Fabrication method of molded inductor and molded inductor

Abstract

This disclosure provides a method for preparing a molded inductor and the molded inductor itself. The method includes: mixing a thermosetting binder, a solvent, and magnetic material powder to prepare a magnetic composite material; baking the magnetic composite material to remove the solvent, then placing it in a hot-press mold for preheating and hot-pressing; wherein, before hot-pressing the magnetic composite material, a portion of the binder is cured. Experimental tests have shown that curing a portion of the binder before hot-pressing the magnetic composite material effectively improves the insulation resistance value of the final molded inductor.

Description

Technical Field

[0001] This invention relates to the field of inductor technology, and in particular to a method for preparing a molded inductor and the molded inductor itself. Background Technology

[0002] Molded inductors have been widely used due to their advantages such as convenient fabrication, miniaturization, strong electromagnetic interference resistance, low noise, and high frequency operation. Molded inductors are mainly composed of magnetic materials and binders. The magnetic materials contribute to the electromagnetic properties of the inductor, while the binder provides the bonding force between the magnetic materials and blocks the transmission of eddy currents between them to reduce losses.

[0003] In the manufacturing process, binders and magnetic material powders are typically mixed to form a magnetic composite material, which is then pressed into shape. The manufacturing process of integrally molded inductors can be divided into two main types based on the molding temperature: room temperature pressing (cold pressing) and high temperature pressing (hot pressing). Compared to cold pressing, hot pressing requires less molding pressure to achieve the same pressing density, and at the same molding pressure, achieves a higher pressing density. Therefore, integrally molded inductors prepared by hot pressing have higher reliability. However, a significant drawback of hot pressing is that, using the same materials and processes, the insulation resistance of integrally molded inductors prepared by hot pressing is significantly lower than that prepared by cold pressing. Therefore, improving the insulation resistance of integrally molded inductors has become a technical challenge. Summary of the Invention

[0004] Therefore, in order to improve the insulation resistance of a molded inductor, it is necessary to provide a method for fabricating a molded inductor.

[0005] According to one embodiment of this disclosure, a method for fabricating a molded inductor includes the following steps:

[0006] Magnetic composite materials are prepared by mixing thermosetting adhesives, solvents, and magnetic material powders.

[0007] The magnetic composite material is baked to remove the solvent, and then placed in a hot press mold for preheating and hot pressing.

[0008] Before hot-pressing the magnetic composite material, a portion of the adhesive is cured.

[0009] In one embodiment, curing a portion of the adhesive involves controlling the baking temperature of the baking process to be between 65°C and 120°C.

[0010] In one embodiment, curing a portion of the adhesive involves controlling the baking temperature of the baking process to be between 65°C and 90°C.

[0011] In one embodiment, the baking time of the baking process is controlled to be 60 min to 180 min.

[0012] In one embodiment, the baking time of the baking process is controlled to be 60 min to 150 min.

[0013] In one embodiment, curing a portion of the adhesive involves controlling the preheating time of the preheating process to be 20s to 150s.

[0014] In one embodiment, curing a portion of the adhesive involves controlling the preheating time of the preheating process to be 20s to 60s.

[0015] In one embodiment, the adhesive includes one or more of epoxy resin adhesives, phenolic resin adhesives, phenolic epoxy resin adhesives, cyanate ester adhesives, silicone resin adhesives, aromatic polyamine adhesives, acid anhydride adhesives, dicyandiamide adhesives, and hydrazide adhesives.

[0016] In one embodiment, the mass of the adhesive is 2% to 5% of the mass of the magnetic material.

[0017] Furthermore, a molded inductor is prepared by the method for preparing a molded inductor according to any of the above embodiments.

[0018] In the method for preparing the integrally molded inductor provided in the above embodiments, a portion of the binder is cured before the magnetic composite material is hot-pressed. Experimental tests have shown that curing a portion of the binder before hot-pressing the magnetic composite material can effectively improve the insulation resistance value of the final integrally molded inductor.

[0019] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Detailed Implementation

[0020] To facilitate understanding of this application, a more complete description will be provided below. Preferred embodiments of this application are shown herein. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0023] According to one embodiment of this disclosure, a method for fabricating a molded inductor includes the following steps:

[0024] Magnetic composite materials are prepared by mixing thermosetting adhesives, solvents, and magnetic material powders.

