| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a further larger stress relaxation effect without increasing a manufacturing cost.SOLUTION: A silicon tube 5 is provided with a first columnar portion 5-1 which is formed from an upper end surface (a first end surface) 5a toward a lower end surface (a second end surface) 5b, and has a first length L1 in an axial direction; a second columnar portion 5-2 which is formed from the lower end surface (the second end surface) 5b toward the upper end surface (the first end surface) 5a, and has a second length L2 in the axial direction; and a square columnar portion 5-3 which has a third length L3 between the first columnar portion 5-1 and the second columnar portion 5-2. A diameter D1 of the first columnar portion 5-1 and a diameter D2 of the second columnar portion 5-2 are made to be smaller than the width (vertical width and lateral width) W of the square columnar portion 5-3.</p> |
