High Frequency Circuits

Abstract

This high frequency circuit is provided with a first dielectric layer, a circuit layer which is provided on the first dielectric layer and which includes a high frequency signal transmission path and a ground pattern disposed around the transmission path, a second dielectric layer provided in such a way that the circuit layer is positioned between the first dielectric layer and the second dielectric layer, a first electrical conductor layer provided in such a way that the first dielectric layer is positioned between the circuit layer and the first electrical conductor layer, a second electrical conductor layer provided in such a way that the second dielectric layer is positioned between the circuit layer and the second electrical conductor layer, and an electromagnetic wave shield provided around the transmission path, wherein: the electromagnetic wave shield is configured by providing ground electrical conductors on the inner surfaces of a plurality of holes which penetrate through the first dielectric layer, the ground pattern, the second dielectric layer, the first electrical conductor layer, and the second electrical conductor layer; the plurality of holes are a plurality of elongated holes provided spaced apart in the direction surrounding the transmission path; and in each of the plurality of elongated holes, the longitudinal dimension in the direction surrounding the transmission path is greater than the width dimension.

Description

[Technical field]

[0001] The present disclosure relates to high frequency circuits. This application claims priority based on Japanese Patent Application No. 2020-084545 filed on May 13, 2020, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0002] Patent Document 1 discloses a structure having a large number of shielded vias electrically connected to a front surface ground and a back surface ground of a dielectric substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-274513 Summary of the Invention

[0004] An aspect of the present disclosure is a high-frequency circuit. The high-frequency circuit of the present disclosure includes a first dielectric layer, a circuit layer provided on the first dielectric layer and including a transmission path for a high-frequency signal and a ground pattern arranged around the transmission path, a second dielectric layer provided so that the circuit layer is located between the first dielectric layer, a first conductor layer provided so that the first dielectric layer is located between the circuit layer, a second conductor layer provided so that the second dielectric layer is located between the circuit layer, and an electromagnetic wave shield provided around the transmission path, the electromagnetic wave shield being configured to include ground conductors on inner surfaces of a plurality of holes penetrating the first dielectric layer, the ground pattern, the second dielectric layer, the first conductor layer, and the second conductor layer, the plurality of holes being a plurality of long holes provided at intervals along a direction surrounding the transmission path, and each of the plurality of long holes has a longitudinal dimension along the direction surrounding the transmission path that is greater than a width dimension. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a plan view of a high-frequency circuit according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line BB of FIG. [Diagram 3] FIG. 3 is an exploded perspective view of the first conductive layer, the circuit layer, and the second conductive layer. [Figure 4] FIG. 4 is a diagram showing the first half of the manufacturing process for the high-frequency circuit according to the embodiment. [Diagram 5] FIG. 5 is a diagram showing the latter half of the manufacturing process for the high-frequency circuit according to the embodiment. [Figure 6] FIG. 6 is a plan view showing a modified example of the high-frequency circuit. [Figure 7] FIG. 7 is a plan view of a high-frequency circuit according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] [Problem that this disclosure aims to solve] The shield via is formed by forming a large number of through holes, which are circular in plan view and penetrate the dielectric substrate in the thickness direction, in the dielectric substrate, and providing a conductor such as copper in the through holes. The shield via is used as an electromagnetic wave shield to prevent leakage of electromagnetic waves in the dielectric substrate.

[0007] 7 shows an example of a structure in which a large number of shield vias 102 are formed to surround a signal transmission line 101 in a high-frequency circuit 100 having the signal transmission line 101. Unwanted electromagnetic waves are emitted from the high-frequency signal transmission line 101. The electromagnetic waves become noise for the surrounding circuits and deteriorate the characteristics of the surrounding circuits.

[0008] When a large number of shield vias 102 are provided around the signal transmission line 101, the large number of shield vias 102 function as an electromagnetic wave shield. This electromagnetic wave shield can block electromagnetic waves leaking from the signal transmission line 101.

