Conformal coating

Conformal coating is a protective, breathable coating of thin polymeric film applied to printed circuit boards (PCBs). Conformal coatings are typically applied at 25–250 μm to the electronic circuitry and provide protection against moisture and other harsher conditions.

Coatings can be applied in a number of ways, including brushing, spraying, dispensing, and dip coating. A number of materials can be used as conformal coatings, such as acrylics, silicones, urethanes and parylene. Each has its own characteristics for different purposes. Many circuit board assembly firms can coat assemblies with a layer of transparent conformal coating, which is used as an alternative to potting.

Conformal coatings are used to protect electronic components from the environmental factors they are exposed to. More recently, conformal coatings are being used to reduce the formation of whiskers, and can also prevent current bleed between closely positioned components.

Conformal coatings allow trapped moisture in electronic boards to escape while maintaining protection from contamination. These coatings are not sealants, and prolonged exposure to vapors will cause transmission and degradation to occur. There are typically four classes of conformal coatings: acrylic, urethane, silicone, and varnish. All of which allows for a closer conductor spacing.