Co-fired TLVR coupled inductor, preparation method and application thereof

Abstract

The present application belongs to the technical field of automobile electronics, and relates to a co-firing molded TLVR coupled inductor and a preparation method and application thereof. The inductor prepared by the method has more excellent magnetic shielding performance and higher DC biasing capability, effectively solving the problems of increased leakage magnetic flux and magnetic interference caused by the adhesive air gap. In addition, by treating the surface of the copper sheet with a polysilazane-based spraying liquid, a dense ceramic insulation layer can be formed on the surface of the copper sheet after high-temperature sintering. The coating has good high-temperature stability and can withstand the high-temperature environment during the co-firing process, thereby avoiding the risk of interlayer short circuit caused by the failure of the insulation layer of the traditional enameled wire at high temperature.

Description

Technical Field

[0001] This invention belongs to the field of automotive electronic device technology, and relates to a co-fired molded TLVR coupled inductor, its preparation method and application. Background Technology

[0002] TLVR (Trans-Inductor Voltage Regulator) coupled inductor technology, as the mainstream circuit topology for addressing the challenges of "low voltage, high current, and fast response" power supply in high-performance computing, relies on a core mechanism: connecting specific tuned inductors in series with the secondary windings of each phase inductor to create a strong coupling path between the power phases. This unique structural design allows the controller's adjustment of the duty cycle of one phase to be rapidly transmitted to all phases via magnetic coupling when the load undergoes drastic transient changes. This drives the current in each phase to respond almost synchronously, significantly improving the system's slew rate and transient response bandwidth, effectively solving the lag problem of traditional multiphase power supplies when dealing with dynamic load fluctuations such as those from AI chips.

[0003] However, despite the significant advantages of the TLVR architecture in terms of electrical performance, its existing manufacturing process—the traditional route of using co-fired ferrite cores and pre-fabricated copper coils as an adhesive, followed by assembly with organic adhesives—is facing increasingly severe physical and engineering limitations. First, with the exponential growth in chip computing power demands, the operating frequency and current carrying capacity of power systems are constantly increasing. Traditional ferrite materials, limited by their physical properties, have insufficient saturation magnetic flux density (Bs) when facing extremely high current densities, easily leading to premature core saturation and loss of inductance characteristics, making it difficult to meet the stringent power density requirements of next-generation servers. Second, the adhesive bonding process itself has inherent structural defects that are difficult to eradicate. The non-magnetic air gaps formed by the adhesive layer in the magnetic circuit significantly increase magnetic reluctance, causing a sharp increase in leakage flux. Although ferrite has high intrinsic permeability, the air gap effect severely weakens the effective permeability of the core assembly, not only reducing energy transfer efficiency but also potentially causing severe electromagnetic interference to nearby sensitive magnetic components, affecting system stability.

[0004] In addition, the thermal matching problem in the manufacturing process is also not to be ignored. Ferrite cores must undergo a high-temperature environment during co-firing. This process is very likely to cause thermal damage or aging to the insulating coating on the surface of the adjacent coupling copper sheet, destroying the interlayer insulation performance and leading to fatal failure risks such as interlayer short circuits. This seriously restricts the application and yield improvement of TLVR inductors in high reliability scenarios.

[0005] Chinese patent application document (CN120636905A) discloses a high-temperature resistant insulated copper wire and its preparation method. However, the excessive addition of inorganic powder makes the surface insulation layer hard and brittle, which can easily cause damage to the insulation layer between copper wires during high-pressure forming. Summary of the Invention

[0006] To address the shortcomings of the prior art, this invention aims to provide a method for preparing a co-fired molded TLVR coupled inductor. This method aims to solve the technical problems of increased magnetic gap and severe magnetic leakage caused by adhesive bonding in traditional TLVR coupled inductors, as well as short circuits caused by damage to the insulating layer on the surface of adjacent copper sheets during the high-temperature co-firing process.

[0007] One objective of this invention can be achieved through the following technical solutions: A method for fabricating a co-fired molded TLVR coupled inductor, the method comprising the following steps: S1. Spray a coating liquid containing polysilazane onto the surface of a copper sheet, and then perform a curing process to obtain a copper sheet with a cured coating. S2. Repeat step S1 according to the preset curing coating thickness to obtain a cured copper sheet with the preset coating thickness; S3. After combining the solidified copper sheet and the pre-made magnetic core described in step S2, place them in a mold and hot-press them to obtain a molded inductor. S4. Then, the formed inductor is sintered to obtain a sintered inductor. S5. The sintered inductor is post-processed to obtain a co-fired molded TLVR coupled inductor.

[0008] In the above-mentioned method for preparing a co-fired molded TLVR coupled inductor, in step S1, the solid content of the spraying liquid containing polysilazane is 60% to 80%, including the following raw materials in parts by mass: 80-120 parts of polysilazane solution, 1-5 parts of nano-silica and 1-5 parts of glass microspheres.

[0009] The solid content of the polysilazane-containing spraying liquid used in this invention is strictly controlled within a high concentration range of 60% to 80% to ensure the density and mechanical strength of the film after formation. This spraying liquid mainly consists of a polysilazane solution as the film-forming matrix, supplemented with nano-silica and glass microspheres. The high concentration of polysilazane, after curing, forms an inorganic network structure with Si-N bonds as the main chain, endowing the insulating layer with excellent high-temperature resistance and mechanical toughness, enabling it to withstand the thermal stress in the subsequent co-firing process without cracking or peeling. The trace amounts of nano-silica, as high-dielectric-strength inorganic particles, uniformly dispersed in the polymer matrix, effectively improve the dielectric properties of the insulating layer, suppress local electric field concentration, and thus significantly enhance the overall insulation reliability. The addition of glass microspheres, without significantly increasing the dielectric constant, plays a role in adjusting the coating's thermal expansion coefficient, reducing internal stress, and helping to improve the coating's wear resistance and surface smoothness. This multi-component synergistic design not only gives the insulation layer excellent electrical insulation capabilities, but also ensures its long-term stability under high temperature, high humidity and high frequency operating environments, providing a key material basis for the co-fired manufacturing of TLVR inductors with high reliability and high integration.

[0010] Preferably, the average particle size of nano-silica is 10–100 nm.

[0011] Preferably, the average particle size of the glass microspheres is 5–15 μm.

[0012] In the above-mentioned method for preparing a co-fired molded TLVR coupled inductor, in step S1, the coating drying temperature is 170℃~190℃ and the time is 15min~25min.

[0013] In the above-mentioned method for preparing a co-fired molded TLVR coupled inductor, in step S2, the preset curing coating thickness is 0.1 to 0.4 mm, and the number of repetitions is 1 to 10.

[0014] Preferably, the preset curing coating thickness is 0.1 to 0.4 mm, and the number of repeated spraying and drying cycles is 5 to 8.

[0015] Traditional iron-based alloy powders often exhibit significant internal stress after being pressed at a preset temperature, hindering the development of their high magnetic permeability. This is a major drawback of alloy powders in TLVR coupled inductors. Therefore, high-temperature co-firing (high-temperature sintering) annealing is necessary to activate the high magnetic permeability of the alloy powder material. However, high-temperature sintering can damage the surface coating of adjacent copper conductors, leading to short circuits. This invention addresses this issue by applying a specially formulated polysilazane-containing coating liquid to the surface of a copper substrate to obtain a 0.1mm–0.4mm thick cured coating. After high-temperature sintering, an insulating ceramic layer is formed on the surface of the copper substrate, effectively solving the problem of short circuits caused by the high temperatures generated during co-firing damaging the surface coating of adjacent coupled copper conductors.

[0016] In the above-mentioned method for preparing a co-fired molded TLVR coupled inductor, in step S3, the magnetic core is prepared from soft magnetic alloy powder, wherein the soft magnetic alloy powder comprises the following raw materials in parts by mass: 90-110 parts of iron-nickel alloy powder, 1-3 parts of nano-silica powder, 0.5-2 parts of ferrite powder, 0.2-1.2 parts of water glass, and 0.1-1 parts of organosilicon.

[0017] The core of this step lies in replacing traditional ferrite powder with soft magnetic alloy powder having a higher saturation magnetic induction intensity (Bs), and combining this with a high-temperature sintering process to prepare a magnetic core with high effective permeability. By integrally pressing the insulated copper sheet and magnetic powder into a mold and then co-firing them, multiple prefabricated parts can be assembled without the need for adhesives, thus avoiding air gaps introduced by bonding. This structure significantly improves magnetic shielding and DC bias capability, and effectively suppresses problems such as increased leakage flux and decreased effective permeability caused by air gaps.

