Chip power transformer and manufacturing method thereof

Abstract

The invention belongs to the technical field of transformer elements, and particularly relates to a chip power transformer and a manufacturing method thereof, and the chip power transformer comprises a first magnetic core side column, a second magnetic core side column, a magnetic core middle column, a magnetic core cover plate and a winding coil which form a closed magnetic circuit; wherein the winding coil is wound on the magnetic core middle column, the first magnetic core side column and the second magnetic core side column are both arranged on the same side of the magnetic core cover plate, and the magnetic core middle column is arranged between the first magnetic core side column and the second magnetic core side column; one side of the first magnetic core side column far away from the magnetic core cover plate and one side of the second magnetic core side column far away from the magnetic core cover plate are respectively provided with a plurality of wire slots for accommodating the end parts of the winding coils, tin bar electrodes are arranged in the wire slots, and the end parts of the winding coils are connected with the corresponding tin bar electrodes.

Description

Technical Field

[0001] The invention belongs to the technical field of transformer components, and particularly relates to a chip power transformer and a manufacturing method thereof. Background Art

[0002] The statements in this section merely provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] In the field of power electronics, the development of power transformers has always revolved around the requirements of miniaturization, high efficiency, and high integration. Currently, traditional power transformers basically adopt a separated core, skeleton, and winding structure, which has disadvantages such as low space utilization, high labor cost, slow production efficiency, and product quality fluctuations with the proficiency of workers, and cannot meet the needs of future industries. At present, there is an urgent need for transformer devices with a compact structure, high stability, high reliability, and high power density in many fields, which requires the implementation of intelligent and automated processes in the production and manufacturing of transformers.

[0004] Currently, power transformers have a high demand for power conversion. Therefore, high-frequency power transformers have become the first choice to improve power density and meet the strict requirements of load and space. In view of the deficiencies of current traditional power transformers, it is urgent to develop a new type of power transformer with high power, large current, high reliability, miniaturization, and automated production to adapt to industrial upgrading.

[0005] Existing transformers mostly adopt a chip structure, that is, a core cover plate and a double-core middle column structure. Among them, the double-core middle column structure includes two core side columns and two core middle columns. The two core middle columns are arranged between the two core side columns, and the winding coil is wound between the two core middle columns. The end of the winding coil is arranged between the core side column and the core cover plate. However, the core cover plate is too thin and is prone to deformation under heat and force. In addition, the double-core middle column structure makes the winding complexity high and the cost high. At the same time, the end of the winding coil is contained between the core side column and the core cover plate, greatly reducing the magnetic path window of the core side column and the core cover plate, resulting in waste of magnetic materials, magnetic flux saturation, and a decrease in the magnetic performance of the device. Summary of the Invention

[0006] To solve the above problems, the present invention proposes a chip power transformer and a manufacturing method thereof. A wire groove is opened at the bottom of the core side column, and a refined electroplated material pad process is adopted in the wire groove, effectively avoiding the phenomenon of pad cracking due to stress, thereby solving the problems of large size and low automation degree of current power transformers, realizing intelligent and automated production, saving a large amount of labor costs, and improving the production efficiency and product quality reliability of the transformer.

[0007] According to some embodiments, the first aspect of the present invention provides a chip power transformer, adopting the following technical scheme:

[0008] A chip power transformer includes a first core side post, a second core side post, a core middle post, a core cover plate, and a winding coil that form a closed magnetic circuit; wherein, the winding coil is wound around the core middle post, the first core side post and the second core side post are both arranged on the same side of the core cover plate, and the core middle post is arranged between the first core side post and the second core side post; on one side of the first core side post away from the core cover plate and on one side of the second core side post away from the core cover plate, a plurality of wire grooves for accommodating the ends of the winding coil are provided, tin block electrodes are arranged in the wire grooves, and the ends of the winding coil are connected to the corresponding tin block electrodes.

