JP2006156576A - Method of manufacturing rigid flex multilayer printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent peeling of a shield layer formed on the front surface of an internal layer flexible substrate therefrom during the manufacturing process in the manufacturing method of rigid flex multilayer printed wiring board constituted with a rigid portion having the flexible property and a rigid portion where electronic components are mounted. <P>SOLUTION: A shield layer 2 is formed on an area which becomes a flexible portion on an internal layer flexible substrate 1 and an external layer rigid plate 5 is stacked on the internal layer flexible substrate 1 and shield layer 2. The area corresponding to this external layer rigid plate 5 and shield layer 2 is formed thinner with the etching process so that the shield layer 2 is no longer in contact with the external layer rigid plate 5. The rigid flex multilayer printed wiring board is completed by removing, from the shield layer 2, the external layer rigid plate 5 on the shield layer 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present proposal relates to a method of manufacturing a rigid flex (R-F) multilayer printed wiring board constituted by a flexible portion having flexibility and a rigid portion on which electronic components are mounted.

  2. Description of the Related Art Conventionally, as shown in FIG. 2, there has been proposed a rigid flex (R-F) multilayer printed wiring board including a flexible portion 101 having flexibility and a rigid portion 102 on which electronic components are mounted. In this rigid-flex multilayer printed wiring board, the rigid portion is excellent in component mountability. Such rigid-flex multilayer printed wiring boards are used as internal wiring boards for various electronic devices.

  In order to manufacture such a rigid-flex multilayer printed wiring board, as shown in FIG. 3A, a circuit pattern is formed on the surface conductor of the inner-layer flexible CCL 103a. Then, cover lays 103b are bonded to both surfaces of the inner layer flexible CCL 103a to form an inner layer FPC (inner layer flexible substrate) 103. Further, when using a plurality of inner-layer flexible CCLs 103a, after laminating these inner-layer flexible CCLs 103a together with the insulating layer of the circuit, all of the circuits having circuits in the flexible part of the plurality of inner-layer flexible CCLs 103a The coverlay 103b is bonded to the surface.

  Next, as shown in FIG. 3B, a shield layer 104 is formed in a region to be the flexible portion 101 in the inner layer FPC 103. The shield layer 104 is formed by applying a shield material (shield ink). Then, as shown in FIG. 3C, an outer layer rigid plate (RPC) 105 is bonded to the surface of the inner layer FPC 103 and the shield layer 104 via an adhesive sheet. The outer layer rigid plate 105 is composed of a substrate and conductors formed on both surfaces of the substrate. In addition, a circuit pattern is formed on the surface to which the adhesive sheet is bonded before being bonded. The outer rigid plate 105 is provided with a slit that forms the outer edge of the shield layer 104. Then, holes (through holes) for conducting the conductors of the respective layers are provided, copper plating is formed on the substrate surface and in the holes, and a circuit pattern is formed on the conductors of the outer rigid plate 105. Further, as shown in FIG. 3D, a resist layer 106 is formed in a region that becomes the rigid portion 102 on the outer layer rigid plate 105.

  Then, as shown in FIG. 3 (e), the outer layer rigid board 105 is cut at the slit, and the outer layer rigid board 105 on the shield layer 104 is removed from the shield layer 104, thereby completing the rigid flex multilayer printed wiring board. To do.

  Conventionally, various proposals have been made for a printed wiring board that approximates or is related to such a rigid flex multilayer printed wiring board. For example, in Patent Document 1, on a shield layer having a thickness of 5 μm or less, It is described that by providing an adhesive layer and a fixed insulating layer, good shielding characteristics can be obtained without impairing flexibility.

  Further, in Patent Document 2, in a flexible wiring board that requires flexibility, a conduction hole is provided on the upper surface of the earth circuit pattern, and the conduction hole is filled with a conductive adhesive. It is described that the layers are electrically connected.

  Further, Patent Document 3 describes a structure in which a first cover lay, a shield layer, and a second cover lay are stacked in order on a circuit pattern.

  And in patent document 4, in the flexible wiring board comprised by laminating | stacking an insulating film, an adhesive agent, a circuit pattern, an adhesive agent, a metal film, and an insulating film in this order, the arbitrary locations and metal films of a circuit pattern A structure that is conducted by a conductive paste is described.

  In Patent Document 5, an insulating resin layer having an opening is provided on a circuit pattern, and after metal plating is performed on the opening, a conductive coating such as silver paste is applied, and an insulating resin layer is further formed on the opening. The structure which provides is described.

  Patent Document 6 describes that the total thickness of the wiring board is reduced by providing a shield layer only at a necessary portion on the upper and lower surfaces of the double-sided wiring board.

  Patent Document 7 describes a configuration in which an upper portion of an exposed surface of a circuit pattern is covered with an insulating film, and a shield layer is further provided on the insulating film.

  Patent Document 8 describes that, in a multilayer wiring board having a rigid flex structure, a shield layer is not provided at a location where a through hole exists.

Patent Document 9 describes a configuration in which a hinge portion is thinner than a laminated inner layer FPC in a rigid-flex multilayer wiring board.
JP-A-5-3395 Japanese Patent Laid-Open No. 6-224587 Japanese Patent Laid-Open No. 7-122882 JP-A-7-283579 JP 11-177192 A JP 2002-176231 A JP 2004-119604 A JP 7-79089 A JP-A-7-106766

  In the case of manufacturing a rigid-flex multilayer printed wiring board as described above, a part of the shield layer 104 formed on the surface of the inner layer FPC 103 adheres to the outer layer rigid board 105 side, and the outer layer rigid board 105 When this is removed, there is a problem that the outer layer rigid plate 105 and the inner layer FPC 103 are peeled off.

  The reason why such a phenomenon occurs is considered as follows. That is, after the shield layer 104 is formed, it is necessary to perform press working in order to stack the outer layer rigid plate 105. In this pressing, the constituent material is pressurized. For this reason, the shield layer 104 and the outer layer rigid board 105 come into physical contact, and a part of the shield layer 104 adheres to the outer layer rigid board 105 side.

  Patent Documents 1 to 7 described above all relate to a single-layer plate structure (single-sided plate structure or double-sided plate structure) in which the inner-layer flexible CCL 103a is not laminated. In manufacturing a rigid-flex printed wiring board having such a single-layer board structure, it is necessary to consider protecting the shield layer during the manufacturing process because the shield layer can be processed after all the processing has been completed. There is no.

  Therefore, by using the techniques described in Patent Documents 1 to 7, a rigid-flex multilayer printed wiring in which a plurality of inner layer flexible CCLs 103a are stacked and the shield layer 104 is formed in the middle of the process. In manufacturing the plate, it is not possible to prevent the shield layer 104 from being peeled off from the inner layer FPC 103 when the outer layer rigid plate 105 is removed.

  Further, Patent Document 8 describes a technique related to a rigid-flex structure multilayer wiring board, but only describes that a shield layer 104 is not provided at a through hole in a circuit pattern. Depending on the condition, peeling of the shield layer 104 from the inner layer FPC 103 cannot be prevented.

  Furthermore, Patent Document 9 describes a technique related to a rigid-flex structure multilayer wiring board, but only describes that the thickness of the hinge portion is made thinner than the thickness of the laminated inner layer FPC. This technique cannot prevent the shield layer 104 from peeling from the inner layer FPC 103.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to produce a rigid-flex multilayer printed wiring board composed of a flexible portion having flexibility and a rigid portion on which electronic components are mounted. The present invention provides a method for manufacturing a rigid-flex multilayer printed wiring board in which the shield layer formed on the surface of the inner layer FPC is prevented from being peeled off from the inner layer FPC during the manufacturing process.

  In the manufacturing method of a rigid-flex multilayer printed wiring board configured by a flexible part having flexibility and a rigid part on which an electronic component is mounted, the inventors prevent the shield layer and the outer-layer rigid board from contacting each other. As a result, the inventors have obtained knowledge that the above-mentioned problems can be solved.

  That is, the manufacturing method of the rigid flex multilayer printed wiring board according to the present invention comprises at least one of the following configurations.

[Configuration 1]
A method of manufacturing a rigid-flex multilayer printed wiring board composed of a flexible portion having flexibility and a rigid portion on which an electronic component is mounted, the step of forming a circuit pattern on a conductor on the inner layer CCL, and an inner layer A step of bonding a coverlay to the CCL, a step of forming a shield layer by applying a shielding material on a region to be a flexible portion of the inner layer flexible substrate (inner layer FPC) to which the coverlay is bonded, and an inner layer flexible substrate And a step of bonding an outer layer rigid board having a circuit pattern formed on the surface of the substrate to be bonded to the inner layer flexible substrate made of a substrate and a conductor formed on the shield layer, and further having a slit forming the outer edge of the shield layer And cut the outer layer rigid plate at the slit on the shield layer Removing the layer rigid plate, and before bonding the outer layer rigid plate on the inner layer flexible substrate and the shield layer, the thickness of the region corresponding to the shield layer of the outer layer rigid plate is reduced by etching. It is characterized by keeping.

[Configuration 2]
In the manufacturing method of the rigid-flex multilayer printed wiring board having configuration 1, the outer-layer rigid board corresponds to the shield layer of the outer-layer rigid board in the etching process for the outer-layer rigid board before being bonded to the inner-layer flexible substrate and the shield layer. It is characterized by removing the area.

  In the manufacturing method of the rigid-flex multilayer printed wiring board according to the present invention, the shield layer and the outer-layer rigid board do not come into contact with each other. Therefore, when the region corresponding to the shield layer of the outer-layer rigid board is removed, By adhering to the outer layer rigid board side, it does not peel from the inner layer flexible substrate.

  In the method of manufacturing the rigid-flex multilayer printed wiring board according to the present invention, the region corresponding to the shield layer of the outer layer rigid board is thinned or removed by the etching process, so that the shield layer and the outer layer rigid board are in contact with each other. Without removing the outer layer rigid plate during the manufacturing process, the shield layer is not peeled off from the inner layer flexible substrate.

  That is, the present invention relates to a method for manufacturing a rigid-flex multilayer printed wiring board composed of a flexible portion having flexibility and a rigid portion on which an electronic component is mounted. However, the manufacturing method of the rigid-flex multilayer printed wiring board which was made not to peel from an inner-layer flexible substrate during a manufacturing process can be provided.

  The best mode for carrying out the present invention will be described below with reference to the drawings. As shown in FIG. 2, the manufacturing method of the rigid-flex multilayer printed wiring board according to the present invention includes a rigid-flexible (R) composed of a flexible portion 101 having flexibility and a rigid portion 102 on which electronic components are mounted. -F) A manufacturing method for manufacturing a multilayer printed wiring board.

  FIG. 1 is a cross-sectional view showing a manufacturing process of a rigid flex multilayer printed wiring board according to an embodiment of the present invention.

  The manufacturing method of this rigid-flex multilayer printed wiring board has the following processes. That is, in this manufacturing method, first, as shown in FIG. 1A, a circuit pattern is formed on the conductor 1b on the inner layer CCL1c. Then, cover lays 1d are bonded to both surfaces of the inner layer CCL1c to form an inner layer FPC (inner layer flexible substrate) 1. When a plurality of inner layers CCL1c are used, the inner layers CCL1c are laminated together with a circuit insulating layer, and then a cover lay 1d is bonded to all surfaces having circuits in the flexible portion of the plurality of inner layers CCL1c. .

  The resin base material 1a of the inner layer CCL1c is formed of, for example, a material having flexibility, heat resistance, and insulation, such as polyimide resin. On one or both surfaces, a copper foil or the like is used as the conductor 1b. It is formed by deposition. The cover lay 1d is formed of a material having flexibility, heat resistance, and insulation, such as polyimide resin, and an adhesive layer is formed on one surface. In the case where there are a plurality of inner layers CCL1c, the inner layers CCL1c are stacked via an adhesive layer and bonded to each other.

  Next, as shown in FIG. 1B, a shielding material is applied to the surfaces of the upper and lower surfaces of the region to be the flexible portion 101 in the inner layer CCL1c formed and laminated with the circuit pattern, thereby forming the shield layer 2 Form.

