Parylene’s Deposition Rate & Application Time

What’s Parylene Again? 

Parylene is a polymer based off of paraxylene. Parylene is formed from the pyrolysis of the powder dimer (di-p-xylene) in a vacuum chamber. The now gas, is then deposited onto a cooler, room temperature substrate within the vacuum chamber. Parylene is applied in the chamber as a gas so it can disperse evenly throughout the chamber to target surfaces. This material forms as a clear polymer (plastic) film. This is called the vapor deposition process.  

Deposition Rate

The proper deposition rate will give an acceptable coating in the shortest possible time. Generally, the slower the deposition, the more consistent and clear the Parylene will be. From the viewpoint of the coating quality, you cannot coat too slowly, but coating too quickly can definitely cause cloudy, whitish Parylene and possibly uneven coating thickness. 

For Parylene C, the deposition rate will typically be about 5um per hour (0.0002” per hour); for Parylene N, 762 nm per hour (0.00003 “per hour). The deposition rate is indirectly controlled by regulating the pressure in the deposition chamber.

How long in hours?

While parylene coatings are typically thin, they do deposit quiet  slowly. The fastest-depositing variant of parylene, Parylene C, usually deposits at a rate of 0.2 mils or 5 microns per hour. This means that a 75 micron coating would take approximately 15 hours. Parylene N deposits even more slowly.

Overall, this process might take from a few hours to over 24 hours depending on the coating thickness we are aiming for, customer contingent. The time required to reach certain thickness is controlled by dimer mass, deposition rate, temperature and other factors.

Contact Para-Coat today to discuss your application! 

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