Configurable patch common mode inductor and method of making same

Abstract

This invention discloses a configurable surface mount common mode inductor, comprising a housing, a magnetic core, an epoxy PCB connection cover, and a bottom epoxy resin layer. The housing has an internal groove with a U-shaped winding at its axial center, forming an annular gap between the groove and the U-shaped winding. The magnetic core is disposed within this annular gap. Four mounting slots are symmetrically formed at the top of both side walls of the housing, and SMT surface mount terminals are mounted in these slots. The epoxy PCB connection cover is welded to a support base, thus sealing the magnetic core and U-shaped winding within the housing. The bottom epoxy resin layer is installed at the top of the housing, enclosing the entire housing into a square structure. This structure effectively reduces labor costs, improves manufacturing efficiency, and includes built-in soldering terminals for convenient SMT soldering.

Description

Technical Field

[0001] This invention relates to the field of inductor manufacturing technology, specifically to a configurable surface mount common mode inductor and its manufacturing method. Background Technology

[0002] When electronic devices or systems are in normal operating condition, they are both objects susceptible to electromagnetic interference and sources of external interference. Therefore, the electromagnetic interference generated by electronic devices or systems during normal operation must not exceed certain limits. Standards such as the US FCC standard, the international CISPR22 standard, and the Chinese GB9254 all impose relevant restrictions on common-mode conducted interference and radiation from information technology equipment. To eliminate interference signals input to signal lines and various induced interferences, we must rationally arrange filter circuits to filter common-mode and series-mode interference. Common-mode inductors are a crucial component of these filter circuits.

[0003] Currently, traditional common-mode inductor core manufacturing typically involves insulating the surface of a magnetic material, then directly winding the coil onto it. After winding, it is assembled with an additional plastic casing or mounting plate. These traditional common-mode inductor manufacturing methods inevitably involve a winding process, which primarily determines the labor costs in the product cost. Another, more novel method is to directly use a PCB board to customize the coil winding. However, due to the high cost of its materials, especially in high-current applications, the copper foil thickness design of the PCB board is also very limited, making it extremely expensive and limiting its use to only a few customers. Therefore, labor and material costs have become the "Achilles' heel" of traditional common-mode inductor and PCB-winding type common-mode inductor design. Summary of the Invention

[0004] The purpose of this invention is to provide a configurable surface mount common mode inductor. By designing an independent U-shaped winding and SMT surface mount terminals, the U-shaped winding, SMT surface mount terminals and plastic housing are injection molded together. After molding, the plastic housing has the winding and terminals built-in, avoiding manual winding and automatic mechanical winding processes, and also realizing surface mount installation.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a configurable surface mount common mode inductor, comprising a housing, a magnetic core, an epoxy PCB connection cover, and a bottom epoxy resin layer. The housing is a square plastic box with slots inside. A U-shaped winding is disposed at the axial center of each slot, and an annular gap is formed between the slot and the U-shaped winding. The magnetic core is disposed within the annular gap, and the height of the magnetic core is the same as that of the U-shaped winding. Four mounting slots are symmetrically provided at the top of the two side walls of the housing, and S-type common mode inductors are mounted on the mounting slots. The SMT surface mount terminal is provided. The epoxy PCB connection cover is fixed to the support base by welding, thereby sealing the magnetic core and U-shaped winding inside the housing. The epoxy PCB connection cover has wiring for connecting the winding and providing electrical insulation and supporting the magnetic core. The wiring inside the epoxy PCB connection cover electrically connects the PCB connection cover and the U-shaped winding by welding, and also welds the U-shaped winding and the SMT surface mount terminal together. The bottom epoxy resin layer is installed on the top of the housing, sealing the entire housing to form a square structure.

[0006] Furthermore, the U-shaped winding is composed of several U-shaped bare copper wires.

[0007] Furthermore, the slot is a cylindrical, elliptical, or racetrack-shaped structure.

[0008] Furthermore, the U-shaped winding and terminals are injection molded together with the plastic housing.

[0009] Another object of the present invention is to provide a method for manufacturing a configurable surface-mount common-mode inductor, comprising the following steps:

[0010] 1) Design independent U-shaped windings and SMT surface mount terminals, and then injection mold them together with the plastic housing. At the same time, design slots inside the plastic housing to combine the circular magnetic core and the housing with the U-shaped windings.

[0011] 2) Design an epoxy PCB connection cover and set up wiring inside the epoxy PCB connection cover to obtain common mode inductors with different design requirements. The wiring design of the epoxy PCB connection cover includes the implementation of multi-turn series or multi-turn parallel winding functions.

[0012] 3) Place the epoxy PCB connection cover directly on the magnetic core inside the assembled housing, and then solder it through a solder pot to connect the PCB connection cover and the U-shaped winding. At the same time, solder the PCB leads and the SMT surface mount terminals together.

[0013] 4) Apply a layer of epoxy resin to the epoxy PCB connector cover to provide protection, electrical insulation, and waterproofing for the solder joints.

[0014] Furthermore, in step 1), the U-shaped winding is designed with bare copper wire, or it can be designed with round enameled wire, flat enameled wire, or copper busbar.

[0015] Furthermore, in step 1), the housing can be designed with slots of different shapes, such as cylindrical, elliptical, or "racetrack" shaped slots.

[0016] Furthermore, in step 2), the wiring design of the epoxy PCB connection cover includes implementing multi-turn series or multi-turn parallel winding functions, including but not limited to the following three types:

[0017] The series structure connects four U-shaped windings in series, and the number of windings of the common mode inductor is 4.

[0018] In the series-parallel structure, the two sets of U-shaped windings are first connected in parallel and then connected in series in pairs. The number of windings of the common mode inductor is 2.

[0019] In the parallel structure, four sets of U-shaped windings are connected in parallel to enhance the current capability of the common-mode current. The number of windings of the common-mode inductor is 1.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] By designing a plastic housing structure with "U"-shaped windings and terminals, the magnetic core can be directly encapsulated to provide insulation. The plastic housing can be designed with slots of different shapes, including not only "circular" magnetic core slots, but also "elliptical" or "racetrack" shaped slots. At the same time, this structure can effectively reduce labor costs and improve manufacturing efficiency, while also having built-in soldering terminals to facilitate customers' SMT soldering processes. Attached Figure Description

[0022] Figure 1 This is an exploded view of the configurable surface-mount common-mode inductor described in this invention;

[0023] Figure 2 For the appendix Figure 1 A schematic diagram of the assembly of the housing shown;

[0024] Figure 3 This is a schematic diagram of the circuit connection for the epoxy PCB connection cover plate. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Please see Figure 1 , Figure 2 A configurable surface-mount common-mode inductor includes a housing 1, a magnetic core 2, an epoxy PCB connection cover 3, and a bottom epoxy resin layer 4. The housing 1 is a square plastic box, and a slot 11 is provided inside the housing 1. A U-shaped winding 12 is provided at the axial part of the slot 11. The U-shaped winding 12 is composed of several U-shaped bare copper wires 121. The U-shaped winding 12 is used for part of the winding of the common-mode inductor. The U-shaped winding 12 can also be made of round enameled wire, flat enameled wire, or copper busbar as needed. The housing 1 can be designed with slots of different shapes, including not only "circular" magnetic core slots but also "elliptical" or "racetrack" shaped slots. In this invention, a cylindrical slot structure 11 is used. A circular gap is formed between the slot 11 and the U-shaped winding 12. The magnetic core 2 is placed within the circular gap, and its height is the same as that of the U-shaped winding 12. The magnetic core 2 is used to generate inductance in the common-mode inductor. Four mounting slots 13 are symmetrically opened at the top of the two side walls of the housing 1. SMT surface mount terminals 5 are mounted on the mounting slots 13. To facilitate customer production and improve production efficiency, the SMT surface mount terminal 5 is provided with an epoxy PCB connection cover 3, which is welded to the support base 14 to seal the magnetic core 2 and the U-shaped winding 12 within the housing 1. The epoxy PCB connection cover 3 has internal wiring for connecting the winding and providing electrical insulation and support for fixing the magnetic core. The wiring inside the epoxy PCB connection cover 3 electrically connects the PCB connection cover 3 and the U-shaped winding 12 by welding, and also welds the U-shaped winding 12 and the SMT surface mount terminal 5 together. The bottom epoxy resin layer 4 is installed on the top of the housing 1, enclosing the entire housing 1 to form a square structure. A layer of epoxy resin is applied to the epoxy PCB connection cover 4 to provide protection and electrical insulation for the solder joints.

[0027] As a further improvement of the present invention, the U-shaped winding 12 and the terminal block are injection molded together with the plastic housing 1. The advantage of injection molding together is that it eliminates the winding process, is convenient to produce, has low cost, and can flexibly configure the number of winding coils according to customer needs.

[0028] Based on the above structural features, the present invention integrates the U-shaped winding 12 and the terminal block with the plastic housing 1 through injection molding. After molding, the plastic housing has the winding and terminal block built-in, avoiding manual winding and automatic mechanical winding processes, as well as the magnetic core insulation process. It also realizes the surface mount installation method, which can reduce labor costs and improve manufacturing process efficiency. At the same time, the built-in soldering terminals facilitate the customer's SMT soldering process.

[0029] The fabrication method of the configurable surface-mount common-mode inductor provided above includes the following steps:

[0030] 1) Design an independent U-shaped winding 12 and SMT surface mount terminal 5, and then injection mold the two together with the plastic housing 1. At the same time, design a slot 11 inside the plastic housing 1 to combine the circular magnetic core 2 and the housing 1 with the U-shaped winding 12.

[0031] 2) Design an epoxy PCB connection cover 3, and set up wiring inside the epoxy PCB connection cover 3 to obtain common mode inductors with different design requirements. The wiring design of the epoxy PCB connection cover 3 includes the implementation of multi-turn series or multi-turn parallel winding functions, including but not limited to the following three types:

[0032] like Figure 3 In the diagram, A represents a series structure, connecting four U-shaped windings 12 in series, and the number of windings in the common mode inductor is 4.

[0033] like Figure 3 B in the diagram represents a series-parallel structure. First, the two sets of U-shaped windings 12 are connected in parallel, and then they are connected in series in pairs. The number of windings of the common-mode inductor is 2.

[0034] like Figure 3 C in the diagram represents a parallel structure. First, four sets of U-shaped windings 12 are connected in parallel to enhance the current capability of the common-mode current. The number of windings of the common-mode inductor is 1.

[0035] 3) Place the epoxy PCB connection cover directly on the magnetic core inside the assembled housing 1, and then solder it through a solder pot to connect the PCB connection cover and the U-shaped winding 12. At the same time, solder the PCB lead wires and the SMT surface mount terminals 5 together.

[0036] 4) Apply a layer of epoxy resin to the epoxy PCB connection cover plate 4 to provide protection, electrical insulation, and waterproofing for the solder joints.

[0037] In step 1), the U-shaped winding 12 can be designed not only with bare copper wire, but also with round enameled wire, flat enameled wire, and copper busbar.

[0038] In step 1), the housing 1 can be designed with slots of different shapes, such as cylindrical, elliptical or "racetrack" shaped slots, to avoid the winding process and magnetic core insulation process.

[0039] Based on the above manufacturing method, by designing relevant wiring on the epoxy PCB connecting cover, it can be connected with the U-shaped winding to become a series winding or a parallel winding. This welding design is more conducive to improving automation productivity and product performance reliability.

[0040] 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 in all respects as exemplary and non-limiting, 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 configurable surface mount common mode inductor, comprising a housing (1), a magnetic core (2), an epoxy PCB connection cover (3), and a bottom epoxy resin layer (4), characterized in that: The housing (1) is a square plastic box. The interior of the housing (1) has slots (11). A U-shaped winding (12) is located at the axial center of each slot (11). A circular gap is formed between the slot (11) and the U-shaped winding (12). The magnetic core (2) is located within this circular gap, and its height is the same as the U-shaped winding (12). Four mounting slots (13) are symmetrically located at the top of the two side walls of the housing (1). SMT surface mount terminals (5) are mounted on the mounting slots (13). The U-shaped winding (12) and the SMT surface mount terminals (5) are integrally injection molded with the plastic housing (1). The epoxy PCB connecting cover (3) is fixed to the support base (1) by welding. 4) The magnetic core (2) and the U-shaped winding (12) are sealed inside the housing (1). The epoxy PCB connection cover (3) is provided with wiring for connecting the winding and providing electrical insulation and supporting the magnetic core. The wiring in the epoxy PCB connection cover (3) is configured to realize the multi-turn series and / or multi-turn parallel connection of the U-shaped winding (12). The wiring in the epoxy PCB connection cover (3) electrically connects the PCB connection cover (3) and the U-shaped winding (12) by welding. At the same time, the U-shaped winding (12) and the SMT surface mount terminal (5) are welded together. The bottom epoxy resin layer (4) is installed on the top of the housing (1) to enclose the entire housing (1) to form a square structure.

2. The configurable surface mount common mode inductor according to claim 1, characterized in that: The U-shaped winding (12) is composed of several U-shaped bare copper wires (121).

3. The configurable surface mount common mode inductor according to claim 1, characterized in that: The slot (11) has a cylindrical or elliptical structure.

4. A method for manufacturing a configurable surface-mount common-mode inductor as described in any one of claims 1-3, characterized in that: Includes the following steps: 1) Design an independent U-shaped winding (12) and SMT surface mount terminal (5), and integrally injection mold the U-shaped winding (12) and the SMT surface mount terminal (5) with the plastic housing (1). At the same time, form a slot (11) inside the plastic housing (1) to combine the circular magnetic core (2) and the housing (1) with the U-shaped winding (12). 2) Design an epoxy PCB connection cover (3), and set wiring inside the epoxy PCB connection cover (3). The wiring design of the epoxy PCB connection cover (3) is to realize the multi-turn series and / or multi-turn parallel connection of the U-shaped winding (12) to obtain common mode inductors with different design requirements. 3) Place the epoxy PCB connection cover (3) directly on the magnetic core (2) inside the assembled housing (1), and then solder it through a solder bath to connect the PCB connection cover (3) and the U-shaped winding (12), and also solder the U-shaped winding (12) and the SMT surface mount terminal (5) together. 4) Apply a bottom epoxy resin layer (4) to the epoxy PCB connection cover plate (3) to provide protection, electrical insulation and waterproofing for the solder joints.

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