WO2015107632A1

WO2015107632A1 - Protective element

Info

Publication number: WO2015107632A1
Application number: PCT/JP2014/050524
Authority: WO
Inventors: 千智小森; 幸市向; 古田　和隆; 利顕荒木; 康二江島; 貴史藤畑
Original assignee: デクセリアルズ株式会社
Priority date: 2014-01-15
Filing date: 2014-01-15
Publication date: 2015-07-23

Abstract

In the present invention, the cross section of a fusible conductor is increased to raise the rating of the protective element while maintaining the insulation capability thereof. The protective element is provided with: an insulation substrate (11); a heating body (14) layered over the insulation substrate (11); an insulation member (15) covering the heating body (14); first and second electrodes (12) layered over the insulation substrate (11) whereon the insulation member (15) has been layered; a heating body drawing electrode (16) layered over the insulation member (15) so as to overlap with the heating body (14) and electrically connected to the heating body (14) in a current path between the first and second electrodes (12); and a fusible conductor (13) layered throughout from the heating body drawing electrode (16) to the first and second electrodes (12) and blown out by heat so as to interrupt the current path between the first electrode (12) and the second electrode (12). An in-flow portion (40) where the molten fusible conductor (13) flows into is provided under a blow-out portion (13a) of the fusible conductor (13).

Description

Protective element

The present invention relates to a protection element that stops charging / discharging of a battery connected on the current path by fusing the current path and suppresses thermal runaway of the battery.

Most of the rechargeable batteries that can be charged and used repeatedly are processed into battery packs and provided to users. In particular, in lithium ion secondary batteries with high weight energy density, in order to ensure the safety of users and electronic devices, in general, several protection circuits such as overcharge protection and overdischarge protection are built in the battery pack, It has a function of shutting off the output of the battery pack in a predetermined case.

Some types of protection elements perform overcharge protection or overdischarge protection operation of the battery pack by turning on / off the output using an FET switch built in the battery pack. However, when the FET switch is short-circuited for some reason, when a lightning surge or the like is applied and an instantaneous large current flows, the output voltage drops abnormally due to the life of the battery cell, or conversely an excessively abnormal voltage Even when a battery pack is output, battery packs and electronic devices must be protected from accidents such as fire. Therefore, in order to safely shut off the output of the battery cell in any possible abnormal state, a protection element made of a fuse element having a function of cutting off the current path by an external signal is used. .

As a protection element of a protection circuit for such a lithium ion secondary battery, a soluble conductor is connected across the first and second electrodes on the current path as described in Patent Document 1. Some of the current paths form a part of the current path, and the fusible conductor on the current path is melted by self-heating due to overcurrent or by a heating element provided inside the protective element. In such a protective element, the molten liquid soluble conductor is collected on the first and second electrodes, thereby interrupting the current path.

JP 2010-003665 A

In the protective element using the soluble conductor described above, it is preferable to increase the distance between the first and second electrodes in order to improve the insulation performance when the current path is interrupted. However, along with the downsizing and thinning of electronic devices, further reduction in size and thickness is required as a protective element built in the battery pack, and it is difficult to increase the distance between the first and second electrodes. In addition, with the increase in capacity and output of secondary batteries, there is a demand for higher protection element ratings.

Here, in order to raise the rating of the protective element, it is necessary to balance the reduction of the conductor resistance of the fusible conductor and the insulation performance when the current path is interrupted. That is, in order to flow a larger amount of current, it is necessary to reduce the conductor resistance, and thus it is necessary to increase the cross-sectional area of the soluble conductor. On the other hand, when the current path is interrupted, the metal body constituting the soluble conductor is scattered by the generated arc discharge, and a new current path may be formed, resulting in a large cross-sectional area of the soluble conductor. The higher the risk.

Also, when the protective element is melted by the heat of the heating element and melted by being drawn onto the first and second electrodes, increasing the cross-sectional area of the soluble conductor also increases the amount of the soluble conductor to be melted. It may increase and exceed the allowable amount that can be held on the electrode. In this case, the soluble conductor overflowing from the electrodes may cause a short circuit between the electrodes.

