JP5471672B2 - Multilayer electronic component and manufacturing method thereof - Google Patents

Description

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

  In a computer device, a multilayer varistor, an inductor (ferrite chip), a capacitor chip, and the like are incorporated in an input / output portion of a circuit board and a circuit in order to prevent noise generation and intrusion of noise from the outside.

  However, when components such as a multilayer varistor, an inductor, and a capacitor chip are provided on a circuit board, these components occupy a large area of the board, and a mounting space increases. In addition, the cost tends to increase due to an increase in the number of parts.

  In order to deal with such problems, a composite component is manufactured by integrally sintering each element chip while being bonded to each other, and installed on a circuit board, thereby reducing the number of components and making the component compact. Attempts have been made to reduce space (see, for example, Patent Document 1). Patent Document 1 proposes an LC-type composite component having a capacitor and an inductor using a ferrite sintered body.

Japanese Patent No. 2727509

  By the way, the ferrite sintered body used for the inductor body of the multilayer inductor or the LC type composite component as described above has an element deterioration due to diffusion of electrode components or diffusion of different elements between elements of different materials. In order to prevent this, it is required to sinter at a low temperature. In order to reduce the sintering temperature of the ferrite sintered body, a sintering aid such as boron oxide is used. However, when the ferrite and the electrode containing Ag (silver) are simultaneously fired and formed, such as a laminated part, the sinterability of the ferrite may be greatly deteriorated.

  The inventors of the present invention have studied the cause of the problem. When silver or a silver alloy is used as an electrode material, Ag diffused from the electrode is caused to flow out of the sintered body with a sintering aid. Thus, it was found that this hinders the promotion of sintering.

  The present invention has been made in view of the above circumstances, and includes an inductor element body that has a high density and sufficiently suppresses deterioration of the inductor element body even if the main component of the internal electrode in the inductor element portion is Ag. An object is to provide a multilayer electronic component. Further, it is possible to manufacture a multilayer electronic component having a high-density inductor element even when the firing temperature is lowered, and the multilayer electronic component having an inductor element in which deterioration during firing is sufficiently suppressed can be produced. An object is to provide a manufacturing method.

  The present invention relates to a multilayer electronic component including an inductor element portion having an inductor element body and a plurality of internal electrodes arranged inside the inductor element body, wherein the Ag content in the internal electrode is 85% by mass or more. And the inductor body is composed of a ferrite sintered body containing a ferrite composition and a boron oxide, and the Ag content of the ferrite sintered body between adjacent internal electrodes is 0.18% by mass or less. Provide parts.

  In the multilayer electronic component of the present invention, since the inductor element is composed of a ferrite sintered body containing boron oxide, the sintering proceeds sufficiently even when the firing temperature is lowered to a range of 800 to 940 ° C., for example. . Therefore, the inductor body has a high density. Further, as described above, since sintering can be performed at a low firing temperature, the resistance of the internal electrode can be sufficiently reduced by using Ag as the main component of the internal electrode. Further, since the Ag content in the ferrite sintered body between the internal electrodes is sufficiently reduced, the deterioration of the inductor body is sufficiently suppressed. As described above, since the deterioration of the inductor body is suppressed and the density is high, the Q value of the inductor body can be increased.

In the multilayer electronic component of the present invention, the content of boron oxide in the ferrite sintered body is preferably 0.1 to ₂ % by mass in terms of B ₂ O ₃ . As a result, the density of the inductor body can be further improved.

  The present invention also provides a lamination process for forming a laminate in which a green sheet for an inductor containing a ferrite composition and a boron oxide and a conductor portion containing Ag are alternately laminated, and the laminate has an oxygen concentration of 5 volumes. And firing in an atmosphere of less than or equal to% to obtain an inductor element portion having an inductor element made of a ferrite sintered body and an internal electrode containing Ag disposed inside the inductor element. A method of manufacturing a multilayer electronic component including an inductor element portion is provided.

  In the method for manufacturing a multilayer electronic component of the present invention, a multilayer body including a green sheet containing boron oxide is fired in an atmosphere having an oxygen concentration of 5% by volume or less. By firing in an atmosphere having a reduced oxygen concentration in this way, diffusion of Ag from the conductor portion into the green sheet during firing can be suppressed. Thereby, the outflow of the boron oxide from the green sheet and the ferrite sintered body due to the diffusion of Ag can be suppressed. Therefore, even if the firing temperature in the firing step is lowered, an inductor body made of a ferrite sintered body having a sufficiently high density can be formed. In addition, the deterioration of the inductor body due to the diffusion of Ag can also be suppressed. As described above, since the deterioration of the inductor body is suppressed and the density is high, the Q value of the inductor body can be increased.

  Moreover, in the manufacturing method of the multilayer electronic component of this invention, it is preferable that Ag content rate in an internal electrode is 85 mass% or more. In the method for manufacturing a multilayer electronic component according to the present invention, it is possible to suppress the diffusion of Ag into the inductor element body, so that the content ratio of Ag in the internal electrode is increased while suppressing the deterioration of the inductor element body. Thus, the electrical resistance of the internal electrode can be reduced.

  Moreover, in the manufacturing method of the multilayer electronic component of this invention, it is preferable that Ag content rate of the ferrite sintered compact between adjacent internal electrodes is 0.18 mass% or less. As a result, the Q value of the inductor element portion can be increased.

  Further, the method for manufacturing a multilayer electronic component according to the present invention includes calcining a raw material containing boron oxide before the lamination step to prepare a calcined body containing boron oxide and a ferrite composition. It is preferable to have a process and a sheet forming process for producing a green sheet including a calcined body. Thereby, in a sintering process, it can suppress further that a boron oxide flows out outside from a green sheet or a ferrite sintered compact. Therefore, it is possible to form an inductor element portion including a ferrite sintered body having a higher density.

Further, it is preferable that the content of boron oxide in the calcined body is 0.1 to 2 mass% in terms of B ₂ O _3. Thereby, even if the firing temperature is further lowered, it is possible to form an inductor element portion including a ferrite sintered body having a high density.

  According to the present invention, it is possible to provide a multilayer electronic component including an inductor element body that has a high density and sufficiently suppresses deterioration of the inductor element body even if the main component of the internal electrode in the inductor element portion is Ag. Can do. Further, it is possible to manufacture a multilayer electronic component having a high-density inductor element even when the firing temperature is lowered, and the multilayer electronic component having an inductor element in which deterioration during firing is sufficiently suppressed can be produced. A manufacturing method can be provided.

1 is a perspective view of a multilayer filter that is a preferred embodiment of a multilayer electronic component according to the present invention, with a part thereof cut away. FIG. 2 is an exploded perspective view of a multilayer body portion of the multilayer filter shown in FIG. 1. It is an expanded sectional view showing typically an example of the fine structure of the ferrite sintered compact which constitutes the inductor element with which the multilayer electronic component of the present invention is equipped. It is explanatory drawing for demonstrating the measuring method of the composition of the ferrite sintered compact between the internal electrodes in the inductor element part of the multilayer electronic component of this invention.

  In the following, preferred embodiments of the present invention will be described with reference to the drawings as the case may be. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate descriptions are omitted.

  FIG. 1 is a perspective view in which a part of a composite multilayer electronic component which is an embodiment of the multilayer electronic component of the present invention is cut away. The composite multilayer electronic component shown in FIG. 1 is a multilayer filter. FIG. 2 is an exploded perspective view showing a multilayer body portion of the multilayer filter shown in FIG. The multilayer filter (composite multilayer electronic component) 100 includes a multilayer body 2, an input terminal electrode 3 and an output terminal electrode 4, and a pair of ground terminal electrodes 5. The multilayer body 2 includes an inductor element section (inductor multilayer section) 6, a varistor element section (varistor multilayer section) 7, and an intermediate multilayer section (junction intermediate body) interposed between the inductor element section 6 and the varistor element section 7. 9. The input terminal electrode 3 and the output terminal electrode 4 are disposed at both ends in the longitudinal direction of the multilayer body 2. The pair of ground terminal electrodes 5 are respectively disposed on both side surfaces in the longitudinal direction of the multilayer body 2.

  As shown in FIG. 2, the inductor element section 6 includes an inductor element body 10 formed by sequentially laminating a plurality of inductor layers 10 a to 10 i, and a first inner electrode 16 disposed inside the inductor element body 10. Have The varistor element section 7 includes a varistor element body 11 formed by sequentially laminating a plurality of varistor layers 11 a to 11 d, and a second internal electrode 17 disposed inside the varistor element body 11. The intermediate laminated part 9 is formed by laminating a plurality of intermediate layers 8.

  The first internal electrode 16 contains Ag. From the viewpoint of further reducing the electrical resistance of the first internal electrode 16, the Ag content in the first internal electrode 16 is preferably 88% by mass or more, and more preferably 90% by mass or more. The first internal electrode 16 may contain, for example, Pd or Cu as a metal component other than Ag. Note that the above Ag content is the mass ratio of the silver element contained in the first internal electrode 16 based on the entire first internal electrode 16.

  The inductor layers 10a to 10i are made of a ferrite sintered body. The ferrite sintered body preferably contains a NiZn-based or NiCuZn-based ferrite composition as a main component, more preferably a NiZn-based ferrite composition. By using a ferrite sintered body containing a NiZn-based ferrite composition as a main component, the Cu content in the ferrite sintered body is reduced, and diffusion of the Cu component from the inductor element portion 6 to the varistor element portion 7 is reduced. It can be sufficiently suppressed. Thereby, varistor characteristics such as ESD tolerance can be made sufficiently excellent.

The ferrite sintered body contains boron oxide in addition to the ferrite composition. The boron oxide includes boron oxide such as B ₂ O ₃ and transition metal boron oxide such as Ni—Fe—B—O system. The content of boron oxide in the ferrite sintered body is preferably 0.1 to ₂ % by mass, more preferably 0.1 to ₂ % by mass, when the total boron element (B) contained in the ferrite sintered body is converted to B ₂ O _3. Is 0.2 to 1.3% by mass. The density of a ferrite sintered compact can be made still higher by making the content rate of the boron oxide in a ferrite sintered compact into the above-mentioned range.

Transition metal boron oxide tends to form a different phase (a crystal phase different from the main phase) with respect to the main phase (the crystal phase of ferrite). Specific examples of the transition metal boron oxide include Ni—Fe—B—O-based compounds such as Ni ₂ FeBO ₅ . The transition metal boron oxide can be identified and quantified using a scanning transmission electron microscope (STEM) or X-ray diffraction.

  FIG. 3 is an enlarged cross-sectional view schematically showing the fine structure of the ferrite sintered body constituting the inductor body 10 provided in the multilayer filter 100 of the present embodiment. The ferrite sintered body of FIG. 3 contains a ferrite composition as a main crystal phase A (main phase), and a boron oxide (for example, Ni—Fe—B—) as a crystal phase B (different phase) different from the main phase. O-based oxide). Further, the ferrite sintered body has pores C in addition to the main phase and the different phase.

