• 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:

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.

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.

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.

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.