JPH0382007A - Manufacture of laminated capacitor - Google Patents

Abstract

PURPOSE:To obtain a laminated capacitor, size of which can be made small-than and capacitance of which can be made larger than conventional devices, a capacitance value of which is hardly reduced and which can be manufactured through a comparatively simple process by forming a side margin region by etching an internal electrode exposed to the side face of a dielectric. CONSTITUTION:Internal electrodes 13, 14 are shaped onto one main surface of a rectangular dielectric sheet so as not to reach the other end edge toward the other end edge side from one end edge of one main surface and extending over overall width between side edges, and a plurality of said dielectric sheets are laminated so that one end edges, from which the internal electrode materials 13, 14 are led out, are positioned alternately on the reverse side, thus acquiring a laminated type dielectric 25. The first and second side faces 25a, 25b of the dielectric 25 from which the internal electrode materials 13, 14 are led out are laminated by resist materials 26a, 26b, and internal electrode material sections exposed to the third and fourth side faces 25c, 25d of the dielectric 25 are etched, thus forming side margin regions 34, 35. The resist materials 26a, 26b are removed, and a pair of external electrodes are shaped onto the first and second side faces 25a, 25b of the dielectric 25.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a multilayer capacitor, and more specifically, the present invention relates to a method for manufacturing a multilayer capacitor, and more specifically, to an improved method for forming a side margin region between an internal electrode and a dielectric side surface. The present invention relates to a method of manufacturing a multilayer capacitor.

[Conventional technology]

Multilayer capacitors are widely used to make capacitors smaller and larger in capacity. For example, as shown in FIGS. 2(a) and 2(b), a multilayer capacitor includes an internal electrode material 1 made of conductive paste. A plurality of ceramic green sheets 3.4 coated with internal electrode materials 1. This is obtained by forming an external electrode on the side surface of the drawn sintered body of No. 2.

By the way, the internal electrode material 1.2 formed on the ceramic green sheets 3.4 extends from the first edge 3a, 4a to the second edge a3 of each ceramic green sheet 3.4.
b, is formed to extend toward the 4b side. In addition, each internal electrode material l.

2 is the side edge 3c of the ceramic green sheet 3.4;
3d, 4c, and 4d, the width is such that a wide side margin area 5 is left.

The side margin region 5 is provided by the internal electrode material 1
．． This is to improve the adhesion between the ceramic green sheets located above and below 2 and to prevent the internal electrode material 1.2 from being exposed on the side surface of the sintered body after sintering. Therefore, conventionally, in multilayer capacitors, internal electrode material 1
．． It was essential to form a side margin region 5 having a width of X on the sides of 2.

[Technical problem to be solved by the invention] However,
When the width X of the side margin region 5 is wide, the width of the internal electrode material 1.degree.2 is naturally pinched, which impedes an increase in capacity.

Therefore, in order to achieve smaller size and larger capacity, it is preferable that the width X of the side margin region 5 is narrower.

On the other hand, when mass-producing multilayer capacitors, Fig. 3(a)
, As shown in (b), a relatively large mother cell electrode green sheet 6.7 was prepared, and a plurality of bone internal electrode materials 8.9 formed on one main surface were alternately laminated. Later, - dotted chain line A.

Individual laminates are obtained by cutting the laminate along line B, and individual laminate capacitors are produced by drilling the individual laminates.

However, when laminating the matrix green sheets 6.7 on which a plurality of bone internal electrode materials 8.9 are formed, some lamination misalignment inevitably occurs, and as a result, after cutting, the individual laminated There is a possibility that the internal electrode material may be exposed on the side surface of the laminate inside the body. If the internal electrode materials are exposed on the side surfaces of the laminate, voltage resistance failure or short circuits between the internal electrode materials occur.

In addition, if the internal electrode material reaches near the side surface of the sintered body, even if it is not exposed, that is, Fig. 2 (a), (b)
), the adhesion strength between the upper and lower ceramic layers is not sufficient, causing layer peeling after sintering.

