JPH0650702B2 - Paste composition and method for manufacturing laminated ceramic capacitor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a ceramic laminate and a conductor paste composition for application thereto. Examples of the ceramic laminated body include a laminated ceramic capacitor.

2. Description of the Related Art The following three types of ceramic laminated bodies are typical when classified according to the function of the ceramic material. The first is a ceramic multi-layer substrate that utilizes the insulating properties of ceramic materials, and the second is a laminated ceramic capacitor that utilizes the dielectric properties, and a chip coil that utilizes the magnetic properties. In particular, what has been attracting attention in recent years is the application to multilayer ceramic capacitors.

A monolithic ceramic capacitor is one in which electrodes and a dielectric porcelain composition are layered, and since they are integrated and solidified by a ceramics manufacturing technique, a small size and large capacity can be obtained. Furthermore, since the electrodes are built-in, it has few magnetic induction components and exhibits excellent performance in high frequency applications.

In addition, the chip type does not have lead wires, so it can be directly mounted when mounting components, and it meets the demand for smaller and lighter electronic devices, and further development is expected in the future.

On the other hand, as electrode materials used for these laminated bodies, Au,
Noble metals such as Pt and Pd and base metals such as W, Ni and Cu are often used. In particular, a ceramic substrate is one in which an organic binder and a solvent are added to this metal material to form a paste, which is screen-printed on an insulating substrate such as alumina and baked to form a conductor pattern. Further, in the ceramic multilayer substrate, in addition to these conductor pastes, a method of forming a multilayer by using ceramics or glass powder as an insulating material dispersed in a solvent in which an organic binder is dissolved, and the above-mentioned insulating powder and organic binder are used. There is a method of laminating a pattern formed of the conductor paste on a green sheet made of, for example, to form a multilayer. Focusing on the metal conductor materials used for these, Au and Ag / Pd can be fired in the air, but are expensive because they are noble metals. On the other hand, W, Ni, and Cu are base metals and inexpensive, but the firing atmosphere must be a reducing atmosphere or a neutral atmosphere.

Further, W and Mo are fired at a high temperature of 1500 ° C or higher. Further, from the viewpoint of reliability, solder erosion becomes a problem with Au,
Ag / Pd has a problem of high migration and high conductor resistance. In order to use Cu, it is necessary to perform firing in a neutral atmosphere such as nitrogen, and it is also necessary to sinter the ceramic material at a melting point of Cu or lower. There are limits to the ceramic materials that can be used. Therefore, Ni is used as the electrode material and BaT is used as the dielectric material.
multilayer ceramic capacitor using the iO ₃ has been proposed. For example, Japanese Patent Laid-Open Nos. 55-67568 and 6
No. 1-256968, JP-A-60-109104. However, there are problems in using Ni. It is N
This is because firing of the multilayer capacitor with the i-electrode creates a reducing atmosphere, and it becomes difficult to decompose and remove the organic binder in the paste. This is because the oxygen concentration in nitrogen is low, so that the binder does not decompose and remains in the form of carbon, which adversely affects the metallization performance. On the contrary, when the oxygen concentration is high, the Ni electrode is oxidized and diffuses in the dielectric, and the Ni electrode does not function as an electrode. Therefore, firing is required to supply while controlling a slight amount of hydrogen and oxygen in a nitrogen atmosphere.

Then, it becomes difficult to remove the organic binder contained in the green sheet such as a dielectric, and if the removal is not complete, the binder remains carbonized and causes a blister between the layers, or does not match the electrode-dielectric. It becomes a factor to make it worse.

Therefore, a method has been proposed in which the binder removal and the Ni metallization are compatible. In this method, nickel oxide is used as a starting material for the electrode. According to this method, a heat treatment for binder removal is performed in air in advance, then nickel oxide is reduced to metallic Ni, and then firing is performed in nitrogen. It is a thing. This method is the most suitable method for obtaining a laminated body of Ni electrodes because binder removal is performed in advance and reduction and firing are performed. The layering method using nickel oxide is described in Japanese Patent Application No. 59-269011, and the nickel oxide paste is described in Japanese Patent Application No. 60-134546.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, with the above-described configuration, the following problems to be solved have become clear. This is because in the ceramic laminate as described above, the matching property between the ceramic material and the nickel oxide paste during firing differs depending on the composition of the ceramic material. Therefore, the composition of the nickel oxide paste must be selected according to the ceramic material to be laminated. However, in the conventional nickel oxide paste, cracks and delamination occur during firing,
In addition, the electrode metallization has a problem.

