JP2017152562A - Flexible printed wiring board, method for manufacturing flexible printed wiring board and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible printed wiring board in which radiation noises can be suppressed and flexibility can be improved, a method for manufacturing a flexible printed wiring board, and an electronic apparatus.SOLUTION: The flexible printed wiring board of the present invention includes a conductive adhesive layer 51, an insulating base layer 10 disposed on the conductive adhesive layer 51, a signal circuit 21 disposed on the insulating base layer 10 and having a portion extending in one direction, a cover coat layer 30 disposed on the insulating base layer 10 and the signal circuit 21, a conductive adhesive layer 41 disposed on the cover coat layer 30, and a plurality of conductive via holes 60 penetrating from an upper surface of the cover coat layer 30 to a lower surface of the insulating base layer 10 and connecting the conductive adhesive layer 41 to the conductive adhesive layer 51. An interval Y of the via holes 60 and a wavelength X of signals transmitted in the signal circuit 21 satisfy Y≤0.16 X-1.17.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. 23 and 24, 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. 25 and 26, the conventional method of manufacturing the flexible printed wiring board 102 is as follows. First, a double-sided flexible copper-clad laminate in which a copper layer 120 is formed on the upper surface of the insulating layer 110 and a copper layer 123 is formed on the lower surface. (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. 25B). 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. 25C). . Next, the copper layer 124 is laminated on the cover lay 132 (FIG. 25D).

  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. 26A). 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. 26B).

  And the coverlay 135 is formed through the insulating adhesive layer 134 so that it may be pinched | interposed from the upper and lower sides (FIG.26 (c)). 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 plurality of conductive vias that penetrate to the lower surface of the layer and connect the second conductive layer and the first conductive layer, and the plurality of vias are arranged at intervals along the one direction. A first via row and a second via row spaced apart along the one direction, wherein the signal circuit includes the first via row, the second via row, and the second via row. A signal transmitted through the signal circuit is defined as Y between the vias arranged adjacent to each other in the one direction. When the wavelength of the signal is X, the following formula (1),
<Equation 1> Y ≦ 0.16 · X−1.17 (1)
It satisfies.

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 plurality of through holes penetrating from the upper surface of the second insulating layer to the lower surface of the first insulating layer, the plurality of through holes extending along the one direction. Forming a plurality of rows of first through holes arranged at intervals and a row of second through holes arranged at intervals along the one direction, wherein the plurality of through holes are formed as described above. The signal circuit is formed so as to be disposed between the first through-hole row and the second through-hole row, and an interval between the adjacent through-holes in the one direction is Y, Wavelength of signal transmitted through signal circuit When X is X, the following equation (2),
<Equation 2> Y ≦ 0.16 · X−1.17 (2)
And attaching the surface of the electromagnetic shielding sheet on which the conductive adhesive is formed on the upper surface of the second insulating layer to the lower surface of the first insulating layer. A step of attaching the surface of the electromagnetic shielding sheet on which the conductive adhesive is formed, and a step of attaching the conductive adhesive of the electromagnetic shielding sheet in the through hole by hot pressing. And a step of curing the conductive adhesive of the electromagnetic wave shielding sheet and the conductive adhesive in the through hole.

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

  ADVANTAGE OF THE INVENTION According to this invention, even when a high frequency signal is sent, radiation noise can be suppressed, the flexibility can be improved, and the manufacturing cost can be reduced. Equipment can be provided.

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. In the flexible printed wiring board in which the via 60 is disposed between the signal circuit 21 and the ground circuit 22, the radiation noise leaking from the via gap is simulated when the frequency of the signal transmitted to the signal circuit is 1 [GHz]. (A) is a via interval of 47 [mm], (b) is a via interval of 7 [mm], and (c) is a via interval of 3 [mm]. (D) is a via interval of 1 [mm]. In the flexible printed wiring board in which the via 60 is arranged between the signal circuit 21 and the ground circuit 22, the radiation noise leaking from the via gap is simulated when the frequency of the signal transmitted to the signal circuit is 10 [GHz]. (A) is a via interval of 47 [mm], (b) is a via interval of 7 [mm], and (c) is a via interval of 3 [mm]. (D) is a via interval of 1 [mm]. (A) The frequency of the signal transmitted to the signal circuit is 1 [GHz], 5 [GHz], 10 [GHz] and 20 [GHz], and the via interval is 47 [mm], 7 [mm], 3 It is the figure which illustrated the simulation result of the radiation noise which leaks from the gap of a via in the case of [mm] and 1 [mm], and (b) is the figure which illustrated the necessary via interval calculated from the simulation result is there. (A) is the graph which illustrated the relationship between the frequency of the signal transmitted to a signal circuit, and the via | veer space | interval required in order to suppress the influence of radiation noise, a horizontal axis shows a frequency and a vertical axis | shaft is (B) is a graph illustrating the relationship between the wavelength of the signal transmitted to the signal circuit and the via interval necessary for suppressing the influence of radiation noise, and the horizontal axis indicates the wavelength. The vertical axis indicates the via interval. 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. A shield sheet 40, an electromagnetic wave shield sheet 50, and a plurality of vias 60 are provided. In FIG. 2, the 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 a high-frequency signal. 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 in vias 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 via 60 is provided in the through 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 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 via 60 connects the conductive adhesive layer 41 and the conductive adhesive layer 51. A plurality of through holes 61 are provided, and a plurality of vias 60 are also provided. The plurality of vias 60 are arranged in rows (spaces) arranged at intervals 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. 1 via) and the signal circuit 21 between the ground circuit 22b arranged on the + Y-axis direction side and the signal circuit 21 and arranged at intervals along the X-axis direction (one direction) ( Second via row). The signal circuit 21 is disposed between the first via 60 column and the second via 60 column. The first via 60 column is disposed between the signal circuit 21 and the ground circuit 22a, and the second via column is disposed between the signal circuit 21 and the ground circuit 22b. An interval between vias 60 adjacent in the X-axis direction is referred to as an interval between vias 60 or a via interval.

