The Cost of Parylene Coating vs. Other Conformal Coatings

Parylene is widely regarded as the ultimate conformal coating for safeguarding devices, components, and surfaces in various industries due to its exceptional ability to prevent the infiltration of gases, liquids, or radiation onto circuit board components.

The perceived cost of Parylene is a problem, however. This article will explore the cost of Parylene when compared to other coatings.

Acrylic Resin (Type AR)

Acrylics are usually the least expensive form of conformal coating. The coating itself is relatively inexpensive. It is also easy to apply and remove, keeping costs low even when rework is required.
Acrylic coatings are perhaps the most popular of all coatings due to their ease of application, removal, forgiving nature and cost. Acrylics dry rapidly, reaching optimum physical properties in minutes, are fungus resistant and provide long pot life.

Additionally, acrylics give off little or no heat during the curing process, eliminating potential damage to heat-sensitive components. Additionally, they do not shrink during the curing process and have good humidity resistance and exhibit low glass transition temperatures.

Acrylic coatings typically consist of a solution of a thermoplastic acrylic polymer dissolved in a blend of organic solvents which dries by simple solvent evaporation. This means that acrylic coatings will soften at high temperatures and are also easily removed to effect board repair.

Polyurethane Resin (Type UR)

Polyurethane is the second least costly of the coatings due to its low material costs and the many ways it can be applied to components. The coating is available as single component, two component, UV curable and water-borne systems.

As a group, polyurethane coatings provide excellent humidity and chemical resistance, plus outstanding dielectric properties for extended periods. This makes them one of the most popular coatings when it comes to protection of the critical operation of printed circuit boards. That said, polyurethane coatings can require lengthy cure cycles to achieve full or optimum cure. What’s more, removal of polyurethane coatings can be difficult due to their very high resistance to solvents.

Silicone Resin (Type SR)

Silicone coatings are the third most costly of the coatings behind epoxy and Parylene. Silicones are most widely used in high-temperature environments due to their ability to withstand prolonged exposure to high temperatures.

This attribute has made them the primary choice for under-the-hood automotive applications. They are also capable of being applied in thicker films making them useful as a vibration dampening and isolation tool, if the coated assembly is to be placed in a high-vibration environment.

Rework of silicone coated assemblies can sometimes be difficult due to their chemical resistance. Reworking silicone is also difficult because—unlike acrylic and polyurethane coatings—they do not vaporize with the application of heat.

Epoxy Resin (Type ER)

Epoxy is the second most costly coating—behind only Parylene.

Epoxy coatings are very hard, usually opaque and good at resisting the effects of moisture and solvents. Usually available as two-component compounds, these rugged coatings provide good humidity resistance and high abrasion and chemical resistance. Additionally, epoxy coatings possess excellent chemical and abrasion resistance, but they can also cause stress on components during thermal extremes.

Epoxy coatings are, however, virtually impossible to remove chemically for rework. Any stripper that attacks the coating will almost certainly dissolve the components underneath the coatings as well, including printed circuit board themselves.

Parylene (Type XY)

While Parylene may come at a premium, its unmatched performance stands out when top-notch, dependable protection is a must. Parylene is widely regarded as the paramount coating for safeguarding devices, components, and surfaces in various industries including electronics, instrumentation, aerospace, medical, and engineering.

Parylene is unique in that it is applied in a gas form, directly on the surface at room temperature. Parylene is chemically inert, making it an excellent barrier material in a wide variety of harsh environments—including inside the human body.

One notable aspect of the Parylene process is its suitability for coating the undersides of low-profile devices. The coating can be applied much thinner than other coatings, and because the coating goes anywhere air can go, it will apply uniformly even in tight spaces.

The Best Way to Get Accurate Quotes on a Parylene Coating Project

For an accurate understanding of project costs, partnering with a seasoned conformal coating provider is crucial. Expertise in applying various coatings signals the provider’s capability to identify the optimal protection for a device.