Reaction of Au/Pd/Cu and Au/Pd/Au/Cu multilayers with Sn-Ag-Cu alloy

The requirements of low resistivity and small magnetic permeability in the high-frequency signal delivery applications have driven the development of Ni-free surface finishes, such as Au/Pd (EPIG) or Au/Pd/Au (IGEPIG), over the Cu conducting lines. The compatibility of these newly developed surface...

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Veröffentlicht in:Surface & coatings technology 2019-01, Vol.358, p.753-761
Hauptverfasser: Huang, Y.H., Hsieh, W.Z., Lee, P.T., Wu, Y.S., Kuo, T.T., Ho, C.E.
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Sprache:eng
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Zusammenfassung:The requirements of low resistivity and small magnetic permeability in the high-frequency signal delivery applications have driven the development of Ni-free surface finishes, such as Au/Pd (EPIG) or Au/Pd/Au (IGEPIG), over the Cu conducting lines. The compatibility of these newly developed surface finish techniques with microelectronic packages and their long-term, high temperature reliability still require investigations in the current state. We conducted a solderability evaluation on the Au/Pd/Cu and Au/Pd/Au/Cu multilayers and found no noticeable differences of the intermetallic compound species (i.e., (Cu,Pd)6Sn5 and Cu3Sn) in the joint interfaces between the two examined cases. However, numerous bump voids might be formed in the vicinity of the solder/Cu interface of the EPIG case, degrading the shear resistance of solder joints. The formation mechanism of the bump voids and the evolution kinetics were proposed in this study. •A comparative study between Au/Pd/Cu (EPIG) and Au/Pd/Au/Cu (IGEPIG).•Au nanolayer (10 nm) inhibited the bump void formation.•Bump voids merged as larger ones upon soldering.•Bump voids degraded the LSBS resistance of solder joints.•IGEPIG surface finish possesses better solderability than EPIG.
ISSN:0257-8972
1879-3347
DOI:10.1016/j.surfcoat.2018.11.085