Coil, electrical system including the same and method of making coil

Abstract

The present invention relates to a coil and a power system including the same. Specifically, according to one embodiment of the present invention, a coil comprising: main coil surfaces that are opposite to each other and substantially planar; and a multilayer film wound to form a plurality of substantially concentric loops, wherein the plurality of loops comprises an innermost loop including a first longitudinal end of the coil and an outermost loop including a second longitudinal end of the coil, and the multilayer film comprises a plurality of first electrically conductive layers that alternate with each other; A coil may be provided comprising one or more second electrical insulating layers, wherein the first electrical conductive layer and the second electrical insulating layer have substantially coextensive width and length with each of the substantially planar main coil surfaces including corresponding end surfaces of the first electrical conductive layer and the second electrical insulating layer, and at least two of the first electrical conductive layers have different average thicknesses that reduce the AC resistance of the coil by at least 5% and at least 11.3% at a frequency of at least about 148 kHz.

Description

Technology Field

[0001] The present invention relates to a coil, a power system including the same, and a method for manufacturing a coil. Background Technology

[0002] Portable electronic devices with built-in batteries, such as smartphones, PDAs, and tablets, need to be charged with power. Recently, systems that wirelessly transmit power are widely used to charge batteries embedded in portable electronic devices. These wireless power charging systems (WPC) transmit and receive power using electromagnetic induction or resonance, and for this purpose, coils are provided inside the electronic device and the wireless charging system.

[0003] In addition, portable electronic devices can provide various functions such as wireless charging systems, Near Field Communication (NFC), and Magnetic Secure Transmission (MST). In particular, portable electronic devices are equipped with multiple coils inside to perform near-field communication and wireless electronic payment systems.

[0004] As such, multiple coils are installed inside the portable electronic device to independently perform wireless charging systems, near-field wireless communication systems, and wireless electronic payment systems. The problem to be solved

[0005] Generally, in coils wound with multiple turns, the distribution of current flowing through the coil cross-section changes due to the proximity effect caused by eddy currents, and this current changes in a direction that reduces the effective cross-sectional area through which current can flow within the coil. Meanwhile, conventional coils have a small effective cross-sectional area through which current can flow, so the resistance of the coil increases relative to the DC resistance. Furthermore, as the operating frequency increases, the effective cross-sectional area of ​​the coil decreases rapidly, so some of the energy stored in the coil during wireless charging is consumed as heat. As a result, the wireless charging efficiency through the coil is reduced.

[0006] One embodiment of the present invention was developed based on the background described above, and aims to provide a coil and a wireless charging system capable of increasing the effective cross-sectional area of ​​the current flowing through the coil to lower the AC resistance of the coil and increase the efficiency of wireless charging. means of solving the problem

[0007] According to one aspect of the present invention, a coil may be provided comprising: main coil surfaces that are substantially planar and opposite to one another; and a multilayer film wound to form a plurality of substantially concentric loops, wherein the plurality of loops include an innermost loop including a first longitudinal end of the coil and an outermost loop including a second longitudinal end of the coil, and the multilayer film comprises a plurality of alternating first electrically conductive layers; and one or more second electrically insulating layers, wherein the first electrically conductive layers and the second electrically insulating layers have a width and length that are substantially coextensive with each other such that each of the substantially planar main coil surfaces includes corresponding end surfaces of the first electrically conductive layers and the second electrically insulating layers, and at least two of the first electrically conductive layers have different average thicknesses that reduce the AC resistance of the coil by at least 5% and at least 11.3% at a frequency of at least about 148 kHz.

[0008] Additionally, a coil may be provided comprising a multilayer film wound to form a plurality of substantially concentric loops, wherein the multilayer film comprises a plurality of first electrically conductive layers spaced apart from each other in the thickness direction, and at least two adjacent first electrically conductive layers comprise a second adhesive layer disposed between the two adjacent first electrically conductive layers, and at least one of the plurality of first electrically conductive layers is disposed on a third magnetically conductive layer, and the first electrically conductive layer, the second adhesive layer, and the third magnetically conductive layer have a width and length that are substantially coextensive from each other such that each of the substantially planar main coil surfaces includes corresponding end surfaces of the first electrically conductive layer, the second adhesive layer, and the third magnetically conductive layer, and the at least two first electrically conductive layers have different average thicknesses that reduce the AC resistance of the coil by at least 3% and at least 6.6% at a frequency of at least about 143 kHz. Effects of the invention

[0009] One embodiment of the present invention has the effect of reducing the AC resistance of a coil.

