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Deposition Process

Vapor Deposition

Parylene films grow molecule by molecule onto parts inside a room temperature vacuum chamber.  The vapor deposition process takes place in a closed vacuum system.    A two-step furnace heats the powder “dimer” and turns it into to a gas.  The gas enters the chamber and forms the parylene polymer when it deposits on the cooler, room temperature, surfaces in the chamber.

The gas enters the chamber as small monomers and combines to form the polymer called parylene.  Parylene transforms from a gas to a solid without a liquid phase.  The monomer gas is able to enter tiny openings and deposit without creating any stress to the part.  Parylene is an outstanding conformal coating that is pinhole free.  Parylene is used to coat the most complex structures. It has the ability to cover every nook and cranny, encapsulate complex shapes and uniformly cover sharp edges.

Parylene thickness is uniformly controlled in a range of thicknesses- from hundreds of angstroms to over a hundred microns (several mils).  The required thickness depends on the application and purpose of the coating. Typically, parts will require between 1 and 50 microns depending on the application.


Before we begin depositing parylene, we take a few steps to ensure success.  When parts arrive, we perform an incoming inspection to check for part accuracy and cleanliness. After the incoming inspection, we prepare the parts to be coated. Most parts go through an adhesion promotion process to help ensure the parylene coating bonds well with the part surface.

If there are any areas that need to remain uncoated, we mask and seal the part as needed.  Finally, the prepared parts are carefully arranged and sealed in the deposition chamber.

Coating Process

With the parts fixtured in the chamber, the deposition process can begin.  Parylene is deposited via chemical vapor deposition (CVD) at micron level thicknesses (typically 1-50 microns).


Parylene is applied to parts using the three-stage vapor deposition process shown above.

Stage 1: The solid parylene dimer – in powder form – is placed inside the vaporizer where the parylene is vaporized into a dimer gas at 150 degrees C.

Stage 2: The dimer gas then flows into the pyrolysis furnace which, at 690 degrees C, heats the dimer gas into a monomer vapor.

Stage 3: Finally, the monomer vapor enters the room-temperature coating chamber, where the parylene deposits itself molecule-by-molecule onto everything in the chamber to create a very thin and truly conformal coating.


After the parylene deposition process is completed, parts are removed and we verify the thickness by taking sample thickness measurements throughout the chamber.

After thickness verification, parts are carefully handled to expose uncoated areas as required.  Next, parts are inspected to ensure they meet customer specifications, then packaged and labeled for shipping.  Finally, coated parts along with VSI quality documentation are shipped to the customer’s facility ready for use.

Ask an Expert about your own application and let us impress you! Because each customer’s part is unique, our engineers bring their extensive experience to ensure that every part is coated to your unique specifications.  For products requiring innovative solutions, there is no better choice than VSI Parylene.