Coil component

Abstract

The invention provides a coil assembly. The coil component includes a body having a first surface, a second surface opposite the first surface in a first direction, and a plurality of side surfaces connecting the first surface to the second surface. A coil is disposed in the body, and first and second external electrodes each including a first metal layer electrically connected to the coil and disposed on a side surface of the body are disposed. A first insulating layer is disposed on the side surface of the body covering at least a portion of the first metal layer. A surface roughness Ry is formed on at least a portion of a surface of the first metal layer in contact with the first insulating layer, where the surface roughness Ry is defined as a maximum height roughness having an average value of 1 [mu] m or more, enhancing adhesion between the first metal layer and the first insulating layer.

Description

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0112111, filed on August 21, 2024, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure relates to a coil assembly. Background Technology

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

[0004] As electronic devices have been designed to be high-performance and have reduced size, the number of electronic components used in electronic devices has increased, while electronic devices have been designed to have reduced size.

[0005] The outer electrodes of a coil assembly are typically formed on two side surfaces of the body that are opposite each other along the length direction. In this case, an effective area loss of magnetic material may occur due to the thickness of the outer electrodes and the insulating layer covering them. The thickness of the outer electrodes can be reduced by adjusting the plating thickness, but the DC resistance (Rdc) may increase, potentially limiting its application. Therefore, the importance of methods for reducing the thickness of the insulating layer covering the outer electrodes has become apparent. Summary of the Invention

[0006] One aspect of this disclosure is to provide a coil assembly in which the surface insulating layer may have a reduced thickness, thereby increasing the capacitance.

[0007] One aspect of this disclosure is to provide a coil assembly in which defects in the coating surface insulation layer can be resolved.

[0008] According to one aspect of this disclosure, a coil assembly includes: a body including a first surface, a second surface opposite to the first surface in a first direction, and a plurality of side surfaces connecting the first surface to the second surface; a coil disposed in the body; a first external electrode and a second external electrode including a first metal layer connected to the coil and disposed on the side surface of the body; and a first insulating layer disposed on the side surface of the body and covering at least a portion of the first metal layer, wherein a surface roughness Ry is formed on at least a portion of the surface of the first metal layer in contact with the first insulating layer, and wherein the surface roughness Ry has an average value of 1 μm or greater.

[0009] According to one aspect of this disclosure, a coil assembly includes: a body including a first surface, a second surface opposite to the first surface in a first direction, a plurality of side surfaces connecting the first surface to the second surface, and a stepped portion located at an edge formed by the second surface and the plurality of side surfaces; a coil disposed in the body; a first external electrode and a second external electrode including a first metal layer connected to the coil and disposed on the side surface of the body; and a first insulating layer disposed on the side surface of the body and the stepped portion and covering at least a portion of the first metal layer, wherein a surface roughness Ry is formed on at least a portion of the surface of the first metal layer that contacts the first insulating layer. Attached Figure Description

[0010] The above and other aspects, features and advantages of this disclosure will become more clearly understood from the following detailed embodiments, taken in conjunction with the accompanying drawings, in which: Figure 1 This is a perspective view showing a coil assembly according to a first embodiment of the present disclosure; Figure 2 It is shown Figure 1 A diagram of the coil in the diagram; Figure 3 This shows the view observed in direction A. Figure 1 A diagram of the coil assembly in the diagram; Figure 4 It is along Figure 1 A cross-sectional view of the coil assembly taken by line I-I' in the diagram; Figure 5 It is shown Figure 4 An enlarged view of part B in the image; Figure 6 It is along Figure 1 A cross-sectional view of the coil assembly taken from line II-II' in the diagram; Figure 7 This is a diagram illustrating a coil assembly according to a second embodiment of the present disclosure; Figure 8 It is shown Figure 7 A diagram of the insulating layer in the diagram; and Figure 9 It is along Figure 7 The cross-sectional view of the coil assembly taken from line III-III' in the diagram. Detailed Implementation

[0011] In the following description, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0012] However, this disclosure can be exemplified in many different forms and should not be construed as limiting oneself to the specific embodiments set forth herein. Unless there is a clearly different meaning in the context, expressions used in the singular include plural expressions. The terms “comprising,” “including,” “configured as,” etc., in the specification are used to mean the presence of features, quantities, steps, operations, elements, parts, or combinations thereof, and do not preclude the possibility of combining or adding one or more features, quantities, steps, operations, elements, parts, or combinations thereof. Furthermore, the expression “an element is positioned on” can mean that an element can be positioned above or below a target portion, and does not necessarily mean that the element is positioned above the target portion in the direction of gravity.

[0013] It should be understood that when an element is "combined" with / "attached to" another element or "connected" to another element, the element may be directly combined with / attached to / connected to the other element, and there may be intermediate elements between the element and the other element. Conversely, it should be understood that when an element is "directly combined" with / attached to / connected to another element or "directly connected" to another element, there are no intermediate elements between the element and the other element.

[0014] For example, without departing from the spirit and scope of this disclosure, the structures, shapes, and dimensions described as examples in the embodiments of this disclosure may be implemented in another exemplary embodiment.

[0015] In the accompanying drawings, the X direction can be defined as a first direction or the thickness direction, the Y direction can be defined as a second direction or the length direction, and the Z direction can be defined as a third direction or the width direction.

[0016] In the accompanying drawings, the same elements will be represented by the same reference numerals. Furthermore, redundant and detailed descriptions of known functions and elements that may unnecessarily obscure the gist of this disclosure will not be provided.

