JPH0831397B2 - 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]

BACKGROUND ART Multilayer capacitors are widely used in order to achieve miniaturization and large capacity of capacitors. For the multilayer capacitor, for example, as shown in FIGS. 2 (a) and 2 (b), ceramic green sheets 3 and 4 coated with internal electrode materials 1 and 2 made of a dielectric paste are prepared, and a plurality of them are alternately arranged. Laminated, the resulting laminate is pressure-bonded in the thickness direction and then fired,
It is obtained by forming external electrodes on the side surfaces of the sintered bodies from which the internal electrode materials 1 and 2 are drawn.

Incidentally, the internal electrode materials 1 and 2 formed on the ceramic green sheets 3 and 4 move from the first edges 3a and 4a of the ceramic green sheets 3 and 4 toward the second edges 3b and 4b. It is formed to extend. Also, each internal electrode material
1, 2 are the side edges 3c, 3d, 4 of the ceramic green sheets 3, 4
It is formed in such a width that the side margin region 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 ceramic green sheets 1 and 2, and to prevent the internal electrode materials 1 and 2 from being exposed to the side surfaces of the sintered body after sintering. Therefore,
Conventionally, in multilayer capacitors, internal electrode materials 1, 2
It was indispensable to form the side margin region 5 having the width x on the side of.

[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, smaller
To achieve a large capacity, the width x of the side margin region 5 is preferably small.

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 those having formed 9, the laminated body is cut along the alternate long and short dashed lines A and B to obtain individual laminated bodies, and the individual laminated bodies are fired to obtain the individual laminated bodies. Manufactures multilayer capacitors.

However, when laminating the mother ceramic green sheets 6, 7 on which a plurality of mother internal electrode materials 8, 9 are formed, some lamination displacement has to occur, and as a result, after cutting, in each laminate The internal electrode material may be exposed on the side surface of the laminate. If the internal electrode material is exposed on the side surface of the laminated body, a withstand voltage defect or a short circuit between the internal electrode materials occurs.

Moreover, when the internal electrode material reaches the vicinity of the side surface of the sintered body even before it is not exposed, that is, in FIG. 2 (a),
In the case where the side margin region 5 in (b) is small, the adhesion strength between the upper and lower ceramic layers is not sufficient, which causes peeling after sintering.

Further, when the stacking deviation occurs, the overlapping area of the internal electrode materials also becomes small, and the capacitance value may be lower than the design capacitance.

For the above reasons, although it is preferable that the width x of the side margin region 5 is narrow, it is necessary to increase the width x more than necessary, which hinders miniaturization and large capacity. In addition, variations in capacitance and delamination tend to occur due to stacking deviation.

Therefore, an object of the present invention is to provide an inexpensive multilayer capacitor that can be made smaller and have a larger capacity than conventional multilayer capacitors, has less variation in capacitance value, and can be manufactured by a relatively simple process. It is to provide a manufacturing method of.

[Means for solving technical problems]

The present invention provides a laminated dielectric in which a plurality of dielectric layers are laminated with an internal electrode interposed therebetween, and the width of the internal electrode is the same as the width of the dielectric layer. On the side surface of the laminated dielectric in which the side edge of the electrode is exposed,
A method for manufacturing a multilayer capacitor, which comprises a step of forming a side margin region on a side of the internal electrode by etching an exposed side edge portion of the internal electrode,
It is characterized by comprising the following steps.

That is, the method is characterized by further including a step of heating or neutralizing the remaining etching liquid in the space where the side margin region is formed so as not to act as an etching agent.

[Action]

In the manufacturing method of the present invention, the side margin region is formed by etching after obtaining the laminated dielectric. Therefore, the width of the side margin region can be accurately formed, the overlapping area of the internal electrodes can be accurately controlled, and the capacitance variation can be reduced.

Also, an internal electrode having the same width as the dielectric layer is laminated,
Since the side margin region is formed by etching after stacking, 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 larger-sized and large-capacity multilayer capacitor.

Moreover, since the laminated body in which the internal electrodes having the same width as the laminated body layer are laminated is used, the tolerance for the laminated layer deviation is large, and therefore the laminated work can be easily performed.
In addition, it is possible to obtain a multilayer capacitor having a side margin region having a minimum necessary width.

Further, the etching solution remaining after the etching is removed by heating or neutralized to stop the progress of the etching action. Therefore, corrosion of the internal electrodes due to the residual etching solution is also prevented.

