HK40022408B - Lc resonance antenna - Google Patents

Description

LC resonance antenna

Cross reference to related applications

This application is based on the priority claim of japanese patent application No. 2017-212896 and is incorporated by reference into the description of the specification of this application.

Technical Field

The present invention relates to an LC resonance antenna for transmitting and receiving radio waves.

Background

Various small antennas have been provided, which are provided on electronic instruments, articles, and the like. As such an antenna, for example, patent document 1 discloses an LC resonance antenna incorporated in an information carrier that performs contactless communication with a reader/writer.

The LC resonance antenna has: a sheet-like insulating substrate; a gain coil (so-called inductor) formed on a surface of the insulating substrate (hereinafter referred to as "substrate surface"); a capacitor connected to the gain coil.

The gain coil is formed in a region around the outer periphery of the insulating substrate so as to be wound spirally from the outer periphery toward the inner periphery. The region surrounded by the booster coil is a non-formation region where the booster coil is not formed.

The capacitor has: a surface-side conductor film formed on the surface of the substrate; a back side conductive film formed on the back side of the substrate (hereinafter referred to as "substrate back side").

The surface-side conductor film is formed in the non-formation region of the substrate surface and connected to one end of the gain coil on the inner peripheral side. The back-side conductor film is disposed in a region of the back surface of the substrate corresponding to the non-formation region.

In this way, in the LC resonance antenna, the capacitor is provided on the inner peripheral side of the booster coil, that is, in the non-formation region.

In a conventional LC resonance antenna, when a current flows through a booster coil when an information carrier communicates with a reader/writer, a magnetic flux passing through a region surrounded by the booster coil, that is, a non-formation region, is generated.

However, in the conventional LC resonance antenna, since the non-formation region is partially blocked by the capacitor provided in the region, the magnetic flux that attempts to pass through the non-formation region is blocked by the capacitor.

Therefore, in the conventional LC resonance antenna, the magnetic field strength is also attenuated by the amount of the magnetic flux that passes through the region surrounded by the booster coil, and therefore, there is a problem that the communication distance is limited. Further, the problem is not limited to the antenna having the gain coil, and the problem exists in all the LC resonance antennas having the inductor and the capacitor.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2004-287767

Disclosure of Invention

Problems to be solved by the invention

In view of the above circumstances, an object of the present invention is to provide an LC resonance antenna that can extend a communication distance by suppressing a decrease in magnetic flux passing through the inside of an inductor.

Means for solving the problems

The LC resonance antenna of the present invention includes:

an inductor layer provided with a coil-shaped inductor;

a capacitor layer provided with a capacitor and laminated on the inductor layer,

the capacitor has a plurality of electrode plates arranged in a lamination direction of the inductor layer and the capacitor layer with respect to the inductor and extending in a plane direction orthogonal to the lamination direction,

the inductor is formed in such a manner that the axial direction of the coil center coincides or substantially coincides with the stacking direction,

a passage region through which magnetic flux can pass is formed in the plurality of electrode plates, and the passage region corresponds to an inner region surrounded by the inductor in the stacking direction.

In addition, the LC resonance antenna of the present invention may be configured such that,

an expansion region which is continuous with the passage region and through which magnetic flux can pass is formed in the plurality of electrode plates,

the expanded region is formed to extend from the through region to an outer peripheral end of the electrode plate in the face direction.

Drawings

Fig. 1 is a plan view of an LC resonance antenna according to an embodiment of the present invention.

Fig. 2 is a sectional view taken along line II-II of fig. 1.

Fig. 3 is a plan view of the inductor layer of the LC resonance antenna according to this embodiment.

Fig. 4 is a plan view of an inductor of the LC resonance antenna according to this embodiment.

Fig. 5 is a plan view of the capacitor layer of the LC resonance antenna according to this embodiment.

Fig. 6 is a plan view of the electrode plate and the base layer of the LC resonance antenna according to this embodiment.

Fig. 7 is a plan view of the LC resonance antenna of embodiment 1.

Fig. 8 is a plan view of the LC resonance antenna of embodiment 2.

Fig. 9 is a plan view of an LC resonance antenna according to example 3.

Fig. 10 is a plan view of an LC resonance antenna according to example 4.

Fig. 11 is a plan view of an LC resonance antenna according to example 5.

Fig. 12 is a plan view of an LC resonance antenna of a comparative example.

Fig. 13 is a graph showing the results of a communication distance simulation test for the communication distances of examples 1 to 5 and comparative examples.

Fig. 14 is a graph showing the results of a simulation test of the communication distance between the LC resonant antennas of examples 6 and 7 and the LC resonant antenna of comparative example 2.

Detailed Description

Hereinafter, an LC resonance antenna according to an embodiment of the present invention will be described with reference to the drawings. The LC resonance antenna according to the present embodiment is a small-sized antenna incorporated in an article such as an RFID tag or a communication device.

In the present embodiment, the LC resonance antenna is a booster antenna of an on-chip antenna integrally formed on the IC chip itself or a booster antenna of a feeding coil composed of the IC chip and a coil, and the following description is made on the premise that the booster antenna is formed of the on-chip antenna and the feeding coil.

As shown in fig. 1 and 2, the LC resonant antenna includes: a dielectric layer 2 formed by laminating thin sheets, and a resonance circuit (not numbered) provided on the dielectric layer 2.

As shown in fig. 2, the dielectric layer 2 is formed by laminating a first sheet SH1, a second sheet SH2, a third sheet SH3, a fourth sheet SH4 and a fifth sheet SH5, and sintering them by thermocompression bonding, wherein the first sheet SH1 has electrode plates 400 for forming the capacitor 40 formed on one surface and a rectangular metal layer 8 formed on the other surface, the second sheet SH2 has another electrode plate 400 for forming the capacitor 40 formed on one surface, the third sheet SH3 has an inductor 30 formed on one surface, the fourth sheet SH4 covers the inductor 30, and the fifth sheet SH5 has a ring shape (square ring shape in the present embodiment). In the present embodiment, the electrode plate 400 formed on the second sheet SH2 is referred to as a first electrode plate 401, and the electrode plate 400 formed on the first sheet SH1 is referred to as a second electrode plate 402.

In addition, when the thickness direction of the first sheet SH1 is used as a reference, the dielectric layer 2 is formed by laminating a second sheet SH2, a third sheet SH3, a fourth sheet SH4 and a fifth sheet SH5 in this order in the thickness direction on the one surface of the first sheet SH1, laminating the other surface of the second sheet SH2 opposite to the one surface to the second electrode plate 402, and laminating the other surface of the third sheet SH3 opposite to the one surface to the first electrode plate 401 of the second sheet SH 2.

In addition, in the present embodiment, the first sheet SH1 and the metal layer 50 formed on the first sheet SH1 are referred to as a base layer 5; the second electrode plate 402, the second sheet SH2, and the first electrode plate 401 are referred to as a capacitor layer 4; the third sheet SH3 and the inductor 30 are referred to as inductor layer 3; the fourth sheet SH4 is referred to as cover layer 6; the fifth sheet SH5 is referred to as an encapsulating layer 7 and will be described below. In the present embodiment, a direction in which the inductor layer 3 and the capacitor layer 4 overlap each other is referred to as a stacking direction, and a direction orthogonal to the stacking direction is referred to as a plane direction, and the following description will be given.

The first to fifth sheet materials SH1 to SH5 may be formed of individual sheets, or may be formed by stacking a plurality of sheets.

As shown in fig. 3, a coil-shaped (spiral-shaped in the present embodiment) inductor 30 is provided on the inductor layer 3.

The inductor layer 3 of the present embodiment is composed of an inductor 30 and an inductor forming layer 31 for forming the inductor 30. The inductor-forming layer 31 is a third sheet SH 3.

An inductor 30 is formed on a layer surface on the inductor formation layer 31 side in the stacking direction. The other layer surface of the inductor-forming layer 31 in the stacking direction faces the capacitor layer 4. In the present embodiment, as shown in fig. 3, the one-side layer surface of the inductor layer 3 is referred to as an inductor formation surface and denoted by a reference numeral "310", and the other-side layer surface is referred to as an opposite surface, and the following description will be made.

In addition, a pair of via holes (hereinafter, referred to as first via holes) 310a and 310b penetrating in the stacking direction are formed in the inductor forming layer 31.

The pair of first via holes 310a and 310b are different in distance from the respective formation positions to the coil center of the inductor 30 (winding center of the inductor 30). In the present embodiment, the first via hole 310a located farther from the coil center is referred to as an outer peripheral side first via hole 310a, and the first via hole 310b located closer to the coil center is referred to as an inner peripheral side first via hole 310 b.

The inductor 30 is formed of a film-like pattern formed on the inductor-forming surface 310 by using a conductive material (conductive paste in the present embodiment) whose main component is, for example, any of gold, silver, copper, or an alloy thereof. Further, the inductor 30 may be printed on the inductor-forming surface 310 by, for example, screen printing. The pattern may be formed by other printing methods (intaglio, relief, ink jet), or may be formed by any method other than printing, that is, any method capable of obtaining a predetermined pattern shape.

The inductor 30 of the present embodiment is formed of a conductor wire formed in a spiral shape in an annular region along the outer peripheral edge in the installation space of the inductor 30 set in the inductor formation surface 310. Therefore, the central portion side of the installation space (inside of the annular region) is the non-formation region S1 where the inductor 30 (conductor pattern) is not formed. The non-formation region S1 will be described later.

In the present embodiment, one end portion (outer circumferential connecting end portion) 300 on the outer circumferential side of the inductor 30 is formed at a position corresponding to the outer circumferential side first via hole 310a, and one end portion (inner circumferential connecting end portion) 301 on the inner circumferential side of the inductor 30 is formed at a position corresponding to the inner circumferential side first via hole 310 b.

The conductor line includes an outer peripheral line portion 302 extending linearly from a position corresponding to the outer peripheral side first via hole 310a (extending linearly along one side of the outer peripheral end of the inductor formation layer 31 in the present embodiment); a middle line portion 303 extending from the outer peripheral line portion 302 and wound spirally inward; an inner peripheral portion 304 linearly extending from the tip of the middle portion 303 toward the first via hole 310b on the inner peripheral side.

The conductor wire of the present embodiment further includes an inner contact portion 305 formed so as to be continuous with the tip of the inner peripheral portion 304, and the inner contact portion 305 is formed at a position corresponding to the inner peripheral first via hole 310 b. Therefore, in the present embodiment, the outer peripheral connecting end portion 300 is constituted by one end portion in the longitudinal direction of the outer peripheral line portion 302, and the inner peripheral connecting end portion 301 is constituted by the inner contact portion 305.

The non-formation region S1 is explained by referring to a schematic diagram. As shown in fig. 4, the non-formation region S1 is a region divided by a virtual line extending in the same direction as an inner edge (inner edge in the line width direction) of the inner peripheral portion 304 with reference to the edge as a virtual straight line VL, and a point at which the virtual straight line VL first intersects the inner edge of the middle line portion 303 as an intersection point P, in which case the non-formation region S1 is a region divided by the virtual straight line VL and a region from the inner edge of the inner peripheral portion 304, a point from the intersection point of the inner edge of the inner peripheral portion 304 and the inner edge of the middle line portion 303 to the intersection point P. The inner contact portion 305 partially enters the non-formation region S1, and this portion is also referred to as a non-formation region S1.

As shown in fig. 2, the capacitor layer 4 is laminated on the inductor layer 3 in the lamination direction (in other words, the axial direction of the coil center of the inductor 30), and a capacitor 40 is provided.

The capacitor layer 4 of the present embodiment has a pair of electrode plates 400 and an intermediate layer 410 interposed between the pair of electrode plates 400. Therefore, in the present embodiment, the distance between the pair of electrode plates 400 is determined by the thickness of the intermediate layer 410 (the thickness in the stacking direction). Further, the intermediate layer 410 is constituted by the second sheet SH 2.

Of the pair of electrode plates 400, the electrode plate 400 disposed on the inductor layer 3 side (hereinafter referred to as a first electrode plate 401) is formed in a flat sheet shape and is sandwiched between the inductor layer 3 and the intermediate layer 410 in the stacking direction.

As shown in fig. 5, the first electrode plate 401 is provided at a position overlapping with the installation space in a plan view. More specifically, the first electrode plate 401 is provided at a position overlapping a part or the whole of the annular region in a plan view.

The first electrode plate 401 is disposed at a position overlapping the outer peripheral first via hole 310a in a plan view (a position corresponding to the outer peripheral first via hole 310a in the stacking direction), and is electrically connected to the outer peripheral connection end portion 300 via the outer peripheral first via hole 310 a.

As shown in fig. 5, the first electrode plate 401 of the present embodiment includes: an inner region (first inner region) S2a formed inside the outer peripheral edge portion; adjacent regions (first adjacent regions) S2b that are continuous (adjacent) in the plane direction with respect to the first inner region S2 a.

The first inner region S2a is a region formed so as to be open in the stacking direction. In addition, the first inner region S2a is a rectangular region in plan view, and is formed at a position accommodated in the non-formation region S1. Therefore, the inner peripheral end (hereinafter referred to as a first inner peripheral end) 401a of the first electrode plate 401 is also formed at a position housed in the non-formation region S1 in a plan view.

