JP2680354B2 - Manufacturing method of multilayer ceramic electronic component - Google Patents

Description

The present invention relates to a method for manufacturing a monolithic ceramic electronic component, and in particular, a monolithic ceramic including a ceramic layer having a perovskite structure containing lead oxide. The present invention relates to a method of manufacturing an electronic component.

(Prior Art) With the development of ICs and LSIs, miniaturization and weight reduction, high reliability, high frequency, and cost reduction of electronic devices are rapidly spreading.
In order to meet these requirements, monolithic ceramic electronic components such as monolithic ceramic capacitors are widely used.

For example, a monolithic ceramic capacitor has a thickness of 15 to 100μ.
m ceramic dielectric layers and internal electrodes having a thickness of 2 to 3 μm are alternately stacked and integrally fired. The total capacitance (C) of this capacitor is expressed by the following equation.

C = ε _r ε _o (n−1) S / t, where ε _r is the relative permittivity of the ceramic dielectric layer, ε _o is the vacuum permittivity, n is the number of electrodes, and t is 1 of the dielectric layer. It is the thickness per layer.

As can be seen from this equation, in order to obtain a small-sized, large-capacity monolithic ceramic capacitor, it suffices to form a ceramic dielectric layer having a large ε _r and a small thickness.

By the way, as the material of this ceramic dielectric layer,
Exclusively, ceramic mainly composed of BaTiO ₃ have been used. However, with the increase in the number of laminated layers and the thinner dielectric layer, some problems have appeared in the ceramic capacitor using BaTiO ₃ . The most serious problem among them is the dependency of the dielectric constant on the bias voltage, that is, the large reduction in capacitance due to the DC voltage. For example, the dielectric constant is 10,00
When a rated voltage is applied to an F-characteristic multilayer ceramic capacitor having a thickness of 25 μm per layer, a rated voltage of 25 V, and a capacitance of 1 μF, the effective capacitance is only 0.3 μF, which is 70% down. Moreover, the temperature characteristics of the relative permittivity of the BaTiO ₃ -based multilayer capacitor with a permittivity of over 10,000 are large at -30 ℃ to + 85 ℃.
In the range of, the value will be 60-80% down. Furthermore, in this BaTiO ₃ -based multilayer capacitor, the capacity tends to decrease with time, and the capacity decreases by 20 to 25% in one year. In addition to these characteristic problems, BaTiO ₃ is usually
Since it is fired at a high temperature of 1350 ° C or higher, noble metals such as platinum, palladium and their alloys which do not react with the dielectric at this temperature must be used for the internal electrodes that are fired at the same time. The large capacity has a drawback that the cost becomes particularly high.

In order to improve the drawbacks of these BaTiO ₃ -based multilayer capacitors, Pb is used instead of Ba at the A site of the perovskite structure ABO ₃ and a composite perovskite compound (RELAXOR) is replaced by B at the B site, which has been widely studied. . Table 1 shows typical materials that have been studied so far for multilayer capacitors.

In this table, FE indicates a ferroelectric substance, AF indicates an antiferroelectric substance, and BaTiO ₃ does not include these complex perovskite compounds, but they are shown for comparison.

Since these materials can be fired at a low temperature of 800 to 1100 ° C, relatively inexpensive Ag / Pb alloy, Ni, Cu or the like can be used as the internal electrodes. Further, it has recently attracted particular attention because of its characteristics such that its temperature change is small despite its large permittivity, and it has excellent DC bias characteristics of permittivity. For example, those shown in US Pat. No. 3,472,777, US Pat. No. 4,078,938 and US Pat. No. 4,265,668 are known.

If integrally firing the laminate of the multilayer ceramic capacitor using the dielectric material, usually similar to the BaTiO ₃ based multilayer ceramic capacitor, Al ₂ O _3, MgO, ceramic having a ZrO ₂ or the like and each main component The laminated body before firing was placed on the setter or the lightweight setter made of these fibers, stacked, and the setter was placed in a sheath or the like, and the laminated body was fired in a closed or open state. .
This method is effective for firing a BaTiO ₃ -based multilayer ceramic capacitor, because an element having stable characteristics can be obtained and there is no variation in the characteristics of the fired element. However, when a monolithic ceramic capacitor containing lead oxide shown in Table 1 and having a perovskite structure is manufactured by using this method, its capacity is significantly reduced to 30% or more from a predetermined value, and further The capacity varied, and the yield decreased.

(Problems to be Solved by the Invention) A conventional method for manufacturing a monolithic ceramic electronic component including a ceramic dielectric layer having a perovskite structure containing lead oxide, for example, a method for manufacturing a monolithic ceramic capacitor, has a capacitance of a predetermined value. It was significantly reduced to 30% or more, and moreover, each capacitor caused variations in capacitance, resulting in reduced yield.

An object of the present invention is to provide a method of manufacturing a laminated ceramic electronic component including a ceramic layer having a perovskite structure containing lead oxide, such as a capacitor having stable characteristics such as no reduction in capacitance and no variation in capacitance. To do.

[Configuration of the invention]

(Means for Solving the Problems) According to the present invention, a ceramic body formed into a predetermined shape after adjusting raw materials and a plurality of internal electrodes are laminated so as to be stacked on each other to form a laminated body, and the laminated body is subjected to predetermined conditions. A laminated ceramic electronic component in which a sintered element including a ceramic layer having a perovskite structure containing lead oxide is fired by the method described above, and a pair of external electrodes electrically connected to the internal electrodes of the sintered element are provided in the sintered element. In the method of manufacturing a multilayer ceramic electronic component, the multilayer body is placed on a substrate having at least a surface having a perovskite structure containing lead oxide and fired. Further, in this method, the laminate is placed on a substrate having at least a surface having substantially the same composition as the ceramic layer and fired.

INDUSTRIAL APPLICABILITY The present invention is particularly effective for a method for producing a monolithic ceramic capacitor provided with a ceramic layer having a perovskite structure containing a large amount of lead oxide of 30 to 70 wt%, and in such a case, it was conventionally included in the ceramic layer. Since lead oxide is absorbed by the setter containing Al ₂ O ₃ or ZrO ₂ as a main component during firing, the content of lead oxide contained in the fired ceramic layer decreases to a predetermined amount or less, It has been found that the capacity decreases and the capacity fluctuates. It was also found that this absorption phenomenon appears remarkably when a setter containing Al ₂ O ₃ or ZrO ₂ as a main component is used. Moreover, lead oxide lost from the ceramic layer of the laminated body may be lost by evaporation during firing, but even if firing in a sealed state, the phenomenon of lead oxide disappearance occurs, and most of it is absorbed by the setter. You can understand when it is done.

In the production method of the present invention, since the laminate before firing is placed on the substrate having at least the above surface layer and fired, this surface layer acts as a barrier, and the ceramic layer The lead oxide contained in is not absorbed by the setter. Therefore, the content of lead oxide in the ceramic layer after firing does not decrease, and the decrease in capacity and the variation in capacity do not occur.

In the present invention, if at least the surface of the substrate on which the laminate is mounted has a perovskite structure containing preferably 30 to 70 wt% of lead oxide, it is baked on the surface of a ceramic substrate such as Al ₂ O _3. The formed film may be used, or the sintered powder may be spread on the surface of the substrate. Further, it is desirable that this surface layer has a thickness of 30 μm or more, and if the thickness is less than 30 μm, the action as a barrier cannot be expected. In the case of a film-shaped surface layer, if the thickness exceeds 200 μm, the surface layer may be peeled or cracked from a substrate made of a different material.
Further, this surface layer has substantially the same components as the ceramic layer of the laminate, from the viewpoint of impurities, in particular,
preferable.

The substrate on which the laminated body is placed may be a substrate made of ceramic having a perovskite structure containing lead oxide, preferably 30 to 70 wt%.

The ceramic layer of the multilayer ceramic electronic component according to the present invention is effective when it contains 30 to 70 wt% of lead oxide. If the content of lead oxide is out of this range, the dielectric constant of the ceramic layer becomes low, which is not preferable. Further, the firing temperature of the present invention is preferably in the range of 800 to 1300 ° C, and when the firing temperature is less than 800 ° C, the firing of the ceramic layer is insufficient and the predetermined characteristics cannot be obtained, and the firing temperature is 1300 ° C. If it exceeds, the ceramic layer reacts with the internal electrode during firing.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a state in which a laminated body for explaining an embodiment of the present invention is arranged in a setter, and FIG. 2 is a part showing a laminated ceramic capacitor manufactured according to the embodiment of the present invention. It is the perspective view which notched.

