Microstructural and mechanical anisotropy in pressure-assisted sintered copper nanoparticles
Journal article, 2025

The mechanical strength of sintered nanoparticles (NPs) limits their application in advanced electronics packaging. In this study, we explore the anisotropy in the microstructure and mechanical properties of sintered copper (Cu) NPs by combining experimental techniques with molecular dynamics (MD) simulations. We establish a clear relationship between processing conditions, microstructural evolution, and resulting properties in pressure-assisted sintering of Cu NPs. Our findings reveal that pressure-assisted sintering induces significant anisotropy in the microstructure, as evidenced by variations in areal relative density and the orientation distribution of necks formed during sintering. Specifically, along the direction of applied pressure, the microstructure exhibits reduced variation in areal relative density and a higher prevalence of necks with favorable orientations. The resulting anisotropic mechanical properties, with significantly higher strength along the pressure direction compared to other directions, are demonstrated through micro-cantilever bending tests and tensile simulations. This anisotropy is further explained by the combined effects of strain localization (influenced by areal relative density) and the failure modes of necks (determined by their orientation relative to the loading direction). This work provides valuable insights into the analysis of sintered NPs microstructures and offers guidance for optimizing the sintering process.

Sintered Cu nanoparticles

3D reconstruction

Molecular dynamics simulation

Anisotropy

Micro-cantilever bending tests

Author

Leiming Du

Delft University of Technology

Kai Liu

Delft University of Technology

Dong Hu

Delft University of Technology

Olof Bäcke

Chalmers, Physics, Microstructure Physics

Xiao Hu

Delft University of Technology

Xinrui Ji

Delft University of Technology

Jiajie Fan

Fudan University

René H. Poelma

NEXPERIA BV

Magnus Hörnqvist Colliander

Chalmers, Physics, Microstructure Physics

Guo Qi Zhang

Delft University of Technology

Acta Materialia

1359-6454 (ISSN)

Vol. 287 120772

Subject Categories (SSIF 2025)

Materials Chemistry

Metallurgy and Metallic Materials

Other Materials Engineering

DOI

10.1016/j.actamat.2025.120772

More information

Latest update

2/19/2025