Preparation method of wireless charging coil and wireless charger

Abstract

The application relates to a preparation method of a wireless charging coil, and the preparation process comprises the following steps: preparing a medium magnetic powder slurry, preparing a ferrite medium film piece, preparing a Ba block film piece, providing an electrode slurry, preparing an insulating ferrite slurry, carrying out a silk screen printing treatment, carrying out a laminating treatment, carrying out a glue removal sintering treatment, and preparing the wireless charging coil. The preparation method of the wireless charging coil provided by the application integrates the magnetic piece, the electrode and the insulating magnetic material through sintering, so that the electrode and the magnetic piece can be tightly connected without gap loss, the power conversion efficiency, the current resistance characteristic and the transmitting power are improved, the product performance and the heat dissipation effect are improved, the wireless charger manufactured through the preparation method does not generate waste water and other pollution problems in the production process, and the wireless charger has the characteristics of energy saving and environmental protection.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless charging, and in particular relates to a method for preparing a wireless charging coil and a wireless charger. Background Art

[0002] With the rapid development of electronic information technology, electronic products have occupied an irreplaceable and important position in people's lives. Wireless charging technology, with its convenience, compatibility and non-contact nature, reduces plug-in and unplugging problems, avoids problems such as poor contact and inappropriate interfaces, and multiple receiving devices can be charged on the same wireless charging device, solving the problem of wireless charging devices being restricted by lines and realizing the complete separation of power supply and electrical appliances. Compared with traditional chargers, it has the advantages of flexibility and safety.

[0003] However, traditional methods for preparing wireless charging coils have the following disadvantages: 1. Low production efficiency, requiring separate coil preparation; 2. High manufacturing costs, as polishing the magnetic sheet produces polluted water; and 3. The motor coil is attached to the magnetic sheet, resulting in a gap between the electrode coil and the magnetic sheet, which increases power loss and reduces power conversion efficiency.

[0004] Therefore, the present invention provides a method for preparing a wireless charging coil and a wireless charger to solve the above technical problems. Summary of the Invention

[0005] In view of the above problems, the object of the present invention is to provide a method for preparing a wireless charging coil and a wireless charger, which have no gap power loss, high power conversion efficiency, and are energy-saving and environmentally friendly.

[0006] The present invention provides a method for preparing a wireless charging coil, comprising the following steps:

[0007] S1, preparing a dielectric magnetic powder slurry: providing a grinding ball unit, a first ferrite magnetic powder, and a first solvent, and mixing the grinding ball unit, the first ferrite magnetic powder, and the first solvent in a preset ratio to form a first mixture; adding an appropriate amount of a plasticizer, a dispersant, and a defoaming agent to the first mixture to form a second mixture; ball milling or sand milling the second mixture, and adding a binder resin to the ball-milled or sand-milled second mixture to form a third mixture; ball milling or sand milling the third mixture to form a first slurry, and performing a first pretreatment on the first slurry to form a dielectric magnetic powder slurry;

[0008] S2, preparing a ferrite dielectric diaphragm: placing the dielectric magnetic powder slurry in a tape casting machine for tape casting to form first dielectric diaphragms of different thicknesses, and cutting the first dielectric diaphragms into ferrite dielectric diaphragms according to preset sizes;

[0009] S3, preparing a block diaphragm: laminating the ferrite dielectric diaphragm to form a block diaphragm;

[0010] S4, providing electrode slurry, wherein the electrode slurry is a metal conductive slurry;

[0011] S5, preparing an insulating ferrite slurry: providing a second ferrite magnetic powder, and adding an appropriate amount of a second solvent, a binder, a plasticizer, and a dispersant to the second ferrite magnetic powder to form a second slurry, and stirring the second slurry at high speed; placing the second slurry after high-speed stirring on the rolling mill for rolling treatment, and performing a second pretreatment on the second slurry after rolling treatment to form an insulating ferrite slurry; wherein the amount of the binder added is 15%-90% of the content of the second ferrite magnetic powder;

[0012] S6, screen printing process: fixing the block diaphragm at a preset position of a screen printer stage, and printing one to two layers of electrode slurry of a preset thickness on the block diaphragm according to a preset pattern, and then drying the layer to form an electrode magnetic sheet; printing one to two layers of insulating ferrite slurry of a preset thickness on the electrode magnetic sheet, and then drying the layer to form a first magnetic sheet coil;

[0013] S7, lamination process: vacuum-packing the first magnetic sheet coil, performing a water pressure treatment on the vacuum-packed first magnetic sheet coil, and cutting or punching the water pressure treated first magnetic sheet coil to form a second magnetic sheet coil;

[0014] S8, debinding and sintering treatment: performing debinding treatment and sintering treatment on the second magnetic sheet coil in sequence to form a third magnetic sheet coil;

[0015] S9, preparing a wireless charging coil: cleaning, soldering wires, testing, and packaging the third magnetic sheet coil in sequence to form a wireless charging coil.

