Wireless communication module

Abstract

To provide a radio communication module which can reduce the transmission loss of a high frequency signal at a connection part between the through hole of a mounting substrate and an antenna substrate or a high frequency integrated circuit.SOLUTION: A radio communication module 1 includes: a mounting substrate 10 having a signal through hole 11, through which a high frequency signal is transmitted, and a plurality of ground through holes 12 set to have ground potential, formed from a first surface 10a toward a second surface 10b; an RFIC 30 mounted on the first surface 10a side; a signal metal terminal 31 which connects one end of the signal through hole 11, located on the first surface 10a side, to the RFIC 30; and a plurality of ground metal terminals 32 which are provided between the first surface 10a and the RFIC 30 and of which centers are positioned inside a virtual circle around the signal through hole 11 which passes the centers of the ground through holes 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wireless communication module. [Background technology]

[0002] In recent years, there has been active development of wireless communication modules that perform wireless communication using high-frequency signals such as millimeter waves. One such wireless communication module has an antenna board and a radio-frequency integrated circuit (RFIC: Radio Frequency Integrated Circuit) mounted on both sides of a mounting board and electrically connected to each other via through-holes in the mounting board. There is also a wireless communication module in which a radio-frequency integrated circuit is mounted on one side of a mounting board on which an antenna element is formed, and the antenna element and the radio-frequency integrated circuit are electrically connected to each other via through-holes in the mounting board.

[0003] The following Patent Document 1 discloses a printed wiring board in which a through hole (signal through hole) through which a high frequency signal is transmitted is surrounded by a large number of through holes at ground potential (ground through holes) to reduce transmission loss. The following Patent Document 2 discloses a technique for connecting a through hole formed in a printed wiring board and an IC mounted on the printed wiring board via a wiring pattern of the printed wiring board. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-73891 A [Patent Document 2] JP 2000-114729 A Summary of the Invention [Problem to be solved by the invention]

[0005] By the way, by using the technology disclosed in the above-mentioned Patent Document 1, it is possible to reduce the transmission loss of a high-frequency signal transmitted through a signal through-hole formed in a printed wiring board. However, neither of the technologies disclosed in the above-mentioned Patent Documents 1 and 2 takes into consideration the transmission loss occurring at the connection between the printed wiring board and the IC. For this reason, there is a problem that the reflection of the high-frequency signal increases due to impedance mismatch at the connection between the printed wiring board and the IC, and the transmission loss of the high-frequency signal increases. This problem occurs whether the through-hole (via) connected to the IC penetrates the printed wiring board (through-hole via) or does not penetrate the printed wiring board (blind via).

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a wireless communication module that can reduce transmission loss of high-frequency signals at the connection between a via in a mounting substrate and an antenna substrate or a high-frequency integrated circuit. [Means for solving the problem]

[0007] In order to solve the above problem, a wireless communication module (1 to 3) according to one embodiment of the present invention comprises: a mounting substrate (10) on which a signal via (11) through which a high-frequency signal is transmitted extending from a first surface (10a) toward a second surface (10b) that is the surface opposite to the first surface, and a plurality of ground vias (12) that are at ground potential and extend from the first surface toward the second surface and are provided at different circumferential positions from each other about the signal via; a first mounting component (30 or 20) mounted on the first surface side; a first signal metal terminal (31) that connects one end of the signal via located on the first surface side to the first mounting component; and a plurality of first ground metal terminals (32) that are provided between the first surface and the first mounting component so that their centers are located inside a virtual circle (VC) that is centered on the signal via and passes through the center of the ground via.

[0008] In a wireless communication module according to one aspect of the present invention, a first signal metal terminal that connects one end of a signal via formed on the mounting board to the first mounting component is surrounded by a plurality of ground metal terminals between the mounting board and the first mounting component. This achieves impedance matching at the connection portion where the mounting board and the first mounting component are connected, thereby reducing the reflection of high-frequency signals at the connection portion. As a result, the transmission loss of high-frequency signals at the connection portion can be reduced.

[0009] In addition, in the wireless communication module according to one aspect of the present invention, the first signal metal terminal and the first ground metal terminal are arranged to form an impedance-matched pseudo-coaxial structure.

[0010] In addition, in a wireless communication module according to an aspect of the present invention, the first signal metal terminal and the first ground metal terminal are surrounded by a material having a dielectric constant lower than that of the mounting substrate.

[0011] In a wireless communication module according to an aspect of the present invention, the first ground metal terminal is connected to either the first surface or the first mounting component facing the first surface.

