JP2006140278A - Method of manufacturing rigid-flex multilayered printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the delamination of a shield layer formed on the surface of an internal-layer flexible substrate from the internal-layer flexible substrate during manufacturing processes, in a method of manufacturing a rigid-flex multilayered printed wiring board which is composed of a flexible portion having flexibility and a rigid portion wherein an electronic component is mounted. <P>SOLUTION: The shield layer 2 is formed on the region of the internal-layer flexible substrate 1 which becomes the flexible portion. Then, on the internal-layer flexible substrate 1 and the shield layer 2, an external-layer rigid board 5 is pasted having degassing holes 4 formed above the shield layer 2. Outgas generated from the shield layer 2 is exhausted through the degassing holes 4. Then, the external-layer rigid board 5 pasted on the shield layer 2 is removed from on the shield layer 2 to form the rigid-flex multilayered printed wiring board. <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 flexible portion can be bent, and the rigid portion is excellent in component mounting. Such rigid-flex multilayer printed wiring boards are used as internal wiring boards for various electronic devices.

  To manufacture such a rigid-flex multilayer printed wiring board, first, as shown in FIG. 3A, a circuit pattern is formed on the surface conductor of the inner layer CCL 103a to protect the circuit of the inner layer CCL 103a. A cover lay 103 b is laminated as an insulating layer to form an inner layer FPC (inner layer flexible substrate) 103. The number of inner layers is not limited. 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. Then, as shown in FIG. 3C, an outer layer rigid plate (RPC) 105 is bonded onto the surfaces of the inner layer FPC 103 and the shield layer 104. The outer layer rigid plate 105 is provided with a slit that forms the outer edge of the shield layer 104. Further, as shown in FIG. 3D, an outermost layer substrate (outermost layer FPC) 106 in which a region corresponding to the shield layer 104 is punched is laminated on the outer layer rigid plate 105.

  Then, as shown in FIG. 3 (e), the outer layer rigid board 105 is cut at the slits, and the outer layer rigid board 105 on the shield layer 104 is removed, thereby producing a rigid flex multilayer printed wiring board.

  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 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.

Further, Patent Document 9 describes a configuration in which the thickness of the hinge portion is made thinner than the circuit thickness of the rigid flex board in a multilayer wiring board having a rigid flex structure.
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, when a part of the shield layer 104 formed on the surface of the inner layer FPC 103 removes the outer layer rigid board 105, the outer layer rigid board is used. Since it adheres to the 105 side, there is a problem that it is peeled off from the inner layer FPC 103 together with the outer layer rigid plate 105.

  The reason why such a phenomenon occurs is considered as follows. That is, after the shield layer 104 is formed, the outer layer rigid plate 105 and the outermost layer substrate 106 are laminated, and therefore, it is necessary to perform press working. In this press working, the entire wiring board is heated, so outgas may be generated from the shield layer 104. This outgas is mainly composed of a low molecular weight substance forming the shield layer 104, and after adhering to the surface of the outer layer rigid plate 105, it is solidified by a temperature drop, so that a part of the shield layer 104 is removed from the outer layer rigid plate 105. Adhere to the 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) that is not laminated only by the inner layer FPC 103. 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 process in which the outer layer plate is laminated on the inner layer FPC 103 having a single layer or a plurality of layers and the shield layer 104 is being formed is in the middle. In the manufacture of the rigid-flex multilayer printed wiring board made in, the peeling of the shield layer 104 from the inner layer FPC 103 when the outer layer rigid board 105 is removed cannot be prevented.

  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 multilayer wiring board having a rigid flex structure, but only describes that the thickness of the hinge portion is made thinner than the circuit thickness of the laminated rigid flex board. Yes, this technique cannot prevent the shield layer 104 from being peeled off 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. Provides a method of manufacturing a rigid-flex multilayer printed wiring board in which the shield layer formed on the surface of the inner layer flexible substrate having a single layer or a plurality of layers is not peeled off from the inner layer flexible substrate during the manufacturing process. There is to do.

  Another object of the present invention is to provide a rigid flex that can reduce the occurrence of internal stress and distortion of the substrate during the heating process when manufacturing a so-called bag-shaped rigid flex multilayer printed wiring board having no shield layer. It is providing the manufacturing method of a multilayer printed wiring board.

  In the manufacturing method of 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, an inner layer flexible substrate, a shield layer, an outer layer rigid plate, etc. The inventors have obtained knowledge that the above-described problems can be solved by removing and discharging outgas generated from the shield layer during lamination.

  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 constituted by a flexible portion having flexibility and a rigid portion on which electronic components are mounted, the step of forming a circuit pattern on a conductor on the inner layer CCL; A step of bonding a coverlay on the inner layer CCL to form an inner layer flexible substrate, a step of forming a shield layer on a region to be a flexible portion of the inner layer flexible substrate, a shield layer on the inner layer flexible substrate and the shield layer A step of bonding an outer layer rigid plate having a slit forming an outer edge of the outer layer and a gas vent hole located on the shield layer; a step of cutting the outer layer rigid plate in the slit and removing the outer layer rigid plate on the shield layer from the shield layer; It is characterized by having.

[Configuration 2]
In the manufacturing method of the rigid-flex multilayer printed wiring board having the configuration 1, the inner layer flexible board is after the step of attaching the outer layer rigid board and before the step of removing the outer layer rigid board on the shield layer from the shield layer. The substrate, the shield layer, and the outer layer rigid plate are heated.

  In the manufacturing method of the rigid-flex multilayer printed wiring board according to the present invention, even if outgas is generated from the shield layer during the manufacturing process, this outgas is removed through the vent hole provided in the outer layer rigid board. And discharged.

[Configuration 3]
A method of manufacturing a rigid flex multilayer printed wiring board constituted by a flexible portion having flexibility and a rigid portion on which electronic components are mounted, the step of forming a circuit pattern on a conductor on the inner layer CCL; A step of bonding a coverlay on the inner layer CCL to form an inner layer flexible substrate, and a step of bonding an outer layer rigid plate having a slit forming the outer edge of the flexible portion and a vent hole located on the flexible portion on the inner layer flexible substrate. And a step of cutting the outer layer rigid plate at the slit and removing the outer layer rigid plate on the flexible portion from the flexible portion.

  In the method of manufacturing a rigid-flex multilayer printed wiring board according to the present invention, when manufacturing a so-called bag-structured rigid-flex multilayer printed wiring board having no shield layer, generation of internal stress or distortion of the substrate during the heating process Can be reduced.

  In the manufacturing method of the rigid flex multilayer printed wiring board according to the present invention, even if outgas is generated from the shield layer during the manufacturing process, the outgas is generated by providing a gas vent hole in the outer layer rigid board. It is removed and discharged through the vent hole. Therefore, in this rigid flex multilayer printed wiring board manufacturing method, the shield layer formed on the surface of the inner flexible board may be peeled off from the inner flexible board when the outer rigid board is removed during the manufacturing process. Absent.

  In addition, the manufacturing method of the rigid-flex multilayer printed wiring board according to the present invention is a method of manufacturing a so-called bag-structured rigid-flex multilayer printed wiring board that does not have a shield layer. Generation can be reduced.

  That is, the present invention is a method for manufacturing a rigid-flex multilayer printed wiring board composed of a flexible portion having flexibility and a rigid portion on which electronic components are mounted, and is formed on the surface of an inner-layer flexible substrate. It is possible to provide a method for manufacturing a rigid-flex multilayer printed wiring board in which the shield layer is not peeled off from the inner-layer flexible substrate during the manufacturing process, and a so-called bag-structured rigid-flex multilayer print having no shield layer. In the case of manufacturing a wiring board, it is possible to reduce the occurrence of internal stress and distortion of the substrate during the heating process.

  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 CCL1a. Then, a coverlay 1c is bonded to both surfaces of the inner layer CCL1a as an insulating layer for protecting the circuit of the inner layer CCL1a to form an inner layer flexible substrate (FPC) 1. When a plurality of inner layers CCL1a are used, the inner layers CCL1a are stacked, and then a coverlay 1c is bonded to both surfaces of the plurality of inner layers CCL1a to form an inner layer flexible substrate (FPC) 1.

