JP2010218688A - Heat dissipating insulating material, manufacturing method thereof, and large current inductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide both good coating property and good heat conductivity (heat dissipation) in addition to improved heat conductivity and heat dissipation, for contribution to improved quality (uniform quality). <P>SOLUTION: A silicone resin binder 100 [wt.%] is blended with a dispersant selected in a range of 0.01-50 [wt.%] in the silicone resin binder. A heat conductive filler, which has a particle size of 100-600 [wt.%] and is selected in the range of 0.1-20 [μm], is uniformity dispersed in the silicone resin binder 100 [wt.%]. Thus such composition has a dielectric strength of 14 [kV/mm] (where, 10 [kHz], cut-off current of 10 [mA]) or higher, and a viscosity of 0.05-3 [Pa s]. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat dissipating insulating material in which a heat conductive filler is mixed with a thermosetting resin binder, a method for manufacturing the heat dissipating insulating material, and a large current inductor using the heat dissipating insulating 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 by filling with a potting material. Therefore, sufficient thermal conductivity and heat dissipation are required.

  For this reason, conventionally, there is also known a heat-dissipating insulating material for mixing heat-conductive filler in a binder to efficiently conduct and dissipate heat generated by electrical components. 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 size of 50 to 100 μm and an average particle size of 10 μm or less in a weight ratio of 1: A heat conductive sheet mixed in 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 dissipating insulating material in which the above-described binder is mixed with the heat conductive filler has the following problems.

  First, the usage and usage of heat-dissipating insulating materials tend to be specialized, such as interposing between the surface of an electronic component (electrical component) and a heat sink, so it can be applied to other electronic components. Hateful. In particular, when a component such as a coil, a core, and a package using a vertical rectangular conductor is combined like a large current inductor, the heat transfer path from the coil serving as a heat source to the outer surface of the package becomes complicated. When the unique structure is not taken into consideration, it is difficult to ensure sufficient thermal conductivity and heat dissipation even when used as a coating agent.

  Second, when used as a coating agent, the fluidity (viscosity) of the heat-dissipating insulating material is important, but when the thermally conductive filler is mixed with the binder at a high density and dispersed uniformly, the fluidity is high. Therefore, it becomes difficult to knead the binder and the heat conductive filler, and the heat conductivity of the filler cannot be ensured. Therefore, in order to ensure the thermal conductivity, it is necessary to increase the viscosity to some extent, and it is difficult to ensure a good coating property for a part having many minute gaps such as an inductor.

  An object of the present invention is to provide a heat dissipating insulating material, a method for manufacturing the same, and a high-current inductor that have solved the problems in the background art.

  In order to solve the above-described problem, the heat dissipating insulating material Rc according to the present invention is a heat dissipating insulating material obtained by mixing a thermosetting resin binder with a heat conductive filler. While blending a dispersant selected in the range of 0.01 to 50 [wt%] with respect to [wt%], 100 to 600 [wt%] with respect to 100 [wt%] of the silicone-based resin binder. The heat conductive filler having a particle diameter of 0.1 to 20 [μm] is uniformly dispersed, and at least the dielectric breakdown strength is 14 [kV / mm] (however, 10 [kHz], It is characterized by having a composition with a breaking current of 10 [mA]) or more and a viscosity of 0.05 to 3 [Pa · s].

  In addition, the manufacturing method of the heat dissipating insulating material Rc according to the present invention includes the step of mixing the thermosetting resin binder with the heat conductive filler to manufacture the heat dissipating insulating material Rc. A dispersant selected in the range of 0.01 to 50 [wt%] is blended with 100 [wt%] of the binder, and 100 to 600 [wt%] with respect to 100 [wt%] of the silicone resin binder. The heat conductive filler selected in the range of 0.1 to 20 [μm] is mixed and stirred to uniformly disperse the heat conductive filler. 14 [kV / mm] (however, 10 [kHz], breaking current 10 [mA]) or more, and a composition having a viscosity of 0.05 to 3 [Pa · s] is obtained. To.

  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 silicone resin binder is applied to a part or all of one or two or more surfaces 2f of the coil 2, the core 3, and the package 4, While blending the dispersant selected in the range of 0.01 to 50 wt% with respect to 100 wt% of the silicone resin binder, 100 to 100 wt% with respect to 100 wt% of the silicone resin binder. The thermally conductive filler selected in the range of 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 14 [kV]. mm] (however, 10 [kHz], breaking current 10 [mA]) or more, and a heat-radiating insulating material Rc having a viscosity of 0.05 to 3 [Pa · s] is coated as a coating agent 6. It is characterized by.

  On the other hand, according to the preferred embodiment of the present invention, the thermally conductive filler in the heat dissipating insulating material Rc can have electrical insulation. Therefore, the thermally conductive filler can contain at least a single material or a composite material using one or more of magnesium oxide, aluminum nitride, boron nitride, and a single particle size. Alternatively, multiple 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, in the package 4, the thermosetting resin binder is blended with a dispersant selected in the range of 1 to 180 [wt%] with respect to the thermosetting resin binder 100 [wt%], 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 uniformly dispersed Then, at least the heat conductive material Ri having a composition having a thermal conductivity of 3.5 [W / (m · K)] or more and a viscosity of 0.2 to 100 [Pa · s] is used as the potting material 5. It is desirable to fill as. At this time, an epoxy resin having a viscosity selected in the range of 0.01 to 1 [Pa · s] can be used as the thermosetting resin binder, and thermosetting used for the heat conductive material Ri. A main agent and a curing agent can be used for the resin binder.

  According to the heat dissipating insulating material Rc, the manufacturing method thereof, and the large current inductor 1 according to the present invention, the following remarkable effects are obtained.

  (1) The heat dissipating insulating material Rc blends a silicone resin binder with a dispersant selected in the range of 0.01 to 50 [wt%] with respect to 100 [wt%] of the silicone resin binder. The heat 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 with respect to 100 [wt%] of the silicone resin binder. 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 [Pa · s]. Even when used as a coating agent 6 in a complicated heat transfer path, sufficient thermal conductivity and heat dissipation can be obtained, and in particular, good coating properties and good thermal conductivity (heat dissipation) Both can be made compatible. Further, the uniform dispersion of the heat conductive filler can contribute to improving the quality (homogenization) of the heat dissipating insulating material Rc.

  (2) The high-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. A package 4 made of a thermally conductive material, and a part or all of one or more surfaces 2f 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. Therefore, the coil 2, the core 3 and the package 4 can be easily and reliably provided with a coating layer of the heat-radiating insulating material Rc having a predetermined thickness, and the coil 2, the core 3 and the package 4 themselves. The heat conductivity and heat dissipation can be further improved.

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

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

  (8) According to a preferred embodiment, the dispersing agent selected in the range of 1 to 180 [wt%] with respect to the thermosetting resin binder 100 [wt%] in the package 4 inside the package 4 In addition, the heat conduction was 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. Heat conductive material Ri having a composition in which the conductive filler is uniformly dispersed, the thermal conductivity is 3.5 [W / (m · K)] or more, and the viscosity is 0.2 to 100 [Pa · s]. Is filled as the potting material 5, even in the case of the large current inductor 1 having a large number of minute gaps, there is no possibility that unfilled gaps are generated, and the heat conduction efficiency and the heat dissipation efficiency are improved. Can be general purpose In addition, it can contribute to improving the quality (homogenization) of the thermally conductive material Ri. In particular, the heat conduction performance between the coil 2 (core 3) and the package 4 can be further enhanced, and the protection performance for the coil 2 and the durability of the high-current inductor 1 can be further enhanced.

  (9) According to a preferred embodiment, if at least an epoxy resin having a viscosity selected in the range of 0.01 to 1 [Pa · s] is used for the thermosetting resin binder in the heat conductive material Ri, the viscosity is low. Since the heat conductive filler is mixed with the epoxy resin, the uniform dispersion of the heat conductive filler can be further optimized.

