Coil component and filter circuit including same

Abstract

The present disclosure provides a coil component having a structure in which negative inductance caused by the magnetic coupling of two coils does not decrease, and a filter circuit including the coil component. A coil component (1) according to the present disclosure comprises: a housing (4) that includes a pair of a principal surface (40A) and a principal surface (40B) that face each other, and four side surfaces (41-44) that join the principal surface (40A) and the principal surface (40B); a coil (L1) disposed inside the housing (4); and a coil (L2) disposed inside the housing (4) so that the opening thereof overlaps the opening of the coil (L1) when viewed in the direction from the principal surface (40A). A led-out line (2d) extends in the direction of the principal surface (40B) along the side of the side surface (41). A led-out line (3d) extends in the direction of the principal surface (40B) along the side of the side surface (42).

Description

Coil components and filter circuits including them

[0001] The present disclosure relates to a coil component and a filter circuit including the same.

[0002] In electronic devices, noise suppression using filter circuits is often used. Examples of filter circuits used for noise suppression include EMI (Electro-Magnetic Interference) filters, which allow necessary components of the current flowing through a conductor to pass through, while removing unnecessary components. Furthermore, because filter circuits use capacitors, which are capacitance elements, it is known that the noise suppression effect is reduced by the equivalent series inductance (ESL), which is the parasitic inductance of the capacitor.

[0003] A technique is known for broadening the bandwidth of the noise suppression effect of a filter circuit by canceling the equivalent series inductance ESL of a capacitor with the negative inductance generated by magnetically coupling two coils (see, for example, Japanese Patent Laid-Open No. 2001-160728: Patent Document 1). Also known is a coil component having a structure in which two coils made by bending a metal plate are stacked vertically (see, for example, Japanese Patent Laid-Open No. 2004-296630: Patent Document 2).

[0004] JP 2001-160728 A JP 2004-296630 A

[0005] When a coil component having the structure described in JP 2004-296630 A (Patent Document 2) is used in a filter circuit, the coil component is used as a three-terminal transformer coil, with the portion connecting the two coils serving as an intermediate terminal. When the coil component is used as a three-terminal transformer coil, it is necessary to extend wiring from the intermediate terminal to the mounting surface, which generates positive parasitic inductance in the wiring. When the coil component is used in a filter circuit, the positive parasitic inductance generated in the wiring cancels out part of the negative inductance generated by magnetically coupling the two coils, resulting in a problem of reducing the negative inductance of the coil component.

[0006] Therefore, an object of the present disclosure is to provide a coil component having a structure that does not reduce the negative inductance that occurs when two coils are magnetically coupled, and a filter circuit that includes the coil component.

[0007] A coil component according to one embodiment of the present disclosure includes a housing having a pair of opposing first and second main surfaces and four side surfaces connecting the first and second main surfaces, a first coil disposed inside the housing and substantially parallel to the first main surface, and a second coil disposed inside the housing such that an opening of the first coil overlaps an opening of the second coil when viewed from the first main surface. The first coil is connected to first and second lead wires drawn from a first side surface of the housing, and the second coil is connected to third and fourth lead wires drawn from a second side surface different from the first side surface. The second lead wire of the first coil extends toward the second main surface along the first side surface, and the fourth lead wire of the second coil extends toward the second main surface along the second side surface.

[0008] A filter circuit according to an embodiment of the present disclosure includes the above-described coil component and a capacitor electrically connected to the second lead wire and the fourth lead wire of the coil component.

[0009] According to one embodiment of the present disclosure, the second lead wire of the first coil extends in the direction of the second main surface along the first side surface side from which it is drawn out, and the fourth lead wire of the second coil extends in the direction of the second main surface along the second side surface side from which it is drawn out, so that it is possible to form a coil using the second lead wire and the fourth lead wire, and the negative inductance generated by magnetically coupling the two coils is not reduced.

[0010] FIG. 1 is a perspective view of a coil component according to a first embodiment; FIG. 2 is a circuit diagram of a filter circuit including the coil component according to the first embodiment; FIG. 3 is a diagram for explaining a change in mutual inductance due to the shape of an intermediate terminal; FIG. 4 is a diagram for explaining a change in mutual inductance due to the shape of a housing; FIG. 5 is a perspective view of a coil component according to a second embodiment; FIG. 6 is a diagram for explaining the positional relationship of opening surfaces of a coil; FIG. 7 is a perspective view of a coil component according to a first modification; FIG. 8 is a perspective view of a coil component according to a second modification; FIG. 9 is an exploded plan view showing the configuration of a coil component according to a third modification.

[0011] Hereinafter, a coil component according to this embodiment and a filter circuit including the coil component will be described with reference to the drawings.

[0012] First Embodiment First, a coil component according to the first embodiment will be described with reference to the drawings. Fig. 1 is a perspective view of the coil component 1 according to the first embodiment. Fig. 2 is a circuit diagram of a filter circuit 100 including the coil component 1 according to the first embodiment. Note that with respect to the X-axis, Y-axis, and Z-axis defined in Fig. 1, the X-axis direction represents the left-right direction of the coil component 1, the Y-axis direction represents the front-rear direction of the coil component 1, and the Z-axis direction represents the up-down direction of the coil component 1, respectively.

[0013] The coil component 1 is, for example, a transformer coil mounted in a filter circuit 100 used to suppress noise in a power line. As will be described later, the coil component 1 magnetically couples two coils to cancel the parasitic inductance of a capacitor mounted in the filter circuit 100. Furthermore, the coil component 1 employs a structure in which the lead wires of the two coils are used to form a third coil.

[0014] The coil component 1 includes a coil portion 2a (first coil) and a coil portion 3a (second coil) housed within a housing 4. Hereinafter, the coil portion 2a will also be referred to as coil L1, and the coil portion 3a will also be referred to as coil L2. The coil portion 2a has one end connected to a lead wire 2b (first lead wire) and the other end connected to a lead wire 2d (second lead wire). The coil portion 3a has one end connected to a lead wire 3b (third lead wire) and the other end connected to a lead wire 3d (fourth lead wire). The coil portion 2a and the lead wires 2b and 2d are formed of a single conductor, such as a metal plate or metal wire made of copper or an alloy of copper and other metals. Similarly, the coil portion 3a and the lead wires 3b and 3d are also formed of a single conductor. The coils L1 and L2, formed from metal plates, are covered with an insulating material (not shown). Specifically, the insulating material covering the coils L1 and L2 is a resin such as polyimide or epoxy. It is not necessary for the insulating material to cover all surfaces of the coils L1 and L2. In order to prevent contact between the coils L1 and L2, it is sufficient that the insulating material is provided at least on the surfaces where the coils L1 and L2 face each other.

[0015] The coil portion 2a has a rectangular opening and is disposed inside the housing 4 substantially parallel to the main surface 40A (first main surface). Although the coil portion 2a is illustrated as a single-turn coil, it may be a multi-turn coil. The lead wire 2d and the lead wire 2d are drawn out from the side surface 41 (first side surface) of the housing 4 and extend along the side surface 41 toward the main surface 40B (second main surface). The lead wire 2b shown in FIG. 1 extends to the main surface 40B, with the portion of the lead wire 2b that contacts the main surface 40B constituting the end 2c. The lead wire 2d also extends to the main surface 40B, with the portion of the lead wire 2d that contacts the main surface 40B constituting the end 2e. When the coil component 1 is mounted on a substrate, the end 2c is electrically connected to wiring on the substrate.

[0016] The coil portion 3a has a rectangular opening and is disposed above the coil portion 2a inside the housing 4, approximately parallel to the main surface 40A. Although the coil portion 3a is illustrated as a single-turn coil, it may be a multi-turn coil. The lead wires 3d and 3d are drawn out from the side surface 42 (second side surface) of the housing 4 and extend along the side surface 42 toward the main surface 40B. The lead wire 3b shown in FIG. 1 extends to the main surface 40B, with the portion of the lead wire 3b that contacts the main surface 40B constituting the end 3c. The lead wire 3d extends to the main surface 40B, with the portion of the lead wire 3d that contacts the main surface 40B constituting the end 3e. When the coil component 1 is mounted on a substrate, the end 3c is electrically connected to wiring on the substrate. The end 2e and end 3e are electrically connected by a connecting member 5 disposed on the main surface 40B. By connecting end 2e and end 3e with connecting member 5, coil L1 and coil L2 are connected in series, and ends 2e, 3e and connecting member 5 form an intermediate terminal T between coil L1 and coil L2.

[0017] Coil L1 and coil L2 are disposed inside housing 4 closer to main surface 40A than to main surface 40B. Preferably, coil L1 and coil L2 are disposed closer to main surface 40A than to the midpoint between main surfaces 40A and 40B. This allows the length of lead wire 2d extending from the other end of coil portion 2a to main surface 40B and the length of lead wire 3d extending from the other end of coil portion 3a to main surface 40B to be increased, thereby allowing the opening of the coil (coil L3) formed by lead wire 2d, lead wire 3d, and connecting member 5 to be increased.

[0018] When the end 2c of the coil portion 2a (coil L1) is connected to a power source, a current flows clockwise from the lead wire 2b. The current that flows through the coil portion 2a flows counterclockwise through the lead wire 2d, the connecting member 5, and the lead wire 3d in that order. A current flows clockwise from the lead wire 3d in the coil portion 3a (coil L2). Therefore, a magnetic field is generated in the coil portion 2a in the direction from the main surface 40A to the main surface 40B (-Z direction). A magnetic field is also generated in the coil portion 3a in the direction from the main surface 40A to the main surface 40B (-Z direction). Since the coil portions 2a and 3a are arranged so as to overlap when viewed from the main surface 40A, the coils L1 and L2 are magnetically coupled. The coil (coil L3) formed by the lead wire 2d, the lead wire 3d, and the connecting member 5 generates a magnetic field in the +X direction. Although FIG. 1 shows an example in which the openings almost overlap, the openings may be offset from each other as long as they are within the range of magnetic field coupling, and it is sufficient that 50% or more of each opening overlaps.

[0019] The housing 4 fixes the relative positions of the coil L1 and the coil L2 and is made of, for example, molded resin. Specifically, the molded resin is made of epoxy resin with silica filler, silicone resin, liquid crystal polymer, or various resins containing a metallic magnetic material. The housing 4 has a side surface 41 (first side surface) and a side surface 42 (second side surface) that face each other. The side surface closer to the lead wire 2b (first lead wire) is called a side surface 43 (third side surface), and the side surface closer to the lead wire 2d (second lead wire) is called a side surface 44 (fourth side surface). While FIG. 1 shows the housing 4 in a rectangular parallelepiped shape, the side surfaces may be inclined as long as the second main surface, which serves as the mounting surface, and the coil surface are substantially parallel. For example, the housing 4 may be a trapezoid in which the area of ​​the second main surface is greater than that of the first main surface.

[0020] The filter circuit 100 is, for example, an EMI filter, as shown in FIG. 2 , and is a third-order T-type LC filter circuit. The filter circuit 100 has its terminal 2c connected to a power supply (not shown) and its terminal 3c connected to a circuit (not shown), such as a DC / DC converter or a power supply module. The filter circuit 100 passes necessary components of the current flowing from the power supply to the circuit and removes unnecessary components. Specifically, a direct current (DC) is passed through the filter circuit 100, and high-frequency noise contained in the DC current is dropped to GND via a capacitor C1. The capacitor C1, which is a capacitance element, has an equivalent series inductance (ESL) (La) of the capacitor C1, which prevents high-frequency noise from passing through, thereby degrading noise removal performance. The filter circuit 100 maintains high noise removal performance by canceling the ESL (La) of the capacitor C1 using the negative inductance generated by the magnetic coupling between the two coils. In this disclosure, the negative inductance generated in series with the capacitor C1 is referred to as the mutual inductance M of the coil component 1.

[0021] In the following embodiments, a third-order T-type LC filter circuit will be used as the configuration of the filter circuit 100, but coil components of a similar configuration can also be applied to a fifth-order T-type LC filter circuit or a higher-order T-type LC filter circuit. As shown in Figure 2, the filter circuit 100 includes a capacitor C1, ends 2c and 3c, an intermediate terminal T (ends 2e and 3e, and a connecting member 5), a coil L1, and a coil L2.

[0022] As shown in FIG. 2, one end of the capacitor C1 is connected to the intermediate terminal T, and the other end is connected to the GND wiring. The capacitor C1 is made of BaTiO ３The present invention is not limited to multilayer ceramic capacitors primarily composed of barium titanate (barium titanate), but may also include multilayer ceramic capacitors primarily composed of other materials, or other types of capacitors other than multilayer ceramic capacitors, such as aluminum electrolytic capacitors. Capacitor C1 has an inductor La as a parasitic inductance (equivalent series inductance (ESL)), and is equivalent to a circuit configuration in which inductor La is connected in series with capacitor C1a. Capacitor C1 may also be equivalent to a circuit configuration in which parasitic resistance (equivalent series resistance (ESR)) is connected in series with inductor La and capacitor C1a.

[0023] In addition to capacitor C1, coils L1 and L2 are also connected to intermediate terminal T. Coils L1 and L2 are magnetically coupled and have a mutual inductance M. A negative inductance component equal in magnitude to the mutual inductance M is generated between intermediate terminal T and capacitor C1. This negative inductance component can be used to cancel out the parasitic inductance (inductor La) of capacitor C1, thereby making the parasitic inductance component of capacitor C1 appear smaller. In other words, filter circuit 100, which is composed of capacitor C1, coil L1, and coil L2, cancels out the parasitic inductance of capacitor C1 with the negative inductance component due to the mutual inductance between coils L1 and L2, thereby preventing a decrease in the noise suppression effect in the high frequency band due to the parasitic inductance of capacitor C1 and improving the noise suppression effect of filter circuit 100.

[0024] However, in the case of a three-terminal coil component in which the part connecting coils L1 and L2 is intermediate terminal T, if a wire is drawn from intermediate terminal T and connected to capacitor C1, a positive parasitic inductance will occur in the wire. When this coil component is used in a filter circuit, the positive parasitic inductance occurring in the wire reduces the negative inductance component due to the mutual inductance between coils L1 and L2, making it impossible to fully cancel out the parasitic inductance of capacitor C1, thereby reducing the noise suppression effect in the high frequency band.

[0025] Therefore, in the coil component 1 according to the first embodiment, instead of simply drawing out a wire from the intermediate terminal T connecting the coils L1 and L2 and connecting it to the capacitor C1, as shown in FIG. 1 , a coil (coil L3) is formed using the lead wires 2d and 3d and a connecting member 5 and connected to the capacitor C1. Specifically, the coil L3 is electrically connected to the wiring on the board by the connecting member 5, and is connected to the capacitor C1, which is electrically connected to the same wiring. In the coil component 1, the coil L3 itself, which is connected to the capacitor C1, is also coupled as part of the coils L1 and L2, and therefore contributes to the negative inductance component due to the mutual inductance between the coils L1 and L2, and does not reduce the negative inductance component. Instead of the connecting member 5, the end 2e connected to the lead wire 2d or the end 3e connected to the lead wire 3d may be connected to the wiring on the board.

[0026] Furthermore, the intermediate terminal T, which connects coil L1 and coil L2, is a coil (coil L3) composed of lead wire 2d, lead wire 3d, and connecting member 5, so the three coils L1 to L3 have a positive coupling coefficient. While the connecting member 5 has been described as being disposed on main surface 40B in coil component 1, the connecting member 5 may also be provided on the substrate on which coil component 1 is mounted. That is, the coil component 1 itself does not constitute a coil (coil L3) because lead wire 2d and lead wire 3d are not electrically connected. However, a coil (coil L3) may be formed by mounting coil component 1 on a substrate provided with connecting member 5. Even in the case of a coil component 1 that does not include connecting member 5, mounting it on a substrate provided with connecting member 5 eliminates the need to draw a wire from intermediate terminal T and connect it to capacitor C1. This eliminates the need to draw a wire from capacitor C1, thereby preventing the negative inductance component due to the mutual inductance between coil L1 and coil L2 from being reduced by the wire.

[0027] FIG. 3 is a diagram illustrating the change in mutual inductance depending on the shape of the intermediate terminal. FIG. 3(a) is a schematic diagram illustrating the shape of the intermediate terminal of the coil component 1. In FIG. 3(a), the intermediate terminal T connected to the capacitor C1 (not shown) is shaped as a coil L3, and therefore the inductance component of coil L3 is added to the transformer coil formed by coils L1 and L2. This increases the mutual inductance M of the coil component 1. Specifically, if the size of the coil component 1 is 2.5 × 2.0 × 1.5 mm and the inductance values ​​of coils L1 and L2 are approximately 3 nH, the simulated value of the mutual inductance M of the coil component 1 is M = −1.024 nH.

[0028] On the other hand, Figure 3(b) is a schematic diagram showing a configuration in which a wiring 6 is extended from an intermediate terminal T in a comparative coil component 11 and connected to a capacitor C1 (not shown). In Figure 3(b), the wiring 6 for connection to the capacitor C1 has a positive parasitic inductance, which is canceled out by the mutual inductance M between the coils L1 and L2, resulting in a low mutual inductance M of the coil component 11. Specifically, if the inductance values ​​of the coils L1 and L2 are the same as those of the coil component 1 shown in Figure 3(a) and the length of the wiring 6 is 1.0 mm, the simulated value of the mutual inductance M of the coil component 11 is M = -0.24 nH.

