JPH0245107A - Manufacture of ceramic green sheet and casting apparatus - Google Patents

Abstract

PURPOSE:To make the contraction stress generated by drying escape to the end part, and form a ceramic green sheet in a high yield by making the evaporation rate of solvent in the central part of a strip-form green sheet faster than that of the end, and drying the central part earlier than the end part. CONSTITUTION:A first drying box part is provided with air blowers 71-73 blowing dried air 9, and exhaust blowers 81-83 exhausting the air containing solvent evaporated corresponding respectively to them. The blowing ports 14 of the air blower 71-73 and the suction ports 15 of the exhaust blowers 81, 82, 83 are divided respectively into many parts in the width direction of strip form slurry, and besides constituted such that the air-flow speed can be controlled by each blowing ports. In this fashion, the air-flow speed around the B point is controlled to be greater than that around A point and C point. Consequently, setting the difference of air-flow speed to be +0.1m/s or more, the cracking generating rate of a green sheet becomes low considerably.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a ceramic green sheet manufacturing method for manufacturing green sheets from slurry and a casting device for the same, and particularly relates to ceramic green sheets used for multilayer wiring boards, etc. The present invention relates to a sheet manufacturing method and a casting device for performing the same.

[Conventional technology]

Figure 2 (,) shows a perspective view of a conventional casting device for manufacturing ceramic green sheets by the doctor blade method. Mixed slurry 2 is poured onto the biner sheet 3, and when the belt 1 is moved in the direction of the arrow, Accordingly, the biner sheet 3 moves from left to right in the figure. Mixed slurry 2 includes doctor blade 10 and binder sheet 3
It flows out from between the holes to a certain thickness and enters the drying box 4. The drying box 4 is divided into three drying box parts, and the first drying box part 41 has a blower 7 for blowing air 9 and a blower for exhaust, as shown in FIG. 2(b) in cross section. It has an exhaust blower 8. Here, the mixed slurry 2 is dried at a predetermined temperature, and then further dried in a second drying box section 42 and a third drying box section 43 to form a green sheet 6. The temperature of the drying box section is 1st, 2nd, . It is also possible to raise it sequentially to the third. In addition, as related to this type of device, Japanese Patent Application Laid-Open No. 57-
There is 852872.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not give consideration to manufacturing a ceramic substrate with more accurate dimensional accuracy, and there is a problem in that it is difficult to obtain such a ceramic substrate. That is, when producing a green sheet from a mixed slurry by the doctor blade method, the mixed slurry contains a binder and a plasticizer. The larger the amount of these, the more deformation occurs during drilling, hole filling, and pattern printing in the green sheet state, resulting in poor registration, and the greater the shrinkage during sheet firing, making it difficult to obtain accurate dimensional accuracy.

Therefore, it is desirable that the amount of binder etc. be small. However, as the amount of binder etc. is reduced, the viscosity of the green sheet decreases.

When creating green sheets from mixed slurry, there was a problem in that cracks were likely to occur, making it difficult to create green sheets.

This state is shown in FIG. 2(c). Since the evaporation rate of the solvent near the ends A and C of the slurry that progresses in a band shape is higher than that near the center B, drying near the center is delayed, and the green sheet 6 in a dry state and the green sheet 6 in an undried state are separated. The boundary 1 with slurry 2 appears in the shape shown in the figure. Since the green sheet 6 dries from the edges in this manner, stress that tends to shrink due to drying is accumulated near the center line 13, and a crack 12 occurs in the center. Furthermore, if the mixed slurry is rapidly dried, cracks 12 as shown in FIG. 2(d) will occur at the ends.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a ceramic green sheet for manufacturing a ceramic substrate with higher dimensional accuracy, and a casting apparatus for performing the same.

[Means to solve the problem]

The above purpose is as follows: (1) A method for manufacturing a ceramic green sheet in which slurry is flowed out by a doctor blade method and a ceramic green sheet is created by drying the slurry by air blowing, in which the air blowing is carried out along a line perpendicular to the moving direction of the slurry. (2) A method for producing a ceramic green sheet, characterized in that the central part of the slurry is dried before the end parts by varying the wind speed or the air volume, or both, at the central part and the end parts of the slurry. In a casting apparatus for producing ceramic green sheets, the casting apparatus includes at least means for moving the slurry, means for making the slurry a predetermined thickness, and an air blowing means for drying the slurry. This is achieved by a casting device characterized in that it is configured to control the wind speed or air volume, or both, in order to dry the center portion in a line perpendicular to the direction of movement before the end portions.

The air blowing in the present invention is controlled so that the central portion of the band-shaped slurry dries earlier than the end portions.

The blowing air may be dry air or heated dry air.

