JP2013045823A - Rigid flex printed wiring board equipped with bending holding function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rigid flex printed wiring board capable of easily holding a bent state of a flexible region.SOLUTION: A rigid flex printed board is partially equipped with a bendable flexible region. The board includes: a flexible printed wiring board which is composed of at least a flexible substrate, a wiring pattern formed on the flexible substrate, and a cover lay for protecting the wiring pattern; and an island-shaped rigid dummy board which is provided on an outer layer of the flexible region in the flexible printed wiring board.

Description

  The present invention relates to a rigid flex printed wiring board having a flexible region that can be bent in part, and more particularly to a rigid flex printed wiring board capable of holding the flexible region in a desired bent state.

  In recent years, with the progress of miniaturization of equipment, the installation space of printed wiring boards installed in the equipment has become smaller and more complex, and for this reason, rigid printing installed in equipment By dividing the wiring board (hereinafter simply referred to as “printed wiring board”) for each function and connecting the divided printed wiring boards with a flexible printed wiring board having a high degree of freedom of installation, It corresponds to the space.

  Also, in terminal connection means for printed wiring boards and flexible printed wiring boards, the mainstream connector connection is switched to solder connection or ACF (anisotropic conductive film) connection to reduce the size of the equipment. Further promotion is also underway.

  By the way, the flexible printed wiring board has the convenience that it can be bent freely, and at the same time has very high elasticity. Accordingly, as shown in FIG. 11A, when the connection terminals (not shown) of the printed wiring boards P1 and P2 arranged on the non-straight line are connected by the flexible printed wiring board FP, the bent portion 23 is the original. The terminal connection portion 22 (for example, a printed wiring board) connected with a repulsive force (sometimes referred to as “spring back”) to return to a position always works, and the stress is connected via solder or ACF. As a result of continuing to act in the direction (the direction indicated by the arrow shown in the figure) to peel off the connection portion between the connection terminals provided on the flexible printed wiring board), it will eventually cause a connection failure. In rare cases (see FIG. 11B showing a state in which the connection terminal 2b of the flexible printed wiring board FP is peeled from the terminal connection portion 22).

  Therefore, means for suppressing such a repulsive force and maintaining the bent state of the flexible printed wiring board are disclosed in Patent Documents 1 to 3, for example.

  FIG. 12 is a schematic cross-sectional view of the flexible printed wiring board FP disclosed in Patent Document 1, and includes a wiring pattern 2 made of a band-shaped or linear solderable metal material, and the wiring pattern 2. A cover lay 5 that covers both sides of the cover lay, a cover lay removal portion 5a provided at an intermediate portion of the one cover lay 5, and a solder 24 attached on the wiring pattern 2 exposed from the cover lay removal portion 5a. The flexible printed wiring board FP is bent at the portion where the solder 24 is adhered, and the return of the bent portion 23 is suppressed (that is, the bent state is maintained).

  FIG. 13 shows a configuration of a flexible printed wiring board FP disclosed in Patent Document 2, and includes a flexible substrate 1, a wiring pattern 2 formed on the surface of the flexible substrate 1, and the wiring pattern 2. A first cover lay 5b that protects the metal plate 25, a metal plate 25 disposed on the first cover lay 5b, and a second cover lay 5c that holds the metal plate 25. The wiring board FP is bent at a bending line 26 shown in FIG. 13B, and the bent state is maintained by plastic deformation of the metal plate 25.

  FIG. 14 is a schematic cross-sectional view for explaining the method for maintaining the shape of the flexible printed wiring board FP disclosed in Patent Document 3. First, the flexible printed wiring board is connected between the printed wiring boards P1 and P2. The board assembly 27 connected by the FP is installed by using the stopper 29 so that the printed wiring boards P1 and P2 are at the same angle as that in the actual product, and then the flexible printed wiring board. The flexible printed wiring board FP is held in a bent state by fitting the FP into a bending die 28 having a curved surface 28a and performing heat forming.

However, the configurations of Patent Documents 1 to 3 have the following problems.
That is, in the configuration of Patent Document 1, since the removal portion 5a of the coverlay 5 provided in the bent portion 23 needs to be removed according to the shape of the wiring pattern 2, the manufacturing process is very complicated, and the removal When the formation position of the part 5a is shifted, there is a concern that a short circuit failure may occur between the adjacent wiring patterns 2.