[0029] The size of the opening of the coil L3 varies depending on the shape of the housing 4, and therefore the mutual inductance M of the coil component also varies. FIG. 4 is a diagram illustrating the change in mutual inductance M due to the shape of the housing. FIG. 4( a) is a perspective view of a coil component 1A in which coils L1 and L2 are enclosed in a rectangular housing 4A whose main surface 40A has long sides 4L and short sides 4W. In the coil component 1A, the lead wires 2b and 2d and the lead wires 3b and 3d are drawn out from the side surface on the short side 4W side. Therefore, in the coil component 1A, the side surface on the long side 4L side forms the opening for the coil L3. Specifically, when the housing 4A has long sides 4L = 2.5 mm, short sides 4W = 2.0 mm, and a height 4H = 1.5 mm, and the distance between the coils L1 and L2 is 0.02 mm, the simulated value of the mutual inductance M of the coil component 1A is M = -1.12 nH.

[0030] 4(b) is a perspective view of a coil component 1B in which lead wires 2b, 2d and lead wires 3b, 3d are drawn out from the side surface of the housing 4A on the long side 4L side. In the coil component 1B, lead wires 2b, 2d and lead wires 3b, 3d are drawn out from the side surface of the housing 4A on the long side 4L side. Therefore, in the coil component 1B, the side surface on the short side 4W side serves as the opening for the coil L3. Specifically, the opening for the coil L3 is smaller in the coil component 1B than in the coil component 1A, so the simulated value of the mutual inductance M of the coil component 1B is M = -1.06 nH. The size of the coil component 1B and the spacing between the coils L1 and L2 are the same as those of the coil component 1A shown in FIG. 4(a).

[0031] 4(c) is a perspective view of a coil component 1C in which coils L1 and L2 are housed in a housing 4B having a shorter height 4H than that of the housing 4A. In the coil component 1C, leads 2b and 2d and leads 3b and 3d are drawn out from the side surface of the short side 4W. Therefore, in the coil component 1C, the side surface of the long side 4L forms the opening for the coil L3. Specifically, when the housing 4B has a long side 4L of 2.5 mm, a short side 4W of 2.0 mm, and a height 4H of 0.9 mm, and the distance between the coils L1 and L2 is 0.02 mm, the simulated value of the mutual inductance M of the coil component 1C is M = -0.81 nH.

[0032] FIG. 4( d ) is a perspective view of a coil component 1D in which lead wires 2b, 2d and lead wires 3b, 3d are drawn out from the side surface of the housing 4B on the long side 4L side. In the coil component 1D, lead wires 2b, 2d and lead wires 3b, 3d are drawn out from the side surface of the housing 4B on the long side 4L side. Therefore, in the coil component 1D, the side surface on the short side 4W side serves as the opening for the coil L3. Specifically, the opening for the coil L3 is smaller in the coil component 1D than in the coil component 1C, but the shorter height 4H reduces the effect on the mutual inductance M, and the simulated value of the mutual inductance M for the coil component 1D is M=−0.81 nH. The size of the coil component 1D and the spacing between the coils L1 and L2 are the same as those of the coil component 1C shown in FIG. 4( c ).

[0033] As described above, the coil component 1 according to the first embodiment includes a housing 4 having a pair of opposing main surfaces 40A and 40B and four side surfaces 41 to 44 connecting the main surfaces 40A and 40B, a coil L1 disposed inside the housing 4 and substantially parallel to the main surface 40A, and a coil L2 disposed inside the housing 4 such that the openings of the coil L1 overlap when viewed from the direction of the main surface 40A. The coil L1 has lead wires 2b and 2d drawn out from the side surface 41 of the housing 4. The coil L2 has lead wires 3b and 3d drawn out from the side surface 42, which is different from the side surface 41. The lead wire 2d extends along the side surface 41 toward the main surface 40B. The lead wire 3d extends along the side surface 42 toward the main surface 40B. Note that in this specification, "extending along the side surface" means "extending substantially parallel to the side surface."

[0034] As a result, in the coil component 1 according to the first embodiment, the lead wire 2d of the coil L1 extends in the direction of the main surface 40B along the side surface 41 where it is drawn out, and the lead wire 3d of the coil L2 extends in the direction of the main surface 40B along the side surface 42 where it is drawn out, so that it is possible to configure a coil with the lead wires 2d and 3d, and there is no reduction in the negative inductance that occurs when the two coils L1 and L2 are magnetically coupled. In particular, by forming the lead wires 2d and 3d along the opposing side surfaces 41 and 42, respectively, it is possible to widen the opening of the coil L3, and it is possible to increase the value of the mutual inductance M without changing the size of the housing.

[0035] In coil component 1, lead wires 2b and 2d are drawn out from the side surface 41 to the outside of housing 4. However, as long as lead wires 2b and 2d are drawn out from the side surface 41, coil component 1 does not need to be drawn out to the outside of housing 4, and lead wires 2b and 2d may be located inside housing 4. Similarly, in coil component 1, lead wires 3b and 3d are drawn out from the side surface 42 to the outside of housing 4. However, as long as lead wires 3b and 3d are drawn out from the side surface 42, coil component 1 does not need to be drawn out to the outside of housing 4, and lead wires 3b and 3d may be located inside housing 4.

[0036] The filter circuit 100 according to the first embodiment includes the coil component 1 described above, and a capacitor C1 electrically connected to intermediate terminals (lead wires 2d and 3d) between the coil L1 and coil L2 of the coil component 1. This allows the filter circuit 100 to sufficiently cancel out the parasitic inductance of the capacitor C1 with the negative inductance generated by magnetically coupling the two coils L1 and L2, thereby achieving a wide-band noise suppression effect.

[0037] <Embodiment 2> In embodiment 1, it has been described that the coil (coil L3) is configured by the lead wires 2d, 3d, and connecting member 5 of coil component 1. In embodiment 2, the orientation of the opening surface of the coil (coil L3) will be described in detail. FIG. 5 is a perspective view of coil component 1E according to embodiment 2. Note that in coil component 1E shown in embodiment 2, the same components as those in coil component 1 according to embodiment 1 are designated by the same reference numerals and detailed description will not be repeated. Furthermore, coil component 1E shown in embodiment 2 can be applied to filter circuit 100 according to embodiment 1 in place of coil component 1 according to embodiment 1.

[0038] 5, in coil device 1E, lead wires 2d and 3d extend substantially straight from their respective lead positions toward main surface 40B. Therefore, the opening of coil L3, which is formed by lead wires 2d and 3d and connecting member 5, is perpendicular (90 degrees) to the openings of coils L1 and L2.

