WO2021039509A1 - Protection element and battery pack - Google Patents

Abstract

Provided is a protection element in which excess adhesive between fitting projections and fitting recesses is eliminated to reliably ensure the bonding strength between a lower case and an upper case.　The present invention includes: a fusible conductor 3; and a housing 6 having a lower case 4 and an upper case 5, the upper case 5 and the lower case 4 being bonded together with an adhesive to form the housing 6, wherein either the upper case 5 or the lower case 4 is provided with fitting recesses 25, the other is provided with fitting projections 26 to fit into the fitting recesses 25, and slits 27 continuous with the fitting recesses 25 and extending along a plane where the upper case 5 and the lower case 4 are in contact with each other are formed to allow an adhesive 19 to flow therethrough.

Description

Protective element, battery pack

This technology relates to a protective element that cuts off the current path and a battery pack that uses the protective element. This application claims priority on the basis of Japanese Patent Application No. Japanese Patent Application No. 2019-157431 filed on August 29, 2019 in Japan, and this application can be referred to in this application. It will be used.

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

In electronic devices that use many lithium-ion secondary batteries, the battery pack is overcharge-protected or over-discharged protected by turning the output on and off using the FET switch built into the battery pack. However, if the FET switch is short-circuited and broken for some reason, a lightning surge or the like is applied and a momentary large current flows, or the output voltage drops abnormally due to the life of the battery cell, or conversely, an excessive abnormal voltage occurs. The battery pack and electronic devices must be protected from accidents such as ignition even if the voltage is output. Therefore, in order to safely cut off the output of the battery cell in any such conceivable abnormal state, a protective element made of a fuse element having a function of cutting off the current path by an external signal is used. ..

As a protective element of a protection circuit for such a lithium ion secondary battery or the like, a structure is used in which a heating element is provided inside the protective element and the soluble conductor on the current path is melted by the heat generated by the heating element. ..

JP-A-2015-53260

The applications of lithium-ion secondary batteries have been expanding in recent years, and their use in applications with higher currents, such as electric tools such as electric drivers and transportation equipment such as hybrid cars, electric vehicles, and electrically power assisted bicycles, has been considered. Department recruitment has started. In these applications, a large current exceeding several tens of A to 100 A may flow, especially at the time of startup. It is desired to realize a protective element corresponding to such a large current capacity.

In order to realize a protective element that can handle such a large current, a protective element that uses a soluble conductor with an increased cross-sectional area and connects an insulating substrate with a heating element to the surface of the soluble conductor has been proposed. Has been done.

26, 27, 28, and 29 are diagrams showing a configuration example of a protective element assuming a large current application. 26 is an external perspective view, FIG. 27 is a plan view, FIG. 28 is a sectional view taken along line DD'in FIG. 27, and FIG. 29 is a plan view showing the upper case omitted. The protective element 100 shown in FIGS. 26 to 29 is said to have a soluble conductor 103 connected between the first and second external connection terminals 101 and 102 connected to an external circuit such as a battery charge / discharge circuit. It constitutes a part of an external circuit, and in the event of an abnormality such as overvoltage, the soluble conductor 103 melts to cut off the current path between the first external connection terminal 101 and the second external connection terminal 102. is there.

The protective element 100 includes an insulating substrate 105, first and second external connection terminals 101 and 102 connected to an external circuit, two heating elements 106 arranged in parallel on the surface of the insulating substrate 105, and a heating element 106. Solder over the insulating layer 107 to be coated, the surface electrode 108 laminated on the insulating layer 107 and connected to the heating element 106, the first external connection terminal 101, the surface electrode 108, and the second external connection terminal 102. It includes a soluble conductor 103 mounted via a paste.

In the protection element 100, the first and second external connection terminals 101 and 102 are arranged inside and outside the element housing, and are connected to a connection electrode provided on an external circuit board on which the protection element 100 is mounted by screwing or the like. By doing so, the soluble conductor 103 is incorporated into a part of the current path formed on the external circuit board.

The heating element 106 is a conductive member that generates heat when energized with a relatively high resistance value, and is made of, for example, nichrome, W, Mo, Ru, or a material containing these. Further, the heating element 106 is connected to the heating element feeding electrode 109 formed on the surface of the insulating substrate 105. The heating element feeding electrode 109 is connected to the third external connection terminal 110 via a solder paste. In the protection element 100, the third external connection terminal 110 is connected to the connection electrode provided on the external circuit board on which the protection element 100 is mounted, so that the heating element 106 is connected to the external power supply provided in the external circuit. It is connected. The heating element 106 is constantly controlled to energize and generate heat by a switch element or the like (not shown).

The heating element 106 is covered with an insulating layer 107 made of a glass layer or the like, and the surface electrode 108 is formed on the insulating layer 107, so that the surface electrode 108 is superimposed via the insulating layer 107. Further, on the surface electrode 108, a soluble conductor 103 connected between the first and second external connection terminals 101 and 102 is connected via a solder paste.

As a result, the protective element 100 is thermally connected by superimposing the heating element 106 and the soluble conductor 103, and when the heating element 106 generates heat by energization, the soluble conductor 103 can be melted.

The soluble conductor 103 is formed of a low melting point metal such as Pb free solder or a high melting point metal such as Ag, Cu or an alloy containing these as a main component, or has a laminated structure of a low melting point metal and a high melting point metal. Then, the soluble conductor 103 is connected from the first external connection terminal 101 to the second external connection terminal 102 across the surface electrode 108, so that the soluble conductor 103 is one of the current paths of the external circuit in which the protection element 100 is incorporated. Make up the part. Then, the soluble conductor 103 is melted by self-heating (Joule heat) when a current exceeding the rating is energized, or is blown by the heat generated by the heating element 106, and is between the first and second external connection terminals 101 and 102. To shut off.

Then, when the protection element 100 needs to cut off the current path of the external circuit, the heating element 106 is energized by the switch element. As a result, in the protection element 100, the heating element 106 is heated to a high temperature, and the soluble conductor 103 incorporated in the current path of the external circuit is melted. The melted conductor of the soluble conductor 103 is attracted to the highly wettable surface electrodes 108 and the first and second external connection terminals 101 and 102, so that the soluble conductor 103 is melted. Therefore, the protection element 100 can blow between the first external connection terminal 101 and the surface electrode 108 to the second external connection terminal 102 to cut off the current path of the external circuit.

As shown in FIG. 30, the protective element 100 has a lower case 111 and an upper case 112, and the lower case 111 and the upper case 112 are joined to each other to form a housing 113 of the protective element 100. To configure. 30 is a view showing the housing 113, (A) is a bottom view of the upper case 112, (B) is a cross-sectional view of the lower case 111 and the upper case 112, and (C) is a lower case 111. It is a plan view of. The lower case 111 supports the insulating substrate 105 and the first and second external connection terminals 101 and 102. The upper case 112 has a space for accommodating the above-described element internal configuration.

The lower case 111 has a fitting convex portion 114 formed at each corner portion. Further, the upper case 112 is formed with a fitting recess 115 that is fitted with the fitting convex portion 114 at each corner portion. When forming the housing 113, as shown in FIG. 31, the adhesive 120 is supplied to the side edge portion of the lower case 111 including the fitting convex portion 114, and is associated with the upper case 112. As a result, the fitting convex portion 114 and the fitting concave portion 115 are fitted via the adhesive 120, and the lower case 111 and the upper case 112 are joined.

Here, in order for the protective element 100 to be used for high current applications, it is required to increase the size of the soluble conductor 103 and the heating element 106 as described above. However, along with this, the thermal shock at the time of fusing the soluble conductor 103 also increases, and the air inside the case expands rapidly, so that the housing 113 is required to have a bonding strength that can withstand the pressure. In order to increase the bonding strength between the lower case 111 and the upper case 112, it is conceivable to increase the amount of the adhesive 120, but if the adhesive 120 is increased, it flows into the fitting recess 115 at the time of fitting. The amount increases. In addition, the adhesive also enters the fitting recess 115 along the fitting convex portion 114.

