JPH081876B2 - Manufacturing method of multilayer capacitor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer capacitor, and more particularly, to an improved method for forming a side margin region between an internal electrode and a dielectric side surface. To a method for manufacturing a multilayer capacitor.

[Conventional technology]

Multilayer capacitors are widely used in order to achieve miniaturization and large capacity of capacitors. Multilayer capacitors are
For example, as shown in FIGS. 2 (a) and 2 (b), prepare ceramic green sheets 3 and 4 to which internal electrode materials 1 and 2 are applied, alternately stack a plurality of sheets, and further, if necessary, the upper and lower layers. The ceramic green sheets on which the internal electrode material is not applied are laminated on the laminated body, the obtained laminated body is pressure-bonded in the thickness direction and then fired, and the external electrode is attached to the end surface of the sintered body where the internal electrode materials 1 and 2 are drawn out. It is obtained by forming.

By the way, the internal electrode materials 1 and 2 formed on the ceramic green sheets 3 and 4 are directed from the first end edges 3a and 4a of the respective ceramic green sheets 3 and 4 toward the second end edges 3b and 4b. It is printed so as to extend. In addition, each internal electrode material
1, 2 are the side edges 3c, 3d, 4 of the ceramic green sheets 3, 4
The width is printed such that the side margin area 5 of width x is left between c and 4d.

The side margin region 5 is provided by the internal electrode material.
This is to improve the adhesion between the ceramic green sheets located above and below the 1, 2 and prevent the internal electrode materials 1, 2 from being exposed on the side surface of the sintered body after sintering.

[Technical problem to be solved by the invention]

However, when the width x of the side margin region 5 is wide, the widths of the internal electrode materials 1 and 2 are naturally narrowed, which hinders an increase in capacity. Therefore, it is preferable that the width of the side margin region 5 is narrow in order to achieve further miniaturization and large capacity.

On the other hand, in mass production of the multilayer capacitor, as shown in FIGS. 3 (a) and 3 (b), relatively large mother ceramic green sheets 6 and 7 are prepared, and one main surface thereof has a plurality of mother inner electrode materials 8. After alternately laminating a plurality of products with the formation of 9 and 9, the laminated body is cut at a portion along the dashed lines A and B to obtain individual laminated dielectric raw chips, and the individual laminated dielectrics. Sintered bodies for individual multilayer capacitors are obtained by firing raw chips.

However, when the plurality of mother internal electrode materials 8 and 9 are printed, print displacement is unavoidable due to the temporal deformation of the printing screen. Also, when laminating the mother ceramic green sheets 6 and 7 on which the mother internal electrode materials 8 and 9 are formed,
Some stacking misalignment is unavoidable. As a result, in each dielectric raw chip after cutting, the internal electrode material may be exposed on the side surface of the dielectric raw chip. If the internal electrode material is exposed on the side surface of the dielectric raw chip, the obtained sintered body may have a poor withstand voltage or a short circuit between the internal electrodes.

Further, when the ceramic green sheets are misaligned as described above, the overlapping area of the internal electrodes is also reduced, and the obtained capacitance may be lower than the designed capacitance.

Furthermore, when the internal electrode reaches the vicinity of the side surface of the sintered body even before it is not exposed, that is, in FIG.
When the side margin region 5 of (b) is narrow, this also causes a breakdown voltage failure or peeling of the layer after sintering due to insufficient adhesion strength between the upper and lower ceramic layers.

As shown in FIG. 4 in a sectional view taken along line IV-IV in FIG. 2A, when the internal electrode material 1 having a width narrower than that of the ceramic green sheet 3 is printed, the internal electrode material 1 In the side edge portions 1a, 1a, the thickness of the internal electrode material 1 tends to be thicker than other portions. As a result, there is also a problem that layer peeling easily occurs between the ceramic layers at the side edge portions of the internal electrodes after lamination and sintering.

