JP2007258880A - Non-receiprocal circuit element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-receiprocal circuit element in which insertion loss characteristics are adjusted easily even when the insertion loss characteristics deviate from a standard. <P>SOLUTION: In the non-receiprocal circuit element; a soft magnetic substrate is abutted against the intersection of a plurality of central conductors arranged to cross each other under electrically insulated state, and a permanent magnet is provided for applying a DC magnetic field to the soft magnetic substrate. The permanent magnet is a sintered ferrite magnet where a ferrite phase having a hexagonal structure composes a main phase. When the composition rate of metal elements composing the main phase is represented by a composition formula (1): La<SB>x</SB>Ca<SB>m</SB>α<SB>1-x-m</SB>(Fe<SB>12-y</SB>Co<SB>y</SB>)<SB>z</SB>, α is one kind or two kinds of Ba and Sr, x and m are values in a region surrounded by (0.37, 0.10), (0.60, 0.30), (0.54, 0.45) and (0.37, 0.37) on the (x, m) coordinate shown in Fig. 4, and following relations are satisfied; 1.15≤x/yz≤1.95 and 9.2≤12z≤11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to non-reciprocal circuit elements such as isolators and circulators.

Non-reciprocal circuit elements such as isolators and circulators are used in mobile wireless devices such as mobile phones. This type of non-reciprocal circuit device includes a permanent magnet that abuts a soft magnetic base on the crossing portions of a plurality of central conductors arranged in an electrically insulated state and applies a DC magnetic field to the soft magnetic base. ing. In addition, the nonreciprocal circuit device includes electrical components such as a matching capacitor and a termination resistor.
This type of nonreciprocal circuit device is required to be as small or thin as possible because of its marketability. In response to this requirement, Patent Document 1 discloses that the nonreciprocal circuit element can be reduced in size and thickness by using a specific sintered ferrite magnet as a permanent magnet that applies a DC magnetic field to a soft magnetic substrate. Rare earth ferrite sintered magnet, comprising _{(A 1-x R x)} O · n [(Fe 1-y M y) 2 O 3] ( atomic ratio) (A is Sr and / or Ba, R is Y And at least one element selected from the group consisting of Co, Mn, Ni and Zn), 0.01 ≦ x ≦ 0.4, [x / (2.6n)] ≦ y ≦ [x / (1.6n)], having a basic composition represented by 5 ≦ n ≦ 6, and substantially having a magnetoplumbite type crystal structure. Since the sintered ferrite magnet disclosed in Patent Document 1 has high magnetic characteristics, a predetermined DC magnetic field can be applied to the soft magnetic substrate even if the thickness is reduced. As a result, the nonreciprocal circuit device can be reduced in size and thickness.

JP 2000-223911 A

New problems have been raised by reducing the size and thickness of non-reciprocal circuit devices. This is because the ratio of the characteristics of the assembled nonreciprocal circuit element, specifically, the insertion loss characteristics deviates from a predetermined standard. It can be understood that each component constituting the nonreciprocal circuit element has been downsized, and thus the degree to which the characteristic variation of each component is reflected in the final product has increased.
Therefore, an object of the present invention is to provide a non-reciprocal circuit device that can easily adjust the insertion loss characteristic to the standard even when the insertion loss characteristic deviates from the standard.

When adjusting the insertion loss of the non-reciprocal circuit element, it is not realistic to replace each component with an appropriate one because it has already been completed as a product. Accordingly, the present inventors have examined the adjustment of insertion loss characteristics by changing the characteristics of a permanent magnet that applies a DC magnetic field to a soft magnetic substrate.
Usually, the non-reciprocal circuit element magnetizes a permanent magnet (first magnetization) after assembling each component. The magnetization condition is set so that the insertion loss characteristic conforms to the standard. However, for the reason described above, the actual condition may deviate from the standard. At this time, the insertion loss characteristic can be changed by changing the magnetic characteristic of the permanent magnet. For example, when the peak of insertion loss is lower than a desired frequency, the peak of insertion loss can be shifted to the high frequency side by increasing the magnetic characteristics of the permanent magnet. In order to increase the magnetic characteristics of the permanent magnet, magnetization (magnetization) may be performed again with a magnetic field stronger than the previous magnetization. Conversely, when the peak of the insertion loss is at a position higher than the desired frequency, the peak of the insertion loss can be shifted to the low frequency side by lowering the magnetic characteristics of the permanent magnet. In order to lower the magnetic characteristics of the permanent magnet, the magnetization (demagnetization) may be performed again with a magnetic field weaker than the previous magnetization. As described above, even after the magnetization is once performed, the insertion loss characteristic can be adjusted by changing the magnetic field intensity and magnetizing the permanent magnet again.

  In order to change the insertion loss characteristic by magnetizing, as a precondition, the permanent magnet must be previously magnetized so that the magnet can be magnetized. That is, it is necessary to perform the previous magnetization with a magnetic field having a strength lower than that of saturation magnetization. The difference between the saturation point of the permanent magnet obtained by saturation magnetization and the magnetic characteristics obtained by the previous magnetization is referred to as a margin in the present specification. When attempting to change the insertion loss characteristics by demagnetizing, it is not necessary to provide a margin for the magnetic characteristics in the previous magnetization, but whether to increase the magnetism or demagnetization is necessary. Since the magnetism is unknown, it is necessary to provide a margin for the magnetic characteristics by the previous magnetization.

