Comparison of dynamic and quasi-static measurements of thin film adhesion

Abstract

Adhesive failure and the attendant delamination of a thin film on a substrate is controlled by the fracture energy required to propagate a crack along the interface. Numerous testing protocols have been introduced to characterize this critical property, but are limited by difficulties associated with applying precise loads, introducing well-defined pre-cracks, tedious sample preparation and complex analysis of plastic deformation in the films. The quasi-static four-point bend test is widely accepted in the microelectronics industry as the standard for measuring adhesion properties for a range of multilayer thin film systems. Dynamic delamination methods, which use laser-induced stress waves to rapidly load the thin film interface, have recently been offered as an alternative method for extracting interfacial fracture energy. In this work, the interfacial fracture energy of an aluminium (Al) thin film on a silicon (Si) substrate is determined for a range of dynamic loading conditions and compared with values measured under quasi-static conditions in a four-point bend test. Controlled dynamic delamination of the Al/Si interface is achieved by efficient conversion of the kinetic energy associated with a laser-induced stress wave into fracture energy. By varying the laser fluence, the fracture energy is investigated over a range of stress pulse amplitudes and velocities. For lower amplitudes of the stress wave, the fracture energy is nearly constant and compares favourably with the critical fracture energy obtained using the four-point bend technique, about 2.5 J m−2. As the pulse amplitude increases, however, a rate dependence of the dynamic fracture energy is observed. The fracture energy increases almost linearly with pulse amplitude until reaching a plateau value of about 6.0 J m−2.

Three-dimensional Voronoi model of a nacre-mimetic composite structure under impulsive loading

“…It can cause a significant reduction in the load-carrying capacity of a structure. The debonding behavior of the composite can be simulated by the Cohesive Zone Model (CZM) [37][38][39].…”

Determination of strength and debonding energy of a glass-concrete interface for encapsulation-based self-healing concrete

“…9 shows the region around the peak force produced at the beginning of the steady-state of the loading process. This peak might have several reasons, for example, as a result of nucleation of interfacial cracks in a non-precracked sample [36] or due to the formation of small cracks through the thickness that would connect the external surface of the sample with internal interfacial pre-cracks [37]. However, in the present case, this peak could be explained by the presence of some residual cement paste still existing in the 2 mm gap between glass edges (see Fig.…”

Development of Quality Control Methods for Robust and Reliable Sensor Design

“…The difference of over two orders of magnitude in the interfacial/pull-off strength stems from the interrogation area, the crack/fracture size at the onset of spallation spans less than 1 mm 2 in area as compared to the pull-off force that is averaged over an area of ≈78.5 mm 2 . Differences between the dynamic and quasi-static methods of measuring thin film adhesion have been discussed by Tran et al [33]. In this article, the fracture toughness obtained from laser spall and four-point bend tests was found to be a better metric for comparison between dynamic and quasi-static thin film adhesion testing methods.…”