  Further, a via is formed between a line connecting vias 60 arranged in the X axis direction on the −Y axis side of the signal circuit 21 and a line connecting vias 60 arranged in the X axis direction on the + Y axis side of the signal circuit 21. It is called the inside surrounded by 60. On the other hand, the vias 60 arranged in the X-axis direction on the −Y-axis direction side and the + Y-axis side of the signal circuit 21 from the line connecting the vias 60 arranged in the X-axis direction on the −Y-axis side of the signal circuit 21 are connected. The + Y axis direction side from the line is referred to as the outside of the via 60.

  The 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 via 60 is in contact with the conductive adhesive layer 51. The via 60 is obtained by curing the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50. Therefore, the via 60 includes the same material as the conductive adhesive layer 41 and the conductive adhesive layer 51. Therefore, the via 60 is conductive. Note that the flexible printed wiring board 1 is a via different from the via 60 and connects the conductive adhesive layer 41 and the conductive adhesive layer 51 and at least one via (not shown) connected to the ground circuit 22. 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 is a circuit pattern 20 formed 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 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 plurality of through holes 61 penetrating from the upper surface of the cover coat layer 30 to the lower surface of the insulating base material layer 10 are formed. A plurality of through-holes 61 arranged in a row along the X-axis direction (first through-holes) 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 row (second through-hole row) lined up along the X-axis direction between the signal circuit 21 and the ground circuit 22b arranged on the + Y-axis direction side of the signal circuit 21 and the signal circuit 21. It forms so that it becomes. That is, the plurality of through holes 61 are formed so that the signal circuit 21 is disposed between the first through hole column and the second through hole column. Thus, the first through-hole columns and the second through-hole columns 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 conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 is filled into the through holes 61 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 and the conductive adhesive in the through 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 to fill each other and cure after being cured. 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.

  Thereby, as shown in FIG.1 and FIG.2, the via | veer 60 is formed and the flexible printed wiring board 1 shown in FIG.1 and FIG.2 is manufactured.

  According to the present embodiment, the signal circuit 21 is sandwiched between the conductive vias 60. The via 60 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. 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. Therefore, it is possible to suppress the radiation noise from the signal circuit 21 from leaking from the inside surrounded by the via 60 to the outside of the via 60. Therefore, the shielding of electromagnetic waves can be improved.

  Moreover, since the via 60 is formed of a conductive adhesive, flexibility can be improved. Furthermore, since the via 60 can be formed by hot pressing the electromagnetic wave shielding sheet as described above, the 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 1a 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 40 a of the modified example, the electromagnetic wave shielding sheet 40 is provided on the conductive adhesive layer 41 instead of the laminated structure of the insulating layer 42 and the conductive adhesive layer 41. The laminated structure includes the metal layer 43 formed and the insulating layer 42 provided on the metal layer 43. Further, in the electromagnetic wave shielding sheet 50a (not shown), instead of a laminated structure of the insulating layer 52 and the conductive adhesive layer 51, a metal layer 53 provided below the conductive adhesive layer 51, and a lower part of the metal layer 53 A laminated structure including an insulating layer 42 provided on the substrate. Thereby, the electromagnetic wave shielding property at the time of flowing a high frequency signal can be improved more. In the flexible printed wiring board 1a, the electromagnetic wave shielding sheet 40a includes a conductive adhesive layer 41, an insulating layer 42, and a metal layer 43. When the electromagnetic shielding sheet 40a is used alone as a member of the flexible printed wiring board 1a, the conductive adhesive is used. And an insulating layer 42 and a metal layer 43. Further, the electromagnetic wave shielding sheet 50a includes a conductive adhesive layer 51, an insulating layer 52, and a metal layer 53 in the flexible printed wiring board 1a, and is electrically conductive before it becomes a member of the flexible printed wiring board 1a. An adhesive, an insulating layer 52 and a metal layer 53 are included.

  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 via 60 is provided in a through hole 61 that penetrates the cover coat layer 30, the ground circuit 22, and the insulating base material layer 10. The plurality of vias 60 are provided along the ground circuit 22 and spaced apart in the X-axis direction. That is, the plurality of vias 60 also penetrates the ground circuit 22a, and is arranged along the ground circuit 22a with a space in the X-axis direction (one direction) (first via row) and the ground circuit 22b. And a row (second via row) arranged along the ground circuit 22b with an interval in the X-axis direction (one direction). 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, a plurality of through holes 61 penetrating the cover coat layer 30, the ground circuit 22, and the insulating base material layer 10 are formed. That is, the plurality of through holes 61 are formed so as to penetrate the ground circuit 22a and to be arranged at intervals along the X-axis direction (one direction) along the ground circuit 22a. The plurality of through holes 61 are also formed so as to penetrate the ground circuit 22b and to be arranged along the ground circuit 22b with an interval in the X-axis direction (one direction).

  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 conductive adhesive in the electromagnetic wave shielding sheets 40 and 50 is filled in the through holes 61 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 and the conductive adhesive in the through hole 61 are cured. The conditions for hot pressing are the same as those in the first embodiment. Thereby, the via 60 is formed as shown in FIGS. 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 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 through hole 61 does not penetrate the ground circuit 22 and is formed 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 to the lower surface of the insulating base material layer 10. It has been done.

  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 through hole does not penetrate the ground circuit 22. The through hole 61a penetrates from the upper surface of the cover coat layer 30 to the upper surface of the ground circuit 22a. The through hole 61b penetrates from the lower surface of the ground circuit 22a to the lower surface of the insulating base material layer 10. The through hole 61c penetrates from the upper surface of the cover coat layer 30 to the upper surface of the ground circuit 22b. The through hole 61d penetrates from the lower surface of the ground circuit 22b to the lower surface of the insulating base material layer 10.

