TW201419351A - Protective element and battery pack - Google Patents

Abstract

In order to obtain a protective element that can be easily made to fuse and that is capable of reliably dividing 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 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); 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), said heating element-drawing electrode (16) being provided with a protective layer (8). 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 form of the heating element-drawing electrode (16) that is extended in the lengthwise direction of the fusible conductor (13) and in the direction that is perpendicular to said lengthwise direction is set so that the area of the electrode (18a)(P1) side of the heating element (14) is larger than the area at the connecting position of the heating element-drawing electrode (16) and the thin section (13b) of the fusible conductor (13).

Description

Protection component and battery pack

The present invention relates to a protection element that protects a circuit connected to a current path by blowing a current path. The present application claims priority on the basis of Japanese Patent Application No. 2012-171332, filed on Jan.

Most of the rechargeable and reusable secondary batteries are processed into a battery pack and supplied to the user. In particular, in a lithium ion secondary battery having a high weight and energy density, in order to secure the safety of the user and the electronic device, in general, a plurality of protection circuits such as overcharge protection and overdischarge protection are built in the battery pack. And has the function of blocking the output of the battery pack under certain circumstances.

In most electronic devices using lithium ion secondary batteries, ON/OFF (on/off) of the output is performed by using a FET (Field Effect Transistor) switch built in the battery pack. Perform overcharge protection or overdischarge protection of the battery pack. However, even when the FET switch is short-circuited by some reason, the output voltage is abnormally lowered when a large current flows instantaneously due to a lightning surge or the like, or the output voltage is abnormally lowered due to the life of the battery unit, or On the contrary, when the output of excessive abnormal voltage is exceeded, it is necessary to protect the battery pack or the electronic device from accidents such as fire. Therefore, in any abnormal state that can be assumed, in order to safely block the output of the battery unit, the use has A protective element consisting of a fuse element that blocks the function of the current path.

As a protective element applied to a protective circuit for a lithium ion secondary battery or the like, as described in Patent Document 1, generally, a structure is provided in which a heat generating body is provided inside the protective element, and a current is blown by heat generation of the heat generating body. A fusible conductor on the path.

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

In the protective element described in Patent Document 1, the meltable conductor (fuse) has a current capacity of at most about 15 A in order to be used for a mobile phone or a personal computer having a low current capacity. The use of lithium ion secondary batteries has been expanding in recent years, and the use of larger currents, for example, has been carried out using power tools such as electric screwdrivers, hybrid electric vehicles, electric vehicles, and electric auxiliary bicycles. In such applications, especially at the time of startup, there are cases where a large current of more than 10A to 100A is circulated. It is desirable to have a protective element that corresponds to such a large current capacity.

In order to realize a protection element corresponding to a large current, it is only necessary to increase the cross-sectional area of the fusible conductor. When a Sn/Ag/Cu solder which is formed into a line shape of 1.6 mmφ is used, a current capacity of about 50 A can be obtained. However, in addition to the case where the protection element is blown by the overcurrent state, it is also necessary to detect the overvoltage state of the battery cell, and the current flows to the resistance heating element of the protection element, and the fusible conductor is cut by the heat generation. Therefore, in the case of the "thick" fusible conductor, there is a problem in that the heat conduction from the heating element is lowered, and it becomes difficult to cut the soluble conductor. Further, in the case where the "thick" fusible conductor is blown, if the molten solder is not reliably separated, there is a problem that the circuit cannot be blocked.

Accordingly, it is an object of the invention to obtain a protective element that ensures over-powering The current capacity at the time of current protection is also easily fused by the heat generation of the heat generating body, and the molten solder can be reliably separated to block the circuit.

As a means for solving the above problems, the protective element of the present invention includes: an insulating substrate; a heat generating body laminated on the insulating substrate; and an insulating member laminated on the insulating substrate so as to cover at least the heat generating body; a second electrode; a heating element extraction electrode laminated on the insulating member so as to overlap the heating element, and electrically connected to the current path between the first and second electrodes and one of the terminals of the heating element, and electrically connected to the external circuit The fusible conductor is connected so that the self-heating body extraction electrode straddles the first and second electrodes, and the current path between the first electrode and the second electrode is blown by heating. Further, the heating element extraction electrode is disposed so as to extend in a direction different from the longitudinal direction of the soluble conductor, and the area on the side where the heating element extraction electrode extends is larger than the area of the connection position between the heating element extraction electrode and the fusible conductor.

