Charging coil and preparation method thereof

Abstract

The invention relates to the technical field of preparation of copper coils, in particular to a preparation method of a charging coil, which comprises the following steps of: (1) ablating a spiral winding image I on one surface of a copper foil, so that an ablated wire slot I is formed on the copper foil, and the thickness of the ablated wire slot I is more than 1 / 2 of the thickness of the copper foil and less than the thickness of the copper foil; (2) attaching an insulating material to one surface of the copper foil, which contains the first ablation wire slot, so as to form an insulating layer; and (3) a second spiral winding image is ablated on the other face of the copper foil, a second ablated wire groove is formed in the copper foil, the charging coil is obtained, the sum of the thickness of the first ablated wire groove and the thickness of the second ablated wire groove is the same as the thickness of the copper foil, and the first spiral winding image corresponds to the second spiral winding image. According to the method, the thin metal is cut in a double-sided ablation mode, so that the copper coil with fine line width and line distance can be conveniently obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of charging coil preparation, and in particular to a charging coil and a preparation method thereof. Background Art

[0002] In recent years, with the continuous advancement of wireless charging standardization, charging efficiency and convenience have been continuously improved, and the demand for wireless charging market has increased. In particular, wireless charging has gradually become a standard feature of mid-to-high-end mobile phones, and consumer electronic products such as TWS headphones, smart watches, and tablets have begun to be equipped with wireless charging. Combined with the current "smart home" lifestyle trend, the future will also stimulate wireless charging technology to penetrate into more consumer mobile electronic products, such as automobiles, smart homes, and medical equipment, and will eventually form a wide range of application scenarios.

[0003] Wireless charging technology is a way of transmitting energy wirelessly, transferring electrical energy from a transmitter to a receiver to charge a device. Wireless charging technology mainly includes the following methods: electromagnetic induction, magnetic resonance, and electric field coupling. Among them, magnetic resonance, electric field coupling or electromagnetic induction coils, as core components of wireless charging, have an important impact on the power and efficiency of wireless charging. In order to achieve higher wireless charging power, the impedance of the coil must be reduced. The general practice is to increase the thickness of the conductive layer or select materials with high conductivity to achieve this. However, increasing the thickness goes against the pursuit of thinness and smallness of electronic products, and materials with high conductivity are bound to increase the cost of the product, which is not conducive to the promotion of the product.

[0004] The manufacturing methods of wireless charging coils include circuit board etching and copper wire winding. For materials with a copper thickness of more than 70 microns, the T-shaped phenomenon of the circuit board etching coil is serious (wide at the top and narrow at the bottom), the spacing is wide (more than 120 microns), the performance is degraded, and the production capacity is low and the cost is high; among them, when multiple strands of copper wire are used to wind the coil in parallel, when the thickness of the copper wire is less than 80μm, the processing efficiency and yield rate of the copper winding drop sharply, and the cost rises sharply, which is not conducive to the thinning development trend of the product; there are many problems when using laser to cut thin metals (thickness less than 1mm), especially coil cutting for electromagnetic induction (thin lines, narrow spacing). If a copper coil is obtained by laser cutting copper foil (more than 80μm), the following difficulties will be encountered:

[0005] 1) During the laser cutting process of copper foil, the energy emitted by the laser is absorbed by the copper foil. The high heat generated instantly causes the copper foil to be severely deformed locally, and the size of the cutting position has obvious deviations, making it impossible to achieve fine line segmentation.

[0006] 2) Because the thickness of the copper foil is too small relative to the width of the line, the internal stress of the material is too large when the laser light is focused and cut, which easily produces a spring effect, directly affecting the shape of the copper coil and the accuracy of the line width and spacing.

