CVD uses a long chain protective polymer material called parylene. It can be deposited in vacuum. The good penetrating power of the active molecule can form no pinhole around the bottom of the element and transparent insulating coating of uniform thickness provides high quality protective coating for the component. Resist the damage of acid-base salt spray and various corrosive gas. Because the liquid is not used, there is no aggregation in the coating process, and the bridge forms the meniscus. Macromolecular materials can be classified as N type、C type、 D type、F type and HT type according to their molecular structure.
Raw material grades Film forming property | CAT N type | CAT C type | CAT D type | CAT F(VT4) type | CAT AF4(HT) type |
Density（gm/cc) | 1.1 | 1.3 | 1.41 | 1.55 | 1.5 |
Dielectric constant（1Mhz) | 2.6 | 2.9 | 2.8 | 2.3 | 2.2 |
Dielectric strength（V/Mil) | 7000 | 5600 | 5500 | 5000 | 7000 |
Minimum continuous working temperature(in the air） | -60°C | -60°C | -60°C | -60°C | -60°C |
Maximum continuous working temperature(in the air） | 60°C | 80°C | 110°C | 200°C | 300°C |
Friction coefficient-dynamic condition | 0.25 | 0.29 | 0.38 | 0.39 | 0.16 |
Coefficient of linear expansion (ppm at 25°C) | 69 | 35 | 38 | 45 | 34 |
Hydroscopicity（after 24H） | <% 0.1 | <% 0.1 | <% 0.1 | <% 0.1 | <% 0.1 |
WVTR (gm.mm)/m2.day) | 0.6 | 0.08-0.1 | 0.1 | 0.25-0.32 | 0.2 |
OTR (cc.mm)/(m2.day.atm) | 16 | 3 | 12.0-13.5 | 16.8 | 25.3 |
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