[0012] In addition, in the wireless communication module according to one aspect of the present invention, the signal vias and the ground vias are arranged to form an impedance-matched pseudo-coaxial structure.

[0013] In addition, a wireless communication module according to one embodiment of the present invention includes a second mounting component (20 or 30) mounted on the second surface side, in which the signal via and the ground via penetrate from the first surface to the second surface, a second signal metal terminal (21) connecting the other end of the signal via located on the second surface side to the second mounting component, and a plurality of second ground metal terminals (22) arranged between the second surface and the second mounting component with their centers located inside the imaginary circle.

[0014] In a wireless communication module according to one aspect of the present invention, the first mounting component is either an antenna board or a high-frequency integrated circuit, and the second mounting component is the other of the antenna board and the high-frequency integrated circuit. Effect of the Invention

[0015] According to the present invention, it is possible to reduce the transmission loss of high frequency signals at the connection between the via of the mounting board and the antenna board or the high frequency integrated circuit. [Brief description of the drawings]

[0016] [Figure 1] 1 is a side cross-sectional view showing a configuration of a main part of a wireless communication module according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Diagram 3] 2 is a plan view showing an example of a ground pattern formed on a mounting board in one embodiment of the present invention; FIG. [Figure 4] 11 is a side cross-sectional view showing a configuration of a main part of a wireless communication module according to a first modified example. FIG. [Diagram 5] 5 is a cross-sectional view taken along line BB in FIG. 4. [Figure 6] 13 is a side cross-sectional view showing a configuration of a main part of a wireless communication module according to a second modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, a wireless communication module according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the characteristics easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality. Furthermore, the present invention is not limited to the following embodiments.

[0018] Fig. 1 is a side cross-sectional view showing a main configuration of a wireless communication module according to an embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. As shown in Fig. 1, the wireless communication module 1 of this embodiment includes a mounting substrate 10, an antenna substrate 20 (second mounting component or first mounting component), and an RFIC (radio frequency integrated circuit) 30 (first mounting component or second mounting component), and transmits and receives high-frequency signals such as millimeter waves having a frequency of about 50 to 70 [GHz]. The wireless communication module 1 may only transmit or only receive high-frequency signals.

[0019] <Mounting board> The mounting substrate 10 is a substrate on which components such as the antenna substrate 20 and the RFIC 30 are mounted. The mounting substrate 10 may be made of a material having a larger dielectric tangent (a material having a larger loss of high-frequency signals) than the antenna substrate 20. Examples of the material that can be used for the mounting substrate 10 include glass epoxy, polyimide, liquid crystal polymer (LCP), and polyphenylene ether (PPE) resin. By using glass epoxy as the material for the mounting substrate 10, it is possible to reduce costs and obtain a certain degree of transmission characteristics.

[0020] It is desirable that the thickness of the mounting substrate 10 is as thin as possible. This is to reduce the transmission loss of high-frequency signals and to enable the formation of fine through-holes using a drill with a smaller diameter. For example, when forming fine through-holes with a diameter of about 0.1 mm, it is desirable to use a mounting substrate 10 with a thickness of about 1.0 mm.

[0021] A signal through hole 11 (signal via) and a ground through hole 12 (ground via) are formed in the mounting board 10. The signal through hole 11 and the ground through hole 12 penetrate from the first surface 10a of the mounting board 10 to the second surface 10b, which is the surface opposite to the first surface 10a. In other words, the signal through hole 11 and the ground through hole 12 are through-hole vias.

[0022] The signal through hole 11 is a through hole for transmitting a high-frequency signal. Although only one signal through hole 11 is shown in Fig. 1 for the sake of simplicity, a plurality of signal through holes 11 may be provided in the mounting board 10.

[0023] The ground through holes 12 are through holes at ground potential, and a plurality of ground through holes 12 are provided for the same signal through hole 11 (see FIG. 2). As shown in FIG. 2, the plurality of ground through holes 12 are provided at different positions in the circumferential direction centered on the signal through hole 11 in a plan view seen from the thickness direction of the mounting board 10. The plurality of ground through holes 12 may be arranged, for example, at equal intervals in the circumferential direction centered on the signal through hole 11. In this embodiment, the number of ground through holes 12 corresponding to the same signal through hole 11 is four. These four ground through holes 12 are positioned at 90 degrees apart in the circumferential direction centered on the signal through hole 11. It is preferable that the number of ground through holes 12 for the same signal through hole 11 is four or more.

