2008 Volume 49 Issue 7 Pages 1513-1517
The impact properties of solder ball joints with Sn-Ag-Cu-Ni-Ge lead-free solders and Cu electrodes were investigated in the aged conditions at 393 K. The impact properties evaluated was compared with Sn-Ag and Sn-Ag-Cu solder joints. The impact properties of Sn-Ag-Cu-Ni-Ge joints were superior to those of Sn-Ag and Sn-Ag-Cu joints. In the cases of Sn-Ag and Sn-Ag-Cu joints, fracture mainly occurred in the intermetallic compounds (IMC) layer formed in the joint interface regardless of aging treatment. On the contrary, main fracture mode was solder fracture in as-reflow Sn-Ag-Cu-Ni-Ge joints. Although the main fracture mode gradually changed from solder fracture to IMC fracture upon aging, Sn-Ag-Cu-Ni-Ge joints had excellent impact reliability compared with Sn-Ag and Sn-Ag-Cu joints even after aging at 393 K for 1000 h.