Trimodal mediated superior sintering and fracture resistance mechanism in nano-metal interconnection

• First multi-step MD elucidation of trimodal-sized nano-metal sintering mechanisms. • Pressure-size synergy governs densification physics in trimodal-sized systems. • Discovery of a novel size-dependent defect physics in trimodal-sized systems. • Small-particle controlled fracture physics enables superior mechanical integrity. Understanding the densification mechanisms and mechanical failure behavior of trimodal-sized nano-metal materials under pressure-assisted sintering is critical for developing high-reliability interconnects in advanced power electronics packaging. This paper presents a systematic atomic-scale investigation using multi-step molecular dynamics simulations to reveal the underlying mechanisms by which multimodal architectures govern sintering kinetics and mechanical performance. Results demonstrate that pressure drives atomic migration, while medium and small particles fill interstices between large ones, forming hierarchical structures. Temperature complements pressure, with thermal activation dominating at high temperatures to achieve dense states. During uniaxial tension, the system with a high proportion of small-sized particles exhibits excellent strength. Pressure-driven pore closure enhances Young’s modulus, while the fine particles sintered at triple junctions and interstitial sites form a continuous, densely packed network that physically constrains the motion and deformation of the larger particles during tensile loading. This work established a comprehensive mechanistic understanding of how trimodal particle size distributions govern sintering densification and mechanical failure in nano-metal systems, offering fundamental design criteria for tailoring mechanical properties including strength, toughness, and damage tolerance.