A chip transformer and a power module

Abstract

This application relates to the field of transformer technology, specifically to a chip transformer and power module, including a ceramic substrate; the ceramic substrate includes a plurality of stacked ceramic diaphragms; conductive posts are provided on the ceramic diaphragms, the conductive posts extending perpendicularly to the ceramic diaphragms; helical coils are provided on the surface of the ceramic diaphragms, and the ends of adjacent helical coils are connected through the conductive posts; at least two helical coils are connected through the conductive posts to form a coil winding. The embodiments of this application can significantly increase the number of turns in the winding by using planar helical coils, effectively improving the inductance value and enhancing the coupling coefficient between the primary and secondary coils while achieving a miniaturized integrated design.

Description

Technical Field

[0001] This application relates to the field of transformer technology, and more specifically, to a chip transformer and a power module. Background Technology

[0002] As electronic devices evolve towards miniaturization, lightweighting, and high-frequency operation, higher demands are being placed on the size, performance, and integration of electronic components. Traditional transformers often use enameled wire windings, which result in large size, high height, and difficulty in surface mount technology (SMT), limiting their application on high-density circuit boards.

[0003] To address these issues, planar transformer structures based on printed circuit board (PCB) or thin-film processes have emerged in recent years. These transformers typically use etched copper foil to form planar coils and employ a dielectric substrate for interlayer insulation. However, existing planar transformers still suffer from problems such as limited turns, low coupling coefficients between primary and secondary coils, and complex winding connection methods. Utility Model Content

[0004] The purpose of this application is to provide a chip transformer and power module, which can significantly increase the number of winding turns through a planar helical coil, thereby effectively improving the inductance value, enhancing the coupling coefficient between the primary and secondary coils, and achieving a small-scale integrated design.

[0005] The embodiments of this application are implemented as follows:

[0006] In a first aspect, embodiments of this application provide a chip transformer, including a ceramic substrate; the ceramic substrate includes a plurality of stacked ceramic films; conductive posts are provided on the ceramic films, the conductive posts extending perpendicularly to the ceramic films; helical coils are provided on the surface of the ceramic films, and the ends of adjacent helical coils are connected through the conductive posts; at least two helical coils are connected through the conductive posts to form a coil winding.

[0007] In one optional implementation, the helical coil includes a first helical coil and a second helical coil; the first helical coil surrounds the second helical coil; at least two stacked first helical coils are connected by the conductive post to form a primary winding; at least two stacked second helical coils are connected by the conductive post to form a first secondary winding; the primary winding surrounds the first secondary winding.

[0008] As an optional implementation, the helical coil further includes a third helical coil surrounding the first helical coil; at least two stacked third helical coils are connected by the conductive post to form a second secondary winding; the second secondary winding surrounds the primary winding.

[0009] As an optional implementation, the spiral coil is provided with coil connectors at both ends, the ceramic diaphragm is provided with through holes at positions corresponding to the coil connectors, and the conductive post is disposed in the through holes; the coil connectors cover the through holes and are connected to the conductive post.

[0010] As an optional implementation, each coil connector is covered with at least two conductive posts.

[0011] As an optional implementation, a portion of the ceramic diaphragm surface is provided with a transfer connector that connects to the conductive post; the projection of the transfer connector on the ceramic diaphragm is larger than the projection of the conductive post.

[0012] As an optional implementation, the surface of the ceramic diaphragm is provided with an input / output wiring structure for electrical connection with the circuit board; the input / output wiring structure is connected to the intermediate connector.

[0013] As an optional implementation, it also includes two magnetic core assemblies; the ceramic substrate has a central hole; the magnetic core assembly includes a base plate, a central post disposed on the base plate, and side posts disposed on both sides of the base plate; the two magnetic core assemblies are located on both sides of the ceramic substrate, and the two central posts are inserted into the central hole and abut against each other; the side posts of the two magnetic core assemblies abut against each other.

[0014] As an optional implementation, the ceramic substrate has a first recess on each of its opposite sides, and both base plates are embedded in the first recess, so that the base plates are flush with the surface of the ceramic substrate; the ceramic substrate also has a second recess, and the side post is embedded in the second recess, so that the surface of the side post away from the center post is flush with the surface of the ceramic substrate.

[0015] Secondly, embodiments of this application provide a power module, including a circuit board and the aforementioned chip transformer. At least one side surface of the ceramic substrate is provided with pads electrically connected to the windings. The circuit board is attached to the surface of the ceramic substrate and electrically connected to the pads.

