TWI648760B - Protection device and battery pack - Google Patents

Abstract

A protective element according to the present invention includes: a first external electrode; a second external electrode; an insulating substrate disposed between the first external electrode and the second external electrode; and a surface electrode disposed on a surface of the insulating substrate; And a fusible conductor electrically connected to the first external electrode and the second external electrode and supported only by the surface electrode on the surface of the insulating substrate.

Description

Protection component and battery pack

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

Since it is possible to charge, the secondary battery that can be used repeatedly is often supplied to the user in a state of being processed into a battery pack. In particular, in the case of using 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 are embedded in view of overcharge protection and overdischarge protection. Battery. Therefore, the battery pack has a function of blocking the output under a predetermined condition.

Many electronic devices using a lithium ion secondary battery perform an overcharge protection or overdischarge protection operation on the battery pack by using an ON/OF outputted by a FET switch built in the battery pack. However, even if the FET switch is short-circuited for some reason, or if a large current flows due to the application of a lightning surge or the like, or the output voltage is abnormally low due to the life of the battery unit, the output is excessively large. In the case of abnormal voltages, it is also necessary to protect the battery pack and electronic equipment from accidents such as fire. For this reason, even in any abnormal state conceivable as such, in order to safely block the output of the battery unit, a protective element composed of a fuse element having a function of blocking a current path according to a signal from the outside is used.

Protection as a protection circuit for such a lithium ion secondary battery or the like The element is described in Patent Document 1, and a protective element including a heating element is used. In this protective element, the heat generated by the heating element and the fusible conductor that is introduced into the current path are blown.

[Previous Technical Literature] [Patent Literature]

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

However, in order to use a protective element for applications such as mobile phones and notebook computers having a relatively low current capacity, the fusible conductor (fuse) has a current capacity of only about 15 A at the maximum. Since the use of a lithium ion secondary battery has been expanding in recent years, a lithium ion secondary battery has been considered for use in a larger current, and a lithium ion secondary battery has been used for some applications. The use of the high current is, for example, a power tool such as an electric screwdriver, a hybrid vehicle, an electric car, or a power-assisted bicycle. In the use of these large currents, especially at the time of starting, there is a case where a large current exceeding 10A to 100A flows. It is desirable to have a protective element corresponding to such a large current capacity.

Therefore, even in the case of using a large-sized fusible conductor for a large current, it is desirable to provide a protective element and a battery pack capable of securing the insulation resistance after the fuse and also suppressing the deformation of the meltable conductor.

In order to solve the above problems, a protective element according to an embodiment of the present invention includes: a first external electrode; a second external electrode; an insulating substrate disposed between the first external electrode and the second external electrode; and a surface electrode a surface of the insulating substrate; and a fusible conductor electrically connected to the first external electrode and the second external electrode and on the surface of the insulating substrate It is supported only by the surface electrode.

Further, a battery pack according to an embodiment of the present invention includes: one or more batteries a protection element coupled to the one or more battery cells in a manner capable of blocking a current flowing through the one or more battery cells; and a current control component that detects and controls voltage values of the one or more battery cells Current used to heat the protection element. The protective element includes: a first external electrode; a second external electrode; an insulating substrate disposed between the first external electrode and the second external electrode; and a surface electrode disposed on a surface of the insulating substrate and The fuse conductors are electrically connected to the first outer electrode and the second outer electrode, respectively, and are supported only by the surface electrode on the surface of the insulating substrate.

Protective element and battery pack according to an embodiment of the present invention, fusible conductor It is supported only by the surface electrode on the surface of the insulating substrate. In this case, since the degree of freedom in designing the size and arrangement of the surface electrodes is increased, the distance between the first external electrode and the second external electrode can be easily adjusted. Therefore, by sufficiently securing the distance between the surface electrode and the first external electrode, the molten conductor is not easily connected to the first external electrode along the surface of the insulating substrate, so that high insulation resistance can be maintained. Moreover, by sufficiently securing the distance between the surface electrode and the second external electrode, the molten conductor is not easily connected to the second external electrode along the surface of the insulating substrate, so that high insulation resistance can be maintained.

1‧‧‧Protection components

2‧‧‧1st external electrode

3‧‧‧2nd external electrode

4‧‧‧Insert substrate

4a‧‧‧ surface

4b‧‧‧back

5‧‧‧ surface electrode

6‧‧‧fusible conductor

7‧‧‧Connecting materials

10‧‧‧Outer frame

11‧‧‧heating body

12‧‧‧Protection components

13‧‧‧Insulation

15‧‧‧3rd external connection electrode

30‧‧‧Battery Pack

31~34‧‧‧ battery unit

35‧‧‧Battery stack

36‧‧‧Detection circuit

37‧‧‧ Current control components

40‧‧‧Charge and discharge control circuit

41,42‧‧‧ Current control components

43‧‧‧Control Department

45‧‧‧Charging device

50‧‧‧protective components

51‧‧‧Attraction hole

52‧‧‧ Conductive layer

53‧‧‧Back electrode

55‧‧‧Prepared solder

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing a protective element according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing a protective element according to an embodiment of the present invention, showing a state in which the fusible conductor is blown.

Fig. 3 is a cross-sectional view showing a protective element provided with a heat generating body on the surface of an insulating substrate.

Fig. 4 is a cross-sectional view showing a protective element in which a heat generating body is provided on the back surface of an insulating substrate.

Fig. 5 is a cross-sectional view showing a protective element in which a heat generating body is provided inside an insulating substrate.

Fig. 6 is a view showing an example of a circuit configuration of a battery pack to which a protective element according to an embodiment of the present invention is applied.

Fig. 7 is a circuit diagram of a protective element according to an embodiment of the present invention.

Fig. 8 is a cross-sectional view showing a protective element provided with a suction hole on an insulating substrate.

Fig. 9 is a plan view showing a protective element provided with a suction hole on an insulating substrate.

Fig. 10 is a cross-sectional view showing a protective element provided with a suction hole on an insulating substrate, showing a state in which the meltable conductor is blown.

Figure 11 is a cross-sectional view showing a protective element of a comparative example.

Hereinafter, a protective element to which an embodiment of the present invention is applied and a battery pack using the same will be described in detail with reference to the accompanying drawings. 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. Further, since the drawings are schematic views, the ratios of the respective dimensions and the like may be different from the actual ratios. The specific dimensions and the like should be considered and judged according to the following description. Further, of course, there are cases in which the relationship between the dimensions and the ratio are different between the drawings.

[Protection component: agglutination type]

As shown in FIG. 1, the protective element 1 of the embodiment of the present invention includes a first external electrode 2, a second external electrode 3, and a first external electrode 2 and a second external electrode 3. The edge substrate 4 is provided with a surface electrode 5 disposed on the front surface 4a of the insulating substrate 4, and a fusible conductor 6 electrically connected to the first external electrode 2 and electrically connected to the second external electrode 3. Further, in the protective element 1, the soluble conductor 6 is supported only by the surface electrode 5 on the surface 4a of the insulating substrate 4.

In the protective element 1, the first external electrode 2 and the second external electrode 3 are combined with The connection terminals of the external circuit are connected and mounted in the external circuit. Also, since the fusible conductor 6 constitutes a part of the current path of the external circuit, the current path is blocked because the overcurrent soluble conductor 6 corresponding to the rated current is blown (Fig. 2).

The first external electrode 2 and the second external electrode 3 are used to connect the protective element 1 Connection terminal for external circuit. In the inside of the protective element 1, the first external electrode 2 and the second external electrode 3 are connected to the soluble conductor 6 by the connecting material 7 such as solder, and are electrically connected to the soluble conductor 6. The first outer electrode 2 and the second outer electrode 3 are supported by the outer frame 10 and are led out from the inside of the outer frame 10 to the outside. Further, the first outer electrode 2 and the second outer electrode 3 may be disposed on the insulating material close to the insulating substrate 4. The insulating material contains, for example, an epoxy resin or the like.

In the protective element 1, the first outer electrode 2 and the second outer electrode 3 are framed Body 10 supports. Further, the insulating substrate 4 is disposed substantially at the center of the inside of the outer casing 10, and the first outer electrode 2 and the second outer electrode 3 are close to the insulating substrate 4.

The outer frame 10 includes, for example, PPS (polyphenylene sulfide). Any one or two or more kinds of engineering plastics excellent in heat resistance. Further, when the outer frame body 10 is formed into a predetermined shape, it may be molded into the first outer electrode 2 and the second outer electrode 3 by insert molding or the like.

The insulating substrate 4 includes, for example, alumina, glass ceramic, mullite, and zirconia. Any one or two or more of insulating materials. Further, a material for a printed wiring 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.

A surface electrode 5 is formed on the surface 4a of the insulating substrate 4. Surface electrode 5 The connecting material 7 such as solder is connected to the soluble conductor 6, and the soluble conductor 6 is connected to the first external electrode 2 and the second external electrode 3 via a connecting material 7 such as solder. The surface electrode 5 supports the support electrode of the soluble conductor 6 connected to the first external electrode 2 and the second external electrode 3. Further, the surface electrode 5 blocks the current path between the first external electrode 2 and the second external electrode 3. In this case, since the meltable conductor 6 is melted by self-heating corresponding to the overcurrent, the melt-fused conductor 6a (FIG. 10 described later) of the meltable conductor 6 is aggregated.

Further, in order to maintain the insulation resistance after the fusible conductor 6 is blown, the surface electrode 5 is maintained. It is preferable to arrange them so as to be spaced apart from the first external electrode 2 and the second external electrode 3 by a sufficient distance. As shown in FIG. 1 , when the first outer electrode 2 and the second outer electrode 3 face each other inside the outer casing 10 , the surface electrode 5 is disposed substantially at the center of the front surface 4 a of the insulating substrate 4 . For this reason, since the surface electrode 5 holds the molten conductor 6a while being spaced apart from the first external electrode 2 and the second external electrode 3 by a predetermined distance, it is caused by the molten conductor 6a scattered on the surface 4a of the insulating substrate 4. The risk of short circuit will decrease.

Further, in the protective element 1, since the surface 4a of the insulating substrate 4 is not provided Since the side electrode and the fusible conductor 6 are supported only by the surface electrode 5, the degree of freedom in the size and arrangement of the surface electrode 5 becomes high, and the degree of freedom in design considering the risk of short-circuiting after the fusible conductor 6 is melted becomes high. . For this reason, in the protective element 1, since the distance between the surface electrode 5 and the first external electrode 2 can be ensured, and between the surface electrode 5 and the second external electrode 3 can be ensured. Since the distance is long, the molten conductor 6a can be prevented from being connected to the first external electrode 2 and the second external electrode 3 along the surface 4a of the insulating substrate 4, respectively. Therefore, it is possible to maintain a high insulation resistance.

The fusible conductor 6 is melted in an overcurrent state. The fusible conductor 6 contains a meltable Any one or two or more of the conductive materials that are broken. The conductive material is, for example, a SnAgCu-based lead-free solder, a BiPbSn alloy, a BiPb alloy, a BiSn alloy, a SnPb alloy, a PbIn alloy, a ZnAl alloy, an InSn alloy, and a PbAgSn alloy. Further, the fusible conductor 6 may be any one or two or more of the high melting point metals and one or more of the low melting point metals. The high melting point metal is, for example, Ag, Cu, or an alloy containing one or more of these as a main component. The low melting point metal is, for example, solder or a lead-free solder containing Sn as a main component.