[0016] Preferably, the first ferrite magnetic powder is a high resistivity soft magnetic material with a resistivity greater than 1 KΩ / mm, and the particle size range of the soft magnetic material is 0.1 μm-5 μm; the mixing ratio of the grinding ball unit, the first ferrite magnetic powder and the first solvent in S1 is: (2-5): (0.5-2): (0.5-2); the grinding ball unit includes two or more grinding balls of different diameters mixed in a ratio of 1:1, and the contour shape of the grinding balls can be circular or cylindrical; wherein the first solvent is formed by mixing an ester solvent, an alcohol solvent and a benzene solvent in pairs, and the mixing ratio of any two solvents among the ester solvent, the alcohol solvent and the benzene solvent is (3-9): (7-1); wherein the ester solvent includes n-propyl acetate and ethyl acetate; the alcohol solvent includes ethanol, isobutyl alcohol and isopropyl alcohol; the benzene solvent includes toluene; the binder resin is polyvinyl butyral or acrylic resin, and the polymerization degree molecular weight of the polyvinyl butyral is less than or equal to 100,000. The amount of the plasticizer added in S1 is 0.5%-3% of the content of the first ferrite magnetic powder, the amount of the dispersant added is 0.2%-3% of the content of the first ferrite magnetic powder, and the amount of the defoaming agent added is 0.2%-3% of the content of the first ferrite magnetic powder, wherein the plasticizer includes dioctyl phthalate, dibutyl phthalate and polymer ester.

[0017] Preferably, in S1, the second mixture and the third mixture are ball-milled by a ball mill, and the rotation speed of the ball mill is 20 rpm-80 rpm, the second mixture is ball-milled for 4 h-15 h, and the third mixture is ball-milled for 5 h-30 h.

[0018] Preferably, in S1, the second mixture and the third mixture are sand ground by a sand grinder, and the time for sand grinding the second mixture is 20 min-120 min, and the second mixture needs to be stirred before sand grinding, and the stirring time is 10 min-30 min; the time for sand grinding the third mixture is 40 min-300 min.

[0019] Preferably, the casting machine is any one of a steel belt casting machine, a carrier belt casting machine and a wet casting machine; the first pretreatment includes a first index detection and a first vacuum treatment, and the first index includes the viscosity, solid content and density of the first slurry; the second pretreatment includes a second index detection and a second vacuum treatment, and the second index includes the viscosity, solid content and fineness of the second slurry; the metal conductive paste is any one of a gold conductive paste, a silver conductive paste and a copper conductive paste, and the solid content of the metal conductive paste is 85%-95%, the metal particle size in the metal conductive paste ranges from 0.5μm to 3.0μm, and the thixotropic coefficient of the metal conductive paste is 5-50.

[0020] Preferably, the ferrite dielectric diaphragm is stacked in S3 to form a bar diaphragm, specifically including: S31, stacking the bar diaphragms neatly according to preset requirements; S32, pre-pressing the neatly stacked bar diaphragms, the pre-pressing pressure value is 0.1 tons-10 tons, and the pre-pressing time is 0.5min-10min.

[0021] Preferably, the preparation method of the adhesive in S5 specifically includes: providing a resin and a third solvent; mixing the resin and the third solvent and stirring and dissolving them at a temperature of 30°C-80°C to form the adhesive; wherein the resin includes polyvinyl butyral, cellulose resin and acrylic resin, and the ratio of the polyvinyl butyral, the cellulose resin and the acrylic resin is: (5-10): (3-5): (1-2), and at least one of the polyvinyl butyral, the cellulose resin and the acrylic resin has a molecular weight of polymerization greater than or equal to 1000; the proportion of the solvent in the adhesive is 50%-85%, and the solvent is an alcohol solvent or an ester solvent.

[0022] Preferably, the screen printer stage fixes the block diaphragm by means of a vacuum suction cup; in S6, the electrode slurry and the insulating ferrite slurry are printed by scraping glue, and the hardness of the scraping glue material is 50 degrees-95 degrees, and the scraping glue angle is 25 degrees-80 degrees; in S7, the first magnetic sheet coil after vacuum packaging is subjected to water pressure treatment, specifically including: placing the first magnetic sheet coil after vacuum packaging in water with a water temperature of 10℃-90℃, and subjecting the first magnetic sheet coil to water pressure treatment, the water pressure treatment time is 5min-100min, and the pressure value of the water pressure treatment is 0.05 tons / square centimeter-1 ton / square centimeter.

[0023] Preferably, the binder removal curve of the binder removal treatment is heating, keeping warm and cooling, and the heating rate in the binder removal treatment is 2°C / min-8°C / min, the maximum temperature of the binder removal treatment is 500°C, and the time of the binder removal treatment is 2h-6h; the sintering treatment adopts air sintering, and the sintering curve of the air sintering is heating, keeping warm and cooling, the heating time of the air sintering is 20h-50h, the insulation temperature of the air sintering is 880°C-930°C, and the cooling time of the air sintering is 5h-20h; wherein, dried air is added during the heating and cooling process of the air sintering.

