JP2023049844A - Flexible wiring board, electronic module, electronic unit and electronic apparatus - Google Patents

Abstract

To improve functionality of a flexible wiring board.SOLUTION: The present invention relates to an electronic module comprising: a flexible wiring board which includes a signal line, a conductive part overlapping the signal line in a planar view and a ground line; and an electronic component causing a signal, where the wavelength in the case of flowing in the signal line is a wavelength λ, to flow to the signal line. In the electronic module, the flexible wiring board and the electronic component are connected. The flexible wiring board includes a connection part electrically connecting the conductive part with the ground line, and the conductive part includes an open end. When a length from the connection part to the open end in an extension direction of the signal line is defined as L, a relation of the wavelength λ and the length L is λ/4-λ/8≤L≤λ/4+λ/8.SELECTED DRAWING: Figure 3

Description

The present invention relates to flexible wiring boards.

Electronic devices such as mobile phones, smart phones, tablet terminals, and digital cameras use flexible wiring boards as signal transmission paths. A flexible wiring board is provided with a conductive layer as a shield layer in addition to signal lines for the purpose of improving electrical and/or mechanical functions.

Patent Document 1 proposes a flexible printed wiring board in which a wiring conductor pattern and a land electrically connected through a through hole are divided by a slit.

JP 2017-183420 A

If a slit is provided to divide the land, the noise emitted from the flexible printed wiring board may affect the devices and equipment around the flexible printed wiring board, depending on the length from the connection between the land and the through hole to the slit. The inventors have found that there is a possibility that SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the functionality of a flexible wiring board.

A first means for solving the above problems is a flexible wiring board having a signal line, a conductive portion overlapping the signal line in a plan view, and a ground line, and when the signal line flows through the signal line, and an electronic component for transmitting a signal having a wavelength of λ, wherein the flexible wiring board and the electronic component are connected, wherein the flexible wiring board connects the conductive portion and the ground line A connection portion for electrical connection is provided, the conductive portion has an open end, and the wavelength λ is the length in the direction in which the signal line extends from the connection portion to the open end. and the length L is λ/4−λ/8≦L≦λ/4+λ/8.

A second means for solving the above problem is a flexible wiring board having a signal line extending in a first direction, a conductive portion overlapping the signal line in plan view, and a ground line; and an electronic component for transmitting a signal of wavelength λ, wherein the flexible wiring board and the electronic component are connected, wherein the flexible wiring board electrically connects the conductive portion and the ground line. the conductive portion has a linear portion extending in a second direction intersecting the first direction; the conductive portion has an open end; The relationship between the wavelength λ and the length L is λ/4−λ/8≦L≦λ/4+λ/8, where L is the length in the second direction up to .lamda./4+λ/8.

A third means for solving the above-mentioned problems has a signal line, a conductive portion overlapping the signal line in a plan view, and a ground line, and the wavelength output from the electronic component connected to the signal line is A flexible wiring board that transmits a signal of λ, wherein the flexible wiring board includes a connecting portion that electrically connects the conductive portion and the ground line, the conductive portion has an open end, and the connection When the length in the direction in which the signal line extends from the portion to the open end is L, the relationship between the wavelength λ and the length L is λ/4−λ/8≦L≦λ/4+λ/ 8.

A fourth means for solving the above problems is a flexible wiring board having a signal line, a conductive portion overlapping the signal line in plan view, and a ground line, wherein the flexible wiring board includes the conductive portion and the ground line, wherein the conductive portion has an open end, and the length of the conductive portion in the direction in which the signal line extends is adjacent to the conductive portion. is longer than the distance from the conductive portion of the

A fifth means for solving the above problems is a flexible wiring board having a signal line, a conductive portion overlapping the signal line in plan view, and a ground line, wherein the flexible wiring board includes the conductive portion and the ground line, the conductive portion has an open end, and the length in the direction in which the signal line extends from the connection portion to the open end is It is characterized by being 8 mm or more and 23 mm or less, or 24 mm or more and 38.3 mm or less.

ADVANTAGE OF THE INVENTION According to this invention, when improving the functionality of a flexible wiring board, an advantageous technique can be provided.

It is a perspective view of a unit according to the present embodiment. 2(a) is a cross-sectional view of the wiring board taken along line AA of FIG. 1; FIG. 2B is a cross-sectional view of the wiring board taken along line BB of FIG. 1; FIG. 2(c) is a cross-sectional view of the wiring board taken along line CC of FIG. 1; FIG. 1 is a top view of a wiring board according to a first embodiment; FIG. FIG. 10 is a top view of a wiring board according to a second embodiment; It is a top view showing a modification of the wiring board according to the embodiment. 6 is a cross-sectional view of the wiring board taken along line DD in FIG. 5; FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a system used to evaluate radiation noise characteristics of a flexible printed wiring board of an example and a flexible printed wiring board of a comparative example; BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of the apparatus used for evaluating the flexibility of the flexible printed wiring board of an Example, and the flexible printed wiring board of a comparative example. FIG. 11 is a top view of a wiring board according to Example 3; FIG. 11 is a top view of a wiring board according to Example 4; FIG. 11 is a top view of a wiring board according to Example 5; 3 is a top view of a wiring board according to Comparative Example 1; FIG. 4 is a table showing evaluation results in Examples 1 to 12 and Comparative Example 1. FIG. 1 is an explanatory diagram of a digital camera that is an imaging device as an example of an electronic device according to an embodiment; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the form described below is one embodiment of the invention, and is not limited to this. Common configurations will be described with reference to a plurality of drawings, and descriptions of configurations to which common reference numerals are assigned will be omitted as appropriate. Different matters with the same name can be distinguished by adding "○", such as the first matter and the second matter.

<First embodiment>
FIG. 1 is a perspective view of an electronic unit 100 having a wiring board 200. FIG. Wiring board 200 is, for example, a flexible printed wiring board. Note that the method of forming the wiring on the wiring board 200 is not limited to printing, and may be pre-formed electric wires, and the wiring board 200 may be a flat cable.

The electronic unit 100 includes a circuit board 101 , a circuit board 102 , and a wiring board 200 electrically connecting the circuit boards 101 and 102 . Circuit board 101 and circuit board 102 are, for example, printed circuit boards. An article in which wiring board 200 and at least one of circuit board 101 and circuit board 102 are connected together can be referred to as electronic module 10 . For example, the electronic unit 100 can be configured by preparing the electronic module 10 in which the wiring board 200 is connected to the circuit board 101 and further connecting the wiring board 200 of the electronic module 10 to the circuit board 102 . Further, an electronic device including the electronic unit 100 can be configured.

As shown in FIG. 1, wiring board 200 extends in the X direction, which is the longitudinal direction. The wiring board 200 has a plurality of signal lines 22, and each signal line 22 extends in the X direction. The plurality of signal lines 22 are arranged at intervals in the Y direction, which is the lateral direction, perpendicular to the X direction. The Z direction orthogonal to the X and Y directions is the thickness direction of wiring board 200 . Wiring board 200 is flexible and bendable.

Wiring board 200 has one end 201 in the X direction and the other end 202 in the X direction.

A connector 112 is mounted on the wiring board 110 . Connector 112 is electrically connected to semiconductor device 111 by a conductor pattern on wiring board 110 . A connector 122 is mounted on the wiring board 120 in the same manner as the wiring board 110 . Connector 122 is electrically connected to semiconductor device 121 by a conductor pattern on wiring board 120 .

Wiring board 110 and wiring board 120 are, for example, rigid wiring boards, and a printed wiring board (rigid printed wiring board) including a resin substrate or a ceramic substrate can be used.

With the above configuration, semiconductor device 111 and semiconductor device 121 are electrically connected via wiring board 110, wiring board 200, and wiring board 120 so as to be able to communicate with each other. At this time, wiring boards 110 and 120 may be connected directly to wiring boards 110 and 120 by soldering without connectors 112 and 122 . In this embodiment, wiring boards 110 and 200 may be directly connected by soldering, but wiring boards 120 and 200 are connected via a connector.

2A is a cross-sectional view of wiring board 200 in FIG. 1 along line AA, FIG. 2B is a cross-sectional view along line BB of wiring board 200 in FIG. 1, and FIG. 2 is a CC cross-sectional view of wiring board 200 in FIG. FIG. 3 is a top view of wiring board 200 . The wiring board 200 is composed of a wiring board body 210 and a conductive layer 220, which will be described in detail below.

Wiring board 200 according to the present embodiment will be described with reference to FIGS. Wiring board body 210 has insulating layer 12 , insulating layer 13 , insulating layer 14 , and a plurality of signal lines 22 described above. The insulating layers 12, 13 and 14 are made of an electrically insulating material. Each signal line 22 is made of a conductive material. The wiring board main body 210, that is, the insulating layers 12, 13, 14 and the plurality of signal lines 22 are formed by extending in the X direction. The plurality of signal lines 22 are arranged inside the insulating layer 13 at intervals in the Y direction, but do not necessarily need to be arranged inside the insulating layer 13 .

Although two of the plurality of signal lines 22 are illustrated in FIGS. 2 and 3, the number of signal lines in this embodiment is not limited to two, and three or more signal lines are shown. It is also applicable to The insulating layers 12, 13, 14 are formed in a sheet shape and have a pair of main surfaces 231, 232 extending in the X direction. The conductive layer 220 may be arranged at a position in contact with either one of the pair of main surfaces 231 and 232 , and is arranged at a position in contact with the main surface 231 in the present embodiment. Note that the conductive layer 220 may be arranged on each of the pair of main surfaces 231 and 232 .

The plurality of insulating layers 12 , 13 , 14 are in contact with each other and are each insulating substrates, and the insulating layer 12 has a pair of main surfaces 241 , 242 . A plurality of signal lines 22 are arranged on the main surface 242 .

In this embodiment, the insulating layer 13 is arranged between the insulating layer 12 and the insulating layer 14 . The insulating layer 13 has a function of bonding the insulating layer 12 and the insulating layer 14 together. Note that the insulating layer 13 may be omitted if the insulating layer 14 has an adhesive function.

Each signal line 22 will be described in detail below. For each signal line 22, wiring having a band capable of transmitting the digital data signal to be handled is used. As the amount of signal transmission increases, it is preferable to construct a differential signal wiring in which a pair of signal lines 22 out of the plurality of signal lines 22 constitutes one set. Note that the plurality of signal lines 22 may include wiring for transmitting single-ended signals such as control signals and response signals. Wiring board 200 also has ground line 133 in addition to signal line 22 , and signal line 22 and ground line 133 are arranged on main surface 242 .

Although the method of forming the signal line 22 is not particularly limited, the signal line 22 can be formed by, for example, bonding of metal foil, metal plating, an inkjet process, or the like. When a copper foil is used as the metal foil, a film bonded with an adhesive or the like can be used, and the required transmission line pattern can be formed by a photolithographic etching process. Alternatively, when using an inkjet process, a polymer ink containing metal particles is drawn in a required pattern, and the pattern is baked at a temperature equal to or lower than the glass transition point (Tg) of the insulating layer 12 to form the pattern.

Although the thickness of the signal line 22 is not particularly limited, it is preferably 0.1 μm or more and 20 μm or less, for example.

Next, the connecting portion 17 will be described with reference to FIGS. 2(b) and 3. FIG. The connection portion 17 is a portion that electrically connects the conductive portion 15 of the conductive layer 220 and the ground line 133 . In FIG. 3, the connection part 17 is arranged on the non-formation region 20 side of the conductive layer 220, but it may be arranged in the center of the conductive layer 220, and the arrangement position is not limited. Although the connection portion 17 is made of the same material as the conductive portion 15 in this embodiment, it may be made of any material as long as it has conductivity. The diameter R of the connecting portion 17 is preferably 0.5 mm or more and 3.5 mm or less, more preferably 0.7 mm or more and 3 mm or less.

The conductive layer 220 will be described in detail below. The conductive layer 220 is a sheet-like member, includes the conductive portion 15 and is covered with the insulating layer 16 . The conductive portion 15 is arranged at a position in contact with the main surface 231 of the insulating layer 14, and may be arranged at least at a position facing the signal line 22 or at a position overlapping the signal line 22 in plan view. The overlapping direction in plan view is, for example, the thickness direction of wiring board 200 . The conductive portion 15 is provided inside the insulating layer 16 . Insulating layer 16 is a protective layer surrounding conductive portion 15 so that conductive portion 15 does not come into contact with members surrounding wiring board 200, and is made of a member having electrical insulation.

Conductive portion 15 has conductivity and is used as a path for a return current of a signal flowing through signal line 22 . electrically connected.

The conductive portion 15 also functions as a shield layer that shields electromagnetic noise emitted from the signal line 22 . However, when the conductive layer 220 covers the entire surface of the wiring board 200 facing the signal line 22, radiation noise can be suppressed compared to the case where the conductive layer 220 is not covered, but the flexibility of the wiring board 200 is reduced. There is a risk of it being damaged.

Therefore, the wiring board 200 according to the present embodiment has a region where the conductive portion 15 is formed as shown in FIGS. 2(a) and 2(b), and A non-formation region 20 in which the conductive portion 15 is not formed is provided. As shown in FIG. 3, conductive portions 15 and non-formation regions 20 are arranged alternately in the X direction, which is the longitudinal direction of wiring board 200 . Conductive portion 15 and non-formation region 20 each extend continuously in the Y direction of wiring board 200 . By dividing the conductive portion 15 into a plurality of portions by the non-formation regions 20, the rigidity against bending in the X direction can be reduced, and the flexibility of the wiring board 200 when bending in the X direction along the bending lines in the Y direction can be improved. . The boundary between the conductive layer 220 and the non-formation region 20 is the open end 23 and the open end 24 .

In addition, in the present embodiment, the length L1 in the X direction from the connection portion 17 to the open end 23 is within the range of ±λ ₁ /8 of 1/4 of the signal wavelength λ ₁ flowing through the wiring board 200. is designed to be As a result, radiation noise radiated by digital signals transmitted at high speed via wiring board 200 can be suppressed.

By providing the non-formation region 20 and setting the length L1 in the X direction from the connecting portion 17 to the open end 23 to be λ ₁ /4±λ ₁ /8, it is possible to suppress radiation noise and improve flexibility. A wiring board 200 can be provided. Here, the length of λ ₁ /4±λ _1/8 means that the relationship between the length L1 and the wavelength λ ₁ is λ ₁ /4−λ ₁ /8≦L1≦λ ₁ /4+λ _1/8 . is shown.

Although the details will be described later, a good noise suppression effect can be obtained when the digital signal transmitted through the wiring board 200 is in the 2 to 8 GHz band. A higher noise suppression effect can be obtained. In such a case, the length L1 in the X direction from the connecting portion 17 to the open end 23 is 5.8 mm or more and 23 mm or less when the frequency is 5.3 GHz, and 24 mm or more and 38.5 mm when the frequency is 2.4 GHz. It may be in the range of 3 mm or less. The length L2 of the non-forming region 20 is equal to the length from the open end 23 to the open end 24 adjacent to the open end 23 .

As the length L1 in the _X direction from the connection portion 17 to the open end 23, if it is _{λ 1} /4±λ ₁ /16, the noise can be further suppressed. is preferred.

If the length L1 in the X direction from the connecting portion 17 to the open end 23 is out of the range of λ ₁ /4±λ ₁ /8, the frequency band exhibiting a good noise suppression effect deviates greatly, resulting in a good noise suppression effect. Inhibition effect may not be obtained.

As shown in FIG. 3, the length L1 in the +X direction from the connecting portion 17 to the open end 23 is λ ₁ /4±λ ₁ /8, and the length in the −X direction from the connecting portion 17 to the open end 24 is If it is 0, a good noise suppression effect can be obtained. However, the length in the X direction of either one of the connection portion 17 to the _open ends 23 and 24 should satisfy λ ₁ /4±λ ₁ /8. /4±λ ₁ /8 does not necessarily have to be satisfied. Even in that case, the noise suppression effect can be obtained.

The length L1 from the connecting portion 17 to the open end 23 is the length in the X direction, and even if the length in the Y direction satisfies λ ₁ /4±λ ₁ /8, the noise suppression effect cannot be obtained. Can not.

The reason why the length L1 in the X direction from the connecting portion 17 to the open end 23 should be λ ₁ /4±λ ₁ /8 will be explained below.

A noise current flows through the signal line 22 in addition to a digital signal current for transmitting information. When a noise current flows, a displacement current flows due to the capacitance between the signal line 22 and the conductive portion 15 , and a return current flows through the conductive portion 15 in a direction opposite to the current flowing through the signal line 22 . The return current always becomes a node at the location of connection 17 which is connected to ground. Therefore, when the non-formation region 20 is provided as in the present embodiment, the return current is reflected at the open ends 23 and 24, and the reflected current cancels the return current, thereby obtaining a high noise suppression effect. can. Here, the case where the return current is in the opposite direction of the noise current is shown, but the return current can also occur in the same direction as the noise current. When the length L1 in the X direction from the connecting portion 17 to the open end 23 is λ ₁ /4±λ ₁ /8, the waves of the current reflected by the open ends 23 and 24 cancel out the waves of the return current. , a high noise suppression effect can be obtained. More preferably, the length L1 in the X direction from the connecting portion 17 to the open end 23 is within the range of λ ₁ /4±25%.

In this embodiment, the frequency f is set to 2.4 GHz or 5.3 GHz, and the wavelength _λ1 is set to 47 mm or 102 mm. The frequency f may be 2 GHz or more and 3 GHz or less, or 5 GHz or more and 6 GHz or less, and the wavelength λ ₁ may be 45 mm or more and 50 mm or less, or 100 mm or more and 105 mm or less.

The length L2 of the non-formation region 20 is preferably 0.1 mm or more and 10 mm or less in the X direction, and more preferably 0.2 mm or more and 6 mm or less. Further, it is more preferable if the distance is 0.5 mm or more and 5 mm or less in the X direction. If the length L2 of the non-formation region is 0.1 mm or less, electromagnetic coupling occurs between the adjacent conductive layers 220, and a sufficient noise suppression effect cannot be obtained. If the length L2 of the non-formation region 20 is 10 mm or more, noise leaks from the non-formation region 20, and a good noise suppression effect cannot be obtained.

In addition, the length L2 of the non-formation region 20 is preferably λ ₁ /500 or more and λ ₁ /5 or less, more preferably λ ₁ /300 or more and λ ₁ /9 or less in the X direction.

A length L1 in the X direction from the connection portion 17 to the non-formation region 20 is longer than the length L2 of the non-formation region 20, preferably 2 to 120 times, and preferably 2.4 to 60 times. Within this range, noise leakage from the non-formation region 20 can be suppressed, and a good noise suppression effect can be obtained.

The length of the conductive layer 220 is the sum of the length L1 from the connecting portion 17 to the open end 23 and the diameter R of the connecting portion 17 .

A method for manufacturing the conductive portion 15 is not particularly limited, and it is preferable to directly pattern the conductive portion 15 on the wiring board main body 210 by various printing methods such as a screen printing method and an inkjet printing method. Alternatively, the conductive film on wiring board body 210 may be patterned by a photolitho-etching process. Conductive portion 15 that has been processed into a predetermined shape in advance by die-cutting or braiding may be attached to wiring board main body 210 .

For example, methods for forming the conductive portion 15 on the insulating layer 14 include a subtractive method, an electroless plating method, an electrolytic plating method, and physical vapor deposition methods such as vacuum deposition and sputtering. Alternatively, a method of laminating conductive fibers, a screen printing method, or the like can be employed. Metals that constitute the conductive portion 15 include copper, aluminum, nickel, iron, gold, silver, platinum, tungsten, chromium, titanium, tin, lead, and palladium. May be combined. Of these, silver or copper is preferred from the viewpoint of conductivity and low cost.

The thickness of the conductive portion 15 is preferably 1 μm or more, more preferably 5 μm or more. If the thickness is less than 1 μm, sufficient bending resistance cannot be obtained. Further, if the thickness of the conductive portion 15 is 20 μm or less, the thickness of the insulating layer 16 can be reduced, so that the wiring board 200 with higher flexibility can be provided. The surface resistance value of the conductive portion 15 is preferably 1Ω/□ or less, more preferably 0.1Ω/□ or less. If the surface resistance value exceeds 1 Ω/□, the resistance loss received by the return current at the time of signal transmission increases, degrading the transmission characteristics.

The insulating layers 12, 13, 14 and 16 will be described in detail below.

The insulating layer 12 will be described in detail. The material of the insulating layer 12, which is an insulating substrate, is preferably resin. Examples of resins include polyimide-based resins such as polyimide, polyamide, and polyamide-imide, thermosetting resins such as epoxy, and thermoplastic resins such as liquid crystal polymers. Among these, polyimide or liquid crystal polymer is preferred. Polyimide has excellent heat resistance and mechanical properties, and is easily commercially available. Liquid crystal polymers are suitable for high-speed signal transmission applications because of their low relative permittivity, and their low hygroscopicity and excellent dimensional stability.

The thickness of the insulating layer 12 is not particularly limited, but preferably ranges from 10 μm to 100 μm. If the thickness is less than 10 μm, the distance between the signal line 22 and the conductive portion 15 becomes short, and the characteristic impedance value may become excessively large. On the other hand, if the thickness exceeds 100 μm, the rigidity of the resin increases, and the flexibility may become insufficient. More preferably, it is in the range of 12 μm or more and 75 μm or less.

Next, the insulating layer 13 will be described in detail. The insulating layer 13 is an adhesive layer provided between the insulating layer 12 and the insulating layer 14 and the signal line 22 . That is, the insulating layer 13 is a cured adhesive. The insulating layer 13 preferably has high electrical insulation. Examples of adhesives used to form the insulating layer 13 include acrylonitrile-butadiene rubber (NBR)-based adhesives, polyamide-based adhesives, polyester-based adhesives, acrylic-based adhesives, polyester-polyurethane-based adhesives, and silicone-based adhesives. is mentioned.

Preferably, the insulating layer 13 can sufficiently cover the signal line 22, which is a transmission line, and is smooth. Therefore, the thickness of the insulating layer 13 in the Z direction is preferably 2 μm or more and 50 μm or less. When the thickness of the insulating layer 13 is 2 μm or more, the adhesive can be sufficiently embedded between the signal lines 22 , and the insulating layer 13 can be firmly adhered. Moreover, when the thickness of the insulating layer 13 is 50 μm or less, it is possible to suppress the adhesive from seeping out from between the insulating layers 12 and 14 to the sides. From the above point of view, it is more preferable that the thickness of the insulating layer 13 in the Z direction is 5 μm or more and 30 μm or less.

The method of forming the insulating layer 13 is not particularly limited, but examples include a method of bonding sheet-like adhesives together and curing, a method of applying a liquid adhesive by a dispenser or a printing method, and a method of curing with heat or ultraviolet rays. be done.

Next, the insulating layer 14 will be described in detail. As the insulating layer 14, plastic and/or insulating resin can be used. Plastics used for the insulating layer 14 include so-called engineering plastics. Examples of plastics used for the insulating layer 14 include polypropylene, crosslinked polyethylene, polyester, polybenzimidazole, polyamide, polyimide, polyimideamide, and polyetherimide. Examples of plastics used for the insulating layer 14 include polyphenylene sulfide (PPS), polyethylene naphthalate (PEN), and polyetheretherketone (PEEK). From the viewpoint of low cost, it is preferable to use a polyester film. From the viewpoint of excellent flame retardancy, it is preferable to use a polyphenylene sulfide film. If further heat resistance is required, it is preferable to use an aramid film or a polyimide film.

The insulating resin used for the insulating layer 14 may be any resin having electrical insulating properties, and examples thereof include thermosetting resins and ultraviolet curable resins. Thermosetting resins include phenol resins, acrylic resins, epoxy resins, melamine resins, silicone resins, and acrylic-modified silicone resins. Examples of UV-curable resins include epoxy acrylate resins, polyester acrylate resins, and methacrylate-modified products thereof. The curing mode may be heat curing, ultraviolet curing, electron beam curing, or the like. Further, if necessary, other additives such as a coloring pigment, a flame retardant, an antioxidant, a lubricant, an antidust agent, and a curing accelerator may be blended.

Although the method for forming the insulating layer 14 is not particularly limited, the following method can be used when coating the plastic with an insulating resin. For example, a solution obtained by dissolving an insulating resin in a solvent is applied to gravure coating, kiss coating, die coating, blade coating, roll coating, knife coating, spray coating, bar coating, spin coating, and dip coating. Can be coated. The solvent can be appropriately selected depending on the type of resin used. For example, ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone, and alcohol solvents such as methanol, ethanol, propanol, ethylene glycol, glycerin and propylene glycol monomethyl ether can be used. Acids such as acetic acid, amide solvents such as formamide, dimethylacetamide and N-methylpyrrolidone, nitrile solvents such as acetonitrile and propylonitrile, and ester solvents such as methyl acetate and ethyl acetate can also be used. Carbonate-based solvents such as dimethyl carbonate and diethyl carbonate can also be used. During coating, a heating or drying step may be provided for volatilizing the solvent, if necessary. For heating and drying, a heating device and a drying device such as a hot air dryer and an infrared heater can be used, and the heating temperature, drying temperature, heating time and drying time can be appropriately selected.

The thickness of the insulating layer 14 in the Z direction is preferably 5 μm or more and 50 μm or less. When the thickness of the insulating layer 14 in the Z direction is 5 μm or more, sufficient strength can be ensured in the insulating layer 14 . When the thickness of the insulating layer 14 in the Z direction is 50 μm or less, slidability and flexibility are improved. From the above point of view, it is more preferable that the thickness of the insulating layer 251 in the Z direction is 10 μm or more and 30 μm or less. Moreover, the volume resistivity of the insulating layer 14 is preferably 10 ⁹ Ω·cm or more, more preferably 10 ¹³ Ω·cm or more.

Next, the insulating layer 16 will be described in detail.

The insulating resin used for the insulating layer 16 may be any resin having insulating properties, such as a thermosetting resin, an ultraviolet curable resin, or a coating agent made of a resin solution in which a cured film component is dispersed in a solvent. is mentioned. Thermosetting resins include phenol resins, acrylic resins, epoxy resins, polyamide resins, polyamide-imide resins, polyimide resins, melamine resins, silicone resins, and acrylic-modified silicone resins. Examples of UV-curable resins include epoxy acrylate resins, polyester acrylate resins, and methacrylate-modified products thereof. Examples of resin solutions include those obtained by dissolving polyester urethane resins and polyamideimide resins in organic solvents. In addition, if necessary, coloring pigments, flame retardants, antioxidants, lubricants, plasticizers, viscosity modifiers, anti-dust agents, curing accelerators, inorganic fillers such as silica and carbon black, silicone particles and polyester Organic fillers such as particles and other known additives may be blended. Among these, a coating agent composed of a resin solution in which a cured film component is dispersed in a solvent is preferable because the shrinkage caused by the curing reaction is small and warpage can be suppressed. Furthermore, a coating agent obtained by dissolving a polyamide-imide resin having flexibility and heat resistance in a solvent is more preferable.

A known method can be selected as a method for forming the insulating layer 16 . For example, methods such as bar coating, slit coating, spray coating, dot dispenser, and screen printing, in which a liquid resin composition is used as a coating film to form a cured film. Alternatively, a method of coating an adhesive component on a known plastic film and sticking the plastic film onto the conductive portion 15 via an adhesive component layer can be used. As a method for forming a cured film after coating film formation, a method such as heat curing, ultraviolet curing, electron beam curing, heat drying, and vacuum drying can be appropriately selected according to the material.

The thickness of insulating layer 16 is preferably greater than the thickness of conductive portion 15 in the Z direction from the viewpoint of preventing conductive portion 15 from coming into contact with members surrounding wiring board 200 . The thickness of the insulating layer 16 in the Z direction from the main surface 155 of the conductive portion 15 is preferably in the range of 2 μm or more and 10 μm or less. With a thickness of 2 μm or more, conductive portion 15 can be effectively prevented from coming into contact with members around wiring board 200 . Moreover, since the thickness in the Z direction from the main surface 155 of the conductive portion 15 of the insulating layer 16 is 10 μm or less, the flexibility of the wiring board 200 can be enhanced more effectively. From the above point of view, the thickness of the insulating layer 16 in the Z direction from the main surface 155 of the conductive portion 15 is more preferably 3 μm or more and 7 μm or less.

<Second embodiment>
Next, the wiring board 200 according to the second embodiment will be described with reference to FIG. Wiring board 200 according to the present embodiment differs from wiring board 200 according to the first embodiment in that openings 30 are provided in conductive layer 220 to form an opening pattern of a mesh structure.

The conductive portion 15 extends in a direction crossing the X direction in which the signal line 22 extends. The X direction is, for example, the first direction, and the direction crossing the X direction is, for example, the second direction.

The conductive part 15 is formed in a mesh structure, has a linear part 300 extending in the second direction, and is provided with the non-formation region 20, so that the flexibility is improved as compared with the first embodiment. obtain. In the present embodiment, the length L3 in the second direction from the connecting portion 17 to the open end 23 is λ ₁ /4±λ ₁ /8, and furthermore, if it is λ ₁ /4±λ ₁ /16 preferable. The second direction is not limited to the direction shown in FIG. 4, and may be any direction intersecting the X direction.

As in the first embodiment, the length from the connection portion 17 to the open end 24 may be λ ₁ /4±λ ₁ /8, and the length from the connection portion 17 to the open end 24, or the connection portion Either one of the lengths from 17 to the open end 23 should be λ ₁ /4±λ ₁ /8.

Although the case where the opening pattern of the conductive portion 15 has a mesh structure has been described here, any opening pattern can be employed.

<Third Embodiment>
Next, a wiring board 200 according to a third embodiment will be described with reference to FIGS. 5 and 6. FIG. FIG. 5 is a top view showing a modification of wiring board 200 according to the present embodiment, and FIG. 6 is a cross-sectional view of wiring board 200 taken along line DD in FIG.

This embodiment differs from the first embodiment in that the length from the connection portion 17 to the open end 23 is L1, and the length from the connection portion 17 to the open end 24 is L4, which is different from L1. is different.

It is preferable if the lengths L1 and L4 are λ ₁ /4±λ _1/8 , but noise can be suppressed if one of L1 or L4 is λ ₁ /4±λ _1/8 . . In this embodiment, the conductive portion 15 is provided with two patterns, but the number of patterns is not limited as long as L1 or L4 is λ ₁ /4±λ ₁ /8.

The length of the conductive layer 220 is the sum of the length L1 from the connecting portion 17 to the open end 23, the length L4 from the connecting portion 17 to the open end 24, and the diameter R of the connecting portion.

<Example>
Next, examples and comparative examples will be described. The flexible printed wiring board of the example corresponds to the wiring board 200 of the above embodiment. The flexible printed wiring board of the comparative example is a wiring board 200X. The flexible printed wiring boards of Examples and the flexible printed wiring boards of Comparative Examples are evaluated for flexibility and amount of radiation noise.

The measurement method is as follows. The surface resistivity was measured according to JIS K7194 using Loresta EP MCP-T360 (measuring probe MCP-TP03P) manufactured by Dia Instruments. Methods for evaluating flexible printed wiring boards according to examples and comparative examples will be described below.

(1) Radiation Noise Measurement The radiation noise amount of wiring board 200 was evaluated using a system having the configuration shown in FIG.

First, as a reference, a differential wiring board was prepared for measuring the radiation noise amount of the wiring board 200X without the conductive layer 220 . A copper foil having a thickness of 12 μm was laminated as a wiring layer on one side of a substrate of a polyimide film having a thickness of 25 μm (Kapton 100H manufactured by Toray DuPont Co., Ltd.). Thereafter, a differential transmission line having a line width of 140 μm, a line spacing of 55 μm, and a total length of 100 mm was fabricated by etching.

Next, this wiring board 200X was connected to the connection board 35. As shown in FIG. A signal generator 31 (M8041A manufactured by Keysight) was used to send a signal having a data pattern of PRBS23 with a bit rate of 5.3 Gbps. Then, the waveform of the common mode voltage is observed with an oscilloscope 32 (Agilent Technology). A reference differential wiring board without the layer 220 was obtained.

Next, this wiring board was connected to the connection board 35 . A signal generator 31 (M8041A manufactured by Keysight) was used to send a signal having a data pattern of PRBS23 with a bit rate of 5.3 Gbps. Then, the waveform of the common mode voltage was observed with an oscilloscope 32 (92504A manufactured by Agilent Technologies), and the input amplitude was adjusted so that the common mode voltage was 150 mV.

Next, the wiring boards 200 to be measured (of the examples and comparative examples) are connected to the connection board 35, and the signal generator 31 is used to send a data pattern with a bit rate of 5.3 Gbps as a PRBS23 signal. rice field. Here, a signal was sent with an input amplitude adjusted using a reference differential wiring board without the conductive layer 220 . Radiation noise of 5 GHz generated from the wiring board 200 was detected by a pen-shaped, 110 mm long near-field electric field probe 34 (made by Electrometric) and measured by a spectrum analyzer 33 (E4440A by Keysight). The amount of radiation noise was measured by setting the near electric field probe 34 at a point at a height of 5 mm from the wiring board 200 and scanning each point five times. After that, the area where the conductive layer 220 is formed was taken as the average value when all points were scanned with the near electric field probe 34 at intervals of 1 mm. The smaller the amount of radiation noise, the more the radiation noise can be suppressed, and the flexible printed wiring board has good shielding properties. The radiation noise was measured in an atmosphere with a temperature of 25° C. and a relative humidity of 23 to 50% in a frequency range of 300 kHz to 20 GHz. Evaluation criteria were as follows for the target frequencies shown in FIG. 13, and B or higher was considered acceptable.
A (excellent): less than 25 dBμV B (good): 25 dBμV or more, less than 40 dBμV C (improper): 40 dBμV or more

(2) Bending load Flexibility of each of the flexible printed wiring boards of the examples and the flexible printed wiring boards of the comparative examples was evaluated by the repulsive load when the flexible printed wiring boards of the comparative examples were bent.

FIG. 8 is a schematic diagram of an apparatus used to evaluate flexibility of wiring board 200 of Example and wiring board 200X of Comparative Example. A wiring board 200 of the embodiment has a wiring board body 210 and a conductive layer 220 . Wiring board 200X of the comparative example has wiring board main body 210 and conductive layer 220X.

As shown in FIG. 8, wiring boards 200 and 200X are arranged horizontally so that conductive layers 220 and 220X are inside. When one end of the wiring boards 200 and 200X in the longitudinal direction was bent 180 degrees with a curvature of 3 mm, the repulsive force in the vertical direction at one end was evaluated with a digital force gauge 43 of "ZTA-2N" manufactured by Imada Co., Ltd. .

The bending load is an index for quantitatively judging the flexibility of the flexible printed wiring board. In general, the greater the bending load of the flexible printed wiring board, the lower the flexibility of the flexible printed wiring board, that is, the harder and stiffer the flexible printed wiring board. Moreover, generally, the lower the flexibility of the flexible printed wiring board, the more difficult it becomes to attach the flexible printed wiring board to the rigid printed wiring board. Also, when a flexible printed wiring board is connected to two circuit boards (rigid printed wiring board), when one circuit board (rigid printed wiring board) is moved relative to the other circuit board, the movement is a factor that hinders The evaluation criteria were as follows.
A (excellent): bending load less than 14 gf B (good): bending load 14 gf or more, less than 17 gf C (improper): bending load 17 gf or more

(Example 1)
A wiring board 200 having the shape shown in FIG. 3 was produced. A 25 μm-thick polyimide film (Kapton 100H manufactured by DuPont-Toray Co., Ltd.) was prepared as the insulating layer 12 . A copper foil having a thickness of 12 μm is laminated on the surface of the insulating layer 12, and a signal line 22 having a line width of 50 μm, a line interval of 140 μm and a total length of 100 mm is formed by etching so as to sandwich the signal line 22 with a line width of 600 μm. Two ground lines 133 were produced at positions with an interval of 260 μm.

Next, an adhesive with a thickness of 25 μm as an insulating layer 14 and a coverlay with a thickness of 15 μm (CEAM0525KA manufactured by Arisawa Manufacturing Co., Ltd.) with a total thickness of 37.5 μm were pasted on the wiring layer to obtain a differential wiring board. rice field. Next, a conductive portion 15 is formed on the insulating layer 14 .

The conductive portion 15 is formed by applying a silver paste (product name: DD-1630L-245) manufactured by Kyoto Elex Co., Ltd. with a screen printer (manufactured by Micro Tech Co., Ltd.: MT-320T) to a thickness of 5 μm. It is formed by printing on the insulating layer 16 under such conditions. The conductive portion 15 is formed as shown in FIG. 3, and the end of the conductive portion 15 on the signal transmission side is electrically connected through a connection portion 17 in which a coverlay opening having a diameter of 0.8 mm is filled with a conductive paste. connected. Wiring board 200 of Example 1 was obtained, in which length L1 from connection portion 17 to non-formation region 20 was 12 mm, and length L2 of non-formation region 20 was 1 mm.

(Examples 2 to 5)
Wiring board 200 having the shape shown in FIGS. 4 and 9 to 11 was manufactured by the same manufacturing method as in Example 1. As Example 2, wiring board 200 in which conductive portion 15 has a mesh structure was produced. As Example 3, a wiring board 200 extending in the -X direction was manufactured as opposed to the wiring board 200 in Example 1 extending in the X direction. As Example 4, wiring board 200 in which connection portion 17 is arranged at the center of conductive layer 220 was manufactured. As Example 5, wiring board 200 was fabricated in which conductive layer 220 was arranged obliquely with respect to the X direction.

(Examples 6 to 12)
Compared to Example 1, the frequency f, the wavelength λ ₁ , the X-direction length of the conductive layer 220, the X-direction length L1 from the connecting portion 17 to the open end 23, and the X-direction length of the non-formation region 20 L2, was changed to the conditions described in FIG. Wiring boards 200 of Examples 6 to 12 were manufactured under the same conditions as in Example 1 except for the above conditions.

In Example 6, the X-direction length L1 from the connecting portion 17 to the open end 23 is alternately set to 12 mm and 26 mm, thereby suppressing noise in two frequency bands of 2.4 GHz and 5.3 GHz. can.

(Comparative example 1)
As shown in FIG. 12, a wiring board 200X was fabricated that differed from Example 1 only in that no non-formation region 20 was provided.

As shown in FIG. 13, all of the wiring boards 200 according to Examples 1 to 12 had a small amount of radiation noise at the target frequency, and the flexibility was good with B rank or higher.

On the other hand, in Comparative Example 1, since the non-formation region 20 was not provided, a noise suppression effect due to noise current reflection could not be obtained, and a sufficient noise suppression effect could not be exhibited. Moreover, when the wiring board 200X is bent, the conductive layer 220X is greatly distorted, and as a result, good flexibility cannot be obtained.

<Third Embodiment>
Next, with reference to FIG. 14, a digital camera 600, which is an imaging device, will be described as an example of the electronic device according to the embodiment.

A digital camera 600 is an interchangeable-lens digital camera and includes a camera body 601 . A camera body 601 is detachable with a lens unit (lens barrel) 602 including lenses. The camera body 601 includes a housing 611 , an electronic unit 100 and a wireless communication unit 150 . Electronic unit 100 and wireless communication unit 150 are housed inside housing 611 . The electronic unit 100 is an imaging unit in the case of an imaging device.

The electronic unit 100 includes a circuit board 101 , a circuit board 102 , and a wiring board 200 electrically connecting the circuit boards 101 and 102 . By using the wiring board 200 to connect the circuit board 101 and the circuit board 102, the wiring structure can be made lighter than the coaxial cable.

Circuit board 101 includes wiring board 110 and semiconductor device 111 mounted on wiring board 110 . Circuit board 102 includes wiring board 120 and semiconductor device 121 mounted on wiring board 120 . The semiconductor device 111 and the semiconductor device 121 are examples of electronic components mounted on the wiring boards 110 and 120 . The electronic components mounted on the wiring boards 110 and 120 can be imaging devices, arithmetic devices, display devices, communication devices, storage devices, power supply devices, and arithmetic devices. Electronic components mounted on wiring boards 110 and 120 are not limited to active components and may be passive components.

The semiconductor device 111 is an image sensor (imaging device) in this embodiment. The image sensor is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) image sensor. The image sensor has a function of converting light incident through the lens unit 602 into an electrical signal. The semiconductor device 111 can function as a device that outputs to the signal line 22 of the signal wavelength _λ1 .

The semiconductor device 121 is a processor (arithmetic device) such as a digital signal processor or an image signal processor in this embodiment. The image signal processor has a function of acquiring an electrical signal representing image data from the semiconductor device 111, which is an image sensor (imaging device), correcting the acquired electrical signal, and generating corrected image data. An article in which the circuit board 101 connected to the wiring board 200 in this way includes an image sensor can be called an imaging module or an imaging unit. The imaging module is an example of the electronic module 10 and the imaging unit is an example of the electronic unit 100 .

In this embodiment, the electronic unit 100 includes a driving device 160 that moves the circuit board 101 (wiring board 110 and semiconductor device 111). Drive device 160 includes a motor, which is an example of a drive source. In the digital camera 600 including the electronic unit 100 including the driving device 160, by moving the semiconductor device 111 via the circuit board 101, a camera shake correction (anti-vibration) function can be realized. The drive source in the drive device 160 is not limited to an electromagnetic motor, and may be a piezoelectric motor such as an ultrasonic motor, or an electrostatic motor. Since wiring board 200 is thus connected to circuit board 101 that is being moved, wiring board 200 is required to be flexible. Instead of the electronic unit 100 including the wiring board 200, the circuit boards 101, and 102, the electronic unit 100 includes either the circuit board 101 or the circuit board 102, and further includes the driving device 160 and other parts. The article may also be referred to as an electronic unit.

In this embodiment, wiring board 200 is mounted on digital camera 600 in a bent state, conductive layer 220 corresponds to the outside of the curved surface, and wiring board body 210 corresponds to the inside of the curved surface. That is, the conductive layer 220 corresponds to the surface on the housing 611 side, and the wiring board main body 210 corresponds to the surface opposite to the surface on the housing 611 side.

The wireless communication unit 150 performs wireless communication in the GHz band and is modularized. The wireless communication unit 150 has a rigid wiring board, which is an example of a wiring board 151 including an antenna (not shown), and a wireless communication IC 152 mounted on the wiring board 151 . The antenna is provided in the same plane as the wireless communication IC 152, and is arranged inside the housing 611 and close to the housing 611 so as to facilitate communication with the outside. The wireless communication IC 152 is preferably capable of transmitting and/or receiving image data by wirelessly communicating with an external device such as a PC or a wireless router via an antenna. In this embodiment, the wireless communication IC 152 can transmit and receive data via an antenna. Specifically, the wireless communication IC 152 modulates a digital signal representing image data acquired from the semiconductor device 121, and transmits the modulated signal from an antenna as a radio wave at a wireless standard communication frequency. Also, the wireless communication IC 152 demodulates radio waves received by the antenna into digital signals representing image data. The wireless communication IC 152 wirelessly communicates with external devices in compliance with standards such as Wi-Fi (registered trademark) and Bluetooth (registered trademark).

The frequency f is obtained by dividing the speed of light by the wavelength λ ₁ of the signal flowing through the signal line 22. If the frequency f of the digital signal flowing through the signal line 22 in the wiring board 200 is within the wifi communication band, radiation noise interference occurs. The wireless communication unit 150 outputs a signal of wavelength _λ2 , and the difference between the wavelength _λ2 and the value obtained by converting the wavelength _λ1 output from the signal line 22 into the wavelength in vacuum is close, for example, 5 mm or less. If there is, it is susceptible to noise interference radiated from the signal line 22 . As described above, due to the filtering effect of the distributed constant of the conductive portion 15 and the non-formation region 20 of the conductive layer 220 applied to the wiring board 200, the wavelength λ ₁ in vacuum is reduced to the common wavelength within the wiring board 200. It is the product of the square root of the effective dielectric constant for the mode current and the wavelength _λ1 . The effective dielectric constant in this embodiment is, for example, 1.3 or more and 1.7 or less.

In addition, if the frequency output from the wireless communication unit 150 differs from the frequency f flowing through the signal line 22 by 0.5 GHz or less, it is susceptible to noise interference radiated from the signal line 22 .

If the length L1 from the connecting part 17 to the open end 23 is λ/4±λ/8 or 5.8 mm or more and 23 mm or less, or 24 mm or more and 38.3 mm or less, noise in the frequency bands of 2 to 3 GHz and 5 to 6 GHz can be reduced. Note that frequency bands other than the frequency bands described above are not frequency bands that cause noise interference with the wireless communication unit 150 . Therefore, with wiring board 200 according to the present embodiment, noise does not affect wireless communication unit 150 in all frequency bands. Further, by using the conductive portion 15 provided on the wiring board 200 in the electronic unit 100 as the imaging unit as an electromagnetic shield, it is possible to suppress the electromagnetic waves emitted from the wireless communication unit 150 from generating noise in the electronic unit 100. . Wiring board 200 can also be used for connection between wiring board 151 and another wiring board.

The embodiments described above can be modified as appropriate without departing from the technical concept.

For example, multiple embodiments can be combined. Also, some items of at least one embodiment may be deleted or replaced.

Also, new additions may be made to at least one embodiment. It should be noted that the disclosure of this specification includes not only what is explicitly described in this specification, but also all matters that can be grasped from this specification and the drawings attached to this specification.

The disclosure herein also includes complements of the individual concepts described herein. That is, for example, if there is a statement to the effect that "A is greater than B" in the present specification, even if the statement to the effect that "A is not greater than B" is omitted, the present specification will still state that "A is It can be said that it discloses that it is not larger than B. This is because the statement "A is greater than B" presupposes consideration of the case "A is not greater than B."

REFERENCE SIGNS LIST 10 electronic module 15 conductive portion 17 connection portion 22 signal line 23 open end 111 electronic component 133 ground wire 200 flexible wiring board

Claims (21)

a flexible wiring board having a signal line, a conductive portion overlapping the signal line in a plan view, and a ground line; and an electronic component for passing a signal having a wavelength of λ when flowing through the signal line to the signal line. and an electronic module in which the flexible wiring board and the electronic component are connected,
The flexible wiring board includes a connecting portion that electrically connects the conductive portion and the ground line,
The conductive portion has an open end,
When the length in the direction in which the signal line extends from the connection portion to the open end is L, the relationship between the wavelength λ and the length L is λ/4−λ/8≦L≦λ/ An electronic module characterized in that it is 4+λ/8. 2. The electronic module according to claim 1, wherein the relationship between the wavelength λ and the length L is λ/4−λ/16≦L≦λ/4+λ/16. a flexible wiring board having a signal line extending in a first direction, a conductive portion overlapping the signal line in a plan view, and a ground line; An electronic module in which the flexible wiring board and the electronic component are connected,
The flexible wiring board includes a connecting portion that electrically connects the conductive portion and the ground line,
The conductive portion has a linear portion extending in a second direction intersecting the first direction,
The conductive portion has an open end,
When the length from the connecting portion to the open end in the second direction is L, the relationship between the wavelength λ and the length L is λ/4−λ/8≦L≦λ/4+λ/8. An electronic module characterized by: 4. The electronic module according to claim 3, wherein the relationship between the wavelength λ and the length L is λ/4−λ/16≦L≦λ/4+λ/16. A flexible wiring board having a signal line, a conductive portion overlapping the signal line in a plan view, and a ground line, and transmitting a signal having a wavelength λ output from an electronic component connected to the signal line,
The flexible wiring board includes a connecting portion that electrically connects the conductive portion and the ground line,
The conductive portion has an open end,
When the length in the direction in which the signal line extends from the connection portion to the open end is L, the relationship between the wavelength λ and the length L is λ/4−λ/8≦L≦λ/ A flexible wiring board characterized by being 4+λ/8. 6. The flexible wiring board according to claim 1, wherein the wavelength λ is 45 mm or more and 50 mm or less, or 100 mm or more and 105 mm or less. 6. A length in a direction in which the signal line extends from the open end to another open end adjacent to the open end is λ/500 or more and λ/5 or less. The flexible wiring board according to any one of 1. A flexible wiring board having a signal line, a conductive portion overlapping the signal line in plan view, and a ground line,
The flexible wiring board includes a connecting portion that electrically connects the conductive portion and the ground line,
The conductive portion has an open end,
The flexible wiring board, wherein the length of the conductive portion in the direction in which the signal line extends is longer than the interval between the conductive portion and another conductive portion adjacent to the conductive portion. A flexible wiring board having a signal line, a conductive portion overlapping the signal line in plan view, and a ground line,
The flexible wiring board includes a connecting portion that electrically connects the conductive portion and the ground line,
The conductive portion has an open end,
A flexible wiring board, wherein a length in a direction in which the signal line extends from the connecting portion to the open end is 5.8 mm or more and 23 mm or less, or 24 mm or more and 38.3 mm or less. 10. The length in the direction in which the signal line extends from the connection portion to the open end is longer than the interval between the conductive portion and another conductive portion adjacent to the conductive portion. The flexible wiring board according to item 1. 3. The length of the conductive portion in the direction in which the signal line extends is 2.4 times or more and 60 times or less than the distance between the conductive portion and another conductive portion adjacent to the conductive portion. 11. The flexible wiring board according to any one of 10. 12. The flexible wiring board according to claim 1, wherein the frequency of the current flowing through the signal line is 2 GHz or more and 3 GHz or less, or 5 GHz or more and 6 GHz or less. A length in a direction in which the signal line extends from the open end to another open end adjacent to the open end is 0.1 mm or more and 10 mm or less in the direction in which the signal line extends. The flexible wiring board according to any one of claims 1 to 12. A flexible wiring board according to any one of claims 1 to 13;
a rigid wiring board to which ends of the flexible wiring board are connected;
and an electronic component mounted on the rigid wiring board. 15. The electronic module of claim 14, wherein the electronic component comprises an image sensor. 16. The electronic module according to claim 14 or 15, wherein the signal lines include at least one set of differential signal wirings for transmitting differential signals. an electronic module according to any one of claims 14 to 16;
and a driving device for moving the rigid wiring board. an electronic module according to any one of claims 14 to 17;
a circuit board to which an end different from the end of the flexible wiring board is connected,
An electronic device, wherein a processor for processing signals output from the electronic component is mounted on the circuit board. an electronic module according to any one of claims 14 to 18;
a housing containing the electronic module,
The flexible wiring board is accommodated in the housing in a bent state,
The electronic device according to claim 1, wherein the conductive layer including the conductive portion is provided on an outer surface of the curved surfaces of the flexible wiring board. 20. The electronic device according to claim 19, wherein the wireless communication device capable of transmitting and receiving data to and from a device outside the housing, and the flexible wiring board are arranged inside the housing. . 21. The electronic device according to claim 20, wherein the difference between the frequency output by said wireless communication device and the frequency flowing through said signal line is 0.5 GHz or less.

Images