Abstract: This work aims to deeply investigate the influences of a high volume fraction of interfacial intermetallic compound (IMC) upon the shear properties and fractured surface morphologies of the Cu/Sn37Pb/Cu solder joints. We conducted the shear-fracture test, explored and analyzed the IMCs’ growths, shear strengths and fracture modes of a series of Cu/Sn37Pb/Cu solder joints which differed in reflowing time and aging time. Our experiment observed the gradual thickening and flattening of the interfacial Cu3Sn layer as well as the increasing and enlarging Kirkendall voids at the Cu3Sn/Cu interface as the aging treatment processed. The thickening of the interfacial Cu3Sn layer led to an increase → decrease trend of the joint’s shear strength, which might be attri-buted to the excessive thickness of the brittle IMC layer or the grain coarsening of Sn-rish phase and Pb-rich phase. The solder joints with shorter aging time and reflowing time had a relatively higher volume fraction of bulk solder and displayed a ductile fracture mode. However, as the aging time or reflowing time were prolonged, the fracture mode gradually changed into a ductile-brittle mixed failure mode, and to a ductile fracture mode finally.
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2018, Vol. 32 
