JP2016059035A - Chip antenna and antenna module using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip antenna and an antenna module that can achieve high performance as a chip antenna and suppress the thickness of an antenna module using the same.SOLUTION: There is prepared a rivet core formed of a magnetic body which has a flange portion and a barrel portion above the flange portion, and is provided with an opening having an opening face at only the bottom surface of the flange portion side. An electrical conduction wire is wound around the barrel portion of the rivet core, and the electrical conduction wire is drawn to the bottom surface of the rivet core. The drawn electrical conduction wire is connected to the electrode face of the rivet core bottom surface to achieve a compact low-back chip antenna. The board having an electrical component mounted thereon is covered by the chip antenna so that the electronic component is accommodated inside the opening, thereby achieving a compact low-back antenna module.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a chip-type antenna and an antenna module in which an electronic component such as an IC chip is combined.

Conventionally, a chip-type antenna has been produced by winding a conductive wire around the body of a convex magnetic rivet core. Then, an antenna module has been created by combining this chip antenna with electronic components such as an IC chip and a capacitor separately.

In recent years, in such an antenna module, there is an increasing demand for reduction in size and height, and Patent Document 1 discloses a substrate on which an electronic component 41 is mounted as shown in FIGS. 11 (a) and 11 (b). There is described an antenna module 44 in which 42 is housed inside a chip-type antenna 43 to reduce the overall size and height.

Japanese Patent No. 3649128

However, since the antenna module 44 is provided with a slit 48 for connecting the lead wire 47 to the electronic component 41 in the body portion 46 of the rivet core 45 to be used, the horizontal communication range of the antenna module 44 is measured. Then, as shown in FIG. 12, the direction with the slit 48 has a problem that the communication range becomes smaller, and the communication range is not uniform in all directions, resulting in an irregular shape (first problem).

Further, since the bottom of the rivet core 45 is cut out to enclose the electronic component 41 and the substrate 42, there is a problem that the volume of the magnetic body of the body portion 46 is reduced correspondingly and the antenna performance is reduced (first). Issue 2).

Accordingly, an object of the present invention is to provide a chip antenna that is small in size and low in profile, that suppresses a decrease in antenna performance and that has a uniform horizontal communication range, and an antenna module using the chip antenna.

Therefore, as a result of intensive studies to solve the above problems, the present inventors, as a result of adopting the following configuration, provide a chip antenna and an antenna module in which the horizontal communication range is evenly expanded while suppressing the thickness. I found out that

In a chip antenna comprising a columnar body and a rivet core made of a magnetic material formed from a flange extending in a plate shape from one end surface thereof, and a lead wire wound around the body, the chip antenna has a surface on the side of the flange By providing a chip antenna having an opening having only an open surface, the side surface and the upper surface of the body portion and the collar portion have no cutout leading to the opening or the like.

Furthermore, the rivet core can be enlarged as much as possible on the square installation surface by making the trunk portion and the flange portion into a chip antenna having a substantially square outer shape. In the present invention, the “outer shape” means the shape of the outermost contour line in the horizontal cross-sectional shape of the trunk or the collar.

Further, in the horizontal cross section of the body portion, the distance between the outer peripheral portion of the body portion and the inner periphery of the opening is a chip antenna so that the magnetic flux converged at the body portion of the chip antenna is horizontal. Spread uniformly in the direction.

Furthermore, the said hook part makes it a chip antenna which has a notch part in the one part, The conducting wire wound by the trunk | drum can be pulled out from a notch part to the back part of a buttocks part.

Furthermore, the conductive wire is formed into a chip antenna that passes the start and / or end of winding through the notch and extends to the back surface side of the rivet core, whereby the winding start and / or end of winding of the conductive wire is performed. The leader line does not jump out of the shape formed by the buttock.

Furthermore, when the notch is a chip antenna at the corner of the flange, a decrease in performance due to the notch can be reduced.

Furthermore, when the collar portion is a chip antenna having a positioning portion for determining the direction of the rivet core, the directionality of winding start, winding end, electrode position, etc. can be easily determined.

Furthermore, when the opening is a chip antenna having a substantially rectangular parallelepiped shape, an electronic component that is generally a rectangular parallelepiped can be easily accommodated. Note that the “opening” in the present invention means “a hollow portion hollowed out from the inside of the magnetic body”.

It consists of a substrate on which the electronic component is placed, a columnar body placed on the substrate, and a flange projecting in a plate shape from one end surface thereof, and is open only to the surface on the flange side. An antenna module comprising a chip antenna composed of a magnetic rivet core provided with an opening having a surface and a conducting wire wound around the body portion, and housing the electronic component inside the opening. As a result, the components necessary for the antenna module can be combined into one, and a compact antenna module with a reduced height and installation area can be obtained.

Furthermore, when the substrate has an antenna module having an outer shape substantially the same as the outer shape of the collar portion, the installation area of the antenna module can be minimized.

Furthermore, the conductive wire is an antenna module that extends to the back side of the rivet core by passing the winding start and / or winding end through the notch, so that the conductive wire protrudes outward from the antenna module. There is no longer to do.

Furthermore, the lead wire is an antenna module electrically connected to the core side electrode provided on the back surface of the rivet core at the winding start and / or winding end, thereby mounting the chip antenna portion on the substrate. Can be integrated.

Furthermore, since the conductive wire is an antenna module that is electrically connected to the substrate via the core-side electrode, it is not necessary to directly connect the conductive wire to the substrate.

  According to the present invention, there is an effect that the antenna module can be reduced in size and height by covering the electronic component with the chip antenna. Further, since the opening surface of the opening is only the bottom surface on the buttock side, the trunk portion has a shape without a cutout or a slit, so that the horizontal communication range can be made uniform.

The perspective view which shows the front side of the rivet core used for this invention. The perspective view which shows the back side of the rivet core used for this invention. Sectional drawing which shows the A-A 'cross section of the rivet core of Fig.1 (a). The perspective view which shows the chip antenna which concerns on this invention. The assembly perspective view which shows the antenna module which concerns on this invention. The perspective view which shows the antenna module which concerns on this invention. The assembly perspective view which shows the antenna module and cover which concern on this invention. The top view which shows the communication range of the chip antenna which concerns on this invention. Sectional drawing which shows the winding start of the rivet core without a notch in a collar part. Sectional drawing which shows the winding start of the rivet core which has a notch in a collar part. Sectional drawing which shows the antenna module which concerns on this invention. The perspective view which shows the antenna module of a well-known example. Sectional drawing which shows the B-B 'cross section of the antenna module of Fig.11 (a). The top view which shows the communication range of the chip antenna of a well-known example.

An embodiment for manufacturing a chip antenna and an antenna module using the chip antenna according to the present invention will be described below. Note that some drawings are expressed by changing or simplifying the size, shape, or the like so as not to affect the essence of the invention in order to emphasize a part or make it easy to explain.

First, a rivet core 1 made of a magnetic material shown in FIGS. 1A and 1B is prepared. The rivet core 1 is provided with a trunk portion 3 having a square outer shape above a flange portion 2 having a substantially square outer shape. Furthermore, an opening 6 having a horizontal cross section having an open surface 5 is provided only on the bottom surface 4 on the collar side, and a core side electrode 7 is provided on the bottom surface 4.

As shown in FIG. 2, the length of each part of the rivet core 1 is that the collar width c is 5.5 to 9.5 [mm], and the trunk width b is b = c−0.8 to 2 [mm]. The core thickness d is set to 0.7 to 4.0 [mm], the collar thickness f is set to 0.3 to 0.8 [mm], and the ratio A2 = b / c between the collar width c and the trunk width b is preferable. Is 0.8 <A2 <0.9, and the ratio A4 = f / d between the core thickness d and the collar thickness f is 0.18 ≦ A4 <0.45. If the collar width c is larger than the body width b by more than 2 [mm], the collar section 2 will be damaged due to insufficient strength when connecting an electrode surface and a conductive wire, which will be described later. On the contrary, if the difference between the collar width c and the body width b is less than 0.8 [mm], a space for winding the conductive wire around the rivet core 1 cannot be secured, and a necessary inductance cannot be obtained and the target chip is obtained. An antenna cannot be obtained. In the present invention, “opening width”, “body width”, and “gutter width” to be described later are the length of one side when the outer shape or the shape of the open surface is substantially square, The length of the diameter means the length of the diameter of a circle having the same area as the shape in the case of other shapes. In addition, the notation [mm] is a shorthand notation indicating that the unit of the numerical value or mathematical formula immediately before is mm.

In addition, the size of the opening may be at least a size that can accommodate at least one electronic component described later, but the opening width a is a = b−1 to 2 [mm], and the opening depth e is e. = D−0.5 [mm], preferably, the ratio A1 = a / b of the body width b to the opening width is 0.6 <A1 <0.8, the core thickness d and the opening depth The ratio A3 = e / d with e is set to satisfy 0.25 <A3 <0.75. If the opening width “a” and the opening depth “e” are too large, the body portion becomes thin, and the strength required for the steps described later cannot be obtained, which may cause damage. Furthermore, since the amount of magnetic material in the body 3 is reduced, the required antenna performance cannot be obtained. On the other hand, if it is too small, the antenna performance and strength are enhanced, but the electronic component cannot be accommodated inside the opening 6.

Here, when the distance (wall thickness) g between the outer peripheral portion and the inner peripheral portion is not constant in the cross section obtained by horizontally cutting the body portion, the amount of the magnetic material is biased. If an antenna is created using a rivet core in which the amount of magnetic material is biased, the distance that can be communicated in the horizontal direction will be biased. Therefore, it is preferable that the distance (wall thickness) g between the outer peripheral part of the body part and the inner peripheral part of the opening is equal in all of the openings.

It is preferable to provide a notch 9 only in the corner portion 8 of the flange portion 2. The cutout 9 may be of a size that can pass at least the conductor, but a square that reaches the boundary point 10 between the body 3 and the flange 2 at the corner 8. Is preferable. The notch reaching the boundary point 10 which is the base portion of the body portion 3 enables winding as described later.

An arbitrary number of the notches 9 can be provided in the flange portion 2, but preferably, three of the four corner portions 8 are provided. By setting it as three places, while being able to let both ends of a conducting wire pass to the bottom face side from another notch 9, the directivity arises in the collar part 2, and the up-and-down and right-and-left difference can be prevented at the time of manufacture.

  The material of the rivet core 1 may be a magnetic material such as ferrite (Ni—Zn, Mn—Zn), iron powder, compacted powder, Ni—Zn, and Mn—Zn. The rivet core 1 is obtained by press-molding such a powder material into the above shape and firing at 800 to 1000 ° C. The method of forming the rivet core is not shown in the figure, but the body part, the buttock part, and the opening are all press-molded at once. It is possible to select a method such as molding by bonding the molded and baked material.

  Next, as shown in FIG. 3, the conducting wire 11 is started to be wound along the trunk portion 3 and the flange portion 2 through the notch 9, and then the conducting wire 11 is wound around the trunk portion 3 in sequence. This winding method makes it possible to obtain a target number of windings without increasing the overall thickness of the rivet core. Furthermore, it is possible to suppress a decrease in antenna performance due to a decrease in the amount of magnetic material used for the rivet core by the opening. For the conductive wire, for example, copper coated with an insulating material such as urethane, vinyl, or polyimide can be used.

After the conducting wire 11 is wound around the trunk portion 3, both ends 12 thereof may be directly connected to a substrate described later, but preferably, the crimping is applied to the core side electrode 7 formed on the bottom surface 4. Electrical connection is made by soldering or other methods. The chip antenna 13 is completed by fixing the end 12 of the conducting wire 11 to the core-side electrode 7.

Next, an antenna module is manufactured using the chip antenna 13. As shown in FIG. 4, a substrate 15 on which an electronic component 14 such as an IC chip or a capacitor is placed is prepared. However, the electronic component 14 is disposed so that all of the electronic component 14 is accommodated inside the opening 6. At this time, a substrate-side electrode 16 is provided on the substrate 15 at a position corresponding to the core-side electrode 7 of the chip antenna 13. The chip antenna 13 is placed on the substrate so that the electronic component 14 is covered, and the substrate-side electrode 16 and the conductor 11 and / or the core-side electrode 7 are electrically connected by pressure bonding or soldering. And the chip antenna 13 and the substrate 15 are fixed. Thereby, it is not necessary to pull out the lead wire 11 from the chip antenna 13 and connect it to the substrate 15, and it is easy to electrically connect the lead wire 11 and the substrate 15. The antenna module 17 shown in FIG. 5 is completed by the above procedure.

  For mass production, it is preferable to cover the antenna module 17 shown in FIG. 6 with a cover 18 for product protection. The cover 18 is preferably made of a nonmagnetic material such as plastic or resin. The reason for using a non-magnetic material is that if a cover made of a magnetic material is used, the magnetic field for communication forms a closed magnetic circuit, and the communication distance is significantly shortened. The cover 18 may be shaped to cover the entire rivet core, or may be shaped to be placed on the body 3 (not shown).

  The effects of the chip antenna 13 of the present invention thus obtained and the antenna module 17 using the chip antenna 13 will be described. In general, the performance (X) of a chip antenna in which a conducting wire is wound around a magnetic core is based on the number of turns (N) and the volume of the magnetic body in which the conducting wire is wound (V, hereinafter referred to as “effective volume”). Evaluation is made by an evaluation formula (X = N × V × C) consisting of a value multiplied by a constant (C). Therefore, hereinafter, the level of the antenna performance is evaluated based on the number of turns N and / or the size of the effective volume V.

First, the effect that the open surface 5 is only the bottom surface 4 of the rivet core 1 will be described. In the antenna module 44 of Patent Document 1 shown in FIGS. 11A and 11B, a slit 48 leading to the opening 49 is provided in the body portion 46. Due to the slit 48, the outer shape of the body portion 46 is not a circle but a large depression.

In general, the communication range of the antenna module is drawn as a contour line according to the signal strength, but the closer the shape is to a circle, the better. As shown in FIG. 12, the horizontal communication range of the antenna module 17 has a concave shape with the slit 48, and the communication range is not stable depending on the direction. In addition, since the size of the slit can only be reduced to the size that the conductor can pass through at the minimum, as the antenna module is made smaller, the ratio of the slit to the trunk increases, and the above-mentioned influence on the communication range is not affected. growing. If the communication range is not stable, even if the antenna module 17 is intended to be placed within the communication range, communication signals cannot be transmitted / received correctly, or communication can be performed only in a specific situation. Furthermore, the effective volume V decreases due to the presence of slits in the body.

However, the horizontal communication range of the antenna module 17 of the present invention shown in FIG. 7 has a square shape with rounded corners closer to the antenna, and approaches a clean circle as the distance from the antenna increases, and is stable. As a result, signals can be transmitted and received stably. In addition, since the effective volume V increases as much as there is no slit, the reduction of the effective volume V due to the opening can be minimized. Therefore, the antenna module 17 of the present invention can minimize the deterioration of the antenna performance due to the provision of the opening.

Next, the effect of the notch provided in the collar will be described. 8 and 9 are sectional views of the periphery of the corner portion 8 of the chip antenna 13 in which the conducting wire 11 is wound around the trunk portion 3. The conductive wires in these two figures are wound by repeating 11a → the back of the drawing → 11b → the front of the drawing → 11c → the back of the drawing → 11d →. In addition, the chip antenna 13 shown in FIGS. 8 and 9 has the same body width b, collar width c, core thickness d, collar thickness f, wire diameter, etc., except for the presence or absence of the notch 9. .

  When using the rivet core 1 having the notched flange 2, as shown in FIG. 8, the conductor 11 is introduced over the flange 2 to start winding. In this method, since the introduction portion 11a of the conducting wire 11 is on the flange portion 2 and the introducing portion 11a obstructs the conducting wire 11, the number of windings (the number of turns) of the conducting wire is reduced to seven.

However, when using the rivet core 1 having the flange 2 having the notch 9, as shown in FIG. 9, the lead wire 11 is introduced from the notch 9 and starts to be wound. Since 11a does not exist and does not interfere with the wound conductive wire 11, the number of windings of the conductive wire is 9, which can be increased twice as compared with the case where there is no notch 9. The effect of increasing the number of turns by adopting this winding method is that the number of turns cannot be increased due to a physical restriction that the collar width c or the core thickness d is small, for example, the number N of turns is 30 or less. In the small and low-profile antenna as in the invention, it appears more prominently.

In the case where the number of windings N is 30 times or less, the effect that can be increased twice will be described using the evaluation formula. When the winding method according to the present invention is employed, the number of turns can be increased while keeping the effective volume V constant, and therefore the increase rate of the number of turns N becomes the improvement rate of the antenna performance X as it is. For example, as shown in FIGS. 8 and 9, when N increases from 7 times to 9 times, the antenna performance X is improved by about 28.6% from 9 ÷ 7≈1.2857. Even when the winding number N is increased from 28 to 30 times, this is an improvement of about 7.1% from 30 ÷ 28≈1.0714. Therefore, when the number of turns N is small and the number of turns can be increased twice, the antenna performance X can be improved by about 7 to 29%, and the rate of improvement becomes larger when the number of turns is small. That's what it means.

If the same performance improvement rate is to be obtained by increasing the effective volume, the body width and the core thickness must be increased equally, so that the installation area on the product and the thickness of the entire chip antenna are about 29 at the maximum. As a result, it is difficult to reduce the size of a product to be mounted with a chip antenna or an antenna module. Therefore, drawing out the conducting wire from the notch and starting winding as in the present invention greatly improves the antenna performance.

Next, the location and influence of the notch will be described. In the rivet core, the trunk portion is largely related to the convergence performance of the magnetic flux directly connected to the antenna performance. The flange portion relates to the direction in which the magnetic flux is released, but does not affect the magnetic flux convergence performance. Therefore, if a notch or a slit is provided in the trunk as in Patent Document 1, it greatly affects the communication range as described above. However, by providing a notch only in the collar as in the present invention, the antenna The performance can be prevented from being affected.

Further, by providing a notch in the collar part, the lead wire can be fixed to the back side of the collar part without protruding the winding start and / or winding end outside the square substantially matching the contour line of the collar part.

Next, the effect of manufacturing an antenna module including a substrate, an electronic component mounted thereon, and a chip antenna placed on the substrate will be described. When manufacturing an antenna module, it is composed of an antenna unit such as a coil and an inductor for transmitting and receiving radio waves and an electronic component such as an IC chip and a capacitor for processing received radio waves. Therefore, a large installation area is required. However, as in the present invention shown in FIG. 5, the electronic component is covered with a chip antenna so that the installation area required for the antenna module according to the present invention is only one chip antenna, and the entire antenna module is provided. As a result, the installation area can be reduced, contributing to the downsizing of products equipped with chip antennas.

However, at this time, as in Patent Document 1 shown in FIG. 11, if the size of the substrate 42 on which the electronic component is placed becomes smaller than the opening 49, the substrate 42 is accommodated inside the opening 49. As can be seen, it is necessary to increase the core thickness d0 of the rivet core by the thickness of the substrate 42, which makes it difficult to reduce the thickness. Further, in order to connect the conductive wire 47 and the substrate 42, it is necessary to provide a slit 48 in the body portion 46 of the rivet core 45, or the connection between the antenna module 44 and a substrate (not shown) on which the antenna module 44 is placed is complicated. It becomes. Furthermore, since it is necessary to make the opening depth e deeper by the amount of the substrate to be included, the effective volume V is reduced by that amount, and the antenna performance X is lowered. However, in the antenna module 17 of the present invention shown in FIG. 5, since the substrate 15 has an outer shape substantially the same as the outer shape of the flange 3, the body 3 is connected when the conductor 11 is connected to the substrate 15. There is no need to provide a slit, and as shown in FIG. 10, the antenna module 17 and the substrate 15 on which the antenna module 17 is placed can be easily connected using the solder 20. Furthermore, since the opening depth e may be only the height of the electronic component mounted on the substrate, the reduction of the effective volume V can be minimized, and the degradation of the antenna performance X can be minimized. Can do.