In view of the above problems, the present invention provides a nickel oxide paste which has good matching properties with a ceramic material for producing a ceramic laminate and is excellent in metallizing performance, and a method for producing a ceramic laminate using the same.

Means for Solving the Problems In order to solve the above problems, the composition of the nickel oxide paste of the present invention is such that 90.0 to 99.5% by weight of NiO powder and BaTi
O ₃ , MnO ₂ , Ta ₂ O ₅ , CaO, ZrO ₂ , Y ₂
O ₃ , Dy ₂ O ₃ , Yb ₂ O ₃ , and at least one selected from TlO ₂ are contained in an inorganic component containing 0.5 to 10 wt% and an organic vehicle component composed of at least an organic binder and a solvent. The manufacturing method of the laminated body,
Consists of a step of removing the organic binder by heat treatment in air, a step of reducing the internal electrode by heat treatment in hydrogen, and a step of sintering the dielectric and the internal electrode by heat treatment in nitrogen. It was done.

Action The present invention can obtain good matching property with a ceramic material by using the NiO paste having the above-described configuration in forming a ceramic laminate and by the above-mentioned manufacturing method. NiO paste is B in addition to NiO
aTiO ₃ , MnO ₂ , Ta ₂ O ₅ , CaO, Zr
It is constituted by adding an additive selected from O ₂ , Y ₂ O ₃ , Dy ₂ O ₃ , Yb ₂ O ₃ and TlO ₂ . The ceramic laminated body of the present invention is mainly applied to laminated ceramic capacitors and the like.

In general, a substrate material used for a monolithic ceramic capacitor has a melting point of nickel (1455 ° C.) or less, and it is necessary to sinter in a reducing atmosphere. Therefore, an additive that mainly imparts reduction resistance to a BaTiO ₃ dielectric material is added. It is a thing with things added.

That is, a part of BaO substituted with SrO, CaO, MgO, etc., which are the same divalent alkaline earth metal oxides, does not become a semiconductor even when fired under a low oxygen partial pressure, and exhibits excellent electrical insulation properties. That is. The NiO paste of the present invention can enhance the wettability and reactivity with the substrate material by adding the above-mentioned additive to the dielectric material composition of these laminated ceramic capacitors.
Is suitable for integration with the laminate composition.

In addition, the outline of the method for manufacturing the laminate is to form a green laminate of the NiO paste of the present invention and a ceramic material (mainly a green sheet of the ceramic composition and printing with the NiO paste are laminated), and then perform the lamination in air. The binder is removed by heat treatment. This is the reason why NiO is used as the starting material of the conductor. That is, in this step, only the organic binder in the laminated body is removed, and NiO and other additives inside do not cause any reaction or sintering. Next, at low temperature, only NiO is reduced without reducing the ceramic material. (Desirably 2
(Hydrogen atmosphere at 00 to 300 ° C.) Further, the ceramic material and the conductor material are sintered by firing in a nitrogen atmosphere. (Preferably about 1200 to 1300 ° C.) The NiO powder of the conductor layer does not undergo a large sintering reaction during binder removal, but it becomes Ni metal during reduction and undergoes significant volume shrinkage. Therefore, with a conductor composition containing only NiO powder, the shrinkage of Ni is too large, which may cause a gap between the electrode and the ceramic layer or a crack in the ceramic layer. However, the NiO composition of the present invention does not cause the above problems. That is, the additive reacts with the ceramic material in the vicinity of the sintering temperature, and when other additives are added at the same time, the sintering shrinkage of the electrode layer is almost the same as that of the ceramic. As a result, good metallization performance can be obtained. Further, when the total amount of the additives is 0.5% by weight or less with respect to the amount of NiO powder, good metallizing properties cannot be obtained, and conversely 1
When it is 0% by weight or more, the shrinkage of the conductor layer is too small, and the matching property with the sintered body is deteriorated. Desirably, the amount of the additive is 1 to 5% by weight.

