Medical implants save lives, but inorganic materials can irritate surrounding biological tissue and cause potentially severe problems for the patient. Parylene conformal coatings significantly reduce this risk. Likewise, in the transportation, aerospace, defense, and semiconductor industries, Parylene conformal coating—primarily Parylene C—provides protection and enhanced operation for vital and mission-critical electronic systems and technologies that we depend on for convenience and safety every day.
VSi Parylene is one of the leading providers of Parylene coating products and services. Our mission is to provide improved accessibility not only to Parylene coating-as-a-service but also to Parylene coating on-demand, making Parylene coating available to manufacturers around the world. Through our Parylene coating technology, we enable our clients to take conformal coating into their own hands.
First discovered by British chemist Michael Szwarc in 1947, Parylene is an extraordinarily useful, high-performance polymer conformal coating with a vast range of beneficial properties. Its advantages compared to other forms of conformal coating grant it incredible versatility in a wide range of applications and industries such as transportation, aerospace, defense, semiconductor, and medical manufacturing. Parylene C in particular provides particular benefits as a conformal coating in this industry and many others—for example, dramatically reduces the risk of a patient’s adverse reaction to implanted medical devices.
What is Parylene C?
Poly paraxyxylene, more commonly known as Parylene, is a crystalline polymer with a backbone consisting of para-benzenediyl rings connected by 1,2-ethanediyl. Other polymers with the same backbone comprise a family of Parylene polymers. This shared backbone imbues Parylene polymers with similar properties, though their differences provide advantages in certain areas. There are three varieties of Parylene considered commercially viable, one such member of that family being Parylene C: a particular variant of Parylene with many improved properties over the other two varieties, Parylene N and Parylene AF-4.
Hydrophobic, low-friction, stable and bio-compatible, a Parylene conformal coating on your parts provides incredible benefits as a form of waterproofing, electrical insulation, dry lubrication, and beyond. As a “green” polymer, its production and application is sustainable and minimizes the use or production of hazardous substances as well.
Parylene C is a chlorinated Parylene, in which one of the hydrogen atoms in the aryl ring of a Parylene molecule has been replaced by an atom of chlorine. This variety’s properties make it the most commonly used variety of Parylene for conformal coating.
Is Parylene C superior to other Parylene variants?
No single variety of Parylene is superior to the other in all circumstances. Rather, each variety and derivative of Parylene has unique advantages and disadvantages over their peers that make them better suited for certain conditions and applications. Depending on the situation, certain varieties of this conformal coating material perform better than others. Parylene C’s composition and material properties make it a superior conformal coating in several key areas:
Parylene C has high biocompatibility
Parylene C has long been used as a protective coating for medical devices due to its FDA-approved biocompatibility—its ability to exist alongside living tissue without negatively interacting with it. Because Parylene is chemically inert and hydrophobic, it provides superior barrier properties that protect both the device and the body it has been implanted in—preventing corrosion, providing chemical resistance, and preventing liquid ingress.
Parylene C has high mechanical strength
The tensile and yield strength and wear resistance of Parylene C is substantial, and a thin conformal coating on a material confers these properties to the underlying material. Along with other properties of Parylene C, such as its completely conformal properties, Parylene is a powerful asset for ruggedizing materials. In particular, they can physically reinforce and add strength and rigidity to delicate connections on printed circuit boards and other fragile components. In terms of Young’s Modulus, tensile strength and yield strength, Parylene C is superior to the other common varieties of Parylene.
Parylene C reduces friction
A sub-micron layer of Parylene has a low coefficient of friction comparable to Teflon. A thin and uniform conformal coating of Parylene C acts as a dry lubricant and can be particularly useful for medical devices such as catheters, acupuncture needles, and microelectromechanical systems. The presence of friction in medical devices can cause patients undue irritation during surgical operations and implantations. A low-friction Parylene conformal coating, in addition to the many other benefits it confers, minimizes irritation to the patient, making it an essential benefit to medical implants and other medical devices. Dry lubricity provided by a Parylene C conformal coating also proves useful for components such as silicone parts and cables, o-rings, seals and gaskets.
Parylene C is a superior electrical insulator
All Parylenes do not conduct electricity, some better than others. The uniformity of and lack of pinholes and other point defects in a coating of Parylene on an electronic component separates conductive areas, isolates electrical grounds, and prevents arcing, greatly lowering the risk of failure compared to some other forms of conformal coating. While Parylene C does not have the highest dielectric protection value per mil (25um) compared to other Parylene varieties, the cost to dielectric benefit of Parylene C often beats the other varieties.
Parylene C works in extreme temperatures
Though Parylene C has a lower melting point than some other varieties (290 degrees Celsius for Parylene C compared to 420 degrees for Parylene N), its long- and short-term temperature limit is higher. In addition, Parylene C, like some other varieties of Parylene, is superior in its flame retardant properties compared to Parylene N due to containing halogens with flame-retardant properties—if exposed to fire, a Parylene N coating will continue to burn for a short time after the flame is removed, for example, while a Parylene C coating will immediately self-extinguish.
Common applications of Parylene C
Parylene’s myriad properties provide a wealth of applications in many manufacturing industries, such as medical manufacturing and in the development of electronics for the transportation, aerospace and defense, semiconductor, and elastomer industries.