The battery pack of the present invention comprises: one or more battery cells; a protection element connected to block a current flowing through the battery cells; and a current control component that detects a voltage value of each of the battery cells to control a current of the heating protection component . Further, the protective element includes: an insulating substrate; and a heat generating body laminated on the insulating substrate: an insulating member laminated on the insulating substrate so as to cover at least the heat generating body; first and second electrodes; and a heat generating body lead electrode; Laminated over the insulating member so as to overlap the heating element, and electrically connected to the current path between the first and second electrodes and one of the terminals of the heating element, and electrically connected to the external circuit; the fusible conductor The heating element extraction electrode is connected across the first and second electrodes, and the current path between the first electrode and the second electrode is melted by heating; the heating element extraction electrode is disposed differently from the length direction of the fusible conductor In the direction extending, the area on the side where the heating element lead-out electrode extends is larger than the area where the heating element extraction electrode and the fusible conductor are connected.

The shape of the heating element extraction electrode of the present invention is arranged to extend in a direction different from the longitudinal direction of the fusible conductor, and the area of the extension side of the heating element extraction electrode is larger than the area of the connection position between the extraction electrode of the heating element and the fusible conductor, and thus is melted. The solder is close to the side of the larger area, whereby the molten solder can be stably separated.

2‧‧‧electrode

3‧‧‧Support members

8‧‧‧Protective film

10‧‧‧Protection components

11‧‧‧Insert substrate

12 (A1), 12 (A2) ‧ ‧ electrodes

13‧‧‧Solid conductor

13a‧‧‧ Thick Wall

13b‧‧‧thin wall

14‧‧‧heating body

15‧‧‧Insulating components

16‧‧‧heating body extraction electrode

18 (P1), 18 (P2) ‧ ‧ heating body electrodes

18a (P1), 18a (P2) ‧ ‧ electrodes

20‧‧‧Battery Pack

20a‧‧‧positive terminal

20b‧‧‧Negative terminal

21~24‧‧‧ battery unit

25‧‧‧Battery stack

26‧‧‧Detection circuit

27, 31, 32‧‧‧ Current Control Components

30‧‧‧Charge and discharge control circuit

33‧‧‧Control Department

35‧‧‧Charging device

Figure 1 (A) is a plan view of a protective element to which the present invention is applied. Fig. 1(B) is a cross-sectional view taken along line AA' of Fig. 1(A).

2(A) to (C) are plan views for explaining the fusing action of the protective element to which the present invention is applied.

Fig. 3 is a block diagram showing an application example of a protective element to which the present invention is applied.

Fig. 4 is a view showing an example of a circuit configuration of a protective element to which the present invention is applied.

5(A) to 5(D) are plan views showing deformations of the shape of the heat generating body lead-out electrode to which the protective element of the present invention is applied.

Fig. 6(A) is a plan view showing a heat generating body extraction electrode according to a modification of the present invention. Fig. 6(B) is a cross-sectional view taken along line AA' of Fig. 6(A).

Hereinafter, the form for carrying out the present invention will be described in detail with reference to the drawings. It is a matter of course that the present invention is not limited to the embodiments described below, and various modifications can be made without departing from the spirit and scope of the invention.

[Composition of protective components]

In order to separate the molten solder and to reliably block the circuit, the protective element of the present invention is conceived The heat generating body described below extracts the shape of the electrode.

As shown in FIG. 1(A) and FIG. 1(B), the protective element 10 includes an insulating substrate 11 and a heat generating body 14 laminated on the insulating substrate 11 and covered with an insulating member 15; the electrode 12 (A1), 12 (A2), which is formed at both ends of the insulating substrate 11; a heating element extraction electrode 16 which is laminated on the insulating member 15 so as to overlap with the heating element 14; and a fusible conductor 13 whose both ends are connected to the electrode 12 ( A1), 12 (A2). Heat generating body electrodes 18 (P1) and 18 (P2) connected to a power source are connected to both ends of the heating element 14 to cause a current to flow to the heat generating body to generate heat. The fusible conductor 13 is preferably composed of a thick-walled portion 13a and a thin portion 13b having a circular shape of 1.6 mmφ, and the thin portion 13b is formed so as to be substantially uniform in thickness at a position overlapping the heating element 14. It is formed in a flat shape thinner than the thick portion 13a. The thickness of the thin portion 13b is, for example, 1/2 of the thickness (thickness) of the thick portion 13a. Further, the cross-sectional area or current capacity of the thick portion 13a and the thin portion 13b is preferably substantially the same. The thin portion 13b of the fusible conductor 13 is electrically connected to the heating element extraction electrode 16.