Such a fusible conductor 6 is formed on a low melting point metal foil using a plating technique. It is formed by melting a metal layer. Further, the fusible conductor 6 can also be formed using other known lamination techniques and film formation techniques. Further, the fusible conductor 6 may have a high melting point metal layer as an inner layer and a low melting point metal layer as an outer layer. Further, the fusible conductor 6 may have a multilayer structure of four or more layers in which a low-melting-point metal layer and a high-melting-point metal layer are alternately laminated. Thus, the fusible conductor 6 can be formed in various configurations.

Moreover, the fusible conductor 6 does not itself because of the current flowing through the predetermined rated current. It is hot, so it doesn't melt. On the other hand, the fusible conductor 6 melts by self-heating if a current higher than the rated current value flows. Therefore, the current path between the first external electrode 2 and the second external electrode 3 is blocked. At this time, in the fusible conductor 6, since the molten low melting point metal erodes the high melting point metal, the high melting point metal is melted at a temperature lower than the melting temperature. Therefore, the fusible conductor 6 is fused by the low melting point metal to the high melting point metal, and is blown in a short time.

Further, in the fusible conductor 6, the high-melting-point metal layer which becomes the outer layer is laminated The melting temperature of the inner layer of the low melting point metal is much lower than that of the chip fuse composed of the high melting point metal. Therefore, in the fusible conductor 6, the fuse area becomes larger than that of the chip fuse of the same size, and the current rating is greatly improved. Moreover, compared with the chip fuse of the same current rating, it is possible to reduce the size and thickness, and to have excellent rapid meltability.

Further, in the fusible conductor 6, the circuit to which the protective element 1 is mounted is instantaneously applied The phenomenon of an abnormally high voltage, that is, the resistance to surge (pulsation resistance) is improved. That is, the fusible conductor 6 cannot be blown, for example, when a current of 100 A flows for a period of several msec. In this regard, a large current flowing in a very short time flows through the surface layer of the conductor (skin effect). Since the fusible conductor 6 contains a high melting point metal such as Ag plating having a low electric resistance value as an outer layer, a current applied due to a surge easily flows, so that the fusible conductor 6 caused by self-heating can be prevented from being blown. Therefore, in the fusible conductor 6, since the low-melting-point metal is covered with the high-melting-point metal, the resistance to the surge is greatly improved compared to the fuse composed of the solder alloy.

In addition, in the fusible conductor 6, in order to prevent oxidation, and to improve the run-up at the time of fusing A flux (not shown) is applied to wetness or the like.

In the protective element 1 having such a configuration, the fusible conductor 6 is on the insulating substrate 4 The upper surface is supported only by the surface electrode 5. In this case, when the ceramic substrate excellent in thermal shock resistance and thermal conductivity is used as the insulating substrate 4, even if the protective element 1 is repeatedly placed in a high-temperature environment and a low-temperature environment, the fusible conductor 6 is not easy. The deformation due to the difference between the thermal expansion coefficient of the fusible conductor 6 and the thermal expansion coefficient of the insulating substrate 4 is generated, so that the shape and size of the protective element 1 remain stable. For this reason, in the protective element 1, since the resistance value of the fusible conductor 6 is stabilized, the high current rating can be maintained.

[Operation of protection components]

Further, when the protective element 1 flows over a rated overcurrent, in the protective element 1, as shown in Fig. 2, the fusible conductor 6 is melted by self-heating. Therefore, since the meltable conductor 6 is blown to one of the first external electrode 2 side and the second external electrode 3 side, the charge and discharge path of the external circuit is blocked. At this time, in the protective element 1, since the fusible conductor 6 is supported only by the surface electrode 5 on the insulating substrate 4, the degree of freedom in designing the size and arrangement of the surface electrode 5 becomes high, and the first external electrode 2 and The distance between the second external electrodes 3 is easily adjusted. For this reason, in the protective element 1, since the distance between the surface electrode 5 and the first external electrode 2 can be secured, and the distance between the surface electrode 5 and the second external electrode 3 can be secured, the molten conductor 6a becomes difficult. The first external electrode 2 and the second external electrode 3 are connected along the front surface 4a of the insulating substrate 4. Therefore, it is possible to maintain a high insulation resistance.

[The coefficient of thermal expansion of the outer frame and the thermal expansion coefficient of the fusible conductor]

Further, in the protective member 1, the thermal expansion coefficient of the fusible conductor 6 and the thermal expansion coefficient of the outer frame 10 are preferably the same or similar. For example, in the protective element 1, a surface-coated Ag-plated solder foil (thermal expansion coefficient = 22 ppm/° C.) is used as the fusible conductor 6, and a glass fiber-containing PPS resin (thermal expansion coefficient = 20 ppm/° C.) is used as the outer frame body 10. In the case of the present invention, the coefficient of thermal expansion of the fusible conductor 6 is similar to the coefficient of thermal expansion of the outer frame 10. Therefore, even when the protective element 1 is repeatedly placed in a high-temperature environment and a low-temperature environment, deformation between the surface electrode 5 and the first external electrode 2 becomes less likely to accumulate, and between the surface electrode 5 and the second external electrode 3 The deformation becomes difficult to accumulate. Further, it is possible to suppress variations in the resistance value due to deformation or the like of the soluble conductor 6. Therefore, it is possible to maintain a high current rating.

[heating stuff]

Further, in the protective element according to the embodiment of the present invention, as shown in FIG. 3, the heat generating body 11 for blowing the soluble conductor 6 may be provided on the insulating substrate 4. In the following description, the same components as those of the above-described protective element 1 are denoted by the same reference numerals, and detailed description of the components will be omitted.

The protective element 12 provided with the heating element 11 is inserted into the battery pack, for example, because When the overcurrent causes the fusible conductor 6 to generate heat itself, the fusible conductor 6 is blown; and since the overvoltage heating element 11 corresponding to the battery cell is energized and generates heat, the fusible conductor 6 is blown. Therefore, the charge and discharge path of the battery pack is blocked.

