TW201931388A - Magnetic material and electronic component - Google Patents

Abstract

A magnetic material has: multiple soft magnetic alloy grains that contain Fe, element L (where element L is Si, Zr, or Ti), and element M (where element M is not Si, Zr, or Ti, and oxidizes more easily than Fe); a first oxide film that contains element L and covers each of the multiple soft magnetic alloy grains; a second oxide film that contains element M and covers the first oxide film; a third oxide film that contains element L and covers the second oxide film; a fourth oxide film that contains Fe and covers the third oxide film; and bonds that are constituted by parts of the fourth oxide film and that bond the multiple soft magnetic alloy grains together.

Description

Magnetic materials and electronic parts

The present invention relates to a magnetic material mainly used as a magnetic core in a coil, an inductor or the like and an electronic component using the same.

An electronic component such as an inductor, a yoke, or a transformer has a magnetic body as a magnetic core and a coil formed inside or on the surface of the magnetic body. As the material of the magnetic material, for example, a ferrite material such as NiCuZn-based ferrite is usually used.
In recent years, a large current is required for such an electronic component, and in order to satisfy this requirement, it has been studied to switch a material of a magnetic material from a prior ferrite to a metal-based material. As a metal-based material, a FeSiCr alloy, a FeSiAl alloy, or the like is known. For example, Patent Document 1 discloses that an alloy phase of a FeSiCr-based soft magnetic alloy powder is bonded to each other via an oxide phase containing Fe, Si, and Cr. core.
On the other hand, the metal-based magnetic material has a higher saturation magnetic flux density than the ferrite, but the volume resistivity of the material itself is lower than that of the prior ferrite, and thus the electrical insulating property is required to be further improved. For example, Patent Document 2 discloses a soft magnetic powder magnetic core in which a glass portion is interposed between particles of soft magnetic metal particles containing Fe as a main component. The glass portion is formed by softening the low-melting glass material by heat under pressure. The low-melting glass material has a low melting point, and by diffusion reaction between the soft magnetic metal particles, it is possible to fill a void which cannot be completely filled with the oxide portion covering the surface of the soft magnetic metal particle.
[Previous Technical Literature]
[Patent Literature]
[Patent Document 1] Japanese Patent Laid-Open No. 2015-126047
[Patent Document 2] Japanese Patent Laid-Open No. 2015-144238

