Antenna system and antenna circuit board

Abstract

To provide an antenna system useful for communication at a high frequency.SOLUTION: An antenna system (100) is composed of a first glass layer (101) that transmits high-frequency waves, a low-dielectric layer (103) that has a lower dielectric constant than the first glass layer (101), is adjacent to the first glass layer (101), and transmits the high-frequency waves incident from the first glass layer (101), and an antenna circuit board (107) that is adjacent to the low-dielectric layer (103), receives the high-frequency waves incident from the low-dielectric layer (103), and includes a high-frequency insulating layer (105).SELECTED DRAWING: Figure 1

Description

Related Applications

[0001] This application claims the priority of Japanese Patent Applications No. 2019-218850 filed on December 3, 2019 and No. 2020-129756 filed on July 30, 2020, the entire disclosures of which are incorporated herein by reference in their entirety and made a part of this application.

Technical Field

[0002] The present invention relates to an antenna system useful for high-frequency communication and an antenna circuit board useful for this antenna system.

Background Art

[0003] It is known to dispose antennas for transmitting and receiving car phones and mobile phones on moving objects such as automobiles. For example, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2007-53505) describes that an antenna composed of conductive strips disposed on the window glass surface of a moving object such as an automobile or the surface of an insulating member of the body is suitable for receiving radio waves of UHF broadcast waves or VHF broadcast waves of television, and for transmitting and receiving broadband radio waves such as car phones, mobile phones, personal radios, business radios, and PHS.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, radio waves such as UHF broadcast waves, VHF broadcast waves, car phones, mobile phones, personal radios, business radios, and PHS have limitations in the amount of information that can be transmitted and cannot increase the amount of information. In recent years, the amount of information transmitted has been on the rise, and in order to exchange a large amount of information, it is necessary to use a high-frequency GHz band.

[0006] An object of the present invention is to provide an antenna system that is integrated with a glass layer and has excellent transmission characteristics in the GHz band. Another object of the present invention is to provide an antenna circuit board that has excellent transmission characteristics in the GHz band when communicating through a glass layer. Another object of the present invention is to provide a laminate of an antenna circuit board and a low dielectric layer that has excellent transmission characteristics in the GHz band when communicating through a glass layer.

Means for Solving the Problems

[0007] In order to achieve the above object, the inventors of the present invention considered using an antenna circuit board having high precision for high frequencies. However, at high frequencies, the transmission distance becomes short, so obstacles that did not affect in the conventional MHz band affect the antenna circuit board, and a new problem was found that the radio waves reaching the antenna circuit board are attenuated. Then, when a low dielectric layer having a dielectric constant lower than that of the glass is adjacent to the glass through which high frequencies penetrate and radio waves are made to reach the antenna circuit board through the low dielectric layer, it was found that high frequencies can be used with high accuracy, and the present invention was completed.

[0008] That is, the present invention can be configured in the following aspects. 〔Aspect 1〕 A first glass layer that transmits high frequencies, A low dielectric layer that has a dielectric constant lower than that of the first glass layer, is adjacent to the first glass layer, and transmits high frequencies incident from the first glass layer, An antenna circuit board including a high frequency insulating layer that is adjacent to the low dielectric layer and receives high frequencies incident from the low dielectric layer, An antenna system for use at a frequency of 1 GHz or higher (preferably 2 GHz or higher, more preferably 6 GHz or higher, still more preferably 30 GHz or higher, particularly preferably 50 GHz or higher) configured as described above. 〔Aspect 2〕 The antenna system according to aspect 1, wherein the high-frequency insulating layer is made of a thermoplastic liquid crystal polymer or polyimide. 〔Aspect 3〕 The antenna system according to aspect 1 or 2, wherein the dielectric constant εg of the first glass layer is 5.5 to 7.5 (preferably 5.8 to 7.3, more preferably 6.0 to 7.0), and the dielectric constant εf of the low-dielectric layer is 2.0 to 4.0 (preferably 2.2 to 3.5, more preferably 2.4 to 3.0), as the dielectric constants in both a direction in the plane and a direction perpendicular thereto, measured at a frequency of 28 GHz. 〔Aspect 4〕 The antenna system according to any one of aspects 1 to 3, wherein the dielectric loss tangent tanδg of the first glass layer is 0.05 or less (preferably 0.03 or less, more preferably 0.02 or less), and the dielectric loss tangent tanδf of the low-dielectric layer is 0.05 or less (preferably 0.03 or less, more preferably 0.01 or less), as the dielectric loss tangents in both a direction in the plane and a direction perpendicular thereto, measured at a frequency of 28 GHz. 〔Aspect 5〕 The antenna system according to any one of aspects 1 to 4, wherein the low-dielectric layer is composed of at least one selected from the group consisting of a polyvinyl acetal resin, an olefin-vinyl carboxylate copolymer resin, an ionomer resin, and an acrylic resin. 〔Aspect 6〕 The antenna system according to any one of aspects 1 to 5, wherein the dielectric constant εp of the high-frequency insulating layer is 2.0 to 4.0 (preferably 2.2 to 3.5, more preferably 2.4 to 3.0), as the dielectric constants in both a direction in the plane and a direction perpendicular thereto, measured at a frequency of 28 GHz. 〔Aspect 7〕 An antenna system according to any one of Aspects 1 to 6, wherein the dielectric loss tangent tanδp of the high-frequency insulating layer is 0.010 or less (preferably 0.005 or less, more preferably 0.003 or less) as the dielectric loss tangents in both a direction in a plane and a direction perpendicular thereto, measured at a frequency of 28 GHz. [Aspect 8] An antenna system according to any one of Aspects 1 to 7, wherein the dielectric constant εf of the low-dielectric layer and the dielectric constant εp of the high-frequency insulating layer satisfy εf / εp = 30 / 70 to 60 / 40 (preferably 35 / 65 to 60 / 40, more preferably 38 / 62 to 55 / 45). Antenna system. [Aspect 9] An antenna system according to any one of Aspects 1 to 8, wherein the thickness of the low-dielectric layer is λ / 4×n ± 0.050 mm (where λ is the wavelength of the high frequency and n is an integer) (preferably λ / 4×n ± 0.030 mm, more preferably λ / 4×n ± 0.025 mm). [Aspect 10] An antenna system according to any one of Aspects 1 to 9, wherein the first glass layer is composed of at least one selected from soda-lime glass, borate glass, borosilicate glass, aluminosilicate glass, quartz glass, alkali-free glass, and low-alkali glass. [Aspect 11] An antenna system according to any one of Aspects 1 to 10, further including a second glass layer, wherein a low-dielectric layer and an antenna circuit board are disposed between the first glass layer and the second glass layer. [Aspect 12] An antenna system according to any one of Aspects 1 to 11, which constitutes a window glass of a vehicle or a building. [Aspect 13] An antenna system according to any one of Aspects 1 to 11, for receiving radio waves while being attached to a vehicle, a building, or a civil engineering structure. [Aspect 14] An antenna circuit board for use in the antenna system according to any one of Aspects 1 to 13. [Aspect 15] A laminate including an antenna circuit board for use in the antenna system according to any one of Aspects 1 to 14 and a low dielectric layer adjacent to the antenna circuit board.

[0009] In addition, any combination of at least two components disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims described in the claims is included in the present invention. [Advantages of the Invention]

[0010] According to the present invention, in an antenna system, a high-frequency antenna circuit board is disposed, and a glass layer is disposed via a low dielectric layer with respect to this antenna circuit board, thereby suppressing high-frequency attenuation and enhancing the transmission characteristics of the antenna circuit board with respect to high frequencies, and enabling the exchange of a large amount of information. [Brief Description of the Drawings]

[0011] This invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and the drawings are for illustrative and explanatory purposes only and should not be used to define the scope of this invention. The scope of this invention is determined by the appended claims. In the accompanying drawings, the same part numbers in a plurality of drawings indicate the same parts. The drawings are not necessarily shown at a constant scale and are exaggerated for showing the principle of the present invention.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0012] The antenna system of the present invention includes at least a first glass layer that transmits high-frequency waves, a low-dielectric layer that has a lower dielectric constant than the first glass layer, is adjacent to the first glass layer, and transmits the high-frequency waves incident from the first glass layer, and an antenna circuit board that is adjacent to the low-dielectric layer and receives the high-frequency waves incident from the low-dielectric layer.

[0013] The frequency of the high-frequency waves targeted by the antenna system of the present invention is, for example, 1 GHz or higher, preferably 2 GHz or higher, more preferably 6 GHz or higher, still more preferably 30 GHz or higher, and particularly preferably 50 GHz or higher. The upper limit of the frequency is not particularly limited, but it may be, for example, 400 GHz or lower, preferably 300 GHz or lower.

[0014] Hereinafter, examples of specific embodiments of the antenna system of the present invention will be described with reference to the drawings, but the antenna system of the present invention is not limited to the illustrated embodiments.

[0015] [First Embodiment] FIG. 1 is a schematic cross-sectional view for explaining a manufacturing method of an antenna system according to a first embodiment. As shown in FIG. 1, an antenna system 100 according to the first embodiment includes a first glass layer 101, a low dielectric layer 103 having a dielectric constant lower than that of the first glass layer 101, and an antenna circuit board 107. The first glass layer 101 and the low dielectric layer 103 have portions adjacent to each other in the thickness direction, and the low dielectric layer 103 and the antenna circuit board 107 have portions adjacent to each other in the thickness direction.

[0016] In FIG. 1, only one antenna circuit board is disposed. However, one or more (for example, 1 to 10, etc.) antenna circuit boards may be included in one antenna system adjacent to the low dielectric layer. When a plurality of antenna circuit boards are included, it may be multi-band compatible including a non-high-frequency antenna circuit board (a circuit board targeting frequencies less than 1 GHz). This is the same in the following embodiments.

[0017] The first glass layer 101 may be, for example, window glass or the like. Note that the position of the antenna circuit board in the plane of the window glass is not particularly limited. For example, as shown in FIG. 1, one end of the antenna circuit board 107 may be disposed in contact with an end of the window glass, or the one end (the outermost end of the antenna circuit board) of the antenna circuit board 107 may be disposed inward from the end of the window glass (for example, about 1 to 10 cm inward). Also, similar to the window glass, the antenna circuit board may be disposed on vehicle glass (front glass, side glass, rear glass).

[0018] For example, when visibility is required, such as in the case of window glass or automotive glass, it is preferable to arrange the antenna circuit board 107 in a portion that does not obstruct the field of view. For example, the antenna circuit in the antenna circuit board 107 may be arranged in an end region that is 0 cm or more and 10 cm or less inward from the end of the first glass layer 103. Also, in order to prevent rust or the like from occurring due to water absorption from the end, the antenna circuit in the antenna circuit board 107 may be arranged away from the end of the first glass layer 103. For example, it may be arranged in an end region that is 1 cm or more inward from the end of the first glass layer 103 (preferably in a region that is 1 cm or more and 10 cm or less inward). These are the same in the following embodiments.

[0019] In FIG. 1, the high-frequency wave A indicated by the one-end arrow toward the first glass layer 101 is incident on the first glass layer 101 from the outside and exits to the inside thereof. Therefore, in the thickness direction Z indicated by the double-arrow, the first glass layer 101 has one as the outer surface and the other as the inner surface. Adjacent to the inside in the thickness direction Z of the first glass layer 101 is a low-dielectric layer 103, and adjacent to the inside in the thickness direction Z of the low-dielectric layer 103 is an antenna circuit board 107.

[0020] After the high-frequency wave A is incident from the outer surface of the first glass layer 101, it reaches the antenna circuit board 107 through the low-dielectric layer 103 adjacent to the first glass layer 101. Then, the high-frequency wave A that has reached the antenna circuit board 107 is received by the antenna circuit board 107. Note that in this specification, even in the form where only reception is described, not only reception but also transmission is possible, and this is the same in all embodiments.

[0021] The antenna circuit board 107 includes a high-frequency insulating layer (hereinafter sometimes simply referred to as the insulating layer) 105, a circuit layer 104 disposed on one surface (the outer surface in the thickness direction Z) of the insulating layer 105, and a conductor layer 106 disposed on the other surface (the inner surface in the thickness direction Z) of the insulating layer 105. In FIG. 1, for simplicity, only one layer of the circuit layer is shown, but since the insulating layer may include inner layer circuits (not shown) and the like, the antenna circuit board 107 may be a multilayer circuit board. Also, the conductor layer 106 may have a circuit pattern as required, or may be a metal layer having reflectivity or the like. In the conductor layer 106, when the high-frequency wave A incident on the antenna circuit board 107 is reflected by the metal layer having reflectivity, the utilization efficiency of the high-frequency wave A in the antenna circuit board 107 can be improved.

[0022] The high-frequency wave A has a wavelength λ at a predetermined frequency. After entering the first glass layer 101, a part of it is reflected without reaching the antenna circuit board 107. However, by making the dielectric constant εf of the low-dielectric layer 103 smaller than the dielectric constant εg of the first glass layer 101, the reflectance R from when the high-frequency wave A enters the first glass layer 101 until it reaches the surface of the antenna circuit board 107 can be reduced, and the ratio of the high-frequency wave A reaching the antenna circuit board 107 can be increased.

[0023] In the antenna system 100, in the thickness direction Z, the first glass layer 101 has a thickness dg, the low-dielectric layer 103 has a thickness df on the antenna circuit board 107, and the insulating layer 105 in the antenna circuit board 107 has a thickness dp. Here, when the ratio of the thickness df of the low-dielectric layer 103 occupying in the plane of the circuit portion (circuit layer 104) is less than half, it is grasped as the distance between the first glass layer 101 and the insulating layer 105 ignoring the circuit portion, but for convenience, it is referred to as the thickness df of the low-dielectric layer 103. Note that the thickness df on the antenna circuit board 107 may be the thickness of the low-dielectric layer disposed on the incident side of the high-frequency wave A with respect to the antenna circuit board.

[0024] The thickness dg of the first glass layer 101 can be appropriately set according to the use of the object provided with the first glass layer, for example, from the range of 0.1 to 100 mm. For example, it may be about 0.5 to 20 mm (for example, 1 to 20 mm), preferably about 1 to 15 mm (for example, 3 to 13 mm), and more preferably about 1.5 to 10 mm (for example, 4 to 10 mm). For example, the first glass layer 101 may be the first glass layer of a vehicle or the first glass layer of a building, or may be the first glass layer forming laminated glass.

[0025] The thickness dp of the insulating layer 105 in the antenna circuit board 107 can be appropriately set according to the required antenna performance and the like, and can be selected from a wide range of, for example, 10 μm to 2.5 mm. For example, it may be about 0.1 to 2.5 mm, preferably about 0.3 to 2.0 mm, and more preferably about 0.3 to 1.0 mm. When the antenna circuit board is a multilayer circuit board, the thickness dp of the insulating layer indicates the total thickness of the insulating layers constituting the multilayer circuit board (or the total thickness of all the insulating layers).

[0026] In FIG. 1, the low dielectric layer 103 has adhesiveness to both the first glass layer 101 and the antenna circuit board 107, and the antenna circuit board 107 is attached to the first glass layer 101 via the low dielectric layer 103. Therefore, the low dielectric layer 103 has a surface in close contact with the first glass layer 101, and the antenna circuit board 107 has a surface in close contact with the low dielectric layer 103.

[0027] The low dielectric layer 103 may have a desired size according to the application with respect to the antenna circuit board 107. As shown in FIG. 1, the dimensions of the low dielectric layer 103 in the plane direction may be the same as those of the antenna circuit board 107, or may be smaller or larger. When the low dielectric layer 103 is larger in the plane direction than the antenna circuit board 107, the low dielectric layer 103 may embed the antenna circuit board 107. Note that the plane direction is the plane direction with the thickness direction Z in FIG. 1 as the normal. The dimensions of the low dielectric layer and the high-frequency antenna circuit board are common also in the following embodiments.

[0028] Note that when the low dielectric layer 103 does not have adhesiveness, the first glass layer 101, the low dielectric layer 103, and the antenna circuit board 107 may be adjacent to each other using external adhesion means as necessary. In that case, it is preferable that the adjacent surfaces between the low dielectric layer 103 and the first glass layer 101 are in close contact without an air layer therebetween. Similarly, it is preferable that the adjacent surfaces between the low dielectric layer 103 and the antenna circuit board 107 are in close contact without an air layer therebetween.

[0029] In the first glass layer 101, the antenna circuit board 107 can be disposed at a desired location with a desired size according to the application.

[0030] Note that a protection member for protecting the antenna circuit board 107 may be disposed on the back surface (that is, the surface opposite to the surface in contact with the low dielectric layer 103) and / or the side surface of the antenna circuit board 107 as necessary. For example, as the protection member, for example, an additional low dielectric layer may be disposed adjacent to the antenna circuit board 107. Or, as the protection member, for example, an additional low dielectric layer and a second glass layer may be disposed adjacent to the antenna circuit board 107 in this order. Also, when the antenna system 100 is used for vehicle glass or the like, a sealing material may be provided at at least a part of the edge of the first glass layer 103. These are the same in the following embodiments.

[0031] [Second Embodiment] FIG. 2 is a schematic cross-sectional view for explaining a method of manufacturing an antenna system according to a second embodiment. As shown in FIG. 2, an antenna system 200 according to the second embodiment includes a first glass layer 201, a low dielectric layer 203 having a dielectric constant lower than that of the first glass layer 201, an antenna circuit board 107, and a second glass layer 202 disposed opposite to the first glass layer 201 in the thickness direction Z. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The antenna system 200 may be, for example, a multilayer glass (or laminated glass) formed by the first glass layer 201 and the second glass layer 202, and may be a window glass or a vehicle glass (front glass, side glass, rear glass) made of the multilayer glass. The antenna circuit board 107 may be disposed inside the first glass layer 201 and the second glass layer 202 via the low dielectric layer 103.

[0032] In the second embodiment, the low dielectric layer 203 embeds the antenna circuit board 107, and the first glass layer 201 and the second glass layer 202 are bonded by the low dielectric layer 203.

[0033] The high-frequency wave A has a wavelength λ at a predetermined frequency. After entering the first glass layer 201, a part of the high-frequency wave A is reflected by a predetermined reflectance R without reaching the antenna circuit board 107. By making the dielectric constant εf of the low dielectric layer 203 smaller than the dielectric constant εg of the first glass layer 201, the reflectance R can be reduced, and the ratio of the high-frequency wave A reaching the antenna circuit board 107 can be improved.

[0034] In the antenna system 200, in the thickness direction Z, the first glass layer 201 has a thickness dg, the low dielectric layer 203 has a thickness df on the antenna circuit board 107, and the insulating layer 105 in the antenna circuit board 107 has a thickness dp. Here, the thickness df of the low dielectric layer 203 is understood as the distance between the first glass layer 201 and the insulating layer 105, rather than the distance between the first glass layer 201 and the second glass layer 202. Note that the overall thickness da of the low dielectric layer 203 means the thickness of the entire low dielectric layer, and in FIG. 2, it shows the distance between the first glass layer 201 and the second glass layer 202. These are the same in all embodiments.

[0035] The thickness dg of the first glass layer 201 can be appropriately set according to the use of the object provided with the first glass layer. For example, it may be about 0.5 to 20 mm (for example, 1 to 20 mm), preferably about 1 to 15 mm (for example, 3 to 13 mm), and more preferably about 1.5 to 10 mm (for example, 4 to 10 mm).

[0036] Regarding the thickness dg' of the second glass layer 202, it can also be appropriately set according to the use of the object provided with the second glass layer 202. For example, it may be about 0.5 to 20 mm (for example, 1 to 20 mm), preferably about 1 to 15 mm (for example, 3 to 13 mm), and more preferably about 1.5 to 10 mm (for example, 4 to 10 mm).

[0037] In the first glass layer 201, the antenna circuit board 107 can be arranged at a desired size and at a desired location according to the use.

[0038] [Third Embodiment] FIG. 3 is a schematic cross-sectional view for explaining a method of manufacturing an antenna system according to the third embodiment. As shown in FIG. 3, an antenna system 300 according to the third embodiment includes a first glass layer 301, a low dielectric layer 303 having a dielectric constant lower than that of the first glass layer 301, an antenna circuit board 107, and a second glass layer 302. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The first glass layer 301 and the low dielectric layer 303 have a portion adjacent to each other in the thickness direction, and the low dielectric layer 303 and the antenna circuit board 107 have a portion adjacent to each other in the thickness direction. Further, the antenna circuit board 107 may be attached to the second glass layer 302 by various fixing means. For example, the antenna circuit board 107 may be attached to the second glass layer 302 via an adhesive layer 308.

[0039] In this embodiment, the second glass layer 302 may be, for example, a window glass or the like, and the antenna circuit board 107 may be disposed outside the window glass.

[0040] In the third embodiment, after the high-frequency wave A enters the first glass layer 301, a part of it is reflected with a predetermined reflectance R without reaching the antenna circuit board 107. By making the dielectric constant εf of the low dielectric layer 303 smaller than the dielectric constant εg of the first glass layer 301, the reflectance R can be reduced, and the ratio of the high-frequency wave A reaching the antenna circuit board 107 can be improved.

[0041] In the antenna system 300, the first glass layer 301 has a thickness dg in the thickness direction Z, the low dielectric layer 303 has a thickness df, and the insulating layer 105 in the antenna circuit board 107 has a thickness dp. Here, the thickness df of the low dielectric layer 303 is understood as the distance between the first glass layer 301 and the insulating layer 305, not the distance between the first glass layer 301 and the second glass layer 302. Note that in this embodiment, the overall thickness of the low dielectric layer 303 is the same as the thickness df on the antenna circuit board 107.

[0042] The first glass layer 301 may be thin from the perspective of weight reduction, and the thickness dg may be, for example, about 0.5 to 7 mm, preferably about 0.7 to 5 mm, more preferably about 0.8 to 3 mm.

[0043] The thickness dg' of the second glass layer 302 can be appropriately set according to the use of the object to which the second glass layer 302 is attached. For example, it may be about 0.5 to 20 mm (for example, 1 to 20 mm), preferably about 1 to 15 mm (for example, 3 to 13 mm), more preferably about 1.5 to 10 mm (for example, 4 to 10 mm).

[0044] When the adhesive layer 308 is provided, as long as the adhesive layer 308 can adhere the antenna circuit board 107 to the second glass layer, a known or conventional adhesive material having adhesiveness to the antenna circuit board and the glass can be used. Also, as the adhesive layer 308, an adhesive material used for a low dielectric layer may be used. Or, from the perspective of simplification, 308 may be a pressure-sensitive adhesive tape such as a double-sided tape.

[0045] In the second glass layer 302, the antenna circuit board 107 can be arranged in a desired size and at a desired location according to the use.

[0046] [Fourth Embodiment] FIG. 4 is a schematic cross-sectional view for explaining a method of manufacturing an antenna system according to the fourth embodiment. As shown in FIG. 4, the antenna system 400 according to the fourth embodiment includes a first glass layer 401, a low dielectric layer 403 having a lower dielectric constant than the first glass layer 401, and an antenna circuit board 107. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[0047] The first glass layer 401 and the low dielectric layer 403 have portions adjacent to each other in the thickness direction, and the low dielectric layer 403 and the antenna circuit board 107 have portions adjacent to each other in the thickness direction.

[0048] In this embodiment, the adherend 409 can be of various types as long as it can fix the antenna circuit board 107. For example, it may be a wall portion of a building or a side portion of a vehicle. Also, the adherend 409 may be a flexible material such as a PEN film, a PET film, or an acrylic film.

[0049] In the fourth embodiment, after the high-frequency wave A is incident on the first glass layer 401, a part of it is reflected with a predetermined reflectance R without reaching the antenna circuit board 107. By making the dielectric constant εf of the low-dielectric layer 403 smaller than the dielectric constant εg of the first glass layer 401, the reflectance R can be reduced, and the ratio of the high-frequency wave A reaching the antenna circuit board 107 can be improved.

[0050] In the antenna system 400, in the thickness direction Z, the first glass layer 401 has a thickness dg, the low-dielectric layer 403 has a thickness df, and the insulating layer 105 in the antenna circuit board 107 has a thickness dp. Here, the thickness df of the low-dielectric layer 403 is understood as the distance between the first glass layer 401 and the insulating layer 105. In this embodiment, the overall thickness of the low-dielectric layer 403 is the same as the thickness df on the antenna circuit board 107.

[0051] The first glass layer 401 may be thin from the viewpoint of weight reduction, and the thickness dg may be, for example, about 0.5 to 7 mm, preferably about 0.7 to 5 mm, and more preferably about 0.8 to 3 mm.

[0052] Furthermore, the antenna system 400 may be attached to the adherend 409 by various fixing means. For example, the antenna system 400 may be attached to the adherend 409 using fixing means 408a and 408b that surround the antenna system 400 from the side. The fixing means 408a and 408b may be separate members or integrated members. The fixing means may include bolts, screws, nuts, etc.

[0053] In addition to, or instead of, the fixing means 408a and 408b, although not shown, the antenna circuit board 107 and the adherend 409 may be adhered via an adhesive layer such as the adhesive layer 308 shown in FIG. 3.

[0054] For example, as long as the adhesive layer can adhere the antenna circuit board 107 to the adherend 409, known or conventional adhesive materials having adhesiveness to the antenna circuit board and the adherend can be used. For example, from the viewpoint of simplification, the adhesive layer may be a pressure-sensitive adhesive material such as a double-sided tape.

[0055] In the adherend 409, the antenna circuit board 107 can be disposed at a desired size and at a desired location according to the application.

[0056] [Fifth Embodiment] FIG. 5 is a schematic cross-sectional view for explaining an antenna system according to the fifth embodiment. As shown in FIG. 5, the antenna system 500 according to the fifth embodiment includes a first glass layer 501, a first low dielectric layer 503a having a lower dielectric constant than the first glass layer 501, an antenna circuit board 107, a second low dielectric layer 503b, and a second glass layer 502 disposed opposite to the first glass layer 501 in the thickness direction Z. Note that the same components as those in the fifth embodiment are denoted by the same reference numerals, and the description thereof is omitted. The antenna system 500 may be, for example, a laminated glass formed by the first glass layer 501 and the second glass layer 502, such as a window glass made of laminated glass, or the antenna circuit board 107 may be disposed inside the first glass layer 501 and the second glass layer 502 via the first low dielectric layer 503a and the second low dielectric layer 503b.

[0057] In the fifth embodiment, the antenna circuit board 107 is embedded at the boundary between the first low dielectric layer 503a and the second low dielectric layer 503b, and the first glass layer 501 and the second glass layer 502 are adhered by the first low dielectric layer 503a and the second low dielectric layer 503b to form a laminated glass.

[0058] The high-frequency wave A has a wavelength λ at a predetermined frequency. After entering the first glass layer 501, a part of it is reflected by a predetermined reflectance R without reaching the antenna circuit board 107. However, by using the first low-dielectric layer 503a and making the dielectric constant εf of the first low-dielectric layer 503a smaller than the dielectric constant εg of the first glass layer 501, the reflectance R can be reduced, and the ratio of the high-frequency wave A reaching the antenna circuit board 107 can be improved.

[0059] In the antenna system 500, in the thickness direction Z, the first glass layer 501 has a thickness dg, the first low-dielectric layer 503a has a thickness df on the antenna circuit board 107, and the insulating layer 105 in the antenna circuit board 107 has a thickness dp. Here, the thickness df of the first low-dielectric layer 503a on the antenna circuit board 107 is grasped as the distance between the first glass layer 501 and the insulating layer 105.

[0060] Also, the second low-dielectric layer 503b has a thickness df' under the high-frequency antenna circuit board 107. Since the ratio of the thickness df' of the second low-dielectric layer 503b under the high-frequency antenna circuit board 107 occupying the in-plane of the conductive layer 106 is more than half, it is grasped as the distance between the second glass layer 501 and the conductive layer 106. Note that the thickness df' under the antenna circuit board 107 may be the thickness of the low-dielectric layer disposed on the side opposite to the first low-dielectric layer with respect to the antenna circuit board. Also, the first and second low-dielectric layers are integrated, and the total thickness of the low-dielectric layer is grasped as the thickness da, which is the distance between the first glass layer 501 and the second glass layer 502.

[0061] The thickness dg of the first glass layer 501 can be appropriately set according to the use of the object provided with the first glass layer 501. For example, it may be about 0.5 to 20 mm, preferably about 1 to 15 mm, and more preferably about 1.5 to 10 mm.

[0062] Regarding the thickness dg' of the second glass layer 502 as well, it can be appropriately set according to the use of the object provided with the second glass layer 502. For example, it may be about 0.5 to 20 mm, preferably about 1 to 15 mm, and more preferably about 1.5 to 10 mm.

[0063] The thickness df of the first low dielectric layer 503a and the thickness df' of the second low dielectric layer 503b may be the same as each other or different from each other.

[0064] In the first glass layer 501, the antenna circuit board 107 can be arranged at a desired size and at a desired location according to the use.

[0065] [Sixth Embodiment] FIG. 6 is a schematic cross-sectional view for explaining the antenna system according to the sixth embodiment. As shown in FIG. 6, the antenna system 600 according to the sixth embodiment includes a first glass layer 601, a first low dielectric layer 603a having a lower dielectric constant than the first glass layer 601, an antenna circuit board 107, a second low dielectric layer 603b, and a second glass layer 602 disposed opposite to the first glass layer 601 in the thickness direction Z. Note that the same components as those in the fifth embodiment are denoted by the same reference numerals, and the description thereof is omitted. The antenna system 600 may be, for example, a laminated glass formed by the first glass layer 601 and the second glass layer 602, such as a window glass made of laminated glass, or a state in which the antenna circuit board 107 is disposed inside the first glass layer 601 and the second glass layer 602 via the first low dielectric layer 603a and the second low dielectric layer 603b.

