Manufacturing method of inductor with copper-embedded magnetic core and inductor

Abstract

The invention relates to the field of inductor manufacturing, in particular to a manufacturing method of an inductor with a copper-embedded magnetic core and the inductor. The method comprises the following steps: preparing a soft magnetic material and a copper conductor; secondly, pressing the soft magnetic material into an integral magnetic core preform through a cold pressing process; then, the copper conductor is embedded into the mounting groove in the pressing direction, and an inductor prefabricated body is formed; and finally, carrying out secondary pressing on the inductor prefabricated body by using a hot pressing process, so that the copper conductor and the magnetic core prefabricated body are tightly combined to form a final inductor body. Through innovative design, the magnetic core prefabricated body is arranged to be of an integral structure, the mounting groove matched with the copper conductor is reserved in the magnetic core prefabricated body, and then hot-pressing combination is conducted. The method not only maintains the characteristics of the product, but also improves the yield and reduces the cost.

Description

Technical Field

[0001] The present application relates to the field of inductor manufacturing, and particularly to a manufacturing method and an inductor of a magnetic core embedded copper inductor. Background Art

[0002] The magnetic core embedded copper inductor is a high-performance inductor component that combines the advantages of magnetic core materials and embedded copper conductors and is widely used in high-frequency and high-power scenarios. Structurally, the magnetic core provides high magnetic permeability to concentrate magnetic flux, while the embedded copper conductor forms a low-resistance coil, optimizing current distribution and reducing the skin effect.

[0003] The existing manufacturing methods of magnetic core embedded copper inductors have technical problems of high cost and low yield. Summary of the Invention

[0004] The present application provides a manufacturing method and an inductor of a magnetic core embedded copper inductor, aiming to improve the yield and reduce the cost while maintaining the product characteristics.

[0005] The technical solution of the present application is as follows:

[0006] In a first aspect, the present application provides a manufacturing method of a magnetic core embedded copper inductor, including the following steps:

[0007] S1) Prepare soft magnetic material and copper conductor

[0008] The soft magnetic material is soft magnetic alloy powder doped with glue material

[0009] The copper conductor includes a first component part, a second component part, and a third component part connected in sequence. The first component part and the third component part are bent towards the same direction relative to the second component part. The included angle between the first component part and the second component part is α1, and the included angle between the third component part and the second component part is α2, where 90° ≤ α1 ≤ 180° and 90° ≤ α2 ≤ 180°;

[0010] S2) Manufacture a magnetic core preform

[0011] Press the soft magnetic material through a cold pressing process to form an integral magnetic core preform. Along the pressing direction, the magnetic core preform includes a first surface and a second surface that are parallel to each other, and an installation groove is formed in the magnetic core preform. The installation groove includes a transverse groove, a first vertical groove, and a second vertical groove. The transverse groove opens on the first surface and extends in a direction parallel to the first surface. The first vertical groove and the second vertical groove are connected to both ends of the transverse groove. The extending directions of the first vertical groove and the second vertical groove are perpendicular to the first surface and penetrate from the first surface to the second surface.

[0012] S3) Implant the copper conductor

[0013] Along the pressing direction, the copper conductor is implanted into the installation groove to form an inductor preform. Among them, the second component is embedded in the horizontal groove, the first component is inserted into the first vertical groove, and the third component is inserted into the second vertical groove. The part of the copper conductor in the installation groove is in contact with the groove wall of the installation groove. S4) The inductor preform formed in step S3) is pressed for the second time using a hot pressing process, so that the copper conductor and the magnetic core preform are tightly combined to form the inductor body. After subsequent processing, the finished inductor is obtained. The pressing direction in the hot pressing process is the same as the pressing direction in the cold pressing process.

[0014] Based on the manufacturing method of a magnetic core embedded copper inductor provided in the first aspect, a relatively mature cold pressing and hot pressing process is adopted to improve the yield of the product. And through ingenious conception, the magnetic core preform is set as an integrated structure, and an installation groove compatible with the copper conductor is formed in the integrated magnetic core preform. In this way, when the hot pressing process is used for secondary pressing, the magnetic core preform with a certain structural strength can prevent the copper sheet from shaking and tilting in the magnetic core preform, thereby improving the electrical performance. In addition, for the production of the same inductor, there are no multiple magnetic core preforms. In this way, there is no phenomenon of different densities of multiple magnetic core preforms, which is conducive to avoiding the occurrence of cracks or cracking at the joints of multiple magnetic core preforms, and in the finished inductor, the density of the magnetic core is uniform, which is conducive to improving the electrical performance of the inductor. The present application adopts an integrated magnetic core preform, and for the same inductor, only one cold pressing and one hot pressing are required. In the prior art, multiple magnetic core preforms require multiple cold pressings. Therefore, compared with the prior art, the inductor manufacturing method of the present application significantly improves the manufacturing efficiency and shortens the manufacturing time.

[0015] In a possible design, in step S3), the surface of the second component facing away from the bending direction of the first component is flush with the first surface.

[0016] Based on the manufacturing method of the inductor provided in this embodiment, after the copper conductor is placed in the installation slot, the surface of the second component of the copper conductor that is away from the bending direction of the first component is flush with the first surface, so that during the secondary pressing process in step S4), the copper conductor and the integrated prefabricated magnetic core can be subjected to the same pressure at the same time. This uniform pressure not only ensures a close connection between the two, but also effectively reduces the contact resistance and improves the overall electrical performance.

[0017] In a possible design, in step S3), one end of the first component away from the first surface extends out of the first vertical groove, and one end of the third component away from the first surface extends out of the second vertical groove.

[0018] Based on the manufacturing method of the inductor provided by this embodiment, after the copper conductor is placed in the mounting groove, one end of the first component away from the first surface extends out of the first vertical groove, and one end of the third component away from the first surface extends out of the second vertical groove. After pressing, the magnetic flux area of the product can be increased, thereby improving the inductance value of the product and achieving optimization in design.

[0019] In a possible design, in step S2), in the cold pressing process, a gradient pressure is adopted, which successively includes a pre-pressing stage, a main pressing stage, and a final pressing stage. The pressure per unit area in the pre-pressing stage is 2.5 - 3.7 T / cm 2 , the pressure per unit area in the main pressing stage is 5.0 - 7.5 T / cm 2 , and the pressure per unit area in the final pressing stage is 8.7 - 10.0 T / cm 2 .

[0020] Based on the manufacturing method of the inductor provided by this embodiment, in the cold pressing process, the gradient pressure is mainly used to increase the density of the magnetic core preform. The higher the density of the magnetic core, the lower the loss of the product. At the same time, it can better ensure the magnetic flux density, and the electrical properties and structure of the magnetic core are more stable.

[0021] In a possible design, in step S4), in the hot pressing process, a gradient pressure is adopted, including a pressure preheating stage and a main pressing stage.

[0022] The pressure preheating stage is used to soften the adhesive in the soft magnetic material, and through the preliminary pressure, the soft magnetic material can better fill the mold and expel air.

[0023] The pressure in the main pressing stage is greater than the preliminary pressure, and the temperature in the main pressing stage is higher than that in the pressure preheating stage. It is used to further compress the soft magnetic alloy powder, promote the mechanical interlocking and plastic deformation between the soft magnetic alloy powders, and complete the dynamic recrystallization and dense bonding of the soft magnetic alloy powders.

[0024] Based on the manufacturing method of the inductor provided by this embodiment, a preliminary pressure is applied during the preheating process. This pressure is relatively gentle, enabling the magnetic powder to better fill the mold and reducing the voids between particles. This process not only helps to expel air as much as possible but also avoids the formation of pores or delamination defects due to the compression of the residual air in the soft magnetic alloy powder during the subsequent compression process. In addition, since the preliminary pressure has been used before the main pressing stage, it is possible to significantly reduce the density mutation during the main pressing stage, thereby effectively reducing the internal stress concentration and ensuring the structural stability and performance consistency of the final product.

[0025] In a possible design, in step S4), after the main pressing stage, a slow release stage is further included. The pressure in the slow release stage is less than that in the main pressing stage, and the temperature in the slow release stage is less than that in the main pressing stage, which is used to reduce the pressure, lower the temperature before demolding, and reduce the release of internal stress.

[0026] Based on the manufacturing method of the inductor provided by this embodiment, in the slow release stage, by gradually reducing the pressure and simultaneously reducing the temperature, the release of internal stress can be slowly reduced, the cracking of the product and the expansion after demolding can be reduced, and the density, size, etc. of the product can be stabilized as much as possible, thereby improving the overall quality and performance of the product.

[0027] In a possible design, the pressure per unit area in the pressure preheating stage is 7.5 - 10.0 T / cm 2 , the pressure per unit area in the main pressing stage is 11.2 - 15.0 T / cm 2 , and the pressure per unit area in the slow release stage is 5.0 - 7.5 T / cm 2 .

[0028] Based on the manufacturing method of the inductor provided by this embodiment, the manufactured inductor has a relatively high density, good inductance value and yield.

[0029] In a possible design, the subsequent processes include primary spraying and secondary spraying on the inductor body.

[0030] The material for the primary spraying is an insulating material, and the material for the secondary spraying is a conductive material.

[0031] Based on the manufacturing method of the inductor provided by this embodiment, the second spraying uses a conductive material, such as a material containing carbon nanotubes and graphene. These materials can enhance the magnetic shielding effect of the product, reduce magnetic field leakage, and improve the performance stability of the product.

[0032] In a possible design, after the secondary spraying, there are also steps of peeling off part of the sprayed coating at the corresponding position on the first surface to expose at least part of the copper conductor, and electroplating at the peeled part of the sprayed coating.

[0033] Based on the manufacturing method of the inductor provided by this embodiment, in this application, after the secondary spraying, part of the coating is peeled off at the corresponding position on the first surface to expose at least part of the copper conductor, and electroplating treatment is performed on it. In this way, the heat dissipation performance of the inductor can be enhanced, the remaining loss can be effectively reduced, and the overall efficiency and stability can be improved.

[0034] In the second aspect, based on the same inventive concept, this application also provides an inductor manufactured by the manufacturing method of the above-mentioned magnetic core copper-embedded inductor. For the beneficial effects of the inductor provided in the above second aspect, reference can be made to the beneficial effects brought by the above first aspect and each possible embodiment of the first aspect, which will not be elaborated here. Description of the Drawings

[0035] Figure 1 This is a schematic structural diagram of the copper conductor prepared in step S1) provided by the embodiment of the present application.

[0036] Figure 2 This is a three-dimensional structural diagram of the magnetic core preform formed in step S2).

[0037] Figure 3 is Figure 2 the top view of.

[0038] Figure 4 is Figure 3 the A-A sectional view of.

[0039] Figure 5 This is a schematic diagram of the state of implanting the copper conductor in step S3).

[0040] Figure 6 This is a schematic structural diagram of the inductor body formed in step S4).

