Characterization of semiconductor interfaces using a modified mixed mode bending apparatus

This research deals with the experimental assessment of the strength of bi-material interfaces as a function of mode mixity, focusing on two dimensional problems. A modified mixed mode bending apparatus is designed and tested, which can be used to measure small forces involved in the delamination of semiconductor packaging materials. Using this setup, it is possible to measure interface strength over nearly the full range of mode mixities using a single specimen design. A finite element model is used to determine interface strength and mode mixity. As an example, the combined numerical-experimental procedure is applied to the interface between copper lead frame (LF) and epoxy molding compound (MCE). A remarkable result is that a double cantilever beam (DCB) test of this interface does not yield the lowest possible interface strength, meaning that it can not be used as a worst case test.