Although it is preferable that the width x of the side margin region 5 is narrow for various reasons as described above, the width x needs to be increased more than necessary in the conventional method for manufacturing a multilayer capacitor. Therefore, it has been an obstacle to miniaturization and large capacity. In addition, variations in capacity and layer peeling due to stacking deviation cannot be ignored.

Therefore, the object of the present invention is to achieve further miniaturization and large capacity as compared with the conventional multilayer capacitor, less variation in the capacitance value, and inexpensive that can be manufactured by a relatively simple process. Another object of the present invention is to provide a method of manufacturing a multilayer capacitor.

[Means for solving technical problems]

According to the present invention, a plurality of dielectric ceramic layers are laminated with an internal electrode interposed therebetween, and the width of the internal electrode is narrower than that of the dielectric ceramic layer, whereby the side electrode is laterally disposed to the internal electrode. A method of manufacturing a multilayer capacitor provided with a margin region, characterized by comprising at least the following steps.

That is, a first internal electrode material made of a material that is difficult to etch is formed near the edge along the one edge so that the first internal electrode material is connected to the one internal electrode material and faces the one edge. A plurality of ceramic green sheets provided with a second internal electrode material made of an easily-etchable material so as to extend to the edge side so as to extend over the entire width, and the edge on the side provided with the first internal electrode material has a thickness direction. In the step of obtaining a laminated type dielectric raw chip which is laminated so as to be alternately located on the opposite end face in, and sintering the ceramic type green sheet by firing the laminated type dielectric raw chip, A step of baking a second inner electrode material to form a plurality of inner electrodes composed of first and second inner electrode portions; and a chemical for selectively etching the second inner electrode portion of the sintered body. Etching with the second internal A side margin region by removing at least a portion of the portion exposed on the side surface of the sintered body and the vicinity thereof, and an external electrode is formed on a pair of end faces of the internal electrode of the sintered body. And a step of forming.

[Action]

In the manufacturing method of the present invention, after obtaining a laminated type sintered body,
Since the side margin region is formed by etching, the width of the side margin region can be accurately formed by controlling the etching state.
Therefore, it is possible to accurately control the overlapping area of the internal electrodes and to reduce the capacitance variation.

In addition, since a dielectric raw chip with an internal electrode material having the same width as the dielectric ceramic layer interposed therebetween is used,
When stacking to obtain a raw chip, it is not necessary to unnecessarily widen the width of the side margin region in consideration of stacking deviation. Therefore, it is possible to obtain a multilayer capacitor having a smaller size and a larger capacity.

Moreover, since the tolerance for the above-mentioned stacking deviation is large, the stacking work prior to the sintering can be easily performed.

Furthermore, since the first internal electrode portion is made of a material that is difficult to etch, only the portion of the second internal electrode portion exposed on the side surface of the sintered body is immersed in the etching agent. Since it can be reliably etched, the above etching can be easily performed by immersing the entire sintered body in an etching agent.

[Explanation of Example]

Hereinafter, a manufacturing method according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 5 is an exploded perspective view for explaining a mother ceramic green sheet mainly made of a dielectric material used in the manufacturing method of the present embodiment and the coating shape of the internal electrode material formed on the upper surface thereof.

On the upper surface of the rectangular mother ceramic green sheet 11, the first internal electrode material 12a is printed in a strip shape along the one edge 11a. The first internal electrode material 12b is also printed in parallel with the first end edge 11a at a predetermined distance from the first internal electrode material 12a. Then, in the remaining area, second internal electrode materials 13a and 13b having a width wider than that of the first and second internal electrode materials 12a and 12b are printed.

Similarly, the first inner electrode materials 15a and 15b and the second inner electrode materials 16a and 16b are also printed on the upper surface of the ceramic green sheet 14. As is apparent from FIG. 5, the print pattern of the internal electrode material printed on the upper surface of the mother ceramic green sheet 14 was obtained by reversing the print pattern of the internal electrode material formed on the upper surface of the ceramic green sheet 11 by 180 degrees. Equivalent to a thing.

