Interface toughening in multilayered systems through compliant dissipative interlayers

Abstract

The effect on an interlayer on the toughness of an interface between a ductile thin film and an elastic substrate is investigated by finite element modeling and assessed towards experimental measurements. The model is based on an asymptotic K-field formulation relying on cohesive zone elements to simulate the fracture process. A compliant interlayer tends to increase the interface toughness by promoting plastic dissipation in the thin layer. Additional toughening can result from the development of plastic strains in the interlayer. The magnitude of these two toughening mechanisms depends on the film thickness, among other parameters. The model predictions are confirmed by comparison with wedge-opening test data performed on a multilayer composed of a thin Cu layer and a polymer interlayer embedded between two stainless steel substrates. These findings lay the foundation for the design of tougher multilayers and provide a critical assessment of 2 experimental protocols for interface toughness measurements requiring the bonding of a dummy substrate, such as used for DCB or four point bending tests.

Machine learning aided modelling of thermomechanical fatigue of solder joints in electronic component assemblies

“…The limited joint thickness imposes a constraint on the expansion of the plastic zone. Hence, the 𝛤 𝑝 term increases with thickness until a threshold, before tending to the small scale yielding value which is often smaller than the maximum 𝛤 𝑝 attained at an intermediate thickness [34,35,37].…”