KR20160136267A - Power inductor - Google Patents

Abstract

The present invention discloses a power inductor. The power inductor includes a body comprising a plurality of metal powders and a polymer; a substrate prepared in the body; a coil pattern prepared on at least one side of the substrate; and an outer electrode formed outside the body and connected to the coil pattern. The body further comprises a thermal conductivity filler for discharging the heat of the metal powder to the outside. In the thermal conductivity filler, the content of at least one region is different from that of another region. So, the degradation of inductance can be prevented.

Description

Power inductor {Power inductor}

The present invention relates to a power inductor, and more particularly, to a power inductor having an excellent inductance characteristic and improved thermal stability.

The power inductor is mainly provided in a power supply circuit such as a DC-DC converter in a portable device. Such a power inductor is being used in place of a conventional choke coil pattern (choke coil) in accordance with the increase in frequency and size of a power supply circuit. In addition, the power inductor is being developed in the direction of miniaturization, high current, low resistance and the like in accordance with the size reduction and the multifunctionalization of the portable device.

The power inductor can be manufactured in the form of a laminate in which a plurality of ceramic sheets made of a ferrite or a low dielectric constant dielectric material are stacked. At this time, a metal pattern is formed on the ceramic sheet in the form of a coil pattern. The coil patterns formed on the respective ceramic sheets are connected by conductive vias formed in the respective ceramic sheets, and are stacked in the vertical direction . The body constituting such a power inductor is conventionally manufactured by using a magnetic material composed of a quaternary material of nickel (Ni) - zinc (Zn) - copper (Cu) - iron (Fe).

However, since the magnetic material has a lower saturation magnetization value than the metal material, it may fail to realize the high current characteristics required by recent portable devices. Therefore, by manufacturing the body constituting the power inductor using metal powder, the saturation magnetization value can be relatively increased as compared with the case where the body is made of a magnetic body. However, when the body is made of metal, the loss of the eddy current and the hysteresis at the high frequency are increased and the loss of the material is increased. In order to reduce the loss of these materials, a structure in which the metal powder is insulated with a polymer is applied.

However, there is a problem that the inductance of the power inductor in which the body is manufactured using the metal powder and the polymer is lowered due to the temperature rise. That is, the temperature of the power inductor rises due to the heat generated by the portable device to which the power inductor is applied, and thus the metal powder forming the body of the power inductor is heated, resulting in a problem that the inductance is lowered.

Korean Patent Publication No. 2007-0032259

The present invention provides a power inductor capable of improving stability against temperature and thereby preventing inductance from deteriorating.

The present invention provides a power inductor capable of improving temperature stability by releasing heat in a body.

A power inductor according to one aspect of the present invention includes a body including a plurality of metal powders and a polymer; A base provided within the body; A coil pattern provided on at least one side of the substrate; And an external electrode formed on the outside of the body and connected to the coil pattern, wherein the body further includes a thermally conductive filler for discharging the heat of the metal powder to the outside, wherein the thermally conductive filler comprises at least one region Content is different from other areas.

The metal powder includes at least one material having at least two sizes.

The thermally conductive filler is made of a material different from the metal powder.

The polymer is contained in a smaller amount than the metal powder.

The thermally conductive filler is included in the same or different amount as the polymer.

The coil pattern is formed by a plating process, and is formed on one surface and the other surface of the substrate, respectively, and connected through conductive vias formed in the substrate.

At least a part of the external electrode is formed of the same material as the coil pattern.

At least a part of the external electrode is formed by plating.

A power inductor according to another aspect of the present invention includes a body; A base provided within the body; And a coil pattern provided on at least one side of the substrate, wherein the body includes at least three or more materials having different functions.

The body includes a first material having a predetermined permeability, a second material releasing heat of the body to the outside, and a third material insulating the first and second materials.

A power inductor according to embodiments of the present invention is fabricated using a metal powder, a polymer, and a thermally conductive filler. By including the thermally conductive filler, the heat of the body can be well discharged to the outside, thereby preventing a decrease in inductance due to the heating of the body.

In addition, it is also possible to prevent the lowering of the magnetic permeability of the power inductor by forming a base material provided inside the body and formed with a coil pattern from a metal magnetic body.

1 is a perspective view of a power inductor according to an embodiment of the present invention;
FIG. 2 is a cross-sectional view taken along line AA 'of FIG. 1; FIG.
3 to 5 are cross-sectional views illustrating a method of manufacturing a power inductor according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of other various forms of implementation, and that these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know completely.

FIG. 1 is a perspective view of a power inductor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line A-A 'of FIG.

1 and 2, a power inductor according to an embodiment of the present invention includes a body 100 including a thermally conductive filler 130, a base material 200 provided inside the body 100, Coil patterns 310 and 320 formed on at least one side of the body 100 and external electrodes 410 and 420 provided outside the body 100. [

The body 100 may be, for example, in a hexahedral shape. However, the body 100 may have the shape of a polyhedron other than a hexahedron. The body 100 may include a metal powder 110, a polymer 120, and a thermally conductive filler 130. The metal powder 110 may have an average particle diameter of 1 占 퐉 to 50 占 퐉. The metal powder 110 may be a single particle of the same size or two or more kinds of particles, or a single particle having a plurality of sizes or two or more kinds of particles may be used. For example, a first metal particle having an average size of 30 mu m and a second metal particle having an average size of 3 mu m can be mixed and used. When two or more metal powders 110 having different sizes are used, the filling rate of the body 100 can be increased and the capacity can be maximized. For example, when a metal powder of 30 mu m is used, voids may be generated between metal powder of 30 mu m, and the filling rate is accordingly lowered. However, it is possible to increase the filling rate by mixing metal powders of 3 mu m smaller in size than metal powders of 30 mu m in size. The metal powder 110 may be a metal material including iron (Fe), for example, Fe-Ni, Fe-Ni-Si, Silicon (Fe-Al-Si) and iron-aluminum-chromium (Fe-Al-Cr). That is, the metal powder 110 may be formed of a metal alloy containing iron or a magnetic texture or having a magnetic property, and may have a predetermined permeability. In addition, the metal powder 110 may be coated with a material whose surface has a magnetic permeability different from that of the metal powder 110. For example, the magnetic body may be formed of a metal oxide magnetic body, and may be formed from a group consisting of a nickel oxide magnetic body, a zinc oxide magnetic body, a copper oxide magnetic body, a manganese oxide magnetic body, a cobalt oxide magnetic body, a barium oxide magnetic body and a nickel- At least one oxide magnetic material selected may be used. That is, the magnetic material coated on the surface of the metal powder 110 may be formed of a metal oxide containing iron, and preferably has a higher permeability than the metal powder 110. The polymer 120 may be mixed with the metal powder 110 to insulate the metal powder 110. That is, the metal powder 110 may have a problem of high loss of eddy current and hysteresis at high frequencies, thereby causing a loss of material. In order to reduce the loss of the material, 120). The polymer 120 may include, but is not limited to, one or more polymers selected from the group consisting of epoxy, polyimide, and Liquid Crystalline Polymer (LCP). In addition, the polymer 120 may be made of a thermosetting resin to provide insulation between the metal powders 110. Examples of the thermosetting resin include Novolac Epoxy Resin, Phenoxy Type Epoxy Resin, BPA Type Epoxy Resin, BPF Type Epoxy Resin, , Hydrogenated BPA Epoxy Resin, Dimer Acid Modified Epoxy Resin, Urethane Modified Epoxy Resin, Rubber Modified Epoxy Resin, (DCPD Type Epoxy Resin), and the like. Here, the polymer 120 may be contained in an amount of 2.0 wt% to 5.0 wt% with respect to 100 wt% of the metal powder. However, when the content of the polymer 120 is increased, the volume fraction of the metal powder 110 is lowered, so that the effect of increasing the saturation magnetization value is not realized properly, and the magnetic characteristics of the body 100, If the content of the polymer 120 decreases, strong acid or strong base solution used in the manufacturing process of the inductor may permeate into the inside of the inductor, thereby reducing inductance characteristics. Accordingly, the polymer 120 may be included within a range that does not lower the saturation magnetization value and the inductance of the metal powder 110. In addition, the thermally conductive filler 130 is included to solve the problem that the body 100 is heated by external heat. That is, the metal powder 110 of the body 100 can be heated by external heat, and the heat of the metal powder 110 can be released to the outside by including the thermally conductive filler 130. The thermally conductive filler 130 may include at least one selected from the group consisting of MgO, AlN, and carbon-based materials, but is not limited thereto. Here, the carbon-based material includes carbon and may have various shapes such as graphite, carbon black, graphene, graphite, and the like. In addition, the thermally conductive filler 130 may be contained in an amount of 0.5 wt% to 3 wt% with respect to 100 wt% of the metal powder 110. When the content of the thermally conductive filler (130) is less than the above range, heat dissipation effect can not be obtained, and when it exceeds the above range, the permeability of the metal powder (110) is lowered. The thermally conductive filler 130 may have a size of, for example, 0.5 to 100 占 퐉. That is, the thermally conductive filler 130 may have a size larger or smaller than the metal powder 110. Meanwhile, the body 100 may be manufactured by laminating a plurality of sheets made of a material including the metal powder 110, the polymer 120, and the thermally conductive filler 130. Here, when the body 100 is manufactured by laminating a plurality of sheets, the content of the thermally conductive filler 130 of each sheet may be different. For example, as the distance from the substrate 200 to the upper side and the lower side increases, the content of the thermally conductive filler 130 in the sheet may increase. The body 100 may be formed by printing a paste made of a material including the metal powder 110, the polymer 120 and the thermally conductive filler 130 to a predetermined thickness or by pressing the paste into a mold Various methods may be applied as needed. At this time, the number of sheets to be laminated to form the body 100 or the thickness of the paste to be printed at a predetermined thickness may be determined to be an appropriate number or thickness in consideration of electrical characteristics such as inductance required in the power inductor.

The substrate 200 may be provided inside the body 100. At least one or more substrates 200 may be provided. For example, the base material 200 may be provided along the major axis direction of the body 100 inside the body 100. For example, the two substrates 200 may be spaced apart from each other by a predetermined distance in a direction orthogonal to the direction in which the external electrodes 400 are formed, for example, a vertical direction . The substrate 200 may be made of, for example, copper clad lamination (CCL) or metal magnetic material. At this time, the base material 200 is made of a metal magnetic material, thereby increasing the permeability and facilitating the implementation of the capacity. That is, CCL is manufactured by bonding a copper foil to a glass reinforcing fiber. Since CCL does not have a magnetic permeability, the permeability of a power inductor is lowered. However, when the metal magnetic material is used as the base material 200, the permeability of the power inductor is not lowered because the metal magnetic material has the magnetic permeability. The substrate 200 using such a metal magnetic material may be formed of a metal containing iron such as iron-nickel (Fe-Ni), iron-nickel-silicon (Fe-Ni-Si) -Si) and iron-aluminum-chrome (Fe-Al-Cr). That is, the base material 200 can be manufactured by preparing an alloy of at least one metal including iron and having a predetermined thickness, and bonding the copper foil to at least one surface of the metal plate. In addition, at least one conductive via (not shown) may be formed in a predetermined region of the substrate 200, and the coil patterns 310 and 320, which are formed on the upper and lower sides of the substrate 200 by conductive vias, . The conductive vias may be formed by forming a via (not shown) penetrating the substrate 200 along the thickness direction, and then filling the via with a conductive paste.

The coil patterns 310 and 320 may be formed on at least one surface, preferably both surfaces, of the substrate 200. The coil patterns 310 and 320 may be formed in a spiral shape from a predetermined region of the base material 200, for example, from a central portion of the base material 200, and two coil patterns 310 and 320 formed on the base material 200 may be connected So that a single coil can be formed. Here, the upper side coil pattern 310 and the lower side coil pattern 320 may have the same shape. The coil patterns 310 and 320 may be formed to overlap with each other or may be formed to overlap the region where the coil pattern 310 is not formed. The coil patterns 310 and 320 may be electrically connected to each other by conductive vias formed in the substrate 200. The coil patterns 310 and 320 can be formed by, for example, thick film printing, coating, vapor deposition, plating, and sputtering. In addition, the coil patterns 310 and 320 and the conductive vias may be formed of a material including at least one of silver (Ag), copper (Cu), and copper alloy, but is not limited thereto. On the other hand, when the coil patterns 310 and 320 are formed by a plating process, for example, a metal layer, for example, a copper layer may be formed on the base material 200 by a plating process, and patterned by a lithography process. That is, the coil patterns 310 and 320 can be formed by forming a copper layer by a plating process using a copper foil formed on the surface of the base material 200 as a seed layer, and patterning the copper foil. Of course, after forming a photoresist pattern having a predetermined shape on the substrate 200, plating is performed to grow a metal layer from the exposed surface of the substrate 200, and then the photoresist is removed to form coil patterns 310 and 320 having a predetermined shape . On the other hand, the coil patterns 310 and 320 may be formed in multiple layers. A plurality of coil patterns may be formed on the upper side of the coil pattern 310 formed on the upper side of the base material 200 and a plurality of coil patterns may be formed on the lower side of the coil pattern 320 formed on the lower side of the base material 200 May be formed. When the coil patterns 310 and 320 are formed in multiple layers, an insulating layer is formed between the lower layer and the upper layer, and conductive vias (not shown) are formed in the insulating layer to connect the multilayer coil patterns.

