Coating is not a universal upgrade. It is a targeted answer to a specific environment, and applying it without that environment in mind buys cost rather than reliability.
Conformal coating protects an assembly against moisture, condensation, salt and airborne contamination. Where those are present — marine, outdoor, unheated buildings, process environments — it is cheap insurance. Where they are not, it adds cost, complicates rework and can trap contamination it was supposed to exclude.
The decision should follow the environment, not the customer's comfort. Ask where the unit lives, whether it sees condensation cycles, whether the enclosure breathes, and what a failure costs. A bridge-side cabinet and an office-floor controller are different products even when the board is identical.
Application details matter more than the choice of material. Masking connectors and test points, controlling thickness, curing properly and inspecting under UV are what separate a coating that works from a cosmetic layer. A poorly masked board is worse than an uncoated one because it fails inspection and rework at the same time.
And plan for repair. A coated assembly is harder to rework, so the repair route has to be defined at design time: which areas may be reworked, with what process, and how the coating is restored. Deciding that during a field campaign is the expensive way to learn it.
— GANI Contract Manufacturing engineering team