JP4539859B2 - Flexible circuit board and electronic device using the flexible circuit board - Google Patents

Description

  The present invention relates to a flexible circuit board for connecting circuits in two casings in an electronic apparatus in which two casings are rotatably connected by a hinge portion, and an electronic apparatus using the flexible circuit board.

  For example, in a foldable electronic device typified by a cellular phone or a portable information terminal having a foldable structure, as shown in FIG. It has a structured.

  In this electronic apparatus, a substantially crank-shaped flexible circuit board 203 as shown in FIG. 13A is used for electrical connection between the circuits 201 and 202 provided in the first and second casings, respectively. Has been.

  In this case, as shown in FIGS. 13B and 13C, the flexible circuit board 203 has a central portion wound in a loop in the hinge portion 103, and both ends thereof are first and first, respectively. 2 are connected to the circuits 201 and 202 in the two casings 101 and 102.

As a result, the flexible circuit board 203 can be bent at the loop position of the hinge part 103 as the electronic device rotates, and the tension and slack applied to the flexible circuit board 203 can be absorbed into the hinge part 103. (For example, see Patent Document 1 and Patent Document 2)
Japanese Patent No. 2821333 JP 2005-142425 A

  However, in the electronic device having the above-described conventional structure (see FIG. 12), the flexible circuit board 203 is wound once in a loop shape within the hinge portion 103, so that the assembly process of the electronic device is complicated.

  Further, according to the structure of the conventional electronic device (see FIG. 12), the bending operation of the flexible circuit board 203 accompanying the opening and closing of the electronic device is such that the central portion of the flexible circuit board is in a state where the electronic device is opened 180 degrees. The hinge 103 is wound once in a loop (see FIG. 14C), and as the electronic device is closed, the central portion of the flexible circuit board 203 is further bent (see FIG. 14B). ) When the electronic device is completely closed, the central portion of the flexible circuit board 203 is wound once and a half in a loop shape (see FIG. 14A). For this reason, stress is generated in the flexible circuit board 203 when the electronic device is opened 180 degrees, and the stress is complicated.

  In addition, the stress increased as the electronic device was closed, and the stress became complicated.

  Further, since the loop portion 301 of the flexible circuit board must be accommodated within the inner diameter of the hinge portion 103, the loop portion 301 of the flexible circuit board 203 is used in a small electronic device such as a foldable mobile phone. Therefore, the bending radius must be small, and a larger stress is generated.

  As described above, in the electronic device having the conventional structure shown in FIG. 12, the flexible circuit board 203 is repeatedly bent and stretched due to repeated rotations of the electronic equipment, and a large stress is generated several times. There was a problem that the wiring pattern was damaged and was easily disconnected.

  Conventionally, for example, as shown in FIGS. 15 to 17, in the bent portion of the flexible circuit board, the wiring pattern is formed only on one surface of the circuit board, so that the damage of the wiring pattern due to the stress as described above can be reduced. We tried to prevent disconnection as much as possible.

  That is, in the example shown in FIG. 15, a wiring pattern is formed on a flexible base material in which a conductor layer 112 is laminated on one side of a base film 113, and a coverlay film 111 coated with an adhesive is laminated thereon to form a wiring pattern. It is a single-sided flexible circuit board with a protected structure.

  Further, in the example shown in FIG. 16, a circuit in which a wiring pattern in a region to be a bent portion is formed on a double-sided flexible base material in which a conductor layer 112 is laminated on both surfaces of a base film 113 is formed on each wiring pattern. This is a double-sided flexible circuit board having a structure in which a wiring pattern is protected by laminating a cover lay film 111 coated with an adhesive.

  Further, in the example shown in FIG. 17, a circuit in which a wiring pattern of a region to be a bent portion is formed on a double-sided flexible base material in which a conductor layer 112 is laminated on both sides of a base film 113 is formed on each wiring pattern. A four-layer flexible circuit board having a structure in which a solder resist 115 is formed after a cover lay film 111 coated with an adhesive is laminated and a circuit is formed by further laminating a prepreg 114 and a conductor layer 112 on both sides. .

  As described above, the bending portion of the wiring is formed in one layer to improve the bending performance of the flexible circuit board.

  However, since all of these means for improving the bending performance are wired only on one side of the flexible circuit board, the circuit wiring becomes fine and the economic efficiency is poor. In addition, since wiring is performed only on one side, the number of circuit wirings is limited, and in recent years when the function of a device is being improved, a sufficient number of wirings cannot be satisfied. Further, in the above two examples using the double-sided flexible circuit board, there is a problem that it is necessary to remove the constituent material of the bent portion (loop portion 301) and the economic efficiency is poor.

  Therefore, the present invention has been made in order to solve the above-described problems, and an object of the present invention is to connect the first and second housings so as to be rotatable by a hinge portion, and the inside of the first and second housings. In an electronic device in which the circuits are electrically connected by a flexible circuit board, a flexible circuit board that can significantly reduce the stress generated when the casings rotate to each other and a highly durable circuit using the same To provide electronic equipment.

In order to solve the above-mentioned problems, a flexible circuit board according to the present invention is a flexible circuit board that connects circuits in first and second casings that are rotatably connected by a hinge part , into the hinge part . is inserted, extends along the rotation axis of the hinge portion, and four or more parallel portions parallel three or more orthogonal portion that is orthogonal to the rotary shaft and the rotary shaft, the first and second when the housing is rotated, the bent piece is bent in the orthogonal part, is connected to one end of the bent piece, it is connected to extend into the first housing to the first housing of the circuit A first connection piece and a second connection piece connected to the other end of the bent piece, extending into the second housing and connected to a circuit in the second housing , A flat state when the angle between the first housing and the second housing is 90 degrees Said being connected to the first enclosure of the circuit and the second housing of the circuit so that said.

  In the flexible circuit board having such a feature, a plurality of portions that intersect the rotation axis of the hinge portion in the bent piece are independently bent as the first and second casings are rotated. As a result, the flexible circuit board is bent at the bent portions (locations intersecting the rotation axis of the hinge portion) simultaneously, and as a result, the first and second casings are rotated. The generated stress can be reduced.

Further, according the flexible circuit board according to the present invention, constitutes at least one side of the bent piece so as to protrude outwardly of the hinge Then, be further reduced stress generated in the flexible circuit board at the time of bending it can.

  When the flexible circuit board is bent, the other portion of the hinge portion intersecting the rotation axis is rotated about the one end and bent between the two ends. The width of the bent piece is set such that at least one side portion of the bent piece protrudes outside the hinge portion so that the distance between both ends becomes longer, so that the rotation angle at the time of the rotational movement is small. Become. Therefore, the bending radius increases and the generated stress can be reduced.

  The flexible circuit board according to the present invention is characterized in that at least the bent piece is reinforced by an elastic member.

  Further, the first and second connecting pieces and the bent piece are reinforced by an elastic member.

  Thus, by reinforcing the elasticity of the flexible circuit board, it is possible to prevent the elastic deformation at the time of bending from becoming irregular.

  At this time, if a thin material is used for the elastic member, it is possible to reduce the influence on the bendability due to the difference between the inner and outer circumferences that occurs during bending.

  Furthermore, according to the flexible circuit board of the present invention, if at least one end of the elastic member is a free end, the influence on the bendability due to the circumferential difference between the inner side and the outer side that occurs during bending can be reduced.

  In addition, according to the flexible circuit board of the present invention, when a conductive material is used for the elastic member and the elastic member is grounded to the flexible circuit board, a shield can be formed.

  According to the present invention, unlike the conventional one, since the flexible circuit board is not wound in a loop shape within the hinge portion, the assembly process of the electronic device is simplified, and the electronic device can be produced economically. .

  Moreover, since the flexible circuit board according to the present invention bends independently at a plurality of locations, the generated stress is dispersed. Furthermore, the bending radius of those bendings is large, and the generated stress is smaller than that of the conventional flexible circuit board. Therefore, durability against bending is high.

  Furthermore, according to the electronic device and the flexible circuit board according to the present invention, as described above, since the generated stress is small, even if the wiring pattern is formed on both sides of the substrate, the wiring pattern is hardly damaged or disconnected, and the electronic device It is possible to maintain durability against bending, and it is possible to secure a sufficient number of wirings without making the wiring pattern fine, which is excellent in economic efficiency and productivity.

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

  FIG. 1 is a main part schematic cross-sectional view showing an embodiment of an electronic apparatus according to the present invention, and FIG. 2 is a main part schematic cross-sectional view showing another embodiment.

  As shown in FIGS. 1 and 2, in the electronic device, the first housing 11 and the second housing 12 are rotatably connected by the hinge portion 13, and are further incorporated in the first housing 11. The first circuit board 21 and the second circuit board 22 built in the second housing 12 are connected by a flexible circuit board 23. Further, connector connecting portions 24 and 25 are respectively attached to both ends of the flexible circuit board 23, and the connector connecting sections 24 and 25 are connected to the first circuit board 21 and the second circuit board 22, respectively. .

  Hereinafter, each part is explained in full detail.

  3A is a front view showing the flexible circuit board 23 in a state before being incorporated in an electronic device, and FIG. 3B is a front view showing the flexible circuit board 23 in a state in which it is incorporated in an electronic device. (C) is a side view which shows the flexible circuit board 23 of the state integrated in the electronic device.

  As shown in FIG. 3A, the flexible circuit board 23 is inserted into the hinge portion 13 and extends in a zigzag shape along the rotation axis 70 of the hinge portion 13 and one end of the bent piece. A first connection piece 51 that is connected to the first casing 11 and connected to a circuit in the first casing 11, and is connected to the other end of the bent piece 53. 12 and a second connection piece 52 that extends into the circuit 12 and is connected to a circuit in the second housing.

  The zigzag shape may be a shape that is folded twice or more in a crank shape as shown in FIG. 3A, or a shape that is folded twice or more in a lightning bolt shape as shown in FIG.

  As shown in FIGS. 3A and 3B, the shape of the bent piece 53 of the flexible circuit board 23 is a zigzag shape that is folded twice in a crank shape along the rotation axis of the hinge portion. It has three orthogonal portions 41, 42, 43 orthogonal to the shaft 70, and four parallel portions 31, 32, 33, 34 parallel to the rotating shaft 70 including the two folded portions 31, 32. The flexible circuit board 23 is bent at each of the orthogonal portions 41, 42, 43 when the first and second casings 11, 12 rotate.

  The bent piece 53 of the flexible circuit board in this embodiment has a zigzag shape (see FIG. 3A) that is folded back twice into a crank shape so as to be orthogonal to the rotation shaft 70. Even if it is not orthogonal, if it intersects the rotation axis 70 and bends when the first and second casings 11 and 12 are rotated, it is not orthogonal to the rotation axis 70 as shown in FIG. Also good. Further, the number of times of folding may be two or more.

  In the above-described embodiment, the width of the bent piece 53 is slightly shorter than the inner diameter of the hinge portion 13 (see FIGS. 2 and 3), but not limited to this, at least one side portion of the bent piece 53 is a hinge. The dimension may be set so as to protrude to the outside of the portion 13 (see FIGS. 1 and 6A).

  According to the flexible circuit board 23 according to this embodiment, when the first casing 11 is half opened with respect to the second casing 12, the flexible circuit board 23 is in a flat state without bending. When the flexible circuit board 23 is attached to the device (see FIG. 1), bending of the flexible circuit board 23 accompanying the rotation of the casings 11 and 12 can be suppressed to a small value.

  Therefore, in an electronic device that can be opened up to 180 degrees, the flexible circuit board 23 is in a flat state with the first casing 11 opened 90 degrees with respect to the second casing 12. When the flexible circuit board 23 is attached (see FIG. 3C), bending of the flexible circuit board 23 accompanying the rotation of the electronic device can be suppressed to a low level.

  Here, the bending operation of the flexible circuit board 23 will be described with reference to FIG.

  When the first housing 11 is opened 90 degrees with respect to the second housing 12, the flexible circuit board 23 does not bend (see FIG. 5B), and is a form before being incorporated into an electronic device (see FIG. 5). 3 (A)) is maintained.

Next, the first housing 11 is further opened 90 degrees with respect to the second housing and is fully opened, that is, the angle between the first housing 11 and the second housing is 180 degrees. At this time, the flexible circuit board 23 bends at the three orthogonal portions 41, 42, and 43 in the bent piece 53 (see FIG. 5C). That is, in this state, the two orthogonal portions 41 and 42 orthogonal to one of the zigzag folded portions 31 bend in a symmetric direction with respect to the folded portion 31, and similarly, the other zigzag folded portion. The two orthogonal portions 42 and 43 orthogonal to 32 are bent in a symmetric direction with respect to the other folded portion 32.

In contrast to the above, when the first casing 11 and the second casing 12 are completely closed, the flexible circuit board 23 has three orthogonal portions 41, 42, 43 of the bent piece 53. Thus, it bends in the opposite direction to that when it is opened 180 degrees (see FIG. 5A). That is, in this state, the two orthogonal portions 41, 42 perpendicular to one of the folded portion 31 is bent symmetrically direction with respect to the folded portion 31, likewise, the two orthogonal to the other folded portion 32 perpendicular The portions 42 and 43 are bent in a symmetric direction with respect to the other folded portion 32.

  As described above, when the first casing 11 is opened 90 degrees with respect to the second casing 12, the flexible circuit board 23 is not bent, and the first casing 11 and the second casing 12 are not bent. When the flexible circuit board 23 is completely closed (see FIG. 5A) and when both the casings 11 and 12 are fully opened (the angle between the casings 11 and 12 is 180 degrees). The bent shape (see FIG. 5C) of the flexible circuit board 23 is symmetrical to each other.