[0009] However, there is a risk of electromagnetic wave leakage from between the shield vias 102. In order to more reliably prevent electromagnetic wave leakage, it is conceivable to arrange multiple rows of shield vias 102 in parallel around the signal transmission line 101, as shown in Fig. 7. In this case, a problem occurs in that the number of shield vias 102 becomes very large. If the number of shield vias 102 becomes large, a large number of holes for the shield vias 102 must be formed, which reduces the manufacturing efficiency of the circuit.

[0010] On the other hand, if the number of shield vias 102 is reduced from the viewpoint of circuit manufacturing efficiency, electromagnetic waves will be more likely to leak from between the shield vias 102, and the electromagnetic wave shielding properties will be impaired.

[0011] Therefore, it is desirable to efficiently prevent leakage of electromagnetic waves.

[0012] [Effects of this disclosure] According to the present disclosure, leakage of electromagnetic waves can be efficiently prevented.

[0013] [1. Description of the embodiment of the present disclosure]

[0014] (1) A high-frequency circuit according to an embodiment includes a first dielectric layer, a circuit layer provided on the first dielectric layer and including a transmission path for a high-frequency signal and a ground pattern arranged around the transmission path, a second dielectric layer provided so that the circuit layer is located between the first dielectric layer, a first conductor layer provided so that the first dielectric layer is located between the circuit layer, a second conductor layer provided so that the second dielectric layer is located between the circuit layer, and an electromagnetic wave shield provided around the transmission path. Since the circuit layer is sandwiched between the first conductor layer and the second conductor layer, leakage of electromagnetic waves from the transmission path in the thickness direction of the high-frequency circuit is prevented. The electromagnetic wave shield is configured to include a ground conductor on the inner surface of a plurality of holes penetrating the first dielectric layer, the ground pattern, the second dielectric layer, the first conductor layer, and the second conductor layer. The plurality of holes are elongated holes provided at intervals along a direction surrounding the transmission line, and each of the plurality of elongated holes has a longitudinal dimension along the direction surrounding the transmission line that is greater than its width. Since the holes in which the electromagnetic wave shield is formed are elongated along the direction surrounding the transmission line, leakage of electromagnetic waves can be efficiently prevented even if the number of holes is reduced compared to the case where a circular shield via is provided.

[0015] (2) The longitudinal dimension is preferably more than five times the width dimension. By making the longitudinal dimension of the hole more than five times the width dimension of the hole, the hole becomes sufficiently long and can efficiently prevent leakage of electromagnetic waves.

[0016] (3) The longitudinal dimension is preferably greater than the interval. By making the longitudinal dimension of the hole greater than the interval between the holes, leakage of electromagnetic waves can be efficiently prevented.

[0017] (4) The longitudinal dimension is preferably greater than five times the interval. By making the longitudinal dimension of the hole greater than five times the interval between the holes, leakage of electromagnetic waves can be efficiently prevented.

[0018] (5) It is preferable that each of the plurality of holes continuously penetrates the first dielectric layer, the ground pattern, the second dielectric layer, the first conductive layer, and the second conductive layer. Continuously penetrating holes can more reliably prevent leakage of electromagnetic waves.

[0019] (6) The electromagnetic wave shield includes at least a first shield provided around the transmission line and a second shield provided on an outer periphery of the first shield, the first shield being configured to include the ground conductor on an inner surface of a plurality of first holes penetrating the first dielectric layer, the ground pattern, the second dielectric layer, the first conductor layer, and the second conductor layer, the plurality of first holes being a plurality of first elongated holes provided at intervals along a direction surrounding the transmission line, and each of the plurality of first elongated holes has a longitudinal dimension along the direction surrounding the transmission line that is larger than a width dimension. Preferably, the second shield is configured to include the ground conductor on the inner surfaces of the first dielectric layer, the ground pattern, the second dielectric layer, the first conductor layer, and the second conductor layer on the outer circumferential side of the first holes, the second holes being second elongated holes spaced apart along a direction surrounding the transmission line, each of the second elongated holes having a longitudinal dimension greater than a width dimension along the direction surrounding the transmission line, and the second shield is disposed to block electromagnetic waves leaking from between the first elongated holes. In this case, leakage of electromagnetic waves can be more efficiently prevented.

