EP2083473A1

EP2083473A1 - Antenna device

Info

Publication number: EP2083473A1
Application number: EP09000532A
Authority: EP
Inventors: Susuma Nakajima; Masahiko Nakatsugawa; Keita Inaki; Tadaaki Onishi
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 2008-01-28
Filing date: 2009-01-15
Publication date: 2009-07-29
Also published as: JP2009177660A

Abstract

Provided is an antenna device which allows high density packaging of an electrical component. The antenna device includes: a base body (2) mounted on a circuit board (90); a wiring conductor (50) to which power is supplied, and a radiation conductor (31) which is connected to the wiring conductor (50) to radiate radio waves, each of which is provided on the base body (2); an insulation substrate (82) mounted on the base body (2); and an electrical component (84) which is mounted on the insulation substrate (82) in a chip shape to be electrically connected to the wiring conductor (50). The base body (2) has a stepped portion formed from a top surface (4) of the base body (2) toward the circuit board (90) to form a concave portion (16), and the concave portion (16) allows the antenna to have a lower height.

Description

Cross Reference to Related Applications

The present invention contains subject matter related to Japanese Patent Application No. 2008-015836 filed in the Japanese Patent Office on January 28, 2008, the entire contents of which being incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to an antenna device suitable for a small antenna used for a mobile device.

2. Related Art

This type of antenna device performs radio wave transmission and reception. Specifically, the device is mounted on a motherboard, and the board has a desired high-frequency circuit. The device converts electric energy at a high frequency produced by a corresponding circuit into a radio wave and emits the radio wave in the air. In addition, the device receives a radio wave in the air and converts the radio wave into electric energy at a high frequency to be input to a corresponding circuit.
Recently, with the demand for decreasing the size of mobile devices, structures employing small antenna devices have been introduced. The antenna device includes a radiation conductor mounted on a base body in a substantially prismatic shape, and the radiation conductor is formed in, for example, a spiral shape, has a central axis substantially aligned with a longitudinal axis of the base body, and emits a radio wave in the air (see JP-A-2005-210680 ).
Meanwhile, the aforementioned energy has to be transmitted between the radiation conductor and a power supply wire of the motherboard without losses. Therefore, impedance matching is performed, and the radiation conductor and the power supply wire are connected to each other so as not to cause energy losses.

SUMMARY

However, the antenna device disclosed in JP-A-2005-210680 has a problem in that the mother board needs a large space. This is because a circuit for the matching is mounted on the motherboard.
In an antenna apparatus disclosed in JP-A-2003-229717 , an electrical component used for matching in a chip shape is directly mounted on a base body. Here, there is a problem in that high density packaging of the electrical component is difficult.
Therefore, even though the aforementioned techniques are combined, there is no particular consideration for small antenna devices to be implemented with high density packaging of electrical components.
It is desirable to provide an antenna device which allows high density packaging of an electrical component.
According to an aspect of the invention, the antenna device includes: a base body mounted on a circuit board; a wiring conductor to which power is supplied, and a radiation conductor which is connected to the wiring conductor to radiate radio waves, each of which is provided on the base body; an insulation substrate mounted on the base body; and an electrical component which is mounted on the insulation substrate in a chip shape to be electrically connected to the wiring conductor.
In the antenna device according to the aspect, the electrical component in the chip shape may not be directly mounted on the base body but mounted on the insulation substrate. Therefore, as compared with a case where the electrical component is directly mounted on the base body, high density packaging of the electrical component is possible.
In addition, the insulation substrate having the electrical component is not mounted on the circuit board but mounted on the base body. Therefore, as compared with a case where the insulation substrate is mounted on the circuit board, the circuit board requires a smaller space.
Preferably, the base body may have a stepped portion formed from a top surface of the base body toward the circuit board to form a concave portion in which the insulation substrate is mounted, and the concave portion may be configured such that the electrical component is substantially at the same height as or lower than the top surface.
As described above, when the concave portion is configured such that the electrical component is substantially at the same height as or lower than the top surface of the base body, a top portion of the electrical component does not protrude from the top surface of the base body. As a result, the antenna device can be implemented to have a lower height.
In addition, the base body may be made of resin, and the wiring conductor may be made of metal to be formed integrally with the base body.
When the wiring conductor made of metal is formed integrally with the base body made of resin, the wiring conductor cannot be easily separated from the base body, and this enhances reliability of the antenna device. Here, when the wiring conductor is formed integrally with the base body, the wiring conductor cannot be formed in a very small pattern. However, as described above, the electrical component is mounted on the insulation substrate. Accordingly, although the wiring conductor is formed integrally with the base body, high density packaging of the electrical component is possible.
In addition, the wiring conductor may have a convex portion which is exposed from the base body and connected to a terminal of the insulation substrate with solder.
Accordingly, a joint area between the convex portion and the solder increases, and the solder extends to surround the convex portion, so that joint strength between the convex portion and the solder can be increased. In addition, without using a solder register for the base body, connection between the wiring conductor and the insulation substrate is possible.
In addition, the convex portion may be formed by deforming the wiring conductor in a thickness direction. In this case, the convex portion can be solidly formed.
In addition, the base body may have a plurality of holes.
Since a linear expansion coefficient of the conductor made of metal is different from that of the base body made of resin, a deformation due to thermal stress may occur in the antenna device. However, when the aforementioned holes are provided, as compared with an antenna without holes, a degree of the deformation can be controlled. In addition, a mass of the resin is reduced, so that the lightweight antenna device can be implemented. As a result, for example, during a drop test, the antenna device could withstand drop impact. This result contributes to a reliability improvement of the antenna device.
According to the aspect of the invention, the antenna device which allows high density packaging of the electrical component and is formed to have a lower height can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view illustrating a chip antenna mounted on a motherboard according to an embodiment.
Fig. 2 is a top view illustrating the antenna of Fig. 1.
Fig. 3 is a side view illustrating the antenna of Fig. 1.
Fig. 4 is a bottom view illustrating the antenna of Fig. 1.
Fig. 5 is a perspective view illustrating the antenna of Fig. 1 excluding a matching circuit.
Fig. 6 is a longitudinal sectional view illustrating the antenna of Fig. 1.
Fig. 7 is a perspective view illustrating a conductor pattern of Fig. 1.
Fig. 8 is a bottom view illustrating the conductor pattern of Fig. 7.
Fig. 9 is a perspective view illustrating the conductor pattern of Fig. 7 formed by using a hoop material.
Fig. 10 is bottom view illustrating the hoop material of Fig. 9.
Fig. 11 is a perspective view illustrating the insert-molded hoop material of Fig. 9.
Fig. 12 is a transverse sectional view illustrating a state where the antenna of Fig. 5 is cut from the hoop material of Fig. 11.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.
Referring to Fig. 1, a chip antenna (antenna device) according to an embodiment is mounted on a motherboard (circuit board) 90. The antenna 1 is included in a mobile device such as a mobile phone and can receive digital terrestrial television broadcasting.
The antenna 1 according to the embodiment includes a base body 2 made of a dielectric material such as resin, and the base body 2 is formed substantially in a shape of a rectangular pipe.
Specifically, as illustrated in Figs. 2 and 4 in addition to Fig. 1, the base body 2 has a top surface 4 and a bottom surface 6 formed in a substantially rectangular shape, and the bottom surface 6 faces the board 90. In addition, as illustrated in Fig. 3, longer sides of the top and bottom surfaces 4 and 6 are connected to corresponding side surfaces 10 and 10.
The side surface 10 has a stepped portion 12 formed in a lengthwise direction (longitudinal direction) of the base body 2. There is an increase in thickness of the stepped portion 12 in a direction from the top surface 4 toward the bottom surface 6. More specifically, an area of the bottom surface 6 is larger than that of the top surface 4, and a cross-section of the base body 2 in a width direction (transverse direction) substantially perpendicular to the lengthwise direction has a convex-up shape.
On a front end side of the antenna 1, short sides of the top and bottom surfaces 4 and 6 are connected to a front end surface 8. On a rear end surface of the antenna 1, a concave portion 16 is formed between short sides of the top and bottom surfaces 4 and 6 and a rear end surface 22.
Specifically, the base body 2 has the concave portion 16 caused by a stepped portion formed from the top surface 4 toward the board 90 on the rear end side of the antenna 1. The concave portion 16 has a top surface 18 and a bottom surface 20 (see Figs. 4 and 5), and on the top surface 18, a matching circuit 80 is mounted (see Fig. 1). The matching circuit 80 has an insulation substrate 82 with a predetermined circuit pattern. The substrate 82 has the substantially the same size as the top surface 18, and an electrical component 84 in a chip shape is mounted on a surface of the substrate 82.
As illustrated in Fig. 3, the concave portion 16 is configured such that the electrical component 84 is substantially at the same height as or lower than the top surface 4 of the base body 2.
The base body 2 according to the embodiment is provided with an insert-molded conductor pattern 30 formed by plating Ni/Au on Corson Cu, and portions of the pattern 30 are exposed from the base body 2.
Specifically, as illustrated in Fig. 7, the conductor pattern 30 is constituted by a radiation conductor 31 and a wiring conductor 50, and the radiation conductor 31 and the wiring conductor 50 are connected in the longitudinal direction of the base body 2.
The radiation conductor 31 according to the embodiment is formed in a spiral shape, and a central axis of the radiation conductor 31 is substantially aligned with a longitudinal axis of the base body 2.
More specifically, a cross-section of the radiation conductor 31 in a width direction of the base body 2, that is, in a direction substantially perpendicular to a central axis of the spiral, is substantially octagonal. The conductor 31 includes upper conductor portions 32 provided to the top surface 4 of the base body 2. According to the embodiment, 8 conductor portions 32 including a radiation electrode 38 that is disposed on the front end side of the antenna 1 are disposed in the width direction of the base body 2 and extended in parallel with the board 90. Each of the conductor portions 32 is provided with oblique sides 32a and 32a at both ends.
The radiation electrode 38 has a larger area than the 7 upper conductor portions 32 and radiates radio waves in the air.
In addition, the radiation conductor 31 includes lower conductor portions 34 provided to the bottom surface 6 of the base body 2. According to the embodiment, 8 conductor portions 34 are disposed in the width direction of the base body 2. Specifically, of the corresponding conductor portions 34, one is disposed between the radiation electrode 38 and the upper conductor portion 32, one is disposed between the adjacent two upper conductor portions 32, and one is disposed between the upper conductor portion 32 and the wiring conductor 50. The conductor portions 34 are extended in parallel with the board 90, and each of the conductor portions 34 is provided with oblique sides 34a and 34a at both ends.
The radiation electrode 38, the 7 upper conductor portions 32, and the 8 lower conductor portions 34 are disposed alternately in the central axial direction of the spiral with connection portions 36 interposed therebetween, as illustrated in Fig. 8 as well as in Fig. 7.
Specifically, an end of the radiation electrode 38 is connected to the connection portion 36, and the connection portion 36 is connected to an end of the lower conductor portion 34. The other end of the lower conductor 34 is connected to another connection portion 36, and the connection portion 36 is connected to an end of the upper conductor portion 32.
In addition, the other end of the upper conductor portion 32 is connected to another connection portion 36, and the connection portion 36 is connected to an end of another lower conductor portion 34. In this manner, the upper conductor portions 32, the lower conductor portions 34, and the connection portions 36 are connected in a direction from the front end side to the rear end side of the antenna 1.
Specifically, the connection portion 36 is formed integrally with the upper conductor portion 32 and the lower conductor portion 34 and constituted by an upper connection portion 36a connected to the oblique side 32a of the upper conductor portion 32, a lower connection portion 36b connected to the oblique side 34a of the lower conductor portion 34, and an intermediate connection portion 36c connecting the upper connection portion 36a to the lower connection portion 36b.
The intermediate connection portion 36c is formed in the central axial direction of the spiral, and along with the conductor portions 32 and 34, extended to be parallel with the board 90. A lower surface of the connection portion 36c is engaged with the stepped portion 12 (see Fig. 5).
In addition, one intermediate connection portion 36c is connected to one upper connection portion 36a and one lower connection portion 36b and supports the upper conductor portion 32 and the lower conductor portion 34 with the oblique sides 32a and 34a interposed therebetween (see Figs. 7 and 8).
The upper conductor portion 32 supported by the upper connection portion 36a is supported by the other upper connection portion 36a provided to the other intermediate connection portion 36c with the oblique side 32a at the opposite side.
In addition, the other lower connection portion 36b provided to the other intermediate connection portion 36c supports the other lower conductor portion 34 adjacent to this upper conductor portion 32.
As described above, the radiation electrode 38, the 7 upper conductor portions 32, and the 8 lower conductor portions 34 are connected in the direction from the front end side to the rear end side of the antenna 1, and a plan view or a bottom view of the antenna 1 shows a substantially meander shape. In addition, a length of the radiation conductor 31 corresponds to, for example, an about 1/4 wavelength of a radio wave.
Here, in the radiation conductor 31, the first to third lower conductor portions 34 from the front end side of the antenna 1 are each provided with a convex portion 42, and the eighth from the front end side of the antenna, that is, the first lower conductor portion 34 from the rear end side of the antenna 1 is also provided with a convex portion 42 (see Figs. 6, 8, and so on).
The convex portion 42 is formed by deforming the lower conductor portion 34 by a drawing process in a thickness direction thereof so as to have a substantially rectangular shape, and a longitudinal axis of each convex portion 42 is substantially perpendicular to the central axis of the spiral.
In addition, the four convex portions 42 protrude from the bottom surface 6 of the base body 2 toward the board 90 and are each exposed from the bottom surface 6 to be connected to an open wire of the board 90 with solder.
A boundary portion between the radiation conductor 31 and the wiring conductor 50 is divided into two branches. Specifically, as illustrated in Figs. 7 and 8, at this branch point, first, an installation portion 46 extended from the lower conductor portion 34 is formed in a direction substantially perpendicular to the central axis of the spiral. Accordingly, the convex portion 42 formed at the installation portion 46 has substantially the same length as that of the other convex portion 42.
At the branch point, a connector 44 is provided. The connector 44 is extended in the central axial direction of the spiral to be connected to the wiring conductor 50.
The wiring conductor 50 includes a power supply electrode 52, a GND electrode 54, and a circuit electrode 60. According to the embodiment, the circuit electrode 60 is disposed at a vicinity of the connector 44, the GND electrode 54 is disposed to be adjacent to the rear end surface 22, and the power supply electrode 52 is disposed between the GND electrode 54 and the circuit electrode 60.
At proper positions in the circuit electrode 60, two convex portions 64 are formed. The convex portion 64 of the circuit electrode 60, the power supply electrode 52, and the GND electrode 54 are formed by a drawing process to protrude from the bottom surface 22 toward the board 90 (see Figs. 4, 8, and so on) and exposed from the bottom surface 20. The power supply electrode 52 is connected to a power supply wire of the board 90 with solder and is supplied with a power supply voltage or a control voltage from a high-frequency circuit such as a tuner module.
The GND electrode 54 and the convex portion 64 of the circuit electrode 60 are connected to a grounding wire of the board 90 and the open wire of the board 90 with solder, respectively.
As described above, the aforementioned convex portions 42 and 64 are formed at the radiation conductor 31 and the wiring conductor 50, respectively, and the antenna 1 according to the embodiment is supported by the convex portions 42 and 64 at both end portions in the longitudinal direction of the base body 2. In addition, the convex portions may be formed at both ends (portions nearest to the front end surface 8 and the rear end surface 22) of the base body 2.
Convex portions 62 protruding upward from the top surface 18 are formed at the power supply electrode 52, the GND electrode 54, and the connector 44 of the circuit electrode 60.
Specifically, the power supply electrode 52, the GND electrode 54, and the connector 44 of the circuit electrode 60 penetrate the top surface 18 and the bottom surface 20. In addition, as illustrated in Figs. 5 and 7, at proper positions in the power supply electrode 52, the GND electrode 54, and the connector 44 of the circuit electrode 60, the total 6 convex portions 62 are formed by the drawing process and exposed from the top surface 18 to be connected to a terminal of the insulation substrate 82 with solder.
As described above, the wiring conductor 50 is connected to the power supply wire of the board 90 to be supplied with power and connected to the matching circuit 80. The electrical component 84 of the matching circuit 80 performs matching so that energy losses during transmission between the power supply wire of the board 90 and the radiation conductor 31 do not occur.
On the insulation substrate 82 according to the embodiment, in addition to the electrical component 84 for performing impedance matching, a tuning circuit is mounted. The tuning circuit has a variable-capacitance diode. When a voltage applied to the diode is controlled, accurate channel selection or changing an effective length of the radiation conductor 31 is possible.
When the aforementioned antenna 1 is to be manufactured, first, a single metal thin plate in a hoop shape is prepared.
Next, punching is performed on the thin plate to form the radiation conductor 31 and the wiring conductor 50. In addition, according to the embodiment, a case where a single antenna 1 is manufactured is described. However, when a plurality of antennas 1 are to be manufactured, the punching is performed on a long thin plate to form a plurality of conductors 31 and 50.
As illustrated in Fig. 9, a hoop material 70 is formed by using the thin plate. The hoop material 70 is partitioned into a large frame 72 and a small frame 72 formed inside, and legs 79 are formed at the front end side and the rear end side of the antenna 1 for connection between the large frame 72 and the small frame 76. On the small frame 76, the punching is performed to form the radiation conductor 31, that is, the aforementioned radiation electrode 38, the upper conductor portion 32, the lower conductor portion 34, the connection portion 36, and the connector 44 and to enable the connection portion 36 to be connected to the small frame 76.
In addition, on the small frame 76, the punching is performed to form the wiring conductor 50, that is, the power supply electrode 52, the GND electrode 54, and the circuit electrode 60 so as to enable the power supply electrode 52, the GND electrode 54, and the circuit electrode 60 to be connected to the small frame 76. In addition, at proper positions in the large frame 72 and the small frame 76, pilot holes 74 and 78 are formed, respectively.
Thereafter, pressing is performed on the small frame 76. Specifically, as illustrated in Fig. 9, the leg 79 disposed at the front end side of the antenna 1 is pressed upward so that the radiation electrode 38 and the upper conductor portion 32 are disposed above the connection portion 36, and more particularly, the intermediate connection portion 36c. This is because the upper connection portion 36a is formed upward from the intermediate connection portion 36c. In addition, by using a mold of the press, the oblique side 32a and the like are formed, and the convex portions 62 of the power supply electrode 52, the GND electrode 54, and the circuit electrode 60 are formed.
When the leg 79 disposed at the rear end side of the antenna 1 is pressed downward, the lower connection portion 36b is formed downward from the intermediate connection portion 36c so that the lower conductor portion 34 can be disposed below the intermediate connection portion 36c. In addition, the oblique portion 34 is also formed. In addition, corresponding portions of the connector 44, the power supply electrode 52, the GND electrode 54, and the circuit electrode 60 are formed downward. Additionally, as illustrated in Fig. 10, the corresponding portions of the power supply electrode 52 and the GND electrode 54 are formed to protrude downward, simultaneously, the convex portion 64 is formed at the circuit electrode 60, and the convex portion 42 is formed at the lower conductor portion 34.
The small frame 76 is disposed inside a mold after performing the pressing. Specifically, two molds 2 having a Π-shaped cross-section in the width direction of the base body 2 are prepared and disposed at upper and lower sides of the small frame 76 so that openings of the two molds face each other with the small frame 76 interposed therebetween. Accordingly, the radiation conductor 31 and the wiring conductor 50 are disposed inside the molds, and portions of the small frame 76 around the conductors and the leg 79 are disposed outside the molds.
Here, an upper surface of the intermediate connection portion 36c comes in contact with a vicinity of the opening of the mold (movable side) disposed above the small frame 76. On the contrary, a lower surface thereof is disposed inside a vicinity of the opening of the mold (fixed side) disposed below the small frame 76.
Next, a resin is injected upward from the fixed side mold. Accordingly, the base body 2 in the shape of a substantially rectangular pipe is formed along with the concave portion 16 (see Fig. 11), and portions of the radiation conductor 31 and the wiring conductor 50 are buried in the base body 2. Here, a reference numeral 24 in Figs. 4 and 6 denotes an injection hole of the aforementioned resin.
More specifically, as illustrated in Figs. 2 and 3, only a top portion of the upper conductor portion 32 of the radiation conductor 31 is exposed, and the oblique sides 32a and 32a are buried in the base body 2 to be maintained in the base body 2 so as not to be exposed.
In addition, upper surfaces of the upper connection portion 36a and the intermediate connection portion 36a of the connection portion 36 are exposed. On the contrary, the lower surface of the intermediate connection portion 36a is not exposed (Figs. 2 and 4). This is because the lower surface is disposed inside the vicinity of the opening of the mold and engaged with the stepped portion 12.
As illustrated in Fig. 4, only a bottom portion of the lower conductor portion 34 is exposed, and the oblique sides 34a and 34a are buried in the base body 2 and not exposed. In addition, the lower connection portion 36b of the connection portion 36 is not exposed and maintained in the base body 2 similarly to the oblique portion 34a. Portions of wiring conductor 50 excluding the convex portions 62 and 64 and the protruding portions of the power supply electrode 52 and the GND electrode 54 are buried in the base body 2 and not exposed (see Figs. 3 and 5).
Next, the base body 2 into which the radiation conductor 31 and the wiring conductor 50 are insert-molded, the aforementioned large frame 74, and the small frame 76 are cut. Specifically, as illustrated in Fig. 12, a lower mold (die) 86 is disposed below the small frame 76, and the die 86 is attached to the side surface 10. In addition, an upper mold (punch) 88 is disposed above the small frame 76. Here, an edge of the punch 88 comes in contact with the stepped portion 12, and the edge of the punch 88 is disposed inward from an edge of the die 86. The punch 88 cuts the intermediate connection portion 36c from the small frame 76 disposed outside the stepped portion 12.
The punch 88 and the die 86 simultaneously cut the power supply electrode 52, the GND electrode 54, and the circuit electrode 60 from the small frame 76 and cut the radiation electrode 38 and the GND electrode 54 from the leg 79 and 79, respectively. Thereafter, when the matching circuit 80 or the insulation substrate 82 of the tuning circuit is mounted on the concave portion 16, the antenna 1 is completed.
Meanwhile, the aforementioned base body 2 may have a plurality of holes.
For example, a plurality of holes may be formed between the top surface 4 and the bottom surface 6 of the base body 2. Since a linear expansion coefficient of the radiation conductor 31 or the wiring conductor 50 that is made of metal is different from that of the base body 2 made of resin, a deformation due to thermal stress may occur in the antenna 1. However, when the aforementioned holes are provided, as compared with an antenna without holes, a degree of the deformation can be controlled. In addition, a mass of the resin is reduced, so that the lightweight antenna 1 can be implemented. As a result, for example, during a drop test, the antenna 1 could withstand drop impact. This result contributes to a reliability improvement of the antenna 1.
As described above, in the antenna 1 according to the embodiment, the electrical component 84 in the chip shape is not directly mounted on the base body 2 but mounted on the insulation substrate 82. Therefore, as compared with a case where the electrical component 84 is directly mounted on the base body 2, high density packaging of the electrical component 84 is possible.
In addition, the insulation substrate 82 having the electrical component 84 is not mounted on the motherboard 90 but mounted on the base body 2. Therefore, as compared with a case where the insulation substrate 82 is mounted on the motherboard 90, the motherboard 90 requires a smaller space.
In addition, when the antenna 1 has the electrical component 84 for matching between the power supply wire of the motherboard 90 and the radiation conductor 31, as compared with a case without the electrical component 84, the antenna 1 can be easily adjusted, and this improves convenience of the antenna 1.
In addition, when the base body 2 is provided with the concave portion 16 and the concave portion 16 is configured such that the electrical component 84 is substantially at the same height as or lower than the top surface 4 of the base body 2, a top portion of the electrical component 84 does not protrudes from the top surface 4. As a result, the antenna 1 can be implemented to have a lower height.
In addition, when the wiring conductor 50 made of metal is insert-molded into the base body 2 made of resin, the wiring conductor 50 cannot be easily separated from the base body 2. Here, when the wiring conductor 50 is insert-molded into the base body 2, the wiring conductor 50 cannot be formed in a very small pattern. However, as described above, the electrical component 84 is mounted on the insulation substrate 82. Accordingly, although the wiring conductor 50 is insert-molded into the base body 2, high density packaging of the electrical component 84 is possible.
In addition, when the wiring conductor 50 has the convex portion 62 that is exposed from the base body 2 and connected to the terminal of the insulation substrate 82 with the solder, a joint area between the convex portion 62 and the solder increases, and the solder extends to surround the convex portion 62, so that joint strength between the convex portion 62 and the solder can be increased. In addition, without using a solder register for the base body, connection between the wiring conductor 50 and the insulation substrate 82 is possible.
In addition, when the convex portion 62 is formed by performing the drawing process, the convex portion 62 can be solidly formed.
In addition, when the conductor pattern 30 made of metal which includes the radiation conductor 31 in addition to the wiring conductor 50 is inserted-molded into the base body 2, the conductor pattern 30 cannot be easily separated from the base body 2, and this enhances reliability of the antenna 1.
When the conductor pattern 30 is insert-molded into the base body 2, the conductor pattern 30 is buried in the base body 2, and the bottom surface 6 of the base body 2 becomes flat. Here, when impact is exerted on the motherboard 90, bending occurs in the board 90, and the base body 2 may be easily separated from the board 90. However, the conductor pattern 30 according to the embodiment has the convex portions 42 and 64, and the convex portions 42 and 64 are exposed from the base body 2 and connected to the wire of the board 90 with solder.
Therefore, as compared with a case the bottom surface of the base body is simply flat, a joint area between the convex portions 42 and 64 and the solder increases, and the solder extends to surround the convex portions 42 and 64. Therefore, joint strength between the convex portions 42 and 64 and the solder is increased, and the base body 2 can be securely fixed to the board 90. In addition, when the convex portions 42 and 64 are formed by performing the drawing process, the convex portions 42 and 64 are solidly formed. Accordingly, it is easy to connect the conductor pattern 30 to the board 90, and there is no need to provide a solder register or the like to the board 90.
In addition, when the convex portions 42 and 64 are disposed at the both end portions of the base body 2 in the longitudinal direction, a gap between the substantially center portion of the base body 2 in the longitudinal direction and the board 90 occurs. Specifically, even when bending occurs in the board 90, the substantially center portion of the base body 2 cannot easily contact to the board 90. In other words, impact of the base body 2 on the board 90 hardly occurs. Therefore, the base body 2 can be fixed to the board 90 more securely. As a result, during a drop test, the antenna 1 could withstand drop impact. This result contributes to a reliability improvement of the antenna 1.
In addition, when the convex portions 42 and 64 are formed at the both ends of the base body 2 in the longitudinal direction, a gap between the substantially center portion of the base body 2 and the board 90 occurs. In addition, when the longitudinal axes of the convex portions 42 and 64 are perpendicular to the longitudinal axis of the base body 2, the base body 2 can be supported with respect to the board 90 more stably.
In addition, since the convex portions 42 and 64 are exposed from the base body, a size of each convex portion is limited. As described above, although the sizes of the convex portions 42 and 64 are limited, when three or more convex portions 42 and 64 are formed, joint strength between the convex portions 42 and 64 and the solder can be guaranteed.
In addition, the boundary portion between the radiation conductor 31 and the wiring conductor 50 is divided into the two branches, and a connection point (the connector 44) with the wiring conductor 50 is disposed on the central axis of the spiral. However, when the installation portion 46 is provided, the size of the convex portion 42 formed on the installation portion 46 is not small.
In addition, since the portions of the radiation conductor 31 are buried in the base body 2, as compared with a case where the radiation conductor 31 is formed on the surface of the base body 2, the radiation conductor 31 can be securely maintained in the base body 2. As a result, the radiation conductor 31 cannot be easily separated from the base body 2, the spiral pitch of the radiation conductor 31 can be accurately maintained.
In addition, when the radiation conductor 31 is insert-molded into the base body 2, the portions of the radiation conductor 31 can be easily buried in the base body 2. In addition, when oblique sides of which normal lines are substantially perpendicular, from among the 8 sides of the radiation conductor 31, that is, the aforementioned oblique sides 32a and 34a are buried in the base body 2 in the shape of a substantially rectangular pipe, separation of the radiation conductor 31 from the base body 2 can be prevented.
In addition, the radiation conductor 31 is formed integrally with the lower conductor portion 34, the upper conductor portion 32, and the connection portion 36. Therefore, the radiation conductor 31 can be formed by using a single metal plate. Accordingly, as compared with a case where an upper portion and a lower portion of a radiation conductor are separately provided, the number of components can be reduced, and the strength thereof can be increased.
In addition, when the radiation conductor 31 is formed in the spiral shape, the number of components can further be reduced.
In addition, from a top view or a bottom view of the antenna 1, the lower and upper conductor portions 34 and 32 do not overlap, and the connection portion 36 has the intermediate connection portion 36c. The intermediate connection portion 36c extends in the arrangement direction of the lower and upper conductor portions 34 and 32 and serves as a branch connection from which the lower and upper conductor portions 34 and 32 are divided. Therefore, the radiation conductor 31 can be formed in the spiral shape by using the single metal plate.
In addition, when the lower and upper connector portions 34 and 32 are formed in substantially parallel to each other, in the base body 2 with the limited size, as compared with a case where the lower and upper conductor portions 34 and 32 are alternately arranged, the length of the radiation conductor 31 can be maximized.
In addition, when outer shapes of the lower and upper conductor portions 34 and 32 are formed of the single metal plate, and the lower conductor portion 34 is pressed downward, the lower connection portion 36b is formed downward from the intermediate connection portion 36c, so that the lower conductor portion 34 can be disposed below the intermediate connection portion 36c. When the upper conductor portion 32 is pressed upward, with respect to a point at which the upper connection portion 36a is formed upward from the intermediate connection portion 36c, the upper conductor portion 32 is disposed above the intermediate connection portion 36c. Accordingly, the radiation conductor 31 in the spiral shape can be easily formed.
In addition, the connection portion 36 is maintained to be engaged with the stepped portion 12 formed at the side surface 10 of the base body 2, that is, to surround the stepped portion 12. Therefore, the radiation conductor 31 does not protrude from the side surface 10 of the base body 2 and thus does not affect the manufacturing efficiency, so that a desirable outer appearance can be formed.
In addition, when the area of the bottom surface 6 of the base body 2 including the radiation conductor 31 is larger than that of the top surface 4, the base body 2 can be stably mounted on the board 90.
In addition, when the radiation conductor 31 and the wiring conductor 50 are formed by punching and pressing the single metal thin plate 70, the conductors 31 and 50 can be formed to be connected to the small frame 76. In addition, the radiation conductor 31 and the wiring conductor 50 are insert-molded into the base body 2. Here, the lower surface of the intermediate connection portion 36c is engaged with the stepped portion 12. In a case where the radiation conductor 31 and the wiring conductor 50 are separated from the small frame 76, the punch 88 is disposed at the stepped portion 12, the intermediate connection portion 36c is disposed between the stepped portion 12 and the punch 88, and the die 86 is disposed at the base body 2 to cut the intermediate connection portion 36c from the small frame 76. Accordingly, the connection portion 36c does not protrude from the side surface 10 of the base body 2.
In addition, the aforementioned radiation electrode 38 has a larger area than the upper conductor portion 32, and a portion on which a strong electric field is exerted has a larger area. Therefore, a radiation efficiency of radio waves can be increased, and reception of radio waves can be increased due to transception characteristics.
In addition, when the antenna 1 is provided to a mobile device, the antenna 1 is disposed at an outer surface of a housing of the mobile device. Therefore, a whip antenna that has to be extended to be used is not needed. Accordingly, a smaller or thinner mobile device can be easily implemented.
In addition, the radiation conductor 31 according to the embodiment is spiral, that is, helical. However, the shape thereof is not limited thereto, and for example, a meander shape can be employed.
In addition, the antenna 1 according to the embodiment may receive other signal waves in addition to the digital terrestrial television broadcasting and be included in a personal digital assistant (PDA) or a notebook.
In addition, in any case described above, high density packaging of the electrical component can be obtained.
It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims of the equivalents thereof.

