Manufacturing method for coil components using composite magnetic material

Abstract

To provide a manufacturing method of a coil component in which a dielectric breakdown voltage is less likely to decrease when a DC voltage is applied.SOLUTION: A manufacturing method of a coil component includes a compression molding step of preparing a mold having one or more discharge holes having a hole diameter through which the metal magnetic powder can pass and having a total opening area of 0.003% or more and 1.5% or less of a surface area of the coil component in a state in which an upper die and a lower die are brought into contact with each other by arranging a lead-out portion of a coil in a wiring groove 33 having the upper die 11 and the lower die 21 and having the lead-out portion 103 of the coil arranged in a region to be brought into contact with the lower die of the upper die or in a region to be brought into contact with the upper die of the lower die, arranging a winding portion of the coil inside the mold, causing the lead-out portion placed in the wiring groove to protrude from the inside of the mold, filling the inside of the mold with a composite magnetic material, heating the mold, and discharging the composite magnetic material from the discharge holes, and performing compression molding to obtain a composite magnetic molded body, and a thermosetting step of obtaining the coil component by heat-treating and thermosetting the composite magnetic molded body.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a coil component using a composite magnetic material. [Background technology]

[0002] There are various types of coil parts used in electronic devices, etc., but the most widely used coil parts are obtained by integrally molding a composite magnetic material in which metal magnetic powder is dispersed in a thermosetting resin (binder resin) and a coil or a coil assembly. For example, Patent Document 1 describes a coil part in which a wound coil is enclosed in a powder magnetic body made of a mixture containing soft magnetic powder and a binder, and is molded at 4.5 to 10.0 ton / cm in a mold. 2 The document describes an inductance component (coil component) that is integrated by pressure molding under a molding pressure of 1000 MPa. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-319020 A Summary of the Invention [Problem to be solved by the invention]

[0004] When such a composite magnetic material is used to manufacture a coil component containing a coil by compression molding using a mold, the wiring groove of the upper or lower mold of the mold in which the lead-out part of the coil (the wire that becomes the coil lead-out line of the coil component) is arranged is usually designed so that the clearance between this coil lead-out part and the wiring groove of the upper or lower mold is extremely small. Furthermore, this mold is designed so that there is almost no clearance in other parts during molding. When using such a mold to perform thermal molding of a composite magnetic material with an embedded coil (heating the mold to perform compression molding), if further pressure is applied after the composite magnetic material is sufficiently filled in the mold, the clearance between the lead-out part of the coil and the wiring groove is large enough that most of the metal magnetic powder contained in the composite magnetic material cannot pass through, so that the thermosetting resin in the composite magnetic material separates and flows into this clearance and is discharged, which may result in a decrease in the content of thermosetting resin in the obtained molded body (coil component).

[0005] And, because the content of the resin component that insulates the metal magnetic powder, which is an electrical conductor, in the obtained molded body (coil component) is reduced, the insulating layer of the resin component between the metal magnetic powder becomes extremely thin, and the metal magnetic powder comes into electrical contact with each other, which causes a problem that the dielectric breakdown voltage when a direct current voltage is applied becomes low (for example, 50 V / mm or less).In particular, when a composite magnetic material containing a thermosetting resin with a low melt viscosity is used, the metal magnetic powder and the thermosetting resin are easily separated during thermal molding, and the above problem tends to occur more easily.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a manufacturing method for a coil component in which separation of the metal magnetic powder and thermosetting resin in the composite magnetic material in which the coil is embedded is unlikely to occur during thermal molding, and in which the breakdown voltage of the obtained coil component is unlikely to decrease when a DC voltage is applied to it. [Means for solving the problem]

[0007] In order to solve the above problems, the inventors conducted intensive research and discovered that by performing thermal molding using a mold having a discharge hole with a specified hole diameter and opening area, separation of the metal magnetic powder and the thermosetting resin in the composite magnetic material in which the coil is embedded during this thermal molding is unlikely to occur, and the dielectric breakdown voltage of the resulting coil component when a DC voltage is applied is unlikely to decrease, thereby completing the present invention.

[0008] That is, the present invention is a manufacturing method for a coil component in which a composite magnetic thermosetting molded body obtained by molding and heat-curing a composite magnetic material composed of a metal magnetic powder and a thermosetting resin has a wound portion of a coil enclosed therein, and a lead-out portion of this coil protrudes from the composite magnetic thermosetting molded body, the manufacturing method being provided with an upper mold and a lower mold, and a wiring groove for arranging the lead-out portion of the coil in an area of ​​the upper mold that comes into contact with the lower mold or an area of ​​the lower mold that comes into contact with the upper mold, and further, in a state in which the lead-out portion of the coil is arranged in this wiring groove and the upper mold and the lower mold are brought into contact with each other, the hole diameter is such that the metal magnetic powder can pass through and the total opening area is greater than the coil portion the composite magnetic material is compressed and molded while being discharged from the discharge holes to obtain a composite magnetic molded body containing the coil winding portion; and a heat curing process in which the composite magnetic material is heat-treated to heat-cur it, thereby obtaining a coil component. Effect of the Invention

[0009] According to the present invention, a manufacturing method for coil components can be provided in which separation of the metal magnetic powder and thermosetting resin in the composite magnetic material in which the coil is embedded is unlikely to occur during thermal molding, and the breakdown voltage of the resulting coil component is unlikely to decrease when a DC voltage is applied to it. [Brief description of the drawings]

[0010] [Figure 1]1 is a perspective view of a state in which a coil is placed inside a lower die of a mold used in a manufacturing method of a coil component according to this embodiment, and a lead-out portion of the coil is placed in a wiring groove. FIG. [Diagram 2] 2 is a perspective view of the lower and upper dies of the mold shown in FIG. 1 in contact with each other. FIG. [Diagram 3] 13 is an enlarged perspective view of the vicinity of the wiring groove in a state in which a lead-out portion of a coil is disposed in the wiring groove of a modified example of a mold used in the manufacturing method of a coil component according to the present embodiment. FIG. [Figure 4] 1 is a perspective view of a state in which a coil is placed inside a lower die of a mold used in a conventional method for manufacturing a coil component, and a lead-out portion of the coil is placed in a wiring groove. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described.

[0012] In the method for manufacturing a coil component according to this embodiment, a coil component is manufactured using a composite magnetic material made of a metal magnetic powder and a thermosetting resin, and a coil having a winding portion and an extraction portion. First, each material will be described.

[0013] <Composite magnetic material> The composite magnetic material used in the manufacturing method of the coil component according to the present embodiment is a material composed of a metal magnetic powder and a thermosetting resin, that is, a material that contains at least a metal magnetic powder and a thermosetting resin, and these are the main components (a total of 90 wt% or more). Note that composite magnetic materials containing other components (for example, dispersants, plasticizers, lubricants, etc.) besides the above are not excluded as long as they do not affect the effects of the present invention.

[0014] The content of the metal magnetic powder in the composite magnetic material is preferably 95 wt% or more, and more preferably 96 wt% or more. The upper limit is preferably 98.5 wt% or less, and more preferably 98 wt% or less. The content of the thermosetting resin is preferably 1.5 wt% or more, and more preferably 2.0 wt% or more. The upper limit is preferably 5.0 wt% or less, and more preferably 4.0 wt% or less. Furthermore, from the viewpoint of ease of filling into a mold, this composite magnetic material is preferably a granulated powder. The metallic magnetic powder and the thermosetting resin that constitute this composite magnetic material will be described in detail below.

[0015] (Metal magnetic powder) The metal magnetic powder is a magnetic powder that can be obtained by a method of powdering a metal magnetic material, and contains iron as a main component. For example, iron and alloys containing iron (iron-silicon, iron-aluminum-silicon alloy, iron-nickel alloy, etc.) can be used as the metal magnetic material. However, these are merely examples, and other metal magnetic materials may be used. In addition, the metal magnetic powder may be a powder of one type of metal magnetic material, or a powder of two or more types of metal magnetic materials mixed together.

[0016] In particular, from the viewpoint of magnetic properties and availability, it is more preferable to use a metal magnetic powder containing iron as a main component and chromium (Cr), silicon (Si), nickel (Ni), aluminum (Al), cobalt (Co), carbon (C), boron (B), etc. as sub-components. Also, amorphous metal powder or pure iron powder may be used. Specifically, alloy powders such as Fe-Ni (permalloy), Fe-Si (silicon steel), Fe-Al, Fe-Co (permendur), Fe-Si-Cr, Fe-Al-Cr, and Fe-Si-Al (sendust), non-crystalline metal powders such as Fe-Si-Cr-B amorphous powders, and crystalline iron powders such as carbonyl iron powders, etc., may be used. Among the above materials, it is more preferable to use a material that can be made into a substantially spherical metal magnetic powder (for example, Fe-Si-Cr-B amorphous powder or Fe-Si-Cr alloy powder). This is because it becomes easier to compress and mold the composite magnetic material containing this metal magnetic powder.

[0017] The content of iron, which is the main component of the metal magnetic powder, is preferably 85 wt% or more, more preferably 86 wt% or more, and is preferably 98 wt% or less, more preferably 97 wt% or less. It is preferable that the powder contains one or more of the above-mentioned minor components, with the remainder being iron and unavoidable impurities.

[0018] Furthermore, the chromium content of this metal magnetic powder is preferably 2 wt % or more and 10 wt % or less, and more preferably 2.5 wt % or more and 8 wt % or less. Chromium easily combines with oxygen in the air to produce a chemically stable oxide (e.g., Cr2O3, etc.). Therefore, a composite magnetic thermosetting molded body containing chromium has particularly excellent corrosion resistance. Furthermore, since chromium oxide has a high specific resistance, a chromium oxide layer is formed near the surface of the particles constituting the composite magnetic thermosetting molded body of the coil component obtained by the manufacturing method of the coil component according to this embodiment, which makes it easier to insulate between the particles. Therefore, by setting the chromium content within the above range, it is possible to obtain a metal magnetic powder that can constitute a composite magnetic material that has excellent corrosion resistance and can be used to manufacture coil components with smaller eddy current loss.

[0019] For the same reason, the metal magnetic powder preferably has a nickel content of 2 wt% to 10 wt%, more preferably 2.5 wt% to 8 wt%, and similarly, the metal magnetic powder preferably has an aluminum content of 2 wt% to 10 wt%, more preferably 2.5 wt% to 8 wt%.

[0020] Furthermore, the silicon content of this metal magnetic powder is preferably 2 wt % or more and 10 wt % or less, and more preferably 3 wt % or more and 8 wt % or less. Silicon is a component that can increase the relative magnetic permeability of the coil component obtained. Silicon is also a component that can suppress interparticle eddy current loss because the resistivity of the metal magnetic powder increases when the metal magnetic powder contains silicon. Therefore, by setting the silicon content within the above range, a metal magnetic powder that can constitute a composite magnetic material that can produce coil components with high relative magnetic permeability and low eddy current loss can be obtained.

[0021] The metallic magnetic powder may contain at least one component selected from the group consisting of boron (B), titanium (Ti), vanadium (V), manganese (Mn), copper (Cu), gallium (Ga), germanium (Ge), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), and tantalum (Ta) as a component with a lower content than the above components. In this case, the total content of these components is preferably 5wt% or less. Furthermore, it may contain components such as phosphorus (P) and sulfur (S) that are inevitably mixed in during the manufacturing process, but in that case, the total content of these components is preferably 1 wt % or less.

[0022] The average particle diameter of this metal magnetic powder (D 50) is preferably 2 μm or more and 40 μm or less, and more preferably 4 μm or more and 30 μm or less. Furthermore, the particle shape of the metal magnetic powder is preferably approximately spherical (for example, an approximately spherical shape in which the value obtained by dividing the major axis by the minor axis is 2 or less, or even 1.5 or less), because this makes it easier to compress and mold a composite magnetic material containing this metal magnetic powder.

[0023] The maximum particle size of this metal magnetic powder is preferably 75 μm or less, more preferably 70 μm or less, even more preferably 60 μm or less, and even more preferably 50 μm or less.

[0024] Here, the above-mentioned "average particle diameter (D 50 "Maximum particle size" and "median size" refer to the powder diameter at 50% cumulative value in the volumetric particle size distribution (median diameter) and the maximum particle diameter, respectively, determined using a particle size distribution analyzer by the laser diffraction / scattering method (Microtrack method). In the case where the particles are aggregated, the particle size of the aggregate is referred to. A specific example of the measuring device is the laser diffraction / scattering particle size distribution analyzer (particle size distribution) LA-960 (manufactured by HORIBA Seisakusho).

[0025] In addition, it is preferable to use, as the metallic magnetic powder, a metallic magnetic material powdered by water atomization or gas atomization. Here, the "water atomization method" refers to a method for producing metal powder by colliding molten metal with water (atomized water) sprayed at high speed to pulverize the molten metal and cool it. The "gas atomization method" is a method in which a jet stream of inert gas or air is blown onto a flow of molten metal from the surrounding area to pulverize the flow of molten metal, solidify it, and turn it into metal powder.

[0026] The metal magnetic powder produced by the water atomization method or the gas atomization method has a substantially spherical shape (close to a sphere), so that when a composite magnetic material containing this metal magnetic powder is used to produce a coil component, the filling rate can be easily increased. Also, as described above, the composite magnetic material containing this metal magnetic powder can be more easily compression molded.

[0027] Furthermore, the metal magnetic powder may be one that has been subjected to a drying process to remove water adsorbed on the powder surface, i.e., a metal magnetic dry powder obtained by drying the powder. Examples of the powder drying process include hot air treatment and dry heat treatment, and examples of drying conditions include treatment at a temperature of 100°C to 150°C for 30 minutes to 120 minutes.

[0028] In addition, the metal magnetic powder may be surface-treated with a silane-based or titanium-based coupling agent to improve wettability with a thermosetting resin, that is, a surface-treated metal magnetic powder obtained by surface-treating a powder with a silane-based or titanium-based coupling agent. As the silane-based or titanium-based coupling agent, it is more preferable to use a silane-based or titanium-based coupling agent having an epoxy group, an amino group, or an isocyanate group as a functional group, from the viewpoint of affinity with a thermosetting resin described later. As a surface treatment method for the powder, a dry treatment method in which a solution containing a coupling agent is dropped or sprayed while the powder is stirred with a mixer or the like, or a wet treatment method in which a solvent is added to the powder to make a slurry, a solution containing a coupling agent is added to the slurry, and the slurry is stirred, filtered, and dried, are exemplified. This surface treatment may be performed in combination with the drying treatment described above.

[0029] (thermosetting resin) The thermosetting resin is a reactive resin composition mainly composed of a prepolymer having a functional group, which is softened and flowed by heating, and gradually hardens by a crosslinking reaction that forms a three-dimensional network structure. The composite magnetic thermosetting molded body of the coil component obtained by the manufacturing method of the coil component according to the present embodiment contains a thermosetting resin composition, and in the present invention, this thermosetting resin composition may also be referred to as a "thermosetting resin". The thermosetting resin is not particularly limited as long as it plays a role as a binder resin and can be hardened by heating (for example, a resin used in a sealing material for semiconductors), and thermosetting epoxy resins (bisphenol type, naphthalene type, novolac type, aliphatic type, glycidylamine type, etc.), silicon resins (methylphenyl silicon resins, etc.), phenol resins (novolac type, resol type, etc.), polyamide resins, polyimide resins, melamine resins, polyphenylene sulfide resins, etc. may be used. A mixture of two or more types of thermosetting resins may also be used. In particular, from the viewpoint of heat resistance, it is more preferable to use an epoxy resin, and it is even more preferable to use a novolac type epoxy resin. In addition, the manufacturing method of the coil component according to this embodiment is characterized in that, by using a mold described later, separation of the metal magnetic powder and the thermosetting resin in the composite magnetic material is unlikely to occur during thermal molding, even when a composite magnetic material containing a thermosetting resin with a low melt viscosity is used.

[0030] Furthermore, from the viewpoint of ease of thermosetting, it is preferable that the thermosetting resin is mixed with a curing agent. As the curing agent, a phenol novolac type curing agent (phenol novolac resin, bisphenol A type novolac resin, etc.), a polyamide type curing agent (polyamide resin, etc.), an acid anhydride type curing agent such as maleic anhydride and phthalic anhydride, a latent amine type curing agent such as dicyandiamide and imidazole, an aromatic amine such as diaminodiphenylmethane and diaminodiphenylsulfone, etc. can be used. These curing agents can be used alone or in combination of two or more kinds. Furthermore, other additives such as a diluent, a filler, and a mold release agent may be mixed in the composition as long as they do not adversely affect the effects of the present invention.

[0031] In preparing the composite magnetic material, a solvent may be mixed with the thermosetting resin to make the thermosetting resin into a resin solution. This solvent is removed by drying or the like in each process described below, but from the viewpoint of ease of removal, it is preferable to use a small amount of solvent (for example, the ratio of the volume of the solvent to the total volume of the raw materials used in the composite magnetic material excluding the solvent is less than 5.0 vol%, and furthermore, 0.5 vol% to 2.0 vol%, etc.). The solvent is preferably one that can be removed by drying or the like in each process described below, and suitable examples include organic solvents such as alcohol, toluene, chloroform, methyl ethyl ketone, acetone, and ethyl acetate.

[0032] <Coil> The coil used in the manufacturing method of the coil component according to the present embodiment is formed by winding a wire such as a round wire or a flat wire. The shape, number, and number of turns of the wire are not particularly limited. The surface of the wire may be coated with an insulating material. The wire may be made of a metal material such as copper, and the diameter of the wire is not limited.

[0033] This coil includes a winding portion 101 around which the wire is wound, and a lead-out portion 103 from which the wire is led out from the winding portion. The lead-out portion 103 serves as a coil lead of the coil component. Furthermore, the winding portion 101 may have a core portion that serves as a magnetic core material. Alternatively, the winding portion 101 may be an air-core coil that does not have a core portion.

[0034] <Manufacturing method of coil parts> Next, each step of the method for manufacturing the coil component according to this embodiment using the above-mentioned materials will be described in detail.

[0035] The manufacturing method of the coil component according to the present embodiment includes at least a compression molding step and a heat curing step as described below. Note that, as long as the effect of the present invention is not affected, any other steps (e.g., a material preparation step, a polishing step after heat curing, etc.) may be included.

[0036] [Compression molding process] First, in this compression molding step, a predetermined mold is prepared. Specifically, a mold is prepared that includes an upper mold 11 and a lower mold 21, and has a wiring groove 33 along which the coil lead-out portion 103 can be arranged in the region of the upper mold 11 that contacts the lower mold 21, or in the region of the lower mold 21 that contacts the upper mold 11, and further has one or more discharge holes 35 that have a hole diameter that allows the metal magnetic powder to pass and a total opening area that is 0.003% to 1.5% of the surface area of ​​the coil component when the coil lead-out portion 103 is arranged in the wiring groove 33 and the upper mold 11 and the lower mold 21 are in contact with each other. This discharge hole 35 is capable of passing the metal magnetic powder in the composite magnetic material together with the thermosetting resin during thermal molding in which the mold is heated and compression molded, and the minimum hole diameter is, for example, the average particle diameter (D 50 ) may be 3 to 70 times, further 5 to 50 times, or further 5 to 20 times. In addition, by having the total opening area of ​​the discharge holes 35 as described above, the outflow amount of the composite magnetic material during thermal molding is prevented from becoming excessively large.

[0037] In particular, it is preferable that the minimum hole diameter of the discharge hole 35 of this mold is equal to or larger than the maximum particle diameter of the metal magnetic powder. Furthermore, it is even more preferable that the minimum hole diameter is larger than the maximum particle diameter of the metal magnetic powder. This is because it is easier to pass the composite magnetic material through the discharge hole 35 in a homogeneous state during thermal molding.

[0038] Here, the "hole diameter" of the discharge hole 35 refers to the diameter of the maximum inscribed circle in a cross section perpendicular to the hole of the discharge hole 35 (a cross section perpendicular to the penetrating direction of the discharge hole 35). Also, the "minimum hole diameter" of the discharge hole 35 refers to the smallest diameter among the diameters of the maximum inscribed circles in all cross sections perpendicular to the hole of the discharge hole 35. Therefore, when the minimum hole diameter of the discharge hole 35 is equal to or larger than the maximum particle diameter of the metal magnetic powder, all of the metal magnetic powder contained in the composite magnetic material can pass through together with the thermosetting resin. The opening area of ​​the discharge hole 35 is the area of ​​the opening of the discharge hole 35 on the side of the internal space of the mold, and the "total opening area" is the sum of these opening areas (the opening area of ​​the discharge hole 35 when there is only one discharge hole 35). Furthermore, the "surface area of ​​the coil component" is the surface area of ​​the composite magnetic thermoset molded body obtained after the compression molding process and the thermosetting process (the same as the surface area of ​​the internal space of the mold in a sufficiently compressed state), and does not include the surface area of ​​the lead-out portion 103 of the coil (the surface area of ​​the wire line).

[0039] The lower limit of the total opening area of ​​the discharge holes 35 is more preferably 0.005% or more of the surface area of ​​the coil component, more preferably 0.007% or more, and even more preferably 0.01% or more, because this makes it easier to flow out the composite magnetic material from the discharge holes 35 during thermal molding. The upper limit is more preferably 1.4% or less of the surface area of ​​the coil component, and even more preferably 1.3% or less, because this makes it easier to increase the density of the obtained coil component.

[0040] The minimum hole diameter of the discharge hole 35 is not limited, but may be 50 μm or more, 60 μm or more, 70 μm or more, or 75 μm or more. The upper limit is also not limited, but may be 2000 μm or less, 1500 μm or less, or 1000 μm or less.

[0041] It is preferable that the discharge hole 35 is formed by a discharge groove 31 provided in the region of the upper die 11 that comes into contact with the lower die 21 or in the region of the lower die 21 that comes into contact with the upper die 11. In other words, the above-mentioned mold has the discharge groove 31 in the region of the upper die 11 that comes into contact with the lower die 21 or in the region of the lower die 21 that comes into contact with the upper die 11, and it is preferable that the discharge groove 31 forms the above-mentioned discharge hole 35 when the upper die 11 and the lower die 21 are brought into contact with each other. This is because, during thermoforming, the composite magnetic material can be easily discharged by the discharge hole 35 provided in the region of contact between the upper die 11 and the lower die 21 (region adjacent to the contact surface), and the mold can also be easily designed and manufactured.

[0042] For example, as in the embodiment shown in Figures 1 and 2, a mold may be exemplified in which a plurality of discharge grooves 31 are provided in both the region of the upper mold 11 that contacts the lower mold 21 and the region of the lower mold 21 that contacts the upper mold 11, and when the upper mold 11 and the lower mold 21 are brought into contact with each other, one discharge groove 31 of the upper mold 11 and one discharge groove 31 of the lower mold 21 are combined to form one discharge hole 35. Also, the mold may have the discharge groove 31 only in the region of the upper mold 11 that contacts the lower mold 21, or only in the region of the lower mold 21 that contacts the upper mold 11. Furthermore, all of the discharge holes 35 of the mold may be formed by the discharge grooves 31. However, this does not exclude the use of a mold having discharge holes 35 in areas other than the contact area between upper mold 11 and lower mold 21 (for example, the side surfaces or top surface of the upper mold, the side surfaces of the lower mold, etc.).

[0043] Furthermore, when the mold has a configuration having a plurality of side peripheral surfaces, it is preferable that, among the plurality of side peripheral surfaces, the pull-out portion protruding surface from which the pull-out portion 103 of the coil protrudes and the discharge hole opening surface from which the discharge hole 35 opens are configured differently, as in the embodiment shown in Figures 1 and 2. This is because, when polishing the surface of the coil component obtained after the compression molding step and the thermosetting step, it is easy to polish the protrusion of the composite magnetic thermosetting molded body formed from the composite magnetic material flowing out from the discharge hole 35.

[0044] Alternatively, as a modified example, the discharge groove 31 may be configured to be integrated with the wiring groove 33 as in the embodiment shown in FIG. 3. In other words, the clearance generated when the coil pull-out portion 103 is placed in the wiring groove 33 and the upper mold 11 and the lower mold 21 are brought into contact with each other may be the discharge hole 35. In this case, the clearance may be a hole diameter that allows the metal magnetic powder to pass through, and the total opening area of ​​the discharge hole 35 including the opening area of ​​the clearance may be 0.003% to 1.5% of the surface area of ​​the coil component. In the embodiment shown in FIG. 3, the wiring groove 33 (discharge groove 31) is configured so that the discharge holes 35 (two discharge holes sandwiching the coil pull-out portion 103) are formed on both sides of the coil pull-out portion 103, but the wiring groove 33 (discharge groove 31) may be configured so that the discharge hole 35 is formed only on one side of the coil pull-out portion 103. However, if this discharge groove 31 is provided separately from the wiring groove 33 (the discharge groove 31 and the wiring groove 33 are separate), the discharge hole 35 will be formed in a region separate from the wiring groove 33, which is preferable because it makes it easier for the pull-out portion 103 of the coil arranged in the wiring groove 33 to be stable during molding.

[0045] The wiring groove 33 may have any configuration as long as it is possible to arrange the lead-out portion 103 of the coil. In particular, it is preferable that the distance between the inner surface of the wiring groove 33 and the lead-out portion 103 of the coil is less than the maximum particle diameter of the metal magnetic powder when the lead-out portion 103 of the coil is arranged. Then, a mold having such wiring groove 33 in both the region of the upper mold 11 that contacts the lower mold 21 and the region of the lower mold 21 that contacts the upper mold 11 (for example, a mold having a configuration in which these can be combined) may be used, or a mold having the wiring groove 33 only in the region of the upper mold 11 that contacts the lower mold 21 or only in the region of the lower mold 21 that contacts the upper mold 11 may be used. Also, a mold in which two or more wiring grooves are formed may be used.

[0046] As for the number of discharge holes 35, it is preferable that the mold has two or more discharge holes 35, because this makes it easier for the composite magnetic material to flow out of the discharge holes 35 during thermoforming. In particular, it is very preferable that the mold has two or more discharge holes 35 in the contact area between the upper mold 11 and the lower mold 21, as shown in Fig. 2.

