JP2001143956A - Method of manufacturing laminated ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing laminated ceramic capacitor by which the positioning accuracy of green sheets can be improved at the time of laminating the green sheets upon another. SOLUTION: Dielectric paste 13 containing ceramic powder as a pigment is printed in a prescribed pattern on the surfaces of one kinds of green sheets 10 carrying ink stripes 12 on both ends. In this case, the paste 13 is printed in such a way that dielectric patterns 14 corresponding to internal electrode patterns formed on another kind of green sheets are positioned to the central parts of the sheets 10. At the time of providing, for example, hole sections 15 in marker forming parts outside the patterns 14, the hole sections 15 function as the markers of the dielectric printed sheets when the paste 13 is printed in such patterns that are designed to prevent the paste 13 from being printed. Then both kinds of green sheets are alternately laminated upon another by using the markers formed on internal electrode printed sheets and the markers formed on the dielectric printed sheets.

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 multilayer ceramic capacitor, and more particularly to a technique for improving the positioning accuracy when laminating green sheets.

[0002]

2. Description of the Related Art In response to demands for miniaturization and high performance, multilayer ceramic capacitors (MLCs) have been increasingly miniaturized and multilayered in recent years.
More than 0 layers appear. Such a laminated ceramic capacitor is formed by printing an internal electrode paste on a surface of a ceramic green sheet in a predetermined pattern, laminating a predetermined number of the internal electrode printed sheets together with a ceramic green sheet on which no paste is printed, pressing and firing. Thereafter, an external electrode paste is applied to the end surface of the fired chip and baked.

[0003] When the internal electrode printing sheet and the ceramic green sheet on which the paste is not printed are laminated, the internal electrode paste is applied so that the internal electrodes are alternately led out to opposite ends of the fired chip later. The printed portions are laminated so as to be shifted by a predetermined amount in the length direction of the laminated sheet. Further, the green sheet laminate as described above,
It is densified under high temperature and high pressure so that it is densely fired in the subsequent step, but due to its deformability, it is densified using a one-sided metal plate / one-sided rubber device.

However, the multilayer ceramic capacitor manufactured by the above-described manufacturing method has the following problems. That is, as the number of laminated sheets increases, the portion where the internal electrode paste is printed,
Since the difference in the thickness of the unprinted portion becomes remarkable, as shown in FIG. 5, in the final MLC chip, the take-out portion of the internal electrode is greatly bent (pillowing), and the element shape becomes a rectangular parallelepiped, The appearance was deformed.

Further, as shown in FIG. 6, in the green sheet laminate, pressure is not sufficiently applied to a concave portion caused by a difference in thickness between a portion where the internal electrode paste is printed and a portion where the internal electrode paste is not printed. The sintering of the part was insufficient. Further, when the green sheet laminate is compressed under high temperature and high pressure, the force applied to the internal electrode portion becomes uneven, so that the internal electrode is distorted or peeled.

In order to solve such problems, the present inventors have previously proposed a method for manufacturing a multilayer ceramic capacitor as described below. That is, first, as shown in FIG. 7A, the internal electrode paste 2 is formed on the green sheet 1 by printing or the like (the internal electrode printing sheet “S”).
1 "). Next, as shown in FIG. 7 (B), when the internal electrode printing sheet is laminated on another green sheet,
A dielectric paste 3 using a ceramic powder as a pigment is formed by printing or the like on a portion of the internal electrode printing sheet that does not overlap with the internal electrode paste portion (the dielectric printing sheet “S”).
2 "). Then, as shown in FIG. 7 (C), the dielectric printed sheet and the internal electrode printed sheet are aligned so that the internal electrode paste portion and the dielectric paste portion do not overlap. They are alternately stacked.

[0007]

Conventionally, when stacking green sheets, a marker 4 as shown in FIG. 8, for example, as shown in FIG. 8, is provided outside the internal electrode pattern so that the position of the internal electrode pattern can be detected. Two or more are printed. Then, the position of the internal electrode pattern is detected by the two or more markers 4, and the movable table on which the green sheet is installed is moved up and down and diagonally to set the internal electrode pattern at a predetermined position. Have been.

As described above, the marker is used for positioning,
The reason for not using the internal electrode pattern itself is as follows. That is, in order to detect the position from the pattern formed on the green sheet, it is necessary to find the center point of this pattern by image processing and detect the position based on the center point. Therefore, as a pattern used for positioning, a pattern that is as small as possible and that makes it easy to find the center point is preferable because image processing is simple. for that reason,
As a pattern used for positioning, a circular pattern or a cross pattern as shown in FIG. 8 is used instead of the internal electrode pattern itself.

Note that this marker is for detecting the position of the internal electrode, and the positional relationship with the internal electrode is important. Therefore, usually, the marker is printed together with the internal electrode pattern on a screen on which the internal electrode is printed. A pattern is formed and both are printed simultaneously. Therefore, the same ink as the internal electrode paste is used as the ink for this marker.

However, in the manufacturing method proposed by the present inventors, the above-mentioned marker is formed only on the internal electrode printing sheet, and if there is no marker on the dielectric printing sheet, the internal electrode paste portion and the dielectric When the two sheets are alternately laminated while being aligned so that the paste portion does not overlap with the paste portion, in the dielectric printing sheet shown in FIG. The position must be detected by the shadow due to the unevenness with the missing part. However, this method requires a high-precision CCD sensor and high-performance image processing capability,
There is a problem that the reading error tends to increase, and as a result, the effect of the above-described manufacturing method cannot be sufficiently obtained.

The present invention has been proposed to solve the above-mentioned problems, and an object of the present invention is to manufacture a multilayer ceramic capacitor capable of improving the positioning accuracy when laminating green sheets. It is to provide a method.

[0012]

In order to achieve the above object, an invention according to claim 1 is characterized in that an internal electrode printing sheet formed by printing an internal electrode paste on a ceramic green sheet in a predetermined pattern is provided separately. A dielectric printed sheet obtained by printing a dielectric paste on a portion not overlapping with the internal electrode paste portion when the internal electrode printed sheet is laminated on the ceramic green sheet, the internal electrode paste portion and the dielectric paste In a method for manufacturing a laminated ceramic capacitor in which portions are aligned and laminated so as not to overlap with each other, a colored ink is applied to both ends of a ceramic green sheet constituting the dielectric printing sheet, and a predetermined ink is applied on the colored ink. The dielectric paste is printed so as to form a hole having the shape shown in FIG. As markers for alignment of the dielectric printing sheet click, it is characterized in that laminating a dielectric printing sheet and the internal electrode-printed sheet.

According to the first aspect of the present invention having the above-described structure, it is possible to form a marker on the dielectric printing sheet by a simple operation process, and to position the internal electrode printing sheet and the dielectric printing sheet. The alignment can be performed accurately. As a result, at the time of pressing, the part of the internal electrode printing sheet where the internal electrodes are not formed and the dielectric paste part of the dielectric printing sheet can be accurately overlapped, so that the internal electrode printing sheets alternately stacked Since the difference in thickness between the printed part and the non-printed part of the internal electrode paste between the sheet and the dielectric printed sheet is offset, the pilling up and down of the laminate is greatly reduced, and the appearance is poor. Is improved. Further, since the pressing pressure at the time of forming the laminate is also applied uniformly, the distortion of the laminate is reduced, and the occurrence of internal structural defects can be reduced.

According to a second aspect of the present invention, in the method of manufacturing a multilayer ceramic capacitor according to the first aspect, the dielectric paste is made of the same material as the ceramic green sheet. It is. According to the second aspect of the present invention, the dielectric paste formed on the ceramic green sheet to absorb the influence of the thickness of the portion where the internal electrode paste is formed is replaced with the ceramic green sheet. By using the same material as above, the physical properties of the dielectric paste portion and the ceramic green sheet portion can be made equal, so that the pressing pressure and the like at the time of forming the laminate can be made uniform over the entire surface of the green sheet laminate. .

According to a third aspect of the present invention, in the method for manufacturing a multilayer ceramic capacitor according to the first or second aspect, the hole has a circular or cross shape. . According to the third aspect of the present invention having the above configuration, the shape of the marker formed on the dielectric printing sheet can be made small and a pattern in which the center point can be easily found can be obtained. Image processing becomes simple.

[0016]

Embodiments of the present invention will be specifically described below with reference to the drawings.

