Substrate and antenna module

Abstract

The present invention relates to a substrate and an antenna module. The substrate having through-holes formed from a first surface to a second surface opposite to the first surface includes: two first through-holes that are arranged in parallel with a predetermined interval and transmit high-frequency signals; and at least three second through-holes of a reference potential, which are arranged in parallel with the two first through-holes with an interval narrower than the predetermined interval. Among the three second through-holes, one second through-hole is disposed in a region between the two first through-holes, and the other two second through-holes are disposed in a region other than the region between the first through-holes in such a manner that one of the other two second through-holes is arranged in parallel with one of the two first through-holes, and the other of the other two second through-holes is arranged in parallel with the other of the two first through-holes.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority based on Japanese Patent Application No. 2020 - 005342 filed on January 16, 2020, and the content thereof is incorporated herein by reference. Technical field

[0003] The present invention relates to a substrate and an antenna module. Background art

[0004] In a substrate for transmitting high - frequency signals such as millimeter - waves, through - holes having a coaxial structure are sometimes formed. This is to minimize the transmission loss of high - frequency signals transmitted through the through - holes by performing impedance matching of the through - holes. In Patent Document 1 below, through - holes formed as a pseudo - coaxial structure are disclosed, in which through - holes (through - hole conductors) for transmitting high - frequency signals are surrounded by a large number of through - holes (through - hole conductors) at ground potential.

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2003 - 100941

[0006] In recent years, the pitch of high - frequency integrated circuits (RFICs: Radio Frequency Integrated Circuits) mounted on a substrate has been narrow, and it is considered that it will become narrower in the future. Along with this, it is required that the pitch of through - holes formed in the substrate also becomes narrower. The through - holes disclosed in the above - mentioned Patent Document 1 have a structure in which through - holes at ground potential surround through - holes for transmitting high - frequency signals in a ring shape, and thus are not suitable for narrowing the pitch. Summary of the invention

[0007] The present invention has been made in view of the above circumstances, and provides a substrate capable of arranging impedance - matched through - holes with a higher density than in the past, and an antenna module including the substrate.

[0008] A first aspect of the present invention is a substrate (30) having through - holes extending from a first surface (30a) to a second surface (30b) opposite to the first surface, the substrate (30) comprising: two first through - holes (31a) arranged in parallel with a predetermined interval therebetween and transmitting high - frequency signals; and at least three second through - holes (31b) at a reference potential, arranged in parallel with respect to the two first through - holes with an interval narrower than the predetermined interval. Among the three second through - holes, one second through - hole is arranged in a region (R1) between the two first through - holes, and the other two second through - holes are arranged in regions other than the region between the first through - holes in such a manner that one of the other two second through - holes is arranged in parallel with one of the two first through - holes, and the other of the other two second through - holes is arranged in parallel with the other of the two first through - holes.

[0009] In the substrate of the first aspect of the present invention described above, at least three second through-holes arranged in parallel with two first through-holes for transmitting high-frequency signals, one of which is disposed in a region between the two first through-holes. Thereby, this one second through-hole can be shared by the two first through-holes, and the interval between the two first through-holes can be narrowed. Therefore, through-holes after impedance matching can be arranged at a higher density than in the past.

[0010] In the second aspect of the present invention, preferably, based on the substrate of the first aspect described above, the second through-hole disposed in the region between the two first through-holes is disposed at a position that is approximately equidistant from each of the first through-holes.

[0011] In the third aspect of the present invention, preferably, based on the substrate of the first or second aspect described above, the second through-hole disposed in the region between the two first through-holes is disposed on a straight line (L1) connecting the centers of the first through-holes.

[0012] In the fourth aspect of the present invention, preferably, based on the substrate of any one of the first to third aspects described above, the first through-hole and the second through-hole are arranged to have a pseudo coaxial structure after impedance matching.

[0013] In the fifth aspect of the present invention, preferably, based on the substrate of any one of the first to fourth aspects described above, it further includes a ground pattern (33) for impedance matching that is electrically connected to the second through-hole.

[0014] In the sixth aspect of the present invention, preferably, based on the substrate of the fifth aspect described above, the ground pattern is provided with at least one layer inside the substrate.

[0015] In the seventh aspect of the present invention, preferably, based on the substrate of the first to sixth aspects described above, electrode pads (LC1) are formed at both ends of the first through-hole.

[0016] In the eighth aspect of the present invention, preferably, the substrate of any one of the first to seventh aspects described above includes a plurality of third through-holes (32) for transmitting non-high-frequency signals different from the high-frequency signals, and the interval between the first through-holes is different from the interval between the third through-holes.

[0017] A ninth aspect of the present invention is an antenna module (1), the antenna module (1) including an antenna substrate (10) formed with an antenna (11), a high-frequency integrated circuit (20) for processing high-frequency signals, and the substrate (30) according to any one of the first to eighth aspects. The antenna substrate and the high-frequency integrated circuit are respectively mounted on the first surface and the second surface of the substrate in a manner that at least a part thereof overlaps in a top view, and are electrically connected via the first through hole.

