A low-loss inductor core and its preparation method

Abstract

The present invention belongs to the technical field of soft magnetic materials, and specifically relates to a low-loss inductor core and a preparation method thereof. The preparation method comprises the following preparation steps: (1) uniformly mixing vinyl silicone oil, hydrogenated silicone oil, platinum complex catalyst, inhibitor, and low-melting-point glass powder at room temperature to obtain an insulating coating adhesive; (2) uniformly mixing the obtained insulating coating adhesive with ferrite magnetic powder, first performing mold curing at a temperature of 60 to 100°C and a pressure of 200 to 500 MPa, and then heating to 500 to 800°C for sintering to obtain a low-loss inductor core. The present invention uses an addition-type curable organic silicone resin to bond the ferrite magnetic powder, can be cured and formed at a lower pressure, and combined with the filling effect of the high-temperature sintered low-melting-point glass, can significantly improve the insulating coating effect and the density of the magnetic core after mold curing, thereby reducing losses.

Description

Technical Field

[0001] The present invention belongs to the technical field of soft magnetic materials, and in particular relates to a low-loss inductor core and a preparation method thereof. Background Art

[0002] Inductor cores primarily consist of ferrite cores, iron alloy cores, and amorphous nanocrystalline soft magnetic alloy cores. These soft magnetic materials are made by compressing and sintering magnetic powders with an insulating coating. Their excellent magnetic properties have led to their widespread use in applications such as wireless communication sensors, transformers, and automobiles. However, with the development of modern society, the demand for high-frequency electronic devices has further increased, making low-loss soft magnetic composite materials a research hotspot.

[0003] Patent CN 114360884 A discloses a method for preparing a high-induction, low-loss gradient nanocrystalline magnetic powder core. The method involves treating Fe-based amorphous alloy powder with a discharge plasma to nanocrystallize the surface layer of the amorphous powder. The powder is then pressed and shaped after adding a coating agent and lubricant. Finally, the powder is sintered at a temperature above the crystallization temperature of the Fe-based amorphous alloy powder. This allows the nanocrystals on the powder surface to continue growing, while the amorphous particles within the powder nanocrystallize, forming a gradient in grain size. This results in a high-induction, low-loss gradient nanocrystalline magnetic powder core with large outer grains and small inner grains. Patent CN 116598117 A discloses a method for preparing a high-induction, low-loss amorphous / nanocrystalline magnetic powder core based on a magnetically conductive insulating shell core-shell functional unit. The method involves coating a micron-sized Fe-based amorphous / nanocrystalline powder core with an insulating and magnetically conductive shell to form a magnetically conductive insulating shell functional unit. Combining the pressing and sintering processes, the core produces a high-induction, low-loss composite magnetic powder core. Although the above-mentioned existing technology can achieve good insulation coating effect to reduce eddy current loss, the organic resin and organic lubricant used in its insulation coating will produce excessive air gap during the high-temperature sintering process, resulting in a decrease in the magnetic permeability of the magnetic core and an increase in hysteresis loss, thereby reducing the overall magnetic performance. Summary of the Invention

[0004] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a method for preparing a low-loss inductor core.

[0005] Another object of the present invention is to provide a low-loss inductor core prepared by the above method.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for preparing a low-loss inductor core comprises the following steps:

[0008] (1) Preparation of insulation coating adhesive:

[0009] Vinyl silicone oil, hydrogen-containing silicone oil, platinum complex catalyst, inhibitor and low-melting-point glass powder are uniformly mixed at room temperature to obtain an insulating coating adhesive;

[0010] (2) Preparation of low-loss inductor core:

[0011] The obtained insulating coating adhesive is evenly mixed with ferrite magnetic powder, first molded and cured at a temperature of 60-100° C. and a pressure of 200-500 MPa, and then heated to 500-800° C. for sintering to obtain a low-loss inductor magnetic core.

[0012] Furthermore, the vinyl silicone oil in step (1) is a vinyl silicone oil with a viscosity of 100 to 2000 mPa·s and a vinyl content of 1% to 10%.

[0013] Furthermore, the hydrogen-containing silicone oil in step (1) has a viscosity of 100 to 2000 mPa·s and a hydrogen content of 0.2% to 1.5%.

[0014] Further preferably, the mass ratio of the vinyl silicone oil to the hydrogen-containing silicone oil is 1:0.1-0.6.

[0015] Furthermore, the amount of the platinum complex catalyst added in step (1) is 0.005% to 0.02% of the total mass of the vinyl silicone oil and the hydrogen-containing silicone oil.

[0016] Furthermore, the inhibitor in step (1) is an acetylene alcohol inhibitor, and the amount of the acetylene alcohol inhibitor added is 0.05% to 0.2% of the total mass of the vinyl silicone oil and the hydrogen-containing silicone oil.

[0017] Furthermore, the low-melting-point glass powder in step (1) has a particle size of 1 to 10 μm and a melting point of 300 to 600° C.

[0018] Further preferably, the added amount of the low-melting-point glass powder is 5% to 40% of the total mass of the vinyl silicone oil and the hydrogen-containing silicone oil.

[0019] The relative addition amount of the low-melting-point glass powder of the present invention has a significant impact on the strength and loss of the obtained inductor core. When the addition amount of the low-melting-point glass powder is too low, the air gap generated by the high-temperature sintering of the insulating coating adhesive cannot be effectively filled, resulting in an increase in hysteresis loss. When the addition amount of the low-melting-point glass powder is too high, the bonding and curing performance of the insulating coating adhesive is reduced, resulting in a reduction in the insulating coating effect and a reduction in the density of the magnetic core after molding and curing, which also leads to an increase in eddy current loss and hysteresis loss.

[0020] Furthermore, the ferrite powder in step (2) is manganese-zinc ferrite powder or nickel-zinc ferrite powder with a particle size of 1 to 10 μm.

[0021] Furthermore, the mass ratio of the insulating coating adhesive to the ferrite magnetic powder in step (2) is 1:10 to 100.

[0022] Furthermore, the pressure-maintaining sintering treatment in step (2) is carried out under air conditions, and the time of the pressure-maintaining sintering treatment is 15 to 60 minutes.

[0023] A low-loss inductor magnetic core is prepared by the above method.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention adopts addition-type curable silicone resin as the adhesive for ferrite magnetic powder, which has lower curing shrinkage and better toughness than conventional organic resin adhesives such as epoxy resin adhesives. At the same time, the porous SiO2 generated by the silicone resin adhesive during the later high-temperature sintering process can be used as a filling carrier for low-melting-point glass, which can significantly improve the insulation coating effect and the density of the magnetic core after molding and curing, thereby reducing losses.

[0026] (2) The present invention uses an addition-type curable silicone resin to bond ferrite magnetic powder. Compared with conventional silicone resins such as MQ silicone resin, it can be cured and molded at a lower pressure, with a low preparation cost; and no additional organic solvents and lubricants are required, and the resulting magnetic core has better magnetic properties.

[0027] (3) The present invention can further reduce the core loss by further adjusting the ratio of low-melting-point glass powder to silicone resin adhesive. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

[0029] Example 1

[0030] A method for preparing a low-loss inductor core comprises the following steps:

[0031] (1) Preparation of insulation coating adhesive:

[0032] In parts by weight, 70 parts of vinyl silicone oil with a viscosity of 200 mPa·s and a vinyl content of 6.5%, 30 parts of hydrogenated silicone oil with a viscosity of 150 mPa·s and a hydrogen content of 1.2%, 0.01 parts of divinyltetramethyldisiloxane platinum complex catalyst, 0.1 parts of 1-ethynyl-1-cyclohexanol inhibitor and 20 parts of low-melting-point glass powder with an average particle size of 4 μm and a melting point of 400°C are mixed uniformly at room temperature to obtain an insulating coating adhesive.

[0033] (2) Preparation of low-loss inductor core:

[0034] Five parts of the obtained insulating coating adhesive were evenly mixed with 100 parts of manganese-zinc ferrite magnetic powder with an average particle size of 4 μm. The mixture was first molded and cured for 10 minutes at a temperature of 80°C and a pressure of 400 MPa under nitrogen protection. The mixture was then heated to 600°C and sintered for 30 minutes under air conditions to obtain a low-loss inductor core.

[0035] Example 2

[0036] A method for preparing a low-loss inductor core comprises the following steps:

[0037] (1) Preparation of insulation coating adhesive:

[0038] In parts by weight, 80 parts of vinyl silicone oil with a viscosity of 1000 mPa·s and a vinyl content of 5.0%, 20 parts of hydrogen-containing silicone oil with a viscosity of 150 mPa·s and a hydrogen content of 1.2%, 0.01 parts of divinyltetramethyldisiloxane platinum complex catalyst, 0.1 parts of 1-ethynyl-1-cyclohexanol inhibitor and 20 parts of low-melting-point glass powder with an average particle size of 5 μm and a melting point of 350°C are mixed uniformly at room temperature to obtain an insulating coating adhesive.

[0039] (2) Preparation of low-loss inductor core:

[0040] 6 parts of the obtained insulating coating adhesive were evenly mixed with 100 parts of manganese-zinc ferrite magnetic powder with an average particle size of 5 μm. The mixture was first molded and cured for 10 minutes at a temperature of 80°C and a pressure of 500 MPa under nitrogen protection. Then the temperature was raised to 600°C and sintered for 30 minutes under air conditions to obtain a low-loss inductor core.

