Recently, fluoropolymer coatings are being used more often to protect printed circuit board assemblies. This is because they have very specialized properties that are very different to traditional conformal coatings and these properties are being utilized highly effectively.
To understand these properties you have to understand what a fluoropolymer coating is made of.
Typically, the coating is comprised of fluorocarbons and characterized by carbon-fluorine bonds.
The coating itself is not susceptible to Van der Waals forces (interfacial electrostatic bonds). Therefore, the surface energy of the fluoropolymer coating is extremely low.
This means that there is no adsorption of another coating or liquid on the surface of the fluoropolymer and the coating shows the familiar, hydrophobic, non-wetting characteristics with water and oil.
This non-wetting is one of many of the key properties making them so popular.
The surface energy of the fluoropolymer coating is extremely low. There is no adsorption of water on the surface of the fluoropolymer and the coating shows the familiar, hydrophobic, non-wetting characteristics.
So, what other properties do fluoropolymer coatings have that help protect circuit boards?
Generally, fluoropolymer materials have very specialized properties.
For electronics the five key properties that are driving the interest in fluoropolymer technology are:
- Being highly hydrophobic (water repellent)
- Being extremely thin whilst still providing protection
- Having a high moisture barrier and corrosion resistance
- Having a high chemical resistance
- Having high dielectric properties
To really understand the benefits you have to look at the key difference compared to a conventional conformal coating.
The key reason for using a fluoropolymer coating in electronics: No masking required
First, consider a conformal coating applied at normal thicknesses of 25um or more.
The coating is a high insulation material. Therefore, it must not be applied to a connector or part that can be damaged or needs electrical conductivity.
Further, the conformal coating naturally has good mar resistance and it cannot be easily abraded. It is tough to the touch and not easily removed.
So, if it was applied to the wrong component it would ruin the connection.
On the reverse side, a fluoropolymer coating can be applied at 1-2um in thickness and can still show the same performance characteristics.
Further, it is also extremely soft and shows almost no mar resistance when rubbed or abraded.
This allows the fluoropolymer coating to be applied to all connectors without fear of damage as the coating is easily removed or scratched away and the electrical circuit is easily made when the mating parts are connected together.
This key parameter of not requiring masking combined with the hydrophobic nature of the material and its other key characteristics makes the fluoropolymer coatings highly desirable in protecting electronic circuit boards.
Need to find out more?
Go directly to our Nano-coating fluoropolymer section or contact us directly and we can help you.
If you are new to Nexus and our work on conformal coatings then a good place to go is our Start Here page or our free conformal coating eBook.