High-density planar transformer

Abstract

The invention provides a high-density planar transformer. The high-density planar transformer comprises a multi-layer circuit board, a plurality of windings and a plurality of leading-out terminals. The multiple layers of circuit boards are sequentially arranged in the first direction and comprise the first circuit board and the second circuit board which are oppositely arranged on the outermost side. The plurality of windings are respectively arranged on different layers of the multilayer circuit board, and the plurality of leading-out terminals are connected with the windings in a one-to-one correspondence manner. According to the invention, the at least two leading-out terminals are respectively arranged at the two sides of the multilayer circuit board in the first direction, and the layout of the leading-out terminals is changed from a two-dimensional plane to a three-dimensional space, so that the problem that a strict safety distance must be met because all the leading-out terminals are located at the same side is fundamentally avoided; the projection area of the transformer on the printed circuit board is obviously reduced, and high-density design is achieved.

Description

Technical Field

[0001] This invention relates to the field of electronic equipment, and more particularly to a high-density planar transformer. Background Technology

[0002] In the field of modern power electronics, motor controllers require stable and reliable isolated power supplies to power their internal power module drive circuits, and isolation transformers are key components for achieving this function. Compared with traditional wound-frame transformers, planar transformers, whose windings are manufactured using printed circuit boards (PCBs), have significant advantages such as better parameter consistency, lower height, and easier automated production, and are better able to meet the high power density and high reliability requirements of modern electronic equipment.

[0003] However, existing planar transformer designs, especially for multi-output applications, still have significant shortcomings. Their planar windings typically employ through-hole technology, penetrating the entire circuit board, to electrically lead out the windings. When the transformer requires multiple isolated output windings, each winding needs at least one such through-hole. In high-voltage applications, these through-holes located on the same side panel must adhere to strict safety creepage distance requirements, resulting in the windings not being able to be compactly arranged and must be spaced far apart. This significantly increases the overall projected area of ​​multiple output windings, severely eroding the effective usable space on the PCB.

[0004] Therefore, although planar transformers have significant advantages in the vertical dimension, their large horizontal footprint has become a bottleneck restricting their further application in compact devices. Summary of the Invention

[0005] In order to overcome the above-mentioned technical defects, the purpose of this invention is to provide a high-density planar transformer.

[0006] This invention discloses a high-density planar transformer, which includes a multilayer circuit board, multiple windings, and multiple lead-out terminals; The multilayer circuit board is arranged sequentially along a first direction, including a first circuit board and a second circuit board; the first circuit board and the second circuit board are located on the outermost side of the multilayer circuit board and are arranged opposite to each other in the first direction. Each of the multiple windings is located on a different layer of a multilayer circuit board; Multiple leads are provided in a one-to-one correspondence with multiple windings, with one end electrically connected to the winding and the other end used for electrical connection with other components; at least two of the multiple leads are respectively provided on both sides of the multilayer circuit board in the first direction.

[0007] Preferably, the multiple lead-out terminals are connectors fixedly disposed on the surface of the circuit board, and the multiple windings are led outward through the connectors to be electrically connected to other components.

[0008] Preferably, the plurality of windings includes a first winding and a second winding; the first winding is disposed on the first circuit board; and the second winding is disposed on the second circuit board. The plurality of lead-out terminals include a first connector and a second connector; the first connector is electrically connected to the first winding for leading out the first winding and is electrically connected to other components; the second connector is electrically connected to the second winding for leading out the second winding and is electrically connected to other components. One of the first winding and the second winding is the primary winding, and the other winding is the secondary winding; or, the first winding and the second winding together constitute the primary winding of the planar transformer.

[0009] Preferably, the multiple leads are blind holes, and the walls of the blind holes are electroplated to achieve electrical connection; the blind holes are located at the center of the winding.

[0010] Preferably, the plurality of windings includes a first winding and a second winding, the first winding and the second winding are arranged at a distance from each other in a first direction, and the first winding is arranged on the side closer to the first circuit board, and the second winding is arranged on the side closer to the second circuit board. The blind via includes a first blind via and a second blind via; one end of the first blind via is electrically connected to the first winding, and the other end extends to the surface of the first circuit board; one end of the second blind via is electrically connected to the second winding, and the other end extends to the surface of the second circuit board.