[0016] The beneficial effects of the embodiments of this application include:

[0017] This embodiment employs a helical coil design, enabling a higher number of turns within the same area. This directly increases the transformer's inductance, and the turns ratio can be adjusted to optimize transformer performance based on actual needs. This embodiment also enhances coupling efficiency; the helical coil design helps improve magnetic field distribution and reduce leakage flux, thereby increasing the coupling efficiency between the two windings and facilitating efficient energy transfer. Furthermore, this embodiment promotes miniaturization and integration. By integrating the helical coil into a multilayer ceramic substrate, a highly compact component design is achieved, facilitating SMT mounting and making it particularly suitable for high-density circuit board applications. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is one of the structural schematic diagrams of the chip transformer according to an embodiment of this application;

[0020] Figure 2 This is a second schematic diagram of the structure of the chip transformer according to an embodiment of this application;

[0021] Figure 3 This is the third schematic diagram of the structure of the chip transformer according to the embodiments of this application;

[0022] Figure 4 This is the fourth schematic diagram of the structure of the chip transformer according to the embodiments of this application;

[0023] Figure 5 This is the fifth schematic diagram of the structure of the chip transformer according to the embodiments of this application;

[0024] Figure 6 This is the sixth schematic diagram of the structure of the chip transformer in the embodiments of this application.

[0025] Icons: 100-Ceramic substrate; 101-Ceramic diaphragm; 102-Conductive post; 103-Helical coil; 104-First helical coil; 105-Second helical coil; 106-Third helical coil; 107-Coil connector; 108-Transfer connector; 109-Magnetic core assembly; 110-Center hole; 111-Base plate; 112-Center post; 113-Side post; 114-First recess; 115-Second recess; 116-Circuit board; 117-Pad. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0028] It should be noted that similar reference numerals 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. Furthermore, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0029] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] As electronic devices evolve towards miniaturization, lightweighting, and high-frequency operation, higher demands are being placed on the size, performance, and integration of electronic components. Traditional transformers often use enameled wire windings, which result in large size, high height, and difficulty in surface mount technology (SMT), limiting their application on high-density circuit boards.

[0031] To address these issues, planar transformer structures based on printed circuit board (PCB) or thin-film processes have emerged in recent years. These transformers typically use etched copper foil to form planar coils and employ a dielectric substrate for interlayer insulation. However, existing planar transformers still suffer from problems such as limited turns, low coupling coefficients between primary and secondary coils, and complex winding connection methods.

[0032] To address the aforementioned technical problems, embodiments of this application provide a chip transformer and a power module.

[0033] Reference Figure 1 , Figure 2 As shown, the chip transformer provided in this application embodiment includes a ceramic substrate 100; the ceramic substrate 100 includes a plurality of stacked ceramic diaphragms 101; conductive posts 102 are provided on the ceramic diaphragms 101, and the conductive posts 102 extend perpendicularly to the ceramic diaphragms 101; a spiral coil 103 is provided on the surface of the ceramic diaphragms 101, and the ends of adjacent spiral coils 103 are connected through the conductive posts 102; at least two spiral coils 103 are connected through the conductive posts 102 to form a coil winding.

[0034] It should be noted that in this embodiment, ceramic is used as the substrate, and the ceramic substrate 100 is constructed by stacking multiple ceramic films 101. Ceramic materials have excellent electrical insulation, thermal stability, and mechanical strength.

[0035] The ceramic diaphragm 101 is primarily made of non-magnetic aluminum oxide, and can be modified by doping with other materials as needed. This choice not only provides excellent electrical insulation and thermal stability, but also results in minimal self-coupling of the helical coil 103 due to its permeability being close to that of air.

[0036] In this embodiment, vertically extending conductive posts 102 are provided on a ceramic diaphragm 101. Each ceramic diaphragm 101 has a spiral coil on its surface. This design allows for an increase in the number of coil turns within a limited space, improving inductance and coupling efficiency. In this embodiment, the vertically extending conductive posts 102 connect spiral coils 103 on different layers in series, forming a continuous winding path and simplifying the connection method between windings.

[0037] In this embodiment, at least two spiral coils 103 are connected by conductive posts 102 to form a coil winding, which means that different turns ratios can be flexibly designed as needed to adapt to the requirements of various application scenarios.

