JP2010235324A - Ferrite composition, ferrite sintered body, composite lamination type electronic component, and method for manufacturing ferrite sintered body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ferrite composition firable at low temperature and also having high specific resistance and a high Q value. <P>SOLUTION: The ferrite composition contains iron oxide, zinc oxide, manganese oxide and nickel oxide, wherein the content of iron oxide is 45.0-50.0 mol% expressed in terms of Fe<SB>2</SB>O<SB>3</SB>, the content of zinc oxide is 15.5-30.0 mol% expressed in terms of ZnO, the content of manganese oxide is 0.1-4.0 mol% expressed in terms of Mn<SB>2</SB>O<SB>3</SB>, the content of nickel oxide is 14.0-39.4 mol% expressed in terms of NiO, the content of copper oxide is ≤2.0 mol% expressed in terms of CuO and the content of boron oxide is 0.1-2.0 mass% expressed in terms of B<SB>2</SB>O<SB>3</SB>per the content in total of the iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a ferrite composition, a ferrite sintered body, a composite multilayer electronic component, and a method for producing a ferrite sintered body.

  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 part having a capacitor and an inductor using Ni—Cu—Zn ferrite.

  Further, as an LC type composite part, an integrated type of an inductor using Ni—Cu—Zn ferrite and a varistor using ZnO has been studied. However, when such an inductor and varistor are integrated and sintered, the Cu component contained in the Ni—Cu—Zn-based ferrite constituting the inductor substrate diffuses and moves to the varistor side, and varistor characteristics (for example, frequency characteristics) Will deteriorate. In order to avoid such a phenomenon, a Zn-based ferrite having a reduced Cu content has been proposed.

Japanese Patent No. 2727509

  As described above, when the Cu content of the Zn-based ferrite is reduced, it is necessary to increase the firing temperature of the ferrite in order to improve the sintered density of the inductor base material. However, when the conductor portion of the inductor is formed of a metal material such as Ag or an Ag—Pd alloy, the conductor portion tends to deteriorate when the firing temperature is increased. Therefore, there is a demand for a ferrite that can reduce the Cu content and can be fired at a low temperature (for example, about 800 to 940 ° C.).

  On the other hand, ferrite having a high specific resistance is required as a base material for inductors. This is because if the specific resistance of the ferrite is small, problems may occur in the manufacturing process of the multilayer chip inductor. Further, as a base material for inductors, ferrite having a high Q value is required from the viewpoint of reducing the loss of composite parts.

  The present invention has been made in view of the above circumstances, and is capable of low-temperature firing, a ferrite composition having a high specific resistance and a high Q value, and a composite multilayer electron having an element body made of the ferrite composition An object of the present invention is to provide a component, and to provide a ferrite sintered body comprising such a ferrite composition and a method for producing the same.

The present invention is a ferrite composition containing iron oxide, zinc oxide, manganese oxide and nickel oxide, wherein the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide is 45.0～50.0Mol% content in terms _{of Fe} 2 _{O 3,} 15.5～30.0Mol% content of zinc oxide in terms of ZnO, the content of manganese oxide in _Mn 2 _{O 3} in terms of 0. 1 to 4.0 mol%, nickel oxide content is 14.0 to 39.4 mol% in terms of NiO, copper oxide content is 2.0 mol% or less in terms of CuO, and boron oxide content is B ₂ O _The ferrite composition which is 0.1 to 2.0% by mass in terms of ₃ is provided.

  Such a ferrite composition can be fired at a low temperature and has a high specific resistance and a high Q value. The reason why such an effect is obtained is, for example, the following factors. Since the ferrite composition of the present invention contains a predetermined amount of boron oxide together with iron oxide, zinc oxide and nickel oxide, a sintered body having a sufficiently high sintering density can be obtained by low-temperature firing. Further, since a predetermined amount of manganese oxide is contained in the main component including iron oxide, zinc oxide, and nickel oxide, it is possible to increase the specific resistance and the Q value. The reason why the effect is obtained is not limited to the above factors.

  Moreover, it is preferable that the ferrite composition of this invention contains 0.1-10 mass% of transition metal boron oxides. In this case, the transition metal boron oxide serves as a sintering aid and can be fired at a lower temperature.

  Moreover, this invention provides the ferrite sintered compact which consists of the said ferrite composition.

  Since the ferrite sintered body of the present invention is composed of the ferrite composition having the above characteristics, it can be fired at a low temperature and has a high specific resistance and a high Q value.

  The present invention also includes an inductor element body and an inductor element portion having an electrode disposed inside the inductor element body, a varistor element body and a varistor element section having an electrode disposed inside the varistor element body, And the inductor element body provides a composite multilayer electronic component made of the ferrite composition.

  In the composite multilayer electronic component of the present invention, since the inductor body is made of the ferrite composition having the above characteristics, it can be fired at a low temperature and has a high specific resistance and a high Q value. Further, since the content of copper oxide is sufficiently reduced, when the inductor element body is integrally fired with the varistor element body or the like, the diffusion of the Cu component to the varistor element body or the like is sufficiently reduced, and the varistor element The varistor characteristics in the portion can be maintained well.

In addition, the present invention relates to the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide, and the content of iron oxide is 45.0 to 50.0 mol% in terms of Fe ₂ O ₃ , oxidation. 15.5～30.0Mol% content of zinc calculated as ZnO, 0.1～4.0Mol% in the amount of manganese oxide is _Mn 2 _{O 3} in terms of the content of nickel oxide in terms of NiO 14.0 ～39.4Mol%, 2.0 mol% content of copper oxide in terms of CuO or less, and calcining the mixed material content of boron oxide is 0.1 to 2.0 mass% in terms _{of B} 2 _{O 3} Thus, there is provided a method for producing a ferrite sintered body having a calcining step for obtaining a calcined body and a firing step for firing the calcined body to obtain a ferrite sintered body.

  The method for producing a ferrite sintered body according to the present invention uses a mixed material containing a predetermined amount of boron oxide together with iron oxide, zinc oxide and nickel oxide, so that the sintered body has a sufficiently high sintered density by low-temperature firing. It can be. Further, since a predetermined amount of manganese oxide is contained in the main component containing iron oxide, zinc oxide and nickel oxide, it is possible to increase the specific resistance and the Q value. Moreover, since the manufacturing method of the ferrite sintered body of the present invention causes boron oxide to react with the mixed material in the calcination step, boron oxide is precipitated on the surface of the calcination body by moisture in the atmosphere until the firing step. Can be suppressed.

  According to the present invention, it is possible to provide a composite multilayer electronic component having a ferrite composition that can be fired at a low temperature and has a high specific resistance and a high Q value, and an element body made of the ferrite composition, and A ferrite sintered body comprising such a ferrite composition and a method for producing the same can be provided.

It is a perspective view which shows the ferrite sintered compact of one Embodiment of this invention. 1 is a perspective view showing a multilayer filter using a ferrite composition according to an embodiment of the present invention with a part thereof cut away. FIG. 3 is an exploded perspective view showing an element part of the multilayer filter shown in FIG. 2. It is a figure which shows the XRD pattern of the ferrite sintered compact of one Embodiment of this invention. It is an expanded sectional view showing typically the fine structure of the ferrite sintered compact of one embodiment of the present 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.

  The ferrite composition of this embodiment contains iron oxide, zinc oxide, manganese oxide, and nickel oxide as main components. Moreover, the ferrite composition of this embodiment may contain copper oxide as an optional component. Furthermore, the ferrite composition of the present embodiment contains boron oxide as an auxiliary component in addition to the main component. The main component and copper oxide of the ferrite composition form a ferrite phase that is the main phase (main crystal phase) of the ferrite composition.

The content of iron oxide is 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, and 45.5. It is preferably ˜50.0 mol%, more preferably 46.5 to 50.0 mol%, and still more preferably 47.0 to 50.0 mol%. When the content of iron oxide exceeds 50.0 mol%, the specific resistance of the sintered body decreases, and when it is less than 45.0 mol%, the sintered density of the sintered body decreases.

  Content of zinc oxide is 15.5-30.0 mol% in conversion of ZnO with respect to the sum total of content of iron oxide, zinc oxide, manganese oxide, nickel oxide, and copper oxide, and 20.0-30. It is preferably 0 mol%, more preferably 20.5 to 30.0 mol%, still more preferably 21.5 to 30.0 mol%. When the content of zinc oxide exceeds 30.0 mol%, the Q value of the sintered body decreases, and when it is less than 15.5 mol%, the sintered density of the sintered body decreases.

The content of manganese oxide is 0.1 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, It is preferable that it is -3.5 mol%, It is more preferable that it is 0.1-2.5 mol%, It is still more preferable that it is 0.1-2.0 mol%. When the content of manganese oxide exceeds 4.0 mol%, the sintered density of the sintered body decreases, and when it is less than 0.1 mol%, the specific resistance of the sintered body decreases.

  The content of nickel oxide is 14.0 to 39.4 mol% in terms of NiO with respect to the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide, and 16.0 to 38. 9 mol% is preferable, and 21.0 to 38.0 mol% is more preferable. When the content of nickel oxide exceeds 39.4 mol%, the sintered density of the sintered body decreases, and when it is less than 14.0 mol%, the Q value of the sintered body decreases.

  The ferrite composition of the present embodiment may not contain any copper oxide. When the ferrite composition contains copper oxide, the content of copper oxide exceeds 0 in terms of CuO with respect to the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide. It is the range of 0 mol% or less. The content of copper oxide is preferably 1.75 mol% or less in terms of CuO, and 1.25 mol% or less with respect to the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide. More preferably, it is more preferably 0.75 mol% or less. When the content of copper oxide exceeds 2.0 mol%, the ESD resistance is lowered, and the Cu component is diffused into a varistor laminated portion described later, thereby reducing the varistor characteristics.

The content of boron oxide is 0.1 to 2.0% by mass in terms of B ₂ O _{3 with} respect to the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide. It is preferably 1 to 1.5% by mass, more preferably 0.1 to 1.0% by mass, and still more preferably 0.1 to 0.75% by mass. When the content of boron oxide is less than 0.1% by mass, the sintered density of the sintered body decreases, and when it exceeds 2.0% by mass, the sintered density of the sintered body decreases.

The ferrite composition of the present embodiment preferably contains a transition metal boron oxide. Transition metal boron oxides tend to form a different phase (crystal phase different from the main phase) with respect to the main phase, and examples thereof include Ni—Fe—B—O-based compounds such as Ni ₂ FeBO ₅ . The presence of the transition metal boron oxide can be confirmed using X-ray diffraction.

  The content of the transition metal boron oxide is preferably 0.1 to 10% by mass, more preferably 1.0 to 10% by mass, and still more preferably 1.0 to 7.0% by mass with respect to the entire ferrite composition. . When the content of the transition metal boron oxide is less than 0.1% by mass, the sintered density of the sintered body tends to decrease, and when it exceeds 10% by mass, the sintered density of the sintered body decreases. Tend. The content of the transition metal boron oxide can be measured using a scanning transmission electron microscope (STEM).

  The total content of the main components of iron oxide, zinc oxide, manganese oxide and nickel oxide is 85% of the entire ferrite composition from the viewpoint of further improving the sintered density, specific resistance and Q value. It is preferably ˜99.9% by mass, more preferably 90 to 99% by mass, and still more preferably 90 to 95% by mass.

  The ferrite composition of this embodiment may be a composition in the form of unsintered powder, aggregates, or the like, or may be a solid content contained in the slurry. Since the ferrite composition of the present embodiment is excellent in sinterability, a ferrite sintered body having a sufficiently high sintered density (sintered body density) even when fired at a low temperature of about 800 to 940 ° C. can do. Therefore, for example, it can be suitably used as a magnetic layer of a multilayer chip inductor using Ag, which is required to be sintered at a low temperature, as a conductor.

  FIG. 1 is a perspective view showing a ferrite sintered body of the present embodiment. The ferrite sintered body 1 is made of the above ferrite composition.

The sintered density of the ferrite sintered body of the present embodiment, it is preferably, more preferably 5.05 g / cm ³ or more, 5.1 g / cm ³ or more and 5.0 g / cm ³ or more More preferably. When the sintered density is less than 5.0 g / cm ³ , the magnetic permeability tends to decrease significantly.

  The specific resistance (electric resistivity) of the sintered ferrite body of the present embodiment is preferably 0.1 MΩ · m or more, more preferably 0.5 MΩ · m or more, and 1.5 MΩ · m or more. More preferably it is. When the specific resistance is less than 0.1 MΩ · m, the plating tends to be elongated in the terminal electrode plating process which is a part of the manufacturing process of the multilayer chip inductor, and the characteristics of the multilayer chip inductor tend to be defective.

  Next, a preferred embodiment of the method for producing the ferrite sintered body will be described below.

  The method for producing the ferrite sintered body includes a preparation step of preparing an oxide mixed powder containing iron oxide, zinc oxide, manganese oxide, nickel oxide and boron oxide, and optionally containing copper oxide, and the above oxidation. A calcining step of calcining the product mixed powder to obtain a calcined body, and a calcining step of pulverizing and shaping the obtained calcined body and firing to obtain a ferrite sintered body.

