For conformal coatings to perform reliably, optimal adhesion is essential. Surface variations, materials and manufacturing processes can prevent good adhesion, which may compromise the coating and, in turn, jeopardize the substrate. For long-lasting stability and performance, there are various techniques that can optimize coating adhesion.
One of the most common reasons a coating fails to adhere to the substrate is contamination. Grease, oil, detergent and other materials on the substrate need to be removed before coatings are applied. Using a solvent is often the most effective method to do this. A commonly used solvent is isopropyl alcohol (IPA); not only is IPA capable of removing a majority of contaminants, it does not leave a residue, evaporates quickly and is a less toxic alternative to most other solvents.
Surface Engineering with Plasma Activation
Plasma activation uses reactive gases, such as oxygen, hydrogen and fluorinated molecules, to modify the surface properties of a substrate through surface chemical reactions. This low-temperature process is most often used to improve the adhesion coatings to a substrate by creating functional groups that react with the molecules used for coating to ensure a strong, reliable bond.
Applying Adhesion Promoters
While conformal coatings can be applied to a host of substrates, there are some combinations of materials and coatings that benefit from the additional step of a promotion technology to ensure proper adhesion.
For optimal adhesion of Parylene coatings, specifically, organosilane molecules, including A-174 silane, are commonly used as adhesion promotors and contain two functional groups. One reacts with inorganic surfaces, such as hydroxides, while the other reacts with the organic compounds in Parylene. The separate reactions form bonds between the coating and substrate. While A-174 provides optimal adhesion to a number of substrates, AdPro Poly® and AdPro Plus® adhesion promotion technologies are available to further optimize adhesion, especially to challenging substrates such as titanium, stainless steel, gold, chromium, solder mask and many polymeric materials.
SCS’ surface engineering solutions are designed to increase the longevity and performance of your advanced innovations. To learn more about our adhesion promotion technologies, contact SCS online or call +1.317.244.1200.