[0039] The side surface 41 (first side surface) and the side surface 42 (second side surface) of the housing 4 face each other, and the side surface closer to the lead wire 2b (first lead wire) is referred to as the side surface 43 (third side surface), and the side surface closer to the lead wire 2d (second lead wire) is referred to as the side surface 44 (fourth side surface). The lead wires 2b and 2d are drawn out from the side surface 41 on the side surface 44 side. The lead wires 3b and 3d are drawn out from the side surface 42 on the side surface 44 side. In other words, the coil device 1E is enclosed in the housing 4 with the lead wires 2b and 2d, and the lead wires 3b and 3d, drawn out from the coil portions 2a and 3a, respectively, positioned closer to the side surface 44. Here, the state in which the lead wires 2b and 2d are closer to the side surface 44 means that the region between the connection point between the coil portion 2a and the lead wire 2b and the connection point between the coil portion 2a and the lead wire 2d is located closer to the side surface 44 than the midpoint between the side surfaces 43 and 44.

[0040] Furthermore, the end of lead wire 2d on the main surface 40B side is located on side surface 41 on the side surface 44 side. Specifically, when viewed from the direction in which end portions 2e, 3e, and the connecting member 5 extend (the Y-axis direction), lead wire 2d is drawn out from a position within the width of end portion 2e. The end of lead wire 3d on the main surface 40B side is located on side surface 42 on the side surface 44 side. Specifically, when viewed from the Y-axis direction, lead wire 3d is drawn out from a position within the width of end portion 3e. In other words, lead wires 2d and 3d are substantially straight lines extending from their drawn-out positions toward the main surface 40B side. Therefore, the coil (coil L3) formed by lead wires 2d, 3d, and connecting member 5 is formed parallel to the side surface 44.

[0041] 1 , in coil device 1, lead wires 2b and 2d are drawn out from an intermediate portion of side surface 41 sandwiched between side surfaces 43 and 44, and lead wires 3b and 3d are drawn out from an intermediate portion of side surface 42 sandwiched between side surfaces 43 and 44. That is, in coil device 1, coil portions 2a and 3a are contained within housing 4 midway between side surfaces 43 and 44, and lead wires 2b and 2d, as well as lead wires 3b and 3d, are also drawn out from intermediate portions of the side surfaces sandwiched between side surfaces 43 and 44. Here, being drawn out from an intermediate portion means that a point in the region sandwiched between the connection point of coil portion 2a and lead wire 2b and the connection point of coil portion 2a and lead wire 2d overlaps the intermediate position between side surfaces 43 and 44.

[0042] Furthermore, the end of lead wire 2d on the main surface 40B side is on side surface 41 on the side surface 44 side. The end of lead wire 3d on the main surface 40B side is on side surface 42 on the side surface 44 side. In other words, lead wires 2d and 3d extend obliquely from their drawn-out positions toward the side surface 44 side toward the main surface 40B side. Therefore, the coil (coil L3) formed by lead wires 2d, 3d and connecting member 5 is formed inclined with respect to the side surface 44. The opening surface of coil L3 is inclined at an angle greater than 90 degrees with respect to the opening surfaces of coils L1 and L2.

[0043] A schematic diagram will be used to clearly explain the positional relationship between the opening surface of coil L3 and the opening surfaces of coils L1 and L2. FIG. 6 is a diagram for explaining the positional relationship between the opening surfaces of the coils. FIG. 6(a) is a schematic diagram showing the positional relationship between the opening surface of coil L3 and the opening surfaces of coils L1 and L2 of coil component 1E. In coil component 1E, coils L1 and L2 are arranged parallel to the X-Y plane, and coil L3 is arranged parallel to the Y-Z plane. In coil component 1E, the angle θ between the direction of magnetic field G1 generated by coils L1 and L2 and the direction of magnetic field G2 generated by coil L3 is 90 degrees.

[0044] 6(b) is a schematic diagram showing the positional relationship between the open surface of coil L3 and the open surfaces of coils L1 and L2 of coil component 1. In coil component 1, coils L1 and L2 are arranged parallel to the X-Y plane, and coil L3 is arranged tilted in the X direction from a position parallel to the Y-Z plane. In coil component 1, the angle θ between the direction of magnetic field G1 generated by coils L1 and L2 and the direction of magnetic field G2 generated by coil L3 is greater than 90 degrees.

[0045] When the angle θ between the direction of magnetic field G1 and the direction of magnetic field G2 is greater than 90 degrees, as in coil component 1, the direction of magnetic field G2 includes a directional component opposite to the direction of magnetic field G1, reducing the coupling coefficient between the three coils L1 to L3. Therefore, by setting the angle θ between the direction of magnetic field G1 and the direction of magnetic field G2 to 90 degrees, as in coil component 1E, the directional component opposite to the direction of magnetic field G1 in the direction of magnetic field G2 can be reduced, thereby increasing the coupling coefficient between the three coils L1 to L3. By increasing the coupling coefficient between the three coils L1 to L3, coil component 1E contributes to the negative inductance component due to the mutual inductance between coil L1 and coil L2, without reducing this negative inductance component.

[0046] (Variation 1) In the coil component 1E, as shown in FIG. 5 , the coil portions 2a and 3a are positioned closer to the side surface 44 and enclosed within the housing 4, thereby positioning the coil L3 so that the angle θ between the direction of the magnetic field G1 and the direction of the magnetic field G2 is 90 degrees. However, the coil L3 can be positioned so that the angle θ between the direction of the magnetic field G1 and the direction of the magnetic field G2 is 90 degrees even if the coil portions 2a and 3a are not positioned closer to the side surface 44. FIG. 7 is a perspective view of a coil component 1F according to Variation 1. Note that in the coil component 1F shown in Variation 1, the same components as those in the coil component 1 according to embodiment 1 are designated by the same reference numerals, and detailed description thereof will not be repeated. Furthermore, the coil component 1F shown in Variation 1 can be applied to the filter circuit 100 according to embodiment 1 in place of the coil component 1 according to embodiment 1.

