JP3050225B1 - Dielectric ceramic composition, multilayer ceramic capacitor using the same, and method of manufacturing the same - Google Patents

Abstract

An object of the present invention is to provide a dielectric ceramic composition having improved relative dielectric constant and insulation resistance. SOLUTION: The present invention is a dielectric porcelain composition represented by the following (Formula 1). Embedded image

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic composition used for a ceramic capacitor used for various electronic equipment such as an electronic tuner of a passive machine of a television, a portable telephone, a video camera and the like, and a multilayer ceramic capacitor using the same. And a method of manufacturing the same.

[0002]

2. Description of the Related Art A multilayer ceramic capacitor is made of BaTi.
After alternately laminating a dielectric layer mainly composed of O ₃ and an internal electrode layer to form a laminate and firing it, an external electrode is formed on the end face of the laminate to form a plurality of parallel equivalent ceramic capacitors. Has been realized.

Attempts have been made to reduce the cost by using inexpensive base metal Ni as the material of the internal electrode layer.
When i is used as the internal electrode layer, the dielectric layer mainly composed of BaTiO ₃ and Ni must be fired simultaneously in a reducing atmosphere in which Ni is not oxidized. Therefore, a non-reducible ceramic material has been developed as a material that is not reduced even when fired in a neutral or reducing atmosphere.
₃ It is known that the addition of _{MnO 2, Yb 2 O 3,} Dy 2 D 3, ThO 2 ( e.g. see Japanese Patent Kokoku 6-50700).

[0004] Such a dielectric ceramic composition has a relative dielectric constant of 12000 to 13000 and an insulation resistance of about 10 ⁹ Ω.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a dielectric ceramic composition further improved in relative dielectric constant and insulation resistance, a multilayer ceramic capacitor using the same, and a method of manufacturing the same. It is.

[0006]

Means for Solving the Problems To achieve this object, a dielectric ceramic composition of the present invention is represented by the following formula (2).

[0007]

Embedded image

Although the Mn component contributes to the improvement of the insulation resistance,
At the same time, the dielectric constant is reduced. Therefore, when Mn ₃ O ₄ is added instead of MnO ₂ , the amount of the Mn component to be added becomes smaller than that when MnO is added, so that a decrease in relative dielectric constant can be minimized. Also,
Replacing part of Ba with Ca increases the relative dielectric constant. Furthermore, only three components of BaO, Al ₂ O ₃ and SiO ₂
A glass having a predetermined composition consisting of a predetermined amount of 0.01 to 0.5
By adding the weight%, sinterability is improved and high dielectric
Rate. In addition, this glass
Even if the laminates are stacked and fired, the laminates adhere to each other.
Few.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The invention described in claim 1 of the present invention is a dielectric ceramic composition represented by the following formula (2), which can provide a dielectric ceramic composition having a high relative dielectric constant and high insulation resistance.

According to a second aspect of the present invention, there is provided a laminated body in which dielectric layers and internal electrode layers are alternately laminated, and an external electrode provided on an exposed end face of the internal electrode layer of the laminated body.
The dielectric layer is a multilayer ceramic capacitor formed by using the dielectric ceramic composition represented by Chemical Formula 2, and has a large capacity and high reliability.

According to a third aspect of the present invention, there is provided the multilayer ceramic capacitor according to the second aspect, wherein the internal electrode layer is made of a metal containing Ni as a main component. It can be planned.

According to a fourth aspect of the present invention, there is provided a method of forming a laminate by alternately laminating a green sheet formed using a dielectric material and an internal electrode paste containing Ni as a main component, Heating the laminate at a temperature lower than the temperature at which the green sheets start to sinter; and firing the laminate in a reducing atmosphere at a temperature lower than the melting point of Ni. Forming a multilayer ceramic capacitor having a step of forming an external electrode, wherein the dielectric material has a composition represented by the following chemical formula (2). A highly reliable multilayer ceramic capacitor can be obtained.

An embodiment of the present invention will be described below by taking a multilayer ceramic capacitor as an example.

FIG. 1 is a partial cross-sectional perspective view of a multilayer ceramic capacitor according to the present embodiment.
Reference numeral 2 denotes an internal electrode layer, and reference numeral 3 denotes an external electrode. A multilayer ceramic capacitor is formed by providing external electrodes 3 at both ends of a multi-layer structure in which dielectric layers 1 and internal electrode layers 2 are alternately stacked.

