Flexible PCB board Assembly Basic Knowledge Explanation

Flexible PCB board Assembly Basic Knowledge Explanation

1. Conventional SMD Paste

Features: The accuracy requirements are not high, the number of components is small, the component varieties are mainly resistance capacitors, or there are individual different types.

Key processes: 1. Tibrium paste printing: FPC is positioned on the printing plate by appearance. Generally, a small semi -automatic printing machine is printed, and manual printing can also be used, but the quality of manual printing is worse than the semi -automatic printing.

2. Paste: Generally, manual stickers can be adopted, and individual components with higher location accuracy can also be installed with manual patch machine.

3. Welding: Generally use the re -welding process, and special circumstances can be welded.

2. High -precision paste

Features: There must be a substrate positioning on the FPC. The MARK is marked. The FPC itself must be flat. FPC is difficult to fixed. The consistency in mass production is difficult to guarantee. The requirements for the equipment are high. In addition

Key process: 1.fpc fixation: from printing patch to reflux welding, fix the whole process on the bracket. The brackets used requires that the thermal expansion coefficient must be small. There are two types of fixed method. The paste accuracy is method A when the QFP lead is 0.65mm or more;

Method A: The bracket sleeve is on the positioning template. FPC is fixed on the bracket with a thin high temperature resistant tape, and then separated from the positioning template to print it. The high temperature resistance should be moderate viscosity. After the return welding, it must be easily peeled, and there is no residual rubber agent on the FPC.

Method B: The trustees are customized. For its process requirements, they must be deformed very small after many thermal impacts. There are T -type positioning sales on the bracket board. The height of the sales is slightly higher than that of the FPC.

2. Ten paste printing: Because FPC is loaded on the bracket, the high temperature resistance tape used on the FPC has not consistent with the level of the height as the plate plane. Therefore, the elastic scraper must be used when printing. The ingredients of the tin paste must have a greater impact on the printing effect. The appropriate tin paste must be selected. In addition

3. Paste equipment: First, the printing machine is printed with an optical positioning system, otherwise the welding quality will have a great impact. Second, the FPC is fixed on the bracket, but there will always be some tiny gaps between FPC and the bracket, which is the biggest difference from the PCB substrate. Therefore Impact. Therefore, FPC's post -installation requirements for process control are strict.