JP3098118B2 - Manufacturing method of ceramic electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a sintered body of an electrode and a ceramic for a ceramic electronic component such as a multilayer ceramic capacitor.

[0002]

2. Description of the Related Art Conventionally, an integrally sintered type ceramic electronic component using Pd or an alloy containing Pd as a main metal as an electrode has been fired in the atmosphere. When calcined in the atmosphere, Pd oxidizes at temperatures up to 820 ° C. to form oxides, but decomposes at 820 ° C. or more and turns into Pd metal, so that it is calcined at 820 ° C. or more. Even if co-firing with the ceramic to be performed, it is formed as a Pd metal or Pd alloy electrode. For this reason, for example, in the case of a multilayer ceramic capacitor, Pd is often used for an internal electrode. In this case, a green chip is formed by alternately stacking ceramic sheets and electrode pastes, and after debinding, a green chip is formed. Baking with Pd inside
A method of forming an electrode has been used.

[0003]

When firing a green chip of a multilayer ceramic capacitor, which is one of the ceramic electronic components having Pd or an alloy electrode containing Pd as a main metal, the Pd of the internal electrode is reduced during the firing process. And the volume expands, and the volume of the internal electrode portion increases. For this reason, internal structural defects often occur after firing, and firing in an inert atmosphere or in a vacuum in a temperature range where Pd is oxidized, and firing in the air in a temperature range equal to or higher than the decomposition temperature of PdO may be performed. However, in the sintering in an inert atmosphere, the binder removal is not sufficiently performed depending on the treatment amount or the treatment method, and the residual C component remains in the chip up to a high temperature region (ceramic sintering temperature region). There has been a problem that electrical characteristics such as defects and insulation resistance tend to fluctuate.

An object of the present invention is to solve the above-mentioned problems and to provide a method of manufacturing a ceramic electronic component capable of suppressing internal structural defects and variations in electrical characteristics of a ceramic electronic component such as a multilayer ceramic capacitor. And

[0005]

In order to achieve the above-mentioned object, the manufacturing method of the present invention is characterized in that the temperature range in which Pd is oxidized when the ceramic and the electrode are integrally sintered is fired in an atmosphere in which Pd is not oxidized. , Then PdO reduced to Pd in air
The atmosphere is replaced with air in a temperature range in which the residual C content is completely removed, the temperature is raised, and the ceramic is sintered.

[0006]

The integrated molded product of the electrode and the ceramic contains various organic binders as components before firing, but when firing in an inert atmosphere, residual C remains in the molded body up to a high temperature range. It can be confirmed experimentally as follows. In a temperature range where Pd is oxidized, a temperature range where PdO is reduced to Pd in nitrogen (900) is measured by a thermogravimetric analysis and a differential thermal analyzer (TG-DTA).
(° C) and above, when measurement is performed in the atmosphere, the DTA of (Fig. 1)
The inventor experimentally confirmed that an exothermic peak due to combustion of the residual C was observed when converting from a nitrogen atmosphere to an atmospheric atmosphere as shown by the curve. If the residual C content thus observed is not completely removed but remains up to the sintering temperature range of the ceramic, it causes a change in electrical characteristics such as insulating properties of the product. Therefore, in the temperature range where Pd is oxidized in the atmosphere, firing is performed in an atmosphere in which Pd is not oxidized, such as in an inert gas or in a vacuum, and in the temperature range above the temperature at which PdO is reduced to Pd, firing is performed in the air. In this case, for example, various gas sensors are set inside the sheath for performing the heat treatment, for example, inside the thermocouple or the furnace for performing the heat treatment, so that the temperature of the atmosphere is changed from the inert atmosphere to the atmosphere. Excellent ceramic electronic components with uniform electrical properties such as insulation, because removal control can be thoroughly performed by each sensor, and firing can be performed completely and uniformly after confirming the absence of residual C, regardless of the processing amount. Can be manufactured with good reproducibility.

[0007]

Embodiments of the present invention will be described below in detail. Example 1 A 30 μm-thick green sheet made of a dielectric powder containing barium titanate as a main component and an organic binder was prepared, and P having an average particle diameter of 0.4 μm was used as a metal component.
The electrode paste using the d powder was printed to a thickness of 3 μm to produce a green chip including 30 effective layers. The temperature of this green chip was increased in nitrogen at 100 ° C./hr,
After debinding, the following two methods are used to
C., and the insulation resistance was measured.

(1) Firing in nitrogen to 900 ° C. 900 ° C
Then, it is fired in air from 900 ° C to 1320 ° C. (2) Firing in nitrogen to 900 ° C. After reducing the pressure while maintaining the temperature at 900 ° C., the atmosphere is replaced with the atmosphere. As shown in FIG. 2, this operation is performed until the heat generated by the combustion of the residual C is no longer confirmed by the thermocouple 7 set in the firing sheath 4 in the firing furnace 3. , And then fired in the air from 900 ° C to 1320 ° C.

In FIG. 2, 5 is a gas valve, 6 is CO, C
It is a sensor such as O ₂ . In these experiments, the heating rate was 200 ° C./hr in each case. As a result,
In the firing method (1), the average value of the measured insulation resistance is 8 × 1.
0 ⁹ Omega contrast became (500 average) and, at the firing method of a method of this Example ^{(2) 1 × 10 11 Ω} (500
And the insulating properties of the ceramic dielectric layer were improved.

(Embodiment 2) The same green chip as in Embodiment 1 was subjected to binder removal in the same manner as in Embodiment 1, and then fired to 1320 ° C. by the following two methods to measure the insulation resistance value. Was done.

(1) Firing in nitrogen to 900 ° C. 900 ° C
Then, it is fired in air from 900 ° C to 1320 ° C. (2) Firing in nitrogen to 900 ° C. Substituted atmosphere while maintained at 900 ° C., after CO for detecting the CO and CO ₂ in the atmospheric gas, the CO by CO ₂ sensor, CO ₂ concentration decreased below the detection limit in air firing to 1320 ° C. from 900 ° C. .

In each of these experiments, the heating rate was 2
00 ° C-hr. As a result, the firing method of (1) was 8 × 10 ⁹ Ω (average of 500 pieces) as in Example 1, whereas the firing method of (2), which is the method of this example, was ⁹ × 10 ⁹ Ω.
× 10 ¹⁰ Ω (average of 500 pieces), and the same effect as in Example 1 was confirmed.

That is, in the temperature range where the atmosphere is converted from the inert atmosphere to the atmosphere, the inside of the furnace for completely and evenly removing the residual C content can be thoroughly controlled by each sensor. Such a result can be obtained.

In the above-described embodiment, it goes without saying that the same result can be obtained by using an alloy electrode containing Pd as a main metal instead of the Pd electrode.

[0015]

As is apparent from the above description of the embodiment, the manufacturing method according to the present invention is a method of integrally sintering an electrode of Pd or an alloy containing Pd as a main metal and a ceramic.
The temperature range in which Pd is oxidized in the atmosphere is Pd
Firing in an atmosphere that does not oxidize, and then Pd in air
Atmosphere is replaced in the temperature range where O reduces to Pd, and residual C
After it is completely burned, it heats up and sinters the ceramic.
In the temperature range where the atmosphere is converted from the inert atmosphere to the atmosphere, regardless of the processing amount, the sensor can completely and uniformly manage the removal of the residual C component by each sensor.
An object of the present invention is to make it possible to produce a ceramic electronic component excellent in reproducibility, which has no internal structural defects and uniform electric characteristics.

[Brief description of the drawings]

FIG. 1 is a diagram showing a thermogravimetric analysis (TG) -differential thermal analysis (DTA) measurement result of a green chip of a multilayer ceramic capacitor.

FIG. 2 is a sectional view showing a firing furnace and a firing sheath.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 DTA curve 2 TG curve 3 Firing furnace 4 Firing sheath 5 Gas valve 6 CO, CO ₂ sensor 7 Thermocouple

──────────────────────────────────────────────────の Continuing on the front page (72) Takashi Iguchi 1006 Kadoma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-62-106612 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01G 4/00-4/40 H01G 13/00-13 / 06

Claims (3)

(57) [Claims] 1. A method for integrally sintering an electrode of Pd or an alloy containing Pd as a main metal and a ceramic,
In the temperature range where d is oxidized in an air atmosphere, firing is performed in an atmosphere in which Pd is not oxidized, and then PdO is converted to Pd in an air atmosphere.
A method for producing a ceramic electronic component in which the atmosphere is replaced with air in a temperature range in which the residual C is completely burned, and after the residual C is completely burned, the temperature is raised and the ceramic is sintered. 2. The method according to claim 1, wherein the ceramic electronic component is a multilayer ceramic capacitor. 3. The method according to claim 1, wherein the atmosphere in which Pd is not oxidized is an inert gas or a vacuum.