PURPOSE: To obtain a circuit board which is excellent in terms of thermal conductivity and insulation properties and a circuit board capable of bonding with a conducting layer more powerfully by previously forming a metal Al layer on a reserved site electrode wiring on said aluminum nitride board.

CONSTITUTION: An intensive high energy wave is irradiated to an aluminum nitride board in order to generate a metal Al layer on a specified position. Laser light or electron beam is used as the intensive high energy wave. More specifically, Q switch originating YAG laser is used for the high energy wave. The irradiation conditions include output of 10W, Q rate of 9kHz, and beam size of about 200μm, and irradiation speed of 1.5mm/s under the nitrogen atmosphere. This beam is irradiated vertically to the aluminum nitride board so that the whole surface area of a 2mm×2mm portion may be turned into metal Al. At that time, the metal Al layer was about 3μm, where the decomposition reaction was carried out, say, from 2AlN to 2Al+N2↑.