A copper-iron co-fired inductor containing an iron-based amorphous alloy and its preparation method

Abstract

This disclosure relates to the field of electronic materials, providing a copper-iron co-fired inductor containing an iron-based amorphous alloy and its preparation method. The method includes: mixing carbonyl iron powder, crystalline soft magnetic alloy powder, and iron-based amorphous alloy powder in a specific ratio to obtain a soft magnetic composite powder; placing the soft magnetic composite powder in a composite insulating solution for insulating coating, then adding a first glass powder and granulating to obtain shaped granules; coating a copper conductor in an insulating slurry containing a second glass powder, drying, and then embedding the copper conductor in the shaped granules and pressing to obtain an inductor green blank; and subjecting the inductor green blank to segmented co-firing and gradient annealing in a protective atmosphere to obtain the copper-iron co-fired inductor containing an iron-based amorphous alloy. This effectively improves the problems of increased core loss and permeability drift that easily occur in existing copper-iron co-fired inductors under high temperature, high frequency, and high current conditions.

Description

Technical Field

[0001] This disclosure relates to the field of electronic materials, and more specifically, to a copper-iron co-fired inductor containing an iron-based amorphous alloy and its preparation method. Background Technology

[0002] Co-fired copper-iron inductors are a new type of power inductor component formed by integrating soft magnetic metal powder with copper conductors through high-temperature sintering. Compared to traditional one-piece molded inductors that use organic resin bonding, the organic matter in co-fired copper-iron inductors is completely removed during the sintering process. The soft magnetic powders are bonded together by inorganic grain boundary phases or glass, resulting in higher saturation current, lower core loss, and excellent high-temperature reliability (capable of long-term operation above 150℃). This meets the stringent power inductor requirements of high-end applications such as AI servers, new energy vehicle electric drive systems, and photovoltaic inverters.

[0003] Currently, soft magnetic composite materials for copper-iron co-fired inductors mainly employ single or mixed gas-atomized spherical soft magnetic alloy powders (such as iron-silicon-chromium, iron-silicon-aluminum, iron-nickel, and iron-nickel-molybdenum), and meet the process requirements of high-pressure molding and high-temperature sintering by constructing multiple insulating coating layers (such as phosphate passivation layers, oxide precursor layers, and organic / inorganic silicone resin layers) on their surface. For example, existing technologies have obtained copper-iron co-fired inductors with high permeability and low loss by graded mixing of gas-atomized iron-silicon-chromium or iron-nickel-molybdenum powders of different particle sizes, adding coating agents, and combining them with gradient annealing processes. Other approaches use carbonyl iron powder, iron-silicon-chromium, etc., as the matrix, and construct high-temperature resistant insulating layers using inorganic acids and oxide precursors.

[0004] However, the aforementioned material system based on crystalline alloy powder has significant limitations in further improving the overall performance of copper-iron co-fired inductors. To obtain high density and high permeability, extremely high molding pressure (>1500MPa) is usually required. This increases the risk of damage to the insulating coating layer on the surface of the powder particles, resulting in local defects. After long-term high-temperature operation, the insulation withstand voltage decreases, eddy current losses increase, leading to increased core losses and permeability drift in the finished inductor.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure. Summary of the Invention

[0006] The purpose of this disclosure is to provide a copper-iron co-fired inductor containing an iron-based amorphous alloy and its preparation method, thereby solving the problems of increased core loss and permeability drift in existing co-fired inductors.

[0007] Other features and advantages of this disclosure will become apparent from the following detailed description, or may be learned in part from practice of this disclosure.

[0008] According to one aspect of this disclosure, a method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy is provided, the steps of which include: S1. Mix carbonyl iron powder, crystalline soft magnetic alloy powder and iron-based amorphous alloy powder in a certain proportion to obtain soft magnetic composite powder; S2. The soft magnetic composite powder is placed in a composite insulating solution for insulating coating, and then the first glass powder is added and granulated to obtain shaped granules. The composite insulating solution includes an oxide insulating precursor and a silicone resin coating component. S3. The copper conductor is placed in an insulating slurry containing the second glass powder for coating treatment. After drying, the copper conductor is embedded in the molding granules and pressed to obtain the inductor blank. The softening temperature of the second glass powder is higher than that of the first glass powder. S4. The inductor blank is placed in a protective atmosphere for segmented co-firing and gradient annealing. The ends of the copper conductor are then ground to form leads. The leads are plated with at least three layers of metal. The part excluding the leads is insulated and encapsulated to obtain a copper-iron co-fired inductor containing an iron-based amorphous alloy.

[0009] According to one aspect of this disclosure, a copper-iron co-fired inductor containing an iron-based amorphous alloy is provided, manufactured by the above-described method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy. The copper-iron co-fired inductor containing the iron-based amorphous alloy comprises: Carbonyl iron powder is used to improve the saturation magnetic induction intensity and high current carrying capacity of copper-iron co-fired inductors. Crystalline soft magnetic alloy powder is used to construct the magnetic framework of copper-iron co-fired inductors; Iron-based amorphous alloy powder is used to improve the permeability of copper-iron co-fired inductors and reduce high-frequency losses. The first glass powder is used to promote sintering densification; The second glass powder is used to isolate the copper conductor from magnetic materials.

[0010] As can be seen from the above technical solutions, the exemplary embodiments disclosed herein possess at least the following advantages and positive effects: In some embodiments of this disclosure, the technical solutions provided, on the one hand, solve the problem of insufficient interparticle insulation stability and easy formation of eddy current channels leading to increased core loss in the prior art of soft magnetic powder under high temperature co-firing and high frequency operating conditions. This is achieved by using a technique of mixing carbonyl iron powder, crystalline soft magnetic alloy powder and iron-based amorphous alloy powder in a certain proportion to form soft magnetic composite powder, and then placing the soft magnetic composite powder in a composite insulating solution including oxide insulating precursor and silicone resin coating components for insulating coating. This achieves the technical effect of improving the interparticle insulation isolation capability of soft magnetic powder, reducing high frequency loss and improving magnetic performance stability.

[0011] On the other hand, by adding the first glass powder to the shaped granules and making the softening temperature of the second glass powder on the surface of the copper conductor higher than that of the first glass powder, the problem of difficulty in simultaneously achieving magnetic powder densification and copper conductor insulation protection in the prior art is further overcome. This achieves the technical effect of the first glass powder promoting magnetic powder bonding during co-firing and the second glass powder maintaining the continuity of copper conductor insulation.

[0012] In summary, this technical solution, through the synergistic combination of iron-based amorphous alloy soft magnetic composite powder, composite insulation coating, the softening temperature difference between the first and second glass powders, segmented co-firing, and gradient annealing, enables the copper-iron co-fired inductor to form an integrated sintered structure while simultaneously ensuring core compactness, copper conductor insulation reliability, and magnetic performance stability under high-temperature service. This improves the problems of increased core loss and permeability drift that easily occur in existing copper-iron co-fired inductors under high temperature, high frequency, and high current conditions.

[0013] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0014] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings: Figure 1 This is a schematic flowchart of a method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy in one embodiment. Figure 2 The DSC curves of the iron-based amorphous alloy powders used in Examples 1-4 are shown. Figure 3 The image shown is a scanning electron microscope (SEM) image of the iron-based amorphous alloy powder selected in step S1.1 of Example 1, with a magnification of 2000x. Figure 4 The image shown is a low-magnification scanning electron microscope image of the iron-based amorphous alloy powder selected in step S1.1 of Example 1, with a magnification of 1000x. Figure 5 This is a scanning electron microscope image of the soft magnetic composite powder obtained after ball milling and mixing in step S1 of Example 1; Figure 6 This is a scanning electron microscope image of another location of the soft magnetic composite powder obtained after ball milling and mixing in step S1 of Example 1; Figure 7 This is a scanning electron microscope image of another location of the soft magnetic composite powder obtained after ball milling and mixing in step S1 of Example 1. Figure 8 This is a scanning electron microscope image of a local location of the soft magnetic composite powder obtained after ball milling and mixing in step S1 of Example 1; Figure 9 This is a scanning electron microscope image of another local location of the soft magnetic composite powder obtained after ball milling and mixing in step S1 of Example 1; Figure 10 This is a scanning electron microscope image of another local location of the soft magnetic composite powder obtained after ball milling and mixing in step S1 of Example 1. Detailed Implementation

[0015] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art.

[0016] Furthermore, the described features or characteristics may be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure may be practiced without one or more of the specific details, or other methods, steps, etc. may be employed. In other instances, well-known methods, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0017] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0018] like Figure 1 As shown, a method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy includes the following steps: S1. Mix carbonyl iron powder, crystalline soft magnetic alloy powder and iron-based amorphous alloy powder in a certain proportion to obtain soft magnetic composite powder.

