KR102391555B1 - Protective element and battery pack - Google Patents

Abstract

The protection element includes a first external electrode, a second external electrode, an insulating substrate disposed between the first external electrode and the second external electrode, a surface electrode disposed on the surface of the insulating substrate, a first external electrode, and A soluble conductor electrically connected to each of the second external electrodes and supported only by the surface electrodes on the surface of the insulating substrate is provided.

Description

PROTECTIVE ELEMENT AND BATTERY PACK

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

Most of the secondary batteries that can be repeatedly used because they are rechargeable are provided to the user in a state of being processed into a battery pack. In particular, when a lithium ion secondary battery having a high weight energy density is used, in order to ensure the safety of users and electronic devices, in general, several protection circuits are provided in the battery pack from the viewpoint of overcharge protection and overdischarge protection. is built into For this reason, the battery pack has a function of shutting off the output in a predetermined case.

Most electronic devices using a lithium ion secondary battery perform an operation related to overcharge protection or overdischarge protection of the battery pack by turning on/off the output using a FET switch built into the battery pack. However, when the FET switch is short-circuited or destroyed for some reason or a lightning surge is applied, when a large current flows instantaneously, the output voltage is abnormally lowered due to the life of the battery cell, or, conversely, an excessive abnormal voltage is output Even in this case, the battery pack and electronic device must be protected from accidents such as fire. Therefore, in any conceivable abnormal state, in order to safely cut off the output of the battery cell, a protection element composed of a fuse element having a function of blocking a current path according to an external signal is used.

As a protection element mounted in the protection circuit for such a lithium ion secondary battery etc., the protection element provided with a heating element is used as it describes in patent document 1. In this protection element, the soluble conductor introduce|transduced into a current path|route is melt-cut using the heat_generation|fever of a heat generating body.

Japanese Patent Laid-Open No. 2010-3665

By the way, in order to use a protection element for the use with comparatively low electric current capacity, such as a cellular phone and a notebook computer, a soluble conductor (fuse) has a current capacity of about 15 A at most. Since the use of a lithium ion secondary battery is expanding in recent years, adoption of a lithium ion secondary battery for the use of a larger current is examined, and adoption of a lithium ion secondary battery has already been disclosed for some uses. The use of this large current is, for example, electric tools, such as an electric screwdriver, and transport apparatuses, such as a hybrid car, an electric vehicle, and an electric assist bicycle. In the use of these large currents, a large current exceeding several tens of A to 100 A may flow, especially at the time of starting or the like. Realization of a protection element corresponding to such a large current capacity is desired.

Therefore, even when a large-sized soluble conductor is used in order to respond to a large current, while ensuring the insulation resistance after fusion cutting, it is desired to provide the protection element and battery pack which can also suppress the deformation|transformation of a soluble conductor.

A protection 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 of the insulating substrate. It is equipped with the surface electrode arrange|positioned, and the soluble conductor electrically connected to each of a 1st external electrode and a 2nd external electrode, and supported only by the surface electrode on the surface of an insulating substrate.

Moreover, the battery pack in one Embodiment of this invention includes one or more battery cells, the protection element connected to the one or more battery cells so that the electric current which flows through the one or more battery cells may be interrupted|blocked, and the A current control element is provided that detects each voltage value of one or more battery cells and controls a current for heating the protection element. The protection element includes a first external electrode, a second external electrode, an insulating substrate disposed between the first external electrode and the second external electrode, a surface electrode disposed on the surface of the insulating substrate, and a first external device. A soluble conductor supported only by the surface electrode on the surface of the insulating substrate while being electrically connected to each of the electrode and the second external electrode is provided.

According to the protection element and battery pack in one Embodiment of this invention, a soluble conductor is supported only by the surface electrode on the surface of an insulating substrate. In this case, the distance between the first external electrode and the second external electrode is easily adjusted because the degree of freedom regarding the design of the dimensions and arrangement of the surface electrodes is increased. Therefore, by ensuring a sufficient distance between the surface electrode and the first external electrode, it becomes difficult for the molten conductor to travel on the surface of the insulating substrate and connect with the first external electrode, so that a high insulation resistance can be maintained. In addition, by ensuring a sufficient distance between the surface electrode and the second external electrode, it becomes difficult for the molten conductor to travel on the surface of the insulating substrate and connect to the second external electrode, so that a high insulation resistance can be maintained.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the protection element of one Embodiment of this invention.
It is sectional drawing which shows the protection element of one Embodiment of this invention, and has shown the state after melting of a soluble conductor.
3 : is sectional drawing which shows the protection element in which the heat generating body was formed in the surface of an insulated substrate.
4 : is sectional drawing which shows the protection element in which the heat generating body was formed in the back surface of an insulated substrate.
5 : is sectional drawing which shows the protection element in which the heat generating body was formed inside the insulated substrate.
It is a figure which shows an example of the circuit structure of the battery pack to which the protection element of one Embodiment of this invention was applied.
7 : is a circuit diagram of the protection element in one Embodiment of this invention.
8 : is sectional drawing which shows the protection element in which the suction hole was formed in the insulated substrate.
It is a top view which shows the protection element in which the suction hole was formed in the insulated substrate.
It is sectional drawing which shows the protection element in which the suction hole was formed in the insulating substrate, and has shown the state after melting of a soluble conductor.
11 : is sectional drawing which shows the protection element of a comparative example.

EMBODIMENT OF THE INVENTION Hereinafter, the protection element of one Embodiment to which this invention was applied, and the battery pack using the protection element are demonstrated in detail, referring drawings. In addition, this invention is not limited only to the following embodiment, It goes without saying that various changes are possible within the range which does not deviate from the summary of this invention. In addition, since a drawing is a schematic drawing, the ratio of each dimension, etc. may differ from the actual ratio etc. in some cases. Specific dimensions and the like should be judged in consideration of the following description. Moreover, it goes without saying that there are cases where the dimensions and ratios of the drawings are also different from each other.