[0007] Chinese patent CN 208961261 U discloses a copper coil structure, in which a connecting bridge and a groove are provided on thick copper with a thickness of more than 100 μm; the connecting bridge is located on the thick copper and has a certain width, and the connecting bridge refers to a specific block on the thick copper that is not cut through by the laser beam; the groove is arranged on both sides of the connecting bridge and presents an arc-shaped appearance, and the groove is formed by laser cutting. When the above method is used to cut copper foil to prepare a copper coil with a larger line width, due to the large internal stress during focused cutting, a spring effect is easily generated, which affects the shape of the copper coil and the line width and line spacing accuracy.

[0008] Therefore, there is an urgent need to provide a method for cutting copper foil with higher precision to prepare copper coils. Summary of the invention

[0009] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a charging coil and a method for preparing the same, so as to solve the problem of low precision of the method for cutting copper foil to prepare the charging coil in the prior art.

[0010] To achieve the above objectives and other related objectives, the present invention is achieved through the following technical solutions.

[0011] A first aspect of the present invention is to provide a method for preparing a charging coil, the method comprising the following steps:

[0012] (1) ablation of a spiral winding image 1 on one side of the copper foil, so that ablation groove 1 is formed on the copper foil, wherein the thickness of the ablation groove 1 exceeds 1 / 2 of the thickness of the copper foil and is less than the thickness of the copper foil;

[0013] (2) Laminating the insulating material to the side of the copper foil containing the ablated wire groove to form an insulating layer;

[0014] (3) A second spiral winding image is ablated on the other side of the copper foil, so that a second ablation groove is formed on the copper foil to obtain a charging coil, wherein the sum of the thickness of the first ablation groove and the second ablation groove is the same as the thickness of the copper foil, and the first spiral winding image and the second spiral winding image correspond to each other.

[0015] A second aspect of the present invention is to provide a charging coil, which is manufactured using the above-mentioned manufacturing method.

[0016] As described above, a charging coil and a preparation method thereof of the present invention have the following beneficial effects:

[0017] (1) The preparation method of the charging coil of the present invention is to cut thin metal by double-sided ablation, which is convenient for reducing the internal stress of the material during focused ablation, reducing the generation of spring effect, and facilitating obtaining a copper coil with fine line width and line spacing.

[0018] (2) The present invention attaches a single-sided ablated thin metal to an insulating material and then ablates the reverse side, thereby effectively reducing the problems of copper warping, deformation, and circuit structure displacement due to heat, reducing the impact on the cutting accuracy, and obtaining a precise image.

[0019] (3) The process of the present invention is simple, low-cost, and convenient for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Shown is a schematic cross-sectional view of the spiral winding of the charging coil of the present invention.

[0021] Figure 2 Shown is a schematic diagram of a charging coil made according to Example 1 of the present invention.

[0022] Figure 3 Shown is a schematic diagram of a charging coil made according to Example 2 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose of the invention, technical solutions and beneficial technical effects of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. People familiar with this technology can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0024] A first aspect of the present invention is to provide a method for preparing a charging coil, the method comprising the following steps:

[0025] (1) ablation of a spiral winding image 1 on one side of the copper foil, so that ablation groove 1 is formed on the copper foil, wherein the thickness of the ablation groove 1 exceeds 1 / 2 of the thickness of the copper foil and is less than the thickness of the copper foil;

[0026] (2) Laminating the insulating material to the side of the copper foil containing the ablated wire groove to form an insulating layer;

[0027] (3) A second spiral winding image is ablated on the other side of the copper foil, so that a second ablation groove is formed on the copper foil to obtain a charging coil, wherein the thickness of the first ablation groove and the second ablation groove is the same as the thickness of the copper foil, and the first spiral winding image and the second spiral winding image correspond to each other.

[0028] The present invention forms a specific functional structure by cutting a thin metal through double-sided ablation, so that the metal presents a thick copper coil with a U-shaped cross section. The first ablation does not penetrate, and the second ablation penetrates the entire metal, thereby obtaining a copper coil, which is convenient for reducing the heat dissipation of ablation, thereby reducing the influence of ablation on the accuracy of the copper coil. The provision of an insulating layer is convenient for reducing the spring effect caused by the small thickness of the copper foil relative to the width of the line, thereby reducing the influence of ablation on the shape of the copper coil and the accuracy of the line width and line spacing.

[0029] In some embodiments of the present invention, the thickness of the ablated wire groove 1 in step (1) exceeds 1 / 2 of the thickness of the copper foil and is less than the thickness of the copper foil.

[0030] In some embodiments of the present invention, the two sides of the copper foil in step (1) are respectively roughened and then ablated; preferably, the roughening treatment is selected from any one of browning treatment, plasma treatment, and sandblasting treatment; further preferably, the roughening treatment is browning treatment. The present invention does not specifically limit the conditions for the browning treatment, and the browning treatment conditions commonly used in the art can be used. Roughening the two planes of the copper foil that need to be ablated later is beneficial to absorb laser energy during laser processing, reduce energy reflection, improve heat aggregation, and thus improve the accuracy of the copper coil obtained.

[0031] In some embodiments of the present invention, the ablation method in step (1) is selected from any one of laser ablation and plasma ablation; preferably, the cutting method is laser ablation. The present invention has no particular restrictions on the laser conditions of laser ablation, as long as the purpose of ablation can be achieved, and the specific laser parameter settings are adjusted according to the wavelength of the laser and the laser emitting device. Specifically, the laser ablation is to place the copper foil in the corresponding tooling for positioning and laser ablation processing. The excellent beam quality emitted by the laser (typical focal diameter is 10 to 50 μm) can produce a huge power density on the copper foil, so that the copper foil is instantly heated to the vaporization temperature and evaporated to form holes; at the same time, according to the pre-programmed graphics, the computer numerical control system is used to control the movement of the beam to the copper foil material, and the holes continuously form extremely narrow gaps, completing the ablation of the copper foil, and obtaining a pre-programmed copper foil graphic, that is, a spiral winding image one. In some embodiments of the present invention, the thickness of the copper foil is 0.02-1.0 mm. Specifically, the thickness of the copper foil can be 0.02-0.08mm, 0.08-0.2mm, 0.2-0.6mm, 0.6-0.8mm, 0.8-1mm; typically but not limiting, for example, 0.02mm, 0.08mm, 0.2mm, 0.6mm, 0.8mm, 1mm. The present invention has no special limitation on the source of the copper foil, and the copper foil commonly used by those skilled in the art can be used. The thickness of the copper foil required to be cut in the present invention is relatively thin, so it is not easy to have the phenomenon of thermal offset during the cutting process, and it is easier to cut quickly and mass produce.

[0032] In some embodiments of the present invention, the spiral winding image 1 in step (1) is selected from any one of a ring-shaped spiral winding image, a rectangular spiral winding image, and a special-shaped spiral winding image. The shape of the spiral winding image 1 of the present invention is not particularly limited and can be designed according to the actual required functions. The spiral winding image 1 is designed according to a program.

[0033] In some embodiments of the present invention, the thickness of the insulating layer in step (2) is 0.005-0.5 mm. Specifically, the thickness of the insulating layer can be 0.005-0.01 mm, 0.01-0.2 mm, 0.2-0.5 mm; typically but not limiting, for example, 0.005 mm, 0.01 mm, 0.2 mm, 0.5 mm.

[0034] In some embodiments of the present invention, the bonding method in step (2) is selected from bonding or hot pressing.

[0035] In some embodiments of the present invention, the bonding method in step (2) is bonding. The bonding agent used is an insulating glue; preferably, the insulating glue is selected from any one of epoxy resin glue, acrylic glue, polyimide glue, polyurethane glue, and hydrocarbon resin glue. The present invention has no special restrictions on the source of the selected insulating glue, and the insulating glue commonly used by those skilled in the art can be used. The present invention has no special restrictions on the bonding conditions used in bonding, as long as the purpose of bonding can be achieved.

[0036] In some embodiments of the present invention, the insulating material in step (2) is selected from a prepreg or a soft board substrate. The selection of the prepreg is not limited to PP sheets and resin sheets, and can be selected according to experimental requirements; the soft board substrate is selected from any one of polyimide, polyethylene terephthalate and liquid crystal polymer. The present invention has no special restrictions on the source of the selected soft board substrate, and the soft board substrate commonly used in the art can be used. The present invention has no special restrictions on the source of the selected prepreg, and the prepreg commonly used in the art can be used.

[0037] In some embodiments of the present invention, the line pitch of the charging coil in step (3) is 0.01-0.15 mm; specifically, the line pitch of the charging coil is 0.01-0.06 mm, 0.06-0.1 mm, 0.1-0.15 mm. Typical but non-limiting examples include 0.01 mm, 0.015 mm, 0.06 mm, 0.1 mm, and 0.15 mm.

[0038] In some embodiments of the present invention, the line width of the charging coil in step (3) is 0.1-1 mm. Specifically, the line width of the charging coil may be 0.1-0.2 mm, 0.2-0.3 mm, 0.3-0.5 mm, 0.5-0.8 mm, 0.8-1 mm, typically but not limiting, for example, 0.1 mm, 0.2 mm, 0.3 mm, 0.5 mm, 0.8 mm, 1 mm.

[0039] In some embodiments of the present invention, the cross-section of the spiral winding in the charging coil is in the shape of a letter "Y". The cross-section of the spiral winding in the charging coil is in the shape of a letter "Y" by double-sided laser ablation. Figure 1 As shown, this is mainly because the laser beam is conical, similar to a horn shape, like a conical knife, so the cross-section of the spiral winding in the charging coil after double-sided cutting is in the shape of a sub-letter.

[0040] A second aspect of the present invention is to provide a charging coil, which is manufactured using the above-mentioned manufacturing method.

[0041] In some embodiments of the present invention, the line pitch of the charging coil is 0.01-0.15mm; the line width is 0.1-1.0mm; preferably, the line pitch of the charging coil is 0.015-0.06mm; the line width is 0.2-0.5mm. The line pitch and line width of the charging coil of the present application are not limited to the above description and can be adjusted according to actual process requirements.

[0042] The present invention is further described below by way of examples, but the scope of the present invention is not limited thereto.

[0043] When the embodiment gives a numerical range, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art. If specific conditions are not specified in the embodiment, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for all reagents or instruments, they are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, according to the grasp of the prior art by those skilled in the art and the record of the present invention, any method, equipment, and material of the prior art similar or equivalent to the method, equipment, and material in the embodiments of the present invention can also be used to realize the present invention.

[0044] Example

[0045] Example 1

[0046] The method for preparing the charging coil of this embodiment includes the following steps:

[0047] (1) placing a copper foil on an operating table, and then ablating a spiral winding pattern one designed according to a program on one side of the copper foil, so that an ablation groove one is formed on the copper foil; the thickness of the copper foil is 100 μm; the depth of the ablation groove one is 60 μm; the copper foil is a rolled copper foil; the ablation method is laser ablation, and the surface of the copper foil is browned;

[0048] (2) hot pressing a PI film with adhesive on one side onto the side of the copper foil containing the ablated wire groove to form an insulating layer; the thickness of the insulating layer is 50 μm; the hot pressing temperature is 200° C.; the hot pressing time is 150 min; the hot pressing pressure is 50 kg / cm 2 ; The manufacturer of the PI film with adhesive is DuPont Chemical;

[0049] (3) A second spiral winding image is ablated on the other side of the copper foil, so that a second ablation groove is formed on the copper foil to obtain a charging coil, wherein the sum of the thickness of the first ablation groove and the second ablation groove is the same as the thickness of the copper foil, and the first spiral winding image and the second spiral winding image correspond to each other and just ablate the copper foil. The schematic diagram of the copper coil is shown in FIG. Figure 2 shown.