[0025] The magnetic composite material is baked to remove the solvent, and then placed in a hot press mold for preheating and hot pressing.

[0026] Before hot-pressing the magnetic composite material, the adhesive is partially cured. Thermosetting adhesives are those containing active functional groups that undergo cross-linking reactions between molecules when heated. Thermosetting significantly reduces the overall fluidity of the adhesive. Partial curing refers to controlling external conditions to induce incomplete curing of the adhesive. This increases its viscosity and reduces its fluidity, but the adhesive is not fully cured, allowing for further shaping during hot pressing.

[0027] Experimental tests revealed that curing part of the binder before hot-pressing the magnetic composite material can effectively improve the insulation resistance value of the final integrally molded inductor.

[0028] Through extensive inventive experiments, the inventors of this disclosure discovered that the reason why the hot pressing process significantly reduces the insulation resistance of the integrally molded inductor is that a high temperature is applied to the magnetic composite material during the pressing process, while the viscosity of the binder decreases with increasing temperature. During hot pressing, the viscosity of the binder is at a low level, which makes it easy for the binder to be squeezed from the surface of the powder into the gaps in the powder. As a result, there is a lack of binder barrier between adjacent powder particles in the final integrally molded inductor, which in turn leads to a significant reduction in the insulation resistance of the integrally molded inductor.

[0029] To overcome this problem, the above embodiments of this disclosure employ a technical concept of partially curing the binder before hot-pressing the magnetic composite material. Specifically, by partially curing the binder first, the viscosity of the binder located between the magnetic material powders increases and its fluidity decreases, making it more difficult for it to be heated and displaced into the gaps between the magnetic material powders during hot-pressing. Since the binder still separates adjacent magnetic material powders, the insulation resistance value of the integrally molded inductor can be effectively improved.

[0030] In some specific examples of this embodiment, the adhesive may include one or more of epoxy resin adhesives, phenolic resin adhesives, phenolic epoxy resin adhesives, cyanate ester adhesives, silicone resin adhesives, aromatic polyamine adhesives, acid anhydride adhesives, dicyandiamide adhesives, and hydrazide adhesives.

[0031] In some specific examples of this embodiment, before hot pressing the magnetic composite material, a portion of the adhesive is cured during at least one of baking and preheating processes.

[0032] Traditional baking processes are generally only used to remove solvents from magnetic composite materials. To prevent the binder from becoming integrally formed with the magnetic material powder during hot pressing, the baking temperature is typically controlled below 60°C and the baking time is controlled within 60 minutes to prevent the binder from curing. The embodiments of this disclosure employ a technical concept of pre-curing part of the binder. It can be understood that during the baking process of the above embodiments, the baking temperature can be appropriately increased to the curing temperature of the thermosetting binder to allow partial curing of the thermosetting binder. For example, in some specific examples of this embodiment, the method of partially curing the binder includes controlling the baking temperature of the baking process to 65°C to 120°C. By increasing the baking temperature to 65°C to 120°C, the binder can begin to undergo a curing reaction, resulting in partial curing.

[0033] If the baking temperature is too high when partially curing the adhesive, the adhesive may become over-cured, increasing the difficulty of subsequent hot pressing. In some specific examples of this embodiment, the method of partially curing the adhesive includes controlling the baking temperature of the baking process to 65°C to 90°C. For example, the baking temperature of the baking process can be controlled to be 65°C, 70°C, 80°C, 90°C, or a range between these baking temperatures. By controlling the baking temperature of the baking process to 65°C to 90°C, the degree of curing of the adhesive can be controlled to be relatively weak, allowing the adhesive to still deform during the hot pressing process and form together with the magnetic material powder.

[0034] It is understood that, under the baking temperature conditions of the above embodiments, the baking time can be appropriately extended to allow partial curing of the adhesive. For example, in some specific examples of this embodiment, the method of partially curing the adhesive includes controlling the baking time of the baking process to be 60 min to 180 min. By appropriately extending the baking time, partial curing of the adhesive can also be achieved, thereby improving the insulation resistance value of the integrally molded inductor.

