Investigation of small Sn-3.5Ag-0.5Cu additions on the microstructure and properties of Sn-8Zn-3Bi solder on Au/Ni/Cu pads

Asit Kumar Gain, Tama Fouzder, Y. C. Chan, Ahmed Sharif, Kam Chuen Yung

Research output: Journal article publicationJournal articleAcademic researchpeer-review

26 Citations (Scopus)


The formation of intermetallic compounds and the shear strength of Sn-Zn-Bi solder alloys with various (0, 1, 3, 5 and 7 wt%) weight percentages of Sn-Ag-Cu were investigated on Au/Ni metallized Cu pads depending on the number of reflow cycles. In Sn-Zn-Bi solder joints, scallop-shaped AuZn3intermetallic compound (IMC) particles were found at the interfaces and in the solder ball regions, fine Bi- and needle-shaped Zn-rich phase were observed in the Sn matrix. After Sn-Ag-Cu additions, an additional Ag-Zn intermetallic compound layer was adhered to the top surface of the AuZn3layer at the interface and fine spherical-shaped AgZn3intermetallic compound particles were detected in the solder ball regions together with Bi- and Zn-rich phase volumes. After the addition of Sn-Ag-Cu, the shear strength of Sn-Zn-Bi solder joints increased due to the formation of the fine AgZn3intermetallic compound particles. The shear strengths of Sn-Zn-Bi and Sn-Zn-Bi/7 wt% Sn-Ag-Cu solder joints after one reflow cycle were about 44.5 and 53.1 MPa, respectively and their shear strengths after eight reflow cycles were about 43.4 and 51.6 MPa, respectively.
Original languageEnglish
Pages (from-to)678-684
Number of pages7
JournalJournal of Alloys and Compounds
Issue number2
Publication statusPublished - 21 Jan 2010


  • Ball grid array solder joints
  • Microstructure
  • Multiple reflows
  • Pb-free
  • Shearing strength

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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