Journal of Material Research, Vol. 23, No. 9, pp. 2333-2339, Sep 2008

Electromigration and thermomigration behaviour of flip chip solder joints in high current density packages

D. Yang
Y.C. Chan
B.Y. Wu
Department of Electronic Engineering
City University of Hong Kong
Kowloon Tong, Hong Kong

M. Pecht
Center for Advanced Life Cycle Engineering (CALCE)
Department of Mechanical Engineering
University of Maryland, College Park, MD 20742


The electromigration and thermomigration behaviour of eutectic tin-lead flip chip solder joints, subjected to currents ranging from 1.6 to 2.0 A, at ambient temperatures above 100 °C, was experimentally and numerically studied. The temperature at the chip side was monitored using both a temperature coefficient of resistance method and a thermal infrared technique. The electron wind force and thermal gradient played the dominant role in accelerated atomic migration. The atomic flux of lead due to electromigration and thermomigration was estimated for comparison. At the current crowding region, electromigration induced a more serious void accumulation as compared with thermomigration. Also, because of different thermal dissipations, a morphological variation was detected at different cross-sectional planes of the solder joint during thermomigration.

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