JP2017107935A - Dust core and magnetic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dust core having high magnetic permeability and a high withstand voltage and a magnetic element incorporating a coil having the same.SOLUTION: The dust core is composed of a composite of a binder and a metallic magnetic powder. The binder includes an epoxy resin having an ether skeleton represented by the following chemical formula. The metal magnetic powder is at least one kind selected from Fe-Ni type, Fe-Si-Al type, Fe-Si type, Fe-Si-Cr type and Fe type. The average particle diameter of the metal magnetic powder is 1 to 80 μm.SELECTED DRAWING: None

Description

  The present invention relates to a dust core in which metal magnetic particles are compression-molded and a magnetic element in which a coil is built in the dust core.

  In recent years, as represented by the smart phone / tablet PC field, miniaturization and high functionality of electrical devices are progressing. Accordingly, there is an increasing demand for miniaturization and high performance of the magnetic core. In the automotive field, the digitization of automobiles is rapidly progressing. Along with this, there is a growing demand for miniaturization and higher functionality of electrical components for automobiles. The use of soft magnetic metal materials is a material technology for small and high performance magnetic cores that are compatible with higher functionality of electronic equipment.

  In general, magnetic cores for magnetic application electronic parts such as inductors and reactors are formed by compression molding of sintered (ferrite) cores made by sintering soft magnetic ferrite particles and metal magnetic particles made of soft magnetic metal materials. The dust core produced is used. Here, the metal magnetic particles have a significantly higher saturation magnetic flux density than the soft magnetic ferrite particles. Therefore, the dust core is advantageous for downsizing compared to the sintered (ferrite) core. In addition, a dust core produced by compression molding metal magnetic particles does not easily reach magnetic saturation even when a large direct current is superimposed. Therefore, it is advantageous to cope with a large current of the magnetic core, which is essential for enhancing the functionality of electronic equipment.

  However, since the metal magnetic particles have a lower electrical resistivity than the ferrite particles, the loss due to the eddy current increases. Therefore, the heat loss of the powder magnetic core formed by compression molding the metal magnetic particles is also large. That is, an electronic device using a dust core has a large energy loss as the frequency increases. As described above, using a dust core in an electronic device goes against the trend of energy saving in the electronic device.

  Unlike a sintered (ferrite) magnetic core, a dust core is not formed by bonding between particles. Therefore, it is difficult to ensure the strength of the magnetic core required as an electronic component, and a bonding method that increases the bonding strength between particles is also required.

  In order to reduce the loss due to eddy current of metal magnetic particles and to secure the magnetic core strength, an organic or inorganic insulating layer is generally provided on the metal magnetic particles, and an organic or inorganic insulating binder called a binder. After the coating, the solidification by compression molding, joining, heating, etc. is performed to produce a dust core.

  Here, in order to achieve miniaturization and high performance of the dust core, it is important to increase the filling rate of the metal magnetic particles per unit volume, that is, the core density. High relative permeability can be achieved by increasing the magnetic core density.

  As a method for improving various properties such as magnetic permeability by increasing the magnetic core density, Patent Document 1 discloses that a surface of pure iron powder including iron oxide is entirely or partially covered with an insulating layer, A method for coating a silicone resin thereon is described.

  Patent Document 2 describes a method in which a lubricant is present between metal magnetic particles.

  However, the withstand voltage of the dust cores described in Patent Documents 1 and 2 is a problem. In particular, when a dust core is used for a coil-embedded magnetic element, it is important to improve the withstand voltage.

  In Patent Document 3, the withstand voltage is improved by a method of increasing the binder in the powder magnetic core, a method of increasing the insulating layer on the surface of the metal magnetic particles, or a method of having an insulating filler between the metal particles. Is described.

  However, the magnetic permeability of the dust cores using these methods is greatly reduced. And when the magnetic permeability decreases, the inductance of the magnetic element decreases.

JP 2006-233295 A JP 2011-29605 A International Publication No. 2010/103709

  An object of the present invention is to provide a dust core having a high magnetic permeability and a high withstand voltage, and a coil-embedded magnetic element including the dust core.

  The present inventors paid attention to the binder in the dust core in the study of the dust core optimum for magnetic applied electronic parts such as an inductor, which is a coil-embedded magnetic element. As a result of examining the composition, chemical structure and physical properties of the binder in detail, it has been found that a powder magnetic core having a high magnetic permeability and a high withstand voltage can be obtained by using a binder containing a specific type of epoxy resin. Furthermore, the present inventors have found that the dust core is useful for magnetic applied electronic parts such as an inductor, which is a magnetic element with a built-in coil.

  The dust core of the present invention is a dust core including a binder and metal magnetic powder, and the binder includes an epoxy resin having an ether skeleton represented by the following chemical formula.

