Composite magnetic material compositions, magnetic members, and electronic components

Abstract

To provide a highly reliable magnetic member which has good heat resistance and can suppress deterioration of characteristics over a long period of time, a composite magnetic body composition constituting the magnetic member, and an electronic component having the magnetic member.SOLUTION: A composite magnetic body composition 10 has a binder 14 containing a bisphenol type epoxy resin in which molecule rotation is suppressed, and a plurality of magnetic particles 12 bonded to each other by the binder 14.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a composite magnetic material composition that constitutes a magnetic member used as part of a magnetic application type of electronic component, such as an inductor, reactor, transformer, non-contact power supply coil, magnetic shield, etc.

Background Art

[0002] As a representative example of a magnetic member used as part of a magnetic application type of electronic component, a compacted powder core is known. The compacted powder core is used, for example, as a magnetic core such as an inductor. The compacted powder core is obtained, for example, by pressure molding a compacted powder core precursor containing granules of a composite magnetic material composition in which a plurality of magnetic particles are bound by a binder resin.

[0003] For example, in electronic components placed in a high-temperature environment, heat resistance is particularly required. Under such circumstances, as shown in, for example, Patent Document 1 or Patent Document 2 below, a resin having a high glass transition temperature (Tg) has been proposed as the binder resin contained in the magnetic member used for electronic components.

[0004] However, resins having a high glass transition temperature generally have low thermal decomposition resistance, and there is a problem that characteristic deterioration tends to occur when left at a high temperature for a long time. For example, in magnetic members used for in-vehicle applications where a high degree of reliability is required, it is required to be able to suppress characteristic deterioration over a long period at high temperatures.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] This invention has been made in view of the above circumstances, and its object is to provide a highly reliable magnetic member that has good heat resistance and can suppress deterioration of its properties over a long period of time, a composite magnetic composition constituting the magnetic member, and an electronic component having the magnetic member. [Means for solving the problem]

[0007] To achieve the above objective, the composite magnetic material composition according to the present invention is The device comprises a binder containing a bisphenol-type epoxy resin with suppressed molecular rotation, and a plurality of magnetic particles bound together by the binder.

[0008] The inventors diligently studied highly reliable magnetic materials that exhibit good heat resistance and suppress degradation of properties over long periods. As a result, they discovered that a composite magnetic material composition consisting of a specific resin and magnetic particles improves the reliability of magnetic materials, leading to the completion of the present invention.

[0009] Preferably, the bisphenol-type epoxy resin has an amide structure within its molecule. Preferably, the bisphenol-type epoxy resin has a plurality of aromatic rings having a conjugated structure. The bisphenol-type epoxy resin may also have a plurality of aromatic rings having a conjugated structure in its imide structure.

[0010] Preferably, the magnetic particles include metallic magnetic particles. In particular, the inventors have confirmed that a combination of metallic magnetic particles and a specific epoxy resin can suppress the deterioration of properties over long periods in high-temperature environments. It is possible that the metallic magnetic particles exert some kind of negative catalytic effect in relation to the specific binder resin.

[0011] Preferably, the metallic magnetic particles have at least amorphous metal. Preferably, the metallic magnetic particles have at least pure Fe. Preferably, the magnetic particles are spherical.

[0012] The magnetic member of the present invention has a composite magnetic composition as described in any of the above. The electronic component of the present invention has the magnetic member as described above. The magnetic member is not particularly limited, but for example, a compacted magnetic core is exemplified. The compacted magnetic core may have a coil inside it. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic cross-sectional view of an electronic component relating to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram of magnetic material-containing granules (composite magnetic material composition) used to manufacture the element body (pressed magnetic core) of the electronic component shown in Figure 1. [Figure 3] Figure 3 is a graph showing the change in the degree of degradation of the binder resin alone used in the examples and comparative examples of the present invention. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below.

[0015] As shown in Figure 1, the inductor 2 as an electronic component according to an embodiment of the present invention has an element body 4 that is substantially rectangular parallelepiped (substantially hexahedral).

[0016] The element body 4 has an upper surface 4a, a bottom surface 4b located on the opposite side of the upper surface 4a in the Z-axis direction, end surfaces 4c and 4d located on opposite sides along the X-axis, and side surfaces (not shown) located on opposite sides along the Y-axis.

[0017] A pair of terminal electrodes 8 are formed on the bottom surface 4b of the element body 4. The pair of terminal electrodes 8 are formed separated in the X-axis direction and insulated from each other. Each terminal electrode 8 is formed to be continuous not only on the bottom surface 4b of the element body 4, but also on the end surfaces 4c and 4d located nearby.

[0018] In the inductor 2 of the present embodiment, an external circuit can be connected to these terminal electrodes 8 via wiring or the like not shown. Further, the inductor 2 can be mounted on various substrates such as a circuit board using a joining member such as solder or a conductive adhesive. When mounting on a substrate, the bottom surface 4b of the element body 4 becomes the mounting surface, and the terminal electrodes 8 and the substrate are joined by the joining member.

[0019] The element body 4 has a coil portion 5 inside. This coil portion 5 is formed by winding a wire 6 as a conductor in a coil shape. In FIG. 1 of the present embodiment, the coil portion 5 is an air-core coil wound in a general normal winding, but the winding method of the wire 6 is not limited to this. For example, it may be an air-core coil in which the wire 6 is wound in an α-winding, a flat winding, or an edgewise winding.

[0020] The wire 6 is mainly composed of a conductor portion containing a low-resistance metal such as copper and an insulating coating covering the outer periphery of the conductor portion. More specifically, the conductor portion is composed of pure copper such as oxygen-free copper or tough pitch copper, an alloy containing copper such as phosphor bronze, brass, red copper, beryllium copper, silver-copper alloy, or a copper-coated steel wire.

[0021] The insulating coating only needs to have electrical insulation and is not particularly limited. For example, epoxy resin, acrylic resin, polyurethane, polyimide, polyamideimide, polyester, nylon, polyester, or a synthetic resin obtained by mixing at least two of the above resins is exemplified.

[0022] Furthermore, in this embodiment, the wire 6 constituting the coil portion 5 is a round wire, as shown in Figure 1, and the cross-sectional shape of the conductor portion is circular. However, it is not limited to a round wire; a flat wire or the like may also be used. The pair of lead portions 6a at both ends of the wire 6 are each exposed from the coil portion 5 to the outer surface (for example, the bottom surface 4b) of the element body 4 and connected to the terminal electrodes 8, 8, respectively. Both lead portions 6a are made of wire 6, but at the portion exposed to the bottom surface 4b, the insulating coating on the outer circumference of the wire 6 is removed, exposing the conductor portion of the wire 6.

[0023] In this embodiment, the terminal electrode 8 may have a resin electrode layer. Alternatively, the terminal electrode 8 may have a laminated structure comprising a resin electrode layer and other electrode layers. When the terminal electrode 8 has a laminated structure, the resin electrode layer is located in the portion that contacts the bottom surface 4b of the element body 4, and the other electrode layers may be a single layer or multiple layers, and their material is not particularly limited.

[0024] For example, the other electrode layers can be made of metals such as Sn, Au, Cu, Ni, Pt, Ag, and Pd, or alloys containing at least one of these metal elements, and can be formed by plating or sputtering. Furthermore, the overall thickness of the terminal electrode 8 is preferably 3 μm to 60 μm on average, and the thickness of the resin electrode layer is preferably 1 μm to 50 μm.

[0025] The resin electrode layer of the terminal electrode 8 contains a resin component and a conductive powder. The resin component in the resin electrode layer is composed of a thermosetting resin such as epoxy resin or phenolic resin. On the other hand, the conductive powder can be composed of metal powders such as Ag, Au, Pd, Pt, Ni, Cu, Sn, or metal powders of alloys containing at least one of the above, and it is particularly preferable that it contains Ag as the main component.

[0026] Furthermore, the shape of the conductive powder can be close to a sphere, elongated spherical, irregular block-like, needle-like, or flattened, with needle-like or flattened shapes being particularly preferred. In this embodiment, flattened particles refer to particles with an aspect ratio (ratio of the length in the longitudinal direction to the length in the short direction) of 2 to 30 in the cross-section of the resin electrode layer. The average particle size of the conductive powder can be measured by observing the cross-section of the resin electrode layer with SEM or STEM and performing image analysis on the resulting cross-sectional photograph. In this measurement, the average particle size of the conductive powder is calculated based on the maximum length.

