JP2007204315A - Method of manufacturing ceramic powder, ceramic powder and laminated ceramic electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing ceramic powder having a surface uniformly and firmly coated with an additive component, the ceramic powder and a laminated ceramic electronic component manufactured using the ceramic powder and having required characteristics. <P>SOLUTION: The surface of the ceramic powder is coated with gel of a metal element-containing material by preparing a liquid mixture formed by mixing a sol of an organic acid complex of a metal element and/or the metal element containing material with a suspension of the ceramic powder and hydrothermally reacting the liquid mixture under a condition of a temperature of >100°C and a pressure of >0.1 MPa. The ceramic powder consists essentially of barium titanate or barium calcium titanate. In the hydrothermal reaction, the temperature is controlled to <300°C and the pressure is controlled to <8.6 MPa. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a ceramic powder whose surface is coated with a metal element-containing substance, which is used for producing a ceramic electronic component, a ceramic powder produced by the production method, and a multilayer ceramic electronic component.

One example of a multilayer ceramic electronic component using a ceramic material is a multilayer ceramic capacitor using a barium titanate (BaTiO ₃ ) -based ceramic material as a dielectric ceramic material.

  In dielectric ceramic materials such as barium titanate, various additives (Mg, Mn, rare earth elements, etc.) are added in order to improve dielectric constant, temperature characteristics, reliability, and the like. This additive must be sufficiently dispersed in the barium titanate main raw material powder, and in particular, a form adhering to the surface of the barium titanate main raw material powder is desirable.

  As a method of coating the surface of the barium titanate powder with the substance to be added (additional component), the barium titanate powder is suspended in the solution of the additional component and heated to deposit the additional component on the surface of the barium titanate. A method has been proposed (see Patent Document 1).

  However, in the above conventional method, it is difficult to uniformly deposit an oxide of a rare earth element on the surface of barium titanate, that is, to form a uniform coating film of additive components on the surface of barium titanate, Further, there is a problem that the formed coating film is easily peeled off.

  For example, in order to mix the barium titanate powder coated with the additive component by the conventional method with a binder, when a strong shear force is applied by a medium stirring mill or the like, the coating layer is peeled off relatively easily, There is a problem that it becomes impossible to obtain a product (multilayer ceramic electronic component) having the intended characteristics.

In addition, a method has been proposed in which the barium titanate powder coated with the additive components is dried and the adhesion is increased by heat treatment. There arises a new problem that it becomes impossible to obtain the barium titanate powder dispersed in.
Japanese Unexamined Patent Publication No. 2000-281341

  The present invention solves the above-mentioned problems, and is produced using a method for producing a ceramic powder whose surface is uniformly and firmly coated with an additive component, a ceramic powder produced by the production method, and the ceramic powder. Another object of the present invention is to provide a multilayer ceramic electronic component having desired characteristics.

In order to solve the above problems, the method for producing a ceramic powder according to claim 1 is a method for producing a ceramic powder whose surface is coated with a gel of a metal element-containing substance,
A first step of preparing a mixed solution in which a suspension of ceramic powder is mixed with an organic acid complex of a metal element and / or a sol of a metal element-containing substance;
Second, the surface of the ceramic powder is coated with the gel of the metal element-containing material by causing a hydrothermal reaction to be performed on the mixed liquid under conditions of a temperature of over 100 ° C. and a pressure of over 0.1 MPa. It is characterized by comprising the following processes.

  According to a second aspect of the present invention, there is provided a method for producing a ceramic powder comprising, after the second step of performing the hydrothermal reaction of the first aspect, further comprising a ceramic powder having a surface coated with the metal element-containing substance gel. It is characterized by including a third step of drying.

The method for producing a ceramic powder according to claim 3 is the structure of the invention according to claim 1 or 2,
(a) the main component of the ceramic powder is barium titanate or barium calcium titanate,
(b) the temperature is less than 300 ° C,
(c) The pressure is less than 8.6 MPa.

  According to a fourth aspect of the present invention, there is provided a method for producing a ceramic powder according to any one of the first to third aspects, wherein the organic acid forming the organic acid complex of the metal element is acetic acid, citric acid, succinic acid, lactic acid. , At least one selected from the group consisting of malic acid, malonic acid, tartaric acid and glycolic acid.

  The method for producing a ceramic powder according to claim 5 is characterized in that the organic acid supply source is an ammonium salt.

  According to a sixth aspect of the present invention, there is provided a method for producing a ceramic powder according to any one of the first to fifth aspects of the present invention, wherein the colloidal particles forming the sol of the metal element-containing substance are an oxide of the metal element, a hydroxide And at least one selected from the group consisting of a basic carbonate and a carbonate.

Moreover, the manufacturing method of the ceramic powder of Claim 7 WHEREIN: In the structure of the invention in any one of Claims 1-6,
The metal element is selected from the group consisting of lanthanoid elements, Y, Ba, Ca, Sr, Mg, Ti, Zr, Hf, Cu, V, Nb, Ta, Mn, Ni, Cr, Co, Zn, Si, and Sb. It is characterized by being at least one kind.

  The ceramic powder according to claim 8 is produced by the method for producing ceramic powder according to claim 2, and the surface is covered with a layer formed by drying a gel of a metal element-containing substance. Yes.

The multilayer ceramic electronic component of claim 9 is
A multilayer ceramic electronic component having a structure in which internal electrodes are laminated via a ceramic layer in a dielectric ceramic,
A ceramic powder produced by the production method according to any one of claims 1 to 7 is used as the ceramic material for the dielectric ceramic.

The multilayer ceramic electronic component of claim 10 is
A multilayer ceramic electronic component having a structure in which internal electrodes are laminated via a ceramic layer in a dielectric ceramic,
As a conductive material for the internal electrode, a conductive material containing a ceramic powder manufactured by the manufacturing method according to any one of claims 1 to 7 is used.

The multilayer ceramic electronic component of claim 11
A multilayer ceramic electronic component having a structure in which internal electrodes are laminated via a ceramic layer in a dielectric ceramic,
As the ceramic material for the dielectric ceramic, ceramic powder produced by the production method according to claim 1 is used,
As a conductive material for the internal electrode, a conductive material containing a ceramic powder manufactured by the manufacturing method according to any one of claims 1 to 7 is used.

  In the method for producing ceramic powder according to claim 1, a mixed solution is prepared by mixing a suspension of ceramic powder with an organic acid complex of a metal element and / or a sol of a metal element-containing substance. The surface of the ceramic powder is coated with the gel of the metal element-containing substance by hydrothermal reaction under conditions of over 100 ° C. and pressure: over 0.1 MPa. The gel of the contained substance can be coated uniformly and firmly. Therefore, by applying the present invention, when it is desired to coat the surface of the ceramic powder with the additive component, the surface of the ceramic powder is homogeneously and firmly coated with the substance (gel) containing the additive component. It becomes possible to provide a ceramic powder in which the layers are difficult to peel off.

  That is, when an additive component such as a metal element is coated on the surface of the ceramic powder, a hydrothermal reaction (heating and under pressure) is used to convert the metal organic acid complex or sol to a ceramic powder such as a barium titanate powder. By making the gel on the surface and reacting a part thereof with the surface of the ceramic powder, a coating layer having a strong adhesive force can be formed uniformly on the surface of the ceramic powder. Moreover, since it can implement in a wet reaction, it can suppress that ceramic powders, such as a coated barium titanate powder, condense, and can obtain the homogeneous ceramic powder rich in dispersibility.

  In the invention of the present application, the above-mentioned effect can be obtained because it dissolves with the coating component in the vicinity of the surface of the ceramic powder such as barium titanate under the condition that the hydrothermal reaction occurs sufficiently. Since the reprecipitation reaction occurs, the ceramic powder such as barium titanate is reprecipitated in a state in which the coating component element is incorporated, and thus it is considered that a strong and uniform coating layer is formed.

  In addition, when the surface of ceramic powder such as barium titanate is coated with an oxide of another metal element or its precursor, the coated ceramic powder such as barium titanate is used as the dielectric material of the multilayer ceramic capacitor. By using as a case, it is possible to prevent the occurrence of partial segregation and uneven firing by allowing the reaction during firing to proceed uniformly, and when the ceramic layer that becomes the dielectric layer is thinned In addition, a multilayer ceramic capacitor having high reliability can be obtained.

Further, as in the ceramic powder manufacturing method of claim 2, after the second step of performing the hydrothermal reaction of claim 1, the surface is further coated with a gel of the metal element-containing substance. When the third step of drying the powder is provided, it becomes possible to obtain a dry ceramic powder having a coating layer made of a metal powder-containing substance on the surface.
Then, it becomes possible to produce a ceramic green sheet through, for example, a step of mixing this dry ceramic powder with a binder, etc., so that a multilayer ceramic electronic component having desired characteristics can be efficiently manufactured. Become.

  Further, as in the method for producing a ceramic powder according to claim 3, in the configuration of the invention according to claim 1 or 2, (a) the main component of the ceramic powder is barium titanate or barium calcium titanate, and (b) the temperature is By setting the temperature to less than 300 ° C. and (c) the pressure to less than 8.6 MPa, it is possible to reliably coat the surface of the ceramic powder with the metal element-containing substance or the gel thereof. Can be effectively realized.

