JP7706949B2 - Circuit board and high frequency module - Google Patents

Description

This disclosure relates to interlayer power supply technology in circuit boards.

When supplying power to the opposite side of a circuit board, it is common to use a single via conductor. However, when the radio waves are short, such as in the millimeter wave band, there is a problem in that it is difficult to supply high-frequency signals to the opposite side of the circuit board.

To solve this problem, an interlayer power supply technology for millimeter-wave band high-frequency signals has been proposed (see, for example, Patent Document 1). In Patent Document 1, the length of the via conductor is set within a predetermined range with respect to the wavelength λ of the high-frequency signal, making it possible to supply a millimeter-wave band high-frequency signal. For this reason, Patent Document 1 has the problem that the interlayer thickness is limited by the length of the via conductor.

JP 2003-204209 A

Therefore, the purpose of this disclosure is to make it possible to supply high-frequency signals to circuit boards with any inter-layer thickness.

The circuit board of the present disclosure includes:
a first conductor line disposed on a dielectric substrate;
a via conductor penetrating a dielectric substrate on which the first conductor line is disposed;
a second conductor line disposed on a surface of a dielectric substrate different from the surface of the first conductor line and connected to the via conductor;
a plurality of through conductors disposed around the via conductor and penetrating the same dielectric substrate as the dielectric substrate penetrated by the via conductor;
a matching unit connected to at least one of the first conductor line and the second conductor line;
Equipped with.

The high-frequency module of the present disclosure includes:
A high-frequency module using a circuit board according to the present disclosure,
an antenna element using the first conductor line or the second conductor line;
a signal processing unit that generates a high frequency signal to be supplied to the antenna element;
Equipped with
The via conductor supplies a high frequency signal from the signal processing unit to the antenna element.

The present disclosure relates to a circuit board in which a plurality of through conductors are arranged around a via conductor, and a matching device is arranged on at least one of the first conductor line and the second conductor line, so that a high-frequency signal can be supplied even to a circuit board having any interlayer thickness.

3A and 3B are plan views of a circuit board, in which FIG. 2 is an example of the A-A' cross-sectional structure of a circuit board. 1 illustrates an example of the configuration of a circuit board according to the present disclosure. 13 is an example of an arrangement of a plurality of through conductors. 13 is an example of an arrangement of a plurality of through conductors. 13 is an example of an arrangement of a plurality of through conductors. 4 is an example of an arrangement of through conductors according to an embodiment. This is an example of the B-B' cross-sectional configuration. This is an example of the C-C' cross-sectional configuration. 1 is an example of a manufacturing process for a circuit board. 1 is an example of a manufacturing process for a circuit board. 1 is an example of a manufacturing process for a circuit board. 13 is a cross-sectional configuration example of a circuit board when there is a misalignment between a second layer and a third layer of a dielectric substrate. 1 is an example of a pattern cut-out portion formed in a second layer and a third layer of a dielectric substrate. 4 is an example of a cross-sectional configuration of a circuit board when pattern cut-out portions of a second layer and a third layer are enlarged. 13A and 13B are comparative examples of output levels to the opposite surface, in which (a) shows a case where the pattern cut-out portion is not enlarged, and (b) shows a case where the pattern cut-out portion is enlarged. 2 is an example of an antenna substrate according to an embodiment.

The following describes in detail the embodiments of the present disclosure with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings are mutually identical.

(First embodiment)
1 and 2 show an example of a circuit board according to the present embodiment. The circuit board according to the present embodiment includes a dielectric substrate 11, a conductor line 12 disposed on the upper surface of the dielectric substrate 11, and a conductor line 14 disposed on the lower surface of the dielectric substrate 11. The conductor lines 12 and 14 are connected by a via conductor 16 that penetrates the dielectric substrate 11.

In this embodiment, an example is shown in which the dielectric substrate 11 includes a first layer 11-1 to a fourth layer 11-4, the conductor line 12 is disposed on the upper surface of the first layer 11-1, and the conductor line 14 is disposed on the lower surface of the fourth layer 11-4. The conductor lines 12 and 14 function as first and second conductor lines, respectively. The first layer 11-1 and the fourth layer 11-4 function as first and second dielectric substrates, respectively.

At least one of the conductor lines 12 and 14 is connected to an antenna element or is used in an antenna element. For example, the conductor line 12 functions as a power feed line arranged on the component mounting surface, the conductor line 14 functions as an antenna element, and the via conductor 16 functions as a power feed conductor. This makes it possible to configure an antenna board that feeds power from the component mounting surface to an antenna element arranged on the opposite surface. In this configuration, when the radio waves are short, such as in the millimeter wave band, it is difficult for the high-frequency signal from the conductor line 12 to be fed to the conductor line 14 using only the via conductor 16.