[The problem that the invention wants to solve]
However, it is difficult to fill the gap between the alloy particles using glass, and there is a problem of lack of insulation stability. Further, even if the gap between the alloy particles can be filled with glass, the oxidation reaction of the alloy particles becomes unstable, and the insulating properties are lowered.
In view of the above circumstances, an object of the present invention is to provide a magnetic material and an electronic component which can improve insulation properties.
[Technical means to solve the problem]
In order to achieve the above object, a magnetic material according to one aspect of the present invention includes a plurality of magnetic alloy particles, a first oxide film, a second oxide film, a third oxide film, a fourth oxide film, and a bonding portion.
The plurality of magnetic alloy particles include Fe, an element L (wherein the element L is any one of Si, Zr, and Ti) and an element M (wherein the element M is other than Si, Zr, Ti, and is more easily oxidized than Fe) element).
The first oxide film contains the element L and covers the plurality of soft magnetic alloy particles.
The second oxide film contains the element M and covers the first oxide film.
The third oxide film is amorphous, and contains the element L and covers the second oxide film.
The fourth oxide film contains Fe and covers the third oxide film.
The bonding portion is composed of one of the fourth oxide films, and the plurality of soft magnetic alloy particles are bonded to each other.
In the magnetic material, the surface of the soft magnetic alloy particles is covered by the first to fourth oxide films, so that it is possible to effectively improve the bonding between the soft magnetic alloy particles bonded through the joint portion formed of one of the fourth oxide films. Insulation properties.
Typically, the element M is Cr and the element L is Si.
The third oxide film may have a thickness equal to or greater than the thickness of the first oxide film.
The thickness of the third oxide film is not particularly limited, and is, for example, 1 nm or more and 20 nm or less.
A magnetic material according to another aspect of the present invention includes a plurality of magnetic alloy particles, a first oxide film, a second oxide film, a third oxide film, and a fourth oxide film.
The plurality of magnetic alloy particles include Fe, an element L (wherein the element L is any one of Si, Zr, and Ti) and an element M (wherein the element M is other than Si, Zr, Ti, and is more easily oxidized than Fe) element).
The first oxide film contains the element L and covers the plurality of soft magnetic alloy particles.
The second oxide film contains the element M and covers the first oxide film.
The third oxide film is amorphous, and contains the element L and covers the second oxide film.
The fourth oxide film contains Fe and covers the third oxide film.
An electronic component according to an aspect of the present invention includes a magnetic core including the magnetic material.
[Effects of the Invention]
According to the present invention, an improvement in insulation characteristics can be achieved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Fig. 1 is a perspective view showing a whole of a coil component (layered inductor) of an electronic component according to an embodiment of the present invention. Figure 2 is a cross-sectional view taken along line A-A of Figure 1.
[Composition of coil parts]
The coil component 10 of the present embodiment has a component body 11 and a pair of external electrodes 14, 15 as shown in FIG. The component body 11 is formed in a rectangular parallelepiped shape having a width W in the X-axis direction, a length L in the Y-axis direction, and a height H in the Z-axis direction. The pair of external electrodes 14 and 15 are provided on the opposite end faces of the component body 11 in the longitudinal direction (Y-axis direction).
The size of each part of the part body 11 is not particularly limited. In the present embodiment, the length L is 1.6 to 2 mm, the width W is 0.8 to 1.2 mm, and the height H is 0.4 to 0.6 mm.
As shown in FIG. 2, the component main body 11 has a magnetic body portion 12 having a rectangular parallelepiped shape and a spiral coil portion 13 (internal conductor) covered by the magnetic body portion 12.
3 is an exploded perspective view of the part body 11. Figure 4 is a cross-sectional view taken along line B-B of Figure 1.
As shown in FIG. 3, the magnetic body portion 12 has a structure in which a plurality of magnetic layers MLU, ML1 to ML7, and MLD are laminated in the height direction (Z-axis direction). The magnetic layers MLU and MLD constitute a coating layer (third magnetic layer) above and below the magnetic body portion 12. The magnetic layers ML1 to ML7 constitute a conductor layer including the coil portion 13, and as shown in FIG. 4, each has a first magnetic layer 121, a second magnetic layer 122, and conductor patterns C11 to C17.
The first magnetic layer 121 is formed as an inter-conductor layer interposed between the conductor patterns C11 to C17 that are adjacent to each other. Soft magnetic alloy particles are used for the first magnetic layer 121. As the soft magnetic alloy particles, in the present embodiment, for example, FeSiCr-based alloy magnetic particles are used. The composition of the soft magnetic alloy particles is typically 1 to 5 wt% for Cr and 2 to 10 wt% for Si, and the remainder of the peripheral portion is Fe, which is 100 wt% as a whole.
The average particle diameter (median diameter) in the case of the volume-based particle diameter of the soft magnetic alloy particles can be based on the target magnetic properties (relative magnetic permeability, inductance, saturation magnetization, etc.), and the first magnetic layer 121. The thickness is set as appropriate. As an example, when the thickness of the first magnetic layer 121 is 4 μm or more and 20 μm or less, the average particle diameter of the soft magnetic alloy particles constituting the first magnetic layer 121 is set to the thickness direction in the thickness dimension (Z). The size of the four or more alloy particles is arranged in the axial direction, and is, for example, 1 μm or more and 5 μm or less.
As the soft magnetic alloy particles, in addition to FeSiCr, FeZrCr, FeSiAl, FeSiTi, FeZrAl, FeZrTi, or the like can be used. In other words, the soft magnetic alloy particles are more likely to contain Fe as a main component, and an element containing at least one of Si, Zr, and Ti (hereinafter also referred to as element L) and Fe other than Si, Zr, and Ti are easier. One or more elements (hereinafter, also referred to as element M) such as Cr or Al which are oxidized may be used. By using such a magnetic material, the following oxide film is stably formed on the surface of the soft magnetic alloy particles, and in particular, even when heat treatment is performed at a low temperature, the insulating property can be improved.
Further, in the FeSiCr-based alloy, the remainder other than Si and Cr is preferably Fe in addition to unavoidable impurities. Examples of the metal which may be contained in addition to Fe, Si, and Cr include Al, Mg (magnesium), Ca (calcium), Ti, Mn (manganese), Co (cobalt), Ni (nickel), and Cu (copper). Examples of the non-metal include P (phosphorus), S (sulfur), and C (carbon).
The conductor patterns C11 to C17 are disposed on the first magnetic layer 121. As shown in FIG. 2, the conductor patterns C11 to C17 constitute one portion of a coil wound around the Z-axis, and are electrically connected to each other in the Z-axis direction via the through holes V1 to V6, thereby forming the coil portion 13. The conductor pattern C11 of the magnetic layer ML1 has a lead end 13e1 electrically connected to an external electrode 14, and the conductor pattern C17 of the magnetic layer ML7 has a lead end 13e2 electrically connected to the other external electrode 15.
The second magnetic layer 122 is composed of soft magnetic alloy particles (in this example, FeCrSi alloy particles) of the same type as the first magnetic layer 121. The second magnetic layer 122 is opposed to the first magnetic layer 121 in the Z-axis direction, and is disposed around the conductor patterns C11 to C17 on the first magnetic layer 121 (outer peripheral region and inner peripheral region). The thickness of the second magnetic layer 122 in each of the magnetic layers ML1 to ML7 in the Z-axis direction is typically the same as the thickness of the conductor patterns C11 to C17, but the thickness may be different.
In the present embodiment, the second magnetic layer 122 is made of a magnetic material having a higher electrical resistance than the first magnetic layer 121. Thereby, the desired electrical insulating properties between the conductor patterns C11 to C17 and the external electrodes 14, 15 can be stably ensured. The difference between the magnetic material constituting the first magnetic layer 121 and the magnetic material constituting the second magnetic layer 122 will be described below.
The third magnetic layer 123 is composed of soft magnetic alloy particles (in this example, FeCrSi alloy particles) of the same type as the first magnetic layer 121. The third magnetic layer 123 corresponds to the upper magnetic layer MLU and the lower magnetic layer MLD, and the first magnetic layer 121, the second magnetic layer 122, and the conductor patterns C11 to C17 (coil portion 13) via the magnetic layers ML1 to ML7. It is arranged in the opposite direction in the Z-axis direction. Each of the magnetic layers MLU and MLD is composed of a laminate of a plurality of third magnetic layers 123, and the number of the layers is not particularly limited. Further, the first magnetic layer 121 of the magnetic layer ML7 may be composed of the third magnetic layer 123 located at the uppermost layer of the magnetic layer MLD. Further, the lowermost layer of the magnetic layer MLU may be composed of the first magnetic layer 121.
Then, the coil portion 13 is made of a conductive material, and has a lead end portion 13e1 electrically connected to the external electrode 14, and a lead end portion 13e2 electrically connected to the external electrode 15. The coil portion 13 is made of a calcined body of a conductive paste, and in the present embodiment, is composed of a calcined body of a silver (Ag) paste.
The coil portion 13 is spirally wound around the inside of the magnetic body portion 12 in the height direction (Z-axis direction). As shown in FIG. 3, the coil portion 13 has seven conductor patterns C11 to C17 which are formed in a specific shape on the magnetic layers ML1 to ML7, and a total of six through holes in which the conductor patterns C11 to C17 are connected in the Z-axis direction. V1 to V6 are configured by integrating these spirals. Further, the conductor patterns C12 to C16 correspond to the surrounding portion of the coil portion 13, and the conductor patterns C11 and C17 correspond to the lead portions of the coil portion 13. The number of turns of the coil portion 13 shown in the figure is about 5.5, but it is of course not limited thereto.
As shown in FIG. 3, when viewed from the Z-axis direction, the coil portion 13 is formed in an elliptical shape having the long side direction of the magnetic body portion 12 as a long axis. Thereby, the path of the current flowing through the coil portion 13 can be minimized, so that the resistance of the DC resistance can be reduced. Here, the elliptical shape is typically an ellipse or an ellipse (a shape in which two semicircles are connected by a straight line), a rounded rectangular shape, or the like. Further, the coil portion 13 may be a substantially rectangular shape when viewed from the Z-axis direction.
[Details of the magnetic body]
Next, the details of the magnetic body portion 12 will be described.
