Microstructure of Sn-1Ag-0.5Cu solder alloy bearing Fe under salt spray test

Understanding the behavior of lead-free solder alloys within a high humidity environment is a serious topic in the deployment of products in various electronics applications. The work reported herein investigates this specific impact on Sn-1.0Ag-0.5Cu-0.5Fe solder alloy. Specimens were treated with 5% NaCl salt spray. All specimens showed strong resistance to corrosion. Microstructural deformations after the test were analyzed using Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDX). Concerns were at the localized corroded area, as this would cause significant degradation at the solder joints. The mechanisms leading to these disadvantageous results as well as the microstructural evolution and correlation with the intrinsic properties of the solder alloy are discussed.