KR20170120466A - Method of manufacturing a coil-embedded inductor for a high-efficiency DC-DC converter, Coil-embedded inductor manufactured thereby and High-efficiency DC-DC converter - Google Patents

Abstract

The present invention relates to a method of manufacturing a coil-embedded type inductor having a desired inductance characteristic by regulating the amount of filling of a magnetic molding liquid and a specific permeability and a method of manufacturing a coil-buried type inductor having such a high efficiency and high- The present invention relates to an excellent DC-DC converter, comprising: preparing a magnetic molding liquid; locating and fixing a part of the coil in the case; injecting a magnetic molding liquid into the case to charge 70 to 90 vol% And forming a magnetic core by curing the magnetic molding liquid, and the magnetic permeability of the magnetic molding liquid is 20 to 40 mu m. The method for manufacturing a coil-embedded inductor for a high efficiency DC-DC converter .

Description

FIELD OF THE INVENTION The present invention relates to a method of manufacturing a coil-embedded inductor for a high efficiency DC-DC converter, a coil-embedded inductor manufactured using the same, and a high efficiency DC-DC converter manufactured thereby and High-efficiency DC-DC converter}

The present invention relates to a method of manufacturing a coil-embedded type inductor for a high-efficiency DC-DC converter, and more particularly, to a method of manufacturing a coil-buried type inductor having a desired inductance characteristic by adjusting a filling amount of a magnetic molding liquid and a non- And a DC-DC converter including the coil-embedded type inductor and having high efficiency and excellent in high temperature and large current characteristics. The present invention is particularly applicable to a 48V-12V DC-DC converter for eco-friendly electric vehicles.

In general, a DC-DC converter is an electronic circuit device that converts a DC voltage from a DC voltage of a certain voltage to a DC voltage of a different voltage, generates an AC having a large power capacity by using an oscillation circuit at a DC voltage of a certain voltage, To convert the AC voltage to another AC voltage, and rectify the AC voltage again to obtain a DC voltage of a different voltage.

DC-DC converters are used in many types of electrical products. In some cases, the charger of a notebook is composed of a rectifier circuit and a DC-DC converter. The rectifier circuit rectifies the AC current and converts it to DC, and by using the DC-DC converter to accurately control the voltage, do. Many DC-DC converters are also used in the notebook body. The DC-DC converter of the notebook body converts the voltage of the battery to the voltage required by the notebook electronic circuit. In the case of the photovoltaic power generation system, the DC-DC converter boosts the voltage of the solar cell of about 200 V to about 400 V and supplies the voltage to the inverter.

DC-DC converters are particularly used in eco-friendly electric vehicle systems, which can include motors, inverters, DC-DC converters, and lithium-ion batteries, where the DC- ) Can be used to convert the electrical energy of the battery to electrical energy of a low voltage (e.g., 12V) battery, or vice versa.

The circuitry of this DC-DC converter for an environmentally friendly electric vehicle can comprise resistors, inductors, capacitors, transistors and controllers, where the inductor must be capable of handling large currents (eg, 250 A) as a power inductor, , Excellent heat radiation characteristics, and low core loss. Conventionally, ferrite inductors have been widely used as such inductors. In the related art, Korean Patent No. 10-0732612 entitled " High Efficiency Step-down DC-DC Converter for Hybrid Electric Vehicles, DC converter for a DC-DC converter, comprising: a current-doubler circuit section; a main-switch circuit; a current-doubler circuit section; and a transformer, current ferrite core and an EE-shaped ferrite core as the core of the inductor included in the current-doubler circuit portion.

Korean Patent No. 10-0732612

The first problem that the ferrite inductor of the prior art 1 has a large core loss and thus lowers the efficiency of the DC-DC converter, the second problem that the ferrite inductor of the prior art 1 is inferior in high current characteristics, The third problem is that the ferrite inductor of the technology 1 is inferior in the characteristic stability at high temperature. The fourth problem that the ferrite inductor of the prior art 1 is inferior in impact resistance, and the ferrite inductor of the prior art 1 uses the assembly method, And to solve the fifth problem that it is complicated.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. There will be.

In order to solve the above problems, the present invention provides a method of manufacturing a coil-buried type inductor for a high-efficiency DC-DC converter in which a portion of a coil is embedded in a magnetic core, comprising the steps of: preparing a magnetic molding liquid; Placing the magnetic molding liquid in the case to fill 70 to 90 vol% of the case, and curing the magnetic molding liquid to form the magnetic core And the magnetic permeability of the magnetic molding liquid is 20 to 40 占 The present invention provides a method of manufacturing a coil-embedded type inductor for a high efficiency DC-DC converter.

According to an embodiment of the present invention, the step of preparing the magnetic molding liquid may include the steps of: preparing an organic vehicle by stirring the polymer resin and a solvent; and kneading the magnetic powder with the organic vehicle to prepare a magnetic molding liquid The method comprising the steps of:

According to an embodiment of the present invention, the step of forming the magnetic core may include curing the magnetic molding liquid in a vacuum atmosphere.

According to an embodiment of the present invention, the polymer resin includes at least one selected from the group consisting of an epoxy resin, an epoxy acrylate resin, an acrylic resin, a silicone resin, a phenoxy resin and a urethane resin can do.

According to an embodiment of the present invention, the magnetic powder may be selected from the group consisting of pure iron, carbonyl iron, iron-silicon alloy, iron-silicon-chromium alloy, -Si-Al alloy, permalloy, molybdenum permalloy, and an amorphous powder.

According to an embodiment of the present invention, the magnetic powder may be a mixture of two or more kinds of magnetic powders having different average particle diameters.

The present invention also provides a coil-embedded type inductor for a high-efficiency DC-DC converter.

The present invention also provides a high efficiency DC-DC converter including a coil-embedded inductor.

The first effect that the DC-DC converter using the coil-embedded type inductor is higher in efficiency than the DC-DC converter using the conventional ferrite inductor is that the inductance of the coil-buried type does not drop sharply in the large current region, The third effect that the coil-embedded type inductor exhibits relatively stable inductance characteristics even at a high temperature, and the third effect is that the high-temperature characteristic is excellent, the fourth effect that the case is excellent in impact resistance because the case can reduce external impact, The fifth effect that the manufacturing method of the coil-embedded inductor is simple, the sixth effect that the coil-buried type inductor can be easily enlarged and the coil-buried type inductor having various shapes can be manufactured according to the shape of the case, The seventh effect that the inductance characteristics can be ensured, the high-temperature sintering process, The eighth effect that the manufacturing cost can be reduced because the pressurizing step for increasing the density and the like are unnecessary, the ninth effect that there is no fear that the coating of the buried coil is deteriorated because the pressurizing step and the high temperature annealing step are not necessary, It is possible to omit the sintering process or the annealing process of the coil, and the productivity can be improved by simplifying the process. Further, since the high thermal conductive material is used as the material of the case, 11 effect.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the composition of the invention described in the claims.

1 is a perspective view showing an embodiment of a coil-embedded type inductor for a high-efficiency DC-DC converter according to the present invention, except for a magnetic core.
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a coil-buried type inductor for a high efficiency DC-DC converter.
3 is a graph showing the results of evaluating the efficiency of the DC-DC converter in Experimental Example 5. FIG.
4 is a graph showing the results of evaluating high-temperature and high-current characteristics of a coil-embedded inductor in Experimental Example 6. FIG.
5 is a graph showing high temperature and large current characteristics of a conventional ferrite inductor of the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" (connected, connected, coupled) with another part, it is not only the case where it is "directly connected" "Is included. Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

A coil-embedded inductor 10 (hereinafter, referred to as a coil-embedded inductor 10) for a high-efficiency DC-DC converter of the present invention includes a coil 11, a magnetic core 12, 1 (except for the magnetic core 12), and FIG. 2 is a perspective view showing an example of such a coil-embedded inductor 10. As shown in FIG. 1 and 2, the coil-embedded inductor 10 has a structure in which a part of the coil 11 is buried in the magnetic core 12. As shown in Fig. A manufacturing method of the coil-embedded inductor 10 having such a structure will be described below in each step.

(I) Prepare a magnetic molding solution. The step (I) can be performed, for example, through the following detailed steps, which does not necessarily mean that it is necessary to proceed to these detailed steps.

(I-1) Polymer resin and solvent are stirred to prepare an organic vehicle. The polymer resin may be at least one polymer resin selected from the group consisting of an epoxy resin, an epoxy acrylate resin, an acrylic resin, a silicone resin, a phenoxy resin and a urethane resin, but is not limited thereto. The polymer resin functions as a binder with respect to the magnetic powder. This function is a function of a structural member that maintains the shape of the magnetic core 12, a function of providing chemical resistance to various organic solvents, The additive is bonded and supported to maintain a desired shape and a space between the magnetic powder is filled to increase the insulation of the magnetic core 12 and increase the specific resistance of the magnetic core 12, But is not limited to, the ability to reduce the eddy current loss of the device. The solvent is selected from the group consisting of methyl cellosolve, ethyl cellosolve, butyl cellosolve, butyl cellosolve acetate, aliphatic alcohol, terpineol terpineol, dihydro-terpineol, ethylene glycol, ethyl carbitol, butyl carbitol, butyl carbitol acetate, texanol, but are not limited to, at least one selected from the group consisting of terephthalic acid, terephthalic acid, texanol, methyl ethyl ketone, ethyl acetate and cyclohexanone. 50 to 60 wt% of a polymer resin and 40 to 50 wt% of a solvent are proposed in the composition ratio of the polymer resin and the solvent. When the polymer resin is less than 50 wt% or the solvent is more than 50 wt%, the binding function of the polymer resin deteriorates, so that the magnetic powder partially detaches after the magnetic molding liquid cures or a partial crack is generated in the magnetic core 12. [ And the polymer resin is more than 60 wt% or the solvent is less than 50 wt%, the amount of the polymer resin is excessively large, so that the magnetic flux density of the inductor 10 The magnetic molding liquid can flow out of the case 13.

Also, the components of the organic vehicle can affect the curing density of the magnetic molding liquid. In the organic vehicle, as the proportion of the high density material increases, the curing density of the magnetic molding liquid also increases, and the ratio The curing density of the magnetic molding liquid is also decreased.

The organic vehicle may comprise at least one additive selected from the group consisting of dispersants, stabilizers, catalysts and catalyst activators. In the case where the polymer resin is not uniformly distributed in the solvent and there is a possibility of aggregation, it is possible to prevent such agglomeration by injecting a dispersant, and when it is necessary to suppress the chemical change or the state change of the organic vehicle, If the mixing of the polymer resin and the solvent is not smooth, the reaction can be promoted with a catalyst or a catalytically active agent.

The preparation of the organic vehicle by stirring the polymer resin and the solvent (including additive when the additive is added) can be carried out for a fixed time under a given rpm condition using a mechanical stirrer. There is no upper limit in the agitation time, but it is necessary to keep in mind the minimum time for ensuring uniform agitation because it depends on the type of polymer resin, the type of solvent, the polymer resin and the solvent composition, It should be determined in some cases. After stirring, the produced organic vehicle may be further subjected to a process of filtering out impurities using a sieve and defoaming it. The defoaming will be described in detail later.

(I-2) The magnetic powder is kneaded with an organic vehicle to prepare a magnetic molding liquid. The magnetic powder and the organic vehicle are kneaded by weighing the magnetic powder and the organic vehicle, and the mixture is kneaded for a predetermined time so that the magnetic powder and the organic vehicle are evenly mixed. There is no upper limit in the time required for the kneading process, but it is necessary to keep in mind the minimum time for ensuring uniform kneading, because the type of magnetic powder, the composition and composition of the organic vehicle, the magnetic powder and the organic vehicle It depends on the composition, so it should be decided according to each case.

The magnetic powder may be selected from the group consisting of pure iron, carbonyl iron, Fe-Si alloy, Fe-Si-Cr alloy, Fe-Si-Al alloy, permalloy, But are not limited to, at least one selected from the group consisting of molybdenum permalloy (Mo-permalloy) and amorphous powder.

The average particle diameter of the magnetic powder is 10 to 150 mu m. When the average particle diameter of the magnetic powder is more than 150 mu m, the charging rate of the magnetic powder may be lowered and the curing density may be lowered. When the magnetic molding liquid is injected into the case 13, the nozzle of the dispenser is clogged Problems can arise. If the average particle diameter of the magnetic powder is less than 10 占 퐉, the eddy current loss of the magnetic core 12 may become a problem and the magnetic core may not sufficiently fill the gap between the magnetic powder 12 may have a problem in strength.

The magnetic powder may be constituted by mixing two or more kinds of magnetic powders having different average particle diameters. In this case, the magnetic powder having a small average particle diameter is located between the magnetic powders having a large average particle diameter, and as a result, the hardening density of the magnetic molding liquid can be increased. The curing density of the magnetic molding liquid will be described later. With respect to the mixing of two or more magnetic powders having different average particle diameters, the first magnetic powder having an average particle diameter of 2 to 5 m, the second magnetic powder having an average particle diameter of 10 to 20 m and the third magnetic powder having an average particle diameter of 50 to 150 m Magnetic powder is mixed. This is because a magnetic powder having a small average particle diameter can be located between the magnetic powders having an average particle diameter.

The magnetic molding liquid is preferably composed of 94 to 98 wt% of the magnetic powder and 2 to 6 wt% of the organic vehicle. When the magnetic powder is more than 98 wt% or the organic vehicle is less than 2 wt%, the amount of the magnetic powder is excessive, so that the production of the magnetic molding liquid by filling the magnetic powder may become impossible, The fluidity of the magnetic molding liquid is low on the side of the rheology when the magnetic molding liquid is injected into the case 13, so that a partial crack may occur in the magnetic core 12, and the binding of the polymer resin the magnetic powder may partially fall off after the magnetic molding liquid curing, and the eddy current loss may be increased in the magnetic core 12. When the magnetic powder is less than 94 wt% or the organic vehicle is more than 6 wt%, there is an advantage in terms of rheology, but since the amount of the organic vehicle is excessive and the charging amount of the magnetic powder is decreased, The inductance characteristic of the coil-embedded inductor 10 may be deteriorated due to the low specific magnetic permeability of the magnetoresistive element 12, and the amount of the polymer resin may be excessive, causing the magnetic molding liquid to flow out of the case 13 in accordance with the polymer swelling upon curing of the magnetic molding liquid .

The magnetic permeability of the magnetic molding liquid prepared by the composition ratio is preferably 20 to 40 mu m. When the specific permeability of the magnetic molding liquid is less than 20 mu m, the inductance characteristic of the coil-embedded inductor 10 is judged to be too low. When the magnetic permeability of the magnetic molding liquid exceeds 40 mu, It is judged that the overlapping property is too low. It is more preferable that the magnetic permeability of the magnetic molding liquid is 25 to 35 mu, because the coil-embedded inductor 10 of the present invention can be used as an inductor of 4 to 10 mu H included in the 48V to 12V DC-DC converter of the eco- And the specific permeability that can be obtained when the magnetic molding liquid is produced at the above composition ratio. However, when designing the coil-embedded inductor 10, it is desirable that the coil-embedded inductor 10 be designed to have an inductance characteristic of 5 to 20 μH at the initial 0A condition in connection with the inductor of 4 to 10 μH. Since the inductor 10 exhibits a characteristic in which the inductance gradually decreases as the current increases due to the soft magnetic powder contained in the magnetic core 12, a desired inductance characteristic is secured in the full current region including the maximum current It is necessary to set the inductance to be high at the initial 0A condition.

One of the performance requirements of the magnetic molding liquid is the curing density of the magnetic molding liquid. The curing density of the magnetic molding liquid is directly related to the composition ratio of the magnetic powder and the organic vehicle, and the density of the magnetic powder is larger than that of the organic vehicle Considering that the ratio of the magnetic powder increases, the density of the magnetic molding liquid increases, which means that the specific permeability of the magnetic molding liquid increases. Conversely, the smaller the ratio of the magnetic powder, the smaller the density of the magnetic molding liquid. This means that the specific permeability of the magnetic molding liquid becomes smaller, but also the eddy current loss is reduced. It is proposed that the density of the magnetic molding liquid is 5.5 to 6.5 g / cc in terms of the specific magnetic permeability and the eddy current loss. In this way, it is possible to secure a high magnetic permeability and at the same time to reduce the eddy current loss to some extent.

Before proceeding to the next step, a curing agent and / or a curing accelerator may be added to the magnetic molding liquid to accelerate the curing of the magnetic molding liquid. As the curing agent, aliphatic amines, modified aliphatic amines, aromatic amines, , Acid anhydrides, polyamides and imidazoles, and curing accelerators such as Lewis acids, alcohols, phenols, acylphenols, carboxylic acids, tertiary amines and imidazoles. Through the use of these, the time required for curing of the magnetic molding liquid can be reduced.

The magnetic molding liquid can also be defoamed before proceeding to the next step. The defoaming is to remove the bubbles contained in the magnetic molding liquid. The defoaming process can improve the inductance loss of the coil-embedded inductor 10. In addition, bubbles existing in the magnetic molding liquid can not only impair the impact resistance of the magnetic core 12 but also can induce cracks in the magnetic core 12 when moisture permeates into the bubbles Therefore, the defoaming process of the magnetic molding liquid is very important. In the method of defoaming the magnetic molding liquid, the magnetic molding liquid may be defoamed while rotating and revolving using a commercially available stirring / deaerator, but the method is not limited thereto.

(II) A part of the coil 11 is positioned and fixed inside the case 13. [ FIG. 1 shows a state in which a part of the coil 11 is fixed inside the case 13. As shown in FIG. Most of the coil 11 is embedded in the magnetic core 12, while the remaining part of the coil 11 is exposed to the outside of the magnetic core 12 to serve as an external terminal (electrode). Of course, it is possible to consider a configuration in which a part serving as the external terminal is provided as a separate member, and this member is electrically connected to the coil 11, but in the example of FIG. 1, a separate member And the coil 11 directly serves as an electrode.

(III) a magnetic molding liquid is injected into the case 13. [ The method of injecting the magnetic molding liquid into the case 13 may be injection using a pump and a tube or injection using a dispenser, but other methods are not excluded.

The amount of the magnetic molding liquid injected into the case 13 to fill the case 13 is preferably 70 to 90 vol% based on the volume of the case 13. When the amount of the magnetic molding liquid filling the case 13 is less than 70 vol% of the case 13, the magnetic field is insufficient and the magnetic path is not sufficiently secured. Therefore, the inductance characteristic of the coil- And the amount of the magnetic molding liquid filling the case 13 exceeds 90 vol% of the case 13, the inductance characteristic can be ensured more than in the case of 70 vol% The magnetic molding liquid may flow out of the case 13 in accordance with the swelling of the polymer during the curing process of the magnetic molding liquid.

The material of the case 13 may comprise high thermal conductive engineering plastics. This is because the case 13 needs to emit heat generated from the coil 11 and the magnetic core 12 and also to be insulative. The high thermal conductivity engineering plastic may be at least one selected from the group consisting of acrylonitrile butadiene styrene copolymer (ABS), polycarbonate (PC) and nylon, no. In addition, in order to enhance the thermal conductivity of the case 13, a thermally conductive filler may be added to the high thermal conductive engineering plastic to manufacture the case 13. The thermally conductive filler may be at least one selected from the group consisting of beryllium oxide (BeO), silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zinc oxide (ZnO) and boron nitride (BN) But is not limited thereto.

(IV) The magnetic molding liquid is cured to form the magnetic core 12. The method of curing the magnetic molding liquid is preferably, but not limited to, vacuum curing in which the magnetic molding liquid is cured in a vacuum atmosphere. When the magnetic molding liquid is vacuum-cured, the air bubbles inside the magnetic molding liquid can be removed. If the temperature and the curing time are appropriately set and vacuum-cured, all the bubbles in the magnetic molding liquid can be removed. Hereinafter, embodiments according to the present invention will be described in detail.

[Example 1 - Preparation of coil-embedded inductor 10 having inductance 4.5 占]]

(Epoxy resin, iron-silicon-chromium alloy powder, sandstroke powder, and other magnetic powder (the above-mentioned powder of iron-silicon-chromium alloy having an inductivity of 25 mu m) for the purpose of producing a coil- At least one selected from possible magnetic powders) were prepared. A square coil of 4.0 mm (width) x 1.6 mm (thickness) having a winding number of 6 was prepared and fixed inside the case 13 (the external terminal was exposed to the outside of the case 13). Next, the magnetic molding liquid was injected into the case 13 to fill 70 to 90 vol% of the case 13. Next, the case 13 was charged into a vacuum oven and the magnetic molding liquid was vacuum-cured. As a result, a coil-embedded inductor 10 having a magnetic core 12 of 26 mm (length) x 19 mm (width) x 27 mm (height) was manufactured.

[Comparative Example 1 - Charging of less than 70 vol% of case (13)] [

The same procedure as in Example 1 was carried out except that the amount of the magnetic molding liquid filling the case 13 was less than 70 vol% of the case 13.

[Comparative Example 2 - charging exceeding 90 vol% of the case (13)] [

The same procedure as in Example 1 was carried out except that the amount of the magnetic molding liquid filling the case 13 exceeded 90 vol% of the case 13.

[Comparative Example 3 - Specific permeability of magnetic molding liquid was less than 20 mu]

The same procedure as in Example 1 was carried out except that the magnetic permeability of the magnetic molding liquid was 18 占 퐉.

[Experimental Example 1 - Inductance Measurement]

The inductances of the coil-embedded inductors 10 manufactured in Example 1 and Comparative Examples 1 to 3 were measured using an oscilloscope (Agilent 54621A), and the results are shown in Table 1 below.

As can be seen from the above Table 1, when the amount of the magnetic molding liquid filling the case 13 is less than 70 vol% of the case 13, the inductance is 2.8 μH, When the amount of the magnetic molding liquid filling the case 13 exceeds 90 vol% of the case 13, the inductance is 4.5 H, but when the vacuum is cured, the magnetic molding liquid flows out of the case 13 When the magnetic permeability of the magnetic molding liquid was 18 mu, the inductance was 3.5 mu H, and the target inductance characteristics could not be secured. On the other hand, in the case where the amount of the magnetic molding liquid filling the case 13 is 70 to 90 vol% and the specific permeability of the magnetic molding liquid is 25 mu, the inductance characteristic of the inductance is 4.5 mu H, Respectively.

Example 2 - Fabrication of coil-embedded type inductor 10 having inductance 4.5 占].

(Epoxy resin, iron-silicon-chromium alloy powder, sandstroke powder and other magnetic powders (having a dielectric constant of 35 mu m or less) having a specific permeability of 35 mu for the purpose of manufacturing a coil-embedded inductor 10 having an inductance characteristic of 4.5 [ At least one selected from possible magnetic powders) were prepared. A square coil of 4.0 mm (width) × 1.6 mm (thickness) having a number of windings of 5 was prepared and fixed inside the case 13 (the external terminal was exposed to the outside of the case 13). Next, the magnetic molding liquid was injected into the case 13 to fill 70 to 90 vol% of the case 13. Next, the case 13 was charged into a vacuum oven and the magnetic molding liquid was vacuum-cured. As a result, a coil-embedded inductor 10 having a magnetic core 12 of 26 mm (length) x 19 mm (width) x 27 mm (height) was manufactured.

[Comparative Example 4 - charging of less than 70 vol% of case (13)] [

The same procedure as in Example 2 was carried out except that the amount of the magnetic molding liquid filling the case 13 was less than 70 vol% of the case 13.

[Comparative Example 5 - Charging exceeding 90 vol% of the case (13)] [

The same procedure as in Example 2 was carried out except that the amount of the magnetic molding liquid filling the case 13 exceeded 90 vol% of the case 13.

[Comparative Example 6-Specific magnetic permeability of magnetic molding liquid was less than 20 mu]

The same procedure as in Example 2 was carried out except that the magnetic permeability of the magnetic molding liquid was 18 mu.

[Experimental Example 2 - Measurement of inductance]

The inductances of the coil-embedded inductors 10 manufactured in Example 2 and Comparative Examples 4 to 6 were measured using an oscilloscope (Agilent 54621A), and the results are shown in Table 2 below.

As can be seen from the above Table 2, when the amount of the magnetic molding liquid filling the case 13 is less than 70 vol% of the case 13, the inductance is 3.0 μH, When the amount of the magnetic molding liquid filling the case 13 exceeds 90 vol% of the case 13, the inductance is 4.6 μH, but when the vacuum curing is performed, the magnetic molding liquid flows out of the case 13 When the magnetic permeability of the magnetic molding liquid was 18 mu, the inductance was 3.6 mu H and the target inductance characteristic could not be secured. On the other hand, when the amount of the magnetic molding liquid filling the case 13 is 70 to 90 vol% and the specific permeability of the magnetic molding liquid is 35 mu, the inductance of 4.5 mu H can be secured to achieve the target inductance characteristic Respectively.

[Example 3 - Fabrication of coil-embedded type inductor 10 having inductance of 10.0 占]]

(Epoxy resin, iron-silicon-chromium alloy powder, sandstock powder, and other magnetic powder (having a dielectric constant of 25 mu m or less) having a specific permeability of 25 mu m for the purpose of producing a coil-embedded inductor 10 having an inductance characteristic of 10.0 mu H At least one selected from possible magnetic powders) were prepared. A square coil of 3.5 mm (width) × 0.9 mm (thickness) having a winding number of 9 was prepared and fixed inside the case 13 (the external terminal was exposed to the outside of the case 13). Next, the magnetic molding liquid was injected into the case 13 to fill 70 to 90 vol% of the case 13. Next, the case 13 was charged into a vacuum oven and the magnetic molding liquid was vacuum-cured. As a result, a coil-embedded inductor 10 having a magnetic core 12 of 27 mm (length) x 17 mm (width) x 23 mm (height) was manufactured.

[Comparative Example 7 - charging of less than 70 vol% of case (13)] [

The same procedure as in Example 3 was carried out except that the amount of the magnetic molding liquid filling the case 13 was less than 70 vol% of the case 13.

