WO2014021156A1

WO2014021156A1 - Protective element and battery pack

Info

Publication number: WO2014021156A1
Application number: PCT/JP2013/069995
Authority: WO
Inventors: 武雄木村; 後藤　一夫; 吉弘米田
Original assignee: デクセリアルズ株式会社
Priority date: 2012-08-01
Filing date: 2013-07-24
Publication date: 2014-02-06
Also published as: CN104508783A; JP2014032769A; JP5952674B2; HK1208760A1; TW201419350A; KR20150040954A

Abstract

In order to obtain a protective element that can be easily made to fuse and that reliably divides molten solder, a protective element (10) is provided with: an insulating substrate (11), a heating element (14) that is layered on the insulating substrate (11) and that is covered by an insulating member (15); electrodes (12)(A1) and (12)(A2); a heating element-drawing electrode (16) that is layered on the insulating member (15) so as to overlap with the heating element (14); a protective layer (6) that is formed so as to surround the peripheral edge section of the heating element-drawing electrode (16); and a fusible conductor (13), both ends of which are connected to the electrodes (12)(A1) and (12)(A2) and the central section of which is connected to the heating element-drawing electrode (16) at an opening (6a) in the protective layer (6). The fusible conductor (13) comprises a thick section (13a) and a thin section (13b) that is molded so as to be thin and flat. The protective layer (6) opens at a section of said protective layer that connects with the thin section (13b) of the fusible conductor (13) and the heating element-drawing electrode (16), and is formed so as to surround the peripheral edge of the heating element-drawing electrode (16).

Description

Protective element and battery pack

The present invention relates to a protective element that protects a circuit connected on a current path by fusing the current path. This application claims priority on the basis of Japanese Patent Application No. 2012-171333 filed on Aug. 1, 2012 in Japan, and is incorporated herein by reference. Is done.

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.

In many electronic devices using lithium ion secondary batteries, an overcharge protection or an overdischarge protection operation of the battery pack is performed 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, a lightning surge or the like is applied, and an instantaneous large current flows, or the output voltage drops abnormally due to the life of the battery cell. The battery pack and the electronic device must be protected from accidents such as ignition even when the is output. Accordingly, 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 such a protection circuit for a lithium ion secondary battery or the like, as described in Patent Document 1, a heating element is provided inside the protection element. A structure that melts a molten conductor is generally used.

JP 2010-3665 A

In the protective element described in Patent Document 1, the fusible conductor (fuse) has a current capacity of about 15 A at the maximum because it is used for applications having a relatively low current capacity such as a mobile phone or a notebook computer. is doing. Applications of lithium ion secondary batteries have been expanding in recent years, and their use in higher current applications such as electric tools such as electric drivers, transportation equipment such as hybrid cars, electric vehicles, and electric power assisted bicycles has been studied. Part recruitment has begun. In these applications, a large current exceeding several tens of A to 100 A may flow particularly at startup. Realization of a protection element corresponding to such a current capacity is desired.

In order to realize a protective element corresponding to a large current, the cross-sectional area of the soluble conductor may be increased. When Sn / Ag / Cu solder molded into a 1.6 mmφ line is used, a current capacity of about 50 A can be obtained. However, the protection element needs to detect the overvoltage state of the battery cell, flow current through the resistance heating element of the protection element, and cut the soluble conductor by the heat generation, in addition to the case where the protection element is melted by an overcurrent state. is there. For this reason, the “thick” soluble conductor has a problem that heat conduction from the heating element is lowered and it is difficult to cut the soluble conductor. Further, when the “thick” fusible conductor is blown, there is a problem that the circuit cannot be cut off unless the melted solder is surely cut.