  Here, when the flexible circuit board 23 is attached to an electronic device so that the flexible circuit board 23 is bent at the same left and right angles starting from a state where the flexible circuit board 23 is flat and not bent (see FIG. 3C), the flexible circuit board 23 is attached. Therefore, the stress generated in the flexible circuit board 23 can be kept small.

  Further, when the width of the bent piece 53 is set so that at least one side of the bent piece protrudes outside the hinge portion 13 (see FIGS. 1 and 6), both sides of the bent piece 53 are hinged. Compared with a flexible circuit board (see FIGS. 2 and 7) sized to fit inside the portion 13, the length of the orthogonal portions 41, 42, 43 is long, and the bending radius in the bending operation described above is long. As a result, the stress generated in the flexible circuit board 23 is reduced.

  As shown in FIGS. 1 and 6, connector connecting portions 24 and 25 are attached to both ends of the flexible circuit board 23, and the first casing 11 and the second housing are connected to each other via the connector connecting portions 24 and 25. The flexible circuit board 23 is connected to the circuit boards 21 and 22 in the casing 12.

  Further, as shown in FIG. 8, even if the first and second connection pieces 51 and 52 and the bent piece 53 of the flexible circuit board 23 are reinforced by elastic members 26 and 27 from both sides of the flexible circuit board. Good.

  In this way, by reinforcing the elasticity of the flexible circuit board 23, the elastic deformation at the time of bending can be accurately repeated.

  In order to reduce the influence on the bendability due to the difference between the inner and outer circumferences that occurs during bending, it is preferable to use a thin material of 200 μm or less for the elastic members 26 and 27.

  Further, only one end of each of the elastic members 26 and 27 may be attached to the flexible circuit board 23 by screw fixing 28 (see FIG. 8) so that at least one end of the elastic members 26 and 27 becomes a free end.

  As a result, the influence on the flexibility due to the difference between the inner and outer circumferences generated during bending can be absorbed by the screw-fixed portion 28.

  Further, when a conductive material such as a metal material is used for the elastic members 26 and 27 and the elastic members 26 and 27 are grounded to the flexible circuit board 23, a shield can be formed.

  In the electronic device as described above, since the stress generated at the time of bending is small, wiring patterns are formed on both sides of the double-sided flexible circuit board 23 in which the conductor layers are laminated on both sides of the film base (see FIGS. 9 to 11). Even in this case, sufficient bending resistance can be ensured.

  9 shows a double-sided flexible base material 60 in which a conductor layer 62 made of a 12 μm-thick copper foil is laminated on both sides of a 12.5 μm-thick film base 63 made of polyimide. A double-sided flexible circuit board having a structure in which a wiring pattern is formed on a base material 60 and a cover lay film 61 coated with an adhesive is laminated on each wiring pattern. A wiring pattern is secured.

  In the example shown in FIG. 9, a two-layer double-sided flexible circuit board is used, but a wiring pattern may be applied to the inner two layers of the four-layer flexible circuit board. That is, the one shown in FIG. 10 is obtained by obtaining a double-sided flexible base material 60 in which a conductor layer 62 made of 12 μm thick copper foil is laminated on both sides of a film base 63 made of polyimide having a thickness of 12.5 μm. A four-layer flexible structure having a structure in which a conductor layer 62 made of copper foil having a thickness of 12 μm is laminated on both surfaces of a flexible substrate 60 via a prepreg 64 having a thickness of 25 μm, and a solder resist 65 is further formed. The circuit board 23 is used, and the double-sided flexible circuit board 23 is wired in the inner two layers without removing the constituent material of the part orthogonal to the rotating shaft 70.

  Further, what is shown in FIG. 11 is to obtain a double-sided flexible base material 60 in which a conductor layer 62 made of 12 μm thick copper foil is laminated on both sides of a film base 63 made of polyimide having a thickness of 12.5 μm. A circuit is formed by laminating a conductive layer 62 made of copper foil having a thickness of 18 μm on both surfaces of the substrate 60 via a build-up resin 66 having a thickness of 30 μm, and a solder resist 65 is further formed to form a build-up layer. A four-layer flexible circuit board 23 provided with a wire is used, and wiring is made on the inner two layers without removing the constituent material of the double-sided flexible circuit board 23 perpendicular to the rotating shaft 70.

