JP2020174073A - Multilayer ceramic capacitor - Google Patents

Abstract

To provide a multilayer ceramic capacitor capable of restraining such a problem that tensile stress occurs in the direction of an electric field, between first and second side parts not subjected to impact of the electric field, and an effective layer part subjected to impact of the electric field and deforms, to cause cracking.SOLUTION: A multilayer ceramic capacitor 10 includes a laminate 12 laminating a dielectric layer 14 and an internal electrode 16, and an external electrode 24. The laminate 12 has an effective layer part 13a where internal electrodes 16 face each other in the lamination direction x, a first outer layer part 13b located between an internal electrode 16 closest to a first principal surface 12a and the first principal surface 12a, and a second outer layer part 13c located between an internal electrode 16 closest to a second principal surface 12b and the second principal surface 12b, where the electric strain constant of the first and second outer layer parts 13b, 13c is larger than that of the effective layer part 13a.SELECTED DRAWING: Figure 6

Description

The present invention relates to multilayer ceramic capacitors.

In recent years, many multilayer ceramic capacitors, which are ceramic chip-type electronic components, have been used in electronic devices. Electronic devices that use such multilayer ceramic capacitors are becoming more sophisticated, and along with this, multilayer ceramic capacitors are also rapidly becoming more sophisticated, such as becoming smaller and having a larger capacity. For example, a multilayer ceramic capacitor as in Patent Document 1 is used.

With the above background, ferroelectric materials such as barium titanate, which has a relatively high dielectric constant, are generally used for chip-type electronic components such as multilayer ceramic capacitors.

Japanese Unexamined Patent Publication No. 8-306580

When a voltage is applied to a multilayer ceramic capacitor having a laminate made of such a ferroelectric material, strain is generated in the laminate according to the magnitude of the applied voltage along the electric field direction due to the electrolytic distortion phenomenon, and the machine Displacement occurs. When the electrostriction phenomenon occurs in this way, stress is generated inside the monolithic ceramic capacitor.

The stress generated inside the multilayer ceramic capacitor is generated between the effective layer portion that is deformed by the influence of the electric field and the outer peripheral portion consisting only of the dielectric layer that is not affected by the electric field. The outer peripheral portion is an effective layer portion in which the internal electrodes face each other, a first outer layer portion located between the internal electrode closest to the first main surface of the laminated body and the first main surface, and the laminated body. The second outer layer portion located between the internal electrode closest to the second main surface and the second main surface, and the first side of the laminate located between the effective layer portion and the first side surface. A portion and a second side portion of the laminate located between the effective layer portion and the second side surface are shown.

Here, in particular, tensile stress is generated along the direction of the electric field between the first side portion and the second side portion that are not affected by the electric field and the effective layer portion that is deformed under the influence of the electric field. It can lead to cracks.

Therefore, an object of the present invention is to provide a multilayer ceramic capacitor capable of suppressing the above problems.

The laminated ceramic capacitor according to the present invention includes a plurality of laminated dielectric layers and a plurality of laminated internal electrodes, and has a first main surface and a second main surface facing the stacking direction and a stacking direction. A laminate including a first side surface and a second side surface opposite to each other in the width direction orthogonal to each other, and a first end surface and a second end surface facing each other in the length direction orthogonal to the stacking direction and the width direction, and the inside. The electrode has a first internal electrode exposed to the first end face and a second internal electrode exposed to the second end face, is connected to the first internal electrode, and is at least on the first end face. It has a first external electrode to be arranged and a second external electrode connected to the second internal electrode and arranged on at least the second end face, and the laminate comprises the first main surface and In the stacking direction connecting the second main surfaces, the effective layer portion in which the internal electrodes face each other and the first outer layer portion located between the internal electrode closest to the first main surface and the first main surface. And a second outer layer portion located between the inner electrode closest to the second main surface and the second main surface, and the electric strain constants of the first outer layer portion and the second outer layer portion. Is larger than the electric strain constant of the effective layer portion.

In the present invention, the electric strain constants of the first outer layer portion and the second outer layer portion are made larger than the electric strain constants of the effective layer portion, so that the effective layer portion is formed in the first outer layer portion and the second outer layer portion. Since the elongation of the electric strain occurs in the direction of suppressing the elongation due to the electric strain in the thickness direction, it is possible to suppress the mechanical displacement due to the electric strain in the effective layer portion. As a result, it is possible to suppress the tensile stress between the first side portion and the second side portion that are not affected by the electric field and the effective layer portion that is deformed by the influence of the electric field. Therefore, cracks generated in the laminated body between the effective layer portion and the first side portion and the second side portion of the laminated body can be suppressed.

According to the present invention, a tensile stress is applied along the direction of the electric field between the first side portion and the second side portion which are not affected by the electric field and the effective layer portion which is deformed by the influence of the electric field. It is possible to provide a monolithic ceramic capacitor capable of suppressing the problem of causing cracks.

The above-mentioned object, other object, feature and advantage of the present invention will be further clarified from the description of the embodiment for carrying out the following invention with reference to the drawings.

It is an external perspective view which shows an example of the multilayer ceramic capacitor which concerns on this invention. It is a front view which shows an example of the multilayer ceramic capacitor which concerns on this invention. FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 1 showing a multilayer ceramic capacitor according to the present invention. It is sectional drawing in the IV-IV line of FIG. 1 which shows the multilayer ceramic capacitor which concerns on this invention. (A) It is a schematic diagram in the LT direction of the multilayer ceramic capacitor which concerns on this invention. (B) It is a schematic diagram in the WT direction of the multilayer ceramic capacitor which concerns on this invention. It is a schematic diagram which shows the direction of tensile stress and the direction which electric strain occurs when an electric field is applied to the effective layer part in the multilayer ceramic capacitor which concerns on this invention. (A) It is a figure which shows the structure which the counter electrode part of the internal electrode of the laminated body in the laminated ceramic capacitor which concerns on this invention is divided into two. (B) It is a figure which shows the structure which the counter electrode part of the internal electrode of the laminated body in the laminated ceramic capacitor which concerns on this invention is divided into three. (C) It is a figure which shows the structure which the counter electrode part of the internal electrode of the laminated body in the laminated ceramic capacitor which concerns on this invention is divided into four.

1. 1. Multilayer Ceramic Capacitor Hereinafter, the monolithic ceramic capacitor according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an external perspective view showing an example of a multilayer ceramic capacitor according to the present invention. FIG. 2 is a front view showing an example of a multilayer ceramic capacitor according to the present invention. FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 1 showing a multilayer ceramic capacitor according to the present invention. FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 1 showing a multilayer ceramic capacitor according to the present invention. FIG. 5A is a schematic view of the multilayer ceramic capacitor according to the present invention in the LT direction. FIG. 5B is a schematic view of the multilayer ceramic capacitor according to the present invention in the WT direction. FIG. 6 is a schematic view showing the direction of tensile stress and the direction in which electric strain occurs when an electric field is applied to the effective layer portion in the multilayer ceramic capacitor according to the present invention. FIG. 7A is a diagram showing a structure in which the counter electrode portion of the internal electrode of the laminated body in the multilayer ceramic capacitor according to the present invention is divided into two. FIG. 7B is a diagram showing a structure in which the counter electrode portion of the internal electrode of the laminated body of the multilayer ceramic capacitor according to the present invention is divided into three parts. FIG. 7C is a diagram showing a structure in which the counter electrode portion of the internal electrode of the laminated body of the multilayer ceramic capacitor according to the present invention is divided into four parts.

As shown in FIGS. 1 to 4, the multilayer ceramic capacitor 10 according to the present embodiment includes the laminate 12, the first external electrode 24a and the second external electrode 24b (2) formed on the surface of the laminate 12. A pair of external electrodes).

(Laminated body 12)
The laminated body 12 includes a plurality of laminated dielectric layers 14 and a plurality of internal electrodes 16, and is orthogonal to the first main surface 12a and the second main surface 12b facing the stacking direction x and the stacking direction x. The first side surface 12c and the second side surface 12d facing the width direction y, and the first end surface 12e and the second end surface 12f facing the length direction z orthogonal to the stacking direction x and the width direction y. including.

The first main surface 12a and the second main surface 12b of the laminated body 12 refer to surfaces parallel to the surface on which the multilayer ceramic capacitor 10 is mounted (hereinafter, referred to as “mounting surface”, not shown). In particular, the second main surface 12b is a surface that is actually mounted on the mounting surface.

Further, it is preferable that the laminated body 12 has rounded corners and ridges. The corner portion is a portion where three adjacent surfaces of the laminated body 12 intersect, and the ridge portion is a portion where two adjacent surfaces of the laminated body 12 intersect. Further, unevenness or the like is formed on a part or the whole of the first main surface 12a and the second main surface 12b, the first side surface 12c and the second side surface 12d, and the first end surface 12e and the second end surface 12f. It may have been.

