The following bachelor thesis discusses a thermal analysis of the support and readout structure of Phase-2 pixel detectors from the Inner Tracker of the CMS detector. The structure is analyzed with a finite element analysis in ANSYS. The model is simulated with different heat loads in the heat-generating parts and the temperature distribution is discussed. Besides, there a critical layer analysis on the different layers of the model is performed. Criteria for the criticality of a material layer are derived and applied to the model. The results show that the current detector design is sufficient to achieve temperatures below .