Circuit board with coil component

Abstract

In a circuit substrate having a coil component, the self-resonant frequency is increased in a wide frequency band. The circuit substrate (3) has a substrate (2) and a coil component (1) mounted on the substrate (2). The coil component (1) has a drum core (10) and a winding (W) wound on a winding core portion (13) of the drum core (10). The substrate (2) has a dielectric (30) and a capacitor electrode (20) that is capacitively coupled to the winding (W) via the dielectric (30) and is given a ground potential. In this way, since a capacitance component is added between the winding (W) and the capacitor electrode (20), the capacitance component (inter-wire capacitance) between the turns of the winding (W) is apparently reduced. As a result, the self-resonant frequency can be increased in a wide frequency band.

Description

Technical Field

[0001] The present invention relates to a circuit board including a coil component, and more particularly to a circuit board including a coil component formed by winding a wire around a drum core. Background Art

[0002] As a coil component formed by winding a winding wire around a drum core, there is known a coil component described in Patent Document 1. The coil component described in Patent Document 1 has a winding wire wound around a winding core portion to form a three-layer structure, and the self-resonant frequency is adjusted by the number of turns of the winding wire in each winding layer.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-82463 Summary of the invention

[0006] However, the method described in Patent Document 1 can reduce the self-resonant frequency, but it is difficult to increase the self-resonant frequency. In addition, the method described in Patent Document 1 cannot obtain a sufficient effect in a frequency band exceeding 1 GHz.

[0007] Therefore, an object of the present invention is to increase the self-resonant frequency in a wide frequency band in a circuit board including a coil component.

[0008] A circuit substrate according to one aspect of the present invention is characterized in that it comprises: a substrate and a coil component mounted on the substrate, the coil component having a core and a winding wound on the core, the substrate having a dielectric and a capacitor electrode that is capacitively coupled to the winding via the dielectric and is given a ground potential.

[0009] According to the present invention, since a capacitance component is added between the winding and the capacitor electrode, the capacitance component (inter-wire capacitance) between the turns of the winding is reduced. Thus, the self-resonant frequency can be increased in a wide frequency band. Moreover, since a dielectric is provided between the winding and the capacitor electrode, the capacitance component between the winding and the capacitor electrode can be increased.

[0010] In the present invention, the core may also have a winding core portion wound with a winding wire, a first flange portion located at one end of the winding core portion in the axial direction, and a second flange portion located at the other end of the winding core portion in the axial direction, and the coil component also has: a first terminal electrode, which is arranged on the first flange portion and connected to one end of the winding wire; and a second terminal electrode, which is arranged on the second flange portion and connected to the other end of the winding wire, and the substrate also has a first pad pattern connected to the first terminal electrode and a second pad pattern connected to the second terminal electrode, and the height of the capacitor electrode is higher than the height of the first and second pad patterns. Thus, since the distance between the winding wire and the capacitor electrode becomes closer, a larger capacitance component can be added.

[0011] In the present invention, the capacitor electrode may also include a first capacitor electrode covering the winding from a first direction and a second capacitor electrode covering the winding from a second direction different from the first direction. Thus, the winding is covered by the capacitor electrode from multiple directions, so that a larger capacitance component can be added.

[0012] Another aspect of the present invention is a circuit substrate, characterized in that it comprises: a substrate and a coil component mounted on the substrate, the coil component having a core and a winding wound on the core, the substrate having a capacitor electrode that is capacitively coupled to the winding and is given a ground potential, the capacitor electrode comprising: a first capacitor electrode that covers the winding from a first direction; and a second capacitor electrode that covers the winding from a second direction different from the first direction.

[0013] According to the present invention, since a capacitance component is added between the winding and the capacitor electrode, the capacitance component (inter-wire capacitance) between the turns of the winding is reduced. Thus, the self-resonant frequency can be increased in a wide frequency band. Moreover, since the winding is covered by the capacitor electrode from multiple directions, a larger capacitance component can be added.

[0014] In the present invention, the capacitor electrode may be a housing member mounted on the surface of the substrate, and the coil member may be accommodated inside the housing member. Thus, a larger capacitor component can be added without performing complicated processing on the substrate.

