Electromigration behavior in the eutectic SnAg3.8Cu0.7 solder stripes was investigated in the vicinity of the device operation temperature of 100C 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 4.3 x 104A/cm2 at 80C, 3.2 x 104A/cm2 at 100C, and 1.4 x 104A/cm2 at 120C. These values represent the maximum current densities that the SnAg3.8Cu0.7 solder could carry without electromigration damage at the three stressing temperatures. The electromigration activation energy was determined to be 0.45eV at 80 to 120C. The measured products of diffusivity and the effective charge number were –1.8 x 10–10cm2/s at 80C, –5.0 x 10–10cm2/s at 100C and –7.2 x 10–10cm2/s at 120C.

Electromigration in Pb-Free SnAg3.8Cu0.7 Solder Stripes. Y.C.Hsu, C.K.Chou, P.C.Liu, C.Chen, D.J.Yao, T.Chou, K.N.Tu: Journal of Applied Physics, 2005, 98[3], 033523 (6pp)