[0035] It is understood that the baking time should not be too long, otherwise the overall curing degree of the adhesive will be too high, which is not conducive to the molding of the subsequent hot pressing process. In some specific examples of this embodiment, the method of partially curing the adhesive includes controlling the baking time of the baking process to be 60 min to 150 min. For example, the baking time of the baking process can be controlled to be 60 min, 80 min, 100 min, 120 min, 150 min, or a range between these baking times.

[0036] Preheating refers to the process of placing the magnetic composite material, after baking to remove the solvent, into a hot press mold and preheating it to the hot pressing temperature. In some specific examples of the above embodiments, the preheating temperature is controlled between 160°C and 200°C. The traditional purpose of preheating is to reduce the viscosity of the adhesive and improve its fluidity, facilitating its shaping during hot pressing. To prevent the adhesive from curing before hot pressing, the traditional preheating time is typically controlled to be less than 10 seconds.

[0037] In some specific examples of the above embodiments, the method of partially curing the adhesive includes controlling the preheating time of the preheating process to be 20s to 150s. By appropriately extending the preheating time, partial curing of the adhesive can also be achieved, thereby increasing the insulation resistance value of the integrally molded inductor.

[0038] It is understandable that the preheating treatment time should not be too long. Optionally, methods to induce partial curing of the adhesive include controlling the preheating time of the preheating process to be between 20s and 60s. For example, controlling the preheating time of the preheating process to be 20s, 30s, 40s, 50s, 60s, or a range between these preheating times.

[0039] In other specific examples of this embodiment, additional curing steps can be added to partially cure the thermosetting adhesive in the magnetic composite material. However, more preferably, by changing the baking temperature and duration, or changing the preheating duration, the manufacturing process of the integrally molded inductor can be kept essentially unchanged, thus avoiding additional costs.

[0040] In some specific examples of this embodiment, acetone can be used as the solvent in the preparation of the magnetic composite material.

[0041] In some specific examples of this embodiment, the magnetic material powder is a soft magnetic material during the preparation of the magnetic composite material.

[0042] In traditional hot pressing processes, the binder is easily squeezed from the powder surface into the powder's voids, and the coating layer of the soft magnetic material can be directly damaged by pressure. This leads to a decrease in insulation resistance, which is particularly pronounced in soft magnetic materials with coatings. The preparation method provided in the above embodiments of this disclosure is particularly suitable for improving the insulation resistance performance of soft magnetic materials with coatings. In some specific examples of this embodiment, the magnetic material powder can also be a coated soft magnetic material during the preparation of the magnetic composite material.

[0043] In some specific examples of this embodiment, the mass of the adhesive is 2% to 5% of the mass of the magnetic material.

[0044] Another embodiment of this disclosure provides a molded inductor, which is prepared by the method for preparing a molded inductor in any specific example of the above embodiments.

[0045] To facilitate understanding of the advantages and implementation of the above-described method for fabricating a molded inductor, this disclosure also provides the following embodiments and comparative examples. Through performance comparisons of the embodiments and comparative examples, the advantages of the molded inductor fabrication method of this disclosure will become more apparent.

[0046] Unless otherwise specified, the materials used in the embodiments and comparative examples are available from the market, and the materials and processes with the same names used in the embodiments and comparative examples are exactly the same.

[0047] The magnetic material powder used in the following examples and comparative examples is a soft magnetic material powder with a coating layer. The preparation method is as follows: First, the iron-silicon-chromium soft magnetic powder is subjected to phosphating coating treatment. The mass of the phosphating coating layer is 0.3% of the powder mass. The phosphating coating treatment process is as follows: First, acetone and phosphoric acid are mixed and added to the powder. The mixture is stirred at 60°C until dry. The obtained powder is then mixed and dispersed evenly with carbonyl iron powder at a mass ratio of 8:2 to obtain a soft magnetic material powder with a coating layer.

[0048] The adhesive used is a cyanate ester adhesive, specifically bisphenol A cyanate ester, which includes: bisphenol A cyanate ester: diaminodiphenylmethane (DDM curing agent): dimethylimidazole = 100:8:0.5 (mass ratio).

[0049] Example 1

[0050] The soft magnetic material powder, binder and acetone are mixed in a mass ratio of 100:3:12, stirred evenly and then granulated to form a magnetic composite material.

[0051] The prepared magnetic composite material was placed in an oven and baked at a temperature of 70°C for 60 minutes to completely dry the magnetic composite material into powder.

[0052] Magnetic composite material powder was placed in a hot press mold and subjected to preheating and hot pressing to prepare a magnetic ring with an inner diameter of 8 mm and an outer diameter of 14 mm. During the preheating process, the mold temperature was controlled at 180℃ and the preheating time was controlled at 10 s. After the preheating process, hot pressing was performed, with the pressure controlled at 2.2 T, the holding time at 30 s, and the pressing height at 3.3 mm. Subsequently, it was baked at 180℃ for 1 hour to allow it to fully solidify and form.

[0053] Example 2

[0054] The soft magnetic material powder, binder and acetone are mixed in a mass ratio of 100:3:12, stirred evenly and then granulated to form a magnetic composite material.

[0055] The prepared magnetic composite material was placed in an oven and baked at a temperature of 80°C for 60 minutes to completely dry the magnetic composite material into powder.

[0056] Magnetic composite powder was placed in a hot press mold and subjected to preheating and hot pressing to prepare a magnetic ring with an inner diameter of 8 mm and an outer diameter of 14 mm. During the preheating process, the mold temperature was controlled at 180℃ and the preheating time was controlled at 10 s. After the preheating process, hot pressing was performed, with the pressure controlled at 2.5T, the holding time at 30 s, and the pressing height at 3.3 mm. Subsequently, it was baked at 180℃ for 1 hour to allow it to fully solidify and form.

[0057] Example 3

[0058] The soft magnetic material powder, binder and acetone are mixed in a mass ratio of 100:3:12, stirred evenly and then granulated to form a magnetic composite material.

[0059] The prepared magnetic composite material was placed in an oven and baked at a temperature of 90°C for 60 minutes to completely dry the magnetic composite material into powder.

[0060] Magnetic composite powder was placed in a hot press mold and subjected to preheating and hot pressing to prepare a magnetic ring with an inner diameter of 8 mm and an outer diameter of 14 mm. During the preheating process, the mold temperature was controlled at 180℃ and the preheating time was controlled at 10 s. After the preheating process, hot pressing was performed, with the pressure controlled at 2.8 T, the holding time at 30 s, and the pressing height at 3.3 mm. Subsequently, it was baked at 180℃ for 1 hour to allow it to fully solidify and form.

[0061] Example 4

[0062] The soft magnetic material powder, binder and acetone are mixed in a mass ratio of 100:3:12, stirred evenly and then granulated to form a magnetic composite material.

[0063] The prepared magnetic composite material was placed in an oven and baked at a temperature of 100°C for 60 minutes to completely dry the magnetic composite material into powder.

[0064] Magnetic composite powder was placed in a hot press mold and subjected to preheating and hot pressing to prepare a magnetic ring with an inner diameter of 8 mm and an outer diameter of 14 mm. During the preheating process, the mold temperature was controlled at 180℃ and the preheating time was controlled at 10 s. After the preheating process, hot pressing was performed, with the pressure controlled at 2.5T, the holding time at 30 s, and the pressing height at 3.3 mm. Subsequently, it was baked at 180℃ for 1 hour to allow it to fully solidify and form.

[0065] Example 5

[0066] The soft magnetic material powder, binder and acetone are mixed in a mass ratio of 100:3:12, stirred evenly and then granulated to form a magnetic composite material.

[0067] The prepared magnetic composite material was placed in an oven and baked at a temperature of 60°C for 60 minutes to completely dry the magnetic composite material into powder.

[0068] Magnetic composite powder was placed in a hot press mold and subjected to preheating and hot pressing to prepare a magnetic ring with an inner diameter of 8 mm and an outer diameter of 14 mm. During the preheating process, the mold temperature was controlled at 180℃ and the preheating time was controlled at 30 s. After the preheating process, hot pressing was performed, with the pressure controlled at 2.1 T, the holding time at 30 s, and the pressing height at 3.3 mm. Subsequently, it was baked at 180℃ for 1 hour to allow it to fully solidify and form.

[0069] Example 6

[0070] The soft magnetic material powder, binder and acetone are mixed in a mass ratio of 100:3:12, stirred evenly and then granulated to form a magnetic composite material.

[0071] The prepared magnetic composite material was placed in an oven and baked at a temperature of 60°C for 60 minutes to completely dry the magnetic composite material into powder.

[0072] Magnetic composite powder was placed in a hot press mold and subjected to preheating and hot pressing to prepare a magnetic ring with an inner diameter of 8 mm and an outer diameter of 14 mm. During the preheating process, the mold temperature was controlled at 180℃ and the preheating time was controlled at 60 s. After the preheating process, hot pressing was performed, with the pressure controlled at 2.3 T, the holding time at 30 s, and the pressing height at 3.3 mm. Subsequently, it was baked at 180℃ for 1 hour to allow it to fully solidify and form.

[0073] Example 7

[0074] The soft magnetic material powder, binder and acetone are mixed in a mass ratio of 100:3:12, stirred evenly and then granulated to form a magnetic composite material.

[0075] The prepared magnetic composite material was placed in an oven and baked at a temperature of 60°C for 60 minutes to completely dry the magnetic composite material into powder.

[0076] Magnetic composite material powder was placed in a hot press mold and subjected to preheating and hot pressing to prepare a magnetic ring with an inner diameter of 8 mm and an outer diameter of 14 mm. During the preheating process, the mold temperature was controlled at 180℃ and the preheating time was controlled at 90 s. After the preheating process, hot pressing was performed, with the pressure controlled at 2.5T, the holding time at 30 s, and the pressing height at 3.3 mm. Subsequently, it was baked at 180℃ for 1 hour to allow it to fully solidify and form.

[0077] Example 8

[0078] The soft magnetic material powder, binder and acetone are mixed in a mass ratio of 100:3:12, stirred evenly and then granulated to form a magnetic composite material.

[0079] The prepared magnetic composite material was placed in an oven and baked at a temperature of 60°C for 90 minutes to completely dry the magnetic composite material into powder.

[0080] Magnetic composite material powder was placed in a hot press mold and subjected to preheating and hot pressing to prepare a magnetic ring with an inner diameter of 8 mm and an outer diameter of 14 mm. During the preheating process, the mold temperature was controlled at 180℃ and the preheating time was controlled at 10 s. After the preheating process, hot pressing was performed, with the pressure controlled at 2.2 T, the holding time at 30 s, and the pressing height at 3.3 mm. Subsequently, it was baked at 180℃ for 1 hour to allow it to fully solidify and form.

[0081] Example 9

[0082] The soft magnetic material powder, binder and acetone are mixed in a mass ratio of 100:3:12, stirred evenly and then granulated to form a magnetic composite material.

[0083] The prepared magnetic composite material was placed in an oven and baked at a temperature of 90°C for 60 minutes to completely dry the magnetic composite material into powder.

[0084] Magnetic composite powder was placed in a hot press mold and subjected to preheating and hot pressing to prepare a magnetic ring with an inner diameter of 8 mm and an outer diameter of 14 mm. During the preheating process, the mold temperature was controlled at 180℃ and the preheating time was controlled at 30 s. After the preheating process, hot pressing was performed, with the pressure controlled at 2.4 T, the holding time at 30 s, and the pressing height at 3.3 mm. Subsequently, it was baked at 180℃ for 1 hour to allow it to fully solidify and form.

[0085] Comparative Example 1

[0086] The soft magnetic material powder, binder and acetone are mixed in a mass ratio of 100:3:12, stirred evenly and then granulated to form a magnetic composite material.

[0087] The prepared magnetic composite material was placed in an oven and baked at a temperature of 60°C for 60 minutes to completely dry the magnetic composite material into powder.

[0088] Magnetic composite material powder was placed in a hot press mold and subjected to preheating and hot pressing to prepare a magnetic ring with an inner diameter of 8 mm and an outer diameter of 14 mm. During the preheating process, the mold temperature was controlled at 180℃ and the preheating time was controlled at 10 s. After the preheating process, hot pressing was performed, with the pressure controlled at 2T, the holding time at 30 s, and the pressing height at 3.3 mm. Subsequently, it was baked at 180℃ for 1 hour to allow it to fully solidify and form.

[0089] The insulation resistance and permeability of the above embodiments and comparative examples were tested, and the results are shown in Table 1.

[0090] Table 1

[0091] Magnetic permeability (H / m) Insulation resistance (MΩ) Example 1 33.8 203.5 Example 2 32.6 595.4 Example 3 32.0 1893.2 Example 4 29.8 5328 Example 5 33.6 358.7 Example 6 31.7 2390 Example 7 28.6 6342 Example 8 34.0 329 Example 9 31.5 12980 Comparative Example 1 35.6 3.2

[0092] The pressures in each embodiment and comparative example are slightly different. The main purpose is to adjust the pressure so that the thickness of the prepared magnetic rings is consistent, and to avoid pressure differences caused by density differences in the magnetic rings.

[0093] Referring to Table 2, the baking temperatures of Examples 1 to 4 were significantly higher than those of Comparative Example 1, the preheating times of Examples 5 to 7 were significantly higher than those of Comparative Example 1, the baking time of Example 8 was also higher than that of Comparative Example 1, and both the baking temperature and preheating time of Example 9 were higher than those of Comparative Example 1. All of these resulted in a significant increase in the insulation resistance value of the integrally molded inductor. This is mainly because the preparation methods of each example cured part of the binder before hot pressing, thus significantly improving the insulation resistance value of the prepared magnetic ring. However, based on Examples 4 and 7, it can be seen that when the curing temperature is too high or the preheating time is too long, it can also lead to a significant decrease in magnetic permeability.

[0094] Please note that the above embodiments are for illustrative purposes only and do not imply any limitation on this application.

[0095] It should be understood that, unless otherwise expressly stated herein, there is no strict order in which the steps are executed, and these steps may be executed in other orders. Moreover, at least some of the steps may include multiple sub-steps or multiple stages, which are not necessarily completed at the same time, but may be executed at different times, and the execution order of these sub-steps or stages is not necessarily sequential, but may be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0096] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0097] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A method for fabricating a one-piece molded inductor, characterized in that, The method comprises the following steps: mixing a thermosetting adhesive, a solvent and a magnetic material powder to prepare a magnetic composite material; baking the magnetic composite material to remove the solvent, and then placing the magnetic composite material in a hot-pressing mold to perform preheating and hot-pressing treatment; wherein, before the hot-pressing treatment of the magnetic composite material, part of the adhesive is cured; the curing of part of the adhesive includes controlling the preheating temperature of the preheating treatment to be 160-200 ℃, controlling the preheating time of the preheating treatment to be 20-150 s, or controlling the baking temperature of the baking treatment to be 65-120 ℃.

2. The method of claim 1, wherein the method further comprises: the curing of part of the adhesive includes controlling the baking temperature of the baking treatment to be 65-90 ℃.

3. The method of claim 1, wherein the method further comprises: controlling the baking time of the baking treatment to be 60-180 min.

4. The method of claim 3, wherein the method further comprises: controlling the baking time of the baking treatment to be 60-150 min.

5. The method of claim 1, wherein the method further comprises: the curing of part of the adhesive includes controlling the preheating time of the preheating treatment to be 20-60 s.

6. The method of manufacturing a one-piece inductor according to any one of claims 1 to 5, wherein the adhesive includes one or more of an epoxy resin adhesive, a phenol resin adhesive, a phenol epoxy resin adhesive, a cyanate ester adhesive, a silicone resin adhesive, an aromatic polyamine adhesive, an acid anhydride adhesive, a dicyandiamide adhesive and a hydrazide adhesive.

7. The method of claim 1 to 5, wherein the method is characterized by, the mass of the adhesive is 2-5% of the mass of the magnetic material.

8. The method of claim 6, wherein the method further comprises: the mass of the adhesive is 2-5% of the mass of the magnetic material.

9. An integrally formed inductor, characterized by obtained by the method for manufacturing a one-piece inductance according to any one of claims 1-8.