TWM503641U - Multi-layer metal coil, inductor, transformer, wireless charger, relay - Google Patents

Description

Multi-layer metal coils, inductors, transformers, wireless chargers, relays

The present invention relates to a coil, and more particularly to a multilayer metal coil. The creation also relates to an inductor, transformer, wireless charger, and relay based on a multilayer metal coil.

Coils are generally used in electronic components. For example: the primary winding coil and the secondary winding coil of the transformer, the inductor coil of the inductor, the charging coil of the wireless charger, the AC-DC coil in the AC/DC motor, and the like. Among them, transformers, inductors, wireless chargers, AC motors, and DC motors are all electronic components. Such electronic components generally need to be soldered in printed circuit boards. At present, the coils in the prior art are generally wound by an insulated metal wire, for example, an enameled wire or a yarn wrapped wire; the metal wire is generally wound by a metal wire having a circular cross-sectional area, and the metal wire may be hollow. Can be solid. A coil wound with a metal wire having a circular cross-sectional area needs to be wound by a special coil winding machine. The disadvantage is that the wound coil has a relatively large inner diameter of the wound coil due to the limitation of the circular metal wire. Therefore, the volume of the coil after winding is large, and the space occupied by the soldering in the printed circuit board is large, which is not suitable for handheld electronic devices such as mobile phones, tablet computers, and handheld ID card number checking devices, and is not applicable to other required space occupancy rates. Small printed circuit board. In addition, the metal coil having a circular cross-sectional area is determined by the wire diameter, so that the cross-sectional area of the electrode pins of the metal coil is small, in order to increase the electrode pins. The cross-sectional area is adapted to the soldering requirements of the printed circuit board. Generally, it is necessary to separately solder a metal piece having a wide cross-sectional area on the pin of the coil to form an electrode pin having a large cross-sectional area, or to flatten the pin of the coil. In order to form electrode pins with a large cross-sectional area, the manufacturing process of the coil is complicated. In addition, when the metal coil of the above structure meets different requirements of the sensitivity parameter, it is generally required to replace the metal wire of different wire diameters, thereby making it difficult to adjust the inductance value of the coil.

The technical problem to be solved by the present invention is to provide a multi-layer metal coil which is simple in material production process, small in size, easy to adjust in sense value, and which does not require an additional electrode pin to save material.

In order to solve the above technical problem, the technical solution of the present invention is: a multilayer metal coil comprising a first metal coil and a second metal coil made of a flat metal sheet, the first metal coil and the second metal coil being covered with an insulating film layer The first metal coil and the second metal coil each include an integrally formed electrode pin, an air core coil and a connecting end. The electrode pin is located outside the air core coil, and the connecting end is located inside the air core coil or overlaps the above Above the air-core coil, the first metal coil and the second metal coil are superposed on each other, and the first metal coil and the hollow coil of the second metal coil are superposed to form a complete multilayer hollow coil, and the electrode of the first metal coil The pins are offset from the electrode pins of the second metal coil, and the connection end of the first metal coil is electrically connected to the connection end of the second metal coil, and the circuit connection is covered with an insulating film layer.

Further, in the multilayer metal coil of the above structure, the hollow coils of the first metal coil and the second metal coil are single-layer single-turn or single-layer multi-turn.

Further, the multilayer metal coil of the above structure, the first metal The air coil of the coil and the second metal coil is a single layer coil or a multilayer coil.

Further, in the multilayer metal coil of the above structure, the hollow coils of the first metal coil and the second metal coil are each a plurality of layers of a single turn or a plurality of layers.

Further, in the multilayer metal coil of the above structure, the hollow coil of the first metal coil and the second metal coil includes a single coil connected to the electrode pin, and a plurality of coils connected to the single coil, and the other end of the plurality of coils is the above At the connecting end, the single coil and the multi-coil are folded in opposite directions to form a multi-layer multi-turn hollow coil.