  In the dust core of the present invention, the metal magnetic powder is at least one kind of metal magnetic powder among Fe—Ni, Fe—Si—Al, Fe—Si, Fe—Si—Cr, and Fe. It is preferable to contain.

  The average particle diameter of the metal magnetic powder is preferably 1 to 80 μm.

  The filling rate of the metal magnetic powder is preferably 60 to 90% by volume.

  The magnetic element of the present invention is a magnetic element in which a coil is built in the dust core.

  ADVANTAGE OF THE INVENTION According to this invention, a high magnetic permeability and a high withstand voltage powder magnetic core and a magnetic element using the same can be provided. Furthermore, it is possible to provide an electronic component such as a small-sized, high-function, high-reliability inductor made of the magnetic element.

  Furthermore, according to the present invention, a compact, high-characteristic and high-reliability dust core can be produced, and magnetic applied electronic parts such as inductors using the magnetic core as a coil-embedded magnetic element are widely distributed, so that tablets, smartphones, etc. As a result, the market will expand and the industry will grow. In addition, since it can be widely applied to applications such as automobiles and social infrastructure, where high reliability is indispensable, the market will expand and grow as an industry.

FIG. 1 is an enlarged schematic view of a dust core precursor before pressing. FIG. 2 is an enlarged schematic view of the dust core precursor after pressurization. FIG. 3 is an enlarged schematic view of the dust core. 4A is an external perspective view of a winding (coil) built-in type inductor according to one embodiment of the present invention, and FIG. 4B is a winding (coil) built in the inductor shown in FIG. 4A. FIG.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the present invention is not limited to this embodiment. Further, the dust core in the present embodiment is a magnetic core formed by compression molding metal magnetic powder containing metal magnetic particles made of a soft magnetic metal material.

  An enlarged schematic view of the powder magnetic core precursor 1a according to the present embodiment is shown in FIG. The dust core precursor 1 a includes granules 4 composed of metal magnetic particles 2 and a binder 3. The granule 4 is manufactured by mixing and integrating the metal magnetic particles 2 and the binder 3. Here, the binder 3 contains at least an epoxy resin having an ether skeleton represented by the following chemical formula.

  Here, an epoxy resin having an ether skeleton represented by the above chemical formula will be described. The ether skeleton has a portion in which two benzene rings are ether-bonded and a portion in which a benzene ring and an epoxy group are ether-bonded. In the benzene ring in the ether skeleton, an oxygen atom of an ether bond is bonded to the carbon at the para position, and a hydrogen atom is bonded to the other carbon.

  The epoxy resin having an ether skeleton represented by the above chemical formula is an epoxy resin obtained by polymerizing the ether skeleton.

  FIG. 2 shows an enlarged schematic view of the dust core precursor 1b pressed from the direction of the arrow with respect to the dust core precursor 1a. As shown in FIG. 2, in the dust core precursor 1b, the arrangement of the metal magnetic particles 2 is changed from the dust core precursor 1a. That is, the metal magnetic particles 2 are rearranged by pressurization. In the present application, the rearrangement of the particles means that the particles move by pressurization and the particles approach the closest packed state.

  The binder 3 contained in the dust core precursor 1a is made of a soft uncured or semi-cured epoxy resin. This is to facilitate rearrangement of the metal magnetic particles 2 during pressurization.

  It is essential that the binder 3 of the dust core precursor 1a according to this embodiment includes an epoxy resin having an ether skeleton represented by the above chemical formula. When the binder 3 of the powder magnetic core precursor 1a includes an epoxy resin containing the chemical structure of the ether skeleton represented by the following chemical formula 1, the binder 3 of the powder magnetic core precursor 1b is also an epoxy resin having an ether skeleton. including.

  When using a binder containing an epoxy resin having an ether skeleton represented by the above chemical formula in the precursor 1a for a dust core, using only a binder not containing an epoxy resin having an ether skeleton represented by the above chemical formula As compared with, the pressurization can cause rearrangement of the metal magnetic particles 2 easily and with high efficiency. And the powder magnetic core precursor 1b with high density and high magnetic permeability can be provided. The above phenomenon occurred because the epoxy resin having an ether skeleton acted like a lubricant between metal magnetic particles.

  In addition, about the epoxy resin used for a binder, you may use the epoxy resin which has the ether skeleton shown in said chemical formula with resin other than the epoxy resin which does not have the ether skeleton shown in said chemical formula, or an epoxy resin. The ratio of the epoxy resin having an ether skeleton represented by the above chemical formula to the entire epoxy resin used for the binder is preferably 20% by weight or more, and particularly preferably 50% by weight or more. By setting the ratio of the epoxy resin having an ether skeleton represented by the above chemical formula within the above range, a powder magnetic core having a high withstand voltage is likely to be obtained.

