High-frequency signal transmission device and method for electrically connecting a wiring board and a connector

Abstract

To solve a problem in which there is room to improve the high frequency signal transmission characteristics of the entire device including a connector in addition to a wiring board in a configuration in which a ground contact terminal of the connector contacts a ground contact pad of the wiring board.SOLUTION: When an FPC 2 is electrically connected to a connector 4, a contact portion b3 of an arm portion 42b of a ground contact terminal 46 of a connector 4 is at least partially in contact with the surface of a covering portion 58 of a ground contact pad P2 that covers a first through electrode 28 directly above the first through electrode 28, and alternatively, is positioned near the outer periphery of the covering portion 58 so as to come into contact with the ground contact pad P2.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present disclosure relates to a high-frequency signal transmission device and a method for electrically connecting a wiring board and a connector. [Background technology]

[0002] Patent Document 1 discloses an FPC for high-speed transmission with good impedance matching. In particular, a high-speed transmission path and a ground pattern are formed on one surface of a base. A first ground layer is laminated on the one surface of the base via a dielectric sheet. A second ground layer is laminated on the other surface of the base. The above-mentioned ground pattern is electrically connected to the first and second ground layers via through holes. In particular, FIG. 5 of the same document illustrates a cross-sectional configuration of an end portion of the FPC.

[0003] Patent Document 2 also discloses a configuration in which the ground lines on the front and back are electrically connected via contact holes (see Figures 1 and 2 in the document). Patent Document 3 discloses connecting a flexible cable and a connector using an adapter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-234500 A [Patent Document 2] Patent No. 5580994 [Patent Document 3] Patent No. 6721845 Summary of the Invention [Problem to be solved by the invention]

[0005] In a configuration in which the ground contact terminals of the connector abut against the ground contact pads of the wiring board, there is room for improving the high frequency signal transmission characteristics of the entire device, which includes the connector in addition to the wiring board. [Means for solving the problem]

[0006] A high-frequency signal transmission device according to one embodiment of the present disclosure includes a connector in which a contact terminal group, in which a plurality of contact terminals including a plurality of signal contact terminals and a plurality of ground contact terminals are regularly arranged, is supported by an insulator, and a wiring board in which a plurality of signal contact pads, a plurality of ground contact pads, and one or more ground layers are formed at at least one cable end, the one or more ground layers being electrically connected to the ground contact pads via at least one first through electrode that penetrates a dielectric layer of the wiring board. The ground contact terminal has an arm portion bent so as to locally abut against the ground contact pad at a contact portion. The contact portion of the arm portion is positioned so that (i) it at least partially abuts against a surface of a covering portion of the ground contact pad that covers the first through electrode directly above the first through electrode, or (ii) it abuts against the ground contact pad near the outer periphery of the covering portion when the wiring board is electrically connected to the connector.

[0007] In some embodiments, the contact terminal group includes a unit array in which two signal contact terminals are sandwiched between two ground contact terminals, and two adjacent ground contact terminals included in adjacent unit arrays in the width direction of the connector are positioned so that (i) the two adjacent ground contact terminals at least partially abut against a surface of the at least one common covering portion, or (ii) the two adjacent ground contact terminals abut against a ground contact pad near an outer periphery of the at least one common covering portion.

[0008] In any combination of the above-mentioned embodiments, ripples related to return loss and / or insertion loss are reduced in a high frequency band (eg, 20 to 25 GHz).

[0009] In any combination of the above-described aspects, when the wiring board is electrically connected to the connector, the first through electrode is positioned offset in a direction away from the free end of the arm portion compared to the contact portion of the arm portion.

[0010] In any combination of the above-mentioned forms, a plurality of second through electrodes that penetrate the dielectric layer to electrically connect a ground line formed in the same layer as the ground contact pad to a ground layer are arranged in the same row as the first through electrodes at a predetermined interval in the longitudinal direction of the wiring board, and the interval between the first through electrode and the second through electrode immediately adjacent to it is different from the predetermined interval of the plurality of second through electrodes.

[0011] In any combination of the above-described embodiments, the first through electrode has a cylindrical or truncated cone shape, and the arm portion extends in a tangential direction to an outer periphery of the covering portion.

[0012] In any combination of the above-mentioned forms, the multiple signal and ground contact pads are arranged in the width direction of the wiring board so as to form a unit array in which a pair of signal contact pads is sandwiched between two ground contact pads, and one ground contact pad is provided between adjacent pairs of signal contact pads in the width direction of the wiring board.

[0013] In any combination of the above-described embodiments, the wiring board has a plurality of differential signal lines, each consisting of two signal lines, and a plurality of ground lines formed on both sides of each differential signal line in the width direction of the wiring board so as to sandwich the differential signal lines, and one ground line is provided between adjacent differential signal lines in the width direction of the wiring board.

[0014] In any combination of the above-described aspects, one first through electrode is assigned to one ground contact pad for electrical connection with the ground layer.

[0015] In any combination of the above-mentioned embodiments, the one or more ground layers include a plurality of ground layers each extending in the longitudinal direction of the wiring board, and a plurality of ground contact pads are individually electrically connected to the plurality of ground layers via first through electrodes.

[0016] In any combination of the above-mentioned embodiments, the wiring board further includes a plurality of ground lines formed in the same layer as the plurality of ground contact pads, and each of the plurality of ground lines is electrically connected to each of the plurality of ground layers via a plurality of second penetrating electrodes that penetrate the dielectric layer.

[0017] In any combination of the above-mentioned aspects, the high-frequency signal transmission device further includes an adapter that supports the cable end of the wiring board and is mechanically coupled to the connector, and the cable end is positioned at a predetermined position in the connector by the mechanical coupling between the connector and the adapter.

[0018] A method for electrically connecting a connector and a wiring board according to another aspect of the present disclosure is a method for electrically connecting a connector and a wiring board, in which a contact terminal group, in which a plurality of contact terminals including a plurality of signal contact terminals and a plurality of ground contact terminals are regularly arranged, is supported by an insulator, the method comprising: At least one cable end of the wiring board is formed with a plurality of signal contact pads, a plurality of ground contact pads, and one or more ground layers, and the one or more ground layers are electrically connected to the ground contact pads via at least one first through electrode that penetrates the dielectric layer; The method includes a step of positioning a contact portion of the ground contact terminal so that (i) it at least partially abuts a surface of a covering portion of the ground contact pad that covers the first through electrode directly above the first through electrode, or (ii) it abuts the ground contact pad near an outer periphery of the covering portion.

[0019] In some embodiments, the contact terminal group includes a plurality of unit arrays each including two signal contact terminals sandwiched between two ground contact terminals, and two adjacent ground contact terminals included in adjacent unit arrays in the width direction of the connector are positioned so as to (i) at least partially abut on a surface of at least one common covering portion, or (ii) abut on a ground contact pad near an outer periphery of at least one common covering portion. Effect of the Invention

[0020] According to one aspect of the present disclosure, it is possible to improve the high-frequency signal transmission characteristics of the entire device including the connector in addition to the wiring board. [Brief description of the drawings]

[0021] [Figure 1] 1 is a schematic perspective view of a radio-frequency signal transmission device according to an embodiment of the present disclosure, and also illustrates a board that is communicatively connected via the radio-frequency signal transmission device. [Diagram 2] FIG. 2 is a schematic exploded perspective view of one cable end of the FPC detached from the connector. [Diagram 3] FIG. 3 is a perspective view of the opposite side of FIG. 2. [Figure 4] FIG. 2 is a schematic top view of an FPC with adapters, where each cable end of the FPC is supported by a respective adapter. [Diagram 5] 1 is a schematic partial top view of an FPC, in which a first through electrode is located at the center of the width of a ground contact pad, and a second through electrode is located at the center of the width of a ground line. [Figure 6] 6 is a schematic partial cross-sectional view of the FPC taken along the two-dot chain line VI-VI in FIG. 5. [Figure 7] FIG. 2 is a schematic side view of a connector. [Figure 8] 1 is a schematic top view of a connector, illustrating an opening of an insertion space into which an FPC is inserted. [Figure 9] FIG. 1 is a schematic diagram showing the state in which the FPC adapter is mechanically coupled to the connector and the FPC and connector are electrically connected, with a partial cross section showing the state in which the contact terminals of the connector abut against the contact pads of the FPC. [Figure 10] FIG. 1 is a partial schematic diagram showing the state in which the FPC adapter is mechanically coupled to the connector and the FPC and connector are electrically connected, with the signal and ground contact terminals of the connector abutting the signal and ground contact pads of the FPC, respectively. [Figure 11]13 is a simulation result showing the improvement in return loss. [Figure 12] 13 is a simulation result showing an improvement in insertion loss. [Figure 13] 13 is a simulation result showing an improvement in near-end crosstalk. [Figure 14] 1 is a simulation result showing improvement in far-end crosstalk. [Figure 15] FIG. 13 is a schematic diagram of another example in which two ground lines are formed between differential signal lines. [Figure 16] FIG. 13 is a schematic diagram of another example in which a change has been made to the ground layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Various embodiments and features of the present disclosure will be described below with reference to the drawings. Those skilled in the art can combine the embodiments and / or features without excessive explanation, and can 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 convenience of drawing. Each feature is not only effective for the high frequency signal transmission device and the related method disclosed in this specification, but is understood as a universal feature that is also applicable to various other high frequency signal transmission devices and related methods not disclosed in this specification.

[0023] 1 to 4, the high frequency signal transmission device 1 has an FPC (Flexible Printed Circuit) 2, adapters 3a and 3b (collectively, adapters 3), and connectors 4a and 4b (collectively, connectors 4). Cable ends 2a and 2b of the FPC 2 are electrically connected to the connectors 4a and 4b, respectively (for example, based on a mechanical connection between the adapters 3a and 3b and the connectors 4a and 4b). The connectors 4a and 4b are mounted on and electrically connected to different boards 9a and 9b or different board portions of the same board. In this manner, communication between boards is possible via the high frequency signal transmission device 1.

[0024] The FPC2 is a flexible cable, which is a non-limiting example of a wiring board. The FPC2 can have various shapes, and in addition to extending in one direction with a certain width, it can also extend in a meandering manner or extend in an S-shape or L-shape. The FPC2 can also have a width that changes in the direction in which it extends, and can include, for example, a narrow portion, a wide portion, a tapered portion, etc.

[0025] The FPC 2 has one or more transmission paths 7 for transmitting high-frequency signals between its cable ends 2a, 2b. Typically, a plurality of transmission paths 7 are arranged in the width direction of the FPC 2. As will be understood from the description below, a plurality of signal contact pads P1, a plurality of ground contact pads P2, and one or more ground layers 27 are formed at each of the cable ends 2a, 2b of the FPC 2 (see FIGS. 4 to 6). The one or more ground layers 27 are electrically connected to the ground contact pad P2 via at least one first through electrode 28 penetrating the dielectric layer 50. Note that slits may be formed between adjacent transmission paths 7 in the width direction of the FPC 2.

[0026] The adapters 3a and 3b are attached to the cable ends 2a and 2b of the FPC 2, respectively, to support the cable ends 2a and 2b. The adapter 3 has a body 31 shaped to receive the cable end of the FPC 2, a protrusion 32 protruding from the body 31 to support the cable end of the FPC 2, and a pair of alignment projections 33 provided on both sides of the protrusion 32 to sandwich it. The adapter 3 is shaped to be wide in the same direction as the FPC 2. When the adapter 3 is attached to the FPC 2, the signal and ground contact pads P1 and P2 of the FPC 2 are arranged between the alignment projections 33. The adapters 3a and 3b are mechanically connected to the connectors 4a and 4b, and the cable ends 2a and 2b of the FPC 2 are positioned at predetermined positions in the connectors 4a and 4b.

[0027] The connector 4 includes an insulator 41 shaped to have an insertion space 44 into which at least the cable ends 2a and 2b of the FPC 2 are inserted, an array (i.e., a group of contact terminals) of contact terminals 42 (signal and ground contact terminals may be collectively called contact terminals) supported by the insulator 41, and a fixing metal fitting 43 for fixing the connector 4 to the board 9. The insulator 41 is shaped to be wide in the same direction as the FPC 2. In the array of the contact terminals 42, the contact terminals 42 (specifically, the signal and ground contact terminals) are regularly arranged. More specifically, adjacent identical or different contact terminals 42 are arranged at the same or different pitches in the arrangement direction of the contact terminals 42 (typically, the width direction of the connector 4). The manner in which the insulator 41 supports the contact terminals 42 can be achieved by various methods such as insert molding, press-fitting, and adhesion. In addition to the cable ends 2a and 2b of the FPC 2, the protrusions 32 and alignment protrusions 33 of the adapter 3 are inserted into the insertion space 44 of the insulator 41. For this purpose, the insertion space 44 of the insulator 41 is appropriately shaped.

[0028] A locking protrusion 49 can be provided on the outer surface of the insulator 41 of the connector 4, and a locked portion 39 that is locked to the adapter 3 by the locking protrusion 49 can be provided (see FIG. 3). This makes it possible to prevent the adapter 3 from being unintentionally removed from the connector 4, and also improves the positional accuracy of the adapter 3 relative to the connector 4. The locking protrusion can also be provided on the adapter 3, and the locked portion can be provided on the connector 4. Two or more locking points for the locking protrusion and the locked portion can also be provided. The FPC 2 can also be directly connected to the connector 4 without using the adapter 3.

[0029] 4 and 5, a plurality of transmission paths 7 are arranged in the width direction of the FPC 2. The transmission path 7 includes a differential signal line 25 consisting of two signal lines 25a, 25b through which a differential signal is transmitted, and a pair of ground lines 26 formed on both sides of the differential signal line 25 so as to sandwich the differential signal line 25 in the width direction of the FPC 2. The differential signal line 25 (signal lines 25a, 25b) is formed between the cable end 2a and the cable end 2b. Similarly, the pair of ground lines 26 is formed between the cable end 2a and the cable end 2b.

[0030] An array of signal contact pads P1a, P1b (collectively, signal contact pad P1) and ground contact pads P2 is formed on cable ends 2a, 2b of the FPC2. The signal and ground contact pads P1, P2 can be arranged in the width direction of the FPC2 so that a pair of signal contact pads P1a, P1b forms a unit array PU sandwiched between two ground contact pads P2. The signal contact pads P1a, P1b are formed in the same layer as the signal lines 25a, 25b of the differential signal line 25 and connected thereto. The signal contact pads P1a, P1b have an area that is not covered by a first coverlay 53 described below for contact with a signal contact terminal. The ground contact pad P2 is formed in the same layer as the ground line 26 and connected thereto. The ground contact pad P2 has an area that is not covered by a first coverlay 53 described below for contact with a ground contact terminal. The signal contact pads can also be regarded as exposed parts of the signal lines, and the ground contact pads can also be regarded as exposed parts of the ground lines.

[0031] In some cases, one ground line 26 is provided between the differential signal lines 25 adjacent in the width direction of the FPC2. The differential signal lines 25 adjacent in the width direction of the FPC2 are electromagnetically coupled to a common ground line 26 formed therebetween. Similarly, one ground contact pad P2 is provided between a pair of signal contact pads P1a, P1b adjacent in the width direction of the FPC2. The pair of signal contact pads P1a, P1b adjacent in the width direction of the FPC2 are electromagnetically coupled to a common ground contact pad P2 formed therebetween. In the above-mentioned cases, the ground line 26 and / or the ground contact pad P2 can be formed wide, which facilitates the formation of a through electrode, which will be described later, in a more inexpensive manner.

[0032] 6, the FPC 2 has a dielectric layer 50 whose thickness is determined by a first surface 50p and a second surface 50q, a first wiring layer 51 formed on the first surface 50p of the dielectric layer 50, a second wiring layer 52 formed on the second surface 50q of the dielectric layer 50, a first coverlay 53 laminated on the first surface 50p of the dielectric layer 50 via the first wiring layer 51, a second coverlay 54 laminated on the second surface 50q of the dielectric layer 50 via the second wiring layer 52, and a reinforcing plate 55. Note that the reinforcing plate 55 is provided for assembly to the adapter 3, and is not formed over the entire length of the FPC 2.

[0033] The dielectric layer 50 is made of a material having a predetermined relative dielectric constant, for example, a liquid crystal polymer. The first wiring layer 51 may be a wiring layer in which a metal foil is patterned. The above-mentioned differential signal lines 25 and ground lines 26 are formed in the first wiring layer 51. The second wiring layer 52 may be a wiring layer in which a metal foil is patterned. In the second wiring layer 52, one or more ground layers 27 are formed, which are electrically connected to the ground contact pads P2 via first through electrodes 28 (also called bumps) that penetrate the dielectric layer 50.

[0034] As shown in FIGS. 5 and 6, the ground layer 27 is formed as a solid layer that covers the entire area of ​​the second wiring layer 52 except for the area immediately below the signal contact pad P1.

[0035] As shown in Fig. 5 and Fig. 6, the ground contact pad P2 and the ground layer 27 are electrically connected via the first through electrode 28, and the ground potential of the transmission path 7 is stabilized. Similarly, the ground line 26 and the ground layer 27 are electrically connected via a second through electrode 29 different from the first through electrode 28, and the ground potential of the transmission path 7 is stabilized. The high-frequency signal transmission characteristics are improved by stabilizing the ground potential. Note that the first through electrode 28 and the second through electrode 29 are made of the same arbitrary conductive material (for example, a metal such as copper or silver, or a conductive resin mixed with metal particles such as copper or silver), but are distinguished because the former is provided for the ground contact pad P2 and the latter is provided for the ground line 26. Needless to say, two or more first through electrodes 28 can be assigned to one ground contact pad P2.

[0036] A plurality of second through electrodes 29 penetrating the dielectric layer 50 may be arranged in the same row (or on the same straight line) as the first through electrodes 28 at predetermined intervals in the longitudinal direction of the FPC 2 to electrically connect the ground line 26 to the ground layer 27. As can be seen by referring to FIG. 5, the interval between the first through electrode 28 and the second through electrode 29 immediately adjacent thereto may be different from (e.g., less than) the predetermined interval between the second through electrodes 29. This can promote the intended alignment of the first through electrode 28 and the ground contact terminal 46 as described below. By allocating the first through electrode 28 to the ground contact pad P2, the occurrence of ripples is suppressed as described below regardless of the pitch of the second through electrodes 29.

[0037] 7 and 8, the connector 4 is further described. A plurality of signal contact terminals 45 and a plurality of ground contact terminals 46 are supported by the insulator 41 (for example, at a fixed or different arrangement pitch). Typically, the signal contact terminals 45 and the ground contact terminals 46 are provided so as to be able to individually contact the signal contact pads P1 and the ground contact pads P2 arranged on one side of the FPC 2, but other arrangements are also possible. For high-frequency signal transmission, in some cases, a unit array 6 in which two signal contact terminals 45a, 45b (collectively, signal contact terminals 45) are sandwiched between two ground contact terminals 46 is arranged in the width direction of the connector 4.

[0038] The connector 4 may have a constant or different (e.g., 2 or more) arrangement pitch for the contact terminals 42. In the former case, all the contact terminals 42 (all the signal and ground contact terminals 45, 46) are arranged at a constant pitch in the arrangement of the contact terminals 42 (satisfying D1=E1=F1 in FIG. 10). In the latter case, the pitch between directly adjacent signal contact terminals (F1 in FIG. 10), the pitch between directly adjacent ground contact terminals (D1 in FIG. 10), and the pitch between directly adjacent signal contact terminals and ground contact terminals are set to be different. The pitch is defined as the distance between the center lines of the contact terminals 42 in the arrangement direction of the contact terminals 42 (typically equal to the width direction of the connector 4) (the center lines are in a plane perpendicular to the arrangement direction).

[0039] The contact terminals 42 (signal contact terminals 45 and ground contact terminals 46) are typically metal plates bent at one or more locations, supported in a cantilever manner by the insulator 41 of the connector 4, and are elastically displaceable (see FIG. 9). When the adapter 3 is not mechanically connected to the connector 4, the contact terminals 42 are in an initial position. When the adapter 3 is mechanically connected to the connector 4, the contact terminals 42 are pushed by the FPC 2 and displaced.

[0040] The contact terminal 42 may have an arm portion bent so as to locally abut against the contact pad at a contact portion (see FIG. 9). In particular, the signal contact terminal 45 may have an arm portion bent so as to locally abut against the signal contact pad P1 at a contact portion. Similarly, the ground contact terminal 46 may have an arm portion bent so as to locally abut against the ground contact pad P2 at a contact portion b3.

[0041] More specifically, the contact terminal 42 may have a fixed portion 42a fixed to the insulator 41, an arm portion 42b extending from the fixed portion 42a toward the opening of the insertion space 44 of the insulator 41, and a connection portion 42c electrically connected (for example, by reflow soldering or the like) to a contact (not shown) on the substrate 9. The arm portion 42b has a bent shape so as to have a contact portion b3 that abuts against the signal or ground contact pads P1, P2 between the fixed portion 42a and the free end of the arm portion 42b. In detail, the arm portion 42b has a first inclined portion b1 and a second inclined portion b2, and the contact portion b3 is formed between them. The first inclined portion b1 extends obliquely from the fixed portion 42a. The second inclined portion b2 is a stub that extends obliquely in the opposite direction to the inclination direction of the first inclined portion b1. In this way, the contact portion b3 is formed in a convex shape between the first inclined portion b1 and the second inclined portion b2. The free end of the arm portion 42b is at one end of the second inclined portion b2 opposite the contact portion b3.

[0042] In this embodiment, when the FPC 2 is electrically connected to the connector 4, the contact portion b3 of the arm portion 42b of the ground contact terminal 46 is positioned so that it at least partially abuts against the surface of the covering portion 58 of the ground contact pad P2 covering the first through electrode 28 directly above the first through electrode 28, or abuts against the ground contact pad P2 near the outer periphery of the covering portion 58 (see FIG. 10). This makes it possible to improve the high-frequency signal transmission characteristics (see, for example, FIGS. 11 to 14). The distance (for example, the minimum distance) between the contact portion b3 and the outer periphery of the covering portion 58 when the contact portion b3 is located near the outer periphery of the covering portion 58 is a distance that improves the high-frequency signal transmission characteristics, specifically, a distance that reduces ripples related to return loss and / or insertion loss in the high-frequency band of 20 to 25 GHz. The covering portion 58 of the ground contact pad P2 described above is shown in FIG. 6 in addition to FIG. 10. The covering portion 58 is part of the ground contact pad P2, and therefore the circumference of the covering portion 58 is equal to or understood in the light of an imaginary surface (typically a cylindrical surface) that defines the extent of the covering portion 58.

[0043] When the FPC 2 is electrically connected to the connector 4, the first through electrode 28 can be positioned offset in a direction away from the free end of the arm portion 42b compared to the contact portion b3 of the arm portion 42b. In this case, it can be expected that the reduction of ripples related to return loss and / or insertion loss can be further promoted.

[0044] Narrowing the pitch of the contact terminals 42 may be advantageous for achieving the above-mentioned objective. In some cases, the arrangement pitch is within a range of 0.4 mm to 1.0 mm, and more preferably within a range of 0.5 mm to 0.8 mm. The gap between the contact portion and the outer periphery of the covering portion may be any value greater than 0 mm and equal to or less than 0.4 mm. Although even a small distance can act as a line for a high-frequency signal, a similar improvement in high-frequency signal transmission characteristics can be seen by making the distance 0.4 mm or less. In addition to or instead of narrowing the pitch of the contact terminals 42, it may also be advantageous to form the first through electrode 28 with a wide width or large diameter (note that an inexpensive method for forming a through electrode can also be adopted at the same time).

[0045] When the contact portion b3 of the arm portion 42b is positioned adjacent to the outer periphery of the covering portion 58 of the ground contact pad P2, it is assumed that the contact portion b3 does not come into contact with the outer periphery of the covering portion 58, and a slight gap is formed between the contact portion b3 and the outer periphery of the covering portion 58. The allowable dimension of the gap between the contact portion b3 and the outer periphery of the covering portion 58 is preferably an arbitrary value exceeding 0 mm and not exceeding 0.4 mm. It is also assumed that the positions of the contact portion of the ground contact terminal 46 and the covering portion 58 vary due to the influence of manufacturing errors, etc. For example, the contact portion of one ground contact terminal 46 may come into contact with the covering portion 58, and the contact portion of another ground contact terminal 46 may come into contact with the outer periphery of the covering portion 58, and the contact portion of the other ground contact terminal 46 may be positioned with a slight gap from the outer periphery of the covering portion 58.

[0046] When the FPC 2 is electrically connected to the connector 4, the arm portion 42b of the ground contact terminal 46 can extend in a tangential direction relative to the outer periphery of the covering portion 58 of the ground contact pad P2 that covers the first through electrode 28 directly above the first through electrode 28 (see FIG. 10). Typically, the extending direction of the arm portion 42b is equal to the insertion direction of the FPC 2 into the connector 4 or the longitudinal direction of the FPC 2.

[0047] Two adjacent ground contact terminals 46 included in unit arrays 6 adjacent in the width direction of the connector 4 are positioned so as to at least partially abut on the surface of at least one common covering portion 58, or to abut on the ground contact pad P2 near the outer periphery of at least one common covering portion 58 (see FIG. 10). In other words, a pair of immediately adjacent ground contact terminals 46 (i.e., the central GG pair of "GSSGGSSG") in the adjacent pairs of the GSSG array of the contact terminals 42 is positioned as described above with respect to the common covering portion 58 (or the common first through electrode 28). This makes it possible to improve the high-frequency signal transmission characteristics with a small number of first through electrodes 28, and promotes, for example, the adoption of an inexpensive method for forming through electrodes. Also, optimally, one first through electrode 28 is assigned to one ground contact pad P2 for electrical connection with the ground layer 27.

[0048] The first through electrode 28 and the second through electrode 29 are arranged in the same row (or on the same straight line) along the longitudinal direction of the FPC 2, and the contact portion b3 of the ground contact terminal 46 is not arranged directly above the first through electrode 28 (and the covering portion 58 of the ground contact pad P2). By forming the first through electrode 28 at the widthwise center of the ground contact pad P2, it becomes easier to form the second through electrode 29 at the widthwise center of the ground line 26, and the FPC 2 can be manufactured by a less expensive method in terms of the positional accuracy of the through electrodes in the width direction of the FPC 2.

[0049] When the first through electrode 28 has a cylindrical or truncated cone shape, the covering portion 58 has a circular outer periphery, and the arm portion 42b may extend in a tangential direction to the outer periphery. However, the first through electrode 28 may be formed to have a polygonal outer periphery such as a triangle, a rectangle, or a pentagon.

[0050] 10, the signal contact pads P1a, P1b may have a width varying portion 61 whose pad width varies as it extends in the longitudinal direction of the FPC 2. The width varying portion 61 is provided between a narrow portion 62 and a wide portion 63, and the pad width changes continuously between them.

[0051] In the simulation results shown in Figs. 11 to 14, the solid lines indicate the high-frequency signal transmission characteristics of the embodiment shown in Figs. 1 to 10, and the dashed lines indicate the high-frequency signal transmission characteristics of the comparative example without the first through electrode 28 shown in Fig. 10. As shown in Fig. 11, the return loss was improved. As shown in Fig. 12, the insertion loss was improved. As shown in Fig. 13, the near-end crosstalk was improved. As shown in Fig. 14, the far-end crosstalk was improved. In particular, as can be seen from Figs. 11 to 14, in the embodiment, ripples were suppressed in the vicinity of 20 to 25 GHz.

[0052] The FPC2 can be 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 copper 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. Thereafter, the first metal foil, the dielectric layer, and the second metal foil are adhered to each other by a heat press. In this laminate, the first metal foil and the second metal foil are electrically connected via the through electrodes derived from the bumps. One of the first and second metal foils is used as the first wiring layer 51, and the other is used as the second wiring layer 52. The signal lines, ground lines, ground layers, and contact pads can be formed by patterning the metal foil (e.g., selective etching). Copper foil can be used as the metal foil. Other manufacturing methods can also be adopted for the FPC2.

[0053] The insulator 41 of the connector 4 can be manufactured from a plastic material using an injection molding machine. The contact terminals 42 can be manufactured by processing (punching, bending) a metal plate. The contact terminals 42 can be attached and supported on the insulator 41 by a method such as insert molding, press-fitting, or adhesion.

[0054] 10, one ground line 26 is formed between the differential signal lines 25, and one ground contact pad P2 is provided between the pair of signal contact pads P1a, P1b, but this is not limited to the above. As shown in FIG 15, two ground lines 26 may be formed between the differential signal lines 25, and two ground contact pads P2 may be provided between the pair of signal contact pads P1a, P1b. In other words, one ground contact pad P2 (or ground line 26) may be assigned to one ground contact terminal 46.

[0055] In FIG. 10, the arm portion 42b of the ground contact terminal 46 extends in a tangential direction relative to the outer periphery of the ground contact pad P2 without overlapping the covering portion 58 of the ground contact pad P2, but this is not limited thereto. As shown in FIG. 15, the arm portion 42b of the ground contact terminal 46 can extend in a tangential direction relative to the outer periphery of the ground contact pad P2 while overlapping a part of the covering portion 58 of the ground contact pad P2. In the case of FIG. 10, the arm portion 42b and the contact portion b3 are not disposed directly above the first through electrode 28. In the case of FIG. 15, the arm portion 42b and the contact portion b3 are disposed partially directly above the first through electrode 28. By making the arm portion 42b of the ground contact terminal 46 wider, the arm portion 42b can overlap the entire covering portion 58 directly above the first through electrode 28.

[0056] In the embodiment shown in FIG. 16, the transmission line 7 is configured as a combination of a differential coplanar line and a microstrip line, and the ground layer 27 can be formed to face the transmission line 7 except for the area directly below the contact pad P1. Typically, a plurality of ground layers 27 are formed in the second wiring layer 52, and the number of the ground layers 27 is equal to the number of the transmission lines 7. By electrically connecting the ground line 26 and the ground contact pad P2 corresponding to each transmission line to the ground layer 27, the ground potential can be divided or non-commonized between the transmission lines 7 of the FPC 2, and the high-frequency signal transmission characteristics can be improved (for example, crosstalk is reduced). Also, in such an embodiment, it is expected that the same effect as described above can be obtained by setting the alignment of the first through electrode 28 and the ground contact terminal 46 as described above.

[0057] In light of the above teachings, those skilled in the art can make various modifications to each embodiment and each feature. The wiring board does not need to be flexible and should not be limited to a flexible cable. For example, the various features disclosed in this application can be applied to a wiring board of a card edge connector. The number of ground contact terminals provided between a signal contact terminal pair for differential signal transmission is not limited to two, and may be one. The same effect can be expected even if the adapter is omitted from the connector. [Explanation of symbols]

[0058] 1: High frequency signal transmission device 2: FPC 2a: Cable end 2b: Cable end 3: Adapter 4: Connector 25: Differential signal line 25a: Signal line 25b: Signal line 26: Ground line 27: Ground layer 28: 1st through electrode 29: 2nd through electrode 41: Insulator 42: Contact terminal 45: Signal contact terminal 46: Ground contact terminal b3: Contact part 50: Dielectric layer 58: Covering part P1: Signal contact pad P2: Ground contact pad

Claims

1. a connector in which a contact terminal group, in which a plurality of contact terminals including a plurality of signal contact terminals and a plurality of ground contact terminals are regularly arranged, is supported by an insulator; a wiring board having a plurality of signal contact pads, a plurality of ground contact pads, and one or more ground layers formed at at least one cable end, the one or more ground layers being electrically connected to the ground contact pads via at least one first through electrode penetrating a dielectric layer of the wiring board; the ground contact terminal has an arm portion bent so as to locally abut against the ground contact pad at a contact portion; the contact portion of the arm portion is positioned so as to at least partially abut directly above the first through electrode against a surface of a covering portion of the ground contact pad that covers the first through electrode directly above the first through electrode when the wiring board is electrically connected to the connector; the contact terminal group includes a plurality of unit arrays, each of which is composed of a total of four contact terminals, with two of the signal contact terminals sandwiched between two of the ground contact terminals; A high-frequency signal transmission device, wherein two adjacent ground contact terminals included in adjacent unit arrays in the width direction of the connector are each positioned so as to at least partially abut a surface of at least one common covering portion.

2. 2. The high frequency signal transmission device according to claim 1, wherein ripples associated with return loss and / or insertion loss are reduced in the high frequency band.

3. 2. The high-frequency signal transmission device according to claim 1, wherein when the wiring board is electrically connected to the connector, the first through electrode is positioned offset in a direction away from the free end of the arm portion compared to the contact portion of the arm portion.

4. a plurality of second through electrodes penetrating the dielectric layer in order to electrically connect a ground line formed in the same layer as the ground contact pad to the ground layer, the second through electrodes being arranged in the same row as the first through electrodes at predetermined intervals in the longitudinal direction of the wiring board; 2 . The high frequency signal transmission device according to claim 1 , wherein a distance between the first through electrode and the second through electrode immediately adjacent thereto is different from the predetermined distance between the plurality of second through electrodes.

5. The high frequency signal transmission device according to claim 1 , wherein the first through electrode has a cylindrical or truncated cone shape, and the arm portion extends in a tangential direction to an outer periphery of the covering portion.

6. 2. The high-frequency signal transmission device of claim 1, wherein the plurality of signal and ground contact pads are arranged in the width direction of the wiring board so that a pair of the signal contact pads forms a unit array sandwiched between two of the ground contact pads, and one of the ground contact pads is provided between pairs of the signal contact pads adjacent to each other in the width direction of the wiring board.

7. 2. The high-frequency signal transmission device according to claim 1, wherein the wiring board has a plurality of differential signal lines, each consisting of two signal lines, and a plurality of ground lines formed on both sides of each differential signal line in a width direction of the wiring board so as to sandwich the differential signal lines, and one ground line is provided between adjacent differential signal lines in the width direction of the wiring board.

8. 2. The high frequency signal transmission device according to claim 1, wherein one of the first through electrodes is assigned to one of the ground contact pads for electrical connection with the ground layer.

9. 2. The high-frequency signal transmission device according to claim 1, wherein the one or more ground layers include a plurality of ground layers each extending in a longitudinal direction of the wiring board, and the plurality of ground contact pads are individually electrically connected to the plurality of ground layers via the first through electrodes.

10. 10. The high-frequency signal transmission device according to claim 9, wherein the wiring board further includes a plurality of ground lines formed in the same layer as the plurality of ground contact pads, and each of the ground lines of the plurality of ground lines is electrically connected to each of the plurality of ground layers via a plurality of second through electrodes that penetrate the dielectric layer.

11. 2. The high-frequency signal transmission device according to claim 1, further comprising an adapter that supports the cable end of the wiring board and is mechanically connected to the connector, and the cable end is positioned at a predetermined position in the connector by the mechanical connection between the connector and the adapter.

12. A method for electrically connecting a connector to a wiring board, the connector including a contact terminal group, in which a plurality of contact terminals including a plurality of signal contact terminals and a plurality of ground contact terminals are regularly arranged, and the contact terminal group is supported by an insulator, the method comprising the steps of: At least one cable end of the wiring board is formed with a plurality of signal contact pads, a plurality of ground contact pads, and one or more ground layers, and the one or more ground layers are electrically connected to the ground contact pads via at least one first through electrode that penetrates a dielectric layer; the method includes a step of positioning a contact portion of the ground contact terminal so as to at least partially abut directly above the first through electrode against a surface of a covering portion of the ground contact pad that covers the first through electrode directly above the first through electrode; the contact terminal group includes a plurality of unit arrays, each of which is composed of a total of four contact terminals, with two of the signal contact terminals sandwiched between two of the ground contact terminals; A method for electrically connecting a wiring board and a connector, wherein two adjacent ground contact terminals included in adjacent unit arrays in the width direction of the connector are each positioned so as to at least partially abut the surface of at least one common covering portion.

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