[0066] In the sixth embodiment, the antenna circuit board 107 is embedded in a thick first low-dielectric layer 603a together with a thin second low-dielectric layer 603b. The second low-dielectric layer 603b is in contact with the first low-dielectric layer 603a on a surface that is not in contact with either the antenna circuit board or the second glass layer. The first low-dielectric layer 603a and the second low-dielectric layer 603b together form the low-dielectric layer 603 as a whole, and the first glass layer 601 and the second glass layer 602 are adhered by the low-dielectric layer 603 to form a laminated glass.

[0067] The high-frequency wave A has a wavelength λ at a predetermined frequency. After entering the first glass layer 601, a part of it is reflected with a predetermined reflectance R without reaching the antenna circuit board 107. However, by using the first low-dielectric layer 603a to make the dielectric constant εf of the first low-dielectric layer 603a smaller than the dielectric constant εg of the first glass layer 601, the reflectance R can be reduced, and the ratio of the high-frequency wave A reaching the antenna circuit board 107 can be improved.

[0068] In the antenna system 600, in the thickness direction Z, the first glass layer 601 has a thickness dg, the first low-dielectric layer 603a has a thickness df on the antenna circuit board 107, and the insulating layer 105 in the antenna circuit board 107 has a thickness dp. Here, since the thickness df of the first low-dielectric layer 603a on the antenna circuit board 107 is less than half of the proportion occupied in the plane of the circuit portion (circuit layer 104), it is grasped as the distance between the first glass layer 601 and the insulating layer 105.

[0069] Also, the second low-dielectric layer 603b has a thickness df' under the antenna circuit board 107. Since the thickness df' of the second low-dielectric layer 603b under the antenna circuit board 107 is more than half of the proportion occupied in the plane of the conductive layer 106, it is grasped as the distance between the second glass layer 602 and the conductive layer 106.

[0070] The thickness dg of the first glass layer 601 can be appropriately set according to the use of the object provided with the first glass layer 601. For example, it may be about 0.5 to 20 mm, preferably about 1 to 15 mm, and more preferably about 1.5 to 10 mm.

[0071] Regarding the thickness dg' of the second glass layer 602 as well, it can be appropriately set according to the use of the object provided with the second glass layer 602. For example, it may be about 0.5 to 20 mm, preferably about 1 to 15 mm, and more preferably about 1.5 to 10 mm.

[0072] The antenna circuit board 107 and the second low dielectric layer 603b may be embedded in the first low dielectric layer 603a. In this case, the thickness df of the first low dielectric layer 603a above the antenna circuit board 107 may be made sufficiently thicker than the thickness df' of the second low dielectric layer 603b.

[0073] In FIG. 6, when the overall thickness da of the first and second low dielectric layers is such that the first low dielectric layer 603a has substantially the same thickness before and after embedding the antenna circuit board 107 and the second low dielectric layer 603b, the film thickness of the first low dielectric layer 603a may be used as the overall thickness da of the first and second low dielectric layers.

[0074] In the first glass layer 601, the antenna circuit board 107 can be arranged at a desired size and at a desired location according to the use.

[0075] Furthermore, the present invention also includes a laminate including an antenna circuit board for use in the above-described antenna system and the like, and a low dielectric layer adjacent to the antenna circuit board. The laminate of the present invention may include an antenna circuit board and a low dielectric layer adjacent to the antenna circuit board. For example, as the laminate, there may be mentioned a laminate in which a first low dielectric layer and an antenna circuit board are laminated in this order, a laminate in which a first low dielectric layer, an antenna circuit board, and a second low dielectric layer are laminated in this order, and the like. The laminate may further form a third layer such as a protective layer with respect to these laminates. The laminate may be combined with an adherend such as glass to form an antenna system. For example, such a laminate may constitute a part of the antenna system described in the first to sixth embodiments described above.

[0076] Hereinafter, each component will be described, but these are merely examples, and various aspects can be included as long as the effects of the present invention can be achieved.

[0077] (First and second glass layers) The shape of the first and second glass layers is not particularly limited as long as high-frequency waves can reach the antenna circuit board through the low dielectric layer after passing through the high-frequency waves. For example, planar glass such as planar or curved glass can be mentioned.

[0078] Further, the material of the first and second glass layers is not particularly limited as long as it is generally a material used for window glass or the like, and various translucent transparent or translucent organic glass members (for example, acrylic members, polycarbonate members, etc.) may be used. However, from the viewpoints of weather resistance and transparency, inorganic glass members such as soda-lime glass, borate glass, borosilicate glass, aluminosilicate glass, and quartz glass are preferable. According to the classification by the alkali component, non-alkali glass and low-alkali glass can be mentioned. The content of the alkali metal component (for example, Na2O, K2O, Li2O) of the above glass member is preferably 15% by weight or less, and more preferably 10% by weight or less.

[0079] The forming method of these glass layers can adopt any appropriate method according to the shape and material of the glass. Typically, the glass member is made by melting a mixture containing main raw materials such as silica and alumina, defoaming agents such as sodium sulfate and antimony oxide, and reducing agents such as carbon at a temperature of 1400°C to 1600°C, forming it into a thin plate shape, and then cooling it. Examples of the thin plate forming method of the glass member include the slot down draw method, the fusion method, the float method, etc. The glass formed into a predetermined shape such as a plate shape by these methods may be thinned or an uneven shape may be imparted to the surface by an antiglare treatment or the like as necessary. Also, in order to enhance smoothness, it may be chemically polished with a solvent such as hydrofluoric acid.

[0080] The first and second glass layers may be, for example, window glasses for vehicles (for example, window glasses for vehicles such as cars, railways, airplanes, ships, etc.), or window glasses for buildings.

[0081] Also, the second glass layer may be combined with the first glass layer, and an antenna circuit board may be disposed therebetween. Generally, the second glass layer is a glass member disposed opposite to the first glass layer in the thickness direction, and the second glass layer may be made of the same material as the first glass layer or a different material.

[0082] The first and second glass layers may include a colored region, and the antenna circuit in the antenna circuit board may be disposed within the colored region. The colored region of the first and / or second glass layer may be partially (for example, an end region, etc.) when visibility is required, particularly in the case of window glasses or vehicle glasses.

[0083] (Low dielectric layer) The low dielectric layer has a lower dielectric constant than the first glass layer and has the role of allowing the high frequency incident from the first glass layer to reach the antenna circuit board. The low dielectric layer has a smaller dielectric constant than the first glass layer when compared at the same frequency. Preferably, the dielectric constant εf of the low dielectric layer preferably exists within the range of the following formula (I) with respect to the dielectric constant εg of the first glass layer.

[0084]

Number

[0085] As specific values, for example, at a frequency of 28 GHz, with respect to the dielectric constant εg of the first glass layer, the dielectric constant εf of the low dielectric layer may be, for example, εg - 5 to εg - 0.1, preferably εg - 4.5 to εg - 0.5, more preferably εg - 4 to εg - 1.5.

[0086] Note that the measurement of dielectric properties (dielectric constant and dielectric tangent) can be performed in accordance with JIS R 1660 - 2 at 28 GHz (25 °C) using a Fabry - Perot resonator (Model No. DPS03) manufactured by Keycom Co., Ltd. This measurement method can measure with very high precision in both the one - direction in the plane and the direction perpendicular thereto (X - Y direction), and even for materials with a low tanδ, high - precision measurement is possible.

[0087] In one aspect, for example, at a frequency of 28 GHz, the dielectric constant εg of the first glass layer may be 5.5 to 7.5, preferably 5.8 to 7.3, more preferably 6.0 to 7.0, and the dielectric constant εf of the low dielectric layer may be, for example, 2.0 to 4.0, preferably 2.2 to 3.5, more preferably 2.4 to 3.0.

[0088] In one aspect, for example, at a frequency of 28 GHz, the dielectric tangent tanδg of the first glass layer may be 0.05 or less, preferably 0.03 or less, more preferably 0.02 or less, and the dielectric tangent tanδf of the low dielectric layer may be, for example, 0.05 or less, preferably 0.03 or less, more preferably 0.01 or less.

[0089] In one aspect, the thickness (df: unit mm) of the low dielectric layer may be in the range of λ / 4×n - 0.050 to λ / 4×n + 0.050 with respect to the wavelength λ (range: 1 to 100 mm) of the high frequency, preferably in the range of λ / 4×n - 0.030 to λ / 4×n + 0.030, more preferably in the range of λ / 4×n - 0.025 to λ / 4×n + 0.025, and particularly preferably in the range of λ / 4×n - 0.010 to λ / 4×n + 0.010. Here, n is an integer (for example, an integer from 1 to 10).

[0090] In one aspect, the thickness (df: unit mm) of the low dielectric layer can be appropriately changed according to the wavelength (λ) of the high frequency and the dielectric constant εf of the low dielectric layer, and preferably satisfies any of the following formulas (II) to (II''). Here, n is an integer (for example, an integer from 1 to 10).

[0091]

Number

[0092] More preferably, it may be in the range that satisfies the following formula (II').

Number

[0093] More preferably, it may be in the range that satisfies the following formula (II'').

Number

[0094] In one aspect, the thickness (df: unit mm) of the low dielectric layer on the antenna circuit board can be appropriately changed according to the wavelength (λ) of the high frequency and the dielectric constant of the low dielectric layer, and preferably satisfies any of the following formulas (III) to (III''). Here, n is an integer (for example, an integer from 1 to 10).

[0095]

Number

[0096] More preferably, it may be in a range satisfying the following formula (III’).

Number

[0097] More preferably, it may be in a range satisfying the following formula (III’’).

Number

[0098] In one aspect, the thickness df of the low dielectric layer can be selected from a wide range of about 1 μm to 20.0 mm. From the viewpoint of suppressing reflectivity, for example, it may be about 0.1 to 20.0 mm, preferably about 0.1 to 10.0 mm, more preferably about 0.15 to 2.0 mm.

[0099] Also, when the low dielectric layer is used for the laminated glass, etc., the thickness df of the low dielectric layer may be in a thick range. In that case, the thickness df of the low dielectric layer may exceed, for example, 0.37 mm, preferably 0.50 mm or more, more preferably 0.75 mm or more, and may preferably be 2.5 mm or less, more preferably 2.28 mm or less, further preferably 1.6 mm or less, and even more preferably 0.85 mm or less.

[0100] On the other hand, depending on the application, the low dielectric layer may be thin. For example, the thickness df of the low dielectric layer may be, for example, 370 μm or less, more preferably 300 μm or less, further preferably 200 μm or less, even more preferably 100 μm or less, particularly preferably 60 μm or less, particularly more preferably less than 50 μm, particularly further preferably 45 μm or less, and most preferably 40 μm or less. Also, it is preferably 1 μm or more, more preferably 5 μm or more, further preferably 10 μm or more, and even more preferably 20 μm or more.

[0101] When a first low dielectric layer and a second low dielectric layer are adjacent to each other on both sides of the antenna circuit board, respectively, the thickness df of the first low dielectric layer and the thickness df' of the second low dielectric layer may both be in the thick range, may both be in the thin range, or one may be in the thick range and the other may be in the thin range.

[0102] Also, in one aspect, when a first low dielectric layer and a second low dielectric layer are adjacent to each other on both sides of the antenna circuit board, respectively, depending on the aspect and application of the antenna system, the thickness and the size in the plane direction of each low dielectric layer may be the same as each other or may be different from each other. When making one of the low dielectric layers extremely thin with respect to the other, for example, the thickness ratio (df / df' where df > df') of the thick low dielectric layer to the thin low dielectric layer may be 3 / 1 to 30 / 1, preferably 4 / 1 to 20 / 1. When having such a thickness ratio, for example, when forming a laminated glass in which the antenna circuit board is disposed inside the thick low dielectric layer, it is possible to produce the laminated glass without boring a middle film for laminated glass to fill a step or using a spacer for filling a step.

[0103] Although it can be appropriately set according to the application and the thickness of the circuit board, for example, when the first and second low dielectric layers are integrated, the total thickness da of the low dielectric layer may be about 0.1 to 40 mm, preferably about 0.5 to 30 mm, more preferably about 1.0 to 25 mm.

[0104] The low dielectric layer has a predetermined dielectric constant and is not particularly limited as long as it can be adjacent to the first glass layer. For example, it may be formed of a thermoplastic resin or a thermosetting resin having a predetermined dielectric constant. Here, "adjacent" means being in close contact on the adjacent surface of the object, or being in proximity within a range where the incident rate of high frequency is maintained at about the same level (for example, within a range of ±10% of the incident rate when in close contact) compared to the case of being in close contact.

[0105] Since the interfaces between the first glass layer and the low dielectric layer and between the low dielectric layer and the antenna circuit board can be easily adhered, it is preferable that the low dielectric layer itself is an adhesive low dielectric layer having adhesiveness. The low dielectric layer may have adhesiveness to the first glass layer, may have adhesiveness to the antenna circuit board, and preferably has adhesiveness to both.

[0106] When the low dielectric layer has heat fusibility, the low dielectric layer material may be melted to fuse the antenna circuit board and the first glass through the low dielectric layer material. Or, when a solution in which the low dielectric layer material is dissolved in a solvent has adhesiveness, the low dielectric layer material solution may be applied to the bonding surfaces of the first glass and / or the antenna circuit board, and the antenna circuit board and the first glass may be adhered through the low dielectric layer material. In addition, from the viewpoint of preventing air from being mixed during fusion or adhesion (hereinafter referred to as fusion, etc.), it is preferably performed under degassing and / or reduced pressure. Degassing may be performed by physically extruding air from the bonding interface. For fusion, etc., after positioning the antenna circuit board by preliminarily performing fusion, etc., the antenna circuit board and the first glass may be fused, etc. under degassing and / or reduced pressure.

[0107] Examples of the adhesive low dielectric layer include polyvinyl acetal resin, olefin-vinyl carboxylate copolymer resin, ionomer resin, acrylic resin, etc., which have good affinity for glass materials. When the adhesive low dielectric layer can be adhered by heat pressing, disconnection and deformation of the circuit during the adhesion can be suppressed, and even when the glass substrate is a curved glass such as an automotive front glass, foaming and peeling can be suppressed following it. Furthermore, when forming an antenna system as laminated glass in which a high-frequency antenna circuit board is embedded between glass substrates, lamination under general production conditions of the laminated glass is possible, so extra processes can be omitted.

