Effect of Bi Content on the Microstructure and Mechanical Performance of Sn-1Ag-0.5Cu Solder Alloy

Abstract

The purpose of this work is to explore the impact of 0.5, 1.5, 2.5 and 3.5 wt.% Bi additions on the microstructure and mechanical performance of Sn-1Ag-0.5Cu solder alloy. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were utilized to examine the microstructure of the present solders. Creep measurements have been used for the preliminary assessment of mechanical properties. The steady-state creep rate, έst, diminished as the Bi’s concentration increased and reached 2.5 wt.%, with this trend altering above this point. Furthermore, increasing the aging or testing temperature caused the έst values to increment for all the investigated solders. έst variations with different Bi content and aging temperature were observed by examining the Sn-Ag-Cu solders’ structural evolutions. The mean value of the activation energy of all investigated solder alloys was found to be ∼52 kJ/mol. This value is appropriate to that quoted for the dislocation climb through the core diffusion as the dominant operating mechanism. The XRD findings supported the microstructure and lattice parameters variations with both aging temperatures and bismuth concentrations.