JP6975200B2 - Multilayer ceramic capacitors and their manufacturing methods - Google Patents

Description

The present invention relates to a monolithic ceramic capacitor to which a side margin portion is retrofitted and a method for manufacturing the same.

In recent years, as electronic devices have become smaller and have higher performance, there has been an increasing demand for larger capacities for multilayer ceramic capacitors used in electronic devices. In order to meet this demand, for example, it is effective to increase the crossing area of the internal electrodes of the monolithic ceramic capacitor as much as possible.

In order to increase the cross-sectional area of the internal electrodes, it is effective to add a side margin portion for ensuring the insulating property around the internal electrodes to the laminated chip in which the internal electrodes are exposed on the side surface. As a result, the side margin portion can be formed thinly, and the crossing area of the internal electrodes can be made relatively large.

On the other hand, in a laminated ceramic capacitor having a side margin portion attached to the side surface of the laminated chip, foreign matter derived from an internal electrode may adhere to the side surface of the laminated chip during the manufacturing process. As a result, the internal electrodes may conduct each other on the side surface of the laminated chip, and a short-circuit defect between the internal electrodes may occur.

In order to deal with this problem, for example, as in the invention described in Patent Document 1, a short-circuit defect between the internal electrodes on the side surface of the laminated chip is formed by forming an oxidation region having low conductivity at the end of the internal electrode. Can be prevented.

Japanese Unexamined Patent Publication No. 2009-016796

In a multilayer ceramic capacitor, the internal electrode may be deformed due to non-uniform shrinkage behavior during firing, not only when the side margin portion is retrofitted to the side surface of the laminated chip. Deformation of the internal electrode is likely to occur at the end of the internal electrode. Due to such deformation of the internal electrodes, the ends of adjacent internal electrodes may come into contact with each other.

In this case, as in the invention described in Patent Document 1, if an attempt is made to prevent a short-circuit defect between the internal electrodes by forming an oxidized region at the end of the internal electrode, a wide oxidized region is secured at the end of the internal electrode. There is a need to. As a result, the area of the region contributing to the capacitance formation in each internal electrode becomes small, so that the capacitance of the multilayer ceramic capacitor decreases.

In view of the above circumstances, an object of the present invention is to provide a monolithic ceramic capacitor capable of suppressing short circuit defects and securing a capacity, and a method for manufacturing the same.

In order to achieve the above object, the multilayer ceramic capacitor according to one embodiment of the present invention includes a laminated portion and a side margin portion.
The laminated portion includes a plurality of ceramic layers laminated in the first direction, a capacitance forming portion arranged between the plurality of ceramic layers and having a plurality of internal electrodes containing nickel as a main component, and the capacitance forming portion. It has a cover portion for covering the above first direction.
The side margin portion covers the laminated portion from a second direction orthogonal to the first direction.
The plurality of internal electrodes have an oxidation region adjacent to the side margin portion and in which metal elements forming an oxide together with nickel are unevenly distributed.
The capacity forming portion is adjacent to the first portion adjacent to the cover portion and the first portion in the first direction, and the dimension of the oxidation region in the second direction is the first portion. It consists of a second part, which is smaller than.

According to this configuration, the plurality of internal electrodes have an oxidation region adjacent to the side margin portion. As a result, conduction between the internal electrodes via foreign matter or the like on the side surface of the laminated portion is suppressed, so that short-circuit defects between the internal electrodes are suppressed.
Further, according to the above configuration, the oxidation region in the first portion where the internal electrode is easily deformed is wide, and the oxidation region in the second portion where the internal electrode is not easily deformed is narrow. As a result, in the first portion, the conduction between the internal electrodes due to the contact between the adjacent internal electrodes is effectively suppressed. Therefore, short-circuit defects of the monolithic ceramic capacitor are suppressed.
On the other hand, since the oxidation region in the second portion is narrowed, the capacity loss in the second portion is suppressed. As a result, the capacity of the monolithic ceramic capacitor can be secured.

The metal element may be at least one of magnesium and manganese.

In the method for manufacturing a multilayer ceramic capacitor according to an embodiment of the present invention, a plurality of ceramic layers laminated in the first direction and a plurality of internal electrodes arranged between the plurality of ceramic layers and containing nickel as a main component are provided. The capacitance forming portion to have and the covering portion covering the capacitance forming portion from the first direction and having a thickness of 15 μm or less in the first direction are oriented in a second direction orthogonal to the first direction. An unfired laminated chip having the above-mentioned side surface where the plurality of internal electrodes are exposed is produced.
A side margin portion containing a metal element that forms an oxide together with nickel, the concentration of the metal element being equal to or less than the concentration of the metal element in the cover portion, and the thickness in the second direction being 15 μm or less. Is coated from the second direction, so that an unfired element body is produced.
The unfired element is fired.

According to the above manufacturing method, the thickness of the cover portion in the first direction is 15 μm or less, and the thickness of the side margin portion in the second direction is 15 μm or less.
Further, the concentration of the metal element forming an oxide together with nickel in the cover portion is equal to or higher than the concentration of the metal element in the side margin portion.

As a result, when the unfired element is fired, the metal element that forms an oxide together with nickel and oxygen are added to the end of the internal electrode near the ridge of the capacitance forming portion rather than the end of the other internal electrodes. Many are supplied.
Therefore, more composite oxides containing metal elements are formed at the end of the internal electrode near the ridge of the capacitance forming portion than at the ends of the other internal electrodes, so that the oxidation region becomes wider. Therefore, in the vicinity of the ridge portion of the capacitance forming portion after firing, the conduction between the internal electrodes due to the contact between the ends of the adjacent internal electrodes is effectively suppressed. Therefore, short-circuit defects of the monolithic ceramic capacitor are suppressed.