Therefore, as shown in FIG. 32, when the lower case 111 and the upper case 112 are butted against each other, there is no escape place for the adhesive 120 that has flowed in between the fitting convex portion 114 and the fitting concave portion 115. The adhesion between the lower case 111 and the upper case 112 is hindered. As a result, the upper case 112 floats from the lower case 111, and the upper case 112 comes off when the soluble conductor 103 is blown without obtaining the desired adhesive strength, or the predetermined housing height condition is satisfied. There is a risk of problems such as being unable to meet.

Therefore, the present technology eliminates the excess adhesive between the fitting convex portion and the fitting concave portion, and secures the adhesive strength between the lower case and the upper case, and a protective element using the protective element. The purpose is to provide a pack.

In order to solve the above-mentioned problems, the protective element according to the present technology has a soluble conductor, a lower case and an upper case, and is formed by joining the upper case and the lower case with an adhesive. The upper case and the lower case are provided with a fitting recess formed in one of them, and a fitting convex portion fitted in the fitting recess is formed in either one of the upper case and the lower case. A slit that is continuous with the joint recess and extends to the abutting surface of the upper case and the lower case to allow the adhesive to flow is formed.

In order to solve the above-mentioned problems, the protective element according to the present technology has a soluble conductor, a lower case and an upper case, and is formed by joining the upper case and the lower case with an adhesive. In the upper case and the lower case, one of the upper case and the lower case is formed with a fitting recess, and the other is formed with a fitting protrusion that fits into the fitting recess. The go-convex portion has a slit formed on the outer peripheral surface to allow the adhesive to flow.

In order to solve the above-mentioned problems, the protective element according to the present technology has a soluble conductor, a lower case and an upper case, and is formed by joining the upper case and the lower case with an adhesive. In the upper case and the lower case, one of the upper case and the lower case is formed with a fitting recess, and the other is formed with a fitting convex portion to be fitted to the fitting recess. A slit that is continuous with the joint recess and extends to the abutting surface of the upper case and the lower case to allow the adhesive to flow is formed, and the fitting convex portion is a slit that allows the adhesive to flow on the outer peripheral surface. Is formed.

Further, the battery pack according to the present technology includes one or more battery cells and a protective element connected to the charge / discharge path of the battery cell to block the charge / discharge path, and the protective element is a soluble conductor. It has a lower case and an upper case, and includes a housing formed by joining the upper case and the lower case with an adhesive, and the upper case and the lower case are either one of them. A fitting recess is formed in, and a fitting protrusion that fits in the fitting recess is formed in one of the fitting recesses, and is continuous with the fitting recess and extends to the butt surface of the upper case and the lower case. However, a slit for flowing the adhesive is formed.

Further, the battery pack according to the present technology includes one or more battery cells and a protective element connected to the charge / discharge path of the battery cell to block the charge / discharge path, and the protective element is a soluble conductor. It has a lower case and an upper case, and includes a housing formed by joining the upper case and the lower case with an adhesive, and the upper case and the lower case are either one of them. A fitting recess is formed in, a fitting protrusion that fits in the fitting recess is formed in one of the fitting protrusions, and the fitting protrusion is formed with a slit that allows the adhesive to flow along the protruding direction. Is what you are doing.

Further, the battery pack according to the present technology includes one or more battery cells and a protective element connected to the charge / discharge path of the battery cell to block the charge / discharge path, and the protective element is a soluble conductor. The upper case and the lower case are provided with a lower case and a housing formed by joining the upper case and the lower case with an adhesive, and the upper case and the lower case are either one of them. A fitting recess is formed in, and a fitting protrusion that fits in the fitting recess is formed in one of the fitting recesses, and is continuous with the fitting recess and extends to the butt surface of the upper case and the lower case. Then, a slit for flowing the adhesive is formed, and the fitting convex portion is formed with a slit for flowing the adhesive along the protruding direction.

According to the present technology, when the upper case and the lower case are butted against each other, the slit fits the excess adhesive by allowing the excess adhesive filled in the fitting recess to flow inside. Prevents it from staying in the fitting recess fitted with the protrusion. As a result, it is possible to prevent the adhesion between the upper case and the lower case from being hindered by the excess adhesive remaining in the fitting recess.

FIG. 1 is an external perspective view of a protective element to which the present technology is applied. FIG. 2 is a cross-sectional view of a protective element to which the present technology is applied. FIG. 3 is a plan view showing the upper case of the protective element to which the present technology is applied, omitting the upper case. FIG. 4 is a cross-sectional view showing a state in which the soluble conductor is melted in the protective element to which the present technology is applied. 5A and 5B are views showing a lower case, where FIG. 5A is a plan view and FIG. 5B is a sectional view taken along line EE'of FIG. 5A. 6A and 6B are views showing an upper case, where FIG. 6A is a bottom view and FIG. 6B is a cross-sectional view taken along the line CC'of FIG. 6A. 7A and 7B are views showing a joining process between the lower case and the upper case, FIG. 7A is a plan view of the lower case showing the flow of the adhesive, and FIG. 7B is a lower case coated with the adhesive. It is a GG'cross-sectional view of (A) which shows the flow of the adhesive in the state which the upper case is fitted. 8A and 8B are views showing a modified example of the concave slit, where FIG. 8A is a bottom view of the upper case and FIG. 8B is a sectional view taken along line HH'of FIG. 8A. FIG. 9 is a plan view showing a modified example of the concave slit. FIG. 10 is a plan view showing a modified example of the concave slit. 11A and 11B are views showing a joining process between the lower case and the upper case, FIG. 11A is a plan view showing the lower case coated with an adhesive, and FIG. 11B is a plan view showing the upper case and the lower case facing each other. It is a cross-sectional view of FF'arranged (A). 12A and 12B are views showing a housing provided with a convex slit in the lower case, FIG. 12A is a bottom view of the upper case, and FIG. 12B is a cross-sectional view in which the upper case and the lower case are arranged to face each other. (C) is a plan view of the lower case. 13A and 13B are views showing a fitting convex portion in which a convex portion slit is formed, where FIG. 13A is a plan view and FIG. 13B is a sectional view taken along line JJ'in FIG. 14A and 14B are views showing a housing provided with a convex slit in the lower case, FIG. 14A is a bottom view of the upper case, and FIG. 14B is a cross-sectional view in which the upper case and the lower case are arranged to face each other. (C) is a plan view of the lower case. 15A and 15B are views showing a fitting convex portion in which a convex portion slit is formed, FIG. 15A is a plan view, and FIG. 15B is a cross-sectional view taken along the line JJ'of FIG. 15A. 16A and 16B are views showing an upper case provided with a fitting convex portion, where FIG. 16A is a bottom view and FIG. 16B is a sectional view taken along line L-L'of FIG. 16A. 17A and 17B are views showing a lower case provided with a fitting recess, where FIG. 17A is a plan view and FIG. 17B is a sectional view taken along line MM'of FIG. 17A. 18A and 18B are views showing a joining process between the lower case and the upper case, FIG. 18A is a plan view of the lower case showing the flow of the adhesive, and FIG. 18B is a lower case coated with the adhesive. It is a KK'cross-sectional view of (A) which shows the flow | flow of an adhesive in the state which the upper case is fitted. 19A and 19B are views showing a joining process between the lower case and the upper case, FIG. 19A is a plan view showing the lower case coated with an adhesive, and FIG. 19B is a plan view showing the upper case and the lower case facing each other. It is the NN'cross-sectional view of (A) arranged. FIG. 20 is an external perspective view of the soluble conductor. FIG. 21 is a circuit diagram showing a configuration example of the battery pack. FIG. 22 is a circuit diagram of a protective element to which the present technology is applied. FIG. 23 is a cross-sectional view showing a modified example of the protective element to which the present technology is applied. FIG. 24 is a circuit diagram of a protective element according to a modified example. FIG. 25 is a cross-sectional view showing a state in which the soluble conductor is melted in the protective element according to the modified example. FIG. 26 is an external perspective view showing a protective element corresponding to a large current. FIG. 27 is a plan view of the protective element shown in FIG. 26. FIG. 28 is a cross-sectional view taken along the line DD'in FIG. 27. FIG. 29 is a plan view showing the protective element shown in FIG. 26 with the upper case omitted. FIG. 30 is a view showing a housing of the protective element shown in FIG. 26, (A) a bottom view of the upper case, (B) a cross-sectional view showing a state in which the lower case and the upper case are arranged facing each other, (C). ) Is a plan view of the lower case. 31A and 31B are views showing a joining process between the lower case and the upper case, FIG. 31A is a cross-sectional view showing a state in which the lower case and the upper case coated with an adhesive are arranged facing each other, and FIG. 31B is an adhesive. It is a top view of the lower case coated with. 32A and 32B are views showing a state in which the lower case and the upper case are joined, FIG. 32A is a bottom view showing the upper case in which the fitting recess is filled with an adhesive, and FIG. 32B is a bottom view showing the lower side. It is sectional drawing which shows the state which joined the case and the upper case.