  Moreover, like the manufacturing method of the ceramic powder of Claim 4, in the structure of any one of Claims 1-3, the organic acid which forms the organic acid complex of a metal element is acetic acid, a citric acid, succinic acid, By using an organic acid complex that is at least one selected from the group consisting of lactic acid, malic acid, malonic acid, tartaric acid, and glycolic acid, the surface of the ceramic powder is efficiently coated with the metal element-containing substance or its gel. It becomes possible to make the present invention effective.

  In addition, when an ammonium salt is used as the organic acid supply source as in the ceramic powder manufacturing method of claim 5, it is possible to effectively form an organic acid complex of a metal element. The invention can be further improved.

  Further, as in the method for producing ceramic powder according to claim 6, in the configuration of any one of claims 1 to 5, the colloidal particles forming the sol of the metal element-containing substance are metal element oxides, hydroxides By making at least one selected from the group consisting of a material, a basic carbonate, and a carbonate, the surface of the ceramic powder can be uniformly and firmly coated with the metal element-containing material or its gel. Thus, the present invention can be effectively presented.

  Moreover, like the manufacturing method of the ceramic powder of Claim 7, in the structure of any one of Claims 1-6, a metal element is a lanthanoid element, Y, Ba, Ca, Sr, Mg, Ti, Zr, By using at least one selected from the group consisting of Hf, Cu, V, Nb, Ta, Mn, Ni, Cr, Co, Zn, Si, and Sb, various metal element-containing materials or gels thereof can be used for the ceramic powder. It becomes possible to coat the surface uniformly and firmly. Therefore, according to the present invention, it becomes possible to uniformly apply various additives to the surface of the ceramic powder. By using the ceramic powder, it is possible to efficiently produce a multilayer ceramic electronic component having desired characteristics. It becomes possible to do.

  The ceramic powder according to claim 8 is a ceramic powder produced by the method for producing ceramic powder according to claim 2, and the surface is coated with a layer formed by drying a gel of a metal element-containing substance. Since the coating layer made of the metal element-containing material is homogeneous and firmly attached to the surface of the ceramic powder, for example, when mixing with a binder, a strong shearing force was applied by a medium stirring mill or the like. Even in this case, the coating layer is difficult to peel off. As a result, by using the ceramic powder of the present invention, it is possible to reliably manufacture a product (multilayer ceramic electronic component) having intended characteristics.

  The multilayer ceramic electronic component of claim 9 is a ceramic material for a dielectric ceramic in a multilayer ceramic electronic component having a structure in which an internal electrode is laminated via a ceramic layer in a dielectric ceramic. Since the ceramic powder with the surface coated with the metal element-containing substance or the gel produced by the production method according to any one of 7 to 7 is used, a uniform reaction can be advanced in the firing process. Since a dielectric ceramic with few defects is formed after firing, it is possible to provide a multilayer ceramic electronic component having desired characteristics and high reliability.

  The multilayer ceramic electronic component of claim 10 is a multilayer ceramic electronic component having a structure in which an internal electrode is laminated via a ceramic layer in a dielectric ceramic, wherein the multilayer ceramic electronic component is a conductive material for the internal electrode. Since the conductive material containing the ceramic powder manufactured by the manufacturing method in any one of 1-7 is used, the coating layer works as a sintering suppression layer, and the conductive component (for example, constituting the conductive paste up to a high temperature) By staying between (Ni particles), for example, it is possible to suppress the grain growth of conductive components such as Ni particles, and to improve the coverage of the internal electrode after sintering, and to provide a multilayer ceramic electronic component with good characteristics Can be manufactured efficiently.

  The multilayer ceramic electronic component of claim 11 is a multilayer ceramic electronic component having a structure in which an internal electrode is laminated through a ceramic layer in a dielectric ceramic, and is claimed as a ceramic material for the dielectric ceramic. While the ceramic powder manufactured by the manufacturing method in any one of Claims 1-7 is used, it manufactured by the manufacturing method in any one of Claims 1-7 as an electroconductive material for internal electrodes. Conductive material containing ceramic powder is used, so it has the intended characteristics and excellent adhesion between the internal electrode and the ceramic layer, and it is difficult for delamination and cracking between the internal electrode and the ceramic layer. It becomes possible to reliably manufacture a highly reliable multilayer ceramic electronic component.

That is, when the conductive material containing the ceramic powder manufactured by the manufacturing method according to any one of claims 1 to 7 is used as the conductive material for the internal electrode, in particular, the ceramic constituting the dielectric layer and When an internal electrode is formed using a conductive paste containing the same ceramic raw material powder, the coating layer works as a sintering suppression layer for the ceramic powder in the conductive paste, and the conductive paste is constructed up to a high temperature. By staying between the conductive components (for example, Ni particles), it is possible to suppress the grain growth of the conductive components such as Ni particles and improve the coverage of the internal electrode after sintering.
The ceramic powder blended in the conductive material for the internal electrode and the ceramic powder for the dielectric ceramic are desirably the same or similar in composition, but even if the composition is different, It is possible to obtain the basic effect of controlling the sintering behavior.

  The features of the present invention will be described in more detail below with reference to examples of the present invention.

  In Example 1, the surface of the barium titanate powder constituting the dielectric ceramic layer of the multilayer ceramic capacitor is coated with a substance containing the additive elements metal elements Ba, Mg, Mn, Si, and Dy, whereby the surface Barium titanate powder coated with a metal element-containing substance, which is an additive component, was produced. Hereinafter, the manufacturing method will be described.

  (1) 100 g of barium titanate powder was put together with 1400 g of PSZ beads having a diameter of 1 mm into a resin pot with a capacity of 1 L, and 400 ml of pure water was added and crushed in a ball mill for 12 hours.

  (2) Then, 7.2 g Ba carbonate sol, 3.5 g Mg citrate complex, 0.85 g Mn citrate complex, 0.86 g Si oxide sol, and 18.6 g Dy citrate complex were added. The mixture was further mixed with a ball mill for 1 hour to prepare a slurry.

  (3) Thereafter, 200 ml of this slurry is put into a polytetrafluoroethylene container and subjected to a hydrothermal reaction in an autoclave under conditions of a temperature of 200 ° C., a pressure of 1.5 MPa, and a time of 4 hours to obtain the surface of the barium titanate powder. In addition, a gel of a substance (oxide, hydroxide, basic carbonate, carbonate, etc.) containing a metal element (Ba, Mg, Mn, Si, Dy in this Example 1) is generated, and titanic acid is generated by the gel. The surface of barium powder was coated.

  (4) After the hydrothermal reaction is completed, the slurry is dehydrated with Nutsche, further washed with 100 ml of pure water, and then dried in an oven at 140 ° C., so that the surface is a metallic element (in this Example 1, Ba). , Mg, Mn, Si, Dy), barium titanate powder coated with an oxide, carbonate or the like was obtained.

  As described above, to the barium titanate powder, a sol containing a metal element-containing substance as an additional component and an organic acid complex are added so as to have a predetermined dielectric ceramic raw material composition, and the slurry is subjected to water under appropriate conditions. By performing the heat treatment, it is possible to obtain a barium titanate powder in which a strong coating layer made of a substance containing an additive component element is formed on the surface of the barium titanate powder.

  The coating layer on the surface of the barium titanate powder of Example 1 is also used in the mixing and milling with the binder performed in the process of producing the ceramic green sheet using the ceramic green sheet powder. It is difficult to peel off from the surface of the film, and a uniform coating layer is maintained. Therefore, even in the firing step when manufacturing the multilayer ceramic capacitor, it is possible to allow a uniform reaction to proceed, and a dielectric ceramic with few defects after firing can be obtained. As a result, a multilayer ceramic capacitor having desired characteristics and high reliability (long life) can be obtained.

  (1) 100 g of barium titanate powder was put together with 1400 g of PSZ beads having a diameter of 1 mm into a resin pot with a capacity of 1 L, and 400 ml of pure water was added and crushed in a ball mill for 12 hours.

  (2) Then, 14.4 g of Ba carbonate sol, 6.1 g of Ca carbonate sol, 19.1 g of Zr oxide sol, 0.85 g of Mn citrate complex, 1.0 g of Ni hydroxide sol Then, 0.86 g of Si oxide sol and 4.6 g of Dy citrate complex were added, and further mixed for 1 hour by a ball mill to prepare a slurry.

  (3) Thereafter, 200 ml of this slurry was put into a polytetrafluoroethylene container and subjected to hydrothermal reaction in an autoclave under conditions of a temperature of 250 ° C., a pressure of 4.0 MPa, and a time of 4 hours, and the surface of the barium titanate powder. In addition, a gel containing a metal element (Ba, Ca, Zr, Mn, Ni, Si, Dy in Example 2) was formed, and the surface of the barium titanate powder was covered with the gel.

  (4) After the hydrothermal reaction is completed, the slurry is dehydrated with Nutsche, further washed with 100 ml of pure water, and then dried in an oven at 140 ° C., so that the surface is a metallic element (in this Example 2, Ba , Ca, Zr, Mn, Ni, Si, Dy), barium titanate powder coated with an oxide, carbonate or the like.