[0027] In this embodiment, the element body 4 is made of, for example, a compacted magnetic core, and is formed by press-molding a compacted magnetic core precursor containing the granules 10 shown in Figure 2 together with an air-core coil of wire 6. The granules 10 are made of a composite magnetic material composition, which has a binder 14 and a plurality of magnetic particles 12 bound together by the binder 14. The binder 14 will be described later.

[0028] The magnetic particles 12 can be any magnetic material and are not particularly limited, but metallic magnetic particles are preferred. Examples include pure iron, Fe-Ni alloys, Fe-Si alloys, Fe-Co alloys, Fe-Si-Cr alloys, Fe-Si-Al alloys, amorphous metals, Fe-containing nanocrystalline alloys, other soft magnetic alloys, or combinations thereof. The magnetic particles 12 may also contain additional components as appropriate.

[0029] The magnetic particles 12 contained within the element body 4 can have a median diameter (D50) of approximately 0.1 μm to 100 μm. Furthermore, the magnetic particles 12 may be composed of a mixture of large particles with a D50 of 10 μm to 50 μm, medium particles with a D50 of 1 μm to 9 μm, and small particles with a D50 of 0.3 μm to 0.9 μm. In addition to the above combinations of the three particle groups, combinations of large and medium particles, large and small particles, and medium and small particles are also permitted. The large, medium, and small particles may all be made of the same material, or they may be made of different materials.

[0030] As described above, when mixing multiple particle groups, the proportion of each particle group is not particularly limited. For example, when mixing three types of particle groups (large particles, medium particles, and small particles), if the total area occupied by the large, medium, and small particles in the cross-section of the element body 4 is taken as 100%, it is preferable that the area occupied by the large particles be 5% to 30%, the area occupied by the medium particles be 0% to 30%, and the area occupied by the small particles be 50% to 90%. By composing the magnetic particles 12 with multiple particle groups, the packing density of the magnetic particles 12 contained in the element body 4 can be increased. As a result, various characteristics of the inductor 2, such as permeability, eddy current loss, and DC superposition characteristics, are improved.

[0031] The particle size of the magnetic particles 12 and the area occupied by each particle group can be measured by observing a cross-section of the element body 4 using a scanning electron microscope (SEM) or scanning transmission electron microscope (STEM), and then performing image analysis of the resulting cross-sectional image using software. In this case, it is preferable to measure the particle size of the magnetic particles 12 in terms of equivalent circle diameter.

[0032] Preferably, the magnetic particles 12 are nearly spherical. However, the magnetic particles 12 may include irregularly shaped magnetic particles 12 along with spherical magnetic particles 12.

[0033] Spherical shape refers to a shape where the average circularity is defined as 0.9 or greater, based on the cumulative circularity distribution of magnetic particles 12 observed on the fracture surface of the compacted magnetic core 4, with 50% of the distribution being the average circularity. Here, circularity is calculated using known methods such as image analysis of the cross-section.

[0034] Furthermore, the magnetic particles 12 of the metal contained in the element body 4 may be insulated from each other. One method of insulation is to form an insulating film on the particle surface. Examples of insulating films include films formed from resin or inorganic materials, and oxide films formed by oxidizing the particle surface by heat treatment. When forming an insulating film from resin or inorganic materials, examples of resins include silicone resin and epoxy resin.

[0035] Examples of inorganic materials include phosphates such as magnesium phosphate, calcium phosphate, zinc phosphate, and manganese phosphate; silicates such as sodium silicate (water glass); soda-lime glass; borosilicate glass; lead glass; aluminosilicate glass; borate glass; and sulfate glass. The thickness of the insulating film on the magnetic particles 12 is preferably 5 nm to 200 nm. Forming an insulating film improves the insulation between particles, thereby improving the dielectric strength of the inductor 2.

