Because printed circuit boards are small, fragile wafers, thin layers of acrylic, polyurethane or silicone coatings are applied to them to provide dielectric insulation and protection from adverse environmental conditions.
Acrylic conformal coatings. Sufficiently flexible, they protect the surface well against moisture and dust. Acrylic is vulnerable to some solvents and chemicals, making it ineffective against chemical threats.
Urethane conformal coatings. Polyurethane has abrasion resistance, flexibility, electrical insulation properties and chemical resistance. Applications include automotive, industrial and consumer electronics, medical devices, aerospace and defense electronics. Cures when exposed to heat or moisture.
Silicone conformal coatings. Silicone-based conformal coatings are the preferred choice when the PCB is exposed to temperature extremes from -40 °C to 160 °C. Silicone conformal coatings cure when exposed to heat, moisture and UV.
UV-cured protective coatings. The selected material is applied by cross curtain, spraying, dispensing valves or brush under yellow light. The UV light is used to fix the conformal coating to the board. UV-cured protective coatings provide abrasion and temperature resistance.