Electromigration in pb-free SnAg3.8Cu0.7 solder stripes

Abstract

Electromigration behavior in the eutectic SnAg3.8Cu0.7 solder stripes was investigated in the vicinity of the device operation temperature of 100 degrees C by using the edge displacement technique. Measurements were made for relevant parameters for electromigration of the solder, such as drift velocity, threshold current density, activation energy, as well as the product of diffusivity and effective charge number (DZ(*)). The threshold current densities were estimated to be 4.3x10(4) A/cm(2) at 80 degrees C, 3.2x10(4) A/cm(2) at 100 degrees C, and 1.4x10(4) A/cm(2) at 120 degrees C. These values represent the maximum current densities that the SnAg3.8Cu0.7 solder can carry without electromigration damage at the three stressing temperatures. The electromigration activation energy was determined to be 0.45 eV in the temperature range of 80-120 degrees C. The measured products of diffusivity and the effective charge number, DZ(*), were -1.8x10(-10) cm(2)/s at 80 degrees C, -5.0x10(-10) cm(2)/s at 100 degrees C, and -7.2x10(-10) cm(2)/s at 120 degrees C. (c) 2005 American Institute of Physics.