Characterization of Crack Growth in BGA Under Drop Impact

This paper presents the characterization of the crack growth rate of Sn-4.0wt.%Ag-0.5wt.%Cu (SAC405) solder joints under drop impact. Several actual ChipArray® BGA (CTBGA) packages were cross-sectioned, polished and used as the test vehicles. The ball drop tests were performed using a specially-designed tester. The drop impact from the drop ball induces bending in the PCB, which damages the solder joints. The crack lengths in the solder joints were measured after every five drops using microscope imaging. Crack growth rates were calculated from the test results. Insight into the crack growth rate in solder joints under drop impact is provided. The direct cyclic approach for low-cycle fatigue analysis in ABAQUS was used to simulate the crack growth in the solder joints.