The present invention relates to a coil component and, more particularly, to a coil component having a structure in which a helical coil pattern is embedded in a resin body.
As a coil component having a structure in which a helical coil pattern is embedded in a resin body, a coil component described in JP 2006-324489A is known.
However, in the coil component described in JP 2006-324489A, it is difficult to sufficiently increase a self-resonance frequency (SRF).
It is therefore an object of the present invention to increase a self-resonance frequency in a coli component having a structure in which a helical coil pattern is embedded in a resin body.
A coil component according to the present invention includes: a resin body having a first resin-based insulating material and a second resin-based insulating material lower in relative permittivity than the first resin-based insulating material; a coil pattern embedded in the resin body and helically wound in a plurality of turns; and first and second terminal electrodes formed on the surface of the resin body and connected respectively to one and the other ends of the coil pattern. The coil pattern has a part covered with the first resin-based insulating material and another part covered with the second resin-based insulating material.
According to the present invention, sufficient mechanical strength can be ensured by the first resin-based insulating material, and floating capacitance can be reduced by the second resin-based insulating material low in relative permittivity. This can increase a self-resonance frequency.
In the present invention, the second resin-based insulating material may be provided between the first and second terminal electrodes and the coil pattern. This can reduce the floating capacitance between the first and second terminal electrodes and the coil pattern.
In the present invention, the second resin-based insulating material may be provided between adjacent turns of the coil pattern. This can reduce the floating capacitance generated between adjacent turns of the coil pattern.
In the present invention, the resin body may include a first resin layer, a second resin layer, and a third resin layer provided between the first and second resin layers, the coil pattern may include a plurality of first horizontal sections provided on the first resin layer and embedded in the third resin layer, a plurality of second horizontal sections provided on the third resin layer and embedded in the second resin layer, a plurality of first vertical sections penetrating the third resin layer and connecting each of one ends of the plurality of first horizontal sections to each of one ends of the plurality of second horizontal sections, and a plurality of second vertical sections penetrating the third resin layer and connecting each of the other ends of the plurality of first horizontal sections to each of other ends of the plurality of second horizontal sections. With this configuration, the coil axis of the coil pattern can be made perpendicular to the stacking direction of the resin layers.
In this case, the first and second terminal electrodes are provided on the second resin layer, wherein the second resin layer may be made of the second resin-based insulating material, and wherein a part of the third resin layer that embeds the first horizontal section therein may be made of the second resin-based insulating material, while the remaining part thereof may be made of the first resin-based insulating material. In the former case, the floating capacitance generated between the first and second terminal electrodes and the second horizontal sections of the coil pattern and the floating capacitance generated between adjacent second horizontal sections can be reduced. In the latter case, the floating capacitance between adjacent first horizontal sections can be reduced.
In the present invention, the first and second terminal electrodes may be arranged in the axial direction of the coil pattern. This reduces a potential difference between the first and second terminal electrodes and the coil pattern, thereby further reducing floating capacitance.
In this case, the first and second terminal electrodes may be formed on the surface of the resin body parallel to the axial direction without being formed on the surface thereof perpendicular to the axial direction. This makes magnetic flux less likely to interface with the first and second terminal electrodes, thereby suppressing the occurrence of an eddy current.
In the present invention, the first resin-based insulating material may be added with filer, while the second resin-based insulating material is added with no filler. This can further enhance the strength of the first resin-based insulating material and further reduce the relative permittivity of the second resin-based insulating material.
According to the present invention, it is possible to increase the self-resonance frequency in a coli component having a structure in which a helical coil pattern is embedded in a resin body.
The above features and advantages of the present disclosure will be more apparent from the following description of certain preferred embodiments taken in conjunction with the accompanying drawings, in which:
Preferred embodiments of the present disclosure will be explained below in detail with reference to the accompanying drawings.
The coil component 1 according to the first embodiment is a surface-mountable chip-type electronic component and includes, as illustrated in
The resin body 10 has a structure in which four resin layers 11 to 14 are stacked in this order in the z-direction. The resin layers 11 and 13 are made of a resin-based insulating material obtained by adding filler such as silica to an epoxy- or acrylic-based resin material. The resin-based insulating material constituting the resin layer 11 and that constituting the resin layer 13 may be the same or different. The resin layers 12 and 14 are made of a resin material including no filler, such as bismaleimide or liquid crystal polymer. The resin-based insulating material constituting the resin layer 12 and that constituting the resin layer 14 may be the same or different.
Thus, the resin-based insulating material constituting the resin layers 11 and 13 is higher in strength and processability than that constituting the resin layers 12 and 14. On the other hand, the resin-based insulating material constituting the resin layers 12 and is made of a resin material having a low relative permittivity and is added with no filler such as silica and is thus lower in relative permittivity than the resin-based insulating material constituting the resin layers 11 and 13. For example, the resin-based insulating material constituting the resin layers 11 and 13 has a relative permittivity E of about 3.3 at 1 GHz, and the resin-based insulating material constituting the resin layers 12 and 14 has a relative permittivity E of about 2.4 at 1 GHz.
As illustrated in
With the above configuration, the coil pattern C helically wound in a plurality of turns can be obtained. The coil pattern C has a coil axis extending in the x-direction. The other end of the second horizontal section constitutes one end of the coil pattern C and is connected to the terminal electrode E1 through a via conductor 71 penetrating the resin layer 14. One end of the second horizontal section 45 constitutes the other end of the coil pattern C and is connected to the terminal electrode E2 through a via conductor 72 penetrating the resin layer 14. The terminal electrodes E1 and E2 are each a bottom-surface terminal formed only on the xy surface of the resin body 10. That is, the terminal electrodes E1 and E2 do not cover the yz surface of the resin body 10, so that when the coil component 1 is mounted on a circuit board using a solder, the yz surface of the resin body 10 is not covered with solder fillets. This improves a mounting density. Further, magnetic flux generated from the coil pattern C is made less likely to interfere with the terminal electrodes E1, E2 and solder, making it possible to suppress the occurrence of an eddy current.