The above-mentioned ceramic green sheets 11 and 14 are obtained by molding a ceramic slurry mainly composed of dielectric ceramics into the shape shown in the drawing by, for example, the doctor blade method.

The internal electrode materials 12a to 13b and 15a to 16b are made of a conductive paste obtained by kneading a conductive material with an organic binder. As the conductive material, Ni, Cu, Ag or Ag-Pd
Various metal materials such as can be used.

The first internal electrode materials 12a, 12b, 15a, 15b and the second internal electrode materials 13a, 13b, 16a, 16b are made of different materials. That is, the first internal electrode materials 12a, 12b, 15a, 15
b is made of a material that is difficult to be etched by an etching agent used in the etching step described later, while the second internal electrode materials 13a, 13b, 16a, 16b are easily etched by the etching agent. It is composed of materials.

The ceramic green sheets 11 and 14 shown in FIG.
Alternately stacking a plurality of sheets, and further stacking ceramic green sheets with no internal electrode material provided on the top or bottom as necessary, and cutting at the portions corresponding to the one-dot chain lines A and B in FIG. Thus, the laminated dielectric raw chip 17 shown in FIG. 6 can be obtained.

In the dielectric raw chip 17, a ceramic green sheet 18 to which an internal electrode material is not applied is laminated on the uppermost part. In addition, for easy understanding, the dielectric raw chip 17
The internal electrode materials therein will be described with the same reference numerals as the internal electrode materials shown in FIG.

First and second side surfaces 17a of the dielectric raw chip 17 facing each other,
17b respectively include the first inner electrode materials 12a, 12a, 12a and
15a, 15a, 15a are exposed. Further, the second internal electrode materials 13a, 16a arranged so as to be connected to the first internal electrode materials 12a, 15a have the same width as the ceramic green sheet, so that the third, third 4 side 17c,
Exposed to 17d.

Furthermore, the end of the second inner electrode material 13a, 16a opposite to the side on which the first inner electrode material 12a, 15a is provided is also exposed on the second or first side surface 17b or 17a. .

As described above, in obtaining the dielectric raw chip 17, by laminating a plurality of ceramic green sheets 11 and 14 shown in FIG. 5 and cutting the green green sheets 11 and 14 at a portion corresponding to the one-dot chain lines A and B, can get. Therefore, unlike the conventional example of FIG. 2, it is not necessary to cut the laminated body in consideration of the width x of the side margin region 5 in advance, so that the dielectric raw chip 17 can be obtained extremely easily and stably.

The mother ceramic green sheet 1 shown in FIG.
It is not always necessary to manufacture a large number of dielectric raw chips 17 at one time by using 1,14. That is, a rectangular ceramic green sheet having a size necessary for stacking the individual dielectric raw chips 17 is printed with each internal electrode material having the same width as the ceramic green sheet, and the dielectric green sheets are stacked. Chip 17 may be prepared.

Next, the chip in dielectric 17 is pressed by the thickness method. This pressing is performed to increase the density of the dielectric green chips 17 and to improve the adhesion between the ceramic green sheets before sintering.

In the conventional method described with reference to FIG. 2, the internal electrode materials 1 and 2 were printed in a smaller area than the ceramic green sheets 3 and 4 during the press prior to this sintering. The press pressures tended to vary in the three types of regions, namely, the overlapping region, the region where only the internal electrode materials 1 and 2 exist, and the region where the internal electrode materials 1 and 2 do not exist at all. That is, a high pressing pressure is applied only to the area where the internal electrode materials 1 and 2 are overlapped with each other, and sufficient pressing pressure is not applied to other areas, which causes layer peeling after sintering.

