WO2018110154A1 - Protective element - Google Patents

Abstract

Provided is a protective element with which the improvement of the current rating and the execution of a quick current interruption during an anomaly are both achieved, thereby increasing insulation reliability after the current interruption. The protective element comprises: an insulation base board 10; first and second electrodes 11, 12 disposed on the insulation base board 10; a heating element 14 formed on the insulation base board 10; a heating element extraction electrode 16 electrically connected to the heating element 14; fusible conductors 31, 32 establishing via the heating element extraction electrode 16 a connection between the first and second electrodes 11, 12; and a retention member 24 provided above the heating element extraction electrode 16, which retains wetting and spreading melts from the fusible conductors 31, 32 that have fused.

Description

Protective element

This technology relates to a protective element that cuts off the power line and signal line. This application claims priority on the basis of Japanese Patent Application No. 2016-240735 filed on December 12, 2016 in Japan. This application is incorporated herein by reference. Incorporated.

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

This type of protection element performs overcharge protection or overdischarge protection operation of the battery pack by turning on / off the output using a FET (Field Effect Transistor) switch built in the battery pack. . However, when the FET switch is short-circuited for some reason, a lightning surge or the like is applied and an instantaneous large current flows, or the output voltage drops abnormally due to the life of the battery cell, or excessively abnormal Even when voltage is output, battery packs and electronic devices must be protected from accidents such as ignition. Therefore, in any abnormal state that can be assumed, a protection element having a function of cutting off a current path with a signal from the outside is used in order to safely cut off the output of the battery cell.

As a blocking element of a protection circuit for a lithium ion secondary battery or the like, as shown in FIGS. 24A and 24B, a first electrode 91, a heating element extraction electrode 95, and a second electrode 92 on a current path are used. The fusible conductor 93 is connected to form part of the current path, and the fusible conductor 93 on the current path is melted by self-heating due to overcurrent or by a heating element 94 provided inside the protective element. There is a thing (refer patent document 1). In such a protective element 90, the molten liquid soluble conductor 93 is collected on the heating element extraction electrode 95 connected to the heating element 94 and the first and second electrodes 91, 92, thereby collecting the first and second electrodes. The electrodes 91 and 92 are separated from each other to interrupt the current path.

The protective element is an exterior component so that the fusible conductor 93 is melted by the heat generated by the heating element 94, and the fusible conductor 93 is melted by self-heating due to overcurrent. The cover member 97 is sealed. In addition, the protective element 90 is provided with an internal space for melting and flowing the soluble conductor 93 by the cover member 97 in order to stably realize the fusing action of the soluble conductor 93 by the heating element 94.

The protective element 90 is coated with a flux 98 that prevents oxidation of the surface of the soluble conductor 93 and removes an oxide film on the surface of the soluble conductor 93 in order to maintain fast fusing properties.

Japanese Patent No. 4110967 Japanese Patent Laying-Open No. 2015-97183

Such a surface-mount type protection element is required to have an improved current rating in accordance with an increase in capacity and rating of electronic devices and battery packs to be mounted.

In order to increase the current rating, a fusible conductor with a larger volume will be used to reduce the resistance value. There is a problem that it takes time and current cannot be interrupted instantaneously when an abnormality occurs in an electric circuit or the like.

Therefore, by providing a groove extending in the current direction in the fusible conductor and increasing the fusing start point in the low melting point metal body, the operation time is shortened and the operation time is stabilized while increasing the volume and increasing the current capacity. Has been proposed (see Patent Document 1).

Here, as shown in FIGS. 24, 25 (A) and 25 (B), the surface mount type protection element 90 with the heating element has first and second electrodes 91 whose both ends are connected to the energization path of the device. , 92 and a heating conductor lead electrode 95 for energizing the heating element 94 in the middle thereof, the soluble conductor 93 is disposed on the three electrodes. When the fusible conductor 93 is melted by the heat generated by the heating element 94, it rises and aggregates on the three electrodes 91, 92, 95, so that the heating element extraction electrode 95 and the first and second electrodes 91, 92 are located. Are separated and the current is cut off. However, when the volume of the fusible conductor 93 increases, the molten conductor does not fit on the heating element extraction electrode 95 as shown in FIGS. 25 (C) and 25 (D), and the first and second electrodes 91 and 92 There is a risk that the insulation reliability after interruption will be impaired.

Moreover, since the soluble conductor 93 is mounted over the first and second electrodes 91 and 92 and the heating element extraction electrode 95, it takes a heating time until the entire soluble conductor 93 is melted, and the volume is increased. In proportion to this, the fusing time is extended, and it is difficult to quickly cut off the power supply when there is an abnormality.

Therefore, an object of the present technology is to provide a protection element that improves current rating and improves insulation reliability after current interruption.

In order to solve the above-described problems, a protection element according to the present technology includes an insulating substrate, first and second electrodes provided on the insulating substrate, a heating element formed on the insulating substrate, and the heat generation. A heating element extraction electrode electrically connected to the body, a soluble conductor connecting the first and second electrodes via the heating element extraction electrode, and the heating element extraction electrode. And a holding member that holds and spreads the melt in which the soluble conductor is melted.

According to the present technology, by providing the holding member on the heating element extraction electrode, it is possible to increase the amount of the molten material held on the heating element extraction electrode, and the soluble conductor increases in size as the rating is improved. Also in this case, it is possible to prevent the melt from protruding from the heating element extraction electrode and short-circuiting between the first and second electrodes.

