Introduction:
With the rapid advancements in PCB manufacturing technology, PCB cleaning processes must continually evolve. Various cleaning techniques offer different advantages and limitations during their application. This paper discusses common issues encountered with these cleaning technologies and provides solutions for addressing them.
1.White Spots:
A common issue in the PCB cleaning process is the appearance of white spots on the surface of components after cleaning and drying. These white spots are caused by residue films left behind during the cleaning process. The main reason for their formation is that the dissolved residue from the cleaning process is not completely removed due to its low solubility. As the components dry, non-ionic material crystals form, resulting in visible white spots.
To solve this issue, using cleaning solutions with a higher concentration can enhance the cleanliness of the process, reduce the need for repeated cleaning, improve cleaning efficiency, and lower labor and equipment costs.
2.Peeling of Paint Layers from Components:
Some components are coated with paint, and in previous testing phases, components were painted or laser-marked. The cleaning parameters and materials used in the original process may not be suitable for these types of components. To address this, a small amount of preservatives should be added to the cleaning solution to neutralize the corrosive effects of alkaline cleaners. Specific cleaning tests should be conducted for components with painted surfaces to determine the right preservative concentration, cleaning solution composition, cleaning time, and temperature adjustments.
3.Component Identification Marks Fading:
Another issue during cleaning is the fading or removal of identification marks on components. Typically, these marks are made with ink, which has poor solvent resistance. If changing the identification method or the component supplier is not an option, process adjustments are required. For components of the same type but from different suppliers or batches, some may retain their marks better than others during cleaning. This issue can be traced back to the supplier’s ink quality. However, cleaning tests have shown that the fading of component marks does not affect the functionality of the components. As such, these marks can be replaced by product files or device location numbers for traceability purposes.
Conclusion:
This paper highlights common issues faced during the PCB cleaning process. If you have suggestions for solving these problems or other issues not addressed here, we encourage you to share your insights with us at WellCircuits!
If you have any questions about PCB or PCBA, feel free to contact me at info@wellcircuits.com.