[0019] Step S1 includes: S1.1 Select carbonyl iron powder with D50 of 3-6μm, crystalline soft magnetic alloy powder with D50 of 10-30μm, and iron-based amorphous alloy powder with D50 of 10-25μm. The mass ratio of carbonyl iron powder: crystalline soft magnetic alloy powder: iron-based amorphous alloy powder is 30-45: 20-35: 15-30. S1.2 Place the iron-based amorphous alloy powder in a tube furnace and heat it to 430-500°C at a rate of 2-5°C / min under a nitrogen-hydrogen mixed atmosphere. Hold the temperature for 10-40 minutes and then cool it to room temperature to obtain heat-treated iron-based amorphous alloy powder. S1.3. Carbonyl iron powder and crystalline soft magnetic alloy powder are added in batches to heat-treated iron-based amorphous alloy powder. The mixture is ball-milled under nitrogen or argon protection. Zirconia balls are used as the milling medium. The ball-to-material mass ratio is controlled at 3:1 to 8:1. A combination of large and small balls is used as the milling medium. The diameter of the large balls is 5 to 10 mm and the diameter of the small balls is 2 to 5 mm. The mass ratio of large to small balls is 1:1 to 3:1. The ball milling speed is controlled at 150 to 250 r / min and the ball milling time is 30 to 120 min to obtain soft magnetic composite powder.

[0020] In one embodiment, between step S1.2 and step S1.3, step S1 further includes: Heat-treated iron-based amorphous alloy powder was added to an ethanol-water mixture and an inducing agent was added. The mixture was stirred at 40–70°C for 30–90 min and then dried. The inducing agent includes at least one of phosphosilicate sol, borosilicate sol, niobate sol, and molybdate sol, and the amount of the inducing agent is 0.05 to 0.6% of the mass of the iron-based amorphous alloy powder.

[0021] In one embodiment, after step S1.3, step S1 further includes: Add volatile solvents and interface conditioning agents to the soft magnetic composite powder, stir it in a mixer at 20-50 r / min for 10-30 min, dry it at 50-70℃ for 1-3 h, then place it in a nitrogen-protected drum mixer and stir it at 5-15 r / min for 20-60 min, and pass it through a 60-120 mesh sieve. The volatile solvent includes at least one of anhydrous ethanol, acetone, and isopropanol, and the amount of volatile solvent used is 2 to 6% of the mass of the soft magnetic composite powder. The interface conditioning agent includes at least one of polyvinylpyrrolidone, silane coupling agent, phosphate ester dispersant, and carboxylate dispersant, and the amount of interface conditioning agent used is 0.03 to 0.15% of the mass of the soft magnetic composite powder.

[0022] This step involves particle size matching, preheating, and ball milling of carbonyl iron powder, crystalline soft magnetic alloy powder, and iron-based amorphous alloy powder to ensure uniform distribution of the three powders, resulting in a soft magnetic composite powder suitable for subsequent coating, granulation, and pressing. The carbonyl iron powder, with its smaller particle size, fills the gaps between the crystalline soft magnetic alloy powder particles, increasing the powder packing density. The crystalline soft magnetic alloy powder forms a stable magnetic framework. The iron-based amorphous alloy powder serves as a functional component in the subsequent co-firing process, forming fine iron nanocrystals and residual amorphous phases during sintering, which helps improve magnetic permeability and reduce high-frequency losses.

[0023] In one embodiment, the inducing agent sol is prepared by the following steps: Ethanol, deionized water, and a weak acid regulator are mixed to obtain an alcohol-water hydrolysis medium. The weak acid regulator includes at least one of acetic acid, citric acid, oxalic acid, or lactic acid. The pH of the alcohol-water hydrolysis medium is controlled at 3.0–5.5. A silicon source is added to the alcohol-water hydrolysis medium and stirred at 25–50°C for 20–60 min to pre-hydrolyze the silicon source, resulting in a silicon-containing pre-hydrolyzed solution. The silicon source includes at least one of tetraethyl orthosilicate, methyltriethoxysilane, sodium silicate aqueous solution, or silica sol.

[0024] When preparing phosphosilicate sol, a phosphorus source is added to the silicon-containing pre-hydrolyzed solution. The phosphorus source includes at least one of phosphoric acid, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, or phosphate ester compounds. The mixture is stirred at 30–60°C for 30–120 min to form a phosphorus-silicon colloidal dispersion system with the silicon-containing pre-hydrolyzed solution, thus obtaining the phosphosilicate sol.

[0025] When preparing borosilicate sol, a boron source is added to the silicon-containing pre-hydrolyzed solution. The boron source includes at least one of boric acid, ammonium borate, borate esters or borates. The mixture is stirred at 30–60°C for 30–120 min to form a borosilicate colloidal dispersion system with the silicon-containing pre-hydrolyzed solution, thus obtaining the borosilicate sol.

[0026] When preparing niobate sol, a niobium source is added to an alcohol-water hydrolysis medium, and a complexing agent is added for stable dispersion. The niobium source includes at least one of niobium ammonium oxalate, niobate, niobium alkoxide, or niobium-containing hydrolysis precursor. The complexing agent includes at least one of citric acid, oxalic acid, lactic acid, or acetylacetone. The mixture is stirred at 30–70°C for 30–120 min to form a niobium-containing colloidal dispersion system, thus obtaining the niobate sol.

[0027] When preparing molybdate sol, a molybdenum source is added to an alcohol-water hydrolysis medium, and a complexing agent or dispersing stabilizer is added for stable dispersion. The molybdenum source includes at least one of ammonium molybdate, sodium molybdate, phosphomolybdic acid, or a molybdenum-containing hydrolysis precursor. The complexing agent or dispersing stabilizer includes at least one of citric acid, oxalic acid, polyvinylpyrrolidone, or a phosphate ester dispersant. The mixture is stirred at 30–70°C for 30–120 min to form a molybdenum-containing colloidal dispersion system, thus obtaining the molybdate sol.

[0028] In addition, ball milling under nitrogen or argon protection can reduce oxidation and mechanical damage to iron-based amorphous alloy powder. Adding volatile solvents such as anhydrous ethanol, acetone or isopropanol, as well as interface modifiers such as polyvinylpyrrolidone, silane coupling agents, phosphate ester dispersants or carboxylate dispersants can improve the dispersion state between different powders, reduce agglomeration and segregation, and make the soft magnetic composite powder have better flowability and pressing uniformity.

[0029] By preheating and inducing agent treatment of iron-based amorphous alloy powder, the problems of uneven crystallization and easy grain coarsening of amorphous powder during co-firing were solved, thereby improving the high-temperature magnetic performance stability of copper-iron co-fired inductors. By ball milling and interface adjustment, the problems of easy segregation and agglomeration of powders with different particle sizes were solved, thereby improving the consistency of subsequent molding and co-firing.

[0030] S2. The soft magnetic composite powder is placed in a composite insulating solution for insulating coating, and then the first glass powder is added and granulated to obtain shaped granules. The composite insulating solution includes an oxide insulating precursor and a silicone resin coating component.

[0031] A pressure-resistant and heat-resistant composite insulating layer is formed on the surface of the soft magnetic composite powder. Simultaneously, through a first glass powder and granulation process, the powder is transformed into shaped granules suitable for filling and pressing. This reduces the eddy current losses of the subsequent co-fired inductor and improves the flowability and pressing consistency of the granules.

[0032] Step S2 includes: S2.1 Add the oxide insulating precursor to an ethanol-acetone mixed solvent. The amount of the oxide insulating precursor is 0.5-1.5% of the mass of the soft magnetic composite powder. The stirring speed is 300-800 r / min, and the stirring time is 10-30 min. Then add deionized water and a weak acid hydrolysis regulator to control the pH at 4.5-6.5. Pre-hydrolyze at 25-40℃ for 20-60 min to obtain a pre-hydrolyzed oxide precursor solution. The volume ratio of ethanol to acetone in the ethanol-acetone mixed solvent is 3:1-1:3. The weak acid hydrolysis regulator includes at least one of acetic acid, lactic acid, and formic acid.

[0033] The oxide insulating precursor is first dispersed in an ethanol-acetone mixed solvent, and then the environment is adjusted to a weakly acidic state using acetic acid, lactic acid, or formic acid, causing moderate hydrolysis of the oxide insulating precursor. This process enables the oxide insulating precursor to subsequently form a relatively uniform inorganic oxide insulating layer on the surface of the soft magnetic composite powder. This insulating layer increases the resistance between powder particles, reduces eddy current channels between particles during high-frequency operation, and thus reduces core loss.

[0034] S2.2 Add the silicone resin coating component to the pre-hydrolyzed oxide precursor solution and stir at 30–50°C for 20–50 min to obtain a composite insulating solution. Add the composite insulating solution to the soft magnetic composite powder in 3–5 portions. After each addition, stir at 30–60°C for 10–20 min at a stirring speed of 30–80 r / min and a vacuum degree of -0.03–-0.08 MPa. Continue to dry under reduced pressure at 50–80°C for 30–90 min, and then keep at 110–130°C for 1–2 h. Subsequently, the mixture is kept at 150–200℃ for 1–2 hours to obtain a composite insulating coating powder. The silicone resin coating component includes resin raw materials and thermal stress regulating components. The amount of resin raw materials is 1.0–2.5% of the mass of the soft magnetic composite powder, and the amount of thermal stress regulating components is 0.02–0.5% of the mass of the soft magnetic composite powder. The resin raw materials include at least one of MQ silicone resin, methylphenyl silicone resin, methyl silicone resin, and phenyl silicone resin. The thermal stress regulating components include at least one of nano alumina, hexagonal boron nitride, and nano zirconium oxide.

