Patent ID: 8184429

Claim:
A capacitor comprising: a lead wire including an aluminum wire round rod, a metal cap having a concave-shaped cross section, an opening, and a dome-shaped end portion, the dome-shaped end portion and the opening being at opposite ends of the metal cap, the opening being fitted to an end portion of the aluminum wire round rod, wherein an outer diameter of a curved surface which forms the dome-shaped end portion increases along a direction from the dome-shaped end portion toward the opening, the outer diameter being a smallest outer diameter at the dome-shaped end portion, and being a largest outer diameter at an end provided with the opening; an alloy diffusion layer between the aluminum wire round rod and the metal cap, the alloy diffusion layer joining the aluminum wire round rod and the metal cap, and an external terminal joined to the metal cap on an outer surface at the dome-shaped end portion; a capacitor element coupled to the aluminum wire round rod of the lead wire; an exterior case having a cylindrical shape with a bottom and accommodating the capacitor element; and a sealing member provided with a through-hole allowing the lead wire to pass through and sealing an open end of the exterior case, wherein the external terminal of the lead wire protrudes from the through-hole in the sealing member.