Conformal coatings for PCB protection, silicone and acrylic

ACC Silicones conformal coating application sheet

Protecting the PCB board in critical applications which are exposed to harsh environmental working conditions is essential if product failure is to be avoided.  A conformal coating is normally applied as a thin layer across the surface of the board, covering all components and delicate wiring.

For any coating to be effective it must maintain good adhesion to all the component substrates, be unaffected by changes in operational temperature and be resistant to any contaminants, such as moisture and chemicals.  Its ability to flow around, under and over the components without leaving areas exposed to the atmosphere especially on sharp edges, is also important.

Most conformal coatings are clear and many formulations have a UV indicator to enable easy visual quality control inspection under an ultra violet light source.  Cure systems vary and include air drying, heat cured and UV cured.

Coating Types

Silicone

These 1-component silicone coatings can be formulated using either addition cure technology for heat cured and condensation cure for materials that cure at room temperature (RTV).  Very fast cycle times can be achieved using a heat cured coating in conjunction with a curing oven.  Their ability to withstand a very wide operating temperature range makes them suitable for aerospace and automotive applications. Silicone also has a natural ability to protect against moisture ingress.

Key Features

• Wide operating temperature range (-55 ºC to + 200 ºC)
• Room temperature or heat cure
• Low viscosity
• 100% solids (no harmful solvents)
• Excellent adhesion to many substrates
• Low odour
• RoHS complian