Planar transformer and coil structure thereof

Abstract

The utility model discloses a planar transformer and a coil structure thereof, the coil structure comprises multiple layers of flexible printed circuit boards, and the multiple layers of flexible printed circuit boards are mutually connected through connecting parts formed by folding. Each layer of flexible printed circuit board comprises a flexible printed circuit board substrate, a first wire printed on a first surface of the flexible printed circuit board substrate and a second wire printed on a second surface of the flexible printed circuit board substrate, and the first wires of the multiple layers of flexible printed circuit boards are the same wire. The second wires of the multi-layer flexible printed circuit board are the same wire, so that interlayer interconnection of the multi-layer flexible printed circuit board can be realized without punching, and the manufacturing process of the coil structure is simplified.

Description

TECHNICAL FIELD

[0001] The utility model relates to planar transformer technical field, especially a planar transformer and coil structure thereof. BACKGROUND

[0002] The planar transformer is a new ferrite inductance element, and is a main product for realizing light, thin, small and miniaturized electronic products. Compared with the conventional transformer, the planar transformer not only has structural advantages, but also has the advantages of high power density, high efficiency, low leakage, good heat dissipation and low cost.

[0003] The traditional planar transformer is made by using the printed circuit board (PCB) process, and if the coil is made by using the planar winding, the more the single-layer conductor coil numbers are, the lower the utilization rate is. If the multi-layer conductor is used, the more the layers are, the higher the requirement for the positions of the coils of different layers is, and the greater the difficulty of manufacturing is. In order to solve the above problems, the prior art uses the PCB process to make the coil, and realizes the interconnection between the layers by pressing and increasing the via. The different winding layers are isolated by using the material with good insulation performance, so as to meet the voltage withstand grade requirement. However, this method needs to increase the via, and the process is relatively complex.

[0004] Therefore, a new planar transformer and coil structure need to be provided to solve the above problems. UTILITY MODEL CONTENTS

[0005] In view of the above problems, the utility model aims to provide a planar transformer and coil structure, so as to simplify the manufacturing process of the coil structure.

[0006] According to one aspect of the utility model, a coil structure is provided, which comprises a plurality of layers of flexible printed circuit boards, the plurality of layers of flexible printed circuit boards are connected to each other through a connection part formed by folding, each layer of the flexible printed circuit board comprises a flexible printed circuit board substrate, a first conductor printed on a first surface of the flexible printed circuit board substrate, and a second conductor printed on a second surface of the flexible printed circuit board substrate, the first conductors of the plurality of layers of flexible printed circuit boards are the same conductor, and the second conductors of the plurality of layers of flexible printed circuit boards are the same conductor.

[0007] Optionally, the size of each layer of the flexible printed circuit board is the same, the first conductors of the odd layers of the plurality of layers of flexible printed circuit boards overlap and the second conductors also overlap, and the first conductors of the even layers of the plurality of layers of flexible printed circuit boards overlap and the second conductors also overlap.

[0008] Optionally, the first conductor and the second conductor of each layer of the flexible printed circuit board comprise a first segment conductor extending in a first direction, a second segment conductor extending in a second direction, and a third segment conductor extending in the first direction, the length of the first segment conductor being greater than the length of the third segment conductor, and the first segment conductor and the third segment conductor are connected by the second segment conductor; for the flexible printed circuit board having two adjacent flexible printed circuit boards, the first segment conductor of the first conductor of the flexible printed circuit board is connected to the third segment conductor of the first conductor of one adjacent flexible printed circuit board, the third segment conductor of the first conductor of the flexible printed circuit board is connected to the first segment conductor of the first conductor of another adjacent flexible printed circuit board, the third segment conductor of the second conductor of the flexible printed circuit board is connected to the first segment conductor of the second conductor of the one adjacent flexible printed circuit board, and the first segment conductor of the second conductor of the flexible printed circuit board is connected to the third segment conductor of the second conductor of the another adjacent flexible printed circuit board; the second segment conductor of the first conductor of the same flexible printed circuit board is close to one edge of the flexible printed circuit board substrate parallel to the second segment conductor, and the second segment conductor of the second conductor is close to the other edge of the flexible printed circuit board substrate parallel to the second segment conductor.