[0024] The signal through-hole 11 and the ground through-hole 12 are arranged to form an impedance-matched pseudo-coaxial structure. Here, the impedance-matched pseudo-coaxial structure refers to a structure in which, when considering a coaxial structure with the signal through-hole 11 as the central conductor, the ground through-hole 12 is arranged on or near a virtual circle VC (see FIG. 2) where a ground conductor surrounding the central conductor should be arranged. The positional deviation of the ground through-hole 12 from the virtual circle VC is permissible if the impedance error is within a range of about ±10 [Ω], for example. With such a structure, the transmission loss of a high-frequency signal transmitted through the signal through-hole 11 can be reduced.

[0025] Here, the characteristic impedance Z0 of the coaxial structure is expressed by the following formula (1): In the following formula (1), d is the diameter (outer diameter) of the inner conductor, D is the diameter (inner diameter) of the outer conductor, and ε ris the relative dielectric constant of the material between the inner conductor and the outer conductor. From the following equation (1), the relative dielectric constant ε r It can be seen that when is small, it is possible to adjust the characteristic impedance by increasing the ratio of the diameters of the outer conductor and the inner conductor (D / d).

[0026]

number

[0027] The above formula (1) can be approximately applied to a pseudo-coaxial structure formed by the signal through-hole 11 and the ground through-hole 12. Specifically, if the diameter of the signal through-hole 11 is the diameter d of the inner conductor and the diameter of the imaginary circle VC shown in FIG. 2 is the diameter D of the outer conductor, the characteristic impedance of the pseudo-coaxial structure can be calculated from the above formula (1). For example, when the dielectric constant of the mounting board 10 is 4.54, in order to make the characteristic impedance of the pseudo-coaxial structure (in which the number of ground through-holes 12 is four) shown in FIG. 1 and FIG. 2 50 [Ω], the ratio of the diameters of the outer conductor and the inner conductor (D / d) should be 5.625. This value was calculated by analysis using the finite element method.

[0028] The diameter of the signal through-hole 11 and the ground through-hole 12 is generally about 0.1 mm or more, and is preferably about 0.2 mm or less in consideration of miniaturization. The signal through-hole 11 and the ground through-hole 12 are preferably formed by any of a conductor pin, a conductor wire, metal plating, a conductive paste, etc., but are not limited thereto. Examples of conductors used for the signal through-hole 11 and the ground through-hole 12 include metals such as copper, silver, gold, alloys, and carbon. The shapes of the signal through-hole 11 and the ground through-hole 12 are not particularly limited, but examples thereof include pin-shaped, linear, layered, particulate, scale-shaped, fibrous, nanotube, etc.

[0029] 1 and 2, it is preferable that an electrode pad is formed on each end of the signal through hole 11. In other words, it is preferable that the signal through hole 11 has a so-called pad-on-via structure. The ground through hole 12 may also have a so-called pad-on-via structure. By using such a pad-on-via structure, the transmission distance of the high-frequency signal can be shortened, and therefore the transmission loss of the high-frequency signal can be reduced.

[0030] 3 is a plan view showing an example of a ground pattern formed on a mounting board in one embodiment of the present invention. As shown in FIG. 3, the ground pattern 13 is formed in a plate or film shape extending in a direction along the first surface 10a or the second surface 10b of the mounting board 10. The ground pattern 13 is electrically connected to the ground through hole 12 and reinforces the ground through hole 12. The ground pattern 13 has an opening 13a penetrating in its thickness direction, and the signal through hole 11 is located inside the opening 13a. This electrically insulates the ground pattern 13 from the signal through hole 11. The diameter of the opening 13a is the same (or approximately the same) as the diameter of the imaginary circle VC shown in FIG. 2.

[0031] Such a ground pattern 13 is formed on at least one of the first surface 10a and the second surface 10b of the mounting board 10. Alternatively, the ground pattern 13 may be formed as an inner layer pattern of the mounting board 10. When the ground pattern 13 is formed as an inner layer pattern of the mounting board 10, it may be formed in only one layer or in multiple layers. By providing such a ground pattern 13, it is possible to improve the transmission characteristics.

[0032] <Antenna board> The antenna substrate 20 is a substrate having an antenna (not shown) formed on the first surface 20a or inside. Any material may be used for the antenna substrate 20, but it is more preferable that the material has a small dielectric tangent (small loss of high-frequency signals) and good transmission characteristics for high-frequency signals. Examples of such materials include liquid crystal polymers (LCP), polyphenylene ether (PPE) resins, low-temperature co-fired ceramics (LTCC), and fluororesins such as polytetrafluoroethylene (PTFE).

