JPS6060971A - Manufacture of ceramic sintered body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a ceramic sintered body.

The particle size distribution of the ceramic main raw material usually varies from milling lot to milling lot. As a result, ceramic sintered bodies manufactured using lots of ceramic main raw materials with different particle size distributions often have different firing shrinkage rates. The firing shrinkage rate will not be a problem if the lots have similar particle size distributions, but if the particle size distributions are different, the firing shrinkage rate will be ±0.3%.
This often changes. At manufacturing sites, ceramic sintered bodies are generally cast, pressed, or extruded.

It is manufactured by molding by a method such as tape keyasting and then firing, but in either method, the variation in the firing shrinkage rate of the ceramic sintered body directly determines the dimensional accuracy of the product. Particularly in recent years, the demand for dimensional accuracy has become more and more important for substrates for electronic components, and the industry is now aware that the firing shrinkage rate of the ceramic sintered body, which is punched and formed using a metal mold and then sintered, differs depending on the raw material lot. has become a major bottleneck.

Conventionally, such fluctuations in the firing shrinkage rate of Senmic sintered bodies have been dealt with using the method described below.

(1) From a large amount of sintered bodies, only those sintered bodies that meet the customer's required dimensions are selected as products.

(2) Correct the dimensions by post-processing.

(3) Measure the firing shrinkage rate of the original product when removing light as the raw material lot changes, and redesign the mold for manufacturing the sintered body.

(4) After measuring the firing shrinkage rate of the original product as described above,
The firing shrinkage rate is adjusted by changing the blending ratio of the raw material powder or by adding other ingredients.

However, method (1) results in an extremely low yield and increases the number of days required for manufacturing, while method (4), which is common, increases porosity after sintering and reduces surface smoothness. etc. occur.

The object of the present invention is to provide a method for producing a ceramic sintered body that does not have the above-mentioned drawbacks.

The present inventors focused on the fact that the firing shrinkage rate increases as the specific surface area increases even if the sintering aid in the ceramic sintered body has the same average particle size, and as a result of various studies, we found that the particle size distribution of the ceramic main raw material By mixing two or more types of sintering aids having substantially the same average particle size and different specific surface area even though the particles have different sizes, it was confirmed that the firing shrinkage rate could be controlled arbitrarily.

The present invention relates to a method for producing a ceramic sintered body, in which a main raw material powder is mixed with a combination of two or more sintering aids having approximately the same average particle diameter and different specific surface areas, and then molded and fired.

The ceramic sintered body of the present invention uses ceramic as the main raw material, to which sintering aids, binders, solvents, etc. are added, and if necessary, phthalate esters of DOP and DBP, triethylene glycol, A plasticizer such as polyalkylene glycol is added.

In the present invention, the main ceramic raw material is alumina.

Zirconia etc. are used, and silica is used as a sintering aid.

Glass frit made of magnesia, calcia, alumina, etc. is used. The binder used is polyvinyl butyral, acrylic resin, vinyl acetate copolymer, polyvinyl alcohol, vinyl chloride, methacrylate, etc., and the solvent used is trichlorethylene, phthanol, or ethyl alcohol.

Methyl alcohol etc. can be used.

There are no particular restrictions on the method of obtaining sintering aids with different specific surface areas; for example, the same ball mill may be used to change the blending amount and pulverized for the same time, or ball mills with different radii may be used so that the average particle diameters are equal to each other. Pulverize to change specific surface area. In particular, when the specific surface area is to be made very small, it may be pulverized using a jet mill equipped with a classifier or the like.

It is essential that the average particle size of the sintering aid used in the present invention is almost the same; if it differs greatly, the powder filling state in the ceramic sintered body will change and the characteristics of the ceramic sintered body will deteriorate. . Note that the term "almost the same" preferably means that the tolerance is ±0.3 μm, and more preferably ±0.2 μm.

The present invention will be explained below with reference to Examples.

The average particle size is 1.1μm for lot 1 and 0.9μm for lot 2.
m and lot 3 are 30 pieces of alumina 9 of 1.3 μm.
6 parts by weight of silica, which had been ground in advance to the particle size and specific surface area shown in Table 1, as a sintering aid.

4 parts by weight of 6 types of glass frits consisting of magnesia, calcia, and alumina, 6 parts by weight of polyvinyl butyral as a binder, and 3 parts by weight of phthalate ester as a plasticizer.
54 parts by weight and 45 parts by weight of an azeotrope of trichlorethylene and methanol as a solvent were added respectively.
A ceramic slurry was obtained by mixing for a period of time, and then a ceramic green sheet with a thickness of 0.95 tran was obtained by tape casting. Next, the ceramic green sheet was punched out with a mold to a size of 48.3 x 45.93, and then fired in air at a temperature of 15607:' to produce ceramic firing.
Obtained the original product. The firing shrinkage rates at that time are shown in Table 1 and Figure 1. As a result, the alumina of Lot 1 had a flatness of 3.
By using this sintering aid, it was possible to obtain a ceramic sintered body with a firing shrinkage rate of 16.0% as indicated by the dotted line in FIG. 1. However, for the aluminas of Lots 2 and 3, no matter which sintering aid was used, the firing shrinkage rate was 16.
Since it is not possible to obtain a 0% ceramic sintered body, a combination of 50% of the sintering aid of Nii 2 and 50% of the sintering aid of Nii 3 was added to the alumina of Lot 2.
By mixing, it was possible to obtain a ceramic sintered body with a mold firing shrinkage rate of 16.0%. Similarly lot 3
For alumina of 30% and 55% of sintering aid
By adding and mixing 70% of the sintering aid, it was possible to obtain a ceramic sintered body with a firing shrinkage rate of 16.0% set for the P mold.

Table 2 shows the characteristics of the ceramic sintered bodies obtained using each lot of alumina and having a mold setting firing shrinkage rate of 16%.

The following margins indicate that the invention is based on the main raw material powder, which has approximately the same average particle size but is comparatively different.
By combining more than one type of sintering aid, mixing, molding, and then firing, we can improve the yield and produce ceramic sintered bodies with high precision and a low shrinkage rate in a short period of time. can.

[Brief explanation of the drawing]

Figure 1 shows the relationship between specific surface area and firing shrinkage rate for alumina lots 1 to 3 using six types of sintering aids with seven different surface areas.

Claims (1)

[Claims] 1. A method for producing a ceramic sintered body, which comprises mixing a main raw material powder with a combination of two or more sintering aids having approximately the same average particle size and different specific surface areas, shaping and firing the mixture.