KR101640561B1 - A manufacturing method of a magnetic core and an inductor with an embedded coil by molding process under a room temperature condition and a magnetic core and a molded inductor manufactured thereby. - Google Patents

Abstract

The present invention relates to a method of manufacturing a magnetic core and a coil-embedded type inductor, which improves workability and productivity and improves the behavior characteristics of a magnetic core and a coil-embedded type inductor manufactured through the molding process at room temperature, , Wherein at least one of a hardener and a curing accelerator is added to the magnetic powder paste, mixing and degassing to produce a molding member, and a part of the coil and the electrode are placed inside the cast having a predetermined shape A step of injecting a molding member into a cast, molding the molding member for a predetermined time to mold the magnetic core, and taking out a coil-embedded inductor including the magnetic core from the cast. A method of manufacturing a coil-embedded type inductor using a magnetic powder paste at room temperature.

Description

Technical Field The present invention relates to a method for manufacturing a magnetic core and a coil-embedded type inductor at room temperature, and a magnetic core and a coil-embedded type inductor manufactured using the method. and a molded inductor manufactured thereby.

The present invention relates to a magnetic core and a method of manufacturing a coil-embedded type inductor by molding at room temperature, and more particularly, to a method of manufacturing a magnetic core and a coil- A method of fabricating a magnetic core and a coil-embedded type inductor, which improves the behavior characteristics of the coil-embedded type inductor, is provided.

In Korean Patent No. 10-1369109 entitled " Compressed Magnetic Core Manufacturing Method and Compressed Magnetic Core Obtained by the Manufacturing Method, hereinafter referred to as Prior Art 1 "), an insulating film is formed on the surface of the iron- A method for producing a compacted green compact according to any one of claims 1 to 3, characterized by comprising: a molding step of obtaining a green compact by compression molding a mixture containing iron soft magnetic powder for a compacted green body and an oxygen radical releasing compound; heating the compacted green compact at 200 ° C to 700 ° C And a heat treatment step of oxidizing the surface of the iron-based soft magnetic powder.

KR 10-1369109 B1

The prior art 1 requires a high-pressure press process in which expensive equipment is required, and a problem that a core loss becomes large due to internal stress generated in the magnetic core particles during pressurization have. Furthermore, there is a problem that the process time is increased due to the annealing process or the like necessary for removing the internal stress and the productivity is lowered.

Adding at least one of a hardener and a hardening accelerator to the magnetic powder paste to prepare a molding member by mixing and degassing, injecting the molding member into a cast having a predetermined shape, Forming a magnetic core by curing the magnetic core for a predetermined period of time, and taking out the magnetic core from the cast. The present invention also provides a method of manufacturing a magnetic core using the magnetic powder paste.

Also, at least one of a curing agent and a curing accelerator is added to the magnetic powder paste, mixing and degassing to produce a molding member, a part of the coil and the electrode are placed inside the cast having a predetermined shape, A step of injecting a member into a casting, curing the molding member for a predetermined time to mold the magnetic core, and taking out a coil-embedded inductor including the magnetic core from the casting. A method of manufacturing a coil-embedded inductor using a powder paste is provided.

The manufacturing method of the present invention is a first effect that when a device or device such as a magnetic core or a coil-embedded type inductor is manufactured by using the first effect, a performance factor required for the device or the device can be satisfied; The ceramic coating of the particles, the pressing process for increasing the density of the magnetic core, and the like are unnecessary, thereby reducing the manufacturing cost. In addition, since the annealing process at a high temperature is not required, the third effect that there is no fear that the film of the buried coil is deteriorated, and the fourth effect of the productivity increase due to the simplification of the process such as omitting the annealing process do.

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

With regard to the second effect, there is no need for an expensive high-pressure press, which is essential in the conventional production process of the pressurized core, and the internal stress generated in the magnetic core particles during the pressurization process is not a problem, And an annealing process for removing such internal stress is unnecessary.

