KR20200105778A - Coil component - Google Patents

Abstract

According to an aspect of the present invention, a coil component includes: an insulating substrate; a coil unit disposed on at least one surface of the insulating substrate; and a body having an active part in which the coil unit is disposed, and a cover part disposed on the active part, wherein the insulating substrate and the coil part are embedded in the body. The ratio of the thickness T2 of the cover part to the thickness T1 of the insulating substrate satisfies 3<T2/T1<6, and the thickness T2 of the cover part satisfies 90um<T2<120um. The present invention provides the coil component capable of securing high-capacity inductance and low direct current resistance.

Description

Coil component {COIL COMPONENT}

The present invention relates to a coil component.

An inductor, one of the coil components, is a representative passive electronic component used in electronic devices along with a resistor and a capacitor.

As electronic devices become increasingly high-performance and thinner, coil components are also becoming thinner.

On the other hand, even if the coil component is thinner, since the coil component secures appropriate inductance and direct current resistance (Rdc), there is a limit to reducing the thickness of the coil of the coil component.

For this reason, in reducing the thickness of the coil component, research is being conducted to reduce at least one of the thickness of the external electrode, which is a configuration other than the coil, the thickness of the upper and lower covers respectively disposed on the upper and lower parts of the coil, and the thickness of the support substrate supporting the coil. have.

Korean Patent Registration No. 10-1442402

It is an object of the present invention to provide a coil component capable of securing a high-capacity inductance and a low direct current resistance (Rdc) while being able to achieve a low profile.

According to an aspect of the present invention, an insulating substrate; A coil unit disposed on at least one surface of the insulating substrate; And a body having an active part in which the coil part is disposed and a cover part disposed on the active part, and burying the insulating substrate and the coil part, wherein the cover part with respect to the thickness T1 of the insulating substrate A coil component is provided, wherein the ratio of the thickness T2 satisfies 3<T2/T1<6, and the thickness T2 of the cover part satisfies 90µm<T2<120µm.

According to another aspect of the invention, the body; An insulating substrate embedded in the body; And a coil unit disposed on at least an upper surface of the insulating substrate, wherein a ratio of the distance T2 from the upper surface of the coil unit to the upper surface of the body to the thickness T1 of the insulating substrate is 3<T2 A coil component is provided that satisfies /T1<6, and a distance T2 from an upper surface of the coil portion to an upper surface of the body satisfies 90㎛<T2<120㎛.

According to the present invention, it is possible to secure a high-capacity inductance and a low direct current resistance (Rdc) while reducing the thickness of the coil component (Low-profile).

1 is a view schematically showing a coil component according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a cross section taken along line II′ of FIG. 1.
3 is a view showing a cross section taken along line II-II' of FIG. 1;

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof does not preclude in advance. And, throughout the specification, the term "on" means to be positioned above or below the target portion, and does not necessarily mean to be positioned above the direction of gravity.

In addition, the term “couple” does not mean only a case in which each component is in direct physical contact with each other in the contact relationship between each component, but a different component is interposed between each component, and the component is It should be used as a concept that encompasses each contact.

Since the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, the present invention is not necessarily limited to what is shown.

In the drawings, the L direction may be defined as a first direction or a length direction, a W direction may be defined as a second direction or a width direction, and a T direction may be defined as a third direction or a thickness direction.

Hereinafter, a coil component according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, and in the description with reference to the accompanying drawings, the same or corresponding components are given the same reference numbers and overlapped descriptions thereof. Is omitted.

Various types of electronic components are used in electronic devices, and various types of coil components may be appropriately used between the electronic components for the purpose of removing noise.

In other words, coil components in electronic devices are used as power inductors, high frequency inductors (HF inductors), general beads, high frequency beads (GHz beads), and common mode filters. Can be.

1 is a view schematically showing a coil component according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a cross section taken along line II′ of FIG. 1. 3 is a diagram illustrating a cross section taken along line II-II' of FIG. 1.