As described above, it is desired to develop a protective element capable of maintaining the insulation performance while increasing the cross-sectional area of the soluble conductor in order to improve the rating.

In order to solve the above-described problems, a protection element according to the present invention includes an insulating substrate, a heating element stacked on the insulating substrate, and an insulating member stacked on the insulating substrate so as to cover at least the heating element. And the first and second electrodes stacked on the insulating substrate on which the insulating member is stacked, and the first and second electrodes stacked on the insulating member so as to overlap the heating element. A heating element extraction electrode electrically connected to the heating element on a current path between the heating element extraction electrode and the first and second electrodes from the heating element extraction electrode. A fusible conductor that melts the current path between the second electrode and an inflow portion into which the melted fusible conductor flows is provided below the fusible portion of the fusible conductor. It is.

According to the present invention, by providing the inflow portion, the path between the heating element extraction electrode and each of the first and second electrodes can be made longer, and the molten conductor melted and scattered by the arc discharge adheres. However, it is possible to prevent the molten conductor from forming a current path between the heating element extraction electrode and each of the first and second electrodes, and to improve the insulation performance when the current path is interrupted. Can do.

FIG. 1A is a cross-sectional view showing a protective element to which the present invention is applied, and FIG. 1B is a plan view showing the protective element to which the present invention is applied. FIG. 2 is a circuit diagram of a battery pack incorporating a protection element to which the present invention is applied. FIG. 3 is an equivalent circuit of a protection element to which the present invention is applied. FIG. 4 is a cross-sectional view showing a fusing portion of the soluble conductor. FIG. 5 is a sectional view showing a modification of the protection element to which the present invention is applied. FIG. 6 is a cross-sectional view showing a modification of the protection element to which the present invention is applied. FIG. 7 is a cross-sectional view showing a modification of the protection element to which the present invention is applied. FIG. 8 is a sectional view showing a modification of the protection element to which the present invention is applied. FIG. 9 is a sectional view showing a modification of the protection element to which the present invention is applied. FIG. 10 is a cross-sectional view showing a modification of the protection element to which the present invention is applied.

Hereinafter, a protection element to which the present invention is applied will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention. Further, the drawings are schematic, and the ratio of each dimension may be different from the actual one. Specific dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[Configuration of protection element]
As shown in FIG. 1, a protection element 10 to which the present invention is applied is formed on an insulating substrate 11, a heating resistor 14 laminated on the insulating substrate 11 and covered with an insulating member 15, and both ends of the insulating substrate 11. Electrodes 12 (A 1) and 12 (A 2), a heating element extraction electrode 16 laminated on the insulating member 15 so as to overlap the heating resistor 14, and both ends of the electrodes 12 (A 1) and 12 (A 2) And a fusible conductor 13 having a central portion connected to the heating element extraction electrode 16.

The insulating substrate 11 is formed in a substantially square shape using an insulating member such as alumina, glass ceramics, mullite, zirconia, and the like. In addition, the insulating substrate 11 may be made of a material used for a printed wiring board such as a glass epoxy board or a phenol board, but it is necessary to pay attention to the temperature when the fuse is blown.

The heating resistor 14 is a conductive member that has a relatively high resistance value and generates heat when energized, and is made of, for example, W, Mo, Ru, or the like. These alloys, compositions, or compound powders are mixed with a resin binder or the like to form a paste on the insulating substrate 11 by patterning using a screen printing technique and firing.

The insulating member 15 is disposed so as to cover the heating resistor 14, and the heating element extraction electrode 16 is disposed so as to face the heating resistor 14 through the insulating member 15. In order to efficiently transfer the heat of the heating resistor 14 to the soluble conductor, an insulating member 15 may be laminated between the heating resistor 14 and the insulating substrate 11.

One end of the heating element extraction electrode 16 is connected to the heating element electrode 18 (P1). The other end of the heating resistor 14 is connected to the other heating element electrode 18 (P2).

