A multi-scale method to investigate delamination in electronic packages

Abstract

Interfacial delamination, due to the presence of dissimilar material systems, is one of the primary concerns in an electronic package design. A number of failure criteria have been proposed to solve delamination problems with a pre-defined crack at the interface. However, in a predictive simulation of electronic package reliability, it is difficult to assign pre-defined cracks to a specific interface and to use such model as an effective vehicle in the performance evaluation of electronic packages. The present study is focused on the delamination at the epoxy molding compound (EMC)/Cu interface. A multi-scale model was built to determine the interfacial strain energy density between the EMC and copper substrate. The concept of virtual internal bond (VIB) approach was introduced to complement the interfacial layer model by providing a methodology to evaluate the interfacial material properties. The interfacial material properties were derived from atomic force microscopy (AFM) measurements using the Lennard–Jones potential. The interfacial material properties were assigned to the EMC/Cu interface to represent the interaction of the EMC with copper. The calculated interfacial strain energy density was incorporated into a strength-based failure criterion for interfacial delamination initiation.