JP2005093971A - Multilayer ceramic electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance design flexibility by reducing a mutual diffusion region without damaging the bonding strength at the interface. <P>SOLUTION: A interlayer 3 is intervened between a first magnetic material layer 1 and second magnetic material layer 2, and the interlayer 3 is made of the first material constituting the first magnetic material layer 1, added with at least one of an oxide and a nitride. The oxide and nitride are formed of materials, such as Al<SB>2</SB>O<SB>3</SB>, SiO<SB>2</SB>, MgO, Si<SB>3</SB>N<SB>4</SB>, or AlN, which has a higher sintering temperature than that of the first magnetic material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a multilayer ceramic electronic component, and more particularly to a multilayer ceramic electronic component such as a multilayer inductor, a multilayer impedancer, a multilayer capacitor, and a multilayer LC component in which ceramic layers having different compositions are stacked.

  2. Description of the Related Art Multilayer ceramic electronic components in which ceramic layers having different compositions are laminated are widely used today for various applications such as noise countermeasures.

  By the way, when ceramic layers having different compositions are simply laminated and fired as in this type of multilayer ceramic electronic component, there is a drawback that the ceramic materials diffuse to each other during firing, leading to deterioration of the characteristics of the ceramic layer.

  Therefore, conventionally, as shown in FIG. 3, a multilayer ceramic electronic component (multilayer inductor) in which an intermediate layer 53 made of a nonmagnetic material is integrally interposed between magnetic layers 51 and 52 having different magnetic permeability has been proposed. (Patent Document 1).

  This patent document 1 discloses a high magnetic permeability first magnetic layer 51 in which a first coil conductor 55 is embedded, and a low magnetic permeability second magnetic layer 52 in which a second coil conductor 56 is embedded. The first coil conductor 55 and the second coil conductor 56 are connected by the connection conductor 57, and the first magnetic layer 51 and the second magnetic layer 52 are not connected to each other. An intermediate layer 53 made of a non-magnetic material such as magnetic ferrite is interposed, and a short ring 54 for passing a short-circuit current by a change in magnetic flux is embedded in the intermediate layer 53. The first magnetic body layer 51, the second magnetic body layer 52, and the intermediate layer 53 constitute a ferrite body 58, and terminal electrodes 59a and 59b are formed on the end surfaces of the ferrite body 58. Yes.

  In Patent Document 1, an intermediate layer 53 made of a non-magnetic material is interposed between the first magnetic material layer 51 and the second magnetic material layer 52, thereby preventing mutual diffusion between the magnetic material layers during firing. The resulting degradation region of the magnetic characteristics can be reduced as much as possible, and a multilayer inductor having the magnetic layers 51 and 52 retaining the desired inductor characteristics can be obtained.

  As another prior art, as shown in FIG. 4, crystallized glass is mainly used between a magnetic ceramic layer 62 in which a coil conductor 61 is embedded and a dielectric ceramic layer 64 in which a capacitor conductor 63 is embedded. A laminated LC component having an intermediate layer 65 interposed therebetween is also known (Patent Document 2).

  In Patent Document 2, an intermediate layer 65 containing crystallized glass as a main component is interposed between the magnetic ceramic layer 62 and the dielectric ceramic layer 64, so that the magnetic ceramic layer 62 and The dielectric ceramic layer 64 is prevented from interdiffusing.

Japanese Patent Laid-Open No. 9-7835 JP 2001-244140 A

  However, in Patent Document 1, the intermediate layer 53 is formed of a non-magnetic material, and the base material is different from that of the first and second magnetic layers 51 and 52. There is a problem that the bonding strength between the first magnetic layer 51 and the second magnetic layer 52 is weak.

  Also, in Patent Document 2, since the intermediate layer 65 is mainly composed of crystallized glass, the intermediate layer 65 is different from the magnetic ceramic layer 62 and the dielectric ceramic layer 64 in the base material, as in Patent Document 1, and therefore. When fired, there is a problem that the bonding strength between the intermediate layer 65 and the magnetic ceramic layer 62 and the dielectric ceramic layer 64 is weak.

  On the other hand, in order to eliminate the influence of mutual diffusion during firing, as shown in FIG. 5, for example, the first coil embedded in the first magnetic layer 71 and the second magnetic layer 72, respectively. A method is conceivable in which the distance t between the conductor 73 and the second conductor coil 74 is larger than the mutual diffusion distance m.

  However, even if the separation distance t between the first conductor coil 73 and the second conductor coil 74 is larger than the mutual diffusion distance m, the characteristics of the magnetic material deteriorate in the region of the mutual diffusion distance m. There is a possibility that magnetic characteristics cannot be obtained.

