TWI681433B - Protection device and battery pack - Google Patents

Abstract

Provided is a protection device that includes: an insulating substrate; a plurality of heat generators provided on the insulating substrate; a heat generator extraction electrode electrically connected to each of the heat generators; and a fusible conductor supported by the heat generator extraction electrode.

Description

Protection components and battery pack

The present invention relates to a protection element for protecting a circuit connected to the current path by blocking the current path, and a battery pack using the protection element.

Because it can be charged, most secondary batteries that can be used repeatedly are provided to users in a state of being processed into a battery pack. In particular, when a lithium ion secondary battery with a high weight energy density is used, in order to ensure the safety of users and electronic equipment, in general, in view of overcharge protection, overdischarge protection, etc., a plurality of protection circuits are built in Battery. Therefore, the battery pack has a function of blocking output under a predetermined situation.

Many electronic devices using lithium-ion secondary batteries perform over-charge protection or over-discharge protection operations on the battery pack by using the ON/OF output of the FET switch built into the battery pack. However, even in the case where the FET switch is short-circuited and damaged for some reason, or when a momentary large current flows due to the application of a lightning surge, etc., or the output voltage is abnormally low due to the life of the battery cell, otherwise the output is too large In the case of abnormal voltage, the battery pack and electronic equipment must be protected from fire and other accidents. For this reason, even in any abnormal state so conceivable, in order to safely block the output of the battery cell, the A protection element composed of a fuse element that should block the function of the current path from an external signal.

As a protective element mounted in such a protective circuit for a lithium ion secondary battery or the like, as described in Patent Documents 1 and 2, a heating element is provided, and the heat generated by the heating element is used to fuse a meltable conductor introduced into a current path Protection elements are used.

[Prior Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2010-3665

[Patent Document 2] Japanese Unexamined Patent Publication No. 2014-32769

However, in order to use protection elements for applications with relatively low current capacity, such as mobile phones and notebook computers, fusible conductors (fuses) also have a maximum current capacity of only about 15A. Since the use of lithium ion secondary batteries is expanding in recent years, the use of lithium ion secondary batteries has been considered for use in larger currents, and the use of lithium ion secondary batteries has begun to be adopted in some applications. The application of this large current is, for example, electric tools such as electric screwdrivers, transportation equipment such as hybrid vehicles, electric vehicles, and electric auxiliary bicycles. In the use of these large currents, especially at the time of start-up, large currents such as over 10A to 100A may flow. It is desirable to have a protection element corresponding to such a large current capacity.

Therefore, even in the case where a large-sized fusible conductor is used to cope with a large current, it is desirable to provide a protection capable of achieving a stable heat-generating operation by maintaining fast fusing performance without reducing power density, and mitigating thermal shock to an insulating substrate Components and battery packs.

In order to solve the above-mentioned problems, a protection element of an embodiment of the present invention includes: an insulating substrate; a plurality of heating elements disposed on the insulating substrate; and a heating element extraction electrode (heat generator extraction electrode), which is respectively The heating element is electrically connected; and the fusible conductor is supported by the electrode led by the heating element.

In addition, a battery pack according to an embodiment of the present invention includes: one or more battery cells; a protection element connected to the one or more battery cells so as to block current flowing through the one or more battery cells; and Current control elements, which respectively detect the voltage values of the one or more battery cells and control the current for heating the protection element. The protection element includes: an insulating substrate; a plurality of heating elements arranged on the insulating substrate; heating element extraction electrodes, which are respectively electrically connected to the plurality of heating elements; and a fusible conductor, which leads the electrodes from the heating element support.

According to the protection element and the battery pack according to an embodiment of the present invention, the heating element extraction electrodes are electrically connected to the plurality of heating elements, respectively, and the fusible conductor is supported by the heating element extraction electrodes. In this case, since the heating element is divided into plural numbers, the heat shock equivalent to the case where the heating element is not divided into plural numbers is maintained, and the thermal shock to the insulating substrate due to heat generation is alleviated. That is, since the heating element is divided into plural numbers, the peak of diffusion in the heat distribution of the insulating substrate decreases, so the thermal shock to the insulating substrate is alleviated. On the other hand, because even if the heating element is divided, the same total heating value can be maintained, the time required for fusing the fusible conductor will not be prolonged. Therefore, even when the size of the fusible conductor is increased and the power of the heating element is increased in order to cope with a large current capacity, it is possible to suppress the breakage of the insulating substrate and realize a stable heating operation.

1‧‧‧Protection element

2‧‧‧Insulation substrate

3‧‧‧Heating body

4‧‧‧Electrode leading electrode

5‧‧‧ Fusible conductor

7‧‧‧ connection material

10‧‧‧Outer frame

11‧‧‧1st electrode

12‧‧‧ 2nd electrode

13‧‧‧Insulation

15‧‧‧First heating element electrode

16‧‧‧Second heating element electrode

17‧‧‧Heating body connected to electrode

20‧‧‧Through hole

30‧‧‧ battery pack

31~34‧‧‧Battery unit

35‧‧‧ battery stack

36‧‧‧ detection circuit

37‧‧‧current control element

40‧‧‧Charge and discharge control circuit

41, 42‧‧‧ current control element

43‧‧‧Control Department

45‧‧‧Charging device

50‧‧‧Protection element

51‧‧‧ Suction hole

52‧‧‧conductive layer

53‧‧‧Back electrode

55‧‧‧Preparation of solder

FIG. 1 is a cross-sectional view showing a protection element according to an embodiment of the present invention.

Fig. 2 is a plan view showing a protection element according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a protective element in which a fusible conductor is fused by self-heating accompanying an overcurrent.

4 is a cross-sectional view of a protective element in which a fusible conductor is fused by heat generated by a heating element.

5 is a cross-sectional view showing another protection element according to an embodiment of the present invention.

6 is a cross-sectional view showing another protection element according to an embodiment of the present invention.

7 is a cross-sectional view showing another protection element according to an embodiment of the present invention.

8 is a diagram showing an example of a circuit configuration of a battery pack to which a protection element according to an embodiment of the present invention is applied.

9 is a circuit diagram showing a protection element according to an embodiment of the present invention.

FIG. 10 is a cross-sectional view of a protection element provided with an attraction hole in an insulating substrate.

Fig. 11 is a plan view showing a protection element provided with an attraction hole in an insulating substrate.

FIG. 12 is a cross-sectional view of a protection element provided with an attraction hole in an insulating substrate, and shows a state after the fusible conductor is fused.

