Metallographic cross sections and scanning electron microscopy as analytical tools in the failure analysis of rectifiers

The use of metallography for the assessment of the integrity of the ohmic bond of rectifiers has been investigated. With care, good cross sections can be prepared. However, the integrity of the silicon to metal contact bond cannot be reliably estimated from a two-dimensional section. Scanning electron microscopy was found to be less susceptible to ambiguities as a result of specimen preparation. The depth of field of SEM micrographs permits a clear identification of the ohmic contact.