  Then, as shown in FIG. 1 (c), a circuit pattern is formed on the conductor on the surface to be bonded to the inner layer FPC1 on the inner layer FPC1 and the upper and lower surfaces of the shield layer 2, and the outer layer rigid having the slit 3 A plate (RPC) 5 is bonded together. The outer layer rigid plate 5 is made of, for example, a hard material having heat resistance and insulation, such as a glass-epoxy material, and a conductor 5b is formed on one or both surfaces. Is. The slit 3 of the outer layer rigid plate 5 is formed in a shape that forms the outer edge of the shield layer 2. In addition, the outer layer rigid plate 5 is formed with a concave portion 4 in a region corresponding to the shield layer 2 by an etching process before being bonded to the inner layer FPC 1 and the shield layer 2 to reduce the thickness. As this etching process, for example, various methods such as a plasma process and a chemical process can be used, and there is no particular limitation. The thickness of the outer layer rigid plate 5 after the etching process is not particularly limited, and the region corresponding to the shield layer 2 of the outer layer rigid plate 5 may be completely removed (that is, the thickness is 0).

  Then, holes (through holes) for conducting the conductors 1b of the respective layers are provided, copper plating is formed on the substrate surface and in the holes, and a circuit pattern is formed on the conductors of the outer rigid board 5. Further, a resist layer is formed in a region to be the rigid portion 102 on the outer layer rigid plate 5.

  In this way, after the shield layer 2 is formed, the outer layer rigid plate 5 is laminated by pressing. In this pressing, the entire wiring board is pressurized. At this time, since the thickness of the region corresponding to the shield layer 2 of the outer layer rigid plate 5 is reduced, the shield layer 2 and the outer layer rigid plate 5 are not in contact with each other, and the shield layer 2 is on the outer layer rigid plate 5 side. It will not stick to.

  Then, as shown in FIG. 1 (d), by cutting the outer layer rigid board 5 at the slit 3 and removing the outer layer rigid board 5 on the shield layer 2 from the shield layer 2, a rigid flex multilayer printed wiring board is obtained. Is completed. At this time, since the shield layer 2 is not in contact with the outer layer rigid plate 5, it is not peeled off from the inner layer FPC1.

  Hereinafter, the manufacturing method of the rigid-flex multilayer printed wiring board according to the present invention will be described in detail with reference to examples.

〔Example〕
In this example, a 6-layer rigid flex multilayer printed wiring board was created using a double-sided CCL as the inner layer CCL and a double-sided RPC as the outer layer rigid board.

  Note that the manufacturing method according to the present invention may use a hard RPC as the inner layer CCL, or may use a flexible CCL as the outer layer rigid plate. Furthermore, the manufacturing method according to the present invention is not limited to a rigid flex printed wiring board but can be applied to an FPC multilayer printed wiring board and an RPC multilayer printed wiring board. In addition, the manufacturing method according to the present invention can be applied to the substrate material, dimensions, and the number of layers without any particular limitation.

  In this example, the thickness of the polyimide substrate in the inner layer flexible CCL was 25 μm, the thickness of the double-sided copper foil was 18 μm, and the thickness of the adhesive layer was 10 μm. As the coverlay laminated on the inner layer flexible CCL, a 25 μm thick polyimide substrate provided with a 25 μm thick adhesive layer was used.

  Further, a silver paste was used as a shield ink for forming a shield layer, and it was applied at a thickness of about 10 μm. On this silver paste layer, a black paste was applied with a thickness of about 10 μm to form a shield layer.

  The thickness of the glass epoxy substrate in the outer layer rigid plate was 100 μm, and the thickness of the double-sided copper foil was 18 μm. As the adhesive sheet for adhering the outer layer rigid board, an adhesive sheet having a thickness of 40 μm was used.

  In this example, a rigid flex multilayer printed wiring board was prepared by the following procedure. That is, first, a circuit pattern was formed on the conductors on both sides of the inner layer flexible CCL. Next, cover lays were laminated on both sides of the inner layer flexible CCL, heated and pressed to adhere, and the adhesive was cured to form an inner layer FPC (inner layer flexible substrate). And the shield ink was apply | coated to the area | region used as a flexible part on this inner layer FPC, and the shield layer was formed.