[0017] Various types of electronic components are used in electronic devices, and various types of coil assemblies can be appropriately used among these electronic components for the purpose of noise reduction.

[0018] In other words, in electronic devices, coil assemblies can be used as power inductors, high-frequency (HF) inductors, general-purpose ferrite beads, high-frequency ferrite beads (e.g., ferrite beads suitable for the GHz band), common-mode filters, etc.

[0019] (First embodiment) Figure 1 This is a perspective view showing a coil assembly according to the first embodiment. Figure 2 It is shown Figure 1 A diagram of the coil in the diagram. Figure 3This shows the view observed in direction A. Figure 1 A diagram of the coil assembly. Figure 4 It is along Figure 1 The cross-sectional view of the coil assembly taken by line I-I' in the diagram. Figure 5 It is shown Figure 4 An enlarged view of part B in the image. Figure 6 It is along Figure 1 The cross-sectional view of the coil assembly taken from line II-II' in the diagram.

[0020] Reference Figures 1 to 6 According to an embodiment, the coil assembly 1000 includes a body 100, a support member 200, a coil 300, external electrodes 400 and 500, a first insulating layer 610 and a second insulating layer 620, and may also include an insulating film IF.

[0021] The main body 100 can form the overall appearance of the coil assembly 1000 in the embodiment, and the support member 200 and the coil 300 can be embedded therein.

[0022] The main body 100 may have a hexahedral shape.

[0023] In the following description, the embodiments may be described assuming that the body 100 has a hexahedral shape. However, this description does not exclude, from the scope of the embodiments, coil assemblies comprising bodies formed in shapes other than hexahedral.

[0024] The body 100 may include a first surface 101 and a second surface 102 opposite to each other in a first direction (X direction), a third surface 103 and a fourth surface 104 opposite to each other in a second direction (Y direction), and a fifth surface 105 and a sixth surface 106 opposite to each other in a third direction (Z direction). The third surface 103, the fourth surface 104, the fifth surface 105, and the sixth surface 106 may be side surfaces connecting the first surface 101 to the second surface 102. When the coil assembly 1000 according to the embodiment is mounted on a printed circuit board or other mounting substrate, the first surface 101 of the body 100 may face the mounting surface of the printed circuit board or other mounting substrate and may be mounted on the printed circuit board or other mounting substrate.

[0025] For example, as described below, according to an embodiment, the coil assembly 1000 may have a length of 2.0 mm, a width of 1.2 mm, and a thickness of 0.65 mm. The coil assembly 1000 may include a body 100, external electrodes 400 and 500, and insulating layers 610 and 620, but its embodiments are not limited thereto. The dimensions of the length, width, and thickness of the coil assembly described above can exclude process errors (or tolerances), and the actual length, width, and thickness of the coil assembly due to tolerances may differ from the dimensions described above, and the range identified as tolerance may be included in the embodiments.

[0026] Based on an image of a third-direction (Z-direction) central portion of the coil assembly 1000, obtained by optical microscopy or scanning electron microscopy (SEM), the length of the coil assembly 1000 can refer to the maximum value of the dimensions of multiple line segments of the coil assembly 1000 connected to the two outermost boundary lines of the coil assembly 1000 that are opposite each other in the second direction (Y-direction) and parallel to the second direction (Y-direction) shown in the cross-sectional image. Alternatively, the length of the coil assembly 1000 can refer to the arithmetic mean of at least three dimensions of the coil assembly 1000 connected to the two outermost boundary lines of the coil assembly 1000 that are opposite each other in the second direction (Y-direction) and parallel to the second direction (Y-direction) shown in the cross-sectional image.

[0027] Based on an image of a second-direction (Y-direction) - first-direction (X-direction) cross-section of the central portion of the coil assembly 1000 in a third-direction (Z-direction) region obtained by optical microscopy or scanning electron microscopy (SEM), the thickness of the coil assembly 1000 may refer to the maximum value of the dimensions of multiple line segments of the coil assembly 1000 that are opposite each other in the first direction (X-direction) and parallel to the first direction (X-direction) as shown in the cross-sectional image. Alternatively, the thickness of the coil assembly 1000 may refer to the arithmetic mean of at least three dimensions of the coil assembly 1000 that are opposite each other in the first direction (X-direction) and parallel to the first direction (X-direction) as shown in the cross-sectional image.

[0028] Based on an image of a third-direction (Z-direction) - first-direction (X-direction) cross-section of the central portion of the coil assembly 1000 in the second direction (Y-direction) obtained by optical microscopy or scanning electron microscopy (SEM), the width of the coil assembly 1000 may refer to the maximum value of the dimensions of multiple line segments of the coil assembly 1000 that are opposite each other in the third-direction (Z-direction) and parallel to the third-direction (Z-direction) shown in the cross-sectional image. Alternatively, the width of the coil assembly 1000 may refer to the arithmetic mean of at least three dimensions of the coil assembly 1000 that are opposite each other in the third-direction (Z-direction) and parallel to the third-direction (Z-direction) shown in the cross-sectional image.

[0029] Optionally, the length, width, and thickness of the coil assembly 1000 can be measured using a micrometer. The micrometer measurement method can be performed by zeroing a micrometer used for metrological R&R (repeatability and reproducibility) testing, inserting the coil assembly 1000 according to the embodiment between the tips of the micrometer, and rotating the measuring rod of the micrometer. In measuring the length of the coil assembly 1000 using the micrometer method, the length of the coil assembly 1000 can refer to a single measurement or the arithmetic mean of multiple measurements, which can be equally applied to the measurement of the width and thickness of the coil assembly 1000.