  Moreover, in the structure of patent document 2, the process which arrange | positions the metal plate 25 one sheet at a bending part is required (when the flexible printed wiring board FP is small, the metal plate 25 is desired. In addition, it is necessary to provide an extra metal plate 25 that is not originally required and an expensive second cover lay 5c that holds the metal plate 25, which is costly. Was also a disadvantageous composition.

  The configuration of Patent Document 3 requires a dedicated stopper 29 and a bending die 28 for each product in order to maintain the bent state of the flexible printed wiring board FP, which is a very laborious and costly construction method. there were.

  In addition, as a common problem of Patent Documents 1 to 3, there is one that guards a soft flexible material (flexible substrate, cover lay) in spite of having a certain length in any configuration. Since nothing is provided, the flexible printed wiring board FP is used for a housing in a product application that is required to be installed in a very narrow space, such as a portable device, and that is frequently subjected to vibration. There is also a concern that it may be damaged by rubbing with a printed wiring board or an electronic component installed inside or inside the device.

JP 2006-128525 A JP 2006-165079 A JP 2006-319097 A

  The present invention does not require a new component material such as a solder or a metal plate or a bending die as means for holding the flexible region (bending region of the flexible printed wiring board) in a desired bent state, and is easily flexible. Rigid flex print that can maintain the folded state of the area and does not cause damage to the flexible area even when it is installed in an environment where the flexible area is rubbed against the inside of the housing due to frequent vibrations It is an object to provide a wiring board.

  The present invention relates to a rigid flex printed wiring board having a flexible region that can be bent in part, and includes at least a flexible substrate, a wiring pattern formed on the flexible substrate, and a cover layout for protecting the wiring pattern. The above-mentioned problem is solved by a rigid flex printed wiring board comprising: a flexible printed wiring board comprising: and an island-shaped rigid dummy board provided in an outer layer of the flexible region of the flexible printed wiring board. Is.

Since the rigid flex printed wiring board of the present invention has an island-shaped rigid dummy board arranged in the outer layer of the flexible region, the exposed area of the flexible printed wiring board in the flexible region is intermittent and small. As a result of the repulsive force generated in the bent portion being dispersed, the bent state of the flexible region can be maintained. Moreover, as a means for intermittently reducing the exposed area of the flexible printed wiring board, an island-shaped rigid dummy board made of a constituent material of a normal rigid flex printed wiring board is simply arranged, so that the flexible area can be easily bent. The state can be maintained.
Since the rigid area is provided with a rigid dummy board in the flexible area, even if the flexible area is rubbed against the inside of the housing due to vibration, the dummy board serves as a guard, and the flexible flexible printed wiring board Can protect from damage.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic cross-sectional explanatory drawing which shows 1st embodiment of the rigid-flex printed wiring board of this invention. The schematic cross-section explanatory drawing which shows 2nd embodiment of the rigid-flex printed wiring board of this invention. The schematic cross-section manufacturing process figure which shows the manufacture example of the rigid flex printed wiring board of 1st embodiment. The schematic cross-section manufacturing process figure which shows the manufacture example of the rigid flex printed wiring board of 2nd embodiment. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective explanatory view showing a bent holding state of a rigid flex printed wiring board of the present invention. (A) is schematic sectional drawing explanation which shows the example of arrangement | positioning structure of the dummy board in case a bending part is one place, (b) is schematic sectional explanatory drawing which shows the arrangement | positioning structural example of the dummy board in the case of bending in S shape. The principal part expanded cross-section manufacturing process figure which shows the manufacture example in the case of providing a shield pattern in the dummy board of the rigid flex printed wiring board of FIG. FIG. 3 is an enlarged cross-sectional explanatory diagram of a main part when a shield pattern is provided on a dummy board of the rigid flex printed wiring board of FIG. 2. FIG. 3 is a main part enlarged cross-sectional manufacturing process diagram showing a manufacturing example in the case where the shield pattern is provided on the dummy plate of the rigid flex printed wiring board of FIG. 1 and the shield pattern is not exposed from the side surface of the dummy plate. (A) is an enlarged cross-sectional explanatory view of a main part when the shield pattern is provided on the dummy plate of the rigid flex printed wiring board of FIG. 2 and the shield pattern is not exposed from the side surface of the dummy plate. ) Is an enlarged plan view of the main part when the residual pattern on the dummy plate is viewed from above. (A) is a schematic cross-sectional explanatory view showing a state in which a conventional flexible printed wiring board is bent and connected between two printed wiring boards, and (b) is one connection terminal due to the repulsive force of the flexible printed wiring board. The schematic cross-section explanatory drawing which showed the state peeled from the terminal connection part. Schematic cross-sectional explanatory drawing which shows the structure of the conventional flexible printed wiring board. (A) is schematic sectional explanatory drawing which shows the structure of the other conventional flexible printed wiring board, (b) is the same schematic plan explanatory drawing. Schematic cross-sectional explanatory drawing which shows the bending state maintenance method of the conventional flexible printed wiring board. The schematic cross-section explanatory drawing which shows the malfunction at the time of laminating | stacking what provided the opening part in the part corresponded beforehand to the exposed area of a flexible printed wiring board as an insulating layer.

A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a schematic cross-sectional view of a rigid flex printed wiring board of the present invention. The rigid flex printed wiring board RFP is formed on a flexible substrate 1 having flexibility and one surface of the flexible substrate 1. The wiring pattern 2, the cover lay 5 that protects the wiring pattern 2, the low elastic modulus material layer 4 formed between the wiring pattern 2 and the cover lay 5, and later the rigid flex printed wiring board RFP. A flexible printed wiring board FP comprising a connection terminal 2b provided in a portion corresponding to the terminal area T at the time; an island-like rigid provided in the outer layer of the flexible area F that can be bent in the flexible printed wiring board FP; It has a configuration having a dummy plate 9. In the present embodiment, since the dummy plate 9 is arranged in an island shape on the outer layer of the flexible region F, the exposed area 10 of the flexible printed wiring board FP in the flexible region F is intermittent and small, so that the flexible region F As a result, the repulsive force generated in the bent portion of the flexible region F is dispersed, so that the bent state of the flexible region F can be maintained in a desired bent state, and connection reliability when connected to a connection terminal provided on another printed wiring board, etc. Can be secured.

Incidentally, the low elastic modulus material layer 4 shown in the figure is a residue remaining when the rigid flex printed wiring board RFP of the present embodiment is manufactured in the manufacturing process shown in FIG. 3, and is an essential constituent material of the present invention. is not. As will be described later in the manufacturing process, the low elastic modulus material layer 4 is made of a thermosetting resin in which an elastomer is contained in an epoxy resin, and is originally very thin and has a followability between wiring patterns. It is often used from the past for the purpose of improving the adhesion between the wiring pattern and the insulating layer laminated thereon.
Therefore, although it is a by-product, when the connection terminal 2b is subjected to the gold plating process, it is possible to prevent the problem that the gold plating process liquid penetrates into the boundary portion between the cover lay 5 and the connection terminal 2b. Therefore, even if it exists in the rigid flex printed wiring board RFP, there is no particular obstacle.

Next, a manufacturing example for obtaining the rigid flex printed wiring board RFP of FIG. 1 will be described using the schematic cross-sectional manufacturing process diagram shown in FIG.
First, as shown in FIG. 3A, a flexible substrate 1 (a flexible insulating substrate made of polyimide, polyethylene terephthalate, liquid crystal polymer, etc., for example, “SB, MB” manufactured by Nippon Steel Chemical Co., Ltd., Ube Nitto Kasei Co., Ltd. Metal foil 2a (generally “copper foil”) is used on one side of “BE, BR” manufactured by Mitsui Chemicals, Inc. and “NFX, NEX” manufactured by Mitsui Chemicals, Inc. For example, “3EC manufactured by Mitsui Metal Mining Co., Ltd.” -III "," JTC "manufactured by JX Nippon Mining & Metals Co., Ltd.," GTS "manufactured by Furukawa Electric Co., Ltd., etc.) are prepared, and then a circuit is formed on the metal foil 2a ( The wiring pattern 2 is formed by applying a known “subtractive method” (see FIG. 3B).

  Next, the exposed surface of the wiring pattern 2 is roughened by performing a soft etching process (for example, a soft etching process using formic acid or an amine-based complexing agent as a main component, for example, “MEC Co., Ltd .: CZ8100”). 3 (b), the low elastic modulus material layer 4 and the wiring pattern 2 are protected on the wiring pattern 2 forming surface side of the single-sided flexible substrate 3 on which the wiring pattern 2 is formed. Coverlay 5 (for example, the one having an epoxy adhesive on the adhesive surface side of an insulating substrate such as polyimide mentioned in the description of “flexible substrate 1”) is sequentially arranged, and then heated and pressurized By forming each constituent material integrally by treatment (temperature: 160 to 190 ° C., pressure: 3 MPa, time: 60 to 90 minutes), the flexible printed wiring board F in FIG. Obtained.

  Here, the low elastic modulus material layer 4 may be any material as long as it can prevent damage to the wiring pattern 2 that becomes the connection terminal 2b in the blasting process to be performed later. And an elastomer (“elastomer” is an elastic polymer such as a synthetic rubber such as silicon rubber, which has the effect of imparting elasticity to a resin such as epoxy) (for example, Mitsui Metals) ("Primer resin" manufactured by the company) and the like are preferable, and in particular, if it has an elastic modulus of 3 GPa or less, excessive cutting by blasting can be surely prevented, so that the low elastic modulus material layer 4 This is preferable for reducing the thickness. In addition, since the low elastic modulus material layer 4 is originally unnecessary in the product, thinning the printed wiring board and facilitating desmear treatment (desmear removal of the blast relaxation layer 4) are as thin as possible. To preferred.

  Next, a semi-cured insulating adhesive in which a reinforcing fiber such as a glass woven fabric or a glass nonwoven fabric is impregnated with a thermosetting resin such as an epoxy resin on both surfaces of the flexible printed wiring board FP shown in FIG. Layer (corresponding to “insulating layer 6” obtained by curing the “insulating adhesive layer”. As the insulating adhesive layer (prepreg), “R-1661, R-1551” manufactured by Panasonic Electric Works Co., Ltd., Hitachi Chemical The metal foil 2a is laminated via “GEA-67N, GEA-67BE” manufactured by the company) (temperature: 180 to 190 ° C., pressure: 3 MPa, time: laminated for 60 to 90 minutes) Alternatively, a resin-coated metal foil 7 in which the two are integrated in advance is laminated (see FIG. 3D), and then an etching resist and brass are formed on a portion where the dummy plate 9 is to be formed later on the outer layer of the flexible region F. The resist layer 8 having both the resist, for example, be formed by, for example, exposed and developed laminated dry film resist on the metal foil 2a (see FIG. 3 (e)).

Next, the metal foil 2a exposed from the resist layer 8 is removed by etching (for example, etching using an etchant such as “ferric chloride solution” and “cupric chloride solution”) (FIG. 3 (f)), and then the insulating layer 6 exposed by the etching process is removed by sand blasting or wet blasting (see arrow BL shown in FIG. 3 (g)). A state substrate is obtained.
The flexible substrate 1 and the coverlay 5 are not protected by the resist layer 8 or the low elastic modulus material layer 4, but polyimide or the like used for these is originally a low elastic modulus material, so there is no protective layer. Both can withstand blasting sufficiently.

  Next, after peeling off the resist layer 8 with a sodium hydroxide solution or the like (see FIG. 3 (i)), the metal foil 2a exposed by removing the resist layer 8 is removed by etching (see FIG. 3 (j)). Next, the exposed blast relaxation layer 4 is removed by a desmear process (for example, a desmear process such as a sodium permanganate type or a potassium permanganate type), and then subjected to outer shape processing, thereby forming a terminal region T at both ends. The island-shaped rigid dummy board 9 (residual insulation of the insulating layer 6) which makes the exposed area 10 of the flexible printed wiring board FP intermittent and small on both outer layers of the flexible area F which has the connection terminals 2b and can be bent. A rigid flex printed wiring board RFP on which a dummy board 9) made of the layer 6a is arranged is obtained (see FIG. 3 (k)).

  The point to be noted in the present embodiment is that the flexible region is bent by providing an island-shaped rigid dummy plate on the outer layer of the flexible region, and making the exposed area of the flexible printed wiring board in the flexible region intermittent and small. In addition to making it possible to maintain the state, the island-shaped rigid dummy plate is formed of a constituent material of a normal rigid-flex printed wiring board.

  Thereby, since the said dummy board can be formed by the manufacturing process of a normal rigid flex printed wiring board, the rigid flex printed wiring board provided with the bending holding function of the flexible area | region can be obtained easily. In addition, since the flexible area is guarded by a rigid dummy board, the flexible flexible printed wiring board can be protected from damage.

  Incidentally, although the reason why the flexible region F can be held in a desired bent state is not certain, as shown in FIG. 5, when the flexible region F of the rigid flex printed wiring board RFP is bent, the flexible printed wiring board FP It is considered that the flexible material (flexible substrate or coverlay) slightly extends on the surface A on the convex side in each exposed area 10 and keeps the state as it is (reference sign “shown in the drawing” “B” indicates a “surface on the concave side” corresponding to the “surface A on the convex side”).

Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 2 is a schematic cross-sectional view of the rigid flex printed wiring board of the present invention. The rigid flex printed wiring board RFP includes a flexible substrate 1 having flexibility and wiring formed on both surfaces of the flexible substrate 1. A four-layer flexible printed wiring board FP comprising a pattern 2 and a wiring pattern 2 laminated on a forming surface of the wiring pattern 2 via a flexible substrate 1a made of the same material as the flexible substrate 1; In the wiring board FP, an outer layer wiring pattern 2 having a connection terminal 2b in a part laminated via an insulating layer 6 in a portion corresponding to the rigid region R when the rigid flex printed wiring board RFP is later formed, Blind via hole 14 connecting the wiring patterns 2 adjacent to each other This is expressed as “BVH”), through-plating through-holes 16 that can be connected to the wiring patterns 2 in all layers, a solder resist pattern 18 that partially protects the wiring patterns 2 in the outer layer, and a flexible region F includes a rigid dummy plate 9a formed in an island shape (a dummy plate 9a including a residual pattern 17 and a residual insulating layer 6a stacked on the residual pattern 17). In the present embodiment, since the dummy plates 9a are arranged in an island shape, the exposed area 10 of the flexible printed wiring board FP in the flexible region F is intermittent and small, and thus occurs in the bent portion of the flexible region F. As a result of the repulsive force being dispersed, the bent state of the flexible region F can be maintained in a desired bent state.

  Then, the manufacture example for obtaining the rigid flex printed wiring board RFP of FIG. 2 is demonstrated using the schematic cross-section manufacturing-process figure shown in FIG. In addition, since it is the same about the constituent material and process conditions which are common in 1st embodiment, the description is abbreviate | omitted.

  First, as shown in FIG. 4 (a), a double-sided flexible board 3a in which metal foils 2a are laminated on both sides of the flexible board 1 is prepared, and then a circuit pattern is formed on the metal foil 2a to form a wiring pattern. 2 is formed (see FIG. 4B).

  Next, after the exposed surface of the wiring pattern 2 is roughened by performing a soft etching process, the same material as that of the flexible board 1 is used on both sides of the double-sided flexible board 3a in a state where the wiring pattern 2 is roughened. One-sided flexible substrate 3b with an adhesive layer (for example, “MCF-5000I” manufactured by Hitachi Chemical Co., Ltd.), Kyocera (Such as “TFA-504” manufactured by Chemical Co., Ltd.) is applied to the wiring pattern 2 provided on the double-sided flexible substrate 3a and the adhesive-formed surface of the single-sided flexible substrate 3b with an adhesive layer facing each other. Are integrally formed (see FIG. 4C).

  Next, as shown in FIG. 4D, after a portion of the metal foil 2a at the BVH formation scheduled portion is removed by etching to form the window portion 11, a laser is applied to the flexible substrate 1a exposed from the window portion 11. By irradiating (for example, “carbon dioxide laser”), the non-through hole 12 reaching the lower wiring pattern 2 is drilled (see FIG. 4E), and then the non-through hole is formed by performing a desmear process. After removing the resin residual film (carbonized film) remaining on the lower wiring pattern 2 by leveling of the inner wall 12 and laser irradiation, electroless plating treatment (for example, “electroless copper plating treatment”), electrolytic plating treatment ( For example, by sequentially performing “electrolytic copper plating process”), the plating film 13 is deposited, and the non-through holes 12 are made conductive (see FIG. 4F).

  Next, by forming a circuit on the conductor (conductor made of the metal foil 2a and the plating film 13) formed on the outer layer of the substrate of FIG. 4 (f), the flexibility when the rigid flex printed wiring board RFP is formed later. A laser receiving pattern 2c (a metal pattern for preventing a hole from being formed in the lower flexible substrate 1a during laser processing to be performed later) and a wiring pattern 2 are formed in a portion corresponding to the region F. (See “Flexible Printed Circuit Board FP” of 4 layers (number of layers of the wiring pattern) shown in FIG. 4G), and then on both sides of the flexible printed circuit board FP as shown in FIG. Then, after sequentially laminating the insulating layer 6 and the metal foil 2a (or laminating the metal foil with resin 7 in a state where both are laminated in advance), an etching process is performed to prepare the BVH formation. Window portion 11 in part, respectively to form a window portion 11a in the counterbore (spot facing) scheduled portion of the insulating layer 6 provided in the flexible region F (see FIG. 4 (i)).

  Next, by irradiating the insulating layer 6 exposed from each of the window parts 11 and 11a with a laser (for example, “carbon dioxide laser”), the non-through hole 12 and the counterbore part 12b are drilled, and then a through plating through hole is to be formed. The through hole 15 is drilled by drilling the portion (see FIG. 4 (j)), and after cleaning each hole by desmear treatment, a plating film is formed on the entire outer layer including the inside of each hole. By depositing 13 (for example, a plating film comprising “electroless copper plating” and “electrolytic copper plating”), a substrate in the state of FIG. 4K is obtained.

  Next, as shown in FIG. 4L, by forming a circuit by a known subtractive method, the outer layer wiring pattern 2 and the inner layer wiring pattern 2 vertically adjacent to the outer layer wiring pattern 2 are formed. BVH 14 connecting between them and through-plating through hole 16 corresponding to connection between wiring patterns of all layers are formed, and residual pattern 17 (residue of laser receiving pattern 2c) and residual remaining on residual pattern 17 are formed. An island-shaped rigid dummy plate 9a made of an insulating layer 6a (residue of the insulating layer 6) is formed on both outer layers of the flexible region F, and then a solder resist pattern 18 that partially protects the outer wiring pattern 2 is formed. After forming, the outer region is processed so that the rigid regions R at both ends are connected by a four-layer flexible printed wiring board FP, and A rigid flex printed wiring board RFP is obtained in which island-shaped rigid dummy boards 9a for intermittently reducing the exposed area 10 of the flexible printed wiring board FP are disposed on both outer layers of the bendable flexible region F (FIG. 4). (See (m)).

The point to be noted in the present embodiment is obtained by a very general printed wiring board manufacturing process as compared with the first embodiment that requires a blasting process using a low elastic modulus material layer. It is in the point made into the structure made.
As a result, the rigid flex printed wiring board RFP of the present invention can be obtained more easily and at a lower cost than those of the first embodiment.

In describing the present invention, as an example of the arrangement of the dummy plate 9, an example in which the dummy plate 9 is arranged on both the front and back outer layers of the flexible region F and the exposed area 10 of the flexible printed wiring board FP is overlapped on the front and back surfaces is shown. It is not necessary to provide the outer and outer layers of the flexible region F, and if only the folding holding function is considered, any one of the outer layers (preferably a bent portion having a high possibility of coming into contact with another printed wiring board or the like is projected. Even if it is disposed only on the surface on the side that becomes the shape, it is sufficiently possible to maintain the bent state.
However, as described in the first and second embodiments, from the viewpoint of reducing warpage occurring in the manufacturing process or protecting both surfaces from damage when bent into an S shape, the flexible region It is preferable to provide it on both front and back outer layers of F.

  Moreover, although the example which arrange | positions the thing of the same magnitude | size by the front and back both outer layers as a size of the dummy board 9 was shown, as shown to Fig.6 (a), when a flexible area | region is bent, it becomes a concave side. If the dummy plate 9 provided on the surface B is made smaller than the dummy plate 9 provided on the convex surface A (that is, the exposed area 10 of the flexible printed wiring board FP on the concave surface B is increased). ), The bending load applied to the flexible printed wiring board FP when the flexible region is bent can be reduced (that is, the disconnection failure of the wiring pattern 2 in the bent portion can be suppressed), and further, FIG. As shown, the flexible region can be easily folded (folded) by combining the places where the dummy plates 9 of the same size are arranged on the front and back outer layers and the places where the dummy plates 9 of different sizes are arranged. It is possible to hold the lower load relief while) S-shape.

