JP4830259B2 - Manufacturing method of multilayer ceramic electronic component - Google Patents

Description

The present invention relates to a method of manufacturing a product layer ceramic electronic components, more particularly, initial permeability μi and Q value is high, the product layer ceramic that can be produced variations of such Iseki layer ceramic electronic components in chip characteristics The present invention relates to a method for manufacturing an electronic component.

  Conventionally, ferrite sintered bodies have been used as inductor materials for multilayer ceramic electronic components such as magnetic core materials and multilayer chip inductors because of their excellent magnetic properties.

  In the case of a multilayer chip inductor, in general, a ferrite layer and a conductor pattern are sequentially laminated to form a laminate in which a coil composed of laminated and connected conductor patterns is formed in ferrite, and after firing, Each external terminal connected to the coil is formed and manufactured. In general, Ni—Cu—Zn ferrite material, Ni—Zn ferrite material, or the like is used as the ferrite material of the multilayer chip inductor, and Ag having high electrical conductivity is used as the conductor material.

  In addition, electronic devices are becoming smaller, higher performance, higher reliability, and multifunctional, and ferrite parts and the like used therefor are required to be further reduced in size and characteristics. In response to this, for example, in the case of an inductor material used for a multilayer chip inductor, an attempt has been made to improve characteristics by adding glass to a ferrite raw material. However, the properties of ferrite such as initial permeability μi and Q value have not been sufficiently improved.

Therefore, the applicant of the present invention has a high initial permeability μi and Q value by adding boron carbide (B ₄ C) powder to the ferrite raw material in Patent Document 1, and is suitable for inductors such as multilayer chip inductors. A method for producing a sintered ferrite body used in the present invention was proposed.

JP 2000-233967 A

However, in the case of the ferrite sintered body described in Patent Document 1, a ferrite sintered body having high initial magnetic permeability μi and Q value can be obtained by adding B ₄ C powder to the ferrite raw material. It was found that even when the amount of B ₄ C powder added was the same, the initial permeability μi of the ferrite sintered body varied or deteriorated depending on the storage state of the B ₄ C powder.

The present invention has been made to solve the above problems, the initial permeability μi and Q value is high, to provide a method of manufacturing variation or degradation Ru can be suppressed product layer ceramic electronic component chip characteristics The purpose is that.

The present inventors have studied a result the B _{4 C} powder during storage, B _{4 C} powder during storage, although stable by oxidation film formed on the particle surface, the degree of oxidation by storage conditions I found it different. In the oxidation of B ₄ C, boric acid and boron oxide are generated as impurities, and as the amount of these impurities increases with the progress of oxidation, the permeability and chip characteristics of the ferrite sintered body deteriorate due to these impurities. I found out that In particular, when the present inventors conducted X-ray diffraction analysis of B ₄ C powder, boric acid and boron oxide had a predetermined ratio with respect to the total amount of all peaks of B ₄ C powder in terms of X-ray diffraction intensity. It has been found that the magnetic permeability of the ferrite sintered body deteriorates remarkably when exceeding. The reason for this is that when the degree of oxidation of B ₄ C increases, when the slurry is prepared by adding B ₄ C powder to the ferrite raw material, it reacts with the hydroxyl groups in the solvent and the B ₄ C powder agglomerates. It is conceivable that a uniform sheet cannot be formed by gelation. In this specification, boron carbide powder containing impurities such as boric acid and boron oxide is defined as boron carbide powder (B ₄ C powder), and is distinguished from boron carbide (B ₄ C) containing no impurities.

The present invention has been made based on the above findings, the production method of a multilayer ceramic electronic component according to claim 1, an organic solvent and a step of preparing a starting ferrite, a solvent which have a hydroxyl group in the starting ferrite And the boron carbide powder is analyzed by X-ray diffraction, and the total amount of peaks indicating the X-ray diffraction intensities of boron oxide and boric acid contained as impurities is all X of the boron carbide powder. in addition the step of selecting a boron carbide powder within 10% in the X-ray diffraction intensity ratio to the total amount of peaks indicating ray diffraction intensity, the bus inductor and the boron carbide powder in the ferrite raw material after the wet pulverization Kneading to obtain a ceramic slurry, forming the ceramic slurry into a sheet to obtain a ceramic green sheet, and the ceramic green sheet. Forming a laminate by a predetermined number of stacked bets, it is characterized in that and a step of firing the laminate.

  Thus, the ferrite raw material used in the present invention is not particularly limited, and examples of the ferrite raw material include Ni-Cu-Zn-based ferrite and Ni-Zn-based ferrite, among Ni, Cu and Zn. Ferrite containing at least two kinds of elements is preferably used. These ferrite raw materials may contain additives such as Mn and Sn.

In the present invention, the storage state of the boron carbide powder (B ₄ C powder) is managed by X-ray diffraction analysis, and boron oxide and boric acid contained as impurities are X-ray diffraction intensities of all peaks of the boron carbide powder. B ₄ C powder within 10% of the total amount is selected and used. B 4 _C the powder boron oxide and boric acid are contained as impurities in more than 10% of the total amount of all the peaks of the B _{4 C} powder X-ray diffraction intensity, electromagnetic μi like ferrite sintered body There may be variations in characteristics. In the present invention, boron oxide and boric acid contained as impurities include 0% B ₄ C in terms of X-ray diffraction intensity with respect to the total amount of all peaks of the B ₄ C powder. It is difficult to completely prevent ₄ C oxidation. In order to suppress the oxidation of B ₄ C, it is preferable to store and manage the B ₄ C powder in a non-oxidizing atmosphere such as nitrogen gas.

Here, boron oxide is a general term for B ₂ O ₃ , B ₇ O, B ₁₃ O ₂ , B ₆ O, BO, and B ₄ O ₅ . Since most of the boron oxide generated during storage of the B ₄ C powder is B ₂ O ₃ , the other boron oxide is extremely small and almost negligible. Boric acid is a general term for orthoboric acid, metaboric acid, hypoboric acid, and the like. Since most of the boric acid produced during storage of the B ₄ C powder is orthoboric acid, it is considered that other boric acid is hardly contained. In addition, since the peak positions of boron oxide and boric acid match in X-ray diffraction, whether the X-ray diffraction intensity for B ₄ C powder is either boron oxide or boric acid alone or the total amount of both is determined. I can't distinguish. Further, since the peak width of the X-ray diffraction intensity varies depending on the crystal state of the B ₄ C powder, the integral width of the peak when obtaining the X-ray diffraction intensity is different.

According to the onset bright, it is possible to initial permeability μi and Q value is high, to provide a method of manufacturing variation or degradation Ru can be suppressed product layer ceramic electronic component chip characteristics.

  In this embodiment, first, each of the ferrite sintered bodies of Examples 1 to 4 and Comparative Examples 1 and 2 was prepared in the following manner using the method for producing a ferrite sintered body of the present invention.

(1) Preparation of Ceramic Raw Material First, Fe ₂ O ₃ , ZnO, CuO and NiO powders were prepared as ferrite raw materials. Then, each powder was weighed so that Fe ₂ O ₃ was 48.7 mol%, ZnO was 26.9 mol%, CuO was 10.5 mol%, and the rest was NiO. Next, these powders were wet mixed by a ball mill and dried, and then calcined at 700 ° C. to obtain a ferrite raw material. Thereafter, this calcined ferrite raw material was wet-ground by a ball mill. Under the present circumstances, the organic solvent containing the solvent which has hydroxyl groups, such as aqueous type | system | group or alcohol, can be used as a solvent.

(2) Selection of B ₄ C powder and preparation of ceramic green sheet After performing X-ray diffraction analysis on the B ₄ C powder in storage, boron oxide and boric acid contained as impurities are contained in the B ₄ C powder. to sort B _{4 C} powder within 10% relative to the total weight of all the peaks of the B _{4 C} powder X-ray diffraction intensity. As shown in Table 1 in the present embodiment, it screened 1.07 percent B _{4 C} powder to the total amount of all the peaks of the B _{4 C} powder boron oxide and boric acid in X-ray diffraction intensity, this 80 ppm by weight of B ₄ C powder was added to the ferrite raw material after wet pulverization, wet-mixed with a ball mill, a binder was added to form a slurry, and then a ceramic green sheet was produced by a doctor blade method.

(3) Preparation of ferrite sintered body The ceramic green sheets were laminated and pressure-bonded, and cut into a toroidal ring having an outer diameter of 20 mm, an inner diameter of 10 mm, and a thickness of 1 mm. Then, this toroidal ring was fired at 900 ° C. for 150 minutes to obtain a ferrite sintered body.