FIG. 1A is an external perspective view showing a protective element having a prismatic holding member with a case omitted, and FIG. 1B is a cross-sectional view showing a circuit module to which the present technology is applied. FIG. 2A is a plan view showing a state before the fusible conductor of the protection element provided with the prismatic holding member is blown, and FIG. 2B is a front view showing the state before the fusible conductor is blown. FIG. 2C is a plan view showing a state where the soluble conductor is melted, and FIG. 2D is a side view showing the state where the soluble conductor is melted. FIG. 3 is an external perspective view showing a protection element to which the present technology is applied. FIG. 4 is an external perspective view showing a protective element using a laminated soluble conductor having a low melting point metal layer constituting an inner layer and a high melting point metal layer constituting an outer layer, with the case omitted. FIG. 5 (A) is a plan view showing the state before the fusible conductor of the protection element provided with the cylindrical holding member is blown, and FIG. 5 (B) is a front view showing the state before the fusible conductor is blown. FIG. 5C is a plan view showing a state where the fusible conductor is blown, and FIG. 5D is a side view showing a state where the fusible conductor is blown. FIG. 6A is a plan view showing a state before the fusible conductor of the protection element provided with the cylindrical holding member is blown, and FIG. 6B is a front view showing the state before the fusible conductor is blown. FIG. 6C is a plan view showing a state in which the soluble conductor is blown out, and FIG. 6D is a side view showing a state in which the soluble conductor is blown out. FIG. 7A is a plan view showing a state before the fusible conductor of the protective element having the semi-cylindrical holding member is blown, and FIG. 7B is a front view showing the state before the fusible conductor is blown. FIG. 7C is a plan view showing a state where the soluble conductor is blown out, and FIG. 7D is a side view showing a state where the soluble conductor is blown out. FIG. 8A is a plan view showing a state before the fusible conductor of the protective element provided with the helical holding member, and FIG. 8B is a front view showing the state before the fusible conductor is blown. FIG. 8 (C) is a plan view showing a state where the soluble conductor is blown out, and FIG. 8 (D) is a side view showing a state where the soluble conductor is blown out. FIG. 9 (A) is a plan view showing a state before the fusible conductor of the protective element having a bar-shaped holding member having a T-shaped cross section is blown, and FIG. 9 (B) is before the fusible conductor is blown. It is a front view which shows a state, FIG.9 (C) is a top view which shows the state by which the soluble conductor was blown out, FIG.9 (D) is a side view which shows the state by which the soluble conductor was blown out. FIG. 10 is an external perspective view showing a protective element provided with a rod-shaped holding member having a T-shaped cross section, omitting the case. FIG. 11 (A) is a plan view showing a state before the fusible conductor of the protective element provided with the cylindrical holding member in which the slit is formed, and FIG. 11 (B) is a state before the fusible conductor is blown. FIG. 11C is a plan view showing a state in which a soluble conductor is blown out, and FIG. 11D is a side view showing a state in which the soluble conductor is blown out. FIG. 12A is a plan view showing a state before the fusible conductor of the protective element provided with the semi-cylindrical holding member in which the opening is formed, and FIG. 12 (C) is a plan view showing a state in which a soluble conductor is blown out, and FIG. 12 (D) is a side view showing a state in which the soluble conductor is blown out. . FIG. 13A is a plan view showing the state before the fusible conductor piece of the protective element having the fusible conductor piece and the prismatic holding member is blown, and FIG. 13B is the fusing of the fusible conductor piece. It is a front view which shows the previous state, FIG.13 (C) is a top view which shows the state by which the soluble conductor piece was blown out, FIG.13 (D) is the side surface which shows the state by which the soluble conductor piece was blown out FIG. FIG. 14A is a plan view showing a state before the fusible conductor piece of the protective element having the fusible conductor piece and the cylindrical holding member is blown, and FIG. 14B is the fusing of the fusible conductor piece. It is a front view which shows the previous state, FIG.14 (C) is a top view which shows the state by which the soluble conductor piece was blown out, FIG.14 (D) is the side surface which shows the state by which the soluble conductor piece was blown out FIG. FIG. 15A is a plan view showing a state before the fusible conductor piece of the protective element provided with the fusible conductor piece and the cylindrical holding member, and FIG. 15B is a fusing state of the fusible conductor piece. FIG. 15C is a front view showing a previous state, FIG. 15C is a plan view showing a state where a soluble conductor piece is blown, and FIG. 15D is a side view showing a state where the soluble conductor piece is blown. FIG. FIG. 16A is a plan view showing the state before the fusible conductor piece of the protective element having the fusible conductor piece and the semicylindrical holding member is blown, and FIG. It is a front view which shows the state before fusing, FIG.16 (C) is a top view which shows the state by which the soluble conductor piece was blown, and FIG.16 (D) shows the state by which the soluble conductor piece was blown out. It is a side view. FIG. 17A is a plan view showing a state before fusing of a fusible conductor piece of a protective element having a fusible conductor piece and a cylindrical holding member in which a slit is formed, and FIG. FIG. 17C is a front view showing a state before the conductor piece is blown, FIG. 17C is a plan view showing a state where the soluble conductor piece is blown, and FIG. 17D is a view showing the case where the soluble conductor piece is blown. It is a side view which shows a state. FIG. 18 (A) is a plan view showing a state before the fusible conductor piece of the protective element including the fusible conductor piece and the semi-cylindrical holding member in which the opening is formed, and FIG. It is a front view which shows the state before melt | disconnection of a soluble conductor piece, FIG.18 (C) is a top view which shows the state by which the soluble conductor piece was blown, and FIG.18 (D) is a meltable conductor piece blown out. It is a side view which shows the state made. FIG. 19A is a plan view showing a state before the fusible conductor piece of the protection element having the fusible conductor piece and the rod-shaped holding member having a T-shaped cross section, and FIG. FIG. 19 (C) is a plan view showing a state where a soluble conductor piece is blown, and FIG. 19 (D) is a view showing a state where the soluble conductor piece is blown. It is a side view which shows the state. FIG. 20A is a plan view showing a state before the fusible conductor piece of the protective element having the fusible conductor piece and the helical member holding member, and FIG. 20B shows the state of the fusible conductor piece. It is a front view which shows the state before fusing, FIG.20 (C) is a top view which shows the state by which the soluble conductor piece was blown, and FIG.20 (D) shows the state by which the soluble conductor piece was blown out. It is a side view. FIG. 21 is an external perspective view showing a protective element using a laminated soluble conductor piece including a low melting point metal layer constituting an inner layer and a high melting point metal layer constituting an outer layer, with the case omitted. FIG. 22 is a circuit diagram showing a configuration example of a battery circuit using a protection element to which the present invention is applied. FIG. 23 is a circuit diagram of a protection element to which the present invention is applied. FIG. 24 is a diagram showing a conventional protection element in which one soluble conductor is mounted across the heating element extraction electrode between the first and second electrodes, with the case omitted, and FIG. FIG. 24B is an external perspective view, and FIG. 24B is a cross-sectional view. FIG. 25A is a plan view showing a state before the fusible conductor of the conventional protective element is blown, and FIG. 25B is a front view showing the state before the fusible conductor is blown. FIG. 25C is a plan view showing a state where the soluble conductor is blown, and FIG. 25D is a side view showing a state where the soluble conductor is blown.

Hereinafter, a protection element to which the present technology is applied will be described in detail with reference to the drawings. In addition, this technique is not limited only to the following embodiment, Of course, a various change is possible in the range which does not deviate from the summary of this technique. Further, the drawings are schematic, and the ratio of each dimension may be different from the actual one. Specific dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

As shown in FIG. 1, a protective element 1 to which the present invention is applied constitutes a circuit module 3 by being surface-mounted on a circuit board 2. The circuit board 2 is formed with, for example, a protection circuit for a lithium ion secondary battery, and the protective element 1 is surface-mounted, whereby the first and second soluble conductors are formed on the charge / discharge path of the lithium ion secondary battery. 31, 32 are incorporated. When a large current exceeding the rating of the protection element 1 flows, the circuit module 3 blocks the current path by fusing the first and second fusible conductors 31 and 32 by self-heating (Joule heat). Further, the circuit module 3 energizes the heating element 14 at a predetermined timing by a current control element provided on the circuit board 2 or the like, and the first and second soluble conductors 31 and 32 are blown by the heat generation of the heating element 14. By doing so, the current path can be cut off. 1A is a plan view showing the protective element 1 to which the present invention is applied with the case omitted, and FIG. 1B is a cross-sectional view of the circuit module 3 to which the present invention is applied. It is.

[Protective element]
As shown in FIG. 1A, the protection element 1 includes an insulating substrate 10, a heating element 14 laminated on the insulating substrate 10 and covered with an insulating member 15, and a first formed on both ends of the insulating substrate 10. The electrode 11 and the second electrode 12, the heating element extraction electrode 16 laminated on the insulating member 15 so as to overlap the heating element 14, and the first electrode 11 mounted from the first electrode 11 to the heating element extraction electrode 16. One soluble conductor 31, a second soluble conductor 32 mounted from the second electrode 12 to the heating element extraction electrode 16, and the first and second soluble conductors provided on the heating element extraction electrode 16. A holding member 24 that holds the molten body 31 and 32 on the heating element extraction electrode 16 is provided.

The insulating substrate 10 is formed in a substantially square shape by an insulating member such as alumina, glass ceramics, mullite, zirconia. In addition, the insulating substrate 10 may be made of a material used for a printed wiring board such as a glass epoxy board or a phenol board, but attention should be paid to the temperature at which the first and second fusible conductors 31 and 32 are melted. There is a need to.

[First and second electrodes]
As shown in FIGS. 2A and 2B, the first and second electrodes 11 and 12 are arranged on the surface 10a of the insulating substrate 10 so as to be spaced apart from each other in the vicinity of opposite side edges. The first and second soluble conductors 31 and 32 and the heating element extraction are opened by mounting the first and second soluble conductors 31 and 32 between the heating element extraction electrodes 16 described later. It is electrically connected through the electrode 16. Further, as shown in FIGS. 2C and 2D, the first and second electrodes 11 and 12 pass a large current exceeding the rating through the protective element 1 and the first and second soluble conductors 31 and 32. Is cut off due to self-heating (Joule heat), or the heating element 14 generates heat when energized, and the first and second soluble conductors 31 and 32 are fused between the heating element lead electrode 16 and cut off. Is done.

As shown in FIG. 3, the first and second electrodes 11 and 12 are provided on the back surface 10 f via castellations provided on the first and second side surfaces 10 b and 10 c of the insulating substrate 10, respectively. The external connection electrodes 11a and 12a are connected. The protection element 1 is connected to the circuit board 2 on which an external circuit is formed via the external connection electrodes 11a and 12a, and constitutes a part of the energization path of the external circuit.

The first and second electrodes 11 and 12 can be formed using a general electrode material such as Cu or Ag. In addition, a coating such as Ni / Au plating, Ni / Pd plating, or Ni / Pd / Au plating is coated on the surfaces of the first and second electrodes 11 and 12 by a known method such as plating. Preferably it is. Thereby, the protection element 1 can prevent the oxidation of the first and second electrodes 11 and 12, and can prevent the fluctuation of the rating due to the increase of the conduction resistance. Further, when the protective element 1 is mounted by reflow soldering, a low melting point that forms connection solder for connecting the first and second soluble conductors 31 and 32 or an outer layer of the first and second soluble conductors 31 and 32. It is possible to prevent the first and second electrodes 11 and 12 from being eroded (soldered) by melting the metal.

[Heating element]
The heating element 14 is a conductive member that generates heat when energized, and is made of, for example, W, Mo, Ru, Cu, Ag, or an alloy containing these as main components. The heating element 14 is obtained by mixing a powdered material of these alloys, compositions, or compounds with a resin binder or the like, forming a paste on the insulating substrate 10 using a screen printing technique, and firing it. Etc. can be formed. The heating element 14 has one end connected to the first heating element electrode 18 and the other end connected to the second heating element electrode 19.

In the protection element 1, an insulating member 15 is disposed so as to cover the heating element 14, and a heating element extraction electrode 16 is formed so as to overlap the heating element 14 via the insulating member 15. Thereby, the protection element 1 can efficiently transmit the heat of the heating element 14 to the heating element extraction electrode 16. In order to efficiently transmit the heat of the heating element 14 to the first and second soluble conductors 31 and 32, the insulating member 15 may be laminated between the heating element 14 and the insulating substrate 10. As the insulating member 15, for example, glass can be used.

One end of the heating element extraction electrode 16 is connected to the first heating element electrode 18 and is connected to one end of the heating element 14 via the first heating element electrode 18. The first heating element electrode 18 is formed on the third side surface 10 d side of the insulating substrate 10, and the second heating element electrode 19 is formed on the fourth side surface 10 e side of the insulating substrate 10. The second heating element electrode 19 is connected to an external connection electrode 19a formed on the back surface 10f of the insulating substrate 10 through a castellation formed on the fourth side surface 10e.

The heating element 14 is connected to an external circuit formed on the circuit board 2 via the external connection electrode 19a by mounting the protection element 1 on the circuit board 2. The heating element 14 is energized through the external connection electrode 19a at a predetermined timing to cut off the energization path of the external circuit, and generates heat to connect the first and second electrodes 11 and 12. 1 and the 2nd soluble conductor 31 and 32 can be blown out. Further, the heating element 14 stops its heat generation because the first and second fusible conductors 31 and 32 are melted to shut off the current-carrying path.

