Design and forming method of integrally formed inductor and common mode inductor

Abstract

The invention relates to a method for designing and forming an integrally formed inductor and a common mode inductor, which mainly comprises the following steps of: selecting amorphous powder, alloy powder, carbonyl iron powder and the like as magnetic materials, mixing the magnetic materials with thermosetting epoxy resin, and pressing the materials into a diaphragm by using a double-roller calender; and cutting the diaphragm, coating the diaphragm outside the flat copper wire, and winding the flat copper wire into the inductance coil. And the wound coil is baked and cured at 150-180 DEG C, and then secondary pressing is performed to ensure that the magnetic material compactly wraps the electrode, so that the electrode is prevented from being exposed. By optimizing the material ratio and the pressing process, the magnetic shielding effect and the anti-jamming capability of the inductor are improved, the heat dissipation performance is improved, the coil short circuit risk is avoided, and the inductor is suitable for application scenes such as high-frequency power supplies and communication equipment. The method is simple in process, high in production efficiency, suitable for large-scale automatic production and capable of meeting the manufacturing requirements of inductor products of different specifications.

Description

Technical Field

[0001] The present invention relates to the technical field of inductor manufacturing, and in particular to a design and molding method of an integrally molded inductor and a common-mode inductor. Background Art

[0002] As an important component in electronic circuits, inductors are widely used in power conversion, filtering, oscillation, energy storage and other fields, especially in high-frequency switching power supplies, mobile phones, automotive electronics and communication equipment. With the continuous development of electronic products towards miniaturization, integration and high efficiency, the requirements for inductors are getting higher and higher. Not only are they required to have high inductance and high quality factor, but they are also required to have good heat dissipation and anti-interference capabilities. The one-piece molded inductor has gradually become an important direction for the development of inductor technology due to its unique design and process characteristics.

[0003] Traditional inductors are usually made of coils and magnetic cores separately, and then assembled. In this way, there is an air gap between the coil and the magnetic core, which will cause magnetic leakage and reduce the efficiency of the inductor. Especially in high-frequency applications, the magnetic leakage problem is more obvious. In addition, the coil of traditional inductors is prone to poor heat dissipation during the winding process due to uneven distance between turns, which affects the performance and service life of the inductor. In order to deal with these problems, one-piece molded inductor design solutions have gradually appeared on the market.

[0004] An integrated inductor is one that uses a one-step molding process to make a coil and magnetic material, so that the coil is completely embedded in the magnetic material, thereby reducing the air gap and improving the working efficiency of the inductor. In this design, the magnetic material and the coil are integrated, the magnetic shielding effect is significant, the leakage magnetic field is small, the electromagnetic interference to the external environment is small, and it has better thermal stability and mechanical strength. The application of integrated inductors is gradually becoming more widespread, especially in application scenarios that require high current and high frequency, such as power modules, DC-DC converters, LED driver power supplies, etc. However, despite the obvious advantages of integrated inductors, the current manufacturing process still faces many challenges.

[0005] At present, there are two main molding methods for the production of one-piece molded inductors: one is to use round copper wire as the coil, and the other is to use flat copper wire. In the molding process using round copper wire, the copper wire is first wound into a hollow coil and fixed on the lead frame, and then the welded coil is placed in the mold, filled with magnetic material, and finally formed by pressing. Although this process can achieve one-piece molding, the defects in its molding process are more significant. First, due to the irregular internal structure of the circular coil, the magnetic material is unevenly distributed during pressing, especially in the center area of ​​the coil, the density of the magnetic material is low, which in turn affects the overall performance of the inductor. Secondly, the surface of the round copper wire is easily damaged during the pressing process, which destroys its insulation layer and increases the risk of coil short circuit.

