JP7269736B2 - Ceramic electronic component and manufacturing method thereof - Google Patents

Description

The present invention relates to ceramic electronic components and methods of manufacturing the same.

In ceramic electronic components such as laminated ceramic capacitors, the proportion of internal electrode layers is increasing as dielectric layers become thinner and more multilayered. Nickel (Ni), which is the main component of the internal electrode layer, reacts with barium titanate (BaTiO ₃ ), which is the main phase of the dielectric layer, to promote sintering of BaTiO ₃ . and promotes sintering of the dielectric layer.

As a result, the internal/external difference in sintering (the internal/external difference in sintering speed) can become a problem. Specifically, there is a difference in the sintering speed between the capacitance generating portion (active region) in which the Ni internal electrodes are densely stacked and the protection region (cover and side margins), and the sinterability of the active region is sufficiently high. However, the sintering of the protected area (especially near the surface away from the Ni internal electrode) is insufficient. If the protective region is insufficiently sintered, problems such as moisture intrusion from the outside will occur, so normally the protective region is baked until it is sufficiently sintered. At this time, the active region is inevitably oversintered, which may reduce the life of the ceramic electronic component.

In order to solve this problem, a countermeasure is taken to add a glass component as a sintering aid to the protected region (see, for example, Patent Document 1). However, since the dielectric constant of the sintering aid is generally low, the diffusion of the sintering aid into the active region will result in a decrease in the capacity of the ceramic electronic component, or it will become a liquid phase with a low melting point and precipitate on the surface and stain. There are disadvantages such as

On the other hand, it is known that adding NiO to the protected region is effective (see Patent Document 2, for example).

JP-A-2004-356305 JP-A-2003-173925

It is considered that the addition of NiO to the protective region does not cause a decrease in capacity due to the diffusion of the additive element into the active region, unlike the countermeasure of adding a glass component as a sintering aid. However, ceramic electronic components with Ni internal electrodes are fired in a reducing atmosphere in order to prevent Ni from oxidizing. Therefore, the NiO exposed on the surface may be reduced to leave a deposit of metallic Ni on the surface. This precipitated Ni reacts with the plating solution in the electrolytic plating process of the external terminals, and may cause plating extension and poor surface appearance (spots). In addition, when conductive deposits are present on the surface, a leak path for surface discharge may be formed in high-voltage ceramic electronic components and the like.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a ceramic electronic component and a method of manufacturing the same that can suppress the difference in sintering between inside and outside while suppressing the exposure of Ni.

A ceramic electronic component according to the present invention has a substantially rectangular parallelepiped shape in which dielectric layers containing ceramic as a main component and internal electrode layers are alternately laminated, and the plurality of laminated internal electrode layers are alternately laminated. a cover layer having the same main component as that of the dielectric layer; The protection region composed of the side margins provided so as to cover the ends extending to the two side surfaces other than the two end surfaces of the plurality of internal electrode layers laminated in the above is mainly composed of BaTiO ₃ dissolved in Ni solid solution. In addition, in the crystal grains of Ni solid solution BaTiO ₃ in the protection region, the average value of the Ni substitution solid solution amount with respect to BaTiO ₃ is 0.1 atm % or more and 9.0 atm % or less.

In the crystal grains of Ni-solid-solution BaTiO ₃ on the outer surface of the protective region of the ceramic electronic component, the average value of the Ni-substitution solid-solution amount with respect to BaTiO ₃ may be 0.1 atm % or more.

More than half of the BaTiO ₃ crystal grains on the outer surface of the protective region of the ceramic electronic component may be Ni solid-solution BaTiO ₃ having a Ni-substitution solid-solution amount of 0.1 atm % or more.

An average crystal grain size of BaTiO ₃ in the protection region of the ceramic electronic component may be 150 nm or more and 500 nm or less.

In the above ceramic electronic component, the cover layer may have a thickness of 15 μm or more.

In the side margin of the ceramic electronic component, the thickness from the internal electrode layer to the two side surfaces may be 15 μm or more. In the above ceramic electronic component, the dielectric layer in the region where the internal electrode layers exposed on different end faces of the two end faces face each other may contain barium titanate in which Ni is not solid-dissolved as a main component.

