In order to obtain ceramic substrates for multilayer interconnections in microelectronic devices corundum-glass composites of the Keramovitron type were combined with silver or silver-palladium alloys by low-temperature co-firing below 1000°C. To understand the reactions occurring at the phase borders glass/corundum and glass/metal both model samples and metallized laminates were studied, preferably by electron probe microanalysis. The distribution of the elements aluminium, potassium, silicon and silver, determined by point, linear and area analyses, speaks in favour of diffusion of potassium from the glass melt to the boundary layers, whereas aluminium and silver migrate into the glassy phase.