Planar Transformer

Abstract

To provide a planar transformer whose manufacturing cycle is shortened, fault tolerance is high, manufacturing cost is low, and adjustability is high.SOLUTION: A planar transformer 1 includes a magnetic core assembly, at least one printed circuit board 3, and at least one coil module 4. The magnetic core assembly includes a first magnetic core 20 and a second magnetic core 21. The at least one printed circuit board is provided between a first magnetic core and a second magnetic core and includes a first coil. The at least one coil module is provided between the first magnetic core and the second magnetic core, and includes a second coil and an injection molding layer 41. The injection molding layer covers an outer surface of the second coil. The printed circuit board and the coil module are independent elements.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to the field of transformers, and in particular to planar transformers. [Background technology]

[0002] Planar transformers have a significantly reduced core size, especially height, compared to conventional transformers. This feature is very attractive for power supply devices (such as chargers) where space is severely limited, so they are the first choice magnetic element for many power supply devices.

[0003] Current traditional planar transformers are a combination structure of a single substrate and a magnetic core, and the single substrate is a multi-layer structure, and all the coils of the traditional planar transformers are formed on a single substrate, so the single substrate must be made of six or more substrate layers. However, the more layers of the substrate, the more complex the substrate manufacturing process becomes, and the longer the manufacturing cycle of the traditional planar transformers. In addition, the more layers of the substrate, the more complex the process becomes, and the lower the fault tolerance becomes, so the higher the manufacturing cost of the traditional planar transformers becomes. In addition, when the traditional planar transformers need to adjust the interlayer capacitance of the substrate and / or the number of coil turns, etc., the substrate design needs to be adjusted, but the redesign takes time, in other words, a new substrate needs to be used. However, because the manufacturing cycle of the multi-layer substrate used in the traditional planar transformers is long, the manufacturing of the traditional planar transformers takes a lot of time to wait for the new substrate, and the adjustability of the traditional planar transformers is very low.

[0004] Therefore, the most urgent issue to be solved at present is how to develop a planar transformer that overcomes the above problems. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to provide a planar transformer, which includes a printed circuit board and a coil module, which are independent elements, and the coil module includes a first coil and a second coil, so that the planar transformer of the present invention has the advantages of shortening the manufacturing cycle, high fault tolerance, low manufacturing cost, and high adjustability. [Means for solving the problem]

[0006] In order to achieve the above object, an embodiment of the present invention provides a planar transformer including a core assembly including a first core and a second core, at least one printed circuit board disposed between the first core and the second core and including a first coil, and at least one coil module disposed between the first core and the second core and including a second coil and an injection molded layer, wherein the injection molded layer is covered on an outer surface of the second coil, and the printed circuit board and the coil module are each independent elements.

[0007] In order to achieve the above object, an embodiment of the present invention provides a planar transformer including a core assembly including a first core and a second core, at least one printed circuit board provided between the first core and the second core and including a first coil, a magnetic conductive sheet provided between the first core and the second core for leakage inductance, and at least one coil module provided between the first core and the second core and including a second coil and an injection molded layer, wherein the injection molded layer covers at least a portion of an outer surface of the second coil, and the printed circuit board and the coil module are each independent elements.

[0008] In order to achieve the above object, an embodiment of the present invention provides a planar transformer including a magnetic core assembly, at least one printed circuit board, and at least one coil module, wherein the magnetic core assembly includes a first magnetic core, a second magnetic core, and a magnetic pillar, the magnetic pillar being disposed between the first magnetic core and the second magnetic core, the printed circuit board being disposed between the first magnetic core and the second magnetic core, and including a first coil and a first hollow hole, the coil module being disposed between the first magnetic core and the second magnetic core, and including a second hollow hole, a second coil, and an injection molded layer, the injection molded layer covering at least a portion of an outer surface of the second coil, the printed circuit board and the coil module being independent elements, and the magnetic pillar penetrating the first hollow hole and the second hollow hole. Effect of the Invention

[0009] The planar transformer of the present invention includes a printed circuit board and a coil module, which are independent elements, and the printed circuit board includes a first coil and the coil module includes a second coil, so that the planar transformer of the present invention has the advantages of a short manufacturing cycle, high fault tolerance, reduced manufacturing cost, and high adjustability. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a conceptual diagram of an assembled structure of a planar transformer according to a first preferred embodiment of the present invention. [Diagram 2] FIG. 2 is a conceptual exploded structural diagram of the planar transformer shown in FIG. [Diagram 3] 2 is a conceptual diagram of the structure of a second coil of the planar transformer shown in FIG. 1. [Figure 4] FIG. 2 is a conceptual diagram of the internal wiring of the printed circuit board of the planar transformer shown in FIG. [Diagram 5] 1. FIG. 4 is a conceptual structural diagram of a modified example of the second coil of the planar transformer shown in FIG. [Figure 6] FIG. 11 is a conceptual diagram of an assembled structure of a planar transformer according to a second preferred embodiment of the present invention. [Figure 7] FIG. 7 is a conceptual exploded structural diagram of the planar transformer shown in FIG. 6. [Figure 8] FIG. 13 is an exploded structural conceptual diagram of a planar transformer according to a third preferred embodiment of the present invention. [Figure 9A] FIG. 13 is an exploded structural conceptual diagram of a planar transformer according to a fourth preferred embodiment of the present invention. [Figure 9B] FIG. 9B is a conceptual diagram of a partial combination structure of the planar transformer shown in FIG. 9A. [Figure 10] FIG. 13 is an exploded structural conceptual diagram of a planar transformer according to a fifth preferred embodiment of the present invention. [Figure 11] FIG. 13 is an exploded structural conceptual diagram of a planar transformer according to a sixth preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The following description will provide detailed descriptions of the embodiments showing the features and advantages of the present invention. It should be understood that the present invention can have various modifications in different aspects, all without departing from the scope of the present invention, and the description and drawings are illustrative in nature, and are not intended to limit the present invention.

[0012] Referring to Figures 1, 2, 3, 4 and 5, Figure 1 is a schematic diagram of an assembled structure of a planar transformer according to a first preferred embodiment of the present invention, and Figure 2 is a schematic diagram of an exploded structure of the planar transformer shown in Figure 1, a schematic diagram of the structure of a second coil of the planar transformer shown in Figure 1, and a schematic diagram of internal wiring of a printed circuit board of the planar transformer shown in Figure 1. As shown in Figures 1 to 4, the planar transformer 1 of this embodiment can meet the requirements of thinning and high frequency of the circuit, and is suitable for fully automated assembly and testing. The planar transformer 1 includes a magnetic core assembly 2, at least one printed circuit board 3, and at least one coil module 4.

[0013] The core assembly 2 includes a first core 20 and a second core 21, which are located on opposite sides of the planar transformer 1.

[0014] The number of printed circuit boards 3 may be one or more. One printed circuit board 3 is illustrated in FIG. 2. The printed circuit board 3 is provided between the first magnetic core 20 and the second magnetic core 21, and includes a first coil 30 (shown in FIG. 4). The first coil 30 is formed in the printed circuit board 3, and is composed of a trace or a conductor in the printed circuit board 3.

[0015] The number of the coil modules 4 may be one or more. FIG. 2 illustrates one coil module 4. The coil module 4 is provided between the first magnetic core 20 and the second magnetic core 21, and is located between the printed circuit board 3 and the second magnetic core 21. The coil module 4 further includes a second coil 40 and an injection-molded layer 41. The second coil 40 may be a conductive sheet formed by pressing a copper sheet or the like, but is not limited thereto. The injection-molded layer 41 is formed into the second coil 40 by injection molding, and covers at least a part of the outer surface of the second coil 40. The injection-molded layer 41 enables the planar transformer 1 to meet the protection requirements of the safety standards. In this embodiment, the printed circuit board 3 and the coil module 4 are independent elements. That is, the printed circuit board 3 and the coil module 4 are not integrally molded. In another embodiment, the coil module 4 may be located between the first magnetic core 20 and the printed circuit board 3.

[0016] As can be seen from the above, the planar transformer 1 of the present invention includes the printed circuit board 3 and the coil module 4, which are independent elements, the printed circuit board 3 includes the first coil 30, and the coil module 4 includes the second coil 40. Therefore, the planar transformer 1 of the present invention forms the first coil 30 and the second coil 40 by separately designing the coils required for the transformer, and each is located in two independent elements. In this way, the planar transformer 1 of the present invention can reduce the number of layers of the printed circuit board 3 because the second coil 40 is located in the coil module 4, and the number of layers of the printed circuit board 3 is less than the number of layers of a single board of a traditional planar transformer, so that the manufacturing cycle of the planar transformer 1 of the present invention is relatively short, the process of the printed circuit board 3 is simplified, the fault tolerance is high, and the manufacturing cost of the planar transformer 1 can be reduced. Furthermore, the adjustability of the planar transformer 1 of the present invention is also high.

[0017] In some embodiments, the first coil 30 constitutes one of the primary coil and the secondary coil of the planar transformer 1. The second coil 40 constitutes the other of the primary coil and the secondary coil of the planar transformer 1. The thickness of the second coil 40 is 0.01 mm or less. End and may be 1.5 mm or less (preferably, the thickness of the second coil 40 is 0.01 mm or more and 1 mm or less). The number of turns of the second coil 40 is 2 or more. Furthermore, the protective gap of the safety standard between the first coil 30 and the second coil 40 is 0.4 mm, and the protective gap of the safety standard may be realized by the thickness of the injection molded layer 41 or may be realized by the thickness of the printed circuit board 3. Moreover, the thickness of the injection molded layer 41 may be 0.4 mm or more and 0.8 mm or less.

[0018] In some embodiments, the core assembly 2 further includes at least one magnetic pillar, the at least one magnetic pillar including a first side pillar 22, a second side pillar 23, and a center pillar 24. The first side pillar 22 and the second side pillar 23 are located on opposite sides of the core assembly 2, the center pillar 24 is located between the first side pillar 22 and the second side pillar 23, and the first side pillar 22, the second side pillar 23, and the center pillar 24 are located between the first core 20 and the second core 21. 2, each of the first side pillar 22, the second side pillar 23 and the center pillar 24 is composed of two sub-magnetic pillars, one of the sub-magnetic pillars of the first side pillar 22, one of the sub-magnetic pillars of the second side pillar 23 and one of the sub-magnetic pillars of the center pillar 24 are connected to the first magnetic core 20, and the other of the sub-magnetic pillars of the first side pillar 22, the other of the sub-magnetic pillars of the second side pillar 23 and the other of the sub-magnetic pillars of the center pillar 24 are connected to the second magnetic core 21. Note that in other embodiments, the first side pillar 22, the second side pillar 23 and the center pillar 24 may each be composed of a single structure and connected to the first magnetic core 20 or the second magnetic core 21.

[0019] In some embodiments, the printed circuit board 3 includes a first hollow hole 31, and the coil module 4 includes a second hollow hole 42. The first hollow hole 31 penetrates the printed circuit board 3, the second hollow hole 42 penetrates the coil module 4, and the first hollow hole 31 and the second hollow hole 42 are respectively provided at positions corresponding to the center post 24 of the core assembly 2, and when the first core 20 and the second core 21 of the core assembly 2 are respectively coupled to the printed circuit board 3 and the coil module 4 from opposite sides of the planar transformer 1, the center post 24 penetrates the first hollow hole 31 and the second hollow hole 42.

[0020] In another embodiment, the injection molding layer 41 further includes a receiving portion 43 at a position corresponding to the printed circuit board 3, the receiving portion 43 being formed by recessing the surface of the injection molding layer 41, and the shape and size of the receiving portion 43 correspond to the shape and size of the printed circuit board 3. The receiving portion 43 provides a positioning function, so that the printed circuit board 3 is positioned and provided within the receiving portion 43 of the injection molding layer 41.

[0021] In some embodiments, the injection molding layer 41 includes a first terminal portion 44 located on the first side thereof, and the upper and lower surfaces of the first terminal portion 44 are generally parallel to the printed circuit board 3. The planar transformer 1 further includes at least one first connection terminal 5, which may be synchronously provided at the position of the first terminal portion 44 of the injection molding layer 41 when the first connection terminal 5 is formed on the second coil 40 by injection molding in the injection molding layer 41. The first connection terminal 5 is generally perpendicular to the upper and lower surfaces of the first terminal portion 44, and a portion of the first connection terminal 5 is covered by the injection molding layer 41. The first connection terminal 5 is exposed to the upper and lower surfaces of the first terminal portion 44 and extends in a direction perpendicular to the first terminal portion 44. The portion of the first connection terminal 5 exposed to the first terminal portion 44 may be electrically connected to a trace or conductor of the printed circuit board 3 by welding. For example, the first coil 30 may be electrically connected by welding, and the first connection terminal 5 may be inserted into a system board (not shown).