[0018] In a tenth aspect of the present invention, it is preferable that, based on the antenna module of the ninth aspect, the substrate is formed of a material having a dielectric loss factor larger than that of the material of the antenna substrate.

[0019] According to one aspect of the present invention, through holes after impedance matching can be arranged with a higher density than in the past. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 FIG. is a cross-sectional view showing a main part structure of an antenna module according to an embodiment of the present invention.

[0021] Figure 2 is along Figure 1 a cross-sectional view taken along line A-A of

[0022] Figure 3 FIG. is a top view for explaining a region between high-frequency signal through holes in an embodiment of the present invention.

[0023] Figure 4 FIG. is a view showing a surface of a component mounting substrate in an embodiment of the present invention.

[0024] Figure 5 FIG. is a cross-sectional view showing a component mounting substrate according to a first modification.

[0025] Figure 6 FIG. is a cross-sectional view showing a component mounting substrate according to a second modification.

[0026] Figure 7 FIG. is a cross-sectional view showing an antenna module according to a third modification. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, a substrate and an antenna module according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, in order to facilitate understanding of the structure, for convenience, in the following description, there are cases where parts of each structural element are enlarged in the drawings, and the dimensional ratios and the like of each structural element are not necessarily the same as the actual ones. Further, the present invention is not limited to the following embodiments.

[0028] <Main Part Structure of Antenna Module>

[0029] Figure 1 is a cross-sectional view showing the main part structure of an antenna module according to an embodiment of the present invention. As Figure 1 shown, the antenna module 1 includes an antenna substrate 10 (high-frequency substrate), an RFIC 20 (high-frequency integrated circuit), and a component mounting substrate 30, and performs transmission and reception of high-frequency signals such as millimeter waves in the frequency range of about 50 to 70 [GHz], for example. In addition, the antenna module 1 can perform only transmission of high-frequency signals or only reception.

[0030] 〈Antenna Substrate〉

[0031] The antenna substrate 10 is a substrate on which an antenna 11 is formed on the surface (first surface 10a) or inside, and is mounted on the first surface 30a side of the component mounting substrate 30. The antenna substrate 10 is formed of a material having a small dielectric loss factor (small loss of high-frequency signals) and excellent transmission characteristics of high-frequency signals. As such a material, for example, fluororesin, liquid crystal polymer (LCP), polyphenylene ether (PPE) resin, low-temperature fired ceramics, etc. can be cited. The antenna substrate 10 has the minimum necessary area (area in a top view perspective) in order to reduce costs.

[0032] The antenna 11 is, for example, an array antenna in which a plurality of radiating elements (not shown) are arranged two-dimensionally on the first surface 10a of the antenna substrate 10. In addition, as the antenna 11, in addition to the array antenna, a linear antenna, a planar antenna, a microstrip antenna, a patch antenna, or other antennas can also be used. Furthermore, the antenna 11 is not particularly limited as long as it is a structure that can be formed on the surface (first surface 10a) or inside of the antenna substrate 10.

[0033] A plurality of metal terminals 12 are provided on the second surface 10b of the antenna substrate 10. As the material of the metal terminal 12, for example, a metal such as solder can be used. The metal terminal 12 includes a plurality of connection metal terminals 12a, a plurality of connection metal terminals 12b, and a plurality of fixing metal terminals 12c.

[0034] The connection metal terminal 12a electrically connects the antenna substrate 10 to a pseudo coaxial structure through-hole 31 (details will be described later) formed in the component mounting substrate 30. The connection metal terminal 12b electrically connects the antenna substrate 10 to a non-high-frequency signal through-hole 32 (details will be described later) formed in the component mounting substrate 30. The fixing metal terminal 12c does not electrically connect to the circuit formed in the component mounting substrate 30, but fixes the antenna substrate 10 to the component mounting substrate 30.

[0035] In a top-down view, the connection metal terminals 12a and the pseudo-coaxial structure through-holes 31 of the component mounting substrate 30 are arranged identically. That is, when the antenna substrate 10 is aligned with the component mounting substrate 30, each of the connection metal terminals 12a of the antenna substrate 10 is arranged to overlap one-to-one with each of the pseudo-coaxial structure through-holes 31 of the component mounting substrate 30. For example, the connection metal terminals 12a are arranged at intervals of about 0.1 to 0.5 [mm]. Thereby, the transmission distance of high-frequency signals can be made the shortest, and the transmission loss of high-frequency signals can be minimized. The connection metal terminals 12b may also be arranged identically to the non-high-frequency signal through-holes 32 of the component mounting substrate 30 in a top-down view.