  Moreover, there is no restriction | limiting in particular in the average molecular weight of the epoxy resin used for a binder, However, It is preferable to set it as 100-3000. By setting the average molecular weight within the above range, a powder core having a high magnetic permeability is likely to be obtained.

  FIG. 3 shows an enlarged schematic view of the dust core 1c obtained by forming the dust core precursor 1b and performing a treatment such as thermosetting as necessary. The powder magnetic core 1c including the epoxy resin having the ether skeleton represented by the above chemical formula in the binder 3 has a higher withstand voltage than the powder magnetic core not including the epoxy resin having the ether skeleton represented by the above chemical formula. ing. The withstand voltage here refers to a voltage at which a current exceeding a specified value flows when a voltage is applied to the dust core. In addition, ensuring the voltage resistance is indispensable in the automobile field where high reliability is required. In addition, since the binder 3 contained in the granule 4 of the dust core precursor 1b is integrated by a process such as molding and thermosetting, the granule 4 is not observed in the dust core 1c.

  The binder 3 is made of known inorganic particles (inorganic filler) such as alumina, silica, boron nitride (BN), magnesium oxide, organic or inorganic lubricants, phenolic or amine epoxy curing agents, imidazole, etc. One or more curing accelerators, organic solvents, flexible agents such as silicone and acrylic, ion-trapping substances such as hydrotalcite compounds, adhesion-imparting agents, dispersants, stabilizers, colorants, anti-settling agents, etc. Multiple may be included.

  Further, as the metal magnetic powder containing the metal magnetic particles 2, Fe-based alloy, Fe-Si-based alloy, Fe-Si-Cr-based alloy, Fe-Ni-based alloy (permalloy-based alloy), Fe-Si-Al-based alloy ( A powder obtained by combining one type or a plurality of types of sendust alloy), amorphous metal, and the like can be preferably used. In the present application, pure iron having a metal content other than Fe of 2% by weight or less is also included in the Fe-based alloy.

  In addition, the above-described alloys may contain inevitable impurities. The content of inevitable impurities is preferably 1% by weight or less.

  When the Fe—Si based alloy powder is used for the metal magnetic powder, the content of each component is preferably such that the Si content is 1 wt% or more and 8 wt% or less, and the balance is composed of Fe and inevitable impurities. More preferably, the Si content is 2 wt% or more and 6.5 wt% or less. When the Si content is 1% by weight or more, the magnetic anisotropy tends to be small, and the magnetic permeability can be easily increased. Further, when the Si content is 8% by weight or less, the hardness of the metal magnetic particles 2 tends to be high, and the metal magnetic particles 2 and the granules 4 are appropriately deformed at the time of pressure molding, whereby the powder magnetic core precursor is preliminarily deformed. It is easy to increase the density of the body 1b and the dust core 1c, and the magnetic permeability tends to increase.

  When Fe-Si-Cr alloy powder is used for the metal magnetic powder, the content of each component is as follows: Si content is 1 to 8% by weight, Cr content is 2 to 8% by weight And the balance is preferably composed of Fe and inevitable impurities. More preferably, the Si content is 2 wt% or more and 6.5 wt% or less, and the Cr content is 2 wt% or more and 5 wt% or less. When the Si content is 1% by weight or more, the magnetic anisotropy tends to be small, and the magnetic permeability can be easily increased. Further, when the Si content is 8% by weight or less, the hardness of the metal magnetic powder tends to be high, and the metal magnetic particles 2 and the granules 4 are appropriately deformed at the time of pressure molding, whereby the powder magnetic core precursor. It is easy to increase the density of the magnetic core 1c and the magnetic permeability 1b. Further, when the Cr content is 2% by weight or more, the corrosion resistance tends to be improved. When the content of Cr is 8% by weight or less, it is easy to achieve high magnetic permeability.

  When Fe-Ni alloy powder (permalloy alloy powder) is used for the metal magnetic powder, the content of each component is Ni content of 30 wt% or more and 85 wt% or less, and the balance is Fe and inevitable impurities It is desirable to consist of. More preferably, the Ni content is 40 wt% or more and 80 wt% or less. When the Ni content is 85% by weight or more, it tends to be a low magnetic permeability magnetic core. Further, when the Ni content is 30% by weight or less, a powder core having a low magnetic permeability tends to be obtained.

  When Fe-Si-Al-based alloy powder (Sendust-based alloy powder) is used for the metal magnetic powder, the content of each component is 5 to 15% by weight of Si and 2% by weight of Al. % To 8% by weight, and the balance is preferably composed of Fe and inevitable impurities. More preferably, the Si content is 7 wt% or more and 12 wt% or less, and the Al content is 4 wt% or more and 6 wt% or less. When the Si content is 15% by weight or more, a hard and brittle material tends to be obtained. In addition, when the Si content is 5% by weight or less, it tends to be a material with a large loss. Further, when the Al content is 8% by weight or more, it is likely to be a hard and brittle material. If the Al content is 2% by weight or less, it tends to be a material with a large loss.