[0018] Preferably, the soft magnetic alloy powder needs to be processed by mixing with acetone, stirring, drying and granulation to obtain the soft magnetic alloy powder for the magnetic core.

[0019] In the above-mentioned method for preparing a co-fired molded TLVR coupled inductor, in step S3, the temperature during hot pressing is 180℃~220℃, the pressure is 600MPa~1000MPa, and the time is 50s~70s.

[0020] In the above-mentioned method for preparing a co-fired molded TLVR coupled inductor, in step S4, the sintering temperature is 500℃~550℃ and the time is 50min~70min; wherein the sintering atmosphere is a mixture of nitrogen and hydrogen, and the volume ratio of nitrogen to hydrogen is 1:(1~5).

[0021] In the above-mentioned method for preparing a co-fired molded TLVR coupled inductor, step S5 includes post-processing: grinding the sintered inductor to obtain exposed terminal areas, and then electroplating the terminal areas to form electrodes.

[0022] The present invention also provides a co-fired molded TLVR coupled inductor, which is prepared by the above method.

[0023] The present invention also provides an application of the above-mentioned co-fired molded TLVR coupled inductor in printed circuit boards and electronic components.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The preparation method provided by the present invention integrates the insulating cured copper sheet and the soft magnetic alloy core in a mold and achieves structural integration by co-firing process, thereby avoiding the assembly gaps introduced by the use of adhesives to bond multiple prefabricated parts in the traditional process.

[0025] 2. The inductor prepared by the method of this invention has superior magnetic shielding performance and higher DC bias capability, effectively solving the problems of increased leakage flux and magnetic interference caused by adhesive gaps. Furthermore, by treating the copper sheet surface with a polysiloxane-based spray coating, a dense ceramic insulating layer can be formed on the copper sheet surface after high-temperature sintering. This coating has good high-temperature stability and can withstand the high-temperature environment during co-firing, thus avoiding the risk of interlayer short circuits caused by the failure of traditional enameled wire insulation layers at high temperatures.

[0026] 3. This invention successfully overcomes the problems of decreased magnetic properties caused by the adhesive bonding process and insulation reliability caused by high-temperature co-firing in the traditional TLVR coupled inductor manufacturing process. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the preparation method of the co-fired molded TLVR coupled inductor in this invention. Figure 2 This is a structural breakdown diagram of the co-fired molded TLVR coupled inductor in this invention; pre-pressed magnetic core 10, first type copper sheet 20, second type copper sheet 30, pre-pressed magnetic core 40. Detailed Implementation

[0028] The invention will be more fully understood by reading the following detailed description. However, it should be understood that the detailed description disclosed below is merely exemplary of the invention, which can be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as the basis for the claims and as a representative basis for teaching those skilled in the art to employ the invention in different ways in any suitable detailed embodiment.

[0029] The present invention is further illustrated below by way of examples, but the invention is not limited to the scope of the examples described. All reagents and raw materials used in the following examples are commercially available, and test methods not specifically specified are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0030] according to Figure 1 The method for fabricating a co-fired molded TLVR coupled inductor, as shown, includes the following steps: S1. Dry and clean the copper sheet to obtain a clean copper sheet substrate; the cleaning is carried out by immersion in alcohol to remove surface grease and contaminants; S2. Copper sheet substrate is sprayed with a polysilazane-containing spraying liquid, and then heat-treated at 120-190℃ for 15 min to 25 min to obtain a first-coated copper sheet; wherein the polysilazane-containing spraying liquid has a solid content of 60% to 80% and contains the following raw materials in parts by mass: 80 to 120 parts of polysilazane solution, 1 to 5 parts of nano-silica with an average particle size of 10 to 100 nm, and 1 to 5 parts of glass microspheres with an average particle size of 5 to 15 μm; The polysilazane has a purity of not less than 99% and a molecular weight of 800-900. The spraying liquid needs to be filtered through a 110-130 mesh sieve to reduce impurities and ensure coating uniformity. S3. Repeat step S2 5-8 times according to the preset spray-dry coating thickness of 0.1-0.4mm to obtain a cured copper sheet with a coating thickness of 0.1-0.4mm; S4. After combining the two insulating and cured copper sheets described in step S3 with the pre-made magnetic core, place them in a mold and press them for a second preset time under a preset pressing temperature and pressure to obtain the molded inductor. The prefabricated magnetic core is formed by pressing soft magnetic alloy powder, with a pressure of 1500 MPa and a holding time of 5 seconds. The soft magnetic alloy powder is composed of the following components by weight: 90-110 parts iron-nickel alloy powder, 1-3 parts nano-silica powder, 0.5-2 parts ferrite powder, 0.2-1.2 parts water glass (as a binder), and 0.1-1 parts organosilicon. The magnetic powder is obtained by mixing, stirring, drying, and granulating the soft magnetic alloy powder with acetone. S5. In a nitrogen and hydrogen mixed atmosphere with a volume ratio of 1:(1~5), the molded inductor is sintered at a sintering temperature of 500℃~550℃ for 50min~70min to obtain a dense sintered inductor body. Figure 2 As shown; S6. Polish the surface of the sintered inductor to expose the terminal area, and then form electrodes on the terminals through an electroplating process to finally obtain the co-fired molded TLVR coupled inductor.

