KR20170137968A - Manufacturing method of power inductor - Google Patents

Abstract

Disclosed is a power inductor manufacturing method which has excellent magnetic properties, has a simple manufacturing process, and reduces manufacturing costs. The manufacturing method of the present invention includes: a step of manufacturing a mixture by dispersing and mixing third metal powder, which is at least one selected from a magnetic body and a soft magnetic body, with resin solution; a step of producing slurry for core molding by adding and mixing fourth metal powder having particles of the same size as one of the third metal powder while being selected as at least one from a magnetic body and a soft magnetic body in the mixture and producing a plurality of sheets from the slurry for core molding; a step of forming a stacked body of the plurality of sheets, forming a stacked bar by heating, compressing, and hardening the stacked body, and then manufacturing a core by processing the stacked bar; a step of manufacturing slurry for injection molding by dispersing and mixing fifth metal powder selected as at least one between a magnetic body and a soft magnetic body in resin solution; and a step of forming a main body by winding a coil on the core, inserting the wound core into a predetermined container, and hardening the slurry for injection molding into an intended shape by heating after injecting the slurry into the container to surround the core.

Description

TECHNICAL FIELD [0001] The present invention relates to a manufacturing method of a power inductor,

The present invention relates to a manufacturing method of a power inductor, and more particularly, to a manufacturing method of a power inductor, which is excellent in magnetic characteristics and at the same time simplifies a manufacturing process and reduces manufacturing costs.

Generally, a power inductor is manufactured by mixing a metal powder coated with an insulating layer with an epoxy resin and inserting a coil into the coil in various ways.

The manufacturing process is partially different depending on the manufacturer. However, the metal powder is selected as a metal magnetic material and used as a composite material dispersed in an epoxy resin. Generally, a power inductor is configured such that a coil is formed inside a body containing the composite material and connected to input and output electrodes respectively formed on the opposite outer surfaces of the body.

Particularly, a large-capacity power inductor used in an automobile is mainly manufactured by a molding process. The power inductor according to the molding process is manufactured by a method in which a coil is disposed inside and a slurry in which a magnetic metal powder coated with an insulating layer as a whole and an epoxy resin are mixed is injected. As a related art example, Japanese Patent Application Laid-Open No. 11-126724 (published on November 11, 1999) "Ceramic Inductor", a coil for winding at a predetermined pitch is prepared, ceramic powder slurry is injected around the coil, Thereby manufacturing an inductor.

However, since the above method must ensure flowability for injection molding of the slurry, there is a limit to increase the content of the metal solid content. This means that the filling rate of the metal powder can not be efficiently improved and there is a limit to the improvement of the magnetic characteristics, and the produced power inductor can not have high efficiency inductance characteristics.

Accordingly, it is an object of the present invention to provide a method of manufacturing a power inductor, which is excellent in magnetic characteristics of a power inductor to be manufactured, and at the same time, can be greatly simplified in manufacturing process and manufacturing cost can be reduced.

According to an aspect of the present invention, there is provided a method of manufacturing a power inductor, comprising dispersing and mixing a first metal powder selected from at least one of a magnetic material and a soft magnetic material into a resin solution to prepare a slurry for core molding, Producing a plurality of sheets from the forming slurry; Forming a laminate of the plurality of sheets, curing the laminate by pressing and pressing while heating the laminate to form a laminate bar, and then processing the laminate bar to manufacture a core; Dispersing and mixing a second metal powder selected from at least one of a magnetic material and a soft magnetic material into a resin solution to prepare a slurry for injection molding; A step of winding a coil around the core to enter a predetermined container, injecting the slurry for injection molding into the container to surround the core, and then curing the slurry into an intended shape while heating to form a body have.

In this case, the first metal powder and the second metal powder may be Fe powder, Fe-Si powder, Fe-Si-Al powder, CIP (Carbonyl Iron Powder) Fe-Si-Cr-based powder and Fe-Si-B-Cr-based powder.

Also, the first metal powder may be selected to have a smaller particle size than the second metal powder.

According to another aspect of the present invention, there is provided a method of manufacturing a power inductor, comprising: dispersing and mixing a third metal powder selected from at least one of a magnetic material and a soft magnetic material into a resin solution to prepare a mixture; A fourth metal powder selected from at least one of a magnetic material and a soft magnetic material and having a particle size different from that of the third metal powder is added to and mixed with the mixture to prepare a slurry for core molding, Producing a sheet; Forming a laminate of the plurality of sheets, curing the laminate by pressing and pressing while heating the laminate to form a laminate bar, and then processing the laminate bar to manufacture a core; Dispersing and mixing a fifth metal powder selected from at least one of a magnetic material and a soft magnetic material into a resin solution to prepare an injection molding slurry; A step of winding a coil around the core to enter a predetermined container, injecting the slurry for injection molding into the container to surround the core, and then curing the slurry into an intended shape while heating to form a body have.

At this time, the third metal powder may be selected to have a smaller particle size than the fourth metal powder. The third metal powder and the fourth metal powder may be selected to have a smaller particle size than the fifth metal powder.

The third metal powder, the fourth metal powder and the fifth metal powder may be Fe powder, Fe-Si powder, Fe-Si-Al powder (Sendust), CIP (Carbonyl Iron Powder) Ni-based powder, Fe-Si-Cr-based powder and Fe-Si-B-Cr-based powder.

In addition, the resin solution may be formed of a polyacrylate resin, an epoxy resin, a phenolic resin, a polyamide resin, a polyimide resin, an unsaturated polyester resin, Unsaturated polyesters resins, polyphenylene ether resins (PPE), polyphenylenesulfides resins, cyanate ester resins and benzocyclobutene (BCB) resins. Of the thermosetting resin group.

Further, at least one of the core molding slurry and the injection molding slurry may contain a dispersant, and the dispersant may be a nonionic surfactant, a cationic surfactant, an anionic surfactant, an alkylammonium salt-based copolymer, One or more selected from the group consisting of polyols, polyols, polyols, polyols, polyols, polyols, coalescent, ester nonionic, fish oil and polyacrylate.

In addition, the content of the metal solid content in the core molding slurry may be controlled within the range of 55 to 70 vol% based on the total amount of the core molding slurry.

The content of the third metal powder may be adjusted to 30 to 80 vol% based on the total amount of the metal solid content contained in the core molding slurry.

Further, the slurry for injection molding may be adjusted to have a lower viscosity than the slurry for core molding.

In addition, the content of the metal solid content in the slurry for injection molding may be controlled within the range of 55 to 65 vol% based on the total amount of the slurry for injection molding.

In addition, the production of a plurality of sheets from the core molding slurry can be performed by a process of tape casting, screen printing, wet coating or inkjet printing.

In addition, the injection molding slurry may be defoamed prior to injection into the vessel.

The manufacturing method of the present invention may further include the step of forming terminal electrodes for input and output on at least one surface of the body and electrically connecting both ends of the coil to the terminal electrodes have.

In the power inductor manufactured by the manufacturing method of the present invention, the core has a high filling ratio of the metal solid content and is excellent in magnetic characteristics. At the same time, the metal powder slurry of low viscosity is simply injected and hardened around the core, The manufacturing cost can be reduced.

1 is a schematic structural view of a general power inductor manufactured by the present invention.
2A to 2C are schematic diagrams for explaining a method of manufacturing a power inductor according to the present invention, in which FIG. 2A shows a core 12 in which a coil 14 is wound, FIG. 2B shows a state in which the coil 14 in FIG. The core 12 is housed in the inductor case, and Fig. 2C shows that the slurry for injection molding is injected into the inductor case.
3 is a flowchart illustrating a method of manufacturing a power inductor according to the present invention.
4a to 4c show electron microscopic photographs of metal powders usable in the present invention. Fig. 4a shows the Fe-Si-Al powder, Fig. 4b shows the Fe-Si powder, It is a photograph.
5 is a cross-sectional view of a cross-section of a thick sheet formed by tape casting of a slurry of Fe-Si-based powder and CIP powder composition mixed to form core 12 in step iii) It is an electron microscope photograph.
Fig. 6 is a graph showing the viscosity change according to the metal solid content in the prepared injection molding slurry in the step (v) of the embodiment of the present invention for the production of slurry for injection molding.
FIG. 7 is electron micrographs of the inductor main body 10 manufactured in the step vi) of the embodiment of the present invention.

1 is a schematic structural view of a general power inductor manufactured by the present invention.

1, the power inductor 10 generally comprises a core 12 disposed inside the main body 10 and a coil 14 for winding the core 12 at a predetermined pitch. The main body 10 is enclosed by a case 15 such as a rectangular case formed by coating the outside with an epoxy resin or the like and each end portion 14a and 14b of the coil 14 is opposed to the case 15 And is electrically connected to the input terminal electrode 17a and the output terminal electrode 17b respectively formed on the front surface or the partial surface of the two outer surfaces.

According to the present invention, the core 12 is formed of a magnetic material or a soft magnetic metal powder. Preferably, the metal powder may be coated with an insulator to ensure the designed electromagnetic characteristics, and may be, for example, Fe-Si powder composition, as will be described below.

Around the core 12, a slurry in which a metal powder is dispersed is injected into a resin solution in which a resin is dissolved in a solvent, and hardened. In particular, the slurry may be adjusted to a low viscosity to facilitate pouring. Since the viscosity of the slurry is relatively low, the metal solid content dispersed in the slurry is small, which may cause a limitation in the filling amount.

In order to compensate for this, in the present invention, the core 12 is formed by a thick film process and a plurality of laminated and processed thick film sheets. That is, the slurry surrounding the core 12 has a low fill factor and has a low metal solids content, but the core 12 has a high metal solids content by being laminated and formed as thick sheet sheets. Thus, the slurry injected around the core 12 has a relatively low filling rate, but instead has a low viscosity, thereby facilitating its injection molding, while maintaining a very high fill factor in the core 12, So that a high inductance value can be maintained. According to the present invention, the filling rate in the core 12 is preferably 65 to 77 vol%, more preferably 75 vol%, relative to the volume of the core 12.

2A to 2C are schematic views for explaining a method of manufacturing the power inductor according to the present invention. Hereinafter, a manufacturing method according to the present invention will be described with reference to these drawings.

Manufacture of cores

First, as shown in FIG. 2A, the core 12 is manufactured and the coil 14 is wound around the surface.

In the present invention, the core 12 may be manufactured by mixing a metal powder with a resin solution according to a conventional thick film process to prepare a slurry, forming a plurality of thick film sheets, and laminating and processing the same.

The slurry may be formed into a thick film sheet by tape casting. However, the present invention is not limited thereto, and the slurry may be formed into a known sheet including screen printing, wet coating or inkjet printing. All thick film processes can be used.

Then, the laminate of the plurality of thick-film sheets is cured at a predetermined curing temperature of the resin used, pressed and pressed to form a thick composite plate, and then processed into the shape of the desired core 12 to form the core 12. Here, the shape of the core 12 is illustrated as a general cylinder shape for convenience, but the present invention is not limited thereto. In one embodiment, the laminate may be made of a composite plate by forming a lamination bar while applying a predetermined curing temperature and pressure using a hot press.

The metal powder may be Fe powder, Fe-Si powder, Fe-Si-Al powder, CIP powder, Fe-Ni powder, Fe-Si-Cr powder, Fe-Si-B-Cr-based powder. In one embodiment, the metal powder of the core 12 may be a mixture of Fe-Si-based powder and CIP powder.

The resin may be a resin such as a polyacrylate resin, an epoxy resin, a phenolic resin, a polyamide resin, a polyimide resin, an unsaturated polyester resin, It is also possible to use unsaturated polyesters resin, polyphenylene ether resin (PPE), polyphenylenesulfides resin, cyanate ester resin and benzocyclobutene (BCB). But the present invention is not limited thereto and any other known thermosetting resin may be used.

The slurry prepared by dispersing the metal powder in the resin solution may include a dispersing agent for promoting the dispersion of the metal powder. The dispersing agent may be a nonionic surfactant, a cationic surfactant, an anionic surfactant, an alkylammonium salt- At least one member selected from the group consisting of alkylammonium salt copolymers, ester nonionic systems, fish oil and polyacrylates.

Injection molding  Manufacture and injection of slurry, manufacture of inductor

Meanwhile, as described above in the present invention, it is preferable that the slurry for injection molding injected around the core 12 is made of a slurry having a high concentration so as to ensure a large amount of metal solid content while facilitating injection with a low viscosity.

The slurry for injection molding may be prepared by dispersing and mixing the metal powder in a resin solution, and the components of the metal powder and resin contained in the slurry and the components of the dispersant that can be contained in the slurry are the same as those of the core 12 ), And the components of the metal powder, the resin and the dispersing agent listed in relation to the metal powder, the resin and the dispersing agent. The metal powder is preferably dispersed and mixed in a range of 55 to 65 vol% based on the total amount of the slurry.

Then, as shown in FIGS. 2B to 2C, the core 12 in which the coil 14 is wound is placed in the inductor case, the injection molding slurry is injected around the core 12, .

The inductor body thus formed has input terminal electrodes 17a and output terminal electrodes 17b formed on two opposing surfaces or on at least one surface of the front surface or a part of the surface thereof, The final inductor 10 can be manufactured by electrically connecting the ends 14a and 14b.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, it is to be understood that the present invention is not limited to the following examples, but the present invention is not limited thereto.

Example

As an embodiment of the present invention, the metal powder for manufacturing the core 12 may be a mixture of a Fe-Si-based powder and a CIP powder, and the inductor 10 of the present invention may be formed by mixing the Fe- And the like. 3 is a flowchart illustrating a method of manufacturing a power inductor according to the present invention.

i) CIP powder having a relatively small particle size (3 to 4 탆) as compared with the particle size (10 to 12 탆) of the Fe-Si-based powder is first dispersed in the epoxy resin solution And mix. For example, the mixing may be performed using a paste mixer at 300 rpm for about 1 hour.

ii) The slurry is prepared by adding an Fe-Si-based powder having relatively larger particles to a solution in which the CIP powder is dispersed and then mixing. At this time, the total amount of metal solid content is controlled to 55 to 75 vol% based on the total amount of the slurry, and the content of the CIP powder is adjusted to 30 to 80 vol% with respect to the total amount of the metal solid content. For example, the mixing may be performed using a paste mixer at 200 rpm for about 2 hours.

iii) Using the slurry, a plurality of composite sheets were prepared by tape casting at a temperature of 80 占 폚 in a thickness of 100 占 퐉 and laminated. Then, the laminate is compressed and pressed at a temperature of about 170 to 175 DEG C under a curing condition to form a thick composite plate, and the laminate is processed to manufacture a core 12 in a cylindrical shape. For example, the laminate is pressurized with a hot press at a temperature of about 175 DEG C and a pressure of about 1200 psi for about 3 minutes to form a laminate bar, and the composite plate is cut by a blade cutter, The core 12 can be manufactured.

iv) Thereafter, the coil 14 is wound around the main surface of the core 12 (see Fig. 2a).

v) Meanwhile, the sendust powder is dispersed and mixed in the range of 55 to 65 vol% based on the total amount of the slurry for injection molding produced in the epoxy resin solution to prepare slurry for injection molding. For example, after mixing and dispersing at 1200 rpm for 5 minutes, slurry defoaming can be performed for 30 minutes in order to stabilize slurry and remove bubbles, thereby preparing slurry for injection molding.

vi) Then, the core 12 in which the coil 14 is wound is housed in the inductor case, the injection molding slurry is injected around the core 12, and then molded by curing at about 170 캜 for about one hour Thereby manufacturing the inductor main body.

vii) Thereafter, a known metal paste is applied to the front surface or a part of the surface of one set of opposing surfaces of the main body to form input terminal electrodes 17a and 17b electrically connected to both ends 14a and 14b of the coil 14, The final inductor 10 can be manufactured by forming the terminal electrode 17b.

FIGS. 4A to 4C show electron micrographs of metal powders usable in the present invention, wherein FIG. 4A is a powder of Fe-Si-Al, FIG. 4B is Fe-Si powder, It is a photograph.

Referring to FIGS. 4A to 4C, these powders have different particle sizes, and the size of the sendust powder is about 90 μm, the Fe-Si powder is about 10-12 μm, and the CIP powder is about 3-4 μm.

Therefore, according to a preferred embodiment of the present invention, by mixing two or more metal powders having different particle sizes, it is possible to improve the filling rate and magnetic properties of the metal powder.

According to the present invention, as the slurry component of the core 12 having a high concentration and a high viscosity, it is preferable to use a Fe-Si-based powder and / or CIP having a relatively small particle size. On the other hand, As the component of the slurry for injection molding, it is preferable to use a heavy dust powder having a relatively large particle size to prepare the slurry having a low viscosity and a high content of metal solid content.

Fig. 5 is a cross-sectional view of the core sheet 12 produced by tape casting a slurry of Fe-Si-based powder and CIP powder composition mixed to form core 12 in step iii) Sectional micrograph.

As a result of quantitative filling density analysis with an image analyzer, the maximum packing density of about 75.48% was obtained when a thick sheet was formed under the condition of a solid content of 70 vol%.

6 is a graph showing the change in viscosity ("Viscosity") according to the content of the metal solid ("Solid loading") in the step v) of the embodiment of the present invention described above for the production of slurry for injection molding.

As shown in FIG. 6, the viscosity increases as the content of the metal solid content increases. In the range where the content of the metal solid is relatively low, the range of the viscosity is small, but in the range of 60 to 65 vol%, the viscosity is abruptly changed and the fluidity is decreased, which makes the slurry injection process difficult. The lower the metal solid content of the slurry is, the more easily the injection molding becomes. However, since the magnetic properties are reduced instead, it is preferable to find the range of the metal solid content which maximizes the effect by compromising the both sides. According to the present invention, the metal solid content of the slurry for injection molding is preferably in the range of 55 to 65 vol% based on the total amount.

FIG. 7 is electron micrographs of the inductor main body manufactured in the step vi) of the embodiment of the present invention, and each of the marked portions is enlarged and shown.

Core 12 "portion at the center and the" peripheries of the core 12 "which is the hardened and molded portion of the injected slurry at the left and right sides, respectively, based on the two boundary surfaces shown by the broken lines in FIG. 7 And at the bottom, an enlarged picture of each of these parts is shown. It also shows four portions of the "coil 14" wound around the center "core 12".

7, the "core 12" portion has a very high filling density of about 75.48% with respect to the portion of the wound coil 14, and the "portion around the core 12" has a relatively low filling density It is about 65 ~ 70% and it can be seen that they are uniformly distributed without pores.

As described above, according to the present invention, in the power inductor, the core 12 is made of a metal powder slurry of high viscosity, and a plurality of thick-sheet sheets are produced and laminated and processed so as to increase the filling ratio of the solid metal. A metal powder slurry having a low viscosity is injected and cured to form a metal solid material, the filling rate of the metal solid material is low, but the injection can be facilitated and the manufacturing of the inductor can be facilitated.

Thus, in the inductor manufactured according to the present invention, the core 12 has a high filling ratio of the metal solid content and is excellent in magnetic characteristics. Simultaneously, the metal powder slurry of low viscosity is simply injected around the core 12, The manufacturing process can be greatly simplified and the manufacturing cost can be reduced.

The various characteristics of the preferred embodiments of the present invention described above may vary somewhat within a conventional error range depending on the powder characteristics such as the average particle size, distribution and specific surface area of the composition powder, and the purity of the raw material, Is quite natural for those of ordinary skill in the art.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. , Additions and the like are to be regarded as belonging to the claims. For example, in the above-mentioned examples i) to ii), the CIP powder having a particle size relatively smaller than the particle size of the Fe-Si-based powder is first dispersed and mixed in the resin solution, The Fe-Si-based powder having a relatively large particle size is first dispersed and mixed in the resin solution by changing the order of the Fe-Si-based powder, and then the CIP powder having a relatively small particle size is mixed It is easy to replace it.

