JP2008078234A - Laminated inductor and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated inductor that has a high initial inductance value and can improve DC superposition characteristics fully, and to provide a manufacturing method of the laminated inductor. <P>SOLUTION: The laminated inductor L1 comprises: a laminate 1 where a nonmagnetic substance 5 and a plurality of magnetic substances 4 are laminated each; a plurality of coils provided in the plurality of magnetic substances 4 each; and a connection conductor for electrically connecting each coil. In the laminated inductor L1, the nonmagnetic substance 5 is provided between respective magnetic substances 4 so that it does not come into contact with each coil, and a constituent for composing the magnetic substances 4 is not continuously diffused from one magnetic substance 4 adjacent to the nonmagnetic substance 5 to other magnetic substances 4 in the nonmagnetic substance 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multilayer inductor and a method for manufacturing the same.

As this type of multilayer inductor, it is provided with a multilayer body in which a conductor forming a coil and an insulator are laminated, and the multilayer body includes a plurality of first insulators made of a magnetic material having a high magnetic permeability, It is known that it is formed by laminating at least one or more second insulators made of a low-permeability magnetic body or non-magnetic body disposed in the inner layer of the laminate (for example, Patent Document 1). In the multilayer inductor described in Patent Document 1, conductors are formed on the first insulator and the second insulator, respectively, and the conductor is configured to sandwich the second insulator.
JP 2001-44037 A

  A multilayer inductor is required to have a good direct current superposition characteristic with little decrease in inductance value even when a large direct current is passed.

  Here, when a laminated body is formed only by an insulator made of a magnetic material with low magnetic permeability or a non-magnetic material to form a laminated inductor, the inductance value does not decrease even when a direct current is passed. Since the magnetic susceptibility is low, the initial inductance value cannot be increased. On the other hand, when a laminated body is formed only by an insulator made of a magnetic material having a high magnetic permeability to obtain a laminated inductor, the initial inductance value can be increased, but when a direct current is passed due to a magnetic saturation phenomenon. The inductance value is greatly reduced. For these reasons, the conventional multilayer inductor described in Patent Document 1 uses two types of insulators having different magnetic permeability to improve DC superposition characteristics.

  However, in the conventional multilayer inductor, the conductor is formed in the multilayer body so as to sandwich the second insulator made of a magnetic material or nonmagnetic material having a low permeability, and the conductor is in contact with the second insulator. . Therefore, when a current is passed through the conductor, the magnetic flux generated from the conductor is hindered at the portion in contact with the second insulator. As a result, the conventional multilayer inductor has a problem in that the inductance value decreases and the direct current superimposition characteristics are not sufficiently improved.

  In view of the above circumstances, an object of the present invention is to provide a multilayer inductor having a high initial inductance value and capable of sufficiently improving the DC superimposition characteristic and a method for manufacturing the same.

  The multilayer inductor according to the present invention electrically connects the multilayer body formed by laminating a non-magnetic body and a plurality of magnetic bodies, a plurality of coils respectively provided in the plurality of magnetic bodies, and the coils. A non-magnetic material provided between each magnetic material so as not to contact each coil, and a component constituting the magnetic material is separated from one adjacent magnetic material. The other magnetic material is not continuously diffused.

  In the multilayer inductor according to the present invention, each coil is provided in each magnetic body, and each magnetic body is separated by a non-magnetic body. For this reason, the number of turns of each coil existing in each magnetic body is reduced and current flows through the coil as compared with the case where the multilayer inductors are all formed of a magnetic body and the coil is provided inside the multilayer inductor. The magnitude of the generated magnetic field is reduced. As a result, magnetic saturation is suppressed in each magnetic body, and even when a large current is passed through the multilayer inductor according to the present invention, a decrease in inductance value can be suppressed, and direct current superposition characteristics can be improved. In addition, in the multilayer inductor according to the present invention, each coil does not come into contact with the nonmagnetic material. For this reason, the magnetic flux generated in each coil is hardly disturbed by the non-magnetic material. As a result, the initial inductance value of the multilayer inductor can be increased. Furthermore, in the multilayer inductor according to the present invention, in the non-magnetic material, the components constituting the magnetic material are continuously diffused from the interface with one magnetic material adjacent to the non-magnetic material to the interface with the other magnetic material. Not done. For this reason, since the substantial nonmagnetic body area | region can be ensured, without making the whole nonmagnetic body into a magnetic body with a diffusion component, the magnetic flux which generate | occur | produces in each coil can be interrupted | blocked reliably. As a result, a decrease in the inductance value can be suppressed, and further, the direct current superimposition characteristics can be improved.

