High-Performance Silicone Conformal Coating

Printed circuit boards (PCBs) are used in many types of electronic devices and in all types of environments. A conformal coating is used for protection against environmental exposure (moisture, temperature variations, dust/dirt and mechanical forces such as vibrations) to extend the operating life of the device. A silicone conformal coating will do just that, even in harsh conditions.

Why use silicone conformal coatings?

• Silicones are very temperature resistant and function well in a very broad range of operating temperature. Where organic types of coatings (such as acrylics or urethanes) tend to break down at higher temperatures and become very brittle at low temperatures, silicones maintain their flexibility and strength both at very low and very high temperatures. Operating temperatures between -60 ˚C and 200 ˚C are not uncommon for silicones.
• Silicone based conformal coatings are available in many forms and can vary in terms of viscosity, hardness and mechanical properties to best suit your application.
• Silicone is a flexible material and will protect PCBs with even the most sensitive components by providing stress relief.
• Silicones are hydrophobic which means that they offer a high resistance to moisture.
• Processability. Silicones are usually easy to process.
• Silicone coatings from Nusil have been shown to perform very well in ageing tests. Silicones out-perform urethanes and show minimal yellowing and cracking.
• High dielectric strength and a low dissipation factor.

Key characteristics of silicone based conformal coatings

• Silicone based conformal coatings are normally 1-component systems which means easy dispensing and handling.
• They cure at room temperature when exposed to atmospheric moisture.
• The curing starts from the outside in which means that coated PCBs can quickly be handled without mess shortly after coating, even though full curing is achieved after 24 hours.
• Viscosity can vary greatly depending on the thickness needed. For example, tall components that need to be covered require a higher viscosity. Most common is however to use dip or spraying techniques when applying the silicone conformal coating. Hence, a low viscosity is ideal.
• Non-corrosive (silicone conformal coatings are usually oxime, amine or alkoxy curing).

Suggested products

Silicone conformal coatings from Nusil are one-part, flowable and room temperature curing (RTV). They are designed to be used as coatings on both rigid and flexible PCBs and provide long-term protection reliable regardless of the environment in which the PCB is operating.

Nusil R-1008-0

Nusil R-1099

Nusil R-1077