JP2008270621A - Flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible printed wiring board (FPC) for which the formation of a shield layer is facilitated by utilizing two wiring layers. <P>SOLUTION: By providing the shield layer by a magnification pattern 17 on one wiring layer (2) and arraying and forming two or more columns of a plurality of slits 6 linearly in the bend range of the magnification pattern 17, the flexibility of the FPC in the bend range is improved while keeping a shielding effect. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flexible printed wiring board, and more particularly to a flexible printed wiring board provided with a shield layer.

  It is known that the shielding performance of electromagnetic waves is enhanced by providing a shielding layer on a flexible printed circuit board (Flexible Printed Circuit (hereinafter also referred to as FPC)) used in electronic equipment. For example, in the case of an LCD module composed of an LCD panel, an FPC, and an LCD drive circuit component, an LCD drive circuit component for driving the LCD panel may be mounted on the FPC. Although noise is generated, a shield layer made of a metallic material is provided on the FPC in order to prevent the influence of this noise on other devices (for example, cellular phones).

  In addition, a configuration example in which a hole or the like is provided in a shield layer or the like in order to improve the flexibility of a flexible printed wiring board is also known (Patent Documents 1 and 2).

FIG. 9 is a diagram showing a configuration example of a conventional flexible printed wiring board. FIG. 9A shows a flexible printed wiring board described in Patent Document 1, in which a metal wire is attached to an FPC main body 110 in which a circuit layer 123 is bonded between base films 121 and 131 via adhesive layers 122 and 132. A shield layer 200 made of a knitted fabric made of braided metal, a mesh-like porous metal foil 210 by pressing metal foil, an adhesive layer 240, etc. is provided to give flexibility. FIG. 9B shows a flexible printed wiring board described in Patent Document 2, in which a ground layer 110D and a coverlay layer 110C are provided on the lower surface side of the base film 110A on which the wiring pattern P is provided. The coverlay layer 110B, the shield layer 110E, and the topcoat layer 110F are provided on the side, and the coverlay layers 110B and 110C, the shield layer 110E, and the topcoat layer 110F are arranged in a row along the fold line at the folding position 110Z in the direction perpendicular to the paper surface. The hole 110H is formed, and the bending rigidity at the bending position 110Z is made lower than the bending rigidity other than the bending position 110Z.
Japanese Patent Laying-Open No. 2005-251958 (see FIGS. 1 and 2) JP 2006-294929 A (see FIGS. 8 and 9)

  As described above, when a shield layer made of a metallic material is provided on a flexible printed circuit board (FPC), there is a problem that the flexibility (flexibility) of the FPC is lowered by the provided shield layer. There is also known an FPC in which the entire shield layer of the substrate is made of a knitted fabric of a metal wire or a mesh-like porous metal foil, or a plurality of rows of holes are formed in a portion of the shield layer along the crease.

  However, any conventional FPC has a structure in which an independent shield layer is provided on the FPC main body, which not only makes the structure complicated, but also requires a new process for forming the shield layer. Therefore, the number of processes increases, which is disadvantageous in manufacturing. In particular, in the former (Patent Document 1), a knitted fabric of a metal wire or a mesh-like porous metal foil is prepared and provided on the entire surface of the FPC. Will also increase. In the latter (Patent Document 2), a plurality of holes are arranged in a row along the crease in the shield layer of the FPC. In addition to an increase in cost due to an increase in the number of steps for forming the shield layer, a row of holes is arranged. Thus, it is difficult to improve the flexibility sufficiently.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and to provide an FPC having improved flexibility while facilitating formation of a shield layer by using two wiring layers and maintaining a shield effect. It is in.

  The flexible printed wiring board of the present invention uses the upper layer side and the lower layer side of the base film as a wiring layer, forms an enlarged pattern on either the upper layer side or the lower layer side as a shield layer, A plurality of slits in the crease direction are arranged in the folding range, the plurality of slits are arranged in a plurality of rows, and an overcode layer is provided on the outer side of the wiring layer, and the slits are arranged in the folding range of the overcode layer. It is characterized in that the same-shaped slits overlapped with each other are arranged.

  In addition, a wiring pattern is formed in an outer region in the same layer as the enlarged pattern, and a slit is arranged in a fold direction in a folding range of an overcoat layer on the wiring pattern, and the shield layer includes a wiring layer It was formed by the same process.

  According to the present invention, by forming an enlarged pattern on one of the two wiring layers on the upper layer side and the lower layer side of the base film to form a shield layer, there is no need to form a dedicated shield layer independent of the wiring layer. At the same time, by arranging a plurality of slits in the folding range of the enlarged pattern, it is possible to improve the flexibility of the FPC in the desired folding range while maintaining the shielding effect.

  In particular, since the plurality of slits are arranged in a plurality of rows and the plurality of slits are arranged in the outer overcoat layer of the enlarged pattern, the flexibility can be sufficiently improved.

  In addition, since the wiring pattern is formed in the outer area of the enlarged pattern and the slits are arranged in the folding direction in the overcoating layer on the upper layer of the wiring pattern, the overall flexibility of the FPC folding range can be ensured. Is possible.

  Furthermore, a manufacturing method that uses a manufacturing method for forming a wiring pattern on a base film of an FPC and simultaneously forms a shield layer having slits in the same layer in the same process for manufacturing a wiring layer is applicable. Therefore, it is possible to avoid an increase in the cost of forming the shield layer.

(Embodiment 1)
(Description of configuration)
The first embodiment of the flexible printed wiring board of the present invention will be described below in detail with reference to a configuration example of the flexible printed wiring board of the LCD module.

  FIG. 1 is a side view of the configuration of the LCD module and the folded state of the FPC of the present embodiment, and FIG. 2 is a front view of the FPC of FIG. 1 in an unfolded state.

  As shown in FIG. 1, the LCD module 4 includes an LCD panel 1, an FPC 2 having one end connected to the end of the LCD panel 1, and an LCD drive circuit component 3 mounted on the FPC 2.

  In addition, the FPC 2 of the present embodiment includes a shield layer, and is configured by arranging bending slits (slits) 6 in a plurality of rows in the shielding layer in the bending range 5 of the FPC 2 as shown in FIG.

  3 is a view showing a cross section of the BB portion of the FPC 2 in FIG. 2, and FIG. 4 is a view showing a cross section of the AA portion of the FPC 2 in FIG.

  The configuration other than the slit 6 of the FPC 2 of the present embodiment is formed in the base film 7 which is the base material of the FPC 2 and the lower layer of the base film 7, as shown in FIG. 3 (cross section BB in FIG. 2). The first wiring layer 8 that electrically connects the LCD panel 1 and the LCD drive circuit component 3 and the control circuit of the device (for example, a mobile phone), and an overcoat layer (lower layer) for insulating the wiring layer 8 ) 9 and further on the upper layer of the base film 7 to insulate the shield layer 10 from the shield layer 10 formed on the second wiring layer for suppressing noise generated from the LCD drive circuit component 3 and the wiring layer 8. And an overcoat layer (upper) 11.

  Further, the configuration of the slit 6 of the FPC 2 is a configuration in which a plurality of slits 6 penetrating vertically through the shield layer 10 and the overcoat layer (upper) 11 are provided as shown in FIG. 4 (cross section AA in FIG. 2). The area in each slit 6 includes a base film 7 serving as a base material for the FPC 2, and the LCD panel 1, the LCD drive circuit component 3 and a device (for example, a mobile phone) formed below the base film 7. The wiring layer 8 electrically connects between the control circuits, and an overcoat layer (lower) 9 for insulating the wiring layer 8.

  That is, as shown in FIG. 3 (cross section BB in FIG. 2), the portion of the bending range 5 without the slit 6 is the base film 7 serving as the base material of the FPC 2 and the wiring layer formed below the base film 7. 8, an overcoat layer (lower) 9 that insulates the wiring layer 8, a shield layer 10 that shields noise on the upper layer of the base film 7, and an overcoat layer (upper) 11 that insulates the shield layer 10. Since the shield layer 10 and the overcoat layer 11 are not formed at the location where the slit 6 is provided, the flexibility is excellent. The shape, the number, and the arrangement relationship of the slits 6 are determined in consideration of the bending at the time of mounting the FPC and after the mounting so that the slit 6 is bent from a certain straight line when being bent in the bending range 5.

  As is clear from the above configuration, the FPC 2 of the present embodiment basically has a configuration composed of two wiring layers forming the first and second wiring layers on both the upper and lower layers of the base film 7. In the embodiment shown in FIGS. 3 and 4, the shield layer 10 is formed on the upper wiring layer of the base film 7 as an enlarged pattern in a range covering a predetermined region of the lower wiring layer.

  As a method for forming the shield layer 10 according to the present embodiment, the slit 6 in the region covering the predetermined region of the lower wiring layer is formed on the upper wiring layer of the base film 7 together with the wiring pattern of the FPC wiring layer. It can be formed as an enlarged pattern from the wiring layer provided.

  By adopting such a pattern shape and structure of the shield layer of the FPC, it is possible to manufacture the upper wiring layer of the base film 7 and the enlarged pattern having the slits 6 in a single process. Further, it is preferable that the enlarged pattern is enlarged from the ground pattern of the wiring layer to form a shield.

(Description of operation)
Next, functions and operations of the FPC according to the present embodiment will be described using the example of the LCD device shown in FIGS.

  1 to 4, the LCD module 4 includes an LCD panel 1, an FPC 2, and an LCD drive circuit component 3. One end of the FPC 2 is electrically connected to the LCD panel 1 by a connector or the like, and the other end of the FPC 2. The LCD drive circuit component 3 is mounted on the upper layer portion of the shield layer having an enlarged pattern on the side, and a control circuit such as a mobile phone is connected to the other end side.

  Therefore, noise generated from the LCD drive circuit component 3 on the upper layer of the base film 7 and the wiring layer 8 on the lower layer, and noise generated from electronic components disposed on the upper side and the lower side of the FPC 2, Since the shield layer 10 is electromagnetically shielded by the upper shield layer 10, the mutual influence is eliminated, and the shield layer 10 has a plurality of elongate slits in the folding range in a direction perpendicular to the folding direction in order to maintain the shielding effect. Since a plurality of rows are formed, a decrease in flexibility (flexibility) caused by the formation of the metallic enlarged pattern of the shield layer 10 is partially enhanced only within the range, and bending at the location is free. It is possible to realize a suitable bent shape.

  In particular, in the bending range 5, the longitudinal (long side) directions of the plurality of slits 6 penetrating the shield layer 10 and the overcoat layer 11 are arranged in a straight line, and a plurality of rows are formed, so that Therefore, when folded in the folding range 5, the slit 6 can be easily folded from a plurality of straight lines, and the flexibility of the FPC is sufficiently improved while maintaining the shielding effect.

  As described above, the configuration in which the shield layer of the FPC is formed between the wiring layer and the mounted circuit component by the example of the LCD module has been shown. However, when the shield layer is arranged upside down with respect to the above embodiment with respect to the base film It is clear that the same effect can be obtained, and the influence of noise between the mounted electronic component and the wiring layer is not a problem, and there is no problem between the mounted electronic component and the wiring layer and other electronic components. In order to eliminate the influence of noise, the shield layer is formed so as to shield noise between the mounted electronic component and the wiring layer and other electronic components.

(Embodiment 2)
FIG. 5 is a diagram illustrating a configuration other than the slit 6 according to the second embodiment, and FIG. 6 is a diagram illustrating a configuration in the slit 6.

  As shown in FIG. 5, the configuration of the FPC 2 other than the slit 6 of the present embodiment includes a base film 12 that is a base material of the FPC 2, a mounting electronic component such as an LCD panel that is formed in an upper layer of the base film 12, and A wiring layer 13 for electrically connecting a control circuit such as a cellular phone, an overcoat layer (upper) 14 for insulating the wiring layer 13, and a lower layer of the base film 12 from the mounted electronic component and the wiring layer 13 It is composed of a shield layer 15 that shields emitted noise, and an overcoat layer (lower) 16 that insulates the shield layer 15.

  Further, as shown in FIG. 6, the configuration of the slits 6 of the FPC 2 has a configuration in which a plurality of slits 6 penetrating vertically through the shield layer 15 and the overcoat layer (lower) 16 are provided. The area includes a base film 12 serving as a base material of the FPC 2, a wiring layer 13 formed on the base film 12 and electrically connected to a mounting electronic component such as an LCD panel and the control circuit, and the wiring layer 13 And an overcoat layer (upper) 14 that insulates.

  According to the present embodiment, it is generated between the mounted electronic component and wiring layer 13 on the overcoat layer (upper) 14 side, and other electronic components disposed on the overcoat layer (lower) 16 side. Noise is shielded from each other by the shield layer 15, and the flexibility reduced by forming the shield layer 15 in the wiring layer is improved by the slit 6 provided in the shield layer 15 and the overcoat layer 16 in the bending range. When the FPC is bent in this range, it can be easily bent from the straight line on which the slits 6 are arranged. The shape, the number, and the arrangement relationship of the slits 6 are determined in consideration of bending at the time of mounting of components and the like and after mounting.

  Next, as a first embodiment of the present invention, a more specific configuration example of the FPC that forms an enlarged pattern of the shield layer enlarged from the wiring pattern on the upper wiring layer of the base film will be described.

  7A and 7B are diagrams showing the configuration of the FPC of this example. FIG. 7A is a cross-sectional view of the FPC bending range excluding the overcoat layer, and FIG. 7B is a front view (top view) of the FPC shield layer side. is there.

