JP2020174114A - Multilayer circuit board - Google Patents

Abstract

To provide a multilayer circuit board that can improve the productivity of a substrate including a high frequency circuit.SOLUTION: A multilayer circuit board 30 in which a first circuit board 10 including a high-frequency board and the second circuit board 20 joined to the first circuit board 10 are overlapped and joined in the thickness direction includes a connection portion 35 that electrically connects the first circuit board 10 and the second circuit board 20, and a high frequency material layer 32 arranged around the connection portion 35 between the first circuit board 10 and the second circuit board 20.SELECTED DRAWING: Figure 1

Description

The present invention relates to a multilayer circuit board.

In an antenna module used in a base station or a terminal of a radio station, a high frequency signal generated by a high frequency (RF) integrated circuit (IC) is radiated from the antenna via a feeding circuit. A multilayer board is generally used in order to facilitate the routing of signal lines and reduce the board area. However, a special and expensive dielectric material is used for the substrate corresponding to the high frequency band. Further, Patent Document 1 proposes a composite substrate using a general substrate material for a power supply circuit or the like and a substrate material corresponding to a high frequency band for a high frequency circuit portion.

JP-A-2016-40797

In Patent Document 1, through holes are used for electrical connection between a base substrate using a general substrate material and a high frequency substrate having excellent high frequency characteristics. For this reason, a drilling process is required through the base substrate and the high frequency substrate, and the productivity is low. Further, it is necessary to redundantly route the high frequency signal by providing the through hole, which may cause deterioration of the characteristics.

The present invention has been made in view of the above problems, and provides a multilayer circuit board capable of improving the productivity of a substrate including a high frequency circuit.

In order to solve the above problems, in the present invention, the first circuit board including the high frequency substrate and the second circuit board to be bonded to the first circuit board are laminated and joined in the respective thickness directions. In the circuit board, between the first circuit board and the second circuit board, a connection portion for electrically connecting the first circuit board and the second circuit board, and the connection portion. Provided is a multilayer circuit board characterized by having a high frequency material layer arranged around the circuit board.

The connection may include a piece of metal.
The connecting portion may have a pillar shape containing at least one metal such as copper, gold, aluminum and tungsten.
The connection portion may include at least one of a solder layer and a conductive paste layer.
The high-frequency substrate and the high-frequency material layer may each be composed of an insulating material having a dielectric loss of less than 0.01.

An antenna capable of transmitting or receiving or transmitting / receiving a high frequency signal may be formed on the first circuit board.
A feeder that feeds at least one of the antennas may be arranged in the same layer as the antenna.
The feeder that feeds at least one of the antennas may not be arranged in the same layer as the antenna.
The antenna may have a non-feeding element.
A dielectric layer may be laminated on the surface of the first circuit board on which the antenna is formed.
An integrated circuit (IC) for processing a high frequency signal may be mounted on at least one of the first circuit board and the second circuit board.

According to the present invention, it is possible to provide a multilayer circuit board capable of improving the productivity of a substrate including a high frequency circuit.

It is sectional drawing which illustrates the multilayer circuit board of 1st Embodiment. It is sectional drawing which illustrates the appearance of providing the high frequency material layer between each circuit board. It is sectional drawing which illustrates the appearance of arranging a metal piece in a high frequency material layer.

Hereinafter, the present invention will be described with reference to the drawings based on the preferred embodiments.

FIG. 1 shows the multilayer circuit board 30 of the first embodiment. The multilayer circuit board 30 is configured by joining the first circuit board 10 and the second circuit board 20. The first circuit board 10 is configured by laminating a plurality of insulating substrates 11a, 11b, 11c, 11d, 11e, and 11f. The second circuit board 20 is configured by laminating a plurality of insulating substrates 21a, 21b, 21c, 21d, 21e, and 21f. The number of layers of the insulating substrate included in the first circuit board 10 and the second circuit board 20 is not particularly limited, and may be one layer or two or more layers, respectively. Each insulating substrate can be composed of a film, a sheet, a prepreg, or the like. Although not particularly shown, a conductor layer can be provided on one side or both sides of the insulating substrate. Further, a through conductor may be provided by penetrating one layer or two or more layers of the insulating substrate.

