circuit board cleaning

  • Is Water Harmful to Electronic Components?

    hose-spraying-waterMany experts in the electronics assembly world will cringe when they hear about a manufacturer hand-washing their boards with soap and (gasp!) water. The first point to bring up here is that boards should never need to be washed. This is a clear indication that you are somehow bringing dirt into the process, whether through alcohol, brushes, or something else the boards are coming in contact with.

    Know Your Water Grade

    There are three grades of water that you can use to clean the boards; tap water, distilled water, and deionized (DI) water. For this type of precision cleaning you should never use tap or distilled water, which themselves contain contaminants that can affect your boards. If you must clean your boards with water, the only choice is deionized water.

    Deionized water is measured by the water’s resistance to electric current. 50kOHM is standard and can be purchased easily and at a relatively low cost. 1 megaohm is really the minimum required for this type of precision cleaning. In high-precision manufacturing, such as semiconductors, 20 megaohms is the industry standard. Obviously cost and availability are both big factors. As you increase the pureness of your water, it also becomes more difficult to handle.

    One option is a sealed, closed-loop system which purifies the water, performs the cleaning task, and then recycles the water. However, this type of system is costly and can result in a slow through-put. Given these restrictions when using water in the cleaning process, more and more manufacturers are switching to cleaning with solvents. The ideal solvent is strong enough to remove the contamination, while still mild enough to not damage any components on the board.

    GoKimco has a complete line of solvents, ideal for finding this healthy balance for cleaning your boards.

  • 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/tissueThinkingEngineer

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