Introduction to the manufacturing process and purpose principles of liquid crystal modules (LCM)

What is LCM?

LCM (LCD Module), namely LCD display module and liquid crystal module, refers to a component that assembles liquid crystal display devices, connectors, peripheral circuits such as control and drive, PCB circuit boards, backlights, structural parts, etc.

Common terms used in the manufacturing process of liquid crystal modules (LCM)

TFT—–Thin Film Transistor: thin film transistor

CF——-Color Filter: color filter

LCD—–Liquid Crystal Display:LCD display

TAB—–Tape Automatic Bonding: Load package IC

PCB—–Printed Circuit Board: Printed circuit board

ACF—–Anisotropic ConductiveFilm: anisotropic conductive film

B/L——Back Light:Backlight module

Assy—Assembly: Assembly

B/Z——Bazel: Iron frame

Bonding: pressing

The three stages of “front, middle and back” of TFT-LCD manufacturing

As shown in the picture above, the back-end Module process is mainly the integration of the LCD substrate’s driver IC and the printed circuit board. This part can transmit the display signal received from the main control circuit to the driver IC, driving the liquid crystal molecules to rotate and display images. In addition, the backlight part will be integrated with the liquid crystal substrate at this stage, and the complete LCD panel is completed.

Front section Array:

1. Thin film 2. Yellow light 3. Etching 4. Peeling

Middle Cell:

5. Alignment film printing 6. Sealant coating 7. Spray spacer 8. Inject liquid crystal 9. Sealing combination 10. Polarizer attachment

Back-end Module Assembly:

11. COG process 12. Flexible circuit board lamination 13. Printed circuit board lamination 14. Backlight module assembly 15. Aging test

Main structural diagram of liquid crystal module (LCM)

Liquid crystal module (LCM) structure (section view)

Liquid crystal module (LCM) constitutes the main components and material applications

1. Polarizing plate: It is mainly used as a grating, allowing only light in one direction to pass through, and can also protect the CF layer and TFT layer.

2. CF layer and TFT layer: one above the other to form an electric field, allowing the liquid crystal to align under this electric field.

3. Alignment (PI) film: The alignment film has directional properties that allow liquid crystals to be regularly arranged on the alignment film.

4. Transparent metal conductive layer (ITO): energizes the upper and lower glass to control the direction of the liquid crystal

5. Frame glue: Just like the walls of a house, it is used to prevent the liquid crystal from contacting the outside world.

6. SPACER: Like the pillars of a house, it is used to support the upper and lower substrates

7. Liquid crystal: Control the arrangement of liquid crystal under different electric fields to obtain the amount of light with different transmittances, thereby achieving the display principle.

8. Backlight module: Only by providing a backlight source can the signal changes of the LCD be displayed.

Three steps in the liquid crystal module (LCM) manufacturing proces.

The first step (JI): Use the machine to laminate the finished LCD panel (Cell), anisotropic conductive glue (ACF), driver IC, flexible circuit board (FPC) and PCB circuit board

Step 2 (MA): Next, assemble the finished product together with the backlight board, light source, and iron frame;

Step 3 (FI): Aging test

After many tests, the above is the “liquid crystal panel (TFT-LCD)” we see.

Liquid crystal module (LCM) manufacturing flow chart

Main Purpose Principles During the Manufacturing Process

According to the TFT-LCD display principle and production requirements, and through the steps and manufacturing flow charts, it is mainly divided into the following two categories:

1. Lamination of driver IC and printed circuit board

2. Application of backlight system, as well as liquid crystal substrate integration and aging test

Driver IC and printed circuit board are pressed together

1. Anisotropic conductive glue (ACF): Anisotropic conductive glue is pressed on the two frames, which allows external electrons to enter the liquid crystal substrate layer and serves as a bridge for electron transmission.

2. Driving IC lamination: The main function of the driving IC is to output the required voltage to each pixel and control the degree of twisting of the liquid crystal molecules. There are two types of drive ICs. The source drive IC located on the The response time of the LCD monitor.

3. The lamination of flexible circuit boards can transmit data signals and serve as a bridge for electronic transmission between external printed circuits and liquid crystal panels. It can be bent, thus becoming a flexible or flexible circuit board.

Backlight system application, and LCD substrate integration

1. Introduction to backlight system types and legends

Liquid crystals do not emit light on their own, so display devices that use liquid crystals as the display medium need to be equipped with an additional backlight system. There are usually three types:

CCFL (Cold Cathode Fluorescent Lamp, cold cathode fluorescent lamp)

LED (Light Emitting Diode, light emitting diode)

EL (electroluminescence electroluminescent panel), OLED (Organic Light Emitting Diode, organic light emitting diode, also known as organic EL), inorganic EL

The side-mounted white LED backlight of Samsung XL2370 is in non-luminous (left) and illuminated (right) states

Regardless of the various placement methods of CCFL backlight or LED backlight, the nature of the light source of the backlight cannot be a surface light source, but a linear light source or a point light source. Therefore, other components are required to evenly distribute the light to the entire surface. This task is performed by the diffusion plate and Diffusion piece to complete.