The present invention relates to an inductor, and more particularly, to an inductor, and more particularly,

Claims (17)

Dispersing and mixing a first metal powder selected from at least one of a magnetic material and a soft magnetic material into a resin solution to prepare a core molding slurry and manufacturing a plurality of sheets from the core molding slurry;
Forming a laminate of the plurality of sheets, curing the laminate by pressing and pressing while heating the laminate to form a laminate bar, and then processing the laminate bar to manufacture a core;
Dispersing and mixing a second metal powder selected from at least one of a magnetic material and a soft magnetic material into a resin solution to prepare a slurry for injection molding;
A step of winding a coil around the core and drawing it into a predetermined container, injecting the slurry for injection molding into the container so as to surround the core, and then curing the slurry into an intended shape while heating to form a body Wherein the method comprises the steps of: The method according to claim 1,
The first metal powder and the second metal powder may be Fe powder, Fe-Si powder, Fe-Si-Al powder (Sendust), Carbonyl Iron Powder (CIP) Si-Cr-based powder and Fe-Si-B-Cr-based powder. The method according to claim 1,
Wherein the first metal powder is smaller in particle size than the second metal powder. Dispersing and mixing a third metal powder selected from at least one of a magnetic material and a soft magnetic material into a resin solution to prepare a mixture;
A fourth metal powder selected from at least one of a magnetic material and a soft magnetic material and having a particle size different from that of the third metal powder is added to and mixed with the mixture to prepare a slurry for core molding, Producing a sheet;
Forming a laminate of the plurality of sheets, curing the laminate by pressing and pressing while heating the laminate to form a laminate bar, and then processing the laminate bar to manufacture a core;
Dispersing and mixing a fifth metal powder selected from at least one of a magnetic material and a soft magnetic material into a resin solution to prepare an injection molding slurry;
A step of winding a coil around the core and drawing it into a predetermined container, injecting the slurry for injection molding into the container so as to surround the core, and then curing the slurry into an intended shape while heating to form a body Wherein the method comprises the steps of: 5. The method of claim 4,
Wherein the third metal powder has a relatively small particle size as compared to the fourth metal powder. The method according to claim 4 or 5,
Wherein the third metal powder and the fourth metal powder are smaller in particle size than the fifth metal powder. The method according to claim 4 or 5,
The third metal powder, the fourth metal powder and the fifth metal powder may be Fe powder, Fe-Si powder, Fe-Si-Al powder (Sendust), Carbonyl Iron Powder (CIP) Based powder, Fe-Si-Cr-based powder, and Fe-Si-B-Cr-based powder. The method according to claim 1 or 4,
The resin solution may be at least one selected from the group consisting of a polyacrylates resin, an epoxy resin, a phenolic resin, a polyamide resin, a polyimide resin, an unsaturated polyester resin (unsaturated polyesters resin), polyphenylene ether resin (PPE), polyphenylenesulfides resin, cyanate ester resin and benzocyclobutene (BCB). Wherein the resin is a solution of at least one resin selected from the group of thermosetting resins. The method according to claim 1 or 4,
Wherein at least one of the core molding slurry and the injection molding slurry contains a dispersing agent. 10. The method of claim 9,
The dispersant may be at least one selected from the group consisting of a nonionic surfactant, a cationic surfactant, an anionic surfactant, an alkylammonium salt-based copolymer, an alkylol ammonium salt copolymer, an ester nonionic system, a fish oil and a polyacrylate Wherein the power inductor is made of a metal. The method according to claim 1 or 4,
Wherein the content of the metal solid content in the slurry for forming a core is controlled to be in the range of 55 to 70 vol% based on the total amount of the slurry for core shaping. 5. The method of claim 4,
Wherein the content of the third metal powder is adjusted to 30 to 80 vol% based on a total amount of solid metal contained in the slurry for forming a core. The method according to claim 1 or 4,
Wherein the slurry for injection molding has a viscosity lower than that of the core-forming slurry. The method according to claim 1 or 4,
Wherein the content of the metal solid content in the slurry for injection molding is controlled to be in the range of 55 to 65 vol% based on the total amount of the slurry for injection molding. The method according to claim 1 or 4,
Wherein the production of the plurality of sheets from the core molding slurry is performed by a process of tape casting, screen printing, wet coating or inkjet printing. The method according to claim 1 or 4,
Wherein the slurry for injection molding is defoamed before being injected into the vessel. The method according to claim 1 or 4,
Further comprising the step of forming each terminal electrode for input and output on at least one surface of the body and electrically connecting both ends of the coil to the respective terminal electrodes.

Images