PCBA Tech - How to control PCBA processing?

How to control PCBA processing?
The PCBA processing process involves many links. To produce a good product, the quality of each link must be controlled. Generally,PCBA is composed of a series of processes such as PCB circuit board manufacturing, component procurement and inspection, SMT chip processing, plug-in processing, program firing, testing, and aging. 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 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 of Components
The procurement of components requires strict channel control, purchase from major merchants and original factories, and 100% eliminate second-hand materials and counterfeit materials. In addition, set up a special incoming inspection post to strictly inspect the following items to ensure that there are no defects in the parts.

PCB: Reflow oven temperature test, no flying wire, whether the hole is blocked or leaking ink, whether the board surface is bent, etc.
IC: Check whether the screen is completely consistent with the BOM, and maintain constant temperature and humidity;

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

3. SMT assembly processing

The temperature control of solder paste printing and reflow oven is the key. The quality and process requirements of laser stencils are very important. According to the requirements of PCB, some need to increase or decrease steel mesh, or use u-shaped holes to make steel mesh according to process requirements. The furnace temperature and speed control of reflow soldering is very important to the solder paste infiltration and soldering reliability, and can be controlled according to the normal SOP operation guide. In addition, AOI testing must be strictly implemented to minimize the adverse effects caused by human factors
4. Dip plug processing
In the process of plug-in assembly, the mold design of wave soldering is the key. How to use the mold to maximize the good products after the furnace, this is a process that PE engineers must continue to practice and sum up experience

5. Program burning

In the previous DFM report, customers can suggest to set up some test points (test points) on the PCB, the purpose is to test the continuity of the PCB and PCBA circuit after all components are soldered. If you have the conditions, you can ask the customer to provide a program, the program is mainly through the burner control integrated circuit (such as ST-LINK J-LINK, etc.), you can more intuitively test the various touch behavior functions that change the whole The integrity of the PCBA test function.

6. PCBA board test
For orders with PCBA test requirements, the main test content includes ICT (circuit test), FCT (functional test), Burn In test (aging test), temperature and humidity test, drop test, etc., operate according to the customer's test plan and summarize the report data .