Creep properties of Sn-Ag solder joints containing intermetallic particles

The creep behavior of the eutectic tin-silver joints and tin-silver composi te solder joints containing 20 vol.% of Cu6Sn5, Ni3Sn4 and FeSn2 intermetal lic reinforcements introduced by in-situ methods was investigated. These cr eep tests were carried out using single shear lap solder joints at room tem perature, 85 degreesC, and 125 degreesC. The creep resistance was similar i n magnitude for all alloys, and with increasing temperature, the stress exp onents decreased in a manner consistent with power-law breakdown behavior. The FeSn2 intermetallic reinforced composite solder was found to be the mos t creep-resistant alloy at room temperature. Creep failure was observed to occur within the solder matrix in all these solder joints. Although a detai led analysis of the processes involved was difficult because of smearing of the features in the fracture surface, there were indications of grain-boun dary separation, ductile fracture, and interfacial separation.