JPWO2019150936A1 - Ni-Zn-Cu-based ferrite powder, electronic components, antennas and RF tags - Google Patents

Abstract

An object of the present invention is to obtain a Ni—Zn—Cu based ferrite powder having desired magnetic characteristics even in a frequency band such as 60 MHz. The Ni-Zn-Cu-based ferrite powder of the present invention contains Fe2O3, NiO, ZnO, CuO and CoO in a predetermined composition ratio, and the molar ratio (Ni / Zn) of Ni to Zn contained is 3. It is a Ni—Zn—Cu based ferrite powder of 8 to 5.8, and the constituent phases of the ferrite powder are spinel type ferrite and NiO, and the μQ product at 60 MHz is 3500 or more.

Description

The present invention relates to a Ni—Zn—Cu based ferrite material, and more specifically, provides a Ni—Zn—Cu based ferrite material having excellent characteristics even in a higher frequency band.

In recent years, the miniaturization and weight reduction of electronic devices for home and industrial use have progressed, and along with this, the needs for miniaturization, high efficiency, and high frequency of electronic components used in the above-mentioned various electronic devices have increased. There is.

For example, it is assumed that the power inductor operates in a high frequency band, and the ferrite material used for the power inductor is also required to be able to maintain desired characteristics even in a high frequency band such as 60 MHz.

Conventionally, it has been described that ferrite having a specific composition is used in an inductance component having a structure wound around a core having a high magnetic permeability (Patent Document 1).

Japanese Unexamined Patent Publication No. 9-63826

However, in the technique described in Patent Document 1, ferrite having a low μ "of 120 MHz is described in the examples for the purpose of obtaining an inductance component used at a relatively low frequency of several to several tens of MHz, but 60 MHz. Sufficient characteristics could not be obtained in the frequency band of.

Therefore, an object of the present invention is to obtain a Ni—Zn—Cu based ferrite powder having desired magnetic characteristics even in a frequency band such as 60 MHz.

The technical subject can be achieved by the present invention as follows.

That is, in the present invention, Fe ₂ O ₃ is 46 to 50 mol%, NiO is 30 to 40 mol%, ZnO is 1.0 to 10 mol%, CuO is 9.0 to 11 mol%, and CoO is 0.01 to 1. It is a Ni—Zn—Cu based ferrite powder containing 0 mol% and having a molar ratio (Ni / Zn) of Ni to Zn contained in the amount of 3.8 to 5.8 (the present invention 1).

Further, the present invention is the Ni—Zn—Cu based ferrite powder according to the present invention 1, wherein the constituent phases are spinel type ferrite and NiO (the present invention 2).

Further, the present invention is the Ni—Zn—Cu based ferrite powder according to the present invention 2 in which the crystallite size of the spinel type ferrite is 240 nm or more (the present invention 3).

Further, the present invention is the Ni—Zn—Cu based ferrite powder according to any one of the present inventions 1 to 3 having a μQ product at 60 MHz of 3500 or more (the present invention 4).

Further, the present invention is a green sheet formed into a sheet by using the Ni—Zn—Cu-based ferrite powder according to the present invention 1 or 2 and a bonding material (the present invention 5).

Further, in the present invention, Fe ₂ O ₃ is 46 to 50 mol%, NiO is 30 to 40 mol%, ZnO is 1.0 to 10 mol%, CuO is 9.0 to 11 mol%, and CoO is 0.01 to 1. It is a Ni-Zn-Cu based ferrite sintered body containing 0 mol% and having a molar ratio (Ni / Zn) of Ni to Zn contained in the mixture of 3.8 to 5.8 (the present invention 6).

Further, the present invention is an electronic component composed of a ferrite core and a coil, and the ferrite core is an electronic component which is the sintered body according to the sixth aspect of the present invention (7).

Further, the present invention is an antenna composed of the electronic components described in the present invention 7 (invention 8).

The Ni—Zn—Cu-based ferrite powder according to the present invention exhibits excellent characteristics in a high frequency region such as 60 MHz, and is therefore suitable as a ferrite powder for a power inductor.
Further, the electronic component using the Ni—Zn—Cu-based ferrite powder according to the present invention has a large μQ product and exhibits excellent characteristics in a high frequency region, and is therefore suitable as various electronic components.

It is a block diagram of the coil part of the electronic component which concerns on this invention. It is a conceptual diagram which shows the laminated structure of the electronic component which concerns on this invention. It is a conceptual diagram which shows another aspect of the laminated structure of the electronic component which concerns on this invention.

The Ni—Zn—Cu based ferrite powder according to the present invention will be described. The Ni—Zn—Cu based ferrite powder of the present invention described below defines the entire powder, and does not necessarily define only the ferrite itself constituting the powder. The Ni-Zn-Cu-based ferrite powder contains Ni-Zn-Cu-based ferrite as a main component, and is a mixture of Ni-Zn-Cu-based ferrite and other components as described below. You may.

The Ni—Zn—Cu-based ferrite powder according to the present invention contains Fe, Ni, Zn, Cu and Co as constituent metal elements. Each constituent metal _{elements, Fe 2 O 3, NiO,} ZnO, when converted to CuO and _{CoO, Fe 2 O 3, NiO,} ZnO, the total of CuO and CoO (100%) based, _Fe 2 _{O 3} 46 to 50 mol%, NiO 30 to 40 mol%, ZnO 1.0 to 10 mol%, CuO 9.0 to 11 mol%, and CoO 0.01 to 1.0 mol%.

The Fe content of the Ni—Zn—Cu based ferrite powder according to the present invention is 46 to 50 mol% in terms of _{Fe 2} O _3. If the Fe content is less than 46 mol%, μ'will be small, and if the Fe content is more than 50 mol%, sintering will not be possible. The Fe content is preferably 46.5 to 49.5 mol%, more preferably 47.0 to 49.0 mol%.

The Ni content of the Ni—Zn—Cu-based ferrite powder according to the present invention is 30 to 40 mol% in terms of NiO. If the Ni content is less than 30 mol%, μ ”is high in a high frequency region such as 60 MHz and the μQ product is lowered, which is not preferable. If the Ni content is more than 40 mol%, μ'is lowered, which is not preferable. The Ni content is preferably 30.5 to 39.5 mol%, more preferably 31 to 39 mol%.

The Zn content of the Ni—Zn—Cu-based ferrite powder according to the present invention is 1.0 to 10 mol% in terms of ZnO. If the Zn content is less than 1.0 mol%, μ'will decrease, which is not preferable. When the Zn content exceeds 10 mol%, μ "becomes large. The Zn content is preferably 1.5 to 9.5 mol%, more preferably 2 to 9 mol%.

The Cu content of the Ni—Zn—Cu-based ferrite powder according to the present invention is 9.0 to 11 mol% in terms of CuO. When the Cu content is less than 9.0 mol%, the sinterability is lowered, and it becomes difficult to produce a sintered body at a low temperature. If the Cu content exceeds 11 mol%, μ'decreases, which is not preferable. The Cu content is preferably 9.1 to 10.9 mol%, more preferably 9.2 to 10.8 mol%.

The Co content of the Ni-Zn-Cu-based ferrite powder according to the present invention is 0.01 to 1.0 mol% in terms of CoO. In the present invention, since the limit line of the snake shifts to the high frequency side due to the inclusion of Co in the ferrite, the real part μ'with respect to the imaginary part μ "of the complex magnetic permeability in the high frequency region (for example, 13.56 MHz)". The Q (μ'/ μ ") of the ferrite core, which is the ratio of, can be improved. However, when the Co content exceeds 1.0 mol% in terms of CoO, the magnetic permeability tends to decrease, and the Q of the ferrite core also tends to decrease. The Co content is preferably 0.05 to 0.95 mol%, more preferably 0.10 to 0.90 mol%.

The Ni-Zn-Cu based ferrite powder according to the present invention has a molar ratio (Ni / Zn) of Ni to Zn contained in the Ni-Zn-Cu based ferrite powder of 3.8 to 5.8. By adjusting the molar ratio of Ni to Zn within this range, a high μQ product can be obtained in a high frequency region such as 60 MHz. The molar ratio of Zn to Ni is preferably 3.75 to 5.75, more preferably 3.73 to 5.73, and even more preferably 3.70 to 5.70.

The Ni-Zn-Cu-based ferrite powder according to the present invention preferably contains a molar ratio (Ni / Cu) of Ni to Cu of 3.0 to 3.4. By adjusting the molar ratio of Ni and Cu within this range, a high μQ product can be obtained in a high frequency region such as 60 MHz. More preferably, the molar ratio of Ni to Cu is 3.05 to 3.35, and even more preferably 3.1 to 3.30.

The Ni-Zn-Cu-based ferrite powder according to the present invention preferably contains a molar ratio of Cu to Zn (Cu / Zn) of 1.0 to 1.5. By adjusting the molar ratio of Cu and Zn within this range, a high μQ product can be obtained in a high frequency region such as 60 MHz. More preferably, the molar ratio of Cu to Zn is 1.05 to 1.45, and even more preferably 1.1 to 1.40.

The Ni-Zn-Cu-based ferrite powder according to the present invention may contain various elements at the impurity level in addition to the above elements as long as the characteristics are not affected. Generally, it is known that the addition of Bi has the effect of lowering the sintering temperature of ferrite. However, since the temperature reduction and the control of the crystal structure in the present invention are adjusted by the molar ratio of Zn and Ni (Zn / Ni) and the content of Cu, the effect of further lowering the sintering temperature is expected by the addition. However, the refinement of the crystal structure is further promoted, and there is a high possibility that μ'decrease or μQ product decrease occurs, and aggressive Bi addition is not preferable, and 0 ppm is preferable.

The Ni-Zn-Cu-based ferrite powder according to the present invention may contain Si as an unavoidable impurity up to 300 ppm in terms of _{SiO 2.} It is preferable that Sn and the like are not contained (0 ppm).

The Ni—Zn—Cu based ferrite powder according to the present invention preferably has substantially only spinel-type ferrite and NiO as its constituent phases. That is, it is preferable that the mixture is a spinel-type ferrite formed by forming each of Fe, Ni, Zn, Cu and Co into one body, and NiO existing in addition to the spinel-type ferrite formed by forming one body. In the composition of the present invention, it is not preferable to obtain only a spinel-type ferrite as a constituent phase because μ ”is high in a high frequency region such as 60 MHz and the μQ product is lowered. Further, a phase other than spinel-type ferrite and NiO is not preferable. For example, when hematite (Fe ₂ O ₃ ) is present, it is not preferable because the μQ product decreases in a high frequency region such as 60 MHz (that is, _{it is preferable that hematite (Fe 2} O ₃ ) is not present).

Of the spinel-type ferrite and NiO constituting the Ni-Zn-Cu-based ferrite powder according to the present invention, 90 wt% or more of the spinel-type ferrite may be contained (NiO is contained in an amount of 10 wt% or less and more than 0 wt%). preferable. If the content of spinel-type ferrite is less than 90 wt%, it becomes difficult to obtain a desired magnetic permeability. The identification of the constituent phases and the confirmation of the content ratio were calculated by the method described later based on X-ray diffraction.

The Ni-Zn-Cu-based ferrite powder according to the present invention preferably has a crystallite size of 240 nm or more measured for spinel-type ferrite among its constituent phases. By controlling the crystallite size of the Ni—Zn—Cu-based ferrite powder according to the present invention within the above range, μ ′ can be increased. The crystallite size is more preferably 242 to 300 nm.

The Ni-Zn-Cu-based ferrite powder according to the present invention preferably has a lattice constant of 8.365 Å or more for spinel-type ferrite among its constituent phases. By controlling the lattice constant of the Ni—Zn—Cu-based ferrite powder according to the present invention within the above range, μ ′ can be increased. The lattice constant is more preferably 8.366 Å or more.

The Ni-Zn-Cu-based ferrite powder according to the present invention preferably has a strain of 0.325 to 0.400 for spinel-type ferrite among its constituent phases. By controlling the strain of the Ni-Zn-Cu-based ferrite powder according to the present invention within the above range, μ'can be increased. The strain is more preferably 0.326 to 0.390.

In the Ni-Zn-Cu-based ferrite powder according to the present invention, μ'at 13.56 MHz is preferably 20 to 50, μ'is preferably 0.1 to 0.5, and the Q value is preferably 100 to 300. The μQ product is preferably 4500 to 10000.
The μ'at 60 MHz is preferably 20 to 60, the μ'is preferably 0.1 to 0.5, the Q value is preferably 40 to 200, and the μQ product is 3500 or more, more preferably 3800 to 10000. Is preferable.

The Ni-Zn-Cu-based ferrite powder according to the present invention is prepared by mixing raw materials such as oxides, carbonates, hydroxides, and oxalates of each element constituting ferrite in a predetermined composition ratio by a conventional method. Obtained by precipitating the obtained raw material mixture or co-precipitate obtained by precipitating each element in an aqueous solution in the air in a temperature range of 650 to 950 ° C. for 1 to 20 hours and then pulverizing. be able to.

Next, the green sheet according to the present invention will be described.

The green sheet is made into a paint by mixing the Ni-Zn-Cu-based ferrite powder with a bonding material, a plasticizer, a solvent, etc., and the paint is made into a thickness of several μm to several hundred μm with a doctor blade type coater or the like. A sheet that is dried after being formed into a film. After stacking these sheets, pressurization is performed to form a laminate, and the laminate is sintered at a predetermined temperature to obtain an inductance element.

The green sheet according to the present invention contains 2 to 20 parts by weight of a bonding material and 0.5 to 15 parts by weight of a plasticizer with respect to 100 parts by weight of the Ni—Zn—Cu based ferrite powder according to the present invention. Preferably, it contains 4 to 15 parts by weight of the binding material and 1 to 10 parts by weight of the plasticizer. Further, the solvent may remain due to insufficient drying after the film formation. Further, if necessary, a known additive such as a viscosity modifier may be added.

The types of binding materials are polyvinyl butyral, polyacrylic acid ester, polymethylmethacrylate, vinyl chloride, polymethacrylic acid ester, ethylene cellulose, abietic acid resin and the like. A preferred binding material is polyvinyl butyral.

If the bonding material is less than 2 parts by weight, the green sheet becomes brittle, and the content of more than 20 parts by weight is not necessary to have strength.

The types of plasticizers are benzyl-n-butyl phthalate, butyl butylphthalyl glycolate, dibutyl phthalate, dimethyl phthalate, polyethylene glycol, phthalate ester, butyl stearate, methyl agitate and the like.

If the amount of the plasticizer is less than 0.5 parts by weight, the green sheet becomes hard and cracks are likely to occur. If the plasticizer exceeds 15 parts by weight, the green sheet becomes soft and difficult to handle.

In the production of the green sheet according to the present invention, 15 to 150 parts by weight of a solvent is used with respect to 100 parts by weight of the Ni—Zn—Cu based ferrite powder. If the solvent is out of the above range, a uniform green sheet cannot be obtained, so that the inductance element obtained by sintering the solvent tends to have variations in characteristics.

The type of solvent is acetone, benzene, butanol, ethanol, methyl ethyl ketone, toluene, propyl alcohol, isopropyl alcohol, n-butyl acetate, 3methyl-3methoxy-1butanol and the like.

The stacking pressure is preferably ^{0.2 × 10 4 to} 0.6 × 10 ⁴ t / m ^2.

Next, the Ni—Zn—Cu based ferrite sintered body according to the present invention will be described.

The Ni-Zn-Cu-based ferrite sintered body according to the present invention uses a mold to prepare the Ni-Zn-Cu-based ferrite powder according to the present invention at 0.3 to 3.0 × 10 ⁴ t / m ² . Obtained by the so-called green sheet method, in which a molded product obtained by a so-called powder pressure molding method, which is pressurized by pressure, or a green sheet containing a Ni-Zn-Cu-based ferrite powder according to the present invention is laminated. The laminate can be obtained by sintering the laminate at 850 to 150 ° C. for 1 to 20 hours, preferably 1 to 10 hours. As a molding method, a known method can be used, but the powder pressure molding method and the green sheet method are preferable.

If the sintering temperature is less than 850 ° C., the sintering density is lowered, so that the mechanical strength of the sintered body is lowered. If the sintering temperature exceeds 1050 ° C., the sintered body is likely to be deformed, and it becomes difficult to obtain a sintered body having a desired shape. A more preferable sintering temperature is 880 to 1020 ° C.

The Ni-Zn-Cu-based ferrite sintered body according to the present invention can be used as a magnetic material for an inductance element by forming it into a predetermined shape.

The Ni-Zn-Cu-based ferrite sintered body according to the present invention can be used in the form of a plate.

The thickness of the ferrite sintered plate in the present invention is preferably 0.01 to 1 mm. It is more preferably 0.02 to 1 mm, and even more preferably 0.03 to 0.5 mm.

An adhesive layer can be provided on at least one surface of the ferrite sintered plate in the present invention. The thickness of the adhesive layer is preferably 0.001 to 0.1 mm.

A protective layer can be provided on at least one surface of the ferrite sintered plate in the present invention. The thickness of the protective layer is preferably 0.001 to 0.1 mm.

The μ'of the ferrite sintered sheet in the present invention is preferably 80 to 300. It is even more preferably 90 to 290, and even more preferably 110 to 280.

The μ "of the ferrite sintered sheet in the present invention is preferably 0.05 to 15, more preferably 0.06 to 10, and even more preferably 0.07 to 5.0.

Examples of the adhesive layer in the present invention include double-sided adhesive tape. The double-sided adhesive tape is not particularly limited, and a known double-sided adhesive tape can be used. Further, as the adhesive layer, an adhesive layer, a flexible and stretchable film or sheet, an adhesive layer and a release sheet may be sequentially laminated on one side of a ferrite sintered plate.

By providing the protective layer in the present invention, it is possible to improve the reliability and durability against powder dropping when the ferrite sintered plate is divided. The protective layer is not particularly limited as long as it is a resin that stretches without breaking when the ferrite sintered sheet is bent, and a PET film or the like is exemplified.

The ferrite sintered sheet in the present invention has at least one groove provided in advance on at least one surface of the ferrite sintered plate in order to attach it in close contact with the bent portion and to prevent it from cracking during use. The ferrite sintered plate may be configured to be divisible as a starting point. The groove may be continuous or intermittently formed, and can be used as a substitute for the groove by forming a large number of minute recesses. The groove is preferably U-shaped or V-shaped in cross section.

In the ferrite sintered sheet of the present invention, it is preferable to divide the ferrite sintered plate into small pieces in advance in order to attach the ferrite sintered sheet in close contact with the bent portion and to prevent cracking during use. For example, the ferrite sintered plate may be divided in advance starting from at least one groove provided on at least one surface of the ferrite sintered plate, or the ferrite sintered plate may be divided into small pieces without forming a groove. Any method may be used.

Ferrite sintered plates are divided into triangles, quadrilaterals, polygons, or combinations thereof of arbitrary sizes by grooves. For example, the length of one side of a triangle, quadrilateral, or polygon is usually 1 to 12 mm, and when the adhesive surface of the adherend is a curved surface, it is preferably 1 mm or more and 1/3 or less of the radius of curvature. More preferably, it is 1 mm or more and 1/4 or less. When the groove is formed, it can be adhered or substantially adhered to not only a flat surface but also a columnar side curved surface and a surface having some unevenness without being irregularly cracked at a place other than the groove.

The width of the groove opening formed in the ferrite sintered plate is usually preferably 250 μm or less, and more preferably 1 to 150 μm. If the width of the opening exceeds 250 μm, the magnetic permeability of the ferrite sintered plate is significantly reduced, which is not preferable. The groove depth is usually 1/20 to 3/5 of the thickness of the ferrite sintered plate. In the case of a thin sintered ferrite plate having a thickness of 0.1 mm to 0.2 mm, the groove depth is preferably 1/20 to 1/4, more preferably 1/4 of the thickness of the sintered ferrite plate. It is 20 to 1/6.

The Ni-Zn-Cu-based ferrite sintered body according to the present invention can be used as a magnetic material for an antenna by forming it into a predetermined shape.

The antenna according to the present invention is used, for example, for RFID tags, and the real part μ'of the complex magnetic permeability of the ferrite core at 13.56 MHz is preferably 80 or more. If it is less than 80, the desired Q and μQ products cannot be obtained, and excellent communication characteristics cannot be obtained in the antenna. It is more preferably 100 or more, and even more preferably 110 or more.

Further, in the antenna according to the present invention, it is desirable that the imaginary part μ "of the complex magnetic permeability of the ferrite core at 13.56 MHz is 2 or less. If it exceeds 2, μ" suddenly increases due to a slight frequency shift. As a result, Q decreases, and excellent communication characteristics cannot be obtained in the antenna. It is more preferably 1.5 or less, and even more preferably 1.0 or less.

In the antenna according to the present invention, the Q (μ'/ μ ") of the ferrite core, which is the ratio of the real part μ'to the imaginary part μ" of the complex magnetic permeability at 13.56 MHz of the ferrite core, is 50 to 170. preferable. When the Q (μ'/ μ ") of the ferrite core is less than 50, the communication distance of the antenna becomes short and it becomes unsuitable for the antenna. The Q (μ' / μ") of the ferrite core at 13.56 MHz is more preferable. It is 70 to 165, and even more preferably 80 to 160.

In the antenna according to the present invention, the μQ product, which is the product of the real part μ'of the complex magnetic permeability of the ferrite core at 13.56 MHz and the Q of the ferrite core, is preferably 9000 or more. If it is less than 9000, excellent communication characteristics cannot be obtained. The μQ product is more preferably 10,000 or more, and even more preferably 12,000 or more.

The electronic component according to the present invention includes a coil made of a conductor around which the ferrite core is wound, on the outside of the ferrite core. In the coil, the ferrite base material to be the ferrite core and the conductive material to be the coil are integrally fired in order to suppress variations in electrical characteristics such as inductance, or from the viewpoint of productivity, and the conductor is in close contact with the outside of the ferrite core. It is preferable to have. That is, the electronic component in the present invention is preferably made of a sintered body having a ferrite core and a coil.

As the conductor constituting the coil, a metal such as Ag or Ag-based alloy, copper or copper-based alloy can be used, and Ag or Ag-based alloy is preferable.

The electronic component according to the present invention preferably has a coil made of a conductor on the outside of the ferrite core, and preferably has an insulating layer on one or both outer surfaces. By providing the insulating layer, the coil is protected and a homogeneous electronic component of a quality that operates stably can be obtained.

The electronic component according to the present invention has an appropriate amount of non-magnetic ferrite such as Zn-based ferrite, borosilicate glass, glass-based ceramic such as zinc-based glass or lead-based glass, or non-magnetic ferrite and glass-based ceramic as an insulating layer. Can be used.

Ferrite used as a non-magnetic ferrite in the insulating layer has a volume specific resistance of 10 in the sintered body.⁸It is preferable to select a Zn-based ferrite composition having a concentration of Ω cm or more. For example, Fe₂O ₃The composition is preferably 45.0 to 49.5 mol%, ZnO is 17.0 to 45.0 mol%, and CuO is 4.5 to 15.0 mol%.

When the insulating layer is a glass-based ceramic, the glass-based ceramic to be used may have a composition in which the coefficient of linear expansion does not significantly differ from the coefficient of linear expansion of the magnetic material used. Specifically, the composition is such that the difference from the coefficient of linear expansion of magnetic ferrite used as a magnetic material is within ± 5 ppm / ° C.

The electronic component according to the present invention may include a conductive layer on the outside of the coil on the ferrite core via an insulating layer. By providing the conductive layer, even if a metal object approaches the antenna, the change in the resonance frequency of the antenna becomes small, and a homogeneous antenna of a quality that operates stably can be obtained.

The electronic component according to the present invention may be provided with a metal layer as a conductive layer, and is preferably a thin layer of metal made of Ag or an Ag-based alloy having low resistance.

The electronic component according to the present invention is preferably a sintered body in which the insulating layer and the conductive layer are integrally fired together with a ferrite base material to be a ferrite core and a conductive material to be a conductor and adhere to the ferrite core.

A small and highly sensitive antenna as obtained by the present invention is desired to be applied to a wearable device, and in that case, the size of the antenna is preferably 1 cm square or less and 1 cm or less in height.

The RF tag in the present invention has an IC chip connected to the antenna. As the RF tag in the present invention, the antenna and the connected IC chip are protected without impairing the characteristics even if the RF tag is coated with a resin, and a quality RF tag that operates stably can be obtained.

A method for manufacturing an electronic component according to the present invention will be described.

The electronic component according to the present invention can be manufactured by various methods in which a coil can be provided so as to wind a ferrite core. Here, a method for manufacturing an antenna by the LTCC (Low Temperature Co-fired Ceramics) technology, in which a sheet-shaped ferrite base material and a conductive material are laminated so as to have a desired configuration and then integrally fired. Will be described.

A laminated configuration of antennas as shown in FIGS. 1 and 2 will be described as an example.

First, a ferrite base material is formed by forming a sheet of a mixture of a magnetic powder and a binder.

The magnetic powder contains Fe, Ni, Zn, Cu and Co as constituent metal elements, and when each of the constituent metal elements _{is converted into Fe 2} O ₃ , NiO, ZnO, CuO and CoO, Fe ₂ O ₃ , NiO, ZnO, based on the total of CuO and CoO, _Fe 2 _{O 3} the 46~50mol%, 20~27mol% of NiO, 15~22mol% of ZnO, 9~11mol% of CuO, and CoO 0. Ferrite calcined powder containing 01 to 1.0 mol% can be used.

Next, the magnetic layer (5) made of a ferrite base material is laminated so that the total thickness becomes a desired thickness. As shown in FIG. 1, a desired number of through holes (1) are formed in the laminated body of the magnetic layer (5). A conductive material is poured into each of the through holes (1). Further, electrode layers (2) are formed on both sides of the laminated body of the magnetic layer (5) at right angles to the through holes (1) so as to be connected to the through holes (1) to form a coil (winding). To do. The coil (4) is formed by the conductive material and the electrode layer (2) poured into the through hole (1) so that the laminated body of the magnetic layer (5) becomes the core of a rectangular parallelepiped. At this time, both ends of the magnetic layer forming the coil (4) are open on the magnetic circuit.

As the conductive material that is poured into the through hole (1) or forms the electrode layer (2), a metal-based conductive paste can be used, and an Ag paste or an Ag-based alloy paste is suitable.

The obtained sheet-like laminate is cut at the surface including the through hole (1) and the coil open end surface (4-2) and integrally fired so as to have a desired shape, or after the integral firing, the through hole (through hole (1)) The antenna of the present invention made of a sintered body having a ferrite core (3) and a coil (4) can be manufactured by cutting with a surface including 1) and an open end surface (4-2) of the coil.

The firing temperature of the laminate is 800 ° C. to 1000 ° C., preferably 850 ° C. to 920 ° C. If the temperature is lower than the above range, it becomes difficult to obtain desirable characteristics in μ'and Q, and if the temperature is high, it becomes difficult to perform integral firing.

Further, in the present invention, the insulating layer (6) can be formed on the upper and lower surfaces of the magnetic layer (5) on which the electrode layer (2) is formed. A schematic view of the antenna on which the insulating layer (6) is formed is shown in FIG.

Further, in the antenna of the present invention, an IC may be mounted by forming a coil lead terminal and an IC chip connection terminal on the surface of the insulating layer (6) with a conductive material.

In the antenna in which the IC chip connection terminal is formed, a through hole is provided in an insulating layer (6) formed on at least one surface of the magnetic layer (5) in which the electrode layer (2) is formed, and a conductive material is provided in the through hole. Is poured, connected to both ends of the coil (4), formed on the surface of the insulating layer (6) with a conductive material so that the coil lead terminal and the IC chip connection terminal can be connected in parallel or in series, and integrally fired. Can be done.

Further, the antenna according to the present invention may be provided with a conductive layer (7) outside the insulating layer (6) as shown in FIG. By providing the magnetic layer (5) on which the antenna forms the coil (4) with the conductive layer (7) via the insulating layer (6), the change in resonance frequency is small even when the antenna is attached to a metal surface, and the coil is directly connected. By not touching the metal surface, a uniform antenna of stable operation quality can be obtained.

Further, the antenna according to the present invention may be further provided with an insulating layer (6) on the outer surface of the conductive layer (7) as shown in FIG. Further, a magnetic layer (5) or a magnetic layer (5) and an insulating layer (6) may be provided on the outer surface of the insulating layer (6). As a result, even if a metal object approaches the antenna, the change in the characteristics of the antenna becomes smaller, and the change in the resonance frequency can be made smaller.

The conductive layer (7) may be formed by any means, but it is preferable to form the conductive layer (7) on the insulating layer (6) by a usual method such as printing or brushing with a paste-like conductive material. Alternatively, a metal plate can be attached to the outside of the insulating layer (6) to give the same effect.

As the paste-like conductive material forming the conductive layer (7), a metal-based conductive paste can be used, and Ag paste and Ag-based alloy paste are suitable.

When the conductive layer (7) is formed on the outside of the insulating layer, the film thickness of the conductive layer (7) is preferably 0.001 to 0.1 mm after firing.

Further, in the antenna of the present invention, the capacitor electrodes may be arranged on the outer surfaces of one or both of the insulating layers (6) sandwiching the upper and lower surfaces of the coil (4).

The antenna may be a capacitor formed by printing a parallel electrode or a comb-shaped electrode on the capacitor formed on the upper surface of the insulating layer (6), and further, the capacitor and the coil lead terminal may be connected in parallel or in series. May be good.

Further, in the antenna according to the present invention, a terminal provided with a variable capacitor may be formed on the upper surface of the insulating layer (6), and the coil lead terminal and the coil lead terminal may be connected in parallel or in series.