On the other hand, when the unfired element is fired, more metal elements are supplied to the end of the internal electrode near the ridge of the capacity forming portion than to the ends of other internal electrodes, so that the capacity forming portion is formed. The amount of metal element supplied at the end of the internal electrode located near the center of the is relatively small.
As a result, the oxidation region formed at the end of the internal electrode located near the center of the capacitance forming portion is narrowed, so that the capacitance loss near the center of the capacitance forming portion is suppressed. Therefore, the monolithic ceramic capacitor can also secure the capacity.

By firing the unfired element body, an oxidation region adjacent to the side margin portion and in which the metal element is unevenly distributed may be formed on the plurality of internal electrodes.
In the capacity forming portion, in the first portion adjacent to the cover portion, the dimension of the oxidation region in the second direction is larger than that of the second portion adjacent to the first portion in the first direction. May be increased.

The metal element may be at least one of magnesium and manganese.

It is possible to provide a monolithic ceramic capacitor capable of suppressing short-circuit defects and securing a capacity, and a method for manufacturing the same.

It is a perspective view of the multilayer ceramic capacitor which concerns on one Embodiment of this invention. It is sectional drawing along the AA' line of FIG. 1 of the said monolithic ceramic capacitor. It is sectional drawing along the BB'line of FIG. 1 of the said monolithic ceramic capacitor. It is a schematic diagram which enlarges and shows the region P of FIG. 3 of the said monolithic ceramic capacitor. It is an enlarged sectional view of the element body of the conventional multilayer ceramic capacitor. It is a flowchart which shows the manufacturing method of the said monolithic ceramic capacitor. It is a top view which shows the manufacturing process of the said monolithic ceramic capacitor. It is a perspective view which shows the manufacturing process of the said monolithic ceramic capacitor. It is a top view which shows the manufacturing process of the said monolithic ceramic capacitor. It is sectional drawing which shows the manufacturing process of a multilayer ceramic capacitor. It is a perspective view which shows the manufacturing process of the said monolithic ceramic capacitor. It is a perspective view which shows the manufacturing process of the said monolithic ceramic capacitor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The drawings show X-axis, Y-axis, and Z-axis that are orthogonal to each other as appropriate. The X-axis, Y-axis, and Z-axis are common in all drawings.

[Overall configuration of multilayer ceramic capacitor 10]
FIGS. 1 to 3 are views showing a multilayer ceramic capacitor 10 according to an embodiment of the present invention. FIG. 1 is a perspective view of the monolithic ceramic capacitor 10. FIG. 2 is a cross-sectional view of the monolithic ceramic capacitor 10 along the AA'line of FIG. FIG. 3 is a cross-sectional view of the monolithic ceramic capacitor 10 along the line BB'of FIG.

The monolithic ceramic capacitor 10 includes a body 11, a first external electrode 14, and a second external electrode 15.
The element 11 typically has two sides oriented in the Y-axis direction and two main surfaces oriented in the Z-axis direction. The ridge connecting each surface of the element 11 is chamfered. The shape of the element body 11 is not limited to such a shape. For example, each surface of the element body 11 may be a curved surface, and the element body 11 may have a rounded shape as a whole.
The first and second external electrodes 14 and 15 cover both end faces in the X-axis direction of the element body 11 and extend to four surfaces connected to both end faces in the X-axis direction. As a result, in both the first and second external electrodes 14 and 15, the cross section parallel to the XY plane and the cross section parallel to the XY axis are U-shaped.

The element body 11 has a laminated portion 16 and a side margin portion 17.
The laminated portion 16 has a structure in which a plurality of flat plate-shaped ceramic layers extending along an XY plane are laminated in the Z-axis direction.

The laminated portion 16 has a capacity forming portion 18 and a cover portion 19.
The capacitance forming unit 18 has a plurality of first internal electrodes 12 and a plurality of second internal electrodes 13. The first and second internal electrodes 12 and 13 are alternately arranged along the Z-axis direction between the plurality of ceramic layers. The first internal electrode 12 is connected to the first external electrode 14 and is insulated from the second external electrode 15. The second internal electrode 13 is connected to the second external electrode 15 and is insulated from the first external electrode 14.

The first and second internal electrodes 12 and 13 are made of conductive materials, respectively, and function as internal electrodes of the multilayer ceramic capacitor 10. As the conductive material, a metal material containing nickel (Ni) as a main component is adopted.

As shown in FIGS. 2 and 3, the capacitance forming portion 18 includes a first portion 18a adjacent to the cover portion 19 and a second portion 18b adjacent to the first portion 18a in the Z-axis direction. Will be done. That is, the first portion 18a constitutes both ends of the capacitance forming portion 18 in the Z-axis direction, and the second portion 18b constitutes the central portion of the capacitance forming portion 18 in the Z-axis direction.

As shown in FIG. 3, the first portion 18a is covered with the cover portion 19 from the Z-axis direction and is covered with the side margin portion 17 from the Y-axis direction. As shown in the figure, the second portion 18b is covered with the first portion 18a from the Z-axis direction and is covered with the side margin portion 17 from the Y-axis direction.

The capacitance forming portion 18 is formed of ceramics. In the capacitance forming portion 18, a material having a high dielectric constant is used as a material constituting the ceramic layer in order to increase the capacitance of each ceramic layer between the first internal electrode 12 and the second internal electrode 13. As the material constituting the capacitance forming portion 18, for example, _{a polycrystal of barium titanate (BaTIO 3} ) -based material, that is, a polycrystal having a perovskite structure containing barium (Ba) and titanium (Ti) can be used. ..

