Microstructural characterization of whiskers and oxidized surfaceson Sn/FeNi42 and Pb-free alloys

H. Sosiati, S. Hata, N. Kuwano, Y. Iwane, Y. Morizono, Y. Ohno

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)


Microstructural characterization was performed by analytical transmission electron microscopy (ATEM) to clarify the formation mechanism of tin whiskers. A tin (Sn)-layer about 10 μm thickness was electrodeposited on a FeNi42 plate. The Sn/FeNi42 plate was heated and cooled repeatedly in a temperature range of 233-403 K for 100 cycles under various atmospheres. Cross-sectional TEM specimens of whiskers on the Sn/FeNi42 plate were prepared using a focused ion beam (FIB) micro-sampling technique. Some artifact-effects of the FIB treatments on microstructures in tin alloys were taken into account. Bent-type whiskers grown on the Sn/FeNi42 are of polycrystalline β-Sn. A tin-oxide layer around 10 nm in thickness is formed on the tin surface. Electron diffraction, high-resolution TEM and electron energy loss spectroscopy (EELS) analyses revealed that the tin-oxide layer is predominantly of crystalline SnO 2. The presence of crystalline SnO was also recognized. It was found that the tin-oxide layer tends to be rather thin around stems of the whiskers. It is interpreted that thermal stress in the tin-layer breaks the thin tin-oxide layer at grain boundaries of tin and the whiskers grow from the broken area. The formation mechanism of the whiskers is discussed.

Original languageEnglish
Title of host publicationCARTS Europe 2006
Number of pages7
Publication statusPublished - 2006
Event20th Annual Passive Components Symposium, CARTS-Europe 2006 - Bad Homburg, Germany
Duration: Sept 25 2006Sept 28 2006

Publication series

NameCARTS Europe 2006


Other20th Annual Passive Components Symposium, CARTS-Europe 2006
CityBad Homburg

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering
  • Industrial and Manufacturing Engineering
  • Safety, Risk, Reliability and Quality
  • Materials Science(all)


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