Connection wiring board

Abstract

To provide a connection wiring board that can achieve excellent durability against bending or stretching and connection reliability.SOLUTION: A connection wiring board includes a flexible or stretchable resin substrate 2, a plurality of stretchable wiring layers 3 arranged side by side on at least one surface of the resin substrate 2, a plurality of first electrode layers 4a arranged side by side on one end of at least one surface of the resin substrate 2, and a plurality of second electrode layers 4b arranged side by side on the other end of at least one surface of the resin substrate 2, and the wiring layers 3 are formed from a fluid metal material in which metal particles are dispersed in liquid metal, the first electrode layers 4a are electrically connected to one end of the wiring layers 3, and the second electrode layers 4b are electrically connected to the other end of the wiring layers 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wiring board for connection. [Background technology]

[0002] For example, flexible printed circuit boards (FPCs) are used to connect electronic devices such as display devices and wearable devices to external drive boards. As electronic devices become smaller and lighter, connections are being made with FPCs in a folded state.

[0003] However, in order to fold and store an FPC in a small housing, the FPC must be bent repeatedly and continuously with a small radius of curvature. Therefore, FPCs are required to have stricter bending performance to prevent breakage due to folding. Furthermore, efforts are being made to impart flexibility to the FPC substrate and to optimize the orientation and surface roughness of the copper foil typically used to withstand excessive folding. (See, for example, Patent Document 1 below.) [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-143321 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when copper foil is used for FPC wiring, excessive bending or repeated folding can cause cracks in the copper foil. In this case, the wiring breaks, making it difficult to maintain electrical connections. Furthermore, to make FPCs not only flexible but also stretchable, the substrate and wiring must be stretchable.

[0006] The present invention has been proposed in view of the above-mentioned conventional circumstances, and has an object to provide a wiring board for connection that is capable of achieving excellent durability against bending or stretching and connection reliability. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides the following means. [1] A flexible or stretchable resin substrate; a plurality of stretchable wiring layers arranged side by side on at least one surface of the resin substrate; a plurality of first electrode layers arranged side by side on one end side of at least one surface of the resin substrate; a plurality of second electrode layers provided side by side on the other end side of at least one surface of the resin substrate; the wiring layer is formed of a fluid metal material in which metal particles are dispersed in a liquid metal; the first electrode layer is electrically connected to one end of the wiring layer; The second electrode layer is electrically connected to the other end of the wiring layer. [2] The connection wiring board according to [1], wherein the wiring layer is disposed in a state of being embedded in the resin substrate. [3] The connection wiring board according to [1], further comprising a flexible or stretchable resin layer covering the surface of the resin substrate on which the plurality of wiring layers are provided. [4] A plurality of stretchable upper wiring layers arranged side by side on the surface of the resin layer; a plurality of third electrode layers arranged side by side on one end side of the resin layer; a plurality of fourth electrode layers provided side by side on the other end side of the resin layer, the upper wiring layer is formed of a fluid metal material in which metal particles are dispersed in a liquid metal, the third electrode layer is electrically connected to one end of the upper wiring layer and is electrically connected to the first electrode layer; The connection wiring board described in [3], characterized in that the fourth electrode layer is electrically connected to the other end side of the upper wiring layer and is also electrically connected to the second electrode layer. [5] The third electrode layer is electrically connected to the first electrode layer via a first end electrode provided along an edge portion of the resin layer, The connection wiring board described in [4], characterized in that the fourth electrode layer is electrically connected to the second electrode layer via a second end electrode provided along the edge portion of the resin layer. [6] The third electrode layer is electrically connected to the first electrode layer via a first through electrode that penetrates the resin layer; The connection wiring board described in [4], characterized in that the fourth electrode layer is electrically connected to the second electrode layer via a second through electrode that penetrates the resin layer. [7] The wiring board for connection according to [4], wherein the upper wiring layer is disposed in a state of being embedded in the resin layer. [8] The connection wiring board according to [4], characterized in that it comprises a flexible or stretchable resin layer covering the surface of the resin substrate on which the plurality of upper wiring layers are provided. [9] The wiring layer has one end side and the other end side electrically connected to the first electrode layer and the second electrode layer via a connection portion, The connection wiring board described in [1] is characterized in that the connection portion is composed of at least two or more laminated films including a first metal film that is easily alloyed with the liquid metal on the wiring layer side and a second metal film that is difficult to alloy with the liquid metal on the electrode layer side.

[10] The wiring board for connection according to [1], wherein the wiring layer has a layer structure in which the fluidity of the fluid metal material is lower on the lower layer side than on the upper layer side.

[11] The upper wiring layer has one end side and the other end side electrically connected to the third electrode layer and the fourth electrode layer via a connection portion, The connection wiring board described in [4] is characterized in that the connection portion is composed of a laminated film of at least two layers including a first metal film that is easily alloyed with the liquid metal on the upper wiring layer side, and a second metal film that is difficult to alloy with the liquid metal on the third electrode layer and fourth electrode layer side.

[12] The wiring board for connection according to [4], wherein the upper wiring layer has a layer structure in which the fluidity of the fluid metal material is lower on the lower layer side than on the upper layer side. [Effects of the Invention]

[0008] As described above, according to the present invention, a wiring board for connection is provided which is capable of achieving excellent durability against bending or stretching and connection reliability. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a plan view showing a configuration of a connection wiring board according to a first embodiment of the present invention. [Figure 2] 2 is a cross-sectional view of the connection wiring board taken along line AA shown in FIG. [Figure 3] 2 is a cross-sectional view of the connection wiring board taken along line BB shown in FIG. [Figure 4] FIG. 10 is a plan view showing the configuration of a connection wiring board according to a second embodiment of the present invention. [Figure 5] 5 is a cross-sectional view of the connection wiring board taken along line AA shown in FIG. 4. [Figure 6] 5 is a cross-sectional view of the connection wiring board taken along line BB shown in FIG. 4. [Figure 7] 1. FIG. 4 is a cross-sectional view of a wiring board for connection according to a third embodiment of the present invention, taken along line AA in FIG. [Figure 8] 8 is a cross-sectional view of the connection wiring board shown in FIG. 7, taken along line BB in FIG. [Figure 9] FIG. 10 is a plan view showing the configuration of a connection wiring board according to a fourth embodiment of the present invention. [Figure 10]10 is a cross-sectional view of the connection wiring board taken along line CC shown in FIG. 9. [Figure 11] 10 is a cross-sectional view of the connection wiring board taken along line DD shown in FIG. 9. [Figure 12] 10 is a cross-sectional view of the connecting wiring board taken along line EE shown in FIG. 9. FIG. [Figure 13] 10 is a plan view showing the configuration of a first-layer wiring board that constitutes the connection wiring board shown in FIG. 9. FIG. [Figure 14] 10 is a plan view showing the configuration of a second-layer wiring board that constitutes the connection wiring board shown in FIG. 9. FIG. [Figure 15] 10 is a cross-sectional view of the connection wiring board according to the fifth embodiment of the present invention, taken along line DD in FIG. 9. FIG. [Figure 16] 16 is a cross-sectional view of the connection wiring board shown in FIG. 15, taken along line EE in FIG. 9. FIG. [Figure 17] 1. FIG. 4 is a cross-sectional view showing another connection structure between a wiring layer and an electrode layer, corresponding to the line BB shown in FIG. [Figure 18] 1. FIG. 4 is a cross-sectional view showing another connection structure between a wiring layer and an electrode layer, corresponding to the line BB shown in FIG. [Figure 19] 1. FIG. 4 is a cross-sectional view showing another connection structure between a wiring layer and an electrode layer, corresponding to the line BB shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, characteristic portions may be enlarged for convenience in order to make the features easier to understand, and the dimensional ratios of each component may not be the same as in reality. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not necessarily limited to them, and can be implemented with appropriate changes within the scope of the present invention.

[0011] In the drawings shown below, an XYZ Cartesian coordinate system is set, with the X-axis direction representing a first direction X within the plane of the connection wiring board, the Y-axis direction representing a second direction Y perpendicular to the first direction X within the plane of the connection wiring board, and the Z-axis direction representing a third direction Z perpendicular to the plane of the connection wiring board.

[0012] (First embodiment) First, as a first embodiment of the present invention, the configuration of a connection wiring board 1A shown in, for example, FIGS. 1 to 3 will be described.

[0013] Fig. 1 is a plan view showing the configuration of the connection wiring board 1A. Fig. 2 is a cross-sectional view of the connection wiring board 1A taken along line AA in Fig. 1. Fig. 3 is a cross-sectional view of the connection wiring board 1A taken along line BB in Fig. 1.

[0014] As shown in Figures 1, 2 and 3, the connection wiring board 1A of this embodiment comprises a bendable or stretchable resin substrate 2, a plurality of stretchable wiring layers 3 arranged side by side on one side (surface) of the resin substrate 2, a plurality of first electrode layers 4a arranged side by side on one end side of the one side (surface) of the resin substrate 2, a plurality of second electrode layers 4b arranged side by side on the other end side of the one side (surface) of the resin substrate 2, and a bendable or stretchable resin layer 5 covering the side (surface) of the resin substrate 2 on which the plurality of wiring layers 3 are arranged.

[0015] The resin substrate 2 is a film substrate made of a flexible or stretchable resin (plastic). In this embodiment, the resin substrate 2 has a long rectangular flat plate shape. The shape and size (length and width) of the resin substrate 2 are not particularly limited and can be changed as appropriate.

[0016] For example, polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polycarbonate (PC), nanocellulose, etc. can be used for the flexible resin substrate 2. Among these, it is preferable to use PI, which has excellent heat resistance and chemical resistance.

[0017] On the other hand, for example, a stretchable resin material such as rubber or elastomer can be used for the stretchable resin substrate 2. Also, for the stretchable resin substrate 2, an acrylic resin, which has excellent transparency, weather resistance, and heat resistance, and has excellent conformability to uneven surfaces and excellent adhesive strength and holding power for curved surfaces, can be used. Furthermore, for the stretchable resin substrate 2, not only the above-mentioned acrylic resins but also, for example, silicone resins, styrene butadiene resins, etc. can be used.

[0018] The multiple wiring layers 3 extend on the surface of the resin substrate 2 in the length direction of the resin substrate 2 and are arranged side by side at regular intervals in the width direction of the resin substrate 2. The width, intervals, number, etc. of the wiring layers 3 are not particularly limited and can be changed as appropriate.

[0019] The wiring layer 3 is formed of, for example, a fluid metal material in which metal particles are dispersed in a liquid metal. The liquid metal may be, for example, a eutectic alloy containing gallium (Ga) and indium (In), or a eutectic alloy containing Ga, In, and tin (Sn). The melting point can be changed by adjusting the amount of In and Sn added to Ga as the main component.

[0020] Metal particles can be, for example, nickel (Ni), Au, Ag, Cu, or Si. The liquid metals mentioned above have very strong atomic forces, resulting in high surface energy and very poor wettability. Therefore, adding the above-mentioned metal particles can improve wettability.

[0021] For example, by mixing 1 to 20 mass % of Ni particles with an average particle size of 1 to 50 μm into a liquid metal containing gallium (Ga) and indium (In), a paste is formed, which makes it possible to form the wiring layer 3 by printing.

[0022] The plurality of first electrode layers 4a are located at one end side in the length direction of the resin substrate 2, and are arranged side by side at regular intervals in the width direction of the resin substrate 2, corresponding to each of the plurality of wiring layers 3. On the other hand, the plurality of second electrode layers 4b are located at the other end side in the length direction of the resin substrate 2, and are arranged side by side at regular intervals in the width direction of the resin substrate 2, corresponding to each of the plurality of wiring layers 3.

[0023] The first electrode layer 4a and the second electrode layer 4b can be made of, for example, a metal such as titanium (Ti), chromium (Cr), aluminum (Al), molybdenum (Mo), gold (Au), silver (Ag), copper (Cu), or an alloy thereof, or a conductive film in which two or more of these metals are stacked.

[0024] Furthermore, each first electrode layer 4a is electrically connected to one end of each wiring layer 3. That is, one end of each wiring layer 3 is arranged to extend onto each first electrode layer 4a, and is thereby in contact with one end of each first electrode layer 4a.

[0025] On the other hand, each second electrode layer 4b is electrically connected to the other end of each wiring layer 3. That is, the other end of each wiring layer 3 is arranged to extend onto each second electrode layer 4b, and is thereby in contact with one end of each second electrode layer 4b.

[0026] The resin layer 5 is provided on one surface (upper surface) of the resin substrate 2 so as to cover the entire surface of the multiple wiring layers 3, including the connection portions between each wiring layer 3 and each first electrode layer 4a and each second electrode layer 4b.

[0027] On the other hand, the other end sides of the plurality of first electrode layers 4a and the other end sides of the plurality of second electrode layers 4b are provided as terminal portions for external connection, exposed outside the resin layer 5 from both ends of the resin substrate 2.

[0028] The resin layer 5 can be formed by bonding a resin substrate having the same flexibility or stretchability as the above-mentioned resin substrate 2, or by stacking the resin layer 5 on top of the resin substrate 2.

[0029] In the connection wiring board 1A of this embodiment having the above-described configuration, the plurality of wiring layers 3 are provided so as to be able to expand and contract in accordance with the bending or expansion of the resin substrate 2 and resin layer 5. That is, since the plurality of wiring layers 3 have fluidity due to the fluid metal material described above, they can expand and contract in accordance with the bending or expansion of the resin substrate 2 and resin layer 5 without breaking.

[0030] Furthermore, the connection wiring board 1A of this embodiment can reduce changes in electrical resistance due to deformation of the wiring layer 3. Furthermore, by covering the wiring layer 3 provided on the surface of the resin substrate 2 with the resin layer 5, it is possible to prevent the occurrence of short circuits due to scattering of the fluid metal material, etc., while maintaining the shape of each wiring layer 3.

[0031] Therefore, in the connection wiring board 1A of this embodiment, even if the resin substrate 2 is excessively bent or stretched, breaks or cracks do not occur in the wiring layer 3. Furthermore, it is possible to impart self-repairing properties to the wiring layer 3. Furthermore, it is resistant to bending and folding, and is capable of maintaining electrical connection for a long period of time while maintaining flexibility.

[0032] As described above, the connection wiring board 1A of this embodiment can provide excellent durability against bending or stretching, and connection reliability.

[0033] (Second embodiment) Next, as a second embodiment of the present invention, a connection wiring board 1B shown in, for example, FIGS. 4 to 6 will be described.

[0034] Fig. 4 is a plan view showing the configuration of the connection wiring board 1B. Fig. 5 is a cross-sectional view of the connection wiring board 1B taken along line AA in Fig. 4. Fig. 6 is a cross-sectional view of the connection wiring board 1B taken along line BB in Fig. 4. In the following description, the same parts as those in the connection wiring board 1A will not be described and will be denoted by the same reference numerals in the drawings.

[0035] As shown in FIGS. 4, 5 and 6, the connection wiring board 1B of this embodiment has basically the same configuration as the connection wiring board 1A, except for the following configuration.

[0036] Specifically, in this connection wiring board 1B, the multiple wiring layers 3 are arranged in a state where they are embedded in multiple grooves 6 formed in the resin substrate 2. Specifically, each wiring layer 3 can be formed by filling each groove 6 with the above-mentioned fluid metal material using a dispenser or the like.

[0037] By being embedded in each groove 6, each wiring layer 3 can maintain its shape in accordance with the shape of the groove 6 while retaining fluidity.

[0038] Furthermore, one end of each wiring layer 3 faces the first electrode layer 4a and is electrically connected to this first electrode layer 4a. That is, the surface of each wiring layer 3 facing the first electrode layer 4a is in contact with the first electrode layer 4a. Similarly, the other end of each wiring layer 3 faces the second electrode layer 4b and is electrically connected to this second electrode layer 4b. That is, the surface of each wiring layer 3 facing the second electrode layer 4b is in contact with the second electrode layer 4b.

[0039] In the connection wiring board 1B of this embodiment having the above-described configuration, the plurality of wiring layers 3 are provided so as to be able to expand and contract in accordance with the bending or expansion of the resin substrate 2 and resin layer 5. That is, since the plurality of wiring layers 3 have fluidity due to the fluid metal material described above, they can expand and contract in accordance with the bending or expansion of the resin substrate 2 and resin layer 5 without breaking.

[0040] Furthermore, the connection wiring board 1A of this embodiment can reduce changes in electrical resistance due to deformation of the wiring layer 3. Furthermore, by covering the wiring layer 3 embedded in the groove portion 6 with the resin layer 5, it is possible to prevent the occurrence of short circuits due to scattering of the fluid metal material, etc., while maintaining the shape of each wiring layer 3.

[0041] Therefore, in the connection wiring board 1B of this embodiment, even if the resin substrate 2 is excessively bent or stretched, breaks or cracks do not occur in the wiring layer 3. Furthermore, it is possible to impart self-repairing properties to the wiring layer 3. Furthermore, it is resistant to bending and folding, and is capable of maintaining electrical connection for a long period of time while maintaining flexibility.

[0042] As described above, the connection wiring board 1B of this embodiment can provide excellent durability against bending or stretching and connection reliability.

[0043] (Third embodiment) Next, as a third embodiment of the present invention, a connection wiring board 1C shown in, for example, FIGS. 7 and 8 will be described.

[0044] Fig. 7 is a cross-sectional view of the connection wiring board 1C corresponding to the line segment AA shown in Fig. 1. Fig. 8 is a cross-sectional view of the connection wiring board 1C corresponding to the line segment BB shown in Fig. 1. In the following description, the same parts as those in the connection wiring board 1A will not be described and will be denoted by the same reference numerals in the drawings.

[0045] As shown in FIGS. 7 and 8, the connection wiring board 1C of this embodiment has basically the same configuration as the first embodiment except for the following configuration.

[0046] Specifically, this connection wiring board 1C has a configuration in which a plurality of wiring layers 3 are provided on both sides of a resin substrate 2. That is, this connection wiring board 1C includes a plurality of stretchable wiring layers 3 provided side by side on one surface (front surface) side and the other surface (rear surface) side of the resin substrate 2, a plurality of first electrode layers 4a provided side by side on one end side of the one surface (front surface) side and the other surface (rear surface) side of the resin substrate 2, a plurality of second electrode layers 4b provided side by side on the other end side of the one surface (front surface) side and the other surface (rear surface) side of the resin substrate 2, and a bendable or stretchable resin layer 5 covering the one surface (front surface) side on which the plurality of wiring layers 3 are provided and the other surface (rear surface) side of the resin substrate 2.

[0047] Furthermore, in the connection wiring board 1C of this embodiment, similar to the above-mentioned connection wiring board 1A, multiple wiring layers 3 may be arranged on the surface of the resin substrate 2, or similar to the above-mentioned connection wiring board 1B, the multiple wiring layers 3 may be arranged in a state embedded in multiple groove portions 6 formed in the resin substrate 2.

[0048] Furthermore, in the connection wiring board 1C of this embodiment, the wiring layer 3 provided on one surface (front surface) and the wiring layer 3 provided on the other surface (back surface) may be electrically connected via a through electrode (not shown) provided through the resin substrate 2.

[0049] In this configuration, it is possible to provide the first electrode layer 4a and the second electrode layer 4b on only one of the surfaces (front surface) and the other surface (rear surface).

[0050] Furthermore, in the connection wiring board 1C of this embodiment, the first and second electrode layers 4a, 4b provided on one surface (front surface) and the first and second electrode layers 4a, 4b provided on the other surface (back surface) may be electrically connected via an end electrode (not shown) provided along the edge of the resin substrate 2 or a through electrode (not shown) provided through the resin substrate 2.

[0051] In the connection wiring board 1C of this embodiment having the above-described configuration, the plurality of wiring layers 3 are provided on both sides of the resin substrate 2 so as to be able to expand and contract in accordance with the bending or expansion of the resin substrate 2 and resin layer 5. That is, since the plurality of wiring layers 3 have fluidity due to the fluid metal material described above, they can expand and contract in accordance with the bending or expansion of the resin substrate 2 and resin layer 5 without breaking.

[0052] Furthermore, the connection wiring board 1C of this embodiment can reduce changes in electrical resistance due to deformation of the wiring layer 3. Furthermore, while maintaining the shape of each wiring layer 3, it is possible to prevent short circuits and the like caused by scattering of the fluid metal material and the like.

[0053] Therefore, in the connection wiring board 1C of this embodiment, even if the resin substrate 2 is excessively bent or stretched, breaks or cracks do not occur in the wiring layer 3. Furthermore, it is possible to impart self-repairing properties to the wiring layer 3. Furthermore, it is resistant to bending and folding, and is capable of maintaining electrical connection for a long period of time while maintaining flexibility.

[0054] As described above, the connection wiring board 1C of this embodiment can achieve excellent durability against bending or stretching, and connection reliability.

[0055] (Fourth embodiment) Next, as a fourth embodiment of the present invention, a connection wiring board 1D shown in, for example, FIGS. 9 to 14 will be described.

[0056] FIG. 9 is a plan view showing the configuration of the connection wiring board 1D. FIG. 10 is a cross-sectional view of the connection wiring board 1D taken along line CC in FIG. 9. FIG. 11 is a cross-sectional view of the connection wiring board 1D taken along line DD in FIG. 9. FIG. 12 is a cross-sectional view of the connection wiring board 1D taken along line EE in FIG. 9. FIG. 13 is a plan view showing the configuration of the first-layer wiring board 11 constituting the connection wiring board 1D. FIG. 14 is a plan view showing the configuration of the second-layer wiring board 12 constituting the connection wiring board 1D. In the following description, parts equivalent to those in the connection wiring board 1A will not be described again and will be denoted by the same reference numerals in the drawings.

[0057] As shown in FIGS. 9 to 14, the connection wiring board 1D of this embodiment has basically the same configuration as the connection wiring board 1A, except for the following configuration.

[0058] Specifically, this connection wiring board 1D has a configuration in which a wiring layer 3 and an upper wiring layer 3A are laminated on one surface (surface) side of a resin substrate 2. That is, in addition to the configuration of the connection wiring board 1A, this connection wiring board 1C includes a plurality of stretchable upper wiring layers 3A arranged side by side on the surface of the resin layer 5, a plurality of third electrode layers 4c arranged side by side on one end side of one surface (surface) side of the resin layer 5, a plurality of fourth electrode layers 4d arranged side by side on the other end side of the one surface (surface) side of the resin layer 5, and a bendable or stretchable resin layer 5A covering the surface (surface) side of the resin layer 5 on which the plurality of upper wiring layers 3A are arranged.

[0059] On the other hand, in the connection wiring board 1D of this embodiment, a first electrode layer 4a that is not connected to the wiring layer 3 is provided between each pair of first electrode layers 4a that are electrically connected to one end side of the wiring layer 3. Similarly, a second electrode layer 4b that is not connected to the wiring layer 3 is provided between each pair of second electrode layers 4b that are electrically connected to the other end side of the wiring layer 3.

[0060] The plurality of upper wiring layers 3A extend on the surface of the resin layer 5 in the length direction of the resin layer 5 and are arranged side by side at regular intervals in the width direction of the resin substrate 2. The plurality of upper wiring layers 3A are also arranged so as to be located between the plurality of wiring layers 3 in a plan view.

[0061] The upper wiring layer 3A is formed using the same fluid metal material as that exemplified for the wiring layer 3. The width, spacing, number, etc. of the upper wiring layer 3A are not particularly limited and can be changed as appropriate.

[0062] The plurality of third electrode layers 4c are located at one end in the length direction of the resin layer 5, and are arranged side by side at regular intervals in the width direction of the resin substrate 2, corresponding to each of the plurality of upper wiring layers 3A. Meanwhile, the plurality of fourth electrode layers 4d are located at the other end in the length direction of the resin layer 5, and are arranged side by side at regular intervals in the width direction of the resin substrate 2, corresponding to each of the plurality of upper wiring layers 3A. The third and fourth electrode layers 4c, 4d are formed using the same materials as those exemplified for the first and second electrode layers 4a, 4b.

[0063] Each third electrode layer 4c is electrically connected to one end of each upper wiring layer 3A. That is, one end of each upper wiring layer 3A is arranged to extend onto each third electrode layer 4c, and is thereby in contact with one end of each third electrode layer 4c.

[0064] Furthermore, each third electrode layer 4c is electrically connected to the first electrode layer 4a via a first end electrode 7a provided along the edge portion on one end side of the resin layer 5. That is, a plurality of first end electrodes 7a are provided side by side in the width direction of the resin layer 5 along the edge portion on one end side of the resin layer 5 so as to electrically connect the other end side of the third electrode layer 4c and one end side of the first electrode layer 4a that is not connected to the wiring layer 3.

[0065] On the other hand, each second electrode layer 4b is electrically connected to the other end of each upper wiring layer 3A. That is, the other end of each upper wiring layer 3A is arranged to extend onto each fourth electrode layer 4d, and is thereby in contact with one end of each fourth electrode layer 4d.

[0066] Each fourth electrode layer 4d is electrically connected to the second electrode layer 4b via a second end electrode 7b provided along the edge portion on the other end side of the resin layer 5. That is, a plurality of second end electrodes 7b are provided side by side in the width direction of the resin layer 5 along the edge portion on one end side of the resin layer 5 so as to electrically connect the other end side of the fourth electrode layer 4d and one end side of the second electrode layer 4b that is not connected to the wiring layer 3.

[0067] The resin layer 5A is provided on one surface (upper surface) of the resin layer 5 so as to cover the entire surface of the multiple upper wiring layers 3A, including the connection portions between each upper wiring layer 3A and each third electrode layer 4c and each fourth electrode layer 4d.

[0068] On the other hand, the other end sides of the plurality of first electrode layers 4a and the other end sides of the plurality of second electrode layers 4b are provided as terminal portions for external connection in a state of being exposed outside the resin layer 5A.

[0069] The resin layer 5A can be formed by bonding a resin substrate having the same flexibility or stretchability as the above-mentioned resin substrate 2, or by stacking the resin layer 5 on top of the resin substrate 2.

[0070] As a result, the connection wiring board 1D of this embodiment has a structure in which a first layer wiring board 11 composed of a resin substrate 2, a wiring layer 3, and first and second electrode layers 4a, 4b, and a second layer wiring board 12 composed of an interlayer resin layer 5, an upper wiring layer 3A, and third and fourth electrode layers 4c, 4d are stacked in this order, with the top layer covered by a resin layer 5A.

[0071] Furthermore, in the connection wiring board 1D of this embodiment, the above-mentioned wiring layer 3 and upper wiring layer 3A may not only be configured to be arranged on the surfaces of the resin substrate 2 and resin layer 5, but may also be configured to be arranged in a state where they are embedded in multiple grooves (not shown) formed in the resin substrate 2 and resin layer 5.

[0072] In the connection wiring board 1D of this embodiment having the above-mentioned configuration, the multiple wiring layers 3 and upper wiring layer 3A stacked on top of each other are provided to be flexible so as to follow the bending or expansion and contraction of the resin substrate 2 and resin layers 5, 5A described above. That is, since the multiple wiring layers 3 and upper wiring layer 3A have fluidity due to the fluid metal material described above, they can be expanded and contracted so as to follow the bending or expansion and contraction of the resin substrate 2 and resin layers 5, 5A without breaking.

[0073] Furthermore, the connection wiring board 1D of this embodiment can reduce changes in electrical resistance due to deformation of the wiring layer 3 and the upper wiring layer 3A. Furthermore, it is possible to prevent short circuits and the like caused by scattering of the fluid metal material while maintaining the shapes of the wiring layer 3 and the upper wiring layer 3A.

[0074] Therefore, in the connection wiring board 1D of this embodiment, even if the resin substrate 2 is excessively bent or stretched, breaks or cracks do not occur in the wiring layer 3 and the upper wiring layer 3A. Furthermore, it is possible to impart self-repairing properties to the wiring layer 3 and the upper wiring layer 3A. Furthermore, it is resistant to bending and folding, and can maintain electrical connection for a long period of time while maintaining flexibility.

[0075] As described above, the connection wiring board 1D of this embodiment can provide excellent durability against bending or stretching and connection reliability.

[0076] (Fifth embodiment) Next, as a fifth embodiment of the present invention, a connection wiring board 1E shown in, for example, FIGS. 15 and 16 will be described.

[0077] Fig. 15 is a cross-sectional view of the connection wiring board 1E corresponding to the line segment DD shown in Fig. 9. Fig. 16 is a cross-sectional view of the connection wiring board 1E corresponding to the line segment EE shown in Fig. 9. In the following description, the same parts as those in the connection wiring boards 1A and 1D will not be described and will be denoted by the same reference numerals in the drawings.

[0078] As shown in FIGS. 15 and 16, the connection wiring board 1E of this embodiment has basically the same configuration as the connection wiring boards 1A and 1D, except for the following configuration.

[0079] That is, this connection wiring board 1E has a configuration in which, instead of the first end electrode 7a and the second end electrode 7b of the connection wiring board 1D, a first through electrode 8a and a second through electrode 8b that penetrate the resin layer 5 are provided.

[0080] Specifically, each third electrode layer 4c is electrically connected to the first electrode layer 4a via a first through electrode 8a provided to penetrate the resin layer 5. That is, a plurality of first through electrodes 8a are provided side by side in the width direction of the resin layer 5, embedded in first holes 9a that penetrate the resin layer 5, so as to electrically connect the other end side of the third electrode layer 4c and one end side of the first electrode layer 4a that is not connected to the wiring layer 3.

[0081] On the other hand, each fourth electrode layer 4d is electrically connected to the second electrode layer 4b via a second through electrode 8b provided to penetrate the resin layer 5. That is, the second end electrodes 7b are provided side by side in the width direction of the resin layer 5, embedded in second holes 9b that penetrate the resin layer 5, so as to electrically connect the other end side of the fourth electrode layer 4d to one end side of the second electrode layer 4b that is not connected to the wiring layer 3.

[0082] The first through electrode 8a and the second through electrode 8b are formed by filling the first hole 9a and the second hole 9b with a conductive material such as a metal such as titanium (Ti), chromium (Cr), aluminum (Al), molybdenum (Mo), gold (Au), silver (Ag), copper (Cu), or an alloy thereof.

[0083] In the connection wiring board 1E of this embodiment having the above-described configuration, the multiple wiring layers 3 and upper wiring layer 3A stacked on top of each other are provided to be flexible so as to follow the bending or expansion and contraction of the resin substrate 2 and resin layers 5, 5A described above. That is, since the multiple wiring layers 3 and upper wiring layer 3A have fluidity due to the fluid metal material described above, they can be expanded and contracted so as to follow the bending or expansion and contraction of the resin substrate 2 and resin layers 5, 5A without breaking.

[0084] Furthermore, the connection wiring board 1E of this embodiment can reduce changes in electrical resistance due to deformation of the wiring layer 3 and the upper wiring layer 3A. Furthermore, it is possible to prevent short circuits and the like caused by scattering of the fluid metal material while maintaining the shapes of the wiring layer 3 and the upper wiring layer 3A.

[0085] Therefore, in the connection wiring board 1E of this embodiment, even if the resin substrate 2 is excessively bent or stretched, breaks or cracks do not occur in the wiring layer 3 and the upper wiring layer 3A. Furthermore, it is possible to impart self-repairing properties to the wiring layer 3 and the upper wiring layer 3A. Furthermore, it is resistant to bending and folding, and can maintain electrical connection for a long period of time while maintaining flexibility.

[0086] As described above, the connection wiring board 1E of this embodiment can achieve excellent durability against bending or stretching and connection reliability.

[0087] The present invention is not necessarily limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0088] In the above-mentioned connection wiring boards 1A to 1D, it is possible to configure the wiring layer 3 and the upper wiring layer 3A to be electrically connected to the first to fourth electrode layers 4a to 4d via connection portions 10 as shown in FIG. 17, for example.

[0089] Specifically, this connection portion 10 is composed of a laminated film of at least two layers, including a first metal film 21 that is easily alloyed with liquid metal on the wiring layer 3 and upper wiring layer 3A side, and a second metal film 22 that is difficult to alloy with liquid metal on the first to fourth electrode layers 4a to 4d side.

[0090] The first metal film 21 may be made of, for example, a metal such as Au, Cu, or Al, or an alloy thereof, or a conductive film in which two or more of these metals are stacked.

[0091] The second metal film 22 may be made of, for example, a metal such as Ni, niobium (Nb), or tungsten (W), or an alloy thereof, or a conductive film in which two or more of these metals are stacked.

[0092] The first metal film 21 has higher wettability to liquid metal than the second metal film 22, and it is possible to form a good pattern while ensuring the fluidity of the fluid metal material when forming the wiring layer 3 and the upper wiring layer 3A on this first metal film 21.

[0093] On the other hand, the second metal film 22 is located between the first metal film 21 and the first to fourth electrode layers 4a to 4d, thereby making it possible to prevent the first to fourth electrode layers 4a to 4d from being alloyed with the liquid metal.

[0094] 18, the second metal film 22 may constitute at least a part of the first to fourth electrode layers 4a to 4d. For example, the first to fourth electrode layers 4a to 4d may be made of the same conductive film as the second metal film 22, so that the second metal film 22 can be formed integrally with the first to fourth electrode layers 4a to 4d.

[0095] In this configuration, too, it is possible to form a good pattern while ensuring the fluidity of the fluid metal material when forming the wiring layer 3 and the upper wiring layer 3A using the first metal film 21, and it is also possible to prevent the first to fourth electrode layers 4a to 4d from being alloyed with the liquid metal using the second metal film 22.

[0096] Therefore, in the above-mentioned connection wiring boards 1A to 1D, it is possible to maintain the electrical connection between the wiring layer 3 and the upper wiring layer 3A and the first to fourth electrode layers 4a to 4d in a stable state for a long period of time via such connection parts 10.

[0097] Furthermore, in the above-mentioned connection wiring boards 1A to 1D, it is possible to configure the wiring layer 3 and the lower layer side of the upper wiring layer 3A to have a layer structure in which the fluidity of the fluid metal material is lower than that of the upper layer side, as shown in, for example, FIG.

[0098] Specifically, the content of metal particles in the flowable metal material is greater on the lower side than on the upper side of the wiring layer 3 and the upper wiring layer 3A. That is, the content of metal particles in the flowable metal material increases continuously or stepwise from the upper side to the lower side of the wiring layer 3 and the upper wiring layer 3A, respectively.

[0099] The wiring layer 3 and the upper wiring layer 3A of this embodiment have a two-layer structure including an underlayer 31 and a top layer 32 that differ in the content of metal particles.

[0100] The content of metal particles in the underlayer 31 is preferably 5 to 20 mass %. On the other hand, the content of metal particles in the top layer 32 is preferably 0 to 5 mass %, which is lower than that in the underlayer 31. The average particle size of the metal particles is preferably 0.1 to 10 μm.

[0101] The underlayer 31 has a higher content of metal particles than the top layer 32, and is a layer with low fluidity of the fluid metal material, i.e., a high viscosity layer, which improves the wettability of the fluid metal material when forming the wiring layer 3 and the upper wiring layer 3A, making it possible to form good patterns with high precision on the surfaces of the resin substrate 2 and the first to fourth electrode layers 4a to 4d.

[0102] On the other hand, the top layer 32 is a layer of fluid metal material having higher fluidity than the underlayer 31, i.e., a low viscosity layer, and is formed on the underlayer 31. This ensures the fluidity of the fluid metal material while allowing the wiring layer 3 and upper wiring layer 3A to expand and contract without breaking, following the expansion and contraction of the resin substrate 2 and resin layers 5, 5A. It is also possible to reduce changes in electrical resistance due to deformation of the wiring layer 3 and upper wiring layer 3A.

[0103] This means: While maintaining the shapes of the wiring layer 3 and the upper wiring layer 3A, it is possible to maintain the electrical connections between the wiring layer 3 and the upper wiring layer 3A and the first to fourth electrode layers 4a to 4d in a stable state for a long period of time.

[0104] In addition, in the above-mentioned wiring layer 3 and upper wiring layer 3A, the boundary between the base layer 31 and the top layer 32 does not necessarily need to be clear, and it is also possible to configure the wiring layer 3 and the upper wiring layer 3A to include an intermediate layer between the base layer 31 and the top layer 32 in which the content of metal particles changes continuously.

[0105] In addition, in the above-mentioned connection wiring boards 1A to 1D, it is also possible to combine a configuration in which the wiring layer 3 and the upper wiring layer 3A are electrically connected to the first to fourth electrode layers 4a to 4d via the connection portion 10 shown in Figure 17 or Figure 18, with a configuration in which the lower layer side of the wiring layer 3 and the upper wiring layer 3A has a layer structure in which the fluidity of the fluid metal material is lower than that of the upper layer side, as shown in Figure 19.

[0106] In the above embodiment, the connecting wiring boards 1A to 1D are illustrated as having the straight shape, but at least a part of the connecting wiring boards 1A to 1D may have a curved shape that is curved in-plane.Furthermore, the connecting wiring boards 1A to 1D may have a part that is branched.

[0107] Furthermore, in the above embodiment, the connecting wiring boards 1D and 1E are exemplified in which the above-mentioned first-layer wiring board 11 and second-layer wiring board 12 are laminated in this order, but it is also possible to obtain a connecting wiring board having three or more layers by repeatedly laminating third and subsequent wiring boards identical to the second-layer wiring board 12 on top of the second-layer wiring board 12, with the uppermost layer being covered by a resin layer 5A. In this embodiment, by using a fluid metal material for the above-mentioned wiring layer 3 and upper wiring layer 3A, it is possible to obtain excellent durability and connection reliability against bending or expansion and contraction, even in a multi-layer connecting wiring board. [Explanation of symbols]

[0108] DESCRIPTION OF SYMBOLS 1A to 1E...connecting wiring board 2...resin board 3...wiring layer 3A...upper wiring layer 4a...first electrode layer 4b...second electrode layer 4c...third electrode layer 4d...fourth electrode layer 5, 5A...resin layer 6...groove portion 7a...first end electrode 7b...second end electrode 8a...first through electrode 8b...second through electrode 9a...first hole portion 9b...second hole portion 10...connection portion 11...first layer wiring board 12...second layer wiring board 21...first metal film 22...second metal film 31...underlying layer 32...top layer

Claims

1. a flexible or stretchable resin substrate; a plurality of stretchable wiring layers arranged side by side on at least one surface of the resin substrate; a plurality of first electrode layers arranged side by side on one end side of at least one surface of the resin substrate; a plurality of second electrode layers provided side by side on the other end side of at least one surface of the resin substrate; the wiring layer is formed of a fluid metal material in which metal particles are dispersed in a liquid metal; the first electrode layer is electrically connected to one end of the wiring layer; The second electrode layer is electrically connected to the other end of the wiring layer.

2. 2. The connection wiring board according to claim 1, wherein the wiring layer is disposed in a state of being embedded in the resin substrate.

3. 2. The wiring board for connection according to claim 1, further comprising a flexible or stretchable resin layer covering the surface of the resin board on which the plurality of wiring layers are provided.

4. a plurality of stretchable upper wiring layers arranged side by side on the surface of the resin layer; a plurality of third electrode layers arranged side by side on one end side of the resin layer; a plurality of fourth electrode layers provided side by side on the other end side of the resin layer, the upper wiring layer is formed of a fluid metal material in which metal particles are dispersed in a liquid metal, the third electrode layer is electrically connected to one end of the upper wiring layer and is electrically connected to the first electrode layer; 4. The connection wiring board according to claim 3, wherein the fourth electrode layer is electrically connected to the other end side of the upper wiring layer and is electrically connected to the second electrode layer.

5. the third electrode layer is electrically connected to the first electrode layer via a first end electrode provided along an edge portion of the resin layer; 5. The connection wiring board according to claim 4, wherein the fourth electrode layer is electrically connected to the second electrode layer via a second end electrode provided along an edge portion of the resin layer.

6. the third electrode layer is electrically connected to the first electrode layer via a first through electrode that penetrates the resin layer; 5. The connection wiring board according to claim 4, wherein the fourth electrode layer is electrically connected to the second electrode layer via a second through electrode that penetrates the resin layer.

7. 5. The wiring board for connection according to claim 4, wherein the upper wiring layer is disposed in a state of being embedded in the resin layer.

8. 5. The wiring board for connection according to claim 4, further comprising a flexible or stretchable resin layer covering the surface of the resin board on which the plurality of upper wiring layers are provided.

9. one end side and the other end side of the wiring layer are electrically connected to the first electrode layer and the second electrode layer via connection parts, The connection wiring board according to claim 1, characterized in that the connection portion is composed of a laminated film of at least two layers, including a first metal film on the wiring layer side that is easily alloyed with the liquid metal and a second metal film on the electrode layer side that is difficult to alloy with the liquid metal.

10. 2. The wiring board for connection according to claim 1, wherein the wiring layer has a layer structure in which the fluidity of the fluid metal material is lower on the lower layer side than on the upper layer side.

11. one end side and the other end side of the upper wiring layer are electrically connected to the third electrode layer and the fourth electrode layer via connection parts, The connection wiring board according to claim 4, characterized in that the connection portion is composed of a laminated film of at least two layers, including a first metal film that is easily alloyed with the liquid metal on the upper wiring layer side, and a second metal film that is difficult to alloy with the liquid metal on the third electrode layer and fourth electrode layer side.

12. 5. The wiring board for connection according to claim 4, wherein the upper wiring layer has a layer structure in which the fluidity of the fluid metal material is lower on the lower layer side than on the upper layer side.

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