Furthermore, if a lamination misalignment occurs, the overlapping area of the internal electrode materials will also become smaller, and there is a risk that the capacitance value will be lower than the designed capacitance.

For the above-mentioned reasons, although it is preferable that the width X of the side margin region 5 be narrow, it is necessary to make the width X larger than necessary, which hinders miniaturization and increase in capacity. In addition, variations in capacitance and delamination due to stacking misalignment tended to occur.

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

[Means for solving technical problems]

The method for manufacturing a multilayer capacitor according to the present invention is to apply the following steps to one main surface of a rectangular dielectric sheet from one edge of the ljF dielectric sheet.
An internal electrode material is formed extending toward the other edge facing the one edge, but not reaching the other edge, and spanning the entire width between the side edges connecting the two edges. a step of laminating a plurality of the dielectric sheets so that the one edge from which the internal electrode material is pulled out is alternately on the opposite side to obtain a laminated dielectric, and the dielectric sheet The first part of the dielectric of the laminated mold originates from the edge from which the internal electrode material of A step of covering the second side surface with a resist material, and a step of covering the second side surface with a resist material,
．． The internal electrodes exposed on the fourth side surface are etched using a processing material 52 that does not attack the resist material. forming a side margin region between the fourth side surface and the internal electrode; removing the resist material; A step k of forming a pair of external electrodes on the second side surface is provided. Note that this step may be performed prior to the step of forming the external electrodes and the step of covering with the resist material.

Furthermore, in the method for manufacturing a multilayer capacitor of the present invention,
A plurality of base internal electrode materials are formed on one principal surface of a rectangular base dielectric sheet so as to extend between opposing edges of the base dielectric sheet, and the base dielectric sheet has the base internal electrode materials formed thereon. The laminated individual dielectrics described above may be obtained by laminating the laminated base dielectrics and cutting the laminated base dielectrics in the lamination direction.

[Effect]

In the manufacturing method of the present invention, the side margin regions are formed by etching after laminating the dielectric sheets. Therefore, the width of the side margin area can be precisely formed, and the width of the inside! The overlapping area of the poles can be accurately controlled, and capacitance variations can be reduced.

In addition, since the internal electrode material is formed over the entire width between the side edges of the dielectric sheets, and the side margin area is formed by etching after laminating the dielectric sheets, the amount of material used is more than necessary in consideration of the misalignment of 11 layers. Therefore, it is not necessary to widen the radius of the side margin region, and therefore a smaller and larger capacity IN 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 sag from the exposed side of the internal electrode material during the laminate stage due to cutting, etc. , such scratches can be reliably removed by etching.

Moreover, since the dielectric sheet is made of a dielectric sheet in which internal electrode material is formed over the entire width between the side edges of the dielectric sheet, there is a high tolerance for lamination misalignment, so the lamination work can be easily performed. Therefore, a multilayer capacitor having a necessary minimum side margin area can be easily and stably obtained.

Furthermore, prior to etching, a resist material is first applied. Since it is applied to the second side surface, there is no risk that the internal electrode portion connected to the external electrode or the external electrode will be etched during etching.

[Explanation of Example] A manufacturing method of an example of the present invention will be described with reference to FIGS. 4 to 10. This example is applied to a method of manufacturing a multilayer capacitor using dielectric ceramics. It is something.

FIG. 4 is a perspective view for explaining a ceramic green sheet as a dielectric sheet used in the production of this example and an internal electrode material formed thereon. Internal electrode materials 13 and 14 are formed in the form of films on the upper surfaces of the rectangular ceramic green sheets 11 and 12, respectively.

The ceramic green sheets 11 and 12 are obtained by forming a ceramic slurry mainly made of dielectric ceramic into the shape shown in the figure.

The internal electrode materials 13 and 14 are constructed by applying a conductive paste mainly composed of a conductive material such as Ni or Cu. The materials that make up the internal electrode material are:
In addition to Ni and Cu, various metal materials such as Ag or Ag-Pd can be used. Moreover, it is necessary to use a material that can be etched with an appropriate etchant during etching, which will be described later.

