Coil component and electronic apparatus including same

Abstract

The present disclosure provides: a coil component in which cracks are unlikely to occur in a metal conductor during the manufacturing process, and the effect of springback on the quality of the metal conductor is small; and an electronic apparatus including the coil component. The coil component (1) disclosed herein comprises: a metal conductor (2) that constitutes a coil having at least two turns; and a resin member that covers the metal conductor (2). A part of one end side of the metal conductor (2) serves an input terminal, a part of the other end side of the metal conductor (2) serves as an output terminal, and a part of an intermediate part of the metal conductor (2) serves as an intermediate terminal. A first coil (L1) formed between the input terminal and the intermediate terminal and a second coil (L2) formed between the output terminal and the intermediate terminal are magnetically coupled to each other to form a transformer. At least the input terminal, the output terminal, and the intermediate terminal are exposed on the same surface of the resin member.

Description

Coil component, electronic device including the same

[0001] The present disclosure relates to a coil component and an electronic device including the same.

[0002] In an electronic device, noise countermeasures may be taken using a filter circuit. A coil component is used in the filter circuit. For example, a coil component including a coil portion formed of an integral metal conductor wound in the same direction and an intermediate terminal provided in the middle of the coil portion is known (for example, Japanese Unexamined Patent Application Publication No. 2021-118331: Patent Document 1).

[0003] Japanese Unexamined Patent Application Publication No. 2021-118331

[0004] However, in the structure of the coil component described in Japanese Unexamined Patent Application Publication No. 2021-118331 (Patent Document 1), it is necessary to manufacture by bending an integral metal conductor multiple times, and there is a risk of cracking at the bending points of about 180 degrees. Further, the manufacturing process of the coil component is complicated, and springback occurs in the metal conductor due to the structure where multiple bending points of about 180 degrees overlap, making it difficult to stably manufacture the distance between the metal conductors, and there is a risk of deterioration in the quality of the coil component.

[0005] Therefore, an object of the present disclosure is to provide a coil component in which cracks are less likely to occur in the metal conductor during the manufacturing process and the influence on the quality due to springback of the metal conductor is small, and an electronic device including the same.

[0006] A coil component according to one aspect of the present disclosure includes a metal conductor constituting at least two or more turns of a coil and a resin member covering the metal conductor. A part of one end side of the metal conductor is an input terminal, a part of the other end side of the metal conductor is an output terminal, and a part of the middle portion of the metal conductor is an intermediate terminal. A first coil formed between the input terminal and the intermediate terminal and a second coil formed between the output terminal and the intermediate terminal are magnetically coupled to each other to form a transformer. At least the input terminal, the output terminal, and the intermediate terminal are exposed on the same surface of the resin member.

[0007] An electronic device according to one aspect of the present disclosure includes the above-described coil component.

[0008] According to one embodiment of the present disclosure, a metal conductor constituting at least two or more turns of a coil is covered with a resin member, and at least the input terminal, output terminal, and intermediate terminal are exposed on the same surface of the resin member. This makes it less likely for cracks to occur in the metal conductor during the manufacturing process of the coil component, and reduces the impact on quality due to springback of the metal conductor.

[0009] This is a perspective view of a coil component according to Embodiment 1. This is a perspective view of a coil component according to Embodiment 1, viewed from the bottom. This is a side view of a coil component according to Embodiment 1. This is a circuit diagram of a filter circuit including a coil component according to Embodiment 1. This is a perspective view of a coil component according to Modification 1. This is a side view of a coil component according to Modification 1. This is a perspective view and side view of a coil component with a different housing shape from Modification 1. This is a perspective view of a coil component according to Modification 2. This is a plan view and side view of a coil component according to Modification 2. This is a perspective view of a coil component according to Embodiment 2. This is a perspective view of a coil component according to Embodiment 2, viewed from the bottom. This is a plan view and side view of a coil component according to Embodiment 2. This is a perspective view of a coil component according to Embodiment 3. This is a plan view of a metal conductor according to Embodiment 3. This is a perspective view of a coil component according to a modification of Embodiment 3. This is a plan view of a metal conductor according to a modification of Embodiment 3. This is a perspective view of a coil component according to Embodiment 4. This is a top view and side view of a coil component according to Embodiment 4.

[0010] The coil component and the electronic device containing it relating to this disclosure will be described below with reference to the drawings.

[0011] <Embodiment 1> First, the coil component according to Embodiment 1 will be described with reference to the drawings. Figure 1 is a perspective view of the coil component 1 according to Embodiment 1. Figure 2 is a perspective view of the coil component 1 according to Embodiment 1, viewed from the bottom. Figure 3 is a side view of the coil component 1 according to Embodiment 1. Figure 3(a) is a side view of the coil component 1 viewed from the Y-Z plane, and Figure 3(b) is a side view of the coil component 1 viewed from the X-Z plane. Figure 4 is a circuit diagram of a filter circuit 100 including the coil component according to Embodiment 1. Note that the X-axis, Y-axis, and Z-axis defined in Figures 1 to 3 represent the direction of the short side of the coil component 1 in the X-axis direction, the Y-axis direction in the direction of the long side of the coil component 1 in the Y-axis direction, and the Z-axis direction in the height direction of the coil component 1 in the Z-axis direction.

