JPH0382006A - Laminated capacitor - Google Patents

Abstract

PURPOSE:To obtain a laminated capacitor, size of which can be made smaller 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 removing the side edge section of an internal electrode through etching, etc., and filling an air gap shaped by the formation of the side margin region with a sealing medium. CONSTITUTION:In a laminated capacitor, which has a laminated type dielectric, in which a plurality of dielectric layers are piled while interposing internal electrodes 13, 14 on the inside and in which the width of the internal electrodes 13, 14 is made narrower than said electric layers and side margin regions 34, 35 are shaped onto the sides of the internal electrodes 13, 14 by the narrowing of the width of the internal electrodes, the side margin regions 34, 35 are formed by etching or physically removing the side edge sections exposed of the internal electrodes 13, 14 on the side face of the laminated type dielectric, from which the side edges of the internal electrodes 13, 14 having the same width as that of said dielectric layer are exposed, and air gaps generated by shaping said side margin regions 34, 35 are filled with a sealing medium. A synthetic resin such as an epoxy resin is pressed and injected as said sealing medium.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an 81-layer capacitor, and more specifically,
The present invention relates to a multilayer capacitor with an improved side margin region between an internal electrode and a dielectric collar surface.

[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 is made by preparing ceramic green sheets 3 and 4 coated with 611 electrode material 1.2 made of conductive paste, and alternately applying a plurality of each to the ceramic green sheets 3 and 4. The laminate is laminated, the resulting laminate is pressed in the thickness direction, and then fired, and a loop electrode is formed on the side surface of the sintered body from which the internal electrode material 1.2 is drawn out.

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 3b of each ceramic green sheet 3.4.
, 4b (formed to extend toward jl).

In addition, each internal electrode material l.

2 is the @edge 3c of the ceramic green sheets 3 and 4;
The width is such that a side margin region 5 of width X is left between 3d, 4c, and 4d.

The side margin region 5 is provided by the internal electrode material 1
．． This is to improve the adhesion between the ceramic electric green sheets located above and below 2, and to prevent the internal electrode materials 1.2 from coming into contact with each other on the side surfaces of the sintered body after sintering. Therefore, conventionally, in multilayer capacitors, internal electrode material 1
, 2, it was essential to form a side margin area 5 with a wide width.

(Technical problem to be solved by the invention) However,
Naturally, when the width X of the side margin region 5 is wide, the internal electrode material l.

The width of 2 is pinched, which hinders the 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 matrix ceramic green sheet 6.7 is prepared, and a plurality of matrix internal electrode materials 8.9 formed on one main surface are alternately laminated. - Dot-dashed line A.

Individual laminates are obtained by cutting the laminate along the line B, and individual laminate capacitors are manufactured by drilling the individual laminates at the bottom of a pit.

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 misalignment inevitably occurs. There is a risk that the internal electrode material may be exposed on the side surface of the laminate. 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 the stacking misalignment occurs, the overlapping area of the internal electrode materials will also become small, 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 narrower, 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. Our goal is to provide the following.

[Means for Solving Technical Problems] The present invention has a laminated dielectric in which a plurality of dielectric layers are laminated with internal electrodes interposed therebetween, and the internal electrodes are more dense than the dielectric layers. In a multilayer capacitor in which the width of the internal electrode is narrowed, thereby providing a side margin region on the side of the internal electrode, the side margin region exposes the side edge of the internal electrode, which has the same width as the dielectric layer. It is formed by etching or physically removing the side edges of the internal electrodes that are exposed on the sides of the dielectric, and the gaps created by forming the side margin regions are filled with a sealing material. It is characterized by being

Note that as the above-mentioned physical removal method, there are a reverse sputtering method in which the internal electrode material is scattered by sputtering, and a method in which the internal electrode material is moved to the outside by electrophoresis.

[Effect]

In the present invention, the side margin regions are formed by etching or physical removal after obtaining the laminated dielectric. Therefore, the width of the side margin region can be formed accurately, the overlapping area of the internal electrodes can be accurately controlled, and variations in capacitance can be reduced.

In addition, internal bridges with the same width as the dielectric layer are laminated, and the side margin area is formed by etching or physical removal after lamination. There is no need to expand
Therefore, a smaller, larger capacity multilayer capacitor can be obtained.

Moreover, since it uses a laminate in which internal electrodes with the same width as the dielectric layer are laminated, there is a high tolerance for lamination misalignment, making it easy to perform the lamination work and to minimize A multilayer capacitor having a wide side margin region can be obtained.

Furthermore, since the void created by forming the side margin region is filled with a sealing material, moisture resistance and the like will not deteriorate.

[Explanation of Examples]

A manufacturing method according to an embodiment of the present invention will be described with reference to FIGS. 4 to 10. 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 production of this example and an internal electrode material formed thereon. Internal electrode materials 13 and 14 are formed in the form of a film on the upper surfaces of the rectangular ceramic green sheets 11 and 12, respectively.

The ceramic green sheets 11 and 12 are obtained by shaping a ceramic slurry mainly composed 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. As the material Flε constituting the internal electrode material, various metal materials such as Ag or Ag-Pd can be used in addition to Nu and Cu. However, 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 end edge 11a of 1 toward the opposite end edge llb, but not to reach the end edge 11b. Further, the width of the internal electrode material 13 is the same as the width of the ceramic green sheet 11. That is, the tI11 edge 11 of the ceramic green sheet 11
The internal electrode material 13 is formed in a width that extends to the entire width between c and lid.

The internal electrode material 14 is also configured in the same manner as the internal electrode material 13. However, ceramic green sea) 11.
When stacking 12, internal electrode material 13 and internal electrode material 14
Ceramic green sheet 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,
The ceramic green sheets 16 are stacked alternately, and the ceramic green sheets 16 to which no internal electrode material is attached are placed on top.
It is.

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
-14c is drawn out to the second side surface 15b. Also,
The internal electrode materials 13a-13c, 14a-14e are also exposed on the third and fourth side surfaces 15c, 15d of the laminate 15.

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 internal electrode material 1 to break down as shown in FIG. 6(a). A raised portion 21a is provided on the side 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 causes of layer peeling after sintering.

On the other hand, in this embodiment, as shown in a corresponding cross-sectional view in FIG.

Since it is formed to span the entire width between the inner electrode members 11a, the thickness of the inner electrode member 3 is uniform in the radial direction. Therefore,
It is possible to effectively prevent the occurrence of mites due to non-uniform thickness of the internal electrode material.

Returning to FIG. 5, prior to firing, the laminate 15 is pressed in the thickness direction to bring the ceramic green sheets into close contact with each other. In this case, in the laminate 15 of this embodiment,
The internal electrode materials 13a to 13C114a to 14c are the third.
Since it is formed to span the entire width between the fourth side surfaces 15c and 15a, as shown in the schematic cross-sectional view in FIG. 7(b) along the line ■-■ in FIG. Pressure bonding can be performed so that the thickness is uniform in the Y direction.

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, the The thickness becomes thinner in the portion Z where the margin region is formed, and the thickness of the laminate at the portion where the internal electrode material 1.2 is formed and the thickness of the side portion 2 where the side margin region is formed. Due to this difference, delamination tends to occur on the side surfaces of the resulting sintered body.

Therefore, in the laminate of this example, the occurrence of delamination due to such reasons can be effectively prevented.

Next, the laminated body 15 shown in FIG. 5 which has been pressed in the lamination direction is fired to obtain a sintered body as a laminated dielectric. Furthermore, as shown in FIG. 8, the first . The second side surface is a resist material 26a.

26b. These resist materials 26a and 26b are
It is made of a material that is not attacked by the etchant used in the etching described below, and for example, synthetic resin such as epoxy resin can be used.

The internal electrode material 13 is baked into the sintered body 25 when the ceramic is fired.
a to 13c and 14a to 14c are formed. In addition,
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 13c, 14a to 14c 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 material constituting the internal electrodes 13a-13c, 14a-14c. 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 N+ is used, an appropriate etchant capable of etching such metal material is used.