Common applications of Parylene C conformal coating include:
- Providing barrier layers for stents, probes, defibrillators, pacemakers, medicine bottles, hearing aids and intraocular implants
- Waterproofing, ruggedizing, and strengthening PCBs and plastic and elastomeric materials used in extreme or harmful environments
- Improving the compatibility of 3D printed parts with other chemicals
- Protecting metals from corrosion
- Providing dry lubricity for catheters, guidewires, silicone parts and cables, o-rings, seals and gaskets
- Reducing the effects of vibration on circuit boards and electronics
- Strengthening fragile components by adding rigidity
- Protecting sensors in high-temperature environments
- Providing conformal coatings for cryogenic applications
- Protecting electronics during sterilization by forming autoclavable barrier layers
Improving the quality of medical device implantation with Parylene C
The superior corrosion prevention and protective properties of Parylene conformal coating are incredibly useful, especially to the medical industry, as mentioned above. When it comes to implantable medical devices, Parylene C’s properties intersect to form a superior conformal coating. Electronic devices such as pacemakers, stents, defibrillators, cochlear implants, intraocular implants and other implants such as artificial joints benefit tremendously from Parylene’s hydrophobia and its barrier properties. These properties prevent corrosion of the devices’ materials, dramatically reduce the risk of adverse tissue reaction, and drastically prolong the devices’ operational lifetimes within patients.
Waterproofing and ruggedizing electronics with Parylene C
Parylene C’s hydrophobic properties and mechanical strength make it ideal for waterproofing and providing superior protective barrier layers for electronics. The excellent waterproofing, extreme chemical resistance, outstanding dielectric properties, and uniform coverage of Parylene contribute highly to increasing the resilience of electronic devices in applications where failure, field repair, or warranty claims are not a practical option. The hydrophobic properties of Parylene conformal coating are also especially useful for biomedical materials.
Further Parylene coating case studies
You can learn more about the properties and applications of Parylene C and other Parylene varieties by checking out the case studies and other resources available here on our site:
How VSi Parylene uses Parylene C
Though Parylene was first discovered by Michael Szwarc in the late 40s, it was not until nearly 20 years later that a more commercially viable method of producing it was developed by Union Carbide chemist William F. Gorham. As you’ve read, Parylene conformal coating has proven itself since then to be a highly effective solution to a wide range of problems plaguing a wide variety of manufacturing industries—and a solution that in many cases out-performs other forms of conformal coating such as epoxy, polyurethane and silicone. Parylene C is one of the most useful and widely-used varieties of Parylene, and is especially effective as a barrier layer and dry lubricant for medical implants.
How VSi Parylene solves a major problem with Parylene coating
However, for as many problems as it solves, there is also a major problem with Parylene. Since its discovery, Parylene conformal coating has been available almost exclusively through third-party providers. For a technology so necessary for so many industries, especially in medical device manufacturing, this service-only Parylene coating model represents a significant pain point for customers.
The exclusive reliance on third-party Parylene coating service providers has resulted in added costs for manufacturing and additional complexity to manufacturing supply chains. The current status quo for Parylene C conformal coating, as it has stood for these past five decades, means that taking advantage of this technology has not been an option for customers who cannot afford the extra days added to their supply chain by shipping their devices and materials to third-party facilities for conformal coating.
This situation worsened during the COVID-19 pandemic, where businesses who relied heavily on multi-source, just-in-time supply chains and who primarily outsourced their Parylene coating were the most harmed by shipping delays, shutdown mandates, and low supplier capacities.
While VSi Parylene does provide in-house Parylene C conformal coating as a service for customers who prefer it, our mission is to transform the status quo and provide a new option for those who are struggling under it—and this new option is the Parylene On Demand (PODTM) integrable production system.
VSi Parylene’s Parylene On Demand System
We sell an in-house Parylene coating system that eliminates the bottlenecks and delays caused by the need for medical device manufacturers to ship parts to a third-party Parylene coating service provider. By removing this bottleneck, manufacturers can reduce the lead times, costs and technical risk of their existing supply chains—an essential task that once took days can now take mere hours. This is our solution to the Parylene supply bottleneck that has limited accessibility to Parylene C conformal coating in the past.
VSi Parylene provides comprehensive support for Parylene coating. Our Parylene development lab’s experts in process engineering work with our customers to bring their deep expertise into a broad range of manufacturing environments.
Through our three-stage process through the prototype, development and production stages, we first help you find out if Parylene is the right solution for your application and understand the costs and benefits of using Parylene coating; next, we work with you to build a robust and efficient process that will scale to meet your demand. Finally, after the process is qualified and locked, we work with you to determine how to meet your production demand—whether through coating-as-a-service at our facility or through an in-house solution that enables you to produce high-quality Parylene C conformal coatings at your own facility.
The benefits of in-house Parylene C production include:
- Enabling you to meet increased demand or lead time requirements
- Lowering your total costs of manufacturing by eliminating non-value add operations and shipping expenses
- Eliminating technical risk for high-risk products
Our solution for bringing in-house Parylene coating technology into our customers’ businesses is designed to be easy to use and to integrate simply into any new or existing supply chains. With PODTM, Our experts work closely with our customers to custom-tailor a Parylene deposition process that will work with their needs, install and optimize the machine, and provide on-site training to their staff.
About VSi Parylene
VSi believes in a transparent, friendly approach to Parylene coating. Since our founding in 2007 we have worked tirelessly to lead the way in innovation in the Parylene industry, pushing the limits of what’s possible to turn an interesting product into the best-in-class.
Do you have questions about our Parylene C conformal coating solutions? Get in touch with us: