1. IPC-2221
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:

2. IPC-2221
Conformal Coating Types and Thickness
Type AR - Acrylic Resin mm
Type ER - Epoxy Resin mm
Type UR - Urethane Resin mm
Type SR - Silicone Resin mm
Type XY - Paraxylylene Resin mm

3. IPC-2221
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.

4. IPC-2221
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.

5. IPC-2221
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.