Magnetic composite sheet and coil assembly

Abstract

This invention provides a magnetic composite sheet and a coil assembly. The coil assembly includes a body and a coil portion, the coil portion being embedded in the body. The body comprises: a first magnetic metal powder particle containing a core and an oxide film, the core being represented by Formula 1 below, the oxide film comprising at least one of silicon (Si) and chromium (Cr) and formed on the surface of the core; a second magnetic metal powder particle having a diameter larger than that of the first magnetic metal powder particle; and a third magnetic metal powder particle having a diameter larger than that of the second magnetic metal powder particle. [Formula 1] Fe a Si b Cr c Among them, 3 at%≤b≤6 at%, 2.65 at%≤c≤3.65 at%, and a+b+c=100 at.

Description

[0001] This application is a divisional application of the invention patent application filed on September 14, 2020, with application number 202010960009.2 and invention title "Magnetic Composite Sheet and Coil Assembly". Technical Field

[0002] This disclosure relates to a magnetic composite sheet and a coil assembly. Background Technology

[0003] An inductor (a type of coil assembly) is a typical passive component used in electronic devices, along with resistors and capacitors.

[0004] For a thin-film coil assembly (one type of coil assembly), the body is formed by forming a coil portion on at least one surface of a substrate, followed by stacking a magnetic composite sheet containing magnetic metal powder particles on the substrate.

[0005] Regarding the above situation, it is possible to use a magnetic composite sheet containing two or more magnetic metal powder particles with different diameters to form the body, in order to improve the characteristics of the coil assembly by increasing the percentage of the magnetic body (magnetic metal powder particles) of the body.

[0006] As the diameter of the magnetic metal powder particles decreases, it becomes more difficult to form an insulating film on the surface of the magnetic metal powder particles, thus reducing the insulation resistance of the bulk.

[0007] Furthermore, when the filling rate of magnetic metal powder particles is increased to increase the percentage of magnetic body in the main body, the overall insulation resistance of the main body will decrease due to the reduced distance between the magnetic metal powder particles. Summary of the Invention

[0008] One aspect of this disclosure provides a coil assembly and a magnetic composite sheet capable of easily reducing leakage current in a coil assembly comprising at least three types of magnetic metal powder particles with different diameters.

[0009] According to one aspect of this disclosure, a coil assembly includes: a body and a coil portion embedded in the body, wherein the body includes: a first magnetic metal powder particle comprising a core and an oxide film, the core comprising a compound represented by Formula 1 below, the oxide film comprising at least one of silicon (Si) and chromium (Cr) and formed on the surface of the core; a second magnetic metal powder particle having a diameter larger than that of the first magnetic metal powder particle; and a third magnetic metal powder particle having a diameter larger than that of the second magnetic metal powder particle. [Formula 1] Fe a Si b Crc Among them, 3 at%≤b≤6 at%, 2.65 at%≤c≤3.65 at%, and a+b+c=100 at.

[0010] According to one aspect of this disclosure, a magnetic composite sheet comprises: first magnetic metal powder particles including a core and an oxide film, the core comprising a compound represented by Formula 1 below, the oxide film comprising at least one of silicon and chromium and formed on the surface of the core; second magnetic metal powder particles having a diameter larger than that of the first magnetic metal powder particles; third magnetic metal powder particles having a diameter larger than that of the second magnetic metal powder particles; and an insulating resin. [Formula 1] Fe a Si b Cr c Among them, 3 at%≤b≤6 at%, 2.65 at%≤c≤3.65 at%, and a+b+c=100 at. Attached Figure Description

[0011] The above and other aspects, features and advantages of this disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Figure 1 This is a schematic diagram illustrating a coil assembly according to an exemplary embodiment of the present disclosure; Figure 2 It is along Figure 1 Line II A cross-sectional view taken from the section; Figure 3 It is along Figure 1 Line II-II A cross-sectional view taken from the section; Figure 4 for Figure 2 An enlarged image of the letter "A"; Figure 5 for Figure 2 An enlarged view of the letter "B"; Figure 6 yes Figure 2 Examples of variations of the letter "B"; Figure 7 This is a schematic diagram illustrating a coil assembly according to another exemplary embodiment; Figure 8 This shows the view from below. Figure 7 A diagram of the coil assembly; Figure 9 This is shown according to test example 3 and along Figure 1A schematic diagram of the coil assembly corresponding to the cross section taken by line I-I'; Figure 10 It is along Figure 7 Line III-III A cross-sectional view taken from the section; Figure 11 This is a schematic diagram illustrating a magnetic composite sheet according to an exemplary embodiment; and Figure 12 yes Figure 11 An enlarged view of the "C". Detailed Implementation

[0012] In the following text, the terminology used with respect to the elements of this disclosure is named in consideration of the function of each element and should therefore not be construed as limiting the scope to the technical elements of this disclosure. As used herein, the singular form may include the plural form unless the context clearly indicates otherwise. Furthermore, as used herein, the terms “comprising,” “having,” and variations thereof denote a feature, quantity, step, operation, element, component, or combination thereof, and should not be construed as excluding the possibility of the presence or addition of one or more other features, quantities, steps, operations, elements, components, or combinations thereof. Additionally, the term “on” does not necessarily mean that any element is located on an upper side based on the direction of gravity, but rather that any element is located above or below the target portion.

[0013] Throughout this specification, it will be understood that when an element or layer is referred to as being “connected to” or “combined to” another element or layer, it can be understood as being “directly connected to” or “directly combined to” another element or layer, or that there may be an intermediate element or layer. It will be further understood that the terms “comprising” and / or “including” specify the presence of an element, but do not preclude the presence or addition of one or more other elements.

[0014] The dimensions and thicknesses of each component shown in the accompanying drawings are for illustrative purposes only, and this disclosure is not intended to be limited thereto.

[0015] In the accompanying drawings, the term "W direction" may refer to the "first direction" or the "width direction", the term "L direction" may refer to the "second direction" or the "length direction", and the term "T direction" may refer to the "third direction" or the "thickness direction".