On the surface of the soft magnetic alloy particles (FeCrSi alloy particles) constituting the first to third magnetic layers 121 to 123, an oxide of the FeCrSi alloy particles is present as an insulating film. The FeCrSi alloy particles in the magnetic layers 121 to 123 are bonded to each other via the oxide, and the FeCrSi alloy particles in the vicinity of the coil portion 13 are in close contact with the coil portion 13 via the oxide. The above oxides typically contain Fe belonging to a magnetic body.₃ O₄ And non-magnetic Fe₂ O₃ ,Cr₂ O₃ SiO₂ At least one of them.
(first magnetic layer)
5 is a schematic cross-sectional view of the first oxide F1 formed on the surface of the soft magnetic alloy particles P1 constituting the first magnetic layer 121, and FIG. 6 is a schematic view showing a laminated structure of the first oxide F1.
The entire first magnetic layer 121 is composed of an aggregate in which a plurality of independent soft magnetic alloy particles P1 are bonded to each other, or a compact including a plurality of soft magnetic alloy particles P1. In FIG. 5, the vicinity of the interface of the three soft magnetic alloy particles P1 is enlarged and described.
At least a part of the soft magnetic alloy particles P1 is formed with at least a part of the periphery thereof, preferably almost all of the first oxide F1, and the insulating property of the first magnetic layer 121 is ensured by the first oxide F1. The adjacent soft magnetic alloy particles P1 are mainly bonded to each other via the first oxide F1 located around each of the soft magnetic alloy particles P1, and as a result, a magnetic body having a fixed shape is formed. Adjacent soft magnetic alloy particles P1 may also be bonded to each other locally in the metal portion. Further, it is preferable that substantially no matrix containing an organic resin is contained in any of the cases of bonding via the first oxide F1 and the case of bonding the metal portions to each other.
Each of the soft magnetic alloy particles P1 is at least an alloy containing at least iron (Fe) and two elements (elements L and M) which are more easily oxidized than iron. The element L is different from the element M and is a metal element or Si. In the case where the elements L and M are metal elements, typically, Cr (chromium), Al (aluminum), Zr (zirconium), Ti (titanium), or the like is preferable, and Cr or Al is preferable, and further preferably Contains Si or Zr.
In the entire magnetic material (first magnetic layer 121), the Fe content is preferably 92.5 to 96% by weight. In the case of the above range, a higher volume resistivity can be ensured. The content of the element L is preferably from 2.5 to 6% by weight in the entire magnetic body. The content of the element M is preferably from 1.5 to 4.5% by weight in the entire magnetic body. Examples of the element which may be contained in addition to Fe and the elements L and M include Mn (manganese), Co (cobalt), Ni (nickel), Cu (copper), P (phosphorus), S (sulfur), and C (carbon). )Wait. The composition of the entire magnetic body can be calculated, for example, by performing plasma luminescence analysis on the cross section of the magnetic body.
The first oxide F1 is typically composed of an oxide film having a three-layer structure, that is, the first oxide film F11, the second oxide film F12, and the first layer (ie, the inner side) from the magnetic alloy particle P1. 3 oxide film F13.
The first oxide film F11 contains more oxides of the element L than the element M. On the other hand, the second oxide film F12 contains more oxides of the element M than the element L. In the present embodiment, the element L is Si, and the first oxide film F11 is SiO.₂ . On the other hand, the element M is Cr, and the second oxide film F12 is Cr.₂ O₃ . The third oxide film F13 contains more Fe oxide than the elements L and M (Fe)_x O_y ). The oxide of Fe is typically a Fe belonging to a magnetic body.₃ O₄ Or a non-magnetic Fe₂ O₃ .
The element L included in the first oxide film F11 and the element M included in the second oxide film F12 are both obtained by diffusion and precipitation of Si and Cr which are constituent components of the soft magnetic alloy particles P1. Similarly, the Fe contained in the third oxide film F13 is equivalent to the diffusion and precipitation of Fe which is a constituent component of the soft magnetic alloy particles P1.
As shown in FIG. 5, the first magnetic layer 121 has a joint portion V1 that bonds the soft magnetic alloy particles P1 to each other. The joint portion V1 is composed of one portion of the third oxide film F13, and a plurality of soft magnetic alloy particles P1 are bonded to each other. The increase in mechanical strength and insulation can be achieved by the presence of the joint portion V1.
It is preferable that the first magnetic layer 121 is bonded to the entire soft magnetic alloy particles P1 via the joint portion V1. However, the soft magnetic alloy particles P1 may be partially bonded to each other without passing through the first oxide F1. region. Further, the first magnetic layer 121 may partially include the joint portion V1 and the joint portion other than the joint portion V1 (the joint portion of the soft magnetic alloy particles P1), but only the physical contact or the close contact form. . Further, the first magnetic layer 121 may partially have a void.
The first oxide F1 may be formed at the stage of forming the raw material particles before the magnetic material (the first magnetic layer 121), or may be absent or rarely present in the stage of the raw material particles, and may be generated during the forming process. 1 oxide F1. When the soft magnetic alloy particles P1 before the forming are subjected to heat treatment to obtain a magnetic material, it is preferable that the surface of the soft magnetic alloy particles P1 is partially oxidized to generate the first oxide F1, and the first oxide F1 is generated to make the plural The soft magnetic alloy particles P1 are combined.
In particular, since the first oxide film F11 is formed so as to cover the entire surface of the soft magnetic alloy particles P1, it is preferable that the content of the element L is higher than the element M in the entire magnetic body. Since the first oxide film F11 is present, stable insulation properties can be obtained. In addition, by setting the content of the element M to 1.5 to 4.5% by weight, it is estimated that excessive oxidation can be suppressed and the thickness of the first and second oxide films can be reduced.
(2nd magnetic layer)
On the other hand, FIG. 7 is a schematic cross-sectional view of the second oxide F2 formed on the surface of the soft magnetic alloy particles P2 constituting the second magnetic layer 122, and FIG. 8 is a schematic view showing a laminated structure of the second oxide F2.
Similarly, the second magnetic layer 122 is composed of an aggregate in which a plurality of soft magnetic alloy particles P2 are bonded to each other or a green compact including a plurality of soft magnetic alloy particles P2. In Fig. 7, the vicinity of the interface between the three soft magnetic alloy particles P2 is enlarged and described.
At least a part of the soft magnetic alloy particles P2 are preferably formed with the second oxide F2 in almost at least a part of the periphery thereof, and the second oxide layer 122 can ensure the insulation of the second magnetic layer 122. The adjacent soft magnetic alloy particles P2 are mainly bonded to each other via the second oxide F2 located around each of the soft magnetic alloy particles P2, and as a result, a magnetic body having a fixed shape is formed. The adjacent soft magnetic alloy particles P2 may be partially bonded to each other at the metal portion. However, in order to make the insulation more reliable, it is preferable to form the magnetic body by bonding by the second oxide F2. Further, it is preferable that substantially no matrix containing an organic resin is contained in any of the cases of bonding via the second oxide F2 and the case of bonding the metal portions to each other.
Each of the soft magnetic alloy particles P2 is at least an alloy containing at least iron (Fe) and two elements (elements L and M) which are more easily oxidized than iron. The element L is different from the element M and is a metal element or Si. In the case where the elements L and M are metal elements, typically, Cr (chromium), Al (aluminum), Zr (zirconium), Ti (titanium), or the like is preferable, and Cr or Al is preferable, and further preferably Contains Si or Zr.
In the entire magnetic material (second magnetic layer 122), the Fe content is preferably 92.5 to 96% by weight. In the case of the above range, a higher volume resistivity can be ensured. The content of the element L is preferably from 2.5 to 6% by weight in the entire magnetic body. The content of the element M is preferably from 1.5 to 4.5% by weight in the entire magnetic body. The composition of the entire magnetic body can be calculated, for example, by performing plasma luminescence analysis on the cross section of the magnetic body.
Examples of the element which may be contained in addition to Fe and the elements L and M include Mn (manganese), Co (cobalt), Ni (nickel), Cu (copper), P (phosphorus), S (sulfur), and C (carbon). )Wait.
The second oxide F2 is typically composed of an oxide film having a four-layer structure, that is, a first oxide film F21 covering the soft magnetic alloy particles P2, a second oxide film F22 covering the first oxide film F21, and a second oxide layer. The third oxide film F23 of the film F22 and the fourth oxide film F24 covering the third oxide film F23.
The first oxide film F21 and the third oxide film F23 contain an oxide of the element L, and typically contain more oxides of the element L than the element M. On the other hand, the second oxide film F22 contains an oxide of the element M, and typically contains more oxides of the element M than the element L. In the present embodiment, the element L is Si, and the first and third oxide films F21 and F23 are SiO.₂ . On the other hand, the element M is Cr, and the second oxide film F22 is Cr.₂ O₃ . The fourth oxide film F24 contains more Fe oxide than the element L (Fe_x O_y ). The oxide of Fe is typically a Fe belonging to a magnetic body.₃ O₄ Or a non-magnetic Fe₂ O₃ .
The element L included in the first oxide film F21 and the element M included in the second oxide film F22 correspond to diffusion and precipitation of Si and Cr which are constituent components of the soft magnetic alloy particles P2. Similarly, the Fe contained in the fourth oxide film F24 is equivalent to the diffusion and precipitation of Fe which is a constituent component of the soft magnetic alloy particles P2. On the other hand, the element L (Si) constituting the third oxide film F23 is SiO which is previously formed on the surface of the soft magnetic alloy particle P2 as described below.₂ The film is composed.
The presence of the second oxide F2 can be confirmed by a composition map of a scanning electron microscope (SEM) having a magnification of about 5000 times. The presence of the first to fourth oxide films F21 to F24 constituting the second oxide F2 can be confirmed by a composition map of a transmission electron microscope (TEM) having a magnification of about 20,000. The thickness of the first to fourth oxide films F21 to F24 can be confirmed by an energy dispersive X-ray analyzer (EDS) having a magnification of about 800,000 times.
By the presence of the second oxide F2, the insulation of the entire magnetic body can be ensured. In particular, since the second oxide F2 further includes an oxide film (third oxide film F23) than the first oxide F1, higher insulating properties than the first oxide F1 can be obtained.
As shown in FIG. 7, the second magnetic layer 122 has a joint portion V2 that bonds the soft magnetic alloy particles P2 to each other. The joint portion V2 is composed of a portion of the fourth oxide film F24, and a plurality of soft magnetic alloy particles P2 are bonded to each other. The presence of the bonding portion V2 can be visually recognized, for example, from an SEM observation image that is enlarged to about 5000 times. The increase in mechanical strength and insulation can be achieved by the presence of the joint portion V2.
It is preferable that the second magnetic layer 122 is bonded to the entire soft magnetic alloy particles P2 via the joint portion V2. However, the soft magnetic alloy particles P2 may be partially bonded to each other without passing through the second oxide F2. . Further, the second magnetic layer 122 may partially include the joint portion V2 and the joint portion other than the joint portion V2 (the joint portion of the soft magnetic alloy particles P1), but only the physical contact or the close contact form. . Further, the second magnetic layer 122 may partially have a void.
The second oxide F2 may be formed at the stage of forming the raw material particles before the magnetic material (the second magnetic layer 122), or may be absent or rarely present in the stage of the raw material particles, and may be generated during the forming process. Second oxide F2.
In the present embodiment, the pretreatment of forming the third oxide film F23 on the surface of the soft magnetic alloy particles P2 is performed at the stage of forming the raw material particles before the magnetic material (the second magnetic layer 122). When the magnetic material (second magnetic layer 122) is obtained by heat-treating the soft magnetic alloy particles P2 before molding, the surface of the soft magnetic alloy particles P2 is partially oxidized to generate the first oxide film F21 and the second oxide film F22. The fourth oxide film F24 and the bonding portion V2.
The method of pretreating the coating material constituting the third oxide film F23 on the surface of the raw material particles is not particularly limited, and in the present embodiment, a coating process using a sol-gel method is used. Typically, it will contain TEOS (tetraethoxy decane, Si (OC)₂ H₅ )₄ After mixing and stirring the treatment liquid of ethanol and water to a mixed liquid containing soft magnetic alloy particles P2, ethanol, and ammonia water, the soft magnetic alloy particles P2 are filtered and separated, and dried, thereby being formed on the surface. Contains SiO₂ Soft magnetic alloy particles P2 of a coating material of a film.
Here, if the treatment liquid is mixed into the mixed liquid at a time, uniform nucleation is dominant, and SiO is dominant.₂ The particles are nucleated in the solution, and the crystal grains grow to form an aggregate, and the aggregate adheres to the surface of the soft magnetic alloy particles P2, whereby the coating material cannot be stably formed. Therefore, in the present embodiment, the treatment liquid is mixed and added to the mixed liquid in a plurality of times, and mixed to suppress SiO.₂ The uniform nucleation of the particles makes the uneven nucleation on the surface of the soft magnetic alloy particles P2 dominant, whereby the coating material can be stably formed on the surface of the soft magnetic alloy particles P2.
The thickness of the third oxide film F23 (coating material) can be adjusted according to the amount of TEOS (Tetraethyl orthosilicate) contained in the treatment liquid, and the larger the amount of TEOS, the thicker the film can be obtained. The thickness of the third oxide film F23 is not particularly limited, but is preferably 1 nm or more and 20 nm or less. When the thickness is less than 1 nm, the coverage of the third oxide film F23 is deteriorated, and it is difficult to improve the insulation characteristics. In addition, when the thickness exceeds 20 nm, the filling rate of the soft magnetic alloy particles P2 is lowered, and the magnetic properties tend to be lowered.
Further, the thickness of the third oxide film F23 may be equal to or greater than the thickness of the first oxide film F21 or may be smaller than the thickness of the first oxide film F21. By making the thickness of the third oxide film F23 equal to or higher than the thickness of the first oxide film F21, the insulating property can be effectively improved as compared with the case where the third oxide film F23 is not present. On the other hand, by making the thickness of the third oxide film F23 smaller than the thickness of the first oxide film F21, it is possible to suppress a decrease in magnetic characteristics (relative magnetic permeability, etc.) due to the presence of the third oxide film F23.
In particular, since the first oxide film F21 is formed so as to cover the entire surface of the soft magnetic alloy particles P2, it is preferable that the content of the element L is higher than the element M in the entire magnetic body. Since the first oxide film F21 is present, stable insulation properties can be obtained. In addition, by setting the content of the element M to 1.5 to 4.5% by weight, it is possible to suppress excessive oxidation and to reduce the thickness of the first and second oxide films F21 and F22. Further, the first, second, third, and fourth oxide films F21 to F24 obtained herein are amorphous, amorphous, amorphous, and crystalline, respectively. The first, second, third, and fourth oxide films are formed by alternately forming films having different properties to form an oxide film having both insulating properties and oxidation inhibition, and are obtained by not having a desired thickness or more. A magnetic body that increases the relative magnetic permeability and has both insulation properties.
(3rd magnetic layer)
The magnetic material constituting the third magnetic layer 123 may be configured in the same manner as the first magnetic layer 121 or may be configured in the same manner as the second magnetic layer 122. Typically, the third magnetic layer 123 is made of a magnetic material having magnetic properties equal to or higher than those of the first magnetic layer 121.
[Manufacturing method of coil parts]
Next, a method of manufacturing the coil component 10 will be described. 9A to 9C are schematic cross-sectional views showing a main part of a method of manufacturing the magnetic layers ML1 to ML7 of the coil component 10.
The manufacturing method of the magnetic layers ML1 to ML7 includes a manufacturing step of the first magnetic layer 121, a forming step of the conductor pattern C10, and a manufacturing step of the second magnetic layer 122.
(production of the first magnetic layer)
When the first magnetic layer 121 is produced, a magnetic paste (slurry) prepared in advance is applied to a base film made of plastic (not shown) by using a coater (not shown) such as a doctor blade or a die coater. ) the surface. Then, the base film is dried at a temperature of about 80 ° C for about 5 minutes using a dryer (not shown) such as a hot air dryer to produce first to seventh magnetic sheets 121S corresponding to the magnetic layers ML1 to ML7 ( Refer to Figure 9A). The magnetic sheets 121S are each formed to have a size of a plurality of first magnetic layers 121.
The composition of the magnetic paste used herein is such that the FeCrSi alloy particle group (soft magnetic alloy particles P1) is 75 to 85 wt%, and the butyl carbitol (solvent) is 13 to 21.7 wt%, and polyvinyl butyral (bonding) The agent is 2 to 3.3 wt%, and is adjusted according to the average particle diameter (median diameter) of the FeCrSi particle group. For example, when the average particle diameter (median diameter) of the FeCrSi alloy particle group is 3 μm or more, it is set to 85 wt%, 13 wt%, 2 wt%, and is less than 1.5 μm and less than 3 μm. In the case of the case, it is set to 80 wt%, 17.3 wt%, and 2.7 wt%, respectively, and when it is less than 1.5 μm, it is set to 75 wt%, 21.7 wt%, and 3.3 wt%, respectively. The average particle diameter of the FeCrSi alloy particle group is selected according to the thickness of the first magnetic layer 121 and the like. The FeCrSi alloy particle group is produced, for example, by an atomization method.
The first magnetic layer 121 is formed by arranging four or more alloy magnetic particles (FeCrSi alloy particles) in the thickness direction, and has a thickness of, for example, 5 μm or more and 25 μm or less. In the present embodiment, the average particle diameter of the alloy magnetic particles is preferably from 1 to 4 μm in terms of d50 (median diameter) on a volume basis. The d50 of the alloy magnetic particles is measured using a particle size and particle size distribution measuring apparatus (for example, Microtrac manufactured by Nikkiso Co., Ltd.) by a laser diffraction scattering method.
Then, the first to sixth magnetic sheets 121S corresponding to the magnetic layers ML1 to ML6 are formed in a specific arrangement and through holes V1 to V6 by using a punching machine (not shown) such as a punching machine or a laser processing machine. (Refer to Fig. 3) Corresponding through holes (not shown). In the arrangement of the through holes, the first to seventh magnetic sheets 121S are stacked so as to form internal conductors in the through holes filled with the conductors and the conductor patterns C11 to C17.
(formation of conductor pattern)
Then, as shown in FIG. 9B, conductor patterns C11 to C17 are formed on the first to seventh magnetic sheets 121S.
The conductor pattern C11 is printed on a surface of the first magnetic sheet 121S corresponding to the magnetic layer ML1 by using a printing machine (not shown) such as a screen printing machine or a gravure printing machine. Further, at the time of forming the conductor pattern C11, the conductor paste is filled in a through hole corresponding to the through hole V1. Then, the first magnetic sheet 121S is dried at a temperature of about 80 ° C for about 5 minutes using a dryer (not shown) such as a hot air dryer to form a first printed layer corresponding to the conductor pattern C11 in a specific arrangement.
The conductor patterns C12 to C17 and the via holes V2 to V6 were also produced in the same manner as described above. By this, the second to seventh printed layers corresponding to the conductor patterns C12 to C17 are formed in a specific arrangement on the surfaces of the second to seventh magnetic sheets 121S corresponding to the magnetic layers ML2 to ML7.
The composition of the conductor paste used herein is 85 wt% of the Ag particle group, 13 wt% of the butyl carbitol (solvent), 2 wt% of the polyvinyl butyral (adhesive), and d50 of the Ag particle group ( The median diameter) is about 5 μm.
(Production of the second magnetic layer)
Then, as shown in FIG. 6C, the second magnetic layer 122 is formed on the first to seventh magnetic sheets 121S.
When the second magnetic layer 122 is produced, first, soft magnetic alloy particles P2 having a coating material (third oxide film F23) containing a ruthenium oxide film formed on the surface thereof are prepared by performing the above pretreatment. Then, a magnetic paste (slurry) of a FeCrSi alloy particle group containing the soft magnetic alloy particles is applied to the first to seventh magnetic sheets by using a printing machine (not shown) such as a screen printing machine or a gravure printing machine. Around the conductor patterns C11 to C17 on the material 121S. Next, the magnetic paste is dried at about 80 ° C for about 5 minutes using a dryer (not shown) such as a hot air dryer.
The composition of the magnetic paste used herein was 85 wt% of the FeCrSi alloy particle group, 13 wt% of butyl carbitol (solvent), and 2 wt% of polyvinyl butyral (adhesive).