[0010] In addition, it involves a small temperature rise during wireless charging and has the effect of charging the battery faster. Brief explanation of the drawing

[0011] FIG. 1 is a conceptual diagram of a power system according to a first embodiment of the present invention. Figure 2 is a plan view of the coil of Figure 1. Figure 3 is a partial perspective view of the multilayer film of Figure 2. Figure 4 is a plan view of Figure 3. Figure 5 is a cross-sectional view taken along A-A' of Figure 2. FIG. 6 is a graph comparing the AC resistance values ​​of a coil according to the first embodiment of the present invention and a comparative example. FIG. 7 is a drawing showing a multilayer film according to the first embodiment of the present invention wound on a rod. Figure 8 is a cross-sectional view taken along B-B' of Figure 7. Figure 9 is a drawing showing the cross-section of the rod in Figure 8 as a polygon. FIG. 10 is a flowchart sequentially illustrating a method for manufacturing a coil according to a first embodiment of the present invention. FIG. 11 is a partial perspective view of a multilayer film according to a second embodiment of the present invention. FIG. 12 is a coil and an enlarged view according to a third embodiment of the present invention. FIG. 13 is a partial perspective view of a multilayer film according to a fourth embodiment of the present invention. Specific details for implementing the invention

[0012] Hereinafter, specific embodiments for implementing the technical concept of the present invention will be described in detail with reference to the drawings.

[0013] In addition, in describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0014] Furthermore, when it is mentioned that one component is 'connected,' 'combined,' or 'contacted' with another component, it should be understood that while the connection, combination, or contact may be direct, there may also be other components present in between.

[0015] The terms used in this specification are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0016] Furthermore, it should be noted in advance that expressions such as upper side, lower side, etc. in this specification are described based on the drawings, and may be expressed differently if the orientation of the object changes. For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted, and the size of each component does not entirely reflect its actual size.

[0017] Additionally, terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but such components are not limited by such terms. These terms are used solely for the purpose of distinguishing one component from another.

[0018] The meaning of "comprising" as used in the specification is to specify certain characteristics, regions, integers, steps, actions, elements, and / or components, and does not exclude the existence or addition of other specific characteristics, regions, integers, steps, actions, elements, components, and / or groups.

[0019] Meanwhile, in this specification, the width direction refers to the x-axis direction of FIG. 3, and the length direction refers to the y-axis direction of FIG. 3. In addition, the thickness direction refers to the z-axis direction of FIG. 3.

[0020] Hereinafter, the specific configuration of the power system (1) according to the first embodiment of the present invention will be described with reference to the drawings.

[0021] Referring to FIG. 1 below, a power system (1) according to a first embodiment of the present invention can be installed in a portable electronic device such as a smartphone, PDA, or tablet and can provide various functions. For example, the power system (1) can provide a wireless power charging function (WPC) for wirelessly charging a battery and can transmit and receive power through electromagnetic induction. In addition, the power system (1) can provide one or more functions among a near-field communication system (NFC) and a magnetic secure transmission system (MST). Such a power system (1) may include a wireless charging system (10) and an electric circuit (20).

[0022] The wireless charging system (10) can supply power wirelessly to the electric circuit (20). Additionally, the electric circuit (20) can be configured to be wirelessly charged by the wireless charging system (10).

[0023] Meanwhile, the wireless charging system (10) may include a substantially flat coil (100).

[0024] Referring to FIG. 2, the coil (100) can provide a portion through which current flows. This coil (100) may include a multilayer film (110).

[0025] Referring to FIGS. 3 to 5, the multilayer film (110) may have a multilayer structure and may include a conductive material through which current flows. The multilayer film (110) may include a first electrically conductive layer (111) and a second electrically insulating layer (112).

[0026] The first electrically conductive layer (111) may include a metallic material through which current can flow. Additionally, the first electrically conductive layer (111) may be magnetically insulative. The first electrically conductive layer (111) may be provided in multiple numbers, and the multiple first electrically conductive layers (111) may be arranged alternately with each other. Additionally, the multiple first electrically conductive layers (111) may have different average thicknesses. For example, two or more first electrically conductive layers (111) may have different average thicknesses that reduce the AC resistance of the coil (100) by 5% or more and 11.3% or less at a frequency of about 148 kHz or higher. As a more detailed example, two or more first electrically conductive layers (111) may have different average thicknesses that reduce the AC resistance of the coil (100) by at least 5%, 6%, 7%, 8%, 9%, 10%, 11%, or 11.3% at a frequency of about 148 kHz or higher.

[0027] A second electrical insulating layer (112) may be disposed between these two adjacent first electrically conductive layers (111). Meanwhile, in this specification, the first electrically conductive layer (111) may include a metal, and as an example, may include copper.

[0028] Referring to FIG. 6, the coil (100) according to the first embodiment of the present invention has an AC resistance value that is 11.3% lower than that of a conventional coil (100). In FIG. 6, the single copper in the comparative example refers to a single copper layer of the multilayer film (110), and the uniform multiple coppers represent the AC resistance value when multiple copper layers have the same thickness. Additionally, the non-uniform multiple coppers #1 to #3 refer to three coils (100) in which multiple copper layers have different average thicknesses. That is, they refer to three different coils (100) according to the first embodiment.

[0029] In this way, by having multiple first electrical conductive layers (111) with different thicknesses, the electrical resistance value of the coil (100) is lowered, and the charging efficiency of the wireless charging system (10) is increased.

