PURPOSE: To increase a contact area and assure a rapid operation of a flat thermal fuse by a method wherein a metallic plate of the flat thermal fuse is contacted with a heat shielding plate at a rear surface of a dimple part having metallic soluble wires of low melting point and at the same time contacted with the heat shielding plate also at the rear surface part of the dimple part.

CONSTITUTION: A plurality of dimple stripes 13 held between a of projections 12 and 12 are press formed in parallel from each other at one surface of a metallic plate 1 having an insulating thin film 11 of better heat transfer characteristic at least one surface and at the same time some dimple portions 130 are press formed between the adjoining groups of projections 12. Soluble metallic wires 6 of low melting point are stored in the dimple stripes 13 through flax, both ends of each of the soluble metallic wires 6 are connected to an end part of a bridge conductive member with a soldering and the like and at the same time resin sealing material such as epoxy resin is molded to the dimple stripes 13 so as to constitute a desired flat thermal fuse. Then, the other surface of the metallic plate 1 is contacted with and fixed to a heat shielding plate 98 and then the dimple part 13 and the rear surface of the dimple part 130 are closely contacted with the rear surface of the heat shielding plate 98 and then the fuse is fixed.