Significantly enhanced creep resistance in low-melting-point solders through nanoscale oxide dispersions

Nanosized, nonreacting, and noncoarsening oxide dispersoids have been incorporated into solder alloys to create an improved solder structure with an ultrafine grain size of similar to 2000-5000 Angstrom and significantly enhanced mechanical properties. As much as three orders of magnitude reduction in the steady-state creep rate has been achieved. These solders also exhibit improved (4-5 times higher) tensile strength at low strain rates and improved ductility under high strain rate deformation. It is demonstrated that with a dispersion of TiO2 particles, the Pb-Sn eutectic solder with a low melting point of 183 degrees C can be made more creep resistant than the 80Au-20Sn eutectic solder with a much higher melting point of 278 degrees C. [S0003-6951(98)04342-3].