Is Parylene Safe?

Parylene application involves utilizing a vapor deposition polymerization (VDP) process implemented under a vacuum. Unlike wet coating application methods – brushing, dipping, spraying, etc. – Parylene VDP is not line-of-sight. Because the gaseous monomer envelopes all sides of the assembly being coated, appropriate process control allows vacuum deposition of a uniquely conformal coating, one that penetrates deep into any crevices, rivulets, or sharp edges and points that can exist on an assembly’s surface. The resultant Parylene film is insulating, ultra-thin and pinhole-free, exhibiting superior protective barrier qualities and very low moisture permeability.

Among many others, these properties distinguish Parylene as a conformal coating compared to liquid coatings such as acrylic, epoxy, silicone and urethane. Exceptionally stable biologically, chemically and electrically, Parylene’s versatility recommends its usage for a wide range of products and purposes, including aeronautic, automotive, consumer, electronic, medical and military, even encompassing micro-electrical-mechanical systems (MEMs) and nanotechnologies. Nevertheless, it is always necessary to establish Parylene’s capacity for prolonged, safe-use for whatever coating application it is directed to.

Consumer Safety of Parylene-coated Products

One category of products where Parylene coatings are integral to the product is implantable medical instruments, such as blood pressure sensors and cardiac-assist devices like pacemakers. Other medical devices benefitting from Parylene film protection include:

• Brain probes
• Bone-growth stimulators
• Neurostimulation systems
• Neurosensing/locating technologies
• Bone pins
• Point-of-care diagnostic systems
• Stents
• Electronic circuits
• Electrosurgical and powered surgical tools
• Injection needles
• Mandrels
• Prosthetic components
• Orthopedic devices
• Sensors for diagnostic monitoring of patients’ conditions
• Ultrasonic transducers.

Consumer safety is carefully scrutinized because the devices themselves maintain operation in conditions where reliable functionality may be necessary to sustain the patient’s life. Parylene coatings protect the body from the device (biocompatible), while safeguarding the device itself from often harsh bodily fluids (biostable).

Parylene provides an effective electrical insulator that will not degrade in the presence of electrical current. It resists solvents and is insoluble at temperatures to 450°C. These factors generate reliable consumer safety under most performance circumstances, for the vast majority of uses.

Biocompatible, Parylene possesses no pigment, antioxidants or other additives that might:

• Irritate or infect internal tissues or organs
• Leak into the human system during application and interfere with medical instruments’ measurements or readings

Moreover, Parylene’s ultra-thin, dielectric properties can usefully be applied to MEMS or nano medical technologies, designed for use in less accessible, more-constricted body regions. Implantables coated with Parylene have repeatedly demonstrated their reliable utility for function-focused internalized medical devices. Ultra-thin Parylene coating layers provide superior component protection, adding only minimal mass to the device, which allows components to be safely situated in difficult to access regions of the body. Parylene-protected implants assure the lowest level of negative and potentially infectious surface-to-tissue interaction of any currently available conformal coating.

In addition to its utility for coating medical devices, Parylene’s reliable combination of adhesion, electrical insulation, durability and flexibility augments consumer safety for other products:

• Aerospace/military: Escalating application of commercial off-the-shelf (COTS) electronics for aerospace/military systems is made safer by use of Parylene coatings, which enhance functionality for embedded on-site weaponry, manned spaceflight/satellite electronics, and radar/detection equipment.
• Automotive: Parylene protects automotive circuits from engine environments typified by ongoing contact with harsh automotive fluids, engine humidity, exhaust fumes and fuel and electrical current. It additionally helps maintain sensor functionality when subject to changes in engine conditions, improving consumer safety.

Conclusion

In all, Parylene coatings are chosen for a wide range of both consumer and specialized products because they generate consistently reliable protection, shielding and protecting components without diminishing their functionality. In this way they add significant value and consumer safety.