A double-powder secondary forming integrated inductor structure and a production method thereof

Abstract

The application relates to the technical field of inductors, and particularly discloses a double-powder secondary forming integrated inductor structure, wherein an inner magnet (40) is made of carbonyl iron powder material to ensure excellent saturation current characteristics, and an outer magnet (10) is made of iron-silicon-chromium alloy powder material. The iron-silicon-chromium alloy has excellent corrosion resistance, in the whole inductor structure, the inner magnet (40) is embedded into an outer box (11) through an inner box (41) and connected with the outer magnet (10), and a coil (30) is embedded into a wire slot (43) of the inner magnet (40). The structure effectively physically isolates and protects the inner coil and the outer magnet made of the iron-silicon-chromium alloy powder material, without the need of additional surface treatment procedures such as immersion in rust-proof oil and paint spraying, so that the overall rust-proof capability can be greatly improved. Thus, the common appearance problems such as sagging and uneven thickness in the spraying process can be completely avoided, and the long-term service reliability of the product under harsh working conditions such as high temperature and high humidity can be remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of inductor technology, and in particular to a surface mount inductor structure and its manufacturing method that employs dual-powder composite and secondary pressing molding. Background Technology

[0002] With the rapid development of fields such as artificial intelligence, cloud computing, new energy vehicles, and high-power-density power supplies, the requirements for miniaturization, high current, and high reliability of power modules are becoming increasingly stringent. As a key magnetic component in power conversion circuits, the performance of molded surface-mount inductors directly determines system efficiency and stability. Currently, these inductors commonly use carbonyl powder as the main magnetic powder material due to its excellent saturation current characteristics, which can meet the transient response requirements in high-power-density scenarios.

[0003] However, carbonyl powder has the following obvious drawbacks in practical applications: 1. Carbonyl powder is prone to rusting, requiring additional surface treatment processes such as immersion in rust-preventive oil and spraying, which leads to complex processes, increased costs, and environmental pressures; 2. The high procurement cost of carbonyl powder directly increases the overall material cost of the product; 3. Spraying processes are prone to problems such as sagging and uneven thickness, resulting in unstable rust prevention performance and poor appearance; 4. Traditional single powder cold pressing processes have limitations in balancing high saturation performance, low cost, high rust prevention capability, and high structural strength, making it difficult to meet the long-term reliability and consistency requirements of the above applications. Summary of the Invention

[0004] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide a dual-powder, secondary-molded integrated inductor structure. This structure effectively isolates and protects both the internal coil and the iron-silicon-chromium alloy powder outer magnet, achieving a significant improvement in overall rust resistance without the need for additional surface treatment processes such as immersion in rust-preventive oil or painting. This completely avoids common defects in spraying processes, such as dripping and uneven thickness, and significantly improves the long-term reliability of the product under harsh conditions such as high temperature and high humidity.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A dual-powder secondary molding integrated inductor structure includes: an outer magnet and an inner magnet, a coil disposed between the outer magnet and the inner magnet, and a pair of electrode terminals mounted on the left and right sides of the coil. The outer magnet includes an outer box, and a slot is provided on the upper outer box; the outer magnet is made of iron-silicon-chromium alloy powder. The inner magnet includes an inner box, a cylinder located at the center of the inner box, and a groove between the cylinder and the inner box; the inner magnet is made of carbonyl iron powder; the inner magnet is embedded in the outer box through the inner box and connected to the outer magnet.

[0006] Preferably, the coil includes an outer connector, an outer coil connected to the outer connector, an inner coil disposed inside the outer coil, and an inner connector connected to the inner coil; the outer connector and the inner connector are both disposed on the same side and in the same direction; the outer connector has an outer interface; the inner connector has an inner interface.

[0007] Preferably, the electrode terminal includes a lead wire, two connecting tabs disposed at the ends of the lead wire, and an opening disposed between the two connecting tabs.

