TWI597743B - Producing method of soft magnetic composite, soft magnetic composite, producing method of magnetic core and magnetic core - Google Patents

Description

Soft magnetic composite material manufacturing method, soft magnetic composite material Material, magnetic core manufacturing method and magnetic core

The present invention relates to a manufacturing method, and in particular to a method of manufacturing a soft magnetic composite material having high surface resistance.

With the development trend of miniaturization of electrical equipment, the development of micro-magnetic cores has become more and more important. In order to produce magnetic cores with higher efficiency, smaller size and lighter weight, soft magnetic composites (SMCs) are used to make one of the main research directions of magnetic core systems. Among them, the soft magnetic composite material is a composite material composed of a soft magnetic alloy powder and an insulating medium.

Soft magnetic composite materials have high magnetic permeability and low iron loss in high frequency environment (1 kHz to 1 MHz), and can be applied to conventional electromagnetic steel sheets (ES) and soft magnetic ferrites (Soft Magnetic Ferrite). The frequency band of the application. Secondly, soft magnetic composites are in the middle and high frequency sections (10 kHz to 100 kHz) compared to conventional electromagnetic steel sheets and soft ferrites. It also has a high magnetic flux density and good insulation properties. Therefore, the soft magnetic composite material can be applied to high frequency and/or high current AC devices.

In order to improve the magnetic permeability of soft magnetic composite materials, the conventional method is aimed at reducing the iron loss, wherein the source of iron loss is mainly the hysteresis loss and the Eddy Current Loss of the material itself. Among them, according to the formula of eddy current loss ( P _e ) and operating frequency ( f ) [shown in the following formula (I)], the eddy current loss is proportional to the square of the operating frequency, so in the high frequency operating environment, the vortex Current loss is the main cause of core power loss. Second, the eddy current losses are derived from inter-particles ( P _e ^inter ) and intra-particles (Intra-particles, P _e ^intra ) induced eddy currents:

Furthermore, the formula of the eddy current loss of the magnetic core [shown in the following formula (II)] shows that the overall resistance value ( ρ _B ) of the magnetic core and the electrical resistivity ( ρ _R ) of the alloy powder itself are respectively between the above particles. And the index factor of the degree of loss of induced eddy current in the particle:

According to the above formula (II), when the soft magnetic composite material has the same magnetic powder composition and particle diameter, the magnetic permeability, hysteresis loss and induced eddy current in the soft magnetic composite material do not greatly differ. Therefore, in order to further reduce the iron loss, the induced eddy current loss between the particles must be effectively reduced.

Accordingly, the surface of the alloy magnetic powder must be insulated to block the transfer of eddy current between the particles, thereby increasing the overall resistance value ( ρ _B ), thereby reducing the iron loss.

The conventional insulation treatment is performed by coating an insulating layer having a high insulation resistance on the surface of the soft magnetic composite material. The insulating coating technique used may be an organic insulating coating and an inorganic insulating coating. Among them, since the manufacturing process of the magnetic core generally includes heat treatment of not less than 500 ° C, in order to avoid high temperature damage to the insulating layer, it is conventionally known that an organic polymer material such as an epoxy resin or a rubber is less suitable for a high temperature process.

One of the aforementioned inorganic insulating coatings is carried out by phosphating or sodium citrate coating. The phosphating treatment uses a phosphoric acid or phosphate solution to carry out a conversion reaction with an iron atom on the surface of the alloy to form a phosphate film. However, the phosphate film is rapidly deteriorated in a high temperature state (greater than 500 ° C), and the insulating layer between the particles is disabled, thereby increasing the eddy current loss of the magnetic core.

Another method is to form a magnesium oxide insulating layer on the surface of the alloy powder by vapor-depositing magnesium metal. Although the magnesium oxide insulating layer has high temperature resistance, the operation of the vacuum evaporation system is complicated, and the cost thereof is low, so the commercial value is low.

In another method, the water glass insulating layer formed by the bismuth acid salt is directly coated on the surface of the alloy powder, and after drying and removing water, a glass phase network structure can be formed on the surface of the alloy powder. . The glass phase network structure can control the insulating properties by adjusting its thickness, and it has better thermal stability. However, the surface roughness of the alloy powder is high, and its appearance is an irregular structure. Therefore, when the water glass insulating layer is coated on the surface of the alloy powder, the water glass insulating layer is not easily coated uniformly, and the density thereof is lowered. It is easy to form an insulating layer having defects (that is, the aforementioned defective glass phase network structure).

In view of the above, it is extremely desirable to provide a method of manufacturing a soft magnetic composite material and an application thereof to improve the manufacturing method of the conventional soft magnetic composite material and the defects thereof.

Accordingly, an aspect of the present invention provides a method of manufacturing a soft magnetic composite material. This manufacturing method can produce a soft magnetic composite material having an insulating film, and the insulating film has high density, high insulation resistance, and good thermal stability.

Another aspect of the present invention is to provide a soft magnetic composite material. This soft magnetic composite material is obtained by the aforementioned method.

Yet another aspect of the present invention is to provide a method of fabricating a magnetic core. This manufacturing method uses the soft magnetic composite material described above to make a magnetic core.

Yet another aspect of the present invention is to provide a magnetic core. This core has good magnetic permeability and low iron loss.

According to an aspect of the present invention, a method for producing a soft magnetic composite material is provided. The manufacturing method first provides a precursor mixture and performs a lyotropic reaction on the precursor mixture to obtain a phosphor glass sol.

The foregoing precursor mixture comprises a reactant and an organic solvent, and the reactant comprises a phosphoric acid compound and a decane monomer.

Wherein, the total amount of the reactants used is 100% by mole, and the amount of the phosphate compound used is 20% by mole to 66% by mole The ratio of decane monomer used is from 34 mole percent to 80 mole percent. The total amount of the precursor mixture used is 100% by weight, the aforementioned reactant is used in an amount of 10% by weight to 50% by weight, and the organic solvent is used in an amount of 50% by weight to 90% by weight.

The aforementioned sol-gel reaction is carried out at 60 ° C to 80 ° C for 30 minutes to 60 minutes to prepare a phosphor glass sol.

Next, the phosphor glass sol and the iron-based soft magnetic powder are mixed and dried at 100 ° C to 300 ° C for 1 hour to 2 hours to obtain a soft magnetic composite material. The mixing time of the phosphorus glass sol and the iron-based soft magnetic powder is 10 minutes to 60 minutes.

According to an embodiment of the invention, the phosphoric acid compound comprises inorganic phosphoric acid, organic phosphoric acid or an organic phosphate ester.

According to another embodiment of the present invention, the iron-based soft magnetic powder has a particle diameter of from 25 μm to 250 μm.

According to still another embodiment of the present invention, the aforementioned lyophilization reaction is carried out for 60 minutes.

According to another aspect of the invention, a soft magnetic composite material is proposed. This soft magnetic composite material contains a phosphorus glass phase. The phosphorus glass phase is contained in an amount of from 0.1% by weight to 2% by weight based on 100% by weight of the soft magnetic composite material.

According to still another aspect of the present invention, a method of fabricating a magnetic core is proposed. This method performs a molding step on the soft magnetic composite material at a molding pressure of at least 800 MPa to form an embryo body. Next, heat the embryo body Steps to form a magnetic core. Wherein, the heat treatment step is carried out at 700 ° C to 800 ° C for 30 minutes to 60 minutes.

According to an embodiment of the invention, the method further comprises adding a lubricant to the soft magnetic composite prior to performing the forming step. Wherein, the amount of the iron-based soft magnetic powder used is 100% by weight, and the amount of the lubricant used is 0.5% by weight to 5% by weight.

According to another embodiment of the present invention, the aforementioned molding pressure is from 800 MPa to 1400 MPa.

According to still another embodiment of the present invention, the aforementioned embryo system is subjected to a heat treatment step in an inert gas.

According to still another aspect of the present invention, a magnetic core is proposed. The magnetic core is fabricated by the method described above, and the magnetic core has an insulation resistance value of not less than 10 ⁹ Ω.

The method for producing a soft magnetic composite material according to the present invention is a lyogel reaction of a phosphoric acid compound and a decane monomer to obtain a phosphorus glass sol, and can be mixed with an iron-based soft magnetic powder to obtain a soft magnetic composite. The material, and the surface of the soft magnetic composite material has a uniform and dense oxide insulating film. Secondly, the magnetic core having good magnetic properties can be obtained by further performing a forming step and a heat treatment step on the prepared soft magnetic composite material.

100‧‧‧ method

110‧‧‧Procedures for providing precursor mixtures

120‧‧‧Steps of mixing phosphorus glass sol and iron-based soft magnetic powder

130‧‧‧Steps for sol-gel reaction of precursor mixtures

140‧‧‧Steps of drying and mixing the phosphorous glass sol and the iron-based soft magnetic powder

150‧‧‧Steps for making soft magnetic composites

200‧‧‧ method

210‧‧‧Steps for the molding step of soft magnetic composites

220‧‧‧Steps for heat treatment of the embryo body

230‧‧‧Steps to form a magnetic core

501/503/505/507‧‧‧ trend line

For a more complete understanding of the embodiments of the invention and the advantages thereof, reference should be made to the description below and the accompanying drawings. Must be emphasized Yes, the various features are not drawn to scale and are for illustrative purposes only. The related drawings are described as follows: [Fig. 1] is a flow chart showing a method of manufacturing a soft magnetic composite material according to an embodiment of the present invention.

FIG. 2 is a flow chart showing a method of manufacturing a magnetic core according to an embodiment of the present invention.

[Fig. 3a] to [Fig. 3d] are scanning electron microscopy (SEM) images of soft magnetic composite materials according to Examples 1-1 to 1-3 and Comparative Example 1-1 of the present invention, respectively. And Energy Dispersive X-ray Spectroscopy (EDS).

[Fig. 4a] to Fig. 4f show the soft magnetic composite prepared by the iron-based soft magnetic powder according to the present invention and the examples 2-1 to 2-3 and the comparative examples 2-1 to 2-2. SEM image of the material.

Fig. 5 is a graph showing the surface impedance versus molding pressure of Examples 3-1 to 3-3 and Comparative Example 3-1 according to the present invention.

Fig. 6 is a graph showing changes in the saturation magnetic flux density versus the equivalent ratio of phosphoric acid to decane according to Example 4-1 to Example 4-5 of the present invention and Comparative Example 4-1.

Fig. 7a and Fig. 7b are graphs showing changes in magnetic permeability or iron loss in Example 5-1 and Comparative Example 5-1 to Comparative Example 5-3, respectively, according to the present invention.

Fig. 8a and Fig. 8b are respectively an SEM image and an Electron Probe X-ray MicroAnalyzer (EPMA) diagram showing the cross-section of the magnetic core according to Example 6 and Comparative Example 6 of the present invention.

The making and using of the embodiments of the invention are discussed in detail below. However, it will be appreciated that the embodiments provide many applicable inventive concepts that can be implemented in a wide variety of specific content. The specific embodiments discussed are illustrative only and are not intended to limit the scope of the invention.

Please refer to FIG. 1 , which is a flow chart showing a method of manufacturing a soft magnetic composite material according to an embodiment of the present invention. In one embodiment, the method 100 first provides a precursor mixture, as shown in step 110.

The precursor mixture comprises a reactant and an organic solvent, and the reactant comprises a phosphoric acid compound and a decane monomer.

The phosphoric acid compound of the present invention comprises inorganic phosphoric acid, organic phosphoric acid, an organic phosphate ester, other suitable phosphoric acid compounds, or any mixture of the above materials.

The aforementioned inorganic phosphoric acid may be represented by H _x PO _y , wherein x represents an integer of 1 to 3, and y represents an integer of 2 to 4. In a specific example, the inorganic phosphoric acid of the present invention may be any mixture of phosphoric acid, phosphorous acid, hypophosphorous acid, metaphosphoric acid, polyphosphoric acid, other suitable inorganic phosphoric acid or the above inorganic phosphoric acid.

The aforementioned organic phosphoric acid may be represented by R-PO(OH) ₂ wherein R represents an organic functional group, and the organic functional group may be an alkyl group, an alkoxy group or an aromatic group. In a specific example, the organic phosphoric acid of the present invention may be any combination of ethyl phosphoric acid, propyl phosphoric acid, other suitable organic phosphoric acid or the above organic phosphoric acid.

The aforementioned organic phosphates may be represented by PO(OR) ₃ , wherein OR represents an alkoxy group having a carbon number of 1 to 6, respectively. In a specific example, the organic phosphate of the present invention may be trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, triamyl phosphate, other suitable organic phosphates or any of the above materials. mixing.

The total amount of reactants used is 100 mole percent and the phosphate compound is used in an amount from 20 mole percent to 66 mole percent.