  Also, if a shield pattern is provided on the dummy plate and the shield pattern and the ground pattern formed on the flexible printed wiring board are connected via BVH, a shield material such as a shield film is newly provided on the outer layer of the flexible region. Intrusion of noise can be easily suppressed.

Incidentally, such a shield pattern can be formed as follows.
First, as an example provided in the first embodiment, a non-through hole is formed at a position where a dummy plate 9 is to be formed later on the substrate in FIG. 7A (corresponding to an enlarged cross-sectional view of the main part in FIG. The ground pattern 2d formed on the flexible printed wiring board FP is exposed by perforating 12a (for example, perforating by laser processing) (see FIG. 7B).

  Next, after the inside of the non-through hole 12a is cleaned by a desmear process, an electroless plating process and an electrolytic plating process are sequentially performed to deposit a plating film 13 (see FIG. 7C), and then FIG. As shown in d), the conductor (conductor made of the metal foil 2a and the plating film 13) exposed from the resist pattern 8 is removed by etching (corresponding to FIG. 3 (f)).

Next, as shown in FIG. 7E, after the insulating layer 6 exposed from the resist pattern 8 is removed by performing a blast process (corresponding to FIG. 3H), the resist pattern 8 and then forming a solder resist pattern 18 that protects the exposed shield pattern 19 (for example, the solder resist is applied to the entire surface by electrostatic spraying and temporarily dried (semi-cured), and then exposed. The shield pattern 19 connected to the ground pattern 2d via the BVH 14a can be formed in the formation portion of the dummy plate 9 (see FIG. 7F). ).
In this configuration, since the shield pattern 19 is formed on the outer layer of the dummy plate 9, unlike the configuration of FIG. 1, it is necessary to form the solder resist pattern 18 for protecting the shield pattern 19. Become. In addition, the shield pattern 19 is exposed from the side surface of the dummy plate 9, but this can be solved by depositing a gold plating film on the portion in the nickel-gold plating process applied to the connection terminal 2b. .

In addition, as shown in FIG. 9, it is possible to adopt a configuration in which the shield pattern 19 is not exposed from the side surface of the dummy plate 9.
Briefly, after preparing the same substrate as FIG. 7C (see FIG. 9A), the shield pattern 19 is formed inside the outer shape of the surface area of the dummy plate 9 finally obtained. Then, the etching resist pattern 8a is formed, and then the conductor exposed from the etching resist pattern 8a (the conductor made of the metal foil 2a and the plating film 13) is removed by etching (see FIG. 9B).

  Next, after peeling off the etching resist pattern 8a, the exposed surface (surface and side surface) of the exposed shield pattern 19 and its periphery (corresponding to the size of the finally obtained dummy plate) are covered with the resist pattern 8 ( Next, the insulating layer 6 exposed from the resist pattern 8 is removed by blasting (see FIG. 9D), and then the resist pattern 8 is peeled off and exposed to the shield pattern. By covering 19 with the solder resist pattern 18, the shield pattern 19 can be configured not to be exposed from the side surface of the dummy plate 9 (see FIG. 9E).

Next, although it is an example provided in 2nd embodiment, in this case, in the process of FIG.4 (d)-FIG.4 (g), the dummy board in the laser receiving pattern 2c is formed simultaneously with forming BVH14. The BVH 14a is formed also in the formation portion of 9a, and thereafter, the same process as that in FIGS. 4H to 4M is performed, so that the dummy pattern 9a is connected to the formation portion of the dummy plate 9a via the ground pattern 2d and the BVH 14a. The shield pattern 19 thus formed can be formed (see FIG. 8).
In this configuration as well, the shield pattern 19 is exposed from the side surface of the dummy plate 9a. However, as in the configuration of FIG. 7, if a gold plating film is deposited during the nickel-gold plating process applied to the connection terminal 2b. Good.

In addition, as shown in FIG. 10, it is also possible to adopt a configuration in which the shield pattern 19 is not exposed from the side surface of the dummy plate 9a.
In this case, when a circuit is formed on the substrate (four-layer flexible printed wiring board FP) in which the BVH 14a is formed on the formation portion of the dummy plate 9a described above (see FIGS. 4F and 4G). Correspondingly, a slit 20 is provided inside the outer shape of the surface area of the dummy plate 9a, and the residual pattern 17 can be easily dealt with by separating it into a shield pattern 19 and an outer peripheral pattern 21 unrelated to the circuit (FIG. 10 ( a) and (b)).

