JPH07183155A - Laminated ceramic electronic component and its manufacture - Google Patents

Abstract

PURPOSE:To provide highly reliable a laminated ceramic electronic component which is hardly deteriorated in mechanism strength and insulation resistance even when a Pb-bearing composite perovskite-type ceramic is used. CONSTITUTION:A laminated capacitor 1 in which a plurality of internal electrodes 3-7 are arranged in such a way that the electrodes 3-7 are overlapped upon another with ceramic layers in between in a sintered body 2 composed of a Pb-bearing composite perovskitetype ceramic and the electrodes 3-7 are constituted of porous layers of 70-90% in porosity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic laminated electronic component formed by using Pb-based composite perovskite type ceramics and a method for manufacturing the same, and more particularly, to a ceramic laminated electronic component having improved internal electrodes arranged in the ceramic. The present invention relates to a component and a manufacturing method thereof.

[0002]

2. Description of the Related Art In multilayer capacitors, multilayer substrates, multilayer piezoelectric components, etc., a ceramic material that can be sintered at a lower temperature is required in order to use an inexpensive metal material as an internal electrode. . In order to meet such requirements, Pb-based composite perovskite-type ceramics have been proposed. The Pb-based composite perovskite-type ceramics not only can be fired at a low temperature, but also exhibit excellent electrical characteristics.

Pb-based composite perovskite-type dielectric ceramics have the general formula

[0004]

[Chemical 1]

It has a composition represented by: In the general formula (1), α is Ca, Sr, Ba, Ag, L
a represents at least one atom of Nd, x is 0 or more and 0.5 or less, β is Mg, Zn, Ni, Cu, Fe,
One or more atoms of Mn and In, γ is Nb,
At least one atom selected from W, Ta, and Sb is shown.

To obtain the Pb-based composite perovskite-type dielectric ceramic, oxide powders of respective atoms are weighed and mixed so as to realize the composition of the general formula (1). Then, the mixed powder is dried, calcined, and the calcined product is crushed to obtain a raw material powder. Further, after the obtained raw material powder is dried, a resin binder is added and molded, and the obtained molded body is fired.

[0007]

However, the above-mentioned P
Since the b-type composite perovskite ceramics contain lead in the composition, lead scatters during firing. Therefore, in order to compensate for the reduction of lead due to scattering, prepare a raw material powder containing lead in excess with respect to the composition represented by the general formula in advance,
Sintered bodies are often manufactured.

However, in a multilayer capacitor, for example, a plurality of internal electrodes are arranged in the sintered body so as to overlap with each other via the ceramic layer. Therefore, when obtaining the above-mentioned sintered body, a ceramic laminated body in which the internal electrode materials are laminated via the unfired ceramic layer is prepared, and the laminated body is fired.

By the way, during the firing, Pb scatters as described above, but since the internal electrodes are laminated via the ceramic layer, the scattering of Pb is suppressed by the internal electrodes. That is, the internal electrodes serve as walls to prevent the scattering of Pb. Therefore, the concentration of Pb is low near the outer surface of the obtained sintered body, Pb remains in a relatively high concentration in the ceramic layer between the internal electrodes, and the excessively added Pb is not uniform in the sintered body. Tended to exist in. As a result, the mechanical strength is reduced in a portion where Pb is excessively remained, and the obtained multilayer capacitor is defective in insulation resistance and acquired capacitance, and thus it is possible to obtain a highly reliable multilayer capacitor. could not.

An object of the present invention is a ceramic laminated electronic component using a Pb-based composite perovskite type ceramics, in which excess Pb is not likely to remain, insulation resistance failure and mechanical strength reduction are unlikely to occur, and reliability is improved. An object of the present invention is to provide an excellent ceramic laminated electronic component and a manufacturing method thereof.

[0011]

The invention according to claim 1 has a structure in which a plurality of internal electrodes are arranged so as to overlap with each other through a ceramic layer in a sintered body made of a Pb-based composite perovskite type ceramics. In the laminated ceramic electronic component, the internal electrode has a porosity of 70 to
Characterized by being composed of 90% porous layer,
It is a ceramic laminated electronic component.

The invention described in claim 2 is the method for manufacturing a laminated ceramic electronic component according to the invention described in claim 1, wherein a plurality of conductive pastes containing metal powder, ceramic powder and resin binder are used. And a step of preparing a laminated body in which the internal electrodes are laminated so as to be overlapped with each other via a ceramic green sheet, and a step of firing the laminated body to fire the ceramics and the internal electrodes.

As described above, the present invention provides a ceramic laminated electronic component using the Pb-based composite perovskite-type ceramics and a method for manufacturing the same. The Pb-based composite perovskite-type dielectric ceramics are mentioned above. It has a composition represented by the general formula (1), and specific examples of such a composition include Pb (Fe _1/3 Nb _2/3 ) O ₃ and Pb (Fe
_{2/3 W 1/3) O 3, Pb} (Ni 1/3 Nb 2/3, Pb (M
g _1/2 W _1/2 ) O ₃ , Pb (Mn _1/3 Nb _2/3 ) O ₃ ,
Pb (Mg _1/3 Ta _2/3 ) O ₃ , Pb (Co _1/3 Nb
_2/3 ) O ₃ , Pb (Co _1/2 W _1/2 ) O _{3 and the} like. Among these compositions, part of Pb is Ba or C.
Also included are compositions substituted with one or more metals such as a, Sr, La, Nd or Ag.

In addition, the composition of the Pb-based composite perovskite ceramics contains MnO 2 in order to improve the dielectric properties.
Various additives such as ₂ , MgO, NiO, ZrO ₂ , CoO, Sb ₂ O ₃ or La ₂ O may be added.

The composition of the Pb-based composite perovskite ceramics is merely an example, and dielectric ceramics and piezoelectric ceramics for forming piezoelectric elements may be used.

According to the first and second aspects of the present invention, a ceramic laminated electron having a structure in which a plurality of internal electrodes are arranged so as to overlap each other through a ceramic layer in a sintered body made of the Pb-based composite perovskite type ceramics. The invention according to claim 1 relates to a component and a method for manufacturing the component, and the internal electrode has a porosity of 70 to 90 as described above.
% Of the porous layer, the invention according to claim 2 is characterized in that the internal electrode comprises a plurality of internal electrode materials made of a conductive paste containing a metal powder, a ceramic powder and a resin binder as a starting material. It is characterized by being used as.

If the porosity is less than 70%, a defective joint between the internal electrode and the external electrode may occur, or desired electrical characteristics such as capacitance cannot be obtained. On the other hand,
When the porosity exceeds 90%, similarly to the conventional example, the internal electrodes serve as walls to suppress the scattering of Pb, and Pb remains unevenly. Therefore, the porosity needs to be in the range of 70 to 90%.

In the second aspect of the invention, the metal powder contained in the conductive paste is an appropriate metal powder conventionally used to form a conductive paste for internal electrodes, such as Ag or Ag-. Pd, Ni or Cu
A metal powder such as can be used.

The ceramic powder is added to form pores in the internal electrode with a porosity of 70 to 90% during firing. As the ceramic powder, the specific porosity described above is used. As long as the range can be realized, a material having an appropriate material and particle size can be used. However, preferably, in order to enhance the adhesion between the ceramic powder and the ceramic layers located above and below the internal electrode, and to bring the firing temperatures of the ceramics constituting the ceramic powder and the upper and lower ceramic layers close to each other, As the ceramic powder, it is desirable to use Pb-based composite perovskite-type ceramics that form the upper and lower ceramic layers.

As the resin binder contained in the above-mentioned conductive paste, an appropriate resin binder conventionally used to form an internal electrode, such as polyvinyl butyral, can be used.

According to the second aspect of the present invention, the internal electrode layer is formed by using the conductive paste, and the ceramic powder is contained in the conductive paste during firing. Are formed on the internal electrode layers. The ratio of these holes to the internal electrode plane area,
That is, a predetermined amount of ceramic powder is added to the conductive paste so that the porosity is 70 to 90%. However, the addition ratio of the ceramic powder differs depending on the type and particle size of the metal powder used, the type and particle size of the ceramic powder, the type and addition ratio of the resin binder, and so cannot be uniquely determined.

[0022]

In the invention described in claim 1, since the internal electrode is composed of the porous layer having the porosity of 70 to 90%, the ceramic layer made of the Pb-based composite perovskite type ceramics is used during firing. Excess Pb in the inside can be scattered without being hindered by the internal electrodes. That is, since the internal electrode serves as a wall in the past to prevent the excessive addition of Pb from scattering, there is a problem that the excessive addition of Pb finally exists unevenly in the sintered body. On the other hand, in the invention described in claim 1, since Pb can be scattered from the pores, the Pb concentration in the sintered body can be kept uniform.

According to the second aspect of the present invention, the conductive paste for forming the internal electrodes contains ceramic powder, and the ceramic powder forms pores, whereby the specific porosity is increased. A range of internal electrode layers are formed. Therefore, as in the case of the invention described in claim 1, since Pb is smoothly scattered, it is possible to reduce the variation in the concentration of Pb in the finally obtained sintered body.

Therefore, according to the first and second aspects of the present invention, it is possible to provide a highly reliable ceramic laminated electronic component which is unlikely to cause a partial decrease in mechanical strength or a defective insulation resistance. Becomes

The present invention is not limited to the multilayer capacitor, and is applied to various ceramic multilayer electronic components including a multilayer piezoelectric resonance component and a ceramic multilayer substrate having a structure in which internal electrodes are overlapped with each other with a ceramic layer interposed therebetween. be able to.

[0026]

Description of Examples Example 1 As raw materials for a Pb-based composite perovskite ceramic containing lead oxide, Pb (Mg _1/3 Nb _2/3 ) O ₃ and PbTi were used.
A powder obtained by mixing O ₃ in a molar ratio of 0.96 to 0.04 was used.

Polyvinyl butyral resin binder and ethanol as a solvent were added to the above raw material powder, and wet-mixed in a ball mill for 16 hours. The obtained mixture was formed into a sheet by a doctor blade method, dried, and cut into a rectangular shape to obtain a ceramic green sheet having a rectangular planar shape.

A conductive paste containing silver-palladium alloy powder and a resin binder is printed on one side of the obtained ceramic green sheet, and a plurality of ceramic green sheets having the internal electrodes made of the conductive paste are laminated to form a thick layer. A laminated body was obtained by pressing in the direction. The obtained laminated body was fired in air at a temperature of 800 to 1000 ° C. for 3 hours to obtain a sintered body. An Ag paste to be an external electrode was applied to both end faces of the obtained sintered body and baked at 700 ° C. to form an external electrode. Thus, the multilayer capacitor 1 shown in FIGS. 1 and 2 was produced. 1 and 2,
The monolithic capacitor 1 has a sintered body 2 in which internal electrodes 3 to 7 are laminated via ceramic layers. In addition, 8, 9
Indicates an external electrode. The manufactured multilayer capacitor 1 has a width =
It has a size of 1.6 mm, length = 3.2 mm, and thickness = 1.5 mm.

In order to obtain the above-mentioned laminated capacitor, the silver in the conductive paste containing silver-palladium alloy powder-
By changing the content of the palladium alloy powder variously, as shown in Table 1 below, multilayer capacitors of sample numbers 1 to 7 having internal electrodes with various porosities were obtained.

The capacitance and insulation resistance of each of the obtained multilayer capacitors were measured. In addition, as a humidity resistance load test, the following Table 1 was used in an atmosphere of 70 ° C. and 95% relative humidity.
After standing for the time shown in (3), a voltage of 32 V was applied between the external electrodes, and the rate of insulation failure was determined.

[0031]

[Table 1]

As is clear from Table 1, the porosity is 70%.
It can be seen that the sample numbers 1 and 2 having the internal electrodes of less than 1 cannot obtain a sufficiently large capacitance. Further, in the laminated capacitor of sample number 7 having a porosity of more than 90%,
It can be seen that the insulation resistance is low and that insulation failure products tend to occur in the moisture resistance load test. On the other hand, in the multilayer capacitors of Sample Nos. 2 to 6 having internal electrodes having a porosity of 70% to 90%, a sufficiently large capacitance can be obtained, and insulation resistance failure and humidity resistance load test are performed. It can be seen that the defect is unlikely to occur.

Example 2 In the same manner as in Example 1, a laminated capacitor of the same sample as in Example 1 was produced.

First, using the same Pb-based composite perovskite powder raw material as in Example 1, a ceramic green sheet was produced in the same manner as in Example 1. Next, a conductive paste described below was printed on one surface of the obtained ceramic green sheet, and a laminated capacitor was produced in the same manner as in Example 1.

The conductive paste used in Example 2 contained silver-palladium alloy powder, resin binder and ceramic powder. The same ceramic powder as the Pb-based composite perovskite type raw material powder was used, provided that As shown in Table 2 below, plural kinds of conductive pastes having different ceramic powder contents were prepared. Using these plural kinds of conductive pastes, laminated capacitors were manufactured according to the above method. The obtained multilayer capacitor was evaluated in the same manner as in Example 1.
The results are shown in Table 2 below.

In addition, the porosity of the internal electrodes formed by using the various conductive pastes prepared as described above is calculated by screen-printing and baking the conductive pastes on the glass substrate. It was determined by optically measuring the porosity. The porosity of the internal electrode thus obtained is also shown in Table 2.

[0037]

[Table 2]

As is clear from Table 2, in the sample No. 11 containing no ceramic powder in the conductive paste,
Insulation resistance is low, probably because Pb is unevenly distributed.
In the moisture resistance load test, defective products were likely to occur to some extent. Further, it can be seen that the capacitance of the multilayer capacitor (Sample No. 16) using the conductive paste with the ceramic powder mixing ratio of 35% by volume is as low as 0.87 μF.

On the other hand, the mixing ratio of the ceramic powder is 5% by volume to 30% by volume, so that the porosity is 70-9.
It can be seen that the multilayer capacitors of Sample Nos. 12 to 15 in which the range is 0% can obtain a sufficiently large electrostatic capacity and do not cause insulation resistance failure or failure in the moisture resistance load test.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a multilayer capacitor manufactured in Example 1.

FIG. 2 is a plan sectional view of the multilayer capacitor shown in FIG.

[Explanation of symbols]

 1 ... Multilayer capacitor 2 ... Sintered body 3-7 ... Internal electrodes

Claims (2)

[Claims] 1. A ceramic laminated electronic component having a structure in which a plurality of internal electrodes are arranged to overlap each other with a ceramic layer in a sintered body made of Pb-based composite perovskite ceramics, wherein the internal electrodes are empty. A ceramic laminated electronic component comprising a porous layer having a porosity of 70 to 90%. 2. A step of preparing a laminated body in which a plurality of internal electrodes made of a conductive paste containing a metal powder, a ceramic powder and a resin binder are laminated so as to overlap with each other via a ceramic green sheet, and the laminated body is fired. The method for producing a ceramic laminated electronic component according to claim 1, further comprising the step of firing the ceramics and the internal electrodes.