A process for preparing the internal structure of a multilayer power inductor with controllable magnetic permeability gradient and its product

Abstract

The present application relates to the field of inductor technology, and more specifically, to a process for preparing the internal structure of a laminated power inductor with controllable magnetic permeability gradient and its product, comprising the following preparation steps: S1, using a lamination process to prepare a plurality of FeSiCr prepregs using FeSiCr slurry, wherein the prepregs used for the first layer and the top layer are not punched, and the remaining prepregs are punched; S2, printing NiZnCuFeO3 slurry on the FeSiCr prepreg to form a NiZnCuFeO3 circuit layer, and the circuit layer must pass through the holes; S3, The inner electrode lines are printed on the surface of the ZnCuFeO3 circuit layer. The edge of the inner electrode ring cannot exceed the edge of the NiZnCuFeO3 circuit layer. The inner electrode ring of the first layer of prepreg does not need to pass through the holes, while the inner electrode lines of the remaining prepregs must pass through the holes. S4. After the inner electrode lines are printed on the first layer of prepreg, the second layer of prepreg is placed, and steps S2-S3 are repeated. Then the third layer of prepreg is placed, and steps S2-S3 are repeated again, and so on. Finally, the top layer of prepreg is placed to form a multi-layer structure to obtain the internal structure of the inductor.

Description

Technical Field

[0001] The present application relates to the field of inductor technology, and more specifically, to a process for preparing the internal structure of a laminated power inductor with controllable magnetic permeability gradient and its product. Background Art

[0002] Inductors are primarily used in chips as key components of power supply modules, powering the front-ends of chips such as GPUs, CPUs, ASICs, and FPGAs. Inductors store and release energy through the principle of electromagnetic induction, thereby smoothing current, reducing noise, and stabilizing power supply within the circuit. When the chip is in low-load or sleep mode, the actual current flowing through the inductor is low. In this state, the inductor's losses are primarily due to magnetic losses. Specifically, at low currents, inductor losses are primarily caused by magnetic core losses, primarily including hysteresis losses and eddy current losses. These losses affect the inductor's efficiency and performance. Summary of the Invention

[0003] In order to reduce the magnetic loss of the inductor when the chip is in a low-load or dormant state, the present application proposes a process for preparing the internal structure of a laminated power inductor with controllable magnetic permeability gradient and its product.

[0004] In a first aspect, the present application provides a process for preparing the internal structure of a laminated power inductor with controllable magnetic permeability gradient, using the following technical solutions:

[0005] A process for preparing the internal structure of a laminated power inductor with controllable magnetic permeability gradient includes the following steps:

[0006] S1. Using a lamination process, FeSiCr slurry is used to prepare a plurality of FeSiCr prepregs, wherein the prepregs used for the first and top layers are not perforated, and the remaining prepregs are perforated;

[0007] S2. Printing NiZnCuFeO3 slurry on the FeSiCr prepreg to form a NiZnCuFeO3 circuit layer, and the circuit layer must pass through the holes; wherein, the first layer prepreg does not need to pass through the holes, and the top layer prepreg does not need to be printed with NiZnCuFeO3 slurry;

[0008] S3. Print the inner electrode lines on the surface of the NiZnCuFeO3 circuit layer. The edge of the inner electrode ring cannot exceed the edge of the NiZnCuFeO3 circuit layer. The inner electrode ring of the first layer of prepreg does not need to pass through the hole, while the inner electrode lines of the other prepregs must pass through the hole.

[0009] S4. After the inner electrode lines are printed on the first layer of prepreg, place the second layer of prepreg and repeat steps S2-S3. Then place the third layer of prepreg and repeat steps S2-S3, and so on, until the required number of layers is reached. Finally, place the top layer of prepreg to form a multi-layer structure and obtain the internal structure of the inductor.

[0010] By adopting the above technical solution and adjusting the system coordination of the FeSiCr prepreg and the NiZnCuFeO3 layer, gradient control is achieved. When the chip is under low load or in sleep mode, the magnetic lines of force inside the inductor are mainly concentrated in the NiZnCuFeO3 layer, and the inductor exhibits high inductance. As the load of the chip increases, the NiZnCuFeO3 layer gradually becomes magnetically saturated, and the corresponding magnetic lines of force are concentrated in the FeSiCr layer. At this time, the inductor exhibits low inductance, achieving an overall higher power conversion efficiency in the full power range of DC-DC conversion and reducing losses.

[0011] At the same time, in this application, by printing NiZnCuFeO3 slurry on the FeSiCr semi-cured sheet and printing the inner electrode line, a multi-layer structure inductor is formed, which can enhance the electromagnetic induction effect and improve the energy storage and release efficiency, thereby playing a better role in smoothing current, reducing noise and stabilizing power supply in the circuit.

[0012] Preferably, the thickness of the FeSiCr prepreg and the NiZnCuFeO3 layer is 1:(0.2-0.5).

[0013] By adopting the above technical solution, the thickness of the FeSiCr prepreg and NiZnCuFeO3 layer is easily achieved, thus reducing the loss of the inductor. This ensures the structural stability and reliability of the inductor, enabling it to withstand long-term high-power and high-frequency operation, reducing the failure rate of the inductor during use, and extending the service life of the inductor.

[0014] Preferably, the FeSiCr slurry is prepared by the following method:

[0015] 1) ball milling the FeSiCr powder to 200-300 nm to obtain a first mixed metal powder;

[0016] 2) Grinding the first mixed metal powder, the first solvent, the binder, the coupling agent, the plasticizer, and polymethyl methacrylate to a viscosity of 1200-2000 cps to obtain a FeSiCr slurry, wherein the binder is composed of ethyl cellulose, polyvinyl butyral resin, and polyvinyl alcohol.

[0017] Preferably, the weight parts of the raw materials used to prepare the FeSiCr slurry are as follows:

[0018] 110-140 parts of FeSiCr powder

[0019] 100-150 parts of the first solvent

[0020] 10-20 parts of adhesive

[0021] 3-5 parts coupling agent

[0022] Plasticizer 0.8-1 part

[0023] 40-50 parts of polymethyl methacrylate.

[0024] The FeSiCr prepreg prepared by adopting the above technical solution can reduce the magnetic loss of the inductor under low load or dormant state, reduce eddy current loss and hysteresis loss, thereby improving the efficiency and performance of the inductor.

[0025] Mixing iron, silicon, and chromium powders and then ball-milling them helps to better disperse the metal powders in the solvent and adhesive, improving the uniformity and stability of the slurry, making the internal structure of the subsequently prepared inductor more dense and uniform. At the same time, due to the fine and evenly distributed metal powder particles in the slurry and the good adhesion of the adhesive, the internal structure of the prepared inductor has low losses. Especially under low load or dormant conditions, the loss of the inductor is mainly caused by the magnetic loss of the magnetic core. Inductors prepared with this slurry can effectively reduce hysteresis loss and eddy current loss, thereby improving the efficiency of the inductor.

[0026] The first mixed metal powder is ground with the first solvent, binder, coupling agent, plasticizer, and polymethyl methacrylate until the viscosity reaches 1200-2000 cps. This ensures that the FeSiCr slurry has good printability and formability, allowing it to be easily coated on a substrate through a printing process and subsequently cured to form a stable inductor internal structure. This also facilitates the subsequent printing and coating of the NiZnCuFeO3 slurry.

[0027] In the present application, the binder is prepared by ethyl cellulose, polyvinyl butyral resin and polyvinyl alcohol, so that the good compatibility between the components of the FeSiCr slurry and the strong bonding effect of the binder make it less likely for the inductor to experience performance degradation or failure during long-term use.

[0028] Preferably, the weight ratio of the ethyl cellulose, the polyvinyl butyral resin and the polyvinyl alcohol is 5:(1-3):(4-6).

[0029] By adopting the above technical solution and optimizing the dosage of ethyl cellulose, polyvinyl butyral resin, and polyvinyl alcohol, it is possible to precisely control the viscosity of the slurry. As the main adhesive component, ethyl cellulose's high viscosity provides a stable skeleton for the slurry. The addition of polyvinyl butyral resin and polyvinyl alcohol can adjust the viscosity of the slurry, making it more suitable for coating and printing processes. At the same time, polyvinyl alcohol has good solubility, which can help metal powder and other ingredients better disperse in the solvent to form a uniform slurry. This helps to evenly distribute the metal powder during the subsequent preparation of the inductor's internal structure, thereby improving the performance of the inductor.