Example 1 First, as a composition of a ceramic layer, PbO, BaCO which is a raw material so that Pb _0.95 Ba _0.05 (Mg _1.3 Nb _2.3 ) _0.5 (Zn _1.3 Nb _2.3 ) _0.5 O ₃ (hereinafter referred to as A composition) is obtained.
Accurately weigh oxides and carbonates such as ₃ , Mg ₂ CO ₃ , Nb ₂ O ₅ , ZnO, and SrCO ₃ , calcinate them at a temperature of 800 to 860 ℃, and pulverize them with a ball mill to obtain a ceramic powder. Obtained. Disperse this ceramic powder in 35 wt% trichloroethane with a homogenizing mixer with a high speed rotating stirring blade, then add 5 wt% acrylic resin and 1-2 wt% phthalate ester and mix well to make a slurry. did. This slurry was poured onto a polyester film to prepare a 30 μm thick green sheet by the doctor blade method.

Next, the ceramic layer is peeled from the polyester film, punched to a predetermined size of 100 × 100 mm, after which an internal electrode made of Ag / Pd is screen-printed on one surface of the ceramic layer, and after drying, this The ceramic layers and the internal electrodes are laminated in a mold so that they are stacked alternately, and hot pressed at a pressure of 250 kg / cm ² at 80 ° C. for 10 minutes, and cut into a predetermined size to produce a laminated ceramic. A laminated body which is a raw chip of the capacitor was obtained.

As shown in Fig. 1, this laminate (1) is 100 x 50 x 2 mm.
Of Pb _0.95 Ba _0.05 (M
100 g _1.3 Nb _2.3 ) _0.5 (Zn _1.3 Nb _2.3 ) _0.5 O ₃ on a substrate (2) having a perovskite structure, and the substrates (2) are placed in a porcelain setter (3) made of Al ₂ O ₃ . Place it in 3
After degreasing at 50 ° C. for 10 hours, firing was performed at 1000 ° C. for 3 hours to obtain a sintered element. External electrodes commonly connected to internal electrodes were formed on this sintered element to obtain a monolithic ceramic capacitor. In this capacitor (4), as shown in FIG. 2, ceramic layers (5) containing lead oxide (PbO) and having a perovskite structure and internal electrodes (6) made of Ag / Pd were alternately laminated. It is composed of a sintered element (7) and a pair of external electrodes (8) for electrically connecting commonly a plurality of internal electrodes (6) of the sintered element (7). The capacitance value of this capacitor (4) was set to 50 V and 1 μF at the time of manufacture.

Example 2 As the composition of the ceramic layer, Pb _0.50 Sr _0.50 [(Zn _1.3 Nb
_2.3 ) _0.95 Ti _0.05 ] O ₃ (hereinafter referred to as B composition)
A laminated body formed in the same manner as in Example 1 has the same dimensions as in Example 1 and has Pb _0.50 Sr _0.50 [(Zn _1.3 Nb _2.3 ) _0.95 Ti _0.05 ].
It is arranged on a substrate having a composition of O ₃ and having a perovskite structure, and this substrate is placed in a porcelain setter made of Al ₂ O ₃ , and
After degreasing at 50 ° C. for 10 hours, firing was performed at 1100 ° C. for 3 hours to obtain a sintered element. External electrodes were formed on this sintered element to obtain a similar monolithic ceramic capacitor.

Example 3 As the composition of the ceramic layer, the laminated body formed in the same manner as in Example 1 so as to have the A composition was placed in an Al ₂ O ₃ setter having a surface layer having the A composition formed on the surface thereof. Line up,
A sintered element was manufactured in the same manner as in Example 1, and a similar monolithic ceramic capacitor was obtained.

Example 4 As the composition of the ceramic layer, the laminated body formed in the same manner as in Example 2 was arranged in a magnesia setter having a surface layer having the B composition formed on the surface thereof. A sintered element was manufactured in the same manner as in Example 2, and a similar monolithic ceramic capacitor was obtained.