13 is a plan view showing a protection element of a comparative example.

14 is a cross-sectional view of a protection element of a reference example.

Fig. 15 is a plan view showing a protection element of a reference example.

The protective element to which an embodiment of the present invention is applied is described below with reference to the drawings Detailed description. In addition, the present invention is not limited to the following embodiments, and of course various changes can be made without departing from the gist of the present invention. In addition, because the drawings are schematic diagrams, the ratio of each dimension may differ from the actual ratio. The specific dimensions should be considered and judged according to the following description. In addition, of course, there may be cases where the relationship and ratio of mutual dimensions are different.

[First embodiment]

As shown in FIGS. 1 and 2, a protective element 1 according to an embodiment of the present invention includes an insulating substrate 2, a plurality of heating elements 3 disposed on the insulating substrate 2, and each of the plurality of heating elements 3 The connected heating element extraction electrode 4 and the fusible conductor 5 supported by the heating element extraction electrode 4. In addition, the protective element 1 includes a first electrode 11 and a second electrode 12, and the insulating substrate 2 is disposed between the first electrode 11 and the second electrode 12. In the protection element 1, one end of the fusible conductor 5 is disposed on the first electrode 11, the one end is electrically connected to the first electrode 11, and the other end of the fusible conductor 5 is disposed on the second electrode 12 , The other end is electrically connected to the second electrode 12.

[1st electrode and 2nd electrode]

The first electrode 11 and the second electrode 12 are connection terminals for connecting the protection element 1 to an external circuit, and contain metal or the like. Inside the protective element 1, the first electrode 11 and the second electrode 12 are each connected to the soluble conductor 5 through a connection material 7 such as solder, and are also connected to each other through the soluble conductor 5. Therefore, in the protection element 1, a current path is formed from the first electrode 11 to the second electrode 12 via the soluble conductor 5. The current path is connected to the connection terminal of the external circuit through the first electrode 11 and the second electrode 12 and is mounted as a part in the external circuit. Thus, in the protection element 1 In the meantime, if an overcurrent exceeding the rated current flows in the fusible conductor 5, the fusible conductor 5 melts by self-heating. Therefore, as shown in FIG. 3, the fusible conductor 5 is melted between the fusible conductor 5 and one of the first electrode 11 and the second electrode 12, so the charge/discharge path of the external circuit is blocked. Alternatively, in the protection element 1, when the heating element 3 is energized, the heating element 3 generates heat. Therefore, as shown in FIG. 4, because the fusible conductor 5 is melted, the fusible conductor 5 is fused between the first electrode 11 and the heating element extraction electrode 4 and between the second electrode 12 and the heating element extraction electrode 4 The molten conductor 5 is fused. Therefore, since the molten conductor 5a which is the melt of the fusible conductor 5 aggregates on the heating element extraction electrode 4, the current path of the external circuit is blocked.

In the protection element 1, the first electrode 11 and the second electrode 12 are led out from the inside of the outer casing 10 to the outside, and are supported by the outer casing 10. In addition, in the protection element 1, since the insulating substrate 2 is disposed in the central space inside the outer casing 10, the first electrode 11 and the second electrode 12 are close to the insulating substrate 2.

The outer housing 10 contains, for example, any one or more types of engineering plastics excellent in heat resistance such as PPS (polyphenylene sulfide). In addition, when the outer housing 10 is formed into a predetermined shape, it may be formed integrally with the first electrode 11 and the second electrode 12 using insert molding or the like.

In addition, the first electrode 11 and the second electrode 12 may be disposed on an insulating material close to the insulating substrate 2. The insulating material includes, for example, epoxy resin. In addition, as shown in FIG. 5, the first electrode 11 and the second electrode 12 may be formed by applying a high-melting-point metal paste using a printing method or the like to form a pair of opposed edge portions on the surface 2 a of the insulating substrate 2.

[Insulating substrate]

The insulating substrate 2 includes, for example, any one or two or more types of insulating materials such as alumina, glass ceramics, mullite, and zirconia. In addition, although materials used for printed wiring boards such as glass epoxy substrates and phenol substrates may be used, it is necessary to pay attention to the temperature when the fuse is blown.

[heating stuff]

The heating element 3 is arranged on the surface 2 a of the insulating substrate 2 and is covered by the insulating member 13. The heating element 3 includes any one or two or more types of conductive materials that have a relatively high resistance value and generate heat when energized. The conductive material is, for example, W, Mo, Ru, an alloy having these one or more as main components, a composition having these one or more as main components, and a compound having these one or more as main components. Using a screen printing technique, a paste containing a mixture of powders of these alloys and a resin binder, etc. is applied to the insulating substrate 2 in a manner to form a predetermined pattern, and then the paste is calcined to generate heat. Body 3.

In the protection element 1, a plurality of heating elements 3 are spaced apart and juxtaposed at predetermined intervals, for example, as shown in FIG. 1, two heating elements 3A, 3B are provided. In this manner, in the protection element 1, the heating element 3 is divided into plural numbers, thereby maintaining the same amount of heat generation as in the case where the heating element 3 is not divided into plural numbers, and alleviating the thermal shock to the insulating substrate 2 due to heat generation. That is, in the protection element 1, since the heating element 3 is divided into plurals, the peak of diffusion in the heat distribution of the insulating substrate 2 decreases, so the thermal shock to the insulating substrate 2 is alleviated. On the other hand, in the protective element 1, even if the heating element 3 is divided, the same total heating value of the heating element 3 can be maintained, so the time required for the fusible conductor 5 to be fused is not prolonged. Therefore, in the protection element 1, even when the fusible conductor 5 is enlarged in accordance with a large current capacity and the power of the heating element 3 is increased, the insulation substrate 2 can be suppressed from cracking and stable heat generation can be achieved operating.

As shown in FIG. 2, the fusible conductor 5 extends from the first electrode 11 toward the second electrode 12. The heating elements 3A and 3B each have a rectangular planar shape with the direction crossing (for example, orthogonal) the extending direction of the soluble conductor 5 as the longitudinal direction. One end of each of the heating elements 3A and 3B in the longitudinal direction is connected to the first heating element electrode 15 disposed on the surface 2a of the insulating substrate 2 through the heating element connection electrode 17a, and the heating elements 3A and 3B in the longitudinal direction are each The other end portion is connected to the second heating element electrode 16 disposed on the surface 2a of the insulating substrate 2 through the heating element connection electrode 17b.

