Silicone conformal coating is becoming an increasingly popular choice for conformal coating applications. Because of its high temperature capabilities, moisture protection, and ease of application/rework, people are strongly considering silicone coatings for their projects.
Most typical silicone coatings have continuous operating temperature ratings of 200ºC. This is far higher than parylene (80ºC) and acrylics (125ºC). Some silicone coatings are rated as high as 600ºC for ultra high temperature applications. We have seen a great deal of use for silicones in the automotive industry, where temperatures can get upwards of 175ºC in the engine compartment.
An additional benefit of silicone conformal coating is its excellent moisture protection. Silicones have been used in cases where there were extreme temperature differences, which resulted in excessive moisture. Other conformal coatings failed within hours or days, while silicone, especially when applied thickly, has been proven to succeed.
Silicone conformal coatings are among the easiest to apply and re-work. Silicone coatings are typically low on solvents, ensuring a smooth coat that cures very quickly (about one hour at room temperature). Silicones are quite flexible and soft, having a relatively weak resistance to solvents. For assemblies that will require work after coating, this is critical because it will keep costs and time down.