JP5066873B2 - Green sheet, ceramic electronic component using the same, and manufacturing method thereof - Google Patents

Description

  The present invention relates to a green sheet, a ceramic electronic component using the green sheet, and a method for manufacturing the same, and more particularly to a green sheet using a perovskite compound powder.

  A conventional green sheet and a method for manufacturing a ceramic electronic component using the same will be described. FIG. 8 is a step diagram showing a method for manufacturing a green sheet using barium titanate and a ceramic electronic component using the green sheet.

  First, barium carbonate and titanium oxide are prepared (FIGS. 8A and 8B), and a slurry is prepared by adding these barium carbonate and titanium oxide, a binder, a plasticizer, etc. in a solvent (FIG. 8C), and applied onto the base film. Thus, the sheet is molded to produce a green sheet (FIG. 8D). The green sheet and the electrode layer are stacked, removed, calcined (FIG. 8E), and then fired to react barium carbonate and titanium oxide to produce a barium titanate ceramic electronic component (FIG. 8F). .

  This manufacturing method is generally called a reactive sintering method. In this reactive sintering method, calcining and firing are performed collectively or divided after green sheet production, so that there is no occurrence of necking due to calcining between particles before green sheet production. Is less uneven. Therefore, there is an advantage that it is easy to form a sheet uniformly when producing a green sheet.

Patent Document 1 is known as prior art document information related to the present invention.
JP 2002-193663 A

  On the other hand, in the case of the reaction sintering method described above, the reaction between barium carbonate and titanium oxide occurs during the firing of the green sheet, and at that time, carbon dioxide gas is also generated. The generation of carbon dioxide gas causes expansion of the green sheet, so that the obtained ceramic has poor sinterability, and as a result, there is a problem that reliability is lowered.

  Accordingly, an object of the present invention is to provide a green sheet with improved reliability, a ceramic electronic component using the green sheet, and a manufacturing method thereof.

In order to achieve this object, the present invention is a green sheet using Ba ₂ TiO ₄ containing at least Ba and Ti, wherein the number of moles of Ba is larger than the number of moles of Ti, and TiO ₂ containing at least Ti. Thus, the Ba ₂ TiO ₄ and the TiO ₂ are both in an anisotropic shape to form a green sheet.

  According to the green sheet of the present invention, since there is no expansion of the green sheet due to gas generation, the sinterability of the obtained ceramic can be improved, and as a result, the reliability can be improved. Moreover, a dielectric constant can also be improved by improving sinterability.

  Hereinafter, a green sheet of the present invention, a ceramic electronic component using the green sheet, and a manufacturing method thereof will be described with reference to an embodiment and drawings.

Incidentally, it is described with reference to barium titanate (BaTiO ₃₎ as a perovskite compound (ABO _3). Here, the element A is Ba and the element B is Ti.

  FIG. 1 is a step diagram showing a method of manufacturing a ceramic electronic component using the green sheet of the present invention, and FIG. 2 is a conceptual diagram of the green sheet in the manufacturing process.

First, in order to produce dibarium titanate (Ba ₂ TiO ₄ ) as a compound α composed of at least element A and element B, and the number of moles of element A being larger than the number of moles of element B, barium carbonate (BaCO ₃ ) Titanium oxide (TiO ₂ ) is mixed and calcined (FIG. 1A). At this time, by setting the calcining temperature high, for example, about 1000 ° C., impurities remaining in dibarium titanate, that is, the remaining amount of barium carbonate can be reduced. Even if particle growth due to inter-particle sintering occurs by raising the calcination temperature, it is possible to reduce the dibarium titanate particles by pulverization in the immediately subsequent step. This pulverization is performed on the dibarium titanate particles, and the pulverization here does not adversely affect the crystallinity of the finally obtained barium titanate.

  Next, as shown in FIG. 2A, the prepared compound α, dibarium titanate 1, and titanium oxide 2 as compound β containing at least element B are dispersed in a solvent together with a binder, a plasticizer, and the like. Then, a slurry is prepared, and this is applied onto a base film and formed into a sheet, thereby producing a green sheet 3 shown in FIG. 2B (FIG. 1B).

  Next, the green sheet 3 is debindered and calcined to obtain barium titanate (FIG. 1C). Here, the binder is removed and calcined in the state of the green sheet, but since the slurry made of dibarium titanate and titanium oxide is used, no carbon dioxide gas is generated, and the green sheet is not expanded during the reaction. Therefore, a dense ceramic can be obtained without lowering the sinterability by subsequent firing.

  A change in the state of the green sheet at this time will be described with reference to FIGS. FIG. 3 and FIG. 9 are conceptual diagrams showing how the green sheet changes through the calcination and firing steps, respectively. FIG. 3 is a diagram illustrating the manufacturing method shown in FIG. The produced green sheet mainly composed of dibarium titanate and titanium oxide, and FIG. 9 show the green sheet produced by the conventional production method.

  In FIG. 3A, the green sheet 3 of the present invention does not generate carbon dioxide gas when it becomes barium titanate 4 by calcining as shown in FIG. The green sheet does not expand. Therefore, as shown in FIG. 3C, the ceramic 5 obtained through firing has good sinterability.

  On the other hand, the conventional green sheet 21 shown in FIG. 9 (a) is mainly made of barium carbonate and titanium oxide, so that when it becomes barium titanate 22 by calcination as shown in FIG. It will generate | occur | produce and the green sheet 21 in reaction will expand | swell by this. For this reason, as shown in FIG. 9C, the obtained ceramics 23 is insufficiently sintered, and in the worst case, the ceramics 23 are fragile and easily broken.

  Now, returning to the description of the method for producing the green sheet of FIG. 1, the ceramic 4 shown in FIG. 2C is obtained by firing the barium titanate 3 obtained by calcination (FIG. 1D).

  It is also possible to use what has what is called an anisotropic shape which has shapes, such as needle shape, plate shape, and column shape, as a shape of the titanium oxide mentioned above. Hereinafter, a description will be given with reference to FIG.

  FIG. 4 is a conceptual diagram of a green sheet in a manufacturing process when anisotropically shaped titanium oxide is used.

  The anisotropically shaped titanium oxide 6 and dibarium titanate 1 shown in FIG. 4A are slurried and formed into a sheet, thereby producing a green sheet 7 shown in FIG. 4B. At this time, the minor axis direction of the titanium oxide 6 can be aligned in the thickness direction of the green sheet 7 by forming the slurry by applying shear stress to the slurry at the time of producing the green sheet 7. Thereby, the reliability of the thickness direction as ceramics can be improved.

  By firing this green sheet 7 as shown in FIG. 4C, a ceramic 8 in which barium titanate is generated and the barium titanate is oriented in the arrangement direction can be obtained.

  In addition, when the barium titanate having an anisotropic shape is used, the same effect as described above can be obtained.

  Further, by using both titanium oxide and dibarium titanate having an anisotropic shape, the reliability in the thickness direction as ceramics can be further improved. Hereinafter, a description will be given with reference to FIG.

  FIG. 5 is a conceptual diagram of a green sheet in a manufacturing process when both titanium oxide and dibarium titanate have anisotropic shapes.

  A green sheet 10 shown in FIG. 5 (b) is produced by slurrying titanium oxide 6 and dibarium titanate 9 having an anisotropic shape shown in FIG. 5 (a) into a sheet. At this time, when the green sheet 10 is produced by applying a shear stress to the slurry, the minor axis direction of the dibarium titanate 9 and the titanium oxide 6 can be aligned in the thickness direction of the green sheet 10. Thereby, the reliability of the thickness direction as ceramics can further be improved.

  By firing this green sheet, as shown in FIG. 5C, a ceramic 11 having high orientation can be obtained.

  Now, at the time of green sheet production, the composition of dibarium titanate and titanium oxide in the slurry is changed so that the former is the main component slurry and the latter is the main component slurry so as to have a laminated structure in the thickness direction. It is also possible to form a sheet. In this case, the produced green sheet has a multi-layer structure including a layer mainly composed of dibarium titanate and a layer mainly composed of titanium oxide. Thus, by making the slurry having the former as the main component and the slurry having the latter as the main component, the respective slurries are less likely to agglomerate, and as a result, the orientation of the produced ceramic can be improved. Has a working effect. And if the thing of an anisotropic shape is used for dibarium titanate and a titanium oxide, each minor axis direction of a dibarium titanate and a titanium oxide can be further aligned with the thickness direction of a green sheet.

  Also in the green sheet having the laminated structure obtained in this manner, carbon dioxide gas is not generated by calcination.

  FIG. 6 is a conceptual diagram showing how the green sheet having a laminated structure changes through the calcination and firing processes.

  In FIG. 6 (a), the upper layer 12a is composed of dibarium titanate as a main component, and the lower layer 12b is formed of a laminated structure whose main component is titanium oxide, as shown in FIG. 6 (b). When the barium titanate 13 is obtained, carbon dioxide gas is not generated, and expansion due to this is not generated. Therefore, as shown in FIG. 6C, the ceramic 14 obtained through firing has good sinterability.

  FIG. 7 is a conceptual diagram of a green sheet in a manufacturing process in which both titanium oxide and dibarium titanate are anisotropic and have a laminated structure in the thickness direction.

  A green sheet 12 shown in FIG. 7 (b) is produced by laminating the anisotropically shaped titanium oxide 6 and dibarium titanate 9 shown in FIG. By firing the green sheet 12, as shown in FIG. 7C, a ceramic 14 having high orientation can be obtained.

  In this way, the same applies to a green sheet having a laminated structure in the thickness direction using a slurry mainly composed of the former and a slurry mainly composed of the latter by changing the composition of dibarium titanate and titanium oxide in the slurry. The effect can be obtained.

  In the case of producing a ceramic electronic component, for example, a multilayer ceramic capacitor, using the green sheet of the present invention described above, a laminate is produced by alternately laminating the green sheet and the electrode layer of the present invention. Can be manufactured through the steps of debuying, calcination, and firing. At this time, a conventionally used material such as nickel, silver, palladium, or the like can be used for the electrode layer.

  Thus, by using the green sheet of the present invention, the ceramic electronic component has improved sinterability, so that the dielectric constant and reliability as the ceramic electronic component can be improved. In particular, by using a green sheet using an anisotropic shape, the dielectric constant and the reliability can be further improved.

  In addition to the ceramic capacitors described above, the ceramic electronic components that can use the green sheet of the present invention include piezoelectric sensors, multilayer actuators, piezoelectric oscillators, piezoelectric electronic components typified by piezoelectric filters, multilayer inductors, noise Examples thereof include a magnetic electronic component typified by a filter, a bandpass filter, an antenna switch module, a wireless run module, a high-frequency module typified by a Bluetooth module, an electronic component for a thermistor, or a composite component thereof.

  In the present embodiment, Ba is used as the element A, but Ca and Sr can also be used.

  The present invention is characterized in that a perovskite compound powder suitable for thinning can be obtained, and is particularly useful for ceramic devices and the like that are required to be miniaturized.

The step figure which showed the manufacturing method of the barium titanate powder in the 1 embodiment of the present invention Conceptual diagram showing the same barium titanate powder and method for producing ceramics using the same The conceptual diagram which showed the change in the manufacturing process of the green sheet of this invention Conceptual diagram Conceptual diagram Conceptual diagram Conceptual diagram Step diagram showing a conventional method for producing barium titanate Conceptual diagram showing changes in the manufacturing process of conventional green sheets

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dibarium titanate 2 Titanium oxide 3 Green sheet 4 Barium titanate 5 Ceramics 6 Anisotropic titanium oxide 7 Green sheet 8 Ceramics 9 Anisotropic dibarium titanate 10 Green sheet 11 Ceramics 12 Green sheet 12a Upper layer 12b Lower layer 14 Ceramics

Claims (4)

A green sheet using at least Ba and Ti, and Ba ₂ TiO ₄ having a larger number of moles of Ba than the number of moles of Ti, and TiO ₂ containing at least Ti , wherein the Ba ₂ TiO ₄ and the TiO ₂ are A green sheet characterized by an anisotropic shape . Ba ₂ TiO _Four And a layer containing TiO as a main component and the TiO ₂ The green sheet of Claim 1 which has a layer which has as a main component. A ceramic electronic component using the green sheet according to claim 1. BaCO _Three And TiO ₂ And then calcined Ba ₂ TiO _Four A step of producing
Ba ₂ TiO _Four And TiO ₂ A step of mixing a binder with a binder to produce a slurry;
A method of producing a green sheet by applying the slurry onto a base film and then drying to produce a green sheet.

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