[0022] In some embodiments, the printed circuit board 3 includes at least one notch 32, which is recessed inward from an edge of the printed circuit board 3 adjacent to the first terminal portion 44 and is provided at a corresponding position of the corresponding first connection terminal 5, each notch 32 can accommodate at least a part of the corresponding first connection terminal 5, and at least a part of the first connection terminal 5 is electrically connected to a trace or conductor of the printed circuit board 3. In addition, the notch 32 may have a semicircular structure, but is not limited thereto, and may have different shapes according to actual needs.

[0023] In another embodiment, the injection molding layer 41 includes a second terminal portion 45 located on the second side of the injection molding layer 41, and the first side and the second side of the injection molding layer 41 are opposed to each other. In addition, the upper surface and the lower surface of the second terminal portion 45 are generally parallel to the printed circuit board 3. In addition, the coil module 4 further includes at least one second connection terminal 46 (for example, two second connection terminals 46 shown in FIG. 3), at least a part of the second connection terminal 46 is provided in the second terminal portion 45, and one end of each second connection terminal 46 is connected to a corresponding end of the second coil 40 and provided in the second terminal portion 45. The other end of each second connection terminal 46 is exposed to the upper surface or the lower surface of the second terminal portion 45 and extends in a direction perpendicular to the second terminal portion 45. The two second connection terminals 46 may be inserted into a system board. In some embodiments, the two second connection terminals 46 and the two opposing ends of the second coil 40 may be integrally formed. In other words, the two second connection terminals 46 are formed by extending from the two opposing ends of the second coil 40, and each second connection terminal 46 may be curved at least once by 90 degrees with respect to the corresponding end of the second coil 40 so that the other end of the second connection terminal 46 is exposed on the upper or lower surface of the second terminal portion 45 and extends in a direction perpendicular to the second terminal portion 45.

[0024] In some embodiments, the second coil 40 made of a conductive sheet further includes a surface 400 and a recess 401, and the recess 401 is recessed inward from the surface 400. By providing the recess 401, it is possible to reduce the skin effect and improve the conversion efficiency of the planar transformer 1. In other embodiments, when the second connection terminal 46 is an integrally molded structure with the corresponding end of the second coil 40, the surface of the second connection terminal 46 may also have a recess.

[0025] 1 , the planar transformer 1 may further include a conductive adhesive 6 provided between the core assembly 2 and the printed circuit board 3, and the core assembly 2 and the printed circuit board 3 may be electrically connected to each other by the conductive adhesive 6. In some embodiments, the conductive adhesive 6 is provided approximately between the center of the core assembly 2 and the ground end of the printed circuit board 3.

[0026] Referring to FIG. 4, in some embodiments, the printed circuit board 3 includes at least one auxiliary coil 33 and at least one blocking structure 34 in addition to the first coil 30. The installation positions of each auxiliary coil 33 and each blocking structure 34 may be any one or multiple spaces in the printed circuit board 3, and are not limited to the positions shown in FIG. 4. The auxiliary coil 33 may constitute a control signal line of a circuit, and may constitute a primary coil or a secondary coil of the planar transformer 1 together with the first coil 30. In addition, the wire diameter of the auxiliary coil 33 is equal to or smaller than the wire diameter of the primary coil 30. The blocking structure 34 is a metal conductor structure for suppressing EMI electromagnetic interference. In some embodiments, the printed circuit board 3 includes the first coil 30, and each layer of the printed circuit board 3 may include at least one of the first coil 30, the auxiliary coil 33, and the blocking structure 34.

