- How does Parylene performance compare to liquid conformal coatings?
How does Parylene performance compare to liquid conformal coatings?
Conformal Coatings, which include Parylene (XY), Epoxy (ER), Acrylic (AR), Silicone (SR) and Urethane (UR) are the mainstays of the industry, particularly with respect to coating electronics. However, the suitability of any of these materials is largely dependent upon the application and desired properties.
Each chemistry has its advantages and disadvantages.
For example, Parylene (C) rates near the top in uniformity and chemical resistance, but breaks down under exposure to UV and to temperatures exceeding 100°C. On the other hand, Silicone is stable at temperatures exceeding 200°C, resists UV, but offers little abrasion resistance.
See our comparative tables for Parylene versus liquid conformal coatings
A sample of the relative advantages and disadvantages of each is presented as follows:
ACRYLIC (UR)
| Advantages | Disadvantages |
| Easy to remove and rework | High VOC in most cases. Where lower VOC then other issues with drying. |
| Easy cure process | Flammable solvents in some cases. |
| Formulation adjustment simple (viscosity) | Potential for reversion under certain conditions (temp & moisture) |
| Good fluorescence | Solvent concentration must be monitored carefully |
| Good moisture resistance | Maintaining viscosity can be difficult unless process controls are used |
For more information click acrylic conformal coatings.
URETHANE (UR)
| Advantages | Disadvantages |
| Good moisture barrier | Lengthy cure time |
| Good dielectric properties | High VOC (heat cure) |
| Resists abrasion | Health and environmental considerations |
| Good chemical resistance | Not ideal for low temperature exposure |
| Low reversion | Only average dielectric properties |
For more information click polyurethane conformal coatings.
EPOXY (ER)
| Advantages | Disadvantages |
| Good heat resistance (150°C) | Low flexibility |
| High mechanical/abrasion resistance | Difficult to remove, rework |
| Good adhesion | Potential for reversion (temp and humidity) |
| Good chemical resistance | Hard to maintain viscosity |
| Good moisture barrier | Average coating uniformity |
For more information click epoxy conformal coatings.
SILICONE (SR)
| Advantages | Disadvantages |
| High heat stability (200C) in general | High potential for cross contamination when used around other types of conformal coating |
| Good moisture resistance | Low coefficient of thermal expansion |
| Good dielectric properties | Low abrasion resistance |
| Good component/crevice penetration | Average adhesion (relates to cure method) |
| UV resistant |
For more information click silicone conformal coatings.
Parylene (XY), type C, N
| Advantages | Disadvantages |
| Inert, non-toxic, no VOC | High cost (slow deposition rate) |
| Solvent-free | Low UV resistance |
| Biocompatible | Not re-workable |
| Highly conformal and uniform | Low operating temperature |
| High moisture & chemical resistance | Batch process |
For more information click Parylene conformal coatings.