The material constituting the capacitance forming portion 18 is not only barium titanate (BaTIO ₃ ) -based, but also strontium titanate (SrTiO ₃ ) -based, calcium titanate (CaTIO ₃ ) -based, and magnesium titanate (MgTIO ₃ ) -based. , Calcium zircate (CaZrO ₃ ) -based, calcium titanate (Ca (Zr, Ti) O ₃ ) -based, barium titanate (BaZrO ₃ ) -based or titanium oxide (TIO ₂ ) -based polycrystals. There may be.

The cover portion 19 has a flat plate shape extending along the XY plane and covers the upper and lower surfaces of the capacitance forming portion 18 in the Z-axis direction. The cover portion 19 is not provided with the first and second internal electrodes 12 and 13.

As shown in FIG. 3, the side margin portion 17 is formed on both side surfaces S1 and S2 of the capacitance forming portion 18 and the cover portion 19 facing in the Y-axis direction.

As described above, in the element body 11, the surfaces other than the X-axis direction end faces provided with the first and second external electrodes 14 and 15 of the capacitance forming portion 18 are covered with the side margin portion 17 and the cover portion 19. .. The side margin portion 17 and the cover portion 19 mainly have a function of protecting the periphery of the capacitance forming portion 18 and ensuring the insulating properties of the first and second internal electrodes 12 and 13.

The side margin portion 17 and the cover portion 19 are also formed of ceramics. The material forming the side margin portion 17 and the cover portion 19 is insulating ceramics, and the internal stress in the element 11 is suppressed by using a dielectric having the same composition system as the capacitance forming portion 18.

The side margin portion 17, the cover portion 19, and the capacitance forming portion 18 are, for example, magnesium (Mg), manganese (Mn), aluminum (Al), calcium (Ca), vanadium (V), chromium (Cr), zirconium (Zr). ), Molybdenum (Mo), Tungsten (W), Tantal (Ta), Niob (Nb), Silicon (Si), Boron (B), Ittrium (Y), Europium (Eu), Gadolinium (Gd), Dysprosium (Dy) ), Holmium (Ho), Elbium (Er), Itterbium (Yb), Lithium (Li), Potassium (K), Sodium (Na) and other metal elements may be further contained.

With the above configuration, in the monolithic ceramic capacitor 10, when a voltage is applied between the first external electrode 14 and the second external electrode 15, a plurality of layers between the first internal electrode 12 and the second internal electrode 13 are applied. A voltage is applied to the ceramic layer. As a result, in the multilayer ceramic capacitor 10, electric charges corresponding to the voltage between the first external electrode 14 and the second external electrode 15 are stored.

The laminated ceramic capacitor 10 according to the present embodiment may be provided with the laminated portion 16 and the side margin portion 17, and other configurations can be appropriately changed. For example, the number of the first and second internal electrodes 12 and 13 can be appropriately determined according to the size and performance required for the multilayer ceramic capacitor 10.
Further, in FIGS. 2 and 3, in order to make it easy to see the facing states of the first and second internal electrodes 12 and 13, the number of the first and second internal electrodes 12 and 13 is limited to four, respectively. However, in reality, more first and second internal electrodes 12 and 13 are provided in order to secure the capacity of the monolithic ceramic capacitor 10.

[Oxidation regions E1, E2]
FIG. 4 is an enlarged schematic view showing the region P shown in FIG. 3, and is an enlarged view showing the ends of the internal electrodes 12 and 13 in the first and second portions 18a and 18b.

As shown in FIG. 4, the first and second internal electrodes 12 and 13 have oxidation regions E1 and E2 formed on the end portions exposed on the side surfaces S1 and S2 of the laminated portion 16 which are regions whose conductivity is reduced by oxidation. Has been done. The oxidation regions E1 and E2 are adjacent to the side margin portion 17 as shown in FIG.

Here, the dimension D1 in the Y-axis direction of the oxidation region E1 formed at the ends of the internal electrodes 12 and 13 in the first portion 18a is the inside in the second portion 18b as shown in FIG. The oxidation region E2 formed at the ends of the electrodes 12 and 13 is longer than the dimension D2 in the Y-axis direction.

In FIG. 4, for convenience of explanation, the dimensions D1 of the plurality of oxidation regions E1 are shown equally, and the dimensions D2 of the plurality of oxidation regions E2 are shown equally. However, the dimension D1 may be different for each oxidation region E1, and the dimension D2 may be different for each oxidation region E2. In this case, the dimensions D1 and D2 can be the average value of all the oxidation regions E1 and E2.

The oxidation region E1 is preferably formed on all the ends of the internal electrodes 12 and 13 in the first portion 18a, but may not be formed on a part thereof. Similarly, the oxidation region E2 is preferably formed on all the ends of the internal electrodes 12 and 13 in the second portion 18b, but may not be partially formed.

In the element 11 according to the present embodiment, a characteristic composition distribution is observed in which the metal elements forming a composite oxide together with nickel (Ni) are unevenly distributed in the oxidation regions E1 and E2. Examples of such a metal element include magnesium (Mg) and manganese (Mn). The oxidation regions E1 and E2 are composed mainly of a composite oxide containing the metal element and nickel (Ni).

The composite oxide constituting the oxidation regions E1 and E2 is typically a ternary oxide containing magnesium (Mg) or manganese (Mn) and nickel (Ni). However, the composite oxide may contain both magnesium (Mg) and manganese (Mn), and may contain other metal elements listed above.

The dimensions D1 and D2 of the oxidation regions E1 and E2 can be, for example, in the range of several hundred to several thousand nm.