[0020] (7) It is preferable that the high-frequency circuit further includes a cover film attached to a surface of at least one of the first conductive layer and the second conductive layer. In this case, the strength of the high-frequency circuit having the slot formed therein can be ensured by the cover film.

[0021] 2. Details of the embodiments of the present disclosure

[0022] In the following drawings, the same reference numerals denote the same objects. 1 to 6 show a high-frequency circuit 10 according to an embodiment. The high-frequency circuit 10 according to the embodiment is configured as a flexible printed circuit (FPC) used for high-frequency signal transmission. An FPC has a structure in which a conductor such as copper foil is attached to a thin and soft insulating base film. Note that the high-frequency circuit 10 is not limited to an FPC, and may be a circuit formed on a rigid substrate.

[0023] As shown in FIG. 2, the high-frequency circuit 10 according to the embodiment includes a first dielectric layer 11, a circuit layer 21, a second dielectric layer 12, a first conductor layer 31, a second conductor layer 32, and an electromagnetic wave shield 150. The high-frequency circuit 10 according to the embodiment has a multilayer structure having three conductor layers. The number of conductor layers is not particularly limited, and may be two, four, five, or more. In FIG. 2, the conductor layer disposed in the middle of the three conductor layers is a circuit layer 21 having a high-frequency transmission path 21A. A first conductor layer 31, which is one of the three conductor layers, is disposed on the lower side of FIG. 2, which is one side of the circuit layer 21 in the thickness direction. A second conductor layer 32, which is the remaining one of the three conductor layers, is disposed on the upper side of FIG. 2, which is the other side of the circuit layer 21 in the thickness direction.

[0024] As shown in Fig. 3, the circuit layer 21 has a transmission line 21A and a ground pattern 21B located around the transmission line 21A. The area between the transmission line 21A and the ground pattern 21B is removed by etching, and the transmission line 21A and the ground pattern 21B are insulated from each other. In Fig. 3, the transmission line 21A is formed in a straight line, but may be formed in a bent shape. Around the transmission line 21A, a hole 21C is formed to become a part of a hole 151 for an electromagnetic wave shield 150 described later.

[0025] As shown in FIG. 2, a first dielectric layer 11 is provided between the circuit layer 21 and the first conductive layer 31. That is, the circuit layer 21 is provided on the first dielectric layer 11. In other words, the circuit layer 21 is provided above the first conductive layer 31 with the first dielectric layer 11 interposed therebetween. The circuit layer 21 and the first dielectric layer 11 are bonded together with an adhesive 60. As shown in FIG. 3, the first conductive layer 31 is configured with a ground pattern 31B over almost the entire surface thereof, except for a hole 31C which becomes a part of a hole 151 for an electromagnetic wave shield 150 described later. That is, the first conductive layer 31 is a ground layer.

[0026] The adhesive 60 is preferably one having excellent flexibility and heat resistance. The adhesive 60 is, for example, a resin-based adhesive such as modified polyphenylene ether, styrene resin, epoxy resin, butyral resin, or acrylic resin.

[0027] The main component of the adhesive 60 is preferably a thermosetting resin. The lower limit of the curing temperature of the thermosetting resin that is the main component of the adhesive 60 is preferably 120°C, more preferably 150°C. The upper limit of the curing temperature of the thermosetting resin that is the main component of the adhesive 60 is preferably 250°C, more preferably 230°C, and even more preferably 200°C. If the curing temperature of the thermosetting resin that is the main component of the adhesive 60 is higher than the above lower limit, the adhesive 60 is easy to handle. If the curing temperature of the thermosetting resin that is the main component of the adhesive 60 is lower than the above upper limit, the thermal deformation of the layers bonded by the adhesive 60 can be suppressed when the adhesive 60 is cured. The suppression of the thermal deformation can suppress a decrease in the dimensional accuracy of the high-frequency circuit 10.

[0028] The lower limit of the dielectric constant of the adhesive 60 is preferably as small as possible, but in order to satisfy other conditions such as insulation and mechanical strength, a practical limit is considered to be 1.5. The upper limit of the dielectric constant of the adhesive 60 is, for example, 3, preferably 2.8, and more preferably 2.6. Furthermore, if the dielectric constant of the adhesive 60 is smaller than the above upper limit, dielectric loss can be suppressed when transmitting a high-frequency signal in the high-frequency circuit 10.

[0029] As shown in Fig. 2, a second dielectric layer 12 is provided between the circuit layer 21 and the second conductor layer 32. That is, the second dielectric layer 12 is provided so that the circuit layer 21 is located between the second dielectric layer 12 and the first dielectric layer 11. As shown in Fig. 3, almost the entire surface of the second conductor layer 32 is formed by a ground pattern 32B, except for a transmission path 32A for a high-frequency signal and a hole 32C that is a part of a hole 151 for an electromagnetic wave shield 150. That is, the second conductor layer 32 is a ground layer.

[0030] 2, a first conductive layer 31 and a second conductive layer 32 functioning as ground layers are provided on both the top and bottom sides of the circuit layer 21, i.e., on both sides in the Z direction in Fig. 2. Therefore, of the electromagnetic waves radiated from the transmission line 21A, the electromagnetic waves radiated on both sides in the thickness direction of the high-frequency circuit 10, i.e., on both sides in the Z direction in Fig. 2, are shielded by the first conductive layer 31 and the second conductive layer 32.

[0031] Some of the electromagnetic waves radiated from the transmission line 21A are radiated in a direction parallel to the XY plane in FIG. 2. The electromagnetic waves radiated in a direction parallel to the XY plane cannot be blocked by the first conductive layer 31 and the second conductive layer 32, and may leak out of the high-frequency circuit 10 through the first dielectric layer 11 and the second dielectric layer 12. Therefore, the high-frequency circuit 10 of the embodiment includes an electromagnetic wave shield 150 for blocking the electromagnetic waves radiated in a direction parallel to the XY plane. The XY plane is a plane perpendicular to the thickness direction of the high-frequency circuit 10. The Z direction is the thickness direction of the high-frequency circuit 10, and corresponds to the stacking direction in the multi-layer structure of the conductive layers described above.

[0032] In the high-frequency circuit 10 according to the embodiment, electromagnetic waves radiated in the Z direction are blocked by the first conductive layer 31 and the second conductive layer 32. Electromagnetic waves radiated in a direction parallel to the XY plane are blocked by the electromagnetic wave shield 150. This effectively prevents the electromagnetic waves radiated from the transmission line 21A from leaking outside the high-frequency circuit 10. As a result, the effects of the leaked electromagnetic waves on other surrounding circuits can be suppressed.

[0033] The electromagnetic wave shield 150 is configured to function as a shield wall that blocks electromagnetic waves passing through the first dielectric layer 11 and the second dielectric layer 12 around the transmission line 21A. As shown in Fig. 1, the electromagnetic wave shield 150 is formed so as to surround the transmission line 21A in a plan view. In the embodiment, a plurality of electromagnetic wave shields 150 are provided at intervals D along a direction surrounding the transmission line 21A.

[0034] As shown in FIG. 2, the electromagnetic wave shield 150 is configured to include a ground conductor 152 on the inner surface of a hole 151 penetrating the first dielectric layer 11, the ground pattern 21B of the circuit layer 21, the second dielectric layer 12, the first conductive layer 31, and the second conductive layer 32. In the first conductive layer 31 and the second conductive layer 32, the ground conductor 152 is provided on the inner surface of the hole 151 formed in the ground patterns 31B and 32B. The ground conductor 152 exists so as to surround the transmission path 21A, and therefore can shield the electromagnetic waves passing through the first dielectric layer 11 and the second dielectric layer 12. Note that in the lower part of FIG. 1, the transmission path 21A is not surrounded by the electromagnetic wave shield 150. This is only because, for drawing purposes, the description of the electromagnetic wave shield 150 is omitted in accordance with the omission of the description of the transmission path 21A in the lower part of FIG. 1. Therefore, in reality, the electromagnetic wave shield 150 can also surround the lower side of the transmission path 21A.

[0035] As shown in Fig. 7, it was common knowledge that conventional shield vias 102 were circular in plan view. Therefore, in order to shield leakage electromagnetic waves, it was necessary to closely arrange many shield vias 102 so as to surround the signal transmission line 101. In contrast, in the embodiment shown in Fig. 1, the electromagnetic wave shield 150 has a long and thin shape along the direction surrounding the transmission line 21A. That is, the longitudinal dimension L of each electromagnetic wave shield 150 along the direction surrounding the transmission line 21A is larger than the width dimension W. Therefore, compared to circular shield vias 102, a smaller number of electromagnetic wave shields 150 can effectively shield leakage electromagnetic waves.

[0036] 4 and 5 show a manufacturing method of the high-frequency circuit 10 according to the embodiment. In step S11 shown in Fig. 4, a fluororesin substrate with copper on both sides is prepared as an example of a substrate. The fluororesin substrate with copper on both sides includes a fluororesin substrate constituting the second dielectric layer 12, copper constituting the circuit layer 21, and copper constituting the second conductor layer 32. The material of the substrate is not limited to fluororesin.

[0037] In step S12, through-holes 41 that penetrate the circuit layer 21, the second dielectric layer 12, and the second conductive layer 32 are formed at the positions of the transmission lines 21A and 32A.

[0038] In step S13, the inside of the through hole 41 is filled with a conductor by plating. This forms a via 40 that electrically connects the transmission line 21A and the transmission line 32A. The transmission line 32A functions as, for example, an external connection terminal for the transmission line 21A. Alternatively, the inner surface of the through hole 41 may be covered by plating, and the remaining space may be filled with a synthetic resin.

[0039] In step S14, the circuit layer 21 and the second conductive layer 32 of the fluororesin substrate with copper on both sides are etched to form the transmission path 21A of the circuit layer 21 and the transmission path 32A of the second conductive layer 32.

[0040] In step S15, a single-sided fluororesin substrate is attached to the circuit layer 21 side. The single-sided fluororesin substrate comprises a fluororesin substrate constituting the first dielectric layer 11 and copper constituting the first conductor layer 31. In step S15, the first dielectric layer 11 and the circuit layer 21 are attached to each other with an adhesive 60 so that they face each other. The adhesive 60 is, for example, a bonding sheet. The bonding sheet is used to bond between layers of the substrate. The bonding sheet has insulating properties and adhesive properties.

[0041] In step S31 following step S15, a plurality of holes 151 that continuously penetrate from the first conductive layer 31 to the second conductive layer 32 are formed by press punching to form the electromagnetic wave shield 150. The method for forming the holes 151 is not limited to press punching, but using press punching is advantageous because it allows the plurality of holes 151 to be formed simultaneously. The holes 151 may also be formed by laser processing.

[0042] The holes 151 are provided at intervals D along the direction surrounding the transmission line 21A. Each of the holes 151 has a longitudinal dimension L along the direction surrounding the transmission line 21A and a width dimension W perpendicular to the longitudinal dimension L. Each of the holes 151 is an elongated hole. That is, the longitudinal dimension L of each of the holes 151 is larger than the width dimension W. The longitudinal dimension L is preferably larger than 5 times the width dimension W, more preferably larger than 10 times the width dimension W, further preferably larger than 15 times the width dimension W, and further preferably larger than 20 times the width dimension W. By making the longitudinal dimension L sufficiently larger than the width dimension W, the number of holes 151 can be reduced. Furthermore, by making the width dimension W sufficiently smaller than the longitudinal dimension L, the area of ​​the region required to form the electromagnetic wave shield 150 around the transmission line 21A can be reduced.

[0043] The longitudinal dimension L is greater than the interval D. The longitudinal dimension L is preferably greater than 5 times the interval D, more preferably greater than 10 times the interval D, more preferably greater than 15 times the interval D, and even more preferably greater than 20 times the interval D. In order to suppress leakage of electromagnetic waves at the interval D, the interval D is preferably smaller than 1 / 4 of the wavelength λ of the high frequency transmitted by the transmission line 21A, more preferably smaller than 1 / 8 of the wavelength λ, and even more preferably smaller than 1 / 16 of the wavelength λ. The smaller the interval D, the more the leakage of electromagnetic waves can be suppressed. By making the interval D smaller than 1 / 16 of the wavelength λ, the leakage of electromagnetic waves can be sufficiently reduced.

[0044] By providing the interval D between the multiple holes 151, it is possible to prevent a decrease in strength of the high-frequency circuit 10, compared to a case in which a single hole 151 is formed long and continuous.

[0045] The larger the width dimension W, the thicker the electromagnetic wave shield 150 becomes, and therefore the larger the allowable spacing D. In other words, by increasing the width dimension W, it is possible to reduce the leakage of electromagnetic waves even if the spacing D of the gaps between the multiple holes 151 is the same.

[0046] In step S32, conductor 152 is formed on the inner surface of hole 151 by plating. Fig. 2 shows a case where conductor 152 is provided in contact with the entire inner surface of hole 151 and is formed into a cylindrical shape having an outer circumferential shape corresponding to the inner circumferential shape of hole 151. Conductor 152 may be formed only on the surface of the inner surface of hole 151, or may be formed so as to completely fill the inside of hole 151. The inside of conductor 152 may be filled with a dielectric material such as synthetic resin, or with a conductor such as conductive paste.

[0047] The conductor 152 electrically connects the ground pattern 21B, the ground pattern 31B, and the ground pattern 32B. Therefore, the conductor 152 is a ground conductor 152. The ground conductor 152 is provided inside each of the multiple holes 151 surrounding the periphery of the transmission line 21A. Therefore, the multiple ground conductors 152 formed in the multiple holes 151 function as an electromagnetic wave shield 150 surrounding the periphery of the transmission line 21A. The ground conductor 152 can block electromagnetic waves radiated through the first dielectric layer 11 and the second dielectric layer 12.

[0048] That is, the conductor 152 electrically connects the ground pattern 21B of the circuit layer 21 and the ground pattern 31B of the first conductor layer 31. Therefore, the conductor 152 has the same potential as the ground patterns 21B, 31B, and serves as the ground conductor 152. The ground conductor 152 is provided in the hole 151 surrounding the periphery of the transmission line 21A, and therefore functions as an electromagnetic wave shield 150 surrounding the periphery of the transmission line 21A. The ground conductor 152 located in the first dielectric layer 11 can block electromagnetic waves radiated through the first dielectric layer 11.

[0049] Moreover, the conductor 152 electrically connects the ground pattern 21B of the circuit layer 21 and the ground pattern 32B of the second conductor layer 32. Therefore, the conductor 152 has the same potential as the ground patterns 21B, 32B, and serves as the ground conductor 152. The ground conductor 152 is provided in a hole 151 that surrounds the periphery of the transmission line 21A, and therefore functions as an electromagnetic wave shield 150 that surrounds the periphery of the transmission line 21A. The ground conductor 152 located in the second dielectric layer 12 can block electromagnetic waves radiated through the second dielectric layer 12.

[0050] In step S33, cover films 71, 72 are attached via adhesives 81, 82 to the surfaces of the first conductive layer 31 and the second conductive layer 32, respectively. The cover films 71, 72 are made of, for example, polyimide, and protect the first conductive layer 31 and the second conductive layer 32. By attaching the cover films 71, 72, the strength of the high-frequency circuit 10 in which the hole 151 is formed can be ensured.

