Effect of small Sn-3.5Ag-0.5Cu additions on the structure and properties of Sn-9Zn solder in ball grid array packages

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

Research output: Journal article publicationJournal articleAcademic researchpeer-review

28 Citations (Scopus)


Sn-9Zn with various additions of Sn-3.5Ag-0.5Cu powder was prepared by mechanically dispersing different weight percentages (1, 3, 5 and 7) of Sn-Ag-Cu powder into Sn-9Zn solder paste. In the Sn-Zn solder, scallop-shaped AuZn3intermetallic compound was found at the interfaces. On the other hand, in the Sn-3.5Ag-0.5Cu content solders, an additional ε-AgZn3intermetallic compound layer was found to be well adhered on the top surface of the AuZn3layer and the ε-AgZn3layer thickness increased with the number of reflow cycles. In addition, fine spherical-shaped ε-AgZn3intermetallic compound particles as well as an acicular-shaped Zn-rich phase was clearly observed in the β-Sn matrix. On increasing the Sn-Ag-Cu content, the shear load was increased from 1.80 to 2.03 kg after one reflow cycle. In the Sn-3.5Ag-0.5Cu content solders, the fracture surfaces exhibited typical ductile behavior with very rough dimpled surfaces while the fracture surface in the Sn-Zn solder gave fractures with a brittle appearance. In the fracture surface of the Sn-3.5Ag-0.5Cu content solders, some dimples were clearly observed associated with the formation of spherical-shaped ε-AgZn3intermetallic compound particles.
Original languageEnglish
Pages (from-to)2347-2353
Number of pages7
JournalMicroelectronic Engineering
Issue number11
Publication statusPublished - 1 Nov 2009


  • Ball grid array solder joints
  • Microstructure
  • Shearing force

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics


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