High-frequency signal transmission device and high-frequency signal transmission cable

Abstract

A high-frequency signal transmission cable (4) has a dielectric layer (70), and a first wiring layer (71) and a second wiring layer (72) provided so as to sandwich the dielectric layer (70). At least M differential transmission lines are provided in the first wiring layer (71), where M represents a natural number of 2 or more. A first ground line group composed of at least 2 x M first ground lines (81) is provided in the first wiring layer (71), and a second ground line group composed of at least M second ground lines (82) is provided in the second wiring layer (72). At least two first ground lines (81) included in the first ground line group are assigned to each of the M differential transmission lines without repetition, and at least one second ground line (82) included in the second ground line group is assigned to each of the M differential transmission lines without repetition. Each differential transmission line is sandwiched by the at least two first ground lines (81), and is provided opposite to the at least one second ground line (82).

Description

Technical Field

[0001] This invention relates to a high-frequency signal transmission device and a high-frequency signal transmission cable. Background Technology

[0002] For high-frequency signal transmission cables, measures to improve isolation between differential transmission lines and suppress crosstalk are important. Patent Document 1 relates to a flexible wiring cable in which a first grounding pattern is arranged in the same plane, sandwiching a high-speed transmission line. This first grounding pattern is connected to the upper and lower first and second grounding layers via through wiring. This reduces crosstalk and electromagnetic noise, and also facilitates impedance matching through grounding potential stabilization (paragraph 0044 of the patent document).

[0003] Patent document 2 discloses the following: a differential transmission line is provided on the upper surface of a dielectric substrate, a coplanar conductor layer is provided sandwiching the transmission line, a lower conductor layer is provided on the lower surface of the dielectric substrate in a substantially integral manner, the coplanar conductor layer and the lower conductor layer are electrically connected by a through conductor, and the spacing of the through conductor and the thickness of the dielectric substrate are set to be less than 1 / 4 of the wavelength of the high-frequency signal transmitted by the differential transmission line.

[0004] Patent document 3 discloses the following: a signal conductor pattern is provided between the upper ground conductor pattern and the lower ground conductor pattern, and a hole is provided between the signal conductor patterns arranged in parallel with each other.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2007-234500

[0008] Patent Document 2: Japanese Patent Application Publication No. 2003-224408

[0009] Patent Document 3: Japanese Patent Application Publication No. 2016-92561 Summary of the Invention

[0010] As disclosed in Patent Document 1, a grounding wire is provided between the differential transmission lines on the same plane, and a grounding layer (so-called GND plate) is disposed opposite to the differential transmission lines through a dielectric layer; this is the usual practice. From the perspective of convention or ease of pattern formation, the grounding wire is shared between adjacent differential transmission lines, and the GND plate is shared between all differential transmission lines. The inventors of this application have re-examined this conventional construction and discovered the significance of providing a technology suitable for further developments in transmitting signals at higher frequencies.

[0011] According to one aspect of the present invention, a high-frequency signal transmission cable has a dielectric layer, a first wiring layer and a second wiring layer disposed in a manner sandwiching the dielectric layer, and at least M differential transmission lines are provided in the first wiring layer, wherein M represents a natural number greater than 2. The first wiring layer also has a first grounding wire group consisting of at least 2 × M first grounding wires, and the second wiring layer has a second grounding wire group consisting of at least M second grounding wires. At least two first grounding wires included in the first grounding wire group are distributed non-repeatingly with respect to each of the M differential transmission lines, and at least one second grounding wire included in the second grounding wire group is distributed non-repeatingly with respect to each of the M differential transmission lines. Each differential transmission line is sandwiched by the at least two first grounding wires and disposed opposite to the at least one second grounding wire.

[0012] At least two first grounding wires provided between a certain differential transmission line can be electrically connected to a second grounding wire provided opposite to the differential transmission line via through wiring.

[0013] Other embodiments of the high-frequency signal transmission device of the present invention include: a high-frequency signal transmission cable of any of the preceding claims; and a connector for electrically connecting the high-frequency signal transmission cable through one end thereof, the connector having an isolator and a plurality of contact terminals arranged along the width direction of the isolator and supported by the isolator.

[0014] In some embodiments, the connector includes a plurality of contact terminals comprising at least M pairs of signal contact terminals and at least 2×M ground contact terminals, wherein at least two ground contact terminals are distributed non-repeatingly among the at least M pairs of signal contact terminals, and each pair of signal contact terminals is sandwiched between the at least two ground contact terminals.

[0015] The high-frequency signal transmission device includes: a first connector electrically connected to a high-frequency signal transmission cable via its first end; and a second connector electrically connected to the high-frequency signal transmission cable via its second end. The connectors are identical. A plug component is mounted at one end of the high-frequency signal transmission cable to facilitate the connection between the cable and the connector. Contact pieces for the signal line of the differential transmission line and a contact piece for the first ground line are disposed between the plug protrusions of the plug component. The connector's isolator has a hole for inserting the plug protrusions of the plug component.

[0016] Invention Effects

[0017] According to one aspect of the invention, a technology capable of adapting to further developments in transmitting signals at higher frequencies can be provided. Attached Figure Description

[0018] Figure 1 This is a schematic perspective view of a high-frequency signal transmission device according to one aspect of the present invention.

[0019] Figure 2 This is a rough bottom view of the cable assembly.

[0020] Figure 3 This is a schematic diagram showing a general and partial cross-sectional structure of the FPC.

[0021] Figure 4 This is a rough, partial bottom view showing one end of the FPC.

[0022] Figure 5 This is a schematic three-dimensional view of the connector, showing its front side.

[0023] Figure 6 This is a schematic three-dimensional view of the connector, showing its rear side.

[0024] Figure 7 This is a schematic exploded perspective view of the connector, mainly showing the state in which eight mounting components and nine fixing accessories are separated from the isolator body and moved rearward.

[0025] Figure 8 This is a schematic diagram showing the state in which the four contact terminals of the GSSG arrangement are respectively accommodated in the four receiving slots on the lower plate of the isolator body.

[0026] Figure 9 It means along Figure 8 A schematic diagram of the approximate cross section of the single-dash line X9-X9.

[0027] Figure 10 It is a schematic exploded perspective view of the mounting components, showing the state after the conductive components have been removed from the mounting components.

[0028] Figure 11 This is a rough top view of the installed components.

[0029] Figure 12 It is along Figure 11 A simplified cross-sectional view of the single-dotted dashed line X12-X12.

[0030] Figure 13 This is a partial rear view of the connector.

[0031] Figure 14 This is a schematic diagram showing the state where an FPC is inserted into the connector and the two sides are electrically connected.

[0032] Figure 15 This is a rough partial top view of other types of FPCs.

[0033] Figure 16 It means along Figure 15 A schematic diagram of the approximate cross section of the single-dash line X16-X16.

[0034] Figure 17 This is a schematic diagram showing the connection status between the connector's contact terminals and the signal line's contact pads.

[0035] Figure 18 This is a graph representing the simulation results.

[0036] Figure 19 This is a graph representing the simulation results.

[0037] Figure 20 This is a graph representing the simulation results. Detailed Implementation

[0038] The following is a reference. Figures 1 to 20 The various embodiments and features are described below. Those skilled in the art can combine the various embodiments and / or features without further explanation and can understand the multiplicative effects obtained based on such combinations. Repeated descriptions between embodiments are omitted in principle. The accompanying drawings are primarily for the purpose of describing the invention and are simplified for ease of drawing. The features are not only applicable to the high-frequency signal transmission cables disclosed in this application, but should be understood as general features applicable to various other high-frequency signal transmission cables not disclosed in this specification. In this specification, terms such as "first," "second," etc., are used as needed to distinguish connectors and other similar components, but terms indicating relative positional relationships and directions (front, back, left, right, up, down) can also be used alternatively or additionally to distinguish similar components.

[0039] The high-frequency signal transmission device 9 includes a (first) connector 1, a (second) connector 2, and a cable assembly 3. Connectors 1 and 2 are identical in construction; therefore, there is no need to distinguish between them in the description. In other words, a description of one connector can be directly applied to the other, and vice versa. The configuration of connectors 1 and 2 will be described in detail below.

[0040] The cable assembly 3 includes an FPC (Flexible Printed Circuit) 4, a (first) plug component 5 installed at end 41 of the FPC 4 to facilitate connection between the FPC 4 and connector 1, and a (second) plug component 6 installed at end 42 of the FPC 4 to facilitate connection between the FPC 4 and connector 2. Furthermore, the FPC 4 is a non-limiting example of a high-frequency signal transmission cable. The FPC may also be alternatively referred to as a flat cable.

[0041] Connectors 1 and 2 are mechanically connected to plug components 5 and 6, respectively, and electrically connected to FPC4 (specifically, the contact patch group arranged at the ends of FPC4). Plug components 5 and 6 are plug components with the same structure; therefore, there is no need to distinguish between them in the description. Based on the relationship between FPC4 and / or plug components 5 and 6, connectors 1 and 2 can also be referred to as receptacle connectors. Furthermore, plug components 5 and 6 are optional components and can be omitted.

[0042] FPC4 is a laminate of dielectric layer 70, (first) wiring layer 71, (second) wiring layer 72, cover layer 73 covering wiring layer 71, and cover layer 74 covering wiring layer 72 (see reference). Figure 3 The FPC4 is a flexible cable capable of being bent into a U-shape, but non-flexible cables can also be used. The dielectric layer 70 can be a resin sheet with a specified relative permittivity, such as LCP (liquid crystal polymer) or polyimide. Similarly, the coating layers 73 and 74 can be, for example, resin films of LCP (liquid crystal polymer) or polyimide. The coating layers are removed from the ends 41 and 42 of the FPC4; as a result, the floating capacitance between the signal line 85 and the first ground line 81 (described later) changes compared to the portion covered by the coating layers. The wiring included in the wiring layers 71 and 72 can be metal foils such as copper foil.

[0043] The wiring layer 71 has at least M (M represents a natural number greater than 2) differential transmission lines 8 and at least 2 × M first grounding lines 81 (referred to as the first grounding line group). The signal lines 85 of the differential transmission lines 8 and the first grounding lines 81 are arranged in the same plane. The wiring layer 72 has at least M second grounding lines 82 (referred to as the second grounding line group). Typically, the number of second grounding lines 82 included in the second grounding line group is half the number of first grounding lines 81 included in the first grounding line group, but this is not necessarily the case. Furthermore, in the illustrated case, M = 8, but this is not a limitation.

[0044] As a feature of the present invention, for each of the M differential transmission lines 8, at least two first grounding wires included in the first grounding wire group are non-repeatingly assigned, and for each of the M differential transmission lines 8, at least one second grounding wire included in the second grounding wire group is non-repeatingly assigned. As a result, each differential transmission line 8 is sandwiched between at least two (assigned) first grounding wires 81 (specifically, in the same plane) and is disposed opposite to at least one (assigned) second grounding wire 82 (specifically, separated by a dielectric layer 70) (see reference). Figure 3According to this configuration, crosstalk generated when the ground wire or GND plate is shared between differential transmission lines is suppressed. Furthermore, when the ground wire or GND plate is shared between differential transmission lines, there is a concern that signals may leak from one differential transmission line to other differential transmission lines via the ground wire or GND plate (e.g., common-mode noise (or current) transmitted from the device to the ground wire), which cannot be fully avoided even when using a differential transmission method.

[0045] In some cases, a signal transmission line consisting of at least five wirings—four wirings in the first plane (i.e., two signal lines 85 and two first ground lines 81 of the differential transmission line 8) and one wiring in the second plane (i.e., one second ground line 82)—forms a single channel. The number of channels for the signal transmission lines is also denoted by M. Advantageously, the ground lines are not shared between adjacent signal transmission lines along the FPC4 (e.g., the entire length of the FPC4).

[0046] In each signal transmission line, preferably, each first ground wire 81 is electrically connected to a common second ground wire 82 via multiple through wirings 86, so as to stabilize the potential of the first ground wire 81 and the second ground wire 82 (refer to...). Figure 4 Furthermore, the first grounding wire 81 is narrower than the second grounding wire 82. Moreover, in a signal transmission line, it is preferable that the number of through-wires 86 for connecting one first grounding wire 81 to the second grounding wire 82 and the number of through-wires 86 for connecting other first grounding wires 81 to the second grounding wire 82 are the same, and that they are spaced at the same interval, but this is not a limitation. Multiple individual third grounding wires (not shown) can also be formed on the coating layer 73 in the same manner as the second grounding wire 82.

[0047] Signal line 85 can be shaped such that the portion exposed not covered by the covering layer 73 is narrower than the portion covered by the covering layer 73 (see reference). Figure 4 The widths W1 and W2 are specified. For example, the contact pieces 85a at both ends of the signal line 85 are shaped to be smaller than the width of the intermediate wiring portion 85b extending between these contact pieces 85a. This allows the absorption of the difference in relative permittivity between the coating layer 73 and air, thus maintaining uniform signal transmission characteristics. Furthermore, although setting the contact pieces 85a to a small width requires higher calibration accuracy for the electrical connection between FPC4 and connectors 1 and 2, this problem can be avoided by using a plug component.

[0048] The first grounding wire 81 can be shaped such that the portion exposed not covered by the covering layer 73 is wider than the portion covered by the covering layer 73 (see reference). Figure 4(Widths W3 and W4). For example, the first ground wire 81 is shaped such that the contact pieces 81a at both ends are wider than the intermediate wiring portion 81b extending between these contact pieces, and the spacing between the contact pieces 81a of the first ground wire 81 and the contact piece 85a of the signal line 85 is narrowed according to the larger contact piece 81a. This allows the absorption of the difference in relative permittivity between the coating layer 73 and air, thus maintaining uniform signal transmission characteristics. Furthermore, even though the contact piece 81a is set to be large in width, the contact piece 85a is still small in width, thus requiring higher calibration accuracy for the electrical connection between FPC4 and connectors 1 and 2. In addition, the width of the contact piece 85a of the signal line 85 can be less than 2 / 3 or less than 1 / 2 of the width of the contact piece 81a of the first ground wire 81.

[0049] The contact piece 85a of the signal line 85 can be configured to be further away from the end of the FPC4 than the contact piece 81a of the first ground line 81. As a result, when the contact portion of the contact terminal 12 of the connector 1 contacts the contact piece 85a of the signal line 85, the length of the open-circuit stub formed between these contact positions and the top of the signal line 85 can be shortened.

[0050] return Figure 1 Continuing the explanation. Plug components 5 and 6 are mounted on the ends 41 and 42 of the FPC4. Plug component 5 has a plug body 51, a pair of plug protrusions 52 located at both ends of the plug body 51 in the width direction, and a locking portion 53 located between the pair of plug protrusions 52 in the width direction of the plug body 51. The plug body 51 is a frame with space for the FPC4 to pass through. Therefore, if the FPC4 is inserted into the plug component 5, the contact pieces of the FPC4 (i.e., the contact piece 81a of the first ground wire 81 and the contact piece 85a of the signal wire 85) are arranged along the width direction of the FPC4 between the pair of plug protrusions 52 extending forward from the plug body 51.

[0051] In detail, the contact pad arrangement units, formed by a pair of contact pads 81a (of the first ground wire 81) sandwiching a pair of contact pads 85a (of the signal wire 85), are arranged along the width direction of the FPC4. In each arrangement unit, the contact pads 85a are positioned further away from the end of the FPC4 than the contact pads 81a. The description of the plug component 5 also applies to the plug component 6, and its description is omitted (reference numerals 5, 51 to 53 are replaced by reference numerals 6, 65 to 67).

[0052] like Figures 5 to 7As shown, connector 1 has an isolator 11 and a plurality of contact terminals 12 arranged along the width direction of isolator 11 and supported by isolator. Isolator 11 is made of any insulating resin, supports contact terminals 12, and is shaped as a socket for receiving FPC 4. Isolator 11 has an isolator body 21 and at least M mounting members 22 mounted relative to isolator body 21 and arranged along the width direction of isolator 11. As an option, M+1 fixing accessories 23 are provided for mounting mounting members 22 to isolator body 21. In addition, two fixing accessories 24 are provided for fixing isolator 11 to a mounting base (e.g., motherboard or daughterboard) for mounting connector 1. Furthermore, the width direction of connector 1 / isolator 11 is equal to the width direction of FPC 4, and similarly, equal to the arrangement direction of contact terminals 12 and the arrangement direction of mounting members 22.

[0053] The plurality of contact terminals 12 include at least M pairs (M represents a natural number greater than 2) of signal contact terminals 12S and at least 2 × M ground contact terminals 12G. Furthermore, each pair of signal contact terminals 12S is non-overlapping with two ground contact terminals 12G included in the at least 2 × M ground contact terminals 12G, with each pair of signal contact terminals 12S sandwiched between two ground contact terminals 12G. That is, M (M represents a natural number greater than 2) arrangement units C1 to C8, formed by sandwiching a pair of signal contact terminals 12S between a pair of ground contact terminals 12G, are arranged along the width direction of the isolator 11. Since there are no shared ground contact terminals between adjacent pairs of signal contact terminals 12S in the width direction of the connector 1, signal crosstalk is reduced.

[0054] Each mounting component 22 can be configured to have a total of four contact terminals 12, supported between two grounding contact terminals 12G and sandwiching a pair of signal contact terminals 12S. Contact terminals 12 are provided on the isolator 11 by mounting M mounting components 22 relative to the isolator body 21. The signal transmission line formed by the combination of four contact terminals 12 is supported by different mounting components 22, improving electrical isolation between signal transmission lines and promoting the reduction of crosstalk. Furthermore, the number of mounting components 22 is not limited to M=8, but can also be a natural number of M=2 or more.

[0055] The main body 21 of the isolation component has a front opening 21a on the FPC4 side (see reference). Figure 5 ) and the rear opening 21b, which is opposite to FPC4 (see reference) Figure 7 The frame has an upper plate 25, a lower plate 26, a left wall 27, and a right wall 28. Furthermore, the front is positioned from the connector 1 toward the FPC4, and the left and right sides are also defined based on this direction.

[0056] A recess 31 is provided on the upper surface of the upper plate 25, and a locking part 33 is provided on the bottom surface of the recess 31. A through hole 32 is provided adjacent to the left wall 27, through which the isolator body 21 passes in the front-to-back direction. Similarly, a through hole 32 is provided adjacent to the right wall 28, through which the isolator body 21 passes in the front-to-back direction. The plug protrusion 52 of the plug component 5 is inserted into these through holes 32 individually, which facilitates good alignment of the FPC4 with the connector 1. In addition, the through holes 32 are spatially connected to the front opening 21a of the isolator body 21, which prevents the isolator 11 from becoming too wide.

[0057] When the FPC4 is fully inserted into the connector 1 to the designated position, the locking portion 53 of the plug component 5 engages with the locking portion 33 of the isolator body 21. The specific engaging mechanism between the locking portion 33 and the locking portion 53 can be configured in various ways by those skilled in the art. For example, the locking portion 53 is a pivotable claw that rises to a height on the guide ramp 33m (the rearward raised ramp) of the locking portion 33 according to the insertion of the FPC4 into the connector 1, and then contacts the locking surface 33n extending downward from the top of the guide ramp 33m.

[0058] The lower plate 26 is provided with accommodating slots 26g side by side. In particular, a predetermined number (four) of accommodating slots 26g are arranged in a unit group along the width direction of the spacer body 21. Each accommodating slot 26g extends in the front-rear direction to accommodate the contact terminal 12 supported by the mounting member 22. For example, each accommodating slot 26g is divided by left and right walls extending in the front-rear direction and a bottom surface extending in the front-rear direction, and has openings at the top, front, and rear. The contact terminal 12 can be inserted into the accommodating slot 26g through the opening at the top. Depending on the shape of the contact terminal 12, it can also be inserted from the rear opening of the accommodating slot 26g. The spacing I1 of the accommodating slots 26g within the same unit group is less than the spacing I2 between unit groups, which is less than half of it. The number of accommodating slots 26g included in the unit set is the same as the number of contact terminals 12 supported by one mounting member 22.

[0059] Each contact terminal 12 has an arm 61 extending forward from the mounting member 22 in a cantilever beam shape, a fixing portion 62 fixed to the mounting member 22, and a contact portion 63 extending rearward from the mounting member 22 (see reference). Figure 7 , Figure 8The arm portion 61 includes an arm plate portion 61a and an arm rod portion 61b, which is positioned further away from the mounting component 22 and is narrower than the arm plate portion 61a. The arm plate portion 61a has a lateral width that gradually decreases as it extends forward. The arm rod portion 61b extends further forward from the front end of the arm plate portion 61a. The arm rod portion 61b extends obliquely forward and then obliquely downward, forming an arc-shaped contact portion 61c for contact with the contact pads of the FPC4. Due to the use of the arm rod portion 61b, higher accuracy is required for the calibration of the FPC4 and the contact pads, but this burden can be reduced by using a plug component.

[0060] The portion between the contact portion 61c of the contact terminal 12 and the front end 61d of the arm portion 61b functions as an open-circuit stub, which is unnecessary from a signal transmission point of view, but is provided to prevent the contact terminal 12 from bending due to collision with the FPC4. The contact portion 61c of the contact terminal 12, supported by a common mounting member 22, is arranged on a straight line L1 parallel to the width direction of the isolator 11, but is not necessarily limited to this. Alternatively, by properly mounting the mounting member 22 relative to the isolator body 21, the contact portions 61c of all the contact terminals 12 provided on the isolator 11 can be arranged on the straight line L1.

[0061] When the mounting component 22 is installed relative to the isolator body 21, the arm 61 of the contact terminal 12 of the mounting component 22 is inserted into the receiving groove 26g (see reference). Figure 9 This allows resins with a relative permittivity greater than air (such as PBT (polybutylene terephthalate) or LCP (liquid crystal polymer)) to be positioned between adjacent contact terminals 12, enabling adjustment of the floating capacitance between adjacent contact terminals 12 and achieving good impedance matching with the FPC4. Because the contact terminals 12 slightly arch upwards from the receiving groove 26g at the arc-shaped contact portion 61c, electrical connection between the contact terminals 12 and the FPC4 is ensured.

[0062] The receiving groove 26g is shaped to deepen at the top (front end) side of the arm portion 61. Specifically, the receiving groove 26g has a rear groove portion 26g1 that accommodates the arm plate portion 61a of the contact terminal 12, and a front groove portion 26g2 that accommodates the open-circuit short wire of the contact terminal 12, the depth of the front groove portion 26g2 being greater than the depth of the rear groove portion 26g1. Thus, except for the arched portion of the contact portion 61c, the entire arm portion 61 is accommodated in the receiving groove 26g.

[0063] The width of the receiving groove 26g can be set (i.e., fine-tuned) relative to the width of the arm portion 61. Specifically, the receiving groove 26g has a first groove width for accommodating the arm plate portion 61a and a second groove width narrower than the first groove width for accommodating the arm rod portion 61b. Alternatively, the receiving groove 26g has a minimum groove width at the position corresponding to the contact portion 61c. This allows for an increase in the amount of resin between the contact terminals 12.

[0064] Furthermore, by contacting the FPC4, the arm 61 is pressed downwards, and the front end 61d of the arm 61 contacts the bottom surface of the receiving groove 26g. In this case, the FPC4 and the contact terminal 12 are in a pressing relationship with each other, and the two are more reliably electrically connected.

[0065] The fixing portion 62 of the contact terminal 12 has an exposed portion 62c that protrudes into the insertion hole 34 of the mounting member 22. The remaining portions 62a and 62b of the fixing portion 62 are embedded in the resin of the mounting member 22. The contact portion 63 extends rearward from the mounting member 22, but its length, thickness, bending method, and number of bends can be varied.

[0066] Mounting component 22 is a component with an insertion hole 34 for inserting conductive component 13 (see reference). Figures 10 to 12 The mounting component 22 is a cylindrical body having a front wall 35, a rear wall 36, a left wall 37, and a right wall 38, into which the conductive component 13 can be pressed. Furthermore, the insertion hole 34 is open on both the upper and lower sides. A recess 39 extending in the front-rear direction and opening on the right side is provided on the right wall 38. Similarly, a recess 39 extending in the front-rear direction and opening on the left side is provided on the left wall 37.

[0067] The conductive component 13 may be a component obtained by dispersing a conductive filler in an insulating resin. The conductive component 13 has a main body 13j and at least two protrusions 13p protruding downwards from the main body 13j. The main body 13j is a tapered component whose front-to-back width W4 decreases as it extends downwards. The protrusions 13p are blocks protruding downwards from the left and right ends of the main body 13j, and their lower surfaces contact the upper surface of the exposed portion 62c of the grounding contact terminal 12G. Furthermore, the (maximum) left-to-right width W3 of the conductive component 13 is the same as, slightly larger than, or slightly smaller than the interval between the left wall 37 and right wall 38 of the mounting component 22. Similarly, the (maximum) front-to-back width W4 of the conductive component 13 is the same as, slightly larger than, or slightly smaller than the interval between the front wall 35 and rear wall 36 of the mounting component 22. The vertical width W5 of the conductive component 13 varies depending on the presence or absence of the protrusions 13p.

[0068] If the conductive component 13 is inserted into the insertion hole 34 of the mounting component 22, each protrusion 13p of the conductive component 13 contacts the exposed portion 62c of the grounding contact terminal 12G located within the insertion hole 34. A space 13q is provided between the protrusions 13p, thus preventing electrical connection between the conductive component 13 and the signal contact terminal 12S.

[0069] The mounting (e.g., embedding) of the contact terminal 12 relative to the mounting member 22 can be achieved using insert molding. Injection molding is performed such that resin adheres to and solidifies the remaining portions 62a and 62b of the fixing portion 62 of the contact terminal 12. The aforementioned portion of the contact terminal 12 is disposed within a cavity divided by a fixed mold and a movable mold, then molten resin is supplied into the cavity, and the mold is cooled. This solidification of the molten resin within the cavity yields a mounting member 22 in which the contact terminal 12 is partially embedded. Furthermore, the insertion hole 34 is a space corresponding to a core disposed within the cavity during injection molding to fix the contact terminal 12.

[0070] Since the contact terminal 12 is supported by the mounting member 22, the mounting member 22 needs to be positioned relative to the isolator body 21. That is, the low positioning accuracy of the mounting member 22 in the isolator body 21 is due to the low positional accuracy of the contact terminal 12 in the connector 1. According to this view, in some cases, a fixing accessory 23 can be used to position the mounting member 22 in the isolator body 21.

[0071] The fixing accessory 23 has an insertion part 23a, protrusions 23b protruding to the left and right sides, and a bending part 23c (see reference). Figure 7 When the mounting components 22 are adjacent in the width direction of the spacer 11, the combination of the recesses 39 of the adjacent mounting components 22 forms an insertion path 22k for fixing the fitting 23 (see reference). Figure 13 The insertion portion 23a of the retaining accessory 23 is inserted (preferably pressed) into the insertion path 22k, restricting the displacement of the mounting member 22 within the isolator body 21. The insertion stop position of the retaining accessory 23 is determined by the collision between the protrusion 23b of the retaining accessory 23 and the rear surface of the mounting member 22, and the mounting member 22 is pressed from the rear by the protrusion 23b. The bending portion 23c is soft-soldered relative to the mounting base of the connector 1 by soft-melt welding. The retaining accessory 23 can be connected to the ground potential on the mounting base for mounting the connector 1. This improves the isolation between signal transmission lines in the connector 1. In some cases, the insertion portion 23a of the retaining accessory 23 is inserted into a groove provided in the isolator body 21, thereby effectively restricting the displacement of the retaining accessory 23.

[0072] When the plug component 5 is connected to the connector 1 for electrical connection of the FPC4 to the connector 1, the FPC4 can be smoothly guided into the connector 1 by the engagement of the plug protrusion 52 with the through hole 32. If the FPC4 is inserted into the isolator 11 via the front opening 21a, the FPC4 is positioned on the lower plate 26 of the isolator body 21. The contact portion 61c of the contact terminal 12 arches slightly upward from the receiving groove 26g. Therefore, the lower surface of the FPC4 contacts the upper surface of its contact portion 61c as the FPC4 is inserted, causing the contact portion 61c to be pressed downward. If the FPC4 is inserted to the designated position, contact is ensured between the contact portion 61c of each contact terminal 12 of the connector 1 and the contact pieces 81a, 85a of the FPC4 (see reference). Figure 14 Specifically, the contact portion 61c of the arm 61 of the signal contact terminal 12S contacts the contact piece 85a of the signal line 85. Similarly, the contact portion 61c of the arm 61 of the grounding contact terminal 12G contacts the contact piece 81a of the first grounding line 81.

[0073] As should be specifically noted, in the high-frequency signal transmission device 9 constructed from the combination of FPC4 and connectors 1 and 2, the ground potential is not shared between the various signal transmission lines. Specifically, the ground wire is not shared between the differential transmission lines 8 of FPC4. The grounding contact terminal 12G is not shared between the pair of signal contact terminals 12S of connectors 1 and 2 that are electrically connected to the differential transmission lines 8. In this way, the sharing of ground potential between the differential transmission lines is avoided in both FPC4 and connectors 1 and 2, thereby improving electrical isolation and enabling the suppression of crosstalk. Alternatively, the non-shared ground potential may not be implemented for both FPC4 and connectors 1 and 2, but only for FPC4 or only for connectors 1 and 2.

[0074] like Figures 15 to 17 As shown, it is also possible to form a first ground wire 81 and a signal wire 85 on the upper surface of the FPC4, and contact pieces 81a and 85a on the lower surface of the FPC4, connecting the two sides with independent through wiring. That is, the contact piece 81a of the first ground wire 81 and the contact piece 85a of the signal wire 85 do not need to be provided on the wiring layer 71. Although in Figures 15 to 17 Not shown in the image, but related to Figure 3 Similarly, a second grounding wire 82 is formed on the wiring layer 72.

[0075] Figure 18 This represents the simulation results related to insertion loss in high-frequency signal transmission devices (with connectors at both ends of the cable assembly). Figure 18 (a) represents the result when the first grounding wire is shared between adjacent differential transmission lines and the second grounding wire is shared between all differential transmission lines. Figure 18(b) represents the result of the method of the present invention. For example... Figure 18 As shown, in the present invention, ripple improvement is achieved at frequencies around 30 GHz.

[0076] Figure 19 The simulation results represent the crosstalk characteristics associated with high-frequency signal transmission devices (with connectors at both ends of the cable device). Figure 19 (a) represents the simulation results of NEXT (Near End Cross Talk), PE1 relates to this implementation, and CE1 relates to a comparative example. Figure 19 (b) represents the simulation results of FEXT (Far End Cross Talk), PE1 relates to this embodiment, and CE1 relates to a comparative example. Furthermore, Figure 19 (a) and Figure 19 In both cases of (b), the comparative example uses a cable arrangement in which a first grounding wire is shared between adjacent differential transmission lines (i.e., a first grounding wire is provided between adjacent differential transmission lines). Figure 19 (a) and Figure 19 As shown in (b), the crosstalk of PE1 is less than that of CE1. According to this embodiment, it has been confirmed that the reduction of crosstalk is promoted.

[0077] Figure 20 This represents the simulation results of crosstalk characteristics related to cable devices. Figure 20 (a) represents the simulation results of NEXT (Near EndCross Talk), PE1 relates to this implementation, and CE1 relates to a comparative example. Figure 20 (b) represents the simulation results of FEXT (FarEnd Cross Talk), PE1 relates to this embodiment, and CE1 relates to a comparative example. Furthermore, Figure 20 (a) and Figure 20 In both cases of (b), the comparative example uses a cable arrangement in which a first grounding wire is shared between adjacent differential transmission lines (i.e., a first grounding wire is provided between adjacent differential transmission lines). Figure 20 (a) and Figure 20 As shown in (b), the crosstalk of PE1 is less than that of CE1. According to this embodiment, it has been confirmed that the reduction of crosstalk is promoted.

[0078] Based on the above teachings, those skilled in the art can make various modifications to the embodiments. The shape of the contact terminal is not limited to the shape shown in the figure, and a structure in which one contact terminal has two or more contact portions can also be adopted. The contact terminals can also be arranged to electrically connect with the contact pieces on both sides of the FPC. Specifically, one side of the contact terminals is arranged to contact the contact pieces on the front side of the FPC, and the other side of the contact terminals is arranged to contact the contact pieces on the back side of the FPC. In this way, the FPC is not limited to having contact pieces on one side, and a structure in which contact pieces are provided on both sides can also be adopted.

[0079] Explanation of reference numerals in the attached figures

[0080] 1, 2: Connectors

[0081] 4: FPC

[0082] 5, 6: Plug components

[0083] 8: Differential transmission line

[0084] 9: High-frequency signal transmission device

[0085] 11: Isolation component

[0086] 12: Contact terminal (12G: Grounding contact terminal, 12S: Signal contact terminal)

[0087] 13: Conductive components

[0088] 21: Main body of the isolation component

[0089] 22: Installation components

[0090] 70: Dielectric layer

[0091] 71, 72: Wiring layers

[0092] 73, 74: Covering layer

[0093] 81: First grounding wire

[0094] 82: Second grounding wire

[0095] 85: Signal line.

Claims

1. A high-frequency signal transmission cable, comprising a dielectric layer and a first wiring layer and a second wiring layer disposed therebetween the dielectric layer, wherein at least M differential transmission lines are provided in the first wiring layer, wherein, M represents a natural number greater than 2, and the high-frequency signal transmission cable is characterized by... The first wiring layer is further provided with a first grounding wire group consisting of at least 2×M first grounding wires, and the second wiring layer is provided with a second grounding wire group consisting of at least M second grounding wires. Each of the M differential transmission lines is assigned two first ground wires from the first ground wire group, without repetition, and each of the M differential transmission lines is assigned one second ground wire from the second ground wire group, without repetition, thereby constituting M signal transmission lines. Each of the M signal transmission lines consists of five wirings: four wirings in the first plane and one wiring in the second plane. The four wirings are the two signal lines and the two first grounding lines of the differential transmission line, and the one wiring is the one second grounding line. In each of the M signal transmission lines, the differential transmission line is sandwiched between the two first grounding wires and is positioned opposite to the one second grounding wire. In each of the M signal transmission lines, the two first grounding wires are electrically connected to a common second grounding wire via multiple through wirings, and each of the two first grounding wires is narrower than the second grounding wire.

2. The high-frequency signal transmission cable according to claim 1, characterized in that, It also has a first resin coating layer covering the first wiring layer, wherein the signal lines of the differential transmission line are shaped such that the portion exposed not covered by the first coating layer is narrower than the portion covered by the first coating layer.

3. The high-frequency signal transmission cable according to claim 2, characterized in that, The signal lines of the differential transmission line are shaped such that the contact pieces at both ends are narrower than the intermediate wiring portion extending between these contact pieces, the contact pieces are not covered by the first coating layer, and the intermediate wiring portion is covered by the first coating layer.

4. The high-frequency signal transmission cable according to claim 3, characterized in that, The first grounding wire is shaped such that the portion exposed not covered by the first covering layer is wider than the portion covered by the first covering layer.

5. The high-frequency signal transmission cable according to any one of claims 1 to 4, characterized in that, The first grounding wire is shaped such that the contact pieces at both ends are wider than the intermediate wiring portion extending between these contact pieces, and the spacing between the contact pieces of the first grounding wire and the contact pieces of the signal line of the differential transmission line is narrowed according to the wider contact pieces.

6. The high-frequency signal transmission cable according to any one of claims 1 to 4, characterized in that, The width of the contact piece of the signal line of the differential transmission line is less than 2 / 3 or less than 1 / 2 of the width of the contact piece of the first grounding line.

7. The high-frequency signal transmission cable according to any one of claims 1 to 4, characterized in that, The contact piece of the signal line of the differential transmission line is configured to be further away from the end of the cable than the contact piece of the first grounding line.

8. The high-frequency signal transmission cable according to any one of claims 1 to 4, characterized in that, M represents a natural number greater than 4.

9. A high-frequency signal transmission device, characterized in that, have: The high-frequency signal transmission cable according to any one of claims 1 to 4; and A connector for electrically connecting the high-frequency signal transmission cable through one end thereof, the connector having an isolator and a plurality of contact terminals arranged along the width direction of the isolator and supported by the isolator.

10. The high-frequency signal transmission device according to claim 9, characterized in that, In the connector, The plurality of contact terminals includes M pairs of signal contact terminals and 2 × M grounding contact terminals. Each pair of signal contact terminals included in the M pairs of signal contact terminals is non-repeatingly assigned two grounding contact terminals included in the 2×M grounding contact terminals, with each pair of signal contact terminals sandwiched between the two grounding contact terminals.

11. The high-frequency signal transmission device according to claim 10, characterized in that, The isolator has an isolator body and at least M mounting components mounted relative to the isolator body and arranged along the width direction of the isolator.

12. The high-frequency signal transmission device according to claim 11, characterized in that, Each mounting component is configured such that four contact terminals of a pair of signal contact terminals are supported between the two grounding contact terminals.

13. The high-frequency signal transmission device according to claim 12, characterized in that, Each mounting component holds the conductive component that electrically connects the at least two grounding contact terminals to each other.

14. The high-frequency signal transmission device according to claim 13, characterized in that, The mounting component has an insertion hole for inserting the conductive component, the conductive component having at least two protrusions, each protrusion contacting the exposed portion of the grounding contact terminal located within the insertion hole of the mounting component.

15. The high-frequency signal transmission device according to claim 9, characterized in that, It has a plug component installed at one end of the high-frequency signal transmission cable to facilitate the connection between the high-frequency signal transmission cable and the connector.

16. The high-frequency signal transmission device according to claim 15, characterized in that, The plug component has at least two plug protrusions, between which are disposed the contact piece of the signal line of the differential transmission line and the contact piece of the first grounding line.

17. The high-frequency signal transmission device according to claim 16, characterized in that, The connector's isolator has a hole for the plug protrusion of the plug component to be inserted.

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