[0016] Values ​​used to describe parameters such as 1-D dimensions of a component (including, but not limited to, "length", "width", "thickness", "diameter", "distance", "gap" and / or "size"), 2-D dimensions of a component (including, but not limited to, "area" and / or "size"), 3-D dimensions of a component (including, but not limited to, "volume" and / or "size"), and properties of a component (including, but not limited to, "roughness", "density", "weight", "weight ratio" and / or "molar ratio") can be obtained by the methods and / or tools described in this disclosure. However, this disclosure is not limited thereto. Other methods and / or tools, as understood by one of ordinary skill in the art, may be used even if not described in this disclosure.

[0017] In electronic devices, various types of electronic components can be used, and various types of coil assemblies can be appropriately used between electronic components to remove noise or for other purposes.

[0018] In other words, coil components in electronic devices can be used as power inductors, high-frequency inductors, ordinary ferrite beads, high-frequency (GHz) ferrite beads, common-mode filters, etc.

[0019] In the following, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Identical or corresponding components are given the same reference numerals and will not be further explained.

[0020] Figure 1 This is a schematic diagram illustrating a coil assembly according to an exemplary embodiment of the present disclosure. Figure 2 It is along Figure 1 The cross-sectional view taken from line I-I'. Figure 3 It is along Figure 1 The cross-sectional view taken from line II-II', and Figure 4 yes Figure 2 An enlarged image of the letter "A", and Figure 5 yes Figure 2 An enlarged view of the letter "B". Figure 6 yes Figure 2 Examples of variations of the letter "B".

[0021] based on Figures 1 to 6 According to an exemplary embodiment, the coil assembly 1000 includes a body 100, an insulating substrate 200, a coil portion 300, and external electrodes 400 and 500, and may also include an insulating film 600.

[0022] The main body 100 can form the appearance of the coil assembly 1000, and the coil portion 300 can be embedded in the main body 100.

[0023] The main body 100 may have a hexahedral shape.

[0024] based on Figures 1 to 3The main body 100 may include a first surface 101 and a second surface 102 opposite to each other in the length direction L, a third surface 103 and a fourth surface 104 opposite to each other in the width direction W, and a fifth surface 105 and a sixth surface 106 opposite to each other in the thickness direction T. The first surface 101 to the fourth surface 104 of the main body 100 may be a wall of the main body 100 connecting the fifth surface 105 and the sixth surface 106 of the main body 100. In the following description, the expression "two end surfaces of the main body" may refer to the first surface 101 and the second surface 102 of the main body 100, and the expression "two side surfaces of the main body" may refer to the third surface 103 and the fourth surface 104 of the main body 100, while the expression "one surface of the main body" may refer to the sixth surface 106 of the main body 100, and the expression "another surface of the main body" may refer to the fifth surface 105 of the main body. In addition, the expression "upper surface and lower surface of the main body" may refer to the upper and lower surfaces of the main body 100 relative to each other. Figures 1 to 3 The fifth surface 105 and the sixth surface 106 are defined by the direction.

[0025] The body 100 may be configured such that the coil assembly 1000, including external electrodes 400 and 500 according to an exemplary embodiment, has a thickness of 0.85 mm or less. As an example, the body 100 may be configured such that the coil assembly 1000 in which the external electrodes 400 and 500 are formed has a length of 2.0 mm, a width of 1.2 mm, and a thickness of 0.85 mm. Optionally, the body may be configured such that the coil assembly 1000 in which the external electrodes 400 and 500 are formed has a length of 2.0 mm, a width of 1.6 mm, and a thickness of 0.55 mm, or a length of 2.0 mm, a width of 1.2 mm, and a thickness of 0.55 mm. Optionally, the body may be configured such that the coil assembly 1000 in which the external electrodes 400 and 500 are formed has a length of 1.2 mm, a width of 1.0 mm, and a thickness of 0.55 mm, but is not limited thereto. The dimensions of the coil assembly 1000 specified above are merely examples, and therefore, this disclosure is not limited thereto. A component with a total thickness of 0.85 mm or less also falls within the scope of this disclosure. In the previously described examples, no process tolerances were applied to each value of width and thickness. When compared with the values ​​above, cases with differences that can be identified as process tolerances fall within the scope of this disclosure.

[0026] The thickness of the coil assembly can be obtained by measuring the thickness of the assembly using a micrometer. The thickness of the assembly can refer to the arithmetic mean of the thicknesses of multiple assemblies (e.g., 30). The thickness of each assembly is obtained using the micrometer method described above. The length and width of the coil assembly can be obtained using both the micrometer method and the arithmetic mean method described above. Alternatively, the length, width, and thickness of the coil assembly can also be measured using methods different from the micrometer method, as understood by those skilled in the art.

[0027] The body 100 may comprise magnetic metal powder particles 11 to 13 and insulating resin R. Specifically, the body 100 may be formed by laminating one or more magnetic composite sheets comprising magnetic metal powder particles 11 to 13 dispersed in resin R, and then curing the magnetic composite sheets. The magnetic metal powder particles 11 to 13 comprise a first magnetic metal powder particle 11, a second magnetic metal powder particle 12 having a diameter larger than that of the first magnetic metal powder particle 11, and a third magnetic metal powder particle 13 having a diameter larger than that of the second magnetic metal powder particle 12. In this exemplary embodiment, since the body 100 comprises three or more types of magnetic metal powder particles 11 to 13 with different diameters, the magnetic body filling rate of the body 100 can be enhanced, and the characteristics of the component (such as inductance) can be improved. As used herein, the term "diameter" for magnetic metal powder particles 11 to 13 may refer to particle distribution (such as D). 50 Or D 90 Therefore, the different diameters of magnetic metal powder particles 11 to 13 can refer to the particle distribution (such as D). 50 Or D 90 (different values).

[0028] The insulating resin R may contain epoxy resin, polyimide, liquid crystal polymer, or mixtures thereof, but is not limited thereto.

[0029] The first magnetic metal powder particle 11, the second magnetic metal powder particle 12, and the third magnetic metal powder particle 13 are described below.