[First and second soluble conductors]
The first soluble conductor 31 is mounted from the first electrode 11 to the heating element extraction electrode 16, and the second soluble conductor 32 is mounted from the second electrode 12 to the heating element extraction electrode 16. The first and second fusible conductors 31 and 32 are separated from each other on the heating element extraction electrode 16.

The first soluble conductor 31 has, for example, a rectangular plate shape, and is connected to the first electrode 11 side edge portion of the heating element extraction electrode 16 and the first electrode 11. Similarly, the second fusible conductor 32 has, for example, a rectangular plate shape, and is connected to the side edge of the heating element extraction electrode 16 on the second electrode 12 side and the second electrode 12. As a result, the protective element 1 is configured with an energization path that spans the first electrode 11, the first soluble conductor 31, the heating element extraction electrode 16, the second soluble conductor 32, and the second electrode 12.

Such a protection element 1 divides the fusible conductor constituting the energization path between the first and second electrodes 11 and 12 into the first and second fusible conductors 31 and 32 to generate a heating element extraction electrode. 16 and the heating element extraction electrode 16 is used as an energization path between the first and second electrodes 11 and 12. Thereby, the protection element 1 is on the heating element extraction electrode 16 as compared with the conventional protection element in which one soluble conductor is mounted across the heating element extraction electrode between the first and second electrodes. The volume of the soluble conductor between the first and second soluble conductors 31 and 32 is reduced.

That is, in the conventional protection element, the soluble conductor at the center of the heating element extraction electrode 16 that does not directly contribute to the interruption of the conduction path between the first and second electrodes 11 and 12 is melted. Since the fusible conductor is located immediately above the heating element 14, the fusible conductor has been melted before the first and second electrodes 11 and 12.

On the other hand, the protection element 1 has the first and second fusible conductors 31 and 32 connected to each other on the heating element extraction electrode 16 so as to be melted by the heat generated by the heating element 14 when the current is interrupted. The volume of the conductor can be reduced, and the heat of the heating element can be reduced between the first electrode 11 and the heating element extraction electrode 16 to be fused and between the second electrode 12 and the heating element extraction electrode 16. The first and second fusible conductors 31 and 32 can be efficiently transmitted, and the energization path between the first and second electrodes 11 and 12 can be quickly cut off.

Further, the protection element 1 using the heating element extraction electrode 16 as a current-carrying path between the first and second electrodes 11 and 12 has a single soluble conductor extending between the first and second electrodes. The current rating is maintained even when compared with the conventional protection elements that are installed across the board. Accordingly, the current path between the first and second electrodes 11 and 12 can be quickly cut off as much as the volume of the fusible conductor to be blown is reduced compared to the conventional protection element having the same current rating. it can.

Further, since the volume of the soluble conductor to be melted is reduced, the protective element 1 does not overflow the molten conductor from the heating element extraction electrode 16, and reliably between the first and second electrodes 11, 12. Can be cut off, and the insulation reliability after the turning off of the current can be improved (see FIGS. 2C and 2D).

The first and second fusible conductors 31 and 32 are made of a material that is quickly melted by the heat generated by the heating element 14, and are preferably made of a low melting point metal such as solder or Pb-free solder mainly composed of Sn. Can be used.

The first and second soluble conductors 31 and 32 can be formed using metal such as In, Sn, Pb, Ag, Cu, or an alloy mainly containing any of these. Further, as shown in FIG. 4, the first and second soluble conductors 31 and 32 may be laminated bodies in which the inner layer is a low melting point metal and the outer layer is a high melting point metal. In the first and second soluble conductors 31 and 32, for example, the inner low-melting-point metal layer 33 can be composed of a solder foil or the like, and the outer high-melting-point metal layer 34 can be composed of an Ag plating layer or the like. The first and second fusible conductors 31 and 32 have a laminated structure in which the inner layer is a low melting point metal layer 33 and the outer layer is a high melting point metal layer 34, so that when the protective element 1 is reflow mounted, Even when the temperature exceeds the melting temperature of the low melting point metal and the low melting point metal is melted, the outflow of the low melting point metal to the outside is suppressed and the shapes of the first and second soluble conductors 31 and 32 are maintained. be able to. Therefore, the first and second fusible conductors 31 and 32 are not melted at a predetermined temperature due to local increase or decrease in resistance value due to deformation, or melted at a temperature lower than the predetermined temperature. Variations in characteristics can be prevented. In addition, the first and second soluble conductors 31 and 32 are melted (soldered) by melting the low melting point metal even when fusing, so that the melting point of the high melting point metal is below the melting point of the high melting point metal. Can be quickly melted at a temperature of

The first and second soluble conductors 31 and 32 are connected to the heating element extraction electrode 16 and the first and second electrodes 11 and 12 by solder or the like. The first and second fusible conductors 31 and 32 can be easily connected by reflow soldering.

The first and second soluble conductors 31 and 32 are preferably coated with a flux 23 to prevent oxidation, improve wettability, and the like.

[Holding member]
A holding member 24 is provided on the heating element extraction electrode 16. The holding member 24 increases the holding amount for holding the melt of the heating element extraction electrode 16 when the melt of the melted first and second soluble conductors 31 and 32 is wetted and spread. By providing the holding member 24 on the heating element extraction electrode 16, it is possible to increase the amount of the melt held on the heating element extraction electrode 16, and when the soluble conductor increases in size as the rating is improved. In addition, it is possible to prevent the melt from protruding from the heating element extraction electrode 16 and short-circuiting between the first and second electrodes 11 and 12.

The holding member 24 is mounted on the heating element extraction electrode 16 with a connection material 25 such as a thermosetting adhesive, solder or other low melting point metal paste. By using a conductive material such as solder as the connection material 25, it can also be used as a connection material for connecting the first and second soluble conductors 31 and 32 to the heating element extraction electrode 16.

