Abstract: A ceramic-metal lead assembly, of the type suitable for use in nerve or heart pacemakers, has a disk of high-purity ceramic with at least one lead extending therethrough, the disk being soldered vacuum-tight to a flange ring via a solder gap. The flange ring consists of a metal which is resistant to body electrolytes, and the coefficients of thermal expansion of the joined materials are matched to each other, but are not identical. For avoiding cracks in the ceramic disk in the region of the solder connection, the solder gap has a width such that the diffusion path of the metal of the flange ring into the solder connection cannot exceed a selected distance in the solder bridge which forms at the soldering temperature. A solder zone which is free of the metal of the flange ring, and thus has a dutility which is not degraded by the flange ring metal, is formed around the ceramic disk.