TWI655662B - Switching element, switching circuit, and alarm circuit - Google Patents

Abstract

A switching element provided by the present invention includes a fusible conductor, a first electrode connected to one end portion of the fusible conductor, a second electrode connected to the other end portion of the fusible conductor, and High melting point metal body.

Description

Switching element, switching circuit, and alarm circuit

The present technology relates to a switching element, a switching circuit, and an alarm circuit using the same, and more particularly to a switching element, a switching circuit, and an alarm circuit using the same that can be miniaturized and can be easily incorporated into a driving circuit by surface mounting.

As a switching element for activating an alarm, an alarm fuse is generally used (see Patent Document 1). As an example of an alarm fuse, as shown in FIGS. 15A and 15B, a pair of alarm contacts 101 and 102, a spring 103 that contacts the alarm contacts 101 and 102, and a holding spring 103 are provided in the fuse holder 100. Fuse line 104. The pair of alarm contacts 101 and 102 is connected to the alarm circuit 105 which activates the alarm and is usually arranged at a distance from each other. The fuse 104 biases the spring 103 at a position spaced from the alarm contact 102.

The alarm contacts 101 and 102 activate the alarm circuit 105 by contacting each other. The alarm contacts 101 and 102 are formed of a conductive material such as a leaf spring having elasticity and are arranged close to each other. The alarm circuit 105 activates the alarm system. The activation of the alarm system is, for example, activation of a buzzer or a lamp, driving of a thyristor or a relay circuit, and the like.

The spring 103 is held in a biased state by the fuse 104 at a position spaced from the alarm contact 102. Then, since the spring 103 recovers its elasticity due to the melting of the fuse 104, the alarm contact 102 is pressed to bring the alarm contact 102 into contact with the alarm contact 101.

The fuse 104 holds the spring 103 in an elastically deformed state, and by using and An overcurrent that exceeds the rated current flowing into the fusible link 104 self-heats and melts, and the spring 103 is opened.

[Advanced technical literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2001-76610

In the above-mentioned warning fuse, the fuse 103 is used to hold the spring 103 in an elastically deformed state. In addition, by melting the fuse 104 and releasing the stress of the spring 103, the alarm contact 102 is physically pressed to cause a short circuit between the alarm contacts 101 and 102. In such an alarm fuse, since the alarm circuit is activated by the physical linkage of mechanical elements, it is necessary to ensure the movable range of the alarm contacts 101, 102 and the spring 103, so that the configuration of the alarm fuse becomes larger. Therefore, it becomes difficult to use the above fuse in a miniaturized circuit. In addition, production costs have also increased.

In addition, since it is necessary to blow the fuse 104 to short-circuit the alarm contacts 101 and 102, it is difficult to activate the alarm circuit unless the fuse 104 is blown without continuously passing a rated current.

Further, in the above-mentioned alarm fuse, the alarm circuit is activated by short-circuiting the alarm contacts 101 and 102 which are normally open. Therefore, for example, in order to perform an alarm operation such as turning off an indicator lamp which is lit during a normal time during an abnormal state, the fuse cannot be used.

Therefore, it is desirable to provide a switching element and a switching circuit that interrupt external circuits such as an alarm circuit during an abnormality, do not rely on physical interlocking of mechanical elements, and quickly stop power supply to the circuit. Alarm circuit.

In order to solve the above problems, a switching element according to an embodiment of the present technology includes a fusible conductor, a first electrode connected to one end portion of the fusible conductor, a second electrode connected to the other end portion of the fusible conductor, and a ratio High melting point metal body with a high melting point.

A switch circuit according to an embodiment of the present technology includes a switch unit and a second fuse. The switch unit includes a first electrode and a second electrode which are connected to each other via an first fuse and to an external circuit, and interrupts the power supply to the external circuit by interrupting the current between the first electrode and the second electrode. The second fuse has a higher melting point than that of the first fuse, and is connected to a functional circuit that is electrically independent from the switch unit.

An alarm circuit according to an embodiment of the present technology includes a drive circuit, a second fuse, and a control circuit. The driving circuit includes a first electrode and a second electrode connected to each other via a first fuse, and interrupts the power supply to the alarm device by interrupting the current between the first electrode and the second electrode. The second fuse is electrically independent of the driving circuit and has a melting point higher than the melting point of the first fuse. This control circuit has a functional circuit in which a second fuse is connected in series to a power source.

A switching element, a switching circuit, or an alarm circuit according to an embodiment of the present technology can form a switching element without using mechanical elements such as springs and alarm contacts, and without relying on the physical linkage of the mechanical elements. , It is possible to design the switching element in a small size, and it is also possible to install the switching element in a miniaturized mounting area.

In addition, since the circuit that heats the high-melting-point metal body is electrically independent from the circuit on which the fusible conductor is mounted, and the heat of the high-melting-point metal body is used to fuse the fusible conductor, the melting of the high-melting-point metal body can be detected without the need An abnormal overcurrent causes the circuit to start, and also suppresses the influence of noise generated when the high-melting-point metal body is fused.

In addition, it is possible to surface mount an insulating substrate or the like by reflow soldering, and it is easy to mount even in a small mounting area.

1,40,50‧‧‧Switching element

10‧‧‧ Insulated substrate

10a‧‧‧ surface

10f‧‧‧ back

11‧‧‧The first electrode

12‧‧‧Second electrode

13‧‧‧ Fusible Conductor

15‧‧‧ high melting point metal body

16‧‧‧ Insulation

18‧‧‧Flux

19‧‧‧ Connection Department

20‧‧‧ cover member

21‧‧‧ sidewall

22‧‧‧Top Facial

23‧‧‧ cover electrode

30‧‧‧Alarm circuit

31‧‧‧Alarm

32‧‧‧Function Circuit

35‧‧‧The first fuse

36‧‧‧ 2nd fuse

FIG. 1A is a plan view showing a state before a switching element according to an embodiment of the present technology is activated.

FIG. 1B is a cross-sectional view of the switching element shown in FIG. 1A, taken along line AA ′.

FIG. 1C is a circuit diagram of the switching element shown in FIG. 1A.

FIG. 2A is a plan view showing a state of a switching element in which a high-melting-point metal body generates heat, a fused conductor of a fusible conductor is fused, and the current between the first and second electrodes is cut off.

FIG. 2B is a cross-sectional view of the switching element shown in FIG. 2A, taken along line AA ′.

FIG. 2C is a circuit diagram of the switching element shown in FIG. 2A.

3A is a plan view showing a state of a switching element in which a refractory metal body is blown.

FIG. 3B is a cross-sectional view of the switching element shown in FIG. 3A, taken along line AA ′.

FIG. 3C is a circuit diagram of the switching element shown in FIG. 3A.

Fig. 4 is a circuit diagram showing an alarm circuit.

5A is a plan view showing a switching element in which a refractory metal body and a first electrode are connected to each other.

FIG. 5B is a cross-sectional view of the switching element shown in FIG. 5A, taken along line AA ′.

FIG. 5C is a circuit diagram of the switching element shown in FIG. 5A.

6 is a cross-sectional view showing a switching element in which a cover electrode is formed on a cover member.

7A is a plan view showing a switching element in which a refractory metal body, a first electrode, and a fusible conductor overlap each other on the surface of an insulating substrate.

FIG. 7B is a cross-sectional view of the switching element shown in FIG. 7A, taken along line AA ′.

FIG. 8A is a plan view showing a high-melting-point metal body formed on the back surface of an insulating substrate, and a first electrode formed on the surface of the insulating substrate and a switching element in which a fusible conductor and the high-melting metal body overlap each other.

FIG. 8B is a cross-sectional view of the switching element shown in FIG. 8A, taken along the line AA ′.