  The 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 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. . The 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 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. .

  The plurality of vias 60a and the plurality of vias 60b are arranged side by side along the ground circuit 22a at intervals. The plurality of vias 60c and the plurality of vias 60d are arranged side by side along the ground circuit 22b at intervals. 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, through 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. A plurality of through holes 61a and 61c are formed along the ground circuits 22a and 22b so as to be arranged at intervals in the X-axis direction. In addition, through 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. A plurality of through holes 61b and 61d are formed along the ground circuits 22a and 22b so as to be arranged at intervals in the X-axis direction.

  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 conductive adhesive of the electromagnetic wave shielding sheet 40 is filled in the through holes 61a and 61c by hot pressing. At the same time, the conductive adhesive of the electromagnetic wave shielding sheet 50 is filled in the through holes 61b and 61d. Thereafter, the conductive adhesive is cured. As a result, as shown in FIG. 8, the conductive adhesive in the through holes 61a, 61b, 61c and 61d is cured to form 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 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 vias 60a to 60d, the upper via or the lower via, for example, the via 60a (first upper via) and the via 60c (second upper via) are obtained by curing the conductive adhesive. Yes, the via 60b (first lower via) and the via 60d (second lower via) may be formed by plating a through hole. In this case, after the step shown in FIG. 9, the step shown in FIG. 26B is performed inside the through holes 61b and 61d. The via 60a (first upper via) and the via 60c (second upper via) are formed by plating through holes, and the via 60b (first lower via) and via 60d (second lower via) are formed. The vias may be hardened with 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 via 60 and the signal circuit 21.

  The plurality of vias 60 are arranged at intervals in the X-axis direction (one direction) at positions away from the −Y-axis direction side ground circuit 22a in the −Y-axis direction side (the first vias). Row) and a row (second via row) arranged at intervals along the X-axis direction (one direction) at a position away from the + Y-axis direction side ground circuit 22b on the + Y-axis direction side. Have. Therefore, the ground circuit 22a is disposed between the signal circuit 21 and the first via column, and the ground circuit 22b is disposed between the signal circuit 21 and the second via column. The flexible printed wiring board 4 is a via different from the via 60 and connects the conductive adhesive layer 41 and the conductive adhesive layer 51 and at least one via (not shown) connected to the ground circuit 22. 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 position which forms the through hole 61 being different. That is, the through-holes 61 are arranged at intervals along the X-axis direction (one direction) at a position away from the −Y-axis direction ground circuit 22a to the −Y-axis direction side, and the cover coat layer 30 and the insulation are formed. The base material layer 10 is formed so as to penetrate the conductive base material layer 10 and is arranged at an interval along the X-axis direction (one direction) at a position away from the + Y-axis direction side ground circuit 22b toward the + Y-axis direction side. It forms so that the coating layer 30 and the insulating base material layer 10 may be penetrated.

  According to the flexible printed wiring board 4 according to the present embodiment, since the ground circuit 22 is also disposed along with the signal circuit 21 inside the via 60, the influence of radiation noise in the ground circuit 22 can be suppressed. . 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 Embodiment 5 is formed using a double-sided FCCL80, and instead of the electromagnetic shielding sheet 50 in the flexible printed wiring board 1 according to Embodiment 1, copper is used. The layer 23 is provided. The copper layer 23 is provided on the entire lower surface of the insulating base material layer 10. The 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 is provided with at least one via (not shown) that is different from the via 60 and connects the conductive adhesive layer 41 and the copper layer 23 to the ground circuit 22. ing. 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 plurality of through holes 61 are formed. A plurality of through-holes 61 arranged in a row along the X-axis direction (first through-holes) 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 row (second through-hole row) lined up along the X-axis direction between the signal circuit 21 and the ground circuit 22b arranged on the + Y-axis direction side of the signal circuit 21 and the signal circuit 21. It forms so that it becomes. That is, the plurality of through holes 61 are formed so that the signal circuit 21 is disposed between the first through hole column and the second through hole column. In addition, on both sides of the signal circuit 21, a first through-hole row and a second through-hole row are arranged.

  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 through hole 61 is filled with the conductive adhesive of the electromagnetic wave shielding sheet 40 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheet 40 and the conductive adhesive in the through hole 61 are cured. Thereby, as shown in FIG. 11, the conductive adhesive in the through hole 61 is cured to form the 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 FCCL 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. The 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). . 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 plurality of through holes 61 that penetrate the cover coat layer 30, the ground circuit 22, and the insulating base material layer 10 and reach the copper layer 23 are formed. That is, the plurality of through holes 61 are formed so as to penetrate the ground circuit 22a and to be arranged at intervals along the X-axis direction (one direction) along the ground circuit 22a. The plurality of through holes 61 are also formed so as to penetrate the ground circuit 22b and to be arranged along the ground circuit 22b with an interval in the X-axis direction (one direction).

  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 through hole 61 is filled with the conductive adhesive of the electromagnetic wave shielding sheet 40 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheet 40 and the conductive adhesive in the through hole 61 are cured. Thereby, the conductive adhesive in the through hole 61 is cured to form the 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 via 60 and the signal circuit 21. The 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 provided with at least one via (not shown) that is different from the via 60 and connects the conductive adhesive layer 41 and the copper layer 23 to the ground circuit 22. ing. 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 second 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, at a position away from the −Y-axis direction side ground circuit 22a to the −Y-axis direction side, they are arranged at intervals along the X-axis direction (one direction), and an insulating base is formed from the upper surface of the cover coat layer 30. Along the X-axis direction (one direction) at positions away from the + Y-axis direction side from the plurality of through holes 61 that penetrate to the lower surface of the material layer 10 and reach the copper layer 23 and the ground circuit 22b on the + Y-axis direction side A plurality of through holes 61 that 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 are 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 through hole 61 is filled with the conductive adhesive of the electromagnetic wave shielding sheet 40 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheet 40 and the conductive adhesive in the through hole 61 are cured. Thereby, the conductive adhesive in the through hole 61 is cured to form the 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 plurality of vias 60 are provided in a through 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 plurality of vias 60 connect the conductive adhesive layer 41 and the conductive adhesive layer 51.

