Patent Application
20210249184
The present invention relates to a coil component.
The coil component that is described in Patent Literature 1 (Japanese Unexamined Patent Publication No. 2014-154716) is known as an example of coil components. The coil component described in Patent Literature 1 includes an element body including a pair of end surfaces facing each other, a pair of main surfaces facing each other, and a pair of side surfaces facing each other, a coil disposed in the element body, having a coil axis extending along the facing direction of the pair of side surfaces, and configured to include a plurality of turns, and a pair of external electrodes to which the coil is connected. In the coil, an end portion of the turn closest to one of the side surfaces in the facing direction of the pair of side surfaces is connected to one of the external electrodes and an end portion of the turn closest to the other side surface is connected to the other external electrode.
In the coil component, the turn of the coil connected to one external electrode (the other external electrode) has a large potential difference at the part facing the other external electrode (one external electrode). Accordingly, electric field concentration occurs at the part of the turn facing the other external electrode (one external electrode). As a result, in the coil component, the parasitic capacitance (stray capacitance) generated between the turn of the coil and the external electrode increases, and thus the self-resonant frequency (SRF) decreases and the quality factor (Q) value also decreases in coil characteristics.
An object of one aspect of the present invention is to provide a coil component with which it is possible to improve the Q value while increasing the self-resonant frequency.
A coil component according to one aspect of the present invention includes an element body including a pair of end surfaces facing each other, a pair of main surfaces facing each other, and a pair of side surfaces facing each other, a coil disposed in the element body, having a coil axis extending along a facing direction of the pair of side surfaces, and including a plurality of turns, and a first external electrode to which one end of the coil is connected and a second external electrode to which the other end of the coil is connected. Each of the first external electrode and the second external electrode is disposed on at least one of the main surfaces and the first external electrode and the second external electrode are separated from each other in a facing direction of the pair of end surfaces, an end portion of a first outermost turn as the turn closest to one of the side surfaces in the facing direction of the pair of side surfaces is connected to the first external electrode and an end portion of a second outermost turn as the turn closest to the other side surface in the facing direction of the pair of side surfaces is connected to the second external electrode in the coil, and an area at which the first outermost turn faces the second external electrode and an area at which the second outermost turn faces the first external electrode are smaller than an area at which the turns other than the first outermost turn and the second outermost turn face the first external electrode or the second external electrode.
In the coil component according to one aspect of the present invention, the area at which the first outermost turn faces the second external electrode and the area at which the second outermost turn faces the first external electrode are smaller than the area at which the turns other than the first outermost turn and the second outermost turn face the first external electrode or the second external electrode. As a result, in the coil component, it is possible to reduce the parasitic capacitance that is generated between the first outermost turn and the second external electrode and between the second outermost turn and the first external electrode. As a result, in the coil component, it is possible to improve the Q value while increasing the self-resonant frequency.
In one embodiment, each of the first external electrode and the second external electrode may be disposed only on one of the main surfaces. In this configuration, the parasitic capacitance that is formed between the first outermost turn and the second external electrode and between the second outermost turn and the first external electrode can be reduced. Accordingly, in the coil component, it is possible to improve the Q value while increasing the self-resonant frequency.
In one embodiment, the first external electrode may include a first electrode part disposed on one of the end surfaces and a second electrode part disposed on one of the main surfaces and be disposed so as to straddle one of the end surfaces and one of the main surfaces, the second external electrode may include a third electrode part disposed on the other end surface and a fourth electrode part disposed on one of the main surfaces and be disposed so as to straddle the other end surface and one of the main surfaces, and an area at which the first outermost turn faces the first electrode part and an area at which the second outermost turn faces the third electrode part may be smaller than an area at which the turns other than the first outermost turn and the second outermost turn face the first electrode part or the third electrode part. In a case where the coil component is solder-fixed to a circuit board or the like in this configuration, solder is also formed at the first electrode part and the third electrode part positioned on the end surfaces of the element body, and thus the coil component can be firmly fixed to the circuit board or the like. In the coil component having this configuration, the stray capacitance that is formed between the first outermost turn and the first electrode part and between the second outermost turn and the third electrode part can be reduced. Accordingly, in the coil component, it is possible to improve the characteristics (self-resonant frequency and Q value) while ensuring mountability in relation to a circuit board or the like.
According to one aspect of the present invention, it is possible to improve the Q value while increasing the self-resonant frequency.