As described above, the details of the present invention have been described with reference to examples. However, the present invention is shown only as specific embodiments of the present invention, and the effects of the invention are remarkably impaired based on the technical idea. It should be understood that some of the embodiments can be modified and implemented to a lesser extent.

For example, (1) the outer shape of the trunk and the buttock and the horizontal cross section of the opening can be a polygon other than a square or a circle. (2) The number of mounting electrodes can be three or four instead of two. In particular, if the mounting electrodes are arranged at all four corners of a square substrate, the antenna module is automatically balanced by the surface tension of the melted solder when the antenna module is mounted on the product substrate by soldering. The effect of suppressing the displacement of the mounting position can be obtained. Further, by changing the shape of the core from a rivet type in which the flange portion is present only at one end of the trunk portion to a drum shape in which both ends of the trunk portion are present, the chip antenna of the present invention is used as an inductor, and an antenna module Other modules can also be manufactured.

The present invention can be widely used in the field of near field communication antennas such as Felica antennas and RFID tag antennas regardless of frequency bands.

1: rivet core 2: flange part 3: trunk part 4: bottom face 5: open face 6: opening 7: core side electrode 8: corner part 9: notch 10: boundary point 11: conductor 11a: lead-in part 11b, 11c, 11d, 11e, 11f, 11g, 11h, 11i, 11j, 11k, 11l, 11m, 11n, 11o, 11p, 11q: conducting wire 12: end 13: chip antenna 14: electronic component 15: substrate 16: substrate side electrode 17 : Antenna module 18: Cover 19: Communication range 20: Solder 21: Mounting electrode 22: Mounting substrate 41: Electronic component 42: Substrate 43: Chip antenna 44: Antenna module 45: Rivet core 46: Body 47: Conductor 48 : Slit 49: opening a: opening width b: trunk width c: collar width d, d0: core thickness e: opening depth f: collar thickness g: wall thickness

Claims (14)

In a chip antenna consisting of a columnar body and a rivet core made of a magnetic material composed of a flange projecting in a plate shape from one end face thereof, and a conductive wire wound around the body,
A chip antenna, wherein an opening having an open surface is provided only on a surface on the flange side.   2. The chip antenna according to claim 1, wherein the distance between the outer periphery of the body and the inner periphery of the opening is uniform in a horizontal section of the body. The chip antenna according to claim 1, wherein the trunk portion and the flange portion have a substantially square outer shape. The chip antenna according to claim 1 or 3, wherein the flange has a notch in a part thereof. 5. The chip antenna according to claim 4, wherein the conductive wire extends through a notch portion of the winding start and / or winding end to the back side of the rivet core.   The chip antenna according to claim 4 or 5, wherein the notch is at a corner of the flange.   The chip antenna according to claim 1, wherein the flange portion has a positioning portion for determining a direction of the rivet core. The chip antenna according to claim 1, wherein the opening is a substantially rectangular parallelepiped. It consists of a substrate on which the electronic component is placed, a columnar body placed on the substrate, and a flange projecting in a plate shape from one end surface thereof, and is open only to the surface on the flange side. An antenna module comprising a magnetic rivet core provided with an opening having a surface and a chip antenna made of a conductive wire wound around the body, and the electronic component is housed in the opening. The antenna module according to claim 9, wherein the substrate has an outer shape substantially the same as an outer shape of the collar portion. The antenna module according to claim 9 or 10, wherein the flange has a notch in a part thereof. The antenna module according to claim 11, wherein the conductive wire extends to the back side of the rivet core by passing the winding start and / or winding end through the notch. The antenna module according to claim 9, wherein the conductive wire is electrically connected at a winding start and / or winding end to a core-side electrode provided on a back surface of the rivet core. The antenna module according to claim 13, wherein the conductive wire is electrically connected to the substrate via the core-side electrode.

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