The first circuit board 10 includes a high frequency board. The high frequency substrate is an insulating substrate that supports high frequencies. Examples of the high-frequency material constituting the high-frequency substrate include an insulating material having a dielectric loss of less than 0.01. In the present specification, the insulating material means an electrically insulating material (dielectric, non-conductive material), and does not need to be a heat insulating material (insulating material). Further, the measurement condition of the dielectric loss is defined as the dielectric loss tangent (tan δ) of JIS C 6781 (copper-clad laminate test method for printed wiring board), for example, the temperature is 20 ± 2 ° C. with respect to the measurement frequency of 1 MHz. , Relative humidity 60-70%. A high frequency substrate made of a high frequency material having a dielectric loss of 0.005 or less is more preferable. Specific examples of the high-frequency material constituting the high-frequency substrate include liquid crystal polymer (LCP), polyphenylene ether (PPE) resin, fluororesin, cycloolefin resin, maleimide resin, polyimide resin, modified polyimide resin, polyphenylene sulfide (PPS) resin, and the like. One or more selected from the group consisting of quartz, ceramic, and sapphire can be mentioned. The number of layers of the first circuit board 10 is not particularly limited, and examples thereof include 1 to 6 layers.

The first circuit board 10 may be a core substrate or a multilayer substrate composed of prepregs having a thickness of 100 μm or less in each layer, and a core substrate or prepreg having a thickness of more than 100 μm may be used as necessary for reducing loss. It may be included. In the first embodiment, the insulating substrates 11a, 11b, 11c, 11d, 11e, and 11f included in the first circuit board 10 are all composed of high frequency substrates, but the present invention is not limited thereto. The insulating substrate included in the first circuit board 10 does not have to be all composed of a high frequency substrate.

An antenna 12 capable of transmitting, receiving, or transmitting and receiving a high frequency signal is formed on the first circuit board 10 of the first embodiment as an example of a high frequency element. For the purpose of securing a band, suppressing loss of high-frequency signals, for example, a substrate made of a high-frequency material may be bonded with an adhesive or a build-up layer made of a prepreg may be provided as a layer in contact with the antenna 12. .. In that case, at least a part of the layer other than the layer on which the antenna 12 of the first circuit board 10 is formed may not be composed of the high frequency material. The antenna 12 is not particularly limited as long as it has a structure that can be mounted or incorporated on a substrate, but for example, a flat antenna is preferable, and a patch antenna, a strip antenna, a slot antenna, and the like can be mentioned. A waveguide structure such as a post-wall waveguide (PWW) may be configured on the substrate, and an antenna may be configured by slots, openings, or the like of the waveguide. The antenna 12 may form an antenna array.

In the example shown in FIG. 1, the antenna 12 is formed on the insulating substrate 11a of the layer farthest from the second circuit board 20 in the thickness direction of the first circuit board 10. When the antenna 12 transmits a signal in the air or receives a signal from the air, the first circuit board so that the side opposite to the second circuit board 20 is the side in the air in the thickness direction of the first circuit board 10. 10 can be installed. Although not particularly shown, it is also possible to provide the antenna 12 on the other insulating substrates 11b, 11c, 11d, 11e, 11f of the first circuit board 10. The positions of the conductor layers or through conductors (not shown) provided on the insulating substrates 11a, 11b, 11c, 11d, 11e, and 11f are designed in consideration of the influence on the transmission or reception of the aerial signal in the antenna 12.

The second circuit board 20 may include a high frequency substrate at least in part, but the insulating material of the second circuit board 20 may be composed of only a general insulating material that is not compatible with high frequencies. The insulating substrate included in the second circuit board 20 can be made of a general insulating material having a higher dielectric loss than the high frequency material constituting the high frequency substrate. Examples of the insulating material that is not compatible with high frequencies include an insulating material having a dielectric loss of 0.01 or more. Specific examples of the insulating material constituting the insulating substrate include glass cloth base epoxy resin (FR-4, etc.), glass cloth / glass non-woven composite base epoxy resin, glass cloth / paper composite base epoxy resin, and synthetic fiber cloth. Examples thereof include a base material epoxy resin, a paper base material epoxy resin, a glass cloth base material polyimide resin, a glass cloth base material bismaleimide / triazine / epoxy resin, a paper base material phenol resin, and a flexible base material such as polyimide.

As the second circuit board 20, a core substrate having a thickness of 100 μm or less or a multilayer substrate composed of a prepreg is preferable. As a result, the thickness of the substrate is thin and processing becomes easy. The number of layers of the second circuit board 20 is not particularly limited, but is typically 4 to 10 layers, and may exceed 10 layers.

In order to increase the gain of the antenna 12, it is preferable to increase the number of antennas 12 formed on the first circuit board 10. Therefore, in the first embodiment, the integrated circuit 22 that processes the high frequency signal is not mounted on the first circuit board 10, but the integrated circuit 22 that processes the high frequency signal is mounted on the second circuit board 20. The integrated circuit 22 is connected to the second circuit board 20 via a bump 23 made of a conductor such as solder between the integrated circuit 22 and the conductor pattern 24 of the second circuit board 20. Examples of the integrated circuit 22 include integrated circuits (ICs) such as RFICs. In an antenna board that handles high-frequency signals, in order to suppress signal loss from the RFIC, the first circuit board on which the antenna is formed and the second circuit board on which the RFIC is mounted are integrated into the same multilayer circuit board. It is preferable that the configuration is as follows. As a result, the signal line can be easily routed and the substrate area can be suppressed. Since the substrate material for high frequency is expensive, the power supply circuit, the circuit for propagating the low frequency baseband signal, etc. are mounted on the second circuit board, and each insulating substrate constituting the second circuit board is not compatible with high frequency. , A general insulating material can be used. For example, if the signal is less than 10 GHz (about several GHz), it can be propagated by a coaxial cable or the like.

For example, when a high-frequency signal is generated by the integrated circuit 22, the high-frequency signal can be propagated inside the multilayer circuit board 30 to be supplied to the antenna 12 and radiated from the antenna 12 into the air. The wiring connecting the integrated circuit 22 and the antenna 12 preferably shortens the transmission distance in order to reduce the loss of high frequency signals. Therefore, the multilayer circuit board 30 has a configuration in which the first circuit board 10 and the second circuit board 20 are overlapped in their respective thickness directions and composited by joining. The total thickness of the multilayer circuit board 30 is, for example, 1 to 2 mm, specifically about 1.5 mm. The antenna 12 may have a non-feeding element, if necessary. For example, in a patch antenna, the characteristics can be improved by installing a non-feeding patch around the radiation patch.

When the integrated circuit 22 generates a high-frequency signal, at least the layer on which the integrated circuit 22 of the second circuit board 20 is mounted is used as the high-frequency board, and the wiring connected to the signal line and the ground layer of the mounted integrated circuit 22 is re-wired. It may be arranged.

The first circuit board 10 has a first joint surface 13 on one of the surfaces perpendicular to the thickness direction. Further, the second circuit board 20 has a second joint surface 25 on at least one of the surfaces perpendicular to the thickness direction. The multilayer circuit board 30 has a configuration in which the first circuit board 10 and the second circuit board 20 are joined so that the first joint surface 13 and the second joint surface 25 face each other. Although not particularly shown, the second circuit board 20 has a second bonding surface 25 on both surfaces perpendicular to the thickness direction, and the first circuit board 10 is bonded to each of the second bonding surfaces 25. May be done. When the first circuit board 10 is joined to both surfaces perpendicular to the thickness direction of the second circuit board 20, the structure has high symmetry in the thickness direction, so that the warp of the substrate can be easily suppressed.

In the first embodiment, the integrated circuit 22 is mounted on the second circuit board 20, but the present invention is not limited to this. The integrated circuit 22 may be mounted on the first circuit board 10. Further, one or more integrated circuits 22 may be mounted on each of the first circuit board 10 and the second circuit board 20.

In order to realize the electrical connection between the first circuit board 10 and the second circuit board 20, the multilayer circuit board 30 has a connection portion 35 between the first joint surface 13 and the second joint surface 25. The connection portion 35 is a connection portion between boards. The connecting portion 35 includes a metal piece 31. The metal piece 31 has a pillar shape.
Examples of the material of the metal piece 31 include at least one metal of copper, gold, aluminum, and tungsten from the viewpoint of conductivity and the like. The metal piece 31 may be made of an alloy such as a copper alloy, a gold alloy, an aluminum alloy, or a tungsten alloy.

The connecting portion 35 may include at least one of a solder layer and a conductive paste layer in addition to the metal piece 31. Conductive layers 14 and 26 made of a solder layer and a conductive paste layer may be formed on the surface of the metal piece 31 facing the first joint surface 13 or the surface of the metal piece 31 facing the second joint surface 25. The surface of the metal piece 31 in contact with the conductive layers 14 and 26 may be a curved surface or a flat surface. In the first embodiment, the conductive layers 14 and 26 are formed, but the present invention is not limited to this. Only the conductive layer 14 may be formed, or only the conductive layer 26 may be formed. When both the conductive layers 14 and 26 are formed, both may be solder layers, both may be conductive paste layers, one may be a solder layer and the other may be a conductive paste layer.

