The application of electronic products is established in many fields of everyday life, for example in automotive industry, medical or communication technology. This leads to the necessity of investigation of safety and reliability of such components. During lifetime testing of the electronic component different loads and mechanisms can lead to degradation and failure. For die attach materials these failures can be cohesive or adhesive in their nature. In order to find an estimate for the quantitative amount of die attach degradation the modification or change of thermal behaviour can give an indication ([3], [4], [5]). In [3] the temperature versus time measurement demonstrates the effect of die-attach degradation on thermal impedance through the life time of a MOSFET package.