WO2010103852A1 - Thermally conductive material, process for producing same, and inductor for high current - Google Patents

Abstract

A material having a composition which comprises a thermosetting resin binder, a dispersant incorporated therein in an amount in the range of 1-180 wt.% per 100 wt.% the thermosetting resin binder, and a thermally conductive filler evenly dispersed therein in an amount in the range of 350-2,000 wt.% per 100 wt.% the thermosetting resin binder, the filler having a particle diameter in the range of 0.1-100 µm, and which makes the material at least have a thermal conductivity of 3.5 W/(m∙K) or higher and a viscosity at 60ºC or lower of 0.2-100 Pa∙s.

Description

Thermally conductive material, method for producing the same, and inductor for large current

The present invention relates to a heat conductive material in which a heat conductive filler is mixed with a thermosetting resin binder, a method for manufacturing the heat conductive material, and a large current inductor using the heat conductive material.

Generally, a hybrid vehicle, a fuel cell vehicle, and the like are equipped with a large current inductor capable of flowing a large current, and a reactor device disclosed in Patent Document 1 is known as such a large current inductor. ing. By the way, this type of large current inductor (reactor device) accommodates an iron core and a coil wound around the iron core in a package, and further protects the potting material by filling it. Sufficient thermal conductivity and heat dissipation are required to release heat generated from the coil through which the gas flows.

For this reason, conventionally, there is also known a heat conductive material for mixing a heat conductive filler in a binder to efficiently conduct and dissipate heat generated by an electrical component. Patent Document 2 has fluidity. A heat conductive sheet obtained by filling a rubber with a heat conductive filler and kneading and molding the heat conductive filler having an average particle diameter of 50 to 100 μm and an average particle diameter of 10 μm or less in a weight ratio of 1: A heat conductive sheet mixed at a ratio of 1 to 3: 1 is disclosed, and Patent Document 3 discloses wax and / or paraffin having a melting point of 40 to 100 ° C., a thermoplastic resin softened at 40 to 100 ° C., A highly thermally conductive composition obtained by mixing spherical alumina having a sphericity of 0.78 or more and an average particle diameter of 3 μm or more is disclosed.

JP 2004-193398 A JP 2001-139733 A JP 2002-003830 A

However, the conventional heat conductive material in which the above-mentioned binder is mixed with the heat conductive filler has the following problems.

First, because it tends to be specialized in the use and use of heat conductive materials, such as interposing between the surface of an electronic component (electrical component) and a heat sink, it was applied to other electronic components. In some cases, there is a drawback that is not always best matching. For example, in the case of a component having many minute gaps such as a large current inductor, an unfilled gap may be generated. In this case, the heat conduction efficiency and the heat radiation efficiency are lowered.

Secondly, in order to enhance the filling property in the minute gaps, if the heat conductive material is made fluid, it becomes difficult to apply a share when mixing and stirring the binder and the heat conductive filler. That is, since it becomes difficult to knead | mix, it becomes difficult to mix a heat conductive filler with a high density with respect to a binder, and to make it disperse | distribute uniformly. Eventually, in this case as well, the heat conduction efficiency and the heat dissipation efficiency are lowered, and the quality (homogenization) of the heat conductive material itself is liable to be lowered.

An object of the present invention is to provide a thermally conductive material, a method for manufacturing the same, and an inductor for large current that solve the problems existing in the background art.

In order to solve the above-described problems, the thermally conductive material Ri according to the present invention is a thermally conductive material in which a thermally conductive filler is mixed with a thermosetting resin binder. A dispersant selected in the range of 1 to 180 [wt%] is blended with 100 [wt%], and 350 to 2000 [wt%] with respect to 100 [wt%] of the thermosetting resin binder. The thermally conductive filler having a particle size of 0.1 to 100 [μm] is uniformly dispersed, and at least the thermal conductivity is 3.5 [W / (m · K)] or more, The composition is characterized in that the viscosity is 0.2 to 100 [Pa · s] at a temperature of 60 ° C. or lower.

Moreover, the manufacturing method of the heat conductive material which concerns on this invention, when mix | blending a heat conductive filler with a thermosetting resin binder and manufacturing heat conductive material Ri, the said thermosetting resin binder is made into the said thermosetting resin. A dispersant selected in the range of 1 to 180 [wt%] is blended with the resin binder 100 [wt%], and 350 to 2000 [wt%] with respect to the thermosetting resin binder 100 [wt%]. The heat conductive filler selected in the range of 0.1 to 100 [μm] is mixed and stirred to uniformly disperse the heat conductive filler, and at least the heat conductivity is 3 It is characterized in that a composition having a viscosity of 0.2 to 100 [Pa · s] at a temperature of not less than 5 [W / (m · K)] and a temperature of 60 [° C.] or less is obtained.

Furthermore, the large current inductor 1 according to the present invention accommodates one or more coils 2 wound with a vertical rectangular conductor, a core 3 loaded on the coil 2, and a coil 2 loaded with the core 3. In addition, in the inductor including the package 4 formed of a heat conductive material, the thermosetting resin binder is selected from 1 to 180 [wt%] with respect to 100 [wt%] of the thermosetting resin binder. In addition, the dispersant is blended, and the particle size is selected in the range of 350 to 2000 [wt%] and the particle diameter in the range of 0.1 to 100 [μm] with respect to 100 [wt%] of the thermosetting resin binder. The thermally conductive filler is uniformly dispersed, and at least 0.2 to 100 [Pa · s] when the thermal conductivity is 3.5 [W / (m · K)] or more and the viscosity is 60 [° C.] or less. Having a composition The conductive material Ri, characterized by comprising filling a potting material 5 inside of the package 4.

On the other hand, according to a preferred embodiment of the present invention, the thermosetting resin binder in the heat conductive material Ri includes at least an epoxy resin having a viscosity selected in the range of 0.01 to 1 [Pa · s]. Can be made. The thermosetting resin binder can include a resin binder using one liquid or a resin binder using at least two liquids including a main agent and a curing agent. Further, the heat conductive filler can have electrical insulation. Therefore, the thermally conductive filler can include at least a single material or a composite material using one or more of magnesium oxide, aluminum oxide, silicon oxide, aluminum nitride, and boron nitride. A single particle size or a plurality of different particle sizes can be included. On the other hand, as the coil 2 in the large current inductor 1, a coil produced by sequentially folding the coil pattern plate As continuously formed of a sheet material can be used. In addition, at least a part of one or two or more surfaces of the coil 2, the core 3, and the package 4, at least a resin binder, 0.01 to 50 [wt] with respect to 100 [wt%] of the resin binder. %] In the range of 100 to 600 [wt%] and the particle size in the range of 0.1 to 20 [μm] with respect to 100 [wt%] of the resin binder. The heat conductive filler selected in (1) is uniformly dispersed, at least the dielectric breakdown strength is 14 [kV / mm] (however, 10 [kHz], the breaking current is 10 [mA]) and the viscosity is 0.05 to 3 The heat dissipating insulating material Rc having a composition of [Pa · s] can be coated as the coating agent 6. In addition, it is desirable to use a silicone resin binder for this resin binder.

According to the heat conductive material Ri and the manufacturing method thereof and the large current inductor 1 according to the present invention as described above, the following remarkable effects can be obtained.

(1) In the heat conductive material Ri, a dispersant selected in the range of 1 to 180 [wt%] with respect to 100 [wt%] of the thermosetting resin binder is added to the thermosetting resin binder. The heat conductive filler selected in the range of 350 to 2000 [wt%] and the particle size in the range of 0.1 to 100 [μm] with respect to 100 [wt%] of the thermosetting resin binder is uniform. Since it has a composition that is dispersed and has a thermal conductivity of 3.5 [W / (m · K)] or more and a viscosity of 0.2 to 100 [Pa · s] at a temperature of 60 ° C. or less, For example, even in the case of parts with many minute gaps, there is no risk of unfilled gaps, and heat conduction efficiency and heat dissipation efficiency can be improved, and versatility can be improved. Improved quality (homogenization) of conductive material Ri Also it can contribute.

(2) The large current inductor 1 accommodates one or more coils 2 wound with a vertical rectangular conductor, a core 3 loaded on the coil 2, and a coil 2 loaded with the core 3. The package 4 made of a heat conductive material is provided, and the inside of the package 4 is filled with the heat conductive material Ri as the potting material 5, so that the heat conduction performance between the coil 2 (core 3) and the package 4 is further enhanced. In addition, the protection performance for the coil 2 and the durability of the large current inductor 1 can be further enhanced.

(3) According to a preferred embodiment, when an epoxy resin selected at least in the range of 0.01 to 1 [Pa · s] is used as the thermosetting resin binder, heat conduction to the low viscosity epoxy resin is achieved. Since the conductive filler is mixed, the uniform dispersion of the heat conductive filler can be further optimized.

(4) According to a preferred embodiment, if the thermally conductive filler has electrical insulation, a coating agent or potting material that is more desirable for electronic components (electrical components) can be obtained.

(5) According to a preferred embodiment, if a single material or a composite material containing at least one of magnesium oxide, aluminum oxide, silicon oxide, aluminum nitride, and boron nitride is used as the thermally conductive filler, Greater performance can be obtained from the viewpoint of ensuring good thermal conductivity and heat dissipation.

(6) If a thermally conductive filler having a plurality of different particle diameters is used according to a preferred embodiment, when the thermally conductive filler is uniformly dispersed at a high density in the thermosetting resin binder, From the viewpoint of increasing the thermal conductivity (heat dissipation), further optimization can be achieved.

(7) According to a preferred embodiment, when the thermosetting resin binder includes a resin binder using one liquid or a resin binder using at least two liquids including a main agent and a curing agent, the heat conductive material Ri can be manufactured. Further, the reactivity and handling at the time of production can be made more flexible.

(8) According to a preferred embodiment, if a coil produced by sequentially folding coil pattern plates As continuously formed of a sheet material is used for the coil 2 of the high-current inductor 1, the manufacturing process can be simplified and simplified. Since the manufacturing man-hours associated therewith can be reduced, it is possible to improve the mass productivity and the low cost related to the high current inductor 1. Moreover, since the corner | angular part of the coil 2 can be made into a right angle, thermal conductivity and thermal radiation can be improved more by the further flattening of the inductor 1 for large currents.

(9) According to a preferred embodiment, the resin binder is blended with a dispersant selected in the range of 0.01 to 50 [wt%] with respect to the resin binder 100 [wt%], and the resin binder 100 [wt %], The thermally conductive filler selected in the range of 100 to 600 [wt%] and the particle size in the range of 0.1 to 20 [μm] is uniformly dispersed, and at least the dielectric breakdown strength is A heat dissipating insulating material Rc having a composition of 14 [kV / mm] (10 [kHz], breaking current 10 [mA]) or more and a viscosity of 0.05 to 3 [Pa · s] , Core 3, package 4, if a part or all of one or more surfaces are coated as coating agent 6, a heat-dissipating insulating material having a predetermined thickness for coil 2, core 3, and package 4 Rc With a coating layer can be provided easily and reliably, it is possible to coil 2, increase the core 3 and the package 4 itself thermal conductivity and heat dissipation. At this time, if a silicone-based resin binder is used as the resin binder, more desirable performance can be obtained from the viewpoint of improving the thermal conductivity and heat dissipation of the coil 2, the core 3 and the package 4 itself.

Manufacturing process diagram of a thermally conductive material according to the best embodiment of the present invention, The manufacturing process figure of the heat-radiating insulating material used for the inductor for large currents according to the best embodiment of the present invention, The perspective view which shows the principle structure of the coil used for the inductor for the same large current, Plan view of the intermediate assembly of the same high-current inductor, Front sectional view of the same large current inductor, Viscosity characteristic diagram with respect to temperature of raw materials used for the heat conductive material, Mass reduction rate characteristic diagram with respect to heating time of heat-dissipating insulating material used for the same high-current inductor, Dielectric breakdown strength characteristic diagram with respect to heating time of the heat-dissipating insulating material, Figure of rising temperature characteristics with respect to operating time of the inductor for the same large current, Manufacturing process diagram showing a part of the thermally conductive material according to a modified embodiment of the present invention, Filler filling rate vs. thermal conductivity characteristics diagram used for the thermally conductive material, Example of heat conductive material and temperature vs. viscosity characteristic diagram of commercially available product, Examples of thermal conductive materials and evaluation test result table of commercially available products, Figure of rising temperature characteristics with respect to operating time when using the same thermally conductive material for high current inductors,

1: Inductor for large current, 2: Coil, 3: Core, 4: Package, 5: Potting material, 6: Coating agent, Ri: Thermally conductive material, Rc: Heat radiation insulating material, As: Coil pattern plate

Next, the best embodiment according to the present invention will be given and described in detail with reference to the drawings.

First, the thermal conductive material Ri according to the present embodiment and the manufacturing method thereof will be described with reference to the manufacturing process diagram shown in FIG. 1 and FIG.

In the heat conductive material Ri, basically, a dispersing agent selected in the range of 1 to 180 [wt%] with respect to 100 [wt%] of the thermosetting resin binder is blended in the thermosetting resin binder. In addition, a thermally conductive filler selected in the range of 350 to 2000 [wt%] and the particle size in the range of 0.1 to 100 [μm] with respect to 100 [wt%] of the thermosetting resin binder is provided. It has a uniformly dispersed composition. Therefore, when manufacturing the heat conductive material Ri, a thermosetting resin binder, a dispersant, and a heat conductive filler as raw materials are prepared.

As the thermosetting resin binder, an epoxy resin having a relatively high heat resistance as an organic material, in particular, an epoxy resin composed of a main agent and a curing agent (a two-component mixed thermosetting type) is used. Various curing agents such as acid anhydrides, polyamines, and imidazoles can be used as the curing agent. When an epoxy resin composed of such a main agent and a curing agent is used, the reactivity and handling at the time of production can be made more flexible when producing the heat conductive material Ri. As the main agent and the curing agent, low viscosity epoxy resins having a viscosity selected in the range of 0.01 to 1 [Pa · s] are used. Thereby, since the heat conductive filler mentioned later can be mixed with the epoxy resin of comparatively low viscosity, the uniform dispersion | distribution of a heat conductive filler can be optimized more. FIG. 6 shows the relationship between the temperature [° C.] and the viscosity [Pa · s] of the raw materials (main agent and curing agent). In FIG. 6, Mim shows the characteristics of the main agent (epoxy resin) used in this embodiment, Mih. Shows the characteristics of the curing agent used in this embodiment. In FIG. 6, Mam and Mah are characteristics of a commercially available general main agent (epoxy resin) and a curing agent, and Mbm and Mbh are other general main agents (epoxy resin) and a curing agent that are commercially available. This is a characteristic and is shown as a comparative example. Neither of them is sufficient as a heat conductive material used for a potting material of a large current inductor. As the thermosetting resin binder, epoxy resin is desirable, but in addition, when heat resistance is required, silicone resin can be used, and when heat resistance is not required, urethane resin Phenol resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, thermosetting polyimide resin, etc. can also be used.

The dispersing agent is selected in the range of 1 to 180 [wt%] with respect to 100 [wt%] of the main agent or curing agent. In this case, various known dispersants can be used as the dispersant, and the dispersant is not limited to a specific dispersant. If a suitable amount of dispersant is blended with the main agent or curing agent, it becomes possible to achieve good dispersibility even when a high-density thermal conductive filler described later is mixed with the main agent or curing agent. The densification of the heat conductive filler with respect to the main agent or the curing agent can be made more uniform.

マ グ ネ シ ウ ム Use a single material of magnesium oxide for the thermally conductive filler. Magnesium oxide is excellent in cost merit, has high thermal conductivity, and has electrical insulation. By providing electrical insulation, it is possible to obtain a coating agent or potting material that is more desirable for electronic components (electrical components). The magnesium oxide particles used as the heat conductive filler are selected in the range of 350 to 2000 [wt%] with respect to 100 [wt%] of the main agent or curing agent. Further, the particle diameter of the magnesium oxide particles is selected in the range of 0.1 to 100 [μm], and it is particularly desirable to include a plurality of different particle diameters. In this embodiment, a large filler of about 5 to 100 [μm], a medium filler of about 0.5 to 20 [μm], and a small filler of about 0.1 to 10 [μm] are mixed. Of course, a single particle diameter may be used as long as the particle diameter is in the range of 0.1 to 100 [μm]. In addition, instead of magnesium oxide particles, a single material of aluminum nitride particles or boron nitride particles, or aluminum oxide particles or silicon oxide particles may be used. Magnesium oxide particles, aluminum nitride particles, boron nitride particles, oxidation A composite material including two or more of aluminum particles and silicon oxide particles may be used. As described above, if a single material or a composite material containing at least one of magnesium oxide, aluminum nitride, boron nitride, aluminum oxide, and silicon oxide is used for the thermally conductive filler, good thermal conductivity is obtained. In addition, from the viewpoint of ensuring heat dissipation, greater performance can be obtained, and if fillers having a plurality of different particle sizes are selected, each filler is uniformly dispersed at a high density with respect to the main agent or curing agent as a binder. In doing so, the mixture of different particle sizes can be further optimized from the viewpoint of enhancing thermal conductivity (heat dissipation). As the thermal conductive filler, other various ceramic particles such as silicon nitride, titanium oxide, zirconium oxide, tin oxide, zinc oxide and silicon carbide that can ensure electrical insulation and thermal conductivity can be used depending on the application. is there.

Next, a specific manufacturing procedure will be described. First, prior to mixing the main agent and the curing agent, the main agent solution and the curing agent solution are separately prepared in advance. In producing the main agent solution, first, the prepared dispersant is blended with the prepared main agent (epoxy resin) (steps S1 and S2). Next, the prepared magnesium oxide particles (thermally conductive filler) are mixed (steps S2 and S3). And the obtained mixed solution fully stirs with a stirring apparatus, and performs sufficient defoaming with a defoaming apparatus (process S4). Thereby, a main agent solution in which high-density magnesium oxide particles are uniformly dispersed with respect to the epoxy resin (main agent) can be obtained (step S5). Similarly, when manufacturing the curing agent solution, first, the prepared dispersant is blended with the prepared curing agent (steps S6 and S7). Next, the prepared magnesium oxide particles are mixed (steps S7 and S8). And the obtained mixed solution fully stirs with a stirring apparatus, and performs sufficient defoaming with a defoaming apparatus (process S9). Thereby, the hardening | curing agent solution in which a high-density magnesium oxide particle is uniformly disperse | distributed with respect to a hardening | curing agent can be obtained (process S10).

Next, the obtained main agent solution and curing agent solution are mixed while being appropriately stirred (steps S5, S10, S11). As a result, a target thermal conductive material Ri having a total viscosity of 0.2 to 100 [Pa · s] can be obtained (step S12). The heat conductive material Ri having a viscosity of 0.2 to 100 [Pa · s] is optimal as the potting material 5 of the inductor 1 for large current described later. In the heat conductive material Ri according to this embodiment, the heat conductive material Ri 4.12 [W / (m · K)] with a conductivity of 3.5 [W / (m · K)] or more is ensured, and the dielectric breakdown strength is 7 [kV / mm] (however, In addition to optimum viscosity, such as 10 [kHz] and a breaking current of 10 [mA]), sufficient heat conductivity and electrical insulation as the potting material 5 can be secured. The step (S12) of mixing the main agent solution and the curing agent solution is injected into the package 4 (case portion 4p) immediately before actual use, that is, when used as the potting material 5 of the inductor 1 for large current. (Just before filling).