As shown in FIG. 2, the holding member 24 is preferably provided in the center of the heating element extraction electrode 16 in order to hold more melt. The holding member 24 is preferably provided between the first soluble conductor and the second soluble conductor. When the fusible conductor is divided and disposed between the first and second electrodes 11 and 12 and the heating element extraction electrode 16 like the first and second fusible conductors 31 and 32, the holding member 24. Is provided between the first soluble conductor and the second soluble conductor, so that the melt of both the soluble conductors 31 and 32 can be efficiently held, and the current path on the first electrode 11 side. Both of the current paths on the second electrode 12 side can be reliably cut off.

The holding member 24 has a length equal to or greater than the width of the first and second fusible conductors 31 and 32 and faces at least both ends in the width direction of the first and second fusible conductors 31 and 32. It is preferable to be provided at the position. As a result, the holding member 24 wets and spreads the melt over the entire width of the first and second fusible conductors 31 and 32, so that the first and second electrodes 11 and 12 and the heating element extraction electrode 16 A short circuit can be prevented.

Further, the holding member 24 has a length equal to or greater than the width of the first and second electrodes 11 and 12 and is provided at a position facing at least both ends in the width direction of the first and second electrodes 11 and 12. It is preferable. As a result, the holding member 24 increases the holding amount of the melt of the heating element extraction electrode 16, and the melting body and the heating element extraction electrode 16 at both longitudinal ends of the first and second electrodes 11 and 12. A short circuit can be prevented.

The holding member 24 is preferably provided over substantially the entire length of the heating element extraction electrode 16 in the longitudinal direction. As a result, the holding member 24 increases the holding amount of the melt of the heating element extraction electrode 16, and the melt is formed between the first and second electrodes 11, 12 at both ends in the longitudinal direction of the heating element extraction electrode 16. A short circuit can be prevented.

It is preferable that the holding member 24 is made of a material in which the melt of the first and second soluble conductors 31 and 32 such as a metal easily spreads. Alternatively, the holding member 24 is preferably subjected to a surface treatment such as a plating treatment that improves the wetness of the melt of the first and second soluble conductors 31 and 32. For example, the holding member 24 is surface-treated by tin plating, nickel plating, or the like, thereby improving the wettability of the melt and preventing oxidation.

The holding member 24 can be formed as a prismatic body extending over the longitudinal direction of the heating element extraction electrode, for example, as shown in FIGS. 2 (A) to (D) and FIG. The prismatic holding member 24A can increase the surface area where the melt of the first and second fusible conductors 31 and 32 spreads by increasing the height and width, and the melt on the heating element extraction electrode 16 can be increased. The holding amount of can be increased.

Further, as shown in FIGS. 5A to 5D, the holding member 24 can be formed as a columnar body extending along the longitudinal direction of the heating element extraction electrode. In the cylindrical holding member 24B, the melt of the first and second soluble conductors easily spreads around the periphery, and the retainability of the melt on the heating element extraction electrode 16 is improved.

Further, as shown in FIGS. 6A to 6D, the holding member 24 can be formed as a cylindrical body extending along the longitudinal direction of the heating element extraction electrode. In addition to the characteristics of the columnar holding member 24, the cylindrical holding member 24 </ b> C can be expected to flow the melt into the cylinder, and can hold more melt.

Further, as shown in FIGS. 7A to 7D, the holding member 24 can be formed as a semi-cylindrical body extending over the longitudinal direction of the heating element extraction electrode. In addition to the characteristics of the columnar holding member 24, the semi-cylindrical holding member 24D can flow more melt into the cylinder, and can hold more melt.

Further, as shown in FIGS. 8A to 8D, the holding member 24 can be formed as a spiral body extending along the longitudinal direction of the heating element extraction electrode. The spiral holding member 24E is formed by spirally winding a metal with good wettability of the melt or a plated wire, and uses a capillary phenomenon to make the first and second pitches between the narrow pitches of the wire. The melt of the two soluble conductors 31 and 32 can be introduced and held.

Further, as shown in FIGS. 9A to 9D and FIG. 10, the holding member 24 extends in the longitudinal direction of the heating element extraction electrode and is connected to the heating element extraction electrode 16. And a protrusion 29 protruding from the base portion 28 onto the heating element extraction electrode 16 can be formed as a rod-shaped body having a T-shaped cross section. The holding member 24F having a T-shaped cross section can be stably mounted on the heating element extraction electrode 16 by being provided with the base portion 28, and the first and second possible portions can be increased by increasing the height and width of the protruding portion 29. The surface area over which the melt of the molten conductors 31 and 32 spreads out can be increased, and the amount of the melt retained on the heating element extraction electrode 16 can be increased.

[Through or non-penetrating slit / opening]
The holding member 24 may form one or a plurality of penetrating or non-penetrating slits or one or a plurality of penetrating or non-penetrating openings extending in a direction substantially orthogonal to the longitudinal direction. As a result, the holding member 24 increases the surface area where the melt is wet and spreads, and can flow in and hold a larger amount of the melt using a capillary phenomenon to a narrow slit or opening.

For example, as shown in FIG. 11, the cylindrical holding member 24C may form a plurality of slits 26 extending in the circumferential direction substantially orthogonal to the longitudinal direction. The slit 26 penetrates the inside of the cylinder and is formed over the half circumference of the cylinder. The cylindrical holding member 24C is installed with the slit 26 facing the heating element extraction electrode 16 side. Thereby, the cylindrical holding member 24C causes capillary action between the heating element extraction electrode 16 and the slit 26, and draws the melt of the first and second soluble conductors 31 and 32 into the cylinder. Can be held.

For example, as shown in FIG. 12, the semi-cylindrical holding member 24D may form a plurality of openings 27. The opening 27 is formed through the cylinder. The semi-cylindrical holding member 24D is installed with the opening 27 facing the heating element extraction electrode 16 side. Thereby, the semi-cylindrical holding member 24D causes a capillary phenomenon to act between the heating element extraction electrode 16 and the opening 27, and melts the first and second soluble conductors 31 and 32 into the cylinder. Can be retracted and held.

In addition, the holding member 24 has one or a plurality of non-penetrating slits 26 and openings 27 on the base 28 of the prismatic holding member 24A, the columnar holding member 24B, and the T-shaped holding member 24F. May be formed. Also in this case, by installing the slit 26 and the opening 27 toward the heating element extraction electrode 16 side, a capillary phenomenon acts between the heating element extraction electrode 16 and the slit 26 and the opening 27, and the first, The melt of the second soluble conductors 31 and 32 can be drawn into the slit 26 and the opening 27 and held. In addition, the holding member 24 may form one or a plurality of penetrating or non-penetrating slits 26 and openings 27 in the protrusions 29 of the holding member 24F having a T-shaped cross section.