The first heating element electrode 15 is connected to one end of each of the plurality of heating elements 3 and is connected to the heating element extraction electrode 4. The second heating element electrode 16 is connected to the other end of each of the plurality of heating elements 3 and becomes an external connection electrode when the protection element 1 is connected to an external circuit. The protective element 1 is connected to an external circuit through the second heating element electrode 16 and is mounted on a power supply path formed in the external circuit to supply power to the heating element 3.

The first heating element electrode 15 and the second heating element electrode 16 contain, for example, any one kind or two or more kinds of refractory metals. The refractory metal is, for example, Ag, Cu, or an alloy containing one or more of these as main components. Using a screen printing technique, a paste containing a mixture of the high melting point metal and a resin binder is applied to the insulating substrate 2 in a manner to form a predetermined pattern, and then the first heating element is formed by firing the paste, etc. The electrode 15 and the second heating element electrode 16.

The heating element 3 generates heat by energizing the first heating element electrode 15 and the second heating element electrode 16. That is, the heating element 3 is energized in the longitudinal direction. Therefore, even when the heating element 3 is broken along the longitudinal direction, since the conduction path between the first heating element electrode 15 and the second heating element electrode 16 is not easily blocked, the energization to the heating element 3 and the heating element 3 fever is not easy to stop. On the other hand, as shown in FIG. 15 described later, because of the width perpendicular to the longitudinal direction The heating element 3 is provided on both sides of the heating element 3 in the direction, so when the heating element 3 generates heat by being energized in the width direction, if the heating element 3 is broken along the longitudinal direction, the first heating element Since the current path between the electrode 15 and the second heating element electrode 16 is easily blocked, the heating of the heating element 3 may stop before the fusible conductor 5 is fused.

The insulating member 13 contains glass, for example. In addition, in the protection element 1, in order to efficiently transfer the heat generated by the heating element 3 to the fusible conductor 5, an insulating member may also be provided between the plurality of heating elements 3 and the insulating substrate 2 The heating element 3 is provided inside the insulating member 13 on the surface 2a of the insulating substrate 2.

[Extraction electrode of heating element]

The heating element extraction electrode 4 supports the fusible conductor 5 connected to the first electrode 11 and the second electrode 12, and constitutes a power supply path to the heating element 3. The heating element extraction electrode 4 has: an extraction portion 4 a adjacent to the first heating element electrode 15; and a connection portion 4 b which is arranged on the insulating member 13 and connected to the soluble conductor 5. In the heating element extraction electrode 4, the connection portion 4 b is disposed between the first electrode 11 and the second electrode 12, and is connected to the first electrode 11 and the second electrode 12 through the soluble conductor 5. Furthermore, the heating element extraction electrode 4 is heated by the heating element 3, and by transferring the heat generated by the heating element 3 to the soluble conductor 5, the soluble conductor 5 is fused. Furthermore, if the fusible conductor 5 melts, the melt of the fusible conductor 5 (melted conductor 5a) agglomerates and the first electrode 11 and the second electrode 12 are cut off, so the heating element extraction electrode 4 blocks the first The current path between the first electrode 11 and the second electrode 12. At this time, since the heating element extraction electrode 4 is heated by the heating element 3, the molten conductor 5a is easily aggregated.

In the heating element lead-out electrode 4, the connection portion 4b passes through the insulating member 13 respectively It is arranged so as to partially overlap with the plurality of heating elements 3. Therefore, since the heat generated by each heating element 3 is easily transmitted to the heating element extraction electrode 4 through the insulating member 13, the heating element extraction electrode 4 can quickly heat the soluble conductor 5 and can quickly melt the soluble conductor 5 . That is, in the protection element 1, if each of the plurality of heating elements 3 generates heat, the heat generated by the plurality of heating elements 3 is transmitted through the insulating member 13 and the heating element extraction electrode 4 disposed on the insulating member 13 To the fusible conductor 5, so the fusible conductor 5 is heated. At this time, in the protection element 1, since the heating element extraction electrodes 4 are arranged so as to partially overlap the divided heating elements 3, the heat generated by the heating elements 3 can be efficiently transferred to the heating element extraction electrodes 4, and the fusible conductor 5 is quickly fused. In addition, in the protection element 1, since the heat generated by the heating element 3 is more easily transferred to the heating element extraction electrode 4 and the fusible conductor 5, the thermal shock to the insulating substrate 2 can be reduced, and the insulating substrate 2 and the heating element 3 Not easy to break.

In addition, as shown in FIG. 1, the heating element extraction electrode 4 may partially overlap both of the heating elements 3A and 3B, or may only partially overlap one of the heating elements 3A and 3B. In view of the thermal conduction to the fusible conductor 5 and the effect of mitigating the thermal shock to the insulating substrate 2, it is preferable that the heating element extraction electrode 4 partially overlap both of the heating elements 3A and 3B.

The heating element extraction electrode 4 contains, for example, any one kind or two or more kinds of refractory metals. The high-melting-point metal is, for example, Ag, Cu, and alloys containing these as main components. Using a screen printing technique, a paste containing a mixture of the high-melting-point metal and a resin binder is applied to the insulating member 13 and the first heating element electrode 15 in a predetermined pattern, and then the paste is applied The heating element extraction electrode 4 is formed by firing or the like.

Then, the heating element extraction electrode 4 is connected to the soluble conductor 5 connected to the first electrode 11 and the second electrode 12 through a connecting material 7 such as solder. Also, if the electrode 4 When the hot fusible conductor 5 is melted, the molten conductor 5a aggregates, so that the current path between the first electrode 11 and the second electrode 12 is blocked.

In addition, in the protection element 1, as shown in FIG. 1, it is preferable to use the center of the insulating substrate 2 as a boundary, the heating elements 3A and 3B are arranged on both sides of the boundary, and the heating element extraction electrode 4 is arranged on the insulation The center of the substrate 2 and the surrounding area. In the insulating substrate 2, the closer to the outer edge portion, the higher the cooling effect due to heat radiation, and the heat in the central portion farthest from the outer edge portion tends not to be easily radiated. For this reason, in the central portion of the insulating substrate 2, since the stress due to thermal expansion becomes large, the insulating substrate 2 is easily broken. Therefore, in the insulating substrate 2, if the heating elements 3A and 3B are arranged in a region avoiding the central portion, the heat generated by the heating elements 3A and 3B is accumulated in the central portion of the insulating substrate 2, so even if it is caused by In the case of stress due to thermal expansion or cracking of the insulating substrate 2, the effect of the cracking does not easily affect the heating elements 3A and 3B.