1 to 3, a coil component 1000 according to an embodiment of the present invention includes a body 100, an insulating substrate 200, a coil unit 300, and external electrodes 400 and 500, and , Insulation layer 600 may be further included.

The body 100 forms the overall appearance of the coil component 1000 according to the present exemplary embodiment, and embeds the insulating substrate 200 and the coil unit 300 therein.

The body 100 may be formed in the shape of a hexahedron as a whole.

1 to 3, the body 100 includes a first surface 101 and a second surface 102 facing each other in the length direction (L), and a third surface facing each other in the width direction (W). It includes 103 and a fourth surface 104, a fifth surface 105 and a sixth surface 106 facing each other in the thickness direction T. Each of the first to fourth surfaces 101, 102, 103, and 104 of the body 100 is a wall surface of the body 100 that connects the fifth surface 105 and the sixth surface 106 of the body 100. Corresponds to. Hereinafter, both cross-sections of the body 100 refer to the first surface 101 and the second surface 102 of the body 100, and both sides of the body 100 are the third surface ( 103) and the fourth surface 104, one surface of the body 100 refers to the sixth surface 106 of the body 100, and the other surface of the body 100 is the fifth surface of the body 100 Can mean (105). In addition, hereinafter, the upper and lower surfaces of the body 100 may mean the fifth surface 105 and the sixth surface 106 of the body 100, respectively determined based on the directions of FIGS. 1 to 3. have.

The body 100 may be formed such that the coil component 1000 according to the present embodiment in which the external electrodes 400 and 500 to be described later are formed has a length of 2.0 mm, a width of 1.2 mm, and a thickness of 0.65 mm, It is not limited thereto. Alternatively, the body 100 may be formed so that the coil component 1000 according to the present embodiment 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. Alternatively, the body 100 may be formed so that the coil component 1000 according to the present embodiment 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 0.55 mm. Alternatively, the body 100 may be formed so that the coil component 1000 according to the present embodiment 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. However, since the size of the coil component 1000 according to the present embodiment described above is merely exemplary, it is not excluded from the scope of the present invention that a case formed in a size smaller than the above-described size is not excluded from the scope of the present invention.

The body 100 may include magnetic powder P and insulating resin R. Specifically, the body 100 may be formed by laminating one or more magnetic composite sheets including the insulating resin R and the magnetic powder P dispersed in the insulating resin R and then curing the magnetic composite sheet. However, the body 100 may have a structure other than the structure in which the magnetic powder P is dispersed in the insulating resin R. For example, the body 100 may be made of a magnetic material such as ferrite.

The magnetic powder P may be, for example, a ferrite or a magnetic metal powder.

Ferrite powders are, for example, Mg-Zn-based, Mn-Zn-based, Mn-Mg-based, Cu-Zn-based, Mg-Mn-Sr-based, Ni-Zn-based spinel ferrites, Ba-Zn-based, Ba -It may be at least one or more of hexagonal ferrites such as Mg-based, Ba-Ni-based, Ba-Co-based, Ba-Ni-Co-based, and Y-based garnet-type ferrite and Li-based ferrite.

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

The metal magnetic powder may be amorphous or crystalline. For example, the magnetic metal powder may be a Fe-Si-B-Cr-based amorphous alloy powder, but is not limited thereto.

Ferrite and magnetic metal powder may each have an average diameter of about 0.1 μm to 30 μm, but are not limited thereto.

The body 100 may include two or more types of magnetic powder P dispersed in the insulating resin R. Here, that the magnetic powder P is of a different type means that the magnetic powder P dispersed in the insulating resin R is distinguished from each other by any one of diameter, composition, crystallinity, and shape. For example, the body 100 may include two or more magnetic powders P having different diameters.

The insulating resin R may include, but is not limited to, epoxy, polyimide, liquid crystal polymer, or the like alone or in combination.

The body 100 includes a core C passing through the coil unit 300 to be described later. In a process of laminating and curing the magnetic composite sheet, the core C may be formed by filling the through hole of the coil unit 300 in at least a part of the magnetic composite sheet, but is not limited thereto.

The body 100 includes an active portion 110 and cover portions 120 and 130 disposed on the active portion 110. The active part 110 refers to an area in which the coil part 300 is disposed among the body 100, and the cover parts 120 and 130 refer to an area disposed on the active part 110 of the body 100. I can. As a non-limiting example, based on FIGS. 2 and 3, the active unit 110 includes a body 100 corresponding to a distance from the lower surface of the first coil pattern 311 to the upper surface of the second coil pattern 312. ), and the cover parts 120 and 130 may be defined as other areas of the body 100 disposed on each of the first and second coil patterns 311 and 312. The cover parts 120 and 130 include an upper cover part 120 which is an upper side area of the body 100 and a lower cover part 130 which is a lower side area of the body 100 with reference to FIGS. 2 and 3. Can include.

The thickness T2 of the upper cover part 120 is formed in a range of more than 90 μm and less than 120 μm. That is, the thickness T2 of the upper cover part 120 satisfies 90 μm<T2<120 μm. When the thickness T2 of the upper cover part 120 is 90 μm or less, it is difficult to secure high-capacity inductors, and when the thickness T2 of the upper cover part 120 is 120 μm or more, it is disadvantageous to thin the coil component. . Meanwhile, the above-described description of the thickness T2 of the upper cover part 120 may be applied to the lower cover part 130 as well.

As a non-limiting example, the active part 110 may be formed to have a permeability greater than that of the cover parts 120 and 130. To this end, the magnetic powder P disposed on the active part 110 may have a higher magnetic permeability than the magnetic powder P of the cover parts 120 and 130. Optionally or in parallel with this, the filling rate of the magnetic powder P of the active part 110 may be greater than the filling rate of the magnetic powder P of the cover parts 120 and 130.

The insulating substrate 200 is buried in the body 100. The insulating substrate 200 is configured to support the coil unit 300 to be described later.

The insulating substrate 200 is formed of an insulating material including a thermosetting insulating resin such as an epoxy resin, a thermoplastic insulating resin such as polyimide, or a photosensitive insulating resin, or a reinforcing material such as glass fiber or inorganic filler is impregnated with the insulating resin. It can be formed of an insulating material. For example, the insulating substrate 200 may be formed of an insulating material such as a prepreg, ABF (Ajinomoto Build-up Film), FR-4, BT (Bismaleimide Triazine) film, PID (Photo Imagable Dielectric) film, etc. However, it is not limited thereto.

As inorganic fillers, silica (SiO ₂ ), alumina (Al ₂ O ₃ ), silicon carbide (SiC), barium sulfate (BaSO ₄ ), talc, mud, mica powder, aluminum hydroxide (AlOH ₃ ), magnesium hydroxide (Mg ( OH) ₂ ), calcium carbonate (CaCO ₃ ), magnesium carbonate (MgCO ₃ ), magnesium oxide (MgO), boron nitride (BN), aluminum borate (AlBO ₃ ), barium titanate (BaTiO ₃ ) and calcium zirconate (CaZrO) At least one or more selected from the group consisting of ₃ ) may be used.

When the insulating substrate 200 is formed of an insulating material including a reinforcing material, the insulating substrate 200 may provide more excellent rigidity. When the insulating substrate 200 is formed of an insulating material that does not contain glass fibers, the insulating substrate 200 is advantageous in reducing the overall thickness of the coil unit 300. When the insulating substrate 200 is formed of an insulating material including a photosensitive insulating resin, the number of processes for forming the coil unit 300 is reduced, which is advantageous in reducing production cost, and fine vias may be formed.