  The inner layer CCL1a is formed of, for example, a material having flexibility, heat resistance, and insulation, such as polyimide resin, and a copper foil or the like is deposited and formed as a conductor 1b on one or both surfaces. It is what. The coverlay 1c is formed of a material having flexibility, heat resistance, and insulation, such as polyimide resin, and an adhesive layer is formed on one surface. When a plurality of inner layers CCL1a are stacked, the inner layers CCL1a are stacked via an adhesive layer and joined to each other.

  Next, as shown in FIG. 1B, the shield layers 2 are formed on the upper and lower surfaces of the region to be the flexible portion 101 in the inner layer flexible substrate 1. This shield layer 2 is formed as a synthetic component containing a low molecular weight substance.

  Then, as shown in FIG. 1C, an outer layer rigid plate (RPC) 5 having a slit 3 and a vent hole 4 is bonded onto the inner layer flexible substrate 1 and the upper and lower surfaces of the shield layer 2. The outer layer rigid plate 5 is formed of a hard, heat-resistant and insulating material such as glass-epoxy material, for example, and a conductor is deposited on one or both surfaces. It 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. The vent hole 4 is formed so as to be located on the shield layer 2.

  Next, as shown in (d) of FIG. 1, the outermost layer substrate (outermost layer FPC) 6 is laminated on the upper and lower surfaces of the outer layer rigid plate 5. The outermost substrate 6 has an opening formed by punching a region corresponding to the shield layer 2. That is, the outermost substrate 6 is laminated only in a region that becomes the rigid portion 102.

  As described above, when the outer layer rigid plate 5 and the outermost layer substrate 6 are laminated after the shield layer 2 is formed, press working is performed. In this pressing, the entire wiring board is heated and pressurized. At this time, the shield layer 2 may generate an outgas whose main component is a low molecular weight substance contained in the shield layer 2. However, this outgas is quickly removed and discharged through the gas vent hole 4 provided in the outer layer rigid plate 5. Therefore, in this manufacturing method, the outgas generated from the shield layer 2 does not adhere to the outer layer rigid plate 5 and solidify due to a temperature drop, and the shield layer 2 does not adhere to the outer layer rigid plate 5 side.

  Then, as shown in FIG. 1 (e), the outer layer rigid board 5 is cut at the slit 3 and the outer layer rigid board 5 on the shield layer 2 is removed, whereby a rigid flex multilayer printed wiring board is produced.

[Other Embodiments of the Invention]
The present invention is not limited to the purpose of preventing peeling of the shield layer as described above, but is also applied to a method of manufacturing a rigid-flex multilayer printed wiring board having a structure without a shield layer, that is, a multilayer printed wiring board generally called a bag structure. Is possible. In this case, it is possible to prevent excessive internal stress and distortion from being generated in the substrate due to expansion of the hollow portion of the bag structure during heating.

  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 four-layer rigid flex multilayer printed wiring board was prepared using a double-sided FPC as the inner layer CCL and a single-sided RPC as the outer layer rigid board.

  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 and dimensions without any particular limitation.

  In this example, the substrate size was 340 mm × 250 mm, the thickness of the polyimide substrate in the inner layer 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 CCL, a polyimide substrate having a thickness of 25 μm provided with an adhesive layer having a thickness of 25 μm 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, carbon black was applied at 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 single-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.

  The diameter of the vent hole provided in the outer layer rigid plate is 0.1 mm in Example (1), 0.2 mm in Example (2), 0.3 mm in Example (3), Example In (4), 0.5 mm, in Example (5), 1.0 mm, in Example (6), 2.0 mm, in Example (7), 3.0 mm, in Example (8), 5 mm. 0.0 mm.

  In these examples, a rigid flex multilayer printed wiring board was prepared by the following procedure. That is, first, circuit patterns were formed on the conductors on both sides of the inner layer CCL. Next, a cover lay was laminated on both surfaces of the inner layer CCL, bonded by heating and pressurizing, and the adhesive was cured to obtain an inner layer flexible substrate (FPC). And the shield ink was apply | coated to the area | region used as the flexible part on this inner layer flexible substrate, and the shield layer was formed.