1 (a) is a perspective view showing an embodiment of a coil-embedded type inductor manufactured using the method of the present invention.
Fig. 1 (b) shows a coil (bus bar type) coil-embedded type inductor manufactured by the method of the present invention.
And Fig.
1 (c) is a cross-sectional view taken along line A-A 'in an embodiment of a coil-embedded inductor manufactured using the method of the present invention.
2 (a) is a perspective view showing an embodiment of a bobbin-equipped coil-embedded type inductor manufactured by the method of the present invention.
Fig. 2 (b) is a perspective view showing an embodiment of a coil (having a circular section) of a bobbin-equipped coil-embedded inductor manufactured using the method of the present invention.
FIG. 2 (c) is a cross-sectional view taken along the line B-B 'in one embodiment of a bobbin-equipped coil-embedded type inductor manufactured by the method of the present invention.

A method of manufacturing a magnetic core using the magnetic powder paste of the present invention will be described.

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.

A magnetic powder paste, an organic vehicle made of a polymer resin, and a magnetic powder. However, in order to manufacture the magnetic core or the coil-embedded type inductor by the molding under room temperature, the composition ratio should be determined so as to satisfy the required flowability, curability and magnetic characteristics.

First, at least one selected from the group consisting of a hardener and a hardening accelerator is added to the magnetic powder paste. Examples of the curing agent include aliphatic amines such as amines, modified aliphatic amines, aromatic amines, modified aromatic amines, acid anhydrides, polyamides, imidazoles and the like. Examples of the curing accelerator include Lewis acids, alcohols, phenols, Imidazoles, and the like, and the time required for natural curing can be reduced through the use thereof.

Second, the mixture from the first step is mixed and degassed to produce a molding member. In order for the above-mentioned curing agent, curing accelerator, etc. to function uniformly over the entire volume of the paste, mixing is required. For such mixing, a rotary stirrer or a planetary stirrer can be used. The defoaming is to remove the bubbles contained in the magnetic powder paste. Through such a bubble removing process, not only the permeability can be increased but also the strength of the magnetic core to be formed later can be increased.

Third, the molding member is injected into a cast having a predetermined shape. The shape of the cast is formed in accordance with the shape of the target magnetic core. In one embodiment, the shape of the cast may be a rod shape such as a rectangular parallelepiped or a shape obtained by chamfering the corner of the rectangular parallelepiped. As an embodiment of this injection, it may simply be a method of putting the molding member in a tube and discharging from the top of the cast, or an automated method using a dispenser may be used. The casting may be a mold which is not deformed even under a high pressure. In this case, a known injection molding machine may be used. Can be applied.

Fourth, the injected molding member is cured for a predetermined time to mold the magnetic core. In this curing process, heat treatment at a predetermined temperature may be considered, which is called curing, and the curing time can be further reduced. It is recommended that the heat treatment temperature is 100 to 200 degrees Celsius, and the heat treatment may be performed after the extraction process from the casting, which will be described later. This is different from the annealing process included in a conventional pressurized core manufacturing process. Since the application temperature is lower than that in the annealing process and the purpose is to increase the hardening rate, the object of the annealing process is to form magnetic particles Which is the difference between the two. In this curing process, the volume of the magnetic core may be reduced due to the volatilization of the organic solvent contained in the paste, and this phenomenon is considered to be increased as the content of the organic vehicle is higher.

Fifth, the magnetic core formed in the previous stage is taken out from the cast.

Next, a method for manufacturing a coil-embedded inductor having a structure in which a coil is embedded in a magnetic core using a magnetic powder paste will be described.

When the coils among the inductors are integrally formed by embedding them in the magnetic core, the magnetic effective sectional area can be maximized and a high inductance can be obtained. In addition, it is possible to compensate for the disadvantages of the winding process of the toroidal core, the performance degradation due to the air gap of the separable-assembled core, and the induction heating phenomenon. FIG. 1 shows an embodiment of a coil-embedded type inductor manufactured using the manufacturing method of the present invention. FIG. 1 (b) shows an embodiment of a coil (manufactured using a bus bar) to be embedded.

As a first step of the manufacturing method, at least one selected from a curing agent and a curing accelerator is added to the magnetic powder paste. As the curing agent, at least one selected from the group consisting of an acid anhydride system, amine system, imidazole system and amide system can be selected. As the curing accelerator, at least one selected from the group consisting of Lewis acid, alcohol, phenol and carboxylic acid can be selected have.

Second, the molding material is prepared by mixing and degassing the mixture from the first step. In order for the curing agent, the curing accelerator, and the like to function uniformly over the entire volume of the paste, mixing is required. For such mixing, a rotary stirrer or a high viscosity blender may be used. The defoaming is to remove the bubbles contained in the magnetic powder paste. Through such a bubble removing process, not only the permeability can be increased but also the strength of the magnetic core to be formed later can be increased.

Third, a part of the coil is disposed inside the cast of a predetermined shape. Most of the coils are embedded in the magnetic core, while the remaining portions are exposed to the outside of the magnetic core to serve as external terminals (electrodes). Of course, it is also possible to consider a constitution in which a part serving as such an external terminal is provided as a separate member and is electrically connected to the coil. In an embodiment of the coil shown in FIG. 1 (b), the coil is directly provided as an electrode without providing an additional electrode. Since the casting is formed in the shape of a magnetic core, the casting must be designed in consideration of this, and a casting structure is required in which the coil and the electrode are fixed so that the position and position of the coil and the electrode, .

Fourth, the molded member is injected into a cast having a predetermined shape. As an embodiment of this injection, it may simply be a method of putting the molding member in a tube and discharging from the top of the cast, or an automated method using a dispenser may be used. The casting may be a mold which is not deformed even under a high pressure. In this case, a known injection molding machine is applied (for example, can do.

Fifth, the injected molding member is cured for a predetermined time to mold the magnetic core. In this curing process, heat treatment at a predetermined temperature may be considered. This is called curing, and the curing time can be further reduced through the curing. Such a heat treatment may be performed after a taking-out process from a cast which will be described later. Fifth, the magnetic core formed in the previous stage is taken out from the cast. In the embodiment of FIG. 1, the magnetic core thus manufactured and the coil embedded therein are inserted into the case 120 to complete the coil-embedded inductor.

Next, a method of manufacturing a bobbin-equipped coil-embedded type inductor having a structure in which a magnetic powder paste is used and a bobbin and a coil are embedded in a magnetic core will be described.

Fig. 2 shows an embodiment of a bobbin-equipped coil-embedded type inductor manufactured using the manufacturing method of the present invention. Particularly, Fig. 1 (b) shows a coil (having an annular cross section, ) Is shown.

As a first step of the manufacturing method, at least one selected from a curing agent and a curing accelerator is added to the magnetic powder paste. As the curing agent, at least one selected from the group consisting of an acid anhydride system, amine system, imidazole system and amide system can be selected. As the curing accelerator, at least one selected from the group consisting of Lewis acid, alcohol, phenol and carboxylic acid can be selected have.

Second, the molding material is prepared by mixing and degassing the mixture from the first step. In order for the curing agent, the curing accelerator, and the like to function uniformly over the entire volume of the paste, mixing is required. For such mixing, a rotary stirrer or a high viscosity blender may be used. The defoaming is to remove the bubbles contained in the magnetic powder paste. Through such a bubble removing process, not only the permeability can be increased but also the strength of the magnetic core to be formed later can be increased.

Third, the coil is prepared in a state of being wound around the bobbin, and a part of the coil and the bobbin are disposed inside the cast having a predetermined shape. Most of the coils are embedded in the magnetic core, while the remaining portions are exposed to the outside of the magnetic core to serve as external terminals (electrodes). Of course, it is also possible to consider a constitution in which a part serving as such an external terminal is provided as a separate member and is electrically connected to the coil. In the embodiment shown in FIG. 2 (b), the coil is directly provided as an electrode without providing an additional electrode. Since the casting is formed in the shape of a magnetic core, the casting must be designed in consideration of this, and a casting structure is required in which the coil and the electrode are fixed so that the position and position of the coil and the electrode, . In the embodiment of the coil shown in FIG. 2 (c), a coil having a circular cross section is wound around the bobbin, but the bobbin can be formed by coupling the two parts 220a and 220b, A coil formed in an annular shape is inserted between the two parts to form a bobbin and a coil assembly, but the configuration is not limited thereto. That is, it means that a process of winding the coil directly on the bobbin may be performed.

Fourth, the molded member is injected into a cast having a predetermined shape. As an embodiment of this injection, it may simply be a method of putting the molding member in a tube and discharging from the top of the cast, or an automated method using a dispenser may be used. The casting may be a mold which is not deformed even under a high pressure. In this case, a known injection molding machine is applied (for example, can do.

