Adhesion studies of polyimide-epoxy interfaces in flip chip assemblies

The adhesive strength between underfill resins and organic passivation layers is controlled by the molecular interactions occurring at the interface and the plastic deformation mechanisms occurring in the underfill resin. Therefore, improvement in reliability can be realized by selecting tough underfill resins with the proper chemistry to interact with the specific organic passivation layer chosen. Surface treatment of the organic passivation coating can improve adhesion in cases were the inherent molecular interactions are weak.