Growth of a Au-Ni-Sn intermetallic compound on the solder-substrate interface after aging

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Au/Ni metallization has become increasingly common in microelectronic packaging when Cu pads are joined with Pb-Sn solder. The outermost Au layer serves to protect the pad from corrosion and oxidation and the Ni layer provides a diffusion barrier to inhibit detrimental growth of Cu-Sn intermetallics. As a result of reflowing eutectic Pb-Sn on top of Au/Ni metallization, the as-solidified joints have AuSn{sub 4} precipitates distributed throughout the bulk of the solder joint, and Ni{sub 3}Sn{sub 4} intermetallics at the interface. Recent work has shown that the Au-Sn redeposits onto the interface during aging, compromising the strength of the joint. The ... continued below

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Minor, Andrew M. & Morris, J.W., Jr. December 16, 1999.

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Au/Ni metallization has become increasingly common in microelectronic packaging when Cu pads are joined with Pb-Sn solder. The outermost Au layer serves to protect the pad from corrosion and oxidation and the Ni layer provides a diffusion barrier to inhibit detrimental growth of Cu-Sn intermetallics. As a result of reflowing eutectic Pb-Sn on top of Au/Ni metallization, the as-solidified joints have AuSn{sub 4} precipitates distributed throughout the bulk of the solder joint, and Ni{sub 3}Sn{sub 4} intermetallics at the interface. Recent work has shown that the Au-Sn redeposits onto the interface during aging, compromising the strength of the joint. The present work shows that the redeposited intermetallic layer is a ternary compound with stoichiometry Au{sub 0.5}Ni{sub 0.5}Sn{sub 4}. The growth of this intermetallic layer was investigated, and results show that the ternary compound is observed to grow after as little as 3 hours at 150 C and after 3 weeks at 150 C has grown to a thickness of 10 {micro}m. Additionally, methods for inhibiting the growth of the ternary layer were investigated and it was determined that multiple reflows, both with and without additional aging can substantially limit the thickness of the ternary layer.

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OSTI as DE00753105

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  • Other Information: TH: Thesis (M.S.); Submitted to Univ. of California, Berkeley, CA (US)

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  • Report No.: LBNL--44758
  • Grant Number: AC03-76SF00098
  • DOI: 10.2172/753105 | External Link
  • Office of Scientific & Technical Information Report Number: 753105
  • Archival Resource Key: ark:/67531/metadc709319

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • December 16, 1999

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  • Sept. 12, 2015, 6:31 a.m.

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  • April 6, 2016, 1:09 p.m.

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Minor, Andrew M. & Morris, J.W., Jr. Growth of a Au-Ni-Sn intermetallic compound on the solder-substrate interface after aging, thesis or dissertation, December 16, 1999; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc709319/: accessed October 21, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.