Therefore, an object is to obtain a protective element that can be easily blown by heat generated by a heating element while ensuring a current capacity at the time of overcurrent protection, and can reliably cut off a circuit by dividing molten solder. And

As a means for solving the above-described problem, a protection element according to the present invention includes an insulating substrate, a heating element that is stacked on the insulating substrate, and has two terminals for receiving a current supply from an external power source, and at least An insulating member laminated on the insulating substrate so as to cover the heating element, the first and second electrodes, and laminated on the insulating member so as to overlap the heating element, and between the first and second electrodes A heating element extraction electrode that is electrically connected to the current path of the heating element and one heating element terminal of the heating element, and is electrically connected to an external circuit, and laminated on a part of the heating element extraction electrode, And a soluble conductor that is connected across the first and second electrodes from the heating element extraction electrode and that melts the current path between the first electrode and the second electrode by heating. The fusible conductor is connected at a portion where the heating element extraction electrode and the protection layer of the heating element extraction electrode are not stacked, and the protection layer is stacked at a position where a connection with an external circuit is secured by one heating element terminal. .

The battery pack according to the present invention includes one or more battery cells, a protection element connected to cut off a current flowing through the battery cell, and a current for detecting the voltage value of each battery cell and heating the protection element. A current control element to be controlled. Then, the protective element is laminated on the insulating substrate so as to cover the insulating substrate, the heating element that is laminated on the insulating substrate, and has two terminals for receiving a current supply from an external power source, and at least the heating element. The insulating member, the first and second electrodes, and the heat generating element are stacked on the insulating member so as to overlap with each other, and a current path between the first and second electrodes and one heat generating terminal of the heat generating element, A heating element extraction electrode electrically connected to the external circuit, a protective layer made of an insulating material, laminated on a part of the heating element extraction electrode, and a first and A fusible conductor connected over the second electrode and fusing a current path between the first electrode and the second electrode by heating, wherein the fusible conductor comprises a heating element extraction electrode and a heating element extraction; The electrode is connected at a portion where the protective layer is not laminated. The heating element terminals are stacked in a position to secure the connection with the external circuit.

The present invention forms a protective layer on a part of the heating element extraction electrode, connects the thin part of the soluble conductor at a place where the protective layer does not exist, and causes solder corrosion phenomenon at the place where the thin part is connected. It can be generated, and the molten solder can be stably divided and the circuit can be interrupted.

FIG. 1A is a plan view of a protection element to which the present invention is applied. FIG. 1B is a cross-sectional view taken along the line AA ′ of FIG. FIG. 1C is a plan view of the fusible conductor in a melted state. 2A to 2C are plan views for explaining a process for manufacturing a protective element to which the present invention is applied. 3A to 3B are plan views showing variations in the shape of the protective layer of the protective element to which the present invention is applied. FIG. 4 is a block diagram showing an application example of a protection element to which the present invention is applied. FIG. 5 is a diagram showing a circuit configuration example of a protection element to which the present invention is applied.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited only to the following embodiment, Of course, a various change is possible in the range which does not deviate from the summary of this invention.

[Configuration of protection element]
As shown in FIGS. 1A and 1B, the protection element 10 includes an insulating substrate 11, a heating element 14 laminated on the insulating substrate 11 and covered with an insulating member 15, and both ends of the insulating substrate 11. The electrodes 12 (A 1), 12 (A 2) formed on the insulating member 15, the heating element extraction electrode 16 stacked on the insulating member 15 so as to overlap the heating element 14, and the peripheral edge of the heating element extraction electrode 16 are surrounded. And a soluble conductor 13 whose both ends are connected to the electrodes 12 (A1) and 12 (A2), and whose central portion is connected to the heating element extraction electrode 16 at the opening 6a of the protective layer 6. Is provided. At both ends of the heating element 14, heating element electrodes 18 (P1) and 18 (P2) are connected to which a power source is connected in order to cause the heating element to generate current and generate heat.

The soluble conductor 13 is preferably thick so that the thickness thereof is substantially uniform at the position where the portion facing the heating element 14 and the thick portion 13a having a round line shape of 1.6 mmφ overlap the heating element 14. It consists of a thin part 13b which is thinner and flatter than the meat part 13a. The thickness of the thin portion 13b is, for example, 1/2 of the thickness (thickness) of the thick portion 13a. In addition, it is preferable that the cross-sectional area of the thick part 13a and the thin part 13b is substantially the same. The thin portion 13 b of the soluble conductor 13 is electrically connected to the heating element extraction electrode 16.