In the method for manufacturing a ceramic electronic component according to the present invention, a sheet containing BaTiO ₃ particles as a main component ceramic and a pattern of a metal conductive paste are alternately laminated so that the metal conductive paste is exposed on two opposing end faces. preparing a ceramic laminate including a laminate portion, cover sheets arranged on upper and lower surfaces of the laminate portion in the lamination direction, and side margin regions arranged on side surfaces of the laminate portion; sintering the body, wherein Ni _- solid-solution BaTiO ₃ is the main component ceramic in the peripheral region composed of the cover sheet and the side margin region, and the Ni-solution BaTiO ₃ is The average value of the Ni substitution solid solution amount is 0.1 atomic % or more and 9.0 atomic % or less .

In the method for manufacturing a ceramic electronic component, the first pattern of the metallic conductive paste is placed on the green sheet containing BaTiO ₃ particles as the main component ceramic, and the Ni solid paste is applied to the peripheral area of the metallic conductive paste on the green sheet. The lamination portion and the side margin regions may be formed by arranging a second pattern containing molten BaTiO ₃ as a main component ceramic and laminating a plurality of lamination units thus obtained.

In the method for manufacturing a ceramic electronic component, the side margin regions may be formed by attaching a sheet containing BaTiO ₃ as a main component ceramic to the side surface of the laminated portion. In the method for manufacturing a ceramic electronic component, the BaTiO ₃ particles in the sheet containing the BaTiO 3 particles as a main component ceramic _may be BaTiO ₃ particles in which Ni is not dissolved .

According to the present invention, it is possible to suppress the internal/external difference in sintering while suppressing the exposure of Ni.

1 is a partial cross-sectional perspective view of a laminated ceramic capacitor; FIG. FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1; FIG. 2 is a cross-sectional view taken along line BB of FIG. 1; (a) is an enlarged cross-sectional view of a side margin region, and (b) is an enlarged cross-sectional view of an end margin region. It is a figure which illustrates the flow of the manufacturing method of a laminated ceramic capacitor. It is a figure which illustrates a lamination process. It is a figure which illustrates a lamination process.

Hereinafter, embodiments will be described with reference to the drawings.

(embodiment)
First, an outline of the multilayer ceramic capacitor will be described. FIG. 1 is a partial cross-sectional perspective view of a laminated ceramic capacitor 100 according to an embodiment. FIG. 2 is a cross-sectional view taken along line AA of FIG. 3 is a cross-sectional view taken along line BB of FIG. 1. FIG. As illustrated in FIGS. 1 to 3, the laminated ceramic capacitor 100 includes a rectangular parallelepiped laminated chip 10 and external electrodes 20a and 20b provided on two opposing end surfaces of the laminated chip 10. As shown in FIGS. Of the four surfaces of the laminated chip 10 other than the two end surfaces, two surfaces other than the top surface and the bottom surface in the stacking direction are referred to as side surfaces. The external electrodes 20a and 20b extend on the upper surface, lower surface and two side surfaces of the laminated chip 10 in the lamination direction. However, the external electrodes 20a and 20b are separated from each other.

A laminated chip 10 has a structure in which dielectric layers 11 containing a ceramic material functioning as a dielectric and internal electrode layers 12 containing a base metal material are alternately laminated. The edge of each internal electrode layer 12 is alternately exposed to the end face provided with the external electrode 20a of the laminated chip 10 and the end face provided with the external electrode 20b. Thereby, each internal electrode layer 12 is alternately connected to the external electrode 20a and the external electrode 20b. As a result, the multilayer ceramic capacitor 100 has a configuration in which a plurality of dielectric layers 11 are laminated with internal electrode layers 12 interposed therebetween. In the laminated body of the dielectric layers 11 and the internal electrode layers 12 , the internal electrode layer 12 is arranged as the outermost layer in the lamination direction, and the upper and lower surfaces of the laminated body are covered with the cover layer 13 . The cover layer 13 is mainly composed of a ceramic material. For example, the material of the cover layer 13 is the same as the main component of the dielectric layer 11 and the ceramic material.