[0033] The antenna of the antenna substrate 20 may be, for example, an array antenna in which a plurality of radiating elements (not shown) are two-dimensionally arranged on the first surface 20a of the antenna substrate 20. The antenna may be any antenna, such as a linear antenna, a planar antenna, a microstrip antenna, or a patch antenna. The antenna is not particularly limited as long as it has a structure that can be formed on or inside the first surface 20a of the antenna substrate 20.

[0034] The antenna substrate 20 is mounted on the second surface 10b side of the mounting substrate 10. In this state, the second surface 20b of the antenna substrate 20 faces the second surface 10b of the mounting substrate 10. A signal metal terminal 21 (second signal metal terminal) and a ground metal terminal 22 (second ground metal terminal 22) are provided between the second surface 10b of the mounting substrate 10 and the antenna substrate 20. The signal metal terminal 21 and the ground metal terminal 22 can be made of a metal such as solder (SnAgCu solder or the like), gold, silver, or copper.

[0035] The signal metal terminal 21 electrically connects the end (other end) of the signal through hole 11 located on the second surface 10b side of the mounting substrate 10 to the antenna substrate 20. The signal metal terminal 21 is joined to the end of the signal through hole 11 and is arranged at a position overlapping the signal through hole 11 in the thickness direction of the mounting substrate 10. This makes it possible to reduce the transmission distance of the high-frequency signal from the signal through hole 11 to the antenna substrate 20 and reduce the transmission loss of the high-frequency signal, compared to a case where the signal metal terminal 21 is arranged at a position not overlapping the signal through hole 11. Note that, in FIG. 1, only one signal metal terminal 21 is shown for the sake of simplicity, but a plurality of signal metal terminals 21 may be provided on the second surface 10b of the mounting substrate 10.

[0036] The ground metal terminal 22 is a metal terminal of ground potential, and a plurality of ground metal terminals 22 are provided for the same signal metal terminal 21 (see FIG. 2). As shown in FIG. 2, the plurality of ground metal terminals 22 are provided at different positions in the circumferential direction centered on the signal metal terminal 21 in a plan view seen from the thickness direction of the mounting board 10. The plurality of ground metal terminals 22 may be arranged at equal intervals in the circumferential direction centered on the signal metal terminal 21, for example. In this embodiment, the number of ground metal terminals 22 corresponding to the same signal metal terminal 21 is four. These four ground metal terminals 22 are positioned at 90 degrees each in the circumferential direction centered on the signal metal terminal 21. The number of ground metal terminals 22 is desirably four or more, similar to the number of ground through holes 12, for example.

[0037] In this embodiment, each ground metal terminal 22 is electrically connected to both the mounting board 10 and the antenna board 20. That is, the ground metal terminal 22 electrically connects the mounting board 10 and the antenna board 20. Also, each ground metal terminal 22 is electrically connected to an end of the ground through hole 12 located on the second surface 10b side of the mounting board 10. Specifically, the ground metal terminal 22 is joined to the end of the ground through hole 12, has a center located inside the imaginary circle VC shown in FIG. 2, and is arranged so that at least a part of the ground metal terminal 22 overlaps with the ground through hole 12 in the thickness direction of the mounting board 10. The reason for this arrangement is to reduce the mounting area of ​​the components (e.g., the antenna board 20, etc.) mounted on the second surface 10b of the mounting board 10, thereby reducing the area of ​​the mounting board 10.

[0038] The signal metal terminal 21 and the ground metal terminal 22 are arranged to have an impedance-matched pseudo-coaxial structure, similar to the above-mentioned signal through-hole 11 and ground through-hole 12. The reason for this arrangement is to reduce transmission loss even at the connection portion where the mounting board 10 and the antenna board 20 are connected.

[0039] In a state in which the antenna substrate 20 is mounted on the second surface 10b side of the mounting substrate 10 (see FIG. 1), it is desirable that the signal metal terminal 21 and the ground metal terminal 22 are surrounded by a material having a dielectric constant lower than that of the mounting substrate 10. For example, it is desirable that the signal metal terminal 21 and the ground metal terminal 22 are surrounded by air (dielectric constant of about 1).