By making the fusible conductor 13 a thin portion 13b where the position overlapping the heating element 14 is reduced, the heat conduction in the thickness direction of the thin portion 13b is improved and the contact area with the heat source is also increased. Due to the heat generated by the heating element 14, the fusible conductor 13 can be easily melted. In addition, when the cross-sectional area of the thick part 13a and the thin part 13b is made the same, the current capacity does not change, depending on the cross-sectional area in the energizing direction of the soluble conductor 13 and the material (specific resistance) of the soluble conductor 13 Current can flow.

The heating element extraction electrode 16 is usually patterned by Cu or Ag (Ag paste or the like), but these metals (or alloys containing these metals as main components) are melted when the solder constituting the soluble conductor 13 is melted. A solder corrosion phenomenon that dissolves in molten solder is known. In the conventional protective element having a current capacity of up to about 15 A, the amount of soluble conductor (solder) is smaller than the amount of metal used for the heating element extraction electrode, so there is no need to consider the solder corrosion phenomenon. . Here, when the “thick” solder is used as the soluble conductor 13 in accordance with the increase in the current capacity of the protection element, solder corrosion occurs during the operation of the protection element 10, and heat is generated during the operation of the protection element. There is a problem that the body extraction electrode 16 disappears, the power supply to the heating element 14 is stopped, and the fusing operation is stopped.

Also, in the fusing operation of the fusible conductor 13, if molten solder stays on the heating element extraction electrode 16, the amount of solder corresponding to a large current is large, so that reliable division of the molten solder becomes a problem. Therefore, it is considered to positively utilize the solder erosion phenomenon to further ensure melting of the molten solder.

When a solder corrosion phenomenon occurs in the connecting portion between the heating element extraction electrode 16 and the thin portion 13b of the soluble conductor 13, the metal constituting the heating element extraction electrode 16 disappears, and the base of the heating element extraction electrode 16 is lost. A certain insulating member 15 is exposed, and the molten solder is less likely to stay and can flow out to another path. Here, if all of the heating element extraction electrode 16 connected to the thin wall portion 13b disappears due to the solder corrosion phenomenon, power supply to the heating body 14 becomes impossible, and the molten state of the thin wall portion 13b is maintained. become unable. Thus, the protective layer 6 is formed on the heating element extraction electrode 16 so as to leave a current-carrying path to the heating element 14, and the heating element extraction electrode 16 is lost while maintaining the power supply to the heating element 14. Promotes the melting of molten solder.

Specifically, as shown in FIG. 1A, the protective layer 6 opened so that a part of the heating element extraction electrode 16 is exposed is formed on the heating element extraction electrode 16. The heating element extraction electrode 16 is extended in a direction different from the longitudinal direction of the fusible conductor 13, for example, in a direction perpendicular to the longitudinal direction of the fusible conductor 13, and one of the extended sides is a thin portion 13 b of the fusible conductor 13. The other connected and extended side is connected to an electrode 18a (P1) for the heating element 14 formed on the insulating member 15. The protective layer 6 is opened at a portion where the thin portion 13 b of the soluble conductor 13 and the heating element extraction electrode 16 are connected, and is formed so as to surround the periphery of the heating element extraction electrode 16.

When the electric power is supplied to the heating element 14 to generate heat, the thin portion 13b of the soluble conductor 13 starts to melt. The solder constituting the thin portion 13b melts at a high temperature, and the metal constituting the heating element extraction electrode 16 connected to the thin portion 13b through the opening 6a of the protective layer 6 causes solder corrosion and melts. Dissolve in the solder. As a result, the heating element extraction electrode 16 disappears at the place where the soluble conductor 13 on the insulating member 15 is disposed, and the insulating member 15 is exposed. As a result, as shown in FIG. 1C, the molten solder of the soluble conductor 13 cannot stay on the insulating member 15 and the protective layer 6 having low wettability, and the melting of the molten solder is promoted.