The size of the multilayer ceramic capacitor 100 is, for example, length 0.25 mm, width 0.125 mm, and height 0.125 mm, or length 0.4 mm, width 0.2 mm, height 0.2 mm, or length 0.6 mm, 0.3 mm wide and 0.3 mm high; or 1.0 mm long, 0.5 mm wide and 0.5 mm high; or 3.2 mm long, 1.6 mm wide and 0.5 mm high. 1.6 mm in height, or 4.5 mm in length, 3.2 mm in width and 2.5 mm in height, but are not limited to these sizes.

The internal electrode layers 12 are mainly composed of Ni (nickel). The dielectric layer 11 is mainly composed of, for example, a ceramic material having a perovskite structure represented by the general formula _ABO3 . Note that the perovskite structure contains ABO _3-α deviating from the stoichiometric composition. In this embodiment, BaTiO ₃ (barium titanate) is used as the ceramic material.

As illustrated in FIG. 2, the area where the internal electrode layer 12 connected to the external electrode 20a and the internal electrode layer 12 connected to the external electrode 20b face each other is the area that produces the capacitance in the multilayer ceramic capacitor 100. . Therefore, this area is called an active area 14 . That is, the active region 14 is the region where two adjacent internal electrode layers 12 connected to different external electrodes face each other.

A region in which the internal electrode layers 12 connected to the external electrode 20a face each other without interposing the internal electrode layers 12 connected to the external electrode 20b is called an end margin 15 . The end margin 15 is also a region where the internal electrode layers 12 connected to the external electrode 20b face each other without interposing the internal electrode layers 12 connected to the external electrode 20a. That is, the end margin 15 is a region where the internal electrode layers 12 connected to the same external electrode face each other without interposing the internal electrode layers 12 connected to different external electrodes. The end margin 15 is a region that does not produce capacitance.

As exemplified in FIG. 3 , in the laminated chip 10 , regions from two side surfaces of the laminated chip 10 to the internal electrode layers 12 are called side margins 16 . That is, the side margin 16 is a region provided so as to cover the end portions of the plurality of internal electrode layers 12 laminated in the laminated structure extending to the two side surfaces. A region formed by the cover layer 13 and the side margins 16 is called a protection region 50 .

FIG. 4A is an enlarged cross-sectional view of the side margin 16. FIG. The side margin 16 has a structure in which the dielectric layers 11 and the reverse pattern layers 17 are alternately stacked in the stacking direction of the dielectric layers 11 and the internal electrode layers 12 in the active region 14 . Each dielectric layer 11 in the active region 14 and each dielectric layer 11 in the side margins 16 are layers that are continuous with each other. According to this configuration, the step between the active region 14 and the side margin 16 is suppressed.

FIG. 4(b) is an enlarged cross-sectional view of the end margin 15. FIG. In comparison with the side margins 16 , in the end margins 15 , the internal electrode layers 12 of the plurality of laminated internal electrode layers 12 extend to the end faces of the end margins 15 every other one. In addition, the reverse pattern layer 17 is not laminated in the layer where the internal electrode layer 12 extends to the end face of the end margin 15 . Each dielectric layer 11 of the active area 14 and each dielectric layer 11 of the end margin 15 are layers that are continuous with each other. According to this configuration, the step between the active region 14 and the end margin 15 is suppressed.

In this embodiment, as the main component of the protection region 50, BaTiO ₃ in which Ni is dissolved in the crystal lattice by substitution (hereinafter referred to as Ni-dissolved BaTiO ₃ ) is used. As shown in Table 1 below, since the ionic _radius of tetravalent Ti (Ti ⁴⁺ ) and the ionic radius of divalent or trivalent Ni (Ni ²⁺ or Ni ³⁺ ) are close, B Some of the sites (Ti sites) are replaced by Ni. In this way, a state in which a part of the B sites of BaTiO ₃ perovskite is substituted with Ni is a state in which Ni is substituted and solid-solved in the crystal lattice of BaTiO ₃ . The source of Table 1 is "RD Shannon, Acta Crystallogr., A32, 751 (1976)".