  (10) If a thermosetting resin binder comprising a main agent and a curing agent is used as the thermosetting resin binder in the heat conductive material Ri according to a preferred embodiment, the reaction at the time of manufacturing the heat conductive material Ri will be described. The flexibility and handling can be made more flexible.

Manufacturing process diagram of heat-radiating insulating material according to a preferred embodiment of the present invention, The manufacturing process figure of the heat conductive material used for the inductor for large currents concerning the suitable 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, 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,

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

  First, the heat-radiating insulating material Rc and the manufacturing method thereof according to the present embodiment will be described with reference to the manufacturing process diagram shown in FIG. 1 and FIGS. 6 and 7.

  The heat dissipating insulating material Rc is basically composed of a silicone resin binder and a dispersant selected in a range of 0.01 to 50 [wt%] with respect to 100 [wt%] of the silicone resin binder. Thermally conductive filler selected in a range of 100 to 600 [wt%] and a particle size in the range of 0.1 to 20 [μm] with respect to the silicone resin binder 100 [wt%] is uniformly dispersed, and at least The dielectric breakdown strength is 14 [kV / mm] (however, 10 [kHz], breaking current 10 [mA]) or more, and the viscosity is 0.05 to 3 [Pa · s]. 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.

  As the silicone resin binder, a low-viscosity silicone resin having 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, but as an alternative to silicone resin, epoxy resin can be used when heat resistance is required, and urethane resin, phenol resin, melamine resin can be used when heat resistance is not required Urea resin, unsaturated polyester resin, alkyd resin, thermosetting polyimide resin, etc. can also be used.

  Various known dispersants and various known diluent solvents can be used as the dispersant and the diluent solvent, and are not limited to specific dispersants and diluent solvents. In this case, the dispersant is selected in the range of 0.01 to 50 [wt%] with respect to 100 [wt%] of the silicone resin binder, and the diluting solvent is used to adjust the viscosity. If an appropriate amount of a dispersant is added to the silicone resin, good dispersibility can be achieved even when a high-density thermal conductive filler is mixed with the silicone resin. The heat conductive filler can be made more uniform.

  As the thermally conductive filler, a single material of magnesium oxide and silicon oxide (silica) particles having high electrical insulation are used in combination. Magnesium oxide is excellent in cost merit, has high thermal conductivity, and also has electrical insulation. As for the magnesium oxide particles used as the heat conductive filler, it is desirable to select a particle size in a range of 0.1 to 20 [μm] and to include a plurality of different particle sizes in the particle size of the silica particles. In this embodiment (Example), a mixed material (composite material) of a medium filler of about 1 to 20 [μm] and a small filler of about 0.1 to 10 [μm] was used. Then, with respect to 100 [wt%] of the silicone resin, the entire magnesium oxide particles and silica particles are selected in the range of 100 to 600 [wt%], preferably around 195 [wt%]. Of course, as long as the particle diameter is in the range of 0.1 to 20 [μm], a single particle diameter may be used. In addition, instead of magnesium oxide particles, a single material of aluminum nitride particles or boron nitride particles may be used, or a composite material including two or more of magnesium oxide particles, aluminum nitride particles, and boron nitride particles is used. Also good. As described above, if a single material or a composite material including at least one of magnesium oxide, aluminum nitride, and boron nitride is used for the thermally conductive filler, good thermal conductivity and heat dissipation are ensured. From the viewpoint of achieving high performance, if a filler having a plurality of different particle sizes such as silica particles is selected, each filler can be uniformly dispersed with high density in the silicone resin as a binder. By mixing different particle diameters, it is possible to further optimize from the viewpoint of enhancing thermal conductivity (heat dissipation). In addition, various ceramic particles such as silicon nitride, titanium oxide, zirconium oxide, silicon oxide, tin oxide, zinc oxide, and silicon carbide that can ensure electrical insulation and thermal conductivity can be used as the thermally conductive filler. It is.