The internal electrode material 13 is a rectangular ceramic green sheet 1
It is formed so as to extend from one edge 11a of 1 toward the opposite edge 11b, but not to reach the edge 11b. Further, the width of the internal electrode material 13 is the same as the radius of the ceramic green sheet 11. That is, the side edges 11c, 1 of the ceramic green sheet 11
The internal electrode material 13 is formed with a width that extends to the entire width between one layer.

The internal electrode material 14 is also configured in the same manner as the internal electrode material 13. However, 11.
When stacking 12, internal electrode material 13 and internal electrode material 14
Ceramic green sea) 1 in which internal electrode material 14 is drawn out so that
One edge 12a of the ceramic green sheet 11
It is located on the opposite side to one end edge 11a of.

By alternately stacking a plurality of ceramic green sheets 11 and 12 shown in FIG. 4, a laminate 15 shown in FIG. 5 can be obtained. In the laminate 15, the first. 2nd Ceramic Green Sea) 11.3 pieces each,
They are alternately laminated, and an appropriate number of ceramic green sheets 16 to which no internal electrode material is applied are further laminated on the top (or on the bottom if necessary).

Here, one of the three internal electrodes 13a to 13C is placed on the first side surface 15a of the laminate 15, and the other internal electrode material 14a is
x14c is drawn out to the second side surface 15b. Also,
Each internal electrode material 13a-13c, 14ax14c is also exposed to the 3rd degree fourth side surface 15c, 15d of the laminated body 15.

In order to obtain the laminate 15, in the actual mass production process, it is preferable to use the mother ceramic green sheet shown in FIG. Internal electrode material 1 extending from one end edge 17a to the other end &117b across
8a and 18b are formed. Similarly, internal electrode materials 20a and 20b are placed on one edge 19 of the ceramic green sheet 19 as the mother dielectric sheet. It is formed so as to extend from e to the other end edge 19b.

Then, by stacking a plurality of Ceramic Green Sea) 17.19 alternately in the direction shown in the figure and cutting them at the parts corresponding to the parts along the dashed-dotted lines A and B, the laminate 15 shown in Fig. 5 is obtained. Many similar structures can be obtained.

In this way, by using the mother ceramic ξtsk green sheets 17 and 19, the laminate 15 shown in FIG. 5 can be efficiently mass-produced. Moreover, the laminate 1 in FIG.
5, each internal electrode material 13a'-13c, 14a-14
c is the third. It is formed in such a width that it is also exposed to the fourth side surfaces 15c and 15d.

Therefore, the ceramic green sheet 17°19 in Fig. 6
Even if some misalignment occurs in the direction of arrow C in FIG. 6 when laminating the internal electrode materials, there will be no overlapping misalignment of the internal electrode materials in the direction of arrow C in the obtained laminated dielectric 15. Even if some unavoidable lamination misalignment occurs when laminating the ceramic green sheets 17.19, the laminated body 15 has little variation in electrode amount or area.
can be obtained stably.

In addition, in the conventional example shown in FIG. 2, when a conductive paste for configuring the internal electrode material 1 is applied, the surface tension of the paste causes the side of the internal electrode material 1 to A raised portion 21a on the edge.

21b was formed. 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 reasons why the layers tend to peel off after sintering.

On the other hand, in this embodiment, as shown in a corresponding cross-sectional view in FIG. 7(b), the internal electrode material 13 is formed on the side edge 11C of the ceramic green sheet 11.

Since the internal electrode material 13 is formed to span the entire width between the electrodes 11a, the thickness of the internal electrode material 13 is uniform in the width direction. Therefore,
It is possible to effectively prevent the occurrence of delamination caused by non-uniform thickness of the internal electrode material.

Returning to FIG. 5, the laminate 15 is pressed in the thickness direction prior to being placed at the bottom of the pit, so that the ceramic green seams 1 are brought into close contact with each other. In this case, in the laminate 15 of this embodiment,
Internal electrode material 13ax13c.

14a-14c are the third. Since it is formed to span the entire width between the fourth side surfaces 15c and 156,
As shown in the schematic cross-sectional view of FIG. 8(b) along the line, the pressure bonding can be performed so that the thickness is uniform in the Y direction of FIG. 5.

