it will cause uneven display and decrease the quality of the display screen.
3).Process quality: The process quality of the glass substrate is not only the requirement of the surface of the substrate, but also the requirement of the glass interior.The surface pollution, scratch, bump and dust particles of the glass substrate must be within the scope of specifications.Inside the glass substrate, bubbles and foreign matter formed in the manufacturing process will mix into the glass substrate. After exceeding a certain specification, it will affect the directness of backlight and cause light scattering, thus reducing the brightness of TFT LCD.
In order to do a good job in quality control in the manufacturing process of glass substrate, the allowable size of various defects must be less than the minimum line width and minimum line spacing in the LCD screen.The above is a brief introduction to the glass substrate of TFT LCD display from the aspects of the basic conditions and quality requirements of the glass substrate.I hope to help you understand the knowledge and principle of liquid crystal screen.About the industrial LCD customization, selection, angle of view and any other problems and needs, welcome to consult technical personnel of Disea, we will provide you with the best LCD solutions.