Further, in the multilayer metal coil of the above configuration, the folded position of the single coil and the multi-coil is provided with a folded notch.

Further, in the multilayer metal coil of the above structure, the hollow coil of the first metal coil and the second metal coil includes a plurality of coils formed by connecting a plurality of single coils, and one end of the plurality of coils is connected to the electrode pins, and the plurality of coils are The other end is the above-mentioned connecting end, and two adjacent single coils are folded in opposite directions to form a multi-layer single-turn hollow coil.

Further, in the multilayer metal coil of the above structure, the folded positions of the adjacent two single coils and the single coil are provided with folded notches.

Further, in the multilayer metal coil of the above structure, the multi-layer single-turn hollow coil is a multi-layer closed hollow coil formed by aligning the flat metal sheets distributed in a wave shape. Further, in the multilayer metal coil of the above structure, the shape of the multi-layer closed air-core coil is one of a circular shape, an elliptical shape, a rectangular shape, a triangular shape, a diamond shape, and a polygonal shape.

Further, in the multilayer metal coil of the above structure, the portion where the electrode pin is connected to the air-core coil is provided with a bent hole.

Further, the multilayer metal coil of the above structure, the insulating film layer It is an insulating tape layer, a coating layer, a printed layer or a powder electrostatic layer.

Further, in the multilayer metal coil of the above structure, the electrode pins of the first metal coil and the electrode pins of the second metal coil are arranged in line or at an angle or in parallel.

Further, in the multilayer metal coil of the above configuration, the circuit of the connection end of the first metal coil and the connection end of the second metal coil is soldered or riveted.

Further, in the multilayer metal coil of the above structure, the above welding is laser welding.

Further, in the multilayer metal coil of the above configuration, the riveting is a metal rivet riveting.

Further, in the multilayer metal coil of the above configuration, the electrode pins are covered with an insulating film layer at most at the position of the end face of the electrode pin along the position connected to the air-core coil.

Compared with the prior art, the present invention is a multilayer metal coil formed by superposing a first metal coil and a second metal coil on each other and electrically connecting the two connection ends. Since the first metal coil and the second metal coil are insulated by an insulating film layer, the coil and the coil are insulated, and an insulating film layer is also disposed at the circuit connection of the two connecting ends, so the first metal The layer and the layer of a multilayer metal coil formed by superposing the coil and the second metal coil are also insulated. In this creation, since the first metal coil and the second metal coil are made of metal sheets, the two metal coils are superposed and connected. Since the two metal coils are in the form of a sheet, the cross-sectional area is rectangular, and therefore, has a small volume. advantage. Compared with the metal wire with a circular cross-sectional area, in the case of the same volume, the multilayer metal coil of the present invention can increase the inductance value of the metal coil at the same sensitivity value. In the case, the volume can be made smaller, so material can also be saved. In addition, since the first metal coil and the second metal coil of the present invention are made of a flat metal piece, the thickness of the metal piece, the width of the formed coil, and the number of turns of the coil can be arbitrarily made, and it is not necessary to replace different wire diameters. The metal wire, therefore, the sense value of this creation is easier to adjust. The electrode pins of the multilayer metal coil of the present invention are integrally formed in the hollow coil portion. Therefore, electrode pins of different widths can be fabricated to suit the needs of the printed circuit board, and it is not necessary to separately add the electrode pins, so the multilayer metal of the present invention The coil making process is simple.

The present invention also provides an inductor comprising the multilayer metal coil of the above structure.

The present invention also provides a transformer comprising an iron core and at least one set of primary coils wound around the iron core and at least one set of secondary coils, the primary coil and the secondary coil being the multilayer metal coil of the above structure.

The present invention also provides a wireless charger including a wireless charging coil, and the wireless charging coil is a multilayer metal coil of the above structure.

The creation also provides a relay including a relay coil, which is a multilayer metal coil of the above structure.

