Unveiling the Size Effects on Microstructure, Mechanical Properties, and Thermal Conductivity of Nano-Ag Sintered at 220-280 °C

Publication Date

2-26-2026

Document Type

Article

Publication Title

Journal of Materials Engineering and Performance

DOI

10.1007/s11665-026-13291-6

Abstract

Developing nano-Ag paste with high mechanical and thermal properties at low sintering temperatures is crucial for power electronics. However, the impact of Ag particle size on nano-Ag coarsening under various conditions remains poorly understood. This study investigates how nano-Ag particle size, sintering temperature, and compaction pressure influence the microstructure, thermal conductivity, and shear strength of Ag sandwich structure. The results demonstrate that higher sintering temperatures and pressures enhance particle densification, thereby improving both thermal conductivity and shear strength. Samples prepared with 20 nm nanoparticles generally exhibited superior thermal and mechanical properties under optimized sintering conditions, though 70 nm particles exhibited higher shear strength at lower sintering temperatures such as 220 °C. This is attributed to the high filling efficiency of the 20 nm nanoparticles and a more effective diffusion-driven solidification mechanism. Although the shear strength decreased after testing at 250 °C and after 500 h of thermal aging, it consistently remained above 30 MPa. This reduction is attributed to atomic diffusion along grain boundaries and coarsening of the sintered structure. Hot nanoindentation revealed that the 70 nm nanoparticles Ag paste achieves greater densification under various conditions, creating larger inter-particle contact areas and facilitating atomic diffusion, which accelerates coarsening. This work underlines the critical significance of particle size in balancing densification and coarsening, demonstrating the promise of tailored nano-Ag pastes for reliable die attachment in power electronics.

Funding Sponsor

Huaqiao University

Keywords

mechanical properties, microstructures, sintering mechanisms, thermal conductivity

Department

Aviation and Technology

Link to Full Text

Share

COinS