Effects of ball pad configuration on joint reliability in BGA chip-scale packages

The drive for thinner, lighter, smaller semiconductor packages has produced not only a variety of advanced package configurations but numerous packaging concerns, including joint reliability, moisture-induced reliability, warpage, and coplanarity. One critical concern is the joint reliability of unique ball pad configurations in chip-scale packages (CSPs) rendered by the advancement of the microvia technologies. This study examines the effects of ball pad configurations on solder joint integrity and reliability, with its focus on a conventional pad versus a via-defined pad configuration on bismaleimide triazine (BT) and flex interposers. The assessment of board-level reliability was correlated to solder ball shear tests and a simplified analytical model for further insights into the failure mechanism.