Parylene Coatings information
- Jan 16, 2019 -
Parylene (poly paraxylylene) is a generic name for polymers that belong to a unique chemical family and are used as conformal coatings in protective applications. The coating process exposes product to the gas-phase monomer at low pressure. Through vacuum deposition, parylene condenses on the object's surface in a polycrystalline fashion, providing a coating that is truly conformal and pinhole free.
Compared to liquid processes, the effects of gravity and surface tension are negligible, so there is no bridging, thin-out, pinholes, puddling, run-off or sagging.
The process takes place at room temperature so there is no thermal or mechanical stress on the product. Parylene is physically stable and chemically inert within its usable temperature range. It provides excellent protection from moisture, salt spray, corrosive vapors, solvents, airborne contaminants and other hostile environments. Parylene provides coatings with a friction coefficient as low as 0.25 to 0.30.
These coatings are formed by the polymerization of para-xylene, which is deposited on the substrate through vacuum deposition. Thus the coating is uniform, thin, stress free and has very good mechanical properties. The coating is applicable for substrates where protection is more important than decoration.
The parylenes are polymers of the p-xylenes and their substitutions, some of which are Parylene N, Parylene C and Parylene D. The basic member of the poly-p-xylylene series is Parylene N - a completely linear, highly crystalline material. The other commercially available members (C and D) originate from the same monomer and are modified by substitution of one or two aromatic hydrogens with chlorine atoms.