Antenna device and method for manufacturing antenna device

Abstract

To improve the quality of an antenna device having a cavity structure.SOLUTION: The antenna device includes an antenna portion in which a conductive layer and a plurality of first dielectric layers are laminated, a cavity forming portion that is disposed on the antenna portion and in which a plurality of second dielectric layers each having an opening portion formed therein are laminated, the plurality of opening portions communicating with each other to form a wall portion of a cavity having the antenna portion as a bottom surface, and a bonding layer that is disposed between the antenna portion and the cavity forming portion and bonds the antenna portion and the cavity forming portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an antenna device and a method for manufacturing the antenna device. [Background technology]

[0002] A patch antenna having a cavity structure is known (see, for example, Patent Document 1). In Patent Document 1, a base with a cavity formed in its center is disposed on the upper surface of a ground electrode. A patch antenna element is disposed between the ground electrode and the base. An electronic component is mounted in a region that is part of the upper surface of the ground electrode and corresponds to the bottom surface of the cavity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-135041 Summary of the Invention [Problem to be solved by the invention]

[0004] The ground electrode and the base are often manufactured by crimping. In an antenna device having a cavity structure as disclosed in Patent Document 1, the height position of the bottom surface of the cavity differs from the height position of the base forming the cavity. Therefore, when the base and the ground electrode are crimped along the stacking direction during manufacturing of the antenna device, the rubber used as a jig for crimping may not be able to apply sufficient pressure to the bottom surface of the cavity due to the difference in height positions. In this case, there is a risk of a gap being formed between the antenna element located on the bottom surface of the cavity and the ground electrode or base, and of deformation of the antenna element.

[0005] The present invention has been made to solve at least part of the above-mentioned problems, and has an object to improve the quality of an antenna device having a cavity structure. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms.

[0007] (1) According to one aspect of the present invention, there is provided an antenna device comprising: an antenna section including a conductive layer and a plurality of first dielectric layers stacked together; a cavity-forming section disposed on the antenna section and including a plurality of second dielectric layers stacked together, each having an opening formed therein, the openings of the cavity-forming section communicating with each other to form a wall of a cavity having the antenna section as its bottom; and a bonding layer disposed between the antenna section and the cavity-forming section, bonding the antenna section to the cavity-forming section.

[0008] According to this configuration, a bonding layer is present between the antenna portion and the cavity-forming portion, bonding the antenna portion and the cavity-forming portion. That is, in this configuration, the antenna portion and the cavity-forming portion are manufactured separately and then bonded by the bonding layer. Unlike the previous configuration, when the antenna portion and the cavity-forming portion are laminated together and then crimped, the surface of the conductive layer serving as the antenna element present in the cavity and the surface of the cavity that forms the cavity are simultaneously pressurized. The height positions of the surface of the antenna element and the height positions of the cavity-forming portion differ by the depth of the opening of the cavity. Therefore, the jig used during crimping may not properly contact the surface of the antenna element due to the mismatch in height positions, resulting in a risk of different forces being applied to the surface of the antenna element and the cavity-forming portion. In this case, insufficient pressure may be applied to the surface of the antenna element, resulting in gaps between the first dielectric layers of the antenna portion after firing, or cracks due to gases such as degreased binders. In contrast, in this configuration, the antenna portion and the cavity-forming portion are bonded together as separate components, and then joined together. Therefore, there is no misalignment in the depth of the opening formed by the cavity-forming portion during bonding. This prevents gaps caused by insufficient pressure on the surface of the antenna element during bonding, and prevents cracks caused by gases such as degreased binders. As a result, the quality of the antenna device is improved.

[0009] (2) In the antenna device of the above aspect, the bonding layer may include glass. According to this configuration, the melting point of the glass contained in the bonding layer is lower than the melting point of the metal forming the conductive layer. Therefore, the antenna portion and the cavity-forming portion are bonded by the bonding layer at a temperature lower than the melting point of the conductive layer but higher than the melting point of the glass. This allows the antenna portion and the cavity-forming portion to be bonded while suppressing the influence on the conductive layer during bonding using the bonding layer.

[0010] (3) In the antenna device of the above form, when the antenna portion and the cavity-forming portion are viewed from the stacking direction of the second dielectric layer, at least a portion of the outer periphery of the antenna portion may be located outside the outer periphery of the cavity-forming portion. With this configuration, even if the opening formed by the cavity-forming portion is miniaturized, at least a portion of the outer periphery of the antenna portion is located outside the outer periphery of the cavity-forming portion. Therefore, the surface of the antenna portion opposite to the surface bonded to the cavity-forming portion is large, and the area where the connector electrically connected to the conductive layer is disposed is large. As a result, even if the antenna device is miniaturized, the area for connecting the connector can be secured.

[0011] (4) In the antenna device of the above aspect, the first dielectric layer and the second dielectric layer may be made of different ceramic materials. With this configuration, the antenna portion and the cavity-forming portion are laminated separately and then bonded by the bonding layer, allowing the thermocompression bonding conditions for the antenna portion and the cavity-forming portion to be set separately. Therefore, even if the first dielectric layer laminated in the antenna portion and the second dielectric layer laminated in the cavity-forming portion are made of different materials, the thermocompression bonding conditions can be set according to the materials. This allows the first dielectric layer and the second dielectric layer to be formed from different materials depending on the application, thereby increasing the degree of freedom in designing the radiation pattern and size of the antenna device.

[0012] (5) Another aspect of the present invention provides a method for manufacturing an antenna device, comprising: a first compression bonding step of compressing a conductive layer and a plurality of first dielectric layers in a stacked state, a second compression bonding step of compressing a plurality of second dielectric layers, each having an opening formed therein, in a stacked state such that the openings are in communication with each other, a first firing step of firing a first stack of the conductive layer and the plurality of first dielectric layers after the first compression bonding step, a second firing step of firing a second stack of the plurality of second dielectric layers after the second compression bonding step, and a bonding step of bonding the first stack after the first firing step and the second stack after the second firing step with an adhesive. According to this configuration, a first laminate that has undergone a first pressure-bonding step and a first firing step and a second laminate that has undergone a second pressure-bonding step and a second firing step are connected with an adhesive in a bonding step. The first laminate including the conductive layer after bonding functions as an antenna portion of the antenna device. The second laminate having an opening after bonding functions as a cavity-forming portion in which an antenna element of the antenna portion is disposed within the opening. Unlike this configuration, when the pressure-bonding step and the firing step are performed with the first laminate and the second laminate simultaneously stacked, pressure is applied to the surface of the antenna element of the first laminate present within the opening and the surface of the second laminate forming the opening simultaneously. The height position of the bottom of the opening where the antenna element is disposed differs from the height position of the second laminate by the depth of the opening. Therefore, the jig used during pressure-bonding may not properly contact the bottom of the opening due to the mismatch in height positions, which may result in different forces being applied to the surface of the antenna element and the second laminate. In this case, gaps may occur between the first laminates after firing due to insufficient pressure being applied to the bottom of the opening, and cracks may occur due to gases such as degreased binders. In contrast, in this configuration, the first laminate including the antenna element and the second laminate are bonded as separate members in the first and second pressure-bonding steps, respectively, and then joined. This prevents gaps caused by insufficient pressure when pressing due to the height between the bottom of the opening in the second laminate and the portion of the second laminate other than the opening, and cracks caused by gases such as degreased binders.

[0013] (6) In the manufacturing method of the above aspect, the first pressure-bonding step may be performed by pressing the conductive layer and the plurality of first dielectric layers together in a stacked state from both sides along the stacking direction to bond them together, and the second pressure-bonding step may be performed by pressing the plurality of second dielectric layers together in a stacked state from both sides along the stacking direction to bond them together. According to this configuration, in the first and second pressure-bonding steps, the entire surface of each laminate is pressed in the stacking direction, i.e., the entire surface of each laminate is evenly pressure-bonded, thereby suppressing the occurrence of cuts or gaps in the first and second laminates.

[0014] The present invention can be realized in various forms, for example, an antenna device, a wiring board, a system including these, a method for manufacturing an antenna device, a method for manufacturing a wiring board, and a system including these. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic perspective view of an antenna device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic cross-sectional view of the antenna device. [Figure 3] 4 is a flowchart of a method for manufacturing the antenna device of the present embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view of an antenna part to be crimped in a first crimping step. [Figure 5] FIG. 10 is a schematic cross-sectional view of a cavity forming portion to be compressed. [Figure 6] FIG. 10 is a schematic cross-sectional view of a cut antenna portion and a cavity-forming portion. [Figure 7] 10 is a schematic cross-sectional view of the antenna portion and the cavity forming portion in a bonding step. FIG. [Figure 8] 10 is a flowchart of a method for manufacturing an antenna device of a comparative example. [Figure 9] FIG. 10 is a schematic cross-sectional view of a comparative example in which a cavity forming portion and an antenna portion are pressure-bonded together. [Figure 10] FIG. 2 is a schematic cross-sectional view of the vicinity of a bonding layer in an example. [Figure 11] 10 is a schematic cross-sectional view of the vicinity of the boundary between a cavity forming portion and an antenna portion in a comparative example. FIG. [Figure 12] FIG. 10 is an explanatory diagram of the unevenness on the bottom surface of the cavity in the embodiment. [Figure 13] FIG. 10 is an explanatory diagram of irregularities on the bottom surface of a cavity in a comparative example. [Figure 14] FIG. 10 is a schematic cross-sectional view of the vicinity of the bottom surface of a cavity of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0016] <Embodiment> FIG. 1 is a schematic perspective view of an antenna device 1 according to one embodiment of the present invention. The antenna device 1 is used in fields utilizing 5G (5th Generation) communications, such as communications fields for mobile terminals and base stations, factories, offices, beverages, infrastructure, and plant transportation. FIG. 1 shows the antenna device 1 and two connectors CN1 and CN2 connected to a bottom surface 10B of the antenna device 1. As shown in FIG. 1, the antenna device 1 includes an antenna section 10, a cavity-forming section 20 disposed on the top surface of the antenna section 10, and a bonding layer 30 disposed between the antenna section 10 and the cavity-forming section 20.

[0017] In this embodiment, the antenna unit 10 has a flat plate shape having a pair of rectangular upper and lower surfaces 10T and 10B. Fig. 1 shows a Cartesian coordinate system CS. The Cartesian coordinate system CS is composed of an X-axis and a Y-axis parallel to each of two pairs of parallel sides of the flat antenna unit 10, and a Z-axis parallel to the thickness direction and orthogonal to the X-axis and Y-axis. The Cartesian coordinate system CS shown in Fig. 1 corresponds to the Cartesian coordinate system CS shown in Fig. 2 and subsequent figures.

[0018] The cavity-forming portion 20 has two pairs of sides parallel to the X-axis and Y-axis, respectively, and a predetermined thickness direction along the Z-axis. The cavity-forming portion 20 has a rectangular parallelepiped shape with a cavity CV, which is an opening extending along the thickness direction, at the center of the rectangular parallelepiped shape. The cavity-forming portion 20 is disposed on the top surface 10T side of the antenna portion 10. The cavity CV has two pairs of sides parallel to the X-axis and Y-axis, respectively, and is a rectangular parallelepiped space penetrating in the thickness direction. The bottom of the cavity CV is closed by the top surface 10T of the antenna portion 10. Therefore, the cavity-forming portion 20 can be said to form the wall portion of the cavity CV, whose bottom surface is a portion of the top surface 10T of the antenna portion 10. The bonding layer 30 has the same shape as the cavity-forming portion 20 in the XY plane and a predetermined thickness. As shown in FIG. 1, the cavity-forming portion 20 is disposed on the inner periphery of the antenna portion 10 in the XY plane. In other words, when the antenna portion 10 and the cavity-forming portion 20 are viewed from the stacking direction, which is the thickness direction, the outer periphery of the antenna portion 10 is located outside the outer periphery of the cavity-forming portion 20. In Fig. 1, the inside of the cavity CV is indicated by a dashed line.

[0019] Fig. 2 is a schematic diagram of the antenna device 1 taken along the line AA in Fig. 1. The antenna section 10 is formed by laminating three conductive layers 11A to 11C and three ceramic dielectric layers (first dielectric layers) 12A to 12C made of ceramic. The three conductive layers 11A to 11C are electrically connected by a plurality of vias 13 that penetrate the three ceramic dielectric layers 12A to 12C in the thickness direction. The three conductive layers 11A to 11C and the vias 13 are formed from a conductive paste containing Cu (copper).

[0020] Of the three conductive layers 11A-11C, the conductive layer 11A located vertically above is disposed on the top surface 10T of the antenna unit 10, which forms the bottom surface of the cavity CV, and functions as an antenna element. Of the three conductive layers 11A-11C, the conductive layer 11C located vertically below is connected to two connectors CN1 and CN2 disposed on the bottom surface 10B of the antenna unit. The conductive layer 11B is disposed on the top surface of the ceramic dielectric layer 12B. Therefore, the conductive layer 11A, which functions as an antenna element, and the two connectors CN1 and CN2 are electrically connected via the two conductive layers 11B and 11C and multiple vias 13.

[0021] 2, the cavity-forming portion 20 is formed by laminating three ceramic dielectric layers (second dielectric layers) 22A-22C, each having an opening that forms a cavity CV. The ceramic dielectric layers 22A-22C are made of the same material as the ceramic dielectric layers 12A-12C of the antenna portion 10. The bonding layer 30 is disposed between the lower surface 20B of the cavity-forming portion 20 and the upper surface 10T of the antenna portion 10. The bonding layer 30 contains glass. The glass contained in the bonding layer 30 may contain, for example, any of B2O3, SiO2, Bi2O3, and ZnO.

[0022] 3 is a flowchart of a method for manufacturing the antenna device 1 of this embodiment. In the method for manufacturing the antenna device 1 of this embodiment, the antenna section 10 and the cavity-forming section 20 are laminated in separate pressure-bonding steps and then bonded by a bonding layer 30. This suppresses damage near the conductive layer 11A that may occur when the antenna section 10 and the cavity-forming section 20 are pressure-bonded simultaneously.

[0023] In the manufacturing flow shown in Fig. 3, first, a plurality of green sheets, which are materials for the ceramic dielectric layers 12A-12C, 22A-22C, are prepared (step S1). The green sheets are sheets formed by doctor blade processing using a paste whose main component is alumina (Al2O3). The thickness and material of the prepared green sheets vary depending on the ceramic dielectric layers 12A-12C, 22A-22C used in the antenna device 1. An opening corresponding to the cavity CV is formed in each of the green sheets corresponding to the ceramic dielectric layers 22A-22C that form the cavity forming portion 20.

[0024] A plurality of holes are formed in the prepared green sheets by punching (step S2). The formed holes vary in size and shape. The plurality of holes are formed as vias 13 (step S3). A conductive paste containing Cu (copper) is filled into the holes by screen printing, and the vias 13 are formed by punching or laser processing.

[0025] After the vias are formed, a conductive paste containing Cu is applied by screen printing to the green sheets to form the conductive layers 11A-11C (step S4). A pattern of the conductive paste corresponding to each of the conductive layers 11A-11C is formed on the green sheets corresponding to each of the ceramic dielectric layers 12A-12C. In other embodiments, the pattern of the conductive paste corresponding to each of the conductive layers may be formed on both sides of the green sheets.