[0031] The present invention is further illustrated below with specific embodiments: Example 1: The first embodiment of the present invention provides a method for preparing a co-fired molded TLVR coupled inductor, the method comprising the following steps: S1. Dry and clean the copper sheet to obtain a clean copper sheet substrate; the cleaning is carried out by immersion in alcohol to remove surface grease and contaminants; S2. Copper sheet substrate is sprayed with a polysilazane-containing spraying liquid, and then heat-treated at 180°C for 20 min to obtain a single-coated copper sheet; wherein the polysilazane-containing spraying liquid has a solid content of 75% and contains the following raw materials in parts by mass: 95 parts of polysilazane solution, 2.5 parts of nano-silica with an average particle size of 50 nm and 2.5 parts of glass microspheres with an average particle size of 10 μm; The purity of the polysilazane is not less than 99%, and the spraying liquid must be filtered through a 120-mesh sieve to reduce impurities and ensure coating uniformity. It should be noted that excessive thickness of the polysilazane coating of this invention can easily lead to cracking, thereby affecting the inter-turn withstand voltage performance. Preferably, the coating thickness for a single curing cycle is controlled at 10–20 μm. After spraying, it needs to be surface-dried at room temperature for 40 minutes, and the coating thickness is gradually increased through 3–8 "spraying-surface-drying" cycles. After surface drying, it is then heated for further drying. The curing temperature can be adjusted within the range of 60–200°C. The higher the temperature, the shorter the time required for complete drying. The preferred drying temperature is 180℃, and the drying time is 20 min. The cured polysilazane exhibits certain hydrophobic and oleophobic properties; therefore, it is not advisable to spray continuously in the uncured state. Each subsequent spraying should be performed only after the previous one has cured. Before temperature curing, a 40-minute surface curing and drying process at room temperature is also included. S3. Repeat step S2 5 times according to the preset insulating coating thickness of 0.1mm-0.2mm to obtain a cured copper sheet with a coating thickness of 0.2mm; S4. After assembling the two solidified copper sheets with the prefabricated core, place them in the molding mold and press them at 220℃, 900MPa, and 60s to obtain the molded inductor. The prefabricated core is made by pressing soft magnetic alloy powder with a pressure of 1500 MPa and a holding time of 5 seconds. The soft magnetic alloy powder is composed of the following components by weight: 100 parts iron-nickel alloy powder, 2 parts nano-silica powder, 1 part ferrite powder, 0.7 parts water glass (as a binder), and 0.5 parts organosilicon. The magnetic powder is obtained by mixing, stirring, drying, and granulating the soft magnetic alloy powder with acetone. S5. In a nitrogen and hydrogen mixed atmosphere with a volume ratio of 1:3, the shaped inductor is sintered at 550℃ for 60 minutes to obtain a dense sintered inductor body. S6. Polish the surface of the sintered inductor to expose the terminal area, and then form electrodes on the terminals through an electroplating process to finally obtain the co-fired molded TLVR coupled inductor.