The first adjacent region S2b is formed to extend from the first inner region S2a toward the outside in the face direction, and in addition, the first adjacent region S2b is formed to be open toward the face direction at the outer peripheral end of the first electrode plate 401.

In the first electrode plate 401 of the present embodiment, a portion of the outer peripheral edge portion is cut out in a discontinuous manner, thereby forming the first adjacent region S2 b. Meanwhile, a pair of opposite ends (hereinafter, referred to as first opposite ends) 401b are formed at the outer peripheral edge portion of the first electrode plate 401 to face each other with a space therebetween.

The electrode plate (hereinafter, referred to as a second electrode plate) 402 arranged so as to be aligned in the stacking direction with the first electrode plate 401 via the intermediate layer 410 (arranged so as to overlap in a plan view) is formed in a flat sheet shape. As shown in fig. 2, the second electrode plate 402 is sandwiched between a base layer, which will be described later, and a layer surface of the intermediate layer 410 on the other side in the stacking direction.

The second electrode plate 402 is disposed at a position overlapping the inner peripheral side first via hole 310b (a position corresponding to the inner peripheral side first via hole 310b in the stacking direction) in plan view, and is electrically connected to the inner peripheral connection end portion 301 via the inner peripheral side first via hole 310 b.

Further, the second electrode plate 402 of the present embodiment has formed therein: an inner region (second inner region) S3a formed inside the outer peripheral edge portion, and an adjacent region (second adjacent region) S3b which is continuous (adjacent) with respect to the second inner region S3a in the plane direction.

The second inner region S3a is a region formed so as to be open in the stacking direction. The second inner region S3a is a rectangular region in plan view and is formed at a position accommodated in the first inner region S2 a. Therefore, the second inner region S3a is also formed at a position housed in the non-formation region S1 in a plan view. Meanwhile, in the present embodiment, the inner peripheral end (hereinafter, referred to as a second inner peripheral end) 402a of the second electrode plate 402 is also formed at a position housed in the first inner region S2a and the non-formation region S1.

In this way, the second inner region S3a is formed at a position overlapping the first inner region S2a in plan view (a position housed in the first inner region S2 a), and a passage region through which the magnetic flux generated from the inductor 30 can pass is configured by a region overlapping the first inner region S2a and the second inner region S3a in plan view. The first inner region S2a and the second inner region S3a may be regions through which magnetic flux can pass, and may be made of a material through which magnetic flux can pass.

The second adjacent region S3b is formed to extend outward in the surface direction from the second inner region S3a, and the second adjacent region S3b is formed to be open in the surface direction at the outer peripheral end of the second electrode plate 402.

In the second electrode plate 402 of the present embodiment, a part of the outer peripheral edge portion is cut out in a discontinuous manner, thereby forming the second adjacent region S3 b. Meanwhile, a pair of opposite ends (hereinafter, referred to as second opposite ends) 402b are formed at the outer peripheral edge portion of the second electrode plate 402 to face each other with a space therebetween.

The second adjacent region S3b is formed at a position overlapping the first inner region S2a and the first adjacent region S2b in a plan view (a position accommodated in the first adjacent region S2 b). Therefore, the first inner region S2a and the first adjacent region S2b overlap with the second adjacent region S3b in plan view to form an expanded region that extends from the passing region in the plane direction (outward in the plane direction) and through which magnetic flux can pass. In the present embodiment, although there is a region where the second adjacent region S3b overlaps the first adjacent region S2b in a plan view, the second adjacent region S3b does not necessarily overlap the first adjacent region S2 b. In the present embodiment, the first adjacent region S2b is formed to include the second adjacent region S3b in a plan view, but the second adjacent region S3b may be formed to include the first adjacent region S2b, for example. The first adjacent region S2b and the second adjacent region S3b may be regions through which magnetic flux can pass, and for example, a material through which magnetic flux can pass may be present inside.

In the LC resonance antenna 1, the magnetic flux generated from the inductor 30 flows unimpeded in the region where the passing region and the expanded region overlap with the non-formation region S1 in a plan view. Therefore, in the present embodiment, the regions located within the non-formation region S1 in a plan view, out of the passage region and the extension region, are collectively referred to as the passage-allowing regions.

In the intermediate layer 410, a via hole (hereinafter referred to as a second via hole) 410a is formed at a position corresponding to the inner peripheral side first via hole 310b and the second electrode plate 402 in the stacking direction. Therefore, in the present embodiment, the inner peripheral connecting end portion 301 of the inductor 30 and the second electrode plate 402 are electrically connected to each other through the inner peripheral first via hole 310b and the second via hole 410 a.

As described above, in LC resonant antenna 1 of the present embodiment, outer circumferential connecting end 300 is electrically connected to first electrode plate 401, and inner circumferential connecting end 301 is electrically connected to second electrode plate 402, thereby configuring a resonant circuit that electrically connects inductor 30 and capacitor 40.

The dielectric layer 2 of the present embodiment includes, in addition to the inductor layer 3 and the capacitor layer 4, a base layer 5 laminated on the other side of the intermediate layer 410 of the capacitor layer 4 (the side of the intermediate layer 410 opposite to the inductor layer 3 side); a cover layer 6 laminated on the inductor layer 3; and an encapsulation layer 7 laminated on the cover layer 6.

In the base layer 5, the layer surface on one side in the stacking direction is opposed to the layer surface on the other side of the intermediate layer 410. Further, a metal layer 50 having a rectangular shape in a bottom view is provided on the other layer surface of the base layer 5 in the stacking direction.

The cover layer 6 includes a cover surface that is a surface facing the inductor-forming surface 310 and a reference surface 60 that is a surface opposite to the cover surface in the stacking direction, and a part of the outer surface of the dielectric layer 2 is constituted by the reference surface 60. The reference surface 60 is a plane located closest to the inductor 30 in the stacking direction, out of planes located on the opposite side of the stacking direction of the capacitor layer 4 with respect to the inductor layer 3, and in the present embodiment, is a plane surrounded by a peripheral wall layer 70 described later, out of the outer surface (upper surface) of the cover layer 6.

The sealing layer 7 includes an annular peripheral wall layer 70 laminated on the reference surface 60 of the cover layer 6.

In the present embodiment, one installation recess 701 is formed by the inner peripheral surface 700 of the peripheral wall layer 70 and the region corresponding to the opening of the peripheral wall layer 70 in the reference surface 60 of the cover layer 6.

Further, the reference surface 60 may be laminated with a peripheral wall layer 70, or may be laminated with two or more peripheral wall layers 70.

The installation recess 701 is a space for installing the IC chip C, and for example, the IC chip C can be integrated with the LC resonance antenna 1 by placing the IC chip C on the reference surface 60 and then filling the installation recess 701 with resin. The IC chip C may be a power supply coil formed of an IC chip and a coil.

The LC resonance antenna 1 of the present embodiment has the above-described structure. Next, a method of manufacturing the LC resonance antenna 1 of the present embodiment will be described.

The sheet material constituting the dielectric layer 2 is prepared by applying a slurry to a tape (tape) and drying the tape. The slurry is prepared by stirring ceramic powder, glass powder (low-melting glass frit), organic binder, and organic solvent.

Since the sheet material is manufactured so that the entire thickness thereof is constant, each sheet material is manufactured to have the thickness of each layer constituting the dielectric layer 2.

After the sheet material is dried, the tape is peeled off and removed, and then a sheet having a predetermined size is cut out from the sheet material. In this embodiment, a sheet cut from a sheet material is referred to as a printed circuit board.

Next, through holes are formed as the outer peripheral side first via hole 310a and the inner peripheral side first via hole 310b on the printed circuit board for the inductor layer 3 by punching or laser. Then, a through hole as the second via hole 410a is formed in the printed circuit board as the intermediate layer 410 by punching or laser.

Then, a pattern suitable for the shape of the inductor 30 is formed on the printed circuit board for the inductor layer 3 by screen printing using a conductive paste. At this time, the outer circumference side first via hole 310a and the inner circumference side first via hole 310b are filled with the conductive paste. Then, the conductive paste patterned and the conductive paste filled in the outer peripheral side first via hole 310a and the inner peripheral side first via hole 310b are dried.

The first electrode plate 401 is printed on the printed circuit substrate for the intermediate layer 410 through a conductive paste, and the second via hole 410a is filled with the conductive paste. Then, the conductive paste constituting the first electrode plate 401 and the conductive paste filled in the second via hole 410a are dried.

The second electrode plate 402 is printed on one side face of the printed circuit substrate for the base layer 5 by a conductive paste, and the metal layer 50 is printed on the other side face.

Further, on the printed circuit board for the inductor layer 3, a plurality of inductor 30 patterns for the LC resonance antenna 1, an outer periphery side first via hole 310a, and an inner periphery side first via hole 310b are formed.

Further, a plurality of first electrode plates 401 for the LC resonance antenna 1 and second via holes 410a are formed on the printed circuit board for the intermediate layer 410. Similarly, the second electrode plate 402 for the LC resonance antenna 1 and the metal layer 50 are printed on the printed circuit board for the base layer 5.

After the respective sheets constituting the dielectric layer 2 are produced, the sheets are laminated in a predetermined order, and in this state, the sheets are thermocompression bonded to produce a laminate, and then the laminate is sintered to produce a sintered body.

The firing step is carried out by removing organic substances contained in the laminate at a temperature not higher than the softening point of the glass component, for example, about 500 ℃, and then firing at a temperature determined by the melting point of the glass component or the conductive material used for the wiring portion, for example, 800 to 1050 ℃.

The conductive portion (the metal layer 50 in the present embodiment) peeled off from the surface of the sintered body is subjected to electroless plating with Ni (nickel), and then electroless plating with Au (gold).

Then, the plurality of LC resonance antennas 1 formed on one sintered body are cut out one by a dicer. Thus, the LC resonance antenna 1 is manufactured.

In addition, when the thickness of the sheet is changed in manufacturing the LC resonance antenna 1, the distance between the first electrode plate 401 and the second electrode plate 402 (distance between the electrode plates), the distance between the inductor 30 and the capacitor 40 (specifically, the first electrode plate 401 of the capacitor 40) in the stacking direction, and the distance between the inductor 30 and the reference plane 60, which are intended to suppress variations, are also changed, and therefore, it is important to control the thickness of the sheet after each manufacturing process to a desired thickness.

For example, in the step of thermocompression bonding the sheets to each other (thermocompression bonding step) or the step of sintering the sheets (sintering step), the thickness of the sheets changes due to the influence of shrinkage or the like, and in the step of printing the inductor 30, the first electrode plate 401, the second electrode plate 402, and the metal layer 50 (printing step), the thickness of the sheets changes due to the influence of the shape and size of the conductor pattern, the position of the via hole, or the like.

Therefore, in the present embodiment, in the step of manufacturing the sheet material, that is, in the step of applying the slurry to the tape (the applying step), the thickness of each sheet of the manufactured LC resonance antenna 1 can be made to a desired size by adjusting the thickness of the slurry applied to the tape in consideration of the thickness variation of the sheet in the thermocompression bonding step, the sintering step, and the printing step. More specifically, the thickness of the sheet can be adjusted by applying the slurry to the belt by the doctor blade method and adjusting the height of the blade edge of the doctor blade at that time.

In the subsequent steps, it is also preferable to control the manufacturing conditions in the subsequent steps so that the thickness change is stable and always changes at the same value.

As described above, with the LC resonance antenna 1 of the present embodiment, the magnetic flux generated from the inductor 30 flows so as to pass through the inner region surrounded by the inductor 30.

In the LC resonance antenna 1, the inductor 30 and the capacitor 40 (electrode plate 400) are arranged in the stacking direction, but since the electrode plate 400 has a passage region through which magnetic flux can pass, the passage region corresponding to an inner region surrounded by the inductor 30 in the stacking direction, the flow of magnetic flux that attempts to pass through the inner region surrounded by the inductor 30 can be prevented from being blocked by the electrode plate 400.

Therefore, the LC resonance antenna 1 of the present embodiment can exhibit the following excellent effects: the reduction of the magnetic flux passing through the inside of the inductor 30 is suppressed, and the communication distance can be extended.

In addition, since the electrode plate 400 is formed with the expanded region extending from the passing region to the outer circumferential end in the plane direction, the portion around the passing region of the electrode plate 400 is discontinuous in the circumferential direction.

Therefore, in the LC resonance antenna 1, the magnetic flux generated from the inductor 30 does not generate an eddy current around the passing region of the electrode plate 400 when passing through the passing region.

Therefore, the LC resonance antenna 1 does not generate an eddy current that weakens the magnetic flux passing through the passage area, and thus can suppress the weakening of the magnetic flux passing through the inside of the inductor.

The LC resonance antenna according to the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

In the above-described embodiment, the LC resonance antenna 1 has been described on the premise of a booster antenna which is an on-chip antenna or a booster antenna which is a feeding coil composed of an IC chip and a coil, but the LC resonance antenna 1 is not limited to this, and may be, for example, a main antenna of an IC chip in which an antenna is not integrally formed.

In the above embodiment, the inductor 30 is formed in a spiral shape, but is not limited to this structure. For example, inductor 30 may also be helical. In the case of forming the spiral inductor 30, for example, a plurality of patterns formed on the layer surface of each layer may be connected to each other by a conductive material.