Hereinafter, the protective element and battery pack to which this technology is applied will be described in detail with reference to the drawings. It should be noted that the present technology is not limited to the following embodiments, and it goes without saying that various changes can be made without departing from the gist of the present technology. In addition, the drawings are schematic, and the ratio of each dimension may differ from the actual one. Specific dimensions, etc. should be determined in consideration of the following explanation. In addition, it goes without saying that the drawings include parts having different dimensional relationships and ratios from each other.

[First Embodiment: Fitting recess slit]
FIGS. 1, 2 and 3 show the protection element 1 to which the present technology is applied. The protective element 1 includes an insulating substrate 2, a soluble conductor 3 mounted on the surface of the insulating substrate 2, a lower case 4 that supports the back surface of the insulating substrate 2, and an upper case 5 that covers the surface of the insulating substrate 2. The lower case 4 and the upper case 5 are joined by an adhesive 19 to provide a housing 6 for accommodating the insulating substrate 2. Further, the protection element 1 has first and second external connection terminals 7 and 8. The first and second external connection terminals 7 and 8 are arranged inside and outside the housing 6 and are connected to connection electrodes provided in an external circuit on which the protection element 1 is mounted by screwing or the like. The first and second external connection terminals 7 and 8 are supported by the lower case 4, and one end of each is connected by a soluble conductor 3. Then, the protective element 1 is incorporated into an external circuit via the first and second external connection terminals 7 and 8, so that the soluble conductor 3 forms a part of the current path of the external circuit, which will be described later. The current path can be cut off by fusing the heating element 10 due to heat generation or an overcurrent exceeding the rating.

[Insulated substrate]
The insulating substrate 2 is formed of, for example, an insulating member such as alumina, glass ceramics, mullite, and zirconia. In addition, the insulating substrate 2 may be made of a material used for a printed wiring board such as a glass epoxy board or a phenol substrate. In the insulating substrate 2 shown in FIG. 3, both side edges of the soluble conductor 3 connected via the surface electrode 11 described later in the extending direction are designated as the first side edge portion 2c, and the heating element electrode 15 and the heating element described later are used. Both side edges on which the feeding electrode 16 is formed are designated as the second side edge portion 2d.

[Heating element]
The heating element 10 that melts the soluble conductor 3 has a relatively high resistance value and is a conductive member that generates heat when energized. For example, nichrome, W, Mo, Ru, Cu, Ag, or these as main components. It consists of alloys and the like. These alloys, compositions, and powders of compounds are mixed with a resin binder or the like to form a paste, which is formed by forming a pattern on the surface 2a of the insulating substrate 2 using screen printing technology and firing the mixture. can do.

The heating element 10 is covered with an insulating layer 9 on the surface 2a of the insulating substrate 2. A surface electrode 11, which will be described later, is laminated on the insulating layer 9. The insulating layer 9 is provided to protect and insulate the heating element 10 and efficiently transfer the heat of the heating element 10 to the surface electrode 11 and the soluble conductor 3, and is made of, for example, a glass layer.

One end of the heating element 10 is connected to the heating element electrode 15 formed on the surface 2a of the insulating substrate 2. Further, the heating element electrode 15 is connected to the surface electrode 11 formed on the insulating layer 9. As a result, the heating element 10 is electrically connected to the soluble conductor 3 mounted on the surface electrode 11. The other end of the heating element 10 is connected to the heating element feeding electrode 16. The heating element feeding electrode 16 is formed on the surface 2a of the insulating substrate 2 and is connected to the third external connection terminal 17 via a connection material 20 such as solder paste, and is connected to the third external connection terminal 17 via the third external connection terminal 17. Is connected to an external circuit. Then, by connecting the protection element 1 to an external circuit, the heating element 10 is incorporated into the feeding path to the heating element 10 formed in the external circuit via the third external connection terminal 17.

Further, as shown in FIG. 3, the heating element 10 is formed so that the energizing direction intersects the energizing direction of the soluble conductor 3, and the heating element electrode 15 and the heating element feeding electrode 16 are on the second side. It is preferable that it is formed on the edge portion 2d in order to efficiently use the area of the insulating substrate 2.

Further, a plurality of heating elements 10 may be formed on the surface of the insulating substrate 2. In the example of the protection element 1 shown in FIG. 3, two heating elements 10 are formed. One end of each heating element 10 is connected to the heating element electrode 15, the other end is connected to the heating element feeding electrode 16, and they are electrically connected in parallel.

The protective element 1 may be formed inside the insulating layer 9 in which the heating element 10 is laminated on the surface 2a of the insulating substrate 2. Further, the protective element 1 may form the heating element 10 inside the insulating substrate 2. Further, the protective element 1 may form the heating element 10 on the back surface 2b of the insulating substrate 2. When the heating element 10 is formed on the back surface 2b of the insulating substrate 2, one end of the heating element 10 is connected to the back surface electrode formed on the back surface 2b of the insulating substrate 2 and penetrates between the back surface electrode and the front surface electrode 11. It is electrically connected to the soluble conductor 2 mounted on the surface electrode 11 through the conductive through hole. Further, the other end of the heating element 10 is connected to the third external connection terminal 17 via a heating element feeding electrode formed on the back surface 2b of the insulating substrate 2.

[Surface electrode]
On the insulating layer 9, a surface electrode 11 is formed which is connected to the heating element 10 via the heating element electrode 15 and is connected to the soluble conductor 3. The surface electrode 11 is connected to the soluble conductor 3 via a bonding material 20 such as solder paste. Further, in the surface electrode 11, when the soluble conductor 3 is melted, the molten conductor 3a is aggregated, whereby the soluble conductor 3 can be melted.

The surface electrode 11 may form a suction hole 12. When the soluble conductor 3 melts, the suction hole 12 sucks the molten conductor 3a by a capillary phenomenon and reduces the volume of the molten conductor 3a held on the surface electrode 11 (see FIG. 4). The protective element 1 increases the cross-sectional area of the soluble conductor 3 in order to cope with a large current application, so that even if the amount of melting increases, the protective element 1 is attracted to the suction hole 12 to increase the volume of the molten conductor 3a. Can be reduced. The insulating substrate 2 having such a configuration constitutes a fusing member 18 that melts the soluble conductor 3 by the heat when the heating element 10 is energized and generates heat, and sucks and shuts off the molten conductor 3a into the suction hole 12. To do.

As a result, the protective element 1 reduces the volume of the molten conductor 3a held on the surface electrode 11 to more reliably insulate between the first and second external connection terminals 7 and 8, and also provides a soluble conductor. It is possible to reduce the scattering of the molten conductor 3a due to the arc discharge generated at the time of fusing of 3 to prevent a decrease in insulation resistance, and further prevent a short-circuit failure due to adhesion of the soluble conductor 3 to a peripheral circuit at the mounting position. ..

A conductive layer 13 is formed on the inner surface of the suction hole 12. By forming the conductive layer 13, the suction hole 12 can easily suck the molten conductor 3a. The conductive layer 13 is formed of, for example, copper, silver, gold, iron, nickel, palladium, lead, tin, or an alloy containing any one as a main component, and the inner surface of the suction hole 12 is made of electrolytic plating or conductive paste. It can be formed by a known method such as printing. Further, the conductive layer 13 may be formed by inserting a plurality of metal wires or an aggregate of ribbons having conductivity into the suction holes 12.

