JPH06151237A - Manufacture of ceramic electronic part - Google Patents

Abstract

(57) [Abstract] [Purpose] In a ceramic electronic component obtained by integrally sintering Pd or Pd alloy ceramics, including internal structural defects and insulation resistance caused by the amount or method of treatment during manufacturing. It is an object of the present invention to provide a firing method with high reproducibility by suppressing variations in various electrical characteristics. [Structure] Pd or an alloy electrode containing Pd as a main metal and a ceramic are integrally sintered, and fired in an atmosphere in which Pd does not oxidize in a temperature range in which Pd oxidizes in an air atmosphere,
After that, the atmosphere is replaced, and after detecting that the residual C content is completely burned by the thermocouple 7 etc., the temperature is raised and the ceramic is sintered to suppress the occurrence of internal structural defects, and various electrical characteristics. It is possible to manufacture a ceramic electronic component having uniform and excellent reproducibility.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, an integrally sintered type ceramic electronic component having Pd or an alloy containing Pd as a main metal as an electrode has been fired in the atmosphere. When fired in the atmosphere, Pd is oxidized at a temperature of up to 820 ° C to become an oxide, but decomposes at a temperature of 820 ° C or higher to be transformed into Pd metal, and thus fired at a temperature of 820 ° C or higher. Even if it is co-fired with the ceramic to be formed, it is formed as a Pd metal or Pd alloy electrode. From this, for example, in the case of a monolithic ceramic capacitor, Pd is often used for internal electrodes. In this case, a ceramic chip and an electrode paste are alternately stacked to make a green chip, and after debinding, it is exposed to the atmosphere. It is fired in Pd inside
The method of forming the electrodes has been taken.

[0003]

When firing a green chip of a monolithic ceramic capacitor, which is one of the ceramic electronic components having Pd or an alloy electrode containing Pd as a main metal, Pd of the internal electrode is changed during the firing process. Is oxidized and the volume is expanded, and the volume of the internal electrode portion is increased. Therefore, internal structural defects are often generated after firing, and there is also a method of firing in an inert atmosphere or in a vacuum in the temperature range where Pd is oxidized and firing in the air in a temperature range above the decomposition temperature of PdO. However, in the firing in an inert atmosphere, the binder is not sufficiently removed depending on the treatment amount or the treatment method, and the residual C content remains in the chip up to a high temperature range (ceramic sintering temperature range). There is a problem that variations in various electrical characteristics such as defects and insulation resistance are likely to occur.

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 the internal structural defects of the ceramic electronic component such as a monolithic ceramic capacitor and the fluctuation of electrical characteristics. And

[0005]

In order to achieve the above object, the manufacturing method of the present invention is carried out by firing in an atmosphere in which Pd does not oxidize in the temperature range where Pd oxidizes when the ceramic and the electrode are integrally sintered. Then, the atmosphere is replaced, and after confirming that the residual C content is completely removed, the temperature is raised to sinter the ceramic.

[0006]

The integrally 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 content remains in the molded body up to a high temperature range. It can be experimentally confirmed as follows. In a thermogravimetric analysis and differential thermal analyzer (TG-DTA) of a normal green chip, in a temperature range in which Pd is oxidized, a temperature range in which PdO is reduced to Pd in nitrogen (900
(Fig. 1) DTA of (Fig. 1)
The present inventor experimentally confirmed that an exothermic peak due to combustion of the residual C content is observed when converting from a nitrogen atmosphere to an air atmosphere as shown by the curve. If the residual C content observed in this way is not completely removed and remains up to the sintering temperature range of the ceramic, it may cause variations in electrical characteristics such as the insulating property of the product. Therefore, in the temperature range in which Pd is oxidized in the air, firing is performed in an atmosphere such as inert gas or in a vacuum in which Pd is not oxidized, and in the temperature range above the temperature at which PdO is reduced to Pd, firing is performed in the air. In this case, various gas sensors are set inside the sheath for heat treatment, for example, inside a thermocouple or a furnace for heat treatment, whereby the residual C content is converted in a temperature range in which the atmosphere is converted from an inert atmosphere into the atmosphere. Since the removal control can be thoroughly performed by each sensor, it can be fired after confirming that the residual C content does not exist completely and uniformly regardless of the amount of processing, and it is an excellent ceramic electronic component with uniform electrical characteristics such as insulation. Can be manufactured with good reproducibility.

[0007]

EXAMPLES Examples of the present invention will be described in detail below. 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 size of 0.4 μm was used as a metal component.
An electrode paste using d powder was printed to a thickness of 3 μm to prepare a green chip having 30 effective layers. This green chip is heated in nitrogen at 100 ° C / hr to 400 ° C.
After removing the binder at 1320,
Firing was performed up to ° C, and the insulation resistance value was measured.

(1) Firing up to 900 ° C. in nitrogen. 900 ° C
Then, switch to the atmosphere, and continue firing in the air from 900 ° C to 1320 ° C. (2) Firing in nitrogen up to 900 ° C. After depressurizing while maintaining at 900 ° C, the atmosphere was replaced, and as shown in (Fig. 2), this operation was continued until the heat generation due to the combustion of the residual C was no longer confirmed by the thermocouple 7 set in the firing sheath 4 in the firing furnace 3. After repeating the above, firing 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 temperature rising rate was 200 ° C./hr in all cases. As a result,
In the firing method of (1), the average value of measured insulation resistance is 8 × 1.
In contrast to the value of 0 ⁹ Ω (average of 500 pieces), the firing method of the method (2) of this example is 1 × 10 ¹¹ Ω (500).
The average of the number) and the dielectric properties of the ceramic dielectric layer are improved.

(Example 2) The same green chip as in Example 1 was debindered as in Example 1 and then fired at 1320 ° C by the following two methods to measure the insulation resistance value. I went.

(1) Firing in nitrogen up to 900 ° C. 900 ° C
Then, switch to the atmosphere, and continue firing in the air from 900 ° C to 1320 ° C. (2) Firing in nitrogen up 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 rate of temperature rise was 2
It was set to 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) of this example was 9
The result was × 10 ¹⁰ Ω (average of 500 pieces), and the same effect as in Example 1 was confirmed.

That is, in the temperature range in which the atmosphere is converted from the inert atmosphere to the atmosphere, the in-furnace management for completely and uniformly removing the residual C content can be thoroughly performed by each sensor, so that various electrical characteristics can be obtained. It can be made uniform, and such a result will be obtained.

It goes without saying that the same result can be obtained by using an alloy electrode containing Pd as a main metal in place of the Pd electrode in the above-mentioned embodiment.

[0015]

As is apparent from the above description of the embodiment, the manufacturing method according to the present invention is a single sintering of Pd or an alloy electrode containing Pd as a main metal and a ceramic, and the temperature at which Pd oxidizes in an air atmosphere. When the region is fired in an atmosphere in which Pd does not oxidize, and then fired in the air, the residual C content is completely and uniformly irrespective of the treatment amount in the temperature range in which the atmosphere is converted from the inert atmosphere to the air. Since the control for removal can be thoroughly performed by each sensor, it is possible to reproducibly manufacture an excellent ceramic electronic component having no internal structural defect and uniform electrical characteristics.

[Brief description of drawings]

FIG. 1 is a view 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]

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

Front page continuation (72) Inventor Takashi Iguchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Yoichi Okinaka, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A method of integrally sintering a ceramic electrode and an electrode of Pd or an alloy containing Pd as a main metal, the method comprising:
A method for producing a ceramic electronic component in which a temperature range in which d is oxidized in an air atmosphere is fired in an atmosphere in which Pd is not oxidized, and then the atmosphere is replaced, and after the remaining C is completely burned, the temperature is raised to sinter the ceramic . 2. The method of manufacturing a ceramic electronic component according to claim 1, wherein the ceramic electronic component is a monolithic ceramic capacitor. 3. The method for producing a ceramic electronic component according to claim 1, wherein the atmosphere in which Pd is not oxidized is an inert gas or vacuum.