Thus, according to the thermally conductive material Ri and the manufacturing method thereof according to the present embodiment, the thermosetting resin binder is 1 to 180 [wt%] with respect to 100 [wt%] of the thermosetting resin binder. In the range of 350 to 2000 [wt%] and a particle size of 0.1 to 100 [μm] with respect to 100 [wt%] of the thermosetting resin binder. The heat conductive filler selected in the range is uniformly dispersed, at least the thermal conductivity is 3.5 [W / (m · K)] or more, and the viscosity is 0.2 to 100 [Pa · s]. Since it has a composition, for example, even in the case of a part with many minute gaps, there is no risk of unfilled gaps, and it is possible to improve heat conduction efficiency and heat dissipation efficiency and increase versatility. In addition, heat conductive material R Also it can contribute to the quality (homogenization) improve.

Next, a high-current inductor 1 according to the present preferred embodiment using such a heat conductive material Ri will be described with reference to FIGS.

Since the heat conductive material Ri is used as the potting material 5 for the high current inductor 1, first, FIG. 4 shows a method of manufacturing the intermediate assembly 1m of the high current inductor to which the potting material 5 is used. The description will be given with reference.

First, the coil 2, the core 3 and the package 4 which are the main parts are manufactured. When the coil 2 is manufactured, a hoop base material made of a copper material having a thickness of about 0.5 to 1.0 [mm] and a width corresponding to the design specifications of the coil 2 is prepared. And this hoop base material is supplied to a predetermined coil manufacturing machine. In the coil manufacturing machine, a hoop base material is punched out by a pressing process to obtain a coil pattern plate As continuously formed from a sheet material as shown in FIG. This coil pattern plate As has coil pattern portions 2pc,... Constituting one turn, and connection pattern portions 2jx, 2ji, which connect the coil pattern portions 2pc. The connection pattern portions 2jx, 2ji,... Have two types of connection pattern portions 2jx, 2ji,... With different lengths (offset lengths) protruding from the coil pattern portions 2pc, and are alternately provided. The width (maximum part) of the illustrated coil pattern portions 2pc is 10 [mm]. The coil pattern plate As performs rounding with a predetermined curvature at all corners (corner portions) and performs a burr-free process that does not cause burrs on all edge portions. These rounding and burr-free treatment can be performed simultaneously with the pressing step or in the subsequent step of the pressing step. By performing such rounding and burr-free treatment, a coating agent described later can be uniformly coated.

Next, a folding process is performed in which the coil pattern plate As is sequentially folded by a folding process. In this case, two positions in the connection pattern portions 2jx, 2ji,..., That is, end positions K1... And intermediate portion positions K2 of the connection pattern portions 2jx, 2ji. As a result, the coil pattern portions 2pc... Are sequentially stacked, and the coil 2 shown in FIGS. 4 and 5 can be manufactured. At this time, the two types of connection pattern portions 2jx, 2jy, 2jx, 2jy... Are arranged at positions offset from each other when viewed in the axial direction, and the overlapping of both is avoided. Therefore, the thickness of the connection pattern portions 2jx... 2jy. If such a coil 2 is used, the manufacturing process can be simplified and simplified, and the manufacturing man-hours associated therewith can be reduced. Therefore, it is possible to improve the mass productivity of the high-current inductor 1 and the low cost. realizable. In particular, since the coil pattern plate As can be produced by sequentially folding back, the number of turns in producing a coil obtained between any turns can be increased to 1 turn (360 °), and the winding efficiency can be increased. Since the shapes when punching are aligned in one direction, the coil manufacturing machine (manufacturing process) can be simplified, and the manufacturing cost can be reduced and the manufacturing accuracy can be improved. Moreover, since the corner | angular part of the coil 2 can be made into a right angle, thermal conductivity and thermal radiation can be improved more by the further flattening of the inductor 1 for large currents. In addition, since there is no folded portion inside the coil 2 itself when the coil 2 is manufactured, it is possible to increase the magnetic efficiency as a magnetic circuit, and it is advantageous in reducing the size and size (thinning). Become. Moreover, the degree of freedom in design can be drastically increased, for example, the overall shape of the coil portion 2 can be selected as an arbitrary shape. And the obtained coil 2 is coated with a coating agent using the heat-dissipating insulating material Rc.

Next, a method for manufacturing the heat-radiating insulating material Rc serving as a coating agent and a method for coating the coil 2 will be described with reference to the manufacturing process diagram shown in FIG. 2 and FIGS.

First, a method for manufacturing the heat-radiating insulating material Rc will be described. This heat dissipating insulating material Rc also basically has the same composition structure as that of the above-described heat conductive material Ri, and the silicone resin binder has 0% with respect to 100 [wt%] of the silicone resin binder. A dispersant selected in the range of 0.01 to 50 wt% is blended, and the particle size is 0.1 to 100 wt% with respect to 100 wt% of the silicone resin binder. It has a composition in which the thermally conductive filler selected in the range of ˜20 [μm] is uniformly dispersed. Therefore, in manufacturing the heat-radiating insulating material Rc, a silicone resin binder, a dispersant, a diluting solvent, and a heat conductive filler are prepared as raw materials.

For the silicone resin binder, a low-viscosity silicone resin with a relatively high heat resistance, which is an organic material, is used. When a low-viscosity silicone resin is used, the uniform dispersion of the thermally conductive filler can be further optimized when the thermally conductive filler described later is mixed. Silicone resin is desirable as the binder, but as an alternative to silicone resin, epoxy resin can be used when heat resistance is required, and urethane resin or phenol resin when heat resistance is not required Melamine resin, urea resin, unsaturated polyester resin, alkyd resin, thermosetting polyimide resin, etc. can also be used.

As the dispersant and the diluent solvent, various known dispersants and various known diluent solvents can be used, and are not limited to specific dispersants and diluent solvents. In this case, the dispersing agent is selected in the range of 0.01 to 50 [wt%] with respect to 100 [wt%] of the silicone resin (thermosetting resin binder), and the diluent solvent is used for adjusting the viscosity. . Therefore, when it is not necessary to adjust the viscosity, a diluting solvent is also unnecessary, and this diluting solvent may be used as necessary. Thus, if an appropriate amount of dispersant is blended with the silicone resin, it becomes possible to achieve good dispersibility even when the silicone resin is mixed with a high-density thermally conductive filler described later, The densification of the heat conductive filler with respect to the silicone resin can be made more uniform.