[0036] Next, we will explain how to manufacture the element body 4. First, a powder core precursor, which will be the raw material for the powder core that constitutes the element body 4 shown in Figure 1, is prepared. The powder core precursor contains granules 10 shown in Figure 2 and, if necessary, other additives. Examples of additives include molding lubricants and fluidity imparters. Examples of molding lubricants include zinc stearate, lithium stearate, strontium stearate, barium stearate, and magnesium stearate. Examples of fluidity imparters include fine particle silica, fumed silica, and colloidal silica.

[0037] The granules 10 shown in Figure 2 are obtained by kneading a soft magnetic powder containing, for example, magnetic particles 12 of a metal with an insulating coating, with a binder diluted in a solvent, and then drying the mixture. The resulting granules may be sized using, for example, a sieve with a mesh size of 100 to 400 μm.

[0038] When preparing the granules 10, ketones such as acetone or ethanol can be used as the solvent to dilute the binder. In this embodiment, a specific epoxy resin, described later, is used as the binder 14. There are no particular restrictions on the content of the binder 14, but for example, if the magnetic particles 12 are 100 parts by weight, it is preferable to use 2 to 5 parts by weight. By kneading the binder in this ratio, the volume packing ratio of magnetic particles 12 in the resulting element body 4 (excluding the wire 6) will be approximately 70 to 90 vol%. The resin of the binder 14 contained in the granules 10 may be in an uncured state, for example, uncured or semi-cured.

[0039] The granules 10 are filled into a mold together with an air-core coil (coil portion 5) as an insert member, and compression molding is performed. This yields a molded body having the shape of an element body 4. By appropriately heat-treating this molded body, the resin of the binder 14 hardens, and an element body 4 made of compacted magnetic core is obtained. The heat treatment conditions can be appropriately determined according to the type of binder 14 used. The element body 4 thus obtained, made of compacted magnetic core, has a coil portion 5 embedded inside, and by applying a voltage to the coil portion 5, it functions as an inductor 2.

[0040] In this embodiment, the binder 14 contained in the granules 10 shown in Figure 2 mainly contains an epoxy resin having a bisphenol-type skeleton with suppressed molecular rotation as shown in the following chemical formula (1). Preferably, the epoxy resin shown in the following chemical formula (1) is contained in the binder 14 at a concentration of at least 20% by mass based on 100% by mass of the total amount of the binder 14, but other resins may also be included. Examples of other resins include curing agents that readily form oriented structures with the specific epoxy resins shown below, and curing accelerators. Examples of curing agents include curing agents having a naphthalene skeleton and curing agents having a biphenyl skeleton. Imidazole resins and the like are used as curing accelerators.

[0041] [ka]

[0042] In the above chemical formula (1), each R represents a hydrogen atom, a C1-C6 alkyl group, or a C1-C6 alkoxy group, or a combination thereof, and p and q are integers of 0 or more. That is, at least one of the R in chemical formula (1) may be omitted. Furthermore, X in chemical formula (1) has a cyclic structure as shown in (2) or (3) below, and is preferably condensed with ring A or ring B described later.

[0043] [ka]

[0044] In chemical formula (2), Y is O, NH, or NR. 1 , CR 1 R 2 , SiR 1 R 2 The above R is one of the following, where Z is one of a carbonyl group, a methylene group, or an ester group, and n is a non-negative integer. 1 and R 2 These represent a hydrogen atom, a methyl group, an aromatic ring, and an imide ring, respectively. In chemical formula (2), * indicates a bonding site.

[0045] [ka]

[0046] In chemical formula (3), n is a non-negative integer, and * indicates a bonding site.

[0047] Rings A and B each represent aromatic rings, which may have substituents. The aromatic rings represented by rings A and B may be carbon rings with carbon atoms as ring constituent atoms, or hetero rings having carbon atoms in addition to heteroatoms such as oxygen atoms, nitrogen atoms, and sulfur atoms, but are preferably carbon rings. The aromatic rings represented by rings A and B are preferably 3 to 10-membered aromatic rings. The aromatic rings represented by rings A and B include not only monocyclic aromatic rings and fused rings formed by the fusion of two or more monocyclic aromatic rings, but also fused rings formed by the fusion of one or more monocyclic aromatic rings with one or more monocyclic non-aromatic rings.

