JPH0574648A - Laminated electronic component - Google Patents

Abstract

PURPOSE:To obtain a laminated electronic component in which a decrease in an insulating resistance can be suppressed inexpensively even under a conventional baking condition by composing at least part of ceramic sintered unit of nonreducing ceramic material and employing an antioxidative copper alloy, in which one or more types of Si, Al, Be, Mg and Zn are added, as inner electrodes. CONSTITUTION:A laminated electronic component is formed of a ceramic sintered unit 2 obtained by integrally baking a plurality of ceramic green sheets to be laminated through at least one inner electrode 1 together with the electrode l. In such a laminated electronic component, at least part of the unit 2 is formed of a nonreducing ceramic material, and as the electrode 1, an antioxidative copper alloy, in which at least one type of 0.01-2.5wt.% of Si, 10.01-16.0wt.% of Al, 0.01-4.0wt.% of Be, 0.01-0.8wt.% of Mg and 1.0-59.5wt.% of Zn is added, is used. The component is, for example, a laminated ceramic capacitor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated electronic component, and more particularly to a laminated electronic component such as a laminated ceramic capacitor in which internal electrodes and ceramic green sheets are superposed and integrally fired.

[0002]

2. Description of the Related Art Normally, a laminated ceramic capacitor is formed by laminating a predetermined number of dielectric ceramics and internal electrodes on each other.
It has a structure in which a pair of external electrodes is provided at both ends. An electrostatic capacitance is generated between the internal electrodes facing each other in the vertical direction, and this electrostatic capacitance is taken out from the external electrodes.

Conventionally, in the manufacturing process of such a monolithic ceramic capacitor, Pd and P are used as internal electrode materials.
Noble metals such as t and Ag-Pd were used. However, these noble metals are expensive and have been a major factor in preventing cost reduction of the monolithic ceramic capacitor. Therefore, in recent years, an inexpensive base metal has been used as a material for the internal electrodes. For example, when copper is used as the internal electrode material, copper is significantly oxidized in a natural atmosphere at 150 ° C. or higher, and its melting point is as low as 1083 ° C.
It is fired in a neutral atmosphere at 1080 ° C or lower. As a dielectric ceramic which is used under such conditions and whose characteristics do not deteriorate, a Pb-based material is disclosed in JP-A-62-8745.
5 gazette, the same 63-17252 gazette, the same 63-172.
No. 51 and No. 63-319241.

[0004]

The material disclosed in the above publication is a dielectric ceramic containing lead oxide, and when a laminated body made of these and a metal copper paste to be an internal electrode is fired, the dielectric is reduced. And the internal electrodes must be fired in a neutral atmosphere that does not oxidize. Insulation resistance decreases when the dielectric is reduced, and equivalent series resistance increases when the internal electrode is oxidized, or copper oxide diffuses into the dielectric. Lose.

Regarding the relationship between the oxygen partial pressures of lead and copper and the temperature, see L. S. Darkeh,
R W Gurry, Raga Physical Chemistry of Metals (Phy)
(sical Chemistry of Metals)
(1953), as shown in Figure 3, 4C
Copper is not oxidized in a region below the line of the reaction formula of u + O ₂ = 2Cu ₂ O, and lead oxide is not reduced in a region above the line of the reaction formula of 2Pb + O ₂ = 2PbO. Therefore, theoretically, it is best if the laminate is fired in a region sandwiched between these two lines, but that region is very narrow (for example, at 1000 ° C., the oxygen partial pressure is about 5 × 1).
It is 0 ⁻⁷ to about 8 × 10 ⁻⁸ atm), and it is very difficult in production technology to actually control the oxygen partial pressure within such a range.

Therefore, in the production stage, defects such as increase in equivalent series resistance due to oxidation of internal electrodes, diffusion into the dielectric, and reduction in insulation resistance due to reduction of the dielectric ceramic are likely to occur. Was there. When the binder is burned out in a low oxygen partial pressure atmosphere in which the internal electrodes are not oxidized as much as possible, carbonization of the binder component is likely to occur. For this reason, there is a problem in that the dielectric is reduced by the remaining carbon during firing, resulting in a decrease in the insulation resistance of the element and a decrease in the sintering density.

An object of the present invention is to eliminate the above-mentioned problems, and at low cost and under conventional firing conditions,
Provided is a multilayer electronic component capable of suppressing the occurrence of defects such as a decrease in insulation resistance.

[0008]

In order to solve the above problems, a laminated electronic component according to the present invention comprises a ceramic sintered body obtained by integrally firing an internal electrode and a ceramic green sheet. At least a part of the ceramic sintered body is composed of a non-reducing ceramic material, and as an internal electrode, Si: 0.01 to 2.5 w
t%, Al: 0.01 to 16.0 wt%, Be: 0.0
1 to 4.0 wt%, Mg: 0.01 to 0.8 wt% or Zn: 1.0 to 59.5 wt% using an oxidation resistant copper alloy containing at least one kind as an additive element. To do.