[0015] In the present invention, the substrate may have a cavity for accommodating at least a portion of the coil component, and the capacitor electrode may be provided on the inner wall of the cavity. Thus, a larger capacitance component can be added without using other components such as a housing component.

[0016] According to the present invention, in a circuit board including a coil component, the self-resonant frequency can be increased in a wide frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic perspective view showing the appearance of the circuit board 3 according to the first embodiment of the present invention.

[0018] Figure 2 It is a schematic perspective view showing the appearance of the coil component 1 .

[0019] Figure 3 It is a schematic perspective view of the substrate 2 on which the coil component 1 is mounted.

[0020] Figure 4 It is a schematic cross-sectional view of the circuit board 3 .

[0021] Figure 5 : is an equivalent circuit diagram of the circuit board 3.

[0022] Figure 6 It is a schematic cross-sectional view for explaining the structure of a circuit board 3A according to a first modification.

[0023] Figure 7 It is a schematic perspective view showing the appearance of a circuit board 3B according to a second modification.

[0024] Figure 8 It is a schematic perspective view showing a state where the coil component 1 is removed from the circuit board 3B.

[0025] Fig. 9 It is a schematic plan view showing a state where the coil component 1 is removed from the circuit board 3B.

[0026] Fig.10 It is a schematic perspective view showing the appearance of a circuit board 3C according to a third modification.

[0027] Fig.11 1 is a schematic perspective view showing the appearance of a circuit board 3D according to a fourth modification.

[0028] Fig.12 It is a schematic perspective view showing the appearance of a circuit board 4 according to a second embodiment of the present invention.

[0029] Fig.13 It is a schematic plan view showing a state where the coil component 1 is removed from the circuit board 4 .

[0030] Fig.14 It is a schematic perspective view showing an example in which the capacitor electrodes 25 to 27 are arranged inside the cavity 2 c.

[0031] Fig.15 It is a schematic perspective view showing an example in which the capacitor electrodes 26 and 27 are arranged inside the cavity 2c.

[0032] Explanation of symbols

[0033] 1 Coil components

[0034] 2 substrate

[0035] 2a Surface of substrate

[0036] 2b Loading area

[0037] 2c Cavity

[0038] 3. 3A~3D, 4 Circuit board

[0039] 10 Drum core

[0040] 11, 12 Flange

[0041] 13. Core

[0042] 14 plate core

[0043] 20~27 Capacitor Electrode

[0044] 30 Dielectric

[0045] E1~E4 terminal electrodes

[0046] G Ground pattern

[0047] L1~L3 wiring pattern

[0048] P1, P2 land pattern

[0049] S Space

[0050] W winding. DETAILED DESCRIPTION

[0051] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0052] <First embodiment>

[0053] Figure 1 It is a schematic perspective view showing the appearance of the circuit board 3 according to the first embodiment of the present invention.

[0054] like Figure 1 As shown in FIG. 1 , the circuit board 3 of the first embodiment is composed of a substrate 2 and a coil component 1 mounted on its surface 2a. The structure of the coil component 1 is as follows: Figure 2 As shown. Figure 2 As shown, the coil component 1 includes a drum core 10, terminal electrodes E1 to E4, and a winding W. The drum core 10 includes a winding core portion 13 with the x direction as an axial direction, a flange portion 11 provided at one end of the winding core portion 13 in the x direction, and a flange portion 12 provided at the other end of the winding core portion 13 in the x direction. As the material of the drum core 10, a high magnetic permeability material such as ferrite having a magnetic permeability μ of 10 to 4000 H / m is preferably used.

[0055] The terminal electrodes E1 and E3 are provided on the flange portion 11, and the terminal electrodes E2 and E4 are provided on the flange portion 12. The terminal electrodes E1 to E4 may be formed of terminal metal parts, or may be formed of a conductive paste applied to the surface of the flange portions 11 and 12. The winding W is wound on the winding core portion 13, one end of which is connected to the terminal electrode E1, and the other end is connected to the terminal electrode E2. Although the terminal electrodes E3 and E4 may be omitted, the installation strength can be improved by using the terminal electrodes E3 and E4 as dummy terminals. In addition, the terminal electrodes E1 and E3 may be integrated, and the terminal electrodes E2 and E4 may be integrated.