Example 5 As the composition of the ceramic layer, the laminated body formed in the same manner as in Example 1 so as to have the A composition was arranged in a spinel setter having a surface layer having the A composition formed on the surface thereof. A sintered element was manufactured in the same manner as in Example 1, and further a similar monolithic ceramic capacitor was obtained.

Example 6 As a composition of a ceramic layer, a laminate formed in the same manner as in Example 2 so as to have a B composition was arranged in a zirconia setter having a surface layer having a B composition formed on the surface thereof. A sintered element was manufactured in the same manner as in Example 2, and a similar monolithic ceramic capacitor was obtained.

The characteristics such as capacitance of these laminated ceramic capacitors were measured, and the results are shown in Table 2. As a comparative example,
The laminated body was directly arranged in a setter made of Al ₂ O ₃ , magnesia, spinel, and zirconia to manufacture a laminated ceramic capacitor having a ceramic composition of A composition and B composition in the same manner as in Example 1 and Example 2. The measurement results of are shown in Table 2.

In this table, in the column of presence or absence of surface treatment, for example, “Yes, A composition” means that a slurry for forming a surface layer having A composition is applied to the surface of a setter, and this is applied to the firing temperature of the laminate. Means the one baked at the same temperature, and "none" means that the surface layer is not formed.

As is clear from this table, it is laminated on a substrate having a perovskite structure containing 30 to 70 wt% of lead oxide or on a porcelain setter made of Al ₂ O ₃ etc. coated with a surface layer having the same composition as this substrate. When the body is fired, it is possible to obtain a monolithic ceramic capacitor having a small dielectric loss and a small variation in capacitance and variation in withstand voltage.

As the composition of the ceramic layer of the monolithic ceramic capacitor and the surface layer formed on the substrate or the porcelain setter on which the laminated body is placed during firing, in addition to those described in the above examples, PbTiO ₃ , PbZrO ₃ , Pb (TiZr) O ₃ , Pb (Fe _1.2 Nb _1.2 )
O ₃ , Pb (Mg _1.3 Nb _2.3 ) O ₃ , Pb (Mg _1.2 W _1.2 ) O ₃ , Pb (Ni _1.3 Nb
_2.3 ) The present invention can be similarly applied to O ₃ .

Further, in the above embodiment, the case where the laminate is formed by the green sheet method has been described, but the present invention can be applied to the case where the laminate is formed by the printing lamination method.

Although the embodiments of the monolithic ceramic capacitor have been described above, other monolithic ceramics such as electrostrictive elements and piezoelectric elements for a monolithic actuator having a ceramic layer having a perovskite structure containing preferably 30 to 70 wt% of lead oxide. The present invention can be applied to electronic components.

〔The invention's effect〕

As described above, according to the present invention, there is provided a manufacturing method capable of obtaining a monolithic ceramic electronic component such as a monolithic ceramic capacitor having stable characteristics such as a reduction in capacitance and a variation in capacitance and a small dielectric loss. can do.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a laminated body for explaining an embodiment of the present invention is arranged in a setter, and FIG. 2 is a part showing a laminated ceramic capacitor manufactured according to the embodiment of the present invention. It is the perspective view which notched. 1 ... Laminated body 2 ... Substrate 3 ... Porcelain setter 4 ... Multilayer ceramic capacitor 5 ... Ceramic layer 6 ... Internal electrode 7 ... Sintered element 8 ... External electrode

Claims (2)

(57) [Claims] 1. A perovskite containing lead oxide is prepared by laminating a plurality of ceramic layers and internal electrodes formed in a predetermined shape after the raw material is adjusted so as to be alternately stacked, and firing the laminated body under predetermined conditions. In a method of manufacturing a laminated ceramic electronic component, which is a sintered element including a ceramic layer having a structure, and a pair of external electrodes electrically connected to internal electrodes of the sintered element are provided in the sintered element, A method for manufacturing a multilayer ceramic electronic component, comprising: placing on a substrate having at least a surface having a perovskite structure containing lead oxide and firing the substrate. 2. The method for producing a monolithic ceramic electronic component according to claim 1, wherein at least a surface of a substrate used for firing the laminate has substantially the same composition as that of the ceramic layer. .