The study of Sn-0.3Ag-0.7Cu and Sn-1.0Ag-0.5Cu solder joint reliability under board level drop impact

The reliability of Sn-0.3Ag-0.7Cu (SAC0307) and Sn-1.0Ag-0.5Cu (SAC105) solder joint under drop impact were researched. SAC0307 have a finer Ag3Sn precipitates, thinner IMC layer, and high fraction of primary β-Sn phase than SAC 105. The average IMC thickness of SAC 0307 is 2.9μm and SAC105 is 3.7μm. Both SAC0307 and SAC105 has a similar failure mode. The failed samples were categorized into four modes: (1) the whole crack through the IMC layer, (2) bonging pad fracture, (3) the crack initiate from IMC layer and propagate through void, (4) the crack initiate from IMC layer and voids, propagate through IMC and bulk solder. The conditional probability density distribution surface (CPDDS) revealed that the SAC0307 solder joint showed better performance than those of SAC 105 under drop impact. The scattering of SAC0307 drop times large than SAC105.