Abstract: A process of construction of a device for hermetic sealing in a case comprising a sealed ceramic crossover formed by a metal conductor, without having recourse to the technology of cast alumina, which is delicate and costly, and without using sealing glass which is undesirable for very high frequencies. The process comprises the manufacture of molded parts by pressing green alumina to which binders have been added, so as to obtain a case bottom and a frame, which is metalized only after previous firing at 1000.degree. C., using the molybdenum-manganese deposit by silk-screen printing, then which is sintered at the normal temperature of alumina at 1500.degree. C.

Abstract: A low thermal resistance insulating support permitting thermal stresses in the base of a high power component incorporating a beryllium oxide element without fractures or flaws occurring. The support includes a dissipating support made from copper, whose two large faces are slotted to at least partly house a beryllium oxide disk which receives a component and its connections to the outside. Such also completely houses a molybdenum disk with an expansion coefficient close to that of the beryllium oxide.