The heating element 11 has a relatively high electrical resistance value and is electrically conductive when energized. Any one or two or more of the materials. The conductive material is, for example, W, Mo, Ru, an alloy containing one or more of these as a main component, a composition containing one or more of the above-mentioned main components, and a compound containing one or more of these as a main component. By applying a paste containing a mixture of a powder or the like of these alloys and a resin binder or the like to the surface 4a of the insulating substrate 4 by a screen printing technique, the paste is fired, etc. The heating element 11 is formed.

The heating element 11 is disposed on the surface 4a of the insulating substrate 4 and is provided by the insulating layer 13 Covered. On the insulating layer 13, a surface electrode 5 is disposed. The insulating layer 13 is provided for the purpose of protecting and insulating the heating element 11 and efficiently transferring heat generated by the heating element 11 to the surface electrode 5 and the soluble conductor 6, and is formed, for example, of a glass layer. Since the surface electrode 5 is heated by the heating element 11, the molten material molten conductor 6a of the meltable conductor 6 is easily aggregated.

One end of the heating element 11 is connected to the surface electrode 5, and the heating element 11 is transmitted through the surface. The surface electrode 5 is electrically connected to the fusible conductor 6 disposed on the surface electrode 5. Further, the other end portion of the heating element 11 is connected to a heating element electrode (not shown). The heating body electrode is disposed on the surface 4a of the insulating substrate 4. Further, the heating element electrode is connected to the third external connection electrode 15 (see FIG. 6) disposed on the back surface 4b of the insulating substrate 4, and is connected to the external circuit through the third external connection electrode 15. The protective element 1 is connected to an external circuit, and is incorporated in a power supply path through which the heating element 11 is formed through the third external connection electrode 15 on the circuit board, that is, a power supply path to the heating element 11.

Further, as shown in FIG. 4, in the protective element 12, the heating element 11 may be provided. On the back surface 4b of the insulating substrate 4. The heating element 11 is covered by the insulating layer 13 on the back surface 4b of the insulating substrate 4.

One end of the heating element 11 passes through a heating element electrode (not shown), and a surface electrode 5 and the fusible conductor 6 disposed on the surface electrode 5 are electrically connected. Further, the other end portion of the heating element 11 is connected to the third external connection electrode 15 through a heating element electrode (not shown).

Further, as shown in FIG. 5, in the protective element 12, the heating element 11 may be provided. Inside the insulating substrate 4. In this case, the heating element 11 may not be covered by the insulating layer 13 such as glass. One end of the heating element 11 is transmitted through a heating element electrode (not shown), and is electrically connected to the surface electrode 5 and the fusible conductor 6 disposed on the surface electrode 5. Further, the other end portion of the heating element 11 is connected to the third external connection electrode 15 through a heating element electrode (not shown).

[circuit composition]

As shown in FIG. 6, the protective element 12 is mounted, for example, on a circuit in a battery pack 30 using a lithium ion secondary battery. The battery pack 30 has more than one battery unit, for example, a total of four lithium batteries A battery stack 35 composed of battery cells 31 to 34 of the ion secondary battery.

The battery pack 30 is provided with a battery stack 35, and controls charging and discharging of the battery stack 35. The electric control circuit 40, the protection element 12 for stopping the charging operation when the battery stack 35 is abnormal (the protection element to which the present invention is applied), the detection circuit 36 for detecting the voltage of each of the battery cells 31 to 34, and the detection circuit according to the detection circuit The result of the detection of 36 controls the current control element 37 of the switching element that operates the protection element 12.

In the battery stack 35, it is necessary to perform overcharge protection and overdischarge protection control. The battery cells 31 to 34 are connected in series. The battery stack 35 is detachably connected to the charging device 45 through the positive terminal 30a and the negative terminal 30b of the battery pack 30, and a charging voltage is applied from the charging device 45. The battery pack 30 charged by the charging device 45 is connected to the electronic device driven by the battery through the positive electrode terminal 30a and the negative electrode terminal 30b, and can be driven by the electronic device.

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

The protection element 12 is, for example, introduced between the battery stack 35 and the charge and discharge control circuit 40 The operation of the protection element 12 is controlled by the current control element 37 in the charge and discharge current path.

The detecting circuit 36 is connected to each of the battery cells 31 to 34, and will be in each of the batteries The respective voltage values detected on the cells 31 to 34 are supplied to the control unit 43 of the charge and discharge control circuit 40. Further, when any one of the battery cells 31 to 34 is in an overcharge voltage state or an overdischarge voltage state, the detection circuit 36 outputs a control signal for controlling the current control element 37.

The current control element 37 includes, for example, an FET. The current control element 37 is based on The detection signal output from the detection circuit 36 drives the protection element 12 when the voltage values of the battery cells 31 to 34 become a voltage exceeding a predetermined overdischarge state or an overcharge state. Therefore, the charge and discharge current path of the battery stack 35 is blocked without depending on the switching operation of the current control elements 41, 42.

A protective element 12 for a battery pack 30 having the above composition has the appearance The circuit configuration shown in 7. That is, in the protective element 12, the first external electrode 2 is electrically connected to the battery stack 35, and the second external electrode 3 is electrically connected to the positive electrode terminal 30a. Therefore, the fusible conductor 6 is introduced into the charge and discharge path of the battery stack 35 in series. Further, in the protective element 12, the heating element 11 is connected to the current control element 37 through the heating element electrode and the third external connection electrode 15, and the heating element 11 is connected to the open end of the battery stack 35. Therefore, one end portion of the heat generating body 11 is connected to the open end of one of the fusible conductor 6 and the battery stack 35 through the surface electrode 5. The other end of the heating element 11 is connected to the open end of the other of the current control element 37 and the battery stack 35 through the third external connection electrode 15. Therefore, a power supply path to the heat generating body 11 is formed, and the energization of the heat generating body 11 is controlled by the current control element 37.

[Operation of protection components]

If the battery pack 30 flows over a rated overcurrent, in the protective element 12, since the fusible conductor 6 itself generates heat and melts, the charge and discharge path of the battery pack 30 is blocked.

