KR101640559B1 - A manufacturing method of magnetic powder paste for a molded inductor by molding under a room temperature condition and magnetic powder paste manufactured thereby. - Google Patents

Abstract

A method of manufacturing a magnetic powder paste for manufacturing a molded inductor, the method comprising the steps of: (i) taking into account the characteristics of the magnetic core and the workability of the paste, Uniformly stirring to produce an organic vehicle (s10); (ii) treating the magnetic powder with phosphoric acid to clean and polish the surface of the magnetic powder, and adding the phosphoric acid-treated magnetic powder to the organic vehicle (s20); (iii) a step (s30) of rolling mixing milling the magnetic powder and the organic vehicle, wherein the addition of the magnetic powder in the step (ii) 97 wt% of the organic vehicle and 3 wt% to 50 wt% of the organic vehicle.

Description

TECHNICAL FIELD The present invention relates to a method of manufacturing a magnetic powder paste for manufacturing a coil-embedded inductor at room temperature, and a magnetic powder paste for producing a magnetic powder paste for a room temperature.

The present invention relates to a method of manufacturing a magnetic powder paste for producing a room temperature molded inductor of a coil-embedded type and a magnetic powder paste prepared using the same, and more particularly, to a magnetic powder paste prepared by using a magnetic core and a coil There is provided a method of manufacturing a magnetic powder paste for manufacturing a room temperature molding of a coil-embedded type inductor which improves the characteristics of a buried inductor, and a magnetic powder paste prepared using the method.

Japanese Unexamined Patent Application Publication No. 2003-303711 discloses an iron powder and a method for producing iron powder and iron powder using the same. And a pigment, wherein the lower layer of the film containing the silicone resin and the pigment contains one or more substances selected from the group consisting of a silicon compound, a titanium compound, a zirconium compound, a phosphorus compound and a chromium compound Wherein the pigment is one or more selected from the group consisting of metal oxides, metal nitrides, metal carbides, minerals and glass.

Conventionally, usually, a ferrite powder is processed and stored in the form of a pallet, and when producing a magnetic powder paste, a method of sintering / melting and pulverizing such a pallet and kneading with a polymer has also been used. (Hereinafter referred to as Conventional Art 2).

KR 2007-0030846 A

In the prior art 1, it is impossible to obtain sufficient high temperature stability, and when the heat treatment is performed at a high temperature in the production process of the pressure-sensitive core, the insulation property of the insulating coating is lost due to diffusion of the constituent metal elements of the metal magnetic particles into the coating material The second problem is that if the iron powder with the insulating coating formed thereon is pressure-molded, the insulating coating is damaged by the pressure and the resistance (rho) of the soft magnetic material is lowered so that the eddy current loss can be increased. The fluidity of the insulating film is lowered and the workability and filling property at the time of filling are not good for producing a magnetic core or the like and the density of the molded body is lowered thereby resulting in a third problem.

Also, in the conventional art 2, a separate process is required and productivity is lowered.

In order to solve the above problems, the present invention provides a method of manufacturing a magnetic powder paste for manufacturing a molded inductor, the method comprising the steps of: (i) (S10) for a predetermined time to produce an organic vehicle; (ii) treating the magnetic powder with phosphoric acid to clean and polish the surface of the magnetic powder, and adding the phosphoric acid-treated magnetic powder to the organic vehicle (s20); (iii) a step (s30) of rolling mixing milling the magnetic powder and the organic vehicle, wherein the addition of the magnetic powder in the step (ii) 97 wt% of the organic vehicle and 3 wt% to 50 wt% of the organic vehicle.

The polymer resin may be a liquid at room temperature. The organic vehicle may further include an organic solvent, and the organic vehicle may be composed of 10 to 99.9 wt% of the polymer resin and 0.1 wt% to 90 wt% of the organic solvent. The magnetic powder may include at least one selected from the group consisting of Molybdenum Permalloy Powder (MPP) as a Ni-Fe-based permalloy alloy, a High Flux alloy, and a Mega Flux alloy. The magnetic powder may be characterized in that two or more kinds of magnetic powders having different average particle diameters are mixed. The organic vehicle may also be characterized by further comprising a wetting agent.

The magnetic powder paste is produced by using the method for producing a magnetic powder paste for producing a coil-embedded type inductor of the present invention at room temperature and has a density of 3.0 (g / cc) to 6.0 (g / cc) to provide.

Further, there is provided a coil-embedded type inductor in which a magnetic core is manufactured using the magnetic powder paste of the present invention.

The magnetic powder paste for manufacturing the coil-embedded inductor of the present invention and its manufacturing method are the first effect that the step of insulating the surface of the magnetic particles can be omitted and the process can be simplified, When a device or device such as a buried inductor is manufactured, it has a second effect that a performance element required for the device or the device can be satisfied.

In connection with the second effect, the polymer resin as a binder contained in the magnetic powder paste also functions as an insulator while filling the space between the magnetic powder particles, which is like a fine air gap is dispersed in the magnetic core. As a result, the trajectory of the eddy current is reduced, and the electrical resistance (specific resistance) between the powders is increased to thereby reduce the eddy current loss at the high frequency. As a result, the saturation magnetic flux density, The size of the device can be reduced, and a stable inductance can be ensured in a high frequency and a large current.

Further, an expensive high-pressure press, which is essential in the production process of the conventional pressure-sensitive core, is not required, and the internal stress generated in the magnetic core particles during pressing is not problematic, so that the magnetic loss can be minimized And further an annealing process for removing such internal stress is unnecessary. Further, the melting / pulverizing step of the ferrite pallet or the like can be omitted, which is also advantageous in simplifying the process.

1 is a perspective view showing an embodiment of a coil-embedded type inductor manufactured using the magnetic powder paste of the present invention.
2 is a perspective view showing an embodiment of a coil-embedded type inductor manufactured using the magnetic powder paste of the present invention.

The method of manufacturing a magnetic powder paste for manufacturing a coil-embedded inductor according to the present invention is for producing a magnetic powder paste for manufacturing a magnetic core, and a procedure of kneading a mixture of a polymer resin and a magnetic powder is described in detail Process.

Hereinafter, the configuration of the present invention will be described by the above-described method for each detailed process. First, an organic vehicle is prepared by uniformly stirring the polymer resin under a predetermined temperature condition for a predetermined time. These organic vehicles function to impart fluidity, printability and dryness to the magnetic powder.

The organic vehicle can also be prepared by further including an organic solvent, which affects the viscosity of the organic vehicle and the curing rate of the paste. If a suitable organic solvent is not selected, the drying hardening time becomes longer depending on the thickness of the molded object to be manufactured. Also, if the drying is not performed sufficiently and curing proceeds from the surface, defects such as voids or cracks may occur in the paste cured by the remaining solvents without drying in the cured product. Therefore, in order to reduce or eliminate the use of the organic solvent and ensure the fluidity and printability of the powder, it is possible to consider the use of a polymer resin which is liquid at room temperature.

Further, the organic vehicle can be prepared by further containing an additive, which will be described later.

Polymer resins act as a binder for the added magnetic powder, which not only serves as a structural material in which the shape of the magnetic core is maintained, but also increases the resistivity of the subsequently produced magnetic core, Chemical resistance to organic solvents, and the like. In particular, in the magnetic core molding process to be described later, the magnetic powder and other additives are bonded and supported by the polymer resin in the vehicle, so that a desired shape can be maintained.

In one embodiment relating to the blending ratio of the polymer resin constituting the organic vehicle of the present invention and the organic solvent, it is preferable to mix 10 to 99.9 wt% of the polymer resin and correspondingly the organic solvent at a blending ratio of 0.1 to 90 wt% The mixing ratio in the organic vehicle determines the physical properties such as the viscosity of the magnetic powder paste as well as the compounding ratio between the organic vehicle and the magnetic powder to be described later. If the mixing ratio of the organic vehicle having a relatively low density is increased, the density of the magnetic powder paste is lowered. If the blending ratio of the organic vehicle is decreased, the density of the magnetic powder paste is increased. Therefore, the physical properties of the coil- It will be obvious.

The polymer resin may be selected from the group consisting of acrylic, polyester, thermoplastic polyurethane (TPU), copolymer of ethylene and vinyl acetate (EVA), thermoplastic olefin (TPO), polyamic acid, polyimide, ethyl cellulose (EC), nitrocellulose Urea-based amino, melamine-based amino, bisphenol A-type epoxy, bisphenol F, polyvinylpyrrolidone and the like, and thermoplastic resins such as carboxyethyl cellulose, polyvinyl alcohol, acrylic acid ester, methacrylic acid ester and polyvinyl butyral ethyl cellulose, polysulfone, A thermosetting resin such as phenol novolak type epoxy, flame retardant type epoxy, naphthalene type epoxy, rubber modified epoxy, urethane modified epoxy, polyol epoxy, resol type phenol, , ≪ / RTI > These resins may be used alone or in combination of two or more. Particularly, when a liquid resin is used at room temperature, since it can be used as an organic vehicle without using an organic solvent, there is an advantage that a work process and a drying process can be omitted, and the defect of a manufactured core is reduced. Examples of such a liquid phase resin include a liquid epoxy resin, a liquid silicone resin, and a liquid polyurethane.

Possible materials for organic solvents include Methyl Cellosolve, Ethyl Cellosolve, Butyl Cellosolve, Butyl Cellosolve Acetate, Aliphatic Alcohols, Alcohol, Terpineol, Dihydro-terpineol, Ethylene Grycol, Ethyl carbitol, Butyl carbitol, Butyl carbitol acetate carbitol acetate, Texanol, methyl ethyl ketone, ethyl acetate, cyclohexanone, and the like.

The stirring operation is a process for uniformly mixing the polymer resin with the solvent and the additive, and the process is performed for a predetermined time under a given rpm condition using a mechanical stirrer. There is no upper limit for the agitation time, but a minimum amount of time is required to ensure uniform agitation, which depends on which composition components are agitated and should be determined in each case. Thereafter, the produced organic vehicle can be selectively added with a process of filtering the impurities and removing the internal air bubbles by using a sieve, and the organic vehicle is put into the next process.

Second, a magnetic powder is added to the organic vehicle. In the present invention, it is proposed to mix 50 wt% to 97 wt% of the magnetic powder and 3 wt% to 50 wt% of the organic vehicle with respect to the mixing ratio of the magnetic powder and the organic vehicle. In determining the mixing ratio, as the content of the organic vehicle increases, more polymer is present between each particle of the magnetic powder. This results in the effect of increasing the resistivity of the paste, but the permeability decreases and the saturation flux It should be noted that the disadvantage of decreasing the density is caused.

Such self-component may include at least one selected from Fe-Si-Al-based Sendust alloy, Fe-Si-based alloy, ferrite alloy, amorphous alloy or Ni-Fe-based permalloy alloy. In particular, the Ni-Fe permalloy alloy may include at least one selected from MPP (Molybdenum Permalloy Powder), High Flux alloy, and Mega Flux alloy.

MPP has a high magnetic permeability and has a low core loss, but has a relatively low saturation magnetic flux density and thus has insufficient stability when superimposed with a direct current, has a frequency of 1 MHz or less, contains a large amount of nickel, It is the highest one. High Flux (50% Ni-50% Fe) has high saturation magnetic flux density and high stability when DC is superimposed. Core loss is similar to MPP, but its permeability is relatively low and it contains 50% nickel. Sendust alloy has a relatively high saturation magnetic flux density, low core loss and low cost, but it contains a large amount of silicon (9.5wt%). Because of high elasticity of powder, Sendust alloy has low density even with high pressure molding, DC superposition characteristics with respect to density are low. Mega Flux has a large saturation flux density with a composition of 6.5 wt% Si, low cost, low permeability, and high core loss.

The content of Si in the Fe-Si alloy may be 0.1 to 12 parts by weight based on 100 parts by weight of the Fe-Si alloy. When the content of Si is increased, the resistivity value of the magnetic material is increased to decrease the core loss. However, if the content is too high, the brittleness is increased and the problem of the impact resistance of the magnetic core using the magnetic powder paste It should be noted that this can occur.

Furthermore, the magnetic powder may be composed of a mixture of two or more magnetic powders having different average particle diameters. In this case, the magnetic powder particles having a small particle diameter are located between the magnetic powder particles having a large particle size, which results in an effect of increasing the density of the magnetic powder paste.

Further, the surface of the magnetic powder to be used can be treated with a ceramic coating. The magnetic powder paste of the present invention has a function of insulating the respective magnetic powder particles with the polymer resin included therein to reduce losses due to eddy currents. However, if the surface of the magnetic powder is further coated with a ceramic coating, , Which can be treated with talc, kaolin or the like. As another method for the isolation of magnetic powder particles, acidification can be carried out, for example by phosphoric acid treatment. Such an acid treatment may also have the effect of cleaning and polishing the surface of the magnetic powder particles incidentally.

Third, a mixture of the magnetic powder and the organic vehicle is kneaded (roll mixing milling). The materials to be compounded are weighed and kneaded for a predetermined time so that the organic vehicle and the magnetic powder are evenly mixed. Although there is no upper limit in the time required for the kneading process, a minimum amount of time is required to ensure uniform kneading, which depends on how the organic vehicle and the magnetic powder are used, It should be decided properly.

Further, in the production of the paste, it may be considered to include at least one selected from the group consisting of a diffusing agent, a dispersing agent and a thixotropic agent to improve the flow characteristics, process characteristics and stability of the composition. The dispersant or thixotropic agent is an organic additive which improves the rheological properties and, although they are in small amounts, they greatly change the physical properties and properties of the paste, so that the effect can be obtained even at around 1% of the total weight. Dispersing agents include aliphatic polycarboxylic acid esters, unsaturated fatty acid amine salts; Surfactants such as sorbitan monooleate; And polymer compounds such as polyester amine salts and polyamides. Through their use, pores can be reduced and the effect of evenly dispersing the magnetic powder in the vehicle can be obtained.

With respect to the wetting agent as an additive, in order to increase the permeability and increase the saturation magnetic flux density, the content of the magnetic powder must be increased, which means that the content of the polymer should be relatively reduced. When the content of the magnetic powder is increased and the content of the polymer is decreased, the wettability is insufficient and it becomes difficult to produce the paste. The wetting agent lowers the contact angle between the magnetic powder and the polymer, resulting in a faster penetration of the polymer into the magnetic powder structure, thereby improving the wettability.

With respect to the diluent as an additive, a trifunctional reactive diluent may be applied, and specifically, at least one kind selected from the group consisting of aliphatic glycidyl ether, buthyl glycidyl ether,? Hexanediol diglycidyl ether,? Buthanediol diglycidyl ether, and? Difunctional polyglycidyl epoxide You can choose to use it. The diluent may lower the viscosity of the composition, allow curing at low temperatures, and increase the wettability of the resin-containing composition.

Since the magnetic powder paste prepared by the method of manufacturing the magnetic powder paste of the present invention is used for manufacturing magnetic cores and the like, there is a performance requirement of the magnetic powder paste for satisfying the performance required of the magnetic core, One is the density of the magnetic powder paste. Considering that the density of the magnetic powder is larger than the density of the vehicle, the density of the magnetic powder paste becomes larger as the ratio of the magnetic powder becomes larger. This increases the density of the magnetic powder paste, The magnetic permeability and the saturation magnetic flux density of the magnet are increased. In the magnetic powder paste of the present invention, it is proposed to set the density to 3.0 (g / cc) to 6.0 (g / cc). In this case, a high magnetic permeability can be generally ensured, and the insulation between the magnetic powder particles can be increased. And thermal shock resistance as one of component reliability as a performance requirement of other magnetic powder pastes. In the case of inductors to which a magnetic core is applied, heat of about 130 degrees centigrade usually occurs. However, when an unusually high frequency noise occurs or an abnormal current is generated, an excessive heat of more than 180 degrees centigrade And even if repeatedly exposed to such a temperature, a phenomenon such as occurrence of cracks, discoloration, decrease in adhesion with a coil, etc. should not occur. For this purpose, a combination of polymer resins that satisfy heat resistance is indispensable.

Hereinafter, a coil-embedded type inductor manufactured using the magnetic powder paste of the present invention will be described. The magnetic core, which is a component of the coil-embedded inductor, can be manufactured using the above-described magnetic powder paste. More specifically, the coil 110 is placed in a predetermined position in the mold, Is injected into the mold under a room temperature environment and cured, a magnetic core in which the coil is embedded can be manufactured. Then, when the coil-embedded magnetic core is placed inside the case, the coil-embedded inductor 100 is completed. One embodiment of such a coil-embedded inductor 100 is shown in FIG. 2, a coil (annular type) wound around the bobbins 220a and 220b is prepared, and these bobbins and coils are mounted together at a predetermined position inside the mold When the magnetic powder paste of the present invention is injected into the mold under a room temperature environment and cured, the magnetic core in which the coil and the bobbin are embedded can be manufactured. Then, when the magnetic core is positioned inside the casings 250a and 250b, a coil-embedded inductor 200 with a bobbin is completed.

[Example 1]

Composition ratio

Urethane-modified epoxy vehicle: 2.05 wt%

Polyol Epoxy Vehicle: 0.55 wt%

Fe-Si-Al system Sendust alloy (106 ~ 180μm) 77.9 wt%

Fe-Si-Al system Sendust alloy (30 ~ 50μm) 19.5 wt%

Manufacture of pastes

Two types of epoxy resins were selected and used as an organic vehicle in order to reduce the use of organic solvents and to take account of heat resistance, molding properties and magnetic core properties of the cured product. The magnetic powder was Fe-Si-Al system Sendust alloy powder mixed with 106 ~ 180μm size and 30 ~ 50μm size powder in 4: 1 ratio. Two kinds of organic vehicle, wetting agent and mixed alloy powder were weighed and kneaded for 30 minutes using a rotary stirrer to obtain a paste having a density of 4.15.

3. Manufacture of magnetic core

1.20 g of a modified aromatic amine as a curing agent and 0.17 g of a tertiary amine as a curing accelerator were added to 100 g of the magnetic powder paste and the mixture was mixed and defoamed at room temperature using a planetary mixer (PTE-003) degassing.

Thereafter, the mixture was injected by gravity downward from above the cast in a state of being injected into the tube to completely fill the cast. And cured for 2 hours at a temperature of 120 degrees Celsius for curing. Then, the molded magnetic core was taken out from the cast to prepare a core of TOROIDAL shape having outer diameter / inner diameter of 2.58 cm and 1.36 cm, respectively.

[Example 2]

Except that the wetting agent was not mixed.

[Example 3]

The procedure of Example 1 was repeated except that a reactive diluent was further added to facilitate the workability of the paste.

[Example 4]

The magnetic powder size was measured under the same conditions as in Example 1 except that only Sendust powder having a particle size of 75 nm was used.

[Comparative Example 1]

The magnetic particles were prepared by mixing 4: 1 Fe-Si-Al system Sendust alloy (106 ~ 180 탆) and Fe-Si-Al system Sendust alloy (30 ~ 50 탆), and the silicone resin was SR2410 Respectively. As the pigment, alumina colloidal silica (colloidal concentration: 20% by mass) obtained by mixing alumina sol and silica sol as silica in a ratio of 1: 9 was used, and water was used as a solvent. The total concentration of the pigment and the silicone resin was adjusted to 20 wt%. The agitation and mixing of the pigment, the magnetic powder and the silicone resin were carried out by using a rotary stirrer. After the stirring and mixing, the drying treatment was carried out at room temperature for 10 hours, and then heated and dried at 250 DEG C for 120 minutes. Then, a lubricant was added to and mixed with the magnetic powder having a coating on its surface. As the lubricant, zinc stearate was used, and the amount of the lubricant added was 0.25 parts by weight based on 100 parts by weight of the magnetic particles.

In the production stage of the magnetic core, the composition is poured into a mold, pressed at a pressure of 350 tons by a press machine, and then subjected to an annealing process for 50 minutes at a temperature of 600 degrees Celsius Respectively. Thereafter, the molded magnetic core was taken out of the mold and a core of TOROIDAL shape having outer diameter / inner diameter of 2.58 cm and 1.36 cm was produced.

[Experimental Example 1]

The magnetic permeability of the magnetic cores prepared in Examples 1, 2, 3 and 4 and Comparative Example 1 was measured using an impedance analyzer (HP 4294A), and a large current meter (DPG10). Density was measured using a rotary viscometer (BROOKFIELD viscometer). The core loss was measured using a B-H analyzer (SY-8217). The results are shown in Table 1.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Initial permeability (μ) 22.29 21.41 15.29 16.7 8.19 Effective permeability according to H value
(μ) 0 [Oe] 22.29 21.41 15.29 16.7 8.19 200 [Oe] 15.76 14.94 12.29 12.77 8.19 400 [Oe] 10.8 10.5 8.78 10.06 7.94 Core Loss (mW / cm ³ )
f: 100 kHz, B: 500 G 403 466 476 315 1108 Density (g / cc) 5.41 5.41 4.96 4.76 4.47

When the magnetic powder paste of the present invention was used and the characteristics of the magnetic core manufactured by using the magnetic core production method of the present invention were confirmed through Experimental Example 1, the initial magnetic permeability value was higher than that of Comparative Example, And the core loss is relatively small due to the eddy current. Therefore, it can be confirmed that the core has a magnetic property suitable for the magnetic core.