The fusible conductor 13 is made of a low-melting-point metal that is quickly melted by the heat generated by the heating resistor 14, and, for example, Pb-free solder containing Sn as a main component can be suitably used. The soluble conductor 13 may be a laminate of a low melting point metal and a high melting point metal such as Ag, Cu, or an alloy containing these as a main component.

Even if the reflow temperature exceeds the melting temperature of the low melting point metal layer and the low melting point metal melts when the protective element 5 is reflow mounted by laminating the high melting point metal and the low melting point metal, the soluble conductor 13 does not lead to fusing. Such a soluble conductor 13 may be formed by depositing a low melting point metal on a high melting point metal by using a plating technique, or may be formed by using another known lamination technique or film forming technique. . The fusible conductor 13 can be solder-connected to the heating element extraction electrode 16 and the electrodes 12 (A1) and 12 (A2) using a low melting point metal constituting the outer layer.

Note that the protective element 5 may apply a flux to almost the entire surface of the soluble conductor 13 in order to prevent oxidation of the outer low-melting-point metal layer 13b. Further, the protection element 5 may place the cover member 19 on the insulating substrate 11 in order to protect the inside.

[How to use protection elements]
As shown in FIG. 2, the protection element 10 described above is used for a circuit in a battery pack 20 of a lithium ion secondary battery.

For example, the protective element 10 is used by being incorporated in a battery pack 20 having a battery stack 25 composed of battery cells 21 to 24 of a total of four lithium ion secondary batteries.

The battery pack 20 includes a battery stack 25, a charge / discharge control circuit 30 that controls charging / discharging of the battery stack 25, a protection element 10 to which the present invention that cuts off charging when the battery stack 25 is abnormal, and each battery cell. A detection circuit 26 for detecting voltages 21 to 24 and a current control element 27 for controlling the operation of the protection element 10 according to the detection result of the detection circuit 26 are provided.

The battery stack 25 is a series of battery cells 21 to 24 that need to be controlled to protect against overcharge and overdischarge states, and is detachable via the positive terminal 20a and the negative terminal 20b of the battery pack 20. Are connected to the charging device 35, and a charging voltage from the charging device 35 is applied thereto. The electronic device can be operated by connecting the positive electrode terminal 20a and the negative electrode terminal 20b of the battery pack 20 charged by the charging device 35 to the electronic device operated by the battery.

The charge / discharge control circuit 30 includes two

current control elements

31 and 32 connected in series to a current path flowing from the battery stack 25 to the charging device 35, and a control unit 33 that controls operations of the

current control elements

31 and 32. Is provided. The

current control elements

31 and 32 are configured by, for example, field effect transistors (hereinafter referred to as FETs), and control the gate voltage by the control unit 33 to control conduction and interruption of the current path of the battery stack 25. . The control unit 33 operates by receiving power supply from the charging device 35, and according to the detection result by the detection circuit 26, when the battery stack 25 is overdischarged or overcharged, current control is performed so as to cut off the current path. The operation of the

elements

31 and 32 is controlled.

Protective element 10 is connected, for example, on a charge / discharge current path between battery stack 25 and charge / discharge control circuit 30, and its operation is controlled by current control element 27.

The detection circuit 26 is connected to each of the battery cells 21 to 24, detects the voltage value of each of the battery cells 21 to 24, and supplies the voltage value to the control unit 33 of the charge / discharge control circuit 30. The detection circuit 26 outputs a control signal for controlling the current control element 27 when any one of the battery cells 21 to 24 becomes an overcharge voltage or an overdischarge voltage.

The current control element 27 is constituted by, for example, an FET, and when the voltage value of the battery cells 21 to 24 exceeds a predetermined overdischarge or overcharge state by a detection signal output from the detection circuit 26, the protection element 10 is operated to control the charge / discharge current path of the battery stack 25 to be cut off regardless of the switch operation of the

current control elements

31 and 32.

In the battery pack 20 configured as described above, the protection element 10 to which the present invention is applied has a circuit configuration as shown in FIG. That is, the protective element 10 generates heat by melting the soluble conductor 13 by causing the soluble conductor 13 connected in series via the heating element lead electrode 16 and the connection point of the soluble conductor 13 to generate heat. This is a circuit configuration including the resistor 14. In the protection element 10, for example, the fusible conductor 13 is connected in series on the charge / discharge current path, and the heating resistor 14 is connected to the current control element 27. One of the two electrodes 12 of the protection element 10 is connected to A1, and the other is connected to A2. Further, the heating element extraction electrode 16 and the heating element electrode 18 connected thereto are connected to P1, and the other heating element electrode 18 is connected to P2.

The protective element 10 having such a circuit configuration can surely melt the soluble conductor 13 on the current path by the heat generated by the heating resistor 14.

Note that the protection element of the present invention is not limited to use in a battery pack of a lithium ion secondary battery, and can of course be applied to various uses that require interruption of a current path by an electric signal.

[Fusing part]
Next, a more specific configuration of the protection element 10 to which the present invention is applied will be described. The protective element 10 is provided with an inflow portion 40 under which a molten conductor melted and scattered by arc discharge flows and deposits below a melted portion 13a where the soluble conductor 13 is melted. The fusible conductor 13 is connected across the heating element extraction electrode 16 and the electrodes 12 (A1) and 12 (A2), and melts due to self-heating (Joule heat) due to overcurrent and the heat of the heating resistor 14, The heating element extraction electrode 16 and the electrodes 12 (A1) and 12 (A2) are fused. Thereby, the protection element 13 interrupts the current path.

As shown in FIG. 4, the fusing part 13 a of the fusible conductor 13 refers to a fusing point in the fusible conductor 13 connected between the heating element extraction electrode 16 and the electrodes 12 (A1) and 12 (A2). Specifically, it means between the heating element extraction electrode 16 and the electrode 12 (A1) and between the heating element extraction electrode 16 and the electrode 12 (A2).

[Inflow section]
The protective element 10 is generated at the time of fusing due to overcurrent below the fusing portion 13a of the fusible conductor 13 connected between the heating element extraction electrode 16 and the electrodes 12 (A1) and 12 (A2). An inflow portion 40 is provided in which molten conductor melted and scattered by the arc discharge flowing in and deposits. The molten conductor that has melted and scattered in the inflow portion 40 flows in and accumulates to prevent the molten conductor from forming a current path between the heating element extraction electrode 16 and the electrodes 12 (A1) and 12 (A2). can do.

That is, the protective element 10 forms the inflow portion 40 below the fusing portion 13a, thereby extending the path between the heating element extraction electrode 16, the electrode 12 (A1), and the electrode 12 (A2). Therefore, even when the molten conductor adheres, the protective element 10 lengthens the path where the molten conductor adheres, so that the molten conductor causes the heating element extraction electrode 16 and the electrodes 12 (A1) and 12 (A2) to be connected. Thus, it is possible to prevent the current path extending over the range from being configured.

When the rating of the protective element 10 is increased by increasing the cross-sectional area of the fusible conductor 13, the molten conductor that melts and scatters due to arc discharge generated at the time of fusing also increases, but by providing the inflow portion 40 It is possible to prevent a current path from being formed by the molten conductor. Further, the protection element 10 can maintain the insulation performance without increasing the distance between the heating element extraction electrode 16 and the electrode 12 (A1) and the electrode 12 (A2), thereby realizing the downsizing of the protection element. be able to.

[Configuration 1 of the inflow section]
The inflow portion 40 is provided between the electrode 12 (A1) and the heating element extraction electrode 16, and between the electrode 12 (A2) and the heating element extraction electrode 16. That is, it is formed below the two fusing parts 13a in the soluble conductor 13 connected between the heating element extraction electrode 16 and the electrodes 12 (A1) and 12 (A2).

The inflow portion 40 may be provided only between the electrode 12 (A1) and the heating element extraction electrode 16 or between the electrode 12 (A2) and the heating element extraction electrode 16. In either case, if the formation of the current path by the molten conductor can be prevented, the charge / discharge path of the device in which the protection element 10 is incorporated is blocked. However, in order to ensure the maintenance of the insulation performance, the inflow portion 40 is preferably provided between the heating element extraction electrode 16 and each of the electrodes 12 (A1) and 12 (A2).