The thickness T1 of the insulating substrate 200 may be greater than 20 μm and less than or equal to 30 μm. That is, 20 µm <T1 ≤ 30 µm may be satisfied. When the thickness T1 of the insulating substrate 200 is 20 μm or less, it is difficult to secure the rigidity of the insulating substrate 200 and it is difficult to support the coil unit 300 to be described later in the manufacturing process. When the thickness T1 of the insulating substrate 200 exceeds 30 μm, it is disadvantageous in reducing the thickness of the coil component.

The ratio of the thickness T2 of the upper cover part 120 to the thickness T1 of the insulating substrate 200 may be greater than 3 and less than 6. That is, 3<T2/T1<6 is satisfied. When the ratio of T2/T1 is 3 or less, the inductance may decrease. When the ratio of T2/T1 is 6 or more, the direct current resistance Rdc may increase.

The coil unit 300 is buried in the body 100 to express characteristics of a coil component. For example, when the coil component 1000 of the present embodiment is used as a power inductor, the coil unit 300 may serve to stabilize power of an electronic device by storing an electric field as a magnetic field and maintaining an output voltage.

The coil unit 300 includes coil patterns 311 and 312 and vias 320. Specifically, the first coil pattern 311 is disposed on the lower surface of the insulating substrate 200 facing the sixth surface 106 of the body 100 based on the directions of FIGS. 1, 2 and 3, A second coil pattern 312 is disposed on the upper surface of the insulating substrate 200. The vias 320 pass through the insulating substrate 200 and are connected to each other in contact with the first coil pattern 311 and the second coil pattern 312. By doing this, the coil unit 300 may function as one coil having one or more turns around the core C as a whole.

Each of the first coil pattern 311 and the second coil pattern 312 may have a planar spiral shape in which at least one turn is formed around the core C. For example, the first coil pattern 311 may form at least one turn around the core C on the lower surface of the insulating substrate 200.

At least one of the vias 320 and the coil patterns 311 and 312 may include one or more conductive layers. As an example, when the second coil pattern 312 and the via 320 are formed by plating on the upper surface of the insulating substrate 200, the second coil pattern 312 and the via 320 are respectively It may include a plating layer. Here, the electroplating layer may have a single-layer structure or a multi-layer structure. The electroplating layer of a multilayer structure may be formed in a conformal film structure in which one electroplating layer is covered by the other electroplating layer, or another electroplating layer is stacked on only one side of one electroplating layer. It may be formed in a shape. The seed layer may be formed by a method such as electroless plating or vapor deposition. In the former case, the seed layer may be formed of an electroless copper plating solution, but is not limited thereto. In the latter case, the seed layer may include at least one of titanium (Ti), chromium (Cr), nickel (Ni), and copper (Cu). The seed layer of the second coil pattern 312 and the seed layer of the via 320 may be integrally formed so that a boundary may not be formed therebetween, but the present invention is not limited thereto. The electroplating layer of the second coil pattern 312 and the electroplating layer of the via 320 may be integrally formed so that a boundary may not be formed therebetween, but is not limited thereto.

As another example, after forming the first coil pattern 311 disposed on the lower surface of the insulating substrate 200 and the second coil pattern 312 disposed on the upper surface side of the insulating substrate 200 separately from each other, the insulating substrate When the coil unit 300 is formed by collectively stacking on 200, the via 320 may include a high melting point metal layer and a low melting point metal layer having 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 containing lead (Pb) and/or tin (Sn). At least a part of the low melting point metal layer is melted due to pressure and temperature at the time of batch lamination, for example, an intermetallic compound layer (IMC layer) is formed at the boundary between the low melting point metal layer and the second coil pattern 312. I can.

