Connection circuit and manufacturing method thereof

Abstract

To provide a connection circuit and a manufacturing method thereof that can be easily produced using conductive ink, increase the degree of freedom in circuit formation, and improve noise resistance.SOLUTION: A connection circuit 40 includes a substrate 10 and a circuit 20 printed on the substrate 10 with conductive ink, with a portion of the substrate 10 folded such that at least a portion of the circuit 20 overlaps in the vertical direction when viewed from the side, and the substrate 10 is interposed between the circuits 20 in the vertical direction when viewed from the side.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a connection circuit and a method for manufacturing the same. [Background technology]

[0002] In recent years, due to the reduction in wiring space in automobiles, there is a demand for flexible printed circuit boards (FPCs) that can achieve smaller, thinner, and three-dimensional wiring harnesses and their peripheral components. In particular, there is a demand for thinner sensor modules equipped with FPCs that can detect the current of each cell in order to control the batteries installed in automobiles as they become more electrified.

[0003] To meet demands for miniaturization, thinning, and three-dimensionality, there is a demand for printed circuits that offer greater flexibility in circuit formation than FPCs and can be manufactured inexpensively. These printed circuits are formed by printing a conductive material, such as a conductive ink or conductive paste of silver or copper, onto a flexible substrate made of a thin, soft, electrically insulating resin film using a printing method such as screen printing to form a conductive layer. For example, Patent Document 1 describes the production of a substrate for a printed wiring board by printing a conductive ink with dispersed metal particles onto an insulating substrate made of a film or sheet. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-272837 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the substrate for printed wiring boards described in Patent Document 1, circuits are formed on the same layer, which limits the degree of freedom in circuit formation, making it difficult to form complex circuits such as twisted structures. Furthermore, when layers are stacked to form a multilayer structure, the design and manufacturing processes become complicated, and noise occurs between parallel circuits.

[0006] The present invention has been made in view of the problems inherent in the prior art, and an object of the present invention is to provide a connection circuit and a manufacturing method thereof that can be easily produced using conductive ink, that increases the degree of freedom in circuit formation, and that has improved noise resistance. [Means for solving the problem]

[0007] A connection circuit according to an embodiment of the present invention comprises an electrically insulating substrate and a circuit printed on the substrate with conductive ink, wherein a portion of the substrate is folded so that at least a portion of the circuit overlaps in the vertical direction when viewed from the side, and the substrate is interposed between the circuits in the vertical direction when viewed from the side.

[0008] Another aspect of the present invention relates to a method for manufacturing a connection circuit, which includes an electrically insulating substrate and a circuit printed on the substrate with conductive ink, and includes the steps of printing the circuit on the substrate with conductive ink, punching out a portion of the substrate and processing the substrate so that it has connecting portions and a plurality of divided substrates connected via the connecting portions, and bending the connecting portions to arrange the circuits printed on the plurality of divided substrates so that at least a portion of the circuits overlap in the vertical direction when viewed from the side, and so that the substrate is interposed between the circuits in the vertical direction when viewed from the side. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a connection circuit and a manufacturing method thereof that can be easily produced using conductive ink, that increases the degree of freedom in circuit formation, and that has improved noise resistance. [Brief explanation of the drawings]

[0010] [Figure 1A] FIG. 1 is a schematic diagram showing an example of a circuit printed on a substrate. [Figure 1B] 1B is a schematic diagram showing the state after the substrate shown in FIG. 1A has been punched and divided. FIG. [Figure 1C] 1C is a top view showing the connection circuit after the base material shown in FIG. 1B is folded. FIG. [Figure 2A] FIG. 1 is a schematic diagram showing an example of a circuit printed on a substrate. [Figure 2B] 2B is a schematic diagram showing the state after the base material shown in FIG. 2A has been punched and divided. FIG. [Figure 2C] 2C is a top view showing the connection circuit after the base material shown in FIG. 2B is folded. [Figure 3] 1B or 2B after being folded. FIG. [Figure 4] 4 is a side view showing the connection circuit after the base material shown in FIG. 3 has been crushed in the vertical direction. [Figure 5A] FIG. 1 is a schematic diagram showing an example of a circuit printed on a substrate. [Figure 5B] FIG. 5B is a schematic diagram showing the state after the base material shown in FIG. 5A has been punched and divided. [Figure 5C] 5C is a top view showing the connection circuit after the base material shown in FIG. 5B is folded. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] The connection circuit and the manufacturing method thereof according to the present embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios.

[0012] <Connection circuit> [First embodiment] The connection circuit 40 of this embodiment includes an electrically insulating substrate 10 and a circuit 20 printed on the substrate 10 with conductive ink. The circuit 20 is printed by applying the conductive ink in a desired shape onto the substrate 10 and then baking it. The circuit 20 includes a conductor pattern formed to extend in the longitudinal direction of the substrate 10.

[0013] Known conductive inks can be used to form the circuit 20. Conductive inks are composed of conductive fillers, binders, organic solvents, and the like, and are applied and then baked to form conductors, enabling electrical continuity. Examples of conductive fillers contained in the conductive ink include carbon components and metal components. The carbon component preferably contains at least one selected from the group consisting of carbon black, graphite, graphene, carbon nanotubes, and carbon fibers. Furthermore, the metal component preferably contains at least one selected from the group consisting of gold, silver, copper, platinum, palladium, rhodium, ruthenium, iridium, osmium, tungsten, nickel, tantalum, bismuth, lead, indium, tin, zinc, and titanium.

[0014] The method for printing the conductive ink on the substrate 10 is not particularly limited, and can be any conventionally known method such as screen printing, rotary screen printing, flexographic printing, inkjet printing, gravure printing, gravure offset printing, offset printing, etc. Screen printing is preferred because it allows for inexpensive mass production.

[0015] The substrate 10 that can be used for the circuit 20 can be an electrically insulating film, sheet, or plate. The substrate 10 is also flexible and can be folded or otherwise adapted to the location of use. The material of the substrate 10 can be at least one selected from the group consisting of polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polypropylene (PP), and polybutylene terephthalate (PBT).

[0016] In the connection circuit 40 of this embodiment, as described below, a portion of the substrate 10 is bent. In addition, in the connection circuit 40, at least a portion of the circuits 20 overlaps in the vertical direction in a plan view, and the substrate 10 is interposed between the circuits 20 in the vertical direction when viewed from the side.

[0017] The substrate 10 may have connecting portions 10D and 10E and multiple divided substrates 10A, 10B, and 10C connected via the connecting portions 10D and 10E. Specifically, a circuit 20 having multiple conductor patterns (multiple lines shown in FIG. 1A) extending linearly and parallel to each other may be formed on the surface of the substrate 10 by first pattern-printing a conductive ink on the surface of the substrate 10 using the printing method described above (step (a) described below). As shown in FIG. 1A, the portion of the circuit 20 that will be positioned on the upper side when folded in step (c) described below may be designated as circuit 20A, and the portion that will be positioned on the lower side may be designated as circuit 20C. Note that the number of conductor patterns constituting the circuit 20 (20A, 20C) is not limited and may be one or multiple. Furthermore, the shape of the conductor patterns constituting the circuit 20 (20A, 20C) is not limited and may be freely formed.

[0018] Then, a portion of the base material 10 may be punched out, and the base material 10 may be processed to have connecting portions 10D, 10E and a plurality of divided base materials 10A, 10B, 10C connected via the connecting portions 10D, 10E (step (b) described below).

[0019] 1B, the base material 10 is composed of divided base materials 10A, 10B, and 10C and connecting portions 10D and 10E. Connecting portion 10D connects divided base material 10A to divided base material 10B. Connecting portion 10E connects divided base material 10B to divided base material 10C. In other words, divided base materials 10A, 10B, and 10C are connected by connecting portions 10D and 10E.

[0020] Of the three divided base materials, divided base materials 10A and 10C each have a circuit 20 formed thereon. Specifically, divided base material 10A has a circuit 20A formed thereon, and divided base material 10C has a circuit 20C formed thereon. On the other hand, divided base material 10B and connecting portions 10D and 10E do not have a circuit 20 formed thereon.

[0021] The connecting portions 10D, 10E may be folded so that at least a portion of the circuits 20A, 20C printed on the divided base materials 10A, 10C overlap in the vertical direction in a plan view. Specifically, as shown in Fig. 3, the connecting portions 10D, 10E of the base material 10 are folded with the side on which the circuit 20 is printed facing inward and with the longitudinal direction of the base material 10 as the axis. Furthermore, as shown in Fig. 4, the base material 10 is pressed and overlapped in the vertical direction by thermoforming or the like to produce the connection circuit 40 (step (c) described below).

[0022] As shown in FIGS. 4 and 1C, in connection circuit 40, with divided substrate 10A positioned at the top, circuits 20A and 20C are vertically overlapped in a plan view. Specifically, as shown in FIG. 4, divided substrate 10A, circuit 20A, divided substrate 10C, circuit 20C, and divided substrate 10B are arranged in this order from top to bottom, and divided substrate 10C is interposed between circuits 20A and 20C in a vertical view when viewed from the side. Furthermore, as shown by the dotted line in FIG. 1C, circuits 20A and 20C may completely overlap in the vertical direction. Because circuits 20A and 20C are surrounded by substrate 10, substrate 10 functions as an insulating coating for the electric wires, resulting in an assembled electric wire in which circuits 20A and 20C are insulated and protected.

[0023] The connection circuit 40 is produced by printing the circuit 20 on a single substrate 10 using conductive ink, then folding the substrate 10 and stacking the layers. This allows for simple production with fewer manufacturing steps, despite the multilayer structure. Furthermore, the multilayer structure of the connection circuit 40 allows for greater freedom in circuit formation, making it possible to produce a thinner and lighter circuit than conventional coated wires. Furthermore, the connection circuit 40 has circuits 20A and 20C stacked one above the other with the divided substrate 10C sandwiched between them, improving noise resistance.

[0024] As described above, the connection circuit 40 of this embodiment includes an electrically insulating substrate 10 and a circuit 20 printed on the substrate 10 with conductive ink. The connection circuit 40 is formed by folding a portion of the substrate 10, so that at least a portion of the circuit 20 overlaps in the vertical direction in a plan view, and the substrate 10 is interposed between the circuits 20 in the vertical direction in a side view. Therefore, the connection circuit 40 can be easily produced using conductive ink, and a connection circuit can be provided that increases the degree of freedom in circuit formation and improves noise resistance.

[0025] <Method of manufacturing connection circuit> The method for manufacturing the connection circuit 40 of this embodiment is a method for manufacturing a connection circuit 40 that includes an electrically insulating substrate 10 and a circuit 20 printed on the substrate 10 with conductive ink.

[0026] The manufacturing method for the connection circuit 40 of this embodiment includes a step (step (a)) of printing the circuit 20 on the substrate 10 using conductive ink. The manufacturing method also includes a step (step (b)) of punching out a portion of the substrate 10 and processing the substrate 10 so that it has a connecting portion and a plurality of divided substrates connected via the connecting portion. The manufacturing method then includes a step (step (c)) of bending the connecting portion and arranging the divided substrates so that at least a portion of the circuits printed on the plurality of divided substrates overlaps in the vertical direction in a plan view. The manufacturing method also includes a step (step (c)) of arranging the circuits 20 so that the substrate 10 is interposed between them in the vertical direction when viewed from the side. Each step will be described below.

[0027] [Process (a)] Step (a) is a step of printing a circuit 20 using conductive ink on an electrically insulating substrate 10. By pattern-printing the conductive ink on the surface of the substrate 10 using the printing method described above, a circuit 20 having a plurality of conductor patterns extending linearly and parallel to one another may be formed on the substrate 10. As shown in FIG. 1A , the portion of the circuit 20 that will be positioned on the upper side when folded in step (c) is designated as circuit 20A, and the portion that will be positioned on the lower side is designated as circuit 20C.

[0028] [Step (b)] Step (b) is a step of punching out a portion of base material 10 so that base material 10 has connecting portions 10D and 10E and a plurality of divided base materials 10A, 10B, and 10C connected via connecting portions 10D and 10E.

[0029] 1B, the base material 10 is composed of divided base materials 10A, 10B, and 10C and connecting portions 10D and 10E. Connecting portion 10D connects divided base material 10A to divided base material 10B. Connecting portion 10E connects divided base material 10B to divided base material 10C. In other words, divided base materials 10A, 10B, and 10C are connected by connecting portions 10D and 10E.

[0030] Of the three divided base materials, divided base materials 10A and 10C each have a circuit 20 formed thereon. Specifically, divided base material 10A has a circuit 20A formed thereon, and divided base material 10C has a circuit 20C formed thereon. On the other hand, divided base material 10B and connecting portions 10D and 10E do not have a circuit 20 formed thereon.

[0031] The method for punching out a portion of the base material 10 is not particularly limited, and can be a conventionally known method. After punching out, as shown in Fig. 1B, the base material 10 may have punched-out portions 30 extending along the longitudinal direction thereof so as to sandwich the connecting portions 10D and 10E.

[0032] [Process (c)] Step (c) is a step of folding the connecting portions 10D and 10E to arrange the divided substrates 10A and 10C so that at least a portion of the circuits 20A and 20C printed on the divided substrates 10A and 10C overlap vertically in a plan view. Furthermore, step (c) is a step of arranging the divided substrates 10A and 10C so that the substrate 10 is interposed between the circuits 20 in the vertical direction when viewed from the side. Specifically, as shown in FIG. 3, the connecting portions 10D and 10E of the substrate 10 are folded with the side on which the circuit 20 is printed facing inward and with the longitudinal direction of the substrate 10 as the axis. That is, the divided substrate 10A, the circuit 20A, the divided substrate 10C, the circuit 20C, and the divided substrate 10B are arranged in this order from the top. The divided substrates 10A and 10C are then arranged so that at least a portion of the circuits 20A and 20C printed on the divided substrates 10A and 10C overlap vertically in a plan view. Furthermore, the divided substrate 10C is arranged so that the divided substrate 10C is interposed between the circuits 20A and 20C in the vertical direction when viewed from the side. After folding as shown in Fig. 3, the base material 10 can be flattened and stacked in the vertical direction by thermoforming or the like, as shown in Fig. 4, to produce the connection circuit 40. As shown by the dotted line in Fig. 1C, the circuits 20A and 20C may be completely stacked in the vertical direction. In this way, the circuits 20A and 20C are surrounded by the base material 10, and the base material 10 functions as an insulating coating for the wires, making it possible to form an assembled electric wire in which the circuits 20A and 20C are insulated and protected.

[0033] The manufacturing method of the connection circuit 40 is a method in which the circuit 20 is printed on a single sheet of substrate 10 using conductive ink, and then the substrate 10 is folded and layered. This means that, despite the multilayer structure, the manufacturing process is simple and requires few steps. Furthermore, the multilayer structure of the connection circuit 40 allows for greater freedom in circuit formation, making it possible to make the circuit thinner and lighter than conventional coated electric wires. Furthermore, the connection circuit 40 has circuits 20A and 20C stacked one above the other with the divided substrate 10C sandwiched between them, thereby improving noise resistance.

[0034] As described above, the manufacturing method for the connection circuit 40 of this embodiment is a method for manufacturing a connection circuit including an electrically insulating substrate and a circuit printed on the substrate with conductive ink. The manufacturing method includes a step of printing the circuit 20 on the substrate 10 with conductive ink. The manufacturing method also includes a step of punching out a portion of the substrate 10 to form the substrate 10 with connecting portions 10D and 10E and multiple divided substrates 10A, 10B, and 10C connected via the connecting portions 10D and 10E. The manufacturing method also includes a step of bending the connecting portions 10D and 10E to arrange the circuits 20A and 20C printed on the multiple divided substrates 10A and 10C so that at least a portion of the circuits 20A and 20C overlap vertically in a plan view. The manufacturing method also includes a step of arranging the circuits 20 so that the substrate 10 is interposed between the circuits 20 in a vertical direction when viewed from the side. Therefore, the method for manufacturing the connection circuit 40 allows for easy production using conductive ink, and can provide a connection circuit with increased freedom in circuit formation and improved noise resistance.

[0035] [Second embodiment] Next, a connection circuit 40 according to a second embodiment will be described with reference to FIGS. 2A to 2C. The conductive patterns constituting the circuit 20 may have a joint structure that allows a plurality of conductive patterns to be integrally connected. Specifically, as shown in FIG. 2A, by pattern-printing conductive ink on the surface of the substrate 10 using the printing method described above, a plurality of conductive patterns at both ends of the substrate 10 may be connected to a single conductive pattern in the center. The number of conductive patterns constituting the circuit 20 (20A, 20C) is not limited, and may be one or multiple. The shape of the conductive patterns constituting the circuit 20 (20A, 20C) is also not limited, and can be freely formed. The other parts are the same as those of the connection circuit 40 according to the first embodiment, and therefore description thereof will be omitted.

[0036] As shown in Fig. 2B, the substrate 10 is composed of divided substrates 10A, 10B, and 10C and connecting portions 10D and 10E. The divided substrates 10A, 10B, and 10C are connected by the connecting portions 10D and 10E. A circuit 20A is formed on the divided substrate 10A, and a circuit 20C is formed on the divided substrate 10C. On the other hand, the circuit 20 is not formed on the divided substrate 10B and the connecting portions 10D and 10E.

[0037] 2C, the connecting portions 10D, 10E may be folded so that at least a portion of the circuits 20A, 20C printed on the divided base materials 10A, 10C are vertically overlapped in a plan view. Specifically, as shown in FIG. 3, the connecting portions 10D, 10E of the base material 10 are folded with the surface on which the circuit 20 is printed facing inward and with the longitudinal direction of the base material 10 as the axis. Furthermore, as shown in FIG. 4, the base material 10 is vertically crushed and overlapped by thermoforming or the like to produce the connection circuit 40.

[0038] As shown in FIGS. 4 and 2C , in connection circuit 40, with divided substrate 10A positioned at the top, circuits 20A and 20C are vertically overlapped in a plan view. Specifically, as shown in FIG. 4 , divided substrate 10A, circuit 20A, divided substrate 10C, circuit 20C, and divided substrate 10B are arranged in this order from top to bottom, and divided substrate 10C is interposed between circuits 20A and 20C in a vertical view. Furthermore, as shown by the dotted line in FIG. 2C , circuits 20A and 20C may completely overlap in the vertical direction. Because circuits 20A and 20C are surrounded by substrate 10, substrate 10 functions as an insulating coating for the electric wires, resulting in an assembled electric wire in which circuits 20A and 20C are insulated and protected.

[0039] The connection circuit 40 is fabricated by printing the circuit 20 on a single substrate 10 using conductive ink, then folding the substrate 10 to stack layers. This allows for easy fabrication with fewer manufacturing steps despite its multilayer structure. Furthermore, the multilayer structure of the connection circuit 40 allows for greater flexibility in circuit formation, making it possible to achieve a thinner and lighter structure than conventional coated electric wires. Furthermore, the connection circuit 40 has circuits 20A and 20C stacked vertically with the divided substrate 10C sandwiched between them, improving noise resistance. Therefore, like the connection circuit 40 according to the first embodiment, the connection circuit 40 can be easily fabricated using conductive ink, providing greater flexibility in circuit formation and improved noise resistance.

[0040] [Third embodiment] Furthermore, a connection circuit 40 according to a third embodiment will be described with reference to FIGS. 5A to 5C. The conductive patterns constituting the circuit 20 may have wavy lines. As shown in FIG. 5A, from the viewpoint of noise resistance, which will be described later, it is preferable that the wavy lines of the conductor patterns of the circuits 20A and 20C have the same pitch (the distance between peaks) and amplitude. The number of conductor patterns constituting the circuit 20 (20A, 20C) is not limited, and may be one or more. The shape of the wavy lines of the conductor patterns constituting the circuit 20 (20A, 20C) is not limited, and can be freely formed. The other parts are the same as those of the connection circuit 40 according to the first embodiment, and therefore description thereof will be omitted.

[0041] As shown in Fig. 5B, the substrate 10 is composed of divided substrates 10A, 10B, and 10C and connecting portions 10D and 10E. The divided substrates 10A, 10B, and 10C are connected by the connecting portions 10D and 10E. A circuit 20A is formed on the divided substrate 10A, and a circuit 20C is formed on the divided substrate 10C. On the other hand, the circuit 20 is not formed on the divided substrate 10B and the connecting portions 10D and 10E.

[0042] 5C, the connecting portions 10D, 10E may be folded so that at least a portion of the circuits 20A, 20C printed on the divided base materials 10A, 10C are vertically overlapped in a plan view. Specifically, the connecting portions 10D, 10E of the base material 10 are folded with the printed surface of the circuit 20 facing inward and with the longitudinal direction of the circuit 20 as the axis. The base material 10 is then vertically crushed and overlapped by thermoforming or the like to produce the connection circuit 40.

[0043] 5C , in connection circuit 40, with divided base material 10A positioned at the top, circuits 20A and 20C are stacked vertically in a plan view, and in a side view, divided base material 10C is interposed between circuits 20A and 20C. In this way, since circuits 20A and 20C are surrounded by base material 10, base material 10 functions as an insulating coating for the electric wires, and an assembled electric wire is formed in which circuits 20A and 20C are insulated and protected.

[0044] On the other hand, when the conductor patterns of circuits 20A and 20C have the same pitch and amplitude of the wavy lines, it is preferable that the positions of the peaks and valleys of the two wavy lines of the conductor pattern are reversed in plan view, as shown in Figure 5C. When the conductor patterns of circuits 20A and 20C are in this state, the currents flowing through circuits 20A and 20C cancel out each other's magnetic fields, thereby improving noise resistance similar to that of a twisted pair cable. A twisted pair cable has a structure in which two electric wires are twisted together in a spiral shape and is known as a cable with high noise shielding properties.

[0045] The connection circuit 40 is fabricated by printing the circuit 20 on a single substrate 10 using conductive ink, then folding the substrate 10 to stack layers. This allows for easy fabrication with fewer manufacturing steps, despite its multilayer structure. Furthermore, the multilayer structure of the connection circuit 40 allows for greater flexibility in circuit formation, making it possible to achieve thinner and lighter designs than conventional coated wires. Furthermore, the connection circuit 40 has circuits 20A and 20C stacked one above the other, sandwiching the divided substrate 10C. By reversing the positions of the peaks and valleys of the wavy lines of the conductor pattern in a plan view, noise resistance can be improved. Therefore, like the connection circuit 40 according to the first embodiment, the connection circuit 40 can be easily fabricated using conductive ink, providing greater flexibility in circuit formation and improved noise resistance.

[0046] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment. [Explanation of symbols]

[0047] 10 Base material 10A,10B,10C split base material 10D, 10E Joint 20, 20A, 20C circuit 40 Connection circuit

Claims

1. an electrically insulating substrate; a circuit printed on the substrate with conductive ink; Equipped with A portion of the substrate is folded, and at least a portion of the circuit overlaps in a vertical direction in a plan view, A connection circuit in which, when viewed from the side, the substrate is interposed between the circuits in the up-down direction.

2. The base material has a connecting portion and a plurality of divided base materials connected via the connecting portion, The connection circuit according to claim 1 , wherein the connecting portion is bent so that at least a portion of the circuits printed on the plurality of divided base materials overlaps in the vertical direction in a plan view.

3. 3. The connection circuit according to claim 1, wherein the conductor patterns constituting the circuit have a joint structure.

4. 3. The connection circuit according to claim 1, wherein the conductor pattern constituting the circuit has wavy lines.

5. an electrically insulating substrate; a circuit printed on the substrate with conductive ink; A method for manufacturing a connection circuit comprising: printing a circuit on the substrate with the conductive ink; A step of punching out a portion of the base material so that the base material has a connecting portion and a plurality of divided base materials connected via the connecting portion; The connecting portion is folded, and the circuits printed on the divided base materials are arranged so that at least a portion of the circuits overlap in the vertical direction in a plan view. a step of arranging the substrate so that the substrate is interposed between the circuits in the vertical direction when viewed from the side; A method for manufacturing a connection circuit comprising:

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