[Configuration 2 of the inflow section]
As shown in FIGS. 1 and 4, the inflow portion 40 can be constituted by a recess 41 formed in the insulating substrate 11. The recess 41 is formed in a groove shape between the electrode 12 (A1) of the insulating substrate 11 and the heating element extraction electrode 16 and between the electrode 12 (A2) and the heating element extraction electrode 16.

The recess 41 can be formed by a known method such as cutting or etching of the surface according to the material of the insulating substrate 11 or laminating the substrate according to the shape of the recess 41. By forming the recess 41, the protection element 10 can lengthen the path between the heating element extraction electrode 16 and each of the electrodes 12 (A1) and 12 (A2). Therefore, by flowing in the molten conductor that has been melted and scattered by arc discharge in the event of an overcurrent, the formation of a current path by the molten conductor can be prevented. Further, in the case of an overvoltage or the like, the protective element 10 has a case where the soluble conductor 13 melted by heat from the heating element extraction electrode 16 overflows from the electrodes 12 (A1) and 12 (A2) and the heating element extraction electrode 16. In addition, since the overflowing molten conductor flows into the recess 41, a short circuit between the heating element extraction electrode 16 and each of the electrodes 12 (A1) and 12 (A2) can be prevented.

Further, as shown in FIG. 5, the recess 41 may be formed so as to increase in diameter toward the lower side of the insulating substrate 11. Accordingly, the path between the heating element extraction electrode 16 and the electrodes 12 (A1) and 12 (A2) can be further extended, and the volume of the recess 41 can be increased. Therefore, the protection element 10 can more reliably prevent the formation of a current path even when the inflow amount of the molten conductor is large.

Moreover, it is preferable that the recessed part 41 has a larger volume than the deposition of the melted part 13a of the soluble conductor 13. Thereby, even when the molten conductor of the fusing part 13a flows into the recess 41, the protective element 10 prevents the molten conductor from overflowing from the recess 41 and prevents the current path from being formed by the overflowing molten conductor. be able to.

Moreover, it is preferable that the recessed part 41 is extended and extended to the outer side of the soluble conductor 13, as shown to FIG. 1B. By forming the recess 41 extending below and below the soluble conductor 13, the molten conductor of the melted melted portion 13 a is scattered to the outside of the soluble conductor 13 due to arc discharge that occurs during overcurrent. Even in this case, it is possible to prevent a current path from being formed by the molten conductor scattered to the outside.

[Configuration 3 of the inflow section]
Further, in the protection element 50, the inflow portion 40 may be constituted by a through hole 42 formed in the insulating substrate 11, as shown in FIG. Similar to the recess 41, the through hole 42 is formed in a groove shape between the electrode 12 (A 1) of the insulating substrate 11 and the heating element extraction electrode 16 and between the electrode 12 (A 2) and the heating element extraction electrode 16. Is formed.

The through hole 42 can be formed by a known method such as cutting or etching of the surface or laminating a substrate having an opening groove corresponding to the shape of the through hole 42 according to the material of the insulating substrate 11. . By forming the through hole 42, the protection element 50 can lengthen the path between the heating element extraction electrode 16 and the electrodes 12 (A1) and 12 (A2). By flowing and depositing the melted and scattered molten conductor, it is possible to prevent the current path from being formed by the molten conductor. Further, in the case of an overvoltage or the like, the protective element 50 is used when the soluble conductor 13 melted by heat from the heating element extraction electrode 16 overflows from the electrodes 12 (A1) and 12 (A2) and the heating element extraction electrode 16. In addition, since the overflowing molten conductor flows into the through-hole 42, a short circuit between the heating element extraction electrode 16 and each of the electrodes 12 (A1) and 12 (A2) can be prevented. At this time, by forming the inflow portion 40 with the through hole 42, the inflow portion 40 does not overflow even when the amount of the soluble conductor 13 overflowing from the electrode is large.

