PCBA process control and quality control points

1, PCB circuit board manufacturing
After receiving an order from PCBA, analyze the Gerber file, pay attention to the relationship between the hole spacing of the PCB and the bearing capacity of the board, and do not cause bending or breaking. Whether the wiring takes into account key factors such as high-frequency signal interference and impedance.

 

2, component procurement and inspection
The procurement of components and components requires strict control of the channels. It is necessary to take delivery of goods from large-scale traders and the original factory, and 100% to avoid second-hand materials and counterfeit materials. In addition, special incoming inspection positions are set up, and the following items are strictly inspected to ensure that the components are not faulty.

PCB: reflow oven temperature test, no fly line, whether the hole is blocked or leaked ink, whether the board surface is bent, etc.
IC: Check whether the silk screen and BOM are exactly the same, and do constant temperature and humidity preservation
Other common materials: check the screen printing, appearance, power measurement, etc., check the project according to the sampling method, the proportion is generally 1-3%

 

3, SMT Assembly processing
Solder paste printing and reflow oven temperature control are the key points. It is very important to use quality and meet the process requirements. According to the requirements of the PCB, some steel meshes need to be enlarged or reduced, or U-shaped holes are used to make stencils according to the process requirements. Reflow furnace temperature and speed control are critical for solder paste wetting and soldering reliability. Follow normal SOP operating guidelines for control. In addition, strict AOI testing is required to minimize human-induced adverse effects.

 

4, plug processing
In the plug-in process, mold design for over-wave soldering is a key point. How to use the mold can maximize the probability of providing good products after the furnace, which is the process that PE engineers must constantly practice and experience.

 

5, program firing
In the previous DFM report, customers could be advised to set up some test points on the PCB in order to test the PCB and PCBA circuit continuity after all components are soldered. If there are conditions, you can request the customer to provide a program to burn the program into the main control IC through a writer (such as ST-LINK, J-LINK, etc.), so that the various touch actions can be more intuitively tested. Functional changes to test 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 In Test (aging test), temperature and humidity test, drop test, etc., according to the customer's test program And summarize the report data.