JP2018200982A - Flexible printed wiring board, manufacturing method for flexible printed wiring board, and electronic equipment - Google Patents

Abstract

To provide a flexible printed wiring board capable of suppressing a radiation noise, and improving flexibility, a manufacturing method of the flexible printed wiring board, and electronic equipment.SOLUTION: The flexible printed wiring board comprises: a first conductive layer; a first insulation layer provided on the first conductive layer; a signal circuit provided on the first insulation circuit, and formed with a portion extending in one direction; a second insulation layer provided on the first insulation layer and the signal circuit; a second conductive layer provided on the second insulation layer; and a conductive slit-shaped via which penetrates from an upper surface of the second insulation layer to a lower surface of the first insulation layer for connecting the second conductive layer to the first conductive layer. The slit-shaped via has a first slit-shaped via and a second slit-shaped via formed along the signal circuit with the signal circuit interposed therebetween, and the signal circuit is arranged between the first slit-shaped via and the second slit-shaped via.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a flexible printed wiring board, a method for manufacturing a flexible printed wiring board, and an electronic device, and more particularly to a flexible printed wiring board having an electromagnetic wave shielding sheet, a method for manufacturing a flexible printed wiring board, and an electronic device.

  A flexible printed circuit board (Flexible printed circuits: FPC) is a printed circuit board in which a signal circuit or the like is formed on a flexible insulating film. For this reason, the flexible printed wiring board can be bent, and as the OA equipment, communication equipment, mobile phone, etc. in recent years become more high-performance and downsized, the inside of the casing having its narrow and complicated structure is electronic. Often used to incorporate circuits. In recent years, with the high-density mounting of electronic components due to downsizing of electronic devices and the high frequency of signals due to the increase in the amount of communication information, countermeasures against unnecessary radiation noise generated from flexible printed wiring boards have become increasingly important. ing.

  The electromagnetic shielding sheet is attached so as to be sandwiched from the upper surface and the lower surface of the flexible printed wiring board, and reduces radiation noise leaking from the flexible printed wiring board.

JP 2000-269632 A JP 2014-207297 A

  Patent Document 1 discloses a conventional flexible printed wiring board. As shown in FIGS. 19 and 20, the conventional flexible printed wiring board 101 is provided with a signal circuit 121 and a ground circuit 122 on an insulating layer 110. An insulating layer 130 is provided so as to cover the signal circuit 121 and the ground circuit 122. Furthermore, a laminated structure in which shield sheets 140 and 150 are attached to the upper surface of the insulating layer 130 and the lower surface of the insulating layer 110, respectively. The conductive layer 141 in the shield sheet 140 is connected to the ground circuit 122 through the via 160 in the through hole 161 formed in the insulating layer 130.

  In the method of attaching the electromagnetic wave shield sheets 140 and 150 as shown in the figure, radiation noise 90 leaks from the insulating layer 110 below the ground circuit 122, particularly when a high-frequency signal is passed. Since the radiation noise 90 leaked to the outside adversely affects peripheral devices, there is an increasing need to shield the signal circuit 121 three-dimensionally.

  Patent Document 2 discloses a conventional method for manufacturing a flexible printed wiring board. As shown in FIGS. 21 and 22, the conventional method of manufacturing the flexible printed wiring board 102 is as follows. (Hereinafter, referred to as double-sided FCCL) 180 is prepared (FIG. 25A).

  Next, the copper layer 120 in the double-sided FCCL 180 is processed to form the signal circuit 121 and the ground circuit 122 (FIG. 21B). Next, a cover lay 132 is formed on the insulating layer 110, the signal circuit 121, and the ground circuit 122 through the insulating adhesive layer 131 so as to cover the signal circuit 121 and the ground circuit 122 (FIG. 21C). . Next, the copper layer 124 is laminated on the cover lay 132 (FIG. 21D).

  Next, through holes 161 penetrating the copper layer 124, the cover lay 132, the insulating adhesive layer 131, the ground circuit 122, the insulating layer 110, and the copper layer 123 from the upper surface of the copper layer 124 to the lower surface of the copper layer 123. This is formed (FIG. 22A). The through holes 161 are formed along the ground circuit 122 so as to be arranged at intervals. Next, a copper plating layer 162 is formed on the upper surface of the copper layer 124, the lower surface of the copper layer 123, and the inner surface of the through hole 161 (FIG. 22B).

  Then, a cover lay 135 is formed through the insulating adhesive layer 134 so as to be sandwiched from above and below (FIG. 22C). In this way, the flexible printed wiring board 102 is formed. In such a method for manufacturing the flexible printed wiring board 102, many manufacturing steps are required, and thus the manufacturing cost increases. Moreover, since the number of laminated layers such as coverlay layers is increased, flexibility is deteriorated.

  The present invention has been made in order to solve such a problem. A flexible printed wiring board and a flexible printed circuit board that can suppress radiation noise even when a high-frequency signal is passed and can improve flexibility. A printed wiring board manufacturing method and an electronic apparatus are provided.

A flexible printed wiring board according to the present invention includes a first conductive layer, a first insulating layer provided on the first conductive layer, and a signal provided on the first insulating layer and extending in one direction. A circuit, a second insulating layer provided on the first insulating layer and the signal circuit, a second conductive layer provided on the second insulating layer, and the first insulating layer from an upper surface of the second insulating layer. A conductive slit-shaped via that penetrates to the lower surface of the layer and connects the second conductive layer and the first conductive layer, and the slit-shaped via sandwiches the signal circuit between the signal circuit and the signal circuit. A first slit-shaped via and a second slit-shaped via, and the signal circuit is provided between the first slit-shaped via and the second slit-shaped via. It is arranged.

A method for manufacturing a flexible printed wiring board according to the present invention includes a step of forming a signal circuit having a portion extending in one direction on a first insulating layer, and a second insulating layer on the first insulating layer and the signal circuit. And forming a first rectangular hole and a second rectangular hole along the signal circuit across the signal circuit, and
Attaching the surface of the electromagnetic wave shielding sheet on which the conductive adhesive is formed to the upper surface of the second insulating layer; and the conductive adhesive on the lower surface of the first insulating layer. In the first and second rectangular holes, the step of attaching the surface of the electromagnetic shielding sheet on which the conductive adhesive has been formed and the step of attaching the conductive adhesive of the electromagnetic shielding sheet by hot pressing And filling the conductive adhesive in the electromagnetic wave shielding sheet and the conductive adhesive in the first and second rectangular holes to form a first slit-shaped via and a second slit-shaped And a step of forming a via.

  The electronic device according to the present invention is one to which the flexible printed wiring board is connected.

  According to the present invention, even when a high-frequency signal is applied, leakage of radiation noise from the insulating layer provided with the signal circuit can be reliably prevented, so that radiation noise can be suppressed and flexibility can be improved. It is possible to provide a flexible printed wiring board, a manufacturing method of the flexible printed wiring board, and an electronic device that can be improved and reduced in manufacturing cost.

1 is a cross-sectional view illustrating a flexible printed wiring board according to a first embodiment. 1 is an exploded perspective view illustrating a flexible printed wiring board according to Embodiment 1. FIG. 4A to 4D are process diagrams illustrating a method for manufacturing a flexible printed wiring board according to the first embodiment. It is the figure which illustrated the electromagnetic wave shield sheet of the flexible printed wiring board concerning the modification of Embodiment 1. 6 is a cross-sectional view illustrating a flexible printed wiring board according to a second embodiment. FIG. 5 is an exploded perspective view illustrating a flexible printed wiring board according to Embodiment 2. FIG. 6 is a process end view illustrating a method for manufacturing a flexible printed wiring board according to Embodiment 2. FIG. 6 is a cross-sectional view illustrating a flexible printed wiring board according to a third embodiment. FIG. 10 is a process end view illustrating a method for manufacturing a flexible printed wiring board according to Embodiment 3. FIG. FIG. 6 is a cross-sectional view illustrating a flexible printed wiring board according to a fourth embodiment. FIG. 6 is a cross-sectional view illustrating a flexible printed wiring board according to a fifth embodiment. 10A to 10D are process diagrams illustrating a method for manufacturing a flexible printed wiring board according to the fifth embodiment. FIG. 10 is a cross-sectional view illustrating a flexible printed wiring board according to a sixth embodiment. 10 is a cross-sectional view illustrating a flexible printed wiring board according to Embodiment 7. FIG. FIG. 10 is a cross-sectional view illustrating a flexible printed wiring board according to an eighth embodiment. FIGS. 9A to 9D are process diagrams illustrating a method for manufacturing a flexible printed wiring board according to Embodiment 8. FIGS. 10 is a cross-sectional view illustrating a flexible printed wiring board according to Embodiment 9. FIG. It is sectional drawing which illustrated the flexible printed wiring board which concerns on Embodiment 10. FIG. It is sectional drawing which illustrated the flexible printed wiring board which concerns on the prior art example 1. FIG. It is the disassembled perspective view which illustrated the flexible printed wiring board concerning the prior art example 1. FIG. 10 is a process cross-sectional view illustrating a method for manufacturing a flexible printed wiring board according to Conventional Example 2. FIG. It is process drawing which illustrated the manufacturing method of the flexible printed wiring board concerning the prior art example 2, (a) And (b) shows an end elevation, (c) shows sectional drawing.

(Embodiment 1)
A flexible printed wiring board according to Embodiment 1 will be described. First, the configuration of the flexible printed wiring board will be described. FIG. 1 is a cross-sectional view illustrating a flexible printed wiring board according to the first embodiment. FIG. 2 is an exploded perspective view illustrating the flexible printed wiring board according to the first embodiment. As shown in FIGS. 1 and 2, the flexible printed wiring board 1 includes an insulating substrate layer 10 (first insulating layer), a signal circuit 21, a ground circuit 22, a cover coat layer 30 (second insulating layer), and electromagnetic waves. The shield sheet 40, the electromagnetic wave shield sheet 50, and the slit-shaped via 60 are provided. In FIG. 2, the slit-shaped via 60 is omitted. The flexible printed wiring board 1 has flexibility because it includes a film-like member, a thin member, a flexible member, and the like.

  The flexible printed wiring board 1 is formed using a single-sided flexible copper-clad laminate (hereinafter referred to as single-sided FCCL) 70 in which a copper foil is formed on one surface 11 of a film-like insulating base layer 10. . The insulating substrate layer 10 is preferably polyester, polycarbonate, polyimide, polyphenylene sulfide, or liquid crystal polymer, and more preferably liquid crystal polymer or polyimide. Among these, a liquid crystal polymer having a low relative dielectric constant and dielectric loss tangent is more preferable in consideration of the use of a flexible printed wiring board that transmits high-frequency signals. By providing such an insulating substrate, the wiring board can have high heat resistance. The circuit pattern 20 includes a ground circuit 22 for grounding and a signal circuit 21 for sending an electrical signal to an electronic component, and both are generally formed by etching a copper foil. The thickness of the circuit pattern 20 is usually about 1 to 50 μm.

  Here, in FIGS. 1 and 2, an XYZ orthogonal coordinate system is introduced for convenience of explanation. In the state where the flexible printed wiring board 1 is flattened, the direction perpendicular to the one surface 11 of the insulating base material layer 10 is taken as the Z-axis direction. Of the Z-axis directions, the direction in which one surface 11 faces is the + Z-axis direction, and the opposite direction is the −Z-axis direction. The + Z axis direction is also referred to as the upper side, and the −Z axis direction is also referred to as the lower side. One direction in a plane parallel to one surface 11, for example, the direction in which the signal circuit 21 extends in one direction is defined as the X-axis direction. One of the X-axis directions is defined as + X-axis direction, and the opposite direction is defined as -X-axis direction. A direction orthogonal to the Z-axis direction and the X-axis direction is taken as a Y-axis direction. One of the Y-axis directions is defined as + Y-axis direction, and the opposite direction is defined as -Y-axis direction.

  The ground circuit 22 is provided on the insulating base material layer 10 at a distance from the signal circuit 21. The ground circuit 22 extends in the X axis direction along the signal circuit 21. A plurality of ground circuits 22 are provided, and include, for example, a ground circuit 22a (first ground circuit) and a ground circuit 22b (second ground circuit). For example, the ground circuit 22 a is disposed on the −Y axis direction side of the signal circuit 21. The ground circuit 22b is disposed on the + Y axis direction side of the signal circuit 21. The ground circuit 22a and the ground circuit 22b have a portion provided on the insulating base material layer 10 and extending in one direction. The ground circuit 22a and the ground circuit 22b are provided so as to sandwich the signal circuit 21 from both sides on the + Y axis direction side and the −Y axis direction side. The signal circuit 21 is disposed between the ground circuit 22a and the ground circuit 22b.

  The cover coat layer 30 (second insulating layer) is provided on the insulating base material layer 10, the signal circuit 21, and the ground circuit 22. The cover coat layer 30 has a portion that covers the signal circuit 21 and the ground circuit 22. The cover coat layer 30 is an insulating material that covers the signal wiring of the wiring board and protects it from the external environment. The cover coat layer 30 is preferably a polyimide film with a thermosetting adhesive, a thermosetting or ultraviolet curable solder resist, or a photosensitive coverlay film, and more preferably a photosensitive coverlay film for fine processing. . The cover coat layer 30 generally uses a known resin having heat resistance and flexibility such as polyimide. The thickness of the cover coat layer is usually about 10 to 100 μm. In many cases, the cover coat layer 30 is provided with a part of the signal circuit and the ground circuit exposed for mounting the module and joining with the connector.

  The electromagnetic wave shielding sheet 40 is provided on the cover coat layer 30. The electromagnetic wave shielding sheet 40 includes a conductive adhesive layer 41 (second conductive layer) and an insulating layer 42 (third insulating layer), and a laminated structure in which the insulating layer 42 is provided on the conductive adhesive layer 41. It has become. The conductive adhesive layer 41 is disposed on the cover coat layer 30 side. The conductive adhesive layer 41 is provided on the cover coat layer 30. The conductive adhesive layer 41 is a conductive layer on the cover coat layer 30. The conductive adhesive layer 41 is obtained by curing the conductive adhesive of the electromagnetic wave shield sheet 40. Therefore, the electromagnetic wave shielding sheet 40 includes the conductive adhesive layer 41 and the insulating layer 42 in the flexible printed wiring board 1, and is insulated from the conductive adhesive in a single unit before becoming a member of the flexible printed wiring board 1. Layer 42.

  The electromagnetic wave shielding sheet 50 is provided below the insulating base material layer 10. The electromagnetic wave shielding sheet 50 includes a conductive adhesive layer 51 (first conductive layer) and an insulating layer 52, and has a laminated structure in which the insulating layer 52 is provided below the conductive adhesive layer 51. The conductive adhesive layer 51 is disposed on the insulating base material layer 10 side. Therefore, the insulating base material layer 10 is provided on the conductive adhesive layer 51. The conductive adhesive layer 51 is obtained by curing the conductive adhesive of the electromagnetic wave shielding sheet 50. Therefore, the electromagnetic wave shielding sheet 50 includes the conductive adhesive layer 51 and the insulating layer 52 in the flexible printed wiring board 1, and is insulated from the conductive adhesive in a single unit before becoming a member of the flexible printed wiring board 1. Layer 52.

  The insulating layer 42 is provided on the conductive adhesive layer 41. The insulating layer 52 is provided below the conductive adhesive layer 51.

Details of the conductive layer and the insulating layer will be described below.
<< Conductive adhesive layer >>
The conductive adhesive layer can be appropriately selected from an isotropic conductive adhesive layer or an anisotropic conductive adhesive layer. The isotropic conductive adhesive layer has conductivity in the vertical direction and the horizontal direction with the electromagnetic wave shielding sheet placed horizontally. The anisotropic conductive adhesive layer has conductivity only in the vertical direction with the electromagnetic wave shielding sheet placed horizontally.
The conductive adhesive layer may be either isotropic conductive or anisotropic conductive, and isotropic conductive is preferable because the connection reliability at the slit-shaped via is improved.
The conductive adhesive layer can be formed using a conductive adhesive. As the conductive adhesive, a conventionally known adhesive containing a thermosetting resin, a curing agent, and conductive fine particles can be arbitrarily used.

<Thermosetting resin>
A thermosetting resin is a resin having a plurality of functional groups capable of reacting with a curing agent. Functional groups include, for example, hydroxyl group, phenolic hydroxyl group, methoxymethyl group, carboxyl group, amino group, epoxy group, oxetanyl group, oxazoline group, oxazine group, aziridine group, thiol group, isocyanate group, blocked isocyanate group, blocked A carboxyl group, a silanol group, etc. are mentioned. Thermosetting resins include, for example, acrylic resins, maleic resins, polybutadiene resins, polyester resins, polyurethane resins, polyurethane urea resins, epoxy resins, oxetane resins, phenoxy resins, polyimide resins, polyamide resins, polyamideimide resins, phenolic resins. Known resins such as resins, alkyd resins, amino resins, polylactic acid resins, oxazoline resins, benzoxazine resins, silicone resins, and fluorine resins can be used.
Thermosetting resins can be used alone or in combination of two or more.

  Among these, polyurethane resin, polyurethane urea resin, epoxy resin, phenoxy resin, polyimide resin, polyamide resin, and polyamideimide resin are preferable from the viewpoint of flexibility.

  1-50 mgKOH / g is preferable and, as for the acid value of a thermosetting resin, 3-30 mgKOH / g is more preferable.

  The weight average molecular weight of the thermosetting resin is preferably 20,000 to 100,000.

  The content of the thermosetting resin in the solid content of the conductive adhesive layer is preferably 10 to 80% by weight, and more preferably 15 to 80% by weight.

<Curing agent>
The curing agent has a plurality of functional groups that can react with the functional groups of the thermosetting resin. Examples of the curing agent include known compounds such as an epoxy compound, an acid anhydride group-containing compound, an isocyanate compound, an aziridine compound, an amine compound, a phenol compound, and an organometallic compound.
A hardening | curing agent can be used individually or in combination with 2 or more types.

  It is preferable that 1-50 weight part of various hardening | curing agents are included with respect to 100 weight part of thermosetting resins, 3-30 weight part is more preferable, and 3-20 weight part is further more preferable.

<Conductive fine particles>
The conductive fine particles have a function of imparting conductivity to the conductive adhesive layer. The conductive fine particles are preferably, for example, conductive metals such as gold, platinum, silver, copper and nickel, and alloys thereof, and conductive polymer fine particles, and silver is more preferable from the viewpoint of cost and conductivity.
In addition, composite fine particles having a coating layer in which a metal or a resin is used as a core and the surface of the core is covered, are preferable from the viewpoint of cost reduction. Here, the core is preferably selected appropriately from inexpensive nickel, silica, copper and alloys thereof, and resins. The coating layer is preferably a conductive metal or a conductive polymer. Examples of the conductive metal include gold, platinum, silver, nickel, manganese, indium, and alloys thereof. Examples of the conductive polymer include polyaniline and polyacetylene. Among these, silver is preferable from the viewpoints of price and conductivity.

The shape of the conductive fine particles is not limited as long as desired conductivity is obtained. Specifically, for example, a spherical shape, a flake shape, a leaf shape, a dendritic shape, a plate shape, a needle shape, a rod shape, and a grape shape are preferable. Moreover, you may mix two types of electroconductive fine particles of these different shapes.
The conductive fine particles can be used alone or in combination of two or more.

  The average particle diameter of the conductive fine particles is a D50 average particle diameter, and is preferably 2 μm or more, more preferably 5 μm or more, and further preferably 7 μm or more from the viewpoint of sufficiently ensuring anisotropy. On the other hand, from the viewpoint of making the conductive adhesive layer thin, 30 μm or less is preferable, 20 μm or less is more preferable, and 15 μm or less is even more preferable. The D50 average particle diameter can be determined by a laser diffraction / scattering particle size distribution measuring apparatus or the like.

The conductive fine particles are preferably blended in an amount of 10 to 700 parts by weight and more preferably 20 to 500 parts by weight with respect to 100 parts by weight of the solid content of the thermosetting resin.
When the content is 20 to 500 parts by weight, an electromagnetic wave shielding sheet with better electromagnetic shielding properties can be obtained.

  Conductive adhesives include silane coupling agents, rust inhibitors, reducing agents, antioxidants, pigments, dyes, tackifying resins, plasticizers, UV absorbers, antifoaming agents, leveling regulators as optional components. Fillers and flame retardants can be blended.

  The conductive adhesive can be obtained by mixing and stirring the materials described so far. For the stirring, for example, a known stirring device can be used for a disperse mat, a homogenizer or the like.

  A known method can be used for producing the conductive adhesive layer. For example, a method of forming a conductive layer by applying a conductive adhesive on a peelable sheet and drying, or extruding the conductive adhesive into a sheet using an extruder such as a T-die It can also be formed.

  Coating methods include, for example, gravure coating method, kiss coating method, die coating method, lip coating method, comma coating method, blade method, roll coating method, knife coating method, spray coating method, bar coating method, spin coating method, dip coating. A known coating method such as a method can be used. In coating, it is preferable to perform a drying step. In the drying step, for example, a known drying device such as a hot air dryer or an infrared heater can be used.

  2-100 micrometers is preferable, as for the thickness of a conductive adhesive layer, 4-50 micrometers is more preferable, and 6-30 micrometers is further more preferable. When the thickness is in the range of 2 to 100 μm, it becomes easy to balance the electromagnetic shielding properties and the flexibility.

《Insulating layer》
The insulating layer can be formed using a conventionally known insulating resin composition.
The insulating resin composition can contain an optional component as necessary for the thermosetting resin and the curing agent described in the conductive adhesive. The thermosetting resin and the curing agent used for the insulating layer and the conductive adhesive layer may be the same or different.

  The insulating resin composition can be obtained by the same method as that for the conductive adhesive.

  The insulating layer may be a film formed of an insulating resin such as polyester, polycarbonate, polyimide, polyphenylene sulfide or the like.

  The thickness of the insulating layer is usually about 2 to 20 μm.

  The slit-like via 60 is provided in a rectangular hole 61 that penetrates the cover coat layer 30 and the insulating base material layer 10 between the signal circuit 21 and the ground circuit 22. Therefore, the slit-shaped via 60 penetrates from the upper surface of the cover coat layer 30 to the lower surface of the insulating base material layer 10. The slit-shaped via 60 connects the conductive adhesive layer 41 and the conductive adhesive layer 51. The slit-shaped via 60 is a first slit shape formed along the X-axis direction (one direction) between the signal circuit 21 and the ground circuit 22 a disposed on the −Y-axis direction side of the signal circuit 21. And a second slit-shaped via formed along the X-axis direction (one direction) between the signal circuit 21 and the ground circuit 22b disposed on the + Y-axis direction side of the signal circuit 21. Have. The signal circuit 21 is disposed between the first slit-shaped via 60 and the second slit-shaped via 60. The first slit-shaped via 60 is disposed between the signal circuit 21 and the ground circuit 22a, and the second slit-shaped via 60 is disposed between the signal circuit 21 and the ground circuit 22b. .

  In addition, the first slit-shaped via 60 formed in the X-axis direction on the −Y-axis side of the signal circuit 21 and the second slit-shaped via formed in the X-axis direction on the + Y-axis side of the signal circuit 21. The space between 60 and 60 is referred to as the inside surrounded by the slit-shaped via 60. On the other hand, it is formed in the X-axis direction on the −Y-axis direction side from the first slit-shaped via 60 formed in the X-axis direction on the −Y-axis side of the signal circuit 21 and on the + Y-axis side of the signal circuit 21. The + Y-axis direction side of the second slit-shaped via 60 is referred to as the outside of the slit-shaped via 60.

  The slit-like via 60 is disposed between the conductive adhesive layer 41 and the conductive adhesive layer 51. The upper end of the via 60 is in contact with the conductive adhesive layer 41, and the lower end of the slit-like via 60 is in contact with the conductive adhesive layer 51. The slit-shaped via 60 is obtained by curing the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50. Therefore, the slit-like via 60 includes the same material as the conductive adhesive layer 41 and the conductive adhesive layer 51. Therefore, the slit-like via 60 is conductive. The flexible printed wiring board 1 is a via different from the slit-shaped via 60, and connects at least one conductive adhesive layer 41 and the conductive adhesive layer 51 to the ground circuit 22. A via (not shown) is provided. Thereby, the electric adhesive layer 41 and the conductive adhesive layer 51 are connected to the ground.

Next, a method for manufacturing the flexible printed wiring board 1 according to Embodiment 1 will be described.
3A to 3C are process diagrams illustrating a method for manufacturing a flexible printed wiring board according to the first embodiment. FIGS. 3A to 3C are cross-sectional views, and FIG. 3D is an end view. As shown in FIG. 3A, first, a single-sided FCCL 70 is prepared. The single-sided FCCL 70 is obtained by forming the copper layer 20 on the insulating base material layer 10.

  Next, as shown in FIG. 3B, the circuit pattern 20 is formed by etching the copper foil layer of the single-sided FCCL 70. As a result, the signal circuit 21 having a portion extending in one direction and the plurality of ground circuits 22 a and 22 b are formed on the insulating base material layer 10. For example, the signal circuit 21 is disposed between the ground circuit 22a and the ground circuit 22b.

  Next, as shown in FIG. 3C, a cover coat layer 30 is formed on the insulating base material layer 10, the signal circuit 21, and the ground circuit 22. A cover coat layer 30 is formed so as to have a portion covering the signal circuit 21 and the ground circuit 22. When the cover coat layer 30 is formed, an insulating adhesive layer 31 is formed on one surface of the cover lay 32, and a portion that covers the signal circuit 21 and the ground circuit 22 on the surface on which the insulating adhesive layer 31 is formed is formed. The cover lay 32 is pasted so as to have it. In this manner, the cover coat layer 30 is formed on the insulating base material layer 10, the signal circuit 21, and the ground circuit 22.

  Next, as shown in FIG. 3D, a rectangular hole 61 that penetrates from the upper surface of the cover coat layer 30 to the lower surface of the insulating base material layer 10 is formed. This rectangular hole 61 is a first rectangular hole formed along the X-axis direction between the signal circuit 21 and the ground circuit 22 a disposed on the −Y-axis direction side of the signal circuit 21 so as to sandwich the signal circuit 21. And a second rectangular hole formed along the X-axis direction between the ground circuit 22b arranged on the + Y-axis direction side of the signal circuit 21 and the signal circuit 21. That is, the signal circuit 21 is formed so as to be disposed between the first rectangular hole and the second rectangular hole. As a result, the first rectangular hole and the second rectangular hole are arranged on both sides of the signal circuit 21.

  Next, the surface of the electromagnetic wave shield sheet 40 on which the conductive adhesive is formed is attached to the upper surface of the cover coat layer 30. On the other hand, the surface of the electromagnetic shielding sheet 50 on which the conductive adhesive is formed is attached to the lower surface of the insulating base material layer 10. Note that the electromagnetic shielding sheets 40 and 50 may be attached in any order, either before or after the electromagnetic shielding sheets 40 are attached. Moreover, you may stick together.

  Next, the first rectangular hole and the second rectangular hole 61 are filled with the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 by hot pressing. Thereafter, the conductive adhesive in the electromagnetic wave shielding sheets 40 and 50 and the conductive adhesive in the first rectangular hole and the second rectangular hole 61 are cured.

The hot pressing is preferably performed under conditions of a temperature of about 150 to 190 ° C., a pressure of about 1 to 3 MPa, and a time of about 1 to 60 minutes. The conductive adhesive layer and the cover coat layer are brought into close contact with each other by hot pressing, and the conductive adhesive layers of the electromagnetic wave shielding sheets 40 and 50 flow and fill each other into a rectangular hole, and then are cured, whereby conduction is obtained. When using a thermosetting resin, a thermosetting resin and a hardening | curing agent react with the heat | fever of a hot press.
In order to accelerate curing, post-cure may be performed at 150 to 190 ° C. for 30 to 90 minutes after hot pressing. In addition, an electromagnetic wave shield sheet may be called an electromagnetic wave shield layer after thermocompression bonding.

  As a result, as shown in FIGS. 1 and 2, slit-like vias 60 are formed outside the signal circuit with the signal circuit interposed therebetween, and the flexible printed wiring board 1 shown in FIGS. 1 and 2 is manufactured. .

  According to the present embodiment, the signal circuit 21 is sandwiched between the conductive slit-shaped vias 60. The slit-shaped via 60 penetrates the insulating layer 10 provided with the signal circuit 21 and connects the conductive adhesive layer 41 in the electromagnetic wave shield sheet 40 and the conductive adhesive layer 51 in the electromagnetic wave shield sheet 50. ing. Therefore, the flexible printed wiring board 1 has a structure similar to a coaxial cable in which the signal circuit 21 is three-dimensionally shielded by the upper and lower conductive adhesive layers 41 and 51 and the left and right slit-shaped vias 60. Therefore, radiation noise from the signal circuit 21 is reliably suppressed from leaking from the inside surrounded by the slit-shaped via 60 to the outside of the slit-shaped via 60 through the insulating base material layer 10 provided with the signal circuit. be able to. Therefore, the shielding of electromagnetic waves can be improved.

  Moreover, since the slit-like via 60 is formed of a conductive adhesive, the flexibility can be improved. Further, since the slit-shaped via 60 can be formed by hot pressing the electromagnetic wave shielding sheet as described above, a via forming step by copper plating as in the conventional case can be omitted, and the manufacturing process can be shortened. . In addition, since there is no need to attach a cover coat layer for ensuring insulation to the outermost layer, the flexible printed wiring board (FPC) is thinned and the flexibility is further improved.

(Modification)
Next, the flexible printed wiring board which concerns on the modification of Embodiment 1 is demonstrated.
FIG. 4 is a diagram illustrating an electromagnetic wave shielding sheet of a flexible printed wiring board according to a modification of the first embodiment. As shown in FIG. 4, in the electromagnetic wave shielding sheet 40a of the modification, instead of making the electromagnetic wave shielding sheet 40a a laminated structure of the insulating layer 42 and the conductive adhesive layer 41 shown in FIGS. The laminated structure includes a metal layer 43 provided on the adhesive layer 41 and an insulating layer 42 provided on the metal layer 43. Further, in the electromagnetic wave shielding sheet 50a (not shown but provided with a sign for easy understanding) having the same configuration as the electromagnetic wave shielding sheet 40a, instead of a laminated structure of the insulating layer 52 and the conductive adhesive layer 51, conductive The laminated structure includes a metal layer 53 provided below the adhesive layer 51 and an insulating layer 42 provided below the metal layer 53. Thereby, the electromagnetic wave shielding property at the time of flowing a high frequency signal can be improved more. The electromagnetic wave shielding sheet 40 a includes a conductive adhesive 41, an insulating layer 42, and a metal layer 43 as a single unit before becoming a member of a flexible printed wiring board. Moreover, the electromagnetic wave shield sheet 50a includes a conductive adhesive, an insulating layer 52, and a metal layer 53 as a single unit before becoming a member of a flexible printed wiring board.

  The thickness of the metal layer is preferably 0.2 to 5 μm. As for the thickness of a metal layer, 0.5-4.5 micrometers is more preferable, and 1-4 micrometers is still more preferable. When the thickness of the metal layer is in the range of 1 to 5 μm, it is possible to balance high electromagnetic shielding performance and flexibility.

As the metal layer, for example, a metal foil, a metal vapor deposition film, or a metal plating film can be used.
The metal used for the metal foil is preferably, for example, a conductive metal such as aluminum, copper, silver, or gold, more preferably copper, silver, or aluminum, and even more preferably copper from the viewpoint of electromagnetic shielding properties and cost. For example, rolled copper foil or electrolytic copper foil is preferably used as copper, and electrolytic copper foil is more preferable. When an electrolytic copper foil is used, the metal layer can be made thinner. The metal foil may be formed by plating. 1-5 micrometers is preferable and, as for the thickness of metal foil, 1.5-4 micrometers is more preferable.

The metal used for a metal vapor deposition film and a metal plating film is preferably, for example, aluminum, copper, silver, or gold, and more preferably copper or silver. The thickness of the metal vapor deposition film and the metal plating film is preferably 0.2 to 3 μm, and more preferably 0.3 to 2 μm.
The metal layer is preferably a deposited film from the viewpoint of thinning. A metal foil is preferable from the viewpoint of electromagnetic shielding properties.

  The electromagnetic wave shielding sheet 40a may be provided on the upper side, and the electromagnetic wave shielding sheet 50 may be provided on the lower side. Conversely, the electromagnetic wave shielding sheet 40 may be provided on the upper side, and the electromagnetic wave shielding sheet 50a may be provided on the lower side. Further, the present modification can be applied not only to the first embodiment but also to other embodiments described below as necessary.

(Embodiment 2)
Next, the flexible printed wiring board 2 which concerns on Embodiment 2 is demonstrated.
FIG. 5 is a cross-sectional view illustrating a flexible printed wiring board according to the second embodiment. FIG. 6 is an exploded perspective view illustrating a flexible printed wiring board according to the second embodiment. As shown in FIGS. 5 and 6, in the flexible printed wiring board 2, the slit-shaped via 60 is provided in a rectangular hole 61 that penetrates the cover coat layer 30, the ground circuit 22, and the insulating base material layer 10. Yes. The slit-shaped via 60 is provided in the X-axis direction along the ground circuit 22. That is, the slit-like via 60 also penetrates the ground circuit 22a, and penetrates the first slit-like via 60 formed in the X-axis direction (one direction) along the ground circuit 22a and the ground circuit 22b. A second slit-like via 60 formed in the X-axis direction (one direction) is provided along the ground circuit 22b. Other configurations are the same as those in the first embodiment.

Next, a method for manufacturing the flexible printed wiring board 2 will be described.
FIG. 7 is a process end view illustrating the method for manufacturing a flexible printed wiring board according to the second embodiment. First, similarly to the above-described first embodiment, the steps shown in FIGS. 3A to 3C are performed. Explanation of these steps is omitted.

  Next, as shown in FIG. 7, first and second rectangular holes 61 penetrating the cover coat layer 30, the ground circuit 22, and the insulating base material layer 10 are formed. That is, the first rectangular hole 61 is formed so as to penetrate the ground circuit 22a and to extend in the X-axis direction (one direction) along the ground circuit 22a. The second rectangular hole 61 also penetrates the ground circuit 22b and is formed in the X-axis direction (one direction) along the ground circuit 22b.

  Next, the upper surface of the cover coat layer 30 is attached with the surface of the electromagnetic wave shield sheet 40 on which the conductive adhesive is formed facing downward. On the other hand, the surface of the electromagnetic shielding sheet 50 on which the conductive adhesive is formed is attached to the lower surface of the insulating base material layer 10 with the surface facing upward. As in the first embodiment, the order in which the electromagnetic wave shielding sheets are attached may be either or simultaneously.

  Next, the first and second rectangular holes 61 are filled with the conductive adhesive in the electromagnetic wave shielding sheets 40 and 50 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 and the conductive adhesive in the first and second rectangular holes 61 are cured. The conditions for hot pressing are the same as those in the first embodiment. Thereby, as shown in FIG.5 and FIG.6, the slit-shaped via | veer 60 is formed. In this way, the flexible printed wiring board 2 shown in FIGS. 5 and 6 is manufactured.

  According to the flexible printed wiring board 2 of the present embodiment, the ground circuit 22 is included in the coaxial cable-shaped configuration including the slit-shaped via 60 surrounding the signal circuit 21 and the conductive adhesive layers 41 and 51. Therefore, it is possible to further improve the shielding of electromagnetic waves. Other effects are the same as those of the first embodiment.

(Embodiment 3)
Next, the flexible printed wiring board 3 according to Embodiment 3 will be described. In the present embodiment, the first and second rectangular holes 61 do not penetrate the ground circuit 22, and the insulating base material extends from the upper surface of the cover coat layer 30 to the upper surface of the ground circuit 22 and from the lower surface of the ground circuit 22. The bottom surface of the layer 10 is formed.

  FIG. 8 is a cross-sectional view illustrating a flexible printed wiring board according to the third embodiment. As shown in FIG. 8, in the flexible printed wiring board 3 according to the third embodiment, the first and second rectangular holes do not penetrate the ground circuit 22. The rectangular hole 61a penetrates from the upper surface of the cover coat layer 30 to the upper surface of the ground circuit 22a. The rectangular hole 61b penetrates from the lower surface of the ground circuit 22a to the lower surface of the insulating base material layer 10. The rectangular hole 61c penetrates from the upper surface of the cover coat layer 30 to the upper surface of the ground circuit 22b. The rectangular hole 61d penetrates from the lower surface of the ground circuit 22b to the lower surface of the insulating base material layer 10.

  The slit-shaped via 60a (first upper via) penetrates from the upper surface of the cover coat layer 30 to the lower surface of the cover coat layer 30, and connects the conductive adhesive layer 41 and the ground circuit 22a. The slit-shaped via 60b (first lower via) penetrates from the upper surface of the insulating base material layer 10 to the lower surface of the insulating base material layer 10, and connects the ground circuit 22a and the conductive adhesive layer 51. doing. The slit-shaped via 60c (second upper via) penetrates from the upper surface of the cover coat layer 30 to the lower surface of the cover coat layer 30, and connects the conductive adhesive layer 41 and the ground circuit 22b. The slit-shaped via 60d (second lower via) penetrates from the upper surface of the insulating base material layer 10 to the lower surface of the insulating base material layer 10, and connects the ground circuit 22b and the conductive adhesive layer 51. doing.

  The slit-shaped via 60a and the slit-shaped via 60b are arranged along the ground circuit 22a. The slit-shaped via 60c and the slit-shaped via 60d are arranged along the ground circuit 22b. Other configurations are the same as those in the second embodiment.

Next, a method for manufacturing a flexible printed wiring board according to Embodiment 3 will be described.
FIG. 9 is a process end view illustrating the method for manufacturing a flexible printed wiring board according to the third embodiment. First, similarly to the above-described first embodiment, the steps shown in FIGS. 3A to 3C are performed. Explanation of these steps is omitted.

  Next, as shown in FIG. 9, rectangular holes 61a and 61c that penetrate through the cover coat layer 30 and reach the upper surfaces of the ground circuits 22a and 22b are formed. Rectangular holes 61a and 61c are formed in the X-axis direction along the ground circuits 22a and 22b, respectively. In addition, rectangular holes 61b and 61d that penetrate the insulating base material layer 10 and reach the lower surfaces of the ground circuits 22a and 22b are formed. Rectangular holes 61b and 61d are formed in the X-axis direction along the ground circuits 22a and 22b, respectively.

  Next, the surface of the electromagnetic wave shield sheet 40 on which the conductive adhesive is formed is attached to the upper surface of the cover coat layer 30. On the other hand, the surface of the electromagnetic shielding sheet 50 on which the conductive adhesive is formed is attached to the lower surface of the insulating base material layer 10 with the surface facing upward.

  Next, the rectangular holes 61a and 61c are filled with the conductive adhesive of the electromagnetic wave shielding sheet 40 by hot pressing. At the same time, the conductive adhesive of the electromagnetic wave shielding sheet 50 is filled in the rectangular holes 61b and 61d. Thereafter, the conductive adhesive is cured. As a result, as shown in FIG. 8, the conductive adhesive in the rectangular holes 61a, 61b, 61c and 61d is cured to form slit-like vias 60a, 60b, 60c and 60d. In addition, the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 is solidified to become conductive adhesive layers 41 and 51. In this way, the flexible printed wiring board 3 shown in FIG. 8 is manufactured.

  According to the flexible printed wiring board 3 according to the third embodiment, the slit-shaped via 60 is formed without penetrating the ground circuits 22a and 22b. In this form, the connection reliability of conduction of the conductive adhesive to the ground circuit 22 is further improved. Other effects are the same as those of the first and second embodiments.

  Of the slit-shaped vias 60a to 60d, the upper slit-shaped via or the lower slit-shaped via, for example, the slit-shaped via 60a (first upper via) and the slit-shaped via 60c (second upper upper). The via) is formed by curing the conductive adhesive, and the slit-shaped via 60b (first lower via) and the slit-shaped via 60d (second lower via) are plated with rectangular holes. It is good also as what was formed by. In this case, after the step shown in FIG. 9, the step shown in FIG. 22B is performed inside the rectangular holes 61b and 61d. The slit-shaped via 60a (first upper via) and the slit-shaped via 60c (second upper via) are formed by plating rectangular holes, and the slit-shaped via 60b (first lower via) is formed. Vias) and slit-like vias 60d (second lower vias) may be made by curing a conductive adhesive.

(Embodiment 4)
Next, a flexible printed wiring board according to Embodiment 4 will be described.
FIG. 10 is a cross-sectional view illustrating a flexible printed wiring board according to the fourth embodiment. As shown in FIG. 10, the ground circuit 22 of the flexible printed wiring board 4 is provided between the slit-like via 60 and the signal circuit 21.

  The slit-shaped via 60 includes a first slit-shaped via formed along the X-axis direction (one direction) at a position away from the −Y-axis direction side ground circuit 22a to the −Y-axis direction side. A second slit-shaped via formed along the X-axis direction (one direction) is provided at a position away from the + Y-axis direction side ground circuit 22b toward the + Y-axis direction. Therefore, the ground circuit 22a is disposed between the signal circuit 21 and the first slit-shaped via, and the ground circuit 22b is disposed between the signal circuit 21 and the second slit-shaped via. The flexible printed wiring board 4 is a via different from the slit-shaped via 60, and connects at least one of the conductive adhesive layer 41 and the conductive adhesive layer 51 to the ground circuit 22. A via (not shown) is provided. Thereby, the conductive adhesive layer 41 and the conductive adhesive layer 51 are connected to the ground. Other configurations are the same as those in the first embodiment.

  About the manufacturing method of the flexible printed wiring board 4 which concerns on Embodiment 4, it is the same as that of Embodiment 1 except the positions which form the rectangular hole 61 differ. That is, the cover coat layer 30 and the insulating base material layer 10 are moved along the X-axis direction (one direction) at a position where the rectangular hole 61 is separated from the -Y-axis direction ground circuit 22a to the -Y-axis direction side. It is formed so as to penetrate, and penetrates the cover coat layer 30 and the insulating base material layer 10 along the X-axis direction (one direction) at a position away from the + Y-axis direction side ground circuit 22b to the + Y-axis direction side. To be formed.

  According to the flexible printed wiring board 4 according to the present embodiment, since the ground circuit 22 is disposed together with the signal circuit 21 inside the slit-shaped via 60, the influence of radiation noise in the ground circuit 22 is suppressed. be able to. Other effects are the same as those of the first to third embodiments.

(Embodiment 5)
Next, a flexible printed wiring board according to Embodiment 5 will be described.
FIG. 11 is a cross-sectional view illustrating a flexible printed wiring board according to the fifth embodiment. As shown in FIG. 11, the flexible printed wiring board 5 of the fifth embodiment is formed using a double-sided FCCL80 (see FIG. 12), and the electromagnetic wave shielding sheet 50 in the flexible printed wiring board 1 according to the first embodiment. Instead of this, a copper layer 23 is provided. The copper layer 23 is provided on the entire lower surface of the insulating base material layer 10. The slit-shaped via 60 penetrating the insulating base material layer 10 and the cover coat layer 30 connects the conductive adhesive layer 41 (first conductive layer) and the copper layer 23 (second conductive layer). The flexible printed wiring board 5 has at least one via (not shown) that is different from the slit-like via 60 and connects the conductive adhesive layer 41 and the copper layer 23 to the ground circuit 22. Is provided. Thereby, the conductive adhesive layer 41 and the copper layer 23 are connected to the ground. Other configurations are the same as those in the first embodiment.

Next, a method for manufacturing the flexible printed wiring board 5 according to Embodiment 5 will be described.
12A to 12C are process diagrams illustrating a method for manufacturing a flexible printed wiring board according to the fifth embodiment. FIGS. 12A to 12C are cross-sectional views, and FIG. 12D is an end view. As shown in FIG. 12A, first, a double-sided FCCL 80 is prepared. The double-sided FCCL 80 is obtained by providing copper layers 20 and 23 on both sides of the insulating base material layer 10.

  Next, as shown in FIG. 12B, the signal layer 21 and the ground circuit 22 are formed by processing the copper layer 20 in the double-sided FCCL 80. Thus, the signal circuit 21 and the ground circuit 22 having portions extending in one direction are formed on the insulating base material layer 10 (first insulating layer) provided on the copper layer 23 (first conductive layer). To do.

  Next, as shown in FIG. 12C, the cover coat layer 30 is formed on the insulating base material layer 10, the signal circuit 21, and the ground circuit 22. A cover coat layer 30 is formed so as to have a portion covering the signal circuit 21 and the ground circuit 22. When the cover coat layer 30 is formed, an insulating adhesive layer 31 is formed on one surface of the cover lay 32, and a portion that covers the signal circuit 21 and the ground circuit 22 on the surface on which the insulating adhesive layer 31 is formed is formed. The cover lay 32 is pasted so as to have it. In this manner, the cover coat layer 30 is formed on the insulating base material layer 10, the signal circuit 21, and the ground circuit 22.

  Next, as shown in FIG. 12 (d), the signal circuit 21 and the ground circuit 22 penetrate from the upper surface of the cover coat layer 30 to the lower surface of the insulating base material layer 10 and reach the copper layer 23. A rectangular hole 61 is formed. A rectangular hole 61 is formed in the X-axis direction between the ground circuit 22 a and the signal circuit 21 arranged on the −Y-axis direction side of the signal circuit 21, and the + Y-axis of the signal circuit 21. A second rectangular hole formed along the X-axis direction is formed between the ground circuit 22b disposed on the direction side and the signal circuit 21. That is, the signal circuit 21 is formed so as to be disposed between the first rectangular hole and the second rectangular hole. In addition, a first rectangular hole and a second rectangular hole are arranged on both sides of the signal circuit 21.

  Next, the surface of the electromagnetic wave shield sheet 40 on which the conductive adhesive is formed is attached to the upper surface of the cover coat layer 30. Next, the conductive adhesive of the electromagnetic wave shielding sheet 40 is filled in the rectangular holes 61 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheet 40 and the conductive adhesive in the rectangular hole 61 are cured. As a result, as shown in FIG. 11, the conductive adhesive in the rectangular hole 61 is cured to form a slit-like via 60. Further, the conductive adhesive of the electromagnetic wave shielding sheet 40 is cured to become the conductive adhesive layer 41. Thus, the flexible printed wiring board 5 shown in FIG. 11 is manufactured. The flexible printed wiring board 5 preferably forms a cover coat layer on the surface of the copper layer 23.

  According to the flexible printed wiring board 5 according to the present embodiment, since the double-sided FCCL80 is used, the copper layer 23 can be used as a shield. Moreover, since a circuit pattern can be formed in the copper layer 23 as needed, the flexible printed wiring board can be made short and thin. Other effects are the same as those of the first to fourth embodiments.

(Embodiment 6)
Next, a flexible printed wiring board according to Embodiment 6 will be described.
FIG. 13 is a cross-sectional view illustrating a flexible printed wiring board according to the sixth embodiment. As shown in FIG. 13, the flexible printed wiring board 6 according to the present embodiment uses a double-sided FCCL80, and instead of the electromagnetic wave shielding sheet 50 in the flexible printed wiring board 2 according to the second embodiment, a copper layer 23 is used. Is provided. The copper layer 23 is provided on the entire lower surface of the insulating base material layer 10. A slit-like via 60 penetrating the insulating base material layer 10, the ground circuit 22, and the cover coat layer 30 connects the conductive adhesive layer 41 (second conductive layer) and the copper layer 23 (first conductive layer). doing. Other configurations are the same as those of the second embodiment.

Next, a method for manufacturing the flexible printed wiring board 6 according to Embodiment 6 will be described.
First, similarly to the above-described fifth embodiment, the steps shown in FIGS. 12A to 12C are performed. Explanation of these steps is omitted. Next, a rectangular hole 61 that penetrates the cover coat layer 30, the ground circuit 22, and the insulating base material layer 10 and reaches the copper layer 23 is formed. That is, the rectangular hole 61 penetrates the ground circuit 22a and is formed in the X-axis direction (one direction) along the ground circuit 22a. Further, the rectangular hole 61 penetrates the ground circuit 22b and is formed in the X-axis direction (one direction) along the ground circuit 22b.

  Next, the surface of the electromagnetic wave shield sheet 40 on which the conductive adhesive is formed is attached to the upper surface of the cover coat layer 30. Next, the conductive adhesive of the electromagnetic wave shielding sheet 40 is filled in the rectangular holes 61 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheet 40 and the conductive adhesive in the rectangular hole 61 are cured. As a result, the conductive adhesive in the rectangular hole 61 is cured to form the slit-shaped via 60. Further, the conductive adhesive of the electromagnetic wave shielding sheet 40 is cured to become the conductive adhesive layer 41. In this way, the flexible printed wiring board 6 shown in FIG. 13 is manufactured. The effects of the flexible printed wiring board 6 according to the present embodiment are the same as those of the second and fifth embodiments.

(Embodiment 7)
Next, a flexible printed wiring board according to Embodiment 7 will be described.
FIG. 14 is a cross-sectional view illustrating a flexible printed wiring board according to the seventh embodiment. As shown in FIG. 14, the flexible printed wiring board 7 according to the present embodiment uses a double-sided FCCL80, and instead of the electromagnetic wave shielding sheet 50 in the flexible printed wiring board 4 according to the fourth embodiment, a copper layer 23 is used. Is provided. The copper layer 23 is provided on the entire lower surface of the insulating base material layer 10. The ground circuit 22 of the flexible printed wiring board 7 is provided between the slit-like via 60 and the signal circuit 21. The slit-shaped via 60 penetrating the insulating base material layer 10 and the cover coat layer 30 connects the conductive adhesive layer 41 (second conductive layer) and the copper layer 23 (first conductive layer). The flexible printed wiring board 7 is a via different from the slit-shaped via 60 and connects at least one slit (not shown) that connects the conductive adhesive layer 41 and the copper layer 23 to the ground circuit 22. Shaped vias are provided. Thereby, the conductive adhesive layer 41 and the copper layer 23 are connected to the ground. Other configurations are the same as those in the fourth embodiment.

Next, a method for manufacturing the flexible printed wiring board 7 according to Embodiment 7 will be described.
First, similarly to the above-described fifth embodiment, the steps shown in FIGS. 12A to 12C are performed. Explanation of these steps is omitted. Next, from the upper surface of the cover coat layer 30 to the lower surface of the insulating base material layer 10 along the X-axis direction (one direction) at a position away from the −Y-axis direction side ground circuit 22a on the −Y-axis direction side From the upper surface of the cover coat layer 30 along the X-axis direction (one direction) at a position away from the + Y-axis direction side from the rectangular hole 61 penetrating and reaching the copper layer 23 and the ground circuit 22b on the + Y-axis direction side A rectangular hole 61 that penetrates to the lower surface of the insulating base material layer 10 and reaches the copper layer 23 is formed.

  Next, the surface of the electromagnetic wave shield sheet 40 on which the conductive adhesive is formed is attached to the upper surface of the cover coat layer 30. Next, the conductive adhesive of the electromagnetic wave shielding sheet 40 is filled in the rectangular holes 61 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheet 40 and the conductive adhesive in the rectangular hole 61 are cured. As a result, the conductive adhesive in the rectangular hole 61 is cured to form the slit-shaped via 60. Further, the conductive adhesive of the electromagnetic wave shielding sheet 40 is cured to become the conductive adhesive layer 41. In this way, the flexible printed wiring board 7 shown in FIG. 14 is manufactured. The effects of the flexible printed wiring board 7 according to the present embodiment are the same as those of the fourth and fifth embodiments.

(Embodiment 8)
Next, the flexible printed wiring board 8 according to Embodiment 8 will be described.
FIG. 15 is a cross-sectional view illustrating a flexible printed wiring board according to the eighth embodiment. As shown in FIG. 15, the flexible printed wiring board 8 according to the present embodiment uses a double-sided FCCL80, and a signal circuit 21 and a ground circuit 22 are provided on one side 11 of the double-sided FCCL80, A signal circuit 21 and a ground circuit 22 are also provided on the other surface 12 opposite to the surface 11. The signal circuit 21 on the other surface 12 is located below the signal circuit 21 on the one surface 11, and the ground circuit 22 on the other surface 12 is located below the ground circuit 22 on the one surface 11. Yes.
And also on the other surface 12 side, the insulating adhesive layer 31, the cover lay 32, the conductive adhesive layer 51, and the insulating layer 52 are arranged in the order closer to the insulating base material layer 10, similarly to the one surface 11 side. Are stacked. The insulating adhesive layer 31 and the cover lay 32 constitute a cover coat layer 30, and the conductive adhesive layer 51 and the insulating layer 52 constitute an electromagnetic wave shield sheet 50.

  The slit-shaped via 60 is provided in a rectangular hole 61 penetrating the cover coat layer 30 on the one surface 11 side, the insulating base material layer 10 and the cover coat layer 30 on the other surface 12 side. The slit-shaped via 60 connects the conductive adhesive layer 41 and the conductive adhesive layer 51.