In the preparation step, powders of iron oxide, zinc oxide, manganese oxide, nickel oxide, copper oxide as an optional component, and boron oxide are prepared. Iron oxide, zinc oxide, manganese oxide, the total content of nickel oxide and copper oxide, 45.0～50.0Mol% content of iron oxide calculated as _Fe 2 _{O 3,} the content of zinc oxide ZnO 15.5-30.0 mol% in terms of conversion, manganese oxide content 0.1-4.0 mol% in terms of Mn ₂ O ₃ , nickel oxide content 14.0-39.4 mol% in terms of NiO, Weigh so that the content of copper oxide is 2.0 mol% or less in terms of CuO and the content of boron oxide is 0.1 to 2.0% by mass in terms of B ₂ O ₃ , for example, mixed by a ball mill. An oxide mixed powder is prepared.

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 high specific resistance and a high Q value are combined.

  An organic vehicle containing an organic solvent and an organic binder may be mixed with the oxide mixed powder and mixed as a slurry. Thus, the mixed oxide powder can be uniformly mixed by mixing in a slurry state, that is, in a wet manner.

  In the calcination step, the oxide mixed powder obtained in the preparation step or the slurry containing the oxide calcination is calcined, for example, in an air atmosphere at 600 to 1000 ° C. for 1 to 20 hours. Thereafter, the calcined body is pulverized with a ball mill or the like to obtain a pulverized product. 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 obtained calcined body tends to aggregate and become difficult to pulverize.

  In the firing step, a pulverized product of the calcined body is formed to produce a formed body, and the formed body is fired to obtain a ferrite sintered body made of the ferrite composition. An additive such as an organic binder may be added to the pulverized product of the calcined body. The molded body can be produced by a general method such as press molding. Firing of the molded body can be performed under conditions of a firing temperature of 800 to 940 ° C. and a firing time of 1 to 10 hours. When the firing temperature is too low, or when the firing time is too short, a sintered body having a high sintered density tends to be difficult to obtain. On the other hand, when the firing temperature is too high, or when the firing time is too long, abnormal grain growth of the obtained ferrite sintered body occurs and the mechanical strength tends to be impaired.

  In the method for manufacturing a ferrite sintered body according to the present embodiment, boron oxide is mixed with iron oxide, zinc oxide, manganese oxide, nickel oxide, etc. in the preparation step, so that boron oxide and iron oxide or nickel oxide are mixed in the calcination step. Etc. tend to react to form transition metal boron oxide. Since this transition metal boron oxide is insoluble in solvents such as water, it suppresses the elution of boron oxide until the firing process compared to the case where boron oxide is added to the main component after the calcining process. Can do. Therefore, the change in the content of boron oxide in the firing step can be suppressed. Furthermore, it becomes possible for boron oxide to react uniformly with the main component in the calcination step, and the composition of the sintered body can be made more uniform.

The method for producing a ferrite sintered body of the present invention is not limited to the above embodiment. For example, you may manufacture a ferrite sintered compact by the method of adding a boron oxide after a calcination process as follows. That is, with respect to the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide, the content of iron oxide is 45.0 to 50.0 mol% in terms of Fe ₂ O ₃ , and the content of zinc oxide 14.0~39.4mol There 15.5～30.0Mol% in terms of ZnO, 0.1～4.0Mol% in the amount of manganese oxide is _Mn 2 _{O 3} in terms of the content of nickel oxide in terms of NiO %, A preparation step of preparing an oxide mixed powder having a copper oxide content of 2.0 mol% or less in terms of CuO, a calcining step of calcining the oxide mixed powder to obtain a calcined body, and obtaining was the calcined body was pulverized by a ball mill or the like, iron oxide, zinc oxide, manganese oxide, 0.1 to 2 boron oxide in terms _of B ₂ O ₃ with respect to the total content of the nickel oxide and copper oxide. Addition step of adding 0% by mass and boron oxide Molding the mixed powder obtained by mixing the pulverized product of the calcined body, and firing to obtain a ferrite sintered body by firing, it may be a production method having.

  The composition of the ferrite sintered body made of the ferrite composition thus obtained usually matches the usage ratio of each oxide used as a raw material. With the above-described method for producing a ferrite sintered body, a ferrite sintered body having a high sintering density can be obtained even if the firing temperature in the firing step is as low as about 800 to 940 ° C. Such a ferrite sintered body has a sufficiently high specific resistance and a high Q value. Therefore, it can be suitably used as a magnetic layer of an inductor. Further, since the ESD resistance of the varistor layer is hardly lowered, it is suitably used as an inductor element body of a composite part of an inductor and a varistor.

  Next, a preferred embodiment of a multilayer filter that is a composite part of an inductor produced using the above ferrite composition and a varistor will be described.