[0032] Example 2: The first embodiment of the present invention provides a method for preparing a co-fired molded TLVR coupled inductor, the method comprising the following steps: S1. Dry and clean the copper sheet to obtain a clean copper sheet substrate; the cleaning is carried out by immersion in alcohol to remove surface grease and contaminants; S2. Copper sheet substrate is sprayed with a polysilazane-containing spraying liquid, and then heat-treated at 180°C for 20 min to obtain a single-coated copper sheet; wherein the polysilazane-containing spraying liquid has a solid content of 75% and contains the following raw materials in parts by mass: 95 parts of polysilazane solution, 2.5 parts of nano-silica with an average particle size of 50 nm and 2.5 parts of glass microspheres with an average particle size of 10 μm; The purity of the polysilazane is not less than 99%, and the spraying liquid must be filtered through a 120-mesh sieve to reduce impurities and ensure coating uniformity. It should be noted that excessive thickness of the polysilazane coating of this invention can easily lead to cracking, thereby affecting the inter-turn withstand voltage performance. Preferably, the coating thickness for a single curing cycle is controlled at 10-20 μm. After spraying, it needs to be surface-dried at room temperature for 30-45 minutes, and the coating thickness is gradually increased through 3-8 "spray-surface-dry" cycles. After surface drying, curing is performed at a higher temperature, which can be adjusted within the range of 60-200℃. The higher the temperature, the shorter the time required for complete curing. The preferred drying temperature is 180℃, and the drying time is 20 min. The cured polysilazane exhibits certain hydrophobic and oleophobic properties; therefore, it is not advisable to spray continuously in the uncured state. Each subsequent spraying should be performed only after the previous one has cured. Before temperature curing, a 40-minute surface curing and drying process at room temperature is also included. S3. Repeat step S2 10 times according to the preset curing coating thickness of 1 mm-5 mm to obtain an insulating copper sheet with a coating thickness of about 4 mm. S4. After assembling the two solidified copper sheets with the prefabricated core, place them in the molding mold and press them at 220℃, 900MPa, and 60s to obtain the molded inductor. The prefabricated core is made by filling and pressing soft magnetic alloy powder, with a pressure of 1500 MPa and a holding time of 5 seconds. The soft magnetic alloy powder is composed of the following by weight: 110 parts iron-nickel alloy powder, 3 parts nano silica powder, 2 parts ferrite powder, 1.2 parts water glass (as a binder), and 1.0 part organosilicon. The magnetic powder is obtained by mixing, stirring, drying, and granulating the soft magnetic alloy powder with acetone. S5. In a nitrogen and hydrogen mixed atmosphere with a volume ratio of 1:3, the shaped inductor is sintered at 550℃ for 60 minutes to obtain a dense sintered inductor body. S6. Polish the surface of the sintered inductor to expose the terminal area, and then form electrodes on the terminals through an electroplating process to finally obtain the co-fired molded TLVR coupled inductor.

[0033] Example 3: The first embodiment of the present invention provides a method for preparing a co-fired molded TLVR coupled inductor, the method comprising the following steps: S1. Dry and clean the copper sheet to obtain a clean copper sheet substrate; the cleaning is carried out by immersion in alcohol to remove surface grease and contaminants; S2. Copper sheet substrate is sprayed with a polysilazane-containing spraying liquid, and then heat-treated at 180°C for 20 min to obtain a single-coated copper sheet; wherein the polysilazane-containing spraying liquid has a solid content of 75% and contains the following raw materials in parts by mass: 95 parts of polysilazane solution, 2.5 parts of nano-silica with an average particle size of 50 nm and 2.5 parts of glass microspheres with an average particle size of 10 μm; The purity of the polysilazane is not less than 99%, and the spraying liquid must be filtered through a 120-mesh sieve to reduce impurities and ensure coating uniformity. It should be noted that excessive thickness of the polysilazane coating of this invention can easily lead to cracking, thereby affecting the inter-turn withstand voltage performance. Preferably, the coating thickness for a single curing cycle is controlled at 10-20 μm. After spraying, it needs to be surface-dried at room temperature for 30-45 minutes, and the coating thickness is gradually increased through two "spray-surface-dry" cycles. After surface drying, curing is performed at a higher temperature, which can be adjusted within the range of 60-200℃. The higher the temperature, the shorter the time required for complete curing. The preferred curing temperature is 180℃, and the curing time is 20 min. The cured polysilazane exhibits certain hydrophobic and oleophobic properties; therefore, it is not advisable to continuously spray it in the uncured state. Each subsequent spraying should only be performed after the previous one has cured. Before the temperature curing, a 40-minute surface curing and drying process at room temperature is also included. S3. Repeat step S2 twice according to the preset curing coating thickness of 0.01mm-0.05mm to obtain an insulating copper sheet with a coating thickness of about 0.02mm. S4. After assembling the two solidified copper sheets with the prefabricated core, place them in the molding mold and press them at 180°C, 900MPa, and 70 s to obtain the molded inductor. The prefabricated core is made by pressing soft magnetic alloy powder, with a pressure of 1500 MPa and a holding time of 5 seconds. The soft magnetic alloy powder is composed of the following by weight: 90 parts iron-nickel alloy powder, 1 part nano silica powder, 0.5 parts ferrite powder, 0.2 parts water glass (as a binder), and 0.1 parts organosilicon. The magnetic powder is obtained by mixing, stirring, drying, and granulating the soft magnetic alloy powder with acetone. S5. In a nitrogen and hydrogen mixed atmosphere with a volume ratio of 1:3, the shaped inductor is sintered at 550℃ for 60 minutes to obtain a dense sintered inductor body. S6. Polish the surface of the sintered inductor to expose the terminal area, and then form electrodes on the terminals through an electroplating process to finally obtain the co-fired molded TLVR coupled inductor.

[0034] Example 4: The only difference from Example 1 is that the hot pressing pressure in step S4 is 2000 MPa.

[0035] Example 5: The only difference from Example 1 is that the hot pressing pressure in step S4 is 300 MPa.

[0036] Example 6: The only difference from Example 1 is that the spray liquid containing polysilazane is only polysilazane.

[0037] Example 7: The only difference from Example 1 is that the coating liquid is replaced with the following paint; Matrix resin: 25 parts polysilazane; Inorganic filler: 15 parts of nano-sized alumina (particle size 10-20nm), 10 parts of nano-sized titanium dioxide (particle size 5-10nm), and 5 parts of aluminum silicate (fiber length ≤5μm). Functional fillers: 8 parts of color filler (iron oxide red, particle size ≤1μm) and 8 parts of high temperature resistant filler (boron nitride: mica powder = 5:5); Auxiliary components: 15 parts organic modified silicone resin, 7 parts curing agent (polyamide), 8 parts diluent (xylene, analytical grade), 7 parts binder (waterborne polyurethane dispersion, solid content 30%), and 6 parts additives (phosphate ester stabilizer, antioxidant).

[0038] Example 8: The only difference from Example 1 is that, in step S2, the spray liquid containing polysilazane does not contain glass microspheres.

[0039] Example 9: The only difference from Example 1 is that, in step S2, the amount of glass microspheres added to the polysilazane-containing spray liquid is 15 parts.

[0040] Example 10: The only difference from Example 1 is that, in step S2, the amount of nano-silica added to the spraying liquid containing polysilazane is 15 parts.

[0041] Comparative Example 1: The difference from Example 1 is that the magnetic powder core used in this comparative example is ferrite powder pressed and sintered, and its forming process adopts the traditional split assembly method, that is: firstly, ferrite co-fired pre-fabricated magnetic core and pre-fabricated copper sheet coil are prepared separately, and the two are combined into a bond; then, the two such bonded bodies are assembled and combined with adhesive to finally form a TLVR coupled inductor structure.

[0042] Comparative Example 2: The only difference from Example 1 is that step S3, which involves repeated spraying of insulation, was not performed.

[0043] Comparative Example 3: The only difference from Example 1 is that the copper sheet was not subjected to the insulation spraying treatment in steps S2 and S3.

[0044] Various performance tests were conducted on the co-fired molded TLVR coupled inductors prepared in the above embodiments and comparative examples. It should be noted that the temperature rise current test method is to apply current to the integrally molded inductor at room temperature. The current when the temperature reaches 65°C is the temperature rise current. DCR is the DC resistance. The measured object is the DC resistance between terminals 1-2 and terminals 3-4.

[0045] Table 1: Performance test results of co-fired molded TLVR coupled inductors prepared under different embodiments and comparative examples In summary, the inductor prepared by the method of this invention exhibits superior magnetic shielding performance and higher DC bias capability, effectively solving the problems of increased leakage flux and magnetic interference caused by adhesive gaps. Furthermore, by treating the copper sheet surface with a polysiloxane-based spray coating and then sintering at high temperature, a dense ceramic insulating layer can be formed on the copper sheet surface. This coating possesses good high-temperature stability and can withstand the high-temperature environment during co-firing, thereby avoiding the risk of interlayer short circuits caused by the failure of traditional enameled wire insulation layers at high temperatures.

[0046] The embodiments herein cover any points not exhaustively within the scope of the technical claims of this invention, as well as new technical solutions formed by equivalent substitutions of one or more technical features in the embodiments. These are all within the scope of the claims of this invention. Furthermore, in all listed or unlisted embodiments of this invention, each parameter in the same embodiment merely represents an instance (i.e., a feasible solution) of its technical solution, and there is no strict coordination or limitation relationship between the parameters. The parameters can be substituted for each other without violating axioms and the claims of this invention, unless otherwise stated.

[0047] The technical means disclosed in this invention are not limited to those described above, but also include technical solutions composed of any combination of the above technical features. The above descriptions are specific embodiments of this invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

[0048] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for preparing a co-fired molded TLVR coupled inductor, characterized in that, The method includes the following steps: S1. Spray a coating liquid containing polysilazane onto the surface of a copper sheet, and then perform a curing process to obtain a copper sheet with a cured coating. S2. Repeat step S1 according to the preset curing coating thickness to obtain a cured copper sheet with the preset coating thickness; S3. After combining the solidified copper sheet and the pre-made magnetic core described in step S2, place them in a mold and hot-press them to obtain a molded inductor. S4. Then, the formed inductor is sintered to obtain a sintered inductor. S5. The sintered inductor is post-processed to obtain a co-fired molded TLVR coupled inductor.

2. The method for preparing a co-fired molded TLVR coupled inductor according to claim 1, characterized in that, In step S1, the solid content of the spraying liquid containing polysilazane is 60% to 80%, and it includes the following raw materials in parts by mass: 80 to 120 parts of polysilazane solution, 1 to 5 parts of nano-silica, and 1 to 5 parts of glass microspheres.

3. The method for preparing a co-fired molded TLVR coupled inductor according to claim 1, characterized in that, In step S1, the curing temperature is 170℃~190℃ and the time is 15min~25min.

4. The method for preparing a co-fired molded TLVR coupled inductor according to claim 1, characterized in that, In step S2, the preset curing coating thickness is 0.1 to 0.4 mm, and the number of repetitions is 1 to 10.

5. The method for preparing a co-fired molded TLVR coupled inductor according to claim 1, characterized in that, In step S3, the magnetic core is prepared from soft magnetic alloy powder, wherein the soft magnetic alloy powder comprises the following raw materials in parts by mass: 90-110 parts of iron-nickel alloy powder, 1-3 parts of nano-silica powder, 0.5-2 parts of ferrite powder, 0.2-1.2 parts of water glass, and 0.1-1 parts of organosilicon.

6. The method for preparing a co-fired molded TLVR coupled inductor according to claim 1, characterized in that, In step S3, the temperature during hot pressing is 180℃~220℃, the pressure is 600MPa~1000MPa, and the time is 50s~70s.

7. The method for preparing a co-fired molded TLVR coupled inductor according to claim 1, characterized in that, In step S4, the sintering temperature is 500℃~550℃ and the time is 50min~70min; The sintering atmosphere is a mixture of nitrogen and hydrogen, with a volume ratio of nitrogen to hydrogen of 1:(1-5).

8. The method for preparing a co-fired molded TLVR coupled inductor according to claim 1, characterized in that, In step S5, the post-processing includes: polishing the sintered inductor to obtain exposed terminal areas, and then electroplating the terminal areas to form electrodes.

9. A co-fired molded TLVR coupled inductor, characterized in that, The co-fired molded TLVR coupled inductor is prepared by the method described in any one of claims 1 to 8.

10. The application of the co-fired molded TLVR coupled inductor as described in claim 9 in printed circuit boards and electronic components.

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