WO2010042420A2

WO2010042420A2 - Board cable connection structure

Info

Publication number: WO2010042420A2
Application number: PCT/US2009/059491
Authority: WO
Inventors: Hiroyuki Matsuoka; Yoshihisa Kawate
Original assignee: 3M Innovative Properties Company
Priority date: 2008-10-08
Filing date: 2009-10-05
Publication date: 2010-04-15
Also published as: JP2010092740A; KR20110082543A; WO2010042420A3

Abstract

Provided is a board-cable connection structure that is capable of reducing size and height of connecting parts of cables and a circuit board without impairing reliability of electrical connection of cables and the circuit board. A board-cable connection structure comprises a circuit board 2, a multiplicity of cables 3, a relay connector 6 having FPC for electrically relaying and connecting the multiplicity of cables 3 to the circuit board 2, and a protective cover 7 that covers the relay connector 6 and prevents the relay connector 6 from moving in the direction separating away from the circuit board 2.

Description

BOARD CABLE CONNECTION STRUCTURE

Field of the Invention The present invention relates to a board-cable connection structure for electrically interconnecting cables and a circuit board that is applied, for example, to a mobile information apparatus such as a mobile phone.

Background As an example of a board-cable connection structure for electrically interconnecting electrical cables to a circuit board, there is disclosed a board-cable connection structure that connects cables to a circuit board via an electrical connector (see, for example, Patent Reference 1). In Patent Reference 1, in paragraph [0014], there is a description that "a cable connector 1 according to the present invention comprises, as shown in Fig. 1, a receptacle connector 3 that is surface-mounted to a printed circuit board

2, and a plug connector 5 fitted to the receptacle connector 3 from vertical direction of said printed circuit board 2 with a coaxial cable 4 soldered in parallel thereto". In paragraph [0022], there is a description that "as shown in Fig. 7 and Fig. 8, said receptacle connector 3 has a female contact 3b with alternately long and short legs to be connected to the printed circuit board 2 embedded in the housing body 3a", and in paragraph [0023], there is a description that "as shown in Fig. 8 (c), the contact parts 3d of the female contacts 3b are so formed by being bent as to be extended generally in parallel to the surface of said printed circuit board 2 at the lower position of male contacts 5b of said plug connector 5 to be generally vertically erected on the printed circuit board 2 along with contact parts 5f of the male contacts 5b to contact said contact parts 5f."

Thus, this board-cable connection structure is applied for electrical conduction of a coaxial cable to a circuit board, and comprises a receptacle connector that is surface- mounted to the circuit board, and a plug connector that is fitted to the receptacle connector from vertical direction of the circuit board. The receptacle connector has a female contact connected to the conductor section of the circuit board, and the plug connector has a male contact with one end soldered to a coaxial cable. By fitting the receptacle connector and the plug connector, the female contact and the male contact are electrically connected to bring the coaxial cable into contact to the circuit board.

[Patent Reference 1] Japanese Patent Publication No. 2005-302417.

Summary

In connection structure for connecting cables (electric wire) to a circuit board via a pair of connectors, a fitting mechanism is required for fitting the connectors to each other. In order to obtain reliable electrical contact of a male contact and a female contact, a structure in which one of the contacts is elastically sandwiched in vertical direction or in longitudinal direction (in the direction of cable axis) is often adopted, and it is required to provide a space in a part of the male contact for receiving at least a part of the female contact. Similarly, it is required to provide a recess in the female contact for receiving at least a part of the male contact. Thus, with the connection structure in which cables and a circuit board are electrically connected via a pair of connectors, there is necessarily a limit to reduction of size and height of connectors and reduction of mounting area of a circuit board, and there is a need for further size reduction of the connection structure.

As another method for connecting cables to a circuit board, a method is known in which a core of a cable is directly connected to a wiring conductor of a circuit board by using a conductive adhesive for circuit connection. In the cable connection structure connected in this method, however, when the cable is suddenly pulled, the tension is exerted directly to the connecting part of the core and the wiring conductor, and may break the connecting part. In addition, although a conductive adhesive has relatively high strength in the shear direction parallel to the adhesion plane, adhesive strength in the direction perpendicular to the adhesion plane is relatively small as compared to the adhesive strength in the shear direction parallel to the adhesion plane, and it is feared that the connecting part of the core and the wiring conductor may break when the cable is pulled perpendicular to the adhesion plane, that is, when the cable disposed parallel to the plane of the circuit board is pulled up from the plane of the circuit board.

It is an object of the present invention to provide a board-cable connection structure that is capable of reducing size and height of the structure of the connecting part of the cables and a circuit board without impairing reliability of electrical connection of the cables and the circuit board.

Brief Description of the Drawings Fig. 1 is a sectional view of a board-cable connection structure according to a first embodiment of the present invention;

Fig. 2 is a perspective view of the board-cable connection structure shown in Fig. i;

Fig. 3 is a perspective view of a relay connector; Fig. 4 is an exploded perspective view of the relay connector shown in Fig. 3;

Fig. 5 is a perspective view showing a variant of the board-cable connection structure according to the first embodiment of the present invention;

Fig. 6 is a sectional view of a board-cable connection structure according to a second embodiment of the present invention; Fig. 7 is a perspective view showing the state in which the cover member of the clamping unit is opened;

Fig. 8 is a perspective view showing the state in which the cover member of the clamping unit is closed;

Fig. 9 is a perspective view showing a variant of the board-cable connection structure according to the second embodiment;

Fig. 10 is a sectional view of the board-cable connection structure shown in Fig. 9; Fig. 11 is a perspective view of the clamping unit;

Fig. 12 is a perspective view showing a variant of the board-cable connection structure according to the second embodiment; Fig. 13 is a perspective view of the elastic member provided in the multiplicity of cables;

Fig. 14 is a perspective view of a board-cable connection structure according to a third embodiment of the present invention;

Fig. 15 is a partial sectional view of the board-cable connection structure shown in Fig. 14; Fig. 16 is a perspective view of the relay connector of the same board-cable connection structure shown in Fig. 14;

Fig. 17 is a perspective view showing the state in which the cover member of the clamping unit is opened; and

Fig. 18 is a perspective view showing the state in which the relay connector is set to the clamping unit shown in Fig. 17. Description of Reference Numerals

1, 51, 81, 101, 121 board-cable connection structure

2, 150 circuit board

3 cable

4a core

6, 91, 131 relay connector

7 protective cover

9, 59, 89, 133 FPC

11, 82, 132 flat plate

15 bulging section

15a ceiling wall

15b circumferential wall

16 flat section

17 long bar

21 opening

63, 83, 143 clamping unit

64, 84, 144 base member

66, 86, 146 cover member

67, 87 bottom wall

69 locking protrusion

72, 92 upper wall

74, 89 locking hole

75 contacting piece Detailed Description

In accordance with one aspect of the present invention, there is provided a board- cable connection structure, comprising: a circuit board, a multiplicity of cables, a relay connector having FPC for electrically relaying and connecting the multiplicity of cables to the circuit board; and a protective cover that covers the relay connector and prevents the relay connector from moving in a direction separating away from the circuit board.

In accordance with another aspect of the present invention, there is provided a board-cable connection structure, comprising: a circuit board, a multiplicity of cables, a relay connector having FPC for electrically relaying and connecting the multiplicity of cables to the circuit board; and a clamping unit that clamps both sides of the relay connector and prevents the relay connector from moving in a direction separating away from the circuit board.

In accordance with one aspect of the present invention, since the cables and the circuit board are connected via a relay connector, as compared to the case of using a conventional connector, the structure of the connecting part of the cables and the circuit board can be reduced in size and height. The relay connector is prevented from moving in the direction separating away from the circuit board by a protective cover or a clamping unit, so that the stress exerted to the connecting part of the core of the cable and the wiring conductor of the circuit board can be eliminated. Thus, even when unintended tension is suddenly applied to the cable, reliability of electrical connection between the cable and the circuit board can be maintained.

Now, various embodiments of the present invention will be described in detail below with reference to drawings showing specific exemplary embodiments thereof. These embodiments relate to a board-cable connection structure that can be used in representative applications. Representative applications include, but are not limited to, information apparatuses such as clamshell type or slide type mobile phones and smart phones. The board-cable connection structure according to the present invention electrically interconnects cables (small diameter coaxial cables) and a circuit board, and comprises a circuit board, a multiplicity of cables arranged in a row, a relay connector having FPC that is electrically interconnected at one end to the multiplicity of cables and electrically relayed at the other end to the circuit board, and protective means for preventing the separation of the relay connector from the circuit board to protect electrical connection of the cables and the circuit board. Examples of protective means include, but are not limited to, a protective cover and a clamping unit as will be described later.

A board-cable connection structure according to a first embodiment of the present invention will be described below. As shown in Fig. 1, board-cable connection structure 1 of this embodiment comprises circuit board 2, a multiplicity of cables 3 arranged in a row, a relay connector 6 for relaying and connecting core 4a and shield layer 4c of cable 3 to conductor sections 5 of circuit board 2 (see Fig. 4), and protective cover (protective means) 7 for covering relay connector 6. Forms of circuit board 2 include, but are not limited to, PCB (Printed Circuit

Board), FPC (Flexible Printed Circuit) having flexibility, and the like. FPC is a flexible circuit board formed, for example, of materials such as polyimide or the like of a few μm to a hundred μm in thickness with conductor sections disposed on the surface of the substrate. Representative form of PCB includes an insulating substrate formed of epoxy resin or the like with a multiplicity of wiring conductors in a specified pattern printed thereon. As will be described later, in the first embodiment wherein FPC 9 as relay connector 6 bent and folded in the shape of U beforehand is adhered to both front and back surfaces of flat plate 11, it is required to heat an adhesive for circuit connection disposed between circuit board 2 and relay connector 6 from the underside of circuit board 2 by a heater (not shown). Therefore, circuit board 2 of material and thickness not impairing heat conduction can be advantageously used. If, after one end of FPC 9 is connected (fixed) to circuit board 2, one end of FPC 9 along with circuit board 2 is bent and folded in the shape of U, circuit board 2 can be selected without taking heat conduction into account. On the portion of circuit board 2 to which relay connector 6 is fixed, one end of the wiring conductors is exposed at positions corresponding to the multiplicity of conductors of relay connector 6.

One form of cable 3 includes small diameter coaxial cable of about 0.3 mm in outer diameter. Cable 3 shown in Fig. 1 has conductive core 4a disposed in the center, with insulating inner covering 4b formed outside core 4a, shield layer 4c formed outside inner covering 4b, and insulating outer covering 4d formed outside shield layer 4c. In this way, cable 3 has multi-layered structure, with core 4a for transmitting signal and shield layer 4c insulated from each other by inner covering 4b, so that signal current is protected by shield layer 4c from noise to improve EMI characteristics.

Cable 3 is subjected to terminal processing such that outer covering 4d and inner covering 4b are respectively peeled off for a specified length at the distal end to expose core 4a and shield layer 4c. Noise current flowing in shield layer 4c is to be conducted via ground bar 8 and grounding conductor 10b of FPC (Flexible Printed Circuit) of relay connector 6 (Fig. 4) so as to flow in the wiring conductor (not shown) for grounding provided on the surface of circuit board 2. A multiplicity of cables 3 arranged in a row are sandwiched on shield layer 4c between a pair of ground bars 8 (see Figs. 1 and 4). Electrical connection between ground bar 8 and shield layer 4c can be accomplished by brazing or the like. A cable set is composed of a multiplicity of cables 3 and a pair of ground bars 8. Ground bar 8 is formed, for example, from plate material such as conductive copper alloy by punching in the shape of long piece with a press. By means of ground bar 8, shield layer 4c of all cables 3 is collectively connected.

A form of relay connector 6 may include, but is not limited to, flat plate 11 , as shown in Fig. 3 and Fig. 4, of length dimension W of 2 mm or less in forward/backward direction, height dimension T of 1 mm or less, and width dimension L of 15 mm or less in transverse direction with FPC 9 adhered to both front and back surfaces of flat plate 11. FPC 9 can be adhered to both front and back surfaces of flat plate 11 leaving both sides of flat plate 11. As will be described with reference to second and third embodiments, a relay connector having FPC 9 adhered to one surface of flat plate 11 may be used. Adhesives include, but are not specifically limited to, thermoplastic adhesives, heat curable adhesives, and adhesive sheets.

In this embodiment, FPC 9 is bent and folded in the shape of U, and is adhered to both front and back surfaces of flat plate 11. Long flat plate 11 may be formed of metal or resin material, as long as it can be formed with flatness, especially in longitudinal direction (width direction) at specified precision, but it is preferable that it be formed of metal material for which precision of flatness can be controlled easily. Thickness of flat plate 11 is arbitrary as long as required strength can be achieved. Preferably, thickness of flat plate 11 is about 0.2 mm, and in this case, flat plate 11 can be formed of stainless steel.

FPC 9 formed of base material of polyimide or the like of a few μm to lOOμm in thickness having conductor section disposed thereon may be used. Except for the portion required for electrical connection to circuit board 2 and cables 3, the conductor section is covered with resist (insulating covering). One surface of FPC is an adhesive surface, and the other surface is an electrical contact surface. The electrical contact surface has conductor section 10a for contacting with core 4a of cable 3, conductor section 10b for contacting via ground bar 8 with shield layer 4c of cable 3, a conductor section (not shown) for contacting with the conductor sections on circuit board 2, and a conductor section (not shown) for contacting with the wiring conductor for grounding on circuit board 2.

In this embodiment, since FPC 9 is adhered to flat plate 11 having good flatness via adhesive sheet 12 (Fig. 1), variation of respective height of conductor sections 10a, 10b is kept small. When relay connector 6 or circuit board 2 is deformed by the pressure at the time of hot press bonding, restoring force for restoring from the deformed state is exerted to the connecting part, and this may lead to separation of the relay connector from circuit board 2. In this embodiment, however, since excessive pressure is not required to connect conductor sections 10a, 10b to conductor sections 5 of circuit board 2, deformation of relay connector 6 or circuit board 2 is suppressed, and stress exerted to the connecting part is reduced, so that reliability of the connecting part is improved.

Fig. 3 is a view showing the state in which conductor sections 10a, 10b of FPC adhered to the front surface of flat plate 11 are connected to core 4a of cable 3 and to ground bar 8 by brazing, and the conductor sections of FPC 9 adhered to the back surface of flat plate 11 are connected via an adhesive for circuit connection (such as anisotropic conductive adhesive) to conductor sections 5 of circuit board 2 by hot press bonding. As shown, front surface of relay connector 6 is exposed, but it is also possible to cover it with a shield shell. In this case, an opening may be formed in the shield shell in the portion corresponding to the cable extraction side. A plurality of holes for brazing may be formed in the shield shell in order to braze ground bar 8 to the shield shell, or locking means may be provided for locking the shield shell to relay connector 6. It is also possible to electrically connect protective cover 7 to ground bar 8 by brazing or the like and to obtain the same function as the shield shell. By so doing, the connecting part of relay connector 6 and circuit board 2 or cable 3 can be shielded to improve EMI characteristics.

By using the relay connector 6 in place of a conventional connector comprising a connector housing and terminals, mounting area can be reduced, and the length (in the length direction of the cable) of relay connector 6 can be reduced to substantially same length as the portion of cable 3 having outer covering 4d removed. Width (in the direction of aligned cables 3) of the relay connector can be reduced to substantially the same dimension as the width of the multiplicity of cables 3. Protective cover 7 can be formed, for example from a metal panel by using a press, and as shown in Fig. 2, has bulging section 15 formed so as to bulge out to a size corresponding to relay connector 6 and flat section 16 continuing from the periphery of bulging section 15 to be fixed to circuit board 2. Flat section 16 is connected continuously to the edge of bulging section 15, and the back surface forms a fixing surface to be fixed via an adhesive or the like to the upper surface of circuit board 2. Bulging section 15 has ceiling wall 15a, and circumferential wall 15b continuing from edge 15c of ceiling wall 15a.

Opening 21 is formed in circumferential wall 15b of bulging section 15 for extracting multiplicity of cables 3. Height of bulging section 15 is comparable to that of relay connector 6 with cables 3 attached, and is preferably set such that, with protective cover 7 fixed to circuit board 2, there is no gap between the inner surface of the ceiling wall 15a of bulging section 15 and upper ground bar 8. By bringing the inner surface of ceiling wall 15a of bulging section 15 into contact with upper ground bar 8, movement of relay connector 6 in the direction Z separating away from circuit board 2, in other words, movement of relay connector 6 in the direction Z rising up (vertically) from circuit board 2, is prevented. Thus, even if cable 3 is pulled carelessly, stress is not exerted to the connecting part of cables 3 and circuit board 2, and the separation of the connecting part is avoided. By covering relay connector 6 in electrical connection with protective cover 7 by bulging section 15, shield characteristics of cable connection structure 1 can be improved. Fig. 5 is a view showing a variant of the first embodiment. As shown, long bar

(separation preventing member) 17 is retro-fitted around the multiplicity of cables 3 for preventing relay connector 6 from separating from circuit board 2. Long bar 17 can be formed of any material having required strength, for example, thermoplastic resin material. When long bar 17 is retrofitted, it can be provided so as to sandwich cables 3 between upper and lower resin members 18a, 18b. It is also possible to provide long bar 17 integrally with the multiplicity of cables 3, and in this case, long bar 17 can be molded from resin. Protective cover 7 has locking wall 20 (circumferential wall 15b) for locking both sides of long bar 17 provided on both sides of opening 21 for extracting cables 3. When cable 3 is pulled, long bar 17 abuts against the inner surface of locking wall 20 to thereby prevent relay connector 6 from moving in forward/backward direction. Separation of relay connector 6 together with a multiplicity of cables 3 from circuit board 2 is thereby prevented.

It is also possible to impart adhesive property to the surface of the long bar in contact with the circuit board and the protective cover, for example by applying an adhesive, to thereby seal opening 21 formed in circumferential wall 15b of bulging section 15 with the long bar. Alternatively, it is also possible to seal opening 21 formed in circumferential wall 15b of bulging section 15 with the long bar by forming the long bar as an integrally formed elastic material around the multiplicity of cables 3 and by compressing the long bar elastically between the protective cover and the circuit board. By sealing opening 21 with the long bar, ingress of liquid such as water or dust into the inside of protective cover 7 can be prevented.

Next, a board-cable connection structure according to a second embodiment of the present invention will be described. As shown in Fig. 6 to Fig. 8, board-cable connection structure 51 according to this embodiment differs from board-cable connection structure 1 according to the first embodiment in that flat plate 11 of relay connector 6 is clamped at both sides by clamping unit (protective means) 63 on circuit board 2, and protective cover 7 is not used.

Like the protective cover shown in Fig. 1, clamping unit 63 prevents relay connector 6 from moving in the direction separating away from circuit board 2, mainly in vertical direction Z, so that, even if cable 3 is suddenly pulled carelessly, stress is not exerted to the connecting part of core 4a and conductor section 5 of circuit board 2. Clamping unit 63 according to the present embodiment is composed of base member 64 fixed on circuit board 2 and cover member 66 interconnected to base member 64 via interconnecting pin 65 so as to permit opening and closing, although the construction of clamping unit 63 is not limited to such construction (Fig. 7 and Fig. 8). It is also possible to interconnect the cover member detachably to the base member without using interconnecting pin 65.

As shown in Fig. 7 and Fig. 8, base member 64 can be formed, for example, by punching and bending a thin plate metal panel using a press, and has bottom wall 67 and both side walls 68. End of relay connector 6 (end of flat plate 11) can be attached from the insertion end formed as an opening at one end of both side walls 68. On the opposite side of the insertion end, interconnecting pin 65 is pressed into both side walls 68, and cover member 66 is rotatably interconnected to interconnecting pin 65. Lower surface of bottom wall 67 of base member 64 is a fixation surface to be fixed to the upper surface of circuit board 2 by an adhesive or by brazing. On the outer surface of both side walls 68 that stand up from bottom wall 67 of base member 64, locking protrusion 69 is provided to be engaged with locking hole 74 provided in side wall 73 of cover member 66. Locking protrusion 69 may have an inclined surface on which the distal end of side wall 73 of cover member 66 slides, and a locking surface that continues from the inclined surface and abuts against the hole edge of locking hole 74. Between both side walls 68 of base member 64, end of flat plate 11 of relay connector 6 is attached so as to prevent relay connector 6 from moving in the direction of opposing both side walls 68, that is, in the forward/backward direction Y shown in Fig. 6.

Like base member 64, cover member 66 can also be formed, for example, by punching and bending a thin plate metal panel using a press, and has upper wall 72 and both side walls 73. On one side of both side walls 73, it has tongue-shaped contacting piece 75 which bends inward from the basal end to the distal end at the end of upper wall 72 and extends inside, and a pair of interconnecting pieces 76 at the other side of both side walls 73 to be interconnected to interconnecting pin 65. Contacting piece 75 is provided so as to be able to contact with the upper surface of flat plate 11 to prevent, coupled with flat plate 11, relay connector 6 from moving in the direction Z rising up from circuit board 2, that is, in the direction for the relay connector to be separated from circuit board 2. Locking hole 74 is provided in both side walls 73 of cover member 66, such that, when side wall 73 of cover member 66 is superposed on the outer surface of side wall 68 of base member 64 and locking hole 74 is engaged with locking protrusion 69, cover member 66 is locked to base member 64.

Since clamping unit 63 according to the present embodiment comprises a mechanical locking mechanism, unclamp state can be achieved by unlocking it and releasing cover member 66. In unclamp state, replacement and maintenance service of relay connector 6 can be done.

Figs. 9 and 10 are views showing a variant of the second embodiment. In this variant, base member 84 of clamping unit 83 is formed as a component. Relay connector 91 has FPC 89 adhered to only one surface of flat plate 82. FPC 89 extends from one end to the other end, and the one end connected to cable 3 is fixed to flat plate 82, and the other end is fixed to circuit board 2 via an adhesive for circuit connection by hot press bonding.

In this variant, relay connector 91 is fixed with the surface of FPC 89 connected to cable 3 facing to circuit board 2. By so fixing relay connector 91, positioning of FPC 89 to circuit board 2 is facilitated. Since flat plate 82 covers the connecting part of cable 3 and FPC 89, sudden short-circuiting can be avoided without a protective cover. Since the conductor sections of FPC 89 needs to be exposed only on one surface, construction of FPC 89 itself can be simplified, and since need of a via conductor for conduction between the upper and lower surfaces of FPC 89 is eliminated, it is possible to reduce the size of FPC 89.

As shown in Fig. 11 in detail, cover members 86 are interconnected rotatably via interconnecting pins 85 on both sides of base member 84. As shown, both sides of flat plate 82 of relay connector 91 are clamped between both side portions of base member 84 and cover members 86 that are moved in opening/closing operation.

Base member 84 has bottom wall 87, side walls 88 that stand up vertically on both sides of bottom wall 87, and a pair of bent pieces 90a, 90b opposed to side wall 88. Interconnecting pin 85 is pressed into a through-hole formed in one of bent piece 90a and side wall 88 opposed to bent piece 90a. Link section 97 formed in the shape of U at one end of cover member 86 is rotatably connected to interconnecting pin 85. Locking hole 94 to be engaged with a locking protrusion (not shown) provided on side wall 93 of cover member 86 is formed in the other bent piece 90b. Locking hole 94 is also formed in side wall 88 of base member 84 at a position opposed to locking hole 94 formed in bent piece 90b. When the locking protrusion provided on side wall 93 of cover member 86 is engaged with two locking holes 94 provided in bent piece 90b and side wall 88, cover member 86 is locked to base member 84, and both sides of flat plate 82 of relay connector 91 are clamped between base member 84 and cover member 86.

Cover member 86 has upper wall 92, side walls 93 that continue from the edge of upper wall 92 and are superposed on side wall 88 and bent piece 90b of base member 84, and link section 97 in the shape of U rotatably interconnected to interconnecting pin 85 provided in base member 84. A locking protrusion is formed on side wall 93 at a position to be engaged with locking holes 94 formed in side wall 88 and bent piece 90b of base member 84. Preferably, cover member 86 is formed in dimensions suitable to be elastically sandwiched between side wall 88 and a pair of bent pieces 90b of base member 84. Looseness of base member 84 and cover member 86 in the clamp state can be thereby effectively suppressed.

In the clamp state of clamping unit 83, both sides of flat plate 82 of relay connector 91 are clamped between bottom wall 87 of base member 84 and upper wall 92 of cover member 86. Since flat plate 82 is positioned between both side walls 88 of base member 84, relay connector 91 is prevented from moving in left/right direction X, and since flat plate 82 is positioned between a pair of bent pieces 90a, 90b, relay connector 91 is prevented from moving in forward/backward direction Y, and since flat plate 82 is positioned between bottom wall 87 of base member 84 and upper wall 92 of cover member 86, relay connector 91 is prevented from moving in up/down direction Z (see Fig. 9). In this variant, a portion corresponding to tongue-shaped contacting piece 75 shown in Fig. 7 may be provided in base member 84 or cover member 86.