熱 A single material of magnesium oxide and silicon oxide (silica) particles with high electrical insulation are used in combination for the thermally conductive filler. Magnesium oxide is excellent in cost merit, has high thermal conductivity, and also has electrical insulation. It is desirable that the magnesium oxide particles used as the thermally conductive filler have a particle size selected in the range of 0.1 to 20 [μm] and that the silicon oxide particles have a plurality of different particle sizes. In the present embodiment, a mixed material (composite material) of medium filler of about 1 to 20 [μm] and small filler of about 0.1 to 10 [μm] is used. Then, with respect to 100 [wt%] of the silicone resin, the entire magnesium oxide particles and silicon oxide particles are selected in the range of 100 to 600 [wt%], preferably around 195 [wt%]. Of course, a single particle size may be used as long as the particle size is in the range of 0.1 to 20 [μm]. In addition, although the composite material of the magnesium oxide particle and the silicon oxide particle was used for the heat conductive filler, this heat conductive filler may be composed of only one of the magnesium oxide particles and the silicon oxide particles. In addition, instead of magnesium oxide particles or silicon oxide particles, a single material of aluminum nitride particles, boron nitride particles, aluminum oxide particles may be used, or magnesium oxide particles, aluminum nitride particles, boron nitride particles, silicon oxide A composite material including two or more of particles and aluminum oxide may be used. As described above, when a single material or a composite material containing at least one of magnesium oxide, aluminum nitride, boron nitride, silicon oxide particles, and aluminum oxide particles is used as the thermally conductive filler, good heat can be obtained. From the viewpoint of ensuring conductivity and heat dissipation, it is possible to obtain greater performance, and if fillers having a plurality of different particle sizes such as silicon oxide particles are selected, each filler can be used for the silicone resin as a binder. Can be further optimized from the viewpoint of improving thermal conductivity (heat dissipation) by mixing different particle diameters. As the thermal conductive filler, other various ceramic particles such as silicon nitride, titanium oxide, zirconium oxide, tin oxide, zinc oxide and silicon carbide that can ensure electrical insulation and thermal conductivity can be used depending on the application. is there.

Next, a specific manufacturing procedure will be described. First, the prepared dispersing agent, diluent solvent, magnesium oxide particles and silicon oxide particles are blended (mixed) with the prepared silicone resin (thermosetting resin binder) (steps S21, S22, S23, S24, S25). . And it fully stirs with a stirring apparatus (process S26). At this time, beads having a specific gravity remarkably different from that of the heat conductive filler are added to the material to be stirred, and the magnesium oxide particles and silicon oxide particles are uniformly dispersed using a stirring method capable of uniform dispersion such as planetary stirring. Is desirable. In addition, the entire viscosity is adjusted to about 1 [Pa · s] by blending an appropriate amount of a diluting solvent, and sufficient defoaming is performed by a defoaming device for bubbles generated during stirring (step S27). . Thereby, the heat-radiating insulating material Rc having a high density structure in which the magnesium oxide particles and the silicon oxide particles are uniformly dispersed in the silicone resin can be obtained (step S28).

Table 1 shows the characteristics (performance) of the heat-dissipating insulating material Rc obtained. In addition, the characteristic (performance) of the heat-radiation insulating material Rr using the polyamideimide resin generally marketed as a heat-resistant insulating coating agent of the same use as a comparative example was shown.

FIG. 7 shows the heating time [H] (250) of the heat-dissipating insulating material Rr using a polyamideimide resin that is generally commercially available as a heat-resistant insulating coating agent having the same use as the comparative heat-releasing insulating material Rc. 8 shows the characteristics of the mass reduction rate [%] with respect to [° C.], and FIG. 8 shows the heating time [H] (200 [° C.] of the heat dissipating insulating material Rc and the heat insulating insulating material Rr as a comparative example ) Shows the characteristics of dielectric breakdown strength [kV / mm]. As is apparent from Tables 1, 7, and 8, the heat dissipating insulating material Rc according to the present embodiment has a thermal conductivity of 1.30 [sufficient for the coil 2, the core 3, and the package 4 of the large current inductor. W / (m · K)] or more is secured, and 14 [kV / mm] (10 [kHz, breaking current 10 [mA]) or more is secured, which is sufficient for dielectric breakdown strength. Also, the mass reduction rate, which is an evaluation of heat resistance, is ensured to be within -3 [%] at 1000 hours. Further, in the thermal stability evaluation (heat cycle test), no peeling or cracking was observed even after 3000 times (−30 to 200 ° C.).

Next, a coating method for coating the surface 2f of the coil 2 described above using the heat-dissipating insulating material Rc as the coating agent 6 will be described.

The coating process is performed by a dip coating process in which the coil 2 is dipped in a dip tank containing the heat-radiating insulating material Rc (step S29). In this case, the lead portions at both ends of the coil 2 are gripped by a chuck or the like, and dipping is performed with a gap between each conductor turn portion 2m. In the dip coating process, since the thickness of the coating layer is determined by the lifting speed from the dip tank, the lifting speed is set in advance. The pulling speed can be set in the range of 0.1 to 2.0 [mm / s] so that the thickness of the coating layer is about 60 to 80 [μm]. In addition, various coating processes such as a spray coating process and an electrodeposition coating process can be used for the coating process.

Thereafter, the coil 2 coated with the heat dissipating insulating material Rc is fired. The firing treatment is performed in an environment where the firing temperature is set to 200 [° C.] and the firing time is set to 15 [min]. As a result, the coil 2 in which a coating layer having a thickness of 60 to 80 μm is provided on the surface of the coil 2 can be obtained. By performing such dip coating treatment and firing treatment, the coating of the heat-radiating insulating material Rc on the coil 2 and the formation of the coating layer on the coil 2 can be easily and reliably performed. Thus, even a coil having a shape portion that is difficult to apply, such as the coil 2 manufactured by sequentially folding the coil pattern plate As that is continuously formed, can be easily and uniformly coated.

On the other hand, the entire core 3 is manufactured in a donut shape. In this case, the core 3 is a laminated core in which silicon steel plates are laminated, but may be a sintered core using an integrally sintered amorphous material or the like. The core 3 is configured by a combination of a plurality (two in the illustrated example) of the core dividing portions 3a and 3b so that the coil 2 can be mounted. And the core 3 (core division | segmentation part 3a, 3b) also dip-coats using the dip tank which accommodated heat dissipation insulating material Rc similarly to the coil 2 (process S30). In this case, basically, the coating process is performed so that the thickness of the coating layer is about 60 to 80 [μm] as in the above-described coating process of the coil 2. A baking process is performed.

