| 摘要 |
PROBLEM TO BE SOLVED: To provide a hard brittle material sheet with a through hole hard to be broken even by treatment where, e.g., it is grasped and moved. SOLUTION: The hard brittle material sheet 5 is provided with a through hole 17 formed by being passed through front surface and back surface 5a, 5b. Since at least a part of the inner circumferential face of the through hole 17 is a curved face part in which the tilt of the tangent continues along the passing through direction, the inner circumferential area of the through hole 17 is larger than the rectilinear inner circumferential face along the passing through direction, and, in the through hole 17 on which a bending load applied to the hard brittle material sheet 5 is easy to be concentrated, not only the stress acted on the inner circumferential face of the through hole 17 can be suppressed but also, in the curved face part, corner parts are not present, and the stress by the bending load is not locally applied but is dispersed. Thus, the hard brittle material sheet 5 is hard to be broken to the bending load. COPYRIGHT: (C)2009,JPO&INPIT
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