[0040] By doing so, it is possible to achieve impedance matching even if the diameters of the signal metal terminal 21 and the ground metal terminal 22 are larger than the diameters of the signal through-hole 11 and the ground through-hole 12. Furthermore, by increasing the diameters of the signal metal terminal 21 and the ground metal terminal 22, the bonding strength between the mounting substrate 10 and the antenna substrate 20 can be increased.

[0041] The above-mentioned formula (1) can be approximately applied to the pseudo-coaxial structure formed by the signal metal terminal 21 and the ground metal terminal 22. Specifically, if the connection terminal diameter of the signal metal terminal 21 (the diameter of the smaller surface of the surfaces where the signal metal terminal 21 is in contact with the mounting board 10 and the antenna board 20) is taken as the diameter d of the inner conductor and the diameter of the imaginary circle passing through the center of the ground metal terminal 22 is taken as the diameter D of the outer conductor, the characteristic impedance of the pseudo-coaxial structure can be obtained from the above formula (1). For example, if the signal metal terminal 21 and the ground metal terminal 22 are surrounded by air (dielectric constant is about 1), and the diameter of the imaginary circle passing through the center of the ground metal terminal 22 is 0.9 [mm], the characteristic impedance of the pseudo-coaxial structure formed by the signal metal terminal 21 and the ground metal terminal 22 can be set to 50 [Ω] by setting the connection terminal diameter of the signal metal terminal 21 to 0.305 [mm].

[0042] It is preferable that no other components are mounted (implemented) on the antenna board 20. This allows the area and thickness of the antenna board 20 to be minimized, and also ensures the reliability of the antenna board 20. However, if necessary, other components may be mounted on the antenna board 20.

[0043] <RFIC> The RFIC 30 is an integrated circuit that processes high-frequency signals, and is mounted on the first surface 10a side of the mounting substrate 10. The IC package applied to the RFIC 30 may be, for example, a BGA (Ball Grid Alley), a CSP (Chip Size Package), or a FOWLP (Fan Out Wafer Level Package). The RFIC 30 is electrically connected to the antenna substrate 20 via a signal metal terminal 31, a signal through hole 11 of the mounting substrate 10, and a signal metal terminal 21, which will be described later. The RFIC 30 performs, for example, a reception process of a high-frequency signal output from the antenna substrate 20, and outputs a reception signal having a lower frequency than the high-frequency signal from an output terminal (not shown). The RFIC 30 also performs, for example, a transmission process of a transmission signal input from an input terminal (not shown), and outputs a high-frequency signal having a higher frequency than the transmission signal to the antenna substrate 20.

[0044] A signal metal terminal 31 (first signal metal terminal) and a ground metal terminal 32 (first ground metal terminal) are provided between the mounting substrate 10 and the RFIC 30. The signal metal terminal 31 and the ground metal terminal 32 may be made of a material such as solder (SnAgCu solder or the like), gold, silver, copper, or the like.

[0045] The signal metal terminal 31 electrically connects an end (one end) of the signal through hole 11 located on the first surface 10a side of the mounting substrate 10 to the RFIC 30. The signal metal terminal 31 is joined to the end of the signal through hole 11 and is arranged at a position overlapping the signal through hole 11 in the thickness direction of the mounting substrate 10. This makes it possible to reduce the transmission distance of the high frequency signal from the signal through hole 11 to the RFIC 30 and reduce the transmission loss of the high frequency signal, compared to a case where the signal metal terminal 31 is arranged at a position not overlapping the signal through hole 11. Note that, in FIG. 1, only one signal metal terminal 31 is illustrated for the sake of simplicity, but a plurality of signal metal terminals 31 may be provided on the first surface 10a of the mounting substrate 10.

[0046] The ground metal terminal 32 is a metal terminal of ground potential, and a plurality of ground metal terminals 32 are provided for the same signal metal terminal 31 (see FIG. 2). The plurality of ground metal terminals 32 are provided at different positions in the circumferential direction around the signal metal terminal 31 in a plan view, similar to the plurality of ground metal terminals 22. The plurality of ground metal terminals 32 may be arranged at equal intervals in the circumferential direction around the signal metal terminal 31. In this embodiment, the number of ground metal terminals 32 corresponding to the same signal metal terminal 31 is four. These four ground metal terminals 32 are positioned at 90 degrees each in the circumferential direction around the signal metal terminal 31. The number of ground metal terminals 32 is desirably four or more, similar to the number of ground through holes 12.

