Method for manufacturing a multi-core cable and multi-core cable

Abstract

This invention provides a method for manufacturing a multi-core cable that allows multiple wires to be connected to a connecting member simultaneously, such as when the diameters of multiple wires are not uniform. [Solution] Each of the multiple electric wires 11 and 12 includes a conductor, a covering that covers the conductor, and exposed portions E1 and E2 where the conductor is exposed when the covering is removed. The connecting member includes a substrate, and the first surface of the substrate 21 is provided with multiple terminals 23 corresponding to each of the multiple electric wires. When the substrate is placed on a horizontal surface with the first surface facing upward, the height of the tops of the exposed portions placed on the corresponding terminals is not uniform. The manufacturing method includes a placement step of placing the exposed portions and solder 30 on the multiple terminals, and a connection step of connecting the multiple terminals and the exposed portions of the multiple electric wires corresponding to the multiple terminals all at once by pressing a flexible member 40 against the exposed portions and pressing toward the substrate, while heating the conductors using a non-contact method to melt the solder and solder them.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a multi-core cable and a multi-core cable.

Background Art

[0002] Patent Document 1 discloses a multi-core cable assembly in which a plurality of cables having different diameters are connected to a connecting member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When connecting a plurality of electric wires to a substrate, a method of simultaneously pressing and heating the plurality of electric wires by a pulse heat method may be employed. However, when connecting a plurality of electric wires having different diameters or when there are irregularities or steps on the substrate, some of the electric wires and the heater tip may not be in sufficient contact, resulting in a risk of poor connection.

[0005] An object of the present disclosure is to provide a method for manufacturing a multi-core cable capable of simultaneously connecting a plurality of electric wires to a substrate even when the diameters of the plurality of electric wires are not uniform.

Means for Solving the Problems

[0006] A method for manufacturing a multi-core cable according to one embodiment of the present disclosure is a method for manufacturing a multi-core cable comprising a plurality of electric wires and a substrate, wherein each of the plurality of electric wires includes a conductor, a covering covering the conductor, and an exposed portion where the conductor is exposed when the covering is removed, and a plurality of terminals corresponding to each of the plurality of electric wires are provided on the first surface of the substrate, and when the substrate is placed on a horizontal surface with the first surface facing upward, the height of the top of the exposed portion placed on the corresponding terminal is not uniform, and the manufacturing method includes a placement step of placing the exposed portion and solder on the plurality of terminals, and a connection step of connecting the plurality of terminals and the exposed portion of the plurality of electric wires corresponding to the plurality of terminals all at once by pressing a flexible member against the exposed portion and pressing it toward the substrate, while heating the conductor by a non-contact method to melt the solder and soldering. [Effects of the Invention]

[0007] According to this disclosure, when the diameters of multiple electric wires are not uniform, etc., multiple electric wires can be connected to a connecting member simultaneously. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram of a multi-core cable according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a cross-sectional view of the cable. [Figure 3] Figure 3 is a plan view of the connection point between the electric wire and the circuit board. [Figure 4] Figure 4 shows one step in the manufacturing method of a multi-core cable according to one embodiment of the present disclosure. [Figure 5] Figure 5 shows an example of a step in the connection process in which a flexible member is used to press the exposed portion. [Figure 6] Figure 6 shows the connection process in the manufacturing method according to the first comparative example. [Figure 7] Figure 7 shows the connection process in the manufacturing method according to the second comparative example. [Figure 8]Figure 8 shows a modified configuration to which the manufacturing method of the present disclosure is applied. [Figure 9] Figure 9 shows a modified example of a configuration to which the manufacturing method of the present disclosure is applied. [Figure 10] Figure 10 shows a modified configuration to which the manufacturing method of the present disclosure is applied. [Figure 11] Figure 11 shows a modified configuration to which the manufacturing method of the present disclosure is applied. [Modes for carrying out the invention]

[0009] [Description of Embodiments in this Disclosure] First, the embodiments of this disclosure will be listed and described. (1) A method for manufacturing a multi-core cable according to one embodiment of the present disclosure is a method for manufacturing a multi-core cable comprising a plurality of electric wires and a substrate, wherein each of the plurality of electric wires includes a conductor, a covering covering the conductor, and an exposed portion where the conductor is exposed when the covering is removed, and a plurality of terminals corresponding to each of the plurality of electric wires are provided on the first surface of the substrate, and when the substrate is placed on a horizontal surface with the first surface facing upward, the height of the top of the exposed portion placed on the corresponding terminal is not uniform, and the manufacturing method includes a placement step of placing the exposed portion and solder on the plurality of terminals, and a connection step of connecting the plurality of terminals and the exposed portion of the plurality of electric wires corresponding to the plurality of terminals all at once by pressing a flexible member against the exposed portion and pressing toward the substrate, while heating the conductor by a non-contact method to melt the solder and soldering.

[0010] In pulse heating methods, which use a heater tip to apply pressure while heating, connection failures are likely to occur in the relatively lower parts of the wires being connected if the tops of the wires are not uniform in height. If a flexible material is placed between the heater tip and the wire to uniformly press the wires of different heights, the cycle time increases due to the low thermal conductivity of the flexible material. By pressing the wire with a flexible material while heating the wire using a non-contact method that does not involve the flexible material, it is possible to reliably connect wires of different heights all at once.

[0011] (2) In (1) above, the plurality of wires may include a plurality of wires having different outer diameters for their conductors. According to the above manufacturing method, wires of different diameters can be connected to the substrate all at once.

[0012] (3) In (1) above, the first surface of the substrate has a first region and a second region at different heights from the horizontal plane, and terminals are provided in each of the first region and the second region, and in the connection step, the exposed portions of the corresponding multiple electric wires may be connected collectively to the terminals provided in the first region and the terminals provided in the second region. According to the above manufacturing method, even if there are steps or inclines on the surface of the substrate on which the terminals are provided, multiple electric wires can be connected collectively.

[0013] (4) In any of (1) to (3) above, the non-contact method may be heating by hot air. Heating by hot air makes it easy to control the heating area and makes it easy to avoid damage to surrounding connecting members and wire insulation.

[0014] (5) In any one of the above (1) to (4), the heating of the exposed portion by the non-contact method heats a first portion of the electric wire that extends from the exposed portion in a first direction, and heat is conducted from the conductor of the first portion to the exposed portion. After the connection step, a cutting step of cutting the electric wire to remove the first portion may be further included. A soft member is pressed against the exposed conductor, and it is difficult to directly heat that portion. Therefore, a method of heating a first portion near the exposed conductor and causing heat conduction through the conductor to heat the target conductor portion can be adopted. In this case, the first portion directly heated tends to become high in temperature, and there is a possibility that the coating of the electric wire or the like may be damaged. Therefore, by leaving a portion that becomes a product on the side opposite to the first portion with respect to the exposed conductor and cutting the first portion after the connection step, damage to the portion that becomes a product can be avoided.

[0015] (6) A multi-core cable according to an embodiment of the present disclosure is a multi-core cable including a plurality of electric wires and a substrate. Each of the plurality of electric wires includes a conductor, a coating covering the conductor, and an exposed portion where the conductor is exposed by removing the coating. A plurality of terminals corresponding to each of the plurality of electric wires are provided on a first surface of the substrate. The terminal and the exposed portion are electrically connected by solder. When the substrate is placed on a horizontal plane with the first surface facing upward, the heights of the tops of the conductors of the plurality of electric wires connected to the corresponding terminals are not uniform. Conventionally, it has been difficult to satisfactorily connect electric wires with non-uniform heights to a substrate, but according to the present disclosure, a multi-core cable in which electric wires with non-uniform heights are satisfactorily connected to a substrate can be obtained.

[0016] (7) In the above (6), at the tips of the plurality of electric wires, the end of the exposed portion and the end of the solder may be formed on the same plane. The end of the electric wire not covered with solder is formed by cutting the electric wire after soldering. When heating the electric wire for soldering, there is a possibility that the coating of the electric wire or the like may be damaged by heat. By cutting the electric wire at the heated portion after soldering, damage to the portion that becomes a product can be avoided.

[0017] (8) In (6) or (7) above, the plurality of electric wires may include electric wires having different outer diameters of the conductors. According to this embodiment, electric wires of different diameters can be collectively connected to the substrate.

[0018] (9) In (6) or (7) above, on the first surface of the substrate, there are a first region and a second region having different heights from the horizontal plane, and the terminals may be provided in each of the first region and the second region. According to this embodiment, even when there are steps or inclinations on the surface of the substrate where the terminals are provided, a plurality of electric wires can be collectively connected.

[0019] (10) In (9) above, the first surface of the substrate may have a step.

[0020] (11) In (9) above, the first surface of the substrate may be inclined with respect to the horizontal plane.

[0021] (12) In (9) above, the first surface of the substrate may have a curved surface.

[0022] [Details of Embodiments of the Present Disclosure] Specific examples of the multi-core cable and the manufacturing method of the multi-core cable of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, and is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. Note that U, D, F, B, R, and L shown in each drawing indicate directions in the multi-core cable 1, where U is upward, D is downward, F is forward, B is backward, R is rightward, and L is leftward.

[0023] (Multi-core Cable) FIG. 1 is a schematic view of a multi-core cable 1 according to an embodiment of the present disclosure. As shown in FIG. 1, the multi-core cable 1 includes a substrate 21. Only one end of the multi-core cable 1 is depicted in FIG. 1. The configurations of both ends of the multi-core cable 1 may be the same or different.

[0024] Figure 2 is a cross-sectional view of a multi-core cable 1. As shown in Figure 2, the multi-core cable 1 comprises a first wire 11, a second wire 12, a shield layer 13 covering the first wire 11 and the second wire 12, and a cable sheath 14 covering the shield layer 13. The multi-core cable 1 comprises multiple first wires 11 and multiple second wires 12. The first wire 11 comprises a conductor 11a and a sheath 11b. The second wire 12 comprises a conductor 12a and a sheath 12b. As shown in Figure 2, the outer diameters of the conductors 11a and 12a are different. Therefore, the outer diameters of the first wire 11 and the second wires 12 are also different. In the following description, when there is no need to distinguish between them, the first wire 11 and the second wires 12 may be simply referred to as wires 11 and 12, respectively.

[0025] The conductors 11a and 12a are not particularly limited, and for example, copper wire, plated copper wire, or copper alloy wire can be used. As conductors 11a and 12a, single wires or stranded wires made by twisting multiple conductor wires together may be used. The coatings 11b and 12b are also not particularly limited, and for example, insulating materials such as polyolefin resins, polyurethane, polyimide, perfluoroalkoxyalkane (PFA), and perfluoroethylene propene copolymer (FEP) can be used.

[0026] The outer diameter of conductor 11a may be, for example, 50 μm or more and 1 mm or less. The outer diameter of conductor 12a may be smaller than that of conductor 11a, for example, 10 μm or more and 1 mm or less, 20 μm or more and 200 μm or less, 30 μm or more and 100 μm or less, or 30 μm or more and 70 μm or less. The outer diameters of conductors 11a and 12a are appropriately selected, for example, depending on the application of the multi-core cable 1.

[0027] Figure 3 is a plan view of the connection point between the wires 11 and 12 and the substrate 21. Figure 3 shows two first wires 11 and two second wires 12, but the number of wires 11 and 12 is not particularly limited as long as there is at least one of each. As shown in Figure 3, the insulation 11b is removed from the front end of the first wire 11, exposing the conductor 11a. The insulation 12b is removed from the front end of the second wire 12, exposing the conductor 12a. In this specification, the exposed conductors 11a and 12a at the ends of the wires 11 and 12 are also referred to as exposed portions E. Multiple terminals 23 are provided in parallel on the upper surface 21U of the substrate 21. The upper surface 21U corresponds to the first surface of the substrate 21 in this disclosure. The multiple terminals 23 correspond to each of the multiple wires 11 and 12. As shown in Figure 3, the exposed portions E of the corresponding wires 11 and 12 are electrically connected to the terminals 23. The exposed portion E and terminal 23 are connected by solder 30.

[0028] (Manufacturing method for multi-core cables) Next, a method for manufacturing a multi-core cable according to one embodiment of the present disclosure will be described in accordance with the configuration of the multi-core cable 1. Figure 4 is a perspective view showing one step of the method for manufacturing a multi-core cable according to one embodiment of the present disclosure. Figure 4 shows the step of connecting electric wires 11 and 12 to corresponding terminals 23 on a substrate 21. As shown in Figure 4, of the electric wires 11 and 12 that extend parallel to each other in the forward direction, the first electric wire 11 is located at the leftmost and rightmost positions, and the two second electric wires 12 are located between the first electric wires 11. The covering 11b and 12b are removed from parts of each electric wire 11 and 12 to form exposed portions E. Hereafter, for the purpose of explanation, the exposed portion E of the rightmost first electric wire 11 may be referred to as exposed portion E1, and the exposed portion E of the second electric wire 12 adjacent to the first electric wire 11 may be referred to as exposed portion E2.

[0029] The method for manufacturing a multi-core cable according to this embodiment includes an arrangement step and a connection step. In the arrangement step, the exposed portions E of each electric wire 11, 12 and solder 30 are placed on a plurality of terminals 23 of a substrate 21. In the embodiment shown in Figure 4, solder 30 is placed on the terminals 23, and the exposed portions E are placed on the solder 30.

[0030] Next, in the connection process, the flexible member 40 is pressed against the exposed portion E and pressed toward the substrate 21, while the conductors 11a and 12a are heated using a non-contact method to melt the solder 30 and solder them. In the embodiment shown in Figure 4, a hot air blower 50 is used as a non-contact heating method to heat the wires 11 and 12 by blowing hot air onto them, and the exposed portion E is heated by heat conduction. Through this connection process, multiple terminals 23 and the exposed portions E of multiple wires 11 and 12 corresponding to the multiple terminals 23 are connected all at once.

[0031] The role of the flexible member 40 will be further explained with reference to Figure 5. Figure 5 is a cross-sectional view of the substrate 21 and electric wires 11 and 12 in the VV wire in Figure 4, showing the state in which the flexible member 40 is pressed against the exposed portion E of the electric wires 11 and 12 during the connection process. As shown in Figure 5, when the substrate 21 is placed on a horizontal plane Sh with its upper surface 21U facing upward, the height H1 of the top 12T of the exposed portion E1 of the second electric wire 12, which is placed on the terminal 23, and the height H2 of the top 11T of the exposed portion E2 of the first electric wire 11, which is placed on the horizontal plane Sh, are different. In other words, the height of the top of the exposed portion E placed on the terminal 23 is not uniform.

[0032] The flexible member 40 can be easily deformed when pressed against the exposed portion E. Therefore, as shown in Figure 5, the flexible member 40 can simultaneously contact the exposed portions E1 and E2, which have different top heights, and press the exposed portions E1 and E2 toward the substrate 21. In the state shown in Figure 5, by heating the conductors 11a and 12a to melt the solder 30 and solder them, the exposed portions E of the conductors 11a and 12a, which have different outer diameters, can be connected to multiple terminals 23 all at once in good condition.

[0033] The effects of the manufacturing method for multi-core cables of this disclosure will be explained in more detail with reference to embodiments relating to comparative examples. Figure 6 is a diagram showing the connection process relating to the first comparative example, and, like Figure 5, is a cross-sectional view when connecting the exposed portions E of the electric wires 11 and 12 to the terminals 23. As shown in Figure 6, in the first comparative example, the electric wires 11 and 12 and the terminals 23 are connected using a heater tip 61. This embodiment employs a pulse heat method in which the electric wires 11 and 12 are heated and soldered while being pressed toward the substrate 21 by the heater tip 61. However, since the heater tip 61 is typically made of metal or ceramic, it cannot be easily deformed like the flexible member 40. Therefore, in this embodiment, where there are exposed portions E1 and E2 with uneven top heights, as shown in Figure 6, when the heater tip 61 hits exposed portion E1, which has a relatively high top height, the heater tip 61 cannot descend any further, and the heater tip 61 does not come into contact with exposed portion E2, which is at a relatively lower position. As a result, the exposed portion E2 may not be sufficiently pressed and heated, potentially leading to a poor connection between the exposed portion E2 and the terminal 23.

[0034] Next, we will refer to an embodiment relating to another comparative example. Figure 7 shows the connection process relating to the second comparative example. In this embodiment, a cushioning material 62 is placed between the heater chip 61 and the electric wires 11 and 12. According to this embodiment, unlike the first comparative example described above, the cushioning material 62 can be easily deformed, so that the exposed portion E1 and exposed portion E2 can be simultaneously pressed toward the substrate 21. However, while the cushioning material 62 can be easily deformed, it is made of a material with low thermal conductivity, so the heat generated from the heater chip 61 is not easily transferred to the electric wires 11 and 12. As a result, the cycle time may increase and productivity may decrease.

[0035] Referring again to an embodiment of the present disclosure shown in Figures 4 and 5, according to this embodiment, the flexible member 40 can simultaneously press exposed portions E1 and E2, which have different top heights, toward the substrate 21. Furthermore, since the heating of the wires is performed by a non-contact method such as hot air rather than a contact method such as a heater tip, the low thermal conductivity of the flexible member 40 does not affect the cycle time. As described above, according to this embodiment, multiple wires with non-uniform heights can be connected to the substrate simultaneously.

[0036] In this embodiment, the substrate 21 may be a rigid substrate or an FPC (Flexible Printed Circuit).

[0037] Solder 30 may be a low-melting-point solder. The melting point of solder 30 may be 180°C or lower, 170°C or lower, 160°C or lower, or 150°C or lower. The lower limit of the melting point of solder 30 is not particularly limited, but it could be, for example, 100°C.

[0038] The flexible member 40 is not particularly limited and may be a plate made of a material such as silicone or urethane. The Shore A hardness of the flexible member 40 may be 10° to 70°. The thickness of the flexible member 40 may be 0.2 mm to 1.0 mm.

[0039] Examples of non-contact methods for heating the exposed portion E include heating with hot air, heating the conductor by resistance heating by passing an electric current through it, and inductive heating of the conductor by a magnetic field. Heating with hot air allows for easy control of the heating area and helps avoid damage to surrounding connecting components and wire insulation.

[0040] The embodiments to which the multi-core cable manufacturing method of this disclosure is applied are not limited to cases where wires of different diameters are connected to a substrate simultaneously, as in the embodiments described above. Hereinafter, modifications of the substrate and wire configurations to which the manufacturing method of this disclosure is applied will be described with reference to the drawings.

[0041] Figure 8 shows the configuration of the substrate and wires according to the first modified example. As shown in Figure 8, in this modified example, a plurality of terminals 23 are provided on the substrate 121, and a conductor 11a is connected to each of the plurality of terminals 23. In this modified example, the outer diameter of all conductors 11a may be the same. The upper surface of the substrate 121 has a step, and a first region A1 and a second region A2 which is lower in height from the horizontal plane Sh than the first region A2 are provided. Terminals 23 are arranged in both the first region A1 and the second region A2. In this modified example, although the outer diameter of all conductors 11a is the same, terminals 23 are provided in both the first region A1 and the second region A2 which are at different heights from the horizontal plane Sh. Therefore, the height of the top of the conductor 11a located in the first region A1 is different from the height of the top of the conductor 11a located in the second region A2. That is, the height of the tops of the conductors 11a located on the plurality of terminals 23 is not uniform. Even in such a configuration, by applying the multi-core cable manufacturing method of this disclosure described above, the plurality of terminals 23 and the corresponding exposed portions of the wires can be connected all at once.

[0042] Figure 9 shows the configuration of the substrate and wires according to the second modified example. As shown in Figure 9, in this modified example, the upper surface of the substrate 221 is inclined with respect to the horizontal plane Sh. In this modified example, any two regions of the upper surface of the substrate 221 have different heights from the horizontal plane Sh. Therefore, for example, as shown in Figure 9, the portion of the upper surface of the substrate 221 where the leftmost terminal 23 is located can be considered as the first region A1, and the portion where the adjacent terminal 23 is located can be considered as the second region A2. In this case, the height of the top of the conductor 11a located in the first region A1 is different from the height of the top of the conductor 11a located in the second region A2. That is, the height of the tops of the conductors 11a located on multiple terminals 23 is not uniform. Even in such a configuration, by applying the multi-core cable manufacturing method of this disclosure described above, multiple terminals 23 and the corresponding exposed portions of wires can be connected all at once.

[0043] Figure 10 shows the configuration of the substrate and wires according to the third modified example. As shown in Figure 10, the upper surface of the substrate 321 is curved in this modified example. In this modified example as well, for example, the area where the leftmost terminal 23 is located can be considered as the first region A1, and the area where the adjacent terminals 23 are located can be considered as the second region A2. In this case, the height of the top of the conductor 11a located in the first region A1 is different from the height of the top of the conductor 11a located in the second region A2. That is, the height of the tops of the conductors 11a located on multiple terminals 23 is not uniform. Even in such a configuration, by applying the multi-core cable manufacturing method of this disclosure described above, multiple terminals 23 and the corresponding exposed portions of the wires can be connected all at once. In the example shown in Figure 10, the entire upper surface of the substrate 321 is curved, but this disclosure can also be applied in the same way to a configuration in which the upper surface of the substrate is partially curved and terminals are provided on that curved surface.

[0044] Figure 11 shows the configuration of the substrate and wires according to the fourth modified example. As shown in Figure 11, in this modified example, connection points for the conductor 11a and terminals 24 are provided on the lower surface 421D of the substrate 421. Therefore, in this modified example, although the upper surface 421U of the substrate 421 is flat and the outer diameter of each wire is the same, when the substrate 421 is placed on a horizontal plane Sh with the upper surface 421U facing upward, the height of the tops of the conductors 11a arranged on the multiple terminals 23 on the upper surface 421U is not uniform. Even in such a configuration, by applying the multi-core cable manufacturing method of this disclosure described above, the multiple terminals 23 and the corresponding exposed portions of the wires can be connected all at once. The components arranged on the lower surface 421D are not limited to the conductor 11a and terminals 24, but can be any member. In this modified example, the lower surface 421D is flat, but similar to the upper surface of the substrate in the first to third modified examples described above, the lower surface 421D may have steps, inclines, or curved surfaces.

[0045] Furthermore, in the method for manufacturing a multi-core cable according to this disclosure, heating of the exposed portion by a non-contact method is performed by heating a first portion of the electric wire that extends in a first direction from the exposed portion, and conducting heat from the conductor of the first portion to the exposed portion. After the connection step, a cutting step of cutting the first portion may be further included. For example, in the configuration shown in Figure 4, the forward direction corresponds to the first direction, and the portions 11F and 12F of the electric wires 11 and 12 that extend forward from the exposed portion E correspond to the first portion. As shown in Figure 4, the hot air blower 50 heats the first portions 11F and 12F, and heats the exposed portion E (exposed portions E1 and E2) by conducting heat from the conductors 11a and 12a of the first portions 11F and 12F to the exposed portion E. Note that although Figure 4 shows the first portions 11F and 12F to be heated with the covering still attached, the covering of the first portions 11F and 12F to be heated may be removed. Then, in the cutting process following the connection process, for example, the wires 11 and 12 are cut at the position of the VV wire in Figure 4 to remove the first parts 11F and 12F. As a result of this cutting process, at the ends of the multiple wires 11 and 12, for example, as shown in Figure 3, the end of the exposed portion E and the end of the solder 30 are formed on the same plane. The expression "formed on the same plane" here should be understood as meaning that a cut surface is formed by cutting the wires 11 and 12 and the solder 30 together at a predetermined position as described above, and does not necessarily mean that the cut surface of the solder 30 and the ends of the wires 11 and 12 are formed on the exact same plane.

[0046] Since the flexible member 40 is pressed against the exposed portion E, it is difficult to heat the exposed portion E directly. Therefore, a method can be adopted in which the first portions 11F and 12F located near the exposed portion E are heated, and the exposed portion E is heated by heat conduction through the conductors 11a and 12a. In this case, the first portions 11F and 12F, which are directly heated, tend to become hot, and there is a possibility that the insulation 11b and 12b of the electric wires 11 and 12 may be damaged. Therefore, by leaving the product portion on the side opposite to the first portions 11F and 12F relative to the exposed portion E, and cutting the first portions 11F and 12F after the connection process, damage to the product portion can be avoided.

[0047] This disclosure also relates to the multi-core cable described above. Specifically, a multi-core cable 1 according to one embodiment of this disclosure comprises a plurality of electric wires 11, 12 and a substrate 21. Each of the plurality of electric wires 11, 12 includes conductors 11a, 12a, sheathing 11b, 12b covering the conductors 11a, 12a, and exposed portions E where the conductors 11a, 12a are exposed when the sheathing 11b, 12b is removed. A plurality of terminals 23 corresponding to each of the plurality of electric wires 11, 12 are provided on the first surface 21U of the substrate 21. The terminals 23 and the exposed portions E are electrically connected by solder 30. When the substrate 21 is placed on a horizontal plane Sh with the first surface 21U facing upward, the heights of the tops 11T, 12T of the conductors 11a, 12a of the plurality of electric wires 11, 12 connected on the corresponding terminals 23 are not uniform.

[0048] In the multi-core cable 1 of this embodiment, the exposed portion E and the solder 30 may be formed on the same plane at the ends of the multiple wires 11 and 12. The ends of the wires that are not covered with solder are formed by cutting the wires after soldering. When heating the wires for soldering, the heat may damage the insulation of the wires. By cutting the wires at the heated points after soldering, damage to the product can be avoided.

[0049] Although the method for manufacturing a multi-core cable and the multi-core cable of this disclosure have been described above with reference to specific embodiments, this disclosure is not limited to these embodiments.

[0050] The above description illustrates an example where the wire is an insulated wire including a conductor and a sheath, but the wire is not limited to an insulated wire; for example, it may be a coaxial wire. Also, although an example was described in which multiple wires are covered by a shielding layer and cable sheath, the shielding layer and cable sheath are not essential in this disclosure. In other words, the multi-core cable of this disclosure may not have a shielding layer and cable sheath, and the wires may be exposed.

[0051] The above explanation shows an example where the substrate is rectangular in plan view, but the shape of the substrate is not particularly limited and may be polygonal or have curved sides. [Explanation of symbols]

[0052] 1. Multi-core cable 11. Power lines (first power line) 12. Power lines (second power lines) 11a, 12a Conductors 11b, 12b Covering 11T,12T top 11F, 12F first part E,E1,E2 Exposed part 13 Shield Layer 14 Cable sheath 21,121,221,321,421 circuit boards 21U,421U top surface 421D bottom surface 23 terminals 24 terminals 30 solder 40 Flexible members 50 Hot air machine 61 Heater Tips 62 Cushioning material A1 First area A2 Second area Sh horizontal plane

Claims

1. A method for manufacturing a multi-core cable comprising multiple electric wires and a circuit board, Each of the plurality of electric wires includes a conductor, a covering that covers the conductor, and an exposed portion where the conductor is exposed when the covering is removed. The first surface of the substrate is provided with multiple terminals corresponding to each of the multiple electric wires, When the substrate is placed on a horizontal surface with the first surface facing upward, the height of the top of the exposed portion located on the corresponding terminal is not uniform. The aforementioned manufacturing method is A placement step of placing the exposed portion and solder on the plurality of terminals, The connection step includes a step of connecting the multiple terminals and the exposed portions of the multiple electric wires corresponding to the multiple terminals all at once by pressing a flexible member against the exposed portion and pressing it toward the substrate, while heating the conductor by a non-contact method to melt the solder and solder them together. A method for manufacturing multi-core cables.

2. The method for manufacturing a multi-core cable according to claim 1, wherein the plurality of wires include a plurality of wires having different outer diameters for their conductors.

3. The first surface of the substrate has a first region and a second region, each having a different height from the horizontal plane. The terminals are provided in the first region and the second region, The method for manufacturing a multi-core cable according to claim 1, wherein in the connection step, the exposed portions of the corresponding plurality of electric wires are connected collectively to the terminals provided in the first region and the terminals provided in the second region.

4. The method for manufacturing a multi-core cable according to any one of claims 1 to 3, wherein the non-contact method is heating by hot air.

5. The heating of the exposed portion by the non-contact method is performed by heating a first portion of the electric wire that extends from the exposed portion in a first direction, and conducting heat from the conductor of that portion to the exposed portion. A method for manufacturing a multi-core cable according to any one of claims 1 to 3, further comprising a cutting step after the connection step, in which the electric wire is cut and the first portion is removed.

6. A multi-core cable comprising multiple wires and a circuit board, Each of the plurality of electric wires includes a conductor, a covering that covers the conductor, and an exposed portion where the conductor is exposed when the covering is removed. The first surface of the substrate is provided with multiple terminals corresponding to each of the multiple electric wires, The terminal and the exposed portion are electrically connected by solder. A multi-core cable in which, when the substrate is placed on a horizontal surface with the first surface facing upward, the top heights of the conductors of the plurality of electric wires connected to the corresponding terminals are not uniform.

7. The multi-core cable according to claim 6, wherein at the ends of the multiple electric wires, the ends of the exposed portions and the ends of the solder are formed on the same plane.

8. The multi-core cable according to claim 6 or 7, wherein the plurality of wires include wires whose outer diameters differ from each other.

9. The first surface of the substrate has a first region and a second region, each having a different height from the horizontal plane. The multi-core cable according to claim 6 or claim 7, wherein the terminals are provided in the first region and the second region, respectively.

10. The multi-core cable according to claim 9, wherein the first surface of the substrate has a step.

11. The multi-core cable according to claim 9, wherein the first surface of the substrate is inclined with respect to the horizontal plane.

12. The multi-core cable according to claim 9, wherein the first surface of the substrate has a curved surface.

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