Preprocessing of FPC

Preprocessing of FPC

FPC board is relatively soft, factory is generally not vacuum packaging, easy to absorb moisture in the process of transportation and storage, need to be pre-baked before SMT line, the water will slowly forced out. Otherwise, under the high temperature impact of reflow welding, the water absorbed by FPC will be rapidly gasified into water vapor, which will easily lead to FPC stratification and foaming.

Special plate production

According to the CAD file of the circuit board, the hole positioning data of FPC is read to manufacture the high-precision FPC positioning template and special plate, so that the diameter of the positioning pin on the positioning template matches the positioning hole on the plate and the diameter of the positioning hole on the FPC. Many FPC are not of the same thickness due to the protection of some lines or design reasons. Some places are thick while others are thin, and some are reinforced with metal plates. Therefore, the interface between the loading plate and FPC needs to be processed, polished and dug according to the actual situation. The material of the carrier plate requires light weight, high strength, less heat absorption, fast heat dissipation, and small warping deformation after many thermal shocks. Commonly used plate materials are synthetic stone, aluminum plate, silicone plate, special high temperature resistance magnetized steel plate.

1. FPC fixing

Prior to SMT, the FPC needs to be precisely fixed to the board. It is particularly important to note that the time between printing, mounting, and welding is as short as possible after the FPC is fixed to the board. There are two kinds of plate with and without locating pin.

2. Solder paste printing of FPC

FPC of solder paste composition is no special requirements, the size of the tin ball particles and metal content, etc will be subject to have FPC on fine pitch IC, but FPC high performance requirements of the solder paste printing, solder paste should be has good thixotropy, solder paste should be able to easily print demoulding and can firmly adhere to the surface of FPC, there will be no mold release bad block stencil hole leakage or produce the bad such as collapse after printing.

3. FPC patch

4. Reflow welding of FPC

5.FPC inspection, testing and sub-board