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36 DESIGN007 MAGAZINE I FEBRUARY 2021 e performance requirements of conformal coatings continue to become ever more chal- lenging as electronic assemblies are becoming smaller and smaller and subjected to increas- ingly hostile operating environments. e perfect conformal coating would retain high elasticity at both high and low temperature extremes and would maintain its properties at high temperatures with no out-gassing. It would also provide an excellent barrier to moisture, both in terms of humid environ- ments and where there is a risk of liquid water splash. It would be highly resistant to solvents and corrosive gases but be easy to remove when repairs or modifications need to be car- ried out. Ultimately, the perfect coating would be intelligent, self-applying and, of course, free of charge—but then that's a whole differ- ent ball game. In this month's column, I will revisit a couple of general enquiries we have received about "bubbling" as well as the less common appear- ance of cloudy white patches following the application of a conformal coating. Blushing Naturally, we are all aware of the many potentially problematic encounters that can occur when using conformal coatings. e usual suspects tend to be contamination lead- ing to corrosion, cracking, blistering, fisheyes, de-wetting, and so forth. However, one of the rarer problems that can occur is "blushing." If you have the misfortune of discovering that your coating isn't as clear or transparent as it should be, and instead, looks dull and cloudy white, then the chances are you have stumbled upon this particular coating issue. Avoiding 'Blushing' and 'Bubbling' in Conformal Coatings Sensible Design by Phil Kinner, ELECTROLUBE

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