Flexible substrate and battery connection structure

Abstract

To obtain a flexible substrate capable of stably extracting an output from an electrode to be connected even when the position of the electrode varies.SOLUTION: A flexible substrate 10 is provided with a plate-shaped substrate main body 20 perpendicular to a vertical direction and an elongated connecting part 30. The connecting part 30 includes a take-out part 31, a bent part 32, a first extending part 33 extending toward a positive side in an x direction, a folded part 34, a second extending part 35 extending in parallel with and opposite to the first extending part 33, and a fixing part 36. The first extending part 33 is inclined downward toward the positive side in the x direction. In addition, the second extending part 35 is formed to be inclined downward toward a negative side in the x direction. Even when inclination angles of the first extending part 33 and the second extending part 35 are small, the fixing part 36 can be sufficiently lower than the substrate main body 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flexible substrate structure used for battery cells and the like, and a battery connection structure using the same. [Background technology]

[0002] In battery cells used in automobiles and other applications, a large current output is extracted from each battery in an assembly of many arranged batteries, which are connected in series, for example. For this purpose, a circuit board equipped with terminals connected to the electrodes of each battery is attached to the battery cell (battery assembly). During this process, the positions of the battery terminals fluctuate due to factors such as heat generation from the battery during use, thermal expansion due to the ambient temperature, and expansion of the battery itself. Since each battery outputs a large current, the connections between the board and each battery must be secure and have low resistance.

[0003] To accommodate such positional variations, a flexible substrate (flexible printed circuit board) is used as the substrate, as described in Patent Document 1, for example. In a flexible substrate, a wiring pattern through which a current flows is formed on a substrate made of a thin, flexible resin material. A connection part on which the wiring pattern is provided extends from the substrate body and is fixed to an electrode on the battery side.

[0004] 7A is a plan view showing the state when this flexible substrate 300 is attached to the battery 50, and FIG. 7B is a cross-sectional view taken along the line AA of FIG. 7B. Here, this flexible substrate 300 is connected to an electrode (positive electrode or negative electrode) 55 of the battery 50. The flexible substrate 300 comprises a plate-shaped substrate main body 310 and a thin connecting portion 320 extending from the substrate main body 310 and connected to the electrode 55. Note that wiring patterns are formed on the substrate main body 310 and the connecting portion 320 as appropriate, but are not shown. The substrate main body 310 is configured so that this current can be extracted to the outside.

[0005] 7(a), the connection portion 320, one end of which is connected to the substrate body 310, is bent in the horizontal direction (in-plane direction of the flexible substrate 300), and a rectangular metal plate-like connection terminal 40 is connected to a fixing portion 330 provided on the other end side, and this connection terminal 40 is connected via a metal bonding layer 57 on the electrode 55. With this structure, the connection with the electrode 55 on the battery 50 side is maintained even if the position of the battery 50 (electrode 55) changes. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-97917 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0007] With the above structure, even if the position of the battery 50 (electrodes 55) changes, it is possible to stably maintain connection to the electrodes 55. However, the position of the battery 50 may change in either the left-right direction or the up-down direction in FIG. 7(a), and both directions may also occur simultaneously.

[0008] Figure 8 is a plan view corresponding to Figure 7(a) in this case. In this case, although the connection between the connection terminal 300 and the electrode 55 is stably maintained, the connection portion 300 is deformed, and the connection portion 320 and the substrate main body 310 may interfere with each other as in region B, or different portions of the bent connection portion 320 may interfere with each other as in region C. In this case, due to manufacturing tolerances, interference may be particularly likely to occur in portions that are closely spaced even before deformation, such as region C. This may damage the connection portion 320 or the substrate main body 310, causing problems with drawing current from the battery 50.

[0009] The present invention has been made in view of the above circumstances, and has as its object to solve the above problems. [Means for solving the problem]

[0010] The present invention relates to a flexible substrate, which is a thin plate-shaped substrate made of a flexible material and on which a wiring pattern is formed that serves as a path for current from a battery, and which comprises a substrate main body having a surface perpendicular to the vertical direction, and a connection portion that branches off and extends from an extraction portion in the substrate main body in a planar view, and whose tip is a fixed portion that is fixed to an electrode of the battery, and the connection portion is bent at multiple points in a planar view from the extraction portion to the fixed portion, changing the extension direction, and is formed at an angle so that the distance from the substrate main body along the vertical direction increases when it moves away from the extraction portion along the extension direction, thereby resulting in a configuration in which the fixed portion and the substrate main body are not located at the same height in the vertical direction. The connection portion may include a first extension portion and a second extension portion that extend in opposite directions along a second direction perpendicular to a first direction that is the direction from the substrate body toward the battery in a planar view. The present invention also provides a battery connection structure using the flexible substrate, wherein the fixing portion and the electrode are connected via a plate-shaped connection terminal. The substrate body may be disposed above the electrodes, and the connection terminal may be joined to the lower side of the fixed portion. [Effects of the Invention]

[0011] Since the present invention is configured as described above, it is possible to obtain a flexible substrate that can stably extract output from the electrodes even if the positions of the electrodes to be connected fluctuate. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a plan view showing a first form (electrode connection structure) when a flexible substrate according to an embodiment is used. [Figure 2] 1 is a cross-sectional view showing a first form (electrode connection structure) when a flexible substrate according to an embodiment is used. [Figure 3] 10 is a plan view showing a second form (electrode connection structure) when the flexible substrate according to the embodiment is used. FIG. [Figure 4] 10 is a cross-sectional view showing a second form (electrode connection structure) when the flexible substrate according to the embodiment is used. FIG. [Figure 5] FIG. 10 is a plan view showing a form when a first modified example of the flexible substrate according to the embodiment is used. [Figure 6] FIG. 10 is a plan view showing a configuration when a second modified example of the flexible substrate according to the embodiment is used. [Figure 7] FIG. 1 is a plan view showing a form in which a conventional flexible substrate is used. [Figure 8] FIG. 1 is a cross-sectional view showing a form in which a conventional flexible substrate is used. DETAILED DESCRIPTION OF THE INVENTION

[0013] A flexible substrate according to an embodiment of the present invention will be described. This flexible substrate is also provided with connection parts used for electrical connection with the electrodes of a battery cell (battery), and due to the flexibility of the flexible substrate, this connection is maintained even if the position of the battery (electrode) changes. Furthermore, this flexible substrate is designed so that even if the battery (electrode) moves, the connection parts connected to it and the substrate body, or different parts of the connection parts, are unlikely to interfere with each other.

[0014] 1 is a plan view showing the configuration (battery connection structure) when this flexible substrate 10 is attached to a battery 50. Here, the x, y, and z directions are defined as shown, with the y direction (first direction) being the direction connecting the substrate main body 20 and the battery 50 in a plan view, the x direction (second direction) being the direction in a horizontal plane perpendicular to the x direction, and the z direction being the vertical direction.

[0015] 7, the flexible substrate 10 is provided with a plate-shaped substrate body 20 perpendicular to the vertical direction (z direction) and a connecting portion 30 extending in an elongated shape from the substrate body 20. Also provided is a metal connecting terminal 40 for connecting the connecting portion 30 to a metal bonding layer 57 on the electrode 55. The plan view shown in FIG. 1 is substantially the same as the plan view shown in FIG. 7(a) above. Here, the connection portion 30 is composed of an extraction portion 31, which is the portion extracted from the substrate main body 20 toward the negative side in the y direction, a bent portion 32 that changes the extension direction from the extraction portion 31 by 90° (toward the x direction), a first extension portion 33 that extends from the bent portion 32 toward the positive side in the x direction, a folded portion 34 that is provided on the positive side of the first extension portion 33 in the x direction and changes the extension direction by 180°, a second extension portion 35 that extends parallel to and in the opposite direction to the first extension portion 33 due to this folding portion, and a fixing portion 36 that is provided at the tip of the second extension portion 35 and to which a connection terminal 40 is connected. The plan view shown in Figure 1 is substantially the same as the plan view shown in Figure 7(a) above.

[0016] 2A, 2B, and 2C are cross-sectional views of FIG. 1 taken along the DD (a), EE (b), and FF (c) directions, respectively. In particular, FIG. 2C corresponds to FIG. 7B. As shown in FIG. 2A, the first extension 33 is formed with a slope that slopes downward toward the positive x-direction (toward the negative z-direction). As shown in FIG. 2B, the second extension 35 is formed with a slope that slopes downward toward the negative x-direction (toward the negative z-direction). In FIG. 1, such a sloped portion is indicated by an arrow pointing downward. Therefore, as shown in FIG. 2C, the fixing portion 36 is positioned below the substrate main body 20 (negative z-direction). In this case, the distance in the z-direction between the bottom surface of the substrate main body 20 and the top surface of the connection terminal 40 is L.

[0017] In particular, by providing the bending portion 32 and the folded portion 34 in the connection portion 30, the effective length from the extraction portion 31 to the fixed portion 36 (connection terminal 40) can be made large, and even if the inclination angle of the first extension portion 33 and the second extension portion 35 in Figures 2(a) and (b) is made small, the fixed portion 36 can be made sufficiently lower than the substrate main body 20.

[0018] 1, the portion where the connecting portion 30 (first extending portion 33) and the substrate main body 20 face each other is shown as region B0, corresponding to region B in Fig. 8, and the portion where the first extending portion 33 and the fixing portion 36 face each other is shown as region C0, corresponding to region C. With the above configuration, the first extending portion 33 is located lower than the substrate main body 20 in region B0, and the fixing portion 36 is located lower than the first extending portion 33 in region C0. Therefore, even if the connecting portion 30 (flexible substrate 10) is deformed in the same way as in Fig. 8, interference between them in regions B0 and C0 is suppressed.

[0019] 1 and 2, even if there is a small movement of electrode 55 (battery 50) in the z direction, it is clear that connection part 30 can follow this by deforming. Therefore, even if the position of connected electrode 55 fluctuates, output from this electrode can be stably extracted.

[0020] 1 shows a configuration in which one flexible substrate 10 is connected to a single battery 50, but in reality, other flexible substrates are similarly connected to other batteries 50 adjacent to this battery 50. In this case, the substrate bodies of the flexible substrates may be common or separate. If separate, the height of the substrate bodies may be different for each battery, and the inclination angle in FIG. 2 may be changed accordingly.

[0021] 1 and 2, but showing a structure (electrode connection structure) in which the above-described flexible substrate 10 is used in a different manner from that shown in FIGS. 1 and 2. In the example shown in FIGS. 1 and 2, the connection terminal 40 is connected to the upper side (positive side in the z direction) of the fixed portion 35, but in this configuration, the connection terminal 40 is connected to the lower side of the fixed portion 35. Here, it is assumed that when attached, the connection terminal 40 is maintained horizontally as shown in FIG. 4(c).

[0022] If the distance in the z direction between the substrate main body 20 and the connection terminal 40 in Fig. 2(c) is L and this distance is the same in the configurations of Figs. 3 and 4 as shown in Fig. 4(c), then the height of the fixing portion 36 can be made higher by the thickness of the connection terminal 40. Therefore, the inclination angles of the first extension portion 33 and the second extension portion 35 in Figs. 4(a) and 4(b) can be made gentler than those in Figs. 2(a) and 2(b).

[0023] 2 and 4, the resin material that is the main component of flexible substrate 10 is made sufficiently thinner than connection terminals 40 and the like, and it is clear that this configuration also suppresses interference between connection portion 30 and substrate body 20, and between first extension portion 33 and fixed portion 36. On the other hand, when this configuration is used, the overall length of connection portion 30 can be shortened by the amount of the gentler slope, and the overall strength can also be increased.

[0024] In the flexible substrate 10 described above, the planar shape of the connection portion, in particular, can be modified as appropriate. In the flexible substrate 110 (first modification) shown in FIG. 5, a connection portion 130 is formed on the substrate body 120, bending as shown. While the connection portion 30 described above has two portions (bend portion 32 and folded portion 34) where the extension direction is changed, this connection portion 130 has bend portions 131, 132, 133, and 134 where the extension direction is changed by 90 degrees, and a fixed portion 135 is provided at the tip. By providing multiple bend portions in this manner and tilting the connection portion 130 toward the tip between the bend portions as shown by the arrows in FIG. 5, similar to FIGS. 2(a) and (b), output can be similarly stably extracted from the electrode 55. Furthermore, in this case, similar to the configurations in FIGS. 3 and 4, the connection terminal 40 is connected to the underside of the fixed portion 135.

[0025] In the flexible substrate 210 (second modified example) shown in FIG. 6, a connecting portion 230 having the illustrated shape is formed on the substrate body 220. This connecting portion 230 is provided with bent portions 231, 232, and 233, each of which changes its extension direction by 90°, and an arc-shaped curved portion 234 is provided between bent portions 232 and 233. In this way, a similar effect can be achieved by combining bent portions and curved portions with a curved shape and inclining each portion toward the tip (fixed portion 235 side) as shown by the arrows in FIG. 6. In this case, as in the configurations of FIGS. 3 and 4, the connecting terminal 40 is connected to the underside of the fixed portion 235.

[0026] In this way, by providing multiple bent or folded sections and tilting the connection section between them toward the tip side as in Figures 2(a) and (b), it is possible to similarly stably extract output from electrode 55.

[0027] In the above example, the fixing portion is provided below the substrate body (negative side in the z-direction), but the fixing portion may be configured to be above the substrate body depending on the positional relationship between the substrate body (flexible substrate) and the battery. In this case, the inclination of the connection portions (first extension portion 33, second extension portion 35) shown in Figures 2(a) and 2(b) may be reversed. In other words, each region of the connection portion may be configured to incline vertically relative to the substrate body toward the side where the fixing portion is provided at its tip.

[0028] The structure of the substrate body is set appropriately depending on the method of extracting current from the battery, and the connection portion is configured appropriately so that the path of the current is secured from the fixed portion.

[0029] The present invention has been described above based on an embodiment. This embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components, and that such modifications are also within the scope of the present invention. [Explanation of symbols]

[0030] 10, 110, 210, 300 Flexible board (flexible printed circuit board) 20, 120, 220, 310 PCB body 30, 130, 320 connection part 31 Removal section 32 Bend 33 1st extension section 34 Folded section 35 2nd extension section 36, 135, 235, 330 Fixed part 40 Connection terminal 50 batteries 55 electrode 57 Bonding layer 131-134, 231-233 Bends 234 Curved section

Claims

1. A flexible substrate is a thin plate-like substrate made of a flexible material and having a wiring pattern formed thereon to serve as a path for current from the battery, a substrate body having a surface perpendicular to a vertical direction; a connecting portion that branches off from the extraction portion of the substrate body in a plan view, and extends, and has a tip portion that serves as a fixing portion that is fixed to an electrode of the battery; Equipped with A flexible substrate characterized in that the connection portion is bent at multiple points in a planar view from the extraction portion to the fixed portion, changing the extension direction, and is formed at an angle so that the distance from the substrate main body in the vertical direction increases when it moves away from the extraction portion along the extension direction, thereby causing the fixed portion and the substrate main body to not be located at the same height in the vertical direction.

2. The flexible substrate according to claim 1, characterized in that the connection portion includes a first extension portion and a second extension portion that extend in opposite directions along a second direction perpendicular to a first direction that is a direction from the substrate main body toward the battery in a planar view.

3. A battery connection structure using the flexible substrate according to claim 1 or 2, The battery connection structure is characterized in that the fixing portion and the electrode are connected via a plate-shaped connection terminal.

4. the substrate body is disposed above the electrodes, The battery connection structure according to claim 3 , wherein the connection terminal is joined to a lower side of the fixing portion.

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