Transformer comprising a printed circuit board and method of manufacturing the same

Abstract

A transformer including a printed circuit board and a manufacturing method thereof are provided. A transformer includes a core portion having magnetism and having a through hole formed therein, and a first coil portion formed with a first circuit board on one surface of which a circuit pattern is printed, the first coil portion having a shape that surrounds a portion of the core portion while penetrating the through hole of the core portion and being formed to be bent so that both side end portions of the first circuit board are connected to each other.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a transformer including a printed circuit board and a manufacturing method thereof, and more particularly, to a three-dimensional transformer formed by bending a planar printed circuit board. BACKGROUND

[0002] A transformer is a device for further increasing or decreasing an alternating voltage based on the principle of electromagnetic induction. Two primary and secondary coils are wound around a magnetic core, and when an alternating voltage is applied to the primary coil, a change in magnetic flux due to an alternating current occurs, which in turn induces an electromotive force in the secondary coil. The magnitude of the electromotive force induced in the secondary coil has the following relationship with the number of turns of the coil.

[0003] V2 / V1=N2 / N1

[0004] In this context, V1 refers to the power supply voltage of the primary coil, V2 refers to the induced electromotive force of the secondary coil, N1 refers to the number of turns of the primary coil, and N2 refers to the number of turns of the secondary coil.

[0005] Therefore, when it is desired to increase the voltage, the number of turns of the secondary coil can be set to be greater than the number of turns of the primary coil. In this context, since energy is conserved when heat loss is ignored, the power input to the primary coil is equal to the power output to the secondary coil.

[0006] In such a transformer, the primary and secondary coils surround a portion of the magnetic core, and in order to form the primary and secondary coils, the coils must be wound around the magnetic core.

[0007] However, there is a problem in that the winding work requires expensive winding equipment and skilled techniques, and it takes a lot of effort and time to perform this work. In addition, there is a problem of bulk expansion due to the end turns of the coil turns, and various problems such as short circuits, edges, or vibrations caused in the coil turns have occurred.

[0008] In order to solve these problems, a transformer using a printed circuit board (PCB) has been developed, but a planar transformer using such a printed circuit board has a problem in that sufficient transformer capacity cannot be obtained.

[0009] The above is merely intended to help understand the background of the present disclosure, and is not intended to mean that the present disclosure falls within the scope of the related art known to those skilled in the art. SUMMARY

[0010] The present disclosure provides a three-dimensional transformer and a method of manufacturing a transformer formed by bending a planar printed circuit board on which a circuit pattern is printed to surround a magnetic core.

[0011] A transformer according to the present disclosure includes a magnetic core portion having magnetism and having a through-hole formed therein, and a first coil portion formed with a first circuit board on one surface of which a circuit pattern is printed, the first coil portion having a shape that surrounds a portion of the magnetic core portion while penetrating the through-hole of the magnetic core portion and being curved so that side end portions (i.e., both side end portions) of the first circuit board are connected to each other.

[0012] The first coil portion can be connected to the side end portions of the first circuit board so that the printed circuit pattern of the first circuit board is continuous.

[0013] The transformer can further include connectors coupled to the side end portions of the first circuit board, respectively, by soldering to connect the printed circuit pattern on the first circuit board.

[0014] The first coil portion can include a second circuit board connected between the side end portions of the first circuit board so that a circuit pattern printed on one surface thereof is continuous with the circuit pattern of the first circuit board.

[0015] The first coil portion can include a connector disposed between the second circuit board and the side end portions of the first circuit board to connect a circuit pattern printed on the second circuit board with the circuit pattern printed on the first circuit board.

[0016] The connector can be coupled to the first circuit board or the second circuit board by soldering.

[0017] The first coil portion can have a cutting line formed on the other surface of the first circuit board, in which a portion of the first circuit board is cut, and can be curved along the formed cutting line.

[0018] The first coil portion can be curved so that the other surface of the first circuit board on which the cutting line is formed forms an outer surface thereof, and one surface of the first circuit board on which the circuit pattern is printed can be located on an inner surface thereof.

[0019] The first coil portion can be curved so that the other surface of the first circuit board on which the cutting line is formed forms an inner surface thereof, and one surface of the first circuit board on which the circuit pattern is printed can be located on an outer surface thereof.

[0020] The transformer can further include a second coil portion formed with a first circuit board on one surface of which a circuit pattern is printed, the second coil portion having a shape that surrounds another portion of the magnetic core portion while penetrating the through-hole of the magnetic core portion and being curved so that side end portions of the first circuit board are connected to each other; and the number of circuit patterns printed on the first circuit boards that form the first coil portion and the second coil portion, respectively, can be different from each other.

[0021] The transformer can further include a second coil portion formed with a first circuit board on one surface of which a circuit pattern is printed, the second coil portion having a shape of surrounding another portion of the magnetic core portion while penetrating a through-hole of the magnetic core portion and being bent so that side end portions of the first circuit board are connected to each other, and the first coil portion and the second coil portion can be formed by stacking at least one first circuit board, and the number of the first circuit boards forming the first coil portion and the second coil portion, respectively, can be different from each other.

[0022] A method of manufacturing a transformer according to the disclosure includes printing a circuit pattern on one surface of a first circuit board, bending the first circuit board into a shape of surrounding a portion of a magnetic core portion having magnetism while the first circuit board penetrates a through-hole of the magnetic core portion, and forming a first coil portion by connecting side end portions of the first circuit board to each other.

[0023] The method can further include forming a cutting line cutting a portion of the first circuit board on another surface of the first circuit board before the bending, and the first circuit board can be bent along the cutting line when the bending.

[0024] The forming of the first coil portion can connect the side end portions of the first circuit board so that the circuit pattern printed on the first circuit board is continuous.

[0025] The forming of the first coil portion can connect a second circuit board on which a circuit pattern is printed between the side end portions of the first circuit board so as to be continuous with the circuit pattern printed on the first circuit board.

[0026] The method can further include connecting the circuit pattern printed on the first circuit board by coupling a connector to the side end portions of the first circuit board via soldering before the bending.

[0027] According to the transformer using a printed circuit board according to the disclosure and the method of manufacturing the same, there are effects that a winding device and skilled techniques are not necessary because a PCB pattern is used instead of a winding coil of a transformer, and the time required for production is shortened, thereby improving the productivity of the transformer.

[0028] In addition, there are effects of solving problems such as short circuit and edge of a coil caused in a coil winding process.

[0029] In addition, there are effects of eliminating a space occupied by an end turn of a wound coil, thereby reducing the volume of the transformer.

[0030] In addition, there are effects of being able to increase the capacity of the transformer compared to a transformer using a conventional flat PCB. BRIEF DESCRIPTION OF DRAWINGS

[0031] The above and other objects, features and other advantages of the present disclosure will more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0032] Figure 1 is an exploded perspective view of a transformer according to one embodiment of the present disclosure.

[0033] Figure 2 is a perspective view illustrating a state before bending a first circuit board forming a first coil portion according to one embodiment of the present disclosure.

[0034] Figure 3 and Figure 4 illustrates a cutting line and a bending direction according to one embodiment of the present disclosure.

[0035] Figure 5 is a perspective view of a transformer according to another embodiment of the present disclosure.

[0036] Figure 6 is a flowchart of a method of manufacturing a transformer according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0037] It should be understood that the term "vehicle" or "vehicular" or other similar terminology used herein includes a broad range of vehicles including passenger cars (including sport utility vehicles (SUVs), buses, trucks), various commercial vehicles, watercraft (including various types of boats and ships), aircraft, etc., and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., those that are powered by fuels other than petroleum). As used herein, a hybrid vehicle is one that has two or more sources of power, such as a gasoline-powered and electric-powered vehicle.

[0038] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. In the description, unless the context clearly indicates otherwise, the word "comprising" and variations such as "comprise" or "comprises" will not be construed as being limited to the enumerated members, but rather, will be construed to include the enumerated members and also any other member that is a logical extension of the enumerated members. In addition, the terms "unit", "device", "apparatus" and "module" described in the specification mean a unit for processing at least one function and operation, and can be implemented by hardware components or software components and combinations thereof.

[0039] Further, the control logic of the present disclosure can be embodied on a computer readable medium including executable program instructions, which are implemented by a processor, a controller, etc. Examples of the computer readable medium include, but are not limited to, ROM, RAM, compact disc (CD)-ROM, magnetic tapes, floppy disks, flash drives, smart cards, and optical data storage devices. The computer readable recording medium can also be distributed over network-coupled computer systems so that the computer readable medium is stored and implemented in a distributed fashion via, for example, a vehicle-mounted communication server or a controller area network (CAN).

[0040] Various modifications and various forms can be made in the embodiments according to the present disclosure, so that specific embodiments are illustrated in the drawings and described in detail in the specification or application. However, it should be understood that the embodiments according to the concepts of the present disclosure are not intended to be limited to the disclosed special forms, but include all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present disclosure.

[0041] The terms "first" and / or "second" and the like are used illustratively and are not intended to limit the components. These terms are used to distinguish one element from another, e.g., a first component can be termed a second component, and, likewise, a second component can also be termed a first component, without departing from the claims of the concepts according to the present disclosure.

[0042] It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be "directly connected" or "directly coupled" to the other element or intervening elements can be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other expressions that describe the relationship between elements should be interpreted in the like fashion (e.g., "between" versus "directly between", "adjacent" versus "directly adjacent", etc.).

[0043] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined in the specification.

[0044] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The same reference numerals in each drawing denote the same elements.

[0045] Figure 1 is an exploded perspective view of a transformer according to one embodiment of the present disclosure, and Figure 2 is a perspective view illustrating a state before bending a first circuit board 210 according to one embodiment of the present disclosure. As provided herein, the transformer includes a printed circuit board, which corresponds to the first circuit board and / or the second circuit board, as described herein.

[0046] Referring to Figure 1 and Figure 2 A transformer according to one embodiment of the present disclosure includes a magnetic core portion 100 having magnetism and having a through-hole 110 formed therein, and a first coil portion 200 formed with a first circuit board 210 on which a circuit pattern is printed on one surface, the first coil portion having a shape that surrounds a portion of the magnetic core portion 100 while penetrating the through-hole of the magnetic core portion 100, and being formed to be bent such that side end portions (i.e., both side end portions) of the first circuit board are connected to each other.

[0047] A transformer is used to increase or decrease an alternating voltage using an electromagnetic induction phenomenon. Accordingly, the first coil portion 200 is formed to surround a portion of the magnetic core portion 100. Generally, a transformer includes a primary coil and a secondary coil connected to an input side and an output side, respectively, and power is input to the input side and power is output to the output side. However, since only the number of turns of the coil between the primary coil and the secondary coil is different, and the technology of the present disclosure is equally applicable to them, only the first coil portion 200 will be described in detail, which is equally applicable to both the primary coil and the secondary coil, and also equally applicable to the second coil portion 300.

[0048] The magnetic core portion 100 (also called a core) is a passage for forming a magnetic path of magnetic lines. Accordingly, the magnetic core portion 100 is formed of a magnetic material, and in a high frequency circuit, a dust core can be used, which is compression-molded by using a magnetic material as a powder of an electrically insulating coating.

[0049] The core portion 100 can be various shapes, but in this embodiment, it is a cuboid shape having a through-hole 110 formed therein, and is explained as a shape that surrounds a portion of the magnetic core portion 100 while the first coil portion 200 penetrates the through-hole 110 of the magnetic core portion 100.

[0050] The first coil portion 200 is formed with a first circuit board 210 on one surface 211 of which a circuit pattern is printed. A plurality of circuit patterns can be printed on one surface 211 of the first circuit board 210. In particular, the circuit pattern can be a straight line-shaped circuit pattern extending from one side end portion thereof to the other side end portion thereof.

[0051] The first coil portion 200 can be a shape that surrounds a portion of the magnetic core portion 100 while penetrating the through-hole 110 of the magnetic core portion 100, and is formed to be bent so that both side end portions of the first circuit board 210 are connected to each other. As Figure 1 illustrated, for example, when a portion of the magnetic core portion 100 is a square pillar shape, the first circuit board 210 is bent three times to form the first coil portion 200, thereby surrounding a portion of the magnetic core portion 100. As illustrated, the bending angle can be 90°, but can also be formed in an acute angle of 90° or less, or in an obtuse angle of 90° or more, so that the number of bending times can be changed.

[0052] Accordingly, when the winding coil of the transformer is replaced with the PCB pattern, a winding device and skilled techniques are not necessary, and the time required for production is shortened, thereby improving the productivity of the transformer.

[0053] The first coil portion 200 can have both side end portions of the first circuit board 210 connected to each other such that the printed circuit pattern of the first circuit board 210 is continuous. That is, both side end portions of the first circuit board 210 can be connected such that the circuit pattern having a straight shape between both side end portions of the first circuit board 210 is connected to each other to form a coil on which the printed circuit pattern of the first circuit board 210 is continuous.

[0054] As one embodiment, both side end portions of the first circuit board 210 can be directly coupled to each other. That is, one side end portion of the first circuit board 210 and the other side end portion thereof can be coupled by soldering such that the circuit pattern of the first circuit board 210 can be continuous.

[0055] As another embodiment, the disclosure can further include a connector 230 coupled to both side end portions of the first circuit board 210 by soldering, respectively, to connect the printed circuit pattern on the first circuit board 210.

[0056] As still another embodiment, the first coil portion 200 can include a second circuit board 220 connected between both side end portions of the first circuit board 210 such that the circuit pattern printed on one surface of the second circuit board is continuous with the circuit pattern of the first circuit board 210. That is, the second circuit board 220 is further provided on which the circuit pattern is printed on one surface 211 like the first circuit board 210 such that the second circuit board 220 is coupled to both side end portions of the first circuit board 210, respectively, to continuously connect the circuit pattern of the first circuit board 210. In addition, the second circuit board 220 can also be used like this by the planar circuit board, and can be coupled to the first circuit board 210 in a bent state like the first circuit board 210.

[0057] The first coil portion 200 can include a connector 230 disposed between the second circuit board 220 and both side end portions of the first circuit board 210 to connect the circuit pattern printed on the second circuit board 220 with the circuit pattern printed on the first circuit board 210.

[0058] One end of the connector 230 is connected to the circuit pattern of the first circuit board 210 at both side end portions of the first circuit board 210, and the other end is coupled by soldering with the first circuit board 210 or the second circuit board 220 to be connected to the circuit pattern of the second circuit board 220. In addition, the connector 230 can be directly connected between both side end portions of the first circuit board 210 without the second circuit board 220.

[0059] Figure 3 and Figure 4A cutting line 213 and a bending direction according to one embodiment of the present disclosure are illustrated by way of example.

[0060] Further referring to Figures 3 to 4 , the first coil portion 200 has a cutting line 213 formed on the other surface of the first circuit board 210, cuts a portion of the first circuit board 210 on the cutting line 213, and can bend the first circuit board 210 along the formed cutting line 213.

[0061] The cutting line 213 can be formed on the other surface opposite to one surface of the first circuit board 210 on which a circuit pattern is printed by a cutting process such as milling, cuts a portion of the first circuit board 210 on the cutting line 213, and can bend the first circuit board 210 along the formed cutting line 213.

[0062] As shown in FIG. 1A, the first coil portion 200 can be bent such that the other surface 212 of the first circuit board 210 on which the cutting line 213 is formed forms an outer surface thereof. Figure 3 That is, the other surface 212 of the first circuit board 210 on which the cutting line 213 is formed forms an outer surface thereof such that one surface 211 of the first circuit board 210 on which a circuit pattern is printed can be located on an inner surface thereof.

[0063] On the contrary, as shown in FIG. 1B, the first coil portion 200 can be bent such that the other surface 212 of the first circuit board 210 on which the cutting line 213 is formed forms an inner surface thereof such that one surface 211 of the first circuit board 210 on which a circuit pattern is printed can be located on an outer surface thereof. Figure 4 That is, the cutting line 213 is formed on the other surface 212 opposite to one surface 211 of the first circuit board 210 on which a circuit pattern is printed, and the other surface 212 on which the cutting line 213 is formed is bent to become an outer surface of the first coil portion 200, or on the contrary, the other surface 212 on which the cutting line 213 is formed is bent to become an inner surface of the first coil portion 200. The cutting line 213 can be processed such that shapes of the cutting line 213 are different from each other along the bending direction.

[0064]

[0065] ​The transformer using a printed circuit board according to the embodiment of the disclosure can further include a second coil portion 300 formed with the first circuit board 210 on which a circuit pattern is printed on one surface 211 of the first circuit board 210, the second coil portion having a shape of surrounding another portion of the magnetic core portion 100 while penetrating the through-hole 110 of the magnetic core portion 100 and being curved so that both side end portions of the first circuit board 210 are connected to each other. The first coil portion 200 and the second coil portion 300 can be connected to a power input side or a power output side of the transformer, respectively.

[0066] The number of the circuit patterns printed on the first circuit board 210 forming the first coil portion 200 and the second coil portion 300, respectively, can be different from each other. Thus, when the number of turns of the coil of the first coil portion 200 and the number of turns of the coil of the second coil portion 300 are different, the voltage at the power input side and the voltage at the power output side are different, thereby performing a voltage transformation.

[0067] Figure 5 is a perspective view of a transformer according to another embodiment of the disclosure.

[0068] Reference Figure 5 The transformer using a printed circuit board can further include a second coil portion 300 formed with the first circuit board 210 on which a circuit pattern is printed on one surface 211 of the first circuit board 210, the second coil portion having a shape of surrounding another portion of the magnetic core portion 100 while penetrating the through-hole 110 of the magnetic core portion 100 and being curved so that both side end portions of the first circuit board 210 are connected to each other; the first coil portion 200 and the second coil portion 300 are formed by stacking at least one of the first circuit boards 210; and the number of the first circuit boards 210, 310 forming the first coil portion 200 and the second coil portion 300, respectively, can be different from each other.

[0069] That is, the first coil portion 200 and the second coil portion 300 connected to a power input side or a power output side of the transformer can be formed by stacking at least one of the same first circuit portion 210, 310. However, the number of the first circuit boards 210, 310 forming the first coil portion 200 and the second coil portion 300 can be different. Thus, the number of turns of the coil of the first coil portion 200 and the second coil portion 300 is different, so that the transformer can increase or decrease the voltage between the power input side and the power output side. That is, it is possible to form the first coil portion 200 and the second coil portion 300 using the same first circuit board 210, 310 so that the number of turns of the coil of the first coil portion 200 and the second coil portion 300 becomes different, thereby improving productivity.

[0070] In addition, the transformer can be simply changed in increasing or decreasing ratio by additionally assembling or disassembling the first circuit board 210, 310.

[0071] According to Figure 5 According to an embodiment of the present disclosure, since the ratio of the number of turns of the coil is 1:3, a transformer that can increase or decrease the voltage by 3 times or 1 / 3 can be formed.

[0072] Figure 6 is a flowchart of a method of manufacturing a transformer according to an embodiment of the present disclosure.

[0073] Referring to Figure 6 A method of manufacturing a transformer according to an embodiment of the present disclosure includes printing a circuit pattern on one surface of a first circuit board (S100), bending the first circuit board into a shape that surrounds a portion of a magnetic core part while the first circuit board penetrates a through-hole of the magnetic core part having magnetism (S400), and forming a first coil part by connecting two side end parts of the first circuit board to each other (S500).

[0074] Before the bending step (S400), the method can further include forming a cutting line that cuts a portion of the first circuit board on the other surface of the first circuit board (S200), and when bent (S400), the first circuit board can be bent along the cutting line.

[0075] When forming the first coil part (S500), the two side end parts of the first circuit board can be connected such that the printed circuit pattern on the first circuit board is continuous. At this time, the two side end parts of the first circuit board can be coupled to be directly connected to each other.

[0076] In addition, when forming the first coil part (S500), a second circuit board on which a circuit pattern is printed can be connected between the two side end parts of the first circuit board to be continuous with the printed circuit pattern on the first circuit board. That is, the second circuit board can be provided between the two side end parts of the first circuit board such that the two side end parts of the first circuit board are connected to the second circuit board, respectively.

[0077] Before the bending step (S400), the method can further include connecting a connector to the two side end parts of the first circuit board by soldering to be connected with the printed circuit pattern on the first circuit board.

[0078] The connector can also be coupled to the first circuit board while the first circuit board is bent, but can be coupled to the first circuit board before bending. When it is coupled to a flat first circuit board that is not bent by soldering, the soldering operation can be more convenient. The first circuit board in a bent state can flexibly change the bending angle on the bent portion to cause a gap therebetween, so that the soldering operation is not facilitated.

[0079] Hereinafter, the same description will be omitted as for the transformer using the printed circuit board.

[0080] While the present disclosure has been illustrated and described with respect to specific embodiments, it will be understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as disclosed in the following claims.

Claims

1. A transformer comprising: a core portion having magnetism and having a through-hole formed therein; and a first coil portion formed with a first circuit board on one surface of which a circuit pattern is printed, the first coil portion having a shape of surrounding a portion of the core portion while penetrating the through-hole of the core portion and being formed to be bent so that side end portions of the first circuit board are connected to each other; wherein the first coil portion has a cutting line on which a portion of the first circuit board is cut, the cutting line being formed on the other surface of the first circuit board, and the first circuit board is configured to be bent along the formed cutting line; wherein the first coil portion includes a second circuit board on which a circuit pattern is printed and a connector having a bar-shaped body and provided between the side end portions of the first circuit board and the second circuit board, and wherein one side surface of the body of the connector is connected to an outer surface of the first circuit board and the other side surface of the body of the connector is connected to an outer surface of the second circuit board, so that the circuit pattern of the first circuit board is continuously connected to the circuit pattern of the second circuit board, and so that the core portion is surrounded by the connector and the first and second circuit boards in a case where the first coil portion penetrates the through-hole, and wherein the one side surface has a plurality of first pins for connection with the circuit pattern of the first circuit board and the other side surface has a plurality of second pins for connection with the circuit pattern of the second circuit board. 2.The transformer according to claim 1, the connector is coupled to the first circuit board or the second circuit board by soldering. wherein 3.The transformer according to claim 1, the first coil portion is bent so that the other surface of the first circuit board on which the cutting line is formed forms an outer surface of the first coil portion and the one surface of the first circuit board on which the circuit pattern is printed is located on an inner surface of the first coil portion. wherein 4.The transformer according to claim 1, the first coil portion is bent so that the other surface of the first circuit board on which the cutting line is formed forms an inner surface of the first coil portion and the one surface of the first circuit board on which the circuit pattern is printed is located on an outer surface of the first coil portion. wherein 5.The transformer according to claim 1, further comprising a second coil portion formed with the first circuit board on one surface of which a circuit pattern is printed, the second coil portion having a shape of surrounding another portion of the core portion while penetrating the through-hole of the core portion and being formed to be bent so that side end portions of the first circuit board are connected to each other, the number of the circuit patterns printed on the first circuit boards respectively forming the first coil portion and the second coil portion are different from each other. wherein ​ 6.The transformer of claim 1, further comprising a second coil portion formed with the first circuit board on which a circuit pattern is printed on one surface, the second coil portion having a shape of surrounding another portion of the magnetic core portion while penetrating a through-hole of the magnetic core portion, and being curved so that side end portions of the first circuit board are connected to each other, wherein the first coil portion and the second coil portion are formed by stacking at least one of the first circuit boards, and the number of the first circuit boards forming the first coil portion and the second coil portion, respectively, are different from each other. 7.A method of manufacturing a transformer, comprising: printing a circuit pattern on one surface of a first circuit board and on one surface of a second circuit board; bending the first circuit board into a shape of surrounding a portion of a magnetic core portion having magnetism while penetrating a through-hole of the magnetic core portion; and forming a first coil portion by connecting side end portions of the first circuit board to each other; the method of manufacturing a transformer further comprising, before bending the first circuit board, forming a cutting line cutting a portion of the first circuit board on another surface of the first circuit board, wherein, when bending the first circuit board, the first circuit board is bent along the cutting line; and providing a connector having a bar-shaped body and disposed between the side end portions of the first circuit board and the second circuit board, wherein one side surface of the body of the connector is connected to an outer surface of the first circuit board, and another side surface of the body of the connector is connected to an outer surface of the second circuit board, so that a circuit pattern of the first circuit board is continuously connected to a circuit pattern of the second circuit board, and so that the magnetic core portion is surrounded by the connector and the first circuit board and the second circuit board in a case where the first coil portion penetrates the through-hole, and wherein the one side surface has a plurality of first pins for connection with the circuit pattern of the first circuit board, and the another side surface has a plurality of second pins for connection with the circuit pattern of the second circuit board.

8. The method of manufacturing a transformer according to claim 7, wherein, the connector is coupled with the first circuit board or the second circuit board by soldering.

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