On the other hand, in the manufacturing method of this embodiment, as shown in FIGS. 6 and 7 (a) and (b), the dielectric raw chip is used.
The internal electrode materials are overlapped with each other in the entire area when 17 is viewed in plan. Therefore, since the entire region is pressed by a sufficiently large pressing pressure, it is possible to obtain a dense sintered body in which layer peeling is unlikely to occur due to firing described later.

Further, as shown in FIG. 4, in the conventional manufacturing method,
The side edge portions 1a, 1b of the internal electrode material tend to be thicker than other portions, and therefore, when a plurality of ceramic green sheets are laminated, the thickness of the internal electrode material is not uniform in the width direction. Layer peeling was likely to occur later.

On the other hand, in this embodiment, as shown in the cross-sectional view corresponding to FIG. 8, the internal electrode material 13a is formed to have a width extending to the entire width of the ceramic green sheet 11 '. The thickness is uniform in the width direction. Therefore, it is possible to effectively prevent the occurrence of delamination due to the nonuniformity of the thickness of the internal electrode material in the width direction. The ceramic green sheet 11 'is shown by extracting one layer of the ceramic green sheet layer in the raw chip 17.

Next, the pressed dielectric green chip 17 is fired to integrally fire the internal electrode material and the ceramic green sheet.
In addition, in the following description, each internal electrode portion baked by firing is described with the same reference numeral as each internal electrode material described above.

As shown in FIG. 9, a plurality of internal electrodes 21 and 22 are arranged in the obtained sintered body 20 so as to overlap each other with a dielectric ceramic layer in the thickness direction. And
In the internal electrode 21, the first internal electrode portion 12a has the first side surface 20a.
Is exposed to the inner electrode 22, and the first inner electrode portion is
15a is exposed on the second side surface 20b. Also, internal electrodes
In 21, the second internal electrode portion 13a has side surfaces 20c and 20d,
It is exposed on the second side surface 20b. Similarly, the internal electrode 22
Then, the second inner electrode portion 16a is exposed to the side surfaces 20c and 20d and the first side surface 20a.

That is, in the thickness direction of the sintered body 20, the plurality of internal electrodes 21 and 22 are arranged so that the first internal electrode portions 12a and 15a are alternately exposed to the first and second side surfaces 20a and 20b. Has been done.

Next, the sintered body 25 is immersed in a chemical that selectively etches the second internal electrode portions 13a and 16a, and etching is performed. The state after etching is shown in a perspective view in FIG. 10 and a plan sectional view in FIG.

As is clear from FIG. 1, the second
The portions of the internal electrode portion 13a exposed on the side surfaces 20c, 20d, 20b of the sintered body and the vicinity thereof are removed. That is, by this etching, the tip margin region 25 is formed between the side margin regions 23 and 24 and the side face 20b on the side of the second internal electrode portion 13a. In this case, the first internal electrode portion 12a is not etched by etching.

That is, a chemical that selectively etches only the second internal electrode portions 13a and 16a is used for the etching. Further, as described above, the internal electrode material for the second internal electrode portions 13a and 16a is made of the easily-etchable material,
The electrode paste forming the internal electrode portions 12a and 15a is made of a material that is difficult to etch.

Although FIG. 1 shows only the portion where the internal electrode 21 is formed, the side margin area and the tip margin area between the side surface 20a are also formed in the portion where the internal electrode 22 is formed. It

The widths of the side margin regions 23 and 24 and the tip margin region 25 can be accurately controlled by adjusting the etching conditions, that is, the type and concentration of the chemical, the etching time, and the like. Therefore, the overlapping area of the internal electrodes can be set accurately.

In addition, since the side margin regions 23 and 24 can be formed regardless of the lamination process up to sintering, etc., the side margin having a width sufficient and sufficient to prevent short circuit between internal electrodes in the completed multilayer capacitor. The regions 23 and 24 may be formed. That is, a side margin region having a narrower width than that of the conventional method can be formed, so that a small-sized and large-capacity multilayer capacitor can be realized.