Fifth, the injected molding member is cured for a predetermined time to mold the magnetic core. In this curing process, heat treatment at a predetermined temperature may be considered. This is called curing, and the curing time can be further reduced through the curing. Such a heat treatment may be performed after a taking-out process from a cast which will be described later. Fifth, the magnetic core formed in the previous stage is taken out from the cast. In the embodiment of FIG. 2, the coil and the bobbin buried in the magnetic core thus manufactured are inserted into the cases 250a and 250b to complete a coil-embedded inductor having a bobbin.

[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.

100: Coil buried inductor
110: Coil (bus bar type)
130: magnetic core
140: Case


200: Bobbin-equipped type coil-embedded inductor
210: coil (annular)
220a: first bobbin part
220b: second bobbin part
230: magnetic core

250a: first casing part
250b: a second casing part

Claims (12)

A method of manufacturing a magnetic core using a magnetic powder paste,
(a) providing a mixture (s10) by adding at least one of a curing agent and a curing accelerator to a magnetic powder paste having a density of 3.0 to 6.0 g / cc;
(b) mixing and degassing the mixture in step (a) at room temperature to produce a molding member (s20);
(c) injecting (molding) the molding member which has been mixed and defoamed at room temperature in step (b) into a cast having a predetermined shape (s30);
(d) molding the magnetic core by curing the molding member injected in the step (c) for a predetermined time (s40);
(e) a step (s500) of taking out the magnetic core formed in the step (d) from the cast;
The method of manufacturing a magnetic core using the magnetic powder paste according to claim 1, The method according to claim 1,
Wherein the heat treatment is performed at a predetermined temperature in order to increase a curing rate during the curing step in the step (d). The method according to claim 1,
Wherein the injection of the step (c) is performed by a metal powder injection molding process. A magnetic core produced by the method of any one of claims 1 to 3. A method of manufacturing a coil-embedded type inductor having a structure in which a coil is embedded in a magnetic core using a magnetic powder paste,
(I) adding (s100) at least one of a curing agent and a curing accelerator to a magnetic powder paste having a density of 3.0 to 6.0 g / cc;
(II) mixing and degassing the mixture in step (I) at room temperature to produce a molding member (s200);
(III) disposing a part of the coil inside the cast of a predetermined shape (s300);
(IV) injecting the molding member manufactured in the step (II) into the cast (s400);
(V5) molding the magnetic core by sintering the molding member injected in the step (IV) for a predetermined time (s500);
(VI) extracting a coil-embedded inductor including the magnetic core formed in the step (V) from the cast (s600);
Wherein the magnetic powder paste is used for forming a coil-embedded type inductor. The method of claim 5,
Wherein the molding material is heat-treated at a predetermined temperature in order to increase a curing rate during the curing process in the step (V). The method of claim 5,
Wherein the injection of the step (IV) is performed by a metal powder injection molding process. A coil-embedded inductor produced by the method according to any one of claims 5 to 7. A method of manufacturing a coil-embedded inductor with a bobbin having a structure in which a bobbin and a coil are embedded in a magnetic core using a magnetic powder paste,
(1) adding at least one of a hardener and a hardening accelerator to a magnetic powder paste having a density of 3.0 to 6.0 g / cc (s1000);
(2) mixing and degassing the mixture in the step (1) at room temperature to produce a molding member (s2000);
(3) a step (s3000) of preparing the coil in a state that the coil is wound on the bobbin, and placing a part of the coil and the bobbin inside a cast having a predetermined shape;
(4) injecting the molding member manufactured in the step (2) into the cast (S4000);
(5) molding the magnetic core by curing the molding member injected in the step (4) for a predetermined time (s5000);
(6) A step (s6000) of extracting a coil-embedded inductor having a bobbin including the magnetic core formed in the step (5) from the cast (s6000);
Wherein the magnetic powder paste is used for forming a bobbin-equipped coil-embedded type inductor. The method of claim 9,
Wherein the molding member is heat-treated at a predetermined temperature in order to increase a curing rate during the curing process in the step (5). The method of manufacturing a molded-in-bobbin-type inductor according to claim 1, The method of claim 9,
Wherein the step (4) is performed by a metal powder injection molding process. The method of manufacturing a molded-in-bobbin-type inductor according to claim 1, A coil-embedded inductor with a bobbin manufactured by the method according to any one of claims 9 to 11.

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