[0108] (Polyvinyl acetal resin) Examples of the polyvinyl acetal resin include those produced by acetalizing a vinyl alcohol-based resin such as polyvinyl alcohol or a vinyl alcohol copolymer. When the low dielectric layer contains a polyvinyl acetal resin, it may contain one type of polyvinyl acetal resin, or it may contain two or more polyvinyl acetal resins that differ from each other in any one or more of the viscosity average degree of polymerization, degree of acetalization, amount of acetyl groups, amount of hydroxyl groups, ethylene content, molecular weight of the aldehyde used for acetalization, and chain length. When the polyvinyl acetal resin contains two or more different polyvinyl acetal resins, it is preferably a mixture of two or more polyvinyl acetal resins that differ from each other in any one or more of the viscosity average degree of polymerization, degree of acetalization, amount of acetyl groups, and amount of hydroxyl groups, from the viewpoint of ease of melt molding and the like.

[0109] The polyvinyl acetal resin used in the present invention can be obtained by known or conventional methods. For example, an aldehyde (or ketone compound) and an acid catalyst are added to an aqueous solution of polyvinyl alcohol or a vinyl alcohol copolymer to carry out an acetalization reaction. Then, after filtering the reaction solution as necessary, a neutralizing agent such as an alkali is added for neutralization, and the resin is filtered, washed with water, and dried to obtain a polyvinyl acetal resin.

[0110] Polyvinyl alcohol can be obtained by saponifying a polyvinyl ester obtained by polymerizing a vinyl ester compound, and a vinyl alcohol copolymer can be obtained by saponifying a copolymer of a vinyl ester compound and another monomer.

[0111] Examples of vinyl ester compounds include vinyl aliphatic carboxylates such as vinyl acetate, 1-propenyl acetate, 1-methylvinyl acetate, 1-butenyl acetate, 2-methyl-1-propenyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versatate, vinyl pentanoate, vinyl hexanoate, vinyl octanoate, vinyl decanoate, vinyl dodecanoate, vinyl hexadecanoate, vinyl octadecanoate, and vinyl aromatic carboxylates such as vinyl benzoate. These vinyl ester compounds can be used alone or in combination. Among these vinyl ester compounds, vinyl acetate is preferred from the viewpoint of productivity.

[0112] Examples of other monomers include α-olefins such as ethylene, propylene, n-butene, and isobutylene; acrylic acid and its salts; acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate; methacrylic acid and its salts; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate; acrylamide; acrylamide derivatives such as N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetone acrylamide, acrylamide propanesulfonic acid and its salts, acrylamide propyl dimethylamine and its salts or its quaternary salts, and N-methylolacrylamide and its derivatives; methacrylamide; methacrylamide derivatives such as N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamide propanesulfonic acid and its salts, methacrylamide propyl dimethylamine and its salts or its quaternary salts, and N-methylolmethacrylamide and its derivatives; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene halides such as vinylidene chloride and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid and their salts, esters, or anhydrides; vinylsilyl compounds such as vinyltrimethoxysilane, etc. These other monomers can be used alone or in combination of two or more. Among them, ethylene is preferred as the other monomer.

[0113] The acid catalyst used in the acetalization reaction is not particularly limited, and any of organic acids and inorganic acids can be used. Examples thereof include acetic acid, p-toluenesulfonic acid, nitric acid, sulfuric acid, hydrochloric acid and the like. Among them, hydrochloric acid, sulfuric acid and nitric acid are preferable from the viewpoints of the acid strength and the ease of removal during washing.

[0114] The aldehyde (or ketone compound) used in the production of the polyvinyl acetal resin preferably has a linear, branched or cyclic structure having 1 to 10 carbon atoms, and more preferably has a linear or branched structure. Thereby, a corresponding linear or branched acetal side chain is brought about. Further, the polyvinyl acetal resin used in the present invention may be obtained by acetalizing polyvinyl alcohol or a vinyl alcohol copolymer with a mixture of a plurality of aldehydes (or ketone compounds). The polyvinyl alcohol or vinyl alcohol copolymer may be composed of only one of them, or may be a mixture of polyvinyl alcohol and a vinyl alcohol copolymer.

[0115] Examples of the aldehyde include aliphatic, aromatic, and alicyclic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, n-butylaldehyde, isobutylaldehyde, valeraldehyde, isovaleraldehyde, n-hexylaldehyde, 2-ethylbutylaldehyde, n-heptylaldehyde, n-octylaldehyde, 2-ethylhexylaldehyde, n-nonylaldehyde, n-decylaldehyde, benzaldehyde, and cinnamaldehyde. Among them, aliphatic unbranched aldehydes having 2 to 6 carbon atoms are preferable, and n-butylaldehyde is particularly preferable from the viewpoint of easily obtaining a polyvinyl acetal resin having suitable breaking energy. These aldehydes can be used alone or in combination of two or more. Further, polyfunctional aldehydes and aldehydes having other functional groups may be used in combination within the range of 20% by mass or less of the total aldehydes. When using n-butylaldehyde, the content of n-butylaldehyde in the aldehyde used for acetalization is preferably 50% by mass or more, more preferably 80% by mass or more, further preferably 95% by mass or more, particularly preferably 99% by mass or more, and may be 100% by mass.

[0116] The viscosity average degree of polymerization of polyvinyl alcohol as a raw material of the polyvinyl acetal resin is preferably 100 or more, more preferably 300 or more, further preferably 400 or more, still more preferably 600 or more, particularly preferably 700 or more, and most preferably 750 or more. When using a polyvinyl acetal resin composition containing a large amount of a plasticizer (for example, 20 parts by mass or more), the viscosity average degree of polymerization of polyvinyl alcohol as a raw material of the polyvinyl acetal resin is preferably 500 or more, more preferably 900 or more, further preferably 1000 or more, still more preferably 1200 or more, particularly preferably 1500 or more, and most preferably 1600 or more. Also, the viscosity average degree of polymerization of polyvinyl alcohol is preferably 5000 or less, more preferably 3000 or less, further preferably 2500 or less, particularly preferably 2300 or less, and most preferably 2000 or less. The viscosity-average degree of polymerization of polyvinyl alcohol can be measured, for example, based on JIS K 6726, "Test Methods for Polyvinyl Alcohol."

[0117] Generally, since the viscosity-average degree of polymerization of the polyvinyl acetal resin coincides with that of the polyvinyl alcohol used as a raw material, the preferred viscosity-average degree of polymerization of the above-mentioned polyvinyl alcohol coincides with that of the polyvinyl acetal resin. When the low dielectric layer contains two or more different polyvinyl acetal resins, it is preferable that the viscosity-average degree of polymerization of at least one polyvinyl acetal resin is not less than the lower limit value and not more than the upper limit value.

[0118] The amount of acetyl groups in the polyvinyl acetal resin constituting the low dielectric layer is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, and still more preferably 0.1 to 5% by mass, based on the ethylene units of the polyvinyl acetal main chain. The amount of acetyl groups in the polyvinyl acetal resin can be adjusted by appropriately adjusting the saponification degree of the raw material polyvinyl alcohol or vinyl alcohol copolymer. When the low dielectric layer contains two or more different polyvinyl acetal resins, it is preferable that the amount of acetyl groups in at least one polyvinyl acetal resin is within the above range.

[0119] The degree of acetalization of the polyvinyl acetal resin used in the present invention is not particularly limited, but is preferably 40 to 86 mol%, more preferably 45 to 82 mol%, still more preferably 50 to 78 mol%, particularly preferably 60 to 74 mol%, and most preferably 68 to 74 mol%. By appropriately adjusting the amount of aldehyde used when acetalizing the polyvinyl alcohol resin, the degree of acetalization of the polyvinyl acetal resin can be adjusted within the above range. When the degree of acetalization is within the above range, the compatibility between the polyvinyl acetal resin and the plasticizer is less likely to decrease. When the low dielectric layer contains two or more different polyvinyl acetal resins, it is preferable that the degree of acetalization of at least one polyvinyl acetal resin is within the above range.

[0120] The amount of hydroxyl groups in the polyvinyl acetal resin is preferably 6 to 26% by mass, more preferably 12 to 24% by mass, still more preferably 15 to 22% by mass, and particularly preferably 18 to 21% by mass, based on the ethylene units in the polyvinyl acetal main chain. By adjusting the amount of aldehyde used when acetalizing the polyvinyl alcohol resin, the amount of hydroxyl groups can be adjusted within the above range. When the low dielectric layer contains two or more polyvinyl acetal resins with different properties, it is preferable that the amount of hydroxyl groups in at least one polyvinyl acetal resin is within the above range.

[0121] The polyvinyl acetal resin is usually composed of acetal group units, hydroxyl group units and acetyl group units, and the amount of each of these units can be measured by, for example, JIS K 6728 "Test Methods for Polyvinyl Butyral" or nuclear magnetic resonance method (NMR). When the polyvinyl acetal resin contains units other than acetal group units, the unit amount of hydroxyl groups and the unit amount of acetyl groups are measured, and the remaining amount of acetal group units can be calculated by subtracting the sum of these two unit amounts from the amount of acetal group units when no units other than acetal group units are included.

[0122] From the viewpoint of easily obtaining good film-forming properties, the low dielectric layer preferably contains uncrosslinked polyvinyl acetal, but it is also possible to contain crosslinked polyvinyl acetal. For example, as a method of crosslinking, the polyvinyl acetal may be crosslinked by thermal self-crosslinking with a carboxyl group-containing polyvinyl acetal, intermolecular crosslinking with a polyaldehyde, glyoxylic acid, or the like.

[0123] The viscosity of the polyvinyl acetal resin can be appropriately set according to the type used. For example, when forming a thin low dielectric layer, the viscosity of a toluene / ethanol = 1 / 1 (mass ratio) solution with a concentration of 10% by mass, measured at 20 °C and 30 rpm using a Brookfield type (B-type) viscometer, may be 100 to 1000 mPa·s, preferably 120 to 800 mPa·s, more preferably 150 to 600 mPa·s, still more preferably 180 to 500 mPa·s, and particularly preferably 200 to 400 mPa·s. By using a polyvinyl acetal resin having a viscosity within the above range, when heat-pressing and adhering to a glass substrate, it is easy to set the heating temperature or heating time within a desired range, and it is possible to reduce the remaining unmelted portion of the polyvinyl acetal resin. In addition, even when the antenna system is exposed to a high temperature, it is possible to suppress the displacement of the arrangement of the antenna circuit board. The viscosity of the polyvinyl acetal resin can be adjusted by using, alone or in combination, a polyvinyl alcohol-based resin having a high or low viscosity average degree of polymerization as a raw material or a part of the raw material. When the polyvinyl acetal resin used to form the low dielectric layer is composed of a mixture of a plurality of resins, the viscosity is the viscosity of such a mixture.

[0124] Furthermore, the polyvinyl acetal resin may be combined with a known or conventional plasticizer as necessary. Examples of the plasticizer include the following plasticizers. These plasticizers may be used alone or in combination of two or more. For example, a plasticized polyvinyl acetal resin composition composed of a plasticizer and a polyvinyl acetal resin may form a low dielectric layer.

[0125] As the plasticizer, for example, the following can be used. · Esters of polyvalent aliphatic or aromatic acids. For example, dialkyl adipates (e.g., dihexyl adipate, di-2-ethylbutyl adipate, dioctyl adipate, di-2-ethylhexyl adipate, hexyl cyclohexyl adipate, a mixture of heptyl adipate and nonyl adipate, diisononyl adipate, heptyl nonyl adipate); esters of adipic acid with an alicyclic ester alcohol or an alcohol containing an ether compound (e.g., di(butoxyethyl) adipate, di(butoxyethoxyethyl) adipate); dialkyl sebacates (e.g., dibutyl sebacate); esters of sebacic acid with an alcohol containing an alicyclic or ether compound; esters of phthalic acid (e.g., butyl benzyl phthalate, bis-2-butoxyethyl phthalate); and esters of alicyclic polyvalent carboxylic acids with aliphatic alcohols (e.g., diisononyl 1,2-cyclohexanedicarboxylate). · Esters or ethers of polyvalent aliphatic or aromatic alcohols or oligoether glycols having one or more aliphatic or aromatic substituents. For example, esters of glycerin, diglycol, triglycol, tetra glycol, etc. with linear or branched aliphatic or alicyclic carboxylic acids can be mentioned. Specifically, diethylene glycol-bis-(2-ethylhexanoate), triethylene glycol-bis-(2-ethylhexanoate), triethylene glycol-bis-(2-ethylbutanoate), tetraethylene glycol-bis-n-heptanoate, triethylene glycol-bis-n-heptanoate, triethylene glycol-bis-n-hexanoate, tetraethylene glycol dimethyl ether, and dipropylene glycol benzoate can be mentioned. · Phosphoric acid esters of aliphatic or aromatic ester alcohols. For example, tris(2-ethylhexyl) phosphate (TOF), triethyl phosphate, diphenyl-2-ethylhexyl phosphate, and tricresyl phosphate can be mentioned. · Esters of citric acid, succinic acid and / or fumaric acid.

[0126] Alternatively, a polyester or oligoester composed of a polyhydric alcohol and a polycarboxylic acid, a terminal esterified product or etherified product thereof, a polyester or oligoester composed of a lactone or a hydroxycarboxylic acid, or a terminal esterified product or etherified product thereof, etc. may be used as a plasticizer.

[0127] The content of the plasticizer may be, for example, 0 to 40% by mass, preferably 0 to 30% by mass, more preferably 0 to 15% by mass, still more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass with respect to the total amount of the polyvinyl acetal resin and the plasticizer. Preferred polyvinyl acetal resins are, for example, marketed as "Movital (trademark)" by Kuraray Co., Ltd., and polyvinyl acetal resin films are, for example, marketed as "Trosifol (trademark)" by Kuraray Co., Ltd.

[0128] Alternatively, when adhering a low dielectric layer composed of a polyvinyl acetal resin to an adherend, a plasticizer may be further applied to a film or the like composed of a polyvinyl acetal resin to enhance the adhesiveness of the polyvinyl acetal resin with the plasticizer. As such a plasticizer, the above-described plasticizers can be used, and since the adhesiveness of the low dielectric layer can be improved, triethylene glycol-bis-(2-ethylbutanoate), triethylene glycol-bis-(2-ethylhexanoate), dihexyl adipate, dibutyl sebacate, di(butoxyethyl) adipate, and di(butoxyethoxyethyl) adipate are preferred, triethylene glycol-bis-(2-ethylhexanoate), di(butoxyethyl) adipate, and di(butoxyethoxyethyl) adipate are more preferred, and di(butoxyethyl) adipate and di(butoxyethoxyethyl) adipate are particularly preferred.

[0129] (Olefin-vinyl carboxylate copolymer resin) The olefin-vinyl carboxylate copolymer resin is not particularly limited as long as it has a dielectric constant lower than that of the first glass layer. Examples of the olefin include ethylene, propylene, n-butene, isobutylene, butadiene, isoprene, etc. Examples of the vinyl carboxylate include the vinyl ester compounds exemplified in the section on polyvinyl acetal resins. Among these, an ethylene-vinyl acetate copolymer resin using ethylene as the olefin and vinyl acetate as the vinyl carboxylate compound is preferable because it can control the dielectric constant and has good adhesiveness.