  When an Fe-based alloy is used for the metal magnetic powder, it is desirable that the inevitable impurities are 1% by weight or less and the balance is made of only Fe. The amount of inevitable impurities is more preferably 0.5% by weight or less. By reducing the content of inevitable impurities, a material with a high saturation magnetic flux density is likely to be obtained.

Further, the metal magnetic particles 2 are formed by chemical conversion treatment such as phosphoric acid treatment, treatment with a coupling agent for increasing the affinity with the binder 3, and BN, SiO ₂ , MgO, Al ₂ O for obtaining high insulation. Surface treatment by inorganic substance coating of ₃ etc. or organic substance coating may be made.

  The average particle size of the metal magnetic particles 2 is preferably 1 to 80 μm. When the average particle diameter is 1 μm or more, the surface energy of the metal magnetic particles is less likely to be excessive, the metal magnetic particles are less likely to aggregate, flow, and rearrange, and the packing density in the dust core 1c is constant. It is maintained above, and the magnetic permeability tends to be improved. Moreover, when the average particle diameter is 80 μm or less, the contact area between particles due to particle deformation during compaction is unlikely to be excessive, and the withstand voltage is less likely to decrease due to the increase in contact area. The average particle diameter is more preferably in the range of 1 to 60 μm, and still more preferably in the range of 5 to 40 μm. The average particle diameter here is a value of a particle diameter having a cumulative degree of 50% (so-called D50) in the cumulative particle size distribution.

  Moreover, as for the powder magnetic core 1c in this embodiment, it is desirable for the filling rate of the metal magnetic particle 2 to be 60 volume% or more and 90 volume% or less. When the filling rate of the metal magnetic particles 2 is 60% by volume or more, the molding density tends to be a certain level or more, and the magnetic permeability is difficult to decrease. In addition, when the filling rate of the metal magnetic powder 2 is 90% by volume or less, the volume occupied by the binder 3 is maintained at a certain level or more, so that the withstand voltage is easily maintained at a certain level or more. The filling rate is more preferably 70% by volume or more and 90% by volume or less. More preferably, it is 80 volume% or more and 90 volume% or less. The filling rate of the metal magnetic particles 2 can be adjusted by changing the ratio of the amount of the metal magnetic particles 2 and the binder 3 used.

  Although the above description is based on the premise that the shape of the metal magnetic particles 2 is an indefinite shape, the shape of the metal magnetic particles 2 may be spherical. Further, a plurality of spherical metal magnetic particles 2 and irregular metal magnetic particles 2 may be used in combination. By using the spherical metal magnetic particles 2, the withstand voltage of the dust core 1c can be further improved.

  The term “spherical” as used herein means that 50% of the cumulative circularity distribution of the metal magnetic particles 2 observed on the fracture surface of the dust core 1c is the average circularity (D50), and the average circularity (D50) is 0.00. The case where it is 90 or more. An indefinite shape means a case where the average circularity (D50) is less than 0.90. The circularity is calculated by the following relational expression from a known method such as image analysis of a fracture surface.

(Circularity) = 4πS / L ²
S: Area of circular object L: Length of contour line of circular object

  Further, the average circularity (D50) of the spherical metal magnetic particles 2 is preferably 0.95 or more for further improving the withstand voltage.

  Hereinafter, although the manufacturing method of the powder magnetic core 1c which concerns on this embodiment is demonstrated, the manufacturing method of the powder magnetic core 1c is not limited to the following method.

  First, a metal magnetic powder containing metal magnetic particles is prepared. Although this embodiment demonstrates the manufacturing method of the metal magnetic powder by a gas atomizing method, another method can also be used.

  An alloy having a composition suitable for the metal composition of the target metal magnetic particles is prepared. And metal magnetic powder is manufactured by performing the gas atomization method with respect to an alloy. Further, classification can be performed, and the average particle diameter (D50) and the average circularity (D50) can be controlled.

  Next, a paint containing a binder is prepared. In addition to the binder, the coating material may contain a binder curing agent, a binder curing catalyst, and a solvent, or may contain other additives.

  The binder in this embodiment should just contain the epoxy resin which has ether skeleton shown to said chemical formula.

  As the binder curing agent, a curing agent generally used in this technical field can be used. For example, a phenol curing agent or an amine curing agent can be used. Further, it is not necessary to use a binder curing agent. Although there is no restriction | limiting in particular in content of a hardening | curing agent, Preferably it is 20 to 80 weight% with respect to 100 weight% of binders. By setting the content of the curing agent within the above range, a high withstand voltage powder magnetic core is obtained.