Further, the suction hole 12 is preferably formed as a through hole penetrating in the thickness direction of the insulating substrate 2. As a result, the suction hole 12 can suck the molten conductor 3a to the back surface 2b side of the insulating substrate 2, suck more molten conductor 3a, and reduce the volume of the molten conductor 3a at the fusing portion. .. The suction hole 12 may be formed as a non-through hole.

The conductive layer 13 of the suction hole 12 is continuous with the surface electrode 11 formed on the surface 2a of the insulating substrate 2. Since the surface electrode 11 supports the soluble conductor 3 and the molten conductor 3a aggregates, the surface electrode 11 and the conductive layer 13 are continuous, so that the molten conductor 3a can be easily guided into the suction hole 12. ..

The conductive layer 13 and the surface electrode 11 are heated by the heating element 10 to facilitate suction of the molten conductor 3a of the soluble conductor 3 into the suction hole 12 and to easily aggregate on the surface electrode 11. be able to. Therefore, the protective element 1 promotes the action of sucking the molten conductor 3a from the surface electrode 11 into the suction hole 12 via the conductive layer 13, and can reliably melt the soluble conductor 3.

Further, the back surface electrode 14 connected to the conductive layer 13 of the suction hole 12 may be formed on the back surface 2b of the insulating substrate 2. The back surface electrode 14 is continuous with the conductive layer 13, so that when the soluble conductor 3 melts, the molten conductor 3a that has moved through the suction holes 12 aggregates (see FIG. 4). As a result, the protective element 1 can attract a larger amount of the molten conductor 3a and reduce the volume of the molten conductor 3a at the fusing portion.

The protective element 1 increases the number of paths for sucking the molten conductor 3a of the soluble conductor 3 by forming a plurality of suction holes 12, and sucks more molten conductors 3a to suck the molten conductor 3a at the fusing site. You may try to reduce the volume of. At this time, the plurality of suction holes 12 may be formed over the width direction of the soluble conductor 3 on which the surface electrode 11 and the soluble conductor 3 overlap. Further, the suction hole 12 may be formed in a region where the surface electrode 11 on which the molten conductor 3a wets and spreads and the soluble conductor 3 do not overlap.

Further, when two heating elements 10 are provided in parallel, the front electrode 11 and the back surface can be formed on both sides of the suction hole 12 regardless of whether they are formed on the front surface 2a, the back surface 2b or the inside of the insulating substrate 2. It is preferable for heating the electrode 14 and for sucking and aggregating more molten conductors 3a.

[Case]
Next, the housing 6 of the protection element 1 will be described. The housing 6 is formed by joining the lower case 4 and the upper case 5 with an adhesive 19. The housing 6 can be formed by using, for example, various engineering plastics, thermoplastics, ceramics, and other insulating members. Further, in the housing 6, the soluble conductor 3 expands spherically on the surface 2a of the insulating substrate 2 when melted, and the molten conductor 3a is placed on the surface electrodes 11 and the first and second external connection terminals 7 and 8. It has enough internal space to agglomerate.

The lower case 4 and the upper case 5 are joined using an adhesive 19. The adhesive 19 is supplied and cured between the upper end surface of the side wall of the lower case 4 and the lower end surface 5a of the side wall of the upper case 5 forming the side surface of the housing 6, so that the lower case 4 and the upper case 5 are formed. And are joined. The adhesive 19 is not particularly limited, and examples thereof include a thermosetting adhesive. The form of the adhesive 19 may be any form that exhibits fluidity in the bonding process, and its phase state does not matter, but it is preferably liquid from the viewpoint of workability.

Further, in the protective element to which the present technology is applied, the lower case 4 and the upper case 5 have a fitting recess 25 formed in one of them, and a fitting convex that fits in the fitting recess 25 in either one. A portion 26 is formed. In the following, a case where the fitting convex portion 26 is provided in the lower case 4 and the fitting concave portion 25 is provided in the upper case 5 will be described as an example.

[Lower case]
5A and 5B are views showing the lower case 4, FIG. 5A is a plan view, and FIG. 5B is a sectional view taken along line EE'of FIG. 5A. The lower case 4 is formed in a substantially rectangular shape, and a total of four fitting convex portions 26 are formed at each corner portion. The fitting convex portion 26 is formed in a columnar shape, but the shape of the fitting convex portion 26 may be a convex shape that fits with the fitting concave portion 25 described later, for example, a conical shape, a prismatic shape, a pyramidal shape, or the like. But it may be.

Further, the lower case 4 is provided with a concave surface portion 23 that holds the central portion of the insulating substrate 2 in a hollow shape at a substantially central portion. The lower case 4 supports the outer edge of the insulating substrate 2 along the side edge of the concave surface portion 23. By providing the concave surface portion 23, the contact area between the lower case 4 and the insulating substrate 2 can be reduced, and the heat of the heating element 10 can be suppressed from being absorbed by the lower case 4. Therefore, the protective element 1 can efficiently transfer the heat of the heating element 10 to the soluble conductor 3, and can melt the heating element more quickly. In particular, by providing the concave surface portion 23 in the substantially central portion of the lower case 4, the area directly below the heating element 10 is made hollow, and heat dissipation of the heating element 10 to the lower case 4 can be suppressed.

[Upper case]
6A and 6B are views showing the upper case 5, where FIG. 6A is a bottom view and FIG. 6B is a sectional view taken along line CC'of FIG. 6A. The upper case 5 is formed in a substantially rectangular shape like the lower case 4, and each corner is provided with a total of four fitting recesses 25 into which the fitting protrusions 26 provided on the lower case 4 are fitted. ing. Further, the upper case 5 covers the soluble conductor 3 formed on the surface 2a of the insulating substrate 2 and the first and second external connection terminals 7 and 8, and the fused soluble conductor 3a covers the surface electrode 11 and the surface electrode 11. It has an internal space that can be aggregated on the first and second external connection terminals 7 and 8.

Further, the upper case 5 is continuous with the fitting recess 25 and extends to the lower end surface 5a of the side wall of the upper case 5 which is the abutting surface of the upper case 5 and the lower case 4, and the recess slit 27 through which the adhesive 19 flows flows. Is formed. As shown in FIG. 7, when the upper case 5 and the lower case 4 are butted against each other, the recessed slit 27 is adhered by allowing a surplus of the adhesive 19 filled in the fitting recess 25 to flow inside. It prevents the excess of the agent 19 from staying in the fitting recess 25 fitted with the fitting convex portion 26. As a result, it is possible to prevent the adhesion between the upper case 5 and the lower case 4 from being hindered by the excess adhesive 19 staying in the fitting recess 25. Since the adhesive 19 required for joining the fitting convex portion 26 remains in the fitting concave portion 25, sufficient adhesive strength between the fitting concave portion 25 and the fitting convex portion 26 is ensured. .. Further, by providing the recessed slit 27, the adhesive area with the adhesive 19 is increased, and the adhesive strength can be improved.

Therefore, the protective element 1 can be brought into close contact with the lower case 4 without the upper case 5 floating, and a desired adhesive strength can be obtained. As a result, the protective element 1 can prevent problems such as the upper case 5 coming off when the soluble conductor 3 is blown, or the height condition of a predetermined housing not being satisfied.

The recessed slit 27 is preferably formed along the lower end surface 5a of the side wall of the upper case 5 to which the adhesive 19 is supplied. Further, the length of the recessed slit 27 is not particularly limited. The width of the recess slit 27 is not particularly limited, but is preferably equal to or less than the diameter of the fitting recess 25 in a plan view. The depth of the recess slit 27 is not particularly limited, but is preferably the same as or shallower than the depth of the fitting recess 25.