FIG. 9A is a perspective view of a fusible conductor having a coating structure including a high-melting-point metal layer and a low-melting-point metal layer, and shows a case where a high-melting-point metal layer is used as an inner layer and the high-melting-point metal layer is covered with a low-melting-point metal layer.

FIG. 9B is a perspective view of a fusible conductor having a coating structure including a high-melting-point metal layer and a low-melting-point metal layer. FIG.

FIG. 10A is a perspective view showing a fusible conductor having a laminated structure of a high-melting-point metal layer and a low-melting-point metal layer, and shows a case where the fusible conductor has a two-layer structure.

FIG. 10B is a perspective view showing a fusible conductor having a laminated structure of a high melting point metal layer and a low melting point metal layer, and shows a case where the fusible conductor has a three-layer structure composed of an inner layer and two outer layers.

11 is a cross-sectional view showing a fusible conductor having a multilayer structure having a high-melting metal layer and a low-melting metal layer.

FIG. 12A is a plan view of a fusible conductor in which linear openings are formed on the surface of the high-melting-point metal layer, and the low-melting-point metal layer is exposed at the openings, and shows a case where openings are formed along the longitudinal direction.

FIG. 12B shows the formation of linear openings on the surface of the high-melting-point metal layer, and low-melting-point gold. A plan view of the fusible conductor with the metal layer exposed at the opening shows a case where an opening is formed in the width direction.

FIG. 13 is a plan view showing a fusible conductor in which a circular opening is formed on the surface of the high-melting-point metal layer, and the low-melting-point metal layer is exposed through the opening.

14 is a plan view showing a fusible conductor in which a circular opening is formed in a high-melting-point metal layer, and a low-melting metal layer is filled in the opening.

15A is a cross-sectional view showing a state before activation of an example of an alarm element.

15B is a cross-sectional view showing a state after activation of an example of the alarm element.

Hereinafter, a switching element, a switching circuit, and an alarm circuit according to an embodiment of the present technology will be described in detail with reference to the drawings. In addition, the present technology is not limited to the following embodiments, and various changes can be made to the present technology without departing from the spirit of the present technology. In addition, the drawings are schematic, and ratios of dimensions may be different from actual ones. Specific dimensions should be considered and judged according to the following description. It is needless to say that the drawings include portions having different dimensional relationships and ratios.

As shown in FIGS. 1A to 1C, a switching element according to an embodiment of the present technology includes an insulating substrate 10, first and second electrodes 11 and 12 formed on the insulating substrate 10, and first and second electrodes 11 and 2 connected to the first and second electrodes 11 and 12. The fusible conductor 13 of the electrode 12 and the high-melting-point metal body 15 formed on the insulating substrate 10 and having a melting point higher than the melting point of the fusible conductor 13. In addition, FIG. 1A is a plan view of the switching element 1 without the cover member 20, FIG. 1B is a cross-sectional view of the switching element 1 along the AA ′ line shown in FIG. 1A, and FIG. 1C is a circuit diagram of the switching element 1.

The switching element 1 passes the first electrode 11 and the second electrode 12 and the buzzer and the lamp. An alarm device 31 (FIG. 4 to be described later) constituted by an alarm system or the like is connected. This switching element 1 stops the current flow between the first electrode 11 and the second electrode 12 by melting the fusible conductor 13 with heat generated by an overcurrent exceeding the rated current flowing into the high-melting-point metal body 15, thereby stopping the conduction between the first electrode 11 and the second electrode 12. The alarm 31 is powered on, and the indicator light is turned off. In addition, after the switching element 1 interrupts the conduction between the first electrode 11 and the second electrode 12, the high-melting-point metal body 15 is fused to stop the heat generation.

[Insulating substrate]

The insulating substrate 10 is formed using, for example, an insulating material such as alumina, glass ceramic, mullite, and zirconia. In the switching element 1, since the heat generated by the high-melting-point metal body 15 is transmitted to the first electrode 11, the second electrode 12, and the fusible conductor 13 through the insulating substrate 10, the insulating substrate 10 preferably has excellent heat resistance and A material having a high thermal conductivity, such as a ceramic substrate, is formed. In addition, the insulating substrate 10 may be formed of a material used for a printed wiring board such as a glass epoxy substrate, a phenol substrate, or the like, but it is necessary to pay attention to the temperature at which the high-melting metal body 15 and the fusible conductor 13 are fused.

[First and second electrodes]

The first electrode 11 and the second electrode 12 are arranged opposite to each other on the surface 10 a of the insulating substrate 10 and spaced apart from each other. The front end portion 11b of the first electrode 11 and the front end portion 12b of the second electrode 12 face each other, and a fusible conductor 13 described later is connected to the front end portions 11b and 12b. Specifically, the front end portion 11 b of the first electrode 11 overlaps one end portion of the fusible conductor 13 and is connected to one end portion of the fusible conductor 13. The front end portion 12 b of the second electrode 12 overlaps the other end portion of the fusible conductor 13 and is connected to the other end portion of the fusible conductor 13. The first electrode 11 and the second electrode 12 are electrically connected to each other through a fusible conductor 13. If heat is generated when the high-melting metal body 15 is energized, the fusible conductor 13 is heated by the heat, and the fusible conductor 13 is blown.

In addition, the first electrode 11 and the second electrode 12 are heated by the high-melting-point metal body 15, so that the melt (melt conductor) of the fusible conductor 13 can be easily aggregated.

The first electrode 11 has an external connection terminal 11 a on a side 10 b of the insulating substrate 10, and the second electrode 12 has an external connection terminal 12 a on a side 10 c of the insulating substrate 10. The first electrode 11 and the second electrode 12 are connected to the alarm device 31 via external connection terminals 11 a and 12 a, and the power supply to the alarm device 31 is blocked by the operation of the switching element 1.

The first electrode 11 and the second electrode 12 are formed of a general electrode material containing at least one of copper (Cu), silver (Ag), or the like as a constituent element thereof, for example, a refractory metal. Each of the first electrode 11 and the second electrode 12 is an electrode pattern that is patterned by the same method as the high-melting-point metal body 15 described later. In addition, on the surfaces of the first electrode 11 and the second electrode 12, a coating containing nickel (Ni) / gold (Au) plating, Ni / palladium (Pd) plating, Ni / Pd / Au plating, or the like is preferably used. And other known methods. Therefore, in the switching element 1, the oxidation of the first electrode 11 and the second electrode 12 can be prevented, and the molten conductor of the fusible conductor 13 on the first electrode 11 and the second electrode 12 can be reliably maintained. In addition, when the switching element 1 is mounted by reflow soldering, it is possible to prevent the first electrode 11 and the first electrode 11 from being melted by a connection solder for connecting the fusible conductor 13 or a low-melting-point metal for forming an outer layer of the fusible conductor 13. 2 The electrode 12 is eroded (solder leaching).

[High melting point metal body]

The high-melting-point metal body 15 is formed of a conductive material that generates heat upon application of electricity, for example, a high-melting-point metal containing at least one of tungsten (W), molybdenum (Mo), ruthenium (Ru), Cu, and Ag as a constituent element. The conductive material may be an alloy. The high-melting-point metal body 15 is formed by mixing a powder of these alloys or compositions and compounds with a resin binder to form a conductive paste, and patterning the conductive paste using a screen printing technique, followed by firing or the like. Electrode pattern.

The high-melting-point metal body 15 is arranged in parallel with the first electrode 11 and the second electrode 12 on the surface 10 a of the insulating substrate 10. Therefore, the high-melting-point metal body 15 can melt the fusible conductor 13 disposed on the first electrode 11 and the second electrode 12 if it generates heat with the application of electricity.

