Shear strength and interfacial microstructure of Sn-Ag-xNi/Cu single shear lap solder joints

Yang Hsien Lee, Hwa-Teng Lee

Research output: Contribution to journalArticlepeer-review

74 Citations (Scopus)


This study investigates composite lead-free solders fabricated by adding between 0.5 and 3 wt% of Ni particles in situ to Sn-3.5 wt%Ag lead-free solder. The single lap shear strength, fracture behavior and microstructural evolution characteristics of the as-reflowed specimens are examined and compared with those of specimens thermally aged at 150 °C for various aging times. In general, it is found that the single lap shear strength of the joints increases with increasing Ni addition in the as-reflowed condition, but decreases with increasing storage time in the aged specimens. For Ni additions of 0.5 and 1 wt%, the specimens fracture in the solder near the intermetallic compound (IMC) layer/solder interface, which suggests that the solder matrix has a lower strength than the IMC layer. The presence of elongated dimple-like structures on the fracture surfaces of these specimens is indicative of a ductile failure mode. For Ni additions of more than 1 wt%, the specimens fracture with brittle characteristics at the solder/IMC interface, which indicates that an increased Ni addition increases the strength of the solder matrix beyond that of the interfacial layer.

Original languageEnglish
Pages (from-to)75-83
Number of pages9
JournalMaterials Science and Engineering A
Issue number1-2
Publication statusPublished - 2007 Jan 25

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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