JP2014189485A - Ferrite calcinated powder, laminate type coil part, method of producing ferrite calcinated powder and method of producing laminate type coil part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate type coil part which is reduced in stress strain and provides a high impedance and a ferrite calcinated powder which has a small density after calcination and provides a high magnetic permeability.SOLUTION: Instead of converting NiO contained in a powder before calcination entirely into a spinel structure by calcination, a part of NiO is left as NiO after calcination. More specifically, taking the amount of NiO not converted into the spinel structure in 1 pt. wt. of the ferrite calcinated powder as NS and the total amount of NiO in 1 pt. wt. of the ferrite calcinated powder as Wn, the ratio Rns of the NiO not converted into the spinel structure, represented by NS/Wn, is 0.49 or higher.

Description

  The present invention relates to a ferrite calcined powder, a laminated coil component produced using the ferrite calcined powder, a method for producing a ferrite calcined powder, and a method for producing a laminated coil component.

  As shown in FIG. 2, the multilayer coil component 10 includes a magnetic body portion 11 and a coil-shaped inner conductor portion 12 provided inside the magnetic body portion 11. The outer shape of the magnetic part 11 is a substantially rectangular parallelepiped. External electrodes 13 are provided at both ends of the magnetic body portion 11 in the longitudinal direction. The external electrode 13 is electrically connected to the internal conductor portion 12 drawn out at both ends in the longitudinal direction of the magnetic body portion 11. When the multilayer coil component 10 is used to absorb noise in a frequency range of 1 MHz to 1 GHz, for example, it is desirable that the multilayer coil component 10 can obtain a large impedance in this frequency domain.

  In general, the laminated coil component 10 includes a magnetic body portion 11 including a magnetic material such as ferrite and an inner conductor portion 12 including a conductive material. The magnetic body portion 11 and the inner conductor portion 12 have a linear expansion coefficient. Different. Therefore, in the cooling process after firing, which is one of the manufacturing processes of the multilayer coil component 10, stress distortion may occur in the magnetic body part 11 around the internal conductor part 12. In addition, the stress distortion described above may be further increased by heating or cooling the multilayer coil component 10 or applying external stress during reflow processing when the multilayer coil component 10 is mounted on a circuit board. There is also. Thereby, the impedance obtained from the multilayer coil component 10 is lowered. In order to solve the problem that the impedance is lowered, it is effective to reduce the stress strain caused to the magnetic body portion 11 of the multilayer coil component 10.

  A means for reducing this stress strain is disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-38904. Patent Document 1 includes a ceramic laminate in which a plurality of ceramic layers and a plurality of internal electrodes are stacked, the plurality of ceramic layers including voids, and voids of the ceramic layer disposed in the outermost layer of the ceramic laminate. A multilayer coil component having a structure in which the porosity is smaller than the porosity of the remaining ceramic layers is described. Here, the small porosity of the ceramic layer means that the ratio of the magnetic material per unit volume is large and the density of the magnetic part is large, and the high porosity of the ceramic layer means that the unit volume This means that the ratio of the magnetic material is small and the density of the magnetic part is small.

  Therefore, the multilayer coil component described in Prior Literature 1 has a structure in which the density of the magnetic body portion around the inner conductor portion is small and the density of the outer magnetic body portion away from the inner conductor portion is large. . If the density of the magnetic part around the inner conductor part is small, the internal stress generated in the magnetic part can be absorbed, and the stress distortion can be reduced. For this reason, the impedance obtained from the multilayer coil component is unlikely to decrease.

JP 2005-38904 A

  However, in the multilayer coil component described in the prior art document 1, since there are many holes in the magnetic body portion around the inner conductor portion, the ratio of the magnetic material per unit volume is small. Therefore, the density of the magnetic body portion is reduced, and the magnetic permeability in the magnetic body portion is reduced. That is, the multilayer coil component described in the prior art document 1 has a problem that although the impedance is not lowered due to stress strain, the original impedance is reduced.

  An object of the present invention is to provide a laminated coil component capable of reducing stress strain and obtaining a large impedance, and a manufacturing method thereof.

  Another object of the present invention relates to a material for a magnetic part of a multilayer coil component, and a ferrite calcined powder capable of obtaining a high magnetic permeability despite a low density after firing. And a method of manufacturing the same.

  The calcined ferrite powder according to the first aspect of the present invention contains at least Fe, Ni, and Zn as elements, and Ni is present as NiO constituting a part of the spinel structure, and changes into a spinel structure. The amount of NiO that is not changed to a spinel structure in 1 part by weight of the ferrite calcined powder is NS, and the total amount of NiO in 1 part by weight of the ferrite calcined powder is Wn. The ratio Rns of NiO that has not changed to the spinel structure represented by NS / Wn is 0.49 or more.

  A laminated coil component according to a second aspect of the present invention includes a magnetic body portion including a magnetic material, and a coil-shaped inner conductor portion provided inside the magnetic body portion, and includes a magnetic body. The part is formed by firing the calcined ferrite powder according to the first aspect of the present invention.

The method for producing a calcined ferrite powder according to the third aspect of the present invention is a method for producing the calcined ferrite powder according to the first aspect of the present invention, and includes at least Fe ₂ O ₃ , NiO and ZnO. And a calcination step of calcination of the mixture at a temperature rising rate of 100 ° C./min to 1000 ° C./min.

  The manufacturing method of the laminated coil component which concerns on the 4th aspect of this invention is slurry preparation which produces a magnetic body slurry by mixing resin with the ferrite calcining powder produced by the 3rd aspect of this invention. A sheet forming step for forming a green sheet by forming a magnetic material slurry into a sheet, a coil pattern forming step for forming a coil pattern on the green sheet, and a plurality of green sheets on which the coil pattern is formed are stacked And a laminate forming step for forming the laminate and a firing step for firing the laminate.

  In the first aspect of the present invention, the ratio Rns of NiO that has not changed to the spinel structure in the calcined ferrite powder is 0.49 or more. By using this calcined ferrite powder, a magnetic component having a low density and a high magnetic permeability can be obtained, as will be clarified by examples described later.

  In the second aspect of the present invention, the magnetic body portion of the multilayer coil component is configured using the calcined ferrite powder according to the first aspect as a material. According to this, it is possible to reduce the stress strain and obtain a multilayer coil component having a large impedance.

  In the third aspect of the present invention, the rate of temperature increase when producing the calcined ferrite powder is set to 100 ° C./min or more and 1000 ° C./min or less. By using the calcined ferrite powder produced by this production method, a magnetic component having a low density and a high magnetic permeability can be obtained, as will be clarified by examples described later.

  In the fourth aspect of the present invention, the magnetic body portion of the multilayer coil component is manufactured using the calcined ferrite powder manufactured according to the third aspect. According to this, it is possible to reduce the stress strain and obtain a multilayer coil component having a large impedance.

1A is an X-ray diffraction pattern of the calcined ferrite powder according to the comparative example, and FIG. 1B is an X-ray diffraction pattern of the calcined ferrite powder according to the present invention. 1 is a perspective view showing a general structure of a laminated coil component 10. It is explanatory drawing which showed how to obtain | require the ratio Rns of non-spinel type NiO. It is a conceptual diagram for demonstrating the sintering process and shrinkage | contraction rate of a ferrite calcining powder.

  As described above, the multilayer coil component 10 illustrated in FIG. 2 includes the magnetic body portion 11 containing a magnetic material and the coil-shaped inner conductor portion 12 provided inside the magnetic body portion 11. The outer shape of the magnetic part 11 is a substantially rectangular parallelepiped. External electrodes 13 are provided at both ends of the magnetic body portion 11 in the longitudinal direction. The external electrode 13 is electrically connected to the internal conductor portion 12 drawn out at both ends in the longitudinal direction of the magnetic body portion 11.

  In order to obtain a large impedance as the multilayer coil component 10, it is effective to increase the magnetic permeability of the magnetic body portion 11, and it is effective to reduce the density of the magnetic body portion 11 to reduce the stress strain. It is. Accordingly, in order to obtain a desired large value of impedance, it is important what kind of properties the magnetic body portion 11 is made.