[0041] Figure 7 This is a schematic structural diagram of the inductor body after the first spraying and the second spraying.

[0042] Figure 8 This is a schematic structural diagram of the inductor body with a part of the coating peeled off at the corresponding position on the first surface of the magnetic core, exposing a part of the copper conductor.

[0043] Figure 9 This is a schematic structural diagram of the inductor body after electroplating at the coating peeling site.

[0044] Figure 10 is Figure 1 the front view of the copper conductor shown.

[0045] Figure 11 is Figure 1 the top view of the copper conductor shown.

[0046] Among them, the reference numerals are:

[0047] 1. Copper conductor; 11. First component; 12. Second component; 13. Third component;

[0048] 2. Magnetic core preform; 2A. First surface; 2B. Second surface; 21. Horizontal groove; 22. First vertical groove; 23. Second vertical groove;

[0049] 3. Inductor body; 4. Spray coating; 5. Electroplated layer. Detailed Description of the Invention

[0050] To make the objectives, technical solutions and advantages of the embodiments of this application clearer, the following will, with reference to the accompanying drawings in the embodiments of this application, clearly and completely describe the technical solutions in the embodiments of this application. Apparently, the described embodiments are some but not all of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of this application without creative efforts shall fall within the scope of protection of this application.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the description and claims of this application and the drawings are intended to cover non-exclusive inclusion.

[0052] Reference to "embodiment" herein means that a particular feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0053] The following will elaborate on the technical solutions of this application starting from the background art of this application.

[0054] Currently, the magnetic core embedded copper inductor is mainly manufactured by the co-firing technology of copper and iron. The specific steps are as follows: First, implant the copper conductor into the mold, then fill the soft magnetic material and press it to form. Then sinter it in a high-temperature furnace, and subsequently perform impregnation and baking treatments on the product. Next, grind the product size to the required specifications, and successively perform processes such as spraying, paint stripping, electroplating, bonding, and electrical performance testing.

[0055] The main deficiencies of this process are as follows:

[0056] 1) The process is not yet mature, and the current market through-yield is approximately 50% - 70%.

[0057] 2) The product is prone to cracking after high-temperature sintering.

[0058] 3) During pressing, the soft magnetic material and the copper sheet are simultaneously pressed into shape. Analyzing from the side, the copper sheet is prone to tilting, affecting its magnetic circuit and resulting in unstable electrical properties of the product.

[0059] 4) The raw material cost is relatively high (soft magnetic materials such as iron-nickel and iron-silicon-aluminum are mainly used in the market).

[0060] 5) Hazardous gases are used, such as hydrogen.

[0061] In another prior art, the production of the copper-embedded core inductor is carried out through a cold pressing process and a hot pressing process. Specifically, a plurality of core preforms are respectively produced through the cold pressing process, and the copper conductor is combined with the plurality of core preforms through the hot pressing process. This technology uses a plurality of core preforms, and the densities of the plurality of core preforms will be different. Thus, the following adverse effects will be brought:

[0062] 1) During the hot pressing process of core preforms with different densities, cracks and fractures are likely to occur at the bonding parts.

[0063] 2) The number of core preforms is large, the combination difficulty is high, and the dimensional accuracy requirements for the core preforms and the copper conductor are high.

[0064] 3) The same inductor has cores with multiple different densities, and the characteristics of the inductor are unstable and fluctuate greatly.

[0065] In view of the disadvantages of low yield, high cost or unstable inductor characteristics in the existing copper-embedded core inductors, this application proposes an improved manufacturing method, aiming to reduce the manufacturing difficulty and cost while maintaining the product characteristics.

[0066] Figure 1 It is a schematic structural diagram of the copper conductor prepared in step S1) provided by the embodiment of this application. Figure 2 It is a schematic three-dimensional structure diagram of the core preform formed in step S2). Figure 3 For Figure 2 the top view. Figure 4 For Figure 3 the A-A sectional view. Figure 5 It is a schematic diagram of the state of implanting the copper conductor in step S3). Figure 6 It is a schematic structural diagram of the inductor body formed in step S4).

[0067] Please refer to Figures 1 to 6 The manufacturing method of the copper-embedded core inductor provided by this application includes the following steps:

[0068] S1) Prepare soft magnetic material and copper conductor 1

[0069] The soft magnetic material is soft magnetic alloy powder doped with a binder.

[0070] The copper conductor 1 includes a first component part 11, a second component part 12, and a third component part 13 that are connected in sequence. The first component part 11 and the third component part 13 are bent toward the same direction with respect to the second component part 12. The included angle between the first component part 11 and the second component part 12 is α1, and the included angle between the third component part 13 and the second component part 12 is α2, where 90° ≤ α1 ≤ 180° and 90° ≤ α2 ≤ 180°.

[0071] S2) Fabricate the magnetic core preform 2

[0072] The soft magnetic material is pressed by a cold pressing process to form an integrated magnetic core preform 2. Along the pressing direction, the magnetic core preform 2 includes a first surface 2A and a second surface 2B that are parallel to each other, and an installation groove is formed in the magnetic core preform 2. The installation groove includes a transverse groove 21, a first vertical groove 22, and a second vertical groove 23. The transverse groove 21 opens on the first surface 2A and extends parallel to the first surface 2A. The first vertical groove 22 and the second vertical groove 23 are connected to both ends of the transverse groove 21. The extending directions of the first vertical groove 22 and the second vertical groove 23 are perpendicular to the first surface 2A and penetrate from the first surface 2A to the second surface 2B.

[0073] S3) Implant the copper conductor 1

[0074] Along the pressing direction, the copper conductor 1 is implanted into the installation groove to form an inductor preform. Among them, the second component part 12 is embedded in the transverse groove 21, the first component part 11 is inserted into the first vertical groove 22, and the third component part 13 is inserted into the second vertical groove 23. The part of the copper conductor 1 located in the installation groove is in contact with the groove wall of the installation groove.

[0075] S4) Using a hot pressing process, the inductor preform formed in step S3) is secondarily pressed so that the copper conductor 1 and the magnetic core preform 2 are tightly combined to form an inductor body 3. After subsequent process treatments, a finished inductor is obtained. The pressing direction in the hot pressing process is the same as the pressing direction in the cold pressing process.

[0076] Please combine Figures 1 to 6 , the manufacturing method of the magnetic core copper-embedded inductor provided by this application has the following characteristics:

[0077] 1. High yield: Compared with the copper-iron co-firing processing technology, this application adopts relatively mature processes such as cold pressing and hot pressing. The cold pressing process is a process of compacting soft magnetic material powder (such as iron-silicon, iron-nickel, amorphous or nanocrystalline alloy powder, etc.) into a predetermined shape using pressure. The hot pressing process is to simultaneously heat and pressurize through a hot press, so that the copper conductor 1 and the magnetic core preform 2 eliminate pores and enhance interface bonding under the thermo-mechanical coupling effect, improving density and performance. The overall process is relatively mature, and the straight-through yield is expected to reach 90% - 95%.

[0078] 2. Lower cost while maintaining product characteristics: The prices of iron-nickel alloy powder and iron-silicon alloy powder are relatively high, ranging from 150 to 300 yuan per kilogram, while the prices of amorphous or nanocrystalline alloy powder are relatively low, about 60 to 75 yuan per kilogram. The copper-iron process can better utilize the performance of iron-nickel alloy powder and iron-silicon alloy powder. When using iron-nickel alloy powder to manufacture an inductor through the copper-iron co-firing process, the efficiency can reach 70% to 75%. By using the method of the present application, an inductor can be manufactured using amorphous or nanocrystalline alloy powder, and the efficiency is about 66% to 72%, which is similar to the former. Therefore, under the condition that the product characteristics are basically the same, using the process of the present application can reduce costs.

[0079] 3. Stable product characteristics: A prominent feature of the manufacturing process provided by the present application is that through a clever concept, the magnetic core preform 2 is set as an integral structure, and an installation groove adapted to the copper conductor 1 is formed in the integral magnetic core preform 2. In this way, the following beneficial effects can be brought to the manufacturing of the copper-embedded inductor of the magnetic core and the characteristics of the finished inductor:

[0080] First: The magnetic core preform 2 is formed by a cold pressing process. After being pressed by the cold pressing process, the magnetic core preform 2 has a certain structural strength. When the copper conductor 1 is implanted and then subjected to secondary pressing by a hot pressing process, the magnetic core preform 2 with a certain structural strength can prevent the copper sheet from shaking and tilting inside the magnetic core preform 2, improving the electrical performance. In this way, the manufacturing method of the inductor provided by the present application has the advantage of preventing the copper sheet from tilting compared with the first prior art, which is beneficial to improving the electrical performance of the inductor.

[0081] Second, the magnetic core preform 2 is an integral magnetic core preform. For the manufacturing of the same inductor, there is no multiple magnetic core preforms. In this way, there is no phenomenon of different densities of multiple magnetic core preforms, which is beneficial to avoiding cracks or cracking at the joints of multiple magnetic core preforms. Moreover, in the finished inductor, the density of the magnetic core is uniform, and compared with the second prior art, it has the characteristic of stable inductor characteristics.

[0082] 4. Short production cycle and high production efficiency: The present application uses an integral magnetic core preform 2. For the same inductor, only one cold pressing and one hot pressing are required. In the prior art, multiple magnetic core preforms need to be cold pressed multiple times. Therefore, compared with the prior art, the inductor manufacturing method of the present application significantly improves the manufacturing efficiency and shortens the manufacturing time.

[0083] It should be noted that Figures 2 to 4 the shape of the magnetic core shown in

[0084] It should also be noted that the manufacturing method of the magnetic core embedded with copper for the present application can also be applicable to other products with similar structures. For example, in some cases, the material of the coil can also be made of other conductive metals, such as silver.

[0085] In an embodiment of the present application, in step S3), the surface 121 of the second component part 12 facing away from the bending direction of the first component part 11 is flush with the first surface 2A.

[0086] Specifically, please refer to Figure 5 and Figure 6 , when the copper conductor 1 is placed in the installation groove, the surface of the second component part 12 of the copper conductor 1 facing away from the bending direction of the first component part 11 is flush with the first surface 2A. In this way, during the secondary pressing process in step S4), the copper conductor 1 and the integrated prefabricated magnetic core can be simultaneously subjected to the same magnitude of pressure. This uniform pressure not only ensures the tight combination between the two, but also effectively reduces the contact resistance and improves the overall electrical performance. In addition, this synchronous pressing method can also avoid material deformation or damage caused by uneven pressure, thereby ensuring the stability and reliability of the product.

[0087] In an embodiment of the present application, in step S3), the end of the first component part 11 away from the first surface 2A extends out of the first vertical groove 22, and the end of the third component part 13 away from the first surface 2A extends out of the second vertical groove 23.

