This application claims priority to Japanese Patent Application No. 2021-001494 filed on Jan. 7, 2021, the entire contents of which are incorporated by reference herein.
The present invention relates to a multilayer inductor and a mounting structure of a multilayer inductor.
In the related art, as a multilayer inductor, those described in Japanese Unexamined Patent Publication No. H10-144526 are known. This multilayer inductor includes an element body formed by stacking a plurality of layers made of an insulator in a stacking direction, terminal electrodes provided on the end surfaces and side surfaces of the element body, and a linear conductor portion provided in the element body and extending in a longitudinal direction of the element body. The conductor portion has a constant width over the entire longitudinal direction.
Herein, in the multilayer inductor as described above, a wraparound portion is formed in which the terminal electrode wraps around from the end surface of the element body to the side surface. In this case, stray capacitance is generated between the wraparound portion of the terminal electrode and the linear conductor portion. In some case, due to the influence of such stray capacitance, the self-resonant frequency (SRF) of the multilayer inductor may be decreased.
An object of the present invention is to provide a multilayer inductor capable of improving a self-resonant frequency and a mounting structure of the multilayer inductor.
A multilayer inductor according to the present invention includes: an element body formed by stacking a plurality of layers of insulators in a stacking direction; a terminal electrode provided on at least one side surface of the element body; and a linear conductor portion provided in the element body and extending in a first direction, wherein, as viewed from a second direction perpendicular to the first direction, the conductor portion has a first portion in a region overlapping the terminal electrode and a second portion in a region not overlapping the terminal electrode, and wherein a width of the first portion as viewed from the second direction is smaller than a width of the second portion.
In the multilayer inductor according to the present invention, the linear conductor portion has a first portion in a region overlapping the terminal electrode as viewed from the second direction. The first portion is a portion where stray capacitance is likely to be generated with the terminal electrode on the side surface. Herein, the width of the first portion as viewed from the second direction is smaller than the width of the second portion of the region not overlapping the terminal electrode. Accordingly, the stray capacitance between the first portion and the terminal electrode on the side surface can be reduced. From the above, the self-resonant frequency of the multilayer inductor can be improved.
A width of the first portion as viewed from a third direction perpendicular to the first direction and the second direction may be smaller than the width of the second portion. In this case, the width of the second portion as viewed from the third direction can be relatively increased. Accordingly, the cross-sectional area of the second portion not overlapping the terminal electrode on the side surface can be increased, so that DC resistance (Rdc) of the conductor portion can be reduced.
As viewed from the first direction, the conductor portion has a shape spreading in a third direction perpendicular to the first direction and the second direction, and a mark for identifying the posture of the conductor portion may be formed in the element body. In this case, when the multilayer inductor is mounted on a mounting board, the posture of the conductor portion spreading in the third direction can be set to a desired state by checking the mark.
A mounting structure of a multilayer inductor according to the present invention includes the above-mentioned multilayer inductor and a mounting board on which the multilayer inductor is mounted via the terminal electrode, wherein the multilayer inductor is mounted so that the conductor portion rises from a mounting surface of the mounting board as viewed from the first direction.
In the mounting structure of the multilayer inductor according to the present invention, since the multilayer inductor is mounted so that the conductor portion rises from the mounting surface of the mounting board, it is possible to reduce the stray capacitance generated between the conductor portion and the mounting board. Accordingly, the self-resonant frequency of the multilayer inductor can be improved.
According to the present invention, it is possible to provide a multilayer inductor capable of improving a self-resonant frequency and a mounting structure of the multilayer inductor.
A multilayer inductor according to a first embodiment of the present invention will be described with reference to
As illustrated in
The element body 2 has side surfaces 2a and 2b facing in the stacking direction Z, end surfaces 2c and 2d facing in the longitudinal direction Y, and side surfaces 2e and 2f facing in the lateral direction X. The side surface 2a is disposed on the negative side in the stacking direction Z, and the side surface 2b is disposed on the positive side in the stacking direction Z. The end surface 2c is disposed on the negative side in the longitudinal direction Y, and the end surface 2d is disposed on the positive side in the longitudinal direction Y. The side surface 2e is disposed on the negative side in the lateral direction X, and the side surface 2f is disposed on the positive side in the lateral direction X. It is noted that the material of the element body 2 is not particularly limited, and an optimum material may be adopted depending on the application of the multilayer inductor 1, but for example, glass, ceramic or the like may be adopted. Although not particularly limited, the dimension of the element body 2 in the longitudinal direction Y is set to 0.3 to 1.6 mm, the dimension in the lateral direction X is set to 0.3 to 1.6 mm, and the dimension in the stacking direction Z is set to 0.3 to 1 mm.