In addition, if the heating element extraction electrode 4 is disposed in the center of the insulating substrate 2 and its surrounding area, in the protection element 1, the heat generated by the heating elements 3A, 3B is concentrated in the central portion of the insulating substrate 2 that is not easily radiated. This heat is not distributed to the entire insulating substrate 2 but is efficiently transferred to the fusible conductor 5. Therefore, the fusible conductor 5 is effectively heated. At the same time, in the protection element 1, if the heat generated by the heating elements 3A, 3B is concentrated in the central portion of the insulating substrate 2, the heat is transmitted to the soluble conductor 5 through the heating element extraction electrode 4. For this reason, since the heat generated by the heating elements 3A and 3B tends not to be easily dissipated and accumulated in the central portion of the insulating substrate 2 whose stress increases due to thermal expansion, the insulating substrate 2 is less likely to break.

Furthermore, the second heating element electrode 16 is arranged on the other end side of each of the plurality of heating elements 3 so as to face the plurality of heating elements 3 respectively, and the insulating substrate 2 is in a region where the heating element 3 is not arranged. Use a bonding material such as solder to connect to an external circuit through the second heating element electrode 16 The terminal part. For this reason, in the protective element 1, because the insulating substrate 2 is fixed in the area where the heating element 3 is not provided, the insulating substrate 2 generates stress in the area where the heating element 3 is not provided because the heating element 3 generates heat. Therefore, even if the insulating substrate 2 is cracked, the occurrence position of the crack can be controlled in a region where the heating element 3 is not arranged. In particular, if the two heating elements 3A and 3B are placed on the center of the insulating substrate 2 as a boundary and are arranged on both sides of the boundary, the heat generated in the heating elements 3A and 3B is concentrated on the central portion of the insulating substrate 2 that is not easily radiated In addition, in the case of stress accumulation accompanying thermal expansion, since the second heating element electrode 16 becomes a fixed point, the occurrence position of the crack can be accurately controlled in the area between the heating elements 3A and 3B. Therefore, even in the case where the insulating substrate 2 is broken, it is possible to prevent occurrence of a situation in which heat generation stops due to the breakage of the heating elements 3A, 3B.

Here, as shown in FIGS. 1 and 2, the through hole 20 (conductive through hole) provided with the conductive layer 61 on the inner wall surface of the insulating substrate 2 may also be provided on the back surface 2 b of the insulating substrate 2 The connecting terminal portion 62 electrically connected to the second heating element electrode 16 through the conductive layer 61 connects and fixes the second heating element electrode 16 to the terminal portion of the external circuit through the connecting terminal portion 62. In the protection element 1, by providing a through hole 20 at a fixed point of the insulating substrate 2, the insulating substrate 2 is easily broken with the through hole 20 as a starting point. Therefore, it is possible to prevent occurrence of a situation in which heat generation stops due to the rupture of the heating elements 3A and 3B. In addition, after FIG. 3, illustration of the conductive layer 61 and the connection terminal portion 62 is omitted.

In addition, the second heating element electrode 16 may be connected and fixed to the terminal portion of the external circuit by a solder bridge disposed from the front surface 2a to the rear surface 2b of the insulating substrate 2. In this case, in the protective element 1, since the insulating substrate 2 is fixed in the area where the heating element 3 is not provided, the occurrence position of the crack can also be controlled in the area where the heating element 3 is not provided.

[Fusable conductor]

The fusible conductor 5 melts in an overcurrent state. The fusible conductor 5 contains any one kind or two or more kinds of conductive materials that can be fused. The conductive material is, for example, SnAgCu-based lead-free solder, BiPbSn alloy, BiPb alloy, BiSn alloy, SnPb alloy, PbIn alloy, ZnAl alloy, InSn alloy, and PbAgSn alloy. In addition, the fusible conductor 5 may be a laminate of a high-melting-point metal such as Ag, Cu, and an alloy containing one or more of these as a main component, a solder, or a low-melting-point metal such as a lead-free solder containing Sn as a main component.

In this way, the fusible conductor 5 is formed by forming a high-melting-point metal layer on a low-melting-point metal foil using an electroplating technique. However, the fusible conductor 5 can also be formed using other known lamination techniques and film formation techniques. In addition, the soluble conductor 5 may have a high-melting-point metal layer as an inner layer and a low-melting-point metal layer as an outer layer. In addition, the fusible conductor 5 may have a multilayer structure in which four or more low-melting-point metal layers and high-melting-point metal layers are alternately stacked. In this way, the fusible conductor 5 can be formed in various configurations.

In addition, the fusible conductor 5 does not generate heat due to the fact that a predetermined rated current flows, and therefore does not melt. On the other hand, the fusible conductor 5 melts because it self-heats when a current higher than the rated current flows. Therefore, the current path between the first electrode 11 and the second electrode 12 is blocked. In addition, when the fusible conductor 5 generates heat in response to the energization of the heating element 3, it is melted because it is heated by the heating element 3. Therefore, the current path between the first electrode 11 and the second electrode 12 is blocked. At this time, in the fusible conductor 5, since the molten low-melting-point metal corrodes the high-melting-point metal, the high-melting-point metal melts at a temperature lower than the melting temperature. Therefore, the fusible conductor 5 is fused in a short time by utilizing the erosion effect of the low melting point metal on the high melting point metal.

In addition, in the fusible conductor 5, the high-melting-point metal that becomes the outer layer is laminated to form It is a low-melting-point metal in the inner layer, and its fusing temperature is significantly lower than that of chip fuses made of high-melting-point metal. Therefore, in the fusible conductor 5, the fuse area becomes larger than that of chip fuses of the same size and the like, and the current rating is greatly improved. In addition, compared with chip fuses of the same current rating, it is possible to achieve miniaturization, thinning, and excellent fast blowability.

Furthermore, in the fusible conductor 5, a phenomenon in which an abnormally high voltage is instantaneously applied to the circuit on which the protection element 1 is mounted, that is, the so-called surge resistance (pulse resistance) is improved. That is, the fusible conductor 5 cannot be fused if, for example, a current of 100 A flows for a few msec. In this regard, a large current flowing in a very short time flows through the surface layer of the conductor (skin effect). Since the fusible conductor 5 includes a high melting point metal such as Ag plating having a low resistance value as an outer layer, a current applied due to a surge wave easily flows, and therefore, it is possible to prevent the fusible conductor 5 from melting due to self-heating. Therefore, in the fusible conductor 5, since the low-melting-point metal is coated with the high-melting-point metal, the resistance to surges is greatly improved compared to a fuse made of a solder alloy.