[0012] The coil component 1 is, for example, a transformer coil implemented in a filter circuit 100 used for noise suppression in power lines, and is used in electronic equipment such as power supplies. The coil component 1 is not limited to power supplies and may be used in electronic equipment other than power supplies. As will be described later, the coil component 1 can cancel the parasitic inductance of a capacitor connected to the filter circuit 100 by magnetically coupling two coils.

[0013] The coil component 1 includes a housing 4 and a metal conductor 2 that constitutes a coil of approximately 2.5 turns. The metal conductor 2 is formed from a metal plate or metal wire of, for example, copper or an alloy of copper mixed with other metals. Furthermore, the metal conductor 2 may be subjected to surface treatments such as Ni, Sn plating or gold plating. In this embodiment, the cross-sectional shape of the metal conductor 2 is described as rectangular, as shown in Figure 1. The coil composed of the metal conductor 2 has one winding axis I, and the opening surface (X-Z plane) of the coil is arranged to be perpendicular to the top surface 40A and the bottom surface 40B of the housing 4. In other words, the coil composed of the metal conductor 2 is wound in the Y direction, not the Z direction. The shape of the coil composed of the metal conductor 2 as seen from the winding axis I is rectangular. Therefore, a wide opening for the coil can be secured in the rectangular parallelepiped housing 4.

[0014] The housing 4 fixes the spacing between the wound metal conductors 2 and is a resin member that covers the metal conductors 2. The resin member may be a molded resin material or a dip-molded resin material. The resin member is, for example, a mixed material obtained by mixing a magnetic material such as ferrite powder or metal powder with a resin such as epoxy resin, silicone resin, or liquid crystal polymer with silica filler. The housing 4 has sides 41 and 42 facing each other, and sides 43 and 44 facing each other. Figure 1 shows a rectangular parallelepiped shape, but it is sufficient that the bottom surface 40B, which is the mounting surface to the substrate, is approximately parallel, and it may be a truncated square pyramid, for example, where the area of ​​the bottom surface 40B is larger than the area of ​​the top surface 40A.

[0015] The coil, composed of metal conductors 2, is wound in the Y direction, with each conductor bent approximately 90 degrees from one end conductor 2a to the other end conductor 2k. Therefore, there are no points in the coil component 1 where the metal conductors 2 are bent approximately 180 degrees, making the metal conductors 2 less susceptible to cracking. Furthermore, since the coil component 1 does not have a structure where multiple points of approximately 180-degree bending overlap, the impact on quality due to springback of the metal conductors 2 is minimal.

[0016] Furthermore, although the coil, which is composed of metal conductors 2, is located inside the housing 4, the portions of conductors 2b, 2f, and 2j are exposed from the bottom surface 40B of the housing 4. The exposed portions of conductors 2b, 2f, and 2j constitute the input terminal, intermediate terminal, and output terminal, respectively, of the coil component 1. In other words, the metal conductor 2 has a portion of one end (conductor 2b) as the input terminal, a portion of the other end (conductor 2j) as the output terminal, and a portion of the middle section (conductor 2f) as the intermediate terminal. As shown in Figure 2, the input terminal, intermediate terminal, and output terminal of the coil component 1 are exposed from the same bottom surface 40B (same plane) of the housing 4. In addition, in the coil component 1, the intermediate terminal is composed of conductor 2f, which is a part of the metal conductor 2, and is integrally formed as the metal conductor 2. This improves strength and reliability compared to configurations where the intermediate terminal is later provided separately by soldering, welding, crimping, etc.

[0017] The coil component 1 has its input terminals, intermediate terminals, and output terminals exposed from its bottom surface 40B, allowing it to be positioned with its bottom surface 40B facing the substrate and soldered to each terminal and each electrode on the substrate. It is preferable that the portion of the metal conductor 2 greater than or equal to the plate thickness of the input terminals, intermediate terminals, and output terminals is exposed from the bottom surface 40B. In other words, as shown in Figure 3(b), the input terminals, intermediate terminals, and output terminals are exposed from the bottom surface 40B so that there is a gap between the input terminals, intermediate terminals, and output terminals and the bottom surface 40B. By providing a gap between the input terminals, intermediate terminals, and output terminals and the bottom surface 40B in this way, the stress applied to the input terminals, intermediate terminals, and output terminals when the coil component 1 is mounted on the substrate can be reduced, and the stress resistance of the coil component 1 during mounting can be improved.

[0018] The first coil L1 is formed from the input terminal conductor 2b to conductors 2c, 2d, 2e, and the intermediate terminal conductor 2f. The second coil L2 is formed from the output terminal conductor 2j to conductors 2i, 2h, 2g, and the intermediate terminal conductor 2f. The first coil L1 and the second coil L2 are magnetically coupled to each other to form a transformer.

[0019] When coil component 1 is mounted on a circuit board, conductor 2b (input terminal) is electrically connected to an input electrode (not shown) on the circuit board, and conductor 2j (output terminal) is electrically connected to an output electrode (not shown) on the circuit board. In addition, conductor 2f is electrically connected to an intermediate electrode (not shown) on the circuit board and functions as an intermediate terminal of coil component 1 that connects the first coil L1 and the second coil L2 in series.

