JP2002198712A - Waveguide conversion board and high frequency module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a module that consists of a high frequency element package containing a high frequency element mounted on a wiring board and is connectable to a waveguide. SOLUTION: The module is characterized in the provision of a surface mount terminal A that is formed to a front side or a rear side of a dielectric board 1 and can be surface-mounted on a wiring board X1, a waveguide connection terminal C that is coupled with a waveguide on the front side or the rear side of the dielectric board 1, and a high frequency transmission line B interconnecting the surface mount terminal A and the waveguide connection terminal C. The surface mount terminal A has a signal conductor 2 and a ground conductor 3 placed at both sides of the conductor 2, and the waveguide connection terminal C has a ground conductor strip 12 that is formed on the front side or the rear side of the dielectric board 1 and has an inner diameter 13 substantially the same as that of a waveguide opening to which the strip 12 is connected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide conversion board which enables connection to an external element such as an antenna via a waveguide in a microwave or millimeter wave region, and a high-frequency module using the same. Regarding the improvement.

[0002]

2. Description of the Related Art In recent years, in the era of advanced information technology, it has been studied to utilize radio waves used for information transmission from a microwave region of 1 to 30 GHz to a millimeter wave region of 30 to 300 GHz. Application systems using millimeter wave radio waves, such as inter-vehicle radars, have also been proposed.

In such a high-frequency system, a waveguide is conventionally used to connect the module to an external element such as an antenna. Therefore, the module uses a microstrip line for forming an electronic circuit as a waveguide. A multi-chip module has been proposed in which all high-frequency elements are mounted and housed in a metal housing having an opening for connection, and are collectively hermetically sealed with a lid or the like.

FIG. 6 is a schematic cross-sectional view for explaining an example of the structure of a proposed multi-chip module. According to FIG. 6, the multi-chip module 60 includes a metal housing 61, a lid 62, and a plurality of high-frequency elements 6 therein.
3, a connection board 64, and a microstrip line board 65 for waveguide conversion. Each high frequency element 63
Is connected to the connection substrate 64 and the waveguide conversion microstrip line substrate 65 by wire bonding. A waveguide opening 66 is formed in the metal housing 61, and a dielectric window 67 is brazed to the waveguide opening 66 for hermetic sealing. The connection waveguide 68 is connected to the waveguide opening 66 of the metal housing 61.

In such a multi-chip module, since a large number of high-frequency elements are mounted on one metal housing, the size of the metal housing becomes large, and as a result, the deformation of the metal housing or the lid is caused. For example, there is a problem in the yield of hermetic sealing.

In order to solve such a problem, it has been proposed that a plurality of high-frequency elements are hermetically housed in a plurality of independent packages, and the plurality of packages are mounted on a wiring board to constitute a module. I have.

[0007]

However, in the case of a module in which high-frequency elements are individually housed in a package and individually mounted on a wiring board, the high-frequency transmission line used in the package is typically represented by a microstrip line. Therefore, it is necessary to form a waveguide conversion structure for connecting to an external element such as an antenna on a wiring board. Such a waveguide conversion structure is disclosed, for example, in JP-A-11-112209. In this structure, the microstrip line is converted into a waveguide via a slot and a matching dielectric. In order to obtain good conversion characteristics, the gap between the plurality of via-hole conductors forming the matching dielectric must be sufficiently narrower than the signal wavelength, and the dielectric loss tangent of the matching dielectric must also be small. When such a structure is applied to a normal wiring board, the conversion loss increases at a high frequency of 10 GHz or more due to the processing accuracy of the wiring board and the dielectric loss. There was a problem that transmission was not possible.

It is also conceivable to form a multi-chip module having a waveguide conversion structure as described above using a material which can be processed with high precision, such as ceramics, and has a small dielectric loss tangent. As a result, the size of the substrate is increased, and as in the case of using the above-described conventional metal housing,
There is a problem with hermetic sealing.

Further, in general, when a wiring board on which an electric element such as a semiconductor element is mounted and an external element such as an antenna element are connected, when the external element side is formed of a coplanar line terminal, a coplanar line structure is used. If connection terminals are provided and the external element has a waveguide structure, it is necessary to form a conversion part to the waveguide on the dielectric board side. Had to be changed appropriately.

Accordingly, the present invention provides a waveguide conversion board that can be mounted on the surface of a dielectric board and can be connected to a waveguide for a dielectric board of any structure.
It is an object of the present invention to provide a high-frequency module that can be simply and variously configured using the waveguide conversion substrate.

[0011]

The present inventor has made various studies in view of the above problems, and as a result, has found that a waveguide which can be surface-mounted on a wiring board having an electric element such as a semiconductor element mounted on the surface thereof. By separately providing a conversion board, any dielectric board can be made a board that can be connected to a waveguide, and signal transmission loss in conversion into a waveguide has been reduced.

That is, the waveguide conversion substrate of the present invention comprises: a dielectric substrate; surface-mounting terminals formed on the front or back surface of the dielectric substrate and capable of being surface-mounted on a wiring board; And a high-frequency transmission line connecting the surface mounting terminal and the waveguide connection terminal on the front surface or the back surface.

In this waveguide conversion board, the surface mounting terminal has a signal conductor and ground conductors disposed on both sides of the signal conductor, so that coupling with a normal coplanar line with small transmission loss can be realized. .

Further, the surface mount terminal is formed on the back side of the dielectric substrate, the high frequency transmission line is formed on the front side of the dielectric substrate, and the surface mount terminal and the high frequency transmission line are For example, it is preferable that a ground layer is formed inside the dielectric substrate, and the dielectric layer is electromagnetically coupled through a slot formed in the ground layer.

A desirable structure of the waveguide connection terminal is formed on the front or back surface of the dielectric substrate, and the waveguide connection terminal is substantially the same as the waveguide opening to be connected. Equipped with a ground conductor band having an inner diameter shape,
It is desirable that the ground conductor band is connected to a ground layer provided in the dielectric substrate by a plurality of via-hole conductors.

A high-frequency transmission line having an open end is formed on the surface of the dielectric substrate opposite to the surface on which the ground conductor band is formed, and a slot is formed in a portion of the ground layer corresponding to the waveguide opening. The high-frequency transmission line and the slot are electromagnetically coupled to each other, so that the high-frequency transmission line and the waveguide connected to the waveguide connection terminal can be coupled with low loss. .

Further, as another structure, a concave portion having a conductive layer attached to a side wall can be formed in an inner diameter portion of the ground conductor band in the waveguide connection terminal.

Further, the surface mounting terminal and the waveguide connection terminal can be on the same side or different sides of the dielectric substrate. Further, as another structure, a mounting portion for mounting an electric element such as a semiconductor element may be provided between the surface mounting terminal and the waveguide connection terminal. Note that the waveguide conversion board of the present invention is suitable when a signal having a frequency of 10 GHz or more is transmitted.

Further, in the high-frequency module of the present invention, a high-frequency transmission line is formed on the surface of a dielectric board, and the above-described high-frequency transmission line is formed on the surface of a wiring board having an electric element such as a semiconductor element mounted on the dielectric board. Wherein the waveguide conversion substrate is surface-mounted through the surface-mounting terminals, wherein the wiring board has a through hole formed of a conductor having a side wall formed on a dielectric board, In order that the waveguide connection terminal and the through-hole in the waveguide conversion board are aligned with each other, they are surface-mounted, and on the surface of the dielectric board opposite to the waveguide conversion board mounting side, It is also possible to provide a waveguide connection.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a waveguide conversion substrate of the present invention and a module using the same will be described in detail with reference to the drawings. FIG. 1 is a schematic plan view (a), a schematic bottom view (b), and a VV schematic cross-sectional view (c) for explaining an example of the waveguide conversion substrate of the present invention.

According to the waveguide converter board X ₁ in FIG. 1, on the back surface of the dielectric substrate 1, which can be surface-mounted on the wiring board by the ground conductor 3 formed signal conductor 2 and on both sides thereof Surface mount terminals A are formed. Note that surface mounting means a terminal that can be connected to wiring on a wiring board via a conductive material such as solder.

A ground layer 4 is formed inside the dielectric substrate 1, and the signal conductor 2 is connected to the dielectric substrate 1.
Together with the ground layer 4 formed inside the microstrip line. The ground conductor 3 of the surface mount terminal A is connected to the ground layer 4 by a through-hole conductor 5 and is kept at the same potential.

