JPH0650703B2 - 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 applied to the method. Examples of the ceramic laminated body include a multilayer ceramic wiring board and a laminated ceramic capacitor.

2. Description of the Related Art Conductive materials used for multilayer substrates include Au, Pt,
Noble metals such as Pd and base metals such as W, Mo and Cu are used. A paste is formed by adding an organic binder and a solvent to this metal material, which is screen-printed on an insulating substrate such as alumina and baked to form a conductor pattern. Further, in the case of a multi-layer substrate, in addition to these conductor pastes, a method of forming a multi-layer by using ceramic or glass powder as an insulating material dispersed in a solvent in which an organic binder is dissolved, and the insulating powder, the organic binder, etc. There is a method in which a pattern formed of the conductor paste is laminated on the green sheet 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, Mo, and Cu are base metals and are 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, in terms of reliability, Au has a problem of solder erosion, and Ag / Pd has a problem of high migration and conductor resistance. Therefore, Cu, which has low conductor resistance, low migration, and good solderability, has been attracting attention in recent years.

However, as described above, in order to use Cu, it is necessary to perform firing in a neutral atmosphere such as nitrogen, and
In a nitrogen atmosphere, 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 (sheet resistance, solder wettability, adhesive strength). On the contrary, when the oxygen concentration is high, the copper electrode is oxidized and the soldering performance is deteriorated. Therefore, firing is required to be performed while controlling a slight amount of oxygen in a nitrogen atmosphere. The same problem occurs in a laminated body using a green sheet such as a laminated ceramic capacitor.

That is, 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 blisters 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 Cu metallization are compatible with each other. In this method, copper oxide is used as the starting material for the electrode. According to this method, heat treatment for removing the binder is performed in air in advance, then copper oxide is reduced to metallic copper, and then firing is performed in nitrogen. It is a thing. This method is the most suitable method for obtaining a laminated body of Cu electrodes because binder removal is performed in advance, reduction and firing are performed. This multilayer method using copper oxide is disclosed in, for example, Japanese Patent Application No. 59-147833, and copper oxide paste is disclosed in Japanese Patent Application No.
No. 0-23846, Japanese Patent Application No. 62-121912, Japanese Patent Application No. 60-140816.

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 copper oxide paste during firing differs depending on the composition of the ceramic material. Therefore, the composition of the copper oxide paste must be selected according to the ceramic material to be laminated. However, the conventional copper oxide paste has problems such as cracking and delamination during firing, and electrode metallizing properties (adhesive strength, sheet resistance, etc.).

In view of the above problems, the present invention provides a copper oxide paste having good metallizing performance and good matching with a ceramic material for producing a ceramic laminate, 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 copper oxide paste of the present invention is such that the CuO powder is 80.0 to 99.0 wt% and the PbO powder is 0.5 to 1
0.0 _{wt%, MgO, Nb 2 O 5} , Ta 2 O 5, Ni
Manufacture of a ceramic laminate comprising an inorganic component containing 0.5 to 10% by weight of at least one selected from O, TiO ₂ , WO ₃ , CaO and ZnO, and an organic vehicle component composed of at least an organic binder and a solvent. The method includes 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 is composed of and.

Action The present invention is able to obtain good matching properties with a ceramic material by using the CuO paste having the above-mentioned configuration in producing a ceramic laminate and by the above-mentioned manufacturing method. CuO paste is P in addition to CuO
bO was added, and further MgO, Nb ₂ O ₅ , Ta
It is composed by adding an additive selected from ₂ O ₅ , NiO, TiO ₂ , WO ₃ , CaO and ZnO. The ceramic laminated body of the present invention is mainly applied to a ceramic multilayer wiring board, a laminated ceramic capacitor and the like.

In general, a glass-ceramic composite type is mainly used as a substrate material used for a ceramic multilayer wiring substrate because it needs to be sintered at a melting point of copper (1083 ° C.) or less.

This is a mixture of ceramic powder such as alumina and low softening point glass powder such as lead borosilicate glass. The glass has a function of low temperature firing and the alumina has a function of reinforcing strength. The reason for using lead borosilicate glass powder is that it has a low softening point glass among glass materials, and that it has excellent insulating properties,
Also, since the thermal expansion coefficient is close to that of Si, it is suitable for bare chip mounting on a substrate.

