In this study a temperature-dependent creep characterization of SAC405 solder alloy was performed, with the aim of its implementation into thermomechanical finite element models. The creep behavior of solder interconnects for wafer level packaging was investigated using the constant force nanoindentation method. Nanoindentation was performed in a temperature range from -55 °C to 175 °C, which covers automotive operational conditions as well as standard test and qualification requirements. It was found that a single Garofalo creep model cannot predict creep rates for the whole investigated temperature range with acceptable accuracy due to potential creep mechanism change at temperatures above +125 °C. Hence, the bipartite Garofalo model, which contains eight material constants, was proposed to depict the high-temperature creep behavior of the SAC405 alloy. Material constants are presented in the paper. The proposed model was implemented in a thermomechanical finite element simulation of a temperature cycling test. The temperature cycling reliability test was performed using a specially designed bump-on-pad test structure with different bump population densities. The Weibull analysis was performed, and characteristic life was defined for fully populated and depopulated package layouts: 607 ± 21 and 591 ± 32 cycles, respectively. The finite element model setup is described in detail, and recommendations are made to achieve higher accuracy in the simulation outcome. Implementation of these recommendations in combination with the derived bipartite Garofalo creep model enabled simulations to precisely predict the interconnect failure mode and depict differences in temperature cycling stress with different package layouts. As a result, the maximum creep strain in SAC405 interconnect accumulated per one temperature cycle was 14% higher for the depopulated bump layout configuration. This result confirms an inverse correlation between calculated accumulated creep strain and characteristic life. In addition, an FE comparative analysis of Anand, bipartite Garofalo, and conventional Garofalo models is discussed.