JPH08186051A - Production of multilayer ceramic device - Google Patents

Abstract

PURPOSE: To obtain a highly reliable laminate having uniform inner electrode structure by eliminating the difference of thickness between the central part and the end part of a ceramic green sheet when a multilayer laminate is formed by screen printing thereby obtaining a flat surface and printing the inner electrode stably. CONSTITUTION: Screen printing is carried out using a screen having mesh 3 smaller in the vicinity of a resist 2 for forming a screen pattern 1 than in the central part of the pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a laminated ceramic part formed by using a screen printing method.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a laminated body such as a laminated ceramic capacitor or laminated inductor having a structure in which a metal conductor layer and a ceramic insulating layer are alternately laminated inside, a ceramic green sheet is prepared by a doctor blade method. There is known a green sheet method in which a conductor layer is printed on this sheet and laminated to obtain a laminate. However, there has been a great demand for miniaturization of chips in recent years, and in order to meet this demand, thinning of the ceramic insulating layer and more multilayers have become indispensable conditions. When the thickness of the ceramic insulating layer is 10 μm or less, when the conventional doctor blade method is used to manufacture the green sheet, the strength of the green sheet cannot withstand handling, and the green sheet is peeled from the release film. However, there is a problem in handling that the green sheet is destroyed, and it is difficult to establish mass production conditions including problems in equipment. Therefore, as a method for manufacturing a laminated body made of a green sheet having a film thickness of 10 μm or less, a screen printing method is commonly used in which the laminated body is formed by alternately repeating the print drying of the ceramic paste and the print drying of the conductor paste. Became.

By the way, when the ceramic paste is printed and dried by the screen printing method to form a ceramic green sheet having a relatively large area, the thickness of the end portion of the printed green sheet becomes larger than that of the central portion.
It becomes difficult to obtain a uniform thickness over the entire surface of the green sheet. This is because the emulsion (resist) that forms the pattern of the screen used is stretched by the squeegee during printing, so the discharge rate of the ceramic paste is larger near the boundary between the screen mesh and the resist parallel to the squeegee, and therefore the pattern edge part. This is because it will be printed thick. Then, when green sheets are stacked in the same pattern as they are to proceed with multi-layering, the difference in thickness between the central portion and the end portion of the laminated body is accumulated, and the sectional shape of the laminated body becomes arcuate due to the thickness distribution. Will end up. In this situation, print the internal electrode paste on the surface of the green sheet.
When dried and laminated repeatedly, the internal electrode pattern printed on the end of the ceramic pattern is misaligned,
It is not possible to obtain a uniform internal electrode structure. Furthermore, when trying to form the internal electrode structure by ignoring the accumulated thickness difference due to stacking, some parts of the stack may not be printed with the internal electrode pattern, or in the worst case, ceramic paste or internal electrode paste may be printed. When doing so, there is a problem in that the laminated body cannot be actually manufactured because the screen is damaged due to poor flatness of the printed body.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to alleviate a difference in thickness between a pattern central portion and an end portion of a green sheet, which occurs when a ceramic paste is printed in forming a multilayer laminate by a screen printing method. Another object of the present invention is to provide a method of manufacturing a highly reliable laminated ceramic component by preventing the thickness difference from accumulating due to lamination and ensuring a uniform internal electrode structure.

[0005]

According to the present invention, in order to reduce the difference in thickness between the central portion of the laminate and the end portions of the pattern, which occurs at the time of printing and laminating, when forming the ceramic green sheet, The ceramic paste is printed using a screen in which the openings of the mesh at the end of the screen pattern adjacent to the resist are smaller than the openings of the mesh at the center of the screen pattern. When a ceramic green sheet is formed with this screen, it is possible to suppress the discharge amount of the excessive ceramic paste at the pattern end that is caused by the mesh and resist being pushed and stretched by the squeegee in the squeegee advancing direction. It is possible to reduce the difference in thickness between the central portion and the end portion of the ceramic laminated body that occurs when printing and laminating, and to ensure a uniform internal electrode structure.