[0036] In a state where the antenna substrate 10 is mounted on the component mounting substrate 30, it is preferable that the connection metal terminals 12a have a structure not covered by resin or the like, and it is preferable that the connection metal terminals 12b and the fixing metal terminals 12c have a structure covered by resin. Since the connection metal terminals 12a are not covered by resin or the like, the transmission loss of high-frequency signals can be reduced. Since the connection metal terminals 12b and the fixing metal terminals 12c are covered by resin, the connection portion between the antenna substrate 10 and the component mounting substrate 30 can be strengthened.

[0037] It is preferable that no other components are mounted on the antenna substrate 10. This is to minimize the area and thickness of the antenna substrate 10 as much as possible and ensure reliability, etc. Among them, if necessary, other components may also be mounted on the antenna substrate 10.

[0038] 〈RFIC〉

[0039] The RFIC 20 is an integrated circuit that processes high-frequency signals and is mounted on the second surface 30b side of the component mounting substrate 30. The RFIC 20 is electrically connected to the antenna substrate 10 via the pseudo-coaxial structure through-holes 31, the non-high-frequency signal through-holes 32, and the metal terminals 12 (connection metal terminals 12a, 12b) of the component mounting substrate 30. The RFIC 20, for example, performs reception processing of high-frequency signals output from the antenna substrate 10 and outputs a reception signal having a frequency lower than that of the high-frequency signal from an output terminal (not shown). The RFIC 20, for example, performs transmission processing of a transmission signal input from an input terminal (not shown) and outputs a high-frequency signal having a frequency higher than that of the transmission signal to the antenna substrate 10.

[0040] A plurality of metal terminals 21 are provided on the first surface 20a of the RFIC 20. As the material of the metal terminals 21, for example, metals such as solder (SnAgCu solder, etc.), gold, silver, and copper can be used. The metal terminals 21 include a plurality of metal terminals 21a and a plurality of metal terminals 21b.

[0041] The metal terminal 21a electrically connects the RFIC 20 to the pseudo coaxial structure through-hole 31 of the component mounting substrate 30. The metal terminal 21b electrically connects the RFIC 20 to the non-high-frequency signal through-hole 32 of the component mounting substrate 30. For example, the joining of the metal terminal 21a to the pseudo coaxial structure through-hole 31 and the joining of the metal terminal 21b to the non-high-frequency signal through-hole 32 are performed by solder bonding, but ultrasonic bonding, pressure welding based on pressurization, or other joining methods can also be used.

[0042] In a plan view, the metal terminals 21a are arranged in the same manner as the pseudo coaxial structure through-holes 31 of the component mounting substrate 30. That is, when the RFIC 20 and the component mounting substrate 30 are aligned, each of the metal terminals 21a of the RFIC 20 is arranged to overlap one-to-one with each of the pseudo coaxial structure through-holes 31 of the component mounting substrate 30. For example, the metal terminals 21a are the same as the connection metal terminals 12a of the antenna substrate 10 and are arranged at a pitch of about 0.1 to 0.5 [mm]. Thereby, the transmission distance of the high-frequency signal can be made the shortest, and the transmission loss of the high-frequency signal can be made the smallest. The metal terminals 21b can also be arranged in the same manner as the non-high-frequency signal through-holes 32 of the component mounting substrate 30 in a plan view.

[0043] Preferably, the metal terminal 21a has a structure that is not covered by resin or the like in a state where the RFIC 20 is mounted on the component mounting substrate 30. For example, preferably, the structure is such that the bottom surface filler does not seal between the first surface 20a of the RFIC 20 and the second surface 30b of the component mounting substrate 30. Since the metal terminal 21a is not covered by resin or the like, the transmission loss of the high-frequency signal can be reduced.

[0044] 〈Component mounting substrate〉

[0045] The component mounting substrate 30 is a substrate on which components such as the antenna substrate 10 and the RFIC 20 are mounted. The component mounting substrate 30 is formed of a material having a dielectric loss factor greater than that of the antenna substrate 10. As such a material, for example, inexpensive materials (e.g., epoxy resin, polyimide, etc.) that are commonly used as materials for rigid substrates or flexible substrates can be cited.

[0046] Preferably, the thickness of the component mounting substrate 30 is, for example, about 1.6 [mm] or less. A smaller thickness of the component mounting substrate 30 is advantageous for forming minute through-holes. For example, when forming minute through-holes having a diameter of about 0.1 [mm], it is preferable to use a component mounting substrate 30 having a thickness of about 0.8 [mm] or less.

[0047] On the component mounting substrate 30, a pseudo coaxial structure through hole 31 and a non-high-frequency signal through hole 32 (third through hole) are formed from the first surface 30a to the second surface 30b of the component mounting substrate 30. In addition, in Figure 1 For the sake of simplifying the illustration, each figure shows one pseudo coaxial structure through hole 31 and one non-high-frequency signal through hole 32, but multiple of these can also be provided.