In addition, in the fusible conductor 5, in order to prevent oxidation, improve wettability at the time of fusing, etc., a flux (not shown) is applied.

[heating stuff]

In addition, as shown in FIG. 6, in the protection element 1, the heating element 3 may be disposed on the back surface 2 b of the insulating substrate 2. The heating element 3 is disposed on the back surface 2b of the insulating substrate 2 and is covered with an insulating member 13 on the back surface 2b.

One end of the heating element 3 is electrically connected to the heating element extraction electrode 4 and the fusible conductor 5 disposed on the heating element extraction electrode 4 through an unillustrated heating element electrode. In addition, the other end of the heating element 3 is connected to the second heating element electrode 16.

In addition, as shown in FIG. 7, in the protection element 1, the heating element 3 may be disposed inside the insulating substrate 2. In this case, the heating element 3 may not be covered with an insulating layer such as glass. In addition, one end of the heating element 3 is electrically connected to the heating element extraction electrode 4 and the fusible conductor 5 disposed on the heating element extraction electrode 4 through an unillustrated heating element electrode. In addition, the other end of the heating element 3 is connected to the second heating element electrode 16.

[Circuit configuration]

For example, if the protective element 1 is mounted on a battery pack, the fusible conductor 5 itself will be fused when an overcurrent flows, so the charging and discharging path of the battery pack is blocked. In addition, if the protection element 1 is energized and generates heat in response to the overvoltage of the battery cell, the fusible conductor 5 heated by the heating element 3 is fused, so the charge/discharge path of the battery pack is blocked.

As shown in FIG. 8, the battery pack 30 includes, for example, a battery stack 35 composed of battery cells 31 to 34 of a total of four lithium ion secondary batteries.

The battery pack 30 includes a battery stack 35, a charge and discharge control circuit 40 that controls the charging and discharging of the battery stack 35, a protection element 1 (the protection element of the present invention is applied) that stops the charging operation when the battery stack 35 is abnormal, and detects each battery cell The voltage detection circuit 36 of 31 to 34 and the current control element 37 of the switching element that controls the operation of the protection element 1 based on the detection result of the detection circuit 36.

In the battery stack 35, battery cells 31 to 34 that need to be controlled for overcharge protection and overdischarge protection are connected in series. The battery stack 35 is detachably connected to the charging device 45 through the positive terminal 30 a and the negative terminal 30 b of the battery pack 30, and a charging voltage is applied from the charging device 45. The battery pack 30 charged by the charging device 45 passes through the positive terminal 30a and the negative terminal 30b is connected to an electronic device driven by a battery, and can drive the electronic device.

The charge and discharge control circuit 40 includes two current control elements 41 and 42 connected in series with the current path from the battery stack 35 to the charging device 45, and a control unit 43 that controls the operations of the current control elements 41 and 42. The current control elements 41 and 42 include, for example, field effect transistors (hereinafter referred to as FETs). Since the gate voltage is controlled by the control unit 43, the state (on and off) of the current path of the battery stack 35 can be controlled. The control section 43 receives power supply from the charging device 45 to operate, and according to the detection result of the detection circuit 36, when the battery stack 35 is in an over-discharge state or an over-charge state, controls the operation of the current control elements 41, 42 to block the current path .

The protection element 1 is introduced into the charge and discharge current path between the battery stack 35 and the charge and discharge control circuit 40, for example, and the operation of the protection element 1 is controlled by the current control element 37.

The detection circuit 36 is connected to each of the battery cells 31 to 34 and supplies each voltage value detected by the battery cells 31 to 34 to the control unit 43 of the charge and discharge control circuit 40. In addition, the detection circuit 36 outputs a control signal for controlling the current control element 37 when any of the battery cells 31 to 34 is in an overcharge voltage state or an overdischarge voltage state.

The current control element 37 includes, for example, an FET. The current control element 37 drives the protection element 1 when the voltage value of the battery cells 31 to 34 exceeds a predetermined overdischarge state or overcharge state based on the detection signal output from the detection circuit 36. Therefore, the charging and discharging current path of the battery stack 35 is blocked without relying on the switching operation of the current control elements 41, 42.

The protection element 1 of the present invention is applied to the battery pack 30 having the above configuration, and has the circuit configuration shown in FIG. 9. That is, in the protection element 1, the first electrode 11 is connected to the battery stack 35 side, and the second electrode 12 is connected to the positive terminal 30a side. Therefore, the fusible conductor 5 is introduced into the charging and discharging path of the battery stack 35 in series. Also, in the protection element 1, The heating element 3 is connected to the current control element 37 through the second heating element electrode 16, and the heating element 3 is connected to the open end of the battery stack 35. Therefore, one end of the heating element 3 is connected to one of the open ends of the battery stack 35 through the heating element extraction electrode 4, the soluble conductor 5 and the first electrode 11. The other end of the heating element 3 is connected to the other open end of the current control element 37 and the battery stack 35 through the second heating element electrode 16. Therefore, a power supply path to the heating element 3 is formed, and the energization of the heating element 3 is controlled by the current control element 37.

[Operation of protection element]

If an overcurrent exceeding the rated current flows in the battery pack 30, in the protective element 1, the fusible conductor 5 itself generates heat and melts, so the charging and discharging path of the battery pack 30 is blocked.

In addition, if the detection circuit 36 detects an abnormal voltage in any one of the battery cells 31 to 34, it outputs an interruption signal to the current control element 37. The current control element 37 controls the current based on the blocking signal to energize the heating element 3. In the protection element 1, since current flows from the battery stack 35 to the heating element 3 via the first electrode 11, the soluble conductor 5 and the heating element extraction electrode 4, the heating element 3 starts to generate heat. Therefore, in the protective element 1, if the fusible conductor 5 is heated by the heating element 3, the fusible conductor 5 is fused, and the charging and discharging path of the battery stack 35 is blocked (FIG. 3 ).

At this time, when the fusible conductor 5 of the heating element 3 at the time of overvoltage is blown, in the protection element 1, since the heating element 3 is divided into plural numbers, the heat generation equivalent to the case where the heating element 3 is not divided into plural numbers is maintained At the same time, the thermal shock to the insulating substrate 2 due to heat generation is alleviated. Therefore, in the protection element 1, even in the case where the fusible conductor 5 is enlarged in accordance with a large current capacity and the power of the heating element 3 is increased, the fusible conductor 5 can be used The time required for the fusing is not prolonged, and the insulating substrate 2 is not easily broken, so that a stable heating operation is achieved.