[0030] The second magnetic metal powder particle 12 and the third magnetic metal powder particle 13 respectively comprise magnetic metal particles 12-1 and 13-1 and insulating coatings 12-2 and 13-2 surrounding the magnetic metal particles 12-1 and 13-1 and comprising insulating resin R'. The insulating resin R' may be the same as or different from the material of the insulating resin R included in the body, and the insulating resin R' fills all the space not occupied by the first magnetic metal powder particle, the second magnetic metal powder particle, and the third magnetic metal powder particle.

[0031] Magnetic metal particles 12-1 and 13-1 may comprise at least one selected from the group consisting of iron (Fe), silicon (Si), chromium (Cr), cobalt (Co), molybdenum (Mo), aluminum (Al), niobium (Nb), copper (Cu), boron (B), and nickel (Ni). For example, each of magnetic metal particles 12-1 and 13-1 may be an Fe-Si-B-Nb-Cu based alloy powder.

[0032] Magnetic metal particles 12-1 and 13-1 may contain at least one selected from the group consisting of Fe, Si, Cr, Co, Mo, Al, Nb, Cu, and Ni. For example, magnetic metal particles 12-1 and 13-1 may contain at least one of pure iron powder, Fe-Si alloy powder, Fe-Si-Al alloy powder, Fe-Ni alloy powder, Fe-Ni-Mo alloy powder, Fe-Ni-Mo-Cu alloy powder, Fe-Co alloy powder, Fe-Ni-Co alloy powder, Fe-Cr alloy powder, Fe-Cr-Si alloy powder, Fe-Si-Cu-Nb alloy powder, Fe-Ni-Cr alloy powder, Fe-Cr-Al alloy powder, or Fe-Si-B-Nb-Cu alloy powder.

[0033] The magnetic metal particles 12-1 and 13-1 can be amorphous or crystalline. For example, the magnetic metal particles 12-1 and 13-1 can be Fe-Si-B-Nb-Cu alloy powder, and can be grains containing iron silicide (Fe3Si) in an amorphous matrix, but are not limited thereto.

[0034] Insulating coatings 12-2 and 13-2 may comprise an electrically insulating resin, such as epoxy resin or polyimide resin, but are not limited thereto. Insulating coatings 12-2 and 13-2 may have a thickness greater than 0.01 μm and less than 1 μm, but are not limited thereto. The thickness of insulating coating 12-2 can be obtained by the arithmetic mean of the thicknesses of insulating coating 12-2 on a specific particle of the second magnetic metal powder particles shown in the SEM or TEM image. Insulating coatings 12-2 and 13-2 can be formed on the surface of magnetic metal particles 12-1 and 13-1 by immersing magnetic metal particles 12-1 and 13-1 in a liquid insulating resin and drying the magnetic metal particles 12-1 and 13-1, but are not limited thereto. The thickness can be measured by methods other than those using SEM or TEM images, as understood by those skilled in the art.

[0035] The diameter of the second magnetic metal powder particle 12 may be larger than the diameter of the first magnetic metal powder particle 11, and the diameter of the third magnetic metal powder particle 13 may be larger than the diameter of the second magnetic metal powder particle 12. As an example, the diameter of the first magnetic metal powder particle 11 may be less than 1 μm. More preferably, the diameter of the first magnetic metal powder particle 11 may be 0.1 μm to 0.2 μm. The diameter of the second magnetic metal powder particle 12 may be 1 μm to 2 μm, and the diameter of the third magnetic metal powder particle 13 may be 25 μm to 30 μm. When the diameter of the second magnetic metal powder particle 12 exceeds the aforementioned range, the magnetic fill percentage of the body 100 may decrease. When the diameter of the third magnetic metal powder particle 13 is less than 25 μm, the magnetic fill percentage of the body 100 may decrease. When the diameter of the third magnetic metal powder particles 13 exceeds 30 μm, the appearance defects may increase, and the bonding force between the outer electrodes 400 and 500 and the body 100 may decrease. Meanwhile, plating diffusion may occur during the plating of the outer electrodes 400 and 500.

[0036] The first magnetic metal powder particle 11 includes a core 11-1 represented by the following formula 1, and an oxide film 11-2 formed on the surface of the core 11-1 and comprising at least one of Si and Cr: [Formula 1] Fe a Si b Cr c Among them, 3 at%≤b≤6 at%, 2.65 at%≤c≤3.65 at%, and a+b+c=100 at.

[0037] For a three-peak coil assembly (meaning the coil assembly contains three types of magnetic metal powder particles with different diameters), an insulating coating can be easily and readily formed on the surfaces of the magnetic metal powder particles with the largest diameter (coarse magnetic metal powder particles) and those with an intermediate diameter (fine magnetic metal powder particles) (due to their relatively large diameter) using a liquid-phase process. Conversely, due to current liquid-phase methods, it is difficult to form an insulating coating on the surfaces of magnetic metal powder particles with the smallest diameter (less than 1 μm; ultrafine magnetic metal powder particles). Leakage voltage may be reduced due to short circuits between ultrafine magnetic metal powder particles.

[0038] In this disclosure, the aforementioned problem is solved by a first magnetic metal powder particle 11 (ultrafine magnetic metal powder particle) forming a core 11-1 and an oxide film 11-2 having its own oxide surface on the surface of the core 11-1. For example, the oxide film 11-2 in the first magnetic metal powder particle 11 can be deposited on the surface of the core 11-1. The oxide film 11-2 is a native oxide and therefore may contain at least one of Si and Cr contained in the core 11-1. That is, the oxide film 11-2 may contain at least one of Si-O bonds or Cr-O bonds. In this disclosure, since the first magnetic metal powder particle 11 contains a core 11-1 and an oxide film 11-2 as a native oxide of the core 11-1, the insulation resistance of the first magnetic metal powder particle 11 can be obtained by a relatively easy method.

[0039] By satisfying the composition of Formula 1, an oxide film 11-2 with enhanced insulation resistance characteristics can be formed on the surface of the core 11-1. When the Si content (at%) of the core 11-1 is less than the range of Formula 1, the oxide film 11-2 is insufficient to form on the surface of the core 11-1, resulting in a decrease in insulation resistance. This will be described below. When the Si content (at%) of the core 11-1 exceeds the range of Formula 1, the volume occupied by the oxide film 11-2 in the entire first magnetic metal powder particle 11 increases significantly, and component characteristics (such as inductance) may decrease.

