Damage, fatigue and failure of advanced electronic packages of MEMS and related systems are often caused by their growing use under harsh environmental conditions as well as extreme temperatures. Consequently, their thermo mechanical reliability becomes more and more one of the most important preconditions for adopting it in industrial applications. Various kinds of inhomogeneity, residual stresses from several steps of the manufacturing process along with the fact that microelectronic packages are basically compounds of materials with quite different Young's moduli and thermal expansion coefficients contribute to interface delamination, chip cracking and fatigue of solder interconnects. Subsequently, numerical investigations by means of nonlinear FEA, fracture mechanics concepts are frequently used for design optimizations using sensitivity analyses. Parameters used for such sensitivity analyses are typically materials parameters, geometrical and physical boundary conditions but, especially, the influence of geometrical design parameters on the thermo-mechanical reliability is more and more asked for. This paper intends to demonstrate and discuss advantages and needs of using fully parameterized finite element modeling techniques for design optimizations on the basis of damage evaluation and fracture mechanics approaches. For improving that method, the evaluation of mixed mode interface delamination phenomena and thermal fatigue of solder joints were combined with experimental investigations using a gray scale correlation method. Some results of examinations with respect to different meshing techniques and rules should help to clarify their influence on FEA results. So, the combination of numerical and experimental investigations should give a reliable basis for understanding and evaluating failure mechanisms for arising the thermo-mechanical reliability of microcomponents.