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

  The inductor multilayer portion 6 includes an inductor element body 10 formed by sequentially laminating a plurality of inductor layers 10 a to 10 i and a conductor pattern (electrode) 16 disposed inside the inductor element body 10. The varistor laminated portion 7 includes a varistor element body 11 formed by sequentially laminating a plurality of varistor layers 11 a to 11 d, and an 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 inductor layers 10a to 10i are made of the above-described ferrite sintered body. Since this ferrite sintered body has a sufficiently reduced copper oxide content than ordinary Zn-based ferrite, it sufficiently suppresses the diffusion of the Cu component from the inductor multilayer portion 6 to the varistor multilayer portion 7. Can do. Therefore, even if the above-mentioned ferrite sintered body is combined with the varistor, the varistor characteristics such as the ESD resistance can be sufficiently satisfactorily maintained.

  Conductor patterns 16a to 16h having desired shapes are formed on the inductor layers 10b to 10i, respectively. 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 excellent varistor characteristics and also has a high dielectric constant (ε). Further, when Al is further contained, the resistance becomes low. Moreover, other additives, for example, elements such as Cr, Ca, Si, and K may be contained as necessary.

  A substantially rectangular ground electrode 17 a electrically connected to the ground terminal electrode 5 is formed on the varistor layer 11 b of the varistor laminated portion 7. On the varistor layer 11c, a substantially rectangular hot electrode 17b electrically connected to the output terminal electrode 4 is formed. The ground electrode 17a and the hot electrode 17b are opposed to each other, and are partially overlapped with each other through the varistor layer 11b when viewed from the stacking direction, thereby exhibiting a varistor function.

  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, Ag, Ag-Pd, and alloys thereof can be preferably used.

The intermediate layer 8 is made of an insulating material having electrical insulation properties, for example, a sintered body mainly composed of ZnO and Fe ₂ O ₃ . By providing the intermediate laminated portion 9 made of such a material between the inductor laminated portion 6 and the varistor laminated portion 7, crosstalk between them can be suppressed, and as a result, the inductor laminated portion 6 becomes a varistor. The influence received from the multilayer part 7 and the influence that the varistor multilayer part 7 receives from the inductor multilayer part 6 can be reduced.

  The multilayer filter 100 having the above-described multilayer structure prevents a current that has flowed 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, a method for manufacturing the multilayer filter 100 described above will be described.

  In the same manner as the preparation step in the method for manufacturing a ferrite sintered body described above, a magnetic slurry containing an oxide mixed powder blended at a predetermined ratio is prepared. Then, a magnetic slurry is applied on a PET (polyethylene terephthalate) film by a doctor blade method or the like to form an inductor green sheet having a thickness of about 20 μm, for example.

  Subsequently, a through hole is formed at a desired position of the inductor 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, conductive patterns 16a to 16h are formed on the inductor green sheet by a screen printing method or the like. In addition, via conductors 26a to 26g are formed by filling a through hole formed in the inductor green sheet with a conductive paste. As the conductive paste used for printing the conductor patterns 16a to 16h and the via conductors 26a to 26g, a paste containing Ag or an Ag—Pd alloy powder as a main component can be used.

Subsequently, a varistor slurry is prepared by mixing a varistor raw material powder that becomes the varistor layers 11a to 11d after firing, and an organic vehicle containing an organic solvent and an organic binder. The form of the varistor raw material powder is not particularly limited as long as it becomes a varistor having a predetermined composition after being integrally fired. A mixed powder containing a predetermined amount of various metal compounds such as Bi ₂ O ₃ , Pr ₆ O ₁₁ , CoO, Cr ₂ O ₃ and Al ₂ O ₃ can be used as an additive to ZnO as a main component. Moreover, you may use the varistor powder which preliminarily calcined and ground the varistor ceramic of predetermined composition.

  Subsequently, a varistor slurry is applied on the PET film by a doctor blade method or the like to form, for example, a varistor green sheet having a thickness of about 30 μm.

  Subsequently, a ground electrode 17a and a hot electrode 17b are formed on the varistor green sheet by screen printing or the like using a conductive paste. As the conductive paste, a paste containing Ag or an Ag—Pd alloy powder as a main component can be used.

Further, an intermediate material green sheet to be the intermediate layer 8 is 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.

