5 Key Properties of Parylene

Since its discovery in the 1940s, Parylene has established a strong presence as the ideal conformal coating for a variety of applications. Given its unique blend of properties, it presents itself as an unparalleled conformal coating option, depending on the application being coated. There are several distinct properties of Parylene, including electrical properties, broad temperature stability, chemical resistance, biocompatibility and uniformity.

Electrical Properties

Parylene possesses exceptional electrical properties, notably its low dielectric constant and high dielectric strength. These attributes establish Parylene as a desirable coating candidate for an array of applications across multiple industries. Parylene has long been used in the electronics industry as a coating for printed circuit boards (PCBs), in particular. The use of Parylene to coat PCBs serves to protect the board from electrical interference while allowing the design of smaller, more compact boards.

Furthermore, Parylene’s dielectric barrier properties make it an attractive option for medical implants, because it forms an electrical barrier between the device’s electronics and the electrical signals produced in the body. Although Parylene is inherently equipped with high dielectric strength, designers can increase dielectric strength, if necessary, by applying a thicker coat of Parylene to the substrate.

Broad Temperature Stability

Another unique property of Parylene is its ability to withstand temperature extremes. Demonstrating thermal endurance, Parylene C can perform reliably in atmospheric conditions for 10 years at 80°C without significant loss of physical properties. In a vacuum, however, Parylene can perform in temperatures in excess of 200°C.

Parylene functions well in cold temperatures, too. Even at -165°C, the coating can be folded in half and back six times before cracking. Heating the coating from two degrees above absolute zero to room temperature won’t affect it. The coating will be as strong, from both a physical and dielectric standard, as it was previously.

Chemical Resistance

Parylene offers a high degree of chemical resistance. At room temperature, the coating demonstrates excellent chemical resistance to acids, bases and solvents. In fact, it will not dissolve when exposed to solvents up to 150°C.

Parylene also withstands common chemicals. Per military specifications, it can withstand a 100 hour salt spray test without affecting performance. It also is chemically inert, thereby relatively unaffected by acidic or alkaline elements. These particular properties make Parylene well suited for use in medical implants which are placed inside the human body.

Biocompatibility

Biocompatibility is one of Parylene’s most distinctive properties. Compliant with USP Class VI biocompatibility requirements, Parylene is a viable and proven coating option for a range of medical device applications. Consequently, engineers can leverage the various benefits of the conformal coating to enhance life-critical and life-saving products. Medical implants such as stents reap the additional benefits of Parylene’s dry-film lubricity, which facilitates implant placement, and its use as a drug-delivery vehicle. Parylene is also suitable for use in a range of applications that span catheters, needles, electrosurgical tools, medical electronics and cardiac-assist devices.

Uniformity

One of Parylene’s most desirable characteristics its truly conformal nature. Parylene provides uniform coating thickness on the top, sides and corners of substrates, every area of the coated product receives equal protection. Circumventing the need for an intermediate liquid stage, Parylene is applied through a vapor deposition process, preventing voids and ensuring that all exposed substrates are effectively and uniformly coated. As a result, the process is ideal for coating complex applications that may be exposed to harsh environments.

These are just five of the many properties, characteristics and benefits that have established Parylene as a leader in conformal coatings. Parylene conformal coatings widely benefit the medical device, electronics, transportation, aerospace and defense industries, and provide valuable protection to applications ranging from life-saving medical implants to PCBs on satellites orbiting the Earth.