[0030] One or more second electrical insulating layers (112) are provided and can insulate between two adjacent first electrically conductive layers (111). These second electrical insulating layers (112) may include an adhesive layer (112a) and a magnetically conductive layer (112b). For example, at least one of the one or more second electrical insulating layers (112) may be an adhesive layer (112a). Additionally, at least one of the one or more second electrical insulating layers (112) may be a magnetically conductive layer (112b).

[0031] The adhesive layer (112a) can connect the first electrically conductive layer (111) and the magnetically conductive layer (112b), and can connect two adjacent first electrically conductive layers (111). Additionally, the adhesive layer (112a) can connect adjacent loops (120) when the multilayer film (110) forms a loop (120) to be described later. This adhesive layer (112a) may, for example, include an adhesive material.

[0032] The magnetic conductive layer (112b) may include a magnetic material. This magnetic conductive layer (112b) may be connected to the first electrical conductive layer (111) through the adhesive layer (112a). This magnetic conductive layer (112b) may be provided in multiple numbers. For example, one of the multiple magnetic conductive layers (112b) may be placed between the first electrical conductive layer (111) and the adhesive layer (112a). Additionally, another of the multiple magnetic conductive layers (112b) may be placed at the outermost edge in the thickness direction of the multilayer film (110). The magnetic conductive layer (112b) placed at the outermost edge in the thickness direction of the multilayer film (110) may be connected to the adhesive layer (112a) of an adjacent loop (120) when the multilayer film (110) forms a loop (120).

[0033] For example, the magnetic conductive layer (112b) may include one or more of a magnetically conductive ferrite, a magnetically conductive soft magnet, a magnetically conductive metal, a magnetically conductive crystalline alloy, a magnetically conductive nanocrystalline alloy, a magnetically conductive amorphous alloy, and a magnetically conductive composite.

[0034] Additionally, the magnetically conductive ferrite included in the magnetically conductive layer (112b) may include one or more of manganese-zinc ferrite and nickel-zinc ferrite.

[0035] Additionally, the magnetically conductive soft magnet included in the magnetically conductive layer (112b) may have coercivity greater than 0 A / m and less than 1000 A / m. For example, the magnetically conductive soft magnet may have coercivity less than 1000 A / m, less than 100 A / m, less than 50 A / m, or less than 20 A / m. In other words, the magnetically conductive soft magnet included in the magnetically conductive layer (112b) may have coercivity less than 20 A / m, but may also have coercivity less than 1000 A / m.

[0036] Additionally, the magnetically conductive metal included in the magnetically conductive layer (112b) may include a magnetically conductive alloy containing iron. Here, the magnetically conductive alloy may include one or more of silicon, aluminum, boron, niobium, copper, cobalt, nickel, and molybdenum.

[0037] Additionally, the magnetically conductive crystalline alloy included in the magnetically conductive layer (112b) may include two or more of iron, cobalt, and nickel.

[0038] Additionally, the nanocrystalline alloy included in the magnetic conductive layer (112b) may include iron, silicon, boron, niobium, and copper.

[0039] Additionally, the magnetically conductive amorphous alloy included in the magnetically conductive layer (112b) may include one or more of silicon and boron and cobalt or iron.

[0040] Additionally, the magnetically conductive composite included in the magnetically conductive layer (112b) may include particles dispersed in a binder. Here, the particles dispersed in the binder may include metallic particles, and as an example, the metallic particles may include an iron-aluminum-silicon alloy.

[0041] Meanwhile, referring again to FIG. 2, the coil (100) may be wound to form a plurality of substantially concentric loops (120). In other words, the multilayer film (110) may be provided such that a long, straight film is wound multiple times to form a plurality of loops (120). In this specification, the meaning of a plurality of loops (120) being formed is that the multilayer film (110) is wound multiple times to surround a predetermined center. Additionally, the concept of a plurality of loops (120) may include not only loops with different centers but also multiple loops with the same center. Furthermore, the plurality of loops may be formed by separate coils, but they may also be connected to each other and formed by a single coil. These plurality of loops (120) may include an innermost loop (121) and an outermost loop (122).

[0042] The innermost loop (121) is the innermost loop (120) among the plurality of loops (120) and may include a first longitudinal end (121a) which is one end of the coil (100).

[0043] The outermost loop (122) is the outermost loop (120) among the plurality of loops (120) and may include a second longitudinal end (122a) which is the other end of the coil (100).

[0044] Here, the first longitudinal end (121a) refers to one end in the longitudinal direction of the multilayer film (110), and the second longitudinal end (122a) refers to the opposite end in the longitudinal direction of the multilayer film (110). Additionally, the longitudinal direction may be the direction in which the multilayer film (110) extends.

[0045] Meanwhile, referring to FIG. 4, the coil (100) may include main coil surfaces (130, 140). These main coil surfaces (130, 140) may be formed extending between a first longitudinal end (121a) and a second longitudinal end (122a). Additionally, the main coil surfaces (130, 140) may be opposite each other and substantially flat. These main coil surfaces (130, 140) may include a first main coil surface (130) which is one side of the multilayer film (110) and a second main coil surface (140) which is the other side of the multilayer film (110).

[0046] The first main coil surface (130) may include a first electrically conductive layer end surface (131) and a first electrically insulating layer end surface (132).

[0047] The second main coil surface (140) may include a second electrically conductive layer end surface (141) and a second electrically insulating layer end surface (142).

[0048] Here, the first electrical conductive layer end surface (131) and the second electrical conductive layer end surface (141) refer to the two end surfaces in the width direction of the first electrical conductive layer (111). Additionally, the first electrical insulating layer end surface (132) and the second electrical insulating layer end surface (142) refer to the two end surfaces in the width direction of the second electrical insulating layer (112).

[0049] Meanwhile, in this specification, the first electrically conductive layer end surface (131), the first electrically insulating layer end surface (132), the second electrically conductive layer end surface (141), and the second electrically insulating layer end surface (142) may be referred to as corresponding end surfaces (131, 132, 141, 142). Additionally, the main coil surfaces (130, 140) may include the corresponding end surfaces (131, 132, 141, 142).

[0050] Additionally, the first electrically conductive layer (111) and the second electrically insulating layer (112) may have substantially coextensive width (W) and length (L) such that the first main coil surface (130) and the second main coil surface (140), which are substantially flat, each include corresponding end surfaces (131, 132, 141, 142) of the first electrically conductive layer (111) and the second electrically insulating layer (112). In other words, the first electrically conductive layer (111) and the second electrically insulating layer (112) may be extended to have the same width (W) and length (L).

[0051] In this way, by having multiple first electrical conductive layers (111) with different thicknesses, the electrical resistance value of the coil (100) is lowered, and the charging efficiency of the wireless charging system (10) is increased.

[0052] Hereinafter, a coil manufacturing method (S10) for manufacturing a coil (100) according to a first embodiment of the present invention will be described with reference to FIGS. 7 to 10.

[0053] The coil manufacturing method (S10) may include the steps of providing a multilayer film (S100), winding the multilayer film (S200), curing the multilayer film (S300), and cutting the multilayer film (S400).

[0054] In the step (S100) of providing a multilayer film, a multilayer film (110) may be provided that includes a plurality of alternating first electrically conductive layers (111) and one or more second electrically insulating layers (112).

[0055] In the step (S200) of winding the multilayer film, the multilayer film (110) can be wound around a longitudinal axis. In this case, the multilayer film (110) centered substantially on the longitudinal axis may include substantially concentric turns. Additionally, the multilayer film (110) may be wound around a long rod (2) centered substantially on the longitudinal axis. In this specification, the meaning of turns refers to a state in which the multilayer film (110) is wound multiple times around the long rod (2). Additionally, multiple turns mean that their centers are identical. Here, the long rod (2) may have a circular or polygonal cross-section and may extend along the longitudinal axis.

[0056] In the step of curing the multilayer film (S300), the multilayer film (110) wound multiple times can be cured. In the step of curing the multilayer film (S300), the temperature and time for curing the multilayer film (110) may vary depending on the type of epoxy and the curing agent. For example, in the step of curing the multilayer film (S300), the multilayer film (110) wound on a long rod (2) can be cured by exposing it to a high temperature for a predetermined time, or it can be cured at room temperature.

[0057] In the step (S400) of cutting the multilayer film, the multilayer film (110), which has been wound multiple times to form a coil (100), may be cut in a direction substantially perpendicular to the longitudinal axis. In this case, the multilayer film (110) is cut into multiple coils (100), and the coil (100) may include multiple loops (120) that are substantially concentric of the multilayer film (110).

[0058] Meanwhile, in addition to this configuration, according to the second embodiment of the present invention, the multilayer film (110) may include a first electrically conductive layer (111), a second adhesive layer (113), and a third magnetically conductive layer (114). Hereinafter, the second embodiment of the present invention will be described with further reference to FIG. 11. In describing the second embodiment, the differences when compared with the above-described embodiment will be described mainly, and the same descriptions and reference numerals will be taken from the above-described embodiment.

[0059] The multilayer film (110) may include a first electrically conductive layer (111), a second adhesive layer (113), and a third magnetically conductive layer (114).

[0060] The first electrically conductive layer (111) may be provided in multiple numbers, and the multiple first electrically conductive layers (111) may have different average thicknesses. For example, two or more first electrically conductive layers (111) may have different average thicknesses that reduce the AC resistance of the coil (100) by 3% or more and 6.6% or less at a frequency of about 143 kHz or higher. As a more detailed example, two or more first electrically conductive layers (111) may have different average thicknesses that reduce the AC resistance of the coil (100) by at least 3%, 4%, 5%, 6%, or 6.6% at a frequency of about 148 kHz or higher.

[0061] The second adhesive layer (113) can connect the first electrically conductive layer (111) and the third magnetically conductive layer (114). Additionally, the second adhesive layer (113) can be positioned between at least two adjacent first electrically conductive layers (111) to connect the two adjacent first electrically conductive layers (111) to each other.

[0062] The third magnetic conductive layer (114) may include a magnetic material. Additionally, at least one of a plurality of first electrical conductive layers (111) may be disposed on the third magnetic conductive layer (114).

