Parylene: Making a Difference Across Many Markets
Posted by Sean Horn
Friday, November 22, 2013 10:34
@ 10:34 PM
Parylene conformal coatings are used in many different industries. With their hardness, chemical inertness and ability to perfectly coat any surface, they have expanded well beyond their original military and aerospace applications. Whether it’s a protective coating for an LED or a protective shell around a coronary artery stent, the compound is found in places where you might not expect to find it.
Throughout the healthcare industry, Parylene makes devices work better, last longer and interface better with the human body. Whether it’s coating needles to help them penetrate the skin more easily or protecting a sensitive defibrillator from the salt- and chemical-laden interior of the human body, medical product makers turn to this unique chemical for their coatings. For example, stents not only use the compound to protect their intricate latticework of wires but also to control the release of drugs that coat them.
Transparent and flexible, Parylene meets the requirements of a USP Class VI plastic and can be applied as a film in layers as thin as 0.1 mil to provide pinhole-free and conformal coating, even on complex surfaces common in medical applications.
One important attribute of parylene for medical coatings is its superior dry-film lubricity, with static and dynamic coefficients of friction (in the range of 0.25 to 0.33 per ASTM D 1894) approaching those of Teflon. A typical application in this regard would be the coating of tiny lead wires, used inside flexible catheters, which must be electrically insulated, chemically protected, and capable of moving easily against the catheter surfaces in extremely tight quarters. Prosthetic components such as bone pins also benefit from the lubrication properties of parylene, and treatment of the screws and nuts used with temporary bone pins and plates can prevent seizing, corrosion, and metal fragmentation. In addition, parylene’s hydrophobic and lubricious nature can minimize residual fluid buildup on both the inner and outer surfaces of needles and other medical components, thus aiding cleanup.
One of the original applications for Parylene was coating electronics components and printed circuit boards. Its unique mix of features makes it particularly well suited for this task:
- Parylene’s dielectric properties allow it to serve as an insulator for the traces on the board. This allows manufacturers to make smaller PC boards without having to worry about crosstalk and interference.
- The unique vapor deposition method allows it to penetrate extremely small spaces — like between the pins and underneath soldered-on IC chips.
- Masking allows the compound to be deposited in a way that doesn’t cover areas that need to be open for conductivity.
Cars present a range of challenges for components. They involve exposure to extremely high levels of heat inside an engine or exhaust system, extreme cold for cars operated in northern regions and omnipresent dirt, frequently blowing past sensitive components at highway speeds.
While Parylene can protect the electronics in cars, another of its strengths is in protecting the microelectronicmechanical systems (MEMs) that are used in many sensors. Given parts that are measured in micrometers or nanometers, Parylene’s ability to protect when applied in extremely thin coatings — frequently measured in angstroms — is an excellent match for these sensitive technologies.
First used extensively in defense and aerospace applications, Parylene remains an extremely popular choice in these industries. Unlike some other coatings, the compound is extremely tough, making it able to protect components so that they can meet stringent specifications like MIL-STD-810. Here are some of its benefits:
- Hydrophobia — It repels humidity and water. It can even withstand 100 hours of salt-spray .
- Thermal endurance — It can be exposed to 176 degree temperatures without failing — for 10 years.
- Chemical resistance — Parylene resists acids, bases and solvents.
- Low weight — it is effective when applied in extremely thin coatings, making it add essentially no weight or bulk to anything using it.
Light-emitting diodes have almost magical properties. They product constant, pure light while consuming very little power and generating little heat. Unfortunately, they’re also sensitive electronic components that aren’t well suited to the harsh outdoor world. Between the abrasion damage that blowing dust can cause to a traffic light to the UV-induced yellowing of an outdoor display screen, LEDs should be used with protection. Parylene doesn’t just protect an LED’s surface, though. It can also provide light-filtering abilities that help to prevent the LED from gradually yellowing and fading.
Whatever industry your business occupies, Parylene conformal coatings can help you make better products. Contact us to learn more about how we can help you leverage this technology in your operations