[0130] The olefin-vinyl carboxylate copolymer resin may further copolymerize a monomer as a third component as long as the dielectric constant can be controlled within a predetermined range. Examples of the monomer as the third component include acrylic esters, methacrylic esters, acrylamide and its derivatives, methacrylamide and its derivatives, vinyl ethers, nitriles, vinyl halides, vinylidene halides, allyl compounds, unsaturated carboxylic acids and their derivatives, vinyl silyl compounds, etc. described in the section on polyvinyl acetal resins. These monomers can be used alone or in combination of two or more. When copolymerizing these other monomers, usually, these other monomers are preferably used in a proportion of less than 10 mol% based on the vinyl carboxylate compound.

[0131] In the olefin-vinyl carboxylate copolymer resin, from the viewpoint of strength, the ratio of the vinyl carboxylate unit to the total of the olefin unit and the vinyl carboxylate unit is preferably, for example, less than 50 mol%, more preferably 30 mol% or less, still more preferably 20 mol% or less, and particularly preferably 15 mol% or less. The lower limit value of the vinyl carboxylate is not particularly limited, but may be, for example, about 5 mol%. Preferred olefin-vinyl carboxylate copolymer resins are, for example, marketed as "Melsen (trademark)" etc. by Tosoh Corporation as ethylene vinyl acetate.

[0132] (Ionomer resin) The ionomer resin is not particularly limited, and examples thereof include thermoplastic resins having structural units derived from olefins such as ethylene and structural units derived from α,β-unsaturated carboxylic acids, with at least a part of the α,β-unsaturated carboxylic acids neutralized by metal ions. Examples of the metal ions include alkali metal ions such as sodium ions; alkaline earth metal ions such as magnesium ions; zinc ions and the like.

[0133] In the ethylene-α,β-unsaturated carboxylic acid copolymer before being neutralized by metal ions, the content of the structural unit of the α,β-unsaturated carboxylic acid is preferably 2% by mass or more, more preferably 5% by mass or more, based on the mass of the ethylene-α,β-unsaturated carboxylic acid copolymer. Also, the content of the structural unit of the α,β-unsaturated carboxylic acid is preferably 30% by mass or less, more preferably 20% by mass or less.

[0134] Examples of the structural unit derived from α,β-unsaturated carboxylic acid that the ionomer resin has include structural units derived from acrylic acid, methacrylic acid, maleic acid, monomethyl maleate, monoethyl maleate, maleic anhydride, etc. Among them, the structural unit derived from acrylic acid or methacrylic acid is particularly preferred.

[0135] From the viewpoint of easy availability, ionomers of ethylene-acrylic acid copolymers and ionomers of ethylene-methacrylic acid copolymers are more preferred as the above ionomer resin, and zinc ionomers of ethylene-acrylic acid copolymers, sodium ionomers of ethylene-acrylic acid copolymers, zinc ionomers of ethylene-methacrylic acid copolymers, and sodium ionomers of ethylene-methacrylic acid copolymers are particularly preferred. The ionomer resin can be used alone or in combination of two or more. Preferred films made of ionomer resin are, for example, marketed as "Centigrass (trademark)" by Kuraray Co., Ltd.

[0136] (Acrylic resin) The acrylic resin is preferably a polymer obtained from an acrylate monomer and / or a methacrylate monomer. Examples of the monomer include alkyl acrylates such as methyl acrylate, ethyl acrylate, and n-propyl acrylate; modified acrylates such as glycidyl acrylate and 2-hydroxyethyl acrylate; polyfunctional acrylates such as ethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, neopentyl glycol diacrylate, and pentaerythritol triacrylate; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, and n-propyl methacrylate; modified methacrylates such as glycidyl methacrylate and 2-hydroxyethyl methacrylate; and polyfunctional methacrylates such as ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, and pentaerythritol trimethacrylate. These monomers can be used alone or in combination of two or more.

[0137] In addition, a copolymer of an acrylate monomer and / or a methacrylate monomer with an unsaturated carboxylic acid such as acrylic acid and methacrylic acid; acrylamides such as N,N-dimethylacrylamide; and aromatic vinyl compounds such as styrene and α-methylstyrene can also be suitably used as the acrylic resin.

[0138] Preferred acrylic resins include liquid injection resins such as those marketed by Shin-Ko Glass Industries Co., Ltd. under the name "3S Resin".

[0139] The low dielectric layer may contain known or conventional additives as required. Examples of the additives include solvents, plasticizers, ultraviolet absorbers, antioxidants, adhesion modifiers, whitening agents or fluorescent brighteners, stabilizers, pigments, processing aids, organic or inorganic nanoparticles, fired silicic acid, and surfactants. The additives can be used alone or in combination of two or more.

[0140] (Antenna circuit board) The antenna circuit board includes at least one circuit layer and at least one high-frequency insulating layer, and its form is not particularly limited, and it can be used as various high-frequency circuit boards by known or conventional means.

[0141] The present invention also includes the antenna circuit board, and the antenna circuit board of the present invention can be usefully used in the antenna system of the present invention due to the high-frequency characteristics derived from the high-frequency insulating layer.

[0142] The circuit layer is formed of, for example, at least a metal having conductivity, and a circuit may be formed using a known circuit processing method. The conductor forming the circuit layer may be various metals having conductivity, such as gold, silver, copper, iron, nickel, aluminum, or alloy metals thereof.

[0143] In addition, the antenna circuit board may include a conductor layer such as a ground layer in addition to the circuit layer. The conductor layer may be composed of various metals having conductivity, such as gold, silver, copper, iron, nickel, aluminum, or alloy metals thereof. The conductors constituting the circuit layer and the conductor layer may be the same or different.

[0144] The antenna circuit board may be used for various transmission lines, such as known or conventional transmission lines such as coaxial lines, strip lines, microstrip lines, coplanar lines, and parallel lines, or may be used for an antenna (for example, an antenna for microwaves or millimeter waves). Further, the circuit board may be used for an antenna device in which an antenna and a transmission line are integrated.

[0145] As for the antenna structure, as long as a high-frequency insulating layer is used, it may have a known or conventional structure. For example, antennas that utilize millimeter waves and microwaves such as waveguide slot antennas, horn antennas, lens antennas, chip antennas, pattern antennas, printed antennas, triplate antennas, microstrip antennas, patch antennas, etc. may be mentioned. The antenna circuit board (or semiconductor element mounting board) may be used for various sensors, particularly in-vehicle radars.

[0146] The antenna circuit board may be a multilayer circuit board having a plurality of circuit layers and / or conductor layers. Further, the antenna circuit board may be a circuit board (or semiconductor element mounting board) on which a semiconductor element (for example, an IC chip) is mounted.

[0147] The high-frequency antenna circuit board may be capable of supporting a data transmission speed of 10 gigabits per second or more. For example, the high-frequency antenna circuit board may be a circuit board compatible with 5G and the next generation.

[0148] (High-frequency insulating layer) The antenna circuit board is provided with a high-frequency insulating layer. The high-frequency insulating layer is not particularly limited as long as it is an insulating layer capable of reducing the transmission loss of electrical signals in a high-frequency circuit. For example, insulating layers made of heat-resistant resins such as thermoplastic liquid crystal polymer (LCP), polyimide (PI) (particularly modified polyimide (MPI)), polyethylene naphthalate (PEN), polyether ether ketone (PEEK), etc. may be mentioned. Among them, an insulating layer made of polyimide is preferably adopted because it has excellent heat resistance and chemical resistance. Also, thermoplastic liquid crystal polymer is preferably adopted in terms of excellent dielectric properties.

[0149] For example, the insulating layer may be formed from a thermoplastic liquid crystal polymer film or a polyimide film. In that case, a circuit layer etc. may be disposed on the thermoplastic liquid crystal polymer film or the polyimide film to obtain an antenna circuit board.

[0150] The dielectric constant εp in both a unidirectional direction and the direction perpendicular thereto in the plane of the high-frequency insulating layer may be, for example, 2.0 to 4.0 at a frequency of 28 GHz, preferably 2.2 to 3.5, and more preferably 2.4 to 3.0. Also, the dielectric constant εf of the low dielectric layer and the dielectric constant εp of the high-frequency insulating layer may be εf / εp = 30 / 70 to 60 / 40, preferably 35 / 65 to 60 / 40, and more preferably 38 / 62 to 55 / 45.

[0151] The dielectric tangent tanδp in both a unidirectional direction and the direction perpendicular thereto in the plane of the high-frequency insulating layer may be, for example, 0.010 or less at a frequency of 28 GHz, preferably 0.005 or less, and more preferably 0.003 or less. Here, the dielectric properties are values measured by the method described above.

[0152] From the viewpoint of excellent heat resistance, an insulating layer made of polyimide (hereinafter sometimes referred to as a polyimide insulating layer) is preferable. Polyimide is not particularly limited as long as it is a polymer having an imide group in its structural unit, and examples thereof include polyimide-based resins such as polyimide, polyamideimide, polybenzimidazole, polyimide ester, polyetherimide, and polysiloxane imide.

[0153] Polyimide can be formed by imidizing (curing) a polyamic acid which is a precursor. The polyamic acid can be synthesized by reacting a known diamine and a tetracarboxylic acid (including its acid anhydride) in the presence of a solvent. As the diamine, aromatic diamines, aliphatic diamines, alicyclic diamines, etc. can be used, and from the viewpoint of heat resistance, aromatic diamines are preferred. Examples of the aromatic diamine include 4,4'-diaminodiphenyl ether, 2'-methoxy-4,4'-diaminobenzanilide, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 4,4'-diaminobenzanilide, 5-amino-2-(p-aminophenyl)benzoxazole, etc. Also, as the tetracarboxylic acid, aromatic tetracarboxylic acids, aliphatic tetracarboxylic acids, alicyclic tetracarboxylic acids, their acid anhydrides, etc. can be used, and from the viewpoint of heat resistance, aromatic tetracarboxylic acid anhydrides are preferred. Examples of the aromatic tetracarboxylic acid anhydride include pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, etc. These diamines and tetracarboxylic acids can be used alone or in combination of two or more.

[0154] The polyimide film used for the polyimide insulating layer can be manufactured, for example, by applying a solution of a polyamic acid (a polyimide precursor) obtained by reacting a diamine and a tetracarboxylic acid onto a support, drying to obtain a polyamic acid film, and then performing heat treatment to cure (imidize) it. For the application of the polyamic acid solution, known coating methods such as spin coating, comma coater, screen printing method, slit coating, roll coating, knife coating, dip coating, die coating, etc. can be used.

[0155] Various additives, fillers, etc. may be added to the polyimide film as long as the effects of the present invention are not impaired.

[0156] Examples of the polyimide film include those commercially available such as Kapton EN, Kapton H, Kapton V (all trade names) manufactured by Toray DuPont Co., Ltd., Apical NPI (trade name) manufactured by Kaneka Corporation, and Upilex S (trade name) manufactured by Ube Industries, Ltd.

[0157] From the viewpoint of excellent dielectric properties, an insulating layer composed of a thermoplastic liquid crystal polymer (hereinafter sometimes referred to as a thermoplastic liquid crystal polymer insulating layer) is preferable. The thermoplastic liquid crystal polymer film used for the thermoplastic liquid crystal polymer insulating layer is formed from a liquid crystalline polymer that can be melt-molded. This thermoplastic liquid crystal polymer is a polymer that can form an optically anisotropic molten phase, and its chemical composition is not particularly limited as long as it is a liquid crystalline polymer that can be melt-molded. Examples thereof include thermoplastic liquid crystal polyester or thermoplastic liquid crystal polyester amide in which an amide bond is introduced therein.

[0158] The thermoplastic liquid crystal polymer may also be a polymer in which an isocyanate-derived bond such as an imide bond, a carbonate bond, a carbodiimide bond, or an isocyanurate bond is further introduced into an aromatic polyester or an aromatic polyester amide.

[0159] Specific examples of the thermoplastic liquid crystal polymer used in the present invention include known thermoplastic liquid crystal polyesters and thermoplastic liquid crystal polyester amides derived from the compounds classified into (1) to (4) exemplified below and their derivatives. However, it goes without saying that there is an appropriate range for various combinations of raw material compounds in order to form a polymer that can form an optically anisotropic molten phase.

[0160] (1) Aromatic or aliphatic dihydroxy compounds (see Table 1 for representative examples)

Table 1

[0161] (2) Aromatic or aliphatic dicarboxylic acids (see Table 2 for representative examples)

Table 2

[0162] (3) Aromatic hydroxycarboxylic acids (see Table 3 for representative examples)

Table 3

[0163] (4) Aromatic diamines, aromatic hydroxyamines or aromatic aminocarboxylic acids (see Table 4 for representative examples)

Table 4

[0164] As representative examples of the thermoplastic liquid crystal polymers obtained from these raw material compounds, copolymers having the structural units shown in Tables 5 and 6 can be cited.

[0165]

Table 5

[0166]

Table 6

[0167] Among these copolymers, polymers containing p-hydroxybenzoic acid and / or 6-hydroxy-2-naphthoic acid as at least repeating units are preferred. In particular, (i) polymers containing repeating units of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, or (ii) copolymers containing repeating units of at least one aromatic hydroxycarboxylic acid selected from the group consisting of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, at least one aromatic diol and / or aromatic hydroxyamine, and at least one aromatic dicarboxylic acid are preferred.

[0168] For example, in the polymer of (i), when the thermoplastic liquid crystal polymer contains at least repeating units of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, the molar ratio (A) / (B) of p-hydroxybenzoic acid of repeating unit (A) to 6-hydroxy-2-naphthoic acid of repeating unit (B) is desirably about (A) / (B) = 10 / 90 to 90 / 10 in the thermoplastic liquid crystal polymer, more preferably, (A) / (B) may be about 15 / 85 to 85 / 15, and even more preferably, (A) / (B) may be about 20 / 80 to 80 / 20.

[0169] Also, in the case of the polymer of (ii), the molar ratio of each repeating unit in the thermoplastic liquid crystal polymer of at least one aromatic hydroxycarboxylic acid (C) selected from the group consisting of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, at least one aromatic diol (D) selected from the group consisting of 4,4'-dihydroxybiphenyl, hydroquinone, phenylhydroquinone, and 4,4'-dihydroxydiphenyl ether, and at least one aromatic dicarboxylic acid (E) selected from the group consisting of terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid may be about aromatic hydroxycarboxylic acid (C): said aromatic diol (D): said aromatic dicarboxylic acid (E) = (30 to 80):(35 to 10):(35 to 10), more preferably, (C):(D):(E) may be about (35 to 75):(32.5 to 12.5):(32.5 to 12.5), and even more preferably, (C):(D):(E) may be about (40 to 70):(30 to 15):(30 to 15).

