PURPOSE: To form a circuit accurately by bonding a metallic circuit, obtained by removing the parts other than a circuit pattern from a detachable metal foil holding the circuit pattern, to the upper and lower surfaces of a ceramic board.
CONSTITUTION: A metal foil 1, from which circuit patterns 2, 3 are punched by press, is fitted to the original position on the upper surface of an aluminium nitride board coated with a binder paste whereas a trimmed metal foil 5, from which a planar circuit pattern 6 is punched by press, is fitted to the original position on the lower surface of the board. It is then placed in a furnace thus producing a bonded body. The bonded body is then manually peeled off at the part not bonded with the aluminium nitride board, i.e., the part other than the circuit pattern, and then a copper circuit and a planar copper circuit are formed, respectively, on the upper and lower surfaces of the aluminium nitride board.
NAKAMURA YOSHIYUKI
UCHINO KOICHI
TERANO KATSUNORI