Further, the through hole 42 may also be formed so as to increase in diameter toward the lower side of the insulating substrate 11 as shown in FIG. Moreover, it is preferable that the through-hole 42 has a larger volume than the deposition of the fusing part 13a of the soluble conductor 13. Furthermore, as shown in FIG. 1B, the through hole 42 is preferably formed to extend to the outside of the soluble conductor 13.

[Configuration 4 of the inflow section]
Further, as shown in FIG. 8, the protective element 60 has a portion where the heating element extraction electrode 16 of the insulating substrate 11 is provided between the electrode 12 (A1) and the heating element extraction electrode 16 as shown in FIG. Alternatively, it may be formed by providing a protruding portion 43 that protrudes more than between the electrode 12 (A2) and the heating element extraction electrode 16. Thereby, in the protection element 60, the inflow portion 40 having a concave groove shape is formed below the melted portion 13a of the soluble conductor 13 between the protruding portion 43 and the electrodes 12 (A1) and 12 (A2).

The protrusion 43 can be formed by a known method such as cutting or etching of the surface, or laminating the substrate at a position where the heating element extraction electrode 16 is provided, depending on the material of the insulating substrate 11. By forming the protrusion 43, the protection element 60 can lengthen the path between the heating element extraction electrode 16 and each of the electrodes 12 (A1) and 12 (A2), thereby further improving the insulation performance. it can.

In addition, it is preferable that the inflow part 40 between the protrusion part 43 and the electrodes 12 (A1) and 12 (A2) has a larger volume than the deposition of the fusing part 13a of the soluble conductor 13. The inflow portion 40 between the protrusion 43 and the electrodes 12 (A1) and 12 (A2) extends to the outside of the soluble conductor 13 by providing the protrusion 43 to the outside of the soluble conductor 13. Preferably it is formed.

[Structure 5 of the inflow section]
Further, the protective element 70 may be formed by mounting the heating element module 45 on the insulating substrate 11 as shown in FIG. On the insulating substrate 11, electrodes 12 (A1) and 12 (A2) are formed. The heating element module 45 includes a base substrate 46, a heating resistor 14 laminated on the base substrate 46 and covered with an insulating member 15, and a heating element extraction electrode 16 formed so as to overlap the heating resistor 14. Have. Similar to the insulating substrate 11, the base substrate 46 is formed in a substantially rectangular shape using an insulating member such as alumina, glass ceramics, mullite, and zirconia. In addition, the base substrate 46 may be made of a material used for a printed wiring board such as a glass epoxy board or a phenol board. The heating resistor 14, the insulating member 15, and the heating element extraction electrode 16 are the same as those described above.

In the protective element 70, the heating element module 45 is mounted between the electrodes 12 (A1) and 12 (A2) of the insulating substrate 11 by an adhesive. Thereby, in the protective element 10, the inflow portion 40 is formed between the electrode 12 (A 1) and the electrode 12 (A 2) and the heating element module 45. Thus, the protective element 70 forms the heating element module 45 and mounts it on the insulating substrate 11, whereby the inflow portion 40 can be easily formed.

In addition, it is preferable that the heating element module 45 makes the volume of the inflow part 40 larger than the fusing part 13a of the soluble conductor 13 by forming the base substrate 46 thick. The heating element module 45 is preferably formed by extending the inflow portion 40 to the outside of the soluble conductor 13 by making the length of the base substrate 46 longer than that of the soluble conductor 13.

[Configuration 6 of the inflow section]
Moreover, as shown in FIG. 10, the protective element 80 may form the concave surface part 47 in the location which mounts the heat generating body module 45 of the insulating substrate 11. As shown in FIG. The concave portion 47 is provided wider than the base substrate 46 of the heating element module 45 between the electrodes 12 (A1) and 12 (A2) of the insulating substrate 11. The concave surface portion 47 is formed by a known method such as cutting or etching of the surface according to the material of the insulating substrate 11 or laminating the substrate according to the positions where the electrodes 12 (A1) and 12 (A2) are formed. can do.