[Formation of Marker on Dielectric Printed Sheet]
As shown in FIG. 1, a sponge 11 impregnated with an aqueous black ink is applied to both ends of a green sheet 10 on which a dielectric pattern is to be printed, and the green sheet 10 is horizontally (rightward in the figure) in this state. To form band-shaped black ink streaks 12 at both ends of the green sheet 10.

Subsequently, as shown in FIG. 2, a dielectric paste 13 made of a ceramic powder as a pigment is printed in a predetermined pattern on the surface of the green sheet 10 having band-shaped black ink streaks 12 formed at both ends. In this case, the dielectric pattern 14 corresponding to the internal electrode pattern shown in FIG.
(FIG. 7B) is formed so as to be located at the center of FIG. Further, a printing pattern designed to prevent the dielectric paste 13 from being printed, for example, by providing a hole in the marker forming portion outside the dielectric pattern 14,
The dielectric paste 13 is printed. Then, by cutting along the dotted line in FIG. 2, a dielectric printed sheet “S2” as shown in FIGS. 3A and 3B is obtained.

In this embodiment, a circular hole 15 is formed outside the dielectric pattern 14 and the hole 1 is formed.
5, the belt-like black ink streaks 12 applied to both ends of the green sheet 10 can be seen. As a result, this circular hole 15 functions as a marker of the dielectric printing sheet.

[Green Sheet Laminating Method] (a) First, the marker 15 of the green sheet (dielectric printed sheet “S2”) shown in FIG. 3 is detected using a CCD sensor or the like, and the position is read. Then, the dielectric print sheet "S2" is gripped by a jig having a suction mechanism. At this point, the dielectric printed sheet “S”
The 2 "pattern (the portion on which the dielectric paste is printed) has some misalignment. This misalignment is calculated from a position read by a CCD sensor or the like.

(B) Next, the jig is moved to a movable table. At this time, the previously calculated displacement is corrected by moving the table up, down, left, right, and diagonally, and the dielectric printing sheet “S2” is placed on the table. It is needless to say that the table may be moved as described above or the jig may be moved to correct the positional deviation.

(C) Next, the same operation is performed for the internal electrode printing sheet "S1" shown in FIG. 8, and the positioning between the two is performed by using the markers formed on both sheets, and the table is already set. The internal electrode printing sheet “S” is placed on the dielectric printing sheet “S2” of FIG.
Then, in order to press the superposed dielectric print sheet “S2” and the internal electrode print sheet “S1” under pressure, press the top of the internal electrode print sheet “S1”.

(D) Next, the above operations (a) and (b) are performed, and the internal electrode printing sheet “S” pressed in (c) is pressed.
3 is pressed on the dielectric printed sheet "S2" of Fig. 3. Similarly, the internal electrode printed sheet "S1" and the dielectric printed sheet "S2" are alternately laminated and pressed. On the top and bottom of the laminate, several unprinted green sheets are laminated and pressed, and the laminated and pressed body is cut into a predetermined size and fired to form external electrodes on both ends. Then, a multilayer ceramic capacitor is produced.

In the case of a multilayer ceramic capacitor, since the internal electrodes are laminated one by one in the length direction while being shifted by a predetermined amount, the internal electrode printing sheet “S1” and the dielectric printing sheet “ S2 "are stacked. In the present embodiment, the dielectric printing sheet “S2” of FIG.
Started from the operation of laminating the internal electrode printing sheet “S1” on the internal electrode printing sheet, but may start from the operation of laminating the dielectric printing sheet “S2” of FIG. 3 on the internal electrode printing sheet “S1”. It is needless to say that the same lamination and press body can be obtained by repeating the lamination and press similarly.
Further, since the portion to be a multilayer ceramic capacitor is the portion of the dielectric pattern 14 in FIG. 2, the portion to which the aqueous black ink is applied is a portion that is finally discarded.

[Operation / Effect] When the above-described green sheet laminating method is used, the internal electrode printing sheet “S1” and the dielectric printing sheet “S2” are accurately aligned, so that pressing is performed. At this time, the portion of the internal electrode printing sheet where the internal electrodes are not formed and the dielectric paste portion of the dielectric printing sheet exactly overlap. As a result, the difference in thickness between the portion where the internal electrode paste is printed and the portion where the internal electrode paste is not printed is offset between the alternately laminated internal electrode print sheet “S1” and the dielectric print sheet “S2”. For this reason, the concave portion shown in FIG. 6, which has conventionally been a problem, is not formed. As shown in FIG. 4, the upper and lower pillowings of the laminate are greatly reduced, and the appearance defect is improved.