Further, an insulating layer (6) is further provided on the outer surface on which the capacitor electrode is arranged on the upper surface of the insulating layer (6), and an electrode layer also serving as an IC chip connection terminal is formed on the outer surface of the insulating layer (6) to insulate the insulating layer (6). A capacitor may be formed so as to sandwich the layer (6), and may be connected in parallel or in series with the IC chip connection terminal.

In the antenna according to the present invention, a through hole (1) is provided in the insulating layer (6) on the lower surface of the coil (4), a conductive material is poured into the through hole, and the antenna is connected to both ends of the coil (4), and the lower surface thereof. A substrate connection terminal may be formed of a conductive material and integrally fired. In that case, it can be easily bonded to a substrate such as ceramic or resin.

The IC chip may be connected by forming an IC chip connection terminal on the insulating layer, or by forming wiring in the board so as to connect to the board connection terminal on the lower surface of the antenna, via the wiring in the board. You may connect. By connecting an IC chip, the antenna in the present invention can be used as an RF tag.

Further, the RF tag in the present invention is made of a resin such as polystyrene, acrylonitrile styrene, acrylonitrile butagen styrene, acrylic, polyethylene, polypropylene, polyamide, polyacetal, polycarbonate, vinyl chloride, modified polyphenylene ether, polybutylene terephthalate, and polyphenylene sulfide. It may be covered.

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In the antenna according to the present invention, when the ferrite core _{converts Fe, Ni, Zn, Cu and Co into Fe 2} O ₃ , NiO, ZnO, CuO and CoO _{, respectively, Fe 2} O ₃ , NiO, ZnO, Based on the total of CuO and CoO, Fe ₂ O ₃ is 46 to 50 mol%, NiO is 30 to 40 mol%, ZnO is 1.0 to 10 mol%, CuO is 9.0 to 11 mol%, and CoO is 0.01. A magnetic material containing ~ 1.0 mol%, which has a high Q and μQ product at 13.56 MHz and 60 MHz.

In the antenna manufactured by using the ferrite powder according to the present invention, since the ferrite powder has the above characteristics, the communication sensitivity of the antenna can be improved.

Hereinafter, the present invention will be specifically described with reference to examples of the present invention.

[Measurement of ferrite composition]
The composition of the above-mentioned ferrite calcined powder for the ferrite core was measured using a multi-element simultaneous fluorescent X-ray analyzer Simultix 14 (Rigaku Co., Ltd.).

[Identification and quantification of crystal phase]
The crystal phase constituting ferrite was evaluated using D8 ADVANCE.

[Crystal size, lattice constant]
The crystallite size and lattice constant of ferrite were determined by using D8 ADVANCE in the same manner as in the X-ray diffraction, and the TOPAS software Ver. It was evaluated in 4.

[Measurement of magnetic properties of ferrite core]
A powder obtained by mixing 15 g of the above-mentioned ferrite calcined powder for a ferrite core and 1.5 mL of a 6.5% diluted PVA aqueous solution was put into a mold having an outer diameter of 20 mmφ and an inner diameter of 10 mmφ, and was charged at 1 ton / cm with a press machine. A ferrite ring core for measuring the initial magnetic permeability, Q, and μQ product was obtained by compressing with ^{2 and firing at 900 ° C. for 2 hours under the same conditions as when manufacturing an antenna.}

The magnetic permeability, Q, and μQ products of the ring core were measured at a frequency of 13.56 MHz using an impedance / material analyzer E4991A (manufactured by Agilent Technologies, Inc.).

Example 1:
Each oxide raw material was weighed so that the composition of Ni-Zn-Cu-Co ferrite had a predetermined composition, wet mixing was performed, and then the mixed slurry was filtered off and dried to obtain a raw material mixed powder. The calcined product obtained by calcining the raw material mixed powder at 830 ° C. for 2 hours was pulverized with a vibration mill to obtain a Ni-Zn-Cu-Co ferrite powder according to the present invention.

After adding and mixing 10 parts by weight of PVA (polyvinyl alcohol) with 100 parts by weight of the obtained Ni-Zn-Cu-Co ferrite powder, 3.5 g of the powder is weighed and the outer diameter is 20 mm using a mold. Pressurized molding to an inner diameter of 12 mm and a height of 5 mm (press pressure 1.0 x 10)⁴t / m ²)did. Table 1 shows the magnetic properties of the ferrite sintered body obtained by sintering this molded body at a sintering temperature of 900 ° C. for 2 hours.

In the evaluation of the obtained Ni-Zn-Cu-Co ferrite by XRD, the presence of NiO could be confirmed with spinel ferrite as the main phase. The ratio was 96.04% for spinel ferrite and 3.96% for NiO. The crystallite size for spinel ferrite was 243 nm and the lattice constant was 8.36910 Å.

Examples 2-4, Comparative Examples 1-6
A Ni-Zn-Cu-Co ferrite powder was obtained in the same manner as in Example 1 except that the composition range was variously changed. Tables 1 and 2 show various characteristics of the obtained Ni-Zn-Cu-Co ferrite powder.

[Example 5 Manufacture of antenna]
A slurry was produced by mixing 100 parts by weight of Ni-Zn-Cu ferrite calcined powder of Example 3, 8 parts by weight of butyral resin, 5 parts by weight of a plasticizer, and 80 parts by weight of a solvent with a ball mill. The resulting slurry was molded on a PET film with a doctor blade at a size of 150 mm square so that the thickness at the time of sintering was 0.1 mm to obtain a green sheet for the magnetic layer (5). Table 1 shows the magnetic properties of the ferrite core obtained by sintering this green sheet at a firing temperature of 900 ° C.

Also, Zn-Cu ferrite calcined powder _{(Fe 2 O 3 46.5mol%,} ZnO 42.0mol%, CuO 11.5mol%) 100 parts by weight, 8 parts by weight of a butyral resin, 5 parts by weight of a plasticizer, a solvent 80 weight The parts were mixed with a ball mill to produce a slurry. The resulting slurry was molded on a PET film with a doctor blade in the same size and thickness as the green sheet for the magnetic layer (5) to obtain a green sheet for the insulating layer (6).

Next, a through hole (1) is opened at a predetermined position on 10 green sheets for the magnetic layer (5), and Ag paste is filled therein, and an electrode is used on the surface to be provided with the electrode layer (2). Pattern was printed. These 10 green sheets were laminated to form a coil-shaped laminate on the outside of the green sheet on which the conductive material was laminated. The green sheet for the insulating layer (6) was laminated on the surface on which the conductive material to be the electrode layer of the laminated body was printed.

The laminated green sheets are pressure-bonded together, cut at the surface that divides the through hole (1) and the open end surface of the coil (4-2), and integrally fired at 900 ° C. for 2 hours, 10 mm wide x 3 mm long. An antenna made of a sintered body having a ferrite core and a coil having a coil winding number of 23 turns of the same size was created (in FIG. 2, the coil winding number is shown in 7 turns for simplification of the figure). , The number of laminated magnetic layers (5) is represented by three layers for the sake of simplification of the figure. The same applies to the other figures below.)

[Measurement of communication distance]
An RF tag IC is connected to both ends of the coil of the antenna, and a condenser is connected in parallel with the IC to adjust the resonance frequency so that the communication distance is maximized to manufacture an RF tag, and a reader / with an output of 100 mW. The antenna of the writer (manufactured by Takaya Co., Ltd., product name TR3-A201 / TR3-D002A) is fixed horizontally, and the central axis of the coil of the RF tag antenna is positioned so that it faces vertically on the center of the reader / writer antenna. The maximum communication distance was defined as the distance between the reader / writer antenna and the RF tag when communication was at the highest possible position.

Based on the longest communication distance of the antenna manufactured in Comparative Example 2, the relative value of the longest communication distance of the antennas of the other examples was calculated as a percentage.

The antenna using Ni-Zn-Cu-Co ferrite powder of Example 1 was 103%, Example 2 was 104%, Example 3 was 109%, and Example 4 was 113%.

As a result of various changes in the composition of the ferrite core of the antenna having the same size and structure in the examples and comparative examples of the present invention, improvement in communication sensitivity was observed at the composition specified in the present invention.

It was confirmed that the antenna in the present invention has a high Q (μ'/ μ ") of the ferrite core used for the ferrite core, and is an antenna that achieves both miniaturization and improvement of communication sensitivity.

1 Through hole 2 Electrode layer (coil electrode)
3 cores (magnetic material)
4 Coil 5 Magnetic layer 6 Insulation layer 7 Conductive layer

Claims (8)

Fe ₂ O ₃ is 46 to 50 mol%, NiO is 30 to 40 mol%, ZnO is 1.0 to 10 mol%, CuO is 9.0 to 11 mol%, and CoO is 0.01 to 1.0 mol%. A Ni-Zn-Cu based ferrite powder characterized in that the molar ratio (Ni / Zn) of Ni to Zn is 3.8 to 5.8. The Ni-Zn-Cu based ferrite powder according to claim 1, wherein the constituent phases are spinel-type ferrite and NiO. The Ni-Zn-Cu based ferrite powder according to claim 2, wherein the crystallite size of the spinel-type ferrite is 240 nm or more. The Ni—Zn—Cu based ferrite powder according to any one of claims 1 to 3, wherein the μQ product at 60 MHz is 3500 or more. A green sheet formed into a sheet using the Ni—Zn—Cu-based ferrite powder according to claim 1 or 2 and a bonding material. Fe ₂ O ₃ is 46 to 50 mol%, NiO is 30 to 40 mol%, ZnO is 1.0 to 10 mol%, CuO is 9.0 to 11 mol%, and CoO is 0.01 to 1.0 mol%. A Ni-Zn-Cu based ferrite sintered body having a molar ratio (Ni / Zn) of Ni to Zn of 3.8 to 5.8. An electronic component composed of a ferrite core and a coil, wherein the ferrite core is the sintered body according to claim 6. An antenna made of the electronic component according to claim 7.

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