Creep characterization of lead-free solder alloys over an extended temperature range used for fatigue modeling

Temperature-dependent creep characterization of SAC405 and SACQ solder alloys was performed using the constant force nanoindentation method. Creep rate behavior was investigated in a temperature range from −55°C to 175°C to develop the Garofalo creep model for both materials. The bipartite Garofalo model was proposed to describe a creep behavior for the whole temperature range, as the single model was not suitable to describe experimentally measured creep rates accurately.The derived Garofalo creep models were implemented in the thermomechanical finite element (FE) model to simulate accumulated creep, during two different temperature cycling conditions. The FE results of the derived bipartite Garofalo model were compared with the classic single model approach. In addition, using FE analysis, Garofalo material models were compared to Anand models available from literature for corresponding alloys.