Conformal coatings and their increasing importance for a safe operation of electronic assemblies

Abstract

Purpose The paper aims to describe the various moisture loads affecting conformal coatings. It also seeks to differentiate these from dewing. In the case of dewing, osmotic processes may trigger completely different chemical‐physical processes on the electronic assemblies. Design/methodology/approach Numerous test methods are available to verify the climatic resistances of conformal coatings. Focussing on moisture load and dewing, the different types of load are discussed and illustrated by means of examples. Findings The tests performed to ascertain the temperature and moisture load of conformal coatings show that under these high loads the electrical functional reliability is maintained. Thus, impacts of the individual process steps can be examined and assessed by means of moisture and insulation measurements. Research limitations/implications Utilising different stress evaluations the described tests demonstrate the qualities of conformal coatings for electrical assemblies. Prospective tests for the purpose of lacquer and process qualification are presented. Originality/value The physical‐chemical load types with their consequences on conformal coatings for the protection of electrical assemblies are described.