FIG. 5 is an enlarged partial cross-sectional view showing the element body 211 of the conventional multilayer ceramic capacitor 210. With reference to FIG. 5, the actions of the oxidation regions E1 and E2 according to the present embodiment will be described in comparison with the conventional multilayer ceramic capacitor 210. As shown in the figure, the element body 211 of the multilayer ceramic capacitor 210 has a capacitance forming portion 218, a cover portion 219 that covers the capacitance forming portion 218 from the Z-axis direction, and a capacitance forming portion 218 and a cover portion 219 on the Y axis. It has a side margin portion 217 that covers from the direction.

As shown in FIG. 5, the capacitance forming portion 218 has an internal electrode 212a near the cover portion 219 and an internal electrode 212b located near the center of the capacitance forming portion 218.

In the conventional monolithic ceramic capacitor 210, foreign matter derived from an internal electrode may adhere to the side surface of the unfired capacitance forming portion in the manufacturing process. As a result, the internal electrodes 212a and 212b may conduct each other via foreign matter on the side surface S3 of the capacitance forming portion 218 after firing, and a short-circuit defect may occur between the internal electrodes 212a and 212b.

Further, in the monolithic ceramic capacitor 210, the shrinkage behavior of the side margin portion 217, the capacitance forming portion 218 and the cover portion 219 at the time of firing is different from each other, so that the capacity forming portion 218 is in the X-axis direction when the unfired element body is fired. Stress tends to concentrate near the ridge R extending to.
Therefore, in the element body 211 after firing, the end portion of the internal electrode 212a near the ridge portion R of the capacitance forming portion 218 may be deformed in the Y-axis direction as shown in FIG.

Further, in the monolithic ceramic capacitor 210, the end portion of the internal electrode 212a near the ridge R in the Y-axis direction is deformed by cutting using a push-cutting blade described later (see step S03 described later) in the manufacturing process. There is.

In the multilayer ceramic capacitor 210, the internal electrodes 212a near the ridge R of the capacitance forming portion 218 are deformed, so that the ends of the internal electrodes 212a come into contact with each other as shown in FIG. 5, which may cause a short circuit failure. ..

On the other hand, in the multilayer ceramic capacitor 10 according to the present embodiment, as shown in FIG. 4, the oxidation regions E1 and E2 are formed at the ends of the internal electrodes 12 and 13. As a result, even if foreign matter or the like adheres to the side surface of the unfired laminated chip in the manufacturing process, conduction between the internal electrodes 12 and 13 via the foreign matter or the like on the side surfaces S1 and S2 of the laminated portion 16 after firing is suppressed. Will be done. Therefore, a short-circuit defect between the internal electrodes 12 and 13 is suppressed.

Further, in the present embodiment, as shown in FIG. 4, the oxidation region E1 in the first portion 18a near the cover portion 19 where the internal electrodes 12 and 13 are easily deformed is wide, and the internal electrodes 12 and 13 are hard to be deformed. The oxidation region E2 in the second portion 18b located near the center of the portion 18 is narrowed.
As a result, in the first portion 18a, the conduction between the internal electrodes 12 and 13 due to the contact between the ends of the adjacent internal electrodes 12 and 13 is effectively suppressed. Therefore, the short circuit failure of the monolithic ceramic capacitor 10 is suppressed.
On the other hand, since the oxidation region E2 in the second portion 18b is narrowed, the capacity loss of the second portion 18b is suppressed. Thereby, the multilayer ceramic capacitor 10 can also secure the capacity.

[Manufacturing method of multilayer ceramic capacitor 10]
FIG. 6 is a flowchart showing a method of manufacturing the monolithic ceramic capacitor 10. FIGS. 7 to 12 are views showing a manufacturing process of the monolithic ceramic capacitor 10. Hereinafter, a method for manufacturing the monolithic ceramic capacitor 10 will be described with reference to FIGS. 7 to 12 with reference to FIGS. 6.

(Step S01: Ceramic sheet preparation process)
In step S01, a first ceramic sheet 101 and a second ceramic sheet 102 for forming the capacitance forming portion 18 and a third ceramic sheet 103 for forming the cover portion 19 are prepared.

The ceramic sheet 103 is a ceramic sheet containing a metal element that forms a composite oxide together with nickel (Ni). In this embodiment, magnesium (Mg) is used as such a metal element. However, when other metal elements such as manganese (Mn) are used, or when two or more kinds of metal elements are used, the same action as described below can be obtained.

In addition to the metal elements as described above, the ceramic sheet 103 includes, for example, aluminum (Al), calcium (Ca), vanadium (V), chromium (Cr), zirconium (Zr), molybdenum (Mo), and tungsten (W). , Tantal (Ta), Niob (Nb), Silicon (Si), Boron (B), Ittrium (Y), Europium (Eu), Gadolinium (Gd), Dysprosium (Dy), Holmium (Ho), Elbium (Er) , Itterbium (Yb), Lithium (Li), Potassium (K), Sodium (Na) and other metal elements may be further contained.

Similarly, the ceramic sheets 101 and 102 also have magnesium (Mg), manganese (Mn), aluminum (Al), calcium (Ca), vanadium (V), chromium (Cr), zirconium (Zr), molybdenum (Mo), and tungsten. (W), Tantal (Ta), Niob (Nb), Silicon (Si), Boron (B), Ittrium (Y), Europium (Eu), Gadolinium (Gd), Dysprosium (Dy), Holmium (Ho), Elbium It may contain metal elements such as (Er), itterbium (Yb), lithium (Li), potassium (K) and sodium (Na).

The ceramic sheets 101, 102, 103 are configured as unfired dielectric green sheets, and are formed into a sheet shape using, for example, a roll coater or a doctor blade.

FIG. 7 is a plan view of the ceramic sheets 101, 102, 103. At this stage, the ceramic sheets 101, 102, and 103 are not separated for each laminated ceramic capacitor 10. FIG. 7 shows cutting lines Lx and Ly for cutting each laminated ceramic capacitor 10. The cutting line Lx is parallel to the X axis, and the cutting line Ly is parallel to the Y axis.

