Wiring structure

Abstract

To provide a wiring structure that is easy to handle. [Solution] The wiring structure 100 consists of a flexible plate-shaped base material 20 and N wiring boards 10 (where N is a natural number between 3 and 200) each containing a plurality of wires arranged side by side on the base material 20, which are connected in series between the N wiring boards 10, with each of the plurality of wires electrically connected to the others.

Description

Technical Field

[0001] The present disclosure relates to a wiring structure.

Background Art

[0002] A wiring board in which a plurality of wirings are formed on a flexible base material has been conventionally proposed. For example, Patent Document 1 discloses a flexible printed board including a flexible base material and a conductor layer formed on the surface of the base material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Requirements for wiring boards are diversifying. For example, there may be a need for a wiring board that is sufficiently long compared to a wiring board used in a small electronic device such as a portable information device. However, a single wiring board formed to be sufficiently long is practically difficult to handle. For example, as a result of the excessive weight of the wiring board, it is difficult to transport the wiring board. Also, for example, assuming a situation where a long wiring board is transported or stored in a state of being wound around a core material, it is necessary to correct the remaining winding distortion of the wiring board linearly at the mounting stage. In view of the above circumstances, one aspect of the present disclosure aims to provide a wiring structure that is easy to handle.

Means for Solving the Problems

[0005] A wiring structure according to one aspect of the present disclosure includes N (N is a natural number of 3 or more and 200 or less) wiring boards each including a plate-shaped base material having flexibility and a plurality of wirings arranged in parallel on the base material, and the plurality of wirings are electrically connected to each other between the N wiring boards and are connected in series to each other. [Brief explanation of the drawing]

[0006] [Figure 1] This is a plan view of the wiring board in the first embodiment. [Figure 2] This is a cross-sectional view of line aa in Figure 1. [Figure 3] This is a cross-sectional view of line bb in Figure 1. [Figure 4] This is a diagram illustrating the procedures for handling circuit boards. [Figure 5] This is a plan view of the wiring structure in the first embodiment. [Figure 6] This is a cross-sectional view illustrating the configuration of a connector. [Figure 7] This is a plan view of the wiring structure in the second embodiment. [Figure 8] Figure 7 is a cross-sectional view of the CC line. [Figure 9] This is a plan view of the wiring board related to configuration a. [Figure 10] This is a plan view of a wiring board relating to another embodiment of configuration a. [Figure 11] This is a plan view of a wiring board relating to another embodiment of configuration a. [Figure 12] This is a plan view of the wiring board related to configuration b. [Figure 13] This is a plan view of the wiring board in a divided state. [Figure 14] Figure 12 is a cross-sectional view of the dd line. [Figure 15] This is a plan view of the wiring board related to configuration c. [Figure 16] This is a plan view showing an example of the usage state of a wiring board related to configuration c. [Figure 17] This is a plan view showing an example of the usage state of a wiring board related to configuration c. [Figure 18] This is a plan view showing an example of the usage state of a wiring board related to configuration c. [Figure 19] This is a plan view of the wiring board related to configuration d. [Figure 20] This is a plan view of the wiring board related to configuration e. [Figure 21] It is a cross-sectional view of the e-e line in FIG. 20. [Figure 22] It is a plan view of a wiring board according to configuration f. [Figure 23] It is a plan view of a wiring board according to configuration g. [Figure 24] It is a plan view of a wiring board in an extended state. [Figure 25] It is a plan view of a wiring board according to configuration h. [Figure 26] It is a plan view of a wiring board according to configuration i. [Figure 27] It is a cross-sectional view of the f-f line in FIG. 26. [Figure 28] It is a cross-sectional view of a wiring structure formed by a wiring board according to configuration i. [Figure 29] It is a perspective view of a wiring structure in a modified example. [Figure 30] It is a perspective view of a wiring structure in a modified example.

Embodiments for Carrying Out the Invention

[0007] Embodiments for implementing the present disclosure will be described with reference to the drawings. Note that in each drawing, the dimensions and scales of each element may differ from those of an actual product. Also, the embodiments described below are exemplary embodiments assumed when implementing the present disclosure. Therefore, the scope of the present disclosure is not limited to the embodiments illustrated below.

[0008] A: First Embodiment A-1: Wiring Board 10 FIG. 1 is a plan view illustrating the configuration of a wiring board 10. FIG. 2 is a cross-sectional view of the a-a line in FIG. 1. FIG. 3 is a cross-sectional view of the b-b line in FIG. 1. The wiring board 10 is a flexible printed circuit (FPC) for electrically connecting a plurality of elements.

[0009] In the following explanation, we assume three mutually orthogonal axes (X-axis, Y-axis, and Z-axis). The wiring board 10 is a flat wiring material (i.e., a flat cable) formed in a long length in the direction of the Y-axis. That is, the direction of the Y-axis corresponds to the longitudinal direction of the wiring board 10. In the following explanation, one direction along the Y-axis will be referred to as the "Y1 direction," and the direction opposite to the Y1 direction will be referred to as the "Y2 direction." The direction of the X-axis is the short-side direction (i.e., the width direction) of the wiring board 10. In the following explanation, one direction along the X-axis will be referred to as the "X1 direction," and the direction opposite to the X1 direction will be referred to as the "X2 direction." The direction of the Z-axis corresponds to the thickness direction of the wiring board 10. In the following explanation, one direction along the Z-axis will be referred to as the "Z1 direction," and the direction opposite to the Z1 direction will be referred to as the "Z2 direction." Furthermore, observing any element with a line of sight along the Z-axis will be referred to as "planar view."

[0010] As illustrated in Figures 1 to 3, the wiring board 10 comprises a base material 20 and a plurality of wirings 30. The base material 20 is a flexible plate-shaped member. That is, the base material 20 can be easily deformed (elastically or plastically) by the action of an external force. The base material 20 is formed in an elongated shape in the direction of the Y axis. The base material 20 includes a first layer 21 and a second layer 22. The first layer 21 and the second layer 22 are composed of flexible plate-shaped members (e.g., films) parallel to the XY plane.

[0011] The first layer 21 and the second layer 22 are formed from insulating materials. Examples of insulating materials used for the first layer 21 and the second layer 22 include polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyvinyl chloride (PVC), or liquid crystal polymer (LCP). However, the materials of the first layer 21 and the second layer 22 are not limited to the above examples and may be changed as desired. Furthermore, the materials of the first layer 21 and the second layer 22 may be the same or different.

[0012] As illustrated in Figure 2, the first layer 21 is a plate-like member including an inner surface S11 and an outer surface S12 located on opposite sides of each other. The inner surface S11 is the surface of the first layer 21 facing in the Z1 direction. The outer surface S12 is the surface of the first layer 21 facing in the Z2 direction. The second layer 22 is a plate-like member including an inner surface S21 and an outer surface S22 located on opposite sides of each other. The inner surface S21 is the surface of the second layer 22 facing in the Z2 direction. The outer surface S22 is the surface of the second layer 22 facing in the Z1 direction.

[0013] The first layer 21 and the second layer 22 are joined together with a gap between them. The first layer 21 and the second layer 22 are joined by a bonding material 23. The bonding material 23 is an insulating adhesive for joining the first layer 21 and the second layer 22. Specifically, various adhesives such as acrylic resin, epoxy resin, phenolic resin, silicone resin, or polyurethane resin are exemplified as materials for the bonding material 23. Note that the bonding material 23 may be omitted.

[0014] The first layer 21 and the second layer 22 are joined together such that their inner surfaces S11 and S21 face each other. Multiple wirings 30 and joining material 23 are installed between the first layer 21 and the second layer 22. In other words, multiple wirings 30 and joining material 23 are installed inside the base material 20 composed of the first layer 21 and the second layer 22. The width of the first layer 21 and the width of the second layer 22 are substantially the same. Therefore, each edge of the first layer 21 and each edge of the second layer 22 overlap each other in a plan view.

[0015] Multiple wirings 30 are linear conductors formed from a low-resistance conductive material. Examples of conductive materials used to form each wiring 30 include metallic materials such as copper or aluminum, or alloy materials containing a low-resistance metal (e.g., copper or aluminum). Multiple wirings 30 may be thin-film conductive patterns formed by patterning a conductive film, or they may be plate-shaped wiring materials that can maintain their shape individually. In Figure 1, hatching has been added to the wirings 30 for convenience. The same applies to the following drawings.

[0016] Each of the multiple wirings 30 is a conductor extending linearly in the direction of the Y-axis. The width of each wiring 30 is substantially the same throughout the entire wiring 30. The multiple wirings 30 are arranged side by side with spacing between them in the direction of the X-axis. The spacing between each wiring 30 is substantially the same throughout the entire wiring 30. However, the shape and position of each wiring 30 may be arbitrarily changed. The width of each wiring 30 and the spacing between each wiring 30 are, for example, equal dimensions. However, configurations in which the width of each wiring 30 exceeds the spacing between each wiring 30, or configurations in which the width of each wiring 30 is less than the spacing between each wiring 30, are also conceivable.

[0017] As illustrated in Figure 2, the multiple wirings 30 are interposed between the first layer 21 and the second layer 22. Specifically, one surface of each wiring 30 contacts the inner surface S11 of the first layer 21, and the other surface of each wiring 30 contacts the inner surface S21 of the second layer 22. As described above, the multiple wirings 30 are arranged side by side on the base material 20.

[0018] As illustrated in Figure 2, the bonding material 23 is filled between the first layer 21 and the second layer 22, in the spacing between each adjacent wiring 30 in the direction of the X axis. The first layer 21 and the second layer 22 are joined together by the bonding material 23 joining the inner surface S11 of the first layer 21 and the inner surface S21 of the second layer 22. It should be noted that configurations in which the bonding material 23 is interposed between the inner surface S11 of the first layer 21 and each wiring 30, or between the inner surface S21 of the second layer 22 and each wiring 30, are also conceivable.

[0019] As illustrated in Figures 1 and 3, the wiring board 10 includes terminal section Ea and terminal section Eb. Terminal sections Ea and Eb are located on opposite sides of each other in the direction of the Y axis. Specifically, terminal section Ea is the portion of the wiring board 10 that includes one end in the Y1 direction. Terminal section Eb is the portion of the wiring board 10 that includes the other end in the Y2 direction.

[0020] The first layer 21 is removed at terminals Ea and Eb. Specifically, terminal Ea is the portion of the second layer 22 that protrudes in the Y1 direction from the Y1 direction end of the first layer 21. On the other hand, terminal Eb is the portion of the second layer 22 that protrudes in the Y2 direction from the Y2 direction end of the first layer 21.

[0021] As illustrated in Figures 1 and 3, each wiring 30 extends in the Y-axis direction across terminals Ea and Eb of the wiring board 10. Specifically, each wiring 30 is continuous across the entire length of the second layer 22. The Y1 end of each wiring 30 is located at terminal Ea of the wiring board 10. That is, the Y1 end of the wiring 30 protrudes in the Y1 direction from the Y1 end of the first layer 21 in a plan view. On the other hand, the Y2 end of each wiring 30 is located at terminal Eb of the wiring board 10. That is, the Y2 end of the wiring 30 protrudes in the Y2 direction from the Y2 end of the first layer 21 in a plan view.

[0022] As illustrated in Figures 1 and 3, a connection terminal 31a is provided at the end of each wire 30 that is exposed at terminal Ea. Multiple connection terminals 31a corresponding to different wires 30 are arranged at terminal Ea along the X-axis. The connection terminal 31a is a conductive film that covers the end of the wire 30 at terminal Ea. Similarly, a connection terminal 31b is provided at the end of each wire 30 that is exposed at terminal Eb. Multiple connection terminals 31b corresponding to different wires 30 are arranged at terminal Eb along the X-axis. The connection terminal 31b is a conductive film that covers the wire 30 at terminal Eb. The connection terminals 31a and 31b are made of a metal (e.g., gold) with lower resistance than each wire 30.

[0023] Note that connection terminals 31a and 31b may be omitted. In a configuration in which connection terminal 31a is omitted, the end of each wire 30 exposed at terminal Ea corresponds to connection terminal 31a, and the end of each wire 30 exposed at terminal Eb corresponds to connection terminal 31b.

[0024] For the wiring board 10, "flexibility" refers to the property of deforming in response to a load (external force). Flexibility can be evaluated, for example, using the ratio of the amount of deflection δ [mm] to the load P [N] (δ / P) as an index (hereinafter referred to as "flexibility index F"). The more flexible the object being evaluated, the larger the flexibility index F [mm / N] will be. For example, the flexibility index F is measured assuming that the object being evaluated is a plate-shaped member with a width of 10 mm and a total length of 500 mm, installed as a cantilever beam. For example, a wiring board with a flexibility index F exceeding 2 mm / N (more preferably exceeding 20 mm / N) can be evaluated as having "flexibility".

[0025] The length L of the wiring board 10 is 10 mm or more and 6000 mm or less. The length L is the distance between the two ends of the wiring board 10 in the direction in which the multiple wires 30 extend (the direction of the Y axis). In other words, the length L of the wiring board 10 is the distance between the two ends when the wiring board 10 is held in a straight line. As described above, since the length L of the wiring board 10 is 10 mm or more, it is easy for workers handling the wiring boards 10 to hold or transport individual wiring boards 10. The work of holding or transporting the wiring boards 10 includes, for example, the work of collecting the wiring boards 10 after manufacturing on the production line, or the work of actually assembling the wiring boards 10 after manufacturing.

[0026] Compared to configurations where the length L of the wiring board 10 is less than 10 mm, there is also the advantage that the manufacturing of the wiring board 10 is easier. For example, if the wiring board 10 is excessively short, the corners of the wiring board 10 remain sharp, which could cause damage to elements (e.g., workers) that come into contact with those corners. It is also conceivable that it would be difficult to secure a sufficient joining allowance when joining the wiring boards 10 together. For example, if the manufacturing process involves adsorbing the wiring board 10 with a suction pad, the wiring board 10 may not be able to be properly adsorbed if its length is smaller than the minimum size that the suction pad can adsorb. In the first embodiment, since the length L of the wiring board 10 is 10 mm or more, the problems described above can be solved. Specifically, according to the first embodiment, the possibility of damage to elements that come into contact with the corners of the wiring board 10 is reduced, it is easy to secure a sufficient joining allowance during joining, and the wiring board can be properly adsorbed by a suction pad during the manufacturing process.

[0027] The length L of the wiring board 10 is 6000 mm or less. When handling the wiring board 10, selecting the appropriate length L of the wiring board 10 suppresses excessive deformation of the wiring board 10 (such as sagging or twisting due to its own weight), and as a result, work on the wiring board 10 is made easier. Specifically, as detailed below, two or fewer workers can easily handle the task of holding the wiring board 10.

[0028] Figure 4 is an explanatory diagram of the work involved in handling the wiring board 10. Specifically, the work involves inserting the end of the wiring board 10 into the connector 40 described later, or performing edge alignment to align the ends of multiple wiring boards 10. As illustrated in Figure 4, the work involves two workers, UR and UL, holding multiple wiring boards 10 that are stacked on top of each other. Workers UR and UL hold the multiple wiring boards 10 at a predetermined height with both hands, at positions spaced apart from each other laterally. Worker UR is positioned to the right of worker UL. The reason for holding the multiple wiring boards 10 at a predetermined height is to reduce the possibility of foreign matter adhering to each wiring board 10 due to the ends of the wiring boards 10 coming into contact with the ground, or to reduce the possibility of damage to the wiring boards 10 due to the ends of the wiring boards 10 coming into contact with the ground.

[0029] When workers UR and UL, both of standard build, hold each wiring board 10 with both hands while it is moderately flexed, the length L1 of the portion of the wiring board 10 located between their hands is approximately 2200 mm. Furthermore, it is assumed that the length L2 of the portion of the wiring board 10 located between worker UR's left hand and worker UL's right hand is approximately 1200 mm. The length L2 of this portion of the wiring board 10 was set to 1200 mm to satisfy the conditions that worker UR's left hand and worker UL's right hand do not come into contact, and that the portion of the wiring board 10 located between worker UR's left hand and worker UL's right hand does not come into contact with the ground even when flexed by its own weight. Note that workers UR and UL, both of standard build, are adults of any gender.

[0030] In the above state, workers UR and UL perform edge alignment by visually aligning the ends of the multiple wiring boards 10. As a result of the edge alignment, the positional error of the wiring boards 10 relative to the connector 40 can be reduced when inserting each wiring board 10 into the connector 40 described later. If the wiring boards 10 are attached to the connector 40 with positional errors, unnecessary stress may remain on the wiring boards 10. If residual stress and long-term vibrations act continuously on the wiring boards 10, malfunctions such as disconnection of the wiring 30 may occur. As a result of the edge alignment of the multiple wiring boards 10, the positional errors of the wiring boards 10 are reduced. Therefore, residual stress caused by positional errors is reduced, and consequently, malfunctions such as disconnection of the wiring 30 can be reduced.

[0031] In the edge alignment process, worker UR aligns the right edge of each wiring board 10 protruding to the right from his right hand, while worker UL aligns the left edge of each wiring board 10 protruding to the left from his left hand.

[0032] Specifically, workers UR and UL are required to align the edges of multiple wiring boards 10 within an error range of approximately 0.5 mm. To ensure a resolution of approximately 0.5 mm by visual inspection, the distance from the worker's eyes to the object must be within approximately 1000 mm. Note that a visual acuity (Japanese standard visual acuity) of 1.0 provides a resolution of approximately 1 arcminute (1 / 60 degree). A resolution of approximately 1 arcminute allows for the visual recognition of a positional error of 0.29 mm for an object 1000 mm away. With this level of resolution, even in practical situations, it is possible to visually recognize a positional error of approximately 0.5 mm for objects within 1000 mm.

[0033] In order to maintain a distance of 1000 mm or less from both of worker UR's eyes to the right edge of each wiring board 10, the distance L31 from worker UR's right hand to the right edge of each wiring board 10 must be maintained within 200 mm. Similarly, in order to maintain a distance of 1000 mm or less from both of worker UL's eyes to the left edge of each wiring board 10, the distance L32 from worker UL's left hand to the left edge of each wiring board 10 must be maintained within 200 mm.

[0034] The sum of the lengths of the parts of the wiring board 10 located between the hands of worker UR and worker UL (4400 mm = L1 × 2), the part of the wiring board 10 located between worker UR and worker UL (1200 mm = L2), the part of the wiring board 10 to the right of worker UR's right hand (200 mm = L31), and the part of the wiring board 10 to the left of worker UL's left hand (200 mm = L32) is 6000 mm. In other words, in a configuration where the length L of the wiring board 10 is 6000 mm or less, it is possible for two workers U (UR, UL) to properly perform edge alignment work while holding multiple stacked wiring boards 10.

[0035] In a more preferred embodiment, the length L of the wiring board 10 is 2500 mm or less. In this embodiment, the length L of the wiring board 10 is 2500 mm or less, which makes it easier for one worker to hold one or more wiring boards 10 with both hands at a predetermined height (for example, a height at which the wiring boards 10 do not touch the ground).

[0036] Other dimensions of the wiring board 10 will be explained with reference to Figure 1. First, the length Da of the terminal portion Ea in the Y-axis direction is selected according to the length L of the wiring board 10. Specifically, within the range between a predetermined lower limit (e.g., 3 mm) and a predetermined upper limit (e.g., 50 mm), the length Da of the terminal portion Ea increases as the length L of the wiring board 10 increases. The length Da of the terminal portion Ea is also expressed as the length of the connection terminal 31a in the Y-axis direction. Similarly, the length Db of the terminal portion Eb in the Y-axis direction is selected according to the length L of the wiring board 10. The length Db of the terminal portion Eb is also expressed as the length of the connection terminal 31b in the Y-axis direction.

[0037] On the other hand, the width W of the wiring board 10 is 5 mm or more and 550 mm or less. The width W is the dimension of the wiring board 10 in the direction in which the multiple wirings 30 are arranged side by side (the X-axis direction). That is, the width W of the wiring board 10 is the distance between the long sides when the wiring board 10 is held in a straight line. If the width W of the wiring board 10 is within the above range, it is easy for workers to hold or transport individual wiring boards 10.

[0038] The combination of length L and width W of the wiring board 10 is arbitrary. For example, a wiring board 10 having a length L of 10 mm and a width W of 5 mm, or a wiring board 10 having a length L of 6000 mm and a width W of 550 mm are examples. However, a configuration in which the width W of a wiring board 10 with a length L of 10 mm is any value between 5 mm and 550 mm, or a configuration in which the width W of a wiring board 10 with a length L of 6000 mm is any value between 5 mm and 550 mm.

[0039] A-2: Wiring structure 100 Figure 5 is a plan view of the wiring structure 100 in the first embodiment. The wiring structure 100 in the first embodiment is a long structure formed by connecting N (N is a natural number) wiring boards 10 described above in series in the direction of the Y axis. Specifically, the N wiring boards 10 are connected in series with each wiring 30 electrically connected between them. A single wiring is formed across the N wiring boards 10 by electrically connecting corresponding wirings 30 on each wiring board 10.

[0040] In the first embodiment, the number N of wiring boards 10 constituting the wiring structure 100 is 3 or more and 200 or less. In a more preferred embodiment, the number N of wiring boards 10 is 10 or more. With the above configuration, a long wiring structure 100 can be realized by connecting 10 or more wiring boards 10 in series with each other. In the first embodiment, the configuration (e.g., structure and shape) of the N wiring boards 10 constituting the wiring structure 100 is the same.

[0041] Let's focus on the nth (n is a natural number) wiring board 10 out of the N wiring boards 10 of the wiring structure 100. The (n+1)th wiring board 10 is connected to the nth wiring board 10 in the Y2 direction. Specifically, terminal Eb located in the Y2 direction of the nth wiring board 10 is connected to terminal Ea located in the Y1 direction of the (n+1)th wiring board 10. Also, the (n-1)th wiring board 10 is connected to the nth wiring board 10 in the Y1 direction. Specifically, terminal Ea located in the Y1 direction of the nth wiring board 10 is connected to terminal Eb located in the Y2 direction of the (n-1)th wiring board 10.

[0042] As described above, each wiring board 10 is plate-shaped and deformable. Therefore, the wiring structure 100 of the first embodiment has the advantage of being easier to lighten compared to, for example, a wire harness composed of bundles of multiple wires, as detailed below, and also reduces the space required for installation.

[0043] In conventional wire harnesses, each individual wire is covered with an insulating material such as polyvinyl chloride (PVC), whereas in the wiring structure 100, multiple wires 30 are insulated from each other by a narrow pitch. Therefore, in the wiring structure 100, the total amount of insulating material (first layer 21 and second layer 22) covering the multiple wires 30 is reduced compared to conventional wire harnesses. As a result of this reduction in total material, as mentioned above, weight reduction and a reduction in installation space are achieved.

[0044] Furthermore, while the cross-sectional diameter of multiple wire harnesses bundled together is 10 mm or more, the wiring structure 100 allows for a structure with electrical characteristics equivalent to those of a wire harness to be realized with a plate thickness of, for example, 3 mm or less. Moreover, in conventional wire harnesses, it was necessary to route the wires in a complex, detour-like shape to avoid interference with the wire harness itself or other wire harnesses, but with the wiring structure 100, routing is possible via the shortest path. Therefore, the wiring structure 100 allows for a reduction in the total amount of conductive material (e.g., copper) constituting the multiple wires 30 and the insulating material constituting the first layer 21 and the second layer 22. From these perspectives, as mentioned above, weight reduction and reduction in installation space are achieved.

[0045] As described above, the wiring structure 100 of the first embodiment is lighter and requires less installation space compared to conventional wire harnesses. Therefore, the wiring structure 100 can be suitably used as a substitute for wire harnesses in mobile devices such as electric vehicles.

[0046] As illustrated in Figure 5, (N-1) connectors 40 are used to connect N wiring boards 10. Any one connector 40 is a structure for electrically and mechanically connecting two wiring boards 10 that are adjacent to each other in the Y-axis direction among the N wiring boards 10. The connector 40 is a rigid structure with lower flexibility compared to each wiring board 10. For example, the flexibility index F of the wiring boards 10 is 2 mm / N or more as described above, while the flexibility index F of the connector 40 is less than 2 mm / N (for example, about 0.2).

[0047] Figure 6 is a cross-sectional view illustrating the configuration of each connector 40. In Figure 6, a connector 40 connecting wiring board 10_n1 and wiring board 10_n2 from among N wiring boards 10 is illustrated. Wiring boards 10_n1 and 10_n2 are two wiring boards 10 that are adjacent to each other in the direction of the Y axis. Specifically, wiring board 10_n2 is adjacent to wiring board 10_n1 in the Y2 direction. The same configuration as in Figure 6 is adopted for all possible combinations (a total of (N-1) sets) of selecting two mutually adjacent wiring boards 10 from N wiring boards 10. Note that wiring board 10_n1 is an example of a "first wiring board", and wiring board 10_n2 is an example of a "second wiring board".

[0048] As illustrated in Figure 6, the connector 40 includes a housing portion 41, a plurality of conductive members 42, a holder 43a, and a holder 43b. The housing portion 41 is a hollow structure that supports the plurality of conductive members 42, the holder 43a, and the holder 43b. Specifically, the housing portion 41 is formed in the shape of a rectangular tube with openings 41a and 41b.

[0049] In the process of connecting the wiring board 10_n1 and the wiring board 10_n2, as illustrated in Figure 6 as State 1, the terminal portion Eb of the wiring board 10_n1 is inserted into the opening 41a, and the terminal portion Ea of the wiring board 10_n2 is inserted into the opening 41b. Each of the multiple conductive members 42 corresponds to a different wiring 30 on each wiring board 10. That is, the same number of conductive members 42 as the wiring 30 installed on one wiring board 10 are arranged in parallel in the direction of the X axis.

[0050] Each of the multiple conductive members 42 is formed from a low-resistance conductive material. Examples of conductive materials used to form each conductive member 42 include metallic materials such as copper or aluminum, or alloy materials containing a low-resistance metal (e.g., copper or aluminum). Each conductive member 42 is a conductive member in which a support portion 45 and two connecting terminals 46a and 46b are integrally formed.

[0051] The support portion 45 is fixed to the housing portion 41. The connecting terminal 46a is a strip-shaped or linear terminal extending from the support portion 45 in the Y1 direction. The connecting terminal 46b is a strip-shaped or linear terminal extending from the support portion 45 in the Y2 direction. Each of the connecting terminals 46a and 46b is elastically deformable in the Z-axis direction relative to the support portion 45. Contact portions 47 are formed at the tips of the connecting terminals 46a and 46b. The contact portions 47 are formed of a metal with lower resistance than the connecting terminals 46a and 46b (for example, gold). Note that the contact portions 47 may be omitted.

[0052] The retainers 43a and 43b are structures that span the entire width of the wiring board 10. The retainer 43a is installed near the opening 41a in the housing portion 41. Specifically, the retainer 43a is supported in a manner that allows it to rotate about an axis of rotation along the X-axis. The retainer 43b is installed near the opening 41b in the housing portion 41. Specifically, the retainer 43b is supported in a manner that allows it to rotate about an axis of rotation along the X-axis.

[0053] State 2 in Figure 6 shows the state in which the wiring board 10_n1 and the wiring board 10_n2 are connected via the connector 40. When the terminal portion Eb of the wiring board 10_n1 is inserted into the opening 41a of the housing portion 41, the tip of the holder 43a is pressed by the terminal portion Eb and rotates clockwise. Consequently, the base end of the holder 43a rises and presses the wiring board 10_n1 (specifically the second layer 22) in the Z2 direction. The pressure from the base end of the holder 43a holds the terminal portion Eb of the wiring board 10_n1 in the connector 40. With the terminal portion Eb of the wiring board 10_n1 inserted into the opening 41a, the connection terminals 31b of each wiring 30 of the wiring board 10_n1 contact the connection terminals 46a (contact portions 47) of the conductive member 42 corresponding to the wiring 30. In other words, each wire 30 of the wiring board 10_n1 and the connection terminal 46a of each conductive member 42 are electrically connected. Furthermore, the connection terminal 46a is elastically deformed upward by being pressed by the terminal portion Eb of the wiring board 10_n1. Therefore, the connection terminal 46a of the conductive member 42 is maintained in a state of being pressed against the connection terminal 31b.

[0054] Similarly, when the terminal portion Ea of the wiring board 10_n2 is inserted into the opening 41b of the housing portion 41, the wiring board 10_n2 is held in the connector 40 by the rotation of the holder 43b. With the terminal portion Ea of the wiring board 10_n2 inserted into the opening 41b, the connection terminal 31a of each wire 30 of the wiring board 10_n2 contacts the connection terminal 46b (contact portion 47) of the conductive member 42 corresponding to that wire 30. In other words, each wire 30 of the wiring board 10_n1 and the connection terminal 46a of each conductive member 42 are electrically connected. As described above, in the first embodiment, the wires 30 of the wiring board 10_n1 and the wires 30 of the wiring board 10_n2 are electrically connected via the conductive member 42 of the connector 40.

[0055] Next, we consider the connection resistance ratio R of the wiring structure 100. The connection resistance ratio R is the ratio of the connection resistance Rc to the total resistance Rt between both ends of the wiring structure 100 (R = Rc / Rt). The total resistance Rt is the electrical resistance of a single wire 30 that spans both ends of the wiring structure 100. On the other hand, the connection resistance Rc is the sum of the electrical resistances at the joints of two adjacent wiring boards 10 out of the N wiring boards 10, over the entire wiring structure 100. Specifically, in the first embodiment, the connection resistance Rc is the sum of the electrical resistance of the conductive member 42 in each connector 40 and the contact resistance of each wire 30 (connection terminal 31a and connection terminal 31b) to the conductive member 42, for all connectors 40 of the wiring structure 100. That is, the sum of the total electrical resistance of the wires 30 across the N wiring boards 10 and the connection resistance Rc corresponds to the total resistance Rt. In the first embodiment, the connection resistance ratio R of the wiring structure 100 is 19 PPB (Parts Per Billion) or more and 60.417% or less.

[0056] The connection resistance ratio R can be expressed, for example, by the following formula (1).

number

[0057] In equation (1), the symbol ρ0 represents the resistivity [Ω·m] of the conductive material constituting the wiring 30. The symbol ρc represents the resistivity [Ω·m] at the point where two adjacent wiring boards 10 are connected (hereinafter referred to as the "connection point"). In equation (1), the symbol L0 represents the total length of the wiring 30 (the sum across N wiring boards 10), and the symbol A0 represents the cross-sectional area of ​​the wiring 30. Also, in equation (1), the symbol Lk represents the length of the k-th connection point, and the symbol Ak represents the cross-sectional area at the k-th connection point. The denominator of equation (1) corresponds to the total resistance Rt between both ends of the wiring structure 100, and the numerator of equation (1) corresponds to the connection resistance Rc, which is the sum of the electrical resistances across K connection points.

[0058] In configurations where the connection resistance ratio R exceeds 60.417%, a significant voltage drop occurs at each connection point. This increased voltage drop at each connection point can lead to unstable power supply to the device to which the wiring structure 100 is connected, potentially hindering the normal operation of the device.

[0059] For example, consider a circuit that operates on a 12V power supply voltage as an in-vehicle circuit installed in an electric vehicle. If the connection resistance ratio R is 60.417%, a voltage drop of approximately 3V may occur at the connection point. In this situation, even if a 12V power supply voltage is output from the power supply unit, the actual power supply voltage supplied to the in-vehicle circuit is 9V. Normally, a margin of ±3V is ensured for the power supply voltage of an in-vehicle circuit, but even considering this margin, the power supply voltage may fall below the acceptable range in the above situation. For these reasons, a configuration in which the connection resistance ratio R is 60.417% or less is preferable.

[0060] For example, the resistivity ρ0 of the copper (Cu) that makes up the wiring 30 is 1.68 × 10 -8 Assume a wiring structure 100 with 30 connection points using connectors 40, each with a contact resistance of 0.1Ω (Ω·m). To keep the connection resistance ratio R below 60.417%, the cross-sectional area of ​​the wiring 30 must be 1050 μm². 2It is necessary to meet the above requirements. For example, if the width of wiring 30 is 30 μm, the thickness of wiring 30 must be 35 μm (so-called 1 oz thickness) or more.

[0061] Furthermore, we assume that the wiring structure 100 is used for the communication of relatively low-frequency signals (for example, around 20 kHz). For example, I 2 Examples of serial communication include C (Inter-Integrated Circuit), CAN (Controller Area Network), and UART (Universal Asynchronous Receiver / Transmitter). Even when the wiring structure 100 is used for communication, a voltage drop caused by an increase in the impedance of the wiring 30 may result in a decrease in signal quality or malfunction of the communication device. Since low-frequency impedance is approximately equivalent to DC resistance, a configuration in which the connection resistance ratio R is 60.417% is preferable even when the wiring structure 100 is used for low-frequency signal communication.

[0062] As described above, in the first embodiment, the wiring structure 100 is constructed by connecting three to 200 separate wiring boards 10 in series. Therefore, it is easier to handle compared to a single wiring board formed in a very long length. For example, according to the first embodiment, it is possible to easily transport or store the individual wiring boards 10 in a lightweight state. In addition, since the need to wind them onto a core material during transport or storage is reduced, the possibility of each wiring board 10 developing a curl is reduced.

[0063] In conventional manufacturing of printed circuit boards, it is common practice to manufacture individual printed circuit boards that are long and continuous, extending to the length required for the intended use of the board (hereinafter referred to as the "required length"). The following are some possible reasons why printed circuit boards are manufactured in such long lengths:

[0064] First, it's important to understand that circuit boards (PCBs) are not general-purpose products usable for a variety of applications, but rather specialized items (so to speak, made-to-order products) that are individually designed and manufactured according to specific applications or specifications. As such, since conventional PCBs are designed and manufactured as specialized items, there is no rational reason to deliberately divide such a PCB into multiple parts for manufacturing.

[0065] Furthermore, long-length wiring boards are manufactured using, for example, rolls of conductive sheets that constitute the wiring and rolls of resin film that constitute the equipment. Specifically, various processing steps are sequentially performed on the conductive sheets and resin film that are continuously fed from the rolls on the manufacturing line. If the wiring board is deliberately divided into multiple parts, the number of division steps for the wiring board increases, as does the effort required to handle each wiring board individually. Therefore, the series of processes on the manufacturing line using the rolls of conductive sheets and resin film are hindered, making it difficult to smoothly manufacture wiring boards of the required length.

[0066] Due to the circumstances described above, conventional wiring boards are manufactured as single, continuous wiring boards that extend over the required length. Therefore, the feature of constructing a wiring structure 100 by connecting three or more separate wiring boards 10 in series with each other is not something that can be inferred from conventional wiring boards.

[0067] Furthermore, in the first embodiment, since the wiring board 10_n1 and the wiring board 10_n2 are connected by a connector 40, the work of connecting N wiring boards 10 to each other can be simplified. Specifically, by repeating the simple operation of inserting the terminal portion Eb of the wiring board 10_n1 into the opening 41a of the connector 40 and inserting the terminal portion Ea of the wiring board 10_n2 into the opening 41b of the connector 40 for (N-1) connectors 40, a wiring structure 100 made up of N wiring boards 10 can be manufactured.

[0068] In the first embodiment, the connection resistance ratio R, which is the ratio of the connection resistance Rc to the total resistance Rt between both ends of the wiring structure 100, is suppressed to 60.417% or less. Therefore, the increase in electrical resistance caused by the connection of N wiring boards 10 can be effectively suppressed.

[0069] B: Second Embodiment A second embodiment will now be described. For elements whose function is the same as in the first embodiment in each of the embodiments described below, the same reference numerals as in the first embodiment will be used, and detailed descriptions of each will be omitted as appropriate.

[0070] In the second embodiment, as in the first embodiment, the wiring structure 100 is constructed by connecting N wiring boards 10 (where N is a natural number between 3 and 200) in series. The configuration of each wiring board 10 is the same as in the first embodiment. The dimensions of each wiring board 10 are also the same as in the first embodiment.

[0071] Figure 7 is a plan view of the wiring structure 100 in the second embodiment, and Figure 8 is a cross-sectional view of the line cc in Figure 7. As illustrated in Figures 7 and 8, the terminal portion Eb of each wiring board 10 (for example, wiring board 10_n1 in Figure 8) and the terminal portion Ea of an adjacent wiring board 10 in the Y2 direction of the same wiring board 10 (for example, wiring board 10_n2 in Figure 8) face each other in the Z-axis direction. That is, in the second embodiment, two wiring boards 10 (10_n1, 10_n2) that are adjacent to each other in the Y-axis direction partially overlap in a plan view.

[0072] Therefore, each wire 30 (connection terminal 31a) of terminal Eb on each wiring board 10 and each wire 30 (connection terminal 31b) of terminal Ea on another wiring board 10 adjacent to that wiring board 10 face each other. For example, in Figure 8, each wire 30 of terminal Eb on wiring board 10_n1 and each wire 30 of terminal Ea on wiring board 10_n2 face each other. As can be understood from the above explanation, in the second embodiment, the front and back sides of the wiring boards 10 are reversed between two adjacent wiring boards 10. Note that any one wiring board 10_n1 of the wiring structure 100 is an example of a "first wiring board", and another wiring board 10_n2 adjacent to that wiring board 10 in the Y-axis direction is an example of a "second wiring board".

[0073] As illustrated in Figure 8, terminal Ea of one wiring board 10 and terminal Eb of an adjacent wiring board 10 are joined by an anisotropic conductive film 48. The anisotropic conductive film 48 is a conductive adhesive sheet in which a large number of fine conductive particles are dispersed. Therefore, each wiring 30 of the wiring board 10 is electrically connected to each other in a facing state. Note that the method of connecting adjacent wiring boards 10 is not limited to the above examples. Specifically, the facing wirings 30 may be connected, for example, by solder or ultrasonic waves.

[0074] As illustrated in Figure 7, the portion where two adjacent wiring boards 10 overlap in a plan view may be held by a holding member 49. The holding member 49 is a clip that clamps the overlapping portion (connecting portion) of the two wiring boards 10 in the Z-axis direction. With the above configuration, the possibility of each wiring board 10 constituting the wiring structure 100 separating can be reduced.

[0075] The same effects as in the first embodiment are achieved in the second embodiment. In the second embodiment, the multiple wires 30 of each wiring board 10 are electrically connected in a state where they face each other. Therefore, the weight of the wiring structure 100 can be reduced compared to a configuration in which a connector 40 is used to connect each wiring board 10.

[0076] C: Third Embodiment In the first and second embodiments, examples were given in which the configurations of the N wiring boards 10 constituting the wiring structure 100 are common. In the third embodiment, the N wiring boards 10 constituting the wiring structure 100 include multiple types of wiring boards 10 with different configurations. Specifically, the configuration of one wiring board 10_n1 among the N wiring boards 10 is different from the configuration of one wiring board 10_n2 other than wiring board 10_n1. In the first and second embodiments, two adjacent wiring boards 10 were referred to as wiring board 10_n1 and wiring board 10_n2, but in the third embodiment, wiring boards 10_n1 and wiring board 10_n2 do not need to be adjacent to each other.

[0077] As described above, in the third embodiment, N wiring boards 10, including wiring boards 10_n1 and 10_n2 with different configurations, are interconnected. Therefore, compared to a configuration in which the N wiring boards 10 constituting the wiring structure 100 have a common configuration, the configuration of the wiring structure 100 is diversified. In other words, it is possible to provide a wiring structure 100 that can meet diverse requirements.

[0078] The following provides specific examples of the configurations of several types of wiring boards 10 (10a to 10i). The basic configuration of each wiring board 10 described below is the same as the configuration described above, referring to Figures 1 to 3. The specific configurations of each of the several types of wiring boards 10 will be explained, focusing on the configurations that differ from the basic configuration described above.

[0079] C-1: Configuration a / Wiring board 10a Figure 9 is a plan view of the wiring board 10a. As illustrated in Figure 9, the planar shape of the wiring board 10a is such that the end located in the Y2 direction branches into multiple parts. The wiring board 10a is used as one of the end (1st and Nth) wiring boards 10 among the N wiring boards 10 that make up the wiring structure 100.

[0080] As illustrated in Figure 9, the wiring board 10a includes a base portion 241 and a plurality of branch portions 242 in a plan view. The base portion 241 is a single portion that extends across the entire width of the wiring board 10a. The plurality of branch portions 242 are portions that extend in the Y2 direction from the edge of the base portion 241 located in the Y2 direction. As can be understood from the above description, the "branching" of the wiring board 10a means a shape in which one end of each of the plurality of branch portions 242 is connected to one another, and the other end of each is physically separated. Each "branched" portion (branch portion 242) is deformable in different directions.

[0081] Multiple branch sections 242 are arranged in the direction of the X axis. Each of the multiple branch sections 242 corresponds to a different wiring 30 on the wiring board 10a. That is, the same number of branch sections 242 as the wiring 30 on the wiring board 10a are formed. The wiring 30 corresponding to each branch section 242 extends in the direction of the Y axis so as to be continuous from the base section 241 to the branch section 242. The end of each branch section 242 in the Y2 direction is a terminal section Eb where the end of the wiring 30 (connection terminal 31b) is exposed. Note that multiple wirings 30 may be formed in each branch section 422.

[0082] As illustrated in Figure 10, connection pins 243 may be installed on the terminal Eb of each branch section 242. The connection pins 243 are, for example, conductors crimped and fixed to the terminal Eb of each branch section 242. Also, as illustrated in Figure 11, end connectors 244 may be installed on the terminal Eb of a predetermined number (one or more) of branch sections 242. The end connectors 244 are interfaces for electrically connecting the wiring structure 100 to an external device.

[0083] Of the N wiring boards 10 that make up the wiring structure 100, one wiring board 10_n1 is composed of a planar wiring board 10a that branches into multiple parts (branching sections 242). On the other hand, one wiring board 10_n2 other than wiring board 10_n1 in the wiring structure 100 does not have branches formed. In other words, the configuration of wiring board 10_n1 and the configuration of wiring board 10_n2 are different. By using the configuration with wiring board 10a, the planar shape of the wiring structure 100 can be diversified compared to a configuration in which no branches are formed on any of the N wiring boards 10.

[0084] C-2: Configuration b / wiring board 10b Figure 12 is a plan view of the wiring board 10b. As illustrated in Figure 12, a low-strength portion 25 is formed on the wiring board 10b along the Y-axis. The low-strength portion 25 is a part of the base material 20 that has lower mechanical strength than other parts. The low-strength portion 25 extends from the terminal portion Eb of the base material 20 in the Y1 direction to partway along the base material 20. In a plan view, the low-strength portion 25 is located within the spacing between two adjacent wirings 30 in the X-axis direction.

[0085] As illustrated in Figure 13, the wiring board 10b can be divided along the low-strength portion 25. The planar shape of the wiring board 10b after division is a branched shape originating from the Y1 direction end of the low-strength portion 25. As described above, the wiring board 10b can be mounted in a state where the base material 20 is continuous in the low-strength portion 25 (Figure 12) and in a state where the base material 20 is divided in the low-strength portion 25 (Figure 13).

[0086] As illustrated in Figure 12, the low-strength portion 25 of the wiring board 10b includes a plurality of divisions 251 arranged at intervals from one another in the direction of the Y axis. Figure 14 is a cross-sectional view of the line dd in Figure 12. As illustrated in Figure 14, each of the plurality of divisions 251 is a bottomed hole formed in the base material 20. Specifically, each division 251 is a groove formed across the first layer 21 and the bonding material 23. The divisions 251 do not reach the second layer 22. Each division 251 is formed in an elongated shape along the Y axis. As illustrated above, the low-strength portion 25 of the wiring board 10b is a perforation with a plurality of cuts (divisions 251) arranged in the direction of the Y axis.

[0087] The method for forming the divisions 251 in the wiring board 10b is arbitrary. For example, each division 251 can be formed by cutting using a cutting tool such as a cutter or drill. Alternatively, each division 251 may be formed by laser processing, for example, by irradiating the wiring board 10b with a laser. Each division 251 may also be a through hole extending from the first layer 21 to the bonding material 23 to the second layer 22.

[0088] Of the N wiring boards 10 that make up the wiring structure 100, one wiring board 10_n1 is composed of a wiring board 10b in which a low-strength portion 25 is formed along the direction in which the multiple wirings 30 extend (i.e., the Y-axis direction). On the other hand, one wiring board 10_n2 other than wiring board 10_n1 in the wiring structure 100 does not have a low-strength portion 25 formed thereon. In other words, the configuration of wiring board 10_n1 and the configuration of wiring board 10_n2 are different. With the configuration using wiring board 10b, the planar shape of the wiring structure 100 can be diversified by dividing the wiring board 10_n1 along the low-strength portion 25.

[0089] C-3: Configuration c / wiring board 10c Figure 15 is a plan view of the wiring board 10c. As illustrated in Figure 15, the wiring board 10c has a plurality of slits 26 formed along the Y-axis. Each of the plurality of slits 26 is a through hole (notch) that penetrates the base material 20 in the Z-axis direction. Specifically, each slit 26 penetrates the first layer 21, the second layer 22, and the bonding material 23.

[0090] Multiple slits 26 are formed in a portion of the wiring board 10c in the Y-axis direction (hereinafter referred to as the "deformed portion 261"). The multiple slits 26 are arranged side by side with intervals between them in the X-axis direction. In a plan view, each slit 26 is located within the interval between two adjacent wirings 30 in the X-axis direction. In Figure 15, a configuration in which a slit 26 is formed at the interval between each wiring 30 is illustrated, but one slit 26 may be formed for each pair of two or more adjacent wirings 30.

[0091] The method for forming the slits 26 in the substrate 20 is arbitrary. For example, each slit 26 may be formed by cutting using a cutting tool such as a grinder or cutter. Alternatively, each slit 26 may be formed by laser processing, for example, by irradiating the substrate 20 with a laser.

[0092] As described above, multiple slits 26 are formed in the wiring board 10c. That is, the mechanical strength of the deformable portion 261 of the wiring board 10c is lower than the mechanical strength of the other parts of the wiring board 10c. Therefore, it is possible to deform the wiring board 10c into various shapes in the deformable portion 261.

[0093] As illustrated in Figure 16, the wiring board 10c can be twisted in the deformable portion 261. Specifically, the portion of the base material 20 located in the Y1 direction relative to the deformable portion 261 can rotate about an axis parallel to the Y axis relative to the portion of the base material 20 located in the Y2 direction relative to the deformable portion 261.

[0094] As illustrated in Figure 17, it is possible to join the wiring boards 10c at the deformable portion 261. Specifically, the width of the deformable portion 261 of the base material 20 can be reduced compared to the width of other parts of the base material 20. That is, the wiring boards 10c can be bundled at the deformable portion 261. With the width of the deformable portion 261 reduced as described above, the wiring boards 10c can be deformed in the in-plane direction at the deformable portion 261, as illustrated in Figure 18. Specifically, it is possible to easily bend the wiring boards 10c in the in-plane direction at the deformable portion 261 such that a portion of the base material 20 located in the Y1 direction relative to the deformable portion 261 and a portion located in the Y2 direction relative to the deformable portion 261 form a predetermined angle.

[0095] Of the N wiring boards 10 that make up the wiring structure 100, one wiring board 10_n1 is composed of a wiring board 10c in which multiple slits 26 are formed along the direction in which multiple wirings 30 extend (i.e., the Y-axis direction). On the other hand, one wiring board 10_n2 other than wiring board 10_n1 in the wiring structure 100 does not have slits 26 formed therein. In other words, the configuration of wiring board 10_n1 and the configuration of wiring board 10_n2 are different. With the configuration using wiring board 10c, the planar shape of the wiring structure 100 can be diversified by deforming wiring board 10_n1 using the multiple slits 26.

[0096] C-4: Configuration d / wiring board 10d Figure 19 is a plan view of the wiring board 10d. As illustrated in Figure 19, the planar shape of the wiring board 10d includes one or more bent sections (274, 275). Specifically, the wiring board 10d includes a section 271 extending in the Y2 direction from the terminal section Ea, a section 272 extending in the X-axis direction from the Y2 end of section 271, and a section 273 extending in the Y2 direction from the end of section 272. That is, the wiring board 10d includes a bent section 274 between section 271 and section 272, and a bent section 275 between section 272 and section 273.

[0097] Of the N wiring boards 10 that make up the wiring structure 100, one wiring board 10_n1 is composed of a wiring board 10d that includes one or more bent sections (274, 275). On the other hand, one wiring board 10_n2 in the wiring structure 100, other than wiring board 10_n1, is a straight wiring board 10 that does not include any bent sections. In other words, the configuration of wiring board 10_n1 and the configuration of wiring board 10_n2 are different. By using a configuration that utilizes wiring board 10d, the planar shape of the wiring structure 100 can be diversified.

[0098] C-5: Configuration e / Wiring board 10e Figure 20 is a plan view of the wiring board 10e, and Figure 21 is a cross-sectional view of line ee in Figure 20. As illustrated in Figures 20 and 21, the plurality of wirings 30 of the wiring board 10e include a plurality of first wirings 35 and a plurality of second wirings 36. The plurality of first wirings 35 are three wirings 30 located in the X1 direction from among the plurality of wirings 30, and the plurality of second wirings 36 are three wirings 30 located in the X2 direction from among the plurality of wirings 30.

[0099] The wiring width ω1 of each first wiring 35 and the wiring width ω2 of each second wiring 36 are different. Specifically, the wiring width ω1 is greater than the wiring width ω2. The number of each of the first wiring 35 and second wiring 36 may be changed as desired.

[0100] In the wiring structure 100, of the N wiring boards 10 that make up the wiring structure 100, the multiple wirings 30 on one wiring board 10_n1 include a first wiring 35 and a second wiring 36 with different wiring widths. On the other hand, the multiple wirings 30 on one wiring board 10_n2 other than wiring board 10_n1 in the wiring structure 100 have the same wiring width. In other words, the configuration of wiring board 10_n1 and the configuration of wiring board 10_n2 are different. With the configuration using wiring board 10d, different powers can be transmitted in parallel using the first wiring 35 and the second wiring 36.

[0101] C-6: Configuration f / wiring board 10f Figure 22 is a plan view of the wiring board 10f. As illustrated in Figure 22, the wiring board 10f includes a plurality of electronic components 51. The electronic components 51 are various mounted components placed on the surface of the substrate 20. Specifically, the electronic components 51 are bonded to the outer surface S12 of the first layer 21. For example, passive elements or active elements are exemplified as electronic components 51. Passive elements are, for example, resistive elements, capacitive elements, or inductive elements (coils). Active elements are, for example, transistor elements or diode elements. The total number of electronic components 51 placed on the wiring board 10f may be arbitrarily changed.

[0102] Each electronic component 51 is electrically connected to one or more wirings 30 via conductive holes (contact holes) formed in the first layer 21 of the substrate 20. In the above description, an example has been given in which the electronic components 51 are mounted on the first layer 21, but the electronic components 51 may also be mounted on the second layer 22.

[0103] Of the N wiring boards 10 that make up the wiring structure 100, one wiring board 10_n1 is a wiring board 10f that includes an electronic component 51. On the other hand, one wiring board 10_n2 in the wiring structure 100, other than wiring board 10_n1, does not include an electronic component 51. In other words, the configuration of wiring board 10_n1 and the configuration of wiring board 10_n2 are different. With the configuration using wiring board 10f, it is possible to mount various functions using the electronic component 51 on the wiring structure 100.

[0104] C-7: Configuration g / wiring board 10g Figure 23 is a plan view of the wiring board 10g. As illustrated in Figure 23, the wiring board 10g includes an expandable / contractible portion 28. The expandable / contractible portion 28 is the part of the wiring board 10g that is expandable / contractible in the direction of the Y axis. Specifically, the expandable / contractible portion 28 is less rigid (i.e., more flexible) than the other parts of the wiring board 10g and is easily deformed in the direction of the Y axis.

[0105] The expandable section 28 of the first embodiment includes a plurality of bellows sections 281 that are elongated in the direction of the Y axis. The plurality of bellows sections 281 are arranged side by side with spacing between them in the direction of the X axis. In the first embodiment, a configuration in which the wiring board 10g includes four bellows sections 281 is illustrated, but the number of bellows sections 281 (number of wires 30) is arbitrary.

[0106] Each of the multiple bellows sections 281 is a section in which parts bent in opposite directions in a plan view are alternately arranged in the direction of the Y axis (i.e., meander shape). The planar shape of each bellows section 281 can also be described as a wave shape. Each bellows section 281 is composed of a stack of a first layer 21, a second layer 22, and wiring 30. The configuration (e.g., shape and dimensions) of the multiple bellows sections 281 is common. Note that each bellows section 281 may contain multiple wirings 30.

[0107] As illustrated in Figure 24, the expandable portion 28 extends in the Y-axis direction as the bending angle of each part of each bellows section 281 increases. On the other hand, the expandable portion 28 contracts in the Y-axis direction as the bending angle of each part of the bellows section 281 decreases. As described above, in the first embodiment, since the expandable portion 28 includes bellows sections 281, an expandable portion 28 that can be easily deformed by the action of an external force can be easily realized.

[0108] Of the N wiring boards 10 that make up the wiring structure 100, one wiring board 10_n1 is a wiring board 10g that includes the expandable portion 28 described above. On the other hand, one wiring board 10_n2, other than wiring board 10_n1 in the wiring structure 100, does not include the expandable portion 28. In other words, the configuration of wiring board 10_n1 and the configuration of wiring board 10_n2 are different. With the configuration using wiring board 10g, by expanding and contracting the expandable portion 28, it is possible to accommodate various shapes of the installation surface on which the wiring structure 100 is installed.

[0109] C-8: Configuration h / wiring board 10h Figure 25 is a plan view of the wiring board 10h. As illustrated in Figure 25, the wiring board 10h includes a flexible protective member 52. The protective member 52 is a plate-shaped member that protects the base material 20 by covering a portion of the wiring board 10h. Specifically, the protective member 52 is installed on the first layer 21 of the base material 20. Alternatively, the protective member 52 may be installed on the second layer 22 of the base material 20, or on both the first layer 21 and the second layer 22.

[0110] The protective member 52 is formed from an insulating material. Examples of insulating materials used for the protective member 52 include polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyvinyl chloride (PVC), or liquid crystal polymer (LCP). The protective member 52 is flexible, just like the base material 20. Therefore, the protective member 52 deforms together with the base material 20. The position on the base material 20 where the protective member 52 is installed and the planar shape of the protective member 52 can be arbitrarily changed.

[0111] Of the N wiring boards 10 that make up the wiring structure 100, one wiring board 10_n1 is a wiring board 10h that includes a protective member 52. On the other hand, one wiring board 10_n2 in the wiring structure 100, other than wiring board 10_n1, is a wiring board 10 that does not include a protective member 52. In other words, the configuration of wiring board 10_n1 and the configuration of wiring board 10_n2 are different. With the configuration using wiring board 10h, for example, damage to the base material 20 caused by collision with an external element can be suppressed by the protective member 52.

[0112] C-9: Configuration i / wiring board 10i The wiring board 10 illustrated in Figure 1 includes a terminal portion Ea that protrudes in the Y1 direction from the Y1 direction end of the first layer 21 in the second layer 22, and a terminal portion Eb that protrudes in the Y2 direction from the Y2 direction end of the first layer 21 in the second layer 22. Therefore, as illustrated in Figure 3, both connection terminals 31a and 31b are located in the Z2 direction relative to the second layer 22. That is, connection terminals 31a and 31b are formed in the same direction along the Z axis when viewed from the base material 20.

[0113] Figure 26 is a plan view of the wiring board 10i. Figure 27 is a cross-sectional view of the ff line in Figure 26. At terminal Ea of the wiring board 10i, the first layer 21 is removed. That is, similar to the wiring board 10 illustrated in Figure 1, terminal Ea is the portion of the second layer 22 that protrudes in the Y1 direction from the Y1 direction end of the first layer 21. On the other hand, at terminal Eb of the wiring board 10i, the second layer 22 is removed. That is, as illustrated in Figures 26 and 27, terminal Eb is the portion of the first layer 21 that protrudes in the Y2 direction from the Y2 direction end of the second layer 22.

[0114] As illustrated in Figures 26 and 27, a connection terminal 31a is formed on the end of each wiring 30 that is exposed to terminal Ea, and a connection terminal 31b is formed on the end of each wiring 30 that is exposed to terminal Eb. Therefore, in the wiring board 10i, the connection terminal 31a is located in the Z2 direction relative to the second layer 22, and the connection terminal 31b is located in the Z1 direction relative to the first layer 21. In other words, in the wiring board 10i, the connection terminals 31a and 31b are formed in opposite directions along the Z axis when viewed from the base material 20.

[0115] Of the N wiring boards 10 that make up the wiring structure 100, one wiring board 10_n1 is the wiring board 10i exemplified above. That is, the connection terminals 31a and 31b are located in opposite directions along the Z-axis when viewed from the base material 20. On the other hand, one wiring board 10_n2 of the wiring structure 100, other than wiring board 10_n1, is the wiring board 10 exemplified in Figure 1. That is, the connection terminals 31a and 31b are located in the same direction along the Z-axis when viewed from the base material 20. As illustrated above, the configuration of wiring board 10_n1 and the configuration of wiring board 10_n2 are different.

[0116] With the configuration using the wiring board 10i, as illustrated in Figure 28, it is possible to connect multiple wiring boards 10 in various ways. In the configuration illustrated in Figure 8, two adjacent wiring boards 10 have their front and back sides reversed. That is, for each odd-numbered wiring board 10 among the N wiring boards 10, the first layer 21 of the base material 20 is positioned in the Z2 direction relative to the second layer 22, and for each even-numbered wiring board 10, the first layer 21 of the base material 20 is positioned in the Z1 direction relative to the second layer 22. In contrast to the configuration in Figure 8, with the configuration using the wiring board 10i, as illustrated in Figure 28, it is possible to connect all the wiring boards 10 with the first layer 21 of the base material 20 positioned in the Z2 direction relative to the second layer 22.

[0117] C-10: Supplementary information regarding the third embodiment In the above description, each of the multiple types of wiring boards 10 (10a to 10i) has been described individually, but the N wiring boards 10 constituting the wiring structure 100 may include two or more types of wiring boards 10 from the multiple types of wiring boards 10 (10a to 10i) exemplified above. The wiring structure 100 of the third embodiment may include the standard wiring boards 10 exemplified in the first and second embodiments (Figures 1 to 8), or it may be composed of two or more types of wiring boards 10 selected from the multiple types of wiring boards 10 (10a to 10i).

[0118] D: Variant The following are examples of specific modifications that may be added to the embodiments exemplified above. Two or more embodiments may be arbitrarily selected from the following examples and merged as appropriate, provided they do not contradict each other.

[0119] (1) In the above-described embodiments, an example was given in which N wiring boards 10 are connected in series, but one or more wiring boards 10 may be connected in parallel to the N wiring boards 10 that are connected in series with each other.

[0120] For example, as illustrated in Figure 29, wiring boards 10_1 and 10_2 may be stacked in the Z-axis direction and connected to wiring board 10_3. Wiring boards 10_1 and 10_3 are connected in series, and wiring board 10_2 is connected in parallel to wiring board 10_1. Three or more wiring boards 10 may be stacked.

[0121] As illustrated in Figure 30, wiring boards 10_1 and 10_2 may be connected to wiring board 10_3 in a parallel configuration along the X-axis. Wiring boards 10_1 and 10_3 are connected in series, and wiring board 10_2 is connected in parallel to wiring board 10_1. Three or more wiring boards 10 may be arranged in parallel.

[0122] (2) In the embodiments described above, the substrate 20 of the wiring board 10 is shown as having a laminate of a first layer 21 and a second layer 22, but the configuration of the substrate 20 is not limited to the above examples and may be changed as desired. For example, one of the first layer 21 and the second layer 22 may be omitted. In addition, each wiring board 10 may be a multilayer substrate in which multiple wiring layers and insulating layers are alternately laminated. Each wiring layer includes multiple wirings 30 as exemplified in each embodiment described above.

[0123] (3) The following characteristics were exemplified in each of the above forms. [Feature 1] A wiring structure 100 is formed by connecting N wiring boards 10 (where N is a natural number between 3 and 200). [Feature 2] Each of the N wiring boards 10 that make up the wiring structure 100 has a length of 10 mm or more and 6000 mm or less. [Feature 3] Of the N wiring boards 10 that make up the wiring structure 100, the configuration of wiring board 10_n1 and the configuration of wiring board 10_n2 are different.

[0124] Each of the features 1 through 3 may be adopted independently of each other. For example, for features 2 and 3, the configuration in which the number of wiring boards 10 N is 3 or more and 200 or less (feature 1) is not required. That is, feature 2 or feature 3 may be adopted in a configuration in which the number of wiring boards 10 N is 2. Also, feature 2 or feature 3 is not required in feature 1 and may be omitted.

[0125] (4) The notation "nth" (where n is a natural number) in this application is used solely as a formal and convenient label to distinguish each element in notation and has no substantive meaning whatsoever. Therefore, there is no room for restrictive interpretation of the position or manufacturing order of each element based on the notation "nth".

[0126] E: Addendum From the forms exemplified above, the following configuration can be understood, for example.

[0127] E-1: Pattern A The requirements for printed circuit boards are becoming more diverse. For example, there are cases where printed circuit boards that are significantly longer than those used in small electronic devices such as portable information devices are required. However, printed circuit boards formed to be extremely long are practically difficult to handle. For example, the excessive weight of the printed circuit board makes transportation difficult. Also, if we consider a situation where a long printed circuit board is transported or stored while wound around a core material, it becomes necessary to straighten the remaining coiling in the printed circuit board at the product mounting stage. Taking these circumstances into consideration, one aspect of this disclosure (Aspect A) aims to provide a wiring structure that is easy to handle.

[0128] A wiring structure according to one aspect of the present disclosure (Aspect A1) comprises a flexible plate-shaped base material and N wiring boards (where N is a natural number between 3 and 200) each containing a plurality of wirings arranged side by side on the base material, connected in series between the N wiring boards, with each of the plurality of wirings being electrically connected. In this aspect, the wiring structure is formed by connecting 3 to 200 wiring boards, each composed separately, in series. Therefore, it is easier to handle compared to a single wiring board formed in a very long length. For example, it is possible to easily transport or store the individual wiring boards in a separated state. In addition, since the need to wind the wiring onto a core material during transport or storage is reduced, the possibility of each wiring board developing a curl is reduced.

[0129] In a specific example of embodiment A1 (embodiment A2), a connector is further provided to connect the first wiring board and the second wiring board among the N wiring boards. In the above embodiment, since the first wiring board and the second wiring board are connected by a connector, the work of connecting multiple wiring boards to each other can be made easier.

[0130] In a specific example of Embodiment A2 (Embodiment A3), the connector includes a plurality of conductive members that electrically connect the plurality of wirings on the first wiring board and the plurality of wirings on the second wiring board. According to the above embodiment, the wirings on each wiring board can be electrically connected by the simple operation of connecting each wiring on the first wiring board to a conductive member of the connector and each wiring on the second wiring board to a conductive member of the connector.

[0131] In a specific example of Embodiment A1 (Embodiment A4), the plurality of wirings on the first wiring board among the N wiring boards and the plurality of wirings on the second wiring board among the N wiring boards are electrically connected in a mutually opposing state. In the above embodiment, the plurality of wirings on the first wiring board and the plurality of wirings on the second wiring board are electrically connected in a mutually opposing state. Therefore, compared to a configuration in which a connector is used to connect the first wiring board and the second wiring board, for example, the weight of the wiring structure can be reduced.

[0132] In any specific example of embodiments A1 to A4 (embodiment A5), the ratio of the connection resistance, which is the sum of the electrical resistances at the joints of two adjacent wiring boards among the N wiring boards, to the total resistance between both ends of the wiring structure, is 60.417% or less. In the above embodiments, the ratio of the connection resistance at the joints to the total resistance of the wiring structure is suppressed to 60% or less, thereby suppressing the increase in electrical resistance caused by the connection of multiple wiring boards.

[0133] In any specific example of embodiments A1 to A5 (embodiment A6), the number N of the wiring boards is 10 or more. In the above embodiments, a long wiring structure can be realized by connecting 10 or more wiring boards in series with each other.

[0134] E-2: Phenomenon B The requirements for printed circuit boards are becoming more diverse. For example, there are situations where printed circuit boards of various lengths are required. Manufacturing individual printed circuit boards of various lengths to meet each individual requirement is practically difficult from the standpoint of manufacturing costs, for example. Considering these circumstances, one aspect of this disclosure (Aspect B) aims to easily realize printed circuit structures of various lengths.

[0135] A wiring structure according to one aspect of the present disclosure (Aspect B1) comprises a flexible plate-shaped base material and N (N is a natural number of 2 or more) wiring boards, each containing a plurality of wirings arranged side by side on the base material, connected in series with respect to each of the plurality of wiring boards, wherein each of the plurality of wirings is electrically connected between them, and the length of each of the N wiring boards is 10 mm or more and 6000 mm or less. In the above aspect, the wiring structure is formed by connecting N wiring boards, each with a length of 10 mm or more and 6000 mm or less. Therefore, wiring structures of various lengths can be easily realized. Since the total length of each wiring board is 10 mm or more, it is easy for workers to hold or carry each wiring board. Also, since the total length of each wiring board is 6000 mm or less, it is easy for two or fewer workers to hold the wiring board with both hands.

[0136] In a specific example of Embodiment B1 (Embodiment B2), the width of each of the plurality of wiring boards is 5 mm or more and 550 mm or less. In the above embodiment, since the width of each wiring board is 5 mm or more and 550 mm or less, it is easy for the worker to hold or transport each wiring board.

[0137] In a specific example of Embodiment B1 or Embodiment B2 (Embodiment B3), the number N of the wiring boards is 3 or more and 200 or less. In the above embodiments, the wiring structure is formed by connecting 3 or more and 200 or less wiring boards, which are composed separately from each other, in series. Therefore, it is easier to handle compared to a single wiring board formed in a very long length. For example, it is possible to easily transport or store the individual wiring boards in a separated state. In addition, since the need to wind them onto a core material during transport or storage is reduced, the possibility of each wiring board developing a curl is reduced.

[0138] E-3: Aspect C The requirements for printed circuit boards are becoming more diverse. For example, it is conceivable that printed circuit boards may be required to have a variety of functions. Conventional single printed circuit boards may not be able to adequately meet these diverse functional requirements. Taking these circumstances into consideration, one aspect of this disclosure aims to provide a wiring structure that can meet diverse requirements.

[0139] A wiring structure according to one aspect of the present disclosure (Aspect C1) comprises a flexible plate-shaped base material and N (N is a natural number of 2 or more) wiring boards, each containing a plurality of wirings arranged side by side on the base material, connected in series with respect to each of the plurality of wiring boards, wherein the configuration of the first wiring board and the second wiring board differ among the N wiring boards. In this aspect, N wiring boards, including the first and second wiring boards with different configurations, are connected to each other. Therefore, the configuration of the wiring structure is diversified compared to a configuration in which the configurations of the N wiring boards constituting the wiring structure are common. In other words, it is possible to provide a wiring structure that can meet diverse requirements.

[0140] In a specific example of embodiment C1 (embodiment C2), the first wiring board has a planar shape in which one end is branched into multiple parts, and no branching is formed on the second wiring board. According to the above embodiment, the planar shape of the wiring structure can be diversified compared to a configuration in which no branching is formed on any of the N wiring boards.

[0141] In a specific example of embodiment C1 (embodiment C3), the first wiring board has low-strength portions formed along the direction in which the plurality of wirings extend, where the mechanical strength is lower than that of other parts, and the second wiring board does not have such low-strength portions. According to the above embodiment, the planar shape of the wiring structure can be diversified by dividing the first wiring board along the low-strength portions.

[0142] In a specific example of embodiment C1 (embodiment C4), the first wiring board has a plurality of slits arranged in parallel along the direction in which the plurality of wirings extend, while the second wiring board does not have the plurality of slits formed thereon. According to the above embodiment, the planar shape of the wiring structure can be diversified by deforming the first wiring board using the plurality of slits.

[0143] In a specific example of embodiment C1 (embodiment C5), the planar shape of the first wiring board includes one or more bends, and the planar shape of the second wiring is linear and does not include the one or more bends. According to the above embodiment, the planar shape of the wiring structure can be diversified.

[0144] In a specific example of embodiment C1 (embodiment C6), the plurality of wirings on the first wiring board include one or more first wirings and one or more second wirings having a different wiring width from the one or more first wirings, and the plurality of wirings on the second wiring board have the same wiring width. According to the above embodiment, different powers can be transmitted in parallel using one or more first wirings and one or more second wirings.

[0145] In a specific example of Embodiment C1 (Embodiment C7), the first wiring board further includes one or more electronic components installed on the substrate, while the second wiring board does not include the one or more electronic components. According to the above embodiments, it is possible to mount various functions using electronic components onto the wiring structure.

[0146] In a specific example of embodiment C1 (embodiment C8), the first wiring board includes an expandable / contractable portion, while the second wiring board does not include the expandable / contractable portion. According to the above embodiment, by expanding or contracting the expandable / contractable portion of the first wiring board, it is possible to accommodate a variety of shapes of the installation surface on which the wiring structure is installed.

[0147] In a specific example of Embodiment C1 (Embodiment C9), the first wiring board further includes a protective member that covers a part of the substrate, while the second wiring board does not include the protective member. According to the above embodiments, for example, damage to the substrate caused by collision with an external element can be suppressed by the protective member.

[0148] In a specific example of Embodiment C1 (Embodiment C10), the base material in each of the N wiring boards includes a lamination of a first layer and a second layer, the plurality of wirings are installed between the first layer and the second layer, in the first wiring board, a connection terminal corresponding to each of the plurality of wirings is installed on a terminal portion of the second layer that protrudes in a first direction along the plurality of wirings in a plan view from the first layer, and a connection terminal corresponding to each of the plurality of wirings is installed on a terminal portion of the first layer that protrudes in a second direction opposite to the first direction in a plan view from the second layer, in the second wiring board, and a connection terminal corresponding to each of the plurality of wirings is installed on a terminal portion of the second layer that protrudes in a first direction from the first layer in a plan view from the second layer. According to the above embodiment, it is possible to connect multiple wiring boards in various ways.

[0149] A "plate-like" shape is a three-dimensional shape in which the thickness is sufficiently small compared to the dimensions in the in-plane direction (e.g., overall length or width). For example, expressions such as "layered," "membrane (thin film)," "film-like," and "sheet-like" are all included in the concept of "plate-like."

[0150] "Parallel installation" means being installed in a manner that is adjacent to one another. Typically, "parallel installation" refers to a state where multiple wires are placed side by side, spaced apart from each other, and running in essentially the same direction. However, it is not limited to configurations where multiple wires are parallel to each other; the concept of "parallel installation" also includes cases where two of the multiple wires are angled relative to each other. Furthermore, the spacing between each wire does not need to be constant.

[0151] "Flexibility" refers to the property of being deformable by external forces. Specifically, a typical example of "flexibility" is the property of being able to be elastically deformed by external forces without causing breakage or plastic deformation. The conditions of deformation that "flexibility" refers to are arbitrary and include any deformation such as bending or deflection. For example, expressions such as "flexibility," "elastic deformable," or "elastically deformable" are encompassed within the concept of "flexibility."

[0152] "Series connection" means that multiple elements are connected electrically or mechanically in a continuous manner in one direction. A structure in which multiple wiring boards are connected in a line, or a structure in which multiple wiring boards are connected continuously in one direction, is included in the definition of "a structure in which multiple wiring boards are connected to each other in series."

[0153] "The length of the wiring board" is the dimension between the ends of the wiring board in the direction in which multiple wires extend. On the other hand, "the width of the wiring board" is the dimension of the wiring board in the direction in which multiple wires are arranged side by side. [Explanation of Symbols]

[0154] 100...Wiring structure, 10, 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10h, 10i, 10_1, 10_2, 10_3, 10_n1, 10_n2...Wiring board, 20...Base material, 21...First layer, 22...Second layer, 23...Bonding material, 241...Foundation part, 242...Branching part, 243...Connecting pin, 244...End connector, 25...Low-strength part, 251...Separated part, 26...Slit, 261...Deformed part, 271 272,273...parts, 274,275...bent parts, 28...extendable parts, 281...bellows parts, 30...wiring, 31a,31b...connection terminals, 35...first wiring, 36...second wiring, 40...connector, 41...housing part, 41a,41b...opening, 42...conductive material, 43a,43b...holding body, 45...support part, 46a,46b...connection terminals, 47...contact part, 48...anisotropic conductive film, 49...holding member, 51...electronic component, 52...protective member.

Claims

1. A flexible plate-shaped base material, Multiple wirings arranged side by side on the substrate and A wiring structure comprising a plurality of wiring boards, each containing a plurality of wirings, connected to each other such that each of the plurality of wirings is electrically connected between the plurality of wiring boards, Of the plurality of wiring boards, the configuration of the first wiring board and the configuration of the second wiring board adjacent to the first wiring board are different. Of the aforementioned plurality of wiring boards, the configuration of the second wiring board and the configuration of the third wiring board adjacent to the second wiring board are different. The set of the first wiring board and the second wiring board, Each of the set of the second wiring board and the third wiring board is, The substrate and the plurality of wirings extend linearly in a plan view on a wiring board, A planar wiring board with one end branching into multiple parts, A wiring board having multiple slits arranged in parallel along the direction in which the multiple wirings extend, A wiring board with connecting pins installed at one end, A wiring board in which a portion of the substrate is covered with a protective member These are two wiring boards selected from: The device further comprises a connector that connects the first wiring board and the second wiring board. wiring structure.

2. The aforementioned connector is Includes a plurality of conductive members that electrically connect the plurality of wirings on the first wiring board and the plurality of wirings on the second wiring board. Wiring structure according to claim 1.

3. The ratio of the connection resistance, calculated by summing the electrical resistances at the joints of two adjacent wiring boards among the plurality of wiring boards for the entire wiring structure, to the total resistance between both ends of the wiring structure is 60.417% or less. Wiring structure according to claim 1.

4. The number of the aforementioned wiring boards is 10 or more. Wiring structure according to claim 1.

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