Parylene conformal coatings and their applications for electronics

The author describes the properties and process features of parylene along with several general areas of usage and specific applications presently being practised. In particular, the voltage breakdown characteristics of parylene are illustrated. It is noted that parylene is a unique engineering material that has proven to be a problem solver. It is not limited to normal dimensional problems associated with dip and spray coatings. Due to its application by vacuum deposition, parts so small that they cannot be seen with the naked eye can be precisely conformally coated to thicknesses that can generally be controlled to ±10%. Typical parylene thicknesses range from a few thousand angstroms to about 75 μm depending on the function the parylene film is to perform. It is concluded that when environmental protection, thin insulation, low and greaseless friction, and/or immobilization of particles are required, parylene should be one of the materials investigated