[0035] The addition of silicone resin coating components allows the resin raw material to form a continuous coating layer on the powder surface, compensating for the brittleness and cracking tendency of pure inorganic oxide layers. Methylphenyl silicone resin, methyl silicone resin, or phenyl silicone resin possesses good heat resistance and film-forming properties, providing buffering protection during the pressing process. Nano-alumina, hexagonal boron nitride, or nano-zirconia, as thermal stress regulating components, can improve the crack resistance of the coating layer during heating and cooling processes, reducing microcracks in the insulation layer caused by thermal expansion mismatch.

[0036] S2.3 After cooling the composite insulating coating powder to room temperature, add the first glass powder. The amount of the first glass powder is 0.5 to 1.8% of the mass of the soft magnetic composite powder. Mix at 10 to 30 r / min for 20 to 60 min to obtain the coating powder containing the first glass powder. The first glass powder is zinc borosilicate glass powder.

[0037] After the first glass powder is added to the composite insulating coating powder, it can soften before the second glass powder in the subsequent co-firing process, forming a small amount of glass phase and filling the gaps between the powder particles.

[0038] S2.4. Add a granulation component to the coated powder containing the first glass powder. The granulation component includes a lubricant and a granulation solvent. The amount of lubricant is 0.1-0.3% of the total powder mass, and the amount of granulation solvent is 8-15% of the total powder mass. Stir in a vacuum kneader for 30-90 minutes to obtain a wet granulated material. Place the wet granulated material in an extrusion granulator and granulate it through a 40-80 mesh sieve to obtain wet granules. The granulation component also includes a temporary binder. The amount of lubricant is equal to the amount of soft magnetic composite powder. The amount of granulation solvent is 8-15% of the total mass of the soft magnetic composite powder, and the amount of temporary binder is 1.0-3.0% of the total mass of the soft magnetic composite powder. The lubricant includes at least one of hexagonal boron nitride, zinc stearate, calcium stearate, and microcrystalline wax. The granulation solvent includes at least one of ethanol, acetone, isopropanol, ethyl acetate, and butanone. The temporary binder includes at least one of polyvinyl butyral, epoxy resin, acrylic resin, polyvinyl alcohol, and ethyl cellulose.

[0039] S2.5 Place the wet granules in a hot air circulating oven or vacuum drying oven at 50-70℃ and dry for 1-3 hours to reduce the residual solvent content to below 0.5%. Then, granulate them through a 40-100 mesh sieve to obtain shaped granules.

[0040] Lubricants, granulation solvents, and temporary binders work together to improve powder granulation. Hexagonal boron nitride, zinc stearate, calcium stearate, or microcrystalline wax can reduce friction between powder particles and between powder and mold, reducing the risk of scratching the insulating coating during pressing. Ethanol, acetone, isopropanol, ethyl acetate, or butanone are used to adjust the flowability of the wet mixture, enabling the powder to form uniform wet granules. Polyvinyl butyral, epoxy resin, acrylic resin, polyvinyl alcohol, or ethyl cellulose can improve the strength of both wet and dry granules, making the molded granules less prone to breakage, delamination, or segregation during molding and pressing.

[0041] S3. The copper conductor is placed in an insulating slurry containing the second glass powder for coating treatment. After drying, the copper conductor is embedded in the molding granules and pressed to obtain the inductor blank. The softening temperature of the second glass powder is higher than that of the first glass powder.

[0042] Step S3 includes: S3.1. According to the inductor structure, the copper conductor is processed into a preset shape. The formed copper conductor is then subjected to degreasing, acid pickling activation and drying treatment in sequence. The degreasing treatment is to place the copper conductor in an alkaline degreasing solution for ultrasonic cleaning for 10-20 minutes. The acid pickling activation treatment is to place the copper conductor in a 3-8% dilute sulfuric acid solution for 30-90 seconds. Then, it is rinsed with deionized water and dried with nitrogen gas to obtain a clean copper conductor. S3.2. The second glass powder, dispersant and slurry solvent are mixed and dispersed at a speed of 300-1000 r / min for 1-4 h to obtain an insulating slurry containing the second glass powder. The clean copper conductor is placed in the insulating slurry containing the second glass powder for coating treatment. The immersion time of the copper conductor is 10-60 s and the pulling speed is 1-5 mm / s to obtain a wet film copper conductor. S3.3 After the wet film copper conductor is left to stand at room temperature for 5 to 20 minutes, it is placed in a hot air circulating oven at 80 to 120°C for 20 to 40 minutes to dry, and then placed in a nitrogen-protected oven for step curing. The step curing includes holding at 140 to 160°C for 40 to 80 minutes, holding at 230 to 270°C for 40 to 80 minutes, and holding at 310 to 350°C for 1 to 3 hours to obtain an insulated copper conductor. S3.4 Place the shaped granules and insulated copper conductors into the mold, and then place them in a hot press for segmented pressing. First, pre-press at 50-150MPa and hold for 2-5s, then increase the pressure to 700-1200MPa for main pressing and hold for 5-15s. Then, depressurize at a rate of 50-200MPa / s and place in a vacuum drying oven at 50-80℃ for 30-120min to obtain the inductor green blank.

[0043] The steps of placing the shaped granules and the insulated copper conductor into the mold include: The granules are divided into interface-filled granules and main-filled granules. The particle size of the interface-filled granules is smaller than that of the main-filled granules. First, the interface-filled granules are laid on the bottom of the mold and lightly pressed to flatten it. Then, the insulated copper conductor is placed in the preset position of the mold. Subsequently, the interface-filled granules are filled around the copper conductor, and the main-filled granules are filled on the outside.

[0044] In step S3, the alkaline degreasing solution includes at least one of sodium hydroxide solution, sodium carbonate solution, and sodium metasilicate solution; the second glass powder includes at least one of calcium borosilicate glass powder, barium borosilicate glass powder, aluminosilicate glass powder, calcium aluminum borosilicate glass powder, and barium aluminum borosilicate glass powder; the dispersant includes at least one of phosphate ester dispersant, polycarboxylate dispersant, polyvinylpyrrolidone, nonionic surfactant, and polyacrylate dispersant; and the slurry solvent includes at least one of ethanol, acetone, isopropanol, ethyl acetate, and butanone.

[0045] The use of dispersants and slurry solvents can improve the dispersion uniformity of the second glass powder in the slurry. Phosphate ester dispersants, polycarboxylate dispersants, polyvinylpyrrolidone, nonionic surfactants, or polyacrylate dispersants can reduce glass powder agglomeration; ethanol, acetone, isopropanol, ethyl acetate, or butanone can adjust the slurry fluidity and evaporation rate, making the wet film on the copper conductor surface more uniform and less prone to localized excessive thickness, cracking, or missed coating after drying.

[0046] The stepped curing process gradually removes the solvent from the slurry and ensures that the second glass powder insulation layer has a certain adhesion and strength before pressing. Low-temperature drying first can prevent the wet film from shrinking and cracking rapidly, while medium- and high-temperature curing can enhance the bonding between the glass powder layer and the copper conductor surface, making the insulation layer less likely to be scraped off by powder friction when the copper conductor is subsequently embedded with granules and pressed.

[0047] Dividing the molding granules into interface filler granules and bulk filler granules can improve the filling density around the copper conductor. Smaller interface filler granules can better fill the tiny gaps around the copper conductor, reducing voids and pressure shadows near the conductor; bulk filler granules are used to form the main inductor structure. This improves the density and consistency of the magnetic material around the copper conductor, reducing localized cracks and weak points in the insulation after co-firing.

[0048] Segmented pressing reduces the impact of a single high-pressure pressing on the copper conductor insulation layer and the formed granules. The pre-pressing stage can expel air between the granules and fix the position of the copper conductor, while the main pressing stage increases the green density. Slow pressure release reduces springback stress and minimizes green cracking and copper conductor misalignment. After low-temperature vacuum drying, residual solvent in the inductor green is further removed, which is beneficial for stable glue removal during subsequent co-firing and reduces bulging and voids.

[0049] S4. The inductor blank is placed in a protective atmosphere for segmented co-firing and gradient annealing. The ends of the copper conductor are then ground to form leads. The leads are plated with at least three layers of metal. The part excluding the leads is insulated and encapsulated to obtain a copper-iron co-fired inductor containing an iron-based amorphous alloy.

[0050] Step S4 includes: S4.1 Place the inductor green blank in an atmosphere sintering furnace, introduce a nitrogen-hydrogen mixed atmosphere, with hydrogen gas comprising 5-10% and nitrogen gas as the remainder, at a gas flow rate of 2-5 L / min, and maintain the furnace pressure at 0.105-0.122 MPa. Perform gradient heating to 620-660℃ and hold for 10-30 min, then cool to 420-480℃ at a cooling rate of 0.5-2℃ / min and hold for 30-90 min, then cool to 300-360℃ at a cooling rate of 1-3℃ / min and hold for 20-60 min. Finally, cool to room temperature in the nitrogen-hydrogen mixed atmosphere to obtain the sintered inductor green blank.