[0040] The main body 100 includes a core 110 that extends through the coil portion 300, as will be described below. The core 110 may be formed, but is not limited to, by filling the through hole of the coil portion 300 with at least a portion of the magnetic composite sheet in a process of stacking and curing the magnetic composite sheet.

[0041] The insulating substrate 200 is embedded in the main body 100. The insulating substrate 200 is configured to support the coil portion 300.

[0042] The insulating substrate 200 is formed using an insulating material such as a thermosetting insulating resin (e.g., epoxy resin), a thermoplastic insulating resin (e.g., polyimide), or a photosensitive insulating resin, or it can be formed using an insulating material in which a reinforcing material (e.g., glass fiber or inorganic filler) is impregnated with such an insulating resin. For example, the insulating substrate 200 can be formed using insulating materials such as prepreg, Ajinomoto Build-up Film (ABF), FR-4, bismaleimide triazine (BT) film, photosensitive dielectric (PID) film, etc., but examples of materials for the inner insulating layer are not limited to these.

[0043] One or more of the following can be used as inorganic fillers: silicon dioxide (SiO2), aluminum oxide (Al2O3), silicon carbide (SiC), barium sulfate (BaSO4), talc, mud, mica powder, aluminum hydroxide (Al(OH)3), magnesium hydroxide (Mg(OH)2), calcium carbonate (CaCO3), magnesium carbonate (MgCO3), magnesium oxide (MgO), boron nitride (BN), aluminum borate (AlBO3), barium titanate (BaTiO3), and calcium zirconate (CaZrO3).

[0044] When the insulating substrate 200 is formed using an insulating material including reinforcing material, the insulating substrate 200 provides improved rigidity. When the insulating substrate 200 is formed using an insulating material that does not include glass fiber, the insulating substrate 200 facilitates the miniaturization of the component. When the insulating substrate 200 is formed using an insulating material including a photosensitive insulating resin, the number of processes used to form the coil portion 300 can be reduced, thereby reducing manufacturing costs and facilitating the formation of fine vias 320.

[0045] The coil portion 300 includes planar helical coil patterns 311 and 312, and the coil portion 300 is embedded in the body 100 to present the characteristics of the coil assembly. For example, when the coil assembly 1000 is used as a power inductor, the coil portion 300 can store an electric field as a magnetic field to maintain the output voltage, thereby stabilizing the power of the electronic device.

[0046] The coil portion 300 may include coil patterns 311 and 312 and a via 320. Specifically, based on Figures 1 to 3 In the direction of the first coil pattern 311, a second coil pattern 312 is disposed on the lower surface of the sixth surface 106 of the insulating substrate 200 facing the body 100, while a third coil pattern 312 is disposed on the upper surface of the insulating substrate. A through-hole 320 penetrates the insulating substrate 200 to contact the inner ends of the first coil pattern 311 and the second coil pattern 312. This allows the coil portion 300 to be used as a single coil formed based on the core 110, with one or more turns.

[0047] The first coil pattern 311 and the second coil pattern 312 have a planar spiral shape in which at least one turn is formed based on the core 110. As an example, the first coil pattern 311 may be relative to... Figures 1 to 3 The direction is formed on the lower surface of the insulating substrate 200 based on the core 110 to form at least one turn.

[0048] The outer ends of the first coil pattern 311 and the second coil pattern 312 are exposed on the first surface 101 and the second surface 102, respectively, to contact the first external electrode 400 and the second external electrode 500. That is, the outer end of the first coil pattern 311 is connected to the first external electrode 400, and the outer end of the second coil pattern 312 is connected to the second external electrode 500.

[0049] The first coil pattern 311 includes based on Figure 5 and Figure 6 The first conductive layer 311a and the second conductive layer 311b are formed on the lower surface of the insulating substrate 200 in the direction of contact.

[0050] The first conductive layer 311a can serve as a seed layer for forming the second conductive layer 311b by electroplating. The first conductive layer 311a (the seed layer of the second conductive layer 311b) is formed to be thinner than the second conductive layer 311b. The first conductive layer 311a can be formed by an electroless plating process, such as a thin-film process like sputtering. When the first conductive layer 311a is formed by a thin-film process such as sputtering, at least a portion of the material forming the first conductive layer 311a can penetrate into the lower surface of the insulating substrate 200. This can be demonstrated by the fact that a difference in the concentration of the metal material forming the first conductive layer 311a occurs along the thickness direction T of the body 100 in the insulating substrate 200.

[0051] The thickness of the first conductive layer 311a can be from 1.5 μm to 3 μm. When the thickness of the first conductive layer 311a is less than 1.5 μm, it is difficult to implement, which may lead to plating defects in subsequent processes. When the thickness of the first conductive layer 311a is greater than 3 μm, it is difficult to form a second conductive layer 311b with a relatively large volume within the limited volume of the body 100. For example, based on any turn of the first coil pattern 311 shown in an optical micrograph of a length-thickness section (LT section) in the central portion of the body 100 along the width direction W, the thickness of the first conductive layer 311a can be defined as the thickness of the first conductive layer 311a when the normal along the thickness direction T originates from a surface of the insulating substrate 200 that contacts the first conductive layer 311a (based on...). Figure 5 , Figure 6 The distance from a point on a line segment corresponding to one surface of the insulating substrate 200 in the direction of the middle is the distance from that point to another point on a line segment corresponding to the other surface of the first conductive layer 311a that is opposite to one surface of the first conductive layer 311a.

[0052] Optionally, for example, based on an optical micrograph of any one turn of the first coil pattern 311 shown in a length-thickness section (LT section) in the central portion of the body along the width direction W, when multiple normals along the thickness direction T from one surface of the contact insulating substrate 200 with the first conductive layer 311a (based on Figure 5 , Figure 6When a line segment corresponding to one surface of the insulating substrate 200 in the direction of the middle extends to multiple points, the thickness of the first conductive layer 311a can indicate the arithmetic mean of the distances from the multiple points to multiple other points where the line segment corresponding to the other surface of the first conductive layer 311a opposite to one surface of the first conductive layer 311a contacts.

