Why is Parylene Coating Conformal?

why is parylene conformal

Posted on December 23rd, 2021 by

Parylene (p-polyxylylene) conformal coatings are unique due to their capacity to be polymerized and deposited by the chemical vapor deposition (CVD) method onto surfaces near room temperature. As a result of this process, pinhole-free, high purity, extremely thin coatings are formed out of dimer materials.

When it comes to conforming to complex or unusual surfaces, Parylene is one of the best polymer coatings for moisture resistance. This attribute and the fact that Parylene is a stable chemical compound that creates an excellent barrier make it the optimal choice where resilient electronic products are a mandate. But why is Parylene coating conformal?

Download HZO’s Parylene datasheet to learn more about Parylene’s properties


Why is Parylene Coating Conformal?

Liquid coatings with application methods such as dipping, brushing, or spraying may cause the coatings to exhibit meniscus forces or pull away from edges, which does not occur with Paylene deposition. With CVD, the coating penetrates around and beneath closely spaced components with consistent, uniform buildup, allowing for substantial physical and electrical protection with a substantially thinner layer than conventional coatings.

Parylene Deposition Process

Thus, the Parylene coating process explains why Parylene is so conformal. You can read an in-depth description of the CVD process versus PECVD in our blog on the subject; below are some general benefits of CVD:

Download an infographic for a visual explanation of the process


  • CVD produces coatings with complete coverage even around and beneath closely spaced chips and wires.
  • CVD deposits Parylene molecule by molecule onto substrates with precision and control.
  • The Parylene deposition process does not require a catalyst, hardener, or heat curing.
  • Polymerization does not release harmful by-products, as with other conformal coatings.

Chemical vapor deposition process

When Parylene polymers are deposited from the vapor phase with the CVD process, all sides of a component are impinged by the gaseous monomer and uniformly coated. This feature of the process is responsible for why Parylene coating is conformal.


Importance of Conformality and Uniformity

Truly conformal coverage occurs when a film precisely follows the coated component’s geometry. Conformality allows for the optimization of surface properties regardless of the shape of the part and ensures that microdevice properties such as conductance do not vary due to significant variations in thickness. Uniform thickness is critical to prevent proper reinforcement against degradation and wear.

Parylene Conformality Compared to Conventional Conformal Coatings

Parylene conformality

Along with performance concerns, achieving uniformity improves production factors such as yield rates and repeatability. With a process such as CVD, engineers have confidence that there will not be thickness fluctuations from product to product and that specs are being met. By ensuring optimum coating deposition performance is met, you can lower your total cost of ownership by keeping your repeatability and yield on target.


Parylene Conformal Coating Service with HZO

However, although a process may achieve repeatable, uniform thickness distributions, this does not mean that it is viable for your company – uptime and upfront cost must also be considered. Parylene has traditionally only been used for mission-critical applications such as medical products. HZO, a turnkey CVD process provider, has been making Parylene and its application feasible for most industries for years. Our engineers have crafted capital coating equipment that addresses upfront cost concerns and allows Parylene to be scalable. If you are interested in the powerful barrier properties of Parylene films and the benefits of its vacuum deposition process, reach out today to speak to one of our engineers.

Mallory McGuinness

As a veteran writer with over a decade of writing experience, Mallory McGuinness has spent the last two years at HZO learning about coating technology from the best minds in the industry. Professionally, Mallory is especially interested in the process of problem-solving and watching how the engineering team develops solutions that ensure business requirements are met. In her free time, you can find Mallory walking her dog Ebbie, fueling up on coffee, watching the Simpsons, and referencing the Simpsons.

All of Mallory’s blogs are reviewed for accuracy before publication.

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