[0009] As a further technical limitation, the winding coil includes at least two groups of primary winding coils and at least two groups of secondary winding coils. At least two groups of the primary winding coils are arranged side by side and wound around the core middle post, at least two groups of the secondary winding coils are wound around the primary winding coils side by side, and the ends of the primary winding coils and the ends of the secondary coils are both arranged in the corresponding wire grooves and connected to the corresponding tin block electrodes.

[0010] As a further technical limitation, a solder pad with a multi-layer composite electroplating structure is arranged between the wire groove and the tin block electrode, and the end of the winding coil is located in the corresponding wire groove and connected to the corresponding solder pad.

[0011] Furthermore, the ends of the primary winding coils correspond one by one to the wire grooves for accommodating the ends of the primary winding coils, and two adjacent wire grooves are connected.

[0012] Furthermore, the multi-layer composite electroplating structure includes a silver plating layer, a nickel plating layer, and a tin plating layer from the inside to the outside.

[0013] Furthermore, a copper plating layer is arranged between the silver plating layer and the nickel plating layer.

[0014] As a further technical limitation, the wire groove is arranged in a triangular, semi-circular or rectangular structure.

[0015] Furthermore, the tin block electrode is made of a lead-tin bar, a lead-free tin bar, a high-temperature tin bar, a low-temperature tin bar, a pure tin bar or an alloy tin bar.

[0016] According to some embodiments, the second solution of the present invention provides a method for manufacturing a chip power transformer, and the following technical solutions are adopted:

[0017] A method for manufacturing a chip power transformer, which is used to manufacture the chip power transformer provided by the first solution, includes the following steps:

[0018] Pre-treat the inner wall of the wire groove;

[0019] Electroplate the inner wall of the wire groove to form pads with a multi-layer composite material electroplating structure;

[0020] Wind and fix the primary winding coil and the secondary winding coil in sequence, and weld the ends of the winding coils to the corresponding pads;

[0021] Fill the wire groove with tin liquid to form a tin block electrode, so that the ends of the winding coils are wrapped and fixed inside the tin block electrode;

[0022] Apply glue to fix the magnetic core cover plate, the first magnetic core side post and the second magnetic core side post, and obtain a chip power transformer after baking and curing.

[0023] As a further technical limitation, it also includes using a low-temperature soldering head flattening process or a grinding wheel flattening process to flatten the tin block electrode.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] The present invention opens a wire groove at the bottom of the magnetic core side post and adopts a refined electroplating material pad process in the wire groove, effectively avoiding the phenomenon of pad cracking due to stress, thereby solving the problems of large size and low automation degree of the current power transformer, realizing intelligent and automated production, saving a large amount of labor costs, and improving the production efficiency and product quality reliability of the transformer.

[0026] The pads in the present invention adopt a four-layer composite electroplating pad process, and a multi-layer composite material electroplating structure including a silver-plated bottom layer, a copper-plated intermediate layer, a nickel-plated barrier layer and a tin-plated surface layer from the inside to the outside is electroplated and etched on the inner wall of the wire groove. The stress is dispersed through the multi-layer structure, and the anti-deformation ability of the pads is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The schematic diagrams in the specification forming a part of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments and descriptions of this embodiment are used to explain this embodiment and do not constitute an improper limitation to this embodiment.

[0028] Figure 1 It is a schematic structural diagram of a chip power transformer in Embodiment 1 of the present invention;

[0029] Figure 2 It is a schematic structural diagram of a chip power transformer in Embodiment 1 of the present invention;

[0030] Figure 3 It is a schematic structural diagram of a chip power transformer in Embodiment 1 of the present invention;

[0031] Figure 4 It is an exploded structural diagram of a chip power transformer in Embodiment 1 of the present invention;

[0032] Among them, 1. Core cover plate; 2. First core side post; 3. Second core side post; 4. Core middle post; 5. Fifth coil; 6. Fourth coil; 7. Third coil; 8. Second coil; 9. First coil; 10. Wire groove; 11. Tin block electrode; 12. Pad. Specific implementation manner

[0033] The present invention will be further described below in conjunction with the drawings and embodiments.

[0034] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further descriptions of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0035] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "include" and / or "comprise" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or their combinations.

[0036] In the present invention, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only relationship terms determined for the convenience of describing the structural relationship of each component or element of the present invention and do not specifically refer to any component or element of the present invention and should not be construed as a limitation of the present invention.

[0037] In the present invention, terms such as "fixed connection", "connected", "connected" should be understood in a broad sense, which may mean a fixed connection, an integral connection or a detachable connection; it may be directly connected or indirectly connected through an intermediate medium. For those related scientific research or technical personnel in the field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances and should not be construed as a limitation of the present invention.

[0038] Without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0039] Embodiment 1

[0040] Embodiment 1 of the present invention introduces a chip power transformer.

[0041] Such as Figure 1 、 Figure 2 、 Figure 3 and Figure 4A chip power transformer as shown includes a first magnetic core side post 2, a second magnetic core side post 3, a magnetic core middle post 4, a magnetic core cover plate 1 that forms a closed magnetic circuit, and a winding coil. The winding coil is wound around the magnetic core middle post 4. Specifically, both the first magnetic core side post 2 and the second magnetic core side post 3 are arranged on the same side of the magnetic core cover plate 1. The two ends of the magnetic core cover plate 1 are respectively fixed to the first magnetic core side post 2 and the second magnetic core side post 3 by dispensing glue. The magnetic core middle post 4 is arranged between the first magnetic core side post 2 and the second magnetic core side post 3. On one side of the first magnetic core side post 2 away from the magnetic core cover plate 1 and on one side of the second magnetic core side post 3 away from the magnetic core cover plate 1, a plurality of wire grooves 10 for accommodating the ends of the winding coil are provided. A tin block electrode 11 is arranged in the wire groove 10. The tin block electrode 11 is fixed on a solder pad 12, and the end of the winding coil is connected to the corresponding tin block electrode 11.

[0042] It should be noted that a solder pad 12 with a multi-layer composite material electroplating structure is arranged between the wire groove 10 and the tin block electrode 11. The end of the winding coil is located in the corresponding wire groove 10 and is connected to the corresponding solder pad 12. The end of the primary winding coil corresponds to the wire groove 10 for accommodating the end of the primary winding coil one by one, and two adjacent wire grooves 10 are connected.

[0043] It should be noted that the wire groove 10 is arranged in a triangular, semi-circular or rectangular structure. Among them, one vertex of the triangle is arranged on the first magnetic core side post 2 and the second magnetic core side post 3 close to the magnetic core cover plate 1 side, and one bottom edge of the triangle is arranged on the side surfaces of the first magnetic core side post 2 and the second magnetic core side post 3 away from the magnetic cover plate 1 side. The arc part of the semi-circle is arranged on the first magnetic core side post 2 and the second magnetic core side post 3 close to the magnetic core cover plate 1 side, and the straight part of the semi-circle is arranged on the side surfaces of the first magnetic core side post 2 and the second magnetic core side post 3 away from the magnetic cover plate 1 side. When the wire groove 10 adopts a triangular structure, the connection part of the two inner walls opposite to each other in the wire groove 10 is arranged with an arc transition.

[0044] As one or more embodiments, the winding coil includes at least two groups of primary winding coils and at least two groups of secondary winding coils. At least two groups of primary winding coils are wound side by side around the magnetic core middle post 4. At least two groups of secondary winding coils are wound side by side around the primary winding coils. The ends of the primary winding coils and the ends of the secondary coils are all arranged in the corresponding wire grooves 10 and are connected to the corresponding tin block electrodes 11.

[0045] In this embodiment, the winding coil includes three groups of primary winding coils (i.e., the first coil 9, the second coil 8, and the third coil 7) and two groups of secondary winding coils (i.e., the fourth coil 6 and the fifth coil 5). The three groups of primary coils are wound side by side around the magnetic core middle post 4, and the two groups of secondary coils are wound side by side around the primary coils.