On the other hand, the 21st! In the conventional example using the ceramic green sheet shown in f, the side margin region 5 is formed in advance, so that the side margin region in the laminate 15 is formed as shown in FIG. The thickness of the laminate becomes thinner in the part where the internal electrode material 1.2 is formed and the thickness of the laminate in the side area where the side margin area is formed. Delaminosis tended to occur on the sides of the body. Therefore, the laminate of this embodiment can effectively prevent delamination from occurring due to such reasons.

Next, the laminate 15 shown in FIG. 5, which has been pressed in the stacking direction, is burned to obtain a sintered body as a laminate dielectric.

Furthermore, as shown in FIG. 9, the first . The second side is coated with resist +426a, 26b. The resist materials 26a and 26b are made of a material that is not attacked by etching (etching) used in etching, which will be described later, and for example, synthetic resin such as epoxy resin can be used.

Inside the sintered body 25, the internal electrode material 13 is formed by firing the above-mentioned internal electrode material during firing of the ceramics.
ax 13c, 14a to 14c are formed. Note that the reference numbers of the internal electrodes will be explained using the same reference numbers as those of the internal electrode materials described above.

Each of the internal electrodes 13a to 13e and IJa to 14e is connected to the third electrode of the sintered body 25 except for the portions covered with the resist materials 26a and 26b. It is exposed on the fourth side surfaces 25c and 25d.

Next, the third. Fourth side 25C, 25
d is etched using an etchant capable of etching the materials constituting the internal electrodes 13a to 13c and 14a to 14e. As an etchant, for example, a strong acid such as nitric acid can be used, but as an internal electrode material, Cu
When a metal material other than Nj is used, an appropriate etchant capable of etching such a metal material is used.

After etching, the resist materials 26a and 26b are removed. Removal of the resist materials 26a and 26b is performed by removing the sintered body 2.
5, 1st. This can be done by mechanically polishing the second side surface or by using a suitable chemical.

The state in which the resist materials 26a and 26b have been removed is shown in a cross-sectional plan view in FIG. 10. As is clear from FIG. The two sides 32.33 adjacent to the edge 31 drawn out to the side surface 25a form the side margin area 34.35.
3rd. The third side is formed between the fourth sides 25e and 25d. It is retreated inward from the fourth side surfaces 25e and 25d. This is done by etching the internal electrode 13.
This means that both side edge portions of a are etched, thereby forming side margin regions 34 and 35.

Side margin regions are similarly formed in the other internal electrodes f3b, 13e, 14a to 14c.

In this embodiment, the side margin regions 34 and 35 are formed by etching, so the third side margin regions 34 and 35 of the sintered body 25 are formed by etching. Fourth
A side margin region with an accurate width can be formed inward from the side surfaces 25e and 25d. Moreover, since the side margin regions 34 and 35 are formed after laminating the ceramic green sheets and the internal electrode material ε to obtain a laminate, an extra width of side margin is required to take into consideration lamination misalignment, etc. There is no need to form a side margin region 34.3, that is, the width of the side margin region 34.3 is narrower than in the conventional example.
5 can be formed. Therefore, it can be seen that a small-sized, large-capacity multilayer capacitor can be realized.

Finally, a conductive base material mainly composed of, for example, Ag is applied to the surface from which the resist materials 26a and 26b have been removed, and is baked, thereby forming a pair of external electrodes 36 and 37, as shown in FIGS. 1 and 11. form. The external electrode 36 is connected to the internal electrodes 13a to 13e, and the external electrode 37 is connected to the internal electrode 14a.
~14c electrically connected.