[0030] Preferably, the NiZnCuFeO3 slurry is prepared by the following method:

[0031] A. Mix nickel oxide powder, zinc oxide powder, copper oxide powder and ferric oxide powder, ball mill them to 200-500 nm, and sinter them to obtain a second mixed metal powder;

[0032] B. Mix polymethyl methacrylate, a second solvent, epoxy resin, ethyl cellulose and a curing agent, then add the second mixed metal powder and a dispersant, grind and stir to obtain a NiZnCuFeO3 slurry grinded to a viscosity of 2000-4000 cps.

[0033] Preferably, the weight parts of the raw materials used to prepare the NiZnCuFeO3 slurry are as follows:

[0034] 25-30 parts nickel oxide powder

[0035] 20-30 parts zinc oxide powder

[0036] 15-20 parts copper oxide powder

[0037] 20-30 parts of iron oxide powder

[0038] 5-10 parts of polymethyl methacrylate

[0039] 100-150 parts of the second solvent

[0040] 10-15 parts epoxy resin

[0041] 6-10 parts of ethyl cellulose 1-3 parts of curing agent

[0042] 3-5 parts of dispersant.

[0043] Preferably, the firing process is as follows: heating from room temperature to 200-300°C over 1-2 hours, then heating to 500-600°C over 2-3 hours, keeping warm for 1-2 hours, then heating to 800-900°C over 1-2 hours, then heating to 1100-1200°C over 1-2 hours, and keeping warm for 2.5-4 hours.

[0044] By adopting the above technical solution, the prepared NiZnCuFeO3 slurry has low magnetic loss characteristics. The slurry prepared by the method is printed on the internal structure of the inductor and used in combination with the FeSiCr prepreg to achieve the required magnetic permeability gradient and chemical stability, which can further reduce the magnetic loss of the inductor under low load or dormant state.

[0045] By mixing nickel oxide powder, zinc oxide powder, copper oxide powder and ferric oxide powder and then ball milling, the powder can be ground to 200-500nm, which helps to obtain better dispersion and uniformity in the subsequent preparation of the slurry, thereby improving the overall performance of the slurry. By adding ingredients such as polymethyl methacrylate, a second solvent, epoxy resin, ethyl cellulose and a curing agent, and after grinding and stirring, a NiZnCuFeO3 slurry with a viscosity of 2000-4000cps is obtained, so that the NiZnCuFeO3 slurry has good fluidity and is easy to print and coat during the inductor preparation process. The addition of a dispersant during the preparation process helps to evenly disperse the second mixed metal powder in the slurry so that the metal powder can be evenly distributed in the internal structure of the inductor, thereby improving the electromagnetic performance and stability of the inductor.

[0046] Preferably, the epoxy resin has a viscosity of 2000-10000 mPa.s (25° C.) and an epoxy value of 3-20 eq / 100 g.

[0047] By adopting the above technical solution, using a moderate viscosity and epoxy value makes the epoxy resin easier to control and operate during the preparation and curing process. During the curing process, it can be better mixed with components such as metal powder to form a dense structure, which helps to improve the mechanical strength and reliability of the inductor.

[0048] Preferably, the relative magnetic permeability of the FeSiCr prepreg is 20-60, and the saturation magnetic flux of the FeSiCr prepreg is 0.8-1.5T.

[0049] Preferably, the relative magnetic permeability of the NiZnCuFeO3 slurry layer is 40-200, and the saturation magnetic flux of the NiZnCuFeO3 slurry layer is 0.01-0.5T.

[0050] By adopting the above technical solution, the relative magnetic permeability and saturation magnetic flux density of the FeSiCr prepreg and the NiZnCuFeO3 slurry layer are optimized, so that the inductor has lower magnetic loss at high frequency while maintaining high efficiency at high current, thereby improving the energy efficiency ratio of the inductor.