[0020] When the conductor 2b (input terminal) of the first coil L1 is connected to a power source, current flows from conductor 2b in a counterclockwise direction, viewed from the side 41, through conductors 2c, 2d, 2e, and 2f. Similarly, when viewed from the side 41, current flows from the intermediate terminal conductor 2f of the second coil L2 in a counterclockwise direction, through conductors 2g, 2h, 2i, and 2j (output terminal). As a result, a magnetic field is generated in the direction from side 42 towards side 41 (Y direction) by both the first coil L1 and the second coil L2.

[0021] The filter circuit 100 on which the coil component 1 is mounted is, for example, an EMI rejection filter, as shown in Figure 4, and is a third-order T-type LC filter circuit. This filter circuit 100 connects conductor 2b (input terminal) to a power supply (not shown) and conductor 2j (output terminal) to a circuit (not shown) such as a DC / DC converter or power supply module. The filter circuit 100 removes unwanted components from the current flowing from the power supply to the circuit, allowing only the necessary components to pass through.

[0022] Specifically, a DC current is passed through the filter circuit 100, and the high-frequency noise contained in the DC current is grounded through the capacitor 50. The capacitor 50, being a capacitance element, has parasitic inductance (equivalent series inductance (ESL)) in the form of an inductor 50B in addition to the capacitor 50A, which hinders the passage of high-frequency noise and degrades the noise rejection performance. In the filter circuit 100, as described later, the parasitic inductance (inductor 50B) of the capacitor 50 is canceled out by the negative inductance generated by the magnetic coupling of the two coils, thereby maintaining high noise rejection performance. In this disclosure, the negative inductance generated in series with respect to this capacitor 50 is called the mutual inductance (-M) of the coil component 1.

[0023] Although the filter circuit 100 described in this disclosure is a third-order T-type LC filter circuit, the same coil components of this disclosure can be applied to fifth-order T-type LC filter circuits and higher-order T-type LC filter circuits. As shown in Figure 4, the filter circuit 100 includes a coil component 1 and a capacitor 50.

[0024] As shown in Figure 4, capacitor 50 has one end connected to conductor 2f (intermediate terminal) and the other end connected to GND wiring. Note that capacitor 50 is BaTiO ３The capacitor may be a multilayer ceramic capacitor primarily composed of barium titanate, a multilayer ceramic capacitor primarily composed of other materials, or a capacitor of a different type, such as an aluminum electrolytic capacitor. Capacitor 50 has an inductor 50B as a parasitic inductance, and is equivalent to a circuit configuration in which inductor 50B is connected in series with capacitor 50A. Capacitor 50 may also be equivalent to a circuit configuration in which parasitic resistance (equivalent series resistance (ESR)) is connected in series with inductor 50B and capacitor 50A.

[0025] In addition to the capacitor 50, a first coil L1 and a second coil L2 are connected to the conductor 2f (intermediate terminal). The first coil L1 and the second coil L2 are magnetically coupled and have a mutual inductance (-M). A negative inductance component equal to the mutual inductance M is generated between the conductor 2f (intermediate terminal) and the capacitor 50. This negative inductance component can be used to cancel out the parasitic inductance (inductor 50B) of the capacitor 50, thereby making the parasitic inductance component of the capacitor 50 appear smaller. By making the parasitic inductance component of the capacitor 50 appear smaller, the filter circuit 100 can suppress the reduction in the noise suppression effect in the high-frequency band due to the parasitic inductance of the capacitor 50 and improve the noise suppression effect of the filter circuit 100.

[0026] (Modification 1) In the coil component 1 shown in Figure 1, it was explained that it includes a housing 4 and a metal conductor 2 that constitutes a coil of approximately 2.5 turns. However, the number of turns of the coil is not limited to approximately 2.5 turns, and it is sufficient if it is at least 2 turns or more. Below, a coil component including a coil of approximately 4.5 turns will be described as a modification. Figure 5 is a perspective view of the coil component 1A according to Modification 1. Figure 6 is a side view of the coil component 1A according to Modification 1. Figure 6(a) is a side view of the coil component 1A viewed from the Y-Z plane, and Figure 6(b) is a side view of the coil component 1A viewed from the X-Z plane. Note that in the coil component 1A shown in Figures 5 and 6, the same reference numerals are used for the same components as in the coil component 1 shown in Figures 1 to 3, and detailed explanations will not be repeated.

[0027] The coil component 1A includes a housing 4 and a metal conductor 2 that constitutes a coil of approximately 4.5 turns. The coil made of the metal conductor 2 has multiple winding axes I and J, and the opening surface (X-Z plane) of the coil is arranged to be perpendicular to the top surface 40A and the bottom surface 40B of the housing 4. In other words, the coil made of the metal conductor 2 includes a coil with winding axis I as the winding axis and a coil with winding axis J as the winding axis. Specifically, the coil made up of conductor 2a to conductor 2e, the coil made up of conductor 2i to conductor 2m, and the coil made up of conductor 2o to conductor 2s are coils with winding axis I as the winding axis. The coil made up of conductor 2e to conductor 2i, and the coil made up of conductor 2m to conductor 2q are coils with winding axis J as the winding axis.