The thickness of the second magnetic layer 122 is adjusted so as to be equal to or smaller than the thickness of the conductor patterns C11 to C17, and substantially the same plane is formed in the lamination direction, so that the magnetic layers are not formed in the respective magnetic layers. The magnetic body portion 12 is obtained in the case where a step is generated and a build-up offset or the like is not generated. The second magnetic layer 122 is formed by a thickness in which three or more alloy magnetic particles (FeCrSi alloy particles) are arranged in the thickness direction. The thickness thereof is, for example, 4 μm or more and 20 μm or less. The average particle diameter of the soft magnetic alloy particles P2 constituting the second magnetic layer 122 may be the same as or smaller than or smaller than the average particle diameter of the soft magnetic alloy particles P1 constituting the first magnetic layer 121. In the present embodiment, the average particle diameter is 1 to 4 μm. When the average particle diameter of the soft magnetic alloy particles P2 is smaller, the specific surface area is increased, so that the insulating effect of the soft magnetic alloy particles P2 due to the second oxide F2 is increased.
The first to seventh sheets corresponding to the magnetic layers ML1 to ML7 are produced in the above manner (see FIG. 9C).
(Production of the third magnetic layer)
When the third magnetic layer 123 is produced, a magnetic paste (slurry) prepared in advance is applied to a base film made of plastic (not shown) by using a coater (not shown) such as a doctor blade or a die coater. ) the surface. Then, the base film is dried at a temperature of about 80 ° C for about 5 minutes using a dryer (not shown) such as a hot air dryer, and a magnetic sheet corresponding to the third magnetic layer 123 constituting the magnetic layers MLU and MLD is produced. . The magnetic sheets are each formed to have a size of a plurality of third magnetic layers 123.
The composition of the magnetic paste used herein was 85 wt% of the FeCrSi alloy particle group, 13 wt% of butyl carbitol (solvent), and 2 wt% of polyvinyl butyral (adhesive).
As described above, the thickness of each of the magnetic layers MLU and MLD is, for example, 50 μm or more and 120 μm or less, and is set according to the number of layers. In the present embodiment, the average particle diameter of the alloy magnetic particles constituting the third magnetic layer 123 and the average particle diameter of the alloy magnetic particles constituting the first magnetic layer 121 and the average particle diameter of the alloy magnetic particles constituting the second magnetic layer 122. The diameter is the same, or it may be larger or smaller. When the average particle diameter is the same, the relative magnetic permeability can be increased, and in the case of a small amount, the third magnetic layer 123 can be made thin.
(stacking and cutting)
Then, the first to seventh sheets (corresponding to the magnetic layers ML1 to ML7) and the eighth sheet group (corresponding to the magnetic layers MLU and MLD) are used in accordance with the drawing using an adsorption conveyor and a press (not shown). The order shown in 3 is laminated and thermocompression bonded to form a laminate.
Then, using a cutter (not shown) such as a cutter or a laser processing machine, the laminated body is cut into the size of the component body, and the wafer before processing (including the magnetic body portion and the coil portion before the heat treatment) is produced. .
(defatting and oxide formation)
Then, using a heat treatment machine (not shown) such as a baking furnace, a plurality of wafers before heat treatment are collectively heat-treated in an oxidizing atmosphere such as the atmosphere. The heat treatment includes a degreasing process and an oxide formation process, and the degreasing process is carried out at about 500 ° C for about 1 hour, and the oxide formation process is carried out at about 700 ° C for about 5 hours.
Before the heat treatment before the degreasing process, a plurality of fine gaps exist between the FeSiCr alloy particles in the magnetic body before the heat treatment, and a binder or the like is contained in the fine gap. However, these binders disappear in the degreasing process, so that the fine gap becomes pores (voids) after the degreasing process is completed. Further, a plurality of fine gaps are present between the Ag particles in the coil portion before the heat treatment, and a binder or the like is contained in the fine gap, but the binder disappears in the degreasing process.
In the oxide formation process after the degreasing process, the FeSiCr alloy particles in the magnetic body before the heat treatment are densely formed to form the magnetic body portion 12 (see FIGS. 1 and 2), and the particles are formed on the respective surfaces of the FeSiCr alloy particles. Oxide (first oxide F1 and second oxide F2). Moreover, the Ag portion of the coil portion before the heat treatment is sintered to form the coil portion 13 (see FIGS. 1 and 2), whereby the component body 11 is produced.
In the first magnetic layer 121, the first oxide F1 including the first to third oxide films F11 to F13 is formed on the surface of the soft magnetic alloy particles P1, and the soft magnetic particles P1 are bonded to each other via the joint portion V1. (Refer to Figure 5). On the other hand, in the second magnetic layer 122, the second oxide F2 including the first to fourth oxide films F21 to F24 is formed on the surface of the soft magnetic alloy particles P2, and the soft magnetic alloy particles P2 are formed via the joint portion V2. Combine with each other (refer to Figure 7).
(formation of external electrodes)
Then, using a coater (not shown) such as a dip coater or a roll coater, a conductor paste prepared in advance is applied to both end portions in the longitudinal direction of the component body 11, and a heat treatment machine such as a baking furnace is used (omitted As shown in the figure, the baking treatment is performed at about 650 ° C for about 20 minutes, and the solvent and the binder are eliminated by the baking treatment, and the Ag particles are sintered to prepare the external electrodes 14 and 15 (see Figure 1, Figure 2).
The composition of the conductor paste for the external electrodes 14 and 15 used herein is 85 wt% or more of the Ag particle group, and contains glass, butyl carbitol (solvent), and polyvinyl butyral (bonding) in addition to the Ag particle group. And the d50 (median diameter) of the Ag particle group is about 5 μm.
Finally, plating is performed. The plating is performed by ordinary plating, and the metal films of Ni and Sn are attached to the external electrodes 14 and 15 which are formed by sintering the Ag particles. In this way, the coil component 10 can be obtained.
In the coil component 10 of the present embodiment, the magnetic material constituting the second magnetic layer 122 has soft magnetic alloy particles P2 and a second oxide F2 formed on the surface thereof. In the magnetic material, the surface of the soft magnetic alloy particles P2 is covered with the first to fourth oxide films F21 to F24, so that the insulating properties higher than those of the magnetic material constituting the first magnetic layer 121 are obtained. Thereby, the insulation characteristics of the coil component 10 can be improved, and the large current can be easily handled.
Further, since the second magnetic layer 122 has higher insulating properties than the first magnetic layer 121, even if the distance between the soft magnetic alloy particles P2 is shortened, good insulating properties can be ensured. Therefore, even when the magnetic powder density (the relative density of the second magnetic layer 122) is increased to increase the magnetic properties, the required insulating properties can be stably ensured.
[Examples]
Hereinafter, embodiments of the invention will be described.
(Example 1)
It takes 50 minutes and will contain a specific amount of TEOS (tetraethoxy decane, Si (OC)₂ H₅ )₄ The treatment liquid of ethanol and water is added to the soft magnetic alloy particles (FeSiCr alloy particles) having an average particle diameter (D50) of 6 μm in an equal amount, and a mixture of a specific amount of ethanol and ammonia is mixed and stirred. Thereafter, the soft magnetic alloy particles are filtered and separated, and dried, whereby a SiO containing a thickness of 15 nm is formed on the surface.₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was prepared, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], dielectric breakdown voltage (BVD) [MV/cm], and strength [ Kgf/mm² ] for evaluation.
The production conditions of the green compact are as follows.
100 parts by weight of the alloy particles were stirred and mixed with 1.5 parts by weight of a PVA (polyvinyl alcohol) binder, and 0.5 parts by weight of Zn stearate was added as a lubricant. Thereafter, at 6 to 18 ton/cm² The forming pressure was formed into a shape for each of the following evaluations. At this time, the molding pressure was adjusted so that the filling ratio of the soft magnetic alloy particles in the magnetic body was 80 vol%. Then, the obtained green compact was degreased at 500 ° C for 1 hour, and heat-treated at 700 ° C for 5 hours in an atmosphere (in an oxidizing atmosphere) to obtain a magnetic body.
In order to measure the relative magnetic permeability (M), a ring-shaped magnetic body having an outer diameter of 8 mm, an inner diameter of 4 mm, and a thickness of 1.3 mm was produced. A coil containing a urethane-coated copper wire having a diameter of 0.3 mm was wound around the magnetic body to obtain a sample for measurement. The relative magnetic permeability of the magnetic body was measured at a measurement frequency of 10 MHz using an L Chronometer (manufactured by Agilent Technologies, Inc.: 4285A).
The volume resistivity was measured in accordance with JIS-K6911. Among them, a disk-shaped magnetic body having an outer shape of f7.0 mm and a thickness of 0.5 to 0.8 mm was produced as a measurement sample. After the above heat treatment, an Au film is formed on the two bottom surfaces (the entire surface of the bottom surface) by sputtering. A voltage of 3.6 V (60 V/cm) was applied to both surfaces of the Au film. The volume resistivity is calculated from the resistance value at this time.
In order to measure the dielectric breakdown voltage, a disk-shaped magnetic body having an outer shape of f7.0 mm and a thickness of 0.5 to 0.8 mm was produced as a measurement sample. After the above heat treatment, an Au film is formed on the two bottom surfaces (the entire surface of the bottom surface) by sputtering. A voltage was applied to both surfaces of the Au film, and an I-V measurement was performed. Slowly increase the applied voltage and the current density will be 0.01 A/cm.² The applied voltage at the time point is regarded as the breakdown voltage.
In order to evaluate the mechanical strength, a 3-point bending breaking stress was measured. Fig. 10 is a schematic explanatory view for explaining measurement of a three-point bending breaking stress. As shown in the figure, a load is applied to the object to be measured, and the load W when the object to be measured is broken is measured. The three-point bending breaking stress σb is calculated from the following equation in consideration of the bending moment M and the second moment I of the section.
Σb=(M/l)×(h/2)=3WL/2bh²
For the test piece for measuring the three-point bending breaking stress, a plate-shaped magnetic body having a length of 50 mm, a width of 10 mm, and a thickness of 4 mm was produced as a measurement sample.
