Fabrication of conductive interconnects by Ag migration in Cu–Ag core-shell nanoparticles

Abstract

Fabrication of conductive nanoparticle films is observed in Cu–Ag core-shell nanoparticles by fast diffusion of Ag at 220 °C from particle surfaces, leading to the formation of sintered necks of Ag at the initial particle-particle contacts. Transmission electron microscopy showed that the necks were pure Ag and that particle surfaces away from the contacts were nearly Ag-free. The extent of neck formation is controllable by the choice of initial Ag thickness. Analysis of the thermodynamics of the Ag–Cu system and the relative diffusivities of Ag and Cu provide criteria for fabrication of other core-shell two-phase systems by the same mechanism.

Microstructure evolution during 300 °C storage of sintered Ag nanoparticles on Ag and Au substrates

“…After sintering, the joint can operate at 350°C with a corresponding homologous temperature of only 0.5. Nanoparticle sintering for high power and high temperature die attach applications have been previously reported using Ag NPs [6,8,[12][13][14][15] while sintering using Cu NPs have also been reported [16][17][18][19] although these typically require applied pressure, UV light or a reducing atmosphere for successful sintering. The present work reports on changes in shear strength and the corresponding evolution of voids and grain boundaries when a commercially available Ag NP paste is used to bond Si test die to a ceramic package with Ni/Au surface metallization, followed by storage at 300°C.…”

Morphological instability of core-shell metallic nanoparticles

“…For example, AgCo nanoalloys have been employed in the oxygen reduction in alkaline media 37 , and AgCu clusters are proposed as more efficient catalysts than the corresponding pure clusters for oxygen reduction reactions 33 . AgCu nanoalloys find application in the fabrication of Pb-free solder interconnects, that can melt at low temperatures 38 . Core-shell Au-Co nanoparticles have been proposed also for biomedical applications, such as thermal ablation therapies and drug delivery, for which the magnetic Co core is coated by a shell of Au, which is a biocompatible material that can be easily functionalized [39][40][41] .…”

Twin-induced ultra-high thermal conductivity of sintering Ag nanoparticles for high power density electronic packaging

“…Recently, various studies on sintering of Ag nanoparticles paste for bonding have been reported [1][2][3][4][5][6][7][8][9]. However, the application of Ag nanoparticles paste is still restricted by long sintering time which is about 20-30 min [1,[3][4][5][6][7] and high sintering temperature which is normally above 250 °C [1][2][3][4][5][6].…”