Automotive electronic devices are exposed to substantially harsher thermomechanical loads compared to commercial consumer electronic products. Inside an electronic device, there is a large number of solder joints, supporting the electrical as well as the mechanical interconnections. In terms of mechanical properties, solder joints are a weak point of the whole device assembly and can ultimately determine its reliability. In the past two decades, significant efforts have been made to set up methodologies for lifetime prediction of solder joints in automotive applications. Finite Element Analysis (FEA) is being increasingly employed with the aim to support product design and qualification process. However, constitutive FE models for solder alloys capable of describing their mechanical behavior at the relevant conditions of automotive applications are still not widely established. The currently employed state of the art material models applied in industry and research are based on uni-axial stationary creep. Thus, they naturally fail to describe properly the complex cyclic time-, strain rate, and temperature dependent behavior under the full temperature range of accelerated qualification lab tests and operation conditions. Furthermore, intrinsic degradation processes due to cyclic thermo-mechanical loading are not still completely investigated and are not taken into account within FE-calculations. Current FE-reliability prediction methodologies for solder joints are not possible without the usage of lifetime models (e.g. Coffin-Manson) and their calibration on a substantial set of experimental data. Due to the lack of models mapping intrinsic material degradation, the current prediction methods remain strongly constraint to a single solder type and loading conditions used within the lifetime experiments. More advanced techniques, originally proposed for steel alloys, employ viscoplastic constitutive models and damage mechanics and provide a powerful framework for predictive FE-based lifetime assessment. The goal of the present work is to build on these concepts and extend them for usage in solder joint simulations. An important part of the methodology development is the advanced experimental characterization necessary to obtain the material behavior, which extends the currently available research activities on solder alloys. The experimental investigations are focused on the intrinsic mechanical and aging properties of a Sn-based solder alloy and used for the formulation of a suitable FE-material model within the frame of damage mechanics. Within the thesis, a material testing procedure has been developed in order to perform mechanical characterization on standardized specimens. The test program includes strain rate controlled cycling, stress relaxation phases, uniaxial and multiaxial Low Cycle Fatigue (LCF) as well as creep tests in the temperature range: -40°C up to 125°C. As a first step, the mechanical and microstructure properties of the material in the initial state prior degradation are investigated. A viscoplastic material model of two viscous functions originally proposed by Chaboche et al. has been numerically implemented for 3D simulations. The model maps the observed stress dependence on temperature, time and strain-rate of the alloy in both low and high strain rate regimes. A step by step procedure for calibration of the model parameters in the temperature range -40/125°C is detailed and discussed. As a second step, aging mechanisms are investigated by means of creep and fatigue tests. A lifetime concept based on creep-fatigue partitioning is worked out and applied for the lifetime assessment of a real Surface Mounted Device (SMD) chip resistor under temperature cycling. The method’s predictions are correlated to reported experimental lifetime data within the project LiVe [1]. The proposed creep-fatigue partitioning approach provides means for fast estimation of solder joint reliability and might be used as a support of the design process of electronic devices. Finally, a full Continuum Damage Mechanics (CDM) model, which involves intrinsic damage propagation inside the material, has been developed and implemented for 3D simulations. Based on the observed aging properties, the damage model formulation takes into account local material softening due to creep-fatigue interaction. The CDM-simulation reveals the evolution of degradation in the solder joint component throughout its complete loading history. The main findings are discussed and put into perspective for future works dedicated to the implementation of the CDM approach for reliability prognosis and engineering lifetime concepts.