How to avoid de-wetting of conformal coating

De-wetting is the where the conformal coating material refuses to wet the surface of the circuit board that it has been applied to in an even way. The coating ends up being patchy.

The de-wetting effect tends to act locally due to local contamination.But, it can be a global affect right across the board.

 

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De-wetting of the conformal coating can be localised or all over the circuit board.

There are many causes of De-wetting in Conformal Coating.

These include contaminants such as residues and oils, and processes such as soldering and cleaning.

To find out more click conformal coating de-wetting.

Need help with your process?

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

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Nexus launch a new website for thin film technologies

To keep in line with mobile friendly sites and expand their range of coatings examined, Nexus has launched a new website to replace the current one.

Dr Lee Hitchens from Nexus explains,

No longer do engineers consider automatically using conventional liquid conformal coatings and Parylene in electronics manufacture to protect circuits.

Now, they turn to the material suppliers and say we have a problem. What can you offer us as the conventional materials don’t do the job?

So, alternative coatings are being considered and they are being taken from other industries. This is making it very confusing to the end user.

Nexus is there to bridge the gap in knowledge found with the ever changing range of coatings available to engineers.

Therefore, we had to expand the site to include other coatings to meet this need.

Why Use Nexus?

Nexus are here to help you understand all the different conventional and new thin film coatings available right now that could work well in protecting your product.

Everyone understands that technology industries are changing at a rapid pace.

However, what is less clear is that the requirements for a particular protective coating on a certain product are becoming less defined.

Boundaries are blurring and coatings can be used in a much wider variety of ways to protect the devices in the field.

Nexus can help bridge the gap in knowledge by explaining the different coatings available, how they are being used in new novel applications, and show how these materials could be used to provide protection for your projects.

Who is Nexus?

Nexus is an independent website and service providing technical information on thin film coatings that include conformal coatings, fluoropolymers, metal oxides and other ultra thin coatings, plus encapsulates and potting compounds.

These specialist materials are used to protect high value products such as circuit boards exposed to aggressive elements in the environment.

We also examine the application methods and processes involved in these coating techniques, with both a technical and commercial, practical view point.

Try out our new Website now.

What are the seven key stages of conformal coating production?

There are seven key stages when considering the conformal coating production process.

Not all stages may be used in a production line. But, each stage should be considered for use when setting up a new coating process.

The seven key stages are:

  • Cleaning
  • Priming
  • Masking
  • Application
  • De-masking
  • Drying
  • Inspection

Click the seven key stages of the conformal coating production process to find out more.

What are the critical physical properties for a conformal coating when dry?

Sticking conformal coating reduced sizeThe physical conformal coatings properties can be subdivided into three key areas.

These are:

  • Liquid
  • Process
  • Dry State

They can be further subdivided into many different individual properties dependent on the type of chemistry of the coating.

Dry State

Once the conformal coating is applied and is fully dried / cured then it will have reached its full potential physical properties. This is the dry state.

Critical properties include:

  • Edge Loss
  • Refractive Index
  • Glass Transition Temperature
  • Coefficient of Thermal Expansion
  • Temperature Gradient
  • Flammability
  • Flexibility
  • Abrasion Resistance
  • Hydrolysis Stability
  • Permeability
  • Chemical Compatibility and Resistance
  • Corrosion Resistance
  • Fungus Resistance
  • UV Stability
  • Outgassing
  • Thermal Stability
  • Thermal Shock

Click to find out more on the dry state properties of conformal coatings.

 

How to stop fisheyes creating a fail in your conformal coating process

fisheye defects found on a conformal coated circuit board
Fish eyes formed due to contamination on the circuit

In coating, a fish eye is a localised de-wetting defect.

It looks like a fish eye crater on the surface of the conformal coating.

Causes of fish eye defects in conformal coating

Fish eyes are normally caused by a contaminant on the surface prior to application of the conformal coating.

This contaminant is a substance like a silicon residue.

When coating is applied on top of the contaminant, the conformal coating is unable to adhere to the oily surface and a “fish eye” is caused.

Click to find out how to stop fish eye defects in conformal coating.