[0063] Meanwhile, the first main coil surface (130) may include a first electrically conductive layer end surface (131), a first adhesive layer end surface (133), and a first magnetically conductive layer end surface (134).

[0064] The second main coil surface (140) may include a second electrically conductive layer end surface (141), a second adhesive layer end surface (143), and a second magnetically conductive layer end surface (144).

[0065] Here, the first electrical conductive layer end surface (131) and the second electrical conductive layer end surface (141) refer to the two end surfaces in the width direction of the first electrical conductive layer (111). Additionally, the first adhesive layer end surface (133) and the second adhesive layer end surface (143) refer to the two end surfaces in the width direction of the second adhesive layer (113). Furthermore, the first magnetic conductive layer end surface (134) and the second magnetic conductive layer end surface (144) refer to the two end surfaces in the width direction of the third magnetic conductive layer (114).

[0066] Additionally, in this specification, the first electrically conductive layer end surface (131), the first adhesive layer end surface (133), the first magnetically conductive layer end surface (134), the second electrically conductive layer end surface (141), the second adhesive layer end surface (143), and the second magnetically conductive layer end surface (144) may be referred to as corresponding end surfaces (131, 133, 134, 141, 143, 144). Additionally, the main coil surfaces (130, 140) may include the corresponding end surfaces (131, 133, 134, 141, 143, 144).

[0067] Additionally, the first electrically conductive layer (111), the second adhesive layer (113), and the third magnetically conductive layer (114) may have substantially coextensive widths (W) and lengths (L) such that the first main coil surface (130) and the second main coil surface (140), which are substantially flat, each include corresponding end surfaces (131, 133, 134, 141, 143, 144). In other words, the first electrically conductive layer (111), the second adhesive layer (113), and the third magnetically conductive layer (114) may be extended to have the same width (W) and length (L).

[0068] Meanwhile, in addition to this configuration, according to the third embodiment of the present invention, the loop (120) may include a metal layer (123) and a non-metal layer (124). Hereinafter, the third embodiment of the present invention will be described with further reference to FIG. 12. In describing the third embodiment, the differences when compared with the above-described embodiment will be described mainly, and the same descriptions and reference numerals will be taken from the above-described embodiment.

[0069] The coil (100) may include a plurality of concentric loops (120). Each of these concentric loops (120) may include a metal layer (123) and a non-metal layer (124) substantially identical to the loop (120).

[0070] The metal layer (123) may include a metal material through which current can flow. For example, the metal layer (123) may include copper. Additionally, the metal layers (123) of a plurality of loops (120) may have different average thicknesses. For example, the metal layers (123) of two or more concentric loops (120) may have different average thicknesses that reduce the charging time by the wireless charging system (10) by 3% or more and 6.6% or less at a frequency of about 143 kHz or higher. As a more detailed example, the metal layers (123) of two or more concentric loops (120) may have different average thicknesses that reduce the charging time by the wireless charging system (10) by at least 3%, 4%, 5%, 6%, 7%, 8%, or 8.5% at a frequency of about 143 kHz or higher.

[0071] A non-metal layer (124) can connect adjacent metal layers (123) to each other. For example, the non-metal layer (124) may include epoxy. This non-metal layer (124) may be opposite to the metal layer (123) of an adjacent loop (120).

[0072] Meanwhile, in addition to this configuration, according to the fourth embodiment of the present invention, the multilayer film (110) may include a mixed layer (115) and a mixed adhesive layer (116). Hereinafter, the fourth embodiment of the present invention will be described with further reference to FIG. 13. In describing the fourth embodiment, the differences when compared with the above-described embodiment will be described mainly, and the same descriptions and reference numerals will be taken from the above-described embodiment.

[0073] The mixed layer (115) may be provided in multiple numbers, and the multiple mixed layers (115) may be arranged along the thickness direction relative to each other. For example, the mixed layer (115) may be named as a Flexible Copper Clad Laminate (FCCL) layer. This mixed layer (115) may include a mixed electrically conductive layer (115a) and a connecting layer (115b).

[0074] The mixed electrically conductive layer (115a) may be provided in multiple numbers and may be connected to one another by a connecting layer (115b). For example, the mixed electrically conductive layer (115a) may include copper.

[0075] The connecting layer (115b) can connect adjacent mixed electrically conductive layers (115a) to each other. For example, the connecting layer (115b) may include polyimide (PI).

[0076] The mixed adhesive layer (116) can connect adjacent mixed layers (115) to each other.

[0077] In this way, by connecting the mixed electrical conductive layers (115a) to each other by the connecting layer (115b), the partial shorting of the surface of the coil (100) due to burrs or metal particles when cutting the coil (100) can be minimized. Additionally, by placing the connecting layer (115b) between the mixed electrical conductive layers (115a), the area of ​​the mixed electrical conductive layer (115a) is increased for the same thickness.

[0078] Meanwhile, in addition to this configuration, according to the fifth embodiment of the present invention, the multilayer film (110) may include a first electrically conductive layer (111) and a second electrically insulating layer (112). In the fifth embodiment, the first electrically conductive layer (111) and the second electrically insulating layer (112) are described by reference in the first embodiment.