The present inventor has studied a ferrite permanent magnet that can provide such a margin, and when it has a specific composition, by obtaining a larger margin, the insertion loss characteristic as a non-reciprocal circuit element can be reduced from the standard. It has been found that the insertion loss characteristic can be easily adjusted even if it is considerably deviated. That is, the present invention provides a non-reciprocal circuit device in which a soft magnetic substrate is brought into contact with the intersecting portions of a plurality of central conductors arranged in an electrically insulated state and a permanent magnet for applying a DC magnetic field to the soft magnetic substrate is provided. In this permanent magnet, the ferrite phase having a hexagonal crystal structure is the main phase, and the composition ratio of the metal elements constituting the main phase is represented by the composition formula (1): La _x Cam _m α _1-xm (Fe _12−y Co _y ) When represented by _z , α is one or two of Ba and Sr, and x and m are (0.37,0.10) in the (x, m) coordinates shown in FIG. ), (0.60, 0.30), (0.54, 0.45), and a value within the region surrounded by (0.37, 0.37), 1.15 ≦ x / yz ≦ 1.95 9.2 ≦ 12z ≦ 11, a ferrite sintered magnet having a composition represented by 9.2 ≦ 12z ≦ 11 It is a road element.
In the present invention, m is preferably 0.2 to 0.45, and preferably 1.25 ≦ x / yz ≦ 1.85.

  According to the present invention, it is possible to provide a non-reciprocal circuit device that can easily adjust the insertion loss characteristic to the standard even when the insertion loss characteristic deviates from the standard. Therefore, the probability that the insertion loss characteristic can be adjusted to the characteristic within the standard is increased, and the product yield of the non-reciprocal circuit element can be improved.

FIG. 1 is an exploded perspective view showing an embodiment of a non-reciprocal circuit device according to the present invention.
A nonreciprocal circuit device 1 shown in FIG. 1 is an isolator and includes a magnetic rotor 2, a permanent magnet 7, and a case 9.

  The case 9 includes a case main body 91 and a cover 92 that closes the opening of the case main body 91. The case main body 91 includes a magnetic metal material having electrical conductivity and an electrically insulating resin material, and is formed in a box shape having an open top. The side wall 11 of the case body 91 is made of an electrically insulating resin material, and external terminals 15 that are electrically connected to the inside and outside of the case body 91 are formed on the side wall 11. The bottom surface 13 of the case body 91 is made of a magnetic metal material and serves as a ground G. The case main body 91 accommodates the magnetic rotor 2, the permanent magnet 7, the matching capacitors C1 to C3, and the termination resistor R. The cover 92 is made of a magnetic metal material having electrical conductivity, overlaps with the permanent magnet 7, is combined with the case body 91 so as to close the opening of the case body 91, and is magnetically coupled to form a yoke.

The magnetic rotor 2 includes a center electrode 3 including a plurality of center conductors and a soft magnetic substrate 4.
The soft magnetic substrate 4 is preferably a soft magnetic material such as yttrium / iron / garnet (YIG). The soft magnetic substrate 4 has a square shape with a side of several mm and is formed in a flat plate shape with a thickness of about 0.1 to 1.0 mm.
The center electrode 3 includes first to third center conductors 31 to 33, and is formed of, for example, a conductor plate obtained by punching a copper plate having a thickness of about 30 to 50 μm. The first to third central conductors 31 to 33 are branched from three sides of a substantially rectangular ground portion 30 in contact with the lower surface of the soft magnetic substrate 4 in the drawing. The first to third center conductors 31 to 33 are sequentially bent while being insulated from each other so as to intersect each other at a predetermined angle on the main surface of the soft magnetic substrate 4.

  The tips of the first to third central conductors 31 to 33 are formed so as to protrude from the side edges of the upper surface of the soft magnetic base 4 and connect terminal portions 331 to 331 for the matching capacitors C1, C2, C3, the terminating resistor R, and the like. 333. First, the connection terminal portions 331 and 332 are in contact with the external electrodes of the matching capacitors C1 and C2, respectively. The connection terminal portion 331 is disposed in contact with the matching capacitor C3 and the termination resistor R.

The permanent magnet 7 is formed in a flat plate shape and is disposed so as to overlap the magnetic rotor 2 and applies a DC magnetic field to the magnetic rotor 2.
Matching capacitors C1 to C3 and a terminating resistor R are disposed on the bottom surface 13 of the case body 91, and the magnetic rotor 2 is disposed in a region surrounded by them. The ground portion 30 of the center electrode 3 is electrically connected to the bottom surface 13 (ground G) of the case body 91. Further, the cover 92 closes the opening of the case main body 91 in a state where the permanent magnet 7 is disposed on the magnetic rotor 2.

Now, non-reciprocal circuit device 1, the permanent magnet 7, a ferrite phase forms the main phase having a hexagonal structure, the proportions of the metal elements constituting the main phase, the composition formula _{(1): La x Ca m} α When expressed by _1-xm (Fe _12-y Co _y ) _z , α is one or two of Ba and Sr, and x and m are (x, m) coordinates shown in FIG. 0.37, 0.10), (0.60, 0.30), (0.54, 0.45), and a value within the region surrounded by (0.37, 0.37), 1.15 ≦ A sintered ferrite magnet having a composition represented by x / yz ≦ 1.95 and 9.2 ≦ 12z ≦ 11. Hereinafter, this ferrite sintered magnet will be described in detail.

The M-type ferrite magnetic material disclosed in Patent Documents 2 and 3 has a composition formula of Sr _1-x R _x (Fe _12-y Co _y ) _z O ₁₉ with 0.04 ≦ x ≦ 0.9, 0 0.04 ≦ y ≦ 0.5 is disclosed. Note that R is typically La. However, for example, as shown in FIG. 1 of Patent Document 2, in order to obtain a high residual magnetic flux density (Br) and a coercive force (HcJ), in the above composition formula, x = y = 0.2 to 0.4. Is necessary. Even if the amounts of x and y are increased, R and Co cannot be substituted and dissolved in the hexagonal ferrite phase. For example, orthoferrite containing the element R is generated and the magnetic properties are deteriorated. Therefore, there has been a limit to the improvement of magnetic characteristics by replacing R and Co with hexagonal ferrite phases and increasing the amount of solid solution.

JP-A-11-154604 JP 2000-195715 A

  The present inventors can increase the solid solution amount (or substitution amount) of R, particularly La, in the hexagonal ferrite phase when Ca is co-existing with one or two of Ba and Sr at the A site. Moreover, it was found that the margin can be increased by obtaining high magnetic characteristics. This hexagonal ferrite is referred to as La-based hexagonal ferrite because the ratio of La at the A site is generally higher than that of one or two of Ba and Sr, which are other A site constituent elements, and Ca. Can do.

  As described above, the present invention has a large proportion of La at the so-called A site and can be called La-based ferrite. However, since the amount of La in the hexagonal ferrite cannot be ensured if the ratio of one or two of Ba and Sr, which are other constituent elements of the A site, and Ca is too small, the amount of La in the hexagonal ferrite cannot be secured. The effect will not be obtained.

  In the present invention, if La (x) is small, the effect of improving the magnetic characteristics cannot be obtained sufficiently. The sintered ferrite magnet of the present invention is characterized in that the amount of La solid solution in the ferrite phase can be increased. However, if the amount is too large, the solid solution cannot be completely dissolved, which causes generation of a nonmagnetic phase such as orthoferrite. .

In the present invention, if the amount of Ca (m) is small, the solid solution amount of La cannot be increased sufficiently. However, if the amount of Ca is too large, the ratio of the sum of one or two of La, Ba, and Sr at the A site is lowered. If La is reduced, the effect of La substitution is reduced, and 1 of Ba and Sr is reduced. When seeds or two kinds are completely zero, α-Fe ₂ O ₃ is easily generated.

In the present invention, Fe is a basic element constituting ferrite. When Fe is too small, the A site becomes surplus, and the non-magnetic grain boundary component is unnecessarily increased from the main phase and the saturation magnetization is lowered. Further, when Fe is too large, the _alpha-Fe 2 _{O 3} thus generated.

  In the present invention, Co has an effect of improving magnetic properties by substituting part of Fe of the M-type ferrite phase. If the amount of Co is small, the effect of improving the magnetic properties by replacing a part of Fe with Co cannot be obtained sufficiently. On the other hand, if there is too much Co, the optimum point of charge balance with La will be exceeded, and the magnetic properties will deteriorate.

On the premise of the action and effect of each element as described above, the ferrite magnetic material of the present invention has a hexagonal ferrite phase as the main phase, and the composition ratio of the metal elements constituting the main phase is expressed by the composition formula ( 1): when represented by _{La x Ca m α 1-x} -m (Fe 12-y Co y) z, x, m is the (x, m) coordinates shown in FIG. 4, (0.37, 0.10), (0.60, 0.30), (0.54, 0.45) and (0.37, 0.37), the value within the region, 1.15 ≦ x / yz ≦ 1.95 and 9.2 ≦ 12z ≦ 11.

  The compositional formula (1) is based on a general formula of M-type ferrite well known among those skilled in the art, and indicates a so-called main phase composition. That is, the element constituting the composition formula (1) is usually an element constituting the main phase. However, among the elements constituting the composition formula (1), Ca is an element that can also be used as an auxiliary component. For example, when analyzing the amount of constituent elements of a ferrite magnetic material made of a sintered body, even if it is an element common to both the main phase and the subcomponent, the analysis results include either the main phase or the subcomponent. I can't figure out if it is included. Therefore, in the present invention, the amount of Ca in the composition formula (1) is an amount including both the main phase and the subcomponent.

In the present invention, the ratio of La to Co (La / Co) is also important in order to obtain a large margin with high magnetic characteristics. According to Patent Documents 2 and 3, La / Co is ideally 1. In other words, since a part of Sr ²⁺ of the M-type ferrite represented by Sr ²⁺ Fe ³⁺ ₁₂ O ₁₉ is replaced with La ³⁺ and a part of Fe ³⁺ is replaced with Co ²⁺ , the ratio of La to Co is set to 1. Is ideal. However, the present inventors have found that in the La-based hexagonal ferrite according to the present invention, the coercive force can be improved without impairing the residual magnetic flux density in a predetermined range where La / Co exceeds 1. In the present invention, a large margin can be obtained by setting La / Co, that is, x / yz in the range of 1.15 to 1.95. Preferred x / yz is 1.25 to 1.85, and more preferred x / yz is 1.35 to 1.75.

In the composition formula (1), if z is too small, the A site becomes surplus, the non-magnetic grain boundary component is unnecessarily increased from the main phase, and the saturation magnetization is lowered. On the other hand, if z is too large, the nonmagnetic α-Fe ₂ O ₃ phase or the soft magnetic spinel ferrite phase containing Co increases, so the residual magnetic flux density (Br) decreases. Here, the total amount of Fe and Co is represented by 12z from the composition formula (1). As shown in Examples described later, the present invention can obtain a large margin by specifying 12z which is the total amount of Fe and Co. That is, the present invention sets 9.2 ≦ 12z ≦ 11. A preferable value of 12z is 9.4 ≦ 12z ≦ 10.8, and a more preferable value of 12z is 9.7 ≦ 12z ≦ 10.5.

The composition formula (1) shows the composition ratio of the total metal elements of La, Ca, α, Fe, and Co. When oxygen O is included, La _x Cam _m α _1-x can be represented by _{-m (Fe 12-y Co y} ) z O 19. In the present invention, a sintered ferrite magnet in which the ratio of the hexagonal M-type ferrite phase (M phase) represented by this composition formula is 95% or more is used. Here, the number of atoms of oxygen O is 19, which is the chemistry of oxygen O when Co is divalent, Fe and La are trivalent, and x = y and z = 1. The stoichiometric composition ratio is shown. The number of oxygen O atoms varies depending on the values of x, y, and z. For example, when the firing atmosphere is a reducing atmosphere, oxygen O deficiency (vacancy) may occur. Further, Fe is usually trivalent in the M-type ferrite phase, but this may change to divalent. In addition, Co may have a valence change, and La may also have a valence other than trivalence, which changes the ratio of oxygen O to metal elements. In the examples described later, the number of oxygen O atoms is displayed as 19 regardless of the values of x, y, and z. However, the actual number of oxygen O atoms shows a slightly deviated value. Of course, the present invention includes such a case.

  In the sintered ferrite magnet used in the present invention, on the premise that a predetermined amount of La constituting the A site is contained, a part thereof is made of other rare earth elements (Ce, Pr, Nd, Pm, Eu, Gd, Tb). , Dy, Ho, Er, Tm, Yb, Lu). In the ferrite sintered magnet of the present invention, the element α is one or two of Ba and Sr.

The composition of the sintered ferrite magnet according to the present invention can be measured by fluorescent X-ray quantitative analysis or the like. The content of each element specified in the present invention can be specified by this analysis value. The presence of the M phase in the sintered ferrite magnet of the present invention can be confirmed by X-ray diffraction, electron beam diffraction, or the like. Specifically, in the present invention, the abundance ratio (mol%) of the M phase was determined by X-ray diffraction under the following conditions. The abundance ratio of the M phase is calculated by mixing powder samples of M-type ferrite, orthoferrite, hematite, and spinel at a predetermined ratio, and comparing and calculating from their X-ray diffraction intensities (examples described later). But the same).
X-ray generator: 3kW
Tube voltage: 45kV
Tube current: 40 mA
Sampling width: 0.02 deg
Scanning speed: 4.00 deg / min
Divergence slit: 1.00 deg
Scattering slit: 1.00 deg
Receiving slit: 0.30mm

The ferrite sintered magnet according to the present invention can contain a Si component and a Ca component as subcomponents. The Si component and the Ca component as subcomponents are intended to improve sinterability, control magnetic properties, adjust the crystal grain size of the sintered body, and the like. As described above, Ca is an element included also as a main phase, and the description here is only for the Ca component as a subcomponent. Note that the Si component and the Ca component as subcomponents exist exclusively at the grain boundaries.
It is preferable to add SiO ₂ as the Si component and CaCO ₃ as the Ca component. The addition amount of the Si component is preferably 0 (not included) to 1.35 wt% in terms of SiO ₂ , more preferably 0.05 to 0.90 wt%, and still more preferably 0.05 to 0.75 wt%. is there.

  The present invention contains Ca as a main component constituting the ferrite phase which is the main phase. Therefore, when the Ca component is contained as a subcomponent, for example, the amount of Ca analyzed from the sintered body is the total amount of the main phase (sometimes referred to as the main component) and the subcomponent. Therefore, as described above, when the Ca component is used as the subcomponent, the amount of Ca in the composition formula (1) includes the subcomponent. Since the range of Ca is specified based on the composition analyzed after sintering, it goes without saying that the range of Ca is also applied when no Ca component is used as a subcomponent.

The ferrite magnetic material of the present invention can contain Al ₂ O ₃ and / or Cr ₂ O ₃ as subcomponents. Al ₂ O ₃ and / or Cr ₂ O ₃ has an effect of improving the coercive force. However, since Al ₂ O ₃ and / or Cr ₂ O ₃ tends to reduce the residual magnetic flux density, it is preferably set to 3.0 wt% or less. In order to sufficiently exhibit the effect of the _Al 2 _{O 3} and / or _Cr 2 _{O 3} addition, it is preferred to limit its content to 0.1 wt% or more.

The ferrite magnetic material of the present invention may contain B ₂ O ₃ as a subcomponent. By containing B ₂ O ₃ , the calcination temperature and the sintering temperature can be lowered, which is advantageous in production. The content of B ₂ O ₃ is preferably 0.5 wt% or less of the entire ferrite magnetic material. When the content of B ₂ O ₃ is too large, the saturation magnetization becomes low.

The ferrite magnetic material of the present invention preferably contains no alkali metal element such as Na, K, Rb, etc., but may contain it as an impurity. When these are converted into oxides such as Na ₂ O, K ₂ O, Rb ₂ O and the content is determined, the total of these contents is 1.0 wt% or less of the entire ferrite sintered body. Is preferred. If these contents are too large, the saturation magnetization will be low.

  In addition to the above, for example, Ga, In, Li, Mg, Ti, Zr, Ge, Sn, V, Nb, Ta, Sb, As, W, and Mo may be contained as oxides. These contents are converted to oxides of stoichiometric composition, gallium oxide 5.0 wt% or less, indium oxide 3.0 wt% or less, lithium oxide 1.0 wt% or less, magnesium oxide 3.0 wt% or less, respectively. Titanium oxide 3.0 wt% or less, Zirconium oxide 3.0 wt% or less, Germanium oxide 3.0 wt% or less, Tin oxide 3.0 wt% or less, Vanadium oxide 3.0 wt% or less, Niobium oxide 3.0 wt% or less, Oxidation Tantalum is preferably 3.0 wt% or less, antimony oxide 3.0 wt% or less, arsenic oxide 3.0 wt% or less, tungsten oxide 3.0 wt% or less, and molybdenum oxide 3.0 wt% or less.