[Explanation of Example]

A manufacturing method according to one embodiment of the present invention will be described with reference to FIGS. This embodiment is applied to a method for manufacturing a multilayer capacitor using dielectric ceramics.

FIG. 4 is a perspective view for explaining a ceramic green sheet as a dielectric layer used in the manufacture of the present embodiment and internal electrode materials formed thereon. On the upper surfaces of the rectangular ceramic green sheets 11, 12, internal electrode members 13, 14 are formed in a film shape, respectively.

The ceramic green sheets 11 and 12 are obtained by forming a ceramic slurry mainly composed of a dielectric ceramic into the shape shown in the figure. The internal electrode materials 13 and 14 are made of Ni
Alternatively, it is configured by applying a conductive paste mainly composed of a dielectric material such as Cu. As a material forming the internal electrode material, various metal materials such as Ag or Ag-Pd can be used in addition to Ni and Cu. However, it is necessary to use a material that can be etched by an appropriate etchant in the etching described later.

The internal electrode material 13 is a rectangular ceramic green sheet 11
Is formed so as to extend from one end 11a toward the opposite end 11b and not to reach the end 11b. The width of the internal electrode material 13 is the same as the width of the ceramic green sheet 11. That is, the internal electrode material 13 is formed over the entire width between the side edges 11c and 11d of the ceramic green sheet 11.

The internal electrode material 14 is configured similarly to the internal electrode material 13. However, the ceramic green sheets from which the internal electrode materials 14 are drawn out such that the internal electrode materials 13 and 14 are drawn out to the opposite side surfaces of the laminate when the ceramic green sheets 11 and 12 are stacked. 12 one edge 12
The a is located on the opposite side of the one end edge 11a of the ceramic green sheet 11.

The ceramic green sheets 11 and 12 shown in FIG.
By alternately laminating a plurality of sheets, a laminate shown in FIG. 5 is obtained.
You can get 15. In the laminate 15, three first and second ceramic green sheets 11 and 12 are alternately laminated three by three, and further, a ceramic having no internal electrode material provided on the uppermost part (and also on the lowermost part as necessary). Green sheet
16 are laminated as needed.

Here, one of the three internal electrodes 13a to 13c is
On the first side surface 15a of the second inner electrode material 14a-14c
Side 15b. In addition, each internal electrode material 13a ~
13c, 14a to 14c are the third and fourth side surfaces 15c,
It is also exposed on 15d.

In obtaining the laminated body 15, it is preferable to use the mother ceramic green sheet shown in FIG. 6 in the actual mass production process. That is, the mother internal electrode materials 18a and 18b extending from one end edge 17a to the other end edge 17b are formed on a relatively large rectangular mother ceramic green sheet 17 with a predetermined distance therebetween. Similarly, on the ceramic green sheet 19 as the mother dielectric sheet, the mother internal electrode materials 20a and 20b are formed from the one end edge 19a of the ceramic green sheet 19 to the other end edge 19b.

Then, a plurality of ceramic green sheets 17 and 19 are alternately stacked in the illustrated direction, and cut at a portion corresponding to a portion along the dashed lines A and B, thereby obtaining the same as the stacked body 15 shown in FIG. Many structures can be obtained.

In this way, by using the mother ceramic green sheets 17 and 19, the laminate 15 shown in FIG. 5 can be efficiently mass-produced. Moreover, in the laminate 15 shown in FIG. 5, the internal electrode members 13a to 13c and 14a to 14c are formed to have a width that is also exposed to the third and fourth side surfaces 15c and 15d. Therefore,
When the ceramic green sheets 17 and 19 of FIG. 6 are laminated, even if a slight deviation occurs in the direction of arrow C in FIG. 6, in the obtained laminated type dielectric 15, the internal electrode material is formed in the direction of arrow C. There is no overlap deviation of. Therefore, even if some inevitable lamination deviation occurs when laminating the mother ceramic green sheets 17 and 19, the laminated body 15 with little variation in the electrode overlapping area can be stably obtained.

Further, in the conventional example shown in FIG. 2, when a conductive paste for forming the internal electrode material 1 is applied, due to the surface tension of the paste, as shown in FIG. Ridges 21a and 21b were formed on the side edges. Therefore, when a plurality of ceramic green sheets are laminated, the thickness of the internal electrode material is not uniform, which is one of the causes of layer peeling after sintering.