[0024] The present invention also provides a wireless charger, which includes a wireless charging coil prepared by the above method.

[0025] Compared to related technologies, the present invention provides a method for preparing a wireless charging coil, the preparation process of which includes: preparing a dielectric magnetic powder slurry, preparing a ferrite dielectric diaphragm, preparing a bar block diaphragm, providing an electrode slurry, preparing an insulating ferrite slurry, screen printing, laminating, debinding and sintering, and preparing a wireless charging coil. Through this process, the magnetic sheet, electrode, and insulating magnetic material are sintered together, allowing the electrode and magnetic sheet to be tightly connected without gap loss. This not only improves power conversion efficiency, current resistance, and transmission power, but also enhances product performance and heat dissipation. Furthermore, the wireless charging coil manufactured using this method does not generate wastewater or other pollution during the production process, and is energy-saving and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic flow chart of a method for preparing a wireless charging coil according to the present invention;

[0027] Figure 2 Schematic diagram of the process of laminating ferrite dielectric diaphragms to form bar-shaped diaphragms in the present invention;

[0028] Figure 3 This is the printed pattern of the electrode paste printed on the block membrane in the present invention. DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing a wireless charging coil, aiming to solve the problems of large power loss, low power conversion efficiency, high manufacturing cost and pollution in traditional methods for preparing wireless charging coils.

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] Please see the attached Figure 1-3 As shown, the present invention provides a method for preparing a wireless charging coil, comprising the following steps:

[0032] S1, preparing a dielectric magnetic powder slurry: providing a grinding ball unit, a first ferrite magnetic powder and a first solvent, and mixing the grinding ball unit, the first ferrite magnetic powder and the first solvent in a preset ratio to form a first mixture; adding an appropriate amount of a plasticizer, a dispersant and a defoaming agent to the first mixture to form a second mixture; ball milling or sand milling the second mixture, and adding an adhesive resin to the second mixture after ball milling or sand milling to form a third mixture; ball milling or sand milling the third mixture to form a first slurry, and performing a first pretreatment on the first slurry to form a dielectric magnetic powder slurry.

[0033] Specifically, the first ferrite powder is a high resistivity soft magnetic material greater than 1KΩ / mm, and the particle size range of the soft magnetic material is 0.1μm-5μm (measured by a particle size analyzer or SEM electron microscope); the first pretreatment includes a first indicator detection and a first vacuum treatment, and the first indicator includes the viscosity, solid content and density of the first slurry.

[0034] In this embodiment, the mixing ratio of the grinding ball unit, the first ferrite magnetic powder and the first solvent is: (2-5): (0.5-2): (0.5-2); the grinding ball unit includes two or more grinding balls of different diameters mixed in a ratio of 1:1, and the contour shape of the grinding balls can be circular or cylindrical; wherein the first solvent is formed by mixing an ester solvent, an alcohol solvent and a benzene solvent in pairs, and the mixing ratio of any two solvents among the ester solvent, the alcohol solvent and the benzene solvent is (3-9): (7-1); wherein the ester solvent can be n-propyl acetate, ethyl acetate or other lipid series; the alcohol solvent can be alcohol such as ethanol, isobutyl alcohol, isopropyl alcohol; the benzene solvent includes toluene or other benzene series; the binder resin is polyvinyl butyral or acrylic resin, and when it is polyvinyl butyral, the degree of polymerization molecular weight of the polyvinyl butyral is less than or equal to 100,000.

[0035] Furthermore, the second mixture and the third mixture are ball-milled in a ball mill at a rotational speed of 20 to 80 rpm, and the second mixture is ball-milled for 4 to 15 hours; the third mixture is ball-milled for 5 to 30 hours. Of course, the second mixture and the third mixture can also be sand-milled in a sand mill. When sand-milling, the second mixture is sand-milled for 20 to 120 minutes, and the second mixture needs to be stirred before sand-milling, and the stirring time is 10 to 30 minutes. The third mixture is sand-milled for 40 to 300 minutes.

[0036] In this embodiment, the amount of the plasticizer added in S1 is 0.5%-3% of the content of the first ferrite magnetic powder, the amount of the dispersant added is 0.2%-3% of the content of the first ferrite magnetic powder, and the amount of the defoaming agent added is 0.2%-3% of the content of the first ferrite magnetic powder, wherein the plasticizer includes dioctyl phthalate, dibutyl phthalate and polymer ester.

[0037] S2, preparing a ferrite dielectric diaphragm: placing the dielectric magnetic powder slurry in a tape casting machine for tape casting to form first dielectric diaphragms of different thicknesses, and cutting the first dielectric diaphragms according to preset sizes to form ferrite dielectric diaphragms.

