Integrated Computational Materials, Process and Product Engineering – IC-MPPE 2022

SAC305 (Sn–3.5 wt.% Ag–0.5 wt.% Cu) is one of the most promising alloys to replace Sn–Pb solder alloys in microelectronics packaging. During reliability testing, ball grid array (BGA) test vehicles are subjected to accelerated thermomechanical cycling in order to induce crack initiation and crack propagation. The thermomechanical behaviour of SAC305 solder balls varies widely because of the mechanically and thermally highly anisotropic properties of the Sn-matrix. The anisotropy of Sn plays a significant role in the reliability of the BGA since solder balls usually solidify as single or few-grained crystals.
The developed method workflow allows (1) the non-destructive inspection of entire BGAs for existing cracks in solder balls and (2) provides statistically relevant 3D information about the severity of the damage in each solder ball by applying semi-automatic image analysis. Therefore, primary causes for crack initiation and crack propagation in solder balls during thermomechanical fatigue testing can be gained.