On the other hand, a signal conductor 6 having open ends at both ends is formed as a high-frequency transmission line B on the surface of the dielectric substrate 1, and forms a microstrip line together with the ground layer 4. The one end 6 a is electromagnetically coupled to the signal conductor 2 of the surface mount terminal A by a slot 7 formed in the ground layer 4.

On the other hand, a ground conductor band 12 having an inner diameter 13 substantially the same shape as the waveguide opening to be connected is formed on the back surface of the dielectric substrate 1 as the waveguide connection terminal portion C. The ground conductor band 12 is connected to the ground layer 4 provided in the dielectric substrate 1 by a plurality of via-hole conductors 11 provided at intervals less than １ ／ wavelength of the signal wavelength.

A slot 8 is formed in a portion of the ground layer 4 that matches the opening of the waveguide, and the other end 6b of the signal conductor 6 is electromagnetically coupled through the slot 8, and the slot 8 It is an excitation source for the tube connection terminal C. A dielectric 9 is arranged below the slot 8 for alignment with the waveguide. In some cases, an adjusting conductor 10 can be formed in the dielectric 9 to adjust the matching. The dielectric 9 is surrounded by via-hole conductors 11 in order to suppress signal leakage. The via-hole conductors 11 are the ground conductor bands 1 forming the waveguide connection terminals B on the back surface of the dielectric substrate 1.
2 are connected. And this ground conductor band 12
Is connected to a waveguide type connection port formed in the wiring board.

Further, on the back surface of the dielectric substrate 1, dummy conductors 14 may be provided around the dielectric substrate 1 in order to enhance the self-alignment effect at the time of surface mounting on the wiring board and enhance the connection strength after mounting. good.

With the above configuration, the signal transmitted from the surface mounting terminal A passes through the high-frequency transmission line B having the signal conductor 6, and passes through the slot 8 through the slot 8. C and can be transmitted to the waveguide. Conversely, the signal transmitted from the waveguide is converted into a high-frequency transmission line B at the waveguide connection terminal C and transmitted to the surface mount terminal A. As a result, the waveguide conversion substrate is surface-mounted on a wiring board, thereby forming a planar circuit such as a microstrip line formed on the wiring board and a waveguide for connecting an external element such as an antenna. Can be connected with low loss.

According to the waveguide conversion board X ₁ of FIG. 1, the surface mounting terminals A and the waveguide connection terminals C are formed on the same surface with respect to the dielectric substrate 1. The waveguide connection terminal C can be formed on a different surface. FIG.
3A is a schematic plan view (a), a schematic bottom view (b), and a WW schematic sectional view (c) for explaining an example thereof. In addition,
The component having a waveguide conversion substrate X ₁ same function denoted by the same reference numerals.

According to the waveguide conversion substrate X ₂ of FIG. 2, the signal conductor 2 and the ground conductors 3 formed on both sides thereof are formed on the back surface of the dielectric substrate 1, similarly to the waveguide conversion substrate X _1. A surface mounting terminal A that can be surface mounted on a wiring board according to the above is formed.

A ground layer 4 is formed inside the dielectric substrate 1, and the signal conductor 2 forms a microstrip line together with the ground layer 4 formed inside the dielectric substrate 1. The ground conductor 3 of the surface mount terminal A is connected to the ground layer 4 by the through-hole conductor 5.
And is kept at the same potential.

On the other hand, on the back surface of the dielectric substrate 1, a signal conductor 6 is formed as a high-frequency transmission line B, and a microstrip line is formed together with the ground layer 4. The signal conductor 6 is connected to the signal conductor 2 of the surface mounting terminal A.

On the other hand, a ground conductor band 12 having substantially the same inner diameter 13 as the waveguide opening to be connected is formed on the surface of the dielectric substrate 1 as the waveguide connection terminal portion C. The ground conductor band 12 is connected to the ground layer 4 provided in the dielectric substrate 1 by a plurality of via-hole conductors 11 provided at intervals smaller than 信号 wavelength of the signal wavelength.

A slot 7 is formed in a portion of the ground layer 4 which matches the opening of the waveguide. The open end 6a of the signal conductor 6 is electromagnetically coupled via the slot 7, and the slot 7 It is an excitation source for the tube connection terminal C. Above the slot 7, a dielectric 9 is arranged for matching with the waveguide. In some cases, an adjusting conductor 10 can be formed in the dielectric 9 to adjust the matching. The dielectric 9 is a via-hole conductor 11 for suppressing signal leakage.
The via-hole conductor 11 is surrounded by the ground conductor 1 forming the waveguide connection terminal B on the surface of the dielectric substrate 1.
2 are connected. The flange of the waveguide is connected to the ground conductor 12.

The above-mentioned waveguide conversion substrate X_TwoAccording to the surface
The signal transmitted from the mounting terminal A includes the signal conductor 6.
Via high-frequency transmission line B of microstrip line
And is coupled to the waveguide connection terminal C via the slot 7,
It becomes possible to transmit to a waveguide. Or a waveguide
The signal transmitted from the high-frequency transmission line at the waveguide connection terminal C
B and transmitted to the surface mount terminal A. The result
As a result, this waveguide conversion substrate X _TwoTo the wiring board.
This allows micro-strikes formed on the wiring board to be
Connect a planar circuit such as a lip line to an external element such as an antenna.
Low loss on the top side of the wiring board with the waveguide for connection
It is possible to connect with.

The waveguide conversion substrates X ₁ and X ₂ shown in FIGS.
Each of them has a surface mount terminal A, a waveguide connection terminal C, and a high-frequency transmission line B, but these waveguide conversion substrates require high strength because the waveguide is connected. Is done. As a result, it is desirable to increase the thickness of the waveguide conversion substrate. Further, according to the present invention, an electric element can be mounted on the waveguide conversion substrate. In FIG.
A schematic cross-sectional view of an example of a waveguide conversion substrate having such a function is shown.

According to the waveguide conversion substrate X ₃ of FIG. 3, FIG.
Of the inner diameter 13 portion of the ground conductor strip 12 at the waveguide connecting terminal C of the waveguide converter board X _1, it is those obtained by forming a recess 15 in which the conductor layer 16 is deposited and formed on the side wall,
This recess 15 substantially forms a waveguide. By providing such a concave portion 15, the thickness of the waveguide conversion substrate can be increased, and the strength of the substrate can be increased.

In this example, a connection terminal 1 connected to an electric element 17 such as a semiconductor element is provided in a high-frequency transmission line B located between a surface mounting terminal A and a waveguide connection terminal C.
8 and the electric element 1 mounted on the surface of the dielectric substrate 1
7 may be connected. Thereby, the waveguide conversion substrate X
It is possible to add a function as a substrate for mounting an electric element to ₃ , and furthermore, by forming a cavity with the lid 19, the mounted electric element 17 can be hermetically sealed. .

Next, an example of a high-frequency module using the waveguide conversion board of the present invention will be described with reference to FIG. _On the surface of the wiring board Y1, a high-frequency package Z containing a high-frequency element is mounted. According to the high-frequency package Z, the high-frequency elements 21 are mounted on the surface of the dielectric substrate 20, respectively, and are hermetically sealed by the lid 22. An input high-frequency transmission line 23a and an output high-frequency transmission line 23b are formed on the surface of the dielectric substrate 20, and one end of each of the lines 23a and 23b is connected to the high-frequency element 21, respectively. In addition, each track 2
The other ends of the dielectric substrates 3a and 23b are led out to the back surface of the dielectric substrate 20 through through-hole conductors 24a and 24b formed through the dielectric substrate 20.
Are connected to connection terminals 25a and 25b for connection to an external circuit formed on the back surface of. Also, the dielectric substrate 2
0, a ground layer 26 is formed, and each of the lines 23a and 23b together with the ground layer 26 forms a microstrip line type high-frequency transmission line. In addition, the through-hole conductor 24a of the internal ground layer 26,
An opening 27 is formed in the portion 24b, and is electrically non-contact with the through-hole conductors 24a and 24b.

The wiring board Y ₁ has a through-hole 31 having substantially the same cross-sectional shape as the opening of the waveguide 29 to which the conductor layer 30 is formed and connected on the side wall.
Then, the both end portions of the wiring board Y ₁ of the through hole 31, respectively connecting portions 32 and 33 are formed. Then, the waveguide 29 connected to an external element such as an antenna is fixed to the connection portion 33.

In order to connect such a wiring board Y ₁ and the waveguide 29, the high-frequency transmission line 28 formed on the surface of the wiring board Y ₁ and the high-frequency package Z are shown in FIG. surface mounted by soldering or the like according to waveguide substrate X ₁ surface mounting terminal a as. At that time, the waveguide converter board X ₁ of the waveguide connecting terminal C the connecting portion 32
And surface mounting. Further, the waveguide 29 can also be screwed against the wire board Y _1.

By mounting and sealing the high-frequency elements in individual packages in this manner, higher sealing reliability can be obtained as compared with a conventional multichip module. Further, by surface mounting waveguide conversion substrate X ₁ together with the high-frequency package Z equipped with high-frequency element individually to wiring board Y _1, is possible to achieve a high packing workability, the conversion loss to a small waveguide As a result, it is possible to achieve both a reduction in module mounting cost and good high-frequency characteristics.

[0042] In the high frequency module of Fig. 4 has been described modules to form a connecting portion of the high-frequency package Z mounting surface of the wiring board Y ₁ opposite to the waveguide, connecting portion of the waveguide, it is also possible in the same plane as the high-frequency package Z mounting surface of the wiring board Y _1. In such a case, FIG. 5 shows a schematic sectional view of an example of such a module.

[0043] According to the high frequency module of FIG. 5, the surface of the wiring board Y _2, similar to the RF module of FIG. 4, a high frequency device 21 is mounted, sealed frequency package Z is mounted, the wiring board Y _They are electrically connected to each other by a high-frequency transmission line 28 formed on the _two surfaces. Then, this wiring board Y ₂ of the surface, surface mount terminals A waveguide converter board X ₂ soldering or the like with respect to the waveguide conversion substrate X ₂ is a high frequency transmission line 28 as shown in FIG. 2 Surface mounted. Then, by attaching the flange of the waveguide 29 to the ground conductor strip 12 of the waveguide conversion terminal C of the waveguide converter board X _2, it can be connected to the waveguide at the upper surface side of the module. In this case, the waveguide 29, by fixing with screws to the wiring board Y _2, it is possible to stabilize the binding property between the waveguide and the converter board X _2.

The waveguide conversion board of the present invention and a high-frequency module using the same are 10 GHz or more,
This is particularly effective for transmission of a signal having a frequency of 0 GHz or more, and furthermore, 60 GHz or more.

[0045]

EXAMPLES The following experiments were conducted to confirm the effects of the present invention. First, two pieces of the waveguide conversion substrate shown in FIG. 1 were formed by ordinary laminating and co-firing techniques using a green sheet of alumina ceramic having a dielectric loss tangent of 0.0006 at 10 GHz and a tungsten metallized ink at 10 GHz. Produced. The surface conductor was plated with nickel and gold.

On the other hand, a coplanar line on which a waveguide conversion substrate can be mounted at both ends was formed by a copper foil on a fluorine resin board containing a glass cloth. A conductor band was formed in the waveguide connecting portion so that the side wall surrounded the through hole formed of a conductor and the through hole on both surfaces.

[0047] Solder paste is printed on the mounting portion on the coplanar line and the conductor band of the manufactured wiring board, and two waveguide conversion boards are mounted and reflow-processed to place the waveguide conversion board on the wiring board. Surface mounted. Waveguides are connected to the conductor bands on the back surface of the wiring board in the prepared evaluation sample, and the distance between one waveguide and the other waveguide is 10%.
The insertion loss at GHz was measured to estimate the conversion loss per conversion by the waveguide conversion substrate.

As a result, it was confirmed that the conversion loss per location at 10 GHz was about 0.3 dB, which was a sufficiently small loss for producing a practical module.

[0049]

As described above in detail, according to the waveguide conversion board of the present invention and the module using the same, by providing the waveguide conversion board with the surface mounting terminal and the waveguide connection terminal, A module that mounts and seals high-frequency elements in individual packages and that can be connected to the waveguide can be realized, improving sealing reliability and mounting workability of the module as a whole, and reducing loss of high-frequency signals can do.

[Brief description of the drawings]

FIG. 1 is a schematic plan view (a), a schematic bottom view (b), and a schematic cross-sectional view (V-V) for explaining an example of the waveguide conversion substrate of the present invention.

FIG. 2 is a schematic plan view (a), a schematic WW bottom view (b), and a schematic cross-sectional view (c) for explaining another example of the waveguide conversion substrate of the present invention.

FIG. 3 is a schematic sectional view for explaining still another example of the waveguide conversion substrate of the present invention.

FIG. 4 is a schematic sectional view for explaining an example of the high-frequency module of the present invention.

FIG. 5 is a schematic sectional view for explaining another example of the high-frequency module of the present invention.

FIG. 6 is a schematic sectional view for explaining the structure of a conventional multi-chip type high-frequency module.

[Explanation of symbols]

A surface mounting terminal B high-frequency transmission line C waveguide connection terminal X _1, X _2, X ₃ waveguide connection board X1 dielectric substrate 2 signal conductors 3 ground conductor 4 ground layer 5 through hole conductor 6 signal conductors 7 and 8 Slot 9 Dielectric 10 Adjusting conductor 11 Via hole conductor 12 Ground conductor band 13 Inner diameter

Claims (15)

[Claims] 1. A dielectric substrate, a surface mounting terminal formed on a front or back surface of the dielectric substrate and mountable on a wiring board, and a waveguide coupled to the front or back surface of the dielectric substrate. A waveguide conversion substrate, comprising: a possible waveguide connection terminal; and a high-frequency transmission line connecting the surface mounting terminal and the waveguide connection terminal. 2. A dielectric substrate, a surface mounting terminal formed on the front or back surface of the dielectric substrate, and surface mountable on a wiring board, and coupled to a waveguide on the front or back surface of the dielectric substrate. A possible waveguide connection terminal, a mounting part for mounting an electric element such as a semiconductor element, and a high-frequency transmission line connecting the mounting part with the surface mounting terminal and the waveguide connection terminal are provided. A waveguide conversion board characterized by the above-mentioned. 3. The waveguide conversion substrate according to claim 1, wherein a ground layer is formed inside said dielectric substrate. 4. The device according to claim 1, wherein the surface mounting terminal has a signal conductor and ground conductors disposed on both sides of the signal conductor, and the ground conductor is connected to a ground layer inside the dielectric substrate. 4. The waveguide conversion substrate according to claim 1. 5. The high frequency transmission line, wherein the surface mount terminal is formed on the back side of the dielectric substrate, and the high frequency transmission line is formed on the front side of the dielectric substrate. The waveguide conversion substrate according to any one of claims 1 to 4, wherein the substrate is electromagnetically coupled. 6. The waveguide according to claim 3, wherein the surface mount terminal and the high-frequency transmission line are electromagnetically coupled via a slot formed in the ground layer. Conversion board. 7. The waveguide connection terminal is formed on a front surface or a back surface of the dielectric substrate, and the waveguide connection terminal has substantially the same inner diameter shape as a waveguide opening to be connected. 7. The waveguide conversion substrate according to claim 1, further comprising a ground conductor band having the same. 8. The waveguide conversion board according to claim 7, wherein said ground conductor band is connected to a ground layer provided in said dielectric substrate by a plurality of via-hole conductors. 9. A high-frequency transmission line having an open end is formed on the surface of the dielectric substrate opposite to the ground conductor band forming surface, and a slot is formed in a portion of the ground layer that matches the waveguide opening. 9. The waveguide conversion board according to claim 8, wherein the waveguide conversion board is formed and the high-frequency transmission line and the slot are electromagnetically coupled. 10. The conductor according to claim 7, wherein a recess having a conductor layer attached to a side wall is formed in an inner diameter portion of the ground conductor band in the waveguide connection terminal. Wave tube conversion board. 11. The waveguide according to claim 1, wherein the surface mounting terminal and the waveguide connection terminal are provided on the same surface of the dielectric substrate. Tube conversion board. 12. The waveguide according to claim 1, wherein said surface mount terminal and said waveguide connection terminal are provided on different surfaces of said dielectric substrate. Conversion board. 13. The waveguide conversion board according to claim 1, wherein a signal having a frequency of 10 GHz or more is transmitted. 14. The wiring board according to claim 1, wherein a high-frequency transmission line is formed on the surface of the dielectric board, and an electric element such as a semiconductor element is mounted on the dielectric board. A high-frequency module, wherein the waveguide conversion board according to any one of the above is surface-mounted via the surface mounting terminal. 15. A dielectric board in the wiring board, wherein a through hole having a side wall made of a conductor is formed, and the surface is mounted so that the waveguide connection terminal in the waveguide conversion board and the through hole are aligned. 15. The high-frequency module according to claim 14, further comprising a waveguide connecting portion on a surface of the dielectric board opposite to a side on which the waveguide conversion board is mounted.