Direct measurement of hot-spot temperature in flip-chip solder joints under current stressing using infrared microscopy

Hsiang Yao Hsiao, S. W. Liang, Min Feng Ku, Chih Chen*, Da Jeng Yao

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Several simulation studies reported that a hot spot exists in flip-chip solder bumps under accelerated electromigration. Yet, there are no experimental data to verify it. In this paper, the temperature distribution during electromigration in flip-chip SnAg3.5 solder bumps is directly inspected using infrared microscopy. Two clear hot spots are observed in the bump. One is located at the region with peak current density and the other one is at the bump edge under the current-feeding metallization on the chip side. Under a current stress of 1.06× 104 A cm2, the temperature in the two hot spots are 161.7 and 167.8 °C, respectively, which surpass the average bump temperature of 150.5 °C. In addition, the effect of under-bump-metallization (UBM) thickness on the hot spots is also examined. It indicates that the hot-spot temperature in the solder bump increases for the solder joints with a thinner UBM. Electromigration test indicates that these hot spots have significant influence on the initial failure location.

Original languageEnglish
Article number033708
JournalJournal of Applied Physics
Volume104
Issue number3
DOIs
StatePublished - 25 Aug 2008

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