The high-melting-point metal body 15 has external connection terminals 15 a on the sides 10 b and 10 c of the insulating substrate 10, respectively. The high-melting-point metal body 15 is connected to the functional circuit 32 that triggers the alarm 31 via an external connection terminal 15a, and generates a high temperature due to the overcurrent exceeding the rated current accompanying the abnormality of the functional circuit 32, causing the fusible conductor 13 to blow. For example, the high-melting-point metal body 15 can be designed with electric power that generates heat of about 300 ° C. by applying electric power of 20 W to 30 W.

Further, in the high-melting-point metal body 15, a portion is tapered at a position close to the fusible conductor 13. At the position where the high-melting-point metal body 15 is partially thinned, a heat generating portion that locally generates heat due to current concentration is formed. 15b. By providing the heat generating portion 15 b at a position close to the fusible conductor 13, the high-melting-point metal body 15 can effectively melt the fusible conductor 13, and at the same time, can quickly shield the current between the first electrode 11 and the second electrode 12. Off.

In the switching element 1, as shown in FIG. 1A to FIG. 1C, a position close to one of the first electrode 11 and the second electrode 12 is located at the front end of the switching element 1 before the first electrode 11 connected to the fusible conductor 13. It is preferable that the heating portion 15b of the refractory metal body 15 is formed at a position close to 11b. By providing the heat generating portion 15b at a position close to the front end portion 11b of the first electrode 11 connected to the fusible conductor 13, the high-melting-point metal body 15 can efficiently transfer heat to the heat sink through the insulating substrate 10 and the front end portion 11b. The conductor 13 is melted and melted, and at the same time, the current between the first electrode 11 and the second electrode 12 can be quickly cut off.

The front end portion 11 b of the first electrode 11 connected to the fusible conductor 13 and the front end portion 12 b of the second electrode 12 connected to the fusible conductor 13 are preferably connected to the heat generating portion. The area of the front end of one side closer to 15b is larger than that of the other front end, and the electrode having the front end of the one side holds more fusible conductors 13 than the electrode having the front end of the other side. As shown in FIGS. 1A to 1C, in the switching element 1, when the heating portion 15 b of the refractory metal body 15 is brought close to the front end portion 11 b of the first electrode 11, it is preferably larger than the front end portion 12 b of the second electrode 12. The front end portion 11 b of the first electrode 11 is formed, and the fusible conductor 13 is connected to a wide range by the front end portion 11 b of the first electrode 11.

Since the front end portion 11b of the first electrode 11 is close to the heat generating portion 15b, more heat can be transmitted from the high-melting-point metal body 15 to the front end portion 11b, and the fusible conductor 13 can be effectively melted. Therefore, since the area of the front end portion 11b of the first electrode 11 is relatively enlarged and more fusible conductors 13 are held on the first electrode 11, it is possible to transfer heat to the fusible conductor 13 more quickly and This is melted, and at the same time, the conduction between the first electrode 11 and the second electrode 12 can be interrupted.

In addition, since the front end portion 11b of the first electrode 11 is close to the heat generating portion 15b and has a relatively large area, it can be heated to a higher temperature, so that most of the molten fusible conductor 13 can be maintained.

As shown in FIG. 1A to FIG. 1C, in the high-melting-point metal body 15, when the functional circuit 32 is normally operated, an appropriate current within the rated current flows. However, when an overcurrent exceeding the rated current flows in the high-melting-point metal body 15 due to an abnormality of the functional circuit 32, the high-melting-point metal body 15 generates heat due to heat generation, as shown in FIGS. 2A to 2C. 13 is blown, and at the same time, the current between the first electrode 11 and the second electrode 12 is blocked. After that, since the high-melting-point metal body 15 continues to generate heat, as shown in FIGS. 3A to 3C, the high-melting-point metal body 15 also fuses by its own heating (Joule heat). Therefore, the overcurrent caused by the abnormality of the functional circuit 32 is blocked, At the same time, the functional circuit 32 is blocked, so the high-melting-point metal body 15 stops its own heating. That is, the high-melting-point metal body 15 is used as a fuse that fuses the fusible conductor 13 and interrupts its own power supply path by self-heating.

In addition, the high-melting-point metal body 15 is provided with a heat-generating portion 15b that becomes locally high temperature, and the high-melting-point metal body 15 is fused at the heat-generating portion 15b. At this time, in the high-melting-point metal body 15, because the partially thinner heating portion 15b is formed, the arc discharge generated at the time of fusing also stays on a small scale, and at the same time, the covering effect of the insulating layer 16 described later can be obtained. It is possible to prevent scattering of the molten conductor.

In addition, in order to form the high-melting-point metal body 15, in addition to patterning the conductive paste using the printing method described above, a high-melting-point metal foil such as copper foil or silver foil or a high-melting-point metal wire such as copper wire or silver wire can be used to form a high-melting metal body. Melting point metal body 15. When the high-melting-point metal body 15 is formed using a high-melting-point metal foil or a high-melting-point metal wire, as the insulating substrate 10, if a ceramic substrate having excellent thermal conductivity and capable of rapidly melting the fusible conductor 13 is used, it is similar to using a conductive paste Compared with the case, the leakage problem of the molten conductor after the high-melting-point metal body 15 is fused is also reduced.

[Insulation]

The first electrode 11, the second electrode 12, and the refractory metal body 15 are covered with an insulating layer 16 on the surface 10 a of the insulating substrate 10. The insulating layer 16 is provided to protect and insulate the first electrode 11, the second electrode 12, and the high-melting-point metal body 15 while suppressing arc discharge when the high-melting-point metal body 15 is fused, and includes, for example, glass.

As shown in FIG. 1A to FIG. 1C, FIG. 2A to FIG. 2C, and FIG. 3A to FIG. 3C, the insulating layer 16 covers the heat generating portion 15b of the refractory metal body 15 and is formed at the ends other than the front ends of the first electrode 11 and the second electrode 12. Areas other than the sections 11b, 12b. That is, the first electrode 11 and the second electrode In 12, since the front end portions 11 b and 12 b are not covered with the insulating layer 16 and are exposed, a fusible conductor 13 described later can be connected to the front end portions 11 b and 12 b.

In addition, since the insulating layer 16 is formed in a region other than the front end portions 11 b and 12 b of the first electrode 11 and the second electrode 12, heat generated in the high-melting-point metal body 15 is transmitted to the front end portion 11 b through the insulating substrate 10. In the case of 12 and 12b, this heat can be prevented from being released, so the front end portions 11b and 12b can be effectively heated and the heat can be transferred to the fusible conductor 13. In addition, the first electrode 11 and the second electrode 12 are provided with an insulating layer 16 between the front end portions 11b and 12b and the external connection electrodes 11a and 12a, thereby preventing the externally connected electrode 11a from being melted by the fusible conductor 13 The 12a side flows out and the solder used to connect the circuit board on which the switching element 1 is mounted is melted.

Further, in the switching element 1, an insulating layer 16 containing glass or the like may be formed between the refractory metal body 15 and the insulating substrate 10. Therefore, in the switching element 1, the insulation resistance can be increased by preventing leakage due to adhesion of the molten conductor to the surface of the insulating substrate 10 after the high-melting-point metal body 15 is fused. Furthermore, by only partially disposing the insulating layer 16 formed between the high-melting-point metal body 15 and the insulating substrate 10 near the center of the heat generating portion 15b, it is possible to simultaneously ensure the performance of heat transfer to the fusible conductor 13 and Insulation resistance after blocking.

[Fusible conductor]

As a material for forming the fusible conductor 13 disposed on the first electrode 11 and the second electrode 12 with the insulating layer 16 interposed therebetween, it is preferable to use any metal (low melting point metal) that is rapidly melted by the heat generated by the high melting point metal body 15. The low-melting-point metal is, for example, solder, or solder that does not melt during reflow soldering at 260 ° C. with Pb as a main component.