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals with redundant description omitted.
As illustrated in
The element body 2 has a pair of end surfaces 2a and 2b facing each other, a pair of main surfaces 2c and 2d facing each other, and a pair of side surfaces 2e and 2f facing each other. The facing direction of the pair of main surfaces 2c and 2d, that is, the direction parallel to the end surfaces 2a and 2b is a first direction D1. The facing direction of the pair of side surfaces 2e and 2f is a second direction D2. The facing direction of the pair of end surfaces 2a and 2b, that is, the direction parallel to the main surfaces 2c and 2d is a third direction D3. In the present embodiment, the first direction D1 is the height direction of the element body 2. The second direction D2 is the width direction of the element body 2 and is orthogonal to the first direction D1. The third direction D3 is the longitudinal direction of the element body 2 and is orthogonal to the first direction D1 and the second direction D2.
The pair of end surfaces 2a and 2b extend in the first direction D1 so as to interconnect the pair of main surfaces 2c and 2d. The pair of end surfaces 2a and 2b also extend in the second direction D2, that is, the short side direction of the pair of main surfaces 2c and 2d. The pair of side surfaces 2e and 2f extend in the first direction D1 so as to interconnect the pair of main surfaces 2c and 2d. The pair of side surfaces 2e and 2f also extend in the third direction D3, that is, the long side direction of the pair of end surfaces 2a and 2b. The multilayer coil component 1 is, for example, solder-mounted on an electronic device (such as a circuit board and an electronic component). In the multilayer coil component 1, the main surface (one main surface) 2d constitutes a mounting surface facing the electronic device.
The element body 2 is configured by stacking a plurality of dielectric layers in the second direction D2. The element body 2 has the plurality of stacked dielectric layers. In the element body 2, the direction in which the plurality of dielectric layers are stacked coincides with the second direction D2. In the actual element body 2, each dielectric layer is integrated to the extent that the boundary between the dielectric layers cannot be visually recognized. Each dielectric layer is formed of a dielectric material containing a glass component. In other words, the element body 2 contains a dielectric material containing a glass component as a compound of elements constituting the element body 2. The glass component is, for example, borosilicate glass. The dielectric material is, for example, dielectric ceramic such as BaTiO3-based dielectric ceramic, Ba(Ti,Zr)O3-based dielectric ceramic, and (Ba,Ca)TiO3-based dielectric ceramic. Each dielectric layer is made of a sintered body of a ceramic green sheet containing a glass ceramic material. It should be noted that each dielectric layer may be made of a magnetic material. The magnetic material includes, for example, a Ni—Cu—Zn-based ferrite material, a Ni—Cu—Zn—Mg-based ferrite material, or a Ni—Cu-based ferrite material. The magnetic material constituting each dielectric layer may contain an Fe alloy. Each dielectric layer may be made of a nonmagnetic material. The nonmagnetic material includes, for example, a glass ceramic material or a dielectric material.
As illustrated in
The first external electrode 3 and the second external electrode 4 are disposed so as to be misaligned with each other in the second direction D2 when viewed from the first direction D1. Specifically, the first external electrode 3 is disposed close to the side surface 2e when viewed from the second direction D2 and the second external electrode 4 is disposed close to the side surface 2f when viewed from the second direction D2. In the present embodiment, the surface of the first external electrode 3 is substantially flush with the main surface 2d. The surface of the second external electrode 4 is substantially flush with the main surface 2d.
The first external electrode 3 and the second external electrode 4 contain a conductive material. The conductive material contains, for example, Ag or Pd. The first external electrode 3 and the second external electrode 4 are configured as a sintered body of conductive paste containing conductive material powder. The conductive material powder includes, for example, Ag powder or Pd powder. A plating layer may be formed on the surfaces of the first external electrode 3 and the second external electrode 4. The plating layer is formed by, for example, electroplating or electroless plating. The plating layer contains, for example, Ni, Sn, or Au.
Each of the first external electrode 3 and the second external electrode 4 is configured by stacking a plurality of electrode layers (not illustrated). The electrode layer has a rectangular shape when viewed from the second direction D2. Each electrode layer is provided in a defect portion formed in the corresponding dielectric layer. The electrode layer is formed by firing conductive paste positioned in a defect portion formed on a green sheet. The green sheet and the conductive paste are fired at the same time. Accordingly, the electrode layer is obtained from the conductive paste when the dielectric layer is obtained from the green sheet. In the actual first external electrode, each electrode layer is integrated to the extent that the boundary between the electrode layers cannot be visually recognized.
