Thin films used in semiconductor interconnects and packaging are routinely subjected to complex loading conditions, causing serious stress during deposition and thermal cycles. These stress states often drive complex deformation modes including warpage, cracking, delamination and failure in advanced electronic devices. Conventional continuum plasticity models, while useful, fall short in capturing the fundamental dislocation–mediated mechanisms that govern plastic deformation and defect accumulation under such conditions.
In this study, we employ three–dimensional dislocation dynamics (DD) simulations to investigate the plastic response of thin–film geometries under bending–type inhomogeneous loading. The simulations explicitly capture the generation and motion of geometrically necessary dislocations (GNDs), which accommodate plastic strain gradients and govern size–dependent plasticity. In our results, the energetic nature of GNDs, long debated in strain gradient plasticity (SGP), is directly observed. In particular, bending–unloading responses reveal recoverable plastic work with a clear size dependence. Moreover, under non–proportional loading with abrupt passivation, plastic flow persists with significant hardening, an observation that substantiates the energetic nature of SGP. These insights establish a physics–based framework for predicting and mitigating bending–induced failures in advanced packaging