A method for preparing a powder for radio frequency inductors

Abstract

The application belongs to the technical field of radio frequency inductance, and discloses a preparation method of a powder material for radio frequency inductance with high saturation, high magnetic permeability and low loss at high frequency, which comprises the following steps: 1) screening alloy type raw powder and ferrite type raw powder to a required particle size respectively; 2) the screened alloy type raw powder is first insulated and then annealed to obtain a first raw powder material, and the ferrite type raw powder is first pre-burnt and crushed before being screened and then deep-cooled to obtain a second raw powder material; 3) after the first and second raw powder materials are fully mixed, a binder is added and uniformly mixed to obtain granulation raw material; 4) the granulation raw material is granulated by an extrusion granulation method to obtain a powder and particle coarse material; and 5) the powder and particle coarse material is screened to obtain the powder material for radio frequency inductance. The powder material has the characteristics of high saturation, high magnetic permeability and low loss under radio frequency conditions, the ferrite powder after deep-cooling is coated around the alloy powder after annealing heat treatment, the insulation performance is high, and the inductance reliability is also improved.

Description

Technical Field

[0001] This invention relates to the field of passive electronic components technology, and more specifically to a method for preparing powder for radio frequency inductors with high saturation, high permeability, and low loss. Background Technology

[0002] The application of wide-bandgap third-generation semiconductor materials, such as silicon carbide and gallium nitride, enables higher switching frequencies in power supply equipment. Passive electronic components such as transformers and inductors used in radio frequency (RF) applications face challenges related to high switching frequencies, including high losses, high EMI, and high heat generation. RF inductors consist of a coil located in the center of the inductor and surrounding powder. This powder, made from raw powder through specific processing, is a fundamental raw material suitable for inductors and has a crucial impact on their performance. The main types of RF inductor powder and their advantages and disadvantages are as follows:

[0003] 1) Ferrite powder: Made from soft magnetic ferrite powder. Advantages: Inexpensive, high permeability, and low loss under RF conditions. Disadvantages: Low saturation magnetic induction intensity Bs, only 0.3-0.5T, resulting in poor saturation of inductors made from it. In addition, inductors produced from ferrite powder require a certain size air gap to be designed, and leakage magnetic flux at the air gap can easily cause EMI.

[0004] 2) Alloy-type powder: Made from soft magnetic alloy powder. Advantages: High saturation magnetic induction intensity Bs, good saturation characteristics of inductance. Disadvantages: Extremely high eddy current loss in the radio frequency high-frequency domain, resulting in severe temperature rise of the product.

[0005] Therefore, there is an urgent need in the field of radio frequency inductors for a powder material with high saturation, high permeability, and low loss at high frequencies. Summary of the Invention

[0006] In summary, the purpose of this invention is to solve the aforementioned drawbacks of existing ferrite powder or alloy powder inductors at high frequencies, which lead to easy magnetic leakage, EMI, high eddy current loss, and severe product temperature rise. The invention provides a manufacturing process for RF inductor powder that combines the advantages of both ferrite powder and alloy powder, and exhibits high saturation, high permeability, and low loss characteristics at high frequencies.

[0007] To address the shortcomings of the technology proposed in this invention, the adopted technical solution is a method for preparing powder for radio frequency inductors, characterized by comprising the following steps:

[0008] Step 1: Sieve the alloy powder and ferrite powder to the required particle size respectively; the alloy powder is sieved to select a particle size D50 of 1-8 μm and a D90 of 0.5-15 μm; the ferrite powder is pre-calcined and crushed before sieving, and then sieved to select a particle size D50 of 0.5-3 μm and a D90 of 1.0-5 μm.

[0009] Step 2: The sieved alloy powder is insulated using at least one of the following methods: phosphating, chromate passivation, water glass coating, and SiO2 coating. Then, the insulated alloy powder is subjected to annealing heat treatment in a non-oxidizing atmosphere, which involves heating, holding, and then slowly cooling in the furnace to obtain the first raw powder. The holding temperature during the annealing heat treatment is 350℃~950℃. The sieved ferrite powder is cryogenically treated at -60℃~-200℃ for 0.5~24h to obtain the second raw powder.

[0010] Step 3: Place 60% to 98% of the first raw powder and 2% to 40% of the second raw powder in a mixer and stir for 0.5 to 48 hours to mix thoroughly. Then add 0.5% to 4% of the binder to the uniformly mixed raw powder and continue stirring until fully mixed to obtain the granulation raw material.

[0011] Step 4: Granulate the raw material using extrusion granulation to obtain coarse powder.

[0012] Step 5: The obtained powder material is sieved to remove coarse particles of 60-100 mesh and fine particles of 200-400 mesh, thereby obtaining the RF inductor powder material.

[0013] Furthermore, the sieving in step 1 adopts one of the following methods: air classification, vibrating sieving, and sedimentation. The sieving of alloy raw powder and ferrite raw powder can adopt the same method or different methods.

[0014] Furthermore, the alloy-type raw powder includes one or more of the following: carbonyl iron powder, iron-silicon powder, iron-nickel powder, iron-cobalt powder, iron-silicon-aluminum powder, amorphous powder, and nanocrystalline powder.

[0015] Furthermore, the ferrite raw powder includes one or more of manganese-zinc ferrite powder and nickel-zinc ferrite powder.

[0016] Furthermore, the non-oxidizing atmosphere in step 2 includes a vacuum or nitrogen atmosphere, an argon atmosphere, a hydrogen atmosphere, and a mixture of two or more of the above atmospheres.

[0017] Furthermore, the adhesive in step 3 includes one or more of epoxy resin, silicone resin, unsaturated polyester resin, and phenolic resin.

[0018] Furthermore, in step 4, the extrusion granulation method uses a sieve with a mesh size of 40 to 120 to extrude the raw material for granulation.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. A reasonable combination of particle sizes between alloy-based raw powder and ferrite-based raw powder can result in a uniform and reasonable air gap distribution in the powder, leading to higher powder saturation.

[0021] 2. Ferrite-based raw powders have high resistivity. When distributed around alloy raw powders, they can prevent the formation of eddy current channels between the alloy raw powders, thus greatly reducing the eddy current loss of the powder. The loss of the powder consists of hysteresis loss, eddy current loss, and residual loss. Under radio frequency conditions, eddy current loss is dominant, so the total loss of the powder is also greatly reduced.

[0022] 3. Ferrite powders have high magnetic permeability, and small-particle-size ferrite powders can both coat the alloy powder to act as "magnetic channels" and fill the gaps between the powders, resulting in higher powder density and higher magnetic permeability.

[0023] 4. The cryogenically treated ferrite powder is distributed around the annealed heat-treated alloy powder, resulting in high insulation performance and good temperature resistance, and improved inductor reliability. Attached Figure Description

[0024] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0025] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1

[0027] A method for preparing powder for radio frequency inductors specifically includes the following steps:

[0028] Step 1: Ferrosilicon powder, FeSiBCrC amorphous powder, and manganese-zinc ferrite powder were sieved using an air classifier. For ferrosilicon powder, the selected particle sizes were D50 of 3.0 μm and D90 of 5.0 μm. For FeSiBCrC amorphous powder, the selected particle sizes were D50 of 4.0 μm and D90 of 6.0 μm. Before sieving, the manganese-zinc ferrite powder underwent pre-calcination and crushing. Then, the pre-calcined and crushed manganese-zinc ferrite powder was sieved using an air classifier, selecting particle sizes D50 of 1.5 μm and D90 of 2.5 μm.

[0029] Step 2: According to weight parts, take 65 parts of sieved iron-silicon powder, 30 parts of FeSiBCrC amorphous powder, and 5 parts of manganese-zinc ferrite powder. First, mix the 65 parts of iron-silicon powder and the 30 parts of FeSiBCrC amorphous powder. Then, add 2% phosphoric acid, 1% SiO2 powder, and 15% ethanol by weight to the iron-silicon / amorphous mixed powder. Continue stirring until the ethanol completely evaporates, completing the phosphating / SiO2 coating insulation treatment of the alloy mixed powder. Next, anneal the alloy mixed powder after insulation treatment at 430℃ in a non-oxidizing atmosphere for 1 hour, with a heating rate of 10℃ / min, under a nitrogen protective atmosphere to obtain the first raw powder. Place 5 parts of manganese-zinc ferrite powder in a sealed container filled with dry ice (-78.5℃) for 1 to 6 hours to cool the manganese-zinc ferrite powder to below -60℃ to obtain the second raw powder.