Moreover, the detection circuit 36 detects the difference of any one of the battery cells 31 to 34. At a normal voltage, an interrupt signal is output to the current control element 37. The current control element 37 controls the current to energize the heating element 11 based on the blocking signal. In the protective element 12, since the current flows from the battery stack 35 through the first external electrode 2, the soluble conductor 6 and the surface electrode 5 to the heating element 11, the heating element 11 starts to generate heat. Therefore, in the protective element 12, if the soluble conductor 6 is heated by the heating element 11, the charge and discharge path of the battery stack 35 is blocked because the soluble conductor 6 is blown.

At this time, even in the case of utilizing an overcurrent, the self-heating of the fusible conductor 6 is melted. In either case of breaking or melting of the fusible conductor 6 that generates heat by the heating element 11 when an overvoltage is applied, in the protective element 12, since the fusible conductor 6 is supported only by the surface electrode 5 on the insulating substrate 4, Therefore, the degree of freedom in designing the size and arrangement of the surface electrode 5 is increased, and the distance between the first external electrode 2 and the second external electrode 3 is easily adjusted. For this reason, in the protective element 12, since the distance between the surface electrode 5 and the first external electrode 2 can be secured, and the distance between the surface electrode 5 and the second external electrode 3 can be secured, the molten conductor 6a becomes difficult. The first external electrode 2 and the second external electrode 3 are connected to the surface 4a of the insulating substrate 4, respectively. Therefore, it is possible to maintain a high insulation resistance.

Further, in the protective element 12, since the fusible conductor 6 contains a high melting point metal and The low melting point metal is fused by the molten low melting point metal to the high melting point metal, and the fusible conductor 6 is blown in a short time.

Further, in the protective member 12, since the fusible conductor 6 is blown, heat is generated. Since the power supply path of the body 11 is also blocked, the heat generation of the heating element 11 is stopped.

The protective element of one embodiment of the present invention is not limited to the use of lithium In the case of a battery pack of an ion secondary battery, it is of course also applicable to various applications in which it is necessary to block a current path in accordance with an electrical signal.

[Protection component: type of attraction]

Further, in the protective element according to the embodiment of the present invention, as shown in FIG. 8, a suction hole 51 for attracting the molten material molten conductor 6a of the meltable conductor 6 may be provided on the insulating substrate 4. In the following description, the same components as those of the above-described protective element 1 are denoted by the same reference numerals, and detailed description of the components will be omitted.

In the protective element 50 provided with the suction hole 51, if the fusible conductor 6 is used When the overcurrent self-heats and melts, or the meltable conductor 6 is melted by the heat generation of the heat generating body 11 with an overvoltage, the molten conductor 6a is attracted to the inside of the suction hole 51 by the capillary phenomenon, so the volume of the molten conductor 6a cut back. In the protective element 50, even in the case where the cross-sectional area of the fusible conductor 6 is increased in order to correspond to a large current application, and the amount of melting is increased, since the molten conductor 6a is attracted by the suction hole 51, the melting The volume of the conductor 6a is reduced.

Therefore, in the protective member 50, the fusible conductor 6 becomes easily melted quickly. Further, in the protective element 50, even if arc discharge occurs when the fusible conductor 6 that generates self-heating due to an overcurrent is generated, the scattering of the molten conductor 6a due to the arc discharge can be reduced. Therefore, it is possible to prevent the insulation resistance from being lowered, and it is possible to prevent a short-circuit failure caused by the molten conductor 6a adhering to the surrounding circuit of the soluble conductor 6.

A conductive layer 52 is provided on the inner wall surface of the suction hole 51. Due to the setting of conductive In the layer 52, the suction hole 51 becomes easy to attract the molten conductor 6a. The conductive layer 52 contains any one or two or more of conductive materials. The conductive material is, for example, copper, silver, gold, iron, nickel, palladium, lead, tin, or an alloy containing one or more of these as a main component. On the inner wall surface of the suction hole 51, a conductive material (for example, conductivity) is formed by a known method such as electrolytic plating or printing. Paste), forming a conductive layer 52.

Further, the suction hole 51 is preferably a through hole extending in the thickness direction of the insulating substrate 4. Therefore, in the suction hole 51, the molten conductor 6a is attracted to the back surface 4b of the insulating substrate 4. Thereby, since more of the molten conductor 6a is attracted, the volume of the molten conductor 6a is further reduced where the fusible conductor 6 is blown. Further, the suction hole 51 may be a non-through hole.

Further, as shown in FIG. 9, the surface electrode 5 is disposed on the surface 4a of the insulating substrate 4 through the insulating layer 13, and the suction hole 51 is provided at a position corresponding to a substantially central portion in the width direction of the surface electrode 5. Further, the number of the suction holes 51 may be one or plural. In the case where the number of the suction holes 51 is plural, since the path for attracting the molten conductor 6a is increased, more of the molten conductors 6a are attracted by the suction holes 51. Therefore, where the fusible conductor 6 is blown, the volume of the molten conductor 6a is further reduced. Here, the plurality of suction holes 51 are arranged, for example, in a straight line, that is, in a row.

Further, the conductive layer 52 provided on the inner wall surface of the suction hole 51 is connected to the surface electrode 5. The surface of the conductive layer 52 and the surface of the surface electrode 5 are preferably in the same plane. The conductive layer 52 and the surface electrode 5 may be integrated. Therefore, in the protective member 50, the molten conductor 6a agglomerated on the surface electrode 5 becomes easy to wet and diffuse on the surface of the surface electrode 5 and the surface of the conductive layer 52, and the molten conductor 6a is easily guided through the conductive layer 52. To the inside of the suction hole 51.