  In describing the present invention, the first and second embodiments have been described as examples. However, the configuration of the present invention is not limited to this, and other configurations are possible as long as they do not depart from the configuration of the present invention. Of course, it can also be used for configuration.

  Also in the manufacturing method for obtaining the rigid flex printed wiring board of each embodiment, as a method other than the steps shown in FIGS. 3 and 4, for example, a method of laminating the insulating layer 6, the flexible printed wiring board FP is previously provided. A method of laminating an insulating resin layer (also in a semi-cured state before the insulating layer 6 is cured: a so-called prepreg) provided with an opening in a portion corresponding to the exposed area 10 is also possible.

  However, in this method, as shown in FIG. 15, when the insulating resin layer is laminated, the resin of the insulating resin layer flows into the exposed area 10 of the flexible printed wiring board FP, and the dummy plate 9 ( 9a) and the flexible printed wiring board FP are formed with the resin bleed portion 30 as a result of which it becomes difficult to maintain the bent state of the exposed area 10 (in the case of the dummy plate 9a, the bleed portion 30 is an etching resist). Thus, the bottom of the residual pattern 17 that is a constituent material of the dummy plate 9a is widened. Therefore, not only is it difficult to maintain the bent state, but the bottom of the residual pattern 17 becomes a blade-like presence, and the flexible region There is also a concern that the flexible printed wiring board FP may be cut when F is bent), or Since the edge resin layer is in a semi-cured state, it may be difficult to align the opening with the position of the exposed area 10 of the flexible printed wiring board FP. Therefore, the insulating layer 6 may be blasted or laser processed. It can be said that it is preferable to select the process of FIGS. 3 and 4 for forming the exposed area 10 of the flexible printed wiring board FP by sitting down (this does not cause the problem of the bleeding part 30).

DESCRIPTION OF SYMBOLS 1, 1a: Flexible substrate 2: Wiring pattern 2a: Metal foil 2b: Connection terminal 2c: Laser receiving pattern 2d: Ground pattern 3: Single-sided flexible substrate 3a: Double-sided flexible substrate 3b: Single-sided flexible substrate with adhesive layer 4: Low elastic modulus Material layer 5: Cover lay 5a: Removal portion 5b: First cover lay 5c: Second cover lay 6: Insulating layer 6a: Residual insulating layer 7: Metal foil with resin 8: Resist pattern 8a: Etching resist pattern 9, 9a: Dummy plate 10: Exposed area 11, 11a: Window portion 12, 12a: Non-through hole 12b: Counterbore portion 13: Metal plating 14, 14a: BVH
15: Through hole 16: Through plating through hole 17: Residual pattern 18: Solder resist pattern 19: Shield pattern 20: Slit 21: Peripheral pattern 22: Terminal connection part 23: Bending part 24: Solder 25: Metal plate 26: Bending line 27: Board assembly 28: Bending die 28a: Curved surface 29: Stopper 30: Bleeding portion FP: Flexible printed wiring board RFP: Rigid flex printed wiring board R: Rigid area F: Flexible areas P1, P2: Printed wiring board A: Convex Surface B on the shape side: Surface on the concave side

Claims (4)

  A rigid flex printed wiring board having a flexible region that can be bent in part, and comprising at least a flexible substrate, a wiring pattern formed on the flexible substrate, and a coverlay that protects the wiring pattern A rigid flex printed wiring board comprising: a printed wiring board; and an island-shaped rigid dummy board provided in an outer layer of the flexible region of the flexible printed wiring board.   2. The rigid flex according to claim 1, wherein the dummy plate is provided on both front and back outer layers of the flexible region, and the exposed area of the flexible printed wiring board is overlapped on both the front and back outer layers. Printed wiring board.   3. The rigid according to claim 2, wherein the exposed area of the flexible printed wiring board that is overlapped by both the front and back outer layers is exposed in a wider area than the convex side when the flexible area is bent. Flex printed circuit board.   The rigid flex printed wiring board according to claim 1, wherein the dummy board has a shield pattern connected to a ground pattern formed on the flexible printed wiring board.