[0030] Step 3: Place the first raw powder and the second raw powder obtained in Step 2 into a mixer and stir for 4-6 hours to ensure they are fully mixed. Then, add 1.5% by weight of epoxy resin binder to the mixed raw powder and continue stirring until fully mixed to obtain the granulated raw material.

[0031] Step 4: The raw material obtained in Step 3 is extruded and granulated through a 40-120 mesh sieve to obtain coarse powder.

[0032] Step 5: The coarse powder obtained in Step 4 is sieved to remove coarse particles of +80 mesh and fine powder of -300 mesh, thus obtaining the RF inductor powder of Example 1.

[0033] Example 2

[0034] A method for preparing powder for radio frequency inductors specifically includes the following steps:

[0035] Step 1: Ferrosilicon powder and FeSiBCrC amorphous powder were sieved using a vibrating sieve method. The selected particle sizes for ferrosilicon powder were D50 of 2.0 μm and D90 of 7.5 μm, while those for FeSiBCrC amorphous powder were D50 of 6.5 μm and D90 of 14.5 μm. Manganese-zinc ferrite powder was pre-calcined and crushed before sieving. Then, the pre-calcined and crushed manganese-zinc ferrite powder was sieved using an air classifier method, selecting particle sizes D50 of 2.0 μm and D90 of 4.5 μm.

[0036] Step 2: According to weight parts, take 65 parts of the sieved iron-silicon powder, 30 parts of FeSiBCrC amorphous powder, and 5 parts of manganese-zinc ferrite powder. First, mix the 65 parts of iron-silicon powder and the 30 parts of FeSiBCrC amorphous powder. Then, add 4% by weight of a sodium silicate solution with a concentration of 35wt% to 40wt% to the iron-silicon / amorphous mixed powder. Heat while stirring at 65℃ to 120℃ until the alloy mixed powder is completely dry, completing its water glass coating insulation treatment. Next, anneal the insulating alloy mixed powder at 650℃ in a non-oxidizing atmosphere for 2 hours, with a heating rate of 15℃ / min, under a nitrogen and argon mixed atmosphere to obtain the first raw powder. Five portions of manganese-zinc ferrite powder were placed in a heat exchange container, and liquid nitrogen (-196℃) was continuously flowed through the heat exchange container for 6 to 12 hours. The deep cryogenic treatment of the manganese-zinc ferrite powder in the heat exchange container was achieved by utilizing the heat absorption of liquid nitrogen vaporization, so that the manganese-zinc ferrite powder was cooled to below -130℃ to obtain the second raw powder.

[0037] Step 3: Place the first raw powder and the second raw powder obtained in Step 2 into a mixer and stir for 6 to 12 hours to ensure they are fully mixed. Then, add 3.5% by weight of unsaturated polyester resin binder to the mixed raw powder and continue stirring until fully mixed to obtain the granulation raw material.

[0038] Step 4: The raw material obtained in Step 3 is extruded and granulated through a 40-120 mesh sieve to obtain coarse powder.

[0039] Step 5: The coarse powder obtained in Step 4 is sieved to remove coarse particles of +60 mesh and fine powder of -200 mesh, and the powder for radio frequency inductors of Example 1 is obtained.

[0040] Example 3

[0041] A method for preparing powder for radio frequency inductors specifically includes the following steps:

[0042] Step 1: Carbonyl iron powder, FeNiPB amorphous powder, and nickel-zinc ferrite powder were sieved using an air classifier. The carbonyl iron powder was sieved to a particle size D50 of 6.5 μm and a D90 of 12.5 μm, while the FeNiPB amorphous powder was sieved to a particle size D50 of 2.5 μm and a D90 of 7.5 μm. The nickel-zinc ferrite powder was pre-calcined and crushed before sieving, and then sieved using an air classifier to select a particle size D50 of 1.5 μm and a D90 of 2.5 μm.