The components and thicknesses of the oxide film (corresponding to the first to fourth oxide films F21 to F24 in FIG. 7) formed on the surface of the alloy particles in the magnetic material were measured. In the measurement, a STEM (scanning transmission electron microscope) equipped with EDS was used, and the composition of the oxide film was determined by the STEM-EDS method, and the STEM-high angle annular dark field (HAADF, high angle annular dark) was used. The field method measures the thickness of the oxide film. Before the measurement, a sheet sample was prepared by using a focused ion beam device (FIB) to form a sheet of 50 to 100 nm, and the diameter of the electron beam was in the range of 0.2 to 1.5 nm, respectively, by the line of EDS. The composition of the oxide film was measured by an analytical method, and the thickness of the oxide film was measured by the HAADF method. The place where the thickness of each oxide film is measured is performed in a portion where the alloy particles are not bonded to each other, and a perpendicular line is drawn to the surface of the alloy particles. Then, the surface of the alloy particles was observed to the outside on the vertical line, and the portion where the oxygen ratio was 5% or less was defined as the surface of the alloy particles. Further, when the surface of the alloy particles is viewed from the outside, the amount of the element L (Si, Zr, Hf or Ti) is larger than the element M (Cr or Al), and the oxide film (the first oxide film) of the element L is used. The thickness. Thereafter, the outer portion is observed in the same manner as the outer side, and the range of the element M is larger than the element L as the oxide film (the second oxide film) of the element M, and the amount of the element L is larger than the range of the element M. It is an oxide film (third oxide film) of the element L. Further, the oxide film (fourth oxide film) of Fe is in a range in which the amount of Fe is larger than that of the element L.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 27, and the volume resistivity is 2.7×10.³ [Ω・cm], insulation breakdown voltage is 1.3×10^-2 [MV/cm], intensity is 10 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 11 nm (component Cr), the thickness of the third oxide film is 15 nm (component Si), and the thickness of the fourth oxide film It is 20 nm (component Fe).
(Example 2)
It takes 10 minutes to contain a specific amount of TEOS (tetraethoxy decane, Si (OC)₂ H₅ )₄ ), the treatment liquid of ethanol and water is added to the mixture of soft magnetic alloy particles (FeSiCr alloy particles) having an average particle diameter (D50) of 6 μm, a specific amount of ethanol and ammonia water, and mixed and stirred. Filtering and separating the soft magnetic alloy particles and drying them, thereby forming a SiO containing a thickness of 1 nm on the surface.₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 36, and the volume resistivity is 7.1×10.¹ [Ω・cm], insulation breakdown voltage is 5.3×10^-3 [MV/cm], intensity is 14 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 11 nm (component Cr), the thickness of the third oxide film is 1 nm (component Si), and the thickness of the fourth oxide film It is 60 nm (component Fe).
(Example 3)
It takes 15 minutes and will contain a specific amount of TEOS (tetraethoxy decane, Si (OC)₂ H₅ )₄ ), the treatment liquid of ethanol and water is added to the mixture of soft magnetic alloy particles (FeSiCr alloy particles) having an average particle diameter (D50) of 6 μm, a specific amount of ethanol and ammonia water, and mixed and stirred. Filtering and separating the soft magnetic alloy particles and drying them, thereby forming a SiO containing a surface having a thickness of 5 nm.₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 34, and the volume resistivity is 3.2×10.² [Ω・cm], insulation breakdown voltage is 7.8×10^-3 [MV/cm], intensity is 12 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 11 nm (component Cr), the thickness of the third oxide film is 5 nm (component Si), and the thickness of the fourth oxide film It is 40 nm (component Fe).
(Example 4)
It takes 20 minutes to contain a specific amount of TEOS (tetraethoxy decane, Si (OC)₂ H₅ )₄ ), the treatment liquid of ethanol and water is added to the mixture of soft magnetic alloy particles (FeSiCr alloy particles) having an average particle diameter (D50) of 6 μm, a specific amount of ethanol and ammonia water, and mixed and stirred. Filtering and separating the soft magnetic alloy particles and drying them, thereby forming a SiO containing a thickness of 11 nm formed on the surface₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 30, and the volume resistivity is 3.2×10.² [Ω・cm], insulation breakdown voltage is 7.8×10^-3 [MV/cm], intensity is 11 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 11 nm (component Cr), the thickness of the third oxide film is 11 nm (component Si), and the thickness of the fourth oxide film It is 30 nm (component Fe).
(Example 5)
It takes 50 minutes to contain a specific amount of zirconium tetraisopropoxide and Zr (O-i-C).₃ H₇ )₄ The treatment liquid of ethanol and water is added dropwise to a mixture of soft magnetic alloy particles (FeSiCr alloy particles) having an average particle diameter (D50) of 6 μm, a specific amount of ethanol and ammonia water, and then mixed and stirred. The soft magnetic alloy particles are filtered and separated, and dried, whereby a ZrO containing a thickness of 15 nm is formed on the surface.₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 27, and the volume resistivity is 2.5×10.³ [Ω・cm], insulation breakdown voltage is 1.1×10^-2 [MV/cm], intensity is 10 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 11 nm (component Cr), the thickness of the third oxide film is 15 nm (component Zr), and the thickness of the fourth oxide film It is 20 nm (component Fe).
(Example 6)
It takes 50 minutes to contain a specific amount of tetraisopropoxy oxime, Hf[OCH(CH)₃ )₂ ]₄ The treatment liquid of ethanol and water is added dropwise to a mixture of soft magnetic alloy particles (FeSiCr alloy particles) having an average particle diameter (D50) of 6 μm, a specific amount of ethanol and ammonia water, and then mixed and stirred. The soft magnetic alloy particles are filtered and separated, and dried, whereby a surface containing 15 nm of HfO is formed.₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 26, and the volume resistivity is 2.4×10.³ [Ω・cm], insulation breakdown voltage is 1.2×10^-2 [MV/cm], intensity is 10 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 11 nm (component Cr), the thickness of the third oxide film is 15 nm (component Hf), and the thickness of the fourth oxide film It is 20 nm (component Fe).
(Example 7)
It takes 50 minutes to contain a specific amount of titanium tetraisopropoxide, Ti[OCH(CH)₃ )₂ ]₄ The treatment liquid of ethanol and water is added dropwise to a mixture of soft magnetic alloy particles (FeSiCr alloy particles) having an average particle diameter (D50) of 6 μm, a specific amount of ethanol and ammonia water, and then mixed and stirred. The soft magnetic alloy particles are filtered and separated, and dried, whereby a TiO containing a thickness of 15 nm is formed on the surface.₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 27, and the volume resistivity is 2.5×10.³ [Ω・cm], insulation breakdown voltage is 1.1×10^-2 [MV/cm], intensity is 10 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 11 nm (component Cr), the thickness of the third oxide film is 15 nm (component Ti), and the thickness of the fourth oxide film It is 20 nm (component Fe).
(Example 8)
It takes 50 minutes and will contain a specific amount of TEOS (tetraethoxy decane, Si (OC)₂ H₅ )₄ ), the treatment liquid of ethanol and water is added to the mixture of soft magnetic alloy particles (FeSiAl alloy particles) having an average particle diameter (D50) of 6 μm, a specific amount of ethanol and ammonia water, and mixed and stirred. Filtering and separating the soft magnetic alloy particles and drying them, thereby forming a SiO containing a thickness of 15 nm on the surface.₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 25, and the volume resistivity is 3.0×10.³ [Ω・cm], insulation breakdown voltage is 1.1×10^-2 [MV/cm], intensity is 11 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 15 nm (component Al), the thickness of the third oxide film is 15 nm (component Si), and the thickness of the fourth oxide film It is 20 nm (component Fe).
(Example 9)
It takes 50 minutes and will contain a specific amount of TEOS (tetraethoxy decane, Si (OC)₂ H₅ )₄ ), the treatment liquid of ethanol and water are added dropwise to the mixture of soft magnetic alloy particles (FeZrCr alloy particles) having an average particle diameter (D50) of 6 μm, a specific amount of ethanol and ammonia water, and then mixed and stirred. Filtering and separating the soft magnetic alloy particles and drying them, thereby forming a SiO containing a thickness of 15 nm on the surface.₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 27, and the volume resistivity is 2.0×10.³ [Ω・cm], insulation breakdown voltage is 1.1×10^-2 [MV/cm], intensity is 10 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Zr), the thickness of the second oxide film is 11 nm (component Cr), the thickness of the third oxide film is 15 nm (component Si), and the thickness of the fourth oxide film It is 20 nm (component Fe).
(Embodiment 10)
It takes 70 minutes and will contain a specific amount of TEOS (tetraethoxy decane, Si (OC)₂ H₅ )₄ ), the treatment liquid of ethanol and water are added dropwise to the mixture of soft magnetic alloy particles (FeZrCr alloy particles) having an average particle diameter (D50) of 6 μm, a specific amount of ethanol and ammonia water, and then mixed and stirred. Filtering and separating the soft magnetic alloy particles and drying them, thereby forming a SiO containing a thickness of 20 nm formed on the surface₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 25, and the volume resistivity is 4.1×10.³ [Ω・cm], insulation breakdown voltage is 1.1×10^-2 [MV/cm], intensity is 10 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 11 nm (component Cr), the thickness of the third oxide film is 20 nm (component Si), and the thickness of the fourth oxide film It is 20 nm (component Fe).
(Example 11)
It takes 90 minutes and will contain a specific amount of TEOS (tetraethoxy decane, Si (OC)₂ H₅ )₄ ), the treatment liquid of ethanol and water are added dropwise to the mixture of soft magnetic alloy particles (FeZrCr alloy particles) having an average particle diameter (D50) of 6 μm, a specific amount of ethanol and ammonia water, and then mixed and stirred. Filtering and separating the soft magnetic alloy particles and drying them, thereby forming a SiO containing a thickness of 24 nm on the surface.₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 21, and the volume resistivity is 5.0×10.³ [Ω・cm], insulation breakdown voltage is 8.0×10^-3 [MV/cm], intensity is 8 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 11 nm (component Cr), the thickness of the third oxide film is 24 nm (component Si), and the thickness of the fourth oxide film It is 15 nm (component Fe).
(Embodiment 12)
It takes 10 minutes to contain a specific amount of TEOS (tetraethoxy decane, Si (OC)₂ H₅ )₄ ), the treatment liquid of ethanol and water is added dropwise to the mixture of soft magnetic alloy particles (FeSiCr alloy particles) having an average particle diameter (D50) of 2 μm, a specific amount of ethanol and ammonia water, and then mixed and stirred. Filtering and separating the soft magnetic alloy particles and drying them, thereby forming a SiO containing a thickness of 1 nm on the surface.₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 21, and the volume resistivity is 8.0×10.¹ [Ω・cm], insulation breakdown voltage is 6.6×10^-3 [MV/cm], intensity is 12 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 11 nm (component Cr), the thickness of the third oxide film is 1 nm (component Si), and the thickness of the fourth oxide film It is 60 nm (component Fe).
(Example 13)