  Moreover, it is preferable that the thickness of a nonmagnetic material is 10 micrometers-28 micrometers. With this configuration, it is possible to secure a necessary and sufficient area in which the components constituting the magnetic material are not diffused, that is, a substantially non-magnetic material area, so that a decrease in inductance value is suppressed, and further, direct current superposition is performed. The characteristics can be improved.

  In addition, the thickness of the outermost layer of the magnetic material in contact with the nonmagnetic material is preferably thicker than the thickness of the nonmagnetic material. If comprised in this way, since the magnetic flux density by the magnetic flux which generate | occur | produces in each coil in the outermost layer of the magnetic body which contact | connects a nonmagnetic material can be reduced, and a magnetic saturation can be relieved, it can aim at the improvement of a DC superposition characteristic further. . Here, the outermost layer of the magnetic body is formed between the conductor pattern formed on the outermost side among the conductor patterns forming the coil provided in the magnetic body and the non-magnetic body facing the conductor pattern. It refers to the magnetic part that has been made. The outermost layer of the magnetic material makes it possible to form a self-loop of the coil.

  The connecting conductor is preferably a coil formed in a non-magnetic body and having a turn number of 1/2 or more. If comprised in this way, since an inductance value can be obtained also from the coil provided in the nonmagnetic body, the initial inductance value of a multilayer inductor can be further increased.

  A method for manufacturing a multilayer inductor according to the present invention is a method for manufacturing a multilayer inductor having a plurality of magnetic bodies provided with coils and a non-magnetic body provided between the magnetic bodies, A step of forming a magnetic green layer, a step of forming a conductor pattern on the magnetic green layer, a step of repeating the respective steps to form a magnetic green laminate, and a first non-magnetic green A step of forming a layer and a step of forming a second non-magnetic green layer, and a step of forming a non-magnetic green laminate on the magnetic green laminate.

  In the method for manufacturing a multilayer inductor according to the present invention, the step of forming the first nonmagnetic green layer in the step of forming the nonmagnetic green multilayer that becomes a nonmagnetic material after firing, and the first nonmagnetic material Forming a second non-magnetic layer on the green layer. For this reason, it is possible to ensure the necessary thickness of the nonmagnetic material. As a result, a decrease in inductance value can be suppressed, and a multilayer inductor having good direct current superposition characteristics can be obtained.

  Moreover, it is preferable that the thickness of a nonmagnetic green laminated body is 12 micrometers-34 micrometers. If comprised in this way, necessary and sufficient thickness of a nonmagnetic material can be ensured reliably.

  Further, it is preferable that the step of forming the nonmagnetic green laminate includes a step of forming a conductor pattern on the first nonmagnetic green layer. If comprised in this way, since a coil can be formed in a nonmagnetic body, since an inductance value can be obtained also from this coil, a multilayer inductor with a still higher initial inductance value can be obtained.

  According to the present invention, it is possible to provide a multilayer inductor having a high initial inductance value and capable of sufficiently improving the DC superposition characteristics and a method for manufacturing the same.

  The knowledge of the present invention can be easily understood by considering the following detailed description with reference to the accompanying drawings shown for illustration only. Subsequently, embodiments of the present invention will be described with reference to the accompanying drawings. Where possible, the same parts are denoted by the same reference numerals, and redundant description is omitted.

  A multilayer inductor according to an embodiment of the present invention will be described with reference to the drawings. In the description, the words “up”, “right”, and “left” may be used in the description, which correspond to the upward, right, and left directions in each figure. .

