The intermetallic compound （IMC） formed at the interface between solder and substrate has a significant effect on the reliability of interconnection solder. The evolution of interfacial IMC in Sn-0.3Ag-0.7Cu/Cu solder joint and its effect on the mechanical properties were investigated under the different processing parameters including reflowing temperature

reflowing number and reflowing time

meanwhile

the fracture mechanism was also evaluated. The results indicate that IMC （η-Cu6Sn5） morphology is transformed from scallop-shaped to lath-shaped with the increase of reflowing time and temperature

and η phase dissolved into the solder position can be observed. With increasing in the reflowing time at 265 ℃

the η phase is grown increasingly with the decrease of grains. The growth rate of the interfacial IMC follows index power rules and its growth exponent is 0.339. It is also shown that the influence of the reflowing number on the shear strength is first increased and then decreased

and fracture mechanism is changed from pure shear fracture to micro-pore gathering fracture and then to partial brittle failure.