  In the FPC of this example, as shown in FIGS. 7A and 7B, the first wiring layer (1) is formed in the lower layer of the base film, and the second wiring layer (2) is formed in the upper layer. At the same time, a shield layer 17 having an enlarged pattern of the same metal as the wiring layer (2) is formed on the same layer as the wiring layer (2), and electronic components such as LCD drive circuit components (not shown) are mounted. A plurality of slits 6 are formed in the shield layer 17 in the range and arranged in a plurality of rows on a plurality of parallel straight lines whose longitudinal direction is the crease direction (left-right direction in FIG. 7). The shield layer 17 can be formed as an enlarged pattern electrically connected to the ground wiring or the like of the wiring layer (2).

  The lowering of the flexibility of the folding range due to the formation of the enlarged pattern of the shield layer is improved by the plurality of rows of slits. Further, unlike the shield layer, the region of the wiring layer (2) in the bent range has substantially the same flexibility as the region of the enlarged pattern of the shield layer in which the slits 6 exist due to the presence of wiring between which the metal is not formed. In the case where the flexibility of the wiring layer (2) is insufficient, the slit 6 is also formed in the overcoat layer (upper) (not shown) above the wiring layer (2). It is effective to form a plurality of straight slits in the same manner as in FIG.

  FIG. 8 is a view showing a second embodiment in which slits are also formed in the overcoat layer of the wiring layer (2). FIG. 2 is a front view of the FPC 2 having an overcoat layer 18. In this embodiment, the slit 6-1 is formed in the enlarged pattern 17, and the overcoat layer 18 on the wiring layer (2) outside the range of the enlarged pattern 17 is also formed. A slit 6-2 is formed to match the flexibility of the folding range of both regions. The adjustment of the flexibility of both areas of the bending range can be set by the size of the enlarged pattern 17, the number of slits, the number of arrays, the slit shape, and the size.

  As an example of the material used for each layer of the FPC, polyimide is used for the base film, copper is used for the wiring layers (1) and (2) and the shield layer, and polyimide is used for the overcoat layer (upper) and lower. As a method for producing the shield layer, a metal paste material (silver paste) can be applied to the base film. However, a method for forming a wiring pattern on the base film of the FPC is used to produce a wiring layer (2 ) Can be applied in the same process of manufacturing a shield layer having a slit to the same layer at the same time, and an additional manufacturing process for forming the shield layer is not required and the shield An increase in cost due to the formation of the layer can be avoided.

It is a figure which shows the structure of a LCD module, and the side surface of the state which bent FPC of 1st Embodiment. It is a figure which shows the front of the state which expand | deployed FPC of FIG. It is a figure which shows the cross section of the BB site | part of FPC2 in FIG. It is a figure which shows the cross section of the AA site | part of FPC2 in FIG. It is a figure which shows the structure other than the slit 6 of 2nd Embodiment. It is a figure which shows the structure in the slit 6 of 2nd Embodiment. It is a figure which shows the structure of FPC of the 1st Example of this invention, (a) is sectional drawing except the overcoat layer of the bending range of FPC, (b) is the same front view by the side of the shield layer of FPC. . FIG. 8 is a view showing a second embodiment in which slits are also formed in the overcoat layer of the wiring layer (2). It is a figure which shows the structural example of the flexible printed wiring board of a prior art example.

Explanation of symbols

1 LCD panel 2 FPC (Flexible Printed Circuit)
3 LCD drive circuit component 4 LCD module 5 FPC 2 bending range 6, 6-1, 6-2 Slit 7, 12, 121, 131, 110A Base film 8, 13, 123, P Wiring layer 9, 16 Overcoat layer ( under)
10, 15, 110E, 200 Shield layer 18 Overcoat layer (top)
17 Enlarged pattern

Claims (8)

A flexible printed wiring board having a wiring layer on an upper layer side and a lower layer side of a base film,
A flexible printed wiring, wherein an enlarged pattern is formed on either the upper layer side or the lower layer side to form a shield layer, and a plurality of slits in the crease direction are arranged in the folding range of the shield layer. substrate. The flexible printed wiring board according to claim 1, wherein the plurality of slits are arranged in a plurality of rows. The flexible printed wiring board according to claim 1, further comprising an overcode layer on an outer side of the wiring layer, wherein the same-shaped slit overlapping the slit is arranged in a bending range of the overcode layer. . 4. The flexible printed wiring board according to claim 1, wherein a wiring pattern is formed in an external area of the enlarged pattern. 5. The flexible printed wiring board according to claim 3, wherein slits are arranged in a fold direction in a folding range of an overcoat layer on the upper layer of the wiring pattern. The flexible printed wiring board according to claim 1, wherein the shield layer is formed in the same process as the wiring layer. 7. The flexible printed wiring board according to claim 1, wherein an electronic component is mounted on the enlarged pattern. 8. The flexible printed wiring board according to claim 7, wherein the electronic component is an LCD drive circuit component, and an LCD panel is connected to one end of the substrate.

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