The Finite Element Model of the Effect of the Interface Behavior of Corner Bond on the Reliability of the BGA Package under Thermal Cycling

As the scale of packages is increasing with the integrated devices on board, the stress, strain and damage induced by CTE (coefficient of thermal expansion) mismatch of package and substrate board dramatically enlarges during the process of thermal cycling test. Corner bond is a solution for the package performance since it can reduce the deformation of the system. In this work, the effect of interface behavior between the polymer material of the corner bond and the solder ball on the package reliability under a cyclic temperature loading was studied and demonstrated by a finite element model. The results show that a perfect bonding mechanism between the interfaces introduces another CTE mismatch followed by increasing stress and damage, while smooth interface behavior could avoid the issue by allowing for free deformation. This work offers suggestion on material selection and process design for the corner bond of BGA package.