Corrosion mechanisms at electronic assemblies under climatic stresses

During the industrial applications electronic assemblies are exposed to extreme stresses. A high humidity in combination with contaminations can initiate corrosion mechanisms, which cause a failure of the electronic assemblies. Main components of the contaminations are flux residues after soldering proceses. During a moisture condensation of contaminated boards electrolytic mechanisms occur, which lead to a metal dissolution and to a formation of migration bridges between solder joints and conductors. The failure-rate is a function of the composition and the concentration of the:contaminations, The use of protective coatings cannot prevent the:failure of electronic assemblied during moisture condensation, because the coatings are waterpermeable. The adsorption of water leads to the formation of bubbles and delaminations of the coating.