[Comparative Example 8 - charging exceeding 90 vol% of the case (13)] [

The same procedure as in Example 3 was carried out except that the amount of the magnetic molding liquid filling the case 13 exceeded 90 vol% of the case 13.

[Comparative Example 9-Specific magnetic permeability of the magnetic molding liquid was less than 20 mu]

The same procedure as in Example 3 was carried out except that the magnetic permeability of the magnetic molding liquid was 18 mu m.

[Experimental Example 3 - Measurement of inductance]

The inductances of the coil-embedded inductors 10 manufactured in Example 3 and Comparative Examples 7 to 9 were measured using an oscilloscope (Agilent 54621A), and the results are shown in Table 3 below.

As can be seen from the above Table 3, when the amount of the magnetic molding liquid filling the case 13 is less than 70 vol% of the case 13, the inductance is 7.8 μH, When the amount of the magnetic molding liquid filling the case 13 exceeds 90 vol% of the case 13, the inductance is 10.2 μH, but when the vacuum curing is performed, the magnetic molding liquid flows out of the case 13 When the magnetic permeability of the magnetic molding liquid was 18 mu, the inductance was 8.1 mu H and the target inductance characteristics could not be secured. On the other hand, when the amount of the magnetic molding liquid filling the case 13 is 70 to 90 vol% and the specific permeability of the magnetic molding liquid is 25 mu m, the inductance of 10.4 mu H can be secured to achieve the target inductance characteristic Respectively.

[Embodiment 4 - Fabrication of coil-embedded inductor 10 having inductance of 10.0 占]]

(Epoxy resin, iron-silicon-chromium alloy powder, sandstroke powder and other magnetic powder (the above-mentioned powder of iron-silicon-chromium alloy powder having an inductivity of 35 mu) for the purpose of producing a coil- At least one selected from possible magnetic powders) were prepared. A square coil of 3.5 mm (width) × 0.9 mm (thickness) having a number of windings of 8 was prepared and fixed inside the case 13 (the external terminal was exposed to the outside of the case 13). Next, the magnetic molding liquid was injected into the case 13 to fill 70 to 90 vol% of the case 13. Next, the case 13 was charged into a vacuum oven and the magnetic molding liquid was vacuum-cured. As a result, a coil-embedded inductor 10 having a magnetic core 12 of 27 mm (length) x 17 mm (width) x 23 mm (height) was manufactured.

Comparative Example 10 - Charging of less than 70 vol% of the case (13)

The same procedure as in Example 4 was carried out except that the amount of the magnetic molding liquid filling the case 13 was less than 70 vol% of the case 13.

[Comparative Example 11 - charging exceeding 90 vol% of the case (13)] [

The same procedure as in Example 4 was carried out except that the amount of the magnetic molding liquid filling the case 13 exceeded 90 vol% of the case 13.

[Comparative Example 12-Specific magnetic permeability of the magnetic molding liquid was less than 20 mu]

The same procedure as in Example 4 was carried out except that the magnetic permeability of the magnetic molding liquid was 18 mu m.

[Experimental Example 4 - Measurement of inductance]

The inductances of the coil-embedded inductors 10 manufactured in Example 4 and Comparative Examples 10 to 12 were measured using an oscilloscope (Agilent 54621A). The results are shown in Table 4 below.

As can be seen from the above Table 4, when the amount of the magnetic molding liquid filling the case 13 is less than 70 vol% of the case 13, the inductance is 8.0 μH, When the amount of the magnetic molding liquid filling the case 13 exceeds 90 vol% of the case 13, the inductance is 10.3 μH, but when the vacuum curing is performed, the magnetic molding liquid flows out of the case 13 When the magnetic permeability of the magnetic molding liquid was 18 mu, the inductance was 7.9 mu H and the target inductance characteristic could not be secured. On the other hand, when the amount of the magnetic molding liquid filling the case 13 is 70 to 90 vol% and the specific permeability of the magnetic molding liquid is 35 microns, the inductance can be secured to 10.7 μH to achieve the target inductance characteristic Respectively.

[Embodiment 5 - Fabrication of DC-DC converter including coil-embedded inductor 10]

A 48V-12V DC-DC converter including the coil-embedded inductor 10 manufactured in Example 4 was manufactured.

[Comparative Example 13 - Fabrication of DC-DC converter including ferrite inductor]

Except that the conventional ferrite inductor was used in place of the coil-embedded inductor 10, the same conditions as in Example 5 were used.