[0170] Also, the molar ratio of the repeating unit derived from 6-hydroxy-2-naphthoic acid among the aromatic hydroxycarboxylic acids (C) may be, for example, 85 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more. The molar ratio of the repeating unit derived from 2,6-naphthalenedicarboxylic acid among the aromatic dicarboxylic acids (E) may be, for example, 85 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more.

[0171] Also, the aromatic diol (D) may be repeating units (D1) and (D2) derived from two different aromatic diols selected from the group consisting of hydroquinone, 4,4'-dihydroxybiphenyl, phenylhydroquinone, and 4,4'-dihydroxydiphenyl ether. In that case, the molar ratio of the two aromatic diols may be (D1) / (D2) = 23 / 77 to 77 / 23, more preferably 25 / 75 to 75 / 25, and even more preferably 30 / 70 to 70 / 30.

[0172] In addition, the molar ratio of the repeating structural unit derived from the aromatic diol to the repeating structural unit derived from the aromatic dicarboxylic acid is preferably (D) / (E)=95 / 100 to 100 / 95. If it is out of this range, the degree of polymerization does not increase and the mechanical strength tends to decrease.

[0173] Note that the ability to form an optically anisotropic molten phase as referred to in the present invention can be determined, for example, by placing a sample on a hot stage, heating it while raising the temperature under a nitrogen atmosphere, and observing the transmitted light of the sample.

[0174] Preferred thermoplastic liquid crystal polymers may have a melting point (hereinafter referred to as Tm0) in the range of 200 to 360 °C, preferably in the range of 240 to 360 °C, more preferably in the range of 260 to 360 °C, and even more preferably Tm0 is in the range of 270 to 350 °C. Note that Tm0 is determined by measuring the temperature at which the main endothermic peak appears using a differential scanning calorimeter (DSC, Shimadzu Corporation). That is, after heating a thermoplastic liquid crystal polymer sample at a rate of 10 °C / min to completely melt it, the melt is cooled to 50 °C at a rate of 10 °C / min, and then heated again at a rate of 10 °C / min. The position of the endothermic peak that appears is determined as the melting point of the thermoplastic liquid crystal polymer sample.

[0175] In the thermoplastic liquid crystal polymer, within a range that does not impair the effects of the present invention, thermoplastic polymers such as polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyarylate, polyamide, polyphenylene sulfide, polyether ether ketone, fluororesin, various additives, fillers, etc. may be added.

[0176] The thermoplastic liquid crystal polymer film is obtained, for example, by extruding a melt-kneaded product of the thermoplastic liquid crystal polymer. Any extrusion method can be used, but well-known T-die methods, inflation methods, etc. are industrially advantageous. In particular, in the inflation method, stress is applied not only in the machine axis direction (hereinafter abbreviated as the MD direction) of the thermoplastic liquid crystal polymer film but also in the direction orthogonal thereto (hereinafter abbreviated as the TD direction), and since uniform stretching can be performed in the MD direction and the TD direction, a thermoplastic liquid crystal polymer film with controlled molecular orientation, dielectric properties, etc. in the MD direction and the TD direction can be obtained.

[0177] Also, if necessary, known or conventional heat treatment may be performed to adjust the melting point and / or coefficient of thermal expansion of the thermoplastic liquid crystal polymer film. The heat treatment conditions can be appropriately set according to the purpose. For example, by heating for several hours at a temperature of 10 °C or more above the melting point (Tm0) of the thermoplastic liquid crystal polymer (for example, about Tm0 - 10 °C to Tm0 + 30 °C, preferably about Tm0 °C to Tm0 + 20 °C), the melting point (Tm) of the thermoplastic liquid crystal polymer film may be increased.

[0178] It is possible to fabricate an antenna circuit board having a thermoplastic liquid crystal polymer insulating layer by providing a circuit layer and / or a conductor layer on the obtained thermoplastic liquid crystal polymer film by a known or conventional method.

[0179] The melting point (Tm) of the thermoplastic liquid crystal polymer insulating layer may be, for example, 200 to 380 °C, and preferably in the range of 240 to 370 °C. The melting point (Tm) of the thermoplastic liquid crystal polymer insulating layer can be obtained by observing the thermal behavior of a sample obtained from the thermoplastic liquid crystal polymer insulating layer (or the thermoplastic liquid crystal polymer film) using a differential scanning calorimeter. That is, the position of the endothermic peak that appears when the thermoplastic liquid crystal polymer film sample is heated at a rate of 10 °C / min can be determined as the melting point (Tm) of the thermoplastic liquid crystal polymer film.

[0180] The thermoplastic liquid crystal polymer insulating layer has, for example, a coefficient of thermal expansion of 0 to 25 ppm / °C, and the coefficient of thermal expansion may preferably be about 5 to 22 ppm / °C. Note that the coefficient of thermal expansion can be determined as the value measured between 30°C and 150°C when the temperature is raised from 25°C to 200°C at a rate of 5°C / min using a thermomechanical analyzer (TMA), then cooled to 30°C at a rate of 20°C / min, and then the temperature is raised again at a rate of 5°C / min.

Examples

[0181] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

[0182] [Dielectric Constant and Dielectric Loss Tangent] Regarding the films used in the following low dielectric layer and high frequency insulating layer, the dielectric constant and dielectric loss tangent were measured at a frequency of 28 GHz (25°C) in accordance with JIS R 1660-2 using Model No. DPS03 (Fabry-Perot resonator) manufactured by Keycom Co., Ltd. The measurements were carried out in both the one-way direction and the direction perpendicular thereto (X-Y direction) on the plane.

[0183] [Antenna Circuit Board, Thickness of Low Dielectric Layer] The thickness of the antenna circuit board was measured using a micrometer (manufactured by Mitutoyo Corporation, model 227-201-CLM-15QM). The thickness of the low dielectric layer was measured using the film used as the low dielectric layer. Note that the thickness of the entire antenna system, as well as the thickness of the antenna circuit board and glass in the antenna system, may be measured respectively, and the thickness of the low dielectric layer may be obtained by subtracting the thickness of the antenna circuit board and glass from the thickness of the entire antenna system.

[0184] [Solution Viscosity of Polyvinyl Acetal Resin] The polyvinyl acetal resin constituting the polyvinyl acetal resin film was dissolved in a mixed solvent of toluene / ethanol = 1 / 1 (mass ratio) to a concentration of 10% by mass to prepare a solution. The viscosity of this solution was measured at 20 °C and a rotation speed of 30 rpm using a Brookfield type (B-type) viscometer.

[0185] [Example 1] <Fabrication of Antenna Circuit Board> Copper foils (electrolytic copper foil "H9A" manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., thickness 12 μm) were laminated on both sides of a thermoplastic liquid crystal polymer film (manufactured by Kuraray Co., Ltd., Vectra (registered trademark), thickness 50 μm, dielectric constant in the X direction: 3.4, dielectric constant in the Y direction: 3.4, dielectric tangent in the X direction: 0.002, dielectric tangent in the Y direction: 0.002). Using a vacuum hot press apparatus, the heating plate was set to 290 °C, and under a pressure of 4 MPa, it was pressure-bonded for 15 minutes to fabricate a copper-clad laminate having a structure of copper foil / thermoplastic liquid crystal polymer film / copper foil. By removing a part of the copper foil on one surface of the obtained copper-clad laminate with an etching solution to form a circuit, and repeating this operation, an antenna circuit board (5 cm in length, 5 cm in width) with a thickness of 400 μm was fabricated.

[0186] <Fabrication of Polyvinyl Acetal Resin Film> Polyvinyl butyral resin 1 (hydroxyl group content 19.8% by mass, acetalization degree 70.8 mol%, acetyl group content 1.0% by mass, resin viscosity 152 mPa·s) and polyvinyl butyral resin 2 (hydroxyl group content 20.1% by mass, acetalization degree 70.4 mol%, acetyl group content 0.9% by mass, resin viscosity 1410 mPa·s) were blended at a mass ratio of 75:25, melt-kneaded, extruded into strands, and pelletized. The obtained pellets were melt-extruded using a single-screw extruder and a T-die, and a polyvinyl acetal resin film (dielectric constant in the X direction: 2.5, dielectric constant in the Y direction: 2.5, dielectric tangent in the X direction: 0.01, dielectric tangent in the Y direction: 0.01, plasticizer content: 0% by mass, resin viscosity: 245 mPa·s) with a smooth surface and a thickness of 50 μm was obtained using a metal elastic roll.

[0187] <Fabrication of Laminate> On a lower glass with a length of 20 cm, a width of 10 cm, and a thickness of 3 mm, a Teflon (registered trademark) sheet with one-sided embossing, a dried polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm prepared above, an antenna circuit board (5 cm in length and 5 cm in width) prepared above, a Teflon (registered trademark) sheet with one-sided embossing, and an upper glass with a length of 5 cm, a width of 5 cm, and a thickness of 3 mm were stacked and fixed in this order. The polyvinyl acetal resin film, the antenna circuit board, and the upper glass were aligned so as to overlap each other. The Teflon (registered trademark) sheet adjacent to the polyvinyl acetal resin film was arranged such that the embossed surface was in contact with the polyvinyl acetal resin film. The Teflon (registered trademark) sheet adjacent to the antenna circuit board was arranged such that the mirror surface was in contact with the antenna circuit board. The antenna circuit board was arranged such that the surface having the circuit was in contact with the polyvinyl acetal resin film. These were heated in a vacuum laminator at 140 °C for 15 minutes under vacuum, then the upper chamber was set to -10 kPa (the differential pressure from the lower chamber was about 90 kPa) and held for 15 minutes, and then returned to normal pressure. The Teflon (registered trademark) sheets and the upper and lower glasses arranged above and below were removed to produce a laminate laminated in the order of polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer).

[0188] <Fabrication of Antenna System> On a lower glass with a length of 20 cm, a width of 10 cm, a thickness of 3 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01, the above laminate (5 cm in length and 5 cm in width) was overlapped such that the polyvinyl acetal resin film (low dielectric layer) was in contact with the lower glass, and a Teflon (registered trademark) sheet and an upper glass with a length of 5 cm, a width of 5 cm, and a thickness of 3 mm were overlapped and fixed in this order thereon. The antenna circuit board was disposed in a region 2 cm or more and 7 cm or less inward from the longitudinal end of the lower glass. Also, the laminate and the upper glass were aligned so as to overlap each other. These were heated at 140°C for 15 minutes under vacuum using a vacuum laminator. After that, the upper chamber was set to -10 kPa (the differential pressure with the lower chamber was approximately 90 kPa) and held for 15 minutes, and then returned to normal pressure. The Teflon (registered trademark) sheet and the upper glass were removed, and an antenna system was obtained in which a glass (first glass layer) / polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of the antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as the insulating layer) / copper foil (conductor layer) were laminated in this order, and the antenna circuit board was disposed on a part of the glass. In the obtained antenna system, no partial peeling or foaming was observed, and no disconnection or deformation of the circuit was observed either. Further, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of the glass, the high frequency incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0189] [Example 2] [Fabrication of Antenna System] On a lower glass with a length of 20 cm, a width of 10 cm, a thickness of 3 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01, the laminate (5 cm in length, 5 cm in width) obtained in Example 1 was overlapped so that the polyvinyl acetal resin film (low dielectric layer) was in contact with the lower glass. On top of that, a dried polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm and a thin plate glass with a length of 5 cm, a width of 5 cm, and a thickness of 1 mm were overlapped and fixed in this order. The antenna circuit board was disposed in a region 2 cm or more and 7 cm or less inward from the longitudinal end of the lower glass. Also, the laminate and the thin plate glass were aligned so as to overlap each other. These were heated in a vacuum laminator under vacuum at 140 °C for 15 minutes, then the upper chamber was set to -10 kPa (differential pressure from the lower chamber: approximately 90 kPa) and held for 15 minutes, and then returned to normal pressure. A glass (first glass layer) / polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer board with a thermoplastic liquid crystal polymer film as the insulating layer) / copper foil (conductor layer) / polyvinyl acetal resin film (low dielectric layer) / thin plate glass (protective layer) were laminated in this order, and an antenna system was obtained in which an antenna circuit board with a protective glass plate was disposed on a part of the glass. No partial peeling or foaming was observed in the obtained antenna system, and no disconnection or deformation of the circuit was observed either. Further, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of the glass, the high frequency incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0190] [Example 3] <Fabrication of laminate> On a glass with a length of 20 cm, a width of 10 cm, and a thickness of 3 mm, a Teflon (registered trademark) sheet with one-sided embossing, a dried polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm fabricated in Example 1, an antenna circuit board (length: 5 cm, width: 5 cm) fabricated in Example 1, a dried polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm fabricated in Example 1, and a thin plate glass with a length of 5 cm, a width of 5 cm, and a thickness of 1 mm were stacked and fixed in this order. The polyvinyl acetal resin film, the antenna circuit board, and the thin plate glass were aligned so as to overlap each other. The Teflon (registered trademark) sheet was arranged such that the embossed surface was in contact with the polyvinyl acetal resin film. The antenna circuit board was arranged such that the surface having the circuit was in contact with the polyvinyl acetal resin film adjacent to the Teflon (registered trademark) sheet. These were heated in a vacuum laminator at 140°C for 15 minutes under vacuum. After that, the upper chamber was set to -10 kPa (pressure difference from the lower chamber of about 90 kPa) and held for 15 minutes, then returned to normal pressure. The Teflon (registered trademark) sheet and the glass were removed, and a laminate laminated in the order of polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer board with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / polyvinyl acetal resin film (low dielectric layer) / thin plate glass (protective layer) was produced.

[0191] <Fabrication of Antenna System> On a glass with a length of 20 cm, a width of 10 cm, a thickness of 3 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01, the above laminate (5 cm in length and 5 cm in width) was overlapped and fixed so that the polyvinyl acetal resin film (low dielectric layer) was in contact with the glass. The laminate was disposed in a region 2 cm or more and 7 cm or less inward from the longitudinal end of the glass in the glass. These were heated in a vacuum laminator at 140°C for 15 minutes under vacuum. After that, the upper chamber was set to -10 kPa (pressure difference from the lower chamber of about 90 kPa) and held for 15 minutes, then returned to normal pressure. An antenna system was obtained in which a glass (first glass layer) / polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer board with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / polyvinyl acetal resin film (low dielectric layer) / thin plate glass (protective layer) were laminated in this order, and an antenna circuit board with a protective glass plate was disposed in a part of the glass. No partial peeling or foaming was observed in the obtained antenna system, and no disconnection or deformation of the circuit was observed either. Also, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of the glass, the high-frequency wave incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0192] [Example 4] <Fabrication of Laminate> On the lower glass with a length of 20 cm, a width of 10 cm, and a thickness of 3 mm, a Teflon (registered trademark) sheet with one-sided embossing, a dried polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm prepared in Example 1, an antenna circuit board (5 cm long and 5 cm wide) prepared in Example 1, a dried polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm prepared in Example 1, a Teflon (registered trademark) sheet with one-sided embossing, and an upper glass with a length of 5 cm, a width of 5 cm, and a thickness of 3 mm were stacked and fixed in this order. The Teflon (registered trademark) sheet was arranged so that the embossed surface was in contact with the polyvinyl acetal resin film. The antenna circuit board was arranged so that the surface having the circuit was in contact with the polyvinyl acetal resin film on the lower glass side. These were heated in a vacuum laminator at 140 °C for 15 minutes under vacuum, then the upper chamber was set to -10 kPa (the differential pressure from the lower chamber was about 90 kPa) and held for 15 minutes, and then returned to normal pressure. The Teflon (registered trademark) sheets arranged above and below and the upper and lower glasses were removed, and a laminate laminated in the order of polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / polyvinyl acetal resin film (low dielectric layer) was produced.

[0193] <Fabrication of Antenna System> On the glass with a length of 20 cm, a width of 10 cm, a thickness of 3 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01, the above laminate (5 cm long and 5 cm wide) was overlapped so that the polyvinyl acetal resin film (low dielectric layer) adjacent to the circuit layer was in contact with the glass, and a thin plate glass with a length of 5 cm, a width of 5 cm, and a thickness of 1 mm was overlapped and fixed thereon. The antenna circuit board was arranged in a region 2 cm or more and 7 cm or less inward from the longitudinal end of the glass. Also, the laminate and the thin plate glass were aligned so as to overlap each other. These were heated in a vacuum laminator under vacuum at 140°C for 15 minutes, then the upper chamber was set to -10 kPa (pressure difference from the lower chamber of about 90 kPa) and held for 15 minutes, and then returned to normal pressure. A glass (first glass layer) / polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer board with a thermoplastic liquid crystal polymer film as the insulating layer) / copper foil (conductor layer) / polyvinyl acetal resin film (low dielectric layer) / thin plate glass (protective layer) were laminated in this order, and an antenna system in which an antenna circuit board with a protective glass plate was disposed on a part of the glass was obtained. No partial peeling or foaming was observed in the obtained antenna system, and no disconnection or deformation of the circuit was observed either. Also, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of the glass, the high-frequency wave incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0194] [Example 5] <Fabrication of laminate> Instead of the polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm, a plasticized polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 0.38 mm, containing 72% by mass of polyvinyl butyral resin (hydroxyl group content 28.8% by mass, viscosity average degree of polymerization 1700) and 28% by mass of triethylene glycol-bis-(2-ethylhexanoate) (dielectric constant in the X direction: 2.7, dielectric constant in the Y direction: 2.7, dielectric tangent in the X direction: 0.02, dielectric tangent in the Y direction: 0.02) was used. In the same manner as in Example 1, a laminate was fabricated in which a plasticized polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer board with a thermoplastic liquid crystal polymer film as the insulating layer) / copper foil (conductor layer) were laminated in this order.

[0195] <Fabrication of antenna system> An antenna system was obtained in the same manner as in Example 1, except that the above laminate was used instead of the laminate of Example 1, with the layers laminated in the order of glass (first glass layer) / plasticized polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer), and an antenna circuit board was disposed on a part of the glass. No partial peeling or foaming was observed in the obtained antenna system, nor was there any disconnection or deformation of the circuit. Also, in the obtained antenna system, since the low dielectric layer has a lower dielectric constant than glass, high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0196] [Example 6] <Fabrication of Antenna System> An antenna system was obtained in the same manner as in Example 2, except that the laminate of Example 5 was used instead of the laminate of Example 1, and a plasticized polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 0.38 mm used in Example 5 was used instead of the polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm. The layers were laminated in the order of glass (first glass layer) / plasticized polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / plasticized polyvinyl acetal resin film (low dielectric layer) / thin glass plate (protective layer), and an antenna circuit board with a protective glass plate was disposed on a part of the glass. No partial peeling or foaming was observed in the obtained antenna system, nor was there any disconnection or deformation of the circuit. Also, in the obtained antenna system, since the low dielectric layer has a lower dielectric constant than glass, high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0197] [Example 7] <Fabrication of Laminate> Instead of the polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm, an ionomer resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm (a film obtained by thinning SentryGlas (registered trademark) SG5000 manufactured by Kuraray Co., Ltd. by hot pressing, dielectric constant in the X direction: 2.2, dielectric constant in the Y direction: 2.2, dielectric tangent in the X direction: 0.002, dielectric tangent in the Y direction: 0.002) was used. In the same manner as in Example 1, a laminate was fabricated in the order of ionomer resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer).

[0198] <Fabrication of Antenna System> Instead of the laminate of Example 1, the above laminate was used. Instead of the polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm, an ionomer resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm (a film obtained by thinning SentryGlas (registered trademark) SG5000 manufactured by Kuraray Co., Ltd. by hot pressing) was used. In the same manner as in Example 2, a glass (first glass layer) / ionomer resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / ionomer resin film (low dielectric layer) / thin plate glass (protective layer) was laminated in this order, and an antenna system in which an antenna circuit board with a protective glass plate was disposed in a part of the glass was obtained. No partial peeling or foaming was observed in the obtained antenna system, and no disconnection or deformation of the circuit was observed either. Also, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of the glass, the high frequency incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0199] [Example 8] <Fabrication of Laminate> Instead of using a polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm, a laminate is produced in the order of polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as the insulating layer) / copper foil (conductor layer) in the same manner as in Example 1, except that a polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 30 μm is used.

[0200] <Fabrication of Antenna System> An antenna system is obtained in which a glass (first glass layer) / polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as the insulating layer) / copper foil (conductor layer) / polyvinyl acetal resin film (low dielectric layer) / thin plate glass (protective layer) are laminated in this order, and an antenna circuit board with a protective glass plate is disposed on a part of the glass, in the same manner as in Example 2, except that the above laminate is used instead of the laminate of Example 1. Since the polyvinyl acetal resin film with a thickness of 30 μm is composed of the same polyvinyl acetal resin as the polyvinyl acetal resin film produced in Example 1, it is presumed to have the same dielectric constant. In the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of the glass, it is presumed that the high frequency incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0201] [Example 9] <Fabrication of Antenna System> On the lower glass with a length of 20 cm, a width of 10 cm, a thickness of 3 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01, a dried polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm prepared in Example 1, an antenna circuit board (5 cm long and 5 cm wide) prepared in Example 1, a Teflon (registered trademark) sheet, and an upper glass with a length of 5 cm, a width of 5 cm, and a thickness of 3 mm were stacked and fixed in this order. The antenna circuit board was arranged such that the surface having the circuit was in contact with the polyvinyl acetal resin film. The polyvinyl acetal resin film, the antenna circuit board, and the upper glass were aligned so as to overlap each other. These were heated in a vacuum laminator under vacuum at 140 °C for 15 minutes, then the upper chamber was set to -10 kPa (pressure difference from the lower chamber of about 90 kPa) and held for 15 minutes, and then returned to normal pressure. The Teflon (registered trademark) sheet and the upper glass were removed, and an antenna system was obtained in which a glass (first glass layer) / polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of the antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) were laminated in this order, and the antenna circuit board was disposed on a part of the glass. No partial peeling or foaming was observed in the obtained antenna system, and no disconnection or deformation of the circuit was observed either. Further, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of the glass, the high-frequency wave incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0202] [Example 10] [Fabrication of Antenna System] On a lower glass with a length of 20 cm, a width of 10 cm, a thickness of 3 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01, a dried polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm prepared in Example 1, an antenna circuit board (5 cm in length and 5 cm in width) prepared in Example 1, a dried polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm prepared in Example 1, and a thin plate glass with a length of 5 cm, a width of 5 cm, and a thickness of 1 mm were stacked and fixed in this order. The antenna circuit board was arranged such that the surface having the circuit was in contact with the polyvinyl acetal resin film on the lower glass side. The antenna circuit board was disposed in a region 2 cm or more and 7 cm or less inward from the longitudinal end of the lower glass. Also, the antenna circuit board, the two polyvinyl acetal resin films, and the thin plate glass were aligned so as to overlap each other. These were put into a vacuum bag, decompressed at room temperature, and after 15 minutes, the temperature was raised to 135 °C while maintaining the decompression and held for 30 minutes, then the temperature was lowered and the decompression was released to obtain an antenna system in which glass (the first glass layer) / polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of the antenna circuit board (a multilayer substrate having a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / polyvinyl acetal resin film (low dielectric layer) / thin plate glass (protective layer) were laminated in this order, and an antenna circuit board with a protective glass plate was disposed in a part of the glass. No partial peeling or foaming was observed in the obtained antenna system, nor was there any disconnection or deformation of the circuit. Also, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of the glass, the high frequency incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0203] [Example 11] [Fabrication of Antenna System] Instead of using a polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 50 μm, a plasticized polyvinyl acetal resin film with a length of 5 cm, a width of 5 cm, and a thickness of 0.38 mm used in Example 5 was used. In the same manner as in Example 9, a glass (first glass layer) / plasticized polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of the antenna circuit board (a multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) was laminated in this order, and an antenna system in which an antenna circuit board was disposed on a part of the glass was obtained. In the obtained antenna system, no partial peeling or foaming was observed, and no disconnection or deformation of the circuit was observed. Further, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of the glass, the high-frequency wave incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0204] [Example 12] [Fabrication of Antenna System] On a glass with a length of 20 cm, a width of 10 cm, a thickness of 3 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01, a dried plasticized polyvinyl acetal resin film with a length of 7 cm, a width of 7 cm, and a thickness of 0.38 mm used in Example 5, an antenna circuit board (5 cm in length and 5 cm in width) fabricated in Example 1 at the center of the plasticized polyvinyl acetal resin film, a dried polyvinyl acetal resin film with a length of 7 cm, a width of 7 cm, and a thickness of 50 μm fabricated in Example 1, and a thin plate glass with a length of 7 cm, a width of 7 cm, and a thickness of 1 mm were stacked and fixed in this order. The antenna circuit board was arranged such that the surface having the circuit was in contact with the plasticized polyvinyl acetal resin film. The antenna circuit board was disposed in a region 2 cm or more and 7 cm or less inward from the longitudinal end of the glass. Also, the two polyvinyl acetal resin films and the thin plate glass were aligned so as to overlap each other. These were placed in a vacuum bag, depressurized at room temperature, and after 15 minutes, the temperature was raised to 100 °C while maintaining the vacuum and held for 30 minutes. Then, the temperature was lowered and the vacuum was released for temporary pressure bonding. After that, it was put into an autoclave and treated at 140 °C and 12 MPa for 30 minutes to obtain an antenna system in which glass (the first glass layer) / plasticized polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer board with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / polyvinyl acetal resin film (low dielectric layer) / thin plate glass (protective layer) were laminated in this order, and an antenna circuit board with a protective glass plate was disposed on a part of the glass. No partial peeling or foaming was observed in the obtained antenna system, nor were there any disconnections or deformations in the circuit. Further, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of the glass, the high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0205] [Example 13] [Fabrication of Antenna System] On the lower glass with a length of 30 cm, a width of 30 cm, a thickness of 3 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01, the laminate obtained in Example 1 was stacked so that the polyvinyl acetal resin film (low dielectric layer) was in contact with the lower glass. On top of that, a plasticized polyvinyl acetal resin interlayer film with a length of 30 cm, a width of 30 cm, and a thickness of 0.76 mm, containing 72% by mass of polyvinyl butyral resin (hydroxyl group content 28.8% by mass, viscosity average degree of polymerization 1700) and 28% by mass of triethylene glycol-bis-(2-ethylhexanoate), and an upper glass with a length of 30 cm, a width of 30 cm, and a thickness of 3 mm were stacked and fixed in this order. The antenna circuit board was disposed at the center in the plane direction of the lower glass. These were placed in a vacuum bag, depressurized at room temperature, and after 15 minutes, the temperature was raised to 100 °C while maintaining the vacuum and held for 30 minutes. Then, the temperature was lowered and the vacuum was released for temporary pressure bonding. After that, it was put into an autoclave and treated at 140 °C and 12 MPa for 30 minutes, resulting in a laminated structure of glass (the first glass layer) / polyvinyl acetal resin film (the first low dielectric layer) / circuit (circuit layer) / inner layer of the antenna circuit board (a multilayer substrate with a thermoplastic liquid crystal polymer film as the insulating layer) / copper foil (conductor layer) / plasticized polyvinyl acetal resin interlayer film (the second low dielectric layer) / glass (the second glass layer) in this order, and an antenna system in which the antenna circuit board was sealed inside the laminated glass was obtained. No foaming or significant optical unevenness was observed around the antenna circuit in the obtained antenna system. Also, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of glass, high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0206] [Example 14] [Fabrication of Antenna System] On the lower glass with a length of 30 cm, a width of 30 cm, a thickness of 3 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01, the dried polyvinyl acetal resin film prepared in Example 1 with a length of 7 cm, a width of 7 cm, and a thickness of 50 μm was overlaid. The antenna circuit board (5 cm in length and 5 cm in width) prepared in Example 1 was overlaid and placed at the center of the polyvinyl acetal resin film. Then, the plasticized polyvinyl acetal resin interlayer film with a length of 30 cm, a width of 30 cm, and a thickness of 0.76 mm used in Example 13 and the upper glass with a length of 30 cm, a width of 30 cm, and a thickness of 3 mm were overlaid and fixed in this order. The antenna circuit board was arranged such that the surface having the circuit was in contact with the polyvinyl acetal resin film. Note that the antenna circuit board was disposed at the center in the surface direction of the lower glass. These were placed in a vacuum bag, and the pressure was reduced at room temperature. After 15 minutes, the temperature was raised to 100 °C while maintaining the reduced pressure and held for 30 minutes. Then, the temperature was lowered and the pressure was released to perform temporary pressure bonding. After that, it was put into an autoclave and processed at 140 °C and 12 MPa for 30 minutes, resulting in a laminated structure of glass (the first glass layer) / polyvinyl acetal resin film (the first low dielectric layer) / circuit (circuit layer) / inner layer of the antenna circuit board (a multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / plasticized polyvinyl acetal resin interlayer film (the second low dielectric layer) / glass (the second glass layer) in this order, and an antenna system in which the antenna circuit board was sealed inside the laminated glass was obtained. No foaming or significant optical unevenness was observed around the antenna circuit in the obtained antenna system. Also, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of glass, high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0207] [Example 15] <Fabrication of Antenna System> On a lower glass with a length of 30 cm, a width of 30 cm, a thickness of 3 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01, an ionomer resin film with a length of 7 cm, a width of 7 cm, and a thickness of 50 μm (manufactured by Kuraray Co., Ltd., a film obtained by thinning SentryGlas (registered trademark) SG5000 by hot pressing, a dielectric constant in the X direction of 2.2, a dielectric constant in the Y direction of 2.2, a dielectric tangent in the X direction of 0.002, and a dielectric tangent in the Y direction of 0.002) was overlaid. The antenna circuit board (5 cm long and 5 cm wide) fabricated in Example 1 was overlaid and placed at the center of the polyvinyl acetal resin film. Then, a dried ionomer resin interlayer film with a length of 30 cm, a width of 30 cm, and a thickness of 890 μm (manufactured by Kuraray Co., Ltd., SentryGlas (registered trademark) SG5000) and an upper glass with a length of 30 cm, a width of 30 cm, and a thickness of 3 mm were overlaid and fixed in this order. The antenna circuit board was arranged such that the surface having the circuit was in contact with the ionomer resin film. Note that the antenna circuit board was disposed at the center in the plane direction of the lower glass. These were placed in a vacuum bag, and the pressure was reduced at room temperature. After 15 minutes, the temperature was raised to 100 °C while maintaining the reduced pressure and held for 30 minutes. Then, the temperature was lowered and the pressure was released to perform temporary pressure bonding. After that, it was put into an autoclave and treated at 135 °C and 12 MPa for 30 minutes to obtain an antenna system in which glass (the first glass layer) / ionomer resin film (the first low dielectric layer) / circuit (circuit layer) / inner layer of the antenna circuit board (a multilayer substrate having a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / ionomer resin intermediate film (the second low dielectric layer) / glass (the second glass layer) were laminated in this order, and the antenna circuit board was sealed inside the laminated glass. No foaming or significant optical unevenness was observed around the antenna circuit in the obtained antenna system. Also, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of glass, high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0208] [Example 16] [Fabrication of Antenna System] An appropriate amount of triethylene glycol-di-(2-ethylhexanoate) was applied to the polyvinyl acetal resin film surface of the laminate obtained in Example 1, and it was bonded onto glass having a length of 20 cm, a width of 10 cm, a thickness of 3 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01 so that no air would enter. The antenna circuit board was disposed in a region 2 cm or more and 7 cm or less inward from the longitudinal end of the glass. By heating these in a hot air dryer at 50 °C for 1 hour, an antenna system was obtained in which glass (the first glass layer) / polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of the antenna circuit board (a multilayer substrate having a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) were laminated in this order, and the antenna circuit board was disposed in a part of the glass. No film displacement was observed even when a shearing force was applied to the obtained antenna system. Also, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of glass, high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0209] [Example 17] [Fabrication of Antenna System] An appropriate amount of triethylene glycol-di(2-ethylhexanoate) was applied to the polyvinyl acetal resin film surface of the laminate obtained in Example 3, and it was bonded onto glass with a length of 20 cm, a width of 10 cm, a thickness of 3 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01 so that no air entered. The antenna circuit board was disposed in a region 2 cm or more and 7 cm or less inward from the longitudinal end of the glass. By heating these with a hot air dryer at 50 °C for 1 hour, a laminate was obtained in the order of glass (first glass layer) / polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / polyvinyl acetal resin film (low dielectric layer) / thin plate glass (protective layer), and an antenna system in which an antenna circuit board with a protective glass plate was disposed in a part of the glass was obtained. No film displacement was observed even when a shearing force was applied to the obtained antenna system. Also, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of the glass, high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0210] [Example 18] [Fabrication of Antenna System] An antenna system was obtained in the same manner as in Example 17, except that dibutoxyethyl adipate was used instead of triethylene glycol-di-(2-ethylhexanoate). The layers were laminated in the order of glass (first glass layer) / polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / polyvinyl acetal resin film (low dielectric layer) / thin plate glass (protective layer). An antenna circuit board with a protective glass plate was disposed on a part of the glass. No film displacement was observed even when a shearing force was applied to the obtained antenna system. Also, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of glass, high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0211] [Example 19] [Fabrication of Antenna System] An antenna system was obtained in the same manner as in Example 17, except that the heating in the hot air dryer was changed to 30 °C for 24 hours. The layers were laminated in the order of glass (first glass layer) / polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / polyvinyl acetal resin film (low dielectric layer) / thin plate glass (protective layer). An antenna circuit board with a protective glass plate was disposed on a part of the glass. No film displacement was observed even when a shearing force was applied to the obtained antenna system. Also, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of glass, high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0212] [Example 20] [Fabrication of Antenna System] An antenna system was obtained in the same manner as in Example 18 except that the heating in the hot air dryer was changed to 30°C. It was laminated in the order of glass (first glass layer) / polyvinyl acetal resin film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer) / polyvinyl acetal resin film (low dielectric layer) / thin plate glass (protective layer). An antenna circuit board with a protective glass plate was disposed on a part of the glass. No film displacement was observed even when a shearing force was applied to the obtained antenna system. Further, in the obtained antenna system, since the low dielectric layer has a dielectric constant smaller than that of the glass, the high frequency incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0213] [Example 21] <Fabrication of Antenna Circuit Board> Copper foils (electrolytic copper foil "H9A" manufactured by Fukuda Metal Foil & Powder Co., Ltd., thickness 12 μm) were laminated on both sides of a thermoplastic liquid crystal polymer film (manufactured by Kuraray Co., Ltd., Vectra (registered trademark), thickness 50 μm, dielectric constant in the X direction: 3.4, dielectric constant in the Y direction: 3.4, dielectric tangent in the X direction: 0.002, dielectric tangent in the Y direction: 0.002). Using a vacuum hot press device, the heating plate was set to 290°C, and pressure bonding was performed for 15 minutes under a pressure of 4 MPa to fabricate a copper-clad laminate having a structure of copper foil / thermoplastic liquid crystal polymer film / copper foil. A circuit was formed by removing a part of the copper foil on one surface of the obtained copper-clad laminate with an etching solution, and this operation was repeated to fabricate an antenna circuit board (3 cm long and 3 cm wide) with a thickness of 400 μm.