  As a curing catalyst for the binder, a curing catalyst generally used in this technical field can be used. For example, 2-ethyl-4-methylimidazole, 2-phenylimidazole, etc. can be used. Further, it is not necessary to use a binder curing catalyst. Although there is no restriction | limiting in particular in content of a curing catalyst, Preferably it is 0.5 to 5 weight% with respect to 100 weight% of binders. By setting the content of the curing catalyst within the above range, a high withstand voltage dust core is obtained.

  There is no restriction | limiting in particular in the kind of solvent, The solvent generally used in this technical field can be used. For example, a methyl ethyl ketone solvent, a methyl isobutyl ketone solvent, etc. are mentioned. Moreover, there is no restriction | limiting in particular in the density | concentration of each component, such as a binder in a solvent.

  Examples of other additives include fillers and rust preventives. Other additives may not be used. Although there is no restriction | limiting in particular in content of another additive, Preferably it is 10 to 60 weight% in total with respect to 100 weight% of binders.

  Next, the metal magnetic powder and the paint are mixed and kneaded to prepare a powder magnetic core precursor. There is no particular limitation on the mixing and kneading method. For example, mixing and kneading may be performed using a kneader, a planetary mixer, or the like.

  Next, the obtained powder magnetic core precursor is compression molded to obtain a molded body. There is no particular limitation on the compression molding method. The molding pressure can be, for example, 100 to 800 MPa.

  Furthermore, the obtained molded body is thermally cured to obtain a dust core. There are no particular restrictions on the conditions for thermosetting. For example, thermosetting can be performed at 130 to 200 ° C. for 1 to 5 hours.

  Although there is no restriction | limiting in particular in the use of the powder magnetic core 1c which concerns on this embodiment, For example, there exists the coil built-in type magnetic element 10 shown in FIG. The magnetic element 10 with a built-in coil has a dust core 11 shown in FIG. The dust core portion 11 is composed of a dust core 1c. And the dust core part 11 has the coil 12 shown in FIG.4 (b) inside.

  The coil-embedded magnetic element manufactured using the dust core 1c is smaller in size and more functional (particularly inductance) and more reliable (particularly withstand voltage) than a conventional coil-embedded magnetic element.

  Moreover, the dust core 1c and the coil-embedded magnetic element 10 according to the present embodiment can be used for magnetic applied electronic components such as an inductor, a reactor, and a non-contact power feeding coil. These magnetic application electronic parts are effective in miniaturization, high functionality and high reliability.

  Hereinafter, the present invention will be described in detail by showing examples according to the present invention. Moreover, this invention is not limited to a present Example, unless it deviates from the summary.

<Example 1>
First, metal magnetic powder was prepared. The metal magnetic powder was produced from an alloy containing Fe—Si based alloy particles by a gas atomization method and further classified. As a result, the average particle diameter (D50) = 29 μm, the average circularity (D50) = 0.81, and the metal composition (element composition) is Fe / Si = 93.5 wt% / 6.5 wt%. A system alloy powder was obtained.

  Next, a bifunctional ether type epoxy resin (YSLV-80DE manufactured by Nippon Steel & Sumikin Chemical) was prepared as a binder. In the following description, a bifunctional ether type epoxy resin (YSLV-80DE manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) may be referred to as “resin A”.

  As a binder curing agent, 50 parts by weight of phenol novolak resin (TD-2131 made by DIC) as a phenol curing agent was prepared with respect to 100 parts by weight of the binder. In the following description, a phenol novolac resin (TD-2131 manufactured by DIC) may be referred to as a resin E.

  Furthermore, 1 part by weight of 2-ethyl-4-methylimidazole (2E4Mz manufactured by Shikoku Kasei) was prepared as a curing catalyst with respect to 100 parts by weight of the binder.

  The above binder, curing agent and curing catalyst were dissolved in a methyl ethyl ketone solvent to prepare a paint.

  The powder magnetic core precursor was produced by mixing the Fe—Si alloy powder and the paint and kneading them using a kneader. The mixing ratio was 3 parts by weight of binder with respect to 100 parts by weight of Fe-Si based alloy powder.

  Next, the precursor was compression-molded using a mold at a molding pressure of 400 MPa to form a toroidal shaped body having an outer diameter of 11 mm, an inner diameter of 6.5 mm, and a height of 3 mm. Finally, thermosetting was performed at 175 ° C. for 1 hour, and a dust core having a filling ratio of Fe—Si based alloy powder of 80% by volume was produced.

  In addition, except that it is molded into a cylindrical molded body having a diameter of 10 mm and a height of 5 mm, compression molding and thermosetting are performed in the same manner as the above-described toroidal powder magnetic core, and a withstand voltage measurement test piece is prepared. Produced.