  Next, the configuration of the multilayer inductor L1 according to the embodiment will be described with reference to FIGS. FIG. 1 is a perspective view of a multilayer inductor according to the present invention. FIG. 2 is a diagram for explaining a cross-sectional configuration of the multilayer inductor according to the embodiment. The multilayer inductor L1 according to the embodiment is formed by a printing lamination method described later.

  As shown in FIG. 1, the multilayer inductor L <b> 1 includes a substantially rectangular parallelepiped multilayer body 1 and a pair of terminal electrodes 2 and 3 formed on both end surfaces of the multilayer body 1 in the longitudinal direction. The bottom surface of the multilayer inductor L1 is a surface facing the external substrate when the multilayer inductor L1 is mounted on an external substrate (not shown).

  The laminated body 1 includes a plurality of (four in the present embodiment) magnetic bodies 4 formed by a printing lamination method in which magnetic green layers A1 to A15 are screen-printed in a predetermined pattern and sequentially laminated, and a non-magnetic body. The green layers B <b> 1 to B <b> 6 are configured by a plurality of (three in the present embodiment) nonmagnetic materials 5 formed by a printing lamination method in which screen printing is performed in a predetermined pattern and sequentially laminated.

  Each magnetic body 4 has coils 10 to 13 made of a plurality of conductor patterns therein, so that each coil 10 to 13 does not contact the nonmagnetic body 5. Each magnetic body 4 is formed by firing after magnetic green layers A1 to A15 are printed and laminated as will be described later, and functions as an insulator having electrical insulation. As the magnetic green layers A1 to A15, ferrite (for example, Ni—Cu—Zn based ferrite) can be used.

  Each non-magnetic body 5 is positioned so as to be sandwiched between the respective magnetic bodies 4 and has conductor patterns C4, C8, and C12 that function as connecting conductors that electrically connect the coils 10 to 13, respectively. ing. The conductor patterns C4, C8, and C12 are formed as 1/2 turn patterns, and also function as coils. Each nonmagnetic body 5 is formed by firing after the nonmagnetic green layers B1 to B6 are printed and laminated as described later, and functions as an insulator having electrical insulation. As the nonmagnetic green layers B1 to B6, ferrite (for example, Cu—Zn ferrite) can be used.

Further, each non-magnetic body 5 (5 ₁ ) has a component (for example, Ni) constituting the magnetic body 4 from the interface S1 with the adjacent one of the magnetic bodies 4 (4 ₁ ) to the other magnetic body 4 (4 ₂ ) is not continuously diffused across the interface S2. A multilayer inductor is manufactured by simultaneously firing a coil, a magnetic body, and a non-magnetic body. At the interface between the magnetic body and the non-magnetic body, the constituents of the magnetic body may diffuse into the non-magnetic body during the firing process, and the non-magnetic body may become a magnetic body (for example, Cu-Zn based ferrite Ni-Cu-Zn based ferrite). When the diffusion of the components that make up this magnetic material progresses and there is a portion that is continuously diffusing from the interface with one adjacent magnetic material to the interface with the other magnetic material, that portion becomes a magnetic material. As a result, the interruption of the magnetic flux becomes insufficient, and the improvement of the DC superimposition characteristic becomes insufficient. In the present embodiment, the component in which the magnetic body 4 is continuously diffused from the interface S1 with _one magnetic body 4 (4 ₁ ) to the interface S2 with the other magnetic body 4 (4 ₂ ). Does not exist. Therefore, a substantial non-magnetic region can be secured, and the direct current superimposition characteristics can be improved by reliably blocking the magnetic flux.

  The thickness of each nonmagnetic material 5 is preferably 10 μm to 28 μm, and particularly preferably 18 μm to 20 μm. If this thickness is too thin, the components constituting the magnetic body 4 diffuse toward the inside of the non-magnetic body, and the region that functions substantially as a non-magnetic body becomes extremely thin or the region cannot be secured, so The superimposition characteristics cannot be improved. Further, the variation in the initial inductance value among the individual multilayer inductors increases, and the defect rate increases. On the other hand, if this thickness is too thick, the volume occupied by the nonmagnetic material of the multilayer inductor becomes relatively large, and the initial inductance value decreases. In addition, since the non-magnetic material has magnetism at a low temperature, the rate of change of the inductance value at a low temperature increases, and the temperature characteristics particularly at a low temperature deteriorate.