As shown in FIG. 7, the first ceramic sheet 101 is formed with an unfired first internal electrode 112 corresponding to the first internal electrode 12, and the second ceramic sheet 102 is not corresponding to the second internal electrode 13. The second internal electrode 113 for firing is formed. An internal electrode is not formed on the third ceramic sheet 103 corresponding to the cover portion 19.

The first and second internal electrodes 112 and 113 can be formed by using, for example, a conductive paste containing nickel (Ni). For the formation of the first and second internal electrodes 112 and 113 by the conductive paste, for example, a screen printing method or a gravure printing method can be used.

The first and second internal electrodes 112 and 113 are arranged over two regions adjacent to each other in the X-axis direction separated by the cutting line Ly, and extend in a band shape in the Y-axis direction. The first internal electrode 112 and the second internal electrode 113 are displaced in the X-axis direction by one row of regions partitioned by the cutting line Ly. That is, the cutting line Ly passing through the center of the first internal electrode 112 passes through the region between the second internal electrodes 113, and the cutting line Ly passing through the center of the second internal electrode 113 passes through the region between the first internal electrodes 112. Passing through.

(Step S02: Laminating process)
In step S02, the laminated sheet 104 is produced by laminating the ceramic sheets 101, 102, 103 prepared in step S01.

FIG. 8 is a perspective view of the laminated sheet 104 obtained in step S02. In FIG. 8, for convenience of explanation, the ceramic sheets 101, 102, and 103 are shown in an exploded manner. However, in the actual laminated sheet 104, the ceramic sheets 101, 102, 103 are pressure-bonded and integrated by hydrostatic pressure pressurization, uniaxial pressurization, or the like. As a result, a high-density laminated sheet 104 can be obtained.

In the laminated sheet 104, the first ceramic sheet 101 and the second ceramic sheet 102 corresponding to the capacitance forming portion 18 are alternately laminated in the Z-axis direction.
Further, in the laminated sheet 104, the third ceramic sheet 103 corresponding to the cover portion 19 is laminated on the upper and lower surfaces in the Z-axis direction of the first and second ceramic sheets 101 and 102 which are alternately laminated.
A plurality of the third ceramic sheets 103 are laminated within a range in which the total thickness in the Z-axis direction is 15 μm or less. In the example shown in FIG. 8, three third ceramic sheets 103 are laminated, but the number of third ceramic sheets 103 can be changed as appropriate.

(Step S03: Cutting step)
In step S03, the laminated sheet 104 obtained in step S02 is cut with a rotary blade, a push-cutting blade, or the like to produce an unfired laminated chip 116.

FIG. 9 is a plan view of the laminated sheet 104 after step S03. The laminated sheet 104 is cut along the cutting lines Lx and Ly while being fixed to the holding member C. As a result, the laminated sheet 104 is separated into individual pieces, and the laminated chip 116 is obtained. At this time, the holding member C is not cut, and each laminated chip 116 is connected by the holding member C.

FIG. 10 is a diagram showing a state in which the laminated sheet 104 is cut. In FIG. 10, for convenience of explanation, the total number of internal electrodes 112 and 113 is 4, and the total number of ceramic sheets 101, 102 and 103 is 5. However, in reality, more internal electrodes 112, 113 and ceramic sheets 101, 102 are provided.
When the laminated sheet 104 is cut by a cutting blade F such as a push cutting blade, the cutting blade F cutting the laminated sheet 104 drags the internal electrodes 112 and 113, and the ends of the internal electrodes 112 and 113 are shown in FIG. As shown, it may be stretched in the Z-axis direction. As a result, on the side surface of the laminated chip 116, the internal electrodes 112 and 113 may come into contact with each other via the stretched internal electrodes, which may cause a short circuit failure.

However, in the internal electrodes 112 and 113 according to the present embodiment, the oxidation regions E1 and E2 are satisfactorily formed at the ends as shown in FIG. 4 by the firing step described later. Therefore, even if the internal electrodes 112 and 113 are dragged when the laminated sheet 104 is cut and the ends of the internal electrodes 112 and 113 are in contact with each other via the dragged internal electrodes, a short-circuit failure between the internal electrodes 112 and 113 is defective. Is suppressed.

FIG. 11 is a perspective view of the laminated chip 116 obtained in step S03. The laminated chip 116 is formed with an unfired capacity forming portion 118 and a cover portion 119. In the laminated chip 116, unfired first and second internal electrodes 112 and 113 are exposed on both side surfaces S4 and S5 facing the Y-axis direction, which are cut surfaces.

(Step S04: Side margin forming step)
In step S04, the unfired element body 111 is manufactured by providing the unfired side margin portions 117 on the side surfaces S4 and S5 of the laminated chip 116 obtained in step S03.

In step S04, in order to provide the side margin portions 117 on both side surfaces S4 and S5 of the laminated chip 116, the orientation of the laminated chip 116 is appropriately changed by reattaching a holding member such as a tape.
In particular, in step S04, side margin portions 117 are provided on both side surfaces S4 and S5 facing the Y-axis direction, which are the cut surfaces of the laminated chips 116 in step S03. Therefore, in step S04, it is preferable to peel off the laminated chip 116 from the holding member C in advance and rotate the direction of the laminated chip 116 by 90 degrees.

FIG. 12 is a perspective view of the unfired element body 111 obtained by step S04.
The side margin portion 117 is prepared as a ceramic sheet containing magnesium (Mg) as a metal element forming a composite oxide together with nickel (Ni). Similar to the ceramic sheet 103, the metal element used in this ceramic sheet may be manganese (Mn) other than magnesium (Mg).
Next, the side margin portion 117 is attached to the side surfaces S4 and S5 of the laminated chip 116.

In addition to the metal elements as described above, the side margin portion 117 includes, for example, manganese (Mn), aluminum (Al), calcium (Ca), vanadium (V), chromium (Cr), zirconium (Zr), molybdenum (Mo). ), Tungsten (W), Tantal (Ta), Niob (Nb), Silicon (Si), Boron (B), Ittrium (Y), Europium (Eu), Gadolinium (Gd), Dysprosium (Dy), Holmium (Ho) ), Elbium (Er), Itterbium (Yb), Lithium (Li), Potassium (K), Sodium (Na) and other metal elements may be further contained.

The concentration of magnesium (Mg) in the side margin portion 117 according to the present embodiment is equal to or less than the concentration of magnesium (Mg) in the third ceramic sheet 103.

The thickness of the side margin portion 117 is adjusted in the Y-axis direction so as to be 15 μm or less.

In step S04, the side margin portions 117 are not formed into a sheet shape, but are formed by immersing each side surface S4 and S5 of the laminated chip 116 in a paste material made of ceramics containing magnesium (Mg) and pulling it up. May be good.

(Step S05: Firing step)
In step S05, the unfired element 111 obtained in step S04 is fired to produce the element 11 of the multilayer ceramic capacitor 10 shown in FIGS. 1 to 3.
That is, in step S05, the first and second internal electrodes 112 and 113 become the first and second internal electrodes 12 and 13, the laminated chip 116 becomes the laminated portion 16, and the side margin portion 117 becomes the side margin portion 17. ..

The firing temperature of the element body 111 in step S05 can be determined based on the sintering temperature of the laminated chip 116 and the side margin portion 117. For example, when a barium titanate (BaTIO ₃ ) -based material is used as the ceramics, the firing temperature of the element 111 can be about 1000 to 1300 ° C. Further, the calcination can be performed, for example, in a reducing atmosphere or a low oxygen partial pressure atmosphere.

Here, the element body 111 according to the present embodiment is adjusted so that the thickness of the cover portion 119 and the side margin portion 117 is 15 μm or less. As a result, oxygen is easily supplied to the internal electrodes 112 and 113 during firing, and the oxidation regions E1 and E2 are satisfactorily formed at the ends of the internal electrodes 112 and 113.
Therefore, even if foreign matter or the like adheres to the side surfaces S4 and S5 of the laminated chip 116 where the ends of the internal electrodes 112 and 113 are exposed during the manufacturing process, the foreign matter or the like on the side surfaces S1 and S2 of the element body 11 after firing is interposed. The conduction between the internal electrodes 12 and 13 is suppressed. Therefore, a short-circuit defect between the internal electrodes 12 and 13 is suppressed.

Further, in the present embodiment, as described above, the thickness of the cover portion 119 and the side margin portion 117 is adjusted to be 15 μm or less. Therefore, oxygen is supplied not only from the side margin portion 117 side but also from the cover portion 119 side to the vicinity of the ridge portion of the capacitance forming portion 118.
Further, the concentration of magnesium (Mg) in the cover portion 119 is equal to or higher than the concentration of magnesium (Mg) in the side margin portion 117. Therefore, magnesium (Mg) is supplied not only from the side margin portion 117 but also from the cover portion 119 in the vicinity of the ridge portion of the capacitance forming portion 118.

Therefore, when the unfired element 111 is fired, magnesium (Mg) and magnesium (Mg) and more are generated at the ends of the internal electrodes 112 and 113 near the ridge of the capacitance forming portion 118 than at the ends of the other internal electrodes 112 and 113. A lot of oxygen is supplied.

As a result, more composite oxides containing magnesium (Mg) are formed at the ends of the internal electrodes 112 and 113 near the ridge of the capacitance forming portion 118 than at the ends of the other internal electrodes 112 and 113. Therefore, the oxidation region E1 formed at the ends of the internal electrodes 112 and 113 near the ridge of the easily deformable capacitance forming portion 118 becomes wide.

Therefore, in the vicinity of the ridge portion of the capacitance forming portion 18 after firing, the conduction between the internal electrodes 12 and 13 due to the contact between the ends of the adjacent internal electrodes 12 and 13 is effectively suppressed. As a result, short-circuit defects of the monolithic ceramic capacitor 10 are suppressed.

On the other hand, when the unfired element 111 is fired, magnesium (Mg) is contained at the ends of the internal electrodes 112 and 113 near the ridge of the capacitance forming portion 118 more than at the ends of the other internal electrodes 112 and 113. Since a large amount is supplied, the amount of magnesium (Mg) supplied at the ends of the internal electrodes 112 and 113 located near the center of the capacitance forming portion 118 is relatively small.
As a result, the oxidation region E2 formed at the ends of the internal electrodes 12 and 13 located near the center of the capacitance forming portion 18 after firing is narrowed, so that the capacitance loss near the center of the capacitance forming portion 18 is suppressed. .. Therefore, the multilayer ceramic capacitor 10 can also secure the capacity.

(Step S06: External electrode forming step)
In step S06, the multilayer ceramic capacitors 10 shown in FIGS. 1 to 3 are manufactured by forming the first and second external electrodes 14 and 15 on the element body 11 obtained in step S05.

In step S06, first, an unfired electrode material is applied so as to cover one X-axis direction end face of the element body 11, and then an unfired electrode material is applied so as to cover the other X-axis direction end surface of the element body 11. do. The applied unfired electrode material is baked, for example, in a reducing atmosphere or a low oxygen partial pressure atmosphere to form a base film on the element body 11. Then, the intermediate film and the surface film are formed by plating treatment such as electrolytic plating on the base film baked on the element body 11, and the first and second external electrodes 14 and 15 are completed.

