A protection device comprises a substrate, a fusible element and a heating element. The substrate comprises a first electrode and a second electrode on its surface. The fusible element is disposed on the substrate and connects to the first electrode and the second electrode at two ends. The fusible element comprises a first metal layer and a second metal layer disposed on the first metal layer. The second metal layer has a lower melting point than that of the first metal layer. The heating element is disposed on the substrate. In the event of over-voltage or over-temperature, the heating element heats up to melt and blow the fusible element. The second metal layer is 40-95% of the fusible element in thickness.

An interrupter includes a gas producer, an actuator pin, and an electrical conductor. The electrical conductor includes a first terminal portion, a first separable portion, a second terminal portion, and a second separable portion. The second separable portion is electrically connected to the first separable portion in parallel. A first timing when the first separable portion starts to be cut off from the first terminal portion is earlier than a second timing when the second separable portion starts to be cut off from the second terminal portion.

A protection element (10) of the present invention has a substrate (11), a first fuse element (12) and a second fuse element (13) connected in series on the substrate (11), a heater (14) connected between the first fuse element (12) and the second fuse element (13), a third upper electrode part (17) connected between the first fuse element (12) and the second fuse element (13) and connected to the heater (14) in series, a first conduction part (18) connected to the third upper electrode part (17) and having a lower resistance value than the heater (14), and a third lower electrode part (19) connected to the first conduction part (18) and configured to be connectable to an external protection circuit.

A chip-type fuse has a substrate. Two pads are disposed over a first side of the substrate. At least one fusible element is disposed over the first side of the substrate and electrically connects to the pads. A protective layer covers the first side of the substrate and the fusible element. The fusible element has a cross-section that is substantially circular, so the time durations for heat conduction from the center to points on the radial edge at the cross-section of the fusible element are almost equal. Thus, the fusible element can be uniformly heated. Therefore, when the circuit is overheated, the blow of the fusible element is uniform, which may effectively interrupt the circuit and protect the circuit.

A protection device comprises a substrate, a fusible element and a heating element. The substrate comprises a first electrode and a second electrode on its surface. The fusible element is disposed on the substrate and connects to the first electrode and the second electrode at two ends. The fusible element comprises a first metal layer and a second metal layer disposed on the first metal layer. The second metal layer has a lower melting point than that of the first metal layer. The heating element is disposed on the substrate. In the event of over-voltage or over-temperature, the heating element heats up to melt and blow the fusible element. The second metal layer is 40-95% of the fusible element in thickness.

An interrupter includes a gas producer, an actuator pin, and an electrical conductor. The electrical conductor includes a first terminal portion, a first separable portion, a second terminal portion, and a second separable portion. The second separable portion is electrically connected to the first separable portion in parallel. A first timing when the first separable portion starts to be cut off from the first terminal portion is earlier than a second timing when the second separable portion starts to be cut off from the second terminal portion.

A protection element (10) of the present invention has a substrate (11), a first fuse element (12) and a second fuse element (13) connected in series on the substrate (11), a heater (14) connected between the first fuse element (12) and the second fuse element (13), a third upper electrode part (17) connected between the first fuse element (12) and the second fuse element (13) and connected to the heater (14) in series, a first conduction part (18) connected to the third upper electrode part (17) and having a lower resistance value than the heater (14), and a third lower electrode part (19) connected to the first conduction part (18) and configured to be connectable to an external protection circuit.