JPH047574B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method of manufacturing a multilayer ceramic capacitor.

Summary of the Invention The present invention provides a method for manufacturing a laminated ceramic capacitor, in which a plurality of ceramic green sheets each having a conductive film to be an internal electrode formed on the surface thereof are laminated to obtain a plurality of laminated ceramic capacitors. When cutting the body, cut so that the conductive film is exposed even on the side where the external electrode is not formed, and then apply ceramic slurry to the side, so that the side where no connection with the external electrode is desired is exposed. This is intended to prevent exposure of the internal electrodes and to obtain capacitance by effectively utilizing the entire width of the ceramic layers constituting the cut laminate.

BACKGROUND ART Conventionally, when mass-producing laminated ceramic capacitors on a factory scale, a plurality of ceramic green sheets 1 as shown in FIG. 10 are prepared. On this ceramic green sheet 1, a plurality of conductive films 2 to serve as internal electrodes are printed so as to be arranged vertically and horizontally with gaps 3 and 4 interposed therebetween, respectively. Such a plurality of ceramic green sheets 1 are laminated, cut along cutting lines extending in the vertical and horizontal directions, and then fired, and then external electrodes 5 are applied as shown in FIG. be done.

When laminating the ceramic green sheets 1 described above, the gap 3 on one ceramic green sheet 1 is stacked on another ceramic green sheet 1.
It is aligned with the upper conductive film 2 in the stacking direction. When such a laminate is cut along cutting lines passing through the gaps 3 and 4, a laminate chip 6 as shown in FIGS. 11 and 12 is obtained. FIG. 11 is a longitudinal cross-sectional view of the laminate chip 6, and FIG. 12 is a cross-sectional view thereof.

As is clear from FIGS. 11 and 12,
A plurality of internal electrodes 7 derived from the above-mentioned conductive film 2 are formed inside the laminate chip 6, and each internal electrode 7 faces each other with a ceramic layer 8 derived from the above-mentioned ceramic green sheet 1 interposed therebetween. are doing. Further, some of the internal electrodes 7 are connected to one external electrode 5, and other internal electrodes 7 are connected to the other external electrode 5.

In FIG. 12, the width G where the internal electrodes 7 are not formed is called the gap margin.
This is derived from gap 4 in Figure 0. Such a gap margin G is determined by taking into account the printing accuracy of the conductive film 2 as well as the deviation in the stacking of the ceramic green sheets 1. As long as the manufacturing method described above is adopted, this gap margin G is Existence is essential. That is, if the gap margin G is smaller than the predetermined value, as shown in FIG.
may be exposed on the side of the laminate chip 6,
Undesirable.

Problems to be Solved by the Invention The necessary dimensions for the gap margin G as described above are absolutely determined, almost regardless of the size of the multilayer ceramic capacitor, that is, the multilayer chip 6. Therefore, it can be seen that especially in a small-sized multilayer ceramic capacitor, the ratio of the width W2 of the internal electrode 7 to the width W1 of the multilayer chip 6 shown in FIG. 12 becomes small. Therefore,
The acquisition efficiency of capacitance with respect to the volume of the multilayer chip 6 is low, especially in the case of a small multilayer ceramic capacitor. Furthermore, due to misalignment or variation in the printing of the conductive film 2 in FIG. 10, or misalignment or variation in the stacking of the ceramic green sheets 1, alignment of the internal electrodes 7 in the stacking direction deteriorates as shown in FIG. , the overlapping area of each internal electrode 7 may become small.
In this case as well, this causes a decrease in the capacitance acquisition efficiency with respect to the volume of the multilayer chip 6 described above, and also causes variations in capacitance among the obtained multilayer ceramic capacitors.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for manufacturing a multilayer ceramic capacitor, which can increase capacitance acquisition efficiency and reduce variations in capacitance.