Since the Ni substituted and dissolved in the crystal lattice of BaTiO ₃ is stable, it is not separated as a metal even by reduction firing. Therefore, exposure of Ni as a metal is suppressed. On the other hand, sintering of BaTiO ₃ in which Ni is substituted and solid-dissolved is promoted. As a result, the difference between the sintering of the protection region 50 and the sintering of the active region 14 (inside-outside difference) can be suppressed while suppressing the exposure of Ni. As described above, the active region 14 is not oversintered, and the deterioration of the life of the multilayer ceramic capacitor 100 is suppressed. Thereby, the multilayer ceramic capacitor 100 with high capacity and high reliability is realized.

In addition, since the sintering aid does not have to be added to the protective region 50, diffusion of the sintering aid into the active region 14 is suppressed. Alternatively, since the amount of the sintering aid added can be reduced, diffusion of the sintering aid into the active region 14 is suppressed. Thereby, a decrease in dielectric constant of the active region 14 is suppressed.

Note that the main component in the protection region 50 is BaTiO ₃ in Ni solid solution, which means that there may be a part of the protection region 50 where the concentration of BaTiO ₃ in which Ni does not dissolve in solid solution is high. means For example, the side margins 16 may have a higher concentration of BaTiO ₃ in which Ni does not form a solid solution, compared to the cover layer 13 . In this way, when considering the protection region 50 as a whole, the main component should be BaTiO ₃ dissolved in Ni.

From the viewpoint of suppressing a decrease in service life, it is preferable that insufficient sintering on the outer surface of the protection region 50 is suppressed. Therefore, it is preferable to set a lower limit to the amount of Ni in solid solution by substitution in BaTiO ₃ in Ni solid solution on the outer surface of the protection region 50 . Specifically, in each crystal grain of Ni solid solution BaTiO ₃ on the outer surface of the protection region 50 , the average value of the Ni substitution solid solution amount with respect to BaTiO ₃ is preferably 0.1 atm % or more, and preferably 1.0 atm %. % or more, more preferably 2.0 atm % or more. Incidentally, the Ni-substitution solid-solution amount is the amount of Ni when Ti is 100 atm %.

It is to be noted that Ni does not have to dissolve in all the BaTiO ₃ crystal grains on the outer surface of the protection region 50 . For example, on the outer surface of the protection region 50, more than half of the BaTiO ₃ crystal grains are preferably Ni solid solution BaTiO ₃ with a Ni substitution solid solution amount of 0.1 atm% or more, and 70% or more of the BaTiO ₃ crystal grains However, it is more preferable to use BaTiO ₃ with a Ni solid solution amount of 0.1 atm% or more, and 90% or more of the BaTiO ₃ crystal grains are Ni solid solution with a Ni substitution solid solution amount of 0.1 atm% or more. More preferably, it is fused _BaTiO3 .

In each Ni-solid-solution BaTiO ₃ crystal grain of the protection region 50 , if the amount of Ni substitution solid-solution with respect to BaTiO ₃ is too small, there is a possibility that the difference between inside and outside of sintering may not be sufficiently suppressed. Therefore, it is preferable to set a lower limit for the amount of Ni substitution solid solution in Ni solid solution BaTiO ₃ crystal grains. Specifically, in each crystal grain of Ni solid solution BaTiO ₃ in the protection region 50, the average value of the Ni substitution solid solution amount with respect to BaTiO ₃ is preferably 0.1 atm% or more, and 1.0 atm% or more. more preferably 2.0 atm % or more.

On the other hand, in each Ni-solid-solution BaTiO ₃ crystal grain in the protection region 50, if the amount of Ni substitution solid-solution with respect to BaTiO ₃ is too large, NiO will remain, secondary phase will be generated, particle shape will deteriorate, particle size distribution will deteriorate, etc. densification may be delayed due to Therefore, it is preferable to set an upper limit for the amount of Ni substitution solid solution in Ni solid solution BaTiO ₃ crystal grains. Specifically, in each crystal grain of Ni-solid-solution BaTiO ₃ in the protection region 50, the average value of the Ni-substitution solid-solution amount with respect to BaTiO ₃ is preferably 9.0 atm% or less, and 6.0 atm% or less. more preferably 4.0 atm % or less.

