When designing a PCB for humid environments with possible condensation, conformal coating is often used for protection. However, some areas (like connectors and pogo-pin contacts) must be masked and left uncoated. How should these exposed areas be handled to prevent corrosion or reliability issues? Is using finishes like ENIG or gold-plated contacts sufficient, or are there better design or protection strategies?
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There are nano coatings that are supposed to allow coverage to areas that normal conformal coatings cannot be applied to. I have not tested them myself but they look like a potential solution to many difficult assembly situations.
Example: https://nanoflowx.com/
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Minimizing exposed bare metal is the simplest starting point. Putting connectors in recessed/sheltered spots or using sealed connectors means the conformal coating isn’t your only line of defense. Beyond that, it’s usually condensation plus contamination together that drives corrosion and not moisture alone. So thorough cleaning after assembly can be just as important as whatever coating or finish you choose.
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For exposed contact areas, connector mating cycles also matter. Thin gold flash may resist corrosion initially, but repeated insertion can wear through it and expose the underlying metal. For humid or condensing environments, hard gold plating on high-cycle contacts is usually more reliable than relying only on standard PCB surface finishes like ENIG.
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Interesting point about nano coatings. I’ve mostly seen traditional acrylic/silicone conformal coatings used.
Good point about contamination. It’s easy to focus only on the coating itself and overlook how important cleaning and enclosure design are for long-term reliability.
That makes sense. Connector wear over repeated mating cycles is something that’s probably easy to underestimate in humid environments.