Micro-mechanics of fatigue damage in Pb-Sn solder due to vibration and thermal cycling

This paper presents a micro-mechanistic approach for modeling fatigue damag e initiation due to cyclic plasticity and cyclic creep in eutectic Pb-Sn so lder. The issue of damage evolution is deferred to a future paper. Fatigue damage model due to cyclic plasticity is modeled with d islocation mechanic s. A conceptual framework is provided to quantify the influence of temperat ure on fatigue damage due to cyclic plasticity. Damage mechanics due to cyc lic creep is modeled with a void nucleation model based on micro-structural stress fields. Micro-structural stress states are estimated under viscopla stic phenomena like grain boundary sliding and its blocking at second phase particles, and diffusional creep relaxation. A conceptual framework is pro vided to quantify the creep-fatigue damage due to thermo-mechanical cycling .