Means for Solving the Problems First and second external electrodes are formed on each end face of a laminate having internal electrodes facing each other interposed therebetween via a ceramic layer, and on each end face, an internal electrode is formed. In a method of manufacturing a multilayer ceramic capacitor in which a first group of electrodes is connected to a first external electrode and a second group of electrodes are connected to a second external electrode, the present invention provides the following steps. It is characterized by having the following steps. That is, (1) a step of preparing a plurality of ceramic green sheets in which a plurality of conductive films to be internal electrodes are formed in a line in a first direction, each spaced apart from each other via a gap; (2) (3) forming a laminate by laminating a plurality of ceramic green sheets so that the gap on one ceramic green sheet and the conductive film on another ceramic green sheet are aligned in the lamination direction; (3) cutting the laminate in the thickness direction along at least one cutting line oriented in the first direction to form a laminate block, the first cut thereby forming at least one side of the laminate block; A step of exposing the conductive film on the surface; (4) A step of covering the first cut surface with ceramic slurry; (5) A step of placing the laminate block to which the ceramic slurry has been applied intersecting the first direction. forming a laminate chip by cutting the laminate chip in the thickness direction at a position passing between the gaps by at least two cutting lines oriented in a second direction such that the laminate chip (6) a step of firing the laminate chip; and (7) providing first and second external electrodes on both end faces of the stacked laminate chips, respectively.

Effect: In this invention, when cutting a laminate of ceramic green sheets in which a conductive film to be an internal electrode is formed, the conductive film is actively exposed on the side surface where the external electrode is not formed. The process involves forming a cut surface on the surface and then covering the cut surface with ceramic slurry. Therefore, it is not necessary to form the conductive film taking into account the gap margin G shown in FIG.

Embodiment FIGS. 1 to 7 sequentially illustrate each process for manufacturing a multilayer ceramic capacitor according to an embodiment of the present invention.

First, a plurality of ceramic green sheets 11 as shown in FIG. 1 are prepared. A plurality of conductive films 12 to serve as internal electrodes are formed on each ceramic green sheet 11 by printing, for example, in a manner that they are spaced apart from each other via gaps 13 and lined up in a first direction, that is, in a horizontal direction. In this example, as will be clear from the explanation given later,
In order to obtain a large number of laminated ceramic capacitors at the same time, each conductive film 12 is formed to extend vertically in a strip shape.

After drying the printed conductive film 12, a plurality of ceramic green sheets 11 are stacked in a positional relationship as shown in FIG. In this embodiment, conductive films 12 formed with the same pattern are used.
A predetermined number of ceramic green sheets 11 having the same shape are stacked while changing their orientation by alternately rotating them by 180 degrees in a horizontal plane. In this stacked state, the gap 13 on one ceramic green sheet 11 and the conductive film 12 on another ceramic green sheet 11 (approximately the center of the conductive film 12 in this example) become aligned in the stacking direction. . Furthermore, on the upper and lower surfaces of the ceramic green sheets 11 laminated in this way,
If necessary, a predetermined number of ceramic green sheets on which no conductive film is formed are stacked.

When the ceramic green sheets 11 stacked in this manner are pressed and bonded together, they form a laminate 14 as shown in FIG. 3.
In this laminated body 14, the positional relationship of each conductive film 12 and gap 13 is schematically shown.

The laminate 14 shown in FIG. 3 is then cut through its thickness by the laterally oriented cutting line 15 shown in FIG. 1, thereby creating a longitudinal laminate as shown in FIG. A body block 16 is formed. The conductive film 12 is exposed at a cut surface 17 along the cutting line 15 forming the side surface of the laminate block 16.

Next, as shown in FIG. 5, ceramic slurry 18 is applied to both cut surfaces 17 of the laminate block 16.
is applied. The thickness of this ceramic slurry 18 is selected to be about 50 to 100 μm, and particularly preferably about 50 μm.

The ceramic slurry 18 described above is preferably made of the same ceramic material as the ceramic green sheet 11. That is, if the ceramic green sheet 11 and the ceramic slurry 18 are made of the same ceramic material, they can be fired under the same conditions in the firing process described later, and the ceramic green sheet 11 and the ceramic slurry 18 can be fired under the same conditions. This is because no abnormal reactions occur at the boundary.