[0051] The gradient heating process includes: The temperature is increased from room temperature to 180–220°C at a rate of 2–5°C / min, held for 30–60 min, then increased to 320–420°C at a rate of 2–4°C / min, held for 30–90 min, then increased to 460–530°C at a rate of 2–4°C / min, held for 10–40 min, then increased to 540–570°C at a rate of 3–5°C / min, held for 20–40 min, and finally increased to 620–660°C at a rate of 1–3°C / min.

[0052] S4.2 Grind the ends of the sintered inductor blank until the copper conductor ends are exposed and form leads. Clean and surface activate the leads. The cleaning treatment is ultrasonic cleaning with a weak alkaline cleaning solution for 3-10 minutes. The surface activation treatment is treatment with a 1-5% mass concentration dilute sulfuric acid solution for 10-60 seconds. Then wash with water and dry to obtain the leads to be electroplated. S4.3 Perform at least three layers of metal electroplating on the leads to be electroplated, forming a copper plating layer, a nickel plating layer and a tin plating layer in sequence. The thickness of the copper plating layer is 5-10 μm, the thickness of the nickel plating layer is 2-5 μm, and the thickness of the tin plating layer is 5-10 μm, to obtain an inductor blank with composite metal plating leads. S4.4 First, the lead area of ​​the inductor blank with composite metal plating is shielded. Then, the part except the lead is placed in insulating encapsulating resin for vacuum impregnation. The vacuum degree is -0.05 to -0.10 MPa and the impregnation time is 30 to 60 min. After taking it out, it is cured at 160 to 200℃ for 60 to 90 min, then cooled to 120 to 180℃ and held for 1 to 3 h to obtain a copper-iron co-fired inductor containing iron-based amorphous alloy.

[0053] The insulating encapsulating resin includes at least one of epoxy resin, polyimide resin, polyurethane resin, acrylic resin, phenolic resin, and cyanate ester resin.

[0054] Step S4 involves segmented co-firing and gradient annealing under a nitrogen-hydrogen mixed atmosphere, which gradually removes organic residues from the inductor green blank, softens the first glass powder, and promotes bonding between magnetic powders. Simultaneously, the iron-based amorphous alloy powder undergoes controlled partial crystallization within the range of 620–660°C. Nitrogen primarily serves a protective function, while hydrogen has a certain reducing effect, reducing oxidation of the copper conductor and soft magnetic powder during high-temperature processes, thereby improving the stability of the interface between the magnetic core and the copper conductor after sintering.

[0055] During the gradient heating process, the 180–220℃ and 320–420℃ stages are mainly used to remove temporary binders, granulation solvents, and other organic residues, reducing bulging, voids, and cracking caused by sudden gas release at subsequent high temperatures. The 460–530℃ stage facilitates the short-range migration of segregating elements in the iron-based amorphous alloy powder, providing a foundation for subsequent enrichment at grain boundaries and grain boundary junctions. The 540–570℃ stage promotes the softening of the first glass powder, causing rearrangement and initial bonding between magnetic powder particles. The 620–660℃ stage is used to complete the main co-firing, causing the iron-based amorphous alloy powder to form fine iron nanocrystals and residual amorphous phases, improving magnetic permeability while reducing high-frequency losses.

[0056] Subsequent gradient annealing at 420–480℃ and 300–360℃ gradually releases the internal stress generated during pressing and co-firing, reducing cracks caused by differences in thermal shrinkage between the magnetic sintered body, copper conductor, and glass insulation layer. Simultaneously, the annealing process helps stabilize the iron nanocrystals, residual amorphous phase, and triple-point pinned structure, making it less likely for the iron nanocrystals to coarsen further during subsequent high-temperature thermal cycling, thereby improving the magnetic stability of the inductor.

[0057] End grinding exposes the copper conductor ends embedded in the magnetic sintered body, forming leads that can be electroplated and soldered. The leads are then cleaned and activated using a weak alkaline cleaning solution and dilute sulfuric acid solution to remove grinding dust, oil, and the oxide layer on the copper surface, resulting in more stable adhesion of the subsequent electroplating layer.

[0058] In three-layer metal plating, the copper plating layer improves the conductivity continuity of the pin surface and fills in minor defects after grinding; the nickel plating layer improves oxidation resistance and acts as a barrier layer; and the tin plating layer improves solderability. This allows the inductor to have better terminal reliability during subsequent mounting and soldering processes.

[0059] Insulating encapsulating resins are used to seal the inductor surface, excluding the leads. Epoxy, polyimide, polyurethane, acrylic, phenolic, or cyanate resins can fill the micropores on the sintered body surface, improving the outer surface insulation, resistance to moisture and heat, and corrosion resistance. Vacuum impregnation helps the resin penetrate the surface pores, reducing moisture ingress into the magnetic sintered body, thereby improving the long-term reliability of the inductor.

[0060] This invention proposes a copper-iron co-fired inductor containing an iron-based amorphous alloy, which is manufactured by a method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy. The copper-iron co-fired inductor containing an iron-based amorphous alloy comprises: Carbonyl iron powder is used to improve the saturation magnetic induction intensity and high current carrying capacity of copper-iron co-fired inductors. Crystalline soft magnetic alloy powder is used to construct the magnetic framework of copper-iron co-fired inductors; Iron-based amorphous alloy powder is used to improve the permeability of copper-iron co-fired inductors and reduce high-frequency losses. The first glass powder is used to promote sintering densification; The second glass powder is used to isolate the copper conductor from magnetic materials.

[0061] Example 1: Carbonyl iron powder with a D50 of 4.5 μm, iron-silicon-chromium crystalline soft magnetic alloy powder with a D50 of 18 μm, and iron-based amorphous alloy powder with a D50 of 16 μm were selected, with a mass ratio of carbonyl iron powder, iron-silicon-chromium crystalline soft magnetic alloy powder, and iron-based amorphous alloy powder of 40:30:30. The iron-based amorphous alloy powder was placed in a tube furnace and heated to 460 °C at a rate of 3 °C / min under a nitrogen-hydrogen mixed atmosphere. After holding at this temperature for 20 min, it was cooled to room temperature to obtain heat-treated iron-based amorphous alloy powder. Subsequently, carbonyl iron powder and iron-silicon-chromium crystalline soft magnetic alloy powder were added in batches to heat-treated iron-based amorphous alloy powder and mixed by ball milling under nitrogen protection. The ball milling media were zirconia balls, and the ball-to-material mass ratio was controlled at 5:1. The ball milling media consisted of a mixture of large and small balls, with the large balls having a diameter of 10 mm and the small balls having a diameter of 5 mm. The mass ratio of large to small balls was 3:1. The ball milling speed was controlled at 250 r / min, and the ball milling time was 60 min, resulting in soft magnetic composite powder.

[0062] Tetraethyl orthosilicate was added as an oxide insulating precursor to an ethanol-acetone mixed solvent at a volume ratio of 2:1. The amount of tetraethyl orthosilicate used was 1.0% of the mass of the soft magnetic composite powder. The stirring speed was 500 r / min, and the stirring time was 20 min. Subsequently, deionized water and acetic acid were added to control the pH at 5.5, and the mixture was pre-hydrolyzed at 30 °C for 40 min to obtain a pre-hydrolyzed oxide precursor solution. MQ silicone resin and nano-alumina were added to the pre-hydrolyzed oxide precursor solution, with the amount of MQ silicone resin being 1.5% of the mass of the soft magnetic composite powder and the amount of nano-alumina being 0.2% of the mass of the soft magnetic composite powder. The mixture was stirred at 40 °C for 30 min to obtain a composite insulating solution. The composite insulating solution was added to the soft magnetic composite powder in four portions. After each addition, the powder was stirred at 45°C for 15 minutes at a stirring speed of 50 r / min and a vacuum degree of -0.05 MPa. The powder was then dried under reduced pressure at 65°C for 60 minutes, then kept at 120°C for 1.5 hours, and finally kept at 180°C for 1.5 hours to obtain the composite insulating coated powder.

[0063] After cooling the composite insulating coating powder to room temperature, zinc borosilicate glass powder was added as the first glass powder, with the amount of the first glass powder being 1.2% of the mass of the soft magnetic composite powder. The mixture was stirred at 20 r / min for 40 min to obtain the coating powder containing the first glass powder. Granulation components were added to the coating powder containing the first glass powder, including: a lubricant consisting of microcrystalline wax and hexagonal boron nitride in a mass ratio of 4:3, with the total amount of lubricant being 0.2% of the total mass of the soft magnetic composite powder; a granulation solvent consisting of ethanol and acetone in a volume ratio of 1:1, with the amount of granulation solvent being 10% of the total mass of the soft magnetic composite powder; and a temporary binder consisting of polyvinyl butyral, with the amount being 2.0% of the total mass of the soft magnetic composite powder. The above materials were stirred in a vacuum kneader for 60 min to obtain wet granules, which were then placed in an extrusion granulator and granulated through a 60-mesh sieve to obtain wet granules. The wet granules were placed in a vacuum drying oven at 60°C for 2 hours to reduce the residual solvent content to below 0.5%, and then granulated through an 80-mesh sieve to obtain shaped granules.

[0064] Oxygen-free copper flat wire was processed into a predetermined shape with a thickness of 1.0 mm and a width of 2.0 mm. The formed copper conductor was ultrasonically cleaned in sodium hydroxide solution for 15 min, then treated in a 5% (w / w) dilute sulfuric acid solution for 60 s, followed by rinsing with deionized water and drying with nitrogen gas to obtain a clean copper conductor. Calcium borosilicate glass powder, phosphate ester dispersant, and ethanol were mixed and dispersed, with 2 parts (w / w) of phosphate ester dispersant and 100 parts (w / w) of ethanol per 100 parts (w / w) of calcium borosilicate glass powder. The dispersion speed was 600 r / min, and the dispersion time was 2 h to obtain an insulating slurry containing a second glass powder. The clean copper conductor was then coated in the insulating slurry containing the second glass powder. The immersion time of the copper conductor was 30 s, and the pulling speed was 3 mm / s to obtain a wet film copper conductor.

[0065] After the wet film copper conductor was left to stand at room temperature for 10 minutes, it was dried in a hot air circulating oven at 100℃ for 30 minutes, and then placed in a nitrogen-protected oven for step curing. The step curing included holding at 150℃ for 60 minutes, holding at 250℃ for 60 minutes, and holding at 330℃ for 2 hours to obtain an insulated copper conductor. The shaped granules and the insulated copper conductor were placed in a mold and then placed in a hot press for segmented pressing. First, a pre-pressing pressure of 150MPa was applied and held for 3 seconds, then the pressure was increased to 900MPa for the main pressure and held for 10 seconds. Subsequently, the pressure was released at a rate of 100MPa / s, and then placed in a vacuum drying oven at 60℃ for 60 minutes to obtain the inductor green blank.

[0066] The inductor green blank was placed in an atmosphere sintering furnace, and a nitrogen-hydrogen mixed atmosphere was introduced, with hydrogen comprising 8% and nitrogen as the remainder. The gas flow rate was 3 L / min, and the furnace pressure was maintained at 0.1 MPa. The temperature was first increased from room temperature to 200℃ at a rate of 3℃ / min and held for 45 min; then increased to 380℃ at a rate of 3℃ / min and held for 60 min; then increased to 500℃ at a rate of 3℃ / min and held for 30 min; then increased to 560℃ at a rate of 4℃ / min and held for 30 min; then increased to 640℃ at a rate of 2℃ / min and held for 20 min. Subsequently, the temperature was decreased to 450℃ at a rate of 1℃ / min and held for 60 min; then decreased to 330℃ at a rate of 2℃ / min and held for 40 min. Finally, the furnace was cooled to room temperature in the nitrogen-hydrogen mixed atmosphere to obtain the sintered inductor green blank.

[0067] The ends of the sintered inductor blank were ground until the copper conductor ends were exposed and formed leads. The leads were ultrasonically cleaned for 5 minutes using sodium carbonate solution as a weak alkali cleaning solution, followed by treatment with 3% dilute sulfuric acid solution for 30 seconds, then washed with water and dried to obtain the leads to be electroplated. Copper, nickel, and tin plating were then performed sequentially on the leads to be electroplated, with copper plating thickness of 8 μm, nickel plating thickness of 3 μm, and tin plating thickness of 8 μm, resulting in an inductor blank with composite metal plating leads. The lead area was then masked, and the part excluding the leads was placed in epoxy resin for vacuum impregnation at a vacuum degree of -0.08 MPa for 45 minutes. After removal, it was cured at 180℃ for 70 minutes, then heated to 150℃ and held for 2 hours to obtain a copper-iron co-fired inductor containing an iron-based amorphous alloy.

[0068] Example 2: Example 2 adds an inducing agent treatment to Example 1. The difference lies in that, between steps S1.2 and S1.3, heat-treated iron-based amorphous alloy powder is added to an ethanol-water mixed solvent with a volume ratio of 4:1. Phosphosilicate sol and niobate sol are added as inducing agents, with the amount of phosphosilicate sol being 0.2% of the mass of the iron-based amorphous alloy powder, the amount of niobate sol being 0.1% of the mass of the iron-based amorphous alloy powder, and the total amount of inducing agents being 0.3% of the mass of the iron-based amorphous alloy powder. The mixture is stirred at 55°C for 60 min, and then dried at 80°C for 2 h to obtain the inducing-treated iron-based amorphous alloy powder. Subsequently, a copper-iron co-fired inductor is prepared according to the subsequent steps of Example 1.

[0069] Example 3: Example 3 further adds volatile solvent and interface conditioning agent treatment to Example 2. The difference is that after step S1.3, anhydrous ethanol, silane coupling agent, and polyvinylpyrrolidone are added to the soft magnetic composite powder. The amount of anhydrous ethanol is 4.0% of the mass of the soft magnetic composite powder, the amount of silane coupling agent is 0.05% of the mass of the soft magnetic composite powder, the amount of polyvinylpyrrolidone is 0.05% of the mass of the soft magnetic composite powder, and the total amount of interface conditioning agent is 0.10% of the mass of the soft magnetic composite powder. The mixture is stirred at 30 r / min for 20 min in a mixer, then dried at 60°C for 2 h, then placed in a drum mixer and stirred at 10 r / min for 40 min, and passed through an 80-mesh sieve. Then, the copper-iron co-fired inductor is prepared according to the subsequent steps of Example 2.

[0070] Example 4: Example 4 further adds a partitioned filling step of interface-filling granules and main-filling granules based on Example 3. The difference is that in step S3.4, the molding granules are divided into interface-filling granules and main-filling granules. The interface-filling granules are granules that have passed through an 80-mesh sieve and are retained on a 120-mesh sieve, while the main-filling granules are granules that have passed through a 40-mesh sieve and are retained on an 80-mesh sieve. First, the interface-filling granules are laid on the bottom of the mold and lightly pressed to level it. Then, the insulated copper conductor is placed in the preset position of the mold. Subsequently, the interface-filling granules are filled around the copper conductor, and the main-filling granules are filled on the outside. The remaining steps are the same as in Example 3.

[0071] Example 5: Between steps S1.2 and S1.3, heat-treated iron-based amorphous alloy powder is added to an ethanol-water mixed solvent with a volume ratio of ethanol to water of 4:1. Phosphosilicate sol, borosilicate sol, and molybdate sol are added as composite inducing agents, wherein the amount of phosphosilicate sol is 0.20% of the mass of the iron-based amorphous alloy powder, the amount of borosilicate sol is 0.10% of the mass of the iron-based amorphous alloy powder, the amount of molybdate sol is 0.15% of the mass of the iron-based amorphous alloy powder, and the total amount of composite inducing agents is 0.45% of the mass of the iron-based amorphous alloy powder. The above system is stirred at 60°C for 70 min, and then dried at 85°C for 2 h to obtain composite-induced treated iron-based amorphous alloy powder. Then, following the same mass ratio as in Example 4, carbonyl iron powder, iron-silicon-chromium crystalline soft magnetic alloy powder, and composite-induced treated iron-based amorphous alloy powder are mixed at a ratio of 40:30:30 to obtain soft magnetic composite powder.

[0072] In step S2, the oxide insulating precursor is composed of tetraethyl orthosilicate and aluminum nitrate, wherein the amount of tetraethyl orthosilicate is 0.8% of the mass of the soft magnetic composite powder, and the amount of aluminum nitrate is 0.4% of the mass of the soft magnetic composite powder. In the silicone resin coating component, the resin raw material is MQ silicone resin, and the amount is 1.8% of the mass of the soft magnetic composite powder; the thermal stress regulating component is hexagonal boron nitride and nano-zirconia, wherein the amount of hexagonal boron nitride is 0.25% of the mass of the soft magnetic composite powder, and the amount of nano-zirconia is 0.15% of the mass of the soft magnetic composite powder. The remaining pre-hydrolysis, coating, drying, and curing steps are the same as in Example 4. The first glass powder is zinc borosilicate glass powder, and the total amount of the first glass powder is 1.5% of the mass of the soft magnetic composite powder. In the granulation components, the lubricant is microcrystalline wax and hexagonal boron nitride in a mass ratio of 4:3, and the total amount of lubricant is 0.25% of the total mass of the soft magnetic composite powder; the temporary binder is polyvinyl butyral, and the amount is 2.5% of the total mass of the soft magnetic composite powder; the granulation solvent is ethanol and acetone in a volume ratio of 1:1, and the amount is 12% of the total mass of the soft magnetic composite powder.

[0073] In step S3, the second glass powder is calcium aluminum borosilicate glass powder, the dispersant is a polycarboxylate dispersant, and the slurry solvent is a mixed solvent of ethanol and ethyl acetate, with a volume ratio of ethanol to ethyl acetate of 2:1. After the insulated copper conductor completes step curing, a thin-layer inorganic buffer treatment is performed on its outer surface. This involves rapidly immersing the insulated copper conductor in the inorganic buffer slurry for 5–15 seconds and pulling it up at 2–4 mm / s, followed by drying at 90°C for 20 minutes to obtain an insulated copper conductor with an inorganic buffer transition layer. The inorganic buffer slurry includes calcium aluminum borosilicate glass powder, hexagonal boron nitride, nano-alumina, and ethanol. Based on 100 parts by mass of calcium aluminum borosilicate glass powder, hexagonal boron nitride comprises 5 parts by mass, nano-alumina comprises 3 parts by mass, and ethanol comprises 120 parts by mass. Subsequently, following the method described in Example 4, the same batch of molded granules is divided into interface-filled granules and main-filled granules, and then subjected to zoned filling and segmented pressing.

