JP2010212438A - Circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board capable of controlling the characteristic impedance of signal wiring, suppressing an increase in a resistance value of a ground layer and also exhibiting countermeasures against high-frequency wave interference. <P>SOLUTION: The circuit board has strip structure or microstrip structure having a ground layer 6 and signal wiring 3a, 3b arranged on the ground layer via an insulator layer 2 wherein a conductive portion forming the ground layer is formed into a mesh-like conductor 6B having a large number of through holes at positions opposing the signal wiring, and the characteristic impedance of the signal wiring 3a, 3b is adjusted. A solid electrode region 6A where no through holes are formed is formed outside the mesh-like conductor 6B, thereby suppressing an increase in the DC resistance of the ground layer 6. When the thickness of the insulator layer 2 is t, a distance U between the signal wiring and the solid electrode region is set in a range of 20t≥U≥3t. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ground layer and a circuit board in which signal wiring is disposed with respect to the ground layer through an insulator layer.

For example, in a circuit board on which a device operating in a high frequency band is mounted, the characteristic impedance (hereinafter also referred to as Zo) of the signal transmission path is matched with the input / output impedance of the device in order to suppress the signal reflection and waveform distortion. It is necessary to let
In order to match the characteristic impedance of the signal transmission path described above, a strip structure or a microstrip structure in which a ground layer is opposed to a signal transmission path (strip line) having an appropriate pattern width with an insulating layer having an appropriate thickness interposed therebetween is used. It has been adopted.

The ground layer in the circuit board structure described above serves as an electrical reference plane that defines the characteristic impedance of the signal transmission path. In general, the characteristic impedance is often selected to be around 50Ω for single end and around 100Ω for differential transmission.
On the other hand, the characteristic impedance of the circuit board is the ratio of the reactance L per unit length of the signal transmission path and the capacitance C per unit area between the signal transmission path and the ground layer (reactance L / static It is a value approximated by the square root of the capacitance C).

By the way, in recent years, thin rigid boards and flexible circuit boards are frequently used as circuit boards for mounting the above-described devices. When such circuit boards are adopted, of course, signal transmission paths for the ground layer are naturally used. The interlayer is narrow (thin), and the value of the capacitance C between them increases almost in inverse proportion to the dimension between the layers.
Therefore, in order to obtain the desired Zo in the above-described thin multilayer circuit board, the width of the signal transmission path (hereinafter also referred to as signal wiring) is larger than that of a conventional circuit board having a thick interlayer. By forming it narrow (narrow), means for suppressing the increase in the capacitance C must be employed.

  Thus, in order to obtain a desired Zo, when the signal wiring is to be formed thin, there is a case where the signal wiring has to be thinned so that the processing of the signal wiring is difficult. Even if signal wiring can be processed, the thinner the signal wiring, the higher the ratio of circuit processing accuracy and line width variation, and the Zo variation increases accordingly.

  For this reason, there arises a problem that signal reflection and waveform distortion occur in the signal wiring portion where the change of Zo is large. Furthermore, since the wiring resistance value of the signal wiring is increased, there is a problem that the higher the signal frequency supplied to the signal wiring, the worse the transmission characteristics.

  Therefore, in order to solve the above-described technical problem, the ground layer formed as a so-called solid electrode layer is removed in a mesh shape so that the opposing area between the ground layer and the signal wiring per unit area is substantially reduced. Proposals have been made to ensure the width of the signal wiring by making it smaller. This is disclosed in the following prior art documents.

JP 7-32463 A

  FIG. 7 shows a configuration example of the circuit board shown in the above-described prior art document, and shows an example in which the direction of the signal wiring is bent about 45 degrees in the middle. That is, FIG. 7 shows a state in which, for example, signal wirings 3a and 3b for performing differential transmission arranged in parallel to each other are superimposed on a mesh pattern in which parallelogram-shaped openings are regularly formed in the ground layer 6. It is shown in a state seen through from a direction orthogonal to the circuit board surface.

In the example shown in FIG. 7, a large number of parallelogram (diamond) meshes are opened in the ground layer 6 by lines intersecting in two directions. Then, the crossing angle of the lines in the two directions on the ground layer 6 side with respect to the signal wirings 3a and 3b in the lower half part of the diagram indicated by the symbol A and the ground layer for the signal wirings 3a and 3b in the upper half portion of the diagram indicated by the symbol B The crossing angles of the two-direction lines on the 6 side are configured to be substantially the same.
Thereby, it is possible to prevent the characteristic impedance of the signal wirings 3a and 3b bent in the middle from changing greatly in the regions A and B.