[0053] Optionally, based on an optical micrograph of a length-thickness section (LT section) in the central portion of the body along the width direction W, the thickness of the first conductive layer 311a may refer to the arithmetic mean of the individual thicknesses of the multiple turns shown in the cross-sectional image by the method described above.

[0054] Thickness can be measured by methods other than those described above, as understood by those skilled in the art.

[0055] based on Figure 5 In some embodiments, at least a portion of the side surface of the first conductive layer 311a is exposed through the second conductive layer 311b. Figure 5 In this case, a seed film for forming the first conductive layer 311a is formed on the entire lower surface of the insulating substrate 200, and a resist for forming the second conductive layer 311b is formed on the seed film. The second conductive layer 311b is then formed by electroplating, followed by removal of the resist and selective removal of the seed film on which the second conductive layer 311b is not formed, resulting in the formation of the first coil pattern 311. Therefore, at least a portion of the side surface of the first conductive layer 311a formed by the selectively removed seed film is not covered by the second conductive layer 311b, but is exposed from the second conductive layer 311b. The seed film can be formed on the lower surface of the insulating substrate 200 by electroless plating or sputtering. Optionally, the seed film can be copper foil of a copper-clad laminate (CCL). The resist can be formed by coating the seed film with a material for forming the resist and then performing a photolithography process. After the photolithography process, the resist can have openings corresponding to the areas where the second conductive layer 311b will be formed. The selective removal of the seed film can be performed by laser processing and / or etching processes. When the seed film is selectively removed by etching, the first conductive layer 311a can be formed in a form in which the cross-sectional area increases as the second conductive layer 311b approaches the insulating substrate 200.

[0056] based on Figure 6 In some embodiments, the second conductive layer 311b covers the first conductive layer 311a. Figure 5 compared to, Figure 6The present invention relates to forming a first conductive layer 311a with a planar spiral on the lower surface of an insulating substrate 200 by electroplating, and forming a second conductive layer 311b on the first conductive layer 311a. When the second conductive layer 311b is formed by anisotropic plating, a plating resist may not be used, but the present disclosure is not limited thereto. That is, when forming the second conductive layer 311b, a plating resist for forming the second conductive layer may be used. An opening exposing the first conductive layer 311a is formed in the plating resist used to form the second conductive layer. The diameter of the opening may be larger than the linewidth of the first conductive layer 311a, resulting in the second conductive layer 311b filling the opening and covering the side surfaces of the first conductive layers 311a and 312a to contact the insulating substrate 200.

[0057] Furthermore, the above description of the first conductive layer 311a and the second conductive layer 311b of the first coil pattern 311 can be similarly applied to the first conductive layer 312a and the second conductive layer 312b of the second coil pattern 312.

[0058] Via 320 may include at least one conductive layer. As an example, when via 320 is formed by electroplating, via 320 may include a seed layer formed on the inner wall of a via hole penetrating the insulating substrate 200 and an electroplated layer filling the via hole in which the seed layer is formed. The seed layer of via 320 may be integrally formed with the first conductive layers 311a and 312a in the same process, or formed in different processes to form a boundary between them. The electroplated layer of via 320 may be integrally formed with the second conductive layers 311b and 312b in the same process, or formed in different processes to form a boundary between them.

[0059] When the linewidths of coil patterns 311 and 312 are very large, the volume occupied by the magnetic body in the main body 100 decreases, thereby negatively affecting the inductance. As a non-limiting example, the aspect ratio (AR) of coil patterns 311 and 312 can be from 3:1 to 9:1.

[0060] The coil patterns 311 and 312 and the via 320 can be formed using Cu, Al, Ag, Sn, Au, Ni, Pd, Ti, Cr, or alloys thereof, but are not limited thereto. As a non-limiting example, when the first conductive layers 311a and 312a are formed by sputtering and the second conductive layers 311b and 312b are formed by electroplating, the first conductive layers 311a and 312a may contain at least one of Mo, Cr, Cu, and Ti, while the second conductive layers 311b and 312b may contain Cu. As another non-limiting example, when the first conductive layers 311a and 312a are formed by electroless plating and the second conductive layers 311b and 312b are formed by electroplating, the first conductive layers 311a and 312a and the second conductive layers 311b and 312b may contain Cu. In this case, the Cu density in the first conductive layers 311a and 312a may be lower than the Cu density in the second conductive layers 311b and 312b.

[0061] External electrodes 400 and 500 are disposed on the surface of the body 100 and connected to the two ends of the coil portion 300. In this exemplary embodiment, the two ends of the coil portion 300 are exposed to the first surface 101 and the second surface 102 of the body 100, respectively. Therefore, the first external electrode 400 is disposed on the first surface 101 to contact and connect to the end of the first coil pattern 311 exposed to the first surface 101 of the body, while the second external electrode 500 is disposed on the second surface 102 to contact and connect to the end of the second coil pattern 312 exposed to the second surface 102 of the body 100.

[0062] The external electrodes 400 and 500 may be formed using conductive materials (such as Cu, Al, Ag, Sn, Au, Ni, Pd, Ti or alloys thereof), but are not limited thereto.

[0063] The external electrodes 400 and 500 can be formed in a single layer or multiple layers. As an example, the first external electrode 400 can be formed having a first layer containing Cu, a second layer disposed on the first layer and containing Ni, and a third layer disposed on the second layer and containing Sn. The first to third layers can be formed by plating, but are not limited thereto. As another example, the first electrode layer 400 may include a resin electrode layer containing conductive powder and resin, and a plating layer plated on the resin electrode layer. In this case, the resin electrode layer may contain a cured product of a thermosetting resin and at least one conductive powder selected from Cu and Ag. Furthermore, the plating layer may include a first plating layer containing Ni and a second plating layer containing Sn. When the resin contained in the resin electrode layer contains the same resin as the insulating resin R of the body 100, the bonding force between the resin electrode layer and the body 100 can be enhanced.