[0043] Step 2: According to weight parts, take 20 parts of sieved carbonyl iron powder, 45 parts of FeNiPB amorphous powder, and 35 parts of nickel-zinc ferrite powder respectively. First, mix 45 parts of FeNiPB amorphous powder and 20 parts of carbonyl iron powder. Then, add 2% phosphoric acid, 1% SiO2 powder, and 15% ethanol by weight to the carbonyl iron / amorphous mixed powder. Continue stirring until the ethanol completely evaporates, completing the phosphating / SiO2 coating insulation treatment of the alloy mixed powder. Next, anneal the insulating alloy mixed powder at 430℃ in a non-oxidizing atmosphere for 1 hour, with a heating rate of 10℃ / min, under a nitrogen atmosphere, to obtain the first raw powder. Place 35 parts of nickel-zinc ferrite powder in a sealed container filled with dry ice (-78.5℃) for 1 hour to 6 hours to cool the nickel-zinc ferrite powder to below -60℃ to obtain the second raw powder.

[0044] Step 3: Place the first raw powder and the second raw powder obtained in Step 2 into a mixer and stir for 4 to 6 hours to ensure they are fully mixed. Then, add 1.5% by weight of epoxy resin binder to the mixed raw powder and continue stirring until fully mixed to obtain the granulated raw material.

[0045] Step 4: The raw material obtained in Step 3 is extruded and granulated through a 40-120 mesh sieve to obtain coarse powder.

[0046] Step 5: The coarse powder obtained in Step 4 is sieved to remove coarse particles of +80 mesh and fine powder of -300 mesh, and the powder for radio frequency inductors of Example 1 is obtained.

[0047] Example 4

[0048] A method for preparing powder for radio frequency inductors specifically includes the following steps:

[0049] Step 1: Carbonyl iron powder and FeNiPB amorphous powder were sieved using a vibrating sieve method. The carbonyl iron powder was sieved to a particle size D50 of 2.0 μm and D90 of 7.5 μm, while the FeNiPB amorphous powder was sieved to a particle size D50 of 6.5 μm and D90 of 14.5 μm. Nickel-zinc ferrite powder was pre-calcined and crushed before sieving, and then sieved using an airflow classification method to select a particle size D50 of 2.0 μm and D90 of 4.5 μm.

[0050] Step 2: According to weight parts, take 30 parts of sieved carbonyl iron powder, 65 parts of FeNiPB amorphous powder, and 5 parts of nickel-zinc ferrite powder respectively. First, mix the 65 parts of FeNiPB amorphous powder and the 30 parts of carbonyl iron powder. Then, add 4% by weight of sodium silicate solution with a concentration of 35wt% to 40wt% to the carbonyl iron / amorphous mixed powder. Heat while stirring at 65℃ to 120℃ until the alloy mixed powder is completely dry, completing its water glass coating insulation treatment. Next, anneal the insulating alloy mixed powder at 650℃ in a non-oxidizing atmosphere for 2 hours, with a heating rate of 15℃ / min, under a nitrogen and argon mixed atmosphere to obtain the first raw powder. Five portions of nickel-zinc ferrite powder were placed in a heat exchange container, and liquid nitrogen (-196℃) was continuously flowed through the heat exchange container for 6 to 12 hours. The deep cryogenic treatment of the nickel-zinc ferrite powder in the heat exchange container was achieved by utilizing the heat absorption of liquid nitrogen vaporization, so that the nickel-zinc ferrite powder was cooled to below -130℃ to obtain the second raw powder.

[0051] Step 3: Place the first raw powder and the second raw powder obtained in Step 2 into a mixer and stir for 6 to 12 hours to ensure they are fully mixed. Then, add 3.5% by weight of unsaturated polyester resin binder to the mixed raw powder and continue stirring until fully mixed to obtain the granulation raw material.

