Flexible PCB and busbar module

Abstract

To provide a flexible substrate and a bus bar module that can increase the moisture resistance of the joints between an electronic component and a conductor circuit while suppressing losses in manufacturing yield.SOLUTION: A flexible substrate 1 includes an electronic component 10, a base film 21, a conductor circuit 22, and a coverlay 23. The electronic component 10 has electrodes 12a, 12b. The conductor circuit 22 is formed on a second surface (vertically lower surface) 21b of the base film 21, and has a bonding region 30 where the electrodes 12a, 12b are bonded using a bonding material. The coverlay 23 covers at least a portion of the second surface (vertically lower surface) 22b of the conductor circuit 22, and has an opening 24a that exposes the bonding region 30 to the outside.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a flexible substrate and a bus bar module. [Background technology]

[0002] BACKGROUND ART Flexible substrates in which electronic components are mounted on flexible printed circuits (hereinafter abbreviated as FPCs) have been known.

[0003] In an FPC, a conductor circuit is formed on the surface of a base film, and at least a portion of the surface of the conductor circuit is covered with an insulating coverlay.

[0004] In such a configuration, when an electronic component is mounted on an FPC, electrodes or terminals of the electronic component are joined to the joining areas of the conductor circuits exposed to the outside through the openings in the coverlay using a joining material such as solder.

[0005] Patent Document 1 discloses a configuration in which, in a flexible substrate in which electronic components are mounted on an FPC, a resin is applied to an opening in a coverlay, and the opening is covered with a resin film.

[0006] With this configuration, the joint between the electronic component and the conductor circuit is covered with a resin film at the opening in the coverlay, improving the moisture resistance of the joint. The joint includes the electrode of the electronic component, the bonding material, and the bonding area of ​​the conductor circuit. Therefore, even if condensation occurs at the opening of the FPC, it is possible to prevent the electronic component from shorting out due to the condensed water. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2017-27831 Summary of the Invention [Problem to be solved by the invention]

[0008] However, when forming a resin film by applying a resin, it is generally difficult to control the film thickness. For example, when a thin resin film is formed, condensed water may penetrate into the joint between the electronic component and the conductor circuit, potentially causing a short circuit in the electronic component.

[0009] Therefore, when the moisture resistance of the joint is increased by applying a resin to form a resin film, there is a possibility that the yield during manufacturing will decrease. Therefore, further improvements are needed to increase the moisture resistance of the joint between the electronic component and the conductor circuit while suppressing the decrease in the yield during manufacturing.

[0010] The present invention has been made in view of the problems inherent in the conventional technology, and an object of the present invention is to provide a flexible substrate and a bus bar module that can improve the moisture resistance of the joints between electronic components and conductor circuits while suppressing a decrease in manufacturing yield. [Means for solving the problem]

[0011] A flexible substrate according to a first aspect of the present invention comprises an electronic component having an electrode, a base film, a conductor circuit formed on a vertically lower surface of the base film and having a first bonding area to which the electrode is bonded using a bonding material, and a coverlay covering at least a portion of the vertically lower surface of the conductor circuit and having a first opening exposing the first bonding area to the outside.

[0012] A busbar module according to a second aspect of the present invention includes a case to be assembled to a battery module having a plurality of unit cells, a busbar supported by the case and electrically connecting the positive and negative electrode terminals of adjacent unit cells among the plurality of unit cells, and a flexible substrate housed in the case. The flexible substrate has a stem portion and branch portions branching from the stem and folding back so as to intersect with the stem in a plan view and electrically connected to the busbar. The end portions of the branch portions include an electronic component having an electrode, a base film, a conductor circuit formed on a vertically lower surface of the base film and having a first bonding region and a second bonding region, a coverlay covering at least a portion of the vertically lower surface of the conductor circuit and having a first opening exposing the first bonding region to the outside and a second opening exposing the second bonding region to the outside, and a metal plate. The coverlay further covers a portion of the vertically lower surface of the base film excluding the region exposed to the outside through the first opening. The metal plate is provided on a vertically lower surface of the coverlay and surrounds the electronic component. In the first opening, the electrode is bonded to the first bonding area using a bonding material. In the second opening, one end of the metal plate is bonded to the second bonding area. The other end of the metal plate is bonded to the bus bar. The electronic component is electrically connected to the bus bar via the conductor circuit and the metal plate. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a flexible substrate and a bus bar module that can improve the moisture resistance of the joint between the electronic component and the conductor circuit while suppressing a decrease in yield during manufacturing. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a bottom view of a flexible substrate according to a first embodiment. [Figure 2] FIG. 2 is an end view taken along line II-II in FIG. [Figure 3]FIG. 3 is an end view of a flexible substrate according to a first modified example of the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating a state before electronic components are mounted on a flexible printed wiring board in a flexible substrate according to a second modified example of the first embodiment. [Figure 5] FIG. 5 is a diagram illustrating a state after electronic components have been mounted on a flexible printed wiring board in a flexible substrate according to a second modified example of the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view of a flexible substrate according to the second embodiment. [Figure 7] FIG. 7 is a cross-sectional view of a flexible substrate according to a modified example of the second embodiment. [Figure 8] FIG. 8 is a plan view of a bus bar module including a flexible substrate according to the third embodiment. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. [Figure 10] FIG. 10 is a diagram illustrating a state before a plurality of branch portions branching from a trunk portion of a flexible printed wiring board are folded back in a flexible substrate according to a third embodiment. [Figure 11] FIG. 11 is a diagram illustrating a state after a plurality of branch portions branching from the trunk portion of the flexible printed wiring board have been folded back in the flexible substrate according to the third embodiment. [Figure 12] FIG. 12 is a diagram illustrating a state before electronic components are mounted on the ends of the branches of the flexible printed wiring board in the flexible substrate according to the third embodiment. [Figure 13] FIG. 13 is a diagram illustrating a state after electronic components have been mounted on the ends of the branches of the flexible printed wiring board in the flexible substrate according to the third embodiment. [Figure 14] FIG. 14 is a plan view of a flexible substrate according to a modified example of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] The flexible substrates according to the first to third embodiments will be described in detail below with reference to the drawings. Note that the dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions. Furthermore, the same or similar symbols are used for the same functions and configurations, and their description will be omitted as appropriate.

[0016] [First embodiment] [Flexible PCB configuration] First, the configuration of a flexible substrate 1 according to this embodiment will be described. Fig. 1 is a bottom view of the flexible substrate 1. Fig. 2 is an end view taken along line II-II in Fig. 1. Note that Figs. 1 and 2 only show a portion of the flexible substrate 1 in order to clearly show the mounting location of an electronic component 10.

[0017] 1 and 2 corresponds to the longitudinal direction of the flexible substrate 1. The Y direction shown in FIGS. 1 and 2 corresponds to the width direction of the flexible substrate 1 and is perpendicular to the X direction. The Z direction shown in FIGS. 1 and 2 corresponds to the height direction of the flexible substrate 1 and is perpendicular to the X and Y directions. In this embodiment, the Z direction corresponds to the vertical direction.

[0018] It is also possible to make the X direction and Y direction correspond to the width direction and length direction of the flexible substrate 1, respectively.

[0019] The +X side and -X side shown in Figures 1 and 2 correspond to the front and rear, respectively, of the flexible substrate 1. The +Y side and -Y side shown in Figures 1 and 2 correspond to the left and right, respectively, of the flexible substrate 1 when facing the front of the flexible substrate 1. The +Z side and -Z side shown in Figures 1 and 2 correspond to the top and bottom, respectively, of the flexible substrate 1.

[0020] 1 and 2, the flexible substrate 1 includes an electronic component 10 and a flexible printed circuit board (hereinafter abbreviated as FPC) 20. The electronic component 10 has a main body 11 and electrodes 12a and 12b. The electronic component 10 is, for example, a fuse. However, the electronic component 10 is not limited to a fuse and may be a resistor, a capacitor, a coil, a semiconductor, or the like.

[0021] The main body 11 contains an element (not shown) therein. The element is electrically connected to an electrode 12a at one end (-X side) of the main body 11, and is electrically connected to an electrode 12b at the other end (+X side) of the main body 11. When the electronic component 10 is a fuse, the main body 11 contains a fuse resistor therein.

[0022] Electrodes 12a, 12b are joined to conductive circuit 22 of FPC 1 using a bonding material such as solder. Fillets 13a, 13b, each filled with bonding material, are formed at the locations where electrodes 12a, 12b are joined to conductive circuit 22 using the bonding material. Because electrodes 12a, 12b are electrically connected to conductive circuit 22 via fillets 13a, 13b, fillets 13a, 13b are also referred to as connection portions.

[0023] The FPC 20 is flexible and includes a base film 21, a conductor circuit 22, and a coverlay 23. The base film 21 is flexible and formed in a planar shape. The base film 21 is the substrate of the FPC 20 and defines the overall shape of the FPC 20. The base film 21 is formed of, for example, a polyimide resin with excellent heat resistance.

[0024] The base film 21 has a first surface 21a and a second surface 21b that extend along the longitudinal direction of the flexible substrate 1. The first surface 21a and the second surface 21b face in opposite directions. When the flexible substrate 1 is mounted on a product, the first surface 21a and the second surface 21b face upward (+Z side) and downward (-Z side) of the flexible substrate 1, respectively (see FIGS. 1 and 2). For this reason, the first surface 21a and the second surface 21b are also referred to as the vertically upper surface and the vertically lower surface, respectively.

[0025] The conductive circuit 22 is formed on the second surface 21b of the base film 21. Specifically, a pattern layer constituting the conductive circuit 22 is laminated on the base film 21 on the second surface 21b side of the base film 21 (see FIG. 2).

[0026] Conductive circuit 22 has first surface 22a and second surface 22b extending along the longitudinal direction of flexible substrate 1. First surface 22a and second surface 22b face in opposite directions. When flexible substrate 1 is mounted on a product, first surface 22a and second surface 22b face upward (+Z side) and downward (-Z side) of flexible substrate 1, respectively (see FIGS. 1 and 2). For this reason, first surface 21a and second surface 21b are also referred to as the vertically upper surface and vertically lower surface, respectively.

[0027] When conductive circuit 22 is laminated on base film 21, first surface 22a of conductive circuit 22 abuts against second surface 21b of base film 21. Conductive circuit 22 is also called a Cu pattern.

[0028] In this embodiment, conductor circuits 22 extend along the longitudinal direction of flexible substrate 1 at the location where electronic component 10 is mounted on FPC 20, but this is not limiting. Depending on the usage state of flexible substrate 1, conductor circuits 22 may extend in a direction other than the longitudinal direction of flexible substrate 1.

[0029] Conductive circuit 22 has pads 31 and 32. Pads 31 and 32 are physically separated from each other and form bonding area 30 of conductive circuit 22. Pad 31 is bonded to electrode 12a of electronic component 10. Pad 32 is bonded to electrode 12b of electronic component 10.

[0030] Coverlay 23 is an insulating protective film that covers second surface 21b of base film 21 and second surface 22b of conductor circuit 22, except for an area on second surface 21b of base film 21 and an area (bonding area 30) on second surface 22b of conductor circuit 22 that are exposed to the outside at opening 24a (described later) (see FIGS. 1 and 2). In this way, coverlay 23 is laminated on part of base film 21 and part of conductor circuit 22 on the side of second surface 21b of base film 21 and the side of second surface 22b of conductor circuit 22.

[0031] With this configuration, coverlay 23 covers at least a portion of second surface 22b of conductive circuit 22. As a result, a portion of conductive circuit 22 is insulated and protected by coverlay 23.

[0032] The coverlay 23 has a first surface 23a and a second surface 23b that extend along the longitudinal direction of the flexible substrate 1. The first surface 23a and the second surface 23b face in opposite directions. When the flexible substrate 1 is mounted on a product, the first surface 23a and the second surface 23b face upward (+Z side) and downward (-Z side) of the flexible substrate 1, respectively (see FIGS. 1 and 2). For this reason, the first surface 23a and the second surface 23b are also referred to as the vertically upper surface and the vertically lower surface, respectively.

[0033] With the coverlay 23 laminated on a portion of the base film 21 and a portion of the conductor circuit 22, the first surface 23a of the coverlay 23 is adhered to a portion of the second surface 21b of the base film 21 and a portion of the second surface 22b of the conductor circuit 22.

[0034] Coverlay 23 has opening 24a at the location where electronic component 10 is mounted on FPC 20. In opening 24a, bonding region 30 (pads 31, 32) of conductive circuit 22 to which electrodes 12a, 12b of electronic component 10 are bonded is exposed to the outside. In opening 24a, pad 31 forms the end of conductive circuit 22 on the -X side, and pad 32 forms the end of conductive circuit 22 on the +X side. Opening 24a is also referred to as a first opening. Bonding region 30 is also referred to as a first bonding region.

[0035] In this embodiment, opening 24a is formed in a rectangular shape, with the long sides and short sides of opening 24a extending along the length and width directions of flexible substrate 1, respectively, but this is not limited to this. Opening 24a may be formed in a shape other than rectangular depending on the shape of bonding region 30 of conductor circuit 22. Furthermore, even when opening 24a is formed in a rectangular shape, the long sides may extend in a direction other than the length direction of flexible substrate 1 and the short sides may extend in a direction other than the width direction of flexible substrate 1 depending on the arrangement of bonding region 30 of conductor circuit 22.

[0036] The opening 24a is surrounded by a metal plate 40 provided on the second surface 23b of the coverlay 23. The metal plate 40 has a first portion 41, a second portion 42, a third portion 43, and a fourth portion 44. The first portion 41 protrudes from the second surface 23b of the coverlay 23 on the −X side of the opening 24a and along the width direction of the flexible substrate 1. The second portion 42 protrudes from the second surface 23b of the coverlay 23 on the +X side of the opening 24a and along the width direction of the flexible substrate 1.

[0037] The third portion 43 protrudes from the second surface 23b of the coverlay 23 on the +Y side of the opening 24a and along the longitudinal direction of the flexible substrate 1. The fourth portion 44 protrudes from the second surface 23b of the coverlay 23 on the -Y side of the opening 24a and along the longitudinal direction of the flexible substrate 1. The -X side end and the +X side end of the third portion 43 are connected to the +Y side end of the first portion 41 and the +Y side end of the second portion 42, respectively. The -X side end and the +X side end of the fourth portion 44 are connected to the -Y side end of the first portion 41 and the -Y side end of the second portion 42, respectively.

[0038] With this configuration, the metal plate 40 surrounds the electronic component 10. In this embodiment, the provision of the metal plate 40 can improve the rigidity of the FPC 20, so no reinforcing plate is provided on the first surface 21a of the base film 21.

[0039] [Electronic component mounting] Next, a method for mounting electronic component 10 on FPC 20 will be described. As an example, a method for mounting electronic component 10 on FPC 20 using solder as a bonding material will be described.

[0040] First, with the second surface 23b of the coverlay 23 facing upward (toward the +Z side) of the flexible substrate 1, solder paste is printed on the pads 31 and 32 exposed to the outside at the opening 24a of the coverlay 23. After printing of the solder paste is completed, the electrodes 12a and 12b of the electronic component 10 are placed on the pads 31 and 32, respectively.

[0041] Next, flexible substrate 1 is placed in a reflow furnace. When flexible substrate 1 is placed in the reflow furnace, pads 31 and 32 are heated and soldered in the reflow furnace. As a result, electrodes 12a and 12b are bonded to pads 31 and 32, respectively, and electronic component 10 is mounted on FPC 20.

[0042] When manufacturing a product, the flexible substrate 1 is mounted on the product with the FPC 20 turned over and the second surface 23b of the coverlay 23 facing downward (toward the -Z side) of the flexible substrate 1. Note that the region of the FPC 20 including the portion where the electronic component 10 is mounted may be folded back so that the second surface 23b of the coverlay 23 faces downward (toward the -Z side) of the flexible substrate 1.

[0043] Electrodes 12a and 12b of electronic component 10, the bonding material, and bonding region 30 of conductor circuit 22 constitute a bonding portion 33 between electronic component 10 and conductor circuit 22. Specifically, electrode 12a of electronic component 10, fillet 13a, and pad 31 of conductor circuit 22 constitute a bonding portion 33a between electronic component 10 and conductor circuit 22. Similarly, electrode 12b of electronic component 10, fillet 13b, and pad 32 of conductor circuit 22 constitute a bonding portion 33b between electronic component 10 and conductor circuit 22.

[0044] [Actions and Effects] According to this embodiment, flexible substrate 1 includes electronic component 10, base film 21, conductor circuit 22, and coverlay 23. Electronic component 10 has electrodes 12a and 12b. Conductive circuit 22 is formed on second surface (vertically lower surface) 21b of base film 21 and has bonding region 30 where electrodes 12a and 12b are bonded using a bonding material. Coverlay 23 covers at least a portion of second surface (vertically lower surface) 22b of conductor circuit 22 and has opening 24a that exposes bonding region 30 to the outside.

[0045] In this embodiment, due to the above-described configuration, the electrodes 12a and 12b of the electronic component 10, the bonding material, and the bonding region 30 of the conductor circuit 22, which are included in the bonding portion 33 between the electronic component 10 and the conductor circuit 22, are arranged on the second surface 21b of the base film 21. Here, the second surface 21b of the base film 21 faces downward in the vertical direction.

[0046] Therefore, even if condensation occurs at opening 24a of FPC 20, the condensed water is drained vertically downward (toward the ground). This makes it possible, with a simple configuration, to prevent condensed water from accumulating at joint 33 and reliably avoid short-circuiting of electronic component 10. Therefore, in flexible substrate 1, it is possible to improve the moisture resistance of joint 33 between electronic component 10 and conductor circuit 22 while suppressing a decrease in manufacturing yield.

[0047] According to this embodiment, the flexible substrate 1 further includes a metal plate 40. The coverlay 23 further covers a portion of the second surface (vertically lower surface) 21b of the base film 21, excluding the area exposed to the outside at the opening 24a. The metal plate 40 is provided on the second surface (vertically lower surface) 23b of the coverlay 23, and surrounds the electronic component 10. No reinforcing plate is provided on the first surface (vertically upper surface) 21a of the base film 21.

[0048] Generally, when electronic components are mounted on an FPC, the FPC has excellent flexibility, so if external forces such as vibration or contact act on the FPC, the FPC will bend, applying mechanical stress to the electronic components and the joints between the electronic components and the conductor circuit, which can lead to breaks in the wiring or poor connections on the flexible substrate.

[0049] To address these issues, when mounting electronic components on an FPC, a reinforcing plate is attached to the side of the FPC opposite the side on which the electronic components are mounted. This increases the rigidity of the area where the electronic components are mounted on the FPC. As a result, even if external forces such as vibration or contact act on the FPC, the FPC is less likely to bend, reducing the mechanical stress on the electronic components and the joints between the electronic components and the conductor circuits.

[0050] However, because stiffeners are large, they must be large enough to be attached to the FPC. This makes assembly difficult when there are only a few electronic components. Furthermore, when electronic components are mounted on the FPC at a distance from each other, the number of stiffeners that must be attached to the FPC increases, increasing manufacturing costs.

[0051] In contrast, in this embodiment, with the above-described configuration, metal plate 40 is provided on the second surface of coverlay 23 and surrounds electronic component 10, thereby improving the rigidity of the portion where electronic component 10 is mounted on FPC 20. This reduces the mechanical stress applied to electronic component 10 and to joints 33 between electronic component 10 and conductor circuit 22.

[0052] Furthermore, the metal plate 40 can improve the rigidity of the portion where the electronic component 10 is mounted on the FPC 20, eliminating the need to attach a separate reinforcing plate to the FPC 20. The metal plate 40 can be processed to be flexible, so it can be made smaller than the reinforcing plate. Therefore, providing the metal plate 40 improves workability and prevents increases in manufacturing costs.

[0053] [First Modification] In the first embodiment described above, the joints 33 between the electronic components 10 and the conductor circuits 22 are directly exposed to the outside at the openings 24a of the coverlay 23. However, this is not limiting. For example, the openings 24a of the coverlay 23 may be subjected to a surface treatment.

[0054] Fig. 3 is an end view of flexible substrate 1 according to this modification. As shown in Fig. 3, opening 24a of coverlay 23 is surface-treated, and opening 24a is covered with insulating oil 50. As a result, in opening 24a, joint 33 between electronic component 10 and conductor circuit 22 is covered with insulating oil 50 and is not directly exposed to the outside.

[0055] In this modification, the above-described configuration can improve the insulating properties of the joint 33 and can further improve the moisture resistance of the joint 33.

[0056] [Second Modification] In the first embodiment described above, only the electronic component 10 is joined to the conductive circuit 22, but this is not limiting. For example, in addition to the electronic component 10, the metal plate 40 may also be joined to the conductive circuit 22.

[0057] Fig. 4 is a diagram illustrating the state of flexible substrate 1 according to this modification before electronic component 10 is mounted on FPC 20. Fig. 5 is a diagram illustrating the state of flexible substrate 1 according to this modification after electronic component 10 is mounted on FPC 20.

[0058] In this modification, in FPC 20, conductive circuit 22A is formed on base film 21 instead of conductive circuit 22 (see FIG. 4). Conductive circuit 22A has first circuit portion 25a and second circuit portion 25b. First circuit portion 25a terminates in opening 24a at pad 31, which forms the end of conductive circuit 22A on the -X side.

[0059] Second circuit portion 25b branches into three, and the first branch terminates at pad 32, which forms the +X side end of conductive circuit 22A, in opening 24a. The second branch terminates at pad 61, which will be described later, in opening 24b, which will be described later, which forms the +Y side end of conductive circuit 22A. The third branch terminates at pad 62, which will be described later, in opening 24c, which will be described later, which forms the -Y side end of conductive circuit 22A.

[0060] Conductive circuit 22A has bonding region 60 in addition to bonding region 30. Pads 31 and 32 constitute bonding region 30. Electrodes 12a and 12b of electronic component 10 are bonded to pads 31 and 32, respectively. Pads 61 and 62 constitute bonding region 60. A third portion 43 and a fourth portion 44 of metal plate 40 are bonded to pads 61 and 62, respectively (see FIG. 5 ).

[0061] The coverlay 23 has openings 24b and 24c in areas where the third portion 43 and fourth portion 44 of the metal plate 40 are provided. In the openings 24b and 24c, bonding areas 60 (pads 61 and 62) of the conductor circuit 22A to which the third portion 43 and fourth portion 44 of the metal plate 40 are bonded are exposed to the outside. The openings 24b and 24c are also referred to as second openings. The bonding area 60 is also referred to as the second bonding area.

[0062] In this modification, openings 24b, 24c are each formed in a rectangular shape, with their long sides and short sides extending along the length and width directions of flexible substrate 1, respectively, but this is not limiting. Depending on the shape of bonding region 60 of conductor circuit 22A, openings 24b, 24c may each be formed in a shape other than rectangular. Furthermore, even when openings 24b, 24c are each formed in a rectangular shape, their long sides may extend in a direction other than the length direction of flexible substrate 1 and their short sides may extend in a direction other than the width direction of flexible substrate 1, depending on the arrangement of bonding region 60 of conductor circuit 22A.

[0063] The method for joining the third portion 43 and the fourth portion 44 of the metal plate 40 to the pads 61 and 62, respectively, is the same as the method for joining the electrodes 12a and 12b of the electronic component 10 to the pads 31 and 32, respectively, and therefore will not be described here.

[0064] According to this modification, conductive circuit 22A has bonding region 60 to which parts (third portion 43 and fourth portion 44) of metal plate 40 are bonded. Coverlay 23 has openings 24b and 24c that expose bonding region 60 to the outside.

[0065] In this modified example, with the above-described configuration, for example, when it is necessary to electrically connect the flexible substrate 1 to a portion of the measurement target, the portion of the measurement target can be electrically connected to the conductor circuit 22A of the flexible substrate 1 by joining the metal plate 40 to the portion of the measurement target. Therefore, when electrically connecting the flexible substrate 1 to the portion of the measurement target, there is no need to provide a separate member, which further improves workability and further suppresses increases in manufacturing costs.

[0066] [Second embodiment] [Flexible PCB configuration] The configuration of the flexible substrate 1A according to this embodiment will be described below. Fig. 6 is a cross-sectional view of the flexible substrate 1A. In Fig. 6, only a portion of the flexible substrate 1A is shown in order to clearly show the mounting location of the connector 110.

[0067] The X direction shown in Fig. 6 corresponds to the longitudinal direction of the flexible substrate 1A. The Y direction shown in Fig. 6 corresponds to the width direction of the flexible substrate 1A and is perpendicular to the X direction. The Z direction shown in Fig. 6 corresponds to the height direction of the flexible substrate 1A and is perpendicular to the X and Y directions. In this embodiment, the Z direction corresponds to the vertical direction.

[0068] It is also possible to make the X direction and Y direction correspond to the width direction and length direction of the flexible substrate 1A, respectively.

[0069] The +X side and -X side shown in Fig. 6 correspond to the front and rear of the flexible substrate 1A, respectively. The +Y side and -Y side shown in Fig. 6 correspond to the left and right sides of the flexible substrate 1A when facing the front of the flexible substrate 1A, respectively. The +Z side and -Z side shown in Fig. 6 correspond to the top and bottom sides of the flexible substrate 1A, respectively.

[0070] 6, the flexible substrate 1A includes a connector 110, an FPC 120, a connecting portion 130, and a reinforcing plate 140. The flexible substrate 1A includes the connector 110 as an electronic component mounted on the FPC 120.

[0071] The connector 110 is provided on the flexible substrate 1A at an end of the FPC 120. The connector 110 is fitted with a mating connector (not shown) at the end of the FPC 120, and electrically connects the mating connector to the FPC 120.

[0072] The connector 110 has a plurality of terminals 111. Note that only one terminal 111 is shown in Fig. 6. One ends of the plurality of terminals 111 are accommodated in the connector 110, and when the connector 110 is mated with a mating connector, they come into contact with the plurality of terminals of the mating connector. The other ends of the plurality of terminals 111 are joined to the FPC 120 using a joining material.

[0073] The FPC 120 has the same configuration as the FPC 20 in the first embodiment. The FPC 120 has a first surface 120a and a second surface 120b that extend along the longitudinal direction of the flexible substrate 1A. The first surface 120a and the second surface 120b face in opposite directions.

[0074] When the flexible substrate 1A is mounted on a product, the first surface 120a and the second surface 120b face upward (+Z side) and downward (-Z side) of the flexible substrate 1A, respectively (see FIGS. 1 and 2). For this reason, the first surface 120a and the second surface 120b are also referred to as the vertically upper surface and the vertically lower surface, respectively.

[0075] The first surface 120a of the FPC 120 corresponds to one surface of the base film of the FPC 120. The second surface 120b of the FPC 120 corresponds to one surface of the coverlay of the FPC 120.

[0076] The connector 110 is mounted on the second surface 120b of the FPC 120. An opening is formed in the second surface 120b of the FPC 120, and the bonding area of ​​the conductive circuit of the FPC 120 is exposed to the outside through the opening. The other ends of the multiple terminals 111 of the connector 110 are bonded to the bonding area of ​​the conductive circuit of the FPC 120 through the opening in the second surface 120b. Note that the bonding area of ​​the conductive circuit is formed by pads of the conductive circuit, as in the first embodiment.

[0077] The method for joining the other ends of the multiple terminals 111 of the connector 110 to the pads of the conductive circuit of the FPC 120 is the same as the method for joining the electrodes 12a and 12b of the electronic component 10 in the first embodiment to the pads 31 and 32, respectively, and therefore will not be explained further.

[0078] The connection portion 130 is made of a bonding material piled on the other end of the plurality of terminals 111 of the connector 110. The plurality of terminals 111 of the connector 110 are electrically connected to the bonding area of ​​the conductor circuit of the FPC 120 by the connection portion 130.

[0079] The other ends of the multiple terminals 111 of the connector 110, the connection portion 130 (bonding material), and the bonding region of the conductive circuit of the FPC 120 form a bonding portion between the connector 110 and the conductive circuit of the FPC 120.

[0080] The reinforcing plate 140 is attached to the first surface 120a of the FPC 120. When viewed from a plane (XY plane) perpendicular to the height direction of the flexible substrate 1, the area where the reinforcing plate 140 is provided includes the area where the connector 110 is provided. This allows the reinforcing plate 140 to improve the rigidity of the portion of the FPC 120 where the connector 110 is mounted.

[0081] In this embodiment, the connector 110 is provided at an end of the FPC 120 and is mated with a mating connector (not shown). Therefore, the connector 110 cannot be surrounded by a metal plate, and therefore a reinforcing plate 140 is used to improve the rigidity of the portion where the connector 110 is mounted on the FPC 120.

[0082] [Actions and Effects] According to this embodiment, the flexible substrate 1A includes a connector 110 and an FPC 120. The connector 110 has a plurality of terminals 111. The FPC 120 has a bonding area where the plurality of terminals 111 are bonded using a bonding material. A second surface 120b (a surface on the lower side in the vertical direction) of the FPC 120 has an opening that exposes the bonding area to the outside.

[0083] In this embodiment, due to the above-described configuration, the other ends of the multiple terminals 111 of the connector 110, the connection portion 130 (bonding material), and the bonding region of the conductive circuit of the FPC 120, which are included in the bonding portion between the connector 110 and the conductive circuit of the FPC 120, are arranged on the second surface 120b side of the FPC 120. Here, the second surface 120b of the FPC 120 faces downward in the vertical direction.

[0084] Therefore, even if condensation occurs at the opening of the second surface 120b of the FPC 120, the condensed water is drained vertically downward (toward the ground). This makes it possible, with a simple configuration, to prevent condensed water from accumulating at the joint between the connector 110 and the conductive circuit of the FPC 120, thereby reliably avoiding the occurrence of short circuits between the terminals 111 of the connector 110. This makes it possible to improve the moisture resistance of the joint between the connector 110 and the conductive circuit of the FPC 120 while suppressing a decrease in manufacturing yield. It also makes it possible to prevent foreign matter from adhering to the second surface 120b of the FPC 120.

[0085] [Variations] In the second embodiment described above, when the flexible substrate 1A is mounted on a product, the first surface 120a and the second surface 120b of the FPC 120 face vertically upward and downward, respectively, but this is not limiting. For example, the flexible substrate 1A may be raised so that the connector 110 is located at the top end, and the first surface 120a and the second surface 120b may each face in a direction perpendicular to the vertical direction.

[0086] 7 is a cross-sectional view of flexible substrate 1A according to this modification. In this modification, flexible substrate 1A is raised so that connector 110 is located at the top end, and therefore the X direction corresponds to the vertical direction.

[0087] As shown in FIG. 7, when the flexible substrate 1A is mounted on a product, the first surface 120a and the second surface 120b of the FPC 120 each face in a direction perpendicular to the vertical direction.

[0088] With this configuration, even if condensation occurs at the opening of the second surface 120b of the FPC 120, the condensed water is drained downward in the vertical direction (toward the +X side, the ground side). This makes it possible, with a simple configuration, to prevent condensed water from accumulating at the joint between the connector 110 and the conductive circuit of the FPC 120, and to reliably avoid the occurrence of a short circuit between the terminals 111 of the connector 110. It is also possible to prevent foreign matter from adhering to the second surface 120b of the FPC 120.

[0089] [Third embodiment] [Overall configuration of busbar module] First, the configuration of a bus bar module 201 including a flexible substrate 1B according to this embodiment will be described. Fig. 8 is a plan view of the bus bar module 201. Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 8. Note that hatching is omitted in Fig. 9.

[0090] The X direction shown in Figures 8 and 9 corresponds to the longitudinal direction of flexible substrate 1B. The Y direction shown in Figures 8 and 9 corresponds to the width direction of flexible substrate 1B and is perpendicular to the X direction. The Z direction shown in Figures 8 and 9 corresponds to the height direction of flexible substrate 1B and is perpendicular to the X and Y directions. In this embodiment, the Z direction corresponds to the vertical direction.

[0091] The +X side and -X side shown in Figures 8 and 9 correspond to the front and rear of flexible substrate 1B, respectively. The +Y side and -Y side shown in Figures 8 and 9 correspond to the left and right sides of flexible substrate 1B when facing the front of flexible substrate 1B, respectively. The +Z side and -Z side shown in Figures 8 and 9 correspond to the top and bottom of flexible substrate 1B, respectively.

[0092] 8, the bus bar module 201 is included in a battery module 200 and is assembled on top of a plurality of cells 210. The battery module 200 is mounted as a power source in a vehicle such as an electric vehicle. Examples of electric vehicles include battery electric vehicles, hybrid electric vehicles, and plug-in hybrid electric vehicles.

[0093] The battery module 200 includes a bus bar module 201, a plurality of electric cells 210, and a smoke exhaust duct 250. For convenience, the following description will be given in the order of the plurality of electric cells 210, the smoke exhaust duct 250, and the bus bar module 201.

[0094] In the battery module 200, the plurality of cells 210 are arranged along the longitudinal direction of the flexible substrate 1B. In this manner, the longitudinal direction of the flexible substrate 1B corresponds to the arrangement direction of the cells 210. Although ten cells 210 are shown in FIG. 8, the number of cells 210 is not limited to ten and may be two to nine, or eleven or more.

[0095] Each of the cells 210 is, for example, a lithium ion battery. Electrode terminals 211, 212 are protruding from the upper surface of each of the two ends of the cell 210. One of the electrode terminals 211, 212 is a positive electrode, and the other of the electrode terminals 211, 212 is a negative electrode.

[0096] In a state where the plurality of unit cells 210 are arranged, the plurality of electrode terminals 211 are arranged on the +Y side to form a first electrode terminal group. In the first electrode terminal group, the electrode terminals 211 that are positive electrodes and the electrode terminals 211 that are negative electrodes are arranged alternately. In this manner, one of the two electrode terminals 211 of adjacent unit cells 210 is a positive electrode and the other is a negative electrode.

[0097] Similarly, in a state where the plurality of unit cells 210 are arranged, the plurality of electrode terminals 212 are arranged on the -Y side to form a second electrode terminal group. In the second electrode terminal group, the electrode terminals 212 that are positive electrodes and the electrode terminals 212 that are negative electrodes are arranged alternately. In this way, one of the two electrode terminals 212 of adjacent unit cells 210 is a positive electrode and the other is a negative electrode.

[0098] The smoke exhaust duct 250 is a pipe for discharging gas that is released to the outside when the gas pressure inside each cell 210 exceeds a predetermined value to the outside of the battery module 200. The smoke exhaust duct 250 extends along the arrangement direction of the cells 210, and is placed on the upper surface of each cell 210, between the electrode terminals 211, 212.

[0099] Bus bar module 201 includes flexible substrate 1B, case 220, and multiple bus bars 230a to 230c. For convenience, the following description will be given in the order of multiple bus bars 230a to 230c, flexible substrate 1B, and case 220.

[0100] Each of the multiple bus bars 230a to 230c is made of a conductive metal material and is formed in a plate shape. The multiple bus bars 230a and 230b are arranged on the +Y side of the smoke exhaust duct 250. The multiple bus bars 230c are arranged on the -Y side of the smoke exhaust duct 250. In this embodiment, the number of bus bars 230a is four, the number of bus bars 230b is two, and the number of bus bars 230c is five, depending on the number of unit cells 210 (10).

[0101] Each bus bar 230a is joined to an adjacent electrode terminal 211 in the first electrode terminal group by welding or the like. In the first electrode terminal group, the adjacent electrode terminals 211 do not include the two electrode terminals 211 arranged at both ends. As a result, the adjacent electrode terminals 211 are electrically connected to each other via the bus bar 230a.

[0102] Each bus bar 230b is joined by welding or the like to an electrode terminal 211 disposed at each end of the first electrode terminal group.

[0103] Each bus bar 230c is joined to an adjacent electrode terminal 212 in the second electrode terminal group by welding or the like, so that adjacent electrode terminals 212 are electrically connected to each other via bus bar 230c.

[0104] With this configuration, in the battery module 200, the plurality of cells 210 are electrically connected in series to form a battery pack.

[0105] The flexible substrate 1B includes an FPC 240. The FPC 240 has a trunk portion 241 and a plurality of branch portions 242a and 242b. The trunk portion 241 is formed in a substantially U-shape and has a first extending portion 241a, a second extending portion 241b, and a connecting portion 241c.

[0106] First extension portion 241a is disposed on the +Y side of smoke exhaust duct 250 and extends along the longitudinal direction of flexible substrate 1B. Second extension portion 241b is disposed on the -Y side of smoke exhaust duct 250 and extends along the longitudinal direction of flexible substrate 1B. In this way, second extension portion 241b extends parallel to first extension portion 241a.

[0107] The connecting portion 241c connects the +X side end of the first extending portion 241a and the +X side end of the second extending portion 241b at the -X side end of the connecting portion 241c. A connector 410 is mounted on the +X side end of the connecting portion 241c.

[0108] Each of the multiple branch portions 242a branches from the first extending portion 241a of the trunk 241 in a direction approaching the second extending portion 241b, and then folds back in a direction away from the second extending portion 241b so as to intersect with the first extending portion 241a in a plan view (XY plane view). Specifically, each of the multiple branch portions 242a branches from a side portion on the -Y side of the first extending portion 241a of the trunk 241, and is folded back so as to intersect with the first extending portion 241a in a plan view (XY plane view) (see FIG. 9).

[0109] Similarly, each of the multiple branch portions 242b branches off from the second extending portion 241b of the trunk 241 in a direction approaching the first extending portion 241a, and then folds back in a direction away from the first extending portion 241a so as to intersect with the second extending portion 241b in a plan view (XY plan view). Specifically, each of the multiple branch portions 242b branches off from a side portion on the +Y side of the second extending portion 241b of the trunk 241, and is folded back so as to intersect with the second extending portion 241b in a plan view (XY plan view) (see FIG. 9).

[0110] As will be described later, an electronic component 10 and a metal plate 340 are mounted on end 300 (+Y side) of each folded branch portion 242a. End 300 of each folded branch portion 242a is electrically connected via metal plate 340 to bus bar 230a or bus bar 230b, which is arranged on the +Y side of smoke exhaust duct 250.

[0111] Similarly, as will be described later, electronic components 10 and metal plates 340 are mounted on end portions 300 (-Y side) of each folded-back branch portion 242b. End portions 300 of each folded-back branch portion 242b are electrically connected via metal plates 340 to bus bars 230c that are arranged on the -Y side of smoke exhaust duct 250.

[0112] As shown in Fig. 8, the case 220 is assembled to the top of the plurality of cells 210. As shown in Fig. 9, the case 220 has a plurality of terminal insertion holes 221a, busbar support portions 222a, trunk accommodating portions 223a, and branch support portions 224a on the +Y side of the smoke exhaust duct 250. Note that Fig. 9 shows only one terminal insertion hole 221a.

[0113] A plurality of electrode terminals 211 are inserted into the plurality of terminal insertion holes 221a, respectively. The busbar support portion 222a, the stem accommodating portion 223a, and the branch support portion 224a each extend along the arrangement direction of the cells 210. The busbar support portion 222a supports a plurality of busbars 230a, 230b. The stem accommodating portion 223a accommodates a first extension portion 241a of the stem 241 of the FPC 240. The branch support portion 224a supports the branch 242a of the FPC 240.

[0114] Similarly, case 220 has a plurality of terminal insertion holes 221b, busbar support portions 222b, trunk accommodating portions 223b, and branch support portions 224b on the -Y side of smoke exhaust duct 250. Note that only one terminal insertion hole 221b is shown in FIG.

[0115] A plurality of electrode terminals 212 are inserted into the plurality of terminal insertion holes 221b, respectively. The busbar support portion 222b, the stem accommodating portion 223b, and the branch support portion 224b each extend along the arrangement direction of the cells 210. The busbar support portion 222b supports a plurality of busbars 230c. The stem accommodating portion 223b accommodates the second extending portion 241b of the stem 241 of the FPC 240. The branch support portion 224b supports the branch portion 242b of the FPC 240.

[0116] In this embodiment, the length of each folded branch portion 242a is greater than the width of the first extending portion 241a of the trunk portion 241 (see FIG. 9), but is not limited to this. The length of each folded branch portion 242a may be less than the width of the first extending portion 241a of the trunk portion 241. In this case, the branch support portion 224a is disposed at a position where it can support each folded branch portion 242a.

[0117] Similarly, the length of each folded branch portion 242b is greater than the width of the second extending portion 241b of the trunk portion 241 (see FIG. 9), but is not limited to this. The length of each folded branch portion 242b may be smaller than the width of the second extending portion 241b of the trunk portion 241. In this case, the branch support portion 224b is disposed at a position where it can support each folded branch portion 242b.

[0118] [Flexible PCB configuration] Next, the configuration of the flexible substrate 1B will be described. Fig. 10 is a diagram illustrating the flexible substrate 1B before the multiple branch portions 242a and 242b branching from the trunk portion 241 of the FPC 240 are folded back. Fig. 11 is a diagram illustrating the flexible substrate 1B after the multiple branch portions 242a and 242b branching from the trunk portion 241 of the FPC 240 are folded back. Fig. 12 is a diagram illustrating the flexible substrate 1B before an electronic component 10 is mounted on an end portion 300 of the branch portion 242a or 242b of the FPC 240. Fig. 13 is a diagram illustrating the flexible substrate 1B after an electronic component 10 is mounted on an end portion 300 of the branch portion 242a or 242b of the FPC 240.

[0119] Flexible substrate 1B includes a plurality of electronic components 10, FPC 240, a plurality of metal plates 340, and connector 410. As described above, the plurality of electronic components 10 and the plurality of metal plates 340 are mounted on ends 300 of a plurality of branch portions 242a, 242b of FPC 240. The configuration of end portion 300 of each branch portion will be described later.

[0120] As described above, the FPC 240 has the trunk 241 and the multiple branch portions 242a, 242b. The trunk 241 has a first extending portion 241a, a second extending portion 241b, and a connecting portion 241c.

[0121] In this embodiment, the FPC 240 includes a base film 21, a plurality of conductive circuits 22B, and a coverlay 23. The base film 21 is the substrate of the FPC 240, and defines the overall shape of the FPC 240.

[0122] The plurality of conductive circuits 22B are formed on the second surface 21b of the base film 21. Each of the plurality of conductive circuits 22B has one end electrically connected via electronic component 10 to a metal plate 340 mounted on the end 300 of each branch, and the other end electrically connected to a connector 410 mounted on the trunk 241. As described above, each metal plate 340 is electrically connected to a corresponding bus bar.

[0123] In this embodiment, each conductive circuit 22B functions as a voltage detection line. Connector 410 is connected to, for example, an ECU (Electric Control Unit) (not shown). The ECU can detect the voltage of each cell 210 by acquiring the voltage from multiple conductive circuits 22B.

[0124] Coverlay 23 covers second surface 21b of base film 21 and second surface 22b of conductor circuit 22, except for one area of ​​second surface 21b of base film 21 and one area of ​​second surface 22b of conductor circuit 22 (bonding areas 30, 60) that are exposed to the outside at openings 24a to 24c at end 300 of each branch (see FIG. 12 ). In this way, coverlay 23 is laminated on part of base film 21 and part of conductor circuit 22 on the side of second surface 21b of base film 21 and the side of second surface 22b of conductor circuit 22.

[0125] Next, the folding back of the multiple branch portions 242a, 242b in the FPC 240 will be described.

[0126] 10, before the branch portions 242a are folded back, each of the branch portions 242a branches off from the first extending portion 241a of the trunk portion 241 and extends in a direction approaching the second extending portion 241b. Specifically, each of the branch portions 242a branches off from the -Y side of the first extending portion 241a of the trunk portion 241 and extends to the -Y side along the width direction of the flexible substrate 1B. In this state, an electronic component 10 and a metal plate 340 are mounted on the end portion 300 of each branch portion 242a.

[0127] Similarly, before the multiple branch portions 242b are folded back, each of the multiple branch portions 242b branches off from the second extending portion 241b of the trunk portion 241 and extends in a direction approaching the first extending portion 241a. Specifically, each of the multiple branch portions 242b branches off from the +Y side of the second extending portion 241b of the trunk portion 241 and extends to the +Y side along the width direction of the flexible substrate 1B. In this state, an electronic component 10 and a metal plate 340 are mounted on the end portion 300 of each branch portion 242b.

[0128] As shown in FIG. 11, when an electronic component 10 and a metal plate 340 are mounted on the end 300 of each branch portion 242a, each of the multiple branch portions 242a is folded back in a direction away from the second extension portion 241b so as to intersect with the first extension portion 241a in a planar view (XY planar view).

[0129] Similarly, when an electronic component 10 and a metal plate 340 are mounted on the end 300 of each branch portion 242b, each of the multiple branch portions 242b is folded back in a direction away from the first extension portion 241a so as to intersect with the second extension portion 241b in a planar view (XY planar view).

[0130] After the plurality of branch portions 242a, 242b are folded back, FPC 240 is assembled into case 220 and electrically connected to the plurality of bus bars 230a to 230c via the plurality of metal plates 340 (see FIG. 9).

[0131] Next, we will explain the configuration of the ends 300 of the multiple branch portions 242a, 242b in the FPC 240. The configuration of the ends 300 of each branch portion in the FPC 240 is the same as the configuration of the FPC 20 according to the second modified example of the first embodiment (see FIG. 4), except for the conductive circuit 22B and the metal plate 340. Note that the longitudinal direction (Y direction) and width direction (X direction) of each branch portion in the FPC 240 correspond to the width direction (Y direction) and longitudinal direction (X direction) of the FPC 20 according to the second modified example of the first embodiment, respectively.

[0132] 12, in the present embodiment, in place of conductive circuit 22 in FPC 20, conductive circuit 22B is formed on base film 21. Conductive circuit 22B has first circuit portion 25a1, auxiliary circuit portion 25a2, and second circuit portion 25b.

[0133] The configuration of the first circuit portion 25a1 is the same as that of the first circuit portion 25a according to the second variant of the first embodiment, except that it is electrically connected to an auxiliary circuit portion 25a2 formed on the first surface 21a of the base film 21 via a via hole 25a3.

[0134] An insulating coverlay (not shown) that covers at least the auxiliary circuit portion 25a2 is separately provided on the first surface 21a side of the base film 21. When the auxiliary circuit portion 25a2 extends a predetermined length, it is electrically connected to a circuit portion (not shown) of the conductor circuit 22B formed on the second surface 21b of the base film 21 through a via hole (not shown).

[0135] The configuration of the second circuit section 25b is the same as the configuration of the second circuit section 25b according to the second modified example of the first embodiment, and therefore a description thereof will be omitted.

[0136] 13, opening 24a is surrounded by metal plate 340 provided on coverlay 23 at one end 341 of metal plate 340. Therefore, electronic component 10 is surrounded by metal plate 340. Metal plate 340 is bonded to bonding region 60 (pads 61, 62) of conductive circuit 22B using a bonding material.

[0137] Metal plate 340 extends a predetermined length from end 300 of each branch along the longitudinal direction of the branch. Other end 342 of metal plate 340 is joined to each bus bar by welding or the like (see FIG. 9 ). With this configuration, electronic component 10 is electrically connected to each bus bar via second circuit portion 25b of conductive circuit 22B and metal plate 340.

[0138] In this embodiment, since the rigidity of the end portion 300 of each branch portion can be improved by providing a metal plate 340, no reinforcing plate is provided on the first surface 21a of the base film 21 at the end portion 300.

[0139] [Actions and Effects] According to this embodiment, the flexible substrate 1B is included in a bus bar module 201. The bus bar module 201 has a plurality of bus bars 230a that electrically connect the positive and negative electrode terminals 211, 211 of adjacent cells 210, 210, and a plurality of bus bars 230c that electrically connect the positive and negative electrode terminals 212, 212 of adjacent cells 210, 210. A metal plate 340 is joined to one of the plurality of bus bars 230a, 230c. The electronic component 10 is electrically connected to the one bus bar via a conductor circuit 22B and the metal plate 340.

[0140] In this embodiment, the bus bar can be electrically connected to conductive circuit 22B by joining metal plate 340 to the bus bar using the above-described configuration. Therefore, there is no need to provide a separate member when electrically connecting conductive circuit 22B to the bus bar, which further improves workability and further suppresses increases in manufacturing costs.

[0141] According to this embodiment, flexible substrate 1B includes trunk 241 and multiple branch portions 242a, 242b branching from trunk 241. Each of multiple branch portions 242a, 242b is folded back so as to intersect with trunk 241 in a plan view. End portion 300 of each of multiple branch portions 242a, 242b includes electronic component 10, base film 21, conductive circuit 22B, coverlay 23, and metal plate 340.

[0142] In this embodiment, with the above-described configuration, each of the multiple branch portions 242a, 242b is folded back so as to intersect with the trunk portion 241 in a plan view, so that the length of each branch portion can be secured while reducing the amount of protrusion of each branch portion in the width direction of the flexible substrate 1B (the spread of each branch portion in the width direction of the flexible substrate 1B). Therefore, even if thermal expansion occurs in the battery module 200, the intersection can be easily absorbed by each branch portion.

[0143] According to this embodiment, the trunk portion 241 is formed in a generally U-shape and has a first extending portion 241a, a second extending portion 241b, and a connecting portion 241c. The second extending portion 241b extends parallel to the first extending portion 241a. The connecting portion 241c connects an end of the first extending portion 241a to an end of the second extending portion 241b.

[0144] When each of the plurality of branch portions 242a branches from the first extending portion 241a in a direction approaching the second extending portion 241b, it is folded back in a direction away from the second extending portion 241b so as to intersect with the first extending portion 241a in a plan view. When each of the plurality of branch portions 242b branches from the second extending portion 241b in a direction approaching the first extending portion 241a, it is folded back in a direction away from the first extending portion 241a so as to intersect with the second extending portion 241b in a plan view.

[0145] In this embodiment, with the above-described configuration, the multiple branch portions 242a branch from the first extending portion 241a in a direction approaching the second extending portion 241b. Therefore, compared to a case where the multiple branch portions 242a branch from the first extending portion 241a in a direction away from the second extending portion 241b, it is possible to reduce the area of ​​the FPC 240 that is not used as branch portions, thereby reducing waste material.

[0146] Similarly, the multiple branch portions 242b branch from the second extending portion 241b in a direction approaching the first extending portion 241a. Therefore, compared to a case where the multiple branch portions 242b branch from the second extending portion 241b in a direction away from the first extending portion 241a, it is possible to reduce the area of ​​the FPC 240 that is not used as branch portions, thereby reducing waste material.

[0147] According to this embodiment, the bus bar module 201 includes a case 220, a plurality of bus bars 230a, 230c, and an FPC 240. The case 220 is assembled to a battery module 200 having a plurality of cells 210. Each of the plurality of bus bars 230a is supported by the case 220 and electrically connects the positive and negative electrode terminals 211, 211 of adjacent cells 210, 210, among the plurality of cells 210. Each of the plurality of bus bars 230c is supported by the case 220 and electrically connects the positive and negative electrode terminals 212, 212 of adjacent cells 210, 210, among the plurality of cells 210. The FPC 240 is housed in the case 220.

[0148] The FPC 240 includes a trunk 241 and a plurality of branch portions 242a, 242b branching from the trunk 241. The plurality of branch portions 242a, 242b are folded back so as to intersect with the trunk 241 in a plan view, and are electrically connected to the plurality of bus bars 230a, 230c, respectively.

[0149] Each of the end portions 300 of the multiple branch portions 242a, 242b includes an electronic component 10, a base film 21, a conductive circuit 22B, a coverlay 23, and a metal plate 340. The electronic component 10 includes electrodes 12a, 12b. The conductive circuit 22B is formed on the second surface (vertically lower surface) 21b of the base film 21 and includes a bonding region 30 and a bonding region 60. The coverlay 23 covers at least a portion of the second surface (vertically lower surface) 21b of the conductive circuit 22B and includes openings 24a to 24c. The opening 24a exposes the bonding region 30 to the outside. The openings 24b and 24c expose the bonding region 60 to the outside. The metal plate 340 is provided on the second surface (vertically lower surface) 23b of the coverlay 23 and surrounds the electronic component 10.

[0150] In opening 24a, electrodes 12a, 12b are bonded to bonding region 30 using a bonding material. In openings 24b, 24c, one end 341 of metal plate 340 is bonded to bonding region 60. The other end 342 of metal plate 340 is bonded to each of multiple bus bars 230a, 230c. Electronic component 10 is electrically connected to each of multiple bus bars 230a, 230c via conductor circuit 22B and metal plate 340.

[0151] In this embodiment, due to the above-described configuration, electrodes 12a and 12b of electronic component 10, the bonding material, and bonding region 30 of conductor circuit 22B, which are included in bonding portion 33 between electronic component 10 and conductor circuit 22B, are arranged on second surface 21b of base film 21. Here, second surface 21b of base film 21 faces downward in the vertical direction.

[0152] Therefore, even if condensation occurs at openings 24a of each branch of FPC 240, the condensed water is drained vertically downward (toward the ground). This simple configuration makes it possible to prevent condensed water from accumulating at joints 33 and reliably avoid short circuits in electronic component 10. Therefore, in busbar module 201, it is possible to improve the moisture resistance of joints 33 between electronic component 10 and conductor circuit 22 while suppressing a decrease in manufacturing yield.

[0153] With the above-described configuration, the bus bar can be electrically connected to conductive circuit 22B by joining metal plate 340 to the bus bar. Therefore, there is no need to provide a separate member when electrically connecting conductive circuit 22B to the bus bar, which further improves workability and further suppresses increases in manufacturing costs.

[0154] With the above-described configuration, each of the multiple branch portions 242a, 242b is folded back so as to intersect with the trunk portion 241 in a plan view, so that the length of each branch portion can be secured while reducing the amount of protrusion of each branch portion in the width direction of the flexible substrate 1B (the spread of each branch portion in the width direction of the flexible substrate 1B). Therefore, even if thermal expansion occurs in the battery module 200, the intersection can be easily absorbed by each branch portion.

[0155] [Variations] In the third embodiment described above, the stem 241 of the FPC 240 is formed in a substantially U-shape because the smoke exhaust duct 250 is placed on the upper surface between the electrode terminals 211, 212 of each of the unit cells 210, but is not limited to this. For example, if the smoke exhaust duct 250 is not placed on the upper surface between the electrode terminals 211, 212 of each of the unit cells 210, the stem may be formed in a straight line.

[0156] Fig. 14 is a plan view of a flexible substrate 1B according to this modification. As shown in Fig. 14, the flexible substrate 1B includes an FPC 240A. The FPC 240A has a trunk portion 243 and multiple branch portions 244a and 244b. The trunk portion 243 is formed linearly and has an extending portion 243a and a connecting portion 243b.

[0157] The extending portion 243a extends along the longitudinal direction of the flexible substrate 1B. The connecting portion 243b is connected at its -X side end to the +X side end of the extending portion 243a, and the connector 410 is mounted at the +X side end of the connecting portion 243b.

[0158] Each of the multiple branch portions 244a branches off from one side surface (-Y side) of the extending portion 243a and then folds back toward the +Y side so as to intersect with the extending portion 243a in a plan view (XY plan view). Similarly, each of the multiple branch portions 244b branches off from the other side surface (+Y side) of the extending portion 243a and then folds back toward the -Y side so as to intersect with the extending portion 243a in a plan view (XY plan view). The multiple branch portions 244a, 244b are alternately provided along the longitudinal direction of the flexible substrate 1B.

[0159] Furthermore, if the flexible substrate 1B can be assembled above the smoke exhaust duct 250, the trunk can be formed in a straight line even if the smoke exhaust duct 250 is placed on the upper surface between the electrode terminals 211, 212 of each battery cell 210.

[0160] With this configuration, each of the multiple branch portions 244a, 244b is folded back so as to intersect with the trunk portion 243 in a plan view, so that the length of each branch portion can be secured while reducing the amount of protrusion of each branch portion in the width direction of the flexible substrate 1B (the spread of each branch portion in the width direction of the flexible substrate 1B). Therefore, even if thermal expansion occurs in the battery module 200, the intersection can be easily absorbed by each branch portion.

[0161] [Other variations] Two or more of the first embodiment, the first and second modified examples of the first embodiment, the second embodiment, the modified example of the second embodiment, the third embodiment, and the modified example of the third embodiment may be combined and applied to the flexible substrate and bus bar module.

[0162] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment. [Explanation of symbols]

[0163] 1, 1B flexible board 10. Electronic Components 12a, 12b electrode 21 Base film 21a 1st page 21b 2nd side 22, 22A, 22B Conductor circuit 22b 2nd side 23 Coverlay 23b 2nd side 24a~24c opening 30 Joint area 40, 340 Metal Plate 60 Junction area 201 Busbar Module 211, 212 Electrode terminal 230a, 230c busbars 241, 243 executives 241a 1st extension part 241b 2nd extension part 241c Connection site 242a, 242b, 244a, 244b branches 300 End

Claims

1. an electronic component having an electrode; A base film; a conductor circuit formed on a vertically lower surface of the base film and having a first bonding region to which the electrode is bonded using a bonding material; a coverlay covering at least a portion of a vertically lower surface of the conductor circuit and having a first opening exposing the first bonding region to the outside; A metal plate and A flexible substrate comprising: the coverlay further covers a portion of the lower surface of the base film in the vertical direction, excluding a region exposed to the outside through the first opening; the metal plate is provided on a vertically lower surface of the coverlay and surrounds the electronic component, No reinforcing plate is provided on the vertical upper surface of the base film, the flexible substrate includes a trunk portion and a branch portion branching from the trunk portion; The branch portion is folded back so as to intersect with the trunk portion in a plan view, The end of the branch portion is a flexible substrate having the electronic component, the base film, the conductor circuit, the coverlay, and the metal plate.

2. The flexible substrate according to claim 1 , wherein the first opening is covered with insulating oil.

3. the conductor circuit has a second bonding area to which a portion of the metal plate is bonded; The flexible substrate according to claim 1 , wherein the coverlay has a second opening that exposes the second bonding region to the outside.

4. The busbar module includes a plurality of busbars that electrically connect the positive and negative electrode terminals of adjacent cells, the metal plate is joined to one of the plurality of bus bars; The flexible substrate according to claim 3 , wherein the electronic component is electrically connected to the one bus bar via the conductor circuit and the metal plate.

5. The trunk portion is formed in a substantially U-shape and has a first extension portion, a second extension portion extending parallel to the first extension portion, and a connecting portion connecting an end of the first extension portion and an end of the second extension portion, When the branch portion branches from the first extension portion in a direction approaching the second extension portion, the branch portion is folded back in a direction away from the second extension portion so as to intersect with the first extension portion in a plan view, The flexible substrate according to claim 4, wherein when the branch portion branches from the second extension portion in a direction approaching the first extension portion, the branch portion is folded back in a direction away from the first extension portion so as to intersect with the second extension portion in a planar view.

6. a case that is assembled to a battery module having a plurality of single cells; a bus bar supported by the case and electrically connecting electrode terminals of positive and negative electrodes of adjacent cells among the plurality of cells; a flexible substrate accommodated in the case; Equipped with The flexible substrate is With executives, a branch portion branching from the trunk portion, folding back so as to intersect with the trunk portion in a plan view, and electrically connected to the bus bar; and The end of the branch portion is an electronic component having an electrode; A base film; a conductor circuit formed on a vertically lower surface of the base film, the conductor circuit having a first bonding region and a second bonding region; a coverlay covering at least a portion of a vertically lower surface of the conductor circuit, the coverlay having a first opening exposing the first bonding region to the outside and a second opening exposing the second bonding region to the outside; A metal plate and and the coverlay further covers a portion of the lower surface of the base film in the vertical direction, excluding a region exposed to the outside through the first opening; the metal plate is provided on a vertically lower surface of the coverlay and surrounds the electronic component, In the first opening, the electrode is bonded to the first bonding region using a bonding material, In the second opening, one end of the metal plate is joined to the second joining region, the other end of the metal plate is joined to the bus bar, The electronic component is electrically connected to the bus bar via the conductor circuit and the metal plate.

Images