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, 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.

100: Coil buried inductor
110: Coil (bus bar type)
130: magnetic core
140: Case
200: Bobbin equipped coil embedded type inductor
210: Coil (circular section type)
220a: first bobbin part
220b: second bobbin part
230: magnetic core
250a: first casing part
250b: a second casing part

Claims (15)

1. A method of manufacturing a magnetic powder paste for manufacturing a magnetic core of a coiled inductor by molding at room temperature,
(i) uniformly stirring the polymer resin for a predetermined period of time in consideration of the characteristics of the magnetic core and the workability of the paste to manufacture an organic vehicle (s10);
(ii) treating the magnetic powder with phosphoric acid to clean and polish the surface of the magnetic powder, and adding the phosphoric acid-treated magnetic powder to the organic vehicle (s20);
(iii) a step (s30) of roll mixing milling the magnetic powder and the organic vehicle;
, ≪ / RTI >
The addition of the magnetic powder in the step (ii) is performed at a composition ratio of 50 wt% to 97 wt% of the magnetic powder and 3 wt% to 50 wt% of the organic vehicle,
Wherein the density of the magnetic powder paste obtained after the step (iii) is 3.0 to 6.0 g / cc. The method according to claim 1,
Wherein the polymer resin is a liquid at room temperature. The method according to claim 1,
The organic vehicle in the step (i) further includes an organic solvent,
Wherein the organic vehicle is prepared by mixing 10 to 99.9 wt% of the polymer resin and 0.1 to 90 wt% of the organic solvent. The method according to claim 1,
The polymer resin in step (i) may be selected from the group consisting of acrylic, polyester, thermoplastic polyurethane (TPU), copolymer of ethylene and vinyl acetate (EVA), thermoplastic olefin (TPO), polyamic acid, polyimide, ethylcellulose Ethyl cellulose, EC), nitrocellulose, methylcellulose, carboxycellulose, polyvinyl alcohol, acrylic esters, methacrylic acid esters and polyvinyl butyral ethyl cellulose, polysulfone, phenoxy and
As the thermosetting resin, it is possible to use silicone, urea amino, melamine amino, bisphenol A epoxy, bisphenol F epoxy, phenol novolak epoxy, flame retardant epoxy, naphthalene epoxy, rubber modified epoxy, Polyol-based epoxy, resol-type phenol, and novolak-type phenol. The method according to claim 1,
The magnetic powder in the step (ii) comprises at least one selected from the group consisting of an Fe-Si-Al system Sendust alloy, an Fe-Si alloy, a ferrite, an amorphous alloy or a Ni-Fe permalloy alloy. A method for producing a powder paste. The method of claim 3,
The organic solvent may be selected from the group consisting of methyl cellosolve, ethyl cellosolve, butyl cellosolve, butyl cellosolve acetate, alcohols, terpineol, Dihydro-terpineol, Ethylene Grycol, Ethyl carbitol, Butyl carbitol, Butyl carbitol acetate, Texanol, ), At least one selected from the group consisting of methyl ethyl ketone, ethyl acetate, and cyclohexanone. The method of claim 5,
Wherein the Ni-Fe permalloy alloy comprises at least one selected from MPP (Molybdenum Permalloy Powder), High Flux alloy, and Mega Flux alloy. The method of claim 5,
Wherein the content of Si in the Fe-Si-based alloy is 0.1 to 12 parts by weight based on 100 parts by weight of the Fe-Si alloy. The method according to claim 1,
Wherein the magnetic powder in the step (ii) is a mixture of two or more kinds of magnetic powders having different average particle diameters. The method according to claim 1,
Wherein the magnetic powder in the step (ii) has a surface coated with a ceramic coating. The method according to claim 1,
Wherein the organic vehicle further comprises a wetting agent. The method according to claim 1,
The organic vehicle may comprise at least one additive selected from the group consisting of a diffusing agent, a dispersing agent, a diluent,
Further comprising the step of forming a magnetic powder paste. delete 1. A coil-embedded inductor comprising a magnetic core,
Wherein the magnetic core is manufactured by using a magnetic powder paste produced by the method of claim 1. delete

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