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The main points of PCBA process control and quality control
2021-10-02
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Author:Frank

The main points of PCBA process control and quality control
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

pcb board

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

3. SMT Assembly 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. 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 (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 a burner (such as ST-LINK, J-LINK, etc.), and you can more intuitively test the effects of various touch actions. Functional changes to verify the functional integrity of the entire PCBA

6. PCBA board test
For orders with PCBA test requirements, the main test content includes ICT (In Circuit Test), FCT (Function Test), Burn InTest (aging test), temperature and humidity test, drop test, etc., according to the customer's test plan operation and Just summarize the report data.