The solder constituting the solder layer can be appropriately selected from various types of solder such as solder balls and solder paste. In the product of the multilayer circuit board 30, the solder forming the solder layer after bonding may be layered by reflow.
Examples of the conductor used in the conductive paste layer include metal particles such as gold, silver and copper, and conductive carbon such as carbon black, graphite and carbon nanotubes. The conductive paste layer can be composed of various conductive pastes such as silver paste, copper paste, and conductive carbon paste. The conductive paste layer may be in the form of a paste having fluidity or deformability in the manufacturing process, and in the product of the multilayer circuit board 30, the conductive paste layer after bonding has fluidity or deformability due to firing, curing, or the like. You don't have to.

When the metal piece 31 is a Cu pillar or the like, the solder layer and the conductive paste layer have fluidity and deformability, so that the space between the metal piece 31 and the first joint surface 13 or the second joint surface 25 can be filled. The fluidity or deformability of the solder layer may be realized by reflow during manufacturing, and the solder layer does not have to have fluidity or deformability in the product of the multilayer circuit board 30. The fluidity or deformability of the conductive paste layer may be realized in an uncured state at the time of manufacture, and in the product of the multilayer circuit board 30, the conductive paste layer does not have to have fluidity or deformability. When the size of the metal piece 31 along the substrate surface is taken as the diameter, the thickness of the metal piece 31 may be larger than the diameter, the thickness may be smaller than the diameter, and the thickness and the diameter may be the same.

A high-frequency material layer 32 made of a high-frequency material is formed in a region between the first joint surface 13 and the second joint surface 25 where the connection portion 35 is not formed. Examples of the high-frequency material constituting the high-frequency material layer 32 include an insulating material having a dielectric loss of less than 0.01. A high frequency material layer 32 composed of a high frequency material having a dielectric loss of 0.005 or less is more preferable. Specific examples of the high-frequency material constituting the high-frequency material layer 32 include liquid crystal polymer (LCP), polyphenylene ether (PPE) resin, fluororesin, cycloolefin resin, maleimide resin, polyimide resin, modified polyimide resin, and polyphenylene sulfide (PPS). One or more selected from the group consisting of resin, quartz, ceramic, and sapphire can be mentioned. The material constituting the high-frequency material layer 32 may be the same as or different from the material constituting the high-frequency substrate of the first circuit board 10. By arranging the high frequency material layer 32 around the connecting portion 35, the loss in the connecting portion 35 can be suppressed. The high frequency material layer 32 may have a hole 33 having a gap 34 between the high frequency material layer 32 and the connecting portion 35. Further, the high frequency material layer 32 may be in contact with at least a part of the connecting portion 35.

The mechanical bonding between the first bonding surface 13 and the second bonding surface 25 may involve at least one of the connecting portion 35 or the high frequency material layer 32. The connection portion 35 can also be reinforced by the high frequency material layer 32. The high frequency material layer 32 preferably has an adhesive force with respect to the first circuit board 10 and the second circuit board 20. When the high frequency material layer 32 is made of an adhesive material, the state in the joining step is not particularly limited, and examples thereof include a sheet, a paste, a gel, and a liquid. In the product of the multilayer circuit board 30, the adhesive material after joining may be in a cured state or a dried state.

As a method for manufacturing the multilayer circuit board 30 of the first embodiment, a step of manufacturing a first circuit board 10 on which an antenna 12 is formed, a step of manufacturing a second circuit board 20 on which an integrated circuit 22 is mounted, and a drawing. As shown in FIG. 2, a step of arranging the high-frequency material layer 32 between the first circuit board 10 and the second circuit board 20, and as shown in FIG. 3, a hole 33 is formed in the high-frequency material layer 32 and a metal piece 31 is formed. As shown in FIG. 1, a manufacturing method including a step of joining the first circuit board 10 and the second circuit board 20 and forming a connecting portion 35 including a metal piece 31 can be mentioned. After preparing the first circuit board 10 and the second circuit board 20 as separate circuit boards, the first circuit board 10 and the second circuit board 20 are joined via the connection portion 35 to form the first circuit. High frequency signals can be exchanged between the substrate 10 and the second circuit board 20.

Prior to the joining process in which the first circuit board 10 and the second circuit board 20 are aligned and connected by the metal pieces 31, the conductive layers 14 and 26 are provided at positions corresponding to the metal pieces 31. Is preferable. The conductive layer 14 is arranged at a position corresponding to the metal piece 31 on the first joint surface 13. The conductive layer 26 is arranged at a position corresponding to the metal piece 31 on the second joint surface 25.

In the first embodiment, when the hole 33 shown in FIG. 3 is formed in the high frequency material layer 32 as shown in FIG. 2, the high frequency material layer 32 is adhered to the second circuit board 20 and the first circuit board 10 is formed. May be removed by photolithography, machining, laser processing, or the like without arranging the high frequency material layer 32 in the vicinity of the second circuit board 20. The high-frequency material layer 32 in which the holes 33 are formed covers at least the vicinity of the conductive layer 26 in the second joint surface 25. When the metal piece 31 is arranged in the hole 33 of the high frequency material layer 32, the high frequency material layer 32 may be separated from the outer periphery of the metal piece 31, and the metal piece 31 adheres to the high frequency material layer 32 so as to fill the hole 33. You may. By making the hole 33 larger than the metal piece 31, a gap 34 is created between the hole 33 and the metal piece 31, so that the metal piece 31 can be easily arranged.

Although no specific example is shown, the order in which the metal piece 31 and the high-frequency material layer 32 are arranged between the first circuit board 10 and the second circuit board 20 is not particularly limited. After arranging the metal piece 31 and the high frequency material layer 32 on the first circuit board 10, the joining step may be performed. After arranging the metal piece 31 and the high frequency material layer 32 on the second circuit board 20, the joining step may be performed. The joining step may be performed after the metal piece 31 is arranged on the first circuit board 10 and the high frequency material layer 32 is arranged on the second circuit board 20. The joining step may be performed after the metal piece 31 is arranged on the second circuit board 20 and the high frequency material layer 32 is arranged on the first circuit board 10. After integrating the metal piece 31 and the high frequency material layer 32, the joining step may be performed.
Further, the order in which the metal piece 31 and the high-frequency material layer 32 are arranged on one of the first joint surface 13 and the second joint surface 25 is not particularly limited. The high-frequency material layer 32 may be arranged after the metal piece 31 is arranged, the metal piece 31 may be arranged after the high-frequency material layer 32 is arranged, or the metal piece 31 and the high-frequency material layer 32 may be arranged at the same time. Good.

As described in Patent Document 1, when through holes are formed over all layers of a multilayer circuit board, the length of the through holes becomes long, which makes manufacturing difficult. Increasing the diameter of the through hole facilitates manufacturing, but reduces area efficiency.

According to the multilayer circuit board 30 of the first embodiment, since a high frequency signal can be transmitted via the connection portion 35 including the metal piece 31, an interlayer through hole is provided in the first circuit board 10 or the second circuit board 20. Even when the through holes are provided, the maximum length of the through holes is the thickness of the first circuit board 10 or the second circuit board 20. Therefore, productivity can be improved. Further, since the diameter of the through hole can be reduced, the area efficiency of the substrate can be improved.

A feed line for feeding power to the antenna 12 is appropriately provided inside the second circuit board 20 between the conductor pattern 24 on which the integrated circuit 22 is mounted and the connection portion 35. Further, inside the first circuit board 10, a feeding line is appropriately provided between the connecting portion 35 and the antenna 12. When the conductive layers 14 and 26 are omitted in the connecting portion 35, the feeding line may be directly connected to the metal piece 31. Although the elements constituting the feeder are partially shown in FIGS. 1 to 3, the creeping connection portions 10a and 20a along the substrate surface and the interlayer connection portions 10b and 20b along the thickness direction of the substrate are shown. And can be mentioned.

The form of the feeding line is not particularly limited, but may be composed of a microstrip line, a strip line, a through hole, a via, or the like. The creepage connection portion that connects the position of the connection portion 35 and the position of the antenna 12 in the direction along the substrate surface of the first circuit board 10 is provided in a layer different from the antenna 12, and is provided from a layer different from the antenna 12. It is preferable to have an interlayer connection portion in the thickness direction of the first circuit board 10 toward the antenna 12. The feeder line of the first circuit board 10 has only an interlayer connection portion between the layer of the antenna 12 and the layer of the creepage connection portion, and does not have another connection portion. In this case, unnecessary radiation from the feeder can be suppressed, so that the characteristics of the multilayer circuit board can be improved.