[0009]

[Function] When the copper alloy having excellent resistance to oxidation at high temperature is used as an internal electrode material, the range of calcinable atmosphere expands to the oxidation side, which not only facilitates control of oxygen partial pressure but also suppresses oxidation. By doing so, unnecessary diffusion of the internal electrode constituent metal into the unit can be reduced. Further, since it becomes possible to perform firing on the side of higher oxygen partial pressure, it is possible to prevent characteristic deterioration such as reduction of insulation resistance or reduction of dielectric constant due to reduction of the ceramic layer.

Further, when the copper alloy is used as a material for the internal electrodes, the adhesion strength between the ceramic layer and the internal electrodes is improved, so that delamination in the laminated electronic component can be suppressed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a laminated electronic component according to the present invention will be described below in detail with reference to the drawings. The embodiment described below is an application of the present invention to a monolithic ceramic capacitor. In FIG. 1, a monolithic ceramic capacitor comprises a plurality of dielectric ceramics 2 and a plurality of internal electrodes 1 for forming capacitances which are arranged in a laminated state with the dielectric ceramics 2 interposed therebetween. , A pair of external electrodes 3 for extracting capacitance, which are connected to predetermined ones of the internal electrodes 1. As the dielectric ceramic 2, a dielectric material having excellent reduction resistance is used. As the internal electrode 1, a cheap base metal, a copper alloy having high electric conductivity and strong oxidation resistance at high temperature is used. Examples of the material of the external electrode 3 include nickel or copper, alloys thereof, copper added with glass frit, copper alloy, silver, palladium, silver-palladium alloy, or the like. Any material can be used.

Here, specific examples of each material and the manufacturing process of the capacitor will be described in detail. Specifically, a three-component composition of 92Pb (Mg _1/3 Nb _2/3 ) O ₃ −2Pb (Cu _1/2 W _1/2 ) −6PbTiO ₃ (mol%) was obtained as the dielectric powder. To PbO, MgC
O ₃ , Nb ₂ O ₅ , TiO ₃ , CuO and WO ₃ were weighed, wet mixed in a ball mill for 16 hours and then evaporated to dryness to obtain a mixed powder. The powder thus obtained was placed in a zirconia-shaped box, baked at 680 to 730 ° C. for 2 hours, and then coarsely pulverized so as to pass through a 200-mesh sieve to prepare a dielectric powder containing lead oxide. ..

A sintering aid having a composition represented by 7Li ₂ O-42BaO-22B ₂ O ₃ -29SiO ₂ (mo1%) was added to this dielectric ceramic raw material powder (Japanese Patent Laid-Open No. 63-151658).
(Refer to Japanese Patent Laid-Open No. 2004-242242), and a polyvinyl butyral binder and an organic solvent were added and wet mixed for 16 hours in a ball mill to prepare a slurry. continue,
The thickness of this slurry is 35 μm by the doctor blade method.
m green sheet was molded.

Then, an electrode paste made of copper alloy powder adjusted to have the composition shown in Table 1 was printed on the ceramic green sheet to form internal electrodes. Then, they were laminated in a structure as shown in FIG. 1 and thermocompression bonded to obtain a laminated body.

[0015]

[Table 1]

[0016]

[Table 2]

The laminate thus obtained was heated to 350 ° C. in an N ₂ atmosphere to burn the binder,
Firing was performed at 850 to 1000 ° C. for 2 hours in a reducing atmosphere using a mixed gas of N ₂ , H ₂ and H ₂ O, CO ₂ , CO and the like. After firing, apply silver paste to both end faces of the fired body, and
₂ baked at 800 ° C. in an atmosphere to form an external electrode.
The dimensions and structure of the monolithic ceramic capacitor thus obtained are as follows.

[0018] Regarding the obtained multilayer ceramic capacitor samples, 2
Capacitance (C) at 1kHz and 1Vrms at 5 ° C
And the dielectric loss (tan δ) were measured. Further, using an insulation resistance meter, after applying a voltage of 50 V for 2 minutes, the insulation resistance (R) was measured. After that, the chips were hardened with a resin, polished, and observed under a microscope at a magnification of 200 to examine the presence or absence of delamination.

The firing is carried out in an oxygen partial pressure atmosphere shown in FIG. 2, specifically, in the center of the region shown by the reaction formula of 4Cu + O ₂ = 2Cu ₂ O and 2Pb + O ₂ = 2PbO shown in FIG. Partial pressure (see C in Fig. 2), and 4Cu + O
₂ = ₂ Cu ₂ O 0.5 than the oxygen partial pressure shown in the reaction formula
The atmosphere was controlled to the oxygen partial pressure on the digit oxidation side (see B in FIG. 2) and the oxygen partial pressure on the digit digit oxidation side (see A in FIG. 2). The results are shown in Table 2. Note that each of the 200 samples was used for evaluation, and the values in Table 2 are average values of units other than units that cannot be measured due to a short circuit. In addition, the samples marked with * in Tables 1 and 2 are other than the products of the present invention.

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

[Table 5]

[0023]

[Table 6]

[0024]

[Table 7]

[0025]

[Table 8]

In the present invention, Si, A in the copper alloy
The reason for limiting the contents of 1, Be, Mg and Zn is as follows. As is clear from Table 2, when Si, Al, Be, Mg and Zn are not contained in the internal electrode (Sample No. 1), that is, the conventional copper electrode is fired under the atmospheric condition C Unnecessary diffusion of copper, which is an internal electrode, occurs, resulting in a defective dielectric insulation resistance value (resistance value R ≦ 1 × 10
^In the case of ⁸ Ω or in the case of short circuit, the resistance value was considered to be defective), and defects such as delamination due to oxidative expansion during debinding were generated.

On the other hand, Si, Al, B in the internal electrode
At least one of e and Mg is 0.01 wt% or more (Sample Nos. 2, 6, 10, 14), or Zn is 1.
When it was contained in an amount of 0 wt% or more (Sample No. 18), the oxidation resistance of the copper electrode was improved, and the resistance value failure and delamination were suppressed. When the Si content is more than 2.5 wt% (Sample Nos. 5, 21, 40), or when the Mg content is more than 0.8 wt% (Sample Nos. 16, 3)
In 4), on the contrary, the oxidation resistance was lowered, and in any atmosphere, delamination occurred due to oxidative expansion of the internal electrodes, resulting in a large decrease in capacitance. In addition, a short circuit defect and a resistance value defect also occurred.

When the Al content is more than 16.0 wt% (Sample No. 9), the Be content is 4.0 wt%.
% (Sample No. 13) or Zn content is more than 59.5 wt% (Sample No. 20)
In, the internal electrodes were not completely alloyed and aggregated in a ball shape, resulting in disconnection of the internal electrodes, which significantly reduced the capacitance. In addition, delamination also occurred and short circuit defects occurred.

From the above results, the additive element contents of Si, Al, Be, Mg and Zn in the copper alloy used for the internal electrodes are as follows: Si: 0.01 to 2.5 wt% Al: 0.01 to 16 0.0 wt% Be: 0.01 to 4.0 wt% Mg: 0.01 to 0.8 wt% Zn: 1.0 to 59.5 wt%

As described above, in the monolithic ceramic capacitor according to the present invention, even if firing is carried out at an oxygen partial pressure higher than the oxygen partial pressure range shown in FIG. 3, metal oxides such as copper oxide generated by the oxidation of electrodes are formed. There was no decrease in device resistance due to diffusion into the dielectric, and no decrease in capacitance due to the occurrence of delamination, etc. On the contrary, the reduction of the dielectric was suppressed and the characteristics were improved. Further, the formation of the protective oxide by the additive elements of Si, Al, Be, Mg and Zn improved the adhesion strength and suppressed the occurrence of delamination.

In addition, in the above-mentioned embodiment, the forming method of forming the paste into the paste and screen-printing is shown as the method of forming the internal electrodes, but the present invention is not limited to this, and the vapor deposition method,
Even if a plating method or the like is used, the same effect can be obtained. Further, in the above description, the embodiment in which the present invention is applied to the laminated ceramic capacitor has been described, but the present invention can be applied to general laminated ceramic electronic components other than the laminated ceramic capacitor. For example, the present invention can be applied to any laminated electronic component such as a laminated CR composite component, an inductor or a varistor. Moreover, it is not always necessary that all of the ceramic sintered bodies are non-reducing ceramic materials, and only at least a part of the ceramic sintered body layers contacting the internal electrodes made of the copper alloy are made of non-reducing ceramic materials as described above. If configured, the effect of the present invention can be obtained.

[0032]

As is apparent from the above description, according to the present invention, since the inexpensive copper alloy is used as the material of the internal electrodes, the material cost can be remarkably reduced as compared with the conventional electronic parts using the noble metal. You can Moreover, Si, A
Since at least one of l, Be, Mg, and Zn is added to the copper alloy in a predetermined weight ratio, the oxidation resistance is improved compared to the conventional pure copper electrode, and firing in a high oxygen partial pressure is possible. Accordingly, it is possible to provide a highly reliable multilayer electronic component having a high insulation resistance, improving the leakage property with the ceramic layer by the additional element protective oxide generated at the electrode interface, and having a low delamination occurrence rate. You can

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a monolithic ceramic capacitor as an embodiment of the present invention.

FIG. 2 is a graph showing a firing atmosphere of the monolithic ceramic capacitor shown in FIG.

FIG. 3 is a graph showing the relationship between oxygen partial pressure of lead and copper and temperature.

[Explanation of symbols]

 1 ... Internal electrode 2 ... Dielectric ceramic 3 ... External electrode

Claims (1)

[Claims] 1. A multilayer electronic component comprising a ceramic sintered body obtained by integrally firing a plurality of ceramic green sheets laminated with at least one internal electrode interposed therebetween, wherein the ceramic is a ceramic sintered body. At least a part of the sintered body is composed of a non-reducing ceramic material, and the internal electrodes include Si: 0.01 to 2.5 wt% Al: 0.01 to 16.0 wt% Be: 0.01. -4.0 wt% Mg: 0.01-0.8 wt% Zn: 1.0-59.5 wt% An oxidation resistant copper alloy containing at least one element as an additive element is used. Mold electronic components.