Further, the binder contained in the ceramic slurry 18 is preferably specified as either an organic solvent-based binder or a water-soluble binder, in relation to the binder used in the ceramic green sheet 11. That is, as the binder used in the ceramic slurry 18, if the ceramic green sheet 11 uses an organic solvent-based binder such as polyvinyl alcohol or polyvinyl butyral, a water-soluble binder such as polyvinyl acetate may be used. If a water-soluble binder is used for the ceramic green sheet 11, it is preferable to use an organic solvent-based binder for the ceramic slurry 18. This is to prevent the binder of the ceramic slurry 18 from dissolving the binder of the ceramic green sheet 11.

Next, the laminate block 16 shown in FIG.
The cutting line 19 shown in FIGS. 1 and 3, i.e. the cutting line 1 pointing in the transverse direction, which is the first direction mentioned above.
A cut is made in the thickness direction at a position passing through the gap 13 by a cutting line oriented in the longitudinal direction, which is the second direction intersecting the gap 13. As a result, a laminate chip 20 as shown enlarged in FIG. 6 is obtained.
Cut surfaces 21 forming both end surfaces of this laminate chip 20
A conductive film 12, which is to become an internal electrode, is exposed in each of the electrodes. Note that different conductive films 12 are exposed on each of the two cut surfaces 21.

A laminate chip 20 as shown in FIG. 6 is fired. Then, external electrodes 22 and 23 are formed on each end face of the fired laminate chip 20.
The external electrodes 22 and 23 can be formed by applying or baking a metal paste, or by plating. When the external electrodes 22 and 23 are formed in this way, the first group of internal electrodes provided with the conductive film 12 formed inside the stacked chip 20 are connected to the first external electrode 22. Similarly, the second group of capacitors are connected to the second external electrode 23 to form a multilayer ceramic capacitor.

Although the invention has been described in connection with preferred embodiments, other embodiments are possible within the scope of the invention.

For example, the laminate block 16 shown in FIG.
In the step of forming the laminate block 16, both sides of the laminate block 16 were formed by cut surfaces 17 cut along the cutting line 15, but it was possible to cut only one side of the laminate block 16 as a result. The ceramic green sheet may be constructed of a cut surface with a cut surface, and the other side surface may be constructed of the edge itself of the ceramic green sheet.
Further, while the other side surface is formed by a cut surface, the cut may be made at a position where the conductive film to be an internal electrode is not exposed there. According to such an embodiment, a formation state like that of the internal electrode 7 shown in FIG. 13 can be obtained, but
With this, at least one gap margin G (Fig. 12) is eliminated, and compared to the conventional case where there is a gap margin G on both sides of the internal electrode, the capacitance acquisition efficiency is improved and the electrostatic capacitance is Variations in capacity are also relatively small. Note that when the conductive film is exposed only on one side of the laminate block, it is of course necessary to apply the ceramic slurry only to the side where the conductive film is exposed.

Effects of the Invention As described above, according to this invention, in short,
Since the internal electrodes can be formed over the entire width of the stacked chip, the efficiency of acquiring capacitance relative to the volume of the stacked chip is improved, and variations in capacitance between products can be minimized. can. This will be explained in more detail with reference to FIGS. 8 and 9.

8 and 9 are two-dimensional diagrams showing the relationship in size between the ceramic portion 24 and the internal electrode 25, in order to clarify the comparison between multilayer ceramic capacitors having the same external dimensions. ,
The planar dimensions of the ceramic portion 24 are shown to be identical. The region where the internal electrode 25 is formed is shown by hatching, and the internal electrode 25 hidden inside the ceramic portion 24 is shown by a dotted line. Note that the numbers representing the dimensions shown in FIGS. 8 and 9 are in mm [mm]; the one shown in FIG. 8 is a conventional example, and the one shown in FIG. 9 is according to the present invention.

When trying to obtain a small multilayer ceramic capacitor with external planar dimensions of 1.5 x 0.8 mm, conventionally, as shown in Figure 8, gap margins have been set in terms of printing accuracy and cutting accuracy. It was manufactured with 0.25mm in mind. Therefore, the ratio of the area of the overlapping portion of the internal electrode 25 to the total area of the ceramic portion 24 was (1.0×0.3)/(1.5×0.8)=0.25, that is, only reached 25%. In addition, if we further take into account the overlapping deviation of the internal electrodes 7 as shown in FIG. 14, the above-mentioned ratio has actually reached only 22 to 23%.