[0052] Step 4: The raw material obtained in Step 3 is extruded and granulated through a 40-120 mesh sieve to obtain coarse powder.

[0053] Step 5: The coarse powder obtained in Step 4 is sieved to remove coarse particles of +60 mesh and fine powder of -200 mesh, and the powder for radio frequency inductors of Example 1 is obtained.

[0054] Example 5

[0055] A method for preparing powder for radio frequency inductors specifically includes the following steps:

[0056] Step 1: The FeSiBCrC amorphous powder and manganese-zinc ferrite powder were sieved using an air classifier. For the FeSiBCrC amorphous powder, the particle size D50 was selected as 2.5 μm and D90 as 4.0 μm. The manganese-zinc ferrite powder was pre-calcined and crushed before sieving, and then sieved using an air classifier to select particle sizes D50 as 1.0 μm and D90 as 2.0 μm.

[0057] Step 2: According to weight parts, take 100 parts of the sieved FeSiBCrC amorphous powder and 5 parts of manganese-zinc ferrite powder respectively. Add 2% SiO2 powder and 15% ethanol by weight to 100 parts of FeSiBCrC amorphous powder, and continue stirring until the ethanol completely evaporates to complete the SiO2 coating insulation treatment of the amorphous powder. Then, anneal the amorphous powder after insulation treatment in a non-oxidizing atmosphere at 410℃ for 1 hour, with a heating rate of 10℃ / min, and a nitrogen atmosphere to obtain the first raw powder. Place 5 parts of manganese-zinc ferrite powder in a sealed container filled with dry ice (-78.5℃) for 1 to 6 hours to cool the manganese-zinc ferrite powder to below -60℃ to obtain the second raw powder.

[0058] Step 3: Place the first raw powder and the second raw powder obtained in Step 2 into a mixer and stir for 2-4 hours to ensure they are fully mixed. Then add 1.5% by weight of epoxy resin binder to the mixed raw powder and continue stirring until fully mixed to obtain the granulated raw material.

[0059] Step 4: The raw material obtained in Step 3 is extruded and granulated through a 40-120 mesh sieve to obtain coarse powder.

[0060] Step 5: The coarse powder obtained in Step 4 is sieved to remove coarse particles of +80 mesh and fine powder of -300 mesh, thus obtaining the RF inductor powder of Example 1.

[0061] Example 6

[0062] A method for preparing powder for radio frequency inductors specifically includes the following steps:

[0063] Step 1: FeNiPB amorphous powder, manganese-zinc ferrite powder, and nickel-zinc ferrite powder were sieved using an air classifier. For the FeNiPB amorphous powder, the particle size D50 was selected to be 2.5 μm and D90 to be 4.0 μm. Before sieving, the manganese-zinc ferrite powder and nickel-zinc ferrite powder were pre-calcined and crushed, respectively. Then, the pre-calcined and crushed manganese-zinc ferrite powder and nickel-zinc ferrite powder were sieved using an air classifier. For both manganese-zinc ferrite powder and nickel-zinc ferrite powder, the particle size D50 was selected to be 1.0 μm and D90 to be 2.0 μm.

[0064] Step 2: According to weight parts, take 95 parts of the sieved FeNiPB amorphous powder, 2 parts of manganese-zinc ferrite powder, and 3 parts of nickel-zinc ferrite powder respectively. Add 2% by weight of sodium silicate solution with a concentration of 35wt% to 40wt% to the 95 parts of FeNiPB amorphous powder. Heat while stirring at 65℃ to 120℃ until the amorphous powder is completely dry, completing its water glass coating insulation treatment. Then, anneal the insulated amorphous powder at 620℃ in a non-oxidizing atmosphere for 3 hours, with a heating rate of 15℃ / min, under a protective atmosphere of nitrogen and hydrogen mixture, thereby obtaining the first raw powder. Two parts of manganese-zinc ferrite powder and three parts of nickel-zinc ferrite powder were thoroughly mixed and placed in a heat exchange container. Liquid nitrogen (-196℃) was continuously flowed through the heat exchange container for 2 to 6 hours. The deep cryogenic treatment of the manganese-zinc ferrite powder and nickel-zinc ferrite powder in the heat exchange container was achieved by utilizing the heat absorption of liquid nitrogen vaporization. The ferrite mixed powder was cooled to below -130℃ to obtain the second raw powder.

[0065] Step 3: Place the first raw powder and the second raw powder obtained in Step 2 in a mixer and stir for 24-48 hours to ensure they are fully mixed. Then, add 1.5% by weight of epoxy resin binder to the mixed raw powder and continue stirring until fully mixed to obtain the granulated raw material.

[0066] Step 4: The raw material obtained in Step 3 is extruded and granulated through a 40-120 mesh sieve to obtain coarse powder.

[0067] Step 5: The coarse powder obtained in Step 4 is sieved to remove coarse particles of +100 mesh and fine powder of -350 mesh, to obtain the RF inductor powder of Example 1.

[0068] Comparative Example 1

[0069] Take 100 parts of unscreened iron-silicon powder with a D50 of 10.0 μm and a D90 of 18.0 μm and FeSiBCrC amorphous powder, add 2% by weight of SiO2 powder and 15% by weight of ethanol to the iron-silicon / amorphous mixed powder and stir until the ethanol is completely evaporated, thus completing the SiO2 coating insulation treatment of the alloy mixed powder. Then, add 1.5% by weight of epoxy resin binder to the alloy mixed powder after insulation treatment and continue stirring. After mixing, extrude and granulate the mixture through a 40-120 mesh sieve to obtain coarse powder. Then, sieve the obtained coarse powder to remove coarse particles of +80 mesh and fine powder of -300 mesh to obtain the RF inductor powder of Comparative Example 1.

[0070] Comparative Example 2

[0071] One hundred parts of iron-silicon powder with D50 of 2.5μm and D90 of 4.0μm and FeSiBCrC amorphous powder were separated by air classification. They were added to 2% by weight of SiO2 powder and 15% by weight of ethanol iron-silicon / amorphous mixed powder and stirred until the ethanol was completely evaporated, thus completing the SiO2 coating insulation treatment of the alloy mixed powder. Then, the alloy mixed powder after insulation treatment was subjected to annealing heat treatment. Then, 5 portions of pre-fired, crushed manganese-zinc ferrite with D50 of 1.0 μm and D90 of 2.0 μm were mixed with alloy powder that had undergone annealing heat treatment. After thorough mixing, 1.5% by weight of epoxy resin binder was added. The mixture was stirred and mixed continuously, and then extruded through a 40-120 mesh sieve to obtain coarse powder. The obtained coarse powder was then sieved to remove coarse particles of +80 mesh and fine powder of -300 mesh, thus obtaining the RF inductor powder of Comparative Example 2.

[0072] The following table describes the implementation methods and performance of the powder samples of the above six embodiments and two comparative examples.

[0073]

[0074] Table 1: Powder composition ratio and sieve particle size of Examples 1-6.

[0075]

[0076]

[0077] Table 2: Powder composition ratio and sieve particle size of Comparative Examples 1-2.

[0078] Evaluation Project Permeability μe@13.56MHz L decrease rate @100Oe Pcv@13.56MHz, 10mT Example 1 23.66 -8.80％ 420.65mW.cm-3 Example 2 24.78 -9.06％ 362.65mW.cm-3 Example 3 19.13 -8.47％ 412.30mW.cm-3 Example 4 20.65 -8.36％ 398.85mW.cm-3 Example 5 18.17 -5.32％ 326.51mW.cm-3 Example 6 19.56 -6.55％ 355.45mW.cm-3 Comparative Example 1 16.36 -9.25％ 1086.32mW.cm-3 Comparative Example 2 15.24 -8.11％ 879.23 mW·cm⁻³

[0079] Table 3: Performance Evaluation Table of Example and Comparative Samples.

[0080] The data in the table above intuitively shows the formulation components and particle size sieving range of the powders in each embodiment of the present invention. Compared with the comparative sample, the RF inductor powders prepared using the technical solutions of each embodiment of the present invention all have excellent performance. In particular, it can be seen from the combination of Example 1 and Example 2 in Tables 1 and 3 that when the selection of alloy-type raw powder and ferrite-type raw powder is the same, the sieving particle size is more concentrated, the removal of large particles and the finer separation are more thorough, and the powder prepared by Example 2, which uses liquid nitrogen for deep cryogenic treatment, has better performance than the powder prepared by Example 1.

[0081] In summary, this invention significantly improves the performance indicators of the granulation raw materials by combining alloy-based and ferrite-based raw powders, sieving the powder particles, and combining the insulating annealing process of the alloy-based raw powder with the cryogenic treatment process of the ferrite-based raw powder. After extrusion granulation, large particles and fine powder in the coarse powder are removed by sieving. This allows the RF inductor powder produced by this invention to have the advantages of both alloy-based and ferrite-based powders. It also exhibits excellent performance with high saturation, high permeability, and low loss when used at high switching frequencies, making it suitable for a wide range of applications. Furthermore, the production process is simple and low-cost.

[0082] The above embodiments are merely for illustrating the technical solutions of the present invention and are not intended to limit the implementation of the present invention. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the present invention.

Claims

1. A method for preparing powder for radio frequency inductors, characterized in that, Includes the following steps: Step 1: Sieve the alloy powder and ferrite powder to the required particle size respectively; the alloy powder is sieved to select a particle size D50 of 1-8 μm and a D90 of 0.5-15 μm; the ferrite powder is pre-calcined and crushed before sieving, and then sieved to select a particle size D50 of 0.5-3 μm and a D90 of 1.0-5 μm. The alloy-type raw powder includes one or more of the following: carbonyl iron powder, iron-silicon powder, iron-nickel powder, iron-cobalt powder, iron-silicon-aluminum powder, amorphous powder, and nanocrystalline powder; The ferrite raw powder includes one or more of manganese-zinc ferrite powder and nickel-zinc ferrite powder. Step 2: The alloy raw powder sieved out is insulated using at least one of the following methods: phosphating, chromate passivation, water glass coating, and SiO2 coating. Then, the insulated alloy raw powder is subjected to annealing heat treatment in a non-oxidizing atmosphere, which involves heating, holding, and then slowly cooling in the furnace to obtain the first raw powder. The holding temperature during the annealing heat treatment is 350℃~950℃. The ferrite raw powder that has been screened is cryogenically treated at -60℃ to -200℃ for 0.5 to 24 hours to obtain the second raw powder. Step 3: Place 60% to 98% of the first raw powder and 2% to 40% of the second raw powder in a mixer and stir for 0.5 to 48 hours to fully mix. Then add 0.5% to 4% of the binder to the uniformly mixed raw powder and continue stirring until fully mixed to obtain the granulation raw material. Step 4: Granulate the raw material using extrusion granulation to obtain coarse powder. Step 5: The obtained powder material is sieved to remove coarse particles of 60-100 mesh and fine particles of 200-400 mesh, thereby obtaining the RF inductor powder material.

2. The method for preparing a powder for radio frequency inductors according to claim 1, characterized in that, The sieving in step 1 adopts one of the following methods: air classification, vibrating sieving, and sedimentation. The sieving of alloy raw powder and ferrite raw powder can adopt the same method or different methods.

3. The method for preparing a powder for radio frequency inductors according to claim 1, characterized in that, The non-oxidizing atmosphere in step 2 includes a vacuum or nitrogen atmosphere, an argon atmosphere, a hydrogen atmosphere, and a mixture of two or more of the above atmospheres.

4. The method for preparing a powder for radio frequency inductors according to claim 1, characterized in that, The adhesive in step 3 includes one or more of epoxy resin, silicone resin, unsaturated polyester resin and phenolic resin.

5. The method for preparing a powder for radio frequency inductors according to claim 1, characterized in that, In step 4, the extrusion granulation method uses a sieve with a mesh size of 40 to 120 to extrude the raw material for granulation.

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