JPH02296313A - Dielectric porcelain composition and laminated ceramic capacitor using same, and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to ceramic capacitors used in electronic devices, particularly dielectric ceramic compositions for laminated ceramic capacitors having internal electrodes made of nickel, and dielectric ceramic compositions thereof. The present invention relates to a multilayer ceramic capacitor using the composition and a method for manufacturing the same.

Conventional Multilayer Ceramic Capacitors are composed of layers of electrodes and dielectric ceramic compositions, and are integrated and solidified using ceramic manufacturing technology, making it possible to obtain small capacitors with large capacity. Furthermore, since the electrode is built-in, there is little magnetic induction component, and it exhibits excellent performance even in bright frequency applications. Also,
The chip type does not have lead wires, so it can be directly attached when mounting components, and it meets the demand for smaller and lighter electronic devices.
Further development is expected in the future.

On the other hand, based on the classification of capacitor materials, aluminum electrolytic, tanker electrolytic 1 paper, and organic film are listed, and the capacity range of multilayer ceramic capacitors puts them in a competitive relationship with all of them. Therefore, future demands for multilayer ceramic capacitors are higher capacity, smaller size, and lower cost. The capacitance of a multilayer ceramic capacitor can generally be expressed by the following formula.

C=EEX-Xn Eo: Permittivity of vacuum ES: Relative permittivity of dielectric material n: Number of stacked layers S: Electrode area d Dielectric thickness per knee layer As is clear from the above, efforts are being made to increase the dielectric constant of dielectric materials, increase the number of laminated layers in order to increase the electrode area, and reduce the thickness of dielectric layers.

For miniaturization, the chip shape is 3.2mm x 1.6
mm to 2.0 mm x 1.25 mm or 1.6 mm x
018+nm.

Furthermore, efforts are being made to achieve 1.0 mm x 15 mm. The next step is to reduce the cost to 1, which is the biggest requirement. This is because larger capacity and smaller size
This is not a requirement that conflicts with cost reduction, but rather an issue that should be tackled simultaneously with increasing capacity and downsizing.

A conventional multilayer ceramic capacitor uses BaTiO3 as a main component of the dielectric material, and uses noble metals P and d for internal electrodes. Therefore, the ratio of internal electrode material cost to production cost is extremely high, and is said to be more than 7 harms. In particular, products with large capacitance have a large number of internal electrodes, which further increases costs.Despite the fact that multilayer ceramic capacitors have high capacitance efficiency, other excellent dielectric properties, and high reliability, the price is still low. This was a major hindrance.

Various studies are being conducted in various fields with the aim of reducing these costs by 1 or less. Among these, a method of using Ag--Pd as an internal electrode material is being considered, focusing on Ag, which is relatively inexpensive among noble metals.

(For example, in JP-A-49-19399, S, 5u
bbrao: J Pbys, Cbem.

5olicls, 236.65 (1962)) On the other hand,
Considering that even Ag is expensive, there is a trend toward using base metals. In other words, Ni is used as the electrode material. When a base metal such as Ni is used as an internal electrode, Ba
The TiO3-based dielectric and the base metal internal electrode must be co-fired in a non-oxidizing atmosphere in which nickel is not oxidized. However, in this case, conventional BaTiO3
Alternatively, the dielectric material made of the solid solution is easily reduced and loses its insulating properties, resulting in the drawback that practical dielectric properties cannot be obtained as a multilayer ceramic capacitor. Therefore, non-reducible ceramic dielectric materials are being developed as materials that are not reduced even when fired in a neutral or reducing atmosphere.

(For example, JP-A-55-67568, JP-A-61-
256968, JP-A-60-109104, etc. ) Next, in the manufacturing method of multilayer ceramic capacitors using Ni as internal electrodes, generally the internal electrodes (N
An unsintered laminate consisting of multiple layers of dielectric Green Sea 1-, which is coated with i) and whose main component is BaTiO3, is sintered in a nitrogen atmosphere with an extremely low oxygen partial pressure so that the Ni in the internal electrodes is not oxidized. It is manufactured by bonding and integrating.

Problems to be Solved by the Invention The present invention aims to produce a multilayer ceramic capacitor with internal electrodes of Ni. The present invention provides a dielectric ceramic composition having a low dielectric loss tangent and a low dielectric loss tangent.