Next, the first and second side surfaces 20a of the sintered body 20 shown in FIG.
A pair of external electrodes 26, 27 are formed on 20b as shown in FIG. The external electrodes 26, 27 can be formed by applying and baking a conductive paste, but other conductive film forming methods such as plating and sputtering may be appropriately used.

Note that, as shown in FIG. 12 in a sectional view taken along line XII-XII in FIG. 10, after the etching, the side margin region is
The void 28 is formed along with the formation of 23, 24 and the tip margin region. When the size of the void 28 is not negligible, a sealing material 29 may be filled as shown in FIG. As the sealing material 29, it is preferable to use a synthetic resin having excellent insulation and moisture resistance.

Further, the filling of the sealing material 29 is preferably performed in the state shown in FIG. By filling the sealing material 29 before the formation of the external electrodes 26, 27, the sealing material can be filled also in the tip margin region, so that the internal electrode 21 or 22 and the other internal electrode can be filled.
This is because it is possible to reliably prevent a short circuit with an external electrode connected to 22 or 21.

FIGS. 14 (a) and 14 (b) are plan views for explaining a ceramic green sheet that can be used in another embodiment of the present invention and a printed shape of an external electrode paste formed thereon. As shown in FIG. 14 (a), a first internal electrode material 32 made of a hard-to-etch material is printed on a rectangular ceramic green sheet 31 along one edge 31a, and the first internal electrode material 32 is printed. An easily-etchable internal electrode material 33 is printed so as to be continuous with the electrode material 32. here,
The length of the second internal electrode material 33 does not reach the other end edge 31b of the ceramic green sheet 31. Similarly,
As shown in Figure 14 (b), a ceramic green sheet
A material is prepared by printing the first and second internal electrode materials 35, 36 on 34, with the position reversed from that on the ceramic green sheet 31.

A plurality of the ceramic green sheets 31 and 34 may be laminated, and if necessary, ceramic green sheets having no electrode paste printed on the uppermost and lowermost portions may be laminated to obtain a dielectric raw chip. In this case, since the second inner electrode materials 33, 36 are formed so as not to reach the edges 31b, 34b, etching should be performed only on the side edge portions of the second inner electrode materials 33, 36. Good. That is, the leading edge margin region in the above-described embodiment is formed by providing a region where the internal electrode material is not printed.

Further, instead of the mother ceramic green sheets shown in FIG. 5, a plurality of mother ceramic green sheets 37, 38 shown in FIGS. 15 (a) and 15 (b) may be alternately laminated. First
In the example of FIG. 5 (a), after stacking, cutting is performed along the alternate long and short dash lines A and B of FIGS. 15 (a) and 15 (b). However, the printed shape of the internal electrode material formed on the upper surface of the ceramic green sheet 14 shown in FIG. 5 is equivalent to the inverted printed shape of the internal electrode material formed on the upper surface of the ceramic green sheet 11. For this reason, only one type of printed shape was required, but in the example of FIG. 15, two types of ceramic green sheets 37, 38 in which the first and second internal electrode materials are printed in different printed shapes must be prepared. I have to.

〔The invention's effect〕

As described above, in the manufacturing method of the present invention, the side margin region on the side of the internal electrode is formed by etching the side edge portion of the second internal electrode portion exposed on the side surface of the sintered body and the vicinity thereof. It is formed. Therefore, in the laminating step performed to obtain the laminated type sintered body, the side margin area having the minimum necessary width is accurately formed without considering the laminating deviation of the ceramic green sheets and the printing deviation of the conductive paste for internal electrodes. can do. Therefore, it is possible to obtain a small-sized and large-capacity multilayer capacitor with small variation in capacitance value.

Further, in the laminated type sintered body, the width of the second internal electrode portion is the same as the width of the dielectric ceramic layer, so that the allowable positioning range of the ceramic green sheet is widened during the lamination prior to sintering, The laminating operation can be performed relatively easily. Furthermore, when forming the first and second internal electrode portions, the conductive paste is printed in the same width as the ceramic green sheet, so the number of types of electrode print patterns can be reduced. Therefore, the cost of the multilayer capacitor can be reduced by simplifying the work process.

