JP7612965B2 - Dielectric ceramic composition and multilayer ceramic capacitor including the same - Google Patents

Description

The present invention relates to a dielectric ceramic composition that can improve reliability and a multilayer ceramic capacitor that includes the same.

In general, electronic components using ceramic materials, such as capacitors, inductors, piezoelectric elements, varistors, or thermistors, comprise a ceramic body made of ceramic material, an internal electrode formed inside the body, and an external electrode disposed on the surface of the ceramic body so as to be connected to the internal electrode.

Recently, as electronic products have become smaller and more multifunctional, chip components have also become smaller and more functional, so there is a demand for multilayer ceramic capacitors that are small in size and have high capacitance.

One way to achieve both miniaturization and high capacity in multilayer ceramic capacitors is to reduce the thickness of the internal dielectric layers and electrode layers and stack a large number of them. Currently, the thickness of the dielectric layer is about 0.6 μm, and development is continuing to make it thinner.

Under these circumstances, ensuring the reliability of the dielectric layer has become an important issue for dielectric materials. At the same time, the defect rate is increasing due to deterioration of the insulation resistance of the dielectric, and problems have emerged in which it is difficult to manage quality and yield.

To solve these problems, a new method is needed that can ensure high reliability not only in terms of the structure of multilayer ceramic capacitors, but also in terms of their dielectric composition.

If a dielectric composition that can further improve the reliability level at the current level can be secured, it will be possible to produce even thinner multilayer ceramic capacitors.

The object of the present invention is to provide a dielectric ceramic composition that can improve reliability and a multilayer ceramic capacitor including the same.

One embodiment of the present invention provides a dielectric ceramic composition comprising a BaTiO3 _- based matrix main component and an auxiliary component, the auxiliary component comprising a trivalent lanthanum group rare earth element A and terbium (Tb) as rare earth elements, and a ratio (Tb/A) of the content of the terbium (Tb) to the content of the trivalent lanthanum group rare earth element A satisfies 0.15≦Tb/A<0.50.

Another embodiment of the present invention provides a multilayer ceramic capacitor including: a ceramic body including a dielectric layer; a first internal electrode and a second internal electrode disposed to face each other with the dielectric layer therebetween; a first external electrode disposed outside the ceramic body and electrically connected to the first internal electrode; and a second external electrode electrically connected to the second internal electrode, the dielectric layer including a dielectric ceramic composition, the dielectric ceramic composition including a _BaTiO3 -based matrix main component and a subcomponent, the subcomponent including a trivalent lanthanum group rare earth element A and terbium (Tb) as rare earth elements, and a ratio (Tb/A) of the content of the terbium (Tb) to the content of the trivalent lanthanum group rare earth element A satisfies 0.15≦Tb/A<0.50.

According to one embodiment of the present invention, the dielectric ceramic composition contained in the dielectric layer in the ceramic body contains terbium (Tb), a new rare earth element, as an accessory component, and by controlling the content of terbium, it is possible to improve reliability, such as by improving insulation resistance.

1 is a schematic perspective view showing a multilayer ceramic capacitor according to an embodiment of the present invention; 2 is a cross-sectional view taken along line II' in FIG. 1; 1 is a graph showing evaluation results of a reliability test (HALT) performed under severe conditions according to an embodiment of the present invention and a comparative example.

In the following, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more completely explain the present invention to those having average knowledge in the art. Therefore, the shapes and sizes of elements in the drawings may be enlarged or reduced (or highlighted or simplified) for clearer explanation, and elements indicated by the same reference numerals in the drawings are the same elements.

Figure 1 is a schematic perspective view showing a multilayer ceramic capacitor according to one embodiment of the present invention, and Figure 2 is a cross-sectional view taken along line II' in Figure 1.

Referring to FIG. 1 and FIG. 2, a multilayer ceramic capacitor 100 according to an embodiment of the present invention includes a ceramic body 110 including a dielectric layer 111, a first internal electrode 121 and a second internal electrode 122 arranged to face each other with the dielectric layer 111 therebetween, a first external electrode 131 arranged on the outside of the ceramic body 110 and electrically connected to the first internal electrode 121, and a second external electrode 132 electrically connected to the second internal electrode 122.

In the multilayer ceramic capacitor 100 according to one embodiment of the present invention, the "length direction" is defined as the "L" direction in FIG. 1, the "width direction" as the "W" direction, and the "thickness direction" as the "T" direction. Here, the "thickness direction" can be used in the same concept as the direction in which the dielectric layers are stacked, i.e., the "stacking direction".

There are no particular limitations on the shape of the ceramic body 110, but it can be a hexahedron as shown in the drawing.

The internal electrodes 121, 122 formed inside the ceramic body 110 have one end exposed to one surface of the ceramic body or the other surface opposite the one surface.

The internal electrodes 121 and 122 may be paired with a first internal electrode 121 and a second internal electrode 122 having different polarities.

One end of the first internal electrode 121 may be exposed to one side of the ceramic body, and one end of the second internal electrode 122 may be exposed to the other side opposite the first side.

First and second external electrodes 131 and 132 may be formed on one side of the ceramic body 110 and the other side opposite the one side, and may be electrically connected to the internal electrodes.

The material for forming the first and second internal electrodes 121, 122 is not particularly limited, and the first and second internal electrodes 121, 122 can be formed using a conductive paste containing one or more of silver (Ag), lead (Pb), platinum (Pt), nickel (Ni), and copper (Cu), for example.