[0048] The pseudo coaxial structure through hole 31 is a through hole provided for transmitting high-frequency signals. The pseudo coaxial structure through hole 31 is composed of two high-frequency signal through holes 31a (first through holes) and at least three ground through holes 31b (second through holes) arranged in parallel with respect to the two high-frequency signal through holes 31a (see Figure 2 ). One of the three ground through holes 31b is arranged in the region between the two high-frequency signal through holes 31a (described later, see Figure 3 ). For the other two ground through holes 31b, they are arranged in regions other than the region between the high-frequency signal through holes 31a in such a manner that: one ground through hole 31b is arranged in parallel with one high-frequency signal through hole 31a, and the other ground through hole 31b is arranged in parallel with the other high-frequency signal through hole 31a.

[0049] The high-frequency signal through hole 31a is a through hole for transmitting high-frequency signals. The ground through hole 31b is a through hole for ground potential (reference potential). The high-frequency signal through hole 31a and the ground through hole 31b are arranged such that the pseudo coaxial structure through hole 31 has a pseudo coaxial structure with impedance matching.

[0050] Here, if there is only one ground through hole 31b arranged in parallel with one high-frequency signal through hole 31a, the effect of enclosing the electric field of the high-frequency signal is insufficient, and good characteristics cannot be obtained. Therefore, in the present embodiment, two ground through holes 31b (shared in the pseudo coaxial structure through holes 31A and 31B) are arranged in parallel with one high-frequency signal through hole 31a to reduce the transmission loss of the high-frequency signal.

[0051] In addition, the number of ground through holes 31b arranged in parallel with the high-frequency signal through hole 31a can also be three or more. Among them, if the number of ground through holes 31b increases, it becomes the same as the through hole of the pseudo coaxial structure described in the prior art documents, and it is not suitable for narrowing the pitch. In addition, the cost increases, and it is easy to cause defects such as breakage due to the narrowing of the interval between the ground through holes 31b. Therefore, as long as a pseudo coaxial structure with impedance matching is obtained, it is preferable that the number of ground through holes 31b is as small as possible (two or more).

[0052] Here, the pseudo-coaxial structure after impedance matching refers to a structure in which, when considering a coaxial structure with the high-frequency signal via-hole 31a as the center conductor, the ground via-hole 31b is arranged on or near an imaginary circle where the ground conductor surrounding the center conductor should originally be arranged. For example, if the impedance error is in the range of about ±10 [Ω], the ground via-hole 31b is allowed to deviate from the position on the above-mentioned imaginary circle.

[0053] The non-high-frequency signal via-hole 32 is a via-hole provided for transmitting low-frequency signals, power supply, ground connection, etc. whose frequency is lower than that of the high-frequency signal. The transmission loss of low-frequency signals and the like caused by impedance mismatch is very small compared to the transmission loss of high-frequency signals. Therefore, the non-high-frequency signal via-hole 32 is not a pseudo-coaxial structure like the pseudo-coaxial structure via-hole 31.

[0054] Here, the diameter of the non-high-frequency signal via-hole 32 is the same (or of the same degree) as the diameters of the high-frequency signal via-hole 31a and the ground via-hole 31b. Preferably, the diameters of the high-frequency signal via-hole 31a, the ground via-hole 31b, and the non-high-frequency signal via-hole 32 are, for example, 0.15 [mm] or less.

[0055] Preferably, the high-frequency signal via-hole 31a, the ground via-hole 31b, and the non-high-frequency signal via-hole 32 are formed by any one of a conductor pin, a conductor wire, a metal plating, a conductive paste, etc., but are not limited to these. The conductors used for the high-frequency signal via-hole 31a, the ground via-hole 31b, and the non-high-frequency signal via-hole 32 can include metals such as copper, silver, gold, alloys, and carbon. The shapes of the high-frequency signal via-hole 31a, the ground via-hole 31b, and the non-high-frequency signal via-hole 32 are not particularly limited, but can include pin-shaped, linear, layer-shaped, particle-shaped, flaky, fibrous, nanotube-shaped, etc.

[0056] In addition, a ground pattern 33 is formed on the component mounting substrate 30. The ground pattern 33 is an inner layer pattern of the component mounting substrate 30 and is electrically connected to the ground via-hole 31b. By providing the ground pattern 33, the ground via-hole 31b of the pseudo-coaxial structure via-hole 31 can be strengthened to achieve good impedance matching.

[0057] Figure 2 is a cross-sectional view along the Figure 1 A-A line. In addition, Figure 1 For example, it is a cross-sectional view along the Figure 2 B-B line in Figure 2In the example shown, among the through-holes formed in the component mounting substrate 30, three pseudo coaxial structure through-holes 31 (31A, 31B, 31C) and one non-high-frequency signal through-hole 32 are illustrated. The pseudo coaxial structure through-holes 31A and 31B are arranged close to each other to narrow the pitch. In contrast, the pseudo coaxial structure through-hole 31C is arranged at a position separated from the pseudo coaxial structure through-holes 31A and 31B by a certain degree.

