Loading-mode-dependent deformation mechanisms of sintered porous Cu

Abstract

Sintered porous Cu contains a heterogeneous particle-neck-pore architecture whose deformation depends strongly on loading mode. In this study, porous Cu structures prepared from small particles (184 nm) and large particles (1451 nm) were examined using micropillar compression, micro-cantilever bending, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and molecular dynamics (MD) simulations. Under compression, the large-particle structure exhibited a higher apparent elastic modulus (14.5 ± 0.9 GPa) than the small-particle structure (12.7 ± 0.5 GPa), whereas the small-particle structure showed an approximately 80% higher yield strength (364 ± 58 versus 202 ± 71 MPa). In contrast, the large-particle structure exhibited an approximately 245% higher conditional fracture toughness (5.56 ± 0.14 versus 1.61 ± 0.16 MPa⋅m^1/2) and 1270% higher total bending work (8823 ± 1245 versus 644 ± 164 pJ). Microstructural analyses revealed that the refined particle-neck network accommodated compression through distributed pore compaction, neck deformation, and dislocation accumulation, suppressing strain localization. The coarser network promoted intraparticle slip and interfacial sliding under compression, while enhancing remaining-ligament continuity and neck bridging during crack propagation. MD simulations reproduced these distinct compressive responses and defect-evolution characteristics. These findings provide guidance for optimizing particle-neck-pore architectures in reliable sintered Cu interconnects.