The first and second external electrodes 131, 132 may be electrically connected to the first and second internal electrodes 121, 122 to form a capacitance, and the second external electrode 132 may be connected to a different potential than the first external electrode 131.

The conductive material contained in the first and second external electrodes 131, 132 is not particularly limited, but nickel (Ni), copper (Cu), or an alloy thereof can be used.

The thickness of the first and second external electrodes 131, 132 can be appropriately determined depending on the application, etc., and is not particularly limited, but may be, for example, 10 to 50 μm.

According to an embodiment of the present invention, the raw material for forming the dielectric layer 111 is not particularly limited as long as it can obtain a sufficient capacitance, and may be, for example, barium titanate (BaTiO ₃ ) powder.

The material forming the dielectric layer 111 may be a powder of barium titanate (BaTiO ₃ ) or the like to which various additives, organic solvents, plasticizers, binders, dispersants, etc. may be added according to the purpose of the present invention.

The dielectric layers 111 are in a sintered state, and are integrated to the extent that the boundaries between adjacent dielectric layers cannot be discerned.

First and second internal electrodes 121 and 122 may be formed on the dielectric layer 111, and the internal electrodes 121 and 122 may be formed inside the ceramic body by sintering with a dielectric layer sandwiched therebetween.

The thickness of the dielectric layer 111 can be changed as desired depending on the capacitance design of the capacitor. In one embodiment of the present invention, the thickness of the dielectric layer after firing may preferably be 0.45 μm or less per layer.

Furthermore, the thickness of the first and second internal electrodes 121, 122 after firing may preferably be 0.45 μm or less per layer.

According to an embodiment of the present invention, the dielectric layer 111 includes a _BaTiO3 -based matrix main component and an auxiliary component, and the auxiliary component includes a trivalent lanthanum group rare earth element A and terbium (Tb) as rare earth elements, and includes a dielectric ceramic composition in which the ratio (Tb/A) of the content of the terbium (Tb) to the content of the trivalent lanthanum group rare earth element A satisfies 0.15≦Tb/A<0.50.

In particular, the trivalent lanthanum group rare earth element A can be dysprosium (Dy).

According to one embodiment of the present invention, the ratio (Tb/A) of the content of the terbium (Tb) to the content of the trivalent lanthanum group rare earth element A satisfies 0.15≦Tb/A<0.50.

When the ratio (Tb/A) of the content of the terbium (Tb) to the content of the trivalent lanthanum group rare earth element A satisfies 0.15≦Tb/A<0.50, the effect of improving reliability, such as improving insulation resistance, is excellent.

In particular, the trivalent lanthanum group rare earth element A can be dysprosium (Dy), and when the ratio (Tb/Dy) of the terbium (Tb) content to the dysprosium (Dy) content satisfies 0.15≦Tb/Dy<0.50, the effect of improving reliability, such as improving insulation resistance, is excellent.

According to one embodiment of the present invention, the dielectric ceramic composition contained in the dielectric layer in the ceramic body contains a trivalent lanthanum group rare earth element A and the rare earth element terbium (Tb) as minor components, and by controlling the content ratio of the rare earth element terbium (Tb) to the trivalent lanthanum group rare earth element A, it is possible to improve reliability, such as improving insulation resistance.

When the ratio (Tb/A) of the content of the terbium (Tb) to the content of the trivalent lanthanum group rare earth element A is less than 0.15, the effect of improving reliability by adding terbium (Tb) is small, and when the ratio of the content of the terbium (Tb) to the content of the trivalent lanthanum group rare earth element A is 0, that is, when terbium (Tb) is not added as in the conventional case, there is no effect of improving reliability and the failure rate may increase.

In addition, if the ratio (Tb/A) of the terbium (Tb) content to the trivalent lanthanum group rare earth element A content is 0.50 or more, a decrease in insulation resistance due to semiconductivity may occur.

The trivalent lanthanum group rare earth element A can be dysprosium (Dy). When the ratio (Tb/Dy) of the terbium (Tb) content to the dysprosium (Dy) content is less than 0.15, the effect of improving reliability by adding terbium (Tb) is small, and when the ratio of the terbium (Tb) content to the dysprosium (Dy) content is 0, that is, when terbium (Tb) is not added as in the conventional case, there is no effect of improving reliability and the failure rate may increase.

In addition, if the ratio (Tb/Dy) of the terbium (Tb) content to the dysprosium (Dy) content is 0.50 or more, a decrease in insulation resistance due to semiconductivity may occur.

According to one embodiment of the present invention, the total content of the trivalent lanthanum group rare earth element A and terbium (Tb) can be 0.2 mol or more and 1.5 mol or less per 100 mol of titanium (Ti) in the main component of the base material.

In particular, the trivalent lanthanum group rare earth element A can be dysprosium (Dy).

Generally, rare earth elements are added in large amounts to ensure the reliability of the dielectric inside multilayer ceramic capacitors.

Among these rare earth elements, dysprosium (Dy) is known to be effective in improving reliability by replacing Ba-site and reducing the concentration of oxygen vacancy defects when added to barium titanate (BaTiO ₃ ), which is the main component of the base material.

On the other hand, when rare earth elements with a larger ionic radius than dysprosium (Dy), such as lanthanum (La) or samarium (Sm), are used, Basite can be more effectively substituted and the concentration of oxygen vacancy defects can be reduced. However, excessive semiconductivity causes a rapid drop in insulation resistance, and this has not yet reached a practical level.

Therefore, it was thought that it would be better to use a rare earth element that has an ionic radius larger than dysprosium (Dy), but whose size difference with that of dysprosium (Dy) is not large, in order to minimize the concentration of oxygen vacancy defects to improve reliability and also to suppress semiconductor formation in order to ensure insulation resistance.

In addition, since the valence of a general rare earth element is +3, when substituting Ba (+2), it has one positive charge (D ^· _Ba ). However, when it can have a multi-valence of +4 like terbium (Tb), it can have a double positive charge (D ^· _Ba ), so the effect of reducing the concentration of oxygen vacancy defects can be doubled.

In contrast, when an element with a variable valence of +2, such as ytterbium (Yb), is substituted for Ba (+2), it is not effective in reducing the concentration of oxygen vacancy defects because it is charge neutral. For this reason, it is known that adding ytterbium (Yb) actually further deteriorates reliability.

Therefore, although it has a larger ionic radius than dysprosium (Dy), the element terbium (Tb) has multiple atoms and does not undergo semiconductivity to the extent that it reduces insulation resistance. It is therefore expected that the element will be most effective in reducing the concentration of oxygen vacancy defects and thus greatly improve the reliability of the dielectric in multilayer ceramic capacitors. As a result, a dielectric ceramic composition that uses both dysprosium (Dy) and terbium (Tb) was developed.

Previously, there have been attempts to add one or more of the rare earth elements dysprosium (Dy), gadolinium (Gd), and terbium (Tb) to dielectric ceramic compositions.

However, in the above-mentioned conventional cases, without any recognition of the above-mentioned effects of terbium (Tb), it is merely described as a rare earth element or added in small amounts, and the reality is that no specific research has been conducted on the amount of terbium (Tb) added to improve reliability.

On the other hand, in one embodiment of the present invention, it was possible to find an optimal ratio of the amount of dysprosium (Dy) and terbium (Tb) added that has an excellent effect on improving reliability.

According to one embodiment of the present invention, the total content of the trivalent lanthanum group rare earth element A and terbium (Tb) is adjusted to 0.2 moles or more and 1.5 moles or less per 100 moles of titanium (Ti) in the main component of the base material, thereby making it possible to improve reliability, such as improving insulation resistance.

When the trivalent lanthanum group rare earth element A is dysprosium (Dy), the total content of the dysprosium (Dy) and terbium (Tb) is 0.2 mol or more and 1.5 mol or less per 100 mol of titanium (Ti) in the main component of the base material.

By adjusting the total content of the above dysprosium (Dy) and terbium (Tb) to be 0.2 moles or more and 1.5 moles or less per 100 moles of titanium (Ti), which is the main component of the base material, it is possible to improve reliability, such as improving insulation resistance.

The higher the total content of rare earth elements, the more advantageous it is in terms of reliability, but as Tc moves to room temperature, the temperature characteristics drop significantly, so it is preferable to adjust the total content of dysprosium (Dy) and terbium (Tb) to 1.5 moles or less per 100 moles of titanium (Ti), which is the main component of the base material.

If the total content of dysprosium (Dy) and terbium (Tb) exceeds 1.5 moles per 100 moles of titanium (Ti), the main component of the base material, there is a possibility that temperature characteristics such as the temperature coefficient of capacitance (TCC) may decrease.

On the other hand, if the total content of dysprosium (Dy) and terbium (Tb) is less than 0.2 moles per 100 moles of titanium (Ti), which is the main component of the base material, reliability may decrease.

As described above, the multilayer ceramic capacitor 100 according to one embodiment of the present invention is an ultra-compact, high-capacity product, characterized in that the thickness of the dielectric layer 111 is 0.45 μm or less and the thickness of the first and second internal electrodes 121, 122 is 0.45 μm or less, but is not necessarily limited thereto.

In other words, since the multilayer ceramic capacitor 100 according to one embodiment of the present invention is an ultra-compact, high-capacity product, the dielectric layer 111 and the first and second internal electrodes 121, 122 are thinner than those of conventional products. In the case of products that use such thin dielectric layers and internal electrodes, research into improving reliability, such as insulation resistance, is a very important issue.

In other words, in the case of conventional multilayer ceramic capacitors, the dielectric layers and internal electrodes are relatively thicker than those included in the multilayer ceramic capacitor according to one embodiment of the present invention, so even if the composition of the dielectric ceramic composition is the same as in the conventional case, reliability has not been a major issue.

However, in products in which thin-film dielectric layers and internal electrodes are used, such as in one embodiment of the present invention, the reliability of the multilayer ceramic capacitor is important. Therefore, it is necessary to adjust the composition of the dielectric ceramic composition.

That is, in one embodiment of the present invention, the total content of the trivalent lanthanum group rare earth element A and terbium (Tb) is adjusted to 0.2 moles or more and 1.5 moles or less per 100 moles of titanium (Ti) in the main component of the base material, and in particular, the ratio (Tb/A) of the content of the terbium (Tb) to the content of the trivalent lanthanum group rare earth element A is adjusted to satisfy 0.15≦Tb/A<0.50, thereby improving reliability such as improving insulation resistance even when the dielectric layer 111 and the first and second internal electrodes 121, 122 are thin films having a thickness of 0.45 μm or less.

