Affiliations 

  • 1 Center of Excellence Geopolymer & Green Technology (CEGeoGTech), Universiti Malaysia Perlis (UniMAP), Jalan Kangar-Arau 02600, Perlis, Malaysia
  • 2 Institute of Materials Science and Engineering, Faculty of Mechanical Engineering, Lodz University of Technology, Stefanowskiego 1/15, 90-924 Lodz, Poland
  • 3 Synchrotron Light Research Institute, Muang District, Nakhon Ratchasima 3000, Thailand
  • 4 Department of Physics, Czestochowa University of Technology, 42-201 Czestochowa, Poland
Materials (Basel), 2021 Sep 07;14(18).
PMID: 34576358 DOI: 10.3390/ma14185134

Abstract

This manuscript reports the isothermal annealing effect on the mechanical and microstructure characteristics of Sn-0.7Cu-1.5Bi solder joints. A detailed microstructure observation was carried out, including measuring the activation energy of the intermetallic compound (IMC) layer of the solder joints. Additionally, the synchrotron µX-ray fluorescence (XRF) method was adopted to precisely explore the elemental distribution in the joints. Results indicated that the Cu6Sn5 and Cu3Sn intermetallic layers thickness at the solder/Cu interface rises with annealing time at a rate of 0.042 µm/h for Sn-0.7Cu and 0.037 µm/h for Sn-0.7Cu-1.5Bi. The IMC growth's activation energy during annealing is 48.96 kJ mol-1 for Sn-0.7Cu, while adding Bi into Sn-0.7Cu solder increased the activation energy to 55.76 kJ mol-1. The µ-XRF shows a lower Cu concentration level in Sn-0.7Cu-1.5Bi, where the Bi element was well dispersed in the β-Sn area as a result of the solid solution mechanism. The shape of the IMC layer also reconstructs from a scallop shape to a planar shape after the annealing process. The Sn-0.7Cu hardness and shear strength increased significantly with 1.5 wt.% Bi addition in reflowed and after isothermal annealing conditions.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.