Power inductor and manufacturing method thereof

Abstract

The power inductor comprises a magnet and an inner electrode located in the magnet, the magnet comprises magnet particles, oxidation films are formed on the surfaces of the magnet particles, the magnet comprises a first area and a second area, the first area is closer to the inner electrode than the second area, and the inner electrode is located between the first area and the second area. The thickness of the oxide film of the magnet particles in the first area is larger than that of the oxide film of the magnet particles in the second area, so that the first area has higher insulation performance than the second area. The power inductor has better insulation performance in a key area close to the electrodes, meanwhile, the overall electrical performance of the inductor is kept, and the requirement of modern electronic equipment for the high-voltage-resistance power inductor is met.

Description

Technical Field

[0001] The invention relates to electronic components, and in particular to a power inductor and a manufacturing method thereof. Background Art

[0002] The voltage resistance of power inductors is directly related to their safe working performance under rated voltage or transient overvoltage conditions such as switching operation and arc generation, and is an important indicator for measuring their insulation performance. With the rapid development of electronic equipment towards miniaturization, integration and high performance, more stringent requirements are placed on the voltage resistance of power inductors. However, power inductors produced by traditional lamination processes have limitations, especially in terms of insulation performance and voltage resistance, which makes it difficult to meet the growing application needs. Traditional power inductor products often show poor insulation performance and low voltage resistance when facing high voltage shocks, which not only limits their application in high-performance electronic equipment, but also poses a challenge to the reliability and safety of the equipment.

[0003] It should be noted that the information disclosed in the above background technology section is only used for understanding the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0004] The main purpose of the present invention is to overcome the defects existing in the above-mentioned background technology and provide a power inductor and a manufacturing method thereof.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A power inductor includes a magnet and an inner electrode located inside the magnet, wherein the magnet contains magnet particles, and an oxide film is formed on the surface of the magnet particles, wherein the magnet includes a first region and a second region, the first region is closer to the inner electrode than the second region, and the oxide film thickness of the magnet particles in the first region is greater than the oxide film thickness of the magnet particles in the second region, so that the first region has higher insulation performance than the second region.

[0007] Further:

[0008] The inner electrode includes multiple layers of coils, and the first region includes a magnet portion between different layers of coils.

[0009] The first region includes a magnet portion close to an upper surface of the uppermost coil and a magnet portion close to a lower surface of the lowermost coil.

[0010] The inner electrode includes a multi-layer coil, and the first region includes a magnet portion located inside the same plane as the coil and a magnet portion located outside the same plane as the coil.

[0011] The magnetic particles are iron-silicon-chromium alloy particles or iron-silicon-aluminum alloy particles, and the oxide film is a dense continuous layer composed of oxides of iron, silicon, and chromium or oxides of iron, silicon, and aluminum.

[0012] The thickness of the oxide film of the magnetic particles in the first region is 1.2 times or more the thickness of the oxide film of the magnetic particles in the second region.

[0013] The first region is within a range of 1.5*C around the inner electrode, where C is the interlayer film thickness.

[0014] A method for manufacturing a power inductor, comprising:

[0015] S1: fine powder magnet particles are used to prepare fine powder slurry, and coarse powder magnet particles are used to prepare coarse powder slurry;

[0016] S2: Use fine powder slurry to cast on the base film to form an internal electro-generated tape, and use coarse powder slurry to cast on the base film to form a substrate tape;

[0017] S3: Opening holes in the inner electrogenic belt and printing electrode patterns;

[0018] S4: Printing fine powder slurry on the area of ​​the inner electrogenic tape where the electrode pattern is not printed;

[0019] S5: According to the set lamination scheme, the multi-layer inner electrical tape and the substrate tape are aligned and laminated together;

[0020] S6: ultra-high isostatic pressing of the laminated product;

[0021] S7: Sintering the product after ultra-high isostatic pressing, wherein the thickness of the oxide film of the magnet particles in the first region formed by the fine powder slurry is greater than the thickness of the oxide film of the magnet particles in the second region formed by the coarse powder magnet.

[0022] Further:

[0023] In step S1, fine powder magnetic particles with a first porosity are prepared into a fine powder casting slurry, and fine powder magnetic particles with a second porosity are prepared into a fine powder filling slurry, wherein the first porosity is smaller than the second porosity; in step S2, the fine powder casting slurry is cast on a base film to form an inner electro-generated band; in step S4, the fine powder filling slurry is printed on an area of ​​the inner electro-generated band where an electrode pattern is not printed.

[0024] In step S3, a high-temperature oxygen-releasing substance source is added to the electrode slurry used for printing the electrode pattern.

[0025] The high temperature oxygen-releasing substance source is silver oxide.

[0026] The magnetic particles are iron-silicon-chromium alloy particles or iron-silicon-aluminum alloy particles.

[0027] The present invention has the following beneficial effects:

[0028] The present invention provides a power inductor and a method for making the same, which significantly improves the voltage resistance of the inductor and meets the strict requirements of modern electronic equipment for high-performance electronic components. The present invention can improve the insulation performance at different positions in a targeted manner without changing the electrical performance of the inductor, thereby enhancing the overall voltage resistance of the inductor. By forming a relatively thicker oxide film on the surface of the magnet particles in the first region close to the inner electrode, this design increases the insulation performance of the magnet region close to the inner electrode without affecting the electrical performance, and effectively prevents electrical breakdown under high voltage conditions, especially between layers and at the end. On the other hand, by improving the lamination manufacturing process of the power inductor and controlling the oxide film thickness of the particles at different positions of the product, the insulation performance of the key positions of the product can be improved in a targeted manner without changing the electrical performance of the product, thereby improving the voltage resistance of the product.

[0029] Furthermore, the present invention uses fine powder with lower porosity as the internal electrical band material, which increases the surface area and thickness of the oxide film of the interlayer particles. At the same time, by using fine powder with higher porosity as the internal electrical filling material, a wider entry channel is provided for air, which promotes the oxidation of the particles and increases the thickness of the oxide film on the particle surface. This not only improves the insulation capacity between the particles, but also enhances the insulation performance inside the particles.

[0030] Furthermore, high-temperature oxygen-releasing substances such as silver oxide are added to the electrode slurry. These substances release oxygen during the sintering process, further increasing the degree of oxidation of the particles near the inner electrode, especially the particles between layers and at the end positions, thereby increasing the thickness of the oxide film at these key positions and significantly improving the insulation capacity.

[0031] In summary, the power inductor of the present invention achieves improved insulation performance at key positions while ensuring stable electrical performance, thereby demonstrating excellent voltage resistance in modern electronic devices.

[0032] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the cross-sectional structure of a power inductor according to an embodiment of the present invention.

[0034] Figure 2 FIG. 1 is a top view of the relationship between the electrode position and the magnet part of an embodiment of the present invention.

[0035] Figure 3 This is an electron microscope test diagram of the oxide film thickness of an embodiment of the present invention.

[0036] In the figure, 1 is the substrate position, 2 is the interlayer position, 3 is the end position, 4 is the inner electrode, 5 is the magnet core column position (the magnet part surrounded by the coil), 6 is the magnet part position within the dotted line close to the electrode, 7 is the magnet part position outside the dotted line far from the electrode; 8 is the circular pit formed by removing the internal powder particles before the oxide film thickness test, 9 is the oxide film remaining after the powder particles fall off after the thickness test before treatment, and 10 is the remaining components. DETAILED DESCRIPTION

[0037] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention.

[0038] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, connection can be used for fixing as well as for coupling or communication.

[0039] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0041] Through in-depth research and analysis of power inductors with withstand voltage failure, the inventors found that the main reason for their failure was poor insulation between layers and at the end positions. Based on this, the product design and stacking process improvement of the present invention were proposed to specifically increase the oxide film thickness of the particles inside the magnet near the electrode position of the product, improve the insulation performance of the product near the electrode position, and at the same time, the degree of oxidation far away from the electrode position can remain unchanged, thereby achieving the purpose of improving the product's withstand voltage capability without reducing the product's electrical performance.

[0042] See also Figures 1 to 3, an embodiment of the present invention provides a power inductor, comprising a magnet and an inner electrode 4 located inside the magnet, the magnet comprising magnet particles, an oxide film formed on the surface of the magnet particles, wherein the magnet comprises a first region and a second region, the first region (see the magnet portion position 6 within the dotted line) is closer to the inner electrode 4 than the second region (see the magnet portion position 7 outside the dotted line), the oxide film thickness of the magnet particles in the first region is greater than the oxide film thickness of the magnet particles in the second region, so that the first region has higher insulation performance than the second region. By selectively increasing the oxide film thickness on the surface of the magnet particles in the first region relatively close to the inner electrode 4, the power inductor of the present invention can achieve a significant improvement in insulation performance while maintaining electrical performance, effectively enhance the voltage resistance of the inductor, and improve the reliability and durability of the inductor.