[protection element: aggregation type]

As shown in FIG. 1 , a protection element 1 according to an embodiment of the present invention includes a first external electrode 2 , a second external electrode 3 , a first external electrode 2 , and a second external electrode. An insulating substrate 4 disposed between the electrodes 3, a surface electrode 5 disposed and formed on a surface 4a of the insulating substrate 4, and electrically connected to the first external electrode 2 and the second A soluble conductor 6 electrically connected to the external electrode 3 is provided. And in the protection element 1, the soluble conductor 6 is supported only by the surface electrode 5 on the surface 4a of the insulated substrate 4.

In the protection element 1, the first external electrode 2 and the second external electrode 3 are connected to the connection terminals of the external circuit, and thereby are attached to the external circuit. Moreover, since the soluble conductor 6 comprises a part of the current path of an external circuit, the current path is interrupted|blocked by the soluble conductor 6 being fused by overcurrent exceeding a rating (FIG. 2).

The first external electrode 2 and the second external electrode 3 are connection terminals for connecting the protection element 1 to an external circuit. Since each of the first external electrode 2 and the second external electrode 3 is connected to the soluble conductor 6 inside the protection element 1 through a connection material 7 such as solder, It is electrically connected through the soluble conductor 6 . The first external electrode 2 and the second external electrode 3 are supported by the outer casing 10 , and are led out from the inside of the outer casing 10 . In addition, the first external electrode 2 and the second external electrode 3 may be disposed on an insulating material adjacent to the insulating substrate 4 . This insulating material contains an epoxy resin etc., for example.

In the protection element 1 , the first external electrode 2 and the second external electrode 3 are supported by the external casing 10 . In addition, the insulating substrate 4 is arranged and formed in the substantially central portion of the outer casing 10 so that the first external electrode 2 and the second external electrode 3 and the insulating substrate 4 are adjacent to each other.

The outer casing 10 contains any one type or two or more types of engineering plastics excellent in heat resistance, such as PPS (Polyphenylenesulfide: Polyphenylenesulfide), for example. Further, when the outer casing 10 is molded to have a predetermined shape, it may be molded to be integral with the first external electrode 2 and the second external electrode 3 using insert molding or the like.

The insulating substrate 4 contains any one type or two or more types of materials which have insulating properties, such as alumina, glass ceramics, mullite, and a zirconia, for example. 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 melting.

A surface electrode 5 is formed on the surface 4a of the insulating substrate 4 . The surface electrode 5 is connected to the soluble conductor 6 through a connection material 7 such as solder, and the soluble conductor 6 is connected to a first external electrode ( 2) and the second external electrode 3, respectively. The surface electrode 5 is a support electrode that supports 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 soluble conductor 6 melts using the self-heating accompanying an overcurrent, the molten conductor 6a (FIG. 10 mentioned later) which is a melt of the soluble conductor 6 aggregates.

In addition, in order to maintain the insulation resistance after melting of the soluble conductor 6, the surface electrode 5 is arrange|positioned so that a sufficient distance from each of the 1st external electrode 2 and the 2nd external electrode 3 may be kept. It is preferable to be As shown in FIG. 1 , when the first external electrode 2 and the second external electrode 3 face each other inside the outer casing 10 , the surface electrode 5 is the It is arrange|positioned and formed in the substantially central part of the surface 4a. Accordingly, the surface electrode 5 holds the molten conductor 6a in a state with a predetermined distance therebetween from each of the first external electrode 2 and the second external electrode 3, so that the insulating substrate The risk of a short circuit resulting from the molten conductor 6a scattered on the surface 4a of (4) is reduced.

Moreover, in the protection element 1, since a side electrode is not arrange|positioned by the surface 4a of the insulated substrate 4, but the soluble conductor 6 is supported only by the surface electrode 5, the surface electrode While the degree of freedom regarding the dimension and arrangement|positioning of (5) becomes high, the degree of freedom of the design which considered the risk of the short circuit after melting of the soluble conductor 6 becomes high. Therefore, in the protection element 1, the distance between the surface electrode 5 and the first external electrode 2 is secured and the distance between the surface electrode 5 and the second external electrode 3 is secured. , the molten conductor 6a rides on the surface 4a of the insulating substrate 4 and is prevented from connecting with each of the first external electrode 2 and the second external electrode 3 . Accordingly, a high insulation resistance is maintained.

The soluble conductor 6 melts in an overcurrent state. This soluble conductor 6 contains any 1 type or 2 or more types among the electroconductive materials which can be cut by melting. Examples of the conductive material include SnAgCu-based Pb-free solder, BiPbSn alloy, BiPb alloy, BiSn alloy, SnPb alloy, PbIn alloy, ZnAl alloy, InSn alloy, and PbAgSn alloy. In addition, any one type or two or more types of high-melting-point metals, and any one type, or two or more types of laminated bodies of the low-melting-point metals may be sufficient as the soluble conductor 6 . The high-melting-point metal is, for example, Ag, Cu, or an alloy containing one or more of them as a main component. The low-melting-point metal is, for example, a solder, a Pb-free solder containing Sn as a main component, or the like.

Such a soluble conductor 6 is formed by forming a high-melting-point metal layer into a film on low-melting-point metal foil using a plating technique. Moreover, the soluble conductor 6 may be formed using another well-known lamination technique and film formation technique. In addition, the soluble conductor 6 makes a high-melting-point metal layer into an inner layer, and is good also considering a low-melting-point metal layer as an outer layer. Moreover, the multilayer structure of 4 or more layers in which the soluble conductor 6 was laminated|stacked alternately with the low-melting-point metal layer and the high-melting-point metal layer may be sufficient as it. Thus, the soluble conductor 6 can be formed so that it may become various structures.

Moreover, since the soluble conductor 6 does not self-heat in the state in which a predetermined|prescribed rated current is flowing, it is not melted. On the other hand, since the soluble conductor 6 self-heats when the electric current of a value higher than a rating flows, it melts. Accordingly, the current path between the first electrode 2 and the second electrode 3 is blocked. At this time, in the soluble conductor 6, since the molten low-melting-point metal erodes a high-melting-point metal, the high-melting-point metal melts at temperature lower than a melting temperature. Therefore, the soluble conductor 6 is fused in a short time using the erosion action of the high-melting-point metal by a low-melting-point metal.

Moreover, in the soluble conductor 6, when the high melting-point metal used as an outer layer is laminated|stacked on the low-melting-point metal used as an inner layer, fusing temperature is significantly reduced rather than the chip fuse etc. which consist of a high-melting-point metal. Therefore, in the soluble conductor 6, compared with the chip fuse of the same size, while a cross-sectional area becomes large, a current rating improves significantly. Moreover, compared with the chip fuse of the same current rating, while size reduction and thickness reduction are attained, it is excellent in rapid melting and breaking property.

Moreover, in the soluble conductor 6, the phenomenon to which an unusually high voltage is applied instantaneously to the electric circuit with which the protection element 1 was attached, tolerance (pulse resistance) with respect to what is called a surge improves. That is, the soluble conductor 6 must not be fused by melting, for example, when an electric current of 100 A flows for several msec. In this regard, a large current flowing in an extremely short time flows through the surface layer of the conductor (skin effect). When the soluble conductor 6 contains a high melting point metal such as Ag plating having a low resistance value as an outer layer, the current applied due to the surge flows easily, so that the melting of the soluble conductor 6 due to self-heating is prevented. . Therefore, in the soluble conductor 6, when a low-melting-point metal is coat|covered with high-melting-point metal, compared with the fuse which consists of a solder alloy, tolerance with respect to a surge improves significantly.

Moreover, the flux (not shown) is apply|coated to the soluble conductor 6 for the improvement of the wettability at the time of oxidation prevention and fusion cutting, etc.

In the protection element 1 which has such a structure, the soluble conductor 6 is supported only by the surface electrode 5 on the insulated substrate 4 . In this case, when a ceramic substrate excellent in thermal shock resistance and thermal conductivity is used as the insulating substrate 4, etc., even when the protection element 1 is repeatedly placed in a high-temperature environment and a low-temperature environment, the soluble conductor ( Since the distortion resulting from the difference of the thermal expansion coefficient of 6) and the thermal expansion coefficient of the insulating substrate 4 becomes difficult to generate|occur|produce in the soluble conductor 6, the external shape and dimension of the protection element 1 are stabilized. Thereby, in the protection element 1, since the resistance value of the soluble conductor 6 is stabilized, a high rating is maintainable.

[Operation of protection element]

Moreover, when the overcurrent exceeding a rating flows through the protection element 1, in the protection element 1, as shown in FIG. 2, the soluble conductor 6 melts using self-heating. As a result, the soluble conductor 6 is cut by melting in either one of the side close to the first external electrode 2 and the side close to the second external electrode 3 , so that the charging/discharging path of the external circuit is interrupted. At this time, in the protection element 1, since the soluble conductor 6 is supported only by the surface electrode 5 on the insulating substrate 4, the freedom degree of the design regarding the dimension and arrangement|positioning of the surface electrode 5. The distance between the first external electrode 2 and the second external electrode 3 is easily adjusted with increasing . Therefore, in the protection element 1, the distance between the surface electrode 5 and the first external electrode 2 is secured and the distance between the surface electrode 5 and the second external electrode 3 is secured. , it becomes difficult for the molten conductor 6a to ride on the surface 4a of the insulating substrate 4 and connect with the first external electrode 2 and the second external electrode 3 . Therefore, high insulation resistance can be maintained.

[Coefficient of thermal expansion of outer casing and coefficient of thermal expansion of fusible conductor]

Moreover, in the protection element 1, it is preferable that the thermal expansion coefficient of the soluble conductor 6 and the thermal expansion coefficient of the outer casing 10 are the same or approximate. For example, in the protection element 1, as the soluble conductor 6, while using the solder foil (coefficient of thermal expansion = 22 ppm/degreeC) by which the surface was plated with Ag, glass fiber containing PPS as the outer casing 10 When resin (coefficient of thermal expansion = 20 ppm/degreeC) is used, the thermal expansion coefficient of the soluble conductor 6 and the thermal expansion coefficient of the outer casing 10 approximate. Accordingly, even when the protection element 1 is repeatedly placed in a high-temperature environment and a low-temperature environment, distortion is less likely to accumulate between the surface electrode 5 and the first external electrode 2, and the surface electrode 5 It becomes difficult for distortion to accumulate between and the second external electrode 3 . Moreover, the fluctuation|variation of the resistance value resulting from the deformation|transformation of the soluble conductor 6, etc. is suppressed. Therefore, the fixed rating can be maintained.

[Heating element]

Moreover, in the protection element of one Embodiment of this invention, as shown in FIG. 3, the heat generating body 11 for cutting the soluble conductor 6 by melting in the insulating substrate 4 may be formed. In addition, in the following description, while attaching|subjecting the same code|symbol about the component same as the component of the protection element 1 mentioned above, the detailed description about the component is abbreviate|omitted.

When the protection element 12 provided with the heating element 11 is attached to a battery pack, for example, since the soluble conductor 6 self-heats at the time of an overcurrent, in addition to the soluble conductor 6 being fused, In order to generate heat while the heat generating element 11 is energized according to the overvoltage of the battery cell, the soluble conductor 6 is fused. Accordingly, the charging/discharging path of the battery pack is blocked.

The heat generating element 11 contains any one type or two or more types of materials which have a comparatively high resistance value and the electrically conductive material which generate|occur|produces when electricity is supplied. The material having this conductivity 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 these as a main component, and a compound containing one or more of these as a main component. A paste containing a mixture of powders such as these alloys and a resin binder is applied to the surface 4a of the insulating substrate 4 in a predetermined pattern using a screen printing technique, and then the paste is fired, etc. , the heating element 11 is formed.

The heat generating body 11 is coat|covered with the insulating layer 13 while arrange|positioning and forming in the surface 4a of the insulating substrate 4 . On the insulating layer 13, the surface electrode 5 is arrange|positioned. The insulating layer 13 is formed in order to efficiently transmit the heat|fever generated in the heat generating body 11 to the surface electrode 5 and the soluble conductor 6 while aiming at protection and insulation of the heat generating body 11, For example, it consists of a glass layer. The surface electrode 5 makes it easy to aggregate the molten conductor 6a which is a melt of the soluble conductor 6 by being heated by the heat generating body 11.

One end of the heat generating body 11 is connected to the surface electrode 5, and the heat generating body 11 is electrically connected to the soluble conductor 6 disposed on the surface electrode 5 via the surface electrode 5. is connected to Moreover, the other end of the heat generating body 11 is connected to the heat generating body electrode which is not shown in figure. The heat generating electrode is arranged and formed on the surface 4a of the insulating substrate 4 . Further, the heating element electrode is connected to a third external connection electrode 15 (see FIG. 6 ) disposed and formed on the back surface 4b of the insulating substrate 4, and an external circuit is passed through the third external connection electrode 15 . is connected with The protection element 1 is connected to the external circuit, so that it is attached to the power supply path in which the heating element 11 is formed via the third external connection electrode 15 on the circuit board, that is, the power supply path to the heating element 11 .

Moreover, as shown in FIG. 4, in the protection element 12, the heat generating body 11 may be arrange|positioned on the back surface 4b of the insulated substrate 4, and may be formed. The heat generating element 11 is covered with the insulating layer 13 on the back surface 4b of the insulating substrate 4 .

One end of the heat generating body 11 is electrically connected to the surface electrode 5 and the soluble conductor 6 arranged and formed on the surface electrode 5 via a heat generating body electrode (not shown). In addition, the other end of the heat generating element 11 is connected to the third external connection electrode 15 via a heat generating electrode not shown.

Moreover, as shown in FIG. 5, in the protection element 12, the heat generating body 11 may be arrange|positioned inside the insulated substrate 4, and may be formed. In this case, the heat generating element 11 does not need to be coat|covered with the insulating layer 13, such as glass. One end of the heat generating body 11 is electrically connected to the surface electrode 5 and the soluble conductor 6 arranged and formed on the surface electrode 5 via a heat generating body electrode (not shown). In addition, the other end of the heat generating element 11 is connected to the third external connection electrode 15 via a heat generating electrode not shown.

[Circuit configuration]

As shown in FIG. 6, such a protection element 12 is attached to the circuit in the battery pack 30 using a lithium ion secondary battery, for example. The battery pack 30 is provided with the battery stack 35 which consists of one or more battery cells, for example, battery cells 31-34 which are a total of four lithium ion secondary batteries.

The battery pack 30 includes a battery stack 35 , a charge/discharge control circuit 40 for controlling charging and discharging of the battery stack 35 , and a protection element for stopping a charging operation when the battery stack 35 is abnormal. 12) (the protection element to which the present invention is applied), the detection circuit 36 for detecting the voltage of each battery cell 31 to 34, and the operation of the protection element 12 according to the detection result of the detection circuit 36 A current control element 37 which is a switch element for controlling is provided.

In the battery stack 35, the battery cells 31 to 34 that require control for protection from an overcharge state and an overdischarge state are connected in series. This battery stack 35 is detachably connected to the charging device 45 via the positive electrode terminal 30a and the negative electrode terminal 30b of the battery pack 30, and the charging voltage from the charging device 45 is is authorized The battery pack 30 charged by the charging device 45 can operate the electronic device by being connected to the electronic device which operates using the battery via the positive electrode terminal 30a and the negative electrode terminal 30b.

The charge/discharge control circuit 40 includes two current control elements 41 and 42 introduced in series into a current path from the battery stack 35 to the charging device 45 , and the current control elements 41 and 42 . A control unit 43 for controlling the operation is provided. The current control elements 41 and 42 include, for example, field effect transistors (hereinafter referred to as FETs). The current control elements 41 , 42 control the state (conduction and cutoff) of the current path of the battery stack 35 by controlling the gate voltage by the control unit 43 . The control unit 43 operates by receiving power supply from the charging device 45 , and according to the detection result by the detection circuit 36 , when the battery stack 35 is in an over-discharge state or an over-charge state, a current path Controls the operation of the current control elements 41 and 42 so that .

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

The detection circuit 36 is connected with each battery cell 31-34, and transmits each voltage value detected in each battery cell 31-34 to the control part 43 of the charge/discharge control circuit 40. supply Moreover, the detection circuit 36 outputs the control signal for controlling the current control element 37, when any one of the battery cells 31-34 becomes an overcharge voltage state or an overdischarge voltage state.

The current control element 37 includes, for example, an FET. This current control element 37 protects when, according to the detection signal output from the detection circuit 36, the voltage value of the battery cells 31 to 34 becomes a voltage exceeding a predetermined overdischarge state or overcharge state. The element 12 is operated. Accordingly, the charging/discharging current path of the battery stack 35 is cut off regardless of the switch operation of the current control elements 41 and 42 .

The protection element 12 used for the battery pack 30 which has the above structures has a circuit structure as shown in FIG. That is, in the protection 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. . Thereby, the soluble conductor 6 is introduced into the charge/discharge path|route of the battery stack 35 in series. Further, in the protection element 12 , the heating element 11 is connected to the current control element 37 via the heating element electrode and the third external connection electrode 15 , and the heating element 11 is connected to the battery stack 35 ) is connected to the open end of Thereby, the one end of the heat generating body 11 is connected with the one open end of the soluble conductor 6 and the battery stack 35 via the surface electrode 5. As shown in FIG. The other end of the heat generating element 11 is connected to the other open end of the current control element 37 and the battery stack 35 via the third external connection electrode 15 . Thereby, while the electric power supply path|route to the heat generating element 11 is formed, electricity supply to the heat generating element 11 is controlled by the current control element 37. As shown in FIG.

[Operation of protection element]

Since the soluble conductor 6 melts with self-heating in the protection element 12 when the overcurrent exceeding a rating flows through the battery pack 30, the charging/discharging path|route of the battery pack 30 is interrupted|blocked.

In addition, the detection circuit 36 outputs a cutoff signal to the current control element 37 when an abnormal voltage of any of the battery cells 31 to 34 is detected. This current control element 37 controls the current so that the heating element 11 is energized according to the cut-off signal. In the protection element 12, since an electric current flows from the battery stack 35 to the heat generating element 11 through the 1st external electrode 2, the soluble conductor 6, and the surface electrode 5, the heat generating element 11 starts to exotherm. Thereby, in the protection element 12, when the soluble conductor 6 is heated by the heat generating body 11, since the soluble conductor 6 is fusion-cut, the charge/discharge path|route of the battery stack 35 is interrupted|blocked.

At this time, in any of the melting of the soluble conductor 6 using the self-heating at the time of an overcurrent, and the melting|fusing of the soluble conductor 6 using the heat_generation|fever of the heat generating body 11 at the time of an overvoltage, the protection element 12 Since the soluble conductor 6 is supported only by the surface electrode 5 on the insulated substrate 4, while the freedom degree of the design regarding the dimension and arrangement|positioning of the surface electrode 5 increases, 1st exterior The distance between the electrode 2 and the second external electrode 3 is easily adjusted. Accordingly, in the protection element 12 , the distance between the surface electrode 5 and the first external electrode 2 is secured and the distance between the surface electrode 5 and the second external electrode 3 is secured. , it becomes difficult for the molten conductor 6a to ride along the surface 4a of the insulating substrate 4 and to be connected to each of the first external electrode 2 and the second external electrode 3 . Therefore, high insulation resistance can be maintained.

Moreover, in the protection element 12, when the soluble conductor 6 contains a high-melting-point metal and a low-melting-point metal, the soluble conductor 6 utilizes the erosion action of the high-melting-point metal by the molten low-melting-point metal. melted in a short time

Moreover, in the protection element 12, when the soluble conductor 6 is melt-cut, since the electric power supply path|route to the heat generating body 11 is also interrupted|blocked, heat_generation|fever of the heat generating body 11 is stopped.

The protection element of one embodiment of the present invention is not limited to a case where it is applied to a battery pack using a lithium ion secondary battery, and of course it is applicable to various uses requiring blocking of a current path according to an electrical signal.

[a protection element: a suction type]

Moreover, in the protection element of one Embodiment of this invention, as shown in FIG. 8, the suction hole 51 for attracting the molten conductor 6a which is a melt|fusion of the soluble conductor 6 to the insulated substrate 4 is may be formed. In addition, in the following description, while attaching|subjecting the same code|symbol about the component same as the component of the protection element 1 mentioned above, the detailed description about the component is abbreviate|omitted.

In the protection element 50 in which the suction hole 51 was formed, the soluble conductor 6 melts using the self-heating accompanying an overcurrent, or using the heat_generation|fever of the heat generating body 11 accompanying an overvoltage, the soluble conductor 6 ) melts, the volume of the molten conductor 6a decreases because the molten conductor 6a is attracted to the inside of the suction hole 51 using the capillary phenomenon. In the protection element 50, since the molten conductor 6a is attracted|sucked by the suction hole 51 by increasing the cross-sectional area of the soluble conductor 6 in order to respond|correspond to a large current use, even when a molten amount increases, the molten conductor The volume of (6a) decreases.

Thereby, in the protection element 50, the soluble conductor 6 becomes easy to cut by melting quickly. Moreover, in the protection element 50, even if an arc discharge generate|occur|produces at the time of melting of the soluble conductor 6 using the self-heating accompanying an overcurrent, the scattering of the molten conductor 6a resulting from the arc discharge is reduced. Thereby, while the fall of insulation resistance is prevented, the short circuit failure resulting from the molten conductor 6a adhering to the circuit around the soluble conductor 6 is prevented.

A conductive layer 52 is formed on the inner wall surface of the suction hole 51 . When the conductive layer 52 is formed, the suction hole 51 easily attracts the molten conductor 6a. The conductive layer 52 contains any one type or two or more types of electroconductive materials. The conductive material is copper, silver, gold, iron, nickel, palladium, lead, tin, or an alloy containing at least one of them as a main component. The conductive layer 52 is formed on the inner wall surface of the suction hole 51 by forming a conductive material (eg, conductive paste) into a film using a known method such as an electrolytic plating method and a printing method.

Moreover, it is preferable that the suction hole 51 is a through-hole extended in the thickness direction of the insulated substrate 4 . Thereby, in the suction hole 51, it attract|sucks until the molten conductor 6a reaches the back surface 4b of the insulated substrate 4. Thereby, since more molten conductor 6a is attracted|sucked, the volume of the molten conductor 6a reduces more in the place where the soluble conductor 6 was cut by fusion. In addition, the suction hole 51 may be a non-penetrating hole.

Moreover, as shown in FIG. 9, the surface electrode 5 is arrange|positioned on the surface 4a of the insulated substrate 4 through the insulating layer 13, and the suction hole 51 is the surface electrode 5 ) is formed at a position corresponding to a substantially central portion in the width direction. In addition, one may be sufficient as the number of the suction holes 51, and several may be sufficient as it. Since the path|route which attracts the molten conductor 6a increases when the number of the suction holes 51 is plural, more molten conductor 6a is attract|sucked by the suction hole 51. As shown in FIG. Thereby, the place where the soluble conductor 6 was cut by melting WHEREIN: The volume of the molten conductor 6a reduces more. Here, the some suction hole 51 is arrange|positioned so that it may line up in a line, ie, linear, for example.

In addition, the conductive layer 52 formed on the inner wall surface of the suction hole 51 is connected to the surface electrode 5 . It is preferable that the surface of the conductive layer 52 and the surface of the surface electrode 5 exist in the same plane. The conductive layer 52 and the surface electrode 5 may be integrated. Thereby, in the protection element 50, while the molten conductor 6a aggregated on the surface electrode 5 gets wet on the surface of the surface electrode 5 and the surface of the conductive layer 52, and spreads easily, the fusion The conductor 6a is easily guided to the inside of the suction hole 51 through the conductive layer 52 .

Moreover, the back surface electrode 53 is arrange|positioned on the back surface 4b of the insulating substrate 4 so that it may connect with the conductive layer 52 formed in the inner wall surface of the suction hole 51. As shown in FIG. As shown in FIG. 10 , the back electrode 53 is connected to the conductive layer 52 . It is preferable that the surface of the conductive layer 52 and the surface of the back electrode 53 exist in the same plane. The back electrode 53 and the conductive layer 52 may be integrated. When the soluble conductor 6 melts, the molten conductor 6a which moved from the surface 4a of the insulated substrate 4 to the back surface 4b via the suction hole 51 will aggregate on the back electrode 53. Thereby, in the protection element 50, the molten conductor 6a aggregated on the back electrode 53 wets the surface of the back electrode 53 and the surface of the conductive layer 52, and it becomes easy to spread. Moreover, since more molten conductor 6a is attract|sucked by the suction hole 51, the volume of the molten conductor 6a reduces more in the place where the soluble conductor 6 was cut by fusion.

In addition, in the protection element 50, the heat generating body 11 is not arrange|positioned, but the soluble conductor 6 may be melt-cut using only the self-heating accompanying an overcurrent, and the heat generating body 11 is arrange|positioned and accompanied with an overcurrent. In addition to the self-heating to be carried out, you may cut the soluble conductor 6 by melting using the heat generation of the heat generating body 11 accompanying an overvoltage. Moreover, in the protection element 50, the heat generating body 11 may be arrange|positioned on the front surface 4a of the insulated substrate 4, and the heat generating body 11 may be arrange|positioned and formed in the back surface 4b of the insulated substrate 4, , the heating element 11 may be disposed inside the insulating substrate 4 .

When the heating element 11 is formed on the back surface 4b of the insulating substrate 4, one end of the heating element 11 is connected to the back electrode 53, and is integrated with the back electrode 53, and a conductive layer ( 52 ) and the surface electrode 5 are electrically connected to the soluble conductor 6 . Further, the other end of the heating element 11 is connected to the third external connection electrode 15 via a heating element electrode (not shown). Similarly, when the heat generating body 11 is formed inside the insulated substrate 4, one end of the heat generating body 11 is electrically connected to the soluble conductor 6 through the surface electrode 5, and the heat generating body 11 The other end of the is connected to the third external connection electrode (15).

When the heating element 11 is disposed on the back surface 4b of the insulating substrate 4, in the protection element 50, the back electrode 53 is heated by the heating element 11, so more molten conductors 6a ) becomes easy to aggregate. Therefore, in the protection element 50, the soluble conductor 6 is easy to cut by melting by accelerating the effect|action by which the molten conductor 6a is attracted|sucked from the surface electrode 5 through the conductive layer 52 to the back electrode 53. lose

Moreover, if the heat generating body 11 is arrange|positioned inside the insulating substrate 4, in the protection element 50, the surface electrode 5 and the back electrode 53 are the heat generating body 11 via the conductive layer 52. By heating by , it becomes easy to aggregate more molten conductor 6a. Therefore, in the protection element 50, the soluble conductor 6 is easy to cut by melting by accelerating the effect|action by which the molten conductor 6a is attracted|sucked from the surface electrode 5 through the conductive layer 52 to the back electrode 53. lose

In addition, when the heating element 11 is arranged and formed on the front surface 4a of the insulating substrate 4, when the heating element 11 is arranged and formed on the back surface 4b of the insulating substrate 4, the heating element 11 is insulated In any case of arrangement|positioning formation inside the board|substrate 4, it is preferable that the heat generating body 11 is arrange|positioned on both sides of the suction hole 51. As shown in FIG. This is because, since the front electrode 5 and the back electrode 53 are heated, more molten conductors 6a are aggregated and are attracted by the suction hole 51 .

Moreover, in the protection element 50, in the inside of the suction hole 51, melting|fusing point is lower than the forming material of the material of the same or similar to the forming material of the soluble conductor 6, or the soluble conductor 6 preliminary solder 55. Alternatively, a flux or the like may be charged. In the protection element 50, when the heat generating body 11 heats up, the temperature of the conductive layer 52 excellent in heat conduction, the front electrode 5, and the back electrode 53 becomes higher than the temperature of the insulating substrate 4 earlier. . Thereby, since the preliminary|backup solder 55 etc. melt|dissolve before the soluble conductor 6, the molten conductor 6a is drawn into the suction hole 51. As shown in FIG. Therefore, since the molten conductor 6a moves from the front surface 4a to the back surface 4b of the insulating substrate 4, regardless of the direction of the protection element 50, the first external electrode 2 and the second The current path between the external electrodes 3 is likely to be blocked.

[Clearance between the first external electrode and the insulating substrate and the clearance between the second external electrode and the insulating substrate]

Further, in the protection elements 1, 12, 50, since a clearance is formed between the first external electrode 2 supported by the external casing 10 and the insulating substrate 4, the first external electrode ( It is preferable that 2) and the insulating substrate 4 are mutually spaced apart. Further, since a clearance is formed between the second external electrode 3 supported by the external casing 10 and the insulating substrate 4, the second external electrode 3 and the insulating substrate 4 are spaced apart from each other. It is preferable to be When these clearances are formed, since distortion resulting from the difference between the coefficient of thermal expansion of the insulating substrate 4 and the coefficient of thermal expansion of the outer casing 10 is absorbed, damage to the protection elements 1, 12, 50 is prevented. do. Further, in the protection elements 12 and 50, if a clearance is formed, the thermal path between the insulating substrate 4 and the first external electrode 2 is blocked, and the insulating substrate 4 and the second external electrode ( 3) The thermal path between them is blocked. Thereby, since heat is transmitted from the surface electrode 5 to the soluble conductor 6 more efficiently, the soluble conductor 6 is cut by melting quickly.

Further, when a clearance is formed between the first external electrode 2 and the insulating substrate 4 and a clearance is formed between the second external electrode 3 and the insulating substrate 4, the first external electrode (2) and the surface electrode 5 do not line up on the same plane, and the 2nd external electrode 3 and the surface electrode 5 do not line up on the same plane. Accordingly, in the protection element 1, the molten conductor 6a rides on the surface 4a of the insulating substrate 4, and it becomes difficult to connect with the first external electrode 2 and the second external electrode 3, High insulation resistance can be maintained.

Here, the problems in the case of not using the protection element of one Embodiment of this invention mentioned above are as follows.