[0008] The production method of a two-powder secondary molding integrated inductor structure includes the following steps: Step S01: First, wind the prepared copper wire into an inner coil, and then wind it from the inside out to form an outer coil, making the inner and outer coils the same height, and the two ends of the copper wire on the same side and in the same direction. Finally, open the outer and inner interfaces at both ends to form an outer connector and an inner connector. Finally, weld the two connecting pieces of the two electrode terminals to the outer and inner interfaces respectively to form a whole A. Step S02: Place the whole A into the mold with the carbonyl powder, and use cold pressing to press the whole A and the inner magnet into a one-piece molded product. At this time, the coil in the whole A is just embedded in the wire groove of the inner magnet. Step S03: Place the one-time molded product into a larger mold cavity, fill the surrounding area with alloy powder, and perform secondary pressing to make the alloy powder evenly and tightly cover the product, forming a composite molded product. During this process, the inner magnet is embedded into the outer box through the inner box and connected to the outer magnet. Step S04: Place the composite molded product in an oven for high-temperature baking to improve the bonding strength and stability of the magnets; Step S05: Bend the leads on the electrode terminals and insert them into the slots of the outer magnet. After visual inspection, the final inductor is formed.

[0009] Preferably, the cold pressing pressure in step S02 is 2-4 T / cm. 2 The distance between the inner magnet cavity and the inner tangent circle of the material sheet is controlled between 0.20 and 0.25 mm to ensure smooth coil placement.

[0010] Preferably, the secondary pressure in step S03 is 4-6 T / cm. 2 Between, and the outer alloy powder has a single-sided reserved filling thickness of ≥0.4mm.

[0011] Preferably, the oven baking temperature in step S04 is between 80-180°C.

[0012] Compared with the prior art, this application has the following beneficial effects: 1. This invention employs a dual-magnet structure design—the inner magnet is made of carbonyl iron powder to ensure excellent saturation current characteristics, while the outer magnet is made of iron-silicon-chromium alloy powder. Iron-silicon-chromium alloy itself possesses excellent corrosion resistance. In the entire inductor structure, the inner magnet is connected to the outer magnet via an inner casing embedded in the outer casing, and the coil is embedded in the slot of the inner magnet. This structure effectively isolates and protects both the internal coil and the iron-silicon-chromium alloy powder outer magnet, achieving a significant improvement in overall rust resistance without the need for additional surface treatment processes such as rust-preventive oil immersion or painting. This completely avoids common appearance defects in spray painting processes, such as drips and uneven thickness, while significantly improving the long-term reliability of the product under harsh conditions such as high temperature and high humidity.

[0013] 2. In this invention, the outer magnet uses iron-silicon-chromium alloy powder to replace part of the carbonyl iron powder. The procurement cost of iron-silicon-chromium alloy powder is much lower than that of carbonyl iron powder, which effectively reduces the overall material cost. On the other hand, since there is no need for rust-preventive oil impregnation or spraying surface treatment, the corresponding equipment investment, material consumption and labor costs are saved, the process flow is simplified, the production cycle is accelerated, and the overall manufacturing cost is significantly reduced.

[0014] 3. Traditional single-powder cold pressing processes struggle to simultaneously achieve the aforementioned multiple performance indicators. This invention employs a two-stage molding process. In the first cold pressing, the entire component A and carbonyl powder are pressed into a single-piece molded product (the coil is embedded in the inner magnet's groove). In the second pressing, iron-silicon-chromium alloy powder is filled around the perimeter and uniformly and tightly coated, forming a composite molded product. This process ensures that: the carbonyl iron powder in the outer magnet provides excellent saturation current characteristics, guaranteeing transient response capabilities in high power density scenarios; the iron-silicon-chromium alloy powder in the inner magnet provides rust-proof support and structural strength; and the double-layer magnets achieve a tight bond at the interface through an interlocking structure where the inner box is embedded into the outer box, avoiding the risk of delamination or cracking. The overall structural strength is superior to that of single-powder cold-pressed products. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0016] Figure 1 This is a schematic diagram of the integrated inductor structure of dual-powder secondary molding according to the present invention; Figure 2 for Figure 1 Schematic diagrams of the structures of Chinese and foreign magnets; Figure 3 for Figure 1 Schematic diagram of the middle electrode terminal; Figure 4 for Figure 1 A schematic diagram of the intermediate coil structure; Figure 5 for Figure 1 A schematic diagram of the structure of the inner magnet. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0018] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0019] Unless otherwise defined, the technical or scientific terms used in this patent document shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this patent specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "an," "a," or "the" do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising" or "including" indicate that the element or object preceding "comprising" encompasses the element or object listed following "comprising" or its equivalents, and do not exclude other elements or objects. Terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are used only to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. These terms are only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0020] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, features in the following embodiments can be combined with each other.