[0079] Referring to FIG. 14, each of the multiple loops (120) formed by winding the multilayer film (110) multiple times may include a first electrically conductive layer (111), an adhesive layer (112a), and a magnetically conductive layer (112b). In other words, the multilayer film (110) within one loop (120) may include a first electrically conductive layer (111), an adhesive layer (112a), and a magnetically conductive layer (112b), as shown in the cross-section of FIG. 14. As a result, one loop (120) may include multiple first electrically conductive layers (111), and the magnetically conductive layer (112b) may be placed between the multiple first electrically conductive layers (111) included in one loop (120).

[0080] As a result, the AC resistance of the coil (100) is lowered at high frequencies ranging from hundreds of kHz to several MHz, and the charging efficiency of the wireless charging system (10) is increased. Referring to Table 1 below, the Q-factor value of the coil (100) according to the fifth embodiment has the effect of increasing by 24% compared to the Q-factor value of the sixth embodiment to be described later. Here, the Q-factor value follows Equation 1 below.

[0081] [Formula 1]

[0082] Q-factor = (2πFL) / R

[0083] (F: Frequency, L: Inductance, R: Resistance)

[0084] Q-factor Fifth embodiment 194 6th embodiment 156 Increase / decrease 24%

[0085] Additionally, referring to FIG. 16, the AC resistance of the coil (100) according to the fifth embodiment has the effect of being lower than the AC resistance according to the sixth embodiment at the same frequency.

[0086] However, in FIG. 14, the first electrical conductive layer (111) of each of the plurality of loops (120) is shown to have the same thickness, but the present invention is not limited by this, and the thickness of the first electrical conductive layer (111) may be different.

[0087] Meanwhile, in addition to this configuration, according to the sixth embodiment of the present invention, the multilayer film (110) may include a first electrically conductive layer (111) and an adhesive layer (112a). In the sixth embodiment, the first electrically conductive layer (111) and the adhesive layer (112a) are described by reference in the first embodiment.

[0088] Referring to FIG. 15, the first electrically conductive layer (111) may be configured to allow current to flow. This first electrically conductive layer (111) may include a metallic material capable of allowing current to flow, and may include copper, for example. Additionally, the first electrically conductive layer (111) may be provided in multiple numbers.

[0089] The adhesive layer (112a) can insulate two adjacent first electrically conductive layers (111) and can bond two adjacent first electrically conductive layers (111). Multiple such adhesive layers (112a) may be provided. Additionally, the adhesive layer (112a) may include an adhesive material, and, for example, may include epoxy.

[0090] Meanwhile, within one loop (120), a plurality of first electrically conductive layers (111) and a plurality of adhesive layers (112a) may be arranged alternately.

[0091] The following is a list of embodiments of the present invention.

[0092] Item 1 is a coil comprising: main coil surfaces that are opposite to each other and substantially flat; and a multilayer film wound to form a plurality of substantially concentric loops, wherein the plurality of loops include an innermost loop including a first longitudinal end of the coil and an outermost loop including a second longitudinal end of the coil, and wherein the multilayer film comprises a plurality of alternating first electrically conductive layers; and one or more second electrically insulating layers, wherein the first electrically conductive layers and the second electrically insulating layers have a width and length that are substantially coextensive with each other such that each of the substantially flat main coil surfaces includes corresponding end surfaces of the first electrically conductive layers and the second electrically insulating layers, and two or more of the first electrically conductive layers have different average thicknesses that reduce the AC resistance of the coil by 5% or more and 11.3% or less at a frequency of about 148 kHz or higher.

[0093] Item 2 is a coil in which at least one of the above one or more second electrical insulating layers is an adhesive layer.

[0094] Item 3 is a coil in which at least one of the above one or more second electrical insulating layers is a magnetic conductive layer.

[0095] Item 4 is a coil in which the magnetic conductive layer comprises one or more of a magnetically conductive ferrite, a magnetically conductive soft magnet, a magnetically conductive metal, a magnetically conductive crystalline alloy, a magnetically conductive nanocrystalline alloy, a magnetically conductive amorphous alloy, and a magnetically conductive composite.

[0096] Item 5 is a coil in which the magnetically conductive ferrite comprises one or more of manganese-zinc ferrite and nickel-zinc ferrite.

[0097] Item 6 is a coil in which the above-mentioned magnetically conductive soft magnet has a coercivity greater than 0 A / m and less than 1000 A / m.

[0098] Item 7 is a coil in which the magnetically conductive metal comprises a magnetically conductive alloy containing iron.

[0099] Item 8 is a coil in which the magnetically conductive alloy further comprises one or more of silicon, aluminum, boron, niobium, copper, cobalt, nickel, and molybdenum.

[0100] Item 9 is a coil in which the magnetically conductive alloy further comprises one or more of silicon, boron, niobium, and copper.

[0101] Item 10 is a coil in which the magnetically conductive crystalline alloy comprises two or more of iron, cobalt, and nickel.

[0102] Item 11 is a coil of the magnetically conductive nanocrystalline alloy comprising iron, silicon, boron, niobium, and copper.