The protection element 100 of the comparative example with respect to the protection element 1, 12, 50 of this invention, as shown in FIG. 11, the 1st external electrode 101, the 2nd external electrode 102, and the 1st An insulating substrate 103 disposed between the external electrode 101 and the second external electrode 102, a surface electrode 104 disposed on the surface of the insulating substrate 103, and a pair of side electrodes 105a, 105b The soluble conductor 106 supported by ) is provided. The first external electrode 101 and the second external electrode 102 are supported by the external casing 110 .

The protection element 100 is attached to the current path of the external circuit by connecting the first external electrode 101 and the second external electrode 102 to the external circuit. For this reason, the soluble conductor 106 comprises a part of said electric current path|route. When an overcurrent exceeding the rating flows through the fusible conductor 106, the fusible conductor 106 is melted using self-heating, so that the current path is cut off.

Moreover, in the protection element 100, the heat generating body 107 which heat|fever-generates by electricity supply is formed on the insulating substrate 103. As shown in FIG. The heat generating element 107 contains any one type or two or more types of high melting-point metals, such as W, Mo, and Ru, and is coat|covered with the insulating layer 108, such as glass. The surface electrode 104 is electrically connected to one end of the heat generating body 107 and is disposed and formed on the surface of the insulating layer 108 so as to overlap the heat generating body 107 . In addition, 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. Thereby, electricity supply to the heat generating element 107 is controlled. In the protection element 100, when the overvoltage state of a battery cell is detected other than the case where the soluble conductor 106 is fused in an overcurrent state, since an electric current flows through the heating element 107 formed by the resistor, the heating element 107 The fusible conductor 106 is fused by using the heat of the

In the protection element 100, in order to respond to a large current, the low resistance of the soluble conductor 106 is aimed at by increasing the cross-sectional area of the soluble conductor 106. Here, when the cross-sectional area of the soluble conductor 106 is increased in order to respond to a large current, in order to cut the soluble conductor 106 by fusion using heat generation of the heat generating body 107, time is required, and a soluble conductor at the time of fusing Since the amount of melting of (106) increases, it is necessary to melt-cut the soluble conductor 106 stably. For this reason, in the protection element 100, on the surface of the insulating substrate 103 in both sides of the surface electrode 104, side electrode 105a, 105b is arrange|positioned so that it may mutually be spaced apart. When the soluble conductor 106 is connected to the side electrodes 105a, 105b using solder, when the heat generating body 107 generates heat, the side electrodes 105a and 105b are the heat generated in the heat generating body 107. In order to transmit efficiently to the soluble conductor 106, the soluble conductor 106 is melted while being heated quickly. When the soluble conductor 106 melts, the side electrodes 105a and 105b will use wettability to transfer a part of the melt (melted conductor) of the soluble conductor 106 to the surface electrode 104 and the first external electrode 101 . ) and the second external electrode 102 to keep it spaced apart. Accordingly, in the protection element 100 , the soluble conductor 106 attached to the current path between the first external electrode 101 and the second external electrode 102 is easily cut by melting.

However, in the protection element 100, since the surface electrode 104 and a pair of side electrodes 105a, 105b are arrange|positioned in the limited space on the surface of the insulated substrate 103, the surface electrode 104 and a pair The distance between the side electrodes 105a and 105b of Thereby, after melting of the soluble conductor 106, since a molten conductor becomes easy to connect with the 1st external electrode 101 and the 2nd external electrode 102, there exists a possibility that insulation resistance cannot be ensured.

Moreover, as the insulating substrate 103, while being excellent in thermal shock resistance, the ceramic substrate excellent also in thermal conductivity is used suitably. In this case, since the difference between the coefficient of thermal expansion of the soluble conductor 106 and the coefficient of thermal expansion of the insulating substrate 103 is large, if the protection element 100 is repeatedly placed in a high temperature environment and a low temperature environment, the surface electrode 104 And between a pair of side electrodes 105a, 105b WHEREIN: The distortion resulting from the difference of a thermal expansion coefficient accumulates in the soluble conductor 106. There is also a possibility that it may become difficult to maintain the high rating of the protection element 100 in order to generate|occur|produce dispersion|variation in resistance value by this. Moreover, it originates in said distortion, and there exists a possibility that a crack, peeling, etc. may generate|occur|produce in the soluble conductor 106 and the side electrodes 105a, 105b. In order to improve the rating of the protection element 100, such a tendency becomes remarkable, so that the soluble conductor 106 is enlarged.

Example

Next, an embodiment of the present invention will be described. In this Example, the protective element 1 (Example: see FIG. 1) in which the soluble conductor 6 was supported only by the surface electrode 5 on the insulated substrate 4, and the soluble conductor 106 is insulated After preparing the protection element 100 (comparative example: see FIG. 11) supported by the surface electrode 104 and a pair of side electrodes 105a, 105b on the board|substrate 103, at the time of current interruption Insulation, fusing characteristics using heat generated by the heating elements 11 and 107, and reliability during the temperature cycle test were evaluated.

In the protection element 1 of the Example and the protection element 100 of the comparative example, as the insulating substrates 4 and 103, a ceramic substrate (coefficient of thermal expansion = 7 ppm/° C.) in which the heating elements 11 and 107 were formed on the back surface were used. did Moreover, as the soluble conductors 6 and 106 electrically connected to the 1st external electrodes 2, 101 and the 2nd external electrodes 3, 102, Ag plating process (thickness = 6 micrometers) was given Sn-Ag. -Cu-based metal foil (thickness = 0.35 mm, width = 5.4 mm, coefficient of thermal expansion = 22 ppm/°C) was used. The soluble conductors 6 and 106 and the first external electrodes 2 and 101 and the second external electrodes 3 and 102 were connected via solder. Further, the first external electrodes 2, 101 and the second external electrodes 3, 102 were supported by the PPS external casings 10, 110 (coefficient of thermal expansion = 20 ppm/°C).

With respect to the protection element 1 of an Example and the protection element 100 of a comparative example, the soluble conductors 6 and 106 were melt-cut using self-heating by energizing on the conditions of 190A and 35V. The melting time was about 5 seconds in any of the protection element 1 of an Example and the protection element 100 of a comparative example. After cutting, by measuring the insulation resistance value between the first external electrodes 2 and 101 and the second external electrodes 3 and 102 , it was confirmed whether insulation resistance of 10 ⁶ Ω or more was ensured. Table 1 shows the measurement results.