Further, in the above-mentioned integrally fired sintered body, since the second internal electrode portion and the first internal electrode portion are exposed on the side surface, the internal electrode portion exposed on the side surface during sintering is inside the ceramics. It also serves as a heat transfer medium that promotes sintering, and has an effect that sintering can be favorably performed in a short time.

[Brief description of drawings]

FIG. 1 is a plan sectional view showing a state in which a side margin region is formed by etching in a manufacturing method according to an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are used for manufacturing a conventional multilayer capacitor. 3A and 3B are plan views showing the printed shapes of the ceramic green sheet and the internal electrode material formed thereon, and FIGS. 3A and 3B are mother ceramic green sheets and mother internal electrodes used in mass production of conventional multilayer capacitors. Each plan view for explaining the print shape of the material,
FIG. 4 is a cross-sectional view for explaining a problem in the conventional multilayer capacitor, and FIG. 5 shows a mother ceramic green sheet used in one embodiment of the present invention and a printing shape of an internal electrode material formed thereon. FIG. 6 is a perspective view for explaining, and FIG. 6 is a perspective view showing a laminated dielectric raw chip, FIG. 7 (a).
And (b) are side and plan sectional views of the dielectric raw chip of FIG. 6, and FIG. 8 is a sectional view for explaining the shape of the side edge of the second internal electrode material in the embodiment of the present invention. Figure, No. 9
FIG. 10 is a perspective view showing a laminated type sintered body, FIG. 10 is a perspective view showing the sintered body after etching, FIG. 11 is a perspective view showing a state in which an external electrode is formed, and FIG. 12 is FIG. XII-XII line enlarged cross-sectional view, FIG. 13 is a cross-sectional view showing a state in which the gap is filled with a sealing material, and FIGS. 14A and 14B are for explaining another embodiment of the present invention. FIGS. 15 (a) and 15 (b) are plan views for explaining still another example of the printed shapes of the ceramic green sheet and the internal electrode material that can be used in the present invention. In the figure, 11 and 14 are ceramic green sheets, 12a and 1
2b, 15a, 15b are first internal electrode parts (first internal electrode material),
13a, 13b, 16a, 16b are second internal electrode parts (second internal electrode material), 20 is a sintered body, 20a, 20b are first and second side surfaces, 21 and 22 are internal electrodes, 23, 24 is a side margin region, 25 is a tip margin region, and 26 and 27 are external electrodes.

Claims (1)

[Claims] 1. A plurality of dielectric ceramic layers are laminated with an internal electrode interposed therebetween, and the width of the internal electrode is narrower than the width of the dielectric ceramic layer, whereby the side of the internal electrode is formed. In the method for manufacturing a multilayer capacitor in which a side margin region is formed on one side, a first internal electrode material made of a hardly-etchable material is formed on the one internal electrode material in the vicinity of the one edge so that The plurality of ceramic green sheets provided with the second internal electrode material made of the easily-etchable material so as to extend over the entire width so as to be connected and extend to the edge side facing the one edge is A step of obtaining a laminated-type dielectric raw chip that is laminated so that the end edges on the side to which the internal electrode material is applied are alternately located on the opposite end faces in the thickness direction; Firing Sintering the ceramic green sheet and baking the first and second internal electrode materials to form a plurality of internal electrodes composed of the first and second internal electrode portions; and A side margin region is formed by etching the second internal electrode portion with a chemical that selectively etches, and removing at least a portion of the second internal electrode portion exposed on the side surface of the sintered body and its vicinity. A method of manufacturing a multilayer capacitor, comprising: a step; and a step of forming external electrodes on a pair of end faces of the sintered body from which the internal electrodes are drawn out.