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Interactions between liquid Sn-Bi based solders and contact metals for high temperature applications
conference contribution
posted on 2009-02-11, 14:54 authored by Jianfeng Li, Samjid H. Mannan, Mike P. Clode, H.M. Lobato, Changqing Liu, David Whalley, F.T. Lawrence, G. Jackson, H. SteenLiquid solder interconnects are promising as an alternative
approach to conventional high melting point solder
interconnects for applications where the operating
temperature is likely to exceed 125°C. In order to ensure that
a liquid solder interconnect remains in contact with the
terminations on the component and the substrate, and that
electrical contact between them remains unbroken, there must
be some growth of an intermetallic compound (IMC) at the
interfaces between the solder and the contact metallizations.
However, given that IMC growth is generally much faster
when the solder is liquid, the growing IMC must act as a
strong diffusion barrier to suppress further IMC growth. This
paper presents preliminary studies of liquid-phase Sn-Bi
based solders that result in stable interfaces between the
solders and three common contact metallizations, consisting
of electroless Ni(P)/Au, of Cu and of Ti-W. Small quantities
(1 or 2 %) of an additional element, including Cr, Si, Zn, Ag,
Au, Al and Cu, have been alloyed with the eutectic Sn-Bi
composition to find an effective inhibitor additive that can
achieve a strong IMC diffusion barrier. IMCs and their
growth rates, as well as the consumption rates of the three
contact metallizations in contact with the molten solders, were
investigated. Storage temperatures of 200°C and 240°C were
used, with storage times ranging between two hours and one
month. Results to date show that suitable additives can
significantly reduce IMC growth rates for both the Ni(P)-Au
and Cu contact metallizations, while no appreciable IMC
growth is observed for Ti-W in contact with both the original
and the various alloyed Sn-Bi based solders. Based on the
current results, criteria to further assist the design of feasible
molten liquid solder – contact metallization systems have
been deduced.
History
School
- Mechanical, Electrical and Manufacturing Engineering
Citation
LI, J.F....et al., 2005. Interactions between liquid Sn-Bi based solders and contact metals for high temperature applications. IN: Proceedings of the 55th Electronic Components and Technology Conference, 31 May-3 June, Lake Buena Vista, Fl., Vol. 1, pp. 441-451.Publisher
© IEEEVersion
- VoR (Version of Record)
Publication date
2005Notes
This is a conference paper [© IEEE]. It is also available at: http://ieeexplore.ieee.org/ Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEEISSN
0569-5503Language
- en