In the above embodiment, although not particularly mentioned, the dimensions of the inductor 30 and the first electrode plate 401 and the second electrode plate 402 of the capacitor 40 in the plane direction can be changed as appropriate.

In the above embodiment, the encapsulating layer 7 is laminated on the cover layer 6, but the encapsulating layer 7 may not be laminated on the cover layer 6. Further, the case where the package layer 7 is laminated on the cover layer 6 enables the IC chip C and the LC resonance antenna 1 to be easily formed integrally.

In the above embodiment, the metal layer 50 is laminated on the dielectric layer 2 (base layer 5), but the metal layer 50 may not be laminated on the base layer 5. In addition, when the LC resonance antenna 1 is configured to include the metal layer 50, the resonance circuit can be designed in advance in consideration of the influence of the metal on the resonance frequency, and therefore, the resonance frequency can be prevented from changing even when the LC resonance antenna 1 is mounted on a metal structure or the like.

Example 1

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

(example 1)

As shown in fig. 7, an LC resonance antenna 1 having the same configuration as that of the above embodiment was prepared as example 1. In example 1, the area of the non-formation region S1 is H _ac Setting the area of the allowed passing region as H _ai In the case of (3), the opening ratio a obtained by the following formula 1 was 66.83%.

[ number 1]

(example 2)

As shown in fig. 8, an LC resonance antenna 1 was prepared as example 2, and this LC resonance antenna 1 had the same configuration as the above-described embodiment, and was configured such that the aperture ratio a determined from equation 1 was 93.35%.

(example 3)

As shown in fig. 9, an LC resonance antenna 1 was prepared as example 3, and this LC resonance antenna 1 had the same configuration as the above-described embodiment and was configured such that the aperture ratio a determined from equation 1 was 40.31%.

(example 4)

As shown in fig. 10, an LC resonance antenna 1 was prepared as example 4, and this LC resonance antenna 1 had the same configuration as the above-described embodiment and was configured such that the aperture ratio a determined from equation 1 was 14.51%.

(example 5)

As shown in fig. 11, an LC resonance antenna 1 was prepared as example 5, and this LC resonance antenna 1 had the same configuration as the above-described embodiment and was configured such that the aperture ratio a determined from equation 1 was 2.74%.

Comparative example

As shown in fig. 12, an LC resonance antenna 1 was prepared as a comparative example, and this LC resonance antenna 1 had the same layer structure as the above-described embodiment and was configured such that the aperture ratio a determined from equation 1 was 0%. In the LC resonance antenna of the comparative example, the capacitor 40 is configured by the electrode plate 400, the electrode plate 400 is configured by the first electrode plate 401 and the second electrode plate 402 shown in fig. 12, the first inner region S2a and the first adjacent region S2b described in the above embodiment are not provided in the first electrode plate 401, the second inner region S3a and the second adjacent region S3b described in the above embodiment are not provided in the second electrode 402, and the electrode plate 400 is not formed with the passing region and the expanded region.

(simulation test of communication distance)

The communication distances of the LC resonant antennas 1 of examples 1 to 5 and comparative example were calculated by simulation. In the simulation calculation, the communication distance was calculated for the LC resonance antennas 1 of examples 1 to 5 and comparative example at the same magnetic field strength. The magnetic field strength is set to 0.0200A/m, which is a minimum level considered necessary for communication. The reference of the communication distance is the surface of the LC resonance antenna 1.

(evaluation of simulation test of communication distance)

The results of the simulation test of the communication distance are shown in fig. 13. In fig. 13, the results (communication distances) of the tests of the LC resonant antennas 1 of examples 1 to 5 are denoted by "P1 to P5", and the results (communication distances) of the tests of the LC resonant antenna 1 of the comparative example are denoted by "P6".

As shown in fig. 13, comparing the communication distance P6 of the LC resonance antenna 1 of the comparative example with the communication distances P1 to 5 of the LC resonance antennas 1 of examples 1 to 5, it is clear that the communication distance is longer when the passage region and the extension region are formed in the electrode plate 400 constituting the capacitor 40.

As is clear from comparison of the communication distances P1 to P5 of the LC resonance antennas 1 of examples 1 to 5, the communication distance increases as the aperture ratio a increases, but the communication distance does not change between the LC resonance antenna 1 configured such that the aperture ratio a becomes 66.83% and the LC resonance antenna 1 configured such that the aperture ratio a becomes larger than 66.83%. As is clear from the results of the simulation test of the communication distance shown in fig. 13, the aperture ratio is preferably 2% or more, more preferably 30% or more, and most preferably 60% or more.

