Abstract
Observations by micro Auger electron spectroscopy and X-ray micro analysis have been made on tin films electroplated on substrates of brass or zinc-coated copper, and on whiskers grown on the films. Direct experimental evidence has shown the existence of zinc and oxygen atoms on the surfaces both of the whiskers and the films. Copper atoms have also been detected in the whiskers and the films. A mechanism for the whisker growth is proposed, based on these experimental results. After electroplating, zinc atoms migrate onto the tin surface and bind there with oxygen atoms. At this stage, the nuclei of whiskers are formed, and the whiskers begin to grow with the aid of the internal stresses caused by the recrystallization of tin grains and/or the formation of intermetallic compounds of tin with copper.