[0047] 7, in the coil device 1F, the lead wires 2d and 3d extend straight from their respective lead positions toward the main surface 40B. Therefore, the opening of the coil (coil L3) formed by the lead wires 2d and 3d and the connecting member 5 is perpendicular (90 degrees) to the openings of the coils L1 and L2.

[0048] 7, in coil device 1F, lead wires 2b and 2d are drawn out from an intermediate portion of side surface 41 sandwiched between side surfaces 43 and 44, and lead wires 3b and 3d are drawn out from an intermediate portion of side surface 42 sandwiched between side surfaces 43 and 44. In other words, in coil device 1F, similar to coil device 1 shown in FIG. 1, coil portions 2a and 3a are contained within housing 4 midway between side surfaces 43 and 44, and lead wires 2b and 2d and lead wires 3b and 3d are also drawn out from intermediate portions of the side surfaces sandwiched between side surfaces 43 and 44.

[0049] Furthermore, in coil device 1F, the end of lead wire 2d on the main surface 40B side is located in the middle of side surface 41 between side surfaces 43 and 44, and the end of lead wire 3d on the main surface 40B side is located in the middle of side surface 42 between side surfaces 43 and 44. In other words, lead wires 2d and 3d are straight lines extending toward main surface 40B from their respective drawn-out positions. Therefore, the coil (coil L3) formed by lead wires 2d, 3d, and connecting member 5 is formed parallel to side surface 44.

[0050] In the coil component 1F, the opening surface of the coil L3 is perpendicular (90 degrees) to the opening surfaces of the coils L1 and L2 at the centers of the coils L1 and L2. On the other hand, in the coil component 1E, as shown in Fig. 5, the opening surface of the coil L3 is perpendicular (90 degrees) to the opening surfaces of the coils L1 and L2 at the ends of the coils L1 and L2. Therefore, the coupling coefficient of the three coils L1 to L3 can be made higher in the coil component 1E than in the coil component 1F.

[0051] (Modification 2) In the coil component 1, as shown in FIG. 6( a), the coil L3 is arranged so that the angle θ between the direction of the magnetic field G1 and the direction of the magnetic field G2 is greater than 90 degrees. In the coil component 1E, as shown in FIG. 6( b), the coil L3 is arranged so that the angle θ between the direction of the magnetic field G1 and the direction of the magnetic field G2 is 90 degrees. In the coil component according to Modification 2, the coil L3 is arranged so that the angle θ between the direction of the magnetic field G1 and the direction of the magnetic field G2 is less than 90 degrees. FIG. 8 is a perspective view of the coil component 1G according to Modification 2. Note that in the coil component 1G shown in Modification 2, the same components as those in the coil component 1 according to embodiment 1 are designated by the same reference numerals, and detailed description thereof will not be repeated. Furthermore, the coil component 1G shown in Modification 2 can be applied to the filter circuit 100 according to embodiment 1 in place of the coil component 1 according to embodiment 1.

[0052] 8, in the coil device 1G, the lead wires 2d and 3d extend obliquely from the lead positions toward the main surface 40B side. Therefore, the opening plane of the coil (coil L3) formed by the lead wires 2d and 3d and the connecting member 5 is angled at an angle of less than 90 degrees with the opening planes of the coils L1 and L2.

[0053] Lead wire 2b is drawn out from side surface 41 on the side surface 43 side. Lead wire 2d is drawn out from side surface 43 further toward side surface 41 than lead wire 2b, passing through the inside of housing 4. Similarly, lead wire 3b is drawn out from side surface 42 on the side surface 43 side. Lead wire 3d is drawn out from side surface 43 further toward side surface 42 than lead wire 3b, passing through the inside of housing 4. In other words, lead wires 2b and 3b are drawn out to the outside of housing 4, and lead wires 2d and 3d are drawn into housing 4. Lead wires 2b and 2d intersect midway, and lead wires 3b and 3d intersect midway.

[0054] Furthermore, the end of lead wire 2d on the main surface 40B side is on the side surface 41 side of the side surface 44. The end of lead wire 3d on the main surface 40B side is on the side surface 42 side of the side surface 44. In other words, lead wires 2d and 3d extend obliquely from their drawn-out positions toward the side surface 44 toward the main surface 40B. The ends of lead wires 2d and 3d are electrically connected via a connecting member 5a disposed inside the housing 4. Therefore, the coil (coil L3) formed by lead wires 2d, 3d, and connecting member 5a is formed inclined with respect to the side surface 44. The opening surface of coil L3 is inclined at an angle of less than 90 degrees with respect to the opening surfaces of coils L1 and L2.

[0055] A schematic diagram will be used to clearly explain the positional relationship between the opening surface of coil L3 and the opening surfaces of coils L1 and L2. FIG. 9 is a diagram for explaining the positional relationship between the opening surfaces of coils according to Modification 2. FIG. 9 is a schematic diagram showing the positional relationship between the opening surface of coil L3 and the opening surfaces of coils L1 and L2 of coil component 1G. In coil component 1G, coils L1 and L2 are arranged parallel to the X-Y plane, and coil L3 is arranged tilted in the X direction from a position parallel to the Y-Z plane. In coil component 1G, the angle θ between the direction of magnetic field G1 generated by coils L1 and L2 and the direction of magnetic field G2 generated by coil L3 is smaller than 90 degrees.

[0056] When the angle θ between the directions of magnetic fields G1 and G2 is less than 90 degrees, as in coil component 1G, the direction of magnetic field G2 includes a directional component that is oriented in the same direction as magnetic field G1, and the coupling coefficient among the three coils L1 to L3 increases. Therefore, by making the angle θ between the directions of magnetic fields G1 and G2 less than 90 degrees, as in coil component 1G, the number of directional components in the direction of magnetic field G2 that are oriented in the same direction as magnetic field G1 can be increased, and the coupling coefficient among the three coils L1 to L3 can be increased.

