The science behind fluoropolymer coatings for protecting electronic circuit boards

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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.

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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.

A NEW family of high-performance fluorochemistries customized to meet the toughest challenges from Thin Film Partners

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Ultra-thin OPX features superior protection is ideal for display screens on cell phones and tablets. The fluoropolymer keeps your display free of smudges and fingerprints.

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Why hybrid processing of traditional conformal coatings and fluoropolymer, nanocoatings could improve your reliability

Traditional conformal coatings protect the circuit well if they are selected correctly. However, where the coating is not applied there is little or no protection.

Nano coatings (FC), ultra thin coatings of thickness <2μm, provide hydrophobic properties and don’t need masking.

The lack of need for masking is due to the coating thickness being so thin that there is no resistance to removing the material. This means the FC can coat all of the circuit including connectors and offer the protection of the coating.

However, this very fact means the FC coating is delicate to handle and may not provide the long term reliability needed like a traditional coating.

So, what if we could combine the two materials and have the properties of both?

The circuit board would have:

  • The long term protection due the traditional conformal coating
  • The hydrophobic nature due to the FC coating
  • Protection all across the circuit board

Nexus have been experimenting wth dual coating with both traditional conformal coatings and ultra-thin coatings.

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A circuit board with both conformal coating and a fluoropolymer (FC) coating applied. The FC material in the connector repels the water droplet that would normally capillary into the component.

The results are extremely interesting for potentially increasing the protection of the circuit without adding a significant amount of cost to the process.

To find out more read the Nexus Article The Rise of the Hybrid Conformal Coating to find out.

Need help with your process?

Contact us at Nexus and we can help solve your issues.

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