As illustrated in
Further, in the present embodiment, the terminal electrode E1 also overlaps a part of the second horizontal section 42, and the terminal electrode E2 also overlaps a part of the second horizontal section 44. Thus, floating capacitance is also generated between the terminal electrode E1 and the second horizontal section 42 and between the terminal electrode E2 and the second horizontal section 44. The second horizontal section 42 has a longer wiring distance from the terminal electrode E1 than the second horizontal section 41, so that the floating capacitance of the terminal electrode E1 and second horizontal section 42 per unit area is larger than the floating capacitance of the terminal electrode E1 and second horizontal section 41 per unit area due to influence of a voltage drop. Similarly, the second horizontal section 44 has a longer wiring distance from the terminal electrode E2 than the second horizontal section 45, so that the floating capacitance of the terminal electrode E2 and second horizontal section 44 per unit area is larger than the floating capacitance of the terminal electrode E2 and second horizontal section 45 per unit area due to influence of a voltage drop. When the terminal electrodes E1 and E2 each thus overlap some of the second horizontal sections 41 to 45, the effect of the use of a resin-based insulating material having a low relative permittivity as the material of the resin layer 14 becomes larger.
Further, in the present embodiment, the first horizontal sections 31 to 34 are embedded in the resin layer 12, and the resin layer 12 is made of a resin-based insulating material having a low relative permittivity, so that the floating capacitance between the first horizontal sections 31 to 34 adjacent to one another in the x-direction, that is, the floating capacitance generated between adjacent turns of the coil pattern C can be reduced.
The first vertical sections 51 to 54 and second vertical sections 61 to 64 mostly penetrate the resin layer 13 having high strength, making it possible to ensure sufficient mechanical strength of the entire resin body 10. To ensure mechanical strength of the resin body 10, a thickness T13 of the resin layer 13 is preferably three or more times the thicknesses T12 and T14 of the resin layers 12 and 14. For example, by setting the T12, T13, and T14 to about 20 μm, about 115 μm, and about 30 μm, respectively, it is possible to reduce floating capacitance while ensuring mechanical strength of the resin body 10.
As described above, in the coil component 1 according to the present embodiment, the coil pattern C is embedded in the resin body 10 and is covered with the resin layers 11 and 13 made of a resin-based insulating material having high strength and the resin layers 12 and 14 made of a resin-based insulating material having a low relative permittivity, so that it is possible to prevent a reduction in a self-resonance frequency due to floating capacitance while ensuring mechanical strength of the resin body 10.
Further, in the present embodiment, the terminal electrodes E1 and E2 are arranged in the axial direction (x-direction) of the coil pattern C, so that the terminal electrode E1 does not overlap the second horizontal sections (e.g., second horizontal sections 44 and 45) having a comparatively longer wiring distance therefrom and, similarly, the terminal electrode E2 does not overlap the second horizontal sections (e.g., second horizontal sections 41 and 42) having a comparatively longer wiring distance therefrom. This reduces the difference between a potential between the terminal electrodes E1 and the second horizontal sections 41 and 42 overlapping the terminal electrode E1 and a potential between the terminal electrodes E2 and the second horizontal sections 44 and 45 overlapping the terminal electrode E2, so that it is possible to further reduce floating capacitance as compared with a case where the terminal electrodes E1 and E2 are arranged in the y-direction.
The following describes a manufacturing method for the coil component 1 according to the present embodiment.
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As described above, in the manufacturing method for the coil component 1 according to the present embodiment, the first horizontal sections 31 to 34 and second horizontal sections 41 to 45 are formed respectively on the resin layers 11 and 13 high in strength and processability, and the first vertical sections 51 to 54 and second vertical sections 61 to 64 mostly penetrate the resin layer 13 high in strength and processability. Thus, higher processing accuracy can be ensured as compared with a case where the entire resin body 10 is constituted by a resin-based insulating material having a low relative permittivity.
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As the material of the resin layer 14 positioned between the terminal electrodes E1, E2 and a first pattern of the coil pattern C starting from the terminal electrode E2, a resin-based insulating material having a low relative permittivity is used. The coil pattern C is mostly embedded in the resin layer 13 having high strength. Further, the resin layer 12 positioned between predetermined adjacent turns of the coil pattern C is also made of a resin-based insulating material having a relative permittivity lower than that of the resin layer 13. This makes it possible to reduce the floating capacitance generated between the terminal electrodes E1, E2 and the first turn of the coil pattern C and the floating capacitance generated between predetermined adjacent turns of the coil pattern C.
As exemplified by the coil component 4 according to the fourth embodiment, the coil pattern C may have a coil axis extending in the stacking direction (z-direction) in the present invention.
As illustrated in
It is apparent that the present disclosure is not limited to the above embodiments, but may be modified and changed without departing from the scope and spirit of the disclosure.
For example, in the above embodiments, the resin-based insulating material constituting the resin layers 11 and 13 is added with filler, while the resin-based insulating material constituting the resin layers 12 and 14 is added with no filler; however, this is not essential in the present invention. Further, the same resin material may be used for the resin layers 11, 13 and resin layers 12, 14 with filter added to the resin layers 11, 13 so as to enhance strength and with no filer added to the resin layers 12, 14 so as not to increase the relative permittivity.
Number | Date | Country | Kind |
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2020-177158 | Oct 2020 | JP | national |