Example A multilayer ceramic capacitor according to an example of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a monolithic ceramic capacitor according to the first embodiment of the present invention. In FIG. 1, 1 is a nickel layer for an internal electrode, 2 is a ceramic dielectric material, and 3 is an external electrode C.
It is the u layer. The multilayer ceramic capacitor configured as described above will be described in detail below.

The composition of the dielectric material and the composition of the green sheet are as shown in Table 1.

Dielectric composition {Ba _m (Ti _lx Zr _x ) O _{2 + m} } _{lq-s +} {MnO ₂ } _q + {Dy ₂ O ₃ } _s m = 1.01 x = 0.1 q = 0.02 s = 0.005 First, according to the present invention. Such a dielectric material is based on {Ba _m (Ti _lx Zr _x ) O _{2 + m} }
O ₂ ], {Dy ₂ O ₃ } was used. The average particle size is 1.5 μm, and the dielectric is Ba (Ti,
Zr) O ₃ was prepared (BaO, ZrO ₂ , TiO ₂
Calcination at 200 ° C. ), After which other components were added, and the mixture was calcined again (about 1000 ° C.) and pulverized. This dielectric was used as an inorganic component, polyvinyl butyral as an organic binder, DBP as a plasticizer, and a mixed liquid of toluene and ethanol as a solvent to form a slurry. This slurry was formed into a green sheet by a doctor blade method on an organic film. The film thickness after drying was about 30 μm.

Next, a method for producing the nickel oxide paste will be described.

As the nickel oxide powder, one having an average particle size of 1.0 μm is used. In addition, BaTiO ₃ , MnO ₂ , Ta ₂ O ₅ , CaO, Zr is used.
O ₂ , Y ₂ O ₃ , Dy ₂ O ₃ , Yb ₂ O ₃ and TlO ₂ were used to obtain an inorganic composition as shown in Table 2. Next, as the vehicle composition of the organic component, terpineol was used as a solvent, and ethyl cellulose as a binder was dissolved. This organic vehicle and the above inorganic composition were kneaded with a three-stage roll to form a paste. Table 2 shows the inorganic composition of this nickel oxide paste.

Next, a method of manufacturing the multilayer capacitor will be described.

The NiO paste was screen-printed on the dielectric green sheet to form an internal electrode pattern.
Six green sheets with electrodes formed in the same manner were laminated so as to constitute a counter electrode, and laminated with a hot press at a pressure of 80 ° C.-120 Kg / cm ² .

Then, cutting was performed in consideration of the shrinkage ratio so that the dimension after firing was 1.6 × 3.2 mm. The effective area of the electrode is 2.88 mm ² (1.2
X 2.4 mm), the effective total number of dielectric layers is 5, and the thickness of the dielectric layers is about 20 μm after firing. Next, the unsintered laminate is debindered. The organic binder of the dielectric green sheet and the organic binder in the NiO paste used in this example are butyral resin and ethyl cellulose, respectively. Therefore, in order to decompose and remove by heat treatment in air, a temperature of 300 ° C. or higher is required due to its decomposability. It should be noted that the temperature of the binder removal may be higher than the temperature at which the binder decomposes, but if it is performed at an unnecessarily high temperature, the diffusivity of nickel oxide into the dielectric increases and the dielectric properties deteriorate. Further, the temperature condition of the binder removal should be determined in advance based on the result of the thermal analysis of the organic binder, but as a result of the examination in this example, 300 ° C. to 800 ° C.
The temperature of ° C is good. The holding time in this binder removal step was 2 hours, and the temperature rising / falling speed was 100 (° C./hour).

Next, in the reduction step, hydrogen 1
Each temperature 5 in the range of 100 ° C to 400 ° C in the atmosphere of 00%
I kept it for a while and examined it. As a result (the binder removal temperature is 7
It can be seen that the reduction to (00 ° C.) metallic nickel occurs sufficiently at 150 ° C. or higher. Below that, since nickel oxide remains as it is, it does not function as an electrode and dielectric characteristics cannot be obtained. On the contrary, at 350 ° C. or higher, the dielectric component is reduced and the dielectric becomes gray. If a metal is present in the dielectric, the dielectric properties cannot be obtained. Therefore, the reduction temperature is 150
From 350 to 350 ° C is suitable. Next, the firing process will be described.

The firing was carried out in an atmosphere of nitrogen and hydrogen in a tubular electric furnace. At this time, while monitoring the atmosphere in the tubular furnace with a zirconia oxygen concentration meter, the flow rates of nitrogen and hydrogen were controlled so that the oxygen partial pressure was equal to or lower than the parallel oxygen partial pressure of metallic nickel and nickel oxide.

As a result, good performance was shown at 1200 to 1350 ° C. The multilayer capacitor was evaluated by applying Cu paste for external electrodes to the terminal portion of the multilayer capacitor,
It was carried out by baking in a mesh belt furnace with a holding time of 10 ° C. (in nitrogen) for 10 minutes. The firing atmosphere at this time is 1
The oxygen concentration was ˜2 ppm.

Standard conditions (700 ° C for binder removal, 250 for reduction)
Table 3 shows the evaluation results of the NiO paste at 1250 ° C and firing.

From Table 3, delamination is likely to occur when the content of the additive is 0.5% or less, and effective dielectric properties and matching are obtained when the content is more than 0.5%. On the other hand, if it is 10% or more, delamination is often generated, which is not effective.

As described above, according to the present invention, the NiO powder is 90.0 to 99.5% by weight.
In addition, BaTiO ₃ , MnO ₂ , Ta ₂ O ₅ , CaO, Z
rO ₂ , Y ₂ O ₃ , Dy ₂ O ₃ , Yb ₂ O ₃ , TlO ₂
By using the paste composition containing 0.5 to 10% by weight of at least one selected from the above, it is possible to obtain a good laminate having excellent matching properties with the ceramic material when the ceramic laminate is produced.

In addition, the method for manufacturing a laminate includes a binder removal step by heat treatment in air, a reduction step by heat treatment in hydrogen,
It is composed of a firing process in nitrogen, which makes it possible to easily control the atmosphere and achieve reliable Ni metallization.

This makes it possible to obtain a very good laminated ceramink capacitor.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a monolithic ceramic capacitor according to a first embodiment of the present invention. 1 ... Internal electrode layer, 2 ... Dielectric material, 3 ... External electrode layer.

Claims (6)

[Claims] To 1. A NiO powder from 90.0 to 99.5 _{wt%, BaTiO 3, MnO 2,} Ta 2 O 5, CaO, ZrO
₂ , Y ₂ O ₃ , Dy ₂ O ₃ , Yb ₂ O ₃ , an inorganic component containing 0.5 to 10% by weight of at least one selected from TO ₂ and an organic vehicle component including at least an organic binder and a solvent. A paste composition comprising: 2. A method of manufacturing a laminated ceramic capacitor comprising BaTiO ₃ powder as a main component of a dielectric material, wherein the internal electrode paste composition comprises 90.0-99.5% by weight of NiO powder and B
aTiO ₃ , MnO ₂ , Ta ₂ O ₅ , CaO, Zr
From an inorganic component containing 0.5 to 10% by weight of at least one selected from O ₂ , Y ₂ O ₃ , DyO ₃ , Yb ₂ O ₃ , and TO ₂ , and an organic vehicle component composed of at least an organic binder and a solvent. And a step of removing the organic binder by heat treatment in air, a step of reducing the internal electrode by heat treatment in hydrogen, and a step of sintering the dielectric and the internal electrode by heat treatment in nitrogen. A method of manufacturing a monolithic ceramic capacitor, comprising: 3. The method for producing a monolithic ceramic capacitor according to claim 2, wherein the organic binder is removed in a temperature range of 300 to 800 ° C. 4. The method for producing a monolithic ceramic capacitor according to claim 2, wherein the reduction heat treatment is performed in a temperature range of 150 to 350 ° C. 5. The method for producing a monolithic ceramic capacitor according to claim 2, wherein the firing temperature is in the temperature range of 1150 to 1350 ° C. 6. The composition formula of the dielectric composition is {Ba _m (Ti _lx Zr _x ) O.
_2-m } _{lq-s +} {MnO ₂ } _q + {X} _s , where X is Yb ₂ O ₃ , D
The method for producing a monolithic ceramic capacitor according to claim (2), which comprises at least one of y ₂ O ₃ and TO ₂ and m, x, q, and s are in the following ranges. 0.98 ≤ m ≤ 1.02 0 ≤ x ≤ 0.2 0.005 ≤ q ≤ 0.05 0.001 ≤ s ≤ 0.02