[0028] The coil, composed of metal conductors 2, is wound in the Y direction, with each conductor bent approximately 90 degrees relative to the others between conductor 2a at one end and conductor 2s at the other end. Therefore, the coil component 1A does not have any points where the metal conductors 2 are bent approximately 180 degrees, making it less susceptible to cracking of the metal conductors 2. Furthermore, since the coil component 1A does not have a structure where multiple points of approximately 180-degree bending overlap, the impact on quality due to springback of the metal conductors 2 is minimal.

[0029] Furthermore, the coil, which is made up of metal conductors 2, is located inside the housing 4, but the conductors 2b, 2j, and 2r are exposed from the bottom surface 40B of the housing 4. The exposed conductors 2b, 2j, and 2r constitute the input terminal, intermediate terminal, and output terminal of the coil component 1A, respectively. As shown in Figure 6(a), the input terminal, intermediate terminal, and output terminal of the coil component 1A are exposed from the same bottom surface 40B of the housing 4. In addition, in the coil component 1A, the intermediate terminal is made of conductor 2j, which is part of the metal conductor 2, and is integrally formed as the metal conductor 2, which improves strength and reliability compared to a configuration in which the intermediate terminal is later provided separately by soldering, welding, crimping, etc.

[0030] Coil component 1A has conductors 2b, 2j, and 2r exposed from the bottom surface 40B, but conductors 2f and 2n are not exposed from the bottom surface 40B. Since coil component 1A does not expose conductors 2f and 2n from the bottom surface 40B, the winding axis of the coil including conductors 2f and 2n is designated as winding axis J. However, coil component 1A may also expose conductors 2f and 2n from the bottom surface 40B. In this case, for example, the winding axis of the coil including conductors 2f and 2n may be the same winding axis I as the winding axis of the coil including conductors 2b, 2j, and 2r.

[0031] The coil component 1A has its input terminal, intermediate terminal, and output terminal exposed from its bottom surface 40B, allowing it to be positioned with its bottom surface 40B facing the substrate, and enabling soldering between each terminal and each electrode on the substrate. It is preferable that the portion of the metal conductor 2 that is greater than or equal to the plate thickness of the input terminal, intermediate terminal, and output terminal is exposed from the bottom surface 40B.

[0032] Coil component 1A forms the first coil L1 from the input terminal conductor 2b to conductors 2c, 2d, 2e, 2f, 2g, 2h, 2i, and the intermediate terminal conductor 2j. Coil component 1A also forms the second coil L2 from the output terminal conductor 2r to conductors 2q, 2p, 2o, 2n, 2m, 2l, 2k, and the intermediate terminal conductor 2j. The first coil L1 and the second coil L2 are magnetically coupled to each other to form a transformer.

[0033] When coil component 1A is mounted on a circuit board, conductor 2b (input terminal) is electrically connected to an input electrode (not shown) on the circuit board, and conductor 2r (output terminal) is electrically connected to an output electrode (not shown) on the circuit board. In addition, conductor 2j is electrically connected to an intermediate electrode (not shown) on the circuit board and functions as an intermediate terminal of coil component 1 that connects the first coil L1 and the second coil L2 in series.

[0034] When the input terminal of the first coil L1 is connected to the power supply, current flows from conductor 2b in a counterclockwise direction as viewed from the side 41, through conductors 2c, 2d, 2e, 2f, 2g, 2h, 2i, and 2j. When viewed from the side 41, current flows from the intermediate terminal conductor 2j of the second coil L2 in a counterclockwise direction as viewed from the side 41, through conductors 2k, 2l, 2m, 2n, 2o, 2p, 2q, and 2r (output terminal). As a result, a magnetic field is generated in the direction from side 42 towards side 41 (Y direction) by both the first coil L1 and the second coil L2.

[0035] In the coil component 1A shown in Figure 5, a bottom surface 40B is provided at a position where the conductors 2f and conductors 2n are not exposed from the housing 4, and the bottom surface 40B is formed as a flat surface. However, it is not necessary for the bottom surface 40B to be flat; irregularities may be provided on the bottom surface 40B so that the conductors 2f and conductors 2n are not exposed from the housing 4. Figure 7 shows a perspective view and a side view of the coil component 1Aa, which is a different housing shape of the modified example 1. Figure 7(a) is a perspective view of the coil component 1Aa, and Figure 7(b) is a side view of the coil component 1Aa viewed from the Y-Z plane. Note that in the coil component 1Aa shown in Figure 7, the same reference numerals are used for the same components as in the coil component 1A shown in Figures 5 and 6, and detailed explanations are not repeated.

[0036] As shown in Figures 7(a) and 7(b), the bottom surface 40B of the housing 4 has irregularities that conform to the shapes of the conductors 2f and 2n. The bottom surface 40B is provided with steps to prevent the conductors 2f and 2n from being exposed from the housing 4. When soldering the coil component 1Aa to the substrate, by providing steps on the bottom surface 40B and lengthening the exposed portion of terminals such as the conductor 2b (input terminal), the solder fillet on the side of the terminal can be made higher, thereby increasing the bonding strength between the terminal and the substrate.