[Experimental Example 5 - Evaluation of efficiency of DC-DC converter]

The results of evaluating the efficiency of the 48V-12V DC-DC converter manufactured in Example 5 and Comparative Example 13 in the range of 10 to 180 A are shown in FIG. 3, and the results are shown in Table 5 (Example 5) and Table 6 Example 13).

In Table 5 and Table 6, the total loss is divided by the loss due to the inductor and the remaining loss. As can be seen from FIGS. 3, 5 and 6, the efficiency of the DC-DC converter was evaluated to be higher than that of the conventional ferrite inductor when the coil-embedded inductor 10 of the present invention was used. In particular, in the region of 40 to 80 A, the efficiency of the DC-DC converter using the coil-embedded inductor 10 was evaluated to be about 0.45% higher than that of the DC-DC converter using the ferrite inductor. As can be seen from Tables 5 and 6, the above difference in efficiency is because the loss of the coil-embedded inductor 10 is smaller than the loss of the ferrite inductor. In other words, it has been confirmed that a high efficiency and low loss DC-DC converter can be manufactured by using the coil-embedded inductor 10 of the present invention.

[Experimental Example 6 - Evaluation of high temperature and high current characteristics]

The results of evaluating the high-temperature and high-current characteristics of the coil-embedded inductor 10 manufactured in Example 4 are shown in FIG. 5 shows high temperature and large current characteristics of a conventional ferrite inductor of the prior art. 4 and 5, in the conventional ferrite inductor, the inductance rapidly decreases from a certain region when the external temperature rises or the current rises, whereas the coil-embedded inductor 10 of the present invention has an external temperature rise Or the inductance gradually decreases even when the current increases. That is, it is confirmed that the high temperature and large current characteristics of the coil-embedded inductor 10 of the present invention are stable.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it should be understood that various changes and modifications will be apparent to those skilled in the art. Obviously, the invention is not limited to the embodiments described above. Accordingly, the scope of protection of the present invention should be construed according to the following claims, and all technical ideas which fall within the scope of equivalence by alteration, substitution, substitution, and the like within the scope of the present invention, Range. In addition, it should be clarified that some configurations of the drawings are intended to explain the configuration more clearly and are provided in an exaggerated or reduced size than the actual configuration.

10: High Efficiency DC-DC Converter Coil-Induced Inductors
11: Coil
12: magnetic core
13: Case

Claims (8)

A method of manufacturing a coil-embedded inductor (10) for a high-efficiency DC-DC converter in which a part of a coil (11) is embedded in a magnetic core (12)
(I) preparing a magnetic molding liquid;
(II) locating and securing a portion of the coil (11) inside the case (13);
(III) injecting the magnetic molding liquid into the case 13 to fill 70 to 90 vol% of the case 13; And
(IV) curing the magnetic molding liquid in the step (III) to form the magnetic core 12;
, ≪ / RTI >
Wherein the magnetic permeability of the magnetic molding liquid in the step (I) is 20 to 40 占 퐉.
The method according to claim 1,
The step (I)
(I-1) preparing an organic vehicle by stirring a polymer resin and a solvent; And
(I-2) preparing a magnetic molding liquid by kneading a magnetic powder with the organic vehicle;
Wherein the inductance of the inductor is greater than the inductance of the inductor.
The method according to claim 1,
The step (IV)
Wherein the magnetic molding liquid in the step (III) is cured in a vacuum atmosphere. ≪ RTI ID = 0.0 > 11. < / RTI >
The method of claim 2,
The polymer resin includes at least one selected from the group consisting of an epoxy resin, an epoxy acrylate resin, an acrylic resin, a silicone resin, a phenoxy resin, and a urethane resin. Gt;
The method of claim 2,
The magnetic powder may be selected from the group consisting of pure iron, carbonyl iron, Fe-Si alloy, Fe-Si-Cr alloy, Fe-Si-Al alloy, permalloy, , Molybdenum permalloy (Mo-permalloy), and amorphous powder. The method for manufacturing a coil-embedded type inductor for a high-efficiency DC-DC converter includes:
The method of claim 2,
Wherein the magnetic powder is a mixture of two or more types of magnetic powders having different average particle diameters.
A coil-embedded inductor for a high-efficiency DC-DC converter produced by the method according to any one of claims 1 to 6.
A high efficiency DC-DC converter comprising the coil-embedded inductor (10) of claim 7.

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