Impact of Gold Thickness on Interfacial Evolution and Subsequent Embrittlement of Tin–Lead Solder Joints

Journal Article · 20 September 2022 · Journal of Electronic Materials

DOI: https://doi.org/10.1007/s11664-022-09891-2 · OSTI ID:1889394

Wheeling, Rebecca  ^[1]; Vianco, Paul ^[1]; Williams, Shelley ^[1]; Jauregui, Luis ^[1]; Gallis, Dorina Sava ^[1]

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1. Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

Although gold remains a preferred surface finish for components used in high-reliability electronics, rapid developments in this area have left a gap in the fundamental understanding of solder joint gold (Au) embrittlement. Furthermore, as electronic designs scale down in size, the effect of Au content is not well understood on increasingly smaller solder interconnections. As a result, previous findings may have limited applicability. The current study focused on addressing these gaps by investigating the interfacial microstructure that evolves in 63Sn-37Pb solder joints as a function of Au layer thickness. Those findings were correlated to the mechanical performance of the solder joints. Increasing the initial Au concentration decreased the mechanical strength of a joint, but only to a limited degree. Kirkendall voids were the primary contributor to low-strength joints, while brittle fracture within the intermetallic compounds (IMC) layers is less of a factor. The Au embrittlement mechanism appears to be self-limiting, but only once mechanical integrity is degraded. Sufficient void evolution prevents continued diffusion from the remaining Au.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: NA0003525
• OSTI ID: 1889394
• Report Number(s): SAND2022-12213J; 709725
• Journal Information: Journal of Electronic Materials, Journal Name: Journal of Electronic Materials Journal Issue: 12 Vol. 51; ISSN 0361-5235
• Publisher: SpringerCopyright Statement
• Country of Publication: United States
• Language: English