How can I determine how much board coverage I can achieve using a conformal coating?

This is a rough formula for estimating conformal coating coverage, based entirely upon a bare, unpopulated board and does not compensate for any transfer inefficiencies, components or wastage.

Metric Calculation:

  • In one Litre there are 1,000 cubic centimetres (1ml = 1cm3).
  • 1cm = 10,000μm, therefore 25μm (approx 1 mil) = 0.0025cm.
  • To obtain the coverage, if the coating is 100% solids, you would divide the 1,000 cubic centimetres (1 litre) by 0.0025 – thereby obtaining coverage of 400,000 square centimetres at 25μm (~1 mil) thick.
  • If you are seeking a thickness of 50μm or 75 μm ( approx 2 or 3 mils) you would simply divide the 1,000 cubic centimetres by the desired thickness; i.e. 0.005 (50μm / 2 mils) = 200,000 square centimetres of coverage and 0.0075 (75μm /3 mils) = 133,333 square centimetres of coverage.

THE ABOVE ASSUMES 100% SOLIDS – TO COMPENSATE FOR THE SOLVENT LOSS YOU NEED TO MULTIPLY ANY OF THE ABOVE COVERAGE NUMBERS BY THE PERCENT OF SOLIDS CONTAINED IN THE COATING – AS FOLLOWS:

As an example Conformal Coating A is 35% solids therefore coverage at 25μm (1 mil) would be 140,000 square centimetres (400,000 x 35%), coverage at 75μm (3 mils) would be 46,667 square centimetres (133,333 x 35%). This method will work for all conformal coatings. The only variable is the percent of solids within the different coatings.

Click Contact Us to help you further or visit our Technical Database to find more help on this topic and many others.

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About Dr Lee Hitchens

Dr Hitchens has been working in the electronics industry and the area of conformal coatings for over 25 years in various areas including sales and technical support. He has also been training people for almost the same amount of time in all areas of conformal coating whether that is materials & equipment selection, process development or troubleshooting to help them solve their particular problem. Recently, he decided that the industry needed a specific place where all of the useful knowledge on conformal coatings could be collated for users to find easily and use in their own production process. So, Nexus was born and he began the Nexus eBook project.

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