[0058] As Figure 2 shown, in the ground pattern 33, there are formed openings AP that are hollowed out in a substantially circular shape around the high-frequency signal through-holes 31a respectively provided in the pseudo coaxial structure through-holes 31A, 31B, and 31C. The ground through-holes 31b respectively provided in the pseudo coaxial structure through-holes 31A, 31B, and 31C are electrically connected to the ground pattern 33. In addition, the non-high-frequency signal through-hole 32 is insulated from the ground pattern 33.

[0059] As described above, the high-frequency signal through-holes 31a and the ground through-holes 31b respectively provided in the pseudo coaxial structure through-holes 31A, 31B, and 31C are arranged with an appropriate interval so that the pseudo coaxial structure through-holes 31A, 31B, and 31C are respectively impedance-matched. For example, when the relative dielectric constant of the component mounting substrate 30 is about "4", the diameter of the high-frequency signal through-hole 31a is 0.15 [mm], and the characteristic impedance is 50 [Ω], the interval between the high-frequency signal through-hole 31a and the ground through-hole 31b is set to about 0.375 [mm].

[0060] In addition, by providing the ground pattern 33, as described above, the ground through-hole 31b can be strengthened to achieve good impedance matching. Therefore, the size of the opening AP formed in the ground pattern 33 can also be designed by the same method as the interval between the high-frequency signal through-hole 31a and the ground through-hole 31b. For example, the interval between the high-frequency signal through-hole 31a and the inner periphery of the opening AP is set to about 0.375 [mm] (the inner diameter of the opening AP is about 0.75 [mm]).

[0061] Here, when forming through-holes (high-frequency signal through-hole 31a, ground through-hole 31b), if the through-hole to be formed is close to other through-holes, there may be a situation where the substrate is damaged such as cracking. Therefore, the interval between the through-holes needs to be more than a certain distance (for example, 0.2 [mm] or more).

[0062] As Figure 2As shown, the pseudo coaxial structure through holes 31A and 31B are arranged close to each other to narrow the pitch, and there is a case where the ground through holes 31b of the pseudo coaxial structure through holes 31A and 31B are close to each other (for example, less than 0.2 [mm]). In the present embodiment, by making the ground through hole 31b arranged in the region between the two high-frequency signal through holes 31a common to both the pseudo coaxial structure through holes 31A and 31B, the above-mentioned close situation is avoided.

[0063] In Figure 2 In the example shown, when the pseudo coaxial structure through holes 31A and 31B arranged close to each other are observed as a whole, the pseudo coaxial structure through holes 31A and 31B include two high-frequency signal through holes 31a and three ground through holes 31b arranged in parallel with these high-frequency signal through holes 31a. The three ground through holes 31b are arranged on the straight line L1 in such a way that two adjacent ones sandwich one high-frequency signal through hole 31a. In addition, the straight line L1 is a straight line connecting the centers of the high-frequency signal through holes 31a of the pseudo coaxial structure through holes 31A and 31B.

[0064] The ground through hole 31b arranged in the region between the two high-frequency signal through holes 31a is arranged at a position that is approximately the same distance from each of the high-frequency signal through holes 31a. Here, the "approximately the same distance" refers to a distance considering the manufacturing error during the manufacture of the component mounting substrate 30. That is, even if the distances are not exactly the same, if the difference in distance is of the order of the manufacturing error, it can be said that the ground through hole 31b arranged in the region between the high-frequency signal through holes 31a is arranged at the same distance from each of the high-frequency signal through holes 31a.

[0065] In this way, the ground through hole 31b arranged in the region between the high-frequency signal through holes 31a is arranged on the straight line L1 and at a position that is approximately the same distance from each of the high-frequency signal through holes 31a. By being configured in this way, the influence on the characteristics generated between adjacent high-frequency signal through holes 31a can be minimized.

[0066] Figure 3 It is a top view showing the region between the high-frequency signal through holes in an embodiment of the present invention. As Figure 3As shown, the region R1 between the high-frequency signal through-holes 31a of the pseudo coaxial structure through-hole 31A and the high-frequency signal through-holes 31a of the pseudo coaxial structure through-hole 31B is the region represented by the line segment in the figure. The region R1 is the region divided by the parallel lines L11 and L12 that are tangent to two circles CR and orthogonal to the straight line L1. The two circles CR are centered on the high-frequency signal through-holes 31a of the pseudo coaxial structure through-holes 31A and 31B, and the centers of the ground through-holes 31b arranged in parallel with each high-frequency signal through-hole 31a are taken as a part of the circumference.

