PURPOSE: To extremely reduce possibility of a short-circuit by so forming a thick film conductor as to be partly superposed on a connecting conductor when the conductor is formed through a connecting conductor layer formed after an antioxidation barrier layer is provided to be superposed on the conductor exposed part

CONSTITUTION: An insulating layer 10 made of a ceramic green sheet is prepared, insulating layers 12, 14 made of insulating paste containing the same components as those of the sheet as main materials, and conductor layers 16, 18, 20 made of conductive paste containing high melting point metal such as tungsten, molybdenum, etc., as main ingredients are alternately printed and laminated, simultaneously baked to form a ceramic board 24 having a conductor exposed part 22. After antioxidation barrier layer 25 made of a nickel-plated layer and melted noble metal is formed on the part 22 of the board 24, a connecting conductor 28 made of noble metal thick film conductor, etc., is, for example, screen-printed, and further baked. A thick film conductor 30 is so formed as to partly superpose it on the part of the conductor 28.