NASA Goddard Space Flight Center
Experiment 4
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Experiment #4:  Future Work is Planned

Demonstration of the Bending of a Tin Whisker Caused by Electrostatic Attraction

Experimental Results

Summary of Experimental Findings
"The Continuing Dangers of Tin Whiskers and Efforts to Control Them with Conformal Coat".  This interim report is published in the NASA EEE Links Newsletter July 2001

Purpose:

To demonstrate that the probability of tin whisker induced short is increased by electrostatic attraction which will cause the whisker to bend.

Test Set-Up:

An electromagnetic relay plated with pure tin was found to have a very long tin whisker growing from the surface of its mounting tab.  The mounting tab was electrically grounded and a test probe tip was brought into close proximity of the tin whisker.  The probe tip was placed at an electrical potential of 50 V relative to the tin whisker in order to demonstrate the bending of the whisker due to electrostatic attraction. 

Results:
The photograph shown below illustrates how the tin whisker is capable of bending under the forces of electrostatic attraction.  This experiment was repeated hundreds of times with this same tin whisker without causing the whisker to break loose from its base.  This experiment demonstrates that the likelihood of tin whisker induced shorts is increased by electrostatic attraction.

BEFORE

Tin Whisker Growing from Electromagnetic Relay Header.
Tin Whisker is Grounded and Test Probe (Upper Right) is Not Charged

AFTER

Tin Whisker is Capable of BENDING Due to Electrostatic Attraction
Test Probe is Charged to 50 Volts Relative to the Tin Whisker.

 
Responsible NASA Officials:

   Michael Sampson/NASA GSFC Code 306
   Dr. Henning Leidecker/NASA GSFC Code 562		 Additional Researchers: 

   Jong Kadesch/Orbital Sciences Corp.
   Jay Brusse/QSS Group, Inc.

Last Updated:

April 20, 2005

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