By forming the meltable conductor 13 into the thin portion 13b which is thinned at the position of the heat generating body 14, the heat conduction in the thickness direction of the thin portion 13b can be improved, and the meltable conductor 13 can be easily melted. Further, by forming the thin portion 13b in a flat shape, the contact area with the overlapping portion of the heating element 14 can be increased, and the heat from the heating element 14 can be efficiently transmitted, and stable melting characteristics can be realized. In the case where the cross-sectional areas of the thick portion 13a and the thin portion 13b are substantially the same, the current capacity of the soluble conductor 13 is the same, and the cross-sectional area corresponding to the energizing direction of the soluble conductor 13 can be circulated. The current of the material (specific resistance) of the fusible conductor 13.

The two electrodes 12 (A1), 12 (A2) are connected to the inside of the protective element 10 to connect the fusible conductor 13, and are connected to an external circuit via the two electrodes 12 (A1), 12 (A2). The two electrodes 12 (A1), 12 (A2) may be formed on the insulating substrate 11, or may be formed on the The edge substrate 11 is an insulating material made of an epoxy resin or the like.

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. Further, 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, for example, an insulating member such as alumina, glass ceramic, mullite, or zirconia. Further, a material for a printed circuit board such as a glass epoxy substrate or a phenol substrate may be used, but it is necessary to pay attention to the temperature at which the fuse is blown.

The heating element 14 is a member having a relatively high electric resistance value and which generates heat when energized, and is made of, for example, W, Mo, Ru, or the like. The alloy or the composition, the powder of the compound, the resin binder, and the like are mixed, and the paste is formed on the insulating substrate 11 by a screen printing technique pattern, and is baked or the like.

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

The fusible conductor 13 may be a material that is melted and melted by an overcurrent state and heat generated by the heating element 14, and for example, SnAgCu-based Pb-free solder may be used, and BiPbSn may be used. Alloy, BiPb alloy, BiSn alloy, SnPb alloy, PbIn alloy, ZnAl alloy, InSn alloy, PbAgSn alloy, and the like.

Further, the fusible conductor 13 may be a laminate of a high melting point metal composed of Ag or Cu or a metal containing Ag or Cu as a main component, and the low melting point metal is made of Sn. The main component is Pb-free solder or the like.

Further, in order to support the soluble conductor 13 to the insulating substrate 11 and to improve the mechanical strength of the meltable conductor 13, a supporting member may be formed on the electrode 2 formed on the insulating substrate 11. 3. Connect the fusible conductor 13 to the support member 3.

In the protective element of the present invention, a "thick" fusible conductor is used in order to correspond to a large current capacity. In the case where the fusible conductor is blown, the amount of the molten solder is large, and in order to surely separate the molten solder and block the circuit, it is necessary to consider the treatment of the molten solder.

Therefore, as shown in FIG. 1(A), the heating element extraction electrode 16 is extended in a direction perpendicular to the soluble conductor 13, for example, in a direction perpendicular to the longitudinal direction of the soluble conductor 13, and is connected to one side of the extension. The thin portion 13b of the melted conductor 13 is connected to the electrode 18a (P1) for forming the heat generating body 14 of the insulating member 15 via the other side extending. The shape of the heating element extraction electrode 16 is set such that the area of the electrode 18a (P1) side of the heating element 14 is larger than the area of the connection position with the thin portion 13b of the fusible conductor 13, for example, the connection with the thin portion 13b. The side of the position is an apex, and the side of the electrode 18a (P1) on the extension side is an isosceles triangle formed by the bottom side.

