IPC-2221 4.5.2.1 Conformal Coating Types and Thickness Conformal coating may be any one of the types indicated. The thickness of the conformal coating shall be as follows for the type specified, when measured on a flat unencumbered surface:

IPC-2221 4.5.2.1 Conformal Coating Types and Thickness Type AR - Acrylic Resin 0.03-0.13 mm Type ER - Epoxy Resin 0.03-0.13 mm Type UR - Urethane Resin 0.03-0.13 mm Type SR - Silicone Resin 0.05-0.21 mm Type XY - Paraxylylene Resin 0.01-0.05 mm

IPC-2221 4.5.2.1 Conformal Coating Types and Thickness There are three primary chemical categories in use for conformal coating materials: silicone elastomers, organics, and parylene. All three types provide various levels of protection from solvents, moisture, corrosion, arcing, and other environmental factors that can jeopardize are circuits operation performance.

IPC-2221 4.5.2.1 Conformal Coating Types and Thickness Many surface mount technologies cannot perform adequately without the use of a conformal coating due to the tight spacing of leads and land traces. Conformal coatings may be used in greater thicknesses as shock and vibration dampening agents.

IPC-2221 4.5.2.1 Conformal Coating Types and Thickness This type of application brings with it the risk of mechanical stress to glass and ceramic sealed parts during cold temperature excursions, which may require the use of buffer materials. Heavy build up of conformal coatings under DIPs may also result in mechanical stress of soldered connections during thermal cycling, unless precautions are taken.