Patent ID: 6863586

Claim:
A manufacturing method for a sealing plug used in sealing an arc tube, the sealing plug being formed by sintering a preform structured from a plurality of layers, the layers of the preform being layered around an outer circumference of a metal lead wire that supplies power to electrodes within the arc tube, so that the layers are substantially concentric with respect to the metal lead wire, comprising: a slurry preparation step of preparing slurries used in forming the layers of the preform, the slurries corresponding one-to-one with the layers; and a preform manufacturing step of manufacturing the preform by dipping the metal lead wire into the slurry used to form an inner-most layer and drying the slurry adhering to the metal lead wire, and repeating the dipping and drying sequentially for the slurries used to form a second layer to an outer-most layer, wherein the slurry preparation step has the substep of: preparing a slurry that includes a readily decomposable organic material, and the preform manufacturing step has the sub step of: prior to forming at least one of the layers of the preform, forming an organic layer by dipping the metal lead wire into the slurry that includes the readily decomposable organic material, and drying the adhering slurry, and the organic layer becomes a gap layer after sintering.