As described above, when the shape of the heating element extraction electrode 16 is an isosceles triangle, as shown in FIG. 2(A), the thin portion 13b of the soluble conductor 13 is superposed on the heating element 14 by heating of the heating element 14. The part begins to melt. Since the molten solder has a property of moving toward a higher wettability in a larger area, the thin portion 13b is brought closer to the direction of the arrow in Fig. 2(B). Further, as shown in FIG. 2(C), the molten solder flows to the wider side of the heat generating body lead-out electrode 16, that is, the bottom side of the isosceles triangle, so that the molten solder can separate the solder faster by the force of the flow. . Thereby, the fusible conductor 13 is separated, and the circuit can be stably blocked.

Further, such an isosceles triangle can be directly formed on the insulating member 15 by using a well-known pattern forming technique. Further, it may be formed by providing an insulating protective layer having an opening having an isosceles triangular shape on the surface of the heat generating body lead electrode 16 having a substantially rectangular shape.

[How to use protective components]

As shown in FIG. 3, the above-described protective element 10 is used for a circuit in a battery pack of a lithium ion secondary battery.

For example, the protective element 10 is incorporated into the battery pack 20 having the battery stack 25 composed of the 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 and discharge control circuit 30 for controlling charge and discharge of the battery stack 25, a protection element 10 of the present invention, which protects the battery stack 25 and the charge and discharge control circuit 30, and a detection circuit 26 for detecting The voltage of each of the battery cells 21 to 24; and the current control element 27 controls the operation of the protection component 10 based on the detection result of the detection circuit 26.

The battery stack 25 is connected in series with battery cells 21 to 24, and the battery cells 21 to 24 are required to protect the overcharge and overdischarge states, and are detachably connected via the positive terminal 20a and the negative terminal 20b of the battery pack 20. The charging device 35 is applied with a charging voltage from the charging device 35. The positive electrode terminal 20a and the negative electrode terminal 20b of the battery pack 20 that is charged by the charging device 35 are connected to an electronic device that is operated by a battery, whereby the electronic device can be operated.

The charge and 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 the current control elements 31 and 32. action. The current control elements 31 and 32 are composed of, for example, field effect transistors (hereinafter referred to as FETs), and the gate voltage is controlled by the control unit 33, thereby controlling the conduction and blocking of the current path of the battery stack 25. The control unit 33 controls the operation of the current control elements 31 and 32 by receiving power supply from the charging device 35 and operating, and when the battery stack 25 is over-discharged or overcharged based on the detection result obtained by the detection circuit 26, Block the current path.

The protection element 10 is connected, for example, to a charge and discharge current path between the battery stack 25 and the charge and discharge control circuit 30, and its operation is controlled by the current control element 27.

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

The current control element 27 is controlled by the detection signal outputted from the detection circuit 26 to cause the protection element 10 to operate when the voltage value of the battery cells 21 to 24 becomes a voltage exceeding a specific overdischarge or overcharge state. The switching operation of the current control elements 31, 32 blocks the charge and discharge current path of the battery stack 25.

In the battery pack 20 constituted by the above configuration, the configuration of the protective element 10 will be specifically described.

First, the protective element 10 to which the present invention is applied has, for example, a circuit configuration as shown in FIG. In other words, the protective element 10 is a circuit composed of a fusible conductor 13 connected in series via the heating element extraction electrode 16 and a heating element 14 that is heated by the connection point of the soluble conductor 13 to fuse the soluble conductor 13 Composition. Further, in the protective element 10, for example, the fusible conductor 13 is connected in series to the charge and discharge current path, and the heat generating body 14 is connected to the current control element 27. One of the two electrodes 12, 12 of the protective element 10 is connected to A1 and the other 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 constructed by such a circuit configuration can achieve low profile, and can reliably fuse the fusible conductor 13 on the current path by the heat generated by the heat generating body 14.

[Modification]

The area of the connection position of the heat generating body lead electrode 16 to the insulating member 15 and the thin portion 13b of the soluble conductor 13 may be any shape as long as it is widened away from the position, but may be the above The isosceles triangle (Fig. 5(A)) and the two sides of the isosceles triangle shown in Fig. 5(B) are curved wedges. Further, as shown in FIG. 5(C) and FIG. 5(D), the connection position of the thin portion 13b of the fusible conductor 13 may be formed to have a wide area on both sides.