Based on the directions of FIGS. 1 to 3, the coil patterns 311 and 312 may be formed to protrude from both surfaces of the insulating substrate 200, respectively. As another example, the first coil pattern 311 is formed protruding from the lower surface of the insulating substrate 200, and the second coil pattern 312 is buried in the upper surface of the insulating substrate 200 to form the second coil pattern 312. The upper surface may be exposed to the upper surface of the insulating substrate 200. In this case, a concave portion is formed on the upper surface of the second coil pattern 312, so that the upper surface of the second coil pattern 312 and the upper surface of the insulating substrate 200 may not be located on the same plane. As another example, the second coil pattern 312 is formed protruding from the upper surface of the insulating substrate 200, and the first coil pattern 311 is buried in the lower surface of the insulating substrate 200 to form the first coil pattern 311. The lower surface may be exposed to the lower surface of the insulating substrate 200. In this case, a concave portion is formed on the lower surface of the first coil pattern 311, and the lower surface of the first coil pattern 311 and the lower surface of the insulating substrate 200 may not be located on the same plane.

Each of the via 320 and the coil patterns 311 and 312 is copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), It may be formed of a conductive material such as titanium (Ti) or an alloy thereof, but is not limited thereto.

The external electrodes 400 and 500 are disposed on the surface of the body 100 and are connected to both ends of the coil unit 300 and respectively. In this embodiment, both ends of the coil unit 300 are exposed to the first and second surfaces 101 and 102 of the body 100, respectively. Accordingly, the first external electrode 400 is disposed on the first surface 101 and is in contact with the end of the first coil pattern 311 exposed to the first surface 101 of the body 100, and is connected to the second external electrode. The electrode 500 may be disposed on the second surface 102 and connected in contact with the end of the second coil pattern 312 exposed to the second surface 103 of the body 100.

The external electrodes 400 and 500 may be formed in a single layer or multiple layers structure. As an example, the first external electrode 400 is disposed on a first layer including copper, a second layer including nickel (Ni) and a second layer disposed on the first layer and containing tin (Sn). It may be composed of a third layer including. Here, each of the first to third layers may be formed by plating, but is not limited thereto. As another example, the first external electrode 400 may include a resin electrode including conductive powder and resin, and a plating layer formed by plating on the resin electrode.

The external electrodes 400 and 500 are copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), or these It may be formed of a conductive material such as an alloy of, but is not limited thereto.

The insulating film 600 may be formed on the insulating substrate 200 and the coil unit 300. The insulating film 600 is to insulate the coil unit 300 from the body 100 and may include a known insulating material such as paralin. Any insulating material included in the insulating layer 600 may be used, and there is no particular limitation. The insulating film 600 may be formed by a method such as vapor deposition, but is not limited thereto, and may be formed by laminating an insulating film on both sides of the insulating substrate 200. In the former case, the insulating layer 600 may be formed in the form of a conformal layer along the surfaces of the insulating substrate 200 and the coil unit 300. On the other hand, in the present invention, the insulating film 600 is an optional configuration, so if the body 100 can secure sufficient insulation resistance under the operating condition of the coil component 1000 according to the present embodiment, the insulating film 600 may be omitted. have.

(Experimental example)

Table 1 shows changes in inductance (L) and direct current resistance (Rdc) of Experimental Examples 1 to 8 according to varying the thickness (T1) of the insulating substrate and the thickness (T2) of the upper cover.

On the other hand, in all of Experimental Examples 1 to 8 below, the coil unit was manufactured to have the same number of turns. In addition, each turn of the coil unit was manufactured to have the same line width and the same thickness (eg, 140 μm each of the first and second coil patterns), and a space between adjacent turns of the coil unit All were prepared in the same manner. Finally, inductance (L) and direct current resistance (Rdc) were measured at the same operating frequency.

T1(㎛) T2(㎛) T2/T1 L (Ref change) Rdc (Ref change) Whether it is thinner # One 30 60.0 2.00 60.2% 98.7% Hyunghwa Park O # 2 30 80.0 2.67 80.2% 99.1% Hyunghwa Park O #3 30 195.0 6.50 116.4% 105.8% Hyunghwa Park X # 4 30 205.0 6.83 125.1% 106.0% Hyunghwa Park X #5 30 90.0 3.00 82.5% 102.1% Hyunghwa Park O #6 30 120.0 4.00 104.3% 102.6% Hyunghwa Park X #7 30 105.0 3.50 91.3% 102.3% Hyunghwa Park O # 8 30 115.0 3.83 100.3% 102.0% Hyunghwa Park O

