N. Helmold, P. Iyer, and C. Hillman
CALCE Electronic Products and Systems Center
University of Maryland
College Park, MD 20742
Electrically conductive adhesives have been used for many years for die mounting and terminal bonding of components in some types of hybrid circuits. In the area of isotropic conductive adhesives the preferred systems are silver filled epoxy adhesives. The interaction of silver with the finishes on the component and/or board side plays an important role in the reliability of the interconnect. This report reviews the possible failure modes in silver filled adhesives emphasizing the intermetallic formation in these systems. A silver filled adhesive was used to fix a thermistor to the base of a hermetically sealed laser module. The test specimens were subjected to 500C, 850C, 850C/85%RH, 850C, and 1250C under inert atmosphere, and the resistance changes over time were monitored. A standard lifetime prediction based on the results and work done previously is discussed.
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