Here at Para-Coat Technologies, we are often asked, “Can I use Parylene for my product?” The number of material surfaces that can be coated with parylene is significant. In the graphic below a notable amount of industrialapplication examples that can use Parylene conformal coating are listed.
But Wait, What is Parylene?
Parylene is the generic name for a unique series of polymers based on paraxylene. Parylene is formed in a vacuum environment from a solid parylene “dimer” – that is in powder form – which is placed inside the vaporizer and pumped into the furnace for pyrolysis, where it is heated and turns from its solid state to a gas. From here, parylene is then deposited on the much cooler, room temperature item that is within the vacuum chamber, or coating chamber. Parylene is then applied in the vacuum chamber as a gas to evenly disperse throughout the chamber to target all surfaces. This creates an extremely conformal coating that entirely covers grooves, crevices, gaps, and even sharp edges. As the parylene settles, it forms as a clear polymer (plastic) film. Access parylene is then pumped out of the chamber with the vacuum pump into the cold trap.
Parylene Properties
Parylene films are notable for their material properties, including excellent dielectric performance, good abrasion resistance, superior chemical resistance, low thermal expansion, and more.
PCT’s Parylene Types and Their Uses
Here at PCT we utilize the purest dimer on the market, 99.9% pure. PCT uses the two most common types of Parylene, Parylene N and Parylene C. Each of which has its own unique electrical and physical properties.
Parylene N
Parylene N is a completely linear, highly crystalline material. It’s a primary dielectric, exhibiting a very low dissipation factor, high dielectric strength, and a low dielectric constant invariant with frequency. It is able to penetrate crevices more effectively than Parylene C because of the higher level of molecular activity that occurs during the deposition process.
Parylene C
Parylene C is still produced from dimer however it is modified by the substitution of a chlorine atom for one of the aromatic hydrogens. Parylene C deposits on substrates at a faster rate than Parylene N and is an excellent barrier with a useful combination of electrical and physical properties, plus it has a very low permeability to moisture and corrosive gasses.
To recap:
Parylene C – the most widely used type of Parylene. Has the lowest permeability to moisture and gas, is most suitable for substrates that will be exposed to corrosive environments.
Parylene N – an excellent dielectric and halogen-free, is suitable for applications where sustainability is being prioritized.
In conclusion, if your product needs a barrier layer that provides protection from moisture, corrosion, salt spray, solvents or airborne contaminants consider Parylene. If your product needs a coating that is chemically inert, ultra-thin, pinhole-free and conforms to components evenly and consistently consider parylene. If your product needs a powerful insulator with very high dielectric strength then you should consider parylene for your protective conformal coating.