The fusible conductor 13 may contain a low-melting metal and a high-melting metal. As the low melting point metal, solder or lead-free solder containing Sn as a main component is preferably used. As As the high-melting-point metal, a material containing at least one of Ag and Cu as its constituent element is preferably used. The high-melting-point metal may be an alloy or the like. Since the fusible conductor 13 contains a high-melting metal and a low-melting metal, when the switch element 1 is reflow-mounted, the low-melting metal can be suppressed even if the low-melting metal is melted because the reflow temperature exceeds the melting temperature of the low-melting metal. Since the outside flows out, the shape of the fusible conductor 13 can be maintained. In addition, since the low-melting-point metal is melted and the high-melting-point metal is eroded (solder leaching) at the time of fusing, the fusible conductor 13 can be quickly fused at a temperature below the melting point of the high-melting point metal. The fusible conductor 13 can be formed into various structures as described later.

The fusible conductor 13 is preferably coated with a flux 18 in order to prevent oxidation, improve wettability, and the like.

[Switch circuit‧Alarm circuit]

The switching element 1 described above has a circuit configuration as shown in FIG. 1C. That is, in the switching element 1, in a normal state, the first electrode 11 and the second electrode 12 are connected through a fusible conductor 13 (FIG. 1C). If the heat of the high-melting-point metal body 15 is used to melt the fusible conductor 13, The conduction between the first electrode 11 and the second electrode 12 is blocked (FIG. 2C).

Then, the switching element 1 is used by being incorporated in, for example, the alarm circuit 30. FIG. 4 is a diagram showing an example of a circuit configuration of the alarm circuit 30. The alarm circuit 30 includes a drive circuit 33 and a control circuit 34. This drive circuit 33 activates the alarm 31 using a first fuse 35 composed of the fusible conductor 13 of the switching element 1. The control circuit 34 includes a functional circuit 32 that is formed separately from the drive circuit 33. In the functional circuit 32, a second fuse 36 composed of a high-melting-point metal body 15 having a melting point higher than the melting point of the fusible conductor 13 is connected in series with a power source.

As shown in FIG. 4, in the switching element 1, the first fuse 35 (fusible conductor 13) The two external connection terminals 11a and 12a are connected to an alarm device 31 such as an indicator lamp. The alarm device 31 is energized during normal times and is interrupted when an abnormality occurs. In the switching element 1, the two external connection terminals 15 a of the second fuse 36 (high-melting-point metal body 15) are connected to the functional circuit 32.

In the switching element 1 having such a configuration, the fusible conductor 13 is melted by the heat generated by the high-melting-point metal body 15 adjacent to the first electrode 11 and the second electrode 12 of the activation alarm 31 to block the first Current is applied between the electrode 11 and the second electrode 12. That is, in the switching element 1, the high-melting-point metal body 15 is physically and electrically independent from the first electrode 11 and the second electrode 12, and has the ability to melt the fusible conductor 13 by using the heat generated by the high-melting-point metal body 15. On the other hand, the power is interrupted (so-called thermal connection).

Therefore, the switching element 1 can be constructed without using mechanical elements such as springs and alarm contacts, and without using physical linkage of the mechanical elements. Therefore, the switching element 1 can be designed in a small size within the surface of the insulating substrate 10, and the size of the switching element 1 can be reduced. Switching element 1 can also be installed in the mounting area. Moreover, since the number of parts and the number of processes of the switching element 1 are reduced, cost reduction can be achieved. Furthermore, since the insulating substrate and the like can be surface-mounted using reflow soldering, the switching element 1 can be easily mounted even in a miniaturized mounting area.

Since the high-melting-point metal body 15 and the first electrode 11 and the second electrode 12 are physically and electrically separated from each other, the switching element 1 is, for example, a power system power line in which the high-melting-point metal body 15 serving as a fuse is disposed. When an alarm signal is issued from a separate signal system line, the influence of power supply noise when the high-melting-point metal body 15 is fused can be suppressed. Therefore, since a circuit for suppressing noise is not required, a highly reliable alarm circuit can be configured.

In actual use, the switching element 1 causes a high-melting-point metal body 15 to flow in excess of a rated current due to a failure of the functional circuit 32. Therefore, as shown in Figure 2A, if The high-melting-point metal body 15 generates heat and transmits heat to the fusible conductor 13 through the insulating substrate 10 and the front ends 11 b and 12 b of the first electrode 11 and the second electrode 12, so that the fusible conductor 13 is melted. The fused conductor of the fusible conductor 13 is aggregated on the front ends 11 b and 12 b of the first electrode 11 and the second electrode 12 heated by the high-melting-point metal body 15. Therefore, in the switching element 1, since the energization between the first electrode 11 and the second electrode 12 is blocked, the energization to the alarm 31 of the drive circuit 33 can be stopped (FIG. 2C). The alarm circuit 30 can notify an abnormality by stopping the power to the alarm 31, for example, by turning off an indicator lamp or the like.

At this time, in the switching element 1, since the heat-generating portion 15b that is partially thinly formed is provided near the fusible conductor 13 in the high-melting-point metal body 15, the high-resistance heat-generating portion 15b becomes high temperature. By effectively melting the fusible conductor 13, it is possible to quickly short-circuit the first electrode 11 and the second electrode 12. Moreover, in the high-melting-point metal body 15, only the high-resistance heating portion 15b becomes locally high, so in addition to the heat dissipation effect, the two external connection terminals 15a facing the sides can be kept at a relatively low temperature. Therefore, in the switching element 1, it is difficult to melt the mounting solder on the external connection terminal 15a.

As shown in FIG. 3A to FIG. 3C, after the current between the first electrode 11 and the second electrode 12 is interrupted, the high-melting-point metal body 15 also continues to generate heat, so the high-melting-point metal body 15 is thermally fused by its own Joule. (Figures 3A and 3B). Therefore, in the switching element 1, since the power supply from the functional circuit 32 to the high-melting-point metal body 15 is blocked, the heat generation is stopped (FIG. 3C). At this time, since the high-melting-point metal body 15 is covered with the insulating layer 16 in the switching element 1, arc discharge can be suppressed, and therefore, the explosive scattering of the molten conductor can be suppressed. In addition, since the partially-heated portion 15b is provided on the high-melting-point metal body 15, the melting point is reduced, so that the flying amount of the molten conductor can be reduced.

As described above, in the switching element 1, since the high-melting metal body 15 having a melting point higher than the melting point of the fusible conductor 13 generates heat, the fusible conductor 13 can be reliably melted before the high-melting metal body 15. The energization of the first electrode 11 and the second electrode 12 is interrupted. That is, in the switching element 1, the melting of the high-melting-point metal body 15 is not a condition for blocking the energization between the first electrode 11 and the second electrode 12. Accordingly, the switching element 1 can be used as an alarm element that transmits information that an abnormally high-melting-point metal body 15 accompanying the functional circuit 32 flows into an overcurrent exceeding a rated current. Therefore, according to the alarm circuit 30 equipped with the switching element 1, the operation of the alarm device 31 such as the extinguishing indicator lamp can detect the abnormality of the functional circuit 32 as early as possible, and prevent the functional circuit 32 from stopping before the functional circuit 32 completely fails, so that Take measures such as starting a backup circuit.

In addition, the high-melting-point metal body 15 automatically stops heat generation by its Joule thermal fusion. Therefore, since the switching element 1 does not need to be provided with a mechanism for restricting power supply by the functional circuit 32, it is possible to stop the heat generation of the high-melting-point metal body 15 with a simple configuration, and it is possible to miniaturize the entire element.

