Parylene coating in production
Co-authors and contributors
- Dr Lee Hitchens, Nexus
- Warren Boomer, Thin Film Partners
A typical Parylene coating flow production process looks similar to a conformal coating line with a few extra areas added in. Key processes before the Parylene application are cleaning and surface preparation.
The full process is discussed below:
Work instructions preparation
A full set of work instructions are required.
This is one of the most critical process since the instructions should describe each step in simple terms including surface treatment and deposition process so that the technicians can follow to avoid major problems.
After the work instructions and other administrative tasks have been completed, the Parylene coating production process starts.
Unpacking and inspection
Once all of the items have been unpacked, they are then routed to incoming inspection.
Here, parts are counted to verify quantity as well as inspected to verify that no damage occurred to the assemblies prior to coating.
Cleaning & cleanliness testing
Parylene normally requires cleaning to ensure excellent adhesion to the circuit.
Promotion and drying
Parylene does not adhere well to many surfaces.
Adhesion promotion and surface treatment may be required using primers and other materials before application.
Parylene masking
Masking is done in accordance with the product drawings and requests for coating keep-out areas.
Once completed, the parts go into masking inspection to verify compliance with the masking drawing.
Fixture loading
The circuit boards may be hung in fixtures ready to be placed in the Parylene deposition chamber.
Parylene application
The Parylene coating is applied through a deposition process.
Parylene de-masking
Once coating has been deposited, the coated materials have the masking material removed using great care not to damage the thin layer of Parylene applied.
Final inspection
Once Parylene is applied to the parts they need to go through a final inspection.
The final inspection ensures that all previous steps were successfully completed and that the final product completely complies with the drawing and specifications.
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