In general, the magnetic part 11 is formed by firing a calcined ferrite powder. The ferrite calcined powder is produced by calcining a powdery mixture containing Fe ₂ O ₃ , NiO, and ZnO. During the calcination, most of the NiO in the calcined ferrite powder has a spinel structure (in this embodiment, the composition formula of the crystal structure is (Ni, Zn) O.Fe ₂ O ₃ ). Change.

  At this time, the inventors do not change all of the NiO in the mixture into a spinel structure during calcination, but intentionally leave NiO that has not changed to a spinel structure at a certain rate. A ferrite calcined powder was prepared. And by using this ferrite calcined powder, a magnetic component (ferrite bead) having a low density after firing and a high magnetic permeability was produced. In addition, by using this calcined ferrite powder, a multilayer coil component 10 capable of reducing stress strain and obtaining a large impedance was produced.

  The ferrite calcined powder according to the present embodiment includes at least Fe, Ni, and Zn as elements. Ni is present as NiO constituting a part of the spinel structure, and NiO that is not changed into the spinel structure. The ratio Rns (see Formula 1) of NiO that is present and has not changed to a spinel structure is 0.49 or more. Thereby, the magnetic component and the laminated coil component 10 as described above can be reliably manufactured.

Rns = NS / Wn (Formula 1)
S: The amount of NiO constituting part of the spinel structure in 1 part by weight of the ferrite calcined powder (NiO equivalent)
NS: amount of NiO not changed to a spinel structure in 1 part by weight of the calcined ferrite powder Wn: total amount of NiO in 1 part by weight of the calcined ferrite powder (S + NS)
Hereinafter, in Example 1, the ferrite calcined powder and the manufacturing method thereof will be described, and the process of deriving Rns in Equation 1 will be shown. In Example 2, the laminated coil component 10 and the manufacturing method thereof will be described.

(Ferrite calcined powder and manufacturing method thereof)
The calcined ferrite powder contains at least Fe, Ni, and Zn. Here, Fe, Ni, and Zn represent Fe, Ni, and Zn as elements, and may include Fe compounds, Ni compounds, and Zn compounds.

In Example 1, first, Fe ₂ O ₃ , CuO, NiO, and ZnO powders were prepared, Fe ₂ O ₃ : 48.0 mol% (65.05 wt%), CuO: 8.25 mol% (5 .57 wt%), NiO: 14.75 mol% (9.35 wt%), and ZnO: 29.0 mol% (20.03 wt%). In addition, the numerical value in a parenthesis is a value when a ratio is shown by weight%. The powder produced by blending is made into 100 parts by weight of the main component, and on the other hand, SnO ₂ is 0.60 part by weight, 12% by weight SiO ₂ -60% by weight ZnO-28% by weight B ₂ O ₃ glass powder Was added to make 0.30 parts by weight, respectively, to prepare a powdery mixture.

  This mixture was put into a ball mill together with pure water and PSZ (partially stabilized zirconia) balls, and mixed and ground for 48 hours. After removing PSZ balls and moisture from the pulverized product obtained by mixing and pulverizing, the mixture was heated to 700 ° C. under the temperature increase rate conditions shown in Table 1. And the same temperature was hold | maintained over about 10 minutes, and calcination was complete | finished. Thereby, the ferrite calcined powder shown to material number 1-6 was produced. In Table 1, material numbers 3 to 6 are the calcined ferrite powders according to the present invention, and material numbers 1 and 2 are comparative examples.

そして、材料番号１〜６に示すフェライト仮焼粉に対して、Ｘ線回折装置（リガク社製Ｍｉｎｉｆｌｅｘ２ ＣｏＫα線仕様）、およびＸ線検出器（リガク社製Ｄ／ｔｅＸ Ｕｌｔｒａ）を用いてＸ線回析を行なった。そのＸ線回折に基づく分析結果を表２に示す。

And X-ray | X_line using the X-ray-diffraction apparatus (Miniflex2 CoK (alpha) specification by Rigaku Corporation) and an X-ray detector (D / teX Ultra by Rigaku Corporation) with respect to the ferrite calcined powder shown to material number 1-6. Diffraction was performed. The analysis results based on the X-ray diffraction are shown in Table 2.

ここで、表２に示した分析結果を説明する前に、発明者らが行なった、フェライト仮焼粉末のＸ線回折について説明する。図１（Ａ）は材料番号１に係るフェライト仮焼粉末のＸ線回折パターンであり、図１（Ｂ）は材料番号５に係るフェライト仮焼粉末のＸ線回折パターンである。

Here, before explaining the analysis results shown in Table 2, the X-ray diffraction of the calcined ferrite powder performed by the inventors will be described. 1A is an X-ray diffraction pattern of the calcined ferrite powder according to material number 1, and FIG. 1B is an X-ray diffraction pattern of the calcined ferrite powder according to material number 5.

  In these figures, the intensity around 2θ = 41.2 ° is a diffraction peak due to the spinel phase (311: mirror index, the same applies hereinafter) of the calcined ferrite powder. The fact that the intensity of the diffraction peak near 2θ = 41.2 ° is larger than the other diffraction peaks means that most of each powder before calcination has changed into a spinel structure by calcination. Show.

  The intensity around 2θ = 50.7 ° is a diffraction peak of the NiO phase (200) of the calcined ferrite powder. When comparing FIG. 1A and FIG. 1B, a diffraction peak near 2θ = 50.7 ° is not seen in FIG. 1A, whereas in FIG. There is a diffraction peak around 50.7 °.

  In the ferrite calcined powder according to material number 1, there is no NiO in a state before calcining, and all of the NiO before calcining is called NiO constituting a part of the spinel structure (hereinafter referred to as “spinel type NiO”). ). On the other hand, in the ferrite calcined powder according to material number 5, there is NiO that does not change to the spinel structure (hereinafter referred to as “non-spinel type NiO”).

  In order to determine the amount of non-spinel-type NiO in the calcined ferrite powder (NS in Formula 1), first, the intensity ratio Rp of the diffraction peak corresponding to the NiO phase (hereinafter referred to as NiO phase intensity ratio Rp) is expressed by Formula 2. Defined.

Rp = Pn / (Ps + Pn + Pf + Pz) (Formula 2)
Intensity of diffraction peak around 2θ = 50.7 ° corresponding to Pn: NiO phase (200) (NiO phase intensity)
Ps: intensity of diffraction peak near 2θ = 41.2 ° corresponding to spinel phase (311) (spinel phase intensity)
Pf: Intensity of diffraction peak around 2θ = 38.5 ° corresponding to Fe ₂ O ₃ phase (104) (Fe ₂ O ₃ phase strength)
Pz: Intensity of diffraction peak around 2θ = 42.1 ° corresponding to ZnO phase (101) (ZnO phase intensity)
Returning to Table 2, the analysis result of the X-ray diffraction of the calcined ferrite powder will be described. Table 2 shows the Fe ₂ O ₃ phase strength Pf, spinel phase strength Pf, ZnO phase strength Pz, and NiO phase strength Pn read from the X-ray diffraction patterns of material numbers 1 to 6. In addition, the NiO phase intensity ratio Rp calculated based on Equation 2 is shown.

  The NiO phase strength ratio Rp indicates the proportion of non-spinel-type NiO in the ceramic calcined powder. The greater the NiO phase strength ratio Rp, the greater the amount NS of non-spinel NiO. Considering the amount per unit, the value of the NiO phase strength ratio Rp is equal to the value NS of the non-spinel-type NiO in 1 part by weight of the calcined ceramic powder. Can be replaced. That is, the relationship Rp = NS is established.

  On the other hand, the total amount Wn (part by weight) of NiO in 1 part by weight of the ferrite calcined powder is obtained by performing composition analysis on the calcined ferrite powder by wavelength dispersive X-ray fluorescence analysis (WD-XRF). It was. According to the wavelength dispersive X-ray fluorescence analysis, the total amount Wn of NiO can be obtained by combining the amount S of spinel NiO and the amount NS of non-spinel NiO. That is, there is a relationship of Wn = S + NS.

  FIG. 3 is an explanatory diagram showing how to determine the ratio Rns of non-spinel NiO expressed by Equation 1. The ratio Rns of non-spinel-type NiO is the ratio of the amount of NiO that has not changed to the spinel structure to the total amount of NiO. As shown in FIG. 3, the NiO phase intensity ratio Rp is determined by X-ray diffraction, and the total amount Wn of NiO is determined by wavelength dispersive X-ray fluorescence analysis. Then, after replacing the NiO phase intensity ratio Rp with the amount NS of non-spinel-type NiO, the amount NS of non-spinel-type NiO is divided by the total amount Wn (= S + NS) of NiO to obtain non-spinel after calcination A ratio Rns of the type NiO is obtained. The results thus obtained are shown in Table 3.

表３に示した非スピネル型ＮｉＯの量ＮＳは、材料番号１〜６のそれぞれのＮｉＯ相強度比Ｒｐの値をそのまま置き換えたものである。これらの非スピネル型ＮｉＯの量ＮＳを、ＮｉＯの合計量Ｗｎで除算することにより、非スピネル型ＮｉＯの比率Ｒｎｓを算出した。なお、ＮｉＯの合計量Ｗｎの値は、調合組成である仮焼前の混合物のＮｉＯ量（重量部）の値とほぼ一致するので、ＮｉＯの合計量Ｗｎを、仮焼前の混合物のＮｉＯ量とみなすことができる。実施例１では、仮焼前の混合物のＮｉＯ量が９．３５重量％であるので、ＮｉＯの合計量Ｗｎ＝０．０９３５として計算した。

The amount NS of the non-spinel type NiO shown in Table 3 is obtained by replacing the values of the NiO phase strength ratios Rp of the material numbers 1 to 6 as they are. By dividing the amount NS of these non-spinel-type NiOs by the total amount Wn of NiO, the ratio Rns of non-spinel-type NiO was calculated. In addition, since the value of the total amount Wn of NiO substantially coincides with the value of NiO amount (parts by weight) of the mixture before calcination, which is a blended composition, the total amount of NiO Wn is the amount of NiO of the mixture before calcination. Can be considered. In Example 1, since the NiO amount of the mixture before calcination was 9.35% by weight, the total amount of NiO was calculated as Wn = 0.0935.

  In Table 3, the ratio Rns of non-spinel NiO is, for example, Rns = 0.15 for material number 2 and Rns = 0.49 for material number 3. The difference in the value of Rns affects the density and magnetic permeability of the finished magnetic component.

  Next, a magnetic part produced using the calcined ferrite powder and a manufacturing process of the magnetic part will be described.

The calcined ferrite powder obtained by the above-described production method was put into a ball mill together with pure water and PSZ balls, and pulverized until the specific surface area (SSA) of the calcined ferrite powder was 7.5 m ² / g. Next, an organic binder (acrylic binder) or the like was added to the pulverized powder and mixed, and then a green sheet having a thickness of 25 μm was produced by a doctor blade method. A predetermined number of these green sheets were stacked and pressure-bonded under the conditions of a temperature of 60 ° C. and a pressure of 100 MPa, and then punched out with a mold to obtain a ring-shaped molded body. And after degreasing the ring-shaped molded object at the temperature of 400 degreeC, it heated up to 860 degreeC with the temperature increase rate of 5 degree-C / min, and also hold | maintained at the same temperature for 2 hours, and complete | finished the baking process. As a result, a ring-shaped magnetic component (ferrite bead) was produced. The dimensions of the magnetic component are a thickness of 0.5 mm, an outer diameter of 20 mm, and an inner diameter of 12 mm. Separately from this, the magnetic parts fired at different firing temperatures of 5 ° C. such as 865 ° C., 870 ° C., 875 ° C.,.

The density was measured using the Archimedes method for each magnetic component. Among them, a magnetic component having a density of 4.9 g / cm ³ or 4.6 / cm ³ was selected. The value of density 4.9 g / cm ³ or 4.6 / cm ³ is an average value in the frequency distribution in the production lot. The density of a general magnetic component is 5.0 g / cm ³ or more, whereas the density of a magnetic component this time is smaller than that.

  Next, the initial magnetic permeability μi at a frequency of 1 MHz was measured for the selected magnetic component. For this measurement, a magnetic material measuring jig (model number 16454A-S) and an impedance analyzer (model number E4991A) manufactured by Agilent Technologies were used. Table 4 shows the measurement results. In Table 4, material numbers 3 to 6 are magnetic parts using the calcined ferrite powder according to the present invention, and material numbers 1 and 2 are comparative examples.

表４に示すとおり、磁性部品の密度が４．９ｇ／ｃｍ³である場合、材料番号１、２の初透磁率μｉが２１０であるのに対し、材料番号３〜６の初透磁率μｉは２４０〜２８５であった。すなわち、本発明に係るフェライト仮焼粉末を用いた磁性部品は、比較例に比べて１５〜３６％高い初透磁率μｉを得ることができた。また、磁性部品の密度が４．６ｇ／ｃｍ³である場合、材料番号１、２の初透磁率μｉが１５０であるのに対し、材料番号３〜６の初透磁率μｉは１９０〜２３０であった。すなわち、本発明に係るフェライト仮焼粉末を用いた磁性部品は、比較例に比べて２７〜５３％高い初透磁率μｉを得ることができた。

As shown in Table 4, when the density of the magnetic parts is 4.9 g / cm ³ , the initial permeability μi of material numbers 1 and 2 is 210, whereas the initial permeability μi of material numbers 3 to 6 is 240-285. That is, the magnetic component using the calcined ferrite powder according to the present invention was able to obtain an initial permeability μi that was 15 to 36% higher than that of the comparative example. When the density of the magnetic component is 4.6 g / cm ³ , the initial permeability μi of the material numbers 1 and 2 is 150, whereas the initial permeability μi of the material numbers 3 to 6 is 190 to 230. there were. That is, the magnetic component using the calcined ferrite powder according to the present invention was able to obtain an initial permeability μi that was 27 to 53% higher than that of the comparative example.

  With reference to FIG. 4, the reason why in Example 1 a magnetic component having a low density after firing and a high initial permeability μi can be produced will be described. The reason is that a part of NiO prepared in the mixture before calcination remains in the spinel structure in a state where the ferrite calcination powder after calcination is not changed. If non-spinel-type NiO remains in the calcined ferrite powder, when the calcined ferrite powder is sintered into a magnetic part, part of the amount of heat applied is changed to a spinel structure. Used for. Therefore, as shown in FIG. 4, the progress of the sintering of the calcined ferrite powder can be delayed as compared with the comparative example, and the shrinkage during sintering can be suppressed accordingly. As a result, the density of the magnetic component can be reduced. In addition, if the progress of the sintering is delayed, the firing temperature of the calcined ferrite powder can be set higher than that of the comparative example, as shown in FIG. By setting the firing temperature high, grain growth is promoted in the sintering process of the calcined ferrite powder, and the initial permeability μi of the magnetic component can be increased. In addition, although shrinkage | contraction at the time of sintering progresses by raising a calcination temperature, the magnetic component of the small density substantially the same as a comparative example can be obtained by complete | finishing a calcination process in moderate time.

  Thus, by leaving NiO that has not changed to the spinel structure at a certain ratio in the calcined ferrite powder, the density of the magnetic parts after firing can be reduced and the initial permeability μi can be increased. As shown in Example 1 according to the present invention, a magnetic component having desired properties can be obtained by using a calcined ferrite powder having a non-spinel-type NiO ratio Rns of 0.49 or more.

  Further, the ratio Rns of non-spinel-type NiO in the calcined ferrite powder is preferably 0.49 or more and 0.98 or less, and more preferably 0.49 or more and 0.80 or less. This is because if the ratio Rns of non-spinel-type NiO is too large, the firing time for producing the magnetic component becomes long. Note that the ratio Rns of non-spinel NiO can be obtained by Equation 1 and Equation 2.

  Moreover, the ratio Rns of non-spinel-type NiO after calcination can be set to an appropriate value by setting the rate of temperature rise when producing the calcined ferrite powder to 100 ° C./min to 1000 ° C./min. . When a magnetic component is manufactured using the ferrite calcined powder manufactured at this temperature increase rate, the density of the magnetic component can be reduced and the initial permeability μi can be increased.

  More preferably, the rate of temperature rise when producing the calcined ferrite powder is 100 ° C./min or more and 500 ° C./min or less. This is because if the rate of temperature rise is too high, the ratio remaining as non-spinel-type NiO becomes too large, and the firing time for producing the magnetic component becomes long.

(Laminated coil component and manufacturing method thereof)
Example 2 shows an example in which the laminated coil component 10 is manufactured using the ferrite calcined powder of material number 5 shown in Example 1. Moreover, the example which produced the multilayer coil component 10 using the ferrite calcining powder of the material number 1 as a comparative example is also shown.

  First, a magnetic slurry was prepared by mixing an organic binder or the like with the ferrite calcined powder shown in Material No. 1 and Material No. 5. Next, a green sheet was formed by forming the magnetic slurry into a sheet. And the via hole was formed in the predetermined position of each green sheet using the laser processing machine. On the other hand, a conductive paste was prepared by mixing silver powder, varnish and organic solvent. This conductive paste was printed on the surface of the green sheet with a screen printer and filled with via holes. As a result, a coil pattern having a predetermined shape was formed on the green sheet.

  A plurality of green sheets on which the coil pattern was formed were stacked, and green sheets on which the coil pattern was not formed were stacked from both sides in the stacking direction to prepare a sheet stack. Thereafter, the sheet laminate was pressure-bonded under the conditions of a temperature of 60 ° C. and a pressure of 100 MPa to produce a laminate block, and this was cut into a predetermined size to produce a laminate component.

  The laminated parts were degreased by heating to 400 ° C. in the air, and then heated to the firing temperature shown in Table 5 at a temperature rising rate of 5 ° C./min in the air. Further, the baking treatment was finished by holding at the same temperature for 2 hours. As a result, a multilayer part including the inner conductor 12 in the magnetic part 11 was produced.

  On the other hand, a conductive paste for an external electrode containing silver powder, glass frit, varnish and an organic solvent was prepared. The external electrode conductive paste was applied to both ends of the laminated part and dried, and then baked at 750 ° C. to form the external electrode 13. Thereby, the laminated coil component 10 as shown in FIG. 2 was obtained. The outer diameter dimensions of the laminated coil component 10 are length L: 1.0 mm, width W: 0.5 mm, thickness T: 0.5 mm, and the number of turns of the coil of the inner conductor portion 12 is 10.5 turns. It was.

Here, the ferrite calcined powder of material number 5 is fired at a temperature of 885 ° C., and the laminated coil component 10 in which the density of the magnetic body portion 11 is 4.6 g / cm ³ is defined as component number S1, and the material number 5 The ferrite calcined powder was fired at a temperature of 895 ° C., and the laminated coil component 10 in which the density of the magnetic part 11 was 4.9 g / cm ³ was designated as part number S2. Further, as a comparative example, the ferrite calcined powder of material number 1 is fired at a temperature of 880 ° C., and the laminated coil component 10 in which the density of the magnetic body portion 11 is 4.6 g / cm ³ is defined as a component number M1. No. 1 ferrite calcined powder was fired at a temperature of 910 ° C., and the laminated coil component 10 in which the density of the magnetic part 11 was 4.9 g / cm ³ was designated as part number M2.

  Fifty part numbers S1, S2, M1, and M2 were produced, and the impedance Z at a frequency of 100 MHz was measured for each part number. For this measurement, an impedance analyzer (model number E4991A) manufactured by Agilent Technologies was used. Table 5 shows the average value of the impedance Z obtained for each part number. In Table 5, the density and initial permeability μi of the magnetic component shown in Example 1 are described as the density and initial permeability μi of the magnetic body 11 alone.

部品番号Ｓ１、Ｓ２は、磁性体部１１の密度が小さく、初透磁率μｉも高いので、大きなインピーダンスを得ることができた。これに対し、部品番号Ｍ２では、初透磁率μｉは高いのに、得られるインピーダンスＺが低下した。その要因としては、磁性体部１１の密度が大きく、磁性体部１１の内部に応力歪みが発生したためと考えられる。また、部品番号Ｍ１では、磁性体部１１の密度は小さいが、同じ密度の部品番号Ｓ１に比べると、初透磁率μｉが小さいので、得られるインピーダンスＺが小さくなった。

In the part numbers S1 and S2, since the density of the magnetic part 11 is small and the initial permeability μi is high, a large impedance can be obtained. On the other hand, in the part number M2, although the initial permeability μi is high, the obtained impedance Z is lowered. The reason is considered to be that the density of the magnetic body portion 11 is large and stress strain is generated inside the magnetic body portion 11. Moreover, in the part number M1, although the density of the magnetic body part 11 is small, compared with the part number S1 of the same density, since the initial permeability μi is small, the obtained impedance Z is small.

  Thus, by using the ferrite calcined powder shown in Example 1, it is possible to produce the multilayer coil component 10 including the magnetic body portion 11 that has a low density after firing and can obtain a high magnetic permeability. . Thereby, while reducing stress distortion, the multilayer coil component 10 which can obtain a big impedance can be obtained.

  In Example 2, only the multilayer coil component 10 manufactured using the material number 5 is illustrated, but the impedance Z is also about 1100Ω in the multilayer coil components manufactured using the material numbers 3, 4, and 6. It is confirmed that

  Each of the embodiments described above does not limit the invention described in the claims, and various modifications can be made within the scope where the same technical idea is recognized. For example, the multilayer coil component is not limited to a single component including an inductor, and may be a composite component including a capacitor and a resistor in addition to the inductor. The multilayer coil component may have a structure in which the density of the magnetic body portion around the inner conductor portion is small and the density of the outer magnetic body portion away from the inner conductor portion is large.

10: Laminated coil component 11: Magnetic body portion 12: Internal conductor portion 13: External electrode

Claims (4)

A ferrite calcined powder containing at least Fe, Ni and Zn as elements,
Ni has what exists as NiO constituting a part of the spinel structure and what exists as NiO not changed to the spinel structure,
NS is the amount of NiO that has not changed to a spinel structure in 1 part by weight of the calcined ferrite powder,
When the total amount of NiO in 1 part by weight of the ferrite calcined powder is Wn,
A ferrite calcined powder characterized in that the ratio Rns of NiO not changed to a spinel structure represented by NS / Wn is 0.49 or more. A laminated coil component comprising: a magnetic body portion including a magnetic material; and a coil-shaped inner conductor portion provided inside the magnetic body portion,
2. The multilayer coil component according to claim 1, wherein the magnetic part is formed by firing the calcined ferrite powder according to claim 1. A method for producing a calcined ferrite powder according to claim 1,
A mixture preparation step for preparing a powdery mixture containing at least Fe ₂ O ₃ , NiO and ZnO;
A calcining step of calcining the mixture at a temperature rising rate of 100 ° C./min to 1000 ° C./min;
A method for producing a calcined ferrite powder. To the ferrite calcined powder produced by the method for producing a calcined ferrite powder according to claim 3, a slurry producing step of producing a magnetic slurry by mixing an organic binder,
A sheet forming step of forming a green sheet by forming the magnetic slurry into a sheet;
A coil pattern forming step of forming a coil pattern on the green sheet;
A laminated body forming step of forming a laminated body by laminating a plurality of the green sheets on which the coil patterns are formed;
A firing step of firing the laminate;
A method for manufacturing a laminated coil component comprising:

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