[0046] It should be noted that the tin block electrode 11 can be made of at least one of lead-tin bars, lead-free tin bars, high-temperature tin bars, low-temperature tin bars, pure tin bars, and alloy tin bars. In this embodiment, a lead-free tin bar, a low-temperature tin bar, and an alloy tin bar are selected and melted together to form a tin liquid, which is filled into the wire grooves 10 and solidified to form the tin block electrode 11. The ends of the winding coils are arranged in a plurality of wire grooves 10 and fixedly connected to the tin block electrode 11.

[0047] In this embodiment, the magnetic core cover plate 1, the first magnetic core side column 2, the second magnetic core side column 3, and the magnetic core middle column 4 form a closed magnetic circuit. The magnetic core cover plate 1 can be made of various materials such as soft magnetic alloys, amorphous nanocrystals, Ni-Zn ferrites, and Mn-Zn ferrites, and can be proportionally set according to actual requirements.

[0048] It should be noted that a solder pad 12 attached to the inner wall surface of the wire groove 10 is provided between the wire groove 10 and the tin block electrode 11. The solder pad 12 is a multi-layer composite material electroplating structure to enhance the anti-deformation ability of the solder pad 12 and reduce the occurrence of cracking caused by PCB board stress. Specifically, the solder pad 12 includes a silver plating layer, a nickel plating layer, and a tin plating layer.

[0049] In this embodiment, the silver plating layer is electroplated as the bottom layer on the inner wall of the wire groove, the nickel plating layer is a barrier layer, and the silver plating layer is sequentially arranged on the silver plating layer. In addition, a copper plating layer is provided between the nickel plating layer and the silver plating layer. Among them, the thickness range of the silver plating layer can be set to 12.1 - 12.3 μm, the thickness range of the copper plating layer can be set to 3.17 - 3.37 μm, the thickness range of the nickel plating layer can be set to 6.82 - 7.01 μm, and the thickness of the tin plating layer can be set to 20.08 - 21.18 μm. It should be noted that the wire grooves for accommodating the ends of the primary winding coils are connected, and the solder pads in the wire grooves are also connected to serve as a common electrode terminal for the ends of the primary winding coils to be welded and fixed. The wire grooves for accommodating the ends of the secondary winding coils correspond one-to-one to the ends of the secondary winding coils, and the solder pads in the wire grooves are welded and fixed to the ends of the secondary winding coils one-to-one.

[0050] Embodiment 2

[0051] Embodiment 2 of the present invention introduces a manufacturing method of a chip-type power transformer.

[0052] A manufacturing method of a chip-type power transformer for manufacturing the chip-type power transformer introduced in Embodiment 1 includes the following steps:

[0053] Step S01: Pretreat the inner wall of the wire groove;

[0054] Step S02: Electroplate the inner wall surface of the wire groove to form a solder pad with a multi-layer composite material electroplating structure;

[0055] Step S03: Wind and fix the primary winding coil and the secondary winding coil in sequence, and place the ends of the winding coils on the corresponding pads.

[0056] Step S04: Fill the tin liquid into the wire grooves to form tin block electrodes, so that the ends of the winding coils are wrapped and fixed inside the tin block electrodes.

[0057] Step S05: Glue and fix the magnetic core cover plate to the first magnetic core side post and the second magnetic core side post respectively, and bake and cure to obtain a chip power transformer.

[0058] In step S01, after degreasing the inner wall of the wire groove with an alkaline solution, micro-etching and roughening the inner wall of the wire groove with a mixture of sulfuric acid and hydrogen peroxide, and then activating with colloidal palladium, the pretreatment is completed.

[0059] In this embodiment, first perform pretreatment on the inner wall of the wire groove at the bottom of the magnetic core side post to be electroplated. Specifically: perform degreasing treatment with an alkaline solution, micro-etch and roughen the inner wall of the wire groove with a mixture of sulfuric acid and hydrogen peroxide, and then activate with colloidal palladium, thus completing the pretreatment. In other embodiments, other solutions can be used for pretreatment of the inner wall of the wire groove.

[0060] In step S02, it should be noted that the pads obtained in this embodiment are sequentially provided with a silver plating layer, a copper plating layer, a nickel plating layer and a tin plating layer from the inside to the outside and are electroplated on the surface of the inner wall of the wire groove; specifically, cyanide silver plating is used as the bottom layer, then high-cyanide silver plating is used as the thickening layer, and finally benzotriazole passivation is used to prevent discoloration of the thickening layer, that is, a silver plating layer is formed.

[0061] In this embodiment, cyanide silver plating is used as the bottom layer, then high-cyanide silver plating is used as the thickening layer, and finally benzotriazole passivation is used to prevent discoloration of the thickening layer, thereby forming a silver plating layer; in other embodiments, other silver plating processes can be used for the silver plating bottom layer.

[0062] In this embodiment, the copper plating process for the copper intermediate layer is acidic sulfate; in other embodiments, other copper plating processes can be used for the copper intermediate layer.

[0063] In this embodiment, the nickel plating process for the nickel barrier layer is to use a Watts nickel plating solution; in other embodiments, other nickel plating processes can be used for the nickel barrier layer.

[0064] In this embodiment, the tin plating process for the tin surface layer is to use a tin methyl sulfonate solution; in other embodiments, other tin plating processes can be used for the tin surface layer.

[0065] In step S03, in this embodiment, enameled wire with a selectable specification of 0.3 mm is selected as the winding coil. Among them, the number of turns of the primary winding coil and the secondary winding coil is set according to actual requirements. The first coil 9, the second coil 8, and the third coil 7 are the primary winding coils, and the fourth coil 6 and the fifth coil 5 are the secondary winding coils; when winding on the middle post of the magnetic core by an automatic winding machine, the first coil, the second coil, and the third coil are wound side by side, and the fourth coil and the fifth coil are wound side by side on the primary coil.

[0066] It should be noted that the first coil, the second coil, the third coil, the fourth coil, and the fifth coil all adopt a clockwise winding method; after the winding of the winding coil is completed, the end of the winding coil is fixed on the corresponding pad by the pressure welding head of the automatic winding machine, and the cutting knife on the automatic winding machine cuts the winding coil to break the winding coil; finally, ultraviolet laser is used to strip the paint film at the end of the winding coil to expose the copper substrate.

[0067] It should be noted that the pads to which the leads of the first coil, the second coil, and the third coil in this embodiment are fixed are connected to each other and serve as a common electrode terminal; after the coil group is pre-welded and fixed, laser film removal is used to remove the paint film.

[0068] In this embodiment, ultraviolet laser is used to finely remove the paint film of the enameled wire; the laser film removal is a single laser; in other embodiments, other methods can be adopted.

[0069] In step S04, in this embodiment, tin liquid is filled into the wire groove to wrap the lead, and then the tin block electrode is flattened by a low-temperature welding head or ground flat by a grinding wheel, so that the tin block electrode is flatly arranged in the wire groove to ensure the flatness of the overall transformer on the PCB board.

[0070] In this embodiment, a tin bar and a soldering head are used to fill the tin liquid into the wire groove at the bottom of the side post of the magnetic core and wrap the lead; the tin bar can adopt a lead-free low-temperature tin bar with a diameter of 0.5 mm to 1 mm; the tin block electrode at the bottom of the side post of the magnetic core is flattened by using a 200 °C low-temperature welding head or a grinding wheel grinding process to ensure the flatness after the overall device is on the PCB board.

[0071] It should be noted that the low-temperature welding head simultaneously welds and presses all the tin block electrodes at the bottom end of the side post of the magnetic core to ensure the flatness of all the electrodes.

[0072] In step S05, in this embodiment, the magnetic core cover plate is fixed to the first magnetic core side post and the second magnetic core side post by means of dispensing; after dispensing, the required chip power transformer is obtained through baking.

[0073] During the dispensing process, through the magnetic core cover plate and the integrated magnetic core structure, baking and curing are carried out to obtain a chip power transformer. It should be noted that the magnetic core cover plate and the integrated magnetic core structure are bonded with glue, and the glue selected is air gap glue. The glue is dispensed on the side columns of the magnetic core, and the magnetic core cover plate is fitted and wiped against the side columns of the magnetic core to make the glue evenly distributed.

[0074] It should be noted that the dispensing glue in this embodiment uses particulate air gap glue. In other embodiments, other dispensing glues can be used.

[0075] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0076] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

[0077] The above description is only the preferred embodiment of this example and is not used to limit this example. For those skilled in the art, this example can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this example shall be included within the protection scope of this example.

Claims

1. A chip power transformer, characterized in that, It includes a first magnetic core side post, a second magnetic core side post, a magnetic core middle post, a magnetic core cover plate, and a winding coil that form a closed magnetic circuit; wherein, the winding coil is wound around the magnetic core middle post, the first magnetic core side post and the second magnetic core side post are both arranged on the same side of the magnetic core cover plate, and the magnetic core middle post is arranged between the first magnetic core side post and the second magnetic core side post; on one side of the first magnetic core side post away from the magnetic core cover plate and on one side of the second magnetic core side post away from the magnetic core cover plate, a plurality of wire grooves for accommodating the ends of the winding coil are provided, tin block electrodes are arranged in the wire grooves, and the ends of the winding coil are connected to the corresponding tin block electrodes.

2. A chip power transformer as described in claim 1, characterized in that, The winding coil includes at least two groups of primary winding coils and at least two groups of secondary winding coils. At least two groups of the primary winding coils are arranged side by side around the magnetic core middle post, and at least two groups of the secondary winding coils are wound side by side around the primary winding coils. The ends of the primary winding coils and the ends of the secondary coils are both arranged in the corresponding wire grooves and connected to the corresponding tin block electrodes.

3. A chip power transformer as described in claim 1, characterized in that, A pad with a multi-layer composite electroplating structure is arranged between the wire groove and the tin block electrode, and the end of the winding coil is located in the corresponding wire groove and connected to the corresponding pad.

4. A chip power transformer as described in claim 2, wherein, The ends of the primary winding coils correspond one by one to the wire grooves for accommodating the ends of the primary winding coils, and two adjacent wire grooves are connected.

5. A chip power transformer as described in claim 3, characterized in that, The multi-layer composite electroplating structure includes a silver plating layer, a nickel plating layer, and a tin plating layer from the inside to the outside.

6. A chip power transformer as described in claim 5, characterized in that, A copper plating layer is arranged between the silver plating layer and the nickel plating layer.

7. A chip power transformer as described in claim 1, characterized in that, The wire groove is arranged in a triangular, semi-circular or rectangular structure.

8. A chip power transformer as described in claim 1, characterized in that, The tin block electrode is made of a lead-tin bar, a lead-free tin bar, a high-temperature tin bar, a low-temperature tin bar, a pure tin bar or an alloy tin bar.

9. A manufacturing method of a chip power transformer, which is used to manufacture the chip power transformer according to any one of claims 1-8, characterized in that, It includes the following steps: Pre-treat the inner wall of the wire groove; Electroplate the inner wall surface of the wire groove to form a pad with a multi-layer composite electroplating structure; Wind and fix the primary winding coils and the secondary winding coils in sequence, and weld the ends of the winding coils to the corresponding pads; Fill the wire groove with tin liquid to form a tin block electrode, so that the ends of the winding coil are wrapped and fixed in the tin block electrode; Glue and fix the magnetic core cover plate, the first magnetic core side post and the second magnetic core side post, and obtain a chip power transformer after baking and curing.

10. The manufacturing method of a chip power transformer as described in claim 9, characterized in that, It also includes flattening the tin block electrode with a low-temperature soldering head or grinding it flat with a grinding wheel.

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