  The slit-shaped via 60 is a first slit shape formed along the X-axis direction (one direction) between the signal circuit 21 and the ground circuit 22 a disposed on the −Y-axis direction side of the signal circuit 21. And a second slit-shaped via formed along the X-axis direction (one direction) between the signal circuit 21 and the ground circuit 22b disposed on the + Y-axis direction side of the signal circuit 21. Have. The signal circuit 21 is disposed between the first slit-shaped via 60 and the second slit-shaped via 60. The first slit-shaped via 60 is disposed between the signal circuit 21 and the ground circuit 22a, and the second slit-shaped via 60 is disposed between the signal circuit 21 and the ground circuit 22b. . The flexible printed wiring board 8 is a via different from the slit-shaped via 60, and connects at least one of the conductive adhesive layer 41 and the conductive adhesive layer 51 to the ground circuit 22. A via (not shown) is provided. Thereby, the conductive adhesive layers 41 and 51 are connected to the ground. Other configurations are the same as those in the first and fifth embodiments.

Next, a method for manufacturing the flexible printed wiring board 8 according to Embodiment 8 will be described.
FIG. 16 is a process diagram illustrating a method for manufacturing a flexible printed wiring board according to Embodiment 8, wherein (a) to (c) are cross-sectional views, and (d) is an end view. As shown in FIG. 16A, first, a double-sided FCCL 80 is prepared. The double-sided FCCL 80 has a copper layer 20 provided on one surface 11 of the insulating base material layer 10 and a copper layer 23 provided on the other surface 12.

  Next, as shown in FIG. 16B, the signal layer 21 and the ground circuit 22 are formed by processing the copper layer 20 in the double-sided FCCL 80. Further, the signal layer 21 and the ground circuit 22 are formed by processing the copper layer 23.

  Next, as shown in FIG. 16C, the cover coat layer 30 is formed on the signal circuit 21 and the ground circuit 22 on the one surface 11 side of the insulating base material layer 10. Further, a cover coat layer 30 is formed below the signal circuit 21 and the ground circuit 22 on the other surface 12 side. The cover coat layer 30 is formed so as to have portions covering the signal circuit 21 and the ground circuit 22 on both sides. When the cover coat layer 30 is formed, an insulating adhesive layer 31 is formed on one surface of the cover lay 32, and a portion that covers the signal circuit 21 and the ground circuit 22 on the surface on which the insulating adhesive layer 31 is formed is formed. The cover lay 32 is pasted so as to have it. In the case of forming the cover coat layer 30, the cover coat layer 30 may be formed from one surface 11 side, or the cover coat layer 30 may be formed from the other surface 12 side. You may form simultaneously.

  Next, as shown in FIG. 16D, between the signal circuit 21 and the ground circuit 22, the cover coat layer 30 on the one surface 11 side, the insulating base material layer 10, and the cover on the other surface 12 side. A rectangular hole 61 penetrating the coat layer 30 is formed. The rectangular hole 61 includes a first rectangular hole formed along the X-axis direction between the ground circuit 22 a arranged on the −Y-axis direction side of the signal circuit 21 and the signal circuit 21, and + Y of the signal circuit 21. A second rectangular hole is formed between the ground circuit 22b arranged on the axial direction side and the signal circuit 21 along the X-axis direction. That is, the rectangular hole 61 is formed so that the signal circuit 21 is disposed between the first rectangular hole and the second rectangular hole. In addition, a first rectangular hole and a second rectangular hole are arranged on both sides of the signal circuit 21.

  Next, the surface of the electromagnetic wave shielding sheet 40 on which the conductive adhesive is formed is attached to the upper surface of the cover coat layer 30 on the one surface 11 side. Further, the surface of the electromagnetic wave shielding sheet 50 on which the conductive adhesive is formed is attached to the lower surface of the cover coat layer 30 on the other surface 12 side. Next, the rectangular adhesive holes 61 are filled with the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 and the conductive adhesive in the rectangular hole 61 are cured. As a result, as shown in FIG. 15, the conductive adhesive in the rectangular hole 61 is cured to form a slit-like via 60. Further, the conductive adhesives of the electromagnetic wave shielding sheets 40 and 50 are cured to become conductive adhesive layers 41 and 51. In this way, the flexible printed wiring board 8 shown in FIG. 15 is manufactured.

  According to this embodiment, the signal circuit 21 and the ground circuit can be provided also on the other surface 12 side of the insulating base material layer 10. Thereby, the integration degree of the flexible printed wiring board 8 can be improved. Other effects are the same as those of the first and fifth embodiments.

(Embodiment 9)
Next, the flexible printed wiring board 9 according to Embodiment 9 will be described.
FIG. 17 is a cross-sectional view illustrating a flexible printed wiring board 9 according to the ninth embodiment. As shown in FIG. 17, the flexible printed wiring board 9 uses a double-sided FCCL 80, and the position of the slit-shaped via 60 is different from the flexible printed wiring board 8 shown in FIG.

  In the flexible printed wiring board 9, the slit-shaped via 60 includes a cover coat layer 30 on one surface 11 side, a ground circuit 22 on one surface 11 side, an insulating base material layer 10, and a ground circuit on the other surface 12 side. 22 and the rectangular hole 61 penetrating the cover coat layer 30 on the other surface 12 side. The slit-shaped via 60 connects the conductive adhesive layer 41 and the conductive adhesive layer 51.

  The slit-shaped via 60 is provided in the X-axis direction along the ground circuit 22 on the one surface 11 side and the other surface 12 side. That is, the slit-shaped via 60 passes through the ground circuit 22a on the one surface 11 side and the other surface 12 side, and is a first slit formed in the X-axis direction (one direction) along the ground circuit 22a. And the second slit-shaped via formed in the X-axis direction (one direction) along the ground circuit 22b through the ground circuit 22b on the one surface 11 side and the other surface 12 side. Have. Other configurations are the same as those in the second, sixth, and eighth embodiments.

  Next, a method for manufacturing the flexible printed wiring board 9 according to Embodiment 9 will be described. First, similarly to the above-described eighth embodiment, the steps shown in FIGS. 16A to 16C are performed. Explanation of these steps is omitted. Next, the cover coat layer 30 on the one surface 11 side, the ground circuit 22 on the one surface 11 side, the insulating base material layer 10, the ground circuit 22 on the other surface 12 side, and the cover coat layer on the other surface 12 side A rectangular hole 61 passing through 30 is formed. That is, the rectangular hole 61 also penetrates the ground circuit 22a on the one surface 11 side and the other surface 12 side, and is formed in the X-axis direction (one direction) along the ground circuit 22a. The rectangular hole 61 also penetrates the ground circuit 22b on the one surface 11 side and the other surface 12 side, and is formed in the X-axis direction (one direction) along the ground circuit 22b.

  Next, the surface of the electromagnetic wave shielding sheet 40 on which the conductive adhesive is formed is attached to the upper surface of the cover coat layer 30 on the one surface 11 side. Further, the surface of the electromagnetic wave shielding sheet 50 on which the conductive adhesive is formed is attached to the lower surface of the cover coat layer 30 on the other surface 12 side. Next, the rectangular adhesive holes 61 are filled with the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 and the conductive adhesive in the rectangular hole 61 are cured. Thereby, as shown in FIG. 17, the conductive adhesive in the rectangular hole 61 is cured to form a slit-like via 60. Further, the conductive adhesives of the electromagnetic wave shielding sheets 40 and 50 are cured to become conductive adhesive layers 41 and 51. In this way, the flexible printed wiring board 9 shown in FIG. 17 is manufactured. The effects of the flexible printed wiring board 9 according to the present embodiment are the same as those of the second, sixth, and eighth embodiments.

(Embodiment 10)
Next, the flexible printed wiring board 9a according to Embodiment 10 will be described.
FIG. 18 is a cross-sectional view illustrating a flexible printed wiring board according to the tenth embodiment. As shown in FIG. 18, the flexible printed wiring board 9a according to the present embodiment uses a double-sided FCCL80, and the position of the slit-like via 60 is different from that of the flexible printed wiring board 8 shown in FIG. Yes.

  In the flexible printed wiring board 9a, the slit-shaped via 60 is formed in the rectangular hole 61 penetrating the cover coat layer 30 on the one surface 11 side, the insulating base material layer 10, and the cover coat layer 30 on the other surface 12 side. Is provided. The slit-shaped via 60 connects the conductive adhesive layer 41 and the conductive adhesive layer 51.

  The slit-shaped via 60 includes a first slit-shaped via formed along the X-axis direction (one direction) at a position away from the −Y-axis direction side ground circuit 22a to the −Y-axis direction side. A second slit-shaped via formed along the X-axis direction (one direction) is provided at a position away from the + Y-axis direction side ground circuit 22b toward the + Y-axis direction. Therefore, the ground circuit 22a is disposed between the signal circuit 21 and the first slit-shaped via, and the ground circuit 22b is disposed between the signal circuit 21 and the second slit-shaped via. The flexible printed wiring board 9 a is a via different from the slit-shaped via 60, and connects at least one of the conductive adhesive layer 41 and the conductive adhesive layer 51 to the ground circuit 22. A via (not shown) is provided. Thereby, the conductive adhesive layer 41 and the conductive adhesive layer 51 are connected to the ground. Other configurations are the same as those in the fourth, seventh, and eighth embodiments.