[0067] That is, in the present embodiment, the pseudo coaxial structure through-holes 31A and 31B are designed under the following conditions. One of the three ground through-holes 31b of the pseudo coaxial structure through-holes 31A and 31B is arranged in the region R1 between the high-frequency signal through-holes 31a. The other two ground through-holes 31b are arranged in the region outside the region R1 in such a way that: one ground through-hole 31b is arranged in parallel with one high-frequency signal through-hole 31a, and the other ground through-hole 31b is arranged in parallel with the other first through-hole 31a.

[0068] As long as the above conditions are satisfied and impedance matching is performed, the arrangement of the ground through-holes 31b can be changed. For example, in Figure 2 In the example shown, all three ground through-holes 31b are arranged on the straight line L1. However, for example, if the ground through-hole 31b arranged in the region R1 between the two high-frequency signal through-holes 31a is arranged in the region R1, it may not be arranged on the straight line L1. In addition, the other ground through-holes 31b may not be arranged on the straight line L1 either.

[0069] Figure 4 It is a diagram showing the surface of the component mounting substrate in one embodiment of the present invention. Figure 4 (a) is a top view showing the pattern formed on the second surface 30b side of the component mounting substrate 30, Figure 4 (b) is a top view showing the state where the solder resist is formed on the pattern. In addition, in Figure 4 The structure of the second surface 30b side of the component mounting substrate 30 is illustrated, but the structure of the first surface 30a side of the component mounting substrate 30 is the same.

[0070] In addition, in Figure 4 For convenience, the pseudo coaxial structure through-holes 31A and 31B marked with the same reference numerals as the pseudo coaxial structure through-holes 31A and 31B shown in Figure 2 are illustrated. However, it should be noted that Figure 4 The pseudo coaxial structure through-holes 31A and 31B shown in Figure 2The pseudo coaxial structure through holes 31A and 31B shown are of different structures (formed at different positions on the component mounting substrate 30).

[0071] In Figure 4 In the example shown in (a) of, two pseudo coaxial structure through holes 31 (31A, 31B) and two non-high-frequency signal through holes 32 (32A, 32B) are illustrated. The ground through holes 31b of the pseudo coaxial structure through holes 31A and 31B are connected to the ground pattern 33 formed on the second surface 30b of the component mounting substrate 30. In contrast, the non-high-frequency signal through holes 32A and 32B are insulated from the ground pattern 33.

[0072] Pad conductors LC1 (electrode pads) are formed around the high-frequency signal through holes 31a of the pseudo coaxial structure through holes 31A and 31B, and pad conductors LC2 are formed around the non-high-frequency signal through holes 32A and 32B. That is, the high-frequency signal through holes 31a of the pseudo coaxial structure through holes 31A and 31B and the non-high-frequency signal through holes 32A and 32B have a so-called via pad structure. By having such a via pad structure, the transmission distance of high-frequency signals between the antenna substrate 10 and the RFIC 20 can be made the shortest, and thus the transmission loss of high-frequency signals can be minimized.

[0073] In addition, as Figure 4 shown in (a) of, a circular conductor (hereinafter, for convenience, referred to as pad conductor LC3) is also formed on the second surface 30b of the component mounting substrate 30. The pad conductor LC3 is of a size similar to that of the pad conductors LC1 and LC2 and is insulated from the ground pattern 33. Through the pad conductor LC3, for example, the RFIC 20 mounted on the second surface 30b of the component mounting substrate 30 can be fixed.

[0074] As Figure 4 shown in (b) of, a solder resist 34 is formed on the second surface 30b of the component mounting substrate 30. A hole H1 is formed in the solder resist 34 to expose the high-frequency signal through holes 31a (including a part of the pad conductor LC1) of the pseudo coaxial structure through holes 31A and 31B to the outside. In addition, the diameter of the pad conductor LC1 is, for example, about 0.3 [mm], and the diameter of the hole H1 is, for example, about 0.2 [mm].

[0075] In addition, holes H2 are formed in the solder resist 34 to expose the non-high-frequency signal through holes 32A and 32B (including a part of the pad conductor LC2) to the outside. In addition, holes H3 are formed in the solder resist 34 to expose a part of the pad conductor LC3 and a part of the ground pattern 33 to the outside. In addition, the diameters of the pad conductors LC2 and LC3 are, for example, about 0.3 [mm], and the diameters of the holes H2 and H3 are, for example, about 0.2 [mm].

[0076] Here, the portions exposed to the outside through the holes H1, H2, and H3 are used as mounting pads for mounting the RFIC 20 on the second surface 30b of the component mounting substrate 30. These mounting pads are arranged at a certain pitch substantially within the plane of the second surface 30b of the component mounting substrate 30. Among them, as shown in (b) of Figure 4 , it is also possible to make the pitch of the mounting pads related to the hole H1 different from the pitch of the mounting pads related to the holes H2 and H3.

[0077] That is, it is possible to make the interval between the non-high-frequency signal through-holes 32A and 32B different from the interval between the high-frequency signal through-holes 31a of the pseudo coaxial structure through-holes 31A and 31B. This is because, for the pseudo coaxial structure through-holes 31A and 31B, in order to make their impedance match, there are cases where it is desired to adjust the distance between the high-frequency signal through-hole 31a and the ground through-hole 31b.