In addition, in the protection element 1, the heating element extraction electrode 4 is arranged in such a manner as to partially overlap the plurality of heating elements 3 through the insulating member 13 because the heat generated by each heating element 3 is effectively transmitted to the insulating member 13 to The fusible conductor 5 can quickly heat and melt the fusible conductor 5. In addition, in the protection element 1, the heat generated by the heating element 3 is more easily transferred to the heating element extraction electrode 4 and the soluble conductor 5. Therefore, since the thermal shock to the insulating substrate 2 is relaxed, the insulating substrate 2 and the heating element 3 are less likely to break.

In addition, in the protective element 1, since the fusible conductor 5 contains the high-melting-point metal and the low-melting-point metal, the molten low-melting-point metal's corrosive effect on the high-melting-point metal can melt the fusible conductor 5 in a short time.

In addition, in the protective element 1, since the fusible conductor 5 is fused and the power supply path to the heating element 3 is blocked, the heating of the heating element 3 is stopped.

The protection element according to an embodiment of the present invention is not limited to the case of a battery pack equipped with a lithium ion secondary battery, but can of course also be applied to various applications in which it is necessary to block a current path according to an electrical signal.

[Second Embodiment]

In addition, in the protection element to which one embodiment of the present invention is applied, as shown in FIG. 10, the heating conductor lead electrode 4, the insulating member 13, and the insulating substrate 2 may be provided to attract the soluble conductor 5 The molten material melts the suction hole 51 of the conductor 5a. In addition, in the following description, the same components as those of the protection element 1 described above are denoted by the same reference numerals, and detailed descriptions of the same components are omitted.

In the protective element 50 provided with the suction hole 51, if the fusible conductor 5 is melted by self-heating accompanied by overcurrent or the fusible conductor 5 is melted by heat generated by the heating element 3 due to overvoltage, the capillary phenomenon is used Since the molten conductor 5a is attracted to the inside of the suction hole 51, the volume of the molten conductor 5a is reduced. In the protective element 50, even when the cross-sectional area of the fusible conductor 5 is increased to respond to a large current application and the amount of melting is increased, the molten conductor 5a is attracted by the suction hole 51, so that the The volume of the molten conductor 5a is reduced.

Therefore, in the protective element 50, the fusible conductor 5 is quickly and reliably fused. In addition, in the protective element 50, even if an arc discharge occurs when the self-heating of the fusible conductor 5 accompanied by an overcurrent occurs, the scattering of the molten conductor 5a caused by the arc discharge can be reduced. Therefore, it is possible to prevent the insulation resistance from decreasing, and it is possible to prevent a short-circuit failure caused by the melted conductor 5 a adhering to the surrounding circuit of the meltable conductor 5.

A conductive layer 52 is provided on the inner wall surface of the suction hole 51. By providing the conductive layer 52, the suction hole 51 becomes easy to attract the molten conductor 5a. The conductive layer 52 contains, for example, any one kind or two or more kinds of conductive materials. The conductive material is, for example, copper, silver, gold, iron, nickel, palladium, lead, tin, alloys containing these as main components, and the like. A conductive material (conductive paste) is formed on the inner wall surface of the suction hole 51 by a known method such as electrolytic plating method or printing method to form a conductive layer 52.

In addition, the suction hole 51 is preferably a through-hole extending in the thickness direction of the insulating substrate 2. Therefore, in the suction hole 51, the molten conductor 5 a is attracted to the back surface 2 b of the insulating substrate 2. Thus, since more molten conductors 5a are attracted, the volume of the molten conductors 5a is further reduced where the fusible conductors 5 melt. In addition, the suction hole 51 may be a non-through hole.

In addition, as shown in FIG. 11, the insulating member 13 is transmitted through the surface 2 a of the insulating substrate 2 The heating element extraction electrode 4 is arranged, and the suction hole 51 is arranged at a position corresponding to the central position in the width direction of the heating element extraction electrode 4. In addition, the number of suction holes 51 may be plural. Since the path for attracting the molten conductor 5a is increased, more molten conductor 5a is attracted by the suction hole 51. Therefore, where the fusible conductor 5 melts, the volume of the molten conductor 5a is further reduced. Here, the plurality of suction holes 51 are arranged, for example, linearly, that is, in a row.

In addition, the conductive layer 52 provided on the inner wall surface of the suction hole 51 is connected to the heating element extraction electrode 4. The surface of the conductive layer 52 and the surface of the heating element extraction electrode 4 are preferably in the same plane. The conductive layer 52 and the heating element extraction electrode 4 may be integrated. Therefore, in the protective element 50, the molten conductor 5a aggregated on the heating element extraction electrode 4 becomes easily wetted and diffused on the surface of the heating element extraction electrode 4 and the surface of the conductive layer 52, and the molten conductor 5a penetrates the conductive layer 52 is easily guided into the suction hole 51.

In addition, a back electrode 53 is arranged on the back surface 2b of the insulating substrate 2 so as to be connected to the conductive layer 52 provided on the inner wall surface of the suction hole 51. As shown in FIG. 12, the back electrode 53 is connected to the conductive layer 52. The surface of the back electrode 53 and the surface of the conductive layer 52 are preferably in the same plane. The back electrode 53 and the conductive layer 52 may be integrated. Therefore, when the fusible conductor 5 is melted, the molten conductor 5 a that moves from the front surface 2 a of the insulating substrate 2 to the back surface 2 b through the suction hole 51 aggregates on the back surface electrode 53. Therefore, in the protective element 50, the molten conductor 5a becomes easily wetted and diffused on the surface of the back electrode 53 and the surface of the conductive layer 52. In addition, since more molten conductors 5a are attracted by the suction holes 51, the volume of the molten conductors 5a is further reduced where the fusible conductors 5 melt.

In addition, in the protection element 50, the heating element 3 may be disposed on the front surface 2a, the back surface 2b of the insulating substrate 2, or inside the insulating substrate 2.

When the heating element 3 is disposed on the back surface 2 b of the insulating substrate 2, one end of the heating element 3 is connected to the back electrode 53, and is electrically connected to the soluble conductor 5 through the conductive layer 52 and the heating element extraction electrode 4. In addition, the other end of the heating element 3 is connected to the second heating element electrode 16 disposed on the back surface 2b. Similarly, when the heating element 3 is disposed inside the insulating substrate 2, one end of the heating element 3 is electrically connected to the soluble conductor 5 through the first heating element electrode 15 and the heating element extraction electrode 4, and the heating element 3 The other end is connected to the second heating element electrode 16.