As shown in FIGS. 5A and 5B, the laminated body 12 has a first inner surface, which will be described later, in a stacking direction x connecting the first main surface 12a and the second main surface 12b of the laminated body 12. An effective layer portion 13a on which the electrodes 16a and the second internal electrode 16b face each other, and a first outer layer portion 13b located between the internal electrode 16 closest to the first main surface 12a and the first main surface 12a. , Located between the second outer layer portion 13c located between the internal electrode 16 closest to the second main surface 12b and the second main surface 12b, and between the effective layer portion 13a and the first side surface 12c. The first side portion 13d, the second side portion 13e located between the effective layer portion 13a and the second side surface 12d, and the second side portion 13a located between the effective layer portion 13a and the first end surface 12e. A second end portion 13f including the extraction electrode portion 20a of the internal electrode 1 and a second end portion 13a located between the effective layer portion 13a and the second end surface 12f and including the extraction electrode portion 20b of the second internal electrode. It has an end portion of 13 g. The outer peripheral portion has a first outer layer portion 13b composed of a dielectric layer, a second outer layer portion 13c, a first side portion 13d, and a second side portion 13e.

A plurality of first outer layer portions 13b are located on the first main surface 12a side of the laminated body 12 and are located between the first main surface 12a and the internal electrode 16 closest to the first main surface 12a. It is an aggregate of the dielectric layers 14 of.

The second outer layer portion 13c is a plurality of sheets located on the second main surface 12b side of the laminated body 12 and located between the second main surface 12b and the internal electrode 16 closest to the second main surface 12b. It is an aggregate of the dielectric layers 14 of.

The region sandwiched between the first outer layer portion 13b and the second outer layer portion 13c is the effective layer portion 13a.

The electric strain constants of the first outer layer portion 13b and the second outer layer portion 13c are larger than the electric strain constants of the effective layer portion 13a. As a result, the mechanical displacement of the first outer layer portion 13b and the second outer layer portion 13c becomes large, and in the first outer layer portion 13b and the second outer layer portion 13c, as shown in FIG. 6, the effective layer portion 13a Since the elongation of the electric strain occurs in the direction of suppressing the elongation due to the electric strain in the thickness direction (arrow 30) (arrow 40), it is possible to suppress the mechanical displacement due to the electric strain in the effective layer portion 13a. As a result, it is possible to suppress the tensile stress between the first side portion 13d and the second side portion 13e that are not affected by the electric field and the effective layer portion 13a that is deformed under the influence of the electric field. .. Therefore, cracks generated in the laminated body 12 between the effective layer portion 13a and the first side portion 13d and the second side portion 13e of the laminated body 12 can be suppressed.

Here, in the multilayer ceramic capacitor 10, the electrostrain constants of the effective layer portion 13a, the first outer layer portion 13b, and the second outer layer portion 13c are expressed as follows.

(Number 1)
Q ₁₁ = (ε ² * E ² ) / x ₁
Here, x ₁ is the amount of strain in the electric field direction.

(Number 2)
Q ₁₂ = (ε ² * E ² ) / x ₂
Here, x ₂ is the amount of strain in the direction perpendicular to the electric field.

The electrolytic strain constants of the first outer layer portion 13b and the second outer layer portion 13c represented by the above equation are such that Q ₁₁ is 0.05 m ⁴ C ^-2 or more and 0.20 m ⁴ C ^-2 or less, and | Q ₁₂ | is 0.02 m ⁴ C ^-2 least 0.09 m ⁴ is preferably C ^-2 or less, electrostriction constant of the effective layer portion 13a is, Q ₁₁ is 0.03 m ⁴ C ^-2 least 0.05 m ⁴ C ^-2 or less, | Q ₁₂ | it is preferably 0.01 m ⁴ C ^-2 least 0.06 m ⁴ C ^-2 or less. The difference in electrostrain constant between the materials of the first outer layer portion 13b and the second outer layer portion 13c and the material of the effective layer portion 13a is that Q ₁₁ is 0.02 m ⁴ C ^-2 or more and 0.15 m ⁴ C. ^-2, | Q ₁₂ | it is preferably 0.01 m ⁴ C ^-2 least 0.03 m ⁴ C ^-2. As a result, the mechanical displacement of the first outer layer portion 13b and the second outer layer portion 13c is increased, and the force for suppressing the mechanical displacement of the first side portion 13d and the second side portion 13e is increased, which is effective. It is possible to obtain the effect of suppressing cracks between the layer portion 13a, the first outer layer portion 13b, and the second outer layer portion 13c.

(Dielectric layer 14)
As the dielectric material of the dielectric layer 14, for example, it can be used a dielectric ceramic containing a component such as BaTiO _3, CaTiO _3, SrTiO ₃ or CaZrO _3,. Further, those to which a component having a content smaller than that of the main component such as Mn compound, Fe compound, Cr compound, Co compound and Ni compound is added may be used.