  The ferrite composition contained as a main component in the ferrite sintered body contains, for example, iron oxide, zinc oxide and nickel oxide as essential components, and contains copper oxide and manganese oxide as optional components.

The content of iron oxide in the ferrite sintered body is preferably 45.0 to 50.0 mol in terms of Fe ₂ O _{3 with} respect to the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide. %, More preferably 45.5 to 50.0 mol%. When the content of iron oxide exceeds 50.0 mol%, the specific resistance of the ferrite sintered body tends to decrease. On the other hand, when the content of iron oxide is less than 45.0 mol%, the density of the ferrite sintered body tends to decrease.

  The content of zinc oxide in the ferrite sintered body is preferably 15.5 to 30.0 mol% in terms of ZnO with respect to the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide. More preferably, it is 18.0-30.0 mol%, More preferably, it is 20.0-28.0 mol%. When the content of zinc oxide exceeds 30.0 mol%, the Q value of the ferrite sintered body tends to decrease. On the other hand, if the zinc oxide content is less than 15.5 mol%, it may be necessary to increase the firing temperature.

  The content of nickel oxide in the ferrite sintered body is preferably 14 to 39 mol% in terms of NiO, and more preferably, with respect to the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide. It is 16-35 mol%, More preferably, it is 18-30 mol%. If the content of nickel oxide exceeds 39 mol%, it may be necessary to increase the firing temperature. On the other hand, when the content of nickel oxide is less than 14.0 mol%, the Q value of the ferrite sintered body tends to decrease.

The ferrite sintered body of the present embodiment may not contain copper oxide and / or manganese oxide at all. The content of manganese oxide in the ferrite sintered body is preferably 0 to 4.0 mol% in terms of Mn ₂ O _{3 with} respect to the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide. More preferably, it is 0-3.5 mol%, More preferably, it is 0.1-2.5 mol%. If the manganese oxide content exceeds 4.0 mol%, it may be necessary to increase the firing temperature.

  The content ratio of copper oxide in the ferrite sintered body is preferably 0 to 15.0 mol% in terms of CuO with respect to the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide. Preferably it is 0-11 mol%. When the content of copper oxide exceeds 15 mol%, the electrical resistance tends to decrease.

  The ferrite sintered body may contain a small amount of metal components as impurities in addition to the above components. However, from the viewpoint of obtaining the multilayer filter 100 having excellent inductor characteristics, it is preferable that the content of the metal component contained as an impurity in the ferrite sintered body is small. In particular, Ag has the effect of degrading the inductor characteristics and causing the boron oxide to flow out of the ferrite sintered body by combining with the boron oxide during firing of the ferrite sintered body.

  Therefore, from the viewpoint of forming the multilayer filter 100 including the inductor body 10 having excellent inductor characteristics, it is preferable that the content of Ag present in the form of silver or silver compound in the ferrite sintered body is low. Specifically, the Ag content of the ferrite sintered body between the two first internal electrodes 16 adjacent to each other is 0.18% by mass or less, preferably 0.15% by mass or less. When a conductive material containing Ag is used as the material of the first internal electrode 16, the portion between the first internal electrodes 16 adjacent to each other among the ferrite sintered bodies constituting the inductor body 10. The content of Ag in the ferrite sintered body is the highest. The portion between the first internal electrodes 16 has a great influence on the inductor characteristics of the inductor body 10, and thus the multilayer filter 100 having excellent inductor characteristics is obtained by reducing the Ag content in this portion. be able to. In addition, Ag content rate of a ferrite sintered compact is a mass ratio when the total of all silver components, such as silver and a silver compound contained in the said ferrite sintered compact, are converted into a silver element on the basis of a ferrite sintered compact. It is.

The density of the ferrite sintered body is preferably 4.8 g / cm ³ or more, more preferably 4.9 g / cm ³ or more, and further preferably 5.0 g / cm ³ or more. When the density is less than 4.8 g / cm ³ , the magnetic permeability tends to decrease.

  Conductor patterns 16a to 16h having desired shapes are formed on the inductor layers 10b to 10i in FIG. Specifically, substantially C-shaped conductor patterns 16c, 16e, and 16g corresponding to approximately 3/4 turns of the coil are formed on the inductor layers 10d, 10f, and 10h, respectively. Are formed with substantially U-shaped conductor patterns 16b, 16d and 16f corresponding to approximately 3/4 turns of the coil. Conductor patterns (leading electrodes) 16a and 16h connected to the input terminal electrode 3 and the output terminal electrode 4 are formed on the inductor layers 10b and 10i. Furthermore, via conductors 26a to 26g are formed, which respectively penetrate the inductor layers 10b to 10h and electrically connect the conductor patterns in contact with the inductor layers 10b to 10h. As a result, a spiral coil (conductor portion) of approximately 4.5 turns in which the conductor patterns (leading electrodes) 16a and 16h, the conductor patterns 16b to 16g, and the via conductors 26a to 26g are electrically connected is formed. Is done.

  The varistor layers 11a to 11d are made of, for example, a ceramic material mainly composed of ZnO. This ceramic material may contain Pr, Bi, Co, Al or the like as an additive component. When Co is contained in addition to Pr, it has both excellent varistor characteristics and a high dielectric constant (ε). Further, when Al is further contained, the resistance becomes low. Other additives, for example, elements such as Cr, Ca, Si, and K may be included as necessary.

  On the varistor layer 11 b of the varistor element portion 7, a substantially rectangular ground electrode 17 a electrically connected to the ground terminal electrode 5 is formed. On the varistor layer 11c, a substantially rectangular hot electrode 17b electrically connected to the output terminal electrode 4 is formed. The ground electrode (internal electrode) 17a and the hot electrode (internal electrode) 17b are opposed to each other, and partially overlap with each other through the varistor layer 11b when viewed from the stacking direction so that the varistor function is exhibited. ing.

  As the conductive material used for the ground electrode 17a and the hot electrode 17b, a metal material that can be fired simultaneously with the ceramic material forming the varistor layers 11a to 11d is used. That is, since the firing temperature of the varistor ceramic is usually about 800 to 940 ° C., a metal material that does not melt at that temperature is used. For example, a silver alloy such as silver or a silver-palladium alloy can be preferably used.

The intermediate layer 8 is made of an insulating material having electrical insulation properties, for example, a sintered body containing ZnO and Fe ₂ O ₃ as main components. By providing the intermediate laminated part 9 made of such an insulating material between the inductor element part 6 and the varistor element part 7, crosstalk between them can be suppressed. As a result, the influence which the inductor element part 6 receives from the varistor element part 7 and the influence which the varistor element part 7 receives from the inductor element part 6 can be relieved.

  The multilayer filter 100 having the above-described multilayer structure prevents a current that has flown suddenly due to the varistor effect from passing as noise when high-voltage noise exceeding the varistor voltage is applied to the input side. Can do.

Next, an example of a method for manufacturing the multilayer filter 100 will be described. The manufacturing method of the multilayer filter 100 includes the following steps.
(1) A calcining step of preparing a calcined body containing boron oxide and a ferrite composition by calcining an oxide mixed raw material containing boron oxide, and obtaining a magnetic material slurry by slurrying the calcined body (2) Inductor green sheet (first green sheet) is produced using magnetic slurry, and a varistor green sheet (second green sheet) is produced using varistor slurry. A conductor portion forming step of disposing a conductor portion containing Ag on the first green sheet and the second green sheet;
(4) Laminating step of forming a laminated body by laminating a plurality of first green sheets and a plurality of second green sheets on which conductor portions are arranged. (5) The laminated body has an oxygen concentration of 5% by volume or less. Baking process in a certain atmosphere

  Details of each step will be described below. In the calcining step, a magnetic slurry containing boron oxide and a ferrite composition is prepared by the following procedure. First, iron oxide, zinc oxide, manganese oxide, nickel oxide, and boron oxide powders are prepared. Based on the composition of the preferred ferrite sintered body described above, the powder to be used is selected, and the blending ratio of each powder is determined.

The content of boron oxide is preferably 0.1 to 2.0 mass in terms of B ₂ O ₃ with respect to the total of the raw materials (iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide) of the ferrite composition. %, More preferably 0.2 to 1.3% by mass.

The weighed ferrite composition raw material and boron oxide are mixed by, for example, a ball mill to prepare an oxide mixed powder. As the boron oxide source, boron-based glass containing boron oxide may be used instead of boron oxide powder. As the boron-based glass, commercially available glass can be used. The boron-based glass usually contains SiO ₂ , ZnO or the like in addition to B ₂ O ₃ . Even when boron-based glass is used as the boron oxide source, low-temperature firing is possible, and a ferrite sintered body having both a high specific resistance and a high Q value can be obtained.

  The prepared oxide mixed powder is calcined, for example, in an air atmosphere at 600 to 1000 ° C. for 1 to 20 hours to obtain a calcined body. The calcined body contains a ferrite composition as a main component and a boron oxide as a subcomponent. The obtained calcined body is pulverized using a ball mill or the like to obtain a calcined powder. When the calcination temperature is too low, or when the calcination time is too short, the uniformity of the obtained ferrite sintered body tends to be impaired. On the other hand, when the calcining temperature is too high, or when the calcining time is too long, the calcined body tends to aggregate and become difficult to pulverize.

  Next, the calcined powder can be mixed with an organic vehicle containing an organic solvent and an organic binder to obtain a magnetic slurry.

  In the sheet forming step, a green sheet for inductor (first green sheet) and a green sheet for varistor (second green sheet) are respectively produced using the magnetic substance slurry and the varistor slurry.

The varistor slurry can be prepared by mixing a varistor raw material powder and an organic vehicle containing an organic solvent and an organic binder. As the varistor raw material powder, conventionally used raw material powder can be used. For example, a mixed powder containing ZnO as a main component and Bi ₂ O ₃ , Pr ₆ O ₁₁ , CoO, Cr ₂ O _3, Al ₂ O _{3 and the} like as a subcomponent can be used. Further, as the varistor raw material powder, a powder obtained by pre-calcining and pulverizing a varistor ceramic having a predetermined composition may be used.

  The magnetic material slurry and the varistor slurry are respectively applied onto a PET (polyethylene terephthalate) film by a doctor blade method or the like, and for example, a first green sheet and a second green sheet having a thickness of about 20 to 30 μm are produced.

Further, an intermediate material green sheet to be the intermediate layer 8 may be prepared. The intermediate material green sheet is formed, for example, by applying a slurry using a mixed powder mainly composed of ZnO and Fe ₂ O ₃ as a raw material on a film by a doctor blade method. In addition, the number of intermediate material green sheets to be stacked is appropriately adjusted so that the thickness of the intermediate stacked portion 9 after firing is sufficient.