  The plurality of vias 60 are arranged in rows (spaces) arranged at intervals 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. 1 via) and the signal circuit 21 between the ground circuit 22b arranged on the + Y-axis direction side and the signal circuit 21 and arranged at intervals along the X-axis direction (one direction) ( Second via row). The signal circuit 21 is disposed between the first via 60 column and the second via 60 column. The first via 60 column is disposed between the signal circuit 21 and the ground circuit 22a, and the second via column is disposed between the signal circuit 21 and the ground circuit 22b. The flexible printed wiring board 8 is a via different from the via 60 and connects at least one via (not shown) that connects the conductive adhesive layer 41 and the conductive adhesive layer 51 to the ground circuit 22. 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. In the double-sided FCCL 80, the circuit pattern 20 is provided on one surface 11 of the insulating base material layer 10, and the copper layer 23 is provided on the other surface 12.

  Next, as shown in FIG. 16B, the circuit pattern 20 in the double-sided FCCL 80 is processed to form a signal circuit 21 and a ground circuit 22. 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 plurality of through holes 61 penetrating the coat layer 30 are formed. A plurality of through-holes 61 arranged in a row along the X-axis direction (first through-holes) 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 row (second through-hole row) lined up along the X-axis direction between the signal circuit 21 and the ground circuit 22b arranged on the + Y-axis direction side of the signal circuit 21 and the signal circuit 21. It forms so that it becomes. That is, the plurality of through holes 61 are formed so that the signal circuit 21 is disposed between the first through hole column and the second through hole column. In addition, on both sides of the signal circuit 21, a first through-hole row and a second through-hole row are arranged.

  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 conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 is filled into the through holes 61 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 and the conductive adhesive in the through hole 61 are cured. Thereby, as shown in FIG. 15, the conductive adhesive in the through hole 61 is cured to form the 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 FCCL80, and the positions of the plurality of vias 60 are different from the flexible printed wiring board 8.

  In the flexible printed wiring board 9, the plurality of vias 60 include 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 22 on the other surface 12 side. And in the through hole 61 penetrating the cover coat layer 30 on the other surface 12 side. The plurality of vias 60 connect the conductive adhesive layer 41 and the conductive adhesive layer 51.

  The plurality of vias 60 are provided side by side in the X-axis direction along the ground circuit 22 on the one surface 11 side and the other surface 12 side. In other words, the plurality of vias 60 pass through the ground circuit 22a on the one surface 11 side and the other surface 12 side, and are arranged along the ground circuit 22a at intervals in the X-axis direction (one direction) ( A row of first vias) and the ground circuit 22b on the one surface 11 side and the other surface 12 side, and the rows arranged in the X-axis direction (one direction) at intervals along the ground circuit 22b. (Second via row). 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 plurality of through holes 61 penetrating through 30 are formed. That is, the plurality of through holes 61 also penetrate the ground circuit 22a on the one surface 11 side and the other surface 12 side, and are arranged along the ground circuit 22a with an interval in the X-axis direction (one direction). Form. Further, the plurality of through holes 61 also penetrate the ground circuit 22b on the one surface 11 side and the other surface 12 side, and are arranged along the ground circuit 22b at intervals in the X-axis direction (one direction). Form.

  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 conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 is filled into the through holes 61 by hot pressing. Thereafter, the conductive adhesive of the electromagnetic wave shielding sheets 40 and 50 and the conductive adhesive in the through hole 61 are cured. Thereby, as shown in FIG. 17, the conductive adhesive in the through hole 61 is cured to form the 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, a flexible printed wiring board 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 10 according to the present embodiment uses a double-sided FCCL80, and the positions of the plurality of vias 60 are different from the flexible printed wiring board 8.

  In the flexible printed wiring board 10, the plurality of vias 60 are in the through holes 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 plurality of vias 60 connect the conductive adhesive layer 41 and the conductive adhesive layer 51.

  The plurality of vias 60 are arranged at intervals in the X-axis direction (one direction) at positions away from the −Y-axis direction side ground circuit 22a in the −Y-axis direction side (the first vias). Row) and a row (second via row) arranged at intervals along the X-axis direction (one direction) at a position away from the + Y-axis direction side ground circuit 22b on the + Y-axis direction side. Have. Therefore, the ground circuit 22a is disposed between the signal circuit 21 and the first via column, and the ground circuit 22b is disposed between the signal circuit 21 and the second via column. The flexible printed wiring board 10 is a via different from the via 60 and connects at least one via (not shown) that connects the conductive adhesive layer 41 and the conductive adhesive layer 51 to the ground circuit 22. 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 method for manufacturing the flexible printed wiring board 10 according to the tenth embodiment is the same as that of the eighth embodiment except that the positions where the through holes 61 are formed are different. That is, the through-holes 61 are arranged at intervals along the X-axis direction (one direction) at a position away from the −Y-axis direction ground circuit 22a to the −Y-axis direction side. While forming so as to penetrate the cover coat layer 30, the insulating base material layer 10 and the cover coat layer 30 on the other surface 12 side, at a position away from the ground circuit 22b on the + Y axis direction side to the + Y axis direction side, Arranged at intervals along the X-axis direction (one direction) and formed so as to penetrate 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. To do. The effect of this embodiment is the same as that of Embodiments 4, 7, and 8.

  Next, a simulation result of radiation noise leaking from the gap of the via 60 in the flexible printed wiring board is shown.