Next, a method for manufacturing the multilayer ceramic capacitor of the present invention will be described.

First, high-purity BaCO ₃ , CaCO ₃ , TiO ₂ , ZrO ₂ , Y ₂ O ₃ , M
As shown in Table 1, carbonates are converted to oxides in ternary glasses of n ₃ O ₄ , Dy ₂ O ₃ , and BaO—Al ₂ O ₃ —SiO ₂ , and composition ratios outside and within the range of the present invention. Was weighed so that

[0017]

[Table 1]

Next, the mixture was put into a ball mill equipped with zirconia balls together with pure water, wet-mixed, and dehydrated and dried. Next, the dried powder was put into a high-purity alumina crucible and calcined in air at 1100 ° C. for 2 hours.

Thereafter, the calcined powder was put into a ball mill equipped with zirconia balls together with pure water, wet-pulverized, and dehydrated and dried. At this time, the average particle size of the pulverized powder was adjusted to 2 μm or less. Next, a polyvinyl butyral resin as an organic binder, BBP (benzyl butyl phthalate) as a plasticizer, and n-butyl acetate as a solvent were added to the pulverized powder, and mixed with a ball mill equipped with zirconia to prepare a slurry. Next, after vacuum defoaming this slurry,
A green sheet was formed by forming a film into a film by a doctor blade method. At this time, the thickness of the dried green sheet was set to about 20 μm.

Next, screen printing was performed on this green sheet using an electrode paste made of Ni powder having an average particle size of about 1.0 μm so as to form a desired pattern. N
The i powder used had a particle diameter smaller than the thickness of the dielectric layer 1 sandwiched between the internal electrode layers 2.

Next, 100 green sheets on which the internal electrode patterns have been formed are overlapped with each other so that the internal electrode patterns face each other with the green sheets interposed therebetween, and heated and pressed to be integrated, and then 3.8 mm in width and 1.8 mm in length. An unsintered laminate was prepared by cutting into dimensions.

Next, this unsintered laminate is placed in a zirconia sheath covered with zirconia powder, heated to 350 ° C. in the air to burn the organic binder, and then placed in N ₂ + H ₂ .
The sintered body was obtained by firing at 1300 ° C. for 2 hours.

Next, a commercially available copper paste for baking in a nitrogen atmosphere at 900 ° C. was applied as an external electrode 3 to the end face of the obtained sintered body and baked by a continuous belt of a mesh type to obtain a multilayer ceramic capacitor. The thickness of the dielectric layer 1 was about 12 μm, and the thickness of the internal electrode layer 2 was about 2 to 2.5 μm.

Next, the capacitance and dielectric loss of the obtained multilayer ceramic capacitor were measured at a frequency of 1 in a thermostat at 20 ° C.
The relative dielectric constant was calculated from the capacitance by using (Equation 1) based on the measurement at kHz and an input signal level of 1.0 Vrms.

[0025]

(Equation 1)

Thereafter, 16 V DC was applied for 1 minute, and the insulation resistance at that time was measured. The above measurement results are shown in (Table 2).

[0027]

[Table 2]

As is clear from Table 2, the multilayer ceramic capacitor manufactured using the dielectric ceramic composition within the scope of the present invention has a high relative permittivity, and has practically sufficient dielectric loss and insulation resistance. The value was shown. On the other hand, a multilayer ceramic capacitor produced using a dielectric ceramic composition outside the scope of the present invention tended to have a low relative dielectric constant and insulation resistance.

That is, by replacing BaO with CaO, it is effective to increase the relative dielectric constant and insulation resistance and reduce the dielectric loss. In particular, for the relative permittivity, x = 0.0
Tends to be high in the range of 01 to 0.05 mol,
This range is effective for improving the relative dielectric constant. Also,
At this time, the particle size of the sintered body is 2 to 3 μm, which is smaller than the case where the relative dielectric constant is increased by other inorganic additives, and improves the reliability and strength of the large-capacity multilayer ceramic capacitor. Is effective in Increasing the strength has the effect of suppressing the occurrence of cracks due to thermal and mechanical stress generated when mounting the multilayer ceramic capacitor. When x is smaller than 0.001 mol, not only the relative permittivity but also the insulation resistance decreases, which is not suitable for practical use. On the other hand, when it exceeds 0.05 mol, the relative dielectric constant decreases.