[0038] In this embodiment, the tape casting machine is any one of a steel tape casting machine, a carrier tape casting machine and a wet tape casting machine; and the first dielectric membrane is cut to form a ferrite dielectric membrane of a certain size, and the size can be adjusted according to actual conditions.

[0039] S3, preparing a bar block diaphragm: laminating the ferrite dielectric diaphragm to form a bar block diaphragm.

[0040] In this embodiment, the ferrite dielectric diaphragm is stacked to form a bar diaphragm, specifically including: S31, stacking the bar diaphragms neatly according to preset requirements; S32, pre-pressing the neatly stacked bar diaphragms, the pre-pressing pressure value is 0.1 tons-10 tons, and the pre-pressing time is 0.5 minutes-10 minutes; of course, the pre-pressing pressure value and pre-pressing time are set according to the required thickness of the bar diaphragm.

[0041] S4, providing electrode slurry, wherein the electrode slurry is a metal conductive slurry.

[0042] In this embodiment, the metal conductive paste is any one of a gold conductive paste, a silver conductive paste and a copper conductive paste, and the solid content of the metal conductive paste is 85%-95%, the metal particle size in the metal conductive paste is in the range of 0.5 μm-3.0 μm, and the thixotropic coefficient of the metal conductive paste (viscosity at 10 rpm to viscosity at 100 rpm) is 5-50.

[0043] S5, preparing an insulating ferrite slurry: providing a second ferrite magnetic powder, and adding an appropriate amount of a second solvent, an adhesive, a plasticizer and a dispersant to the second ferrite magnetic powder to form a second slurry, and stirring the second slurry at high speed; placing the second slurry after high-speed stirring on the rolling mill for rolling treatment, and performing a second pretreatment on the second slurry after rolling treatment to form an insulating ferrite slurry; wherein the amount of the adhesive added is 15%-90% of the content of the second ferrite magnetic powder.

[0044] It is worth mentioning that the preparation method of the adhesive in S5 specifically includes: providing a resin and a third solvent; mixing the resin and the third solvent and stirring and dissolving them at a temperature of 30°C-80°C to form the adhesive; wherein the resin includes polyvinyl butyral, cellulose resin and acrylic resin, and the ratio of the polyvinyl butyral, the cellulose resin and the acrylic resin is: (5-10): (3-5): (1-2), and at least one of the polyvinyl butyral, the cellulose resin and the acrylic resin has a molecular weight greater than or equal to 1000; the proportion of the solvent in the adhesive is 50%-85%, and the solvent is an alcohol solvent or an ester solvent. The second pretreatment includes a second indicator detection and a second vacuum treatment, and the second indicator includes the viscosity, solid content and fineness of the second slurry.

[0045] S6, screen printing process: fix the block film on the preset position of the screen printing machine carrier, and print the preset pattern (see attached) on the block film. Figure 3 As shown in the figure, 1-2 layers of electrode paste of preset thickness are printed and then dried to form an electrode magnetic sheet; 1-2 layers of insulating ferrite paste of preset thickness are printed on the electrode magnetic sheet and then dried to form a first magnetic sheet coil.

[0046] In this embodiment, the screen printer stage fixes the block diaphragm by means of a vacuum suction cup, and then moves it to the corresponding position for printing; in S6, the electrode paste and the insulating ferrite paste are printed by scraping glue, and the hardness of the scraping glue is between 50 degrees and 95 degrees, and the scraping glue angle is between 25 degrees and 80 degrees. In addition, it should be noted that the attached Figure 3The white part in the figure is the printed electrode paste pattern, which is represented by number 1 in the figure. Figure 3 The black portion in the figure shown is formed by the dielectric magnetic powder slurry and is represented by the serial number 2.

[0047] S7, lamination treatment: vacuum-packing the first magnetic sheet coil, performing water pressure treatment on the vacuum-packed first magnetic sheet coil, and cutting or punching the water pressure treated first magnetic sheet coil to form a second magnetic sheet coil.

[0048] In this embodiment, the first magnetic sheet coil after vacuum packaging is subjected to a water pressure treatment in S7, specifically including: placing the vacuum-packed first magnetic sheet coil in water at a temperature of 10°C-90°C, and subjecting the first magnetic sheet coil to a water pressure treatment, wherein the water pressure treatment time is 5 minutes to 100 minutes, and the pressure value of the water pressure treatment is 0.05 tons / square centimeter to 1 ton / square centimeter. In addition, the first magnetic sheet coil is cut or punched to form a single small piece of the second magnetic sheet coil (including the bottom magnetic isolation sheet and the surface electrode coil), and the time, temperature, and pressure value of the water pressure treatment of the first magnetic sheet coil are adjusted and set according to the thickness of the first magnetic sheet coil, and the time, temperature, and pressure value of the water pressure treatment are different for different thicknesses.

