General FAQs


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.


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