[0057] (Variation 3) In the coil components according to the embodiments and variations described so far, the coil portion 2 a and the lead wires 2 b, 2 d are formed from a single conductor (e.g., a metal plate), and the coil portion 3 a and the lead wires 3 b, 3 d are also formed from a single conductor. Furthermore, in these coil components, the coil portion 2 a and the coil portion 3 a, both formed from conductors, are fixed with the molding resin of the housing 4 at a position where they overlap, and the lead wires 2 b, 2 d, 3 b, 3 d drawn from the side surface of the housing 4 are bent along the side surface of the housing 4. However, the manufacturing method of the coil component is not limited to the above-described method. In Variation 3, a coil component will be described in which the coil is not formed from a single conductor, but is manufactured by stacking multiple substrates (ceramic green sheets) on which coil wiring is formed.

[0058] 10 is an exploded plan view showing the configuration of a coil component according to Modification 3. Note that in the coil component shown in Modification 3, the same components as those in coil component 1 according to embodiment 1 are designated by the same reference numerals and detailed description thereof will not be repeated. Furthermore, the coil component shown in Modification 3 can be applied to filter circuit 100 according to embodiment 1 in place of coil component 1 according to embodiment 1.

[0059] The coil component according to the third modification is configured with a ceramic layer housing 4 in which a plurality of substrates (ceramic green sheets) on which coil wiring is formed are stacked as shown in Fig. 10. In the coil component according to the third modification, the wiring patterns constituting the coils L1 and L2 are disposed inside the housing 4. As shown in Fig. 10, the wiring patterns constituting the coils L1 and L2 are formed by printing a conductive paste (Ni paste) on ceramic green sheets 4a to 4j, which are substrates, by screen printing.

[0060] As shown in Fig. 10(a), no wiring pattern is formed on the ceramic green sheet 4a. As shown in Fig. 10(b), a wiring pattern of the coil portion 3a and the lead wires 3b and 3d that constitute the coil L2 is formed on the ceramic green sheet 4b. The wiring pattern of the coil portion 3a is formed so as to make one circuit along each side of the ceramic green sheet 4b. The wiring patterns of the lead wires 3b and 3d are drawn out from the coil portion 3a to the side surface 42 of the ceramic green sheet 4b.

[0061] As shown in Fig. 10(c), a wiring pattern of a coil portion 2a and lead wires 2b and 2d that constitute the coil L1 is formed on the ceramic green sheet 4c. The wiring pattern of the coil portion 2a is formed so as to make one circuit along each side of the ceramic green sheet 4c. The wiring patterns of the lead wires 2b and 2d are drawn out from the coil portion 2a to the side surface 41 of the ceramic green sheet 4c. The wiring patterns of the lead wires 3b and 3d are formed on the side surface 42 of the ceramic green sheet 4c.

[0062] As shown in FIGS. 10(d) to (i), the ceramic green sheets 4d to 4i have wiring patterns of the lead wires 2b and 2d formed on the side surface 41 side, and wiring patterns of the lead wires 3b and 3d formed on the side surface 42 side, respectively.

[0063] 10(j), the ceramic green sheet 4j is formed with a wiring pattern of the ends 2c, 2e, 3c, and 3e that constitute the ends of the lead wires 2b, 2d, 3b, and 3d. The wiring pattern of the ends 2c and 2e is formed on the side surface 41 of the ceramic green sheet 4j, and the wiring pattern of the ends 3c and 3e is formed on the side surface 42 of the ceramic green sheet 4j. Furthermore, the ceramic green sheet 4j is formed with a wiring pattern of the connecting member 5 that connects the ends 2e and 3e.

[0064] In the coil component according to the third modification, at least one of the plurality of ceramic green sheets 4a to 4j is laminated, and a plurality of ceramic green sheets (dummy layers) without printed wiring patterns are laminated on both the top and bottom surfaces of the plurality of ceramic green sheets. The plurality of ceramic green sheets, including the dummy layers, are pressure-bonded to form an unfired housing 4 (ceramic element body). The formed housing 4 is fired, and copper electrodes are baked onto the exterior of the fired housing 4 so as to be electrically connected to the wiring patterns, thereby forming electrodes.

[0065] As described above, the coil component according to variant example 3 can be manufactured by stacking multiple substrates (ceramic green sheets) on which the coil wiring is formed, rather than by fixing the coils L1 and L2 formed from metal plates with the molded resin of the housing 4.

[0066] <Aspects> (1) A coil component according to the present disclosure comprises: a housing having a pair of first and second main surfaces opposing each other and four side surfaces connecting the first and second main surfaces; a first coil disposed inside the housing and disposed substantially parallel to the first main surface; and a second coil disposed inside the housing such that an opening of the first coil overlaps an opening when viewed from the direction of the first main surface, wherein the first coil is connected to a first lead wire and a second lead wire drawn from a first side surface of the housing; the second coil is connected to a third lead wire and a fourth lead wire drawn from a second side surface different from the first side surface; the second lead wire extends along the first side surface in the direction of the second main surface; and the fourth lead wire extends along the second side surface in the direction of the second main surface.

[0067] (2) In the coil component according to (1), the first coil and the second coil are arranged inside the housing closer to the first main surface than the second main surface.

[0068] (3) In the coil component described in (2), the first coil and the second coil are arranged closer to the first principal surface than a middle position between the first principal surface and the second principal surface.

[0069] (4) In the coil component according to any one of (1) to (3), the second lead wire and the fourth lead wire are provided to the second main surface.

[0070] (5) The coil component according to any one of (1) to (4) further includes a connection member disposed on the second main surface, the connection member electrically connecting the second lead wire and the fourth lead wire.

[0071] (6) In the coil component described in any one of (1) to (5), when the first side surface and the second side surface face each other, the side surface closer to the first lead wire is the third side surface, and the side surface closer to the second lead wire is the fourth side surface, the first lead wire and the second lead wire are drawn out from a middle portion of the first side surface that is sandwiched between the third side surface and the fourth side surface, and the third lead wire and the fourth lead wire are drawn out from a middle portion of the second side surface that is sandwiched between the third side surface and the fourth side surface.

[0072] (7) In the coil component described in (6), the second lead wire has an end on the second main surface side located in a middle portion of the first side surface sandwiched between the third side surface and the fourth side surface, and the fourth lead wire has an end on the second main surface side located in a middle portion of the second side surface sandwiched between the third side surface and the fourth side surface.

[0073] (8) In the coil component described in (6), the second lead wire has an end on the second main surface side that is located on the first side surface side of the fourth side surface, and the fourth lead wire has an end on the second main surface side that is located on the second side surface side of the fourth side surface.

[0074] (9) In the coil component described in any one of (1) to (6), when the first side surface and the second side surface face each other, and the side surface closer to the first lead wire is the third side surface and the side surface closer to the second lead wire is the fourth side surface, the first lead wire and the second lead wire are drawn out from the first side surface side of the fourth side surface, the end of the second lead wire on the second main surface side is located on the first side surface side of the fourth side surface, the third lead wire and the fourth lead wire are drawn out from the second side surface side of the fourth side surface, and the end of the fourth lead wire on the second main surface side is located on the second side surface side of the fourth side surface.

[0075] (10) In the coil component described in any one of (1) to (6), when the first side surface and the second side surface face each other, and the side surface closer to the first lead wire is the third side surface and the side surface closer to the second lead wire is the fourth side surface, the first lead wire is drawn out from the first side surface side of the fourth side surface, the second lead wire is drawn out from the first side surface side of the third side surface, and an end portion of the second main surface side is located on the first side surface side of the fourth side surface, the third lead wire is drawn out from the second side surface side of the fourth side surface, and the fourth lead wire is drawn out from the second side surface side of the third side surface, and an end portion of the second main surface side is located on the second side surface side of the fourth side surface.

[0076] (11) In the coil component according to any one of (1) to (10), the first coil and the second coil are formed from a metal plate or a metal wire.

[0077] (12) In the coil component according to any one of (1) to (11), the first coil and the second coil have rectangular openings.

[0078] (13) A filter circuit according to the present disclosure includes the coil component according to any one of (1) to (12) above, and a capacitor electrically connected to the second lead wire and the fourth lead wire of the coil component.

[0079] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0080] 1, 1A to 1G, 11 coil components, 2a, 3a coil portions, 2b, 2d, 3b, 3d lead wires, 2c, 2e, 3c, 3e end portions, 4, 4A, 4B housing, 6 wiring, 100 filter circuit, C1 capacitor.

Claims

1. A housing having a pair of first and second main surfaces facing each other and four side surfaces connecting between the first main surface and the second main surface, A first coil disposed inside the housing and disposed substantially parallel to the first main surface, A second coil disposed inside the housing such that an opening of the second coil overlaps an opening of the first coil when viewed from the direction of the first main surface, The first coil is connected to a first lead wire and a second lead wire drawn out from the first side surface side of the housing, The second coil is connected to a third lead wire and a fourth lead wire drawn out from a second side surface side different from the first side surface, The second lead wire extends in the direction of the second main surface along the first side surface side, The fourth lead wire extends in the direction of the second main surface along the second side surface side, The first coil and the second coil are coil components formed from a metal plate or a metal wire.

2. The coil component according to claim 1, wherein the first coil and the second coil are disposed inside the housing closer to the first main surface than the second main surface.

3. The coil component according to claim 2, wherein the first coil and the second coil are disposed closer to the first main surface side than an intermediate position sandwiched between the first main surface and the second main surface.

4. The coil component according to any one of claims 1 to 3, wherein the second lead wire and the fourth lead wire are provided up to the second main surface.

5. The coil component according to any one of claims 1 to 3, further comprising a connection member disposed on the second main surface and electrically connecting the second lead wire and the fourth lead wire.

6. When the first side surface and the second side surface face each other, and the side surface closer to the first lead wire is defined as the third side surface and the side surface closer to the second lead wire is defined as the fourth side surface, The first lead wire and the second lead wire are drawn out from an intermediate portion of the first side surface sandwiched between the third side surface and the fourth side surface, The coil component according to any one of claims 1 to 3, wherein the third lead wire and the fourth lead wire are drawn out from an intermediate portion of the second side surface sandwiched between the third side surface and the fourth side surface.

7. An end portion of the second lead wire on the second main surface side is at an intermediate portion of the first side surface sandwiched between the third side surface and the fourth side surface, The fourth lead-out line is at the middle part of the second side surface where the end part on the second main surface side is sandwiched between the third side surface and the fourth side surface, the coil component according to claim 6.

8. The second lead-out line has the end part on the second main surface side on the first side surface side of the fourth side surface side, The fourth lead-out line has the end part on the second main surface side on the second side surface side of the fourth side surface side, the coil component according to claim 6.

9. When the first side surface and the second side surface face each other, and the side surface closer to the first lead-out line is the third side surface and the side surface closer to the second lead-out line is the fourth side surface, The first lead-out line and the second lead-out line are led out from the first side surface side of the fourth side surface side, The second lead-out line has the end part on the second main surface side on the first side surface side of the fourth side surface side, The third lead-out line and the fourth lead-out line are led out from the second side surface side of the fourth side surface side, The fourth lead-out line has the end part on the second main surface side on the second side surface side of the fourth side surface side, the coil component according to any one of claims 1 to 3.

10. When the first side surface and the second side surface face each other, and the side surface closer to the first lead-out line is the third side surface and the side surface closer to the second lead-out line is the fourth side surface, The first lead-out line is led out from the first side surface side of the fourth side surface side, The second lead-out line is led out from the first side surface side of the third side surface side, and the end part on the second main surface side is on the first side surface side of the fourth side surface side, The third lead-out line is led out from the second side surface side of the fourth side surface side, The fourth lead-out line is led out from the second side surface side of the third side surface side, and the end part on the second main surface side is on the second side surface side of the fourth side surface side, the coil component according to any one of claims 1 to 3.

11. The first coil and the second coil have a rectangular opening, the coil component according to any one of claims 1 to 3.

12. The coil component according to any one of claims 1 to 3, A filter circuit comprising a capacitor electrically connected to the second lead-out line and the fourth lead-out line of the coil component.