A lead composite perovskite material for using copper as an electrode is used as the dielectric material of the monolithic ceramic capacitor. This is inevitably determined from the necessity of sintering below the melting point of copper, as described above. The CuO paste of the present invention can improve wettability and reactivity with a substrate material by simultaneously adding PbO and other additives to the ceramic laminate composition as described above. Suitable for integration with objects.

In addition, the outline of the method for producing a laminate is to form a green laminate of the CuO paste of the present invention and a ceramic material (mainly the green sheet of the ceramic composition and the printing of the CuO paste are laminated), and the laminate is prepared in the air. The binder is removed by heat treatment. This is the reason why CuO is used as the starting material of the conductor. That is, in this step, only the organic binder in the laminate is removed, and CuO and other additives inside do not undergo any reaction or sintering. Then, at low temperature, only CuO is reduced without reducing the ceramic material (preferably 15).
Hydrogen atmosphere at 0 to 300 ° C). Further, the ceramic material and the conductor material are sintered by firing in a nitrogen atmosphere (desirably about 900 to 950 ° C.).

The CuO powder of the conductor layer does not undergo a large sintering reaction during binder removal, but on the other hand, it becomes Cu metal during reduction and undergoes significant volume shrinkage. Therefore, with a conductor composition containing only CuO powder, the contraction of Cu is too large, which may cause a gap between the electrode and the ceramic layer or a crack in the ceramic layer. However, the CuO composition of the present invention does not cause the above problems. That is, the additive PbO reacts with the ceramic material near the melting point (880 ° C.), and by adding another additive 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.

When PbO is added alone, the reaction with the ceramic material is good, but the shrinkage of the electrode layer is too large, so delamination is likely to occur. Further, the other additives alone serve only as a filler, failing to obtain adhesiveness with the ceramic, and cause cracks to occur.

Further, if the total amount of the additive is 0.1% by weight or less with respect to the amount of CuO powder, good metallization cannot be obtained, and conversely, if it is 20% by weight or more, the shrinkage of the conductor layer is too small and matching with the sintered body is achieved. The sex becomes worse. Desirably, PbO is 1 to 3
%, And 1 to 5% by weight of other additives are good.

Example 1 A multilayer ceramic capacitor of one 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 an internal electrode layer, 2 is a ceramic dielectric material, and 3 is an external electrode.

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.

First, the dielectric material according to the present invention is based on Pb (Mg _1/3 Nb _2/3 ) O ₃ and also contains PbTiO ₃ ,
The one to which Pb (Ni _1/2 W _1/2 ) O ₃ was added was used. The average particle size is 1.5 μm, and Mg columbite is prepared in advance as a dielectric (MgO, Nb ₂ O ₅ is calcined at 1000 ° C.), and then other components are added thereto and calcined again (about 800).
℃) and crushed. This dielectric was used as an inorganic component, polyvinyl butyral as an organic binder, DBP as a plasticizer, and a mixed solution 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 copper oxide paste will be described.

As the copper oxide powder, one having an average particle size of 2.5 μm was used, and other reagents such as PbO, MgO, Nb ₂ O ₅ , Ta ₂ O ₅ , NiO,
TiO ₂ , WO ₃ , CaO, and ZnO were made to have 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.

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

The CuO paste (NO. 4) 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 2.88mm
² (1.2 × 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 CuO 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 cupric oxide is diffused into the dielectric much 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. The results of the binder removal temperature and the dielectric characteristics are
Shown in the table.

The holding time at each temperature was 2 hours, and the temperature rising / falling speed was 100 (° C./hour). The evaluation was conducted through the subsequent steps of reduction and firing, and the commercially available C was used as an external electrode.
It is the result after applying u paste on the end face and baking in nitrogen at 900 ° C. for 10 minutes.

The optimum binder removal temperature is in the range of 300 ° C to 800 ° C. Below 300 ° C, carbon remains due to undecomposition of the organic binder and lead oxide in the dielectric material is reduced, and the dielectric property cannot be obtained. It is believed that Conversely, 800
It is considered that at temperatures above ℃, the electrode cannot be reduced in the reduction step after sintering of the dielectric.

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. The results are shown in Table 4.

At this time, the binder removal temperature is 700 ° C., and the firing is 900
It was performed at ° C. As a result of performance evaluation, it can be seen that the reduction to metallic copper sufficiently occurs at 150 ° C. or higher. It is considered that below that, since the copper oxide remained as it was, it did not function as an electrode and the dielectric characteristics were not obtained. On the contrary, at 350 ° C. or higher, the lead oxide component in the dielectric is reduced and the dielectric turns gray. If metallic lead is present in the dielectric, the dielectric characteristics cannot be obtained, and upon firing, it also reacts with metallic copper to precipitate a low melting point Cu—Pb alloy. Therefore, the reduction temperature is preferably 150 to 300 ° C. Next, the firing process will be described.

The firing was performed in a belt type electric furnace in a nitrogen atmosphere. The internal residual oxygen amount was 1 to 2 ppm, and the temperature range was 800 ° C to 1100 ° C. The Cu paste for external electrodes was applied to the terminal portion of the multilayer capacitor manufactured as described above and baked in the same baking furnace as described above.

Table 5 shows the evaluation results of the firing temperature and the dielectric properties.

Regarding the effect of the firing temperature, good dielectric properties are obtained in the range of 850 to 1050 ° C.

Table 6 shows the evaluation results of the CuO paste under the standard conditions.

From Table 6, delamination is likely to occur when PbO alone is used as an additive, and effective dielectric properties and matching are obtained when PbO is added at the same time as other additives. Also,
When the other additives were added alone, delamination occurred.

Example 2 Next, an example of compounding a ceramic substrate and the dielectric will be described. The ceramic substrate material is composed of glass and alumina powder having the composition shown in Table 7.

The substrate material having the composition shown in Table 7 has a sintering temperature of about 900 ° C.
Is. An organic binder, a solvent and a plasticizer are added to this material as in Example 1 to produce a green sheet.

The green sheet made of substrate material has a thickness of about 200 μm.
The holes for the through holes are punched.

Next, the CuO paste used in Example 1 was used in the same manner.

The multi-layer substrate is manufactured by forming the Cu on the green sheet.
The conductor pattern is screen-printed with O paste (NO.4). Similarly, an electrode pattern is screen-printed on the dielectric green sheet produced in Example 1 with CuO paste (NO.4), and the desired number of the above-mentioned substrate green sheet and dielectric green sheet are laminated and heated. Crimped.
At this time, the dielectric green sheet was formed inside the substrate green sheet. Next, the stacked unsintered substrates are manufactured through the steps of removing the binder, reducing and firing.

The conditions of each process were the standard conditions of Example 1 (binder removal, reduction, and firing were 600 ° C., 200 ° C., 900 ° C.).

On the surface of the multi-layer substrate thus produced, commercially available C
Print the top layer pattern using u paste, 900 ℃
Was fired in a nitrogen atmosphere. Further, a glaze resistor was printed on the surface of this substrate and baked. In order to evaluate the characteristics of the glaze resistor, one formed on an alumina substrate was also prepared and evaluated for comparison. The results are shown in Table 8.

The glaze resistor used is a mixture of barium borosilicate glass and titanium silicide powder mixed with a vehicle and kneaded. Four types of sheets having sheet resistances of 10, 100, 1K and 10KΩ / □ were used depending on the amounts of glass and silicide. As can be seen from Table 8, the same performance as on the alumina substrate was obtained and there was no problem in actual use.

Also, the dielectric properties formed inside are converted to a dielectric constant of about 5
000 or more, and the dielectric loss was about 0.5% or less.

In this embodiment, the glaze resistor was fired after the substrate was fired, but similar results were obtained by forming it in the substrate and firing it simultaneously. This means that a dielectric and a resistor can be formed in the substrate material, which is an effective means for obtaining a high-density wiring substrate in the future.

As described above, according to the present invention, the CuO powder is 80.0 to 99.0% by weight,
0.5 to 10.0% by weight of PbO powder, MgO, Nb ₂ O ₅ ,
Ta ₂ O ₅ , NiO, TiO ₂ , WO ₃ , CaO, Zn
0.5-10.0% by weight of at least one selected from O
By using the contained paste composition, it is possible to obtain a good laminate that is highly compatible 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,
This is composed of a firing process in nitrogen, which makes it possible to easily control the atmosphere and achieve highly reliable Cu metallization.

[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 (16)

[Claims] 1. CuO powder 80.0-99.0% by weight, PbO powder
0.5 to 10.0% by weight of MgO, Nb ₂ O ₅ , Ta
_{2 O 5, NiO, TiO 2} , WO 3, CaO, and an inorganic component at least one or more containing 0.5 to 10 wt% selected from ZnO, further comprising an organic vehicle component consisting of at least an organic binder and a solvent A characteristic paste composition. 2. A method of manufacturing a multilayer ceramic capacitor using a lead composite perovskite compound as a dielectric, wherein an internal electrode paste composition comprises CuO powder 80.0-99.0% by weight,
0.5 to 10.0% by weight of PbO powder, MgO, Nb ₂ O ₅ ,
Ta ₂ O ₅ , NiO, TiO ₂ , WO ₃ , CaO, Zn
0.5 to 10% by weight of at least one selected from O
An inorganic component contained, and consisting of at least an organic vehicle component consisting of an organic binder and a solvent, a step of removing the organic binder by heat treatment in air, a step of reducing the internal electrode by heat treatment in hydrogen, A method of manufacturing a monolithic ceramic capacitor, which comprises a step of sintering a dielectric and an internal electrode by heat treatment in nitrogen. 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 850 to 1050 ° C. 6. A dielectric composition comprising Pb (Mg _1/3 Nb _2/3 ) O ₃ ,
The method for producing a multilayer ceramic capacitor according to claim (2), characterized in that a mixture of PbTiO ₃ and Pb (Ni _1/2 W _1/2 ) O ₃ is contained as a main component. 7. A method for producing a ceramic multilayer wiring board using a glass-ceramic mixture as an insulating material, wherein the conductor wiring paste composition comprises CuO powder 80.0-99.0% by weight and Pb.
0.5 to 10.0 wt% of O powder, MgO, Nb ₂ O ₅ , Ta
₂ O ₅ , NiO, TiO ₂ , WO ₃ , CaO, ZnO, an inorganic vehicle component containing 0.5 to 10 wt% of at least one selected from the following, an organic vehicle component composed of at least an organic binder and a solvent, and air. A heat treatment in a heat treatment to remove the organic binder, a heat treatment in hydrogen to reduce the inner electrode, and a heat treatment in nitrogen to sinter the dielectric and the inner electrode. A method for manufacturing a multilayer ceramic wiring board, comprising: 8. The method for producing a multilayer ceramic wiring board according to claim 7, wherein the organic binder is removed in a temperature range of 300 to 800 ° C. 9. The method for producing a multilayer ceramic wiring board according to claim 7, wherein the reduction heat treatment is performed in a temperature range of 150 to 300 ° C. 10. The method for producing a multilayer ceramic wiring board according to claim 7, wherein the firing temperature is in the temperature range of 850 to 950 ° C. 11. A method for forming a capacitor and / or a resistor having a lead composite perovskite compound as a dielectric inside a ceramic multilayer wiring board having a glass-ceramic mixture as an insulating material, comprising a conductor wiring paste composition. CuO powder 80.0-99.0% by weight, PbO powder 0.5
To 10.0 wt% MgO, Nb ₂ O ₅ , Ta ₂ O ₅ , N
Heat treatment in air comprising an inorganic component containing 0.5 to 10% by weight of at least one selected from iO, TiO ₂ , WO ₃ , CaO and ZnO, and an organic vehicle component composed of at least an organic binder and a solvent. Is used to remove the organic binder, a heat treatment in hydrogen is performed to reduce the internal electrodes, and a heat treatment in nitrogen is performed to sinter the dielectric and the internal electrodes. Manufacturing method of multilayer ceramic wiring board. 12. Removal of the organic binder from 300 to 800 ° C.
The method for manufacturing a multilayer ceramic wiring board according to claim 11, wherein the method is performed in the temperature range of. 13. The method for producing a multilayer ceramic wiring board according to claim 11, wherein the reduction heat treatment is performed in a temperature range of 150 to 300 ° C. 14. The method for producing a multilayer ceramic wiring board according to claim 11, wherein the firing temperature is in the temperature range of 850 to 950 ° C. 15. The resistor material comprises a paste containing a silicide and a glass mixture as main components.
1) A method for manufacturing a multilayer ceramic wiring board as described above. 16. The dielectric composition comprises Pb (Mg _1/3 Nb _2/3 ).
12. The method for producing a multilayer ceramic wiring board according to claim 11, wherein the main component is a mixture of O ₃ , PbTiO ₃ , and Pb (Ni _1/2 W _1/2 ) O ₃ .