By the way, when the opening is formed on the entire surface of the ground layer as described above and the characteristic impedance of the signal wiring opposed thereto is adjusted, the conductor is applied to the entire surface of the ground layer (solid electrode). In comparison, the DC resistance value of the ground layer increases.
For this reason, for example, a part of the ground layer away from the earth point is excited by receiving a high-frequency signal, the signal wiring is subject to spurious interference due to the high-frequency signal, or the leakage of the high-frequency signal flowing through the signal wiring becomes severe. Invite problems.

  The present invention has been made by paying attention to the technical problems described above, and can sufficiently control the characteristic impedance of the signal wiring and suppress the increase in the resistance value of the ground layer. It is an object of the present invention to provide a circuit board that can sufficiently exhibit countermeasures such as spurious interference.

  The circuit board according to the present invention, which has been made to solve the above-described problems, includes a ground layer and a signal wiring disposed through an insulator layer with respect to the ground layer, and capacitive coupling between the ground layer and the signal wiring. Is a circuit board in which the characteristic impedance of the signal wiring is controlled, and the conductive portion forming the ground layer is provided with a number of holes at positions facing the signal wiring. By arranging the mesh-like conductor part, it is configured to control the capacitive coupling between the ground layer and the signal wiring, and a solid electrode region not formed with a hole is formed outside the mesh-like conductor part. It is characterized by being.

  In this case, it is desirable that the distance U between the signal wiring and the solid electrode region is set in a range of 20t ≧ U ≧ 3t, where t is the thickness of the insulator layer. This effect can be exhibited remarkably in a thin circuit board in which the insulator layer has a thickness of 100 μm or less.

  The plurality of holes formed in the mesh-like conductor portion are formed in a shape in which a plurality of lines in two directions intersect to form a parallelogram opening.

  Moreover, in one preferable embodiment for realizing the circuit board, the insulator layer is configured such that the signal wiring is laminated on one surface and the ground layer is disposed on the other surface.

  In another preferred embodiment, the signal wiring is formed on the insulator layer, and the ground layer is stacked via a second insulator layer covering the signal wiring on the insulator layer. To be.

Furthermore, in another preferred embodiment, the insulator layer has the signal wiring laminated on one surface, the ground layer is disposed on the other surface, and the signal wiring on the insulator layer is arranged. The second ground layer is stacked via the covering second insulator layer.
The insulator layer is preferably configured using a film-like base substrate.

According to the circuit board described above, the conductive portion constituting the ground layer at the position facing the signal wiring is formed into a mesh-shaped conductor portion in which a large number of holes are formed, so that the signal wiring facing the signal wiring The characteristic impedance can be adjusted.
And since the said conductive part in the position away from the said signal wiring is made into the solid electrode area | region where a punch hole is not formed, this solid electrode suppresses the raise of the direct current | flow resistance of a ground layer, and measures, such as the above-mentioned spurious interference, are effective. It is possible to demonstrate it.

  In this case, the thickness t of the insulator layer separating the signal wiring and the ground layer dominates the degree of capacitive coupling between them, and when the thickness t of the insulator layer is used as a parameter, the signal wiring Is set to a range of 20t ≧ U ≧ 3t, thereby satisfying the condition for adjusting the characteristic impedance of the signal wiring and securing a low DC resistance value as a ground layer. To be.

  The above range can be applied to a circuit board that is thinly formed as a whole with the thickness t of the insulator layer separating the signal wiring and the ground layer being 100 μm or less, whereby a more preferable result can be obtained.

  As the insulator layer, a circuit board having excellent flexibility can be obtained by using a film-like base substrate. When, for example, polyimide is used for the base substrate, heat resistance and mechanical properties are also excellent. A flexible circuit board can be provided.

1 is a laminated structure diagram of a circuit board showing a first embodiment according to the present invention. FIG. FIG. 2 is a perspective view showing a configuration of a part of a ground layer and signal wiring used in the circuit board shown in FIG. 1. It is sectional drawing explaining the relationship between the signal wiring which interposed the insulator layer, and the ground layer. It is the diagram which showed the relationship of the impedance of the track | line with respect to the distance of a signal wiring and a solid electrode. FIG. 3 is a laminated structure diagram of a circuit board showing a second embodiment according to the present invention that adopts the configuration of the ground layer shown in FIG. It is the laminated structure figure of the circuit board which similarly showed 3rd Embodiment. It is the perspective view which showed the structure of a part of ground layer and signal wiring in the conventional circuit board.