Preferably, after forming the external electrodes 36 and 37, the third. The fourth side surfaces 25c and 25d may be subjected to oxidation treatment. In this embodiment, the oxidation treatment may be performed by, for example, heating the multilayer capacitor shown in FIG. 11 for a predetermined time in an oxidizing atmosphere. , the third sintered body 25. At the fourth side surface 25c, 2.5d, the internal electrode 1 passes through a relatively narrow width side margin region 34.35.
Because the side edges of 3a to l3c and 14a to 14c are arranged, and the side margin region is formed by etching, the side edges of the internal electrodes are easily oxidized by the oxidizing atmosphere. , thereby forming an oxide film on the edge of the internal electrode. The formation of this oxide film effectively increases the adhesion strength between the internal electrodes and the ceramic. This is because a chemical bond is formed between the dielectric ceramic and the internal electrode when it is oxidized.

Therefore, by performing the oxidation treatment as described above, it is possible to further improve the adhesion between the internal electrodes 13a to 13c, 14a to 14c and the dielectric ceramic.

Note that the above oxidation treatment may be performed at any stage after the side margin regions 34.35 are formed by etching, that is, the oxidation treatment may be performed prior to the formation of the external electrodes 36.37. .

Furthermore, in order to prevent corrosion of the internal electrodes due to residual etchant, the sintered body 25 may be placed in a heated atmosphere after etching to remove residual etchant. In the case of formation, this baking can be performed using heating to remove residual etchant.

In addition, if the etchant used is a strong acid such as HNO, the sintered body may be immersed in an alkaline solution to neutralize it.This neutralization treatment also prevents corrosion of the internal electrodes due to residual etchant. Because you will get it.

Further, by performing the above etching, a side margin region is formed, in which case the internal electrode 13a-1
Since the portions 3c, 14a to 14c are etched, a gap 38 as shown in the cross-sectional view of FIG. 12 is formed in the etched portion. Therefore, preferably, a synthetic resin 39 such as an epoxy resin is injected into the void 38 under pressure to form the side surfaces 25c and 2 of the sintered body 25.
5d can be sealed. Note that as the sealing material, in addition to synthetic resin, any material such as rubber can be used.

The above-mentioned sealing treatment may also be performed after the formation of the external electrodes, or may be performed prior to the formation of the external electrodes.

Further, in the above embodiment, the pair of external electrodes 36 and 37 are formed after etching, but the external electrodes may be formed prior to etching.

In the above embodiment, the internal electrodes 13ax13c, 14ax1
Since 4c is constructed using inexpensive Ni or Cu, the electrode cost can be reduced. Further, since the base ceramic green sheets can be stacked without worrying too much about stacking misalignment, the manufacturing process is simplified and the mass production cost of multilayer capacitors can be effectively reduced.

Preferably, the side surfaces of the sintered body on which the external electrodes 36 and 37 are formed are coated with a conductive paste mainly composed of Ni, and then the external electrodes 36 and 37 are formed, so that the internal electrodes and the external The reliability of electrical connection with the electrode can be increased.

Further, in place of Ni, another conductive material layer is applied to the first layer of the sintered body 25. It may be applied to the second side surfaces 25a and 25b, and in that case, if a material that is not etched by the etchant is used, it can also have the function of the resist materials 26a and 26b described above. That is, the resist materials 26a and 26b can be used as base electrodes for forming external electrodes. In this case, removal of the resist material is not necessary.

In the embodiments described above, the side edges of the internal electrodes were etched using a chemical agent such as nitric acid as an etchant.
Actual etching can be performed by immersing the sintered body in an etchant, or by storing the etchant in a rotating barrel, placing the sintered body into the barrel, and rotating the barrel.

In the embodiments described above, a ceramic green sheet was used as the dielectric sheet, but the present invention is limited to a multilayer ceramic Q7 capacitor formed by laminating a plurality of ceramic green sheets and firing them together with the internal electrode material. In other words, a dielectric resin film can be used as the dielectric sheet, and the present invention can also be applied to a so-called multilayer film capacitor.

〔Effect of the invention〕

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 adjacent to the extended edge of the internal electrode. In other words, since the side margin region is formed by etching after lamination, it is possible to accurately form the side margin region with the minimum necessary radius without considering layer misalignment, etc.
It is possible to obtain a multilayer capacitor that has a large capacity and has less variation in capacitance value.