Further, the back surface electrode 53 is disposed on the back surface 4b of the insulating substrate 4 so as to be connected to the conductive layer 52 provided on the inner wall surface of the suction hole 51. As shown in FIG. 10, the back surface electrode 53 is connected to the conductive layer 52. The surface of the conductive layer 52 and the surface of the back surface electrode 53 are preferably in the same plane. The back surface electrode 53 and the conductive layer 52 may be integrated. When the soluble conductor 6 is melted, the molten conductor 6a that has moved from the surface 4a of the insulating substrate 4 to the back surface 4b via the suction hole 51 is on the back surface electrode 53. Agglutination. Therefore, in the protective element 50, the molten conductor 6a aggregated on the back surface electrode 53 is easily wetted and diffused on the surface of the back surface electrode 53 and the surface of the conductive layer 52. Further, since more of the molten conductor 6a is attracted by the suction hole 51, the volume of the molten conductor 6a is further reduced where the soluble conductor 6 is blown.

Further, in the protective element 50, the heating element 11 may not be provided, and only the companion The fusible conductor 6 is blown by the self-heating of the overcurrent, and the heating element 11 may be disposed, and the fusible conductor 6 may be blown by the self-heating accompanying the overcurrent and the heat generated by the heating element 11 accompanying the overvoltage. Further, in the protective element 50, the heat generating body 11 may be disposed on the front surface 4a of the insulating substrate 4, or may be disposed on the back surface 4b of the insulating substrate 4, or may be disposed inside the insulating substrate 4.

In the case where the heating element 11 is provided on the back surface 4b of the insulating substrate 4, the heating element One end portion of the eleven portion is connected to the back surface electrode 53, integrated with the back surface electrode 53, and the conductive layer 52 and the surface electrode 5 are electrically connected to the soluble conductor 6. Further, the other end portion of the heating element 11 is connected to the third external connection electrode 15 through a heating element electrode (not shown). Similarly, when the heating element 11 is provided inside the insulating substrate 4, one end portion of the heating element 11 is electrically connected to the soluble conductor 6 through the surface electrode 5, and the other end portion of the heating element 11 and the third external connection electrode 15 are connected. connection.

When the heating element 11 is disposed on the back surface 4b of the insulating substrate 4, in the protective element 50, since the back surface electrode 53 is heated by the heating element 11, more of the molten conductor 6a is likely to aggregate. Therefore, in the protective element 50, since the action of sucking the molten conductor 6a from the surface electrode 5 through the conductive layer 52 to the back surface electrode 53 can be promoted, the meltable conductor 6 is easily melted.

Further, when the heating element 11 is disposed inside the insulating substrate 4, the surface electrode 5 and the back surface electrode 53 are heated by the heating element 11 through the conductive layer 52 in the protective element 50, so that more of the molten conductor 6a is likely to aggregate. Therefore, in the protective member 50, since the melting can be promoted Since the conductor 6a is attracted to the back surface electrode 53 from the surface electrode 5 through the conductive layer 52, the meltable conductor 6 is easily melted.

Further, the heating element 11 is disposed on the surface 4a of the insulating substrate 4, and the heating element 11 In any case where the back surface 4b of the insulating substrate 4 and the heat generating body 11 are disposed inside the insulating substrate 4, the heat generating body 11 is preferably disposed on both sides of the suction hole 51. Since the surface electrode 5 and the back surface electrode 53 are heated, more of the molten conductors 6a are aggregated and are attracted by the suction holes 51.

Moreover, in the protective element 50, it is also possible to fill and fill the inside of the suction hole 51. The material of the fusible conductor 6 is the same or similar material, the preliminary solder 55 having a lower melting point than the material forming the fusible conductor 6, the flux, and the like. In the protective element 50, when the heating element 11 generates heat, the temperature of the conductive layer 52, the surface electrode 5, and the back surface electrode 53 which are excellent in thermal conductivity is higher than the temperature of the insulating substrate 4. Thereby, since the preliminary solder 55 or the like is melted earlier than the soluble conductor 6, the molten conductor 6a is attracted by the suction hole 51. Therefore, since the molten conductor 6a moves from the front surface 4a of the insulating substrate 4 to the back surface 4b, the current path between the first external electrode 2 and the second external electrode 3 is easily blocked regardless of the orientation of the protective element 50.

[Gap between the first external electrode and the insulating substrate, and a gap between the second external electrode and the insulating substrate]

Further, in the protective elements 1, 12, 50, since a gap is provided between the first external electrode 2 and the insulating substrate 4 supported by the outer frame 10, the first outer electrode 2 and the insulating substrate 4 are preferable. Separated from each other. Further, since a gap is provided between the second external electrode 3 supported by the outer casing 10 and the insulating substrate 4, it is preferable that the second outer electrode 3 and the insulating substrate 4 are spaced apart from each other. If these gaps are provided, the thermal expansion coefficient due to the insulating substrate 4 and the thermal expansion of the outer frame 10 are caused. The deformation of the difference in the expansion coefficient is absorbed, so that the damage of the protective elements 1, 12, 50 can be prevented. Further, in the protective elements 12 and 50, when a gap is provided, the heat transfer path between the insulating substrate 4 and the first external electrode 2 is blocked, and heat transfer between the insulating substrate 4 and the second external electrode 3 is performed. The path is blocked. For this reason, since heat can be more efficiently transferred from the surface electrode 5 to the fusible conductor 6, the fusible conductor 6 is quickly blown.

Further, a gap is provided between the first external electrode 2 and the insulating substrate 4, and When a gap is provided between the second external electrode 3 and the insulating substrate 4, the first external electrode 2 and the surface electrode 5 are not arranged on the same plane, and the second external electrode 3 and the surface electrode 5 are not arranged on the same plane. Therefore, in the protective element 1, since the molten conductor 6a is hard to be connected to the first external electrode 2 and the second external electrode 3 along the surface 4a of the insulating substrate 4, high insulation resistance can be maintained.

Here, when the protective element of one embodiment of the present invention described above is not used, The resulting problem is as follows.

