Reverse polarity effect from effective charge disparity during electromigration in eutectic Sn-Zn solder interconnect

X. F. Zhang, J. D. Guo, J. K. Shang

Research output: Contribution to journalArticlepeer-review

Abstract

Polarity effect on the interfacial reactions from high-density electric currents was investigated in a solder interconnect with a large disparity in the effective charge between the solder constituents. A reverse polarity effect was found where the intermetallic compound layer at the cathode grew significantly thicker than that at the anode under electric loading. Such an abnormal polarity effect was shown to result from electromigrations of Sn and Zn along opposite directions as dictated by the disparity in their effective charges. As Sn migrated to the anode under electron wind force, the resulting back stress drove Zn atoms to drift to the cathode. A kinetic analysis of the Zn mass transport explained the differential growth of the intermetallic compounds at the two electrodes, in good agreement with the experimental data.

Original languageEnglish (US)
Pages (from-to)3370-3378
Number of pages9
JournalJournal of Materials Research
Volume23
Issue number12
DOIs
StatePublished - Dec 2008

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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