The PCBA processing process involves many links, and it is necessary to control the quality of each link to produce a good product. The general PCBA is composed of: PCB circuit board manufacturing, component procurement and inspection, SMT patch processing, plug-in processing, A series of processes such as program burning, testing, aging, etc. Below we carefully explain the points that need to be paid attention to in each link.
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 bearing capacity of the board, do not cause bending or breaking, and whether the wiring considers key factors such as high-frequency signal interference and impedance.
2. Component procurement and inspection
The procurement of components requires strict control of channels, and it is necessary to pick up goods from large traders and original factories, and 100% avoid second-hand materials and fake materials. In addition, set up special incoming inspection positions, strictly check the following items to ensure that the components are not faulty.
PCB: temperature test of reflow soldering furnace, prohibition of flying wire, whether the hole is blocked or ink leakage, whether the board surface is bent, etc.;
IC: Check whether the silk screen is completely consistent with BOM, and keep it at constant temperature and humidity;
Other common materials: check the silk screen, appearance, power-on measurement, etc. The inspection items are carried out according to the random inspection method, and the proportion is generally 1-3%.
3. SMT Assembly processing
Solder paste printing and reflow soldering furnace temperature control are the key points. It is very important to use laser stencil with good quality and meet the process requirements. According to the requirements of PCB, some need to increase or decrease the steel mesh hole, or use U-shaped hole, according to the process requirements to make steel mesh. The furnace temperature and speed control of reflow soldering is critical to solder paste infiltration and soldering reliability, and can be controlled according to normal SOP operation guidelines. In addition, AOI testing needs to be strictly implemented to minimize the adverse effects caused by human factors.
4. DIP plug-in processing
In the plug-in process, the mold design for wave soldering is the key point. How to use the mold can maximize the probability of providing good products after the furnace, which is a process that PE engineers must constantly practice and sum up experience.
5. Program burning
In the previous DFM report, customers can be suggested to set some test points on the PCB (Test Points), the purpose is to test the PCB and PCBA circuit continuity after soldering all components. If you have the conditions, you can ask the customer to provide a program, burn the program into the main control IC through a burner (such as ST-LINK, J-LINK, etc.), you can more intuitively test the various touch actions brought by 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 plan operation And summarize the report data.