  FIG. 19 shows that in a flexible printed wiring board in which a via 60 is arranged between the signal circuit 21 and the ground circuit 22, the signal leaks from the via gap when the frequency of the signal transmitted to the signal circuit is 1 [GHz]. It is the figure which illustrated the result of having simulated the radiation noise, (a) is a via interval 47 [mm], (b) is a via interval 7 [mm], (c) is a via interval Is 3 [mm], and (d) is a via interval of 1 [mm].

  FIG. 20 shows that in the flexible printed wiring board in which the via 60 is disposed between the signal circuit 21 and the ground circuit 22, when the frequency of a signal transmitted to the signal circuit is 10 [GHz], the via leaks from the via gap. It is the figure which illustrated the result of having simulated the radiation noise, (a) is a via interval 47 [mm], (b) is a via interval 7 [mm], (c) is a via interval Is 3 [mm], and (d) is a via interval of 1 [mm].

  The flexible printed wiring board used for the simulation shown in FIGS. 19 and 20 corresponds to, for example, the flexible printed wiring board of the first and fifth embodiments. As shown in FIGS. 19 and 20, the amount of radiation noise leaking from the gap of the via 60 is shown by contrast from black to white. A white part is a part with large radiation noise. The central line portion indicates the signal circuit 21, and the line portions on both sides of the signal circuit 21 indicate the ground circuit 22.

  In the simulation, the width of the signal circuit 21, the ground circuit 22, and the via 60 in the Y-axis direction is 1 mm, and the distance between the signal circuit 21 and the via 60 and the distance between the ground circuit 22 and the via 60 are 0.5 [ mm], and the width of the via 60 in the X-axis direction is 1 [mm]. The length of the flexible printed wiring board in the Y-axis direction is 10 [mm], and the length in the X-axis direction is 50 [mm].

The portion corresponding to the insulating base material layer 10 is a polyimide film (thickness 12.5 [μm], dielectric constant 3.5, dielectric loss tangent 0.007), insulating adhesive (thickness 25 [μm], dielectric constant 3.4, dielectric loss tangent 0.021). ) And polyimide film (thickness 25 [μm], dielectric constant 3.5, dielectric loss tangent 0.007). The portion corresponding to the cover coat layer 30 is made of a polyimide film (thickness 12.5 [μm], dielectric constant 3.5, dielectric loss tangent 0.007) and an insulating adhesive (thickness 25 [μm], dielectric constant 3.4, dielectric loss tangent 0.021). It is supposed to include. The thickness of the conductive adhesive layers 41 and 51 is set to 13 [μm]. The conductivity of the ground circuit 22 is 5.80E + 07.
The simulation was performed under the condition that the ground was installed at the extreme end of the ground circuit 22.

  As shown in FIG. 19A, when the frequency of the signal transmitted to the signal circuit 21 is 1 [GHz] and the via interval is 47 [mm], the −Y axis is viewed from the signal circuit 21. Two vias 60 are set on the direction side, and two vias 60 are set on the + Y axis direction side. Between the signal circuit 21 and the line connecting the via 60 is a gray color (some white is also present), and the radiation noise leaking from the gap of the via 60 is slight.

  Thus, when the signal circuit 21 and the line connecting the via 60 are gray (some white), the radiation noise leaking from the gap of the via 60 is slight and within the allowable range, and the flexible print Assume that the evaluation of the wiring board is A.

  As shown in FIG. 19B, when the via interval is 7 mm, seven vias 60 are set on the −Y axis direction side and seven vias on the + Y axis direction side when viewed from the signal circuit 21. 60 is set. The entire surface between the signal circuit 21 and the line connecting the via 60 is dark gray, and the radiated noise leaking from the gap of the via 60 is small enough to be ignored. Thus, when the entire surface between the signal circuit 21 and the line connecting the via 60 is dark gray, radiation noise leaking from the gap of the via 60 can be ignored, and the evaluation of the flexible printed wiring board is set to A +. .

  As shown in FIG. 19C, when the via interval is 3 [mm], 13 vias 60 are set on the −Y-axis direction side as viewed from the signal circuit 21, and 13 vias on the + Y-axis direction side. Via 60 is set.

  As shown in FIG. 19D, when the via interval is 1 [mm], 25 vias 60 are set on the −Y-axis direction side when viewed from the signal circuit 21, and 25 on the + Y-axis direction side. Via 60 is set. Also in FIGS. 19C and 19D, the radiation noise leaking from the gap of the via 60 is small enough to be ignored. The evaluation of the flexible printed wiring board shown in FIGS. 19C and 19D is A +.

  On the other hand, as shown in FIGS. 20A and 20B, when the frequency of the signal transmitted to the signal circuit is 10 [GHz] and the via interval is 47 [mm] and 7 [mm] The space between the signal circuit 21 and the line connecting the via 60 is completely white, and the radiation noise leaking from the gap between the vias 60 is larger than the allowable value. Thus, when the space between the signal circuit 21 and the line connecting the via 60 is completely white, the radiation noise leaking from the gap of the via 60 is larger than the allowable value, and the flexible printed wiring board is evaluated. B.

  As shown in FIGS. 20C and 20D, when the via interval is 3 [mm] and 1 [mm], the radiated noise leaking from the gap of the via 60 is small enough to be ignored. . Evaluation of the flexible printed wiring board shown to FIG.20 (c) and (d) is A +.

  In addition to 1 [GHz] and 10 [GHz], the frequency of the signal transmitted to the signal circuit was also simulated for 5 [GHz] and 20 [GHz] (Simulation 1).

  In the flexible printed wiring board (corresponding to the second, third, and sixth embodiments) in which the via 60 is connected to the ground circuit 22, the frequency of the signal transmitted to the signal circuit is 1 [GHz], 5 [GHz], 10 In the case of [GHz] and 20 [GHz], a simulation of radiation noise leaking from a via gap was performed (simulation 2).