Next, the present invention provides a new manufacturing method that solves the problems of the conventional manufacturing method of multilayer ceramic capacitors using Ni as internal electrodes.

In conventional manufacturing methods, it is difficult to use an organic binder when co-firing the internal electrodes and the dielectric material. In other words, it is difficult to completely remove the organic binder used in the dielectric Green Sea I. and the same organic binder contained in the electrode paste in a non-oxidizing atmosphere. If the dielectric material cannot be completely removed, it is said that the dielectric material itself remains porous, which not only prevents sintering but also results in a blackened material due to the decomposed carbon. This problem arises when the organic component content in the sheet increases due to an increase in the number of laminated layers due to the increase in the capacity of multilayer ceramic capacitors, or due to the pulverization of dielectric powder due to low temperature firing. It is expected that this will become an important issue in the future.

Means for Solving the Problems The dielectric ceramic composition of the present invention is (Bam(Tx, -xZrx)Oz+m) + ---
Ten (Senwa02) + (Nto) + (×
) X is at least one of Yb2O3, Dy2o3ThO2, m, x, α, β
, γ is in the following range.

0.98≦m≦1.02 0≦X≦0.2 0.005≦α≦0. O5 o, o ol ≦β≦0.02 0.001≦T≦0.02 Further, the method for manufacturing a multilayer ceramic condenser of the present invention includes the dielectric composition described in “2” and at least an organic binder,
A step of forming a patterned film by printing paste 1, which is made of nickel oxide as a main component and kneaded with a vehicle comprising at least an organic binder and an organic solvent, on a green sheet made of a solvent and a plasticizer; a step of laminating a desired number of green sheets by heating and pressurizing them; a step of cutting the thus laminated laminate into desired dimensions; The organic binder is heated in air at a temperature at which it does not start to harden, and the organic binder is burned, and the organic binder is heat-treated in a reducing atmosphere.
The special feature is that it consists of a process of reducing the nickel oxide to metal, and a process of firing this in a nitrogen atmosphere at a temperature lower than the melting point of nickel to densify the dielectric ceramic composition and the metal. That is.

Function Since the dielectric ceramic composition of the present invention contains MnO3, it has the effect of suppressing the conversion of barium titanate (BaTiO2) into a semiconductor by firing under a low oxygen partial pressure by charge compensation. This results in good insulation resistance even during firing under low oxygen partial pressure. Furthermore, Y, b203, is extremely stable (hard to reduce) even under low oxygen partial pressure.
．． By including D3+208The2, etc., there is no effect on insulation properties, and :l, :, Yb,, 03.
Dy2O3°The2 and the like have a function of promoting grain growth of the dielectric material during firing under low oxygen partial pressure, and are therefore effective in increasing the dielectric constant. Furthermore, the addition of NiO lowers the dielectric loss tangent and lowers the sintering temperature of the dielectric, which is very effective in obtaining a dense sintered body, thereby improving reliability such as moisture resistance. - It has the effect of causing From the above two points, the dielectric ceramic composition of the present invention has excellent insulating properties, and also has a high dielectric constant and low dielectric loss tangent, making it extremely effective for realizing multilayer ceramic capacitors using Ni as internal electrodes. be.

Next, the method for manufacturing a multilayer ceramic capacitor of the present invention makes it possible to completely remove the organic binder, which was the biggest problem. Furthermore, since nickel oxide was used as the starting material for the internal electrodes, only the decomposition and removal of the organic binder was considered during the binder process, and only the densification of the dielectric layer and the electrode layer reduced to Ni during sintering. It is now possible to manufacture highly reliable multilayer ceramic capacitors without having to perform delicate atmosphere control such as removing the organic binder without oxidizing the electrodes, as required in the past.

Example Next, the present invention will be explained based on one embodiment.

First, BaTiO3 and BaZr(]+ were synthesized by calcination method.BaTiO3, reagents B a C03 and Ti
After wet mixing with O2 in a ball mill,
It was calcined at 0''C for 2 hours, then wet-pulverized in a ball mill and dried before use. BaZrO3 was prepared using the reagents BaCO3 and ZrO, following the same procedure as the BaTiO3 synthesis. .