Moreover, if the crystal grain size in the protection region 50 is too small or too large, voids may remain inside the protection region 50 after sintering, resulting in a decrease in the density of the protection region 50 . Therefore, it is preferable to set a lower limit and an upper limit for the crystal grain size of BaTiO ₃ in the protection region 50 . Specifically, the average grain size of BaTiO ₃ in the protection region 50 is preferably 150 nm or more and 500 nm or less.

In addition, the present embodiment provides a particularly large effect when the cover layer 13 is thick and the difference (inside/outside difference) between the sintering of the protection region 50 and the sintering of the active region 14 can be large. For example, a particularly large effect is obtained when the cover layer 13 has a thickness of 15 μm or more. Similarly, the present embodiment is particularly effective when the side margins 16 are thick and the difference between the sintering of the protection region 50 and the sintering of the active region 14 (inside-outside difference) can be large. For example, when the thickness of the side margins 16 from the internal electrode layers 12 to the two side surfaces is 15 μm or more, a particularly large effect can be obtained.

Next, a method for manufacturing the laminated ceramic capacitor 100 will be described. FIG. 5 is a diagram illustrating the flow of the manufacturing method of the multilayer ceramic capacitor 100. As shown in FIG.

(Raw material powder preparation process)
As illustrated in FIG. 5, first, a dielectric material for forming the dielectric layer 11 is prepared. The A-site and B-site elements contained in the dielectric layer 11 are usually contained in the dielectric layer 11 in the form of sintered particles of _ABO3 . For example, BaTiO ₃ is a tetragonal compound with a perovskite structure and exhibits a high dielectric constant. This BaTiO ₃ can generally be obtained by reacting a titanium raw material such as titanium dioxide with a barium raw material such as barium carbonate to synthesize barium titanate. Various methods are conventionally known for synthesizing the main component ceramic of the dielectric layer 11, such as a solid phase method, a sol-gel method, and a hydrothermal method. Any of these can be employed in the present embodiment.

A predetermined additive compound is added to the obtained ceramic powder according to the purpose. Additive compounds include Mg (magnesium), Mn (manganese), V (vanadium), Cr (chromium), rare earth elements (Y (yttrium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb ( terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium) and Yb (ytterbium)) oxides, as well as Co (cobalt), Ni, Li (lithium), B (boron) , Na (sodium), K (potassium) and Si (silicon) oxides or glasses.

Next, a reverse pattern material for forming the end margins 15 and the side margins 16 is prepared. Ni solid solution BaTiO ₃ powder is prepared as a reverse pattern material. For example, Ni-solid-solution _BaTiO3 powder is produced by a solid-phase synthesis method in which _BaCO3 powder, _TiO2 powder, and NiO powder are wet-mixed, dried, and fired at about 850°C to 1000°C for 2 hours. be able to. Since the ionic radius of tetravalent Ti (Ti ⁴⁺ ) and the ionic radius of divalent or trivalent Ni (Ni ²⁺ or Ni ³⁺ ) are close, some of the Ti sites in BaTiO ₃ perovskite are replaced by Ni. "Ni solid solution BaTiO ₃ " is obtained. Since the powder thus produced after synthesis is agglomerated, a dry or wet pulverization treatment is performed to pulverize the secondary agglomeration so as to obtain a desired particle size distribution. The Ni solid solution BaTiO ₃ prepared in this way may have a structure in which the Ni concentration is not uniform up to the center of the powder at this point, and Ni is present at a high concentration near the particle surface. It is sufficient that Ni is uniformly diffused to the part and combined with adjacent grains to form grains having a uniform internal Ni concentration while accompanied by grain growth.

Predetermined additive compounds are added to the obtained Ni solid solution BaTiO ₃ powder according to the purpose. Additive compounds include oxides of Mg, Mn, V, Cr, rare earth elements (Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb), Co, Ni, Li, B, Examples include Na, K and Si oxides or glasses.

Next, a cover material for forming the cover layer 13 is prepared. Ni solid solution BaTiO ₃ powder is prepared as a cover material. The Ni solid solution BaTiO ₃ powder can be produced by the same procedure as the reverse pattern material.

