In the production of LCD panels, PCB circuit boards occupy an extremely important position, so PCB circuit board typing what exactly used to make him occupy such a position in the production of LCD panels?

1. High Density

In order to adapt to the development of fine pitch and multi-lead technology of surface mount components, the PCB wiring density gradually increased. At present, the lead spacing of 0.762mm > 0.635mm → 0.508 mm + 0.381mm > 0.305mm PCB components line width and line spacing has been reduced to 0.15-0.1 mm, multi-lead, fine-pitch components, the application of the PCB installation density has been greatly improved. Compared with the traditional plug-in printed board, surface mount printed board area reduced by 60%, weight reduced by 80%, circuit logic density increased by more than 5 times.

2. Small Aperture

In surface mount PCB, most of the metallization holes are no longer used to insert fixed components, but to realize the through connection of each layer of the circuit. With the increase in component assembly density, the wiring density on the board greatly increased, the hole diameter is also increasingly reduced. The diameter of metallized through-hole is generally 0.60 ~ 0.30mm, and to 0.30 ~ 0.10 mm direction.

3. Many Levels

With the increasing integration of electronic components and assembly density, miniaturization and ultra-miniaturization of electronic components, PCB boards are not only suitable for single-layer and double-sided, but also widely used in wiring density of multi-layer board, there are 68 layers and 4 layers in LCD module.

4. PCB Circuit Boards Have Excellent Transmission Characteristics

With the development of high-frequency working circuit, the PCB characteristic impedance, surface insulation resistance, dielectric constant, dielectric loss and other high-frequency performance has put forward higher requirements for the PCB substrate.

5. High Flatness and Smoothness

As the components are mounted directly on the printed circuit board, the board surface requires a higher degree of flatness and smoothness. Rough surface of fiber cloth, bumpy texture will lead to poor surface mount component fit, poor soldering, and even can not come off. As the PCB warpage not only directly affects the automatic surface mount and welding positioning, but also causes chip components and points to produce tiny cracks due to deformation, thus leading to circuit failure, so the general requirement is that the PCB warpage before static welding should be allowed to be less than 0.3%, and requires the selection of good dimensional stability, small warpage and excellent overall performance of the substrate in the process of material selection, assembly and manufacturing.

6. Good Stability

In the component installation, the thermal expansion of the PCB produces stress on the electrodes of the component, resulting in component damage or solder joint failure. Therefore, the coefficient of thermal expansion of the substrate is one of the important factors that must be considered in PCB design and material selection. The expansion coefficient of the PCB is required to be as small as possible, and the expansion coefficient of components and PCBs should be matched. Printed circuit board substrate to epoxy resin or epoxy phenolic resin as the adhesive, cotton fiber cloth, paper and glass fiber cloth as a reinforcing material, the surface covered with electrolytic copper foil and pressed. LCD display modules use 0.5 mm, 1.0 mm, 1.2 mm, 1.6 mm, 2.0 mm and other printed circuit board thickness.