In addition, a part of the process in step S06 may be performed before step 05. For example, before step S05, an unfired electrode material is applied to both end faces in the X-axis direction of the unfired element body 111, and in step S05, the unfired element body 111 is sintered and at the same time, the unfired electrode is formed. The material may be baked to form the undercoats of the first and second external electrodes 14, 15.

Hereinafter, examples of the present invention will be described.

[Manufacturing of multilayer ceramic capacitors]
(Preparation of unfired element body)
Samples of unfired elements according to Examples 1 to 6 and Comparative Examples 1 to 4 were prepared according to the above-mentioned production method. The samples according to Examples 1 to 6 and Comparative Examples 1 to 4 differ in the thickness of the cover portion and the side margin portion and the concentrations of manganese and magnesium in the cover portion and the side margin portions. Common.

(Example 1)
In the sample according to the first embodiment, the thickness of the cover portion 119 and the side margin portion 117 are both 15 μm. _{Further, when the barium titanate (BaTIO 3} ) constituting the cover portion 119 and the side margin portion 117 is 100 mol%, the magnesium concentrations of the cover portion 119 and the side margin portion 117 are both 0.48 mol%.

(Example 2)
In the sample according to Example 2, the thickness of the cover portion 119 and the side margin portion 117 are both 15 μm. _{Further, when the barium titanate (BaTIO 3} ) constituting the cover portion 119 and the side margin portion 117 is 100 mol%, the magnesium concentration of the cover portion 119 is 0.96 mol%, and the magnesium of the side margin portion 117 is The concentration is 0.48 mol%.

(Example 3)
In the sample according to Example 3, the thickness of the cover portion 119 and the side margin portion 117 are both 10 μm. _{Further, when the barium titanate (BaTIO 3} ) constituting the cover portion 119 and the side margin portion 117 is 100 mol%, the magnesium concentrations of the cover portion 119 and the side margin portion 117 are both 0.48 mol%.

(Example 4)
In the sample according to Example 4, the thickness of the cover portion 119 and the side margin portion 117 are both 15 μm. _{Further, when the barium titanate (BaTIO 3} ) constituting the cover portion 119 and the side margin portion 117 is 100 mol%, the manganese concentrations in the cover portion 119 and the side margin portion 117 are both 0.48 mol%.

(Example 5)
In the sample according to Example 5, the thickness of the cover portion 119 and the side margin portion 117 are both 15 μm. _{Further, when the barium titanate (BaTiO 3} ) constituting the cover portion 119 and the side margin portion 117 is 100 mol%, the manganese concentration in the cover portion 119 is 0.96 mol%, and the manganese in the side margin portion 117 is The concentration is 0.48 mol%.

(Example 6)
In the sample according to Example 6, the thickness of the cover portion 119 and the side margin portion 117 are both 10 μm. _{Further, when the barium titanate (BaTIO 3} ) constituting the cover portion 119 and the side margin portion 117 is 100 mol%, the manganese concentrations in the cover portion 119 and the side margin portion 117 are both 0.48 mol%.

(Comparative Example 1)
In the sample according to Comparative Example 1, the thickness of both the cover portion and the side margin portion is 20 μm. _{Further, when the barium titanate (BaTIO 3} ) constituting the cover portion and the side margin portion is 100 mol%, the magnesium concentrations in the cover portion and the side margin portion are both 0.48 mol%.

(Comparative Example 2)
In the sample according to Comparative Example 2, the thickness of both the cover portion and the side margin portion is 15 μm. _{Further, when the barium titanate (BaTIO 3} ) constituting the cover portion and the side margin portion is 100 mol%, the magnesium concentration in the cover portion is 0.48 mol%, and the magnesium concentration in the side margin portion is 0. It is 96 mol%.

(Comparative Example 3)
In the sample according to Comparative Example 3, the thickness of both the cover portion and the side margin portion is 20 μm. _{Further, when the barium titanate (BaTIO 3} ) constituting the cover portion and the side margin portion is 100 mol%, the concentration of manganese in both the cover portion and the side margin portion is 0.48 mol%.

(Comparative Example 4)
In the sample according to Comparative Example 4, the thickness of both the cover portion and the side margin portion is 15 μm. _{Further, when the barium titanate (BaTIO 3} ) constituting the cover portion and the side margin portion is 100 mol%, the manganese concentration in the cover portion is 0.48 mol%, and the manganese concentration in the side margin portion is 0. It is 96 mol%.

(Manufacturing of multilayer ceramic capacitors)
Using the unfired elements according to Examples 1 to 6 and Comparative Examples 1 to 4, monolithic ceramic capacitors according to Examples 1 to 6 and Comparative Examples 1 to 4 were produced according to the above manufacturing method.
Table 1 shows the thicknesses of the cover portion and the side margin portion of the unfired element body according to Examples 1 to 6 and Comparative Examples 1 to 4, and the magnesium (Mg) of the cover portion and the side margin portion of the unfired element body. It is a table summarizing the concentration of manganese (Mn) and the dimensions of the oxidation region of the multilayer ceramic capacitors according to Examples 1 to 6 and Comparative Examples 1 to 4.

As shown in Table 1, the monolithic ceramic capacitors according to Comparative Examples 1 to 4 have the same dimensions of the oxidized region near the cover portion and the dimensions of the oxidized region near the center of the capacitance forming portion, whereas the dimensions of the oxidized region are the same. In each of the multilayer ceramic capacitors 10 according to 1 to 6, the dimension of the oxidation region in the vicinity of the cover portion is larger than the dimension of the oxidation region in the vicinity of the center of the capacitance forming portion.