The protective layer 6 can be formed as shown in FIGS. As shown in FIG. 2A, the heating element extraction electrode 16 is patterned on the insulating member 15 by using a known printing technique or the like. At this time, electrodes 18a (P1) and 18a (P2) for the heating element 14 may be formed at the same time. As shown in FIG. 2B, the protective layer 6 is formed so as to be annularly laminated around the heating element extraction electrode 16. As shown in FIG. 2C, an insulating member 15 (a laminated substrate on which the heating element 14 is laminated) on which the protective layer 6 is formed is soldered on the insulating substrate 11. Thereafter, the soluble conductor is placed so that the thin portion 13b of the soluble conductor 13 is connected to the opening 6a of the protective layer 6. For the protective layer 6, for example, a well-known insulating material having heat resistance such as glass or polyimide can be used.

The two electrodes 12 (A1) and 12 (A2) connect the fusible conductor 13 inside the protective element 10, and are connected to an external circuit through the two electrodes 12 (A1) and 12 (A2). To do. The two electrodes 12 (A 1) and 12 (A 2) may be formed on the insulating substrate 11, or may be formed on an insulating material made of an epoxy resin or the like integrated with the insulating substrate 11.

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

The insulating substrate 11 is formed of an insulating member such as alumina, glass ceramics, mullite, zirconia, or the like. In addition, although the material used for printed wiring boards, such as a glass epoxy board | substrate and a phenol board | substrate, may be used, it is necessary to pay attention to the temperature at the time of fuse blowing.

The heating element 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.

An insulating member 15 is disposed so as to cover the heating element 14, and a heating element extraction electrode 16 is disposed so as to face the heating element 14 through the insulating member 15. Of course, the insulating member 15 may be a laminated substrate in which the heating elements 14 are integrally laminated.

The fusible conductor 13 may be any conductive material that melts and melts due to the overcurrent state and the heat generated by the heating element 14. For example, in addition to SnAgCu-based Pb-free solder, BiPbSn alloy, BiPb alloy, BiSn An alloy, SnPb alloy, PbIn alloy, ZnAl alloy, InSn alloy, PbAgSn alloy, or the like can be used.

Further, the soluble conductor 13 may be a laminate of a high melting point metal made of a metal mainly composed of Ag or Cu or Ag or Cu and a low melting point metal such as Pb-free solder mainly composed of Sn. Good.

In order to support the fusible conductor 13 with respect to the insulating substrate 11 and improve the mechanical strength of the fusible conductor 13, the support member 3 is formed on the electrode 2 formed on the insulating substrate 11. The fusible conductor 13 may be connected to the support member 3.
[Modification]

The protective layer 6 can be formed so as to ensure the connection with the external circuit through the path to the electrode 18a (P1) on the side where the heating element extraction electrode 16 extends. In the above-described embodiment, the protective layer 6 is formed so as to surround the periphery of the heating element extraction electrode 16, but the heating element is located at the intersection of the heating element extraction electrode 16 and the thin portion 13 b of the soluble conductor 13. The protective layer 6 may be formed so as to cover the metal portion of the extraction electrode 16.

Therefore, as shown in FIG. 3A, the protective layer 6 may be formed so as to cover the edges on both sides of the heating element extraction electrode 16. Further, as shown in FIG. 3B, the protective layer 6 may be formed so as to cover the edge on one side of the heating element extraction electrode 16. In any case, the protective layer 6 is formed at the position where the soluble conductor 13 and the heating element extraction electrode 16 intersect for the purpose of preventing solder corrosion.
[How to use protection elements]

As shown in FIG. 4, the protection element 10 described above is used in a circuit in a battery pack 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 charge / discharge of the battery stack 25, a protection element 10 to which the present invention that protects the battery stack 25 and the charge / discharge control circuit 30 is applied, A detection circuit 26 that detects the voltages of the battery cells 21 to 24 and a current control element 27 that controls the operation of the protection element 10 according to the detection result of the detection circuit 26 are provided.