[0026] A first pressure-bonding step is performed (step S5), in which the conductive layers 11A-11C and the green sheets that will become the ceramic dielectric layers 12A-12C are pressure-bonded together in a stacked state. FIG. 4 is a schematic cross-sectional view of the conductive layers 11A-11C and the green sheets that are pressure-bonded in the first pressure-bonding step. As shown in FIG. 4, the conductive layers 11A-11C and the green sheets are pressure-bonded while being heated from both sides in the stacking direction. In this embodiment, a pressure-bonding solvent is used during pressure-bonding. A well-known pressure-bonding solvent can be used. Note that FIG. 4 shows a cross section in a state where the dimension in the stacking direction is enlarged compared to FIG. 2. Hereinafter, the green sheets that will become the ceramic dielectric layers 12A-12C before firing will also be simply referred to as the ceramic dielectric layers 12A-12C.

[0027] Next, a plurality of green sheets that are to become the ceramic dielectric layers 22A to 22C are pressure-bonded together in blocks to produce blocks corresponding to the ceramic dielectric layers 22A to 22C (step S6 in FIG. 3). Each of the ceramic dielectric layers 22A to 22C is produced by pressure-bonding a plurality of green sheets that are stacked so that the openings are in communication with each other to produce a block. Thereafter, three blocks serving as the ceramic dielectric layers 22A to 22C are pressure-bonded together to form the cavity-forming portion 20 (step S7). Hereinafter, the green sheets or blocks before firing that are to become the ceramic dielectric layers 22A to 22C will also be simply referred to as the ceramic dielectric layers 22A to 22C.

[0028] 5 is a schematic cross-sectional view of the ceramic dielectric layers 22A-22C to be pressure-bonded. The ceramic dielectric layers 22A-22C are laminated so that the openings are in communication with each other, and are pressure-bonded while being heated from both sides in the lamination direction. The processes of steps S6 and S7 correspond to a second pressure-bonding step.

[0029] After the compression bonding, unnecessary portions of the antenna section 10 and the cavity-forming section 20 are cut off so as to conform to the dimensions of the antenna device 1 (step S8 in FIG. 3). FIG. 6 is a schematic cross-sectional view of the cut antenna section 10 and the cavity-forming section 20. FIG. 6(a) shows a schematic cross-sectional view of the antenna section 10, and FIG. 6(b) shows a schematic cross-sectional view of the cavity-forming section 20. As shown in FIGS. 6(a) and 6(b), the outer peripheries of the antenna section 10 and the cavity-forming section 20 in the XY plane perpendicular to the thickness direction are cut off to conform to the dimensions of the antenna device 1. Note that FIG. 6(a) shows a cross-section in a state where the dimensions in the stacking direction are enlarged compared to FIG. 2, similar to FIG. 4.

[0030] A first firing step is performed to degrease and fire the laminate of the conductive layers 11A-11C and the ceramic dielectric layers 12A-12C after cutting (step S9 in FIG. 3). A second firing step is performed to degrease and fire the laminate of the ceramic dielectric layers 22A-22C after cutting (step S10). The firing temperatures and firing times in the first and second firing steps are determined appropriately depending on the materials and sizes of the ceramic dielectric layers 12A-12C and the ceramic dielectric layers 22A-22C.

[0031] A bonding process is performed (step S11) in which the laminate of the antenna portion 10 after the first firing process and the laminate of the cavity-forming portion 20 after the second firing process are bonded together using a bonding agent. FIG. 7 is a schematic cross-sectional view of the antenna portion 10 and the cavity-forming portion 20 during the bonding process. In the bonding process, a bonding agent is applied between the upper surface 10T of the ceramic dielectric layer 12A and the lower surface 20B of the ceramic dielectric layer 22C, and then the two are heated to a temperature at which the bonding agent melts to bond them together, thereby producing the antenna device 1. In this embodiment, a glass paste containing a glass component is used as the bonding agent. The melting point of the glass paste used as the bonding layer 30 is preferably 700°C or lower, and more preferably 600°C or lower.

[0032] After the joining process, connectors CN1 and CN2 are connected to the underside 10B of the antenna section 10 in the manufactured antenna device 1 (step S12 in Figure 3), and an antenna is manufactured in which two connectors CN1 and CN2 are connected to the antenna device 1 shown in Figure 1.

[0033] FIG. 8 is a flowchart of a method for manufacturing an antenna device 1x of a comparative example. The antenna device 1x of the comparative example differs significantly in that multiple blocks constituting a laminate of ceramic dielectric layers 12A-12C that form the cavity-forming portion 20 and the laminate that forms the antenna portion 10 are simultaneously pressure-bonded together and then fired. Therefore, the antenna device 1x of the comparative example does not include the bonding layer 30 of this embodiment. Note that the processes of steps S21 to S24 in the manufacturing flow of the comparative example shown in FIG. 8 are the same as the processes of steps S1 to S4 in the manufacturing flow of this embodiment shown in FIG. 3. Therefore, in the manufacturing flow of the comparative example, the processes from step S25 onwards will be described.

[0034] After the conductive layers 11A-11C are formed (step S24), a plurality of green sheets that are to become the ceramic dielectric layers 22A-22C are pressure-bonded together in blocks to form blocks corresponding to the ceramic dielectric layers 22A-22C (step S25). The process in step S25 is the same as the process in step S9 in FIG. 3.

[0035] The fabricated blocks that form the cavity-forming portions 20 are then pressure-bonded to a laminate that forms the antenna portion 10 (step S26). FIG. 9 is a schematic cross-sectional view of the blocks and antenna portion 10 being pressure-bonded together in a comparative example. FIG. 9(a) shows the blocks and antenna portion 10 to be pressure-bonded before pressure-bonding, as well as the rubber RB, metal plate MP, sheet SE, and stage ST used for pressure-bonding. The rubber RB presses the laminate vertically downward along the stacking direction via the metal plate MP. Meanwhile, because the stage ST is fixed, the pressure of the rubber RB presses the laminate vertically upward via the sheet SE. As a result, the blocks and antenna portion 10 are pressure-bonded together along the stacking direction. In the comparative example, a release paper is used for the sheet SE to prevent the antenna portion 10 from sticking to the stage ST. FIG. 9(a) also shows the cavities CV that form the bases of the antenna devices 1x before cutting.

[0036] The rubber RB is made of resin and elastically deforms. A through hole is formed in the metal plate MP along the thickness direction at a position corresponding to the cavity CV in the XY plane. FIG. 9(b) shows the block, the antenna unit 10, the rubber RB, and a portion of the metal plate MP during compression bonding. As shown in FIG. 9(b), during compression bonding, a portion of the vertically lower side of the rubber RB elastically deforms and enters the cavity CV through the through hole formed in the metal plate MP. As a result, the vertically lower side of the rubber RB presses the conductive layer 11A vertically downward against the upper surface 10T of the antenna unit 10. The same compression bonding solvent as in this embodiment is used for the comparative example.

[0037] After the compression bonding, unnecessary portions of the antenna section 10 and the cavity forming section 20 are cut off so that the dimensions match those of the antenna device 1x (step S27 in FIG. 8). The laminate of the cut cavity forming section 20 and the antenna section 10 is then degreased and fired (step S28). Connectors CN1 and CN2 are connected to the bottom surface 10B of the antenna section 10 in the antenna device 1x manufactured after firing (step S29), and a comparative antenna is manufactured in which the two connectors CN1 and CN2 are connected to the antenna device 1x of the comparative example.

[0038] FIG. 10 is a schematic cross-sectional view of the vicinity of the bonding layer 30 in the example. FIG. 11 is a schematic cross-sectional view of the vicinity of the boundary between the cavity-forming portion 20 and the antenna portion 10 in the comparative example. In the antenna device 1 manufactured by the manufacturing method of this embodiment shown in FIG. 10, adhesion marks due to the influence of the bonding layer 30 were observed between the cavity-forming portion 20 and the antenna portion 10. On the other hand, in the antenna device 1x of the comparative example shown in FIG. 11, the cavity-forming portion 20 and the antenna portion 10 were joined by pressure bonding using an adhesive solution application method using a pressure bonding solvent, so the boundary between the cavity-forming portion 20 and the antenna portion 10 was not clearly observed. Note that in FIG. 11, the position corresponding to the unobserved boundary is indicated by a dashed line to clearly show the boundary between the antenna portion 10 and the cavity-forming portion 20. From the above, it can be seen that adhesion marks due to bonding remain between the cavity-forming portion 20 and the antenna portion 10 in the manufacturing method that performs the bonding process of this embodiment.

[0039] FIG. 12 is an explanatory diagram of the unevenness on the bottom surface of the cavity CV1 of the example. FIG. 13 is an explanatory diagram of the unevenness on the bottom surface of the cavity CV1x of the comparative example. In FIGS. 12 and 13, curves C1 and C1x show the change in height along a straight line that passes through the center of the cavity CV1 or CVx and is parallel to the X-axis on the bottom surface. Note that the antenna device including the cavity CV1 or CV1x shown in FIGS. 12 and 13 differs from the antenna device 1 shown in FIG. 1 in that one connector CN1 is connected to the back side of the bottom surface. Therefore, in FIGS. 12 and 13, the projection position of the connector CN1 connected to the back side of the bottom surface, parallel to the X-axis, is shown as the "connector position." The cavities CV1 and CV1x shown in FIGS. 12 and 13 have the same shape and size.

[0040] In Figures 12 and 13, when the height positions of both ends of the connected connector CN1 on the X axis are set to zero, the change in height position on the X axis is shown by curves C1 and C1x. Figures 12 and 13 also show the maximum-minimum value differences ΔZ and ΔZx, which are the difference between the highest and lowest positions on the bottom surface. The maximum-minimum value difference ΔZ for the example shown in Figure 12 was 20 μm. On the other hand, the maximum-minimum value difference ΔZx for the comparative example shown in Figure 13 was 52 μm.

[0041] 12 and 13, the height of the most recessed position on the X-axis of the region where the connector CN1 is connected is shown as warpage WR and WRx. The warpage WR of the example shown in FIG. 12 was 8 μm. On the other hand, the warpage WRx shown in FIG. 13 was 16 μm. From the maximum-minimum value differences ΔZ and ΔZx between the example and the comparative example, and the warpage WR and WRx between the example and the comparative example, the maximum-minimum value difference ΔZ and warpage WR of the example are smaller than the maximum-minimum value difference ΔZx and warpage WRx of the comparative example. This shows that the bottom surface of cavity CV1 of the example is closer to a flat surface than the bottom surface of cavity CV1x of the comparative example.

[0042] If the maximum-minimum value differences ΔZ, ΔZx or the warpage WR, WRx on the bottom surfaces of the cavities CV1, CV1x are large, there is a risk that the connector CN1 connected by solder may be misaligned or misaligned, which may further affect the reflection characteristics of the antenna device 1. Therefore, it is preferable that the bottom surfaces of the cavities CV1, CV1x have high flatness.

[0043] FIG. 14 is a schematic cross-sectional view of the vicinity of the bottom surface of the cavity CV1x of the comparative example. FIG. 14 shows an enlarged cross-section of the vicinity of the bottom surface of a sample in which cracks CR occurred in the bottom surface of the cavity CV1x and the conductive layer 11A in multiple comparative example samples. In the process of step S26 in the manufacturing flow of the comparative example antenna device 1x shown in FIG. 8, as shown in FIG. 9, a portion of the rubber RB enters the cavity CV, thereby pressurizing the conductive layer 11A and the antenna unit 10 along the stacking direction. However, if the pressurization is insufficient, gas decomposed by degreasing may accumulate between the ceramic dielectric layers 12A-12C during firing (step S28) in the manufacturing flow of the comparative example shown in FIG. 8. The internal pressure of the gas accumulated between the ceramic dielectric layer 12A located vertically above the antenna unit 10 and the adjacent ceramic dielectric layer 12A vertically below the ceramic dielectric layer 12A may increase, causing cracks CR (FIG. 14) to occur in the conductive layer 11A and the ceramic dielectric layer 12A. If cracks CR occur, the antenna device 1x will not function as an antenna. Therefore, as in this embodiment, it is preferable to perform thermocompression bonding in which pressure is applied uniformly and gas does not accumulate between the ceramic dielectric layers 12A to 12C.

[0044] As shown in FIGS. 1 and 2 , the antenna device 1 of this embodiment includes an antenna section 10, a cavity-forming section 20 disposed on the upper surface of the antenna section 10, and a bonding layer 30 disposed between the antenna section 10 and the cavity-forming section 20. The cavity-forming section 20 forms the wall of a cavity CV, the bottom of which is a portion of the upper surface 10T of the antenna section 10. In this embodiment, the antenna section 10 and the cavity-forming section 20 are manufactured separately and then bonded together. Therefore, as shown in FIG. 10 , the bonding layer 30 is present in the antenna device 1. When the antenna section 10 and the cavity-forming section 20 are simultaneously laminated and pressure-bonded together, as in a comparative example different from this embodiment, the height position at which the load is applied by the rubber RB differs, as shown in FIG. 9 . Specifically, the height position of the conductive layer 11A functioning as an antenna element and the height position vertically above the cavity-forming section 20 differ depending on the depth of the cavity CV. Therefore, the rubber RB used during compression bonding may not properly contact the surface of the conductive layer 11A due to the mismatch in height, which may result in different forces being applied to the surface of the conductive layer 11A and the vertically upper side of the cavity-forming portion 20. In this case, gaps may form between the ceramic dielectric layers 12A-12C of the antenna unit 10 after firing due to insufficient pressure being applied to the surface of the conductive layer 11A, or cracks CR may occur due to gases such as degreased binders. In contrast, in this embodiment, the antenna unit 10 and the cavity-forming portion 20 are bonded together after being compressed as separate components. Therefore, when the antenna unit 10 and the cavity-forming portion 20 are compressed together, there is no misalignment in the depth of the cavity CV formed by the cavity-forming portion 20, as occurs in the comparative example. As a result, gaps due to insufficient pressure being applied to the surface of the conductive layer 11A during compression bonding and cracks CR due to gases such as degreased binders are suppressed, thereby improving the quality of the antenna device 1.

[0045] Furthermore, the bonding layer 30 of this embodiment contains glass. The melting point of the glass contained in the bonding layer 30 is lower than the melting point of the metal forming the conductive layers 11A to 11C. Therefore, the antenna portion 10 and the cavity-forming portion 20 are bonded by the bonding layer 30 at a temperature lower than the melting point of the conductive layers 11A to 11C and higher than the melting point of the glass. This allows the antenna portion 10 and the cavity-forming portion 20 to be bonded while suppressing the influence on the conductive layers 11A to 11C during bonding using the bonding layer 30.

[0046] Furthermore, when the antenna section 10 and the cavity-forming section 20 of this embodiment are viewed in the stacking direction, which is the thickness direction, the outer periphery of the antenna section 10 is located outside the outer periphery of the cavity-forming section 20. In this embodiment, even if the cavity CV formed by the cavity-forming section 20 is miniaturized, the outer periphery of the antenna section 10 is located outside the outer periphery of the cavity-forming section 20. Therefore, the surface of the antenna section 10 opposite to the surface bonded to the cavity-forming section 20 is larger, and therefore the area where the connectors CN1 and CN2 electrically connected to the conductive layers 11A to 11C are disposed is larger. As a result, even if the antenna device 1 is miniaturized, an area for connecting the two connectors CN1 and CN2 corresponding to vertically polarized waves and horizontally polarized waves can be secured.

[0047] 3, in the manufacturing method of the antenna device 1 of this embodiment, a first compression bonding step is performed in which the conductive layers 11A-11C and the green sheets that will become the ceramic dielectric layers 12A-12C are laminated and compressed together (step S5). Thereafter, three blocks serving as the ceramic dielectric layers 22A-22C are compressed together to form the cavity-forming portion 20 (step S7). A bonding step is performed in which the laminate of the conductive layers 11A-11C and the ceramic dielectric layers 12A-12C after the first firing step is bonded to the laminate of the ceramic dielectric layers 22A-22C after the second firing step using a bonding agent (step S11). The laminate including the conductive layers 11A-11C and the ceramic dielectric layers 12A-12C after the bonding step functions as the antenna section 10 of the antenna device 1. After the bonding step, the laminate of ceramic dielectric layers 22A-22C having a cavity CV functions as a cavity-forming portion 20 in which the conductive layer 11A of the antenna portion 10 is disposed within the cavity CV. When the laminate that forms the antenna portion 10 and the laminate that forms the cavity-forming portion 20 are simultaneously stacked as shown in FIG. 8 and then subjected to the compression bonding step (step S26), as in a comparative example different from the present configuration, the height positions at which pressure is applied differ. Specifically, as shown in FIG. 9, the height positions at which the rubber RB contacts the surface of the conductive layer 11A present within the cavity CV and the vertically upper positions of the laminate that forms the cavity-forming portion 20 differ depending on the depth of the cavity CV. Therefore, the mismatch in height positions causes variations in the force with which the rubber RB presses the surface of the conductive layer 11A, potentially resulting in different forces being applied to the surface of the conductive layer 11A and the upper side of the cavity-forming portion 20. In this case, gaps may occur between the ceramic dielectric layers 12A-12C after firing due to insufficient pressure being applied to the bottom of the cavity CV, and cracks CR may occur due to gases such as degreased binders.In contrast, in this embodiment, the laminate including the conductive layer 11A and the laminate that will become the cavity forming portion 20 are bonded as separate members in a first compression bonding step and a second compression bonding step, and then joined.Therefore, the occurrence of gaps due to insufficient pressure applied depending on the height position during compression bonding, and cracks CR and gaps caused by gases such as degreased binders, as in the comparative example, are suppressed.

[0048] In the manufacturing method of the antenna device 1 of this embodiment, as shown in Fig. 4, the conductive layers 11A-11C and the green sheets are heated and pressure-bonded from both sides in the stacking direction. Furthermore, as shown in Fig. 5, each of the ceramic dielectric layers 22A-22C is stacked so that the openings are connected, and is heated and pressure-bonded from both sides in the stacking direction. In this embodiment, in the first pressure-bonding step and the step of compressing each block of the ceramic dielectric layers 22A-22C to form the cavity-forming portion 20, each laminate is pressed from the entire surface in the stacking direction. That is, since the entire surface of each laminate is evenly compressed, the occurrence of cracks CR and gaps in the antenna portion 10 and the cavity-forming portion 20 is suppressed.

[0049] <Modification of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0050] In the above embodiment, an example of the antenna device 1 including the antenna section 10 and the cavity-forming section 20 bonded by the bonding layer 30 has been described. However, the antenna device 1 can be deformed to the extent that the antenna section 10 and the cavity-forming section 20 are bonded by the bonding layer 30. For example, the bonding layer 30 does not need to contain glass. It is preferable that the melting point of the bonding layer 30 is lower than the temperature of the first baking step (step S9 in FIG. 3) and the temperature of the second baking step (step S10).

[0051] The shapes of the antenna section 10 and the cavity-forming section 20 can be modified. For example, the cavity-forming section 20 may form a cylindrical cavity CV. When viewed from the stacking direction, the outer periphery of the antenna section 10 does not have to be located outside the outer periphery of the cavity-forming section 20. The outer periphery of the antenna section 10 and the outer periphery of the cavity-forming section 20 may be the same. A part of the outer periphery of the antenna section 10 may be located outside the outer periphery of the cavity-forming section 20.

[0052] The ceramic dielectric layers 12A-12C of the antenna unit 10 may be made of different materials than the ceramic dielectric layers 22A-22C of the cavity-forming portion 20. The manufacturing method of this embodiment shown in FIG. 3 differs from the manufacturing method of the comparative example shown in FIG. 8 in that the firing temperatures for the ceramic dielectric layers 12A-12C and the ceramic dielectric layers 22A-22C can be set separately. This allows for differences in firing temperatures and shrinkage rates between the antenna unit 10 and the cavity-forming portion 20 due to differences in materials, and allows for different thermocompression bonding conditions to be set separately. In other words, the ceramic dielectric layers 12A-12C of the antenna unit 10 and the ceramic dielectric layers 22A-22C of the cavity-forming portion 20 can be made of different materials depending on the application, which provides greater flexibility in designing the radiation pattern and size of the antenna device 1.

[0053] 3 can be modified as long as it includes a first pressure-bonding step (step S5) of pressure-bonding the conductive layers 11A-11C and the ceramic dielectric layers 12A-12C, a second pressure-bonding step (steps S7 and S8), and a joining step (step S11) of joining the antenna portion 10 and the cavity-forming portion 20. For example, the cavity-forming portion 20 may be created by pressure-bonding a plurality of green sheets as a process in step S7, without producing a block in step S6.

[0054] In the processing of steps S5 to S7 in FIG. 3, as shown in FIGS. 4 and 5, the laminate of the antenna portion 10 and the cavity-forming portion 20 is pressed against each other in the stacking direction to be pressure-bonded. However, the pressure-bonding method can be modified, and any known pressure-bonding method can be used. Furthermore, as the pressure-bonding method in steps S5 to S7, an adhesive solution application method was used, in which an adhesive solution is applied to the green sheets, the green sheet surfaces are swelled, and the green sheets are laminated at low pressure and low temperature, as in the above embodiment. However, other methods, such as thermocompression bonding, may also be used. In thermocompression bonding, the binder contained in the green sheets is plasticized by heat and pressure, resulting in lamination. Unlike bonding using a bonding layer 30, the adhesive solution application method and thermocompression bonding do not have a visible layer corresponding to the bonding layer 30 shown in FIG. 10.

[0055] This aspect has been described above based on embodiments and modifications. However, the above-described embodiments are intended to facilitate understanding of this aspect and are not intended to limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents thereof are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0056] The present invention can also be realized in the following forms. [Application example 1] An antenna device, an antenna portion in which a conductive layer and a plurality of first dielectric layers are laminated; a cavity forming portion disposed on the antenna portion and including a plurality of second dielectric layers stacked one on the other, each having an opening formed therein, the plurality of openings communicating with each other to form a wall portion of a cavity having the antenna portion as a bottom surface; a bonding layer disposed between the antenna portion and the cavity forming portion, and bonding the antenna portion and the cavity forming portion together. An antenna device comprising: [Application example 2] The antenna device according to Application Example 1, The bonding layer includes glass. An antenna device comprising: [Application example 3] The antenna device according to Application Example 1 or Application Example 2, When the antenna portion and the cavity-forming portion are viewed from the stacking direction of the second dielectric layer, at least a part of the outer periphery of the antenna portion is located outside the outer periphery of the cavity-forming portion. An antenna device comprising: [Application example 4] The antenna device according to any one of Application Examples 1 to 3, The first dielectric layer and the second dielectric layer are formed of different ceramic materials. An antenna device comprising: [Application example 5] A method for manufacturing an antenna device, comprising: a first compression bonding step of compressing the conductive layer and the plurality of first dielectric layers in a stacked state; a second compression bonding step of compressing a plurality of second dielectric layers, each having an opening formed therein, in a stacked state so that the openings are in communication with each other; a first firing step of firing a first laminate of the conductive layer and the plurality of first dielectric layers after the first pressure bonding step; a second firing step of firing a second laminate of the plurality of second dielectric layers after the second pressure bonding step; a bonding step of bonding the first laminated body after the first firing step and the second laminated body after the second firing step with an adhesive. A manufacturing method characterized by: [Application Example 6] The manufacturing method according to Application Example 5, The first pressure-bonding step includes pressing the conductive layer and the plurality of first dielectric layers together from both sides in a stacking direction to bond them together, In the second pressure-bonding step, a plurality of the second dielectric layers are pressed against each other in a stacking direction to be pressure-bonded. A manufacturing method characterized by: [Explanation of symbols]

[0057] 1...Antenna device 1x...Antenna device of comparative example 10...Antenna section 10B...Underside of antenna 10T...Top of antenna 11A~11C…Conductive layer 12A to 12C: Ceramic dielectric layer (first dielectric layer) 13...Beer 20...Cavity forming portion 20B...lower surface of cavity forming portion 22A to 22C: Ceramic dielectric layer (second dielectric layer) 30...Joining layer CN1, CN2...connectors CR…Crack CV, CV1, CV1x...cavity

Claims

1. An antenna device, an antenna portion in which a conductive layer and a plurality of first dielectric layers are stacked; a cavity forming portion disposed on the antenna portion and including a plurality of laminated second dielectric layers each having an opening formed therein, the plurality of openings communicating with each other to form a wall portion of a cavity having the antenna portion as a bottom surface; a bonding layer disposed between the antenna portion and the cavity forming portion, and bonding the antenna portion and the cavity forming portion together. An antenna device comprising:

2. 2. The antenna device according to claim 1, The bonding layer includes glass. An antenna device comprising:

3. 2. The antenna device according to claim 1, When the antenna portion and the cavity-forming portion are viewed from the lamination direction of the second dielectric layer, at least a part of the outer periphery of the antenna portion is located outside the outer periphery of the cavity-forming portion. An antenna device comprising:

4. The antenna device according to any one of claims 1 to 3, The first dielectric layer and the second dielectric layer are formed of different ceramic materials. An antenna device comprising:

5. A method for manufacturing an antenna device, comprising: a first compression bonding step of compressing the conductive layer and the plurality of first dielectric layers in a stacked state; a second compression bonding step of compressing a plurality of second dielectric layers, each having an opening formed therein, in a stacked state so that the plurality of openings are in communication with each other; a first firing step of firing a first laminate of the conductive layer and the plurality of first dielectric layers after the first pressure bonding step; a second firing step of firing a second laminate of the plurality of second dielectric layers after the second pressure bonding step; a bonding step of bonding the first laminate after the first firing step and the second laminate after the second firing step with an adhesive. A manufacturing method characterized by:

6. The manufacturing method according to claim 5, The first pressure-bonding step includes pressing the conductive layer and the plurality of first dielectric layers together from both sides in a stacking direction to bond them together, In the second pressure-bonding step, a plurality of the second dielectric layers are pressed against each other in a stacking direction to be pressure-bonded. A manufacturing method characterized by:

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