The aforementioned decane single system refers to a monomer compound which can be polymerized to form a polysiloxane molecule, and its structure can be represented by Si-(OR) ₄ or -Si-(OR) ₃ , wherein OR represents another organic functional group, And OR may represent methoxy, ethoxy or 3-aminopropyltriethoxy. In one embodiment, the decane monomer of the present invention may be 3-aminopropyltriethoxydecane, tetraethoxydecane, trimethoxydecane, tetramethoxydecane, triethoxydecane, and other suitable Any mixture of decane monomers or the above materials.

The total amount of reactants used is 100 mole percent and the amount of decane monomer used is from 34 mole percent to 80 mole percent.

If the amount of the phosphoric acid compound used is less than 20 mole percent, the amount of the decane monomer used will be greater than 80 mole percent, and the phosphorus glass phase in the soft magnetic composite material produced by the present invention described below is reduced.

If the amount of the phosphoric acid compound used is more than 66% by mole, the pH of the reaction environment is lowered due to the excessive use of the phosphoric acid compound, and the reaction time for accelerating the following sol-gel reaction is accelerated, thereby causing the precursor mixture to instantaneously condense. Gelling, thus affecting the mixing of the splicing with the iron-based soft magnetic powder and reducing its drape effect.

The reactants may be used in an amount of from 10% by weight to 50% by weight based on the total amount of the precursor mixture used in an amount of 100% by weight.

The organic solvent may be a mixed solvent of an alcohol organic solvent and water, and the alcohol organic solvent may be methanol, ethanol, isopropanol, butanol, other suitable alcoholic organic solvents or organic alcohol solvents. Mix arbitrarily.

The organic solvent may be used in an amount of 50% by weight to 90% by weight based on 100% by weight of the total amount of the precursor mixture.

Next, the precursor mixture is subjected to a lyogel reaction as shown in step 120. This lyogel reaction can be carried out at 60 ° C to 80 ° C for 30 minutes to 60 minutes to prepare a phosphor glass sol.

Since the reactant of the precursor mixture contains a phosphoric acid compound, the lyotropic reaction is carried out in an acidic environment. In one embodiment, when the lyotropic reaction is carried out in an alkaline environment (ie, the aforementioned reactant does not contain a phosphate compound), the decane monomer in the precursor mixture can still undergo a sol-gel reaction and form a decane glass. The sol, however, lacks a reactant for supplying phosphorus atoms in the reactants, so the decane glass sol is not the phosphor glass sol prepared in the foregoing.

If the reaction temperature of the lyogel reaction is lower than 60 ° C, the degree of polymerization of the obtained phosphorus glass sol is low, so that the phosphorus glass sol cannot form a network structure, so when the subsequent phosphorus glass sol is mixed with the iron-based soft magnetic powder The phosphor glass sol is difficult to completely cover the surface of the iron-based soft magnetic powder, and the insulating property of the soft magnetic composite material produced by the present invention is lowered.

If the reaction temperature of the lyogel reaction is greater than 80 ° C, the speed of the lyotropic reaction is too fast, so that the precursor mixture is gelled instantaneously, thereby reducing the subsequent coating effect on the iron-based soft magnetic powder, thereby reducing the present The insulating properties of the soft magnetic composite material produced by the invention.

In one embodiment, the aforementioned lyogel reaction can be carried out at 60 ° C to 80 ° C for 60 minutes.

After performing step 120, the phosphorous glass sol and the iron-based soft magnetic powder are mixed as shown in step 130. The mixing time of the phosphorus glass sol and the iron-based soft magnetic powder may be 10 minutes to 60 minutes. When the mixing time is from 10 minutes to 60 minutes, the magnetic core has better magnetic properties, and the insulating coating layer has a suitable thickness, and can take into consideration the magnetic properties of the magnetic core and the insulating coating. thickness.

If the mixing time is less than 10 minutes, the mixing uniformity of the phosphorus glass sol and the iron-based soft magnetic powder is poor, and the denseness of the insulating coating layer in the magnetic core is lowered, thereby reducing the magnetic properties of the prepared magnetic core. If the mixing time is longer than 60 minutes, the thickness of the insulating coating layer in the obtained magnetic core is too thick, and the magnetic permeability of the magnetic core is lowered.

The foregoing iron-based soft magnetic powder may be iron powder, iron-bismuth powder, iron-bismuth-aluminum powder, iron-bismuth-chromium powder, other suitable iron-based soft magnetic powder or any mixture of the above powders. . In one embodiment, the iron-based soft magnetic powder may be produced by a water jet method, a gas jet method, a casting pulverization method, other suitable methods, or any combination of the above methods.

When the phosphorus-phosphorus sol and the iron-based soft magnetic powder are mixed, the phosphor glass sol may be formulated as a liquid or a colloid, or in an atomized form, in contact with the iron-based soft magnetic powder, and coated on the surface of the iron-based soft magnetic powder. In one embodiment, this step may be performed by mixing a phosphor glass sol with an iron-based soft magnetic powder by a fluidized bed, a vertical agitation, a horizontal uniaxial double helix mixing or an atomizing drying device.

When the phosphor glass sol is mixed with the iron-based soft magnetic powder, the phosphoric acid in the phosphor glass sol undergoes a conversion reaction with the elemental iron on the surface of the iron-based soft magnetic powder, and the elemental iron is converted into ferrous phosphate. Further, a passivation film is formed on the surface of the iron-based soft magnetic powder.

Next, the phosphor glass sol can form a uniform Phosphorus Silicate Glass (PSG) layer on the surface of the iron-based soft magnetic powder and form an insulating coating layer.

The iron-based soft magnetic powder has a particle diameter of 25 μm to 250 μm.

When the decane monomer is subjected to a lyotropic reaction in an environment free of acidic catalysis, the lyotropic reaction rate is slow, and the appearance of the decane glass sol formed by the polymerization is mostly a granular appearance structure, and the non-network The appearance of the structure is therefore less likely to be coated on the iron-based soft magnetic powder.

Next, the mixed phosphor glass sol and the iron-based soft magnetic powder are dried to obtain a soft magnetic composite material as shown in steps 140 and 150.

The mixed phosphorus glass sol and iron-based soft magnetic powder system are dried at 100 ° C to 300 ° C for 1 hour to 2 hours.

In one embodiment, the soft magnetic composite material produced comprises a phosphorous glass phase. In the foregoing step 130, the phosphorus glass phase is formed on the surface of the iron-based soft magnetic powder to achieve the effect of insulation. Secondly, since the phosphorus glass phase has good thermal stability, the soft magnetic composite material obtained has good thermal stability and can withstand the high temperature of the heat treatment step of the subsequent magnetic core.

The phosphorus glass phase is contained in an amount of from 0.1% by weight to 2% by weight based on 100% by weight of the soft magnetic composite material.

If the content of the phosphorus glass phase is less than 0.1% by weight, the thermal stability of the soft magnetic composite material produced is poor and the insulation resistance value is low, and the denseness of the coating layer formed by the phosphorus glass phase is poor.

If the content of the phosphorus glass phase is more than 2% by weight, the insulating coating on the surface of the soft magnetic composite material is too thick, and the surface resistance of the soft magnetic composite material is increased, and the magnetic permeability is lowered.

Please refer to FIG. 2, which is a flow chart showing a method of manufacturing a magnetic core according to an embodiment of the present invention. In one embodiment, the method 200 first proceeds to the aforementioned soft magnetic composite forming step, as shown in step 210. The molding step molds the soft magnetic composite material at a molding pressure of at least 800 MPa to form an embryo body.

If the aforementioned molding pressure is less than 800 MPa, the molding pressure which is too small cannot compact the soft magnetic composite material, and the embryo body cannot be formed. In an embodiment, the molding pressure may be from 800 MPa to 1400 MPa.

In one embodiment, the method 200 can selectively add a lubricant to the soft magnetic composite prior to performing the foregoing step 210. After the mixture is uniformly mixed, it is subjected to a molding step.

Before entering the forming step, the lubricant can lubricate the contact surface of the soft magnetic composite material with the mold to avoid damage to the mold surface of the soft magnetic composite material during high pressure molding. Alternatively, when the molding step is performed, the lubricant can make the formed body body easier to release from the mold, thereby reducing the damage of the mold.

In a specific example, the lubricant may be a stearic acid or a stearate, and the stearate may include, but is not limited to, calcium stearate, a hard ester. Aluminum acid, zinc stearate, magnesium stearate, other suitable stearates or any combination of the above.

The lubricant is used in an amount of from 0.5% by weight to 5% by weight, based on the amount of the iron-based soft magnetic powder used in the soft magnetic composite material, and preferably from 0.5% by weight to 2% by weight.

If the amount of the lubricant used is less than 0.5% by weight, too little lubricant cannot effectively lubricate the contact surface of the soft magnetic composite material with the mold, and it is difficult to reduce the damage of the soft magnetic composite material to the mold. If the amount of the lubricant used is more than 5% by weight, too much lubricant is dispersed between the soft magnetic composite materials to lower the compactness of the formed embryo body. What is more, the soft magnetic composite material cannot be molded into an embryo body.

The body is then subjected to a heat treatment step to form a magnetic core, as shown in steps 220 and 230.

The heat treatment step is carried out at 700 ° C to 800 ° C for 30 minutes to 60 minutes. In one embodiment, the heat treatment step is carried out in an inert gas and the inert gas may be nitrogen.

If the temperature of the heat treatment step is less than 700 ° C, too little heat can not form a magnetic core with stable structure, and has high magnetic permeability and low iron loss. If the temperature of the heat treatment step is greater than 800 ° C, the excessive heat treatment temperature may easily damage the passivation film and/or the insulating coating between the soft magnetic composite materials in the magnetic core, thereby reducing the surface impedance of the magnetic core, thereby increasing the eddy current of the magnetic core. Eddy Current Loss, thus reducing the magnetic permeability of the core.

In one embodiment, the resulting core insulation resistance value of not less than 10 ⁹ Ω.

The following examples are used to illustrate the application of the present invention, and are not intended to limit the present invention, and various modifications and refinements can be made without departing from the spirit and scope of the invention.

Method for manufacturing soft magnetic composite material Example 1-1

First, 40 weight percent aqueous phosphoric acid (H ₃ PO ₄ ) and tetraethoxysilane were prepared as reactants having an equivalent ratio of 1:1. Then, the sol-gel reaction was carried out at 60 ° C, and after 1 hour, a phosphorus glass sol was obtained.

Next, based on the iron-based soft magnetic powder used in an amount of 100% by weight, 10 parts by weight of the phosphorus glass sol and the iron-based soft magnetic powder are mixed by vertical mechanical stirring or horizontal uniaxial double-helical mechanical stirring, and further added 2 The weight percent of calcium stearate is stirred and mixed.

After mixing for 30 minutes, it was dried at 200 ° C for 1 hour, and sieved at 80 mesh to obtain a soft magnetic composite material of Example 1-1.

Example 1-2 to Example 1-3

Examples 1-2 to 1-3 were the same as the manufacturing method of the soft magnetic composite material of Example 1-1, except that Examples 1-2 to 1-3 changed the reactants. Matching. The ratio of the equivalents of the aqueous phosphoric acid solution to the tetraethoxy decane of Example 1-2 was 1:2, and the ratio of the equivalents of the aqueous phosphoric acid solution of Example 1-3 to tetraethoxy decane was 1:4.

Comparative Example 1-1

First, 40% by weight of sodium citrate stock solution (Na ₂ O‧nSiO ₂ ‧xH ₂ O; n=2.8 to 3.3; Na ₂ O: 8 to 10%; and SiO ₂ : 23 to 30%) Ionized water was diluted to prepare a sodium citrate salt sol having a volume ratio of 1:1.

Next, based on the iron-based soft magnetic powder used in an amount of 100% by weight, the 3 parts by weight of the phosphorus glass sol and the iron-based soft magnetic powder are mixed by vertical mechanical stirring or horizontal uniaxial double-helical mechanical stirring, and further added 2 The weight percent of calcium stearate is stirred and mixed.

After mixing for 60 minutes, it was dried at 200 ° C for 1 hour, and sieved at 80 mesh to obtain a soft magnetic composite material of Comparative Example 1-1.

Referring to FIG. 3a to FIG. 3C, respectively, a scanning electron microscope (SEM) image and an energy dispersive X-ray of a soft magnetic composite material according to Embodiment 1-1 to Embodiment 1-3 of the present invention are shown. Energy Dispersive X-ray Spectroscopy (EDS) map. Among them, (1) of each figure shows the SEM image of the soft composite material; (2) of each figure shows the oxygen of the SEM image of Fig. 3a (1), Fig. 3b (1) and Fig. 3c (1), respectively. The EDS map of the atom; and (3) of each graph shows the EDS map of the phosphorus atom of the SEM image of Fig. 3a (1), Fig. 3b (1) and Fig. 3c (1), respectively. The magnification of the SEM image of (1) of each figure is 10000 times, and the length of the scale rule of (2) and (3) of each figure represents 25 micrometers.

According to the contents shown in FIG. 3a to FIG. 3c, the surface of the soft magnetic composite material produced has an oxide film (that is, the above-mentioned passivation film and/or insulating coating layer), and the oxide film increases with the increase of phosphoric acid equivalent. More uniform The ground is coated on the surface of the iron-based soft magnetic powder. Secondly, according to the content shown in the EDS diagram, as the number of equivalents of phosphoric acid increases, the distribution of phosphorus atoms and oxygen atoms becomes denser.

Further, please refer to Fig. 3d which shows an SEM image and an EDS diagram of the soft magnetic composite material of Comparative Example 1-1 according to the present invention. (1) shows an SEM image of the soft magnetic composite material of Comparative Example 1-1, and the magnification thereof is 10000 times; and (2) shows an EDS diagram of an oxygen atom of the SEM image of FIG. 3d (1), and The length of the scale ruler represents 25 μm. According to the SEM image of Fig. 3d (1), the obtained soft magnetic composite material has an oxide film, but is coated with the oxide film of Comparative Example 1-1 as compared with Examples 1-1 to 1-3. The effect is poor. Further, according to the EDS diagram of Fig. 3d (2), the distribution of oxygen atoms is relatively loose.

Accordingly, the surface of the soft magnetic composite material prepared by the invention has a uniform oxide film, and the distribution of oxygen atoms and phosphorus atoms is relatively dense, so the soft magnetic composite material prepared by the invention can have better surface resistance, and can be Avoid eddy current effects.

Example 2-1

First, a 40% by weight aqueous solution of phosphoric acid and tetraethoxydecane were prepared as a reactant having an equivalent ratio of 1:1. Then, the sol-gel reaction was carried out at 60 ° C, and after 60 minutes, a phosphorus glass sol was obtained.

Next, based on the use amount of the iron-based soft magnetic powder, 100% by weight, by vertical mechanical stirring or horizontal single-axis double-helical mechanical stirring 10 parts by weight of the phosphorus glass sol and the iron-based soft magnetic powder were further mixed with 2% by weight of calcium stearate.

After mixing for 10 minutes, it was dried at 200 ° C for 1 hour, and sieved at 80 mesh to obtain a soft magnetic composite material of Example 2-1.

Example 2-2 to Example 2-3

Example 2-2 to Example 2-3 were the same as the manufacturing method of the soft magnetic composite material of Example 2-1, except that Example 2-2 to Example 2-3 were changed to dissolve the sol gel. Reaction reaction time. The reaction time of the lyotropic reaction of Example 2-2 was 30 minutes, and the reaction time of the lyotropic reaction of Example 2-3 was 60 minutes.

Comparative Example 2-1

In Comparative Example 2-1, the same production method as that of the soft magnetic composite material of Comparative Example 1-1 was used, and the same composition and composition were selected.

Comparative Example 2-2

In Comparative Example 2-2, a production method similar to the production method of the conventional phosphating treatment was used to form a phosphate film on the surface of the iron-based soft magnetic powder. The concentration of the aqueous phosphoric acid solution was 10% by weight, and the phosphating treatment time was 1 hour. After the phosphating treatment, the soft magnetic composite material of Comparative Example 2-2 was obtained.

Please refer to FIG. 4a to FIG. 4f, which show the soft magnetic powder prepared by the iron-based soft magnetic powder according to the present invention and the examples 2-1 to 2-3 and the comparative examples 2-1 to 2-2. SEM image of the composite material, and its magnification 10,000 times. 4a shows an SEM image of the surface of the iron-based soft magnetic powder; and FIGS. 4b to 4f show the soft magnetic composite of the embodiment 2-1 to the embodiment 2-3 and the comparative example 2-1 to the comparative example 2-2, respectively. SEM image of the material.

According to FIG. 4a, the surface of the iron-based soft magnetic powder is uneven, so when the above-mentioned oxide film is to be coated on the surface of the iron-based soft magnetic powder, if the coating effect of the oxide film is not good, it is obtained. The soft magnetic composite material is prone to surface defects, which causes surface impedance to decrease, and is susceptible to eddy current effects, thereby reducing magnetic permeability.

According to FIG. 4b to FIG. 4d, as the reaction time of the lyotropic reaction increases, the coating effect of the oxide film on the iron-based soft magnetic powder increases, and the oxide film becomes denser. Secondly, as the reaction time increases, the uniformity of the oxide film increases, and the surface smoothness of the soft magnetic composite material obtained is improved.

However, according to Fig. 4e and Fig. 4f, the water glass insulating coating layer (Comparative Example 2-1) and the phosphate film (Comparative Example 2-2) formed by sodium citrate were relatively inferior in surface coating effect. Secondly, when the time of the phosphating treatment (Comparative Example 2-2) was the same as the reaction time of the lyotropic reaction (Example 2-3), the coating effect of the phosphate film was also relatively poor.

Please refer to the following table, which lists the EDS composition analysis results of the soft magnetic composite materials prepared in Examples 2-1 to 2-3:

According to the above table, as the reaction time increases, the proportion of phosphorus and oxygen increases. Therefore, in addition to adjusting the composition ratio of the reactants of the precursor mixture and changing the composition characteristics of the oxide layer, the present invention can also adjust the oxide film of the soft magnetic composite material prepared by adjusting the reaction time of the lyotropic reaction. The effect of the overlay.

Making a magnetic core Example 3-1

First, 40 weight percent aqueous phosphoric acid (H ₃ PO ₄ ) and tetraethoxysilane were prepared as reactants having an equivalent ratio of 1:1. Then, the sol-gel reaction was carried out at 60 ° C, and after 1 hour, a phosphorus glass sol was obtained.

Next, based on the iron-based soft magnetic powder used in an amount of 100% by weight, 10 parts by weight of the phosphorus glass sol and the iron-based soft magnetic powder are mixed by vertical mechanical stirring or horizontal uniaxial double-helical mechanical stirring, and further added 2 The weight percent of calcium stearate is stirred and mixed. After mixing for 1 hour, it was dried at 200 ° C and sieved at 80 mesh to obtain a soft magnetic composite material of Example 3-1.

Then, 1 g of the aforementioned soft magnetic composite material was taken and molded under different pressure to form square test pieces having a length and width of 7.1 mm and 9.6 mm, respectively. The square test pieces obtained by different pressures were measured by four-point probe and high-resistance measurement, and the measured surface impedance is shown in Fig. 5.

Example 3-2 to Example 3-3

Examples 3-2 to 3-3 were the same as the manufacturing method of the magnetic core of Example 3-1, except that Examples 3-2 to 3-3 changed the phosphor glass sol and Mixing time of iron-based soft magnetic powder. The mixing time of Example 3-2 was 30 minutes, and the mixing time of Example 3-3 was 10 minutes. The surface impedance of the square test piece prepared by the different pressures of Examples 3-2 to 3-3 is shown in Fig. 5.

Comparative Example 3-1

In Comparative Example 3-1, 1 g of the soft magnetic composite material obtained in the above Comparative Example 1-1 was weighed. Then, the soft magnetic composite material was molded at a different pressure to obtain a square test piece. Similarly, the surface impedance was measured by a four-point probe and a high resistance meter, and the measured surface impedance is shown in FIG.

Please refer to FIG. 5 , which is a graph showing surface impedance versus molding pressure according to Examples 3-1 to 3-3 and Comparative Example 3-1 of the present invention, wherein the X axis represents the application time during the molding step. Molding pressure, in MPa, and the Y-axis represents surface impedance in Ω.

In FIG. 5, the trend line 501 represents a curve of a square test piece prepared in accordance with Embodiment 3-1; the trend line 503 represents a curve of a square test piece prepared in accordance with Embodiment 3-2; and the trend line 505 represents The curve of the square test piece obtained in Example 3-3; and the trend line 507 represents the curve of the square test piece prepared in accordance with Comparative Example 3-1.

In FIG. 5, the square test piece obtained can have a better insulation table as the mixing time of the mixed phosphorus glass sol and the iron-based soft magnetic powder is increased. Now. Secondly, under the different molding pressures, the soft magnetic composite materials having the water glass coating layer prepared in Comparative Example 3-1 were coated with the inventive examples 3-1 to 3-3. The soft magnetic composite materials of the oxide film have high surface resistance values.

In the trend line 501, the surface impedance of the soft magnetic composite material of Example 3-1 was not greatly attenuated when the molding pressure was increased. Among them, when the molding pressure is 1400 MPa, the surface resistance can still be 4 × 10 ¹¹ Ω.

Trends in line 503, the same as in Example 3-1 of the soft magnetic composites embodiment, a surface of the impedance-based soft magnetic composite material in Example 3-2 is greater than 10 ⁹ Ω, and which is not susceptible to increased molding pressure is attenuated.

In the trend line 505, the surface resistance of the soft magnetic composite material of Example 3-3 was about 10 ⁹ Ω. Wherein, when the molding pressure is greater than or equal to 1200 MPa, the surface impedance of the soft magnetic composite material of Example 3-3 is attenuated, but the surface impedance is still greater than that of the soft magnetic composite having the water glass coating layer prepared in Comparative Example 3-1. The surface impedance of the material.

In the trend line 507, when the molding pressure does not exceed 1000 MPa, the obtained soft magnetic composite material may have a surface resistance of 10 ⁸ Ω to 10 ⁹ Ω, but when the molding pressure is more than 1000 MPa, the surface resistance value thereof is greatly attenuated. Among them, when the molding pressure was 1200 MPa, the surface resistance of the soft magnetic composite material of Comparative Example 3-1 was only 10 ⁶ Ω to 10 ⁵ Ω.

In Fig. 5, the larger molding pressure causes the oxide layer on the surface of the soft magnetic composite material to be crushed and fractured, and the insulating property of the oxide layer is lowered, thereby lowering the surface resistance. Accordingly, the oxide layers on the surface of the soft magnetic composite material of the foregoing Examples 3-1 and 3-2 have better resistance to high molding pressure.

According to the content shown in FIG. 5, when the mixing time of the phosphorus glass sol and the iron-based soft magnetic powder is increased, the thickness of the phosphorus glass phase of the soft magnetic composite material is increased, and the denseness of the oxide film is also The increase can increase the surface impedance of the soft magnetic composite material. However, when the insulating property of the oxide film on the surface of the soft magnetic composite material is increased, the magnetic properties of the soft magnetic composite material are affected, and the application thereof is lowered.

Accordingly, in order to achieve both the magnetic properties and the insulating properties of the soft magnetic composite material, the mixing time of the phosphorus glass sol of the present invention and the iron-based soft magnetic powder is preferably 30 minutes.

Example 4-1 to Example 4-3

Each of Examples 4-1 to 4-3 was subjected to measurement of saturation magnetic flux density using a square test piece prepared in the foregoing Example 3-1 to Example 3-3, wherein the molding pressure was 1000 MPa. The results are shown in Figure 6, respectively.

Example 4-4

First, 40 weight percent aqueous phosphoric acid (H ₃ PO ₄ ) and tetraethoxysilane were prepared as reactants having an equivalent ratio of 1:2. Then, the sol-gel reaction was carried out at 60 ° C, and after 1 hour, a phosphorus glass sol was obtained.

Next, based on the iron-based soft magnetic powder used in an amount of 100% by weight, 10 parts by weight of the phosphorus glass sol and the iron-based soft magnetic powder are mixed by vertical mechanical stirring or horizontal uniaxial double-helical mechanical stirring, and further added 2 The weight percent of calcium stearate is stirred and mixed. After mixing for 1 hour, The soft magnetic composite material of Example 4-4 was obtained by drying at 200 ° C and sieving at 80 mesh.

Then, 1 g of the aforementioned soft magnetic composite material was taken and molded at a molding pressure of 1000 MPa to form square test pieces having a length and width of 7.1 mm and 9.6 mm, respectively. The obtained square test piece was subjected to measurement of saturation magnetic flux density, and the results are shown in Fig. 6.

Example 4-5

Example 4-5 used the same manufacturing method as that of the magnetic core of Example 4-4, except that Examples 4-5 changed the ratio of the reactants. The ratio of the equivalents of the aqueous phosphoric acid solution to the tetraethoxy decane of Example 4-5 was 1:2. The obtained square test piece was subjected to measurement of saturation magnetic flux density, and the results are shown in Fig. 6.

Comparative Example 4-1

First, 40% by weight of sodium citrate stock solution (Na ₂ O‧nSiO ₂ ‧xH ₂ O; n=2.8 to 3.3; Na ₂ O: 8 to 10%; and SiO ₂ : 23 to 30%) Ionized water was diluted to prepare a sodium citrate salt sol having a volume ratio of 1:1.