The terminal electrodes 3 and 4 are electrodes formed in the vicinity of the end surfaces 2c and 2d of the element body 2. The terminal electrodes 3 and 4 are adhered to terminals of a mounting board when the multilayer inductor 1 is mounted. The terminal electrode 3 is provided so as to cover the entire surface of the end surface 2c and to cover the regions of the side surfaces 2a, 2b, 2e, and 2f in the vicinity of the end surface 2c. The terminal electrode 3 is formed so as to wrap around from the end surface 2c to the side surfaces 2a, 2b, 2e, and 2f. The terminal electrode 4 is provided so as to cover the entire surface of the end surface 2d and to cover the regions of the side surfaces 2a, 2b, 2e, and 2f in the vicinity of the end surface 2d. The terminal electrode 4 is formed so as to wrap around from the end surface 2d to the side surfaces 2a, 2b, 2e, and 2f. The terminal electrodes 3 and 4 are disposed so as to be separated from each other in the longitudinal direction Y. Accordingly, the regions of the side surfaces 2a, 2b, 2e, and 2f in the vicinity of the center in the longitudinal direction Y are in a state exposed from the terminal electrodes 3 and 4. The materials of the terminal electrodes 3 and 4 are not particularly limited, and an optimum material may be adopted depending on the application of the multilayer inductor 1, but for example, silver, copper, or the like may be adopted. The terminal electrodes 3 and 4 may be formed by a dip method in which the end portion of the element body 2 is immersed in a paste of the electrode. However, the method for forming the terminal electrodes 3 and 4 is not particularly limited, and the terminal electrodes 3 and 4 may be formed by another method such as printing an electrode paste on the end portion of the element body 2.
Next, the internal structure of the element body 2 will be described with reference to
The negative end of the conductor portion 6 in the longitudinal direction Y is exposed to the end surface 2c of the element body 2. Accordingly, the conductor portion 6 is electrically connected to a main body portion 3a of the terminal electrode 3 that covers the end surface 2c. The positive end of the conductor portion 6 in the longitudinal direction Y is exposed to the end surface 2d of the element body 2. Accordingly, the conductor portion 6 is electrically connected to a main body portion 4a of the terminal electrode 4 that covers the end surface 2d. It is noted that, in the present embodiment, since the conductor portion 6 extends in the longitudinal direction Y, the longitudinal direction Y corresponds to the “first direction” in the claims. Further, the stacking direction Z corresponds to the “second direction” in the claims. Further, the lateral direction X corresponds to the “third direction” in the claims.
Herein, the element body 2 is formed by stacking a plurality of layers 20 in the stacking direction Z (refer to
Next, a shape of the conductor portion 6 based on a positional relationship with the terminal electrodes 3 and 4 will be described. As illustrated in
As viewed from the stacking direction Z, the conductor portion 6 overlaps the terminal electrodes 3 and 4 in the regions E1 and E2 and does not overlap the terminal electrodes 3 and 4 in the region E3. In contrast, as viewed from the stacking direction Z, the conductor portion 6 has first portions 11 and 12 in the regions E1 and E2 overlapping the terminal electrodes 3 and 4 in the regions E1 and E2 and a second portion 10 in the region E3 not overlapping the terminal electrodes 3 and 4. In the present embodiment, the boundary between the first portion 11 and the second portion 10 coincides with the boundary L1 between the region E1 and the region E3. Further, the boundary between the first portion 12 and the second portion 10 coincides with the boundary L2 between the region E2 and the region E3. However, a portion of the first portions 11 and 12 may extend to the regions E3, and the second portion 10 may extend to the regions E1 and E2.
As illustrated in
It is noted that, as illustrated in
Next, the function and effect of the multilayer inductor 1 according to the present embodiment will be described.
In the multilayer inductor 1 according to the present embodiment, the linear conductor portion 6 has the first portions 11 and 12 in the regions E1 and E2 overlapping the terminal electrodes 3 and 4 as viewed from the stacking direction Z. The first portion 11 is a portion where stray capacitance is likely to be generated between the side surfaces 2a and 2b and the wraparound portions 3b and 3c of the terminal electrode 3. The first portion 12 is a portion where the stray capacitance is likely to be generated between the side surfaces 2a and 2b and the wraparound portions 4b and 4c of the terminal electrode 4. Herein, the width of the first portions 11 and 12 as viewed from the stacking direction Z is smaller than the width of the second portion 10 of the region E3 not overlapping the terminal electrodes 3 and 4. Accordingly, the stray capacitance between the first portions 11 and 12 and the side terminal electrodes 3 and 4 can be reduced. From the above, the self-resonant frequency of the multilayer inductor 1 can be improved.
It is noted that the structures of the first portions 11 and 12 and the second portion 10 of the conductor portion 6 may be realized by decreasing the width of the portion corresponding to the first portions 11 and 12 in the conductor portion (conductor pattern having a constant width over the entire region in the longitudinal direction Y) in the related art, may be realized by increasing the width of the portion corresponding to the second portion 10, or may be realized by both methods. When the width of the portion corresponding to the first portions 11 and 12 is decreased, the stray capacitance with the terminal electrodes 3 and 4 can be reduced as compared with the conductor portion in the related art. When the width of the portion corresponding to the second portion 10 is increased, DC resistance of the conductor portion 6 can be reduced. When trying to obtain the same DC resistance with the conductor portion in the related art, since the width of the entire conductor portion is increased, as a result, the stray capacitance with the terminal electrodes 3 and 4 is increased. When the width of the portion corresponding to the second portion 10 is increased, the DC resistance can be reduced while suppressing such an increase in stray capacitance. That is, with respect to the obtained DC resistance, the self-resonant frequency of the multilayer inductor 1 can be relatively improved as compared with that in the related art.
As viewed from the longitudinal direction Y, the conductor portion 6 has a shape spreading in the lateral direction X perpendicular to the longitudinal direction Y and the stacking direction Z, and the mark 30 for identifying the posture of the conductor portion 6 may be formed on the element body 2. In this case, when the multilayer inductor 1 is mounted on the mounting board, the posture of the conductor portion 6 spreading in the lateral direction X can be set to a desired state by checking the mark 30.
Next, a multilayer inductor 1 according to a second embodiment will be described with reference to
In the multilayer inductor 1 according to the second embodiment, as illustrated in
The dimensional relationship as described above can be realized by increasing the thickness of the conductor pattern of the second portion 10 as compared with the first embodiment. For example, when printing a conductor paste on a sheet body of the layer 20A before sintering, only the portion corresponding to the second portion 10 may be printed a plurality of times. Accordingly, as illustrated in
In the multilayer inductor 1 according to the second embodiment, the width of the second portion 10 as viewed from the lateral direction X can be relatively increased. Accordingly, the cross-sectional area of the second portion not overlapping the terminal electrode on the side surface can be increased, so that the DC resistance (Rdc) of the conductor portion can be reduced.
When the multilayer inductor 1 according to each embodiment is mounted on the mounting board, even though the mounting is performed in a state where the lateral direction X (that is, the direction in which the conductor portion 6 spreads) and a mounting surface of the mounting board are parallel to each other, a sufficient effect can be obtained. However, by adopting a mounting structure as illustrated in
Specifically, as illustrated in
In the mounting structure 100 of the multilayer inductor 1, since the multilayer inductor 1 is mounted so that the conductor portion 6 rises from the mounting surface 150a of the mounting board 150, the stray capacitance generated between the conductor portion 6 and the mounting board 150 can be reduced. Accordingly, the self-resonant frequency of the multilayer inductor 1 can be improved.
It is noted that, when the multilayer inductor 1 is mounted so as to have such a positional relationship, it is effective to grasp the posture of the conductor portion 6 inside the element body 2 by referring to the mark 30 (refer to
The present invention is not limited to the above-described embodiments.
For example, the shape of the element body 2 and the shapes of the terminal electrodes 3 and 4 may be changed as appropriate. Along with this, the shapes and ratios of the first portions 11 and 12 and the second portion 10 are also appropriately changed.
In the above-described embodiment, the terminal electrodes 3 and 4 have main body portions 3a and 4a and four wraparound portions, respectively. However, the terminal electrodes 3 and 4 may be provided on at least one side surface of the four side surfaces 2a, 2b, 2e, and 2f, and the portions corresponding to the other side surface and the end surface may be omitted. It is noted that, when the terminal electrodes 3 and 4 are provided only on the side surface, the conductor portion 6 and the terminal electrodes 3 and 4 may be connected via through-hole conductor or the like.
Number | Date | Country | Kind |
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2021-001494 | Jan 2021 | JP | national |