The shape of the holding member 24 may be, for example, a shape meandering along the longitudinal direction of the heating element extraction electrode 16 in addition to the above-described one. The holding member 24 may have a plurality of small holding members arranged along the longitudinal direction or the width direction of the heating element extraction electrode 16. The shape and arrangement of the holding member 24 that holds the melt of the soluble conductor can be appropriately set according to the layout of the protective element such as the amount of the melt held and the shape and arrangement of the soluble conductor.

[Case]
In addition, the protective element 1 is provided with a case 20 on the surface 10a of the insulating substrate 10 in order to protect the inside. The case 20 is formed in a substantially rectangular shape according to the shape of the insulating substrate 10. As shown in FIG. 1B, the case 20 includes a side surface 21 connected to the surface 10a of the insulating substrate 10 provided with the soluble conductor 13, and a top surface that covers the surface 10a of the insulating substrate 10. 22, the fusible conductor 13 expands spherically on the surface 10 a of the insulating substrate 10 when melted, and the molten conductor aggregates on the heating element extraction electrode 16 and the first and second electrodes 11, 12. Enough internal space.

In the protection element 1, the holding member 24 may be provided on the top surface 22 of the case 20 on the heating element extraction electrode 16. That is, the holding member 24 may protrude from the top surface 22 of the case 20 into the protective element 1 and face the heating element extraction electrode 16. At this time, the holding member 24 may be in contact with the surface of the heating element extraction electrode 16 and may be in close proximity but may not be in contact. The holding member 24 may be connected to the heating element extraction electrode 16 via the connection material 25 described above provided on the surface of the heating element extraction electrode 16.

Since the protective element 1 is provided with the holding member 24 on the top surface 22 of the case 20, the holding member 24 is provided on the heating element extraction electrode 16 in a state of being separated from the heating element extraction electrode 16. In addition to the configuration in which the first and second fusible conductors 31 and 32 are divided and connected to the heating element extraction electrode 16, one fusible conductor generates heat between the first and second electrodes 11 and 12. You may make it mount so that the body extraction electrode 16 may be straddled.

[Soluble conductor piece]
Further, as shown in FIGS. 13 (A) to (D) to FIGS. 20 (A) to (D), the protection element 1 includes a plurality of first and second fusible conductors 31 and 32, instead of a plurality of soluble conductors 31 and 32. The small first and second soluble conductor pieces 31A and 32A may be connected independently in parallel across the first and second electrodes 11 and 12 and the heating element extraction electrode 16. The fusible conductor pieces 31A and 32A are made of the same material as the first and second fusible conductors 31 and 32 and are smaller than the first and second fusible conductors 31 and 32. It is. The protective element 1 shown in FIGS. 13 (A) to (D) to FIGS. 20 (A) to (D) replaces the first and second soluble conductors 31 and 32 with a plurality of first possible elements. 2 (A) to (A) described above except that the molten conductor pieces 31A-1, 31A-2, 31A-3 and the second soluble conductor pieces 32A-1, 32A-2, 32A-3 are mounted. D) to the configurations shown in FIGS. 8A to 8D.

The protective element 1 includes, for example, three soluble conductor pieces 31A-1, 31A-2, and 31A-3 that are independently arranged in parallel at predetermined intervals, and three soluble conductor pieces 32A-1, 32A-2 and 32A-3 may be arranged in parallel.

The protective element 1 can easily adjust the current capacity by adjusting the number of the soluble conductor pieces 31A and 32A by arranging the plurality of soluble conductor pieces 31A and 32A in parallel.

Further, the protective element 1 prevents the deformation of each of the soluble conductor pieces 31A and 32A by arranging a plurality of the soluble conductor pieces 31A and 32A in parallel while having the same current capacity as that of one soluble conductor. Thus, fluctuations in the fusing characteristics can be prevented. For example, a laminated soluble conductor in which the inner low melting point metal layer described above is coated with an outer high melting point metal layer, when the planar dimension increases, the inner low melting point metal layer melts and flows during reflow heating. By doing so, deformation is likely to occur. As a result, the fusible conductor has a locally thickened portion and a thinned portion, resulting in variations in resistance values, and the fusing characteristics may not be maintained.

Therefore, the protective element 1 has a plurality of fusible conductor pieces 31A and 32A arranged in parallel, thereby reducing the planar dimensions of the fusible conductor pieces 31A and 32A, and preventing deformation due to heat even during reflow heating, Fusing characteristics can be maintained.

Further, in the protective element in which one soluble conductor is mounted across the heating element extraction electrode between the first and second electrodes, if the planar dimension of the soluble conductor is increased to increase the current capacity, the heating element Since the contact area with the extraction electrode becomes wide, if the high melting point metal layer is deformed by heating and flowing of the low melting point metal layer, the straddled heating element extraction electrode may be destroyed (stripped). was there. However, the protection element 1 can be prevented from being deformed by being divided and connected to the plurality of soluble conductor pieces 31A and 32A, and there is no risk of destroying the heating element extraction electrode 16, and the resistance to thermal shock can be improved. it can.

As shown in FIGS. 13 (A) to (D) to FIGS. 20 (A) to (D), the protective element 1 has the fusible conductor pieces 31A and 32A formed in a substantially rectangular shape in plan view, Although the connection is made so that the longitudinal direction is directed along the energization direction, the connection may be made so that the longitudinal direction forms an arbitrary angle with respect to the energization direction. By connecting the fusible conductor pieces 31A and 32A at an angle with respect to the energizing direction, the protective element 1 changes the installation area on the first and second electrodes 11 and 12 and the heating element lead electrode 16, and the entire element Current capacity can be adjusted.

