Abstract: A thick-film circuit on a ceramic substrate has circuit paths on opposite sides thereof interconnected with one another by through holes in the substrate filled with a paste which includes grains of a refractory material therein. After sintering, a conductive path results which is substantially non-shrinking. The through holes are preferably filled using a device having a pair of resilient doctor blades arranged to form a V-shaped groove therebetween. An amount of such conductive paste is placed in the groove and a substrate with through holes therein is advanced through the V-shaped groove so that the paste is squeezed into the through holes and the flat surfaces of the substrate are wiped clean by the doctor blades.