Safely Cleaning PCBs -- Most Important Considerations
Cleaning printed circuit boards is always fraught with some risk; consequently, you need to weigh the need for such cleaning with the possibility of damaging the board. Naturally, if you suspect that the messiness of the PCB may be the reason behind or may lead to malfunction, then, by all means, clean away.
If you must clean a PCB, then you need to follow certain precautions. Other considerations that should apply include:
- What type of debris are you dealing with?
The easiest PCB debris to get rid of is, of course, free-flowing dust—especially if you remove socketed components from the board before proceeding. Dust and particles can easily be removed with pressured air (preferably from a low-power vacuum cleaner) and a gentle brush. Grime, on the other hand, presents a more serious, albeit manageable problem. Removal thereof (especially if wax or oil is involved) may require some scrubbing and, possibly, the use of water and liquid cleaners.
- Does the board have components that may be especially vulnerable to liquids?
Things like cardboard-contained components, carbon film/open-frame potentiometers and older-version, water-vulnerable crystals may be especially vulnerable to liquids (including water); that goes for paper stickers. Some such items might be de-soldered/removed to make the cleaning process more feasible/easier. By all means, properly dry out the board after such cleanings—possibly with the use of the oven set at a low temperature (i.e., 170 degrees).
- Should you consider using professional cleaning supplies, equipment and techniques?
In addition to special cleaning agents (i.e., “Brasso”), there are special techniques/services that you can employ, including media blasting, ultrasonic cleaning, and media tumbling. You can also hire people who specialize in such services or avail yourself of the literature on PCB cleaning fundamentals.
Conclusion: Dealing with unclean PCBs is not just a matter of aesthetics. Debris and gunk in PCBs can hamper performance and, in the long run, lead to malfunction. By following strict protocols and cleaning PCBs only when absolutely necessary, though, you can avoid unnecessary, possibly expensive trouble. If the board is tainted with left-over solder flux, then you may use either flux remover or rubbing or anhydrous alcohol, making sure to dry the surface with lint-free towels/tissue.