JPH0831396B2 - 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 reduce the size and 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 1, 2 and to prevent the internal electrode materials 1, 2 from being exposed on the side surface 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
In order to increase the capacity, it is preferable that the width x of the side margin region 5 is narrow.

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 and 7 in which the plurality of mother internal electrode materials 8 and 9 are formed, some lamination deviation is unavoidable, and as a result, in the individual laminated bodies after cutting. The internal electrode material may be exposed on the side surface of the laminate. If the internal electrode member is exposed on the side surface of the laminated body, a withstand voltage defect or a short circuit between the internal electrode members 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),
When the side margin region 5 of (b) is small, the adhesion strength between the upper and lower ceramics is not sufficient, which may cause layer 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 method for manufacturing a multilayer capacitor according to the present invention includes a rectangular dielectric sheet having one main surface, from one edge of the dielectric sheet to the other edge side facing the one edge, but the other edge. And the one edge from which the internal electrode material is drawn out is alternately opposite to the step of forming the internal electrode material over the entire width between the side edges connecting both end edges so as not to reach A plurality of the above-mentioned dielectric sheets to obtain a laminated type dielectric, and a step of forming a laminated type dielectric from the edge of the dielectric sheet where the internal electrode material is drawn out. The step of covering the first and second side surfaces with a resist material made of the material forming the underlayer of the external electrode, and exposing the third and fourth side surfaces of the dielectric derived from the both end edges of the dielectric sheet. The internal electrodes that are And a step of forming a side margin region between the third and fourth side surfaces and the internal electrode, and a pair of the side surface of the resist material functioning as the underlayer on the first and second side surfaces of the dielectric. And a step of forming an external electrode.

Further, in the method for manufacturing a multilayer capacitor of the present invention, a plurality of mother internal electrode materials are formed on one main surface of a rectangular mother dielectric sheet so as to extend between opposing edges of the mother dielectric sheet. Alternatively, the above-mentioned laminated individual dielectric may be obtained by laminating the mother dielectric sheets having the mother internal electrode material formed thereon and cutting the laminated mother dielectrics in the stacking direction.

[Action]

In the manufacturing method of the present invention, the side margin region is formed by etching after stacking the dielectric sheets. 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.

In addition, the internal electrode material is formed over the entire width between the side edges of the dielectric sheet, and the side margin regions are formed by etching after the dielectric sheets are stacked. There is no need to increase the width of the side margin area. Therefore, a smaller and larger-capacity multilayer capacitor can be obtained.

Furthermore, since the internal electrode material is formed over the entire width of the dielectric sheet, even if the internal electrode material sags due to cutting or the like from the portion exposed on the side surface of the internal electrode material at the stage of the laminated body. However, such a sag is surely removed by etching.

Moreover, since the dielectric sheets on which the internal electrode materials are formed are laminated over the entire width between the side edges of the dielectric sheets, the tolerance for the lamination deviation is large, so that the lamination work can be easily performed. Therefore, it is possible to easily and stably obtain the multilayer capacitor having the side margin region having the minimum necessary width.

Further, since the resist material is applied to the first and second side surfaces prior to the etching, there is no risk of etching the internal electrode portion connected to the external electrode during the etching. Furthermore, since the resist material also functions as a base layer of the external electrode, it is not necessary to perform the step of removing the resist material.

[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 sheet used in the manufacture of this example and an internal electrode material formed thereon. On the upper surface of the rectangular ceramic green sheets 11 and 12, respectively,
The internal electrode materials 13 and 14 are formed in a film shape.

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 conductive 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 laminated body 15, three first and second ceramic green sheets 11 and 12 are alternately laminated, and a ceramic to which an internal electrode material is not provided on the uppermost portion (and also on the lowermost portion if necessary). Gree sheet 16
Are appropriately stacked.

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.

When the laminated body 15 is obtained, 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 so as to extend from one edge 19a of the ceramic green sheet 19 to the other 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 end view of FIG. 8 (b) taken along the line -VIII, crimping can be performed so that the thickness is 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 thin 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 electrodes 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 sintered body as a laminated dielectric. Furthermore, the ninth
As shown in the drawing, the first and second side surfaces of the obtained sintered body 25 are covered with resist materials 26a and 26b. This resist material 26a, 26b
Is made of a material that is not attacked by an etchant used in etching described later, and is also made of a material that forms a base layer of an external electrode described later, that is, a conductive material.

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 an 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 an internal electrode material, an appropriate etchant capable of etching such a metal material is used. Can be

FIG. 10 is a plan sectional view showing the inside of the sintered body 25 with the resist materials 26a and 26b omitted. As is apparent from FIG. 10, in the sintered body 25, two sides 32, 33 adjacent to the end edge 31 of the internal electrode 13a extended to the first side surface 25a of the sintered body 25 are formed. , The side margin regions 34 and 35 are formed between the third and fourth side faces 25c and 25d, respectively.
It is retracted inward from c and 25d. This means that both side edge portions of the internal electrode 13a are etched by etching, whereby the side margin regions 34 and 35 are formed.

