Parylene Coating Process: Explanation, Illustrations, Pros & Cons

Dimer is loaded into a vacuum chamber to sublimate into a gas without transitioning into a liquid state.

After sublimation, the dimer gas passes through to the next stage of the deposition process by flowing through a pyrolysis chamber.

The gas will be heated to a temperature range of 500 to 700° C to split the dimer molecules and create a monomer vapor.

The monomer vapor is then drawn into a depressurized chamber, creating a vacuum.

The chamber, held at room temperature, polymerizes the monomer vapor, conformally coating all surfaces it lands on, including edges, crevices, and other topography.

The vacuum pump that draws the Parylene vapor into the deposition chamber also pulls the gas exiting the chamber into a cold trap.

This cold trap will solidify the Parylene for proper disposal.

Cleanliness

Surface Preparation

Adhesion Promotion

Masking

Demasking

Parylene Coating Inspection

Delamination

Rework

Long Run Times

How long does Parylene Coating Take?

The answer is that it depends. Parylene types have unique chemical compositions that affect the deposition process. For example, Parylene N deposits more slowly than Parylene C. Additionally, D deposits faster than C, but it can be more challenging to control uniformity within the coating chamber. Parylene film thickness is another variable. Thinner coatings entail shorter coating times.

There are multiple issues to balance when trying to speed the Parylene deposition rate, such as:

Increasing the deposition rate
Decreasing the coating time
Ensuring coating thickness uniformity throughout the chamber
Ensuring coating quality throughout the chamber

Silicone

Machine Spray Method

Parylene

Vacuum Deposition Method

Because Parylene deposits as a vapor that wraps around components, even at tight corners, with minimal changes in thickness, ensuring superior coverage compared to traditional conformal coatings.

Silicone coating has been applied in the accompanied image with uneven coverage. The darker surfaces show where the film has settled, while the lighter edges on each of the leads show where it is thinly applied. Parylene is wrapped completely around the part on the right, with even thickness all around.

Parylene Coating with HZO

Despite the many benefits of CVD, the Parylene coating process can present challenges for OEMs who need to ramp up to mass production or cut costs, but this does not have to be the case.

HZO is a Parylene supplier serving all industries with high throughput, turnkey coating solutions that decrease cost and improve quality and speed. Please visit our services page, contact us with questions, or get a quote.

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