[0051] In a second aspect, the present application provides an inductor internal structure manufactured by a process for manufacturing an internal structure of a laminated power inductor with controllable magnetic permeability gradient, which adopts the following technical solution:

[0052] An inductor internal structure manufactured by a process for preparing the internal structure of a laminated power inductor with controllable magnetic permeability gradient includes a FeSiCr prepreg, a NiZnCuFeO3 slurry layer, and an inner electrode wire. The NiZnCuFeO3 slurry layer is formed on the upper surface of the FeSiCr prepreg by printing. The structural dimensions and thickness of the NiZnCuFeO3 slurry layer are adjustable to achieve controllable inductance gradient. The inner electrode wire is formed on the upper surface of the NiZnCuFeO3 slurry layer by printing. The FeSiCr prepreg, the NiZnCuFeO3 slurry layer, and the inner electrode wire are stacked several times in sequence.

[0053] By adopting the above technical solution, a multi-layer structure is formed. This structural design not only improves the structural stability and reliability of the inductor, but also can withstand long-term high-power and high-frequency operation, reduces the failure rate of the inductor during use, and extends the service life of the inductor.

[0054] In summary, this application has the following beneficial effects:

[0055] 1. Gradient control is achieved by adjusting the system coordination of the FeSiCr prepreg and the NiZnCuFeO3 layer. When the chip is under low load or in sleep mode, the magnetic lines of force inside the inductor are mainly concentrated in the NiZnCuFeO3 layer, and the inductor exhibits high inductance. As the chip load increases, the NiZnCuFeO3 layer gradually becomes magnetically saturated, and the corresponding magnetic lines of force are concentrated in the FeSiCr layer. At this time, the inductor exhibits low inductance, achieving an overall higher power conversion efficiency in the full power range of DC-DC conversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is a schematic diagram of the single stacking forming process of the magnetic permeability gradient controllable laminated power inductor in this application.

[0057] Explanation of the accompanying symbols: 1. FeSiCr prepreg; 2. NiZnCuFeO3 slurry layer; 3. Inner electrode line. DETAILED DESCRIPTION

[0058] Preparation Example

[0059] Polymethyl methacrylate was purchased from Dongguan Hongkuo Plastic Co., Ltd., model number 8137, and the origin was Dow, Thailand.

[0060] Titanate coupling agent was purchased from Shandong Hui'an Chemical Co., Ltd. with CAS number 61417-49-0.

[0061] The aluminate coupling agent was purchased from Shandong Guohua Chemical Co., Ltd. and the implementation standard was the national standard.

[0062] Polyvinyl butyral resin was purchased from Hubei Yamade Biopharmaceutical Co., Ltd., model number is Butvar-76.

[0063] FeSiCr powder was purchased from Qinghe County Tebo Metal Materials Co., Ltd., model number 7485210.

[0064] Preparation Example 1

[0065] A FeSiCr slurry is prepared by the following method:

[0066] 1. Ball mill 110 g of FeSiCr powder to 200-240 nm to obtain a first mixed metal powder;

[0067] 2) Grinding the first mixed metal powder, 100 g of the first solvent (ethyl acetate), 10 g of the binder, 3 g of the coupling agent (KH550), 0.8 g of the plasticizer (diisononyl phthalate), and 40 g of polymethyl methacrylate to a viscosity of 1200 cps to obtain a FeSiCr slurry, wherein the binder is composed of ethyl cellulose, polyvinyl butyral resin, and polyvinyl alcohol in a weight ratio of 5:1:4.

[0068] The molecular weight of polyvinyl alcohol is 2000.

[0069] The difference between Preparation Example 2-3 and Preparation Example 1 is that the raw material types, amounts and experimental parameters for preparing the FeSiCr slurry are different. The specific differences are shown in Table 1:

[0070] Table 1 Preparation Examples 1-3, raw material types, amounts and experimental parameters for preparing FeSiCr slurries

[0071]

[0072] Preparation Example 4

[0073] A NiZnCuFeO3 slurry is prepared by the following method:

[0074] 1. Mix 25g of nickel oxide powder, 20g of zinc oxide powder, 15g of copper oxide powder, and 20g of ferric oxide powder, ball mill them to 200-300nm, and sinter them to obtain a second mixed metal powder;

[0075] The firing process is as follows: raise the temperature from room temperature to 200°C over 1 hour, then raise the temperature to 500°C over 2 hours, keep warm for 1 hour, then raise the temperature to 800°C over 1 hour, then raise the temperature to 1100°C over 1 hour, and keep warm for 2.5 hours.

