Reliability Assessment of Sn-Pb and Pb-free Solder Joints under the Cyclic Bend and Shear Tests

The study conducts the reliability test of the flip chip ball grid array (FCBGA) components with both the cyclic bend tests and shear tests for three types of solder materials: the eutectic solder with compositions of Sn63Pb37, and the lead free solder with compositions of both SnAg3.0Cu0.5 and SnAg4.0Cu0.5. The final results for the cycles to failure data of different solder ball materials are plotted with the Weibull plots. It shows that the slope of the Weibull plot for the eutectic solder material is larger than that of the lead free solder materials with compositions of SnAg3.0Cu0.5 and SnAg4.0Cu0.5. This indicates that the lead free solder materials have much variation in the failed cycles during the cyclic test. It is noteworthy that the FCBGA components with SnAg3.0Cu0.5 solder have the best durability both in the cyclic bend and shear tests. Moreover, the failure mode analysis is utilized to observe the failure locations for the test component under the cyclic bend and shear tests. It is observed that the failure of the FCBGA component are either at the interface between bulk solder and the package side metal, or between the bulk solder and the printed circuit board side metal.