On the other hand, the heating element extraction electrode 16 is generally patterned by Cu, Ag (Ag paste, etc.), but the following solder dissolution phenomenon is known: the metal (or the alloy of the main components) is soldered When molten, it dissolves in the molten solder. In the prior protective element having a current capacity of up to about 15 A, the amount of the fusible conductor (solder) is small compared to the amount of metal used for the electrode for the heating element, so that the solder corrosion phenomenon does not need to be considered. Here, as the current of the protective element is increased, if the "thick" solder is used as the fusible conductor 13, there is a problem that the solder is eroded at the time of the action of the protective element 10, and the heater extracts the electrode. When the protection element is activated, the power supplied to the heating element 14 is stopped and the fusing operation is stopped. In order to prevent this, as shown in FIGS. 6(A) and 6(B), a protective film 8 resistant to solder corrosion is formed on the surface of the heating element extraction electrode 16. The meltable conductor 13 is connected via the protective film 8, whereby the solder of the meltable conductor 13 does not erode the heat generating body lead-out electrode 16, and the heat generating body 14 can continuously receive the supply of electric power, so that the fusible conductor 13 can be stably blown. As the protective film 8, any material can be used depending on resistance to solder corrosion, ease of manufacture, etc., but for example, Ni/Au plating is preferably used.

2‧‧‧electrode

3‧‧‧Support members

10‧‧‧Protection components

11‧‧‧Insert substrate

12 (A1), 12 (A2) ‧ ‧ electrodes

13‧‧‧Solid conductor

13a‧‧‧ Thick Wall

13b‧‧‧thin wall

14‧‧‧heating body

15‧‧‧Insulating components

16‧‧‧heating body extraction electrode

18 (P1), 18 (P2) ‧ ‧ heating body electrodes

18a (P1), 18a (P2) ‧ ‧ electrodes

Claims (10)

A protective element comprising: an insulating substrate; a heating element laminated on the insulating substrate; and an insulating member laminated on the insulating substrate so as to cover at least the heating element; first and second electrodes; and a heating element extraction electrode And superposed on the insulating member so as to overlap the heat generating body, and electrically connected to a current path between the first and second electrodes and one of the terminals of the heat generating body, and electrically connected to an external circuit; a fusible conductor connected to the first and second electrodes from the heating element lead-out electrode, and melting a current path between the first electrode and the second electrode by heating; the heating element extracting electrode The device is configured to extend in a direction different from the longitudinal direction of the fusible conductor, and an area of the side of the heating element lead-out electrode extending is larger than an area of a connection position between the heating element extraction electrode and the fusible conductor. According to the protective element of the first aspect of the patent application, the heating element extraction electrode is disposed to extend in a direction perpendicular to the longitudinal direction of the fusible conductor. The heat-generating body lead-out electrode has a triangular shape, and the side of the triangle connected to the fusible conductor is an apex, and the extension side of the heat-generating body lead-out electrode is a bottom side. According to the protective element of claim 3, the heating element extraction electrode extends at a position where the longitudinal direction of the fusible conductor is a line symmetry of the axis of symmetry. For example, in the protection element of claim 1, the heating element extraction electrode is made of Ag or Ag is mainly composed of a metal or Cu or a metal containing Cu as a main component. The heat-generating body extraction electrode has a protective layer on its surface as claimed in claim 5 of the patent application. The protective layer is Ni/Au plating as claimed in claim 6 of the patent application. The protective element according to claim 1, wherein the fusible guiding system is composed of a thick portion and a thin portion which are formed in a concave shape and are thin and flat in a portion where the heating element is overlapped. The protective element of claim 8, wherein the thick portion and the thin portion have substantially the same cross-sectional area. A battery pack comprising: one or more battery cells; a protection element connected to block current flowing through the battery cells; and a current control component that detects respective voltage values of the battery cells and controls heating of the protection components The protective element has: an insulating substrate; a heating element laminated on the insulating substrate; and an insulating member laminated on the insulating substrate so as to cover at least the heating element; first and second electrodes; a body extraction electrode laminated on the insulating member so as to overlap the heating element, electrically connecting a current path between the first and second electrodes and one of the terminals of the heating element, and electrically connected to an external circuit a fusible conductor in which the electrode is led from the heating element to the first and second electrodes Connecting, heating, fuses a current path between the first electrode and the second electrode; the heating element extraction electrode is disposed to extend in a direction different from a longitudinal direction of the soluble conductor, and the heating element leads to an extension side of the electrode The area is larger than the area of the connection position between the heating element extraction electrode and the fusible conductor.