Next, based on the iron-based soft magnetic powder used in an amount of 100% by weight, the 3 parts by weight of the phosphorus glass sol and the iron-based soft magnetic powder are mixed by vertical mechanical stirring or horizontal uniaxial double-helical mechanical stirring, and further added 2 The weight percent of calcium stearate is stirred and mixed. After mixing for 1 hour, it was dried at 200 ° C and sieved at 80 mesh to obtain a soft magnetic composite material of Comparative Example 4-1.

Then, 1 g of the aforementioned soft magnetic composite material was taken and molded at a molding pressure of 1000 MPa to form square test pieces having a length and width of 7.1 mm and 9.6 mm, respectively. The obtained square test piece was subjected to measurement of saturation magnetic flux density, and the results are shown in Fig. 6.

Please refer to FIG. 6 , which is a graph showing changes in the saturation magnetic flux density versus the equivalent ratio of phosphoric acid to decane according to Examples 4-1 to 4-5 and Comparative Example 4-1 of the present invention, wherein the X-axis represents The equivalent ratio of phosphoric acid to decane and the mixing time of the phosphorus glass sol and the iron-based soft magnetic powder, and the Y axis represents the saturation magnetic flux density in units of emu/g.

In Fig. 6, when the equivalent ratio of phosphoric acid to decane is 1:1, and the mixing time of the phosphor glass sol and the iron-based soft magnetic powder is 30 minutes, the obtained square test piece has a small saturation magnetic flux density. Variety. Accordingly, the soft magnetic composite material of the present invention is preferably subjected to a lyotropic reaction using a reactant having an equivalent ratio of phosphoric acid to decane of 1:1, and the mixing time of the formed phosphor glass sol and the iron-based soft magnetic powder is compared. Good for 30 minutes.

Example 5-1

Example 5-1 Example 3-1 using the aforementioned system prepared embodiments of the square test piece for permeability (μ _e) and iron loss (P _CV) of the measurement, wherein a molding pressure of 1000MPa. The results are shown in Figures 7a and 7b, respectively.

Comparative Example 5-1

In Comparative Example 5-1, the soft magnetic composite material of Comparative Example 2-2 was weighed. Then, the soft magnetic composite material is molded at a pressure of 1000 MPa to make Square test pieces with a length and width of 7.1 mm and 9.6 mm, respectively. Then, the magnetic permeability and iron loss of the square test piece were measured. The results are shown in Figures 7a and 7b, respectively.

Comparative Example 5-2 and Comparative Example 5-3

In Comparative Example 5-2 and Comparative Example 5-3, a soft magnetic composite material was produced by the same production method as Comparative Example 1-1 except that the use amount of the sodium citrate stock solution of Comparative Example 5-2 was 3 weight%, and comparison was made. The sodium citrate stock solution of Example 5-3 was used in an amount of 6 wt%.

Next, the soft magnetic composite material was weighed and the soft magnetic composite material was molded at a pressure of 1000 MPa to obtain square test pieces having a length and width of 7.1 mm and 9.6 mm, respectively. Then, the magnetic permeability and iron loss of the square test piece were measured. The results are shown in Figures 7a and 7b, respectively.

Please refer to FIG. 7a and FIG. 7b, which respectively show changes in magnetic permeability or iron loss according to Embodiment 5-1 and Comparative Example 5-1 to Comparative Example 5-3 of the present invention, wherein the X-axis represents Embodiment 5 -1 and Comparative Example 5-1 to Comparative Example 5-3, and the Y-axis represents magnetic permeability (Fig. 7a), which is a dimensionless unit (μ = 1 = 4 π × 10 ^-7 H/m), or iron Loss (Fig. 7b), the unit is kW/m ³ .

Since the oxide film on the surface of the soft magnetic composite material of Embodiment 5-1 is mainly phosphorus glass, and the phosphorus glass has a good coating and the compactness thereof is relatively high, the soft magnetic composite material of Example 5-1 has a high conductivity. Magnetic rate and lower iron loss (about 800 kW/m ³ ).

However, in Comparative Example 5-1, the soft magnetic composite material obtained by the conventional phosphating treatment had a lower magnetic permeability and a higher iron loss (about 1000 to 1100 kW/m ³ ). The reason is that when the soft magnetic composite material is molded at a molding pressure of not less than 1000 MPa and heat treatment is performed at a high temperature of 760 ° C, the high pressure and high temperature treatment means destroy the phosphate film on the surface of the soft magnetic composite material, thereby making the soft magnetic composite material The magnetic permeability is lowered and the iron loss is increased.

In Comparative Example 5-2 and Comparative Example 5-3, as the amount of sodium citrate used was increased, the water glass insulating phase of the surface of the soft magnetic composite material produced was increased. However, the iron loss of the prepared soft magnetic composite material did not increase, and the magnetic permeability thereof decreased (about from 61 to 45). The reason is that the content of the non-magnetic medium (that is, the water glass insulating phase) is increased, so that the magnetic permeability of the soft magnetic composite material is lowered.

Example 6

In Example 6, a magnetic core was produced by using the soft magnetic composite material obtained in Example 3-1, wherein the molding pressure of the molding was 1000 MPa, and the temperature of the heat treatment step was 760 °C. The prepared hollow cylindrical magnetic core was cut along the central axis of the cylindrical magnetic core, and the cut surface of the magnetic core was observed by SEM and Electron Probe X-ray MicroAnalyzer (EPMA). The result is shown in Figure 8a.

Comparative Example 6

In Comparative Example 6, a magnetic core was produced by using the soft magnetic composite material obtained in Comparative Example 5-3, wherein the molding pressure was 1000 MPa, and the temperature of the heat treatment step was 760 °C. The hollow cylindrical core is cut along the central axis of the cylindrical core, and the SEM and electronic micro-survey (Electron Probe X-ray MicroAnalyzer; EPMA) Observe the cut surface of the core. The result is shown in Figure 8b.

Referring to FIGS. 8a and 8b, there are shown SEM and EPMA views, respectively, of the cross-sections of the magnetic cores according to Example 6 and Comparative Example 6 of the present invention. Wherein, (1) of each figure respectively shows an SEM image of the magnetic core; (2) of each figure shows an EPMA diagram of a phosphorus atom or a sodium atom of the SEM image of FIG. 8a (1) and FIG. 8b (1), respectively; (3) of each figure shows the EPMA map of the oxygen atom of the SEM image of Fig. 8a (1) and Fig. 8b (1), respectively. The magnification of the SEM image of (1) of each figure is 10000 times, and the length of the scale rule of (2) and (3) of each figure represents 20 micrometers.