[0049] S8, debinding and sintering treatment: performing debinding and sintering treatment on the second magnetic sheet coil to form a third magnetic sheet coil.

[0050] In order to ensure the compactness and flatness of the magnetic sheet coil (due to the thinness and large area of ​​the magnetic sheet, it is easy to bend and deform, etc.), in this embodiment, the binder removal curve of the binder removal treatment is heating, keeping warm and cooling, and the heating rate in the binder removal treatment is 2℃ / min-8℃ / min, the maximum temperature of the binder removal treatment is 500℃, and the time of the binder removal treatment is 2h-6h. In addition, the sintering speed of the sintering treatment after the binder removal treatment should be slow, and the binder removal phenomenon is carried out once in the early stage. Air sintering is adopted during sintering, and the sintering curve of the air sintering is heating, keeping warm and cooling, the heating time of the air sintering is 20h-50h, the insulation temperature of the air sintering is 880℃-930℃, and the cooling time of the air sintering is 5h-20h; wherein, the air sintering is added with dried air during the heating and cooling process to ensure that the air is fully oxygenated, improve the insulation resistance value of the magnet sintering, and reduce its own loss.

[0051] S9, preparing a wireless charging coil: cleaning, soldering wires, testing, and packaging the third magnetic sheet coil in sequence to form a wireless charging coil.

[0052] In this embodiment, the test indicators include size, inductance, Q (quality factor) value, direct current resistance (DCR), wireless charging conversion efficiency and standby power consumption.

[0053] In addition, the present invention also provides a wireless charger, which includes a wireless charging coil prepared by the above method.

[0054] Two specific embodiments are listed below to further illustrate the present invention;

[0055] Implementation Method 1

[0056] S1. Prepare the dielectric magnetic powder slurry: Select nickel-zinc ferrite magnetic powder with a resistivity greater than 200 MΩ / mm (millimeter) and a particle size of 1.8 μm. First, mix the grinding balls, nickel-zinc ferrite magnetic powder, and the first solvent in a ratio of 2:1:1. Then, add the plasticizer, dispersant, and defoamer in the following amounts, calculated based on the nickel-zinc ferrite magnetic powder: 3.5% plasticizer DOP, 0.2% dispersant, and 0.2% defoamer. The first solvent used is n-propyl acetate and ethanol in a ratio of 9:1. After the mixture is ball milled at 45 rpm for 5 hours, a binder resin is added. After another 25 hours of ball milling, viscosity, solids content, and density are tested. If the test results meet the requirements, the dielectric magnetic powder slurry is obtained. The binder resin used is polyvinyl butyral (PVB), with a molecular weight of 80,000-90,000.

[0057] S2, preparing a ferrite dielectric diaphragm: casting a first dielectric diaphragm with a thickness of 60 μm on a steel strip casting machine, and cutting the first dielectric diaphragm to obtain a ferrite dielectric diaphragm; and the size of the ferrite dielectric diaphragm is 220 mm×220 mm×0.06 mm.

[0058] S3, preparing a block diaphragm: stacking the cut ferrite dielectric diaphragms neatly according to the design requirements, and then pre-pressing them with a pressure of 0.1 tons for 0.5 minutes to 10 minutes to obtain a block diaphragm.

[0059] S4, providing electrode slurry: the electrode slurry is silver conductive slurry, and the solid content of the silver conductive slurry is 90%.

[0060] S5, preparing insulating ferrite slurry: Take ferrite magnetic powder material, add 50% binder (by weight of the ferrite magnetic powder material), a second solvent, a plasticizer, a dispersant, etc., and stir at high speed. Then, roll it twice on a roller mill. After achieving the required fineness, test the viscosity, solid content, fineness, and vacuum. After the test meets the preset requirements, the insulating ferrite slurry is obtained. Prepare the binder by adding the resin and the third solvent according to the designed ratio and stirring and dissolving them at 40°C. The resin ratio in the binder is: polyvinyl butyral (PVB): cellulose resin: acrylic resin = 6:3:1, and the weight proportion of the solvent in the binder is 77.5%.

[0061] S6, screen printing process: fix the block film on the preset position of the screen printing machine carrier, the carrier uses a vacuum suction cup to suck the film, and then moves to the corresponding position for printing. The hardness of the printing scraper is 75 degrees. Print the block film according to the preset pattern (attached Figure 3 As shown in FIG, first print a layer of electrode paste of required thickness and then print a layer of insulating ferrite paste, and dry them after printing to obtain a first magnetic sheet coil.

[0062] S7, lamination process: the first magnetic sheet coil after printing and drying is vacuum-packed, and then pressed in water at a pressure of 0.2 tons / square centimeter and a temperature of 50°C for 30 minutes, and then cut or punched to obtain the second magnetic sheet coil.

