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Thin Film Conformal Coatings vs. Potting/Encapsulation

a man coating a printed circuit board with waterproof coatings

Mallory McGuinness | June 11, 2020

As the world of electronics continues to grow and evolve, printed circuit board assemblies (PCBAs) find their way into more and more products and industries. Whether you create products for consumers, the automotive industry, the military or some other field, chances are, PCBAs play a big part in your product design. You’ll need to protect them without impeding the rest of your design.

You have a few options for coating a PCBA: conformal coatings or potting and encapsulation resins. Both of these substances are organic polymers that provide chemical and thermal resistance, along with electrical insulation, to the delicate PCBA beneath them. But that’s where most of their similarities end. In this guide, we’ll discuss the differences between encapsulation resin and conformal coating and the effects they have on a PCBA.

What’s the Difference Between Conformal Coatings and Potting?

While both potting/encapsulation and conformal coatings protect a PCBA, they do so in very different ways.

Electronic encapsulation seals a PCBA within a thick layer of resin to add substantial protection against physical shock and chemical exposure alongside excellent electrical properties. Usually, this resin is dark-colored, so you won’t be able to see the board underneath it. The resin is mixed with a hardener before application, which allows it to cure to a cross-linked polymer.

So, what is potting? While the terms “encapsulation” and “potting” are used interchangeably, potting sometimes refers to the process used for PCBA encapsulation.

Alternatively, a conformal coating is a protective dielectric layer that is non-conductive. It protects from a variety of dangers like salt spray, fungus, moisture, and corrosion. The film is very thin and lightweight, having almost no dimensional effect on the PCBA or added stress to the components. Processing and applying this single-component material is easy and versatile, providing flexible options for the finished product.

While traditional coatings are single-component, some newer ones use a two-part process with polyurethane to blend the protective aspects of PCBA potting with the flexibility of coatings. Plus, they don’t use solvents, which reduces concerns about volatile organic compounds (VOCs), which are present in many low-viscosity single-component coatings and have adverse effects on people and the environment. Fortunately, even those have come a long way, as most manufacturers have worked to reduce VOCs in their coatings.

Which Is Better to Protect My PCBA — Conformal Coating or Potting?

To best protect your PCBA, you’ll have to consider several different factors of your product and how PCB resin coating and potting contribute to them.

Environmental factors play a significant role in choosing a protective material. Will your PCBA be exposed to any of the following?

The most common applications for this Parylene coating include:

  • Extremely high or low temperatures: You will have to consider the way resin can behave during use in extreme temperatures, how sudden or gradual the change is and how heat could affect production. Resin generates a lot of heat when mixed with its hardener, which can cause damage to the PCBA or the housing if it gets too hot.
  • Water, humidity, or moisture: Some conformal coatings are less waterproof than others. While the resin is typically always going to be waterproof, you’ll have to double-check that your coating is, too.
  • Physical shock: If your component might be exposed to heavy physical shock, the resin can help spread the impact out across the material and reduce or eliminate the damage to the PCBA.
  • Mechanical stress: Abrasion and scratches can become a problem in environments like assembly lines and manufacturing equipment, where high speeds and volumes are typical. Resin provides a thick layer to protect against that physical threat.
  • Chemical exposure: If your PCBA could be exposed to harsh chemicals, both resin and coatings provide exceptional protection from both exposure and submersion.

While PCBA potting offers more protective benefits, coatings hold the upper hand in design flexibility and can still provide significant protection for products in everyday environments, like consumer electronics. Only those that are in particularly challenging environments typically need PCBA encapsulation.

a printed circuit board being encapsulated with a coating

Below are some of the design factors that play into the conformal coating vs. potting compound debate.

  • Weight: Resin adds a thick block of material on top of the board, significantly increasing its weight. In many products, heavyweight components aren’t an option.
  • Thickness: Many products can’t function with the added thickness of the resin added into their design.
  • Workability: Since resin is dark and thick, you can’t see through it or easily remove it to rework the board. It could rip up the PCBA if you tried to take it off. Coating, on the other hand, is usually clear, which allows you to see through it and make adjustments if needed.
  • Housing: If the housing of the PCBA doesn’t offer much protection, the resin may be a way to protect it more thoroughly. Coatings are often used as secondary protection within a well-built housing.
  • Application: Depending on the design requirements, one option may be better for production than the other. Resin can add risky heat during application and takes longer to cure. Conformal coatings tend to be quick-drying and can be applied in several ways, such as painting it with a brush, spraying it on, dipping the PCBA, and using robotic systems. At HZO, we use a process called chemical vapor deposition (CVD) to coat our products, offering even coverage without stressing the components.

Conformal coatings are an excellent way to protect a PCBA from common threats without paying for the added weight and cost of encapsulation.

Here at HZO, we use a coating called Parylene, which is biocompatible — meaning it’s great for the medical devices industry — and extremely thin. It is clear and excellent for waterproofing and liquid protection. We also offer other plasma-based nanocoatings that we can use to meet specific requirements and business needs. We’ve put together a page all about particular scenarios in which these two materials can protect your PCBA.

Conformal coatings are an excellent way to protect a PCBA from common threats without paying for the added weight and cost of encapsulation.

Pros and Cons of Potting/Encapsulation

Designers often choose PCBA encapsulation for products in heavy-duty environments, as it offers excellent protection against many damaging agents.

Some of the benefits to PCBA potting include:

  • Provides added protection against chemical, thermal and physical risks, including water and shock.
  • Offers better performance for high-speed and high-volume work in industrial environments.
  • Has VOC-free options.

Some disadvantages of PCBA potting are:

  • It makes it difficult to inspect or rework the PCBA.
  • Causes possible design issues due to the added weight and thickness.
  • A more complex application process, especially regarding heat and two-part mixing.

Pros and Cons of Conformal Coating

Conformal coating is more popular than potting. It offers plenty of protection for many consumer products outside dangerous exposure environments and provides more design flexibility. If, however, your product will be used in rough applications, it may not offer all the necessary protections.

Here are some of the pros of conformal coatings.

  • Thin and lightweight, offering superior design flexibility and no stressed components.
  • Offers protection from low-level issues like salt spray, dust, moisture, and corrosion.
  • Offers a variety of application methods.
  • Newer options with low VOCs.
  • Long lifespan.

The negatives of conformal coatings include:

  • Offers less robust protection against heavy-duty threats.
  • Contains VOCs within the solvents, though these are becoming less and less abundant.

Contact Us Today to Protect Your PCBA

If you’re still unsure about which option is best for your PCBA, our expert team of HZO engineers can help. Conformal coating is our deep domain expertise, and our technology is versatile, creating opportunities for unique, effective protection. We realize that your needs are just as unique as our coatings, which is why we will work closely with you to provide custom coating solutions.

To learn more, contact us via email or give us a call today at 1-877-757-4496.

We realize that your needs are just as unique as our coatings, which is why we will work closely with you to provide custom coating solutions.

Mallory McGuinness

Mallory is an electronics protection evangelist who writes content for HZO. In her free time she is reading non-fiction, and hanging out with her beta fish, King Awesome.

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