Top 10 Mistakes When Spraying Conformal Coating

It is important to protect sensitive components on your Printed Circuit Board (PCBs) with Conformal Coating and there are 5 main ways to apply conformal coatings

Spraying of conformal coating onto PCBs is one of the fastest way to cover a large volume of PCBs in the shortest amount of time. However, if not applied properly, the uneven or inadequate coverage of conformal coating can lead to a damaged circuit board. 

By learning and understanding the top 10 mistakes in spraying conformal coatings, you can ensure a clean and even coverage to protect all your PCBs. 

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Inadequate surface preparation

Not thoroughly cleaning and drying the surface of the circuit board before application can affect the coating. Any dirt, build-up or liquid will result in poor adhesion of the conformal coating and a weak protective layer.
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Incorrect material selection

Different surface materials require different types of conformal coating. Choosing the wrong material can lead to compatibility issues, such as cracking, peeling, or delamination, and inadequate protection.

Check out the different types of conformal coatings.

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Improper application technique

Applying the coating too thick or too thin, spraying from the wrong distance, or applying at the wrong angle can result in inconsistent coverage, voids, or drips.

Different type and consistency of conformal coating also requires different application methods

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Inadequate ventilation

Not having proper ventilation or airflow during the coating and drying process can slow down the curing time or affect the curing process. Harmful fumes from the conformal coating could also impact a person's health.
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Incomplete coverage

When spraying conformal coating, there could be spots that have been left out, either due to human error (manual spraying) or issues with the calibration of the spray tool (automated spraying). This will leave exposed areas that are susceptible to damage or contamination.
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During the coating process, dust, dirt, oil, and other particles from the environment can settle on the circuit board. This contamination creates an uneven surface or disrupts the layer of conformal coating, affecting the adhesion of conformal coating on the surface.
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Inadequate drying time

Handling or moving the boards before the coating has cured completely can result in smudging, cracking, or delamination.
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Improper curing

Improper curing as a result of the lack of time, improper airflow or human interference may not provide adequate protection against moisture, humidity, and other environmental factors.
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Ignoring manufacturer's instructions

Each conformal coating has its own application and curing method and even the same type of coating could have different instructions from different manufacturers. Not following the manufacturer's specific instructions can result in a poor-quality coating and inadequate protection.
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Inadequate quality control

Not performing proper quality control checks, such as visual inspection, electrical testing, or environmental testing before, during and after the application of conformal coating can create many inconsistencies. This result in defective boards and poor overall product quality.

Check out our 6 tips and tricks to dealing with conformal coatings!