JPS6332909A - Manufacture of laminated ceramic capacitor - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method that makes it possible to manufacture small-sized, high-capacity multilayer capacitors using thin ceramic green sheets, and particularly relates to ceramic green sheets and internal electrodes. The present invention relates to a manufacturing method in which the process of forming a pattern is improved.

[Prior Art 1 A conventional general method for manufacturing a multilayer ceramic capacitor is as follows.

An internal electrode paste of a predetermined size is applied onto a ceramic green sheet of a predetermined size by, for example, screen printing, so that the internal electrode paste parts to be laminated are arranged alternately in the thickness direction. The ceramic green sheets coated with the internal electrode paste are laminated and pressure bonded to obtain a ceramic laminate. Next, the ceramic laminate is fired and further provided with external electrodes.

[Problems to be Solved by the Invention] However, when the thickness of the sheet is reduced in order to increase the capacity, the strength of the sheet decreases, making it difficult to handle the sheet. For example, when a ceramic green sheet is directly held using a suction chuck, holes may be formed in the sheet due to the suction force.

In addition, when screen printing the internal electrode paste, it is a wet process, so when the thickness of the sheet is reduced in order to increase the capacity, the internal electrode paste penetrates into the sheet, and the ceramic green sheet contains an organic binder. In this case, the binder may be redissolved by the permeated electrode paste, causing the ceramic green sheet to shrink or even locally swell or deform during the drying process after printing.

Furthermore, in screen printing, the printing plate is pressed against the plate using a squeegee, which does not provide sufficient printing accuracy. Therefore, during mass production, it is difficult to disperse and form a large number of internal electrode patterns at accurate pitches.

In addition, thin ceramic green sheets always have pinholes and pores, and when electrode paste is pressed onto the ceramic green sheet with a squeegee, the electrode paste enters into the pinholes and pores, resulting in In multilayer capacitors, this may lead to short-circuit failure or a drop in dielectric breakdown voltage.

Therefore, an object of the present invention is to provide a multilayer capacitor that does not require careful handling even when a thin ceramic green sheet is used to increase the capacitance, and that can eliminate the above-mentioned drawbacks associated with the formation of internal electrodes. The purpose of this invention is to provide a method for manufacturing the same.

[Means for Solving the Problems] The method for manufacturing a multilayer capacitor of the present invention first includes a sheet supply band in which a ceramic green sheet is supported on a first support film, and an internal electrode paste on a second support film. A supported electrode material supply strip is provided.

Next, a unit sheet of a predetermined size of the ceramic green sheet is punched out from the sheet supply belt together with the first support film, and after adhering the unit sheet onto a support stand, a unit sheet of a predetermined size is supported on the unit sheet. By peeling off the film, the unit sheets are stacked on a support.

Next, an electrode material thermal transfer process is carried out in which unit electrode paste of a predetermined size is applied onto the unit sheet by thermal transfer from the electrode material supply band, so that the electrode paste is formed with deviations for every other layer in the stacking direction. Then, this unit sheet lamination process and electrode material thermal transfer process are repeated to obtain a ceramic green chip in which unit sheets are laminated with electrode paste formed in a manner that is shifted every other layer.

Furthermore, the ceramic raw chips are fired to obtain a sintered body,
Finally, an external electrode is applied to the outer surface of the sintered body.

[Function and Effects of the Invention] In this invention, the ceramic green sheets are not mechanically peeled off from the support film, but are piled up by pressure bonding for lamination. The sheet can be handled without worrying about its strength.

Furthermore, when applying internal electrode paste, dry thermal transfer is used instead of wet screen printing, which reliably prevents swelling caused by electrode paste printing and penetration of electrode paste into pinholes or pores. can do. Therefore, short circuits and reductions in breakdown voltage can be prevented, and a highly reliable multilayer capacitor can be manufactured.

Furthermore, since it uses thermal transfer rather than screen printing, a large number of internal electrodes can be dispersed and formed at precise pitches on a single ceramic green sheet during mass production.

In addition, the internal electrodes can be shifted in the direction of the vA layer by simply mechanically shifting either the layered side or the electrode material supply band side, so the internal electrodes can be placed accurately in the layered direction. It can be formed by shifting every other layer. Therefore, it is possible to dramatically improve the yield rate of multilayer capacitors.

[Explanation of Examples] A manufacturing method according to an embodiment of the present invention will be described below.

First, as shown in FIGS. 2 and 3, a sheet supply belt 3 in which a ceramic green sheet 2 was supported on a first support film 1, and an internal electrode paste 5 supported on a second support film 4. An electrode material supply band 6 is prepared. The first support film 1 can be constructed using a synthetic resin film such as polypropylene, and the ceramic green sheet 2 is supported by applying ceramic slurry to one side using a doctor blade. be able to.

On the other hand, the second support film 4 can also be constructed using a synthetic resin film such as polypropylene,
Using a doctor blade, apply Ag-
An electrode material supply band 6 is obtained by applying an internal electrode paste 5 containing Pd, Cu, etc. Internal electrode paste 5
can also be formed using a thin film forming method such as sputtering or vapor deposition.

Next, as shown in FIG. 1, a support table 8 as a work table is prepared on which the lamination work is performed. A film 9 whose upper surface is viscous is placed on the support base 8, and the film 9 is supported using a suction hole 10 connected to a suction means (not shown). It is fixed by suction to the base 8". The reason why the upper surface of the film 9 is configured to have viscosity is to fix the stacked ceramic unit sheets 2a (described later) using the viscosity.

A punching die 11 having a punch lla and a mounting frame llb is arranged above the support table 8. The sheet supply band 3 shown in FIG. 2 is placed on the placement frame llb of this punching die 11. Note that the punch lla is formed with an air intake hole 11c, and the air intake hole 11c is connected to a suction means (not shown).

Next, the sheet supply band 3 shown in FIG. 2 is placed on the placement frame 11b of the punching die 11 described above. Next, the punch lla is lowered and the ceramic unit sheet 2a of a predetermined size is punched out together with the first support film portion 1a of the same unit sheet size. The punched first support film portion 1a is held on the lower surface of the punch 11a by suction from the air intake hole 11C. Therefore, the unit sheet 2a and the first support film portion 1a do not fall downward.

Next, the punch lla is further lowered, and the unit sheet 2a is superimposed on the upper surface of the film 9, and is crimped.

Furthermore, after the pressure bonding, the punch lla is raised to peel the first support film portion 1a from the unit sheet 2a. This state is shown in FIG. As mentioned above, the upper surface of the film 9 is configured to have viscosity, so the stacked unit sheets 2a are stuck to the film 9 due to the viscosity, and the supporting film 1 and the unit sheets 2a are attached to each other. Since the strength of the adhesive force is not so strong, it is possible to peel off the first support film portion 1a while keeping the ceramic unit sheet 2a superimposed on the film 9 by raising the punch lla. ing.

Next, unit sheets 2b and 2c of a predetermined size are further laminated on the unit sheet 2a superimposed on the film 9 using the punching die 11, as shown in FIG.

In addition, the unit sheet (2) which is continuously laminated on the film 9
Since a...2c serves as an outer layer ceramic sheet, the number of laminated layers is arbitrary.

Next, the electrode material thermal transfer process shown in FIG. 6 is carried out. In this step, a thermal head 12 for thermal transfer of electrode material is placed above the support 8 . The thermal head 12 is
A heater 13 is built in, and the heater 13 is configured to heat the lower head surfaces 12a...12C. Further, the thermal head 12 is configured to be able to be driven back and forth in the vertical direction.

The electrode material supply band 6 shown in FIG. 3 is placed between the thermal head 12 and the support 8, and the electrode paste 5 is thermally transferred onto the upper surface of the unit sheet 2C stacked on the support 8. As a result, as shown in FIG. 6, unit electrode pastes 5a...5C are formed on the unit sheet 2C.

Next, as shown in FIG. 7, the unit sheet lamination process is carried out again. That is, a punching die 11 is placed above the support stand 8.
are arranged, the sheet supply band 3 is placed on the mounting frame llb, and the unit sheets 2d are stacked on the unit electrodes 5a...5C using the bunch lla, and are crimped and laminated.

Furthermore, the electrode material thermal transfer process is performed again.

That is, as shown in FIG. 8, the thermal head 12 is placed above the support stand 8, and the electrode material supply band 6 is placed between the thermal head 12 and the support stand 8, and the electrode paste 5 is thermally transferred. Then, the unit electrodes 5d...5f are stacked on the unit electrode 2d.

In this case, the unit electrodes 5d...5f must be formed laterally shifted from the previously formed unit electrodes 5a...5C. Therefore, the thermal head 12 is configured to be movable in the lateral direction, and in this electrode material thermal transfer process, it is placed to the right in the drawing compared to the process shown in FIG.

The electrode material thermal transfer process and sheet lamination process shown in FIGS. 5 to 8 described above are repeated as many times as necessary.

Furthermore, a step of continuously laminating only unit sheets from the ceramic green sheets 2 shown in FIG. 1 is carried out to obtain ceramic raw chips 20 shown in FIG. 9. The green ceramic chip 20 shown in FIG. 9 is compressed by applying pressure from above on the support stand 8, or by applying pressure after being removed from the support stand 8, and then
Cut along the dashed line A in the figure to obtain a plurality of unit green chips. A multilayer ceramic capacitor can be obtained by firing these at a predetermined temperature to obtain a ceramic sintered body, and finally applying external electrodes to the exposed outer surfaces of the internal electrodes.

In the above embodiment, the thermal head 12 for thermal transfer of electrode material
, a plurality of head contact surfaces 12a each having the size of a unit electrode.
12c was used, but as shown in FIG. 10, it is also possible to perform thermal transfer using a thermal head 22 having a flat head contact surface 22a. However, in this case, as the electrode material supply zone 26, the second
It is necessary to form unit electrode pastes 25a, .

In addition, in the electrode material thermal transfer process shown in FIG. 8, by moving the thermal head 12 in the lateral direction,
The unit electrodes 5d...5f were formed offset from the unit electrodes 5a...5C, but instead of the movement of the thermal head 12, the support stand 8 was configured to be movable laterally, and the support stand By moving 8, the internal electrodes can be similarly formed by shifting every other layer in the stacking direction.

Furthermore, regarding the method of fixing the unit sheet 2a that is first stacked on the support base 8 to the upper surface of the support base 8, it is not necessarily necessary to use the suction holes 8a to fix the unit sheet 2a by suction. The unit sheet 2a may be fixed to the support base 8 by using a film having the following properties.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the process of stacking unit sheets on a support base ÷ top in an embodiment of the present invention, FIG. 2 is a sectional view showing a sheet supply band, and FIG. 3 is a sectional view showing an electrode material supply band. FIG. FIG. 4 is a sectional view showing the state after the process shown in FIG. 1 is completed. FIG. 5 is a cross-sectional view for explaining a step of laminating a plurality of unit sheets, following the step of FIG. 4. FIG. 6 is a cross-sectional view showing the process of thermally transferring the electrode material. FIG. 7 is a sectional view showing a step of laminating unit sheets subsequent to the step of FIG. 6. FIG. 8 is a cross-sectional view for explaining the step of thermally transferring the electrode material again following the step of FIG. 7. FIG. 9 is a cross-sectional view for explaining the obtained ceramic green chip. 1st
FIG. 0 is a cross-sectional view for explaining a process of thermally transferring an electrode material using a thermal head of another shape.

Claims (1)

[Claims] A step of preparing a sheet supply band in which a ceramic green sheet is supported on a first support film and an electrode material supply band in which an internal electrode paste is supported in a second support film; and sheet supply. By punching out a unit sheet of a predetermined size of the ceramic green sheet together with the first support film from the band, pressing the unit sheet onto a support base, and then peeling off the support film of the unit size on the unit sheet, a step of stacking unit sheets on a support base; an electrode material thermal transfer step of applying unit electrode paste of a predetermined size from the electrode material supply band onto the unit sheet by thermal transfer; The unit sheet lamination step and the electrode material thermal transfer step are repeated so that the unit sheets are formed with a shift in every other layer, and the unit sheets are stacked through the electrode paste formed with a shift in every other layer. A method for manufacturing a multilayer ceramic capacitor, comprising: obtaining a raw ceramic chip; firing the raw ceramic chip to obtain a sintered body; and providing an external electrode to the sintered body.