  Hereinafter, the measurement method and evaluation criteria of the characteristics of the dust core will be described.

  The magnetic permeability of the dust core was calculated from the inductance obtained by winding a toroidal dust core to form a closed magnetic circuit and exciting it at 50 mV at 100 kHz. In this example, the case where the magnetic permeability was 25 or more was considered good.

  With respect to the withstand voltage of the dust core, a voltage was applied using a source meter above and below the test piece for withstand voltage measurement, and the voltage value at which a current of 1 mA flowed was taken as the withstand voltage. In this example, the case where the withstand voltage was 400 V or higher was considered good.

  Table 1 shows the characteristics of the dust core of Example 1. The magnetic permeability was 28.5, the withstand voltage was 520 V, and all the characteristics were good.

<Comparative Example 1>
The same procedure as in Example 1 was performed except that the resin A was changed to a bifunctional biphenyl type epoxy resin (YX-4000 manufactured by Mitsubishi Chemical Corporation) having a substituent on the side chain of the mesogen skeleton. The results are shown in Table 1. The magnetic permeability was 29.8, the withstand voltage was 60 V, and the withstand voltage was poor. In the following description, a bifunctional biphenyl type epoxy resin (YX-4000 manufactured by Mitsubishi Chemical Corporation) having a substituent in the side chain of the mesogen skeleton may be referred to as a resin B.

<Comparative example 2>
The same procedure as in Example 1 was performed except that the resin A was changed to a dicyclopentadiene type epoxy resin (HP-7200 manufactured by DIC). The results are shown in Table 1. The permeability was 23.2, the withstand voltage was 80V, and the permeability and withstand voltage were poor. In the following description, dicyclopentadiene-type epoxy resin (HP-7200 manufactured by DIC) may be referred to as resin C.

<Comparative Example 3>
The same procedure as in Example 1 was performed except that the resin A was changed to an ortho-cresol novolac epoxy resin (N695 made by DIC). The results are shown in Table 1. The permeability was 24.3, the withstand voltage was 100 V, and the permeability and withstand voltage were poor. In the following description, an ortho-cresol novolac type epoxy resin (N695 made by DIC) may be referred to as a resin D.

  As described above, when the epoxy resin (resin A) having an ether skeleton represented by the following chemical formula is applied to the dust core precursor and the binder of the dust core from Example 1 and Comparative Examples 1 to 3, other resins are used. Compared with the case of applying (resin B to resin D), the magnetic permeability and the withstand voltage are greatly improved.

<Example 1a>
About the resin used for a binder, it implemented similarly to Example 1 except having changed into the mixed resin which mixed resin A and resin D by resin A: resin D = 50 weight%: 50 weight%. The results are shown in Table 1. The magnetic permeability was 28.2, the withstand voltage was 570 V, and all the characteristics were good. As mentioned above, even if it is a mixed resin of an epoxy resin having an ether skeleton represented by the following chemical formula and other resins, it is possible to obtain a dust core having greatly improved permeability and withstand voltage.

<Example 2>
The same operation as in Example 1 was performed except that the composition of the Fe—Si based alloy powder was changed to a metal composition of Fe / Si = 95.5 (wt%) / 4.5 (wt%). The results are shown in Table 2. The magnetic permeability was 29.3, the withstand voltage was 480 V, and all the characteristics were good.

<Example 3>
The same operation as in Example 1 was performed except that the composition of the Fe—Si based alloy powder was changed to a metal composition of Fe / Si = 97.0 (wt%) / 3.0 (wt%). The results are shown in Table 2. The magnetic permeability was 31.2, the withstand voltage was 560 V, and all the characteristics were good.

  As described above, when the epoxy resin (resin A) having an ether skeleton represented by the above chemical formula is applied to the dust core precursor and the binder of the dust core from Examples 1 to 3, the Fe-Si alloy powder Even when Fe / Si was changed, the magnetic permeability and withstand voltage were good.

<Example 4>
Except for changing the Fe-Si alloy powder to Fe-Si-Cr alloy powder of Fe / Si / Cr = 88.5 (wt%) / 6.5 (wt%) / 5 (wt%). This was carried out in the same manner as in Example 1. The results are shown in Table 3. The magnetic permeability was 26.5, the withstand voltage was 460 V, and all the characteristics were good.

<Example 5>
Except for changing the Fe-Si alloy powder to Fe-Si-Cr alloy powder of Fe / Si / Cr = 90.5 (wt%) / 4.5 (wt%) / 5 (wt%) This was carried out in the same manner as in Example 1. The results are shown in Table 3. The magnetic permeability was 28.8, the withstand voltage was 550 V, and all the characteristics were good.

