Materials characterization of the effect of mechanical bending on area array package interconnects

The mechanical integrity of solder joint interconnects in PWB assemblies with micro ‐ BGA, chip scale, and LGA packages are being questioned as the size and pitch decrease. Three‐point cyclic bend testing provides a useful tool for characterizing the expected mechanical cycling fatigue reliability of PWB assemblies. Cyclic bend testing is useful for characterizing bending issues in electronic assemblies such as repetitive keypad actuation in cell phone products. This paper presents the results of three‐point bend testing of PWB assemblies with fine pitch packages. The methodology of materials analyses of the metallurgy of solder interconnects following mechanical bending and thermal cycle testing is described.