The number of the dielectric layers 14 is preferably 10 or more and 2000 or less including the first outer layer portion 13b and the second outer layer portion 13c. The thickness of the dielectric layer 14 is preferably 0.5 μm or more and 10 μm or less.

(Internal electrode 16)
The internal electrodes 16 are alternately laminated with the plurality of dielectric layers 14, and the plurality of first internal electrodes 16a exposed on the first end surface 12e are alternately laminated with the plurality of dielectric layers 14, and the second It has a plurality of second internal electrodes 16b exposed on the end face 12f.

The first internal electrode 16a is a first opposed electrode portion 18a that faces the second internal electrode 16b and is drawn from the first counter electrode portion 18a to the first end surface 12e of the laminated body 12. It is provided with a drawer electrode portion 20a. The end of the first lead-out electrode portion 20a of the first internal electrode 16a is drawn out to the surface of the first end surface 12e of the laminated body 12 to form an exposed portion.

The second internal electrode 16b is a second opposed electrode portion 18b that faces the first internal electrode 16a and is drawn from the second counter electrode portion 18b to the second end surface 12f of the laminated body 12. It is provided with a drawer electrode portion 20b. The end of the second extraction electrode portion 20b of the second internal electrode 16b is drawn out to the surface of the second end surface 12f of the laminated body 12, forming an exposed portion.

The counter electrode portion 18 is composed of a first counter electrode portion 18a of the first internal electrode 16a and a second counter electrode portion 18b of the second internal electrode 16b. The shapes of the first counter electrode portion 18a and the second counter electrode portion 18b are not particularly limited, but are preferably rectangular. However, the corners of the first counter electrode portion 18a and the second counter electrode portion 18b may be rounded or may be formed diagonally in a tapered shape, for example.

The extraction electrode portion 20 is composed of a first extraction electrode portion 20a of the first internal electrode 16a and a second extraction electrode portion 20b of the second internal electric power 16b. The shapes of the first extraction electrode portion 20a and the second extraction electrode portion 20b are not particularly limited, but are preferably rectangular. However, the corners of the first extraction electrode portion 20a and the second extraction electrode portion 20b may be rounded or may be formed diagonally in a tapered shape, for example.

The width of the first counter electrode portion 18a of the first internal electrode 16a and the second counter electrode portion 18b of the second internal electrode 16b, and the first extraction electrode portion 20a and the second of the first internal electrode 16a. The width of the second extraction electrode portion 20b of the internal electrode 16b of the above may be the same width, or one of them may be formed to have a narrow width.

Further, in the laminated body 12, the first internal electrode 16a and the second internal electrode 16b, the first internal electrode 16a and the second internal electrode 16b face each other, and the first facing electrode portion 18a and the second facing electrode portion 18a and the second facing electrode portion 18a and the second facing electrode portion 18a and the second facing electrode portion 18a Side portion 22a (W gap portion) of the laminated body 12 located between the electrode portion 18b, the first counter electrode portion 18a and the second counter electrode portion 18b, and the first side surface 12c and the second side surface 12d. The first internal electrode 16a and the second internal electrode 16b are located between the first counter electrode portion 18a and the second counter electrode portion 18b and the first end surface 12e and the second end surface 12f. It includes an end portion 22b (L gap portion) of the laminated body 12 including either one of the first extraction electrode portion 20a and the second extraction electrode portion 20b.

Further, as shown in FIG. 7, the internal electrode 16 is provided with a floating internal electrode 16c that is not drawn out to either the first end surface 12e or the second end surface 12f, and is opposed by the floating internal electrode 16c. The electrode portion 18 may be divided into a plurality of structures. For example, it has a double structure (see FIG. 7 (a)), a triple structure (see FIG. 7 (b)), and a quadruple structure (see FIG. 7 (c)). Needless to say, the structure may be four or more. In this way, by forming the counter electrode portion 18 into a plurality of divided structures, a plurality of capacitor components are formed between the opposing internal electrodes 16, and these capacitor components are connected in series. Therefore, the voltage applied to each capacitor component becomes low, and the withstand voltage of the multilayer ceramic capacitor 10 can be increased.

The first internal electrode 16a and the second internal electrode 16b are appropriately used, for example, a metal such as Ni, Cu, Ag, Pd, Au, or an alloy containing at least one of these metals such as an Ag-Pd alloy. It can be made of a conductive material of.

In the present embodiment, the first counter electrode portion 18a and the second counter electrode portion 18b face each other via the dielectric layer 14 to form a capacitance, and the characteristics of the capacitor are exhibited.

The thickness of each of the first internal electrode 16a and the second internal electrode 16b is preferably, for example, 0.2 μm or more and 2.0 μm or less. The number of internal electrodes 16 is not particularly limited, but is preferably 10 or more and 2000 or less.

(External electrode 24)
The external electrode 24 has a first external electrode 24a and a second external electrode 24b.

The first external electrode 24a is electrically connected to the first internal electrode 16a and is arranged on the first end surface 12e and at least a part on the second main surface 12b to be mounted on the mounting surface. Has been done. Further, the second external electrode 24b is electrically connected to the second internal electrode 16b and is a part on the second end surface 12f and at least a part on the second main surface 12b to be mounted on the mounting surface. Is located in.

The first external electrode 24a has a first base electrode layer 26a containing a conductive metal arranged on the laminated body 12, and is arranged so as to cover the first base electrode layer 26a. It has a plating layer 28a of. Further, the second external electrode 24b has a second base electrode layer 26b containing a conductive metal arranged on the laminated body 12, and is arranged so as to cover the second base electrode layer 26b. It has a second plating layer 28b.

The first base electrode layer 26a and the second base electrode layer 26b include at least one selected from a baking layer, a conductive resin layer, a thin film layer, and the like.

The baking layer contains a glass component and a metal. The glass component of the baking layer contains at least one selected from B, Si, Ba, Mg, Al, Li and the like. The metal of the baking layer contains, for example, at least one selected from Cu, Ni, Ag, Pd, Ag—Pd alloy, Au and the like. The baking layer may be a plurality of layers.

The baking layer is formed by applying a conductive paste containing glass and metal to the laminate 12 and baking it, and may be baked at the same time as the internal electrode 16 or may be baked after the internal electrode 16 is fired.

The thickness of the first baking layer and the second baking layer at the center of the first base electrode layer 26a and the second base electrode layer 26b located on the first end face 12e and the second end face 12f in the stacking direction x. Is preferably, for example, 15 μm or more and 300 μm or less. Further, when the base electrode layer 26 is provided on the first main surface 12a and the second main surface 12b, the first side surface 12c and the second side surface 12d, the first main surface 12a and the second main surface 12a and the second main surface are provided. The first baking layer and the first baking layer in the central portion in the length direction z, which are the first base electrode layer 26a and the second base electrode layer 26b located on the surface 12b, the first side surface 12c and the second side surface 12d. The thickness of the baking layer of No. 2 is preferably, for example, 5 μm or more and 60 μm or less.

The conductive resin layer contains a thermosetting resin and a metal. The conductive resin layer may be a plurality of layers. The conductive resin layer may be arranged on the baking layer so as to cover the baking layer, or may be arranged directly on the laminated body 12.

As the thermosetting resin of the conductive resin layer, for example, various known thermosetting resins such as epoxy resin, phenol resin, urethane resin, silicone resin, and polyimide resin can be used. Among them, epoxy resin having excellent heat resistance, moisture resistance, adhesion and the like is one of the most suitable resins.

The thermosetting resin contained in the conductive resin layer is preferably contained in an amount of 25 vol% or more and 65 vol% or less with respect to the total volume of the conductive resin.

Further, the conductive resin layer preferably contains a curing agent together with the thermosetting resin. When an epoxy resin is used as the base resin, various known compounds such as phenol-based, amine-based, acid anhydride-based, and imidazole-based compounds can be used as the curing agent for the epoxy resin.

The metal contained in the conductive resin layer mainly bears the electrical conductivity of the conductive resin layer. Specifically, when the metals contained in the conductive resin layer come into contact with each other, an energization path is formed inside the conductive resin layer.

The shape of the metal contained in the conductive resin layer is not particularly limited. As the metal contained in the conductive resin layer, a spherical metal, a flat metal, or the like can be used, but it is preferable to use a mixture of the spherical metal powder and the flat metal powder. Further, the average particle size of the metal contained in the conductive resin layer is not particularly limited. The average particle size of the metal contained in the conductive resin layer may be, for example, 0.3 μm or more and 10 μm or less.

As the metal contained in the conductive resin layer, Ag, Cu, or an alloy thereof can be used. Further, a metal powder having an Ag coating on the surface can be used. When an Ag-coated metal powder is used, it is preferable to use Cu or Ni as the metal powder. Further, it is also possible to use Cu which has been subjected to an antioxidant treatment.

The reason for using Ag conductive metal powder as the metal of the conductive resin layer is that Ag is suitable as an electrode material because it has the lowest specific resistance among metals, and since Ag is a noble metal, it does not oxidize and has weather resistance. Because it is expensive. The reason for using the Ag-coated metal is that the metal of the base material can be made inexpensive while maintaining the above-mentioned characteristics of Ag.