  The manufacturing method of the flexible printed wiring board 9a according to the tenth embodiment is the same as that of the eighth embodiment except that the positions where the rectangular holes 61 are formed are different. Specifically, the cover coat layer 30 on the one surface 11 side is disposed along the X-axis direction (one direction) at a position where the rectangular hole 61 is separated from the −Y-axis direction side ground circuit 22a to the −Y-axis direction side. It is formed so as to penetrate the insulating base material layer 10 and the cover coat layer 30 on the other surface 12 side, and at the position away from the + Y-axis direction side ground circuit 22b toward the + Y-axis direction side in the X-axis direction (one The cover coat layer 30 on the one surface 11 side, the insulating base material layer 10, and the cover coat layer 30 on the other surface 12 side are formed so as to penetrate along the direction). The effect of this embodiment is the same as that of Embodiments 4, 7, and 8.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, you may apply the electromagnetic wave shield sheet 40a which concerns on the modification of Embodiment 1 to flexible printed wiring boards 2-10 other than the flexible printed wiring board 1 which concerns on Embodiment 1. FIG. Further, based on the simulation result, the opposing interval between the first slit-like via 60 and the second slit-like via 60 formed in accordance with the wavelength of the signal transmitted through the signal circuit 21 and the slits. The thickness of the vias can be determined to an optimum value.

  Moreover, the electronic device to which the flexible printed wiring board of the present invention is connected can effectively suppress high-frequency noise radiated from the flexible printed wiring board and simultaneously shield external high-frequency noise.

1, 1a, 2, 3, 4, 5, 6, 7, 8, 9a Flexible printed wiring board 10 Insulating base material layer 11 Surface 20 Circuit pattern 23 Copper layer 21 Signal circuit 22, 22a, 22b Ground circuit 30 Cover coat Layer 31 Insulating adhesive layer 32 Coverlay 40, 40a, 50, 50a Electromagnetic wave shield sheet 41, 51 Conductive adhesive layer 42, 52 Insulating layer 43, 53 Metal layers 60, 60a, 60b, 60c, 60d Slit shape Via 61, 61a, 61b, 61c, 61d Rectangular hole 70 Single-sided FCCL
80 Double-sided FCCL
90 Radiation noise 101, 102 Flexible printed wiring board 110 Insulating layer 120, 123, 124 Copper layer 121 Signal circuit 122 Ground circuit 130 Insulating layer 131, 134 Insulating adhesive layer 132, 135 Coverlay 140, 150 Shield sheets 141, 151 Conductive layers 142 and 152 Insulating layers 143 and 153 Copper foil layer 160 Via 161 Through hole 162 Plating layer 170 Single-sided FCCL
180 double sided FCCL

Claims (12)

A first conductive layer;
A first insulating layer provided on the first conductive layer;
A signal circuit having a portion provided on the first insulating layer and extending in one direction;
A second insulating layer provided on the first insulating layer and the signal circuit;
A second conductive layer provided on the second insulating layer;
A conductive slit-shaped via that penetrates from the upper surface of the second insulating layer to the lower surface of the first insulating layer, and connects the second conductive layer and the first conductive layer;
With
The slit-shaped via has a first slit-shaped via and a second slit-shaped via formed along the signal circuit with the signal circuit interposed therebetween, and the signal circuit includes the first slit. A flexible printed wiring board disposed between the via and the second slit-like via. A first ground circuit and a second ground circuit each having a portion provided on the first insulating layer and extending in the one direction;
The second insulating layer is provided on the first ground circuit and the second ground circuit,
The signal circuit is disposed between the first ground circuit and the second ground circuit,
The first slit-shaped via is disposed between the signal circuit and the first ground circuit,
The flexible printed wiring board according to claim 1, wherein the second slit-shaped via is disposed between the signal circuit and the second ground circuit. A first ground circuit and a second ground circuit each having a portion provided on the first insulating layer and extending in the one direction;
The second insulating layer is provided on the first ground circuit and the second ground circuit,
The signal circuit is disposed between the first ground circuit and the second ground circuit,
The first slit-shaped via also penetrates the first ground circuit and is disposed along the first ground circuit;
The flexible printed wiring board according to claim 1, wherein the second slit-shaped via penetrates the second ground circuit and is disposed along the second ground circuit. A first ground circuit and a second ground circuit each having a portion provided on the first insulating layer and extending in the one direction;
The second insulating layer is provided on the first ground circuit and the second ground circuit,
The signal circuit is disposed between the first ground circuit and the second ground circuit,
The first ground circuit is disposed between the signal circuit and the first slit-shaped via,
The flexible printed wiring board according to claim 1, wherein the second ground circuit is disposed between the signal circuit and the second slit-shaped via. A first conductive layer;
A first insulating layer provided on the first conductive layer;
A first ground circuit and a second ground circuit each having a portion provided on the first insulating layer and extending in one direction;
A signal circuit provided on the first insulating layer and having a portion extending in the one direction and disposed between the first ground circuit and the second ground circuit;
A second insulating layer provided on the first insulating layer, the signal circuit, the first ground circuit, and the second ground circuit;
A second conductive layer provided on the second insulating layer;
A conductive first upper slit-like via that penetrates from the upper surface of the second insulating layer to the lower surface of the second insulating layer, and connects the second conductive layer and the first ground circuit;
A conductive first lower slit-shaped via that penetrates from the upper surface of the first insulating layer to the lower surface of the first insulating layer and connects the first ground circuit and the first conductive layer;
A conductive second upper slit-shaped via that penetrates from the upper surface of the second insulating layer to the lower surface of the second insulating layer and connects the second conductive layer and the second ground circuit;
A conductive second lower slit-shaped via that penetrates from the upper surface of the first insulating layer to the lower surface of the first insulating layer and connects the second ground circuit and the first conductive layer;
With
The first upper slit-like via and the first lower slit-like via are arranged side by side along the first ground circuit,
The flexible printed wiring board in which the second upper slit-shaped via and the second lower slit-shaped via are arranged side by side along the second ground circuit. A first conductive layer;
A first insulating layer provided on the first conductive layer;
A first ground circuit and a second ground circuit each having a portion provided on the first insulating layer and extending in one direction;
A signal circuit provided on the first insulating layer and having a portion extending in the one direction and disposed between the first ground circuit and the second ground circuit;
A second insulating layer provided on the first insulating layer, the signal circuit, the first ground circuit, and the second ground circuit;
A second conductive layer provided on the second insulating layer;
A conductive slit-shaped via that penetrates from the upper surface of the second insulating layer to the lower surface of the first insulating layer, and connects the second conductive layer and the first conductive layer;
With
The slit-shaped via has a first slit-shaped via and a second slit-shaped via formed along the signal circuit on both outer sides of the signal circuit;
The first slit-shaped via is disposed between the signal circuit and the first ground circuit,
The second slit-shaped via is a flexible printed wiring board disposed between the signal circuit and the second ground circuit.   The flexible printed wiring board according to any one of claims 1 to 6, wherein the slit-shaped via is formed by curing a conductive adhesive of an electromagnetic wave shielding sheet. A third insulating layer provided on the second conductive layer;
The electromagnetic wave shielding sheet includes the second conductive layer and the third insulating layer,
The flexible printed wiring board according to claim 7, wherein the second conductive layer is obtained by curing the conductive adhesive of the electromagnetic wave shielding sheet. A metal layer provided on the second conductive layer;
A third insulating layer provided on the metal layer;
Further comprising
The electromagnetic wave shielding sheet includes the second conductive layer, the metal layer, and the third insulating layer,
The flexible printed wiring board according to claim 7, wherein the second conductive layer is obtained by curing the conductive adhesive of the electromagnetic wave shielding sheet. Forming a signal circuit having a portion extending in one direction on the first insulating layer;
Forming a second insulating layer on the first insulating layer and the signal circuit;
Forming a rectangular hole penetrating from the upper surface of the second insulating layer to the lower surface of the first insulating layer along the signal circuit across the signal circuit;
With
Attaching the surface of the electromagnetic shielding sheet on which the conductive adhesive is formed on the upper surface of the second insulating layer;
Attaching the surface of the electromagnetic shielding sheet on which the conductive adhesive is formed to the lower surface of the first insulating layer;
Filling the rectangular hole with the conductive adhesive of the electromagnetic wave shielding sheet by hot pressing,
Curing the conductive adhesive of the electromagnetic wave shielding sheet and the conductive adhesive in the rectangular hole;
A method for producing a flexible printed wiring board, further comprising: Forming a signal circuit having a portion extending in one direction on a first insulating layer provided on the first conductive layer;
Forming a second insulating layer on the first insulating layer and the signal circuit;
Forming a rectangular hole penetrating from the upper surface of the second insulating layer to the lower surface of the first insulating layer along the signal circuit across the signal circuit, and reaching the first conductive layer;
Attaching the surface of the electromagnetic shielding sheet on which the conductive adhesive is formed on the upper surface of the second insulating layer;
Filling the rectangular hole with the conductive adhesive of the electromagnetic wave shielding sheet by hot pressing,
Curing the conductive adhesive of the electromagnetic wave shielding sheet and the conductive adhesive in the rectangular hole;
A method for producing a flexible printed wiring board, further comprising:   The electronic device to which the flexible printed wiring board as described in any one of the said Claims 1-9 was connected.