[0064] An insulating film 500 may be formed on the insulating substrate 200 and the coil portion 300. The insulating film 500 serves to insulate the coil portion 300 from the body 100 and may contain known insulating materials (such as parylene). Any insulating material may be included in the insulating film 600, and there are no particular limitations. The insulating film 600 may be formed by methods such as vapor deposition, but is not limited thereto. The insulating film 600 may be formed by stacking insulating films on both surfaces of the insulating substrate 20. In the former case, the insulating film 600 may be formed as a conformal film along the surfaces of the coil portion 300 and the insulating substrate 200. In this case, at least some of the magnetic metal powder particles 11 to 13 may fill the spaces between turns adjacent to the coil patterns 311 and 312 on which the conformal insulating film 600 is formed. In the latter case, the insulating film 600 may be formed in a manner that fills the spaces between turns adjacent to the coil patterns 311 and 312. Additionally, as previously described, the resist used to form the second conductive layers 311b and 312b can be formed on the insulating substrate 200, and this resist can be permanent and not removed. In this case, the insulating film 600 can be a resist or a permanent photoresist. Furthermore, the insulating film 600 in this disclosure is an optional construction and can therefore be omitted, provided that the body 100 can ensure sufficient insulation resistance under the operating conditions of the coil assembly 1000 according to this exemplary embodiment.

[0065] The following experimental examples 1 to 3 were conducted by preparing a coil assembly comprising a body (including a first magnetic metal powder particle, a second magnetic metal powder particle, and a third magnetic metal powder particle) and simultaneously changing the Si content (at%) in the core of the first magnetic metal powder.

[0066] In Table 1 below, the term "independent leakage voltage" refers to the leakage voltage measured only for the first magnetic metal powder. The term "trimodal leakage voltage" refers to the leakage voltage of the bulk body measured after the bulk body containing the second and third magnetic metal powder particles has been formed.

[0067] In addition, except for the Si content (at%) of core 11-1, Test Examples 1 to 3 are identical. That is, in Test Examples 1 to 3, the diameter and weight percentage (wt%) of the first magnetic metal powder particles are the same (the diameter and weight percentage (wt%) of the second and third magnetic metal powder particles are also the same). Furthermore, the composition of the second and third magnetic metal powder particles is the same in Test Examples 1 to 3. In addition, the second magnetic metal powder has a larger diameter than the first magnetic metal powder particle, and the third magnetic metal powder particle has a larger diameter than the second magnetic metal powder particle. The first magnetic metal powders of Test Examples 1 to 3, including the core represented by Formula 1 except for the silicon content, are specified in Table 1 below.

[0068] [Table 1]

[0069] Based on Table 1, test examples 2 and 3, which satisfy the range of Equation 1, show increased leakage voltage and three-peak leakage voltage, and therefore increased insulation resistance characteristics.

[0070] Specifically, in Experimental Example 1, where the Si content does not satisfy the range of Formula 1, the insulation resistance characteristics are degraded due to insufficient oxide film formation on the surface of the core. However, in Experimental Examples 2 and 3, where the Si content satisfies the range of Formula 1, a silicon oxide film is formed on the surface of the core with sufficient thickness, thereby causing enhanced insulation resistance characteristics of the first magnetic metal powder particles themselves and the three-peaked body containing the first magnetic metal powder particles.

[0071] Figure 7 This is a schematic diagram illustrating a coil assembly according to another exemplary embodiment. Figure 8 This shows the view from below. Figure 7 A diagram of the coil assembly. Figure 9 This is shown according to test example 3 and along Figure 1 A schematic diagram of the coil assembly corresponding to the cross section intercepted by line I-I', and Figure 10 It is along Figure 7 The cross-sectional view taken from line III-III'.

[0072] based on Figures 1 to 6 as well as Figures 7 to 10When compared to the coil assembly 1000 according to the previous exemplary embodiment, the coil assembly 2000 according to this exemplary embodiment differs in terms of the coil portion 300 and the external electrodes 400 and 500. Therefore, the coil portion 300 and the external electrodes 400 and 500 will be described solely based on the differences between them. The description of the remaining configurations in the previous exemplary embodiments may be applied to this exemplary embodiment either as is or with modifications.

[0073] The coil portion 300 applied in this exemplary embodiment includes coil patterns 311 and 312, lead patterns 331 and 332, auxiliary lead patterns 341 and 342, and vias 321, 322, and 323.

[0074] Specifically, based on Figures 7 to 10 In this exemplary embodiment, the first coil pattern 311, the first lead pattern 331, and the second lead pattern 332 are disposed on the lower surface of the sixth surface 106 of the insulating substrate 200 facing the main body, and the second coil pattern 312, the first auxiliary lead pattern 341, and the second auxiliary lead pattern 342 are disposed on the upper surface of the fifth surface 105 of the insulating substrate 200 facing the main body. The lead patterns 331 and 332 of this exemplary embodiment are configured to contact and connect to the external electrodes 400 and 500, similar to the two ends of the first coil pattern 311 and the second coil pattern 312 described in the previous exemplary embodiments.

[0075] based on Figure 7 , Figure 9 and Figure 10 The first coil pattern 311 contacts the first lead pattern 331 on the lower surface of the insulating substrate, and the first coil pattern 311 and the first lead pattern 331 are spaced apart from the second lead pattern 332. The second coil pattern 312 contacts the second auxiliary lead pattern 342 on the upper surface of the insulating substrate 200, and the second coil pattern 312 and the second auxiliary lead pattern 342 are spaced apart from the first auxiliary lead pattern 341. A first via 321 penetrates the insulating substrate 200 to contact the inner ends of the first coil pattern 311 and the second coil pattern 312, a second via 322 penetrates the insulating substrate 200 to contact the first lead pattern 331 and the first auxiliary lead pattern 341, and a third via 323 penetrates the insulating substrate 200 to contact the second lead pattern 332 and the second auxiliary lead pattern 342. This allows the coil portion 300 to be used as a single coil as a whole.