[0030] The body 100 may include magnetic metal powder and insulating resin. Specifically, the body 100 may be formed by laminating one or more magnetic composite sheets comprising insulating resin and magnetic metal powder dispersed in the insulating resin, and then curing the magnetic composite sheets. However, the body 100 may have structures other than those in which the magnetic metal powder is dispersed in the insulating resin. For example, the body 100 may be formed of a magnetic material such as ferrite.

[0031] The magnetic material included in the main body 100 may be ferrite or magnetic metal powder.

[0032] The ferrite powder can be at least one of the following: spinel-type ferrites (such as Mg-Zn-based ferrites, Mn-Zn-based ferrites, Mn-Mg-based ferrites, Cu-Zn-based ferrites, Mg-Mn-Sr-based ferrites, Ni-Zn-based ferrites), hexagonal ferrites (such as Ba-Zn-based ferrites, Ba-Mg-based ferrites, Ba-Ni-based ferrites, Ba-Co-based ferrites, Ba-Ni-Co-based ferrites), garnet-type ferrites (such as Y-based ferrites), and Li-based ferrites.

[0033] Magnetic metal powders may include one or more selected from the group consisting of iron (Fe), silicon (Si), chromium (Cr), cobalt (Co), molybdenum (Mo), aluminum (Al), niobium (Nb), copper (Cu), and nickel (Ni). For example, magnetic metal powders may be at least one selected from pure iron powder, Fe-Si based alloy powder, Fe-Si-Al based alloy powder, Fe-Ni based alloy powder, Fe-Ni-Mo based alloy powder, Fe-Ni-Mo-Cu based alloy powder, Fe-Co based alloy powder, Fe-Ni-Co based alloy powder, Fe-Cr based alloy powder, Fe-Cr-Si based alloy powder, Fe-Si-Cu-Nb based alloy powder, Fe-Ni-Cr based alloy powder, and Fe-Cr-Al based alloy powder.

[0034] Magnetic metal powders can be amorphous or crystalline. For example, magnetic metal powders can be Fe-Si-B-Cr amorphous alloy powders, but embodiments thereof are not limited to this.

[0035] The particles of ferrite and magnetic metal powders may have an average diameter of about 0.1 μm to 30 μm, but the embodiments are not limited thereto. The average diameter of the magnetic metal powder may refer to a particle size expressed as D50 or D90.

[0036] The body 100 may include two or more types of magnetic metal powder dispersed in a resin. Here, different types of magnetic metal powder may refer to magnetic metal powders dispersed in a resin that can be distinguished from each other by at least one of average diameter, composition, crystallinity, and shape.

[0037] The insulating resin may include epoxy resin, polyimide, liquid crystal polymer, etc., either alone or in combination, but its embodiments are not limited thereto.

[0038] The main body 100 may include a core 110 that penetrates the central portion of the support member 200 and the coil 300, as will be described later. The core 110 may be formed by filling a through-hole through which the magnetic composite sheet passes through the central portion of the coil 300 and the support member 200, but embodiments thereof are not limited thereto.

[0039] The support member 200 may be disposed in the main body 100 and may support the coil 300, which will be described later.

[0040] The support member 200 may be formed of an insulating material including a thermosetting insulating resin such as epoxy resin, a thermoplastic insulating resin such as polyimide, or a photosensitive insulating resin, or may be formed of an insulating material in which a reinforcing material such as glass fiber or inorganic filler is impregnated in the insulating resin. For example, the support member 200 may be formed of an insulating material such as copper-clad laminate (CCL), prepreg, Ajinomoto build-up film (ABF), FR-4, bismaleimide triazine (BT) film, photosensitive dielectric (PID) film, etc., but its embodiments are not limited thereto.

[0041] As an inorganic filler, one or more of the following can be used: silicon dioxide (SiO2), aluminum oxide (Al2O3), silicon carbide (SiC), barium sulfate (BaSO4), talc, clay, 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).

[0042] When the support member 200 is formed of an insulating material including reinforcing material, the support member 200 provides better rigidity. When the support member 200 is formed of an insulating material excluding glass fiber, the support member 200 can help reduce the overall thickness of the coil 300. When the support member 200 is formed of an insulating material including photosensitive insulating resin, the number of processes used to form the coil 300 is reduced, which can help reduce production costs and allow for the formation of fine vias.

[0043] The coil 300 can be disposed in the main body 100 and can exhibit the characteristics of a coil assembly. For example, when the coil assembly 1000 in the embodiment is used as a power inductor, the coil 300 can store an electric field as a magnetic field and can maintain the output voltage, thereby stabilizing the power of the electronic device.

[0044] A coil 300 may be formed on at least one of two opposing surfaces of the support member 200, and may form at least one turn. The coil 300 may be disposed on one and another opposing surfaces of the support member 200 in the thickness direction of the body 100. In an embodiment, the coil 300 may include a first coil pattern 311 and a first lead-out pattern 331 disposed on one surface of the support member 200 opposite to the first surface 101 of the body 100, a second coil pattern 312 and a second lead-out pattern 332 disposed on the other surface of the support member 200, and a through-hole 321 penetrating the support member 200 and connecting the inner ends of the first coil pattern 311 and the second coil pattern 312 to each other. Therefore, the coil 300 according to the embodiment can be used as a coil.

