WO2009114225A1

WO2009114225A1 - Board-cable connection structure, manufacturing method of relay connector and fixation method of relay connector

Info

Publication number: WO2009114225A1
Application number: PCT/US2009/033663
Authority: WO
Inventors: Hiroyuki Matsuoka; Yoshihisa Kawate
Original assignee: 3M Innovative Properties Company
Priority date: 2008-03-07
Filing date: 2009-02-10
Publication date: 2009-09-17
Also published as: JP5213629B2; JP2009238728A

Abstract

The present invention provides a board-cable connection structure and a manufacturing method of a relay connector and a fixation method of a relay connector that is capable of making the connection structure of cables and circuit board smaller in size and height. A board-cable connection structure including: a multiplicity of cables arranged in a row, and relay connector having plate and FPC of which at least one end of a first surface is fixed to the front surface of plate, wherein FPC has a first electrical contact surface having first conductor sections electrically connected to the multiplicity of cables on one end side of a second surface, a second electrical contact surface having exposed second conductor sections to be connected to circuit board on the other end side of the second surface, and a bent section folded in the shape of U between one end side and the other end side.

Description

BOARD-CABLE CONNECTION STRUCTURE, MANUFACTURING METHOD OF RELAY CONNECTOR AND FIXATION METHOD OF RELAY

CONNECTOR

TECHNICAL FIELD The present invention relates to a board-cable connection structure for electrically connecting cables to a circuit board, to a manufacturing method of a relay connector and to a fixation method of a relay connector.

BACKGROUND ART

An example of prior art related to the subject of the present invention can be found in a board-cable connection structure for electrically connecting cables to a circuit board via a connector (for example, see Japanese Patent Publication (Kokai) No. 2005-302417). Japanese Patent Publication (Kokai) No. 2005-302417, as stated in paragraph 0014, includes the description that "cable connector 1 according to the present invention comprises, as shown in Fig. 1, receptacle connector 3 that is surface-mounted to printed circuit board 2 and plug connector 5 that is fitted to receptacle connector 3 from a direction perpendicular to printed circuit board 2 and that is provided with soldered coaxial cable 4 in parallel." In paragraph 0022, there is the description that "as shown in Figs. 7 and 8, receptacle connector 3 has female contact 3b embedded therein with alternately short and long legs for connecting printed circuit board 2 to main housing 3a." Further, in paragraph 0023, there is the description that "a contact section 3d of the female contact 3b is, as shown in Fig. 8(c), is provided generally in parallel to the surface of printed circuit board 2 at a position below male contact 5b of plug connector 5 and, is erected together with contact section 5f of male contact 5b generally in a direction perpendicular to printed circuit board 2, and is formed to bend so as to come into contact with contact section 5f."

Thus, a board-cable connection structure which is applied to electrical conduction of small size coaxial cables to a circuit board, comprises a receptacle connector that is surface-mounted to the circuit board and a plug connector that is fitted to the receptacle connector from a direction perpendicular to the circuit board, wherein the receptacle connector has a female contact connected to the circuit board and the plug connector has a male contact with one end thereof soldered to coaxial cables, and wherein, by fitting the plug connector to the receptacle connector, the female contact and the male contact are electrically connected to each other, resulting in electrical conduction of the coaxial cables to the circuit board.

In a connection structure for electrically connecting a cable to a circuit board via a pair of connectors, it is required to provide a fitting mechanism for fitting the connectors to each other. In order to ensure reliable electrical contact between a male contact and a female contact, these contacts are often constructed such that one of the contacts is elastically sandwiched by the other of the contacts in a vertical direction or in a longitudinal direction (in the direction of cable axis). To this end, it is necessary to provide a space in a part of the male connector for receiving at least a part of the female contact. Similarly, it is also necessary to provide a recess in a part of the female connector for receiving at least a part of the male connector. Therefore, in a connection structure for electrically connecting a cable to a circuit board via a pair of connectors, there is an inevitable limit to reduction of size and height of connectors and to reduction of the mounting area of a circuit board. In view of constant trend and demand for reduction of size and height of an electronic apparatus such as a mobile phone or a mobile information terminal, there is still continuing need to further reduce the size of a connection structure. In the connection of coaxial cables to a circuit board, coaxial cables interfere with circuit components mounted on the circuit board, and this poses an inevitable limit to increasing mounting density of circuit components on the board. A multiplicity of coaxial cables arranged in a row are bundled at the proximal end for easy handling of the coaxial cables in the enclosure, and when a multiplicity of coaxial cables are bundled, the coaxial cables positioned on both sides of the bundle tend to be pulled more strongly, and this may impair the connection reliability of electrical connection. SUMMARY

It is an object of the present invention to provide a board-cable connection structure and a manufacturing method of a relay connector and a fixation method of a relay connector that permit the structure of the connecting part of the cables and a circuit board to be reduced in size and height, and permit the enclosure to be made more compact. In accordance with one aspect of the present invention, there is provided a board- cable connection structure comprising a multiplicity of cables arranged in a row, and a relay connector having a plate and a FPC of which at least one end of a first surface is fixed to the front surface of the plate, wherein the FPC has a first electrical contact surface comprising first conductor sections electrically connected to the multiplicity of cables on one end side of a second surface, a second electrical contact surface comprising exposed second conductor sections to be connected to a circuit board on the other end side of the second surface, and a bent section to be folded in a shape of U between the one end side and the other end side of the second surface.

In accordance with another aspect of the present invention, there is provided a fixation method for fixing a relay connector, comprising: electrically connecting the second conductor section of the FPC of the relay connector according to claim 1 to a conductor section of a circuit board, and thereafter, folding one end side of the FPC with generally middle portion of the FPC as a fulcrum in a shape of U and fixing it to the back surface or the front surface of the plate.

In accordance with another aspect of the present invention, there is provided a fixation method for fixing a relay connector, comprising: fixing a base member having a cover member interconnected to a circuit board so as to permit opening and closing; disposing one end side of the FPC of the board-cable connection structure on the inner surface of the opened cover member; electrically connecting the second conductor section on the other end side of the FPC to the conductor section of the circuit board; folding one end side of the FPC in a shape of U by rotating said cover member in closing direction with generally middle portion of the FPC as a fulcrum; and locking the cover member to the base member to thereby hold the FPC folded in the shape of U.

In accordance with another aspect of the present invention, there is provided a board-cable connection structure comprising: a multiplicity of cables arranged in a row, and a relay connector having a plate and a FPC folded and fixed to the plate from the front surface to the back surface thereof in a shape of U; wherein the relay connector has a first electrical contact surface comprising first conductor sections electrically connected to the multiplicity of cables on one surface, and a second electrical contact surface comprising exposed second conductor sections to be connected to a circuit board on the other surface. In accordance with another aspect of the present invention, there is provided a manufacturing method for manufacturing a relay connector for relaying and connecting a multiplicity of cables to a circuit board comprising: providing a FPC having a multiplicity of conductor sections arranged at a specified interval on a front surface and a fixing surface on a back surface; centering the FPC to a plate to which the FPC is to be fixed with the conductor sections of the FPC facing outward, and fixing the fixing surface on one end side of the FPC to the front surface of the plate; and folding the other end side of the FPC not fixed to the plate with a portion positioned in the vicinity of the edge of the plate as a fulcrum to the back surface of the plate in a shape of U, and fixing the fixing surface of the other end side of the FPC to the back surface of the plate.

In accordance with another aspect of the present invention, there is provided a board-cable connection structure comprising: a multiplicity of cables arranged in a row; and a multiplicity of relay connectors connected to the end of the multiplicity of cables; wherein the multiplicity of relay connectors are arranged in a radiation pattern around an assembly section assembling the multiplicity of cables derived from the multiplicity of relay connectors, with a derived cable end of the multiplicity of relay connectors facing inward.

Since, in accordance with the present invention, a relay connector is used in place of a board side connector to be fitted to a cable side connector, the structure of connecting part of a circuit board and cables can be made smaller in size and height compared to conventional connector. This permits an electronic apparatus or the like to which the board-cable connection structure 1 of the present invention is applied to be made smaller in size and height. Since, in accordance with another aspect of the present invention, a multiplicity of relay connectors are arranged in a radiation pattern with the derived cable ends facing inward, space for mounting circuit components can be increased near the connecting part of the cables and the circuit board, and mounting density of circuit components can be thereby increased. Degree of freedom of circuit design can be thereby increased, and the enclosure can be made more compact. In addition, tension produced when cables are bundled can be reduced, and reliability of electrical connection can be improved.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is an exploded perspective view of a board-cable connection structure according to a first embodiment of the present invention; Fig. 2 is a perspective view showing the assembled state of the board-cable connection structure shown in Fig. 1; Fig. 3 is a view showing the board-cable connection structure as viewed from the back side;

Fig. 4 is a sectional view showing the board-cable connection structure as electrically connected to a circuit board; Fig. 5 is a perspective view for explaining a method of manufacturing the board- cable connection structure of Fig. 1 shown with FPC situated in opposition to the plate;

Fig. 6 is a perspective view for explaining the method of manufacturing the board- cable connection structure shown with generally half of FPC adhered to the plate;

Fig. 7 is a perspective view for explaining the method of manufacturing the board- cable connection structure shown with generally half of FPC which is not yet adhered being bent downward along the plate;

Fig. 8 is a perspective view for explaining the method of manufacturing the board- cable connection structure shown with FPC adhered to both front and back surfaces of the plate; Fig. 9 is a perspective view of a relay connector obtained by cutting the distal end side of the plate having FPC adhered thereto;

Fig. 10 is a perspective view of a board-cable connection structure according to a second embodiment of the present invention;

Fig. 11 is a perspective view of a board-cable connection structure according to a third embodiment of the present invention;

Fig. 12 is a perspective view of the plate of the relay connector shown in Fig. 11;

Fig. 13 is a perspective view showing the state before FPC of the relay connector is folded in the shape of U;

Fig. 14 is a perspective view showing the state in which the conductor sections of FPC of the relay connector shown in Fig. 13 are electrically connected to FCB;

Fig. 15 is a sectional view of the relay connector obtained by folding FPC together with the circuit board to the plate side in the shape of U;

Fig. 16 is a sectional view of the relay connector obtained by folding FPC together with the circuit board to the cable side in the shape of U; Fig. 17 is a perspective view of a board-cable connection structure according to a fourth embodiment of the present invention; Fig. 18 is a perspective view of the relay connector of the board-cable connection structure shown in Fig. 17;

Fig. 19 is a perspective view of the relay connector of the same board-cable connection structure as seen from the back side; Fig. 20 is a perspective view of the same board-cable connection structure in the state with the cover member opened relative to the base member;

Fig. 21 is a sectional view of the same board-cable connection structure in the state with the cover member opened relative to the base member;

Fig. 22 is a sectional view of the same board-cable connection structure in the state with the cover member closed relative to the base member;

Fig. 23 is a plan view showing the state in which a multiplicity of cables are connected to one relay connector;

Fig. 24 is a plan view of a board-cable connection structure according to a fifth embodiment of the present invention; Fig. 25 is a plan view showing a variant of the board-cable connection structure shown in Fig. 24;

Fig. 26 is a plan view showing another variant of the board-cable connection structure shown in Fig. 24;

Fig. 27 is a partially enlarged view of the relay connector shown in Fig. 26; Fig. 28 is a sectional view showing another form of a board-cable connection structure in which the cable set and FCB are arranged in a longitudinal direction, showing (a) the state before FPC is hot press bonded to FCB, (b) the state in which FPC is hot press bonded to FCB, and (c) the state in which the cable set and FCB are longitudinally arranged on a positioning jig; Fig. 29 is a sectional view showing another form of manufacturing method of the board-cable connection structure, showing (a) the state before FPC is bent and folded, (b) the state before FPC is bent and folded upward in the shape of U, (c) the state in which the board-cable connection structure together with cables is being (passed) through the inner space of the hinge section; and (d) the state in which FPC is folded downward in the shape of U; and

Fig. 30 is a perspective view showing a variant of the board-cable connection structure having a photoelectric conversion module mounted to the relay connection block. DETAILED DESCRIPTION

Now, the present invention will be described in detail below with reference to drawings showing specific examples of 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, clamshell type or slide type mobile phones and information apparatuses such as smart phones. The board-cable connection structure is for connecting cables (electric wires) 2 and circuit board 8, and comprises a multiplicity of cables 2 arranged in a row, and relay connector 12 for relaying and connecting core 3 a and shield layer 3 c of the cable to conductor section 7 of circuit board 8.

Fig. 1 and Fig. 2 are views showing board-cable connection structure 1 according to a first embodiment of the present invention. Board-cable connection structure 1 may have width dimension W in forward/backward direction of 2 mm or less, height dimension T of 1 mm or less, and length dimension L in transverse direction of 15 mm or less. One form of cable 2 includes small diameter coaxial cable of about 0.3 mm in outer diameter. Small diameter coaxial cable 2 shown in Fig. 1 has conductive core 3a disposed in the center, with insulating inner covering 3b disposed outside core 3 a, shield layer 3c disposed outside inner covering 3b, and insulating outer covering 3d disposed outside shield layer 3c. In this way, cable 2 has multi-layered structure, with core 3a for transmitting signal and shield layer 3c insulated from each other by inner covering 3b, so that signal current is protected by shield layer 3 c from noise so as to improve EMI characteristics.

Small diameter coaxial cable 2 is subjected to terminal processing such that outer covering 3d and inner covering 3b are respectively peeled off for a specified length at the distal end to expose core 3a and shield layer 3c. Noise current flowing in shield layer 3c is conducted via ground bar 4 and relay connector 12 to flow in the wiring conductor (not shown) for grounding connection provided on the surface of circuit board 8.

Forms of circuit board 8 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 of materials such as polyimide or the like of a few μm to a hundredμm in thickness with conductor disposed on the surface of the substrate. Representative forms of PCB include 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, it is required to heat an adhesive for circuit connection disposed between circuit board 8 and the relay connector from the underside of circuit board 8 by a heater. Therefore, circuit board 8 of material and thickness not impairing heat conduction can be advantageously used. In this respect, FPC is suitable since it has a thin base material, has good thermal conductivity and high heat resistance. On the portion of circuit board 8 where relay connector 12 is fixed, one end of the wiring conductors is exposed at positions corresponding to the multiplicity of conductor sections 21 of relay connector 12.

A multiplicity of small diameter coaxial cables 2 arranged in a row are sandwiched between a pair of ground bars 4 sandwiching shield layer 3c. Electrical connection between ground bar 4 and shield layer 3c can be accomplished by brazing or the like. Cable set 5 is formed from a multiplicity of small diameter coaxial cables 2 and a pair of ground bars 4. Ground bar 4 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 4, shield layer 3c of all cables 2 is collectively connected.

Upper ground bar 4 and core 3a of cable set 5 are covered and shielded by shield shell 6 fixed to relay connector 12. Shield shell 6 has upper wall section 9a and side wall 9b that continues from the edge of upper wall section 9a. The portion of shield shell 6 corresponding to the cable derivation side is formed as an opening. In upper wall section 9a of shield shell 6, hole sections 9c for brazing are provided at four locations, such that upper ground bar 4 and shield shell 6 may be brazed to each other at the locations of hole sections 9c. In addition, or in place of hole sections, shield shell 6 and relay connector 12 may be fixed together by engaging means such as latches or the like.

As a non- limiting embodiment, relay connector 12 may be formed of FPC 13 adhered to both front and back surfaces of flat plate 14. FPC 13 is bent in a shape of U near the edge of flat plate 14. Long flat plate 14 may be formed of metal or resin material, as long as it can be formed with flatness, especially in a 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 14 is arbitrary as long as required strength can be achieved. For example, when stainless steel is used, thickness may be about 0.2 mm.

FPC 13 formed of base material of polyimide or the like of a few μm to lOOμm in thickness having conductor disposed thereon may be used. Except for the portion required for electrical connection to circuit board 8 and cables 2, the wiring conductor is covered with resist 27. One surface of FPC is formed as adhesive surface 19, and the other surface is formed as electrical contact surfaces 20a, 20b, 20c (see Fig. 5). Electrical contact surface (a first electrical surface) 20a has a plurality of conductor sections 21a for contacting with core 3 a of cable 2. Number of conductor sections 21a is usually the same as the number of cables 2. Pitch of conductor sections 21a is formed at an interval corresponding to the pitch of core 3a of coaxial cables 2. Electrical contact surface (a second electrical surface) 20b has conductor sections 21b connected to ground bar 4, electrically separated from conductor sections 21a, 21c with resist 27. Conductor sections 21a, 21b are electrically disconnected so that core 3 a and shield layer 3 c are insulated from each other. Figs. 5, 10, 11, 15, 16, 21, 22 all show core 3a and shield layer 3c insulated from each other. Electrical contact surface (a third electrical surface) 20c comprises conductor sections 21c for contacting with the wiring conductor on circuit board 8. Pitch of conductor sections 21c is formed at an interval corresponding to the pitch of conductor sections 7 of circuit board 8. A part of electrical contact surface 20c may constitute the bent section in the shape of U of FPC 13. Conductor sections 21c include conductor sections 21c electrically connected to conductor sections 21a, and conductor sections 21c electrically connected to conductor sections 21b and electrically disconnected to conductor sections 21a. Thus, connection of signal line (core 3a) and connection of ground line (shield layer 3 c) can be simultaneously accomplished to circuit board 8 via conductor sections 21a and conductor sections 21b.

In this embodiment, since FPC 13 is adhered to flat plate 14 having good flatness, variation of height of conductor sections 21 disposed on respective electrical contact surface 20 can be kept small. Therefore, when board-cable connection structure 1 is connected to circuit board 8 by hot press bonding or the like, excessive pressure needs not be exerted in order to bring conductor section 21c of electrical contact surface 20c into physical contact with conductor section 7 of circuit board 8. When board-cable connection structure 1 or circuit board 8 is deformed by the excessively high pressure at the time of connection, restoring force for restoring from the deformed state is exerted to the connecting part, and this may act so as to separate the conductors from each other. In this embodiment, however, since deformation of board-cable connection structure 1 or circuit board 8 is kept small, the stress exerted to the connecting part between the conductors is reduced, so that reliability of the connecting part is improved.

Fig. 2 is a view showing the state in which a multiplicity of coaxial cables 2 covered by the shield shell are connected to the upper side of board-cable connection structure 1, and Fig. 3 is a view showing the state in which electrical contact surface 20 of relay connector 12 is exposed on the underside of board-cable connection structure 1. Such board-cable connection structure 1 is connected to circuit board 8 by using an adhesive for circuit connection or the like. Therefore, need to provide a member such as a female connector for mechanically fixing the board-cable connection structure 1 on the circuit board 8 is eliminated. Mounting area can be thereby reduced substantially to the size of board-cable connection structure 1. Length (in axial direction of cable) of relay connector 12 can also be reduced substantially to the length of the portion of cable 2 having outer covering stripped off. Further, width (in the direction of the row of cables) of relay connector 12 can be reduced substantially to the width of arranged plurality of cables 2.

Fig. 4 is a sectional view showing board-cable connection structure 1. Electrical connection of core 3a of coaxial cables 2 and electrical contact surface 20a (conductor section 21a) may be of any form, and, for example, brazing or an adhesive means such as an anisotropic conductive or non-conductive adhesive for circuit connection may be used. In this embodiment, core 3a of coaxial cable 2 and electrical contact surface 20a (21a) of FPC 13 are connected via solder 50. Ground bar 4 and contact surface 20b (21b) of FPC 13 can also be connected via solder 50. Form of electrical connection of contact surface

20c of FPC 13 and conductor sections 7 of circuit board 8 is also arbitrary, and brazing or an adhesive means such as an anisotropic conductive or non-conductive adhesive for circuit connection may be used. In this embodiment, contact surface 20c of FPC 13 and conductor sections 7 of circuit board 8 is electrically connected via an adhesive for circuit connection (not shown). When non-conductive adhesive is used for electrical connection, a sheet of heat curable adhesive is sandwiched between the upper surface of circuit board 8 and conductor section 21 of FPC 13 with the positional relation between conductor section 21 of FPC 13 and conductor sections 7 of circuit board 8 kept constant, and while heating the adhesive by heater 26 (Fig. 28(b)) disposed under circuit board 8, circuit board 8 and FPC 13 are pressed to each other under specified force to accomplish adhesion. Conditions of temperature and pressure of such hot press bonding are not limited to specific conditions, but depend on composition of the selected adhesive and the like. As an example, when the selected resin has fluidizing temperature of 60-170⁰C and curing temperature of 170-260⁰C, hot press bonding can be carried out at temperature of 150- 23O⁰C, and pressure of 5-200 N/cm2.

As a non-conductive adhesive for circuit connection that can be advantageously used, a film of about 30 μm in thickness containing thermoplastic component and heat curable component in specified ratio that exhibits fluidity at a prescribed temperature and hardens upon further heating, can be mentioned. As an example, phenoxy resin can be used as the thermoplastic resin and epoxy resin can be used as the heat curable component. By adjusting the thermoplastic component and the heat curable component, the heat curable adhesive can be used as a film having repairability. As used herein, "repairability" means that, after a film has been adhered, the film can be released by heating and can be adhered again. Films that can be used as heat curable adhesive are not limited to that of the present embodiment, and various modifications in type of resin or composition may be employed. For example, polycaprolactone modified epoxy resin can be used as a heat curable resin.

Next, a manufacturing method for manufacturing relay connector 12 as a constituent of the board-cable connection structure of the present embodiment will be described. Representative forms of the manufacturing method of relay connector 12 include, but are not limited to, one shown in Fig. 5-Fig. 9. In the method of the present embodiment, as shown in Fig. 5, FPC 13 to be used in relay connector 12 is provided which has conductor sections 21a, 21b, 21c exposed at generally middle portion in a longitudinal direction on the front surface, and other portions covered by insulating resist 27. On the back surface of FPC 13, flat plate 14 formed in generally half the size of the back surface of FPC 13 is disposed. FPC 13 and flat plate 14 are positioned to each other by engaging respective hole sections 16, 17 with positioning pins 18 of a jig. Positioned FPC 13 and flat plate 14 may be fixed by any fixing means, for example by sticking agent or heat curable adhesive. Fig. 6 shows the state in which FPC 13 and the flat plate 14 are adhered.

Then, as shown in Fig. 7, the other half of FPC 13 that is not adhered to flat plate 14 is folded in the shape of U and is fixed to the back surface of flat plate 14. Fig. 8 shows the state in which FPC 13 is adhered to both front and back surfaces of flat plate 14, and conductor sections 21a, 21b, 21c in the longitudinally middle portion of FPC are disposed at one edge of flat plate 14.

Then, as shown in Fig. 9, relay connector 12 is obtained by cutting flat plate 14 at a specified distance apart from the one edge of flat plate 14 so as to include conductor sections 21 disposed at the one edge of flat plate 14. Relay connector 12 thus manufactured has conductor sections 21a, 21b connected to core 3 a of cables 2 and to ground bar 4 connected to cable 2, and has conductor section 21 to be connected to the wiring conductor of circuit board 8 on the back surface. Board-cable connection structure 1 is manufactured by connecting cable set 5 and shield shell 6 to relay connector 12 thus manufactured. Board-cable connection structure 1 thus manufactured is electrically connected to conductor section 7 of circuit board 8. When FPC 13 folded in the shape of U in advance is to be adhered to circuit board 8, it is preferable that curing temperature or melting temperature of adhesive means used in adhesion of FPC 13 to circuit board 8 be lower than melting temperature or softening temperature of adhesive means used in adhesion of cable 2 or ground bar 4 to FPC 13. By selecting respective adhesive means in this manner, adhesion of cable 2 or ground bar 4 to FPC 13 is not affected by the heat applied when board-cable connection structure 1 is adhered to circuit board 8.

Fig. 10 is a view showing a board-cable connection structure according to a second embodiment of the present invention. This embodiment differs from the first embodiment in the construction of relay connector 30. Relay connector 30 according to this embodiment includes PCB 31 having penetrating conductor 32 that penetrates from the front surface to the back surface with wiring conductors 33 electrically connected to core 3 a of coaxial cables 2 on the front surface of PCB 31 and with wiring conductors 33 connected to conductor sections 7 of circuit board 8 on the back surface of PCB 31. PCB 31 serves to function both as FPC 13 and flat plate 14. In the present embodiment, the front surface and the back surface of relay connector 30 is electrically connected via penetrating conductor 32, and therefore, need to fold PCB 31 in the shape of U as in the first embodiment is eliminated. Otherwise, the construction is the same as in the first embodiment, and duplicate explanation is omitted.

Fig. 11 is a view showing a board-cable connection structure according to a third embodiment of the present invention. This embodiment differs from the first embodiment in the construction of relay connector 35. Relay connector 35 according to this embodiment uses plate 36 as shown in Fig. 12. Plate 36 has opening 51 in the middle portion in a longitudinal direction, and has interconnecting section 52 on both sides. Interconnecting section 52 may have a groove (folding section) 53 for folding provided in advance in width direction of plate 36. The portion at which FPC 13 is folded in the shape of U is positioned and disposed relative to opening 51 or groove 53, and after the entire adhering surface is adhered on the surface of plate 36 having a same size with FPC 8, FPC 13 together with plate 36 is folded in the shape of U with generally middle portion in a longitudinal direction of FPC 13 as a fulcrum at a position corresponding to opening 51 of plate 36 to form the relay connector. Folded plates 36 can be fixed to each other by an adhesive or the like. Plate 36 having FPC 13 applied thereto can be trimmed to desired size before folding or after folding. Plate 36 may have, after being folded in the shape of U, both side ends cut off so as not to leave interconnecting section 52. With relay connector 35 of the present embodiment, bending radius of folded FPC 13 in the shape of U can be easily controlled. By providing folding groove 53, folding center of plate 36 can be easily set.

In the embodiment described above, FPC 13 is folded in the shape of U before relay connector 12, 35 are connected to circuit board 8. It is also possible, however, to fold FPC 13 in the shape of U at folding section 2Od (Fig. 15) after the relay connector is connected to circuit board 8. As shown in Fig. 13, relay connector 35A is manufactured in the state in which the half of FPC 13 having conductor section 21c is not folded in the shape of U and is not adhered to plate 14. FPC 13 is fixed at one end thereof to plate 14 with the unfixed portion of FPC 13 projecting forward from the front edge of plate 14. Conductor section 21c of FPC 13 and conductor section 7 of circuit board 8 are adhered to each other by some adhesive means, for example, by hot press bonding using a non- conductive adhesive for circuit connection. Fig. 14 and Fig. 15 are views showing the state in which circuit board 8 is adhered to the outer surface of FPC 13 by hot press bonding. Then, FPC 13 is folded downward in the shape of U with folding section 2Od as a fulcrum, and the back surface of FPC 13 is adhered to the plate by an adhesive or the like. Adhesive means may be disposed on the surface of plate 14 in advance. In this example, when an adhesive for circuit connection is used for hot press bonding, circuit board 8 can be disposed on the underside with FPC 13 placed on top of it to apply heat with heater 26 from the side of FPC 13. In such arrangement, the board-cable connection structure can be easily processed by hot press bonding irrespective of the material and thermal conductivity of circuit board 8. Since circuit board 8 and FPC 13 can be directly sandwiched by heaters or the like, press bonding at higher pressure, or secure press bonding of respective conductor sections 21c to the corresponding conductor sections 7, is facilitated. Since heat at the time of hot press bonding is hard to be conducted to the adhering point of FPC 13 and the cables or the ground bar, selection of respective adhesive means becomes easier.

It is also possible, as shown in Fig. 16, after circuit board 8 is adhered to the outer surface of FPC 13, to fold FPC 13 upward in the shape of U with folding section 2Od as a fulcrum and to fix circuit board 8 to the top surface of shield shell 6. Relay connector 35B in this example can be formed with bending radius of the folding section 2Od larger than the bending radius of relay connector 35A shown in Fig. 15.

As another variant, plate 36 used in the third embodiment can be used as the plate of the relay connector. That is, FPC 13 is adhered to the entire surface of plate 36 in advance, and is connected to circuit board 8 before being folded in the shape of U, and then, FPC 13 together with plate 36 is folded in the shape of U. In these embodiments, the size of FPC 13 connected to circuit board 8 can be trimmed by some known method before or after connection to circuit board 8.

Next, a board-cable connection structure according to a fourth embodiment will be described. As shown in Fig 17, board-cable connection structure 61 according to this embodiment differs from board-cable connection structure 1 according to the first embodiment in that it comprises clamp means 60 for holding the relay connector with FPC 13 folded in the shape of U on circuit board 8. It also differs from the fixation method of relay connector 12, 35A, 35B in that relay connector 65 is fixed to circuit board 8 by clamp means 60. Clamp means 60 includes a pair of base members 62 and cover member 63 which holds both longitudinal ends of relay connector 65 with a pair of base member 62. Like shield shell 6 shown in Fig. 1, cover member 63 can shield the connecting part of relay connector 65, circuit board 8 and cables 2, by covering relay connector 65 between circuit board 8 and it.

As shown in Fig. 18 and Fig. 19, relay connector 65 of this embodiment has long plate 14 and FPC 13 electrically connected to core 3 a of coaxial cable 2. Plate 14 is wider than FPC 13, and both side portions extend in width direction of FPC 13. The extending portions on both sides of plate 14 are adapted to be clamped between a pair of base members 62 and cover member 63. One end of FPC 13 is fixed between plate 14 and upper ground bar 4 by an adhesive (adhesive sheet) or the like. On the side of one end of FPC 13, core 3 a of the coaxial cables 2 are brazed to signal conductor sections 21a exposed on the surface not fixed to plate 14 (see Fig. 19). Upper ground bar 4 is brazed to conductor section 21b for grounding. On the side of the other end of FPC 13, conductor sections 21c are formed to be electrically connected to circuit board 8 by hot press bonding.

Fig. 20 is a view showing the state in which cover member 63 is opened relative to a pair of base members 62 on circuit board 8. In this state, on the side of one end of relay connector 65, long plate 14 is attached to be positioned on cover member 63, and the other end of relay connector 65 is disposed in the space between a pair of base members 62 separated from each other, and conductor section 21c of FPC 13 is adhered to circuit board 8 by hot press bonding. A pair of base members 62 and cover member 63 are formed as separate members, but is interconnected via interconnecting pin 64 to permit opening and closing. In order to keep cover member 63 in closed state relative to a pair of base members 62, the pair of base members 62 and cover member 63 have a lock mechanism as described below.

Forms of a pair of base members 62 and cover member 63 is not especially limited, but may be formed by punching a thin metal sheet with a press and then bending and folding. A pair of base members 62 has a left-right symmetric shape, and individual base member 62 has one end interconnected to interconnecting pin 64, and on the other end, has a pair of upright standing erected pieces 67a, 67b with locking claw 66. On inner erected piece 67b, cut-away section 68 is formed for engaging with plate 14 of relay connector 65 when relay connector 65 is clamped between a pair of base member 62 and cover member 63. Bottom wall 69 is formed flat, and can be used as adhering surface to be fixed to the upper surface of circuit board 8 by an adhesive or the like. Cover member 63 has a pair of arms 70 on both sides in width direction rotatably interconnected to a pair of base members 62. Cover member 63 is also formed with a pair of bent pieces 72a, 72b having locking hole 71 to be engaged with locking claw 66 so as to stand upright relative to upper wall 73. When cover member 63 is closed, the tip of bent pieces 72a, 72b slides down on the inclined surface of locking claw 66 to be locked with inner surface of locking hole 71 to the locking surface of locking claw 66 to thereby hold the locking state of a pair of base members 62 and cover member 63.

Fig. 21 is a sectional view showing the state in which cover member 63 is opened, and Fig. 22 is a sectional view showing the state in which cover member 63 is closed. In the state in which cover member 63 is opened, the both ends of FPC 13 extends in an opposite direction. In the state in which cover member 63 is closed, FPC 13 is folded in the shape of U with the folding section as a fulcrum. When cover member 63 is closed, the form of relay connector 65 is generally the same as relay connector 12 shown in Fig. 4. Thus, in the present embodiment, relay connector 65 in the shape of U can be formed by rotation of cover member 63. Since, in the present embodiment, relay connector 65 is held between a pair of base members 62 and cover member 63, even if unintended pulling force is suddenly applied, relay connector 65 is prevented from separating away from circuit board 8.

Figs. 24-27 are views showing a board-cable connection structure according to a fifth embodiment of the present invention. The board-cable connection structure of this embodiment differs from previous board-cable connection structure 1, 61 in that, unlike the previous embodiments in which a multiplicity of cables 2 are connected to one relay connector 12, 30, 35, 35A, 35B, 65 as described above, a multiplicity of relay connectors are assembled in this embodiment. Relay connector 81A, 81B, 81C of this embodiment has FPC 13 bent and folded not near the edge of plate 14 (see Fig. 1), but at a position some distance apart from the edge of plate 14. Thus, there is a gap between the bent section of FPC 13 and the edge of the plate 14. In this manner, after FPC 13 is connected to circuit board 8 (see Fig. 15, etc.), when FPC 13 is to be bent and folded in the shape of U, cables 2 and plate 14 do not impede the connecting operation of FPC 13 to circuit board 8, and workability is thereby improved. In a variant of this embodiment, FPC 13 may be used without being folded in the shape of U. Fig. 23 is a view showing, for comparison, a multiplicity of cables 2 connected to one relay connector 12. 42 cables 2 are bundled into one unit at generally midway in a longitudinal direction of the relay connector. Cables 2 are bundled in order to facilitate handling of cables 2 in the enclosure. In this example, however, since relay connector 12 is long, it imposes limit to the disposition of circuit components mounted to circuit board

8, and derived cable portion (fan shaped portion) of cables 2 may occupy the mounting space for the circuit components. In addition, larger tension is produced in both sides of cables 2 arranged in a row.

