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Influence of 1.5 wt.% Bi on the Microstructure, Hardness, and Shear Strength of Sn-0.7Cu Solder Joints after Isothermal Annealing

Authors :
Mohd Izrul Izwan Ramli
Mohd Arif Anuar Mohd Salleh
Andrei Victor Sandu
Siti Farahnabilah Muhd Amli
Rita Mohd Said
Norainiza Saud
Mohd Mustafa Al Bakri Abdullah
Petrica Vizureanu
Adam Rylski
Jitrin Chaiprapa
Marcin Nabialek
Source :
Materials, Vol 14, Iss 18, p 5134 (2021)
Publication Year :
2021
Publisher :
MDPI AG, 2021.

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.

Details

Language :
English
ISSN :
19961944
Volume :
14
Issue :
18
Database :
Directory of Open Access Journals
Journal :
Materials
Publication Type :
Academic Journal
Accession number :
edsdoj.9e39417164649a608f40f52a56fe1
Document Type :
article
Full Text :
https://doi.org/10.3390/ma14185134