The battery stack 25 includes battery cells 21 to 24 that need to be controlled to protect overcharge and overdischarge states. The battery stack 25 is detachable via the positive electrode terminal 20a and the negative electrode 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 battery pack 20 charged by the charging device 35 to the positive terminal 20a and the negative terminal 20b to the electronic device that is 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 operates the protection element 10 when the voltage value of the battery cells 21 to 24 exceeds a predetermined overdischarge or overcharge state by the detection signal output from the detection circuit 26, Control is performed so that the charging / discharging current path of the battery stack 25 is cut off regardless of the switching operation of the

current control elements

31 and 32.

In the battery pack 20 having the above configuration, the configuration of the protection element 10 will be specifically described.

First, 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 comprising the body 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 element 14 is connected to the current control element 27. Of the two

electrodes

12 and 12 of the protective element 10, one 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 generation of the heating element 14 while realizing a low profile.

2 electrode, 3 support member, 6 protective layer, 6a opening, 10 protective element, 11 insulating substrate, 12 (A1), 12 (A2) electrode, 13 soluble conductor, 13a thick part, 13b thin part, 14 heating element , 15 insulation member, 16 heating element extraction electrode, 18 (P1), 18 (P2) heating element electrode, 18a (P1), 18a (P2) electrode, 20 battery pack, 20a positive terminal, 20b negative terminal, 21-24 Battery cell, 25 battery stack, 26 detection circuit, 27, 31, 32 current control element, 30 charge / discharge control circuit, 33 control unit, 35 charging device

Claims

An insulating substrate;
A heating element laminated on the insulating substrate and having two terminals for receiving a current from an external power source;
An insulating member laminated on the insulating substrate so as to cover at least the heating element;
First and second electrodes;
It is laminated on the insulating member so as to overlap with the heating element, and is electrically connected to the current path between the first and second electrodes and one heating element terminal of the heating element, and externally A heating element extraction electrode in electrical connection with the circuit;
A protective layer made of an insulating material, laminated on a part of the heating element extraction electrode;
A soluble conductor that is connected from the heating element extraction electrode to the first and second electrodes and that melts a current path between the first electrode and the second electrode by heating;
The fusible conductor is connected at a portion where the heating element extraction electrode and the protection layer of the heating element extraction electrode are not laminated, and the protection layer is secured at a position where the one heating element terminal is connected to an external circuit. A protective element which is laminated on the substrate.
The heating element extraction electrode extends in the direction of the one heating element terminal in a direction different from the longitudinal direction of the soluble conductor, and the protective layer is formed along the direction in which the heating element extraction electrode extends. The protective element according to claim 1, wherein:
The protective layer is formed along a direction in which the heating element extraction electrode extends, and is disposed so as to surround a periphery of an electrical connection portion of the heating element extraction electrode with the soluble conductor. The protective element according to claim 1.
2. The protective element according to claim 1, wherein the heating element extraction electrode is made of Ag or Ag as a main component or Cu or Cu as a main component.
2. The protection element according to claim 1, wherein the soluble conductor includes a thick portion and a thin portion formed in a concave shape with a portion located so as to overlap the heating element being thin and flat. .
6. The protective element according to claim 5, wherein the soluble conductor has substantially the same cross-sectional area in the thick part and the thin part.
One or more battery cells;
A protective element connected to cut off the current flowing through the battery cell;
A current control element that detects a voltage value of each of the battery cells and controls a current for heating the protection element;
The protective element is
An insulating substrate;
A heating element laminated on the insulating substrate and having two terminals for receiving a current from an external power source;
An insulating member laminated on the insulating substrate so as to cover at least the heating element;
First and second electrodes;
It is laminated on the insulating member so as to overlap with the heating element, and is electrically connected to the current path between the first and second electrodes and one heating element terminal of the heating element, and externally A heating element extraction electrode in electrical connection with the circuit;
A protective layer made of an insulating material, laminated on a part of the heating element extraction electrode;
A soluble conductor which is connected from the heating element extraction electrode to the first and second electrodes and melts a current path between the first electrode and the second electrode by heating;
The fusible conductor is connected at a portion where the heating element extraction electrode and the protection layer of the heating element extraction electrode are not laminated, and the protection layer is secured at a position where the one heating element terminal is connected to an external circuit. A battery pack that is stacked on the battery pack.