(simulation test for improving communication distance by providing an opening in an electrode plate of a capacitor)

Next, a simulation test for improving the communication distance will be described.

In this test, in each of examples 2 and 3 and the comparative example, the communication distance was obtained by performing a simulation calculation on the electromagnetic field while changing the distance (interval) between the inductor 30 and the capacitor 40 (specifically, the first electrode plate 401 of the capacitor 40) in the stacking direction. In examples 2 and 3 and comparative examples, the distance between the inductor 30 and the capacitor 40 when the communication distance is obtained is shown in table 1 below.

[ TABLE 1]

(evaluation of simulation test for improving communication distance by providing an opening in an electrode plate of a capacitor)

As shown in fig. 14, in the LC resonance antenna of the comparative example, if the distance between the inductor 30 and the capacitor 40 having no opening is narrow, the communication distance is reduced, and it is understood from this that, if the distance between the inductor 30 and the capacitor 40 is narrow, the magnetic flux generated from the inductor 30 is blocked by the capacitor 40. In addition, a horizontal axis D1 in fig. 14 represents a distance between the inductor 30 and the first electrode plate 401 of the capacitor.

Further, as the distance between the inductor 30 and the capacitor 40 becomes narrower, the communication distance of the LC resonance antenna of the comparative example is significantly reduced from the communication distance of the LC resonance antennas of examples 2 and 3, and therefore, it is understood that when the capacitor 40 is located within the range through which the magnetic flux generated from the inductor 30 passes, the flow of the magnetic flux can be improved by forming the opening in the capacitor 40, and that the narrower the distance between the inductor 30 and the capacitor 40, the better the effect of improving the flow of the magnetic flux by forming the opening.

Further, if the distance between the inductor 30 and the capacitor 40 is narrow, the communication distance of the LC resonance antenna of example 3 is reduced compared to the communication distance of the LC resonance antenna of example 2, and thus it is understood that the improvement effect of the flow of the magnetic flux can be improved by increasing the aperture ratio a.

Description of reference numerals

1 … resonant antenna, 2 … dielectric layer, 3 … inductor layer, 4 … capacitor layer, 5 … base layer, 6 … cover layer, 7 … encapsulation layer, 30 … inductor, 31 … inductor forming layer, 40 … capacitor, 50 … metal layer, 60 … reference plane, 70 … surrounding wall layer, 300 … outer peripheral connection end portion, 301 … inner peripheral connection end portion, 302 … outer peripheral line portion, 303 … middle line portion, 304 … inner peripheral line portion, 305 … inner contact portion, 310 … inductor forming plane, 310a … first via (outer peripheral side first via), 310b … first via (inner peripheral side first via), 400 … electrode plate, 401 … first electrode plate, 402 … second electrode plate, 410 … middle layer, 410a … second via, 700 …, inner peripheral surface 701 … setting recess, a … aperture ratio, C … chip, P … intersection point, S … non-forming region, S … inner region, the S2b … first adjacent region, the S3a … second inner region, the S3b … second adjacent region, VL … imaginary straight line.

Claims (5)

1. An LC resonant antenna, having:

an inductor layer provided with a coil-shaped inductor;

a capacitor layer provided with a capacitor and laminated on the inductor layer,

the capacitor has a plurality of electrode plates arranged in a lamination direction of the inductor layer and the capacitor layer with respect to the inductor and extending in a plane direction orthogonal to the lamination direction,

the inductor is formed in such a manner that the axial direction of the coil center coincides or substantially coincides with the stacking direction,

a passage region through which magnetic flux can pass is formed in the plurality of electrode plates, and the passage region penetrates in the stacking direction at a position corresponding to an inner region surrounded by the inductor in the stacking direction.

2. The LC resonance antenna according to claim 1,

the plurality of electrode plates includes electrode plates larger than an inner region surrounded by the inductor.

3. The LC resonance antenna according to claim 1,

one of the capacitors is disposed in the capacitor layer,

the plurality of electrode plates is a pair of electrode plates.

4. The LC resonant antenna of claim 2,

one of the capacitors is disposed in the capacitor layer,

the plurality of electrode plates is a pair of electrode plates.

5. The LC resonance antenna according to any one of claims 1 to 3,

an expansion region which is continuous with the passage region and through which magnetic flux can pass is formed in the plurality of electrode plates,

the expanded region is formed to extend from the passing region to an outer peripheral end of the electrode plate in the face direction.