What is a conformal coating?

What is a conformal coating?

Co-Authors and contributors
  • Dr Lee Hitchens, Nexus
  • Karl Hardcastle, SCH Technologies

A conformal coating is a protective, thin, non-conductive film of material that is applied to the printed circuit board assembly after the majority of the circuit board assembly productions processes are completed and generally before assembly into the final product.

Typically applied at 25-75μm, the conformal coating itself is a thin plastic protective film“ conforming” to the surface of a printed circuit board.

This conformal coating creates a barrier between the contaminants and the circuit board.

This coating has insulation properties and this protects the electronics.

When applied, the conformal coating is clearly visible as a clear and shiny lacquer on the surface of the printed circuit board. Under UV light the coating can fluoresce brightly due to the additives.

Some coatings are hard, while others have a slightly rubbery texture.

Before application, the conformal coating is generally in a liquid state. These liquid coatings can be of several different generic resins including acrylics, polyurethanes, silicones, epoxy’s or combinations of the resins.

There are other conformal coating materials available that are different to the traditional liquid coatings.

These alternative coatings include vapour deposited coatings, such as Parylene, and fluorochemical materials, which are surface modifiers.

Most coatings include a marker that appears greenish white when view under UV light.

This marker enables easy inspection of the coating thoroughness checking during production.


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