PCBA manufacturing process involves the link more, be sure to control the quality of every link to produce good products, general of PCBA consists of: PCB manufacturing, components procurement and inspection, SMT processing, plug-in processing, program fire, testing, aging, and a series of process, we carefully explain every link below need to be aware of.
1. PCB circuit board manufacturing
After receiving the PCBA order, analyze the Gerber file, pay attention to the relationship between the hole spacing of PCB and the bearing capacity of the plate, do not cause bending or fracture, and whether the wiring takes into account the key factors such as high-frequency signal interference and impedance.
2. Procurement and inspection of components
Procurement of components should be strictly controlled channels, must be picked up from large traders and original factories, 100% to avoid second-hand materials and fake materials. In addition, special inspection posts will be set up to carry out strict inspection of the following items to ensure the components are fault-free.
PCB: reflow furnace temperature test, no fly line, whether the hole is blocked or leaking ink, whether the board is bent, etc
IC: Check whether the screen printing is completely consistent with BOM, and do constant temperature and humidity preservation
Other common materials: screen printing, appearance, electrified test value, etc. Inspection items shall be carried out according to sampling inspection method, the proportion is generally 1-3%
3. SMT Assembly processing
Solder paste printing and reflow 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, part of the mesh should be enlarged or shrunk, or U-shaped hole should be used to make the mesh according to the process requirements. Furnace temperature and speed control for reflow soldering is critical for solder paste wetting and welding reliability, and can be controlled in accordance with normal SOP operating guidelines. In addition, STRICT IMPLEMENTATION of AOI testing is needed to minimize the adverse effects caused by human factors.
4, plug-in processing
In the plug-in process, the die design is the key point for over wave soldering. How to use molds to maximize the probability of good products after passing through the furnace is a process PE engineers must constantly practice and summarize experience.
5. Process firing
In the early DFM report, the customer can be advised to set some Test Points on the PCB for the purpose of testing the PCBA circuit conductivity after the PCB and all components have been welded. If conditions permit, the customer provider can be required to burn the program into the main control IC through a burning device (such as ST-Link and J-Link), so as to test the functional changes brought by various touch actions more intuitively, so as to verify the functional integrity of the whole PCBA.
6. PCBA board test
For orders with PCBA Test requirements, the main Test contents include ICT (In Circuit Test), FCT (Function Test), Burn In Test, temperature and humidity Test, drop Test, etc., which can be operated and reported according to the customer's Test plan.
