Patent ID: 7446993

Claim:
An alumina sintered body comprising: an alumina substrate having a first main surface and a second main surface opposing each other; an embedded film electrode made of a metal and embedded in the alumina substrate at a depth of 0.4 mm or less from the first main surface; and an embedded terminal formed of a metal, embedded in the alumina substrate nearer the second main surface side than the embedded electrode, the embedded terminal being positioned at the base of a hole having a diameter larger than the embedded terminal, an outer peripheral portion of the embedded terminal being chamfered or radiused at a contact surface at which the embedded terminal is in contact with the embedded electrode, wherein a portion of the embedded electrode positioned on the contact surface between the embedded terminal and the embedded electrode is alloyed with the embedded terminal by integrally sintering the embedded terminal and electrode, and wherein a film thickness of the embedded electrode is 25 μm or less.