Parylene Coated Magnet

Ι What Is Parylene Coated Magnet?

Parylene, an ultra-thin film polymer coating, provides strong protection from moisture, corrosion, salt spray, and solvents, ensuring lasting durability across diverse applications. Parylene polymers were first discovered in the late 1940s by chemist Michael Szwarc. In 1965, William Gorham of Union Carbide devised an effective deposition process, paving the way for the commercialization of Parylene coatings.

Union Carbide advanced Parylene synthesis research and acquired NovaTran in 1984 to broaden its coating services. Today, while numerous firms provide Parylene coating services, raw material availability remains scarce. Paracyclophane precursors support Parylene types N, C, D, and other variants. Parylene coated magnet applications began with electrical insulation of soft magnetic materials, later extending to surface treatment of permanent magnets.

Magnets receive a parylene coating through a chemical vapor deposition (CVD) process, typically at a rate of about 0.002 mm per hour. The coating thickness needed can be as minimal as 0.005 mm, though it’s often increased to 0.015 mm for enhanced durability.

The process begins with solid raw dimer in a loading boat, heated in a vaporizer to 100 °C–150 °C. Under vacuum, the vaporized dimer moves into a high-temperature furnace, sublimating and breaking into monomer gas. This gas flows into a coating chamber, uniformly depositing onto the magnets. For small magnets, a barrel method ensures even coverage by tumbling them in a rotating barrel within the chamber, relying solely on surface exposure to parylene vapor, not electric charge.