[0045] Each of the first coil pattern 311 and the second coil pattern 312 can be formed as a planar spiral with at least one turn about the core 110 of the body 100 as the axis. For example, relative to Figure 1 , Figure 2 and Figure 4 In the direction of the core, the first coil pattern 311 can be formed on the lower surface of the support member 200 with the core 110 as the axis, with at least one turn. The second coil pattern 312 can be formed on the upper surface of the support member 200 with the core 110 as the axis, with at least one turn.

[0046] Lead-out patterns 331 and 332 can be connected to coil patterns 311 and 312, respectively, and can be exposed on the third surface 103 and the fourth surface 104 of the body 100, respectively. Specifically, the first lead-out pattern 331 can be disposed on one surface of the support member 200, can be connected to the first coil pattern 311, and can be exposed on the third surface 103 of the body 100. The second lead-out pattern 332 can be disposed on the other surface of the support member 200, can be connected to the second coil pattern 312, and can be exposed on the fourth surface 104 of the body 100. Lead-out patterns 331 and 332 can be exposed on the third surface 103 and the fourth surface 104 of the body 100, and can contact and be connected to the first metal layers 410 and 510 of the external electrodes 400 and 500, which will be described later.

[0047] At least one of the coil patterns 311 and 312, the via 321, and the lead-out patterns 331 and 332 may include at least one conductive layer.

[0048] For example, when the second coil pattern 312, via 321, and second lead-out pattern 332 are formed by plating, each of the second coil pattern 312, via 321, and second lead-out pattern 332 may include a seed layer formed by vapor deposition such as electroless plating or sputtering, and an electroplated layer. Here, the electroplated layer may have a single-layer structure or a multi-layer structure. The multi-layer electroplated layer may be formed as a conformal film structure in which one electroplated layer is covered by another electroplated layer, or it may be formed as a shape in which another electroplated layer is laminated only on one surface of an electroplated layer. The seed layers of the second coil pattern 312, via 321, and second lead-out pattern 332 may be integrated such that no boundary is formed between them, but embodiments thereof are not limited thereto. The electroplated layers of the second coil pattern 312, via 321, and second lead-out pattern 332 may be integrated and may not form a boundary therebetween, but embodiments thereof are not limited thereto.

[0049] As another example, when the first coil pattern 311 and the first lead pattern 331, as well as the second coil pattern 312 and the second lead pattern 332, are formed separately and then laminated together on the support member 200 to form the coil 300, the via 321 may include a high-melting-point metal layer and a low-melting-point metal layer with a melting point lower than that of the high-melting-point metal layer. Here, the low-melting-point metal layer may be formed of solder comprising lead (Pb) and / or tin (Sn). At least a portion of the low-melting-point metal layer may melt due to the pressure and temperature during lamination, such that an intermetallic compound layer (IMC layer) may be formed at the boundary between the low-melting-point metal layer and the second coil pattern 312.

[0050] For example, such as Figure 4 and Figure 6As shown, the first coil pattern 311 and the first lead-out pattern 331, as well as the second coil pattern 312 and the second lead-out pattern 332, may protrude from the lower and upper surfaces of the support member 200, respectively. As another example, the first coil pattern 311 and the first lead-out pattern 331 may be embedded in the lower surface of the support member 200, such that the lower surfaces of the first coil pattern 311 and the first lead-out pattern 331 are exposed on the lower surface of the support member 200, and the second coil pattern 312 and the second lead-out pattern 332 may protrude from the upper surface of the support member 200. In this case, a recess may be formed on the lower surface of each of the first coil pattern 311 and the first lead-out pattern 331, such that the lower surface of the support member 200 and the lower surfaces of the first coil pattern 311 and the first lead-out pattern 331 may not be on the same plane. As another example, the first coil pattern 311 and the first lead-out pattern 331 may protrude from the lower surface of the support member 200, and the second coil pattern 312 and the second lead-out pattern 332 may be embedded in the upper surface of the support member 200, such that the upper surfaces of the second coil pattern 312 and the second lead-out pattern 332 are exposed to the upper surface of the support member 200. In this case, a recess may be formed on the upper surface of each of the second coil pattern 312 and the second lead-out pattern 332, such that the upper surface of the support member 200 and the upper surfaces of the second coil pattern 312 and the second lead-out pattern 332 may not be on the same plane. As another example, the first coil pattern 311 and the first lead-out pattern 331 may be embedded in the lower surface of the support member 200, such that the lower surfaces of the first coil pattern 311 and the first lead-out pattern 331 are exposed to the lower surface of the support member 200, and the second coil pattern 312 and the second lead-out pattern 332 may be embedded in the upper surface of the support member 200, such that the upper surfaces of the second coil pattern 312 and the second lead-out pattern 332 are exposed to the upper surface of the support member 200.

[0051] Each of the coil patterns 311 and 312, the via 321, and the lead-out patterns 331 and 332 may be formed of a conductive material such as copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), molybdenum (Mo), or alloys thereof, but embodiments thereof are not limited thereto.

[0052] An insulating film IF may be formed along the surfaces of the support member 200 and the coil 300. The insulating film IF protects the coil 300 and insulates the coil 300 from the body 100, which includes magnetic material, and may include commonly used insulating materials such as parylene. The insulating material included in the insulating film IF can be any material and is not particularly limited. The insulating film IF may be formed by methods such as vapor deposition, but embodiments are not limited thereto, and the insulating film may also be formed by laminating the insulating film to both surfaces of the support member 200.