[0047] In this embodiment, each ground metal terminal 32 is electrically connected to both the mounting board 10 and the RFIC 30. That is, the ground metal terminal 32 electrically connects the mounting board 10 and the RFIC 30. Also, each ground metal terminal 32 is electrically connected to an end of the ground through hole 12 located on the first surface 10a side of the mounting board 10. Specifically, the ground metal terminal 32 is joined to an end (one end) of the ground through hole 12, has a center located inside the imaginary circle VC shown in FIG. 2, and is disposed so as to overlap at least a part of the ground through hole 12 in the thickness direction of the mounting board 10. The reason for such an arrangement is to reduce the mounting area of ​​the components (e.g., RFIC 30, etc.) mounted on the first surface 10a of the mounting board 10, thereby reducing the area of ​​the mounting board 10.

[0048] The signal metal terminal 31 and the ground metal terminal 32 are arranged to have an impedance-matched pseudo-coaxial structure, similar to the above-mentioned signal through-hole 11 and ground through-hole 12. The reason for this arrangement is to reduce transmission loss even at the connection portion where the mounting board 10 and the RFIC 30 are connected.

[0049] In a state in which the RFIC 30 is mounted on the first surface 10a side of the mounting substrate 10 (see FIG. 1), it is desirable that the signal metal terminal 31 and the ground metal terminal 32 are surrounded by a material having a dielectric constant lower than that of the mounting substrate 10. For example, it is desirable that the signal metal terminal 31 and the ground metal terminal 32 are surrounded by air (dielectric constant of about 1).

[0050] This makes it possible to achieve impedance matching even if the diameters of the signal metal terminal 31 and the ground metal terminal 32 are larger than the diameters of the signal through-hole 11 and the ground through-hole 12. Furthermore, by increasing the diameters of the signal metal terminal 31 and the ground metal terminal 32, the bonding strength between the mounting substrate 10 and the RFIC 30 can be increased.

[0051] The above-mentioned formula (1) can be approximately applied to the pseudo-coaxial structure of the signal metal terminal 31 and the ground metal terminal 32, as in the pseudo-coaxial structure of the signal metal terminal 21 and the ground metal terminal 22. Specifically, if the connection terminal diameter of the signal metal terminal 31 (the diameter of the smaller surface of the surfaces where the signal metal terminal 31 is in contact with the mounting board 10 and the RFIC 30) is the diameter d of the inner conductor, and the diameter of the imaginary circle passing through the center of the ground metal terminal 32 is the diameter D of the outer conductor, the characteristic impedance of the pseudo-coaxial structure can be obtained from the above formula (1). For example, if the signal metal terminal 31 and the ground metal terminal 32 are surrounded by air (dielectric constant is about 1), and the diameter of the imaginary circle passing through the center of the ground metal terminal 32 is 0.9 [mm], the characteristic impedance of the pseudo-coaxial structure of the signal metal terminal 31 and the ground metal terminal 32 can be set to 50 [Ω] by setting the connection terminal diameter of the signal metal terminal 31 to 0.305 [mm].

[0052] 1 and 2, in the wireless communication module 1 of this embodiment, the signal metal terminal 21 and the signal metal terminal 31 overlap in the thickness direction of the mounting substrate 10. Furthermore, the four ground metal terminals 22 and the four ground metal terminals 32 overlap in the thickness direction of the mounting substrate 10. The signal metal terminals 21 and the signal metal terminals 31 may completely overlap or only partially overlap. Similarly, the ground metal terminals 22 and the ground metal terminals 32 may completely overlap or only partially overlap.

[0053] As described above, in the wireless communication module 1 of the present embodiment, the signal metal terminal 21 is surrounded by a plurality of ground metal terminals 22 between the mounting board 10 and the antenna board 20. In addition, the signal metal terminal 31 is surrounded by a plurality of ground metal terminals 32 between the mounting board 10 and the RFIC 30. This achieves impedance matching at the connection portion where the mounting board 10 and the antenna board 20 are connected and at the connection portion where the mounting board 10 and the RFIC 30 are connected, thereby making it possible to reduce the reflection of high-frequency signals at these connection portions. As a result, it is possible to reduce the transmission loss of high-frequency signals at these connection portions.

[0054] Furthermore, in the wireless communication module 1 of the present embodiment, the signal metal terminal 21 and the signal metal terminal 31 are disposed at positions overlapping the signal through-hole 11 in the thickness direction of the mounting substrate 10. This makes it possible to shorten the transmission distance of the high-frequency signal from the signal through-hole 11 to the antenna substrate 20 and the transmission distance from the signal through-hole 11 to the RFIC 30, thereby reducing the transmission loss of the high-frequency signal.