Further, as shown in FIG. 6B, the recess slit 27 is formed in a tapered shape that gradually becomes shallower from the bottom surface side of the fitting recess 25 to the upper surface side of the fitting recess 25 as it is separated from the fitting recess 25. It is preferable that it is. As a result, the excess adhesive 19 that has flowed into the recessed slit 27 is guided to the lower end surface 5a of the side wall of the upper case 5, which is the abutting surface of the upper case 5 and the lower case 4, and the upper case 5 and the lower case 4 are joined. Can be offered to. Further, the adhesive strength can be improved by relatively increasing the supply amount of the adhesive toward the corner portion of the housing 6.

Further, as shown in FIG. 8, the recess slit 27 may be formed so as to gradually widen as it is separated from the fitting recess 25. This makes it easier for the excess adhesive 19 to flow out from the fitting recess 25 to the slit tip.

Further, as shown in FIG. 9, a plurality of recess slits 27 may extend from one fitting recess 25. As a result, a larger amount of excess adhesive 19 can be discharged from the fitting recess 25. The shapes (width, length, depth, inclination, etc.) of the plurality of recessed slits 27 may be the same, and the flow amount of the adhesive 19 may be different depending on the direction by making them different.

Further, as shown in FIG. 9, it is preferable that the recess slit 27 is formed from one fitting recess 25 formed at each corner of the upper case 5 along two adjacent side walls. .. As a result, a larger amount of excess adhesive 19 can be discharged from the fitting recess 25. Further, as a result, the surplus of the adhesive 19 can be guided to the lower end surface 5a of the side wall of the upper case 5 which is the abutting surface with the lower case 4 and can be used for joining the upper case 5 and the lower case 4.

The recess slit 27 is preferably formed in all the fitting recesses 25, but it does not necessarily have to be formed in all the fitting recesses 25.

Further, as shown in FIG. 10, the recess slits 27 extending from the adjacent fitting recesses 25 may be formed so as to be continuous with each other. As a result, the surplus of the adhesive 19 filled in the fitting recess 25 is led out to the recess slit 27, and the surplus of the adhesive 19 supplied to the butt surfaces of the upper case 5 and the lower case 4 is recessed. It can be absorbed into the slit 27 to prevent the adhesion of the adhesive 19 from being hindered by the excess. Further, by providing the recessed slit 27, the adhesive area with the adhesive 19 is increased, and the adhesive strength can be improved.

The upper case 5 has first and second external connection terminals 7 and 8 and a third external connection terminal 17 supported by the lower case 4 on the lower end surface 5a of the side wall that is abutted against the lower case 4. A recess is formed for arranging the housing 6 inside and outside the housing 6. The recess is formed at a position corresponding to the arrangement position of the first and second external connection terminals 7, 8 and the third external connection terminal 17, and the recess is formed at a position corresponding to the arrangement position of the first and second external connection terminals 7, and the recess is the first and second external. It has a shape corresponding to the shapes of the connection terminals 7, 8 and the third external connection terminal 17. Therefore, in the housing 6, the lower case 4 and the upper case 5 are butted and joined without a gap, and the first and second external connection terminals 7 and 8 and the third external connection terminal 17 are moved out of the housing. It can be derived.

When forming the housing 6, as shown in FIG. 11, the adhesive 19 is supplied to the side edge portion of the lower case 4 including the fitting convex portion 26, and is associated with the upper case 5. As a result, the fitting convex portion 26 and the fitting concave portion 25 are fitted via the adhesive 19, and the lower case 4 and the upper case 5 are joined.

[Modification 1]
Next, a modified example of the protective element to which the present technology is applied will be described. The protective element to which this technique is applied forms a convex slit 28 in the fitting convex portion 26 in place of the concave slit 27 continuous with the fitting concave 25 or together with the concave slit 27 continuous with the fitting concave 25. You may. The convex slit 28 is provided on the peripheral surface of the fitting convex portion 26, and by flowing the surplus of the adhesive 19, the excess of the adhesive 19 prevents the lower case 4 and the upper case 5 from adhering to each other. To prevent.

The convex slit 28 is formed on the outer peripheral surface of the fitting convex portion 26. For example, as shown in FIGS. 12 and 13, the convex slit 28 is linear along the protruding direction of the fitting convex portion 26. It is formed. 12A and 12B are views showing a housing 6 in which a convex slit 28 is provided in the lower case 4. FIG. 12A is a bottom view of the upper case 5, and FIG. 12B faces the upper case 5 and the lower case 4. The arranged cross-sectional view (C) is a plan view of the lower case 4. 13A and 13B are views showing a fitting convex portion 26 in which a convex portion slit 28 is formed, where FIG. 13A is a plan view and FIG. 13B is a sectional view taken along line JJ'in FIG.

The shape of the convex slit 28 is not limited to a straight line, but may be a wave shape, a rectangular wave shape, a zigzag shape, or the like. Further, the convex slit 28 may be formed in the protruding direction of the fitting convex portion 26, or may be formed in the direction of orbiting the outer peripheral surface. Further, the convex slit 28 may be formed in a spiral shape on the outer peripheral surface of the fitting convex portion 26. Further, the convex slits 28 may be formed continuously or intermittently.

The direction in which the convex slit 28 is formed is not particularly limited, but it is preferably formed toward the abutting surface between the lower case 4 and the upper case 5 to which the adhesive 19 is supplied. For example, in the configuration shown in FIG. 12, the convex slit 28 is preferably formed in a direction along the side wall of the lower case 4. As a result, the surplus of the adhesive 19 can be flowed to the abutting surface between the lower case 4 and the upper case 5 to which the adhesive 19 is supplied, and can be used for adhesion. Further, when the recess slit 27 continuous with the fitting recess 25 described above is provided, it is preferable to form the recess slit 27 in the same direction as the recess slit 27.

Further, the convex slit 28 is preferably formed from the base of the fitting convex 28. Since the base of the fitting convex portion 26 is the abutting surface between the lower case 4 and the upper case 5, the adhesion can be promoted by positively absorbing the excess of the adhesive 19. Further, the convex slit 28 is preferably formed over the top of the fitting convex 28. As a result, the excess amount of the adhesive 19 staying in the fitting recess 25 can be easily introduced into the convex slit 28, and the absorption amount of the adhesive 19 can be increased.

Further, a plurality of convex slits 28 may be formed in one fitting convex portion 26. As a result, a larger amount of excess adhesive 19 can be absorbed into the convex slit 28. Further, as shown in FIG. 12, the convex slit 28 is preferably formed in a direction along two adjacent side walls of the fitting convex portion 26 formed at the corner portion of the lower case 4. As a result, the surplus of the adhesive 19 can be flowed to the abutting surface between the lower case 4 and the upper case 5 to which the adhesive 19 is supplied, and can be used for adhesion. Further, when the recess slit 27 continuous with the fitting recess 25 described above is provided, it is preferable to form the recess slit 27 in the same direction as the recess slit 27.

Further, as shown in FIGS. 14 and 15, the convex slit 28 may be formed in a tapered shape in which the width gradually decreases from the peripheral surface of the fitting convex portion 26 toward the center in a plan view. As a result, the capillary phenomenon can be allowed to flow, and the adhesive 19 can flow into the convex slit 28, and the inflow amount can be increased.

Further, the convex slit 28 may be formed in a tapered shape that gradually widens from the top to the base of the fitting convex portion 26 in a cross-sectional view. As a result, the capillary phenomenon is allowed to act, and the excess adhesive 19 staying on the abutting surface between the lower case 4 and the upper case 5 can flow into the convex slit 28, and the inflow amount is increased. Can be done.

In the protective element 1 shown in FIGS. 12 and 14, a convex slit 28 is provided in the fitting convex portion 26 formed in the lower case 4, and is fitted with the fitting concave portion 25 formed in the upper case 5. A recess slit 27 continuous with the fitting recess 25 may be formed in the upper case 5. By forming the recessed slit 27 continuous with the fitting recess 25 together with the convex slit 28 continuous with the fitting convex portion 26, a larger excess of the adhesive 19 is absorbed, and the surplus of the adhesive 19 is used. It is possible to prevent the lower case 4 and the upper case 5 from being in close contact with each other.

