Accelerated Testing of Sn Whisker Growth

To control the growth of the diameter of a whisker at the anode, we can sputter a thin coating of quartz over the entire Sn strip with an etched hole of a given diameter at the anode. With an applied current density, a whisker can be pushed out from the hole at the anode. We can measure the growth rate and the volume of the whisker as a function of current density, tem- 

Erom the point of view of growth mechanism of spontaneous Sn whiskers, it requires both stress generation and stress relaxation to occur simultaneously. The three necessary and sufficient conditions are fast atomic diffusion at room temperature in Sn, compressive stress, which comes from the room temperature reaction between Cu and Sn from the CugSnj compounds in the grain boundaries of the Sn, and the native oxide, which is protective. 

The authors would like to thank the SRC Contract No. NJ-853, supported by the Semiconductor Research Corporation and National Semiconductor Corporation. 

Herring and J.K. Galt, Elastic and Plastic Properties of Very Small Metal Specimens, Phys. Rev. Vol. 85, p 1060, 1952 

A Mechanism of Whisker Growth, Acta Metall. Vol. 3, p 367 1955 

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