[0076] B. Mix 5 g of polymethyl methacrylate, 100 g of the second solvent (ethyl acetate), 10 g of epoxy resin, 6 g of ethyl cellulose, and 1 g of a curing agent (ethylenediamine), then add the second mixed metal powder and 3 g of a dispersant (talc), grind and stir to obtain a NiZnCuFeO3 slurry ground to a viscosity of 2000 cps.

[0077] The epoxy resins used in the preparation examples are all bisphenol A epoxy resins. The viscosity of the epoxy resin in Preparation Example 1 is 200 mPa.s (25° C.) and the epoxy value is 3 eq / 100 g.

[0078] The difference between Preparation Example 5-6 and Preparation Example 4 is that the raw material types, amounts and experimental parameters for preparing NiZnCuFeO3 slurry are different. The specific differences are shown in Table 2:

[0079] Table 2 Raw material types, amounts and experimental parameters for preparing NiZnCuFeO3 slurries in Preparation Examples 4-6

[0080]

[0081] The firing process in Preparation Example 5 is as follows: raise the temperature from room temperature to 250°C over 1.5 hours, then raise the temperature to 550°C over 2.5 hours, keep warm for 1.5 hours, then raise the temperature to 850°C over 1.5 hours, then raise the temperature to 1150°C over 1.5 hours, and keep warm for 3.4 hours.

[0082] The firing process in Preparation Example 6 is as follows: raise the temperature from room temperature to 300°C over 2 hours, then raise the temperature to 600°C over 3 hours, keep warm for 2 hours, then raise the temperature to 900°C over 2 hours, then raise the temperature to 1200°C over 2 hours, and keep warm for 4 hours.

[0083] Preparation Comparative Example

[0084] Preparation Comparative Example 1

[0085] A FeSiCr slurry. The difference between this comparative preparation example and Preparation Example 1 is that the binder is ethyl cellulose.

[0086] Preparation Comparative Example 2

[0087] A FeSiCr slurry. The difference between this comparative preparation example and Preparation Example 1 is that the binder is composed of polyvinyl butyral resin and polyvinyl alcohol in a weight ratio of 1:4.

[0088] Preparation Comparative Example 3

[0089] A FeSiCr slurry. The difference between this comparative preparation example and Preparation Example 1 is that polyvinyl alcohol is used instead of polymethyl methacrylate.

[0090] The molecular weight of polyvinyl alcohol is 2000.

[0091] Preparation Comparative Example 4

[0092] A MoZnCuFeO3 slurry. The difference between this comparative preparation example and Preparation Example 1 is that molybdenum powder is used instead of nickel oxide powder.

[0093] Preparation Comparative Example 5

[0094] A NiFeCuFeO3 slurry. The difference between this comparative preparation example and Preparation Example 1 is that iron powder is used instead of zinc oxide powder.

[0095] Preparation Comparative Example 6

[0096] A NiZnCuFeO3 slurry. The difference between this comparative preparation example and Preparation Example 1 is that iron powder is used instead of copper oxide powder.

[0097] Preparation Comparative Example 7

[0098] A NiZnCuFeO3 slurry. The difference between this comparative preparation example and Preparation Example 1 is that polyvinyl alcohol is used instead of polymethyl methacrylate.

[0099] The molecular weight of polyvinyl alcohol is 2000.

[0100] Example

[0101] Example 1

[0102] An internal structure of a multilayer power inductor with controllable magnetic permeability gradient, such as Figure 1 As shown, the magnetic permeability gradient controllable laminated power inductor includes a FeSiCr prepreg 1, a NiZnCuFeO3 slurry layer 2 and an inner electrode wire 3. The NiZnCuFeO3 slurry layer 2 is formed on the upper surface of the FeSiCr prepreg 1 by printing, and the inner electrode wire 3 is formed on the upper surface of the NiZnCuFeO3 slurry layer 2 by printing. The FeSiCr prepreg 1, the NiZnCuFeO3 slurry layer 2 and the inner electrode wire 3 are stacked in sequence several times.