[0048] Suitable specific examples of the carbon rings represented by rings A and B include benzene rings, indene rings, naphthalene rings, azulene rings, heptalene rings, biphenylene rings, as-indacene rings, s-indacene rings, acenaphthylene rings, fluorene rings, phenalene rings, phenanthrene rings, anthracene rings, fluorantene rings, acephenanthrene rings, aceanthrene rings, triphenylene rings, pyrene rings, chrysene rings, tetracene rings, pleiaden rings, picene rings, perylene rings, pentaphene rings, pentacene rings, tetraphenylene rings, and hexaphene rings.

[0049] More preferably, the rings include a benzene ring, a naphthalene ring, a phenanthrene ring, anthracene ring, a triphenylene ring, a pyrene ring, a chrysene ring, a tetracene ring, a picene ring, a pentacene ring, and even more preferably, a benzene ring.

[0050] Suitable examples of heterocycles represented by ring A and ring B include pyridine rings, pyridazine rings, pyrimidine rings, pyrrole rings, furan rings, benzofuran rings, imidazole rings, thiophene rings, thiazole rings, fused rings formed by the fusion of these with one or more of the aforementioned aromatic rings, and fused rings formed by the fusion of these with one or more non-aromatic rings.

[0051] The epoxy resins specified above may be used individually, satisfying these structural requirements, or in combination of two or more types. Preferably, the epoxy resins specified above have a conjugated structure with multiple aromatic rings. Preferably, the multiple aromatic rings have a conjugated structure with imide structures. Alternatively, it is also preferable that the epoxy resins specified above have an amide structure within the molecule.

[0052] By forming a compacted molded body (element body 4) using granules 10 having a binder 14 containing a specific epoxy resin and magnetic particles 12 according to this embodiment, adhesion to the cavity surface of the mold and damage to the molded body can be prevented. Furthermore, the glass transition temperature (Tg) of the resulting element body 4 can be increased, improving the heat resistance of the inductor element 2. The glass transition temperature of the element body 4 containing the specific epoxy resin (after curing) described above can be measured, for example, by DSC (differential heat capacity analysis), and can preferably be raised to 170°C or higher.

[0053] Furthermore, in this embodiment, it is possible to suppress the degradation of the characteristics of the element body 4 in high-temperature environments, thereby realizing an inductor 2 with excellent reliability. Examples of suppressing the degradation of the characteristics of the element body 4 in high-temperature environments include suppressing changes in the magnetic permeability of the element body 4 and suppressing the rate of change in the weight of the element body 4. In addition, the withstand voltage of the element body 4 is also improved. In particular, in fields such as automotive where high reliability is required, a higher withstand voltage is preferable.

[0054] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways within the scope of the present invention.

[0055] For example, the magnetic particles 12 may be not only metal (including alloy) magnetic particles, but also ferrite particles or other non-metallic materials.

[0056] Furthermore, examples of electronic components are not limited to coil components such as inductors 2 having an element body 4 made of a compacted magnetic core with a built-in coil section 5, but also include coil components in which a wire 6 is wound around a compacted magnetic core that does not have a built-in coil section. In addition, electronic components that can be manufactured using the granules 10 of the above-described embodiment are not limited to inductors, but may also include magnetic shielding components that use magnetic materials other than magnetic cores, such as reactors, transformers, and contactless power supply devices. [Examples]

[0057] The present invention will be described below based on more detailed examples, but the present invention is not limited to these examples.

[0058] Example 1 First, as shown in Figure 2, a powdered magnetic core precursor was prepared containing granules 10 having magnetic particles 12 and a binder 14. As the binder 14, a molecular rotation-suppressed bisphenol-type epoxy resin, as shown in the following chemical formulas (4) and (5), which are further concretizations of the aforementioned chemical formulas (1) and (2), was used.

[0059] Specifically, a paint was prepared by dissolving 100 parts by mass of epoxy resin, 50 parts by mass of biphenylarachyl-type phenolic resin as a curing agent, and 1 part by mass of 2-ethyl-4-methylimidazole as a curing accelerator in a solvent consisting of acetone.

[0060] [ka]

[0061] [ka]

[0062] Next, the prepared paint was mixed with magnetic particles 12, kneaded using a kneader, and dried to produce a compacted magnetic core precursor consisting of granules 10. As the magnetic particles 12, a mixed metal powder was used containing 75% by mass of Fe-Si-Cr-BC amorphous metal powder with a D50 of 25 μm and 25% by mass of pure Fe powder with a D50 of 4 μm.

