| 摘要 |
Peeling (detachment) and deformation and the like of a chip is effectively prevented. A spark plug 1 is provided with: a central electrode 5; a ground electrode 27 forming a spark discharge gap 33 with the center electrode 5; and a chip 31(32) welded to at least one of the electrodes 5 and 27. The chip 31(32) has a thermal expansion coefficient smaller than a thermal expansion coefficient of the electrode 27(5) to which the chip is welded, and the difference between the content A (mass%) of a noble metal component in the chip 31 (32) and the content B (mass%) of a noble metal component in the electrode 27(5) (A - B) is 50 mass% or more. In an intermediate layer 34(35) between the chip 31(32) and the electrode 27(5), holes 38(39) are present. When the length of a boundary between the chip 31(32) and the intermediate layer 34(35) is L (mm), and the length of the holes 38(39) in a direction along the boundary of the chip 31 (32) and the intermediate layer 34(35) is N (mm), 0.1 ‰¤ N/L ‰¤ 0.4. |