[0078] The antenna substrate 10 is positioned in such a way that each of the connection metal terminals 12a overlaps with each of the high-frequency signal through-holes 31a of the component mounting substrate 30 in a top view, and each of the connection metal terminals 12b overlaps with each of the non-high-frequency signal through-holes 32 of the component mounting substrate 30 in a top view, and is mounted on the first surface 30a of the component mounting substrate 30. The RFIC 20 is positioned in such a way that each of the metal terminals 21a overlaps with each of the high-frequency signal through-holes 31a of the component mounting substrate 30 in a top view, and each of the metal terminals 21b overlaps with each of the non-high-frequency signal through-holes 32 of the component mounting substrate 30 in a top view, and is mounted on the second surface 30b of the component mounting substrate 30.

[0079] The antenna substrate 10 and the RFIC 20 are respectively mounted on the first surface 30a and the second surface 30b of the component mounting substrate 30 in such a way that the entire RFIC 20 overlaps with the antenna substrate 10 in a top view, and are electrically connected through the high-frequency signal through-holes 31a and the non-high-frequency signal through-holes 32. In addition, the antenna substrate 10 and the RFIC 20 only need to overlap at least partially in a top view and be electrically connected through the high-frequency signal through-holes 31a provided in the overlapping portion.

[0080] As described above, the antenna module 1 of the present embodiment includes a component mounting substrate 30 provided with two pseudo coaxial structure through holes 31A and 31B arranged in a close configuration. When observing these pseudo coaxial structure through holes as a whole, the pseudo coaxial structure through holes 31A and 31B of the component mounting substrate 30 include two high-frequency signal through holes 31a and at least three ground through holes 31b arranged in parallel with respect to the high-frequency signal through holes 31a. One of the three ground through holes 31b is arranged in a region R1 between the two high-frequency signal through holes 31a. The other two ground through holes 31b are arranged in regions outside the region R1 in such a way that one ground through hole 31b is arranged in parallel with one high-frequency signal through hole 31a, and the other ground through hole 31b is arranged in parallel with the other first through hole 31a.

[0081] According to such a structure, the ground through hole 31b in the region R1 between the high-frequency signal through hole 31a of the pseudo coaxial structure through hole 31A and the high-frequency signal through hole 31a of the pseudo coaxial structure through hole 31B is designed to be shared by the pseudo coaxial structure through holes 31A and 31B. Thereby, the pseudo coaxial structure through holes 31 after impedance matching can be arranged with a higher density than before. In addition, by designing the ground through hole 31b arranged in the region R1 to be shared by the pseudo coaxial structure through holes 31A and 31B, the number of ground through holes 31b can be reduced by one, so that the cost can be correspondingly reduced.

[0082] <First Variant Example>

[0083] Figure 5 It is a cross-sectional view showing the component mounting substrate according to the first variant example. In addition, Figure 5 The cross-sectional view shown corresponds to the cross-sectional view along the Figure 1 A-A line of. In addition, in Figure 5 For the structure that is the same as the structure shown in Figure 2 The same reference numerals are given. In the example shown in Figure 2 For the sake of simplicity of explanation, an example in which two pseudo coaxial structure through holes 31 (31A, 31B) are arranged in a close configuration is described. However, the number of pseudo coaxial structure through holes 31 arranged in a close configuration may be three or more.

[0084] In Figure 5In the example shown, there are 4 pseudo coaxial structure through holes 31 (31B, 31C, 31D, 31E) arranged close to a pseudo coaxial structure through hole 31 (31A). In this example, the ground through hole 31b in the region R1 (not shown) between the high-frequency signal through holes 31a arranged in the pseudo coaxial structure through holes 31A and 31B is shared by the pseudo coaxial structure through holes 31A and 31B. In addition, the ground through hole 31b in the region R1 (not shown) between the high-frequency signal through holes 31a arranged in the pseudo coaxial structure through holes 31A and 31C is shared by the pseudo coaxial structure through holes 31A and 31C.

[0085] Similarly, the ground through hole 31b in the region R1 (not shown) between the high-frequency signal through holes 31a arranged in the pseudo coaxial structure through holes 31A and 31D is shared by the pseudo coaxial structure through holes 31A and 31D. In addition, the ground through hole 31b in the region R1 (not shown) between the high-frequency signal through holes 31a arranged in the pseudo coaxial structure through holes 31A and 31E is shared by the pseudo coaxial structure through holes 31A and 31E.

[0086] <Second Modified Example>

[0087] Figure 6 It is a cross-sectional view showing a component mounting substrate according to the second modified example. In addition, in Figure 6 the illustration of the antenna substrate 10 and the RFIC 20 is omitted, and only the portion of the component mounting substrate 30 where the pseudo coaxial structure through hole 31 is formed and its periphery are shown. In addition, in Figure 6 for structures identical to those shown in Figure 1 the same reference numerals are assigned.

