A conformal coating is a thin, protective coating for PCBs and other electronic components providing insulation and protection from external and environmental conditions. Available in a variety of formulas, the most common conformal coatings are made from acrylic, epoxy, silicone or urethane. The coating can be removed easily with most common solvents, or specialist solvents can be used to remove and rework a conformal coating. At RS, our range features products from industry-leading brands such as Ambersil, Chemtronics, Electrolube, MG Chemicals and RS PRO.

Why use a conformal coating?

A conformal coating provides protection from external conditions and contaminants, such as moisture, sea salt, chemicals and extreme temperatures. This protection extends the working life of the PCB, as well as allowing for higher voltages and closer track spacing on the PCB.

Conformal coatings are used in many types of applications where high performance and reliability are needed. These include military, automotive, marine and green energy to domestic and mobile electronic industries.

How are conformal coatings applied?

Conforming coatings are applied in low volume applications by brushing the components with the coating material. For low to medium volume applications, the coating can be sprayed onto the PCB using an aerosol or dedicated spray booth, providing excellent tip coverage to the components. High volume applications often use a dipping method. Masking is an important part of this coating process and must be applied perfectly to protect the PCB circuit board when using this coating process. A component can be reworked after a conformal coating is applied.

When using a conformal coating, the viscosity and thickness of the coating is highly important as it can affect PCB performance. Viscosity of the conformal coating must be monitored as part of the process.

What are the different types of conformal coating?

• Silicone coatings give great protection in a range of temperatures, good chemical resistance, flexibility and resistant to sea salt.
• Acrylic coatings, easy to use and remove, provide fair elasticity, abrasion resistant and have high dielectric strength.
• Polyurethane/urethane coatings have excellent moisture and chemical resistance and are abrasion-resistant.
• Epoxy coatings give good humidity resistance, high abrasion and chemical resistance.