[0027] FIG. 5 is a structural conceptual diagram of a modified example of the second coil of the planar transformer shown in FIG. 1. In some embodiments, as shown in FIG. 5, at least one second connection terminal 46 may include a first curved portion 460 and a second curved portion 461. The first curved portion 460 is connected between the corresponding end of the second coil 40 and the second curved portion 461, and at least a portion of the first curved portion 460 is provided in the second terminal portion 45. The first curved portion 460 is formed by bending one end of the second coil 40 at least once. The second curved portion 461 is at least partially exposed to the upper or lower surface of the second terminal portion 45 and extends in a direction perpendicular to the second terminal portion 45, and the second curved portion 461 is formed by bending one end of the first curved portion 460 once, so that the second curved portion 461 includes a U-shaped structure 462 in the curved portion. The formation of the U-shaped structure 462 can increase the lead length of the entire second coil 40.

[0028] FIG. 6 is a schematic diagram of a combined structure of a planar transformer according to a second preferred embodiment of the present invention, and FIG. 7 is a schematic diagram of an exploded structure of the planar transformer shown in FIG. 6. As shown in FIGS. 6 and 7, the structure of the planar transformer 1a of this embodiment is similar to the structure of the planar transformer 1 shown in FIG. 1, and the same element symbols represent the same elements, structures, and functions, so that the description will be omitted. However, the second coil 40 of the coil module 4 shown in FIG. 1 is made of a conductive sheet, and the second coil 40a of the coil module 4 of this embodiment is made of a winding, but the injection molding layer 41 is still molded into the second coil 40a by injection molding and covers at least a part of the outer surface of the second coil 40a. In addition, one end of each second connection terminal 46a of the coil module 4 is connected to the corresponding end of the second coil 40a, and each second connection terminal 46a and the corresponding end of the second coil 40 are integrally molded.

[0029] 8 is an exploded structural conceptual diagram of a planar transformer according to a third preferred embodiment of the present invention. As shown in FIG. 8, the structure of a planar transformer 1b of this embodiment is similar to the planar transformer 1 shown in FIG. 1, and the same element symbols indicate the same elements, structures, and functions. The planar transformer 1 shown in FIG. 1 includes one printed circuit board 3, but the planar transformer 1b of this embodiment includes two printed circuit boards 3. One of the printed circuit boards 3 is interposed between the first magnetic core 20 and the coil module 4, and the other printed circuit board 3 is interposed between the second magnetic core 21 and the coil module 4.

[0030] As mentioned above, the number of printed circuit boards and the number of coil modules of the planar transformer of the present invention may be changed arbitrarily according to actual needs, for example, to include two coil modules and one printed circuit board.

[0031] Fig. 9A is an exploded structural conceptual diagram of a planar transformer according to a fourth preferred embodiment of the present invention, and Fig. 9B is a partially assembled structural conceptual diagram of the planar transformer shown in Fig. 9A. The structure of the planar transformer 1c of this embodiment is similar to that of the planar transformer 1b shown in Fig. 8, and the same element symbols represent the same elements, structures, and functions. However, in this embodiment, the planar transformer 1c further includes a magnetic conductive sheet 7 disposed between the first magnetic core 20 and the second magnetic core 21 for leakage inductance.

[0032] In addition, compared with the second coil 40 of the coil module 4 shown in FIG. 1 being composed of a conductive sheet, the second coil 40b of the coil module 4 of this embodiment includes at least one rectangular wire, and the injection molding layer 41 is still molded into the second coil 40b by injection molding, covering at least a part of the outer surface of the second coil 40b. In addition, one end of each second connection terminal 46a of the coil module 4 is connected to the corresponding end of the second coil 40b, and each second connection terminal 46a and the corresponding end of the second coil 40b are integrally molded. In some embodiments, the second coil 40b may be composed of a single rectangular wire or may be composed of multiple rectangular wires. In addition, when the second coil 40b is composed of multiple rectangular wires, the multiple rectangular wires overlap each other.

[0033] In some embodiments, the magnetic conductive sheet 7 may be interposed between one of the printed circuit boards 3 and the coil module 4. The magnetic conductive sheet 7 further includes a third hollow hole 70, which penetrates the magnetic conductive sheet 7 and is provided at a position corresponding to the center pillar 24 of the core assembly 2. When the first core 20 and the second core 21 of the core assembly 2 are coupled to the printed circuit board 3 and the coil module 4, respectively, from opposite sides of the planar transformer 1C, the center pillar 24 penetrates the third hollow hole 70.

[0034] In some embodiments, the two printed circuit boards 3 of the planar transformer 1c shown in Figures 9A and 9B may be located on different sides of the coil module 4, but are not limited thereto. Figure 10 is an exploded structural conceptual diagram of a planar transformer according to a fifth preferred embodiment of the present invention. In some embodiments, the two printed circuit boards 3 of the planar transformer 1c may be located on the same side of the coil module 4.

[0035] Fig. 11 is a conceptual diagram of an exploded structure of a planar transformer according to a sixth preferred embodiment of the present invention. The structure of a planar transformer 1e of this embodiment is similar to that of the planar transformer 1 shown in Fig. 1, and the same element reference numerals indicate the same elements, structures, and functions. However, in this embodiment, the planar transformer 1e further includes a magnetic conductive sheet 7 disposed between the first magnetic core 20 and the second magnetic core 21 for leakage inductance.

[0036] 1 is made of a conductive sheet, the second coil 40c of the coil module 4 of this embodiment is made of a twisted wire, but the injection molding layer 41 is still formed into the second coil 40c by injection molding and covers at least a part of the outer surface of the second coil 40c. One end of each second connection terminal 46a of the coil module 4 is connected to a corresponding end of the second coil 40c, and each second connection terminal 46a is integrally formed with the corresponding end of the second coil 40c.

[0037] In some embodiments, the coil module 4 of this embodiment further includes a winding former 47 on which the second coil 40c is wound, and the injection molded layer 41 is molded on the winding former 47 by injection molding to cover the winding former 47.

[0038] In some embodiments, the stranded wire of second coil 40c may be coated with at least three layers of tape.

[0039] As mentioned above, the present invention relates to a planar transformer, which includes a printed circuit board and a coil module which are independent elements, and the coil module includes a first coil and a second coil, so that the planar transformer of the present invention has the advantages of shortening the manufacturing cycle, high fault tolerance, low manufacturing cost, and high adjustability. [Explanation of symbols]

[0040] 1, 1a, 1b, 1c, 1d, 1e: Planar transformers 2: Core assembly 3: Printed circuit board 4: Coil module 20: 1st core 21: Second magnetic core 30: First coil 40, 40a, 40b, 40c: second coil 41: Injection molding layer 22: First side pillar 23: Second side pillar 24: Center pillar 31: 1st hollow hole 42: 2nd hollow hole 43: Storage unit 44: 1st terminal section 5: First connection terminal 32: Notch 45: 2nd terminal section 46, 46a: Second connection terminal 400: Surface 401: Recess 6: Conductive adhesive 460: First curve 461: Second curved section 462: ∪ shaped structure 33: Auxiliary coil 34: Blocking structure 47: Reel

Claims

1. A planar transformer, the planar transformer including a core assembly, at least one printed circuit board, and at least one coil module; The core assembly includes a first core and a second core, the printed circuit board is provided between the first magnetic core and the second magnetic core and includes a first coil; the coil module is provided between the first magnetic core and the second magnetic core, and includes a second coil and an injection molding layer, the injection molding layer covering at least a portion of an outer surface of the second coil; the printed circuit board and the coil module are independent elements, the injection molding layer includes a receiving portion provided at a position corresponding to the printed circuit board; The housing portion is formed by recessing a surface of the injection molding layer toward the inside, The printed circuit board is positioned within the housing, A planar transformer, wherein the second coil has a thickness of 0.01 mm or more and 1.5 mm or less.

2. 2. The planar transformer according to claim 1, wherein the first coil constitutes one of a primary coil and a secondary coil of the planar transformer, and the second coil constitutes the other of the primary coil and the secondary coil of the planar transformer.

3. the injection-molded layer includes a first terminal portion located on a first side of the injection-molded layer; The upper and lower surfaces of the first terminal portion are parallel to the printed circuit board, The planar transformer further includes at least one first connection terminal; 2. The planar transformer according to claim 1, wherein the first connection terminal is provided on the first terminal portion and a portion of the first connection terminal is covered by the injection molding layer, the first connection terminal is exposed to upper and lower surfaces of the first terminal portion and extends in a direction perpendicular to a direction of the first terminal portion, and the first connection terminal is electrically connected to the first coil.

4. 4. The planar transformer according to claim 3, wherein the printed circuit board includes at least one notch, the notch being recessed inward from an edge portion of the printed circuit board on a side adjacent to the first terminal portion, and the notch accommodates at least a portion of the corresponding first connection terminal.

5. the injection molded layer includes a second terminal portion located on a second side of the injection molded layer opposite the first side, and an upper surface and a lower surface of the second terminal portion are parallel to the printed circuit board; The coil module further includes at least one second connection terminal; 4. The planar transformer according to claim 3, wherein the second connection terminal is provided on the second terminal portion, a portion of which is covered by the injection molding layer, the second connection terminal is further exposed on an upper surface or a lower surface of the second terminal portion, and extends in a direction perpendicular to a direction of the second terminal portion, and the second connection terminal is electrically connected to the second coil.

6. the second connection terminal includes a first curved portion and a second curved portion, the first curved portion is connected between the second coil and the second curved portion, and at least a portion of the first curved portion is provided within the second terminal portion, and the first curved portion is formed by bending one end of the second coil at least once; 6. The planar transformer according to claim 5, wherein at least a portion of the second curved portion is exposed on an upper surface or a lower surface of the second terminal portion and extends in a direction perpendicular to the second terminal portion, and the second curved portion is formed by bending one end of the first curved portion once, and includes a U-shaped structure in the curved portion.

7. 2. The planar transformer according to claim 1, wherein the second coil is formed by pressing a conductive sheet.

8. the second coil further includes a surface and a recess; 8. The planar transformer according to claim 7, wherein the recess is formed by recessing the surface of the second coil inward.

9. 2. The planar transformer of claim 1, further comprising a conductive adhesive disposed between the core assembly and a ground end of the printed circuit board.

10. The printed circuit board is formed of one or more layers, The printed circuit board includes at least one auxiliary coil and at least one interrupting structure; 2. The planar transformer according to claim 1, wherein the auxiliary coil constitutes a control signal line and, together with the first coil, constitutes a primary coil or a secondary coil of a planar transformer, the blocking structure is a metal conductor structure, the printed circuit board includes the first coil, and each layer of the printed circuit board includes at least one of the first coil, the auxiliary coil, and the blocking structure.

11. 2. The planar transformer according to claim 1, wherein the second coil is formed of a winding.

12. A planar transformer, the planar transformer including a core assembly, at least one printed circuit board, a magnetic conductive sheet, and at least one coil module; The core assembly includes a first core and a second core, the printed circuit board is provided between the first magnetic core and the second magnetic core and includes a first coil; the magnetic conductive sheet is provided between the first magnetic core and the second magnetic core for leakage inductance; the coil module is provided between the first magnetic core and the second magnetic core and includes a second coil and an injection molding layer, the injection molding layer covers at least a portion of an outer surface of the second coil; the printed circuit board and the coil module are independent elements, the injection molding layer includes a receiving portion provided at a position corresponding to the printed circuit board; The housing portion is formed by recessing a surface of the injection molding layer toward the inside, The printed circuit board is positioned within the housing, A planar transformer, wherein the second coil has a thickness of 0.01 mm or more and 1.5 mm or less.

13. the injection molded layer includes a first terminal portion located on a first side of the injection molded layer, an upper surface and a lower surface of the first terminal portion being parallel to the printed circuit board; The planar transformer further includes at least one first connection terminal; 13. The planar transformer according to claim 12, wherein the first connection terminal is provided on the first terminal portion, a portion of which is covered by the injection molding layer, and the first connection terminal is further exposed to upper and lower surfaces of the first terminal portion, extending in a direction perpendicular to the first terminal portion, and the first connection terminal is electrically connected to the first coil.

14. the injection-molded layer includes a second terminal portion located on a second side of the injection-molded layer opposite the first side, and an upper surface and a lower surface of the second terminal portion are parallel to the printed circuit board; The coil module further includes at least one second connection terminal; 14. The planar transformer according to claim 13, wherein the second connection terminal is provided on the second terminal portion, a portion of which is covered by the injection molding layer, and the second connection terminal is further exposed to upper and lower surfaces of the second terminal portion, extending in a direction perpendicular to the second terminal portion, and the second connection terminal is electrically connected to the second coil.

15. 14. The planar transformer according to claim 13, wherein the printed circuit board includes at least one notch, the notch being recessed inward from an edge portion of one side of the printed circuit board adjacent to the first terminal portion, and the notch accommodates at least a portion of the corresponding first connection terminal.

16. The planar transformer according to claim 12, wherein the second coil is made of a rectangular wire.

17. 17. The planar transformer according to claim 16, wherein the second coil is formed of a plurality of the rectangular wires, the plurality of the rectangular wires overlapping each other.

18. 13. The planar transformer according to claim 12, wherein the second coil is made of a twisted wire.

19. 20. A planar transformer as claimed in claim 18, characterized in that the stranded wire is coated with at least three layers of tape.

20. 13. The planar transformer according to claim 12, wherein the first coil constitutes one of a primary coil and a secondary coil of the planar transformer, and the second coil constitutes the other of the primary coil and the secondary coil of the planar transformer.

21. 13. The planar transformer according to claim 12, wherein the magnetic conductive sheet is provided between the printed circuit board and the at least one coil module.

22. A planar transformer, the planar transformer including: a core assembly; at least one printed circuit board; and at least one coil module; The magnetic core assembly includes a first magnetic core, a second magnetic core, and a magnetic pillar, the magnetic pillar being disposed between the first magnetic core and the second magnetic core; the printed circuit board is provided between the first magnetic core and the second magnetic core, and includes a first coil and a first hollow hole; the coil module is provided between the first magnetic core and the second magnetic core, and includes a second hollow hole, a second coil, and an injection molding layer, the injection molding layer covering at least a portion of an outer surface of the second coil; the printed circuit board and the coil module are independent elements, and the magnetic pillar passes through the first hollow hole and the second hollow hole; the injection molding layer includes a receiving portion provided at a position corresponding to the printed circuit board; The housing portion is formed by recessing a surface of the injection molding layer toward the inside, The printed circuit board is positioned within the housing, A planar transformer, wherein the second coil has a thickness of 0.01 mm or more and 1.5 mm or less.

23. 23. The planar transformer of claim 22, wherein the planar transformer includes a magnetic conductive sheet, the magnetic conductive sheet being disposed between the first core and the second core for leakage inductance.

24. 24. The planar transformer according to claim 23, wherein the magnetic conductive sheet is provided between the printed circuit board and the at least one coil module.

25. 23. The planar transformer according to claim 22, wherein the second coil is formed by pressing a conductive sheet.

26. 23. The planar transformer of claim 22, wherein the second coil comprises at least one rectangular wire.

27. 23. The planar transformer of claim 22, wherein the second coil is made of a twisted wire.

28. 23. The planar transformer according to claim 22, wherein the first coil constitutes one of a primary coil and a secondary coil of the planar transformer, and the second coil constitutes the other of the primary coil and the secondary coil of the planar transformer.

29. the injection-molded layer includes a first terminal portion located on a first side of the injection-molded layer; The upper and lower surfaces of the first terminal portion are parallel to the printed circuit board, The planar transformer further includes at least one first connection terminal; 23. The planar transformer according to claim 22, wherein the first connection terminal is provided on the first terminal portion, a portion of which is covered by the injection molding layer, and the first connection terminal is further exposed to upper and lower surfaces of the first terminal portion, extending in a direction perpendicular to the first terminal portion, and the first connection terminal is electrically connected to the first coil.

30. The printed circuit board includes at least one notch; 30. The planar transformer according to claim 29, wherein the notch is recessed inward from an edge portion of one side adjacent to the first terminal portion of the printed circuit board, and the notch accommodates at least a part of the corresponding first connection terminal.

31. the injection molded layer includes a second terminal portion located on a second side opposite the first side of the injection molded layer; The upper and lower surfaces of the second terminal portion are parallel to the printed circuit board, The coil module further includes at least one second connection terminal; 30. The planar transformer according to claim 29, wherein the second connection terminal is provided on the second terminal portion and a portion of the second connection terminal is covered by the injection molding layer, the second connection terminal is further exposed on upper and lower surfaces of the second terminal portion and extends in a direction perpendicular to the second terminal portion, and the second connection terminal is electrically connected to the second coil.

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