[0103] Item 12 states that the above-mentioned magnetically conductive amorphous alloy comprises one or more of silicon and boron and one or more of cobalt and iron,

[0104] It is a coil.

[0105] Item 13 is a coil in which the magnetically conductive composite comprises particles dispersed in a binder.

[0106] Item 14 is a coil in which the above particles include metallic particles.

[0107] Item 15 is a coil in which the metallic particles described above include an iron-aluminum-silicon alloy.

[0108] Item 16 is a coil in which at least one of the above one or more second electrical insulating layers comprises an adhesive layer and a magnetically conductive layer disposed on the adhesive layer.

[0109] Item 17 states that the first electrically conductive layer is a magnetically insulative coil.

[0110] Item 18 is a coil in which the first electrically conductive layer comprises a metal.

[0111] Item 19 comprises a multilayer film wound to form a plurality of substantially concentric loops, said multilayer film comprising: a plurality of first electrically conductive layers spaced apart from each other in the thickness direction; a second adhesive layer disposed between two or more adjacent first electrically conductive layers; and

[0112] The coil comprises a third magnetic conductive layer, wherein one or more of the plurality of first electrical conductive layers are disposed on the third magnetic conductive layer, and the first electrical conductive layer, the second adhesive layer, and the third magnetic conductive layer have substantially coextensive widths and lengths such that each of the substantially planar main coil surfaces includes corresponding end surfaces of the first electrical conductive layer, the second adhesive layer, and the third magnetic conductive layer, and the two or more first electrical conductive layers have different average thicknesses that reduce the AC resistance of the coil by 3% or more and 6.6% or less at a frequency of about 143 kHz or higher.

[0113] Item 20 is a power system comprising: a wireless charging system comprising a substantially planar coil comprising a plurality of concentric loops; and an electric circuit configured to be wirelessly charged by the wireless charging system, wherein each of the concentric loops comprises a metal layer substantially aligned with the loop, and the metal layers of two or more of the concentric loops have different average thicknesses that reduce the charging time by the wireless charging system by 3% or more and 6.6% or less at a frequency of about 143 kHz or higher.

[0114] Item 21 is a method for manufacturing a coil, comprising the steps of: providing a multilayer film comprising a plurality of alternating first electrically conductive layers; and one or more second electrically insulating layers; winding the multilayer film to form a multilayer film wound around a longitudinal axis, said multilayer film comprising a plurality of substantially concentric turns of said multilayer film centered substantially on a longitudinal axis; and cutting said multilayer film in a direction substantially perpendicular to said longitudinal axis to form a coil, said coil comprising a plurality of substantially concentric loops of said multilayer film, said loop comprising an innermost loop including a first longitudinal end of said coil and an outermost loop including a second longitudinal end of said coil, said coil comprising main coil surfaces that are opposite to each other and substantially flat.

[0115] Item 22 is a method for manufacturing a coil in which the above multilayer film is substantially wound around an elongated rod centered on the longitudinal axis.

[0116] Item 23 is a method for manufacturing a coil in which the above-mentioned long rod includes a substantially circular cross-section.

[0117] Item 24 is a method for manufacturing a coil in which the above-mentioned long rod substantially comprises a polygonal cross-section.

[0118] Although the embodiments of the present invention have been described above as specific embodiments, they are merely examples and the present invention is not limited thereto, but should be interpreted as having the broadest scope in accordance with the technical concept disclosed in this specification. Those skilled in the art may implement patterns of shapes not specified by combining or substituting the disclosed embodiments, and this also does not deviate from the scope of the present invention. Furthermore, those skilled in the art may easily modify or alter the disclosed embodiments based on this specification, and it is evident that such modifications or alterations also fall within the scope of the rights of the present invention. Explanation of the symbols

[0119] 1: Power System 2: Load 10: Wireless charging system 20: Electric circuit 100: Coil 110: Multilayer film 111: First electrically conductive layer 112: Second electrical insulation layer 112a: Adhesive layer 112b: Magnetic conductive layer 113: Second adhesive layer 114: Third magnetic conduction layer 115: Mixed layer 115a: Mixed electrically conductive layer 115b: Connecting layer 116: Mixed adhesive layer 120: Loop 121: Innermost loop 121a: First longitudinal end 122: Outermost loop 122a: Second longitudinal end 123: Metal layer 124: Non-metal layer 130: Surface of the first main coil 131: End surface of the first electrically conductive layer 132: End surface of the first electrical insulation layer 133: End surface of the first adhesive layer 134: End surface of the first magnetic conductive layer 140: Surface of the second main coil 141: End surface of the second electrically conductive layer 142: End surface of the second electrically insulating layer 143: End surface of the second adhesive layer 144: End surface of the second magnetic conductive layer