[0047] Next, the winding portion 101 of a coil (e.g., an air-core coil) is placed inside the prepared mold. Then, as shown in Figs. 1 and 2, the lead-out portion 103 of the coil is placed in the wiring groove 33, and this lead-out portion 103 of the coil is made to protrude from inside the mold. Furthermore, using an injector or the like, the composite magnetic material is filled into the inside of the mold so as to embed the winding portion 101 of the coil (so as to embed the upper and lower spaces, side spaces, and internal space of the winding portion 101). Note that when the composite magnetic material is poured into the mold, it may be poured while applying vibration to the mold in order to prevent the occurrence of areas inside the mold where the composite magnetic material is not sufficiently filled.

[0048] Then, the mold is heated to adjust the temperature, and pressure is applied from both above and below or either one of them with a punch or the like to flow out of the composite magnetic material from the discharge hole 35 while performing compression molding to obtain a composite magnetic molded body containing the coil winding part 101. The mold may be heated before filling with the composite magnetic material. In this thermal molding, a part of the composite magnetic material flows out from the discharge hole 35 as described above by pressure after the composite magnetic material is sufficiently filled in the mold, but since this discharge hole 35 is of a size that allows the metal magnetic powder and the thermosetting resin to pass through in a homogeneous mixture, separation of the metal magnetic powder and the thermosetting resin in the composite magnetic material embedding the coil is unlikely to occur. Therefore, the composite magnetic molded body obtained by this compression molding process has a composition (content of thermosetting resin) that is substantially unchanged from the composite magnetic material before molding.

[0049] For example, when a conventional mold without a discharge hole 35 as shown in FIG. 4 is used, the clearance between the wiring groove 33 and the coil pull-out portion 103 is extremely small, and there is almost no clearance in other parts, so that there is a high possibility that the thermosetting resin in the composite magnetic material will separate and flow into the clearance between the wiring groove 33 and the coil pull-out portion 103 during thermoforming. This will result in a decrease in the content of thermosetting resin in the obtained composite magnetic thermosetting molded body. This may lead to a decrease in the breakdown voltage. On the other hand, if the molding pressure is lowered to prevent such separation of the thermosetting resin, it may be difficult to obtain a molded body (coil component) with a high density. However, since the mold used in the manufacturing method of the coil component according to the present embodiment has the above-mentioned discharge hole 35, the metal magnetic powder in the composite magnetic material in which the coil is embedded and the thermosetting resin are less likely to separate during thermal molding, and the resulting coil component is less likely to experience a drop in breakdown voltage when a DC voltage is applied to the coil component. Furthermore, it is possible to prevent the composite magnetic material from flowing out more than necessary during this thermal molding, making it easy to obtain a high-density molded body (coil component).

[0050] In this compression molding process, the mold is heated to 100°C or higher and 180°C or lower, and the pressure is 3 kgf / cm 2 More than 5000kgf / cm 2 Below (2.94×10N / cm 2 More than 4.9 x 10 4 N / cm 2 It is preferable to perform compression molding at a molding pressure of 1000 MPa (or less) for a time of 10 seconds to 5 minutes. In the manufacturing method of the coil component according to the present embodiment, the compression molding step is performed using the above-mentioned mold, so that even under the above-mentioned molding pressure conditions, the composite magnetic material can be discharged from the discharge hole 35 and a molded body (coil component) with high density can be obtained. Furthermore, when a DC voltage is applied to the obtained molded body (coil component), a decrease in the dielectric breakdown voltage is unlikely to occur.

[0051] Instead of an air-core coil, a coil assembly consisting of a coil and a magnetic core material that serves as the magnetic core may be prepared, and this may be used to perform thermoforming in the same manner as described above. In this case, the magnetic exterior body (outer core material) of the obtained coil component is made of a composite magnetic thermosetting molded body, but the magnetic core (inner core material) is made of a material (e.g., a ferrite core) different from this composite magnetic thermosetting molded body. However, it is more preferable to use a coil component in which both the outer core material and the inner core material are made of this composite magnetic thermosetting molded body.

[0052] [Thermosetting process] The heat curing process is a process in which the composite magnetic molded body containing the coil winding portion 101 obtained in the compression molding process is heat-treated and heat-cured to obtain a coil component in which the coil winding portion 101 is contained in the composite magnetic thermosetting molded body. Specifically, the composite magnetic molded body containing the coil winding portion 101 after the compression molding process is heat-treated at a temperature equal to or higher than the recommended heat curing temperature of the thermosetting resin contained therein to heat-cur it. The temperature of this heat treatment may be appropriately set depending on the type of thermosetting resin contained in the composite magnetic material, and is exemplified by a temperature of 150°C to 230°C, and further 160°C to 200°C. The heat treatment time may be, for example, 0.1 hours to 5 hours, and further 0.2 hours to 3 hours. This heat treatment may be performed in a mold, may be performed after removal from the mold, or may be performed both. Thereafter, the obtained coil component may be selectively subjected to a process such as surface polishing or coating as necessary.

[0053] In this way, it is possible to easily obtain a coil component in which the content of thermosetting resin in the composite magnetic thermosetting molded body containing the coil is maintained (the content of the composite magnetic material and the thermosetting resin are substantially the same). In other words, it is possible to easily manufacture a coil component in which the decrease in the breakdown voltage when a DC voltage is applied is suppressed (for example, the breakdown voltage is 200 V / mm or more).

