Co-Authors and contributors
- Dr Lee Hitchens, Nexus
Fluoropolymer Surface Modifiers (FC) are ultra thin coatings that are normally applied at a few microns in thickness although they can be applied as much thicker coatings.
The surface modifiers do a different job to the liquid coatings.
What fluoropolymer coatings do is effectively change the surface energy of the substrate they are applied to. This change in energy makes it harder for liquids like water and oils to wet the surface and cause corrosion.
Fluoropolymers in Use
The main advantage of using the ultra thin surface modifiers compared to the standard conformal coatings is that since this type of coating is so thin it generally is not necessary to use masking.
This is because the mechanical action of connecting the components together normally removes the very thin coating and good electrical connections are made.
Also an important point to realise is that no coating manufacturer of surface modifiers will guarantee that you do not need to mask the connectors.
Types of Fluoropolymer Surface Modifiers
There are several variations in ultra thin conformal coatings out in the market now but two of the most popular types are Liquid Materials and Partial Vacuum Deposited Materials.
- Liquid Materials which dry onto the substrate.
- These fluorochemical polymer coatings are generally suspended in an fluorinated solvents.
- They are non-flammable, generally low toxicity and not VOCs (Volatile Organic Compounds).
- Their concentration is in the region of 1-2% solids.
- The surface modifier can be spray, dipped or brushed. But, the preferred method is dipping since one of the most important advantages highlighted by the manufacturers of these coatings is that in general you don’t need to mask the components.
Partial Vacuum Deposited Materials
- Partial Vacuum Deposited Materials are applied in a partial vacuum deposition.
- The coating is deposited onto the surface in a gaseous state.
- The monomer (coating before it joins together) is released as a gas into the chamber.
- The monomer forms covalent bonds with the free radical sites as the coating loves to stick to clean sites.
- The coating polymerises (the small monomers join together to make very long molecules called polymers) and forms the hydrophobic layer.
- The chamber is brought back to room temperature and the substrate is coated.
Further information can be found by clicking Alternative Coatings: Surface Modifiers