Why is my conformal coating process not a waterproofing process?

This is question being asked more often today in areas such as LED applications in outside environments and automotive electronics.

Conformal coatings are meant to “conform” to the surface of the PCB. This ideally would produce a homogeneous thin film across the PCB at a uniform thickness covering all of the printed circuit board and components to the required level. In this case a PCB may be “waterproof” allowing water to not short out the electronics on the circuit board.

Unfortunately, in general liquid conformal coatings do not form a homogeneous coating film and thickness due to the fact that the coating slumps whilst drying. This is particularly prevalent at the sharp edges of a component and leads to thinly covered areas being exposed to water and creating electrical shorts when water is exposed to the circuit board.

There are ways of improving the liquid application process so the coating coverage is improved but this requires important changes in a typical application method. Another alternative is to use a vapour deposition conformal coating like parylene which conforms uniformly to all areas of the circuit board and components at a uniform thickness and thus offers true waterproofing protection.

Talk to SCH Technologies if you wish to understand your options on how you can “waterproof” your PCB or click Contact SCH.

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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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