Further, as shown in FIG. 21, the protective element 1 may be formed by forming the soluble conductor pieces 31A and 32A as a laminate composed of an inner layer of a low melting point metal and an outer layer of a high melting point metal. The fusible conductor pieces 31A and 32A are configured by, for example, forming the inner low-melting-point metal layer 33 with a solder foil or the like in the same manner as the first and second fusible conductors 31 and 32 of the laminated type described above. The melting point metal layer 34 can be composed of an Ag plating layer or the like. The fusible conductor pieces 31A and 32A have a laminated structure in which the inner layer is the low-melting-point metal layer 33 and the outer layer is the high-melting-point metal layer 34, so that miniaturization and higher rating can be realized, and the protective element 1 is In the case of reflow mounting, the shape can be maintained even when the reflow temperature exceeds the melting temperature of the low melting point metal and the low melting point metal is melted, and fluctuations in fusing characteristics can be prevented. In addition, the fusible conductor pieces 31A and 32A quickly melt at a temperature below the melting point of the refractory metal by melting the refractory metal by melting the low melting point metal even when fusing. Can be melted.

In the protection element 1, all the soluble conductor pieces 31A and 32A are formed in the same shape, and the same number of the soluble conductor pieces 31A and 32A are formed of the first soluble conductor 31 and the second soluble conductor 32. Alternatively, the soluble conductor piece 31A and the soluble conductor piece 32A may have different shapes, sizes, and numbers. Further, the protection element 1 may have a different shape or size among the plurality of soluble conductor pieces 31A, or may have a different shape or size among the plurality of soluble conductor pieces 32A. In addition, the protective element 1 may be formed of only one of the first and second soluble conductors 31 and 32 with a soluble conductor piece, or may be soluble with the first and second soluble conductors 31 and 32. The conductor pieces 31A and 32A may be used in combination. The protection element 1 changes the resistance value of each soluble conductor piece 31A, 32A for each place by appropriately changing the size and number of each soluble conductor piece 31A, 32A, and the first and second soluble elements The order of fusing of the conductors 31 and 32, or the order and speed of fusing of each soluble conductor piece in the plurality of soluble conductor pieces 31A and 32A can be adjusted.

[Circuit board]
Next, the circuit board 2 on which the protection element 1 is mounted will be described. As the circuit board 2, for example, a known insulating substrate such as a rigid substrate such as a glass epoxy substrate, a glass substrate, or a ceramic substrate, or a flexible substrate is used. Further, as shown in FIG. 1B, the circuit board 2 has a mounting portion on which the protective element 1 is surface-mounted by reflow or the like, and is provided on the back surface 10f of the insulating substrate 10 of the protective element 1 in the mounting portion. Connection electrodes connected to the external connection terminals 11a, 12a, and 19a are provided. The circuit board 2 is mounted with an element such as an FET that energizes the heating element 14 of the protection element 1.

[Usage of circuit module]
Next, a method for using the protection element 1 and the circuit module 3 in which the protection element 1 is surface-mounted on the circuit board 2 will be described. As shown in FIG. 22, the circuit module 3 is used as a circuit in a battery pack of a lithium ion secondary battery, for example.

For example, the protection element 1 is used by being incorporated in a battery pack 40 having a battery stack 45 composed of battery cells 41 to 44 of a total of four lithium ion secondary batteries.

The battery pack 40 includes a battery stack 45, a charge / discharge control circuit 50 that controls charging / discharging of the battery stack 45, a protection element 1 to which the present invention that cuts off charging when the battery stack 45 is abnormal, and each battery cell A detection circuit 46 that detects the voltages 41 to 44 and a current control element 47 that controls the operation of the protection element 1 according to the detection result of the detection circuit 46 are provided.

The battery stack 45 is formed by connecting battery cells 41 to 44 that need to be controlled for protection from overcharge and overdischarge states, and is detachable through the positive terminal 40a and the negative terminal 40b of the battery pack 40. Are connected to the charging device 55, and the charging voltage from the charging device 55 is applied. The electronic device can be operated by connecting the positive terminal 40a and the negative terminal 40b of the battery pack 40 charged by the charging device 55 to the electronic device operated by the battery.

The charge / discharge control circuit 50 includes two current control elements 51 and 52 connected in series to a current path flowing from the battery stack 45 to the charging device 55, and a control unit 53 that controls operations of these current control elements 51 and 52. Is provided. The current control elements 51 and 52 are configured by, for example, field effect transistors (hereinafter referred to as FETs), and control the gate voltage by the control unit 53 to control conduction and interruption of the current path of the battery stack 45. . The control unit 53 operates by receiving power supply from the charging device 55, and controls the current so that the current path is interrupted when the battery stack 45 is overdischarged or overcharged according to the detection result by the detection circuit 46. The operation of the elements 51 and 52 is controlled.

Protective element 1 is connected, for example, on a charge / discharge current path between battery stack 45 and charge / discharge control circuit 50, and its operation is controlled by current control element 47.

The detection circuit 46 is connected to the battery cells 41 to 44, detects the voltage values of the battery cells 41 to 44, and supplies the voltage values to the control unit 53 of the charge / discharge control circuit 50. The detection circuit 46 outputs a control signal for controlling the current control element 47 when any one of the battery cells 41 to 44 becomes an overcharge voltage or an overdischarge voltage.

The current control element 47 is composed of, for example, an FET, and when the voltage value of the battery cells 41 to 44 exceeds a predetermined overdischarge or overcharge state by a detection signal output from the detection circuit 46, the protection element 1 is operated to control the charge / discharge current path of the battery stack 45 to be cut off regardless of the switch operation of the current control elements 51 and 52.

In the battery pack 40 having the above configuration, the configuration of the protection element 1 will be specifically described.

First, the protection element 1 to which the present invention is applied has a circuit configuration as shown in FIG. That is, the protective element 1 is connected to the first and second soluble conductors 31 and 32, the first soluble conductor 31 and the second soluble conductor 32 connected in series via the heating element extraction electrode 16. In this circuit configuration, the heating element 14 melts the first and second soluble conductors 31 and 32 by energizing the generated heating element lead electrode 16 to generate heat. In the protection element 1, for example, the first and second soluble conductors 31 and 32 are connected in series on the charge / discharge current path, and the heating element 14 is connected to the current control element 47. The first electrode 11 of the protection element 1 is connected to the open end of the battery stack 45 via the external connection electrode 11a, and the second electrode 12 is connected to the positive terminal 40a side of the battery pack 40 via the external connection electrode 12a. Connected to the open end. The heating element 14 is connected to the charge / discharge current path of the battery pack 40 by being connected to the first and second fusible conductors 31 and 32 via the heating element lead-out electrode 16, and the second heating element The current control element 47 is connected via the body electrode 19 and the external connection electrode 19a.

