Tailoring microstructure and mechanical properties of sintered Cu nanoparticles
L. Du (TU Delft - Electronic Components, Technology and Materials)
Gerald Schaffar (Montan University of Leoben)
W. Jiao (TU Delft - Electronic Components, Technology and Materials)
K. Liu (TU Delft - Team Marcel Sluiter)
R.H. Poelma (TU Delft - Electronic Components, Technology and Materials)
J. Fan (Fudan University)
Willem van Driel (TU Delft - Electronic Components, Technology and Materials)
X. Fan (Lamar University College of Engineering)
G. Zhang (TU Delft - Electronic Components, Technology and Materials)
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Abstract
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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