JP2001068907A - FPC cable and FPC cable connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize signal lines of a cable at a contact section that are arranged with high density. SOLUTION: An FPC(flexible printed circuit) cable is configured such that a ground layer 5 is placed to one side of a dielectric layer 7, a plurality of signal lines 2 is placed on the other side, and a ground line 6 is interposed among the signal lines 2. Each ground line 6 interposed among the signal lines 2 is terminated before it reaches a contact section 2a where the signal line at a cable end is exposed, and each ground line 6 is connected to the ground layer 5 via an electrically conductive inter-layer connection member 9 penetrated through the dielectric layer 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FPC (flexible printing circuit) having a microstrip line structure.
t) Cable and SMT (surface mount technology) for connecting this FPC cable to a printed circuit board
Type of FPC cable connector.

[0002]

2. Description of the Related Art Connection between a liquid crystal display panel and a motherboard in a notebook personal computer, connection between motherboards,
Further, for connection between daughter boards, high-speed signal transmission and EMI (electro magnetic interferenc) are required.
e) Since countermeasures are required, multi-core coaxial cables and FPC cables having a microstrip line structure are mainly used.

[0003] A multi-core coaxial cable has excellent EMI characteristics due to its shielding property. However, when connecting to a connector, one or one multi-core coaxial cable must be connected. There is a problem that it takes a lot of time to connect and the work efficiency is poor. Also, multi-core coaxial cable is
There is also the problem that prices are generally high.

On the other hand, FIG. 7 and FIG. 8 show a prior art concerning an FPC cable and a connector for the FPC cable.

[0007] As shown in FIGS. 7 and 8, the FPC cable 100 has a microstrip line structure in which a central layer is a ground G and signal layers are formed on both sides thereof. Is assigned, thereby reducing the amount of crosstalk.

[0006] The connector 150 is connected to the FPC cable 100.
Of the FPC cables 100, so that the contact portions are arranged in two rows in the housing.

[0007]

In the prior art shown in FIGS. 7 and 8, a ground line G is provided on both sides of a signal line S.
, The crosstalk can be reduced, but these ground lines are
Since the signal line S extends to the contact portion of the electrode pad 101, that is, the electrode pad 101, there is a problem that the signal line S cannot be mounted at a sufficiently high density in the electrode pad portion 101 where the signal line S is exposed.

In this prior art, the connector 150
In particular, no countermeasures against noise and impedance matching are taken on the side, which is insufficient in terms of noise and impedance matching.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide an FPC cable in which signal lines can be arranged at a high density at a contact portion of the cable.

Further, the present invention reduces the electromagnetic noise and the crosstalk, and realizes a suitable impedance matching.
It is an object of the present invention to provide a PC cable connector.

[0011]

According to the first aspect of the present invention, a ground layer is disposed on one side of a dielectric layer, and a plurality of signal lines are disposed on the other side. FPC with ground line interposed between these signal lines
In the cable, each ground line interposed between the signal lines is terminated before a contact portion of the cable end where the signal line is exposed, and each ground line is connected to a conductive interlayer penetrating through the dielectric layer. It is connected to the ground layer via a material.

According to a second aspect of the present invention, in the first aspect of the invention, a conductive reinforcing plate is laminated on the surface of the ground layer at the end of the cable.

According to a third aspect of the present invention, in the first aspect of the invention, each of the signal lines is terminated at an interval from an end of the cable, and a dielectric on the signal line side at the end of the cable is provided. A ground layer extending in the width direction of the cable is arranged on the layer, and the ground layer is connected to the ground layer via a plurality of conductive interlayer connecting members penetrating the dielectric layer. .

According to a fourth aspect of the present invention, a ground layer disposed on one side of the dielectric layer, a plurality of signal lines disposed on the other side of the dielectric layer, and a plurality of signal lines interposed between the signal lines. A plurality of ground lines terminated in front of the contact portion where the signal line at the cable end is exposed, and a conductive interlayer connecting material that penetrates the dielectric layer and connects each ground line to the ground layer. An FPC cable connector for electrically connecting an FPC cable having a conductive reinforcing plate laminated on a surface of a ground layer at a cable end to a printed circuit board, comprising: an insulating connector housing; A contact portion that contacts the signal line of the FPC cable, and a gap between the end portion and the contact portion in a direction substantially along the printed board with a gap from the printed board. A plurality of signal terminals, each of which has a extending portion which is supported by the connector housing to standing,
A flat contact shell having a contact portion supported by the connector housing so as to cover above the plurality of signal terminals and contacting a conductive reinforcing plate of the cable; and the printed circuit board extending from the contact shell. A conductive shell body having a ground terminal portion that supports the connector housing so as to be connected to the ground. The FPC cable is connected to the signal line in a space between the contact shell and the plurality of signal terminals. FP by inserting the printed circuit board with the side facing
The C cable and the connector are connected.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the line width of the extending portion is wider than the line width of the end portion of each of the signal terminals fixed to the printed circuit board. Features.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, the FPC cable will be described with reference to FIGS.

FIG. 1 is a perspective view showing the structure of the distal end of the FPC cable 1, FIG. 2 (a) is a plan view showing the entire cable 1, and FIG. 2 (b) is a side view thereof. FIG.
3A is a plan view showing the structure of the tip of the FPC cable (portion indicated by arrow A in FIG. 2), FIG. 3B is a side view thereof, and FIG. 3C is XX in FIG. 3A. FIG. 3D is a sectional view taken along line YY of FIG. 3A.

As shown in FIG. 2, in the cable 1, a plurality of fine signal lines 2 extending along the longitudinal direction of the cable 1 are arranged in parallel in the width direction of the cable 1. A conductive metal reinforcing plate 3 is attached to the back surface of both ends of the cable 1. The reinforcing plate 3 is formed, for example, by applying gold plating to the front and back surfaces of a copper plate. A contact portion (cover lay opening) 4 where the signal line 2 on the surface of the tip of the cable 1 is exposed;
A cover coat material (not shown) made of a thermosetting resist, a polyimide film, or the like is formed on the front and back surfaces of the cable 1 excluding a part of the back surface to which the reinforcing plate 3 is attached.
Is coated.

Next, the laminated structure of the cable 1 and the planar arrangement of the distal end thereof will be described with reference to FIGS.

The cable 1 has a microstrip line structure, and basically has a plate-like ground layer 5 disposed on the entire back surface, a plurality of signal lines 2 and a plurality of front surface ground lines located on the front surface. 6 and a dielectric layer 7 interposed therebetween. As described above, the front and back surfaces are covered with a cover coat material (not shown). A metal reinforcing plate 3 is directly adhered to the ground layer 5 with a conductive adhesive 8 (FIG. 1) or the like at both ends on the back surface of the cable 1. The ground layer 5, the surface ground line 6, and the signal line 2 are formed of, for example, copper foil.
The surface of the contact portion 2a of the signal line 2 (coverlay opening 4 (see FIG. 2)) is plated with Au flash. The dielectric layer 7 is made of, for example, a liquid crystal polymer.

The plurality of signal lines 2 disposed on the surface side of the cable 1 are formed such that the width of the other central portion 2b is smaller than the width of the contact portions 2a at both ends. And
The surface ground line 6 is arranged between each of the narrower signal line central portions 2b. That is, the surface ground line 6
Exists only between the central portions 2b of the signal lines 2 and terminates before the wide contact portion 2a.

For example, the contact portion 2 at the tip of the signal line 2
The width of a is 0.28 μm, the width of the central narrow portion 2b is 0.11 μm, and the width of the surface ground line 6 is 0.28 μm.
m.

The tip of each surface ground line 6 is connected to the ground layer 5 on the back surface by a conical bump 9 made of a conductive material, and both are electrically connected. The bump 9 functions as an interlayer connecting material similarly to the through hole, and is formed of, for example, an Ag-based conductive resin. Note that such a method of connecting the front surface conductor layer and the back surface conductor layer sandwiching the dielectric layer 7 by the conductive bumps 9 is the same as the conventional method using a through hole to form a hole. There is an advantage that the steps, the plating step, the plating stripping step, and the like can be omitted, and the manufacturing steps can be simplified.

In the method using the bumps, the back conductor layer and the front conductor layer from which the bumps 9 are projected are thermocompression-bonded with the dielectric layer interposed therebetween, so that the dielectric layers are penetrated by the bumps 9 and the back conductor layer is formed. The front surface conductor layer is connected to the front surface conductor layer by a bump 9, and thereafter, a required back surface conductor layer pattern or a front surface conductor layer pattern is formed through a resist coating, etching, and resist stripping steps.

Further, a surface ground portion 10 made of a copper foil material is formed at the foremost portion of the surface of the cable 1 to protect the signal line 2a. Are connected to the back surface ground layer 5 by the bumps 11. These bumps 11 are located at a central position between the signal lines 2a in the width direction of the cable 1, so that the space between the signal lines is reliably dropped to the ground.

According to this cable structure, each ground wire 6 interposed between the signal wires 2 is terminated before the contact portion 2a where the signal wire at the cable end is exposed. The signal line density at the contact portion can be remarkably improved as compared with the related art. Also,
Since the signal line 2 is sandwiched between the ground lines 6 and these ground lines 6 are connected to the ground layer 5 on the back surface via the bumps 9, crosstalk and electromagnetic noise can be reduced.

Also, since the conductive reinforcing plate 3 is laminated on the surface of the ground layer 5 at the end of the cable, the end of the cable can be reinforced and the conductive reinforcing plate 3 can be connected to a connector described later. Since the ground connection can be made via the reinforcing plate 3 and the ground can be connected with a large connection area, it contributes to the reduction of electromagnetic noise.

Further, each signal line 2 is terminated at an interval from the end of the cable, and a ground portion 10 extending in the width direction of the cable is arranged at the end of the cable. Is connected to the ground layer 5 on the back surface, the signal line 2 can be protected, and the signal line of the contact portion 2a where the signal line 2 is exposed can be reliably grounded.

Next, the configuration of the connector 20 for connecting the above-described cable 1 and the manner of connection between the connector 20 and the cable 1 will be described with reference to FIGS.

FIGS. 4A and 4B show the appearance of the connector 20, in which FIG. 4A is a plan view, FIG. 4B is a side view, and FIG. 4C is a rear view. FIG. 5 is a partially broken plan view showing the internal structure of a part of the connector 20. FIG. 6 shows a connection state between the connector 20 and the cable 1, for example, BB in FIG.
It is sectional drawing.

In these figures, a connector 20 has a connector housing 21 integrally formed of an insulating material such as a resin, and a shell 30 formed of an integrally formed metal having a ground terminal portion 31 and a contact shell portion 32.
And a plurality of signal terminals 40 arranged in parallel.

The cable 1 is, as shown in FIG.
The signal terminal 40 of the connector 20 is inserted from the exposed front side and is engaged in the connector 20 as shown in FIG.

Two slits 22 are formed on both sides of the connector housing 21, and two slits 22 extend downward from both sides of the contact shell portion 32 of the shell 30 in these slits 22. The part 33 is engaged. Two of the four joints 33 have:
Dip terminals 34 penetrating through holes in printed circuit board 50 extend further downward. The dip terminal 34 is connected to the ground of the printed circuit board 50.

A slit 25 (FIGS. 4 (c) and 6) is also formed in the center of the rear side of the connector housing 21, and this slit 25 has a substantially L-shape extending downward from the rear of the contact shell 32. Shaped joint 35 is engaged.

The connector housing 21 has a pair of upper and lower signal terminal support portions 23a and 23b for holding and fixing the plurality of signal terminals 40 vertically. An opening 24 is formed in each of the signal terminal support portions 23a and 23b where the signal terminal 40 is located. In order to form the openings 24 corresponding to the signal lines arranged at high density,
The positions of the adjacent openings 24 are shifted. These openings 24 are provided in the signal terminal support portions 23 of the connector housing 21.
It is provided for inserting a slide pin for holding the extension 43 of the signal terminal 40 at the time of molding a and 23b.

The contact shell portion 32 of the shell 30
As shown in FIG. 6, a convex portion 33 functioning as a guide body of the cable 1 or a contact with the metal reinforcing plate 3 of the cable 1 is provided on a lower surface side of the connector 20. A plurality of convex portions 34 functioning as contacts with one metal reinforcing plate 3 are formed. The upper surface side of the contact shell portion 32 corresponding to the convex portion 33 is a concave portion 35, and the upper surface side of the contact shell portion 32 corresponding to the convex portion 34 is a concave portion 36.

The convex portion 33 is provided with the concave portion 3 shown in FIG. 4 or FIG.
As can be seen from 5, the signal terminals 40 are formed continuously along the arrangement direction. On the other hand, the protrusions 34 are small-diameter protrusions, as can be seen from the recesses 36 shown in FIG. 4 or FIG. 5, and are distributed along the arrangement direction of the signal terminals 40.

Ground terminal 31 of connector shell 30
Functions also as a leg for sitting on the printed circuit board 50, and its surface area is made as large as possible to prevent noise. The ground terminal 31 is a printed circuit board 50
, And as shown in FIG.
Is connected to the back surface ground 52 of the printed circuit board 50 through the through hole 51.

As shown in FIG. 6, each signal terminal 40 has an end 41 which is fixed by soldering to a contact pad of a printed circuit board 50, a contact portion 42 which contacts the signal line 2 a of the FPC cable 1, and a printed circuit board 50. The connector housing 20 has an extending portion 43 supported by the signal terminal supporting portions 23a and 23b so as to extend in a direction substantially along the surface. The distal end side from the extending portion 43 has a substantially rectangular shape, and makes contact with the contact portion 2a of the signal line of the inserted cable 1 using elasticity.

As shown in FIG. 5, each signal terminal 40 has an extended portion 43 and a contact portion 42 which are smaller than the line width of the end portion 41.
Line width is increased. That is, since the ground line 6 does not exist between the signal lines, the capacitance of the contact portion 2a of the cable is lower than that of the portion where the ground line 6 exists. Increasing the width of the extending portion 43 and the contact portion 42 of the line 40 compensates for the capacitance, whereby
The characteristic impedance from the connector entrance to the exit of the signal line is set to be the same as the characteristic impedance of the cable of 50 ohms.

In this connector structure, by adjusting the distance between the extending portion 43 of the signal terminal 40 and the surface ground 54 of the printed circuit board 50, the capacitance can be adjusted for the characteristic impedance 50 of 50 ohms. To do.

According to the connector 20, as shown in FIG. 6, the FPC cable 1 is formed through the opening 60 formed between the contact shell 32 of the shell 30 and the signal terminal supporting portions 23a and 23b of the connector housing 21. Insert When the FPC cable 1 is inserted, the distal end of the cable 1 is engaged with the connector 20 in the space 61 between the signal terminal 40 and the contact shell 32. When the FPC cable 1 and the connector 20 are engaged, the metal reinforcing plate 3 on the back surface of the cable 1 comes into contact with the plurality of convex contacts 34 of the contact shell 32, and the signal line contact portion 2a on the surface of the cable 1 makes a signal. It contacts the contact part 42 of the terminal 40. As a result, the signal line 2 on the surface of the cable 1 is connected to the contact pad 53 of the printed wiring board 50 via the signal terminal 40. On the other hand, cable 1
Is connected to the ground of the printed circuit board 50 via the metal reinforcing plate 3, the contact shell portion 32 and the ground terminal portion 31.

As described above, according to this connector structure, the metal shell 30 is disposed on the connector 20 so as to cover the signal terminals 40, and the ground layer 5 of the cable 1 is connected to the conductive reinforcing plate 3, the contact shell 32, Since the ground is dropped to the ground of the printed circuit board 50 via the ground terminal section 31, it is possible to connect to the ground of the printed circuit board 50 with a large connection area, thereby reducing electromagnetic noise and crosstalk. .

The cables and connectors of the present invention can be used for peripheral devices such as personal computers, printers, displays, FDDs, HDDs, memory cards, mobile phones, automobile navigation devices, video cameras,
The present invention can be applied to wiring boards used for devices such as CD players, semiconductor package substrates, MCM substrates, and other fields such as automotive and satellite devices.

[0046]

According to the first aspect of the present invention, each ground line interposed between the signal lines is terminated before the contact portion of the cable end where the signal line is exposed, and each ground line is connected to the dielectric layer. Is connected to the ground layer via a conductive interlayer connecting material penetrating through the wire, so that crosstalk can be reduced and the signal line density at the contact portion at the end of the cable can be significantly improved. .

According to the second aspect of the present invention, the conductive reinforcing plate is laminated on the surface of the ground layer at the end of the cable, so that the end of the cable can be reinforced and the conductive reinforcing plate can be connected to the connector. The ground connection can be made via the reinforcing plate, and the ground can be connected with a large connection area, thereby contributing to a reduction in electromagnetic noise.

According to the third aspect of the invention, each signal line is terminated at an interval from an end of the cable, and the signal line is placed on the dielectric layer on the signal line side on the end of the cable in the width direction of the cable. And a ground layer extending over the dielectric layer, and the ground layer is connected to the ground layer through a plurality of conductive interlayer connecting members penetrating the dielectric layer. The space between the signal lines of the contact portion where the signal lines are exposed can be reliably dropped to the ground.

According to the fourth aspect of the present invention, the connector is provided with a contact shell so as to cover above the signal terminal, and the ground layer of the cable is connected to the ground of the printed circuit board via the conductive reinforcing plate, the contact shell and the ground terminal portion. As a result, it is possible to connect to the ground with a large connection area, which contributes to a reduction in electromagnetic noise.

According to the fifth aspect of the present invention, since the line width of the extending portion is made wider than the line width of the end portion of each signal terminal fixed to the printed circuit board, a ground line exists between the signal lines. The decrease in capacitance at the contact portion of the FPC cable due to the absence of the cable is compensated for by increasing the line width of the extending portion, whereby the connector has the same characteristic impedance as that of the cable in the connector. A connect structure for impedance matching can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an end structure of an embodiment of an FPC cable according to the present invention.

FIG. 2 is a plan view showing an entire embodiment of an FPC cable according to the present invention.

FIG. 3 is a diagram showing a part of an embodiment of an FPC cable according to the present invention.

FIG. 4 is a three-view drawing showing an embodiment of an FPC cable connector according to the present invention.

FIG. 5 is a partially broken plan view showing an embodiment of the FPC cable connector according to the present invention.

FIG. 6 is a partially broken plan view showing an embodiment of the FPC cable connector according to the present invention.

FIG. 7 is a perspective view showing a conventional technique.

FIG. 8 is a sectional view showing a conventional FPC cable.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 FPC cable 2 Signal line 3 Reinforcement plate 4 Coverlay opening 5 Ground layer 6 Surface ground line 7 Dielectric layer 8 Adhesive 9 Bump 10 Surface ground part 11 Bump 20 Connector 21 Connector housing 22 Slit 30 Shell 31 Ground terminal part 32 Contact shell 40 Signal terminal 41 End part 42 Contact part 43 Extension part 50 Printed circuit board

Claims (5)

[Claims] 1. An FPC cable in which a ground layer is disposed on one side of a dielectric layer, a plurality of signal lines are disposed on the other side, and a ground line is interposed between the signal lines. Terminate each ground wire interposed between the wires before the contact portion where the signal wire at the end of the cable is exposed,
An FPC cable, wherein each of the ground lines is connected to the ground layer via a conductive interlayer connecting material penetrating the dielectric layer. 2. The FPC cable according to claim 1, wherein a conductive reinforcing plate is laminated on the surface of the ground layer at the end of the cable. 3. The signal line is terminated at an interval from an end of the cable, and extends on the dielectric layer on the signal line side on the end of the cable in a width direction of the cable. 2. The FPC cable according to claim 1, wherein a ground layer is provided, and the ground layer is connected to the ground layer via a plurality of conductive interlayer connecting members penetrating the dielectric layer. 4. A ground layer disposed on one side of the dielectric layer, a plurality of signal lines disposed on the other side of the dielectric layer, and a signal at a cable end interposed between the signal lines. A plurality of ground lines terminated before the exposed contact portions; a conductive interlayer connecting member penetrating the dielectric layer and connecting each ground line to the ground layer; and the cable end portion. An FPC cable connector for electrically connecting an FPC cable having a conductive reinforcing plate laminated on a surface of a ground layer to a printed circuit board, comprising: an insulating connector housing; and an end fixed to the printed circuit board. A contact portion for contacting the signal line of the FPC cable, and a contact portion extending between the end portion and the contact portion in a direction substantially along the printed board with a gap from the printed board. A plurality of signal terminals each having an extending portion supported by the connector housing; and a contact portion supported by the connector housing so as to cover above the plurality of signal terminals and contacting a conductive reinforcing plate of the cable. A conductive shell body having a plate-shaped contact shell and a ground terminal portion extending from the contact shell and supporting the connector housing so as to be connected to the ground of the printed circuit board. The FPC cable and the connector are connected by inserting the FPC cable into a space between the shell and the plurality of signal terminals with its signal line side facing the printed circuit board. F
Connector for PC cable. 5. The FPC cable connector according to claim 4, wherein the line width of the extending portion is wider than the line width of an end portion of each of the signal terminals fixed to the printed circuit board. .