The inductors, transformers, wireless chargers, and relays provided by the present invention all adopt the multi-layer metal coils of the above structure, so that the manufacturing process is simple, the volume is small, the sense value is easily adjusted, and the electrode pins are not separately added. Save the advantages of materials.

100‧‧‧Multilayer metal coil

110‧‧‧First metal coil

111‧‧‧First electrode pin

112‧‧‧First air-core coil

113‧‧‧First connection

114‧‧‧First insulating film

115‧‧‧First bend hole

116‧‧‧First folding gap

120‧‧‧Second metal coil

121‧‧‧Second electrode pin

122‧‧‧Second air core coil

123‧‧‧second connection

124‧‧‧Second insulation film

125‧‧‧Second bent hole

126‧‧‧second folding gap

1 to 3 are schematic structural views of a first embodiment of the present invention; and FIG. 4 is a schematic perspective view of the first embodiment of the present invention; 5 is a schematic view of the front view of the second embodiment of the present invention; FIG. 6 is a schematic view of the front view of the second embodiment of the present invention; FIG. FIG. 11 is a schematic structural view of the third embodiment of the present invention; FIG. 12 is a schematic structural view of the fourth embodiment of the present invention; FIG. Figure 16 is a schematic side view of the combination of the fourth embodiment of the present invention; Figure 17 is a schematic perspective view of the combination of the fourth embodiment of the present invention; FIG. 19 is a schematic structural view of a metal coil after folding according to the fifth embodiment of the present invention; and FIG. 20 is a schematic front view of the multilayer metal coil of the fifth embodiment of the present invention.

The creation is described in detail below with reference to the accompanying drawings:

<Example 1>

As shown in FIG. 1 to FIG. 4, the multilayer coil 100 of the first embodiment, also referred to as a multilayer metal coil 100, includes a first metal coil 110 and a second metal coil 120 made of a flat metal sheet, and the first metal coil 110. And the second metal coil 120 includes an integrally formed electrode pin, an air core coil and a connecting end. Referring to FIG. 3, the first metal coil 110 is composed of a first electrode pin 111, a first air core pin 112, and a first connection. The second metal coil 120 is composed of a second electrode pin 121, a second air core 122, and a second connecting end 123. The first air core 112 of the first metal coil 110 is covered with an insulating film layer 114. The second air-core coil 122 of the two-metal coil 120 is covered with an insulating film layer 124, preferably The electrode pins are covered with an insulating film layer at a position close to the end face of the electrode coil, and the electrode pins may be covered with an insulating film layer or partially covered with an insulating film layer. The insulating film layer; that is, the first electrode pin 111 is partially or entirely covered with the first insulating film layer 114, and the second electrode pin 121 is partially or entirely covered with the second insulating film layer 124. The electrode pin is located outside the air-core coil, the connecting end is located inside the air-core coil, and the first metal coil 110 and the second metal coil 120 are superposed on each other, wherein the first air-core coil 112 and the second air-core coil 122 The superimposed portion forms a complete multi-layered air-core coil, wherein the first electrode pin 111 and the second electrode pin 121 are offset from each other, wherein the first connection end 113 is electrically connected to the second connection end 123, and the circuit connection is covered. There is an insulating film layer. Wherein, all of the above insulating film layers may be an insulating tape layer, a coating layer, a printing layer or a powder electrostatic layer. The purpose is to achieve insulation between the coil and the coil of the formed multilayer metal coil and between the layers to prevent leakage current. Wherein, the circuit connection can be realized by soldering or laser welding or by metal rivet riveting, in order to electrically connect the first metal coil 110 and the second metal coil 120 into a complete multi-layer metal coil. The laser welding has non-contact welding, and has small thermal deformation of the welded first metal coil and the second metal coil, small solder joints, narrow weld bead, small focused spot, and high-precision positioning effect.