[Evaluation of multilayer ceramic capacitors]
The capacity loss rate and short-circuit rate of the multilayer ceramic capacitors according to Examples 1 to 6 and Comparative Examples 1 to 4 were calculated. At this time, those having a capacity loss rate of 1.5% or less and a short-circuit rate of less than 10% were judged to be acceptable. Table 2 is a table summarizing the results.

The capacity loss rate shown in Table 2 is a reduction rate indicating how much the measured capacity value of the monolithic ceramic capacitor according to Examples 1 to 6 and Comparative Examples 1 to 4 is lower than the design capacity value. be. The design capacitance value is a value calculated from the thickness of the dielectric of each capacitor, the dielectric constant, and the intersecting area of the internal electrodes.
The short-circuit rate shown in Table 2 is 200 pieces according to Examples 1 to 6 and Comparative Examples 1 to 4 under the condition that Osc (Oscillation level) is 0.5 V and a voltage having a frequency of 1 kHz is applied. The ratio of capacitors with short-circuit defects is shown. It should be noted that whether or not a short-circuit defect has occurred in the capacitor was determined using an LCR meter.

Referring to Table 2, the multilayer ceramic capacitors according to Comparative Examples 1 and 3 had a capacitance loss rate of 1.5% or less, but a short circuit rate of 10%. This is because the thickness of the cover portion and the side margin portion of the unfired element is thicker than 15 μm, so that the oxidation of the internal electrode is not promoted and the oxidation region is not sufficiently formed at the end of the internal electrode, resulting in a short circuit. It is presumed that the rate has increased.

Further, the monolithic ceramic capacitors according to Comparative Examples 2 and 4 had a short-circuit rate of less than 10%, but a capacity loss rate of more than 1.5%. This is because the concentration of magnesium (Mg) and manganese (Mn) is higher in the side margin than in the cover, and the end of the internal electrode adjacent to the side margin is excessively oxidized, resulting in capacity loss. It is presumed that the rate has increased.

On the other hand, all of the multilayer ceramic capacitors 10 according to Examples 1 to 6 had a capacity loss rate of 1.5% or less and a short circuit rate of less than 10%. As a result, it was confirmed that the monolithic ceramic capacitor 10 according to Examples 1 to 6 was able to suppress short-circuit defects and secure the capacity at the same time.

From the above, it was experimentally confirmed that the multilayer ceramic capacitor 10 according to the present embodiment manufactured according to the above manufacturing method has a configuration capable of suppressing short-circuit defects and securing a capacity at the same time.

[Other embodiments]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made.

For example, in the monolithic ceramic capacitor 10, the capacitance forming portion 18 may be provided by being divided into a plurality of portions in the Z-axis direction. In this case, it is sufficient that the first and second internal electrodes 12 and 13 are alternately arranged along the Z-axis direction in each capacitance forming portion 18, and the first internal electrode 12 or the first internal electrode 12 or the second is used in the portion where the capacitance forming portion 18 is switched. 2 The internal electrodes 13 may be continuously arranged.

10 ... Multilayer ceramic capacitor 11 ... Elementary body 12 ... 1st internal electrode 13 ... 2nd internal electrode 14 ... 1st external electrode 15 ... 2nd external electrode 16 ... Laminated part 17 ... Side margin part 18 ... Capacity forming part 18a ... Part 1 18b ... Second part 19 ... Cover part 111 ... Unfired element body 116 ... Unfired laminated chips E1, E2 ... Oxidized region

Claims (4)

A capacitance forming portion having a plurality of ceramic layers laminated in the first direction, a plurality of internal electrodes arranged between the plurality of ceramic layers and having a nickel as a main component, and the capacitance forming portion are referred to as the first. A laminated portion having a cover portion covering from the direction, and a laminated portion having
A pair of side margin portions that cover the laminated portion from a second direction orthogonal to the first direction,
Equipped with
The plurality of internal electrodes have a pair of oxidation regions adjacent to the pair of side margin portions and in which manganese is unevenly distributed.
The capacity forming portion is adjacent to the first portion adjacent to the cover portion and the first portion in the first direction, and the dimension of the pair of oxidation regions in the second direction is the first. Consists of a second part, which is smaller than the part of
A laminated ceramic capacitor in which the concentration of manganese over the entire region of the side margin portion in the first direction is smaller than the concentration of manganese in the cover portion. A capacitance forming portion having a plurality of ceramic layers laminated in the first direction, a plurality of internal electrodes arranged between the plurality of ceramic layers and having a plurality of internal electrodes containing nickel as a main component, and the capacitance forming portion are referred to as the first. It does not have a cover portion that is covered from a direction and has a thickness of 15 μm or less in the first direction, and a side surface that faces a second direction orthogonal to the first direction and exposes the plurality of internal electrodes. Make laminated chips for firing,
A side margin portion containing a metal element that forms an oxide together with nickel, the concentration of the metal element is smaller than the concentration of the metal element in the cover portion, and the thickness in the second direction is 15 μm or less. By coating from the second direction, an unfired element body is produced.
A method for manufacturing a multilayer ceramic capacitor that fires the unfired element body. The method for manufacturing a multilayer ceramic capacitor according to claim 2.
By firing the unfired element body, an oxidation region adjacent to the side margin portion and in which the metal element is unevenly distributed is formed on the plurality of internal electrodes.
In the capacitance forming portion, in the first portion adjacent to the cover portion, the dimension of the oxidation region in the second direction is larger than that of the second portion adjacent to the first portion in the first direction. How to make a large monolithic ceramic capacitor. The method for manufacturing a multilayer ceramic capacitor according to claim 2 or 3.
A method for manufacturing a multilayer ceramic capacitor in which the metal element is at least one of magnesium and manganese.

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