標題: Influence of Cu column under-bump-metallizations on current crowding and Joule heating effects of electromigration in flip-chip solder joints
作者: Liang, Y. C.
Tsao, W. A.
Chen, Chih
Yao, Da-Jeng
Huang, Annie T.
Lai, Yi-Shao
材料科學與工程學系
Department of Materials Science and Engineering
公開日期: 15-二月-2012
摘要: The electromigration behavior of SnAg solder bumps with and without Cu column under-bump-metallizations (UBMs) has been investigated under a current density of 2.16 x 10(4) A/cm(2) at 150 degrees C. Different failure modes were observed for the two types of samples. In those without Cu column UBMs, when SnAg solder bumps that had implemented 2 mu m Ni UBMs were current stressed at 2.16 x 10(4) A/cm(2), open failure occurred in the bump that had an electron flow direction from the chip side to the substrate side. However, in those with Cu column UBMs, cracks formed along the interface of Cu6Sn5 intermetallic compounds and the solder on the substrate side in the Sn-3.0Ag-0.5Cu solder bump that had an electron flow direction from the substrate side to the chip side. A three-dimensional simulation of the current density distribution was performed in order to obtain a better understanding of the current crowding behavior in solder bumps. The current crowding effect was found to account for the void formation on both the chip and the substrate side for the two kinds of solder bumps. One more important finding, as confirmed by infrared microscopy, is that the alleviation of current crowding by Cu column UBMs also helped decrease the Joule heating effect in solder bumps during current stressing. Therefore, the measured failure time for the solder joints with Cu column UBMs appears to be much longer than that of the ones with the 2 mu m Ni UBMs. (C) 2012 American Institute of Physics. [doi:10.1063/1.3682484]
URI: http://dx.doi.org/10.1063/1.3682484
http://hdl.handle.net/11536/15630
ISSN: 0021-8979
DOI: 10.1063/1.3682484
期刊: JOURNAL OF APPLIED PHYSICS
Volume: 111
Issue: 4
結束頁: 
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