Claims

An antenna device comprising:
a base body (2) mounted on a circuit board (90);

a wiring conductor (50) to which power is supplied, and a radiation conductor (31) which is connected to the wiring conductor (50) to radiate radio waves, each of which is provided on the base body (2);

an insulation substrate (82) mounted on the base body (2); and

an electrical component (84) which is mounted on the insulation substrate (82) in a chip shape to be electrically connected to the wiring conductor (50).
The antenna device according to claim 1,
wherein the base body (2) has a stepped portion formed from a top surface (4) of the base body (2) toward the circuit board (90) to form a concave portion (16) in which the insulation substrate (82) is mounted, and
wherein the concave portion (16) is configured such that the electrical component (84) is substantially at the same height as or lower than the top surface (4).
The antenna device according to claim 1 or 2, wherein the base body (2) is made of resin, and the wiring conductor (50) is made of metal to be formed integrally with the base body (2).
The antenna device according to claim 3, wherein the wiring conductor (50) has a convex portion (62) which is exposed from the base body (2) and connected to a terminal of the insulation substrate (82) with solder.
The antenna device according to claim 4, wherein the convex portion (62) is formed by deforming the wiring conductor (50) in a thickness direction.
The antenna device according to any one of claims 3 to 5, wherein the base body (2) has a plurality of holes (24).