Overview
Parylene is a family of polymer coatings deposited via chemical vapor deposition (CVD), offering exceptional barrier properties at micron-scale thicknesses. Developed in the 1960s, it has become critical for protecting sensitive components in demanding environments. Unlike liquid coatings, Parylene forms by molecular-level polymerization, creating conformal, pinhole-free layers. The four main commercial types—N, C, D, and HT—vary in chlorine or fluorine content to optimize performance for specific applications. Its unique deposition process enables uniform coating even on complex geometries, making it indispensable for miniature electronics and precision medical devices. The material meets stringent FDA and ISO 10993 standards for biocompatibility, further expanding its medical uses.
Physical and Chemical Properties
Parylene exhibits outstanding dielectric strength (up to 7,000 V/mil) and volume resistivity (>1×10^16 Ω·cm), outperforming most plastic coatings. It maintains stability across temperatures from -200°C to +350°C (for Parylene HT), with negligible outgassing—a key advantage for vacuum applications. The material is chemically inert, resisting acids, solvents, and bodily fluids, though Parylene C offers better moisture barrier properties than N. With a typical deposition thickness of 0.1–50 microns, Parylene adds minimal mass while providing complete substrate encapsulation. Its optical clarity (90%+ light transmission for thin films) suits applications requiring visibility, such as sensor coatings. The polymer's low friction coefficient (0.25–0.35) also benefits moving parts.
Main Applications
In electronics, Parylene protects PCBs, sensors, and MEMS devices from moisture, corrosion, and ionic contamination. Its ultra-thin profile preserves component miniaturization in smartphones, wearables, and automotive electronics. The medical industry relies on Parylene for coating implantable devices like pacemakers, stents, and neural probes due to its biocompatibility and long-term stability in vivo. Aerospace applications include satellite component insulation and atomic oxygen protection. Industrial uses range from oil/gas sensor coatings to preserving cultural artifacts. Emerging applications include flexible electronics and battery separator films, leveraging Parylene's mechanical flexibility and thermal stability.
Safety and Storage
While deposited Parylene films are biologically inert, the raw dimer (di-para-xylylene) requires careful handling. Suppliers typically provide dimer in sealed containers; storage at room temperature in dry conditions prevents premature polymerization. During CVD processing, operators must use explosion-proof equipment and ensure proper ventilation to manage monomeric gas phases. Finished Parylene-coated products require no special storage. The coating itself acts as a protective barrier, though excessive mechanical stress should be avoided to prevent film cracking. For medical devices, sterilization methods must be compatible—Parylene withstands EtO, gamma radiation, and autoclaving (type-dependent).
B2B Procurement Guide
When sourcing Parylene, clearly specify: 1) Type (N for high purity, C for moisture resistance, D for high-temperature stability, HT for extreme environments), 2) Required thickness (typically 5–25μm for electronics), and 3) Coating coverage areas (selective or full encapsulation). Reputable suppliers should provide deposition process certifications and material traceability documents. For medical applications, verify ISO 13485 compliance and request USP Class VI or ISO 10993 test reports. Consider supplier capabilities for complex part handling and masking techniques. Pricing varies significantly based on volume, part complexity, and post-coating processes like laser ablation for electrical contacts. Sample coating services are recommended before full-scale procurement.