Fig. 12 is a view showing another variant of the second embodiment. As shown, in this variant, protective cover 7 for covering relay connector 91 and clamping unit 83, and long bar 110 integrally provided around the multiplicity of cables 3 are included. Since protective cover 7 is equivalent to protective cover 7 shown in Fig. 2, duplicate explanation of protective cover 7 is omitted. The shield characteristic of cable connection structure 101 is improved by protective cover 7 that covers relay connector 91. As shown in Fig. 13, long bar 110 is preferably provided integrally by resin molding to eliminate any gap between the multiplicity of cables 3 and long bar 110 so as to seal opening 21 formed in circumferential wall 15b of bulging section 15. By sealing opening 21 with long bar 110, ingress of liquid such as water or dust from outside into the interior of protective cover 7 can be avoided, and the water-proof property and the dust- proof property of cables 3 and circuit board 2 can be improved. Relay connector 91 is prevented from moving in the forward/backward direction Y by the long bar abutting to locking wall 20 of protective cover 7 (see Fig. 5).

Long bar 110 is a member corresponding to long bar 17 shown in Fig. 5, and an adhesive may be applied to long bar 110 to seal opening 21. Alternatively, long bar 110 may be elastically compressed between protective cover 7 and circuit board 2 to seal opening 21.

Next, a board-cable connection structure according to a third embodiment of the present invention will be described. As shown in Fig. 14 to Fig. 18, board-cable connection structure 121 of this embodiment differs from board-cable connection structure

81, 101 of the second embodiment in that clamping unit 143 for clamping both sides of flat plate 132 of relay connector 131 is disposed in recess 151 provided in the periphery of circuit board 150, whereas, in board-cable connection structure 81, 101 of the second embodiment, clamping unit 83 is provided on circuit board 150. Since board-cable connection structure 121 is disposed in recess 151, board-cable connection structure 121 is prevented from projecting in thickness direction of circuit board 150, which makes it possible to keep the height dimension small and to obtain a thin enclosure.

As shown in Figs. 14 and 15, recess 151 of a size corresponding to clamping unit 143 is provided in the periphery on one side of circuit board 150. Clamping unit 143 is disposed so as to be generally contained in recess 151. Clamping unit 143 is fixed to circuit board 150 by a pair of arms 145 extended from both sides of base member 144 in width direction being soldered to circuit board 150, but is not limited to such construction. Clamping unit 143 and circuit board 150 may be fixed to each other by an adhesive, by screw fastening or by snap-fit method. In place of clamping unit 143 being fixed to circuit board 150, an adhesive may be provided on the back of the base of clamping unit 143 to fix clamping unit 143 to the inner surface of the enclosure in which the circuit board is contained, for example, the enclosure of a mobile phone.

Fig. 16 is a view showing relay connector 131 that is clamped by clamping unit 143 of the present embodiment as seen from the side of the back surface. On one side of FPC 133, cores 4a of cables 3 are brazed to signal wiring conductor 10a exposed to the back surface. A pair of ground bars 8 connected to shield layer 4c of cables 3 are brazed to ground wiring conductor 10b for grounding of FPC 133. Flat plate 132 is bonded to the front surface of FPC 133 by an adhesive or the like. Both sides of flat plate 132 are extended on both sides in the width direction of FPC 133 such that the extension can be clamped by clamping unit 143. On the other side of FPC 133, signal wiring conductors 10a are exposed on the back surface of FPC 133 that is hot-press-bonded to circuit board 150.

Fig. 17 is a view showing clamping unit 143 disposed in recess 151 of circuit board 150. Base member 144 is same as base member 84 shown in Fig. 11 except that it is fixed to circuit board 150 by a pair of arms 145. On both sides of base member 144, cover member 146 is rotatably interconnected via interconnecting pin 85. Interconnecting pin 85 is pressed into a through-hole formed in one bent piece 90a and in side wall 88 opposed to bent piece 90a.

Base member 144 has bottom wall 87, side walls 88 that stand up vertically on both sides of bottom wall 87, and a pair of bent pieces 90a, 90b opposed to side wall 88. Interconnecting pin 85 is pressed into one of bent pieces 90a, and in the other bent piece 90b, locking hole 94 to be engaged with locking protrusion 153 provided on side wall 93 of cover member 146 is formed. Locking hole 94 is also formed in side wall 88 of base member 144 at a position opposed to the locking hole formed in bent piece 90b. By the engagement of locking protrusion 153 provided on side wall 93 of cover member 146 with two locking holes 94 provided in bent piece 90b and side wall 88, cover member 86 is locked to base member 84, and both sides of flat plate 132 of relay connector 131 are clamped between base member 144 and cover member 146. Arm 145 to be fixed to circuit board 150 is provided on each of side walls 88. Arm 145 has a basal side that continues from side wall 88, and a distal side that continues from the basal side and is bent parallel to circuit board 150. Arm 145 is adhered at the flat surface at the distal end to circuit board 150. Cover member 146 is also similar to cover member 86 shown in Fig. 11, and has upper wall 92, side walls 93 that continues from the edge of upper wall 92 and is superposed on side wall 88 and bent piece 90b of base member 144, and link section 97 in the shape of U rotatably interconnected to interconnecting pin 85. Locking protrusion 153 is formed on side wall 93 at a position to be engaged with locking holes 94 formed in side wall 88 and bent piece 90b of base member 144.

Fig. 18 is a view showing relay connector 131 that is attached to clamping unit 143 in unclamp state. Both sides of flat plate 131 are positioned between both sides of base member 144 and cover member 146. By closing cover member 146, both sides of flat plate 132 are clamped between both sides of base member 144 and cover member 146. As shown in Fig. 15, in clamp state, both sides of flat plate 132 are preferably in close contact with the underside of upper wall 92 of cover member 146 without gap, and both sides of flat plate 132 are preferably in contact with the inner surface of side walls 93 of cover member 146. Relay connector 131 can be thereby fixed by the clamping unit without looseness. In this embodiment, it is also possible to provide a portion that corresponds to tongue-shaped contacting piece 75 shown in Fig. 7 in base member 144 or cover member 146.

In accordance with the third embodiment, relay connector 131 is prevented by clamping unit 143 from moving in left/right direction X, in forward/backward direction Y, and in up/down direction Z. Since clamping unit 143 is disposed in recess 151 of circuit board 150, projection of clamping unit 143 from circuit board 150 is suppressed, and therefore, size and height of connection structure 121 of present invention can be further reduced.

The board-cable connection structure according to the present invention has been described above with reference to embodiments thereof. The present invention, however, can be implemented in other forms and is to be limited only by the appended claims and equivalents thereof.

Claims

What is claimed is:

1. A board-cable connection structure comprising: a circuit board; a multiplicity of cables; a relay connector having FPC for electrically relaying and connecting said multiplicity of cables to said circuit board; and a protective cover that covers said relay connector and prevents said relay connector from moving in a direction separating said relay connector away from said circuit board.

2. A board-cable connection structure according to claim 1, wherein said protective cover has a ceiling wall and a circumferential wall that continues from an edge of said ceiling wall, and wherein said relay connector is prevented from moving in said direction separating said relay connector away from said circuit board by abutting of said relay connector against an inner surface of said ceiling wall.

3. A board-cable connection structure according to claim 2, wherein a separation preventing member is mounted around said multiplicity of cables such that, when said multiplicity of cables are pulled, said separation preventing member abuts against said inner surface of said circumferential wall of said protective cover to thereby prevent said relay connector from moving in said direction separating said relay connector away from said circuit board.

4. A board-cable connection structure according to claim 2 or 3, wherein an opening for extracting said multiplicity of cables is formed in said circumferential wall of said protective cover, and wherein a sealing member for sealing said opening is integrally provided on said multiplicity of cables.

5. A board-cable connection structure, comprising: a circuit board; a multiplicity of cables; a relay connector having FPC for electrically relaying and connecting said multiplicity of cables to said circuit board; and a clamping unit that clamps both sides of said relay connector and prevents said relay connector from moving in a direction separating said relay connector away from said circuit board.

6. A board-cable connection structure according to claim 5, wherein a recess is provided in a peripheral portion of said circuit board, and wherein said clamping unit is disposed in said recess.

7. A board-cable connection structure according to claim 5 or 6, wherein said clamping unit comprises a base member fixed to said circuit board and a cover member mounted to said base member so as to permit opening and closing, and wherein both sides of said relay connector are clamped between said base member and said cover member.

8. A board-cable connection structure according to claim 7, wherein said base member has a locking section and said cover member has a locked section, and wherein said cover member is locked to said base member by engagement of said locked section with said locking section.