In Table 1, L (Ref change) is 0.47 mmH as the reference value, Rdc (Ref change) is 35 mΩ as the reference value, each ratio was calculated. In Table 1, the term'thinning or not' indicates whether the thickness of the entire component formed up to the external electrode exceeds 0.60mm. Therefore, when the thickness of the whole part exceeds 0.60 mm, it is indicated as non-thinning (thinning X) in Table 1. Referring to Table 1, in the case of Experimental Examples 1, 2 and 5 in which the ratio of T2/T1 is 3 or less, When compared with Experimental Examples 7 and 8 satisfying 3<T2/T1<6, the inductance decreases. In the case of Experimental Examples 3 and 4 in which the ratio of T2/T1 is 6 or more, the inductance increases, but the direct current resistance (Rdc) increases, and thinning is impossible as compared to Experimental Examples 7 and 8 satisfying 3<T2/T1<6. In addition, referring to Table 1, in the case of Experimental Example 5 having a T2 of 90 μm or less, the inductance (L) decreases by 10% or more as compared with Experimental Examples 7 and 8 satisfying 90 μm <T2 <120 μm. In the case of Experimental Example 6 having a T2 of 120 μm or more, thinning was not possible as compared with Experimental Examples 7 and 8 satisfying 90 μm <T2 <120 μm.

In conclusion, as shown in Table 1, in the case of Experimental Examples 7 and 8 satisfying both 3<T2/T1<6 and 90㎛<T2<120㎛, it is possible to secure inductance (L) while implementing thinning. .

On the other hand, in the case of Experimental Example 7, the inductance is slightly reduced than the reference inductance, but is within the allowable range within 10% of the reference value.

By doing so, the coil component 1000 according to the present embodiment can implement a high-capacity inductance and a low direct current resistance (Rdc) while reducing the thickness of the coil component 1000.

In the above, one embodiment of the present invention has been described, but those of ordinary skill in the relevant technical field can add, change, or delete components within the scope not departing from the spirit of the present invention described in the claims. Various modifications and changes may be made to the present invention, and it will be said that this is also included within the scope of the present invention.

100: body
110: active part
120, 130: cover portion
200: insulating substrate
300: coil part
311, 312: coil pattern
320: via
400, 500: external electrode
600: insulating film
C: core
P: magnetic powder
R: insulating resin
1000: coil part

Claims (8)

Insulating substrate;
A coil unit disposed on at least one surface of the insulating substrate; And
A body having an active part in which the coil part is disposed, a cover part disposed on the active part, and burying the insulating substrate and the coil part; and
The ratio of the thickness (T2) of the cover part to the thickness (T1) of the insulating substrate satisfies 3<T2/T1<6,
The thickness of the cover part (T2) satisfies 90㎛ <T2 <120㎛,
Coil parts.
The method of claim 1,
The thickness (T1) of the insulating substrate satisfies 20㎛ <T1≤30㎛, coil component.
The method of claim 1,
The thickness of the body is 550㎛ or less (however, excluding 0), a coil component.
The method of claim 1,
The coil part
A first coil pattern having a planar spiral shape disposed on one surface of the insulating substrate,
A second coil pattern having a planar spiral shape disposed on the other surface of the insulating substrate facing one surface of the insulating substrate, and
Comprising a via passing through the insulating substrate to connect the first coil pattern and the second coil pattern,
Coil parts.
The method of claim 1,
The body includes an insulating resin and magnetic powder, the coil component.
The method of claim 1,
First and second external electrodes disposed on the surface of the body and respectively connected to both ends of the coil unit; The coil component further comprising a.
The method of claim 6,
The coil component has a thickness of 550 μm or less (excluding 0).
The method of claim 1,
An insulating film disposed between the coil unit and the body to cover the coil unit;
Further comprising,
Coil parts.

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