[0009] Optionally, the first surface and the second surface of the flexible printed circuit board substrate are respectively covered with an insulating layer, and the first conductor and the second conductor are respectively covered with an insulating film.

[0010] Optionally, the two adjacent flexible printed circuit boards are bonded by the insulating film.

[0011] Optionally, for each layer of the flexible printed circuit board, the first conductor of the first surface and the second conductor of the second surface are staggered at the folding position.

[0012] Optionally, the multi-layer flexible printed circuit board is obtained by folding a mother flexible printed circuit board in a Z-shaped folding manner; for the flexible printed circuit board having two adjacent flexible printed circuit boards, the first surface of the flexible printed circuit board is arranged opposite to the first surface of one adjacent flexible printed circuit board, and the second surface of the flexible printed circuit board is arranged opposite to the second surface of another adjacent flexible printed circuit board.

[0013] Optionally, a through hole is arranged on each layer of the flexible printed circuit board, and the through holes of the multi-layer flexible printed circuit board are overlapped.

[0014] Optionally, the through hole is arranged at the middle position of each layer of the flexible printed circuit board.

[0015] According to another aspect of the present application, a planar transformer is provided, comprising the coil structure as described above, a magnetic core middle column passing through the through hole, and upper and lower iron cores connected to two ends of the magnetic core middle column, respectively.

[0016] The planar transformer and the coil structure thereof provided by the utility model, the coil structure comprises a plurality of layers of flexible printed circuit boards, the plurality of layers of flexible printed circuit boards are connected with each other through the connecting portions formed by folding, each layer of flexible printed circuit board comprises a flexible printed circuit board substrate, a first conductor printed on the first surface (front surface) of the flexible printed circuit board substrate and a second conductor printed on the second surface (back surface) of the flexible printed circuit board substrate, the first conductors of the plurality of layers of flexible printed circuit boards are the same conductor, and the second conductors of the plurality of layers of flexible printed circuit boards are the same conductor, so that the interlayer interconnection of the plurality of layers of flexible printed circuit boards can be realized without punching, and the manufacturing process of the coil structure is simplified. BRIEF DESCRIPTION OF DRAWINGS

[0017] The above and other objects, features and advantages of the present utility model will become more apparent from the following description of the utility model embodiments referring to the accompanying drawings. In the drawings:

[0018] Figure 1 A schematic view of a mother flexible printed circuit board according to an embodiment of the present utility model is shown;

[0019] Figure 2 A schematic view of a mother flexible printed circuit board when being folded according to an embodiment of the present utility model is shown;

[0020] Figure 3 A schematic view of a coil structure according to an embodiment of the present utility model is shown;

[0021] Figure 4 A layout schematic view of a plurality of coil structures that have not been folded in a processing process according to an embodiment of the present utility model is shown;

[0022] Figure 5 A schematic view of the plurality of coil structures after being folded is shown; Figure 4

[0023] Figure 6 A finished product schematic view of a single coil structure according to an embodiment of the present utility model is shown. DETAILED DESCRIPTION

[0024] Various embodiments of the present utility model will be described in more detail below with reference to the accompanying drawings. In each drawing, the same or similar elements or modules are denoted by the same or similar reference numerals. For the sake of clarity, each part in the drawings is not drawn in proportion.

[0025] ​It should be understood that in the following description, "circuitry" can include a single or multiple components of hardware, programmable circuitry, state machine circuitry, and / or elements that store instructions for execution by programmable circuitry. When an element or circuitry is referred to as being "connected to" another element or "between" two nodes, it can be directly coupled or connected to the other element or it can be present in intermediate elements, the connection between elements can be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled to" or "directly connected to" another element, it implies that there are no intermediate elements present.

[0026] Also, certain terminology can also be used in the present patent specification and claim in order to describe certain aspects of this application. It should be understood that a hardware manufacturer can use different terminology to refer to a same component. The present patent specification and claims do not distinguish components based on the name used by the manufacturer, but rather the function of the component.

[0027] In addition, it should also be noted that the terminology "first" and "second" and the like are used herein merely to distinguish one element from another, and do not necessarily limit the scope of each of the elements. Moreover, the terms "including", "comprising" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus that comprises a list of elements does not include only those elements recited, but can also include other elements not expressly listed or inherent to such process, method, article or apparatus. Without further limitation, an element defined by an expression "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0028] Referring to Figure 3 The coil structure 100 provided by the embodiment of the present application is realized by using a flexible printed circuit board (FPCB).

[0029] The coil structure 100 comprises a plurality of layers of flexible printed circuit boards (FPCB) 120a, and the plurality of layers of flexible printed circuit boards 120a are connected to each other through connection portions formed by folding. The adjacent layers of flexible printed circuit boards 120a are folded through at least one crease, and are connected through the connection portions formed by the crease after folding. It can be understood that, although Figure 3 Only six layers of flexible printed circuit boards 120a are shown, but the number of layers of the plurality of layers of flexible printed circuit boards 120a is not limited in the actual application.

[0030] Each flexible printed circuit board 120a comprises a flexible printed circuit board substrate 110a, a first conductor 111a printed on a first surface (front surface) of the flexible printed circuit board substrate 110a, and a second conductor 112a printed on a second surface (back surface) of the flexible printed circuit board substrate 110a. The first conductors 111a of the multi-layer flexible printed circuit board 120a are the same conductor, and the second conductors 112a of the multi-layer flexible printed circuit board 120a are the same conductor. The first surface and the second surface of the flexible printed circuit board substrate 110a are both covered with an insulating layer, which uses a material with good insulating properties as the main insulating layer. Since the flexible printed circuit board 120a itself has good insulating properties, and the first conductor 111a and the second conductor 112a are distributed on both sides of the flexible printed circuit board 120a, the coil structure 100 can meet the voltage resistance level requirements.

[0031] Optionally, the first conductor 111a and the second conductor 112a are both covered with an insulating film, such as an insulating adhesive film. When the insulating film covering the first conductor 111a and the second conductor 112a is an insulating adhesive film, the adjacent two flexible printed circuit boards 120a are bonded by the insulating film, so that the insulating film can not only achieve the insulating function of the first conductor 111a and the second conductor 112a, but also play a bonding role when folded.

[0032] Optionally, each flexible printed circuit board 120a is provided with a through hole 130, which is arranged away from the first conductor 111a and the second conductor 112a, and the through holes 130 of the multi-layer flexible printed circuit board 120a overlap. For example, the through holes 130 can be arranged at the middle position of each flexible printed circuit board 120a.

[0033] Optionally, for each flexible printed circuit board 120a, the first conductor 111a and the second conductor 112a are staggered with each other at the folding position to prevent the insulating properties of the flexible circuit board substrate 110a from being reduced due to folding.

[0034] Optionally, each flexible printed circuit board 120a has the same size, the first conductors 111a of the odd-numbered flexible printed circuit boards 120a of the multi-layer flexible printed circuit board 120a overlap and the second conductors 112a also overlap, and the first conductors 111a of the even-numbered flexible printed circuit boards 120a of the multi-layer flexible printed circuit board 120a overlap and the second conductors 112a also overlap.

[0035] Optionally, the first conductor 111a and the second conductor 112a of each flexible printed circuit board 120a comprise a first segment conductor extending in a first direction (e.g. transversely), a second segment conductor extending in a second direction (e.g. longitudinally), and a third segment conductor extending in the first direction, wherein the length of the first segment conductor is greater than the length of the third segment conductor, and the first segment conductor is connected to the third segment conductor by the second segment conductor; for the flexible printed circuit board 120a having two adjacent flexible printed circuit boards 120a, the first segment conductor of the first conductor 111a of the flexible printed circuit board 120a is connected to the third segment conductor of the first conductor 111a of one adjacent flexible printed circuit board 120a, the third segment conductor of the first conductor 111a of the flexible printed circuit board 120a is connected to the first segment conductor of the first conductor 111a of the other adjacent flexible printed circuit board 120a, the first segment conductor of the second conductor 112a of the flexible printed circuit board 120a is connected to the third segment conductor of the second conductor 112a of one adjacent flexible printed circuit board 120a, and the third segment conductor of the second conductor 112a of the flexible printed circuit board 120a is connected to the first segment conductor of the second conductor 112a of the other adjacent flexible printed circuit board 120a; the second segment conductor of the first conductor 111a of the same flexible printed circuit board 120a is close to one edge of the flexible printed circuit board substrate 110a parallel to the second segment conductor, and the second segment conductor of the second conductor 112a is close to the other edge of the flexible printed circuit board substrate 110a parallel to the second segment conductor, i.e. when the first direction is transverse, if the second segment conductor of the first conductor 111a is close to the left edge of the flexible printed circuit board substrate 110a, the second segment conductor of the second conductor 112a is close to the right edge of the flexible printed circuit board substrate 110a. Figure 1 For example, the first conductor 111a of the second flexible printed circuit board 120a in the coil structure 100 (multi-layer flexible printed circuit board 120a) comprises a first segment conductor 111b, a second segment conductor 111d, and a third segment conductor 111c.

[0036] Optionally, the coil structure 100 (multi-layer flexible printed circuit board 120a) is obtained by folding and pressing the mother flexible printed circuit board 120. For the flexible printed circuit board 120a having two adjacent flexible printed circuit boards 120a, the first surface of the flexible printed circuit board 120a is arranged opposite to the first surface of one adjacent flexible printed circuit board 120a, and the second surface of the flexible printed circuit board 120a is arranged opposite to the second surface of the other adjacent flexible printed circuit board 120a. The mother flexible printed circuit board 120 can be regarded as a mother flexible printed circuit board substrate 110 on which a mother first conductor 111 and a mother second conductor 112 are printed. Since the mother flexible printed circuit board substrate 110 is folded after the mother first conductor 111 and the mother second conductor 112 are printed, the first conductor 111a of the multi-layer flexible printed circuit board 120a can be the same conductor, and the second conductor 112a of the multi-layer flexible printed circuit board 120a can also be the same conductor, so that the interlayer connection of the multi-layer flexible printed circuit board 120a can be achieved without punching, and the manufacturing process of the coil structure is simplified.

[0037] Optionally, the through hole 130 is formed before the female flexible printed circuit board 120 is folded. Forming the through hole 130 before the female flexible printed circuit board 120 is folded can make the positioning of the through hole 130 accurate, thereby ensuring that there is sufficient insulation distance between the magnetic core and the first conductive wire 111a and the second conductive wire 112a when the coil structure 100 is applied to a planar transformer.

[0038] The coil structure 100 shown in the example can be obtained by Figure 3 The coil structure 100 shown in the example can be obtained by Figure 1 The female flexible printed circuit board 120 shown in the example is folded and laminated in the manner shown. Figure 2 The coil structure 100 shown in the example can be obtained by

[0039] Referring to Figure 1 , the first surface (front surface) of the female flexible printed circuit board substrate 110 is printed with the female first conductive wire 111, and the second surface (back surface) is printed with the female second conductive wire 112. Since the female flexible printed circuit board substrate 110 is gray, the female first conductive wire 111 appears black and the female second conductive wire 112 appears gray from the perspective shown in the figure. Figure 1

[0040] In Figure 1 , the female flexible printed circuit board substrate 110 has a plurality of folding lines 140, and the female flexible printed circuit board 120 is folded at the positions where the folding lines 140 are located. The folding lines 140 can be a line drawn on the female flexible printed circuit board substrate 110 and / or the insulating layer on the surface thereof, which does not damage the connection between the first conductive wire 111a and the second conductive wire 112a between adjacent layers of the female flexible printed circuit board 120a. The folding lines 140 are used to assist the folding of the female flexible printed circuit board 120 to ensure that the size of each layer of the female flexible printed circuit board 120a after folding is the same.

[0041] In Figure 1 , the female flexible printed circuit board 120 is designed to be folded in a Z-shaped folding manner, i.e. folded according to the inner folding and outer folding positions shown in Figure 1

[0042] It can be understood that although the present application only shows one folding method, the present application is not limited thereto, and other folding methods can also be used, such as double-width folding, folding, etc. When different folding methods are used, the female first conductive wire 111 and the female second conductive wire 112 on the female flexible printed circuit board substrate 110 can be designed according to the folding method. Among them, folding refers to folding the female flexible printed circuit board 120, then folding again, and so on until the desired number of layers of the female flexible printed circuit board 120a are obtained. Figure 3 ​​The coil structure 100 shown in the figure; the double-width folding refers to folding two ends of the female flexible printed circuit board 120 to the middle part, and then folding again, repeating the above steps until all layers of the first conductive wire 111a and the second conductive wire 112a are overlapped respectively, until the Figure 3 The coil structure 100 shown in the figure.

[0043] It can be understood that in the above content, the female flexible printed circuit board 120 refers to an entire piece of flexible printed circuit board without folding, the female flexible printed circuit board substrate 110 refers to an entire piece of flexible printed circuit board substrate without folding, the female first conductive wire 111 refers to an entire first conductive wire without folding, and the female second conductive wire 112 refers to an entire second conductive wire 112 without folding. The flexible printed circuit board 120a refers to the flexible printed circuit board of each layer before or after folding, the flexible printed circuit board substrate 110a refers to the flexible printed circuit board substrate of each layer before or after folding, the first conductive wire 111a refers to the first conductive wire of each layer before or after folding, and the second conductive wire 112a refers to the second conductive wire of each layer before or after folding.

[0044] In the actual processing process, a plurality of coil structures 100 can be simultaneously manufactured on the same flexible printed circuit board substrate. Referring to the dashed box in Figure 4 , Figure 4 , it indicates an un-folded coil structure 100. Folding the flexible printed circuit board substrate shown in Figure 4 can form a plurality of coil structures 100 as shown in Figure 5 . Finally, cutting the plurality of coil structures 100 shown in Figure 5 can obtain a single coil structure 100 as shown in Figure 6 .

[0045] It can be understood that the utility model also provides a planar transformer, including the coil structure 100 and the magnetic core as described above, the magnetic core includes the magnetic core middle column passing through the through hole 130, and the upper iron and the lower iron are connected with both ends of the magnetic core middle column respectively.

[0046] The planar transformer and the coil structure thereof provided by the utility model embodiment, the coil structure includes a plurality of layers of flexible printed circuit boards, the plurality of layers of flexible printed circuit boards are connected with each other through the connecting part formed by folding, each layer of flexible printed circuit board includes a flexible printed circuit board substrate, a first conductive wire printed on the first surface (front surface) of the flexible printed circuit board substrate, and a second conductive wire printed on the second surface (back surface) of the flexible printed circuit board substrate, the first conductive wire of the plurality of layers of flexible printed circuit boards is the same conductive wire, and the second conductive wire of the plurality of layers of flexible printed circuit boards is the same conductive wire, so that the interlayer interconnection between the plurality of layers of flexible printed circuit boards can be realized without punching, and the manufacturing process of the coil structure is simplified.

[0047] In accordance with the embodiments of the present application as described above, these embodiments do not describe all the details, nor limit the present application to only the specific embodiments. Obviously, according to the above description, many modifications and changes can be made. The present application selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well utilize the present application and make modifications on the basis of the present application. The protection scope of the present application should be limited by the scope defined by the claims of the present application and their equivalents.

Claims

1. A coil structure, characterized by, The application relates to a multi-layer flexible printed circuit board, which is connected with each other through a connecting part formed by folding, each layer of the flexible printed circuit board comprises a flexible printed circuit board substrate, a first conductor printed on a first surface of the flexible printed circuit board substrate and a second conductor printed on a second surface of the flexible printed circuit board substrate, the first conductors of the multi-layer flexible printed circuit board are the same conductor, and the second conductors of the multi-layer flexible printed circuit board are the same conductor. The size of each layer of the flexible printed circuit board is the same, the first conductors of odd-numbered layers of the flexible printed circuit board of the multi-layer flexible printed circuit board are overlapped and the second conductors are also overlapped, and the first conductors of even-numbered layers of the flexible printed circuit board of the multi-layer flexible printed circuit board are overlapped and the second conductors are also overlapped.

2. The coil structure of claim 1, wherein, The first conductor and the second conductor of each layer of the flexible printed circuit board comprise a first section of conductor extending along a first direction, a second section of conductor extending along a second direction and a third section of conductor extending along the first direction, the length of the first section of conductor is greater than the length of the third section of conductor, and the first section of conductor is connected with the third section of conductor through the second section of conductor.

3. The coil structure of claim 1, wherein, For the flexible printed circuit board with two adjacent flexible printed circuit boards, the first section of conductor of the first conductor is connected with the third section of conductor of the first conductor of one adjacent flexible printed circuit board, the third section of conductor of the first conductor is connected with the first section of conductor of the first conductor of the other adjacent flexible printed circuit board, the third section of conductor of the second conductor is connected with the first section of conductor of the second conductor of the one adjacent flexible printed circuit board, and the first section of conductor of the second conductor is connected with the third section of conductor of the second conductor of the other adjacent flexible printed circuit board. The second section of conductor of the first conductor of the same flexible printed circuit board is close to one edge of the flexible printed circuit board substrate parallel to the second section of conductor, and the second section of conductor of the second conductor is close to the other edge of the flexible printed circuit board substrate parallel to the second section of conductor. The first surface and the second surface of the flexible printed circuit board substrate are respectively covered with an insulating layer, and the first conductor and the second conductor are both covered with an insulating film.

4. The coil structure of claim 1, wherein, The two adjacent flexible printed circuit boards are bonded through the insulating film.

5. The coil structure of claim 4, wherein, For each layer of the flexible printed circuit board, the first conductor of the first surface and the second conductor of the second surface are staggered at the folding position.

6. The coil structure of claim 1, wherein, The multi-layer flexible printed circuit board is folded in a Z-shaped folding mode by a mother flexible printed circuit board.

7. The coil structure of claim 1, wherein, For the flexible printed circuit board with two adjacent flexible printed circuit boards, the first surface is oppositely arranged with the first surface of one adjacent flexible printed circuit board, and the second surface is oppositely arranged with the second surface of the other adjacent flexible printed circuit board. A through hole is arranged on each layer of the flexible printed circuit board, and the through holes of the multi-layer flexible printed circuit board are overlapped.

8. The coil structure according to any one of claims 1 to 7, characterized in that The through hole is arranged at a middle position of each layer of the flexible printed circuit board.

9. The coil structure of claim 8, wherein, The application relates to a coil structure as claimed in any one of claims 8 or 9; 10. A planar transformer, characterized by A magnetic core middle column passes through the through hole; and Upper and lower iron cores are respectively connected with two ends of the magnetic core middle column. ​ ​ ​

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