[0056] Figure 3 It is a schematic perspective view of the substrate 2 on which the coil component 1 is mounted.

[0057] like Figure 3 As shown, a mounting area 2b for mounting the coil component 1 is defined on the surface 2a of the substrate 2. Pad patterns P1 and P2 are provided in the mounting area 2b. When the coil component 1 is mounted on the mounting area 2b, the terminal electrodes E1 and E3 are connected to the pad pattern P1, and the terminal electrodes E2 and E4 are connected to the pad pattern P2. Furthermore, a capacitor electrode 20 is provided in the mounting area 2b. The surface of the capacitor electrode 20 is covered by a dielectric 30. Therefore, if the coil component 1 is mounted on the mounting area 2b, as shown in the cross-sectional view Figure 4 As shown, the capacitor electrode 20 overlaps with the winding W via the dielectric 30, and the two are capacitively coupled. The pad pattern P1 and the terminal electrodes E1 and E3, and the pad pattern P2 and the terminal electrodes E2 and E4 are connected via solder 40. A space S is provided between the winding W and the dielectric 30 so that the two do not interfere with each other.

[0058] The land patterns P1 and P2 are connected to the wiring patterns L1 and L2, respectively. The wiring patterns L1 and L2 constitute a pair of input and output wirings and are connected via the winding W included in the coil component 1. On the other hand, the capacitor electrode 20 is connected to the wiring pattern L3. The wiring pattern L3 is a ground pattern to which the ground potential GND is supplied.

[0059] Figure 5 This is an equivalent circuit diagram of the circuit board 3 according to the present embodiment.

[0060] like Figure 5As shown, the circuit substrate 3 of the present embodiment is connected with a winding W that functions as a coil between the wiring pattern L1 and the wiring pattern L2, and a capacitance component is added between the winding W and the capacitor electrode 20. The amount of the added capacitance component can be adjusted according to the area of ​​the capacitor electrode 20, the thickness and dielectric constant of the dielectric 30, the size of the space S, etc. If such a capacitance component is added, the capacitance component (inter-wire capacitance) generated between adjacent turns of the winding W has a smaller effect on the self-resonant frequency, and as a result, the self-resonant frequency becomes higher. This means that the inter-wire capacitance is reduced in appearance. Such an effect can also be obtained in a frequency band exceeding 1GHz.

[0061] In this way, the circuit substrate 3 of the present embodiment is provided with the capacitor electrode 20 of the ground potential GND and is arranged in the mounting area 2b of the substrate 2. Therefore, if the coil component 1 is mounted on the substrate 2, a capacitance component is added between the winding W and the capacitor electrode 20. Thus, it is possible to obtain a self-resonant frequency higher than the self-resonant frequency calculated according to the actual line-to-line capacitance without designing the coil component 1. Moreover, since the capacitor electrode 20 is covered by the dielectric 30, a larger capacitance component can be added, and a short circuit defect between the winding W and the capacitor electrode 20 can be prevented.

[0062] Figure 6 It is a schematic cross-sectional view for explaining the structure of a circuit board 3A according to a first modification.

[0063] Figure 6 The circuit substrate 3A of the first modified example shown is different from the circuit substrate 3 of the first embodiment in that the height T2 of the capacitor electrode 20 based on the surface 2a of the substrate 2 is higher than the height T1 of the pad patterns P1 and P2 based on the surface 2a of the substrate 2. The back surface of the substrate 2 is covered with a ground pattern G, and the capacitor electrode 20 is composed of a pillar conductor that penetrates the substrate 2 and is connected to the ground pattern G. The other basic structures are the same as those of the circuit substrate 3 of the first embodiment, so the same symbols are attached to the same elements, and repeated descriptions are omitted.

[0064] In the first variant, the height T2 of the capacitor electrode 20 is higher than the height T1 of the pad patterns P1 and P2, so the capacitor electrode 20 can be closer to the winding W. That is, the space S can be reduced. Thus, a larger capacitance component can be added. However, if the height T2 of the capacitor electrode 20 is too large, the distance between the winding W and the capacitor electrode 20 becomes too close, and depending on the frequency band used, the two may cause a high-frequency short circuit. Therefore, considering the frequency band used, the distance between the winding W and the capacitor electrode 20 is preferably designed to ensure that no high-frequency short circuit occurs.

[0065] Figure 7 2 is a schematic perspective view showing the appearance of a circuit board 3B according to a second modification. Figure 8 and Fig. 9 These are a schematic perspective view and a schematic plan view respectively showing a state where the coil component 1 is removed from the circuit board 3B.

[0066] Figure 7 to Figure 9 The circuit board 3B of the second modification shown is different from the circuit board 3 of the first embodiment in that the capacitor electrode 20 is composed of three capacitor electrodes 21 to 23. The other basic structures are the same as the circuit board 3 of the first embodiment, so the same elements are marked with the same symbols and repeated descriptions are omitted.

[0067] The capacitor electrode 21 constitutes the xy plane, and when the coil component 1 is mounted, it overlaps with the winding W in the z direction. In contrast, the capacitor electrodes 22 and 23 constitute the xz plane, and when the coil component 1 is mounted, they overlap with the winding W in the y direction. Thus, the winding W overlaps with the capacitor electrode 20 from three directions, so a larger capacitance component can be added. In particular, when the planar size of the coil component 1 is small, it is difficult to add a sufficient capacitance component only by the capacitor electrode 21 constituting the xy plane, but according to this example, even when the planar size of the coil component 1 is small, a sufficient capacitance component can be added.

[0068] Fig.10 It is a schematic perspective view showing the appearance of a circuit board 3C according to a third modification.

[0069] Fig.10 The circuit substrate 3C of the third variation shown is different from the circuit substrate 3 of the first embodiment in that the capacitor electrode 24 is composed of a shell component. The other basic structures are the same as the circuit substrate 3 of the first embodiment, so the same elements are marked with the same symbols and repeated descriptions are omitted. The capacitor electrode 24 is a metal shell component mounted on the surface 2a of the substrate 2, and the coil component 1 is stored therein. The capacitor electrode 24 is given a ground potential GND. In this way, even when a metal shell component is used as the capacitor electrode 24, the capacitor electrode 24 and the winding W are capacitively coupled, so the self-resonant frequency can be adjusted.

[0070] However, since the capacitor electrode 24 is in a shell shape, if it is connected to the ground pattern at multiple locations, the ground pattern including the capacitor electrode 24 becomes annular. In this case, the capacitor electrode 24 and the ground pattern function as a coil, so the inductance is greatly reduced. In order to prevent this, it is preferred that the connection position of the capacitor electrode 24 and the ground pattern is one location. In addition, when the capacitor electrode 24 itself is annular, it is preferably designed that the capacitor electrode 24 itself does not become annular by arranging an opening at a part of the capacitor electrode 24, or by forming a part of the capacitor electrode 24 with a non-conductive material.

[0071] Fig.11 It is a schematic perspective view showing the appearance of a circuit board 3D according to a fourth modification.

[0072] Fig.11 The circuit board 3D of the fourth variation shown is different from the circuit board 3 of the first embodiment in that a planar core 14 is added to the coil component 1. The other basic structures are the same as the circuit board 3 of the first embodiment, so the same elements are marked with the same symbols and repeated descriptions are omitted.

[0073] The plate-like core 14 is fixed to the flanges 11 and 12, and functions as a magnetic circuit connecting the flanges 11 and 12. As the material of the plate-like core 14, it is preferable to use a high magnetic permeability material similar to the drum core 10. In this way, if the plate-like core 14 is added, a closed magnetic circuit is formed by the drum core 10 and the plate-like core 14, so that the inductance can be increased.

[0074] <Second embodiment>

[0075] Fig.12 2 is a schematic perspective view showing the appearance of a circuit board 4 according to a second embodiment of the present invention. Fig.13 It is a schematic plan view showing a state where the coil component 1 is removed from the circuit board 4 .

[0076] like Fig.12 and Fig.13 As shown, the circuit substrate 4 of the second embodiment is different from the circuit substrate 3 of the first embodiment in that a cavity 2c is provided on the substrate 2, and a coil component 1 is accommodated inside the cavity 2c. Pad patterns P1 and P2 are provided on the bottom surface of the cavity 2c, and capacitor electrodes 25 and 26 are provided on the inner wall (xz plane) of the cavity 2c. The other basic structures are the same as the circuit substrate 3 of the first embodiment, so the same elements are marked with the same symbols, and repeated descriptions are omitted.

[0077] In the present embodiment, if the coil component 1 is mounted inside the cavity 2c, the capacitor electrodes 25 and 26 are capacitively coupled with the winding W. Thus, the self-resonant frequency can be adjusted in the same manner as in the first embodiment. Moreover, since the capacitor electrodes 25 and 26 are arranged on the inner wall of the cavity 2c, a larger capacitance component can be added compared to the first embodiment, and there is no need to use a supporting member for supporting the capacitor electrodes 25 and 26. In addition, since the coil component 1 is accommodated in the cavity 2c, the circuit substrate 4 can be made thinner. However, the entirety of the coil component 1 does not need to be accommodated in the cavity 2c, and only a portion of the coil component 1 can be accommodated in the cavity 2c.

[0078] In addition, Fig.13In the substrate 2 shown in FIG. 1 , the capacitor electrodes 25 and 26 are also formed on the surface 2a of the substrate 2, but this is not essential. Fig.13 In the substrate 2 shown in FIG. 1 , capacitor electrodes 25 and 26 are provided on the inner wall of the cavity 2c constituting the xz plane, but there is no particular limitation on the position of the capacitor electrodes. Fig.14 As shown in the example, in addition to the capacitor electrodes 25 and 26, a capacitor electrode 27 may be provided on the bottom surface of the cavity 2c, or Fig.15 As in the example shown in the figure, instead of deleting the capacitor electrode 25, a capacitor electrode 27 is provided on the bottom surface of the cavity 2c. In this way, the self-resonant frequency can be adjusted by the position and area where the capacitor electrode is formed.

[0079] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention, and these modifications are naturally included in the scope of the present invention.

Claims

1. A circuit substrate, characterized in that: have: substrate; and a coil component mounted on the substrate, The coil component includes a core and a winding wire wound around the core. The core has: a winding core portion around which the winding wire is wound; a first flange portion located at one end of the winding core portion in the axial direction; and a second flange portion located at the other end of the winding core portion in the axial direction. The coil component further includes: a first terminal electrode provided on the first flange portion and connected to one end of the winding wire; and a second terminal electrode provided on the second flange portion and connected to the other end of the winding wire. The substrate comprises a first pad pattern connected to the first terminal electrode, a second pad pattern connected to the second terminal electrode, a dielectric arranged so as to form a space between the dielectric and the winding, and a capacitor electrode located between the first pad pattern and the second pad pattern and capacitively coupled to the winding via the dielectric and the space and given a ground potential, The first pad pattern, the second pad pattern, and the capacitor electrode are all formed on a surface of the substrate opposite to the coil component, and are in the shape of a flat plate parallel to the surface of the substrate. The capacitor electrode has a height higher than that of the first pad pattern and the second pad pattern.

2. A circuit substrate, characterized in that: have: substrate; and a coil component mounted on the substrate, The coil component includes a core and a winding wire wound around the core. The substrate has a capacitance electrode which is capacitively coupled to the winding and is given a ground potential. The capacitor electrode includes: a first flat capacitor electrode, which is fixed to the substrate without contacting the coil component and covers the winding from a first direction; and a second flat capacitor electrode, which is fixed to the substrate without contacting the coil component and covers the winding from a second direction different from the first direction.

3. The circuit substrate according to claim 2, characterized in that: The capacitor electrode is a shell component mounted on the surface of the substrate. The coil component is accommodated in the housing component.

4. The circuit substrate according to claim 2, characterized in that: The substrate has a cavity for accommodating at least a portion of the coil component. The capacitor electrode is arranged on the inner wall of the cavity.

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