It is a principal part schematic sectional drawing which shows the side view which shows one Embodiment of the electronic device which concerns on this invention. It is a principal part schematic sectional drawing which shows other embodiment of the electronic device which concerns on this invention. 1 shows an embodiment of a flexible circuit board according to the present invention, FIG. 3A is a front view showing the flexible circuit board in a state before being incorporated in an electronic device, and FIG. 3B is incorporated in the electronic device. FIG. 3C is a side view showing the flexible circuit board in a state incorporated in an electronic device. It is a front view which shows other embodiment of the flexible circuit board based on this invention. FIG. 5A shows a bent shape of a flexible circuit board according to the present invention, and FIG. 5A is a side view showing the bent shape of the flexible circuit board when the first casing and the second casing are completely closed. FIG. 5B is a side view showing the shape of the flexible circuit board when the first housing is opened 90 degrees with respect to the second housing, and FIG. It is a side view which shows the bending shape of a flexible circuit board when it opens 180 degree | times with respect to 2 housing | casing. Another embodiment of the flexible circuit board based on this invention is shown, FIG. 6 (A) is a front view, FIG.6 (B) is a side view. FIG. 7A is a front view and FIG. 7B is a side view of still another embodiment of the flexible circuit board according to the present invention. FIG. 8A is an exploded perspective view and FIG. 8B is a perspective view showing still another embodiment of the flexible circuit board according to the present invention. It is a schematic sectional drawing which shows the specific example of the flexible circuit board based on this invention. It is a schematic sectional drawing which shows the other specific example of the flexible circuit board based on this invention. It is a schematic sectional drawing which shows the other specific example of the flexible circuit board based on this invention. It is a principal part schematic sectional drawing which shows the structure in the hinge part of the conventional electronic device. FIG. 13A shows a shape of a conventional flexible circuit board, FIG. 13A is a front view showing the shape of the flexible circuit board before being attached to an electronic device, and FIG. 13B is a flexible circuit board when attached to the electronic device. FIG. 13C is a side view showing the shape of the flexible circuit board when attached to the electronic device. FIG. 14A is a side view showing a bent shape of a flexible circuit board when the first casing and the second casing are completely closed; 14B is a side view showing a bent shape of the flexible circuit board when the first housing is opened 90 degrees with respect to the second housing, and FIG. 14C is the first housing. It is a side view which shows the bending shape of a flexible circuit board when this is opened 180 degree | times with respect to the 2nd housing | casing. It is a schematic sectional drawing which shows the layer structure of the conventional flexible circuit board. It is a schematic sectional drawing which shows the laminated constitution of the other conventional flexible circuit board. It is a schematic sectional drawing which shows the laminated constitution of the other conventional flexible circuit board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 1st housing | casing 12 2nd housing | casing 13 Hinge part 21 1st circuit board 22 2nd circuit board 23 Flexible circuit board 24, 25 Connector connection part 26, 27 Elasticity member 28 Screw fixing 31, 32 Folding part (Parallel part)
33, 34 Parallel portion 41, 42, 43 Orthogonal portion 51 First connection piece 52 Second connection piece 53 Bending piece 60 Double-sided flexible base material 61 Coverlay film 62 Conductor layer 63 Base film 64 Prepreg 65 Solder resist 66 Build-up Resin 70 Rotating shaft

Claims (8)

A flexible circuit board for connecting circuits in the first and second casings rotatably connected by a hinge part,
Wherein is inserted into the hinge portion, said extending along the rotation axis of the hinge portion, and four or more parallel portions parallel to the said rotary shaft and three or more orthogonal portion that is orthogonal to the rotation axis, the first A bent piece bent at the orthogonal portion when the first and second casings are rotated ;
A first connecting piece connected to one end of the bent piece, extending into the first casing and connected to a circuit in the first casing;
A second connecting piece connected to the other end of the bent piece, extending into the second casing and connected to a circuit in the second casing ;
The first casing and the second casing are connected to the circuit in the first casing and the circuit in the second casing so as to be in a flat state when the angle between the first casing and the second casing is 90 degrees. A flexible circuit board. The flexible circuit board according to claim 1, wherein at least one side of the bent piece is formed to protrude to the outside of the hinge portion.   The flexible circuit board according to claim 1, wherein at least the bent piece is reinforced by an elastic member.   3. The flexible circuit board according to claim 1, wherein the first and second connection pieces and the bent piece are reinforced by an elastic member.   The flexible circuit board according to claim 4, wherein at least one end of the elastic member is a free end.   The flexible circuit board according to claim 3, wherein the elastic member is a conductor.   The flexible circuit board according to claim 6, wherein the elastic member is grounded.   An electronic device comprising first and second housings rotatably connected by a hinge portion, wherein circuits in each housing are connected by the flexible circuit board according to any one of claims 1 to 7.

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