[0021] like Figure 1 , Figure 2 and Figure 5As shown, a dual-powder secondary molding integrated inductor structure includes: an outer magnet 10 and an inner magnet 40, a coil 30 disposed between the outer magnet 10 and the inner magnet 40, and a pair of electrode terminals 20 installed on the left and right sides of the coil 30; the outer magnet 10 includes an outer box 11, with a slot 12 provided on the outer box 11; the outer magnet 10 is made of iron-silicon-chromium alloy powder; the inner magnet 40 includes an inner box 41, a cylinder 42 disposed at the center of the inner box 41, and a groove 43 disposed between the cylinder 42 and the inner box 41; the inner magnet 40 is made of carbonyl iron powder; the inner magnet 40 is embedded in the outer box 11 through the inner box 41 and connected to the outer magnet 10.

[0022] Among them, the inner magnet 40 is made of carbonyl iron powder, which is pressed into shape in one step to ensure the high saturation magnetic induction intensity and core electrical performance of the inductor.

[0023] The outer magnet 10 is made of iron-silicon-chromium alloy powder. The iron-silicon-chromium alloy powder is pressed twice on the outside of the inner magnet 40 to form a uniform coating layer, providing rust protection and mechanical strength.

[0024] like Figure 3 As shown, the coil 30 includes an outer connector 31, an outer coil 32 connected to the outer connector 31, an inner coil 33 disposed inside the outer coil 32, and an inner connector 34 connected to the inner coil 33; the outer connector 31 and the inner connector 34 are both disposed on the same side and in the same direction; the outer connector 31 is provided with an outer interface 35; the inner connector 34 is provided with an inner interface 26.

[0025] In this design, the inner coil 33 and the outer coil 32 generate magnetic fields in the same direction when energized, and the magnetic lines of force are superimposed in the same direction within the magnetic core (inner magnet 40). Compared to a single coil, a dual coil can generate a stronger total magnetic flux within the same volume, thereby significantly increasing the inductance.

[0026] Utilizing the advantages of "dual-powder": the magnetic flux generated by the outer coil 32 mainly passes through the outer magnet, while the magnetic flux of the inner coil 33 mainly passes through the inner magnet. This design fully utilizes the saturation characteristics of both magnetic powders, making the overall inductance less prone to saturation under high current and providing stronger resistance to bias current.

[0027] like Figure 4 As shown, the electrode terminal 20 includes a lead 21, two connecting pieces 22 disposed at the ends of the lead 21, and an opening 23 disposed between the two connecting pieces 22.

[0028] Combination Figure 3The coil 30 adopts an integrated winding structure of inner coil 33 and outer coil 32, and the inner connector 34 and outer connector 31 are located on the same side and in the same direction. Combined with the design of the opening 23 between the two connecting pieces 22 on the electrode terminal 20, the welding positioning of the coil and the electrode terminal is more precise and the operation is more convenient. During the cold pressing process, the fit between the coil (30) and the wire groove (43), combined with the process constraint that the distance between the inner magnet 40 cavity and the inner tangent circle of the material sheet is controlled at 0.20~0.25mm, ensures that the coil is placed smoothly and in a consistent position, effectively reducing the performance dispersion between individual products.

[0029] The production method of a two-powder secondary molding integrated inductor structure includes the following steps: Step S01: First, wind the prepared copper wire into an inner coil 33, and then wind it from the inside out to form an outer coil 32, making the inner coil 33 and the outer coil 32 have the same height, and the two ends of the copper wire are on the same side and in the same direction. Finally, open an outer interface 35 and an inner interface 26 at the two ends respectively to form an outer connector 31 and an inner connector 34. Finally, weld the two connecting pieces 22 of the two electrode terminals 20 to the outer interface 35 and the inner interface 26 respectively to form a whole A. Step S02: Place the whole A into the mold with carbonyl powder, and use cold pressing to press the whole A and the inner magnet 40 into a one-piece molded product. At this time, the coil 30 in the whole A is just embedded in the wire groove 43 of the inner magnet 40. Step S03: Place the one-time molded product into a larger mold cavity, fill the surrounding area with alloy powder, and perform secondary pressing to make the alloy powder evenly and tightly cover the product, forming a composite molded product. During this process, the inner magnet 40 is embedded into the outer box 11 through the inner box 41 and connected to the outer magnet 10. Step S04: Place the composite molded product in an oven for high-temperature baking to improve the bonding strength and stability of the magnets; Step S05: Bend the lead 21 on the electrode terminal 20 and insert it into the slot 12 of the outer magnet 10. After visual inspection, the final inductor is formed.

[0030] In step S02, the cold pressing pressure is 2-4 T / cm. 2 The distance between the inner magnet 40 cavity and the inner tangent circle of the material sheet is controlled at 0.20~0.25mm to ensure smooth coil placement.

[0031] In step S03, the secondary pressure is 4-6 T / cm. 2 Between, and the outer alloy powder has a single-sided reserved filling thickness of ≥0.4mm.

[0032] In step S04, the oven baking temperature is between 80-180℃.

[0033] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A dual-powder secondary molding integrated inductor structure, characterized in that, include: An outer magnet (10) and an inner magnet (40), a coil (30) disposed between the outer magnet (10) and the inner magnet (40), and a pair of electrode terminals (20) installed on the left and right sides of the coil (30). The outer magnet (10) includes an outer box (11), and a slot (12) is provided on the upper outer box (11); the outer magnet (10) is made of iron-silicon-chromium alloy powder. The inner magnet (40) includes an inner box (41), a cylinder (42) located at the center of the inner box (41), and a groove (43) located in the cylinder (42) and the inner box (41); the inner magnet (40) is made of carbonyl iron powder; the inner magnet (40) is embedded in the outer box (11) through the inner box (41) and connected to the outer magnet (10).

2. The integrated inductor structure formed by two-stage molding of powder according to claim 1, characterized in that, The coil (30) includes an outer connector (31), an outer coil (32) connected to the outer connector (31), an inner coil (33) disposed inside the outer coil (32), and an inner connector (34) connected to the inner coil (33); the outer connector (31) and the inner connector (34) are both disposed on the same side and in the same direction; the outer connector (31) is provided with an outer interface (35); the inner connector (34) is provided with an inner interface (26).

3. The integrated inductor structure formed by secondary molding of dual powders according to claim 1, characterized in that, The electrode terminal (20) includes a lead (21), two connecting pieces (22) disposed at the end of the lead (21), and an opening (23) disposed between the two connecting pieces (22).

4. The production method of the dual-powder secondary molding integrated inductor structure according to claims 1-3, characterized in that, Includes the following steps: Step S01: First, wind the prepared copper wire into an inner coil (33), and then wind it from the inside out to form an outer coil (32), making the inner coil (33) and the outer coil (32) have the same height, and the two ends of the copper wire are on the same side and in the same direction. Finally, open the outer interface (35) and the inner interface (26) at both ends to form the outer connector (31) and the inner connector (34). Finally, weld the two connecting pieces (22) of the two electrode terminals (20) to the outer interface (35) and the inner interface (26) respectively to form a whole A. Step S02: Place the whole A into the mold with carbonyl powder and use cold pressing to press the whole A and the inner magnet (40) into a one-piece molded product. At this time, the coil (30) in the whole A is just embedded in the wire groove (43) of the inner magnet (40); Step S03: Place the one-time molded product into a larger mold cavity, fill the surrounding area with alloy powder, and perform secondary pressing to make the alloy powder uniformly and tightly cover the product, forming a composite molded product. During this process, the inner magnet (40) is embedded into the outer box (11) through the inner box (41) and connected to the outer magnet (10). Step S04: Place the composite molded product in an oven for high-temperature baking to improve the bonding strength and stability of the magnets; Step S05: Bend the lead wire (21) on the electrode terminal (20) and insert it into the slot (12) of the outer magnet (10). After visual inspection, the final inductor is formed.

5. The production method of the dual-powder secondary molding integrated inductor structure according to claim 4, characterized in that, In step S02, the cold pressing pressure is 2-4 T / cm. 2 The distance between the inner magnet (40) cavity and the inner tangent circle of the material sheet is controlled at 0.20~0.25mm to ensure smooth coil placement.

6. The production method of the dual-powder secondary molding integrated inductor structure according to claim 4, characterized in that, The secondary pressure in step S03 is 4-6 T / cm. 2 Between, and the outer alloy powder has a single-sided reserved filling thickness of ≥0.4mm.

7. The production method of the dual-powder secondary molding integrated inductor structure according to claim 4, characterized in that, In step S04, the oven baking temperature is between 80-180℃.

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