A structure comprising a cable and a substrate, and a method for manufacturing the structure.

Abstract

To provide a structure capable of suppressing changes in characteristic impedance. [Solution] The structure 10 comprises a cable 20 and a substrate 50. The cable 20 comprises at least one core wire 22, an insulating portion 24 covering the core wire 22, and a shield portion 26 covering the insulating portion 24. A ground pad 56 is formed on the substrate 50. The shield portion 26 is soldered to the ground pad 56. The ground pad 56 has a predetermined length PL in the direction in which the shield portion 26 extends. The cable 20 is specified to have a constant predetermined impedance as its characteristic impedance. The difference between the maximum characteristic impedance and the predetermined impedance at the point from the tip of the shield portion 26 to a point three times the predetermined length PL (length L1) away, including the shield portion 26, is 5Ω or less.

Description

Technical Field

[0001] The present invention relates to a structure including a cable and a substrate.

Background Art

[0002] For example, Patent Document 1 discloses a structure of this type.

[0003] Referring to FIG. 7, the structure 90 of Patent Document 1 includes a cable 92 and a substrate 98. The cable 92 includes a core wire 93, an insulating portion 94 covering the core wire 93, a shield portion 95 covering the insulating portion 94, and a jacket 96 covering the shield portion 95. Various conductive pads 99 are formed on the substrate 98. The core wire 93 and the shield portion 95 are exposed from the jacket 96, and are each fixed and connected to the conductive pads 99.

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] In a conventional structure such as the structure 90 of Patent Document 1, the shield portion is connected to the conductive pad by pulse heating. Specifically, a heater chip pressurizes the shield portion and presses it against the conductive pad coated with solder, while heating and melting the solder, thereby soldering the shield portion to the conductive pad. According to the conventional connection by pulse heating, the characteristic impedance is likely to change at and near the portion of the shield portion where the heater chip is pressed and heated. As a result, there is a risk that signal transmission characteristics may deteriorate. For this reason, as the signal frequency increases, the demand for suppressing changes in characteristic impedance is becoming stronger.

[0006] Therefore, the present invention aims to provide a structure capable of suppressing changes in characteristic impedance. [Means for solving the problem]

[0007] The present invention provides a first manufacturing method, A method for manufacturing a structure comprising a cable and a substrate, A preparation step for preparing the cable and the substrate, wherein the cable comprises at least one core wire, an insulating portion covering the core wire, and a shielding portion covering the insulating portion, and the substrate has a ground pad formed on it with solder applied. A placement step of placing the shield portion of the cable on the solder on the substrate, The process includes a soldering step in which the shield portion and the solder are heated non-contact by electromagnetic induction, thereby melting the solder and soldering the shield portion to the ground pad. To provide a manufacturing method.

[0008] The present invention provides a second manufacturing method, which is the first manufacturing method, In the preparation step, the cable is bent to form a first portion and a second portion that extend parallel to each other. In the arrangement step, the part to be held, which is a part of the first part, is held by a holding member, thereby placing the second part on the substrate and the first part at a predetermined distance from the substrate. To provide a manufacturing method.

[0009] The present invention provides a third manufacturing method, which is a second manufacturing method, The predetermined distance is 0.35 mm or less. To provide a manufacturing method.

[0010] The present invention provides a first structure, A structure comprising a cable and a circuit board, The cable comprises at least one core wire, an insulating portion covering the core wire, and a shielding portion covering the insulating portion. The substrate has a ground pad formed on it. The shield portion is soldered to the ground pad. The ground pad has a predetermined length in the direction in which the shield portion extends. The aforementioned cable is specified to have a certain predetermined impedance as its characteristic impedance. The difference between the maximum characteristic impedance and the predetermined impedance in the portion from the tip of the shield portion to a position three times the predetermined length away, including the shield portion, is 5Ω or less. Provides a structure.

[0011] The present invention provides a second structure, which is a first structure, The aforementioned structure includes a retaining member, The cable has a portion to be held and a portion to be bent. The cable is bent at the bending portion, The part to be held is held by the holding member, The held portion and the substrate are separated by a predetermined distance. The bent portion is located between the retained portion and the shield portion which is soldered to the ground pad. Provides a structure.

[0012] The present invention provides a third structure, which is a second structure, The predetermined distance is 0.35 mm or less. Provides a structure. [Effects of the Invention]

[0013] The characteristic impedance of a cable has a great influence on the signal transmission characteristics. For this reason, it is desirable to maintain the characteristic impedance of the cable at a prescribed predetermined impedance regardless of the location. However, in general, when soldering the shield portion of a cable to a ground pad of a substrate, the characteristic impedance tends to change greatly from the predetermined impedance in the shield portion soldered to the ground pad and in the vicinity thereof due to heat and pressure. On the other hand, according to the cable of the present invention, a change in characteristic impedance caused by pressure during soldering is prevented, whereby the change in characteristic impedance of the shield portion soldered to the ground pad and the vicinity thereof is 5Ω or less. That is, according to the present invention, a structure capable of suppressing a change in characteristic impedance can be provided.

[0014] Further, according to the manufacturing method of the present invention, the shield portion is soldered to the ground pad without applying pressure, for example, by IH (Induction Heating) reflow. According to this soldering method, a change in characteristic impedance in the shield portion and the vicinity thereof can be suppressed to 5Ω or less. That is, according to the present invention, a manufacturing method suitable for manufacturing the structure of the present invention can be provided. [Brief Description of the Drawings]

[0015] [Figure 1] FIG. 1 is a perspective view schematically showing a structure according to an embodiment of the present invention. A hidden contour of a shield portion of a cable of the structure is drawn with a broken line. [Figure 2] FIG. 2 is a diagram showing steps of manufacturing the structure of FIG. 1. [Figure 3] FIG. 3 is a side view schematically showing the structure in the soldering step of FIG. 2. [Figure 4] FIG. 4 is a side view showing a cable bent in the preparation step of FIG. 2. [Figure 5] FIG. 5 is a side view showing a first modification of the structure of FIG. 3. A hidden contour of the cable is drawn with a broken line. [Figure 6] FIG. 6 is a side view showing a second modification of the structure of FIG. 3. A hidden contour of the cable is drawn with a broken line. [Figure 7] This is a cross-sectional view showing the structure of Patent Document 1. [Modes for carrying out the invention]

[0016] As shown in Figure 1, the structure 10 according to an embodiment of the present invention comprises a cable 20 and a substrate 50. The substrate 50 in this embodiment is a circuit board mounted on an electronic device (not shown). One end of the cable 20 shown in this embodiment is electrically connected to the electronic device via the substrate 50. The other end of the cable 20 is connected to a counterpart electronic device (not shown). The cable 20 transmits high-frequency signals between the electronic device and the counterpart electronic device via the substrate 50. The structure 10 of this embodiment functions as described above. However, the present invention is not limited thereto and is applicable to various structures. For example, the structure 10 may comprise two or more cables 20 arranged in the lateral direction (Y direction).

[0017] In this embodiment, the cable 20 extends along the front-rear direction perpendicular to the lateral direction and is connected to the upper surface of the substrate 50 in the vertical direction perpendicular to both the lateral and front-rear directions. In this embodiment, the front-rear direction is the X direction. In this embodiment, "forward" is the +X direction and "backward" is the -X direction. In this embodiment, the vertical direction is the Z direction. In this embodiment, "upward" is the +Z direction and "downward" is the -Z direction. The terms lateral direction, front-rear direction, vertical direction, etc., do not indicate an absolute positional relationship with respect to the ground, but merely indicate a relative positional relationship when the direction in which the illustrated cable 20 extends is defined as the front-rear direction.

[0018] The cable 20 in this embodiment is a typical coaxial cable. More specifically, the cable 20 is a coaxial thin wire. The cable 20 comprises a single core wire 22 made of a conductor, an insulating portion 24 made of an insulator that covers the core wire 22 in a vertical plane (YZ plane) perpendicular to the front-rear direction, a shield portion 26 made of a conductor that covers the insulating portion 24 in a vertical plane, and an outer sheath 28 made of an insulator that covers the shield portion 26 in a vertical plane. However, the present invention is not limited thereto. As long as the cable 20 comprises a core wire 22, a shield portion 26, and an insulating portion 24 that insulates the core wire 22 and the shield portion 26 from each other, the structure of the cable 20 is not particularly limited.

[0019] For example, the number of core wires 22 may be two or more. More specifically, the cable 20 may be a twisted pair cable or a parallel pair cable. That is, the cable 20 only needs to include at least one core wire 22, an insulating part 24 covering the core wire 22, and a shielding part 26 covering the insulating part 24. The shielding part 26 may be formed from metal foil or a braid made of metal wires.

[0020] In this embodiment, the core wire 22 is the part that transmits high-frequency signals, and the shield part 26 is the part that protects the core wire 22 from electromagnetic interference. The cable 20 has a characteristic impedance when the core wire 22 transmits high-frequency signals. Generally, the characteristic impedance varies depending on the part of the cable 20. On the other hand, the characteristic impedance of the cable 20 has a significant effect on the transmission characteristics of high-frequency signals. For this reason, the characteristic impedance of a typical cable is defined by a standard specification. The cable 20 is specified to have a certain predetermined impedance as its characteristic impedance, similar to a typical cable. The predetermined impedance of the cable 20 is, for example, 90Ω.

[0021] The substrate 50 of this embodiment has a rectangular flat plate shape perpendicular to the vertical direction. Various conductive patterns are formed on the substrate 50. For example, signal pads 52 and ground pads 56 are formed on the substrate 50. The signal pads 52 are connected to electronic equipment (not shown) via conductive wires (not shown). The ground pads 56 are grounded to a ground pattern (not shown). The substrate 50 of this embodiment has the above-described structure. However, the present invention is not limited thereto. The structure of the substrate 50 can be modified as needed. For example, the substrate 50 may have two or more signal pads 52, each corresponding to two or more cables 20.

[0022] In this embodiment, the core wire 22 of the cable 20 is soldered to the signal pad 52 of the circuit board 50. The shield portion 26 of the cable 20 in this embodiment is soldered to the ground pad 56 of the circuit board 50. The ground pad 56 has a predetermined length PL in the front-rear direction in which the shield portion 26 extends. The difference between the maximum characteristic impedance and the predetermined impedance in the portion from the tip (front end) of the shield portion 26 to a position three times the predetermined length PL (i.e., length L1) away, including the shield portion 26, is 5Ω or less.

[0023] It is desirable to maintain the characteristic impedance of the cable 20 at a specified predetermined impedance, regardless of the location. For this reason, the core wire 22 is located at the center of the cable 20 in the vertical plane (YZ plane), and the shield portion 26 is arranged in a circular shape with the core wire 22 at the center in the vertical plane. However, with conventional technology, when soldering the shield portion 26 of the cable 20 to the ground pad 56 of the substrate 50, the positional relationship between the core wire 22 and the shield portion 26 in the vertical plane is easily altered due to heat and pressure in and around the shield portion 26 soldered to the ground pad 56. As a result, the characteristic impedance is prone to deviating significantly from the predetermined impedance.

[0024] On the other hand, according to this embodiment, as will be explained below, changes in characteristic impedance caused by pressure applied during soldering are prevented, and as a result, the change in characteristic impedance of the shield portion 26 soldered to the ground pad 56 and its vicinity is 5Ω or less. In other words, according to this embodiment, a structure 10 capable of suppressing changes in characteristic impedance can be provided.

[0025] The following describes a manufacturing method for a structure 10 comprising a cable 20 and a substrate 50 according to this embodiment.

[0026] Referring to Figure 2 in conjunction with Figure 1, the structure 10 of this embodiment is manufactured through three steps: a preparation step (STEP 1), an arrangement step (STEP 2), and a soldering step (STEP 3). However, the manufacturing method shown in Figure 2 and the manufacturing method described below are merely examples and can be modified as needed.

[0027] Referring to Figure 2 in conjunction with Figure 3, in the preparation step, first, the cable 20 and the circuit board 50 are prepared. Next, the outer sheath 28, shield portion 26, and insulating portion 24 of the front end of the cable 20 are sequentially stripped, exposing the core wire 22, insulating portion 24, and shield portion 26 to the outside of the cable 20 as shown in Figure 3. Solder 58 is also applied to the signal pad 52 and ground pad 56 of the circuit board 50.

[0028] To summarize the above description, the manufacturing method of this embodiment includes a preparation step of preparing a cable 20 and a substrate 50, wherein the cable 20 comprises at least one core wire 22, an insulating portion 24 covering the core wire 22, and a shield portion 26 covering the insulating portion 24, and the substrate 50 has a ground pad 56 formed on it with solder 58 applied.

[0029] Next, in the placement process, the cable 20 is placed on the substrate 50. Specifically, the outer sheath 28 is placed on the upper surface of the substrate 50 such that the core wire 22 is positioned directly above the signal pad 52 on which solder 58 has been applied, and the shield portion 26 is positioned directly above the ground pad 56 on which solder 58 has been applied. At this time, it is desirable that the solder 58 on the ground pad 56 is in sufficient contact with the placed shield portion 26.

[0030] To summarize the above description, the manufacturing method of this embodiment includes a placement step of placing the shield portion 26 of the cable 20 on the solder 58 of the substrate 50.

[0031] Next, in the soldering process, the core wire 22 and the shield portion 26 are soldered to the signal pad 52 and the ground pad 56, respectively.

[0032] Referring to Figure 3, according to this embodiment, the shield portion 26 is soldered without pressure using IH reflow soldering with a soldering device 80. The soldering device 80 shown in Figure 3 is a schematic representation of an actual device and comprises a coil 82 and a magnetic flux concentrater 88. The coil 82 is connected to an AC power supply (not shown) and winds around the magnetic flux concentrater 88. When a high-frequency current HC is passed through the coil 82, a magnetic flux FL is generated in the magnetic flux concentrater 88. At this time, eddy currents are generated in conductive parts such as the shield portion 26 and solder 58 located near the magnetic flux concentrater 88, causing the shield portion 26 and solder 58 to generate heat. As a result, the solder 58 melts and the shield portion 26 is soldered to the ground pad 56.

[0033] On the other hand, according to the conventional technology, the shield portion 26 is soldered by pulse heat. Specifically, the shield portion 26 is pressed against the ground pad 56 to which solder 58 has been applied by a heater tip (not shown), and the solder 58 is heated and melted, thereby soldering the shield portion 26 to the ground pad 56. With conventional pulse heat connection, the shield portion 26 is prone to deformation due to the pressure. In addition, the insulating portion 24 is prone to partial melting and deformation due to the heat applied from the heater tip. As a result, the positional relationship between the core wire 22 and the shield portion 26 in the vertical plane (YZ plane) changes significantly, and this makes it easy for the characteristic impedance of the part of the shield portion 26 that is pressed against and heated by the heater tip and its vicinity to change. According to this embodiment, it is possible to prevent the change in characteristic impedance that occurs in the conventional technology.

[0034] To summarize the above explanation, the manufacturing method of this embodiment includes a soldering step in which the shield portion 26 and solder 58 are heated non-contact by electromagnetic induction, thereby melting the solder 58 and soldering the shield portion 26 to the ground pad 56.

[0035] According to the soldering method of this embodiment, deformation of the shield portion 26 due to pressure can be prevented. In addition, since heat due to electromagnetic induction is not generated in the insulating portion 24, deformation of the insulating portion 24 can be suppressed. As a result, the positional relationship between the core wire 22 and the shield portion 26 in the vertical plane (YZ plane) is maintained in the same positional relationship as before the soldering process (see Figure 2). More specifically, even after the soldering process, the shield portion 26 is substantially arranged in a circular shape centered on the core wire 22 in the vertical plane. As a result, the change in characteristic impedance in and near the shield portion 26 can be suppressed to 5Ω or less. In other words, according to this embodiment, a manufacturing method suitable for manufacturing the structure 10 of this embodiment can be provided.

[0036] The core wire 22 of the cable 20 may be soldered to the signal pad 52 by pulse heat after the shield portion 26 has been soldered. More specifically, the core wire 22 may be pressed against the solder 58 on the signal pad 52 under pressure, while the solder 58 is heated and melted. Alternatively, the core wire 22 may also be soldered by IH reflow without pressure. For example, if the insulation portion 24 and the shield portion 26 are thin, the solder 58 may be applied thickly to the signal pad 52 and brought into contact with the positioned core wire 22. In this state, the core wire 22 and the shield portion 26 may be soldered simultaneously by IH reflow.

[0037] According to this embodiment, the shield portion 26 and the solder 58 are heated non-contact by the IH reflow described above. However, the present invention is not limited thereto. As long as the shield portion 26 and the solder 58 can be heated non-contact by electromagnetic induction, the specific heating method is not particularly limited. Furthermore, the structure of the soldering apparatus 80 is not particularly limited. The soldering apparatus 80 may be configured to solder the shield portions 26 of two or more cables 20 simultaneously.

[0038] The manufacturing method described above is particularly suitable for coaxial thin wires. However, the manufacturing method described above is not limited to cable 20, which is a coaxial cable, but can be applied to various types of cables.

[0039] The following describes some variations of the manufacturing method of this embodiment.

[0040] Referring to Figure 4 in conjunction with Figure 3, depending on the thickness of the outer sheath 28 of the cable 20, when the cable 20 is placed on the substrate 50 in a straight line along the front-to-back direction, the shield portion 26 may be far from the ground pad 56. Even if a thick layer of solder 58 is applied to the ground pad 56, the shield portion 26 may not make contact with the solder 58. In such cases, the cable 20 may be bent before being placed on the substrate 50. That is, a bent cable 20A may be used instead of the cable 20.

[0041] Referring to Figure 4, the cable 20A may be bent at two bends 38. This bending process forms a first section 32 and a second section 36 in the cable 20A. The first section 32 mainly includes the outer sheath 28. The second section 36 includes the shield section 26 exposed from the outer sheath 28. Both the first section 32 and the second section 36 extend along the front-to-back direction. That is, the first section 32 and the second section 36 extend parallel to each other within tolerance. Furthermore, this bending process has little effect on the positional relationship between the core wire 22 and the shield section 26 in the vertical plane (YZ plane).

[0042] In this modified example, the lower end of the shield portion 26 of the second portion 36 is located below the lower end of the outer sheath 28 of the first portion 32. The core wire 22 of the cable 20A is also bent. The lower end of the core wire 22 is located below the lower end of the shield portion 26 of the second portion 36 and extends along the front-to-back direction. However, the present invention is not limited thereto. For example, the core wire 22 may be bent as needed. The position of the lower end of the shield portion 26 of the second portion 36 should be set to an appropriate position where the shield portion 26 contacts the solder 58 when the cable 20A is placed on the substrate 50 (see Figure 5).

[0043] The cable 20A shown in Figure 4 has the same structure as cable 20 (see Figure 3), except that it has been bent. However, the present invention is not limited thereto. For example, the outer sheath 28 of cable 20A may be considerably thicker than the outer sheath 28 of cable 20 (see Figure 3).

[0044] To summarize the above explanation, according to this modified example, in the preparation step (see Figure 2), the cable 20A is bent to form a first portion 32 and a second portion 36 that extend parallel to each other on the cable 20A.

[0045] Referring to Figure 5, the cable 20A may be positioned on the upper surface of the substrate 50 using a retaining member 40. For example, the retaining member 40 may be a locator fixed to the upper surface of the substrate 50. In this case, the cable 20A has a retained portion 34. The retained portion 34 is part of the first portion 32 of the cable 20A. By holding the retained portion 34 with the retaining member 40, the cable 20A can be easily positioned in the designated location. More specifically, the first portion 32 can be positioned at a predetermined distance PD from the upper surface of the substrate 50. As a result, the second portion 36 of the cable 20A can be positioned on the substrate 50 such that the shield portion 26 is in contact with the solder 58 of the ground pad 56.

[0046] To summarize the above explanation, according to this modified example, in the placement process (see Figure 2), the retained portion 34, which is part of the first portion 32, is held by the retaining member 40, thereby placing the second portion 36 on the substrate 50 and placing the first portion 32 at a predetermined distance PD away from the substrate 50.

[0047] According to the manufacturing method of the modified example described above, the structure 10A according to the first modified example can be manufactured. The structure 10A comprises a cable 20A, a holding member 40, and a substrate 50. The cable 20A has a held portion 34 and a bent portion 38. The cable 20A is bent at the bent portion 38. The held portion 34 is held by the holding member 40. The held portion 34 and the substrate 50 are separated by a predetermined distance PD. The bent portion 38 is located between the held portion 34 and the shield portion 26 soldered to the ground pad 56.

[0048] In this modified example, the predetermined distance PD is preferably 0.35 mm or less. Coaxial thin wires are hard and difficult to bend. By reducing the size of the holding member 40 and setting the predetermined distance PD to a small size of 0.35 mm or less, the amount of bending of the coaxial thin wire can be reduced. However, the present invention is not limited thereto. For example, the predetermined distance PD may be set according to the application of the holding member 40.

[0049] This embodiment can be modified in various ways, in addition to the various modifications already described.

[0050] For example, referring to Figure 6, the structure 10B according to the second modification comprises a cable 20B, a holding member 40, and a substrate 50. Comparing Figure 6 with Figure 5, the held portion 34 of cable 20B is different from the held portion 34 of cable 20A. More specifically, the held portion 34 of cable 20B includes the rear end of the shield portion 26. Apart from this difference, structure 10B has a similar structure to structure 10A and can be manufactured using the same manufacturing method as structure 10A.

[0051] Although the best embodiment of the present invention has been described above, it will be obvious to those skilled in the art that the embodiment can be modified without departing from the spirit of the invention, and such embodiments fall within the scope of the present invention. [Explanation of Symbols]

[0052] 10,10A,10B Structure 20, 20A, 20B Cables 22 core wires 24 Insulation part 26 Shield section 28 Outer cover 32 Part 1 34 Holding part 36 Part 2 38 Bent section 40 Retaining member 50 circuit boards 52 signal pads 56 Ground Pad 58 Handa 80 Soldering equipment 82 coils 88 Magnetic flux concentrater HC high frequency current FL magnetic flux

Claims

1. A method for manufacturing a structure comprising a cable and a substrate, A preparation step for preparing the cable and the substrate, wherein the cable comprises at least one core wire, an insulating portion covering the core wire, and a shielding portion covering the insulating portion, and the substrate has a ground pad formed on it with solder applied. A placement step of placing the shield portion of the cable on the solder on the substrate, The process includes a soldering step in which the shield portion and the solder are heated non-contact by electromagnetic induction, thereby melting the solder and soldering the shield portion to the ground pad. Manufacturing method.

2. A manufacturing method according to claim 1, In the preparation step, the cable is bent to form a first portion and a second portion that extend parallel to each other. In the arrangement step, the part to be held, which is a part of the first part, is held by a holding member, thereby placing the second part on the substrate and the first part at a predetermined distance from the substrate. Manufacturing method.

3. A manufacturing method according to claim 2, The predetermined distance is 0.35 mm or less. Manufacturing method.

4. A structure comprising a cable and a circuit board, The cable comprises at least one core wire, an insulating portion covering the core wire, and a shielding portion covering the insulating portion. The substrate has a ground pad formed on it. The shield portion is soldered to the ground pad. The ground pad has a predetermined length in the direction in which the shield portion extends. The aforementioned cable is specified to have a certain predetermined impedance as its characteristic impedance. The difference between the maximum characteristic impedance and the predetermined impedance in the portion from the tip of the shield portion to a position three times the predetermined length away, including the shield portion, is 5 ohms or less. structure.

5. The structure according to claim 4, The aforementioned structure includes a retaining member, The cable has a portion to be held and a portion to be bent. The cable is bent at the bending portion, The part to be held is held by the holding member, The held portion and the substrate are separated by a predetermined distance. The bent portion is located between the retained portion and the shield portion which is soldered to the ground pad. structure.

6. The structure according to claim 5, The predetermined distance is 0.35 mm or less. structure.

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