Key Material properties
Parylene Type Chemical name Dielectric Strength (V/mi) Water Vapor Transmission Rate (lower value is better barrier)
(g*mm)/(m2*day)
C Symmetrical dichloro[2.2]paracyclophane 5,600 .08
N [2.2]paracyclophane 7,000 .59
D Tetrachloro[2.2]paracyclophane 5,500 .09
The symmetrical dichloro paracyclophane is true “Parylene C” and the higher the content the better since Parylene C has the best WVTR of the Parylenes, assuming proper deposition parameters.
VSi’s testing has shown a direct relationship between the improved WVTR and higher symmetrical dichloro content. Data shows an appreciable WVTR change when the purity of the Parylene C dimer drops to below 95%.