It takes 10 minutes to contain a specific amount of TEOS (tetraethoxy decane, Si (OC)₂ H₅ )₄ ), the treatment liquid of ethanol and water is added to the mixture of soft magnetic alloy particles (FeSiCr alloy particles) having an average particle diameter (D50) of 1 μm, a specific amount of ethanol and ammonia water, and mixed and stirred. Filtering and separating the soft magnetic alloy particles and drying them, thereby forming a SiO containing a thickness of 1 nm on the surface.₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 10, and the volume resistivity is 1.0×10.² [Ω・cm], insulation breakdown voltage is 1.2×10^-2 [MV/cm], intensity is 13 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 11 nm (component Cr), the thickness of the third oxide film is 1 nm (component Si), and the thickness of the fourth oxide film It is 60 nm (component Fe).
(Comparative example)
Will contain a specific amount of TEOS (tetraethoxy decane, Si (OC)₂ H₅ )₄ ), the ethanol and water treatment liquids are all mixed and stirred at one time to a soft magnetic alloy particle (FeSiCr alloy particle) having an average particle diameter (D50) of 6 μm, a specific amount of ethanol and ammonia water, and then filtered and separated. The soft magnetic alloy particles are dried and dried, thereby forming a SiO containing a thickness of 30 nm formed on the surface.₂ Soft magnetic alloy particles of the coating layer of the film. The pressed powder (magnetic material) of the soft magnetic alloy particles was produced under the same conditions as in Example 1, and the relative magnetic permeability (μ), volume resistivity [Ω·cm], and dielectric breakdown voltage of the soft magnetic alloy particles were prepared. (BVD) [MV/cm] and strength [kgf/mm² ] for evaluation.
The measurement results are shown in Tables 1 and 2. The relative magnetic permeability is 20, and the volume resistivity is 1.1×10.¹ [Ω・cm], insulation breakdown voltage is 7.0×10^-4 [MV/cm], intensity is 7 [kgf/mm² ]. Further, the thickness of the first oxide film is 5 nm (component Si), the thickness of the second oxide film is 11 nm (component Cr), and the thickness of the third oxide film is 71 nm, and the composition thereof is mainly composed of Fe and mixed. There are Si and Cr. Furthermore, the fourth oxide film could not be confirmed.
[Table 1]
[Table 2]
As shown in Tables 1 and 2, according to Examples 1 to 11 in which a coating material was formed by dropwise adding a treatment liquid to a solution of alloy particles at a specific amount, it was possible to mix the treatment liquid once to the treatment liquid. The comparative examples in which the coating material was formed in the above solution had higher dielectric breakdown characteristics and higher relative magnetic permeability. The reason for this is presumed to be that the third oxide film (coating material) is uniformly formed on the surface of the alloy powder, and although the thickness of the oxide film is thin, there is almost no defect. In addition, it is presumed that both the first oxide film and the third oxide film contribute to the dielectric breakdown characteristics, and the thickness of the entire first to fourth oxide films can be reduced.
Here, when the first embodiment is compared with the comparative example, the result is a pretreatment for forming a coating layer containing an Si oxide film on the alloy particles, and a mixture containing ethanol, ammonia water, TEOS, and water is used. The same is true. However, SiO formed on the surface of the alloy particles due to the preparation method of the mixed solution₂ The morphology of the membrane is quite different.
That is, in the treatment method of the comparative example in which alloy particles, ethanol, ammonia water, TEOS, and water are mixed at once, as described above, SiO₂ The particles nucleate in the solution, the crystal grains grow to form an aggregate, and the uniform nucleation of the aggregate adhering to the surface of the alloy particles predominates. The result is SiO₂ The fine particles do not cover the entire alloy particles and partially adhere to the surface, so that the insulation withstand voltage characteristics of the soft magnetic alloy particles cannot be improved.
Fig. 11 is a view schematically showing SiO formed on the surface of soft magnetic alloy particles in the case of a comparative example in which alloy particles, ethanol, ammonia water, TEOS, and water are mixed at once.₂ A cross-sectional view of the particle state of the microparticle. Furthermore, SiO is performed by preparing the above mixed solution.₂ In the case of formation of microparticles, SiO obtained by uniform nucleation and grain growth is performed using a high-resolution TEM of a magnification of about 50,000 times.₂ As a result of observation of the particles, for example, a streak-like pattern was observed to interfere with the grain. The interference pattern is a crystal grain, and since this phenomenon is observed, the aggregate obtained by the treatment method of the comparative example is crystalline.
On the other hand, according to the treatment method of Example 1 in which the treatment liquid containing TEOS, ethanol, and water was mixed and added to the mixed liquid containing the alloy particles, ethanol, and ammonia water, the uniform nucleation was suppressed. The uneven nucleation on the surface of the alloy particles predominates, so that even if the coating layer on the surface of the alloy particles is not as thick as 25 nm, it is formed in a stable and uniform thickness. By using this method, the thickness of the coating layer can be controlled in a single nanometer level by the amount of TEOS, and for example, even if it is a thickness of 1 nm, a stable coating film can be formed.
FIG. 12 is a cross-sectional view showing the state of the coating layer in the case where a coating layer is formed on the soft magnetic alloy particles by the first embodiment. Further, as a result of observing the coating layer formed in Example 1 using a high-resolution TEM having a magnification of 50,000 times, for example, no streaky pattern was observed in a stripe shape. Since the interference pattern was not observed, it was confirmed that the coating layer of Example 1 was amorphous. Usually amorphous SiO₂ Insulation resistance value is more crystalline than SiO₂ The resistance value is about 2 to 3 digits high. Therefore, the SiO coated in Example 1₂ Even if the film thickness is, for example, a thickness of 1 nm, it is possible to have higher insulation withstand voltage characteristics than the comparative example. Further, since the coating layers of Examples 1 to 11 have a thickness of 24 nm or less and are thin, iron (Fe) is stably diffused from the alloy particles to the outside of the coating layer by heat treatment to form a fourth oxide film. Thereby, further improvement in insulation characteristics can be achieved.
As described above, in Example 1 and Comparative Example 1, since the method of forming the oxide film as the pretreatment was greatly different, the film quality of the obtained oxide film was greatly different. The difference in film quality of the oxide film is reflected by the difference in insulation withstand voltage characteristics and strength of the pressed powder after heat treatment.
According to the above evaluation, Example 1 is more capable of improving the relative magnetic permeability than Example 8. It is predicted that the reason is that A1 is more likely to generate an oxidation reaction than Cr, and this influence slightly affects the filling rate after the heat treatment. The element M is preferably Cr in terms of being able to increase the relative magnetic permeability. Further, in the first embodiment, the dielectric breakdown characteristics can be improved as compared with the fifth and sixth embodiments. The reason for this is that even if it is an oxide film having the same thickness as Zr and Hf, the uniformity of the Si oxide film is high and it becomes an oxide film with few defects.
In particular, when the thickness of the first to fourth oxide films is the thickness of the first <third < fourth step (Examples 1, 4 to 9), the insulating property can be further improved. When the soft magnetic alloy particles of the same size are used as the third (first, fourth) (Examples 2 and 3), the relative magnetic permeability can be improved. The fourth oxide film is filled with voids generated by degreasing the binder, and even if the thickness thereof is increased, the relative magnetic permeability is not greatly reduced, and the strength can be improved by the effect of the landfill voids. Reduce water and other external soaking, thereby improving reliability. Moreover, it is understood that the first and second oxide films of Examples 5, 6, and 7 are composed only of the components of the soft magnetic alloy particles, and each oxide film is formed independently.
Further, in Example 11, it was observed that the relative magnetic permeability was further lowered as compared with Example 10, and slightly exceeded the value of the comparative example. It is predicted that this is due to excessive formation of the third oxide film. Further, in the examples herein, the thickness of the third oxide film is not made thinner than 1 nm. When it is less than 1 nm, a film covering the surface of the soft magnetic alloy particles cannot be formed. The oxide formed by the element L forming the third oxide film is predicted to have an oxide size of 0.5 nm or more, and since the oxide of this size is continuously arranged, an oxide film of 1 nm or more is required. Therefore, the third oxide film is preferably 1 nm or more and 20 nm or less.
Alloy particles of 6 μm were used for Example 2 having a thickness of 1 nm with respect to the third oxide film, and alloy particles of 2 μm and 1 μm were used for Examples 12 and 13, respectively. Although the relative magnetic permeability is lowered due to the refinement of the alloy particles, by the same method as in the second embodiment, the coating of a stable and uniform thickness as shown in Fig. 12 can be formed regardless of the particle diameter of the alloy particles. The layer can improve the dielectric breakdown characteristics. On the other hand, in the treatment method of the comparative example in which alloy particles, ethanol, ammonia water, TEOS, and water are mixed at once, by using SiO₂ The aggregate of particles adheres to the surface of the alloy particles to ensure dielectric breakdown characteristics, but if the alloy particles and SiO₂ When the difference in particle diameter of the particles is small, it is difficult to densely cover the surface of the alloy particles, and the dielectric breakdown characteristics cannot be improved.
Moreover, it was confirmed that the same insulating properties as those of the FeSiCr-based magnetic body were obtained even in the respective magnetic bodies of the FeSiAl-based or FeZrCr-based magnetic materials. Moreover, when the components of the coating material were Zr, Hf, and Ti, it was confirmed that the same insulating properties as those of the magnetic material having the coating material of the Si component were obtained.
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be added thereto.
For example, in the above embodiment, only the example in which the magnetic material of the present invention is applied to the second magnetic layer 122 has been described. However, the present invention is not limited thereto, and the present invention is also applicable to the first magnetic layer 121 and the third. At least two of the magnetic layer 123 or the first to third magnetic layers.
Further, in the above-described embodiment, the magnetic material constituting the magnetic core of the coil component or the laminated inductor is exemplified as the magnetic material. However, the present invention is not limited thereto, and the present invention can also be applied to a motor, A magnetic body used for electromagnetic parts such as actuators, generators, reactors, and turbulence.

10‧‧‧ coil parts

11‧‧‧Part body

12‧‧‧ Magnetic Department

13‧‧‧ coil department

13e1‧‧‧ lead end

13e2‧‧‧ lead end

14, 15‧‧‧ External electrodes

121‧‧‧1st magnetic layer

121S‧‧‧ Magnetic sheet

122‧‧‧2nd magnetic layer

123‧‧‧3rd magnetic layer

C11~C17‧‧‧ conductor pattern

F1‧‧‧oxide

F11‧‧‧1st oxide film

F12‧‧‧2nd oxide film

F13‧‧‧3rd oxide film

F2‧‧‧oxide

F21‧‧‧1st oxide film

F22‧‧‧2nd oxide film

F23‧‧‧3rd oxide film

F24‧‧‧4th oxide film

H‧‧‧ Height

L‧‧‧ length

ML1~ML17‧‧‧ magnetic layer

MLD‧‧‧ magnetic layer

MLU‧‧‧ magnetic layer

P1‧‧‧ soft magnetic alloy particles

P2‧‧‧ soft magnetic alloy particles

V1‧‧‧ Joint Department

V2‧‧‧ Joint Department

V3‧‧‧through hole

W‧‧‧Width

Fig. 1 is a perspective view showing a whole of a coil component according to an embodiment of the present invention.

Figure 2 is a cross-sectional view taken along line A-A of Figure 1.

Fig. 3 is an exploded perspective view of the component body of the above laminated inductor.

Figure 4 is a cross-sectional view taken along line B-B of Figure 1.

Fig. 5 is a cross-sectional view schematically showing a fine structure of an oxide film in a magnetic body constituting the first magnetic layer of the coil component.

Fig. 6 is a cross-sectional view schematically showing a laminated structure of an oxide film in a magnetic body constituting the first magnetic layer.

Fig. 7 is a cross-sectional view schematically showing a fine structure of an oxide film in a magnetic body constituting the second magnetic layer of the coil component.

Fig. 8 is a cross-sectional view schematically showing a laminated structure of an oxide film in a magnetic body constituting the second magnetic layer.

9A to 9C are schematic cross-sectional views showing a main part of a method of manufacturing a magnetic layer of the coil component.

Fig. 10 is a schematic view showing a method of measuring a three-point bending breaking stress.

Fig. 11 is a cross-sectional view showing the state of the SiO ₂ fine particles formed on the surface of the alloy particles by the method of the comparative example.

Fig. 12 is a cross-sectional view showing the state of a coating layer formed on the surface of the alloy particles by the method shown in the embodiment.

Claims (9)

A magnetic material having: a plurality of soft magnetic alloy particles, which include Fe, an element L (wherein the element L is any one of Si, Zr, and Ti) and an element M (wherein the element M is other than Si, Zr, Ti, and more Fe) Element that is easily oxidized); a first oxide film comprising an element L and covering the plurality of soft magnetic alloy particles; a second oxide film comprising an element M and covering the first oxide film; An amorphous third oxide film comprising an element L and covering the second oxide film; a fourth oxide film comprising Fe and covering the third oxide film; and The joint portion is composed of one of the fourth oxide films, and the plurality of soft magnetic alloy particles are bonded to each other. The magnetic material of claim 1, wherein The element M is Cr. The magnetic material of claim 1, wherein The element L is Si. The magnetic material of claim 2, wherein The element L is Si. The magnetic material of any one of claims 1 to 4, wherein The third oxide film has a thickness equal to or greater than the thickness of the first oxide film. The magnetic material of any one of claims 1 to 4, wherein The third oxide film has a thickness of 1 nm or more and 20 nm or less. The magnetic material of claim 5, wherein The third oxide film has a thickness of 1 nm or more and 20 nm or less. A magnetic material having: a plurality of soft magnetic alloy particles, which include Fe, an element L (wherein the element L is any one of Si, Zr, and Ti) and an element M (wherein the element M is other than Si, Zr, Ti, and more Fe) Element that is easily oxidized); a first oxide film comprising an element L and covering the plurality of soft magnetic alloy particles; a second oxide film comprising an element M and covering the first oxide film; An amorphous third oxide film comprising an element L and covering the second oxide film; The fourth oxide film contains Fe and covers the third oxide film. An electronic component comprising a magnetic core comprising the magnetic material according to any one of claims 1 to 8.