[0055] Furthermore, in the wireless communication module 1 of this embodiment, the ground metal terminal 22 and the ground metal terminal 32 are provided so that their centers are located inside an imaginary circle VC that is centered on the signal through-hole 11 and passes through the center of the ground through-hole 12. This makes it possible to reduce the mounting area of ​​the components (e.g., the antenna substrate 20, the RFIC 30, etc.) mounted on the mounting board 10, and therefore the area of ​​the mounting board 10.

[0056] Moreover, in the wireless communication module 1 of the present embodiment, the signal through hole 11 of the mounting board 10 is surrounded by a plurality of ground through holes 12. As a result, an impedance-matched pseudo-coaxial structure is formed on the mounting board 10, so that the transmission loss of the high-frequency signal transmitted through the signal through hole 11 can be reduced.

[0057] First Modified Example Fig. 4 is a side cross-sectional view showing a main configuration of a wireless communication module according to a first modified example. Fig. 5 is a cross-sectional view taken along line BB in Fig. 4. In Figs. 4 and 5, the same components as those shown in Figs. 1 and 2 are denoted by the same reference numerals. As shown in Figs. 4 and 5, a wireless communication module 2 according to this modified example includes a mounting substrate 10, an antenna substrate 20, and an RFIC 30, similar to the wireless communication module 1 shown in Figs. 1 and 2. However, the wireless communication module 2 according to this modified example differs from the wireless communication module 1 shown in Figs. 1 and 2 in the arrangement and connection method of the ground metal terminals 22 and 32.

[0058] 1 and 2, the ground metal terminals 22, 32 are disposed so that their centers are located inside the imaginary circle VC shown in Fig. 2 and so as to at least partially overlap with the ground through hole 12 in the thickness direction of the mounting substrate 10. In contrast, in the wireless communication module 2 according to this modification, the ground metal terminals 22, 32 are disposed so that their entirety is located inside the imaginary circle VC and so as not to overlap with the ground through hole 12 in the thickness direction of the mounting substrate 10.

[0059] By arranging the ground metal terminals 22, 32 in this manner, the diameter of an imaginary circle passing through the center of the ground metal terminals 22, 32 (the diameter D of the external conductor in the above-mentioned formula (1)) becomes smaller. Then, in order to maintain the ratio (D / d) of the diameters of the external conductor and the internal conductor, it is necessary to reduce the diameter d of the internal conductor (the connection terminal diameter of the signal metal terminals 21, 31). This means that it is possible to make the wireless communication module smaller than that of the wireless communication module 1 shown in FIG. 1. Furthermore, by reducing the connection terminal diameter of the signal metal terminals 21, 31, the external shape of the signal metal terminals 21, 31 inevitably becomes smaller, and therefore the transmission distance of the high-frequency signal in the thickness direction of the mounting substrate 10 can be shortened. This makes it possible to reduce the transmission loss of the high-frequency signal.

[0060] The signal metal terminal 21 and the ground metal terminal 22, and the signal metal terminal 31 and the ground metal terminal 32 are surrounded by air (ε r= 1). In this case, in order to make the characteristic impedance of the pseudo-coaxial structure formed by the signal metal terminal 21 and the ground metal terminal 22 and the pseudo-coaxial structure formed by the signal metal terminal 31 and the ground metal terminal 32 50 [Ω], the diameter ratio (D / d) of the outer conductor to the inner conductor in the above-mentioned formula (1) should be about 2.95.

[0061] Here, the ground metal terminals 22 and 32 may be connected, for example, only to the mounting substrate 10, and may not be connected to the antenna substrate 20 or the RFIC 30. Alternatively, the ground metal terminal 22 may be connected, for example, only to the antenna substrate 20, and may not be connected to the mounting substrate 10. Similarly, the ground metal terminal 32 may be connected, for example, only to the RFIC 30, and may not be connected to the mounting substrate 10. Note that the ground metal terminals 22 and 32 may be provided such that some of them connect the mounting substrate 10 and the antenna substrate 20 or the RFIC 30, and the remaining parts do not connect the mounting substrate 10 and the antenna substrate 20 or the RFIC 30.

[0062] In consideration of the continuity of the electric field distribution, it is desirable that the ground metal terminals 22, 32 are arranged on a straight line connecting the center of the signal through hole 11 and the center of the ground through hole 12. In this case, the ground metal terminals 22, 32 may be arranged so that a part of them overlaps with the ground through hole 12 in the thickness direction of the mounting board 10, or may not overlap.