  On the other hand, an outer layer rigid board was punched into a predetermined shape using a mold. In this outer layer rigid board, a slit was provided at the outer edge of the region corresponding to the flexible portion, and a gas vent hole was provided in the region corresponding to the flexible portion. Then, an adhesive sheet was laminated on the surface of the outer layer rigid plate on which the glass epoxy substrate was exposed.

  And this outer layer rigid board was laminated | stacked and adhered with respect to the inner-layer flexible board | substrate by overlapping on an inner-layer flexible board | substrate, and heating and pressurizing. 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 board, the outer layer rigid board was cut at a slit, and the region corresponding to the flexible portion of the outer layer rigid board was removed from the shield layer. .

[Comparative Example]
In this comparative example, a four-layer rigid flex multilayer printed wiring board was prepared using a double-sided FPC as the inner layer CCL and a single-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, the outer layer rigid plate was not provided with a gas vent hole. 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 substrate when the outer rigid board on the shield layer was removed was examined. The presence or absence of such peeling is shown in [Table 1] below.

  In this [Table 1], “◯” indicates that there was no peeling of the shield layer, “Δ” indicates that there was very little peeling of the shield layer, and “×” indicates that the shielding layer was peeled off. This indicates that there was peeling. As can be seen from [Table 1], in [Comparative Example] in which no vent hole was provided, a part of the shield layer was peeled off from the inner flexible board when the outer rigid board was removed, and transferred to the outer rigid board. Was.

  In the rigid-flex multilayer printed wiring boards in Examples (3) to (8) provided with the gas vent holes, no peeling of the shield layer was observed when the outer-layer rigid board was removed. However, in Example (2) where the diameter of the vent hole is 0.2 mm, the shield layer is peeled off in some points, and in Example (1) where the diameter of the vent hole is 0.1 mm The shield layer was peeled only by about 1/5 the area of the comparative example. Therefore, it was found that when the diameter of the gas vent hole is small, the outgas generated from the shield layer is insufficiently released and the shield layer is peeled when the outer rigid plate is removed.

[Other Embodiments of the Invention]
In this example, the present invention was applied to a method of manufacturing a rigid flex multilayer printed wiring board having a structure without a shield layer, that is, a multilayer printed wiring board generally called a bag structure. As a result, it was possible to prevent excessive internal stress and distortion from occurring on the substrate due to expansion of the hollow portion of the bag structure during heating.

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 flexible substrate 1a Inner layer CCL
1b conductor 1c coverlay 2 shield layer 3 slit 4 vent hole 5 outer layer rigid plate 101 flexible part 102 rigid part

Claims (3)

A manufacturing method of a rigid flex multilayer printed wiring board constituted by a flexible portion having flexibility and a rigid portion on which an electronic component is mounted,
Forming a circuit pattern on a conductor on the inner layer CCL;
Bonding the coverlay on the inner layer CCL to form an inner layer flexible substrate;
Forming a shield layer on a region to be the flexible portion in the inner layer flexible substrate;
Bonding an outer layer rigid board having a slit that forms an outer edge of the shield layer and a vent hole located on the shield layer on the inner layer flexible substrate and the shield layer;
Cutting the outer layer rigid board at the slit and removing the outer layer rigid board on the shield layer from the shield layer. A method of manufacturing a rigid flex multilayer printed wiring board, comprising:   After the step of bonding the outer layer rigid plate, and before the step of removing the outer layer rigid plate on the shield layer from the shield layer, the inner layer flexible substrate, the shield layer, and the outer layer rigid plate The manufacturing method of the rigid-flex multilayer printed wiring board of Claim 1 characterized by the above-mentioned. A manufacturing method of a rigid flex multilayer printed wiring board constituted by a flexible portion having flexibility and a rigid portion on which an electronic component is mounted,
Forming a circuit pattern on a conductor on the inner layer CCL;
Bonding the coverlay on the inner layer CCL to form an inner layer flexible substrate;
Bonding an outer layer rigid board having a slit forming the outer edge of the flexible part and a vent hole located on the flexible part on the inner layer flexible substrate;
Cutting the outer-layer rigid board at the slit and removing the outer-layer rigid board on the flexible part from the flexible part. A method for producing a rigid-flex multilayer printed wiring board, comprising:

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