JP2010146835A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack, in which a safety element is installed between one end face of an element battery and a protective circuit board with a molding resin filled in the inside, in which floating and dislocation of the safety element are suppressed at formation of molding by an insert molding so as to stably operate the safety element, and deformation of an insulating plate to insulate between the safety element and the battery is suppressed. <P>SOLUTION: The battery pack has an insulating plate 20, a PTC element, and the protective circuit board 40, arranged on a sealing lid 12 of an element battery and is covered with a resin molding part. An extension lead plate 35 is jointed to an element lead 33. This extension lead plate 35 has lead portions 35b, 35c of cross-sectional U-shape. Further, a lead portion 35d of tongue-piece shape is formed at the extension lead plate 35, and the lead portion 35d is arranged along the upper face of the insulating plate 20. The right-end portion 35e of the tongue piece is locked to a claw 21 of the insulating plate 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a unit cell and a battery pack including a protection circuit board and a safety element such as a PTC.

In recent years, as a power source for mobile devices such as a mobile phone, a battery pack including a unit cell such as a lithium battery, a protection circuit board, and a safety element such as a PTC is often used.
The configuration of the battery pack according to the conventional example will be described.
6 is an exploded perspective view and a cross-sectional view showing the configuration of the battery pack disclosed in Patent Document 1. FIG.

  As shown in this figure, a negative electrode terminal 113 is provided on one end face of a flat rectangular unit cell 110, and a protective circuit board 130 is disposed so as to cover the one end face. A PTC (Positive Temperature Coefficient) element 150, leads 161, 162, an insulating plate 170, and the like are interposed between the unit cell 110 and the protection circuit board 130.

  The PTC element 150 is composed of an element main body 151 and a pair of element electrodes 152 and 153 so as to sandwich the element main body 151, and one of the element electrodes 152 is connected to the negative electrode terminal 113 of the unit cell 110. The other element electrode 153 is connected to the lead 134 on the negative electrode side of the protective circuit board 130 via the lead 162. An insulating plate 170 is interposed between the PTC element 150 and the sealing lid 112 to insulate them. The PTC element 150 has a function of detecting a temperature and controlling a current.

A lead 161 is connected to the clad plate 114 on the sealing lid 112 in the unit cell 110, and the lead 161 is connected to the lead 133 on the positive electrode side of the protection circuit board 130.
On the protection circuit board 130, a protection circuit that performs power distribution control between the unit cell 110 and an external device is formed between the lead 133 and the lead 134.
A battery pack is formed by forming the molding 120 in such a core pack by insert molding.
JP 2005-346945 A

When manufacturing the battery pack as described above, the other element electrode 153 is connected to the lead 134 on the negative electrode side of the protective circuit board 130 via the lead 162 by spot welding. In some cases, a gap or space is formed between the insulating plate 170 and the insulating plate 170.
Further, when manufacturing the battery pack as described above, in the process of forming the molding 120 by insert molding, the element body 151 that is a safety element may be lifted from the insulating plate 170 by the pressure received from the insert resin. There is also a possibility that the safety element comes into contact with a mold (rotary pin) for insert molding.

In such a case, in the manufactured battery pack, the temperature detection function by the safety element is impaired, and it becomes difficult to accurately and stably perform temperature detection. It becomes a problem.
Further, when the element main body 151 is lifted, the insert resin comes into contact with and presses the insulating plate 170 during insert molding, so that the insulating plate 170 covers the safety valve 115 as shown in FIG. In such a case, the insulating plate 170 may be deformed to enter the recess.

  The present invention has been made to solve the above-described problem, and in a battery pack in which a safety element is mounted between one end surface of a unit cell and a protective circuit board and a mold resin is filled, molding is performed by insert molding. To prevent the safety element from being lifted or displaced, thereby enabling the safety element to operate stably, and suppressing deformation of the insulating plate that insulates the safety element from the unit cell. Objective.

  In order to achieve the above object, a battery pack according to the present invention is provided with a unit cell having an electrode terminal provided on one end surface, and an insulating plate, a safety element, and a protective circuit board are sequentially stacked on the one end surface. The mold resin was filled between the one end surface and the protective circuit board. The safety element includes a safety element body, a lead extending from the safety element body and connected to the electrode terminal, and a lead body extending from the safety element body and connected to the protection circuit board. The tongue piece extending along the insulating plate is formed on the lead body, and the tip of the tongue piece is locked to the claw portion formed on the insulating plate.

  Here, the “safety element” refers to various safety elements used for battery control including thermal elements such as PTC elements, NTC (Negative Temperature Coefficient) elements, and thermal fuse elements.

  In the battery pack according to the present invention, a lead connected to one terminal and a lead body connected to the protection circuit board are extended from the safety element. The lead body is provided with a tongue piece extending along the insulating plate, and the tip of the tongue piece is engaged with a claw portion formed on the insulating plate, so that one end surface of the unit cell Even when pressure is applied to the safety element when filling the molding resin between the protective circuit board and the protective circuit board, the tongue of the lead body does not lift from the insulating plate. Therefore, a stable temperature detection operation is performed without impairing the temperature detection performance of the safety element.

In particular, one end surface of the unit cell has a long shape, and the lead and the lead body extend from the safety element body in the longitudinal direction of the one end face, or the lead body is in the vicinity of the safety element body. In the case where the extending direction is changed to the protective circuit board direction, the effect of preventing the safety element from being lifted by applying the present invention is great.
In the present invention, when a safety valve is provided on one end surface of the unit cell, if the tongue piece is disposed so as to cover the safety valve via the insulating plate, the mold is not formed in the region covered by the tongue piece. Therefore, even if the thickness of the insulating plate is small, the insulating plate is not deformed. Since the thickness of the insulating plate can be reduced, the cost is reduced.

FIG. 1 is an exploded perspective view showing a configuration of a battery pack according to an embodiment of the present invention.
This battery pack 1 is configured by attaching a label 3 on the surface of a battery pack body 2.
For the sake of explanation, the direction indicated by the arrow X in the figure is upward, the direction indicated by the arrow Y is rightward, and the direction indicated by the arrow Z is forward.

1. Configuration of Pack Battery Main Body 2 The configuration of the pack battery main body 2 according to the embodiment will be described with reference to FIG.
As shown in FIG. 2, the battery pack body 2 includes a flat rectangular unit cell 10, and an insulating plate 20, a PTC element 30, and a protection circuit board 40 are arranged on a sealing lid 12 of the unit cell 10. The resin mold part 50 is covered and configured.

The unit cell 10 is a lithium ion secondary battery, and is formed by filling a flat rectangular parallelepiped outer can 11 made of an Al alloy with an electrode body and an electrolyte, and the opening of the outer can 11 is sealed with a sealing lid 12. Has been.
The sealing lid 12 is a long plate extending right and left. The upper surface of the sealing lid 12 is provided with a negative terminal 13 protruding from the center, a positive terminal 14 provided on the left side, and a safety valve 15 on the right side. Is provided.

A positive electrode lead 60 is connected to the positive electrode terminal 14 which is a clad plate on the sealing lid 12. The positive electrode lead 60 is formed in a U-shaped cross section and is connected to a positive electrode conductive land (not shown) provided on the lower surface of the protection circuit board 40.
FIG. 3 is an exploded perspective view showing a main part of the battery pack body 2.
The insulating plate 20 is a plate-like member formed of an insulating resin material so as to cover a region on the right side of the sealing lid 12 with respect to the negative electrode terminal 13 through an insulating seal 16 of a double-sided adhesive tape. The PTC element 30 is disposed on the insulating plate 20. Therefore, the PTC element 30 and the sealing lid 12 are insulated by the insulating plate 20.

A claw portion 21 is formed at the right end of the insulating plate 20 to lock a tongue piece formed on the element lead of the PTC element 30. The claw portion 21 is located on the right end of the sealing lid 12.
The PTC element 30 includes an element main body 31 and a pair of element leads 32 and 33 connected to the upper and lower surfaces of the element main body 31.
The element body 31 is made of a material having a positive temperature characteristic (resistance increases as the temperature rises), for example, a material obtained by adding a trace amount of rare earth to BaTiO ₃ in a block shape (in the example shown in FIG. 3, a flat cylindrical shape). ).

One element lead 32 is connected to the negative electrode terminal 13 via the element lead 34, and the element lead 33 and the extension lead plate 35 connected to the element lead 33 are connected to the negative electrode conductive land 41 of the protection circuit board 40. It is connected.
The element lead 32 includes a lead portion 32a that is joined to the upper surface of the element body 31 and extends leftward, and a lead portion 32b that is bent obliquely downward from the lead portion 32a and extends leftward. The element lead 34 includes a lead portion 34 a connected to the upper surface of the negative electrode terminal 13 and a lead portion 34 b that is bent obliquely upward from the lead portion 34 a and extends rightward. The lead portion 32b of the element lead 32 and the lead portion 34b of the element lead 34 are overlapped and joined.

The element lead 33 includes a lead portion 33 a that is bonded to the lower surface of the element body 31 and extends rightward. The extension lead plate 35 is joined to the lead portion 33 a and is bent into a U-shaped cross section in the vicinity of the element main body 31, and the extending direction is changed to the direction of the protection circuit board 40.
That is, the extended lead plate 35 includes a lead portion 35a that is overlapped and joined to the lower surface side of the lead portion 33a, a lead portion 35b that rises upward from the lead portion 35a, and a lead portion 35c that is folded forward from the lead portion 35b. The lead portion 35 c is joined to the negative electrode conductive land 41.

The extended lead plate 35 has a tongue-like lead portion 35 d that extends from the lead portion 35 a to the right along the upper surface of the insulating plate 20. The right end portion 35 e of the tongue piece is locked to the claw portion 21 of the insulating plate 20.
Each element lead 32 to 34 is formed of a conductive metal plate.
Here, the extension lead plate 35 and the positive electrode lead 60 are planar in the initial state, and the lead portion 35 c of the extension lead plate 35 is connected to the negative electrode conductive land 41 on the back surface of the protection circuit board 40, so After one end is connected to a positive electrode conductive land (not shown) on the back surface of the protection circuit board 40, the extension lead plate 35 and the positive electrode lead 60 are bent into a U-shaped cross section (U shape) as described above. Created.

On the lower surface side of the protection circuit board 40, a protection circuit is formed that protects the unit cell 10 by controlling power flow between the unit cell 10 and an external device. Further, three external terminals 42 are provided on the upper surface of the protection circuit board 40.
The resin mold part 50 is formed by low-temperature insert molding and is formed so as to cover the protection circuit board 40, but the window part 51 so that the external terminals 42 of the protection circuit board 40 are exposed to the outside. Is provided. A test window 52 is opened on the upper surface of the resin mold portion 50 and is closed with a label 53.

The molding resin constituting the resin mold portion 50 is also filled on the lower surface side of the protection circuit board 40, and the filled resin is an electronic component 43, a conductive land, and a conductive land disposed on the lower surface side of the protection circuit board 40. The PTC element 30 and the like are covered.
2. Method for Manufacturing Pack Battery FIGS. 4A to 4C are process diagrams showing a method for manufacturing the battery pack 2.

  As shown in FIG. 4A, the positive electrode lead 60 before being folded into a U-shape is welded to the positive electrode terminal 14 of the unit cell 10, and the insulating plate 20 is mounted on the sealing lid 12 via the insulating seal 16. To do. 4B, the PTC element 30 formed by joining the element lead 32, the element lead 33, the element lead 34, and the extension lead plate 35 before being folded into a U-shape to the element body 31 is insulated. Mount on the plate 20. At this time, the right end portion 35 e of the extension lead plate 35 is engaged with the claw portion 21 of the insulating plate 20. Then, the element lead 34 is welded to the negative electrode terminal 13.

Next, the positive electrode conductive land provided on the lower surface of the protection circuit board 40 and the positive electrode lead 60 are welded, and the negative electrode conductive land 41 and the lead portion 35c are welded, so that the element lead 35 and the positive electrode lead 60 are U-shaped. The core pack 17 shown in FIG.
And the resin mold part 50 is formed by performing low temperature insert molding (low temperature molding) with respect to this core pack 17. FIG. That is, the core pack 17 is placed in a mold having a space corresponding to the core pack 17 and the resin mold portion 50, and molten resin is injected.

The injected insert resin covers the upper surface of the protection circuit board 40 and fills the space between the protection circuit board 40 and the sealing lid 12 in the core pack 17 to form the resin mold portion 50.
FIG. 5 is a schematic cross-sectional view showing a portion where the core pack 17 is subjected to low temperature insert molding. In the figure, the resin mold portion 50 is formed by filling the shaded area with the insert resin.

As resin materials for insert molding of the resin mold portion 50, acrylonitrile butadiene styrene (ABS) resin, polyvinyl chloride (PVC) resin, polycarbonate (PC) resin polypropylene (PP) resin, polyethylene (PE) resin, polyamide (PA ) Resin, urethane resin and the like can be used.
By attaching the label 3 so as to surround the surface of the battery pack body 2 created as described above (see the white arrow in FIG. 1), the battery pack 1 is completed.

3. Effects of Pack Battery 1 Effects of the battery pack 1 having the above configuration will be described.
As shown in FIG. 5, in the core pack 17, in addition to the element lead 34 of the PTC element 30 being bonded to the negative electrode terminal 13 and the lead portion 35 c of the extension lead plate 35 being bonded to the negative electrode conductive land 41. The lead portion 35 d of the extension lead plate 35 is disposed along the upper surface of the insulating plate 20, and the right end portion 35 e of the extension lead plate 35 is locked to the claw portion 21 of the insulating plate 20. Even if the pressure by the insert resin is applied to the PTC element 30 at the time of insert molding, the extension lead plate 35 does not float from the insulating plate 20.

  That is, in the battery pack as shown in FIG. 6B of the conventional example, the lead 162 from the element electrode 153 of the PTC element 150 is bent in the direction of the protection circuit board 130 at the stage of the core pack before the insert molding. Although it is joined to the lead 134 of the substrate 130, the end portion of the element electrode 153 is not locked on the insulating plate 170, so that when the molding 120 is formed, the insert resin presses the PTC element 150. Thus, the lead 162 is bent, and the element electrode 153 is likely to be lifted from the insulating plate 170. In addition, as described above, there is a case where there is a gap or space between the PTC element 150 and the insulating plate 170 to be connected.

On the other hand, in this embodiment, even when the insert resin is pressed by the PTC element 30 to insert the extended lead plate 35 from the insulating plate 20 during insert molding, the claw portion 21 is positioned at the right end of the extended lead plate 35. 35e is pressed down, so that the extension lead plate 35 does not float from the insulating plate 20.
Accordingly, when connecting the lead plates, the PTC element 30 is hardly displaced during insert molding.

Further, since there is no undesired space under the PTC element 30, the temperature detection performance of the PTC element 30 is not impaired. Therefore, in the battery pack 1 manufactured by insert molding in the core pack 17, temperature detection is accurately and stably performed by the PTC element 30.
Further, in the insulating plate 20, in the region covering the safety valve 15, the extension lead plate 35 covers the insulating plate 20, so that the insert resin does not directly contact the insulating plate 20 during insert molding. Therefore, even if the thickness of the insulating plate 20 is small, there is no deformation that causes the insulating plate 20 to be recessed into the recess on the safety valve 15.

4). In the battery pack 1, the tongue piece is formed by joining the extension lead plate 35 to the element lead 33 in the PTC element 30, but the element main body 31 and the negative electrode conductive land 41 are connected to each other and the tongue piece The element lead having the above may be made of one metal plate.
Moreover, it does not specifically limit about the kind of unit cell, It can apply also to a nickel cadmium secondary battery, a nickel hydride secondary battery, etc.

In the battery pack 1, the insulating plate 20, the PTC element 30, and the protective circuit board 40 are disposed on the sealing lid 12, but the insulating plate, the PTC element, and the protective circuit board are provided on the side surface or the bottom surface of the outer can 11. Similarly, in this case, a similar effect can be obtained by providing a tongue piece on the element lead and locking it to the claw portion.
In the above embodiment, a flat rectangular lithium ion secondary battery has been described as an example of the unit cell 10. However, the present invention can also be applied to a cylindrical unit cell, for example, on the side surface of a cylindrical outer can or By providing an insulating plate, a PTC element, and a protection circuit board on the bottom surface, and providing a tongue piece on the element lead and locking it to the claw portion, the same effect can be obtained.

  In the above embodiment, the PTC element 30 is used as the safety element, but various battery control safety elements such as a thermal element such as an NTC element and a thermal fuse element can be used.

  The present invention is useful for realizing a highly reliable battery pack as a power source for a mobile device.

It is a perspective view which shows the structure of the battery pack 1 concerning embodiment. 3 is an exploded perspective view showing a configuration of a battery pack main body 2. FIG. 4 is an exploded perspective view showing a main part of the battery pack main body 2. FIG. 5 is a process diagram illustrating a method for manufacturing the battery pack main body 2. FIG. 4 is a schematic cross-sectional view showing a portion where low-temperature insert molding is performed on the core pack 17. FIG. It is a disassembled perspective view and sectional drawing which show the structure of the battery pack concerning a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pack battery 2 Pack battery main body 5 Core pack 11 Exterior can 12 Sealing lid 13 Negative electrode terminal 14 Positive electrode terminal 15 Safety valve 16 Insulation seal 17 Core pack 20 Insulation plate 21 Claw part 30 PTC element 31 Element main body part 32, 33 Element lead 34 element Lead 35 Extension lead plate 35e Right end portion of extension lead plate 40 Protection circuit board 41 Negative electrode conductive land 42 External terminal 43 Electronic component 50 Resin mold part 60 Positive electrode lead

Claims (4)

It has a unit cell provided with an electrode terminal on one end surface,
On the one end surface, an insulating plate, a safety element, and a protective circuit board are sequentially stacked and arranged,
A battery pack filled with a mold resin between the one end face and the protective circuit board,
The safety element includes a safety element body, a lead extending from the safety element body and connected to the electrode terminal, and a lead body extending from the safety element body and connected to the protection circuit board. Prepared,
In the lead body,
A tongue extending along the insulating plate is formed;
A battery pack, wherein a tip portion of the tongue piece is engaged with a claw portion formed on the insulating plate. The one end surface of the unit cell has an elongated shape, and the lead and the lead body extend from the safety element body in a longitudinal direction of the one end surface. Pack battery. The lead body is
The battery pack according to claim 1 or 2, wherein the battery pack is bent in the vicinity of the safety element body, and the extending direction is changed to the protective circuit board direction. A safety valve is provided on one end surface of the unit cell,
The battery pack according to claim 1, wherein the tongue piece is disposed so as to cover the safety valve via the insulating plate.

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