JPH0218589B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method for manufacturing a ceramic substrate, and more particularly to an improvement in means for forming a so-called green sheet on an unfired ceramic substrate.

(2) Background of the Invention Ceramic materials mainly composed of alumina (Al ₂ O ₃ ) are used in the field of electronic equipment, for example, as insulating substrate materials for mounting electronic components, insulating substrate materials for hybrid integrated circuits, and container materials for housing semiconductor elements. It is applied to etc.

In the field of electronic devices, semiconductor integrated circuit elements are becoming more highly integrated, and conductor layer patterns formed on the surface of the insulating substrate or container are being made finer and more highly integrated.

For this reason, the ceramic substrate constituting the insulating substrate or container is also required to have particularly high surface smoothness.

(3) Prior art and problems Conventionally, the ceramic substrate is produced by forming a pre-sintered ceramic substrate (green sheet) by the so-called doctor blade method, forming a conductive layer pattern on the surface of the green sheet as necessary, Further, if necessary, a plurality of such green sheets are laminated, and then the green sheets are heated and pressed to sinter.

Here, the doctor blade method conventionally has a structure shown in FIG. 1, for example.

In the figure, 11 is a ceramic slurry 12
13 is a doctor blade provided on one side of the slurry reservoir, 14 is a slurry supply pipe, and 15 is a slurry level gauge. The ceramic slurry 12 contained in the slurry reservoir 11 is applied onto the surface of a carrier film 17 which is disposed below the slurry reservoir 11 and is moved by a carrier belt 16.
As it moves, it flows out from the doctor blade 13 portion, and a slurry film or layer 18 is formed on the surface of the carrier film 17. A ceramic green sheet is then formed by drying the slurry film or layer 18.

However, when forming a green sheet by such a doctor blade method, the slurry film or layer 1 formed on the carrier film 17 is
No. 8 shrinks during drying, resulting in a phenomenon in which both ends are thicker than the center, especially in the thickness distribution in the width direction. This state is the second
As shown in the figure. In the figure, 21 is a green sheet;
22 is the thick part.

The occurrence of such thick portions 22 results in a decrease in the effective width of the green sheet, which is one of the causes of an increase in the price of ceramic substrates using such green sheets.

(4) Purpose of the Invention The present invention involves forming a ceramic slurry film or layer by flowing a ceramic slurry contained in a slurry reservoir onto a carrier film using a doctor blade method, and then drying the slurry film or layer. An object of the present invention is to provide a manufacturing method that can form a green sheet with a uniform thickness when forming the green sheet.

(5) Structure of the Invention Therefore, according to the present invention, a ceramic slurry contained in a slurry reservoir is formed into a film or a layer on a carrier film by a doctor blade method, and then the ceramic slurry film or layer is dried. In the method for manufacturing a ceramic substrate, which includes a step of forming an unfired ceramic substrate, the doctor blade is provided with protrusions substantially perpendicular to the surface of the carrier film at both ends in the width direction. Ru.

(6) Embodiments of the Invention The present invention utilizes the viscosity of the ceramic slurry to eliminate uneven thickness caused by drying and shrinkage of the ceramic slurry formed into a film or layer. By selectively changing the shape of the tip of the doctor blade, the thickness of the ceramic slurry in areas where the thickness becomes uneven due to shrinkage can be corrected by looking at the thickness after drying. This makes the thickness uniform and increases the effective width of the green sheet.

The present invention will be explained in detail below using examples.

According to the present invention, as shown in FIG. 3, for example, protrusions 32A and 32B facing downward (in the direction of the carrier film) are provided at both ends of the ceramic slurry outflow portion 31A of the doctor blade 31. Due to the presence of the protrusions 32A and 32B, the amount (thickness) of the ceramic slurry flowing out from below the doctor blade 31 is smaller (thinner) at both ends of the doctor blade 31 than at the center.

Therefore, when the ceramic slurry film or layer formed on the carrier film using such a doctor blade is dried to form a green sheet, the protruding height of the thick part that occurs at both ends in the width direction. is an extremely small value. The effective width of such green sheets is therefore significantly increased.

For example, if the width W ₁ of the doctor blade 31 shown in FIG.
The height H ₁ of 2B is 0.05 [mm], the width W ₂ is 20 [mm], the main component is alumina (Al ₂ O ₃ ), the viscosity is 5000 to 10000 pcs, and the specific gravity is polyvinyl butyrate, alcohol, and ketones. Ceramic slurry film (sheet) using ceramic slurry of 1.7~1.8
When this was dried to form a green sheet with a thickness of 0.7 [mm], the length of the flat part in the width direction of the green sheet reached 180 [mm], and the protrusion that occurred on the outside of the flat part The protrusion height of the part is 0.05
It was [mm].

On the other hand, according to the conventional method, a ceramic slurry film (sheet) was formed using a 200 mm wide doctor blade without protrusions at both ends.
When such a ceramic slurry film is dried, the effective width of the flat part of the formed green sheet remains at 150 [mm], and a protruding part with a protruding height of 0.1 [mm] is formed outside the flat part. will occur.

That is, according to the present invention, by arranging the protrusions at both ends of the doctor blade, the flatness of the green sheet in the width direction can be improved,
The effective width of the green sheet can be significantly increased (by 20% in the above example).

Incidentally, the protrusions arranged at both ends of the doctor blade according to the present invention are thick parts that are formed at both ends of the green sheet after drying, regardless of the width of the doctor blade, that is, the width of the green sheet to be formed. have almost the same shape, so the height
It is practically preferable that H ₁ is 0.02 to 0.10 [mm] and the width is 10 to 30 [mm]. At this time, if the viscosity of the ceramic slurry is high even if the drying shrinkage rate is the same, the height H ₁ of the protruding part of the doctor blade may be small, and if the drying shrinkage rate is small even if the viscosity is the same, the height H ₁ of the protruding part is should be small.

Further, the shape of the protrusions disposed at both ends of the doctor blade is not limited to the shape shown in FIG. 3, but may also be shaped as shown in FIG. 4, for example.

In the configuration shown in FIG. 4a, protrusions 42A provided at both ends of the doctor blade 41,
42B is provided with intermediate protrusions 42a and 42b to form a stepped shape. According to such a structure of the protrusion, the amount of the ceramic slurry at both ends in the width direction of the ceramic slurry film or layer formed on the carrier film is limited, and the amount of the ceramic slurry at both ends in the width direction when dried to form a green sheet is limited. The protrusion height can be further reduced.

Further, in the configuration shown in FIG. 4b, the inner edges of the protrusions 42A and 42B provided at both ends of the doctor blade 41 are sloped surfaces.

Further, in the configuration shown in FIG. 4c, the inner edges of the protrusions 42A and 42B provided at both ends of the doctor blade 41 are curved inclined surfaces.

Even with such a shape of the protrusion, the object of the present invention can be achieved.

(7) Effects of the Invention As described above, according to the present invention, when forming a ceramic green sheet by the doctor blade method, both ends in the width direction of the ceramic slurry film or layer formed on the carrier film The amount of the ceramic slurry can be suppressed. Therefore, when drying the ceramic slurry to form a ceramic green sheet, it is possible to suppress the protrusion height of the protrusions that occur at both ends of the ceramic green sheet in the width direction, and to reduce the effective width of the ceramic green sheet. can be expanded significantly.

[Brief explanation of drawings]

FIG. 1 is a side sectional view a and a front view b showing the configuration of a conventional doctor blade method. FIG. 2 is a sectional view showing the state of a ceramic green sheet formed by such a doctor blade method. FIG. 3 is a front view showing the structure of the doctor blade according to the present invention, and FIGS. 4a to 4c are front views showing other structures of the doctor blade according to the invention. In the figure, 11...slurry reservoir, 12...
Ceramic slurry, 13, 31, 41...Doctor blade, 32, 42...Protrusion provided on doctor blade.

Claims (1)

[Claims] 1. Production of a ceramic substrate comprising the steps of forming a ceramic slurry contained in a slurry reservoir into a film or layer on a carrier film by a doctor blade method, and then drying the ceramic slurry film or layer to form an unfired ceramic substrate. A method for manufacturing a ceramic substrate, characterized in that the doctor blade is provided with protrusions substantially perpendicular to the carrier film surface at both ends in the width direction.