Effect of Chip Dimension and Substrate Thickness on the Solder JointReliability of Plastic Ball Grid Array Packages

This paper presents a non‐linear numerical study to investigate the effect of chip dimension and substrate thickness on the solder joint reliability of plastic ball grid array (PBGA) packages. The package under investigation was a 225‐pin full‐grid PBGA assembly. The diagonal cross‐section of the PBGA together with the printed circuit board (PCB) was modelled by plane‐strain elements. A uniform thermal loading was applied and the solder joints were stressed due to the mismatch of coefficient of thermal expansion (CTE) and constructions of the PCB assembly. The effective stress and accumulated plastic strain of solder balls against various chip dimensions and substrate thicknesses were evaluated as an index for the reliability of solder joints. The results of this study are helpful for electronics packaging engineers to optimise the geometry of plastic ball grid array packages.