  As in Example 2, when a metal element-containing substance different from Example 1 is used as an additive component and a hydrothermal reaction is performed under conditions different from Example 1, the same as in Example 1 above. In addition, it was possible to obtain a barium titanate powder in which a strong coating layer made of a substance containing an additive component element was formed on the surface of the barium titanate powder.

  The coating layer on the surface of the barium titanate powder is also difficult to peel off from the surface of the barium titanate powder during mixing with the binder or milling, and a uniform coating layer is maintained. Therefore, even in the firing step when manufacturing the multilayer ceramic capacitor, a uniform reaction can be advanced, and a dielectric ceramic with few defects after firing can be obtained. As a result, a multilayer ceramic capacitor having desired characteristics and high reliability (long life) can be obtained.

  (1) 100 g of barium titanate powder was put together with 1400 g of PSZ beads having a diameter of 1 mm into a resin pot with a capacity of 1 L, and 400 ml of pure water was added and crushed in a ball mill for 12 hours.

  (2) Then, 27.9 g of Dy citrate complex was added and further mixed for 1 hour by a ball mill to prepare a slurry.

  (3) Thereafter, 200 ml of this slurry is put into a polytetrafluoroethylene container and subjected to a hydrothermal reaction in an autoclave under conditions of a temperature of 200 ° C., a pressure of 1.5 MPa, and a time of 4 hours to obtain the surface of the barium titanate powder. Then, a gel of a substance containing a metal element (Dy in this Example 3) was generated, and the surface of the barium titanate powder was covered with the gel.

  (4) After the hydrothermal reaction is completed, the slurry is dehydrated with Nutsche, further washed with 100 ml of pure water, and then dried in an oven at 140 ° C., so that the surface is a metal element (in this example, Dy Barium titanate powder coated with oxide, carbonate, etc.).

  Like Example 3, a metal element-containing substance different from Examples 1 and 2, that is, Dy, which is a kind of rare earth element having a sintering inhibiting effect, was added in the form of an organic acid complex. In the case where hydrothermal reaction is performed under different conditions, barium titanate in which a strong coating layer made of a substance containing an additive component element is formed on the surface of the barium titanate powder as in the case of Example 1 above. A powder could be obtained.

  The coating layer on the surface of the barium titanate powder is also difficult to peel off from the surface of the barium titanate powder during mixing with the binder or milling, and a uniform coating layer is maintained. Therefore, even in the firing step when manufacturing the multilayer ceramic capacitor, a uniform reaction can be advanced, and a dielectric ceramic with few defects after firing can be obtained. As a result, a multilayer ceramic capacitor having desired characteristics and high reliability (long life) can be obtained.

[Comparative Example 1]
(1) 100 g of barium titanate powder was put together with 1400 g of PSZ beads having a diameter of 1 mm into a resin pot with a capacity of 1 L, and 400 ml of pure water was added and crushed in a ball mill for 12 hours.

  (2) Then, 7.2 g Ba carbonate sol, 3.5 g Mg citrate complex, 0.85 g Mn citrate complex, 0.86 g Si oxide sol, and 18.6 g Dy citrate complex were added. The mixture was further mixed with a ball mill for 1 hour to prepare a slurry.

  (3) Thereafter, 200 ml of this slurry was placed in a glass flask and heated and refluxed with an electric heater at a temperature of 100 ° C. and a pressure of 0.1 MPa for 4 hours.

  (4) Then, the slurry after the heating and refluxing treatment was dehydrated with Nutsche, further washed with 100 ml of pure water, and then dried at 140 ° C. in an oven.

  As in Comparative Example 1, the component treated at 100 ° C. and normal pressure did not sufficiently fix the added component on the surface of the barium titanate, and part of the component was eluted when washed with pure water. A coating layer could not be formed.

[Comparative Example 2]
(1) 100 g of barium titanate powder was put together with 1400 g of PSZ beads having a diameter of 1 mm into a resin pot with a capacity of 1 L, and 400 ml of pure water was added and crushed in a ball mill for 12 hours.

(2) Then, 12.3 g of 1 mol / kg Dy (NO ₃ ) ₃ aqueous solution was added and further mixed for 1 hour by a ball mill, and then aqueous ammonia (28%) was added to adjust the pH to 9.0.

  (3) Next, the slurry was dehydrated with Nutsche, further washed with 400 ml of pure water, and then dried in an oven at 140 ° C.

  In the case of the method of Comparative Example 2, a Dy compound coating layer can be formed on the surface of the barium titanate powder as in Example 3 above, but the coating layer and the surface of the barium titanate powder The coating layer was peeled off during the milling process. For this reason, for example, in the firing process in the case of manufacturing a multilayer ceramic capacitor, it becomes impossible to make a uniform reaction, and it becomes impossible to obtain a multilayer ceramic capacitor having desired characteristics and high reliability. The comparative example 2 corresponds to the prior art of the above-mentioned Patent Document 1.