The present invention is a multilayer metal coil formed by superposing a first metal coil 110 and a second metal coil 120 on each other and electrically connecting the two connection ends. Since the first air-core coil 112 of the first metal coil 110 and the second air-core coil 122 of the second metal coil 120 are insulated by an insulating film layer, the coil and the coil are insulated, and the circuit at the two connection ends The connection layer is also provided with an insulating film layer, and therefore, a layer and a layer of a multilayer metal coil formed by superposing the first metal coil 110 and the second metal coil 120 are also insulated. This creation is due to the first metal coil 110 and the second made of metal sheets. The metal coil 120 is further connected to the two metal coils. Since the two metal coils are in the form of a sheet, the cross-sectional area is rectangular, and therefore, the volume is small. Compared with the metal wire with a circular cross-sectional area, in the case of the same volume, the multilayer metal coil of the present invention can increase the magnitude of the inductance of the multilayer metal coil, and the volume can be made under the same sensitivity value. It is smaller, so it can save material. In addition, since the first metal coil 110 and the second metal coil 120 of the present invention are made of a flat metal piece, the thickness of the metal piece, and the width of the formed coil and the number of turns or the number of turns of the coil can be arbitrarily adjusted without The metal wire of different wire diameters is replaced, so the sense value of the creation is easier to adjust and the production process is simpler. The electrode pins of the multilayer metal coil of the present invention are integrally formed in the hollow coil portion. Therefore, electrode pins of different widths can be fabricated to suit the needs of the printed circuit board, and it is not necessary to separately add the electrode pins, so the multilayer metal of the present invention The coil making process is simple.

Referring to FIG. 1 to FIG. 3, in the embodiment, the number of layers of the first metal coil 110 and the second metal coil 120 is a single layer, and the number of turns is one and a half, wherein a half circle of one half is greater than or Less than or equal to 1/2 turn. Referring to FIG. 4, the first metal coil 110 and the second metal coil 120 are connected to each other to form a multilayer metal coil of two layers and two turns. It should be noted that the number of turns of the first metal coil 110 and the second metal coil 120 is not limited to the above specific embodiment, and may be formed into a single turn, that is, one turn, then the first metal coil 110 and the second metal coil 120 are both It is a single-layer single-turn, and the circuit is connected to form a 2-layer single-turn multilayer metal coil. The first and second metal coils can be formed by stamping, chemical etching, laser cutting, electric discharge machining, fast and slow wire cutting or other effective processing methods. In the multilayer metal coil of the present embodiment, the first metal coil 110 and the second metal coil 120 are directly superposed and connected to each other without being folded, and leakage does not occur, so that the circuit characteristics are more stable.

In a preferred embodiment, in the present embodiment, the first metal coil 110 and the second metal coil 120 are formed into coils of the same specification to facilitate adjustment of the magnitude of the inductance of the formed multilayer metal coil. Wherein, the same specification means that the shape of the air-core coil is the same, the number of turns of the air-core coil is the same, the width of the air-core coil is the same, and the thickness of the air-core coil is the same, wherein the width refers to the width of the line of the coil; wherein the same thickness means the same The first metal coil 110 and the second metal coil 120 are made of a metal piece of a thickness. In order to meet the requirements of the use environment of the printed circuit board, the shape of the first air-core coil 112 and the second air-core coil 122 may be circular, elliptical, or may be one of a polygon such as a rectangle, a triangle, a diamond, a pentagon or the like.

As a preferred embodiment, the first electrode pin 111 of the first metal coil 110 and the second electrode pin 121 of the second metal coil 120 in the present embodiment may be arranged in the same straight line, or may be 0 to 180 degrees. The angles are set to, for example, 15 degrees, 30 degrees, 45 degrees, 90 degrees, 180 degrees, etc., and can also be set in parallel. Therefore, the two electrode pins of the present embodiment have strong flexibility, and the positional relationship and angle of the two electrode pins can be adaptively adjusted according to the use environment of the printed circuit board.

