Creep-fatigue crack growth behavior of Pb-contained and Pb-free solders at room and elevated temperatures

Abstract

Fatigue crack growth tests of lead-contained (Sn-37Pb) and lead-free (Sn-3.0Ag-0.5Cu) solders were conducted under frequencies ranged from 10 to 0.1 Hz and a stress ratio of 0.1 at room temperature and 70 °C. J-integral range (ΔJ) and modified J-integral (C*) were used fordiscussingabout cycle-dependent and time-dependent crack growth behavior forboth the solders. The experimental results showed that crack growth behavior of both the solders waspredominantly time-dependent at lower frequency and higher temperature, while itwas predominantly cycle-dependentat higher frequency and lower temperature.Underthe present test condition of stress ratio of 0.1, when the frequency was higherthan 0.5 Hz at room temperature and 1 Hz at 70 °C for both the solders, crack growth behavior was cycle-dependent. The crack growth resistance of lead-free solder was higher than that of lead-contained solder,which was much significant in time-dependent region. From the fracture surface observations, it was found that as the frequency decreased and/or the temperature increased, the fracture surface appearance changed from transgranular to intergranular manner for both the solders.