JP3287274B2 - Manufacturing method of ceramic green sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a ceramic green sheet, and more particularly to a method for manufacturing a ceramic green sheet while being backed by a carrier film.

[0002]

2. Description of the Related Art For example, when manufacturing a multilayer ceramic electronic component such as a multilayer ceramic capacitor, ceramic green sheets are laminated. However, the performance of the multilayer ceramic electronic component is improved while reducing the size or thickness. In order to achieve this, it is effective to make the ceramic green sheet thinner.

On the other hand, ceramic green sheets are mechanically weak. Therefore, when thinned as described above, in order to supplement its mechanical strength, a flexible carrier film is prepared, and a ceramic green sheet is formed on the carrier film.
As described above, the ceramic green sheet is also handled in some subsequent steps while being backed by the carrier film.

Conventionally, as described above, in order to form a ceramic green sheet on a carrier film, (1) a doctor blade method, (2) a microgravure roll method,
(3) A reverse roll method or the like is used.

[0005]

However, any of the above-mentioned methods (1) to (3) has a problem to be solved. The method (1) is advantageous in that it requires only relatively inexpensive equipment with a relatively simple structure. However, the thickness of the obtained ceramic green sheet is relatively large, and the air intake and the pinning are not good. Holes and the like are also likely to occur. Therefore, it is difficult to obtain a ceramic green sheet having a thickness of, for example, 10 μm or less with sufficient quality.

In the method (2), for example, a ceramic green sheet having a thickness of 10 μm or less can be formed, but air is easily entrained in a gravure roll rotating at a high speed, and the gravure roll is bent. It is difficult to form a wide ceramic green sheet. In the method (3), as in the method (1), the thickness of the obtained ceramic green sheet varies greatly.
And pinholes are also likely to occur. Therefore, for example, 1
It is practically difficult to apply the ceramic green sheet having a thickness of 0 μm or less to molding. In addition, since a strong shearing force acts on the ceramic slurry in the reverse rotation part of each roll,
Depending on the state of the ceramic slurry, the quality of the obtained ceramic green sheet tends to change, and air is likely to be entrained in the reverse rotation portion. Therefore, it is difficult to increase the molding speed.

In each of the methods (1) to (3), the ceramic slurry is supplied directly to the portion where the ceramic slurry is applied to the carrier film. For example, when pulsation occurs, there is also a problem that the pulsation directly affects the quality of the ceramic green sheet. Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a method for producing a ceramic green sheet capable of producing a ceramic green sheet having a thickness of, for example, 10 μm or less, more preferably 5 μm or less at high speed and with high quality. It is to be.

[0008]

In order to solve the above-mentioned technical problems, a method for manufacturing a ceramic green sheet according to the present invention includes a first slurry chamber for receiving a ceramic slurry to be pumped, and a first slurry chamber. A slurry flow passage communicating with the first slurry chamber and having a narrower cross section than the first slurry chamber;
A second slurry chamber communicating with the slurry flow path and having a cross section wider than the slurry flow path and having an opening facing the outside, wherein a doctor edge is formed along one side edge of the opening; Are prepared,
A carrier film for forming a ceramic green sheet made of ceramic slurry thereon is prepared. Then, the ceramic slurry fed to the first slurry chamber is supplied to the second slurry chamber through the slurry flow path, and the carrier film is pressed against the peripheral edge of the opening of the second slurry chamber so as to be pressed. Is closed, and in this state, a ceramic green sheet made of ceramic slurry is formed on the carrier film by moving the carrier film along the opening in a direction in which the doctor edge is on the downstream side.

In the method for manufacturing a ceramic green sheet according to the present invention, the ceramic slurry fed into the first slurry chamber removes agglomerated particles having an average particle size of 10 times or more the average particle size of the ceramic powder contained in the ceramic slurry in advance. It is preferable that they are obtained. The method for producing a ceramic green sheet according to the present invention is advantageously applied when the thickness of the ceramic green sheet formed on the carrier film is 10 μm or less.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to carry out the method for manufacturing a ceramic green sheet according to the present invention as described above, the manufacturing apparatuses shown in FIGS. 1 to 6 can be used. These manufacturing apparatuses are commonly provided with a first slurry chamber for receiving a ceramic slurry to be pumped, a slurry flow path communicating with the first slurry chamber and having a smaller cross section than the first slurry chamber, A second slurry chamber having a cross section wider than the slurry flow path and having an opening facing the outside, wherein a doctor edge is formed along one side edge of the opening, and a first slurry chamber is formed in the first slurry chamber. A slurry coater adapted to supply the pumped ceramic slurry through a slurry flow path to a second slurry chamber. Further, these manufacturing apparatuses close the opening by pressing a carrier film for forming a ceramic green sheet made of ceramic slurry thereon onto the peripheral portion of the opening of the second slurry chamber, and the doctor edge is downstream. A carrier film holding member for holding the carrier film is provided so as to move the carrier film in a direction toward the side.

FIG. 1 is a view for explaining a method of manufacturing a ceramic green sheet according to an embodiment of the present invention. FIG. 1 is a cross-sectional view of a first example of a manufacturing apparatus in a state where a ceramic green sheet is manufactured. This is shown schematically in the figure. As shown in FIG. 1, a manufacturing apparatus 1 applies a ceramic slurry 2 onto a carrier film 3, thereby forming a ceramic green sheet 4 on the carrier film 3. And a backing roll 6 as a holding member.

The slurry coater 5 has a first slurry chamber 8 for receiving the ceramic slurry 2 fed by pressure as indicated by an arrow 7, and a cross section communicating with the first slurry chamber 8 and having a narrower cross section than the first slurry chamber 8. And a second slurry chamber 11 communicating with the slurry flow path 9 and having a cross section wider than the slurry flow path 9 and having an opening 10 facing the outside. A doctor edge 12 is formed along the periphery of the opening 10 and along one side edge thereof.

In the slurry coater 5, the ceramic slurry 2 fed to the first slurry chamber 8 is supplied to the second slurry chamber 11 through the slurry flow path 9. As described above, when the ceramic slurry 2 is supplied from the first slurry chamber 8 to the second slurry chamber 11, the internal pressure of the second slurry chamber 11 is increased by passing through the slurry flow path 9 having a relatively narrow cross section. To be kept high and constant.

The ceramic slurry 2 to be fed into the first slurry chamber 8 is preferably one in which agglomerated particles having an average particle diameter of at least 10 times the average particle size of the ceramic powder contained in the ceramic slurry 2 have been removed in advance. . Therefore, for example, an absolute filtration filter that can reliably collect the aggregated particles having an average particle size of 10 times or more of such a ceramic powder is used, and only the ceramic slurry filtered by this filter is used as the ceramic slurry 2 as the first slurry. Is supplied to the slurry chamber 8.

On the other hand, the backing roll 6 closes the opening 10 by pressing the carrier film 3 against the peripheral edge of the opening 10 of the second slurry chamber 11 while disposing the carrier film 3 on the peripheral surface. It is located in. More specifically, the opening 10 of the second slurry chamber 11 is directed upward, and the carrier film 3 is located on a portion of the backing roll 6 that faces downward.
This opening 10 is closed. Carrier film 3
Is supplied to the peripheral surface of the backing roll 6 via the guide roll 13, and the backing roll 6 is rotated in the direction of the arrow 14, so that the doctor edge 12 is moved in the downstream direction.

In the manufacturing apparatus 1 having such a configuration, the ceramic slurry 2 is fed under pressure to the first slurry chamber 8 and then supplied to the second slurry chamber 11 through the slurry flow path 9. On the other hand, the carrier film 3 arranged on the peripheral surface of the backing roll 6 closes the opening 10 of the second slurry chamber 11 while holding the backing roll 6.
Is moved along the opening 10 of the second slurry chamber 11 according to the rotation of. Thus, when the carrier film 3 passes through the doctor edge 12, the pressure exerted by the doctor edge 12 causes the second slurry chamber 11
The ceramic slurry 2 is applied to the carrier film 3 with a uniform thickness. In this way, the ceramic green sheet 4 made of the ceramic slurry 2 is formed on the carrier film 3.

As described above, according to this embodiment, in the portion where the ceramic slurry 2 is applied to the carrier film 3, the shearing force does not act so much on the ceramic slurry 2, so that it is not affected by the viscosity of the ceramic slurry 2,
Stable molding can be performed. Also, since no air is involved, the molding speed can be increased without any problem.

Further, since the ceramic slurry 2 is applied onto the carrier film 3 in a pressurized state, defects such as pinholes in the obtained ceramic green sheet 4 can be reduced. Further, by forming the doctor edge 12 from, for example, a hard metal or the like, it is possible to eliminate the problem of bending as in a gravure roll. Can be molded.

Further, since the slurry flow path 9 having a relatively narrow cross section is provided between the first slurry chamber 8 and the second slurry chamber 11, the first slurry chamber 11 is provided with the first slurry chamber 9. Of the ceramic slurry 2 to be supplied to the second slurry chamber 8 can be made less susceptible to irregularities such as pulsation of a pump for pumping.
It is easy to keep the internal pressure high and constant.

From these facts, it has been conventionally difficult to mold on a mass production scale.
Even a ceramic green sheet 4 having a thickness of not more than μm can be formed with high quality at a high speed at a wide width. The ceramic green sheet 4
Can be adjusted by changing the interval between the backing roll 6 and the doctor edge 12 or by changing the internal pressure of the second slurry chamber 11. The thickness of the ceramic green sheet 4 can also be adjusted by adjusting the viscosity, specific gravity, concentration, etc. of the ceramic slurry 2 used.

Further, according to the manufacturing apparatus 1 shown in FIG. 1, the backing roll 6 for arranging the carrier film 3 on the peripheral surface thereof is provided. It is possible to stably maintain the state in which the opening 10 is closed by being pressed against the peripheral portion of the opening 10 of the chamber 11, and the carrier film 3 can be moved as desired by the rotation of the backing roll 6.

Hereinafter, an experimental example performed to confirm the effect of the present invention will be described. By weighing a predetermined amount of each of ceramic powder, solvent and organic binder in the range of 0.4 to 0.5 μm in average particle size for the multilayer ceramic capacitor, mixing and dispersing using a medium stirring mill, A ceramic slurry was obtained.

The obtained ceramic slurry was filtered with an absolute filtration filter in order to surely collect agglomerated particles having an average particle diameter of 10 times or more of the ceramic powder contained therein. Ceramic slurry 2 thus prepared
Is supplied to the first slurry chamber 8 of the slurry coater 5 shown in FIG. 1 by a pump, and while the moving speed of the carrier film 3 is kept constant, the backing roll 6 and the doctor edge 12 By adjusting the spacing and the flow rate of the pump, the second slurry chamber 1
The pressure of the ceramic slurry 2 in 1 is 200-600 mm
Aq was set to about Aq, and in that state, the ceramic slurry 2 was applied onto the carrier film 3.

The ceramic slurry 2 thus applied was dried on the carrier film 3 as it was to form a ceramic green sheet 4 having a thickness of 5 μm. On the other hand, as a comparative example, while using the same ceramic slurry, treated by a microgravure roll method,
A ceramic green sheet having a thickness of 5 μm was formed.

The embodiment of the present invention thus obtained
Example ceramic green sheet and comparative example ceramic
For each of the Mick Green sheets, the density (g
/cm ^Three), Thickness variation (%) and 100cm^Two
The number of pinholes with a diameter of 5μm or more in the area of
Measure and use these ceramic green sheets
Of multilayer ceramic capacitors manufactured using
Failure rate (%) and IR (insulation resistance) failure rate
(%) Was measured. Table 1 below shows the results of these measurements.
It is shown.

[0026]

[Table 1]

As can be seen from Table 1, the example is different from the comparative example in that the density, the thickness variation, the number of pinholes, the short-circuit failure rate of the multilayer ceramic capacitor, and the IR Excellent results are shown in all aspects of the defect rate. 2 to 6 schematically show, in cross-sectional views, second to sixth examples of the manufacturing apparatus in a state where the manufacturing of the ceramic green sheet is being performed. The manufacturing apparatus shown in these drawings includes many elements corresponding to the elements provided in the manufacturing apparatus 1 shown in FIG. 1, and therefore, the corresponding reference numerals used in FIG. Thus, duplicate description will be omitted.

In the manufacturing apparatus 21 shown in FIG. 2, the opening 10 of the second slurry chamber 11 is directed to the lower right as shown in the figure, and the carrier film is located on the portion of the peripheral surface of the backing roll 6 which is directed to the upper left. 3, the opening 10 is closed. Further, the doctor edge 12 is connected to the first and second slurry chambers 8 and 11 and the slurry flow path 9.
Are formed separately from the housing member 22 forming a doctor edge member 23 having a substantially fan-shaped cross section with a central angle of about 270 degrees, for example. According to such a configuration, even if the width of the ceramic green sheet 4 to be obtained is wide, substantially no bending occurs at the doctor edge 12 so that the ceramic green sheet 4 can be formed with uniform quality. Can be easily realized by selecting the cross-sectional shape and material of the doctor edge member 23 without being restricted by the housing member 22.

In the manufacturing apparatus 31 shown in FIG. 3, the opening 10 of the second slurry chamber 11 is directed downward, and the opening 10 is formed by the carrier film 3 on the upper part of the peripheral surface of the backing roll 6. 10 is closed. In the manufacturing apparatus 41 shown in FIG. 4, the opening 10 of the second slurry chamber 11 is directed rightward in the figure, and the carrier film 3 is located on the leftward portion of the peripheral surface of the backing roll 6. The opening 10 is closed. Also,
The volume of the second slurry chamber 11 is relatively small.

In the manufacturing apparatus 51 shown in FIG. 5, a backing roll is not used as a carrier film holding member, but two holding rolls 52 and 53 are used instead. The two holding rolls 52 and 53 are arranged so as to be vertically arranged, and by rotating these holding rolls 52 and 53 in the directions of arrows 54 and 55, respectively, the carrier film 3 is held by the holding rolls 52 and 53.
Are moved upwards between.

On the other hand, the opening 10 of the second slurry chamber 11 is directed rightward in the drawing, and the holding rolls 52 and 5
3, the opening 10
Is closed. Also in the manufacturing apparatus 61 shown in FIG. 6, a backing roll is not used as a carrier film holding member, and two holding rolls 62 and 63 are used instead. Two holding rolls 62 and 63
Are arranged side by side, and when the holding rolls 62 and 63 rotate in the directions of arrows 64 and 65, respectively, the carrier film 3 holds the holding rolls 62
And 63 are moved leftward as shown.

On the other hand, the opening 10 of the second slurry chamber 11 faces upward, and the opening 10 is closed by the carrier film 3 between the holding rolls 62 and 63.

[0033]

As described above, according to the method for manufacturing a ceramic green sheet according to the present invention, the first slurry chamber for receiving the ceramic slurry to be fed and the first slurry chamber communicating with the first slurry chamber are provided. A slurry passage having a cross section narrower than the chamber and a second slurry chamber communicating with the slurry passage and having a cross section wider than the slurry flow passage and having an opening facing the outside. A slurry coater having a doctor edge formed therein is used, and the ceramic slurry pressure-fed to the first slurry chamber is supplied to the second slurry chamber through the slurry flow path, and the opening of the second slurry chamber is opened. The opening is closed by pressing the carrier film against the periphery of the carrier, and in this state, the carrier filter is moved in the direction in which the doctor edge is on the downstream side. By moving along the arm in the opening, since it is performed to mold the ceramic green sheet made of ceramic slurry on a carrier film, which achieves the following effects.

First, in the portion where the ceramic slurry is applied to the carrier film, since the shearing force does not act so much on the ceramic slurry, stable molding can be performed without being affected by the viscosity of the ceramic slurry. Also, since no air is involved, the molding speed can be increased without any problem. Also, in order to apply the ceramic slurry on the carrier film in a pressurized state,
In the obtained ceramic green sheet, defects such as pinholes can be reduced.

Further, since a slurry passage having a relatively narrow cross section is provided between the first slurry chamber and the second slurry chamber, the second slurry chamber is provided with the first slurry chamber. It is possible to reduce the influence of irregularities such as pulsation of a pump for pumping the ceramic slurry to be supplied, and it is easy to keep the internal pressure of the second slurry chamber high and constant.

From these facts, it has been conventionally difficult to mold on a mass production scale.
Even thin ceramic green sheets of less than μm can be molded with high quality and at high speed. If this is applied to multilayer ceramic electronic components, stable characteristics and miniaturization can be achieved. it can. In the method for manufacturing a ceramic green sheet according to the present invention, as the ceramic slurry to be pumped into the first slurry chamber, a slurry obtained by previously removing aggregated particles having an average particle diameter of 10 times or more of the ceramic powder contained in the ceramic slurry is used. When used, such agglomerated particles can be prevented from being mixed into the ceramic green sheet and hindering proper formation of the ceramic green sheet, so that it is more advantageous for forming a thinner ceramic green sheet.

[Brief description of the drawings]

FIG. 1 is a view for explaining a method of manufacturing a ceramic green sheet according to an embodiment of the present invention, and schematically shows a first example of a manufacturing apparatus in a state where a ceramic green sheet is being formed. It is sectional drawing.

FIG. 2 is a cross-sectional view schematically illustrating a second example of the manufacturing apparatus in a state where molding of a ceramic green sheet is being performed.

FIG. 3 is a cross-sectional view schematically illustrating a third example of the manufacturing apparatus in a state where molding of a ceramic green sheet is being performed.

FIG. 4 is a cross-sectional view schematically showing a fourth example of a manufacturing apparatus in a state where molding of a ceramic green sheet is being performed.

FIG. 5 is a cross-sectional view schematically illustrating a fifth example of the manufacturing apparatus in a state where molding of a ceramic green sheet is being performed.

FIG. 6 is a cross-sectional view schematically illustrating a sixth example of the manufacturing apparatus in a state where molding of a ceramic green sheet is being performed.

[Explanation of symbols]

1, 21, 31, 41, 51, 61 Ceramic green sheet manufacturing apparatus 2 Ceramic slurry 3 Carrier film 4 Ceramic green sheet 5 Slurry coater 6 Backing roll 8 First slurry chamber 9 Slurry flow path 10 Opening 11 Second slurry Chamber 12 Doctor edge 52, 53, 62, 63 Holding roll

(56) References JP-A-11-77627 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B28B 1/30 101

Claims (3)

(57) [Claims] 1. A first slurry chamber for receiving a ceramic slurry to be pumped, a slurry flow path communicating with the first slurry chamber and having a narrower cross section than the first slurry chamber, and communicating with the slurry flow path. And a second slurry chamber having a cross section wider than the slurry flow path and having an opening facing the outside, a doctor edge being formed along one side edge of the opening, a slurry coater being prepared. A carrier film for forming a ceramic green sheet made of ceramic slurry thereon is prepared, and the ceramic slurry pressure-fed to the first slurry chamber is supplied to the second slurry chamber through the slurry flow path. At the same time, the carrier film is brought into pressure contact with a peripheral portion of the opening of the second slurry chamber, thereby opening the opening. In this state, by moving the carrier film along the opening in a direction in which the doctor edge is on the downstream side, a ceramic green sheet made of the ceramic slurry is formed on the carrier film. A method for producing a ceramic green sheet. 2. The method according to claim 1, wherein the ceramic slurry fed into the first slurry chamber is obtained by removing aggregated particles having an average particle diameter of 10 times or more the average particle diameter of the ceramic powder contained in the ceramic slurry in advance. A method for producing the ceramic green sheet according to the above. 3. The method according to claim 1, wherein the thickness of the ceramic green sheet formed on the carrier film is 10 μm or less.