Intermetallic compound growth mechanism and failure modes of flip chip solder bump with different UBM structure during electromigration

Yong Sheng Zou, Yu Hsiang Hsiao, Kwang-Lung Lin

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

The growth mechanisms of intermetallic compound (IMC) and the failure modes in flip chip solder joint induced by electric current stressing have been investigated for various UBM and substrate metallizations. The UBM investigated was TiCuCuNi/TiCuNi while the substrate metallizations include electroless Ni(P)/electroless Pd/immersion Au (ENEPIG) and organic solderability preservatives (OSP) Cu substrate. The investigation was conducted with 7kA/cm at 160 °C. The main IMCs formed in the TiCuNi-ENEPIG bump were the Ni3Sn4, PdSn4 and AuSn4 phases. The nucleation of (Pd, Ni)Sn4 on Ni3Sn4 layer and the dissolution of Au and Pd into the melting solder form the rod shape AuSn4 and PdSn4 IMCs. The ENEPIG layer acts as barrier layer that inhibits the Cu pad consumption and forms Ni3P layer under electric current stressing. Cu atoms from the Cu pad diffused through the Ni3P layer to form the Cu6Sn5 IMC at the interface instead of the Ni3Sn4 IMC. The main IMCs formed in the bumps with TiCuNi-Cu and the TiCuCuNi-Cu as UBM were the Cu6Sn5 IMC as expected. The failure after the electromigration test occurs either through the expedite consumption of the bottom Cu pad, where no Ni barrier layer, or through the formation of voids and cracks at the IMC/solder interface on the Ni UBM side. The mechanism of void and crack formation was discussed in detail in this study.

Original languageEnglish
Title of host publicationProceedings of the 16th Electronics Packaging Technology Conference, EPTC 2014
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages155-158
Number of pages4
ISBN (Electronic)9781479969944
DOIs
Publication statusPublished - 2014 Jan 30
Event2014 16th IEEE Electronics Packaging Technology Conference, EPTC 2014 - Singapore, Singapore
Duration: 2014 Dec 32014 Dec 5

Publication series

NameProceedings of the 16th Electronics Packaging Technology Conference, EPTC 2014

Other

Other2014 16th IEEE Electronics Packaging Technology Conference, EPTC 2014
CountrySingapore
CitySingapore
Period14-12-0314-12-05

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

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