The low-temperature sintering mechanism and high interconnection performance of pure silver nanowire films

Abstract

Nano-silver materials are critical for advanced packaging due to their low-temperature sinter ability and high-temperature stability, effectively resolving heat dissipation and reliability issues in high-power and third-generation semiconductor devices. However, conventional silver pastes suffer from high organic content, limited thermal conductivity, and low shear strength. To overcome these limitations, this study proposes a high-performance interconnect material based on pure silver nanowires (AgNWs). By controlling nucleation conditions, AgNWs with three diameters, 40 nm, 60 nm, and 80 nm, were synthesized and processed into organic additive-free silver films. Through thermal analysis, microstructural characterization, and performance testing, the influence of nanowire diameter on sintering kinetics, structural evolution, and final properties was systematically investigated. Experimental results demonstrate that thinner AgNWs (40 nm) exhibit superior low-temperature sintering activity, characterized by a lower initial sintering temperature (193 ℃) and apparent sintering activation energy (71 kJ·mol⁻¹). The sintering of the AgNW films undergoes distinct stages: neck formation, spheroidization and transformation into a beaded structure driven by Rayleigh instability, and coarsening dominated by Ostwald ripening, with atomic migration primarily governed by surface diffusion. Thinner AgNWs favor achieving high electrical/thermal conductivity (thermal conductivity of Film 40 >300 W·m⁻¹·K⁻¹), while thicker AgNWs contribute to constructing high-strength connections (shear strength of Film 60/80 >100 MPa). The prepared AgNW films contain an extremely low removable organic residue (<0.5%), effectively avoiding the hindrance of organics during sintering and their detrimental effects on final performance, thereby enabling high-strength and high-thermal-conductivity interconnects. This study offers new insights into understanding the sintering behavior of one-dimensional silver nanomaterials, providing a novel material option for developing advanced electrical packaging and interconnect technologies suitable for high-temperature, high-power, and large-scale devices.