[0076] Lead patterns 331 and 332, as well as auxiliary lead patterns 341 and 342, are exposed on both end surfaces of the body 100. That is, the first lead pattern 331 and the first auxiliary lead pattern 341 are exposed on the first surface 101 of the body 100, and the second lead pattern 332 and the second auxiliary lead pattern 342 are exposed on the second surface 102 of the body 100.

[0077] At least one of the coil patterns 311 and 312, vias 321, 322 and 323, lead patterns 331 and 332, and auxiliary lead patterns 341 and 342 may include at least one conductive layer.

[0078] As an example, when the second coil pattern 312, auxiliary lead patterns 341 and 342, and vias 321, 322, and 323 are formed to be plated on another surface of the insulating substrate 200, each of the second coil pattern 312, auxiliary lead patterns 341 and 342, and vias 321, 322, and 323 may include at least one conductive layer (such as a seed layer and / or an electroplated layer). The seed layer may be an electroless layer. In this case, the electroplated layer may have a single-layer structure or a multi-layer structure. The multi-layer electroplated layer may be formed in the form of a conformal film in which one electroplated layer is covered by another electroplated layer, or in the form of an electroplated layer stacked only on one surface of another electroplated layer. The seed layers of the second coil pattern 312, the auxiliary lead patterns 341 and 342, and the vias 321, 322, and 323 are integrally formed, and therefore may not have boundaries formed between them, but are not limited thereto. The electroplated layer of the second coil pattern 312, the electroplated layers of the auxiliary lead patterns 341 and 342, and the electroplated layers of the vias 321, 322 and 323 are integrally formed, so they may not have boundaries formed between them, but are not limited thereto.

[0079] based on Figure 7 and Figure 10 The coil patterns 311 and 312, lead patterns 331 and 332, and auxiliary lead patterns 341 and 342 may be formed to protrude from the lower and upper surfaces of the insulating substrate 200. As another example, the first coil pattern 311 and lead patterns 331 and 332 are formed to protrude from the lower surface of the insulating substrate 200, and the second coil pattern 312 and auxiliary lead patterns 341 and 342 are embedded in the upper surface of the insulating substrate 200, such that the upper surface of each of the second coil pattern 312 and auxiliary lead patterns 341 and 342 is exposed on the upper surface of the insulating substrate 200. In this case, a recess is formed on the upper surface of the insulating substrate 200, such that the lower surface of the second coil pattern 312 and / or the auxiliary lead patterns 341 and 342 is not on the same plane as the upper surface of the insulating substrate 200. As another example, the second coil pattern 312 and the auxiliary lead patterns 341 and 342 are formed to protrude from the upper surface of the insulating substrate 200, and the first coil pattern 311 and the lead patterns 331 and 332 are embedded in the lower surface of the insulating substrate 200, such that the lower surface of each of the first coil pattern 311 and the lead patterns 331 and 332 is exposed to the lower surface of the insulating substrate 200.

[0080] Coil patterns 311 and 312, lead patterns 331 and 332, auxiliary lead patterns 341 and 342, and vias 321, 322, and 323 may be formed using conductive materials such as Cu, Al, Ag, Sn, Au, Ni, Pd, Ti, or alloys thereof, but are not limited thereto.

[0081] In addition, based on Figure 9 The electrical connection between the auxiliary lead pattern 341 and the rest of the coil portion 300 is unrelated and can therefore be omitted. However, it is preferable to form the first auxiliary lead pattern 341 to skip the process of distinguishing the fifth and sixth surfaces of the body 100.

[0082] The first external electrode 400 and the second external electrode 500 include a first connecting portion 420 and a second connecting portion 520, as well as a first pad portion 410 and a second pad portion 510 spaced apart from each other on the sixth surface 106 of the body 100. Specifically, the first external electrode 400 includes a first pad portion 410 formed on the sixth surface 106 of the body 100 and a first connecting portion 420 penetrating at least a portion of the body 100 to contact and connect to the coil portion 300 and the first pad portion 410. The second external electrode 500 includes a second pad portion 510 formed on the sixth surface 106 of the body 100 and a second connecting portion 520 penetrating at least a portion of the body 100 to contact and connect to the coil portion 300 and the second pad portion 510.

[0083] The first pad portion 410 and the second pad portion 510 can be formed in a single layer or multiple layers. As an example, the first pad portion 410 can be formed having a first layer containing Cu, a second layer disposed on the first layer and containing Ni, and a third layer disposed on the second layer and containing Sn.

[0084] The first connecting portion 420 and the second connecting portion 520 penetrate at least a portion of the main body 100. That is, in this exemplary embodiment, the first pad portion 410 and the second pad portion 510 are connected to the first lead pattern 331 and the second lead pattern 332 through the first connecting portion 420 and the second connecting portion 520 disposed inside the main body; the first external electrode 400 and the second external electrode 500 are not connected to the first lead pattern 331 and the second lead pattern 332 through the surface of the main body 100.

[0085] The first connection portion 420 and the second connection portion 520 may extend from the coil portion 300. As an example, after forming a resist with openings on the first lead pattern 331 and the second lead pattern 332, the first connection portion 420 and the second connection portion 520 may be grown by plating through the openings of the resist. Alternatively, the first connection portion 420 and the second connection portion 520 may be formed by forming a body 100 and forming vias on a sixth surface of the body 100, subsequently filling the vias with a conductive material. In the former case, when forming the first connection portion 420 and the second connection portion 620 by electroplating, the first lead pattern 331 and the second lead pattern 332 may serve as a feed layer. As a result, a seed layer (e.g., no electroplating layer) may not exist at the boundary between the first connection portion 420 and the second connection portion 520 and the coil portion 300, but this is not a limitation. In the latter case, the first connection portion 420 and the second connection portion 520 may include a seed layer formed inside the via, but this is not a limitation.

[0086] in addition, Figure 7 , Figure 8 and Figure 10 It is shown that each of the first connecting portion 420 and the second connecting portion 520 is uniformly formed into a cylindrical shape; however, this is merely for the purpose of illustration and description. As another non-limiting example, the first connecting portion 420 may be formed in multiple forms and in the shape of a rectangular column.