  The present invention has been made in view of such circumstances, and even when ceramic layers having different compositions are laminated, the interdiffusion area is reduced without sacrificing the bonding strength at the interface, and the flexibility of design is reduced. An object of the present invention is to provide a multilayer ceramic electronic component capable of improving the above.

  In order to achieve the above object, a multilayer ceramic electronic component according to the present invention is a multilayer ceramic electronic component in which an intermediate layer is interposed between ceramic layers having different compositions, wherein the intermediate layer is at least one of an oxide and a nitride. One of these is added to the ceramic material, and the oxide and nitride have a sintering temperature higher than the sintering temperature of the ceramic material.

  The ceramic material has the same composition as one ceramic layer in contact with the intermediate layer, or the ceramic material has a mixed composition of both ceramic layers in contact with the intermediate layer. It is said.

  Furthermore, the present invention is characterized in that, in the above multilayer ceramic electronic component, the ceramic layer is a magnetic layer, and the ceramic material contained in the intermediate layer is a magnetic material.

  According to the multilayer ceramic electronic component, the intermediate layer is formed by adding at least one of an oxide and a nitride to a ceramic material, and the oxide and the nitride are formed by sintering the ceramic material. Since the sintering temperature is higher than the temperature, the sinterability at the interface of the ceramic layer is inhibited by the intermediate layer at the time of firing, and the mutual diffusion that can occur between the ceramic layers can be effectively suppressed. As a result, the characteristic deterioration area is reduced, so that the characteristic acquisition area can be increased, and the design flexibility can be improved.

  Further, by setting the ceramic material to the same composition as one ceramic layer in contact with the intermediate layer or a mixed composition of both ceramic layers in contact with the intermediate layer, the intermediate layer has at least one ceramic layer as a mother layer. Accordingly, the bonding strength between the ceramic layer and the intermediate layer can be improved as compared with the case where the intermediate layer is formed of a nonmagnetic material such as nonmagnetic ferrite or crystallized glass.

  Also, by using the ceramic layer as a magnetic layer and the ceramic material contained in the intermediate layer as a magnetic material, a multilayer inductor such as a noise countermeasure component having desired magnetic characteristics can be easily obtained.

  Next, embodiments of the present invention will be described in detail.

  FIG. 1 is a sectional view schematically showing an embodiment of a multilayer inductor as a multilayer ceramic electronic component according to the present invention. The multilayer inductor includes a first magnetic layer 1 and a second magnetic layer. The intermediate layer 3 is interposed between the first and second magnetic layers 1 and 2 and the intermediate layer 3 to form a ferrite body 4. A first coil conductor 5 is embedded in the first magnetic layer 1, a second coil conductor 6 is embedded in the second magnetic layer 2, and both end surfaces of the ferrite element body 4 are further embedded. Are formed with terminal electrodes 7a and 7b. The lead portion 5a of the first coil conductor 5 is electrically connected to the terminal electrode 7b, and the lead portion 6a of the second coil conductor 6 is electrically connected to the terminal electrode 7a.

  The first magnetic layer 1 is formed of a low permeability material having an initial permeability of 200 or less, and the first magnetic layer 1 and the first coil conductor 5 form a high frequency inductance. The second magnetic layer 2 is formed of a high magnetic permeability material whose initial permeability is higher than that of the first magnetic layer, and the second magnetic layer 2 and the second coil conductor 6 are for low frequency use. Inductance is formed.

  That is, the first and second magnetic layers 1 and 2 are formed of the same composition system ferrite material (for example, Fe-Ni-Cu-Zn system ferrite material), and the composition ratio of the ferrite material is set. By adjusting the initial magnetic permeability, the first magnetic layer 1 having a low magnetic permeability and the second magnetic layer 2 having a high magnetic permeability are formed.

In addition, in the intermediate layer 3, any one of oxide and nitride is added to the magnetic material constituting one of the first magnetic layer 1 and the second magnetic layer 2. Such oxides and nitrides have a sintering temperature higher than the sintering temperature of the magnetic material. Here, as the oxide, for example, Al ₂ O ₃ , SiO ₂ , and MgO can be used, and as the nitride, for example, Si ₃ N ₄ , AlN can be used. As a result, the sintering property at the interface between the first and second magnetic layers 1 and 2 is inhibited during firing, and the mutual diffusion distance M can be prevented from increasing. In addition, it is possible to reduce the magnetic property deterioration region in the second magnetic layer 2.

  Next, a method for manufacturing the multilayer inductor will be described with reference to FIG.

First, a first ferrite material is prepared by blending ferrite raw materials such as Fe ₂ O ₃ , NiO, CuO, and ZnO so that the initial permeability has a low permeability of 200 or less. Next, the first ferrite material is kneaded with a binder, a plasticizer, a dispersant, a solvent, and the like, and magnetic sheets 8 to 13 having a predetermined film thickness are produced using a molding method such as a doctor blade method. Thereafter, a laser beam machine is used so that the magnetic sheets 9 to 13 can be electrically connected, and via holes are formed at predetermined positions of the magnetic sheets 9 to 13. Then, electrode patterns 9a to 12a are screen-printed on the magnetic sheets 9 to 12 using a conductive paste containing a conductive material such as Ag or Cu.