On the other hand, when the creepage connection portion is arranged along the same layer as the antenna 12, it is not necessary to provide the interlayer connection portion from a layer different from the antenna 12 toward the antenna 12. Therefore, the number of layers of the insulating substrate constituting the first circuit board 10 can be reduced, which is advantageous in manufacturing the first circuit board 10. Whether the feeder line is connected to the antenna 12 via the creepage connection portion or the interlayer connection portion can be appropriately selected. The antenna 12 to which the feeder line is connected via the creepage connection portion and the antenna 12 to which the feeder line is connected via the interlayer connection portion may be used together with the first circuit board 10.

Although not particularly shown, a dielectric layer may be formed on the surface of the first circuit board 10 on which the antenna 12 is formed. The method for forming the dielectric layer is not particularly limited, and examples thereof include a method of attaching and coating the dielectric layer on the antenna 12. In the dielectric layer, the substance that the radiation patch or the non-feeding patch comes into contact with is changed from air (dielectric constant 1.0) to a dielectric, so that the antenna 12 avoids the influence on the transmission or reception of the aerial signal. , A conductor layer, an insulating layer having no conductor such as a through conductor. Further, the antenna 12 can be protected by the dielectric layer. When the antenna 12 has a radiating element and a non-feeding element, a dielectric layer can be formed on both the radiating element and the non-feeding element.

Although the present invention has been described above based on the preferred first embodiment, the present invention is not limited to the above-mentioned first embodiment, and various modifications can be made without departing from the gist of the present invention. Modifications include additions, replacements, omissions, and other changes to each component described in accordance with the first embodiment. It is also possible to appropriately combine the components described based on the first embodiment. For example, the connecting portion 35 may be formed by omitting the metal piece 31 and using only at least one of the conductive layers 14 and 26. Further, the metal piece 31 is not limited to the pillar shape, and may have other shapes such as a plate shape and a foil shape.

The frequency of the high frequency signal is not particularly limited, and examples thereof include 30 to 300 GHz and 60 to 80 GHz. Examples of high-frequency elements applicable to high-frequency circuits include antennas, waveguides, filters, diplexers, directional couplers, distributors, photoelectric conversion elements, and the like.

10 ... 1st circuit board, 10a ... creepage connection part, 10b ... interlayer connection part, 11a, 11b, 11c, 11d, 11e, 11f ... insulation board, 12 ... antenna, 13 ... first junction surface, 14 ... conductive layer, 20 ... 2nd circuit board, 20a ... creepage connection, 20b ... interlayer connection, 21a, 21b, 21b, 21c, 21d, 21e, 21f ... insulation board, 22 ... integrated circuit, 23 ... bump, 24 ... conductor pattern, 25 ... 2nd joint surface, 26 ... Conductive layer, 30 ... Multilayer circuit board, 31 ... Metal piece, 32 ... High frequency material layer, 33 ... Hole, 34 ... Gap, 35 ... Connection part.

Claims (11)

A multilayer circuit board in which a first circuit board including a high-frequency board and a second circuit board joined to the first circuit board are overlapped and joined in the respective thickness directions.
Between the first circuit board and the second circuit board, a connection portion for electrically connecting the first circuit board and the second circuit board and a connection portion are arranged around the connection portion. A multilayer circuit board characterized by having a high frequency material layer. The multilayer circuit board according to claim 1, wherein the connection portion contains a metal piece. The multilayer circuit board according to claim 2, wherein the metal piece has a pillar shape containing at least one metal of copper, gold, aluminum, and tungsten. The multilayer circuit board according to any one of claims 1 to 3, wherein the connecting portion includes at least one of a solder layer and a conductive paste layer. The multilayer circuit board according to any one of claims 1 to 4, wherein the high-frequency substrate and the high-frequency material layer are each composed of an insulating material having a dielectric loss of less than 0.01. The multilayer circuit board according to any one of claims 1 to 5, wherein an antenna capable of transmitting, receiving, or transmitting and receiving a high frequency signal is formed on the first circuit board. The multilayer circuit board according to claim 6, wherein the feeding line for feeding the at least one antenna is arranged in the same layer as the antenna. The multilayer circuit board according to claim 6 or 7, wherein the feeding line for supplying power to at least one of the antennas is not arranged in the same layer as the antenna. The multilayer circuit board according to any one of claims 6 to 8, wherein the antenna has a non-feeding element. The multilayer circuit board according to any one of claims 6 to 9, wherein a dielectric layer is laminated on the surface of the first circuit board on which the antenna is formed. The invention according to any one of claims 1 to 10, wherein an integrated circuit (IC) for processing a high frequency signal is mounted on at least one of the first circuit board and the second circuit board. Multi-layer circuit board.

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