Predetermined additive compounds are added to the obtained Ni solid solution BaTiO ₃ powder according to the purpose. Additive compounds include oxides of Mg, Mn, V, Cr, rare earth elements (Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb), Co, Ni, Li, B, Examples include Na, K and Si oxides or glasses.

(Lamination process)
Next, a laminated portion in which a sheet containing BaTiO ₃ particles as a main component ceramic and a pattern of a metallic conductive paste are alternately laminated so that the metallic conductive paste is exposed on the two end faces facing each other, and a lamination of the laminated portion A ceramic laminate is provided that includes cover sheets located on the top and bottom surfaces of the laminate and side margin regions located on the sides of the laminate. In the ceramic laminate, Ni solid-solution BaTiO ₃ is used as the main component ceramic in the peripheral region composed of the cover sheet and the side margin regions.

Specifically, first, a binder such as polyvinyl butyral (PVB) resin, an organic solvent such as ethanol or toluene, and a plasticizer are added to the dielectric material obtained in the raw material powder preparation step, and wet-mixed. Using the obtained slurry, a strip-shaped dielectric green sheet 51 having a thickness of, for example, 0.8 μm or less is coated on the substrate by, for example, a die coater method or a doctor blade method, and dried.

Next, as exemplified in FIG. 6, a metal conductive paste for forming internal electrodes containing an organic binder is printed on the surface of the dielectric green sheet 51 by screen printing, gravure printing, or the like to form internal electrode layers. A first pattern 52 is placed. Ceramic particles are added to the metal conductive paste as a common material. Although the main component of the ceramic particles is not particularly limited, it is preferably the same as the main component ceramic of the dielectric layer 11 .

Next, a binder such as ethyl cellulose and an organic solvent such as terpineol are added to the reverse pattern material obtained in the raw material powder preparation step, and kneaded in a roll mill to obtain a reverse pattern paste for the reverse pattern layer. As exemplified in FIG. 6, on the dielectric green sheet 51, the second pattern 53 is arranged by printing the reverse pattern paste in the peripheral area where the first pattern 52 is not printed, and the second pattern 53 is arranged. fill in the gaps.

After that, the internal electrode layers 12 are alternately exposed on both end faces in the length direction of the dielectric layers 11 so that the internal electrode layers 12 and the dielectric layers 11 are alternately exposed to form a pair of different polarities. A dielectric green sheet 51, a first pattern 52 and a second pattern 53 are laminated so as to be alternately led out to the external electrodes 20a and 20b. For example, it is assumed that the dielectric green sheet 51 has 100 to 500 layers.

Next, a binder such as polyvinyl butyral (PVB) resin, an organic solvent such as ethanol or toluene, and a plasticizer are added to the cover material obtained in the raw material powder preparation step, and wet-mixed. Using the obtained slurry, a strip-shaped cover sheet 54 having a thickness of, for example, 10 μm or less is coated on the substrate by, for example, a die coater method or a doctor blade method, and dried. A predetermined number (for example, 2 to 10 layers) of cover sheets 54 are laminated on the top and bottom of the laminated dielectric green sheet 51 and thermally pressed, cut into a predetermined chip size (for example, 1.0 mm×0.5 mm), and then Next, a metal conductive paste, which will be the external electrodes 20a and 20b, is applied to both sides of the cut laminate by a dipping method or the like and dried. A ceramic laminate is thus obtained. Alternatively, a predetermined number of cover sheets 54 may be stacked and pressure-bonded before being attached to the upper and lower sides of the stacked dielectric green sheets 51 .

In the method of FIG. 6, the portion corresponding to the first pattern 52 of the dielectric green sheet 51 and the region where the first pattern 52 is laminated are formed by the sheet containing BaTiO ₃ particles as the main component ceramic and the metal conductive paste. It corresponds to a layered portion in which patterns are alternately layered. A region where the portion of the dielectric green sheet 51 protruding outside the first pattern 52 and the second pattern 53 are laminated corresponds to a side margin region arranged on the side surface of the laminated portion.

The side margin regions may be attached or applied to the side surfaces of the laminated portion. Specifically, as illustrated in FIG. 7, dielectric green sheets 51 and first patterns 52 having the same width as the dielectric green sheets 51 are alternately laminated to obtain a laminated portion. Next, a side margin region may be formed with a second pattern 53 obtained by attaching a sheet formed of a reverse pattern paste or applying a reverse pattern paste to the side surface of the laminated portion.

