Parylene is the generic name for the poly-para-xylylenes.These Parylene materials form linear, highly-crystalline polymers but can be usefully
produced only as coatings and films. The most commonly used is Parylene C, the mono-chloro substituted compound. Parylene N, the un-substituted compound, has better high-frequency dielectric
properties, better penetrating power for coating the bore of very
small diameter tubes, and is often preferred in medical
applications. Parylene D, the di-chloro-substituted compound, has better high temperature
The Parylene Coating Process
The Parylene process is unique in coating technology and is best
described as a vapor deposition polymerization. It is carried out
under vacuum and requires specialized equipment.
1. The process begins with sublimation at about 150°C of the high
purity crystalline dimer di-p-xylylene.
2. The vapor is pyrolised at about 650°C to form the gaseous
monomer which has an olefinic structure.
3. The coating chamber is at room temperature. The vapor condenses
on all surfaces equally and can pass through holes as small as 1μ.
It then spontaneously polymerizes to form a product with a high
degree of crystallinity. The coating is absolutely conformal and
can be laid down in thicknesses from a few angstroms to 50 microns
or more depending on the requirements of the end use.