[0214] <Fabrication of Antenna System> On a glass with a length of 20 cm, a width of 10 cm, a thickness of 3.5 mm, a dielectric constant in the X direction of 6.5, a dielectric constant in the Y direction of 6.5, a dielectric tangent in the X direction of 0.01, and a dielectric tangent in the Y direction of 0.01, a polyvinyl acetal film with a length of 3 cm and a width of 3 cm (manufactured by Kuraray Co., Ltd., V200KE, a thickness of 700 μm, a dielectric constant in the X direction of 2.7, a dielectric constant in the Y direction of 2.7, a dielectric tangent in the X direction of 0.02, and a dielectric tangent in the Y direction of 0.02) was placed such that the upper end of the film was 2 cm below (inward) the upper end of the glass in the longitudinal direction, and the central part of the film in the transverse direction overlapped with the central part of the glass in the transverse direction. On top of that, the antenna circuit board fabricated above was placed such that the surface having the circuit was in contact with the polyvinyl acetal film. Then, with the position of the antenna circuit board held, the glass was placed in a vacuum bag and treated at 100 °C for 30 minutes under reduced pressure. After cooling, the reduced pressure was released, and the antenna circuit board was pre-laminated to the glass. Then, this was put into an autoclave and treated at 140 °C and 1.2 MPa for 30 minutes, obtaining an antenna system in which the antenna circuit board was disposed on a part of the glass in the order of glass (first glass layer) / polyvinyl acetal film (low dielectric layer) / circuit (circuit layer) / inner layer of antenna circuit board (multilayer substrate with a thermoplastic liquid crystal polymer film as an insulating layer) / copper foil (conductor layer). In the obtained antenna system, the thickness df of the low dielectric layer is 700 μm, and it satisfies the range of λ / 4×n±0.050 mm (n = 2) for the high frequency of the target wavelength λ (1.47 mm).

[0215] When a high frequency of wavelength λ is incident from the glass side on the obtained antenna system, since the polyvinyl acetal film is smaller than the glass and has a dielectric constant within the range satisfying the above formula (I), the high frequency incident on the glass can pass through the polyvinyl acetal layer which is the low dielectric layer and reach the antenna circuit board. Also, since the thickness of the low dielectric layer satisfies the range of λ / 4×n±0.050 mm, the high frequency can efficiently reach the antenna circuit board.

[0216] [Example 22] Instead of the low dielectric layer used in Example 21, except for using multiple stacked polyvinyl acetal films [MFR (190 °C, 2.16 kg) 0.75 g / 10 min, thickness 50 μm, dielectric constant in the X direction: 2.5, dielectric constant in the Y direction: 2.5, dielectric tangent in the X direction: 0.01, dielectric tangent in the Y direction: 0.01], when manufacturing the antenna system in the same manner as in Example 21, similar to Example 21, since the low dielectric layer has a dielectric constant smaller than that of glass, the high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0217] [Example 23] Instead of the low dielectric layer used in Example 21, except for using an ionomer film (manufactured by Kuraray Co., Ltd., SGR5000, thickness 1000 μm, dielectric constant in the X direction: 2.2, dielectric constant in the Y direction: 2.2, dielectric tangent in the X direction: 0.002, dielectric tangent in the Y direction: 0.002), when manufacturing the antenna system in the same manner as in Example 21, similar to Example 21, since the low dielectric layer has a dielectric constant smaller than that of glass, the high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0218] [Example 24] Instead of the thermoplastic liquid crystal polymer film of the antenna circuit board used in Example 21, except for using a polyimide film (manufactured by Toray DuPont Co., Ltd., Kapton 300H, thickness 75 μm, dielectric constant in the X direction: 3.3, dielectric constant in the Y direction: 3.3, dielectric tangent in the X direction: 0.007, dielectric tangent in the Y direction: 0.007) and performing the adhesion within the antenna circuit board using SAFY (dielectric constant: 3, dielectric tangent: 0.005) manufactured by Nikkan Kogyo Co., Ltd., which is a low dielectric adhesive, when manufacturing the antenna system in the same manner as in Example 21, similar to Example 21, since the low dielectric layer has a dielectric constant smaller than that of glass, the high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

[0219] [Example 25] Instead of the polyimide film used in Example 24, a polyimide film (manufactured by Kaneka Corporation, Apical NPI, thickness 50 μm, dielectric constant in the X direction: 3.4, dielectric constant in the Y direction: 3.4, dielectric tangent in the X direction: 0.004, dielectric tangent in the Y direction: 0.004) is used. When manufacturing an antenna system in the same manner as in Example 24, as in Example 21, since the low dielectric layer has a dielectric constant smaller than that of glass, the high-frequency waves incident on the glass can pass through the low dielectric layer and reach the antenna circuit board.

Industrial Applicability

[0220] The antenna system of the present invention suppresses high-frequency attenuation, enhances the transmission characteristics of the antenna circuit board with respect to high frequencies, and can exchange a large amount of information. Therefore, for example, in vehicle antenna systems such as so-called connected cars for autonomous driving and constant communication by in-vehicle devices, and small cell base station antenna systems by installing them on building windows and wall surfaces, various civil engineering structures (railway facilities, road facilities, energy facilities, dam and river facilities, water and sewage facilities, airport facilities), etc., it can be usefully used. For example, the antenna system of the present invention can be used by forming a vehicle or building window glass or adhering to a vehicle or building.

[0221] As described above, the preferred embodiments of the present invention have been described with reference to the drawings. However, those skilled in the art will easily assume various changes and modifications within the obvious scope by looking at this specification. Therefore, such changes and modifications are construed as being within the scope of the invention determined by the claims.

Explanation of Reference Numerals

[0222] 100, 200, 300, 400, 500, 600... Antenna system 101, 201, 301, 401, 501, 601... First glass layer 202, 302, 502, 602... Second glass layer 103, 203, 303, 403... Low dielectric layer 503a, 603a… First low dielectric layer 503b, 603b… Second low dielectric layer 104… Circuit layer 105… High frequency insulating layer 106… Conductor layer 107… Antenna circuit board 308… Adhesive layer 408a, 408b… Fixing means 409… Adherend

Claims

1. a first glass layer that is transparent to radio frequency waves; a low dielectric layer having a dielectric constant lower than that of the first glass layer, adjacent to the first glass layer, and transmitting high frequency waves incident from the first glass layer; an antenna circuit board including a high frequency insulating layer adjacent to the low dielectric layer and receiving high frequency waves incident from the low dielectric layer; 1. An antenna system for use at frequencies above 1 GHz, comprising:

2. 10. The antenna system of claim 1, wherein the high frequency insulating layer is made of a thermoplastic liquid crystal polymer or a polyimide.

3. 3. The antenna system according to claim 1, wherein the dielectric constant εg of the first glass layer is 5.5 to 7.5, and the dielectric constant εf of the low dielectric layer is 2.0 to 4.0, as dielectric constants in both one direction in a plane and a direction perpendicular thereto, measured at a frequency of 28 GHz.

4. 4. The antenna system according to claim 1, wherein the dielectric loss tangent tan δg of the first glass layer is 0.05 or less, and the dielectric loss tangent tan δf of the low dielectric layer is 0.05 or less, as dielectric loss tangents in both one direction in a plane and a direction perpendicular thereto, measured at a frequency of 28 GHz.

5. 5. The antenna system according to claim 1, wherein the low dielectric layer is made of at least one selected from the group consisting of polyvinyl acetal resin, olefin-vinyl carboxylate copolymer resin, ionomer resin, and acrylic resin.

6. 6. The antenna system according to claim 1, wherein the high-frequency insulating layer has a dielectric constant εp of 2.0 to 4.0, measured at a frequency of 28 GHz in both one direction in a plane and in a direction perpendicular thereto.

7. 7. The antenna system according to claim 1, wherein the dielectric loss tangent tan δp of the high frequency insulating layer is 0.010 or less as a dielectric loss tangent in both one direction in a plane and a direction perpendicular thereto, measured at a frequency of 28 GHz.

8. 8. The antenna system according to claim 1, wherein the dielectric constant εf of the low dielectric layer and the dielectric constant εp of the high frequency insulating layer are εf / εp=30 / 70 to 60 / 40.

9. 9. An antenna system according to any one of claims 1 to 8, wherein the low dielectric layer has a thickness of λ / 4×n±0.050 mm, where λ is the wavelength of the radio frequency and n is an integer.

10. 10. The antenna system according to claim 1, wherein the first glass layer is made of at least one glass selected from the group consisting of soda-lime glass, borate glass, borosilicate glass, aluminosilicate glass, quartz glass, alkali-free glass, and low-alkali glass.

11. 11. The antenna system according to claim 1, further comprising a second glass layer, and at least a low dielectric layer and an antenna circuit board are disposed between the first glass layer and the second glass layer.

12. An antenna system according to any one of the preceding claims, comprising a glazing on a vehicle or building.

13. 12. An antenna system according to any one of claims 1 to 11, for receiving radio waves while attached to a vehicle, a building or a civil structure.

14. An antenna circuit board for use in the antenna system according to any one of claims 1 to 13.

15. A laminate for use in the antenna system according to any one of claims 1 to 14, comprising an antenna circuit board and a low dielectric layer adjacent to the antenna circuit board.

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