JP5913246B2 - Metal magnetic materials, electronic components - Google Patents

Description

  The present invention relates to a metal magnetic material and an electronic component used for a power inductor used in a power supply circuit.

  Power inductors used in power supply circuits are required to be small, low loss, and capable of handling large currents. To meet these demands, a metal magnetic material with a high saturation magnetic flux density is used as the magnetic material. It is being considered. The metal magnetic material has an advantage that the saturation magnetic flux density is high, but the insulation resistance of the material itself is low, and in order to use it as a magnetic body of an electronic component, it is necessary to ensure insulation between the material particles. If insulation cannot be ensured, the component body will become conductive, material properties will deteriorate, and product loss will increase.

Conventionally, when a metal magnetic material is used for an electronic component, bonding between the resin particles or the like or coating the particles with an insulating film has ensured insulation between the material particles.
For example, Patent Document 1 describes an electronic component in which a material obtained by coating the surface of an Fe—Cr—Si alloy with ZnO-based glass is fired under vacuum, oxygen-free, and low oxygen partial pressure. However, under vacuum, oxygen-free, and low oxygen partial pressure, to prevent sintering, it is necessary to ensure the coating, it is necessary to increase the amount of glass added, and the cost increases due to the coating. There's a problem.
As described above, in the conventional method of bonding with resin or coating particles with an insulating film, it is necessary to increase the amount of insulating material other than the magnetic material in order to further ensure insulation. However, there is a problem that increasing the volume other than the magnetic material leads to deterioration of magnetic properties.

  Moreover, the technique which forms the layer of the oxide derived from a raw material is disclosed (patent document 2, patent document 3). In this method, since the insulating film of the oxide derived from the raw material is used, the deterioration of the magnetic characteristics is small. However, the insulating film of oxide derived from the raw material used in this method may have low insulating properties or may not have sufficient strength.

  Therefore, a method of forming a raw material-derived oxide layer and impregnating it with a resin is also disclosed (Patent Document 4). However, methods such as impregnation have not been practical because they increase costs and lack product stability.

  Further, Patent Document 5 discloses a magnetic layer material containing a core-structure metal magnetic powder in which an iron-based compound is a core and a metal compound shell is formed around the core, and glass. However, in this method, in order to construct the core-shell structure, it is necessary to coat the shell forming material on the material constituting the core, and as with the conventional method of coating the above-described particles with an insulating film, the cost is low. There is a problem that the magnetic properties are deteriorated due to an increase in the amount of coating material (shell forming material).

  In a metal magnetic material for electronic parts, it is necessary to insulate magnetic particles with a minimum insulating layer to ensure high insulation. The insulating film needs to be strong electrically and mechanically. However, any of the above prior arts has some unsolved problems as described above.

JP 2010-62424 A Japanese Patent No. 4866971 Japanese Patent No. 5082002 JP 2012-238841 A JP 2013-33966 A

  An object of the present invention is to provide a metal magnetic material that can be reliably insulated and has a high saturation magnetic flux density, and an electronic component that uses this metal magnetic material and has low loss and good DC superimposition characteristics. .

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.

The invention of claim 1 is a metal magnetism containing iron, silicon and chromium, a metal magnetic alloy powder not treated for forming a metal oxide on its surface, and zinc. An element body (11, 21) is formed using a material, and by heating the element body, zinc is deposited on the surface of the metal magnetic alloy powder, and the metal magnetic alloy powders in the element body , attached through the zinc coil in said body (12a, 12b, 12c, 22) that is formed, a method of manufacturing an electronic component (10, 20), characterized in.

The invention according to claim 2 is a metal magnetism containing iron, silicon and chromium, a metal magnetic alloy powder not treated for forming a metal oxide on its surface, and zinc. An element body (11, 21) is formed using a material, and by heat-treating the element body, zinc-based ferrite is precipitated on the surface of the metal magnetic alloy powder, and the metal magnetic alloy powder in the element body A method for producing an electronic component (10, 20) , characterized in that the elements are bonded to each other via the zinc-based ferrite and coils (12a, 12b, 12c, 22) are formed in the element body. .

Invention of Claim 3 is a manufacturing method of the electronic component (10,20) of Claim 1 or Claim 2 whose volume resistivity of the said element | base_body (11,21) is 10 < ⁷ > ohm * cm or more. .

Invention of Claim 4 is a manufacturing method of the electronic component (10, 20) of any one of Claim 1 to Claim 3 whose bending strength of the said element | base_body (11,21) is 30 Mpa or more. It is.

According to a fifth aspect of the present invention, the metal magnetic alloy powders in the element body (11, 21) are bonded to the surface via another material constituting the element body without interposing a metal oxide. It is a manufacturing method of the electronic component (10, 20) of any one of Claim 1 to Claim 4 which has a part.

  According to the present invention, the metal magnetic material is a mixture of iron, silicon, metal magnetic alloy powder containing chromium, and zinc. Accordingly, the metal magnetic material can be reliably insulated and can be a material having a high saturation magnetic flux density. In addition, an electronic component using this metal magnetic material can have low loss and good direct current superposition characteristics.

1 is a perspective view showing a first embodiment of an electronic component 10 according to the present invention. 1 is an exploded perspective view of an electronic component 10 according to the present invention. It is the table | surface which put together and showed the composition of the Example and comparative example which performed the comparative test, and the comparative test result. FIG. 2 is an X-ray diffraction pattern of a mixture of raw material powder, a binder removal treatment (here, 400 ° C.), and a heat treatment performed at 800 ° C. It is a photograph which shows Zn distribution of the material cross section after heat processing at 800 degreeC. It is a perspective view which shows 2nd Embodiment of the electronic component 20 by this invention. 2 is a cross-sectional view of an electronic component 20.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a perspective view showing a first embodiment of an electronic component 10 according to the present invention.
FIG. 2 is an exploded perspective view of the electronic component 10 according to the present invention. In FIG. 2, the external terminals 13 and 14 are omitted.
In addition, each figure shown below including FIG. 1 is the figure shown typically, and the magnitude | size and shape of each part are exaggerated suitably for easy understanding.
In the following description, specific numerical values, shapes, materials, and the like are shown and described, but these can be changed as appropriate.

The electronic component 10 is a multilayer inductor that includes an element body 11 and external terminals 13 and 14.
As shown in FIG. 2, the element body 11 has metal magnetic layers 11a, 11b, 11c, and 11d, and coil conductor patterns 12a, 12b, and 12c.

The metal magnetic layers 11a to 11d are formed of a metal magnetic material in which metal magnetic alloy powder and zinc are mixed.
The metal magnetic alloy powder is a powder of a metal magnetic alloy (so-called Fe—Cr—Si based metal magnetic alloy) containing iron (Fe), silicon (Si), and chromium (Cr) as a metal magnetic body. is there. In the element body 11 (the metal magnetic layers 11a to 11d), zinc-based ferrite is deposited on the surface of the metal magnetic alloy powder, and the metal magnetic alloy powders in the element body 11 pass through the zinc-based ferrite. Are combined. Details of the metal magnetic material forming the metal magnetic layers 11a to 11d will be described later.

  The coil conductor patterns 12a to 12c are formed by using a conductor paste in which a metal material such as silver, silver, gold, gold, copper, or copper is made into a paste.

A coil conductor pattern 12a is formed on the surface of the metal magnetic layer 11a. The coil conductor pattern 12a is formed with less than one turn. One end of the coil conductor pattern 12 a is drawn to the end face of the metal magnetic layer 11 a and is connected to the external terminal 13.
A coil conductor pattern 12b is formed on the surface of the metal magnetic layer 11b. The coil conductor pattern 12b is formed for less than one turn. One end of the coil conductor pattern 12b is connected to the other end of the coil conductor pattern 12a via a conductor in the through hole of the metal magnetic layer 11b.
A coil conductor pattern 12c is formed on the surface of the metal magnetic layer 11c. The coil conductor pattern 12c is formed with less than one turn. One end of the coil conductor pattern 12c is connected to the other end of the coil conductor pattern 12b via a conductor in the through hole of the metal magnetic layer 11c. The other end of the coil conductor pattern 12 c is drawn to the end face of the metal magnetic layer 11 c and connected to the external terminal 14.
On the metal magnetic layer 11c on which the coil conductor pattern 12c is formed, a metal magnetic layer 11d for protecting the coil conductor pattern is formed.
Here, in order to facilitate understanding, four metal magnetic layers are used, but the number of turns of the coil pattern may be increased by increasing the number of layers.