[0088] Specifically, please continue to refer to Figure 5 and Figure 6 , when the copper conductor 1 is placed in the installation groove, the end of the first component part 11 away from the first surface 2A extends out of the first vertical groove 22, and the end of the third component part 13 away from the first surface 2A extends out of the second vertical groove 23. That is to say, the height of the copper conductor 1 must be greater than the height of the magnetic core preform 2. After pressing, the magnetic flux area of the product can be increased (Φ = B·S, where Φ represents the magnetic flux, B represents the magnetic induction intensity, and S represents the area through which the magnetic lines of force pass), thereby increasing the inductance value of the product and achieving optimization in design.

[0089] In an embodiment of the present application, in step S2), the cold pressing process adopts gradient pressure, which successively includes a pre-pressing stage, a main pressing stage, and a final pressing stage. The pressure per unit area in the pre-pressing stage is 2.5 - 3.7 T / cm 2 , the pressure per unit area in the main pressing stage is 5.0 - 7.5 T / cm 2 , and the pressure per unit area in the final pressing stage is 8.7 - 10.0 T / cm 2 .

[0090] Specifically, in the cold pressing process, the gradient pressure is mainly used to increase the density of the magnetic core preform 2. The pre-pressing stage is used to initially remove the gaps between loose particles and reduce the porosity during subsequent pressing. The main pressing stage realizes material densification, and the final pressing stage stabilizes the size of the green compact and eliminates elastic aftereffect.

[0091] The higher the density of the magnetic core, the lower the loss of the product. At the same time, it can better ensure the magnetic flux density, and the electrical properties and structure of the magnetic core are more stable.

[0092] In addition, the gradient pressure helps to reduce the internal stress concentration and residual stress. Moreover, it is more compatible with the creep characteristics of the material, which is beneficial to improving the process stability.

[0093] In an embodiment of the present application, in step S4), the hot pressing process uses gradient pressure, including a pressure preheating stage and a main pressing stage.

[0094] The pressure preheating stage is used to soften the binder in the soft magnetic material, and through the initial pressure, the soft magnetic material can better fill the mold and remove air.

[0095] The pressure in the main pressing stage is greater than the initial pressure, and the temperature in the main pressing stage is greater than the temperature in the pressure preheating stage. It is used to further compress the soft magnetic alloy powder, promote the mechanical interlocking and plastic deformation between the soft magnetic alloy powders, and complete the dynamic recrystallization and dense combination of the soft magnetic alloy powders.

[0096] Specifically, an initial pressure is applied during the preheating process. This pressure is relatively mild, enabling the magnetic powder to better fill the mold and reducing the voids between particles. This process not only helps to expel air as much as possible but also avoids the formation of pores or delamination defects due to the compression of the residual air in the soft magnetic alloy powder during subsequent compression. In addition, since the initial pressure has been used before the main pressing stage, the density mutation in the main pressing stage can be significantly reduced, thereby effectively reducing the internal stress concentration and ensuring the structural stability and performance consistency of the final product.

[0097] In an embodiment of the present application, in step S4), after the main pressing stage, there is also a pressure relief stage. The pressure in the pressure relief stage is less than the pressure in the main pressing stage, and the temperature in the pressure relief stage is less than the temperature in the main pressing stage. It is used to reduce the pressure and temperature before demolding and reduce the release of internal stress.

[0098] Specifically, the pressure in the main pressing stage is relatively large, usually reaching 4 - 6T, and the temperature is relatively high, generally between 150 and 200 degrees Celsius. This enables the material to fully flow and fill the mold under high pressure and high temperature. In the pressure relief stage, by gradually reducing the pressure and simultaneously reducing the temperature, the release of internal stress can be slowly reduced, the cracking of the product and the expansion after demolding can be reduced, and the density, size, etc. of the product can be stabilized as much as possible, thereby improving the overall quality and performance of the product.

[0099] In an embodiment of the present application, the pressure per unit area in the pressurizing and preheating stage is 7.5 - 10.0 T / cm² 2 , and the pressure per unit area in the main pressing stage is 11.2 - 15.0 T / cm² 2 , and the pressure per unit area in the slow release stage is 5.0 - 7.5 T / cm² 2 .

[0100] It has been found in practice that when the machine pressure range in the preheating stage is 3.0 - 4.0 T, the machine pressure range in the main pressing stage is 4.5 - 6.0 T, and the machine pressure range in the slow release stage is 2.0 - 3.0 T, the inductors produced have a higher density, better inductance value and yield. The following specific embodiments can prove this.

[0101] In an embodiment of the present application, the subsequent processes include primary spraying and secondary spraying on the inductor body 3. The material for primary spraying is an insulating material, and the material for secondary spraying is a conductive material.

[0102] Specifically, after hot pressing, the manufacturing of the inductor further includes steps such as chamfering, spraying, grinding, paint stripping and electroplating. In the prior art, the spraying process only coats the surface of the inductor with insulating paint. While in the present application, it includes two sprayings. The second spraying uses conductive materials, such as materials containing carbon nanotubes and graphene. These materials can enhance the magnetic shielding effect of the product, reduce magnetic field leakage, and improve the performance stability of the product.

[0103] Figure 7 is a schematic structural diagram of the inductor body after primary spraying and secondary spraying. Please refer to Figure 6 and Figure 7 . It should be noted that both the first and second sprayings need to avoid the electrode surface, Figure 7 in which the spray coating layer 4 covers the copper conductor 1 exposed on the first surface 2A of the magnetic core. The first surface 2A of the magnetic core is the first surface 2A of the magnetic core preform 2 formed after hot pressing.

[0104] In an embodiment of the present application, after secondary spraying, it further includes the steps of stripping a part of the spray coating layer 4 at the corresponding position on the first surface 2A to expose at least part of the copper conductor 1, and electroplating at the stripped part of the spray coating layer 4.

[0105] Figure 8 is a schematic structural diagram of the inductor body with part of the spray coating layer stripped at the corresponding position on the first surface, exposing part of the copper conductor. Please refer to Figure 7 and Figure 8 . After stripping part of the spray coating layer 4, not only the copper conductor 1 is exposed, but also part of the magnetic core is exposed. Figure 9 is a schematic structural diagram of the inductor body after electroplating at the stripped part of the spray coating layer.

[0106] Please continue to refer to Figure 8 and Figure 9 , specifically, the heat dissipation effect of the metal material is restricted due to the insulating material covering the metal material. After the secondary spraying in this application, a part of the coating is peeled off at the corresponding position of the first surface 2A to expose at least part of the copper conductor 1, and electroplating treatment is performed on it to form an electroplated layer 5. In this way, the heat dissipation performance of the inductor can be enhanced, the residual loss can be effectively reduced, and the overall efficiency and stability can be improved.

[0107] Figure 10 For Figure 1 the front view of the copper conductor shown Figure 11 and Figure 1 the top view of the copper conductor shown. The following will be described in detail with reference to the attached Figures 1 - 6 , Figure 10 and 11 some specific embodiments of this application.

[0108] Embodiment 1:

[0109] J1) Determine the shape and size requirements of the copper conductor 1 and the shape and size requirements of the magnetic core preform 2.

[0110] Please combine Figure 1 , Figure 10 and Figure 11 , the copper conductor 1 includes a first component part 11, a second component part 12, and a third component part 13 connected in sequence. The first component part 11 and the third component part 13 are bent 90° in the same direction relative to the second component part 12. The overall length L of the copper conductor is 4.4 ± 0.05 mm, the height H is 3.55 ± 0.05 mm, the width W is 0.8 ± 0.03 mm, the length L1 of the first component part 11 and the third component part 13 is 1.1 ± 0.05 mm, and the distance D between the first component part 11 and the third component part 13 is 2.2 ± 0.05 mm.

[0111] The outer shape of the magnetic core preform 2 is a cuboid, with an overall length of 6.77 ± 0.01 mm, a width of 3.08 ± 0.005 mm, and a height of 3.25 ± 0.03 mm. An installation groove adapted to the copper conductor 1 is provided inside, and the installation groove penetrates through the first surface 2A and the second surface 2B of the two large areas of the cuboid opposite to each other. The shape of the installation groove is adapted to the copper conductor 1 and includes a horizontal groove 21, a first vertical groove 22, and a second vertical groove 23. The horizontal groove 21 opens on the first surface 2A, and the extension direction is parallel to the first surface 2A. The first vertical groove 22 and the second vertical groove 23 are connected to both ends of the horizontal groove 21, and the extension directions of the first vertical groove 22 and the second vertical groove 23 are perpendicular to the first surface 2A and penetrate from the first surface 2A to the second surface 2B.

[0112] The second component 12 of the copper conductor 1 can be embedded in the transverse groove 21, the first component 11 can be inserted into the first vertical groove 22, the third component 13 can be inserted into the second vertical groove 23, and the part of the copper conductor 1 located in the installation groove can be in contact with the groove wall of the installation groove.

[0113] J2) Determine the structure and dimensions of the die system used in the hot pressing process and the cold pressing process according to the shape and dimensions of the magnetic core preform 2.

[0114] J3) Prepare the soft magnetic material and the copper conductor 1

[0115] The soft magnetic material is a soft magnetic alloy powder doped with a binder. Among them, the soft magnetic alloy powder is a nanocrystalline powder, and the main component of the binder is polyimide.

[0116] The copper conductor 1 determined in step J1) is formed by wire cutting or integral stamping.

[0117] J4) Manufacture the magnetic core preform 2

[0118] Adjust the relative position between the lower punch and the middle die of the servo press die to form a preset height difference.

[0119] Uniformly fill the cavity surrounded by the middle die and the lower punch with the soft magnetic material.

[0120] First, use a machine pressure of 1.0 T (unit area pressure: 2.5 T / cm 2 ), press for 0.5 s, then adjust the pressure to 2.0 T (unit area pressure: 5.0 T / cm 2 ), hold the pressure for 2 s, and then increase the pressure to 3.5 T (unit area pressure: 8.7 T / cm 2 ), hold the pressure for 0.5 s. Form the magnetic core preform 2 determined in step J1).

[0121] J5) Implant the copper conductor 1

[0122] Along the pressing direction, implant the copper conductor 1 into the installation groove to form an inductor preform. Among them, the second component 12 is embedded in the transverse groove 21, the first component 11 is inserted into the first vertical groove 22, the third component 13 is inserted into the second vertical groove 23, and the part of the copper conductor 1 located in the installation groove is in contact with the groove wall of the installation groove.

[0123] J6) Hot pressing

[0124] Control the temperature of the die to 150 °C, use a machine pressure of 3.0 T (unit area pressure: 7.5 T / cm 2 ), hold the pressure for 20 s. Then adjust the die temperature to 200 °C and adjust the pressure to 4.5 T (unit area pressure: 11.2 T / cm 2) The holding pressure time is 100S. Demold to form the inductor body 3.

[0125] J7) After the inductor body 3 goes through processes such as chamfering, spraying, grinding, paint stripping, and electroplating, the finished inductor is obtained.

[0126] Comparative Example 1:

[0127] The difference between Comparative Example 1 and Example 1 is that in step S4) of Comparative Example 1, no pressure was applied during the pressurized preheating stage, and only the mold temperature was controlled at 150 °C and maintained at this temperature for 20S. Subsequently, the main pressure was applied, and the main pressure was 11.2T / cm 2 , and the holding pressure time was 120S.

[0128] Example 2:

[0129] The difference between Example 2 and Example 1 is that in step S4) of Example 2, after the main pressure stage, a slow release stage is further included, and the pressure in the slow release stage is 5.0T / cm 2 , the holding pressure time is 30S, and the mold temperature is 180 °C.

[0130] Example 3:

[0131] The difference between Example 3 and Example 1 is that in step S4) of Example 3, different hot pressing parameters from those in Example 1 are selected. In Example 3, during pressing, first control the mold temperature at 150 °C, and use a pressure of 10.0T / cm 2 , and hold the pressure for 20S. Then adjust the mold temperature to 200 °C and adjust the pressure to 15.0T / cm 2 , and the holding pressure time is 100S. Demold to form the inductor body 3.

[0132] Comparative Example 2:

[0133] The difference between Comparative Example 2 and Example 3 is that in step S4) of Comparative Example 2, no pressure was applied during the preheating stage, and only the mold temperature was controlled at 150 °C and maintained at this temperature for 20S. Subsequently, the main pressure was applied, and the main pressure was 15.0T / cm 2 , and the holding pressure time was 120S.

[0134] Example 4:

[0135] The difference between Example 4 and Example 3 is that in step S4) of Example 4, after the main pressure stage, a slow release stage is further included, and the pressure in the slow release stage is 7.5T / cm 2 , the holding pressure time is 30S, and the mold temperature is 180 °C.

[0136] Example 5:

[0137] Example 5 is different from Example 1 in that in step S2), a pressure of 3.7 T / cm 2 is applied for 0.5 s, then the pressure is adjusted to 7.5 T / cm 2 , the pressure is maintained for 2 s, and then the pressure is increased to 10.0 T / cm 2 , and the pressure is maintained for 0.5 s. The magnetic core preform 2 determined in step J1) is formed.

[0138] Comparative Example 3:

[0139] Comparative Example 3 is different from Example 1 in that in step S2), a single pressure of 5.0 T / cm 2 is applied for 2 s. The magnetic core preform 2 determined in step J1) is formed.

[0140] Comparative Example 4:

[0141] Comparative Example 4 is different from Example 5 in that in step S2), a single pressure of 7.5 T / cm 2 is applied for 2 s to form the magnetic core preform 2 determined in step J1).

[0142] During the production process of the inductor, the density and height dimensions of the magnetic core preforms 2 prepared in Examples 1 to 5 and Comparative Examples 1 to 4 were detected.

[0143] The density and inductance value of the inductor bodies 3 prepared in Examples 1 to 5 and Comparative Examples 1 to 4 were detected.

[0144] The density of the magnetic core preform 2 and the density of the inductor body 3 were both detected by the "Archimedes drainage method". The size of the magnetic core preform 2 was measured with a height gauge. The inductance value of the inductor body 3 was detected by impedance analysis. See Table 1 for the test results.

[0145] Table 1:

[0146]

[0147] Analysis of test results:

[0148] Comparing the inductor manufacturing methods of Example 1 and Comparative Example 1, the difference between Example 1 and Comparative Example 1 is that in the hot pressing process, pressure was applied in the preheating stage in Example 1, while in the preheating stage of the hot pressing process in Comparative Example 1, only the temperature of the mold was controlled and no pressure was applied.

[0149] Compare the density values and inductance values after hot pressing of Example 1 and Comparative Example 1. The inductance body produced in Example 1 has better density values and higher inductance values. This shows that applying pressure during the preheating stage is beneficial to improving the density of the inductance body, and thus enhancing the inductance value of the inductance body.

[0150] Compare the inductance manufacturing methods of Example 1 and Example 2. The difference between Example 2 and Example 1 is that after the main pressing stage, Example 2 also includes a slow release stage.

[0151] Compare the appearances of the inductance bodies produced in Example 1 and Example 2. Cracks are formed on the side of the inductance body in Example 1 after demolding; after demolding in Example 2, the surface of the inductance body is smooth and there is no abnormality.

[0152] Through the appearance comparison between Example 1 and Example 2, it can be shown that in the hot pressing process, adding a slow release stage after the main pressing stage helps to prevent the inductance body from shrinking and cracking, and makes the density, size, etc. of the product stable.

[0153] Compare the inductance manufacturing methods of Example 1 and Comparative Example 3. The difference between Example 1 and Comparative Example 3 is that when manufacturing the magnetic core preform through the cold pressing process, Example 1 uses gradient pressure. When manufacturing the magnetic core preform through the cold pressing process, Comparative Example 3 uses single pressure.

[0154] Compare the density values of the magnetic core preforms produced in Example 1 and Comparative Example 3. The density of the magnetic core preform produced in Example 1 is higher than that of the magnetic core preform produced in Comparative Example 3. This shows that in the cold pressing process, using gradient pressure helps to increase the density of the magnetic core preform, and thus helps to increase the inductance value of the inductance.

[0155] Compare the sizes of the magnetic core preforms produced in Example 1 and Comparative Example 3. The size of the magnetic core preform produced in Example 1 is closer to the designed size of the magnetic core preform. The size of the magnetic core preform produced in Comparative Example 3 is larger than the size of the magnetic core preform produced in Example 1. This shows that in the cold pressing process, after the main pressing, applying a final pressing with a greater pressure can reduce the expansion degree of the magnetic core preform after demolding and stabilize the size of the magnetic core preform.

[0156] Example 3 and Comparative Example 2 form a set of comparative examples, and the comparison results are similar to those of the comparative example formed by Example 1 and Comparative Example 1; Example 3 and Example 4 form a set of comparative examples, and the comparison results are similar to those of the comparative example formed by Example 1 and Example 2. Example 5 and Comparative Example 4 form a set of comparative examples, and the comparison results are similar to those of the comparative example formed by the Example and Comparative Example 3; details are not described here again.

[0157] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A manufacturing method of a magnetic core embedded with copper inductance, characterized in that, It includes the following steps: S1) Prepare soft magnetic materials and copper conductors The soft magnetic material is soft magnetic alloy powder doped with binder; The copper conductor includes a first component part, a second component part and a third component part connected in sequence. The first component part and the third component part are bent towards the same direction relative to the second component part. The included angle between the first component part and the second component part is α1, and the included angle between the third component part and the second component part is α2, where 90° ≤ α1 ≤ 180° and 90° ≤ α2 ≤ 180°; S2) Manufacture a magnetic core preform Press the soft magnetic material through a cold pressing process to form an integrated magnetic core preform; Along the pressing direction, the magnetic core preform includes a first surface and a second surface that are parallel to each other, and an installation groove is formed in the magnetic core preform; the installation groove includes a transverse groove, a first vertical groove and a second vertical groove. The transverse groove opens on the first surface and extends parallel to the first surface; the first vertical groove and the second vertical groove are connected to both ends of the transverse groove. The extending directions of the first vertical groove and the second vertical groove are perpendicular to the first surface and penetrate from the first surface to the second surface; S3) Implant the copper conductor Along the pressing direction, implant the copper conductor into the installation groove to form an inductor preform; wherein, the second component part is embedded in the transverse groove, the first component part is inserted into the first vertical groove, the third component part is inserted into the second vertical groove, and the part of the copper conductor located in the installation groove is in contact with the groove wall of the installation groove; S4) Adopt a hot pressing process to perform secondary pressing on the inductor preform formed in step S3) to make the copper conductor tightly combined with the magnetic core preform to form an inductor body. After subsequent process treatment, a finished inductor is obtained; the pressing direction in the hot pressing process is the same as the pressing direction in the cold pressing process.

2. The manufacturing method of the magnetic core copper-embedded inductor according to claim 1, characterized in that, In step S3), the surface of the second component part facing away from the bending direction of the first component part is flush with the first surface.

3. The manufacturing method of the magnetic core embedded with copper inductor according to claim 2, characterized in that, In step S3), the end of the first component part away from the first surface extends out of the first vertical groove, and the end of the third component part away from the first surface extends out of the second vertical groove.

4. The manufacturing method of the magnetic core embedded with copper inductor according to claim 1, characterized in that, In step S2), the cold pressing process uses gradient pressure and successively includes a pre-pressing stage, a main pressing stage, and a final pressing stage. The pressure per unit area in the pre-pressing stage is 2.5 - 3.7 T / cm² 2 , the pressure per unit area in the main pressing stage is 5.0 - 7.5 T / cm² 2 , and the pressure per unit area in the final pressing stage is 8.7 - 10.0 T / cm² 2 .

5. The manufacturing method of the magnetic core embedded with copper inductor according to claim 1, characterized in that In step S4), the hot pressing process adopts gradient pressure, including a pressurization and preheating stage and a main pressing stage; The pressurization and preheating stage is used to soften the binder in the soft magnetic material, and through the preliminary pressure, the soft magnetic material can better fill the mold and remove air; The pressure in the main pressing stage is greater than the preliminary pressure, and the temperature in the main pressing stage is greater than the temperature in the pressurization and preheating stage. It is used to further compress the soft magnetic alloy powder, promote the mechanical interlocking and plastic deformation between the soft magnetic alloy powders, and complete the dynamic recrystallization and dense combination of the soft magnetic alloy powder.

6. The manufacturing method of the magnetic core embedded with copper inductor according to claim 5, characterized in that, In step S4), a pressure relief stage is further included after the main pressing stage. The pressure in the pressure relief stage is less than the pressure in the main pressing stage, and the temperature in the pressure relief stage is less than the temperature in the main pressing stage. It is used to reduce the pressure and temperature before demolding and reduce the release of internal stress.

7. The manufacturing method of the magnetic core embedded with copper inductor according to claim 6, characterized in that, The pressure per unit area in the pressurizing and preheating stage is 7.5 - 10.0 T / cm 2 , and the pressure per unit area in the main pressing stage is 11.2 - 15.0 T / cm 2 , and the pressure per unit area in the slow release stage is 5.0 - 7.5 T / cm 2 .

8. The manufacturing method of the magnetic core copper-embedded inductor according to claim 1, wherein, The subsequent processes include primary spraying and secondary spraying on the inductor body; The material for the primary spraying is an insulating material, and the material for the secondary spraying is a conductive material.

9. The manufacturing method of the magnetic core copper-embedded inductor according to claim 8, characterized in that, After the secondary spraying, it further includes the steps of stripping a part of the sprayed coating at the corresponding position of the first surface to expose at least part of the copper conductor, and electroplating at the stripped part of the sprayed coating.

10. An inductor manufactured by the method for manufacturing a magnetic core embedded copper inductor according to any one of claims 1 to 9.

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