The Applications and Benefits of Parylene Conformal Coating— 03 / 01 / 2019
Parylene is a versatile polymer coating which has gained popularity and is used in virtually every industry worldwide. Parylene is a common generic name for a unique series of polymers based on paraxylene. The parylenes are formed by the pyrolysis of a di-p-xylene (dimer) in a vacuum environment. The vapor is then deposited on the cooler, room temperature substrate within the vacuum chamber. Vapor phase deposition of the parylene polymer allows it to be formed as a continuous film which is truly conformal to the structure of the substrate upon which it is being deposited. Unlike liquid coatings, parylene uniformly coats all corners, sharp points and hard to reach crevices. And because it is pinhole free, it provides unsurpassed barrier protection to the environment. Parylene films provide superior protection against moisture, chemicals, solvents and gases as well as being Mil-l-46058C and FDA approved.
Because of parylene’s superior conformal properties, it can be used in an endless number of applications.
Parylene is rapidly becoming the number one coating choice for circuit boards, wire wound devices such as electric motors and stators. Along with its specialized protection properties, parylene also possesses electrical insulation properties, a low coefficient of friction and a low dielectric constant.
In recent years, Light Emitting Diodes (LEDs) seem to be everywhere. They’ve replaced the common filament bulbs in flashlights, street lights, car headlights and outdoor advertisements and traffic signage. LEDs have proven to be more reliable and energy friendly but they do present unique challenges. They are particularly susceptible to moisture, heat and ultraviolet light from exposure to sunlight. Parylene is useful in these situations because it does not add weight or distort the light yet offers maximum protection from heat, moisture and UV light.
The medical industry has the most widespread and diverse uses of parylene. The thin film of Parylene coating is biocompatible, non-toxic, extremely thin and pinhole-free. It provides barrier protection against both organic and inorganic fluids and solvents. It can also withstand various sterilization methods including E-beam, gamma and autoclave. Some examples of products coated by parylene include hypo needles, coronary stents, implantable devices, hearing aids, medicine bottles and catheters.
The automotive industry also has a need for Parylene. A vehicles complex components and electronic systems require specialized protection because they operate within an extremely harsh environment, being exposed to solvents, heat, cold, oils and salt. Parylene adheres to almost every surface and penetrates every nook and cranny, making it an ideal coating for sensors and computerized components. Parylene can be found on flow sensors, gaskets, seals, pressure sensors, circuit boards and power systems.
Even in space, parylene has proven itself to be the ideal coating of choice. It is used in everything from communications equipment to circuit boards to navigation control systems because of its insulating properties, low out gassing and high thermal and UV stability.
The aviation market also frequently experiences exposure to harsh environments. Instruments are exposed to sub-zero temperatures, UV rays, moisture and a range of chemicals and solvents. Parylene can protect flight control systems, cockpit instrumentation, displays and imaging equipment.
Parylene has a high degree of functional protection which makes it ideal coating choice for the defense industry, where exposure to rugged conditions and harsh chemicals are common. Approved brands of parylene conform to Mil-Spec, IPC, ITAR and ISO standards. They are used to coat a wide variety of products, including weaponry, radar equipment, satellite electronics, circuit boards and guidance/targeting systems.
Parylene Cost Compared to other Conformal Coatings
Parylene coating may prove to be an expensive coating option compared to alternate materials. The cost to prepare and apply Parylene to a complex part is typically more than protecting it with an acrylic, urethane or other liquid coating.
However, a less expensive coating process may not provide the necessary requirements of protection such as of conformability, solvent resistance, surface lubricity, and biocompatibility or abrasion resistance that Parylene can.
Although Parylene coating may be overqualified for simple or common coating tasks, it has cost advantages over alternate coatings in various applications. The price of conformal coating protection is based on a total cost of application. This includes the value of the part or assembly, the actual coating process and the cost to the customer to replace or repair the assembly should the coating fail while in operation.
There are also more challenging applications where the cost advantage of Parylene coating may not be immediately clear. Customers may find that while the selected liquid coatings provide apparent protection, field experience sometimes shows that full system integrity requires a coating with better performance. By applying Parylene the first time round, assemblies will experience less field failure and part replacement. Expenses, delays and other complications can be avoided all together by applying parylene at the outset.
While Parylene coating can be more costly at the outset of the project, it will ultimately contribute to a significant savings in many applications by greatly prolonging the productive life of a expensive and sometimes critical device. Because of recent advancements in masking materials and methods, along with the decrease of raw material cost, parylene coating has become a competitive high-performance coating alternative. Contact us today to discuss your application!
Blog Written By Owner-Michael Rager