To ensure an optimal performance of a coating over a PCBA, cleaning the flux residues as well as all the contaminants before coating is a must. However, due to the additional costs of this cleaning step, sometimes it is not considered as an option in several markets (i.e. automotive, energy) using today's no clean materials. This paper describes the performance of several kinds of conformal coatings (acrylics, polyurethanes, UV cured) over no-clean lead free solder paste residues. The physical and chemical compatibility will be assessed using several techniques. It will be shown that several tools are necessary and complementary to anticipate the performance of conformal coatings with no-clean pastes residues due to the different kinds of coatings and pastes chemistries.
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