Due to its excellent ability to stop the passage of gases, liquids, or radiation onto circuit board components, parylene is often considered to be the ultimate conformal coating for the protection of devices, components, and surfaces in many industries.
The perceived cost of Parylene is a problem, however.
In this article, we’ll be exploring the cost of Parylene when compared to other coatings, starting with an overview of acrylic resin and its costs. After that, we’ll work our way through epoxy, polyurethane, and silicone before ending with Parylene.
1. The Cost of 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 also that they are easily removed to effect board repair.
2. The Costs of 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.
Polyurethane coatings are very popular for coating applications. They are 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 your 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.
3. The Costs Silicone Resin (Type SR)
Silicone coatings are the 3rd most costly of the coatings behind, both epoxy and Parylene.
Silicone coatings 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.
4. The Cost of 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.
5. The Costs of Parylene Resin (Type XY)
Parylene is generally the most costly coating option available.
When you need ultimate, reliable protection, however, nothing beats Parylene’s performance.
As mentioned earlier, parylene is considered by many to be the ultimate coating for protection of devices, components and surfaces in the electronics, instrumentation, aerospace, medical, and engineering industries.
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.
A unique difference with the parylene process is that it is perfect for coating the underside 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 Your Parylene Coating Project
The best way to get an accurate understanding of the costs of your project is to ensure you’re working with an experienced conformal coating provider.
If you find a provider with expertise applying all the major coatings, it’s a good sign they have the tools necessary to help you get the right protection for your device.
To learn more about how the price of conformal coatings compare, download our whitepaper: