JP2002252516A - Chip antenna and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip antenna having a simple structure in which the antenna characteristics can be changed as outside dimensions and the height place of an antenna conductor are left as they are kept constant. SOLUTION: The chip antenna is formed in the structure in which the antenna conductor is buried by a dielectric chip 20 composed of the first dielectric section 21 positioning the antenna conductor 10 in fixed height, and the second dielectric section 22 covering the antenna conductor and being mounted on the upper section of the first dielectric section and space sections such as grooves 23 are formed particularly on the underside side (a surface not brought into contact with the antenna conductor) of the first dielectric section. The antenna characteristics are changed as the outside dimensions of the chip antenna and the height place of the antenna conductor are left as they are kept constant by altering the sizes of the grooves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip antenna having a structure in which an antenna conductor is embedded in a dielectric chip or a structure in which the antenna conductor is laminated, and a method of manufacturing the same.

[0002]

[Related Background Art] Recently, a chip antenna having a structure in which an antenna conductor is embedded in a dielectric chip has been used as a small antenna used for a cellular phone, a portable information terminal, a wireless LAN (local area network) device, and the like. Is attracting attention. Such a chip antenna has an advantage that the whole shape can be reduced as compared with a conventional general whip antenna because the antenna conductor (antenna element) is meandering. Used to be implemented.

[0003]

The antenna characteristics of such a chip antenna change under the influence of a printed circuit board on which the chip antenna is mounted.
For this reason, even if the antennas are used in the same frequency band, various types of products are required according to the mounting situation. Conventionally, such a demand has been met by changing the antenna conductor pattern and the dielectric material. However, it is undeniable that this requires a great deal of labor and effort.

The present invention has been made in view of such circumstances, and has as its object to provide chip antennas having various characteristics more easily.

[0005]

In order to achieve the above-mentioned object, a chip antenna according to the present invention has a structure in which an antenna conductor is embedded or laminated in a dielectric chip. , A space for forming an air layer, or a space for accommodating another dielectric.

Further, in the chip antenna according to the present invention, a dielectric chip having an antenna conductor embedded therein is provided by a first dielectric portion for positioning the antenna conductor at a predetermined height, and the first dielectric portion covering the antenna conductor. It is characterized in that it has a structure including a second dielectric portion provided above the dielectric portion, and a space portion provided on the lower surface side of the first dielectric portion and forming an air layer.

[0007] Preferably, the space portion is formed of a groove provided on a surface not in contact with the antenna conductor, and the groove has a shape in which the thickness of the dielectric chip is changed. Further, in the method of manufacturing a chip antenna according to the present invention, the dielectric chip is formed by removably fitting a nest of a predetermined shape in a formation portion of the space portion in a die for forming a dielectric chip, further comprising: It is characterized in that a plurality of types of chip antennas are manufactured by exchanging the nest.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a chip antenna according to an embodiment of the present invention will be described with reference to the drawings. [First Embodiment] FIG. 1 is a perspective view showing a schematic configuration of a chip antenna according to this embodiment. This chip antenna is basically an antenna conductor 1 having an antenna element 11 having a pattern shape meandering in a meandering shape, for example.
0 is embedded in the dielectric chip 20 having a substantially rectangular parallelepiped shape,
An electrode terminal portion 12 connected to the antenna element 11 of the antenna conductor 10 has a structure derived from an end of the dielectric chip 20.

Incidentally, the antenna conductor 10 is formed by patterning a conductor plate made of, for example, a copper alloy by punching, etching, or the like, and the meandering antenna element 1 is formed.
It has a shape in which the electrode terminal 12 is connected to one end. Specifically, the antenna element 11 in the antenna conductor 10 is formed by patterning a conductor plate having a thickness of, for example, 0.12 mm, and turning a conductor having a conductor width of 0.2 mm, a meandering width of 3.2 mm, and a meandering pitch of 0.6 mm into five turns. Formed over the entire surface. The substantially rectangular chip antenna formed by embedding the antenna element 11 of the antenna conductor 10 with the dielectric chip 20 is roughly 4 mm wide, 8 mm long, and 2.8 mm thick. Is achieved.

The chip antenna according to the present invention is characterized in that the dielectric chip 20 is provided below the antenna conductor 10 as shown in FIG. A first dielectric portion 21 for positioning the antenna element 11 at a predetermined height;
A second dielectric portion provided above the first dielectric portion so as to cover the antenna element; Further, it has a structure in which a groove 23 as a space for forming an air layer is formed on the lower surface side (the surface not in contact with the antenna conductor 10) of the first dielectric portion 21. The groove 23 realizes a shape in which the thickness of the first dielectric portion 21 and thus the thickness of the dielectric chip 20 are changed.

Particularly, in this embodiment, the antenna conductor 1 is maintained while keeping the whole shape of the chip antenna constant.
In order to set the height position of 0 high, the thickness t1 of the first dielectric portion 21 is set as large as 2.3 mm. Since the second dielectric layer 22 only plays a role in preventing the antenna conductor 10 from peeling off, the thickness t2 is set to 0.1.
It is formed as thin as 5 mm. And the antenna conductor 10
The total thickness (height) of the dielectric chip 20 including the thickness of the above is set to be 2.8 mm described above.

The groove 23 is formed so as to have a maximum groove depth of 1.8 mm, for example. Even in a portion thinned by the formation of the groove 23, a dielectric material having a minimum thickness of 0.5 mm is formed. Support the antenna conductor 10. The size (shape) of the groove 23
Is determined by the antenna specifications (antenna characteristics) required for the chip antenna as described later.

Incidentally, a chip antenna having such a structure is, for example, an injection mold 30 for insert molding as shown in FIG. 3 and a side of the injection mold 30 defining the lower surface side shape of the antenna chip. It is manufactured using a nest 31 having a predetermined shape to be fitted into the mold part. The nest 31 is provided with a projection 32 corresponding to the groove 23 to be formed on the lower surface side of the dielectric chip 20, and functions as a part of the injection mold 30 by being fitted in the injection mold 30 in advance. .

In the chip antenna having such a structure, after the above-described antenna conductor 10 is set in the injection mold 30 in which the nest 31 is previously fitted, a predetermined dielectric is placed in the injection mold 30. It is manufactured by the insert mold method of injecting. At this time, the dielectric chip 20 having the groove 23 formed on the lower surface thereof is formed by the protrusion 32 formed on the insert 31.

Thus, according to the chip antenna having the above-described structure, as shown in FIG. 2, the dielectric chip 20 in which the antenna conductor 10 is insert-molded is formed by the first dielectric portion 21 located below the antenna conductor 10. Thus, the height position of the antenna conductor 10 with respect to the ground plane of the printed wiring board on which the chip antenna is mounted is accurately defined. In addition, the groove 23 formed on the lower surface side of the dielectric chip 20, that is, the first dielectric 21, forms an air layer between the ground plane and the antenna conductor 10 in the printed wiring board.

As a result, if the size of the groove 23 and the size of the air layer formed by the groove 23 are changed according to the antenna specifications, the dielectric constant ε of the dielectric chip 20 as a whole is adjusted. This makes it possible to adjust the antenna characteristics. That is, it is possible to easily realize chip antennas having various specifications (antenna characteristics). This advantage is remarkable in an antenna of a type in which the shape of the antenna conductor 10 is difficult to change and thus the characteristic adjustment is difficult, that is, a chip antenna in which the antenna conductor 10 is manufactured by pressing a metal plate.

In the antenna of this embodiment, since the first dielectric portion 21 is thickened, the height of the antenna conductor 10 can be set sufficiently high to increase the antenna gain.
Further, since the adjustment range of the groove depth of the groove 23 can be widened, the resonance frequency and the frequency band can be adjusted over a wide range. Further, since the antenna element 11 is covered with the second dielectric portion 22, the antenna element is hardly peeled off as in the case where the antenna element is formed on the upper surface of the dielectric chip made of ceramic, and the structure is stable. It is possible to realize a strong chip antenna.

Therefore, even when chip antennas of various specifications are produced in small quantities and in many types, for example, the projections 32
By preparing a plurality of nests 31 having different sizes according to antenna specifications and selectively using these nests 31, chip antennas conforming to various specifications can be easily manufactured. Becomes In other words, it is possible to cope with various antenna specifications only by preparing the nest 31 corresponding to the antenna specifications without changing the main body of the injection mold 30. In particular, without changing the overall shape (external dimensions) of the chip antenna itself and while setting the height position of the antenna conductor 10 sufficiently high,
Since the resonance frequency and the frequency band with respect to the antenna conductor 10 can be adjusted by the size of the groove 23, the practical advantage is great.

As described above, when the thickness of the second dielectric portion 22 on the upper side of the antenna conductor 10 is reduced and the thickness of the first dielectric portion 21 on the lower side of the antenna conductor 10 is increased, In this case, when the dielectric (resin) is injected into the injection molding die 30, the wraparound of the dielectric tends to be uneven. However, in the chip antenna according to the present invention, in order to form the groove 23 in the first dielectric portion 21 on the lower surface side of the antenna conductor 10, a partially thin region is provided by the projection 32 of the nest 31 described above. Therefore, when a dielectric (resin) is injected into the injection mold 30, the dielectric wraps around the antenna conductor 10 in a well-balanced manner. As a result, effects such as effective injection molding of the dielectric chip 20 can be obtained. Note that the shape and size (area and depth) of the above-described groove 23 and the number thereof may be determined according to antenna specifications.

