For all of Parylene's strengths, it has one key drawback—Parylene's resistance to ultraviolet (UV) radiation is limited. Most formulations of Parylene gradually yellow when exposed to the kind of UV light that's produced by the sun. While this isn't a problem when Parylene gets used to conformally coat a printed circuit board that's sealed in a box, it can be a problem when a display made of Parylene-coated LEDs is installed outdoors.
Parylene Coating Blog by Diamond-MT
Parylene's benefits as a conformal coating are well known. It resists heat, cold, moisture, and pressure; salt spray, electricity, and solvents can't permeate it. And while these attributes of parylene contribute to the conformal coating's appeal, they also present distinct challenges, particularly in regards to parylene removal, rework, and repair.
The quality of a conformal coating job is directly related to the cleanliness of the substrate that is being coated. Clean substrates coat well, and contaminated ones don't. The only way to manage the problem is to inspect and clean the board or other item before applying the coating -- once it's coated, it's essentially too late.
More and more, cars aren't just made of steel, aluminum, plastic and silicon. Parylene is becoming one of the most useful tools in an automaker's arsenal. From protecting internal sensors and circuit boards to keeping LED indicator lights bright and color-accurate, Parylene conformal coatings are an important part of protecting today's sensitive automotive electronics.
It is imperative to obtain proper adhesion of the coating to the substrate in order to truly reap the benefits of parylene conformal coating. Poor parylene adhesion, after all, can negate some of parylene's most-prized properties, including corrosion resistance, chemical resistance, moisture resistance, and dielectric strength. So, it's in an engineer's best interest to understand the importance of parylene adhesion and how to obtain it.
Coronary stents are tubular medical implants that serve as a scaffold to open clogged or narrowed arteries in an effort to increase blood flow and reduce the potential for adverse cardiac events such as heart attacks. And providing critical support to these support structures is parylene conformal coating.
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.
Whether the application is a medical device, a printed circuit board (PCB), or a light-emitting diode (LED), a parylene conformal coating is typically applied to protect the product. Sometimes, however, the product actually has to be protected from the parylene conformal coating—or at least parts of it do.
Parylene conformal coating boasts a bevy of benefits and properties that make it an appealing choice for a variety of medical device applications. Chief among parylene’s advantages for medical applications, however, is that it meets USP Class VI and ISO 10993 biocompatibility requirements—a characteristic that is essential for many critical medical products and that other types of conformal coating sometimes lack.