Brief Introduction Of TFT

Brief Introduction Of TFT

Feb 17, 2017

Brief introduction of TFT-LCD process technology and production process (real AUO factory)


TFT (Thin Film Transistor) LCD thin film field effect transistor (LCD) is a kind of active matrix liquid crystal display (AM-LCD). The liquid crystal display panel, especially TFT-LCD, is currently the only and display more than CRT fully catch up with the comprehensive performance of brightness, contrast, power, life, size and weight, its excellent performance, large-scale production of good properties, high degree of automation, raw materials, low cost, broad space for development, will become the mainstream the product of the new century, is one of the highlights of the twenty-first Century global economic growth.

Main Features

TFT shows the use of "back through" - the way the imaginary light source is not like the TN LCD from top to bottom, but from the bottom up. This approach is set up in the back of the liquid crystal special light pipe, light source when exposed to the light through the polarizer. The electrode under dissection into the FET electrode and the common electrode, the FET electrode is conducted, the performance of the liquid crystal molecules will change, can be light and shading to achieve the purpose of the show, the response time greatly increased to about 80ms. Because of its higher than TN-LCD contrast and more colorful, faster screen refresh rate, the TFT called "true color".

Compared with DSTN, the main feature of TFT-LCD is to configure a semiconductor switch device for each pixel. Since each pixel can be directly controlled by the point pulse. Thus each node is relatively independent and can be controlled continuously. This design method not only improves the response speed of the display, but also can accurately control the display of gray level, which is the reason why the TFT color is more realistic than DSTN.

Main advantages 

With the maturity of TFT technology in the early 90s, the development of color LCD flat panel display, less than 10 years, the rapid growth of TFT-LCD into the mainstream display, which has its advantages are inseparable. Main features are:

(1)good usage characteristics

The application of low voltage, low driving voltage, solid use safety and reliability is improved; flat, and thin, save a lot of raw materials and the use of space; low power consumption, the power consumption is about CRT display 1/10, left and right one percent reflective TFT-LCD even only CRT, save a lot of energy and TFT-LCD products; specification, size series, variety, flexible and easy to use, maintenance, update, easy to upgrade, long service life and many other features. Display range from 1 inches to 40 inches display all application range and large projection plane is full size display terminal; display quality from the most simple monochromatic character graphics to high resolution, high color fidelity, high brightness, high contrast, high response speed of the video display of various specifications; display has a direct type of projection type, perspective, also reflection type.

(2)good environmental protection

No radiation, no flicker, no harm to the health of users. In particular, the appearance of TFT-LCD electronic books and periodicals, will bring human beings into paperless office, paperless printing era, lead to human learning, dissemination and record of civilization revolution.

(3)wide scope of application

It can be used normally in the temperature range from -20 DEG C to +50 DEG C, and the working temperature of TFT-LCD can be reduced to 80 degrees below zero. The utility model not only can be used as a mobile terminal display, but also can be used as a large screen projection tv.

(4)a high degree of automation in manufacturing technology

Large scale industrial production characteristics. TFT-LCD industry mature technology, large-scale production of finished product rate of 90% or more.

(5)TFT-LCD is easy to integrate and update

It is the perfect combination of large scale semiconductor integrated circuit technology and light source technology. At present, there are amorphous, polycrystalline and monocrystalline silicon TFT-LCD, there will be other materials in the future TFT, both the glass substrate and plastic substrate.

TFT Process (thin film transistor process)

1, Array Process (array process)

In the case of AUO, the TFT-LCD panel manufacturing process real factory

Simply put, TFT-LCD panels can be regarded as two pieces of glass substrate sandwiched between a liquid crystal layer, the upper glass substrate with color filter (Color Filter), while the lower glass is inlaid in the upper transistor. When the current changes in the electric field generated by the transistor, liquid crystal molecules resulting deflection of light in order to change the bias polarity, then use Polaroid decision pixels (Pixel) and dark states. In addition, because the upper glass and color filter lamination form each pixel (Pixel) each containing three red blue green color, which emit red blue and green colors constitutes the image pixel on the screen panel.

The three main processes of TFT-LCD:

Anterior segment Array

Array preceding process and semiconductor manufacturing process is similar, but the difference is that the thin film transistors fabricated on glass, instead of silicon wafer.

Middle Cell

The middle section of the Cell, is the previous paragraph Array glass as substrate, and the color filter glass substrate, and between two glass substrate into the liquid crystal (LC).

Post Module Assembly (module assembly)

After the module assembly process is the process after the glass Cell and others such as backlight, circuit, frame and other components assembly production.

TFT-LCD panel production process

Thin film transistor liquid crystal display (TFT-LCD) module

Thin film transistor liquid crystal display module

TFT-LCD: sandwich structure

Liquid crystal display structure as a sandwich, the liquid crystal sandwiched between two glass substrates, the two glass substrate is TFT Array glass and color filter. TFT Array glass above a myriad of pixels (pixel) arranged, the color filter is the source of the color screen, the LCD will be sandwiched between the TFT and Array color filter. When the voltage applied to TFT (transistor), liquid crystal steering, then the light passes through the liquid crystal panel to produce a pixel, and the light source module is responsible for providing the backlight. At this time, the color filter of each pixel given a specific color. With a different color for each pixel of the image of the front panel is.

TFT-LCD: sandwich structure

After more than 300 processes

The TFT-LCD must be manufactured in a clean, clean room with more than 300 processes. Clean room cleanliness, the highest level up to "10", that is, in the clean room environment, each cubic foot only 10 dust.


After more than 300 processes

TFT-LCD factory - generation and size

The TFT-LCD plant has evolved from the past 1 generations to the present generation of the 7.5 generation. The difference between the generations is the size of the glass substrate. The larger the glass substrate, the larger the size of the panel can be cut. For example, a 7.5 generation glass substrate size up to 195 cm X 225 cm, the size of more than one double bed to increase, it can be cut into eight pieces of 42 inch panel, or 6 pieces of 46 inch panel.

TFT-LCD factory – generation and size

TFT-LCD Front-end process——Array

The manufacturing process of TFT-LCD can be divided into three stages: pre Array, middle Cell, and post module assembly. The Array process is similar to the semiconductor process, but the difference is that the thin film transistors on glass, rather than on silicon wafers.

TFT-LCD Front-end process——Array

TFT-LCD -Midcourse process——Array

The middle section of the Cell, is the previous paragraph TFT Array glass as the substrate, and the color filter glass substrate, and the two pieces of glass substrate between the liquid crystal on the substrate, and then cut into a large glass panel.

TFT-LCD middle process Cell

TFT-LCD post process - module assembly

After the module assembling process, is the Cell veneer with glass after cutting, and other components such as circuit board, backlight, frame and other components of the assembly production.