[0050] Example 2

[0051] The method for preparing the charging coil of this embodiment includes the following steps:

[0052] (1) placing a copper foil on an operating table, and then ablating a spiral winding pattern one designed according to a program on one side of the copper foil, so that an ablation groove one is formed on the copper foil; the thickness of the copper foil is 120 μm; the depth of the ablation groove one is 80 μm; the copper foil is a rolled copper foil; and the ablation method is laser ablation;

[0053] (2) The epoxy prepreg is hot-pressed and laminated to the side of the copper foil containing the ablated wire groove to form an insulating layer, thereby obtaining a second copper foil; the thickness of the insulating layer is 100 μm; the temperature of the hot pressing is 200° C.; the time of the hot pressing is 150 min; the pressure of the hot pressing is 50 kg / cm 2 ; The epoxy prepreg manufacturer is Guangdong Shengyi Technology Co., Ltd.;

[0054] (3) A second spiral winding image is ablated on the other side of the copper foil, so that a second ablation groove is formed on the copper foil to obtain a charging coil, wherein the sum of the thickness of the first ablation groove and the second ablation groove is the same as the thickness of the copper foil, and the first spiral winding image and the second spiral winding image correspond to each other and just ablate the copper foil. The schematic diagram of the copper coil is shown in FIG. Figure 3 shown.

[0055] Comparative Example

[0056] Comparative Example 1

[0057] The preparation method of the charging coil of this comparative example is different from that of Example 1 in that the copper foil is etched by chemical solution to prepare the required copper coil. Specifically, the method comprises the following steps:

[0058] A flexible film is attached to one surface of the copper foil, and then a photosensitive glue is applied to the side of the copper foil facing away from the flexible film, and exposed using a UV laser. The exposed material is placed in a developer for development, exposing the copper surface of the non-coil part. The developed material is placed in an etching solution for corrosion. After the corrosion is completed, the remaining photosensitive film is removed in a film removal solution, and the line width of the copper coil is 100μm; the line spacing is 120μm. The thickness of the copper foil is 100μm. Among them, the flexible film is a PI material film.

[0059] Table 1 Performance test results of copper coils in Example 1 and Comparative Example 1

[0060] serial number Example 1 Comparative Example 1 Line width / line spacing (μm) 198 / 22 100 / 120 Ls(μH) 4.3 4.5 Rs(mΩ) 240 460 Rdc(mΩ) 212 380 Q 11.3 6.1

[0061] Test conditions: 1V100KHz AC electric field. Where Ls is AC inductance, Rs is AC resistance, Rdc is DC resistance, and Q is the quality factor of the coil.

[0062] The copper coil manufactured by the method of the present invention has a high copper content, and under the condition of the same inductance value, the quality factor of the coil is higher and the resistance value is smaller under the alternating current electric field.

[0063] Comparative Example 2

[0064] The preparation method of the charging coil of this comparative example is different from that of Example 2 in that: a chemical solution is used to etch the copper foil to prepare the required copper coil. A flexible film is attached to one surface of the copper foil, and then a photosensitive glue is coated on the side of the copper foil away from the flexible film, and a UV laser is used for exposure. The exposed material is placed in a developer for development to expose the copper surface of the non-coil part. The developed material is placed in an etching solution for corrosion. After the corrosion is completed, the remaining photosensitive film is removed by placing it in a film removal solution to obtain a copper coil with a line width of 380μm and a line spacing of 150μm. The thickness of the copper foil is 120μm. Among them, the flexible film is a PI material film with a backing adhesive.

[0065] Table 2 is the performance test results of the copper coils of Example 2 and Comparative Example 2

[0066] serial number Example 2 Comparative Example 2 Line width / line spacing (μm) 495 / 35 380 / 150 Ls(μH) 5.8 5.9 Rs(mΩ) 220 305 Rdc(mΩ) 190 260 Q 16.5 11.2

[0067] Test conditions: 1V100KHz AC electric field. Ls is AC inductance, Rs is AC resistance, Rdc is DC resistance, and Q is the quality factor of the coil.

[0068] The copper coil manufactured by the method of the present invention has a high copper content, and under the condition of the same inductance value, the quality factor of the coil is higher and the resistance value is smaller under the alternating current electric field.

[0069] The copper coil manufactured by the method of the present invention has high precision, large line width and small line spacing.

[0070] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing a charging coil, characterized in that: The preparation method comprises the following steps: (1) ablation of a spiral winding image 1 on one side of the copper foil, so that ablation groove 1 is formed on the copper foil, wherein the thickness of the ablation groove 1 exceeds 1 / 2 of the thickness of the copper foil and is less than the thickness of the copper foil; (2) Laminating the insulating material to the side of the copper foil containing the ablated wire groove to form an insulating layer; (3) A second spiral winding image is ablated on the other side of the copper foil, so that a second ablation groove is formed on the copper foil to obtain a charging coil, wherein the sum of the thickness of the first ablation groove and the second ablation groove is the same as the thickness of the copper foil, and the first spiral winding image and the second spiral winding image correspond to each other.

2. The method for preparing a charging coil according to claim 1, characterized in that: The step (1) also includes one or more of the following features: 11) The two sides of the copper foil are respectively roughened and then ablated; 12) The ablation method is selected from any one of laser ablation and plasma ablation; 13) The thickness of the copper foil is 0.02-1.0 mm; 14) The spiral winding image is selected from any one of a ring-shaped spiral winding image, a rectangular spiral winding image, and a special-shaped spiral winding image; 15) The copper foil is selected from any one of rolled copper foil, electrolytic copper foil and composite copper foil.

3. The method for preparing a charging coil according to claim 2, characterized in that: Also includes one or more of the following characteristics: 111) The roughening treatment is selected from any one of browning treatment, plasma treatment and sandblasting treatment; 121) The ablation method is laser ablation.

4. The method for preparing a charging coil according to claim 1, characterized in that: The step (2) also includes one or more of the following features: 21) The thickness of the insulating layer is 0.005-0.5 mm; 22) The bonding method is selected from bonding or hot pressing; 23) The insulating material is selected from a prepreg or a soft board substrate.

5. The method for preparing a charging coil according to claim 4, characterized in that: Also includes one or more of the following characteristics: 221) The adhesive used for bonding is insulating glue; preferably, the insulating glue is selected from any one of epoxy resin glue, acrylic glue, polyimide glue, polyurethane glue, and hydrocarbon resin glue; 231) The soft board substrate is selected from any one of polyimide, polyethylene terephthalate and liquid crystal polymer.

6. The method for preparing a charging coil according to claim 1, characterized in that: The step (3) also includes one or more of the following features: 31) In step (3), the wire spacing of the charging coil is 0.01-0.15 mm; 32) In step (3), the line width of the charging coil is 0.1-1 mm.

7. The method for preparing a charging coil according to claim 6, characterized in that: Also includes one or more of the following characteristics: 311) The wire spacing of the charging coil is 0.02-0.08mm; 321) The line width of the charging coil is 0.2-0.8mm.

8. The method for preparing a charging coil according to claim 1, characterized in that: The cross-section of the spiral winding in the charging coil is in the shape of a letter "Y".

9. A charging coil, characterized in that: The method is prepared by any one of claims 1 to 8.

10. A charging coil according to claim 9, characterized in that: The line pitch of the charging coil is 0.01-0.15mm; the line width is 0.1-1.0mm; preferably, the line pitch of the charging coil is 0.02-0.08mm; the line width is 0.2-0.8mm.

Images