[Embodiment 2] As a space for forming an air layer, as shown in FIG.
May be a hole 24 that is opened in parallel in the horizontal direction. However, when such a hole 24 is provided, it is undeniable that the structure of the injection molding die 30 becomes complicated in terms of die cutting. Therefore, it is practically preferable to provide the groove 23 described above.

[Embodiment 3] As shown in FIG. 5, a plurality of grooves 23 are formed on the lower surface of the dielectric chip 20 in a grid pattern in a vertical and horizontal direction, so that the lower surface of the dielectric chip 20 is formed by a plurality of legs 25.
Can be formed. In this case, the leg portion 25 can be selectively removed later, and the space on the lower surface side of the dielectric chip 20 can be expanded, so that the antenna characteristics can be adjusted after the chip antenna is manufactured. Become. In addition, a groove 23 is formed in the manufactured chip antenna by cutting a lower surface of the dielectric chip 20 with a cutter, a drill, or the like, if necessary, so that the antenna characteristics can be adjusted.

[Embodiment 4] As shown in FIG. 6, another dielectric 26 is embedded in some (for example, one) of the plurality of grooves 23 provided in the dielectric chip 20. It is also possible to adjust the dielectric constant of the whole 20 and thereby adjust the antenna characteristics. In this case, the same dielectric material as that of the dielectric chip 20 may be used as the dielectric 26, or it is of course possible to use another kind of dielectric material. Also, by changing the type of the dielectric 26, the antenna characteristics can be adjusted.

[Embodiment 5] In each of the embodiments described above, the antenna conductor 10 is embedded in the dielectric chip 20, but the antenna conductor 10 is laminated on the surface of the dielectric chip 20. The same applies to those. 7A and 7B show an example thereof, wherein FIG. 7A is a plan view, FIG. 7B is a sectional view taken along the line AA, FIG.
(d) is a right side view.

This chip antenna is composed of a dielectric chip 20
The antenna element 11 is formed by attaching an antenna conductor 10 (patch antenna) made of a flat metal sheet or the like to the upper surface of the antenna element 11. Then, on the lower surface side of the dielectric chip 20,
Two spaces 23 each having a semicircular cross section are provided in parallel to form the space described above. In particular, in this embodiment, the base portion 13 of the electrode terminal portion 12 connected to the end portion of the antenna element 11 is curved downward in a quarter circle and embedded in the edge of the dielectric chip 20. Thus, the base 13 of the electrode terminal 12 is fixed to the dielectric chip 20. As a result, a structure is realized in which the root portion 13 of the electrode terminal portion 12 and further the antenna conductor 10 are difficult to peel off from the surface of the dielectric chip 20.

According to such a structure, the antenna conductor 1
Since “0” is provided on the upper surface of the dielectric chip 20, the height of the antenna conductor 10 with respect to the ground conductor of the circuit board on which the chip antenna is mounted can be made higher than when embedded in the dielectric chip 20. Antenna characteristics can be obtained. Further, the antenna characteristic can be easily adjusted by the groove 23 provided on the lower surface of the dielectric chip 20.

[Embodiment 6] The chip antenna having the structure shown in FIG. 8 has a side protruding piece 14 which is bent in an L-shape from four places on the side edge near the electrode terminal portion 12 of the flat antenna conductor 10. Are provided respectively. The distal end portions 15 bent further inward of these side protrusions 14 are shown in FIG.
(b) shows the dielectric chip 2 as shown in FIG.
The antenna conductor 10 is fixed on the upper surface of the dielectric chip 20 by embedding the antenna conductor 10 in the side of the zero.

[Embodiment 7] A chip antenna having a structure shown in FIGS. 9 (a) and 9 (b) showing a planar structure and a cross-sectional structure taken along the line CC thereof is shown in FIG.
Is provided in the vicinity of a concave portion 16 having a through hole at the bottom thereof,
It has a structure in which the recess 16 is embedded in the dielectric chip 20. The recess 16 is formed in the flat antenna conductor 10.
Is formed by pressing. When the antenna conductor 10 having such a concave portion 16 is set in a mold and a dielectric resin is injected, the concave portion 16 passes through the through hole.
Since the resin enters the inside, the recess 16 is embedded with the resin as shown in FIG. 9B. As a result, the antenna conductor 10 is firmly fixed to the upper surface of the dielectric chip 20.

[Embodiment 8] Further, a chip antenna having a plan configuration shown in FIGS. 10 (a) and 10 (b) and a cross section taken along a line DD thereof has an electrode terminal portion 12 of a flat antenna conductor 10.
Is provided in the vicinity of, and a part of the dielectric chip 20 is swelled through the through hole 17 as shown in FIG.
The antenna conductor 10 is firmly fixed between the bulging portion 27 and the surface of the dielectric chip 20. When forming the bulging portion 27, a recess (not shown) for bulging the resin may be provided in a portion of the mold where the through hole 17 is positioned.

[Embodiment 9] By the way, regarding the characteristics of the chip antenna, for example, as shown in FIG. 11, an adjustment element section connected to the antenna element 11 embedded in the dielectric chip 20 and projected to the side of the dielectric chip 20 The adjustment can also be performed by using 18. Specifically, on the side of the antenna element 11, there are provided adjusting element portions 18 each formed of a conductor piece protruding outward, particularly at a folded portion of the conductor, and the tip portions of these adjusting element portions 18 are The dielectric chip 20 has a structure protruding outward from a side portion over a predetermined length.

According to the chip antenna having such a structure, its antenna characteristics are exclusively defined by the antenna element 11 which forms the main part. However, since the adjusting element section 18 connected to the antenna element 11 is provided, the presence of the adjusting element section 18 is also an important factor for determining the antenna characteristics. However, since the adjustment element section 18 is positioned in the space protruding from the dielectric chip 20, the influence on the antenna characteristics is relatively small.

That is, the characteristics of the chip antenna having the above structure are mainly determined by the mounting height of the antenna element 11 from the ground conductor (the antenna element 11) on the printed circuit board when the chip antenna is mounted on the printed circuit board or the like. Dielectric chip 20 positioned at the bottom of
Thickness) and the dielectric chip 2 interposed between the ground conductor
It is almost determined by the dielectric constant ε of 0. At this time, the adjustment element section 18 basically includes the antenna element 1
Although it is positioned at the same height as 1, the effect on the antenna characteristics is relatively small because only an air layer (dielectric constant ε _O ) exists between itself and the ground plane.

However, since the adjusting element portion 18 is located in the external space protruding from the dielectric chip 20, it can be easily cut. If the length of the adjusting element portion 18 is cut to reduce the length, the capacitance formed between the adjusting element portion 18 and the ground plane is reduced, and the electrical length of the antenna is shortened. The resonance frequency at 11 can be increased.
Also, the adjusting element portion 18 protruding outside the dielectric chip 20
Is bent downward, the height of the adjustment element portion 18 with respect to the ground conductor (GND) changes.
(Capacitor) C formed between the capacitor 8 and the ground conductor
Changes. This capacitance C has a great influence on the antenna characteristics.

For example, if the adjusting element portion 18 is bent downward to approach the ground conductor, the influence on the antenna element 11 becomes strong, and the antenna element 11
, The resonance frequency becomes lower. Conversely, if the adjustment element portion 18 is bent upward and away from the ground conductor, the influence on the antenna element 11 is slightly reduced,
The resonance frequency of the antenna element 11 becomes slightly higher. As described above, the resonance frequency band of the antenna element 11 also changes with the cutting and bending of the adjustment element section 18. Therefore, by cutting or bending the adjustment element portion 18 protruding from the side of the dielectric chip 20, the resonance frequency and the frequency band can be adjusted.

Therefore, in the chip antenna having such an adjusting element section 18, if the above-mentioned groove 23 is provided on the lower surface of the dielectric chip 20 (first dielectric section 21) as described above, for example, The antenna characteristics roughly adjusted by the adjustment 23 can be finely adjusted by using the adjustment element section 18.

[Embodiment 10] In a chip antenna having a structure in which an antenna element 11 having an adjusting element portion 18 is provided on an upper surface of a dielectric chip 20 as shown in FIG. Groove 23 described above
Is provided, the antenna characteristic roughly adjusted by the groove 23 can be finely adjusted by using the adjustment element section 18. That is, even in chip antennas having various structures in which the antenna conductors 10 are fixed (laminated) on the upper surface of the dielectric chip 20, the grooves 23 forming the above-described space are provided on the lower surface of the dielectric chip 20, so that each of the above is provided. The same effects as in the embodiment can be obtained. In addition to the groove 23 having a semicircular cross section,
As described above, it is needless to say that the antenna characteristics can be adjusted by providing the space portions of various shapes.

