Parylene: The Military-Grade Conformal Coating
Posted by Sean Horn
Friday, August 23, 2013 8:21
@ 8:21 AM
Military and defense equipment are put to the test and subjected to uniquely harsh conditions on a daily basis. These mission-critical products must be rugged and able to withstand extreme weather and temperatures, exposed forces of gravity that are well above and beyond normal situations, and a range of contaminants such as salt, water, and fungus. Luckily, the application of a parylene conformal coating to relevant electronics can ensure that components are fit for duty in the military and defense industries.
Conformal Coatings: To Protect and Serve
A conformal coating encapsulates electronic printed circuit boards (PCBs) and other critical components to protect them from such factors as outside elements, physical damage, and hazardous chemicals. Conformal coatings also boast good dielectric properties; they protect the coated component from outside interference and signals, but also help to insulate the parts on the PCB and the etched traces from each other. This ultimately allows for a smaller board as well.
Parylene’s Unique Benefits
Conformal coatings can be made from a range of different compounds, but none has the unique benefits of parylene. Parylene is deposited as a vapor at room temperature, protecting temperature- and chemical-sensitive components from damage during the coating and curing process. It can withstand extreme temperatures. Parylene is also hydrophobic and can withstand a 100-hour salt spray test, which exceeds the MIL-STD-810F ruggedization standard.
In addition to its strength, parylene is both light and thin. It can completely permeate a space as small as 0.01 mm. The conformal coating is also pinhole-free at 0.5 microns. In military applications, where controlling component size and weight are important considerations, parylene is the most-efficient conformal coating material available.
Unlike other conformal coatings, parylene adheres mechanically, rather than chemically, to a given substrate. This attribute means that it can be used to coat a wide range of materials. And while cleaning the substrate is a key part of achieving a successful coating, the application of A-174 silane can further promote improved adhesion.
Military Coating Applications
Military electronics are frequently protected by conformal coatings. These coatings are so effective that, in many cases, they make commercial off-the-shelf components safe for use in military settings. Some real-world military applications include:
- Portable radio sets. Military radio electronics need to be extremely rugged to survive battlefield use. But at the same time, they contain sensitive digital electronics. Parylene conformal coatings protect PCBs without adding additional weight or size, keeping products as compact and lightweight as possible. Their dielectric properties also help to prevent interference and crosstalk.
- Vehicle electronics. The electronic systems in military ground vehicles are frequently protected from vibration, dust, and explosion damage by the application of parylene conformal coating.
- Aircraft lighting. As more military planes use LEDs as an efficient and long-lasting light source, they’re faced with the challenge of UV degradation. Parylene conformal coating applied with Diamond-MT’s unique process protects the LED from yellowing.
- Exposed surfaces. Optical glass, radiation sensors, and radar transmitters all benefit from the use of a parylene conformal coating to protect them from the elements. Parylene’s high strength and low permeability make the conformal coating an effective protector of exposed surfaces.
Diamond MT maintains a large, ESD-safe facility for coating sensitive military electronics and components. Our staff is trained in MIL-STDs, and we are both IPC certified for handling electronics and ITAR certified.