[0063] <Second Modification> Fig. 6 is a side cross-sectional view showing the main configuration of a wireless communication module according to a second modified example. In Fig. 6, the same components as those shown in Figs. 1 and 2 are denoted by the same reference numerals. As shown in Fig. 6, the wireless communication module 3 according to this modified example is different from the wireless communication module 1 shown in Figs. 1 and 2 in that the antenna substrate 20 is omitted. Also, the signal through-hole 11 and the ground through-hole 12 of the mounting substrate 10 extend from the first surface 10a to the second surface 10b, but do not penetrate to the second surface 10b. In other words, the signal through-hole 11 and the ground through-hole 12 are blind vias.

[0064] In such a wireless communication module 3, for example, an antenna element (not shown) is formed inside the mounting board 10, and therefore the antenna substrate 20 is omitted. A signal pattern 14 and a ground pattern 15 are formed on the mounting board 10 as inner layer substrates. The signal pattern 14 is connected to, for example, a signal terminal of the antenna element formed inside the mounting board 10, and the ground pattern 15 is connected to, for example, a ground terminal of the antenna element formed inside the mounting board 10.

[0065] 6, the signal through hole 11 is electrically connected to a signal pattern 14 formed as an inner layer of the mounting board 10, and the ground through hole 12 is electrically connected to a ground pattern 15 formed as an inner layer of the mounting board 10. As a result, the antenna element formed on the mounting board 10 and the RFIC 30 mounted on the first surface 10a of the mounting board 10 are electrically connected via the signal through hole 11 and the ground through hole 12.

[0066] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments and can be freely modified within the scope of the present invention. For example, the wireless communication modules 1 and 2 in the above-mentioned embodiments have the antenna board 20 and the RFIC 30 mounted on the mounting board 10. However, the mounting board 10 may have other components (not shown) mounted thereon in addition to the antenna board 20 and the RFIC 30.

[0067] In the above-described embodiment, an example has been described in which the antenna substrate 20 is mounted on the second surface 10b of the mounting substrate 10, and the RFIC 30 is mounted on the first surface 10a of the mounting substrate 10. However, the opposite may also be true, in which the RFIC 30 is mounted on the second surface 10b of the mounting substrate 10, and the antenna substrate 20 is mounted on the first surface 10a of the mounting substrate 10. [Explanation of symbols]

[0068] Reference Signs List 1 to 3: wireless communication module, 10: mounting board, 10a: first surface, 10b: second surface, 11: signal through-hole, 12: ground through-hole, 20: antenna board, 21: signal metal terminal, 22: ground metal terminal, 30: RFIC, 31: signal metal terminal, 32: ground metal terminal

Claims

1. a mounting substrate on which a signal via extending from a first surface to a second surface opposite to the first surface through which a high frequency signal is transmitted, and a plurality of ground vias extending from the first surface to the second surface and set to a ground potential, the ground vias being provided at different positions in a circumferential direction around the signal via; A first mounting component mounted on the first surface side; a first signal metal terminal that connects one end of the signal via located on the first surface side to the first mounting component; a plurality of first ground metal terminals provided between the first surface and the first mounting component, the centers of which are located inside an imaginary circle that is centered on the signal via and passes through the center of the ground via; Equipped with the first ground metal terminal is connected to both one end of the ground via located on the first surface side and the first mounting component facing the first surface; Wireless communication module.

2. 2. The wireless communication module according to claim 1, wherein the first signal metal terminal and the first ground metal terminal are arranged to form an impedance-matched pseudo-coaxial structure.

3. 3. The wireless communication module according to claim 1, wherein the first signal metal terminal and the first ground metal terminal are surrounded by a material having a dielectric constant lower than a dielectric constant of the mounting substrate.

4. 4. The wireless communication module according to claim 1, wherein the signal via and the ground via are arranged to form an impedance-matched pseudo-coaxial structure.

5. the signal via and the ground via extend from the first surface to the second surface; A second mounting component mounted on the second surface side; a second signal metal terminal that connects the other end of the signal via located on the second surface side to the second mounted component; a plurality of second ground metal terminals provided between the second surface and the second mounting component, the second ground metal terminals being centered within the imaginary circle; The wireless communication module according to claim 1 , further comprising:

6. the first mounting component is either an antenna substrate or a high-frequency integrated circuit, the second mounting component is the other of the antenna board and the high-frequency integrated circuit; The wireless communication module according to claim 5.

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