Patent ID: 6583537
Filing Date: 2003-06-24
Classification: H01T

Abstract:
A spark plug with a built-in resistor, which comprises:an insulator having an axially extending passing-through-hole; a terminal metal fitting fixed within the passing-through-hole at an end thereof; a center electrode fixed within the same passing-through-hole at the other end thereof; and a resistor provided between said terminal metal fitting and said center electrode within said passing-through-hole, said resistor comprising a resistor composition which is a mixture of a glass material portion and an electrically conductive material portion, wherein at least one of said terminal metal fitting and said center electrode is formed with a surface layer with a thickness of 0.1 to 100 &mgr;m facing said resistor, said surface layer being a metallic layer comprising at least one selected from the group consisting of Zn, Sn, Pb, Rh, Pd, Pt, Cu, Au, Sb and Ag, and a Ni alloy comprising at least one of B and P, wherein said at least one of said terminal metal fitting and said center electrode is directly in contact with said resistor on the surface of said metallic layer.