Hereinafter, a circuit board according to the present invention will be described based on the embodiments shown in the drawings. FIG. 1 shows a laminated structure of a circuit board showing the first embodiment.
A circuit board 1 shown in FIG. 1 constitutes a microstrip structure in which a signal wiring is arranged with respect to a ground layer and an insulating layer with respect to the ground layer. In this embodiment, the insulating layer As shown, a film-like base substrate 2 is employed.

For example, signal wirings 3a and 3b for differential transmission are formed on one surface (upper side in FIG. 1) of the base substrate 2, and the upper surfaces (upper side in FIG. 1) of the signal wirings 3a and 3b are formed. An insulating layer 4a functioning as a second insulator layer is stacked. A first covering layer 5a is provided on the upper surface of the insulating layer 4a.
On the other hand, a ground layer 6 is formed on the other surface (lower side in FIG. 1) of the base substrate 2, and an insulating layer 4b functioning as a third insulator layer is formed on the lower surface of the ground layer 6, Further, a second coating layer 5b is formed on the lower surface.

  The base substrate 2 that functions as a central insulator layer constituting the microstrip structure also has a function as a core of the circuit board 1. Examples of the material of the base substrate 2 include a resin film and a fiber substrate.

Examples of the material constituting the resin film include polyimide resins such as polyimide resins, polyamide resins, and polyamideimide resins, thermosetting resins such as epoxy resins, and thermoplastic resins such as liquid crystal polymers.
Among these, a polyimide resin or a liquid crystal polymer is preferable. For example, in the case of polyimide resin, it is excellent in heat resistance and mechanical properties and is easy to obtain. In the case of a liquid crystal polymer, it is suitable for high-speed signal transmission due to its low relative dielectric constant, and it has excellent dimensional stability due to its low hygroscopicity.

  Examples of the fiber base material used for the insulating layer include glass fiber base materials such as glass fiber cloth and glass non-fiber cloth, or inorganic fiber base materials such as fiber cloth and non-fiber cloth containing inorganic compounds other than glass, aromatic And organic fiber base materials composed of organic fibers such as aromatic polyamide resins, polyamide resins, aromatic polyester resins, polyester resins, polyimide resins, and fluororesins. Among these base materials, glass fiber base materials represented by glass fiber fabric are preferable in terms of strength and water absorption.

  When a fiber base material is used for the insulator layer, the fiber base material is preferably used in a state of being impregnated with a resin. As the resin impregnated in the fiber base material, a thermosetting resin such as an epoxy resin or an acrylic resin is preferably used, and among these, an epoxy resin is preferable from the viewpoint of heat resistance.

The thickness of the base substrate 2 is preferably in the range of 1 to 100 μm, more preferably in the range of 5 to 50 μm, and more preferably in the range of 10 to 30 μm.
By setting the thickness of the base substrate 2 to be equal to or greater than the lower limit value, it becomes easy to make the signal line width equal to or greater than the processing limit. On the other hand, by setting the thickness to be equal to or less than the upper limit value, rigidity is high. It is possible to suppress the occurrence of excessive thickness and retain the characteristics of a thin substrate such as a flexible circuit board that is flexible.

  The signal wirings 3a and 3b arranged on one surface of the base substrate 2 may be directly provided on the base substrate 2, or may be provided via an adhesive. Then, at the end portion of each signal wiring or an appropriate intermediate portion, it is bonded to a mounting pad such as a semiconductor device (not shown) and functions as the circuit board 1.

Examples of the insulating layer 4a covering the signal wirings 3a and 3b include acrylic resin, epoxy resin, polyimide resin, and liquid crystal polymer. Among these, an epoxy resin is preferable. Thereby, heat resistance and flexibility can be improved.
On the other hand, when the liquid crystal polymer is used, it is possible to take advantage of the characteristics of a low relative dielectric constant and excellent high-speed signal transmission characteristics.

  The thickness of the insulating layer 4a is not particularly limited, but is preferably 5 to 40 μm, and particularly preferably 10 to 30 μm. By making the thickness of the insulating layer 4a equal to or higher than the lower limit value, it is possible to suppress a decrease in circuit embeddability, and by setting the thickness to be equal to or lower than the upper limit value, it is possible to suppress an increase in the amount of spots of the insulating layer 4a Reliability can be maintained.

The first covering layer 5a laminated on the upper surface of the insulating layer 4a is preferably made of a resin material. Examples of the resin material include polyester resins, polyimides, and liquid crystal polymers. Among these, polyimide is preferable. Thereby, heat resistance and flexibility can be improved.
Although the thickness of the said coating layer 5a is not specifically limited, It is preferable that it is 5-50 micrometers, and 10-30 micrometers is especially preferable. By making the thickness of the coating layer 5a equal to or greater than the lower limit value, it becomes easy to maintain the strength of the resin layer within a practical range, and by making the thickness less than the upper limit value, slidability and flexibility are maximized. It becomes easy to make it.

The insulating layer 4a may be formed integrally with the first coating layer 5a as an adhesive layer of the first coating layer 5a.
In this case, the first coating layer 5a is composed of a resin layer and an adhesive layer. In this case, as the resin material constituting the resin layer, for example, a polyester resin, polyimide, liquid crystal polymer, or the like is used similarly to the resin material constituting the first covering layer 5a. Among these, it is preferable to use polyimide. Thereby, heat resistance and flexibility can be improved.

  In this case, the material constituting the adhesive layer is, for example, an acrylic resin, an epoxy resin, or a polyimide resin, like the material constituting the insulating layer 4a functioning as the second insulator layer described above. Etc. can be used. Among these, an epoxy resin is preferable, and thereby heat resistance and flexibility can be improved.

  The conductive portion as the ground layer 6 disposed on the other surface (back surface) of the base substrate 2 is made of a conductor made of a copper material, and the conductive portion is located at a position facing the signal wirings 3a and 3b. A number of holes formed in the parallelogram openings are formed. The specific configuration of the ground layer 6 will be described later in detail with reference to FIG.

On the lower surface of the ground layer 6 (the lower side in FIG. 1), an insulating layer 4b as a third insulator layer is provided. Examples of the material constituting the insulating layer 4b include acrylic resins, epoxy resins, and polyimide resins. Among these, an epoxy resin is preferable. Thereby, heat resistance and flexibility can be improved.
In addition, the material which comprises the insulating layer 4a which comprises the above-mentioned 2nd insulator layer, and the insulating layer 4b which comprises a 3rd insulator layer may be the same, or may differ.

The thickness of the insulating layer 4b is not particularly limited, but is preferably 5 to 40 μm, and particularly preferably 10 to 30 μm.
Similar to the insulating layer 4a already described, the thickness of the insulating layer 4b is set to be equal to or higher than the lower limit value, thereby suppressing deterioration of the embedding property of the circuit. An increase in the amount of protrusion can be suppressed, and the reliability of interlayer adhesion can be maintained.
Moreover, the thickness of the insulating layer 4a constituting the second insulator layer and the thickness of the insulating layer 4b constituting the third insulator layer may be the same or different.

The second coating layer 5b provided on the lower surface of the insulating layer 4b is preferably made of a resin material. Examples of the resin material include polyester resin, polyimide, liquid crystal polymer, and the like. Among these, polyimide is preferable. Thereby, heat resistance and flexibility can be improved.
Further, the resin material constituting the first coating layer 5a and the resin material constituting the second coating layer 5b may be the same or different.

  The thickness of the second coating layer 5b is not particularly limited, but is preferably 5 to 50 μm, and particularly preferably 10 to 30 μm. As with the coating layer 5a already described, this makes it easy to maintain the strength of the resin layer within the practical range by setting the thickness of the coating layer 5b to be equal to or higher than the lower limit, and to be lower than the upper limit. This makes it easy to maximize slidability and flexibility.

The insulating layer 4b may be formed integrally with the coating layer 5b as an adhesive layer for the second coating layer 5b. In this case, the second coating layer 5b is composed of a resin layer and an adhesive layer.
In this case, examples of the material constituting the resin layer include a polyester-based resin, a polyimide, a liquid crystal polymer, and the like, similarly to the resin material constituting the second coating layer 5b described above. Among these, polyimide is preferable, and heat resistance and flexibility can be improved by employing this.

  Further, in this case, as the material constituting the adhesive layer, for example, an acrylic resin, an epoxy resin, a polyimide resin, and the like can be cited as with the material constituting the second insulating layer 4b described above. . Among these, epoxy resins are preferable, and heat resistance and flexibility can be improved by adopting them.

