JP3956695B2 - Manufacturing method of multilayer ceramic electronic component - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a multilayer ceramic electronic component such as a multilayer ceramic capacitor, and more particularly to a method for manufacturing a multilayer ceramic electronic component implemented using a ceramic raw material powder containing a metal hydroxide. .
[0002]
[Prior art]
A multilayer ceramic capacitor as an example of a multilayer ceramic electronic component is generally manufactured as follows.
[0003]
First, a ceramic slurry is produced by mixing the ceramic raw material powder with a vehicle comprising a solvent and a binder, and a ceramic green sheet is produced by forming the ceramic slurry into a sheet.
[0004]
Next, a conductor layer for an internal conductor functioning as an internal electrode is formed on a specific one of the plurality of ceramic green sheets manufactured as described above, for example, by printing a conductive paste.
[0005]
Next, a plurality of ceramic green sheets with the conductor layers as described above are laminated, and ceramic green sheets without a conductor layer are laminated at both ends in the lamination direction, and these ceramic green sheets are crimped. By doing so, a raw laminate is produced. In this raw laminated body, conductor layers for a plurality of internal conductors are formed at positions facing each other with a ceramic green sheet interposed therebetween.
[0006]
Next, the raw laminate is degreased and then fired.
[0007]
Next, an external electrode is formed on the outer surface of the fired laminate so as to be electrically connected to a specific conductor layer for the inner conductor.
[0008]
[Problems to be solved by the invention]
For the ceramic raw material powder described above, a metal hydroxide is used as at least a part of the starting material, or water is used while using magnesium oxide or a rare earth element oxide as at least a part of the starting material. Some are obtained by wet-mixing and pulverizing, followed by heat-drying.
[0009]
In such a case, when the raw laminate manufactured as described above is degreased, delamination may occur in the laminate after the degreasing step.
[0010]
The cause of the occurrence of the above delamination is that stress is generated in the laminate due to an endothermic reaction when H ₂ O is separated from the metal hydroxide contained in the ceramic raw material powder during the degreasing process.
[0011]
As described above, not only when using a metal hydroxide as at least a part of the starting material of the ceramic raw material powder, but also when using magnesium oxide or rare earth element oxide as at least a part of the starting material, Since these magnesium oxides and rare earth element oxides are changed to hydroxides at the stage from the wet mixing / pulverization step using water to the heat drying step, the same problem occurs.
[0012]
Therefore, an object of the present invention is to provide a method for manufacturing a multilayer ceramic electronic component that can solve the above-described problems.
[0013]
[Means for Solving the Problems]
Briefly speaking, the present invention is to remove metal hydroxide from a ceramic raw material powder containing metal hydroxide in advance, and then use the ceramic raw material powder for the production of multilayer ceramic electronic components. It is characterized by performing heat treatment at a specific temperature for removal.
[0014]
More specifically, the method for manufacturing a multilayer ceramic electronic component according to the present invention first includes a step of heat treating a ceramic raw material powder containing a metal hydroxide. The temperature applied in this heat treatment step is such that when the ceramic raw material powder is subjected to X-ray diffraction analysis, the peak of the metal hydroxide disappears and the production of a composite other than the metal oxide contained in the metal hydroxide is generated. The temperature is set to a temperature applied in the heat treatment for the ceramic raw material powder so as to obtain an analysis result that is not confirmed.
[0015]
Next, the ceramic raw material powder after the heat treatment is mixed with a vehicle composed of an organic solvent and a binder to produce a ceramic slurry, and the ceramic slurry is formed into a sheet to produce a ceramic green sheet. A conductive layer for an internal conductor is formed on the sheet, and a plurality of ceramic green sheets are laminated to produce a raw laminate, and the raw laminate is degreased and then fired. After that, the multilayer ceramic electronic component is manufactured.
[0016]
According to another aspect of the method for manufacturing a multilayer ceramic electronic component according to the present invention, a ceramic raw material powder containing a metal hydroxide is heat-treated at an appropriate temperature, and then the heat-treated ceramic raw material powder is subjected to X-ray diffraction analysis. And a ceramic raw material in which the peak of the metal hydroxide disappears and an analysis result in which formation of a composite other than the metal oxide contained in the metal hydroxide is not confirmed is obtained in the X-ray diffraction analysis And a step of finding a temperature applied in the heat treatment of the powder.
