Due to the physical properties of Parylene and the method of deposition, Parylene forms a pin-hole free film on the subject substrate. Therefore, it provides an excellent barrier to both liquids and gasses. The table below lists the permeability characteristics of the Parylenes and also shows typical values for other types of conformal coatings.
Moisture vapor permeability values have been measured at thickness¹ below 0.1
Barrier Properties of Parylene C Compared with Epoxies, Silicones, and Urethanes
cc-mil/100 in2 - 24 hours *
|MOISTURE VAPOR TRANSMISSION
gm-mil/100 in2 - 24 hours **
* ASTM D1434-63T
** ASTM E96-63T