  Next, a specific manufacturing procedure will be described. First, the prepared dispersant, diluent solvent, magnesium oxide particles and silica particles are blended (mixed) with the prepared silicone resin binder (steps S1, S2, S3, S4 and S5). And it fully stirs with a stirring apparatus (process S6). At this time, beads having a specific gravity significantly different from that of the heat conductive filler may be added to the material to be stirred, and the magnesium oxide particles and silica particles may be uniformly dispersed using a stirring method capable of uniform dispersion such as planetary stirring. desirable. Further, the entire viscosity is adjusted to about 1 [Pa · s] by adding a suitable amount of a diluting solvent, and sufficient defoaming is performed by a defoaming device for bubbles generated during stirring (step S7). . As a result, a heat dissipating insulating material Rc having a high density structure in which magnesium oxide particles and silica particles are uniformly dispersed with respect to the silicone resin can be obtained, and this heat dissipating insulating material Rc is coated on the large current inductor 1 described later. It can be used as the agent 6 (step S8).

  Table 1 shows the characteristics (performance) of the heat-radiating insulating material Rc (Example) manufactured in this way. 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. 6 shows the heat-dissipating insulating material Rr (Example) obtained and the heating time of the heat-dissipating insulating material Rr using a polyamide-imide resin generally marketed as a heat-resistant insulating coating agent having the same use as a comparative example. H] (250 [° C.]) with respect to the mass reduction rate [%], and FIG. 7 shows the heating time of the obtained heat insulating material Rc (Example) and the heat insulating material Rr as a comparative example. The characteristic of dielectric breakdown strength [kV / mm] with respect to [H] (200 [° C.]) is shown. As is apparent from Table 1, FIG. 6 and FIG. 7, 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. Moreover, the mass reduction rate used as an evaluation of heat resistance is ensured within -3 [%] in 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]).

  As described above, the heat dissipating insulating material Rc according to this embodiment is a dispersant selected from 0.01 to 50 [wt%] with respect to the silicone resin binder 100 [wt%]. And a 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] with respect to 100 [wt%] of the silicone resin binder. A composition which is uniformly dispersed, has a dielectric breakdown strength of 14 [kV / mm] (however, 10 [kHz], breaking current 10 [mA]) or more and a viscosity of 0.05 to 3 [Pa · s]. Therefore, even when used as a coating agent 6 in a complicated heat transfer path, sufficient thermal conductivity and heat dissipation can be obtained, and in particular, good coating properties and good heat Electrical resistance can be compatible both (heat radiation). Further, the uniform dispersion of the heat conductive filler can contribute to improving the quality (homogenization) of the heat dissipating insulating material Rc.

  Next, a manufacturing method of the large current inductor 1 according to the present embodiment including the coating method of the coating agent 6 using the heat dissipating insulating material Rc will be described with reference to FIGS.

  When manufacturing the high-current inductor 1, first, the coil 2, the core 3, and the package 4, which are main components, are respectively 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, the above-described coating agent 6 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 surface 2f ... of the obtained coil 2 is coated with the coating agent 6 using the heat dissipating insulating material Rc. 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 S9). 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].

  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]. Thereby, the coil 2 which provided the coating layer which has the thickness of 60-80 [micrometer] 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 S10). In this case, basically, the coating process is performed so that the thickness of the coating layer is about 60 to 80 [μm], and thereafter the surface of the core 3 is coated. 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 the cover portion 4c are subjected to a coating process using the heat-radiating insulating material Rc (step S11). 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], and the coating is performed thereafter, as in the above-described coating process of the core dividing portion 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).

  When these coil 2, core 3 and package 4 are obtained, intermediate assembly is performed (step S12). 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. As a result, the intermediate assembly 1m of the high-current inductor 1 can be obtained (step 13). A potting material 5 using a heat conductive material Ri described below can be potted in the package 4 (case portion 4p) of the intermediate assembly 1m.

