JPH01310903A - Manufacture of green sheet for ceramic multilayer board - 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 Field of Industrial Application The present invention relates to a method for manufacturing a green sheet for a ceramic multilayer substrate.

Conventional technology To explain the conventional method of applying ceramic multilayer substrates, first, ceramic powder and organic components such as a solvent, a dispersant, a binder, and a plasticizer are mixed and pulverized using a ball mill to create a slurry. do. Next, foreign substances mixed in this slurry are removed by filtering using a mesh filter or the like.

Subsequently, the slurry is placed in a pot, and the air bubbles contained in the slurry are released under reduced pressure. The clean slurry thus obtained is shaped into a sheet using a doctor blade method or the like and dried to produce a green sheet. Guiaholes of different patterns are formed on the plurality of green sheets thus produced, and conductor layers of different patterns are printed and dried. Next, a desired number of green sheets with different patterns are stacked together, pressed at appropriate temperature and pressure, and fired. Thereafter, a multilayer substrate can be manufactured by forming a thick film on the top layer.

Problems to be Solved by the Invention However, in the conventional manufacturing method described above, even if the air bubbles contained in the slurry are expelled, the air bubbles contained in the deep layer of the slurry IJ- are removed because the slurry is a highly viscous suspension. could not be released sufficiently, and the air bubbles appeared as holes during green sheet molding, and when these were used as an insulating layer, there was a problem of causing a short between the eyebrows. To prevent this, if the pressure is reduced to a level higher than the vapor pressure of the solvent in an attempt to release the air bubbles contained in the deep layer of the slurry, the solvent will rapidly evaporate, the viscosity of the slurry will increase, the sheet formability will deteriorate, and the sheet Issues with cranks, etc. occur.

The present invention solves these conventional problems, and can reduce pinholes in green sheets by releasing air bubbles contained in the deep layer of slurry, and can also suppress the increase in viscosity of slurry. An object of the present invention is to provide a method for manufacturing a green sheet for a ceramic multilayer substrate, which can improve sheet formability.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a step in which a slurry for producing a green sheet is placed in a container with an open top, and air bubbles contained in the slurry are released under reduced pressure.
The pressure is set to the vapor pressure of the solvent, which is a low boiling point component, and the test is carried out while horizontal vibrations are applied to the container.

action The present invention has the following effects due to the above configuration.

That is, when the air bubbles contained in the slurry are released under reduced pressure, the pressure is set to the vapor pressure of the solvent, so that the solvent present in the surface layer of the slurry is slowly vaporized, and the air bubbles are also released at the same time.

At this time, the vapor pressure of the solvent is lowered by other mixtures, so even if the pressure is lowered to the vapor pressure of the solvent alone, the solvent will not reach its boiling point and intense vaporization will not occur. It is also possible to suppress the increase to a very small amount. Furthermore, by releasing air bubbles while applying horizontal vibration to the container, the deep layer of the slurry can be pulled up to the surface layer along the side wall of the container, and the contained air bubbles can be released as the solvent in that area is vaporized.

Example Examples of the present invention will be described below.

For 100 parts by weight of ceramic powder obtained by mixing 50 wt% of Al2O3 and 5iOzB203, 50 parts by weight of methyl ethyl ketone as a solvent, 2 parts by weight of polyethylene glycol as a dispersant, 10 parts by weight of polyvinyl butyral as a binder, and 2 parts by weight of polyvinyl butyral as a plasticizer. 4 parts by weight of benzyl phthalate was added, and the mixture was mixed and pulverized using a ball mill for 48 hours to prepare a slurry. This slurry was filtered through a #120 mesh filter to remove foreign matter, and then air bubbles contained in the slurry were released using a defoaming device shown in FIG. In this defoaming device, a chamber 2 is provided on a horizontal vibration device 1, a vacuum pump 4 is connected to the chamber 2 via a pulp 3, and a leak pulp 5 is provided. In the chamber 2, a polyethylene pot 7 containing the slurry 6 and having an open top is placed on the vibrating device 1. This defoaming device drives the vacuum pump 4, reduces the pressure inside the chamber 2 to a predetermined pressure by adjusting the pulp 3.5, and also vibrates the pot 7 in the horizontal direction using the horizontal vibration device 1. can. In this example, 1000 m/ of the slurry 6 was put into a pot (2000 g capacity) 7, and the slurry was heated at a room temperature of 20C and a pressure cuff of 1.2 mmHg.
The pot 7 was shaken by the horizontal vibration device 1 for 0 minutes as shown in Fig. 2 (
As shown in a) to (d), the deep layer 6a of the slurry 6 was pulled up to the surface layer along the side wall of the pot 7 by reciprocating in the horizontal direction at 1100 ff1 per second, and air bubbles were released from the slurry 6. As a comparative example, slurry 6 1000
Put d into pot (2000rul capacity) 7,
Bubbles were released from slurry 6 at room temperature (°C) under the following conditions.

Comparative Example 1 The sample was left for 10 minutes without vibration under a pressure of 200 mm) (g).

Comparative Example 2 10 without vibration under pressure 1100WIK)
Leave it for a minute.

Comparative Example 3 The cuff was left for 10 minutes without vibration under a pressure cuff of 1.2 Hg (vapor pressure of MEK at 20°C).

Comparative Example 4 The sample was left for 10 minutes under a pressure of 20 Hg without vibration.

Using the slurries of the above-mentioned examples of the present invention and comparative examples 1 to 4, the slurry was coated on a polyester film with a width of 1 by the doctor blade method.
Green sheets with a thickness of 50 mm and a thickness of approximately 250 μm were prepared, each green sheet was canted into a 150 mm opening, the presence or absence of pinholes was examined, the occurrence rate was calculated, and the crank occurrence rate was calculated.
As shown in the table.

Margin below As is clear from Table 1 above, in Comparative Examples 1 to 4,
In the region where the degassing pressure is higher than the vapor pressure of the solvent, the pinhole occurrence rate decreases as the pressure decreases, but it is not sufficient.
In the pressure region below the vapor pressure of the solvent, the viscosity of the slurry increased due to excessive vaporization of the solvent, so the liquid movement during sheet forming was not smooth and binhonopekranok occurred.

On the other hand, green sheets made from slurry that has been degassed by applying horizontal vibration under the vapor pressure of a solvent, as in the example of the present invention, do not generate cracks and are significantly less prone to pinholes. has declined to

Effects of the Invention As described above, according to the present invention, when the slurry is placed in a container with an open top and the air bubbles contained in the slurry are released under reduced pressure, the pressure is set to the vapor pressure of the solvent. By slowly vaporizing the solvent present in the surface layer of the slurry, bubbles are simultaneously released. At this time, the vapor pressure of the solvent is lowered by other mixtures, so even if the pressure is lowered to the vapor pressure of the solvent alone, the solvent will not reach its boiling point and intense vaporization will not occur, so the slurry viscosity due to excessive vaporization of the solvent It is possible to suppress the rise in Furthermore, by releasing air bubbles while applying horizontal vibration to the container, the deep layer of the slurry can be pulled up to the surface layer along the side wall of the container, and the contained air bubbles can be released as the solvent in that area is vaporized.

Therefore, the moldability of the green sheet can be improved, and pinholes in the green sheet can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a defoaming device used in the green sheet manufacturing method of the present invention, and FIG. 2 (a) to (d) are explanatory diagrams of its operation. 1... Horizontal vibration device, 2... Chamber, 3...
...Pulp, 4...Vacuum pump, 5...Leak valve, 6...Slurry, 6a...Deep part of slurry, 7
···pot.

Claims (1)

[Claims] The slurry for producing green sheets is placed in a container with an open top, and when the air bubbles contained in this slurry are released under reduced pressure, the pressure is set to the vapor pressure of the solvent, which is a low boiling point component, and the container is placed in a horizontal direction. A method for manufacturing a green sheet for a ceramic multilayer substrate, characterized in that the manufacturing method is performed while applying vibrations.