JP5126338B2 - Transformer parts - Google Patents

Description

  The present invention relates to a transformer component, and more particularly, to a structure of a surface mount transformer component.

  As a conventional surface mount type transformer component, a transformer component using a planar coil is known. For example, the transformer component of Patent Document 1 has a configuration in which a printed coil laminate in which a core insertion hole is provided in the center and a spiral conductor pattern is formed outside thereof is sandwiched between EE cores. The printed coil laminate has a configuration in which a single base on which a spiral conductor pattern or an insulating sheet layer is formed is folded.

  Patent Document 2 includes a first planar coil that is formed on a first substrate and functions as a primary coil, and a second planar coil that is formed on a second substrate and functions as a secondary coil. A transformer is disclosed. In this transformer, the first planar coil and the second planar coil are arranged opposite to each other, and insulating beads are dispersed between them, so that the gap dimension between the planar coils can be controlled with high accuracy. It has become. Further, Patent Document 3 discloses a transformer using a plurality of base materials on which printed coils are formed. Printed coils are formed on the upper and lower surfaces of each base material, and a high-breakdown-coverage and a low-breakdown-coverage covering each printed coil are mounted.

JP-A-6-275439 JP 2000-260637 A JP-A-6-231978

  The transformer used in the booster circuit has a different winding ratio between the primary side coil and the secondary side coil, and the number of turns of the primary side coil is smaller than that of the secondary side coil, but the current flowing through the primary side coil is larger than that of the secondary side coil. large. In such a configuration, it is necessary to reduce the mounting area by narrowing the conductor width and the pitch for the secondary coil with a large number of turns, and the conductor width is wide and thick for the primary coil with a small number of turns. It is necessary to secure a large cross-sectional area by increasing the thickness and to reduce the DC resistance.

  However, in the conventional transformer component described in Patent Document 1, the primary and secondary spiral conductor patterns are formed on a single base, and a thin conductor pattern and a thick conductor pattern can be mixed. There is a problem that it is difficult. Moreover, although the conventional transformer components described in Patent Documents 2 and 3 have a primary coil and a secondary coil formed on different substrates, the substrate materials are the same, and the coil forming method is also the same. Since it is the same, there exists a problem that it is difficult to vary the thickness of a coil conductor.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is a small, thin and high-performance formed by combining a planar coil having a small cross-sectional area and a planar coil having a large cross-sectional area. It is to provide transformer parts.

  In order to solve the above problems, a transformer component according to the present invention has a magnetic substrate, a first coil formed on the magnetic substrate, an opening in the center, and is provided on the magnetic substrate. A printed circuit board, a second coil formed on the printed circuit board, and a magnetic body provided in the opening of the printed circuit board and constituting a magnetic path common to the first and second coils. It is characterized by that.

  According to the present invention, a fine thin-film coil pattern with a large number of turns can be formed on a magnetic substrate, and a wide thick film coil pattern with a small number of turns can be formed on a printed circuit board. Therefore, a small, thin and high-performance transformer component can be realized.

  In the present invention, the number of turns of the first coil is preferably larger than that of the second coil. The conductor constituting the second coil is preferably thicker than the conductor constituting the first coil, and the cross-sectional area of the conductor constituting the second coil is It is particularly preferable that the cross-sectional area of the conductor constituting one coil is larger. According to the present invention, since a thin film coil having a fine pattern formed on a magnetic substrate and a thick film coil having a thick pattern formed on a printed circuit board are magnetically coupled to each other, the structure is small, thin and high performance. Can be realized.

  In the present invention, it is preferable that the first spiral conductor includes a series connection of a plurality of spiral conductors stacked on the magnetic substrate. By increasing the number of turns by multilayering the first spiral conductor on the magnetic substrate, the inductance of the first spiral conductor can be increased.

  In the present invention, it is preferable that the first coil includes a series connection of a plurality of spiral conductors laminated on the magnetic substrate. According to this configuration, the winding ratio between the first coil and the second coil can be further increased.

  In the present invention, it is preferable that the formation region of the first coil and the formation region of the second coil substantially overlap in plan view. According to this configuration, the magnetic coupling between the first coil and the second coil can be sufficiently increased, and a transformer component with high conversion efficiency can be provided.

  According to the present invention, it is possible to provide a small, thin and high-performance transformer component configured by combining a planar coil having a small cross-sectional area and a planar coil having a large cross-sectional area.

1 is a schematic exploded perspective view showing a configuration of a transformer component according to a preferred embodiment of the present invention. FIG. 2 is a schematic side sectional view of the transformer component shown in FIG. 1. It is a flowchart which shows the manufacturing process of a transformer component, and shows the whole process roughly schematically. It is a flowchart which shows the manufacturing process of a transformer component, and shows the formation process of a thin film coil layer in detail in particular. It is a flowchart which shows the manufacturing process of a transformer component, and shows the formation process of the 3rd and 4th spiral conductor in detail in particular. It is a circuit diagram for demonstrating the relationship between the primary side coil of a transformer component, and a secondary side coil.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic exploded perspective view showing a configuration of a transformer component according to a preferred embodiment of the present invention. 2 is a schematic side sectional view of the transformer component shown in FIG.

  As shown in FIGS. 1 and 2, the transformer component 10 according to the present embodiment includes a ferrite substrate 11, a thin film coil layer 12 including first and second spiral conductors 14 and 15 formed on the ferrite substrate 11, and The printed circuit board 16 provided on the ferrite substrate 11, the third and fourth spiral conductors 17 and 18 formed on both surfaces of the printed circuit board 16, and the upper core 19 covering the upper side of the printed circuit board 16, respectively. Four terminal electrodes 20a to 20d are provided.

  The ferrite substrate 11 is a rectangular flat plate and constitutes a part of a closed magnetic circuit. Although not particularly limited, the planar dimension of the ferrite substrate 11 can be set to about 3.2 × 2.5 mm, for example. As a material of the ferrite substrate 11, it is preferable to use sintered ferrite, and it is particularly preferable to use a material having high magnetic permeability such as Ni—Cu—Zn based ferrite and Mn—Zn based ferrite. By using such a magnetic material, the magnetic characteristics of the transformer can be improved.

  The thin film coil layer 12 is formed on one main surface (upper surface) of the ferrite substrate 11. The thin film coil layer 12 is formed by laminating a first insulating layer 13a, a first spiral conductor 14, a second insulating layer 13b, a second spiral conductor 15, and a third insulating layer 13b in this order. The first spiral conductor 14 is formed on the surface of the first insulating layer 13 a formed on the ferrite substrate 11. This is because the unevenness on the surface of the ferrite substrate 11 is relaxed to ensure a flat surface and a fine pattern can be formed. However, if the ferrite substrate 11 has sufficient flatness, the first insulating layer 13a may be omitted. In that case, the first spiral conductor 14 may be formed directly on the ferrite substrate 11. The first to third insulating layers 13a to 13c can be formed by spin-coating an insulating nonmagnetic resin (for example, photosensitive polyimide resin) having photosensitivity, and exposing, developing, and thermosetting it. .

  The first and second spiral conductors 14 and 15 are circular spirals and generally overlap in a plan view, but do not completely match. That is, the first spiral conductor 14 viewed from above constitutes a counterclockwise spiral from the outer peripheral end 14a to the inner peripheral end 14b, and the second spiral conductor 15 also viewed from the upper side A counterclockwise spiral is formed from the peripheral end 15b toward the outer peripheral end 15a. As a result, the directions of the magnetic fluxes generated by the current flowing through the spiral conductors 14 and 15 coincide with each other, and the magnetic fluxes generated by the spiral conductors 14 and 15 overlap and strengthen each other, so that a large inductance can be obtained.

  The outer peripheral ends 14a and 15a of the first and second spiral conductors 14 and 15 are drawn to the side surface of the ferrite substrate 11 or the first insulating layer 13a and connected to the pair of terminal electrodes 20a and 20b, respectively. The inner peripheral end 14b of the first spiral conductor 14 and the inner peripheral end 15b of the second spiral conductor 15 are connected to each other through a contact hole conductor 13d that penetrates the second insulating layer 13b. Thus, the first and second spiral conductors 17 and 18 constitute a single coil (first coil L1) connected in series with each other.

  The first and second spiral conductors 14 and 15 are formed by a fine wiring process. Specifically, a Cu film or a multilayer film (Cr / Cu film) in which a Cu film and a Cr film are sequentially laminated is formed as a base conductive film by sputtering or vapor deposition, and then a photoresist film is formed by spin coating. Next, a negative pattern of the spiral conductor is formed by exposing and developing the photoresist film, and the base conductive film can be selectively grown by plating using this mask pattern.

  The printed circuit board 16 is a support board for providing the formation surface of the third and fourth spiral conductors 17 and 18, and has a circular opening 16a at the center. The thickness of the printed circuit board 16 can be set to about 0.06 mm, for example. The material of the printed circuit board 16 is preferably a general printed circuit board material in which a glass cloth is impregnated with an epoxy resin. For example, a BT base material, an FR4 base material, an FR5 base material, or the like can be used. Moreover, a ceramic substrate can also be used as a printed circuit board material. When these printed circuit board materials are used, the spiral conductor can be formed by plating instead of sputtering in a so-called thin film construction method, so that the thickness of the conductor can be sufficiently increased. In order to avoid an increase in stray capacitance, the printed circuit board 16 preferably has a dielectric constant of 7 or less (μ ≦ 7).

  The third and fourth spiral conductors 17 and 18 are also circular spirals, and are arranged so as to surround the opening 16 a of the printed circuit board 16. The third and fourth spiral conductors 17 and 18 substantially overlap each other in plan view, but do not completely coincide with each other. That is, the third spiral conductor 17 viewed from above forms a clockwise spiral from the outer peripheral end 17a to the inner peripheral end 17b, and the fourth spiral conductor 18 also viewed from the upper side A clockwise spiral is formed from the end 18b toward the outer peripheral end 18a. As a result, the directions of the magnetic flux generated by the current flowing through the spiral conductors 17 and 18 coincide with each other, and the magnetic fluxes generated by the spiral conductors 17 and 18 overlap and strengthen each other, so that a large inductance can be obtained.

  The outer peripheral ends 17a and 18a of the third and fourth spiral conductors 17 and 18 are drawn out to the side surface of the printed circuit board 16 and connected to the pair of terminal electrodes 20c and 20d, respectively. Further, the inner peripheral end 17 b of the third spiral conductor 17 and the inner peripheral end 18 b of the fourth spiral conductor 18 are connected to each other via a through-hole conductor 16 b that penetrates the printed circuit board 16. Thus, the first and second spiral conductors 17 and 18 constitute a single coil (second coil L2) connected in series with each other.

  In this embodiment, the formation region of the first coil L1 composed of the first and second spiral conductors 14 and 15 and the formation region of the second coil composed of the third and fourth spiral conductors 17 and 18 are flat. Substantially overlaps visually. The coil formation region here refers to a region occupied by a planar coil constituted by a spiral conductor. With such a configuration in which the coil formation regions of the first coil and the second coil overlap, the magnetic flux generated by the first coil L1 and the magnetic flux generated by the second coil L2 are superimposed and strengthened, so that a large mutual inductance is obtained. Can be obtained. Therefore, the magnetic coupling between the first coil and the second coil can be strengthened, and a transformer component with high conversion efficiency can be provided.

  Furthermore, the opposing distance between the first coil L1 composed of the first and second spiral conductors 14 and 15 and the second coil L2 composed of the third and fourth spiral conductors 17 and 18 is very short. . Only the insulating layer 13 b is interposed between the second spiral conductor 15 and the fourth spiral conductor 18. Therefore, the magnetic coupling between the first coil L1 and the second coil L2 can be further strengthened, and a transformer with high conversion efficiency can be realized.

  The third and fourth spiral conductors 17 and 18 are formed by forming a base conductive film (for example, Cu film) by electroless plating, pasting a photoresist sheet, exposing and developing the photoresist sheet, It can be formed by forming a negative pattern and selectively growing the underlying conductive film using this mask pattern. Since the thicknesses of the third and fourth spiral conductors 17 and 18 formed in this manner are sufficiently thicker than those of the first and second spiral conductors 14 and 15, the direct current resistance can be sufficiently reduced.

  The upper core 19 constitutes a part of a closed magnetic circuit together with the ferrite substrate 11. The material of the upper core 19 may be sintered ferrite or a metal magnetic powder-containing resin. The upper core 19 is an E-type core, and includes a flat plate portion 19 a, a central core portion 19 b, and two outer core portions 19 c and 19 d. The central core portion 19 b is inserted into the opening 16 a of the printed circuit board 16. Although the opening 16a is also formed in the insulating layers 13a to 13c, the lower end of the central core portion 19b does not reach the ferrite substrate 11, and an air gap G is formed between them. On the other hand, the tips of the two outer core portions 19c and 19d reach the ferrite substrate 11, and a continuous magnetic path without an air gap is formed. The ferrite substrate 11 and the upper core 19 are provided by interposing the first to third insulating layers 13a to 13c between the lower end of the central core portion 19b and the two outer core portions 19c and 19d and the ferrite substrate 11. An insulating layer gap may be formed between the two.

  The material of the upper core 19 may be a metal magnetic powder-containing resin. When the entire magnetic circuit is composed of sintered ferrite, a gap must be provided so that magnetic saturation does not occur even if a current is applied to a certain extent. However, if a resin containing metal magnetic powder is used, the metal magnetic powder and resin Since there are many minute gaps between the two, which increases the saturation magnetic flux density, the gap between the ferrite substrate 11 and the upper core 19 can be omitted.

  The metal magnetic powder-containing resin is a magnetic material in which metal magnetic powder is mixed into the resin. As the metal magnetic powder, it is preferable to use a permalloy material. Specifically, a Pb—Ni—Co alloy having an average particle diameter of 20 to 50 μm as the first metal magnetic powder and a carbonyl iron having an average particle diameter of 3 to 10 μm as the second metal magnetic powder are predetermined. It is preferable to use a metal magnetic powder containing a weight ratio of, for example, 70:30 to 80:20, preferably 75:25. The content of the metal magnetic powder is preferably 90 to 96% by weight. If the amount of metal magnetic powder is reduced relative to the resin, the saturation magnetic flux density decreases. Conversely, if the amount of metal magnetic powder is increased, the saturation magnetic flux density increases. Can be adjusted.

  Further, as the metal magnetic powder, the first metal magnetic powder having an average particle diameter of 5 μm and the second metal magnetic powder having an average particle diameter of 50 μm are mixed at a predetermined ratio, for example, 75:25. It is particularly preferable that As described above, when two types of metal magnetic powders having different particle sizes are used, a high-density magnetic core can be formed under low pressure or non-pressure forming, and high magnetic permeability and low loss can be obtained. A magnetic core can be realized.

  The resin contained in the metal magnetic powder-containing resin functions as an insulating binder. As the resin material, liquid epoxy resin or powder epoxy resin is preferably used. The resin content is preferably 4 to 10% by weight.

  A pair of terminal electrodes 20a and 20b is provided on one side surface of the two opposing side surfaces of the laminate composed of the ferrite substrate 11, the printed circuit board 16, and the upper core 19, and a pair of terminal electrodes 20a and 20b is provided on the other side surface. Terminal electrodes 20c and 20d are respectively provided. As described above, both ends of the first coil L1 including the first and second spiral conductors 14 and 15 are connected to the pair of terminal electrodes 20a and 20b, respectively, and the third and fourth spiral conductors 17, Both ends of the second coil L2 composed of 18 are connected to a pair of terminal electrodes 20c and 20d, respectively.

  The first and second spiral conductors 14 and 15 are fine patterns with a narrow pitch, and the conductor width is preferably 2 to 10 μm. According to this configuration, the first coil L1 composed of the first and second spiral conductors 14 and 15 can be preferably used as the secondary coil of the step-up transformer. Although the details will be described later, since the thin film coil layer 12 including these spiral conductors 14 and 15 is formed by a so-called thin film method, a spiral conductor having a large number of turns can be formed at a very narrow pitch.

  On the other hand, the third and fourth spiral conductors 17 and 18 are thick film patterns wider than the first and second spiral conductors 14 and 15, for example, the conductor width is 20 to 100 μm and the conductor thickness is 25 to 150 μm. It is preferable that According to this configuration, the second coil L2 composed of the third and fourth spiral conductors 17 and 18 can be preferably used as the primary coil of the step-up transformer. Although not particularly limited, the turn ratio of the primary side coil and the secondary side coil is preferably 1: 2 to 1:20. Since the third and fourth spiral conductors 17 and 18 are formed on the surface of the printed circuit board 16, they can be formed by a so-called semi-additive method.

  3 to 5 are flowcharts showing manufacturing steps of the transformer component 10.

  As shown in FIG. 3, in manufacturing the transformer component 10, a so-called mass production process is performed in which a large number of transformer components are formed on a single large substrate. The outline of the manufacturing process of the transformer component 10 is as follows. First, the ferrite substrate 11 on which the thin film coil layer 12 including the first and second spiral conductors 14 and 15 is formed is manufactured (steps S31 to S36), and the third and fourth spiral conductors 17 and 18 are formed on both surfaces. Is formed (steps S37 to S39), and after superposing them (step S40), the upper core 19 is formed on the upper surface of the printed board 11 (step S41). Thereafter, after cutting into individual components (step S42), the transformer electrodes 10 are completed by forming the terminal electrodes 20a to 20d (step S43).

  Next, the formation process of the thin film coil layer 12 on the ferrite substrate 11 will be described in detail. In forming the thin film coil layer 12, first, the ferrite substrate 11 is prepared, and the first spiral conductor 14 is formed on the ferrite substrate 11. In detail, as shown in FIG. 4, the insulating layer 13a is first formed on the ferrite substrate 11 (step S44). The insulating layer 13a can be formed by spin-coating an insulating nonmagnetic resin (for example, photosensitive polyimide resin) having photosensitivity, and exposing, developing, and thermosetting it. Next, after forming a base conductive film by sputtering or vapor deposition (step S45), a photoresist film is formed by spin coating (step S46). Next, a negative pattern of a spiral conductor is formed by exposing and developing the photoresist film (step S47), electroplating is performed using this mask pattern (step S48), and a base conductive film is selectively grown. Thereafter, the resist and unnecessary underlying conductive film are removed by etching (step S49), whereby the first spiral conductor 14 is completed.

  Next, the insulating layer 13b is formed on the ferrite substrate 11 on which the first spiral conductor 14 is formed. The formation method of the insulating layer 13b is the same as that of the insulating layer 13a. At the same time, a contact hole 13d penetrating the insulating layer 13b is also formed.

  Next, the second spiral conductor 15 is formed on the ferrite substrate 11 on which the first spiral conductor 14 and the insulating layer 13b are formed, and the insulating layer 13c is further formed thereon. The method of forming the second spiral conductor 15 is the same as that of the first spiral conductor 14, and the method of forming the insulating layer 13c is the same as that of the insulating layers 13a and 13b. Thus, the thin film coil layer 12 is completed.

  Next, the process of forming the third and fourth spiral conductors 17 and 18 on the printed circuit board 16 will be described in detail. In forming the spiral conductors 17 and 18, first, the printed circuit board 16 in which the openings 16 a and the through holes 16 b are formed is prepared, and the third spiral conductor 17 is formed on the upper surface and the back surface of the printed circuit board 16. Specifically, as shown in FIG. 5, after forming a base conductive film (for example, Cu film) on the surface of the printed circuit board 16 by electroless plating (step S50), a photoresist sheet is pasted (step S51). Next, a negative pattern of the spiral conductor is formed by exposing and developing the photoresist sheet (step S52), and electroplating is performed using this mask pattern (step S53), and the underlying conductive film is selectively grown. Thereafter, the resist and the unnecessary underlying conductive film are removed by etching (step S54), whereby the spiral conductors 17 and 18 are completed.

  Next, the printed circuit board 16 is overlaid and fixed on the ferrite substrate 11 (step S40). At that time, in order to electrically insulate and mechanically protect the third and fourth spiral conductors 17 and 18, it is preferable to form a protective film on both surfaces of the printed circuit board 16, and an adhesive is used as the protective film. Also good.

  Next, the upper core 19 is formed on the upper surface of the printed circuit board 16 (step S41). When an E-type ferrite substrate is used as the upper core 19, a ferrite substrate that has been processed into a predetermined shape may be superimposed on the printed circuit board 16 and fixed. Moreover, when using metal magnetic powder containing resin, after carrying out screen printing of metal magnetic powder containing resin paste, it defoams and it heats at 160 degreeC for 1 hour, and what is necessary is just to carry out full hardening of the resin paste.

  Thereafter, the laminate is diced into individual pieces (step S42), and then the terminal electrodes 20a to 20d are formed on the side surfaces of the individual chips (step S43), thereby completing the transformer component 10 according to the present embodiment. .

  As described above, the transformer component 10 according to the present embodiment includes the first coil L1 formed by connecting the first and second spiral conductors 14 and 15 in series on the ferrite substrate 11 and the printed circuit board 16. A transformer is constituted by a combination with the formed second coil L2 formed of a series connection of the third and fourth spiral conductors 17 and 18, the first coil L1 has a fine pattern, and the second coil L2 Since the number of turns is less than that of one coil and the pattern is thick, a small, thin and high performance transformer component can be realized.

  6A and 6B are circuit diagrams for explaining the relationship between the primary side coil and the secondary side coil of the transformer component.

  The transformer component shown in FIG. 6A is obtained by winding the first coil L1 and the second coil L2 in the opposite directions with respect to the core, and shows the configuration of the transformer component in FIG. . On the other hand, the transformer component shown in FIG. 6B is obtained by winding the first coil L1 and the second coil L2 around the core in the same direction. In the transformer component of FIG. The case where the winding directions of the first coil L1 and the second coil L2 are opposite to each other is shown. Such a configuration can be realized by connecting the outer peripheral end 14a of the first spiral conductor 14 to the terminal electrode 20b and connecting the outer peripheral end 15a of the second spiral conductor 15 to the terminal electrode 20a in FIG. Thus, the transformer component according to the present invention can arbitrarily set the winding direction of the secondary coil relative to the primary coil.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in.

  For example, in the above embodiment, the thin-film coil layer 12 has two spiral conductors 14 and 15, but the number of spiral conductor layers is not limited to two, but three or more layers. Also good. When the number of layers is increased, the number of turns of the second coil can be increased, and the winding ratio between the primary side coil and the secondary side coil can be further increased.

  In the above embodiment, the spiral conductors 17 and 18 are respectively formed on both surfaces of the printed circuit board 16, but the present invention is not limited to such a configuration, and the spiral conductor is formed only on one surface of the printed circuit board 16. It doesn't matter. It is also possible to increase the number of turns of a coil by stacking two or more printed circuit boards 16, or to increase the cross-sectional area of a conductor by connecting two coils in parallel.

  Moreover, in the said embodiment, although the ferrite substrate 11 was mentioned as a magnetic substrate which provides the formation surface of the thin film coil layer 12, the material of a magnetic substrate is not limited to a ferrite, Various magnetic materials can be used. is there.

DESCRIPTION OF SYMBOLS 10 Transformer component 11 Ferrite substrate 12 Thin film coil layer 13a, 13b, 13c Insulating layer 13d Contact hole conductor 14 1st spiral conductor 14a 1st spiral conductor outer peripheral end 14b 1st spiral conductor inner peripheral end 15 2nd Spiral conductor 15a Outer peripheral end 15b of second spiral conductor Inner peripheral end 16 of second spiral conductor Printed circuit board 16a Printed circuit board opening 16b Through-hole conductor 17 Spiral conductor 17a Outer peripheral end 17b of spiral conductor Inner peripheral end 18 of spiral conductor Spiral conductor 18a Spiral conductor outer peripheral end 18b Spiral conductor inner peripheral end 19 Upper core 19a Flat plate portion 19b Central core portions 19c, 19d Outer core portions 20a to 20d Terminal electrodes

Claims (6)

A magnetic substrate;
A first coil formed on the magnetic substrate;
A printed circuit board having an opening in the center and provided on the magnetic substrate;
A second coil formed on the printed circuit board;
A transformer component comprising: a magnetic body provided in the opening of the printed circuit board and constituting a magnetic path common to the first and second coils.   The transformer component according to claim 1, wherein the number of turns of the first coil is larger than that of the second coil.   The transformer component according to claim 2, wherein a thickness of a conductor constituting the second coil is thicker than that of the first coil.   The transformer component according to claim 2 or 3, wherein a cross-sectional area of a conductor constituting the second coil is larger than that of the first coil.   5. The transformer component according to claim 1, wherein the first coil includes a series connection of a plurality of spiral conductors stacked on the magnetic substrate. 6.   6. The transformer component according to claim 1, wherein the formation region of the first coil and the formation region of the second coil substantially overlap each other in a plan view.

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