Thermomigration of Cu-Sn and Ni-Sn intermetallic compounds during electromigration in Pb-free SnAg solder joints

Hsiao Yun Chen, Chih Chen*

*Corresponding author for this work

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

Thermomigration in Pb-free SnAg solder alloys is investigated during accelerated electromigration tests under 9.7 × 103 A/cm 2 at 150 °C. It is found that Cu-Sn intermetallic compounds (IMCs) migrate toward the cold end on the substrate side and, as a result, voids accumulate in the chip side for the bump with current flowing from the substrate end to the chip end. Theoretical calculations indicate that the thermomigration force is greater than the electromigration force at a thermal gradient above 400 °C/cm for this stressing condition. Copper atoms may migrate against current flow and become the dominant diffusion species. On the other hand, Ni-Sn IMCs did not migrate even under a huge thermal gradient of 1400 °C/cm. These findings provide more understanding on the thermomigration of metallization materials in flip-chip solder joints.

Original languageEnglish
Pages (from-to)983-991
Number of pages9
JournalJournal of Materials Research
Volume26
Issue number8
DOIs
StatePublished - 28 Apr 2011

Keywords

  • Diffusion
  • Packaging

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