(Function) The evaporation rate of the solvent in the center of the strip-shaped green sheet is made faster than that at the edges, and the center dries before the edges.Thereby, shrinkage stress due to drying is released to the edges, so no cracks occur. .

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
Figure 1(a) is a longitudinal sectional view of the first drying box part of a casting device according to an embodiment of the present invention, Figure 1(b) is a plan sectional view thereof, and Figure 1(c) is a perspective view of a green sheet. be. The first drying box part includes a blower 71, 72, 73 for blowing dry air 9, and corresponding exhaust blowers 81, 8 for exhausting air containing evaporated solvent.
2,83 are provided. Air blower 71, 72,
The air outlet 14 of 73 and the suction ports 15 of exhaust blowers 81, 82, and 83 are each divided into a plurality of parts in the width direction of the belt-shaped slurry, and are configured so that the wind speed can be adjusted for each air outlet.

As a result, the wind speed near point B (center) shown in FIG. 1(b) is adjusted to be higher than near point A and zero point (edge).

FIG. 4 shows the results of examining the incidence of cracking in green sheets by using this device and varying the wind speed difference between point B and point A (or point 0). The wind speeds at point A and point 0 are set to be the same. The horizontal axis in FIG. 4 is the value obtained by subtracting the wind speed at point A (or point 0) from the wind speed at point B, and a positive value indicates that the wind speed at point B is high. As shown in the figure, if the above-mentioned wind speed difference is set to 10.1 m/s or more, the incidence of cracking in the green sheet becomes extremely low.

Furthermore, the rate of occurrence of cracking in the green sheet also changes depending on the wind speed at the central point B. The relationship is shown in FIG. Too rapid drying increases the chance of cracking. Furthermore, Figure 5 shows the wind speed at point B in Figure 1(b).

That is, it relates to the wind speed at which the slurry is initially dried. If the slurry is dried to some extent at this point, it may be dried under stronger conditions as the slurry progresses.

For example, the wind speed at a point between blower 71 and exhaust blower 81 is 0.5+a/s, the wind speed at a point between blower 72 and exhaust blower 82 is 0.9 m/s, and blower 7
Even if the wind speed at the point between No. 3 and the exhaust blower 83 is 1.5 m/s, almost no cracking occurs. The above wind speeds are the wind speeds at the center, and the difference in wind speed between the center and the ends was +0.1 m/s.

FIG. 3 is a side sectional view of the first drying box section for explaining another embodiment of the present invention. Figure 1 (a) and (
Air blower air outlet 14 and exhaust blower shown in b)
Instead of dividing the suction ports 15, arch-shaped shielding plates 16 shown in FIG. 3 are provided between the ventilation blowers 71, 72, 73 and the exhaust blowers 81, 82, 83, respectively. Therefore, it is possible to change the wind speed and volume near the center of the belt-shaped slurry and those near the ends.

〔Effect of the invention〕

According to the present invention, a ceramic green sheet for manufacturing a ceramic substrate having more accurate dimensional accuracy could be manufactured at a high yield.

[Brief explanation of the drawing]

FIG. 1(a) is a longitudinal sectional view of the first drying box part of a casting device according to an embodiment of the present invention, FIG. 1(b) is a plan sectional view thereof, and FIG. 1(c) is a perspective view of a green sheet. figure,
Fig. 2(,) is a perspective view of a conventional casting device, Fig. 2(b) is a vertical sectional view of its first drying box section,
Figure (Q) and Figure 2 (d) are perspective views of the green sheet;
FIG. 3 is a side sectional view of the first drying box section of another embodiment of the present invention, and FIGS. 4 and 5 are diagrams for explaining the present invention. 1...Belt 2...Slurry 3...
・Viner sheet 4...Drying box 5...Roller 6...Green sheet 7.71.7
2.73...Air blower-8, 81, 82, 83...
- Exhaust blower 9... Air 11... Boundary 13... Center line 15... Suction port 41... First drying box section 42... Second drying box section 43,... 3 Drying box section

Claims (2)

[Claims] 1. In a ceramic green sheet production method in which a ceramic green sheet is created by flowing out slurry using a doctor blade method and drying the slurry by air blowing, the air blowing is performed in a direction perpendicular to the direction of movement of the slurry. A method for producing a ceramic green sheet, characterized in that the central part of the slurry is dried before the end parts by varying the wind speed, the air volume, or both. 2. It has at least a means for moving the slurry, a means for making the slurry a predetermined thickness, and an air blowing means for drying the slurry. In the casting device for manufacturing ceramic green sheets, the blowing means is configured to control the wind speed, the air volume, or both in order to dry the central part in a line perpendicular to the moving direction of the slurry before the end parts. A casting device characterized by: