PURPOSE: To break a circuit instantaneously when abnormal generation of heat occurs, and thereby to enable confirming the occurrence of an abnormal state with eyesight easily, by fixing an elastic terminal wire with a low temperature molten metal, having its prolonged end deformed elastically to the side of the terminal attached to the other electrode, and fixing it to a circuit substrate.

CONSTITUTION: An elastic terminal wire 5 is made of a reed-shaped body whose material is rich in elasticity like phosphor bronze. One end of the wire 5 is fixed with a low melting point metal, conceretely solder 6, to one electrode 4b of an element chip 3, a varister etc., fixed to a heat sink plate 2. The elastic terminal wire 5 soldered to the electrode 4b, is properly deformed by bending so as to be able to be easily deformed elastically, and the other end is prolonged and fixed, in the same direction as the terminal 1 of the plate 2 and in an opening out direction. The elastic terminal wire 5 loses its holding force by the melting of the solder 6, and separates from the front electrode 4b of the element chip 3 by its own repulsive force, with the fixed part of the substrate being an axis, to break a circuit.