[0054] In addition, when a coil component is manufactured using a mold in which the discharge groove 31 is integrated with the wiring groove 33 as in the embodiment shown in Fig. 3, the composite magnetic material flows out from the periphery of the lead-out portion 103 of the coil during thermal molding, and the periphery of the lead-out portion 103 of the obtained coil component has a protruding portion formed by thermally curing the remaining part of the composite magnetic material. In other words, a coil component can be obtained in which the periphery of the lead-out portion 103 of the coil has a protruding portion in which a composite magnetic thermosetting molded body having substantially the same composition as the composite magnetic thermosetting molded body on the periphery of the winding portion 101 of the coil protrudes together with the lead-out portion 103. This coil component is likely to have higher resistance to wire bending in the lead-out portion 103 due to the protruding portion on the periphery of the lead-out portion 103.

[0055] The above describes the manufacturing method of the coil component according to the present embodiment. However, the present invention is not limited to the above-described embodiment, and also includes various modifications, improvements, and other embodiments as long as the object of the present invention is achieved. Furthermore, the above-described embodiments can be combined as appropriate without departing from the spirit and scope of the present invention.

[0056] Hereinafter, examples of the present invention will be described. However, the present invention is not limited to the following examples, and as described above, various modifications and the like are possible within the technical concept of the present invention. EXAMPLES

[0057] The metallic magnetic powder used in the composite magnetic material is a nearly spherical Fe-Si-Cr-B amorphous powder (Fe content 86 wt%, Si content 6.7 wt%, Cr content 2.5 wt%, B content 2.5 wt%) with an average particle diameter (D 50 ) is 27μm and the average particle size (D 50 A mixture of powder with an average particle diameter (D ) of 4 μm (maximum particle diameter: 50 μm) was prepared. 50) and maximum particle size were measured using a laser diffraction / scattering type particle size distribution analyzer (particle size distribution) LA-960 (manufactured by HORIBA Seisakusho Co., Ltd.) Furthermore, as the thermosetting resin used in the composite magnetic material, a novolac type epoxy resin to which a required amount of a phenol novolac type hardener was added was prepared.

[0058] First, a predetermined amount of the thermosetting resin was weighed out and diluted with methyl ethyl ketone (MEK) as a solvent. The resin solution was thoroughly dissolved to prepare a resin solution, and a predetermined amount of the metal magnetic powder was mixed into the resin solution and thoroughly stirred and mixed with a planetary mixer. The dilution solvent, methyl ethyl ketone (MEK), was then dried while stirring with the planetary mixer to obtain a mixture of the metal magnetic powder and the thermosetting resin. The mixture was then crushed with a high-speed crusher and then granulated to produce a granulated powder of a composite magnetic material with a mass ratio of the thermosetting resin of 3.0 wt%.

[0059] Separately, an air-core coil was prepared using an insulating-coated copper wire (wire) having a winding portion and an extraction portion from which the wire was extracted.

[0060] Next, a mold was prepared in which, in the region of the upper mold that comes into contact with the lower mold and the region of the lower mold that comes into contact with the upper mold, four discharge grooves were formed by combining two discharge holes of the same size (discharge holes whose cross section perpendicular to the hole is approximately circular and approximately cylindrical) when the upper and lower molds of the mold were brought into contact, and two wiring grooves in which the clearance (the distance between the inner surface of the wiring groove and the lead-out portion of the coil) generated when the lead-out portion of the coil is placed is less than 50 μm. Note that 18 types of this mold were prepared, each with a different shape of the internal space (No. 1 to No. 3) or a different diameter of the discharge hole formed (0.050 mm to 1.000 mm). The surface area a (mm 2 ), the diameter b of one discharge hole of these dies (minimum hole diameter, mm), the total cross-sectional area c of the orthogonal cross sections of the two discharge holes of these dies (total opening area, mm 2), and the ratio c / a (%) of the total cross-sectional area of ​​the two discharge holes of these dies to the surface area of ​​the coil parts produced using these dies are shown in Table 1 below. The winding part of the air-core coil was then placed inside each die, and its lead-out part was placed in the wiring groove, and the granulated powder of the composite magnetic material was filled so that the winding part of the air-core coil was embedded. The temperature of this die was then set to 140°C, and a pressure of 100 kgf / cm was applied by the upper punch. 2 The composite magnetic molded body was compressed for 1 minute at a pressure of 1000 rpm, and then removed from the mold. The composite magnetic molded body was heat-treated at 160°C for 2 hours to heat-set the thermosetting resin (after-cure), and a coil part was obtained as a composite magnetic thermosetting molded body containing a coil.

[0061] The dielectric breakdown voltage (V / mm) of the composite magnetic thermosetting molded body in each coil component obtained was measured by sandwiching both main surfaces of the composite magnetic thermosetting molded body cut to a specified thickness between two copper plate electrodes via a conductive rubber sheet (thickness 0.3 mm) and applying a DC voltage. An insulation resistance meter SM7110 manufactured by Hioki E.E.C. was used for the measurement. The results are also shown in Table 1 below.

