Solvent Use in Parylene Deposition

Despite being well-versed in the different types of conformal coatings, many individuals mistakenly believe that the chemical vapor deposition (CVD) process for Parylene coatings involves the use of a solvent. This misconception is debunked below.

Parylene Deposition

Parylenes are polymers capable of providing resilient, dielectric, micron-thin conformal coatings for an exceptional variety of products and purposes. Their unique CVD application process deposits vaporous Parylene deep into a substrate’s surface on a molecule-by-molecule basis, generating a pinhole-free protective film that conforms to all underlying contours, regardless of shape or position. Polymerization for Parylene does not terminate chain growth during the process. This is unlike liquid coatings, where monomer and initiator are dissolved in water or an appropriate solvent, conditions that expedite the removal of heat.

Parylene, known for its chemical inertness, offers outstanding resistance to chemicals. This is achieved through a specialized chemical vapor deposition process required for substrate application. The CVD process creates films that conform perfectly to the assembly’s external shapes without the need for solvents. The resulting coatings exhibit excellent mechanical and electrical properties.

No Solvent Required

Parylene deposition, a byproduct of green polymer chemistry that minimizes the use and generation of harmful substances, utilizes the Gorham Process for CVD. Despite misconceptions, Parylene CVD does not require a solvent or catalyst and is performed in a vacuum, resulting in zero by-products. The deposition of Parylene is self-initiated and un-terminated, eliminating the need for initiators or termination groups. Although Parylene was initially identified as a derivative of para-xylene, a common solvent, the process itself is solvent-free. The historical association of Parylene with para-xylene may have led to the mistaken belief that solvents are essential for successful CVD processes.

Conclusion

In conclusion, Parylene coatings, applied through a chemical vapor deposition (CVD) process, stand out for their superior properties and the absence of solvents in their application. The unique CVD method of depositing Parylene ensures a protective layer that conforms seamlessly to all surfaces without the need for harmful substances. This green polymer chemistry approach not only enhances performance but also eliminates by-products, making it an environmentally friendly choice for diverse coating needs.