[0074] In step S4, the main co-firing stage employs a two-stage crystallization-pinning process. The inductor green blank is sequentially heated to 200°C, 380°C, 500°C, and 560°C and held at these temperatures. First, it is heated at 2°C / min to 625°C and held for 10 min, allowing the iron-based amorphous alloy powder to uniformly precipitate fine iron nanocrystals. Then, it is heated to 650°C and held for 15 min, allowing the first glass powder to complete liquid-liquid bonding and promoting the enrichment of phosphorus, silicon, boron, molybdenum, and other components at the grain boundaries and grain boundary junctions of the iron nanocrystals. Afterward, it is cooled at 1°C / min to 450°C and held for 60 min, then cooled at 2°C / min to 330°C and held for 40 min, subsequently cooled to room temperature in the furnace. The other steps are the same as in Example 4.

[0075] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that iron-based amorphous alloy powder is not added. Instead, all 30 parts by mass of iron-based amorphous alloy powder in Example 1 are replaced with iron-silicon-chromium crystalline soft magnetic alloy powder, i.e., carbonyl iron powder is 40 parts by mass and iron-silicon-chromium crystalline soft magnetic alloy powder is 60 parts by mass. The heat treatment step S1.2 for iron-based amorphous alloy powder is no longer performed. The remaining steps are the same as in Example 1.

[0076] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the heat treatment of the iron-based amorphous alloy powder in step S1.2 is omitted. The iron-based amorphous alloy powder with a D50 of 16μm is directly mixed with carbonyl iron powder and iron-silicon-chromium crystalline soft magnetic alloy powder. The remaining powder ratio, coating, granulation, pressing, co-firing, electroplating and encapsulation steps are the same as in Example 1.

[0077] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the oxide insulating precursor and pre-hydrolysis treatment in step S2.1 are omitted, and only MQ silicone resin is used to coat the soft magnetic composite powder. The amount of MQ silicone resin is still 1.5% of the mass of the soft magnetic composite powder. Tetraethyl orthosilicate and nano alumina are not added. The remaining steps are the same as in Example 1.

[0078] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that in step S3.2, calcium borosilicate glass powder is not used as the second glass powder, but zinc borosilicate glass powder, which is the same as the first glass powder, is used as the insulating glass powder on the surface of the copper conductor, so that the softening temperature of the second glass powder is not higher than the softening temperature of the first glass powder. The remaining steps are the same as in Example 1.

[0079] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that the main co-firing peak temperature in step S4.1 is increased from 640°C to 700°C, while the holding time remains 20 min. The remaining gradient heating, cooling, grinding, electroplating and encapsulation steps are the same as in Example 1.

[0080] The copper-iron co-fired inductors prepared in Examples 1 to 5 and Comparative Examples 1 to 5 were all fabricated into samples with the same external dimensions of 7.1 mm × 6.5 mm × 3.0 mm. The copper conductor structure, lead structure, and encapsulation method were kept consistent. Ten samples were prepared for each group, and the test results were averaged to reduce the influence of individual sample compression density, local encapsulation state, and end processing differences on the test results.

[0081] The initial permeability was measured using a precision inductance analyzer at a frequency of 100 kHz and a temperature of 25 °C. During testing, the inductance values ​​of each sample were recorded first, and then the initial permeability was calculated based on the core size and structural parameters. This was used to evaluate the continuity of the magnetic framework in different embodiments and comparative examples, as well as the magnetic response capability of the iron-based amorphous alloy powder after controlled crystallization.

[0082] Core loss was tested using an AC magnetic performance testing system under the following conditions: magnetic flux density 100 mT, frequency 50 kHz, and test temperature 25 °C. This test was used to evaluate the loss level of different samples under high-frequency operating conditions, focusing on the influence of the insulating layer between powder particles, residual amorphous phase, glass bonding state, and the stability of iron nanocrystal grains on high-frequency loss.

[0083] The saturation current was measured using a DC bias current source coupled with an inductance analyzer. During the test, the DC bias current was gradually increased, and the inductance value was recorded in real time. The current at which the inductance value decreased by 30% was taken as the saturation current. This test was used to evaluate the flux carrying capacity of the sample under high-current operating conditions.

[0084] Insulation resistance was tested using an insulation resistance tester. A 500V DC voltage was applied between the copper conductor leads and the outer surface of the magnetic sintered body, and the insulation resistance was recorded after the reading stabilized. Withstand voltage testing was performed using a withstand voltage tester. The voltage was gradually increased between the copper conductor leads and the magnetic sintered body, and the withstand voltage value was recorded when no breakdown or significant leakage abnormality occurred. These two tests are mainly used to evaluate the insulation reliability of the powder composite insulation layer, the copper conductor second glass powder insulation layer, and the external encapsulation layer.

[0085] High-temperature thermal cycling stability was tested using a hot-cold cycling chamber. The cycling conditions ranged from 25°C to 150°C, with each temperature point held for 30 minutes, for a total of 500 cycles. After the thermal cycling was completed, the initial permeability and core loss were tested again, and the permeability retention rate and core loss increase rate after thermal cycling were calculated to evaluate the magnetic performance stability of the sample under repeated high-temperature service conditions.

[0086] Phase structure analysis was performed using X-ray diffraction, with a focus on observing whether obvious boron-iron phase diffraction peaks appeared in the sample. If obvious boron-iron phase was detected, it indicates that unfavorable crystallization occurred in the iron-based amorphous alloy powder during co-firing; if no obvious boron-iron phase was detected, it indicates that the co-firing temperature window can effectively prevent the precipitation of harmful hard and brittle phases.

[0087] The experimental data are shown in Tables 1 and 2.

[0088] Table 1:

[0089] Table 2:

[0090] The results from Example 1 and Comparative Example 1 show that adding iron-based amorphous alloy powder to the soft magnetic powder system improves the permeability and saturation current of the samples, while reducing core loss. This indicates that the iron nanocrystals and residual amorphous phase formed during the co-firing process of the iron-based amorphous alloy powder can improve the magnetic structure and help reduce high-frequency losses. Comparative Example 1 does not contain iron-based amorphous alloy powder, therefore it lacks the improved magnetic properties resulting from this controlled crystallization.

[0091] The results from Example 1 and Comparative Example 2 show that the magnetic properties of the iron-based amorphous alloy powder are more stable after thermal cycling after pre-co-firing heat treatment. Comparative Example 2, which did not undergo this heat treatment, showed that the iron-based amorphous alloy powder was more prone to uneven crystallization during subsequent co-firing, resulting in a more significant decrease in magnetic properties after thermal cycling. This indicates that preheating treatment of the iron-based amorphous alloy powder is beneficial for subsequent uniform crystallization.

[0092] The results from Example 1 and Comparative Example 3 show that the composite insulation layer formed by using an oxide insulating precursor and a silicone resin coating component exhibits better insulation performance and high-frequency loss. Comparative Example 3 only uses silicone resin coating, lacking a stable inorganic oxide insulating layer, resulting in insufficient insulation reliability between powder particles. Consequently, its insulation resistance and withstand voltage performance are poor, and its core loss is also high.

[0093] The results from Example 1 and Comparative Example 4 show that when the softening temperature of the second glass powder is higher than that of the first glass powder, the insulating layer on the surface of the copper conductor can maintain better continuity during co-firing. Comparative Example 4 used the same glass powder as the first glass powder as the insulating layer on the surface of the copper conductor; during co-firing, the glass layer was more prone to softening and flow, and localized copper exposure occurred, leading to a significant decrease in insulation resistance and withstand voltage. This indicates that the difference in softening temperature between the first and second glass powders plays a crucial role in the insulation reliability of the copper-iron co-fired inductor.

[0094] The results from Example 1 and Comparative Example 5 show that controlling the co-firing temperature within a reasonable range can induce favorable partial crystallization of the iron-based amorphous alloy powder and prevent the excessive precipitation of harmful boron-iron phase. In Comparative Example 5, increasing the peak co-firing temperature resulted in the detection of a significant boron-iron phase, along with increased core loss and a marked deterioration in magnetic stability after thermal cycling. This indicates that the co-firing temperature window has a decisive influence on the crystallization products and final magnetic properties of the iron-based amorphous alloy powder.

[0095] The results from Examples 1 to 4 show that the core loss, insulation reliability, and thermal cycling stability of the samples were all improved after the step-by-step superposition of inducing agent treatment, interface conditioning agent treatment, and interface-filling particulate material partitioning steps. Inducing agent treatment helps to improve the grain boundary stability of iron nanocrystals, interface conditioning agent helps to improve powder dispersion uniformity, and partitioning helps to reduce voids and local compression defects around the copper conductor.

