Safety critical electronics in automotive, avionic or military applications have to work reliably in a range of harsh conditions, including simultaneous mechanical and thermal loads (Gromala, 2021; Qi et al., 2009 [1, 2]). The durability of electronics, more specifically their board level interconnects, under vibration and thermal loads must be investigated and understood for interconnects assembled with lead-free solder alloys. In this study, isothermal vibration fatigue tests have been carried out at −40 °C, 25 °C and 125 °C. A novel test specimen, specifically designed for combined vibration and temperature cycling experiments, was used for this study. The test PCB contains leadless chip resistor (LCR) components, soldered using the SAC105 solder alloy (Sn98.5Ag1.0Cu0.5). Failed specimens at each temperature were subjected to destructive physical analysis (DPA) for root cause analysis (RCA) of the observed failures. Dynamic finite element analysis (FEA) was carried out and combined with the experimental results in order to generate fatigue strain-life (S–N) curves. Two opposing effects of increasing temperature - viz. decrease of fatigue strength for high-cycle fatigue (HCF) and increase of fatigue ductility for low-cycle fatigue (LCF) - are hypothesized to be responsible for this non-monotonic behavior.