Claims

Claim 1 A coil comprising: main coil surfaces that are opposite to each other and substantially flat; and a multilayer film wound to form a plurality of substantially concentric loops, wherein the plurality of loops include an innermost loop including a first longitudinal end of the coil and an outermost loop including a second longitudinal end of the coil, wherein the multilayer film comprises a plurality of alternating first electrically conductive layers; and one or more second electrically insulating layers, wherein the first electrically conductive layers and the second electrically insulating layers have a width and length that are substantially coextensive with each other such that each of the substantially flat main coil surfaces includes corresponding end surfaces of the first electrically conductive layers and the second electrically insulating layers, and two or more of the first electrically conductive layers have different average thicknesses that reduce the AC resistance of the coil by 5% or more and 11.3% or less at a frequency of 148 kHz or higher. Claim 2 A coil according to claim 1, wherein at least one of the one or more second electrical insulation layers is an adhesive layer. Claim 3 A coil according to claim 1, wherein at least one of the one or more second electrical insulating layers is a magnetic conductive layer. Claim 4 In claim 3, the magnetic conductive layer comprises one or more of a magnetically conductive ferrite, a magnetically conductive soft magnet, a magnetically conductive metal, a magnetically conductive crystalline alloy, a magnetically conductive nanocrystalline alloy, a magnetically conductive amorphous alloy, and a magnetically conductive composite, forming a coil. Claim 5 In claim 4, the magnetically conductive ferrite comprises one or more of manganese-zinc ferrite and nickel-zinc ferrite, forming a coil. Claim 6 In claim 4, the magnetically conductive soft magnet is a coil having coercivity greater than 0 A / m and less than 1000 A / m. Claim 7 In claim 4, the coil comprises a magnetically conductive metal comprising a magnetically conductive alloy containing iron. Claim 8 In claim 7, the magnetically conductive alloy further comprises one or more of silicon, aluminum, boron, niobium, copper, cobalt, nickel, and molybdenum, forming a coil. Claim 9 In claim 7, the magnetically conductive alloy further comprises one or more of silicon, boron, niobium, and copper, forming a coil. Claim 10 In claim 4, the magnetically conductive crystalline alloy comprises two or more of iron, cobalt, and nickel, forming a coil. Claim 11 In claim 4, the magnetically conductive nanocrystalline alloy comprises a coil comprising iron, silicon, boron, niobium, and copper. Claim 12 In claim 4, the magnetically conductive amorphous alloy comprises one or more of silicon and boron and one or more of cobalt and iron, forming a coil. Claim 13 In claim 4, the magnetically conductive composite comprises a coil containing particles dispersed in a binder. Claim 14 In claim 13, the said particles comprise metallic particles, a coil. Claim 15 In claim 14, the metallic particles comprise an iron-aluminum-silicon alloy, forming a coil. Claim 16 In claim 1, one or more of the one or more second electrical insulating layers comprises an adhesive layer and a magnetic conductive layer disposed on the adhesive layer, forming a coil. Claim 17 In claim 1, the first electrically conductive layer is a magnetically insulative coil. Claim 18 In claim 1, the first electrically conductive layer comprises a coil including a metal. Claim 19 A coil comprising a multilayer film wound to form a plurality of substantially concentric loops, wherein the multilayer film comprises a plurality of first electrically conductive layers spaced apart from each other in the thickness direction; a second adhesive layer disposed between two or more adjacent first electrically conductive layers; and a third magnetically conductive layer, wherein one or more of the plurality of first electrically conductive layers are disposed on the third magnetically conductive layer, and the first electrically conductive layers, the second adhesive layer, and the third magnetically conductive layer have substantially coextensive widths and lengths such that each of the substantially planar main coil surfaces includes corresponding end surfaces of the first electrically conductive layer, the second adhesive layer, and the third magnetically conductive layer, and the two or more first electrically conductive layers have different average thicknesses that reduce the AC resistance of the coil by 3% or more and 6.6% or less at a frequency of 143 kHz or higher. Claim 20 A wireless charging system comprising a substantially planar coil comprising a plurality of concentric loops; and an electric circuit configured to be wirelessly charged by the wireless charging system, wherein each of the concentric loops comprises a metal layer substantially aligned with the loop, and the metal layers of two or more of the concentric loops have different average thicknesses that reduce the charging time by the wireless charging system by 3% or more and 6.6% or less at a frequency of 143 kHz or higher. Claim 21 A method for manufacturing a coil, comprising: providing a multilayer film comprising a plurality of alternating first electrically conductive layers; and one or more second electrically insulating layers; winding the multilayer film to form a multilayer film wound around a longitudinal axis, said multilayer film comprising a plurality of substantially concentric turns of said multilayer film centered substantially on a longitudinal axis; and cutting said multilayer film in a direction substantially perpendicular to said longitudinal axis to form a coil, said coil comprising a plurality of substantially concentric loops of said multilayer film, said loop comprising an innermost loop including a first longitudinal end of said coil and an outermost loop including a second longitudinal end of said coil, said coil comprising main coil surfaces that are opposite to each other and substantially flat. Claim 22 In claim 21, a method for manufacturing a coil in which the multilayer film is substantially wound around an elongated rod centered on the longitudinal axis. Claim 23 In claim 22, a method for manufacturing a coil, wherein the long rod comprises a substantially circular cross-section. Claim 24 A method for manufacturing a coil according to claim 22, wherein the long rod comprises a substantially polygonal cross-section.

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