The metal contained in the conductive resin layer is preferably contained in an amount of 35 vol% or more and 75 vol% or less with respect to the total volume of the conductive resin.

The first conductive resin layer and the second conductivity in the central portion of the first base electrode layer 26a and the second base electrode layer 26b located on the first end face 12e and the second end face 12f in the stacking direction x. The thickness of the resin layer is preferably, for example, 10 μm or more and 200 μm or less. Further, when the base electrode layer 26 is provided on the first main surface 12a and the second main surface 12b, the first side surface 12c and the second side surface 12d, the first main surface 12a and the second main surface 12a and the second main surface are provided. The first conductive resin layer in the central portion in the length direction z, which is the first base electrode layer 26a and the second base electrode layer 26b located on the surface 12b, the first side surface 12c and the second side surface 12d. The thickness of the second conductive resin layer is preferably 5 μm or more and 50 μm or less, for example.

Since the conductive resin layer contains a thermosetting resin, it is more flexible than the base electrode layer 26 made of, for example, a plating film or a fired product of a conductive paste. Therefore, even when a physical impact or an impact due to a thermal cycle is applied to the multilayer ceramic capacitor 10, the conductive resin layer functions as a buffer layer to prevent cracks in the multilayer ceramic capacitor 10. Can be done.

The thin film layer is a layer having a thickness of 1 μm or less formed by a thin film forming method such as a sputtering method or a thin film deposition method and having metal particles deposited therein.

(Plating layer 28)
The plating layer 28 has a first plating layer 28a and a second plating layer 28b. The first plating layer 28a is arranged so as to cover the first base electrode layer 26a. The second plating layer 28b is arranged so as to cover the second base electrode layer 26b.

The plating layer 28 includes, for example, at least one selected from Cu, Ni, Ag, Pd, Ag—Pd alloy, Au and the like.

The plating layer 28 may be formed of a plurality of layers. A two-layer structure consisting of a Ni plating layer and a Sn plating layer is preferable. The Ni plating layer can prevent the base electrode layer 26 from being eroded by the solder when mounting the multilayer ceramic capacitor 10, and the Sn plating layer has the wettability of the solder when mounting the multilayer ceramic capacitor 10. Can be improved and easily implemented.

The thickness of the plating layer 28 per layer is preferably 2 μm or more and 15 μm or less.

The external electrode 24 may be formed only by the plating layer 28 without providing the base electrode layer 26.
Hereinafter, a structure in which the plating layer 28 is provided without providing the base electrode layer 26 will be described.

Each of the first external electrode 24a and the second external electrode 24b may not be provided with the base electrode layer 26, and the plating layer 28 may be directly formed on the surface of the laminated body 12. That is, the multilayer ceramic capacitor 10 may have a structure including a plating layer 28 electrically connected to the first internal electrode 16a or the second internal electrode 16b. In such a case, the plating layer 28 may be formed after the catalyst is arranged on the surface of the laminated body 12 as a pretreatment.

The plating layer 28 preferably includes a lower layer plating layer formed on the surface of the laminated body 12 and an upper layer plating layer formed on the surface of the lower layer plating layer.

The lower plating layer and the upper plating layer preferably contain, for example, at least one metal selected from Cu, Ni, Sn, Pb, Au, Ag, Pd, Bi, Zn, and the like, or an alloy containing the metal.

The lower plating layer is preferably formed using Ni having solder barrier performance, and the upper plating layer is preferably formed using Sn or Au having good solder wettability.

Further, for example, when the first internal electrode 16a and the second internal electrode 16b are formed using Ni, the lower plating layer is preferably formed using Cu having good bondability with Ni. The upper plating layer may be formed as needed, and the first external electrode 24a and the second external electrode 24b may each be composed of only the lower plating layer.

In the plating layer 28, the upper plating layer may be the outermost layer, or another plating layer may be formed on the surface of the upper plating layer.

In a structure in which the plating layer 28 is provided without providing the base electrode layer 26, the thickness of the plating layer 28 per layer is preferably 1 μm or more and 15 μm or less.

The plating layer 28 preferably does not contain glass. The metal ratio per unit volume of the plating layer 28 is preferably 99 vol% or more.

The dimensions of the length direction z of the laminated ceramic capacitor 10 includes a layered body 12 and the external electrodes 24 and L _M dimensions. L _M size is preferably 0.2mm or more 10.0mm or less. The dimension in the width direction y of the multilayer ceramic capacitor 10 includes a layered body 12 and the external electrodes 24 and W _M dimensions. W _M size is preferably 0.1mm or more 5.0mm or less. The dimension of the laminated ceramic capacitor 10 including the laminated body 12 and the external electrode 24 in the stacking direction x is defined as the _TM dimension. T _M size is preferably 0.1mm or more 5.0mm or less.