The average particle size of each of the synthesized powders of BaTiO3 and BaZrO3 was about 1 μm. Next, MnO,, M of the reagent
The nO2 was wet milled in a ball mill to an average particle size of about 1.
A sample with a thickness of 5 μm was used.

The NiO reagent was calcined in air at 1300° C. for 2 hours, wet-pulverized in a ball mill, and had an average particle size of about 1 μm.

BaTi0,3゜Ba'Zr03 prepared in this way
Mno, , NiO and Yb203Dy203. Th02
The inorganic component is at least one of these weighed in the proportion shown in Table 1, and further contains polyvinyl butyral resin as an organic binder, BBP (henzyl butyl phthalate-1i) as a plasticizer, toluene as an i agent, Ethanol was added and mixed in a ball mill to prepare a slurry.The solvent used was a mixture of toluene and ethanol in a weight ratio of 3:2.After degassing this slurry in a vacuum, it was mixed using a doctor blade method. A green sheet was prepared by forming a film.The thickness of the green sheet after drying was approximately 40 μm.Next, nickel oxide (NIP) powder with an average particle size of 1.5 μm was deposited on the green sheet. Using this paste, screen printing was performed to obtain the desired pattern.

The conditions for preparing the paste were as follows: ethyl cellulose as an organic binder was dissolved in turpentine oil as a solvent, and the paste was kneaded with the above nickel oxide powder using a three-stage roll. Twenty Green Seas 1 to 1 with electrode patterns obtained as described above were stacked one on top of the other so that the internal electrode patterns faced each other, and were bonded together by thermocompression. Then, the unsintered laminate was further cut into a size of 4 mm x trivalent to prepare an unsintered laminate. First, the binder from this unsintered laminate is removed. The post-binder removal step was carried out by heat treatment in air at 700°C for 2 hours (temperature increase/decrease 100°C/h). This step aims at removing the organic binder component contained in Green Sea 1~ and the nickel oxide paste. When the element body after the binder was removed was observed with a scanning electron microscope, no progress of sintering of the dielectric layer was observed. Furthermore, compositional analysis revealed no presence of carbon in the element, confirming that organic components were sufficiently removed. Next, the internal electrodes of this binder-removed element body are reduced.

This step was carried out at 250° C. for 2 hours in an atmosphere of 100% hydrogen. This step does not reduce the components of the dielectric layer, but only the nickel oxide of the internal electrodes is reduced to metallic nickel. Next, the reduced element body is fired. Firing at 1250°C for 2 hours (elevating 1A200"c,'h)
I did it. The firing atmosphere was adjusted by using N2 gas as a carrier gas and controlling the flow rate of green gas so that the oxygen concentration in the electric furnace was 10'9 atm in a temperature range of 500''C or higher. A commercially available Cu paste for firing in a nitrogen atmosphere at 900°C was applied as an external electrode to the end face of the obtained sintered body, and baked in a mesh-type continuous belt furnace to obtain a sample for measuring characteristics.

The capacitance and dielectric loss tangent were measured at a frequency of 1.0 KHz, an input signal level of l, and Q Vrms, and a relative permittivity was calculated from the capacitance. Thereafter, a DC voltage of 50 V was applied for 1 minute, and the insulation resistance at that time was measured. Note that the thickness of the dielectric layer was about 257 zm and the thickness of the electrode layer was 3 to 4 μm.

The above measurement results are also shown in Table 1. Note that the measurement was performed in a constant temperature bath at 25°C.

(Left below) As is clear from the first vote, the laminated ceramic capacitor produced using the dielectric ceramic composition of the present invention has a high dielectric constant, and has a practical dielectric loss tangent and insulation resistance. It showed a sufficient value. The relative dielectric constant of this example may be a little low depending on the dielectric composition, but the components such as Zr component, Mn component, Ni component, Yb, Dy, and Th in the dielectric composition act as shifters, and the Curie point This shows that the Curie point is not necessarily at the optimal position in order to move. However, by optimally adjusting the above components within the scope of the present invention, it is possible to increase the dielectric constant at 25°C. On the other hand, although the insulation resistance varies depending on the dielectric composition, it shows a practically sufficient value for any dielectric composition. Further, when paying attention to the dielectric loss tangent (La nδ), it decreases as the amount of NiO added increases, so NiO is a very effective additive for lowering the dielectric loss tangent.