The thickness t1 of the outermost layer 4a of the non-magnetic material 5 _{(5 1)} in contact with the magnetic body 4 _{(4 1)} is configured larger than the thickness t2 of the non-magnetic body 5. With this configuration, the magnetic flux density by the magnetic flux generated by each coil in the outermost layer 4a of the non-magnetic material 5 (5 ₁₎ in contact with the magnetic body 4 (4 ₁₎ can be relaxed reduced magnetic saturation, Furthermore, the direct current superimposition characteristics can be improved.

  The coils 10 to 12 have conductor patterns C1 to C3, conductor patterns C5 to C7, or conductor patterns C9 to C11 printed and laminated, respectively, and are adjacent to each other in the stacking direction, the conductor patterns C1 to C3, the conductor patterns C5 to C7, or the conductors. The end portions of the patterns C9 to C11 are formed by being electrically connected to each other. The coil 13 is formed by superimposing and superimposing conductor patterns C13 and C14, and electrically connecting ends of the conductor patterns C13 and C14 adjacent in the stacking direction. Further, the coils 10 to 13 adjacent in the stacking direction are electrically connected to each other by the conductor patterns C4, C8, and C12. Furthermore, a lead-out portion C1a is integrally formed at the other end opposite to the one end electrically connected to the conductor pattern C2 of the conductor pattern C1 which is a part of the coil 10. The lead-out part C1a is drawn out to the side surface located in the longitudinal direction of the multilayer body 1, and is electrically connected to the terminal electrode 2. Further, a lead-out portion C14a is integrally formed at the other end opposite to the one end electrically connected to the conductor pattern C13 of the conductor pattern C14 which is a part of the coil 13. The lead-out part C <b> 14 a is drawn out to the side surface located in the longitudinal direction of the multilayer body 1 and is electrically connected to the terminal electrode 3.

  As described above, in the multilayer inductor according to the present embodiment, the coils 10 to 13 are provided inside the magnetic bodies 4, and the magnetic bodies 4 are separated by the nonmagnetic bodies 5. For this reason, the number of turns of each of the coils 10 to 13 existing in each magnetic body 4 is reduced to about 1 to 3 turns, respectively, and the laminated body 1 is entirely formed of a magnetic body, and a coil is provided therein. As compared with the case where the current is flowing, the magnitude of the magnetic field generated by the current flowing through each of the coils 10 to 13 is reduced. As a result, the magnetic saturation is suppressed in each magnetic body 4, and even when a large current is passed through the multilayer inductor L1 according to the present embodiment, a decrease in inductance value can be suppressed, and the DC superposition characteristics can be improved. It can be planned. In the present embodiment, the coils 10 to 13 are not in contact with the nonmagnetic material 5. For this reason, the magnetic flux F generated around each of the coils 10 to 13 when a direct current is passed through the multilayer inductor L1 is hardly disturbed by the nonmagnetic material 5 (see FIG. 2). As a result, the initial inductance value of the multilayer inductor L1 can be increased. Furthermore, in the present embodiment, in the non-magnetic body 5, the components constituting the magnetic body 4 continue from the interface with one magnetic body 4 adjacent to the non-magnetic body 5 to the interface with the other magnetic body 4. Is not spreading. For this reason, since the substantial nonmagnetic material area | region can be ensured, without making the whole nonmagnetic material 5 magnetic by a diffusion component, the magnetic flux which generate | occur | produces in each coil can be interrupted | blocked reliably. As a result, a decrease in the inductance value can be suppressed, and further, the direct current superimposition characteristics can be improved.

  In the multilayer inductor according to the present embodiment, the conductor patterns C4, C8, and C12 of 1/2 turn are connection conductors that electrically connect the coils 10, 11, 12, and 13, respectively. The initial inductance value of the multilayer inductor L1 can be further increased by the coils 4, 8, and 12 provided inside the nonmagnetic material 5.

  Next, a method for manufacturing the multilayer inductor L1 having the above-described configuration will be described with reference to FIGS. 3 to 16 are perspective views showing one step of the manufacturing process of the multilayer inductor in the printing lamination method.