[0041] Example 3

[0042] A method for preparing a low-loss inductor core comprises the following steps:

[0043] (1) Preparation of insulation coating adhesive:

[0044] In parts by weight, 60 parts of vinyl silicone oil with a viscosity of 200 mPa·s and a vinyl content of 6.5%, 40 parts of hydrogenated silicone oil with a viscosity of 1000 mPa·s and a hydrogen content of 0.8%, 0.01 parts of divinyltetramethyldisiloxane platinum complex catalyst, 0.1 parts of 1-ethynyl-1-cyclohexanol inhibitor and 20 parts of low-melting-point glass powder with an average particle size of 3 μm and a melting point of 450°C are mixed uniformly at room temperature to obtain an insulating coating adhesive.

[0045] (2) Preparation of low-loss inductor core:

[0046] Four parts of the obtained insulating coating adhesive were evenly mixed with 100 parts of manganese-zinc ferrite magnetic powder with an average particle size of 3 μm. The mixture was first molded and cured for 10 minutes under nitrogen protection at 80°C and a pressure of 300 MPa. The mixture was then heated to 700°C and sintered for 30 minutes under air conditions to obtain a low-loss inductor core.

[0047] Example 4

[0048] A method for preparing a low-loss inductor core comprises the following steps:

[0049] (1) Preparation of insulation coating adhesive:

[0050] In parts by weight, 70 parts of vinyl silicone oil with a viscosity of 200 mPa·s and a vinyl content of 6.5%, 30 parts of hydrogenated silicone oil with a viscosity of 150 mPa·s and a hydrogen content of 1.2%, 0.01 parts of divinyltetramethyldisiloxane platinum complex catalyst, 0.1 parts of 1-ethynyl-1-cyclohexanol inhibitor and 20 parts of low-melting-point glass powder with an average particle size of 4 μm and a melting point of 400°C are mixed uniformly at room temperature to obtain an insulating coating adhesive.

[0051] (2) Preparation of low-loss inductor core:

[0052] Five parts of the obtained insulating coating adhesive were evenly mixed with 100 parts of nickel-zinc ferrite magnetic powder with an average particle size of 4 μm. The mixture was first molded and cured for 15 minutes at a temperature of 80°C and a pressure of 400 MPa under nitrogen protection. The temperature was then raised to 600°C and sintered for 45 minutes under air conditions to obtain a low-loss inductor core.

[0053] Example 5

[0054] A method for preparing a low-loss inductor core. Compared with Example 1, the amount of low-melting-point glass powder added is increased to 30 parts, and the rest are the same.

[0055] Example 6

[0056] A method for preparing a low-loss inductor core. Compared with Example 1, the amount of low-melting-point glass powder added is increased to 40 parts, and the rest are the same.

[0057] Example 7

[0058] A method for preparing a low-loss inductor core. Compared with Example 1, the amount of low-melting-point glass powder added is increased to 50 parts, and the rest are the same.

[0059] Example 8

[0060] A method for preparing a low-loss inductor core. Compared with Example 1, the amount of low-melting-point glass powder added is reduced to 10 parts, and the rest are the same.

[0061] Example 9

[0062] A method for preparing a low-loss inductor core. Compared with Example 1, the amount of low-melting-point glass powder added is reduced to 5 parts, and the rest are the same.

[0063] Comparative Example 1

[0064] A method for preparing a low-loss inductor core. Compared with Example 1, the amount of low-melting-point glass powder added is reduced to 0 parts, and the rest are the same.

[0065] Comparative Example 2

[0066] A method for preparing a low-loss inductor core comprises the following steps:

[0067] (1) Preparation of insulation coating adhesive:

[0068] By weight, 100 parts of bisphenol A epoxy resin adhesive and 20 parts of low-melting-point glass powder with an average particle size of 4 μm and a melting point of 400° C. are uniformly mixed at room temperature to obtain an insulating coating adhesive.

[0069] (2) The preparation of the low-loss inductor core is the same as that in Example 1.

[0070] Comparative Example 3

[0071] A method for preparing a low-loss inductor core comprises the following steps:

[0072] (1) Preparation of insulation coating adhesive:

[0073] By weight, 200 parts of MQ silicone resin toluene solution with a solid content of 50% and 20 parts of low-melting-point glass powder with an average particle size of 4 μm and a melting point of 400° C. are uniformly mixed at room temperature to obtain an insulating coating adhesive.

[0074] (2) The preparation of the low-loss inductor core is the same as that in Example 1.

[0075] The effective magnetic permeability (f=500kHz) and total loss (f=100kHz, Bm=50mT) of the inductor cores obtained in the above embodiments and comparative examples were tested, and the results are shown in Table 1 below.