[0053] External electrodes 400 and 500 may be disposed on the side surface of the body 100 and may include first metal layers 410 and 510 connected to the coil 300. (See reference...) Figure 4 The first metal layer 410 of the first external electrode can be disposed on the third surface 103 of the body 100 and can be connected to the first lead-out pattern 331, and the first metal layer 510 of the second external electrode can be disposed on the fourth surface 104 of the body 100 and can be connected to the second lead-out pattern 332.

[0054] External electrodes 400 and 500 may extend to the first surface of the body 100. That is, the first metal layers 410 and 510 may include connection portions 411 and 511 disposed on the side surface of the body and pad portions 412 and 512 extending to the first surface of the body 100.

[0055] Connecting portions 411 and 511 can be disposed on the side surface of the main body and can be directly connected to the coil 300. That is, connecting portions 411 and 511 of the first metal layers 410 and 510 can be connected to the first lead-out pattern 331 and the second lead-out pattern 332.

[0056] Pad portions 412 and 512 may extend from connection portions 411 and 511 to the first surface of the body 100. Specifically, the first metal layer 410 of the first external electrode may include a first connection portion 411 disposed on the third surface 103 of the body and a first pad portion 412 extending to the first surface of the body 100. Similarly, the first metal layer 510 of the second external electrode may include a second connection portion 511 disposed on the fourth surface 104 of the body and a second pad portion 512 extending to the first surface of the body 100.

[0057] The first external electrode 400 and the second external electrode 500 may be spaced apart from each other on the first surface of the body 100. That is, the first pad portion 412 and the second pad portion 512 may be spaced apart from each other on the first surface of the body 100.

[0058] The first metal layers 410 and 510 of the external electrodes 400 and 500 can be formed on the surface of the body 100 by forming a resist layer on the surface of the body 100 and performing electroplating. When the body 100 includes magnetic metal powder, the magnetic metal powder can be exposed on the surface of the body 100. The magnetic metal powder exposed on the surface of the body 100 can provide conductivity to the surface of the body 100 during electroplating, and the first metal layers 410 and 510 can be formed on the surface of the body 100 by electroplating.

[0059] The connecting portions 411 and 511 of the first metal layers 410 and 510, as well as the pad portions 412 and 512, can be formed using the same plating process, so that no boundary is formed between them. That is, the first connecting portion 411 and the first pad portion 412 can be integrated with each other, and the second connecting portion 511 and the second pad portion 512 can be integrated with each other. Furthermore, the connecting portions 411 and 511 and the pad portions 412 and 512 can be formed of the same metal. However, this disclosure does not exclude examples where the connecting portions 411 and 511 and the pad portions 412 and 512 can be formed using different plating processes and where a boundary is formed therebetween. The first metal layers 410 and 510 can be formed of conductive materials such as copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), or alloys thereof, but embodiments thereof are not limited thereto. As an example, although not limited thereto, the first metal layers 410 and 510 can be copper (Cu) plating.

[0060] The first metal layers 410 and 510 may have a thickness of 0.3 μm to 10 μm. When the thickness of the first metal layers 410 and 510 is less than 0.3 μm, the external electrodes 400 and 500 may detach and peel off during substrate mounting, potentially degrading the connection reliability between the coil 300 and the external electrodes 400 and 500. When the thickness of the first metal layers 410 and 510 exceeds 10 μm, it may be difficult to reduce the thickness of the coil assembly, and process efficiency may degrade.

[0061] Reference Figure 5 The first metal layers 410 and 510 may be covered by the first insulating layer 610, as will be described later. That is, the first metal layers 410 and 510 may be in direct contact with the first insulating layer 610 on the side surfaces 103 and 104 of the body. In this case, surface roughness may be formed on at least a portion of the surfaces of the first metal layers 410 and 510 that are in contact with the first insulating layer 610. Specifically, surface roughness may be formed on at least a portion of the first connecting portion 411 and the second connecting portion 511.

[0062] Because surface roughness is formed on the boundary surfaces of the first metal layers 410 and 510 that contact the first insulating layer 610, the thickness of the first insulating layer 610 can be reduced uniformly. Furthermore, the bonding strength between the first metal layers 410 and 510 and the first insulating layer 610 can be improved.

[0063] The first insulating layer 610 can be formed using the transfer paste described below, and the amount of paste transferred may need to be increased to ensure the flatness of the insulating layer. However, correspondingly, the thickness of the first insulating layer 610 may increase, which may be disadvantageous in terms of effective magnetic area.

[0064] According to the embodiment, a surface roughness can be formed on the surface of the first metal layers 410 and 510 on which the first insulating layer 610 is disposed. In the case of metals with high surface energy, the flowability of the material coated on the metal can be improved as the surface roughness increases. When a surface roughness is formed on the first metal layers 410 and 510, the flowability can be improved when forming the first insulating layer 610, and the thickness of the insulating layer can be reduced and made more uniform even when the amount of paste transferred is reduced.

[0065] Specifically, the surface roughness Ry of the first metal layers 410 and 510 may have an average value of 1 μm or greater. When the surface roughness is less than 1 μm, flatness may not be sufficiently improved, and defects such as exposed external electrodes and pinhole defects may occur.

[0066] The surface roughness Ry of the first metal layers 410 and 510 can have an average value of 10 μm or less. When the surface roughness of the first metal layers 410 and 510 exceeds 10 μm, the excessive roughness may cause the paste to be partially untransferred, which is an adverse effect. In other words, an exposure defect may occur, resulting in a portion of the external electrode being exposed.