However, the above-mentioned thin film does not mean that the thickness of the dielectric layer 111 and the first and second internal electrodes 121, 122 is 0.45 μm or less, but should be understood as a concept including dielectric layers and internal electrodes that are thinner than those of conventional products.

Below, we will explain each component of the dielectric ceramic composition according to one embodiment of the present invention in more detail.

a) Base Material Main Component The dielectric ceramic composition according to one embodiment of the present invention may include a base material main component represented by _BaTiO3 .

According to an embodiment of the present invention, the main component of the matrix includes at least one selected from the group consisting of BaTiO ₃ , (Ba _1-x Ca _x )(Ti _1-y Ca _y )O ₃ (wherein x is 0≦x≦0.3 and y is 0≦y≦0.1), (Ba _1-x Ca _x )(Ti _{1-y Zry} )O ₃ (wherein x is 0≦x≦0.3 and y is 0≦y≦0.5), and Ba(Ti _{1-y Zry} )O ₃ (wherein 0<y≦0.5), but is not necessarily limited thereto.

The dielectric ceramic composition according to one embodiment of the present invention may have a room temperature dielectric constant of 2000 or more.

The main component of the base material is not particularly limited, but the average particle size of the main component powder may be 40 nm or more and 150 nm or less.

b) First Subcomponent According to one embodiment of the present invention, the dielectric ceramic composition necessarily contains dysprosium (Dy) and terbium (Tb) as first subcomponent elements, and may further contain 0.0 to 4.0 mol of a first subcomponent which is an oxide or carbonate containing at least one of Y, Ho, Er, Ce, Nd, Pm, Eu, Gd, Tm, Yb, Lu, and Sm, relative to 100 mol of the main component of the matrix.

In one embodiment of the present invention, the first subcomponent serves to prevent a decrease in the reliability of a multilayer ceramic capacitor to which the dielectric ceramic composition is applied.

If the content of the first subcomponent exceeds 4.0 moles, problems may occur such as a decrease in reliability or a decrease in the dielectric constant of the dielectric ceramic composition, resulting in poor high-temperature voltage resistance characteristics.

According to one embodiment of the present invention, the ratio (Tb/Dy) of the terbium (Tb) content to the dysprosium (Dy) content satisfies 0.15≦Tb/Dy<0.50.

By adjusting the ratio (Tb/Dy) of the terbium (Tb) content to the dysprosium (Dy) content so that it satisfies 0.15≦Tb/Dy<0.50, it is possible to improve reliability, such as improving insulation resistance.

When the ratio (Tb/Dy) of the terbium (Tb) content to the dysprosium (Dy) content is less than 0.15, the effect of adding terbium (Tb) in improving reliability is slight, and when the ratio of the terbium (Tb) content to the dysprosium (Dy) content is 0, that is, when terbium (Tb) is not added as in the conventional case, there is no effect of improving reliability and the failure rate may increase.

On the other hand, if the ratio (Tb/Dy) of the terbium (Tb) content to the dysprosium (Dy) content is 0.50 or more, a decrease in insulation resistance due to semiconductivity may occur.

The total content of the dysprosium (Dy) and terbium (Tb) is 0.2 moles or more and 1.5 moles or less per 100 moles of titanium (Ti), which is the main component of the base material.

By adjusting the total content of the above dysprosium (Dy) and terbium (Tb) to be 0.2 moles or more and 1.5 moles or less per 100 moles of titanium (Ti), which is the main component of the base material, it is possible to improve reliability, such as improving insulation resistance.

c) Second Subcomponent According to an embodiment of the present invention, the dielectric ceramic composition may include at least one of Mn, V, Cr, Fe, Ni, Co, Cu, and Zn as a second subcomponent. It can include an oxide or carbonate.

As the second subcomponent, an oxide or carbonate containing at least one of Mn, V, Cr, Fe, Ni, Co, Cu, and Zn may be included in an amount of 0.1 to 2.0 moles per 100 moles of the base powder.

The second subcomponent serves to lower the firing temperature of the multilayer ceramic capacitor to which the dielectric ceramic composition is applied, thereby improving the high-temperature voltage resistance characteristics.

The content of the second subcomponent and the contents of the third to sixth subcomponents described below refer to the amount contained per 100 moles of the base powder, and can be specifically defined as the moles of metal ions contained in each subcomponent.

If the content of the second subcomponent is less than 0.1 moles, the firing temperature may become high and the high-temperature voltage resistance characteristics may be slightly reduced.

In addition, if the content of the second subcomponent is 2.0 moles or more, the high-temperature withstand voltage characteristics and room-temperature resistivity may decrease.

In particular, the dielectric ceramic composition according to one embodiment of the present invention can contain a second subcomponent with a content of 0.1 to 2.0 moles per 100 moles of the main component of the base material. This allows low-temperature firing and high high-temperature voltage resistance characteristics to be obtained.

d) Third Subcomponent According to an embodiment of the present invention, the dielectric ceramic composition may include a third subcomponent which is an oxide or carbonate containing Mg, which is a fixed-valence acceptor element.

The fixed-valence acceptor element Mg can contain 0.0 to 0.5 moles of the third subcomponent per 100 moles of titanium (Ti) in the main component of the matrix.

