When it comes to conformal coatings, adhesion is everything. A coating may offer excellent barrier protection, but if it delaminates or peels away from the surface, performance and reliability are instantly compromised. In the world of Parylene coatings, one question often raised is whether adhesion decreases as the coating thickness increases.
Understanding Parylene Deposition
Parylene is applied through a unique vapor deposition process, creating a pinhole-free, uniform layer. Unlike brush, dip, or spray coatings, this process ensures that every surface—flat, sharp-edged, or recessed—is covered evenly.
However, like all coatings, adhesion depends on both the substrate preparation and the thickness of the coating.
The Relationship Between Thickness and Adhesion
In general, thinner Parylene films (e.g., 2–5 μm) demonstrate the best adhesion because the stresses within the coating remain low. As the thickness increases—sometimes up to 50 μm or beyond—internal stresses in the polymer can build up. This may lead to reduced adhesion if the surface is not properly prepared.
The key factor is not just thickness but the surface energy and cleanliness of the substrate:
– Smooth, untreated surfaces can cause poor adhesion regardless of thickness.
– Surface activation (e.g., plasma treatment) dramatically improves adhesion across all thicknesses.
– On well-prepared surfaces, even thick Parylene coatings can achieve excellent adhesion and long-term reliability.
Best Practices for Strong Adhesion
To maintain adhesion across different thicknesses:
– Use surface pre-treatments such as plasma cleaning or adhesion promoters.
– Match coating thickness to application needs—don’t overcoat unnecessarily.
– Validate adhesion using industry standards such as cross-hatch adhesion testing (ISO 2409).
SCH Services Ltd: Expertise in Parylene Performance
At SCH Services Ltd, we understand how coating thickness impacts performance. We combine expert surface preparation with advanced deposition techniques to ensure Parylene adhesion remains strong at both thin and thick layers. Whether you require ultra-thin coatings for medical sensors or thick films for aerospace, our solutions deliver reliability without compromise.
For more information visit: https://www.conformalcoating.co.uk/parylene-coating-solutions/