In the switching element 1, an electrode of the first electrode 11 and the second electrode 12 that is close to the heat-generating portion 15 b of the high-melting metal body 15 may be connected to the high-melting metal body 15. As shown in FIGS. 5A to 5C, in the switching element 1, when the heating portion 15 b of the high-melting-point metal body 15 is close to the front end portion 11 b of the first electrode 11, the high-melting-point metal body 15 and the first One electrode 11 is connected to the connection portion 19. The connection portion 19 is patterned using, for example, the same conductive material as the high-melting metal body 15 or the first electrode 11 and the same process as the high-melting metal body 15 or the first electrode 11.

By connecting the high-melting-point metal body 15 to the first electrode 11, in the switching element 1, if the high-melting-point metal body 15 generates heat at the time of energization, it passes through the connection portion 19 and the first electrode. 11 can also transfer heat to the fusible conductor 13, so the fusible conductor 13 can be melted faster. Therefore, the connection portion 19 is preferably formed of a metal material such as Ag or Cu having excellent thermal conductivity.

The connection portion 19 is provided at a position slightly apart from the center of the heat generating portion 15 b of the high-melting-point metal body 15. When the connection portion 19 is provided, the resistance value is easily reduced and the temperature is hardly increased. Therefore, in order that the heat generating portion 15b can generate heat and generate high temperature, and the high-melting-point metal body 15 is fused by self-heating, it is necessary to provide the connecting portion 19 at a position away from the center of the heat generating portion 15b.

[Cover member]

In the switching element 1, a cover member 20 that protects the inside of the switching element 1 is mounted on the insulating substrate 10. In the switching element 1, the cover member 20 covers the insulating substrate 10 to protect the inside of the switching element 1. The cover member 20 has a side wall 21 constituting a side surface of the switching element 1 and a top surface portion 22 constituting an upper surface of the switching element 1, and is connected to the insulating substrate 10 through the side wall 21 to form a cover plate that closes the inside of the switching element 1. The cover member 20 is formed using, for example, an insulating material such as a thermoplastic, a ceramic, or a glass epoxy substrate.

As shown in FIG. 6, in the cover member 20, a cover electrode 23 may be formed on the inner surface side of the top surface portion 22. The cover electrode 23 is formed at a position overlapping one of the first electrode 11 and the second electrode 12. The cover electrode 23 is more preferably close to the heat generating portion 15 b of the refractory metal body 15 and overlaps the front end portion 11 b of the first electrode 11 formed in a relatively large area. This is because if the fusible conductor 13 is melted due to the heat generated by the high-melting-point metal body 15, the fused conductor condensed on the end portion 11b before the first electrode 11 contacts the cover electrode 23 and diffuses and wets, thereby making it possible to hold the fused conductor. Since the amount of reception is increased, the use of the cover electrode 23 can more reliably block the current between the first electrode 11 and the second electrode 12.

[Modification 1]

Further, in a switching element to which this technology is applied, a high-melting-point metal body and the first electrode or the second electrode may be overlapped on the surface of the insulating substrate. In the following description, the same constituent elements as those of the switching element 1 described above are assigned the same reference numerals, and detailed descriptions of the constituent elements are omitted. In the switching element 40, as shown in FIGS. 7A and 7B, a high-melting-point metal body 15 is formed so as to extend between mutually opposing sides 10d, 10e in the surface 10a of the insulating substrate 10. Moreover, in the switching element 40, the first electrode 11 and the second electrode 12 are respectively formed along the opposite sides 10b, 10c of the surface 10a of the insulating substrate 10.

The high-melting-point metal body 15 is covered with a first insulating layer 41 in a substantially central portion of the insulating substrate 10. The high-melting-point metal body 15 has external connection terminals 15 a formed on the sides 10 d and 10 e of the insulating substrate 10, respectively. The high-melting-point metal body 15 is formed so that the middle portion is thinner than both end portions, thereby forming a heat generating portion 15 b that generates heat and generates high temperature.

The first electrode 11 has an external connection terminal 11 a formed on a side 10 b of the insulating substrate 10, and the second electrode 12 has an external connection terminal 12 a formed on a side 10 c of the insulating substrate 10. The first electrode 11 is formed from the side 10b to the first insulating layer 41, and the second electrode 12 is formed from the side 10c to the first insulating layer 41. Since the front end portions 11b and 12b are close to and spaced from each other on the first insulating layer 41, the first electrode 11 and the second electrode 12 are spaced apart. In addition, the first electrode 11 and the second electrode 12 are covered with a second insulating layer 42 except for the tip portions 11b and 12b.

Connection solders are provided on the front ends 11b and 12b of the first electrodes 11 and the second electrodes 12, and the fusible conductors 13 are connected to the front ends 11b and 12b using the connection solders. also, In the switching element 40, as shown in FIG. 7A and FIG. 7B, either of the first electrode 11 and the second electrode 12, the front end portion 11b of the first electrode 11 formed in a relatively large area is connected to the front end portion. A part of the fusible conductor 13 of 11 b overlaps with the heat generating portion 15 b of the refractory metal body 15. In addition, the fusible conductor 13 is coated with a flux 18 in order to prevent oxidation, improve wettability, and the like.

As a forming material of each of the first insulating layer 41 and the second insulating layer 42, an insulating material containing glass or the like, which is the same as the insulating layer 16 of the switching element 1 described above, is preferable.

According to the switching element 40, since most of the front end portion 11b and the fusible conductor 13 of the first electrode 11 are arranged so as to overlap with the heat generating portion 15b of the refractory metal body 15, the heat generating portion 15b is used. The heat quickly melts the fusible conductor 13 to block the current between the first electrode 11 and the second electrode 12. At this time, in the switching element 40, since the heat generating portion 15b is continuously laminated with the first electrode 11 and the fusible conductor 13 through the first insulating layer 41 containing glass or the like, the heat generated in the heat generating portion 15b can be efficiently Transfer to fusible conductor 13.

[Modification 2]

Moreover, in the switching element to which this technology is applied, since the first and second electrodes are formed on the surface of the insulating substrate and the high-melting-point metal body is formed on the back surface of the insulating substrate, the high-melting-point metal body and the first The first electrode 11 or the second electrode 12 overlap each other. In the following description, the same constituent elements as those of the switching element 1 described above are assigned the same reference numerals, and detailed descriptions of the constituent elements are omitted. In the switching element 50, as shown in FIGS. 8A and 8B, a refractory metal body 15 is formed between the opposite sides 10 d and 10 e of the back surface 10 f of the insulating substrate 10. In the switching element 50, the first electrode 11 and the second electrode 12 are formed on the opposite sides 10b, 10c of the surface 10a of the insulating substrate 10, respectively.

The high-melting-point metal body 15 is covered with a first insulating layer 51 in a substantially central portion of the insulating substrate 10. The high-melting-point metal body 15 has external connection terminals 15 a formed on the sides 10 d and 10 e of the insulating substrate 10, respectively. The high-melting-point metal body 15 is formed such that a middle portion overlapping the first electrode 11 or the second electrode 12 is thinner than both end portions, thereby forming a heat generating portion 15 b that generates heat and generates a high temperature.

The first electrode 11 has an external connection terminal 11 a formed on a side 10 b of the insulating substrate 10, and the second electrode 12 has an external connection terminal 12 a formed on a side 10 c of the insulating substrate 10. The first electrode 11 is formed at a substantially central portion from the side 10b to the surface 10a of the insulating substrate 10, and the second electrode 12 is formed at a substantially central portion from the side 10c to the surface 10a of the insulating substrate 10. In the substantially central portion of the surface 10 a of the insulating substrate 10, the front ends 11 b and 12 b are close to and spaced apart from each other, so the first electrode 11 and the second electrode 12 are spaced apart. In addition, the first electrode 11 and the second electrode 12 are covered with a second insulating layer 52 except for the tip portions 11b and 12b.