  Next, the heat conductive material Ri used as a potting material and the manufacturing method thereof will be described with reference to the manufacturing process diagram shown in FIG. 2 and FIG.

  This heat conductive material Ri also basically has the same composition as the heat-dissipating insulating material Rc described above, and the thermosetting resin binder is based on 100 [wt%] of the thermosetting resin binder. 1 to 180 [wt%], and a dispersant selected from the range of 350 to 2000 [wt%] with respect to the thermosetting resin binder 100 [wt%]. It has a composition in which the thermally conductive filler selected in the range of 0.1 to 100 [μm] is uniformly dispersed. Therefore, when manufacturing the heat conductive material Ri, a thermosetting resin binder, a dispersant, and a heat conductive filler are prepared as raw materials.

  As the thermosetting resin binder, an epoxy resin which is an organic material and has a relatively high heat resistance, particularly an epoxy resin composed of a main agent and a curing agent (a two-component mixed thermosetting type) is used. 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, a low-viscosity epoxy resin having a viscosity of 0.01 to 1 [Pa · s] is selected. 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. As the thermosetting resin binder, an epoxy resin is desirable. However, if heat resistance is required, a silicone resin can also be used. If heat resistance is not required, a urethane resin or phenolic resin can be used. Resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, thermosetting polyimide resins, and the like can also be used.

  A dispersing agent is selected in the range of 1 to 180 [wt%] with respect to 100 [wt%] of the main agent or the 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.

  A single material of magnesium oxide is used 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). Moreover, the magnesium oxide particle used as a heat conductive filler is selected in the range of 350-2000 [wt%] with respect to 100 [wt%] of the main agent or the curing agent. Furthermore, the particle size 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 sizes. In this embodiment (Example), 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] were mixed. . Of course, as long as the particle diameter is in the range of 0.1 to 100 [μm], a single particle diameter may be used. In addition, instead of magnesium oxide particles, a single material of aluminum nitride particles or boron nitride particles may be used, or a composite material including two or more of magnesium oxide particles, aluminum nitride particles, and boron nitride particles is used. Also good. As described above, if a single material or a composite material including at least one of magnesium oxide, aluminum nitride, and boron nitride is used for the thermally conductive filler, good thermal conductivity and heat dissipation are ensured. From the point of view, it is possible to obtain a larger performance, and if a filler having a plurality of different particle diameters is selected, different particles are used when uniformly dispersing each filler at a high density with respect to the main agent or curing agent as a binder. The mixture of diameters can be further optimized from the viewpoint of improving thermal conductivity (heat dissipation). In addition, various ceramic particles such as silicon nitride, titanium oxide, zirconium oxide, silicon oxide, tin oxide, zinc oxide, and silicon carbide that can ensure electrical insulation and thermal conductivity can be used as the thermally conductive filler. It is.

  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 S21 and S22). Next, the prepared magnesium oxide particles (thermally conductive filler) are mixed (steps S22 and S23). And the obtained mixed solution fully stirs with a stirring apparatus, and performs sufficient defoaming with a defoaming apparatus (process S24). 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 S25). Similarly, when manufacturing the curing agent solution, first, the prepared dispersant is blended with the prepared curing agent (epoxy resin) (steps S26 and S27). Next, the prepared magnesium oxide particles are mixed (steps S27 and S28). The obtained mixed solution is sufficiently stirred by a stirring device and sufficiently defoamed by a defoaming device (step S29). Thereby, the hardening | curing agent solution in which a high-density magnesium oxide particle is uniformly disperse | distributed with respect to an epoxy resin (hardening agent) can be obtained (process S30).