[0006]

Embodiments of the present invention will be described below with reference to the drawings, taking the production of a laminated ceramic capacitor as an example.

2A and 2B are views for explaining a part of a method of manufacturing a multilayer ceramic capacitor according to a conventional method. FIG. 2A shows a screen pattern 1 for a ceramic paste, and FIG. 2B shows a screen pattern parallel to a squeegee of the screen pattern. Na resist 2
The mesh openings in the vicinity are shown. In addition, (c) uses this screen pattern to make the ceramic insulating layer 4
FIG. 3 is a cross-sectional view of a laminated body produced by forming a layer, forming an internal electrode 5 thereon, and repeating lamination.

FIG. 1 is a diagram for explaining the manufacturing method of the present invention.
(A) shows a screen pattern 1 for a ceramic paste, (b) shows an opening of a mesh near the resist 2 of this screen pattern, and (c) is a cross-sectional view of a laminate produced by using this screen pattern. Is shown.

In the experiments of the above-mentioned two examples, a compound having a Pb-based composite perovskite structure was used as the ceramic powder, and ethyl cellosolve was used as a solvent and butylphthalic acid was used as a plasticizer in a dispersion facility such as a high speed homomixer or a bead mill. Polyvinyl butyral as the organic resin and the ceramic powder were put into a solvent containing butyl glycolate to prepare a ceramic paste. Further, a mixed powder having a mixing ratio of Ag 80 wt% and Pb 20 wt% was used for the internal electrodes, ethyl cellulose was used as the organic resin, and α-terpineol was used as the solvent, and a paste kneaded with three rolls was used.

In both of the two examples, the ceramic paste printing screen was coated with stainless steel # 200 mesh on a 320 mm square frame and had a resist thickness of 10 μm.
m. The pattern shape was a square of 100 mm × 100 mm, and the screen for internal electrode paste used was a screen made so as to be within 100 mm × 100 mm of the above screen pattern. The mesh of the pattern edge parallel to the squeegee of the ceramic paste printing screen according to the method of the present invention was subjected to nickel plating treatment of 5 μm so that the center of the opening was 85 μm and the edge was 7 μm.
It was 5 μm. In addition, when a laminate is manufactured by the conventional method,
Since it is known that the ridges at the ends of the surface of the laminated body are generated from the ends to the central part over 400 to 500 μm, the plating width is set to 450 μm.

The printing is carried out by first setting the conditions so that the thickness of the ceramic paste is 10 μm when the ceramic paste is printed and dried once, and then the ceramic paste is printed 30 times to form a protective layer having a thickness of 300 μm. A ceramic layer was prepared. Next, print the effective layer that forms the capacitor
It was made. That is, an internal electrode having a thickness of 1.5 μm was formed on the protective layer prepared above by using an internal electrode paste screen, and then the ceramic paste was printed and dried to obtain 10
A ceramic insulating layer of μm was formed. Further, an internal electrode was formed so as to face the internal electrode formed earlier, and this process was repeated 61 times to produce 60 layers of effective layers as a capacitor. Finally, the ceramic paste was repeatedly printed and dried 30 times to form a protective layer, and a laminated body of a laminated ceramic capacitor was obtained.

When the ceramic paste is printed on the conventional mesh-shaped screen shown in FIG. 2B, the end surface of the resist at the pattern end portion parallel to the squeegee is originally printed on the printed surface as the screen is stretched by the squeegee. What was vertical, the printing surface side tilted to the outside of the pattern,
As a result, the discharge amount of the ceramic paste becomes larger at the end portion of the pattern parallel to the squeegee than at the central portion of the pattern, resulting in a difference in thickness. When multiple coatings are further applied, the thickness difference is accumulated, resulting in the thickness difference shown in Table 1. Therefore, when the internal electrodes are printed, the flatness of the printed body is deteriorated by the thickness difference, so that a stacking deviation occurs near the end of the pattern.

When printing with a screen having a mesh opening near the resist according to the present invention shown in FIG. 1 (b), when the screen is stretched by a squeegee, even if the end face of the resist is inclined, the mesh opening is formed. Since it is designed to be small, the ejection amount does not increase unlike the conventional case, and it is possible to prevent the thickness difference and the stacking deviation of the internal electrodes from occurring. Table 1 shows the thickness of the central portion of the laminated body, the thickness in the vicinity of the end portions of the pattern, and the displacement of the internal electrodes, which were generated in the case of this experiment, in comparison with the conventional method.

[0014]

[Table 1]

Here, as shown in FIGS. 1 (c) and 2 (c), t ₁ is the normal thickness of the laminate (the thickness of the central portion).
And t ₂ is the thickness including the raised portion at the end, and therefore t ₂ −t ₁ indicates the magnitude of the raised portion. l is an amount indicating the stacking deviation of the internal electrodes.

As can be seen from Table 1, in the conventional method, about 0.
While the thickness difference t ₁ -t _{2 of} 5 mm occurs, the thickness difference of about 0.1 mm can be suppressed in the present invention. Further, the stacking deviation of the internal electrodes caused by the thickness difference was reduced to 1/2 or less. Further, this laminated body was cut into chips, organic components were removed at 400 ° C., and after firing at 900 ° C., external electrodes were formed at the ends to obtain laminated capacitors. The results of a humidity resistance test (temperature 85 ° C., humidity 90%, rated voltage × 1) of this multilayer capacitor are shown in addition to Table 1. It is shown that the present invention in which the stacking deviation of the internal electrodes is smaller is more effective in the moisture resistance.

Further, in the case of the laminated body according to the conventional method, the effective area for printing the internal electrodes about 10 mm inward from the end portion of the laminated body is taken into consideration in consideration of the misalignment of the internal electrodes caused by the thickness difference and the situation in which printing is impossible. However, since the thickness difference from the pattern end is reduced by the present invention, the internal electrodes can be printed in the vicinity of the pattern end, and the loss part that does not form the capacitor of the laminated body is about 10% smaller than the conventional one. There was also the effect that it became 1/3. It goes without saying that the present invention can be applied not only to the laminated body of the laminated ceramic capacitor but also to all printed bodies and printed laminated bodies using the screen printing method.

[0018]

As described above, according to the present invention, a laminated body having a small thickness difference between the central portion and the end portion of the laminated body is produced when producing a laminated body of a laminated ceramic capacitor by a screen printing method suitable for forming a thick film. It has become possible to provide a manufacturing method that

[Brief description of drawings]

FIG. 1 is an explanatory view when a laminate is produced by the method of the present invention. FIG. 1A is a diagram showing a ceramic paste screen pattern. (B) is a figure which shows the opening of the mesh adjacent to a pattern edge resist. (C) is sectional drawing of a laminated body.

FIG. 2 is an explanatory diagram of a case where a laminated body is manufactured by a conventional method. FIG. 2A is a diagram showing a ceramic paste screen pattern. (B) is a figure which shows the opening of the mesh adjacent to a pattern edge resist. (C) is sectional drawing of a laminated body.

[Explanation of symbols]

1 Screen Pattern 2 Resist (Emulsion) 3 (Screen) Mesh 4 Ceramic Insulation Layer 5 Internal Electrode t ₁ Central Thickness t ₂ Edge Thickness l Internal Electrode Lamination Misalignment

Claims (1)

[Claims] 1. A method for producing a laminated ceramic component by a screen printing method using a paste containing either a metal powder or a non-metal powder as a main component, wherein a mesh in the vicinity of a resist forming a screen pattern is formed. A method for manufacturing a monolithic ceramic component, characterized in that an opening whose mesh is smaller than that of a mesh in the center of the pattern is used.