The third minor component is a fixed-valence acceptor or a compound containing the same, and can act as an acceptor to reduce the concentration of electrons. By adding 0.0 to 0.5 moles of Mg, the fixed-valence acceptor element of the third minor component, to 100 moles of titanium (Ti) of the main component of the base material, the reliability improvement effect due to the n-type can be maximized.

If the content of the third subcomponent exceeds 0.5 moles per 100 moles of the base powder, this is not preferable because it causes a problem of a low dielectric constant.

However, according to one embodiment of the present invention, it is preferable to add 0.5 moles of the third subcomponent to 100 moles of titanium (Ti) in order to maximize the effect of improving reliability by making it n-type, but this is not necessarily limited to this amount, and it is also possible to add 0.5 moles or less or a small amount more than 0.5 moles.

e) Fourth Subcomponent According to one embodiment of the present invention, the dielectric ceramic composition may include a fourth subcomponent which is an oxide or carbonate containing Ba.

The dielectric ceramic composition may contain 0.0 to 4.15 moles of a fourth subcomponent, which is an oxide or carbonate containing Ba, per 100 moles of the main base material component.

The content of the fourth minor component can be determined based on the content of the Ba element contained in the fourth minor component, regardless of the form of addition, such as oxide or carbonate.

The fourth subcomponent can play a role in promoting sintering within the dielectric ceramic composition and adjusting the dielectric constant, and if its content exceeds 4.15 moles per 100 moles of the main component of the base material, problems such as a low dielectric constant and a high firing temperature may occur.

f) Fifth Subcomponent According to one embodiment of the present invention, the dielectric ceramic composition may include a fifth subcomponent including at least one selected from the group consisting of oxides and carbonates of at least one element of Ca and Zr.

The dielectric ceramic composition may contain 0.0 to 20.0 moles of a fifth subcomponent, which is an oxide or carbonate containing at least one of Ca and Zr, per 100 moles of the main base material component.

The content of the fifth minor component can be based on the content of at least one of the elements Ca and Zr contained in the fifth minor component, regardless of the added form such as oxide or carbonate.

The fifth subcomponent forms a core-shell structure in the dielectric ceramic composition to improve the dielectric constant and reliability. When the fifth subcomponent is contained in an amount of 20.0 moles or less per 100 moles of the main base material component, a high dielectric constant is achieved, and a dielectric ceramic composition with good high-temperature voltage resistance characteristics can be provided.

If the content of the fifth subcomponent exceeds 20.0 moles per 100 moles of the main component of the base material, the room temperature dielectric constant decreases and the high temperature withstand voltage characteristics also decrease.

g) Sixth Subcomponent According to an embodiment of the present invention, the dielectric ceramic composition may include, as a sixth subcomponent, an oxide containing at least one of Si and Al or a glass compound containing Si.

The dielectric ceramic composition may further contain 0.0 to 4.0 moles of a sixth subcomponent, which is an oxide containing at least one of Si and Al or a glass compound containing Si, per 100 moles of the main base material component.

The content of the sixth minor component can be based on the content of at least one of the elements Si and Al contained in the sixth minor component, regardless of the added form such as glass, oxide, or carbonate.

The sixth subcomponent plays a role in lowering the firing temperature of the multilayer ceramic capacitor to which the dielectric ceramic composition is applied, and improving the high-temperature voltage resistance characteristics.

If the content of the sixth subcomponent exceeds 4.0 moles per 100 moles of the main component of the base material, this is not preferable because it reduces sinterability and density and can cause problems such as secondary phase formation.

In particular, according to one embodiment of the present invention, the dielectric ceramic composition contains Al at a content of 4.0 mol or less, which allows for uniform control of grain growth, and is effective in improving voltage resistance characteristics and reliability, as well as DC-bias characteristics.

The present invention will be described in more detail below with reference to examples and comparative examples. However, these are intended to aid in a concrete understanding of the invention, and the scope of the present invention is not limited to these examples.

(Example)
In the embodiment of the present invention, additives such as Dy, Tb, Al, Mg, Mn, etc., binders, and organic solvents such as ethanol are added to a dielectric raw material powder including barium titanate ( _BaTiO3 ) powder, and the mixture is wet mixed to prepare a dielectric slurry, and then the dielectric slurry is applied onto a carrier film and dried to provide a ceramic green sheet, thereby forming a dielectric layer.

In this case, all the additive elements were added in a monodispersed manner so that their size was 40% or less relative to the barium titanate.

In particular, the content of dysprosium (Dy) and terbium (Tb) among the added rare earth elements was set to 1.5 moles per 100 moles of titanium (Ti), which is the main component of the base material.

Of the above examples, Example 1 was produced by adding 1.5 moles of dysprosium (Dy) and terbium (Tb) to 100 moles of titanium (Ti), which is the main component of the base material, and Example 2 was produced by adjusting the ratio (Tb/Dy) of the terbium (Tb) content to the dysprosium (Dy) content to be 0.15 or more and less than 0.5.

The ceramic green sheet can be made by mixing ceramic powder, binder, and solvent to produce a slurry, and then forming the slurry into a sheet with a thickness of several μm using a doctor blade method.

Next, a conductive paste for the internal electrodes can be prepared that contains 40 to 50 parts by weight of nickel powder with an average particle size of 0.1 to 0.2 μm.

The conductive paste for the internal electrodes was applied onto the green sheets by screen printing to form the internal electrodes, and the green sheets on which the internal electrode patterns were arranged were stacked to form a laminate, which was then crimped and cut.

The cut laminate was then heated to remove the binder, and then fired at high temperature in a reducing atmosphere to form the ceramic body.

In the firing process, the material was fired in a reducing atmosphere (0.1% _H2 /99.9% _N2 , _H2O / _H2 / _N2 atmosphere) at a temperature of 1100 to 1200°C for 2 hours, and then oxidized and heat-treated in a nitrogen ( _N2 ) atmosphere at 1000°C for 3 hours.

Next, the fired ceramic body was subjected to a termination process using copper (Cu) paste and electrode firing to complete the external electrodes.

In addition, the dielectric layer 111 and the first and second internal electrodes 121, 122 inside the ceramic body 110 were manufactured so that their thickness after firing would be 0.45 μm or less.

(Comparative Example 1)
In Comparative Example 1, dysprosium (Dy) and terbium (Tb) were added so that the total content was 1.8 moles per 100 moles of titanium (Ti), which is the main component of the base material, and the other manufacturing processes were the same as those of the above-mentioned examples.

(Comparative Example 2)
In Comparative Example 2, dysprosium (Dy) and terbium (Tb) were added so that the total content was 2.1 moles per 100 moles of titanium (Ti), which is the main component of the base material, and the other manufacturing processes were the same as those of the above-mentioned examples.

(Comparative Example 3)
Comparative Example 3 is a conventional dielectric ceramic composition, which does not contain terbium (Tb) and contains only dysprosium (Dy). The other manufacturing processes are the same as those of the above-mentioned examples.

(Comparative Example 4)
In Comparative Example 4, the terbium (Tb) content was added so that the ratio (Tb/Dy) of the dysprosium (Dy) content to the terbium (Tb) content was less than 0.15, and the other manufacturing processes were the same as those of the above-mentioned examples.

(Comparative Example 5)
In the case of Comparative Example 5, the terbium (Tb) content was added so that the ratio (Tb/Dy) of the dysprosium (Dy) content to the terbium (Tb) content was 0.5 or more, and the other manufacturing processes were the same as those of the above-mentioned examples.

The prototype multilayer ceramic capacitor (prototype MLCC) samples completed as described above, Examples 1 and 2 and Comparative Examples 1 to 5, were subjected to temperature characteristic tests and HALT tests to evaluate the failure rate.

The above temperature characteristic test measures the temperature coefficient of capacitance (TCC), and the X5R temperature characteristic must meet a capacitance of ±15% in the range of -55°C to 85°C based on a 25°C capacitance standard, and the X6S temperature characteristic must meet a capacitance of ±22% in the range of -55°C to 105°C based on a 25°C capacitance standard.

In the above HALT test, 40 multilayer ceramic capacitor (MLCC) chips were mounted on a substrate for each sample, and measurements were performed for 12 hours at 125°C and 20V (DC) applied.

The following Table 1 shows the above-mentioned electrical characteristics of the prototype multilayer ceramic capacitor (prototype MLCC) chips according to the experimental examples (Examples 1 and 2 and Comparative Examples 1 and 2).

Referring to Table 1 above, it can be seen that in Comparative Example 1 and Comparative Example 2, where the total content of dysprosium (Dy) and terbium (Tb) exceeds 1.5 moles per 100 moles of titanium (Ti), the main component of the base material, not only the X6S temperature characteristics but also the X5R temperature characteristics are not satisfied.

In contrast, in Example 1 of the present invention, the total content of dysprosium (Dy) and terbium (Tb) is 1.5 moles or less per 100 moles of titanium (Ti) in the main component of the base material, and it can be confirmed that not only the X6S temperature characteristics but also the X5R temperature characteristics are satisfied, and that there is also an excellent improvement in reliability.

Figure 3 is a graph showing the evaluation results of the HALT test for the examples of the present invention and the comparative examples.

Referring to Figure 3, in the case of Comparative Example 3 of the present invention (a), the composition is the same as that of the conventional dielectric ceramic composition, but terbium (Tb) is not added, and only dysprosium (Dy) is added. Here, it can be seen that the number of defective pieces after the HALT test was 5, which is a high defect rate.

In the case of Comparative Example 4 (b) of the present invention, the terbium (Tb) content was added so that the ratio (Tb/Dy) of the dysprosium (Dy) content to the terbium (Tb) content was less than 0.15, and it can be seen that the number of defective pieces after the HALT test was 9, which is a high defect rate.

This is thought to be because the amount of terbium (Tb) added is small relative to the amount of dysprosium (Dy) added, and the effect of adding terbium (Tb) in improving reliability is minimal.

In contrast, in the case of Example 2 of the present invention (c), where the ratio (Tb/Dy) of the terbium (Tb) content to the dysprosium (Dy) content is 0.15 or more and less than 0.5, it can be confirmed that the number of defective pieces after the HALT test is 0, which is an excellent improvement in reliability.

On the other hand, in the case of Comparative Example 5 (d) of the present invention, the ratio (Tb/Dy) of the terbium (Tb) content to the dysprosium (Dy) content was 0.5 or more, and almost all samples were found to have poor reliability.

When the ratio (Tb/Dy) of the terbium (Tb) content to the dysprosium (Dy) content is 0.50 or more, it is believed that a decrease in insulation resistance occurs due to semiconductor formation.

Although the embodiments of the present invention have been described in detail above, it will be apparent to those with ordinary skill in the art that the scope of the present invention is not limited thereto, and that various modifications and variations are possible without departing from the technical concept of the present invention as described in the claims.

[Item 1]
Contains _BaTiO3 -based base material main component and subcomponents,
The auxiliary component contains a trivalent lanthanum group rare earth element A and terbium (Tb) as rare earth elements,
A dielectric ceramic composition, wherein a ratio (Tb/A) of the content of said terbium (Tb) to the content of said trivalent lanthanum group rare earth element A satisfies 0.15≦Tb/A<0.50.
[Item 2]
2. The dielectric ceramic composition according to item 1, wherein the trivalent lanthanum group rare earth element A is dysprosium (Dy).
[Item 3]
3. The dielectric ceramic composition according to item 1 or 2, wherein the total content of the trivalent lanthanum group rare earth element A and terbium (Tb) is 0.2 mol or more and 1.5 mol or less per 100 mol of titanium (Ti) in the main component of the matrix.
[Item 4]
The dielectric ceramic composition according to any one of items 1 to 3, further comprising 0.0 to 4.0 mol of a first subcomponent which is an oxide or carbonate containing at least one of Y, Ho, Er, Ce, Nd, Pm, Eu, Gd, Tm, Yb, Lu, and Sm relative to 100 mol of the base material main component.
[Item 5]
The dielectric ceramic composition according to any one of items 1 to 4, further comprising 0.1 to 2.0 mol of a second auxiliary component which is an oxide or carbonate containing at least one of Mn, V, Cr, Fe, Ni, Co, Cu, and Zn, relative to 100 mol of the base material main component.
[Item 6]
The dielectric ceramic composition according to any one of items 1 to 5, further comprising 0.0 to 0.5 moles of a third subcomponent which is an oxide or carbonate containing Mg as a fixed valence acceptor element per 100 moles of titanium (Ti) in the base material main component.
[Item 7]
7. The dielectric ceramic composition according to any one of claims 1 to 6, further comprising 0.0 to 4.15 mol of a fourth subcomponent which is an oxide or carbonate containing Ba relative to 100 mol of the base material main component.
[Item 8]
8. The dielectric ceramic composition according to any one of items 1 to 7, wherein the dielectric ceramic composition contains 0.0 to 20.0 mol of a fifth subcomponent which is an oxide or carbonate containing at least one of Ca and Zr relative to 100 mol of the base material main component.
[Item 9]
The dielectric ceramic composition further contains 0.0 to 4.0 mol of a sixth subcomponent which is an oxide containing at least one of Si and Al or a glass compound containing Si, relative to 100 mol of the base material main component. The dielectric ceramic composition according to any one of claims 1 to 8.
[Item 10]
a ceramic body including a dielectric layer, and a first internal electrode and a second internal electrode disposed opposite each other with the dielectric layer interposed therebetween;
a first external electrode disposed outside the ceramic body and electrically connected to the first internal electrode, and a second external electrode electrically connected to the second internal electrode,
the dielectric layer comprises a dielectric ceramic composition;
The dielectric ceramic composition contains a _BaTiO3- based matrix main component and a subcomponent,
The auxiliary component contains a trivalent lanthanum group rare earth element A and terbium (Tb) as rare earth elements,
A multilayer ceramic capacitor, wherein a ratio (Tb/A) of the content of the terbium (Tb) to the content of the trivalent lanthanum group rare earth element A satisfies 0.15≦Tb/A<0.50.
[Item 11]
Item 11. The multilayer ceramic capacitor according to item 10, wherein the trivalent lanthanum group rare earth element A is dysprosium (Dy).
[Item 12]
Item 12. The multilayer ceramic capacitor according to item 10 or 11, wherein the total content of the trivalent lanthanum group rare earth element A and terbium (Tb) is 0.2 mol or more and 1.5 mol or less per 100 mol of titanium (Ti) in the main component of the base material.
[Item 13]
13. The multilayer ceramic capacitor according to any one of items 10 to 12, wherein the dielectric ceramic composition further contains 0.0 to 4.0 mol of a first subcomponent which is an oxide or carbonate containing at least one of Y, Ho, Er, Ce, Nd, Pm, Eu, Gd, Tm, Yb, Lu, and Sm relative to 100 mol of the base material main component.
[Item 14]
Item 14. The multilayer ceramic capacitor according to any one of items 10 to 13, wherein the dielectric ceramic composition further contains 0.1 to 2.0 mol of a second subcomponent which is an oxide or carbonate containing at least one of Mn, V, Cr, Fe, Ni, Co, Cu, and Zn, relative to 100 mol of the base material main component.
[Item 15]
Item 15. The multilayer ceramic capacitor according to any one of items 10 to 14, wherein the dielectric ceramic composition further contains 0.0 to 0.5 mol of a third subcomponent which is an oxide or carbonate containing Mg as a fixed valence acceptor element per 100 mol of titanium (Ti) in the base material main component.
[Item 16]
Item 16. The multilayer ceramic capacitor according to any one of items 10 to 15, wherein the dielectric ceramic composition further contains 0.0 to 4.15 mol of a fourth subcomponent which is an oxide or carbonate containing Ba, and 0.0 to 20.0 mol of a fifth subcomponent which is an oxide or carbonate containing at least one of Ca and Zr, relative to 100 mol of the base material main component.
[Item 17]
Item 17. The multilayer ceramic capacitor according to any one of items 10 to 16, wherein the dielectric ceramic composition further contains 0.0 to 4.0 mol of a sixth subcomponent which is an oxide containing at least one of Si and Al or a glass compound containing Si, relative to 100 mol of the base material main component.
[Item 18]
Item 18. The multilayer ceramic capacitor according to any one of items 10 to 17, wherein the dielectric layers have a thickness of 0.45 μm or less, and the first and second internal electrodes have a thickness of 0.45 μm or less.

110 Ceramic body 111 Dielectric layer 121 First internal electrode 122 Second internal electrode 131 First external electrode 132 Second external electrode

Claims (13)

Contains _BaTiO3 -based base material main component and subcomponents,
The auxiliary component contains a trivalent lanthanum group rare earth element A and terbium (Tb) as rare earth elements,
a ratio (Tb/A) of the content of the terbium (Tb) to the content of the trivalent lanthanum group rare earth element A satisfies 0.15≦Tb/A<0.50;
the trivalent lanthanum group rare earth element A is dysprosium (Dy);
The total content of the trivalent lanthanum group rare earth element A and terbium (Tb) is 0.2 mol or more and 1.5 mol or less per 100 mol of titanium (Ti) in the main component of the base material,
The auxiliary component does not contain Mg.
Dielectric ceramic composition. The dielectric ceramic composition according to claim 1, further comprising 0.0 to 4.0 moles of a first subcomponent which is an oxide or carbonate containing at least one of Y, Ho, Er, Ce, Nd, Pm, Eu, Gd, Tm, Yb, Lu, and Sm per 100 moles of the main component of the base material. The dielectric ceramic composition according to claim 1 or 2 further contains 0.1 to 2.0 moles of a second subcomponent which is an oxide or carbonate containing at least one of Mn, V, Cr, Fe, Ni, Co, Cu, and Zn per 100 moles of the main component of the base material. The dielectric ceramic composition according to any one of claims 1 to 3, further comprising 0.0 to 4.15 moles of a fourth subcomponent which is an oxide or carbonate containing Ba per 100 moles of the main matrix component. The dielectric ceramic composition according to any one of claims 1 to 4, wherein the dielectric ceramic composition contains 0.0 to 20.0 moles of a fifth subcomponent which is an oxide or carbonate containing at least one of Ca and Zr per 100 moles of the main component of the base material. The dielectric ceramic composition according to any one of claims 1 to 5, further comprising 0.0 to 4.0 moles of a sixth subcomponent which is an oxide containing at least one of Si and Al or a glass compound containing Si, per 100 moles of the main base material component. a ceramic body including a dielectric layer, and a first internal electrode and a second internal electrode disposed opposite each other with the dielectric layer interposed therebetween;
a first external electrode disposed outside the ceramic body and electrically connected to the first internal electrode, and a second external electrode electrically connected to the second internal electrode,
the dielectric layer comprises a dielectric ceramic composition;
The dielectric ceramic composition contains a _BaTiO3- based matrix main component and a subcomponent,
The auxiliary component contains a trivalent lanthanum group rare earth element A and terbium (Tb) as rare earth elements,
a ratio (Tb/A) of the content of the terbium (Tb) to the content of the trivalent lanthanum group rare earth element A satisfies 0.15≦Tb/A<0.50;
the trivalent lanthanum group rare earth element A is dysprosium (Dy);
The total content of the trivalent lanthanum group rare earth element A and terbium (Tb) is 0.2 mol or more and 1.5 mol or less per 100 mol of titanium (Ti) in the main component of the base material,
The auxiliary component does not contain Mg.
Multilayer ceramic capacitor. The multilayer ceramic capacitor according to claim 7, wherein the dielectric ceramic composition further contains 0.0 to 4.0 moles of a first subcomponent which is an oxide or carbonate containing at least one of Y, Ho, Er, Ce, Nd, Pm, Eu, Gd, Tm, Yb, Lu, and Sm per 100 moles of the main component of the base material. The multilayer ceramic capacitor according to claim 7 or 8, wherein the dielectric ceramic composition further contains 0.1 to 2.0 moles of a second subcomponent which is an oxide or carbonate containing at least one of Mn, V, Cr, Fe, Ni, Co, Cu, and Zn, per 100 moles of the main component of the base material. The multilayer ceramic capacitor according to any one of claims 7 to 9, wherein the dielectric ceramic composition further contains 0.0 to 4.15 moles of a fourth subcomponent which is an oxide or carbonate containing Ba per 100 moles of the main base material component. The multilayer ceramic capacitor according to any one of claims 7 to 10, wherein the dielectric ceramic composition further contains 0.0 to 20.0 moles of a fifth subcomponent which is an oxide or carbonate containing at least one of Ca and Zr. The multilayer ceramic capacitor according to any one of claims 7 to 11, wherein the dielectric ceramic composition further contains 0.0 to 4.0 moles of a sixth subcomponent which is an oxide containing at least one of Si and Al or a glass compound containing Si, per 100 moles of the main component of the base material. The multilayer ceramic capacitor according to any one of claims 7 to 12, wherein the thickness of the dielectric layer is 0.45 μm or less, and the thickness of the first internal electrode and the second internal electrode is 0.45 μm or less.