JPH07109178A - Defatting of formed ceramics - Google Patents

Abstract

PURPOSE:To enable high-efficiency defatting inexpensively in lowered pollution, as the occurrence of defects is inhibited in the inner structure and the residual carbon can be reduced in the final sintered product, in the defatting process for molded ceramics containing organic binder. CONSTITUTION:In the process for defatting molded ceramics containing organic binder, said binder is removed by the decomposition with heat at a temperature lower than 1000 deg.C in 100vol.% steam atmosphere or in an inert gas atmosphere containing 90 to 99.9vol.% of steam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a degreasing method for an electrode-ceramic integrated sintering type electronic component such as a laminated ceramic capacitor, that is, a method for degreasing a ceramic molded body.

[0002]

2. Description of the Related Art In recent years, with the development of ultra-small, thin and lightweight electronic devices such as radios, microcassette recorders, electronic tuners, video cameras, etc., there is a strong demand for miniaturization and large capacity of electronic components used as circuit elements. It's starting to happen. A monolithic ceramic capacitor, for example, has been known as a ceramic electronic component of an integrally sintered type in which electrodes and ceramics satisfy these requirements. As a method for manufacturing a monolithic ceramic capacitor, a slurry composed of a dielectric powder, a binder, a plasticizer, and an organic solvent is used to form a ceramic dielectric having a thickness of several tens of μm on an organic film by a doctor blade method to obtain a green sheet. To make.
After stacking multiple sheets with the internal electrodes printed on this sheet, a laminated molded body is produced by pressure bonding, and then,
After cutting, degreasing, and firing into chips, an external electrode is formed (“Insulated Dielectric Ceramic” published by CMC Co., Ltd., edited by Tadashi Shiozaki, p. 211-227, 1985).

In the prior art, the method of degreasing a ceramic molded body is to suppress the internal structural defects of the product due to the heat generated by the rapid oxidative decomposition of the organic binder. Further, the ceramic molded body is an integrally sintered type ceramic of the electrode and the ceramic. In the case of electronic parts, in order to suppress internal structural defects in the final product due to electrode oxidation and volume expansion, heating is performed at a temperature above the decomposition temperature of the organic binder in a non-oxidizing gas atmosphere. It is being appreciated. Furthermore, in the above-mentioned method for degreasing a ceramic molded body, the removal of the organic binder is insufficient, and it remains as residual carbon in the final sintered body, and there is a problem that the characteristics of the product deteriorate due to the residual carbon. . For example, a monolithic ceramic capacitor has a problem of inducing an early decrease in insulation resistance value. In order to solve this problem, the present inventor has proposed a method for degreasing a ceramic molded body that can obtain a product having excellent characteristics while suppressing internal structural defects of the ceramic molded body. We have proposed a degreasing method for ceramic moldings (patent pending), which is characterized by heat treatment at 1000 ° C or less in a volatile gas atmosphere, and have conducted studies.

[0004]

However, although the above-mentioned conventional method can obtain a product having excellent characteristics while suppressing internal structural defects, on the other hand, harmful gas generated by thermal decomposition of the organic binder is removed. It has a problem that a large amount of non-oxidizing gas containing it is discharged, and that a relatively expensive non-oxidizing gas is used to increase the manufacturing cost and eventually increase the unit price of the product. . In order to solve the above problems, it is an object of the present invention to provide a method for producing a product having excellent characteristics while suppressing internal structural defects, at a low cost, without generating a large amount of harmful exhaust gas. It is a thing.

[0005]

In order to achieve the above object, the present invention decomposes and removes the organic binder by heat treatment at 1000 ° C. or lower in an atmosphere of 100% by volume of steam. Alternatively, the organic binder is decomposed and removed by heat treatment at 1000 ° C. or lower in a non-oxidizing gas atmosphere containing 90 to 99.9% by volume of steam. The non-oxidizing gas is nitrogen gas, carbon dioxide gas, inert gas, or a mixed gas of the above gases, which is a degreasing method for a ceramic molded body.

The above-mentioned ceramic molded body is Pd or Pd
Electrodes and ceramics integrally-sintered ceramic electronic parts that use an alloy whose main metal is Pd, or multilayer ceramic capacitors that use Pd or an alloy whose main metal is Pd as an electrode. Further, the ceramic molded body is an integrally sintered type ceramic electronic component of an electrode and a ceramic whose electrode is Ni or an alloy whose main metal is Ni, or a laminated ceramic whose electrode is an alloy whose main metal is Ni or Ni. A degreasing method for a ceramic molded body, which is a capacitor.

[0007]

The present inventor has found that the thermal decomposition reaction of the organic binder is promoted by introducing water vapor in the thermal decomposition reaction of the organic binder. That is, when the organic binder, which is a high molecular weight organic compound, is thermally decomposed, water vapor acts on the organic binder to promote the lowering of the molecular weight of the generated decomposition gas. Further, since the thermal decomposition reaction of the organic binder is an endothermic reaction, it is a common non-oxidizing gas (N ₂ , CO ₂ , Ar, He).
Water vapor, which has a larger sensible heat than that, also acts as a heat source.

Degreasing in a non-oxidizing gas atmosphere containing water vapor, which has been carried out in the conventional manufacturing method, suppresses internal structural defects of the product due to heat generation due to abrupt oxidative decomposition of the organic binder, and the ceramic molded body is used as an electrode. In the case of a ceramic electronic component of the integral sintering type of ceramics and ceramics, the organic binder can be sufficiently removed while suppressing the occurrence of internal structural defects in the final product due to the oxidation and volume expansion of the electrodes. A large amount of non-oxidizing gas including harmful gas generated by thermal decomposition of the binder is discharged, and the cost is high. However, if the degreasing method according to the present invention is used, in an atmosphere of 100% by volume of steam or in a non-oxidizing gas atmosphere containing 90 to 99.9% by volume of steam,
As in the conventional degreasing method, there is no heat generation due to the rapid oxidative decomposition of the organic binder, and when the ceramic molded body is a ceramic electronic component of the integrally sintered type of electrode and ceramic, the electrode oxidizes and the volume expands. Therefore, the occurrence of internal structural defects is suppressed. Further, the efficient thermal decomposition characteristics of the organic binder due to the introduction of the water vapor are maintained, and the organic binder is sufficiently removed. Further, the decomposed gas of relatively low molecular weight generated by the thermal decomposition of the organic binder is mostly dissolved in the supplied steam, so that harmful exhaust gas is significantly reduced. Further, in general, non-oxidizing gas such as N ₂ , CO ₂ , Ar and He which is more expensive than steam is not used, or even if it is used, the amount of non-oxidizing gas used is smaller than that in the conventional method. It is possible to reduce the manufacturing cost and eventually the unit price of the product.

[0009]

EXAMPLE A method of manufacturing a monolithic ceramic capacitor according to a first example of the present invention will be described below. In the first embodiment, a commercially available Pd electrode was used as an electrode on a dielectric slurry composed of a dielectric powder containing BaTiO ₃ as a main component and an organic binder and having a thickness of 30 μm formed by a doctor blade method and then dried. A green sheet was prepared by forming the paste to a thickness of 3 μm by a screen printing method. After stacking 20 of the green sheets, a laminated molded body was produced by pressure bonding. The organic binder component contained in the laminated compact was 10% by weight. As a first embodiment,
The laminated molded body is heated at a heating rate of 200 ° C / min and a maximum temperature of 600
The organic binder was removed by heat treatment using a temperature schedule of ° C and a holding time of 2 hours.

[0010]

[Outer 1]

The exhaust gas accompanying the removal of the organic binder in the embodiment of the present invention was significantly smaller than that in the conventional example.

[0012] The residual carbon amount of the sample was measured by both organic binder removal methods, and a comparative study was conducted. (Table 1) shows the result of the residual carbon amount after removing the organic binder and the exhaust gas amount in each case. It was confirmed that the first example according to the present invention has the same effect of removing the organic binder as that of the conventional example and reduces harmful exhaust gas.

[0013]

[Table 1]

Further, both samples were subjected to a N ₂ gas atmosphere at 1320 ° C.
It was fired for 2 hours to obtain a monolithic ceramic capacitor. Observation of the occurrence of internal structural defects in the multilayer ceramic capacitor and insulation resistance life test (test conditions 150 ° C, DC128
V was applied) and the characteristics were compared. The results are shown in (Table 2). In Table 2, the occurrence status of internal structural defects is
The occurrence status is shown for 20 samples, and the life test results show that in all cases, the initial value was 1 × 10 ⁹ Ω or more, and half of the 20 samples were 1 × 10 ⁷ Ω or less. Showed the time.

[0015]

[Table 2]

From the results shown in Table 2, it can be seen that the occurrence of internal structural defects in the degreasing method according to the first embodiment is suppressed. It was also confirmed that the life characteristics of the product were comparable to those of the conventional example. In addition, N ₂ , which is generally more expensive than steam,
It goes without saying that the manufacturing cost was reduced because no non-oxidizing gas such as CO ₂ , Ar or He was used.

Next, as a second embodiment, the same laminated compact as in the first embodiment is heat treated using a temperature schedule of a temperature rising rate of 200 ° C./min, a maximum temperature of 600 ° C. and a holding time of 2 hours. Thus, the organic binder was removed.

