Analysis of shear mechanical behavior of solder joints in BGA in veneer structure and board-level structure

The shear behavior of solder joints in BGA package structure is studied by shear experiments. The mechanical properties of four solder joints with Sn-3Ag-0.5Cu, Sn-0.3Ag-0.7Cu, Sn-0.3Ag-0.7Cu-0.07La and Sn-0.3Ag-0.7Cu-0.07La-0.05Ce in the veneer and board-level structure were compared and analyzed. The results show that the shear strength of the solder joints in veneer structure is higher than that of the solder joints in board-level structure. The shear strength of the high-silver solder joints is the largest and the low-silver solder joint with rare earth element has been improved to a certain extent in veneer structure. However, the shear mechanical properties of low-silver solder joints with rare earth elements are basically equivalent to those of high-silver solder joints in board-level structure. The ductility of the low-silver solder joints is better than that of the high-silver solder joints under the same constraint conditions. In addition, for the same solder, the joints in veneer structure fracture in the bulk solder, and the joints in board-level structure fracture at the interface of the IMC and bulk solder.