  First, magnetic powders such as the Ni—Cu—Zn-based ferrite described above, a binder, a solvent, and the like are kneaded to generate a magnetic paste that is a raw material for the magnetic green layers A1 to A15. Further, the nonmagnetic powder such as the Cu—Zn-based ferrite described above, a binder, a solvent, and the like are kneaded to generate a nonmagnetic paste serving as a raw material for the nonmagnetic green layers B1 to B6. Furthermore, a metal paste such as Ag, a binder and materials are kneaded to produce a conductor paste as a raw material for the conductor patterns C1 to C14 and the lead-out portions C1a and C14a.

  Next, the magnetic paste obtained as described above is printed in a sheet shape to form the magnetic green layer A1 (see FIG. 3). A conductive paste is printed on the surface of the magnetic green layer A1 in a substantially L shape to form a conductor pattern C1 corresponding to approximately 1/2 turn of the coil 10, and is drawn out to the edge of the magnetic green layer A1. Thus, the conductor paste is printed in a substantially rectangular shape to form the lead-out portion C1a integrally with the conductor pattern C1 (see FIG. 4). Subsequently, a part of the conductor pattern C1 is exposed on the surface, and a magnetic paste is printed so as to cover a substantially right half of the surface of the intermediate body, thereby forming a magnetic green layer A2 (see FIG. 5).

  Next, a conductor paste is printed in a substantially L shape so that one end of the conductor pattern C2 overlaps the other end opposite to the one end where the lead-out portion C1a of the conductor pattern C1 is formed. A conductor pattern C2 corresponding to approximately 1/2 turn of the coil 10 is formed on A2 (see FIG. 6). Then, a part of the conductor pattern C2 is exposed on the surface, and a magnetic paste is printed so as to cover a region of about 2/3 on the left side of the surface of the intermediate body to form a magnetic green layer A3 (FIG. 7). Furthermore, a conductor paste is printed in a substantially L shape so that one end of the conductor pattern C3 overlaps the other end of the conductor pattern C2 opposite to the one connected to the conductor pattern C1, and the magnetic green layers A2, A3 A conductor pattern C3 corresponding to approximately ½ turn of the coil 10 is formed thereon (see FIG. 8). Subsequently, a part of the conductor pattern C3 is exposed on the surface, and a magnetic paste is printed so as to cover a substantially 2/3 region on the right side of the surface of the intermediate to form a magnetic green layer A4, A magnetic green laminate that becomes the magnetic body 4 after firing is obtained (see FIG. 9).

  Next, a nonmagnetic paste is printed so as to overlap the magnetic green layer A4 exposed on the outermost surface of the magnetic green laminate, and the nonmagnetic green layer B1 (first nonmagnetic material) is printed. Green layer) is formed (see FIG. 10). Further, a conductor paste is printed in a substantially L shape so that one end of the conductor pattern C4 overlaps the other end of the conductor pattern C3 opposite to the one connected to the conductor pattern C2, and on the magnetic green layer A3 and A conductor pattern C4 (corresponding to approximately 1/2 turn of the coil) is formed on the nonmagnetic green layer B1 (see FIG. 11). Then, a part of the conductor pattern C4 is exposed on the surface, and a nonmagnetic paste is printed so as to cover a region of about 2/3 on the left side of the surface of the intermediate body, and the nonmagnetic green layer B2 (second Nonmagnetic green layer) is formed to obtain a nonmagnetic green laminate that becomes the nonmagnetic material 5 after firing (see FIG. 12). Here, the thickness of the non-magnetic green laminate is preferably 12 μm to 34 μm, and particularly preferably 21 μm to 24 μm. When this thickness is less than 12 μm, when the laminated inductor is fired, a component constituting the magnetic material diffuses toward the inside of the nonmagnetic material, and substantially functions as a nonmagnetic material. Is extremely thin or the area cannot be secured, and the direct current superimposition characteristics cannot be improved. On the other hand, if the thickness is greater than 34 μm, the volume occupied by the non-magnetic material when the multilayer inductor is formed becomes relatively large, and the initial inductance value decreases.