(1) 100 g of barium calcium titanate ((Ba _0.96 , Ca _0.04 ) TiO ₃ ) powder is put into a resin pot with a capacity of 1 L together with 1400 g of PSZ beads having a diameter of 1 mm, and 400 ml of pure water is added for 12 hours in a ball mill. It was crushed.

  (2) Then, 7.2 g Ba carbonate sol, 3.5 g Mg citrate complex, 0.85 g Mn citrate complex, 0.86 g Si oxide sol, and 18.6 g Dy citrate complex were added. The mixture was further mixed with a ball mill for 1 hour to prepare a slurry.

  (3) Thereafter, 200 ml of this slurry is put into a polytetrafluoroethylene container, and subjected to a hydrothermal reaction in an autoclave at a temperature of 200 ° C., a pressure of 1.5 MPa, and a time of 4 hours to obtain a barium calcium titanate powder. A gel of a substance containing a metal element (Ba, Mg, Mn, Si, Dy in Example 4) was generated on the surface, and the surface of the barium calcium titanate powder was covered with the gel.

  (4) After the hydrothermal reaction is completed, the slurry is dehydrated with Nutsche, further washed with 100 ml of pure water, and then dried in an oven at 140 ° C., so that the surface is a metallic element (in this Example 4, Ba , Mg, Mn, Si, Dy), barium calcium titanate powder coated with an oxide, carbonate or the like of a substance containing the material was obtained.

  As in Example 4, when a barium calcium titanate powder was used instead of the barium titanate powder of Example 1, a ceramic powder (barium calcium titanate powder having a uniform coating layer formed on the surface) )

  The coating layer on the surface of the barium calcium titanate powder is also difficult to peel off from the surface of the barium calcium titanate powder during mixing with the binder or milling, and a uniform coating layer is maintained. Therefore, even in the firing step when manufacturing the multilayer ceramic capacitor, a uniform reaction can be advanced, and a dielectric ceramic with few defects after firing can be obtained. As a result, a multilayer ceramic capacitor having desired characteristics and high reliability (long life) can be obtained.

  Table 1 shows a list of the compositions and manufacturing conditions of the samples of the above examples and comparative examples. The composition indicates the amount of each additive element (metal element) in moles with respect to 100 mol of barium titanate (100 mol of barium calcium titanate in Example 4).

Moreover, the ceramic powder obtained by the method of the said Example and the comparative example was milled, and the magnitude | size of the adhesive force of a coating layer was investigated.
In comparing the adhesion of the coating layers of the ceramic powders produced in the examples and comparative examples, TEM (transmission electron microscope) -EDX (energy dispersive X-ray fluorescence analysis) was used.
That is, as shown in FIGS. 1 (a) and 1 (b), the concentration of the coating element (metal element) at the center part 1a and the end part 1b of the ceramic powder (particles) 1 after milling is determined by TEM (transmission electron microscope). The presence or absence of a coating layer on the surface of the ceramic powder was confirmed by comparison using -EDX (energy dispersive X-ray fluorescence analysis). The results are shown in Table 2. In Table 2, “ND” indicates that the element is not detected by the above analysis.
1A is a diagram schematically showing a sample of an embodiment of the present invention in which a sufficient coating layer 2 is present on the surface of the ceramic powder (particles) 1, and FIG. It is a figure which shows typically the sample of the comparative example which does not exist on the surface of the ceramic powder.

  In Table 2, the ratio of remaining coating layer is high when the coating element concentration at the particle edge is high, and the ratio of remaining coating layer is low when the coating element concentration at the particle edge is low. Is shown.

  In the case of the sample of the example, since the adhesion force of the coating layer to the surface of the ceramic powder is large and strong, the coating layer remains even after milling as shown in FIG. As shown in FIG. 1B, it was confirmed that the coating layer peeled off and did not remain on the surface of the ceramic powder, or even if it remained, the amount was small. In Table 2, those that are “ND” both before and after milling indicate that the element was tried to be coated but was not confirmed by the above analysis. .

  In Examples 1 to 4, the hydrothermal reaction was performed at a temperature of 200 ° C. (Examples 1, 3, 4), 250 ° C. (Example 2), a pressure of 1.5 MPa (Examples 1, 3, 4), Although the case where it was made to perform on condition of 4.0MPa (Example 2) was demonstrated as an example, in the conditions of temperature less than 300 degreeC and pressure less than 8.6MPa, it is the same as the case of said Examples 1-4. In addition, it has been experimentally confirmed that the surface of the ceramic powder can be efficiently coated with the metal element-containing substance or its gel.