  Further, in the flexible printed wiring board (corresponding to the fourth and seventh embodiments) in which the via 60 is disposed so as to surround the ground circuit 22 and the signal circuit 21, the frequency of the signal transmitted to the signal circuit is 1 [GHz], 5 Simulation of radiation noise leaking from via gaps was performed for [GHz], 10 [GHz] and 20 [GHz] (Simulation 3).

  In FIG. 21A, the frequency of the signal transmitted to the signal circuit is 1 [GHz], 5 [GHz], 10 [GHz] and 20 [GHz], and the via interval is 47 [mm] and 7 [mm]. FIG. 6 is a diagram illustrating a simulation result of radiation noise leaking from a via gap when 3 [mm] and 1 [mm] are set. As described above, the simulation evaluation results of the flexible printed wiring board due to leakage of radiation noise were classified into A +, A, and B using sensory evaluation based on appearance. The results shown in simulations 1 to 3 are as shown in FIG. 21, and no significant difference was found in simulations 1 to 3.

  As shown in FIG. 21 (a), when the frequency of the signal transmitted to the signal circuit 21 is 1 [GHz], the radiated noise is slight when the via interval is 47 [mm], which is larger than the allowable value. Is small (A), and when the via spacing is 7 [mm], 3 [mm] and 1 [mm], the radiation noise is negligibly small (A +).

  When the frequency of the signal transmitted to the signal circuit 21 is 5 [GHz], the radiation noise is larger than the allowable value (B) when the via interval is 47 [mm], and the via interval is 7 [mm]. , The radiated noise is slight and smaller than the allowable value (A), and the radiated noise is negligibly small (A +) when the via interval is 3 [mm] and 1 [mm].

  When the frequency of the signal transmitted to the signal circuit 21 is 10 [GHz], the radiation noise is larger than the allowable value (B) when the via interval is 47 [mm] and 7 [mm], and the via interval is However, at 3 [mm] and 1 [mm], the radiated noise is negligibly small (A +).

  When the frequency of the signal transmitted to the signal circuit 21 is 20 [GHz], the radiation noise is larger than the allowable value (B) when the via interval is 47 [mm] and 7 [mm], and the via interval is However, at 3 [mm], the radiated noise is slight and smaller than the allowable value (A). When the via spacing is 1 [mm], the radiated noise is negligibly small (A +).

  FIG. 21B is a diagram exemplifying necessary via intervals obtained from simulation results. As shown in FIG. 21B, when the frequency of the signal transmitted to the signal circuit 21 is 1 [GHz] (wavelength is 300 [mm]), it is necessary to suppress the influence of radiation noise. The via interval is 47 [mm]. The frequency of the signal transmitted to the signal circuit 21 is 5 [GHz] (wavelength is 60 [mm]), 10 [GHz] (wavelength is 30 [mm]), and 20 [GHz] (wavelength is 15 [mm]). In this case, the via intervals necessary to suppress the influence of radiation noise are 7 [mm], 3 [mm], and 3 [mm], respectively.

  FIG. 22A is a graph illustrating the relationship between the frequency of the signal transmitted to the signal circuit and the via interval necessary for suppressing the influence of radiation noise, where the horizontal axis indicates the frequency and the vertical axis Indicates a via interval, (b) is a graph illustrating the relationship between the wavelength of a signal transmitted to the signal circuit and the via interval necessary to suppress the influence of radiation noise, and the horizontal axis indicates the wavelength. The vertical axis indicates the via interval.

  As shown in FIG. 22A, by fitting the frequency of the signal transmitted through the signal circuit obtained by simulations 1 to 3 and the necessary via interval, the interval between adjacent vias in the X-axis direction is Y [mm]. Assuming that the frequency of the signal transmitted to the signal circuit is f [GHz], the following relational expression (3) can be derived. The correlation coefficient R is 0.9437.

< ^Equation 3> Y = 40.25 · f ^−0.98 (3)

  Further, as shown in FIG. 22B, by fitting the wavelength of the signal transmitted through the signal circuit obtained by the simulations 1 to 3 and the necessary via interval, the interval between adjacent vias in the X-axis direction is changed to Y [ mm] and the wavelength of the signal transmitted through the signal circuit is X [mm], and the following relational expression (4) can be derived. The correlation coefficient R is 0.9959.

  <Equation 4> Y = 0.16 · X−1.17 (4)

  Therefore, as shown in FIG. 22B, in order to suppress the influence of radiation noise, it is desirable to arrange vias at intervals of vias that satisfy the following formula (5).

  <Equation 5> Y ≦ 0.16 · X−1.17 (5)

  In the simulation, the thickness of the insulating base material layer 10 is 62.5 μm, and the thickness of the cover coat layer 30 is 37.5 μm. Therefore, the distance between the conductive adhesive layer 41 and the conductive adhesive layer 51 (in the case of the printed wiring board of the first to fourth embodiments) or the distance between the conductive adhesive layer 41 and the copper layer 23 (the fifth to fifth embodiments). The gap between vias is much larger than in the case (7). Therefore, leakage of radiation noise is considered to depend on the via interval rather than the interval between the upper and lower conductive layers.

  Further, when the via interval is 47 [mm], 7 [mm], 3 [mm], and 1 [mm], the width of the via in the X-axis direction is 1 [mm]. Therefore, when the via interval is 47 [mm], 7 [mm], 3 [mm], and 1 [mm], the interval between adjacent vias 60 in the X-axis direction is the width of the via 60 in the X-axis direction. On the other hand, it corresponds to 47 times, 7 times, 3 times and 1 time. Further, when the wavelength of the signal transmitted through the signal circuit 21 is 15 [mm], 30 [mm], 60 [mm], and 300 [mm], the wavelength of the signal transmitted through the signal circuit 21 is that of the via 60. It corresponds to 15 times, 30 times, 60 times and 300 times the width in the X-axis direction.

The results obtained from the simulation will be described below.
A signal transmitted through the signal circuit 21 when the wavelength of the signal transmitted through the signal circuit 21 is 15 [mm] to 300 [mm] under the condition that the width of the via 60 in the X-axis direction is approximately 1 [mm]. When the wavelength of is 15 to 300 times the width of the via 60 in the X-axis direction, leakage of radiation noise could be suppressed.

  Further, when the distance between adjacent vias 60 in the X-axis direction is 1 [mm] to 3 [mm] under the condition that the width of the via 60 in the X-axis direction is approximately 1 [mm], When the interval between adjacent vias 60 is 1 to 3 times the width of the vias 60 in the X-axis direction, leakage of radiation noise could be suppressed.

  Furthermore, when the gap between the vias 60 adjacent to each other in the X-axis direction is about 1 [mm] under the condition that the width of the vias 60 in the X-axis direction is about 1 [mm], the adjacent vias 60 in the X-axis direction. The leakage of radiation noise was able to be suppressed when the distance between was approximately 1 times the width of the via 60 in the X-axis direction.

  Further, when the wavelength of the signal transmitted through the signal circuit 21 is 60 [mm] to 300 [mm] under the condition that the width of the via 60 in the X-axis direction is approximately 1 [mm], the signal circuit 21 is transmitted. When the wavelength of the signal to be transmitted is 60 to 300 times the width of the via 60 in the X-axis direction, leakage of radiation noise could be suppressed.

  Further, when the distance between adjacent vias 60 in the X-axis direction is 1 [mm] to 7 [mm] under the condition that the width of the via 60 in the X-axis direction is approximately 1 [mm], When the interval between adjacent vias 60 is 1 to 7 times the width of the vias 60 in the X-axis direction, leakage of radiation noise could be suppressed.

  Further, when the wavelength of the signal transmitted through the signal circuit 21 is approximately 300 [mm] under the condition that the width of the via 60 in the X-axis direction is approximately 1 [mm], the wavelength of the signal transmitted through the signal circuit 21 is approximately 300 [mm]. However, when the width of the via 60 in the X-axis direction was approximately 300 times, leakage of radiation noise could be suppressed.

  When the distance between adjacent vias 60 in the X-axis direction is 1 [mm] to 47 [mm] under the condition that the width of the vias 60 in the X-axis direction is approximately 1 [mm], the vias 60 are adjacent in the X-axis direction. When the interval between the vias 60 is 1 to 47 times the width of the vias 60 in the X-axis direction, leakage of radiation noise can be suppressed.

  In the simulation 1, the distance between the signal circuit 21 and the via is 0.5 [mm]. In the simulation 2, the distance between the signal circuit 21 and the via is 2.0 [mm]. In the simulation 3, the distance between the signal circuit 21 and the via is 3.5 [mm]. Since there was no significant difference in the results of simulations 1 to 3, when the distance between the signal circuit 21 and the via 60 is in the range of 0.5 [mm] to 3.5 [mm], the above formulas for wavelength and via spacing are used. Is considered to hold.

  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, the optimum value can be applied to the numerical range of the wavelength of the signal transmitted through the signal circuit 21 and the interval between the adjacent vias 60 in the X-axis direction in the simulation result from the description of FIGS.

  For example, when the frequency is approximately 1 [GHz] (wavelength 300 [mm]), the via interval is preferably 47 [mm] to 1 [mm], and more preferably 7 [mm] to 1 [mm]. . When the frequency is approximately 5 [GHz] (wavelength 60 [mm]), the via interval is preferably 7 [mm] to 1 [mm], and more preferably 3 [mm] to 1 [mm]. . In such cases, when the frequency range is expanded and the frequency is approximately 1 to 5 [GHz] (wavelength 60 to 300 [mm]), the via spacing is 7 [mm] to 1 [mm]. Of course, it can be said that 3 [mm] to 1 [mm] is more preferable. 21 and 22 can be applied by selecting an optimal numerical range as appropriate.

  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.

  In the embodiment shown in the present specification, the interval between the vias 60 may not be equal. Further, the first via row and the second via row sandwiching the signal circuit 21 may not be at the same interval. By doing so, resonance can be suppressed.

  The frequencies shown in this specification are described in the wavelength in vacuum.

1, 1a, 2, 3, 4, 5, 6, 7 Flexible printed wiring board 10 Insulating substrate 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 Vias 61, 61a, 61b, 61c, 61d Through hole 70 Single side 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

The 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 , that is, from the upper surface of the cover coat layer 30 to the upper surface of the ground circuit 22a. Are connected to the ground circuit 22a. The 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. . The via 60c (second upper via) extends from the upper surface of the cover coat layer 30 to the lower surface of the cover coat layer 30 , that is, penetrates from the upper surface of the cover coat layer 30 to the upper surface of the ground circuit 22b. Are connected to the ground circuit 22b. The 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. .

(Embodiment 10)
Next, a flexible printed wiring board 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 9 a according to the present embodiment uses a double-sided FCCL 80, and the positions of the plurality of vias 60 are different from the flexible printed wiring board 8.

In the flexible printed wiring board 9a , the plurality of vias 60 are formed in the through holes 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 plurality of vias 60 connect the conductive adhesive layer 41 and the conductive adhesive layer 51.

The plurality of vias 60 are arranged at intervals in the X-axis direction (one direction) at positions away from the −Y-axis direction side ground circuit 22a in the −Y-axis direction side (the first vias). Row) and a row (second via row) arranged at intervals along the X-axis direction (one direction) at a position away from the + Y-axis direction side ground circuit 22b on the + Y-axis direction side. Have. Therefore, the ground circuit 22a is disposed between the signal circuit 21 and the first via column, and the ground circuit 22b is disposed between the signal circuit 21 and the second via column. The flexible printed wiring board 9a has at least one via (not shown) that is different from the via 60 and connects the conductive adhesive layer 41 and the conductive adhesive layer 51 to the ground circuit 22. 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 through holes 61 are formed are different. That is, the through-holes 61 are arranged at intervals along the X-axis direction (one direction) at a position away from the −Y-axis direction ground circuit 22a to the −Y-axis direction side. While forming so as to penetrate the cover coat layer 30, the insulating base material layer 10 and the cover coat layer 30 on the other surface 12 side, at a position away from the ground circuit 22b on the + Y axis direction side to the + Y axis direction side, Arranged at intervals along the X-axis direction (one direction) and formed so as to penetrate 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. To do. The effect of this embodiment is the same as that of Embodiments 4, 7, and 8.

1, 1a, 2, 3, 4, 5, 6, 7, 8, 9 , 9a Flexible printed wiring board 10 Insulating substrate 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 Cover lay 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 Vias 61, 61a, 61b, 61c, 61d Through 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 (20)

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 plurality of conductive vias penetrating from the upper surface of the second insulating layer to the lower surface of the first insulating layer and connecting the second conductive layer and the first conductive layer;
With
The plurality of vias have a first via row arranged at intervals along the one direction, and a second via row arranged at intervals along the one direction,
The signal circuit is disposed between the first via row and the second via row;
The interval between the vias adjacent in the one direction is Y,
When the wavelength of the signal transmitted through the signal circuit is X, the following equation (1),
<Equation 1> Y ≦ 0.16 · X−1.17 (1)
Flexible printed wiring board that meets the requirements. 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 via row is disposed between the signal circuit and the first ground circuit;
The flexible printed wiring board according to claim 1, wherein the second via row 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,
A plurality of vias constituting the first via row pass through the first ground circuit and are arranged along the first ground circuit.
2. The flexible printed wiring board according to claim 1, wherein the plurality of vias constituting the second via row 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 via row,
The flexible printed wiring board according to claim 1, wherein the second ground circuit is disposed between the signal circuit and the second via row. 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 plurality of conductive first upper vias that penetrate from the upper surface of the second insulating layer to the lower surface of the second insulating layer and connect the second conductive layer and the first ground circuit;
A plurality of conductive first lower vias that penetrate from the upper surface of the first insulating layer to the lower surface of the first insulating layer and connect the first ground circuit and the first conductive layer;
A plurality of conductive second upper vias that penetrate from the upper surface of the second insulating layer to the lower surface of the second insulating layer and connect the second conductive layer and the second ground circuit;
A plurality of conductive second lower vias that penetrate from the upper surface of the first insulating layer to the lower surface of the first insulating layer and connect the second ground circuit and the first conductive layer;
With
The plurality of first upper vias and the plurality of first lower vias are arranged side by side along the first ground circuit at intervals,
The plurality of second upper vias and the plurality of second lower vias are arranged side by side along the second ground circuit at intervals,
The interval between the first upper via, the first lower via, the second upper via, and the second lower via that are adjacent in the one direction is Y,
When the wavelength of the signal transmitted through the signal circuit is X, the following equation (2):
<Equation 2> Y ≦ 0.16 · X−1.17 (2)
Flexible printed wiring board that meets the requirements. 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 plurality of conductive vias penetrating from the upper surface of the second insulating layer to the lower surface of the first insulating layer and connecting the second conductive layer and the first conductive layer;
With
The plurality of vias have a first via row arranged at an interval along the one direction and a second via row arranged at an interval along the one direction;
The first via row is disposed between the signal circuit and the first ground circuit;
The second via row 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 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.   The flexible printed wiring board according to claim 1, wherein a wavelength of a signal transmitted through the signal circuit is 15 mm to 300 mm.   The flexible printed wiring board according to any one of claims 1 to 10, wherein a wavelength of a signal transmitted through the signal circuit is 15 to 300 times the width of the via in the one direction.   The flexible printed wiring board according to claim 1, wherein an interval between the vias adjacent in the one direction is 1 mm to 3 mm.   The flexible printed wiring board according to claim 1, wherein an interval between the vias adjacent in the one direction is 1 to 3 times a width of the via in the one direction.   The flexible printed wiring board according to any one of claims 1 to 9, wherein a wavelength of a signal transmitted through the signal circuit is 60 mm to 300 mm.   The flexible printed wiring board according to claim 1, wherein the wavelength of the signal transmitted through the signal circuit is 60 to 300 times the width of the via in the one direction.   The flexible printed wiring board according to claim 1, wherein an interval between the vias adjacent to each other in the one direction is 1 mm to 7 mm.   The flexible printed wiring according to any one of claims 1 to 9 and 14 to 16, wherein an interval between the vias adjacent in the one direction is 1 to 7 times a width of the via in the one direction. Board. 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 plurality of through holes penetrating from the upper surface of the second insulating layer to the lower surface of the first insulating layer;
With
The plurality of through-holes become a first through-hole row arranged at intervals along the one direction and a second through-hole row arranged at intervals along the one direction. Formed as
Forming the plurality of through holes such that the signal circuit is disposed between the first through hole column and the second through hole column;
The interval between the through holes adjacent in the one direction is Y,
When the wavelength of the signal transmitted through the signal circuit is X, the following equation (3):
<Equation 3> Y ≦ 0.16 · X−1.17 (3)
To satisfy
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 through 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 through hole; and
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 plurality of through holes penetrating from the upper surface of the second insulating layer to the lower surface of the first insulating layer and reaching the first conductive layer;
With
The plurality of through-holes become a first through-hole row arranged at intervals along the one direction and a second through-hole row arranged at intervals along the one direction. Formed as
Forming the plurality of through holes such that the signal circuit is disposed between the first through hole column and the second through hole column;
The interval between the through holes adjacent in the one direction is Y,
When the wavelength of the signal transmitted through the signal circuit is X, the following equation (4):
<Equation 4> Y ≦ 0.16 · X−1.17 (4)
To satisfy
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 through 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 through hole; and
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 1-17 was connected.