Parylene vs. Teflon

When it comes to conformal coating, you have a variety of options depending on the scope and needs of your specific project. However, two choices often prove to be superior no matter the application: parylene and Teflon. Here's what to know about each coating type and how they compare.

Comparing Parylene and Teflon

Conformal coatings like parylene and Teflon are designed to increase consumer product lifespan, ensure proper performance of electronics, protect against extreme environments, and more. They have found homes in a variety of endeavors, from aerospace travel to medical equipment, and continue to be a vital choice in many projects.

However, parylene and Teflon are not interchangeable. It's important to understand the differences between these two coating types before choosing one for your needs.

Parylene

Parylene was discovered in 1947, when Michael Szwarc performed thermal decomposition of p-xylene at high temperatures. The result was a polymer that would go on to change the world in significant ways. Other researchers contributed to these changes by identifying different parylene types and production methods, even creating 20 different types of this polymer. However, only three remain relevant today: Parylene C, Parylene D, and Parylene N (though Parylene F is used on rare occasions).

Each type has its own properties, but in general, parylene acts as a thin, pinhole-free coating capable of adhering to unusually shaped and sized substrate surfaces. Parylene is also highly reliable, providing protection against:

Temperature extremes.
Rust.
Mold.
Chemicals.
Corrosive gases.

Parylene advantages include:

Even deposition: Because parylene is applied in a gaseous form, it can easily and effectively provide an even coating to surfaces with crevices, angles, or irregularities. The resulting coat will not lift at the edges or create ridges, leading to a smooth, reliable finish.
High stability: Parylene is inert and resistant to temperature extremes, making it a highly stable choice for many applications. It can also be sterilized without breaking down or otherwise jeopardizing its structure.
Bio-compatibility: Parylene has a bio-compatible structure, which means it will not interact negatively with the body when used for medical devices.
Transparency: When applied properly, parylene coating is clear and does not absorb visible light. The result is a transparent but protected surface.
Simplicity: Despite its original creation occurring in high temperatures, modern parylene is applied at room temperature. This removes one variable--temperature extremes--from the application process and protects substrate surfaces from thermal stress. Parylene also doesn't require conventional curing, meaning there is no mechanical or temperature stress during this process.
Environmental friendliness: Other coating types create high levels of gaseous byproducts and contain high VOCs. Parylene is a comparatively green choice.

Teflon

Teflon is the commercial name for polytetrafluoroethylene (PTFE). It was discovered by Dr. Roy J. Plunkett through experimentation with tetrafluoroethylene (TFE). Further tests indicated that the substance couldn't be polymerized and was highly stable, and other researchers contributed to additional studies to determine more characteristics. Ultimately, PTFE was registered as Teflon in 1945.

Like parylene, Teflon has many uses and can protect against a variety of extreme environments. For example, its high melting point makes it a particularly effective choice for high-temperature applications--and this, combined with its slippery surface, is why Teflon is a popular coating for non-stick pots and pans.

Teflon has many other things in common with parylene, like its high conductivity characteristics and chemical resistance. It's also used in some of the same industries, like aerospace. However, unlike parylene, the coating process is not ideal for many applications, interfering with the structure or performance of certain substrates; furthermore, the coating can produce particulates that impede project reliability, especially in medical applications.

How do Parylene and Teflon differ?

While Parylene and Teflon share some similarities, there are several key differences to consider when selecting a coating material. These differences include:

Coating thickness: Parylene coatings are typically much thinner than Teflon coatings, which can be advantageous in applications where a low-profile coating is required.
Application process: Parylene coatings are applied through a vacuum deposition process, which can be performed at low temperatures and is less likely to damage sensitive components. Teflon coatings, on the other hand, typically require higher temperatures and specialized equipment to apply.
Adhesion: Parylene coatings adhere well to a wide range of substrates, including metals, plastics, and ceramics. Teflon coatings, on the other hand, may have difficulty adhering to certain substrates.
Durability: Both Parylene and Teflon coatings are durable and offer excellent resistance to moisture and chemicals. However, Parylene coatings may be more resistant to wear and abrasion than Teflon coatings.

How to choose between Parylene and Teflon?

Choosing the right coating material for your application depends on several factors, including the substrate material, the required coating thickness, and the environmental conditions the coated component will be exposed to. In general, Parylene coatings are ideal for applications where a thin, conformal coating is required, and the substrate material is sensitive to high temperatures or chemical exposure. Teflon coatings, on the other hand, may be better suited for applications where non-stick properties or high-temperature resistance are required.

To determine which coating material is right for your specific application, it is recommended to consult with a coating expert who can evaluate your specific requirements and make a recommendation based on your needs.

Conclusion

Parylene and Teflon coatings are both excellent options for a variety of applications. While they share some similarities, they have distinct differences that should be carefully considered when selecting a coating material. By evaluating your specific needs and working with a qualified coating expert, you can select the coating material that best meets your requirements and provides the optimal performance and protection for your components.