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

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.

Finally, a conductive paste mainly composed of Ag, for example, is applied onto the resist materials 26a and 26b and baked to form a pair of external electrodes 36 and 37 as shown in FIGS. 1 and 11. The external electrode 36 includes the internal electrodes 13a to 13c and the external electrode 37.
Are 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 subjecting the multilayer capacitor of FIG. 11 to heat treatment in an oxidizing 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, by performing the above-described oxidation treatment, it becomes possible to further improve the adhesion between the internal electrodes 13a to 13c, 14a to 14c and the dielectric ceramics.

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, in order to prevent the corrosion of the internal electrodes due to the residual etchant, the sintered body 25 may be placed in a heating atmosphere after the etching to remove the residual etchant. When the external electrodes 36 and 37 are formed by baking, the residual etchant can be removed by utilizing the heating during the baking.

When the etchant used is a strong acid such as HNO ₃ , the sintered body may be immersed in an alkaline solution for neutralization. This is also because this neutralization treatment can prevent corrosion of the internal electrodes due to the residual etchant.

Further, the side margin region is formed by performing the above etching, in which case the internal electrodes 13a to 13c, 1
Since 4a to 14c are to be etched, the voids 38 shown in the sectional view of FIG. 12 are formed in the etched portions. Therefore, preferably, a synthetic resin 39 such as an epoxy resin is injected under pressure into the void 38 to obtain a sintered body.
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 stacked without leaving a stacking deviation or the like as an extra device, the manufacturing process can be simplified and the mass production cost of the multilayer capacitor can be effectively reduced.

As described above, in this embodiment, the resist materials 26a and 26b made of the material forming the underlayer of the external electrode are previously formed on the first and second side surfaces 25a and 25b of the sintered body 25, External electrodes are formed on the resist materials 26a and 26b. That is,
Since the resist material also serves as the base electrode for forming the external electrode, it is not necessary to remove the resist material.

In the above-described embodiment, the side edges of the internal electrodes are etched using a chemical agent such as nitric acid as an etchant, but the actual etching is performed by immersing the sintered body in the etchant or in the rotating barrel. Is stored, the sintered body is put into the barrel, and the barrel is rotated.

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

〔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, the cost of the multilayer capacitor can be reduced.

Further, since the internal electrode lead-out edge is covered with the resist material prior to the etching, there is no possibility that the internal electrode lead-out edge is etched by the etching. In addition, since the resist material also serves as the base layer of the external electrode, it is not necessary to perform a complicated process of removing the resist material.

In addition, preferably, by forming a mother dielectric sheet on which a mother internal electrode material is formed and stacking the laminate to form individual laminated dielectrics, the above-described laminated capacitor can be efficiently mass-produced.

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

[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 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 perspective view of a multilayer capacitor according to an embodiment of the present invention, and FIG. 12 is a sectional view showing a state in which a sealing material is filled. 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 third and fourth side surfaces, 26a and 26b are resist materials, 34 and 35 are side margin regions, and 36 and 37 are external electrodes.

Claims (2)

[Claims] 1. A rectangular dielectric sheet is provided on one main surface thereof so as not to reach the other end edge from one end edge of the dielectric sheet toward the other end surface side facing the one end edge. And a step of forming an internal electrode material over the entire width between the side edges connecting the both end edges, so that the one edge from which the internal electrode material is drawn out is alternately on the opposite side, A step of laminating a plurality of dielectric sheets to obtain a laminated-type dielectric; and a step of forming first and second side surfaces of the laminated-type dielectric derived from an edge of the dielectric sheet from which an internal electrode material is drawn out. A step of coating with a resist material made of a material forming a base layer of the external electrode, and an internal electrode material exposed on the third and fourth side surfaces of the laminated dielectric derived from the side edge of the dielectric sheet. By etching the portion with an etching agent that does not attack the resist material, A step of forming a side margin region between the third and fourth side surfaces and the internal electrode; and a pair of external electrodes on the resist material on the first and second side surfaces of the laminated dielectric. A method of manufacturing a multilayer capacitor, comprising: 2. A plurality of mother internal electrode materials are formed in parallel on one main surface of a rectangular mother dielectric sheet so as to extend between opposing edges of the mother dielectric sheet at a predetermined distance. The step of: stacking a mother dielectric sheet having the mother internal electrode material formed thereon to obtain a laminated mother dielectric; and cutting the laminated mother dielectric in a stacking direction. And a step of obtaining the laminated dielectric body according to claim 1.