[0063] S8, debinding and sintering treatment: In order to ensure the density and flatness of the magnetic sheet coil (due to the thinness and large area of ​​the magnetic sheet, it is easy to bend and deform, etc.), the second magnetic sheet coil is quickly pre-debinded, the debinding heating rate is 2.5℃ / minute, the maximum temperature is 500℃, and the total debinding time is 6 hours; after debinding, sintering is carried out, the sintering speed should be slow, and debinding should be carried out once in the early stage. Air sintering is used during sintering, and the sintering curve setting should be perfect. The heating time is 50h, the insulation temperature is 890℃, the time is 4h, and the cooling time is 15h. It is necessary to add dried air when heating and cooling to ensure that the air is fully oxygenated, improve the insulation resistance value of the magnet sintering, and reduce its own loss. Through this step, the third magnetic sheet coil is obtained.

[0064] S9, preparing a wireless charging coil: cleaning, soldering leads, testing and packaging the third magnetic sheet coil in sequence, and obtaining a wireless charging coil after passing the test.

[0065] The test data of the wireless charging coil manufactured by the preparation method of the above embodiment 1 is as follows:

[0066]

[0067] Two specific production methods are listed below to further illustrate the present invention;

[0068] Implementation Method 2

[0069] S1. Prepare the dielectric magnetic powder slurry: Select nickel-zinc ferrite magnetic powder with a resistivity greater than 100 MΩ / mm (millimeter) and a particle size of 2 μm. First, mix the grinding balls, nickel-zinc ferrite magnetic powder, and the first solvent in a ratio of 2:1:1. Then, add the plasticizer, dispersant, and defoamer in the following amounts, calculated based on the nickel-zinc ferrite magnetic powder: plasticizer DOP: 3%, dispersant: 0.2%, and defoamer: 0.2%. The first solvent used is n-propyl acetate and ethanol in a ratio of 8:2. After the mixture is ball milled at 45 rpm for 5 hours, a binder resin is added. After another 20 hours of ball milling, the viscosity, solids content, and density are tested. If the test results meet the requirements, the dielectric magnetic powder slurry is obtained. The binder resin used is polyvinyl butyral (PVB), with a molecular weight of 80,000-90,000.

[0070] S2, preparing a ferrite dielectric diaphragm: casting a first dielectric diaphragm with a thickness of 60 μm on a steel strip casting machine, and cutting the first dielectric diaphragm to obtain a ferrite dielectric diaphragm; and the size of the ferrite dielectric diaphragm is 220 mm×220 mm×0.06 mm.

[0071] S3, preparing a block diaphragm: stacking the cut ferrite dielectric diaphragms neatly according to the design requirements, and then pre-pressing them with a pressure of 0.1 tons for 0.5 minutes to 10 minutes to obtain a block diaphragm.

[0072] S4, providing electrode slurry: the electrode slurry is silver conductive slurry, and the solid content of the silver conductive slurry is 90%.

[0073] S5, preparing insulating ferrite slurry: Take ferrite magnetic powder material, add 50% binder (by weight of the ferrite magnetic powder material), a second solvent, a plasticizer, a dispersant, etc., and stir at high speed. Then, roll it twice on a roller mill. After achieving the required fineness, test the viscosity, solid content, fineness, and vacuum. Once the test meets the preset requirements, the insulating ferrite slurry is obtained. Prepare the binder by adding the resin and the third solvent according to the designed ratio and stirring and dissolving them at 40°C. The resin ratio in the binder is: polyvinyl butyral (PVB): cellulose resin: acrylic resin = 6:3:1, and the weight proportion of the solvent in the binder is 75%.

[0074] S6, screen printing process: fix the block film on the preset position of the screen printing machine carrier, the carrier uses a vacuum suction cup to suck the film, and then moves to the corresponding position for printing. The hardness of the printing scraper is 75 degrees. Print the block film according to the preset pattern (attached Figure 3As shown in FIG, first print a layer of electrode paste of required thickness and then print a layer of insulating ferrite paste, and dry them after printing to obtain a first magnetic sheet coil.

[0075] S7, lamination process: the first magnetic sheet coil after printing and drying is vacuum-packed, and then pressed in water at a pressure of 0.2 tons / square centimeter and a temperature of 50°C for 30 minutes, and then cut or punched to obtain the second magnetic sheet coil.

[0076] S8, debinding and sintering treatment: In order to ensure the density and flatness of the magnetic sheet coil (due to the thinness and large area of ​​the magnetic sheet, it is easy to bend and deform, etc.), the second magnetic sheet coil is quickly pre-debinded, the debinding heating rate is 4℃ / minute, the maximum temperature is 500℃, and the total debinding time is 4 hours; after debinding, sintering is carried out, the sintering speed should be slow, and debinding should be carried out once in the early stage. Air sintering is used during sintering, and the sintering curve setting should be perfect. The heating time is 40h, the insulation temperature is 890℃, the time is 4h, and the cooling time is 10h. It is necessary to add dried air when heating and cooling to ensure that the air is fully oxygenated, improve the insulation resistance value of the magnet sintering, and reduce its own loss. Through this step, the third magnetic sheet coil is obtained.

[0077] S9, preparing a wireless charging coil: cleaning, soldering leads, testing and packaging the third magnetic sheet coil in sequence, and obtaining a wireless charging coil after passing the test.

[0078] The test data of the wireless charging coil manufactured by the preparation method of the above embodiment 2 is as follows:

[0079]

[0080] Compared to related technologies, the present invention provides a method for preparing a wireless charging coil, the preparation process of which includes: preparing a dielectric magnetic powder slurry, preparing a ferrite dielectric diaphragm, preparing a bar block diaphragm, providing an electrode slurry, preparing an insulating ferrite slurry, screen printing, laminating, debinding and sintering, and preparing a wireless charging coil. Through this process, the magnetic sheet, electrode, and insulating magnetic material are sintered together, allowing the electrode and magnetic sheet to be tightly connected without gap loss. This not only improves power conversion efficiency, current resistance, and transmission power, but also enhances product performance and heat dissipation. Furthermore, the wireless charging coil manufactured using this method does not generate wastewater or other pollution during the production process, and is energy-saving and environmentally friendly.

[0081] The embodiments described above are to be understood as illustrative rather than limiting the scope of the present invention, which is to be determined by the claims. It will be apparent to those skilled in the art that non-essential improvements and adjustments to the present invention, without departing from the spirit and scope of the present invention, still fall within the scope of the present invention.

Claims

1. A method for preparing a wireless charging coil, characterized in that: The method for preparing the wireless charging coil comprises the following steps: S1, preparing a dielectric magnetic powder slurry: providing a grinding ball unit, a first ferrite magnetic powder, and a first solvent, and mixing the grinding ball unit, the first ferrite magnetic powder, and the first solvent in a preset ratio to form a first mixture; adding an appropriate amount of a plasticizer, a dispersant, and a defoaming agent to the first mixture to form a second mixture; ball milling or sand milling the second mixture, and adding a binder resin to the ball-milled or sand-milled second mixture to form a third mixture; ball milling or sand milling the third mixture to form a first slurry, and performing a first pretreatment on the first slurry to form a dielectric magnetic powder slurry; S2, preparing a ferrite dielectric diaphragm: placing the dielectric magnetic powder slurry in a tape casting machine for tape casting to form first dielectric diaphragms of different thicknesses, and cutting the first dielectric diaphragms into ferrite dielectric diaphragms according to preset sizes; S3, preparing a block diaphragm: laminating the ferrite dielectric diaphragm to form a block diaphragm; S4, providing electrode slurry, wherein the electrode slurry is a metal conductive slurry; S5, preparing an insulating ferrite slurry: providing a second ferrite magnetic powder, and adding an appropriate amount of a second solvent, a binder, a plasticizer, and a dispersant to the second ferrite magnetic powder to form a second slurry, and stirring the second slurry at high speed; placing the second slurry after high-speed stirring on a rolling mill for rolling, and performing a second pretreatment on the second slurry after rolling to form an insulating ferrite slurry; wherein the amount of the binder added is 15%-90% of the content of the second ferrite magnetic powder; S6, screen printing process: fixing the block diaphragm at a preset position of a screen printer stage, and printing one to two layers of electrode slurry of a preset thickness on the block diaphragm according to a preset pattern, and then drying the layer to form an electrode magnetic sheet; printing one to two layers of insulating ferrite slurry of a preset thickness on the electrode magnetic sheet, and then drying the layer to form a first magnetic sheet coil; S7, lamination process: vacuum-packing the first magnetic sheet coil, performing a water pressure treatment on the vacuum-packed first magnetic sheet coil, and cutting or punching the water pressure treated first magnetic sheet coil to form a second magnetic sheet coil; S8, debinding and sintering treatment: performing debinding treatment and sintering treatment on the second magnetic sheet coil in sequence to form a third magnetic sheet coil; S9, preparing a wireless charging coil: cleaning, soldering wires, testing, and packaging the third magnetic sheet coil in sequence to form a wireless charging coil.

2. The method for preparing a wireless charging coil according to claim 1, wherein: The first ferrite powder is a soft magnetic material with a high resistivity greater than 1KΩ / mm, and the particle size of the soft magnetic material is in the range of 0.1µm-5µm; In S1, the mixing ratio of the grinding ball unit, the first ferrite magnetic powder and the first solvent is: (2-5): (0.5-2): (0.5-2); the grinding ball unit includes two or more grinding balls of different diameters mixed in a ratio of 1:1, and the contour shape of the grinding balls is circular or cylindrical; wherein the first solvent is formed by mixing any two of an ester solvent, an alcohol solvent and a benzene solvent, and the mixing ratio of any two of the ester solvent, the alcohol solvent and the benzene solvent is (3-9): (7-1); wherein the ester solvent includes n-propyl acetate and ethyl acetate; the alcohol solvent includes ethanol, isobutyl alcohol and isopropyl alcohol; the benzene solvent includes toluene; the binder resin is polyvinyl butyral or acrylic resin, and the degree of polymerization molecular weight of the polyvinyl butyral is less than or equal to 100,000; The amount of the plasticizer added in S1 is 0.5%-3% of the content of the first ferrite magnetic powder, the amount of the dispersant added is 0.2%-3% of the content of the first ferrite magnetic powder, and the amount of the defoaming agent added is 0.2%-3% of the content of the first ferrite magnetic powder, wherein the plasticizer includes dioctyl phthalate, dibutyl phthalate and polymer ester.

3. The method for preparing a wireless charging coil according to claim 1, wherein: In S1, the second mixture and the third mixture are ball-milled by a ball mill, and the rotation speed of the ball mill is 20 rpm to 80 rpm. The second mixture is ball-milled for 4 h to 15 h; and the third mixture is ball-milled for 5 h to 30 h.

4. The method for preparing a wireless charging coil according to claim 1, wherein: In S1, the second mixture and the third mixture are sand-milled by a sand mill, and the sand-milling time for the second mixture is 20 min-120 min. Before the sand-milling, the second mixture needs to be stirred, and the stirring time is 10 min-30 min; the sand-milling time for the third mixture is 40 min-300 min.

5. The method for preparing a wireless charging coil according to claim 1, wherein: The tape casting machine is any one of a steel tape casting machine, a carrier tape casting machine and a wet tape casting machine; the first pretreatment includes a first indicator detection and a first vacuum treatment, and the first indicator includes the viscosity, solid content and density of the first slurry; the second pretreatment includes a second indicator detection and a second vacuum treatment, and the second indicator includes the viscosity, solid content and fineness of the second slurry; the metal conductive paste is any one of a gold conductive paste, a silver conductive paste and a copper conductive paste, and the solid content of the metal conductive paste is 85%-95%, the metal particle size in the metal conductive paste ranges from 0.5µm to 3.0µm, and the thixotropic coefficient of the metal conductive paste is 5-50.

6. The method for preparing a wireless charging coil according to claim 1, wherein: In the said S3, the ferrite dielectric diaphragm is stacked to form a bar block diaphragm, specifically including: S31, stacking the bar block diaphragms neatly according to preset requirements; S32, pre-pressing the neatly stacked bar block diaphragms, the pre-pressing pressure value is 0.1 tons-10 tons, and the pre-pressing time is 0.5min-10min.

7. The method for preparing a wireless charging coil according to claim 1, wherein: The preparation method of the adhesive described in S5 specifically includes: providing a resin and a third solvent; mixing the resin and the third solvent, stirring and dissolving them at a temperature of 30°C-80°C to form the adhesive; wherein the resin includes polyvinyl butyral, cellulose resin and acrylic resin, and the ratio of the polyvinyl butyral, the cellulose resin and the acrylic resin is: (5-10): (3-5): (1-2), and at least one of the polyvinyl butyral, the cellulose resin and the acrylic resin has a molecular weight of polymerization greater than or equal to 1000; the proportion of the solvent in the adhesive is 50%-85%, and the solvent is an alcohol solvent or an ester solvent.

8. The method for preparing a wireless charging coil according to claim 1, wherein: The screen printing machine stage fixes the block diaphragm by means of a vacuum suction cup; in S6, the electrode slurry and the insulating ferrite slurry are printed by scraping glue, and the hardness of the scraping glue material is 50 degrees-95 degrees, and the scraping glue angle is 25 degrees-80 degrees; in S7, the first magnetic sheet coil after vacuum packaging is subjected to water pressure treatment, specifically including: placing the first magnetic sheet coil after vacuum packaging in water with a water temperature of 10℃-90℃, and subjecting the first magnetic sheet coil to water pressure treatment, the water pressure treatment time is 5min-100min, and the pressure value of the water pressure treatment is 0.05 tons / square centimeter-1 ton / square centimeter.

9. The method for preparing a wireless charging coil according to claim 1, wherein: The debinding curve of the debinding treatment is heating, keeping warm and cooling, and the heating rate in the debinding treatment is 2°C / min-8°C / min, the maximum temperature of the debinding treatment is 500°C, and the time of the debinding treatment is 2h-6h; the sintering treatment adopts air sintering, and the sintering curve of the air sintering is heating, keeping warm and cooling, the heating time of the air sintering is 20h-50h, the insulation temperature of the air sintering is 880°C-930°C, and the cooling time of the air sintering is 5h-20h; wherein, dried air is added during the heating and cooling process of the air sintering.

10. A wireless charger, characterized in that: The wireless charger includes a wireless charging coil manufactured by the manufacturing method according to any one of claims 1 to 9.

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