Microstructure, isothermal and thermomechanical fatigue behaviour of leaded and lead-free solder joints

Mohammad Ghaleeh, Ahmad Baroutaji, Mansour Al Qubeissi

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)
13 Downloads (Pure)


The reliability of solder joints is a critical issue in the microelectronics industry. The requirement of permanent electrical and thermal connections between solder alloys and the various components of a surface mount device is dependent upon the mechanical integrity of the solder and its interfaces. Accordingly, in this paper, the reliability of lead-free, Sn-3.8Ag-0.7Cu, and leaded, Sn-37Pb, solder alloys was investigated under both thermal-mechanical fatigue (TMF) and isothermal mechanical fatigue (IF) conditions. The investigation included material characterisation and fatigue testing on 4-ball grid array (BGA) specimens. The IF tests were carried out under load control at three different temperatures including Room Temperature (RT), 35°C and 75°C. Also, a set of ‘not-in-phase’ (nIP), ‘in-phase’ (IP) and ‘out-of-phase’ (OoP) combined thermal and mechanical cycling tests were carried out to investigate the TMF behaviour of the solders. The stress-life curves for each test condition were generated and then compared taking into account the observations on microstructure. It was found that the IF and TMF performance of Sn-3.8Ag-0.7Cu alloy was better than Sn-37Pb alloy when expressed as stress-life curves. Additionally, the Sn-3.8Ag-0.7Cu was less susceptible to the changes in temperature. This study provides a comprehensive insight into the reliability of solder alloys under a wide range of loading conditions.
Original languageEnglish
Article number104846
Number of pages84
JournalEngineering Failure Analysis
Early online date11 Aug 2020
Publication statusPublished - Nov 2020

Bibliographical note

NOTICE: this is the author’s version of a work that was accepted for publication in Engineering Failure Analysis. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Engineering Failure Analysis,, 117 (2020) DOI: 10.1016/j.engfailanal.2020.104846

© 2020, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/


  • Materials
  • FEA
  • Structural break
  • Failure analysis
  • Creep
  • Fatigue crack growth
  • Solder
  • Joints
  • Shear stress
  • Thermal Fatigue
  • surface properties of materials

ASJC Scopus subject areas

  • Mechanics of Materials
  • Safety, Risk, Reliability and Quality


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