If the heating element 3 is disposed on the back surface 2b of the insulating substrate 2, in the protective element 50, since the back electrode 53 is heated by the heating element 3, more molten conductors 5a are likely to aggregate. Therefore, in the protective element 50, the molten conductor 5a easily moves from the heating element extraction electrode 4 through the conductive layer 52 to the back electrode 53, so that the attraction effect to the molten conductor 5a in the suction hole 51 can be promoted. Therefore, the fusible conductor 5 is easily fused.

In addition, if the heating element 3 is disposed inside the insulating substrate 2, in the protective element 50, since the heating element extraction electrode 4 and the back electrode 53 are heated by the heating element 3 through the conductive layer 52, more molten conductors 5a are likely to aggregate . Therefore, in the protective element 50, the molten conductor 5a easily moves from the heating element extraction electrode 4 through the conductive layer 52 to the back electrode 53, so that the attraction effect to the molten conductor 5a in the suction hole 51 can be promoted. Therefore, the fusible conductor 5 is easily fused.

In addition, in the protection element 50, the suction hole 51 may be filled with the same or similar material as the forming material of the fusible conductor 5, a preliminary solder 55 having a lower melting point than the forming material of the fusible conductor 5, or a flux Wait. In the protection element 50, when the heating element 3 generates heat, the temperature of the conductive layer 52 having excellent thermal conductivity, the heating element extraction electrode 4, and the back electrode 53 is higher than the temperature of the insulating substrate 2. Thereby, since the pre-solder 55 is melted before the fusible conductor 5 in equal parts, the molten conductor 5 a is attracted by the suction hole 51. Therefore, because the molten conductor 5a is removed from the surface of the insulating substrate 2 Since the surface 2a moves to the back surface 2b, the current path between the first electrode 11 and the second electrode 12 is easily blocked regardless of the orientation of the protection element 50.

Here, the problems that arise when the protection element according to one embodiment of the present invention described above is not used are as follows.

The protection element 100 as a reference example of the protection element 1 of the present invention includes, as shown in FIGS. 14 and 15, an insulating substrate 103, a first electrode 101 and a second electrode 102, a heating element 104, a glass layer 105, and a heating element The extraction electrode 106, a pair of heating element connection electrodes 107a and 107b, the first heating element electrode 108, the second heating element electrode 109, and the fusible conductor 110. The first electrode 101 and the second electrode 102 are connected to an external circuit. The heating element 104 is disposed on the insulating substrate 103, and contains high melting point metals such as W, Mo, and Ru. The glass layer 105 insulatingly covers the heating element 104. The heating element extraction electrode 106 is arranged on the glass layer 105 so as to overlap with the heating element 104, and is electrically connected to the heating element 104. A pair of heating element connection electrodes 107a and 107b are arranged on the insulating substrate 103, and are connected to both ends of the heating element 104 in the width direction. The first heating element electrode 108 is connected to the heating element 104 through the heating element connection electrode 107a, and is also connected to the heating element extraction electrode 106. The second heating element electrode 109 is connected to the heating element connection electrode 107a, and the heating element 104 is connected to an external power supply circuit. The fusible conductor 110 is connected to the first electrode 101 and the second electrode 102 through the heating element extraction electrode 106. The fusible conductor 110 is connected to the first electrode 101, the second electrode 102, and the heating element extraction electrode 106 through a connection material 111 such as solder. In addition, in FIG. 15, the glass layer 105 is omitted.

In the protection element 100, by connecting the first electrode 101 and the second electrode 102 to an external circuit, the fusible conductor 110 is incorporated into the current path of the external circuit. In addition, in the protection element 100, the second heating element electrode 109 is connected to an external circuit to form The power supply path from the fusible conductor 110, the heating element extraction electrode 106, the heating element 104, and the second heating element electrode 109 to an external circuit, that is, the power supply path to the heating element 104.

Normally, in the protection element 100, a switching element provided in an external circuit restricts the power supply path. Then, in the case where the current path of the external circuit is blocked, in the protection element 100, if the energization restriction on the power supply path is released by the switching element, the heating element 104 is energized while generating heat, and the fusible conductor 110 is fused. Therefore, the current path of the external circuit is blocked, and at the same time, the power supply to the heating element 104 is also stopped.

In order to respond to a large current capacity, in the protection element 100, the cross-sectional area of the fusible conductor 110 is increased to reduce the resistance of the fusible conductor 110. Here, if the cross-sectional area of the fusible conductor 110 is increased to cope with a large current, the power required to fuse the fusible conductor 110 by heat generated by the heating element 104 also increases.

However, in a protective element for a relatively low current capacity, if the fusible conductor 110 is enlarged and a large current flows into the fusible conductor 110, the thermal shock to the insulating substrate 103 becomes too large. The insulating substrate 103 is easily broken where the heating element 104 is arranged. In the insulating substrate 103, the closer to the outer edge portion, the higher the cooling effect due to heat radiation and the highest temperature in the central portion. Therefore, if the heating element 104 is formed in the central portion, the stress accompanying thermal expansion becomes larger. Furthermore, in the protective element 100, the fusible conductor 110 is fixed to the heating element extraction electrode 106 that overlaps the heating element 104 through the glass layer 105, so the stress (deformation) generated in the central portion of the insulating substrate 103 affects Operation of the protection element 100. Specifically, since the central portion of the insulating substrate 103 becomes easily broken, and the heating element 104 formed in the central portion becomes easily broken, there is a possibility that the heating element is stopped due to the interruption of the power supply path. The situation becomes unstable.

In this tendency, the more the fusible conductor 110 is made larger in order to increase the current rating of the protection element 100 and the insulating substrate 103 is made thinner in order to make the protection element 100 smaller, the more prominent it becomes.

In order to mitigate the thermal shock to such an insulating substrate 103, for example, it is also conceivable to reduce the power density by increasing the area of the heating element 104. However, if the power density is reduced, the insulating substrate 103 and the heating element 104 can be prevented from cracking. However, since the heat transfer efficiency to the soluble conductor 110 is reduced, it is difficult to quickly melt the soluble conductor 110.

[Example]

Next, an embodiment of the present invention will be described. In this embodiment, a protective element 1 in which two heating elements 3 are arranged on an insulating substrate 2 and a heating element extraction electrode 4 is partially overlapped with the two heating elements 3 is prepared (Example: Reference FIG. 1); and a protective element 200 in which two heating elements 3 are arranged on the insulating substrate 2 and the heating element extraction electrode 4 is arranged so as not to partially overlap the two heating elements 3 (Comparative example: refer to FIG. 13 ), and the fusing time of the fusible conductor 5 generated by the heating element 3 is measured.

In the protective element 1 of the embodiment and the protective element 200 of the comparative example, as the insulating substrate 2, a ceramic substrate on which two heating elements 3 are arranged on the surface is used. As the fusible conductor 5 connected to the first electrode 11 and the second electrode 12, a Sn-Ag-Cu-based metal foil (thickness 0.35 mm, width 5.4 mm) to which Ag plating (thickness 6 μm) was applied was used. ). The fusible conductor 5 is connected to the first electrode 11 and the second electrode 12 using solder. In addition, the first electrode 11 and the second electrode 12 are supported by the outer frame 10 made of PPS.

By applying power of 32W and 100W to the protection element 1 of the example and the protection element 200 of the comparative example, the fusible conductor 5 was fused by the heat of the heating element 3, and the The melting time of the molten conductor 5. In this case, the number of measurements (number of samples) is set to 4. The measurement results are shown in Table 1.

As shown in Table 1, in the protection element 1 of the example, in the case of any of the applied power system of 32 W and 100 W, the fuse time of the protection element 200 of the comparative example becomes shorter than that of the comparative example. On the other hand, in the protection element 200 of the comparative example, when the power of 100 W was applied, the insulating substrate 2 was broken in half of the samples, so the soluble conductor 5 could not be fused (NG).

This result shows the following tendency. In the embodiment, the heating element extraction electrode 4 is arranged so as to overlap the two heating elements 3. For this reason, because the heat generated by each heating element 3 is easily transmitted to the heating element extraction electrode 4 through the insulating member 13, the fusible conductor 5 is quickly heated and melted. Moreover, in the embodiment, the heat generated by the heating element 3 is more easily transferred to the heating element extraction electrode 4 and the soluble conductor 5. Therefore, even when the power of 100 W is applied, since the thermal shock to the insulating substrate 2 can be relaxed, the insulating substrate 2 and the heating element 3 are less likely to be broken.

On the other hand, in the comparative example, the heating element extraction electrode 4 is arranged so as not to overlap the two heating elements 3. For this reason, because the heat generated by each heating element 3 is difficult to be efficiently transferred to the heating element extraction electrode 4, that is, the conduction efficiency of the heating element 3 to the heating element extraction electrode 4 is low, the fusing time is extended compared to the embodiment. Furthermore, in the comparative example, the heat generated by the heating element 3 is easily accumulated in the insulating substrate 2. Therefore, in the case of applying 100 W of power, because the thermal shock to the insulating substrate 2 becomes excessive, the insulating substrate 2 is broken and the fusible conductor 5 is not fused in half of the samples.

Therefore, the protection element in which a plurality of heating elements are arranged on the insulating substrate and the heating element lead-out electrodes are arranged so as to partially overlap with each heating element is used to quickly melt the fusible conductor and to reduce the thermal shock to the insulating substrate. Ensuring stable heating operation is effective.

This application claims priority based on the Japanese Patent Application 2014-110513 filed with the Japanese Patent Office on May 28, 2014, and is incorporated by reference with reference to the entire contents of the case.

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

1‧‧‧Protection element

2‧‧‧Insulation substrate

2a‧‧‧surface

3A, 3B‧‧‧Heating body

4‧‧‧Electrode leading electrode

5‧‧‧ Fusible conductor

7‧‧‧ connection material

10‧‧‧Outer frame

11‧‧‧1st electrode

12‧‧‧ 2nd electrode

13‧‧‧Insulation

Claims (7)

A protection element comprising: an insulating substrate; a plurality of heating elements arranged on the insulating substrate; a heating generator extraction electrode (heat generator extraction electrode), which is electrically connected to the plurality of heating elements, respectively; and The molten conductor is supported by the heating element extraction electrode; the heating element extraction electrode is arranged so as to partially overlap with the plurality of heating elements, and the plurality of heating elements are bounded by the center of the insulating substrate Is arranged on both sides of the boundary, and the heating element extraction electrode is arranged in a region from the center of the insulating substrate to both sides thereof. A protection element as claimed in item 1 of the patent scope, wherein the fusible conductor extends in a predetermined direction, and each of the plurality of heating elements has a rectangular planar shape, which is A direction in which the extending direction of the molten conductor crosses is a longitudinal direction, and one end of each of the plurality of heating elements in the longitudinal direction is connected to the heating element extraction electrode, and each of the plurality of heating elements in the longitudinal direction The other end is connected to the external connection electrode. A protection element as claimed in item 1 of the patent scope, wherein the fusible conductor extends in a predetermined direction, and one of the plurality of heating elements in a direction crossing the extending direction of the fusible conductor On the side, the external connection electrodes are respectively arranged so as to face the plurality of heating elements, and the insulating substrate is fixed to an external circuit through the external connection electrodes in a region where the plurality of heating elements are not arranged. A protection element as claimed in item 3 of the patent scope, wherein the plurality of heating elements are arranged on the surface of the insulating substrate, and the connection terminal part is arranged on the back surface opposite to the surface of the insulating substrate, The external connection electrode is connected to the connection terminal portion through a conductive through hole provided on the insulating substrate, and the connection terminal portion is connected to the external circuit. A protection element as claimed in item 3 of the patent scope, wherein the plurality of heating elements are arranged on the surface of the insulating substrate, and a solder bridge is arranged from the surface of the insulating substrate to the back surface on the opposite side ), the external connection electrode is connected to the external circuit through the solder bridge. A protection element as claimed in item 1 of the patent application, wherein the insulating substrate has a suction hole in the thickness direction, and the suction hole attracts a molten conductor of the meltable conductor, that is, a molten conductor. A battery pack including: one or more battery cells; a protection element connected to the one or more battery cells in a manner capable of blocking current flowing through the one or more battery cells; and a current control element, which Separately detect the voltage value of the one or more battery cells and control the current for heating the protection element, The protection element includes: an insulating substrate; a plurality of heating elements arranged on the insulating substrate; heating element extraction electrodes, which are electrically connected to the plurality of heating elements, respectively; and a fusible conductor, which is formed by the The heating element extraction electrode is supported; the heating element extraction electrode is arranged so as to partially overlap with the plurality of heating elements, and the plurality of heating elements are arranged on the boundary with the center of the insulating substrate as a boundary On both sides, the heating element extraction electrode is arranged in a region from the center of the insulating substrate to both sides.

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