2. Method for Manufacturing Multilayer Ceramic Capacitor Next, a method for manufacturing the monolithic ceramic capacitor 10 according to the present invention will be described.

First, a dielectric sheet and a conductive paste for internal electrodes are prepared. The conductive paste for the dielectric sheet and the internal electrode contains a binder and a solvent, and known organic binders and organic solvents can be used.

At this time, the dielectric sheet is prepared so as to have a relationship of the electric strain constants of the first outer layer portion 13b, the second outer layer portion 13c, and the effective layer portion 13a. The electrostrain constant can be adjusted by controlling the composition of barium titanate. In the embodiment of the present invention, the amount of Ca added to barium titanate was adjusted to control the electric strain constants of the first outer layer portion 13b, the second outer layer portion 13c, and the effective layer portion 13a.

Next, the conductive paste for the internal electrode is printed on the dielectric sheet for the effective layer portion 13a in a predetermined pattern by, for example, screen printing or gravure printing to form the internal electrode pattern.

Next, a predetermined number of dielectric sheets for the first outer layer portion 13b and the second outer layer portion 13c on which the internal electrode pattern is not printed are laminated, and the dielectric sheets on which the internal electrode pattern is printed are sequentially laminated. The laminated sheets are laminated, and a predetermined number of dielectric sheets for the first outer layer portion 13b and the second outer layer portion 13c are laminated on the laminated sheets to prepare a laminated sheet.

Next, the laminated sheet is pressed in the lamination direction x by means such as a hydrostatic press to prepare a laminated block.

Next, the laminated block is cut to a predetermined size, and the laminated chip is cut out. At this time, the corners and ridges of the laminated chips may be rounded by barrel polishing or the like.

Next, the laminated chips are fired to produce a laminated body 12. The firing temperature depends on the material of the dielectric layer 14 and the internal electrode 16, but is preferably 900 ° C. or higher and 1400 ° C. or lower.

Next, the external electrode 24 is formed on the laminated body 12. A baking layer may be formed, and a plating layer 28 may be formed on the surface of the baking layer. Further, the plating layer 28 may be formed directly on the surface of the laminated body 12 without providing the baking layer.

When a baking layer is formed as the base electrode layer 26, the conductive paste for the external electrode 24 is applied to both end surfaces of the laminated body 12 and baked to form the baking layer as the base electrode layer 26 of the external electrode 24. In the embodiment of the present invention, a baking layer is formed as the base electrode layer 26. A conductive paste containing a glass component and a metal is applied by a method such as dipping, and then a baking process is performed to form a base electrode layer. The temperature of the baking process at this time is preferably 700 ° C. or higher and 900 ° C. or lower.

When the conductive resin layer is formed as the base electrode layer 26, the conductive resin layer can be formed by the following method. The conductive resin layer may be formed on the surface of the baking layer, or the conductive resin layer may be formed directly on the laminated body 12 by itself without forming the baking layer.

As a method for forming the conductive resin layer, a conductive resin paste containing a thermosetting resin and a metal component is applied on a baking layer or a laminate, and heat treatment is performed at a temperature of 250 ° C. or higher and 550 ° C. or lower to obtain the resin. It is thermoset to form a conductive resin layer. The atmosphere during the heat treatment at this time is preferably an N ₂ atmosphere. Further, in order to prevent the resin from scattering and to prevent the oxidation of various metal components, the oxygen concentration is preferably suppressed to 100 ppm or less.

When the conductive resin layer is formed as the base electrode layer 26, the base electrode layer can be formed by a thin film forming method such as a sputtering method or a thin film deposition method. The base electrode layer 26 formed of the thin film layer is a layer of 1 μm or less in which metal particles are deposited.

Further, the plating layer 28 may be provided on the exposed portion of the internal electrode 16 of the laminated body 12 without providing the base electrode layer 26. In that case, it can be formed by the following method.

The first end face 12e and the second end face 12f of the laminate 12 are plated to form a base plating film on the exposed portion of the internal electrode 16. Either electrolytic plating or electroless plating may be used for the plating treatment, but electroless plating requires pretreatment with a catalyst or the like in order to improve the plating precipitation rate, which complicates the process. There is a demerit. Therefore, it is usually preferable to use electrolytic plating. As the plating method, it is preferable to use barrel plating. Further, if necessary, the upper layer plating electrode formed on the surface of the lower layer plating electrode may be similarly formed.

