Barrier properties of thin Au/Ni–P under bump metallization for Sn–3.5Ag solder

Electroless Ni–P with a thin layer of immersion gold has been considered as a promising under bump metallization (UBM) for low-cost flip–chip technology. However, the presence of P in electroless Ni–P causes complicated interfacial reactions, which affect the reliability of solder joint. In this wor...

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Main Authors: Kumar, Aditya, He, Min, Chen, Zhong
Other Authors: School of Materials Science & Engineering
Format: Article
Language:English
Published: 2013
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Online Access:https://hdl.handle.net/10356/95228
http://hdl.handle.net/10220/9385
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Institution: Nanyang Technological University
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spelling sg-ntu-dr.10356-952282023-07-14T15:45:11Z Barrier properties of thin Au/Ni–P under bump metallization for Sn–3.5Ag solder Kumar, Aditya He, Min Chen, Zhong School of Materials Science & Engineering DRNTU::Engineering::Materials::Microelectronics and semiconductor materials Electroless Ni–P with a thin layer of immersion gold has been considered as a promising under bump metallization (UBM) for low-cost flip–chip technology. However, the presence of P in electroless Ni–P causes complicated interfacial reactions, which affect the reliability of solder joint. In this work, barrier properties of thin Au/Ni–P UBM between Cu substrate and Sn–3.5Ag solder were investigated during annealing at 160, 180, and 200 °C in terms of IMC formation. Multilayer Sn–3.5Ag/Au/Ni–P/Cu sample was prepared by electroless chemical plating and solder reflow for the investigation. Annealing results showed that electroless Ni–P acts as a good barrier for Sn diffusion at 160 and 180 °C. However, it fails to protect the Cu substrate from reacting with Sn at 200 °C. The reason is that the electroless Ni–P layer starts converting into a ternary Ni–Sn–P layer at 200 °C. Complete conversion of the Ni–P layer into Ni–Sn–P, results in the formation of two Cu–Sn intermetallics, Cu6Sn5 and Cu3Sn, at the Ni–Sn–P/Cu interface and the formation of (NixCu1−x)6Sn5 intermetallic at the Ni3Sn4/Ni–Sn–P interface. Accepted version 2013-03-12T04:07:38Z 2019-12-06T19:10:48Z 2013-03-12T04:07:38Z 2019-12-06T19:10:48Z 2004 2004 Journal Article Kumar, A., He, M., & Chen, Z. (2005). Barrier properties of thin Au/Ni–P under bump metallization for Sn–3.5Ag solder. Surface and Coatings Technology, 198(1-3), 283-286. 0257-8972 https://hdl.handle.net/10356/95228 http://hdl.handle.net/10220/9385 10.1016/j.surfcoat.2004.10.085 en Surface and coatings technology © 2004 Elsevier B.V. This is the author created version of a work that has been peer reviewed and accepted for publication by Surface and Coatings Technology, Elsevier B.V. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1016/j.surfcoat.2004.10.085 ]. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic DRNTU::Engineering::Materials::Microelectronics and semiconductor materials
spellingShingle DRNTU::Engineering::Materials::Microelectronics and semiconductor materials
Kumar, Aditya
He, Min
Chen, Zhong
Barrier properties of thin Au/Ni–P under bump metallization for Sn–3.5Ag solder
description Electroless Ni–P with a thin layer of immersion gold has been considered as a promising under bump metallization (UBM) for low-cost flip–chip technology. However, the presence of P in electroless Ni–P causes complicated interfacial reactions, which affect the reliability of solder joint. In this work, barrier properties of thin Au/Ni–P UBM between Cu substrate and Sn–3.5Ag solder were investigated during annealing at 160, 180, and 200 °C in terms of IMC formation. Multilayer Sn–3.5Ag/Au/Ni–P/Cu sample was prepared by electroless chemical plating and solder reflow for the investigation. Annealing results showed that electroless Ni–P acts as a good barrier for Sn diffusion at 160 and 180 °C. However, it fails to protect the Cu substrate from reacting with Sn at 200 °C. The reason is that the electroless Ni–P layer starts converting into a ternary Ni–Sn–P layer at 200 °C. Complete conversion of the Ni–P layer into Ni–Sn–P, results in the formation of two Cu–Sn intermetallics, Cu6Sn5 and Cu3Sn, at the Ni–Sn–P/Cu interface and the formation of (NixCu1−x)6Sn5 intermetallic at the Ni3Sn4/Ni–Sn–P interface.
author2 School of Materials Science & Engineering
author_facet School of Materials Science & Engineering
Kumar, Aditya
He, Min
Chen, Zhong
format Article
author Kumar, Aditya
He, Min
Chen, Zhong
author_sort Kumar, Aditya
title Barrier properties of thin Au/Ni–P under bump metallization for Sn–3.5Ag solder
title_short Barrier properties of thin Au/Ni–P under bump metallization for Sn–3.5Ag solder
title_full Barrier properties of thin Au/Ni–P under bump metallization for Sn–3.5Ag solder
title_fullStr Barrier properties of thin Au/Ni–P under bump metallization for Sn–3.5Ag solder
title_full_unstemmed Barrier properties of thin Au/Ni–P under bump metallization for Sn–3.5Ag solder
title_sort barrier properties of thin au/ni–p under bump metallization for sn–3.5ag solder
publishDate 2013
url https://hdl.handle.net/10356/95228
http://hdl.handle.net/10220/9385
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