Why use conformal coatings to protect a printed circuit board?


There are a lot of different reasons for using a conformal coating material or Parylene to protect a printed circuit board (PCB).

These reasons can include:

  • Barrier protection
  • High insulation protection
  • High moisture and humidity protection
  • Chemical and temperature resistance
  • Ruggedising
  • Improve dielectric properties
There are a lot of different reasons for using a conformal coating material to protect a circuit board including barrier protection, increased insulation resistance, chemical protection and increased dielectric properties

Barrier protection

A conformal coating can create a barrier against attack during the lifetime of the circuit board.

The coating material can prevent various types of particulate contamination reaching the surface of the circuit board, which can lead to problems such as corrosion.

High insulation protection

Conformal coatings can provide a high degree of insulation protection for the circuit board during its lifetime when applied as a protective lacquer.

The circuit board normally starts with a high level of insulation when it is first manufacture as it is normally clean.

However, with time in the field and its natural environment the circuit can degrade in different ways.

The conformal coating can slow this degradation down.

High moisture and humidity protection

Printed circuit boards can be vulnerable to moisture and humidity whilst in the field during its lifetime.

Most conformal coatings are highly resistant to moisture and humidity and this can lead to a reduction in leakage currents, cross talk, electrochemical migration, dendrite growth and arcing across the circuit board.

Chemical and temperature resistance

Some conformal coatings can be highly resistant to many types of solvents, chemical attack and be heat resistant.

Normally, a circuit board exposed to chemically aggressive environment would be attacked but the conformal coating can slow down the effects or even prevent them.


Conformal coating can prevent damage from rough handling, installation and reduction of mechanical and thermal stress.

Improved dielectric properties

Just as the conformal coating can protect the circuit from moisture it can also help to increase the dielectric strength on the circuit board between components and lead interconnects.

This enables the design of the PCB to be more compact and small.

Need to find out more?

For further information on using conformal coatings then contact us directly.

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.


Five key facts about ultra-thin, nano- coatings used in electronics protection

  1. Water repelling (hydrophobic) Properties – An ultra-thin coating is normally hydrophobic. This is because it is normally a fluoropolymer technology. The coating does not allow the water to wet on the on the surface of the coating. It modifies the surface and changes its dyne energy. A typical conformal coating like an acrylic or polyurethane is not water repellent and water wets the surface. nano coating
  2. Ultra-thin –Typical coating thickness is 1-2um for a coating (depending on application) compared to the acrylic, urethane and silicone conformal coatings that are applied at >25um.
  3. No masking of connectors required – The circuit board can be completely submerged in the coating liquid with no masking applied. Due to the extremely thin coating applied (<1-2um), the components can be connected together and the electrical connection is easily made. This would not be possible for a standard conformal coating. So, costs of processing are extremely low.
  4. Simple application process – The ultra-thin coating can be applied by dip, brush or spray.  But, the simplest method is dipping. Since there is no masking then the dip process is simple and is an extremely cost effective application method.
  5. Fast drying – Since the coating is ultra-thin and the solvents normally used are fast drying then the fluoropolymer coating dries extremely quickly. The coating can be dry in seconds and ready for use in a few minutes.

Need to find out more?

For further information on the ultra-thin, nano- coatings then contact us directly.

Or, you can go to our free eBook by clicking fluoropolymer coating materials now.

If you are new to Nexus and our work on conformal coatings then a good place to go is our Start Here page.


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.

water repelled from a connector due to FC coating square crop
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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Conformal Coating FIRST AID….Be Ready for Conformal Coating Problems Now

Be ready for process problems NOW

Conformal Coating FIRST AID….

Having an in-house conformal coating expert available to stop problems occurring or when problems occur deal with the issues is very expensive in today’s economic world.

Nexus can offer Support Contracts which can include

  • Full onsite assessment of the current conformal coating and other influencing processes with full risk analysis
  • Immediate help when problems do occur in solving the issues

Twelve Month Conformal Coating Support Contracts offered by Nexus are available here