<Embodiment 2>

As shown in FIG. 5 to FIG. 7 , the second embodiment is improved on the basis of the first embodiment, and the difference is that the first electrode pin 111 of the second embodiment is connected to the first air core 112. A first bending hole 115 is provided, and a portion of the second electrode pin 121 connected to the second air core coil 122 is provided with a second bending hole 125. The bending hole in the second embodiment may be an elliptical hole, a circular hole or a polygonal hole such as a rectangular hole or a triangular hole. The bent hole is deducted from the electrode pin and the air core coil in the first and second metal coils. The area of the joint, thereby reducing the hardness of the connection between the electrode pin and the air-core coil, therefore, at the electrode When the pin is bent, the bending angle of the electrode pin can be easily bent by applying a small force, thereby adjusting the angle and positional relationship between the two electrode pins.

Referring to FIGS. 5-7, the first metal coil 110 and the second metal coil 120 of the second embodiment are electrically connected to form a multilayer metal coil of two layers and two turns.

<Example 3>

As shown in FIG. 8 to FIG. 11 , the third embodiment is improved on the basis of the second embodiment, and the difference is that the first metal coil 110 and the second metal coil 120 in the third embodiment are both formed at one time. The three-layer single layer, but not limited to three turns, can also be set to two circles, five rings, ten rings, etc. according to actual needs, and the circuit connects the first metal coil 110 and the second metal coil 120 to form two layers of three layers. The metal coil is. The first metal coil 110 and the second metal coil 120 may be formed by stamping, chemical etching, laser cutting, electric discharge machining, fast and slow wire cutting or other effective processing methods. The third embodiment has the advantages that the multi-turn air-core coil increases or decreases the number of turns of the coil of the air-core coil portion to enlarge or reduce the area of the air-core coil portion, so as to make the volume smaller when the coil inductance value is satisfied. Multi-layer metal coil.

<Embodiment 4>

As shown in FIG. 12 to FIG. 17, the fourth embodiment is improved on the basis of the third embodiment, and the difference is that the hollow coil of the first metal coil 110 and the hollow of the second metal coil 120 in the fourth embodiment are hollow. The coils are multi-turn multilayer. Referring to FIGS. 12, 13, and 14, the plurality of turns of the air-core coil includes a single coil connected to the electrode pin, and a multi-coil connected to the single coil. The number of turns of the multi-coil is 3 turns, and the connection end is multi-coil One end. Referring to Figures 12 to 16, after the single coil is folded in alignment with the multi-coil of 3 turns, the single coil is overlapped with the multi-coil The outer ring, after folding, the first metal coil 110 and the second metal coil 120 are two layers, wherein one layer is a single coil, and the other layer is a multi-coil. After the circuit is connected, a four-layer three-turn multilayer metal coil is formed. The upper and lower layers are single coils, and the middle two layers are multi-coils. The number of layers and the number of turns in the fourth embodiment are not limited to four layers and three circles in the specific embodiment, and the number of layers and the number of turns can be set according to actual use environment requirements. The fourth embodiment has the advantages that on the one hand, it is convenient to increase or decrease the number of turns of the multi-coil in the air-core coil to enlarge or reduce the area of the air-core coil portion, so as to make the volume smaller when the coil inductance value is satisfied. Multi-layer metal coil; on the other hand, the air-core coil is integrally formed by a single coil and a multi-coil, so that the production of the air-core coil is more material-saving.

As shown in FIG. 13 and FIG. 14 , as a preferred embodiment, the folded position of the single coil and the multi-coil is provided with a folded notch, that is, the first metal coil 110 is provided with a first folded notch 116, and the second metal coil 120 is disposed. A second folded notch 126 is provided, such as the elliptical dotted frame position in FIG. Wherein, the folded notch may be an arc shape, or may be a rectangular shape or a semicircular shape or an elliptical shape. Its function is to make the alignment of the single coil and the multi-coil easier and convenient. Among them, the folded notch of the curved or elliptical or semi-circular shape has electrical characteristics that make the current flow more easily.

