"On the very last months, the Gallium Nitride (GaN) technology has made a remarked breakthrough in the world of the microwave electronics with the announcement of commercially available transistors from 5W to 180W at microwave frequencies. Coming from major transistor industrial vendors from Japon but also from US, it let equipment manufacturers and especially the one from space think that time has come now for a rapid insertion into their systems. Outside the reliability and the European source concerns, these GaN power transistors will roughly increase power density by more than an order of magnitude for large devices (from 0.5 W/mm to 5 W/mm for space applications including deratings). The consequence will then directly impact the packaging technology for which the thermal resistance needs to be importantly reduced if the advantages obtained at die level want to remain at its highest at module and equipment level. To address this critical item for space satellite applications is the aim of the proposed project which is in the ESA roadmap [Ref. ESTEC/AC/418-20, ESA-IPC 2006] for GaN component strategy but not funded by ESA. The ESA funding is being mainly dedicated toward GaN transistor process optimization, reliability and industrialization. In this project, AGAPAC, which stands for “Advanced GaN Packaging”, we want to establish a space compatible European supply chain for packaging solution of GaN HEMTs and GaN MMICs by 2010. To realize this project objective, we have defined sub-objectives which directly relate to 7 workpackages targeting: This project will extend beyond state of the art for high thermal dissipation composite (up to 600 W/mK) either based onto diamond or carbon nano-fiber compatible with hybride micropackage manufacturing technologies. The challenge remains in developing a space compatible power micropackage able to withstand up to 100 W of dissipated power when standard same size micropackage are around 25 W."