The project 'GaAs Power Modules for Communication Systems in the Frequency Range 30-50 GHz' is embedded in the research program 'Mobile Communication' founded by the german Ministry of Education and Research (BMBF). In this work theoretical studies and basic technologies for the integration of 1 Watt power modules with cascaded power cells in flip chip technology were realized. In order to remove the power losses of the unthinned coplanar power cells, additionally to the electrical bump interconnects thermal bumps near the gate fingers on the source pads and high thermal conductive aluminum nitride substrates have been used. The influence of the thermal bump interconnects to the electrical characteristics of the power cells at high frequencies was determined by on wafer measurements. In order to establish a substrate integrated housing technology for frequencies up to 70 GHz coplanar feed through transmission lines have been realized by use of thin film multilayer technology with 25 #mu#m thick polyimide dielectrics. Manufacturing of the GaAs power cells was done in cooperation with Fraunhofer Institute IAF, Freiburg, and electromagnetic simulation of feed throughs, bump connections and parasitic modes in cooperation with Ferdinand braun Institute, Berlin. (orig.)Available from TIB Hannover: F99B1319+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman