JP2010040929A - Electronic equipment and flexible printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible printed circuit board that is manufactured at low cost and enhanced in bending resistance characteristics (slide resistance characteristics). <P>SOLUTION: A flat wiring portion S2 is formed to be freely bent on the whole. Slits (cutting lines) 27 which extend in a length direction L are formed at positions where the flexible printed circuit board 20 is divided into, for example, three in a width direction W. With the slits 27, the flat wiring portion S2 has a plurality of divided wiring portions S21, S22 and S23 each divided into a prescribed number of conductive layers 22, among many conductive layers 22. Further, the flat wiring portion S2 comprises: an inclined wiring portion D1 extending having its width direction w1 inclined at a prescribed angle θ1 to a width direction w2 of connector portions S1; and twist portions D2 connecting the inclined wiring portion D1 and connector portions S1 at both ends of the inclined wiring portion D1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electronic device in which a plurality of housings having circuits are attached so as to be relatively movable, and circuits in these housings are electrically connected by a flexible printed wiring board, and between the housings of the electronic devices. The present invention relates to a flexible printed wiring board used for wiring.

  In recent years, electronic devices typified by mobile phones have been rapidly reduced in size, weight and functionality. A flexible printed wiring board (hereinafter referred to as FPC) is used as an internal wiring material of such a mobile phone.

  In order to achieve both convenience during a call and portability when not in use (standby), for example, a mobile phone has, for example, a first case with a display screen and a second case with an operation button. The mainstream is composed of a body and these two casings are engaged so that they can be bent, rotated, slid, and the like. And in order to electrically connect (wiring) between these some housing | casings, the flexible printed wiring board is used suitably.

  Among such mobile phones, recently, a mobile phone of a type in which two casings slide in parallel with each other is being used. In a slide-type mobile phone, the overall length of the housing changes greatly before and after the slide, so when wiring between two housings, the flexible printed wiring board is nearly U-shaped in the thickness direction of the housing. It is bent and accommodated, and an extra length corresponding to the change in the overall length of the housing before and after the slide is secured.

  However, if the flexible printed wiring board is bent in a U-shape nearly 180 ° in the thickness direction of the housing and the movement (sliding) of the bent portion is repeated each time the housing is slid, for example from copper foil There was a concern that the conductive layer of the formed flexible printed wiring board was broken or peeled off due to fatigue, resulting in poor conduction. In particular, with the progress of thinning of cellular phones in recent years, there has been a concern that the bending radius of the bent portion of the flexible printed wiring board becomes smaller and excessive bending stress is concentrated on the flexible printed wiring board.

In order to improve the bending resistance (sliding resistance) of such a flexible printed wiring board, for example, Patent Document 1 describes a flexible printed wiring board in which a conductive layer is formed of a copper foil having a specific crystal structure. ing.
For example, Patent Document 2 describes a flexible printed wiring board in which a conductive layer is formed of a high-purity copper foil.
JP 2000-151052 A JP 2001-168480 A

  However, the flexible printed wiring boards described in Patent Document 1 and Patent Document 2 described above all use a copper foil having a specific crystal structure, a high-purity copper foil, or the like as the conductive layer. However, there is a problem that the manufacturing cost increases because a special film forming process is required for forming the conductive layer on the flexible substrate.

  The present invention has been made in view of the above circumstances, and even if a plurality of cases that are movably engaged with each other are repeatedly operated such as sliding, bending, and rotating, the continuity failure of the flexible printed wiring board is prevented. It is an object to provide an electronic device that does not cause a problem.

  Another object of the present invention is to provide a flexible printed wiring board that can be manufactured at low cost and has improved bending resistance (sliding resistance).

The electronic device according to claim 1 of the present invention is an electronic device in which a plurality of housings having circuits are engaged so as to be relatively movable, and the circuits of these housings are electrically connected by a flexible printed wiring board. The flexible printed wiring board includes a strip-like flexible flexible board having a predetermined width and length, and elongates along the length direction of the flexible board, and has a predetermined width with each other along the width direction. A flat wiring part having at least a large number of conductive layers arranged in parallel at intervals, and formed at both ends of the flat wiring part, each comprising a flat connector part electrically connected to the circuit, The flat wiring portion has a predetermined number of conductive layers among the plurality of conductive layers by slits formed in the flexible substrate along a length direction of the flexible substrate. Each of the divided wiring portions, and each of the divided wiring portions includes a slanted wiring portion that extends at a predetermined angle with respect to a width direction of the connector portion; It consists of the twist part which connects this inclination wiring part and the said connector part at both ends, It is characterized by the above-mentioned.
The electronic device according to a second aspect of the present invention is the electronic device according to the first aspect, wherein the inclined wiring portion has a width direction substantially perpendicular to a width direction of the connector portion.
An electronic apparatus according to a third aspect of the present invention is characterized in that in the first or second aspect, the electronic apparatus further includes a bundling means for bundling the plurality of inclined wiring portions and stacking them in the thickness direction.
According to a fourth aspect of the present invention, in the electronic device according to any one of the first to third aspects, the inclined wiring portion is bent along the moving surface of the casing.
According to a fifth aspect of the present invention, in the electronic device according to the fourth aspect, the inclined wiring portion is arranged so as to be bent in a U shape along the moving surface of the casing.
The electronic device according to a sixth aspect of the present invention is the electronic device according to any one of the first to fifth aspects, wherein the plurality of housings are slidable with respect to the first housing and the first housing. It consists of the attached 2nd housing | casing, It is characterized by the above-mentioned.
The flexible printed wiring board according to claim 7 of the present invention is a strip-like flexible flexible board having a predetermined width and length, elongates along the length direction of the flexible board, and extends along the width direction. A flexible printed wiring board comprising at least a flat wiring portion having at least a plurality of conductive layers arranged in parallel with each other at a predetermined interval, and flat connector portions formed at both ends of the flat wiring portion, respectively. The flat wiring portion is divided into a predetermined number of conductive layers among the multiple conductive layers by a slit formed in the flexible substrate along a length direction of the flexible substrate. Inclined wiring comprising a divided wiring portion, the divided wiring portion extending at a predetermined angle with respect to the width direction of the connector portion. When, characterized in that comprising a twist section connecting the this inclined wiring portion at both ends of the inclined wire portion the connector portion.

  According to the flexible printed wiring board of the present invention, the divided wiring portion twisted at, for example, a right angle with respect to the width direction of the connector portion is bent in a U shape along the moving surface of the electronic device, that is, the divided wiring portion. Therefore, it is possible to perform wiring by bending the width direction so that the width direction matches the thickness direction of the electronic device.

  According to the electronic device of the present invention, the flexible printed wiring board is expanded to the full width direction of the electronic device by bending the width direction of the divided wiring portion so as to match the thickness direction of the electronic device. Can be wired.

  As a result, even if the electronic device is made thinner, the flexible printed wiring board can be bent along the width direction that is considerably wider than the thickness of the electronic device. Can be reliably prevented. It becomes possible to maintain good conductivity of the flexible printed wiring board over a long period of time.

  Furthermore, the electronic device of the present invention using the flexible printed wiring board does not need to consider the minimum bending radius of the flexible printed wiring board when thinning, that is, the minimum bending radius of the flexible printed wiring board is the width direction of the electronic device. Therefore, it contributes to further thinning of electronic devices.

  Hereinafter, an embodiment of a flexible printed wiring board according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to such an embodiment. In addition, in the drawings used in the following description, in order to make the features of the present invention easier to understand, there is a case where a main part is shown in an enlarged manner for convenience, and the dimensional ratio of each component is the same as the actual one. Not necessarily.

  FIG. 1 is an external perspective view showing a flexible printed wiring board of the present invention used for wiring of, for example, a mobile phone (electronic device). FIG. 2 is a plan view of the flexible printed wiring board, and FIG. 3 is a cross-sectional view showing the layer structure of the flexible printed wiring board. 2 shows an enlarged width direction of the flexible printed wiring board, and FIG. 3 shows an enlarged thickness direction.

  The flexible printed wiring board 20 of the present invention includes, for example, a flexible substrate 21 made of an insulating flexible (flexible) resin film and the like, and a number of elongated conductive layers 22 formed on one surface of the flexible substrate 21. 22... The flexible substrate 21 may be formed in a thin strip shape (ribbon shape) having a predetermined width and length. In the present invention, the width direction W represents the short side direction of the strip-shaped flexible substrate 21 or the flexible printed wiring board 20, and the length direction L similarly represents the long side direction. To do.

  The conductive layers 22, 22... Are formed on one surface of the flexible substrate 21 so as to be elongated along the length direction L. The conductive layers 22, 22... Are formed in parallel along the width direction W at a predetermined interval from each other. The conductive layers 22, 22... Only need to be made of a metal having excellent conductivity, for example, a copper thin film, a silver thin film, an aluminum thin film, or the like.

  As shown in FIG. 3, insulating protective layers 23 and 24 are formed so as to sandwich the flexible substrate 21 having the conductive layer 22 formed on one surface in the thickness direction T1. Further, it is preferable to further form a magnetic shield layer 25 for electromagnetic shielding so as to overlap with the protective layer 23.

  As shown in FIGS. 1 and 2, the flexible printed wiring board 20 includes a flat wiring portion S2 and connector portions S1 formed at both ends of the flat wiring portion S2 in the length direction L thereof. Among these, the connector part S1 is a region (part) where the conductive layers 22, 22... Are exposed without forming the protective layer 23 and the magnetic shield layer 25. In this connector part S1, the protective layer 24 is overlaid. In addition, a reinforcing layer 26 is preferably formed (see FIG. 3).

  Such connector part S1 is used for the electrical connection between the 1st circuit of a mobile telephone (electronic device) and a 2nd circuit, for example. In the connector portion S1, it is preferable that gold plating or silver plating is further applied so as to cover the peripheral surfaces of the exposed conductive layers 22, 22.

  The flat wiring portion S2 is formed to be freely bent as a whole. And the slit (cut line) 27 extended in the length direction L is formed in two positions which divide the width direction W of the flexible printed wiring board 20 into 3 for example. The slit 27 is cut through the magnetic shield layer 25 to the protective layer 24 in the flat wiring portion S <b> 2 of the flexible printed wiring board 20.

  By such a slit 27, the flat wiring portion S2 is divided into a plurality of divided wiring portions S21, S22, S23 divided into a predetermined number of conductive layers 22, 22,. It is formed. The divided wiring portions S21, S22, S23 partitioned by the two slits 27 can swing within a certain range with respect to the adjacent divided wiring portions.

  Further, the flat wiring portion S2 has an inclined wiring portion D1 whose width direction w1 extends at a predetermined angle θ1 with respect to the width direction w2 of the connector portion S1, and the inclined wiring portion at both ends of the inclined wiring portion D1. It consists of the twist part D2 which connects D1 and connector part S1. An angle θ1 formed by the width direction w1 of the inclined wiring portion D1 and the width direction w2 of the connector portion S1 may be, for example, substantially a right angle (about 90 °).

  Further, each twisted portion D2 of the divided wiring portions S21, S22, S23 is flat until the width direction rotates about 90 ° between the connector portion S1 and the inclined wiring portion D1 (the width direction is changed from horizontal to vertical). This is a portion formed by twisting the wiring portion S2.

  In the flexible printed wiring board 10 having such a configuration, the width direction of the inclined wiring portion D1 of the flat wiring portion S2 forms an angle θ1, for example, a right angle with respect to the width direction w2 of the connector portion S1. Since the shape extends to L, for example, in a sliding mobile phone, the inclined wiring portion D1 is bent into a U shape along the moving surfaces of the two housings, that is, the width direction w1 of the inclined wiring portion D1. Can be bent and wired so as to match the thickness direction of the mobile phone. In addition, the effect | action at the time of using a flexible printed wiring board provided with such a division | segmentation wiring part and an inclination wiring part for an electronic device (cellular phone) is described later.

FIG. 4 is an external perspective view showing another embodiment of the flexible printed wiring board of the present invention used for wiring of an electronic device. FIG. 5 is a plan view of the flexible printed wiring board shown in FIG. In FIG. 5, the width direction of the flexible printed wiring board is enlarged and displayed.
The flexible printed wiring board 40 in this embodiment includes, in the length direction L, a flat wiring portion S4 and connector portions S3 formed at both ends of the flat wiring portion S4. In the connector portion S3, the conductive layer 42 is provided. , 42... Are exposed.

  In the flat wiring portion S4, slits (cut lines) 47 extending in the length direction L are formed at, for example, two positions that divide the width direction W of the flexible printed wiring board 40 into three parts. The flat wiring portion S4 of the plate 40 is formed with a plurality of divided wiring portions S41, S42, S43 divided into a predetermined number of conductive layers 42, 42... Among a plurality of conductive layers 42, 42.

  Further, the flat wiring portion S5 has an inclined wiring portion D3 whose width direction w3 extends at an angle θ2 with respect to the width direction w4 of the connector portion S3, and the inclined wiring portion at both ends of the inclined wiring portion D3. It consists of the twist part D4 which connects D3 and connector part S3. The angle θ2 formed by the width direction w3 of the inclined wiring portion D3 and the width direction w4 of the connector portion S3 may be substantially a right angle (about 90 °), for example.

  Further, each twisted portion D4 of the divided wiring portions S41, S42, and S43 is a flat wiring until the width direction is rotated by 90 ° between the connector portion S3 and the inclined wiring portion D3 (the width direction is changed from horizontal to vertical). This is a part formed by twisting the part S4.

  The flexible printed wiring board 40 is formed with a binding means 49 that bundles the divided wiring portions S41, S42, and S43 and stacks them along the thickness direction T2. By such a binding means 49, the divided wiring portions S41, S42, and S43 are integrated to form a binding wiring portion 48 having an extremely compact outer shape having a rectangular cross section. The bundling means 49 may be any means that collectively engages the divided wiring portions S41, S42, and S43 with, for example, an insulating hard resin member or a soft resin member such as rubber.

  Further, in the present embodiment, such binding means 49 is formed near both ends of the divided wiring portions S41, S42, and S43, but depending on the length of the divided wiring portions S41, S42, and S43, the divided wiring portion S41. , S42, and S43 need only be formed in an appropriate number so that they do not individually swing and separate.

Next, an embodiment of the electronic apparatus of the present invention provided with the flexible printed wiring board shown in FIGS. FIG. 6A is an external perspective view showing the state of the slide type mobile phone as an example of the electronic apparatus of the present invention when it is carried (standby), and FIG. It is an external appearance perspective view which shows the state of time.
The mobile phone (electronic device) 10 includes a first housing 11 and a second housing 12. The first casing 11 and the second casing 12 are arranged so as to overlap each other, and the second casing 12 slides within a predetermined range along the moving surface 11a of the first casing 11. It is engaged with the first casing 11 so as to be capable of sliding.

  For example, an operation button 13 is arranged on the first housing 11. In addition, for example, a liquid crystal display (LCD) 14 is disposed in the second housing 12. When the mobile phone 10 is carried (standby), the mobile phone 10 is slid to a position where the outer shapes of the first housing 11 and the second housing 12 match in order to reduce the outer shape and improve the portability. Then, the operation button 13 is concealed (see FIG. 6A). Further, during a call (during operation), the second casing 12 is slid relative to the first casing 11 until the operation button 13 is exposed (see FIG. 6B).

  FIG. 7 is an explanatory diagram showing a state of wiring by the flexible printed wiring board of the mobile phone shown in FIG. In the first circuit 63 formed in the first casing 11 of the slide type mobile phone 10 and the second circuit 64 formed in the second casing 12, each connector is formed at the position where the mobile phone is formed. It is formed at a position shifted in 10 width directions WB, that is, a position not aligned on a straight line.

  The flexible printed wiring board 40 for wiring between the first circuit 63 and the second circuit 64 is a bundled wiring in which the width direction is twisted, for example, at a right angle with respect to the width direction w4 of the connector portion S3. The portion 48 can be bent in a U-shape along the moving surface 10a of the mobile phone 10, that is, the wiring direction can be bent so that the width direction of the binding wiring portion 48 matches the thickness direction of the mobile phone. Become.

  As described above, the flexible printed wiring board 40 is bent so that the minimum bending radius r is expanded to the full width direction WB of the mobile phone 10 by bending the width direction of the binding wiring portion 48 so as to match the thickness direction of the mobile phone. can do.

  Since the flexible printed wiring board used for wiring of the conventional slide type mobile phone is bent in a U shape along the thickness direction of the mobile phone, the minimum bending radius has to be less than half of the thickness of the mobile phone. . However, by using the flexible printed wiring board 40 of the present invention, even if the mobile phone is made thinner, it can be bent along the width direction WB which is considerably wider than the thickness of the mobile phone. Breakage and disconnection of the conductive layers 42, 42... Due to repeated bending can be reliably prevented. It becomes possible to maintain good conductivity of the flexible printed wiring board 40 over a long period of time.

  Furthermore, in the electronic device (mobile phone) of the present invention using the flexible printed wiring board 40, it is not necessary to consider the minimum bending radius of the flexible printed wiring board 40 when thinning, that is, the flexible printed wiring board 40 of the present invention. Since the minimum bending radius depends on the width direction WB of the mobile phone 10, it contributes to further thinning of the mobile phone (electronic device) 10.

  In the above-described embodiment, the mobile phone is exemplified as the electronic device, but it is needless to say that the present invention can be applied to various information terminals, portable electronic devices, and the like. Further, the number of housings is not necessarily two, and the flexible printed wiring board of the present invention can be applied to the wiring of an electronic device composed of three or more housings. In addition to the slidable engagement as in the above-described embodiment, the engagement form of the plurality of housings may be an engagement form by rotation, bending, or a combination thereof.

  The flat wiring part of the flexible printed wiring board is not limited to one divided into three divided wiring parts by two slits as in the above-described embodiment, and two divided wirings by one slit. It may be divided into four or more divided wiring parts by forming three or more slits.

  Examples in which the effects of the present invention are verified will be described below. As an example of the present invention, as shown in FIGS. 4 and 5, a bundled wiring portion in which three divided wiring portions are formed by two slits provided in the flat wiring portion, and these three divided wiring portions are further bound by a binding means. The flexible printed wiring board which has this was made into the example of this invention. Further, as a comparative example, a conventional flexible printed wiring board extending with a uniform width without providing such a slit was used as a comparative example.

The specifications common to the examples of the present invention and the comparative examples are as follows.
1. Conductive layer formation pitch: 0.3 mm,
2. Number of parallel conductive layers: 12 (in the present invention, slits are formed for every four conductive layers, and three divided wiring portions having four conductive layers are formed)
3. Total length of wiring plate: 100mm
4). Connector length: 3mm
5). Reinforcing plate length of connector part: 5mm
6). Width of each conductive layer: 0.2mm
7). Thickness of each conductive layer: 0.018mm
8). 8. Flexible substrate: polyimide film (thickness 13 nm) + adhesive Protective layer: polyimide film (thickness 13 nm) + adhesive 10. Magnetic shield layer: silver paste + carbon coat (thickness 10nm)

Using the flexible printed wiring boards of the present invention example and the comparative example having the above-described configuration, the bending operation was repeatedly performed to verify the bending resistance.
The verification method was based on the IPC method, and the number of samples was examined for 10 samples with a stroke of 25 mm and a speed of 500 times / minute. These verification results (average values) are shown in Table 1.

  According to the results shown in Table 1, the flexible printed wiring board of the example of the present invention has a bending resistance of about 7 times with a bent wiring space of 3 mm as compared with the flexible printed wiring board of the conventional comparative example. found. The remarkable bending-resistant effect of the flexible printed wiring board of this invention was confirmed.

It is a perspective view which shows an example of the flexible printed wiring board of this invention. It is a top view which shows an example of the flexible printed wiring board of this invention. It is sectional drawing which shows an example of the flexible printed wiring board of this invention. It is a perspective view which shows another example of the flexible printed wiring board of this invention. It is a top view which shows another example of the flexible printed wiring board of this invention. It is a perspective view which shows an example of the electronic device (cellular phone) of this invention. . It is explanatory drawing which shows the wiring state of the electronic device (cellular phone) of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Electronic device (mobile phone), 11, 12 Case, 20 Flexible printed wiring board, 22 Conductive layer, 27 Slit, 48 Bundling wiring part, 49 Bundling means, S1 Flat wiring part, S2 Connector part, S21, S22, S23 Divided wiring part, D1 inclined wiring part, D2 twisted part.

Claims (7)

A plurality of housings having circuits are engaged so as to be relatively movable, and the circuits of these housings are electrically connected by a flexible printed wiring board,
The flexible printed wiring board includes a strip-like flexible substrate having a predetermined width and length, and is elongated along the length direction of the flexible substrate, and is spaced apart from each other along the width direction. A flat wiring portion having at least a plurality of conductive layers arranged in parallel, and a flat connector portion formed at each end of the flat wiring portion and electrically connected to the circuit,
The flat wiring portion is divided from a plurality of divided wiring portions divided into a predetermined number of conductive layers among the multiple conductive layers by slits formed in the flexible substrate along a length direction of the flexible substrate. Become
The divided wiring portion has an inclined wiring portion whose width direction extends at a predetermined angle with respect to the width direction of the connector portion, and connects the inclined wiring portion and the connector portion at both ends of the inclined wiring portion. An electronic device comprising a twisted portion.   The electronic device according to claim 1, wherein the inclined wiring portion has a width direction substantially perpendicular to a width direction of the connector portion.   The electronic apparatus according to claim 1, further comprising a binding unit that bundles the plurality of inclined wiring portions and stacks the inclined wiring portions in the thickness direction.   The electronic device according to claim 1, wherein the inclined wiring portion is arranged to be bent along a moving surface of the housing.   The electronic device according to claim 4, wherein the inclined wiring portion is arranged to be bent along a moving surface of the housing so as to form a U shape.   The plurality of casings include a first casing and a second casing that is slidably attached to the first casing. The electronic device as described in the paragraph. A strip-like flexible substrate having a predetermined width and length, and a plurality of conductive wires extending in the longitudinal direction of the flexible substrate and arranged in parallel at predetermined intervals along the width direction. A flexible printed wiring board comprising at least a flat wiring part provided with a layer, and flat connector parts respectively formed at both ends of the flat wiring part,
The flat wiring portion is divided from a plurality of divided wiring portions divided into a predetermined number of conductive layers among the multiple conductive layers by slits formed in the flexible substrate along a length direction of the flexible substrate. Become
The divided wiring portion has an inclined wiring portion whose width direction extends at a predetermined angle with respect to the width direction of the connector portion, and connects the inclined wiring portion and the connector portion at both ends of the inclined wiring portion. A flexible printed wiring board comprising a twisted portion.

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