In such a battery pack 40, when the heating element 14 of the protection element 1 is energized and generates heat, the first and second soluble conductors 31 and 32 are melted, and the wettability causes the heating element 14 on the heating element extraction electrode 16. (See FIGS. 2C and 2D). As a result, the protection element 1 can reliably cut off the current path by fusing the first and second fusible conductors 31 and 32. Further, since the first and second fusible conductors 31 and 32 are fused, the power supply path to the heating element 14 is also cut off, so that the heating of the heating element 14 is also stopped.

Further, in the battery pack 40, when an unexpected large current exceeding the rating of the protection element 1 flows on the charge / discharge path, the first and second fusible conductors 31 and 32 are fused by self-heating (Joule heat). By doing so, the current path can be cut off.

When the first and second fusible conductors 31 and 32 are melted, the protective element 1 is provided with the holding member 24 on the heating element extraction electrode 16. The amount of retention can be increased, and even when the soluble conductor increases in size as the rating is improved, the melt protrudes from the heating element extraction electrode 16 and between the first and second electrodes 11 and 12. It is possible to prevent short circuit.

In addition, the protective element 1 is configured such that the first and second soluble conductors 31 and 32 are connected to the heating element extraction electrode 16 so as to be separated from each other, thereby connecting one soluble conductor between the first and second electrodes. Since the volume of the soluble conductor on the heating element extraction electrode 16 is reduced as compared with the conventional protection element that is mounted across the heating element extraction electrode, the heating element 14 generates heat when the current is interrupted. The volume of the soluble conductor to be melted can be reduced, and the energization path between the first and second electrodes 11 and 12 can be quickly cut off.

Further, since the volume of the soluble conductor to be melted is reduced, the protective element 1 does not overflow the molten conductor from the heating element extraction electrode 16, and reliably between the first and second electrodes 11, 12. Can be cut off, and the insulation reliability after the turning off of the current can be improved (see FIGS. 2C and 2D).

Note that the protection element 1 to which the present technology is applied is not limited to use in a battery pack of a lithium ion secondary battery, but also in various applications that require interruption of a current path by an electrical signal, such as abnormal overheating of an IC. Of course, it is applicable.

1 protection element, 2 circuit board, 3 circuit module, 10 insulating substrate, 10a surface, 10b first side surface, 10c second side surface, 10d third side surface, 10e fourth side surface, 10f back surface, 11 first Electrode, 11a external connection electrode, 12 second electrode, 12a external connection electrode, 14 heating element, 15 insulating member, 16 heating element extraction electrode, 18 first heating element electrode, 19 second heating element electrode, 19a external Connection electrode, 20 case, 21 side, 21a corner, 22 top surface, 24 holding member, 25 connection material, 26 slit, 27 opening, 28 base, 29 ridge, 31 first soluble conductor, 32nd 2 soluble conductors, 40 battery packs, 41 to 44 battery cells, 45 battery stacks, 46 detection circuits, 47 current control elements 50 charging and discharging control circuit, 51 a current control device, 53 control unit, 55 charging device

Claims (16)

1. An insulating substrate;
   First and second electrodes provided on the insulating substrate;
   A heating element formed on the insulating substrate;
   A heating element extraction electrode electrically connected to the heating element;
   A soluble conductor connecting the first and second electrodes via the heating element extraction electrode;
   A protective element provided on the heating element extraction electrode, and a holding member that wets and holds the molten material in which the soluble conductor is melted.
2. The protective element according to claim 1, wherein the holding member is mounted on the heating element extraction electrode.
3. A first fusible conductor mounted from the first electrode to the heating element extraction electrode;
   The protective element according to claim 1, further comprising a second soluble conductor mounted from the second electrode to the heating element extraction electrode.
4. The protection element according to claim 3, wherein the holding member is provided between the first soluble conductor and the second soluble conductor.
5. The protective element according to claim 1 or 2, wherein the holding member is subjected to a surface treatment that makes the melt of the soluble conductor easily spread.
6. The protective element according to claim 4, wherein the holding member is subjected to a surface treatment that makes the melt of the soluble conductor easily spread.
7. The holding member is connected to a prismatic body, a columnar body, a cylindrical body, a semi-cylindrical body, a spiral body, or the heating element extraction electrode that extends in the longitudinal direction of the heating element extraction electrode. The protection element according to claim 1 or 2, wherein the protection element is a rod-shaped body having a T-shaped cross section having a plate-like base portion and a protruding portion projecting from the base portion onto the heating element extraction electrode.
8. The holding member is connected to a prismatic body, a columnar body, a cylindrical body, a semi-cylindrical body, a spiral body, or the heating element extraction electrode that extends in the longitudinal direction of the heating element extraction electrode. The protective element according to claim 4, which is a rod-shaped body having a T-shaped cross section having a plate-like base portion and a protruding portion protruding from the base portion onto the heating element extraction electrode.
9. The protection element according to claim 7, wherein the holding member is formed with one or a plurality of penetrating or non-penetrating slits or one or a plurality of penetrating or non-penetrating openings extending in a direction substantially orthogonal to the longitudinal direction. .
10. The protective element according to claim 8, wherein the holding member is formed with one or a plurality of penetrating or non-penetrating slits or one or a plurality of penetrating or non-penetrating openings extending in a direction substantially orthogonal to the longitudinal direction. .
11. Instead of the first and second fusible conductors or together with the first and second fusible conductors, the plurality of first fusible conductor pieces and the second fusible conductor piece are each the heating element. The protective element according to claim 3, which is provided independently between the lead electrode.
12. Instead of the first and second fusible conductors or together with the first and second fusible conductors, the plurality of first fusible conductor pieces and the second fusible conductor piece are each the heating element. The protective element according to claim 4, which is provided independently between the lead electrode.
13. 4. The protective element according to claim 3, wherein each of the first and second soluble conductors has a laminated structure in which an inner layer is a low melting point metal layer and an outer layer is a high melting point metal layer.
14. The first and second soluble conductors or the first and second soluble conductor pieces each have a laminated structure in which an inner layer is a low melting point metal layer and an outer layer is a high melting point metal layer. Protection element.
15. The protective element according to claim 1 or 2, wherein the heating element and the heating element extraction electrode are superimposed.
16. A case covering the surface of the insulating substrate on which the soluble conductor is mounted;
    The protection element according to claim 1, wherein the holding member is provided in the case.

Images