<Example 6>
Except for changing the Fe-Si alloy powder to Fe-Si-Cr alloy powder of Fe / Si / Cr = 92 (wt%) / 3.5 (wt%) / 4.5 (wt%) This was carried out in the same manner as in Example 1. The results are shown in Table 3. The magnetic permeability was 30.3, the withstand voltage was 570 V, and all the characteristics were good.

  As described above, when the epoxy resin (resin A) having an ether skeleton represented by the above chemical formula is applied to the dust core precursor and the binder of the dust core from Examples 1 and 4 to 6, Fe—Si—Cr As in the case of the Fe—Si alloy composition, the magnetic permeability and the withstand voltage were good even in the alloy composition of the alloy type.

<Example 7a>
It implemented like Example 1 except the point which changed the Fe-Si type alloy powder into the Fe-Ni type alloy powder (permalloy powder). The results are shown in Table 4. The magnetic permeability was 29.4, the withstand voltage was 580 V, and all the characteristics were good.

<Example 7b>
It implemented like Example 1 except the point which changed the Fe-Si type alloy powder into the Fe-Si-Al type alloy powder (Sendust powder). The results are shown in Table 4. The magnetic permeability was 27.2, the withstand voltage was 520 V, and all the characteristics were good.

<Example 7c>
Example 1 except that the Fe—Si based alloy powder was changed to Fe based alloy powder (iron powder) and the average particle size (D50) = 4 μm and the average circularity (D50) = 0.91. It carried out similarly. The results are shown in Table 4. The magnetic permeability was 25.3, the withstand voltage was 450 V, and all the characteristics were good. In the present application, the Fe-based alloy powder is a metal powder having a total content of metal elements other than Fe of 2% by weight or less. Therefore, Fe metal powder not containing any metal element other than Fe is also included in the Fe-based alloy powder.

<Comparative Example 7a>
Except that resin A was changed to resin D, the same procedure as in Example 7a was performed. The results are shown in Table 4. The magnetic permeability was 23.2, the withstand voltage was 210V, and the permeability and withstand voltage were poor.

<Comparative Example 7b>
The same operation as in Example 7b was performed except that the resin A was changed to the resin D. The results are shown in Table 4. The permeability was 22.5, the withstand voltage was 190V, and the permeability and withstand voltage were poor.

<Comparative Example 7c>
Except that resin A was changed to resin D, the same procedure as in Example 7c was performed. The results are shown in Table 4. The permeability was 20.5, the withstand voltage was 90V, and the permeability and withstand voltage were poor.

  As described above, from Examples 7a to 7c and Comparative Examples 7a to 7c, when the epoxy resin (resin A) having an ether skeleton represented by the above chemical formula is applied to the dust core precursor and the binder of the dust core, Even in the case of powder, sendust powder and iron powder, the magnetic permeability and withstand voltage were good as in the case of Fe-Si alloy powder. Further, when the resin D was applied instead of the resin A, the magnetic permeability and the withstand voltage were greatly reduced.

<Example 8>
The same operation as in Example 1 was performed except that the average particle diameter of the Fe—Si based alloy powder was changed from 29 μm to 1 μm. The results are shown in Table 5. The magnetic permeability was 25.2, the withstand voltage was 520 V, and all the characteristics were good.

<Example 9>
The same operation as in Example 1 was performed except that the average particle diameter of the Fe—Si based alloy powder was changed from 29 μm to 5 μm. The results are shown in Table 5. The magnetic permeability was 25.8, the withstand voltage was 500 V, and all the characteristics were good.

<Example 10>
The same operation as in Example 1 was performed except that the average particle size of the Fe—Si based alloy powder was changed from 29 μm to 40 μm. The results are shown in Table 5. The magnetic permeability was 30.5, the withstand voltage was 530 V, and all the characteristics were good.

<Example 11>
The same operation as in Example 1 was performed except that the average particle size of the Fe—Si based alloy powder was changed from 29 μm to 60 μm. The results are shown in Table 5. The magnetic permeability was 32.3, the withstand voltage was 500 V, and all characteristics were good.

<Example 12>
The same operation as in Example 1 was performed except that the average particle size of the Fe—Si based alloy powder was changed from 29 μm to 80 μm. The results are shown in Table 5. The magnetic permeability was 34.6 and the withstand voltage was 420 V. All characteristics were good.

  As described above, when the epoxy resin (resin A) having an ether skeleton represented by the above chemical formula is applied to the dust core precursor and the binder of the dust core from Examples 1 and 8 to 12, the Fe-Si alloy Even when the average particle diameter of the powder was changed, the magnetic permeability and withstand voltage were good.