As shown in FIG. 3, the circuit board of this embodiment includes a plurality of through conductors 20 that are arranged around the via conductor 16 and penetrate the dielectric substrate 11. The plurality of through conductors 20 are arranged in point symmetry with the via conductor 16 as the center. In this manner, the present disclosure employs a structure that mimics a coaxial cable by arranging a plurality of through conductors 20 around the via conductor 16. This allows the circuit board of the present disclosure to secure a waveguide for power supply and function as a power supply converter having a coaxial cable shape.

For example, as shown in Fig. 4, six through conductors 22 to 24, 26 to 28 are arranged on a concentric circle of radius φ ₂₀ centered on the via conductor 16 so as to surround the via conductor 16. The through conductors 22 to 24, 26 to 28, like the via conductor 16, penetrate all of the first layer 11-1 to the fourth layer 11-4. Therefore, the through conductors 22 to 24, 26 to 28 are arranged on the concentric circle of radius φ ₂₀ at positions that do not overlap with the conductor line 12. The intervals between the through conductors 22 to 24 and the intervals between the through conductors 26 to 28 are arbitrary, but for example, they are arranged at equal intervals so as to be point symmetrical with the via conductor 16 at the center.

For example, as shown in Fig. 5, eight through conductors 21 to 28 are arranged on a concentric circle of radius φ ₂₀ centered on the via conductor 16 so as to surround the via conductor 16. In the example of Fig. 5, a plurality of through conductors 21 and 25 are provided which are arranged at positions overlapping with the conductor line 12. In this case, the through conductors 21 and 25 penetrate only the second layer 11-2 and the third layer 11-3 which are arranged between the first layer 11-1 and the fourth layer 11-4 as shown in Fig. 6.

In this way, the present disclosure provides a waveguide for power supply by arranging multiple through conductors around the via conductor 16. In this embodiment, matching devices 12M and 14M are further provided on the extensions of the conductor lines 12 and 14 in order to adjust the transmission characteristics of the high-frequency signal in the via conductor 16. In order to adjust the transmission characteristics of the high-frequency signal in the via conductor 16, the circuit board of the present disclosure adjusts the length of the matching devices 12M and 14M, the line width of the conductor line 12 that is the power supply source, and the line width of the conductor line 14 that is the power supply destination. This makes it possible for the present disclosure to supply power to the opposite surface using the via conductor 16.

Figure 7 shows an example of the arrangement of the through conductors in this embodiment. In this example, the through conductors 31 and 32 are arranged along the conductor line 12, and the through conductors 33 to 35 are arranged around the matching units 12M and 14M. Figures 8 and 9 show an example of the B-B' cross-sectional configuration and the C-C' cross-sectional configuration. As shown in Figure 8, the through conductors 33 to 35 penetrate from the first layer 11-1 to the fourth layer 11-4 of the dielectric substrate 11. As shown in Figure 9, the through conductor 32 penetrates only the first layer 11-1 and the fourth layer 11-4 of the dielectric substrate 11. Like the through conductor 32, the through conductor 31 also penetrates only the first layer 11-1 and the fourth layer 11-4 of the dielectric substrate 11.

As described above, the circuit board of this embodiment forms a coaxial cable-shaped converter by arranging multiple through conductors around the via conductor 16, and provides matching devices 12M and 14M on the conductor lines 12 and 14. This allows the circuit board of this embodiment to supply high-frequency signals to a circuit board having any interlayer thickness.

In this embodiment, an example is shown in which matching devices 12M and 14M are provided on both conductor lines 12 and 14, but it is not necessary to provide both matching devices 12M and 14M, and the action and effect of the present disclosure can be obtained even if only one of matching devices 12M and 14M is provided.

In this embodiment, an example is shown in which power is supplied from the component mounting surface to the opposite surface of the circuit board, but the present disclosure can be applied to any circuit board that supplies high-frequency signals using via conductors 16. For example, as described below, antenna elements may be formed on both sides of the dielectric substrate 11.

In addition, in this embodiment, an example has been shown in which the via conductor 16 and the through conductors 22 to 24, 26 to 28 penetrate from the first layer 11-1 to the fourth layer 11-4, but the present disclosure is not limited to this. For example, the conductor lines 12 and 14 can be arranged on any different planes, and the via conductor 16 can be of any length that can connect the conductor lines 12 and 14. Therefore, the via conductor 16 and the through conductors 22 to 24, 26 to 28 only need to penetrate the same dielectric substrate, and may be configured to penetrate, for example, from the first layer 11-1 to the third layer 11-3, but not the fourth layer 11-4. In this case, the through conductors 21 and 25 penetrate only the second layer 11-2.

In this embodiment, an example of the dielectric substrate 11 is shown having four layers, the first layer to the fourth layer, but the number of layers of the dielectric substrate provided in the circuit board of the present disclosure can be any number equal to or greater than one. For example, the dielectric substrate disposed between the first layer 11-1 and the fourth layer 11-4 may have three or more layers. In this case, the three or more layers of dielectric substrate disposed between the first layer 11-1 and the fourth layer 11-4 function as a third dielectric substrate, and the through conductors 21 and 25 penetrate any number of the third dielectric substrates.

Second Embodiment
When arranging the via conductors 16 described in the first embodiment, the first layer 11-1 to the fourth layer 11-4 are fabricated (FIG. 10), the second layer 11-2 and the third layer 11-3 are laminated with the prepreg 13, and the through conductors 21 and 25 that penetrate these layers are formed (FIG. 11). Then, the first layer 11-1 to the fourth layer 11-4 are all laminated together, and the via conductors 16 are arranged (FIG. 12).

Before laminating the second layer 11-2 and the third layer 11-3 with the prepreg 13, as shown in FIG. 11, regions (called pattern cutouts) that do not have a conductor pattern made of a copper foil layer or the like are formed on the second layer 11-2 and the third layer 11-3. For example, a pattern cutout 62-1 is formed on the upper surface of the second layer 11-2, a pattern cutout 62 is formed on the lower surface of the second layer 11-2 and the upper surface of the third layer 11-3, and a pattern cutout 62-4 is formed on the lower surface of the third layer 11-3. In addition, before laminating all of the first layer 11-1 to the fourth layer 11-4, a pattern cutout 61 is formed on the lower surface of the first layer 11-1, and a pattern cutout 63 is formed on the upper surface of the fourth layer 11-4.

If there is a misalignment between the second layer 11-2 and the third layer 11-3 when the first layer 11-1 to the fourth layer 11-4 are bonded together, as shown in Fig. 13, a misalignment ΔP occurs between the pattern cut-out 61 on the lower surface of the first layer 11-1 and the pattern cut-out 62-1 on the upper surface of the second layer 11-2, and a misalignment ΔP occurs between the pattern cut-out 63 on the upper surface of the fourth layer 11-4 and the pattern cut-out 62-4 on the lower surface of the third layer 11-3. This misalignment ΔP causes distortion of the power supply path. Therefore, in the circuit board of this embodiment, the diameter φ ₆₂ of the pattern cut-outs 62-1 and 62-4 is enlarged.

FIG. 14 shows an example of the pattern cutouts 62-1 and 62-4. In this embodiment, the pattern cutouts 62-1 and 62-4 are formed with a margin relative to the diameter of the via conductor 16. For example, the difference between the inner diameter φ ₆₂ of the pattern cutouts 62-1 and 62-4 and the diameter of the via conductor 16 is larger than the manufacturing error of the circuit board. The pattern cutouts 62-1 and 62-4 may overlap the through conductors 22 to 24, 26 to 28. That is, at least a part or all of the through conductors 22 to 24, 26 to 28 may be disposed in the pattern cutouts 62-1 and 62-4. In this case, as shown in FIG. 15, the positions of the through conductors 21 and 25 overlap the pattern cutouts 62-1 and 62-4, so the through conductors 21 and 25 are not disposed.

Figure 16 shows comparative examples of output levels. Figure 16(a) shows a case where the through conductors 21 and 25 are arranged on the second layer 11-2 and the third layer 11-3, and the pattern cutouts 62-1 and 62-4 are not enlarged. Figure 16(b) shows a case where the pattern cutouts 62-1 and 62-4 are enlarged, and the through conductors 21 and 25 are not arranged. In both cases, the second layer 11-2 and the third layer 11-3 are shifted by -200 μm, -100 μm, 0 μm, 100 μm, and 200 μm relative to the first layer 11-1 and the fourth layer 11-4. When the pattern cutouts 62-1 and 62-4 are not enlarged, the difference in output level was about 2 dB, as shown in Figure 16(a). When the pattern cutouts 62-1 and 62-4 are enlarged, the difference in output level was about 0.6 dB, as shown in Figure 16(b).

Therefore, by enlarging the diameter _φ62 of the pattern cut-out portions 62-1 and 62-4, it is possible to reduce the degree of deformation of the power supply path caused by misalignment of the first layer 11-1 to the fourth layer 11-4, and as a result, it is possible to significantly reduce the variation in output level due to misalignment of the interlayer bonding.