[0017]
Further, after the above preparation step, the raw material powder containing the metal hydroxide is heat-treated at the temperature found by X-ray diffraction analysis, and the heat-treated ceramic raw material powder is composed of an organic solvent and a binder. A step of producing a ceramic slurry by mixing with a vehicle, a step of producing a ceramic green sheet by forming the ceramic slurry into a sheet, and forming a conductor layer for the internal conductor on the ceramic green sheet A manufacturing stage process is carried out including a process, a process of producing a raw laminate by laminating a plurality of ceramic green sheets, and a step of degreasing and then firing the raw laminate.
[0018]
Normally, the above-described preparation stage process is not performed every time a multilayer ceramic electronic component is manufactured, but when the mass production system is entered after the preparation stage process is performed once, the manufacturing stage process is performed multiple times. Repeated.
[0019]
Examples of the metal hydroxide include Mg (OH) ₂ , Ca (OH) ₂ , La (OH) ₃ , Ce (OH) ₃ , Pr (OH) ₃ , Nd (OH) ₃ , Pm (OH) ₃ , It is at least one of Sm (OH) ₃ , Eu (OH) ₃ and Gd (OH) ₃ , particularly preferably Gd (OH) ₃ .
[0020]
The method for producing a multilayer ceramic electronic component according to the present invention is particularly advantageously applied in the production of a multilayer ceramic capacitor.
[0021]
In the above case, in the step of forming the conductor layer for the inner conductor on the ceramic green sheet, the conductor layer for the inner conductor is on each of the plurality of ceramic green sheets, and a raw laminate is produced. At a position facing each other with the ceramic green sheet interposed therebetween. Also, after the step of firing the raw laminate, a step of forming an external electrode on the outer surface of the fired laminate so as to be electrically connected to a specific conductor layer for the inner conductor Is further implemented.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view schematically showing a multilayer ceramic capacitor 1 as an example of a multilayer ceramic electronic component manufactured by the manufacturing method according to the present invention.
[0023]
The multilayer ceramic capacitor 1 includes a multilayer body 2. The multilayer body 2 includes a plurality of dielectric ceramic layers 3 to be laminated and a plurality of internal electrodes 4 and 5 as internal conductors respectively formed along a plurality of specific interfaces between the plurality of dielectric ceramic layers 3. It is composed with.
[0024]
The internal electrodes 4 and 5 are formed at positions facing each other with the dielectric ceramic layer 3 interposed therebetween, and the internal electrode 4 drawn to one end face 6 of the multilayer body 2 and the internal electrode 5 drawn to the other end face 7 are formed. Are alternately arranged inside the laminate 2.
[0025]
External electrodes 8 and 9 are formed on the end faces 6 and 7 of the laminate 2 so as to be electrically connected to the internal electrodes 4 and 5, respectively. The external electrodes 8 and 9 may be plated with nickel, copper or the like as required, and further plated with solder, tin or the like.
[0026]
The multilayer body 2 provided in such a multilayer ceramic capacitor 1 is obtained by degreasing the raw state and then firing it. The raw laminate 2 has a structure in which a raw dielectric ceramic layer 3 and a conductor layer to be each of the internal electrodes 4 and 5 are laminated.
[0027]
Next, a method for manufacturing the multilayer ceramic capacitor 1 will be described.
[0028]
First, a ceramic raw material powder for the ceramic constituting the dielectric ceramic layer 3 is prepared. This ceramic raw material powder includes, for example, Mg (OH) ₂ , Ca (OH) ₂ , La (OH) ₃ , Ce (OH) ₃ , Pr (OH) ₃ , Nd (OH) ₃ , Pm (OH) ₃ , It contains a metal hydroxide such as at least one of Sm (OH) ₃ , Eu (OH) ₃ and Gd (OH) ₃ .
[0029]
When the metal hydroxide is a metal hydroxide used as at least a part of the starting material of the ceramic raw material powder, or the ceramic raw material powder is oxidized with magnesium oxide or rare earth element in at least a part of the starting material. When it is a product obtained by wet mixing / pulverization using water and drying after using the product, it is a metal hydroxide produced in the stage from the wet mixing / pulverization step to the heat drying step There is.
[0030]
The ceramic raw material powder containing such metal hydroxide is then heat-treated to remove the metal hydroxide. The temperature applied in this heat treatment step is such that when the ceramic raw material powder is subjected to X-ray diffraction analysis, the peak of the metal hydroxide disappears and the production of a composite other than the metal oxide contained in the metal hydroxide is generated. The temperature is set to a temperature applied in the heat treatment for the ceramic raw material powder so as to obtain an analysis result that is not confirmed.
[0031]
In addition, as mentioned above, the temperature applied in the heat treatment step was not defined by a specific temperature range based on numerical limitation because the temperature satisfying the above-mentioned conditions depends on the type of metal hydroxide. This is because they are different.
[0032]
Further, in order to determine the temperature applied in the heat treatment process, the composition of the ceramic raw material powder is determined, and before entering the manufacturing stage of the multilayer ceramic capacitor 1, the following process is performed as a preparation stage process.
[0033]
That is, a ceramic raw material powder containing a metal hydroxide is heat-treated at an appropriate temperature, and then the heat-treated ceramic raw material powder is subjected to X-ray diffraction analysis. In addition, in the X-ray diffraction analysis, for the ceramic raw material powder in which the metal hydroxide peak disappears and an analysis result is obtained in which the formation of a composite other than the metal oxide contained in the metal hydroxide is not confirmed. The temperature applied in the heat treatment is found, and the temperature thus found is adopted as the temperature applied in the step of heat-treating the ceramic raw material powder containing the metal hydroxide.
[0034]
Next, the ceramic raw material powder after the heat treatment is mixed with an organic binder in an organic solvent, thereby producing a ceramic slurry.
[0035]
Next, a ceramic green sheet to be the dielectric ceramic layer 3 is produced by forming the ceramic slurry into a sheet.
[0036]
Next, a conductor layer for the internal electrode 4 or 5 is formed on each of the plurality of ceramic green sheets by, for example, screen printing using a conductive paste.
[0037]
Next, a plurality of ceramic green sheets on which conductor layers are formed are stacked, and ceramic green sheets on which conductor layers are not formed are stacked on both ends in the stacking direction, thereby producing a raw laminate. In the step of forming the conductor layer on the ceramic green sheet described above, when the raw laminate is produced in this way, the conductor layer is formed at a position facing the ceramic green sheet.
[0038]
Next, the process of degreasing and then baking the raw laminate is performed. In this degreasing step, as described above, since the metal hydroxide has already been removed from the ceramic raw material powder, there is no endothermic reaction when H ₂ O leaves from the metal hydroxide. Delamination caused by reaction stress is not generated in the laminate.
[0039]
As a result of the above-described firing step, the multilayer body 2 for the multilayer ceramic capacitor 1 shown in FIG. 1 is obtained. External electrodes 8 and 9 are formed on the outer surface of the laminate 3 and on the end faces 6 and 7 so as to be electrically connected to the internal electrodes 4 and 5, respectively. If necessary, the external electrodes 8 and 9 may be plated with nickel, copper or the like, and further plated with solder, tin or the like.
[0040]
The multilayer ceramic capacitor 1 is completed as described above.
[0041]
As described above, the ceramic raw material powder is heat-treated, and then X-ray diffraction analysis is performed, and the temperature applied in the heat treatment for removing the metal hydroxide is found from the result of the X-ray diffraction analysis. The preparation stage process does not need to be performed every time the subsequent production stage process, and may be performed only once for each composition of the ceramic raw material powder to be used. Therefore, in the actual production of the multilayer ceramic capacitor 1, after the preparation stage process is performed once, the production stage process is repeated a plurality of times.
[0042]
Next, the present invention will be described based on more specific experimental examples.
[0043]
Gd ₂ O ₃ powder was blended with BaTiO ₃ powder so as to be a proportion of 10% by weight, and wet-mixed and pulverized in a polypot with PSZ (partially stabilized zirconia) cobblestone and pure water until uniform. Next, the mixed and pulverized slurry was evaporated and dried by a dryer set at a temperature of 130 ° C. to obtain a ceramic raw material powder.
[0044]
FIG. 2 shows the result of X-ray diffraction analysis of the ceramic raw material powder. The X-ray diffraction analysis results shown in FIG. 2 were performed under the conditions of wavelength CuKα ray, scanning speed of 2 ° / min, and sampling width of 0.02 °.
[0045]
When X-ray diffraction analysis of the ceramic raw material powder after evaporation and drying is performed, a peak of Gd (OH) ₃ is observed between 2θ = 27 ° and 42 ° as shown in “(a) Before heating” in FIG. was detected. Which, when heated with Gd ₂ O ₃ with water, which indicates that the Gd ₂ O ₃ is changed to the Gd (OH) _3.
[0046]
The result of X-ray diffraction analysis after the above-mentioned heat-dried ceramic raw material powder is heat-treated in a heat treatment furnace at 500 ° C. for 2 hours is shown in “(b) After heating” in FIG. ing. Thus, as can be seen from the X-ray diffraction chart of the ceramic raw material powder after heating at 500 ° C., the peak of Gd (OH) ₃ disappears between 2θ = 27 ° and 42 °, and instead, Gd ₂ O ₃ peaks appeared. Moreover, there was no substantial change in other peaks.
[0047]
This is because when Gd (OH) ₃ was heated at a temperature of 500 ° C., H ₂ O was released and returned to Gd ₂ O ₃ , and at the temperature of 500 ° C., other chemical synthesis reactions occurred. This is because it did not occur. This shows that the temperature applied in the heat treatment for removing Gd (OH) ₃ from the ceramic raw material powder is suitably at least 500 ° C.
[0048]
Next, the following process is carried out for each of the ceramic raw material powder after evaporation drying described above, which has been heat-treated at a temperature of 500 ° C. and which has not been subjected to such heat treatment. A multilayer ceramic capacitor was obtained.
[0049]
That is, each ceramic raw material powder is mixed with PSZ cobblestone, toluene, ethyl alcohol and a binder in a polypot until uniform, and after obtaining a ceramic slurry, the ceramic green sheet is formed by forming it into a sheet shape. Obtained.
[0050]
Next, a conductive paste containing nickel as a conductive component is printed on the ceramic green sheet to form a conductor layer for the internal electrode, and a plurality of ceramic green sheets including the conductor layer thus formed are formed. A green laminate having a length of 5.7 mm, a width of 5.0 mm, and a thickness of 3.0 mm was produced through the steps of laminating and pressing the ceramic green sheets.
[0051]
Next, the raw laminate was heated at a temperature rising rate of 0.1 ° C./min, degreased at a temperature of 500 ° C., and then maintained at a temperature of 1300 ° C. for 2 hours in a reducing atmosphere. Baked.
[0052]
Next, an external electrode was formed on the outer surface of the obtained laminate after sintering by applying a conductive paste containing copper as a conductive component and baking it to obtain a multilayer ceramic capacitor as a sample. .
[0053]
In the manufacture of such a multilayer ceramic capacitor, in the case of a multilayer ceramic capacitor manufactured using a ceramic raw material powder heat-treated at a temperature of 500 ° C. after evaporation and drying, delamination does not occur and desired electrical characteristics are obtained. I was able to get it.
[0054]
On the other hand, in the case of a multilayer ceramic capacitor manufactured using a ceramic raw material powder that has not been heat-treated after evaporation and drying, delamination occurs in the multilayer body after the degreasing process, and the electrical characteristics of the obtained multilayer ceramic capacitor are It was impossible to evaluate.
[0055]
Although the present invention has been described mainly with reference to the method for manufacturing a multilayer ceramic capacitor, the present invention can be equally applied to the manufacture of multilayer ceramic electronic components other than the multilayer ceramic capacitor.
[0056]
【The invention's effect】
As described above, according to the present invention, when the ceramic raw material powder used for manufacturing the multilayer ceramic electronic component contains a metal hydroxide, when the ceramic raw material powder is subjected to X-ray diffraction analysis, The ceramic raw material powder at a temperature applied in the heat treatment for the ceramic raw material powder in which the product peak disappears and an analysis result is obtained in which the formation of a composite other than the metal oxide contained in the metal hydroxide is not confirmed. Since the metal hydroxide is removed from the ceramic raw material powder, the endothermic reaction when H ₂ O is separated from the metal hydroxide does not occur when the raw laminate is degreased. Effectively preventing delamination caused by the stress caused by this endothermic reaction It can be.
[0057]
Therefore, a multilayer ceramic electronic component such as a multilayer ceramic capacitor having desired electrical characteristics can be manufactured with a good yield.
[0058]
In addition, since the temperature applied in the process of heat-treating the ceramic raw material powder containing the metal hydroxide is determined according to the composition of the ceramic raw material powder, a preparatory step for finding such a temperature is performed. If it is carried out only once, the production stage process for mass production of the multilayer ceramic electronic component can be repeated a plurality of times, and the production of the multilayer ceramic electronic component can be advanced efficiently.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a multilayer ceramic capacitor 1 as an example of a multilayer ceramic electronic component manufactured by a manufacturing method according to the present invention.
FIG. 2 is a diagram showing an X-ray diffraction analysis result of a ceramic raw material powder implemented in an experimental example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor 2 Laminate 3 Dielectric ceramic layer 4, 5 Internal electrode 8, 9 External electrode

Claims (6)

Heat treating ceramic raw material powder containing metal hydroxide;
A step of producing a ceramic slurry by mixing the ceramic raw material powder after the heat treatment with a vehicle comprising an organic solvent and a binder;
Forming a ceramic green sheet by forming the ceramic slurry into a sheet; and
Forming a conductor layer for an internal conductor on the ceramic green sheet;
A step of producing a raw laminate by laminating a plurality of the ceramic green sheets;
Degreasing and then firing the raw laminate,
The temperature applied in the step of heat-treating the ceramic raw material powder containing the metal hydroxide is such that when the ceramic raw material powder is subjected to X-ray diffraction analysis, the peak of the metal hydroxide disappears, and the metal hydroxide Set to a temperature applied in the heat treatment of the ceramic raw material powder so as to obtain an analysis result that does not confirm the formation of a composite other than the metal oxide contained in
Manufacturing method of multilayer ceramic electronic component. Heat treating ceramic raw material powder containing metal hydroxide at an appropriate temperature, and then subjecting the heat treated ceramic raw material powder to X-ray diffraction analysis;
In the X-ray diffraction analysis, the ceramic raw material from which an analysis result is obtained in which the peak of the metal hydroxide disappears and the formation of a composite other than the metal oxide contained in the metal hydroxide is not confirmed. Finding a temperature applied in the heat treatment on the powder,
Heat treating the ceramic raw material powder containing the metal hydroxide at a temperature found by the X-ray diffraction analysis;
A step of producing a ceramic slurry by mixing the ceramic raw material powder after the heat treatment with a vehicle comprising an organic solvent and a binder;
Forming a ceramic green sheet by forming the ceramic slurry into a sheet; and
Forming a conductor layer for an internal conductor on the ceramic green sheet;
A step of producing a raw laminate by laminating a plurality of the ceramic green sheets;
Including a step of degreasing and then firing the raw laminate,
Manufacturing method of multilayer ceramic electronic component. The method of manufacturing a multilayer ceramic electronic component according to claim 2, wherein the manufacturing process is repeated a plurality of times after the preparation process is performed once. The metal hydroxide includes Mg (OH) ₂ , Ca (OH) ₂ , La (OH) ₃ , Ce (OH) ₃ , Pr (OH) ₃ , Nd (OH) ₃ , Pm (OH) ₃ , Sm The method for producing a multilayer ceramic electronic component according to claim 1, wherein the method is at least one of (OH) ₃ , Eu (OH) _3, and Gd (OH) ₃ . The method for manufacturing a multilayer ceramic electronic component according to claim 4, wherein the metal hydroxide is Gd (OH) ₃ . In the step of forming a conductor layer for the inner conductor on the ceramic green sheet, the conductor layer for the inner conductor is on each of the plurality of ceramic green sheets, and the raw laminate is produced. The conductive layer for the inner conductor is formed on the outer surface of the fired multilayer body after the step of firing the raw multilayer body, which is formed at a position facing through the ceramic green sheet. The method for manufacturing a multilayer ceramic electronic component according to claim 1, further comprising a step of forming an external electrode so as to be electrically connected to a specific one.

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