What Is the Price of Parylene Conformal Coating?
Posted by Sean Horn
Friday, July 8, 2016 7:30
@ 7:30 AM
Parylene is often considered the ultimate conformal coating for the protection of devices, components, and surfaces in the electronics, instrumentation, aerospace, medical, and engineering industries.
Parylene is chemically stable, which makes it an excellent barrier material. It’s resistant to solvents and moisture, has incredible dielectric strength, and provides completely uniform coverage.
Engineers tend to love Parylene, for all the reasons listed above. The perceived cost of Parylene, however, sometimes puts a damper on their excitement, as it is often quoted as the most expensive of all possible coating options for a project.
So, how much does Parylene cost?
The answer is: it depends.
Ultimately, there are two factors that go into the cost of Parylene:
- Raw material costs.
- Labor costs.
What Is Parylene?
Parylene is the trade name for a family of polymers used to coat and protect objects from moisture, dielectric effects, and other environmental damage.
Raw Parylene “dimer” comes in a powder form.
A typical Parylene coating run uses about a pound of raw Parylene, which costs anywhere from $200 to $5,000 per pound.
The powder is then vaporized and pulled into special vacuum coating chambers—which contain the objects to be coated.
The Parylene vapor deposits on all exposed surfaces in the vacuum chamber. This process leaves behind a thin, protective coating on the objects in the container. The coating “conforms” perfectly to the object. This is why Parylene is called a “conformal coating.”
The Parylene layer protects the object from moisture, extreme heat and cold, dielectric interference, mold, and many other problems that might cause the underlying device to fail or malfunction.
In this way, engineers use Parylene to create a barrier to protect circuit boards and other objects from environmental damage. This allows circuit boards and electronic devices to function in places they never could without the protective coating. This includes use on NASA vehicles and even on medical implants for use inside the human body.
How Parylene Is Different than Other Coatings
Parylene is not the only choice engineers have for conformal coating.
There are four other major “wet” conformal coatings: polyurethane, silicone, acrylic, and epoxy. The four wet coatings are applied as a liquid, either by brushing, dipping, or spraying the object with the coating material. A drying process allows the wet coatings to cure, resulting in a protective coating layer on the device.
Each coating has advantages and disadvantages.
When compared to the wet coatings, Parylene often provides the very best performance, especially in situations when you need to ensure completely pinhole-free coating, or when you have small tolerances.
Parylene is not the best in all situations, however. You’ll need to work with an experienced conformal coating provider to evaluate your specific needs.
When looking for a coating partner, always choose one that has expertise and experience applying all five of the major coating types. That way you don’t get forced into a coating choice that might not be optimal for your project or your budget.
Object Size & the Effect on Final Cost
As mentioned, a pound of Parylene dimer costs anywhere from $200 to $5,000 per pound, with cost differences dictated by the type and quality of the Parylene.
One excellent way to lower Parylene’s cost per item is to coat as many devices as possible in a single run.
The Parylene coating process uses a vacuum chamber with a fixed capacity. The number of items that can be placed in that chamber will vary considerably depending on the size and shape of the objects being coated.
The more items that can be placed in the chamber, the lower the cost per item for that batch of objects.
Parylene Labor Costs
Like all coating processes, masking is usually the most labor-intensive step. Parylene, however, requires especially careful masking.
Parylene molecules will penetrate anywhere that air can. As a result, great care needs to be taken during the masking process to ensure every connector is adequately sealed and all tape is firmly pressed against the coating keep-out areas.
Another factor that will result in increased labor costs is the increased time spent per part to increase Parylene adhesion. Spending extra time cleaning products and applying different adhesion-promotion mediums will result in increased labor times—and increased costs.
The No. 1 Thing You Can Do to Control Costs in Parylene Coating
The No. 1 way to keep your costs in line with a coating project is to avoid mistakes in the first place. The importance of properly preparing your device cannot be stressed enough.
As you work with your coating provider, here are three questions you need to answer in order to ensure Parylene coating success:
1. Is Parylene Really the Best Choice for My Project?
Every project is unique. Parylene is often the best choice for conformal coating protection. But sometimes your performance requirements mean a different coating is better suited to your project.
Before you go any further, make sure you’re working with a conformal coating provider with experience in all five major coating types. They will be in the best position to help you make the right conformal coating choice.
2. Have I Provided All Necessary Information?
Your coating provider needs to know all your requirements. Document what you expect and what your expectations are for the coating and the coating process.
Explain your situation, your expectations, any issues you’ve had in the past, and if this is a one-time issue or will be an ongoing project.
Whether you’re working with an in-house team or an outsourced provider, have the conversations about expectations and performance before the coating process begins.
It will be costly to fix issues after the coating process has started.
3. How Will the Device Be Cleaned Prior to Parylene Coating?
Water will remove most ionic contaminants, but the water must be pure. Otherwise, it can leave behind salt and other compounds when it evaporates.
Your coating provider should also thoroughly clean your device using a solvent or a surfactant in order to remove nonionic contaminants.
Again, the most effective way to prevent Parylene coating failures and control costs is to ensure you’re working with an experienced conformal coating provider.
As you decide what conformal coating provider to work with, look for one that can confidently answer the questions we’ve listed here. That’s a good sign the company can help you get the protection you need for your device.
To learn more about how to keep parylene costs low, download our whitepaper: