Cable device and manufacturing method thereof

Abstract

A cable device (9) comprises: a flexible cable (2) including a plurality of cable strips (35) formed in accordance with one or more slits (21); and one or more bundling implements (5) for bundling the plurality of cable strips (35) in a stacked state. The plurality of cable strips (35) include at least two signal transmitting strips (35s), each including at least one transmission path for a high frequency signal. The cable device (9) additionally includes spacers (80) inserted between the signal transmitting strips (35s) in a stacking direction of the cable strips (35), at one or more bundling locations associated with the one or more bundling implements (5).

Description

[Technical field]

[0001] The present disclosure relates to a cable device for transmitting high frequency signals and a method for manufacturing the same. [Background technology]

[0002] It is known to bundle flexible wiring fins formed by slits in a flexible wiring board, as disclosed in Patent Document 1. This increases the degree of deformation freedom of the flexible wiring board. Patent Documents 2 and 3 also disclose devices of the same type as Patent Document 1.

[0003] Patent Document 4 discloses that a spacer is disposed between the first and second flexible boards to match the characteristic impedance to the characteristic impedance between the tester and the probe needle. Patent Document 5 discloses that a spacer is disposed so as to maintain the distance between opposing wiring patterns at a predetermined distance or more at a bent portion of a printed wiring board. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-66086 A [Patent Document 2] JP 2010-40929 A [Patent Document 3] Patent No. 4215775 [Patent Document 4] JP 2008-210839 A [Patent Document 5] JP 2010-153540 A Summary of the Invention [Problem to be solved by the invention]

[0005] There is a need to bundle multiple cable strips divided by one or more slits (usually multiple slits) with a binder in a flexible cable such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable). However, if multiple cable strips are bundled with a binder as described in Patent Documents 1 to 3, there is a risk that the desired transmission characteristics of high frequency signals through the flexible cable cannot be obtained due to coupling via capacitance between the high frequency signal transmission path of one cable strip and the high frequency signal transmission path of another cable strip. [Means for solving the problem]

[0006] A cable device according to an embodiment of the present disclosure includes a flexible cable having a plurality of cable strips formed according to one or more slits, the plurality of cable strips including two or more signal transmission strips each including at least one transmission path for a high-frequency signal, one or more binders for binding the plurality of cable strips in a stacked state, and a spacer inserted between the signal transmission strips in the stacking direction of the cable strips at one or more binding points by the at least one binder. The spacer may be separate from the binder. The spacer may include a dummy strip of the flexible cable.

[0007] A cable device according to another embodiment of the present disclosure includes a flexible cable including a plurality of cable strips formed according to one or more slits, the plurality of cable strips including two or more signal transmission strips each including at least one high-frequency signal transmission path, and one or more spacer strips that can be arranged between the signal transmission strips in the stacking direction of the cable strips at one or more bundling points where the plurality of cable strips are bundled in a stacked state. The spacer is separate from the bundling tool.

[0008] A manufacturing method for a cable device according to a further embodiment of the present disclosure includes a step of manufacturing or preparing a flexible cable having a plurality of cable strips formed according to one or more slits, the plurality of cable strips including two or more signal transmission strips each including at least one transmission path for a high-frequency signal, a step of bundling the plurality of cable strips in a stacked state with one or more binders, and a step of inserting spacers between the signal transmission strips in the stacking direction of the cable strips at one or more bundling points with the at least one binder.

[0009] In some embodiments, the transmission path of the high-frequency signal includes one or more signal lines formed on the first surface of the dielectric layer and a ground layer formed on the second surface of the dielectric layer, and the spacer is (selectively) attached to the signal transmission strip on the same second surface side as the ground layer. In some cases where an adhesive is used, the spacer is attached to the signal transmission strip via an adhesive on the same second surface side as the ground layer, and the spacer is not attached to the signal transmission strip via an adhesive on the same first surface side as the signal line. In some cases, the adhesive can be formed so as to overlap at least the ground layer (e.g., a partial region or the entire area of ​​the ground layer) on the same second surface side as the ground layer. The attachment efficiency of the spacer and the reduction of the influence of the relative dielectric constant of the adhesive by the ground layer are simultaneously achieved.

[0010] In some embodiments, the spacer includes one or more spacer strips. The spacer strips may be laminated to at least the signal transmission strips. When the spacer includes two or more spacer strips, a single layer of signal transmission strips and a single layer of spacer strips may be laminated in a stacking direction of the cable strips at one or more tie locations.

[0011] In some embodiments, the plurality of cable strips includes at least one dummy strip that is not provided with a high-frequency signal transmission path in addition to the two or more signal transmission strips. The at least one dummy strip is disposed on the outermost layer in the stacking direction of the plurality of cable strips at one or more bundling points by at least one bundling device. Additionally or alternatively, the dummy strip is used as the spacer or spacer strip described above.

[0012] In some embodiments, each of the two or more signal transmission strips includes a dielectric layer, one or more differential signal lines formed on a first surface of the dielectric layer, at least a pair of ground lines formed on either side of the one or more differential signal lines on the first surface of the dielectric layer so as to sandwich the one or more differential signal lines, a ground layer formed on a second surface of the dielectric layer, and at least a pair of through electrodes individually connecting each ground line of the at least one pair of ground lines to the ground layer.

[0013] In some embodiments, the slit formed in the flexible cable has a first slit end nearer to the first end of the flexible cable and a second slit end nearer to the second end of the flexible cable, and the length of the spacer strip is at least half, preferably at least 70%, or at least 80%, or at least 90%, or equal to or longer than the length of the slit between the first and second slit ends, where equal to or longer than the length of the slit means a length within a range of 0.95 to 1.05 times the length of the given length.

[0014] In some embodiments, the spacer has a relative dielectric constant of 2 or less, and / or a thickness of the spacer is 0.1 mm or more, and / or the material of the spacer is nonwoven fabric, cloth, or paper.

[0015] In some embodiments, the one or more ties are tubular members (eg, spiral tubes or braided tubes with slits) that encase a stack including the multiple cable strips and spacers.

[0016] In some embodiments, the plurality of cable strips are bundled together in a subset, and the subsets may be classified based on a signal transmission direction. Effect of the Invention

[0017] According to one aspect of the present disclosure, even when multiple cable strips are bundled with a binder, degradation of the transmission characteristics of high-frequency signals caused by a flexible cable can be suppressed or avoided. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic perspective view of a high-frequency signal transmission device according to an embodiment of the present disclosure, in which plug members fixed to both ends of an FPC are each connected to a connector on a wiring board. [Diagram 2] FIG. 2 is a schematic top view of an FPC with a plug member. [Diagram 3] FIG. 2 is a schematic partial cross-sectional view of an FPC and spacer laminate, with slits formed between adjacent FPC strips cutting the laminate through its thickness. [Figure 4] FIG. 2 is a schematic partial enlarged view of one end of an FPC, in which contacts are arranged in the width direction of the FPC. [Diagram 5] FIG. 2 is a schematic cross-sectional view of a cable device taken along dashed line XX in FIG. 1, in which FPC strips and spacer strips are alternately stacked with the FPC strips bound by a binder. [Figure 6] FIG. 2 is a schematic diagram showing one embodiment of a spacer. [Figure 7] FIG. 13 is a schematic diagram showing another embodiment of the spacer. [Figure 8] FIG. 13 is a schematic diagram showing yet another embodiment of the spacer. [Figure 9] FIG. 2 is a schematic perspective view of a high-frequency signal transmission device, in which a binder and a spacer are omitted compared to FIG. 1. [Figure 10] FIG. 4 illustrates the variation of insertion loss with frequency for a cable arrangement according to the present disclosure. [Figure 11] FIG. 4 illustrates the variation of return loss with frequency for a cable assembly in accordance with the present disclosure. [Figure 12] FIG. 10 illustrates the variation of insertion loss with frequency for the cable arrangement shown in FIG. [Figure 13] FIG. 10 illustrates the variation of return loss with respect to frequency for the cable arrangement shown in FIG. [Figure 14] FIG. 10 is a diagram showing the variation in insertion loss with respect to frequency when the FPC strip in FIG. 9 is bound by a binder. [Figure 15] FIG. 10 is a diagram showing the variation in return loss with respect to frequency when the FPC strip in FIG. 9 is bound by a binding tool. [Figure 16] FIG. 1 is a schematic cross-sectional view of a laminate in which spacer strips are laminated to both sides of an FPC strip. [Figure 17] 1A to 1C are schematic diagrams showing variations regarding attachment of a spacer to an FPC. [Figure 18] FIG. 17 is a diagram showing the measurement results of the insertion loss for FIG. 16. [Figure 19] FIG. 17 is a diagram showing the measurement results of the return loss for FIG. 16. [Figure 20] FIG. 2 is a schematic diagram for explaining the manufacturing method according to the present disclosure. [Figure 21] 1 is a schematic cross-sectional view of a cable assembly, showing a state in which a cable strip includes a dummy strip, and the dummy strip is disposed on the top layer of a laminate at a binding point using a binding tool. [Figure 22] FIG. 1 is a schematic cross-sectional view of a cable arrangement in which dummy strips are used as spacer strips. [Figure 23] FIG. 13 is a schematic diagram showing a variation in which a spacer is integrally provided with the fastener (i.e., the fastener has a spacer). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Various embodiments and features will be described below with reference to Figs. 1 to 23. Those skilled in the art can combine the embodiments and / or features without the need for excessive explanation, and can also understand the synergistic effect of this combination. In principle, overlapping explanations between embodiments will be omitted. The reference drawings are primarily intended to describe the invention, and are simplified for the convenience of drawing. Each feature is not only effective for the cable device and the manufacturing method thereof disclosed in this application, but is understood as a universal feature that is also applicable to various other cable devices and manufacturing methods thereof that are not disclosed in this specification.

[0020] As shown in FIG. 1, the high-frequency signal transmission device 1 includes a cable device 9, a first connector 41, and a second connector 42. The cable device 9 includes an FPC 2, a binder 5, and a spacer 80 described later. The FPC 2 is an example of a flexible cable, and is not limited to an FPC (Flexible Printed Circuit) but may be an FFC (Flexible Flat Cable). The FPC 2 has a plurality of FPC strips (cable strips) 35 formed in accordance with the slits 21 (see also FIGS. 2 and 3). Two or more FPC strips 35 are bound by the binder 5. This allows the FPC 2 to have a width that is reduced from its unbound width W2 (or the width at both ends). By bundling the FPC strip 35 in such a cable device 9, for example, the cooling efficiency within the equipment (hereinafter simply referred to as the equipment) in which the high-frequency signal transmission device 1 is built is improved, or the freedom of wiring design within the equipment is increased, or the efficiency of assembly work for the equipment (for example, the routing and connection of various cables or wires) is promoted.

[0021] The FPC strips 35 can be bundled by a binder 5 for each subset of the FPC strips 35. The subsets of the FPC strips 35 can be divided based on the transmission direction of the high-frequency signals. For example, as can be seen from FIG. 1, a first subset G1 can be assigned for signal transmission in a first direction (upstream), and a second subset G2 can be assigned for signal transmission in a second direction (downstream). The second direction is the opposite direction to the first direction. This makes it possible to suppress crosstalk between high-frequency signals propagating in different directions.

[0022] The number of subsets of the FPC strip 35 is necessarily two or more, but other numbers such as three or four can be used as long as the number of subsets is increased. Although the number of binders 5 increases with an increase in the number of subsets, the use of a versatile binder 5 (e.g., a spiral tube or a braided tube with slits) can avoid or suppress the increase in cost. The FPC 2 has a plurality of binding portions 31 corresponding to the subsets, and gaps 32 are formed between them. The binding portions 31 are curved in an arc shape.

[0023] The number of binders 5 attached to one subset of FPC strips 35 is one or more, and in some cases, two or three or more, which allows the binder 31 to be formed sufficiently long and uniform. Note that the binder 31 has flexibility similar to the FPC 2 and the FPC strip 35. Therefore, the binder 31 can be bent to an extent that the influence on the transmission characteristics of high-frequency signals of the cable device 9 is not caused or is negligible.

[0024] In the illustrated example, the FPC 2 includes ten FPC strips 35. The FPC strips 35 are bound by a binder 5 in groups of five. Three binders 5 are attached to each subset. When ten FPC strips 35 are bound as a set by the binder 5, the degree of bending of the FPC strips 35 varies depending on the position of the FPC strips 35 in the width direction of the FPC 2. It may become necessary to impart high flexibility to the FPC 2 because the FPC strips 35 bend relatively greatly. By bundling the FPC strips 35 by the binder 5 for each subset as described above, such problems can be avoided or suppressed. Note that if the number of FPC strips 35 is not large (for example, the total number of FPC strips 35 is eight or less or six or less), all the FPC strips 35 can be bound as a set by the binder 5, not by subset.

[0025] The FPC2 is a strip-shaped member that extends in a predetermined direction with a predetermined width W2, and has a first end 2a and a second end 2b opposite to the first end 2a in the extending direction (see FIG. 2). The FPC2 is typically a long strip-shaped member that is long in the predetermined direction described above, but is not limited to this. The FPC2 has high-frequency signal transmission paths 7 that are arranged in parallel in the width direction. Slits 21 are formed between the transmission paths 7 adjacent to each other in the width direction of the FPC2, thereby forming an FPC strip 35 in the FPC2.

[0026] The FPC strip 35 is a belt-like portion extending in the same direction as the FPC 2, and has flexibility similar to that of the FPC 2. Each FPC strip 35 is typically provided with a single-channel transmission path 7, but may also have multiple-channel transmission paths 7. Additionally or alternatively, wiring other than the transmission path of the high-frequency signal (power line, signal line, control line, test line, etc.) may also be provided. The width of each FPC strip 35 is approximately the same, but is not limited thereto. Making the width of the FPC strips 35 equal makes it easier to bind the FPC strips 35 with the binder 5. In this specification, except for paragraphs relating to or referring to either FIG. 21 or FIG. 22, the FPC strip 35 means a signal transmission strip provided with a transmission path of the high-frequency signal.

[0027] The slit 21 extends in the same direction as the extension direction of the FPC 2, and has a first slit end 21a closer to the first end 2a of the FPC 2 and a second slit end 21b closer to the second end 2b of the FPC 2. As a result, the FPC 2 has a first end 23a (not slitted) between its first end 2a and the first slit end 21a of the slit 21, and has a second end 23b (not slitted) between its second end 2b and the second slit end 21b of the slit 21. The first and second ends 23a, 23b are also joining portions where the respective FPC strips 35 are joined.

[0028] The FPC 2 and each FPC strip 35 include a dielectric layer 24, a signal line 25 formed on a first surface 24m of the dielectric layer 24, and a ground layer 27 formed on a second surface 24n of the dielectric layer 24, i.e., the transmission line 7 includes a microstrip line (see FIG. 3). As described above, a slit 21 is formed between the transmission lines 7, which enhances the insulation between the transmission lines 7 and enables bundling of the FPC strip 35. The signal line 25 may include a pair of signal lines 25a, 25b used as a transmission line for a differential signal. The signal lines 25a, 25b extend parallel to each other with a predetermined interval between them. The ground layer 27 may cover the second surface 24n of the dielectric layer 24 over the entire width of the FPC strip 35.

[0029] In some cases, the ground layers 27 of adjacent FPC strips 35 on the FPC 2 are not electrically connected. The width of the ground layers 27 is narrower than the width of the FPC strip 35, and the ground layers 27 are not cut by the slits 21. More specifically, a part of the second coating layer 29n is between the ground layers 27 and the slits 21. This enhances isolation between adjacent transmission paths 7 and reduces crosstalk. Note that, in the bundling portion 31 of the FPC 2, the transmission paths 7 are arranged in the stacking direction of the FPC strips 35, but in the first end 23a and the second end 23b of the FPC 2, the transmission paths 7 are arranged in the width direction of the FPC 2. Therefore, crosstalk can be suppressed even when the bundling tool 5 is used.

[0030] The FPC 2 and each FPC strip 35 may include at least a pair of ground lines 26 formed on both sides of the signal line 25 on the first surface 24m of the dielectric layer 24 so as to sandwich the signal line 25 therebetween, that is, the transmission line 7 includes a coplanar line in addition to the above-mentioned microstrip line (that is, the transmission line 7 can be said to be based on both the microstrip line and the coplanar line). The FPC 2 and each FPC strip 35 may further include at least a pair of through electrodes 28 that individually connect each of the at least pair of ground lines 26 to the ground layer 27. The signal line 25 is surrounded by a ground potential, providing sufficient EMI (Electro Magnetic Interference) countermeasures, and facilitating the transmission of high-frequency signals with low loss.

[0031] The ground line 26a extends in parallel to the signal line 25a at a predetermined distance, and similarly, the ground line 26b extends in parallel to the signal line 25b at a predetermined distance. The first ground line 26a is electrically connected to the ground layer 27 via a through electrode 28a. The second ground line 26b is electrically connected to the ground layer 27 via a through electrode 28b.

[0032] For one or more purposes (e.g., fire resistance, mechanical strength, and short circuit prevention of the FPC 2), the FPC 2 and each FPC strip 35 may further include a first covering layer 29m formed on the first surface 24m of the dielectric layer 24 to cover the signal line 25 (e.g., differential signal line) and a second covering layer 29n formed on the second surface 24n of the dielectric layer 24 to cover the ground layer 27. Either one or both may be omitted. The covering layer is made of, for example, polyimide, polyethylene terephthalate, or the like.

[0033] Contacts of the transmission path 7 (e.g., contacts of the signal line 25, the ground line 26, and the ground layer 27) are formed at the first and second ends 23a, 23b of the FPC 2 (see Figs. 2 and 4). For example, at the first and second ends 23a, 23b of the FPC 2, the signal line 25 and the ground line 26 are not covered by the first covering layer 29m, and the contacts are exposed. In the illustrated example, the contacts 25c, 25d of the signal lines 25a, 25b are sandwiched between the contacts 26c, 26d of the ground lines 26a, 26b.

[0034] In some cases, the FPC 2 is manufactured by a bump build-up method. In the bump build-up method, a large number of bumps are formed on a first surface of a first metal foil, and a dielectric layer (e.g., liquid crystal polymer) and a second metal foil are laminated in this order on the first surface of the first metal foil on which the bumps are formed. Then, the first metal foil, the dielectric layer, and the second metal foil are bonded together by heat pressing. In this laminate, the first metal foil and the second metal foil are electrically connected via the through electrodes derived from the bumps. The first metal foil is used as the ground layer 27, and the second metal foil is used as the signal line 25 and the ground line 26. The signal line and the ground line can be formed by patterning the metal foil (e.g., selective etching). The first and second metal foils are copper foils. In another case, the FPC 2 is manufactured by drilling holes in a double-sided copper-clad laminate (e.g., drilling holes using a drill or laser), copper plating the through holes (e.g., electroless plating), and etching. Other manufacturing methods can also be adopted.

[0035] The dielectric layer 24 has a predetermined relative dielectric constant and is made of, for example, liquid crystal polymer, polyimide, polyphenylene sulfide, polyethylene terephthalate, polyvinylidene chloride, polypropylene, etc. The signal line 25, the ground line 26, and the ground layer 27 are made of a metal such as copper (for example, copper foil such as rolled copper foil or electrolytic copper foil) or aluminum (for example, aluminum foil). The through electrode 28 is made of the same metal as the signal line 25, the ground line 26, and the ground layer 27.

[0036] The cable device 9 may further include a first plug member 6a fixed to the first end 23a of the FPC 2 and a second plug member 6b fixed to the second end 23b of the FPC 2 (see FIG. 2). The first plug member 6a has a main body 61 and an alignment protrusion 62 protruding from the main body 61, and the contacts of the transmission path 7 are arranged between the alignment protrusions 62. The second plug member 6b has a similar configuration to the first plug member 6a. The alignment protrusion 62 of the first plug member 6a is inserted into a slot (not shown) of the first connector 41, and the alignment between the contacts of the transmission path 7 of the FPC 2 and the contacts of the first connector 41 is ensured with high accuracy. The same explanation applies to the second plug member 6b.

[0037] In this embodiment, the cable device 9 has a spacer 80 inserted between the FPC strips 35 (signal transmission strips) in the stacking direction of the FPC strips 35 at one or more bundling points by at least one or more binders 5 (see FIG. 5). At the points where the FPC strips 35 are bound by the binder 5, the binder 5 applies a force to the stack of the FPC strips 35, narrowing the gap between the FPC strips 35. In this case, the effect of the parasitic capacitance generated between the FPC strips 35 cannot be ignored, and there is a risk that the transmission characteristics of the high-frequency signal by the FPC 2 will deteriorate. In the present disclosure, the use of the spacer 80 at least at the bundling points of the FPC strips 35 by the binder 5 can avoid or suppress the occurrence of such a problem.

[0038] The binder 5 may be a cable tie, a thread, a tape, a tubular member, etc., among which a tubular member is preferable. In some cases, the binder 5 may be a tubular member such as a spiral tube or a braided tube with slits that surrounds the laminate including the FPC strip 35 and the spacer 80. The use of a tubular member can reduce the risk of the binder 5 applying an excessively large force to the FPC strip 35. The spacer 80 may be compressed by an externally applied force, regardless of its material. When the spacer 80 is compressed, the interval of the FPC strip 35 decreases, and the effect of the parasitic capacitance increases. The use of a tubular binder 5 can avoid or suppress the manifestation of such a problem.

[0039] From the viewpoint of manufacturing or assembly efficiency of the cable device 9, a spacer 80 may be attached to the FPC 2. The spacer 80 may include one or more spacer strips 81 attached to at least the FPC strips 35 (signal transmission strips). The spacer strips 81 may be disposed between the FPC strips 35 in the stacking direction of the FPC strips 35 at one or more bundling points where the FPC strips 35 are bundled in a stacked state.

[0040] The spacer strip 81 may be a strip-shaped portion extending in a predetermined direction, similar to the FPC strip 35. When two or more spacer strips 81 are provided, the width of each spacer strip 81 may be substantially the same, but is not limited to this. By making the width of the spacer strip 81 equal to the width of the FPC strip 35, it is possible to avoid or suppress the spacer strip 81 from interfering with the binding of the FPC strip 35 by the binding device 5.

[0041] The number of spacer strips 81 is equal to or one less than the number of FPC strips 35. For example, when a total of two FPC strips 35 are provided on the FPC 2, the required number of spacer strips 81 to be inserted between the FPC strips 35 is one, but it is also possible to attach a spacer strip 81 to each FPC strip 35. By attaching the spacer strips 81 to the FPC strips 35 in a one-to-one relationship in this way, restrictions on the stacking order of the FPC strips 35 can be eliminated.

[0042] The length of the spacer strip 81 is preferably at least half, at least 70%, at least 80%, or at least 90% of the length of the slit 21 between the first and second slit ends 21a, 21b of the slit 21, and more preferably equal to or longer than that length. This makes it possible to more reliably secure a constant distance between the FPC strips 35 equivalent to the thickness of the spacer strip 81, thereby suppressing fluctuations in parasitic capacitance.

[0043] The spacer 80 and / or the spacer strip 81 may have a dielectric constant of 2 or less. Additionally or alternatively, the spacer 80 and / or the spacer strip 81 may have a thickness of 0.1 mm or more. The spacer 80 and / or the spacer strip 81 desirably has flexibility or deformability that does not inhibit the flexibility of the flexible cable, and is made of a soft porous material such as a nonwoven fabric. This makes it possible to meet both the conditions regarding the dielectric constant and the thickness easily and at low cost. Note that cloth or paper may also be used as the spacer 80 and / or the spacer strip 81.

[0044] The spacer 80 may be in the form of independent spacer strips 81 completely separated from each other as shown in FIG. 6, or in the form of spacer strips 81 connected to each other by connecting portions 82 as shown in FIG. 7. The connecting portions 82 are attached to the first end 23a or the second end 23b of the FPC 2, but may be provided at other locations. For example, the connecting portions 82 are provided so as to cross and connect the spacer strips 81 as shown in FIG. 8. In either form, when the FPC strip 35 is not bound by the binding tool 5, slits 85 are formed between the spacer strips 81. It is preferable to form the spacer strips 81 by bonding the spacer 80 to the FPC 2 and then cutting the spacer 80, thereby reducing the workload of bonding the spacer strips 81 to the FPC strips 35 individually.

[0045] The spacer 80 and / or the spacer strip 81 may be bonded to the FPC strip 35 via an adhesive. In this case, when the FPC strips 35 are stacked, the spacer strip 81 is automatically inserted between the FPC strips 35, improving the efficiency of manufacturing or assembling the cable device 9. Although the adhesive layer 89 is clearly shown as a layer in FIGS. 3 and 5, it is also possible to imagine an embodiment in which the adhesive layer 89 is not formed as a layer or is difficult to observe. For example, when the spacer strip 81 is a nonwoven fabric, the adhesive permeates the nonwoven fabric and the adhesive layer 89 is difficult to observe. Methods such as thermocompression bonding, heat welding, and ultrasonic welding without using an adhesive can also be adopted.

[0046] In some cases, single-layer FPC strips 35 and single-layer spacer strips 81 are alternately stacked in the stacking direction of the FPC strips 35 at the binding portion of the FPC strips 35 by the binder 5. This may be a result of laminating a single-layer spacer strip 81 to one side of the FPC strip 35. This suppresses an increase in the thickness of the laminate of the FPC strips 35 and the spacer strips 81 shown in FIG. 5. It is also possible to reduce the amount of adhesive layer used when the spacer strips 81 are bonded and fixed to the FPC strips 35 via an adhesive, and to reduce the effect of the dielectric constant of the adhesive layer on the transmission characteristics of high-frequency signals of the cable device 9.

[0047] The spacer 80 and / or the spacer strip 81 can be selectively attached (e.g., via an adhesive) to the FPC 2 or the FPC strip 35 on the second surface 24n side of the dielectric layer 24, which is the same as the ground layer 27. That is, the spacer 80 and / or the spacer strip 81 is attached to the FPC 2 or the FPC strip 35 only on the second surface 24n side of the dielectric layer 24, and is not attached to the FPC 2 or the FPC strip 35 on the first surface 24m side of the dielectric layer 24. When an adhesive is used, in a laminate in which the spacer 80 and / or the spacer strip 81 are attached to the FPC strip 35, the adhesive is formed / applied so as to overlap at least the ground layer 27 (e.g., overlap a partial region or the entire region of the ground layer 27) on the second surface 24n side of the dielectric layer 24, which is the same as the ground layer 27, and the adhesive is not formed / applied so as to overlap the signal line 25 on the first surface 24m side of the dielectric layer 24, which is the same as the signal line 25. In this configuration, it is possible to ensure the same high frequency signal transmission characteristics as in the case where the FPC strip 35 is not bound by the binder 5 as shown in Fig. 9. This point is supported by the evaluation results of a prototype based on the actual measurements shown in Figs. 10 to 13.

[0048] Fig. 10 is a diagram showing the variation in insertion loss with respect to frequency for the cable device 9 shown in Fig. 1, and Fig. 11 is a diagram showing the variation in return loss with respect to the frequency. Fig. 12 is a diagram showing the variation in insertion loss for a configuration in which the binder 5 shown in Fig. 9 is not used for binding, and Fig. 13 is a diagram showing the variation in return loss. It can be seen that, although the insertion loss and return loss increase when the binder 5 is used to bind the FPC strip 35, these are sufficiently suppressed by employing the spacer 80.

[0049] Figures 14 and 15 show the results when the FPC strip 35 is bound by the binding tool 5 without the use of the spacer 80 (Figure 14 relates to insertion loss, and Figure 15 relates to return loss). Comparing these figures with Figures 10 and 11, it can be seen that the use of the spacer 80 as disclosed herein is advantageous.

[0050] In some cases, as shown in Fig. 16, spacer strips 81 are attached to both sides of the FPC strip 35 so as to sandwich the FPC strip 35. In some cases, as shown in Fig. 17, no adhesive is formed on the first surface 24m of the dielectric layer 24, which is the same as the signal line 25, so that the adhesive near the signal line 25 does not overlap the signal line 25, thereby suppressing or avoiding a deterioration in the transmission characteristics of high-frequency signals in the cable device 9. Figs. 18 and 19 show the results when the laminate shown in Fig. 16 is bound by a binding tool 5 (Fig. 18 relates to insertion loss, and Fig. 19 relates to reflection loss). Depending on the selection of the material of the spacer, the spacer can be bound to the FPC by thermocompression bonding, thermowelding, ultrasonic welding, or the like without using an adhesive.

