As the second part of a series of articles describing corrosion behavior of silver, this article presents corrosion mechanism and failure modes seen for the electronic equipment under corrosive conditions. Inherent electrical bias associated with electronics application may cause electrolytic corrosion and electrochemical migration when the surface insulation resistance of dielectrics is reduced because of moisture absorption and condensation. Even a very thin tarnishing film formed may cause degradation of electrical and electronic performance as well as optical performance. Galvanic corrosion, corrosion product creep and whisker formation are also described.

The impedance of the paint film varied depending on the environmental test. It is considered that the impedance spectrum of the coating films changed by the effects of water content in the paint film, polymer structure, and elements that penetrated the paint film. However, no clear relationship could be found between the impedance spectrum of the coating film and its internal structure. To understand the change in the impedance spectrum, we performed D-SIMS and AFM-IR analysis on the paint films after the environmental test. The results suggest that the admittance spectra may reflect the state of infracted moisture and elements into the coating films.