Electromigration induced high fraction of compound formation in SnAgCu flip chip solder joints with copper column

Luhua Xu*, Jung Kyu Han, Jarrett Jun Liang, King-Ning Tu, Yi Shao Lai

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

To overcome the effect of current crowding on electromigration-induced pancake-type void formation in flip chip solder joints, two types of Cu column in 90 μm flip chip SnAgCu solder joints have been studied. They were (1) the solder contacts the Cu column at bottom and side walls and (2) the solder wets only the bottom surface of the copper column. With a current density of 1.6× 104 A cm2 at 135 °C, no failure was detected after 1290 h. However, the resistance increased by about 10% due to the formation of a large fraction of intermetallic compounds. We found that electromigration has accelerated the consumption rate of copper column and converted almost the entire solder joint into intermetallic compound. Mechanically, drop impact test indicates a brittle fracture failure in the intermetallic. The electromigration critical product for the intermetallic is discussed.

Original languageEnglish
Article number262104
JournalApplied Physics Letters
Volume92
Issue number26
DOIs
StatePublished - 11 Jul 2008

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