[0037] (Modification 2) In the coil component 1 shown in Figure 1, the coil made of metal conductor 2 is described in which the winding direction of the first coil L1 and the second coil L2 is the same direction (-Y direction). However, the winding direction of the first coil L1 and the second coil L2 may be different. Below, as a modification, a coil component in which the winding direction of the first coil L1 and the second coil L2 are different will be described. Figure 8 is a perspective view of the coil component 1B according to Modification 2. Figure 9 is a plan view and a side view of the coil component 1B according to Modification 2. Figure 9(a) is a side view of the coil component 1B viewed from the Y-Z plane, Figure 9(b) is a side view of the coil component 1B viewed from the X-Z plane, and Figure 9(c) is a plan view of the coil component 1B viewed from the X-Y plane. Note that in the coil component 1B shown in Figures 8 and 9, the same reference numerals are used for the same components as in the coil component 1 shown in Figures 1 to 3, and detailed explanations will not be repeated.

[0038] Coil component 1B includes a housing 4 and a metal conductor 2 that constitutes a coil of approximately 4 turns. Coil component 1B constitutes the first coil L1 from the input terminal conductor 2a to conductors 2b, 2c, 2d, 2e, 2f, 2g, 2h, and the intermediate terminal conductor 2i. The winding direction of the first coil L1 is in the +Y direction. Coil component 1B constitutes the second coil L2 from the output terminal conductor 2q to conductors 2p, 2o, 2n, 2m, 2l, 2k, 2j, and the intermediate terminal conductor 2i. The winding direction of the first coil L1 is in the -Y direction. In other words, coil component 1B reverses the winding direction at the intermediate terminal conductor 2i.

[0039] The coil, composed of metal conductors 2, is located inside the housing 4, but the conductors 2a, 2i, and 2q are exposed from the bottom surface 40B of the housing 4. The exposed conductors 2a, 2i, and 2q constitute the input terminal, intermediate terminal, and output terminal, respectively, of the coil component 1B. As shown in Figure 9, the input terminal, intermediate terminal, and output terminal of the coil component 1B are exposed from the same bottom surface 40B of the housing 4. Note that the coil component 1B has a structure in which the winding direction of the first coil L1 and the winding direction of the second coil L2 are reversed at the intermediate terminal conductor 2i, so the conductor 2a (input terminal) and conductor 2q (output terminal) are located on the side surface 42, and the conductor 2i (intermediate terminal) is located on the side surface 41. In other words, in coil component 1B, the conductor 2a (input terminal), conductor 2q (output terminal), and conductor 2i (intermediate terminal) are provided on opposing sides of the housing 4, thus improving the isolation between the input / output terminals and the intermediate terminal.

[0040] When the input terminal of the first coil L1 is connected to the power supply, current flows from conductor 2a counterclockwise as viewed from the side 42 side in the order of conductor 2b, conductor 2c, conductor 2d, conductor 2e, conductor 2f, conductor 2g, conductor 2h, and conductor 2i. When viewed from the side 42 side of the second coil L2, current flows from the intermediate terminal conductor 2i counterclockwise in the order of conductor 2j, conductor 2k, conductor 2l, conductor 2m, conductor 2n, conductor 2o, conductor 2p, and conductor 2q (output terminal). As a result, the first coil L1 and the second coil L2 generate a magnetic field in the direction from side 41 to side 42 (-Y direction). The first coil L1 and the second coil L2 are magnetically coupled to each other to form a transformer.

[0041] <Embodiment 2> In the coil component 1 according to Embodiment 1, the cross-sectional shape of the metal conductor 2 was described as rectangular, but the cross-sectional shape of the metal conductor 2 may be other than rectangular. In the coil component according to Embodiment 2, the case in which the cross-sectional shape of the metal conductor is circular will be described. Figure 10 is a perspective view of the coil component 1C according to Embodiment 2. Figure 11 is a perspective view of the coil component 1C according to Embodiment 2, viewed from the bottom. Figure 12 is a plan view and a side view of the coil component 1C according to Embodiment 2. Figure 12(a) is a plan view of the coil component 1C viewed from the X-Y plane, and Figure 12(b) is a side view of the coil component 1C viewed from the X-Z plane. In the coil component 1C shown in Figures 10 to 12, the same reference numerals are used for the same components as in the coil component 1 shown in Figures 1 to 3, and detailed explanations will not be repeated.

[0042] The coil component 1C includes a housing 4 and a metal conductor 20 that constitutes a coil of approximately two turns. The metal conductor 20 is a metal wire made of, for example, copper or an alloy of copper and other metals, and has a circular cross-sectional shape. Furthermore, the metal conductor 20 may be surface-treated with Ni, Sn plating or gold plating. The coil made of the metal conductor 20 has one winding axis I, and the opening surface (X-Z plane) of the coil is positioned perpendicular to the top surface 40A and bottom surface 40B of the housing 4. In other words, the coil made of the metal conductor 20 is wound in the Y direction, not the Z direction. The shape of the coil made of the metal conductor 20 as seen from the winding axis I is circular. When the shape of the coil is circular, it is not possible to secure a wider opening for the coil compared to when it is rectangular, but the shape of the coil may be circular as long as the necessary opening can be secured.

[0043] The coil formed by the metal conductor 20 is wound in the Y direction while being bent circularly from the conductor 20a at one end to the conductor 20c at the other end. Therefore, there is no location where the metal conductor 20 is bent by approximately 180 degrees in the coil component 1C, making it difficult for cracks to occur in the metal conductor 20. Furthermore, since the coil component 1C does not have a structure where multiple locations of approximately 180-degree bending overlap, the impact on the quality due to the springback of the metal conductor 20 is small. By bending the metal conductor 20 circularly, the impact on the quality due to springback is even less compared to the coil component 1 where the metal conductor 2 is wound while being bent by approximately 90 degrees.

[0044] Also, the coil formed by the metal conductor 20 is provided inside the housing 4, but the portions of the conductor 20a, conductor 20b, and conductor 20c are exposed from the bottom surface 40B of the housing 4. The exposed portions of the conductor 20a, conductor 20b, and conductor 20c respectively constitute the input terminal, intermediate terminal, and output terminal of the coil component 1C. As shown in FIG. 11, in the coil component 1C, the input terminal, intermediate terminal, and output terminal are exposed from the same bottom surface 40B of the housing 4. Also, in the coil component 1C, since the intermediate terminal is formed by the conductor 20b which is a part of the metal conductor 20 and is integrally formed as the metal conductor 2, the strength and reliability are improved compared to a configuration where the intermediate terminal is separately provided later by soldering, welding, caulking, etc.

[0045] By exposing the input terminal, intermediate terminal, and output terminal from the bottom surface 40B, the coil component 1C can be arranged such that the bottom surface 40B faces the substrate, and each terminal can be soldered to each electrode on the substrate. In the input terminal, intermediate terminal, and output terminal, it is preferable to expose a portion that is larger than the wire diameter (equivalent to the plate thickness) of the metal conductor 20 from the bottom surface 40B. That is, as shown in FIG. 12(b), the input terminal, intermediate terminal, and output terminal are exposed from the bottom surface 40B so that a gap is formed between the input terminal, intermediate terminal, and output terminal and the bottom surface 40B.

[0046] A first coil L1 is formed between a conductor 20a which is an input terminal and a conductor 20b which is an intermediate terminal. Also, a second coil L2 is formed between a conductor 2c which is an output terminal and a conductor 2b which is an intermediate terminal. The first coil L1 and the second coil L2 are magnetically coupled to each other to form a transformer.

[0047] When the conductor 20a (input terminal) of the first coil L1 is connected to a power source, current flows clockwise from the conductor 20a to the conductor 2b which is an intermediate terminal as viewed from the side of the side surface 41. Also, in the second coil L2, current flows clockwise from the conductor 2b which is an intermediate terminal to the conductor 20c (output terminal) as viewed from the side of the side surface 41. Therefore, a magnetic field is generated in the direction from the side surface 41 to the side surface 42 (-Y direction) in the first coil L1 and the second coil L2.

[0048] <Embodiment 3> In the coil component 1 according to Embodiment 1, a configuration in which a single metal conductor 2 is wound and a part of the intermediate portion of the metal conductor 2 is used as an intermediate terminal has been described. In the coil component according to Embodiment 3, a configuration in which a branching portion is provided that branches a single metal conductor into two conductors and one of the conductors is used as an intermediate terminal will be described. FIG. 13 is a perspective view of a coil component 1D according to Embodiment 3. FIG. 13(a) is a perspective view of such a coil component 1D as viewed from the side surface 43 side, and FIG. 13(b) is a perspective view of such a coil component 1D as viewed from the side surface 44 side. FIG. 14 is a plan view of a metal conductor 30 according to Embodiment 3. In the coil component 1D shown in FIG. 13, the same reference numerals are given to the same components as those of the coil component 1 shown in FIGS. 1 to 3, and detailed description thereof will not be repeated.

[0049] The coil component 1D includes a housing 4 and a metal conductor 30 that forms a coil of approximately 2.5 turns. The metal conductor 30 is formed from, for example, a metal plate or metal wire of copper or an alloy of copper mixed with other metals. Further, the metal conductor 30 may be subjected to surface treatment such as Ni, Sn plating or gold plating. Note that the cross-sectional shape of the metal conductor 30 is rectangular as shown in FIG. 13. Also, the metal conductor 30 has a branching portion 35 that branches from a single conductor into a first conductor 31 and a second conductor 32 shorter than the first conductor 31 as shown in FIG. 14.

[0050] In coil component 1D, the first conductor 31 constitutes the first coil L1, and the conductor 30a, which is the end of the first conductor 31, functions as an input terminal. In coil component 1D, the conductor 30b, which is the end of the second conductor 32, functions as an intermediate terminal, and the portion 36 of the unbranched metal conductor 30 constitutes the second coil L2. In coil component 1D, the winding axis of the first coil L1, which is made up of the first conductor 31, and the winding axis of the second coil L2, which is made up of the portion 36 of the unbranched metal conductor 30, are the same, and the opening surface (X-Z plane) of the coil is positioned perpendicular to the top surface 40A and the bottom surface 40B of the housing 4. The first coil L1 and the second coil L2 are magnetically coupled to each other to form a transformer.

[0051] In the coil component 1D, the conductor 30c, which is the end of the metal conductor 30, functions as an output terminal. As shown in Figure 13, the input terminal, intermediate terminal, and output terminal of the coil component 1D are exposed from the same bottom surface 40B of the housing 4. By exposing the input terminal, intermediate terminal, and output terminal of the coil component 1D from the bottom surface 40B, the coil component 1D can be positioned with its bottom surface 40B facing the substrate, allowing each terminal to be soldered to each electrode on the substrate.

[0052] When the conductor 30a (input terminal) of the first coil L1 is connected to a power source, current flows from conductor 30a to the intermediate terminal conductor 30b in a counterclockwise direction when viewed from the side 41. Similarly, when viewed from the side 41, current flows from the intermediate terminal conductor 30b to the intermediate terminal conductor 30c (output terminal) of the second coil L2 in a counterclockwise direction. As a result, the first coil L1 and the second coil L2 generate a magnetic field from the side 42 towards the side 41 (Y direction).

[0053] The coil component 1D allows for adjustment of the ratio of turns of the first coil L1 to the number of turns of the second coil L2 by changing the position of the branching portion 35 in the metal conductor 30. Furthermore, by using the intermediate terminal conductor 30b as the end of the second conductor 32 and drawing it out independently from the first conductor 31, the mountability of the coil component 1D and the solderability of the intermediate terminal to the circuit board are improved.

[0054] (Modified Version) In coil component 1D, a metal conductor 30 is used that branches from a branching portion 35 into a first conductor 31 and a second conductor 32 which is shorter than the first conductor 31. Therefore, the width of the first conductor 31 that constitutes the first coil L1 and the width of portion 36 of the metal conductor 30 that constitutes the second coil L2 are different. In the modified coil component, the width of the conductor that constitutes the first coil L1 and the width of the conductor that constitutes the second coil L2 are the same. Figure 15 is a perspective view of coil component 1E according to a modified version of Embodiment 3. Figure 15(a) is a perspective view of coil component 1E seen from the side 43, and Figure 15(b) is a perspective view of coil component 1E seen from the side 44. Figure 16 is a plan view of metal conductor 30A according to a modified version of Embodiment 3. In coil component 1E shown in Figure 15, the same reference numerals are used for the same components as coil component 1 shown in Figures 1 to 3 and coil component 1D shown in Figure 13, and detailed explanations are not repeated.

[0055] The coil component 1E includes a housing 4 and a metal conductor 30A that constitutes a coil of approximately 2.5 turns. The metal conductor 30A is formed from a metal plate or metal wire of, for example, copper or an alloy of copper mixed with other metals. Furthermore, the metal conductor 30A may be subjected to surface treatment such as Ni, Sn plating or gold plating. The cross-sectional shape of the metal conductor 30A is rectangular, as shown in Figure 15. The metal conductor 30A also has a branching section 35A from which a single conductor branches into a first conductor 31A and a second conductor 32A that is shorter than the first conductor 31A, as shown in Figure 16. Furthermore, the shape of the portion 36A of the unbranched metal conductor 30A is formed so that its width is the same as the width of the first conductor 31A.

[0056] In coil component 1E, by making the width of the first conductor 31A constituting the first coil L1 the same as the width of portion 36A of the metal conductor 30A constituting the second coil L2, the bending stress of the metal conductor 30A can be kept constant, making manufacturing easier. Furthermore, when the metal conductor 30A is bent to form the shape of the coil opening into a rectangle, as shown in coil component 1 in Figure 1, it is easier to form than the metal conductor 30 shown in Figure 14. In addition, the cross-sectional shape of the metal conductor 30 and metal conductor 30A may be a shape other than a rectangle, for example, a circle as shown in the metal conductor 20 in Figure 10.

[0057] <Embodiment 4> In the coil component 1 according to Embodiment 1, the opening surface of the coil, which is made of a metal conductor 2, is perpendicular to the surface of the resin member on which the input terminal (conductor 2b), output terminal (conductor 2j), and intermediate terminal (conductor 2f) are exposed. In the coil component according to Embodiment 4, the opening surface of the coil, which is made of a metal conductor, is parallel to the surface of the resin member on which the input terminal, output terminal, and intermediate terminal are exposed. Figure 17 is a perspective view of the coil component 1F according to Embodiment 4. Figure 18 is a top view and a side view of the coil component 1F according to Embodiment 4. Figure 18(a) is a top view of the coil component 1F as seen from the X-Y plane, and Figure 18(b) is a side view of the coil component 1F as seen from the Y-Z plane. Note that in the coil component 1F shown in Figures 17 and 18, the same reference numerals are used for the same components as those shown in the coil component 1 in Figures 1 to 3, and detailed explanations are not repeated.

[0058] The coil component 1F includes a housing 4 and a metal conductor 2 that constitutes a coil of approximately 3.5 turns. The metal conductor 2 is formed from a metal plate or metal wire of, for example, copper or an alloy of copper mixed with other metals. Furthermore, the metal conductor 2 may be subjected to surface treatment such as Ni, Sn plating or gold plating. In Embodiment 4, the cross-sectional shape of the metal conductor 2 is described as rectangular as shown in Figure 17, but it may be other shapes. The coil composed of the metal conductor 2 has one winding axis I, and the opening surface (X-Y plane) of the coil is arranged to be parallel to the top surface 40A and the bottom surface 40B of the housing 4. In other words, the coil composed of the metal conductor 2 is wound in the Z direction, not the Y direction. The shape of the coil composed of the metal conductor 2 as seen from the winding axis I is rectangular. Therefore, a wide opening for the coil can be secured in the rectangular parallelepiped housing 4. The shape of the coil composed of the metal conductor 2 as seen from the winding axis I is not limited to a rectangle, but may be other shapes such as a circle.

[0059] The coil component 1F is constructed from a metal conductor 2, and the coil is wound in the Z direction, with each conductor bent approximately 90 degrees from one end 2a to the other end 2g. The coil of the coil component 1F is located inside the housing 4, but the portions of conductors 2a, 2d, and 2g are exposed from the bottom surface 40B of the housing 4. The exposed portions of conductors 2a, 2d, and 2g constitute the input terminal, intermediate terminal, and output terminal of the coil component 1F, respectively. In other words, the metal conductor 2 has a portion at one end (conductor 2a) as the input terminal, a portion at the other end (conductor 2g) as the output terminal, and a portion in the middle (conductor 2d) as the intermediate terminal. As shown in Figure 18(b), the input terminal, intermediate terminal, and output terminal of the coil component 1F are exposed from the same bottom surface 40B (same plane) of the housing 4.

[0060] Coil component 1F constitutes the first coil L1 from the input terminal conductor 2a to conductors 2b, 2c, and the intermediate terminal conductor 2d. Coil component 1F also constitutes the second coil L2 from the output terminal conductor 2g to conductors 2f, 2e, and the intermediate terminal conductor 2d. The first coil L1 and the second coil L2 are magnetically coupled to each other to form a transformer.

[0061] When coil component 1F is mounted on a circuit board, conductor 2a (input terminal) is electrically connected to an input electrode (not shown) on the circuit board, and conductor 2g (output terminal) is electrically connected to an output electrode (not shown) on the circuit board. In addition, conductor 2d is electrically connected to an intermediate electrode (not shown) on the circuit board and functions as an intermediate terminal of coil component 1F that connects the first coil L1 and the second coil L2 in series.

[0062] When the conductor 2a (input terminal) of the first coil L1 of coil component 1F is connected to a power source, current flows clockwise from conductor 2a to conductor 2b, conductor 2c, and conductor 2d, as viewed from the top surface 40A side. Similarly, when viewed from the top surface 40A side, current flows clockwise from the intermediate terminal conductor 2d of the second coil L2 of coil component 1F to conductor 2e, conductor 2f, and conductor 2g (output terminal). As a result, the first coil L1 and the second coil L2 generate a magnetic field in the direction from the top surface 40A to the bottom surface 40B (-Z direction).

[0063] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope of the claims are intended to be included.

[0064] 1, 1A to 1E Coil components, 2, 20, 30, 30A Metal conductors, 4 Housing, 40A Top surface, 40B Bottom surface, 41, 42, 43, 44 Side surfaces, 50 Capacitor, 50A Capacitor, 50B Inductor, 100 Filter circuit, L1 First coil, L2 Second coil.

Claims

1. A coil component comprising a metal conductor constituting at least two or more turns of a coil, and a resin member covering the metal conductor, wherein a portion of one end of the metal conductor is an input terminal, a portion of the other end of the metal conductor is an output terminal, and a portion of the middle part of the metal conductor is an intermediate terminal, and a first coil formed between the input terminal and the intermediate terminal and a second coil formed between the output terminal and the intermediate terminal are magnetically coupled to each other to form a transformer, and at least the input terminal, the output terminal and the intermediate terminal are exposed on the same surface of the resin member.

2. The coil component according to claim 1, wherein in the input terminal, the output terminal, and the intermediate terminal, a portion of the metal conductor greater than or equal to the plate thickness is exposed from the resin member.

3. The coil component according to claim 1 or claim 2, wherein the resin member is a mixed material of resin and magnetic material.

4. The coil component according to any one of claims 1 to 3, wherein the coil made of the metal conductor has one winding axis.

5. The coil component according to any one of claims 1 to 3, wherein the coil made of the metal conductor has a plurality of winding shafts.

6. The coil component according to any one of claims 1 to 5, wherein the opening surface of the coil made of the metal conductor is perpendicular to the surface of the resin member on which the input terminal, the output terminal, and the intermediate terminal are exposed.

7. The coil component according to any one of claims 1 to 5, wherein the opening surface of the coil made of the metal conductor is parallel to the surface of the resin member on which the input terminal, the output terminal, and the intermediate terminal are exposed.

8. The coil component according to any one of claims 1 to 7, wherein the shape of the coil made of the metal conductor as viewed from the winding shaft is circular.

9. The coil component according to any one of claims 1 to 7, wherein the shape of the coil made of the metal conductor as viewed from the winding shaft is rectangular.

10. The coil component according to any one of claims 1 to 6, wherein the metal conductor has a branching portion that branches into a first conductor and a second conductor shorter than the first conductor, and the end of the second conductor constitutes the intermediate terminal.

11. The coil component according to any one of claims 1 to 10, wherein the resin member is a molded resin material.

12. The coil component according to any one of claims 1 to 10, wherein the resin member is a dip-molded resin material.

13. An electronic device comprising the coil component described in any one of claims 1 to 12.

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