The external electrodes 400 may be formed at both ends of the body 100. For example, the external electrodes 400 may be formed on two sides facing each other in the major axis direction of the body 100. The external electrode 400 may be electrically connected to the coil patterns 310 and 320 of the body 100. That is, at least one end of the coil patterns 310 and 320 may be exposed to the outside of the body 100 and the external electrodes 400 may be connected to the ends of the coil patterns 310 and 320. The external electrode 400 may be formed at both ends of the body 100 by various methods such as immersion of the body 100 in a conductive paste or printing, vapor deposition and sputtering. The external electrode 400 may be formed of an electrically conductive metal, and may be formed of at least one metal selected from the group consisting of gold, silver, platinum, copper, nickel, palladium, and alloys thereof. The outer electrode 400 may further include a nickel-plated layer (not shown) or a tin plating layer (not shown) on its surface.

An insulating layer 500 may be further formed between the coil patterns 310 and 320 and the body 100 to insulate the coil patterns 310 and 320 from the metal powder 110. [ That is, the insulating layer 500 may be formed on the upper and lower portions of the substrate 200 so as to cover the coil patterns 310 and 320. The insulating layer 500 may include one or more materials selected from the group consisting of epoxy, polyimide, and liquid crystal crystalline polymers. That is, the insulating layer 500 may be formed of the same material as the polymer 120 forming the body 100. In addition, the insulating layer 500 can be formed on the coil patterns 310 and 320 using an insulating sheet.

As described above, the power inductor according to one embodiment of the present invention can include the metal powder 110, the polymer 120, and the thermally conductive filler 130 to fabricate the body 100. The heat of the body 100 due to the heating of the metal powder 110 can be discharged to the outside by including the thermally conductive filler 130 in the body 100 and the temperature rise of the body 100 can be prevented, It is possible to prevent problems such as lowering of the inductance. Further, by forming the base material 200 inside the body 100 from a metal magnetic material, it is possible to prevent the reduction of the magnetic permeability of the power inductor.

3 to 5 are sectional views sequentially illustrating a method of manufacturing a power inductor according to an embodiment of the present invention.

Referring to FIG. 3, coil patterns 310 and 320 having a predetermined shape are formed on at least one surface, preferably one surface and the other surface, of the base material 200. The substrate 200 may be made of CCL or a metal magnetic material, and it is preferable to use a metal magnetic material capable of increasing the effective permeability and facilitating the capacity implementation. For example, the base material 200 can be manufactured by bonding a copper foil to one surface and the other surface of a metal plate having a predetermined thickness made of a metal alloy containing iron. The coil patterns 310 and 320 may be formed in a coil pattern formed in a circular spiral shape from a predetermined region of the base 200, for example, a central portion. At this time, a coil pattern 310 is formed on one surface of the base material 200, conductive vias are formed through the predetermined region of the base material 200 and conductive material is buried therein, (320). The conductive vias may be formed by forming a via hole in the thickness direction of the substrate 200 using a laser or the like, and then filling the via hole with a conductive paste. The coil pattern 310 may be formed, for example, by a plating process. For this purpose, a photoresist pattern having a predetermined shape is formed on one surface of the substrate 200, a plating process using a copper foil on the substrate 200 as a seed, To grow a metal layer from the surface of the exposed substrate 200, and then removing the photoresist layer. Of course, the coil pattern 320 may be formed on the other surface of the base material 200 in the same manner as the coil pattern 310. On the other hand, the coil patterns 310 and 320 may be formed in multiple layers. When the coil patterns 310 and 320 are formed in multiple layers, an insulating layer is formed between the lower layer and the upper layer, and conductive vias (not shown) are formed in the insulating layer to connect the multilayer coil patterns. After the coil patterns 310 and 320 are formed on one surface and the other surface of the substrate 200, the insulating layer 500 is formed to cover the coil patterns 310 and 320. The insulating layer 500 can be formed by bringing a sheet containing at least one material selected from the group consisting of epoxy, polyimide, and liquid crystal crystalline polymer onto the coil patterns 310 and 320.