<Embodiment 5>

Referring to FIG. 18 to FIG. 20, the fifth embodiment is improved on the basis of the fourth embodiment. The difference is that the air-core coils of the first metal coil 110 and the second metal coil 120 are formed by connecting a plurality of single coils. a plurality of coils, one end of the plurality of coils is connected to the electrode pins, and the other end of the plurality of coils is the connecting end, and the adjacent two single coils are folded in opposite directions to form a multi-layer single-turn hollow coil, and the hollow coil portions are superposed Fully coincident, the first connecting end 113 and the second connecting end 123 are also respectively overlapped on the air-core coil.

In a preferred embodiment, the folded positions of the adjacent two single coils and the single coil are provided with folded notches. Wherein, the folded notch may be an arc shape, or may be a rectangular shape or a semicircular shape or an elliptical shape. Its function is to make the alignment of the single coil and the multi-coil easier and convenient. Among them, the folded notch of the curved or elliptical or semi-circular shape has electrical characteristics that make the current flow more easily.

As a preferred embodiment, in the fifth embodiment, the first metal coil 110 and the second metal coil 120 are two single coils, and after folding, form two layers of single turns, and the first metal coil 110 and the second metal coil 120 are electrically connected. After connection, a four-layer single-turn multilayer metal coil is formed. The layer of the multi-layer air-core coil of the fifth embodiment is superposed on the layer and overlaps the layer, and is not exposed on the inner side or the outer side of the air-core coil. The multi-layer metal coil of the structure is suitable for making an inductor, a transformer and a relay, and is particularly suitable for manufacturing. Encapsulated housing or inductor with a core such as a carbon rod.

As a preferred embodiment, in the fifth embodiment, the number of turns of the air-core coil of the first metal coil 110 and the number of turns of the air-core coil of the second metal coil 120 may be the same or different, so as to facilitate the adjustment. The value size.

<Embodiment 6>

The sixth embodiment is improved on the basis of the third embodiment, and the difference is that the multilayer hollow coil of the first metal coil 110 and the second metal coil 120 in the sixth embodiment is a flat metal distributed in a wave shape. A multi-layer closed hollow coil formed by folding the sheets in opposite directions. The wave shape is one of a sine wave, a square wave, and a triangular wave. Wherein, the shape of the multi-layer closed air-core coil may be one of a circle, an ellipse, a rectangle, a triangle, a diamond, and a polygon. The multilayer metal coil of such a structure, compared with the metal wire having a circular cross-sectional area, in the case of the same volume, the multilayer metal wire of the present invention The circle can increase the sense value of the multi-layer metal coil, and the volume can be made smaller under the same sense value, so that the material can be saved.

<Embodiment 7>

The seventh embodiment provides an inductor comprising the multilayer metal coils of the first to sixth embodiments. The two electrode pins of the multilayer metal coil are provided with a tin layer, a gold plating layer or a silver plating layer. Further included is a housing that covers the multilayered air-core coil of the plurality of metal coils, at least a portion of which is exposed outside the housing.

<Embodiment 8>

The eighth embodiment provides a transformer including a core and at least one set of primary coils and at least one set of secondary coils wound on the core, wherein the primary coil and the secondary coil are the multilayer metal coils of Embodiments 1 to 6.

<Example 9>

The ninth embodiment provides a wireless charger including a wireless charging coil, and the wireless charging coil uses the above-mentioned multilayer metal coil in the first to sixth embodiments.

<Example 10>

The tenth embodiment provides a relay including a relay coil, which is a multilayer metal coil according to any one of claims 1 to 13.

The inductors, transformers, wireless chargers, and relays provided by the present invention all adopt the multi-layer metal coils of the above structure, so that the manufacturing process is simple, the volume is small, the sense value is easily adjusted, and the electrode pins are not separately added. Saving material The advantages of the material.