In the outer layer rigid board, a circuit pattern was formed on the conductor on the surface to be bonded to the inner layer FPC. Furthermore, the slit was provided in the outer edge of the area | region corresponding to a flexible part. In addition, the thickness of the region corresponding to the shield layer of the outer layer rigid plate was reduced by an etching process. Etching was plasma etching. As conditions for the etching treatment, oxygen and CF ₄ were used as process gases, and the gas ratio of these process gases was 95% for oxygen and 5% for CF ₄ . Further, the treatment was performed for 30 minutes at a gas flow rate of 2 L / liter and an RF power of 2500 Watts. By the etching treatment under these conditions, the glass-epoxy substrate of the outer layer rigid plate was etched to a depth of 10 μm.

  Then, an adhesive sheet was laminated on the outer layer rigid plate. The outer layer rigid plate was laminated on the inner layer flexible substrate by being overlaid on the inner layer flexible substrate, and heated and pressurized, and adhered. Next, through-through holes were formed to provide interlayer conduction in each conductor of the outer layer rigid board and inner layer flexible board, and a circuit pattern was also formed on the conductor of the outer layer rigid board.

  A surface protective film such as a solder resist ridge was formed on the conductor of the outer layer rigid plate, and the outer layer rigid plate was cut at a slit to remove a region corresponding to the flexible portion of the outer layer rigid plate.

[Comparative Example]
In this comparative example, a 6-layer rigid-flex multilayer printed wiring board was prepared using a double-sided CCL as the inner-layer flexible CCL and a double-sided RPC as the outer-layer rigid board, as in the previous example. The substrate size and the thickness of each layer were also the same as in the example.

  However, in this comparative example, in the outer layer rigid plate, the thickness of the region corresponding to the shield layer was not reduced. Then, a rigid flex multilayer printed wiring board was prepared by the same procedure as in the example.

[Contrast between Example and Comparative Example]
With respect to the rigid flex multilayer printed wiring boards in the above-described examples and comparative examples, the presence or absence of peeling (transfer) of the shield layer from the inner flexible board accompanying removal of the outer rigid board was examined. As a result, in [Comparative Example], a part of the shield layer was peeled off from the inner flexible substrate with the removal of the outer rigid plate and transferred to the outer rigid plate. On the other hand, in the rigid-flex multilayer printed wiring board in the example, no peeling due to the removal of the outer-layer rigid board of the shield layer was observed.

It is sectional drawing which shows the manufacturing process of the rigid flex multilayer printed wiring board in embodiment of this invention. It is a perspective view which shows the structure of a rigid flex multilayer printed wiring board. It is sectional drawing which shows the manufacturing process of the conventional rigid flex multilayer printed wiring board.

Explanation of symbols

1 Inner layer FPC
1a Resin substrate 1b Conductor 1c Inner layer CCL
1d coverlay 2 shield layer 3 slit 4 recess 5 outer layer rigid plate 101 flexible portion 102 rigid portion

Claims (2)

A method for producing a rigid-flex multilayer printed wiring board constituted by a flexible portion having flexibility and a rigid portion on which electronic components are mounted,
Forming a circuit pattern on a conductor on the inner layer CCL;
Bonding a coverlay to the inner layer CCL;
A step of forming a shield layer by applying a shield material on a region to be a flexible portion in the inner layer flexible substrate to which the coverlay is bonded;
A circuit pattern is formed on the inner layer flexible substrate and on the shield layer, and a circuit pattern is formed on the surface of the substrate and a conductor to be bonded to the inner layer flexible substrate, and a slit that forms an outer edge of the shield layer is formed. Bonding the outer layer rigid board having,
Cutting the outer layer rigid plate in the slit and removing the outer layer rigid plate on the shield layer, and
Before bonding the outer layer rigid plate on the inner layer flexible substrate and the shield layer, the thickness of the region corresponding to the shield layer of the outer layer rigid plate is thinned by an etching process. Manufacturing method of rigid flex multilayer printed wiring board.   In the etching process for the outer layer rigid plate before the outer layer rigid plate is bonded to the inner layer flexible substrate and the shield layer, a region corresponding to the shield layer of the outer layer rigid plate is removed. The manufacturing method of the rigid-flex multilayer printed wiring board of Claim 1 to do.

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