[0067] Table 1 below lists the results of the characteristic evaluation based on the surface roughness Ry values ​​formed on the first metal layers 410 and 510. Exposure defects, pinhole defects, and flatness of the external electrode were measured when the same amount of paste was transferred.

[0068] [Table 1]

[0069] Referring to [Table 1], when the surface roughness Ry is less than 1 μm, the flatness may not be sufficiently improved, and exposure defects and / or pinhole defects of the external electrode may occur. That is, in order to improve the exposure defects and pinhole defects of the external electrode, it may be necessary to increase the paste transfer amount, and therefore, the thickness of the first insulating layer 610 may be increased.

[0070] When the surface roughness Ry exceeds 10 μm, the opposite effect may occur, resulting in partial untransfer of the paste due to excessive roughness. In other words, exposure defects may occur, such as partial exposure of the external electrode.

[0071] According to the embodiment, surface roughness may refer to maximum height roughness Ry. Maximum height roughness Ry may be a value measured from the distance between the highest peak and the lowest valley of the virtual midline of the surface roughness curve.

[0072] The method for measuring surface roughness is as follows. First, a first-direction-second-direction cross-sectional sample can be obtained by grinding the coil assembly to a depth of 1 / 2 in the third direction (Z direction). In the obtained cross-section, the distance between the highest peak and the lowest valley line can be measured along a reference length of 10 μm along the first metal layers 410 and 510. (Refer to...) Figure 5 The maximum height roughness Ry can be calculated by adding the distance Rp from the centerline m to the highest peak line to the distance Rv from the centerline m to the lowest valley line. The number of samples can be 20, and the maximum height roughness Ry measured once for each sample can be an arithmetic mean, which can be the surface roughness according to the embodiment, but the embodiment is not limited thereto.

[0073] The method for setting surface roughness on the connecting portions 411 and 511 is not limited to any particular example. For example, to set surface roughness on the connecting portions 411 and 511, plasma surface treatment can be performed, or a chemical treatment method such as anisotropic etching can be used. In addition, surface roughness on the connecting portions 411 and 511 can be set by forming an oxide, or by changing the plating process conditions and performing rough plating.

[0074] Surface roughness may not be formed on the surfaces of the first metal layers 410 and 510 that do not contact the first insulating layer 610. Specifically, surface roughness may not be formed on the first pad portion 412 and the second pad portion 512, or a surface roughness smaller than that formed on the first connecting portion 411 and the second connecting portion 511 may be formed. As described below, the second metal layers 420 and 520 may be provided on the first pad portion 412 and the second pad portion 512.

[0075] External electrodes 400 and 500 may further include second metal layers 420 and 520 disposed on a first surface of the body 100. The second metal layers 420 and 520 may be disposed on pad portions 412 and 512 of the first metal layers 410 and 510. Specifically, the second metal layer 420 of the first external electrode 400 may be disposed on the first pad portion 412, and the second metal layer 520 of the second external electrode 500 may be disposed on the second pad portion 512. The second metal layers 420 and 520 may be platings grown on the pad portions 412 and 512 exposed outwards through the first insulating layer 610 and the second insulating layer 620, as will be described later. For example, each of the second metal layers 420 and 520 may include a nickel (Ni) plating disposed on the pad portions 412 and 512, and a tin (Sn) plating disposed on the nickel (Ni) plating, but embodiments are not limited thereto.

[0076] The second metal layers 420 and 520 can be formed with a thickness ranging from 0.3 μm to 10 μm. When the thickness of the second metal layers 420 and 520 is less than 0.3 μm, the second metal layers 420 and 520 may detach and peel off during substrate mounting, and the connection reliability between the coil 300 and the external electrodes 400 and 500 may deteriorate. When the thickness of the second metal layers 420 and 520 exceeds 10 μm, it may be difficult to reduce the thickness of the coil assembly, and the process efficiency may deteriorate.

[0077] The first insulating layer 610 may be disposed on the side surface of the main body and may cover at least a portion of the first metal layers 410 and 510. Specifically, the first insulating layer 610 may be disposed on the third surface 103 and the fourth surface 104 of the main body and may cover the first connecting portion 411 of the first metal layer 410 and the second connecting portion 511 of the first metal layer 510.

[0078] The first insulating layer 610, together with the second insulating layer 620 described later, may cover the connection portions 411 and 511 of the first metal layers 410 and 510, and may expose at least a portion of the pad portions 412 and 512 of the first metal layers 410 and 510. That is, the first insulating layer 610 may not contact at least a portion of the pad portions 412 and 512.

[0079] When the second metal layers 420 and 520 are formed by plating, the first insulating layer 610 can be used as a plating resist layer. Therefore, after the first metal layers 410 and 510 of the external electrodes 400 and 500 are formed, the first insulating layer 610 can be formed on the body 100 in a manner that covers the connection portions 411 and 511 and exposes the pad portions 412 and 512, thereby defining, together with the second insulating layer 620, the area in which the second metal layers 420 and 520 are formed. However, this embodiment is not limited to this.

[0080] The first insulating layer 610 may include thermoplastic resins (such as polystyrene, vinyl acetate, polyester, polyethylene, polypropylene, polyamide, rubber, or acrylic acid), thermosetting resins (such as phenol, epoxy resin, polyurethane, melamine, or alkyd resin), photosensitive resins, parylene, SiO2, etc. x or SiN x .

