JP3000781B2 - Method of firing ceramic compact containing high vapor pressure oxide - 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 firing a ceramic molded article containing a high vapor pressure oxide, and more particularly, to a ceramic molding for a product containing a high vapor pressure oxide when manufacturing a chip type multilayer ceramic capacitor or the like. When the body is placed in a refractory container and fired, the firing atmosphere is suitably controlled to prevent the loss of firing due to volatilization of the contained high vapor pressure oxide, thereby ensuring a product having a desired composition. To the method that makes it possible to obtain.

[0002]

2. Description of the Related Art To manufacture a multilayer ceramic capacitor, for example, after printing an internal electrode on a dielectric green sheet, punching it into a predetermined size, stacking the punched sheets, pressing them together, and matching the size of each chip. And cut it.
Next, the cut raw chips are placed on a ceramic firing table and fired at a temperature of 1000 to 1400 ° C. The fired chip is provided with terminal electrodes for internal electrode connection at both ends, and is further subjected to electroplating for improving solder heat resistance.

[0003] Conventionally, in firing the above-mentioned raw chips, if the raw chips contain volatile high vapor pressure oxides, the raw chips are placed on the raw chips in order to maintain a uniform firing atmosphere during firing. The pedestal is stacked in multiple stages, placed in a ceramic sagger, and fired in a sealed state.

[0004]

However, even when firing is carried out in a sealed state in a ceramic sagger, volatilization of high vapor pressure oxides cannot be reliably prevented. Due to evaporation of the vapor pressure oxide, a fired product having a desired composition cannot be obtained.

[0005] The firing varies depending on the position in the sagger, that is, the vertical position of the firing tables stacked in multiple stages, and the composition of the obtained fired product differs.

However, there are drawbacks that it is difficult to obtain the desired electrical characteristics, and that the product characteristics vary widely.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. A ceramic molded product for a product containing a high vapor pressure oxide is charged into a refractory container and heated in a sealed state. In a method of firing, there is provided a method of firing a ceramic molded body containing a high vapor pressure oxide, which can prevent a high vapor pressure oxide from volatilizing and can easily and efficiently obtain a fired product having a target composition. Aim.

[0008]

According to the first aspect of the present invention, there is provided a method for firing a ceramic compact containing a high vapor pressure oxide, comprising charging a ceramic compact for a product containing a high vapor pressure oxide into a refractory container. Then, in the method of heating and firing in a state where the container is sealed, the molded article for atmosphere control made of the high vapor pressure oxide or a material containing the high vapor pressure oxide is placed in the container. It is characterized by firing.

According to a second aspect of the present invention, there is provided a method for firing a ceramic molded body containing a high vapor pressure oxide, wherein the atmosphere controlling molded body is a sheet-shaped molded body and is laid in the container. A sheet of a high melting point oxide is placed on the sheet-like formed body for atmosphere control, and a ceramic formed body for the product is placed on the sheet and firing is performed. And

Referring to the drawings, a method for firing a ceramic compact containing a high vapor pressure oxide according to the present invention will be described in detail below.

FIG. 1 is a partially cutaway perspective view showing one embodiment of a method for firing a ceramic compact containing a high vapor pressure oxide according to the present invention.

In the method of the present embodiment, a sheet-like molded body is used as the atmosphere-controlling molded body 1, and the sheet-like atmosphere-controlling molded body is laid on the base plate 2A of the firing table 2, and A high-melting-point oxide sheet 3 is placed on the atmosphere control molded body 1, and a large number of ceramic molded bodies (raw chips in this embodiment) 4 for products are placed on the sheet 3. .

At the time of firing, the firing table 2 on which the ceramic molded body 4 is mounted is packed into a firing sagger mounted on a conveyor via a base plate (not shown), the upper lid is closed, and then, Conveyed by a conveyor to a firing furnace, for example, 1-2
The calcination is carried out at a temperature of 1000 to 1400 ° C. under atmospheric pressure for a time.

As a result, the high vapor pressure oxide contained in the atmosphere controlling compact 1 is volatilized during firing, and the firing atmosphere becomes a high concentration atmosphere of the high vapor pressure oxide. Volatilization of the high vapor pressure oxide from the body 4 is effectively prevented.

The ceramic compact 4 is placed on the high-melting-point oxide sheet 3 and does not come into contact with the baking table 2 or the atmosphere control compact 1, so that no reaction occurs with them.

In the present invention, the molded article for controlling atmosphere is
It is made of a material containing a high vapor pressure oxide or a high vapor pressure oxide contained in a ceramic molded body to be fired,
Usually, a ceramic green sheet having the same composition as the ceramic molded body to be fired is used.

On the other hand, the high-melting point oxide sheet may be any thermally and chemically stable sheet which can prevent a reaction between the ceramic molded body to be fired and the fired table or the atmosphere controlling molded body. In the case of (1), a ceramic green sheet mainly containing one or more of Al ₂ O ₃ , ZrO, MgO or the like is used.

The thickness of the sheet of the molded article for controlling atmosphere and the thickness of the sheet of the high melting point oxide are not particularly limited as long as sufficient strength can be ensured from the viewpoint of handleability and the like. In a normal case, the sheet of the molded article for atmosphere control and the sheet of the high-melting-point oxide are laminated and integrated for use.

The illustrated example is an embodiment of the present invention, and the present invention is not limited to the illustrated method unless it exceeds the gist.

For example, the shape of the molded article for controlling atmosphere is not limited to a sheet shape, but may be a thick plate shape. In addition, an arbitrary lump may be charged into a firing container together with a ceramic molded body for a product. Further, the sheet of the high-melting-point oxide may be in the form of a plate having a large thickness. The plate of the melting point oxide may not be used.

In the present invention, as a ceramic molded body for a product containing a high vapor pressure oxide to be fired, for example,
Lead-based, lithium-based and the like can be mentioned.

[0022]

According to the method of the present invention, since the molded body for controlling the atmosphere containing the high vapor pressure oxide is placed in a closed vessel together with the ceramic molded body for the product and calcined, the calcining atmosphere is The high vapor pressure oxide volatilized from the atmosphere control molded body provides an atmosphere containing a high concentration of the high vapor pressure oxide. For this reason, volatilization of the high vapor pressure oxide from the ceramic molded product for products is prevented, and it is possible to obtain a product having the target composition and the target characteristics and having no variation.

According to the method of the second aspect, it is possible to reliably prevent the reaction between the ceramic molded product for the product and the molded product for controlling the atmosphere, the firing jig and the like, and to obtain a better product.

[0024]

The present invention will be described more specifically with reference to the following examples and comparative examples.

Example 1 A raw chip made of a lead-perovskite-based ceramic dielectric was fired by the method shown in FIG. That is, A
A firing sheet (length 80) obtained by laminating a green sheet containing l ₂ O ₃ as a main component and a lead perovskite ceramic green sheet having the same composition as the raw chip.
mm, width 100 mm, thickness 250 μm)
0mm, width 105mm, thickness 5mm, leg length 9m
m), and about 700 raw chips were placed on the firing sheet.

A plurality of baking tables on which the raw chips are mounted via the baking sheet are 140 m in length.
m in a sagger, and in a firing furnace under atmospheric pressure, 110
It was baked at 0 ° C. for 2 hours.

Comparative Example 1 A green chip was fired in the same manner as in Example 1 except that the firing sheet was not used.

Discussion In Example 1 and Comparative Example 1, 1000 chips each obtained by firing were sampled, and the presence or absence of color unevenness on the chip surface was observed with a microscope. As a result, in Comparative Example 1,
About 30 to 40% of the firing unevenness occurred inside and around the firing table, but in Example 1, no firing unevenness occurred.
In addition, when the electrical characteristics of the fired unevenness-producing chip obtained in Comparative Example 1 were measured, it was found that the capacity was deteriorated. From this, it is clear that the firing sheet according to the present invention functions effectively, and according to the method of the present invention, a product with high characteristics can be obtained with good yield.

[0029]

As described above in detail, according to the method of the present invention, in firing a ceramic compact containing a high vapor pressure oxide, a composition change due to volatilization of the high vapor pressure oxide during firing is prevented. A product having an intended composition and desired properties can be easily and efficiently obtained at a high yield without variation among products. According to the method of the second aspect, it is possible to reliably obtain a product with higher characteristics.

[0030]

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing one embodiment of a method for firing a ceramic compact containing a high vapor pressure oxide according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Atmosphere control molded object 2 Firing table 3 High melting point oxide plate 4 Ceramic molded object

Claims (2)

(57) [Claims] 1. A method of charging a ceramic molded product for a product containing a high vapor pressure oxide into a refractory container and heating and firing the container in a sealed state. A method for firing a ceramic molded article containing a high vapor pressure oxide, wherein a firing step is carried out with a molded article for atmosphere control made of a high vapor pressure oxide or a material containing the high vapor pressure oxide. 2. The method for firing a ceramic compact containing a high vapor pressure oxide according to claim 1, wherein the atmosphere controlling compact is a sheet-like compact and is laid in the container. A high-melting-point oxide sheet is placed on the sheet-like atmosphere control molded body, and a ceramic molded body for the product is placed on the sheet and fired. A method for firing a ceramic compact containing a vapor pressure oxide.