[0038] It should be noted that the ceramic substrate 100 can be manufactured by sintering, and then the positions for mounting the high-permeability magnetic core can be prepared by punching or CNC machining. After drilling holes in the ceramic substrate 100, the high-permeability magnetic core is fitted in, confining most of the magnetic flux inside the magnetic core, thereby greatly reducing the self-coupling effect between the coils and improving the coupling coefficient between the primary and secondary coils.

[0039] The technical effects that the embodiments of this application can produce are as follows:

[0040] Because this embodiment of the application uses a spiral coil 103 design, a higher number of turns can be achieved in the same area, which directly improves the inductance value of the transformer, and the turns ratio can be adjusted according to actual needs to optimize the transformer performance.

[0041] The embodiments of this application enhance coupling efficiency. The design of the helical coil 103 helps improve the magnetic field distribution and reduce magnetic leakage, thereby increasing the coupling efficiency between the two windings and facilitating efficient energy transfer. Furthermore, due to the use of a non-magnetic ceramic substrate 100 with a permeability close to that of air, the self-coupling effect of the helical coil 103 is significantly reduced, far less than that found in existing LTCF (low-temperature co-fired ceramic) chip transformers. This directly overcomes the problem in current LTCF transformers where self-coupling makes it difficult to improve the coupling coefficients of the primary and secondary coils, significantly improving coupling efficiency.

[0042] The embodiments of this application can promote miniaturization and integration. The spiral coil 103 is manufactured using PCB or thin film processes and integrated into the multilayer ceramic substrate 100, achieving a highly compact design of the component, which is conducive to SMT mounting and is particularly suitable for the application requirements of high-density circuit boards 116.

[0043] The embodiments of this application can simplify the manufacturing process and improve reliability. By connecting the windings through the conductive post 102, the manufacturing process is not only simplified, but also the reliability and consistency of the product are improved, and errors that may be introduced by manual operation are reduced.

[0044] Reference Figure 1 , Figure 2 As shown, in one optional implementation, the spiral coil 103 includes a first spiral coil 104 and a second spiral coil 105; the first spiral coil 104 surrounds the second spiral coil 105; at least two stacked first spiral coils 104 are connected by conductive posts 102 to form a primary winding; at least two stacked second spiral coils 105 are connected by conductive posts 102 to form a first secondary winding; the primary winding surrounds the first secondary winding.

[0045] It should be noted that, as needed, the central axes of the primary winding and the first secondary winding can be aligned.

[0046] It should be noted that since the primary winding completely surrounds the first secondary winding and the two share the same central axis, the magnetic flux path is more direct and effective, greatly enhancing the magnetic coupling efficiency between the two windings.

[0047] It should be noted that the embodiments of this application can improve energy transmission efficiency. The denser winding layout reduces magnetic leakage, improves the energy transmission efficiency from the primary side to the secondary side, and reduces energy loss.

[0048] The embodiments of this application adopt a concentric cylindrical spiral coil 103 layout, which realizes more turns in a limited space, helps to reduce the overall size of the transformer, while maintaining or even improving its electrical performance, meeting the requirements of modern electronic equipment for miniaturization and lightweighting.

[0049] In summary, this implementation method, through a specific winding layout design, not only improves the electrical performance of the transformer but also takes into account miniaturization and manufacturing feasibility, providing an ideal power conversion solution for high-performance electronic devices.

[0050] Reference Figure 1 , Figure 2 As shown, in an optional implementation, the spiral coil 103 further includes a third spiral coil 106 surrounding the first spiral coil 104; at least two stacked third spiral coils 106 are connected by conductive posts 102 to form a second secondary winding; the second secondary winding surrounds the primary winding.

[0051] This embodiment introduces a third helical coil 106, forming a three-layer structure from the inside out: a first secondary winding, a primary winding, and a second secondary winding. All windings share the same central axis. Each layer of helical coil 103 (including the first, second, and third helical coils 106) is electrically connected between layers through conductive posts 102, forming a continuous winding path. The first helical coil 104, the second helical coil 105, and the third helical coil 106 each include multi-turn coils.

[0052] Specifically, at least two stacked first helical coils 104 are connected by conductive posts 102 to form a primary winding, at least two stacked second helical coils 105 form a primary secondary winding, and at least two stacked third helical coils 106 form a secondary secondary winding surrounding the primary winding. This design not only ensures efficient flux transfer between windings, reduces magnetic leakage, and improves overall coupling efficiency, but also supports multi-output requirements, achieving higher integration and performance improvements without significantly increasing size. Furthermore, this structure allows for flexible adjustment of the turns ratio of each winding to meet the transformer ratio requirements of different application scenarios. Through standardized multilayer ceramic substrate 100 technology and conductive post 102 connection methods, the entire manufacturing process maintains a high level of automation and product consistency, which is beneficial for large-scale production.

[0053] Reference Figure 3 As shown, in one optional embodiment, the two ends of the spiral coil 103 are respectively provided with coil connectors 107, the ceramic diaphragm 101 is provided with through holes at positions corresponding to the coil connectors 107, and the conductive post 102 is disposed in the through holes; the coil connectors 107 cover the through holes and are connected to the conductive post 102.

[0054] Reference Figure 3 As shown, each of the two adjacent spiral coils 103 has a coil connector 107 at its end, and the two coil connectors 107 are connected by a conductive post 102. (Refer to...) Figure 2As shown, the first end of the middle spiral coil 103 is electrically connected to the end of the upper spiral coil 103 through a set of conductive posts 102, and the second end of the middle spiral coil 103 is electrically connected to the end of the lower spiral coil 103 through another set of conductive posts 102, so that the three spiral coils 103 are connected in series.

[0055] It should be noted that the coil connector 107 covers the through hole, which not only enables effective conduction between the spiral coil 103 and the conductive post 102, but also forms a certain encapsulation and positioning effect on the conductive post 102 by covering it, thereby enhancing the stability and reliability of the connection.

[0056] The embodiment of this application improves connection reliability by providing the coil connector 107, effectively preventing electrical open circuits caused by misalignment of the conductive post 102, poor contact, or weak soldering, and enhancing the stability of interlayer interconnection. The design of the coil connector covering the through-hole avoids unexpected contact between the top of the conductive post 102 and other metal layers or coil portions, thereby reducing the risk of short circuits and improving the overall safety of the device.

[0057] Reference Figure 3 As shown, in one optional implementation, each coil connector 107 covers at least two conductive posts 102.

[0058] The embodiments of this application can improve the current carrying capacity through the above-described configuration. Since a coil connector 107 connects to multiple conductive posts 102, it is equivalent to providing multiple parallel current channels between layers, effectively reducing the current density per unit conductive post 102 and improving the overall current carrying capacity, making it suitable for high-current applications.

[0059] In this embodiment, multiple conductive posts 102 are connected in parallel, so that even if individual conductive posts 102 experience abnormalities such as poor contact or breakage, the remaining conductive posts 102 can still maintain normal conduction, which significantly improves the reliability of the connection and the fault tolerance of the device.

[0060] In addition, the multi-point connection method helps to reduce the contact resistance between the conductive post 102 and the coil connector 107, thereby reducing power loss and local heat generation, and improving the stability and lifespan of the transformer under high power operation.

[0061] This embodiment achieves a multi-point redundancy structure for the interlayer connection of the helical coil 103 by covering and connecting at least two conductive posts 102 to each coil connector 107. This technical solution not only significantly improves the reliability of the connection and the current carrying capacity, but also reduces contact resistance and thermal resistance, optimizes high-frequency performance, and enhances adaptability to manufacturing errors.

[0062] It should be noted that conductive paste can be filled into the ceramic diaphragm 101 to form conductive pillars 102. The conductive paste can be conductive silver paste or other types of paste, which can be selected by those skilled in the art as needed.

[0063] Reference Figure 3 As shown, in one optional embodiment, a portion of the ceramic diaphragm 101 has a transfer connector 108 connected to the conductive post 102 on its surface; the projection of the transfer connector 108 on the ceramic diaphragm 101 is larger than the projection of the conductive post 102.

[0064] By adding a transfer connector 108 as a transfer transition structure, the conductive post 102 is designed to provide additional anchoring support, thereby enhancing its stability and reliability in the ceramic substrate 100.

[0065] Specifically, the intermediate connector 108 not only serves to connect the conductive post 102, but also provides stronger mechanical support and electrical stability through its larger contact area, preventing the conductive post 102 from shifting, falling off, or failing in other ways during manufacturing or long-term use.

[0066] By strengthening the fixing effect of the conductive post 102, the service life of the entire component can be effectively extended, especially when facing harsh operating conditions such as temperature cycling and vibration. The presence of the intermediate connector 108 makes the overall structure more resistant to long-term working loads and less prone to damage.

[0067] As an optional implementation, the surface of the ceramic diaphragm 101 is provided with an input / output wiring structure for electrical connection with the circuit board 116; the input / output wiring structure is connected to the intermediate connector 108.

[0068] It should be noted that the surface of the ceramic diaphragm 101 of the intermediate connector 108 does not have a spiral coil 103, but instead has an input / output wiring structure. Multiple ceramic diaphragms 101 with input / output wiring structures can be used, and they can be alternately stacked with ceramic diaphragms 101 with spiral coils 103 as needed.

[0069] The design described in this application embodiment not only achieves efficient electrical connections between the layers inside the transformer and between the external circuit board 116, but also, by flexibly combining ceramic diaphragms 101 with different functions (i.e., those including spiral coils 103 and those including input / output wiring structures), the number of turns in the windings can be easily adjusted according to specific needs, thereby optimizing the transformer's performance parameters such as the transformation ratio and inductance value. Furthermore, this modular design not only enhances the flexibility and adaptability of the manufacturing process, but also facilitates customized production and improves the overall integration and reliability of the equipment.

[0070] Reference Figure 4 , Figure 5 As shown, as an optional implementation, it also includes two magnetic core assemblies 109; a central hole 110 is provided on the ceramic substrate 100; the magnetic core assembly 109 includes a base plate 111, a central post 112 provided on the base plate 111, and side posts 113 provided on both sides of the base plate 111; the two magnetic core assemblies 109 are located on both sides of the ceramic substrate 100, and the two central posts 112 are inserted into the central hole 110 and abut against each other; the side posts 113 of the two magnetic core assemblies 109 abut against each other.

[0071] In this embodiment, two symmetrical magnetic core assemblies 109 are provided on both sides of the ceramic substrate 100. Each magnetic core assembly 109 includes a base plate 111, a central post 112 and a side post 113. The central post 112 is inserted into the central hole 110 on the ceramic substrate 100 and abuts against each other, and the side posts 113 also abut against each other, thereby forming a closed and complete magnetic circuit.

[0072] It should be noted that the structure described in this embodiment effectively concentrates the magnetic flux path, reduces magnetic flux leakage, and significantly improves the magnetic coupling efficiency between the primary and secondary windings, thereby improving energy transfer efficiency and reducing leakage inductance. Simultaneously, the closed magnetic circuit design optimizes the transformer's electrical performance, giving it higher inductance, better frequency response characteristics, and superior high-frequency performance, making it suitable for high power density and high-frequency applications. Furthermore, the symmetrical structure of the core assembly 109 not only enhances the overall mechanical stability and vibration resistance of the device but also facilitates assembly, improving production efficiency and product consistency.

[0073] Reference Figure 5 As shown, in one optional embodiment, the ceramic substrate 100 has first recesses 114 on opposite sides, and both bottom plates 111 are embedded in the first recesses 114, making the bottom plates 111 flush with the surface of the ceramic substrate 100; the ceramic substrate 100 also has second recesses 115, and the side posts 113 are embedded in the second recesses 115, making the surface of the side posts 113 facing away from the central post 112 flush with the surface of the ceramic substrate 100. This embodiment effectively reduces the overall size of the chip transformer.

[0074] In this embodiment, the ceramic substrate 100 has first recesses 114 on opposite sides to accommodate the base plate 111 of the magnetic core assembly 109, so that the base plate 111 is flush with the surface of the ceramic substrate 100 after being embedded. Simultaneously, the ceramic substrate 100 also has second recesses 115 to accommodate the side posts 113 of the magnetic core assembly 109, so that the surface of the side posts 113 facing away from the central post 112 is also flush with the surface of the ceramic substrate 100 after being embedded. Through this structural design, the portion of the magnetic core assembly 109 (including the base plate 111 and the side posts 113) that originally protruded from the substrate surface is completely or partially "submerged" in the ceramic substrate 100, effectively reducing the overall size of the device in both the vertical and lateral directions.

[0075] This design significantly reduces the overall size of the surface-mount transformer, improving its space utilization and facilitating a thinner, more compact structure that meets the demands of modern electronic devices for miniaturized and lightweight components. Furthermore, the flush structure between the magnetic core assembly 109 and the ceramic substrate 100 helps improve the product's flatness and assembly consistency, enhancing its compatibility and reliability in automated mounting processes.

[0076] Reference Figure 6 As shown, this application embodiment provides a power module, including a circuit board 116 and the aforementioned chip transformer, referring to... Figure 4 As shown, at least one side surface of the ceramic substrate 100 is provided with a pad 117 electrically connected to the winding, and the circuit board 116 is attached to the surface of the ceramic substrate 100 and electrically connected to the pad 117.

[0077] It should be noted that the circuit board 116 can be a printed circuit board (PCB), which carries other necessary electronic components and circuits, such as control circuits and filters. The circuit board 116 is fixed on the ceramic substrate 100 by a mounting process (such as SMT technology) and is electrically connected to the chip transformer through pads 117.

[0078] This application embodiment integrates the chip transformer directly onto the circuit board 116, reducing the need for additional wiring or connectors required by traditional transformers, simplifying the assembly process, and improving production efficiency.

[0079] In addition, since the circuit board 116 can be directly mounted on the chip transformer and its thickness is effectively controlled, this helps to reduce the overall height of the power module, making the module more compact and suitable for applications with limited space.

[0080] The size of the circuit board 116 can be adjusted as needed. For example, the circuit board 116 is projected to coincide with the surface transformer.

[0081] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A chip transformer, characterized in that, The system includes a ceramic substrate (100); the ceramic substrate (100) includes a plurality of stacked ceramic films (101); the ceramic films (101) are provided with conductive posts (102), the conductive posts (102) extending perpendicular to the ceramic films (101); the surface of the ceramic films (101) is provided with helical coils (103), the ends of adjacent helical coils (103) are connected through the conductive posts (102); at least two helical coils (103) are connected through the conductive posts (102) to form a coil winding.

2. The surface-mount transformer according to claim 1, characterized in that, The spiral coil (103) includes a first spiral coil (104) and a second spiral coil (105); the first spiral coil (104) surrounds the second spiral coil (105); at least two stacked first spiral coils (104) are connected by the conductive post (102) to form a primary winding; at least two stacked second spiral coils (105) are connected by the conductive post (102) to form a first secondary winding; the primary winding surrounds the first secondary winding.

3. The chip transformer according to claim 2, characterized in that, The spiral coil (103) further includes a third spiral coil (106) surrounding the first spiral coil (104); at least two stacked third spiral coils (106) are connected by the conductive post (102) to form a second secondary winding; the second secondary winding surrounds the primary winding.

4. The surface-mount transformer according to any one of claims 1-3, characterized in that, The spiral coil (103) has coil connectors (107) at both ends. The ceramic diaphragm (101) has a through hole at a position corresponding to the coil connector (107). The conductive post (102) is disposed in the through hole. The coil connector (107) covers the through hole and is connected to the conductive post (102).

5. The chip transformer according to claim 4, characterized in that, Each of the coil connectors (107) is covered by at least two conductive posts (102).

6. The chip transformer according to claim 4, characterized in that, A portion of the ceramic diaphragm (101) has a transfer connector (108) on its surface that is connected to the conductive post (102); the projection of the transfer connector (108) on the ceramic diaphragm (101) is greater than the projection of the conductive post (102).

7. The chip transformer according to claim 6, characterized in that, The surface of the ceramic diaphragm (101) is provided with an input / output wiring structure for electrical connection with the circuit board (116); the input / output wiring structure is connected to the intermediate connector (108).

8. The chip transformer according to any one of claims 1-3 and 5-7, characterized in that, It also includes two magnetic core assemblies (109); the ceramic substrate (100) is provided with a central hole (110); the magnetic core assembly (109) includes a base plate (111), a central post (112) provided on the base plate (111) and side posts (113) provided on both sides of the base plate (111); the two magnetic core assemblies (109) are located on both sides of the ceramic substrate (100), and the two central posts (112) are inserted into the central hole (110) and abut against each other; the side posts (113) of the two magnetic core assemblies (109) abut against each other.

9. The surface-mount transformer according to claim 8, characterized in that, The ceramic substrate (100) has a first recess (114) on opposite sides, and the two bottom plates (111) are embedded in the first recess (114) so ​​that the bottom plates (111) are flush with the surface of the ceramic substrate (100); the ceramic substrate (100) also has a second recess (115), and the side post (113) is embedded in the second recess (115) so that the surface of the side post (113) away from the center post (112) is flush with the surface of the ceramic substrate (100).

10. A power supply module, characterized in that, The circuit board (116) and the chip transformer according to any one of claims 1-9 are provided with pads (117) electrically connected to the winding on at least one side surface of the ceramic substrate (100), and the circuit board (116) is attached to the surface of the ceramic substrate (100) and electrically connected to the pads (117).

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