  In the conductor portion forming step, a conductor portion (conductor pattern, via conductor) containing Ag is disposed on the first green sheet and the second green sheet by the following procedure. First, a through hole is formed at a desired position of the manufactured first green sheet, that is, a position where via conductors 26a to 26g as described above are to be formed. The through hole can be formed by a laser processing machine or the like.

  Subsequently, a conductive paste is applied on the first green sheet by a screen printing method or the like to form conductor patterns 16a to 16h. In addition, via conductors 26a to 26g are formed by filling the through holes formed in the first green sheet with a conductive paste. The conductive paste used for printing the conductor patterns 16a to 16h and the via conductors 26a to 26g contains Ag. As the conductive paste, a paste having a composition in which, when fired to form the first internal electrode, the Ag content is preferably 85% by mass or more, more preferably 88% by mass or more. Specifically, what contains Ag powder and Ag-Pd alloy powder as a main component is mentioned. By increasing the Ag content of the first internal electrode 16 in this way, the electrical resistance of the first internal electrode 16 can be sufficiently reduced.

  Also on the second green sheet, the ground electrode 17a and the hot electrode 17b are formed using a conductive paste by a screen printing method or the like. The conductive paste may have the same composition as that applied on the first green sheet, or may have a different composition.

  In the laminating process, a plurality of first green sheets on which conductor portions are arranged, a plurality of second green sheets, and intermediate green sheets as necessary are respectively laminated, and a green laminate is formed by the following procedure. . First, a first green sheet in which no conductor part is formed, a first green sheet in which a conductor part (conductor pattern and via conductor) having a predetermined shape is formed, an intermediate material green sheet, and a conductor part 17a or conductor The second green sheet on which the portion 17b is formed and the second green sheet on which no electrode is formed are stacked and stacked as shown in FIG.

  The laminated body is pressed and cut into a predetermined shape to obtain a green laminated body of the multilayer body 2. Thereafter, the green laminate is fired in an atmosphere having an oxygen concentration of 5% by volume or less under conditions of a firing temperature of 800 to 940 ° C. and a firing time of 2 hours. As a result, the inductor element body 6 made of a ferrite sintered body and the inductor element portion 6 having the first internal electrode 16 containing Ag disposed inside the inductor element body 10, the varistor element body 11 and the varistor element body. 11 to obtain a multilayer body 2 in which the varistor element portion 7 having the second internal electrode 17 disposed inside the multilayer body 11 is laminated.

  Since the multilayer body 2 is fired in an atmosphere in which the oxygen concentration is reduced to 5% by volume or less, the diffusion of Ag from the conductor portion containing Ag into the first green sheet is sufficiently suppressed. can do. For this reason, it becomes possible to suppress the outflow of boron oxide contained in the first green sheet accompanying the diffusion of Ag to the outside. Therefore, even if the firing temperature is lower than before, the density of the ferrite sintered body can be sufficiently increased.

  Subsequently, a conductive paste is applied to the end portion in the longitudinal direction of the multilayer body 2 and the center of both side surfaces in the longitudinal direction, and heat treatment is performed under predetermined conditions (for example, 650 to 800 ° C. in the atmosphere) to thereby form the terminal electrodes 3. 4 is baked. As the conductive paste, a paste containing powder containing Ag as a main component can be used. Thereafter, the surface of the terminal electrode is plated to obtain the multilayer filter 100 in which the input terminal electrode 3, the output terminal electrode 4, and the ground terminal electrode 5 are formed. The plating is preferably electrolytic plating, and for example, Ni / Sn, Cu / Ni / Sn, Ni / Pd / Au, Ni / Pd / Ag, Ni / Ag, or the like can be used.

  In the manufacturing method described above, the amount of Ag diffused from the conductor portion (first internal electrode 16) during the firing step to the first green sheet (ferrite sintered body constituting the inductor body 10) is reduced. Therefore, the Ag content of the ferrite sintered body disposed between the conductor portions, that is, the first internal electrodes 16 can be sufficiently reduced. The Ag content of the ferrite sintered body between the first internal electrodes 16 adjacent to each other is preferably 0.18% by mass or less, and more preferably 0.15% by mass or less. Thus, although the electroconductive material containing Ag is used as the material of the conductor portion, the Ag content in the ferrite sintered body can be reduced.

  According to the manufacturing method described above, the ferrite sintered body has a sufficiently high inductor characteristic because it has a high density and a reduced Ag content. That is, according to the manufacturing method described above, the inductor element portion 6 is provided which has the first internal electrode 16 having a sufficiently low electric resistance and the ferrite sintered body (inductor body 10) having excellent inductor characteristics. The multilayer filter 100 to be formed can be formed.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, the multilayer filter 100 does not have the intermediate multilayer portion 9, and the inductor element portion 6 and the varistor element portion 7 may be directly joined. Further, in the above embodiment, the description has been given by taking the composite multilayer electronic component having the inductor element portion and the varistor element portion. However, the multilayer electronic component of the present invention is not limited to the composite type, and the inductor element portion. A multilayer inductor made of may be used.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

[Production of multilayer filter]
Example 1
As raw material powder, commercially available Fe ₂ O ₃ powder, ZnO powder, Mn ₂ O ₃ powder, NiO powder and B ₂ O ₃ powder were prepared. Then, _Fe 2 _{O 3} powder, ZnO powder, _Mn 2 _{O 3} powder and NiO powder were weighed so that the following proportions.