Further, since the difference in thickness at the portion where the internal electrode paste is printed is absorbed, the pressing pressure during the formation of the laminate is evenly applied, and the distortion of the laminate is reduced, thereby reducing the occurrence of internal structural defects. it can. Furthermore, since the permeation of water and plating solution from between the alternately laminated internal electrode printing sheet and dielectric printing sheet is prevented, the reliability is greatly improved.

[Other Embodiments] It is needless to say that the same effects can be obtained by appropriately changing the thickness, the number of layers, the firing conditions, and the like of the ceramic green sheets. Further, the shape of the marker formed on the dielectric printing sheet “S2” is not particularly limited as long as it can accurately align with the internal electrode printing sheet “S1”.

[0028]

As described above, according to the present invention,
It is possible to provide a method for manufacturing a multilayer ceramic capacitor capable of improving the positioning accuracy when laminating green sheets.

[Brief description of the drawings]

FIG. 1 is a diagram showing a process of applying black ink streaks to a green sheet forming a dielectric printing sheet.

FIG. 2 is a view showing a state where a dielectric paste is printed on the green sheet shown in FIG. 1;

FIG. 3 is a view showing a dielectric printed sheet on which a marker is formed.

FIG. 4 is a view showing a state after sintering of a green sheet laminate produced by the production method of the present invention.

FIG. 5: Final MLC produced by a conventional production method
Side view of chip

FIG. 6 is a view showing a state after sintering of a green sheet laminate manufactured by a conventional manufacturing method.

7A and 7B are diagrams illustrating an example of a method for manufacturing a multilayer ceramic capacitor, wherein FIG. 7A is a plan view illustrating an internal electrode printing sheet, FIG. 7B is a plan view illustrating a dielectric printing sheet,
(C) is a sectional view showing a laminated state of the dielectric printing sheet and the internal electrode printing sheet.

FIG. 8 is a view showing an internal electrode printing sheet on which a marker is formed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Green sheet 2 ... Internal electrode paste 3 ... Dielectric paste 4 ... Marker 10 ... Green sheet 11 ... Sponge 12 ... Strip-shaped black ink stripe 13 ... Dielectric paste 14 ... Dielectric pattern 15 ... Marker

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yukihiro Sato 1-167, Higashi-Ome, Ome-shi, Tokyo 1 Inside Nippon Chemi-Con Corporation (72) Inventor Minoru Fujii 1-167, Higashi-Ome, Ome-shi, Tokyo 1 Japan Within Chemicon Co., Ltd. (72) Inventor Yohachi Yamashita 70, Yanagicho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Yanagicho Plant Co., Ltd. Terms (Reference) 5E001 AB03 AD02 AD05 AF06 AH00 AH01 AH05 AH06 AH09 AJ01 AJ02 5E082 AB03 BC19 BC33 BC38 EE04 EE35 FG06 FG18 FG26 FG46 FG54 GG10 JJ03 LL01 LL03 MM11 MM13 MM21 MM22 MM23

Claims (3)

[Claims] 1. An internal electrode printing sheet formed by printing an internal electrode paste in a predetermined pattern on a ceramic green sheet, and the internal electrode paste portion when the internal electrode printing sheet is laminated on another ceramic green sheet. A method for manufacturing a laminated ceramic capacitor, comprising: positioning a dielectric printing sheet obtained by printing a dielectric paste on a portion that does not overlap with a dielectric paste portion such that the internal electrode paste portion and the dielectric paste portion do not overlap with each other; In, a colored ink is applied to both ends of a ceramic green sheet constituting the dielectric printing sheet, and the dielectric paste is printed on the colored ink so that a hole having a predetermined shape is formed, The colored ink visible from the holes is used as a marker for positioning the dielectric printed sheet, Method of manufacturing a multilayer ceramic capacitor, which comprises laminating a printing sheet and the internal electrode-printed sheet. 2. The method according to claim 1, wherein the dielectric paste is made of the same material as the ceramic green sheet. 3. The method of manufacturing a multilayer ceramic capacitor according to claim 1, wherein the shape of the hole is a circle or a cross.