Microstructural study of interfacial reactions between liquid Sn and electroless Fe-Ni alloys

Haifei Zhou, Jingdong Guo, Jian Ku Shang

Research output: Contribution to journalArticlepeer-review


Interfacial reactions between liquid Sn and electroless xFeNiP alloys (where x is the at.% of Fe) were investigated to determine the suitability of electroless Fe-Ni films as a potential under-bump metallization in solder interconnections. It was found that the interfacial reactions depended strongly on the Fe percentage in the electroless Fe-Ni alloys. The FeSn 2 compound layer was observed at the interface of alloys with high atomic percentage of Fe, such as 55 at.% and 75 at.%, while both FeSn 2 and Ni 3Sn 4 layers were found at the interface at low Fe concentration such as 25 at.%. The growth rate of interfacial intermetallic compounds and the amount of intermetallic whiskers grown on the FeNiP coatings decreased with increasing Fe percentage. The presence of FeSn 2 phase in Fe-Ni alloys at different Fe concentrations was believed to result from the lower Gibbs free energy for FeSn2 formation in the Sn/FeNiP system, while the variation in the growth rate of the intermetallic layer with Fe concentration was related to the different growth rates of FeSn 2 and Ni 3Sn 4 compounds.

Original languageEnglish (US)
Pages (from-to)3161-3168
Number of pages8
JournalJournal of Electronic Materials
Issue number11
StatePublished - Nov 2012


  • Electroless Fe-Ni
  • Interfacial reaction
  • Under-bump metallization

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry


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