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Interface strength and crack propagation mechanisms in sintered copper nanoparticles

Journal Article (2025)
Author(s)

Leiming Du (TU Delft - Electronic Components, Technology and Materials)

W. Jiao (TU Delft - Electronic Components, Technology and Materials)

Olof Bäcke (Chalmers University of Technology)

Magnus Hörnqvist Colliander (Chalmers University of Technology)

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 (TU Delft - Electronic Components, Technology and Materials, Lamar University College of Engineering)

G. Zhang (TU Delft - Electronic Components, Technology and Materials)

Research Group
Electronic Components, Technology and Materials
DOI related publication
https://doi.org/10.1016/j.actamat.2025.121187
More Info
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Publication Year
2025
Language
English
Research Group
Electronic Components, Technology and Materials
Volume number
296
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Abstract

This study investigates the interface strength and fracture behavior of sintered copper (Cu) nanoparticles (NPs) for all-Cu integration in advanced microelectronics packaging. Micro-cantilever bending tests on three configurations (Cu NP-notched, interface-notched and un-notched micro-cantilevers) were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD) and cohesive zone model (CZM). The interface-notched micro-cantilevers demonstrate superior fracture resistance, with a stress intensity factor (KQ) of 2.88±0.10 MPa m1/2, compared to 2.12±0.11 MPa m1/2 for Cu NP-notched micro-cantilevers. Simulation results, consistent with experimental results, reveal that Cu NP-notched micro-cantilevers exhibit lower fracture resistance due to porosity and stress concentrations, while interface-notched micro-cantilevers show enhanced strength, attributed to robust bonding and reduced void distribution. Un-notched micro-cantilevers display superior load-bearing capacity, with cracks bypassing the interface and propagating through porous regions. Moreover, in un-notched micro-cantilevers, a synergistic deformation mechanism is observed, where crack propagation through the sintered Cu NPs coexists with plastic slip deformation in the Cu substrate. These findings highlight the strong interfacial bonding and effective stress transfer at the Cu substrate-sintered Cu NP interface, validating the feasibility of direct sintering using Cu NPs without additional coatings.