A study of the thermal properties of materials used in semiconductor electronics has been carried out. The dependence of the thermal resistance of GaAs diodes on the temperature increase of the product body is determined. They are determined taking into account the design solutions of the housing design of the REA, which can protect components from extreme, difficult conditions, but they increase the weight and complexity of the system. Materials such as SiC, GaAs, GaN, diamond that can withstand extreme conditions may have advantages that go far beyond their electronic characteristics. An example of the application of GaAs-based diode modules of p-i-n diodes developed by JSC "VZPP-S" is given - a three-phase bridge rectifier made according to the Larionov scheme for an electric generator with a power of up to 2750 watts. A methodology for conducting reliability tests has been developed. Short-term tests for the reliability of diode modules at extreme housing temperatures were carried out. The results of the calculation of the thermal resistance of the junction-housing are presented. To simplify the calculation of the thermal resistance of the junction-housing of the developed module, we will make the following assumptions: the materials used in the design of the module diodes have isotropic thermal conductivity; heat exchange in the internal parts of the structure is carried out only by thermal conductivity; there are no contact resistances between the layers; the power dissipated by the terminals of the diode crystals is negligible compared with the power discharged through the lower base into the heat sink; the side surfaces of the thermal model are insulated; each layer of the same material is homogeneous and has a thermal conductivity coefficient determined by the average temperature of the layer; the influence of the thermal effect of neighboring crystals of the module is not taken into account. The algorithm of stationary thermal regime (method of equivalents) of Appendix N OST 11 0944-96 is chosen as the basis of calculation.