Protective element as a comparative example of the protective elements 1, 12, 50 of the present invention As shown in FIG. 11, the first external electrode 101, the second external electrode 102, and the insulating substrate 103 disposed between the first external electrode 101 and the second external electrode 102 are disposed on the insulating substrate 103. The surface electrode 104 of the surface, and the fusible conductor 106 supported by the pair of side electrodes 105a and 105b. The first outer electrode 101 and the second outer electrode 102 are supported by the outer frame 110.

The protection element 100 is connected by the first external electrode 101 and the second external electrode 102 Connected to an external circuit, the current path of the external circuit is loaded. Thus, the fusible conductor 106 forms part of the current path described above. If the overcurrent exceeding the rated current flows through the fusible conductor 106, the current path is blocked because the fusible conductor 106 is blown by its own heat.

Further, in the protective element 100, a heat generating body 107 that generates heat in response to energization is provided. On the insulating substrate 103. The heating element 107 contains any one or two or more of high melting point metals such as W, Mo, and Ru, and is covered with an insulating layer 108 such as glass. The surface electrode 104 is electrically connected to one end of the heating element 107, and is disposed on the surface of the insulating layer 108 so as to overlap the heating element 107. Further, the heating element 107 is connected to a heating element electrode (not shown), and is connected to an external circuit through the heating element electrode. Therefore, the energization of the heating element 107 is controlled. In the protective element 100, when the overcurrent state of the battery element is detected, if the overvoltage state of the battery cell is detected, the heat generating body 107 formed of the resistor body flows a current, and the heat generating body 107 is used. The heat and the fusible conductor 106 are blown.

In the protection element 100, in order to respond to a large current, by making the fusible conductor 106 The cross-sectional area is increased to reduce the resistance of the fusible conductor 106. Here, if the cross-sectional area of the meltable conductor 106 is increased in response to a large current, it takes time to melt the meltable conductor 106 by the heat generation of the heat generating body 107, and the amount of melting of the meltable conductor 106 is increased at the time of the fuse. Therefore, it is necessary to make the fusible conductor 106 stably blown. Therefore, in the protective element 100, the side electrodes 105a and 105b are disposed on the surface of the insulating substrate 103 on both sides of the surface electrode 104 so as to be spaced apart from each other. When the fusible conductor 106 is connected to the side electrodes 105a and 105b using solder, if the heat generating body 107 generates heat, the side electrodes 105a and 105b efficiently transfer the heat generated by the heat generating body 107 to the fusible conductor 106. The fusible conductor 106 is quickly heated and blown. When the soluble conductor 106 is melted, the side electrodes 105a and 105b support a part of the melt (melted conductor) of the soluble conductor 106 by wettability so as to be in contact with the surface electrode 104, the first external electrode 101, and the second external portion. The electrodes 102 are spaced apart. Therefore, in the protective element 100, the soluble conductor 106 in which the current path between the first external electrode 101 and the second external electrode 102 is inserted is easily melted.

However, in the protective element 100, because the surface electrode 104 and the pair of side electrodes Since the 105a and 105b are disposed in a limited space on the surface of the insulating substrate 103, the distance between the surface electrode 104 and the pair of side electrodes 105a and 105b becomes small. Therefore, after the fusible conductor 106 is blown, since the molten conductor is easily connected to the first external electrode 101 and the second external electrode 102, there is a possibility that the insulation resistance cannot be ensured.

Moreover, as the insulating substrate 103, the ceramics excellent in thermal shock resistance and thermal conductivity are excellent. The porcelain substrate is suitable for use. In this case, since the difference between the thermal expansion coefficient of the fusible conductor 106 and the thermal expansion coefficient of the insulating substrate 103 is large, if the protective element 100 is repeatedly placed in a high temperature environment and a low temperature environment, the surface electrode 104 and the pair of side electrodes 105a are present. Between 105b, the deformation due to the difference in thermal expansion coefficient is accumulated in the fusible conductor 106. For this reason, there is a danger that it is difficult to maintain the high current rating of the protection element 100 because the resistance value varies. Further, due to the above deformation, the meltable conductor 106 and the side electrodes 105a and 105b may be cracked or peeled. In such a tendency, the more the current rating of the protective element 100 is increased, the larger the meltable conductor 106 is, and the more remarkable it becomes.

[Examples]

Next, an embodiment of the present invention will be described. In the present embodiment, a protective element 1 in which the fusible conductor 6 is supported only by the surface electrode 5 on the insulating substrate 4 is prepared (embodiment: see FIG. 1); and the fusible conductor 106 is provided on the insulating substrate 103 by the surface electrode 104 and the protective element 100 supported by the pair of side electrodes 105a and 105b (Comparative Example: see FIG. 11), the insulation property at the time of current interruption, the melting characteristics by heat generation of the heating elements 11 and 107, and the temperature cycle test were evaluated. Reliability.

In the protective element 1 of the embodiment and the protective element 100 of the comparative example, For the edge substrates 4 and 103, a ceramic substrate (thermal expansion coefficient = 7 ppm/° C.) in which the heating elements 11 and 107 are provided on the back surface is used. Further, as the fusible conductors 6 and 106 electrically connected to the first external electrodes 2, 101 and the second external electrodes 3 and 102, a Sn-Ag-Cu-based metal foil to which an Ag plating treatment (thickness: 6 μm) is applied is used ( Thickness = 0.35 mm, width = 5.4 mm, thermal expansion coefficient = 22 ppm / ° C). The fusible conductors 6, 106 are connected to the first outer electrode 2, 101 and the second outer electrodes 3, 102 by solder. Further, the first outer electrode 2, 101 and the second outer electrodes 3, 102 are supported by the outer frames 10 and 110 made of PPS (thermal expansion coefficient = 20 ppm / ° C).