In addition, since side margin regions are formed by etching after lamination, it is possible not only to obtain a multilayer capacitor with a small size and large capacity as described above, but also to widen the positioning tolerance range when laminating dielectric sheets. La layer work can be done relatively easily. Furthermore, since the electrode pattern for forming internal electrodes is formed to have the same width as the dielectric layer, it is possible to reduce the number of types of electrode patterns. Therefore, it is possible to reduce the cost of the multilayer capacitor.

Furthermore, since the leading edge of the internal electrode or the external electrode connected to the external electrode is coated with a resist material prior to etching, there is no fear that the leading edge of the internal electrode or the external electrode will be etched.

Preferably, the above-described multilayer capacitors can be efficiently mass-produced by laminating and cutting a dielectric sheet with a mother internal electrode material formed thereon to form individual multilayer dielectrics.

Furthermore, when ceramic is used as the dielectric and is sintered before etching or other processing, the internal electrodes exposed on the side surfaces become a medium that promotes sintering inside the dielectric.
Sintering can be performed well in a short time.

[Brief explanation of drawings]

Figure 1 is a cross-sectional plan view of a multilayer capacitor according to an embodiment of the present invention, and Figures 2 (a) and (b) are ceramic green sheets used to manufacture conventional multilayer capacitors and the ceramic green sheets formed thereon. Each plan view showing the shape of the internal electrode material, FIGS. 3(a) and 3(b), explains the shape of the mother ceramic green sheet used in the 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 in manufacturing an embodiment of the present invention and the internal electrode material formed thereon. 5 is a perspective view showing a laminate, FIG. 6 is a perspective view for explaining the process of laminating mother ceramic green sheets, and FIGS. 7(a) and (b) are internal electrodes in the conventional example and the example. FIGS. 8(a) and 8(b) are cross-sectional views for explaining the shape of the side edges of the material, and FIGS. 8(b) is a sectional view of a portion along the line ■-■ in FIG. 5; FIG. 9 is a perspective view showing a state in which a resist material is applied to the side surface of the sintered body; FIG. 10 is a plan sectional view for explaining the shape of the internal electrode 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 filled with sealing material. It is. In the figure, reference numerals 11 and 12 indicate ceramic green sheets, lla and llb, as dielectric sheets. 12a, 12b are edges, lie, lid, 12c. 12d is the side edge, 13.13a to 13c, 14°14a
-14e are internal electrode materials, 17.19 are melon ceramic green sheets, f8a, 18b, 20a, 20b are mother internal electrode materials, 25 is a sintered body, 25a, 25b are first. The second side surface, 25e, 25d is the third side surface. Fourth side, 26a, 2
6b is a resist material, 34.35 is a side margin area,
36 and 37 indicate external electrodes. 2.

Claims (2)

[Claims] (1) On one main surface of a rectangular dielectric sheet, from one edge of the dielectric sheet toward the other edge opposite to the one edge so as not to reach the other edge. and forming the internal electrode material over the entire width between the side edges connecting the two end edges, and the step of forming the internal electrode material so that the one end edge from which the internal electrode material is pulled out is alternately on the opposite side. A step of laminating a plurality of dielectric sheets to obtain a laminated dielectric, and first and second side surfaces of the laminated dielectric originating from edges from which internal electrode materials of the dielectric sheet are drawn out. and etching the internal electrode material portions exposed on the third and fourth side surfaces of the laminated dielectric material originating from the side edges of the dielectric sheet without corroding the resist material. forming a side margin region between the third and fourth side surfaces and the internal electrodes by etching with a chemical agent; removing the resist material; 1. A method for manufacturing a multilayer capacitor, comprising: forming a pair of external electrodes on two side surfaces. (2) forming a plurality of base internal electrode materials in parallel at a predetermined distance on one main surface of a rectangular base dielectric sheet so as to extend between opposing edges of the base dielectric sheet; , the step of laminating the mother dielectric sheets on which the mother internal electrode material is formed to obtain a laminated mother dielectric, and cutting the laminated mother dielectric in the lamination direction, according to claim 1. characterized by comprising a step of obtaining a laminated dielectric material of
Method of manufacturing multilayer capacitors.