[Modification 2]
In the above-described embodiment, the configuration in which the fitting recess 25 and the recess slit 27 are formed in the upper case 5 and the configuration in which the fitting convex portion 26 and the convex slit 28 are formed in the lower case 4 have been described. As shown in FIGS. 16 and 17, the protective element to which the technique is applied forms the above-mentioned fitting convex portion 26 in the upper case 51, and forms the above-mentioned fitting recess 25 and recess slit 27 in the lower case 52. You may. In the following description, the same configuration as that of the protection element 1 described above will be designated by the same reference numerals and details thereof will be omitted.

FIG. 18 shows a process of joining the upper case 51 and the lower case 52 to form the protective element 50. 16A and 16B are views showing an upper case 51 provided with a fitting convex portion 26, where FIG. 16A is a bottom view and FIG. 16B is a sectional view taken along line L-L'of FIG. 16A. 17A and 17B are views showing a lower case 52 provided with a fitting recess 25, where FIG. 17A is a plan view and FIG. 17B is a sectional view taken along line MM'of FIG. 17A. As shown in FIG. 17, the protective element 50 has the above-mentioned fitting recess 25 and recess slit 27 formed in the lower case 52.

The joining process between the lower case 52 and the upper case 51 is the same as that of the protective element 1 described above. That is, as shown in FIGS. 19A and 19B, the adhesive 19 is supplied along the abutting surface of the lower case 52 with the upper case 51. At this time, the adhesive 19 is supplied onto the fitting recess 25 and the recess slit 27 formed in each corner of the lower case 52. Then, as shown in FIG. 18, when the fitting convex portion 26 formed in the upper case 51 is inserted into the fitting recess 25 and the lower case 52 and the upper case 51 are brought into contact with each other, the fitting recess 25 is formed. It is possible to prevent the excess adhesive 19 filled therein from flowing out to the recess slit 27 and staying in the fitting recess 25. As a result, it is possible to prevent the adhesion between the upper case 51 and the lower case 52 from being hindered by the excess adhesive 19 staying in the fitting recess 25. Further, by providing the recessed slit 27, the adhesive area with the adhesive 19 is increased, and the adhesive strength can be improved.

[Modification 3]
Further, the protective element 50 is also formed in the upper case 51 in place of the recess slit 27 continuous with the fitting recess 25 formed in the lower case 52, or together with the recess slit 27 continuous with the fitting recess 25. The above-mentioned convex slit 28 may be formed in the fitting convex portion 26. Since the configurations of the concave slit 27 and the convex slit 28 are described in detail in the protective element 1, the details will be omitted. It goes without saying that the protective element 50 may also have various forms of the concave slit 27 and the convex slit 28, as in the protective element 1.

[Soluble conductor]
Next, the soluble conductor 3 will be described. The soluble conductor 3 is mounted between the first and second external connection terminals 7 and 8, and is fused by self-heating (Joule heat) when the heating element 10 is energized or a current exceeding the rating is energized. , The current path between the first external connection terminal 7 and the second external connection terminal 8 is cut off.

The soluble conductor 3 may be a conductive material that melts due to heat generated by the energization of the heating element 10 or in an overcurrent state. For example, in addition to SnAgCu-based Pb-free solder, BiPbSn alloy, BiPb alloy, BiSn alloy, etc. SnPb alloy, PbIn alloy, ZnAl alloy, InSn alloy, PbAgSn alloy and the like can be used.

Further, the soluble conductor 3 may be a structure containing a high melting point metal and a low melting point metal. For example, as shown in FIG. 20, the soluble conductor 3 is a laminated structure composed of an inner layer and an outer layer, and is a low melting point metal layer 31 as an inner layer and a high melting point metal layer as an outer layer laminated on the low melting point metal layer 31. It has 32. The soluble conductor 3 is connected to the first and second external connection terminals 7 and 8 and the surface electrode 11 via a bonding material 20 such as solder paste.

The low melting point metal layer 31 is preferably a metal containing solder or Sn as a main component, and is a material generally called "Pb-free solder". The melting point of the low melting point metal layer 31 does not necessarily have to be higher than the temperature of the reflow furnace, and may be melted at about 200 ° C. The high melting point metal layer 32 is a metal layer laminated on the surface of the low melting point metal layer 31, and is, for example, a metal containing Ag, Cu, or any of these as a main component, and is the first and second. It has a high melting point that does not melt even when the external connection terminals 7 and 8 and the surface electrodes 11 are connected to the soluble conductor 3 by reflow.

Such a soluble conductor 3 can be formed by forming a high melting point metal layer on a low melting point metal foil by using a plating technique, or using other well-known lamination techniques and film forming techniques. Can also be formed. At this time, the soluble conductor 3 may have a structure in which the entire surface of the low melting point metal layer 31 is covered with the high melting point metal layer 32, or may be a structure in which the entire surface is covered except for a pair of opposite side surfaces. The soluble conductor 3 may be composed of the high melting point metal layer 32 as an inner layer and the low melting point metal layer 31 as an outer layer, or three layers in which low melting point metal layers and high melting point metal layers are alternately laminated. It can be formed by various configurations such as the above-mentioned multi-layer structure, an opening is provided in a part of the outer layer to expose a part of the inner layer.

The soluble conductor 3 can be used even when the reflow temperature exceeds the melting temperature of the low melting point metal layer 31 by laminating the high melting point metal layer 32 as the outer layer on the low melting point metal layer 31 which is the inner layer. The shape can be maintained as the molten conductor 3, and the molten conductor 3 does not melt. Therefore, the protective element 1 can efficiently connect the first and second external connection terminals 7 and 8 and the surface electrode 11 to the soluble conductor 3 by reflow. Further, the protective element 1 does not melt at a predetermined temperature due to a local increase or decrease in resistance value due to deformation of the soluble conductor 3 due to reflow, or has a melting characteristic such as melting at a temperature lower than a predetermined temperature. Fluctuation of can be prevented.

Further, the soluble conductor 3 does not melt due to self-heating while a predetermined rated current is flowing. Then, when a current having a value higher than the rating flows, it melts due to self-heating and cuts off the current path between the first and second external connection terminals 7 and 8. Further, the soluble conductor 3 melts when the heating element 10 is energized and generates heat, and cuts off the current path between the first and second external connection terminals 7 and 8.

At this time, in the soluble conductor 3, the melted low melting point metal layer 31 erodes (solders) the high melting point metal layer 32, so that the high melting point metal layer 32 melts at a temperature lower than the melting temperature. Therefore, the soluble conductor 3 can be melted in a short time by utilizing the erosion action of the high melting point metal layer 32 by the low melting point metal layer 31. Further, since the molten conductor 3a of the soluble conductor 3 is separated by the physical pulling action of the surface electrode 11 and the first and second external connection terminals 7 and 8, the first is promptly and surely. , The current path between the second external connection terminals 7 and 8 can be cut off (FIG. 4).

Further, it is preferable that the soluble conductor 3 forms a volume of the low melting point metal layer 31 larger than the volume of the high melting point metal layer 32. The soluble conductor 3 is heated by self-heating due to an overcurrent or heat generated by the heating element 10, and the low melting point metal is melted to erode the high melting point metal, whereby the soluble conductor 3 can be rapidly melted and melted. Therefore, the soluble conductor 3 promotes this erosion action by forming the volume of the low melting point metal layer 31 larger than the volume of the high melting point metal layer 32, and promptly causes the first and second external connection terminals. It is possible to cut off between 7 and 8.

Further, since the soluble conductor 3 is formed by laminating the refractory metal layer 32 on the low melting point metal layer 31 which is the inner layer, the fusing temperature is significantly reduced as compared with the conventional chip fuse made of the refractory metal. can do. Therefore, the soluble conductor 3 can have a large cross-sectional area and can greatly improve the current rating as compared with a chip fuse or the like having the same size. In addition, it can be made smaller and thinner than conventional chip fuses having the same current rating, and is excellent in quick-melting property.