FIG. 2 is a partially enlarged view of the configuration of the ground layer 6 described above. 2 shows a state in which the signal wirings 3a and 3b described above are superimposed on the ground layer 6 through the base substrate 2 in a state seen through from a direction orthogonal to the surface.
As described above, the ground layer 6 is made of a conductor made of a copper material, and the position of the conductor facing the signal wirings 3a and 3b constitutes a mesh-like conductor portion 6B in which a large number of holes are formed. Yes.

That is, the hole in this embodiment is formed as a parallelogram (diamond) opening by intersecting a plurality of lines in two directions. The plurality of lines in the two directions are preferably inclined with respect to the signal wirings 3a and 3b within a range of 5 to 40 degrees. In addition, the longer diagonal line of the rhomboid opening has a mesh pattern that matches the wiring direction of the signal wirings 3a and 3b.
Thereby, it is possible to prevent the characteristic impedance of the signal wirings 3a and 3b bent about 45 degrees in the middle as shown in FIG.

  Each of the openings described above may have different sizes (opening areas), but preferably, the openings A have the same size in the regions A and B. Thereby, the characteristic impedance of the signal wirings 3a and 3b can be controlled with high accuracy.

On the other hand, on the outside of the mesh-like conductor portion 6B facing the signal wirings 3a and 3b, a solid electrode region 6A made of a copper material without a hole is formed.
That is, the outside of the mesh-like conductor portion 6B that greatly affects the control of the characteristic impedance of the signal wirings 3a and 3b is formed as a solid electrode region 6A.

The relationship between the mesh-like conductor portion 6B facing the signal wirings 3a and 3b through the insulator layer made of the film-like base substrate 2 and the solid electrode region 6A formed outside the mesh-like conductor portion 6B is shown. 3 is a schematic cross-sectional view.
In this embodiment, the thickness t of the insulator layer 2 is 100 μm or less, and the entire laminated structure is applied to a very thin circuit board. Therefore, the signal wirings 3a and 3b and the solid electrode region are applied. The distance U from 6A dominates the degree of capacitive coupling between the two.

  In this case, when the thickness t of the insulator layer 2 is used as a parameter, the distance U between the signal wirings 3a and 3b and the solid electrode region 6A is in the range of 20t ≧ U ≧ 3t, more preferably 10t ≧ U. It is desirable to set the range of ≧ 3t.

FIG. 4 shows a characteristic example in which the distance U (multiple of the interlayer thickness t) between the signal wirings 3a and 3b and the solid electrode region 6A is shown on the horizontal axis, and the characteristic impedance Zo of the signal wirings 3a and 3b is shown on the vertical axis. Is.
In the characteristic example shown in FIG. 4, each of the differential signal lines 3a and 3b has a line width L / interline distance S = 100 μm / 100 μm, an interlayer thickness t = 25 μm, and a copper (conductor) remaining rate of the mesh-like conductor portion 6B. = In the case of 30%.

That is, as shown in the characteristic diagram of FIG. 4, when the distance U between the signal wirings 3a and 3b and the solid electrode region 6A is less than 3t, the capacitive coupling of the solid electrode region to the signal wiring is reduced. It increases rapidly, and proper impedance control of the signal wiring by the mesh-like conductor portion 6B becomes impossible.
On the other hand, when the distance U between the signal wirings 3a and 3b and the solid electrode region 6A exceeds 3t, the capacitive coupling of the solid electrode region to the signal wiring is drastically reduced, and the impedance of the signal wiring by the mesh-like conductor portion 6B. The accuracy of control can be improved.

  Although the same measurement was attempted under the condition of the interlayer thickness t = 100 μm or less, when the distance U between the signal wirings 3a and 3b and the solid electrode region 6A is less than 3t, the solid electrode for the signal wiring It has been verified that the capacitive coupling of the region rapidly increases and the characteristic impedance of the signal wiring decreases, and it is recognized that the results are almost the same as those shown in FIG.

By the way, the larger the value of the distance U, the smaller the influence of the solid electrode region 6A, but the increase of the DC resistance value of the ground layer accompanying the increase of the area of the mesh-like conductor portion 6B The high frequency characteristics of the substrate will be deteriorated.
Therefore, in order to cope with an increase in the DC resistance value of the ground layer, the distance U between the signal wirings 3a and 3b and the solid electrode region 6A is desirably 20 t or less, and more desirably 10 t or less. The

  Thus, by setting the distance U between the signal wirings 3a and 3b and the solid electrode region 6A within the above-described range, the characteristic impedance of the signal wirings 3a and 3b can be adjusted, and the ground layer 6 can have a low value. The condition for securing the DC resistance value is satisfied.

