KR102126062B1 - Soft magnetic composites and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a soft magnetic composite material and a manufacturing method thereof. The manufacturing method comprises: a step of manufacturing an epoxy resin solution comprising 80-96 mass% of soft magnetic powder, 2-10 mass% of epoxy resin powder, 0.1-5 mass% of a hardener, and 1-5 mass% of a removing agent by dissolving the epoxy resin powder in an organic solvent; a step of manufacturing a soft magnetic mixture by mixing the soft magnetic powder and the removing agent; a step of mixing and stirring the epoxy resin solution and the soft magnetic mixture to make slurry; and a step of injecting the slurry into a mold and heating and pressurizing at 150-180°C to manufacture a formed body. The present invention can provide a formed body of a soft magnetic composite material which facilitates size adjustment, simplifies a manufacturing process to increase productivity, and minimizes property degradation.

Description

SOFT MAGNETIC COMPOSITES AND MANUFACTURING METHOD THEREOF}

The present invention relates to a soft magnetic composite material and a method of manufacturing the same, and more particularly, to a soft magnetic composite material applied to an electronic device such as an inductor and a method of manufacturing the same.

An inductor is a device that converts and stores electrical energy into magnetic energy. The inductor has a characteristic of preventing passage of alternating current and smoothly passing direct current.

As shown in FIG. 1, the inductor 10 wraps the inner core 13 where the terminal pin 11 is assembled, the coil 15 wound on the inner core 13, and the coil 15, and the inner core ( 13) It includes an outer core (17) assembled to. The inner core 13 and the outer core 17 are manufactured by compression molding a magnetic powder bonded with paraffin and then sintering it in a high temperature furnace. As the magnetic powder, nickel zinc ferrite is used.

The manufactured inner core 13 winds the coil 15, combines it with the outer core 17, and heat-seals it using a thermosetting resin 19.

The inductor 10 manufactured by the above method has a high magnetic conductivity since the inner core 13 and the outer core 17 are made of nickel zinc ferrite, but due to the shrinkage of the thermosetting resin, the sealing property is poor and self-leakage occurs. In the production process, energy consumption is high and pollution is a serious problem.

Recently, electromagnetic materials for injection molding by mixing thermosetting resin and iron powder have also been developed. Injection molding is advantageous in that the process is simple and the production efficiency is high compared to the manufacturing of the inner core and the outer core by the aforementioned sintering method. However, the thermosetting resin has a problem that the curing shrinkage is relatively large, pores are easily generated inside, and the consistency of the molded product is relatively low.

It is an object of the present invention to provide a soft magnetic composite material for injection molding and a method for manufacturing the injection molding which is easy to adjust the size and simplifies the manufacturing process to increase productivity and minimizes property degradation.

According to the features of the present invention for achieving the above object, the present invention is a soft magnetic powder 80 mass% ~ 96 mass%, epoxy resin powder 2 mass% ~ 10 mass%, curing agent 0.1 mass% ~ 5 mass%, 1% by mass to 5% by mass of the release agent.

The soft magnetic powder is manganese zinc ferrite powder.

The soft magnetic powder has a particle size of d50≤50㎛.

The epoxy resin powder has a particle size of d90≤10㎛, and an epoxy value (equivalent/100g) of 0.09 to 0.14.

The curing agent is an amine-based curing agent.

The demoulding agent is zinc stearate.

Dissolving an epoxy resin powder and a curing agent in an organic solvent to prepare an epoxy resin solution and mixing a soft magnetic powder with a demoulding agent to prepare a soft magnetic mixture, mixing the epoxy resin solution with the soft magnetic mixture, and stirring the mixture. And a step of making a slurry and injecting the slurry into a mold and heating and pressurizing to 150 to 180°C to prepare a molded body.

After the step of making the slurry, before the step of injecting the slurry into the mold,

The slurry is vacuum dried at a temperature of 40 to 60° C. for 2 to 4 hours to further remove the solvent.

Since the soft magnetic composite material of the present invention can be injection molded, it has a low strain rate compared to the plastic material, so that it can be precisely dimensioned, and because it is not a crystalline structure, it is a combined structure, so it is resistant to physical shock or thermal shock, and it is easy to adjust its size, so It is possible to implement, the vibration noise is reduced, the internal noise characteristics are improved, and the manufacturing process is simplified to increase productivity.

In addition, since the soft magnetic composite material of the present invention is a soft magnetic powder, it is possible to injection molding by mixing manganese zinc ferrite powder with an epoxy resin powder, which is an injection material, thereby significantly reducing quality and cost while minimizing property degradation. .

1 is a view showing an example of a conventional inductor,
2 and 3 is a cross-sectional view showing an example of an inductor manufactured using the soft magnetic composite material of the present invention,
Figure 4 is a process diagram showing a method of manufacturing a soft magnetic composite material of the present invention,
5 is a photograph showing an example of various shapes of an inductor manufactured using the soft magnetic composite material of the present invention,
6 is a view for explaining the driving of FIG. 5(c).

Hereinafter, embodiments of the present invention will be described in detail.

The soft magnetic composite material of the present invention is an injection molded molded body. The molded body may be an inner core of an inductor (inductor element).

As electronic devices are gradually miniaturized and integrated, the demand for the electromagnetic wave shielding effect of the inductor is increasing day by day, and the demand for product size and shape is also gradually increasing. Besides, the inner core of the inductor has a high demand for product insulation, and the outer core must be insulated on the surface to satisfy the demand for use. In addition to the structural design, the inductor's shielding effect is significantly related to its unique magnetic powder shape. The electronic device includes a soft magnetic composite material as a core material, and the core may be an inner core of the inductor.

The soft magnetic composite material of the present invention is a material capable of injection molding. The material that can be injection molded can be manufactured in a large size because it is easy to adjust the size compared to the sintered material, and since it does not sinter, the property deterioration is minimized and the manufacturing process is simplified to increase productivity.

Soft magnetic composite materials include soft magnetic powders, epoxy resins, curing agents, and demoulding agents. Specifically, the soft magnetic composite material includes 80 to 96 mass% of soft magnetic powder, 2 to 10 mass% of epoxy resin powder, 0.1 to 5 mass% of curing agent, and 1 to 5 mass% of release agent.

The soft magnetic powder provides soft magnetic properties to the entire soft magnetic composite material and imparts characteristics such as electromagnetic wave absorption and shielding. The soft magnetic powder contains 80 to 96 mass% of the total mass of the soft magnetic composite material.

When the soft magnetic powder is contained in an amount of less than 80% by mass relative to the total mass of the soft magnetic composite material, the magnetic powder has a volume fraction of only 42%, so its content is too small and it is difficult to form a magnetic network connected to the epoxy resin. It is difficult for the magnetic composite material to act as an electromagnetic shield.

When the soft magnetic powder reaches 96% by mass relative to the total mass of the soft magnetic composite material, the magnetic powder content of the soft magnetic composite material reaches the limit and a complete magnetic network is formed in it, and the permeability (μi) reaches 500 at the maximum. do. However, if the content of the soft magnetic powder is continuously increased in excess of 96 mass%, the fluidity of the soft magnetic composite material is deteriorated, resulting in loss of molding processability and an increase in permeability.

The epoxy resin powder combines the soft magnetic powder to impart structural characteristics and molding processing characteristics of the soft magnetic composite material. The manganese zinc ferrite powder, which is a soft magnetic material, is mixed with an epoxy resin powder, which is an injection material, to enable injection molding. Injection molding enables the production of products of various shapes, not limited to size.

The epoxy resin powder contains 2 to 10% by mass relative to the total mass of the soft magnetic composite material. When the epoxy resin powder is contained in an amount of less than 2% by mass, the content of the soft magnetic powder in the total soft magnetic composite powder is relatively high, and thus it is difficult to mold the soft magnetic powder because it does not serve to bond the soft magnetic powder. However, when the epoxy resin powder is contained in excess of 10% by mass, the content of the soft magnetic powder is too low to form a magnetic network, and thus it is difficult to serve as an electromagnetic shielding and electromagnetic shielding.

The curing agent causes the solidification of the drill with the epoxy resin powder throughout the soft magnetic composite material to impart curing and molding functions of the soft magnetic composite material.

The curing agent contains 0.1 to 5% by mass based on the total mass of the soft magnetic composite material. The amount of curing agent and the epoxy resin powder are cured and crosslinked according to a certain mass ratio. When the curing agent is contained in an amount of less than 0.1% by mass, the epoxy resin is not completely cured and the strength of the soft magnetic composite material is also lowered. When the content of the curing agent exceeds 5% by mass, the epoxy resin is excessively cross-linked, and the soft magnetic composite material is brittle, making it impossible to use.

The mold release agent provides a mold release function by reducing the adhesive force between the soft magnetic composite material and the mold. The demoulding agent contains 1 to 5% by mass relative to the total mass of the soft magnetic composite material.

When used below 1% by mass, the mold release agent has poor releasability, and when it exceeds 5% by mass, the strength of the soft magnetic composite material becomes weak and brittle.

It is preferable to use manganese zinc ferrite (MnZn Ferrite) powder as the soft magnetic powder. Manganese zinc ferrite is not only physically stable, but also suitable for magnetic core materials due to its high magnetic permeability, high resistivity and good frequency characteristics. Manganese zinc ferrite has relatively low electromagnetic properties (eg, permeability) compared to the conventional nickel zinc ferrite, but low magnetic core loss (power loss) prevents ferrite from losing magnetism at a temperature higher than the environmental temperature of the product. In addition, manganese zinc ferrite can be injection molded by mixing with an epoxy resin. Conventional nickel zinc ferrite is a sintered material.

Injection molding facilitates the size adjustment of the soft magnetic composite material and simplifies the manufacturing process, thereby increasing productivity, and since it does not sinter, characteristics such as shrinkage can be minimized.

It is preferable that the particle diameter of the soft magnetic powder is d50≤50㎛. The particle diameter of the soft magnetic powder is important to ensure uniform mixing. In addition, since the particle diameter of the soft magnetic powder has a low surface electric resistance at d50≤50㎛, magnetic core loss is minimized. d50 means that the particle size of 50% is 50 µm or less. In detail, d50 means the particle diameter of the point at which the cumulative cover becomes 50% when the cumulative cover is obtained with the total volume of the measured powder as 100%.

The soft magnetic powder may have a shape close to an oval. The shape in which the soft magnetic powder approaches the elliptical shape is more effective for forming a magnetic network.

It is preferable that the epoxy resin powder has a particle size of d90 ≤ 10 μm, an epoxy value (equivalent/100 g) of 0.09 to 0.14, an epoxy equivalent (g/equivalent) of 714 to 1111, and a molecular weight of 2000.

The epoxy resin powder is a liquid curing adhesive. The epoxy value is the most important indicator for identifying the properties of the epoxy resin and determines the viscosity of the epoxy resin. Epoxy resins are classified into high-epoxy value resins when the epoxy value is greater than 0.4, mid-epoxy value resins when the epoxy value is 0.25 to 0.45, and low-epoxy value resins when the epoxy value is less than 0.25.

Epoxy resins with low epoxy values have low viscosity and excellent fluidity. Since the present invention uses a soft magnetic powder having a high magnetic powder filling amount, a low epoxy value resin having a low epoxy value is applied to ensure molding and processing performance of the soft magnetic powder. The epoxy value is 0.09 to 0.14, and the epoxy equivalent is obtained by converting the epoxy value, and the molecular weight of 2000 is also determined by the epoxy value.

If the epoxy value is less than 0.09, the molecular weight of the epoxy resin is so small that the viscosity can be minimized without cohesion, and it cannot be used as a binder for bonding the soft magnetic powder of the soft magnetic composite material. Above the epoxy value of 0.14, the epoxy resin cannot be filled with a high content of magnetic powder due to excessive increase in viscosity, so the epoxy resin has an epoxy value of 0.09 to 0.14.

The particle size of the epoxy resin powder makes it easy to dissolve the epoxy resin powder in an organic solvent such as acetone, and is easily mixed with the magnetic powder. Epoxy resin powder is easily dissolved in an organic solvent such as acetone in the range of the particle size of the epoxy resin powder d90≤10㎛, and is easily mixed with the magnetic powder. d90 means that 90% of the particle diameter is 10 µm or less. In detail, d90 means the particle diameter of the point at which the cumulative cover becomes 90% when the cumulative cover is obtained with the total volume of the measured powder as 100%.

It is preferable that the curing agent is an amine-based curing agent. Since the epoxy group has high reactivity with an amine, an amine-based curing agent is used as a curing agent for the epoxy resin. The amine-based curing agent has high thermosetting properties and curing reliability.

It is preferable that the release agent is zinc stearate. In addition, calcium stearate and magnesium stearate may be used as the mold release agent.

2 and 3 are cross-sectional views showing an example of an inductor manufactured using the soft magnetic composite material of the present invention.

2, the inductor 100 includes the outer core 170 with the inner core 130 assembled therein, and the inner core 130 includes the coil 150 connected to the terminal pin 110. It is injection molded. The inner core 130 is formed by injection molding a soft magnetic composite material slurry containing manganese zinc ferrite as a main component. The outer core 170 may be manufactured by compression molding a nickel zinc ferrite powder and then sintering it in a high temperature furnace.

As shown in FIG. 3, the coil 150 is wound on the injection base 120 of the soft magnetic composite material containing manganese zinc ferrite as a main component, the terminal pin 110 is connected, and then manganese is injected on the injection base 120. The inner core 130 may be manufactured by secondary injection of the injection material 125 of the soft magnetic composite material containing zinc ferrite as a main component.

The manufactured inner core 130 may be combined with the outer core 170 and then heat-sealed using a thermosetting resin 190. An inductor manufactured by injection molding with a soft magnetic composite material containing manganese zinc ferrite as a main component may be referred to as MPIC, and an inductor manufactured by sintering using a general ferrite manufacturing method may be referred to as MPI.

4, the method of manufacturing a soft magnetic composite material according to an embodiment of the present invention comprises dissolving the epoxy resin powder and a curing agent in an organic solvent to prepare an epoxy resin solution (S110), and removing the soft magnetic powder. Mixing with siblings to prepare a soft magnetic mixture (S120), mixing and stirring the epoxy resin solution and the soft magnetic mixture to make a slurry (S130), and injecting the slurry into a mold and heating and pressurizing to 150-180°C It comprises a step of manufacturing a molded body (S140).

In the step (S110) of preparing an epoxy resin solution, the epoxy resin is sufficiently dissolved. In the step of preparing the epoxy resin solution, the epoxy resin powder and the curing agent are dissolved in acetone, an appropriate amount of an organic solvent at a mass ratio of 95:5, and the epoxy resin solution is prepared by stirring vigorously until the epoxy resin powder is completely dissolved. do. The curing agent is an amine-based curing agent. Acetone may be used as the organic solvent. The prepared epoxy resin solution is an epoxy resin solution.

In the step (S120) of preparing a soft magnetic mixture, the soft magnetic powder is uniformly mixed with the demoulding agent. In the step of preparing the soft magnetic mixture, manganese zinc ferrite powder is mixed with a demoulding agent to form a soft magnetic mixture. The soft magnetic mixture is a manganese zinc ferrite powder material. The release agent uses zinc stearate.

In the step of making a slurry (S130), the soft magnetic powder is well mixed with the epoxy resin so that the surface of the soft magnetic powder is surrounded by the epoxy resin. In the step of making the slurry, the epoxy resin solution and the manganese zinc ferrite powder are slowly and uniformly stirred according to a certain mass ratio to make an epoxy manganese zinc ferrite slurry.

After the step of making the slurry, before the step of injecting the slurry into the mold, the step of removing the solvent by vacuum drying the slurry at a temperature of 40 to 60° C. for 2 to 4 hours is further performed. The step of removing the solvent is for facilitating injection by partially removing the solvent so that the slurry still has a constant flowability. The solvent is acetone.

The step of preparing the molded body (S140) is a final curing step, before the step of injecting the slurry into the mold to reduce the excessive solvent content, the solvent is discharged at a low temperature. The solvent affects the curing rate and the mold evacuation, so if not discharged, it causes defects such as bubbles in the molded body.

In the step of manufacturing the molded body (S140), the slurry is injected into the mold, and the mold is heated to 150 to 180°C, and then cured by pressing, evacuating, and maintaining pressure. Next, by cooling and demolding, a soft magnetic composite material molded body (hereinafter referred to as a'molded body') is obtained. The shaped body may be the inner core of the inductor. The inner core can be referred to as an inductor shell.

In the process of manufacturing the soft magnetic composite material, the epoxy resin must be cured by causing a reaction with a curing agent at a constant pressure and temperature, otherwise the epoxy resin is not cured normally. The curing speed of the epoxy resin is related to the capacity, time and temperature. When the content of the epoxy resin is high, a high temperature is required, and when pressurized at a temperature of 150 to 180°C, the curing time can be reduced to increase productivity. 150 to 180°C is the temperature at which the mold is heated. It is preferable that the pressing time of the slurry in the mold is 120 to 600 seconds. After pressurization, the exhaust performs vacuum exhaust. The vacuum exhaust is intended to prevent air bubbles from forming in the molded body. If not evacuated, air bubbles may form in the molded body.

Hereinafter, the present invention will be described in more detail through Examples and Comparative Examples. However, the examples are intended to illustrate the present invention, and the scope of the present invention is not limited thereto.

Table 1 shows the components and conditions of the soft magnetic composite material.

[Unit: mass% (g)] Ingredient/condition Soft magnetic powder Epoxy resin
powder Hardener Mold release Soft magnetic powder particle size Epoxy resin powder particle size Epoxy equivalent Vacuum drying Injection temperature Example 1 96.0
(3551) 2.6
(95) 0.1
(5) 1.3
(49) d50≤50㎛ d90≤10㎛ 0.1 50℃,
3 hours 150~180℃ Example 2 94.1
(1881) 4.8
(95) 0.3
(5) 1.0
(19) d50≤50㎛ d90≤10㎛ 0.1 50℃,
3 hours 150~180℃ Example 3 89
(891) 10
(95) One
(5) One
(9) d50≤50㎛ d90≤10㎛ 0.1 50℃,
3 hours 150~180℃ Comparative Example 1 80.2
(430) 17.7
(95) 0.9
(5) 1.1
(6) d50≤50㎛ d90≤10㎛ 0.1 50℃,
3 hours 150~180℃ Comparative Example 2 97.0
(4850) 1.9
(95) 0.1
(5) 1.0
(50) d50≤50㎛ d90≤10㎛ 0.1 50℃,
3 hours 150~180℃ Comparative Example 3 96.9
(3460) 1.8
(65) 0.1
(5) 1.1
(40) d50≤50㎛ d90≤10㎛ 0.1 50℃,
3 hours 150~180℃ Comparative Example 4 91.3
(3260) 2.5
(90) 5.1
(182) 1.1
(40) d50≤50㎛ d90≤10㎛ 0.1 50℃,
3 hours 150~180℃ Comparative Example 5 87.3
(3118) 2.5
(90) 0.06
(2) 5.1
(182) d50≤50㎛ d90≤10㎛ 0.1 50℃,
3 hours 150~180℃ Comparative Example 6 96.0
(3551) 2.6
(95) 0.1
(5) 1.3
(49) d50≤50㎛ d90>10㎛ 0.09 50℃,
3 hours 150~180℃ Comparative Example 7 96.0
(3551) 2.6
(95) 0.1
(5) 1.3
(49) d50>50㎛ d90≤10㎛ 0.14 50℃,
3 hours 150~180℃ Comparative Example 8 96.0
(3551) 2.6
(95) 0.1
(5) 1.3
(49) d50≤50㎛ d90≤10㎛ 0.08 50℃,
3 hours 150~180℃ Comparative Example 9 96.0
(3551) 2.6
(95) 0.1
(5) 1.3
(49) d50≤50㎛ d90≤10㎛ 0.15 50℃,
3 hours 150~180℃

Table 2 shows the properties of the soft magnetic composite material prepared under the components and conditions of Table 1.

characteristic Initial magnetic conductivity (μi) Saturation magnetic strength (Bs) mT Inductor loss (L) nH Example 1 500 1100 246 Example 2 270 650 163 Example 3 150 350 102 Comparative Example 1 60 450 95 Comparative Example 2 395 890 208 Comparative Example 3 389 860 202 Comparative Example 4 220 515 140 Comparative Example 5 142 337 98 Comparative Example 6 460 900 230 Comparative Example 7 410 780 205 Comparative Example 8 389 650 194 Comparative Example 9 330 510 180

[Example 1]

Take 95 g of epoxy resin powder and 5 g of an amine-based curing agent, dissolve in an appropriate amount of acetone, stir until completely dissolved, and then add a mixture of 3600 g of manganese zinc ferrite and zinc stearate, and mix uniformly. Next, it was vacuum dried under a temperature of 50° C. for 3 hours to obtain a slurry. Here, the capacity of zinc stearate is 49 g.

The obtained slurry was injected into the inner core mold and the outer core mold, respectively, and the molds were heated to 150 to 180° C., pressurized, exhausted, maintained, and cured, and cooled and demolded to obtain outer core and inner core.

Here, the outer core has an outer diameter of 40 mm, an inner diameter of 10 mm, and a height of 8 mm. The inner core has an outer diameter of 10 mm and a height of 5 mm. The number of coil turns is 10 turns.

The initial magnetic conductivity of Example 1 obtained by measuring according to the test standard of the inductor is μi=500, the saturation magnetic strength is Bs=1100 mT, and the inductor loss is L=246 nH.

[Example 2]

Take 95 g of epoxy resin powder and 5 g of amine-based curing agent, dissolve in an appropriate amount of acetone, stir until completely dissolved, add 1900 g of a mixture of manganese zinc ferrite and zinc stearate, and mix uniformly. Next, it was vacuum dried under a temperature of 50° C. for 3 hours to obtain a slurry. Here, the capacity of zinc stearate is 19 g.

The obtained slurry was injected into the inner core mold and the outer core mold, respectively, and the molds were heated to 150 to 180° C., pressurized, exhausted, maintained, and cured, and cooled and demolded to obtain outer core and inner core.

Here, the outer core has an outer diameter of 40 mm, an inner diameter of 10 mm, and a height of 8 mm. The inner core has an outer diameter of 10 mm and a height of 5 mm. The number of coil turns is 10 turns.

The initial magnetic conductivity of Example 2 obtained by measuring according to the test standard of the inductor is µi=270, the saturation magnetic strength is Bs=650mT, and the inductor loss is L=163nH.

[Example 3]

Take 95 g of epoxy resin powder and 5 g of amine-based curing agent, dissolve in an appropriate amount of acetone, stir until completely dissolved, add 900 g of manganese zinc ferrite and zinc stearate, and mix uniformly. Next, it was vacuum dried under a temperature of 50° C. for 3 hours to obtain a slurry. Here, the capacity of zinc stearate is 9 g.

The obtained slurry was injected into the inner core mold and the outer core mold, respectively, and the molds were heated to 150 to 180° C., pressurized, evacuated, maintained, warmed and cured, and cooled and demolded to obtain outer core and inner core.

Here, the outer core has an outer diameter of 40 mm, an inner diameter of 10 mm, and a height of 8 mm. The inner core has an outer diameter of 10 mm and a height of 5 mm. The number of coil turns is 10 turns.

The initial magnetic conductivity of Example 3 obtained by measuring according to the test standard of the inductor is µi=150, the saturation magnetic strength is Bs=350mT, and the inductor loss is L=102nH.

According to the experimental results, Examples 1 to 3 satisfy the characteristic criteria required by the present invention with an initial magnetic conductivity of 150 or more, a saturation magnetic strength of 350 mT or more, and an inductor loss of 102 nH or more.

[Comparative Example 1]

Take 95 g of epoxy resin powder and 5 g of an amine-based curing agent, dissolve in an appropriate amount of acetone, stir until completely dissolved, add 436 g of a mixture of manganese zinc ferrite and zinc stearate, and mix uniformly. Next, it was vacuum dried under a temperature of 50° C. for 3 hours to obtain a slurry. Here, the capacity of zinc stearate is 6 g.

The obtained slurry was injected into the inner core mold and the outer core mold, respectively, and the molds were heated to 150 to 180° C., pressurized, evacuated, maintained, warmed and cured, and cooled and demolded to obtain outer core and inner core.

The initial magnetic conductivity of Comparative Example 1 obtained by measuring according to the test standard of the inductor is μi=60, the saturation magnetic strength is Bs=450mT, and the inductor loss is L=95nH.

In Comparative Example 1, the content of the epoxy resin powder exceeded 10% by mass, and the content of the relatively soft magnetic powder was low, so that the magnetic conductivity was low, and as a result, it was difficult to serve as an electromagnetic wave shield.

[Comparative Example 2]

Comparative Example 2 has a soft magnetic powder content of 97.0 mass%, which is higher than the reference content of 80-96 mass%. In Comparative Example 2, the soft magnetic powder content was high, so the fluidity was reduced and molding into an inductor was difficult.

[Comparative Example 3]

In Comparative Example 3, the content of the soft magnetic powder was 96.9% by mass, which exceeded the reference content of 80-96% by mass, and the content of the epoxy resin powder was 1.8% by mass, which was less than the reference content of 2-10% by mass. In Comparative Example 3, molding was difficult because the content of the soft magnetic powder was high and the content of the relative epoxy resin powder was low.

[Comparative Example 4]

In Comparative Example 4, the content of the curing agent is 5.1% by mass, and does not satisfy the reference content of 0.1 to 5% by mass. In Comparative Example 4, the content of the curing agent was high, resulting in excessive curing, and a problem occurred after molding.

[Comparative Example 5]

In Comparative Example 5, the content of the curing agent was 0.06% by mass and did not satisfy the reference content of 0.1 to 5% by mass. Comparative Example 5 had a low strength because the content of the curing agent was low, and a problem occurred after molding.

[Comparative Example 6]

Comparative Example 6 had an epoxy resin powder particle size of d90>10 μm. In Comparative Example 6, since the particle size of the epoxy resin powder did not satisfy the condition of d90≤10㎛, there was a problem in that the dispersion was uneven and the adhesive strength was poor.

[Comparative Example 7]

Comparative Example 7 has a soft magnetic powder particle size of d50>50㎛. Comparative Example 7 had a magnetic core loss problem because the soft magnetic powder particle size did not satisfy the condition of d50≤50㎛.

[Comparative Example 8]

Comparative Example 8 has an epoxy equivalent of 0.08, which is less than the reference value of 0.09 to 0.14. In Comparative Example 8, since the epoxy equivalent was less than 0.09, the viscosity was low, so that it was not bonded to the molded body.

[Comparative Example 9]

Comparative Example 9 has an epoxy equivalent of 0.15, which exceeds the reference value of 0.09 to 0.14. In Comparative Example 9, since the epoxy equivalent was high in excess of 0.14, the epoxy resin could not be filled with a high content of magnetic powder due to excessive increase in viscosity, and it was difficult to secure magnetic conductivity.

From the above experimental results, it can be seen that the soft magnetic composite material according to the embodiment of the present invention satisfies the characteristic criteria required by the present invention with an initial magnetic conductivity of 150 or more, a saturation magnetic strength of 350 mT or more, and an inductor loss of 102 nH or more. In addition, it can be seen that since the strain is low compared to the plastic material, precise dimensional management is possible, and since it is a bonding structure, not a crystalline structure, it is strong against physical shock or thermal shock.

5 is a photograph showing various examples of shapes of an inductor manufactured using the soft magnetic composite material of the present invention.

As shown in FIG. 5, the soft magnetic composite material of the present invention can be injection molded, so when applied to inductor manufacturing, a fully enclosed magnetic structure is possible and can be manufactured in various shapes. This ensures quality uniformity and reliability of the inductor.

Moreover, injection molding has a lower deformation rate than sintering, allowing precise dimensional management.

For example, when the inductor is manufactured by a conventional sintering method, shrinkage or subtle warpage occurs by firing at high temperature (800 to 1300°C), and thus, a defect generation rate in which the inner core is not assembled to the outer core is high.

Since the above-described, soft magnetic composite material containing manganese zinc ferrite as a main component is an injection-molded bonding structure, it is very resistant to damage and cracks compared to the conventional nickel zinc ferrite, which is a crystal structure by sintering, and is very resistant to damage due to temperature changes, so that it is thermally shocked. Reliability is also greatly improved.

In addition, since the present invention can be manufactured by injection molding, as shown in FIG. 5, 2in1 and 3in1 of 16mm or more can be implemented, and various forms such as additional implementation according to customer demand are possible.

In addition, since the present invention is manufactured by injection molding, it is possible that the coil is not exposed to the outside, and thus, internal noise generated in the inductor can be fundamentally reduced, such as reduced operating noise and reduced vibration noise.

In addition, the present invention simplifies the manufacturing process of the core, so that it is possible to reduce the cost compared to the existing fired core and to stabilize the manufacturing quality.

FIG. 6 is a view for explaining the driving of FIG. 5C.

6, the inductor shows an example of a 3in1 inductor, and the inductor sets the magnetic flux generated by each coil as an independent passage by inducing the magnetic flux generated by the current through the magnetic core through the magnetic core. It is driven in an exercise manner. The magnetic flux has an N-S polarity, and the magnetic flux generated in N flows densely to the nearest S polarity, and it is possible to define the location of the magnetic flux density through the pore design of the magnetic core.

Although the above-described soft magnetic composite material is described as being applied to the inner core of the inductor as an example, it can be applied to various electronic devices.

The present invention has been described with the best embodiments in the drawings and specifications. Here, although specific terms are used, they are used only for the purpose of explaining the present invention and are not used to limit the scope of the present invention described in the meaning limitation or the claims. Therefore, the present invention will be understood by those skilled in the art that various modifications and other equivalent embodiments are possible. Therefore, the true technical scope of the present invention should be defined by the technical spirit of the appended claims.

10: inductor (inductor element) 11: terminal pin
13: inner core 15: coil
17: outer core 19: thermosetting resin
100: inductor 110: terminal pin
130: inner core (injection base) 150: coil
170: outer core 190: thermosetting resin

Claims (8)

delete delete delete delete delete delete Preparing an epoxy resin solution by dissolving an epoxy resin powder and a curing agent in an organic solvent;
Preparing a soft magnetic mixture by mixing the soft magnetic powder with a demoulding agent;
Mixing the epoxy resin solution and the soft magnetic mixture and stirring to make a slurry; And
Injecting the slurry into a mold and heating and pressing it to 150 to 180° C. to produce a molded body;
It includes,
After the step of making the slurry, before the step of injecting the slurry into the mold,
Method for producing a soft magnetic composite material further comprising the step of removing the solvent by vacuum drying the slurry at a temperature of 40 to 60°C for 2 to 4 hours. delete

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