Microstructural Evolution and Phase Transformation on Sn–Ag Solder Alloys under High‐Temperature Conditions Focusing on Ag₃Sn Phase

Abstract

This study investigates the microstructural and phase transformations in Sn‐Ag solder alloys under high‐temperature conditions, utilizing X‐Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Electron Backscatter Diffraction (EBSD) analyses. The research addresses the shift from lead‐based solders to lead‐free alternatives, particularly the Sn‐3.5Ag variant, to meet environmental directives. Analytical techniques were employed pre‐ and post‐controlled thermal cycling from 30°C to 180°C, aimed at emulating solder reflow processes. The XRD analysis at room temperature demonstrated pronounced crystalline peaks, suggesting a preferred orientation within the crystal structure. Additionally, the stability in peak positions (2θ values) indicated low lattice strain in the material. Upon heating, peak broadening suggested grain growth and the onset of recrystallization. SEM and EDS analyses corroborated these findings, displaying a fine‐grained, well‐distributed microstructure with a homogenous composition of Sn and Ag elements. EBSD provided insights into the orientation and texture of grains, revealing a weak to moderate texture across the phases. Post‐experiment data indicated a dominant presence of larger grains and significant variation in grain size, with an area‐weighted mean grain size of 68.47 microns and a standard deviation of 8.68 microns, this suggests significant grain growth and coarsening of the Ag3Sn intermetallic compounds. These structural evolutions have crucial implications for the mechanical properties and reliability of the solder alloy in electronic assemblies, underscoring the need for further exploration of lead‐free solder materials in the electronics industry.This article is protected by copyright. All rights reserved.