  Next, the obtained main agent solution and curing agent solution are mixed while being appropriately stirred (steps S25, S30, S31). Thereby, the target heat conductive material Ri whose whole viscosity will be 0.2-100 [Pa * s] can be obtained (process S12). The thermally conductive material Ri having a viscosity in the range of 0.2 to 100 [Pa · s] is optimal as the potting material 5 of the inductor 1 for large current, and in the thermally conductive material Ri according to the present embodiment, 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 mixing of the main agent solution and the curing agent solution is performed immediately before filling (injecting) the inside of a case portion 4 p described later as the potting material 5.

  In such a heat conductive material Ri, a dispersant selected in a range of 1 to 180 [wt%] with respect to the thermosetting resin binder 100 [wt%] is blended with 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] is uniform with respect to 100 [wt%] of the thermosetting resin binder. Since it has a composition that is dispersed and at least has a thermal conductivity of 3.5 [W / (m · K)] or more and a viscosity of 0.2 to 100 [Pa · s], for example, a component with many minute gaps In this case, there is no possibility that an unfilled gap is generated, and the heat conduction efficiency and the heat radiation efficiency can be improved, and the versatility can be improved. In addition, the quality of the heat conductive material Ri ( Homogenization) can also be improved.

  Then, the heat conductive material Ri is filled (injected) into the case portion 4p as the potting material 5 (step S34). Next, the potting material 5 is cured by heating at a temperature corresponding to the curing temperature of the epoxy resin used for the thermally conductive material Ri (step S35). At this time, sufficient defoaming is performed by a defoaming apparatus (step S36). When the curing process for the potting material 5 is completed, final assembly is performed (step S37). 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 manufacturing steps described above, the intended high current inductor 1 shown in FIG. 5 can be obtained (step S38).

  FIG. 8 shows the rising temperature characteristics of each part with respect to the operating time [minutes] when the obtained large current inductor 1 is energized. Tci is the surface temperature of the coil 2 in this embodiment (example), Tcr is the surface temperature of the coil 2 in the comparative example, Tbi is the surface temperature of the core 3 in the example, and Tbr is the surface temperature of the core 3 in the comparative example. Show. In this case, the example is the inductor 1 using the heat dissipating insulating material Rc, and the comparative example is the inductor using the heat dissipating insulating material Rr. As shown in FIG. 8, when attention is paid to the surface temperature of the coil 2, it is about 120 [° C.] in the example, about 150 [° C.] in the comparative example, and about 30 [° C.] lower than the comparative example in the example. Improvement effect 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 A package 4 that houses the loaded coil 2 and is formed of a thermally conductive material, and heat dissipation insulation is provided on part or all of one or more surfaces 2f of the coil 2, the core 3, and the package 4; Since the material Rc is coated as the coating agent 6, the coil 2, the core 3 and the package 4 can be provided with a coating layer of the heat-dissipating insulating material Rc having a predetermined thickness easily and reliably. The thermal conductivity and heat dissipation of the coil 2, the core 3 and the package 4 themselves can be further enhanced.

  The preferred embodiment has been described in detail above. However, the present invention is not limited to such an embodiment, and the gist of the present invention is described in detail configuration, shape, material, quantity, numerical value, method, and the like. Any change, addition, or deletion can be made without departing from the scope.

  For example, the silicone resin binder can be selected from various silicone resins, and the epoxy resin can be selected from various epoxy resins. Moreover, the coil 2, the core 3, and the package 4 are not limited to the illustrated material, 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. Furthermore, the core 3 can also use a sintered type such as permalloy, nanocrystalline alloy, ferrite, Fe—Al—Si alloy, or pure iron. 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 heat-dissipating insulating material Rc according to the present invention is optimal as a coating agent in the illustrated high-current inductor 1, but in addition, electronic components (electrical components) including at least a substrate, a power supply, a circuit, etc. that require thermal conductivity In addition to coating agents, it can be used for various purposes such as potting materials. Accordingly, the heat dissipating insulating material Rc can be coated or potted 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.