[0081] The first insulating layer 610 can be formed by coating a liquid insulating resin onto the surface of the body 100, coating an insulating paste onto the surface of the body 100, laminating an insulating film onto the surface of the body 100, or forming an insulating resin by vapor deposition onto the surface of the body 100. Optionally, the first insulating layer 610 can be formed by placing the material for forming the first insulating layer on a silicon die and stamping the body 100 onto the silicon die. In the case of an insulating film, a dry film (DF) including a photosensitive insulating resin, an Ajinomoto stacked film (ABF) excluding a photosensitive insulating resin, or a polyimide film, etc., can be used.

[0082] The first insulating layer 610 may have an adhesive function. For example, when an insulating film is formed by laminating the first insulating layer 610 onto the body 100, the insulating film may include an adhesive component and may adhere to the surface of the body 100. In this case, an adhesive layer may be formed separately on one surface of the first insulating layer 610. However, when the first insulating layer 610 is formed using an insulating film in a semi-cured state (stage B), a separate adhesive layer may not be formed on one surface of the first insulating layer 610.

[0083] The thickness t of the first insulating layer 610 610 The thickness can be 10 μm or less. When the thickness of the first insulating layer 610 exceeds 10 μm, the total length of the coil assembly increases, which is detrimental to size reduction, and the effective volume of the magnetic material decreases compared to a coil assembly of the same volume, potentially degrading the characteristics of the coil assembly. As described above, the coil assembly according to the embodiment can have surface roughness formed on at least a portion of the first metal layers 410 and 510, such that even when a small amount of paste is transferred, the flatness of the first insulating layer 610 can be improved, and the thickness of the first insulating layer 610 can be reduced.

[0084] The thickness t of the first insulating layer 610 610 It can be 10 nm or larger. When the thickness of the first insulating layer 610 is less than 10 nm, the characteristics of the coil assembly may be degraded, such as a decrease in the Q factor, a decrease in the breakdown voltage, and a decrease in the self-resonant frequency (SRF).

[0085] The thickness t of the first insulating layer 610 610 The measurement can be performed as follows. First, a first-direction-second-direction cross-sectional sample can be obtained by grinding the coil assembly to half its depth in the third direction (Z direction). The length of the first insulation layer 610 in the second direction (Y direction) from the obtained cross-sectional sample can be measured multiple times, and the arithmetic mean of the measurements can be used as the thickness t of the first insulation layer 610. 610 For example, the arithmetic mean of values ​​measured at five different points in a first direction (X direction) can be calculated, but embodiments thereof are not limited to this.

[0086] The second insulating layer 620 may be disposed on the first surface of the body 100, and may expose at least a portion of each of the pad portions 412 and 512. In an embodiment, the second insulating layer 620 may cover the areas of the first surface 101, second surface 102, third surface 103, fourth surface 104, fifth surface 105, and sixth surface 106 of the body 100, except for the areas where the first metal layers 410 and 510 are disposed. Specifically, in an embodiment, since the first metal layers 410 and 510 are disposed on the third surface 103 and fourth surface 104 of the body and a portion of the first surface 101, the second insulating layer 620 may cover the second surface 102, fifth surface 105, and sixth surface 106 of the body, and may be disposed on the area of ​​the first surface 101 except for the area where the pad portions 412 and 512 are disposed. The second insulating layer 620 disposed on the first surface 101, second surface 102, fifth surface 105, and sixth surface 106 of the body 100 can be formed together in the same process, so that no boundary is formed between them, but the embodiment is not limited thereto. When the first metal layers 410 and 510 of the external electrodes 400 and 500 are formed on the surface of the body 100 by plating, the second insulating layer 620 can be used as a plating resist layer. Therefore, the second insulating layer 620 can be formed on the surface of the body 100 before the formation of the first metal layers 410 and 510 of the external electrodes 400 and 500, so that the area on the surface of the body 100 in which the first metal layers 410 and 510 are formed can be defined. However, this embodiment is not limited thereto.

[0087] The second insulating layer 620 may include thermoplastic resins (such as polystyrene, vinyl acetate, polyester, polyethylene, polypropylene, polyamide, rubber, or acrylic acid), thermosetting resins (such as phenol, epoxy resin, polyurethane, melamine, or alkyd resin), photosensitive resins, parylene, SiO2, etc. x or SiN x .

[0088] The second insulating layer 620 can be formed by coating a liquid insulating resin onto the surface of the body 100, coating an insulating paste onto the surface of the body 100, laminating an insulating film onto the surface of the body 100, or forming an insulating resin by vapor deposition on the surface of the body 100. In the case of an insulating film, a dry film (DF) including a photosensitive insulating resin, an Ajinomoto stacked film (ABF) excluding a photosensitive insulating resin, or a polyimide film, etc., can be used.

[0089] The second insulating layer 620 may have an adhesive function. For example, when the second insulating layer 620 is formed by laminating an insulating film onto the body 100, the insulating film may include an adhesive component and may adhere to the surface of the body 100. In this case, an adhesive layer may be formed separately on one surface of the second insulating layer 620. However, when the second insulating layer 620 is formed using an insulating film in a semi-cured state (stage B), a separate adhesive layer may not be formed on one surface of the second insulating layer 620.

