PCB Technical - Electronic factories need to control each process of PCBA

PCBA is a series of processing processes such as PCB circuit boardmanufacturing, component procurement and inspection, SMT chip processing, plug-in processing, program firing, testing, and aging. The PCBA processing process involves many links, and the electronic processing factory must control the quality of each link in order to produce good products.

1. PCB circuit board manufacturing

After receiving the PCBA order, analyze the Gerber file, pay attention to the relationship between the PCB hole spacing and the board's load-bearing capacity, do not cause bending or breakage, and whether the wiring considers key factors such as high-frequency signal interference and impedance.

2. Procurement and inspection of components

The procurement of components requires strict control of channels, and must be picked up from large traders and original factories, and 100% avoid second-hand materials and fake materials. In addition, a special inspection post for incoming materials is set up, and the following items are strictly inspected to ensure that the components are free of faults.

PCB: Reflow soldering furnace temperature test, no flying leads, whether the vias are blocked or leaking ink, whether the board surface is bent, etc.;

IC: Check whether the silk screen is completely consistent with the BOM, and keep it at constant temperature and humidity;

Other common materials: check silk screen, appearance, power-on measurement, etc. The inspection items are carried out according to the random inspection method, and the ratio is generally 1-3%.

3. SMT patch processing

Solder paste printing and reflow oven temperature control are key points, and it is very important to use laser stencils of good quality and meeting process requirements. According to the requirements of PCB, some steel mesh holes need to be enlarged or reduced, or U-shaped holes are used to make steel mesh according to process requirements. The furnace temperature and speed control of the reflow soldering is very critical to the solder paste infiltration and soldering reliability. It can be controlled in accordance with the normal SOP operation guidelines. In addition, AOI testing needs to be strictly implemented to minimize the defects caused by human factors.

4. DIP plug-in processing

In the plug-in process, the mold design for wave soldering is a key point. How to use molds to maximize the probability of good products after the furnace is a process that PE engineers must continue to practice and summarize experience.

5. Program firing

In the previous DFM report, customers can be suggested to set up some test points on the PCB, the purpose is to test the PCB and PCBA circuit continuity after soldering all components. If you have conditions, you can ask the customer to provide a program, and burn the program into the main control IC through the burner, you can more intuitively test the functional changes brought about by various touch actions, so as to test the function of the entire PCBA Completeness.

6. PCBA board test

For orders with PCBA test requirements, the main test content includes ICT, FCT, aging test, temperature and humidity test, drop test, etc., which can be operated according to the customer's test plan and summarized report data.