An electronic device includes an input, an output, a metal fuse, a resistor, a heat control transistor, and a heat controller. The metal fuse is coupled between the input and the output. The resistor is coupled between the metal fuse and the heat control transistor. The heat control transistor is coupled between the resistor and a reference terminal of the electronic device, and the heat controller is configured to control a heater current of the heat control transistor.

A flexible thin sheet-shaped electric wire includes: a body part having electrical insulation; and a conductor part that is arranged in the body part. Further, the conductor part includes a conductor body, and a fuse part that is formed in a part of the conductor body and of which a cross-sectional area is smaller than a cross-sectional area of the conductor body. Still further, the body part includes a conductor region in which the conductor body is arranged and a fuse region in which the fuse part is arranged. The fuse part includes an enclosing part that is arranged to enclose the entire circumference of at least a part of the fuse region.

This protection element (100) has a fuse element (3), an insulating inorganic fibrous material (4) that is disposed in contact with or close to at least a part of the fuse element (3), and a case member (5) configured to enclose a part of the fuse element (3) and the insulating inorganic fibrous material (4).

A protection device comprises a first substrate, a second substrate, a fusible element and a heating element. The first substrate comprises a first surface, and the second substrate comprises a second surface facing the first surface. The fusible element is disposed on the first surface of the first substrate, and the heating element is disposed on the second surface of the second substrate and is disposed above the fusible element. When over-voltage or over-temperature occurs, the heating element heats up to blow the fusible element and thereby providing over-voltage and over-temperature protection.

A fuse element (10) includes a low-melting-point metal layer (11), a high-melting-point metal layer (12) laminated on at least one surface of the low-melting-point metal layer (11), and an intermediate layer (13) disposed between the low-melting-point metal layer (11) and the high-melting-point metal layer (12), in which the high-melting-point metal layer (12) and the intermediate layer (13) are layers formed of a metal which is melted by a molten material of the low-melting-point metal layer (11), and the intermediate layer (13) has a higher ionization tendency than an ionization tendency of the high-melting-point metal layer (12).

An electronic device includes an input, an output, a metal fuse, a resistor, a heat control transistor, and a heat controller. The metal fuse is coupled between the input and the output. The resistor is coupled between the metal fuse and the heat control transistor. The heat control transistor is coupled between the resistor and a reference terminal of the electronic device, and the heat controller is configured to control a heater current of the heat control transistor.

A thermal protection device, comprising: a first PTC device, arranged in a PTC circuit, and having a first input side, coupled to an input path of the PTC circuit, and having a first output side, coupled to an output path of the PTC circuit; a second PTC device, arranged in the PTC circuit, and having a second input side, coupled to the input path of the PTC circuit, and having a second output side, coupled to the output path of the PTC circuit; and a thermal link having a third input side, coupled to the first output side of the first PTC device and the second output side of the second PTC device, via the output path of the PTC circuit.

A protective element (30) includes an insulating substrate (33), a plurality of electrodes (34) provided on the insulating substrate (33), a fuse element (35) electrically connected to any electrode (34) of the plurality of electrodes (34), and a heat generation element (38) provided on the insulating substrate (33) for heating and fusing the fuse element (35). The fuse element (35) contains a composite metal material in which a first fusible metal (31) and a second fusible metal (32) are stacked, some of a component of the first fusible metal (31) being dissolved at a joint working temperature, the second fusible metal (32) being lower in melt temperature than the first fusible metal (31), at least some of a component of the second fusible metal (32) being molten at the joint working temperature.

A protective element includes: a fuse element cuttable by energization in a first direction; a slider made of an insulating material, including: a plate-shaped portion extending in the first direction; a shielding portion erected in a second direction on the plate-shaped portion, having a shielding-portion through hole penetrating the shielding portion; and a case made of an insulating material, including a housing portion which houses a slider and a portion of the fuse element. The housing portion includes: a shielding-portion housing space which houses the shielding portion such that the shielding portion is movable in the second direction; and a plate-shaped-portion moving space which houses the plate-shaped portion such that the plate-shaped portion is movable in the second direction Prior to the fuse element being cut, the slider and the fuse element are housed such that the fuse element is inserted into the shielding-portion through hole.

A fuse element includes: a low-melting-point metal layer; a high-melting-point metal layer provided over at least one surface of the low-melting-point metal layer; and an intermediate layer disposed between the low-melting-point metal layer and the high-melting-point metal layer. Each of the high-melting-point metal layer and the intermediate layer is made of a metal that is liquefied by contacting a molten form of the low-melting-point metal layer. The high-melting point metal layer is made of silver or an alloy comprising silver as a main component thereof. A melting point of a material constituting the intermediate layer is higher than a melting point of a material constituting the low-melting-point metal layer and lower than a melting point of a material constituting the high-melting-point metal layer.