The present invention is not limited to the specific embodiments described above, and all changes made within the spirit and scope of the present patent application scope are within the protection scope of the present invention.

100‧‧‧Multilayer metal coil

110‧‧‧First metal coil

120‧‧‧Second metal coil

Claims (20)

A multi-layer metal coil, comprising: a first metal coil and a second metal coil made of a flat metal piece, wherein the first metal coil and the second metal coil each comprise an integrally formed electrode pin, an air core coil and a connecting end The hollow coil is covered with an insulating film layer, the electrode pin is located outside the hollow coil, and the connecting end is located inside the hollow coil or overlaps the hollow coil, and the first metal coil and the second metal coil Superimposing each other, the first metal coil and the hollow coil superimposed portion of the second metal coil form a complete multilayer hollow coil, and the electrode pins of the first metal coil and the electrode pins of the second metal coil are mutually offset, The connection end of the first metal coil is electrically connected to the connection end of the second metal coil, and the circuit connection is covered with an insulating film layer. The multilayer metal coil of claim 1, wherein the hollow coils of the first metal coil and the second metal coil are single-layer single-turn or single-layer multi-turn. The multilayer metal coil of claim 1, wherein the hollow coils of the first metal coil and the second metal coil are each a plurality of layers of single or multiple layers. The multilayer metal coil of claim 3, wherein the hollow coil of the first metal coil and the second metal coil comprises a single coil connected to the electrode pin, and a plurality of coils connected to the single coil, the multi-coil The other end is the connecting end, and the single coil and the multi-coil are folded in opposite directions to form a multi-layer multi-turn hollow coil. The multi-layer metal coil of claim 4, wherein the folded position of the single coil and the multi-coil is provided with a folded notch. The multi-layer metal coil of claim 1, wherein the first metal coil and the second metal coil air-core coil comprise a plurality of coils formed by connecting a plurality of single coils, one end of the plurality of coils being connected to the electrode pins, Another of the above multiple coils The end is the above connecting end, and the adjacent two single coils are folded in the opposite direction to form a multi-layer single-turn hollow coil. The multi-layer metal coil of claim 6, wherein the folded positions of the adjacent two single coils and the single coil are provided with folded notches. The multi-layer metal coil of claim 3, wherein the multi-layer single-turn hollow coil is a multi-layer closed hollow coil formed by aligning flat metal sheets distributed in a wave shape. The multilayer metal coil of claim 1, wherein the hollow coil has a shape of one of a circle, an ellipse, a rectangle, a triangle, and a diamond. The multi-layer metal coil of claim 1, wherein the portion where the electrode pin is connected to the air-core coil is provided with a bent hole. The multilayer metal coil of claim 1, wherein the insulating film layer is an insulating tape layer, a coating layer, a printed layer or a powder electrostatic layer. The multi-layer metal coil of claim 1, wherein the electrode pins of the first metal coil and the electrode pins of the second metal coil are disposed in line or at an angle or in a row. The multilayer metal coil of claim 1, wherein the connecting end of the first metal coil and the connecting end of the second metal coil are soldered or riveted. The multilayer metal coil of claim 13, wherein the welding is laser welding. The multilayer metal coil of claim 13, wherein the riveting is a metal rivet riveting. The multilayer metal coil of claim 1, wherein the electrode is connected The foot is covered with an insulating film layer at most to the end face position of the electrode pin at a position where it is connected to the above-mentioned air-core coil. An inductor comprising a multilayer metal coil according to any one of claims 1 to 16. A transformer comprising: an iron core; and at least one set of primary coils and at least one set of secondary coils wound on the iron core, wherein the primary coil and the secondary coil are both in the scope of claims 1 to 16. A multi-layer metal coil. A wireless charger comprising a wireless charging coil, the wireless charging coil being a multilayer metal coil according to any one of claims 1 to 16. A relay comprising a relay coil, the relay coil being a multilayer metal coil according to any one of claims 1 to 16.