  On the other hand, when the temperature condition of the hydrothermal reaction was 300 ° C. or more and the pressure condition was 8.6 MPa or more, the effect of covering the surface of the ceramic powder with the metal element-containing substance or its gel was slightly reduced.

  Therefore, in the method for producing a ceramic powder of the present invention, in order to ensure the effects, it is desirable that the hydrothermal reaction conditions are a temperature: less than 300 ° C. and a pressure: less than 8.6 MPa.

  Using the ceramic powder produced by the method of Example 1 and the ceramic powder produced by the method of Comparative Example 1, a multilayer ceramic capacitor having a structure as shown in FIG. 2 was produced, and the reliability was compared. .

The multilayer ceramic capacitor shown in FIG. 2 includes a plurality of internal electrodes 12 a and 12 b laminated and disposed in a ceramic element (electronic component element) 11 via a ceramic layer 13. The opposing internal electrodes 12a, 12b are alternately drawn out to the opposite end faces 14a, 14b of the ceramic element 11 and connected to a pair of external electrodes 15a, 15b formed on both end faces of the ceramic element 11. is doing.
The manufacturing method of this multilayer ceramic capacitor is as follows.
(1) First, the ceramic powder produced by the method of Example 1 and the ceramic powder produced by the method of Comparative Example 1 were prepared.
(2) A polyvinyl butyral binder and an ethanol organic solvent were added to each ceramic powder and wet mixed by a ball mill to prepare a ceramic slurry.
(3) The ceramic slurry was formed into a sheet by a doctor blade method to obtain a short green sheet having a thickness of 5 μm.
(4) On this ceramic green sheet, the electroconductive paste which has Ni powder as a main component was printed, and the electroconductive paste film (internal electrode pattern) for comprising an internal electrode was formed.
(5) A plurality of ceramic green sheets were laminated so that the side from which the above-mentioned conductive paste film was drawn was staggered to obtain a laminate.
(6) The laminate was heated to a temperature of 350 ° C. at a N ₂ atmosphere, after burning a binder, oxygen partial pressure 10 ^-9 to 10 ^-12 MPa of H ₂ -N ₂ -H ₂ O gas Was fired at a temperature of 1150 to 1250 ° C. in a reducing atmosphere.
(7) A silver paste containing B ₂ O ₃ —SiO ₂ —BaO-based glass frit is applied to both end faces of the fired laminate, and baked at a temperature of 600 ° C. in an N ₂ atmosphere. Connected external electrodes were formed.

  The outer dimensions of the multilayer ceramic capacitor thus obtained are 3.2 mm in width, 1.6 mm in length, and 1.2 mm in thickness. The thickness of the dielectric ceramic layer interposed between the internal electrodes is as follows. It was 3.0 μm.

The number of effective ceramic layers (dielectric layers) was 100, and the area of the counter electrode per layer was 3.0 × 10 ⁻⁶ m ² .

A high-temperature load test (150 ° C., 60 V applied, when the resistance dropped to 10 ⁵ Ω or less was regarded as a failure) was performed on each of the 10 samples obtained, and the average life time (MTTF) was compared.

  The average life time (MTTF) is 17 hours for the multilayer ceramic capacitor using the ceramic powder of Example 1, and 8 hours for the multilayer ceramic capacitor using the ceramic powder of Comparative Example 1. It was confirmed that the multilayer ceramic capacitor using the ceramic powder has high reliability.

  In addition, a dielectric ceramic layer is formed using the ceramic powder produced in Example 3, and the same method as in Example 5 is used using the conductive paste to which the ceramic powder produced in Example 3 is added. A multilayer ceramic capacitor was manufactured.

  As in Example 6, when the same ceramic powder as the ceramic powder constituting the dielectric ceramic layer is blended with the conductive paste for forming the internal electrode, the sintering of the Ni powder is suppressed to a high temperature in the firing process. It is possible to improve the internal electrode coverage and prevent structural deficiencies due to mismatch in shrinkage behavior with the ceramic layer, and to obtain a multilayer ceramic capacitor with desired characteristics and high reliability. Is possible.

  In Example 6 described above, the same ceramic powder as the ceramic powder constituting the dielectric ceramic layer is added to the conductive paste for forming the internal electrode, but regardless of the ceramic powder constituting the dielectric ceramic layer. The ceramic powder having the requirements of the present invention can be added only to the conductive paste for forming the internal electrodes.

  In the case of the multilayer ceramic capacitor of Example 6, the same effects as in the case of the multilayer ceramic capacitor of Example 5 can be obtained in other respects.

  In Examples 5 and 6 described above, the multilayer ceramic capacitor has been described as an example. However, the ceramic powder of the present invention is not limited to the multilayer ceramic capacitor, and various multilayer ceramic electronic parts such as multilayer LC composite parts and multilayer substrates can be manufactured. Can be used.

  The invention of the present application is not limited to the above embodiment in other points as well. Specific conditions for performing the hydrothermal reaction, the type of organic acid forming the organic acid complex of the metal element, and the metal element Various applications and modifications can be made within the scope of the invention with respect to the type of colloidal particles forming the sol of the contained substance, the type of metal element, and the like.

As described above, according to the present invention, it is possible to efficiently produce a ceramic powder whose surface is uniformly and firmly coated with an additive component, and by using the obtained ceramic powder, reliability can be improved. It becomes possible to obtain a multilayer ceramic electronic component such as a high multilayer ceramic capacitor.
Therefore, the present invention can be widely applied in the fields of ceramic powder manufacturing, manufacturing technology of multilayer ceramic electronic parts such as multilayer ceramic capacitors manufactured using ceramic powder containing additive components, and the like.

(a) is a figure which shows typically the sample of the Example in which sufficient coating layer exists in the surface of ceramic powder, (b) is a comparative example in which the coating layer does not exist in the surface of ceramic powder. It is a figure which shows a sample typically. It is a figure which shows the laminated ceramic capacitor manufactured using the ceramic powder concerning the Example of this invention.

Explanation of symbols

1 Ceramic powder (particles)
DESCRIPTION OF SYMBOLS 1a Center part 1b End part 2 Coating layer 11 Ceramic element (electronic component element)
12a, 12b Internal electrode 13 Ceramic layer 14a, 14b End face 15a, 15 External electrode

Claims (11)

A first step of preparing a mixed solution in which a suspension of ceramic powder is mixed with an organic acid complex of a metal element and / or a sol of a metal element-containing substance;
Second, the surface of the ceramic powder is coated with the gel of the metal element-containing material by causing a hydrothermal reaction to be performed on the mixed liquid under conditions of a temperature of over 100 ° C. and a pressure of over 0.1 MPa. A method for producing a ceramic powder having a surface coated with a gel of a metal element-containing substance. 3. The method according to claim 1, further comprising a third step of drying the ceramic powder whose surface is coated with the metal element-containing substance gel after the second step of performing the hydrothermal reaction. A method for producing ceramic powder. (a) the main component of the ceramic powder is barium titanate or barium calcium titanate,
(b) the temperature is less than 300 ° C,
(c) The method according to claim 1 or 2, wherein the pressure is less than 8.6 MPa.   The organic acid that forms the organic acid complex of the metal element is at least one selected from the group consisting of acetic acid, citric acid, succinic acid, lactic acid, malic acid, malonic acid, tartaric acid, and glycolic acid. The manufacturing method of the ceramic powder in any one of Claims 1-3.   The method for producing a ceramic powder according to claim 4, wherein the organic acid source is an ammonium salt.   The colloidal particles forming the sol of the metal element-containing substance are at least one selected from the group consisting of oxides, hydroxides, basic carbonates and carbonates of the metal elements. The manufacturing method of the ceramic powder in any one of claim | item 1 -5.   The metal element is selected from the group consisting of lanthanoid elements, Y, Ba, Ca, Sr, Mg, Ti, Zr, Hf, Cu, V, Nb, Ta, Mn, Ni, Cr, Co, Zn, Si, and Sb. The method for producing a ceramic powder according to claim 1, wherein the method is at least one kind.   A ceramic powder produced by the method for producing a ceramic powder according to claim 2, wherein the surface is coated with a layer formed by drying a gel of a metal element-containing substance. A multilayer ceramic electronic component having a structure in which internal electrodes are laminated via a ceramic layer in a dielectric ceramic,
A ceramic powder produced by the production method according to any one of claims 1 to 7 is used as the ceramic material for the dielectric ceramic. A multilayer ceramic electronic component having a structure in which internal electrodes are laminated via a ceramic layer in a dielectric ceramic,
A multilayer ceramic electronic component, wherein a conductive material containing a ceramic powder produced by the production method according to claim 1 is used as the conductive material for the internal electrode. A multilayer ceramic electronic component having a structure in which internal electrodes are laminated via a ceramic layer in a dielectric ceramic,
As the ceramic material for the dielectric ceramic, ceramic powder produced by the production method according to claim 1 is used,
A multilayer ceramic electronic component, wherein a conductive material containing a ceramic powder produced by the production method according to claim 1 is used as the conductive material for the internal electrode.

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