Summary: | Approved for public release, distribution unlimited === By using a constant depth scratch test, the interfaces shear strength of various thin film/substrate interfaces can be determined. The ability to quantitatively ascertain when thin film debonding occurs has become especially important in the fields of electronics, optics, and protective coatings. A new model and experimental apparatus have been developed in order to more accurately determine thin film interfacial shear strength. While other tests are either qualitative in nature or experimentally difficult, the constant depth scratch test, which utilizes a Vickers microindenter for scratching a film/substrate system to debond the interface, produces quantitative results that are based upon a simple model. Since the depth is maintained constant during scratching, the complexity of the analytical formulation is reduced considerably, enabling the calculation of a numerical value for shear stress. Tests were conducted on chromium films on glass, gold thin films on aluminum nitride, and diamond films on aluminum nitride in order to determine and compare various interfacial shear strengths.
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