[0006] Another common process is to use flat copper wire to wind the coil, and then place it in a mold for pressing. This design can partially solve the problems in the round copper wire process, because the flat copper wire has a more regular structure, the magnetic material is relatively evenly distributed during pressing, and due to the flat shape of the flat copper wire, the coil is more compact after winding, and the heat dissipation performance is better than that of round copper wire. However, the flat copper wire process also has certain shortcomings. Since the edge of the flat copper wire is wider, it is easy to block the flow of magnetic materials, resulting in uneven filling of some electrode areas in the finished inductor, and the electrodes are exposed to the external environment, thereby reducing the magnetic shielding effect and insulation of the inductor.

[0007] In addition, as modern electronic devices develop towards high power density, miniaturization, and high frequency, the requirements for the size, performance, and heat dissipation of inductors are getting higher and higher. The existing one-piece molded inductor design can no longer meet higher-level technical requirements. In particular, in the design and manufacture of common-mode inductors, the coils are required to have higher symmetry, anti-interference ability, and better leakage inductance control. However, traditional process methods are difficult to effectively achieve the high performance requirements of common-mode inductors in small sizes.

[0008] In view of the above problems, the present invention proposes a new design and molding method of one-piece molded inductor and common-mode inductor, which further improves the overall performance of the inductor by introducing optimized material ratios, precise calendering process and secondary pressing technology. In the present invention, the magnetic material and the coil are closely combined through calendering and coating processes to ensure the uniformity and density of the material during the pressing process. At the same time, the flat copper wire winding process is adopted, combined with the improved mold design, to avoid the exposure of the electrode, greatly improving the shielding effect and reliability of the inductor. In addition, through the superposition and winding process of multi-layer diaphragms, the present invention also realizes the efficient design of common-mode inductors, meeting the demand for high performance of inductors in different application scenarios.

[0009] In short, as the requirements of electronic products for inductor performance continue to increase, traditional inductor design and manufacturing processes have gradually exposed their limitations. One-piece molded inductors have become the main direction of future inductor technology development due to their excellent magnetic shielding performance, small magnetic leakage and good heat dissipation capabilities. In view of the deficiencies in the prior art, the present invention provides an improved one-piece molded inductor and common mode inductor design and molding method, which has broad application prospects. Summary of the invention

[0010] The purpose of the present invention is to provide a design and molding method of an integrally molded inductor and a common mode inductor to address the deficiencies of the prior art, so as to solve the problems raised in the background technology.

[0011] To achieve the above object, the present invention provides the following technical solution: a design and molding method of an integrally molded inductor and a common mode inductor, comprising the following steps:

[0012] S1: Select amorphous powder, alloy powder, and carbonyl iron powder as magnetic materials;

[0013] S2: Mix the magnetic material in S1 with a thermosetting epoxy resin, wherein the content of the epoxy resin is 8.0%-15.0%;

[0014] S3: Use a double-roll calender to press the mixed material of S2 into a film with a thickness of 0.1-0.3 mm;

[0015] S4: Cut the film obtained in S3 and wrap it around the outside of the flat copper wire;

[0016] S5: The flat copper wire covered with the diaphragm obtained in S4 is wound into an inductor;

[0017] S6: The wound inductor is fixed between the clamping plates and baked at 150-180°C for curing;

[0018] S7: Perform secondary pressing on the formed inductor to obtain a state where the electrode is completely wrapped by the diaphragm.

[0019] As a preferred technical solution of the present invention, in the magnetic material, the D50 size range of amorphous powder or alloy powder is 10-15 μm, accounting for 20-40%; the D50 size range of carbonyl iron powder is 3-7 μm, accounting for 60-80%.

[0020] As a preferred technical solution of the present invention, in the process of mixing the magnetic material and the epoxy resin, anhydrous ethanol or acetone is used as a solvent.

[0021] As a preferred technical solution of the present invention, the twin-roll calender operates without heating, and the temperature of the material during the pressing process is controlled by a cooling water system to be kept at room temperature.

[0022] As a preferred technical solution of the present invention, 2-3 cm of length is reserved at both ends of the flat copper wire as electrodes, and during the winding process, the electrode portion is not covered by the magnetic material.

[0023] As a preferred technical solution of the present invention, the formed inductor is wound into a common-mode inductor by using two identical flat copper wires.

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

[0025] The present invention improves the compactness of magnetic materials and the overall performance of the inductor through processes such as double-roll calendering and secondary pressing. Compared with traditional inductors, the present invention is more uniform during material filling and pressing, significantly reduces air gaps, ensures the magnetic shielding effect of the inductor, reduces magnetic leakage, and improves the anti-interference ability of the inductor. In addition, the design of flat copper wire winding avoids the problems of insulation layer damage and coil short circuit in traditional processes, greatly improving the safety and reliability of the inductor.

[0026] By coating the inductor coil and stacking the multi-layer diaphragm, the present invention significantly improves the heat dissipation performance of the inductor and ensures stability in high-frequency and high-current applications. At the same time, the molding process of the present invention is flexible and diverse, and can adjust the material ratio and process parameters according to different application requirements, supporting the production of inductor products of various specifications without significantly changing the production line settings, thereby greatly reducing production costs and improving production efficiency.

[0027] Finally, the present invention is suitable for the production of common-mode inductors. It adopts a symmetrical winding process to improve the ability to resist common-mode interference. The overall structure of the inductor has stronger mechanical strength and can withstand vibrations and impacts in complex environments. It is suitable for high-demand application scenarios such as automotive electronics and industrial equipment, showing broad market prospects and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of an inductor wound with a flat copper wire covered with a diaphragm;

[0029] Figure 2 It is a schematic diagram of the structure of two identical flat copper wires wound into a common-mode inductor. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings and multiple embodiments.

[0032] Example 1: Fabrication of a single-layer integrally molded inductor

[0033] Material selection and proportion: amorphous powder, alloy powder and carbonyl iron powder are selected. The D50 size of amorphous powder is 12μm, accounting for 30%; the D50 size of alloy powder is 11μm, accounting for 20%; the D50 size of carbonyl iron powder is 5μm, accounting for 50%.

[0034] 10% thermosetting epoxy resin was used as a binder, and anhydrous ethanol was used as a solvent.

[0035] Material mixing: Mix the magnetic powder with epoxy resin, add an appropriate amount of anhydrous ethanol, and mix evenly in a blender for 30 minutes to ensure that each magnetic particle is evenly coated with epoxy resin.

[0036] Calendering: The mixture is pressed into a 0.2mm thick film using a double-roll calender without heating. During the calendering process, the roller temperature is controlled at 20-25°C and the temperature is kept stable by a water cooling system to prevent the material from generating excessive heat due to friction.

[0037] Coated rectangular copper wire: Figure 1 As shown, the membrane is cut into 1.5 mm wide strips and wrapped on 2 mm wide flat copper wires. 2.5 cm is reserved at both ends of the copper wire as electrodes.

[0038] Winding inductor: The flat copper wire coated with magnetic material is wound in a spiral manner to form an inductor coil. During the winding process, ensure that the turns of the coil are evenly spaced and the tension in the inductor is stable.

[0039] Initial curing: Fix the wound inductor coil in the mold and bake it at 160℃ for 40 minutes to initially cure the epoxy resin and keep the coil in shape.

[0040] Secondary pressing and molding: The solidified inductor is pressed for the second time, using a pressure of 10-20MPa to ensure the density of the magnetic material. This step ensures that the electrode is completely wrapped by the magnetic material, preventing the electrode from being exposed and improving the magnetic shielding performance of the inductor.

[0041] In the same way, two identical wires can be twisted together to form a common-mode inductor. Figure 2 .

[0042] Example 2: Fabrication of a multi-layer integrated inductor

[0043] Material selection: Carbonyl iron powder and amorphous powder are selected. The D50 size of carbonyl iron powder is 6μm, accounting for 70%; the D50 size of amorphous powder is 12μm, accounting for 30%.

[0044] Use 15% epoxy as the binder and acetone as the solvent, making sure the materials are thoroughly mixed.

[0045] Material mixing and calendering: The magnetic material and epoxy resin are uniformly mixed in a mixer, and the mixed material is pressed into a 0.3mm thick film using a double-roll calender. In order to prevent the magnetic material from agglomerating, the roller speed is controlled to 30rpm and the material temperature is maintained at 25℃.

[0046] Lamination process: Cut the diaphragm into 2mm width and wrap it around the 2.5mm wide flat copper wire. Use the lamination process to wrap 2-3 layers of diaphragm on the copper wire layer by layer, ensuring that there is no air gap between each layer and that the diaphragm fits tightly to the copper wire.

[0047] Winding and shaping: Figure 1 As shown, multiple layers of coated flat copper wire are wound into an inductor coil, keeping the distance between each turn accurate to prevent short circuits between layers.

[0048] The wound inductor coil is placed in a 150°C environment and baked for 60 minutes for preliminary curing.

[0049] Secondary pressing and molding: Place the initially solidified inductor into the mold for secondary pressing, applying a pressure of 15-25MPa to further improve the density of the inductor coil and ensure that each layer of diaphragm is evenly coated.

[0050] Finished product processing: After the second pressing, the inductor coil is taken out and cut to remove the excess parts to ensure that the surface of the inductor is flat and there is no exposed magnetic material on the electrode part.

[0051] In the same way, two identical wires can be twisted together to form a common-mode inductor. Figure 2 .

[0052] Example 3: Fabrication of common mode inductors

[0053] Material selection: Carbonyl iron powder is selected as the main magnetic material, with a D50 size of 4μm and a proportion of 100%. 8% epoxy resin mixed with acetone is used as a binder.

[0054] Material mixing and pressing: After the magnetic material and epoxy resin are evenly mixed, a double-roll calender is used to press them into a 0.15mm thick film. The roller speed is 40rpm to maintain a uniform pressing speed.

[0055] Copper wire coating: Figure 1As shown, two identical flat copper wires with a width of 1.8 mm are selected, and the diaphragm is cut and coated on the two copper wires respectively. During the coating process, ensure that the external magnetic material of each copper wire is evenly attached.

[0056] Winding common mode inductors: Use two flat copper wires coated with magnetic materials to wind common mode inductors. During the winding process, keep the two copper wires wound synchronously to ensure the symmetry of the winding and the consistency of the number of turns.

[0057] Place the wound common-mode inductor in the mold, clamp it, and bake it at 170°C for 50 minutes to solidify the epoxy resin and preliminarily shape the inductor.

[0058] Secondary pressing: The molded common mode inductor is subjected to secondary pressing, and a pressure of 20MPa is applied to ensure that the magnetic material is dense and free of bubbles.

[0059] Surface treatment and terminal treatment: Spray epoxy resin on the surface of the pressed common mode inductor to ensure that the external insulation layer of the inductor is intact.

[0060] The inductor electrodes are processed using laser cutting technology to ensure that there is no insulating material left on the electrode part, and a layer of tin is plated to ensure good electrical connection performance.

[0061] In the same way, two identical wires can be twisted together to form a common-mode inductor. Figure 2 .

[0062] Example 4: One-piece molded inductor with enhanced shielding effect

[0063] Material selection: alloy powder and carbonyl iron powder are used. The D50 size of the alloy powder is 15μm, accounting for 40%; the D50 size of the carbonyl iron powder is 5μm, accounting for 60%.

[0064] 12% thermosetting epoxy resin is used as the binder, and a small amount of antioxidant is added to enhance the durability of the inductor.

[0065] Material mixing and film production: After the magnetic material and epoxy resin are evenly mixed, they are pressed into 0.25mm film by a double-roll calender. During the calendering process, a low roller speed of 50rpm is used to maintain calendering uniformity.

[0066] Copper wire wrapping and layer winding: The diaphragm is cut into 3mm width and wrapped on a 3.5mm flat copper wire. In order to enhance the shielding effect, a four-layer layer winding process is adopted, with no air gap between each layer and ensuring a tight fit.

[0067] Winding and pressing: Figure 1 As shown, the coated flat copper wire is wound into an inductor and cured by baking at 170°C for 40 minutes.

[0068] After the initial solidification, secondary pressing is carried out, and a high pressure of 30MPa is applied to ensure that there is no gap between the copper wire and the magnetic material, thereby maximizing the magnetic shielding effect of the inductor.

[0069] Finished product processing and testing: After secondary pressing, the inductor is subjected to surface insulation treatment, sprayed with epoxy resin and baked for curing.

[0070] The leakage magnetic field and anti-interference performance tests are carried out using inductor testing equipment to ensure that the shielding effect of the inductor meets the design requirements.

[0071] In the same way, two identical wires can be twisted together to form a common-mode inductor. Figure 2 .

[0072] The above embodiments demonstrate the implementation of the present invention in various applications through different process parameters and material ratios. The manufacturing method of the integrated molded inductor and the common mode inductor of the present invention has the following advantages in practical applications:

[0073] Flexible process: According to different needs, the ratio of magnetic materials, the coating method of copper wire and the number of stacking layers can be flexibly adjusted to achieve inductor products with different performances.

[0074] Excellent inductance performance: Through double-roll calendering, secondary pressing and other processes, the density of magnetic materials and the high shielding performance of inductance are ensured.

[0075] Strong anti-interference ability: Multi-layer winding and precise process control ensure that the inductor has excellent anti-interference ability, suitable for high-frequency electronic equipment and power management modules.

[0076] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in the field. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A design and molding method of an integrated molded inductor and a common mode inductor, characterized in that: The following steps are involved: S1: Select amorphous powder, alloy powder, and carbonyl iron powder as magnetic materials; S2: Mix the magnetic material in S1 with a thermosetting epoxy resin, wherein the content of the epoxy resin is 8.0%-15.0%; S3: Use a double-roll calender to press the mixed material of S2 into a film with a thickness of 0.1-0.3 mm; S4: Cut the film obtained in S3 and wrap it around the outside of the flat copper wire; S5: The flat copper wire covered with the diaphragm obtained in S4 is wound into an inductor; S6: The wound inductor is fixed between the clamping plates and baked at 150-180°C for curing; S7: Perform secondary pressing on the formed inductor to obtain a state where the electrode is completely wrapped by the diaphragm.

2. The design and molding method of an integrated molded inductor and a common mode inductor according to claim 1, characterized in that: In the magnetic material, the D50 size range of amorphous powder or alloy powder is 10-15 μm, accounting for 20-40%; the D50 size range of carbonyl iron powder is 3-7 μm, accounting for 60-80%.

3. The design and molding method of an integrated molded inductor and a common mode inductor according to claim 1, characterized in that: In the process of mixing the magnetic material and the epoxy resin, anhydrous ethanol or acetone is used as a solvent.

4. The design and molding method of an integrated molded inductor and a common mode inductor according to claim 1, characterized in that: The twin-roll calender operates without heating, and the temperature of the material during the pressing process is controlled by a cooling water system to be kept at room temperature.

5. The design and molding method of an integrated molded inductor and a common mode inductor according to claim 1, characterized in that: A length of 2-3 cm is reserved at both ends of the flat copper wire as electrodes. During the winding process, the electrode portion is not covered by the magnetic material.

6. The design and molding method of an integrated molded inductor and a common mode inductor according to claim 1, characterized in that: The formed inductor is wound into a common mode inductor using two identical flat copper wires.

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