| Summary: | Approved for public release; distribution is unlimited. === Tin-bismuth alloys have been proposed as alternatives to lead containing solders for interconnection and packaging applications. Consequently, the interface between copper metallizations and bismuth-tin solders needs to be evaluated with respect to brittle intermetallic formation. In the binary Bi-Sn alloys both the Cu6Sn5 and Cu3Sn intermetallic phases were found at the Cu/ solder interface after exposure at 250 deg C, 300 deg C, and 350 deg C. Bi-Sn-Sb alloys were also studied and in addition to the aforementioned intermetallic compounds Cu-Sb intermetallics were found. Kinetic growth laws have been established for the intermetallics at various temperatures and solder compositions. In addition, bulk samples of the solder were tested in compression in the furnace-cooled and quenched condition. Quenching appeared to result in higher strain rate dependence. Furthermore the tin-rich compositions were more strain rate sensitive than the bismuth-rich composition.
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