The state after etching is shown in a plan sectional view in Fig. 9.
As is clear from the figure, in the sintered body 25, the two sides 32 and 33 adjacent to the edge 31 where the internal electrode 13a is drawn out to the first side surface 25a of the sintered body 25 are Margin area 34°35 as 3rd. fourth side 25c,
25d, the third. Fourth aspect 25
c, has been retreated inward from 25d. This means that both side edge portions of the internal electrode 13a are etched by etching, thereby forming side margin regions 34 and 35.

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

Furthermore, as is clear from FIG. 10, in the portion where the side margin region is formed, a void 3 is formed by etching.
4a and 35a are formed.

After etching, the sintered body 25 is washed with water or the like to remove the etchant. However, it is difficult to completely remove the residual etchant, especially the etchant remaining in the voids 34a and 35a, by washing with water alone.Therefore, in this embodiment, the sintered body 25 is then placed in a heated atmosphere. , to remove residual etchant by scattering it.

Note that the above-mentioned heating may utilize heat given in the step of baking the external electrodes, which will be described later. In that case, the removal of the residual etchant and the baking of the external electrodes can be performed in the same step.

Further, the purpose of removing the residual etchant is to prevent corrosion of the internal electrodes due to the residual etchant. Therefore, a method other than heating may be used as long as it is possible to remove the etching effect.For example, if the etchant is a strong acid, the remaining etchant may be neutralized by immersion in an alkaline solution.

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

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 the ceramic green sheets and internal electrode materials are laminated 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 region. In other words, the side margin area 34.3 is narrower than the conventional example.
5 can be formed. Therefore, it can be seen that a small-sized, large-capacity multilayer capacitor can be realized.

Note that when the laminate 15 is obtained, the internal electrode material may sag from the portion exposed on the side surface, but even if such sagging internal electrode material exists, it is reliably removed by the above etching.

Next, a conductive paste containing, 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 as shown in FIG.
．． form 37. The external electrode 36 is connected to the internal electrodes 13a~
13c, the external electrode 37 is electrically connected to the internal electrodes 14a to 14e.

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 is achieved, for example, by heating the multilayer capacitor shown in FIG. 11 for a predetermined time in an oxidizing atmosphere. At the 33rd fourth side surface 25c, 25d of the sintered body 25, the internal electrode 13
Because the side edges of ax13c, 14a to 14e 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, and the internal electrodes are easily oxidized. An oxide film is formed on the electrode side edge. The formation of this oxide film effectively increases the adhesion strength between the internal electrodes and the ceramics. This is because, when oxidized, a chemical bond is formed between the dielectric ceramic and the internal electrode.

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

Note that the above oxidation treatment may be performed at any stage after the side margin regions 34 and 35 are formed by etching. That is, oxidation treatment may be performed prior to forming the external electrodes 36 and 37.

Finally, as shown in FIG. 1, a synthetic resin 39 such as an epoxy resin is injected under pressure into the gaps 34a and 35a in FIG. 10 to seal the side surfaces 25e and 25d of the sintered body 25. Note that as the sealing material, in addition to synthetic resin, any material such as rubber can be used.

The filling of the sealing material described above may be performed after the formation of the external electrodes (or may be performed prior to the formation of the external electrodes).
The multilayer capacitor of this example filled with the sealing material was
Figure 2 shows a perspective view. Since the voids are filled with the sealing material, there is no risk of deterioration in moisture resistance in this example, and therefore a multilayer capacitor with excellent reliability can be obtained.

In addition, in the above-mentioned embodiment, after etching,
Although a pair of external electrodes 36 and 37 are formed, the formation of the external electrodes may be performed prior to etching.

In the above embodiment, the internal electrodes 13a to 13c, 14a''1
Since the electrode 4c is made of inexpensive Ni or Cu, it is possible to reduce the electrode cost. Further, since the mother ceramic green sheets can be laminated without worrying too much about lamination misalignment, the manufacturing process is simplified and the mass production cost of multilayer capacitors can be effectively reduced.