On the other hand, in FIG. 9, there is only a gap margin of 0.05 mm, which corresponds to the thickness of the ceramic slurry 18, and the aforementioned ratio is (1.0 x 0.7) / (1.5 x 0.8) = 0.58. , it is possible to obtain 2.5 times the capacitance at once.

Furthermore, the variation in capacitance can be reduced from 30% in the past to 7 to 8% at 3CV.

Thus, according to this invention, especially recently,
Low rated voltage required for decoupling elements and bypass capacitors in ICs, LSIs, etc.
Ultra-small, large-capacity multilayer ceramic capacitors can be easily obtained.

[Brief explanation of drawings]

1 to 7 sequentially show the manufacturing process according to an embodiment of the present invention. FIG. 1 shows a ceramic green sheet 11, and FIG.
FIG. 3 shows a stacked state of ceramic green sheets 11, FIG. 3 shows a laminate 14, and FIG.
FIG. 5 shows the laminate block 16 with ceramic slurry 18 applied thereto, FIG. 6 shows the laminate chip 20, and FIG.
The figure shows a laminate chip 20 provided with external electrodes 22, 23. 8 and 9 show ceramic portions 24 and internal electrodes 25 in order to more specifically explain the effects of the present invention in comparison with the prior art.
It is a figure showing the relationship of the size with. Figure 10 shows
Ceramic green sheet used in conventional method 1
shows. FIGS. 11 and 12 are a vertical cross-sectional view and a cross-sectional view of a conventional multilayer ceramic capacitor. FIGS. 13 and 14 are cross-sectional views of a laminate chip 6 for explaining the conventional drawbacks. In the figure, 11 is a ceramic green sheet, 12 is a conductive film, 13 is a gap, 14 is a laminate, 15 is a cutting line (first direction), 16 is a laminate block, 17 is a first cut surface, and 18 is a Ceramic slurry, 19 is a cutting line (second direction), 20 is a laminate chip, 21 is a second cutting surface, 22, 23
is the external electrode.

Claims (1)

[Claims] 1. First and second external electrodes are formed on each end face of a laminate with internal electrodes facing each other interposed therebetween via a ceramic layer, and on each end face, an internal electrode is formed. A method for manufacturing a multilayer ceramic capacitor, in which a first group of capacitors are connected to a first external electrode, and a second group of capacitors are connected to a second external electrode, wherein A plurality of ceramic green sheets are prepared in which a plurality of conductive films are formed in a line in a first direction while being separated from each other through gaps, and the gap on one ceramic green sheet and the other ceramic green forming a laminate by laminating the plurality of ceramic green sheets so that the conductive films on the sheets are aligned in the lamination direction; and cutting the laminate along at least one cutting line facing in the first direction. Therefore, a laminate block is formed by cutting in the thickness direction, so that the conductive film is exposed on the first cut surface forming at least one side surface of the laminate block, and the first cut surface covered with a ceramic slurry, and the laminate block to which the ceramic slurry has been applied is placed at a position passing between the gaps by at least two cutting lines oriented in a second direction intersecting the first direction. A laminate chip is formed by cutting in the thickness direction, and a conductive film to be the internal electrode of the first group and the second exposing conductive films to become internal electrodes of each group, then firing the laminate chip, and applying the first and second external electrodes to both end faces of the fired laminate chip, respectively; A method for manufacturing a multilayer ceramic capacitor, characterized by comprising each step. 2. In the step of forming the laminate block, cutting the laminate along two cutting lines,
The laminated ceramic according to claim 1, wherein the conductive film is exposed on two opposing side surfaces of the laminate block, and the ceramic slurry is formed to cover the two side surfaces. How to manufacture capacitors. 3. The method of manufacturing a multilayer ceramic capacitor according to claim 1 or 2, wherein the ceramic slurry is made of the same ceramic material as the ceramic green sheet. 4. Claims 1 to 3, wherein one of the binders contained in the ceramic green sheet and the binder contained in the ceramic slurry is organic solvent-based and the other is water-soluble. A method for manufacturing a multilayer ceramic capacitor according to any one of the above.