The multilayer coil component 1 includes a coil 5 disposed in the element body 2 as illustrated in
In the coil 5, the turn 6, the turn 7, the turn 8, the turn 9, the turn 10, and the turn 11 are disposed in this order between the side surface 2e and the side surface 2f. The turn 7, the turn 8, the turn 9, and the turn 10 are disposed between the turn 6 and the turn 11. The turn 6, the turn 7, the turn 8, the turn 9, the turn 10, and the turn 11 have a constant width. In other words, the turn 6, the turn 7, the turn 8, the turn 9, the turn 10, and the turn 11 are formed to have the same width.
The turn 6 is the first outermost turn that is closest to the side surface 2e (one side surface) in the second direction D2. An end portion 6a of the turn 6 is connected to the first external electrode 3. As a result, the coil 5 is connected to the first external electrode 3. The turn 7 is connected to the turn 6. The turn 8 is connected to the turn 7. The turn 9 is connected to the turn 8. The turn 10 is connected to the turn 9. The turn 11 is the second outermost turn that is closest to the side surface 2f (the other side surface) in the second direction D2. An end portion 11a of the turn 11 is connected to the second external electrode 4. As a result, the coil 5 is connected to the second external electrode 4.
In the multilayer coil component 1, the area at which the turn 6 faces the second external electrode 4 and the area at which the turn 11 faces the first external electrode 3 are smaller than the area at which the turns 7, 8, 9, and 10 other than the turn 6 and the turn 11 face the first external electrode 3 or the second external electrode 4. As illustrated in
The first external electrode 3 is not disposed at a position facing the turn 11. In other words, the turn 11 does not face the first external electrode 3. The facing area between the turn 11 and the first external electrode 3 is “0”. The turns 7, 8, 9, and 10 face the first external electrode 3 (diagonal parts in
The plurality of turns 6, 7, 8, 9, 10, and 11 contain a conductive material. The conductive material contains Ag or Pd. The plurality of turns 6, 7, 8, 9, 10, and 11 are configured as a sintered body of conductive paste containing conductive material powder. The conductive material powder includes, for example, Ag powder or Pd powder. In the present embodiment, the plurality of turns 6, 7, 8, 9, 10, and 11 contain the same conductive material as the first external electrode 3 and the second external electrode 4. The plurality of turns 6, 7, 8, 9, 10, and 11 may contain a conductive material different from the conductive material of the first external electrode 3 and the second external electrode 4.
The plurality of turns 6, 7, 8, 9, 10, and 11 are provided in defect portions formed in the corresponding dielectric layers. The plurality of turns 6, 7, 8, 9, 10, and 11 are formed by firing conductive paste positioned in a defect portion formed on a green sheet. As described above, the green sheet and the conductive paste are fired at the same time. Accordingly, the plurality of turns 6, 7, 8, 9, 10, and 11 are obtained from the conductive paste when the dielectric layers are obtained from the green sheet.
The defect portion formed on the green sheet is formed by, for example, the following process. First, the green sheet is formed by applying element body paste containing a constituent material of a dielectric layer and a photosensitive material onto a base material. The base material is, for example, a PET film. The photosensitive material contained in the element body paste may be either a negative-type photosensitive material or a positive-type photosensitive material and known photosensitive materials can be used. Next, the green sheet is exposed and developed by a photolithography method and by means of a mask corresponding to the defect portion, and then the defect portion is formed on the green sheet on the base material. The green sheet on which the defect portion is formed is an element body pattern.
The plurality of turns 6, 7, 8, 9, 10, and 11 are formed by, for example, the following process. First, a conductor material layer is formed by applying conductive paste containing a photosensitive material onto a base material. The photosensitive material contained in the conductive paste may be either a negative-type photosensitive material or a positive-type photosensitive material and known photosensitive materials can be used. Next, the conductor material layer is exposed and developed by a photolithography method and by means of a mask corresponding to the defect portion, and then a conductor pattern corresponding to the shape of the defect portion is formed on the base material.
The multilayer coil component 1 is obtained by, for example, the following process following the process described above. A sheet in which the element body pattern and the conductor pattern are in the same layer is prepared by combining the conductor pattern with the defect portion of the element body pattern. A predetermined number of the sheets are prepared, a stacked body is obtained by stacking the sheets, and the stacked body is heat-treated. Then, a plurality of green chips are obtained from the stacked body. In this process, the green stacked body is cut into chips by means of, for example, a cutting machine. As a result, the plurality of green chips having a predetermined size can be obtained. Next, the green chips are fired. The multilayer coil component 1 is obtained as a result of the firing. In the multilayer coil component 1, the first external electrode 3, the second external electrode 4, and the coil 5 are integrally formed.
As described above, in the multilayer coil component 1 according to the present embodiment, the area at which the turn 6 faces the second external electrode 4 and the area at which the turn 11 faces the first external electrode 3 are smaller than the area at which the turns 7, 8, 9, and 10 other than the turn 6 and the turn 11 face the first external electrode 3 or the second external electrode 4. In the multilayer coil component 1 according to the present embodiment, the turn 6 and the second external electrode 4 and the turn 11 and the first external electrode 3 are not disposed so as to face each other. As a result, in the multilayer coil component 1, it is possible to reduce the parasitic capacitance that is generated (prevent parasitic capacitance from being generated) between the turn 6 and the second external electrode 4 and between the turn 11 and the first external electrode 3. As a result, in the multilayer coil component 1, it is possible to improve the Q value while increasing the self-resonant frequency.
In a multilayer coil component 100 illustrated in
In
In the multilayer coil component 1 according to the present embodiment, each of the first external electrode 3 and the second external electrode 4 is disposed only on the main surface 2d of the element body 2. In this configuration, the parasitic capacitance that is formed between the turn 6 and the second external electrode 4 and between the turn 11 and the first external electrode 3 can be reduced. Accordingly, in the multilayer coil component 1, it is possible to improve the Q value while increasing the self-resonant frequency.
A second embodiment will be described below. As illustrated in
The first external electrode 20 is disposed on the end surface 2a side of the element body 2. The second external electrode 30 is disposed on the end surface 2b side of the element body 2. The first external electrode 20 and the second external electrode 30 are separated from each other in the third direction D3.
The first external electrode 20 is disposed over the end surface 2a and the main surface 2d. The first external electrode 20 has an L shape when viewed from the second direction D2. The first external electrode 20 has a plurality of electrode parts 20a and 20b. In the present embodiment, the first external electrode 20 has a pair of electrode parts 20a and 20b. The electrode part (first electrode part) 20a and the electrode part (second electrode part) 20b are connected in the ridgeline portion of the element body 2 and are electrically connected to each other. In the present embodiment, the electrode part 20a and the electrode part 20b are integrally formed. The electrode part 20a extends along the first direction D1. The electrode part 20a has a rectangular shape when viewed from the third direction D3. The electrode part 20b extends along the third direction D3. The electrode part 20b has a rectangular shape when viewed from the first direction D1. The electrode parts 20a and 20b extend along the second direction D2. The surface of the first external electrode 20 is substantially flush with each of the end surface 2a and the main surface 2d.
The second external electrode 30 is disposed over the end surface 2b and the main surface 2d. The second external electrode 30 has an L shape when viewed from the second direction D2. The second external electrode 4 has a plurality of electrode parts 30a and 30b. In the present embodiment, the second external electrode 30 has a pair of electrode parts 30a and 30b. The electrode part (third electrode part) 30a and the electrode part (fourth electrode part) 30b are connected in the ridgeline portion of the element body 2 and are electrically connected to each other. In the present embodiment, the electrode part 30a and the electrode part 30b are integrally formed. The electrode part 30a extends along the first direction D1. The electrode part 30a has a rectangular shape when viewed from the third direction D3. The electrode part 30b extends along the third direction D3. The electrode part 30b has a rectangular shape when viewed from the first direction D1. The electrode parts 30a and 30b extend along the second direction D2. The surface of the second external electrode 30 is substantially flush with each of the end surface 2b and the main surface 2d.
The first external electrode 20 and the second external electrode 30 are disposed so as to be misaligned with each other in the second direction D2 when viewed from the first direction D1. Specifically, the first external electrode 20 is disposed close to the side surface 2e when viewed from the second direction D2 and the second external electrode 30 is disposed close to the side surface 2f when viewed from the second direction D2.
In the multilayer coil component 1A, the area at which the turn 6 faces the second external electrode 30 and the area at which the turn 11 faces the first external electrode 20 are smaller than the area at which the turns 7, 8, 9, and 10 other than the turn 6 and the turn 11 face the first external electrode 20 or the second external electrode 30. The second external electrode 30 is not disposed at a position facing the turn 6. As illustrated in
The first external electrode 20 is not disposed at a position facing the turn 11. The turn 11 does not face the electrode part 20a and the electrode part 20b of the first external electrode 20. The facing area between the turn 11 and the first external electrode 20 is “0”. The turns 7, 8, 9, and 10 face the first external electrode 20. Accordingly, the area at which the turn 11 faces the first external electrode 20 is smaller than the area at which the turns 7, 8, 9, and 10 face the first external electrode 20.
As described above, in the multilayer coil component 1A according to the present embodiment, the area at which the turn 6 faces the second external electrode 30 and the area at which the turn 11 faces the first external electrode 20 are smaller than the area at which the turns 7, 8, 9, and 10 other than the turn 6 and the turn 11 face the first external electrode 20 or the second external electrode 30. In the multilayer coil component 1A according to the present embodiment, the turn 6 and the second external electrode 30 and the turn 11 and the first external electrode 20 are not disposed so as to face each other. As a result, in the multilayer coil component 1A, it is possible to reduce the parasitic capacitance that is generated (prevent parasitic capacitance from being generated) between the turn 6 and the second external electrode 30 and between the turn 11 and the first external electrode 20. As a result, in the multilayer coil component 1A, it is possible to improve the Q value while increasing the self-resonant frequency.
In the multilayer coil component 1A according to the present embodiment, the first external electrode 20 includes the electrode part 20a disposed on one end surface 2a and the electrode part 20b disposed on one main surface 2d and is disposed so as to straddle one end surface 2a and one main surface 2d. The second external electrode 30 includes the electrode part 30a disposed on the other end surface 2a and the electrode part 30b disposed on one main surface 2d and is disposed so as to straddle the other end surface 2b and one main surface 2d. The area at which the turn 6 faces the electrode part 20a and the area at which the turn 11 faces the electrode part 30a are smaller than the area at which the turn 10 other than the turn 6 and the turn 11 faces the electrode part 20a or the electrode part 30a. In a case where the multilayer coil component 1 is solder-fixed to a circuit board or the like in this configuration, solder is also formed at the electrode part 20a of the first external electrode 20 and the electrode part 30a of the second external electrode 30 positioned on the end surfaces 2a and 2b of the element body 2, and thus the multilayer coil component 1A can be firmly fixed to the circuit board or the like. In the multilayer coil component 1 having this configuration, the stray capacitance that is formed between the turn 6 and the electrode part 20a and between the turn 11 and the electrode part 30a can be reduced. Accordingly, in the multilayer coil component 1A, it is possible to improve the characteristics (self-resonant frequency and Q value) while ensuring mountability in relation to a circuit board or the like.
Although embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiments and various modifications can be made without departing from the gist of the present invention.
In the above embodiment, a form in which the turn 6 does not face the second external electrode 4 has been described as an example. Alternatively, the turn 6 may be configured to face the second external electrode 4. In this case, the area at which the turn 6 faces the second external electrode 4 may be smaller than the area at which the turns 7, 8, 9, and 10 other than the turn 6 face the second external electrode 4. The same applies to the turn 11.
In the above embodiment, a form in which the turn 6 does not face the electrode part 30a and the electrode part 30b of the second external electrode 30 has been described as an example. Alternatively, the turn 6 may be configured not to face the electrode part 30a or the electrode part 30b of the second external electrode 30. The same applies to the turn 11.
In the above embodiment, a form in which each of the first external electrode 3 and the second external electrode 4 is embedded in the element body 2 has been described as an example. Alternatively, each of the first external electrode 3 and the second external electrode 4 may be disposed on the main surface 2d of the element body 2. The same applies to the first external electrode 20 and the second external electrode 30.
In the above embodiment, a configuration in which the coil 5 includes the turns 6, 7, 8, 9, 10, and 11 has been described as an example. However, the number of turns constituting the coil is not limited thereto.
In the above embodiment, a form in which the turns 6, 7, 8, 9, 10, and 11 of the coil 5 have a rectangular outer shape as illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-020020 | Feb 2020 | JP | national |