After that, the plating layer 28 is formed on the surface of the base electrode layer 26, the surface of the conductive resin layer, the surface of the base plating layer, and the surface of the upper plating layer. In this embodiment, a Ni plating layer and a Sn plating layer are formed on the baking layer. The Ni plating layer and the Sn plating layer are sequentially formed by, for example, a barrel plating method.

As described above, the monolithic ceramic capacitor 10 according to this embodiment is manufactured.

With the above configuration, in the present invention, the electric strain constants of the first outer layer portion 13b and the second outer layer portion 13c are made larger than the electric strain constants of the effective layer portion 13a, so that the first outer layer portion 13b and the first outer layer portion 13b and the first outer layer portion 13b In the outer layer portion 13c of 2, the elongation of the effective layer portion 13a due to the electric strain in the thickness direction is suppressed, so that the mechanical displacement of the effective layer portion 13a due to the electric strain can be suppressed. Become. As a result, it is possible to suppress the tensile stress between the first side portion 13d and the second side portion 13e that are not affected by the electric field and the effective layer portion 13a that is deformed under the influence of the electric field. .. Therefore, it is possible to suppress cracks generated in the laminated body between the effective layer portion 13a and the first side portion 13d and the second side portion 13e of the laminated body 12.

Therefore, tensile stress is generated along the direction of the electric field between the first side portion 13d and the second side portion 13e that are not affected by the electric field and the effective layer portion 13a that is deformed under the influence of the electric field. It is possible to provide a multilayer ceramic capacitor 10 capable of suppressing the problem of cracking.

The present invention is not limited to the above-described embodiment, and is variously modified within the scope of the gist thereof.

10 Multilayer ceramic capacitor 12 Laminated body 12a First main surface 12b Second main surface 12c First side surface 12d Second side surface 12e First end surface 12f Second end surface 13a Effective layer part 13b First outer layer part 13c Second outer layer part 13d First side part 13e Second side part 13f First end part 13g Second end part 14 Dielectric layer 16 Internal electrode 16a First internal electrode 16b Second internal electrode 16c Floating Internal electrode 18 Counter electrode part 18a First counter electrode part 18b Second counter electrode part 20 Draw-out electrode part 20a First lead-out electrode part 20b Second lead-out electrode part 22a W gap part 22b L gap part 24 External electrode 24a 1st external electrode 24b 2nd external electrode 26 Base electrode layer 26a 1st base electrode layer 26b 2nd base electrode layer 28 Plating layer 28a 1st plating layer 28b 2nd plating layer 30 Arrow (effective layer part) Distortion direction)
40 Arrow (distortion direction of the first and second outer layers)
x Lamination direction y Width direction z Length direction L Length in the length direction of the laminate W Length in the width direction of the laminate T Length in the lamination direction of the laminate L _M Length in the length direction of the laminated ceramic electronic component It is W _M length of the stacking direction of the width direction of the length T _M multilayer ceramic electronic component of a multilayer ceramic electronic component

Claims (3)

A first main surface and a second main surface that include a plurality of laminated dielectric layers and a plurality of laminated internal electrodes and face each other in the stacking direction and a first surface that faces the width direction orthogonal to the stacking direction. A laminate including the side surfaces and the second side surface, and the first end face and the second end face facing each other in the length direction orthogonal to the stacking direction and the width direction.
The internal electrode has a first internal electrode exposed to the first end face and a second internal electrode exposed to the second end face.
With a first external electrode connected to the first internal electrode and disposed at least on the first end face.
With the second external electrode connected to the second internal electrode and arranged at least on the second end face,
Have,
The laminated body includes an effective layer portion in which the internal electrodes face each other in the stacking direction connecting the first main surface and the second main surface, and the internal electrode closest to the first main surface. A first outer layer portion located between the first main surface and a second outer layer portion located between the internal electrode closest to the second main surface and the second main surface. ,
Have,
A monolithic ceramic capacitor in which the electric strain constants of the first outer layer portion and the second outer layer portion are larger than the electric strain constants of the effective layer portion. The electrostrictive constant of the first outer layer portion and the second outer portion, Q ₁₁ is 0.05 m ⁴ C ^-2 least 0.20 m ⁴ C ^-2 or less, | Q ₁₂ | is 0.02 m ⁴ C ^{- 2} above 0.09m is ⁴ C ^-2 or less, multilayer ceramic capacitor according to claim 1. The difference in the electrostriction constant between the material of the first outer layer portion and the second outer layer portion and the material of the effective layer portion is that Q ₁₁ is 0.02 m ⁴ C- ² or more and 0.15 m ⁴ C ^-2. hereinafter, | Q ₁₂ | is 0.01 m ⁴ C ^-2 least 0.03 m ⁴ C ^-2 or less, multilayer ceramic capacitor according to claim 1 or claim 2.

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