Coated, Potted or Sealed: Supplies for Harsh Environments

“Rugged” is not a specification. Before choosing protection, be specific about what the environment actually does to the electronics — the answers point at different measures.

Match the measure to the threat

• Condensation and humidity. The risk is moisture bridging tracks. Conformal coating is the usual answer: a thin lacquer over the assembly that keeps films of moisture off the copper.
• Dust and airborne fibres. A sealed or coated unit stops contamination settling and tracking, and it removes the filter-cleaning schedule that a fanned supply otherwise needs.
• Vibration and shock. Here coating helps little. Potting — filling the case with resin — supports heavy components and stops lead fatigue, and it improves heat transfer into the case as a bonus.
• Salt, solvents and corrosive atmospheres. These need a fully sealed unit; a coating is not a chemical barrier.
• Water ingress. That is an IP rating question about the enclosure, and it is separate from everything above.

The trade-offs to expect

Potting adds weight and makes repair impossible, so a potted unit is a replace-not-fix item. Sealed units cannot use forced air, so they are generally derated or physically larger for the same output. Both cost more than a standard supply, which is why matching the measure to the actual threat matters — over-specifying here is expensive.

Do not overlook temperature cycling

Equipment that is switched off overnight in an unheated space breathes as it cools, drawing damp air in. That is often more damaging than continuous humidity, and it is an argument for leaving equipment powered.

Tell us the environment and we will help you specify only the protection you need.