[0087] Figure 11 This is a schematic diagram illustrating a magnetic composite sheet according to an exemplary embodiment, and Figure 12 yes Figure 11 An enlarged view of the "C".

[0088] based on Figure 11 and Figure 12 According to an exemplary embodiment, the magnetic composite sheet 3000 includes a first magnetic metal powder particle 11, a second magnetic metal powder particle 12, a third magnetic metal powder particle 13, and an insulating resin R.

[0089] The first magnetic metal powder particles 11 to the third magnetic metal powder particles 13 are described in the coil assembly 1000 according to one of the exemplary embodiments above, and their description will be omitted.

[0090] Furthermore, contrary to the description in the coil assembly 1000 of one of the preceding exemplary embodiments, the insulating resin R of the magnetic composite sheet 3000 according to this exemplary embodiment is uncured or semi-cured. That is, the insulating resin R of this disclosure is uncured or semi-cured in the magnetic composite sheet 3000 as in this exemplary embodiment, and becomes cured in the body 100 formed by stacking such magnetic composite sheets 3000 on an insulating substrate 200 and curing it.

[0091] Additionally, although not shown, the magnetic composite sheet 3000 according to this exemplary embodiment may include: a functional layer including first magnetic metal powder particles 11 to third magnetic metal powder particles 13 and insulating resin R; a support film disposed on one surface of the functional layer; and a protective film disposed on the other surface of the functional layer. In the case of the magnetic composite sheet 3000, removing the protective film causes the functional layer to face the insulating substrate 200 and be stacked thereon. The stacked support film can then be removed.

[0092] As described above, according to this disclosure, leakage current in coil assemblies comprising three or more types of magnetic metal powder particles with different diameters can be reduced.

[0093] Although exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and alterations may be made without departing from the scope of this disclosure as defined by the appended claims.

Claims

1. A coil assembly, comprising: The main body and the coil portion, wherein the coil portion is embedded in the main body. The main body includes: The first magnetic particle comprises a core and an oxide film, the core comprising a compound represented by Formula 1 below, and the oxide film comprising at least one of silicon (Si) or chromium (Cr) and deposited directly on the surface of the core; The second magnetic particle has a diameter larger than that of the first magnetic particle; and The third magnetic particle has a larger diameter than the second magnetic particle. Fe a Si b Cr c [Formula 1] Where 3 at% ≤ b ≤ 6 at%, 2.65 at% ≤ c ≤ 3.65 at%, and a + b + C = 100, Each of the second magnetic particle and the third magnetic particle comprises a metal particle and an insulating coating, wherein the insulating coating is directly disposed on the surface of the second metal particle and the third metal particle, and wherein the insulating coating comprises an insulating resin.

2. The coil assembly according to claim 1, wherein, The diameter of the first magnetic particle is less than 1 μm.

3. The coil assembly according to claim 1, wherein, The diameter of the first magnetic particle is 0.1 μm to 0.2 μm.

4. The coil assembly according to claim 1, wherein, The diameter of the second magnetic particle is 1 μm to 2 μm, and The diameter of the third magnetic particle is 25 μm to 30 μm.

5. The coil assembly according to claim 1, wherein, The thickness of the coil assembly is 0.85 mm or less.

6. The coil assembly according to claim 1, wherein, Each of the metal particles of the second magnetic particle and the metal particles of the third magnetic particle comprises an iron (Fe)-silicon (Si)-boron (B)-copper (Cu) based alloy powder.

7. The coil assembly of claim 1, further comprising a first external electrode and a second external electrode, the first external electrode and the second external electrode being spaced apart on the outer surface of the body and connected to two ends of the coil portion exposed on the outer surface of the body.

8. The coil assembly according to claim 1, wherein, The coil assembly also includes an insulating substrate, which is embedded in the main body. The coil portion includes a first coil pattern and a second coil pattern, which are respectively disposed on one surface and the other surface of the insulating substrate facing each other.

9. The coil assembly according to claim 8, wherein, Each of the first coil pattern and the second coil pattern includes a first conductive layer formed on the insulating substrate and a second conductive layer formed on the first conductive layer.

10. The coil assembly according to claim 9, wherein, Each of the first conductive layer and the second conductive layer comprises copper (Cu). Furthermore, the copper density of the first conductive layer is lower than that of the second conductive layer.

11. The coil assembly according to claim 9, wherein, The side surface of the first conductive layer is exposed through the second conductive layer.

12. The coil assembly according to claim 9, wherein, The second conductive layer covers the side surface of the first conductive layer and contacts the insulating substrate.

13. A magnetic composite sheet, comprising: The first magnetic particle includes a core and an oxide film, the core comprising a compound represented by Formula 1 below, and the oxide film comprising at least one of silicon (Si) or chromium (Cr) and formed directly on the surface of the core. The second magnetic particle has a diameter larger than that of the first magnetic particle. The third magnetic particle has a diameter larger than that of the second magnetic particle; and Insulating resin: Fe a Si b Cr c [Formula 1] Where 3 at% ≤ b ≤ 6 at%, 2.65 at% ≤ c ≤ 3.65 at%, and a + b + C = 100, Each of the second magnetic particle and the third magnetic particle comprises a metal particle and an insulating coating, wherein the insulating coating is directly disposed on the surface of the second metal particle and the third metal particle, and wherein the insulating coating comprises an insulating resin.

14. The magnetic composite sheet according to claim 13, wherein, The diameter of the first magnetic particle is 0.1 μm to 0.2 μm.

15. The magnetic composite sheet according to claim 13, wherein: The diameter of the second magnetic particle is 1 μm to 2 μm, and The diameter of the third magnetic particle is 25 μm to 30 μm.

16. The coil assembly according to claim 1, wherein, The insulating resin includes epoxy resin.

17. The coil assembly according to claim 1, wherein, The insulating resin includes polyamide resin.

18. The coil assembly according to claim 1, wherein, The thickness of the insulating coating on the second magnetic particle and the third magnetic particle is greater than 0.01 μm and less than 1 μm.

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