(Baking process)
After removing the binder from the ceramic laminate thus obtained in an N ₂ atmosphere, a Ni paste that serves as a base for the external electrodes 20a and 20b was applied by a dipping method, and the partial pressure of oxygen was 10 ⁻⁵ to 10 ⁻⁸ atm. 10 minutes to 2 hours at 1100 to 1300° C. in a reducing atmosphere. Thus, the laminated ceramic capacitor 100 is obtained.

(Reoxidation treatment step)
After that, reoxidation treatment may be performed at 600° C. to 1000° C. in an N ₂ gas atmosphere.

(Plating process)
After that, metal coating such as Cu, Ni, and Sn may be applied to the external electrodes 20a and 20b by plating.

According to the present embodiment, the Ni dissolved in the crystal lattice of BaTiO ₃ by substitution is stable and does not separate as a metal even by reduction firing. Therefore, exposure of Ni as a metal is suppressed. On the other hand, sintering of BaTiO ₃ in which Ni is substituted and solid-dissolved is promoted. As a result, the difference between the sintering of the protection region 50 and the sintering of the active region 14 (inside-outside difference) can be suppressed while suppressing the exposure of Ni. As described above, the active region 14 is not oversintered, and the deterioration of the life of the multilayer ceramic capacitor 100 is suppressed. Thereby, the multilayer ceramic capacitor 100 with high capacity and high reliability is realized.

In addition, since the sintering aid does not have to be added to the protective region 50, diffusion of the sintering aid into the active region 14 is suppressed. Alternatively, since the amount of the sintering aid added can be reduced, diffusion of the sintering aid into the active region 14 is suppressed. Thereby, a decrease in dielectric constant of the active region 14 is suppressed.

The reason why the main component in the entire peripheral region composed of the cover sheet and the side margin regions is BaTiO ₃ in Ni solid solution is that the concentration of BaTiO ₃ in which Ni does not dissolve in solid solution is high in a part of the peripheral region. It means that there can be a place where it is. For example, in the side margin region, the concentration of BaTiO ₃ in which Ni is not solid-dissolved may be higher than that in the cover sheet. In this way, when the surrounding area is considered as a whole, the main component should be _BaTiO3 in solid solution with Ni.

Instead of using BaTiO ₃ dissolved in Ni, NiO particles and BaTiO ₃ particles may be mixed, and Ni may be dissolved in BaTiO ₃ in the firing process. However, in this case, Ni is solid-dissolved only in part of the BaTiO ₃ particles, and densification proceeds only in the vicinity of the NiO particles, which may cause "uneven burning". On the other hand, in the present embodiment, BaTiO ₃ in solid solution with Ni is used, so that uneven burning can be suppressed.

In each Ni solid-solution BaTiO ₃ particle in the peripheral region composed of the cover sheet and the side margin region, if the amount of Ni substitution solid solution with respect to BaTiO ₃ is too small, there is a possibility that the difference between inside and outside of sintering may not be sufficiently suppressed. . Therefore, it is preferable to set a lower limit for the amount of Ni substitution solid solution in each Ni solid solution BaTiO ₃ particle. Specifically, in each Ni solid-solution BaTiO ₃ particle in the surrounding region, the average value of the Ni-substitution solid-solution amount with respect to BaTiO ₃ is preferably 0.1 atm% or more, and more preferably 1.0 atm% or more. More preferably, it is 2.0 atm % or more. Incidentally, the Ni-substitution solid-solution amount is the amount of Ni when Ti is 100 atm %.