[0063] The amount of binder was adjusted so that there were 3 parts by mass of binder per 100 parts by mass of mixed metal powder. Next, using a mold, the granules 10 were compression molded under conditions of a mold temperature of 120°C and a molding pressure of 400 MPa to form a toroidal shape with an outer diameter of 18 mm and an inner diameter of 10 mm. Finally, the obtained molded product was heat-cured at 180°C for 1 hour to prepare a sample of a toroidal powder magnetic core (a magnetic component without a built-in coil). The following measurements were performed on the obtained powder magnetic core sample.

[0064] <Core weight change rate> Samples of compacted magnetic cores were left at 180°C for 660 hours, and the weight change rate before and after the period was determined. The results are shown in Table 1. A weight change rate closer to 0 is preferable.

[0065] <Relative permeability> A closed magnetic circuit was formed by winding a powder core sample, and the relative permeability μ was measured at a frequency of 100 kHz and 50 mV using an LCR meter. The results are shown in Table 1.

[0066] <μ change rate> Samples of compacted magnetic cores were left at 180°C for 1100 hours, and the percentage change in relative permeability μ before and after the period was determined. The results are shown in Table 1. A percentage change closer to 0 is preferable.

[0067] <Glass transition temperature Tg> A sample of compacted magnetic core was ground into a powder using a mortar and pestle, and the glass transition temperature (Tg) of the powder was measured using a differential scanning heat capacity analyzer at a heating rate of 5°C / min. The results are shown in Table 1. A glass transition temperature of 170°C or higher is preferable.

[0068] <Withstand voltage> A pair of In-Ga electrodes were formed on a toroidal powder core sample. A voltage was applied, and the voltage when a 100mA current flowed was measured. The withstand voltage (V) was measured by dividing this voltage by the thickness of the powder core in the direction in which it was sandwiched by the electrodes. The results are shown in Table 1. A higher withstand voltage is preferable.

[0069] <Moldability> The moldability was evaluated by observing whether the molded body adhered to the mold when it was removed from the mold after heat press molding, and by checking for any fractures or other damage to the molded body. For 100 molded body samples, a rating of G was given if neither adhesion to the mold nor fracture was observed. A rating of B was given if at least one out of ten samples showed adhesion to the mold or fracture, and a rating of VB was given if at least one out of ten samples showed both adhesion to the mold and fracture. The results are shown in Table 1. A higher withstand voltage is preferable.

[0070] <Degradation level of binder resin alone> Instead of using powdered magnetic core samples, a binder resin, hardener, and curing accelerator were dissolved in a solvent, poured into a mold, molded, the solvent in the molded product was dried, and then heat-cured to produce test pieces of the specified size.

[0071] Samples of molded bodies containing only the binder resin were left at a temperature of 180°C for 2400 hours, and the degree of decomposition was examined at predetermined intervals. The results are shown in the plotted black circles in Figure 3. In the graph in Figure 3, the horizontal axis represents the standing time, and the vertical axis represents the degree of decomposition (%). The degree of decomposition was measured by weight loss using an electronic balance.

[0072] Comparative Example 1 Samples of compacted magnetic cores were prepared in the same manner as in Example 1, except that an orthocresol novolac type epoxy resin was used as the binder and a phenol novolac resin was used as the curing agent, and the same evaluation as in Example 1 was performed. The results are shown in Table 1. In addition, the degree of decomposition of the binder resin used in Comparative Example 1 was measured in the same manner as in Example 1, and the results are shown in the plots marked with × in Figure 3.

[0073] Comparative Example 2 Except for using a mixture of orthocresol novolac epoxy resin and maleimide-modified epoxy resin as the binder and phenol novolac resin as the curing agent, compacted magnetic core samples were prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0074] Comparative Example 3 Samples of compacted magnetic cores were prepared in the same manner as in Example 1, except that a diphenyl ether type epoxy resin was used as the binder and a phenol novolac resin was used as the curing agent. The same evaluation as in Example 1 was performed. The results are shown in Table 1.

