Method for producing a battery pack and a battery pack produced therein

Abstract

The tips of the lug portions of the board touches the bottom of the opening between the projecting portions and the step portions, when the upper mold and the lower mold are fit together with inserted. Thus the board is retained with positioning to the molds certainly. After molds are fit together with inserted as mentioned above, polyamide resin is injected into the molding space from a resin-material-injecting orifice provided on the upper mold.

Description

[0001] This application is based on Application No. 23360 filed in Japan on Jan. 31, 2002, the content of which is incorporated hereinto by reference.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a method for producing a battery pack used for power source of an electronic device, etc. and a battery pack produced therein.

[0003] Recently, a battery pack having a outer case of resin with a battery and a board mounting a protection circuit for preventing over-charging or over-discharging when charged or discharged is used for a device such as a mobile phone, etc.

[0004] In such battery pack, the battery and the board are mounted in the outer case composed of an upper case and lower case so as to be held conventionally. Recently, a low-temperature-mold resin is injected between the board and the battery or covers the battery, to form molded resin. Such method is employed for reducing the number of parts and improving manufacturing efficiency.

[0005] Further, recently, external input-output terminals connecting the battery pack with an external circuit are not provided with led outwardly from the battery pack by lead wires but are formed on one surface of the board so as to be exposed to outside, so that the battery pack is downsized.

[0006] On the other hand, generally, in manufacturing of the battery packs, the external input-output terminals should be positioned at the relative position against the outer case or the mold resin with accuracy. Thus, it is required that the board is retained with positioning against the battery previously when the low-temperature-mold resin is injected. Concretely, the board is retained with positioning by a resin holder interposed between the board and the battery before the resin is injected, then they are molded with the holder together. Such method is also employed conventionally.

[0007] However, in this method, the holder interposed between them interferes with the flow of the resin at injection, it is prone to occur an impaired flow of the resin. Thus, the battery pack that is molded with occurrence of the impaired flow of the resin may have cracks or pinholes in the inside or the outside of the mold resin. In such case, it may have a problem such that the airproof between the board and the battery to be molded by the mold resin might not be achieved sufficiently, or sufficient mechanical strength might not be achieved. Such problem can reduce yield.

[0008] On the other hand, reducing the injecting velocity of the resin or increasing temperature of the resin or injecting pressure can reduce the occurrence of the impaired flow of the resin. However, it may cause another problem, which is that manufacturing efficiency might be reduced, or the battery or the protection circuit might have damage.

[0009] Further, it is considered that employing resin material to be injected with low viscosity can reduce the occurrence of the impaired flow of the resin. However, there is not the material with low viscosity at injection and sufficient mechanical strength as mold resin for the finished product.

[0010] The present invention is devised to solve the above problems, and therefore, is aimed to at providing: a method for producing a battery pack with accuracy of positioning the external input-output terminals in high yield, without reducing of manufacturing efficiency, and without increasing the number of the components; and a battery pack produced therein.

SUMMARY OF THE INVENTION

[0011] To solve the above problems, in the method for producing a battery pack of the present invention a battery is retained in a battery-retaining portion provided in a mold, which has the battery-retaining portion and a board-retaining portion interposing a space between them; a board with external input-output terminals is retained in the board-retaining portion; mold material is injected into the space to mold.

[0012] In the method for producing a battery pack, the mold material is injected with retaining the board in the board-retaining portion, therefore it can prevent the deviation of positioning the board cause of flowing of the mold material. Thus, it is possible to mold with accuracy of positioning the board against the molded part, even without holder to retain the board against the battery as the conventional.

[0013] Accordingly, the method can produce a battery pack with accuracy of positioning the external input-output terminals without the occurrence of the impaired flow of the resin when injecting.

[0014] In the above method for producing a battery pack, it is preferable that the board-retaining portion is formed in an opening provided on each internal surface of upper and lower parts of the mold, and each side of the board is inserted in each opening of upper and lower parts so as to position the board to be retained. It can improve ease of producing and accuracy of positioning the board.

[0015] Further, in the above method for producing a battery pack, it is preferable that the mold material is injected from an injecting orifice provided at the position facing to the space. It can perform corner-to-corner injecting the mold material into the molding-material-injecting space efficiently.

[0016] In the above method, it is preferable that the mold material to be injected into the inside of the mold is polyamide resin, which has sufficient flowability even at low temperature (not more than 240° C. and under low pressure (around 0.5-1 MPa).

[0017] Furthermore, the battery pack of the present invention includes: a battery; a board having external input-output terminals, which are connected to the battery electrically; and resin member molded in a space interposed between the battery and the board so as to form an integral structure, wherein, the board is held to the battery by the resin. The battery pack can hold the board and the battery by resin without a holder between them, so that it is advantageous for weight and cost.

[0018] In addition, the resin can be flowed in smooth when molding, so that it can provide high quality without cracks and pinholes in its inside or outside.

[0019] The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a developed view of the internal components of the battery pack according to an embodiment of the invention.

[0021] FIG. 2 is an external illustration showing an oblique view of the battery pack.

[0022] FIG. 3 is an oblique view of the lower mold used for resin molding of the battery pack.

[0023] FIG. 4 is a cross-sectional view showing the providing relationship of the upper, lower mold, the battery, and the board when the resin molding of the battery pack is performed.

DETAILED DESCRIPTION OF THE INVENTION

[0024] (The Structure of Battery Pack 1)

[0025] The following description will describe a battery pack 1 according to an embodiment of the invention with FIG. 1 and FIG. 2. FIG. 1 is a developed view of the internal components of the battery pack 1. FIG. 2 is an external illustration showing an oblique view of the battery pack 1.

[0026] As shown in FIG. 1, in the battery pack 1, a board 30 is provided to face the surface, on which terminals 11, 12, etc. of a lithium-ion battery 10 are formed. As shown in FIG. 2, molded resin 20 is provided to be filled in the space between the lithium-ion battery 10 and the board 30, and to cover the board 30. But, external input-output terminals 31, 32, 33 are exposed to outside.

[0027] As shown in FIG. 1, the positive terminal 11, the negative terminal 12, a safety valve 13, etc. are formed on the surface in the side, which opposes the board, in the lithium-ion battery 10.

[0028] Actually, the positive terminal 11 is formed of a clad material plate of Al—Ni connected onto an outer case of Al.

[0029] In addition, the negative terminal 12 is a projecting terminal covered in its periphery by an insulator so as to be separated from the outer case electrically.

[0030] The safety valve 13 is provided to exhaust the internal gas when the internal pressure is greater than the predetermined threshold.

[0031] On the other hand, the board 30 is a resin board with a main surface, on which the external input-output terminals 31, 32, 33, etc are formed. The board 30 is formed in a rectangular shape with a substantially similar size to the surface of the lithium-on battery 10, which opposes to. A pair of lug portions 34 is provided at each pairs of the end portions on sides of the longitudinal direction.

[0032] As shown in a detail view of the drawing, a circuit portion 35 and terminals for connecting 36, 37 are provided on the surface opposite with the above surface, on which the external input-output terminals 31, 32, 33, etc. are formed.

[0033] A protection circuit for protecting the lithium-ion battery 10 from over-charging or over-discharging when charged or discharged, a breaker, etc are formed in the circuit portion 35. The circuit portion 35 and each of the external input-output terminals 31, 32, 33 are connected via holes opening in direction of thickness of the board 30.

[0034] As shown in FIG. 1, leads 41, 42, insulating paper 43, etc. are provided between the lithium-ion battery 10 and the board 30.

[0035] Both of the leads 41, 42 of them are formed in an L-shaped plate of Ni connecting the positive terminal 11 and the negative terminal 12 of the lithium-ion battery 10 with the terminals for connecting 36, 37 of the board. In addition, the leads 41, 42 are connected with the respective terminals 11, 12, 36, and 37 by spot welding.

[0036] Further, the insulating paper 43 is provided with inserted for insulating between the lead 42 connected with the negative terminal 12 and the outer case, which is positive electrode. In addition, the insulating paper 43 plays a role of a protect film preventing resin material from bursting the safety valve 13 (because the safety valve 13 is a very thin aluminum film), when the molded resin 20 is molded as described below. Furthermore, it also plays a role of a gas-exhausting path exhausting the gas toward the outside of the battery pack 1, if the internal pressure of the lithium-ion battery 10 rises and burst the safety valve 13 to open in the case that the safety valve 13 is covered.

[0037] As mentioned above, the external input-output terminals 31, 32, and 33 are exposed in the surface portion of the molded resin 20 (the portion covering the main surface of the board 30). The terminal 31 of them is a positive side terminal, and the terminal 32 is a negative side terminal. The battery pack 1 inputs or outputs its electric power to the external circuit via these terminals 31, 32.

[0038] Additionally, the terminal 33 is a so-called device type determining resistance terminal. It is provided so that the device side can determine the battery type when the battery pack 1 is attached to the device.

[0039] Further, the above lug portions 34 are exposed in the top surface and the bottom surface of the molded resin 20 toward up and down (the bottom surface side is not shown).

[0040] (Process of Molding The Molded Resin 20)

[0041] A process of molding the molded resin 20, which is one of the features of the method for producing the battery pack 1 of the embodiment, will be described with FIG. 3 and FIG. 4 below.

[0042] As shown in FIG. 3, a recess portion mountable the above lithium-ion battery 10 and the board 30, etc. Is formed in the lower mold 100 used for molding the molded resin 20.

[0043] A battery-retaining portion 130 in the inside surface of the recess portion is mountable the lithium-ion battery 10 with positioning.

[0044] Further, projections 111 and a step portion 112 are formed in region of inside surface of the recess portion with a space from the battery-retaining portion 130. An opening portions formed between the projections 111 and the step portion 112 mount the board 30 to retain with positioning in the inside of the mold 100.

[0045] In addition, the shape of the lower mold 100 is described with FIG. 3 as above, the upper mold 200 also has the shape with the opening formed between the projections 211 and the step portion 212 similarly.

[0046] A process of molding the molded resin 20 with such molds 100, 200 will be described with FIG. 4 below, FIG. 4 is a cross-sectional view showing a status mounting the lithium-ion battery 10 and the board 30 in the inside of the lower mold 100 and the upper mold 200.

[0047] First, the lithium-ion battery 10 and the board 30 are mounted with facing and connected each other in the lower mold 100, then the upper mold 200 and the lower mold 100 are fit together with inserted.

[0048] As shown in FIG. 4, when the upper mold 200 and the lower mold 100 are fit together with inserted, the tips of the lug portions 34 of the board 30 touches the bottom of the openings between the projecting portions 111, 211 and the step portions 112, 212. Thus the board 30 is retained with positioning to the molds 100, 200 certainly.

[0049] As mentioned above, after the upper mold 200 and the lower mold 100 are fit together with inserted, polyamide resin is injected into the molding space 110 (the space to form the molded resin 20) from a resin-material-injecting orifice 230 provided on the upper mold 100 (resin temperature: around 200-230° C., molding pressure: around 0.5-1 Mpa). Here, as shown in FIG. 4, resin-material-injecting orifice 230 is provided at the position facing to the space between the lithium-ion battery 10 and the board 30 so as to perform corner-to-corner injecting the resin into the molding space 110 efficiently.

[0050] The molded resin 20 is formed as mentioned above. The board 30 is also retained with sandwiched between the projecting portions 111, 211 and the step portions 112, 212 formed each inner surface of the lower mold 100 and the upper mold 200 when the polyamide resin is injected, so that it can prevent the occurrence of the positioning deviation against the molds 100, 200 even under pressure of resin injection.

[0051] Accordingly, in the above molding the molded resin 20, the molded resin 20 and the board 30 are positioned certainly.

[0052] In addition, the lithium-ion battery 10 and the board 30 are held without a holder, therefore the flow of the resin material is not interfered at molding. That is, this method can provide smooth flow of the resin without increasing temperature or pressure of the injected resin, and without reducing injecting velocity.

[0053] Thus, the battery pack 1 produced through the above processes can be obtained without cracks and pinholes in the molded resin 20 caused of the impaired flow of the resin. Further, high positioning accuracy of the external input-output terminals 31, 32, and 33 is achieved.

[0054] In addition, in this battery pack 1, it is not necessary to increase temperature or pressure of the injected resin for a smooth flow of the resin. Therefore, it can avoid a deleterious effect to the circuit portion 35 and the lithium-ion battery 10 caused of high heat or pressure. So that their performance does not reduce.

[0055] In this embodiment, the battery pack having one prismatic type lithium-ion battery inside is described as one example. However, the shape, type, the mount number of the battery, etc. are not restricted in this embodiment. For example, the invention can be applied to a battery pack having a plurality of cylindrical type nickel-cadmium batteries

[0056] Additionally, polyamide resin is employed as the material of the molded resin 20, however, insulating material cap able of insert molding at low temperature, under low pressure can be employed. For example, polyurethane resin can be employed as such material.

[0057] Furthermore, in the above embodiment, the opening is formed so as to hold the board 30 with the fixed projecting portions 111, 211 and step portions 112, 212, which are formed in the molds 100, 200, however, an opening (groove, recess, gap, etc.) to retain the board is not restricted in this shape.

[0058] Moreover, it should be appreciated that the projecting portion 111 may be actuated in up-and-down by a cylinder, etc. That is, the projecting portion 111 is actuated higher when the lithium-ion battery 10 and the board 30 are mounted into the lower mold 100, and is actuated relatively lower according to inserting the upper mold 200 so as to fit together. It can make the recess portion, which remains on the surface of the molded resin 20 in the battery pack, small. Thus, it can provide preferable quality of the appearance. However, in all cases, it is preferable that the projecting portions 111, 211 and the step portions 112, 212 are in a shape minimizing the interference to the flow of the injected resin.

[0059] In the method for producing a battery pack mentioned above, a battery is retained in a battery-retaining portion provided in a mold, which has the battery-retaining portion and a board-retaining portion interposing a space between them; a board with external input-output terminals is retained in the board-retaining portion; mold material is injected into the space to mold.

[0060] In this method, the mold material in injected with retaining the board in the board-retaining portion inside of the mold, therefore high positioning accuracy of the external input-output terminals can be achieved, and the occurrence of the impaired flow of the resin can be avoided.

[0061] In addition, the above battery pack includes: a battery; a board having external input-output terminals, which are connected to the battery electrically; and resin molded in a space interposed between the battery and the board so as to form an integral structure, wherein, the board is attached to the battery with the resin.

[0062] The battery pack can hold the board and the battery by resin without a holder between them, so that it is advantageous for weight and cost.

[0063] Additionally, the resin can be flowed in smooth when molding, it can provide high quality without cracks and pinholes in its inside or outside.

[0064] As this invention may be embodied in several forms without departing from the spirit of essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within meets and bounds of the claims, or equivalence of such meets and bounds thereof are therefore intended to be embraced by the claims.

Claims

1. A method for producing a battery pack comprising the steps of: a step for retaining a battery in a battery-retaining portion provided in a mold, which has the battery-retaining portion and a board-retaining portion interposing a space between them; a step for retaining a board with external input-output terminals in the board-retaining portion; and a step for injecting mold material into the space to mold.

2. The method according to claim 1, wherein the board-retaining portion is formed in an opening provided each internal surface of upper and lower parts of the mold, and each side of the board is inserted in each opening of upper and lower parts so as to position the board to be retained.

3. The method according to claim 2, wherein the opening of the board-retaining portion is formed in a gap between a projecting portion and a step portion, and each side of the board is inserted in each opening formed between the projecting portion and the step portion of upper and lower parts one side to another side so as to position the board to be retained.

4. The method according to claim 3, wherein the projecting portion and the step portion provided to the mold position the board.

5. The method according to claim 3, wherein the projecting portion actuated by a cylinder positions the board.

6. The method according to claim 5, wherein the projecting portion is actuated higher when the battery and the board are mounted. Into the mold, and is actuated lower according to inserting the mold.

7. The method according to claim 2, wherein the mold material is injected from an injecting orifice provided at the position facing to the space.

8. The method according to claim 1, wherein the mold material is polyamide resin.

9. The method according to claim 1, wherein the mold material is polyurethane resin.

10. The method according to claim 8, wherein the polyamide resin is injected to the space between the battery and the board with molding pressure 0.5-1 Mpa at temperature 200-230° C.

11. A battery pack comprising: a battery; a board having external input-output terminals, which are connected to the battery electrically; and resin member molded in a space interposed between the battery and the board so as to form an integral structure, wherein the board is held to the battery by the resin member.

12. The battery pack according to claim 11, wherein the board has a lug portion to be inserted into a board-retaining portion of a mold to be retained with positioning.

13. The battery pack according to claim 12, wherein the board is formed in a rectangular shape, and the lug portions are provided at a pair of the end portions on side of the longitudinal direction.

14. The battery pack according to claim 11, wherein a circuit portion is provided on the back of the board.

15. The battery pack according to claim 14, wherein the circuit portion has a protection circuit for protecting the battery from over-charging or over-discharging when charged or discharged.

16. The battery pack according to claim 11, wherein the board has terminals for connecting on its back, and the terminals for connecting are connected to the battery via leads.