The PCBA manufacturing process is a very complicated process. The entire PCBA process seems to be different from PCB in only one word. In fact, it has changed a lot. PCBA has a series of PCB-based back-end processes, such as solder paste printing, SPI inspection, SMT processing, reflow soldering, DIP post soldering, wave soldering/selective wave soldering, PCBA first piece inspection, etc. The craftsmanship does not come with PCB.
However, because all subsequent processes are based on the PCB board, the quality of the PCB determines the quality of the entire PCBA. So what aspects of PCB have an impact on PCBA? Next, Shenzhen Viasion Electronics, a PCBA processing manufacturer in Shenzhen, will share with you.
1. The board is dirty
Dirty board surface is mainly caused by high solid content of flux, too much coating amount, too high or too low preheating temperature, or too dirty conveyor belt PCB clamping jaws, excessive oxides and tin dross in the tin bath.
The main solution is to select the appropriate flux; control the amount of flux applied; control the preheating temperature; check the cleaning effect of the automatic PCB jaw cleaning and take measures; timely clean the oxide and tin dross on the surface of the tin bath.
2. White residue
The white residue is often called hoarfrost. Although it does not affect the surface insulation resistance, the customer does not accept it.
Solution: first use flux and then solvent to clean; if it cannot be cleaned, it may be due to the aging of the flux, or it may be exposed to the air to absorb water vapor, or it may be due to the high moisture content in the cleaning agent (solvent), or The flux does not match the cleaning agent, the supplier should be asked to help solve or replace the flux cleaning agent.
3. PCB deformation
PCB deformation is mainly caused by excessive PCB quality or uneven component layout.
When designing the PCB, try to make the components evenly distributed. Design a support belt in the middle of the large-size PCB (the design width of the non-layout component area is 2~3mm); or use a mass balance tool to press the sparse components on the PCB during the soldering process to achieve mass balance.