Tailoring microstructure and mechanical properties of sintered Cu nanoparticles

LM Du and G Schaffar and WP Jiao and K Liu and RH Poelma and V Maier- Kiener and JJ Fan and D Kiener and WD van Driel and XJ Fan and GQ Zhang, ACTA MATERIALIA, 300, 121501 (2025).

DOI: 10.1016/j.actamat.2025.121501

This study investigates the microstructure evolution and mechanical behavior of bimodal-sized sintered copper (Cu) nanoparticles (NPs) under varying sintering pressures. Micro-pillar compression tests reveal a transition from collapse-dominated to compaction-driven deformation as sintering pressure increases. Transmission electron microscopy (TEM) and transmission Kikuchi diffraction (TKD) analyses identify a two-stage deformation mechanism-initial pore compaction followed by intragranular slip-fundamentally distinct from bulk Cu. Molecular dynamics (MD) simulations further reveal that large particles promote dislocation- mediated plasticity by accommodating intragranular slip, while small particles enhance load transfer through localized shear-compaction, together enabling uniform strain distribution and supporting the experimentally observed strain accommodation. The resulting microstructure achieves a combination of high yield strength (up to 320 MPa) and low elastic modulus (20 GPa), offering a compliant yet robust response. These findings elucidate a unique processing-structure- property relationship and provide a rational basis for designing porous metal interconnects capable of withstanding thermomechanical stresses in advanced electronic packaging.

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