Further, the soluble conductor 3 can improve the resistance (pulse resistance) to a surge in which an abnormally high voltage is momentarily applied to the electric system in which the protection element 1 is incorporated. That is, the soluble conductor 3 must not be blown until, for example, a current of 100 A flows for several msec. In this respect, since a large current flowing in an extremely short time flows through the surface layer of the conductor (skin effect), the soluble conductor 3 is provided with a refractory metal layer 32 such as Ag plating having a low resistance value as an outer layer. , The current applied by the surge can easily flow, and fusing due to self-heating can be prevented. Therefore, the soluble conductor 3 can significantly improve the resistance to surges as compared with the conventional fuse made of a solder alloy.

The soluble conductor 3 may be coated with a flux (not shown) in order to prevent oxidation and improve the wettability at the time of fusing.

[Circuit configuration example]
As shown in FIG. 21, such a protective element 1 is incorporated and used in, for example, a circuit in a battery pack 33 of a lithium ion secondary battery. The battery pack 33 has, for example, a battery stack 35 composed of battery cells 34a to 34d of a total of four lithium ion secondary batteries.

The battery pack 33 includes a battery stack 35, a charge / discharge control circuit 36 that controls charging / discharging of the battery stack 35, and a protective element 1 to which the present invention is applied that cuts off the charging / discharging path when the battery stack 35 is abnormal. It includes a detection circuit 37 that detects the voltage of the battery cells 34a to 34d, and a current control element 38 that serves as a switch element that controls the operation of the protection element 1 according to the detection result of the detection circuit 37.

The battery stack 35 is formed by connecting battery cells 34a to 34d, which require control for protection from overcharge and overdischarge states, in series, and is detachable via the positive electrode terminals 33a and the negative electrode terminals 33b of the battery pack 33. Is connected to the charging device 29, and the charging voltage from the charging device 29 is applied. The battery pack 33 charged by the charging device 29 can operate the electronic device by connecting the positive electrode terminal 33a and the negative electrode terminal 33b to the electronic device operated by the battery.

The charge / discharge control circuit 36 is a control unit that controls the operation of two current control elements 39a and 39b connected in series to the current path between the battery stack 35 and the charging device 29, and the operations of these current control elements 39a and 39b. It includes 40. The current control elements 39a and 39b are composed of, for example, field effect transistors (hereinafter referred to as FETs), and by controlling the gate voltage by the control unit 40, the current path of the battery stack 35 moves in the charging direction and / or the discharging direction. Controls the continuity and interruption of the. The control unit 40 operates by receiving power supplied from the charging device 29, and controls the current so as to cut off the current path when the battery stack 35 is over-discharged or over-charged according to the detection result by the detection circuit 37. It controls the operation of the elements 39a and 39b.

The protection element 1 is connected on, for example, the charge / discharge current path between the battery stack 35 and the charge / discharge control circuit 36, and its operation is controlled by the current control element 38.

The detection circuit 37 is connected to the battery cells 34a to 34d, detects the voltage values of the battery cells 34a to 34d, and supplies each voltage value to the control unit 40 of the charge / discharge control circuit 36. Further, the detection circuit 37 outputs a control signal for controlling the current control element 38 when any one of the battery cells 34a to 34d becomes an overcharge voltage or an overdischarge voltage.

The current control element 38 is composed of, for example, an FET, and is a protection element when the voltage value of the battery cells 34a to 34d exceeds a predetermined over-discharged or over-charged state by the detection signal output from the detection circuit 37. 1 is operated to control the charge / discharge current path of the battery stack 35 so as to be cut off regardless of the switch operation of the current control elements 39a and 39b.

The protective element 1 to which the present invention is applied, which is used in the battery pack 33 having the above configuration, has the circuit configuration as shown in FIG. That is, in the protection element 1, the first external connection terminal 7 is connected to the battery stack 35 side, the second external connection terminal 8 is connected to the positive electrode terminal 33a side, whereby the soluble conductor 3 is connected to the battery stack 35. It is connected in series on the charge / discharge path. Further, in the protection element 1, the heating element 10 is connected to the current control element 38 via the heating element feeding electrode 16 and the third external connection terminal 17, and the heating element 10 is connected to the open end of the battery stack 35. To. As a result, one end of the heating element 10 is connected to one open end of the soluble conductor 3 and the battery stack 35 via the surface electrode 11, and the other end is connected to the current control element 38 via the third external connection terminal 17. And the other open end of the battery stack 35. As a result, a feeding path to the heating element 10 whose energization is controlled by the current control element 38 is formed.

[Operation of protective element]
When the detection circuit 37 detects an abnormal voltage of any of the battery cells 34a to 34d, it outputs a cutoff signal to the current control element 38. Then, the current control element 38 controls the current so as to energize the heating element 10. In the protection element 1, a current flows from the battery stack 35 to the heating element 10, whereby the heating element 10 starts to generate heat. In the protective element 1, the soluble conductor 3 is melted by the heat generated by the heating element 10, and the charge / discharge path of the battery stack 35 is blocked. Further, the protective element 1 is formed by containing the high melting point metal and the low melting point metal in the soluble conductor 3, so that the low melting point metal is melted before the melting of the high melting point metal, and the high melting point due to the melted low melting point metal. The soluble conductor 3 can be dissolved in a short time by utilizing the erosion action of the melting metal.

In the protective element 1, the heat generation of the heating element 10 is stopped because the feeding path to the heating element 10 is also blocked by the melting of the soluble conductor 3.

Note that the protective element 1 can cut off the charge / discharge path of the battery pack 33 by melting the soluble conductor 3 by self-heating even when an overcurrent exceeding the rating is applied to the battery pack 33.

Here, the protective element 1 has the lower case 4 and the upper case 5 of the housing 6 in close contact with each other and has a desired adhesive strength. Therefore, the protective element 1 can prevent the upper case 5 from coming off when the soluble conductor 3 is blown. Further, since the lower case 4 and the upper case 5 of the housing 6 are in close contact with each other, the protective element 1 can satisfy a predetermined height condition of the housing.

As described above, in the protective element 1, the soluble conductor 3 is melted by the heat generated by the energization of the heating element 10 or the self-heating of the soluble conductor 3 due to the overcurrent. At this time, the protective element 1 is a low melting point metal even when the soluble conductor 3 is exposed to a high temperature environment such as being reflow-mounted on the first and second external connection terminals 7 and 8 and the surface electrode 11. Has a structure coated with a refractory metal, so that deformation of the soluble conductor 3 is suppressed. Therefore, the fluctuation of the fusing characteristics due to the fluctuation of the resistance value due to the deformation of the soluble conductor 3 is prevented, and the fusing can be quickly performed by the predetermined overcurrent or the heat generated by the heating element 10.

The protective element 1 according to the present invention is of course applicable not only to the case of being used in a battery pack of a lithium ion secondary battery but also to various applications requiring interruption of a current path by an electric signal.

[Modification example 4]
Next, another modification of the protective element to which the present technology is applied will be described. In the following description, the same components as those of the protection elements 1 and 50 described above may be designated by the same reference numerals and the details thereof may be omitted. As shown in FIG. 23, the protective element 60 according to the modified example may have the soluble conductor 3 sandwiched between a plurality of fusing members 18. In the protection element 60 shown in FIG. 23, the fusing member 18 is arranged on one surface and the other surface of the soluble conductor 3, respectively. FIG. 24 is a circuit diagram of the protection element 60. Each of the fusing members 18 arranged on the front surface and the back surface of the soluble conductor 3 has one end of the heating element 10 via the heating element electrode 15 and the surface electrode 11 formed on each insulating substrate 2. The other end of the heating element 10 is connected to a power source for heating the heating element 10 via the heating element feeding electrode 16 and the third external connection terminal 17 formed on each insulating substrate 2.

Further, as shown in FIG. 25, when the protective element 60 melts the soluble conductor 3 by the heat generated by the heating element 10, the heating elements of the fusing members 18 and 18 connected to both sides of the soluble conductor 3 are generated. 10 generates heat and heats from both sides of the soluble conductor 3. Therefore, the protective element 60 can quickly heat the soluble conductor 3 and melt it even when the cross-sectional area of the soluble conductor 3 is increased in order to cope with a large current application.