The package 4 includes a case portion 4p that opens upward to accommodate the coil 2, and a cover portion 4c that covers the opening of the case portion 4p. The case portion 4p and the cover portion 4c are integrally formed of a heat conductive material, for example, an aluminum material. Further, the obtained case portion 4p and cover portion 4c are subjected to a coating treatment with the heat-dissipating insulating material Rc (step S31). In this case, a dip coating process is performed to dip the case portion 4p and the cover portion 4c into the dip tank containing the heat-radiating insulating material Rc. In the dip coating process, basically, the coating process is performed so that the thickness of the coating layer is about 60 to 80 [μm], as in the above-described coating process of the core dividing section 3a. A baking process is performed on the case portion 4p and the cover portion 4c. Therefore, through these processing steps, it is possible to obtain a package 4 in which a coating layer having a predetermined thickness is provided on the surface 4f of the case portion 4p and the cover portion 4c (package 4).

Then, if these coils 2, cores 3, and packages 4 are obtained, intermediate assembly is performed (step S32). First, a coil assembly is manufactured by assembling the core dividing portions 3a and 3b to the coil 2. In this case, a pair of coil parts 21 and 22 are used for the coil 2, and each core division | segmentation part 3a, 3b is each accommodated in the internal space of the coil parts 21 and 22, and each core division part 3a, 3b mutual A separator sheet made of glass epoxy resin having a thickness of about 1 mm is interposed therebetween, and the core divided portions 3a and 3b are bonded to each other using an adhesive. Thereby, the coil 2 to which the core 3 is attached, that is, a coil assembly as shown in FIG. 4 is obtained. Further, one end of each of the coil portions 21 and 22 is connected by an intermediate lead 18m, and the other end of each of the coil portions 21 and 22 is connected to an end portion of the lead-out leads 18p and 18n, respectively. Further, the obtained coil assembly is accommodated in the case portion 4p as shown in FIG. At this time, for example, a plurality of holding members 17 using silicon rubber or the like are laid on the inner bottom surface of the case portion 4p, and the coil assembly (coil 2) is placed thereon. If necessary, similar holding members 17 may be interposed between the inner wall portion of the case portion 4p and the coil 2. Thereby, the intermediate assembly 1m of the high-current inductor 1 can be obtained (steps S33 and S13).

Next, the above-described thermally conductive material Ri is filled (injected) into the case portion 4p as the potting material 5 (step S14). And the hardening process with respect to the potting material 5 is performed by heating at the temperature corresponding to the curing temperature of the epoxy resin used for the heat conductive material Ri (process S15). At this time, sufficient defoaming is performed by a defoaming apparatus (step S16). When the curing process for the potting material 5 is completed, final assembly is performed (step S17). In this case, the cover portion 4c is placed on the case portion 4p and fixed by a plurality of fixing screws 16. 15 are screw holes on the side of the case portion 4p to which the fixing screws 16 are screwed. Further, as shown in FIG. 5, the leading ends of the lead leads 18p and 18n are led to the outside through an opening provided in the cover 4c. Through the above manufacturing steps, the intended high current inductor 1 shown in FIG. 5 can be obtained (step S18).

FIG. 9 shows the rising temperature characteristics of each part with respect to the operating time [minute] when the obtained large current inductor 1 is energized. Tci is the surface temperature of the coil 2 in the present embodiment, Tcr is the surface temperature of the coil 2 in the comparative example, Tbi is the surface temperature of the core 3 in the present embodiment, Tbr is the surface temperature of the core 3 in the comparative example, and Tpi is the present embodiment The surface temperature and Tpr of the package 4 in the form respectively indicate the surface temperature of the package 4 in the comparative example. In this case, the present embodiment is an inductor 1 using the heat conductive material Ri and the heat dissipating insulating material Rc, and the comparative example is an inductor using the heat conductive material Rb and the heat dissipating insulating material Rr. As shown in FIG. 9, when attention is paid to the surface temperature of the coil 2, in this embodiment, it is about 120 [° C.], in the comparative example is about 150 [° C.], and in this embodiment, 30 [° C.] relative to the comparative example. An improvement effect that decreases to a certain extent is observed. Further, when attention is paid to the surface temperature of the package 4, an improvement effect of about 75 [° C.] in the present embodiment and about 85 [° C.] in the comparative example and about 10 [° C.] in the present embodiment is recognized. Thus, the large current inductor 1 according to the present embodiment has good thermal conductivity and thermal radiation.

Therefore, according to such a large current inductor 1 according to the present embodiment, one or two or more coils 2 wound with a vertical rectangular conductive wire, a core 3 loaded in the coil 2, and the core 3 are The package 2 is provided with a package 4 formed of a thermally conductive material and containing the loaded coil 2, and the package 4 is filled with the thermally conductive material Ri as the potting material 5, so that the coil 2 (core 3) In addition, it is possible to further improve the heat conduction performance between the package 4 and the protection performance for the coil 2 and the durability of the large current inductor 1. Further, a part or all of one or more surfaces of the coil 2, the core 3 and the package 4 are coated with a heat-dissipating insulating material Rc as a coating agent 6, and the heat-dissipating insulating material Rc is applied to a silicone resin binder. In addition, a dispersant selected in the range of 0.01 to 50 [wt%] is blended with respect to 100 [wt%] of the silicone resin binder, and 100 to 600 with respect to 100 [wt%] of the silicone resin binder. The thermally conductive filler selected in the range of [wt%] and the particle size in the range of 0.1 to 20 [μm] is uniformly dispersed, at least the dielectric breakdown strength is 14 [kV / mm] or more, and Since the composition has a viscosity of 0.05 to 3 [Pa · s], the coil 2, the core 3 and the package 4 are coated with a heat-dissipating insulating material Rc having a predetermined thickness. It is possible to provide a coating layer can be easily and reliably coil 2, increase the core 3 and the package 4 itself thermal conductivity and heat dissipation.

Next, examples of the thermally conductive material Ri according to the modified embodiment of the present invention will be described with reference to FIGS.