[0088] As Figure 6 shown, in this modified example, a plurality of (3 layers in the example shown in Figure 6 ) ground patterns 33 are formed in the component mounting substrate 30. An opening AP that is formed in each ground pattern 33 and has a substantially circular shape with the periphery of the high-frequency signal through hole 31 provided in the pseudo coaxial structure through hole 31 hollowed out. In addition, each ground pattern 33 is electrically connected to the ground through hole 31b of the pseudo coaxial structure through hole 31.

[0089] As described above, in this modified example, the ground through hole 31b of the pseudo coaxial structure through hole 31 is strengthened by the plurality of (3 layers) ground patterns 33 formed in the component mounting substrate 30. Thereby, better impedance matching than in the above-described embodiment (where the ground pattern 33 in the component mounting substrate 30 is one layer) can be achieved.

[0090] <Third Modified Example>

[0091] Figure 7is a cross-sectional view showing the antenna module according to the third modification. Further, in Figure 7 structures identical to those shown in Figure 1 are labeled with the same reference numerals. The antenna module 1 according to this modification is different from the antenna module 1 shown in Figure 1 in that the ground pattern 33 in the component mounting substrate 30 is omitted.

[0092] The ground pattern 33 in the component mounting substrate 30 is preferably provided on the basis of the ground through-hole 31b that strengthens the pseudo coaxial structure through-hole 31. However, if there is no need to strengthen the ground through-hole 31b of the pseudo coaxial structure through-hole 31, as shown in Figure 7 , it can also be omitted.

[0093] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments and can be freely changed within the scope of the present invention.

[0094] For example, in the antenna module 1 in the above embodiment, only the antenna substrate 10 and the RFIC 20 are mounted on the component mounting substrate 30. However, other components (not shown) other than the antenna substrate 10 and the RFIC 20 may also be mounted on the component mounting substrate 30.

[0095] In addition, in the above embodiment, an example in which the antenna substrate 10 is mounted on the first surface 30a of the component mounting substrate 30 and the RFIC 20 is mounted on the second surface 30b of the component mounting substrate 30 has been described.

[0096] However, conversely, the RFIC 20 may be mounted on the first surface 30a of the component mounting substrate 30, and the antenna substrate 10 may be mounted on the second surface 30b of the component mounting substrate 30.

[0097] Explanation of reference numerals

[0098] 1... antenna module; 10... antenna substrate; 11... antenna; 20... RFIC; 30... component mounting substrate; 30a... first surface; 30b... second surface; 31a... high-frequency signal through-hole; 31b... ground through-hole; 32... non-high-frequency signal through-hole; 33... ground pattern; L1... straight line; LC1... pad conductor; R1... region.

Claims

1. A substrate having a through hole formed from a first surface to a second surface opposite to the first surface, wherein: The substrate includes: Two first through holes arranged in parallel with a predetermined interval therebetween and transmitting high-frequency signals; At least three second through holes for a reference potential, arranged in parallel with the two first through holes with an interval narrower than the predetermined interval; and A plurality of third through holes for transmitting non-high-frequency signals different from the high-frequency signals, Among the three second through holes, one second through hole is arranged in a region between the two first through holes, and the other two second through holes are arranged in regions other than the region between the first through holes in such a manner that: one of the other two second through holes is arranged in parallel with one of the two first through holes, and the other of the other two second through holes is arranged in parallel with the other of the two first through holes, The interval between the first through holes is different from the interval between the third through holes.

2. The substrate according to claim 1, wherein: The second through hole arranged in the region between the two first through holes is arranged at a position equidistant from each of the first through holes.

3. The substrate according to claim 1 or 2, wherein: The second through hole arranged in the region between the two first through holes is arranged on a straight line connecting the centers of the first through holes.

4. The substrate according to claim 1 or 2, wherein: The first through hole and the second through hole are arranged to have a pseudo coaxial structure after impedance matching.

5. The substrate according to claim 1 or 2, wherein: It further includes a ground pattern for impedance matching electrically connected to the second through hole.

6. The substrate according to claim 5, wherein: The ground pattern is provided with at least one layer inside the substrate.

7. The substrate according to claim 1 or 2, wherein: Electrode pads are formed at both ends of the first through hole.

8. An antenna module, wherein: The antenna module includes: An antenna substrate formed with an antenna; A high-frequency integrated circuit for processing high-frequency signals; and The substrate according to claim 1 or 2, The antenna substrate and the high-frequency integrated circuit are respectively mounted on the first surface and the second surface of the substrate in such a manner that at least a part thereof overlaps in a top view, and are electrically connected via the first through hole.

9. The antenna module according to claim 8, wherein: The substrate is formed of a material having a dielectric loss factor larger than that of the material of the antenna substrate.

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