[0043] like Figure 1 As shown, in some embodiments, the inner electrode 4 includes multiple layers of coils, and the first region includes a magnet portion between different layers of coils (i.e., interlayer position 2). The first region may include a magnet portion close to the upper surface of the uppermost layer of coils and a magnet portion close to the lower surface of the lowermost layer of coils.

[0044] In some embodiments, the inner electrode 4 includes a multi-layer coil, and the first region includes a magnet portion located inside the same plane as the coil and a magnet portion located outside the same plane as the coil (ie, the end position 3).

[0045] In some embodiments, the magnetic particles are iron-silicon-chromium alloy particles or iron-silicon-aluminum alloy particles, and the oxide film is a dense continuous layer composed of oxides of iron, silicon, and chromium or oxides of iron, silicon, and aluminum.

[0046] In some embodiments, the thickness of the oxide film of the magnetic particles in the first region is more than 1.2 times the thickness of the oxide film of the magnetic particles in the second region.

[0047] In some embodiments, the first region is within a range of 1.5*C around the inner electrode 4, where C is the interlayer film thickness.

[0048] The embodiment of the present invention further provides a method for manufacturing a power inductor, comprising the following steps:

[0049] Step S1: preparing fine powder slurry with fine powder magnetic particles and preparing coarse powder slurry with coarse powder magnetic particles; the magnetic particles may be iron-silicon-chromium alloy or iron-silicon-aluminum alloy particles;

[0050] Step S2: using fine powder slurry to cast on the base film to form an internal electro-generated tape, and using coarse powder slurry to cast on the base film to form a substrate tape;

[0051] Step S3: drilling holes in the inner electrogenerated tape (for the conduction of electrodes between different layers) and printing electrode patterns;

[0052] Step S4: printing fine powder slurry on the area of ​​the inner electrogenic tape where the electrode pattern is not printed;

[0053] Step S5: According to the set lamination scheme, the multi-layer inner electrical tape and the substrate tape are aligned and laminated together;

[0054] Step S6: performing ultra-high isostatic pressing on the laminated product;

[0055] Step S7: sintering the product after ultra-high isostatic pressing, wherein the thickness of the oxide film of the magnet particles in the first region formed by the fine powder slurry is greater than the thickness of the oxide film of the magnet particles in the second region formed by the coarse powder magnet.

[0056] The inner electro-generated tape can form a magnetic part between different layers of coils, i.e., an interlayer part. The inner electro-generated tape can also form a magnetic part close to the upper surface of the uppermost coil and a magnetic part close to the lower surface of the lowermost coil. The fine powder slurry printed on the area of ​​the inner electro-generated tape where the electrode pattern is not printed can form a magnetic part located on the inner side of the same plane as the coil and a magnetic part (end part) located on the outer periphery of the same plane as the coil.

[0057] The present invention improves the lamination manufacturing process of the power inductor, controls the oxide film thickness of the magnetic particles at different positions of the product, and specifically improves the insulation performance of key positions of the product (especially between layers and ends) without changing the electrical performance of the product, thereby significantly improving the voltage resistance of the power inductor.

[0058] In some embodiments, in step S1, fine powder magnetic particles of a first porosity are used to prepare a fine powder casting slurry, and fine powder magnetic particles of a second porosity are used to prepare a fine powder filling slurry, wherein the first porosity is less than the second porosity; in step S2, the fine powder casting slurry is cast on the base film to form an inner electrogenic belt, and in step S4, the fine powder filling slurry is printed on the area of ​​the inner electrogenic belt where the electrode pattern is not printed (see Figure 1 ). By using fine powder with lower porosity as the inner electrical band material, the surface area and thickness of the oxide film of the interlayer particles are increased. At the same time, by using fine powder with higher porosity as the inner electrical filling material, a wider entry channel is provided for air, which promotes the oxidation of particles and increases the thickness of the oxide film on the particle surface. This not only improves the insulation capacity between particles, but also enhances the insulation performance inside the particles.