In each of the above embodiments, the antenna conductor 10
As an example, the antenna element 11 made of a meandering meandering conductor (Embodiments 1 to 4) and the antenna element 11 formed with a flat patch antenna (Embodiments 5 to 8) are exemplified. There may be. Further, also regarding the place where the electrode terminal portion 12 is taken out,
Instead of taking out each of the two ends in the longitudinal direction of the dielectric chip 20, two electrode terminals 1
2 may be arranged and taken out. In addition, a structure in which the dielectric chip 20 is taken out from a corner or the like of the dielectric chip 20 is similarly applicable.

The dielectric chip 20, or the first and second
The second dielectric portions 21 and 22 each include a plurality of layers.
It may be something. Further about the dielectric chip 20
Is, for example, PPS (polyphenylene sulfide)
And BaO-Nd_TwoO_Three-TiO_Two-Bi _TwoO_ThreeCeramic powder
Resin / ceramic composite material with mixed powder or LC
A resin material such as P (liquid crystal polymer) can be used as appropriate.
You. The dielectric constant ε also depends on the antenna specifications.
However, for example, it is recommended to use those of [3.1] to [20].
You can do it. In addition, the present invention does not deviate from the gist.
Various modifications can be made within the scope.

[0038]

As described above, according to the present invention, since the space is provided in the dielectric chip, the antenna characteristics can be easily adjusted by utilizing the space. Therefore, even when various kinds of chip antennas with different antenna characteristics are manufactured in small quantities and in various types, merely changing the size of the space portion or putting another dielectric material in the space portion increases the external dimensions and height of the antenna conductor. While maintaining the antenna constant, it is possible to achieve a great effect in practical use, such as a simple implementation of a chip antenna satisfying various antenna specifications.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a chip antenna according to a first embodiment of the present invention.

FIG. 2 is a view showing a schematic sectional structure of the chip antenna shown in FIG. 1;

FIG. 3 is a diagram showing a manufacturing example of the chip antenna shown in FIG. 1;

FIG. 4 is a perspective view showing a schematic configuration of a chip antenna according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a schematic configuration of a chip antenna according to a third embodiment of the present invention.

FIG. 6 is a sectional view showing a schematic configuration of a chip antenna according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a schematic configuration of a chip antenna according to a fifth embodiment of the present invention and a structure for fixing an antenna conductor to an upper surface of a dielectric chip.

FIG. 8 is a diagram showing a schematic configuration of a chip antenna according to a sixth embodiment of the present invention and a structure for fixing an antenna conductor to an upper surface of a dielectric chip.

FIG. 9 is a diagram showing a schematic configuration of a chip antenna according to a seventh embodiment of the present invention and a structure for fixing an antenna conductor to an upper surface of a dielectric chip.

FIG. 10 is a diagram showing a schematic configuration of a chip antenna according to an eighth embodiment of the present invention and a structure for fixing an antenna conductor to an upper surface of a dielectric chip.

FIG. 11 is a perspective view showing a schematic configuration of a chip antenna according to a ninth embodiment of the present invention.

FIG. 12 is a perspective view showing a schematic configuration of a chip antenna according to a tenth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Antenna conductor 11 Antenna element 12 Electrode terminal part 13 Root part 14 Side protruding piece 16 Depressed part 17 Through hole 20 Dielectric chip 21 First dielectric part 22 Second dielectric part 23 Groove forming air layer ( (Space part) 30 injection molding die 31 nesting 32 projection

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masayuki Isawa 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. F-term (reference) 5J046 AA00 AA03 AB13 PA04 QA02

Claims (5)

[Claims] An antenna conductor and a dielectric chip in which the antenna conductor is embedded or laminated, wherein the dielectric chip has a space forming an air layer or a space in which another dielectric is accommodated. A chip antenna characterized by comprising a portion. 2. An antenna conductor, comprising: a dielectric chip in which the antenna conductor is embedded; wherein the dielectric chip includes a first dielectric portion that positions the antenna conductor at a predetermined height; A second dielectric portion provided to cover the first dielectric portion and provided above the first dielectric portion; and a space portion provided on the lower surface side of the first dielectric portion to form an air layer. And chip antenna. 3. The chip according to claim 1, wherein the space portion includes a groove provided on a surface that is not in contact with the antenna conductor, and the dielectric chip has a shape whose thickness is changed by the groove. antenna. 4. The method for manufacturing a chip antenna according to claim 1, wherein a nest having a predetermined shape is exchangeably fitted into a forming portion of the space portion in a die for forming a dielectric chip. Forming a dielectric chip by using the above method. 5. The method for manufacturing a chip antenna according to claim 4, wherein the nest is replaced to manufacture a plurality of types of chip antennas.