The heating element module 45 is mounted on the concave portion 47 with a gap between the electrodes 12 (A1) and 12 (A2) and with an adhesive. Thereby, in the protective element 80, the inflow portion 40 is formed between the electrode 12 (A1) and the electrode 12 (A2) and the heating element module 45. Thus, the protection element 80 forms the heating element module 45 and mounts it on the insulating substrate 11, whereby the inflow portion 40 can be easily formed and the concave portion 47 is formed. , Low profile can be realized.

In addition, it is preferable that the heating element module 45 makes the volume of the inflow part 40 larger than the fusing part 13a of the soluble conductor 13 by deepening the concave surface part 47 and forming the base substrate 46 thick. The heating element module 45 is preferably formed by extending the inflow portion 40 to the outside of the soluble conductor 13 by making the lengths of the concave surface portion 47 and the base substrate 46 longer than the soluble conductor 13.

[Depth of Inflow Portion 40]
In any of the

protection elements

10, 50, 60, 70, 80 described above, the insulation performance can be improved as the depth of the inflow portion 40 is increased. That is, the

protection elements

10, 50, 60, 70, 80 have longer paths between the heating element extraction electrode 16 and the electrodes 12 (A1), 12 (A2) as the depth of the inflow portion 40 is increased. Even if the molten conductor melted and scattered by the arc discharge adheres, the molten conductor forms a current path between the heating element extraction electrode 16 and the electrodes 12 (A1) and 12 (A2). Because it becomes difficult.

10, 50, 60, 70, 80 Protection element, 11 Insulating substrate, 12 Electrode, 13 Soluble conductor, 13a Fusing part, 14 Heating element, 15 Insulating member, 16 Heating element extraction electrode, 18 Heating element electrode, 19 Cover member , 20 battery pack, 21-24 battery cells, 26 detection circuit, 27 current control element, 30 charge / discharge control circuit, 31, 32 current control element, 33 control unit, 35 charging device, 40 inflow unit, 41 recess, 42 penetration Hole, 45 heating element module, 46 base substrate, 47 concave surface

Claims

An insulating substrate;
A heating element laminated on the insulating substrate;
An insulating member laminated on the insulating substrate so as to cover at least the heating element;
First and second electrodes stacked on the insulating substrate on which the insulating member is stacked;
A heating element extraction electrode laminated on the insulating member so as to overlap the heating element and electrically connected to the heating element on a current path between the first and second electrodes;
A laminate that extends from the heating element extraction electrode to the first and second electrodes, and includes a soluble conductor that melts a current path between the first electrode and the second electrode by heat;
The protective element provided with the inflow part into which the said melt | dissolved soluble conductor flows in under the melt | fusion part of the said soluble conductor.
The protective element according to claim 1, wherein the inflow portion is provided between the first electrode and the heating element extraction electrode and / or between the second electrode and the heating element extraction electrode.
3. The protective element according to claim 1, wherein the inflow portion is a recess formed in the insulating substrate.
The protective element according to claim 3, wherein the inflow portion has a diameter expanded toward a lower side of the insulating member.
The protective element according to claim 1 or 2, wherein the inflow portion is a through hole formed in the insulating substrate.
The protective element according to claim 5, wherein the inflow portion has a diameter expanded toward a lower side of the insulating member.
The inflow portion has a place where the heating element extraction electrode of the insulating substrate is provided between the first electrode and the heating element extraction electrode and between the second electrode and the heating element extraction electrode. The protective element according to claim 1, wherein the protective element is formed by projecting from a gap.
3. The inflow portion is formed by mounting a heating element module in which the heating element, the insulating member, and the heating element extraction electrode are formed on a base substrate on the insulating substrate. The protective element as described in.
The protective element according to claim 7, wherein a portion of the insulating member where the heating element module is mounted is lower than a portion where the first and second electrodes are stacked.
The protective element according to claim 1 or 2, wherein the volume of the inflow portion is larger than the volume of the melted portion of the soluble conductor.
The protective element according to claim 1 or 2, wherein the inflow portion is formed to extend to the outside of the soluble conductor.