[0076] Table 1

[0077] Test sample / performance Effective magnetic permeability <![CDATA[Total loss, mW / cm 3 > Example 1 76 256.2 Example 2 72 224.5 Example 3 85 278.9 Example 4 81 270.3 Example 5 82 275.6 Example 6 90 291.0 Example 7 122 430.2 Example 8 77 259.5 Example 9 75 286.4 Comparative Example 1 71 335.8 Comparative Example 2 78 365.7 Comparative Example 3 87 350.6

[0078] Comparisons of Example 1 with Examples 5-9 and Comparative Example 1 in Table 1 show that as the content of low-melting-point glass frit in the insulating coating adhesive increases, the magnetic permeability of the resulting magnetic core increases, while the total loss initially decreases and then increases. While Comparative Example 1, which lacks low-melting-point glass frit, achieves good insulating coating and reduces eddy current losses, the air gaps generated by high-temperature sintering cannot be effectively filled, reducing the core density and leading to a significant increase in hysteresis losses, ultimately increasing total losses. In Example 7, the excessive addition of low-melting-point glass reduces the bonding and curing properties of the insulating coating adhesive, resulting in reduced insulating coating effectiveness and lower core density after compression curing, ultimately leading to a significant increase in total losses. When the low-melting-point glass frit is added in an amount of 5% to 40% of the total mass of the vinyl silicone oil and hydrogenated silicone oil, good overall magnetic properties are achieved. Comparisons of Example 1 and Comparative Example 2 show that the combination of the present invention's organosilicon adhesive and low-melting-point glass frit significantly reduces core losses compared to conventional epoxy resins combined with low-melting-point glass frit. This is because the porous SiO2 formed during the high-temperature sintering process of the present invention's organosilicon adhesive can serve as a filler for low-melting-point glass, significantly improving the insulation coating effect and the density of the magnetic core after molding and curing, thereby reducing eddy current and hysteresis losses. A comparison of Example 1 and Comparative Example 3 shows that the present organosilicon adhesive can further improve the insulation coating effect and reduce eddy current losses compared to existing MQ silicone resin adhesives.

[0079] The above embodiments are preferred implementations of the present invention, but the implementations of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a low-loss inductor core, characterized in that: The method comprises the following preparation steps: (1) Preparation of insulation coating adhesive: Vinyl silicone oil, hydrogen-containing silicone oil, platinum complex catalyst, inhibitor and low-melting-point glass powder are uniformly mixed at room temperature to obtain an insulating coating adhesive; (2) Preparation of low-loss inductor core: The obtained insulating coating adhesive is evenly mixed with ferrite magnetic powder, firstly molded and cured at a temperature of 60-100°C and a pressure of 200-500 MPa, and then heated to 500-800°C and sintered to obtain a low-loss inductor core; The low-melting-point glass powder in step (1) has a particle size of 1 to 10 μm and a melting point of 300 to 600° C. The amount of the low-melting-point glass powder added is 5% to 40% of the total mass of the vinyl silicone oil and the hydrogenated silicone oil. The sintering treatment in step (2) is carried out under air conditions, and the sintering treatment time is 15 to 60 minutes.

2. The method for preparing a low-loss inductor core according to claim 1, wherein: The vinyl silicone oil in step (1) is a vinyl silicone oil with a viscosity of 100-2000 mPa·s and a vinyl content of 1%-10%; the hydrogen-containing silicone oil is a hydrogen-containing silicone oil with a viscosity of 100-2000 mPa·s and a hydrogen content of 0.2%-1.5%.

3. The method for preparing a low-loss inductor core according to claim 2, wherein: The mass ratio of the vinyl silicone oil to the hydrogenated silicone oil is 1:0.1-0.

6.

4. The method for preparing a low-loss inductor core according to claim 1, wherein: The amount of the platinum complex catalyst added in step (1) is 0.005% to 0.02% of the total mass of the vinyl silicone oil and the hydrogen-containing silicone oil; the inhibitor adopts an acetylene alcohol inhibitor, and the amount of the acetylene alcohol inhibitor added is 0.05% to 0.2% of the total mass of the vinyl silicone oil and the hydrogen-containing silicone oil.

5. The method for preparing a low-loss inductor core according to claim 1, wherein: The ferrite powder in step (2) is manganese-zinc ferrite powder or nickel-zinc ferrite powder with a particle size of 1 to 10 μm.

6. The method for preparing a low-loss inductor core according to claim 1, wherein: The mass ratio of the insulating coating adhesive to the ferrite magnetic powder in step (2) is 1:10~100.

7. A low-loss inductor core, characterized in that: It is prepared by the method according to any one of claims 1 to 6.