Isothermal creep of eutectic SnBi and SnAg solder and solder joints

The isothermal tensile steady state creep rates of cast SnBi and SnAg eutectics are reported at temperatures between 20/spl deg/C and 160/spl deg/C, The SnBi eutectic has three regions of stress dependence with an extended power law region with stress exponent, n=3, at rates relevant to thermal fatigue. The SnAg eutectic has a simple power law stress dependence with a stress exponent between 6.7 (high temperatures) and 8.4 (low temperatures). These results are compared to room temperature creep rates of lap shear solder joints. The SnBi data correlate well. SnAg lap shear joints were significantly stronger than bulk samples. The difference is due to the amount of copper dissolved in the solder during reflow.<
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