Third Embodiment
The via conductor 16 of the present disclosure can feed power to the opposite surface and can also be used as a two-branch distributor, so the circuit board of the present disclosure can be applied to an antenna distributor.

Figure 17 shows an example of an antenna board of this embodiment. The antenna board of this embodiment includes a plurality of conductor lines 12, 14 and via conductors 16, and a plurality of antenna elements 70 are formed on the same surface of the dielectric board 11 using the conductor lines 12. Each antenna element 70 is connected to a conductor line 14 on the opposite surface of the dielectric board 11 using a via conductor 16 that penetrates the dielectric board 11. This forms a centrally fed array antenna with the via conductor 16 located in the center.

In the present disclosure, the through conductors 22-24, 26-28 are arranged in a coaxial cable shape, and a matching device 14M is arranged on the opposite side (not shown), so that power is fed from a feeder line equipped with a matching device. As a result, in this embodiment, a two-branch feeder can be realized in a small space. Therefore, in the present disclosure, it is possible to design the spacing _D70 of the antenna elements 70 to be less than one wavelength of the transmission and reception wavelength λ of the antenna elements 70, for example, a narrow spacing of about λ/2.

The circuit board of the present disclosure described above can be applied to any high-frequency module in which a signal processing unit such as an MMIC (Monolithic Microwave Integrated Circuit) is arranged on the component mounting surface and a high-frequency signal from the signal processing unit is supplied to the conductor lines 12 and 14.

The processing in the signal processing unit is arbitrary. For example, the signal processing unit generates a high-frequency signal and uses it to transmit and receive signals via the antenna element. This makes it possible to configure a transmission and reception module. For example, the signal processing unit generates a transmission wave for radar and supplies it to a transmitting antenna, and detects an object using the reflected wave from the object received by the receiving antenna. This makes it possible to configure a radar module. In addition, the high-frequency module of the present disclosure may be any module that supplies high-frequency signals to the conductor lines 12 and 14.

Here, the high-frequency signal may be a millimeter-wave band high-frequency signal of 24 GHz, 28 GHz, 36 GHz, 39 GHz, 60 GHz, 76 GHz, 79 GHz, etc., or a high-frequency signal of any frequency that can be transmitted and received using an antenna.

This disclosure can be applied to the information and communications industry.

11: dielectric substrate 12, 14: conductor line 13: prepreg 16: via conductor 17, 18: conductor 19: ground conductor 20, 21-28, 31-35: through conductor 41, 42: lands 61, 62-1, 62-4, 63: pattern cut-out portion 70: antenna element

Claims (7)

a dielectric substrate including a third dielectric substrate disposed between a first dielectric substrate and a second dielectric substrate;
a first conductor line disposed on the first dielectric substrate;
a second conductor line disposed on the second dielectric substrate;
a via conductor that passes through the dielectric substrate and connects the first conductor line and the second conductor line;
a first plurality of through conductors arranged on a concentric circle centered on the via conductor and penetrating the dielectric substrate;
a second plurality of through conductors penetrating only the third dielectric substrate at positions where the concentric circles and the first conductor line or the second conductor line overlap ;
a matching unit connected to at least one of the first conductor line and the second conductor line;
A circuit board comprising : a conductor arranged on a side of the first conductor line of the third dielectric substrate and a conductor arranged on a side of the second conductor line of the third dielectric substrate each include a pattern cut-out portion in which no conductor is arranged, at a position where the via conductor is arranged;
a difference between an inner diameter of the pattern cut-out portion and a diameter of the via conductor is greater than a manufacturing error of the circuit board;
The circuit board according to claim 1 . the pattern cut-out portion formed in the third dielectric substrate and the first plurality of through conductors penetrating the first dielectric substrate and the second dielectric substrate overlap each other;
The circuit board according to claim 2 . the first plurality of through conductors are arranged point symmetrically with respect to the via conductor;
The circuit board according to claim 1 or 2 . a plurality of the first conductor lines, a plurality of the second conductor lines, and a plurality of the via conductors;
A plurality of antenna elements are configured using the first conductor line or the second conductor line,
The spacing between the antenna elements is less than one wavelength of the transmission or reception wavelength of each antenna element.
5. The circuit board according to claim 1. The transmission wavelength or the reception wavelength is a wavelength included in the millimeter wave band.
The circuit board according to claim 5 . A high-frequency module using the circuit board according to any one of claims 1 to 6 ,
an antenna element using the first conductor line or the second conductor line;
a signal processing unit that generates a high frequency signal to be supplied to the antenna element;
Equipped with
The via conductor supplies a high-frequency signal from the signal processing unit to the antenna element.
High frequency module.

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