| 摘要 |
PROBLEM TO BE SOLVED: To enable a ceramic circuit board to be improved in the withstand voltage characteristic and protected against cracking which occurs when the board is mounted and put in operation, by a method wherein an alumina board whose alumina purity is above a specified value is used as a ceramic board, and voids of the alumina board are set smaller than a prescribed value. SOLUTION: A ceramic circuit board 1 is composed of a ceramic board 2 and a metal circuit board 3 of prescribed shape bonded to the board 2. An alumina board whose alumina purity is above 99.5% and void content is below 5 vol.% and which has few defects is used as the ceramic board 2. By this setup, the ceramic board 2 is enhanced enough in denseness even if a small amount of sintering auxiliary is used and becomes higher in thermal conductivity than a conventional alumina board. The alumina board itself is lessened in thickness so as to be reduced in heat resistance. A circuit board more excellent in heat dissipating properties can be formed by synergism of these effects.
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