[0096] The results of Example 5 show that, within the same batch of basic powder system, the synergistic effects of composite induction treatment, enhanced composite insulation coating, inorganic buffer transition layer on the outer surface of the copper conductor, and the two-stage crystallization-pinning co-firing process further improve the core loss, insulation performance, and thermal cycling stability of the sample. This result indicates that Example 5 did not change the basic preparation route, but rather synergistically optimized key failure locations and key crystallization stages, making the copper-iron co-fired inductor more suitable for long-term use under high-temperature, high-frequency, and high-current conditions.

[0097] Figure 2 The DSC curves for the iron-based amorphous alloy powder used in Examples 1-4 are shown, with a heating rate of 20 K / min. As can be seen from the figure, the iron-based amorphous alloy powder exhibits two distinct exothermic processes. The first crystallization initiation temperature Tx1 is approximately 525℃, and the first crystallization peak temperature Tp1 is approximately 548℃, corresponding to the precipitation of α-Fe nanocrystals in the iron-based amorphous alloy powder. The second crystallization initiation temperature Tx2 is approximately 696℃, and the second crystallization peak temperature Tp2 is approximately 707℃, corresponding to further crystallization at high temperatures and the precipitation of unfavorable phases such as ferroboron. In this application, the co-firing peak temperature is controlled between 620 and 660℃, which is higher than the first crystallization temperature range, enabling controlled partial crystallization of the iron-based amorphous alloy powder and the precipitation of α-Fe nanocrystals; simultaneously, it is lower than the second crystallization initiation temperature of approximately 696℃, thus avoiding the large-scale precipitation of hard and brittle ferroboron phases such as Fe2B and Fe3B.

[0098] Figure 3 The image shows a scanning electron microscope (SEM) image of the iron-based amorphous alloy powder selected in step S1.1 of Example 1, at a magnification of 2000x. The powder particles in the image are generally nearly spherical or near-spherical, with a certain particle size distribution. Larger particles are surrounded by smaller particles, indicating that the iron-based amorphous alloy powder has good flowability and filling properties, making it suitable for ball milling and mixing with carbonyl iron powder and iron-silicon-chromium crystalline soft magnetic alloy powder for subsequent preparation of soft magnetic composite powders.

[0099] Figure 4 The image shows a low-magnification scanning electron microscope (SEM) image of the iron-based amorphous alloy powder selected in step S1.1 of Example 1, with a magnification of 1000x. The image shows that the powder particles are mainly spherical and near-spherical, with a wide particle size distribution, which is beneficial for subsequent powder deposition and pressing.

[0100] Figures 5-10 The image shown is a scanning electron microscope (SEM) image of the soft magnetic composite powder obtained after ball milling and mixing in step S1 of Example 1. Specifically, it corresponds to the powder morphology obtained by ball milling carbonyl iron powder (D50 of 4.5 μm), iron-silicon-chromium crystalline soft magnetic alloy powder (D50 of 18 μm), and iron-based amorphous alloy powder (D50 of 16 μm) in a mass ratio of 40:30:30 under nitrogen protection using zirconia balls. Figures 5 to 7 These are low-magnification images of the soft magnetic composite powder after ball milling and mixing, viewed from different fields of view. Figures 8 to 10 This is a high-magnification image of the corresponding area, used to observe the detailed morphology of the powder particles after ball milling.

[0101] As shown in the figure, the ball-milled soft magnetic composite powder no longer exhibits single, regular spherical particles, but rather a greater number of irregular blocky particles, flaky particles, and fine debris adhering to the surface. The particle surface is significantly roughened, and some particle edges show signs of breakage and peeling. This indicates that under ball milling conditions of 250 r / min and 60 min, the zirconia balls exerted a certain mechanical impact and shearing effect on the powder, achieving relatively thorough mixing among carbonyl iron powder, iron-silicon-chromium crystalline soft magnetic alloy powder, and iron-based amorphous alloy powder. Simultaneously, it caused slight breakage and mechanical activation of the larger particle surfaces.

[0102] The figure illustrates that ball milling helps to break up powder agglomerates, allowing small-diameter carbonyl iron powder and some refined particles to fill the spaces between larger alloy powder particles, thereby improving the mixing uniformity and packing density of the soft magnetic composite powder. At the same time, roughening the powder surface also facilitates the adhesion and coating of the subsequent composite insulating solution on the particle surface, improving the bonding stability of the oxide insulating layer and the silicone resin coating layer.

[0103] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the following claims.

[0104] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy, characterized in that the steps include... include: S1. Mix carbonyl iron powder, crystalline soft magnetic alloy powder and iron-based amorphous alloy powder in a certain proportion to obtain soft magnetic composite powder; Step S1 includes: S1.1 Select carbonyl iron powder with D50 of 3-6μm, crystalline soft magnetic alloy powder with D50 of 10-30μm, and iron-based amorphous alloy powder with D50 of 10-25μm. The mass ratio of carbonyl iron powder: crystalline soft magnetic alloy powder: iron-based amorphous alloy powder is 30-45: 20-35: 15-30. S1.2 Place the iron-based amorphous alloy powder in a tube furnace and heat it to 430-500°C at a rate of 2-5°C / min under a nitrogen-hydrogen mixed atmosphere. Hold the temperature for 10-40 minutes and then cool it to room temperature to obtain heat-treated iron-based amorphous alloy powder. S1.

3. Carbonyl iron powder and crystalline soft magnetic alloy powder are added in batches to heat-treated iron-based amorphous alloy powder. The mixture is ball-milled under nitrogen or argon protection. The ball milling media is zirconia balls. The ball-to-material mass ratio is controlled at 3:1 to 8:

1. The ball milling media is a combination of large and small balls. The diameter of the large balls is 5 to 10 mm and the diameter of the small balls is 2 to 5 mm. The mass ratio of the large balls to the small balls is 1:1 to 3:

1. The ball milling speed is controlled at 150 to 250 r / min and the ball milling time is 30 to 120 min to obtain soft magnetic composite powder. S2. The soft magnetic composite powder is placed in a composite insulating solution for insulating coating, and then the first glass powder is added and granulated to obtain shaped granules. The composite insulating solution includes an oxide insulating precursor and a silicone resin coating component. S3. The copper conductor is placed in an insulating slurry containing the second glass powder for coating treatment. After drying, the copper conductor is embedded in the molding granules and pressed to obtain the inductor blank. The softening temperature of the second glass powder is higher than that of the first glass powder. S4. The inductor blank is placed in a protective atmosphere for segmented co-firing and gradient annealing. The ends of the copper conductor are then ground to form leads. The leads are plated with at least three layers of metal. The part excluding the leads is insulated and encapsulated to obtain a copper-iron co-fired inductor containing an iron-based amorphous alloy.

2. The method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy according to claim 1, characterized in that, Between steps S1.2 and S1.3, step S1 further includes: Heat-treated iron-based amorphous alloy powder was added to an ethanol-water mixture and an inducing agent was added. The mixture was stirred at 40–70°C for 30–90 min and then dried. The inducing agent includes at least one of phosphosilicate sol, borosilicate sol, niobate sol, and molybdate sol, and the amount of the inducing agent is 0.05 to 0.6% of the mass of the iron-based amorphous alloy powder.

3. A method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy according to claim 1 or 2, characterized in that, Following step S1.3, step S1 further includes: Add volatile solvents and interface conditioning agents to the soft magnetic composite powder, stir it in a mixer at 20-50 r / min for 10-30 min, dry it at 50-70℃ for 1-3 h, then place it in a nitrogen-protected drum mixer and stir it at 5-15 r / min for 20-60 min, and pass it through a 60-120 mesh sieve. The volatile solvent includes at least one of anhydrous ethanol, acetone, and isopropanol, and the amount of volatile solvent used is 2 to 6% of the mass of the soft magnetic composite powder. The interface conditioning agent includes at least one of polyvinylpyrrolidone, silane coupling agent, phosphate ester dispersant, and carboxylate dispersant, and the amount of interface conditioning agent used is 0.03 to 0.15% of the mass of the soft magnetic composite powder.

4. A method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy according to claim 1, characterized in that, Step S2 includes: S2.1 Add the oxide insulating precursor to an ethanol-acetone mixed solvent. The amount of oxide insulating precursor is 0.5-1.5% of the mass of the soft magnetic composite powder. The stirring speed is 300-800 r / min and the stirring time is 10-30 min. Then add deionized water and a weak acid hydrolysis regulator to control the pH at 4.5-6.

5. Pre-hydrolyze at 25-40℃ for 20-60 min to obtain a pre-hydrolyzed oxide precursor solution. S2.2 Add the silicone resin coating component to the pre-hydrolyzed oxide precursor solution and stir at 30-50℃ for 20-50 min to obtain a composite insulating solution. Add the composite insulating solution to the soft magnetic composite powder in 3-5 portions. After each addition, stir at 30-60℃ for 10-20 min at a stirring speed of 30-80 r / min and a vacuum degree of -0.03 to -0.08 MPa. Continue to dry under reduced pressure at 50-80℃ for 30-90 min, then keep warm at 110-130℃ for 1-2 h, and then keep warm at 150-200℃ for 1-2 h to obtain the composite insulating coated powder. S2.3 After cooling the composite insulating coating powder to room temperature, add the first glass powder. The amount of the first glass powder is 0.5 to 1.8% of the mass of the soft magnetic composite powder. Mix at 10 to 30 r / min for 20 to 60 min to obtain the coating powder containing the first glass powder. S2.4 Add granulation components to the coated powder containing the first glass powder. The granulation components include a lubricant and a granulation solvent. The amount of lubricant is 0.1-0.3% of the total mass of the powder, and the amount of granulation solvent is 8-15% of the total mass of the powder. Stir in a vacuum kneader for 30-90 minutes to obtain wet granules. Place the wet granules in an extrusion granulator and granulate them through a 40-80 mesh sieve to obtain wet granules. S2.5 Place the wet granules in a hot air circulating oven or vacuum drying oven at 50-70℃ and dry for 1-3 hours to reduce the residual solvent content to below 0.5%. Then, granulate them through a 40-100 mesh sieve to obtain shaped granules.

5. A method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy according to claim 4, characterized in that, In step S2.1, the volume ratio of ethanol to acetone in the ethanol-acetone mixed solvent is 3:1 to 1:3, and the weak acid hydrolysis regulator includes at least one of acetic acid, lactic acid, and formic acid. In step S2.2, the silicone resin coating component includes a resin raw material and a thermal stress regulating component. The amount of the resin raw material is 1.0 to 2.5% of the mass of the soft magnetic composite powder, and the amount of the thermal stress regulating component is 0.02 to 0.5% of the mass of the soft magnetic composite powder. The resin raw material includes at least one of MQ silicone resin, methyl phenyl silicone resin, methyl silicone resin, and phenyl silicone resin. The thermal stress regulating component includes at least one of nano alumina, hexagonal boron nitride, and nano zirconium oxide. In step S2.3, the first glass powder is zinc borosilicate glass powder; In step S2.4, the granulation component further includes a temporary binder, the amount of lubricant is 0.1-0.3% of the total mass of the soft magnetic composite powder, the amount of granulation solvent is 8-15% of the total mass of the soft magnetic composite powder, the amount of temporary binder is 1.0-3.0% of the total mass of the soft magnetic composite powder, the lubricant includes at least one of hexagonal boron nitride, zinc stearate, calcium stearate, and microcrystalline wax, the granulation solvent includes at least one of ethanol, acetone, isopropanol, ethyl acetate, and butanone, and the temporary binder includes at least one of polyvinyl butyral, epoxy resin, acrylic resin, polyvinyl alcohol, and ethyl cellulose.

6. A method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy according to claim 1, characterized in that, Step S3 includes: S3.

1. According to the inductor structure, the copper conductor is processed into a preset shape. The formed copper conductor is then subjected to degreasing, acid pickling activation and drying treatment in sequence. The degreasing treatment is to place the copper conductor in an alkaline degreasing solution for ultrasonic cleaning for 10-20 minutes. The acid pickling activation treatment is to place the copper conductor in a 3-8% dilute sulfuric acid solution for 30-90 seconds. Then, it is rinsed with deionized water and dried with nitrogen gas to obtain a clean copper conductor. S3.

2. The second glass powder, dispersant and slurry solvent are mixed and dispersed at a speed of 300-1000 r / min for 1-4 h to obtain an insulating slurry containing the second glass powder. The clean copper conductor is placed in the insulating slurry containing the second glass powder for coating treatment. The immersion time of the copper conductor is 10-60 s and the pulling speed is 1-5 mm / s to obtain a wet film copper conductor. S3.3 After the wet film copper conductor is left to stand at room temperature for 5 to 20 minutes, it is placed in a hot air circulating oven at 80 to 120°C for 20 to 40 minutes to dry, and then placed in a nitrogen-protected oven for step curing. The step curing includes holding at 140 to 160°C for 40 to 80 minutes, holding at 230 to 270°C for 40 to 80 minutes, and holding at 310 to 350°C for 1 to 3 hours to obtain an insulated copper conductor. S3.4 Place the shaped granules and insulated copper conductors into the mold, and then place them in a hot press for segmented pressing. First, pre-press at 50-150MPa and hold for 2-5s, then increase the pressure to 700-1200MPa for main pressing and hold for 5-15s. Then, depressurize at a rate of 50-200MPa / s and place in a vacuum drying oven at 50-80℃ for 30-120min to obtain the inductor green blank.

7. A method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy according to claim 6, characterized in that, In step S3.4, the step of placing the shaped granules and the insulated copper conductor into the mold includes: The granules are divided into interface-filled granules and main-filled granules. The particle size of the interface-filled granules is smaller than that of the main-filled granules. First, the interface-filled granules are laid on the bottom of the mold and lightly pressed to flatten it. Then, the insulated copper conductor is placed in the preset position of the mold. Subsequently, the interface-filled granules are filled around the copper conductor, and the main-filled granules are filled on the outside.

8. A method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy according to claim 6 or 7, characterized in that, In step S3, the alkaline degreasing solution includes at least one of sodium hydroxide solution, sodium carbonate solution, and sodium metasilicate solution; the second glass powder includes at least one of calcium borosilicate glass powder, barium borosilicate glass powder, aluminosilicate glass powder, calcium aluminum borosilicate glass powder, and barium aluminum borosilicate glass powder; the dispersant includes at least one of phosphate ester dispersant, polycarboxylate dispersant, polyvinylpyrrolidone, nonionic surfactant, and polyacrylate dispersant; and the slurry solvent includes at least one of ethanol, acetone, isopropanol, ethyl acetate, and butanone.

9. A method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy according to claim 1, characterized in that, Step S4 includes: S4.1 Place the inductor green blank in an atmosphere sintering furnace, introduce a nitrogen-hydrogen mixed atmosphere, with hydrogen gas comprising 5-10% and nitrogen gas as the remainder, a gas flow rate of 2-5 L / min, and maintain the furnace pressure at 0.105-0.122 MPa. Perform gradient heating to 620-660℃ and hold for 10-30 min, then cool to 420-480℃ at a cooling rate of 0.5-2℃ / min and hold for 30-90 min, then cool to 300-360℃ at a cooling rate of 1-3℃ / min and hold for 20-60 min. Finally, cool to room temperature in the nitrogen-hydrogen mixed atmosphere to obtain the sintered inductor green blank. S4.2 Grind the ends of the sintered inductor blank until the copper conductor ends are exposed and form leads. Clean and surface activate the leads. The cleaning treatment is ultrasonic cleaning with a weak alkaline cleaning solution for 3-10 minutes. The surface activation treatment is treatment with a 1-5% mass concentration dilute sulfuric acid solution for 10-60 seconds. Then wash with water and dry to obtain the leads to be electroplated. S4.3 Perform at least three layers of metal electroplating on the leads to be electroplated, forming a copper plating layer, a nickel plating layer and a tin plating layer in sequence. The thickness of the copper plating layer is 5-10 μm, the thickness of the nickel plating layer is 2-5 μm, and the thickness of the tin plating layer is 5-10 μm, to obtain an inductor blank with composite metal plating leads. S4.4 First, the lead area of ​​the inductor blank with composite metal plating is shielded. Then, the part except the lead is placed in insulating encapsulating resin for vacuum impregnation. The vacuum degree is -0.05 to -0.10 MPa and the impregnation time is 30 to 60 min. After taking it out, it is cured at 160 to 200℃ for 60 to 90 min, then cooled to 120 to 180℃ and held for 1 to 3 h to obtain a copper-iron co-fired inductor containing iron-based amorphous alloy.

10. A method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy according to claim 9, characterized in that, In step S4.1, the gradient heating step includes: The temperature is increased from room temperature to 180–220°C at a rate of 2–5°C / min, held for 30–60 min, then increased to 320–420°C at a rate of 2–4°C / min, held for 30–90 min, then increased to 460–530°C at a rate of 2–4°C / min, held for 10–40 min, then increased to 540–570°C at a rate of 3–5°C / min, held for 20–40 min, and finally increased to 620–660°C at a rate of 1–3°C / min.

11. A method for preparing a copper-iron co-fired inductor containing an iron-based amorphous alloy according to claim 9 or 10, characterized in that, In step S4, the insulating encapsulating resin includes at least one of epoxy resin, polyimide resin, polyurethane resin, acrylic resin, phenolic resin, and cyanate ester resin.

12. A copper-iron co-fired inductor containing an iron-based amorphous alloy, characterized in that, The copper-iron co-fired inductor, which is made of iron-based amorphous alloy, is manufactured by any one of the preparation methods of claims 1-11. The copper-iron co-fired inductor, which is made of iron-based amorphous alloy, comprises: Carbonyl iron powder is used to improve the saturation magnetic induction intensity and high current carrying capacity of copper-iron co-fired inductors. Crystalline soft magnetic alloy powder is used to construct the magnetic framework of copper-iron co-fired inductors; Iron-based amorphous alloy powder is used to improve the permeability of copper-iron co-fired inductors and reduce high-frequency losses. The first glass powder is used to promote sintering densification; The second glass powder is used to isolate the copper conductor from magnetic materials.

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