Abstract : The work focuses on potting materials for electronic components. A methodology to analyse the behaviour of cracks initiated in homogeneous materials or at the interface between different materials is addressed. An experimental procedure is described in order to measure the critical stress intensity factor of a homogeneous material. This procedure is then used to compare the crack behaviour in a bimaterial structure and to determine the validity of the results. Hereafter a method is proposed to determine crack growth under subcritical loading conditions. In the case of a crack at the interface of bimaterials, a methodology has been developed to measure the energy release rate necessary to let the crack propagate. With the help of numerical simulations, the corresponding stress intensity factors are computed as well as the resulting mixed mode angle. The whole work realised experimentally and the developed numerical simulations allow us to propose a methodology to analyse the behaviour of a crack placed in a multi-material structure under thermo-mechanical loads.