Electromigration through a Cu/Sn3.5Ag/Au solder joint results in rotation of the intermetallic compounds (IMCs). The Sn whiskers induced within the unreacted solder were believed to be due to the mechanical stress induced by this IMC rotation. Microstructural investigation and the electron diffraction pattern, revealed by transmission electron microscopy, indicate that the crystalline Sn whiskers grew with inclusion of prominent dislocations. The existence of dislocations within the Sn whiskers suggests that whisker growth experiences turbulence.

The Growth of Sn Whiskers with Dislocation Inclusion Upon Electromigration Through a Cu/Sn3.5Ag/Au Solder Joint. T.C.Chiu, K.L.Lin: Scripta Materialia, 2009, 60[12], 1121-4