Parylene and Conformal Coatings
Composed of selected chemicals or polymer films, conformal coatings provide protective substrate coverings for all kinds of products. In addition to parylene, the substances acrylic, epoxy, silicone and urethane are most commonly used for conformal coating today. They can be simply applied to substrates -- by dipping, flow-coating or spraying the coating-material onto the substrate surface. Their resultant coatings typically measure between 25-75 micrometers (µm/microns) thick.
In contrast, parylene coatings are effective at significantly thinner levels, between 0.1-70 µm, making it better for use with smaller items or those with moving parts requiring more freedom to function appropriately. Its specialized vapor deposition process ensures parylene penetrates far more completely into the substrate surface, generating superior protection of product mechanisms and operation.
Parylene's other beneficial qualities include these multiple capabilities:
- Adaptability to unusual coating conditions, such as creviced-surfaces and those with exposed internal surfaces, points or sharp edges.
- Uniform, pinhole-free coverage/protection of most substrates, shielding them from potential environmental damage, at thickness-levels finer than other materials.
- Electrical insulation with low dielectric constancy and high tension strain, plus a reliable barrier against acids, caustic solutions, and water vapor.
- Non-conductive qualities that eliminate electrostatic, magnetic or radio frequency interference during operation.
- Reliable resistance to acids, bases and solvents.
- Thermal stability between -195 °C to +125°C.
The Many Uses of Parylene
Parylene provides effective conformal coatings considerably finer than competing coating substances. It generates secure and uniform coverings for most substrates, ensuring reliable performance through a variety of high-stress operating environments and performance conditions. Parylene demonstrates a remarkable capacity for providing these exceptionally thin but resilient film surface-coatings for an increasingly wide range of products, and is especially adaptable to the coating requirements of printed circuit boards (PCBs), microchips, their sensors, related components and other electrical assemblies. It has numerous uses for aerospace, automotive, consumer, industrial, light emitting diode (LED) products, medical/biocompatible purposes (implantable and wearable), microelectromechical (MEMS) functions, and military products.
Parylene consistently provides chemical, dielectric, moisture, thermal and ultraviolet (UV) protection surpassing competitors' capabilities, supporting refined, highly-focused usage for specific industrial/commercial products. This level of performance is assured under conditions of duress that might otherwise engender diminished performance or product failure.
Parylene's reliable combination of adhesion, electrical conductivity, durability, and flexibility serves an exceptional variety of functions and products:.
- Aerospace/military uses: Examples of aerospace/military applications requiring superior operative solutions are battlefield weapons systems embedded on-site, manned spaceflight/satellite electronics, and radar/detection equipment. Commercial off-the-shelf (COTS) electronics frequently used for aerospace/military applications benefit from ultra-fine but durable layers of electrically non-conductive parylene protective surfacing for reliable safeguards from exposure to corrosive elements, mechanical and thermal shock.
- Automotive applications: Parylene coatings protect automotive circuits from aggressive engine environments characterized by presence of brake/transmission fluid, engine humidity, exhaust fumes, freon, and gasoline, maintaining sensors' functionality through changes in engine conditions, sustaining their robust performance. Electronic sensors throughout the engine control the signal-processing connecting systems' for such essential vehicular functions as analytical performance-measurement of anti-lock brake control, emissions' management, and power train/chassis operations. Parylene maintains appropriate levels of long-term surface insulation resistance (SIR), while protecting electronic circuits and operating systems.
- Medical devices: Parylene protects both implantable and external medical equipment from the chemicals, fluids, and stray electrical charges circulating through the human body, ensuring sensors and systems work as designed. Its exceptional biocompatibility ensures superior component protection, durability, and device functionality. Among the medical devices parylene coatings effectively safeguard are catheters, cardiac-assist devices (CADs), cochlear devices/hearing aids, dermal drug delivery devices, electrosurgical devices (ESUs), implantable cardioverter-defibrillators (ICDs), intravascular ultrasound (IVUS), medical nanotechnology, needles/syringes, ocular devices, orthopedic devices of all kinds, pacemakers, sensors, stents, transducers, and wearable health-monitoring devices.
- MEMS' applications: MEMS devices effectively using parylene for substrate protection include Bluetooth headsets, cellphone accelerometers, differentiated sensors for a wide range of products, digital/still video cameras, interferometric modulator display (IMOD) devices, inkjet printers, notebook PCs, optical switching technology (OST), security/surveillance systems, tablets, and teleconferencing systems using MEMS' portable microphones.
- Ruggedized products: Designed for use under the most extreme and severe conditions, rugged products maintain efficient operation in environments with excessive variations in temperature, intensive vibrations, and unusual disparities of dryness or moisture. For instance, rugged laptops' electrical components are sufficiently robust and resilient to maintain expected standards of performance through extreme changes in temperature, wind velocity and similar abnormal environmental conditions. Parylene coatings are chosen because they generate consistently reliable protection, shielding components and exteriors under these conditions, without diminishing their functionality.
Parylene is adaptable to most uses, even if specialized processes and treatments must be devised to assure appropriate conformal coating for particular systems, products or projects. Ongoing evolution in industrial, MEMS, medical and parylene technologies will engender an environment of mutually beneficial development, creating further uses for parylene in the years to come.