(4) Measurement of initial permeability μi Next, the ferrite sintered body was measured for μi under the condition of a measurement frequency of 10 kHz using an impedance analyzer, and the results are shown in Table 1.

In this example, as shown in Table 1, out of the B ₄ C powder being stored, boron oxide and boric acid contained as impurities are X-ray diffraction intensity with respect to the total amount of all peaks of the B ₄ C powder. 4.32% B ₄ C powder was selected, and a ferrite sintered body was prepared in the same manner as in Example 1 except that this B ₄ C powder was used. The results are shown in Table 1.

In this example, as shown in Table 1, out of the B ₄ C powder being stored, boron oxide and boric acid contained as impurities are X-ray diffraction intensity with respect to the total amount of all peaks of the B ₄ C powder. 7.71% B ₄ C powder was selected, and a ferrite sintered body was produced in the same manner as in Example 1 except that this B ₄ C powder was used. The results are shown in Table 1.

In this example, as shown in Table 1, out of the B ₄ C powder being stored, boron oxide and boric acid contained as impurities are X-ray diffraction intensity with respect to the total amount of all peaks of the B ₄ C powder. 9.68% B ₄ C powder was selected, and a ferrite sintered body was produced in the same manner as in Example 1 except that this B ₄ C powder was used. The results are shown in Table 1.

Also, more than from the B _{4 C} powder during storage, 10% of the total amount of all the peaks of boron oxide and boric acid B _{4 C} powder X-ray diffraction intensity as impurity B _{4 C} powder Ferrite sintered bodies of Comparative Examples 1 and 2 using the above were prepared. As shown in Table 1, the 10.86% of B _{4 C} powder to the total amount of all the peaks of boron oxide and boric acid B _{4 C} powder X-ray diffraction intensity as impurity in Comparative Example 1 used, the embodiment except for using 12.19% of B _{4 C} powder to the total amount of all the peaks of boron oxide and boric acid B _{4 C} powder X-ray diffraction intensity as impurity in Comparative example 2 A ferrite sintered body was produced in the same manner as in Example 1. Thereafter, μi of each ferrite sintered body of Comparative Examples 1 and 2 was measured, and the results are shown in Table 1.

According to the results shown in Table 1, boron oxide and boric acid contained as impurities are X-ray diffraction intensities of B ₄ C powder within 10% of the total amount of all peaks of B ₄ C powder. In the case of the added Examples 1 to 4, ferrite sintered bodies having high μi were obtained. Comparative example In contrast, boron oxide and boric acid are contained as impurities and the sum of all the more than 10% of B _{4 C} powder relative amount of the peak of B _{4 C} powder X-ray diffraction intensity is added to the ferrite material In the case of 1 and 2, it was found that μi of the ferrite termination body was remarkably lowered.

  Next, in this embodiment, the multilayer inductor shown in FIG. 1 was manufactured using the same raw materials as those in the above examples and comparative examples.

  For example, as shown in FIG. 1, the multilayer ceramic electronic component 10 of the present embodiment includes a ferrite sintered body 11, a coil 12 formed in the ferrite sintered body 11, and upper and lower electrode portions 12 </ b> A of the coil 12. , 12B and a pair of left and right external electrodes 13A, 13B covering both end faces of the sintered body 11, and configured as a multilayer inductor. The coil 12 includes a coil conductor 121 formed in a plurality of upper and lower stages in the horizontal direction and a via-hole conductor 122 that electrically connects the upper and lower coil conductors 121, and is formed as a rectangular spiral extending in the vertical direction. ing. In this embodiment, the multilayer inductors of Examples 7 to 10 and Comparative Examples 11 and 12 were produced in the following manner.

(1) Production of Multilayer Inductor In this example, as shown in Table 2, after a via hole was formed at a predetermined position of the ceramic green sheet produced in Example 1, the upper surface of this ceramic green sheet was used by screen printing or the like. A predetermined coil pattern was formed. Given the coil pattern is required number laminating ceramic green sheets formed, after laminating the ceramic green sheets where the coil pattern is not formed on both surfaces of the upper and lower, which was pressed at a pressure of 1000 kgf / cm ² A crimping block was formed. Thereby, the coil pattern of each layer is connected by the via hole to form a laminated coil. And this press-bonded block was cut into a predetermined size to obtain a laminate. Next, after degreasing the laminated body, the laminated body after degreasing is fired at 900 ° C. to obtain a sintered body. After the end face treatment of the sintered body, the conductive paste is applied to both end faces. It was applied and baked at 700 ° C. to form external electrodes. As a result, the multilayer inductor of Example 5 in which the coil was built in the ferrite sintered body was obtained.

(2) Measurement of Inductance and Impedance of Multilayer Inductor Next, with respect to the above multilayer inductor, an inductance L at 1 MHz and an impedance Z at 100 MHz were measured, and the results are shown in Table 2.

  In this example, as shown in Table 2, a laminated inductor was produced in the same manner as in Example 5 except that the ceramic green sheet produced in Example 2 was used, and the inductance L and impedance Z of this laminated inductor were implemented. The measurement was performed under the same conditions as in Example 5, and the results are shown in Table 2.

  In this example, as shown in Table 2, a laminated inductor was produced in the same manner as in Example 5 except that the ceramic green sheet produced in Example 3 was used, and the inductance L and impedance Z of this laminated inductor were implemented. The measurement was performed under the same conditions as in Example 5, and the results are shown in Table 2.

  In this example, as shown in Table 2, a laminated inductor was produced in the same manner as in Example 5 except that the ceramic green sheet produced in Example 4 was used, and the inductance L and impedance Z of this laminated inductor were implemented. The measurement was performed under the same conditions as in Example 5, and the results are shown in Table 2.

  Further, as shown in Table 2, the ceramic green sheets produced in Comparative Examples 1 and 2 were used for comparison of the multilayer inductors of Examples 5 to 8, and in the same manner as in Example 5, Comparative Examples 3 and 4 were used. A multilayer inductor was fabricated. And the inductance L and impedance Z of the multilayer inductor of the comparative examples 3 and 4 were measured on the same conditions as Example 5, and this result was shown in Table 2.

According to the results shown in Table 2, the ferrite a B _{4 C} powder boron oxide and boric acid was managed within 10% relative to the total weight of all the peaks of the B _{4 C} powder X-ray diffraction intensity contained as impurities In the case of Examples 5 to 8 added to the raw material, a multilayer inductor having high impedance was obtained. Comparative example In contrast, boron oxide and boric acid are contained as impurities and the sum of all the more than 10% of B _{4 C} powder relative amount of the peak of B _{4 C} powder X-ray diffraction intensity is added to the ferrite material In cases 3 and 4, it was found that the impedance of the multilayer inductor was remarkably lowered.

In the above embodiment, the component composition of the ferrite raw material powder is 48.7 mol% Fe ₂ O ₃ , 26.9 mol% ZnO, 10.5 mol% CuO, and the rest NiO. However, the present invention is not limited to this composition component. In addition to Ni—Cu—Zn ferrite, Ni—Zn ferrite, etc., at least two of Ni, Cu and Zn The same effect can be expected even in the ferrite containing the above elements. The same effect can also be expected in ferrites containing additives such as Mn and Sn in the ferrite raw material.

  The present invention can be suitably used in a method for manufacturing a ferrite sintered body used for a multilayer inductor, a multilayer LC composite component, and the like, and a method for manufacturing a multilayer ceramic electronic component including a ferrite sintered body.

1 is a perspective view illustrating a multilayer ceramic electronic component according to an embodiment of the present invention.

Explanation of symbols

10 Multilayer Ceramic Electronic Component 11 Ferrite Sintered Body 12 Coil (Internal Electrode)

Claims (1)

Preparing a ferrite raw material;
A step of performing wet pulverization using an organic solvent containing a solvent having a hydroxyl group in the ferrite raw material;
When the boron carbide powder is analyzed by X-ray diffraction, the total amount of peaks indicating the X-ray diffraction intensity of each of boron oxide and boric acid contained as impurities is the total amount of peaks indicating all the X-ray diffraction intensities of the boron carbide powder. Selecting a boron carbide powder having an X-ray diffraction intensity ratio of 10% or less relative to
Obtaining a ceramic slurry was kneaded to bus inductor and the boron carbide powder in the ferrite raw material after the wet pulverization,
Forming the ceramic slurry into a sheet to obtain a ceramic green sheet;
A step of laminating a predetermined number of the ceramic green sheets to form a laminate;
Firing the laminate,
A method for producing a multilayer ceramic electronic component comprising:

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