  The ferrite sintered magnet of the present invention has an average crystal grain size of preferably 1.5 μm or less, more preferably 1.0 μm or less, and still more preferably 0.2 to 1.0 μm. The crystal grain size can be measured with a scanning electron microscope.

Next, a preferred method for producing the sintered ferrite magnet of the present invention will be described.
The method for producing a sintered ferrite magnet according to the present invention includes a blending step, a calcination step, a coarse pulverization step, a fine pulverization step, a forming step in a magnetic field, and a firing step.

<Mixing process>
In the blending step, the raw material powder is weighed so as to have a predetermined ratio, and then mixed and pulverized by a wet attritor, a ball mill or the like for about 1 to 20 hours. As a starting material, a compound (for example, BaCO ₃ , SrCO ₃ , CaCO ₃ , La (OH) ₃ , Fe ₂ O ₃ ) containing one type of ferrite constituent elements (Ba, Sr, Ca, La, Fe, Co). And Co ₃ O ₄ ) or a compound containing two or more of these may be used. As the compound, an oxide or a compound that becomes an oxide by firing, for example, carbonate, hydroxide, nitrate, or the like is used. The average particle diameter of the starting material is not particularly limited, but it is usually preferable to set it to about 0.1 to 2.0 μm. It is not necessary to mix all starting materials in this step before calcination, and a part or all of each compound may be added after calcination.

<Calcination process>
The raw material composition obtained in the blending step is calcined. Calcination is usually performed in an oxidizing atmosphere such as air. The calcination temperature is preferably 1100 to 1450 ° C, more preferably 1150 to 1400 ° C, and further preferably 1200 to 1350 ° C. The stabilization time is preferably 1 second to 10 hours, more preferably 1 second to 3 hours. The material after calcination has 70% or more of M phase, and the primary particle diameter is preferably 10 μm or less, more preferably 2 μm or less.

<Crushing process>
The calcined body is generally in the form of granules, lumps, etc., and cannot be formed into a desired shape as it is, and is pulverized. In addition, a pulverization step is necessary to mix the raw material powder for adjusting to a desired final composition, additives, and the like. In this step, a part of the raw materials of the main component and subcomponent can be added, which is post-addition. The pulverization process is usually divided into a coarse pulverization process and a fine pulverization process. In addition, it can also be set as the ferrite magnet powder for bonded magnets by grind | pulverizing a calcined body to a predetermined particle size.

<Coarse grinding process>
As described above, since the calcined body is generally in the form of granules, lumps, etc., it is preferable to coarsely pulverize it. In the coarse pulverization step, a vibration mill or the like is used, and processing is performed until the average particle size becomes 0.5 to 5.0 μm. The powder obtained here will be referred to as coarsely pulverized powder.

<Fine grinding process>
The coarsely pulverized powder is pulverized by a wet attritor, ball mill, jet mill or the like, and the average particle size is 0.08 to 2.0 μm, preferably 0.1 to 1.0 μm, more preferably about 0.2 to 0.8 μm. Smash. The specific surface area (determined by the BET method) of the finely pulverized powder obtained is preferably about 7 to 12 m ² / g. Depending on the pulverization method, the pulverization time may be, for example, 30 minutes to 10 hours for a wet attritor and 10 to 40 hours for wet pulverization with a ball mill.

In carrying out fine grinding, it is preferable to add subcomponents. In particular, in the present invention, it is preferable to add SiO ₂ as the Si component and CaCO ₃ as the Ca component. This subcomponent is added for the purpose of improving the sinterability, controlling the magnetic properties, adjusting the crystal grain size of the sintered body, and the like.
The fine pulverization step can be divided into a first fine pulverization step and a second fine pulverization step, and a powder heat treatment step can be performed between the first fine pulverization step and the second fine pulverization step.

<Molding process in magnetic field>
The forming step in a magnetic field can be performed by either dry forming or wet forming, but is preferably performed by wet forming in order to increase the degree of magnetic orientation.
When wet molding is performed, the pulverization step is performed in a wet manner, and the obtained slurry is concentrated to a predetermined concentration to obtain a slurry for wet molding. Concentration may be performed by centrifugation or a filter press. In this case, it is preferable that the finely pulverized powder accounts for about 30 to 80 wt% in the slurry for wet molding. The dispersion medium is preferably water, and it is preferable that a surfactant such as gluconic acid and / or gluconate or sorbitol is added. Next, molding in a magnetic field is performed using a slurry for wet molding. The molding pressure may be about 0.1 to 0.5 ton / cm ² and the applied magnetic field may be about 5 to 15 kOe. The dispersion medium is not limited to water, and a non-aqueous solvent may be used. When a non-aqueous dispersion medium is used, an organic solvent such as toluene or xylene can be used. In this case, it is preferable to add a surfactant such as oleic acid.

<Baking process>
The obtained molded body is fired to obtain a sintered body. Firing is usually performed in an oxidizing atmosphere such as air. The baking temperature is 1050 to 1270 ° C., preferably 1080 to 1240 ° C., and the holding time is about 0.5 to 3 hours.

  When a molded body is obtained by wet molding, cracks may occur in the molded body if the molded body is heated rapidly without being sufficiently dried. In that case, it is preferable to sufficiently dry the molded body and suppress the generation of cracks by setting a slow temperature increase rate from room temperature to about 100 ° C., for example, about 10 ° C./hour. In addition, when a surfactant (dispersant) or the like is added, degreasing treatment is performed at a temperature rising rate of about 2.5 ° C./hour, for example, in a range of about 100 to 500 ° C. It is preferable to remove.

Now, in the nonreciprocal circuit device 1, the permanent magnet 7 is magnetized after the components are assembled (previously magnetized). Thereafter, the nonreciprocal circuit element 1 is measured for insertion loss and reverse loss as quality control.
An example is shown in FIG. FIG. 2 shows frequency characteristics of insertion loss and reverse loss obtained by changing the magnetizing magnetic field to 9.4 kOe, 10 kOe, and 10.8 kOe. By increasing the magnetization magnetic field, the peak of the insertion loss can be shifted to the high frequency side. However, even when magnetized with a strong magnetic field of 10.8 kOe or more, the peak of insertion loss cannot be shifted to a higher frequency side, specifically, 825 MHz or more.

  FIG. 3 shows frequency characteristics of insertion loss and reverse loss of the nonreciprocal circuit element 1 using the permanent magnet 7 according to the present invention. Also in this example, the peak of the insertion loss can be shifted to the high frequency side by increasing the magnetization magnetic field. In this example, the peak of the insertion loss can be shifted to 825 MHz or more by a magnetizing magnetic field of 8.6 kOe or more.

  As described above, since the permanent magnet 7 used in the measurement of FIG. 2 has a small margin, there is little amount that the peak of the insertion loss can be shifted to the high frequency side by the magnetization. On the other hand, according to the present invention, the amount of the insertion loss peak that can be shifted to the high frequency side due to the magnetization is large, so that even when the insertion loss characteristic deviates from the standard, it is easy to adjust the insertion loss characteristic to the standard. Become. This indicates that the product yield can be improved.

As starting materials, lanthanum hydroxide (La (OH) ₃ ), barium carbonate (BaCO ₃ ), calcium carbonate (CaCO ₃ ), strontium carbonate (SrCO ₃ ), iron oxide (Fe ₂ O ₃ ) and cobalt oxide (Co ₃ O) ₄ ) was prepared. The starting materials constituting these main components were weighed so that the main components after calcination excluding oxygen would have the following composition formulas (a) to (c) (molar ratio). Table 1 shows the weighed main components. In Table 1, the values of x, y, z, etc. of the above-described composition formula (1) are also shown.
Formula _{(a): La 0.6 Ca m} Sr 0.4-m Fe 11.0 Co 0.4
m = 0, 0.1, 0.2, 0.3, 0.375, 0.4
Formula _{(b): La 0.45 Ca m} Ba 0.1 Sr 0.45-m Fe 11.5 Co 0.3
m = 0,0.05,0.15,0.25,0.35
Formula _{(c): La 0.12 Ca m} Sr 0.88-m Fe 11.92 Co 0.08
m = 0, 0.044, 0.088, 0.176, 0.264, 0.352

The above blended raw materials were mixed and pulverized with a wet attritor to obtain a slurry-like raw material composition. After drying this slurry, calcination was carried out at 1350 ° C. (composition (a)), 1250 ° C. (composition (b)) or 1200 ° C. (composition (c)) for 3 hours in the air.
The obtained calcined body was coarsely pulverized by a rod vibration mill.
The next pulverization was performed in two stages using a ball mill. In the first pulverization step, water is added to the coarse powder and treated for 88 hours. After the first fine grinding step, the fine powder was heat-treated at 800 ° C. in the atmosphere.
Subsequently, water and sorbitol are added to the heat-treated powder, and then 0.62 wt% of SiO ₂ and 1.40 wt% of CaCO ₃ are added as subcomponents, followed by treatment for 25 hours in a wet ball mill. Went.

  The solid content concentration of the obtained finely pulverized slurry was adjusted, and a cylindrical molded body having a diameter of 30 mm and a thickness of 15 mm was obtained using a wet magnetic field molding machine in an applied magnetic field of 12 kOe. The molded body was sufficiently dried at room temperature in the atmosphere, and then fired at 1140 ° C. (composition formula (a), (b)) or 1180 ° C. (composition formula (c)) for 1 hour in the atmosphere.

  The composition (La, Ca, Ba, Sr, Fe, Co) of the obtained sintered body was measured by fluorescent X-ray quantitative analysis. Further, after processing the upper and lower surfaces of the obtained cylindrical sintered body, the residual magnetic flux density (Br) and the coercive force (HcJ) were measured using a B—H tracer having a maximum applied magnetic field of 25 kOe. Moreover, the ratio of the M-type ferrite phase was specified by X-ray diffraction under the above-described conditions for the phase structure of the obtained sintered body. The results are shown in Table 2. Moreover, the nonreciprocal circuit element 1 shown in FIG. 1 was produced using the obtained sintered magnet. In addition, the thickness of the permanent magnet 7 was 0.325 mm. About this nonreciprocal circuit element 1, after magnetizing with 8 kOe, it was evaluated whether the peak of insertion loss could be shifted by 825 MHz or more by magnetizing. When the peak of the insertion loss can be shifted to 825 MHz or more, “◯” is given. Furthermore, the sample No. is indicated on the (x, m) coordinates where x is the horizontal axis and m is the vertical axis. The graph which plotted 1-17 is shown in FIG.

In FIG. 4, the sample that can shift the peak of the insertion loss to the high frequency side of 825 MHz or higher is plotted with ◯, and the sample that cannot be plotted is plotted with ×. In FIG. The regions surrounding 3 to 5 and 8 to 10 are (0.37,0.10), (0.60,0.30), (0.54,0.45) and (x, m) coordinates. It is specified by a line segment connecting (0.37, 0.37). Therefore, in the present invention, x indicating the La amount in the composition formula (1) and m indicating the Ca amount are (0.37, 0.10), (0.60, 0.30) in the (x, m) coordinates. ), (0.54, 0.45) and (0.37, 0.37).
As described above, La-based hexagonal ferrite having a large amount of La in the hexagonal ferrite phase was obtained by containing a predetermined amount of Ca in addition to Ba and Sr at the A site. The ferrite permanent magnet can have a large margin so that the peak of insertion loss can be shifted to the high frequency side of 825 MHz or higher.

  5 and 6 show the relationship between the Ca content (m), the residual magnetic flux density (Br), and the coercive force (HcJ). 5 and 6, a high residual magnetic flux density (Br) and a coercive force (HcJ) can be obtained, and in order to increase the margin, m (Ca) is preferably 0.2 to 0.45. It is more preferable to set it as 0.25-0.45.

As starting materials, lanthanum hydroxide (La (OH) ₃ ), calcium carbonate (CaCO ₃ ), strontium carbonate (SrCO ₃ ), iron oxide (Fe ₂ O ₃ ), and cobalt oxide (Co ₃ O ₄ ) were prepared. The starting materials constituting these main components were weighed so that the main component after firing excluding oxygen would have the following formula (d) (molar ratio). Table 3 shows the weighed main components. In Table 3, the values of x, y, z, etc. of the above-described composition formula (1) are also shown.
Formula (d): La _0.6 Ca _0.3 Sr _0.1 Fe _11.4-yz Co _yz
x / yz: 2.00, 1.71, 1.50, 1.20

The above blended raw materials were mixed and pulverized with a wet attritor to obtain a slurry-like raw material composition. The slurry was dried and then calcined at 1350 ° C. for 3 hours in the air.
The obtained calcined body was coarsely pulverized by a rod vibration mill.
The next pulverization was performed in two stages using a ball mill. In the first pulverization step, water is added to the coarse powder and treated for 88 hours. After the first pulverization step, the fine powder was heat-treated at 800 ° C. in an air atmosphere.
Subsequently, water and sorbitol are added to the heat-treated powder, and then 0.62 wt% of SiO ₂ and 1.40 wt% of CaCO ₃ are added as subcomponents, followed by treatment for 25 hours in a wet ball mill. Went.

  The solid content concentration of the obtained finely pulverized slurry was adjusted, and a cylindrical molded body having a diameter of 30 mm and a thickness of 15 mm was obtained using a wet magnetic field molding machine in an applied magnetic field of 12 kOe. The molded body was sufficiently dried at room temperature in the atmosphere, and then fired by being held at 1140 ° C. for 1 hour in the atmosphere.

The composition (Sr, La, Ca, Fe, Co) of the obtained sintered body was measured by fluorescent X-ray quantitative analysis. Moreover, after processing the upper and lower surfaces of the obtained cylindrical sintered body, the residual magnetic flux density (Br) and the coercive force (HcJ) were measured using a B—H tracer having a maximum applied magnetic field of 25 kOe. The ratio of the M-type ferrite phase was specified by X-ray diffraction under the above-described conditions for the phase structure of the obtained sintered body. Further, in the same manner as in Example 1, it was evaluated whether or not the peak of the insertion loss can be shifted to the high frequency side of 825 MHz or higher for the nonreciprocal circuit element 1 using each sample.
The results are shown in Table 4. As shown in Table 4, when x / yz was 2.00, the peak of insertion loss could not be shifted to the high frequency side of 825 MHz or higher. Therefore, in the present invention, x / yz (La / Co) is set to 1.15 to 1.95.

  7 and 8 show the relationship between x / yz, residual magnetic flux density (Br), and coercive force (HcJ). From FIG. 7 and FIG. 8, in order to obtain a high residual magnetic flux density (Br) and coercive force (HcJ), and to increase the margin, x / yz is preferably set to 1.25 to 1.85. More preferably, it is set to .35 to 1.75.

As starting materials, lanthanum hydroxide (La (OH) ₃ ), calcium carbonate (CaCO ₃ ), strontium carbonate (SrCO ₃ ), iron oxide (Fe ₂ O ₃ ), and cobalt oxide (Co ₃ O ₄ ) were prepared. The starting materials constituting these main components were weighed so that the main component after firing excluding oxygen would have the following formula (e) (molar ratio). Table 5 shows the weighed main components. In Table 5, the values of x, y, z, etc. of the above-described composition formula (1) are also shown.
Formula (e): La _0.6 Ca _0.3 Sr _0.1 Fe _12z-0.4 Co _0.4
12z: 10.2 to 12.4

The above blended raw materials were mixed and pulverized with a wet attritor for 2 hours to obtain a slurry-like raw material composition. The slurry was dried and then calcined at 1350 ° C. for 3 hours in the air.
The obtained calcined body was coarsely pulverized by a rod vibration mill.
The next pulverization was performed in two stages using a ball mill. In the first pulverization step, water is added to the coarse powder and treated for 88 hours. After the first pulverization step, the fine powder was heat-treated at 800 ° C. in an air atmosphere.
Subsequently, water and sorbitol are added to the heat-treated powder, and then 0.62 wt% of SiO ₂ and 1.40 wt% of CaCO ₃ are added as subcomponents, followed by treatment for 25 hours in a wet ball mill. Went.

The composition (Sr, La, Ca, Fe, Co) of the obtained sintered body was measured by fluorescent X-ray quantitative analysis. Moreover, after processing the upper and lower surfaces of the obtained cylindrical sintered body, the residual magnetic flux density (Br) and the coercive force (HcJ) were measured using a B—H tracer having a maximum applied magnetic field of 25 kOe. The ratio of the M-type ferrite phase was specified by X-ray diffraction under the above-described conditions for the phase structure of the obtained sintered body. Further, in the same manner as in Example 1, it was evaluated whether or not the peak of the insertion loss can be shifted to the high frequency side of 825 MHz or higher for the nonreciprocal circuit element 1 using each sample.
The results are shown in Table 6. As shown in Table 6, it can be seen that when Fe + Co (12z) is 9.11, 11.07, the peak of insertion loss cannot be shifted to the high frequency side of 825 MHz or higher. Therefore, in the present invention, Fe + Co (12z) is set to 9.2-11.

  9 and 10 show the relationship between Fe + Co (12z), residual magnetic flux density (Br), and coercive force (HcJ). From FIG. 9 and FIG. 10, high residual magnetic flux density (Br) and coercive force (HcJ) are obtained, and in order to increase the margin, Fe + Co (12z) is preferably 9.2 to 10.9, 9.4 to 10.8 and more preferably 9.7 to 10.5 are more preferable.

As starting materials, lanthanum hydroxide (La (OH) ₃ ), calcium carbonate (CaCO ₃ ), barium carbonate (BaCO ₃ ), iron oxide (Fe ₂ O ₃ ), and cobalt oxide (Co ₃ O ₄ ) were prepared. The starting materials constituting these main components were weighed so that the main component after firing excluding oxygen would have the following formula (f) (molar ratio). Table 7 shows the weighed main components. In Table 7, the values of x, y, z, etc. of the above-described composition formula (1) are also shown.
Formula (f): La _0.6 Ca _0.3 Ba _0.1 Fe _12z-0.4 Co _0.4
12z: 11.4-11.8

The above blended raw materials were mixed and pulverized with a wet attritor for 2 hours to obtain a slurry-like raw material composition. After the slurry was dried, calcination was performed in the air at 1300 ° C. for 3 hours.
The obtained calcined body was coarsely pulverized by a rod vibration mill.
The next pulverization was performed in two stages using a ball mill. In the first pulverization step, water is added to the coarse powder and treated for 88 hours. After the first pulverization step, the fine powder was heat-treated at 800 ° C. in an air atmosphere.
Subsequently, water and sorbitol are added to the heat-treated powder, and then 0.62 wt% of SiO ₂ and 1.40 wt% of CaCO ₃ are added as subcomponents, followed by treatment for 25 hours in a wet ball mill. Went.

The composition (La, Ca, Ba, Fe, Co) of the obtained sintered body was measured by fluorescent X-ray quantitative analysis. Moreover, after processing the upper and lower surfaces of the obtained cylindrical sintered body, the residual magnetic flux density (Br) and the coercive force (HcJ) were measured using a B—H tracer having a maximum applied magnetic field of 25 kOe. Moreover, the ratio of the M-type ferrite phase was specified by X-ray diffraction under the above-described conditions for the phase structure of the obtained sintered body. Further, in the same manner as in Example 1, it was evaluated whether or not the peak of the insertion loss can be shifted to the high frequency side of 825 MHz or higher for the nonreciprocal circuit element 1 using each sample.
Table 8 shows the above results. As shown in Table 8, even if the element α is Ba, the peak of insertion loss can be shifted to the high frequency side of 825 MHz or higher.

It is a disassembled perspective view which shows the structure of the nonreciprocal circuit device by this Embodiment. It is a graph which shows an example of the frequency characteristic of the insertion loss and reverse loss which were obtained by changing the magnetization magnetic field. It is a graph which shows the other example of the frequency characteristic of the insertion loss and reverse loss which were obtained by changing the magnetization magnetic field. In Example 1, the sample No. is displayed on the (x, m) coordinates. It is the graph which plotted 1-17. It is a graph which shows the relationship between Ca amount (m) and residual magnetic flux density (Br) in Example 1. It is a graph which shows the relationship between Ca amount (m) and coercive force (HcJ) in Example 1. It is a graph which shows the relationship between La / Co (x / yz) and residual magnetic flux density (Br) in Example 2. It is a graph which shows the relationship between La / Co (x / yz) and coercive force (HcJ) in Example 2. It is a graph which shows the relationship between the amount of Fe + Co (12z) and residual magnetic flux density (Br) in Example 3. It is a graph which shows the relationship between the amount of Fe + Co (12z) and coercive force (HcJ) in Example 3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Non-reciprocal circuit element (isolator), 2 ... Magnetic rotor, 3 ... Center electrode, 4 ... Soft-magnetic base | substrate, 7 ... Permanent magnet, 9 ... Case, 91 ... Case main body, 92 ... Cover

Claims (3)

In the non-reciprocal circuit element provided with a permanent magnet that applies a DC magnetic field to the soft magnetic substrate while abutting a soft magnetic substrate on the intersecting portions of the plurality of central conductors arranged in an electrically insulated state,
The permanent magnet is
The ferrite phase having a hexagonal crystal structure forms the main phase, and the composition ratio of the metal elements constituting the main phase is
Composition formula (1): When represented by _{La x Ca m α 1-x} -m (Fe 12-y Co y) z,
α is one or two of Ba and Sr,
x and m are (0.37,0.10), (0.60,0.30), (0.54,0.45) and (0) in the (x, m) coordinates shown in FIG. .37, 0.37) in the region enclosed by
1.15 ≦ x / yz ≦ 1.95,
A non-reciprocal circuit device, which is a sintered ferrite magnet having a composition represented by 9.2 ≦ 12z ≦ 11. 2. The nonreciprocal circuit device according to claim 1, wherein m is 0.2 to 0.45.
  3. The nonreciprocal circuit device according to claim 1, wherein 1.25 ≦ x / yz ≦ 1.85.

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