  Next, a magnetic paste is printed so as to overlap the nonmagnetic green layer B2 exposed on the surface of the nonmagnetic green laminate, thereby forming the magnetic green layer A5 (see FIG. 13). Subsequently, a conductor paste is printed in a substantially L shape so that one end of the conductor pattern C5 overlaps the other end of the conductor pattern C4 opposite to the one connected to the conductor pattern C3, and the nonmagnetic green layer B1 A conductor pattern C5 is formed on the upper and magnetic green layer A5 (see FIG. 14). Then, a part of the conductor pattern C5 is exposed on the surface, and a magnetic paste is printed so as to cover a substantially 2/3 region on the right side of the surface of the intermediate to form a magnetic green layer A6 (FIG. 15). As described above, the process of forming the magnetic green layer, the conductor pattern, and the non-magnetic green layer is repeated, and finally the magnetic paste is printed on the uppermost layer to form the magnetic green layer A15 to form the green laminated layer. A body 15 is obtained (see FIG. 16).

  Subsequently, the green laminate 15 is fired in the atmosphere at a predetermined temperature (for example, about 800 to 900 ° C.) to form the laminate 1.

  Next, terminal electrodes 2 and 3 are formed on the laminate 1. Thereby, the multilayer inductor L1 is formed. The terminal electrodes 2 and 3 are each baked at a predetermined temperature (for example, about 680 to 740 ° C.) by applying an electrode paste mainly composed of silver, nickel or copper to both end faces in the longitudinal direction of the laminate 1. Further, it is formed by performing electroplating. Cu, Ni, Sn, etc. can be used for this electroplating.

  As described above, in the method for manufacturing a multilayer inductor according to this embodiment, the nonmagnetic green layer B1 (first nonmagnetic layer) is formed in the step of forming the nonmagnetic green multilayer body that becomes the nonmagnetic body 5 after firing. Forming a non-magnetic green layer B2 (second non-magnetic layer) on the non-magnetic green layer B1. For this reason, the required thickness of the nonmagnetic material 5 can be ensured reliably. As a result, a decrease in inductance value can be suppressed, and a multilayer inductor having good direct current superposition characteristics can be obtained.

  In the multilayer inductor manufacturing method according to the present embodiment, the conductor patterns C4, C8, and C12 corresponding to approximately ½ turns are formed on the nonmagnetic green layers B1, B3, and B5. The initial inductance value of the multilayer inductor L1 can be further increased.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

(Example 1)
A conductive pattern using Ni—Cu—Zn-based ferrite as the magnetic material and Cu—Zn-based ferrite as the non-magnetic material so that the total number of turns shown in FIG. A multilayer inductor was fabricated. Here, each non-magnetic material was formed by screen-printing two non-magnetic green layers to form a non-magnetic green laminate and firing. Further, the thickness of the nonmagnetic material after firing was 11 μm. Further, when the cross section of this multilayer inductor was observed with EPMA, the non-magnetic material showed that Ni, which is a constituent component of the magnetic material, diffused in the non-magnetic material in the vicinity of the interface with the magnetic material. There was no continuous diffusion from one of the adjacent magnetic materials to the other.

(Example 2)
A nonmagnetic green laminate was formed by screen-printing four nonmagnetic green layers, and the same procedure as in Example 1 was performed except that the thickness of each nonmagnetic material after firing was 18 μm. Further, when the cross-section of this multilayer inductor was observed with EPMA in the same manner as in Example 1, in the nonmagnetic material, Ni, which is a constituent component of the magnetic material, diffused into the nonmagnetic material in the vicinity of the interface with the magnetic material. However, no continuous diffusion was observed from one of the magnetic materials adjacent to the non-magnetic material to the other.

(Example 3)
Six non-magnetic green layers were screen-printed to form a non-magnetic green laminate, and the same procedure as in Example 1 was performed except that the thickness of each non-magnetic body after firing was 23 μm. Further, when the cross-section of this multilayer inductor was observed with EPMA in the same manner as in Example 1, in the nonmagnetic material, Ni, which is a constituent component of the magnetic material, diffused into the nonmagnetic material in the vicinity of the interface with the magnetic material. However, no continuous diffusion was observed from one of the magnetic materials adjacent to the non-magnetic material to the other.

