Electronic packages are multimaterial structures. Their reliability is a major concern for the electronic industry and therefore widely studied. Apart from the electrical performance, the mechanical stability also needs attention. A dreaded failure cause is delamination. Therefore it is interesting to have a modeling tool, which can provide information on possible delamination risks. In this paper, a short overview of existing appropriate analyzing techniques is presented, focusing on the fracture-mechanics approach. The implementation of the method using energy release rate components is discussed. However, as in all modeling applications, the need for “critical material data” is also at hand. Therefore, the shear test is demonstrated to serve as a characterization tool. The Si-BCB interface is applied as test-case. In order to obtain the critical material data for this interface, a set of experiments is designed and performed. Due to the brittle failure observed in the experiments, only information about the onset of the delamination is obtained, leading to a crack extension locus. By comparing the experimental results and the numerical finite element results, an estimation on this crack extension locus (in the plane) can be made. This information can be used in later calculations on the reliability of components including Si-BCB interfaces.