Thin Film Interfacial Strength Characterization using Mixed Mode Bending

Nowadays, one of the trends of micrelectronic packaging is to integrate multiple funcional systems into one package, resulting in more applications of multi-materials in the form of laminated thin films or stacks. As a consequence, the number of interfaces increases. This causes tremendous mechanical problems, for instance interfacial delamination. Prediction of interface delamination is typically done using the critical energy release rate. However, interface strength is highly dependent on mode mixity. A new test setup is designed for mixed mode bending testing. It allows for measuring the stable crack growth as the function of mode mixity. The crack length, necessary for calculation of the energy release rate is measured by optical microscope and evaluated by pattern recognition software. comparing finite element result with critical energy release rate, it could be predicted whether and when the crack at the interface will propagate. The mode mixity is determined through combining expermental data with FEM simulation data.