Conformal coating: 5 tips for application

MD Poland works alongside its customers and Electrolube engineers to provide solutions right from the design stage. We strongly believe in co-engineering and think that this approach shortens development times, reduces costs, brings greater integration between all stages of the process and ensures better product quality.

In this article, Electrolube’s Technical Director for Conformal Coatings takes a closer look at manufacturing issues, particularly those faced by circuit designers in the early stages of a project, and provides some pointers to help you avoid common mistakes when applying conformal coatings.

Adhesion results with coatings can vary greatly even when using what appears to be the ‘same’ type of solder resist from different suppliers, and this can create unexpected problems. 

A quick and very effective solution can be to specify a surface energy of > 40 dynes/cm on incoming boards and ensure that each batch is tested and rejected if it does not meet this minimum value.

Importance of a buffer zone between coated and uncoated areas

Always leave a buffer zone. Coatings are usually liquid and, when applied, flow under the combined effects of gravity and capillary forces. 

Whether you are masking or specifically relying on selective conformal coating, you will find production significantly easier if you leave a space of at least 3 mm free between the area to be coated and the uncoated areas. This small buffer will make the production process easier.

Layout optimisation to simplify application

Try to simplify the coating process during the design phase. By simply positioning connectors and components that do not need to be coated along an edge, the coating application process will be simplified. 

This will also allow you to consider dip coating as a potential method, which can lead to faster application times and reduced costs.

Impact of component separation on coating uniformity

Understand the disadvantage of separating components. A large number of elements represents a major challenge for the coating operation due to the capillary forces present, resulting in areas without coverage and protection and, conversely, areas of excessive thickness that are often subject, for example, to stress cracking or delamination effects.

 This could lead to premature board failure. That is why it should be avoided if possible.

Difficulties related to the presence of components that are too thick

Is bigger really better? Thicker components present real challenges by creating shaded and hard-to-reach areas. Try to avoid placing thick components next to ‘must-coat’ components to minimise this.

Technical support for more effective electronic protection

The effective application of conformal coating starts with the design. These measures help prevent defects, reduce costs and improve the reliability of electronic boards. 

If you work in the electronics industry and want to ensure maximum protection for your circuits, contact the experts at MD Poland for technical support and to discover the range of Electrolube conformal coatings best suited to your needs.