Fig. 24 is a view showing board-circuit connection structure 8OA having two relay connectors 81 A with cable deriving ends 83 opposed to each other. Bundle section (assembly section) 82 that bundles 21 cables 2 derived from cable deriving end 83 of individual relay connector 81 A is situated between the cable deriving ends 83 of two relay connectors 8 IA. Bundle section 82 of this embodiment is shown as an example of assembly section that assembles a multiplicity of cables derived from individual relay connector. Although, in this embodiment, assembly section is shown as a bundle section that bundles cables 2 with a bundling member, the form of the assembly section is not limited to this. Other examples may include a tape wound section that winds a multiplicity of cables with a tape, a bundle section bundled in other method, and a closely assembled section in which a multiplicity of cables are closely disposed without any bundling means. An assembly section may include, in addition to the portion of closely assembled multiplicity of cables, a portion in which the multiplicity of cables expands in the shape of fan adjacent to the portion of closely assembled multiplicity of cables.

Although bundled cables 2 in the example shown are directed downward, they may be directed in any direction. In this example, since longitudinal dimension of individual relay connector 81 A is about 1/2 of that of relay connector 12 shown in Fig. 23, the degree of freedom for disposing circuit components mounted on circuit board 8 is increased. Since the expanding width W of the derived cable portion of cables 2 derived from relay connector 81 A becomes smaller and the derived length L becomes shorter, mounting space for circuit components can be increased. Further, tension produced on both sides of cables 2 can be reduced.

Fig. 25 is a view showing board-cable connection structure 80B having four relay connectors 8 IB disposed with respective cable derivation ends 83 opposed to each other, as a variant of board-cable connection structure 8OA of Fig. 24. Bundle section 82 that bundles 11 cables each extracted from the cable derivation end of individual relay connectors 8 IB is situated in the region surrounded by four relay connectors 8 IB. In other words, four relay connectors 8 IB are disposed around bundle section 82 in a radiation pattern. Bundled cables 2 can be directed in any direction. In this example, longitudinal dimension of individual relay connectors 8 IB is about 1/4 of that of the relay connector shown in Fig. 23, so that the degree of freedom for disposing circuit components mounted on circuit board 8 is increased, and mounting space for circuit components can be increased. Tension produced on both sides of cables 2 can be reduced further. Fig. 26 is a view showing board-cable connection structure 8OC having eight relay connectors 81C disposed with respective cable derivation ends 83 opposed to each other, as a variant of board-cable connection structure 8OA of Fig. 24. Two relay connectors 81C are disposed on one FPC 13, and two relay connectors 81C are disposed such that respective cable derivation directions intersect each other. Bundle section 82 that bundles cables 2 derived from cable derivation end 83 of individual relay connectors 81C into one bundle is situated in the region surrounded by eight relay connectors 81C. In other words, eight relay connectors 81C are disposed around bundle section 82 in a radiation pattern. Bundled cables 2 can be directed in any direction. In this example, longitudinal dimension of individual relay connectors 81C is about 1/8 of that of the relay connector shown in Fig. 23, so that the degree of freedom for disposing circuit components mounted on circuit board 8 is increased, and mounting space for circuit components can be increased. Uniform tension is produced in cables 2 derived from individual relay connectors 81C, and large tension produced only on both sides can be avoided.

Fig. 27 is an enlarged view of a part of relay connector 81C shown in Fig. 26, showing the state of connection of core 3 a of the cable 2 to conductor section 21c of FPC

13. FPC 13 has the end connected to cables 2 formed in wide width, and the conductor section is wired in two branches. Both branches of the conductor section have each five cables 2 connected thereto. Individual relay connector 81C has five cables 2 arranged in a row, a plate (not shown) and FPC with one end fixed to the plate. With such construction, while tension produced in cables 2 is reduced, two relay connectors 81C are disposed to one FPC, so that handling workability can be improved. Core 3a and conductor section 21c are connected by brazing or the like. If large tension is produced in cable 2, the tension is exerted on the connecting part of core 3a and conductor section 21c and may break it. However, in board-cable connection structure 8OC of the present embodiment having assembled relay connector 81C, tension produced in coaxial cables 2 when bundling a multiplicity of cables 2 can be reduced, and reliability of electrical connection of cable 2 and FPC 13 can be increased.

The board-cable connection structure and the manufacturing method of the relay connector and the fixation method of the relay connector have been described in the foregoing. The present invention, however, is not limited to the embodiments disclosed above, but may be implemented in various other forms. Board-cable connection structure 1 in the present disclosure is shown in the form having board-cable connection structure 1 superposed on circuit board 8. However, it is also possible to arrange circuit board 8 and board-cable connection structure 1 in a longitudinal direction, as shown in complete form in Fig. 28(c). When circuit board 8 and board-cable connection structure 1 are arranged in a longitudinal direction, as shown in Fig. 28(a), (b), while FPC 13 connected to cable set and extending straight is heated from above with heater 26, pressure can be applied so as to electrically connect FPC 13 to circuit board 8. Fig. 28(c) shows the state in which, in order not to produce tension in FPC 13 between board-cable connection structure 1 and circuit board 8, board-cable connection structure 1 is fixed to the installation site, for example between a pair of protrusions 41a, 41b provided on enclosure 40 of a mobile phone. With this example, since cables 2 derived from board-cable connection structure 1 are not wired circuit board 8, interference of coaxial cables 2 with the devices on circuit board 8 can be avoided, and board-cable connection structure 1 can be formed smaller in height. Such arrangement is especially suitable for the circuit board to be stacked in plural layers, wherein there is not sufficient space available above circuit board 8. If, as shown in Fig. 28(c), FPC 13 is kept flexed between circuit board 8 and plate 14, tension produced in FPC 13 and the connecting part of FPC 13 and circuit board 8 or cables 2 by thermal expansion of enclosure 40 can be eliminated.

In the manufacturing method of the board-cable connection structure disclosed herein, FPC 13 is bent and folded in the shape of U from the front surface side to the back surface side of plate 14 in one direction, or is bent and folded together with plate 14 in the shape of U in one direction. However, it is also possible, in view of the case where the board-cable connection structure according to the present invention is to be mounted to a specific type of mobile phone, to bend FPC 13 temporarily to the upper side in the shape of U, as shown in Fig. 29(a) to (c) such that the outer surface of FPC 13, and then to turn FPC 13 toward plate 14 (underside) in the shape of U, as shown in 29(d). The reason why FPC 13 is temporarily turned toward the upper side in the shape of U is that, as shown in

Fig. 29(c), board-cable connection structure 1 together with coaxial cable 2 has to be passed through the inner space of flexible hinge section 45 which connects the upper and lower enclosures. With this example, when board-cable connection structure 1 is passed through the inner space of flexible hinge section 45, conductor section 21c exposed on the outer surface of FPC 13 is prevented from being broken by the contact with the inner wall of hinge section 25, and reliability of electrical connection can be thereby improved.

Other forms of the cables to be connected to the relay connector 12, 30, 35, 35A, 35B, 65, 81A-81C may include the form of hybrid cable type which combines small size coaxial cables 2 with optical fiber 24. In this case, photoelectric conversion modules 25 having optical fibers 24 connected thereto may be surface-mounted, as shown in Fig. 30.

Claims

1. A board-cable connection structure comprising: a multiplicity of cables arranged in a row; and a relay connector having a plate and a FPC of which at least one end of a first surface is fixed to a front surface of said plate; wherein said FPC has a first electrical contact surface comprising first conductor sections electrically connected to said multiplicity of cables on one end side of a second surface, a second electrical contact surface comprising exposed second conductor sections connected to a circuit board on the other end side of said second surface, and a bent section bent and folded in a shape of U between said one end side and said the other end side of said second surface.

2. A board-cable connection structure comprising: a multiplicity of cables arranged in a row; and a relay connector having a plate and a FPC folded and fixed to said plate on a front surface and a back surface thereof in a shape of U; wherein said relay connector has a first electrical contact surface comprising first conductor sections electrically connected to said multiplicity of cables on one surface, and a second electrical contact surface comprising exposed second conductor sections connected to a circuit board on the other surface.

3. A board-cable connection structure comprising: a multiplicity of cables arranged in a row; and a multiplicity of relay connectors connected to a end of said multiplicity of cables; wherein said multiplicity of relay connectors are arranged in a radial pattern around an assembly section assembling said multiplicity of cables derived from said multiplicity of relay connectors with a derived cable end of said multiplicity of relay connectors facing inward.

4. A board-cable connection structure according to claim 3, wherein said relay connectors have a plate and a FPC bent and folded in a shape of U and fixed to said plate on the front surface and the back surface thereof, and wherein said relay connectors have a first electrical contact surface comprising first conductor sections electrically connected to said cables on one surface, and a second electrical contact surface comprising exposed second conductor sections connected to a circuit board on the other surface.

5. A board-cable connection structure according to claim 2 or 4, wherein said FPC together with said plate is bent and folded in the shape of U.

6. A board-cable connection structure according to any one of claims 1 to 3, further comprising clamp means provided on said circuit board for holding said FPC folded in the shape of U.

7. A board-cable connection structure according to claim 6, wherein said clamp means comprises a base member which has a locking section and is fixed to said circuit board, and a cover member which has a locked section to be engaged with said locking section and is interconnected to said base member so as to permit opening and closing, and wherein, with one end of said FPC attached to a inner surface of said cover member and with the other end of said FPC fixed to said circuit board, said FPC is bent and folded in the shape of U by closing said cover member to be locked to said base member.

8. A manufacturing method for manufacturing a relay connector for relaying and connecting a multiplicity of cables to a circuit board, said method comprising: providing a FPC which has a multiplicity of conductor sections arranged at a specified interval on a front surface and has a fixing surface on a back surface; positioning said FPC to a plate to which the FPC is to be fixed with said conductor sections of said FPC facing outward, and fixing said fixing surface on one end side of said FPC to said front surface of said plate; and bending and folding the other end side of said FPC not fixed to said plate with a portion positioned in a vicinity of an edge of said plate as a fulcrum to said back surface of said plate in the shape of U, and fixing said fixing surface of the other end side of said FPC to said back surface of said plate.

9. A fixation method for fixing a relay connector, said method comprising: electrically connecting said second conductor section of said FPC of the relay connector according to claim 1 to a conductor section of a circuit board, and thereafter, bending and folding one end side of said FPC with generally middle portion of said FPC as a fulcrum in the shape of U and fixing it to said back surface or said front surface of said plate.

10. A fixation method for fixing a relay connector, said method comprising: fixing a base member having a cover member interconnected to a circuit board so as to permit opening and closing; disposing one end side of said FPC of said relay connector according to claim 1 on an inner surface of said opened cover member; electrically connecting said second conductor section on the other end side of said FPC to a conductor section of said circuit board; bending and folding one end side of said FPC in the shape of U by rotating said cover member in closing direction with generally middle portion of said

FPC as a fulcrum; and locking said cover member to said base member to thereby hold said FPC folded in the shape of U.