[0062] These results show that the composite magnetic thermosetting molded bodies of all coil components had a breakdown voltage of 230 V / mm or more. In other words, it was shown that in all coil components, separation of the metal magnetic powder and the thermosetting resin in the composite magnetic material did not occur during thermoforming, and the coil components were molded and thermoset while maintaining the content of thermosetting resin.

[0063] [Table 1]

[0064] The present embodiment encompasses the following technical ideas. (1) A method for manufacturing a coil component in which a composite magnetic material composed of a metal magnetic powder and a thermosetting resin is molded and thermoset into a composite magnetic thermosetting molded body, the composite magnetic material being formed into a composite magnetic thermosetting molded body, and a wound portion of a coil is encapsulated in the composite magnetic thermosetting molded body, and a lead-out portion of the coil protrudes from the composite magnetic thermosetting molded body, the method comprising the steps of: (a) forming a wiring groove in which the lead-out portion of the coil is disposed in an area of ​​the upper mold that comes into contact with the lower mold or an area of ​​the lower mold that comes into contact with the upper mold; and (b) forming a wiring groove in which the lead-out portion of the coil is disposed in the wiring groove, the wiring groove having a diameter that allows the metal magnetic powder to pass through and a total opening area that is 0.01% of the surface area of ​​the coil component when the lead-out portion of the coil is disposed in the wiring groove and the upper mold and the lower mold are brought into contact with each other. a compression molding process for obtaining a composite magnetic molded body containing the winding portion of the coil; and a heat hardening process for heat-treating the composite magnetic molded body to heat harden it, the composite magnetic molded body being heat-treated to heat harden it, and the coil component being obtained. (2) The method for manufacturing a coil component according to (1), wherein the discharge hole of the mold has a minimum hole diameter that is equal to or larger than the maximum particle diameter of the metal magnetic powder. (3) A method for manufacturing a coil component described in (1) or (2), wherein the mold has an ejection groove in an area of ​​the upper mold that comes into contact with the lower mold or in an area of ​​the lower mold that comes into contact with the upper mold, and the ejection groove forms the ejection hole when the upper mold and the lower mold are brought into contact with each other. (4) The method for manufacturing a coil component described in any one of (1) to (3), wherein the mold has a plurality of side peripheral surfaces, and among the side peripheral surfaces, a drawn-out portion protruding surface from which the drawn-out portion of the coil protrudes and a discharge hole opening surface from which the discharge hole opens are configured differently. (5) In the compression molding step, the mold is heated to 100°C or higher and 180°C or lower, and compressed under a pressure of 3 kgf / cm 2 More than 5000kgf / cm 2The method for producing a coil component according to any one of (1) to (4), comprising compression molding the coil component at the following molding pressure for a period of 10 seconds to 5 minutes. [Explanation of symbols]

[0065] 11 Upper die of the mold 21 Lower die of the mold 31 Discharge groove 33 Wiring groove 35 Discharge hole 101 Coil winding section 103 Coil pull-out section

Claims

1. A method for manufacturing a coil component, comprising: a composite magnetic thermosetting molded body obtained by molding and thermosetting a composite magnetic material composed of a metal magnetic powder and a thermosetting resin; a wound portion of a coil is enclosed in the composite magnetic thermosetting molded body; and a pull-out portion of the coil protrudes from the composite magnetic thermosetting molded body, a die having an upper die and a lower die, a wiring groove for arranging the lead-out portion of the coil in an area of ​​the upper die that comes into contact with the lower die or an area of ​​the lower die that comes into contact with the upper die, and further having one or more discharge holes having a hole diameter that allows the metal magnetic powder to pass through and a total opening area that is 0.003% or more and 1.5% or less of a surface area of ​​the coil component when the lead-out portion of the coil is arranged in the wiring groove and the upper die and the lower die are in contact with each other; a compression molding process in which the winding portion of the coil is disposed inside the mold, the drawn-out portion of the coil is disposed in the wiring groove so that the drawn-out portion of the coil protrudes from inside the mold, the composite magnetic material is filled inside the mold so as to embed the winding portion of the coil, the mold is heated, and the composite magnetic material is compression-molded while flowing out from the discharge hole, thereby obtaining a composite magnetic molded body containing the winding portion of the coil; and a heat curing step of heat-treating the composite magnetic molded body to heat-cure it, thereby obtaining the coil component. A manufacturing method for coil components.

2. The method for manufacturing a coil component according to claim 1 , wherein the discharge hole of the die has a minimum hole diameter equal to or larger than a maximum particle diameter of the metal magnetic powder.

3. 3. The method for manufacturing a coil component according to claim 1, wherein the mold has a discharge groove in an area of ​​the upper mold that comes into contact with the lower mold or in an area of ​​the lower mold that comes into contact with the upper mold, and the discharge groove forms the discharge hole when the upper mold and the lower mold are brought into contact with each other.

4. The method for manufacturing a coil component according to any one of claims 1 to 3, wherein the mold has a plurality of side peripheral surfaces, and among the side peripheral surfaces, a drawn-out portion protruding surface from which the drawn-out portion of the coil protrudes and a discharge hole opening surface from which the discharge hole opens are configured differently.

5. In the compression molding step, the mold is heated to 100° C. or higher and 180° C. or lower, and a pressure of 3 kgf / cm 2 More than 5000kgf / cm 2 The method for producing a coil component according to any one of claims 1 to 4, wherein compression molding is performed at a molding pressure of at least 10 seconds and at most 5 minutes.

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