By energizing the protective element 1 of the embodiment and the protective element 100 of the comparative example under the conditions of 190A and 35V, the fusible conductors 6, 106 are blown by self-heating. The fusing time was 5 seconds in either of the protective element 1 of the embodiment and the protective element 100 of the comparative example. After the fusing, the insulation resistance value between the first external electrode 2, 101 and the second external electrodes 3 and 102 was measured, and it was confirmed whether or not the insulation resistance of 10 ⁶ Ω or more can be secured. The measurement results are shown in Table 1.

As shown in Table 1, in the protective element 1 of the embodiment, all of the 16 samples ensure an insulation resistance of 10 ⁶ Ω or more. On the other hand, in the protective element 100 of the comparative example, three of the eight samples had an insulation resistance value of less than 10 ⁶ Ω. In the protective element 100 of the comparative example, since the side electrodes 105a and 105b are provided, the positions of the first external electrode 101, the second external electrode 102, the side electrode 105a, the side electrode 105b, and the surface electrode 104 are close to each other, and thus It is considered that a short circuit is likely to occur due to a molten conductor that is scattered during arc discharge. On the other hand, the protective element 6 of the embodiment in which the fusible conductor 6 is supported only by the surface electrode 5 on the insulating substrate 4 is less likely to be short-circuited, and is effective for maintaining high insulation resistance.

Further, in the protective element 1 of the embodiment and the protective element 100 of the comparative example, When the heat-generating bodies 11 and 107 are energized and heated to cause the fusible conductors 6 and 106 to be blown, the fuse time of the protective element 1 of the embodiment and the protective element 100 of the comparative example is 30 W when the applied electric power is 30 W. For about 10 seconds, the blowing time was about 1.5 seconds under the condition that the applied electric power was 90 W. In other words, the protective element 1 of the embodiment in which the side electrodes 105a and 105b are not provided is the same as the protective element 100 of the comparative example including the side electrodes 105a and 105b, and the fusible conductor 6 can be quickly blown in a large driving power range.

Next, by using the protective element 1 of the embodiment and the protective element of the comparative example 100 was subjected to a temperature cycle test to measure the initial on-resistance value and the on-resistance value after the temperature cycle test. The measurement results are shown in Table 2. In the temperature cycle test, the temperature was varied between -40 ° C (30 min) and 100 ° C (30 min), and the cycle number was set to 300 times.

As shown in Table 2, in the protective element 1 of the embodiment, after the temperature cycle test The rate of increase of the resistance value was suppressed to 1.4%. For this reason, in the protection element 100 of the comparative example, the rate of increase of the resistance value after the temperature cycle test was as high as 3.9%.

In the protective element 100 of the comparative example, the fusible conductor 106 is on the insulating substrate 103 The upper portion is fixed by the side electrodes 105a and 105b and the surface electrode 104. In this case, if the temperature cycle test is performed, since the stress is generated by the difference between the thermal expansion coefficient of the insulating substrate 103 and the thermal expansion coefficient of the soluble conductor 106, the soluble conductor 106 is fixed to the insulating substrate 103. The side electrodes 105a, 105b and the surface electrode 104 are deformed. For this reason, since the resistance value fluctuates due to the deformation of the fusible conductor 106, reliability such as maintenance of the current rating and rapid fusibility is lowered.

On the other hand, in the protective element 1 of the embodiment, since the fusible conductor 6 is absolutely Since one of the edge substrates 4 is fixed by the surface electrode 5, the occurrence of the above deformation is suppressed. Further, since the difference between the thermal expansion coefficient of the outer casing 10 supporting the first outer electrode 2 and the second outer electrode 3 and the thermal expansion coefficient of the soluble conductor 6 is small, the first outer electrode 2 and the second outer electrode 3 and the surface are provided. There is almost no deformation between the electrodes 5. Therefore, by using the configuration in which the fusible conductor 6 is supported only by the surface electrode 5 on the insulating substrate 4, it is possible to ensure a high current rating even when the protective element 1 is exposed to various temperature environments. Maintenance and fast-fuse reliability.

This application is a Japanese patent filed at the Japan Patent Office on May 30, 2014. Priority is claimed on the basis of the application Serial No. 2014-112811, the entire contents of which are hereby incorporated by reference.

Any modifications, combinations, sub-combinations and alterations made by those skilled in the art based on the design requirements and other factors should be included in the scope of the additional patent application and its equivalents.

Claims (7)

A protective element comprising: a first external electrode; a second external electrode; an insulating substrate disposed between the first external electrode and the second external electrode; and a surface electrode disposed in the insulating a surface of the substrate; a fusible conductor electrically connected to the first external electrode and the second external electrode, and supported only by the surface electrode on a surface of the insulating substrate; and an outer frame body The first external electrode and the second external electrode are respectively supported. The protective member of claim 1, wherein the outer frame body has a thermal expansion coefficient identical to a thermal expansion coefficient of the fusible conductor, or has a thermal expansion coefficient similar to a thermal expansion coefficient of the fusible conductor. . The protective element of claim 1, wherein the surface electrode is provided at a substantially central portion of a surface of the insulating substrate. A protective element according to claim 1, comprising a heat generating body disposed on the insulating substrate or inside the insulating substrate. The protective element according to claim 1, wherein the insulating substrate has one or more suction holes in a thickness direction, and the one or more suction holes attract a molten material of the meltable conductor, that is, a molten conductor. The protective element according to claim 1, wherein the first external electrode and the insulating substrate are spaced apart from each other, and the second external electrode and the insulating substrate are spaced apart from each other. A battery pack comprising: one or more battery cells; a protection element coupled to the one or more battery cells in a manner capable of blocking a current flowing through the one or more battery cells; and a current control component Detecting a voltage value of the one or more battery cells and controlling a current for heating the protection element, the protection element including: a first external electrode; a second external electrode; and an insulating substrate disposed on the first 1 between the external electrode and the second external electrode; a surface electrode disposed on a surface of the insulating substrate; and a fusible conductor electrically connected to the first external electrode and the second external electrode, respectively And supporting only the surface electrode on the surface of the insulating substrate; and an outer frame supporting the first external electrode and the second external electrode, respectively.