ZrO ₂ contributes as a shifter by substituting with TiO ₂ during firing.
When the substitution exceeds y = 0.2 mol, the Curie point shifts considerably to the low temperature side, and the relative dielectric constant at 20 ° C. decreases.

Mn ₃ O ₄ is a fine particle compared to other Mn compounds such as MnO ₂ , and has excellent dispersibility when mixed with other inorganic additives. The reducibility can be improved, and the deterioration of the insulation resistance can be prevented. Further, when Mn is added, the relative permittivity tends to decrease, but Mn ₃ O ₄ has an effect of reducing the tendency as compared with the case where another Mn compound is used.

In terms of Mn ₃ O ₄ , in terms of 1/3 Mn ₃ O ₄ , when α <0.001 mol, sufficient insulation resistance cannot be obtained, and when α> 0.05 mol, the insulation resistance and the specific resistance The dielectric constant tends to decrease.

Y ₂ O ₃ and Dy ₂ O ₃ have an effect of increasing the relative dielectric constant as compared with other rare earth elements. Y ₂
O ₃ and Dy ₂ O ₃ are different from other rare earth elements because
The point is that a higher relative dielectric constant can be obtained by combining with the addition of O. In the case of no addition, it does not promote the grain growth of the dielectric and tends to have a low dielectric constant as well as a low insulation resistance. On the other hand, if it is added in excess of 0.015 mol, the sinterability is reduced and the relative dielectric constant is lowered. The same effects can be obtained when these effects are added alone or in combination. In the case of adding in combination, a higher relative dielectric constant can be obtained by reducing the amount of Dy ₂ O ₃ added than the amount of Y ₂ O ₃ added.

Further, CaCO ₃ , Mn ₃ O ₄ , Y ₂ O ₃ , D
When the powder particle size of y ₂ O ₃ is large or the dispersibility at the time of mixing is poor, the insulation resistance tends to decrease. Therefore, it is necessary to use a powder having a specific surface area of 5 m ² / g or more. In particular, when used for a large-capacity multilayer ceramic capacitor in which the thickness between the internal electrode layers 2 is as thin as several μm to several tens of μm, the insulation resistance is likely to be deteriorated, and a specific surface area of 10 m ² / g or more is used. preferable.

The ternary glass of BaO—Al ₂ O ₃ —SiO ₂ has the effect of improving the sinterability of the dielectric layer 1. It is preferable to use one having a specific surface area of 1 m ² / g or more. When the main component (formula 3) is 100% by weight, adding 0.01% by weight or more to the main component improves sinterability and obtains a high dielectric constant.

[0036]

Embedded image

However, if it exceeds 0.5% by weight,
It is not preferable because insulation resistance is lowered. SiO_TwoAnd Al_TwoO_ThreeTo
Sinterability can also be improved by adding it alone
However, in the case of this composition system, a sufficient relative dielectric constant can be obtained.
Absent. In addition, when the laminate is fired in a large amount,
When other glass materials are used as sintering aids,
In some cases, the lime may adhere through the glass.
O-Al_TwoO_Three-SiO _TwoTernary glass is relatively small
Is less likely to contribute as a sintering aid
No.

Further, the ternary glass composition of BaO—Al ₂ O ₃ —SiO ₂ is such that BaO is 10 to 40% by weight, Al ₂ O ₃
There 1-15 wt%, as long as the SiO ₂ is produced by a composition ratio range of total 100 weight percent of 45 to 89 wt% sufficient dielectric constant, insulation resistance can be obtained. In particular, BaO is 25
A dielectric constant exceeding 15,000 can be obtained in the range of ４０40% by weight, Al ₂ O _{3 of 3} to 10% by weight and SiO ₂ of 50 to 72% by weight.

From the above results, it is possible to produce a multilayer ceramic capacitor having a high dielectric constant, a small dielectric loss, and a sufficiently high insulation resistance only in the composition range of the present invention.

Next, an experiment was conducted in which the ratio of (Ba + Ca) to (Ti + Zr) was changed. At this time, Mn ₃ O ₄ is 1
/ ₃ Mn ₃ O ₄ as 0.015 mol, Y ₂ O ₃ as 0.0
1 mol, the evaluation of the BaO-Al ₂ O ₃ -SiO ₂ three-component glass was added 0.1 wt% to prepare a multilayer ceramic capacitor in the same procedure characteristics was performed. The results are shown in (Table 3).

[0041]

[Table 3]

As is clear from Table 3, within the range of the present invention, the relative permittivity, the dielectric loss, and the insulation resistance show practically sufficient values. On the other hand, No. out of the range. 00
In the case of Sample No. 1, the insulation resistance was low. 005 has poor sinterability and low relative dielectric constant. (Table 3) shows Mn
The results obtained by fixing the addition amounts of ₃ O ₄ and Y ₂ O ₃ are shown, but (Ba) in other dielectric compositions within the scope of the present invention is shown.
The relationship between the (+ Ca) / (Ti + Zr) ratio and the characteristics showed a similar tendency. From the above results, (Ba + Ca) / (Ti +
Zr) when the ratio is 1.00 to 1.02, the dielectric constant is high,
Particularly, a range of 1.00 to 1.01 is desirable.

Hereinafter, the points of the present invention will be described.

(1) In the present embodiment, BaCO ₃ , CaCO ₃ , TiO ₂ ,
Although ZrO ₂ , Y ₂ O ₃ , Dy ₂ O ₃ , and Mn ₃ O ₄ were used, a compound such as BaTiO ₃ or a carbonate or a hydroxide was heated in the air such as a hydroxide so that a desired composition ratio was obtained. Ba
_{O, CaO, TiO 2, ZrO} 2, Y 2 O 3 and Dy ₂ O ₃
Even when a compound that becomes the same is used, characteristics similar to those of the present embodiment can be obtained.

Ba and Ti as main components are made of BaTi.
By adding the compound of O ₃ , Tan δ can be improved. The reason for this is that the crystallinity of BaTiO ₃ , which is the main component of the dielectric layer 1, is improved, and the variation in the particle size is reduced. Therefore, BaTi
O ₃ is most preferably formed by the oxalate method, and then preferably formed by the sol-gel method and subsequently by the solid phase method. In addition, powders were used as starting materials, but Y ₂ O _3, Dy ₂ O ₃ , and Mn ₃ O _{4 serving as} subcomponents were used.
May be added as a liquid in order to improve dispersibility.

Furthermore, when barium titanate is used as a starting material, the specific surface area of the subcomponents of CaCO ₃ , Mn ₃ O ₄ , Y ₂ O ₃ and Dy ₂ O ₃ is larger than that of barium titanate. By doing so, the reactivity between the main component barium titanate and the auxiliary component is improved, and the insulation resistance is improved. Specifically, the specific surface area of barium titanate is 3 m ² /
g or more, and the specific surface area of the subcomponent of CaCO ₃ , Mn ₃ O ₄ , Y ₂ O ₃ and Dy ₂ O ₃ is preferably 5 m ² / g or more.

(2) Although Ni is used for the internal electrode layer 2, any metal containing Ni, such as Ni—Cu, having a melting point higher than the firing temperature of the dielectric layer 1 may be used. Can be used as Specifically, 1350
C. or higher is preferred.

[0048] (3) In addition to binder removal, but also performed to secure the firing conditions, binder removal step may be optimally chosen heat treatment conditions in accordance with the combustion temperature of the organic binder to be used, the firing step N ₂ The atmosphere is not limited to firing in + H ₂ , but may be any atmosphere in which the dielectric layer 1 is not reduced and the internal electrode layer 2 is not excessively oxidized, that is, an atmosphere which can be fired so as to function as the internal electrode layer 2. However,
When firing a large number of laminates at once, the binder in the laminates may not be completely decomposed in the binder removal step. If the undecomposed binder remains during the sintering of the dielectric layer 1, the binder may reduce the dielectric layer 1 or cause a structural defect.

Therefore, in the firing step, the temperature increase is temporarily stopped in a temperature range not lower than the binder decomposition temperature and lower than the sintering start temperature of the dielectric layer 1, and a holding process at this temperature is provided, so that the residual It is desirable to decompose organic matter. In particular,
In the vicinity of the maximum temperature during firing, the equilibrium oxygen partial pressure of Ni is 1
When the oxygen partial pressure is as low as / 20 to 1/10000, sufficient relative dielectric constant and insulation resistance can be obtained. However, firing at an oxygen partial pressure lower than 1 / 10,000 of the equilibrium oxygen partial pressure may reduce the dielectric layer 1 and lower the insulation resistance. At this time, the insulation resistance can be recovered by performing a heat treatment in an atmosphere at or above the equilibrium oxygen partial pressure of Ni after the firing temperature lowering step or after the firing. The maximum temperature during firing is 1
A sufficient relative dielectric constant can be obtained at a temperature in the range of 250C to 1350C.

(4) Conventionally, a dielectric ceramic composition has often been formed using a glass containing Li in order to enhance sinterability. However, Li may be scattered during calcination or firing and accumulate in the firing furnace, and may contaminate the firing furnace. In addition, it is not preferable to use a glass containing Li, since Li attached in the firing furnace may be re-adhered to the sintered body during firing. Further, when firing in a large amount, the scattering state of Li is different between the surface portion and the inside, and there is a possibility that the characteristics may vary. In addition, if structural defects such as voids are induced in the portion where Li is scattered, a defect occurs in characteristics. In the present invention, since Li which may cause a problem is not contained, the dielectric ceramic composition having very excellent characteristics without the possibility of the above problem can be obtained.

(5) In the present embodiment, BaCO
₃ , CaCO ₃ , TiO ₂ , ZrO ₂ , Y ₂ O ₃ , Mn ₃ O ₄ ,
When mixing Dy ₂ O ₃ , BaO—Al ₂ O ₃ —SiO ₂ ternary glass was mixed together, but BaCO ₃ , CaC
O ₃ , TiO ₂ , ZrO ₂ , Y ₂ O ₃ , Mn ₃ O ₄ , Dy ₂ O ₃
It can be added and mixed three-component glass BaO-Al ₂ O ₃ -SiO ₂ to during pulverization after calcination to obtain the same effect as described above.

(6) Since the amount of Mn that causes a decrease in the dielectric constant is small as compared with the prior art and the original dielectric constant of the dielectric ceramic composition of the present invention is high, the Curie point is lowered to the low temperature side. Even if it is shifted, the decrease due to the deterioration of the capacitance over time is small. Therefore, even if the dielectric layer 1 is made thinner and more highly laminated, a multilayer ceramic capacitor with less deterioration of the capacitance with time is obtained.

(7) In this embodiment, a multilayer ceramic capacitor was manufactured and the characteristics of the dielectric ceramic composition were evaluated. The dielectric ceramic composition of the present invention can be used for a single-plate type ceramic capacitor. Needless to say.

[0054]

As described above, the dielectric porcelain composition of the present invention has a high relative dielectric constant, a small change with time in dielectric loss and capacitance, and exhibits excellent insulation resistance even in a reducing atmosphere. It is very effective in producing a multilayer ceramic capacitor having internal electrodes as a main component. Further, since the relative dielectric constant is high, it is very easy to reduce the size and increase the capacity of the multilayer ceramic capacitor. Furthermore, multilayer ceramic conditioner
Large amounts of laminates were stacked and fired to produce sensors
Even if the laminated body adheres to each other via glass
can do.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional perspective view of a multilayer ceramic capacitor according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 dielectric layer 2 internal electrode layer 3 external electrode

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Katsuyuki Miura 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-10-36170 (JP, A) JP-A-8-59344 (JP, A) JP-A-63-134559 (JP, A) JP-A-11-130331 (JP, A) JP-A-10-50549 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/42-35/49 CA (STN) REGISTRY (STN)

Claims (4)

(57) [Claims] 1. A dielectric ceramic composition represented by the following chemical formula (1) . Embedded image 2. A laminate comprising alternately laminated dielectric layers and internal electrode layers, and an external electrode provided on an exposed end face of the internal electrode layer of the laminate, wherein the dielectric layer comprises 1)
A multilayer ceramic capacitor formed using the dielectric ceramic composition represented by 3. The multilayer ceramic capacitor according to claim 2, wherein a metal mainly composed of Ni is used for the internal electrode layer. 4. A first step of alternately laminating a green sheet formed by using a dielectric material and an internal electrode paste containing Ni as a main component to form a laminate, and then, laminating the laminate. A method for manufacturing a multilayer ceramic capacitor, comprising: a second step of performing a heat treatment at a temperature lower than a temperature at which a green sheet starts to be sintered; and a third step of firing the laminate in a reducing atmosphere at a temperature lower than the melting point of Ni. At
A method for manufacturing a multilayer ceramic capacitor, wherein the dielectric material has a composition represented by (Chemical Formula 1).