Conformal Coating – Conformal coating material is a thin polymeric film which ‘conforms’ to the contours of a printed circuit board to protect the board’s components. Typically applied at 25-250 μm it is applied to electronic circuitry to act as protection against moisture, dust, chemicals, and temperature extremes that, if uncoated (non-protected), could result in damage or failure of the electronics to function.
Reasons for use of Conformal Coating
Conformal coatings are used to protect electronic components from the environmental factors they are exposed to. Examples of these factors include moisture, dust, salt, chemicals, temperature changes and mechanical abrasion. Successful conformal coating will prevent the board from corroding. 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 are breathable, allowing trapped moisture in electronic boards to escape while maintaining protection from contamination. These coatings are not sealants, and prolonged exposure to vapours will cause transmission and degradation to occur. There are typically four classes of conformal coatings: Acrylic, Urethane, Silicone, and Varnish. While each has its own specific physical and chemical properties each are able to perform the following functions: