JP4998741B2 - Adapter structure, high-frequency cable body and wiring board connector - Google Patents

Description

  The present invention relates to an adapter structure for connecting a high-frequency cable to various wiring boards, a high-frequency cable body provided with the adapter structure, and a wiring board connector.

  In recent years, transmission and reception of signals between boards and wiring boards in various electronic devices such as LCD TVs, plasma displays, Blu-ray HDD recorders, servers, copiers, printers, and multifunction devices with image scanner functions, High speed transmission is required. As a response to such a demand for high-speed transmission, there is a high-frequency cable, for example, a coaxial cable, in which an outer conductor is provided around a round central conductor with a dielectric layer interposed therebetween.

  As a connector structure for connecting the coaxial cable to a substrate or the like, for example, as disclosed in Patent Document 1, there is one using a plug and a receptacle that can be inserted and removed from each other. That is, by connecting the receptacle to the substrate or the like with solder or the like and connecting the electric wire to the plug with solder or the like, the coaxial cable can be electrically connected to or removed from the substrate or the like.

JP-A-7-73932

  However, in the case of the above structure, there is a problem that the number of parts increases for both the plug and the receptacle, resulting in a very high cost.

  An object of the present invention is to provide a low-cost adapter structure that can maintain impedance matching by being used supplementarily in a connection portion of a high-frequency cable, and a high-frequency cable body and a wiring board connection body provided with the adapter structure.

In the adapter structure of the present invention, the first line conductor connected to the center conductor of the high-frequency cable is provided on the first surface of the flat dielectric layer, and the second line conductor connected to the wiring of the connected wiring board on the second surface. On the other hand, a first ground plane facing the first line conductor is provided on the second surface with a flat dielectric layer sandwiched therebetween.
Examples of the high-frequency cable include various flat cables and multi-core coaxial cables.

  Thereby, the microstrip line is constituted by the first line conductor and the first ground plane in the adapter structure. Therefore, the high frequency signal sent from the center conductor of the high frequency cable can be transmitted to the second line conductor while maintaining impedance matching.

  Further, in the connected wiring (mother board), if a generally provided ground plane of the mother board is used for the high-frequency wiring board, the second line conductor and the ground plane of the mother board can also be used. It is possible to configure a strip line. Therefore, in the adapter structure and the two microstrip lines provided between the adapter structure and the mother board, the materials and thicknesses of the first and second line conductors, the flat dielectric layer, and the dielectric layer of the mother board are appropriately designed. By doing so, matching of the impedance of the high-frequency cable, the impedance of the adapter structure, and the impedance of the mother board can be maintained, and signal transmission with low noise can be performed. In addition, since the adapter structure is a very simple structure, the cost can be reduced.

  Even if the high-frequency cable is a flat cable using a center conductor with a round cross section or a multi-core coaxial cable, the center conductor can be easily wired in the same way as a flexible printed wiring board with a flat conductor cross section. An inexpensive transmission line that can be connected to the wiring of the board and has excellent transmission characteristics can be configured.

  Moreover, since the second line conductor of such an adapter structure can be easily connected to the wiring of the mother board by ACF, ACP, NCF, NCP, etc., a flexible printed wiring board, a rigid printed wiring board, etc. As an adapter for connecting the two, it becomes inexpensive and highly usable.

  By further including a second ground plane facing the second line conductor on the first surface of the flat dielectric layer, only between the first line conductor and the first ground plane and in the second line conductor only in the adapter structure. A microstrip line can be formed between the second ground planes, and impedance matching can be maintained regardless of whether or not the ground plane is provided on the mother board.

  The high-frequency cable body formed by attaching the adapter structure to the high-frequency cable is a high-frequency cable that can be easily connected to various wiring boards, and the second line conductor in the adapter structure of the high-frequency cable can be connected to various connection members, for example, By connecting to the wiring of the mother board via the above-mentioned ACF, ACP, NCF, NCP, a wiring board connector is formed.

  According to the adapter structure, high-frequency cable body, or wiring board connector of the present invention, it is possible to provide an adapter structure, a high-frequency cable body, and a connection structure that are easy to match impedance and are low in cost.

(Embodiment)
-Adapter structure-
1A and 1B are a top view and a bottom view, respectively, of the adapter A according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view of the adapter A taken along the line II-II shown in FIG.
As shown in FIGS. 1 and 2, the adapter 10 includes a flat dielectric layer 11, a first line conductor 12 formed on the upper surface, which is the first surface of the flat dielectric layer 11, and a flat dielectric. The second line conductor 14 formed on the lower surface, which is the second surface of the body layer 11, and the signal line that penetrates the dielectric layer 11 and electrically connects the first line conductor 12 and the second line conductor 14. The through-hole conductor 13, the first ground plane 18 formed on the lower surface of the flat dielectric layer 11, the second ground plane 15 formed on the upper surface of the flat dielectric layer 11, and the flat dielectric layer 11 and a grounding through-hole conductor 16 that electrically connects the first ground plane 18 and the second ground plane 15.

As shown in FIG. 1A, the second ground plane 15 includes a base end portion 15a to which a high-frequency cable described later is connected, and side portions 15b positioned on both sides of the region where the first line conductor 12 is formed. have.
On the other hand, as shown in FIG. 1B, the first ground plane 18 includes a main portion 18a formed to face the base end portion 15a of the first ground plane 15 and the first line conductor 12, and a second portion. And side portions 18 b formed on both sides of the line conductor 14.

  Then, between the base end portion 15 a of the first ground plane 15 and the main portion 18 a of the second ground plane 18, and between the side portion 15 b of the first ground plane 15 and the side portion 18 b of the second ground plane 18. Each has a plurality of grounding through-hole conductors 16 formed therein. In this way, by connecting the upper and lower ground planes with a large number of through-hole conductors 16 in a wide area, a relatively large amount of high-frequency current can flow with low resistance.

In particular, the main portion 18a of the first ground plane 18 faces the first line conductor 12 with the flat dielectric layer 11 in between, so that the main portion 18a and the first line conductor 12
A microstrip line is configured.
On the other hand, the second ground plane 15 does not exist in the region facing the second line conductor 14 on the upper surface of the flat dielectric layer 11.

Each member of the adapter 10 of the present embodiment has the following materials and dimensions. However, this is an example, and the adapter A of the present invention is not limited to the following materials.
The flat dielectric layer 11 is made of a resin such as PI resin (polyimide resin) and has a thickness of about 25 μm to 300 μm. The first line conductor 12 and the second line conductor 14 are formed using a metal foil such as a copper foil having a width of 0.10 mm to 0.20 mm and a thickness of about 10 μm to 30 μm. The first and second ground planes 18 and 15 are formed using a metal foil such as a copper foil having a thickness of about 10 μm to 30 μm. The adapter 10 as a whole has a thickness of about 0.05 mm to 0.4 mm, a width of about 10 mm to 20 mm, and a length of about 3 mm to 10 mm.

  FIG. 3 is a longitudinal cross-sectional view of wiring board connector B according to Embodiment 1 in which high-frequency cable 20, adapter 10, and PWB (rigid printed wiring board) as a mother board are connected. FIG. 3 shows a cross-sectional structure corresponding to the II-II line shown in FIG. 1, and the cross-sectional structure of the high-frequency cable 20 in the direction orthogonal to the II-II line is shown above FIG.

In the structure shown in FIG. 3, a high-frequency cable (in this embodiment, a multi-core micro-coaxial line) 20 is formed by connecting a plurality of cable lines (micro-fine coaxial lines) 21 in parallel. Each cable line 21 is formed around a central conductor 22 made of a stranded wire and an intermediate insulator (dielectric layer) 23 around the central conductor 22, and covers an outer conductor 24 that serves as a ground, and the entire members. And the outer skin 26 (refer to the upper enlarged sectional view of FIG. 3). The tip of the center conductor 22 is exposed. Further, the intermediate insulator and the outer conductor 24 are also exposed stepwise.
The cable wire 21 made of a fine coaxial line is also provided with an outer conductor 24 around the center conductor 22 with the intermediate insulator 23 interposed therebetween, so that a microstrip line is formed. In addition, by appropriately designing the material and thickness of the intermediate insulator (dielectric layer) 23, the impedance can be adjusted so as to minimize the attenuation factor.

  Furthermore, a grounding member 25 (ground bar) that connects the exposed portions of the outer conductor 24 in common is provided. The grounding member 25 has an upper grounding member 25a and a lower grounding member 25b joined to each outer conductor 24 by soldering.

  As the cable wire (extra-coaxial wire) 21, for example, an ultra-fine wire (AWG (American Wire Gauge) 40-46) is used. Therefore, the center conductor 22 disposed at the center of the cable wire 21 is a stranded wire in which six copper wires are twisted, although not shown.

  The center conductor 21 of the high-frequency cable 10 is joined to the first line conductor 12 of the adapter 10 by solder or the like, and the lower ground member 25b of the high-frequency cable 10 is soldered to the base end portion 15a of the second ground plane 15. It is joined by etc. The high frequency cable 20 and the adapter 10 constitute a high frequency cable body A. Further, the high-frequency cable body A and the PWB 30 constitute a wiring board connector B.

The PWB 30 which is a mother substrate includes a rigid substrate 31 which is a dielectric substrate, wirings 32 formed on the main surface (upper surface) of the rigid substrate 31, and a main ground plane 38 formed on the back surface of the rigid substrate 31. It has. The wiring 32 of the PWB 30 and the second line conductor 14 of the adapter 10 are electrically connected by an ACF 34 (an anisotropic conductive adhesive).
Note that a connecting member such as ACP, NCF, or NCP may be used instead of the ACF 34.
The mother board is not limited to PWB, and other wiring boards such as an FPC (flexible printed wiring board) can also be used.

According to the adapter 10 of the present embodiment, a microstrip line in which the first line conductor 12 is arranged above the first ground plane 18 with the flat dielectric layer 11 interposed therebetween is configured.
The microstrip line has predetermined impedance characteristics according to the width and thickness of the first line conductor 12, the thickness and relative dielectric constant of the flat dielectric layer 11, and the like. That is, desired impedance characteristics can be obtained by appropriately designing the above elements. Accordingly, impedance matching with the connected high-frequency cable 20 is achieved, and a high-frequency signal is transmitted from the high-frequency cable 20 to the second line conductor 14 with high efficiency, that is, with low noise (low attenuation factor). Yes.

On the other hand, a ground plane facing the second line conductor 14 is not provided on the upper surface of the flat dielectric layer 11 of the adapter 10.
However, in the wiring board connector B, the main ground plane 38 of the PWB 30 faces the second line conductor 14 of the adapter 10 with the rigid substrate 31 that is a dielectric layer interposed therebetween. That is, the second line conductor 14, the rigid substrate 31 and the main ground plane 38 also constitute a microstrip line.
Note that in the entire PWB 30, the wiring 32, the rigid substrate 31, and the ground plane 38 constitute a microstrip line.

Therefore, the high-frequency cable 20 passes through the first line conductor 12 and the second line conductor 14 of the adapter 10, the wiring 32 of the PWB 30 that is the mother board, and various electronic components connected to the wiring. The signal is transmitted with high efficiency, that is, with low noise (low loss).
Generally, since a main ground plane is provided in a high-frequency PWB, a direct electrical connection between the second line conductor 14 and the wiring 32 by the ACF 34 is performed by the double-sided circuit type adapter 10 according to the present embodiment. Thus, a high-frequency signal can be transmitted to the mother board with low noise.

  FIGS. 10A to 10C are diagrams illustrating simulations of noise characteristics between the wiring board connector B of the present embodiment and other wiring board connectors.

  As shown in FIG. 7, the simulation 1 shown in FIG. 10A is calculated using a wiring board connection body in which the center conductor 22 of the high frequency cable is joined to the wiring 32 of the PWB 31 by direct soldering. In the structure of this wiring board connector, since the microstrip line is constituted by the main ground plane 38 of the PWB, the rigid board 31, the wiring 32 and the central conductor 22, the impedance matching of the high frequency signal is maintained. Noise is extremely small. However, in this structure, since it is necessary to secure a space for soldering the central conductor 22 and the wiring 32 on the PWB, restrictions on the design of the PWB are severe, and the practical value of the high-frequency cable body is Low.

  In simulation 2 shown in FIG. 10B, as shown in FIG. 8, the first and second line conductors 12 and 14 are formed on the upper and lower surfaces of the flat dielectric layer 11, respectively. The calculation is performed using a wiring board connector in which an unformed adapter is used and a PWB without a main ground plane is disposed on the back surface of the rigid board 31. In the structure of this wiring board connection body, the ground plane is not present in any of the first and second line conductors 12 and 14, and the microstrip line is not configured, so that impedance matching of the high frequency signal is not maintained. There is a lot of noise.

The simulation 3 shown in FIG. 10C is calculated using the wiring board connector B according to the first embodiment. In the wiring board connector B of the present embodiment, as described above, since the microstrip line is configured for both the first and second line conductors 12 and 14, low noise substantially comparable to the simulation 1 is achieved. The characteristics are realized.
That is, according to the wiring board connector B according to the first embodiment, the connection member such as ACF, ACP, NCF, or NCP can be used by connecting the adapter 10 to the high-frequency cable 20, so that the work space is small. A connectorless connection with the mother board is possible. And since it is not necessary to use a connector, low profile is also realized.

  As described above, the high-frequency cable body A according to the first embodiment performs connectorless connection with the mother board in a narrow work space by using the general-purpose high-frequency mother board provided with the main ground plane in combination. Can be practically valuable.

(Embodiment 2)
4A and 4B are a top view and a bottom view, respectively, of the adapter A according to Embodiment 2 of the present invention. FIG. 5 is a cross-sectional view of the adapter A taken along the line VV shown in FIG. FIG. 6 is a longitudinal cross-sectional view of a wiring board connector B according to Embodiment 2 in which the high-frequency cable 20, the adapter 10, and a PWB (rigid printed wiring board) as a mother board are connected.

In the present embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only members different from those in the first embodiment will be described.
As shown in FIGS. 4A and 5, in the present embodiment, the main surface of the second ground plane 15 is also formed in the region facing the second line conductor 14 on the upper surface of the flat dielectric layer 11. A portion 15d is formed. That is, the second line conductor 14, the flat dielectric layer 11, and the main portion 15 a of the second ground plane 15 constitute a microstrip line.

  Moreover, as shown in FIG. 6, the main ground plane is not provided in PWB30 of the wiring board connector B in this Embodiment. However, as in the first embodiment, a main ground plane may be provided on the back surface of the rigid substrate 31.

  According to the present embodiment, since the microstrip line is configured for both the first and second line conductors 12 and 14 of the adapter 10, whether or not the main ground plane is provided on the mother board is determined. Regardless of this, impedance matching of high-frequency signals can be achieved within the high-frequency cable body A.

  However, since the main portion 15d of the second ground plane 15 is present in the adapter 10, when the high-frequency cable body A is connected to the wiring 32 of the mother board such as the PWB 30, the second line conductor 14 that is generally visually observed Positioning with the wiring 32 becomes difficult. In that respect, the structure of the adapter 10, the high-frequency cable body A, and the wiring board connector B of the first embodiment is preferable.

(Other embodiments)
In the first and second embodiments, the multi-core micro-coaxial wire 20 is used as the high-frequency cable 20, but the high-frequency cable 20 of the present invention is not limited to the multi-core micro-coaxial wire 20, and other In general, a multi-core coaxial cable, a flat cable, a flexible flat cable, or the like that transmits a high-frequency signal can be used.

FIG. 9 is a longitudinal sectional view showing an example of a flat cable that can be used as the high-frequency cable of the present invention.
As shown in FIG. 9, the flat cable includes a shield 27 that covers the periphery of the plurality of central conductors 42 with the dielectric layer 41 interposed therebetween, a drain line 45 that extends while being in contact with the shield 47, and the shield 47 and the drain line 45. And an exterior film 46 to be coated.

The center conductor 42 is arranged in order from the left in the figure with a pitch of about 0.4 mm to 0.6 mm, and a first signal line 42p and a second signal line 42n through which differential signals are transmitted, respectively. Including. The three central conductors of the ground line 42g, the first signal line 42p, and the second signal line 42n are alternately repeated as one group, and the ground line 42g is disposed at the final end. That is, the first signal line 42p and the second signal line 42n are sandwiched between the ground lines 42g on both sides, thereby eliminating the crosstalk between the first signal line 42p and the second signal line 42n.
In addition, the cross-sectional shape of the center conductor 42 does not necessarily need to be a round shape, and may be a flat shape.

  Such a flat cable also has a structure in which the central conductor 42 (line) and the shield 27 face each other with the dielectric layer 41 interposed therebetween, and constitutes a microstrip line. Then, by appropriately designing the material and diameter of the center conductor 42 and the material and thickness of the dielectric layer 20, the impedance can be adjusted so that the attenuation factor is minimized.

  Although not shown, when such a flat cable is used, the first line conductor 12 and the second line conductor 14 are connected to a drain line of the flat cable and a ground line for preventing interference. And a first signal line and a second signal line through which differential signals are transmitted. The drain wiring is electrically connected to the first or second land planes 18 and 15. The three wirings of the ground wiring, the first signal wiring, and the second signal wiring are alternately and repeatedly arranged as one group.

  Even when such a flat cable is used as a high-frequency cable, the same effect as in the first or second embodiment can be obtained.

  In each of the above embodiments, the flat dielectric layer 11 is not limited to the PI resin in the above embodiments. Since the insulator is also a dielectric, various insulating materials such as other resins and inorganic insulating materials can be used.

  The structure of the embodiment of the present invention disclosed above is merely an example, and the scope of the present invention is not limited to the scope of these descriptions. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  The present invention can be used for signal transmission in electronic devices such as a mobile phone, a camera such as a digital camera and a video camera, a portable audio player, a portable DVD player, and a portable notebook computer.

(A), (b) is the top view and bottom view of the adapter which concern on Embodiment 1 of this invention in order. It is sectional drawing of the adapter in the II-II line | wire shown to Fig.1 (a). It is a longitudinal cross-sectional view of the wiring board connector which concerns on Embodiment 1 formed by connecting a high frequency cable, an adapter, and PWB. (A), (b) is the top view and bottom view of the adapter which concern on Embodiment 2 of this invention in order. It is sectional drawing of the adapter in the II-II line | wire shown to Fig.4 (a). It is a longitudinal cross-sectional view of the wiring board connection body which concerns on Embodiment 2 formed by connecting a high frequency cable, an adapter, and PWB. It is a longitudinal cross-sectional view which shows the structure of the wiring board connection body used for the simulation 1 of Fig.10 (a). It is a longitudinal cross-sectional view which shows the structure of the wiring board connection body used for the simulation 2 of FIG.10 (b). It is a longitudinal cross-sectional view which shows the example of the flat cable which can be used as a high frequency cable of this invention. (A)-(c) is a figure which simulates and shows the noise characteristic of the wiring board connection body of Embodiment 1, and another wiring board connection body.

Explanation of symbols

A High-frequency cable body B Wiring board connector 10 Adapter 11 Flat dielectric layer 12 First line conductor 13 Signal through-hole conductor 14 Second line conductor 15 Second ground plane 15a Base end portion 15b Side portion 15d Main portion 16 Ground Through-hole conductor 18 First ground plane 18a Main portion 18b Side portion 20 High-frequency cable 21 Cable line 22 Central conductor 23 Intermediate insulator 24 Outer insulator 25 Ground member 25a Upper ground member 25b Lower ground member 26 Outer skin 30 PWB
31 Rigid board 32 Wiring 38 Main ground plane

Claims (6)

An adapter structure connected to an end of a high-frequency cable having a center conductor and an outer conductor provided between each center conductor with a dielectric layer interposed therebetween,
A planar dielectric layer having a first surface and a second surface opposite the first surface;
A first line conductor formed on the first surface of the planar dielectric layer and connected to the central conductor;
A second line conductor formed on the second surface of the flat dielectric layer and connected to the wiring on the connected wiring board;
A signal through-hole conductor connecting the first line conductor and the second line conductor through the flat dielectric layer;
A first ground plane formed on the second surface of the planar dielectric layer so as to face the first line conductor and connected to the outer conductor;
With adapter structure. The adapter structure according to claim 1,
An adapter structure further comprising a second ground plane formed on the first surface of the flat dielectric layer so as to face the second line conductor and connected to the outer conductor. The adapter structure according to claim 1 or 2,
The high-frequency cable is an adapter structure that is a flat cable or a multi-core cable using a conductor having a round cross section. The adapter structure according to any one of claims 1 to 3,
A high-frequency cable having a center conductor connected to the first line conductor of the adapter structure, and an outer conductor provided with a dielectric layer sandwiched between the center conductors;
High frequency cable body equipped with. A high-frequency cable body according to claim 4,
A mother board having a dielectric substrate, wiring formed on the main surface of the dielectric substrate and connected to the second line conductor of the high-frequency cable body, and a main ground plane formed on the back surface of the dielectric substrate A substrate,
Wiring board connector comprising: In the wiring board connector according to claim 5,
A wiring board connector, wherein one connecting member selected from ACF, ACP, NCF, and NCP is provided at a connection portion between the second line conductor and the wiring.

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