JOM

, Volume 62, Issue 7, pp 22–29

Electromigration performance of Pb-free solder joints in terms of solder composition and joining path

  • Sun-Kyoung Seo
  • Sung K. Kang
  • Moon Gi Cho
  • Hyuck Mo Lee
Lead-Free Solders / Research Summary

Abstract

The electromigration (EM) performance of Pb-free solder joints is investigated in terms of solder composition (Sn-0.5Cu vs. Sn-1.8Ag) and joining path to Cu vs. Ni(P) under bump metallization (UBM). In the double-sided joints of Ni(P)/solder/Cu, the micro-structure of solder joints and the interfacial intermetallic compound (IMC) layers are significantly affected by solder composition and joining path. The as-reflowed microstructure of Sn-0.5Cu joints consists of small columnar grains with thin IMC layers at both UBM interfaces, independent of the joining path, while Sn-1.8Ag joints have a few large grains of low-angle grain boundaries with thick IMC layers when joined first to Ni(P) UBM, but a few 60° twins with thin IMC layers when joined first to Cu UBM. The EM stressing under high current densities at 150°C reveals that Sn-1.8Ag joints have a superior lifetime compared to Sn-0.5Cu joints. In addition, the EM lifetime of Sn-1.8Ag joints reflowed first on Ni(P) UBM is the longest among four groups of the solder joints examined.

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Copyright information

© TMS 2010

Authors and Affiliations

  • Sun-Kyoung Seo
    • 1
  • Sung K. Kang
    • 2
  • Moon Gi Cho
    • 1
  • Hyuck Mo Lee
    • 3
  1. 1.Samsung ElectronicsYonginRepublic of Korea
  2. 2.IBM T.J. Watson Research CenterYorktown HeightsUSA
  3. 3.Department of Materials Science and EngineeringKAISTDaejeonRepublic of Korea

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