Example 4
A nonmagnetic green laminate was formed by screen-printing eight nonmagnetic green layers, and the same procedure as in Example 1 was performed, except that the thickness of each nonmagnetic material after firing was 30 μm. Further, when the cross-section of this multilayer inductor was observed with EPMA in the same manner as in Example 1, in the nonmagnetic material, Ni, which is a constituent component of the magnetic material, diffused into the nonmagnetic material in the vicinity of the interface with the magnetic material. However, no continuous diffusion was observed from one of the magnetic materials adjacent to the non-magnetic material to the other.

(Comparative example)
As a comparative example, a conductive pattern using Ni—Cu—Zn ferrite as a magnetic material and Cu—Zn ferrite as a nonmagnetic material and having a total number of turns of 11.5 turns by a printing lamination method. A multilayer inductor was fabricated. Here, the structure of the multilayer inductor according to Comparative Example 1 is different from the multilayer inductor according to the embodiment shown in FIG. 1 in that no coil is formed in the nonmagnetic material. Each nonmagnetic material was formed by screen printing a nonmagnetic green layer one by one to form a nonmagnetic green laminate and firing. The thickness of each nonmagnetic material after firing was 6 μm. Further, when the cross section of the multilayer inductor was observed with EPMA, Ni as a constituent component of the magnetic material was diffused throughout the nonmagnetic material.

  With respect to the multilayer inductors according to the above-described examples and the multilayer inductors according to the comparative examples, initial inductance values, variations in inductance values, DC superimposition characteristics, and temperature characteristics of inductance values were evaluated. The evaluation results are shown in FIGS.

  FIG. 17 is a diagram showing changes in the initial inductance value (L value) due to changes in the thickness of the nonmagnetic material. As shown in FIG. 17, the inductance value decreases as the thickness of the non-magnetic material increases, but this is a level that does not cause any problem in practice.

  FIGS. 18 and 19 are diagrams showing changes in the inductance value due to changes in the thickness of the non-magnetic material. Here, in FIG. 18, the initial inductance value of the sample with n = 30 was measured, and the standard deviation σ was used as an index of variation. 19, σ / average value Ave. calculated based on the standard deviation σ obtained in the evaluation of FIG. Was used as an indicator of variation. As shown in FIG. 18, the standard deviation σ of the multilayer inductors according to Example 1 (nonmagnetic material thickness 11 μm), Example 2 (nonmagnetic material thickness 18 μm), and Example 3 (nonmagnetic material thickness 23 μm) 0.27, 0.20, 0.18 μH) is smaller than the standard deviation σ (0.76 μH) of the multilayer inductor according to the comparative example (non-magnetic thickness 6 μm). The multilayer inductors according to the second and third embodiments have less variation than the multilayer inductor according to the comparative example. Similarly, as shown in FIG. 19, σ / average value Ave. of the multilayer inductors according to Example 1, Example 2, and Example 3. (About 9%) represents σ / average value Ave. of the multilayer inductor according to the comparative example. The value is smaller than (17.5%), and the multilayer inductors according to Example 1, Example 2, and Example 3 have less variation than the multilayer inductor according to the comparative example.

  Moreover, FIG. 20 is a figure which shows the change of the direct current | flow superimposition characteristic by the thickness change of a nonmagnetic material. Here, the direct current superimposition characteristic is based on the current value at which the inductance (L) value is reduced by 20% with respect to the initial inductance value. The higher the current value, the better the DC superposition characteristics. As shown in FIG. 20, the multilayer inductor according to the comparative example has a low current of 40 mA, whereas the multilayer inductors according to the first, second, and third examples have high currents of 100, 160, and 200 mA, respectively. The multilayer inductors according to Example 1, Example 2, and Example 3 have good direct current superposition characteristics.

  FIG. 21 is a diagram showing a change in the temperature characteristic of the inductance value due to a change in the thickness of the magnetic material. Here, for the temperature characteristics, an inductance value of −40 ° C. was measured, and an inductance value change rate based on the inductance value of 25 ° C. was used as an index. A smaller change rate indicates better temperature characteristics. As shown in FIG. 21, the rate of change increases as the thickness of the nonmagnetic material increases. In the multilayer inductor according to Example 4 (non-magnetic material thickness 30 μm), the rate of change is a relatively large value of 34%, but this is a practically acceptable level.

1 is a perspective view of a multilayer inductor according to the present invention. It is a figure for demonstrating the cross-sectional structure of the multilayer inductor which concerns on embodiment. It is a perspective view which shows 1 process of the manufacturing process of the multilayer inductor which concerns on embodiment. FIG. 4 is a perspective view showing a step subsequent to FIG. 3. FIG. 5 is a perspective view showing a step subsequent to FIG. 4. FIG. 6 is a perspective view showing a step subsequent to FIG. 5. FIG. 7 is a perspective view showing a step subsequent to FIG. 6. FIG. 8 is a perspective view showing a step subsequent to FIG. 7. FIG. 9 is a perspective view showing a step subsequent to FIG. 8. FIG. 10 is a perspective view showing a step subsequent to FIG. 9. FIG. 11 is a perspective view showing a step subsequent to FIG. 10. FIG. 12 is a perspective view showing a step subsequent to FIG. 11. FIG. 13 is a perspective view showing a step subsequent to FIG. 12. FIG. 14 is a perspective view showing a step subsequent to FIG. 13. FIG. 15 is a perspective view showing a step subsequent to FIG. 14. FIG. 16 is a perspective view showing a step subsequent to FIG. 15. It is a figure which shows the change of the inductance value by the thickness change of a nonmagnetic material. It is a figure which shows the change of the inductance value variation by the thickness change of a nonmagnetic material. It is a figure which shows the change of the inductance value variation by the thickness change of a nonmagnetic material. It is a figure which shows the change of the direct current | flow superimposition characteristic by the thickness change of a nonmagnetic material. It is a figure which shows the change of the temperature characteristic of the inductance value by the thickness change of a magnetic body.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Laminated body, 2, 3 ... Terminal electrode, 4 ... Magnetic body, 5 ... Nonmagnetic body, 10-13 ... Coil, 15 ... Green laminated body, A1-A15 ... Magnetic body green layer, B1-B6 ... Nonmagnetic Body green layer, C1 to C14 ... conductor pattern, L1 ... multilayer inductor.

Claims (7)

A non-magnetic material and a laminate in which a plurality of magnetic materials are laminated, and
A plurality of coils respectively provided in the plurality of magnetic bodies;
A laminated inductor comprising a connection conductor for electrically connecting the coils,
The non-magnetic body is provided between the magnetic bodies so as not to contact the coils, and in the non-magnetic body, a component constituting the magnetic body is one of the magnets adjacent to the non-magnetic body. A multilayer inductor characterized by not continuously diffusing from one body to the other magnetic body. The multilayer inductor according to claim 1, wherein the nonmagnetic material has a thickness of 10 μm to 28 μm. 3. The multilayer inductor according to claim 1, wherein a thickness of an outermost layer of the magnetic material in contact with the nonmagnetic material is thicker than a thickness of the nonmagnetic material. The multilayer inductor according to any one of claims 1 to 3, wherein the connection conductor is a coil having a number of turns of 1/2 or more formed in the non-magnetic body. A method of manufacturing a multilayer inductor having a plurality of magnetic bodies provided with coils and a non-magnetic body provided between the magnetic bodies,
A step of forming a magnetic green layer, and a step of forming a conductor pattern on the magnetic green layer, and repeating each step to form a magnetic green laminate,
A step of forming a first nonmagnetic green layer and a step of forming a second nonmagnetic green layer, and forming a nonmagnetic green laminate on the magnetic green laminate;
A method for manufacturing a multilayer inductor, comprising: 6. The method of manufacturing a multilayer inductor according to claim 5, wherein the non-magnetic green multilayer body has a thickness of 12 [mu] m to 34 [mu] m. 7. The multilayer inductor according to claim 5, wherein the step of forming the non-magnetic green laminate includes a step of forming a conductor pattern on the first non-magnetic green layer. 8. Production method.

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