<Example 15>
It was carried out in the same manner as in Example 1 except that the mixing ratio of the Fe—Si based alloy powder and the paint was changed so that the filling rate of the Fe—Si based alloy powder in the dust core was 60% by volume. . The results are shown in Table 6. The magnetic permeability was 25.8, the withstand voltage was 490 V, and all the characteristics were good.

<Example 16>
It was carried out in the same manner as in Example 1 except that the mixing ratio of the Fe—Si based alloy powder and the paint was changed so that the filling rate of the Fe—Si based alloy powder in the dust core was 90% by volume. . The results are shown in Table 6. The magnetic permeability was 27.1, the withstand voltage was 530 V, and all the characteristics were good.

  As described above, when the epoxy resin (resin A) having an ether skeleton represented by the above chemical formula is applied to the dust core precursor and the binder of the dust core from Examples 1, 15, and 16, the Fe-Si alloy Even if the filling rate of the powder is changed, the magnetic permeability and the withstand voltage are good.

<Example 18>
The same operation as in Example 1 was performed except that the average circularity of the Fe—Si based alloy powder in the dust core was set to 0.91. The results are shown in Table 7. The magnetic permeability was 27.8, and the withstand voltage was 610 V. Compared with Example 1, the withstand voltage was further improved.

<Example 19>
It implemented like Example 1 and 18 except having set the average circularity of the Fe-Si type alloy powder in a dust core to 0.97. The results are shown in Table 7. The magnetic permeability was 28.2, and the withstand voltage was 700 V. The withstand voltage was further improved as compared with Examples 1 and 18.

  Of the resins A to E, the resin A is the only epoxy resin having an ether skeleton represented by the above chemical formula.

  As is apparent from Tables 1 to 7, a compact formed from a binder containing an epoxy resin (resin A) having an ether skeleton represented by the above chemical formula, and metal magnetic particles such as Fe-Si alloy powder. The magnetic core has a high magnetic permeability and a high withstand voltage. Therefore, magnetic applied electronic parts such as inductors and reactors using the dust core have high characteristics and high reliability.

<Inductor characteristics of Example 1 and Comparative Example 1>
Furthermore, using the powder magnetic core in Example 1 of the present invention, an inductor (6.5 mm × 6.5 mm × 2.5 mm thick, copper wire winding number 8 turns) in which the winding (coil) is built in the powder magnetic core ) Was produced. In addition, using the dust core in Comparative Example 1, an inductor (6.5 mm × 6.5 mm × 2.5 mm thickness, copper wire winding number 8 turns) in which a winding (coil) is built in the dust core is manufactured. did. The inductor characteristics (inductance and withstand voltage between terminals) of these inductors were measured. Inductance was measured at 50 kHz and 100 mV. With respect to the withstand voltage between terminals, a voltage was applied between the terminals of the inductor, and a voltage value at which a current of 1 mA flowed was defined as the withstand voltage.

  Table 8 shows the inductor characteristics of the inductor using the dust core of Example 1 and the inductor using the dust core of Comparative Example 1. Compared with the inductance of the inductor using the dust core of Comparative Example 1 being 3.2 μH, the inductance of the inductor using the dust core of Example 1 was 3.8 μH. That is, the inductor using the dust core of Example 1 had a higher inductance than the inductor using the dust core of Comparative Example 1. Regarding the withstand voltage between terminals, the inductor using the dust core of Comparative Example 1 was 80 V, whereas the inductor using the dust core of Example 1 was 1100 V, and the pressure of Example 1 was Compared with the inductor using the powder magnetic core of Comparative Example 1, the withstand voltage between terminals of the inductor using the powder magnetic core was significantly improved. As described above, the inductor with a built-in coil (coil-embedded magnetic element) using the dust core with high permeability and high withstand voltage according to the present invention has high performance and high reliability.

1a Powder magnetic core precursor (before pressurization)
1b Powder magnetic core precursor (after pressurization)
1c Dust Core 2 Metallic Magnetic Powder 3 Binder 4 Granule 10 Coil Built-in Magnetic Element 11 Dust Core 12 Coil

Claims (5)

A dust core containing a binder and metal magnetic powder,
The powder magnetic core according to claim 1, wherein the binder includes an epoxy resin having an ether skeleton represented by the following chemical formula.

  The said metal magnetic powder contains at least 1 or more types of metal magnetic powder among Fe-Ni type | system | group, Fe-Si-Al type | system | group, Fe-Si type | system | group, Fe-Si-Cr type | system | group, and Fe type | system | group. Powder magnetic core.   The powder magnetic core according to claim 1 or 2, wherein the metal magnetic powder has an average particle diameter of 1 to 80 µm.   The powder magnetic core according to claim 1, wherein a filling rate of the metal magnetic powder is 60 to 90% by volume. The magnetic element which has the dust core in any one of Claims 1-4, and the coil incorporated in the said dust core.

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