Referring to FIG. 4, a plurality of sheets 100a to 100h made of a material including a metal powder 110, a polymer 120, and a thermally conductive filler 130 are provided. Here, the metal powder 110 may be a metal material including iron (Fe), and the polymer 120 may be an epoxy, polyimide, or the like that can insulate the metal powders 110, The filler 130 may be made of MgO, AlN, or a carbon-based material capable of releasing heat of the metal powder 110 to the outside. Further, the surface of the metal powder 110 may be coated with a magnetic material, for example, a metal oxide magnetic material. The thermally conductive filler 130 may be contained in an amount of 0.5 wt% to 3 wt% based on 100 wt% of the metal powder 110. The thermally conductive filler 130 may be contained in an amount of 2.0 wt% to 5.0 wt% . The plurality of sheets 100a to 100h are disposed on the upper and lower portions of the substrate 200 on which the coil patterns 310 and 320 are formed, respectively. On the other hand, the contents of the thermally conductive fillers 130 may be different from each other in the plurality of sheets 100a to 100h. For example, the content of the thermally conductive filler 130 may be increased from one side of the base material 200 and from the other side toward the upper side and the lower side. That is, the content of the thermally conductive filler 130 of the sheets 100b and 100e positioned on the upper side and the lower side of the sheets 100a and 100d in contact with the substrate 200 is smaller than the content of the thermally conductive fillers 130 of the sheets 100a and 100d. The content of the thermally conductive filler 130 of the sheets 100c and 100f located above and below the sheets 100b and 100e is higher than the content of the thermally conductive filler 130 of the sheets 100b and 100e, Can be higher. As the content of the thermally conductive filler 130 increases from the substrate 200, the heat transfer efficiency can be further improved.

Referring to FIG. 5, a plurality of sheets 100a to 100h are laminated and pressed together with a substrate 200 therebetween, and then formed to form a body 100. The external electrodes 400 may be formed on both ends of the body 100 so as to be electrically connected to the drawn portions of the coil patterns 310 and 320. The external electrode 400 may be formed by dipping the body 100 into a conductive paste or by printing a conductive paste on both ends of the body 10 or by a method such as vapor deposition or sputtering. Here, the conductive paste may be a metal material that can impart electrical conductivity to the external electrode 400. Further, a nickel plating layer and a tin plating layer may be further formed on the surface of the external electrode 400 if necessary.

The present invention is not limited to the above-described embodiments, but may be embodied in various forms. In other words, the above-described embodiments are provided so that the disclosure of the present invention is complete, and those skilled in the art will fully understand the scope of the invention, and the scope of the present invention should be understood by the appended claims .

100: Body 200: Base
310. 320: coil pattern 400: external electrode
500: insulating layer

Claims (10)

A body comprising a plurality of metal powders and a polymer;
A base provided within the body;
A coil pattern provided on at least one side of the substrate;
And an external electrode formed outside the body and connected to the coil pattern,
Wherein the body further comprises a thermally conductive filler for discharging the heat of the metal powder to the outside,
Wherein the thermally conductive filler is different in content of at least one region from another region.
The power inductor of claim 1, wherein the metal powder comprises at least one material having at least two sizes.
The power inductor of claim 1, wherein the thermally conductive filler is formed of a material different from the metal powder.
The power inductor of claim 1, wherein the polymer is contained in an amount less than the metal powder.
The power inductor of claim 1, wherein the thermally conductive filler is included in the same or different amount as the polymer.
The power inductor of claim 1, wherein the coil pattern is formed by a plating process and is formed on one surface and the other surface of the substrate, respectively, and is connected through conductive vias formed in the substrate.
The power inductor of claim 1, wherein at least a portion of the outer electrode is formed of the same material as the coil pattern.
The power inductor of claim 7, wherein at least a portion of the external electrode is plated. body;
A base provided within the body; And
And a coil pattern provided on at least one side of the substrate,
Wherein the body comprises at least three or more materials of different function.
10. The power inductor of claim 9, wherein the body comprises a first material having a predetermined permeability, a second material for externally discharging the heat of the body, and a third material for insulating the first and second materials.

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