On the other hand, in this embodiment, as shown in the cross-sectional view corresponding to FIG. 7 (b), the internal electrode material 13 reaches the entire width between the side edges 11c and 11d of the ceramic green sheet 11. Since it is formed, the thickness of the internal electrode material 13 is made uniform in the width direction. Therefore, it is possible to effectively prevent the occurrence of delamination due to the uneven thickness of the internal electrode material.

Returning to FIG. 5, prior to firing, the laminated body 15 is pressed in the thickness direction so that the ceramic green sheets are brought into close contact with each other. In this case, in the laminated body 15 of the present embodiment, the internal electrode materials 13a to 13c, 14a to 14c are formed so as to extend over the entire width between the third and fourth side surfaces 15c, 15d, and therefore, as shown in FIG. VIII
As shown in the schematic cross-sectional view of FIG. 8 (b) along the line VIII, pressure bonding can be performed so that the thickness becomes uniform in the Y direction of FIG.

On the other hand, in the conventional example using the ceramic green sheet shown in FIG. 2, since the side margin region 5 is formed in advance, as shown in FIG. The thickness is reduced in the portion where the margin area is formed, and the difference between the thickness of the laminated body in the portion where the internal electrode materials 1 and 2 are formed and the thickness of the side area where the side margin area is formed. Therefore, delamination was likely to occur on the side surface of the obtained sintered body.
Therefore, in the laminate of this embodiment, the occurrence of delamination due to such a reason can be effectively prevented.

Next, the laminated body 15 of FIG. 5 pressed in the laminating direction is fired to obtain a laminated dielectric sintered body. Further, as shown in FIG. 9, the first and second side surfaces of the obtained sintered body 25 are covered with resist materials 26a and 26b. This resist material 26a, 2
6b is made of a material that is not attacked by an etchant used for etching described later, and a synthetic resin such as an epoxy resin can be used as an example.

In the sintered body 25, the above-described internal electrode material is baked during firing of the ceramics, so that the internal electrode 13a
13c and 14a to 14c are formed. Note that the reference numbers of the internal electrodes will be described with the same reference numbers as those of the above-described internal electrode materials.

Each of the internal electrodes 13a to 13c, 14a to 14c is a resist material 26a, 26b.
, Except for the portions covered with, that is, the third and fourth side surfaces 25c and 25d of the sintered body 25.

Next, the third and fourth side surfaces 25c and 25d of the sintered body 25 are etched with an etchant capable of etching the material constituting the internal electrodes 13a to 13c and 14a to 14c. As the etchant, for example, a strong acid such as nitric acid can be used, but when a metal material other than Cu and Ni is used as the internal electrode material, an appropriate etchant capable of etching such metal material is used. Used.

The state after the etching is shown in a plan sectional view in FIG. First
As is apparent from FIG. 10, in the sintered body 25, the two sides 32, 33 adjacent to the end edge 31 where the internal electrode 13a is pulled out to the first side surface 25a of the sintered body 25 are Side margin area 3
It is retracted inward from the third and fourth side faces 25c, 25d so as to form 4,35 between the third and fourth side faces 25c, 25d. This is because both side edges of the internal electrode 13a are etched by etching, and
4,35 is formed.

Side margin regions are similarly formed in other internal electrodes 13b, 13c, 14a to 14c.

Further, as is apparent from FIG. 11, a gap 34 is formed by etching in a portion where the side margin region is formed.
a and 35a are formed.

After the etching, the sintered body 25 is washed with water or the like to remove the etchant. However, it may be difficult to completely remove the residual etchant, particularly the etchant remaining in the voids 34a and 35a, only by washing with water. Therefore, in this embodiment, the sintered body 25 is then placed in a heating atmosphere to scatter and remove the residual etchant.

In addition, the above-mentioned heating may use heat given in a step of baking an external electrode described later. In that case, the removal of the residual etchant and the baking of the external electrode can be performed in one step.

Further, the removal of the residual etchant is to prevent the internal electrode from being corroded by the residual etchant. Therefore,
A method other than heating may be used as long as the etching action can be removed. For example, if the etchant is a strong acid, the residual etchant may be neutralized by dipping in an alkaline solution.

Following the removal of the residual etchant, the resist material 26
Remove a and 26b. The resist materials 26a and 26b can be removed by mechanical polishing, a method using a chemical, or the like.

In this embodiment, since the side margin regions 34 and 35 are formed by etching, the third and fourth side surfaces of the sintered body 25 are formed.
A side margin region having an accurate width can be formed inward from 25c and 25d. Moreover, the side margin regions 34 and 35 are formed after the ceramic green sheet and the internal electrode material are laminated to obtain a laminated body.
It is not necessary to form a side margin region having an extra width in consideration of stacking deviation and the like. That is, the side margin regions 34 and 35 can be formed with a width narrower than that of the conventional example. Therefore, it is understood that a small-sized and large-capacity multilayer capacitor can be realized.

Further, even if the internal electrode material hangs from the exposed portion of the side surface 6 of the laminate, the dripping internal electrode material is surely removed during etching.

Finally, on the surface from which the resist materials 26a and 26b are removed, for example, A
As shown in FIGS. 1 and 12, by applying a dielectric paste mainly composed of g and baking it, a pair of external electrodes
36,37 are formed. The external electrodes 36 are internal electrodes 13a to 13c.
In addition, the external electrode 37 is electrically connected to the internal electrodes 14a to 14c.

Preferably, after forming the external electrodes 36, 37, the sintered body 2
The third and fourth side surfaces 25c, 25d of 5 may be subjected to an oxidation treatment.
The oxidation treatment is achieved, for example, by heating the multilayer capacitor of FIG. 12 in an oxidation atmosphere for a predetermined time. In the present embodiment, the third and fourth side surfaces 25c of the sintered body 25,
At 25d, relatively narrow side margin areas 34,35
Since the side edges of the internal electrodes 13a to 13c and 14a to 14c are disposed through the side margin regions formed by etching, the side edges of the internal electrodes are oxidized by an oxidizing atmosphere. Therefore, an oxide film is formed on the inner electrode side edge. The formation of this oxide film effectively enhances the adhesion strength between the internal electrodes and the ceramics. This is because a chemical bond is generated between the dielectric ceramic and the internal electrode when it is oxidized.

Therefore, it is possible to further improve the adhesion between the internal electrodes 13a to 13c, 14a to 14c and the dielectric ceramics by performing an oxidation treatment such as a copse.

The oxidation treatment may be performed at any stage as long as the side margin regions 34 and 35 are formed by etching. That is, the oxidation treatment may be performed prior to the formation of the external electrodes 36, 37.

Further, preferably, by injecting a synthetic resin such as an epoxy resin under pressure into the voids 34a, 35a of FIG. 11, a sintered body is obtained.
25 sides 25c, 25d can be sealed. In addition, as a sealing material, arbitrary materials, such as rubber | gum, other than a synthetic resin, may be used.

The sealing treatment may be performed after the external electrode is formed, or may be performed before the external electrode is formed.

Furthermore, in the above-described embodiment, the pair of external electrodes 36 and 37 are formed after the etching is performed, but the external electrodes may be formed before the etching.

In the above embodiment, since the internal electrodes 13a to 13c and 14a to 14c are made of inexpensive Ni or Cu, the electrode cost can be reduced. In addition, since the mother ceramic green sheets can be laminated without much concern for lamination displacement and the like, the manufacturing process is simplified, and the mass production cost of the multilayer capacitor can be effectively reduced.

Incidentally, preferably, the side surface of the sintered body on which the external electrodes 36, 37 are formed is coated with a dielectric paste mainly composed of Ni, and then the external electrodes 36, 37 are formed,
The reliability of the electrical connection between the internal electrode and the external electrode can be improved. Further, instead of Ni, another conductive material layer may be applied to the first and second side surfaces 25a and 25b of the sintered body 25. In this case, if a material which is not etched by the etchant is used, The functions of the resist materials 26a and 26b described above can also be provided. That is, the resist materials 26a and 26b can be constituted by the base electrode for forming the external electrodes. In this case,
No removal of resist material is required.

In the above-described embodiment, the side edges of the internal electrodes are etched by using a chemical agent such as nitric acid as an etchant.
The actual etching can be performed by immersing the sintered body in an etchant, or by storing the etchant in a rotating barrel and putting the sintered body in the barrel and rotating the barrel.

In the embodiments described above, ceramic green sheets are used as dielectric sheets. However, the present invention is limited to a multilayer ceramic capacitor formed by laminating a plurality of ceramic green sheets and integrally firing together with internal electrode materials. is not. That is, a dielectric resin film can be used as the dielectric sheet, and the present invention can be applied to so-called laminated film capacitors.

Further, the present invention can be applied to a winding type capacitor formed by winding a long ceramic green sheet or a resin film together with an internal electrode formed on the main surface thereof, and therefore, this type of winding It should be pointed out that the type capacitors are also included in the multilayer capacitor according to the present invention.

〔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 two sides of the internal electrode that are adjacent to the edge of the internal electrode that is pulled out. That is, since the side margin region is formed by etching after stacking, it is possible to accurately form the side margin region having the minimum necessary width without considering stacking deviation and the like. Therefore, small
It is possible to obtain a multilayer capacitor having a large capacity and less variation in capacity value.

In addition, since the side margin region is formed by etching after lamination, not only the small-sized and large-capacity laminated capacitor as described above can be obtained, but also the positioning allowable range is widened when the dielectric sheets are laminated, The laminating operation can be performed relatively easily. Further, since the internal electrode forming electrode pattern is formed to have the same width as the dielectric layer, the number of types of electrode patterns can be reduced. Therefore, by simplifying the work process,
It is possible to reduce the cost of the multilayer capacitor.

Furthermore, by heating or neutralizing the residual etching solution,
Since it is removed or rendered ineffective, there is no risk of corrosion of the internal electrodes due to the residual etching solution.

Further, in the case of using a ceramic as a dielectric and sintering before processing such as etching, the internal electrodes exposed on the side surface serve as a medium for promoting sintering inside the dielectric,
Sintering can be performed well in a short time.

[Brief description of drawings]

FIG. 1 is a cross-sectional plan view of a multilayer capacitor according to an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) show ceramic green sheets used to manufacture a conventional multilayer capacitor and formed thereon. FIGS. 3 (a) and 3 (b) are plan views showing the shape of the internal electrode material, and FIGS. 3 (a) and 3 (b) illustrate the shape of the mother ceramic green sheet used for mass production of conventional multilayer capacitors and the shape of the mother internal electrode material formed thereon. FIG. 4 is a perspective view for explaining the shape of a ceramic green sheet as a dielectric sheet used for manufacturing one embodiment of the present invention and the shape of an internal electrode material formed thereon. 5 is a perspective view showing a laminated body, FIG. 6 is a perspective view for explaining a step of laminating a mother ceramic green sheet, and FIGS. 7 (a) and (b) are internal electrodes in a conventional example and an example. Lumber FIGS. 8A and 8B are cross-sectional views for explaining the shape of the side edge, and FIGS. 8A and 8B are schematic diagrams for explaining the shape of the laminated body after pressure bonding in the conventional example and the example, respectively. FIG. 8 is a sectional view, and FIG.
VIII-VIII is a sectional view of a portion taken along the line, FIG. 9 is a perspective view showing a state where a resist material is applied to the side surface of the sintered body, and FIG. 10 is a plan sectional view for explaining the internal electrode shape after etching. FIG. 11 is a schematic enlarged cross-sectional view showing voids formed by etching, and FIG. 12 is a perspective view of a multilayer capacitor according to an embodiment of the present invention. In the figure, 11 and 12 are ceramic green sheets as dielectric sheets, 11a, 11b, 12a and 12b are edges, and 11c, 11d and 12
c, 12d are side edges, 13, 13a to 13c, 14, 14a to 14c are internal electrode materials, 17, 19 are mother ceramic green sheets, 18a, 18b, 20
a and 20b are mother internal electrode materials, 25 is a sintered body, and 25a and 25b are first and second
Side surfaces, 25c and 25d are the third and fourth side surfaces, 26a and 26b are resist materials, 34 and 35 are side margin regions, 34a and 35a are voids, and 36 and 3 are
7 indicates an external electrode.

Claims (1)

[Claims] 1. A laminated-type dielectric body in which a plurality of dielectric layers are laminated with an internal electrode interposed therebetween, and the width of the internal electrode is the same as the width of the dielectric layer. On the side surface of the laminated dielectric in which the side edge of the internal electrode is exposed,
In a method of manufacturing a multilayer capacitor, which comprises a step of forming a side margin region on a side of the internal electrode by etching the exposed side edge portion of the internal electrode, in a space in which the side margin region is formed. A method of manufacturing a multilayer capacitor, characterized in that the remaining etching liquid is heated or neutralized so as not to act as an etching agent.