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What is the TFT LCD Display manufacturing process?

Views: 444     Author: Reshine Display     Publish Time: 2023-10-25      Origin: Site


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What is the TFT LCD Display manufacturing process?

Nowadays, you can find a display screen almost anywhere. Do you remember TVs or computer monitors from 20 years ago? They were massive, quadrate, and heavy. Now consider the flat, thin, and light screen in front of you; have you ever wondered why there is such a significant difference?

CRT (Cathode Ray Tube) displays, which required a large space to run the inner component, were used in monitors 20 years ago. And now the screen in front of you is an LCD (Liquid Crystal Display) screen.

What is LCD?

As previously stated, LCD is an abbreviation for Liquid Crystal Display. It is a new display technology that takes advantage of the optical-electrical properties of liquid crystals.

Liquid crystal is a state of matter that possesses both liquid and solid crystal properties. It does not emit light, but it can allow light to pass perfectly in one direction. Meanwhile, liquid crystal molecules will rotate under the influence of an electric field, causing light to rotate as well. However, the liquid crystal can function as a light switch, which is essential in display technology.

LCD Types

LCD has been developed for decades. There are three types of LCDs: TN LCD, STN LCD, and TFT LCD.

1. Twisted Nematic LCD: TN stands for Twisted Nematic. It is an old and simple technology that can only display white and black and is used in small items such as calculators.

2. STN LCD: STN is an abbreviation for Super-twisted Nematic. STN LCD's liquid crystal rotates at greater angles than TN LCD's and has a different electrical feature, allowing STN LCD to display more information. STN LCD has many improved versions, such as DSTN LCD (double layer) and CSTN LCD (color). Many early phones, computers, and outdoor devices used this LCD.

3. TFT LCD: TFT is an abbreviation for Thin Film Transistors. It is the most recent generation of LCD technology and has been used in all display scenarios such as electronic devices, automobiles, industrial machines, and so on. When you see the word "transistor," you may realize that TFT LCDs contain integrated circuits. That is correct, and the secret is that TFT LCDs have the benefit of high resolution and full color.

Now that TFT LCD has the largest application market, let's take a step back and look at the TFT LCD manufacturing process.

The TFT LCD manufacturing process

TFT LCD can be divided into three parts, from bottom to top: the light system, the circuit system, and the light and color control system. We'll begin with the inner light and color control system and work our way out to the entire module during the manufacturing process.

It is common to divide the TFT LCD manufacturing process into three major components: array, cell, and module. The first two steps involve the creation of a light and color control system called a cell, which includes TFT, CF (color filter), and LC (liquid crystal). The final step is to put the cell, circuit, and light system together.

1. Array

To increase productivity, we'll perform a series of procedures on a large glass, which will be cut into smaller pieces in the next step.

First, allow me to introduce you to an important resource, ITO. ITO, an abbreviation for Indium Tin Oxide, has electrical conductivity and optical transparency, as well as the ability to be easily deposited as a thin film. As a result, it is widely used to create circuits on glass.

Let us now look at TFT and CF production. The PR (photoresist) method is a popular technique. The entire PR method will be demonstrated in TFT production.

TFT: Arrange semiconductor material and ITO on a glass substrate in the desired order.

Coating with photoresist.

Partially expose the photoresist, then clean the exposed photoresist.

Remove the semiconductor and ITO without the photoresist cover to form part of the circuit.

Remove any remaining photoresist.

We frequently have to repeat the steps 5 times to complete the circuit.

CF: Using the PR method, create a black matrix as the boundary on the glass substrate.

Using the PR method, coat red, green, and blue materials separately within the black matrix.

Coat the RGB (red, green, and blue) layer with an overcover.

Install an ITO circuit.

2. Cell

In this step, we'll assemble the TFT and CF glass while also filling in the LC.

Coat polyimide film on the ITO side of both TFT and CF glass to constrain the initial direction of the LC molecule.

Create a boundary for LC on both glasses with glue. Apply one more layer of conductive adhesive to the CF glass. This allows the LC molecule to communicate with the control circuit.

Fill LC up to the limit.

Connect two pieces of glass, then cut the large glass into small pieces by the standard.

Polarizer film should be applied to both sides of the incised glass.

3. Module

Connect the cell to the circuit system first.

Connect the cell to the driver-integrated circuit.

Connect the FPC to the outer PCBA (printed circuit board assembly).

Prepare the lighting system next

Attach the light source, which is usually an LED or a CCFL, to a light guide plate with a reflector film underneath.

Place the diffuser and prism films on the light source in that order. These two films are used in conjunction with reflector film to convert point light from the light source into area light and increase light intensity.

Connect the light source to the light control circuit, which is always a different type of PCBA.

Finally, we must assemble everything with the screen frame and run an aging test.

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