In particular, the thermally conductive material Ri according to the modified embodiment is obtained by changing the thermally conductive filler. That is, in the above-described embodiment (basic embodiment), an example in which a single material of magnesium oxide is used as the thermally conductive filler has been shown. However, in the modified embodiment, aluminum oxide (alumina) and magnesium oxide (magnesia) are used. And three samples X, Y, and Z were used. Table 2 shows the mixing ratio of alumina and magnesia in each sample X, Y, and Z.

On the other hand, FIG. 10 shows the change characteristics of the thermal conductivity [W / (m · K)] with respect to the blending ratio [%] of each sample X, Y, Z (thermal conductive filler) with respect to the thermosetting resin binder. . As is apparent from FIG. 10, the thermal conductivity tends to increase as the mixing ratio of alumina with respect to magnesia is increased. That is, the thermal conductivity increases in the order of samples X, Y, and Z. Further, when the mixing ratio of magnesia and alumina is constant, the thermal conductivity tends to increase as the mixing ratio of each sample X, Y, Z with respect to the thermosetting resin binder increases.

The heat conductive material Ri according to the modified embodiment is the same as that of the basic embodiment described above except that the heat conductive filler is changed. That is, an epoxy resin (epoxy resin + curing agent) is used as a thermosetting resin binder, and a dispersing agent selected within a range of 1 to 180 [wt%] with respect to 100 [wt%] of the thermosetting resin binder. Furthermore, the thermal conductivity is selected in the range of 350 to 2000 [wt%] and the particle size in the range of 0.1 to 100 [μm] with respect to 100 [wt%] of the thermosetting resin binder. Use a filler. The particle size of the heat conductive filler is mixed with a large filler of about 5 to 100 [μm], a medium filler of about 0.5 to 20 [μm], and a small filler of about 0.1 to 10 [μm]. In Table 3, each raw material and compounding ratio which are used by modified embodiment (Example) are shown.

Therefore, the manufacturing method of the thermally conductive material Ri according to the modified embodiment is basically the same as that of the basic embodiment described above, and FIG. 11 is a part of the manufacturing process diagram shown in FIG. As shown in the manufacturing process diagram, steps 3 and 8 may be changed from “magnesium oxide particles” to “alumina particles + magnesia particles”. The other steps are the same as the manufacturing process diagram shown in FIG.

12 to 14 show various characteristics of the thermally conductive material Ri according to the manufactured modified embodiment, FIG. 12 is a temperature vs. viscosity characteristic diagram of the thermally conductive material Ri, and FIG. 13 is an evaluation of the thermally conductive material Ri. FIG. 14 is a test result table, and FIG. 14 is a graph showing a rise in temperature with respect to operating time when the heat conductive material Ri is used for a large current inductor.

Two examples OP1 and OP2 were used as the thermally conductive material Ri. Example OP1 uses Sample Y as the thermally conductive filler, and the filler blending ratio with respect to the thermosetting resin binder is 91.2 wt%. Example OP2 uses Sample Z as the thermally conductive filler. And the filler compounding ratio with respect to the thermosetting resin binder is 93.3 [wt%]. Moreover, as a comparative example, three typical commercial products TR1, TR2 and TR3 were used.

In the evaluation test (FIG. 13), workability is evaluated by viscosity and defoaming property, thermal characteristics are evaluated by thermal conductivity, glass transition temperature and thermal shock resistance, and electrical characteristics are volume resistance. The rate and dielectric breakdown strength were evaluated. In this case, the evaluation of the defoaming property is based on the time taken for the bubbles to escape depending on the conditions of pressure 50 [hPa] and temperature 70 [° C.] after potting 25 [milliliter] of the heat conductive material Ri on the package 4. It was. The glass transition temperature was 150 [° C.] or higher, and the heat resistance was evaluated. Thermal shock resistance was evaluated by potting plate materials (silicone rubber, Cu, Fe, Al, alumite, aramid paper) having different thermal expansion coefficients together with the heat conductive material Ri and heating to 150 [° C.] The thermal shock treatment in 3 [° C.] water was repeated 5 times. And the presence or absence of peeling and a crack was confirmed by observing the interface state of heat conductive material Ri and board | plate material, and it evaluated as "(circle)" when there was no peeling and a crack, and "x". The dielectric breakdown strength was evaluated at 10 [kHz] close to the frequency used as the in-vehicle inductor, and the breaking current was 10 [mA].

In the characteristics (evaluation) of the thermally conductive material Ri according to the modified embodiment, as shown in FIG. 12, Example OP1 has a viscosity of 25 [° C.] as very low as 58 [Pa · s] and is sufficient even at room temperature. In addition to exhibiting good viscosity characteristics such as being capable of casting, the defoaming property was 6.5 [min], and good workability was obtained. The thermal conductivity was 6.2 [W / (m · K)], showing a high value, and the thermal shock resistance was “◯” for all plate materials. Furthermore, the temperature rise characteristic with respect to the operating time when the thermally conductive material Ri of Example OP1 was used for a large current inductor is as shown in FIG. 14, and good results were obtained even for the commercial product TR2. . In FIG. 14, OP1c is the surface temperature of the coil 2 when using the embodiment PO1, TR2c is the surface temperature of the coil 2 when using the commercially available product TR2, and OP1b is the core 3 when using the embodiment PO1. , TR2b is the surface temperature of the core 3 when using the commercially available product TR2, OP1p is the surface temperature of the package 4 when using the embodiment PO1, and TR2p is the surface of the package 4 when using the commercially available product TR2. Each temperature is indicated. Thus, Example OP1 is particularly suitable for applications that require a balance between thermal conductivity and workability.

On the other hand, Example OP2 has a high viscosity of 25 [° C.], but when heated to 60 [° C.], the viscosity decreased to 56 [Pa · s], and casting was possible. Moreover, although defoaming property became longer than Example OP1, defoaming was completed in 30 [min]. Although Example OP2 is inferior to Example OP1 in terms of workability, the thermal conductivity is 8.8 [W / (m · K)], showing a very high value and thermal shock resistance. Also became “○” for all plate materials. Therefore, Example OP2 is particularly suitable for applications that require high thermal conductivity.

On the other hand, commercial products TR1, TR2 and TR3 are all difficult to defoam. Further, the thermal conductivity was 5.0 [W / (m · K)] or less, and both were inferior to Examples OP1 and OP2.

As described above, the best embodiment and the modified embodiment have been described in detail. However, the present invention is not limited to each of such embodiments, and the detailed configuration, shape, material (material), quantity, numerical value, and method are described. In this manner, any change, addition, or deletion can be made without departing from the spirit of the present invention.

