Shocking Performance: Parylene’s Dielectric Strength | Automotive Conformal Coatings

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Mallory McGuinness | October 1, 2020

Right now, the automotive industry is undergoing a transformation toward autonomous vehicles enabled by state of the art electronics. Forecasts predict that sales of electric cars will add up to a staggering 41 million by 2040, and it is expected that Level 4 and 5 autonomous cars will become a $60B market by 2030. As an engineer or automotive OEM, will you be at the forefront of this innovation, delivering products that exceed industry expectations? Or will you be left behind?

In part, the answer depends on the ruggedness and resilience of your technology.

Automotive electronics such as ADAS ECUs, safety systems, cameras, radars, sensors, steering, and suspension control ECUs are just a few systems that are on today’s vehicles. And that is not including EVs and hybrids, which undoubtedly incorporate more electronic components.

Because safety, comfort, and reliability depend on vehicle electronics, consumers base purchasing decisions on the dependability and quality associated with their experience. If you have a failure, your company’s reputation is on the line, and you may be left with warranty claims, recalls, and a decrease in sales. When it comes to vehicle design, reliability is table stakes with lives hanging in the balance. And an ounce of prevention is worth a pound of cure.

Therefore, it is up to you to ruggedize your electronic hardware to ensure that printed circuit boards (PCBs) live up to your company’s standard of excellence. Of course, this is a formidable challenge for vehicles. Harsh service environments present threats to reliable component performance, such as exposure to corrosives, chemicals such as oil and salt spray, and intense electrical activity.

You have got a few options when it comes to ruggedization, including potting, seals, or enclosures. But these methods add weight and require more space than typical vehicles have available.

Next-generation thin-film conformal coatings may eliminate the need for enclosures, seals, and potting, allowing for lighter, smaller assemblies so that more PCBs can fit into a vehicle system. The polymeric protection is delivered in thin layers, minimizing bulk, and as a barrier, these protective films are more reliable than commonly used seals.

View our webinar on how to improve automotive electronic performance in harsh service environments.

Conformal Coatings Won’t Work if They Don’t Work

If your coating can’t withstand the automotive service environment, it’s a moot point. Therefore, the coating you choose should be able to withstand an applied voltage without breakdown. For your industry, the dielectric strength, defined as the maximum voltage at or below which no breakdown occurs, along with general electrical properties, are critical considerations.

View a webinar about proven corrosion resistant methods delivered by Dr. Sean Clancy, Director of Coating Technology at HZO & Anti-Corrosion Expert

Parylene Exceptional Electrical Properties for Automotive

Of all the conformal coating materials (including acrylics, epoxies, urethanes, and silicones), Parylene’s electrical properties are among the best. The coatings are of high purity, so any moisture absorbed will not degrade Parylene’s electrical protection.

You should use dielectric strength, illustrated in the chart below, to evaluate the insulation effectiveness for conformal coatings. The higher the numerical designation of strength, the more likely a coating is to resist dielectric breakdown. For reference, some acrylics have a dielectric strength of 1200, epoxies 900-1000, silicone 1100-2000, while urethanes may range from 1400-30001. (Note that acrylic, epoxy, urethane, and silicone chemistries can vary and offer different ranges of protection).

Parylene coating also has lower dielectric constants than liquid conformal coatings, demonstrating an increased ability to withstand intense electrical activity typical for automotive operational conditions.


Dielectric Strength short time, V/mil (1-mil thick)
60 Hz
1 kHz

Parylene N


Parylene C


Coating Materials for Electronic Applications, Licari

Looking at the data, it shouldn’t come as a shock that Parylene can withstand substantial electrical activity common in vehicles, maintaining assembly performance, helping your cars offer more safety, reliability, and comfort.

If Nothing Changes, Nothing Changes

In our connected world, using enclosures and seals is no longer a sustainable option. The extra weight impedes “lightweighting” efforts, and the bulk hinders your ability to incorporate more electronic functionality into your product. Similarly, other coatings, such as silicone, offer good protection but must be applied at a substantial thickness.


Max Opertating Temp °C
Minimum Coating Thickness to Meet IPC Standards
Chemical Resistance

Parylene C


Parylene F (VT4)


Automotive-Grade Silicone

Low to Medium

To learn more about Parylene properties, speak to one of our SMEs today.

Download our automotive fact sheet

In the late 1970s, the cost of electronics comprised around 5% of a vehicle’s total cost, but by 2030, components will comprise 50%.

The Big Picture 

At HZO, your unique reliability challenges drive our development of new processes and chemistries, but Parylene is a critical part of our tool kit. Although Parylene’s application method, chemical vapor deposition (CVD), is costlier and slower to finish, the process allows for deep penetration into substrate surfaces, resulting in the highest levels of protection available for automotive components.

With confidence in our engineers, material science, SMEs, and processes, we’ve come to understand your problems, and we’ve come to understand how we can help solve them. We’ve developed an elegant solution to your challenges with large capacity coating chambers that are cubed, allowing for more substrates to coat simultaneously, bolstering reliability, and driving down cost. Up to two times more parts can be coated at once.

We know that automotive engineers and manufacturers are looking for a partnership, not a “buyer/seller” relationship, so we are open to implementing different ideas and flexibility, configuring specific solutions for unique problems so that we may earn your trust.

With lives at stake, we understand the criticality of component reliability and the importance of your position. That’s why we put our all into protecting what matters most to you.

Parylene exhibits many beneficial physical properties that make it a reliable corrosion-resistance solution.

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.

Ryan Moore

Ryan is a 9-year veteran to the world of protecting electronics from harsh environments and a lover of all things technology.

Discover how HZO can protect your product