Journal of Electronic Materials

, Volume 36, Issue 7, pp 753–759 | Cite as

Electromigration in the Flip Chip Solder Joint of Sn-8Zn-3Bi on Copper Pads

  • W.H. Lin
  • Albert T. Wu
  • S.Z. Lin
  • T.H. Chuang
  • K.N. Tu
Article

Electromigration in Sn-8Zn-3Bi flip chip solder bumps on Cu pads has been studied at 120°C with an average current density of 4 × 103 A/cm2 and 4.5 × 104 A/cm2. Due to the polarity effect, the thickness of the intermetallic compound Cu-Zn (γ-phase) formed at the anode is much greater than that at the cathode. The solder joint fails after 117 h of stressing at 4.5 × 104 A/cm2, and void formation at the cathode can clearly be seen after polishing. However, it is the melting at the edge of the bump that causes the solder joint to fail. A simulation of the current density distribution indicates that the current density is not distributed uniformly, and current crowding occurs inside the bump. The results indicate that the increase of current density associated with Joule heating has affected melting and enhanced damage in the solder joint during electromigration.

Keywords

Sn-8Zn-3Bi electromigration flip chip current crowding Joule heating 

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Notes

Acknowledgement

This study is supported by the National Science Council, Taiwan, through Grant No. NSC93-2216-E002-024.

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Copyright information

© TMS 2007

Authors and Affiliations

  • W.H. Lin
    • 1
    • 2
  • Albert T. Wu
    • 3
  • S.Z. Lin
    • 1
  • T.H. Chuang
    • 1
  • K.N. Tu
    • 4
  1. 1.Department of Materials Science and EngineeringNational Taiwan UniversityTaipeiTaiwan
  2. 2.Phoenix Precision Technology CorpHsinChuTaiwan
  3. 3.Institute of Materials Science and EngineeringNational Taipei University of TechnologyTaipeiTaiwan
  4. 4.Department of Materials Science and EngineeringUCLALos AngelesUSA

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