[0011] Preferably, the plurality of windings includes a first winding, a second winding, and a third winding; the first winding and the second winding are disposed on the side closer to the first circuit board; the third winding is disposed on the side closer to the second circuit board; The blind via includes a first blind via, a second blind via, and a third blind via; one end of the first blind via is electrically connected to the first winding, and the other end extends to the surface of the first circuit board; one end of the second blind via is electrically connected to the second winding, and the other end extends to the surface of the first circuit board; one end of the third blind via is electrically connected to the third winding, and the other end extends to the surface of the second circuit board.

[0012] Preferably, the ratio of the depth to the diameter of the blind hole is 1:1.

[0013] Preferably, the planar transformer is used in an electrical control system with a voltage of 800V or higher; the distance between the first blind hole and the second blind hole on a plane perpendicular to the first direction is greater than or equal to 4.5mm.

[0014] Preferably, the planar transformer further includes a primary winding and a magnetic core; the magnetic core penetrates the multilayer circuit board perpendicularly along a first direction, and the primary winding is wound around the magnetic core.

[0015] Compared with existing technologies, the above technical solution has the following advantages: 1. The planar transformer provided in this application transforms the two-dimensional planar layout into a three-dimensional spatial layout by distributing the lead terminals of multiple windings on the inner layers and / or opposite sides of a multilayer circuit board. This fundamentally avoids the problem of all lead terminals having to meet strict safety distances due to being located on the same side. Therefore, the projected area of ​​the transformer on the printed circuit board is significantly reduced, achieving a high-density design. This layout is particularly advantageous in high-voltage applications, maintaining the compactness of the overall structure while meeting stringent electrical insulation requirements, thus enabling the miniaturization of electronic devices. 2. Furthermore, this application provides two solutions. One is to use surface-mount connectors as lead-out terminals. This solution is low-cost and easy to implement, and it simplifies the manufacturing process, reduces manufacturing costs, and provides flexibility for winding lead-out. It is suitable for cost-sensitive applications while ensuring connection reliability. The other solution uses blind vias as lead-out terminals, which makes the transformer body flatter and more integrated in the vertical direction, and it does not require specific winding locations, offering good design flexibility. 3. Furthermore, by optimizing the layout of different windings with the circuit boards on both sides and blind vias, optimal safety and space utilization can be achieved. Since the blind via openings are distributed on both sides, they can be as close as possible, even nearly overlapping, in the projection direction, thereby minimizing the board area occupied. 4. Furthermore, by reasonably limiting the key process parameters of the blind vias, the robustness and consistency of the internal electrical connections are ensured, enabling the planar transformer to be manufactured using conventional processes, achieving both high performance and high yield. Simultaneously, the solution is clearly applicable to high-voltage operating environments, meeting stringent safety specifications while achieving miniaturization and high density. Attached Figure Description

[0016] Figure 1 This is a top view of a planar transformer in the prior art; Figure 2 This is a front view schematic diagram of a planar transformer in the prior art; Figure 3 This is a schematic diagram of the winding projection area of ​​a planar transformer in the prior art; Figure 4 This application provides a front view structural schematic diagram of one implementation of a planar transformer; Figure 5 This application provides a schematic diagram of the projected area of ​​one implementation of a planar transformer; Figure 6 A front view structural schematic diagram of another implementation of a planar transformer for this application; Figure 7A schematic diagram of the projected area of ​​another implementation of the planar transformer for this application; Figure 8 A front view structural schematic diagram of another implementation of a planar transformer for this application; Figure 9 This provides a schematic diagram of the projected area for another implementation of a planar transformer in this application.

[0017] Figure reference numerals: 100, planar transformer; 1. Circuit board; 11. First circuit board; 12. Second circuit board; 2. Winding; 21. First winding; 22. Second winding; 23. Third winding; 3. Lead-out terminals; 41. First connector; 42. Second connector; 51. First blind hole; 52. Second blind hole; 53. Third blind hole; z, First direction. Detailed Implementation

[0018] The advantages of the present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments.

[0019] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0020] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0021] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0022] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0024] In the following description, suffixes such as "module," "part," or "unit" used to denote elements are used only for the convenience of the description of the invention and have no specific meaning in themselves. Therefore, "module" and "part" can be used interchangeably.

[0025] Please see Figures 1-3 , Figure 1 This is a top view of a planar transformer in the prior art; Figure 2 This is a front view schematic diagram of a planar transformer in the prior art; Figure 3 This is a schematic diagram of the projected area of ​​a planar transformer in the prior art.

[0026] like Figures 1-3 As shown, in existing planar coils, the winding radius of each turn gradually increases with the number of turns; and each planar winding has at least one hole for leading out the winding. When a planar transformer has multiple planar output windings (as shown in the figure, each winding occupies a circular area of ​​radius R), its planar windings are usually electrically led out using through-hole technology that penetrates the circuit board. When the transformer requires multiple isolated output windings, each winding requires at least one such through-hole. In high-voltage applications, these through-holes located on the same side panel surface must comply with strict safety creepage distance requirements (shown as 's' in the figure), resulting in the windings not being able to be compactly arranged on the board and having to be spaced far apart. This significantly enlarges the overall projected area of ​​multiple output windings, severely eroding the effective usable space of the PCB.

[0027] Therefore, although planar transformers have significant advantages in the vertical dimension, their large horizontal footprint has become a bottleneck restricting their further application in compact devices.

[0028] Please see Figures 4-5 , Figure 4 This application provides a front view structural schematic diagram of one implementation of a planar transformer; Figure 5 A schematic diagram of the projected area of ​​one implementation of a planar transformer is provided for this application.

[0029] like Figures 4-5 As shown, in order to address this problem, the present invention discloses a high-density planar transformer 100, which includes a multilayer circuit board 1, multiple windings 2 and multiple lead-out terminals 3; The multilayer circuit board 1 is arranged sequentially along the first direction z, including a first circuit board 11 and a second circuit board 12; the first circuit board 11 and the second circuit board 12 are located on the outermost side of the multilayer circuit board 1 and are arranged opposite to each other in the first direction z. Each of the multiple windings 2 is disposed on a different layer of the multilayer circuit board 1; Multiple lead-out terminals 3 are arranged one-to-one with multiple windings 2, with one end electrically connected to the winding 2 and the other end used for electrical connection with other components; at least two lead-out terminals 3 of the multiple lead-out terminals 3 are respectively arranged on both sides of the multilayer circuit board 1 in the first direction z.

[0030] This can be understood as follows: Compared with existing technologies, this application adopts a method of using lead-out terminals 3, by placing the lead-out terminals 3 of multiple windings 2 on opposite sides of the multilayer circuit board 1, shifting from a two-dimensional planar layout to a three-dimensional spatial layout. This fundamentally avoids the problem that all lead-out terminals 3 must meet strict safety distances due to being located on the same side. Therefore, the projected area of ​​the transformer on the printed circuit board is significantly reduced, achieving a high-density design. This layout is particularly advantageous in high-voltage applications, maintaining the compactness of the overall structure while meeting stringent electrical insulation requirements, thus enabling the miniaturization of electronic devices.

[0031] The above is an explanation of the basic concept of this application. The specific implementation methods of this application will be described below with reference to the accompanying drawings.

[0032] First, multiple lead-out terminals 3 are connectors fixedly mounted on the surface of the circuit board 1, and multiple windings 2 are led outward through the connectors to be electrically connected to other components.

[0033] By using a surface-mount connector on the board 1 as the lead-out terminal 3, a low-cost and easy-to-implement electrical connection solution is provided. Since the connector is directly fixed to the board surface and connected via flying wires, the manufacturing process is simplified, reducing manufacturing costs. At the same time, this external connection method provides flexibility for winding lead-out, avoiding complex on-board interconnection designs. While ensuring connection reliability, it is particularly suitable for cost-sensitive applications with limited installation space requirements.

[0034] Specifically, such as Figures 4-5 As shown, the plurality of windings 2 include a first winding 21 and a second winding 22; the first winding 21 is disposed on the first circuit board 11; the second winding 22 is disposed on the second circuit board 12; The plurality of lead-out terminals 3 include a first connector 41 and a second connector 42; the first connector 41 is electrically connected to the first winding 21 for leading out the first winding 21 and for being electrically connected to other components; the second connector 42 is electrically connected to the second winding 22 for leading out the second winding 22 and for being electrically connected to other components.

[0035] This scheme explicitly associates a specific winding 2 with the corresponding circuit board 1 and connectors, achieving optimal matching between electrical and physical structures. By setting the first winding 21 and the second winding 22 on the two sides of the circuit board 1 respectively and using their own independent connectors to lead them out, the electrical paths of the two windings are completely isolated, greatly enhancing the system's isolation withstand voltage capability.

[0036] It should be noted that the specific types of the first winding 21 and the second winding 22 are not limited. In one possible implementation, one of the first winding 21 and the second winding 22 is the primary winding, and the other is the secondary winding. Thus, the first winding 21 and the second winding 22 together constitute a complete planar transformer. In another possible implementation, the first winding 21 and the second winding 22 can together constitute the primary winding of the planar transformer. Exemplarily, the secondary winding of the planar transformer can be disposed on a circuit board located inside the two side circuit boards 1. Those skilled in the art can design the cooperation relationship between the first winding 21, the second winding 22, and the third winding 23 (the arrangement of the third winding 23 will be described in detail later) as needed, and this application does not impose any restrictions here.

[0037] The above is a description of the connector solution provided in this application. However, this solution requires the winding to be set on the first circuit board 11 and the second circuit board 12, and its application scenarios are relatively limited.

[0038] Therefore, this application also provides a blind hole solution, which does not restrict the design position of the winding and has a wider range of applications.

[0039] Please see Figure 6 A front view structural schematic diagram of another implementation of a planar transformer for this application; Figure 7 A schematic diagram of the projected area of ​​another implementation of the planar transformer for this application; Figure 8 A front view structural schematic diagram of another implementation of a planar transformer for this application; Figure 9 This provides a schematic diagram of the projected area for another implementation of a planar transformer in this application.

[0040] like Figures 6-9 As shown, in one possible implementation, multiple lead-out terminals 3 are blind holes, and the walls of the blind holes are electroplated to achieve electrical connection; the blind holes are located at the center of the winding 2. By using blind holes as lead-out terminals 3, the electrical connection point is transferred from the board surface to the inside of the board, which can ignore the winding position restriction and also avoid the creepage distance restriction, thereby reducing the space occupied by the planar transformer 100.

[0041] Specifically, such as Figures 6-7 As shown, in another possible implementation, when the plurality of windings 2 include a first winding 21 and a second winding 22, the first winding 21 and the second winding 22 are arranged at a relative interval in the first direction z, and the first winding 21 is arranged on the side closer to the first circuit board 11, and the second winding 22 is arranged on the side closer to the second circuit board 12. The blind vias include a first blind via 51 and a second blind via 52; one end of the first blind via 51 is electrically connected to the first winding 21, and the other end extends to the surface of the first circuit board 11; one end of the second blind via 52 is electrically connected to the second winding 22, and the other end extends to the surface of the second circuit board 12.

[0042] This design optimizes the layout of the dual-winding 2 structure. By placing the two windings close to the two side circuit boards 1 and using blind vias drilled from their respective adjacent sides, optimal safety and space utilization are achieved. Since the two blind via openings are located on opposite sides of the PCB, there is no need to consider safety distances on a single plane. Therefore, the two windings can be as close as possible, even partially overlapping, in the projection direction. This significantly reduces the required board area for the transformer.

[0043] Similarly, such as Figures 8-9 As shown, in another possible implementation, the plurality of windings 2 include a first winding 21, a second winding 22 and a third winding 23; the first winding 21 and the second winding 22 are disposed on the side closer to the first circuit board 11; the third winding 23 is disposed on the side closer to the second circuit board 12. The blind vias include a first blind via 51, a second blind via 52, and a third blind via 53; one end of the first blind via 51 is electrically connected to the first winding 21, and the other end extends to the surface of the first circuit board 11; one end of the second blind via 52 is electrically connected to the second winding 22, and the other end extends to the surface of the first circuit board 11; one end of the third blind via 53 is electrically connected to the third winding 23, and the other end extends to the surface of the second circuit board 12.

[0044] This can be understood as follows: the blind via solution is also applicable to more complex scenarios with three windings 2. By concentrating the blind vias of two windings and bringing them out from one side, and bringing the blind via of the third winding out from the other side, the conflict between multiple outputs and space constraints is balanced. Although this layout requires safety clearance for the two blind vias on one side of the circuit board 1, by placing the third winding entirely on the other side, it is still significantly superior to the traditional design where all winding leads 3 are on the same side. It provides a reliable solution that effectively controls the board area even under the requirement of multiple isolated outputs.

[0045] The above are examples illustrating specific implementation methods of the three lead-out terminals 3 and related structures of the planar transformer 100 provided in this application. The structure of each component will be described below.

[0046] In one possible implementation, the depth and diameter of the blind via are in a 1:1 ratio. This ensures the uniformity and continuity of the coating on the via wall, avoiding quality problems such as coating voids and breaks, thereby improving product yield and long-term reliability.

[0047] In one possible implementation, the planar transformer 100 is used in an electrical control system operating at 800V or higher; the distance between the first blind via 51 and the second blind via 52 on a plane perpendicular to the first direction z is greater than or equal to 4.5mm. This ensures that, despite its small size, the industry safety standards for surface creepage distance are strictly met at high operating voltages of 800V or higher, thus guaranteeing safety performance.

[0048] Those skilled in the art will understand that the above description of the structure of the planar transformer 100 is merely illustrative, and the planar transformer 100 may include more or fewer structures to achieve specific functions, etc.

[0049] For example, in one possible implementation, the planar transformer 100 further includes a primary winding and a magnetic core; the magnetic core penetrates the multilayer circuit board 1 perpendicularly along a first direction z, and the primary winding is wound around the magnetic core. This solution, by introducing a magnetic core and a primary winding, constructs a complete and fully functional transformer while reducing the overall size of the transformer.

[0050] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A high-density planar transformer, characterized in that, The planar transformer includes a multilayer circuit board, multiple windings, and multiple lead-out terminals; The multilayer circuit board is arranged sequentially along a first direction, including a first circuit board and a second circuit board; the first circuit board and the second circuit board are located on the outermost side of the multilayer circuit board and are arranged opposite to each other in the first direction; Each of the plurality of windings is disposed on a different layer of the multilayer circuit board; The plurality of lead-out terminals are arranged one-to-one with the plurality of windings, and one end is electrically connected to the winding, while the other end is used for electrical connection with other components; at least two of the plurality of lead-out terminals are respectively arranged on both sides of the multilayer circuit board in the first direction.

2. The planar transformer as described in claim 1, characterized in that, The plurality of lead-out terminals are connectors fixedly mounted on the surface of the circuit board, and the plurality of windings are led outward through the connectors to be electrically connected to other components.

3. The planar transformer as described in claim 2, characterized in that, The plurality of windings includes a first winding and a second winding; the first winding is disposed on the first circuit board; the second winding is disposed on the second circuit board; The plurality of lead-out terminals include a first connector and a second connector; the first connector is electrically connected to the first winding for leading out the first winding and is electrically connected to other components; the second connector is electrically connected to the second winding for leading out the second winding and is electrically connected to other components. One of the first winding and the second winding is the primary winding, and the other winding is the secondary winding; or, the first winding and the second winding together constitute the primary winding of the planar transformer.

4. The planar transformer as described in claim 1, characterized in that, The plurality of lead-out terminals are blind holes, and the walls of the blind holes are electroplated to achieve electrical connection; the blind holes are located at the center of the winding.

5. The planar transformer as described in claim 4, characterized in that, The plurality of windings includes a first winding and a second winding, the first winding and the second winding are arranged at a distance from each other in the first direction, and the first winding is arranged on the side closer to the first circuit board, and the second winding is arranged on the side closer to the second circuit board. The blind via includes a first blind via and a second blind via; one end of the first blind via is electrically connected to the first winding, and the other end extends to the surface of the first circuit board; one end of the second blind via is electrically connected to the second winding, and the other end extends to the surface of the second circuit board.

6. The planar transformer as described in claim 5, characterized in that, The plurality of windings includes a first winding, a second winding, and a third winding; the first winding and the second winding are disposed near the first circuit board; the third winding is disposed near the second circuit board. The blind via includes a first blind via, a second blind via, and a third blind via; one end of the first blind via is electrically connected to the first winding, and the other end extends to the surface of the first circuit board; one end of the second blind via is electrically connected to the second winding, and the other end extends to the surface of the first circuit board; One end of the third blind hole is electrically connected to the third winding, and the other end extends to the surface of the second circuit board.

7. The planar transformer as described in claim 4, characterized in that, The ratio of the depth to the diameter of the blind hole is 1:

1.

8. The planar transformer as described in claim 6, characterized in that, The planar transformer is used in electrical control systems above 800V; the distance between the first blind hole and the second blind hole on a plane perpendicular to the first direction is greater than or equal to 4.5mm.

9. The planar transformer as described in claim 1, characterized in that, The planar transformer further includes a primary winding and a magnetic core; the magnetic core penetrates the multilayer circuit board perpendicularly along the first direction, and the primary winding is wound around the magnetic core.

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