Tin whiskers studied by synchrotron radiation scanning X-ray micro-diffraction

W. J. Choi*, T. Y. Lee, King-Ning Tu, N. Tamura, R. S. Celestre, A. A. MacDowell, Y. Y. Bong, Luu Nguyen

*Corresponding author for this work

Research output: Contribution to journalArticle

158 Scopus citations

Abstract

A large number of Sn whiskers have been found on the Pb-free solder finish on leadframes used in consumer electronic products. Some of the whiskers on eutectic SnCu finishes are long enough to short the neighboring legs of the leadframe. Tin whisker growth is known to be a stress relief phenomenon. We have performed synchrotron radiation X-ray micro-diffraction analysis to measure the local stress level, the orientation of the grains in the finish around a whisker, and the growth direction of whiskers. The compressive stress in the solder finish is quite low, less than 10 MPa; nevertheless, there exists a stress gradient around the root of a whisker. From the orientation map and pole figure, we found that the growth direction of whiskers is [0 0 1] and there exists a preferred orientation of [3 2 1] grains on the solder finish. In one of the whisker analyzed, we found that the normal orientation of the grain just below the whisker is different; it is [2 1 0].

Original languageEnglish
Pages (from-to)6253-6261
Number of pages9
JournalActa Materialia
Volume51
Issue number20
DOIs
StatePublished - 8 Dec 2003

Keywords

  • Grain orientation
  • Pb-free solder
  • Stress gradient
  • Tin whisker
  • X-ray micro-diffractions

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    Choi, W. J., Lee, T. Y., Tu, K-N., Tamura, N., Celestre, R. S., MacDowell, A. A., Bong, Y. Y., & Nguyen, L. (2003). Tin whiskers studied by synchrotron radiation scanning X-ray micro-diffraction. Acta Materialia, 51(20), 6253-6261. https://doi.org/10.1016/S1359-6454(03)00448-8