An investigation of reliability of solder joints in microelectronic packages by high temperature moiré method

In this study, novel high temperature moiré interferometry was applied to assess the long-term reliability of solder joints in Ball Grid Array (BGA) packages. Actual in situ deformation of the solder joints was measured as the joints were subjected to thermal loading and unloading processes. Quantitative strain analysis provided subtle details on shear strain concentrations at multi-material junctures and within interconnections. The measured thermal deformation was then substituted into fatigue models, which enabled the fatigue lives of the packages to be predicted. Comparisons between performances of the eutectic (63 wt%Sn/37 wt%Pb) and Pb-free SAC387 (95.5 wt%Sn/3.8 wt%Ag/0.7 wt%Cu) solder joints were made on individual components. The size effect on the reliability of the Sn–37Pb package, and the Coefficients of Thermal Expansion (CTE) of different materials in a BGA package including FR-4 PCB (Printed Circuit Board) Laminate solder joints were also investigated. These results were compared to previous reports from literature, and comprehensive discussions were provided.