What type of problems can you have with conformal coating?

Normally, when I am working with customers I see two types of problems.

Those are problems relating to the conformal coating process and those relating to the actual product reliability.

They are two very different issues to deal with.

Conformal coating reliability problems

Ultimately, there are many factors that can affect the short, medium and long-term reliability of a circuit board.

It is not just the conformal coating that can influence this.

However, if the conformal coating material is not correctly specified at the reliability design stage then this could be the major issue and the reason for failure.

Once the product reliability requirements have been defined as part of the conformal coating design procedure then the resulting information needs to be combined with the data from the conformal coating holistic approach.

This will ensure that the risks of a failure due to the conformal coating are minimised.

if the conformal coating material is not correctly specified at the reliability design stage then this could be the major issue and the reason for failure.
If the conformal coating material is not correctly specified at the reliability design stage then this could be the major issue and the reason for failure.

Conformal coating process problems

Typical failure mechanisms in conformal coating processing normally come from the conformal coating masking process or the application process.

Conformal coating masking failures

Failures in the masking process are generally a known quantity and easy to understand.

Adopting best practice methods for conformal coating masking can help to minimise these problems.

Masking with tape and latex 1 600
Using best masking techniques can minimise some problems found in conformal coating processing

Conformal coating application failures

Failures in the conformal coating application process are very well understood.

Typical failure mechanisms include:

  • Bubbles
  • Blushing
  • Contamination
  • Capillary Flow
  • Orange Peel
  • Shadowing
  • Cracking
  • Delamination
  • De-wetting
  • Fish Eyes

Understanding and troubleshooting why these conformal coating failures occur can quickly lead to a solution to the failure in the conformal coating process.


Need help with your conformal coating process?

Contact Nexus now and let us show you how we can help you.


Dr Lee Hitchens, Author of Nexus website and ebook

Dr Lee Hitchens is the Author of the Nexus eBook and a main contributor to Nexus.

 

Design Rules for circuits to be conformal coated by Selective Robot

Selectively coating a circuit board with a robot can be a simple process.

However, for too many designers, conformal coating is simply a part number, to be applied to circuit boards.

This failure to appreciate the subtleties of the selective robot application process can result in an un-coatable (at least as specified) assembly process.

Follow our conformal coating design rules and save time, money and pain!

Every company has its own horror stories and folk lore about the challenges faced when conformal coating an assembly to successfully meet the designer’s specification.

It is almost certain that the majority of these ‘nightmare’ scenarios could have been headed off during the design and or prototyping stages of development.

Coating close to connectors.jpeg
Trying to coat connectors right up to the base of the component is going to challenge even the best engineers. Apply some conformal coating Design Rules and avoid these problems!

The design rules for conformal coating are straightforward.

Follow them and you can save money and time in your application process.

However, if the rules are not followed, the resultant circuit board design can challenge even the most sophisticated conformal coating system and its operator to achieve the finish desired.

Find out more about Conformal Coating Design Rules for Selective Robot Systems.

What are the critical points to correctly design your conformal coated circuit board to meet the highest standards?

When designing for reliability with conformal coating then there are several important areas to consider for the product:

  • Reliability Requirements
  • Life Cycle
  • Environment
  • Materials and Parts selection
  • Electrical Effects

The purpose of the conformal coating is to protect the printed circuit board. This is to increase the circuit and product reliability.

corroded circuit board
The purpose of the coating is to protect the circuit. Understanding the key points will ensure that the coating does its job

To ensure the right level of reliability is achieved with the conformal coating then a complete understanding of the design requirements for the circuit board is critical.

This should be the starting point for most engineers when considering designing for reliability.

Click designing for reliability with conformal coating to find out more.