  FIG. 5 shows a laminated structure of a circuit board according to the second embodiment of the present invention. In FIG. 5, parts that perform the same functions as those shown in FIG. 1 already described are denoted by the same reference numerals, and therefore detailed description thereof will be omitted as appropriate.

  In the configuration shown in FIG. 5, the signal wirings 3a and 3b are configured on a film-like base substrate 2 and function as an insulator layer covering the signal wirings 3a and 3b on the base substrate 2. A ground layer 6 is laminated on the upper surface of the second insulating layer 4a, thereby forming a microstrip structure.

  In the stacked configuration shown in FIG. 5, the ground layer 6 is configured to face the signal wirings 3a and 3b through the insulating layer 4a as compared with the stacked configuration shown in FIG. Also in this configuration, the same effect can be obtained by adopting the configuration of the ground layer 6 shown in FIG.

  FIG. 6 shows a laminated structure of a circuit board according to the third embodiment of the present invention. Also in FIG. 6, parts that perform the same functions as those shown in FIG. 1 already described are denoted by the same reference numerals, and therefore detailed description thereof is omitted.

  In the configuration shown in FIG. 6, signal wirings 3 a and 3 b are laminated on one surface of a film-like base substrate 2 that functions as an insulator layer, and a first ground layer 6 a is disposed on the other surface of the base substrate 2. In addition, a second ground layer 6b is laminated via a second insulator layer 4a covering the signal wirings 3a and 3b on the base substrate. Thus, a strip structure is configured.

In the laminated structure shown in FIG. 6, in comparison with the laminated structure shown in FIG. 1, the two ground layers 6a and 6b each have a signal via the film-like base material 2 and the insulating layer 4a that function as insulator layers. It is configured to face the wiring 3.
By adopting the configuration of the ground layer shown in FIG. 2 in each of the ground layers 6a and 6b in this configuration, the same operational effects can be obtained.

  In addition, although the mesh-shaped conductor part 6B in embodiment described above is made into the structure which arranged many rhombus opening as shown in FIG. 2, this opening is not restricted to the above-mentioned specific shape. For example, it can also be formed by arranging circular or other openings.

  In the above-described embodiment, the ground layer may be configured to be applied with a circuit reference potential, or the operation power supply of each device may be superimposed. Therefore, the potential applied to the ground layer is not particularly limited.

  The circuit board according to the present invention can be used for a printed wiring board, a flexible printed wiring board, a multilayer flexible printed wiring board, and the like, and can be suitably used particularly for a circuit board on which a device operating in a high frequency band is mounted.

1 Circuit board 2 Base substrate (insulator layer)
3a, 3b Signal wiring 4a, 4b Insulating layer 5a, 5b Cover layer 6, 6a, 6b Ground layer 6A Solid electrode region 6B Mesh conductor

Claims (8)

The signal wiring is disposed via the insulator layer with respect to the ground layer and the ground layer, and the characteristic coupling of the signal wiring is controlled by controlling the capacitive coupling between the ground layer and the signal wiring. A circuit board,
The conductive portion forming the ground layer is provided with a mesh-like conductor portion provided with a large number of holes at positions facing the signal wiring, thereby controlling capacitive coupling between the ground layer and the signal wiring. Configured as
The circuit board is characterized in that a solid electrode region not formed with a hole is formed outside the mesh-like conductor portion.   The distance U between the signal wiring and the solid electrode region is set in a range of 20t ≧ U ≧ 3t, where t is the thickness of the insulator layer. Circuit board.   The circuit board according to claim 2, wherein the insulator layer has a thickness of 100 μm or less.   4. The plurality of holes formed in the mesh-shaped conductor portion are formed into parallelogram openings by intersecting a plurality of lines in two directions. 1. The circuit board described in item 1.   4. The circuit according to claim 1, wherein the insulator layer is formed by laminating the signal wiring on one surface and arranging the ground layer on the other surface. 5. substrate.   The said signal wiring is comprised on the said insulator layer, The said ground layer is laminated | stacked through the 2nd insulator layer which covers the signal wiring on the said insulator layer. 4. The circuit board according to any one of 3 above.   The insulator layer is formed by laminating the signal wiring on one surface, arranging the ground layer on the other surface, and secondly via a second insulator layer covering the signal wiring on the insulator layer. The circuit board according to any one of claims 1 to 3, wherein a ground layer is laminated.   The circuit board according to claim 1, wherein the insulator layer is formed of a film-like base substrate.

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