  Subsequently, an inductor green sheet in which no conductor part is formed, an inductor green sheet in which a conductor part of a predetermined shape is formed, an intermediate material green sheet, and a varistor green sheet in which a ground electrode 17a or a hot electrode 17b is formed, The varistor green sheets on which no electrodes are formed are sequentially laminated as shown in FIG. 3, pressed, and then cut into a predetermined shape to obtain a green laminate of the element body 2. Thereafter, the green laminate is baked under predetermined conditions (for example, 900 ° C. for 2 hours in the air), whereby the element body 2 is obtained. Since the element body 2 has almost no diffusion of the Cu component from the inductor multilayer portion 6 to the varistor multilayer portion 7 in the vicinity of the interface between the inductor multilayer portion 6 and the varistor multilayer portion 7, the varistor multilayer portion 7 has good varistor characteristics. can get.

  Subsequently, a conductive paste is applied to the end portion in the longitudinal direction of the element body 2 and the center of both side surfaces in the longitudinal direction, and heat treatment is performed under a predetermined condition (for example, 650 to 800 ° C. in the atmosphere) to burn the terminal electrode. As the conductive paste, a paste containing powder containing Ag as a main component can be used. Thereafter, the terminal electrode surface 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.

  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 may not have the intermediate multilayer part 9 and the inductor multilayer part 6 and the varistor multilayer part 7 may be directly joined. Also in this case, since the copper oxide content of the inductor body is sufficiently reduced, the diffusion of the Cu component from the inductor multilayer portion 6 to the varistor multilayer portion 7 is sufficiently suppressed. In FIG. 7, good varistor characteristics can be obtained.

  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 Examples 1 to 24)
As the raw material powder, commercially available Fe ₂ O ₃ powder, ZnO powder, Mn ₂ O ₃ powder, NiO powder and CuO powder were weighed so as to have the compositions shown in Tables 1 to 4. Further, _Fe 2 _{O 3} powder, ZnO powder, _Mn 2 _{O 3} powder, the total of NiO powder and CuO _powder, a B 2 _{O 3} powder were weighed so that a mass ratio shown in Table 1-4. In Production Examples 21 and 31, no B ₂ O ₃ powder was used. These raw material powders were wet mixed for 40 hours using a steel ball mill and then dried to obtain oxide mixed powders. The obtained oxide mixed powder was calcined at 720 ° C. for 10 hours. The obtained calcined body was mixed and ground in a steel ball mill for 40 hours to prepare a calcined powder.

Subsequently, the prepared calcined powder was granulated by adding an aqueous polyvinyl alcohol solution as a binder. The granules thus obtained are press-molded to form a compact having a molding density of 3.10 g / cm ³ (outer diameter: 12 mm, thickness 2 mm) and a toroidal shape (outer diameter 13 mm, inner diameter 6 mm, height 3 mm). ) Was produced.

  The compacts of Production Examples 1 to 24 were fired in the atmosphere at a firing temperature of 900 ° C. for 2 hours to obtain disk-shaped and toroidal-shaped ferrite sintered bodies made of the ferrite composition. As shown in Tables 1 to 4, each of the ferrite sintered bodies of Production Examples 1 to 24 contains a component having a predetermined composition.

<Evaluation of ferrite sintered density>
The ferrite sintered density was determined from the mass of each disk-shaped ferrite sintered body and the volume of the ferrite sintered body determined from the measured values of the outer diameter and thickness. The case where the sintered density was 5.0 g / cm ³ or more was judged to be good. The results were as shown in Tables 1-4.

<Evaluation of specific resistance>
The resistance R in the thickness direction of each disk-shaped ferrite sintered body was measured using a high resistance meter (trade name: R8340, manufactured by Advantest) with a measurement voltage set to 10V. Specific resistance ρ (ρ = R × circular partial area of sintered body / thickness of sintered body) was calculated from the measured value of resistance R. The case where the specific resistance was 0.1 MΩ · m or more was judged as good. The results were as shown in Tables 1-4.

<Evaluation of initial permeability (μi)>
After winding the wire around each toroidal ferrite sintered body 20 times, the initial permeability (μi) at 1 MHz was measured using an LCR meter (trade name: HP4285A, manufactured by Hewlett-Packard Company). The results were as shown in Tables 1-4.

<Evaluation of Q value>
After winding the wire around each toroidal ferrite sintered body 20 times, the Q value at 10 Hz of each sample was measured using an LCR meter (trade name: HP4285A, manufactured by Hewlett-Packard Company). The case where the Q value was 5 or more was judged to be good. The results were as shown in Tables 1-4.

<Evaluation of composition and microstructure>
The presence of transition metal boron oxide was confirmed using X-ray diffraction. In FIG. 4, the XRD pattern of the ferrite sintered compact of the manufacture example 12 is shown. Based on the peak indicated by “◯” in FIG. 4, it was confirmed that Ni ₂ FeBO ₅ was contained in the ferrite sintered body.

The content of the transition metal boron oxide was measured as follows. The ferrite sintered bodies of Production Examples 12, 21, 23 and 24 were observed with a scanning transmission electron microscope (STEM: manufactured by Hitachi High-Tech, trade name: HD-2000), and the attached energy dispersive X-ray spectrometer was used. Concentration analysis, and a main phase containing Ni—Zn (main crystal phase) present in the ferrite sintered body in the STEM image, and a different phase containing Ni ₂ FeBO ₅ (crystal phase different from the main phase), It was identified from the hole part.

  FIG. 5 is an enlarged cross-sectional view schematically showing the microstructure of the ferrite sintered body of Production Example 12. In FIG. 5, A to C represent a main phase, a different phase, and a hole portion, respectively.

Next, the area ratio of the main phase, the different phase, and the pore portion was calculated using an STEM image in which a fine structure as shown in FIG. 5 was copied. Then, assuming that the main phase, the heterogeneous phase, and the pore portion are similar, the volume ratio was calculated by raising the area ratio to 3/2. Furthermore, using the theoretical density of the ferrite sintered body estimated from the constituent elements (main phase: 5.30 g / cm ³ , different phase: 5.17 g / cm ³ ), the mass ratio of the different phase was calculated. Table 5 shows the calculated mass ratio of the different phases.

<ESD tolerance evaluation of varistor>
First, as raw material powder, commercially available Fe ₂ O ₃ powder, ZnO powder, Mn ₂ O ₃ powder, NiO powder and CuO powder are weighed to have the composition shown in Table 6, and Fe ₂ O ₃ powder, ZnO powder, B ₂ O ₃ powder was weighed so as to have a mass ratio shown in Table 6 with respect to the total of Mn ₂ O ₃ powder, NiO powder and CuO powder. These raw material powders and an organic vehicle were mixed to prepare a magnetic slurry.

  This magnetic slurry was applied on a PET film by a doctor blade method to produce an inductor green sheet having a thickness of 20 μm. Thereafter, a through hole is formed at a predetermined position on the inductor green sheet by a laser processing machine, and a conductive pattern having a predetermined shape and a via conductor in the through hole are formed by screen printing using a conductive paste mainly composed of Ag. Thus, an inductor green sheet having a conductor portion was formed.

Subsequently, a varistor raw material powder in which a predetermined amount of ZnO, Bi ₂ O ₃ , Pr ₆ O ₁₁ , CoO, Cr ₂ O ₃ and Al ₂ O ₃ was mixed with an organic vehicle was mixed 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, an electrode having a predetermined pattern was formed on the varistor green sheet by a screen printing method using a conductive paste containing Ag as a main component, thereby forming a varistor green sheet on which the electrodes were formed.

  Subsequently, an inductor green sheet without a conductor part, an inductor green sheet with a conductor part, a varistor green sheet with an electrode and a varistor sheet without an electrode are prepared, and the sequence shown in FIG. A green laminate for a multilayer filter was produced by laminating with This green laminate for a multilayer filter is cut into a rectangular parallelepiped having a length of 2.0 mm, a width of 1.2 mm, and a thickness of 1.0 mm after firing, and then fired in the atmosphere at 900 ° C. for 2 hours to obtain a multilayer type A filter element was produced. Thereafter, a conductive paste mainly composed of silver is applied to the end of the multilayer filter element body, and the terminal electrode is baked by baking at 650 to 800 ° C. in the atmosphere. Further, Ni / Sn (Ni , Sn) (in order of Sn). In this way, a sample (multilayer filter) for ESD tolerance test including the ferrite sintered body of Production Examples 25 to 30 was produced.

  Using the obtained sample, an ESD tolerance test was performed as follows. In the ESD tolerance test, measurement is performed based on an electrostatic discharge immunity test (level 4, contact discharge, test voltage: 8 kV, number of discharges: 10 times) defined in IEC (International Electrotechnical Commission) standard IEC61000-4-2. went. When the ESD tolerance was 8 kV or more, it was judged that the ESD tolerance was sufficient and judged as “A”, and when the ESD tolerance was less than 8 kV, judged as “B”. The reason why the criterion is 8 kV or more is that if it is 8 kV or more, the level 4 of IEC61000-4-2 is satisfied.

Further, the varistor voltage (V ₀ ) before the electrostatic discharge immunity test and the varistor voltage (V ₁ ) after the electrostatic discharge immunity test are measured, respectively, and the change width (ΔV ₁ mA (%) = (V ₁ −V ₀ ) / V ₀ × 100). The varistor voltage is measured using a source-measure unit (manufactured by KEITHLEY, model number: KEITHLEY2000). The voltage applied to the external terminal of the sample is gradually increased, and the voltage at the time when 1 mA of current flows through the sample is measured. The value was measured. The results of the ESD tolerance test are as shown in Table 6.

<Correlation between boron oxide addition and ferrite sintered density>
The disk-shaped ferrite sintered bodies of Production Examples 31 to 33 were produced as follows. The ferrite sintered body of Production Example 31 was produced in the same manner as in Production Example 21 except that the firing temperature in the firing step was 925 ° C. Ferrite sintered body of Production Example 32 is obtained by pulverizing the calcined body obtained by the calcining step with a ball mill or the like, and containing Fe ₂ O ₃ powder, ZnO powder, Mn ₂ O ₃ powder, NiO powder and CuO powder Manufactured in the same manner as in Production Example 31, except that a mixed powder obtained by adding and mixing boron oxide in an amount of 1.0% by mass in terms of B ₂ O ₃ was added to and mixed with the total amount, and the firing step was performed. did. In the ferrite sintered body of Production Example 33, boron oxide is added to the total content of Fe ₂ O ₃ powder, ZnO powder, Mn ₂ O ₃ powder, NiO powder and CuO powder in the preparation step before the calcination step. _It was produced in the same manner as in Production Example 31, except that 1.0% by mass in terms of ₂ O ₃ was added and mixed.

  Using the obtained ferrite sintered bodies of Production Examples 31 to 33, the correlation between the ferrite sintered density, the presence or absence of addition of boron oxide, and the addition procedure was evaluated. The ferrite sintered density was calculated from the mass and volume of the ferrite sintered body in the same manner as described above. The results were as shown in Table 7.

  From the results of Tables 1 to 7, the ferrite composition of the present invention can be fired at a low temperature, so that the sintered density can be sufficiently increased, and the specific resistance, magnetic permeability and Q value are high level values. I was able to. It was also confirmed that when combined with a varistor, the ESD resistance of the varistor can be maintained well.

  DESCRIPTION OF SYMBOLS 1 ... Ferrite sintered body, 6 ... Inductor laminated part (inductor element part), 7 ... Varistor laminated part (varistor element part), 9 ... Intermediate laminated part (joint intermediate body), 10 ... Inductor element body, 11 ... Varistor element Body, 16, 16a to 16h ... conductor pattern (electrode), 17, 17a, 17b ... electrode, 100 ... multilayer filter (composite multilayer electronic component).

Claims (5)

A ferrite composition containing iron oxide, zinc oxide, manganese oxide and nickel oxide,
For the total content of the iron oxide, the zinc oxide, the manganese oxide, the nickel oxide and the copper oxide,
45.0～50.0Mol% in the content of said iron oxide in terms _{of Fe} 2 _{O 3,}
The zinc oxide content is 15.5 to 30.0 mol% in terms of ZnO,
0.1～4.0Mol% in the content of the manganese oxide _Mn 2 _{O 3} in terms of,
The nickel oxide content is 14.0 to 39.4 mol% in terms of NiO,
Wherein 2.0 mol% content of copper oxide in terms of CuO or less, and ferrite composition content of boron oxide is 0.1 to 2.0 mass% in terms _{of B} 2 _{O 3.}   The ferrite composition according to claim 1, comprising 0.1 to 10% by mass of a transition metal boron oxide.   A ferrite sintered body comprising the ferrite composition according to claim 1 or 2. An inductor element body and an inductor element portion having an electrode disposed inside the inductor element body, and a varistor element body and a varistor element section having an electrode disposed inside the varistor element body are laminated,
A composite multilayer electronic component, wherein the inductor body is made of the ferrite composition according to claim 1. With respect to the total content of iron oxide, zinc oxide, manganese oxide, nickel oxide and copper oxide, the content of the iron oxide is 45.0 to 50.0 mol% in terms of Fe ₂ O ₃ , and the content of the zinc oxide 14.0 to 39 but 15.5～30.0Mol% in terms of ZnO, the 0.1～4.0Mol% in the amount of manganese oxide is _Mn 2 _{O 3} in terms of the content of the nickel oxide in terms of NiO .4Mol%, the 2.0 mol% content of copper oxide in terms of CuO or less, and the content of boron oxide is calcined mixed material is 0.1 to 2.0 mass% in terms _{of B} 2 _{O 3} A calcining step to obtain a calcined body,
And a firing step of firing the calcined body to obtain a ferrite sintered body.

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