[0018]

[Outside 2]

The exhaust gas accompanying the removal of the organic binder in the second embodiment according to the present invention was significantly smaller than that in the conventional example.

The amount of residual carbon in the sample by each of the above degreasing methods was measured and a comparative study was conducted. Table 3 shows the result of the residual carbon amount after removing the organic binder and the exhaust gas amount in each case. The second embodiment according to the present invention has the same effect of removing the organic binder as compared with the conventional example.
It was also confirmed that harmful exhaust gas was reduced.

[0021]

[Table 3]

Further, both samples were subjected to N ₂ gas atmosphere at 1320 ° C.
It was fired for 2 hours to obtain a monolithic ceramic capacitor. Observation of the occurrence of internal structural defects in the multilayer ceramic capacitor and insulation resistance life test (test conditions 150 ° C, DC128
V was applied) and the characteristics were compared. The results are shown in (Table 4).
In Table 4, the occurrence of internal structural defects is shown for each of the 20 samples according to each example, and the life test result shows that the initial value is 1 in any of the examples.
Of the 20 samples that were more than × 10 ⁹ Ω, half were 1 × 10 ⁷ Ω
The time when it became below was shown.

[0023]

[Table 4]

From the results shown in Table 4, it can be seen that the occurrence of internal structural defects is suppressed by any of the degreasing methods according to the second embodiment. It was also confirmed that the life characteristics of the product were comparable to those of the conventional example. Further, it is needless to say that the manufacturing cost has been reduced because a large amount of non-oxidizing gas such as N ₂ , CO ₂ , Ar and He, which is generally more expensive than steam, is not used.

In the present embodiment, the monolithic ceramic capacitor having Pd as the electrode was taken up, but the ceramic molded body is an integrally sintered type ceramic electronic component of the electrode and the electrode having Ni or an alloy whose main metal is Ni. Even in such a case, if the degreasing method according to the present invention is used, due to the same effect as in the present embodiment, heat generation due to rapid oxidative decomposition of the organic binder does not occur, and oxidation of the electrode does not occur. Therefore, it is possible to suppress the occurrence of internal structural defects due to these factors. Also, by using water vapor, the organic binder can be efficiently and sufficiently removed, and excellent properties can be secured in the final product.
Further, N ₂ , CO ₂ , Ar, and He, which are generally more expensive than water vapor,
Since the amount of non-oxidizing gas such as the above can be reduced, the manufacturing cost can be reduced and the amount of exhaust gas can be reduced. Further, although the monolithic ceramic capacitor is taken up in the present embodiment, it is needless to say that the same effect can be obtained even when applied to other monolithic electronic parts such as a monolithic actuator and a monolithic varistor.

[0026]

As is apparent from the above examples, according to the method for degreasing a ceramic molded body according to the present invention, the method for removing the organic binder from the ceramic molded body is performed with 100% steam.
In a non-oxidizing gas atmosphere containing 90% to 99.9% by volume of steam or 90% to 99.9% by volume of water vapor, heat treatment at 1000 ° C or less suppresses the occurrence of internal structural defects due to electrode oxidation and It has become possible to reduce the residual carbon in the sintered body at a low cost without generating a lot of harmful exhaust gas. Therefore, according to this manufacturing method, there is an effect that an integrally sintered type ceramic electronic component of an electrode and a ceramic having excellent characteristics can be produced with low pollution and at low cost.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Emiko Igaki Emiko 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Wataru Sakamoto 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. A method for degreasing a ceramic molded body containing an organic binder, comprising:
A method for degreasing a ceramic molded body, which comprises performing a heat treatment at 000 ° C or lower. 2. A degreasing method for a ceramic molded body containing an organic binder, wherein the ceramic molded body is degreased by heat treatment at 1000 ° C. or lower in a non-oxidizing gas atmosphere containing 90 to 99.9% by volume of steam. Method. 3. The degreasing method for a ceramic molded body according to claim 1, wherein the non-oxidizing gas is nitrogen gas, carbon dioxide gas, an inert gas or a mixed gas of the gases. 4. The ceramic molded body is a ceramic electronic component of an integral sintering type of an electrode and a ceramic having Pd or an alloy containing Pd as a main metal as an electrode. Degreasing method for ceramic molded body. 5. The ceramic molded body is a ceramic electronic component of integral sintering type of an electrode and a ceramic having Ni or an alloy containing Ni as a main metal as an electrode. Degreasing method for ceramic molded body. 6. The degreasing method for a ceramic molded body according to claim 1, wherein the ceramic molded body is a monolithic ceramic capacitor having electrodes of Pd or an alloy containing Pd as a main metal. 7. The degreasing method for a ceramic molded body according to claim 1, wherein the ceramic molded body is a laminated ceramic capacitor having Ni or an alloy containing Ni as a main metal as electrodes.