An In Situ Experimental‐Numerical Approach for Characterization and Prediction of Interface Delamination: Application to CuLF‐MCE Systems

Abstract

Prevention of delamination failures by improved design calls for accurate characterization and prediction of mixed‐mode interface delamination. In this paper, a combined in situ experimental‐numerical approach is presented to fully characterize the interface behavior for delamination prediction. The approach is demonstrated on two types of industrially‐relevant interface samples – coated copper lead frame‐black molding compound epoxy and uncoated copper lead frame‐white molding compound epoxy, – for which the delamination behavior is characterized in detail using a miniaturized in situ SEM mixed‐mode bending setup and simulated using a newly developed self‐adaptive cohesive zone (CZ) finite element framework. To this end, mixed‐mode load‐displacement responses, fracture toughness versus mode angle trends, and real‐time microscopic observations of the delamination front are analyzed to determine all CZ parameters. The various simulation results are found to be in agreement with experiments for the range of mode mixities accessible, demonstrating the ability of the characterization procedure to accurately obtain the cohesive properties of different interfaces, as well as the stability and efficiency of the self‐adaptive CZ framework.

Potential-based constitutive models for cohesive interfaces: Theory, implementation and examples

“…13(a)). Again, the results obtained for the damage SD-CZM are in very good accordance with the numerical outcome from Kolluri et al [36], and, more importantly, a good agreement with experimental data is found in the whole range of loading positions.…”

“…Bi-layer specimens with a length of 35 mm and a width of 5 mm have been used, where the thicknesses of the upper (CuLF) layer and the lower (MCE) layer were 0:2 mm and 0:5 mm, respectively. In Kolluri et al [36] and Samimi et al [37], the experimental data from Kolluri et al [25] were compared to numerical results from FE simulations of the MMMB test, where a self-adaptive cohesive zone framework was employed. While a Smith-Ferrante cohesive zone law was used for the FE simulations in Kolluri et al [36], the improved Xu and Needleman model of van den Bosch et al [24] was deployed by Samimi et al [37].…”

“…With regard to the mode I experiment, the damage SD-CZM can provide an even better prediction than the improved Xu and Needleman law. For the two loading positions f ¼ 0:00 and f ¼ 0:40, also numerical results obtained with a Smith-Ferrante CZM are available from Kolluri et al [36] (not shown). These are very similar to the outcome from the simulations run with the damage SD-CZM.…”

Dynamic crack propagation in a heterogeneous ceramic microstructure, insights from a cohesive model

“…Recently Kolluri et al [17] used a combined in situ experimental-numerical approach to characterize the interface behavior for delamination prediction in composites. They analyzed mixed-mode load-displacement responses, fracture toughness versus mode angle, and real-time microscopic observations of the delamination front to determine all cohesive zone parameters.…”