[0059] In some embodiments, in step S3, the electrode slurry used for printing the electrode pattern is added with a high-temperature oxygen-releasing substance source. The high-temperature oxygen-releasing substance source may be silver oxide. The high-temperature oxygen-releasing substance in the electrode slurry releases oxygen during the sintering process, further increasing the degree of oxidation of particles near the inner electrode, especially increasing the oxide film thickness of the magnetic particles at the interlayer and end positions, thereby improving the insulation performance and withstand voltage capability of the power inductor.

[0060] The specific embodiments of the present invention are further described below.

[0061] Embodiment 1

[0062] The present embodiment provides a manufacturing method for improving the voltage resistance capability of a power inductor. By improving the lamination process, the oxidation degree of particles at different positions inside the product is controlled, that is, the thickness of the oxide film of particles at different positions is controlled, so as to improve the insulation performance of positions prone to voltage shock short circuits, thereby improving the voltage resistance capability of the product.

[0063] See also Figure 1 and Figure 2 , a method for improving the voltage resistance of a power inductor, the method is as follows:

[0064] Step 1: Use Fe-Si-Cr alloy fine powder with low porosity to prepare fine powder casting slurry to increase the surface area of ​​interlayer particles and the area of ​​oxide film of particles at the interlayer position, and at the same time reduce the risk of electrode virtual connection and short circuit caused by silver migration;

[0065] Step 2: Use Fe-Si-Cr alloy fine powder with high porosity to prepare fine powder filling slurry, form a wider oxygen entry channel at the end position, and improve the oxidation degree of particles between layers and at the end position;

[0066] Step 3: preparing a coarse powder casting slurry with the coarse iron-silicon-chromium alloy powder;

[0067] Step 4: Use low-porosity fine powder casting slurry to cast on the PET film to form an internal electrical tape, and use coarse powder casting slurry to cast on the PET film to form a substrate tape;

[0068] Step 5: Prepare electrode slurry and add a certain proportion of high-temperature oxygen-releasing substances such as silver oxide to serve as an additional oxygen source for the oxide film formed by particles near the inner electrode during the sintering process;

[0069] Step 6: Drill holes in the inner electrogenic belt and print electrode patterns;

[0070] Step 7: Printing a high-porosity fine powder filling slurry on the area of ​​the inner electrogenic tape where the electrode pattern is not printed;

[0071] Step 8: According to the set lamination scheme, the multi-layer inner electrical tape and the substrate tape are aligned and laminated together;

[0072] Step nine: subjecting the laminated products to ultra-high isostatic pressing;

[0073] Step 10: Sintering the product after ultra-high isostatic pressing.

[0074] See also Figure 1 , the magnet portion position 6 within the dotted line is closer to the inner electrode 4 than the magnet portion position 7 outside the dotted line. Figure 2 The magnet area surrounded by two dotted lines is close to the inner electrode, while the magnet part beyond the two dotted lines is far away from the inner electrode. Figure 3 The pre-treatment process of the oxide film thickness test is further demonstrated, including the circular pit 8 formed after removing the internal powder particles, and the oxide film 9 remaining after the powder particles fall off after the pre-treatment of the thickness test, and the remaining part is marked as 10. While keeping the thickness of the oxide film far away from the electrode position unchanged, this embodiment significantly improves the insulation performance of this area by increasing the area and thickness of the oxide film close to the electrode position. This design strategy ensures that the product's withstand voltage capability is effectively enhanced without sacrificing the electrical performance of the inductor. In order to further enhance the insulation performance of the interlayer position, this embodiment uses ultrafine iron-silicon-chromium alloy powder with low porosity to make the internal electric belt, which not only increases the surface area of ​​the oxide film of the interlayer particles, but also reduces the risk of silver migration causing electrode virtual connection short circuit under long-term high temperature and high pressure environment; this embodiment also uses ultrafine iron-silicon-chromium powder with relatively high porosity as the internal electric filling material. The alloy powder with higher porosity not only increases the surface area of ​​the particles, but also promotes the oxidation process of the particles because it can provide a more spacious entry channel for air, thereby increasing the thickness of the oxide film on the surface of the particles. This not only improves the insulation performance between particles, but also strengthens the insulation capacity within the particles.

[0075] In the process of preparing the electrode slurry, high-temperature oxygen-releasing substances such as silver oxide are specially added. These substances release oxygen during the sintering process, which helps to increase the degree of particle oxidation near the inner electrode, especially between layers and at the end, further increasing the thickness of the oxide film in these key areas, thereby further improving the insulation performance.

[0076] Product Testing

[0077] After the product is ground to the specified position, it is ion polished, and a certain proportion of acid is used to immerse and corrode the product surface to expose the oxide film. Finally, a field emission microscope is used to test the oxide film thickness at different positions of the product.

[0078] Table 1 is a performance comparison of the components obtained in the embodiment and the comparative example:

[0079] Table 1

[0080]

[0081] Through the above innovations, the power inductor of the present invention has better insulation performance in the key area close to the electrode, while maintaining the overall electrical performance of the inductor, meeting the demand of modern electronic equipment for high-voltage power inductors.

[0082] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, they can also make several substitutions or modifications to the described embodiments, and these substitutions or modifications should be regarded as belonging to the scope of protection of the present invention. In the description of this specification, the reference terms "one embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" refer to the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In Without contradiction, those skilled in the art can Different reality Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications may be made herein without departing from the scope of protection of the patent application.

Claims

1. A power inductor, characterized in that: It includes a magnet and an inner electrode located inside the magnet, the magnet contains magnet particles, and an oxide film is formed on the surface of the magnet particles, wherein the magnet includes a first region and a second region, the first region is closer to the inner electrode than the second region, the oxide film thickness of the magnet particles in the first region is greater than the oxide film thickness of the magnet particles in the second region, so that the first region has higher insulation performance than the second region.

2. The power inductor according to claim 1, characterized in that: The inner electrode includes multiple layers of coils, and the first region includes a magnet portion between different layers of coils.

3. The power inductor according to claim 2, characterized in that: The first region includes a magnet portion close to an upper surface of the uppermost coil and a magnet portion close to a lower surface of the lowermost coil.

4. The power inductor according to any one of claims 1 to 3, characterized in that: The inner electrode includes a multi-layer coil, and the first region includes a magnet portion located inside the same plane as the coil and a magnet portion located outside the same plane as the coil.

5. The power inductor according to any one of claims 1 to 4, characterized in that: The magnetic particles are iron-silicon-chromium alloy particles or iron-silicon-aluminum alloy particles, and the oxide film is a dense continuous layer composed of oxides of iron, silicon, and chromium or oxides of iron, silicon, and aluminum.

6. The power inductor according to any one of claims 1 to 5, characterized in that: The thickness of the oxide film of the magnetic particles in the first region is 1.2 times or more the thickness of the oxide film of the magnetic particles in the second region.

7. The power inductor according to any one of claims 1 to 6, characterized in that: The first region is within a range of 1.5*C around the inner electrode, where C is the interlayer film thickness.

8. A method for manufacturing a power inductor, characterized in that: include: S1: fine powder magnet particles are used to prepare fine powder slurry, and coarse powder magnet particles are used to prepare coarse powder slurry; S2: using fine powder slurry to cast on the base film to form an internal electro-generated tape, and using coarse powder slurry to cast on the base film to form a substrate tape; S3: Opening holes in the inner electrogenic belt and printing electrode patterns; S4: Printing fine powder slurry on the area of ​​the inner electrogenic tape where the electrode pattern is not printed; S5: According to the set lamination scheme, the multi-layer inner electrical tape and the substrate tape are aligned and laminated together; S6: ultra-high isostatic pressing of the laminated product; S7: Sintering the product after ultra-high isostatic pressing, wherein the thickness of the oxide film of the magnet particles in the first region formed by the fine powder slurry is greater than the thickness of the oxide film of the magnet particles in the second region formed by the coarse powder magnet.

9. The method of claim 8, wherein: In step S1, fine powder magnet particles with a first porosity are used to prepare a fine powder casting slurry, and fine powder magnet particles with a second porosity are used to prepare a fine powder filling slurry, wherein the first porosity is smaller than the second porosity; In step S2, the fine powder casting slurry is cast on the base film to form an internal electrogenic belt; In step S4, the fine powder filling slurry is printed on the area of ​​the inner electrogenerating tape where the electrode pattern is not printed.

10. The production method according to claim 8 or 9, characterized in that: In step S3, a high-temperature oxygen-releasing substance source, such as silver oxide, is added to the electrode slurry used for printing the electrode pattern.

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