  Thus, the coil pattern is formed in the element body 11 by the coil conductor patterns 12a to 12c between the metal magnetic layers. The coil conductor patterns 12a to 12c are connected between the external terminal 13 and the external terminal 14 formed on both end faces of the element body (molded body) 11 as shown in FIG.

  The electronic component 10 of the present embodiment having the above-described configuration is manufactured as follows. First, a predetermined amount of ZnO (zinc oxide) additive is added to an Fe—Cr—Si alloy powder having a predetermined composition, and then mixed, and a binder such as PVA (polyvinyl alcohol) is further added. And this is knead | mixed and it is made a paste and a metal magnetic material paste is obtained. Further, a conductor paste for forming the coil conductor patterns 12a to 12c is separately prepared. An element body (molded body) 11 is obtained by printing the metal magnetic material paste and the conductor paste alternately in layers. The obtained element body 11 is subjected to binder removal processing and heat treatment at a predetermined temperature, whereby the electronic component 10 is obtained. The external terminals 13 and 14 can be formed after heat treatment, for example. In this case, for example, the external terminals 13 and 14 can be provided by applying a conductive paste for external terminals to both ends of the heat-treated body 11 and then performing heat treatment.

  In the present embodiment, as described above, the metal magnetic material used for the metal magnetic layers 11a to 11d constituting the element body 11 is a mixture of a metal magnetic alloy powder and a ZnO additive, Coexistence of magnetic characteristics and insulation characteristics is achieved. Hereinafter, more specific examples of this metal magnetic material will be described with reference to comparative test results including comparative examples.

FIG. 3 is a table summarizing the compositions of Examples and Comparative Examples in which comparative tests were performed and the results of the comparative tests.
In the comparative test, two examples according to the present invention were prepared, and five comparative examples were prepared.
In this comparative experiment, a predetermined amount of additives shown in FIG. 3 was added to a powder of an Fe—Cr—Si alloy having a predetermined composition, and then mixed, and a binder such as PVA was further added, and this was kneaded. An element body (molded body) was formed using a material paste, a binder (degreasing) treatment was performed at 400 ° C. to 600 ° C., and then a heat treatment was performed at 800 ° C. to produce an inductor. Note that the Fe—Cr—Si alloy powder is not subjected to a treatment for forming a metal oxide on its surface. That is, the Fe—Cr—Si alloy powder itself, which has not been subjected to special treatment, is used.

  In the metal magnetic materials of Example 1 and Example 2, by adding ZnO, the insulation resistance is increased and the bending strength is also increased as compared with the case of no addition (Comparative Examples 3, 4, and 5). .

  Moreover, also about magnetic characteristics, such as complex permeability (micro | micron | mu) ', the metallic magnetic material of Example 1 and Example 2 is equivalent to the case where it does not add (Comparative Example 3, 4, 5) by adding ZnO. Performance is secured.

In the comparative test results shown in FIG. 3, the decrease in complex permeability μ ′ with no addition is within 20%, the volume resistivity is 10 ⁷ Ω · cm or more, and the bending strength is 30 Mpa. The determination results are shown in the determination column as “Yes” for the above and “No” for the others. This condition is set as a minimum condition that can be used as an inductor. The metal magnetic materials of Example 1 and Example 2 satisfy the above conditions and are “OK”. From this result, in order to satisfy the above conditions, it has been obtained that ZnO requires an addition amount of 1.0 wt% or more and 2.0 wt% or less.
On the other hand, in the comparative examples 3 to 5 to which the non-added product of the comparative example, the borosilicate glass having a high softening point, or NiO which is an oxide other than ZnO was added, characteristics satisfying the above conditions were not obtained. The reason for this is considered to be related to the formation temperature of Zn ferrite.
In Comparative Example 1 and Comparative Example 2, ZnO was added in the same manner as in Example, but the addition amount was out of the range of 1.0 wt% or more and 2.0 wt% or less, and such an addition amount is insufficient. Or, when the amount of addition is excessive, since the bending strength is lowered, it is judged as impossible and is used as a comparative example.

It can be confirmed by X-ray diffraction or SEM-EDX that Zn ferrite is formed on the surface of the Fe—Cr—Si alloy by adding ZnO.
FIG. 4 shows an X-ray diffraction pattern of a mixture of raw material powder, a binder removal treatment (here, 400 ° C.), and a heat treatment at 800 ° C. when the metal magnetic material of Example 2 is used. FIG. In FIG. 4, the reference position of the vertical axis (intensity) is shifted so that the three types of diagrams do not overlap.
A ZnO peak is observed at 2θ = 30 to 40 in both the case where the raw materials are mixed and the case after the binder removal. However, when the heat treatment is performed at 800 ° C., the ZnO peak disappears, and the spinel ferrite (ZnFe ₂ O ₄ ) peak appears instead. This change is not confirmed in the sample without Zn addition.

  For the coil conductor patterns 12a to 12c, for example, a metal such as silver (Ag) can be used. However, these metals are subjected to a heat treatment at a temperature of 800 ° C. or higher, so that the sintering proceeds and the resistance value is increased. Can be lowered. However, if the heat treatment temperature is less than 800 ° C., the metal does not sinter and the resistance value remains high. The heat treatment is performed in a state where the coil pattern is formed in the molded body by the coil conductor patterns 12a to 12c. Therefore, even if the heat treatment is performed by raising the temperature to 800 ° C. necessary for the heat treatment of the metal of the coil conductor patterns 12a to 12c, the magnetic permeability of the metal magnetic layers 11a to 11d is maintained at a necessary value. is necessary.

FIG. 5 is a photograph showing the Zn distribution of the material cross section after heat treatment at 800 ° C. when the metal magnetic material of Example 2 was used. Fig.5 (a) is a photograph by SEM, FIG.5 (b) is a photograph by SEM-EDX of the same site | part as Fig.5 (a). The portion displayed in white in FIG. 5B is a portion where Zn exists.
Referring to FIG. 5, Zn is segregated and precipitated between the surface of the particles and is not present inside the particles. That is, it can be confirmed that Zn ferrite is formed on the particle surface.

  In addition, as in Comparative Example 1 and Comparative Example 2, there may be a case where the result of adding ZnO cannot be obtained. Therefore, when using the metal magnetic material containing ZnO of the present invention, the optimum amount of addition may be set according to the particle diameter of the metal material and the temperature at which heat treatment is performed. As the particle size of the metal magnetic alloy powder increases, the amount of ZnO required decreases (surface area decreases). Also, the amount of addition should be adjusted when raising the heat treatment temperature.

  As described above, according to the first embodiment, the metal magnetic material in which the metal magnetic alloy powder containing iron, silicon, and chromium and zinc are mixed is used. Therefore, even if the electronic component 10 of the first embodiment is heat-treated at a heat treatment temperature necessary for reducing the resistance value of the conductor, sufficient magnetic permeability can be secured, low loss, and good DC superposition characteristics. A high-performance multilayer inductor can be obtained. Moreover, in 1st Embodiment, the process of coating etc. for forming a metal oxide in the surface with respect to the metal magnetic alloy powder is unnecessary, and can simplify a manufacturing process.

(Second Embodiment)
FIG. 6 is a perspective view showing a second embodiment of the electronic component 20 according to the present invention.
FIG. 7 is a cross-sectional view of the electronic component 20.
The electronic component 20 of the second embodiment is a winding type inductor including an element body 21 and a coil 22. Since the electronic component 20 of the second embodiment differs in the manufacturing method, the form and material of the coil 22 are different from those of the first embodiment. On the other hand, the metal magnetic material forming the element body 21 is the same as the metal magnetic material forming the metal magnetic layers 11a to 11d of the first embodiment.
Therefore, the same reference numerals are given to the portions that perform the same functions as those in the first embodiment described above, and repeated descriptions are omitted as appropriate.

The coil 22 is configured by spirally winding a rectangular conducting wire having a rectangular cross section with edgewise winding. The coil 22 may be a conductive wire having a coating, or may be an uncoated conductive wire because the element body 21 has an insulating property if not tightly wound.
The periphery of the coil 22 is covered with an element body 21 formed of a metal magnetic material in which metal magnetic alloy powder and zinc are mixed.
Further, both ends of the coil 22 are drawn from the end face of the element body 21 and are bent to the bottom face.

The electronic component 20 of the present embodiment having the above-described configuration is manufactured as follows.
First, a predetermined amount of an additive (ZnO) is added to an Fe—Cr—Si alloy powder having a predetermined composition, and then mixed, and a binder such as PVA is further added. And this is granulated and a metal magnetic material is obtained. The coil 22 is formed in a predetermined shape.
Next, powder of a metal magnetic material mixed in the resin binder is injected into the mold in which the coil 22 is housed, and pressure is applied to the powder to form the element body 21.
Next, the element body 21 is subjected to binder removal processing at a temperature of about 400 ° C. in the atmosphere, and then heat-treated at, for example, 800 ° C. to obtain the electronic component 20.

  As described above, according to the second embodiment, the same effect as that of the first embodiment can be obtained for the wound electronic component 20.

(Deformation)
The present invention is not limited to the embodiment described above, and various modifications and changes are possible, and these are also within the scope of the present invention.

(1) In each embodiment, the specific example of the composition of the metal magnetic material has been described. However, the present invention is not limited to this, and the amount of each component (configuration ratio) depends on the particle diameter of the magnetic material and desired magnetic characteristics. You may change suitably according to etc.

(2) In each embodiment, the temperature at which the heat treatment is performed has been described with a specific example. However, the temperature is not limited to this, and the temperature at which the heat treatment is performed is appropriately changed according to the particle diameter of the magnetic material, desired magnetic characteristics, and the like. May be.

(3) In each embodiment, the additive added to the metal magnetic material has been described with an example of being Zno. For example, the additive may include an oxide containing ZnO, a compound of Zn, Zn-based ferrite, and the like.

(4) In each embodiment, the metal magnetic alloy powder contained in the metal magnetic material has been described as having no oxide formed on the surface thereof. For example, an oxide may be formed on the surface of the metal magnetic alloy powder. The metal magnetic alloy powder naturally oxidizes or oxidizes in a high-temperature heat treatment, and the metal oxide derived from the metal magnetic alloy powder is, for example, partially or entirely on the surface. It may form naturally. In the present invention, the insulation by the metal oxide derived from the metal magnetic alloy powder is not expected, but there is no problem even if the metal oxide is formed on the surface of the metal magnetic alloy powder.

(5) In each embodiment, the example in which zinc is deposited on the surface of the metal magnetic alloy powder has been described. For example, in addition to zinc, a mixture of elements constituting the metal magnetic alloy powder may be further deposited on the surface of the metal magnetic alloy powder. In connection with this, the metal magnetic alloy powders in the element body may be bonded via a mixture of zinc and an element constituting the metal magnetic alloy powder.

  Each and the modified embodiments can be used in appropriate combination, but detailed description is omitted. Further, the present invention is not limited by the embodiments described above.

DESCRIPTION OF SYMBOLS 10 Electronic component 11 Element body 11a, 11b, 11c, 11d Metallic magnetic material layer 12a, 12b, 12c Conductor pattern 13, 14 for coil External terminal 20 Electronic component 21 Element body 22 Coil

Claims (5)

A metal magnetic alloy powder containing iron, silicon, and chromium, which has not been treated to form a metal oxide on its surface ;
With zinc,
An element body is formed using a metal magnetic material mixed with
By heat-treating the element body, zinc is deposited on the surface of the metal magnetic alloy powder ,
Metal magnetic alloy powders in the element body are bonded via the zinc ,
A coil is formed in the element body ;
A method of manufacturing an electronic component characterized by the above. A metal magnetic alloy powder containing iron, silicon, and chromium, which has not been treated to form a metal oxide on its surface ;
With zinc,
An element body is formed using a metal magnetic material mixed with
By heat-treating the element body, zinc-based ferrite is precipitated on the surface of the metal magnetic alloy powder ,
Metal magnetic alloy powders in the element body are bonded via the zinc-based ferrite ,
A coil is formed in the element body ;
A method of manufacturing an electronic component characterized by the above. The method for manufacturing an electronic component according to claim 1, wherein the volume resistivity of the element body is 10 ⁷ Ω · cm or more. The method for manufacturing an electronic component according to any one of claims 1 to 3, wherein the bending strength of the element body is 30 MPa or more. Magnetic metal alloy powder particles in the element body, of claims 1 to 4 having a portion which is connected via the other material constituting the body without passing through the metal oxide on the surface thereof The manufacturing method of the electronic component of any one of Claims 1 .