PCB News - Related knowledge about FPC in mobile phone PCB design

Why use FPC?

The main board of the mobile phone and the small board of a certain circuit module are electrically connected through the FPC. For example, camera FPC, screen FPC, TP FPC,

Audio small board FPC, etc.; general button PFC mainly includes power button, volume button, and other function buttons.

1) Layer selection: generally 2-layer PCB board is the main choice.

2) Material selection: In order to ensure the bending performance, it is recommended to choose 0.5mil/0.5oz single-sided substrate, rolled copper (RA); Cover layer (cover film) choose 0.5mil.

3) Bend area line:

a) There must be no through holes in the part to be bent;

b) Add protective copper wires on the two sides of the line. If there is not enough space, choose to add protective copper wires at the inner corners of the bent part. c) The connecting part of the line needs to be designed as an arc.

4) Bending area (air gap): The bending area needs to be layered, and the glue is removed to facilitate the effect of stress dispersion. The larger the bending area, the better without affecting the assembly.

5) Shielding layer: At present, the shielding layer of mobile phone PCB design generally uses silver paste and copper foil.

a) The use of silver paste shielding layer reduces the actual number of active layers, facilitates assembly, simple process and low cost. However, because the silver paste is a mixture, the resistance is relatively high, about 1 ohm. Therefore, it is not possible to directly design the silver paste layer as the ground wire.

b) Copper foil shielding layer, the number of active layers is increased by two, the cost increases, but the resistance is lower, and it can be directly designed as a ground wire.

c) Silver foil shielding layer, the cost is too high.

The above is the introduction of FPC related knowledge in mobile phone PCB design. Ipcb also provides PCB manufacturers and PCB manufacturing technology.