Connection solders are provided on the front ends 11b and 12b of the first electrodes 11 and the second electrodes 12, and the fusible conductors 13 are connected to the front ends 11b and 12b using the connection solders. In the switching element 50, as shown in FIG. 8A and FIG. 8B, either of the first electrode 11 and the second electrode 12, the front end portion 11b of the first electrode 11 formed in a relatively large area is connected to the front end. A part of the fusible conductor 13 of the portion 11 b overlaps with the heat generating portion 15 b of the refractory metal body 15. In addition, the fusible conductor 13 is coated with a flux 18 in order to prevent oxidation, improve wettability, and the like.

As a forming material of each of the first insulating layer 51 and the second insulating layer 52, an insulating material containing glass or the like, which is the same as the insulating layer 16 of the switching element 1 described above, is preferable.

According to the switching element 50 in this manner, most of the front end portion 11 b and the fusible conductor 13 of the first electrode 11 are arranged so as to overlap the heating portion 15 b of the refractory metal body 15. Therefore, by melting the fusible conductor 13 faster by the heat generated by the heat generating portion 15b, it is possible to block the current between the first electrode 11 and the second electrode 12. At this time, in the switching element 50, as the insulating substrate 10, a ceramic substrate or the like having excellent thermal conductivity is used, as in the case where the high-melting-point metal body 15 is formed on the same surface as the surface on which the fusible conductor 13 is provided. , Can heat the fusible conductor 13.

[Modification of fusible conductor]

As described above, any or all of the fusible conductors 13 may contain a low melting point metal and a high melting point metal. The high-melting-point metal layer 60 is formed of a material containing at least one of Ag and Cu as a constituent element, and the material may be an alloy. The low-melting-point metal layer 61 contains solder or lead-free solder containing Sn as a main component. At this time, as the fusible conductor 13, as shown in FIG. 9A, a fusible conductor including a high-melting metal layer 60 as an inner layer and a low-melting metal layer 61 as an outer layer may be used. In this case, the fusible conductor 13 may have a structure in which the entire surface of the high-melting-point metal layer 60 is covered with the low-melting-point metal layer 61, or may have a structure in which the high-melting-point metal layer 60 is low except for a pair of side surfaces facing each other. Structure in which the melting point metal layer 61 is covered. The structure covered with the high-melting-point metal layer 60 or the low-melting-point metal layer 61 can be formed using a known film-forming technique such as electroplating.

As shown in FIG. 9B, as the fusible conductor 13, a fusible conductor including a low-melting metal layer 61 as an inner layer and a high-melting metal layer 60 as an outer layer may be used. In this case, the fusible conductor 13 may have a structure in which the entire surface of the low-melting-point metal layer 61 is covered with the high-melting-point metal layer 60, or may have a structure in which the low-melting-point metal layer 61 is covered in addition to a pair of side surfaces facing each other. Structure covered with the high-melting-point metal layer 60.

As shown in FIGS. 10A and 10B, the fusible conductor 13 may have a laminated structure in which a high-melting metal layer 60 and a low-melting metal layer 61 are laminated.

Specifically, as shown in FIG. 10A, the fusible conductor 13 may include A lower layer supported by the first electrode 11 and the second electrode 12 and a two-layer structure formed by laminating the upper layer on the lower layer. In this case, the upper-area layer of the high-melting-point metal layer 60 as the lower layer may be used as the upper-low-melting metal layer 61, and the upper-area layer of the lower-melting metal layer 61 as the lower layer may be used as the upper-melting metal layer 60. . Alternatively, as shown in FIG. 10B, the fusible conductor 13 may be formed in a three-layer structure including an inner layer and two outer layers laminated on top and bottom of the inner layer. In this case, two low-melting metal layers 61 as the outer layer may be laminated on the upper and lower surfaces of the high-melting metal layer 60 as the inner layer, and may be laminated on the upper and lower surfaces of the low-melting metal layer 61 as the inner layer. Two high-melting-point metal layers 60 as outer layers.

Further, as shown in FIG. 11, the fusible conductor 13 may have a multilayer structure of four or more layers in which a high-melting metal layer 60 and a low-melting metal layer 61 are alternately laminated. In this case, the fusible conductor 13 may have a structure in which the entire surface or a metal layer other than the outermost layer except for a pair of side surfaces facing each other is covered with the outermost metal layer.

Further, the fusible conductor 13 may have a structure in which the high-melting-point metal layer 60 is laminated on the surface of the low-melting-point metal layer 61 as an inner layer in a striped manner. 12A and 12B are top views of the fusible conductor 13.

In the fusible conductor 13 shown in FIG. 12A, on the surface of the low-melting-point metal layer 61, a plurality of linear high-melting-point metal layers arranged in a width direction and arranged in a predetermined interval and extending in a length direction are formed. 60, a linear opening portion 62 can be formed along the longitudinal direction, and the low-melting-point metal layer 61 is exposed in the opening portion 62. In the fusible conductor 13, if the low-melting-point metal layer 61 is exposed at the opening 62, the contact area between the molten low-melting-point metal and the high-melting-point metal increases, and the erosion effect of the high-melting-point metal layer 60 is further promoted. The fusing property of the fusible conductor 13 is improved. The opening 62 is formed on the low-melting-point metal layer 61, for example, and has a high melting point. The metal of the metal layer 60 is formed by partial plating.

Further, as shown in FIG. 12B, the fusible conductor 13 may be formed on the surface of the low-melting-point metal layer 61 by forming a plurality of linear shapes arranged at predetermined intervals in the longitudinal direction and extending in the width direction. The high-melting-point metal layer 60 has linear openings 62 formed along the width direction.

In the fusible conductor 13, as shown in FIG. 13, a high-melting metal layer 60 is formed on the surface of the low-melting metal layer 61, and a circular opening is formed on the entire surface of the high-melting metal layer 60. The portion 63 may expose the low-melting-point metal layer 61 in the opening portion 63. The opening 63 is formed, for example, on the low-melting-point metal layer 61 by performing partial plating of the metal constituting the high-melting-point metal layer 60.

In the fusible conductor 13, if the low-melting-point metal layer 61 is exposed at the opening 63, the contact area of the molten low-melting-point metal and the high-melting-point metal increases, and the erosion effect of the high-melting-point metal is further promoted, so that The fusing property of the fused conductor 13.

Further, in the fusible conductor 13, as shown in FIG. 14, a plurality of openings 64 are formed in the high-melting-point metal layer 60 as an inner layer, and the high-melting-point metal layer 60 is made low by using a plating technique or the like. The melting point metal layer 61 is formed into a film, and the low melting point metal layer 61 may be filled in the opening portion 64. Therefore, in the fusible conductor 13, since the contact area between the molten low melting point metal and the high melting point metal is increased, the low melting point metal can attack the high melting point metal in a shorter time.

In the fusible conductor 13, it is preferable that the volume of the low-melting metal layer 61 be larger than the volume of the high-melting metal layer 60. In the fusible conductor 13, since the fusible conductor 13 is heated by the high-melting-point metal body 15, the low-melting metal of the fusible conductor 13 is eroded while melting the high-melting metal, so the fusible conductor 13 can be quickly melted. And fusing. Therefore, in the fusible conductor 13, By making the volume of the low-melting-point metal layer 61 larger than the volume of the high-melting-point metal layer 60, it is possible to promote this erosion effect and quickly interrupt the current flow between the first and second electrodes 11 and 12.

This application claims priority based on Japanese Patent Application No. 2014-008133 filed with the Japan Patent Office on January 20, 2014, and is incorporated herein by reference in its entirety.

All modifications, combinations, sub-combinations, and changes made by those skilled in this case based on design requirements and other factors should be covered by the scope of additional patent applications and their equivalents.

The present technology can also adopt the following configurations.

(1)

A switching element includes: a fusible conductor; a first electrode connected to one end portion of the fusible conductor; a second electrode connected to the other end portion of the fusible conductor; and a high-melting-point metal body having a ratio The fusible conductor has a high melting point.

(2)

The switching element according to the above (1), wherein the fusible conductor is melted by heat generated with an overcurrent exceeding a rated current flowing into the refractory metal body.

(3)

The switching element according to the above (1) or (2), wherein the high-melting-point metal body interrupts energization between the first electrode and the second electrode, and then uses an overcurrent associated with a rated current or more. The current self-heats and blows.

(4)

The switching element according to any one of (1) to (3), wherein the high-melting-point metal body, the first electrode, and the second electrode are each an electrode pattern formed on an insulating substrate.

(5)

The switching element described in the above (4), wherein the refractory metal body, the first electrode, and the second electrode are patterned refractory metals, respectively, and the refractory metal contains at least silver (Ag ) And copper (Cu) as its constituent elements.

(6)

The switching element described in the above (4) or (5), wherein the high-melting-point metal body as the electrode pattern includes a heat-generating portion that locally generates heat due to current concentration, and the heat-generating portion is the high-melting point A portion of the metal body that is partially tapered at a position close to the fusible conductor.

(7)

The switching element described in the above (6), wherein the front end portion of the first electrode connected to the fusible conductor and the front end portion of the second electrode connected to the fusible conductor Close to the heating part.

(8)

The switching element described in (7) above, wherein The area ratio between the front end portion of the first electrode connected to the fusible conductor and the front end portion of the second electrode connected to the fusible conductor. The area of the other front end portion is large, and the electrode having the one front end portion holds more of the fusible conductor than the electrode having the other front end portion.

(9)

The switching element according to the above (7) or (8), in the first electrode and the second electrode, one electrode having a front end portion close to the heat generating portion and the high melting point Metal body connection.

(10)

The switching element according to any one of the above (1) to (9), wherein the high-melting-point metal body is covered with an insulating layer.

(11)

The switching element according to any one of the above (4) to (10), wherein an insulating layer is formed between the high-melting-point metal body and the insulating substrate.

(12)

The switching element according to any one of the above (1) to (11), wherein the first electrode and the second electrode are each covered with an insulating layer except for a portion to which the fusible conductor is connected. .

(13)

The switching element according to any one of the above (10) to (12), wherein the insulating layer contains an insulating material, The insulating material contains glass.

(14)

The switching element according to any one of the above (1) to (3), wherein the refractory metal body is a foil containing at least one of copper and silver as a constituent element thereof, or a foil containing at least copper and silver One of the filaments as its constituent element.

(15)

The switching element according to any one of (4) to (14), wherein the first electrode and the second electrode and the refractory metal body are arranged in parallel on a same plane of the insulating substrate .

(16)

The switching element according to any one of the above (4) to (8), wherein one of the first electrode and the second electrode is connected to the first electrode and the second electrode on one surface of the insulating substrate. The fusible conductor of one of the electrodes is laminated on the refractory metal body via an insulating layer.

(17)

The switching element according to any one of the above (4) to (8), wherein the first electrode and the second electrode are arranged on one surface of the insulating substrate; and on the insulating substrate On the other side, the refractory metal body is disposed; one of the refractory metal body and the first electrode and the second electrode, and the fusible conductor connected to the one electrode. Overlap each other.

(18)

The switching element described in the above (16) or (17), wherein An insulating layer is formed between the metal body and the insulating substrate.

(19)

The switching element according to any one of the above (16) to (18), wherein the first electrode and the second electrode are respectively insulated by the insulation except a portion where the fusible conductor is connected. Layer covered.

(20)

The switching element according to any one of the above (16) to (19), wherein the insulating layer contains an insulating material, and the insulating material contains glass.

(twenty one)

The switching element according to any one of the above (4) to (20), wherein the insulating substrate is a ceramic substrate.

(twenty two)

The switching element according to any one of the above (1) to (21), wherein the fusible conductor contains solder.

(twenty three)

The switching element according to any one of the above (1) to (21), wherein the fusible conductor contains a low melting point metal and a high melting point metal; the low melting point metal is melted by heat generation of the high melting point metal body At the same time, the high melting point metal is eroded.

(twenty four)

The switching element described in the above (23), wherein The low melting point metal contains solder, and the high melting point metal contains at least one of silver and copper as a constituent element thereof.

(25)

The switching element according to the above (23) or (24), wherein the fusible conductor has a coating structure including a high melting point metal layer as an inner layer and a low melting point metal layer as an outer layer.

(26)

The switching element according to the above (23) or (24), wherein the fusible conductor has a coating structure including a low-melting metal layer as an inner layer and a high-melting metal layer as an outer layer.

(27)

The switching element according to the above (23) or (24), wherein the fusible conductor has a laminated structure in which a low melting point metal layer and a high melting point metal layer are laminated.

(28)

The switching element according to the above (23) or (24), wherein the fusible conductor has a multilayer structure of four or more layers in which a low-melting metal layer and a high-melting metal layer are alternately laminated.

(29)

The switching element according to the above (23) or (24), wherein the fusible conductor has a laminated structure in which a high-melting-point metal layer as an outer layer is laminated on a surface of a low-melting-point metal layer as an inner layer. An opening is provided in the high-melting-point metal layer.

(30)

The switching element according to the above (23) or (24), wherein the fusible conductor includes a refractory metal layer having a plurality of openings, and The low melting point metal layer on the high melting point metal layer is filled with the low melting point metal layer in the opening portion.

(31)

The switching element according to any one of the above (23) to (30), in the fusible conductor, a volume of a low-melting metal is larger than a volume of a high-melting metal.

(32)

The switching element according to any one of (1) to (31) above, wherein the fusible conductor is coated with a flux.

(33)

The switching element according to any one of the above (1) to (32), wherein a surface of each of the first electrode and the second electrode is plated with nickel (Ni) / gold (Au), and nickel / palladium (Pd) Either plating or Ni / Pd / Au plating.

(34)

The switching element according to any one of the above (4) to (33), further comprising a cover member provided on the insulating substrate, and the cover member and the first electrode and the first A cover electrode is provided at a position where either of the two electrodes overlaps.

(35)

A switching circuit includes a switching unit including a first electrode and a second electrode connected to each other through a first fuse and to an external circuit, and interrupting a gap between the first electrode and the second electrode. Power on to stop power supply to the external circuit; The second fuse has a melting point higher than the melting point of the first fuse, and is connected to a functional circuit that is electrically independent from the switch unit.

(36)

The switching circuit according to the above (35), wherein the first fuse is fused and the first fuse is interrupted by using heat generated by an overcurrent exceeding a rated current flowing into the second fuse. The power supply between the electrode and the second electrode stops power supply to the external circuit.

(37)

In the switch circuit according to the above (35) or (36), after the second fuse is blown, the second fuse is blown by self-heating with an overcurrent exceeding a rated current.

(38)

An alarm circuit including a driving circuit including a first electrode and a second electrode connected to each other through a first fuse, and stopping an alarm by blocking the power supply between the first electrode and the second electrode. The second fuse is electrically independent from the driving circuit and has a higher melting point than the first fuse. The control circuit has a functional circuit in which the second fuse is connected in series to a power source.

