Title of Paper:Effect of Ag addition on the microstructure and distribution of second-phase particles in tin-based solder alloys

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DOI number:10.1016/j.microrel.2025.115969

Journal:Microelectronics Reliability

Key Words:Intermetallics；Solder alloys；Cu6Sn5；Microstructure

Abstract:In this study, the effect of Ag content (x = 0, 1, 2, 3 wt%) on the microstructural evolution and the distribution of second phase particles in Sn-0.7Cu-xAg were analyzed utilizing scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Morphology of second-phase particles in low-temperature fracture surfaces of Sn-3.5Ag and Sn-0.7Cu solder alloys was characterized using TEM and focused ion beam (FIB) techniques. The results demonstrated that Ag within the solder matrix significantly inhibited the formation of Cu6Sn5 intermetallic compounds (IMCs). With increasing Ag content, Cu6Sn5 particles evolved from extensive, strip-like structures to a finer, more uniform distribution. Ag3Sn particles predominantly accumulated at grain boundaries, with minimal Ag detected within the solder matrix. In contrast, Cu6Sn5 particles, along with a significant dispersion of copper (Cu) throughout the matrix, were also observed at grain boundaries. Quantitative analysis demonstrated that the suppression of Cu6Sn5 formation (assessed via Gibbs free energy calculations) reached its maximum efficacy at a critical Ag concentration of 0.17 at.%, with diminishing effects observed when Ag content exceeded 0.35 at. %.

Volume:176

Issue:115969

Translation or Not:no

Date of Publication:2026-01-01

Included Journals:SSCI