Fe ₂ O ₃ : 47.5 mol%
NiO: 26.0 mol%
ZnO: 25.0 mol%
Mn ₂ O ₃ : 1.5 mol%

0.5% by mass of B ₂ O ₃ powder was added to the total amount of each raw material powder weighed, and each raw material powder and B ₂ O ₃ powder were mixed to obtain an oxide mixed raw material. This oxide mixed raw material was calcined at 720 ° C. for 10 hours to obtain a calcined body. The obtained calcined body was mixed and ground for 40 hours using a steel ball mill to prepare a calcined powder. This calcined powder and an organic vehicle were mixed to prepare a magnetic slurry.

  This magnetic material slurry was applied onto a PET film by a doctor blade method to produce an inductor green sheet having a thickness of 20 μm. A through hole was formed at a predetermined position on the inductor green sheet by a laser processing machine, and a conductive paste was filled into the through hole to form a via conductor. A conductor pattern having a predetermined shape was formed on the inductor green sheet by screen printing. Thus, an inductor green sheet in which a conductor portion composed of a conductor pattern and a via conductor was formed was produced. Note that the conductive paste used here contains only silver as a metal component.

Separate from the inductor green sheet, a varistor green sheet was formed by the following procedure. First, commercially available ZnO powder, Bi ₂ O ₃ powder, Pr ₆ O ₁₁ powder, CoO powder, Cr ₂ O ₃ powder and Al ₂ O ₃ powder were prepared as raw material powders. A predetermined amount of this raw material powder was weighed and mixed with an organic vehicle to prepare a varistor slurry.

  This varistor slurry was applied onto a PET film by a doctor blade method to produce a varistor green sheet having a thickness of 30 μm. Thereafter, a conductive pattern was formed on the varistor green sheet by screen printing using a conductive paste containing Ag and optionally Pd. Further, the conductive paste was filled in the through hole to form a via conductor. Thus, a varistor green sheet in which a conductor portion composed of a conductor pattern and a via conductor was formed.

  The inductor green sheet and varistor green sheet produced as described above, and the inductor green sheet and varistor green sheet on which no conductor portion was formed were laminated in the order shown in FIG. 2 to produce a green laminate. The green laminate was cut into a predetermined size and then fired in an atmosphere having an oxygen concentration shown in Table 1 at a firing temperature of 896 ° C. for 2 hours to obtain a laminate body.

  Then, the conductive paste which has silver as a main component was apply | coated to the edge part of a laminated body, and it baked at 650-800 degreeC in air | atmosphere, and baked the terminal electrode. And the terminal electrode was electroplated with Ni / Sn (in order of Ni and Sn). As a result, the inductor element unit has an inductor element portion having a first internal electrode disposed inside the inductor body, and the second internal electrode disposed inside the varistor element body. A multilayer filter in which the varistor element part was laminated was obtained.

[Composition analysis of sintered ferrite]
The Ag content in the ferrite sintered body disposed between the first internal electrodes of the inductor element portion was measured by the following procedure. FIG. 4 is an explanatory view showing an enlarged part of the inductor element portion in order to explain a method for preparing a sample for composition analysis. The surface 10A of the inductor body (ferrite sintered body) 10 in the inductor element section 6 of the multilayer filter shown in FIG. 4A is formed on the first internal electrode 16A and the first surface using water-resistant abrasive paper (# 1500). Polishing was performed until the inductor body (ferrite sintered body) between the inner electrode 16B and the inner electrode 16B was exposed. FIG. 4B is an explanatory diagram schematically showing a sample after polishing. As shown in FIG. 4B, polishing was performed from the nearest first internal electrode 16B until the thickness of the ferrite sintered body became 10 μm.

  Then, Ag content rate was measured in the area | region 30 in the grinding | polishing surface 10B of a ferrite sintered compact using the laser ablation ICP mass spectrometer (LA-ICP-MS). LUV266X (trade name, manufactured by New Wave Research) was used for the laser part of the apparatus, and Agilent 7500 (trade name, manufactured by Agilent Technologies) was used for the PCP-MS part. The laser conditions were a spot diameter of 20 μm (diameter of the region 30 in FIG. 4B), an oscillation frequency of 10 Hz, and an output of 35%, and analysis was performed by a raster scan method.

Apart from the above-described analysis of the Ag content, the cut surface of the ferrite sintered body is analyzed by X-ray diffraction, and a scanning transmission electron microscope (STEM: manufactured by Hitachi High-Tech, trade name: HD-2000) is used. And observed. From the result of X-ray diffraction, it was confirmed that Ni ₂ FeBO ₅ was formed in the ferrite sintered body.

In addition, using an energy dispersive X-ray spectrometer attached to the scanning transmission electron microscope, element concentration analysis was performed on the cut surface of the ferrite sintered body. From these results, the ferrite sintered body contains a main phase (main crystal phase) containing NiZn ferrite, a different phase containing Ni ₂ FeBO ₅ (crystal phase different from the main phase), and vacancies. confirmed.

[Composition of the first internal electrode]
The content ratios of Ag and Pd in the first internal electrode 16 disposed inside the inductor element body 10 were calculated from the mass ratios of Ag and Pd with respect to the entire metal component contained in the metal paste used for forming the conductor portion. . The results are shown in Table 1.

[Measurement of density of sintered ferrite]
A ferrite sintered body having the same Ag content as that measured by laser ablation ICP mass spectrometry of the above-mentioned ferrite sintered body was separately prepared. The firing conditions were the same as when the multilayer filter was produced. From the mass and volume of the ferrite sintered body, the density of the ferrite sintered body was calculated. The results were as shown in Table 1.

[Measurement of Q value of inductor]
Using an LCR meter (trade name: HP4285A, manufactured by Hewlett-Packard Company), the Q value of the inductor of the multilayer filter at 10 MHz was measured. The results were as shown in Table 1.

[Measurement of electrical resistivity of internal electrode]
Using a source meter (manufactured by Keithley, trade name: 2400), the DC resistance of the first internal electrode in the inductor element portion of the multilayer filter was measured, and the electrical resistivity was calculated. The results were as shown in Table 1.

(Examples 2 to 3, Reference Example 4 )
Except that the composition of the conductive paste for forming the conductor part on the inductor green sheet was changed so that the first internal electrode of the inductor element part had the composition shown in Table 1, the same as in Example 1 A multilayer filter of Example 2 was produced. In the same manner as in Example 1, the Q value of the inductor, the electrical resistivity of the first internal electrode, the composition analysis of the ferrite sintered body in the inductor element portion, and the density measurement were performed. The results were as shown in Table 1.

(Example 5, Reference Example 8)
A multilayer filter of Example 5 and Reference Example 8 was produced in the same manner as in Example 1 except that the oxygen concentration in the atmosphere during firing (firing atmosphere) was as shown in Table 1. In the same manner as in Example 1, the Q value of the inductor, the electrical resistivity of the first internal electrode, the composition analysis of the ferrite sintered body in the inductor element portion, and the density measurement were performed. The results were as shown in Table 1.

(Example 6, Example 7)
Except that the composition of the conductive paste for forming the conductor part on the inductor green sheet was changed so that the first internal electrode of the inductor element part had the composition shown in Table 1, the same as in Example 5 The multilayer filters of Examples 6 and 7 were produced. In the same manner as in Example 1, the Q value of the inductor, the electrical resistivity of the first internal electrode, the composition analysis of the ferrite sintered body in the inductor element portion, and the density measurement were performed. The results were as shown in Table 1.

( Reference Example 9, Reference Example 10)
Except for changing the composition of the conductive paste for forming the conductor on the inductor green sheet so that the first internal electrode of the inductor element has the composition shown in Table 1, the same as in Reference Example 8 The laminated filters of Reference Examples 9 and 10 were produced. In the same manner as in Example 1, the Q value of the inductor, the electrical resistivity of the first internal electrode, the composition analysis of the ferrite sintered body in the inductor element portion, and the density measurement were performed. The results were as shown in Table 1.

(Comparative Example 1)
A multilayer filter of Comparative Example 1 was produced in the same manner as in Reference Example 4 except that the oxygen concentration in the atmosphere (firing atmosphere) during firing was as shown in Table 1. In the same manner as in Example 1, the Q value of the inductor, the electrical resistivity of the first internal electrode, the composition analysis of the ferrite sintered body in the inductor element portion, and the density measurement were performed. The results were as shown in Table 1.

  From the results in Table 1, it was confirmed that the multilayer filter of each example had a ferrite sintered body with a high density, and the sintering proceeded sufficiently even when the firing temperature was lowered. In addition, it was confirmed that the multilayer filter of each Example had a first internal electrode having a low electrical resistivity (0.85 μΩm or less) and a high Q value (5 or more). Even when the content of Ag in the first internal electrode of each example is increased, the diffusion of Ag into the ferrite sintered body is sufficiently suppressed, which contributes to the improvement of the density and the Q value. it is conceivable that.

  On the other hand, in Comparative Example 1 in which the oxygen concentration in the firing atmosphere was 21% by volume, the diffusion of Ag from the first internal electrode to the ferrite sintered body even when the Ag content of the first internal electrode was 85% by mass. It was confirmed that the Ag content in the ferrite sintered body was high. Along with the diffusion of Ag, boron oxide in the inductor green sheet flows out of the inductor green sheet, and thus the density of the ferrite sintered body cannot be increased.

(Examples 11 to 13)
As raw material powder, commercially available Fe ₂ O ₃ powder, ZnO powder, CuO powder, NiO powder and B ₂ O ₃ powder were prepared. Then, _Fe 2 _{O 3} powder, ZnO powder, CuO powder and NiO powder were weighed so that the following proportions.

Fe ₂ O ₃ : 48.8 mol%
NiO: 20.0 mol%
ZnO: 20.3 mol%
CuO: 10.8 mol%

The total of each raw material powder was weighed, B ₂ O ₃ powder was added 0.2 wt%, to obtain an oxide mixed raw material by mixing the raw material powder and B ₂ O ₃ powder. This oxide mixed raw material was calcined at 720 ° C. for 10 hours to obtain a calcined body. The obtained calcined body was mixed and ground for 40 hours using a steel ball mill to prepare a calcined powder. This calcined powder and an organic vehicle were mixed to prepare a magnetic slurry.

  The magnetic substance slurry was used, the oxygen concentration in the firing atmosphere was as shown in Table 2, or the first internal electrode having the composition shown in Table 2 was formed in the inductor element portion by changing the composition of the conductive paste. The multilayer filters of Examples 11 to 13 were produced in the same manner as Example 1 except that it was formed. In the same manner as in Example 1, the Q value of the inductor, the electrical resistivity of the first internal electrode, the composition analysis of the ferrite sintered body in the inductor element portion, and the density measurement were performed. The results were as shown in Table 2.

  From the results shown in Table 2, it was confirmed that when NiCuZn ferrite was used, the density of the ferrite sintered body was sufficiently high as in the case where NiZn ferrite was used. In addition, it was confirmed that the multilayer filter of each example had a first internal electrode with a low electrical resistivity and a high Q value (5 or more).

(Examples 14 to 16, Comparative Example 2)
1.0% by mass of B ₂ O ₃ powder is added to the total amount of each raw material powder weighed in the same manner as in Example 1, and each raw material powder and B ₂ O ₃ powder are mixed to obtain an oxide mixed raw material. It was. This oxide mixed raw material was calcined at 720 ° C. for 10 hours to obtain a calcined body. The obtained calcined body was mixed and ground for 40 hours using a steel ball mill to prepare a calcined powder. This calcined powder and an organic vehicle were mixed to prepare a magnetic slurry.

  The magnetic substance slurry was used, the oxygen concentration in the firing atmosphere was as shown in Table 3, or the first internal electrode having the composition shown in Table 3 was formed in the inductor element section by changing the composition of the conductive paste. Except for the formation, multilayer filters of Examples 14 to 16 and Comparative Example 2 were produced in the same manner as Example 1. In the same manner as in Example 1, the Q value of the inductor, the electrical resistivity of the first internal electrode, the composition analysis of the ferrite sintered body in the inductor element portion, and the density measurement were performed. The results are shown in Table 3.

  From the results shown in Table 3, it was confirmed that the density of the ferrite sintered body was sufficiently high as in Table 1. In addition, it was confirmed that the multilayer filter of each Example had a first internal electrode having a low electrical resistivity (0.85 μΩm or less) and a high Q value (5 or more).

( Reference Examples 17 to 19, Comparative Example 3)
A calcined powder was prepared in the same manner as in Example 1. To this calcined powder, 3.0 mass% of B ₂ O ₃ powder was added based on the calcined powder to prepare an oxide mixed raw material containing the calcined powder and B ₂ O ₃ powder. This oxide mixed raw material and an organic vehicle were mixed to prepare a magnetic slurry.

The magnetic substance slurry was used, the oxygen concentration in the firing atmosphere was as shown in Table 4, or the first internal electrode having the composition shown in Table 4 was formed in the inductor element portion by changing the composition of the conductive paste. Except for the formation, multilayer filters of Reference Examples 17 to 19 and Comparative Example 3 were produced in the same manner as in Example 1. In the same manner as in Example 1, the Q value of the inductor, the electrical resistivity of the first internal electrode, the composition analysis of the ferrite sintered body in the inductor element portion, and the density measurement were performed. The results were as shown in Table 4.

  From the results shown in Table 4, it was confirmed that the density of the ferrite sintered body was sufficiently high as in Table 1. Moreover, it was confirmed that the multilayer filter of each Example had a high Q value while having the first internal electrode having a low electrical resistivity.

  ADVANTAGE OF THE INVENTION According to this invention, a multilayer electronic component provided with the inductor element | base_body which is high density and the deterioration of the inductor element | base_body was fully suppressed can be provided. Further, it is possible to manufacture a multilayer electronic component having a high-density inductor element even when the firing temperature is lowered, and the multilayer electronic component having an inductor element in which deterioration during firing is sufficiently suppressed can be produced. A manufacturing method can be provided.

DESCRIPTION OF SYMBOLS 2 ... Laminated body, 3 ... Input terminal electrode (terminal electrode), 4 ... Output terminal electrode (terminal electrode), 5 ... Ground terminal electrode, 6 ... Inductor element part, 7 ... Varistor element part, 8 ... Intermediate layer, 9 ... intermediate laminated part, 10 ... inductor body, 16 ... first internal electrode, 17 ... second internal electrode, 17a ... ground electrode (conductor part), 17b ... hot electrode (conductor part), 30 ... region, 100 ... Multilayer filter.

Claims (5)

A multilayer electronic component comprising an inductor element having an inductor body and a plurality of internal electrodes arranged inside the inductor body,
The content of Ag in the internal electrode is 90% by mass or more,
The inductor element is made of a ferrite sintered body containing the ferrite composition of the NiZn based or NiCuZn-based, and a boron oxide containing a transition metal boron oxide,
A multilayer electronic component having an Ag content of 0.1% by mass or less between the adjacent internal electrodes. The multilayer electronic component according to claim 1, wherein the content of the boron oxide in the ferrite sintered body is 0.1 to ₂ % by mass in terms of B ₂ O ₃ . A lamination step of forming a laminate in which a green sheet for an inductor containing a ferrite composition and a boron oxide and a conductor portion containing Ag are alternately laminated;
An inductor element having an inductor element body made of a sintered ferrite body and an internal electrode containing Ag disposed inside the inductor element body by firing the laminate in an atmosphere having an oxygen concentration of 5% by volume or less. A firing step to obtain a part,
Wherein is the content of Ag in the internal electrodes 90 mass% or more, e Bei the inductor device portion content of Ag of the ferrite sintered body between is less than 0.1 wt% of adjacent said inner electrode ,
A method of manufacturing a multilayer electronic component, wherein the inductor element body includes a ferrite sintered body containing a NiZn-based or NiCuZn-based ferrite composition and a boron oxide containing a transition metal boron oxide . Before the laminating step,
Calcination of a raw material containing boron oxide to prepare a calcined body containing the boron oxide and the ferrite composition;
The manufacturing method of the multilayer electronic component of Claim 3 which has a sheet | seat formation process which produces the said green sheet containing the said calcined body. The method for manufacturing a multilayer electronic component according to claim 4, wherein the content of the boron oxide in the calcined body is 0.1 to ₂ % by mass in terms of B ₂ O ₃ .

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