[0103] The internal structure of the controllable magnetic permeability gradient laminated power inductor is prepared by the following method:

[0104] S1. Using a lamination process, a plurality of FeSiCr prepregs were prepared using the FeSiCr slurry (Preparation Example 1), wherein the prepregs used for the first and top layers were not perforated, and the remaining prepregs were perforated;

[0105] S2. Printing NiZnCuFeO3 slurry (Preparation Example 4) on the FeSiCr prepreg to form a NiZnCuFeO3 circuit layer, and the circuit layer must pass through the holes; wherein, the first layer prepreg does not need to pass through the holes, and the top layer prepreg does not need to be printed with NiZnCuFeO3 slurry;

[0106] S3. Print the inner electrode lines (silver paste) on the surface of the NiZnCuFeO3 circuit layer. The edge of the inner electrode ring cannot exceed the edge of the NiZnCuFeO3 circuit layer. The inner electrode ring of the first layer of prepreg does not need to pass through the hole, while the inner electrode lines of the other prepregs must pass through the hole.

[0107] S4. After the inner electrode lines are printed on the first layer of prepreg, place the second layer of prepreg and repeat steps S2-S3. Then place the third layer of prepreg and repeat steps S2-S3, and so on, until the required number of layers is reached. Finally, place the top layer of prepreg to form a multi-layer structure and obtain the internal structure of the inductor.

[0108] The relative magnetic permeability of the FeSiCr prepreg is 20, and the saturation magnetic flux of the FeSiCr prepreg is 0.8T.

[0109] The relative magnetic permeability of the NiZnCuFeO3 slurry layer is 40, and the saturation magnetic flux of the NiZnCuFeO3 slurry layer is 0.01T.

[0110] Example 2

[0111] An internal structure of a laminated power inductor with controllable magnetic permeability gradient. The difference between this embodiment and Example 1 is that the FeSiCr slurry comes from Preparation Example 2, and the NiZnCuFeO3 slurry comes from Preparation Example 5.

[0112] The relative magnetic permeability of the FeSiCr prepreg is 40, and the saturation magnetic flux of the FeSiCr prepreg is 1.2T.

[0113] The relative magnetic permeability of the NiZnCuFeO3 slurry layer is 100, and the saturation magnetic flux of the NiZnCuFeO3 slurry layer is 0.3T.

[0114] Example 3

[0115] An internal structure of a laminated power inductor with controllable magnetic permeability gradient. The difference between this embodiment and Example 1 is that the FeSiCr slurry comes from Preparation Example 3, and the NiZnCuFeO3 slurry comes from Preparation Example 6.

[0116] The relative magnetic permeability of the FeSiCr prepreg is 60, and the saturation magnetic flux of the FeSiCr prepreg is 1.5T.

[0117] The relative magnetic permeability of the NiZnCuFeO3 slurry layer is 200, and the saturation magnetic flux of the NiZnCuFeO3 slurry layer is 0.5T.

[0118] Example 4

[0119] An internal structure of a laminated power inductor with controllable magnetic permeability gradient. The difference between this embodiment and Example 1 is that the FeSiCr slurry is prepared from Comparative Example 1.

[0120] Example 5

[0121] An internal structure of a laminated power inductor with controllable magnetic permeability gradient. The difference between this embodiment and Example 1 is that the FeSiCr slurry comes from the preparation of Comparative Example 2.

[0122] Example 6

[0123] An internal structure of a laminated power inductor with controllable magnetic permeability gradient. The difference between this embodiment and Example 1 is that the FeSiCr slurry comes from the preparation of Comparative Example 3.

[0124] Example 7

[0125] An internal structure of a laminated power inductor with controllable magnetic permeability gradient. The difference between this embodiment and Example 1 is that the FeSiCr slurry comes from the preparation of Comparative Example 4.

[0126] Example 8

[0127] An internal structure of a laminated power inductor with controllable magnetic permeability gradient. The difference between this embodiment and Example 1 is that the FeSiCr slurry comes from the preparation of Comparative Example 5.

[0128] Example 9

[0129] An internal structure of a laminated power inductor with controllable magnetic permeability gradient. The difference between this embodiment and Example 1 is that the FeSiCr slurry is prepared from Comparative Example 6.

[0130] Example 10

[0131] An internal structure of a laminated power inductor with controllable magnetic permeability gradient. The difference between this embodiment and Example 1 is that the FeSiCr slurry is prepared from Comparative Example 7.

[0132] Comparative Example

[0133] Comparative Example 1

[0134] An internal structure of a laminated power inductor with controllable magnetic permeability gradient. The difference between this comparative example and Example 1 is that step S2 is omitted, and the inner electrode line (silver paste) is directly printed on the FeSiCr prepreg.

[0135] Detection method / test method Magnetic loss: Use BH tester SY-8212 to test magnetic loss. A larger magnetic loss value means that more energy is converted into heat or other forms of energy and lost during the magnetization process, which will lead to reduced efficiency of the circuit or equipment.

[0136] Magnetic permeability testing: An Agilent 4991B instrument was used to test magnetic permeability at 1kHz, using a 16454A fixture. A higher magnetic permeability indicates a material is more easily magnetized. Under the same magnetic field strength, materials with higher magnetic permeability produce stronger magnetic induction intensity.

[0137] Shedding test: The internal structures of the inductors prepared in Examples 1-12 and Comparative Example 1 were placed in an environment at a temperature of 120°C and subjected to vibratory vibration every hour. After 72 hours, the inductors were removed and observed to see if the internal structures of the inductors bulged or shed. The experimental data are shown in Table 2:

[0138] Table 2 Experimental data of Examples 1-12 and Comparative Example 1

[0139]

[0140]

[0141] Comparing Example 1 with Comparative Example 1, the magnetic loss value in Example 1 is lower than that in Comparative Example 1; the magnetic permeability in Comparative Example 1 is lower than that in Example 1; in the shedding test, delamination occurs in Comparative Example 1, indicating that the internal structure of the inductor prepared by the preparation process in this application has low magnetic loss, suitable magnetic flux, and stable structural strength.

[0142] Comparing Example 1 with Examples 4-5, the magnetic loss value of Example 4-5 is slightly higher than that of Example 1; the magnetic permeability of Examples 4-5 is slightly lower than that of Example 1. In the shedding experiment, bubbles appeared in Example 4, and shedding occurred in Example 5. This shows that in this application, by preparing a binder with ethyl cellulose, polyvinyl butyral resin and polyvinyl alcohol, and then using it to prepare FeSiCr slurry, the magnetic flux and structural stability of the internal structure of the inductor can be improved, and the magnetic loss can also be reduced.

[0143] Comparing Example 1 with Example 6, the magnetic loss value of Example 6 is slightly higher than that of Example 1; the magnetic permeability in Example 6 is slightly lower than that in Example 1, and bubbles appear in Example 6 during the shedding test, indicating that in this application, by incorporating polymethyl methacrylate into the preparation of FeSiCr slurry, the magnetic flux and structural stability of the internal structure of the inductor can be improved, while the magnetic loss can also be reduced.

[0144] Comparing Example 1 with Examples 7-9, the magnetic loss value of Example 7-9 is higher than that of Example 1; the magnetic permeability in Example 7-9 is slightly lower than that of Example 1, indicating that the present application can increase the magnetic flux of the internal structure of the inductor while reducing the magnetic loss by combining nickel oxide powder, zinc oxide powder and copper oxide powder to prepare NiZnCuFeO3 slurry.

[0145] Comparing Example 1 with Example 10, the magnetic loss value of Example 10 is slightly higher than that of Example 1; the magnetic permeability in Example 10 is slightly lower than that in Example 1, and bubbles appear in Example 10 during the shedding test, indicating that in this application, by incorporating polymethyl methacrylate into the preparation of FeSiCr slurry, the magnetic flux and structural stability of the internal structure of the inductor can be improved, while the magnetic loss can also be reduced.

[0146] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A process for preparing the internal structure of a laminated power inductor with controllable magnetic permeability gradient, characterized in that: The method comprises the following preparation steps: S1. Using a lamination process, FeSiCr slurry is used to prepare a plurality of FeSiCr prepregs, wherein the prepregs used for the first and top layers are not perforated, and the remaining prepregs are perforated; S2. Printing NiZnCuFeO3 slurry on the FeSiCr prepreg to form a NiZnCuFeO3 circuit layer, and the circuit layer must pass through the holes; wherein, the first layer prepreg does not need to pass through the holes, and the top layer prepreg does not need to be printed with NiZnCuFeO3 slurry; S3. Print the inner electrode lines on the surface of the NiZnCuFeO3 circuit layer. The edge of the inner electrode ring cannot exceed the edge of the NiZnCuFeO3 circuit layer. The inner electrode ring of the first layer of prepreg does not need to pass through the hole, while the inner electrode lines of the other prepregs must pass through the hole. S4. After the inner electrode lines are printed on the first layer of prepreg, place the second layer of prepreg, repeat steps S2-S3, place the third layer of prepreg, repeat steps S2-S3, and so on, until the required number of layers is reached. Finally, place the top layer of prepreg to form a multi-layer structure to obtain the internal structure of the inductor; The FeSiCr slurry is prepared by the following method: 1) ball milling the FeSiCr powder to 200-300 nm to obtain a first mixed metal powder; 2) grinding the first mixed metal powder, the first solvent, the binder, the coupling agent, the plasticizer, and polymethyl methacrylate to a viscosity of 1200-2000 cps to obtain a FeSiCr slurry, wherein the binder is composed of ethyl cellulose, polyvinyl butyral resin, and polyvinyl alcohol; The weight ratio of the ethyl cellulose, the polyvinyl butyral resin and the polyvinyl alcohol is 5:(1-3):(4-6); The weight parts of the raw materials used to prepare the FeSiCr slurry are as follows: 110-140 parts of FeSiCr powder, 100-150 parts of a first solvent, 10-20 parts of an adhesive, 3-5 parts of a coupling agent, 0.8-1 parts of a plasticizer, and 40-50 parts of polymethyl methacrylate; The NiZnCuFeO3 slurry is prepared by the following method: A. Mix nickel oxide powder, zinc oxide powder, copper oxide powder and ferric oxide powder, ball mill them to 200-500 nm, and sinter them to obtain a second mixed metal powder; B. Mixing polymethyl methacrylate, a second solvent, an epoxy resin, ethyl cellulose, and a curing agent, adding a second mixed metal powder and a dispersant, grinding and stirring to obtain a NiZnCuFeO3 slurry ground to a viscosity of 2000-4000 cps; The weight parts of the raw materials used to prepare the NiZnCuFeO3 slurry are as follows: 25-30 parts of nickel oxide powder, 20-30 parts of zinc oxide powder, 15-20 parts of copper oxide powder, 20-30 parts of ferric oxide powder, 5-10 parts of polymethyl methacrylate, 100-150 parts of a second solvent, 10-15 parts of an epoxy resin, 6-10 parts of ethyl cellulose, 1-3 parts of a curing agent, and 3-5 parts of a dispersant; The epoxy resin has a viscosity of 2000-10000 mPa.s at 25° C. and an epoxy value of 3-20 eq / 100 g.

2. The process for preparing the internal structure of a laminated power inductor with controllable magnetic permeability gradient according to claim 1, characterized in that: The relative magnetic permeability of the FeSiCr prepreg is 20-60, and the saturation magnetic flux of the FeSiCr prepreg is 0.8-1.5T.

3. An inductor internal structure according to any one of claims 1 to 2, wherein the process for preparing the internal structure of a laminated power inductor with controllable magnetic permeability gradient is characterized in that: The invention comprises a FeSiCr prepreg (1), a NiZnCuFeO3 slurry layer (2) and an inner electrode line (3), wherein the NiZnCuFeO3 slurry layer (2) is formed on the upper surface of the FeSiCr prepreg (1) by printing, the structural size and thickness of the NiZnCuFeO3 slurry layer (2) are adjustable to achieve controllable inductance gradient, the inner electrode line (3) is formed on the upper surface of the NiZnCuFeO3 slurry layer (2) by printing, and the FeSiCr prepreg (1), the NiZnCuFeO3 slurry layer (2) and the inner electrode line (3) are stacked in sequence several times.

Images