IEEE Transactions on Electronics Packaging Manufacturing, Vol. 33, No. 3, July 2010

Electrical Shorting Propensity of Tin Whiskers

Sungwon Han, Student Member, IEEE and Michael Osterman, Member, IEEE
CALCE Electronic Products and Systems Consortium
University of Maryland
College Park, MD 20742 USA

Michael G. Pecht, Fellow, IEEE
City University of Hong Kong,
Hong Kong, China
CALCE Electronic Products and Systems Consortium,
University of Maryland,
College Park, MD 20742 USA.


When a tin whisker bridges two differently biased conductors, an electrical short is not guaranteed. In many instances, the voltage must exceed a threshold level in order to produce current flow due to weak physical contact and the presence of a non-conductive film such as an oxide layer. This paper presents a study that examines the breakdown voltage of tin whiskers and its relation to contact force. Whisker contact force studies were conducted using gold- and tin-coated tungsten probes, and the breakdown voltage was measured using a semiconductor parameter analyzer. It was verified that contact force is a critical factor in determining the type of current-voltage transition and level of breakdown voltage. Lower contact force between the probe and the whiskers caused the multiple transitions in current-voltage characteristics. The tin oxide layers on whiskers were analyzed using field emission transmission electron microscopy (FE-TEM).

Index Terms: Breakdown voltage, contact force, electrical short, tin oxide, tin whisker.

Complete article available to CALCE consortium members

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