PURPOSE: To lower the resistance of conductor circuits comprising tungsten as well as facilitating the latter step such as polishing, etc., after baking step.

CONSTITUTION: A paste P1 containing tungsten particles in mean particle diameter of 1.1μm as well as another paste P2 containing tungsten particles in mean particle diameter of 0.4μm are manufactured. After the formation of conductor circuits 3a, 3b using the paste P1 on aluminum nitride made green sheets 1, respective green sheets are laminated. Next, a dummy green sheet 1a is arranged on the outermost layer of the green sheets 1 through the intermediary of a carbon absorbed layer L comprising the paste P2. At this time, two kinds of green sheets 1, 1a are pressure-fixed. Later, after finishing the tack-baking step at the lower temperature than the sintering temperature of the aluminum nitride, the regular baking step is to be performed.