The protective element 60 also has a housing 6 similar to the protective elements 1 and 50 described above, and the lower case 4 or the upper case 5 has a fitting recess 25 and a recess slit 27, or a fitting convex portion 26 and a convex portion. The slit 28 is formed.

Further, the protective element 60 sucks the molten conductor 3a from both sides of the soluble conductor 3 into each suction hole 12 formed in the insulating substrate 2 of each fusing member 18. Therefore, the protective element 60 is attracted by the plurality of fusing members 18 even when the cross-sectional area of the soluble conductor 3 is increased and a large amount of the molten conductor 3a is generated in order to cope with a large current application, and the soluble conductor 3 is reliably soluble. The conductor 3 can be blown. Further, the protective element 60 can melt the soluble conductor 3 more quickly by sucking the molten conductor 3a by the plurality of fusing members 18.

Even when the protective element 60 uses a coating structure in which the low melting point metal constituting the inner layer is coated with the high melting point metal as the soluble conductor 3, the soluble conductor 3 can be rapidly melted. That is, the soluble conductor 3 coated with the refractory metal requires time to heat to a temperature at which the refractory metal in the outer layer melts even when the heating element 10 generates heat. Here, the protective element 60 includes a plurality of fusing members 18, and by simultaneously heating each heating element 10, the refractory metal in the outer layer can be quickly heated to the melting temperature. Therefore, according to the protective element 60, the thickness of the refractory metal layer constituting the outer layer can be increased, and the rapid fusing property can be maintained while further increasing the rating.

Further, as shown in FIG. 23, the protective element 60 preferably has a pair of fusing members 18 and 18 facing each other and connected to the soluble conductor 3. As a result, the protective element 60 can simultaneously heat the same portion of the soluble conductor 3 from both sides with the pair of fusing members 18 and 18 and suck the molten conductor 3a, so that the soluble conductor 3 can be sucked more quickly. Can be heated and melted.

Further, in the protective element 60, it is preferable that the surface electrodes 11 formed on the insulating substrates 2 of the pair of fusing members 18 and 18 face each other via the soluble conductor 3. As a result, the pair of fusing members 18 and 18 are connected symmetrically, so that the load applied to the soluble conductor 3 is not unbalanced at the time of reflow mounting and the like, and the resistance to deformation is improved. be able to.

In any case where the heating element 10 is formed on the front surface 2a and the back surface 2b of the insulating substrate 2, forming the heating element 10 on both sides of the suction hole 12 heats the front surface electrode 11 and the back surface electrode 14, and more. It is preferable for aggregating and sucking the molten conductor 3a of the above.

1 protective element, 2 insulating substrate, 2a front surface, 2b back surface, 2c first side edge part, 2d second side edge part, 3 soluble conductor, 3a molten conductor, 4 lower case, 5 upper case, 6 housing Body, 7 1st external connection terminal, 8 2nd external connection terminal, 9 insulating layer, 10 heating element, 11 front electrode, 12 suction hole, 13 conductive layer, 14 back electrode, 15 heating element electrode, 16 heating element Power supply electrode, 17 third external connection terminal, 18 fusing member, 20 bonding material, 25 fitting recess, 26 fitting convex part, 27 convex part slit 28 slit, 29 charging device, 31 low melting point metal layer, 32 high melting point Metal layer, 33 battery pack, 33a positive electrode terminal, 33b negative electrode terminal, 34 battery cell, 35 battery stack, 36 charge / discharge control circuit, 37 detection circuit, 38 current control element, 39 current control element, 40 control unit, 50 protection element , 60 protective elements, 100 protective elements

Claims (18)

1. Soluble conductor and
   It has a lower case and an upper case, and includes a housing formed by joining the upper case and the lower case with an adhesive.
   In the upper case and the lower case, a fitting recess is formed in one of them, and a fitting protrusion that fits in the fitting recess is formed in one of the other.
   A protective element that is continuous with the fitting recess and extends to the abutting surface of the upper case and the lower case to form a slit through which the adhesive flows.
2. The protective element according to claim 1, wherein the slit is formed in a tapered shape that gradually becomes shallower from the bottom surface side of the fitting recess to the upper surface side of the fitting recess as the slit is separated from the fitting recess.
3. The protective element according to claim 1 or 2, wherein the slit gradually widens as it is separated from the fitting recess.
4. The protective element according to claim 1 or 2, wherein a plurality of the slits extend from one fitting recess.
5. The fitting recess is formed in the corner portion of the upper case or the lower case.
   The protective element according to claim 4, wherein the slit is formed from one of the fitting recesses along two adjacent side walls of the housing.
6. The protective element according to claim 1 or 2, wherein the fitting recess is formed in all corners of the upper case or the lower case.
7. The protective element according to claim 1 or 2, wherein the width of the slit is equal to or less than the diameter of the fitting recess in a plan view.
8. The protective element according to claim 1 or 2, wherein slits extending from adjacent fitting recesses are continuous.
9. Soluble conductor and
   It has a lower case and an upper case, and includes a housing formed by joining the upper case and the lower case with an adhesive.
   In the upper case and the lower case, a fitting recess is formed in one of them, and a fitting protrusion that fits in the fitting recess is formed in one of the other.
   The fitting convex portion is a protective element having a slit formed on the outer peripheral surface for flowing the adhesive.
10. The protective element according to claim 9, wherein a plurality of the slits are formed in one of the fitting convex portions.
11. The protective element according to claim 9 or 10, wherein the slit is formed in a direction along the side wall of the housing on the peripheral surface of the fitting convex portion.
12. The fitting convex portion is formed at a corner portion of the upper case or the lower case.
    The protective element according to claim 11, wherein the slits are formed in directions along two adjacent side walls of the housing.
13. The protective element according to claim 9 or 10, wherein the slit is formed in a tapered shape in which the width gradually decreases from the peripheral surface of the fitting convex portion toward the center in a plan view.
14. The protective element according to 9 or 10, wherein the slit is formed in a tapered shape that gradually widens from the top to the base of the fitting convex portion in a cross-sectional view.
15. Soluble conductor and
    It has a lower case and an upper case, and includes a housing formed by joining the upper case and the lower case with an adhesive.
    In the upper case and the lower case, a fitting recess is formed in one of them, and a fitting protrusion that fits in the fitting recess is formed in one of the other.
    A slit is formed which is continuous with the fitting recess and extends to the abutting surface of the upper case and the lower case to allow the adhesive to flow.
    The fitting convex portion is a protective element having a slit formed on the outer peripheral surface for flowing the adhesive.
16. With one or more battery cells
    A protective element connected to the charge / discharge path of the battery cell and blocking the charge / discharge path is provided.
    The protective element is
    Soluble conductor and
    It has a lower case and an upper case, and includes a housing formed by joining the upper case and the lower case with an adhesive.
    In the upper case and the lower case, a fitting recess is formed in one of them, and a fitting protrusion that fits in the fitting recess is formed in one of the other.
    A battery pack that is continuous with the fitting recess and extends to the abutting surface of the upper case and the lower case to form a slit through which the adhesive flows.
17. With one or more battery cells
    A protective element connected to the charge / discharge path of the battery cell and blocking the charge / discharge path is provided.
    The protective element is
    Soluble conductor and
    It has a lower case and an upper case, and includes a housing formed by joining the upper case and the lower case with an adhesive.
    In the upper case and the lower case, a fitting recess is formed in one of them, and a fitting protrusion that fits in the fitting recess is formed in one of the other.
    The fitting convex portion is a battery pack in which a slit for flowing the adhesive is formed along the projecting direction.
18. With one or more battery cells
    A protective element connected to the charge / discharge path of the battery cell and blocking the charge / discharge path is provided.
    The protective element is
    Soluble conductor and
    It has a lower case and an upper case, and includes a housing formed by joining the upper case and the lower case with an adhesive.
    In the upper case and the lower case, a fitting recess is formed in one of them, and a fitting protrusion that fits in the fitting recess is formed in one of the other.
    A slit is formed which is continuous with the fitting recess and extends to the abutting surface of the upper case and the lower case to allow the adhesive to flow.
    The fitting convex portion is a battery pack in which a slit for flowing the adhesive is formed along the projecting direction.

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