Significantly Improved Mechanical Properties of Bi- Sn Solder Alloys by Ag- Doping

Authors: Mccormack, M.; Chen, H.; Kammlott, G.; Jin, S.

Source: Journal of Electronic Materials, Volume 26, Number 8, August 1997 , pp. 954-958(5)

Publisher: Springer

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Abstract:

The addition of small amounts of Ag (less than ~;0.5 wt. %) is found to significantly improve the ductility of the binary Bi-Sn eutectic solder. The ductility improvement, more than a threefold increase in tensile elongation, is observed even at a relatively high strain rate (0.01 s^-1). As the Bi-Sn binary eutectic alloy tends to fail catastrophically by brittle fracture at high strain rates, the reduced strain-rate sensitivity in the Ag-containing alloy is beneficial for improving solder reliability on sudden impacting as might be encountered during device assembly, shipping, or thermal shock/cycling. The observed increase in alloy ductility by Ag additions is attributed to a substantial refinement of the solidification microstructure.

Keywords: Lead-free; mechanical properties; microstructure; solder

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s11664-997-0281-7

Publication date: 1997-08-01