[0051] The multiple electromagnetic wave shields 150 and holes 151 shown in Fig. 1 are formed in a single row around the transmission line 21A, but may be formed in multiple rows to surround the transmission line 21A as shown in Fig. 6. Fig. 6 shows a case where the multiple electromagnetic wave shields 150 and holes 151 are arranged in two rows, inside and outside.

[0052] 6 includes a first shield 150A provided around the transmission line 21A and a second shield 150B provided on the outer periphery of the first shield 150A. Another shield may be provided on the outer periphery of the second shield 150B.

[0053] The first shield 150A is configured with a ground conductor 152 on the inner surface of a plurality of first holes 151A that continuously penetrate from the first conductive layer 31 to the second conductive layer 32, similar to the hole 151. Each of the plurality of first holes 151A is an elongated hole, similar to the hole 151, and may be referred to as a first elongated hole here. A row of the plurality of first holes 151A forms a first row that is spaced apart along a direction surrounding the periphery of the transmission line 21A. Similar to the hole 151, each of the plurality of first elongated holes 151A has a longitudinal dimension L along the direction surrounding the transmission line 21A that is greater than a width dimension W.

[0054] The second shield 150B is configured with a ground conductor 152 on the inner surface of a plurality of second holes 151B that continuously penetrate from the first conductive layer 31 to the second conductive layer 32, similar to the hole 151. Each of the plurality of second holes 151B is an elongated hole, similar to the hole 151, and may be referred to as a second elongated hole here. A row of the plurality of second holes 151B forms a second row that is spaced apart along a direction surrounding the periphery of the transmission line 21A, on the outer circumferential side of the plurality of first elongated holes 151A. Each of the plurality of second elongated holes 151B has a longitudinal dimension L along a direction surrounding the transmission line 21A that is larger than a width dimension W, similar to the hole 151.

[0055] The second slots 151B are arranged so as to be present at positions corresponding to the spaces between the first slots 151A. That is, the second slots 151B are arranged so as to close the spaces between the first slots 151A from the outer periphery of the first slots 151A. Therefore, the second shield 150B formed by the ground conductor 152 in the second slots 151B can block the leakage electromagnetic waves from the spaces between the first shields 150A. Thus, in FIG. 6, the row of the second shields 150B, which are the outer electromagnetic shields, is arranged so as to block the leakage electromagnetic waves from the row of the first shields 150A, which are the inner electromagnetic shields. By providing a plurality of rows of the electromagnetic shields 150, the leakage electromagnetic waves can be efficiently blocked. In addition, since the first holes 151A and the second holes 151B are slots, the leakage electromagnetic waves can be efficiently blocked even with a small number of rows.

[0056] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include the meaning equivalent to the claims and all modifications within the scope. [Explanation of symbols]

[0057] 10: High frequency circuits 11: First dielectric layer 12: Second dielectric layer 21:Circuit layer 21A: Transmission line 21B: Ground pattern 21C: Hole 31: First conductive layer 31C: Hole 31B: Ground pattern 32: Second conductive layer 32A: Transmission line 32B: Ground pattern 32C: Hole 40: Via 41:Through hole 60: Adhesive 71: Cover film 72: Cover film 81: Adhesive 82: Adhesive 100: High frequency circuits 101: Signal transmission line 102: Shield via 150: Electromagnetic shielding 150A: 1st shield 150B: Second shield 151 :hole 151A: 1st hole, 1st long hole 151B: 2nd hole, 2nd long hole 152 : Conductor, ground conductor L: Longitudinal dimension W: Width dimension D: Spacing