As shown in Table 1, in the protection element 1 of an Example, in all 16 samples, the insulation resistance of 10 ⁶ ohms or more is ensured. On the other hand, in the protection element 100 of a comparative example, the insulation resistance value became less than 10 ⁶ ohms in three samples among all eight samples. In the protection element 100 of a comparative example, the 1st external electrode 101, the 2nd external electrode 102, the side electrodes 105a, 105b, and the surface electrode 104 are formed by the side electrodes 105a, 105b being formed. ) is close to each other, so it is considered to be the cause that a short circuit occurred easily due to the molten conductor scattered during arc discharge. On the other hand, in the protection element 1 of the Example in which the soluble conductor 6 is supported only by the surface electrode 5 on the insulating substrate 4, since said short circuit does not generate|occur|produce easily, high insulation resistance valid to keep

Moreover, in the protection element 1 of an Example and the protection element 100 of a comparative example, as a result of cutting the soluble conductors 6 and 106 by energizing and heat-generating the heating elements 11 and 107, the protection element 1 of an Example And in any of the protection element 100 of a comparative example, the fusing time was about 10 second under the condition of 30 W of applied power, and the fusing time was about 1.5 second under the condition of 90 W of applied power. That is, the protection element 1 of the embodiment not provided with the side electrodes 105a and 105b is fast in a wide operating power range, similarly to the protection element 100 of the comparative example provided with the side electrodes 105a and 105b. The soluble conductor 6 could be cut by melting.

Next, by performing a temperature cycle test using the protection element 1 of an Example and the protection element 100 of a comparative example, the conduction resistance value of an initial stage and the conduction resistance value after a temperature cycle test were measured. Table 2 shows the measurement results. In the temperature cycle test, the number of cycles was set to 300 while changing the temperature between -40°C (30 min) and 100°C (30 min).

As shown in Table 2, in the protection element 1 of the Example, while the rate of increase of the resistance value after the temperature cycle test was suppressed to 1.4%, in the protection element 100 of the comparative example, after the temperature cycle test The rate of increase of the resistance value increased to 3.9%.

In the protection element 100 of a comparative example, the soluble conductor 106 is being fixed to the insulating board|substrate 103 by the side electrode 105a, 105b and the surface electrode 104 at several points. In this case, when a temperature cycle test is performed, since stress will generate|occur|produce repeatedly due to the difference of the thermal expansion coefficient of the insulated substrate 103, and the thermal expansion coefficient of the soluble conductor 106, the soluble conductor 106 is insulated. Distortion occurs between the side electrodes 105a and 105b fixed to the substrate 103 and the surface electrode 104 . Thereby, since the resistance value fluctuates due to the deformation|transformation of the soluble conductor 106, reliability fell regarding maintenance of a rating, quick-melting-breaking property, etc.

On the other hand, in the protection element 1 of an Example, since the soluble conductor 6 is being fixed to the insulated substrate 4 by the surface electrode 5 at one point, generation|occurrence|production of said distortion is suppressed. Further, since the difference between the coefficient of thermal expansion of the outer casing 10 supporting the first external electrode 2 and the second external electrode 3 and the coefficient of thermal expansion of the soluble conductor 6 is small, the first external electrode 2 ) and little distortion occurs between the second external electrode 3 and the surface electrode 5 . Therefore, even when the protective element 1 is exposed to various temperature environments by employ|adopting the structure in which the soluble conductor 6 was supported only by the surface electrode 5 on the insulated substrate 4, maintenance of a fixed rating and reliability with respect to rapid melting and breaking.

This application claims priority on the basis of Japanese Patent Application No. 2014-112811 for which it applied to Japan Patent Office on May 30, 2014, All content of this application is used for this application by reference. .

Various modifications, combinations, sub-combinations, and changes can be envisaged by those skilled in the art according to design requirements or other factors, but it is understood that they are included within the spirit of the appended claims and their equivalents. .

1: protection element
2: first external electrode
3: second external electrode
4: Insulation substrate
4a: surface
4b: back side
5: surface electrode
6: fusible conductor
7: connection material
10: outer casing
11: heating element
12: protection element
13: insulating layer
15: third external connection electrode
30: battery pack
31 to 34: battery cell
35: battery stack
36: detection circuit
37: current control element
40: charge and discharge control circuit
41, 42: current control element
43: control unit
45: charging device
50: protection element
51: suction hole
52: conductive layer
53: back electrode
55: spare solder

Claims (8)

a first external electrode;
a second external electrode;
an insulating substrate disposed between the first external electrode and the second external electrode;
a surface electrode disposed and formed on the surface of the insulating substrate;
a soluble conductor electrically connected to each of the first external electrode and the second external electrode and supported only by the surface electrode on the surface of the insulating substrate;
and an outer casing supporting each of the first external electrode and the second external electrode. The method of claim 1,
The outer casing is
has a coefficient of thermal expansion equal to that of the fusible conductor,
Or it has a thermal expansion coefficient approximated to the thermal expansion coefficient of the said soluble conductor, The protection element. The method of claim 1,
The said surface electrode is formed in the center part of the surface of the said insulating substrate, The protection element. The method of claim 1,
A protection element provided with a heating element disposed and formed on the insulating substrate or inside the insulating substrate. The method of claim 1,
The insulating substrate has one or more suction holes in the thickness direction,
The said 1 or more suction hole attract|sucks the molten conductor which is a melt|molten material of the said soluble conductor, The protection element. The method of claim 1,
The protection element, 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. one or more battery cells;
a protection element connected to the one or more battery cells so as to be able to block the current flowing in the one or more battery cells;
a current control element for controlling a current for heating the protection element while detecting a voltage value of each of the one or more battery cells;
The protection element is
a first external electrode;
a second external electrode;
an insulating substrate disposed between the first external electrode and the second external electrode;
a surface electrode disposed and formed on the surface of the insulating substrate;
a soluble conductor electrically connected to each of the first external electrode and the second external electrode and supported only by the surface electrode on the surface of the insulating substrate;
and an outer casing supporting each of the first external electrode and the second external electrode. delete

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