Optimum thickness of Sn film for whisker growth

Jing Cheng, Fuqian Yang, Paul T. Vianco, Bei Zhang, James C.M. Li

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

By depositing different thicknesses of Sn films over a silicon wafer precoated with Cr and Ni adhesion layers and then by bending the tinned wafer using a dead load applied at the center to introduce the same compressive stresses in the Sn films, the growth rate of whiskers appeared to have a maximum for a certain thickness. This is explained by assuming the Sn atoms to flow along the vertical grain boundaries (perpendicular to the interface) into the interface between Sn and Ni and then along the interface to the root of the whisker through some more vertical grain boundaries. The resistance along the vertical grain boundaries appeared to control the rate of whisker growth for thick films.

Original languageEnglish
Pages (from-to)2069-2075
Number of pages7
JournalJournal of Electronic Materials
Volume40
Issue number10
DOIs
StatePublished - Oct 2011

Keywords

  • Sn films
  • Tin whiskers
  • interface flow
  • squeezing flow
  • thickness effect

ASJC Scopus subject areas

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

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