Buckling-delamination and cracking of thin titanium films under compression: Experimental and numerical studies

Estimation of interface toughness of thin films deposited on a polymer substrate remains a longstanding challenge. Ti adhesion layers are used to improve the adherence of the conducting line material. Toward this objective, we propose an approach combining a uniaxial compression test with a non-linear numerical analysis for adhesion determination of thin titanium films on polymethylmethacrylate substrates. During the test, tunneling film buckling-delamination was formed and after that, transverse film cracking across the buckle coupled with further interface delamination occurred under increasing strain due to deformation of the substrate in longitudinal direction. A three-dimensional model incorporating a cohesive zone along the film/substrate interface is then developed to simulate the process of film buckling and transverse cracking concomitant with interfacial delamination. Parameter studies of interface properties are conducted and simulation results are compared with the experimental data. It can be shown that the buckling-delamination width is dominated by mode II interface toughness (the energy release rate in tangential direction). Consistency between the experiment and the developed numerical analysis has been established, enabling the interface adhesion parameters to be ascertained.