[0075] Comparative Example 4 Except for using a naphthalene-type epoxy resin as the binder and a naphthalene-type curing agent as the curing agent, a sample of compacted magnetic core was prepared in the same manner as in Example 1, and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0076] Comparative Example 5 Samples of compacted magnetic cores were prepared in the same manner as in Example 1, except that a biphenylene-type epoxy resin was used as the binder and a biphenylaralkyl-type phenolic resin was used as the curing agent, and the same evaluation was performed as in Example 1. The results are shown in Table 1. In addition, the degree of decomposition of the binder resin alone used in Comparative Example 5 was measured in the same manner as in Example 1, and the results are shown in the triangular plots in Figure 3.

[0077] Comparative Example 6 Samples of compacted magnetic cores were prepared in the same manner as in Example 1, except that a polyfunctional epoxy resin was used as the binder and a polyfunctional phenolic resin was used as the curing agent, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

[0078] Example 2 Except for using metal powder from one of the following as the magnetic particles 12, an Fe-Ni alloy, Fe-Si alloy, Fe-Co alloy, Fe-Si-Cr alloy, or Fe-Si-Al alloy, instead of an amorphous metal powder with an Fe-Si-Cr-BC composition, an evaluation was performed in the same manner as in Example 1, and it was confirmed that the same results as in Example 1 could be obtained.

[0079] Example 3 Except for using 100% by mass of Fe-Si-Cr-BC amorphous metal powder with a D50 of 25 μm as the magnetic particle 12, the same evaluation as in Example 1 was performed, and it was confirmed that the same results as in Example 1 could be obtained.

[0080] evaluation As shown in Table 1, Example 1, which used a bisphenol-type epoxy resin having a structure in which a predetermined molecular rotation was suppressed, showed less weight change and less deterioration of magnetic properties even when exposed to high temperatures for a long time, compared to Comparative Examples 1 to 6. Furthermore, Example 1 was confirmed to have a high Tg of 170°C or higher, a high withstand voltage of 300V or higher, and good moldability. In contrast, Comparative Examples 1 to 6 were unable to satisfy all of these properties simultaneously.

[0081] As shown in Figure 3, there is no significant difference in the rate of decomposition of the molecular rotation-inhibiting resin used in Example 1 over time in a high-temperature environment compared to the rate of decomposition of the novolac-type resin used in Comparative Example 1 or the biphenyl-type resin used in Comparative Example 5, when considering the resin alone. However, as shown in Table 1, the powdered magnetic core sample from Example 1 yielded superior results compared to the powdered magnetic core samples from Comparative Examples 1 to 6. It is thought that the metallic magnetic particles exert some kind of negative catalytic effect with the molecular rotation-inhibiting resin, resulting in effects that would not be possible with the resin alone.

[0082] [Table 1] [Explanation of symbols]

[0083] 2… Inductor 4… Element body (pressed magnetic core) 4a…Top surface 4b…Bottom surface 4c,4d… End face 5… Coil section 6… Wire 6a… Lead section 8…Terminal electrode 10... Granules (composite magnetic composition) 12…magnetic particles 14… Binder

Claims

1. A composite magnetic composition comprising a binder containing a bisphenol-type epoxy resin with suppressed molecular rotation, and a plurality of magnetic particles bound together by the binder, The bisphenol-type epoxy resin with suppressed molecular rotation has the structure shown in the following chemical formula, and is a composite magnetic material composition. 【Chemistry 1】 【Chemistry 2】

2. The composite magnetic composition according to claim 1, wherein the magnetic particles are metallic magnetic particles.

3. The composite magnetic composition according to claim 2, wherein the metallic magnetic particles have at least an amorphous metal.

4. The composite magnetic composition according to claim 2 or 3, wherein the metallic magnetic particles have at least pure Fe.

5. The composite magnetic composition according to any one of claims 1 to 4, wherein the magnetic particles are spherical.

6. A magnetic member having the composite magnetic composition according to any one of claims 1 to 5.

7. An electronic component having the magnetic member described in Claim 6.

8. The electronic component according to claim 7, wherein the magnetic member is a compacted magnetic core.

9. The electronic component according to claim 8, having a coil inside the powdered magnetic core.

Images