JP2013133263A - Ferrite magnetic material and production method thereof, ferrite fired body using the same and antenna module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ferrite magnetic material which has proper and stable commuication performance in the RFID system and the NFC system for mobile terminals inserted with the ferrite fired body in between the reader/writer communication spiral antenna and the metal surface of the mobile terminal housing cell, to provide a production method thereof, and to provide a ferrite fired body using the same and an antenna module.SOLUTION: The ferrite magnetic material includes 100 pts.wt. of a major component comprising 46.7-48.7 mol% of FeO, 19.3-21.3 mol% of NiO, 10.05-12.05 mol% of CuO and 19.95-21.95 mol% of ZnO; and at least 0.2-1.2 pt.wt. of the compound: (1-X)CoO-XFeO(provided that X: 0.48-0.54 mol) and 0.5-1.5 pt.wt. of CuO as minor components, wherein at least one of the major component and the minor components is a solid solution having a spinel type crystalline structure.

Description

  The present invention is an RFID system or NFC system for a portable terminal comprising a reader / writer exchange spiral antenna, and even if there is a metal or electric field substance that affects a magnetic field on the back surface of the RFID antenna or NFC antenna, low loss ( A magnetic material that improves the communication function by using a magnetic material having a high Q value), a ferrite magnetic material for shielding the influence of an object affected by a magnetic field on the back surface (generation of eddy current), and a method for manufacturing the same The present invention relates to a sintered ferrite body and an antenna module using the same.

  That is, in the RFID system and the NFC system, a thin plate-like ferrite fired body is inserted between the RFID antenna or the NFC antenna and the metal surface of the mobile terminal housing cell in order to ensure good communication performance. The present invention relates to a ferrite magnetic material necessary for obtaining good and stable communication performance in a portable terminal RFID system and an NFC system, a manufacturing method thereof, a ferrite sintered body using the ferrite magnetic material, and an antenna module. .

  RFID that supports the ubiquitous society has been put into practical use in various fields, and one example is the mounting of a contactless IC card function on a mobile phone. The non-contact IC card function mounted on the mobile phone performs communication using electromagnetic induction at 13.56 MHz, and a magnetic substance is provided between the coiled antenna provided inside and other metal parts. In order to achieve the desired communication performance by suppressing adverse effects such as eddy current loss, further improvement in communication performance and reduction in size and thickness are desired.

  For example, a 13.56 MHz band RFID system (IC tag, wireless communication using an IC card) comprising a reader / writer spiral antenna is used as a structure in which an IC tag is incorporated into a thin resin card, as a convenience store specification electronic money card or mobile phone. Applied to the terminal. And as a next development, efforts to install in 13.56 MHz band NFC system have been in full swing.

  The 13.56 MHz band RFID system and the NFC system perform power supply and communication by electromagnetic induction generated between spiral antennas provided in both the reader / writer and the wireless tag.

  However, various studies have been made to mount the 13.56 MHz band RFID system on a mobile terminal, but unlike a case where it is incorporated into a thin resin card, a housing located near the communication spiral antenna of the mobile terminal. The communication performance was significantly impaired by the metal surface of the body cell. That is, when the magnetic flux generated in the spiral antenna penetrates the metal surface, eddy current centering on the magnetic flux flows through the metal surface according to Faraday's law, but the direction of rotation flows in the direction opposite to the direction of the current flowing through the spiral antenna. . That is, since the magnetic flux generated in the spiral antenna is canceled by the magnetic flux in the opposite direction due to the eddy current generated on the metal surface, the communication performance of the RFID system is greatly attenuated.

  Therefore, in order to prevent such a situation, a magnetic material having permeability such as ferrite is applied. That is, by inserting a magnetic material having a magnetic permeability between the spiral antenna and the metal surface of the housing cell, the magnetic material focuses the magnetic flux before the magnetic flux generated in the spiral antenna penetrates the metal surface. This suppresses the generation of eddy currents on the metal surface.

For example, (Patent Document 1) discloses a non-contact type IC card reader / writer in which a flexible magnetic material is disposed between a reader / writer and a metal surface. According to this, in order to suppress the above problems caused by the metal surface, a flexible magnetic material is applied to ensure stable reading and writing of the IC card reader / writer. On the other hand, (Patent Document 2) discloses a ferrite powder containing SiO ₂ in a Ni—Zn-based ferrite powder composed of Fe ₂ O ₃ , NiO, and ZnO as a ferrite material. An example in which a sintered ferrite body fired at 1300 ° C. is applied to an inductance element is described.

  In order to improve the communication performance of the RFID antenna and the NFC antenna, it is necessary to insert a magnetic material having a high magnetic permeability and a high Q value between the spiral antenna and the metal surface of the casing cell as described above. There is. As a method for improving the Q value of a magnetic material (Patent Document 3), a magnetic ferrite material mainly composed of iron oxide, zinc oxide, nickel oxide and copper oxide is added with bismuth oxide and cobalt oxide. An example in which the Q value is improved and applied to an inductance element is disclosed.

Furthermore, (Patent Document 4) contains CoO in Fe ₂ O ₃ , NiO, ZnO, and CuO as an element that reduces eddy current loss while increasing the permeability in order to improve the communication performance of the antenna module. There is disclosed a ferrite material and an antenna module magnetic core member having a product of permeability and Q value of 300 or more using the ferrite material.

JP 2002-298095 A JP 2007-145703 A JP 2001-348226 A JP 2005-340759 A

  However, the above-mentioned conventional flexible magnetic body, ferrite magnetic material, and sintered ferrite body and member produced thereby are intended to improve the magnetic permeability and Q value. It was hard to say that it was designed in consideration of the relationship between uniform dispersibility, selective reactivity and communication performance. That is, the fine structure of the fired body, the magnetic permeability, and the Q value fluctuate due to factors that cannot be controlled in the process, such as inevitably error factors in manufacturing, and as a result, communication performance and other performances may be degraded. there were. The communication performance may vary depending on the composition and manufacturing conditions of the ferrite magnetic material, the manufacturing method, the structure and the microstructure of the sintered ferrite body.

  Further, in order to cope with higher performance and higher functionality of NFC and RFID, it is necessary to acquire a high level of communication performance, and it is necessary to further improve the conventional level of magnetic permeability and Q value.

  For example, a flexible sheet-like magnetic body disclosed in (Patent Document 1) is a ferrite composite in which a soft magnetic powder is kneaded with an organic binder to form a sheet. A high magnetic permeability cannot be obtained due to the fine structure in which soft magnetic powder is dispersed in the matrix. Therefore, when the flexible sheet-like magnetic material is applied to an RFID system for mobile terminals or an NFC system, the effect of converging the magnetic flux generated in the spiral antenna is not sufficient, the eddy current loss due to the metal casing is large, and good communication There was concern that performance could not be acquired.

After the ferrite sintered body disclosed in (Patent Document 2) is formed into a green sheet by forming a Ni-Zn ferrite powder composed of Fe ₂ O ₃ , NiO, and ZnO and containing SiO ₂ into a green sheet, The sintered body is fired at 1100 to 1300 ° C., and becomes a high permeability fired body having a dense microstructure in which the crystal grains are greatly grown by the progress of sintering due to the addition of SiO ₂ and a high firing temperature. Therefore, when the fired body is applied to an RFID system for portable terminals or an NFC system, a high magnetic permeability is obtained due to a dense fine structure composed of excessively grown crystal particles, but in a high frequency band of 13.56 MHz. At the same time as the conductivity increases, the eddy current loss of the fired body itself increases, the Q value decreases, the effect of converging the magnetic flux generated in the spiral antenna is not exhibited, the power loss becomes significant, and sufficient communication performance as described above is achieved. There was a fear that it could not be acquired.

The magnetic ferrite material disclosed in (Patent Document _3), Fe ₂ O 3, ZnO, NiO, and with respect to the main component consisting of CuO, less than the _Bi 2 _{O 3} as an auxiliary component 2 wt%, Co ₃ O ₄ is added less than 0.1 wt%. However, in the manufacturing method, the selective calcining method of the mixture of the main component and the subcomponent described above is used, and the selective reactivity of the subcomponent having the effect of improving the Q value and the firing temperature is greatly impaired. It was difficult to improve the Q value while maintaining the above.

Furthermore, the ferrite material disclosed in (Patent Document 4) includes 47.0 to 49.8 mol% of Fe ₂ O ₃ , 16.0 to 33.0 mol% of NiO, and 11.0 to 25 of ZnO. This is a bulk ferrite containing 0.0 mol% and 7.0 to 12.0 mol% of CuO, and 0.1 to 1.0 wt% of CoO is appropriately contained therein.

  The point for achieving a sufficient Q value improvement while maintaining high magnetic permeability is the addition of CoO. However, as described above, the relationship between the selective reactivity of CoO and the communication performance is not fully considered, and the material process There was room for improvement.

  As described above, the conventional technique is intended to improve the permeability and Q value in the high frequency band, but considers the uniform dispersibility, selective reactivity, and the like of the additive, which are essential components for improving the communication performance. It was not a material design. At the same time, in order to cope with high performance and high performance of NFC and RFID, there is sufficient room for improvement in the material composition system composed of main components and subcomponents.

  In addition, when applying the sintered ferrite body in the prior art to RFID systems for mobile terminals and NFC systems, the relationship between the fine structure of the sintered body composed of a predetermined ferrite material composition and communication performance has been grasped in detail. There wasn't. In other words, in the RFID system and NFC system configured by inserting a ferrite fired body between the spiral antenna and the metal surface of the mobile terminal housing cell, the microstructure of the ferrite fired body that achieves the maximum communication performance is established. Was not.

  Therefore, the present invention solves the above-described problems. An RFID system or NFC for portable terminals in which a sintered ferrite body is inserted between a reader / writer exchange spiral antenna and a metal surface of a portable terminal housing cell. It is an object of the present invention to provide a ferrite magnetic material that exhibits good and stable communication performance in a system, a method for producing the same, a fired ferrite body using the ferrite magnetic material, and an antenna module.

To this end, the ferrite magnetic material of the present invention, from 46.7 to 48.7 mol% of _Fe 2 _O 3, _19.3~21.3 mol% of NiO, 10.05 to 12.05 The compound (1-X) Co ₂ O ₃ .XFe ₂ O ₃ (provided X: at least as an accessory component) with respect to 100 parts by weight of the main component consisting of mol% CuO and 19.95 to 21.95 mol% ZnO 0.48 to 0.54 mol) is contained in an amount of 0.2 to 1.2 parts by weight, and CuO is contained in an amount of 0.5 to 1.5 parts by weight, and at least one of the main component and the subcomponents. One or more is a solid solution having a spinel crystal structure. A method of manufacturing a ferrite magnetic material of the present invention, from 46.7 to 48.7 mol% of _Fe 2 _O 3, _19.3~21.3 mol% of NiO, of 10.05 to 12.05 mol% A step of preparing a main component powder by calcining a mixture of CuO and 19.95 to 21.95 mol% of ZnO at a predetermined temperature, XFe ₂ O ₃ and (1-X) Co ₂ O ₃ ( Wherein X: 0.48 to 0.54 mol) is calcined at a predetermined temperature to produce a subcomponent powder, and the subcomponent powder is added in an amount of 0.1% to 100 parts by weight of the main component powder. 2 to 1.2 parts by weight, CuO 0.5 to 1.5 parts by weight, each of which is mixed and then sequentially mixed, and at least one of the main component powder and the subcomponent powder Is a solid solution with a spinel crystal structure It is intended to. Thereby, selective reactivity of CoO which is an essential component for improving the Q value while maintaining high magnetic permeability is achieved.

That is, a general soft ferrite material has a spinel crystal structure represented by the general formula MO · Fe ₂ O ₃ (where Fe ₂ O ₃ is 50 mol% or less and M is a divalent metal). doing. In the trivalent Fe ³⁺ located at the center of the regular octahedral structure, the balanced equation Fe ³⁺ + e−⇔ · Fe ²⁺ causes the electrons to move easily, which may lead to a decrease in the Q value that affects the communication performance. is there. Therefore, by Fe ³⁺ and ionic radius to solid solution close Co ^2+, enter Co ²⁺ is substituted with Fe ³⁺ in the center position of the octahedral structure, an improvement in Q value by suppressing the electron exchange reaction of the above It is intended. In particular, the present invention relates to a compound (1-X) Co ₂ O ₃ .XFe ₂ O ₃ (where X is 0.48 to 0.8.0) which is a subcomponent obtained by selectively reacting CoO and Fe ₂ O ₃ in advance. 54 mol), the substitution of Fe ^{3+ with} Co ²⁺ is surely generated at the center position of the regular octahedral structure to improve the performance of the ferrite magnetic material.

On the other hand, when a main component mixture and subcomponents without calcining are applied, it is difficult to form a solid solution having a uniform spinel crystal structure, and it is difficult to achieve selective reactivity of CoO. Therefore, since the ferrite sintered body having a small permeability and a low Q value and a hematite phase that is a single phase of Fe ₂ O ₃ is generated, good communication performance cannot be obtained.

  Further, the ferrite sintered body manufactured from the above ferrite magnetic material is characterized in that the microstructure is composed of crystal grains in the process of grain growth and pores of several μm or less, and thus, sintered ferrite. A ferrite fired body having a high Q value and a small temperature change rate of the magnetic permeability is obtained while maintaining a high magnetic permeability at a communication frequency of 13.56 MHz of the antenna module including the body, and the product of the magnetic permeability and the Q value is 10,000. That's it. And the antenna module which has the favorable and stable communication performance in which the communication distance in 13.56 MHz exceeds 110 mm by applying the said ferrite sintered compact to RFID system or NFC system.

  As described above, according to the present invention, a ferrite magnetic material having a high magnetic permeability and a good Q value and a method for producing the same are provided. Good communication by applying the ferrite sintered body manufactured from the ferrite magnetic material to the RFID system or NFC system for portable terminals inserted between the reader / writer exchange spiral antenna and the metal surface of the portable terminal housing cell An antenna module having performance can be realized.

Diagram showing the manufacturing method of ferrite magnetic material Powder X-ray diffraction pattern of Fe ₂ O ₃ —Co ₂ O ₃ -based auxiliary component calcined product Powder X-ray diffraction pattern of ferrite magnetic material The figure which shows the fine structure with respect to the firing temperature of the ferrite sintered body Schematic diagram of an RF-ID system without a ferrite sintered body Schematic diagram of an RF-ID system with a sintered ferrite body Cross-sectional perspective view of NFC system equipped with sintered ferrite

The ferrite magnetic material of the present invention, from 46.7 to 48.7 mol% of _Fe 2 _O 3, _19.3~21.3 mol% of NiO, 10.05-12.05 mol% of CuO, 19.95 The compound (1-X) Co ₂ O ₃ .XFe ₂ O ₃ (provided that X is 0.48 to 0.54 mol) as at least a secondary component with respect to 100 parts by weight of the main component composed of 21.95 mol% of ZnO. ) 0.2 to 1.2 parts by weight and CuO 0.5 to 1.5 parts by weight. (Table 1) is a composition table studied for obtaining the ferrite magnetic material of the present invention, and (Table 2) shows characteristics for each composition. RunNo. Is a ferrite magnetic material within the scope of the present invention.

Hereinafter, the Run No. in (Table 1) and (Table 2). 1 to 30 will be described. RunNo. 1 to 5, when Fe ₂ O ₃ constituting the main component exceeds 48.7 mol%, the magnetic permeability is increased, but the Q value is greatly decreased, the communication distance at 13.56 MHz is shortened, and the magnetic permeability is increased. On the other hand, when the temperature change rate is less than 46.7 mol%, the magnetic permeability decreases, which is not preferable. RunNo. In 6-9, when NiO exceeds 21.3 mol%, the Q value is significantly reduced, and the communication distance is shortened. On the other hand, when NiO is less than 19.3 mol%, the temperature change rate of the magnetic permeability becomes small. Both the magnetic permeability and the Q value tend to decrease, and the communication distance becomes short. RunNo. 10-13, when CuO exceeds 12.05 mol%, both the magnetic permeability and the Q value tend to be small and the communication distance tends to be short. On the other hand, when CuO is less than 10.05 mol%, the magnetic permeability, Both Q values tend to decrease, both of which are not preferred. RunNo. In 14-17, when ZnO exceeds 21.95 mol%, the temperature change rate of the magnetic permeability decreases, but the Q value decreases remarkably, whereas when it becomes less than 19.95 mol%, the magnetic permeability increases. However, the temperature change rate of the magnetic permeability increases, the Q value decreases, and the communication distance becomes shorter.

RunNo. 26 to 30, when the fraction X of the compound (1-X) Co ₂ O ₃ .XFe ₂ O ₃ (provided that X is 0.48 to 0.54 mol) constituting the subcomponent exceeds 0.54 mol Both the magnetic permeability and the Q value tend to decrease, and the communication distance is shortened. On the other hand, when it is less than 0.48 mol, the magnetic permeability is decreased, which is not preferable. RunNo. 18-21, the addition amount of the compound (1-X) Co ₂ O ₃ .XFe ₂ O ₃ (provided that X is 0.48 to 0.54 mol) exceeds 100 parts by weight with respect to 100 parts by weight of the main component. Both the permeability and the Q value tend to decrease, and the communication distance becomes shorter. On the other hand, when the amount is less than 0.2 parts by weight, the Q value is greatly reduced and the communication distance is greatly shortened. . RunNo. In 22 to 25, when the amount of CuO added to 100 parts by weight of the main component exceeds 1.5 parts by weight, the Q value decreases, whereas when it is less than 0.5 parts by weight, both the magnetic permeability and the Q value tend to decrease. Therefore, the communication distance is shortened, which is not preferable.

In the ferrite magnetic material of the present invention, 46.7 to 48.7 mol% Fe ₂ O ₃ , 19.3 to 21.3 mol% NiO, 10.05 to 12.05 mol% CuO, 19 The main component comprising .95 to 21.95 mol% of ZnO is preferably a solid solution having a spinel crystal structure, and (1-X) Co ₂ O ₃ .XFe ₂ O ₃ (provided that X: 0.48 to 0.54 mol) is not a mixture of Co ₂ O ₃ and Fe ₂ O ₃ but a compound, and is preferably a solid solution having a spinel crystal structure. If the formation of the compound of Fe ₂ O ₃ and Co ₂ O ₃ is insufficient and a small amount of unreacted components remains, the ferrite material intended by the present invention cannot be obtained. Here, Co ₂ O ₃ constituting the subcomponent powder may be partially CoO, and a solid solution having the same spinel crystal structure as described above can be obtained. Become.

  FIG. 1 is a diagram showing a method for manufacturing a ferrite magnetic material. The flow of the method for producing a ferrite magnetic material of the present invention is shown in FIG. According to this, the ferrite magnetic material is prepared by mixing together the calcined product of the main component composed of the above composition, the calcined product of the subcomponent composed of the above composition, and CuO.

FIG. 2 is a powder X-ray diffraction pattern of the Fe ₂ O ₃ —Co ₂ O ₃ -based auxiliary component calcined product. FIG. 3 is a powder X-ray diffraction diagram of the ferrite magnetic material. The powder X-ray diffraction patterns of the calcined product of the subcomponent and the produced ferrite magnetic material are shown in FIGS. 2 and 3, respectively. According to FIG. 2, a diffraction peak of a Co ₂ O ₃ —Fe ₂ O ₄ spinel solid solution formed by calcining a mixture of subcomponents of Fe ₂ O ₃ and Co ₂ O ₃ was precipitated. Further, according to FIG. 3, the produced ferrite magnetic material was constituted by a crystal phase of a spinel solid solution of (Ni · Zn · Cu) Fe ₂ O ₄ . On the other hand, the Run No. in (Table 1) and (Table 2). 31-42 is as subcomponent _{(1-X) Co 2 O} 3 · XFe 2 O 3 ( where X: .48 to .54 moles) _Co 2 _{O 3} of the no calcination and _Fe 2 _{O 3} Applied as a mixture. Here, RunNo. The compositions of Nos. 31 to 42 are based on RunNo. 2, 4, 7, 8, 11, 12, 15, 16, 19, 20, 23, 24. As is clear from this, RunNo. The compositions of Nos. 31 to 42 were not preferable because both the magnetic permeability and the Q value tended to be lower than those with calcining, and the communication distance was short.

  The ferrite sintered body of the present invention is obtained by the ferrite magnetic material within the scope of the present invention described above, and its microstructure is less than a few μm (about 0.5 to 2 μm) with the crystal grains during grain growth. Preferably, the crystal grains in the progress of grain growth are solid solutions having a spinel crystal structure.

FIG. 4 is a diagram showing a microstructure with respect to the firing temperature of the ferrite fired body. In FIG. 3 by weight of 47.7 mol% Fe ₂ O ₃ , 20.30 mol% NiO, 11.05 mol% CuO, 20.90 mol% ZnO Firing when a molded body made of a ferrite magnetic material having a composition containing compound 0.49 Co ₂ O ₃ .0.51 Fe ₂ O ₃ 0.65 parts by weight and CuO 1.0 parts by weight is used. The relationship between temperature and microstructure was shown. The fine structure is obtained by photographing the fracture surface of each fired body with a scanning electron microscope. In FIG. 4, the ferrite fired body of the present invention has a fine structure fired at a firing temperature of 910 to 1000 ° C. That is, it consists of crystal grains in progress of grain growth and pores of several μm or less. In FIG. 4, the ferrite sintered body having a fine structure fired at a temperature of 880 ° C. has no growth of crystal grains causing the magnetic permeability, and therefore has a low magnetic permeability, a small Q value, and good communication performance. Cannot be obtained. Further, the mechanical strength is low, and defects such as cracks and chipping occur in the sintered ferrite body in the manufacturing assembly process. In addition, the sintered ferrite body having a fine structure fired at a temperature of 1020 ° C. has generated coarse crystal particles, is in a saturated state after the growth of crystal particles is completed, and has a high magnetic permeability. The value is remarkably lowered, and the conductivity in the high frequency band is increased, so that a sufficient magnetic flux focusing effect cannot be obtained, and good communication performance cannot be obtained in the RFID system or the NFC system. According to the powder X-ray diffraction pattern of the fired body fired at a temperature of 935 ° C., a single spinel solid solution of typical (Ni · Zn · Cu) Fe ₂ O ₄ similar to the ferrite magnetic material shown in FIG. A phase is formed, and thereby, the communication performance can be remarkably improved.

  An antenna module having good communication performance is realized by the RFID system or NFC system for portable terminals in which the sintered ferrite body of the present invention is inserted between the reader / writer exchange spiral antenna and the metal surface of the portable terminal housing cell. it can.

  FIG. 5 is a schematic view of an RF-ID system not equipped with a sintered ferrite body. FIG. 6 is a schematic view of an RF-ID system equipped with a sintered ferrite body.

  That is, FIGS. 5 and 6 are schematic views of the RF-ID system for portable terminals including the reader / writer exchange spiral antennas 52 and 62. In the RF-ID system of FIG. 5 configured by the mobile terminal housing cell 51 and the communication spiral antenna 52, the magnetic flux 53 entering the communication spiral antenna 52 is an eddy current generated on the metal surface of the mobile terminal housing cell 51. The communication function is greatly attenuated by cancellation by the magnetic flux 54 in the opposite direction. On the other hand, the RF-ID system for mobile terminals in FIG. 6 is one in which a sintered ferrite body 64 is inserted between the reader / writer exchange spiral antenna 62 and the metal surface of the mobile terminal housing cell 61. . As a result, the magnetic flux 63 entering the communication spiral antenna 62 is focused by the ferrite fired body 64, and the eddy current on the metal surface of the mobile terminal housing cell 61 is suppressed. The RF-ID system for portable terminals according to the present invention has a fine structure in which the fine structure of the ferrite fired body 64 is fired at a firing temperature of 910 to 1000 ° C. in the relationship between the firing temperature and the fine structure of FIG. It is. Thereby, an antenna module having good communication performance can be realized.

  Next, specific examples of the present invention will be described.

Example 1
In Example 1, the ferrite magnetic material of the present invention and the manufacturing method thereof will be described.

In Table 1, the RunNo. Is a ferrite magnetic material within the scope of the present invention. Moreover, FIG. 1 is a figure which shows the manufacturing method of a ferrite magnetic material. That is, as a starting raw material, iron oxide Fe ₂ O ₃ is 46.7 to 48.7 mol%, nickel oxide NiO is 19.3 to 21.3 mol%, copper oxide CuO is 10.05 to 12.05 mol%, Each zinc oxide ZnO was weighed using an electronic balance so that the ratio was 19.95 to 21.95 mol%, and then mixed for a predetermined time using a ball mill or the like. Mixing was performed wet, and zirconia spheres, stainless spheres, etc. were applied as the mixing medium. The slurry of the mixture was dried at a temperature of 110 to 130 ° C., then pulverized and calcined at a temperature of 800 to 910 ° C. to prepare a main component powder. A rotary kiln, a continuous tunnel furnace, a batch type box furnace, or the like can be applied to the calcination. The calcination conditions affect the reactivity of the main component powder, and strict control of process conditions is necessary to complete the formation of a solid solution with a spinel crystal structure in the final ferrite magnetic material. Become.

On the other hand, iron oxide Fe ₂ O ₃ has a ratio of 0.48 to 0.54 mol and cobalt oxide Co ₂ O ₃ has a ratio of 0.52 to 0.46 mol by the same method as the manufacturing method of the main component powder described above. A minor component powder was prepared. That is, a mixture of Fe ₂ O ₃ and Co ₂ O ₃ having a predetermined ratio was prepared, calcined at a temperature of 700 to 900 ° C., and pulverized to prepare an auxiliary component powder. FIG. 2 shows the powder X-ray diffraction pattern. Similar to the main component powder, the subcomponent powder is a solid solution having a spinel crystal structure formed by solid phase reaction of Fe ₂ O ₃ and Co ₂ O ₃ during calcination, and no unreacted component was confirmed. .

  Next, 0.2 to 1.2 parts by weight of the subcomponent powder, 0.5 to 1.5 parts by weight of copper oxide CuO as an additive, and electronic balance with respect to 100 parts by weight of the main component powder. Then, each was weighed, and then wet mixed and pulverized with an attraction mill, a ball mill or the like. Here, the mixing and pulverization controls the particle size distribution, average particle size, and BET specific surface area of the ferrite magnetic material that is the final powder, and is an important operation that influences the conditions and product performance of the post-process. In some cases, mixed pulverization may be performed for several tens of hours in order to obtain a target particle size. And after drying the slurry after mixing and pulverizing at the temperature of 110-130 degreeC, the ferrite magnetic material of this invention was obtained by crushing a dried lump.

The powder X-ray diffraction pattern of the produced ferrite magnetic material of the present invention is shown in FIG. That is, a solid-state reaction between the starting raw materials progressed during calcination to form a solid solution having a spinel crystal structure. The obtained ferrite magnetic material of the present invention had an average particle diameter of 0.5 to 1.6 μm according to the particle size distribution measurement by the laser diffraction scattering method. Moreover, according to the specific surface area measurement of BET by a nitrogen gas adsorption method, it had a value of 3.000-5.500 m ² / g.

As described above, the ferrite magnetic material of the present invention has a main component powder composed of Fe ₂ O ₃ , NiO, CuO, ZnO whose molar ratio is limited in the manufacturing method thereof, and Co ₂ O ₃ whose molar ratio is limited. , Fe ₂ O ₃ subcomponent powders are calcined and reacted, and at least one of the main component and subcomponent is a solid solution having a spinel crystal structure.

(Example 2)
In Example 2, a method for manufacturing a ferrite sintered body made of a ferrite magnetic material manufactured based on the composition table of (Table 1) and evaluation of magnetic properties such as magnetic permeability and Q value will be described.

  Based on the composition table of (Table 1), 4.0 to 6.0 parts by weight of polyvinyl butyral resin with respect to 100 parts by weight of the ferrite magnetic material produced by the method described in Example 1, phthalic acid After blending 3.5 to 6.0 parts by weight of an ester plasticizer and 40 to 60 parts by weight of an organic solvent, the mixture was mixed by a dedicated mill to prepare a slurry. The viscosity of the produced slurry was 1500-2500 Pa · sec at 20 ° C., and had an appropriate viscosity for sheet molding. The weights of the polyvinyl butyral resin, the phthalate ester plasticizer, and the organic solvent are the lot-to-lot fluctuations of the starting raw materials, the fluctuation of the solid-phase reaction state in the calcining, the fluctuation of the average particle diameter after mixing and grinding, and It can be appropriately adjusted within the above-mentioned range depending on the set thickness of the molded sheet in the next step.

  Next, a slurry made of a ferrite magnetic material was formed on a PET film to produce a green sheet having a thickness of 50 to 300 μm. That is, while supplying the slurry whose viscosity was adjusted to the coating machine, the gap between the rollers and the line speed were adjusted to form a film on the PET film, dried, and then rolled up to produce a green sheet. The thickness of the green sheet can be controlled to 50 to 300 μm by adjusting the gap between the rollers. Moreover, the drying temperature which affects the lamination | stacking adhesiveness of green sheets was adjusted to 60-90 degreeC. The line speed needs to be adjusted according to the surface state and dry state of the green sheet to be produced, and is controlled within the range of 0.5 to 2.0 m / min. When the balance between the slurry viscosity, the thickness of the green sheet, the line speed, and the drying temperature is deteriorated, cracks are generated on the surface of the produced green sheet, and thus appropriate control is required.

  Next, in the laminate manufacturing process, the green sheets were laminated in a predetermined number of layers by a laminator. That is, the green sheet formed on the PET film was laminated in 2 to 6 layers by heating roller pressure bonding of a laminating machine to produce a laminate having a predetermined thickness. The surface temperature of the heating roller was controlled to 100 to 120 ° C., which was higher than the glass transition temperature of the polyvinyl butyral resin, to ensure good lamination adhesion.

  Next, in the cutting step, the laminated green sheets were cut into a predetermined shape. That is, the laminated green sheet was punched and cut using a special mold designed to fit the shape of the RFID or NFC contact spiral antenna to produce a molded body having a predetermined shape and thickness. Since the green sheet has good lamination adhesion, problems such as delamination did not occur in this process. In the case of a product number that does not require lamination due to the type configuration of the final product, the formed green sheet is cut into a predetermined shape without going through the lamination process.

  Next, a compact having a predetermined shape was packed in a sheath, and then degreased and fired to prepare a ferrite fired body. The sintered ferrite body had a thickness of 30 to 250 μm. That is, after a compact made of a ferrite magnetic material was packed on an alumina thin plate, degreasing was carried out to burn a polyvinyl butyral resin and a phthalate ester plasticizer. The degreasing conditions are 350 to 600 ° C., and in order to achieve good degreasing, it is necessary to balance the amount of air driven into the furnace and the exhaust amount of the exhaust gas blower. Further, a rapid temperature rise needs to be avoided because it causes cracks in the final fired body. Next, it fired at the maximum temperature of 930 degreeC (910-1000 degreeC is preferable) with this baking furnace, and produced the ferrite sintered compact. Degreasing and main firing were carried out in a continuous tunnel furnace, batch-type box furnace, belt-type tunnel furnace or the like. Usually, degreasing and main baking are continuously performed in the same furnace, but degreasing and main baking may be performed in separate furnaces. Note that the maximum firing temperature can be appropriately adjusted depending on the target product number in the final product type configuration. Further, appropriate adjustment is required depending on the structure of the firing furnace, the amount of the fired body, and the like.

FIG. 4 shows an example of a fracture surface of a sintered ferrite body taken with a scanning electron microscope. The ferrite sintered body of this example, which was fired at the maximum temperature of 930 ° C., was formed from crystal grains in progress of grain growth and pores of several μm or less. Further, according to the powder X-ray diffraction of the ferrite sintered body of the present embodiment, to form a main crystalline phase (Ni · Zn · Cu) single phase is a spinel solid solution of Fe ₂ O ₄ system.

