Printed circuit boards (PCB) are multilayer architectures that are used as substrates for the connection of electronic components. They usually consist of different materials (e.g. polymers, glass fibers, ceramics, metal electrodes) combined in a 3D complex structure. Due to the combination of materials with different properties (e.g. thermal expansion coefficient, elastic constants) significant elastic strains (and consequently mechanical stresses) may occur during the fabrication process and/or in service conditions. Therefore it is essential to know the elastic modulus of the materials involved, in order to assess the mechanical behavior of the PCB within the system. The aim of this diploma thesis was to determine the elastic modulus on thin ceramic and polymer printed circuit boards. Different methods (i.e. 3 Point-, and 4 Point Bending) were first compared on thin and thick (standard) reference samples. The reference materials employed were Silicon Nitride (Si3N4), Y2O3-stabilized Zirconia (Y-TZP) and Aluminium (Al). The testing methodologies were then adapted for thin ceramic and polymer PCB samples; the latter being tested in different orientations. In addition, preliminary tensile tests were attempted on thin ceramic specimens in order to establish testing protocols that should enable the evaluation of the elastic modulus in complex ceramic and polymer PCBs. The outcomes of this work shall serve as input data for the Finite Element simulation of thermo-mechanical loading of a microelectronic system, within the framework of an industrial project.