[0051] A method for manufacturing the cable device 9 will be described with reference to Fig. 20. This manufacturing method includes a step (S1) of manufacturing or preparing a flexible cable, a step (S2) of bundling a plurality of FPC strips in a stacked state using a bundling tool, and a step (S3) of inserting spacers between the FPC strips in the stacking direction of the FPC strips. This provides the same effect as described above. The step of preparing a flexible cable includes purchasing a flexible cable. Steps (S2) and (S3) can be performed manually by a person or by a machine.

[0052] If the spacer or spacer strip is previously attached to the FPC strip, step S3 is performed simultaneously with step S2. That is, the FPC strips 35 with the spacer or spacer strip are bundled in a stacked state with the binder 5, and at the same time, the spacer or spacer strip is inserted between the FPC strips 35. For this purpose, the above-mentioned manufacturing method may further include a step of attaching the spacer or spacer strip to the flexible cable. An adhesive may be used for this attachment, or thermocompression bonding, thermowelding, ultrasonic welding, etc. may be used. In some cases, the spacer and / or spacer strip is selectively attached to the ground side of the FPC.

[0053] To improve manufacturing or assembly efficiency, the above-mentioned manufacturing method may further include a step of cutting the spacer attached to the flexible cable at positions corresponding to the slits to form a plurality of spacer strips. The cutting of the spacer may be performed using a cutter, a rotary blade, or a die.

[0054] As can be seen from FIG. 21, it is not necessary that all the FPC strips 35 are signal transmission strips 35s including a transmission path for a high-frequency signal. The FPC strip 35 may include at least one dummy strip 35d in addition to the signal transmission strips 35s. The dummy strip 35d is a strip in which a transmission path for a high-frequency signal is not provided. Typically, the dummy strip 35d does not include a conductive layer (e.g., all of the signal line 25, the ground line 26, and the ground layer 27) and is made of a dielectric material (e.g., a laminate (e.g., a three-layer laminate) of the dielectric layer 24, the first covering layer 29m, and the second covering layer 29n). A spacer strip 81 may be attached to the dummy strip 35d, or may be omitted.

[0055] The dummy strip 35d can be arranged on the outermost layer in the stacking direction of the multiple FPC strips 35 at the point where the binder 5 is used (for example, on the top or bottom layer when the stacking direction of the FPC strips 35 coincides with the vertical direction) (see FIG. 21). With this configuration, the signal transmission strip can be separated from other external devices by the thickness of the dummy strip 35d, and the degree to which electromagnetic waves emitted from other external devices affect the transmission of high-frequency signals in the cable device 9 can be reduced. Note that the dummy strip 35d can also be arranged on both outermost layers in the stacking direction of the multiple FPC strips 35 at the point where the binder 5 is used (for example, on both the top and bottom layers when the stacking direction of the FPC strips 35 coincides with the vertical direction).

[0056] In a set of FPC strips 35 bound by the binder 5, the number of signal transmission strips 35s may be greater than the number of dummy strips 35d, thereby ensuring a required number of channels for signal transmission. Typically, in a set of FPC strips 35 bound by the binder 5, the number of dummy strips 35d is one or two and / or the number of signal transmission strips 35s is two, three, four or more. In some cases, a dummy strip 35d is adjacent to another FPC strip 35 (e.g., a signal transmission strip) at the binding point by the binder 5, but is not sandwiched between the other two FPC strips 35.

[0057] When the FPC strip 35 is not bound by the binder 5 (for example, in the state shown in FIG. 2), the dummy strip 35d can be arranged at one or both ends in the width direction of the FPC 2. With such an arrangement, the position of the dummy strip 35d can be identified without fail, and confusion between the dummy strip 35d and the signal transmission strip 35s is suppressed. In addition, the dummy strip 35d is easily arranged in the outermost layer. Alternatively or additionally, the dummy strip 35d is positioned near or toward the center in the width direction of the FPC 2. In this case, too, the dummy strip 35d is easily arranged in the outermost layer. In either case, a marker can be added to either the dummy strip 35d or the signal transmission strip 35s in order to distinguish between them (for example, the dummy strip 35d).

[0058] As shown in FIG. 22, dummy strips 35d and signal transmission strips 35s may be alternately stacked, and the dummy strips 35d may be used as spacers (specifically, spacer strips).

[0059] In light of the above disclosure, those skilled in the art may make various modifications to each embodiment and feature. Contacts may be formed in the FPC in various ways other than those shown. A configuration in which a spacer 80 is part of the binder 5 as shown in FIG. 23 is also envisioned and is within the scope of claim 1. In FIG. 23, the binder 5 has a plurality of fins 87 that function as spacers 80, and the FPC strip 35 can be inserted into the grooves between the fins 87. [Explanation of symbols]

[0060] 1: High frequency signal transmission device 2: FPC 2a: 1st end 2b: 2nd end 5: Binding tool 7: Transmission line 9: Cable device 21: Slit 24: Dielectric layer 25: Signal line 26: Ground line 27: Ground layer 28 :Through electrode 29m: 1st coating layer 29n: 2nd coating layer 35: FPC strip 35s: Signal transmission strip 35d: Dummy strip 80: Spacer 81: Spacer strip

Claims

1. a flexible cable having a plurality of cable strips formed according to one or more slits, the plurality of cable strips including two or more signal transmission strips each including at least one high-frequency signal transmission path, the high-frequency signal transmission path including one or more signal lines formed on a first surface of a dielectric layer and a ground layer formed on a second surface of the dielectric layer; one or more tie devices for binding the plurality of cable strips in a stacked state; a spacer disposed between the signal transmission strips in a stacking direction of the cable strip at least at one or more bundling locations using the one or more bundling devices, the spacer including one or more spacer strips laminated to the signal transmission strips; A cable device, wherein the spacer strip is not attached to the signal transmission strip via an adhesive on the same first surface side as the signal line, but is attached to the signal transmission strip via an adhesive on the same second surface side as the ground layer.

2. The cable device according to claim 1 , wherein the adhesive is formed so as to overlap at least the ground layer on the same side of the second surface as the ground layer.

3. the spacer includes two or more of the spacer strips; 3. The cable device according to claim 1, wherein single layers of the signal transmission strips and single layers of the spacer strips are alternately laminated in a lamination direction of the cable strip at the one or more bundling points.

4. 3. The cable device of claim 1, wherein the slit formed in the flexible cable has a first slit end near a first end of the flexible cable and a second slit end near a second end of the flexible cable, and the length of the spacer strip is equal to or greater than half the length of the slit between the first slit end and the second slit end.

5. The cable device according to claim 1 , wherein the spacer has a relative dielectric constant of 2 or less.

6. A cable device described in any one of claims 1 to 5, wherein the thickness of the spacer is 0.1 mm or more.

7. A cable device described in any one of claims 1 to 6, wherein the material of the spacer is non-woven fabric, cloth, or paper.

8. 8. The cable device according to claim 1, wherein each of the two or more signal transmission strips includes the dielectric layer, one or more differential signal lines as the one or more signal lines formed on a first surface of the dielectric layer, at least a pair of ground lines formed on both sides of the one or more differential signal lines on the first surface of the dielectric layer so as to sandwich the one or more differential signal lines, the ground layer, and at least a pair of through electrodes individually connecting each ground line of the at least pair of ground lines to the ground layer.

9. 9. The cable assembly according to claim 1, wherein the one or more ties are tubular members surrounding a stack including the plurality of cable strips and the one or more spacer strips.

10. The cable device according to claim 1 , wherein the plurality of cable strips are bundled by the bundling device for each subset of the plurality of cable strips.

11. a process for manufacturing or preparing a flexible cable having a plurality of cable strips formed according to one or more slits, the plurality of cable strips including two or more signal transmission strips each including at least one high frequency signal transmission path, the high frequency signal transmission path including one or more signal lines formed on a first surface of a dielectric layer and a ground layer formed on a second surface of the dielectric layer; applying a spacer to the flexible cable, the spacer including one or more spacer strips that are applied to the signal transmission strip; a step of bundling the plurality of cable strips in a stacked state with one or more bundling devices after the step of attaching a spacer to the flexible cable, the step including a step of stacking the cable strips at least at one or more bundling points with the one or more bundling devices and simultaneously arranging the spacer strips between the signal transmission strips in the stacking direction of the cable strips; A method for manufacturing a cable device, wherein the spacer strip is not attached to the signal transmission strip via an adhesive on the first surface side same as the signal line, but is attached to the signal transmission strip via an adhesive on the second surface side same as the ground layer.

12. The method for manufacturing a cable device according to claim 11, further comprising the step of cutting the spacer attached to the flexible cable at positions corresponding to the slits to form a plurality of spacer strips including the one or more spacer strips.

13. The manufacturing method according to claim 12 , wherein single layers of the signal transmission strips and single layers of the spacer strips are alternately laminated in a lamination direction of the cable strip at least at one or more bundling points by the one or more bundling devices.

14. A flexible cable having a plurality of cable strips formed according to one or more slits, the plurality of cable strips including two or more signal transmission strips each including at least one transmission path for a high frequency signal; one or more tie devices for binding the plurality of cable strips in a stacked state; a spacer disposed between the signal transmission strips in a stacking direction of the cable strip at least at one or more bundling points by the one or more bundling devices; the plurality of cable strips include at least one dummy strip having no high-frequency signal transmission path provided thereon in addition to the two or more signal transmission strips; A cable device, wherein the at least one dummy strip is arranged in the outermost layer in a stacking direction of the plurality of cable strips at least at one or more bundling locations using the one or more ties.

Images