Nanomechanical characterization of Sn-Ag-Cu/Cu joints-Part 2: Nanoindentation creep and its relationship with uniaxial creep as a function of temperature

In the first part of this study we reported the use of nanoindentation to evaluate the mechanical properties of microphases formed within Sn-Ag-Cu-based solder joints as a function of temperature. In this second part, the use of nanoindentation has been extended to study the creep behaviour of these phases in the temperature range 25-175 °C. The data for nanoindentation creep has been compared with that reported for bulk creep behaviour of similar alloys. A methodology has been developed based on finite-element analysis that accounts for (i) the increasing volume of creeping material beneath the indenter as indentation progresses; and (ii) the variation of indentation stress during indentation as the area of indentation increases. Using this approach, nanoindentation creep data is reconciled with bulk creep data.