(39)

The alarm circuit according to the above (38), wherein the first fuse is fused by utilizing heat generated with an overcurrent that exceeds a rated current flowing into the second fuse when the functional circuit is abnormal. 2. Interrupting power supply between the first electrode and the second electrode, and stopping power supply to the alarm device.

(40)

The alarm circuit according to the above (38) or (39), wherein the second fuse is blown by self-heating with an overcurrent exceeding a rated current after the first fuse is blown.

Claims (40)

A switching element includes: a fusible conductor; a first electrode connected to one end portion of the fusible conductor; a second electrode connected to the other end portion of the fusible conductor; and a high-melting-point metal body having a ratio The fusible conductor has a high melting point. The switching element according to claim 1, wherein the fusible conductor is melted by heat generated as a result of an overcurrent exceeding a rated current flowing into the refractory metal body. The switching element according to item 1 of the scope of patent application, wherein the high-melting-point metal body interrupts energization between the first electrode and the second electrode, and then uses Self-heating and fusing. The switching element according to claim 1, wherein the high-melting-point metal body, the first electrode, and the second electrode are electrode patterns formed on an insulating substrate, respectively. The switching element according to item 4 of the scope of patent application, wherein the high-melting-point metal body, the first electrode, and the second electrode are each a patterned high-melting metal, and the high-melting metal includes at least silver One of (Ag) and copper (Cu) is used as its constituent element. The switching element according to item 4 of the scope of patent application, wherein the high-melting-point metal body as the electrode pattern includes a heat-generating portion that locally generates heat due to current concentration, and the heating portion is the high-melting-point metal body. A portion that is partially tapered at a position close to the fusible conductor. The switching element according to item 6 of the scope of patent application, wherein a front end portion of the first electrode connected to the fusible conductor and a front end portion of the second electrode connected to the fusible conductor Either one is close to the heat generating portion. The switching element according to item 7 of the scope of patent application, wherein the front end portion of the first electrode connected to the fusible conductor and the front end portion of the second electrode connected to the fusible conductor The area of the front end of one side which is close to the heating portion is larger than the area of the other front end, and the electrode having the front end of the one side holds more of the available electrodes than the electrode having the front end of the other side. Fused conductor. The switching element according to item 7 of the scope of patent application, wherein, among the first electrode and the second electrode, one electrode having a front end portion close to the heat generating portion and the refractory metal body connection. The switching element according to claim 1, wherein the high-melting-point metal body is covered with an insulating layer. The switching element according to item 4 of the scope of patent application, wherein an insulating layer is formed between the high-melting-point metal body and the insulating substrate. The switching element according to item 1 of the scope of patent application, wherein the first electrode and the second electrode are respectively covered with an insulating layer except for a portion to which the fusible conductor is connected. The switching element according to claim 10, wherein the insulating layer includes an insulating material, and the insulating material includes glass. The switching element according to item 1 of the scope of patent application, wherein the refractory metal body is a foil containing at least one of copper and silver as its constituent element, or a foil containing at least one of copper and silver as its constituent element. Element of silk. The switching element according to item 4 of the scope of patent application, wherein the first electrode and the second electrode are arranged in parallel with the refractory metal body on the same plane of the insulating substrate. The switching element according to item 4 of the scope of patent application, wherein on one of the surfaces of the insulating substrate, one of the first electrode and the second electrode is connected to the electrode connected to the one of the electrodes. A fusible conductor is laminated on the refractory metal body via an insulating layer. The switching element according to item 4 of the scope of patent application, wherein the first electrode and the second electrode are arranged on one surface of the insulating substrate; and on the other surface of the insulating substrate The high-melting-point metal body is arranged; the high-melting-point metal body overlaps one of the first electrode and the second electrode, and the fusible conductor connected to the one electrode. The switching element according to item 16 of the scope of patent application, wherein an insulating layer is formed between the high-melting-point metal body and the insulating substrate. The switching element according to item 16 of the scope of patent application, wherein the first electrode and the second electrode are respectively covered with the insulating layer except for a portion to which the fusible conductor is connected. The switching element according to claim 16 in which the insulating layer includes an insulating material, and the insulating material includes glass. The switching element according to item 4 of the scope of patent application, wherein the insulating substrate is a ceramic substrate. The switching element according to claim 1, wherein the fusible conductor includes solder. The switching element according to item 1 of the scope of patent application, wherein the fusible conductor contains a low melting point metal and a high melting point metal; the low melting point metal is melted by the heat of the high melting point metal body and simultaneously dissolves the high melting point metal. The switching element according to claim 23, wherein the low-melting-point metal includes solder, and the high-melting-point metal includes at least one of silver and copper as a constituent element thereof. The switching element according to claim 23, wherein the fusible conductor has a coating structure including a high melting point metal layer as an inner layer and a low melting point metal layer as an outer layer. The switching element according to claim 23, wherein the fusible conductor has a coating structure including a low-melting metal layer as an inner layer and a high-melting metal layer as an outer layer. The switching element according to claim 23, wherein the fusible conductor has a laminated structure in which a low-melting-point metal layer and a high-melting-point metal layer are laminated. The switching element according to item 23 of the scope of application, wherein the fusible conductor has a multilayer structure of four or more layers in which a low-melting metal layer and a high-melting metal layer are alternately laminated. The switching element according to item 23 of the scope of patent application, wherein the fusible conductor has a laminated structure in which a high-melting-point metal layer as an outer layer is laminated on a surface of a low-melting-point metal layer as an inner layer. The layer is provided with an opening. The switching element according to claim 23, wherein the fusible conductor includes a high melting point metal layer having a plurality of openings, and a low melting point metal layer formed on the high melting point metal layer. The opening is filled with the low-melting-point metal layer. The switching element according to item 23 of the scope of patent application, wherein in the fusible conductor, the volume of the low-melting metal is larger than that of the high-melting metal. The switching element according to claim 1, wherein the fusible conductor is coated with a flux. The switching element according to item 1 of the scope of patent application, wherein the surfaces of each of the first electrode and the second electrode are nickel (Ni) / gold (Au) plating, Ni / palladium (Pd) plating, and Ni Either / Pd / Au plating is applied. The switching element according to claim 4 includes a cover member provided on the insulating substrate, and the cover member and any one of the first electrode and the second electrode are provided. At the overlapping position, a cover electrode is provided. A switching circuit includes a switching unit including a first electrode and a second electrode that are connected to each other through a first fuse and are connected to an external circuit, and interrupts between the first electrode and the second electrode. The energization stops the power supply to the external circuit. The second fuse has a melting point higher than the melting point of the first fuse, and is connected to a functional circuit that is electrically independent from the switch unit. The switching circuit according to claim 35, wherein the first fuse is fused by using heat generated by an overcurrent exceeding a rated current flowing into the second fuse, thereby blocking the first fuse. The power supply between the first electrode and the second electrode stops power supply to the external circuit. The switching circuit according to claim 35, wherein after the second fuse is blown, the second fuse is blown by self-heating with an overcurrent exceeding a rated current. An alarm circuit including a driving circuit including a first electrode and a second electrode connected to each other through a first fuse, and stopping an alarm by blocking power to the first electrode and the second electrode. The second fuse is electrically independent from the driving circuit and has a higher melting point than the first fuse. The control circuit has a functional circuit in which the second fuse is connected in series to a power source. The alarm circuit according to item 38 of the scope of patent application, wherein the first fuse is made by using heat generated when an overcurrent exceeding the rated current flowing into the second fuse is generated when the functional circuit is abnormal. The filament melts, interrupts the current flow between the first electrode and the second electrode, and stops power supply to the alarm device. The alarm circuit according to claim 38, wherein after the second fuse is blown, the second fuse is blown by self-heating with an overcurrent exceeding a rated current.