Next, the results of a similar experiment conducted using a multilayer ceramic capacitor manufactured using a dielectric ceramic composition other than the scope of the present invention will be described. First, with regard to Mn0z, when no additive is used or the amount is less than 0.5 mol %, sufficient insulation resistance cannot be obtained, and when the amount exceeds 5 mol %, the insulation resistance tends to decrease. Also, Yb2O3, Dy2O
3. When additives such as ThO2 are not added, they do not promote dielectric grain growth and have no effect of increasing the relative permittivity, and when added in an amount exceeding the range of the present invention, they cause extremely high sinterability. The results showed that it got worse. In addition, when the Zr component was set beyond the range of the present invention, the Curie point moved too far to the low temperature side, and a multilayer ceramic capacitor with a high dielectric constant could not be obtained. Furthermore, Table 2 shows the characteristics of the multilayer ceramic capacitor manufactured using the dielectric composition without adding NiO. The sample preparation method used the procedure described above in this example.

(Left below) When comparing the characteristics shown in Table 2 with the characteristics shown in Table 1, especially the dielectric loss tangent (tan δ), it is clearly seen that the addition of NtO is effective. From the above two results, within the composition range of the present invention, it is possible to manufacture a multilayer ceramic capacitor with a commercial dielectric constant, a small dielectric loss tangent, and a sufficient insulation resistance.

Next, an experiment was conducted in which the ratio of Ba and Ti+Zr was changed.

The ratio of Ba and Tt+Zr is
The mixing ratio of CO3 and TiO2 was changed.

Furthermore, the BaZrO3 component is 10 mo1%, MnO,.

A multilayer ceramic capacitor was manufactured in the same manner using 2 mo1% of NiO, 0.5 mo1% of NiO, and 0.5 mo1% of Dy2O3, and its characteristics were evaluated.

The results are shown in Table 3.

(Margin below) Table 3 As is clear from Table 3, the samples within the scope of the present invention exhibit very excellent properties in terms of relative dielectric constant, dielectric loss tangent, and insulation resistance. On the other hand, sample A outside the range had low insulation resistance, and sample G had poor sinterability and low dielectric constant despite containing NiO.

The results shown in Table 3 are based on BaZrO3, MnO2, Ni
The experiments were carried out by fixing the addition amounts of p and Dy2O3, but the Ba/Ti+Zr ratio showed a similar influence on the characteristics even in dielectric compositions within the range of the present invention. From the above results, B
The a/Ti+Zr ratio is preferably in the range of <0.98 to 1.02 as shown in claim 1 of the present invention.

In this example, BaTiO in the dielectric ceramic composition
3.BaZrO3 was produced by the calcination method, but 14! There is no problem even if the product is prepared in advance, and good results can be obtained.

In addition, in this example, the conditions for each step of binder removal 1 reduction and firing were fixed, but the conditions for the binder removal step were as follows.
It is only necessary to select the optimal one according to the type of organic binder used, and the conditions in the reduction process are sufficient as long as the dielectric is not reduced and only the nickel oxide of the electrode is reduced, and the atmosphere must be 100% H2. It doesn't have to be the atmosphere. Furthermore, the atmosphere of the firing process is not limited to the conditions of this example, but as long as the oxygen concentration is below the equilibrium oxygen partial pressure of Ni and NiO at the holding temperature during firing (1250°C in this example). If the Ni electrode is not significantly oxidized in other temperature increasing and decreasing temperature regions, N1 and NiO
There is no problem even if the atmosphere contains oxygen at a level higher than the equilibrium oxygen partial pressure.

Further, in this example, a multilayer ceramic capacitor was manufactured and the characteristics of the dielectric ceramic composition were measured. However, it goes without saying that the dielectric ceramic composition of the present invention can be used in a single-plate ceramic capacitor. do not have. Furthermore, by using the manufacturing method of the present invention, application to multilayer wiring boards with built-in multilayer varistors and capacitors becomes possible.

Effects of the Invention The dielectric ceramic composition within the scope of the claims of the present invention exhibits low insulation resistance even when fired under an extremely low oxygen partial pressure, has a high dielectric constant near room temperature, and has a low dielectric loss tangent. Therefore, it is very effective in producing a multilayer ceramic capacitor using Ni as an internal electrode. Furthermore, since the method for manufacturing a multilayer ceramic capacitor of the present invention performs binder removal in air, a special organic binder is not required and the binder can be completely removed. Furthermore, since it is easier to control the atmosphere during reduction and firing, it is extremely effective to use base metals for the internal electrodes of multilayer ceramic capacitors. This invention is extremely flexible when aiming to increase capacity by increasing the number of layers and increasing the number of layers.

Name of agent: Patent attorney Shigetaka Awano, 1-person procedural amendment (master) 2. Title of invention Related to the case Address Name: Representative Patent Applicant: Matsushita Electric, 1006 (582) Oaza Kadoma, Kadoma City, Osaka Prefecture Akio Tanii Sangyo Co., Ltd. 4 Agent Address: 1006 Oaza Kadoma, Kadoma City, Osaka 571 Matsushita Electric Industrial Co., Ltd. 5 Claims column 6 of the specification subject to the amendment, Contents of the amendment (1) Specification The claims of the book are amended and deleted as shown in the attached sheet.

(2) "Represented by the present invention" on page 8, lines 11 to 14 of the specification is amended as follows.

“The dielectric ceramic composition of the present invention has the following properties: (Bam(T11-, Zrx)02+m)1-α-β-
4+(M no 2 ) α+(N 10 ) 19
+ (represented by X 1 r) 2.Claim (1) In the compositional formula, x is
At least one or more of the following: m, x.

A dielectric ceramic composition characterized in that α, β, and γ are in the following ranges.

o, 9s-z: m=1. o 2 o y= x /: 0.2 0.005-' (t -'0.05 0.001-'β-'0.02 0.001i γ-'0.02 (2) Claim ( 1) A ceramic capacitor comprising the dielectric ceramic composition described above.

(3) A multilayer ceramic capacitor comprising a dielectric layer made of the dielectric ceramic composition according to claim (1) and an internal electrode layer containing Ni as a main component.

(4) Grid 2 consisting of the dielectric ceramic composition according to claim (1) and at least an organic binder, a solvent, and a plasticizer.
- A process of printing a paste made of nickel oxide as a main component and kneading it with a vehicle consisting of at least an organic binder and an organic solvent on the green sheet to form a pattern film, and applying the printed green sheet to the desired number of sheets. A step of laminating the layers by applying heat and pressure, a step of cutting the thus laminated layered product into desired dimensions, and a step of heating this in air at a temperature at which the dielectric ceramic composition does not begin to sinter. , a step of burning the organic binder, a step of heat treating it in a reducing atmosphere to reduce the nickel oxide to metal, and a step of firing it in a nitrogen atmosphere at a temperature lower than the melting point of nickel to form a dielectric material. A method for manufacturing a multilayer ceramic capacitor, comprising a step of densifying a ceramic composition and a metal.

Claims (4)

[Claims] (1) Composition formula {Bam(Ti_1_-_XZr_X)O_2_+_m
}_1_-- − +{MnO_2}+{Nio}+{
x}, where X is Yb_2O_3, Dy_2O_3,
Consisting of at least one type of Tho_2, m, x
, α, β, and γ are in the following ranges. 0.98≦m≦1.02 0≦x≦0.2 0.005≦α≦0.05 0.001≦β≦0.02 0.001≦γ≦0.02 (2) A ceramic capacitor comprising the dielectric ceramic composition according to claim (1). (3) A multilayer ceramic capacitor comprising a dielectric layer made of the dielectric ceramic composition according to claim (1) and an internal electrode layer containing Ni as a main component. (4) A vehicle comprising a nickel oxide as a main component and at least an organic binder and an organic solvent on a green sheet comprising the dielectric ceramic composition according to claim (1), at least an organic binder, a solvent, and a plasticizer. A process of printing the paste kneaded with the above to form a pattern film, a process of laminating a desired number of the printed green sheets by heating and pressurizing them, and a process of forming the thus laminated laminate into desired dimensions. cutting the dielectric ceramic composition, heating it in air at a temperature at which the dielectric ceramic composition does not begin to sinter;
Dielectric porcelain is produced by burning the organic binder, heat-treating it in a reducing atmosphere to reduce the nickel oxide to metal, and firing it in a nitrogen atmosphere at a temperature lower than the melting point of nickel. A method for manufacturing a multilayer ceramic capacitor, comprising a step of densifying a composition and a metal.