Preferably, the side surface of the sintered body on which the external electrodes 36 and 37 are formed is 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 reliability of electrical connection with external electrodes 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 (in that case, if a material that is not etched by an etchant is used, it can also have the function of the resist materials 26a and 26b described above. In other words, the external electrodes The resist material 26a, 26b may be used as the base electrode for formation.In this case, it is not necessary to remove the resist material.

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

Furthermore, the present invention can also be applied to a wound type capacitor formed by winding a long ceramic green sheet or resin film together with an internal electrode formed on its main surface. It should be pointed out that type capacitors are also included in the multilayer capacitors referred to in the present invention.

(Effects of the Invention) As described above, in the present invention, the side margin regions on the sides of the internal electrodes are formed by etching or physically removing the side edges of the internal electrodes. That is, since the side margin region is formed by etching or physical removal after lamination, it is possible to accurately form the side margin region with the minimum necessary width without considering lamination misalignment or the like. Therefore, it is small in size and has a large capacity.
Moreover, a multilayer capacitor with less variation in capacitance value can be obtained.

In addition, since the side margin area is formed by etching or physical removal 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 improve positioning tolerance when laminating dielectric sheets. Since the range is widened, lamination work can be performed 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, thereby reducing the cost of the multilayer capacitor.

Furthermore, since the voids created by the formation of the side margin regions are filled with the sealing material, there is little risk of deterioration in moisture resistance, making it possible to obtain a highly reliable multilayer capacitor.

[Brief explanation of drawings]

Figure 1 is a cross-sectional 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 sheet formed thereon. Each plan view showing the shape of the internal electrode material, 3rd
Figures (a) and (b) are plan views for explaining the shapes of the green sheet and the thick internal electrode material formed thereon, which are used in the mass production of conventional multilayer capacitors. 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 an internal electrode material formed thereon; FIG. 5 is a perspective view showing a laminate; Figure 6(a) and (
b) is each cross-sectional view for explaining the shape of the side edge of the internal electrode material in the conventional side and the example, and FIG. 7(a)
and (b) are schematic cross-sectional views for explaining the shapes of the laminates after crimping in the conventional example and the example, respectively, and FIG. 7(b) is along the line ■-■ in FIG. 8 is a perspective view showing a state in which a resist material is applied to the side surface of the sintered body, 9rM is a plan sectional view for explaining the shape of the internal electrode after etching, and 1O is a cross-sectional view of the portion after etching. FIG. 11 is a schematic enlarged sectional view showing the created void, FIG. 11 is a perspective view of the multilayer capacitor before filling the sealing material, and FIG. 12 is a perspective view of the void filled with the sealing material. In the figure, 11.12 are ceramic green sheets as dielectric layers, lla, llb, ! 2a, 12b are edges, llc, lid, 12c, 12d are side edges, 13.
13a to 13e, 14.14a to 14e are internal electrode materials,
17.19 is the mother ceramic green sheet, 18a, 1
8b, 20a. 20b is a thick internal electrode material, 25 is a sintered body, and 25a. 25b is the first. 2nd side surface, 25e and 25d are third and fourth side surfaces, 26a and 26b are resist materials, 34.35 is a side margin area, 34a and 35a are voids, 36.3
7 is an external electrode, and 39 is a synthetic resin as a sealing material.

Claims (1)

[Claims] It has a laminated dielectric in which a plurality of dielectric layers are laminated with internal electrodes interposed therebetween, and the width of the internal electrodes is narrower than that of the dielectric layers. In a multilayer capacitor in which a side margin region is provided on the side of an internal electrode, the side margin region is formed of a multilayer dielectric in which the internal electrode has the same width as the dielectric layer and side edges thereof are exposed. It is formed by etching or physically removing the exposed side edge portion of the internal electrode on the side surface, and the gap created by forming the side margin region is filled with a sealing material. multilayer capacitor.