  Next, an appropriate number of magnetic sheets 8 on which no electrode patterns are formed, magnetic sheets 9 to 12 on which electrode patterns 9a to 12a are formed, and a magnetic sheet 13 on which only via holes are formed are laminated to form a first sheet. A first laminated body 14 to be one magnetic layer 1 is formed.

Further, a second ferrite material is prepared by blending ferrite raw materials such as Fe ₂ O ₃ , NiO, CuO, and ZnO so that the initial magnetic permeability is higher than that of the first magnetic layer. Next, the second ferrite material is kneaded with a binder, a plasticizer, a dispersant, a solvent, and the like, and magnetic sheets 15 to 19 having a predetermined thickness are produced using a doctor blade method or the like. Thereafter, a laser beam machine is used so that the magnetic sheets 15 to 18 can be electrically connected, and via holes are formed at predetermined positions of the magnetic sheets 15 to 17. And electrode patterns 16a-18a are screen-printed on the magnetic sheets 16-18 using the conductive paste containing conductive materials, such as Ag and Cu.

  Next, the magnetic sheet 15 having only via holes, the magnetic sheets 16 to 18 having the electrode patterns 16a to 18a, and the appropriate number of magnetic sheets 19 having no electrode patterns are stacked. The second laminated body 20 to be the second magnetic layer 2 is formed.

Next, a substance having a sintering temperature equal to or higher than the sintering temperature of the first or second ferrite material, specifically, an oxidation material is applied to the ferrite material of either the first ferrite material or the second ferrite material. A third ferrite material is manufactured by adding at least one of a material (for example, Al ₂ O ₃ , SiO ₂ , MgO) and a nitride (for example, Si ₃ N ₄ , AlN). Thereafter, an intermediate sheet 21 to be the intermediate layer 3 is produced in the same manner as described above, and a via hole 21a is formed in the intermediate sheet 21.

  The oxide and the nitride must be added to such an extent that the bonding property at the interface with the first and second magnetic layers 1 and 2 does not deteriorate and the sintering property does not deteriorate. From this viewpoint, it is preferable to add the oxide and the nitride so that the content in the intermediate sheet 21 is 1 to 2% by weight in total.

  Next, the first laminated body 14 and the second laminated body 20 are overlapped with each other via the intermediate sheet 21, and then pressed and fired at a predetermined temperature, whereby the ferrite element body 4 is formed.

  And the conductive paste which has Ag, Ag-Pd, etc. as a main component is apply | coated to the both ends of the ferrite element | base_body 4, and a baking process is performed, and a multilayer inductor is manufactured.

As described above, in this embodiment, the intermediate layer 3 has Al ₂ O ₃ , SiO ₂ having a sintering temperature higher than the sintering temperature of the magnetic material constituting the first and second magnetic layers 1 and _{2. 2} , at least one of oxides such as MgO and nitrides such as Si ₃ N ₄ and AlN is added to the magnetic material, so that the first and second magnetic layers 1, Since the sinterability at the interface between the intermediate layer 3 and the intermediate layer 3 is hindered, the interdiffusion distance M is suppressed, and as a result, the characteristic deterioration region can be reduced, so that the characteristic obtainable region can be increased. Flexibility can be improved.

  Moreover, since the base material has the same component composition as the ferrite material constituting the first magnetic layer 1 or the second magnetic layer 2, it differs from the case where crystallized glass or nonmagnetic ferrite is used for the intermediate layer. Also, the bondability at the interface is good.

  In addition, this invention is not limited to the said embodiment, The intermediate | middle layer 3 can also be laminated | stacked and laminated | stacked the arbitrary number of intermediate sheets 21. FIG. The number of laminated first and second magnetic layers 1 and 2 and the electrode pattern are not particularly limited as long as they form a coil pattern. Moreover, you may comprise the 1st magnetic body layer 1 and the 2nd magnetic body layer 2 with the ferrite material of a different composition type | system | group.

  Moreover, in the said embodiment, although the intermediate sheet 21 which comprises the intermediate | middle layer 3 is formed with the ferrite material of the same composition as any one of a 1st ferrite material or a 2nd ferrite material, It is also preferable to use a material composed of a mixed composition of a ferrite material and a second ferrite material.

  Further, in the above embodiment, the multilayer inductor is exemplified as the multilayer ceramic electronic component. However, the multilayer capacitor in which the dielectric ceramic layers having different compositions are laminated, and the multilayer LC component including the dielectric layer and the magnetic layer. It goes without saying that the same applies to the above.

  Next, examples of the present invention will be specifically described.

First ferrite material obtained by blending ferrite raw materials such as Fe ₂ O ₃ , NiO, CuO, ZnO so that the initial permeability is 5, is dispersed in water as a solvent and polyvinyl alcohol as a binder. A first magnetic material sheet (ceramic green sheet) having a thickness of 25 μm is prepared by a doctor blade method, and a plurality of first magnetic sheets are laminated so that the thickness after firing is 500 μm. The 1st laminated body was produced.

Further, a _second ferrite material obtained by preparing a ferrite material such as Fe ₂ O ₃ , NiO, CuO, ZnO so that the initial permeability is 800 is dispersed in water and polyvinyl alcohol to form a slurry, A second magnetic sheet (ceramic green sheet) having a thickness of 25 μm is prepared by a doctor blade method, and then a plurality of second magnetic sheets are stacked so that the thickness after firing is 500 μm. The body was made.

Next, Al is added to the ferrite raw material such as Fe ₂ O ₃ , NiO, CuO, and ZnO constituting the first magnetic sheet so that the content of Al ₂ O ₃ as an oxide is 2% by weight. ₂ O ₃ is added to prepare a third ferrite material, which is then dispersed in water and polyvinyl alcohol to form a slurry, an intermediate sheet is produced by the doctor blade method, and the intermediate thickness is set to 150 μm after firing. Sheets were laminated to produce an intermediate to be an intermediate layer.

  Next, the first laminated body and the second laminated body were superposed and bonded via an intermediate, and subjected to a firing treatment in air at 915 ° C., thereby producing the ferrite body of the example.

  In addition, as a comparative example, the first magnetic layer and the second magnetic layer were directly overlapped and pressure-bonded, and subjected to a firing treatment at 915 ° C. in air to produce a comparative ferrite body.

  Next, the ferrite bodies of the above examples and comparative examples were broken, the crystal state of the cross section was observed with a scanning electron microscope, and the mutual diffusion distance M (see FIG. 1) was calculated.

この表１から明らかなように比較例は、第１の磁性体層と第２の磁性体層とを直接重ね合わせているため、焼成温度付近で反応が進行して物質移動が活発になり、その結果相互拡散が進行し、相互拡散距離Ｍが２５０μｍと大きくなった。 Table 1 shows the mutual diffusion distance M of the examples and comparative examples.

As is clear from Table 1, in the comparative example, the first magnetic layer and the second magnetic layer are directly overlapped, so that the reaction proceeds near the firing temperature and the mass transfer becomes active. As a result, the interdiffusion progressed, and the interdiffusion distance M increased to 250 μm.

In contrast, in the example, the intermediate layer made of the third ferrite material in which Al ₂ O ₃ as an oxide having a sintering temperature higher than that of the first ferrite material is added to the first ferrite material. Is interposed between the first magnetic layer and the second magnetic layer, the intermediate layer inhibits the sintering at the interface and reduces the mobility of the substance, thereby reducing the interdiffusion distance. It has been found that M is suppressed to 150 μm, and as a result, the diffusion region becomes smaller and the degradation region of the magnetic characteristics can be reduced.

As the intermediate layer in the above embodiment, instead of the material obtained by adding _Al 2 _{O 3} (oxide) in a first ferrite _material, in place of the Al 2 _{O 3,} or in addition to _Al 2 _{O 3} Si Similar effects can be obtained when a nitride such as ₃ N ₄ or AlN is added to the first ferrite material.

It is sectional drawing which shows one Embodiment of the laminated coil component which concerns on this invention. It is a perspective view for demonstrating the manufacturing method of the said multilayer coil component. It is sectional drawing which shows an example of the conventional laminated coil component. It is sectional drawing which shows the other conventional example of laminated coil components. FIG. 3 is a cross-sectional view of the laminated coil component shown in [Problems to be solved by the invention].

Explanation of symbols

1 First magnetic layer (ceramic layer)
2 Second magnetic layer (ceramic layer)
3 middle class

Claims (4)

In a multilayer ceramic electronic component in which an intermediate layer is interposed between ceramic layers having different compositions,
The intermediate layer is formed by adding at least one of oxide and nitride to the ceramic material, and the oxide and nitride have a sintering temperature higher than the sintering temperature of the ceramic material. A multilayer ceramic electronic component characterized by that.   2. The multilayer ceramic electronic component according to claim 1, wherein the ceramic material has the same composition as one of the ceramic layers in contact with the intermediate layer.   2. The multilayer ceramic electronic component according to claim 1, wherein the ceramic material has a mixed composition of both ceramic layers in contact with the intermediate layer.   4. The multilayer ceramic electronic component according to claim 1, wherein the ceramic layer is a magnetic layer, and the ceramic material contained in the intermediate layer is a magnetic material. 5.

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