According to the contents shown in FIG. 8a (1) and FIG. 8b (1), after the soft magnetic composite material of the magnetic core obtained in Embodiment 6 is formed by high pressure and high temperature, the soft magnetic composite material is still a continuous phase. Therefore, it can be seen that the magnetic core produced by the invention can have a high magnetic permeability and a low iron loss. However, the soft magnetic composite material of the magnetic core prepared in Comparative Example 6 was not subjected to a continuous phase after high pressure high temperature molding. Furthermore, the surface roughness of the iron-based soft magnetic powder is large, so that the water glass insulation coating layer cannot form a uniform coating layer, thereby reducing the continuity thereof, thereby reducing the high molding pressure strength of the water glass insulation coating layer.

Accordingly, when the soft magnetic composite material used in Comparative Example 6 is subjected to high pressure molding, the formed water glass insulating coating layer is destroyed, so that the soft magnetic composite material is not a continuous phase.

Next, according to the EPMA diagrams of the phosphorus atom or the sodium atom and the oxygen atom shown in Fig. 8a (2) to Fig. 8a (3) and Fig. 8b (2) to Fig. 8b (3), The surface of the magnetic core produced by the invention has a relatively uniform insulating oxide film, so the magnetic core and soft magnetic composite material of the present invention should have better magnetic properties and insulating properties. In addition, the soft magnetic composite material of the invention also has better resistance to high molding pressure and thermal stability, and can form a relatively uniform and dense insulating oxide film on the surface of the iron-based soft magnetic powder, thereby improving the magnetic core produced. Magnetic properties.

According to the foregoing embodiments, the soft magnetic composite material prepared by the invention can form a relatively uniform and dense oxide insulating film, and can form a displacement coating reaction with the surface of the iron-based soft magnetic powder, and is formed uniformly. The dense oxidized insulating film further enhances the magnetic properties of the magnetic core obtained by molding.

Secondly, the soft magnetic composite material obtained has better resistance to high molding pressure and thermal stability, so the soft magnetic composite material can withstand the high molding pressure and high temperature heat treatment of the magnetic core, and can form a continuous oxidation insulating film, and further Improve the magnetic properties of the resulting magnetic core.

Furthermore, since the soft magnetic composite material produced by the present invention has better high molding pressure resistance, it can withstand higher molding pressure. Therefore, by increasing the molding pressure, the present invention can produce a magnetic core having a high magnetic permeability and achieve a high response rate.

In addition, since the soft magnetic composite material prepared by the invention can form a uniform and dense oxide insulating film, the soft magnetic composite material can be used to obtain a magnetic core having good magnetic properties, and the magnetic core can be operated under high frequency operation. The eddy current effect is effectively suppressed, and the performance of the magnetic core is prevented from being lowered, and the heat energy generated by the eddy current is avoided.

The present invention has been disclosed in the above embodiments, and is not intended to limit the present invention. Any one of ordinary skill in the art to which the present invention pertains can make various changes without departing from the spirit and scope of the invention. The scope of protection of the present invention is therefore defined by the scope of the appended claims.

100‧‧‧ method

110‧‧‧Procedures for providing precursor mixtures

120‧‧‧Steps of mixing phosphorus glass sol and iron-based soft magnetic powder

130‧‧‧Steps for sol-gel reaction of precursor mixtures

140‧‧‧Steps of drying and mixing the phosphorous glass sol and the iron-based soft magnetic powder

150‧‧‧Steps for making soft magnetic composites

Claims (10)

A method for producing a soft magnetic composite material, comprising: providing a precursor mixture, wherein the precursor mixture comprises a reactant and an organic solvent, and the reactant comprises a phosphoric acid compound and a decane monomer; and the total amount of the reactant based on the reactant is 100% by mole, one of the phosphate compounds is used in an amount from 20 mole percent to 66 mole percent, and one of the decane monomers is used in an amount from 34 mole percent to 80 mole percent; based on one of the precursor mixtures The amount used is 100% by weight, one of the reactants is used in an amount of 10% by weight to 50% by weight, and one of the organic solvents is used in an amount of 50% by weight to 90% by weight; a sol-gel reaction is performed on the precursor mixture. Wherein the lyogel reaction is carried out at 60 ° C to 80 ° C for 30 minutes to 60 minutes to obtain a phosphorous glass sol; and the phosphor glass sol and an iron-based soft magnetic powder are mixed at 100 ° C to 300 ° C The soft magnetic composite material is obtained by drying for 1 hour to 2 hours, wherein one of the phosphorus glass sol and the iron-based soft magnetic powder is mixed for 10 minutes to 60 minutes. The method for producing a soft magnetic composite material according to claim 1, wherein the phosphoric acid compound comprises inorganic phosphoric acid, organic phosphoric acid or organic phosphate. The method for producing a soft magnetic composite material according to claim 1, wherein the iron-based soft magnetic powder has a particle diameter of 25 μm to 250 μm. The method for producing a soft magnetic composite material according to claim 1, wherein the lyogel reaction is carried out for 60 minutes. A soft magnetic composite material produced by the manufacturing method according to any one of claims 1 to 4, wherein the soft magnetic composite material comprises a phosphorus glass phase, and the weight is 100 weight based on one of the soft magnetic composite materials. As a percentage, one of the phosphorus glass phases is contained in an amount of from 0.1% by weight to 2% by weight. A method for manufacturing a magnetic core, comprising: forming a soft magnetic composite material according to a molding pressure of at least 800 MPa to form an embryo body; and subjecting the embryo body to a heat treatment Steps to form the magnetic core, wherein the heat treatment step is performed at 700 ° C to 800 ° C for 30 minutes to 60 minutes. The method for manufacturing a magnetic core according to claim 6, wherein before the forming step, the method further comprises: A lubricant is added to the soft magnetic composite material, wherein one of the lubricants is used in an amount of from 0.5% by weight to 5% by weight based on 100% by weight of the iron-based soft magnetic powder. The method for manufacturing a magnetic core according to claim 6, wherein the molding pressure is 800 MPa to 1400 MPa. The method of manufacturing a magnetic core according to claim 6, wherein the embryo system performs the heat treatment step in an inert gas. A magnetic core produced by the method of any one of claims 6 to 9 and having an insulation resistance value of not less than 10 ⁹ Ω.