[0090] The second insulating layer 620 can be formed with a thickness ranging from 10 nm to 10 μm. When the thickness of the second insulating layer 620 is less than 10 nm, the characteristics of the coil assembly may deteriorate, such as a decrease in the Q factor, a decrease in the breakdown voltage, and a decrease in the self-resonant frequency (SRF). When the thickness of the second insulating layer 620 exceeds 10 μm, the overall length, width, and thickness of the coil assembly may increase, which may be detrimental to size reduction and reduce the effective volume of magnetic material compared to a coil assembly of the same volume, which may deteriorate the characteristics of the coil assembly.

[0091] (Second Embodiment) Figure 7 This is a diagram showing a coil assembly according to a second embodiment. Figure 8 It is shown Figure 7 A diagram of the insulating layer in the image. Figure 9 It is along Figure 7 The cross-sectional view of the coil assembly taken from line III-III' in the diagram.

[0092] Reference Figures 7 to 9 According to the second embodiment, the outer electrodes 400 and 500 of the coil assembly 2000 can be spaced apart from the second surface 102 of the body 100. Specifically, the first outer electrode 400 and the second outer electrode 500 may not extend to the second surface 102 of the body 100 and may maintain a predetermined distance from the second surface 102.

[0093] Reference Figure 8 According to the second embodiment, the main body 100 of the coil assembly 2000 may include stepped portions S1 and S2 at an edge formed by a second surface 102 and a plurality of side surfaces. Specifically, the first stepped portion S1 may be formed at an edge formed by the second surface 102 and the third surface 103 of the main body 100, and the second stepped portion S2 may be formed at an edge formed by the second surface 102 and the fourth surface 104 of the main body 100. The first stepped portion S1 and the second stepped portion S2 may extend in a third direction (Z direction) of the main body 100.

[0094] Reference Figure 9The first insulating layer 610 may be disposed in the first step portion S1 and the second step portion S2. That is, in order to prevent the outer electrodes 400 and 500 from extending excessively to the second surface 102 of the body 100, the coil assembly 2000 according to the second embodiment may form steps S1 and S2 at the edge of the body 100, and the insulating layer 610 may be disposed in the steps S1 and S2.

[0095] Apart from the above description, the description of the coil assembly 1000 according to the first embodiment can be applied as is, and a repeated detailed description may be omitted.

[0096] According to the foregoing embodiments, a coil assembly in which the surface insulating layer can have a reduced thickness so that the capacitance can be increased can be provided.

[0097] Furthermore, a coil assembly that can address defects in the coating surface insulation layer can be provided.

[0098] While embodiments have been shown and described above, it will be readily understood by those skilled in the art that modifications and variations 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 includes a first surface, a second surface opposite to the first surface in a first direction, and a plurality of side surfaces connecting the first surface to the second surface; A coil is disposed in the main body; The first and second external electrodes include a first metal layer connected to the coil and disposed on the side surface of the body; as well as A first insulating layer is disposed on the side surface of the body and covers at least a portion of the first metal layer. Wherein, a surface roughness Ry is formed on at least a portion of the surface of the first metal layer that contacts the first insulating layer, and The surface roughness Ry has an average value of 1 μm or greater.

2. The coil assembly according to claim 1, wherein, The surface roughness Ry has an average value of 10 μm or less.

3. The coil assembly according to claim 2, wherein, The thickness of the first insulating layer is 10 μm or less.

4. The coil assembly according to claim 1, in, The main body includes a stepped portion located at the edge of the main body and formed by the second surface and the plurality of side surfaces. The first insulating layer is disposed in the stepped portion.

5. The coil assembly according to claim 4, wherein, The first external electrode and the second external electrode are spaced apart from the second surface of the body.

6. The coil assembly according to claim 1, wherein, The first metal layer includes a connecting portion disposed on the side surface of the body and a pad portion extending to the first surface of the body.

7. The coil assembly according to claim 6, wherein, The connecting part is in direct contact with the coil.

8. The coil assembly according to claim 6, wherein, The first insulating layer covers at least a portion of the connection.

9. The coil assembly according to claim 6, wherein, The first insulating layer does not contact at least a portion of the pad portion.

10. The coil assembly according to claim 6, wherein, The first external electrode and the second external electrode also include a second metal layer disposed on the pad portion.

11. The coil assembly of claim 1, further comprising: Supporting components are provided in the main body. The coil includes a first coil pattern and a second coil pattern respectively disposed on one surface and another surface of the support member, as well as a first lead-out pattern and a second lead-out pattern respectively connected to the first coil pattern and the second coil pattern.

12. The coil assembly according to claim 11, wherein, The first metal layer of the first external electrode and the second external electrode is connected to the first lead-out pattern and the second lead-out pattern, respectively.

13. The coil assembly of claim 6, further comprising: A second insulating layer is disposed in the area on the first surface of the body where the first metal layer is not disposed.

14. A coil assembly, comprising: The main body includes a first surface, a second surface opposite to the first surface in a first direction, a plurality of side surfaces connecting the first surface to the second surface, and a stepped portion located at the edge formed by the second surface and the plurality of side surfaces; A coil is disposed in the main body; The first and second external electrodes include a first metal layer connected to the coil and disposed on the side surface of the body; as well as A first insulating layer is disposed on the side surface of the body and the stepped portion and covers at least a portion of the first metal layer. Surface roughness Ry is formed on at least a portion of the surface of the first metal layer that is in contact with the first insulating layer.

15. The coil assembly of claim 14, wherein, The surface roughness Ry has an average value of 10 μm or less.

16. The coil assembly of claim 14, wherein, The thickness of the first insulating layer is 10 μm or less.

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