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

Claims (15)

  In the heat dissipating insulating material in which the heat conductive filler is mixed with the thermosetting resin binder, the silicone resin binder is in the range of 0.01 to 50 wt% with respect to the silicone resin binder 100 wt%. In addition to the blending of the dispersant selected in Step 1, the particle size is selected in the range of 100 to 600 [wt%] and in the range of 0.1 to 20 [μm] with respect to 100 [wt%] of the silicone resin binder. The thermally conductive filler 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 [Pa A heat dissipating insulating material having a composition of s].   The heat-radiating insulating material according to claim 1, wherein the thermally conductive filler has an electrical insulating property.   The heat dissipation filler according to claim 1 or 2, wherein the thermally conductive filler includes a single material or a composite material using at least one of magnesium oxide, aluminum nitride, and boron nitride. Insulating material.   The heat-radiating insulating material according to claim 1, wherein the thermally conductive filler includes a single particle size or a plurality of different particle sizes.   In the method for producing a heat-dissipating insulating material produced by mixing a thermosetting resin binder with a thermosetting resin binder, the silicone resin binder is used in an amount of 0.01 to 50 with respect to 100 [wt%] of the silicone resin binder. In addition to blending the dispersant selected in the range of [wt%], the particle size is in the range of 100 to 600 [wt%] and the particle size is 0.1 to 20 [wt%] with respect to 100 [wt%] of the silicone resin binder. The heat conductive filler selected in the range of μm] is mixed and stirred to uniformly disperse the heat conductive filler. At least the dielectric breakdown strength is 14 [kV / mm] (however, 10 [kHz], cut off) A method for producing a heat-dissipating insulating material, characterized in that a composition having a current of 10 [mA]) or more and a viscosity of 0.05 to 3 [Pa · s] is obtained.   The method for manufacturing a heat-dissipating insulating material according to claim 1, wherein the thermally conductive filler has an electrical insulating property.   The heat-radiating insulation according to claim 5, wherein the thermally conductive filler includes at least a single material or a composite material using one or more of magnesium oxide, aluminum nitride, and boron nitride. Material manufacturing method.   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 one or two or more surfaces of the coil, the core, and the package, the silicone resin binder may be 0.01 to 50 with respect to 100 wt% of the silicone resin binder. In addition to blending a [wt%] dispersant, the silicone resin binder 100 [wt%] is 100 to 600 [wt%] and the particle size is in the range of 0.1 to 20 [μm]. The selected heat conductive filler is uniformly dispersed, at least the dielectric breakdown strength is 14 [kV / mm] (however, 10 [kHz], breaking current 10 [mA]) or more, and the viscosity There large current inductor, characterized in that the heat radiation insulating material having a composition comprising 0.05 to 3 [Pa · s], made by coating a coating agent.   9. The large current inductor according to claim 8, wherein the thermally conductive filler has electrical insulation.   10. The large-sized material according to claim 8, wherein the thermally conductive filler includes a single material or a composite material using at least one of magnesium oxide, aluminum nitride, and boron nitride. Inductor for current.   The inductor for high current according to claim 8, 9 or 10, wherein the thermally conductive filler includes a single particle size or a plurality of different particle sizes.   The inductor for high current according to any one of claims 8 to 11, wherein a coil produced by sequentially folding a coil pattern plate continuously formed of a sheet material is used as the coil.   In the inside of the package, the thermosetting resin binder is blended with a dispersant selected in the range of 1 to 180 [wt%] with respect to the thermosetting resin binder 100 [wt%], and the thermosetting 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 with respect to 100 [wt%] of the conductive resin binder, A heat conductive material having a composition with a thermal conductivity of 3.5 [W / (m · K)] or more and a viscosity of 0.2 to 100 [Pa · s] is filled as a potting material. 9. The inductor for high current according to claim 8, wherein:   The high-current inductor according to claim 13, wherein the thermosetting resin binder includes at least an epoxy-based resin having a viscosity selected in a range of 0.01 to 1 [Pa · s].   The inductor for high current according to claim 13 or 14, wherein the thermosetting resin binder contains a main agent and a curing agent.

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