Claims

1. A first dielectric layer; a circuit layer provided on the first dielectric layer, the circuit layer including a transmission path for a high-frequency signal and a ground pattern arranged around the transmission path; a second dielectric layer provided such that the circuit layer is located between the first dielectric layer and the second dielectric layer; a first conductor layer disposed between the first dielectric layer and the circuit layer; a second conductor layer disposed between the circuit layer and the second dielectric layer; an electromagnetic wave shield provided around the transmission line; Equipped with the electromagnetic wave shield is configured to include a ground conductor on an inner surface of a plurality of holes passing through the first dielectric layer, the ground pattern, the second dielectric layer, the first conductive layer, and the second conductive layer; the plurality of holes are a plurality of elongated holes provided at intervals along a direction surrounding the transmission line, Each of the plurality of long holes has a longitudinal dimension along a direction surrounding the transmission line that is greater than a width dimension thereof, the circuit layer and the first dielectric layer are bonded together by an adhesive; The adhesive has a dielectric constant of less than 3. High frequency circuits.

2. The longitudinal dimension is greater than five times the width dimension. The high frequency circuit according to claim 1 .

3. The longitudinal dimension is greater than the spacing. The high frequency circuit according to claim 1 or 2.

4. The longitudinal dimension is greater than five times the spacing. The high frequency circuit according to claim 3.

5. Each of the plurality of holes continuously penetrates the first dielectric layer, the ground pattern, the second dielectric layer, the first conductive layer, and the second conductive layer. The high-frequency circuit according to claim 1 .

6. the electromagnetic wave shield includes at least a first shield provided around the transmission line and a second shield provided on an outer circumferential side of the first shield, the first shield is configured to include the ground conductor on inner surfaces of a plurality of first holes penetrating the first dielectric layer, the ground pattern, the second dielectric layer, the first conductive layer, and the second conductive layer; the plurality of first holes are a plurality of first elongated holes provided at intervals along a direction surrounding the transmission line, Each of the first slots has a longitudinal dimension along a direction surrounding the transmission line that is greater than a width dimension thereof, the second shield is configured to include the ground conductor on inner surfaces of a plurality of second holes penetrating the first dielectric layer, the ground pattern, the second dielectric layer, the first conductive layer, and the second conductive layer on an outer circumferential side of the plurality of first holes, the second holes are second elongated holes provided at intervals along a direction surrounding the transmission line, Each of the second slots has a longitudinal dimension along a direction surrounding the transmission line that is greater than a width dimension thereof, The second shield is disposed to block electromagnetic waves leaking from between the first slots. The high-frequency circuit according to claim 1 .

7. a cover film attached to at least one surface of the first conductive layer and the second conductive layer; The high-frequency circuit according to claim 1 .

8. A first dielectric layer; a circuit layer provided on the first dielectric layer, the circuit layer including a transmission path for a high-frequency signal and a ground pattern arranged around the transmission path; a second dielectric layer provided such that the circuit layer is located between the first dielectric layer and the second dielectric layer; a first conductor layer disposed between the first dielectric layer and the circuit layer; a second conductor layer disposed between the circuit layer and the second dielectric layer; an electromagnetic wave shield provided around the transmission line; Equipped with the electromagnetic wave shield includes at least a first shield provided around the transmission line and a second shield provided on an outer circumferential side of the first shield, the first shield is configured to include a ground conductor on inner surfaces of a plurality of first holes penetrating the first dielectric layer, the ground pattern, the second dielectric layer, the first conductive layer, and the second conductive layer; the plurality of first holes are a plurality of first elongated holes provided at intervals along a direction surrounding the transmission line, Each of the first slots has a longitudinal dimension along a direction surrounding the transmission line that is greater than a width dimension thereof, the second shield is configured to include a ground conductor on inner surfaces of a plurality of second holes penetrating the first dielectric layer, the ground pattern, the second dielectric layer, the first conductive layer, and the second conductive layer on an outer circumferential side of the plurality of first holes, the second holes are second elongated holes provided at intervals along a direction surrounding the transmission line, Each of the second slots has a longitudinal dimension along a direction surrounding the transmission line that is greater than a width dimension thereof, The second shield is disposed to block electromagnetic waves leaking from between the first slots. High frequency circuits.

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