For example, although an epoxy resin is exemplified as the thermosetting resin binder, it can be selected from various epoxy resins and used, and a silicone resin binder can also be selected from various silicone resins. Moreover, although the case where the thermosetting resin binder which consists of a main ingredient and a hardening | curing agent, ie, the heat-curable epoxy resin of two-component mixing, was used was illustrated, of course, one-component type epoxy resin (thermosetting resin binder) It may be. On the other hand, the coil 2, the core 3, and the package 4 are not limited to the illustrated materials, and can be implemented by other various materials. In particular, the coil 2 is preferably a copper material, but may be another material such as an aluminum material. The coil 2 is preferably manufactured using the coil pattern plate As, but does not exclude other manufacturing methods. Further, the core 3 can be a sintered type such as permalloy, nanocrystalline alloy, ferrite, Fe—Al—Si alloy, pure iron, or the like. In the embodiment, the large current inductor 1 using the pair of coil portions 21 and 22 is illustrated. However, for example, the package 4 is formed in a shape capable of accommodating a plurality of coils 2 (including the cores 3). However, it may be configured as an inductor 1 having a plurality of coils 2. Moreover, you may comprise as a transformer etc. which utilized a part of coil 2, or several coils 2 ....

The thermal conductive material Ri according to the present invention is optimal as a potting material for the exemplified large current inductor, but in addition, an electronic component (electrical component) including at least a substrate, a power source, a circuit, etc. that require thermal conductivity. In addition to the potting material, it can be used for various purposes such as a coating agent. Therefore, the heat conductive material Ri can be potted or coated by various methods such as spin coating, roll coating, spray coating, dip coating, spray coating, printing, and ink jet. Moreover, the inductor 1 for large currents according to the present invention can be used for various coil products.

Claims (17)

1. In a heat conductive material in which a heat conductive filler is mixed with a thermosetting resin binder, the thermosetting resin binder includes 1 to 180 [wt%] with respect to 100 [wt%] of the thermosetting resin binder. In addition to blending the dispersant selected in the range, the particle size is 0.1 to 100 [μm] in the range of 350 to 2000 [wt%] with respect to 100 [wt%] of the thermosetting resin binder. The heat conductive filler selected in the range is uniformly dispersed, at least 0.2 to 100 [Pa] when the thermal conductivity is 3.5 [W / (m · K)] or more and the viscosity is 60 [° C.] or less. A heat conductive material having a composition of s].
2. 2. The heat conductive material according to claim 1, wherein the thermosetting resin binder includes at least an epoxy resin having a viscosity selected within a range of 0.01 to 1 [Pa · s].
3. The heat conductive material according to claim 1 or 2, wherein the heat conductive filler has electrical insulation.
4. The heat conductive filler includes a single material or a composite material using at least one of magnesium oxide, aluminum oxide, silicon oxide, aluminum nitride, and boron nitride. The heat conductive material according to 1, 2 or 3.
5. The heat conductive material according to any one of claims 1 to 4, wherein the heat conductive filler includes a single particle size or a plurality of different particle sizes.
6. In the method for producing a thermally conductive material, which is produced by blending a thermally curable resin binder with a thermally conductive filler, the thermosetting resin binder contains 1 to 1 wt% relative to 100 wt% of the thermosetting resin binder. A dispersant selected in the range of 180 [wt%] is blended, and the particle diameter is 0.1 to 350 [wt%] with respect to 100 [wt%] of the thermosetting resin binder. The heat conductive filler selected in the range of up to 100 [μm] is mixed and stirred to uniformly disperse the heat conductive filler, and at least the heat conductivity is 3.5 [W / (m · K)] or more. And producing a composition having a viscosity of 0.2 to 100 [Pa · s] at a temperature of 60 ° C. or lower.
7. 7. The method for producing a heat conductive material according to claim 6, wherein the thermosetting resin binder includes at least an epoxy resin having a viscosity selected in a range of 0.01 to 1 [Pa · s]. .
8. The method for producing a thermally conductive material according to claim 6, wherein the thermosetting resin binder includes a resin binder using one liquid.
9. The method for producing a thermally conductive material according to claim 6, wherein the thermosetting resin binder includes a resin binder using at least two liquids including a main agent and a curing agent.
10. The heat conductive filler includes a single material or a composite material using at least one of magnesium oxide, aluminum oxide, silicon oxide, aluminum nitride, and boron nitride. 6. A method for producing a thermally conductive material according to 6.
11. Inductor for large current comprising one or two or more coils wound with a vertical rectangular conductive wire, a core to be loaded on the coil, and a package containing the coil loaded with the core and formed of a heat conductive material In the thermosetting resin binder, a dispersing agent selected in the range of 1 to 180 [wt%] is blended with the thermosetting resin binder 100 [wt%], and the thermosetting resin binder 100 is mixed. With respect to [wt%], the thermally conductive filler selected in the range of 350 to 2000 [wt%] and the particle size in the range of 0.1 to 100 [μm] is uniformly dispersed, and at least the thermal conductivity A thermally conductive material having a composition of not less than 3.5 [W / (m · K)] and a viscosity of 0.2 to 100 [Pa · s] at a temperature of 60 [° C.] or less. Pottin High-current inductor, characterized by comprising filling a timber.
12. The inductor for high current according to claim 11, wherein the thermally conductive filler has electrical insulation.
13. The heat conductive filler includes a single material or a composite material using at least one of magnesium oxide, aluminum oxide, silicon oxide, aluminum nitride, and boron nitride. 11. The large current inductor according to 11.
14. The high-current inductor according to claim 13, wherein the thermally conductive filler includes a single particle size or a plurality of different particle sizes.
15. 12. The large current inductor according to claim 11, wherein a coil produced by sequentially folding a coil pattern plate continuously formed of a sheet material is used as the coil.
16. One part or all of one or more surfaces of the coil, the core, and the package have at least a resin binder of 0.01 to 50 wt% with respect to 100 wt% of the resin binder. In addition to blending the dispersant selected in the range, the particle size was selected in the range of 100 to 600 [wt%] and the particle size in the range of 0.1 to 20 [μm] with respect to 100 [wt%] of the resin binder. Thermally conductive filler is uniformly dispersed, at least with a dielectric breakdown strength of 14 [kV / mm] (however, 10 [kHz], breaking current 10 [mA]) and a viscosity of 0 or less at a temperature of 60 [° C.] or less. 11. The high-current inductor according to claim 10, wherein a heat-dissipating insulating material having a composition of .05 to 3 [Pa · s] is coated.
17. The high-current inductor according to claim 16, wherein the resin binder contains at least a silicone-based resin binder.

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