Specific Process Knowledge/Polymer Processing/Polymer Processing/Coating/Parylene Coater

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A Parylene coater is a Chemical Vapour Deposition (CVD) system used to deposit ultra-thin, uniform, and pinhole-free Parylene polymer films on a wide variety of substrates. Unlike conventional liquid coating methods, Parylene coating is performed entirely in the vapour phase under vacuum, allowing the polymer to coat complex three-dimensional structures with excellent conformality. This process is widely used in electronics, medical devices, MEMS, aerospace, automotive, and sensor technologies because of its outstanding dielectric, moisture-barrier, and biocompatibility properties.

Working Principle

The Parylene deposition process consists of four main stages:

1. Sublimation: Solid Parylene dimer is heated (approximately 120–180°C) under vacuum to produce a vapour.
2. Pyrolysis: The vapour passes through a high-temperature furnace (650–750°C), where the dimer molecules split into reactive monomers.
3. Deposition and Polymerisation: The monomer enters a slightly heated vacuum chamber containing the substrate. The monomer condenses and polymerises directly on all exposed surfaces, forming a thin, conformal polymer coating.
4. Cold Trap: Residual monomer and by-products are captured in a cryo-cooled cold trap before reaching the vacuum pump.