  Next, the magnetic permeability, Q value (reciprocal of loss coefficient), and temperature change rate of magnetic permeability were measured for each sintered ferrite body produced based on the composition table of (Table 1). First, in order to protect the shape of the ferrite fired body having a thickness of 100 to 110 μm, a water-resistant tape was applied to both surfaces thereof, and then subjected to a break process in order to give the fired body flexibility. Then, a toroidal body having an outer diameter of 22 mm and an inner diameter of 13 mm was produced using a pinnacle mold. A copper wire having a diameter of 0.25 mm was spirally wound around the toroidal body for 20 turns to obtain a specimen for measuring magnetic properties. Using an LCR meter manufactured by Hewlett-Packard Company, the L value (reactance) and Q value at 13.56 MHz were measured, and converted into the L value to obtain the magnetic permeability. The temperature change rate of the magnetic permeability was obtained by measuring the L value in the temperature range of −40 ° C. to 100 ° C. by connecting the specimen left in the thermostat and the LCR meter with a dedicated cable. After converting the L value into the magnetic permeability, the rate of change of 20 to 100 ° C. was determined based on the magnetic permeability of 20 ° C. The results of a series of magnetic properties are shown in (Table 2).

  According to this, RunNo. The ferrite sintered body made of a ferrite magnetic material within the scope of the present invention marked with * has a high product of permeability and Q value (μ × Q), which is an index of communication performance, as high as 10,000 or more. The rate of temperature change was stable.

  As described above, the sintered ferrite body of the present invention is made of the ferrite magnetic material produced by the manufacturing method described in Example 1, and the crystal grains, which are solid solutions having a spinel crystal structure, are in the process of grain growth. It has a certain fine structure. And it had a favorable magnetic characteristic, and the product of the magnetic permeability in 13.56 MHz and Q value had 10,000 or more.

(Example 3)
The ferrite sintered body made of the ferrite magnetic material of the present invention is mainly applied to obtain good communication performance in an RFID module that performs data communication without contact or an antenna module in an NFC system.

  FIG. 7 is a cross-sectional perspective view of an NFC system equipped with a ferrite sintered body. According to this, the sintered ferrite body 74 is inserted between the NFC antenna 73 and the NFC system casing cell 72.

  The communication function was measured with a configuration similar to FIG. That is, the ferrite fired body having a thickness of 100 to 110 μm produced in Example 2 based on the composition table of (Table 1) was bonded with water-resistant tape on both sides in order to protect the shape, and then flexible. A break was made to give it a character. A pinnacle mold was used to punch out a rectangle having a size of 30 mm × 25 mm to obtain a test piece for communication function measurement. A copper plate that looks like a casing cell was attached to one side of the specimen, and a spiral antenna for an NFC system was attached to the other side to form a measurement tag. An antenna module was configured between the tag and the NFC reader / writer, and the communication distance at a resonance frequency of 13.56 MHz was measured. The measurement results are shown in (Table 2).

  According to this, RunNo. The antenna module composed of a ferrite sintered body made of a ferrite magnetic material within the scope of the present invention marked with * has a communication distance of 110 mm or more, and the permeability and Q value measured in Example 2 There was a positive correlation with the product of (μ × Q).

  As described above, the antenna module of the present invention is composed of a sintered ferrite body having a product of high magnetic permeability and Q value (μ × Q), and an RFID system or NFC system having good communication performance is provided. realizable.

(Comparative example)
In the comparative example, the subcomponent powder having a ratio of 0.51 mol of iron oxide Fe ₂ O _{3 and} 0.49 mol of cobalt oxide Co ₂ O ₃ is not a solid solution having a spinel crystal structure but a simple mixture. Describe the case.

That is, based on the composition table shown in (Table 3), the RunNo. Ferrite magnetic materials corresponding to the compositions of 31 to 42 were produced. In particular, the difference from Example 1 was that spinel was formed by a solid-state reaction by calcining with respect to a subcomponent powder having a ratio of 0.51 mol of iron oxide Fe ₂ O _{3 and} 0.49 mol of cobalt oxide Co ₂ O _3. It was applied as a mere mixture without forming a solid solution of the type crystal structure. That is, in RunNo. Ferrite magnetic materials having the compositions of 31 to 42 are listed in Run No. of (Table 1). It has the same composition as 2, 4, 7, 8, 11, 12, 15, 16, 19, 20, 23, 24, and the auxiliary component is a simple mixture. Next, the produced RunNo. Using a ferrite magnetic material having a composition of 31 to 42, a ferrite fired body was produced by the same manufacturing method as in Example 2, and then its magnetic properties, magnetic permeability, Q value (reciprocal of loss factor), and magnetic permeability The temperature change rate of was measured.

  A series of magnetic characteristics results are shown in Run No. of (Table 4). 31 to 42. And, the composition is the same, but a solid solution having a spinel crystal structure is formed by a solid-phase reaction by calcination (Table 2). 2, 4, 7, 8, 11, 12, 15, 16, 19, 20, 23, 24. According to this, the ferrite fired body of this comparative example in which the subcomponent was applied in the form of a mixture had a particularly lower Q value than the ferrite fired body of Example 2 in which the subcomponent was applied as a solid solution having a spinel crystal structure. Therefore, the product (μ × Q) of permeability and Q value, which is an index of communication performance, is low, and is generally about 10,000 or less.

  Next, in the same manner as in Example 3, RunNo. A prototype tag for measurement was made using each of the sintered ferrite bodies made of 31 to 42 ferrite magnetic material, and the communication distance with the reader / writer was measured at a resonance frequency of 13.56 MHz. The results are shown in (Table 4). According to this, it is linked with the product of permeability and Q value (μ × Q). Compared with the results of 2, 4, 7, 8, 11, 12, 15, 16, 19, 20, 23, and 24, the communication distance was 110 mm or shorter.

As described above, in the magnetic material of the present invention, when the form of the subcomponent powder composed of Fe ₂ O ₃ and Co ₂ O ₃ is not a solid solution having a spinel crystal structure but a simple mixture, the permeability and Q value are The product (μ × Q) is small, the communication distance is shortened, and the intended result of the present invention cannot be obtained.

  The ferrite magnetic material and the manufacturing method thereof, the ferrite fired body using the ferrite magnetic material, and the antenna module according to the present invention specify the composition of the ferrite magnetic material, the manufacturing method thereof, and the form of the ferrite fired body thereby, and have good communication performance. Therefore, the present invention is particularly useful for an RFID system for portable terminals and an NFC system comprising a reader / writer exchange spiral antenna.

51, 61 Mobile terminal housing cell 52, 62 Communication spiral antenna 53, 63 Magnetic flux entering the communication spiral antenna 54 Magnetic flux in the opposite direction due to eddy current 64 Ferrite fired body 72 NFC system housing cell 73 NFC antenna 74 Ferrite firing body

Claims (7)

46.7 to 48.7 mol% of _Fe 2 _O 3, _19.3~21.3 mol% of NiO, 10.05-12.05 mol% of CuO, 19.95 to 21.95 mol% of ZnO The compound (1-X) Co ₂ O ₃ .XFe ₂ O ₃ (where X is 0.48 to 0.54 mol) as at least a subcomponent is added to 0.2 to 1.100 parts by weight of the main component. A ferrite magnetic material comprising 2 parts by weight and 0.5 to 1.5 parts by weight of CuO. 46.7 to 48.7 mol% of _Fe 2 _O 3, _19.3~21.3 mol% of NiO, 10.05-12.05 mol% of CuO, 19.95 to 21.95 mol% of ZnO The compound (1-X) Co ₂ O ₃ .XFe ₂ O ₃ (where X is 0.48 to 0.54 mol) as at least a subcomponent is added to 0.2 to 1.100 parts by weight of the main component. 2. The composition according to claim 1, comprising 2 parts by weight and 0.5 to 1.5 parts by weight of CuO, wherein at least one of the main component and the subcomponent is a solid solution having a spinel crystal structure. The ferrite magnetic material described. 46.7 to 48.7 mol% of _Fe 2 _O 3, _19.3~21.3 mol% of NiO, 10.05-12.05 mol% of CuO, 19.95 to 21.95 mol% of ZnO A step of preparing a main component powder by calcining a mixture comprising a predetermined temperature, XFe ₂ O ₃ and (1-X) Co ₂ O ₃ (where X is 0.48 to 0.54 mol). A step of producing a subcomponent powder by calcining the mixture at a predetermined temperature, and 0.2 to 1.2 parts by weight of the subcomponent powder and 0.5% of CuO with respect to 100 parts by weight of the main component powder. A method for producing a ferrite magnetic material, wherein the step of mixing after mixing 1.5 parts by weight is performed sequentially. 46.7 to 48.7 mol% of _Fe 2 _O 3, _19.3~21.3 mol% of NiO, 10.05-12.05 mol% of CuO, 19.95 to 21.95 mol% of ZnO A step of preparing a main component powder by calcining a mixture comprising a predetermined temperature, XFe ₂ O ₃ and (1-X) Co ₂ O ₃ (where X is 0.48 to 0.54 mol). A step of producing a subcomponent powder by calcining the mixture at a predetermined temperature, and 0.2 to 1.2 parts by weight of the subcomponent powder and 0.5% of CuO with respect to 100 parts by weight of the main component powder. 4. The method of claim 3, further comprising a step of mixing after mixing 1.5 parts by weight, wherein at least one of the main component powder and the subcomponent powder is a solid solution having a spinel crystal structure. The manufacturing method of the ferrite magnetic material of description. 46.7 to 48.7 mol% of _Fe 2 _O 3, _19.3~21.3 mol% of NiO, 10.05-12.05 mol% of CuO, 19.95 to 21.95 mol% of ZnO The compound (1-X) Co ₂ O ₃ .XFe ₂ O ₃ (where X is 0.48 to 0.54 mol) as at least a subcomponent is added to 0.2 to 1.100 parts by weight of the main component. 2 parts by weight, each containing 0.5 to 1.5 parts by weight of CuO,
A ferrite sintered body comprising a fine structure having crystal grains in progress of grain growth and pores of several μm or less. 46.7 to 48.7 mol% of _Fe 2 _O 3, _19.3~21.3 mol% of NiO, 10.05-12.05 mol% of CuO, 19.95 to 21.95 mol% of ZnO The compound (1-X) Co ₂ O ₃ .XFe ₂ O ₃ (where X is 0.48 to 0.54 mol) as at least a subcomponent is added to 0.2 to 1.100 parts by weight of the main component. 6. The ferrite sintered body according to claim 5, wherein the crystal grains containing 2 parts by weight and 0.5 to 1.5 parts by weight of CuO are solid solutions having a spinel crystal structure. In the antenna system in the RFID system or NFC system that performs data communication without contact, the magnetic member installed in the antenna module is formed of the ferrite sintered body according to any one of claims 5 and 6. An antenna module characterized by