With the continuous development of electronic technology, people’s requirements for product design are getting higher and higher, engineering wiring is becoming more and more precise, and electronic component application packaging is getting smaller and smaller. Product quality control has become the biggest challenge for PCB assembly. From PCB circuit board manufacturing, component procurement and inspection, SMT chip processing, plug-in processing, program firing, testing, aging and other processing to the final product shipment, each step is very important, and any details in the assembly process will determine the quality of the final product.
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
Use approved manufacturers and distribution channels with traceability, incoming acceptance checks and an agreed policy for substitutions. Supplier size alone does not establish authenticity or component suitability. 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 failure.
- 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 the silk screen, appearance, power-on measurement, etc. Define incoming inspection and sampling from part risk, supplier history and the agreed acceptance plan; a fixed 1–3% sample is not a universal requirement.
3. SMT Patch Processing
Solder paste printing and reflow oven temperature control are key points. 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. Through-Hole Assembly (THT)
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. Firmware Programming
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, burn the program into the main control IC through the burner, and test the function changes brought about by various touch actions more intuitively, so as to test the function of the entire PCBA completeness.
6. PCBA Board Test
Agree the test plan before the build: unpowered shorts checks, any ICT or flying-probe coverage, firmware identification, controlled power-up, functional limits and traceable results. Environmental, burn-in and drop tests apply when specified for the product; they are not automatic steps for every assembly. See functional testing for the fixture and acceptance information needed.
PHILIFAST provides one-stop PCB manufacturing and assembly services, complete production process, and focus on quality control.