On the other hand, if a large amount of NiO is mixed in the process of producing BaTiO ₃ in solid solution with Ni, BaNiO ₃ may be synthesized. Otherwise, problems such as NiO remaining or the formation of a secondary phase may occur. Excessive addition of Ni is not preferable because the surface shape of Ni-dissolved BaTiO ₃ particles is angular and the particle size distribution is remarkably deteriorated, causing problems in forming a dielectric green sheet. This may be due to the fact that the crystal system of BaTiO ₃ changes from Tetragonal to Hexagonal when a tetravalent Ni solid solution is formed (detailed mechanism is unknown). Therefore, it is preferable to set an upper limit for the amount of Ni in solid solution. Specifically, the average value of the Ni substitution solid solution amount in each Ni solid solution _BaTiO3 particle is preferably 9.0 atm% or less, more preferably 6.0 atm% or less, relative to Ti. 0 atm % or less is more preferable.

In addition, in each of the above-described embodiments, a laminated ceramic capacitor has been described as an example of a ceramic electronic component, but the present invention is not limited to this. For example, other electronic components such as varistors and thermistors may be used.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations can be made within the scope of the gist of the present invention described in the scope of claims. Change is possible.

10 laminated chip 11 dielectric layer 12 internal electrode layer 13 cover layer 14 active area 15 end margin 16 side margin 17 reverse pattern layer 20a, 20b external electrode 50 protection area 51 dielectric green sheet 52 first pattern 53 second pattern 100 lamination ceramic capacitor

Claims (11)

Dielectric layers containing ceramic as a main component and internal electrode layers are alternately laminated to have a substantially rectangular parallelepiped shape, and the multiple internal electrode layers are alternately exposed on two opposite end surfaces. With formed laminated structure,
A cover layer provided on at least one of the upper surface and the lower surface in the lamination direction of the laminated structure and having the same main component as that of the dielectric layer, The protective region composed of a side margin provided to cover the end extending to the side is mainly composed of Ni solid solution BaTiO ₃ ,
A ceramic electronic component according to claim 1 , wherein, in the crystal grains of BaTiO ₃ in Ni solid solution in the protection region , an average value of Ni substitution solid solution amount with respect to BaTiO ₃ is 0.1 atomic % or more and 9.0 atomic % or less. 2. The ceramic electronic component according to claim 1, wherein, in the crystal grains of Ni solid solution BaTiO ₃ on the outer surface of said protective region, the average value of the Ni substitution solid solution amount with respect to BaTiO ₃ is 0.1 atm % or more. . 3. The ceramic according to claim 1, wherein more than half of the _BaTiO3 crystal grains on the outer surface of the protective region are Ni solid solution _BaTiO3 having a Ni substitution solid solution amount of 0.1 atm % or more. electronic components. 4. The ceramic electronic component according to claim 1, wherein an average grain size of BaTiO ₃ in said protective region is 150 nm or more and 500 nm or less. 5. The ceramic electronic component according to claim 1 , wherein said cover layer has a thickness of 15 μm or more. 6. The ceramic electronic component according to claim 1, wherein the side margin has a thickness of 15 μm or more from the internal electrode layer to the two side surfaces. 6. The dielectric layer in the region where the internal electrode layers exposed on different end faces of the two end faces face each other is mainly composed of barium titanate in which Ni is not solid-dissolved. The ceramic electronic component according to any one of 1. A laminated portion in which a sheet containing BaTiO ₃ particles as a main component ceramic and a pattern of a metallic conductive paste are alternately laminated so that the metallic conductive paste is exposed on two opposing end faces, and an upper surface of the laminated portion in the lamination direction. and a cover sheet disposed on the lower surface, and side margin regions disposed on the side surfaces of the laminate portion;
and firing the ceramic laminate,
In the peripheral region composed of the cover sheet and the side margin region, Ni solid solution BaTiO ₃ is the main component ceramic, and in the Ni solid solution BaTiO ₃ , the average value of the Ni substitution solid solution amount with respect to BaTiO ₃ is A method for producing a ceramic electronic component, wherein the content is 0.1 atm % or more and 9.0 atm % or less . A first pattern of a metal conductive paste is placed on a green sheet containing BaTiO ₃ particles as a main component ceramic, and a Ni-dissolved BaTiO ₃ is used as a main component ceramic in a peripheral area of the metal conductive paste on the green sheet. 9. The method of manufacturing a ceramic electronic component according to claim 8, wherein the laminated portion and the side margin regions are formed by arranging the second pattern and laminating a plurality of lamination units thus obtained. 10. The method of manufacturing a ceramic electronic component according to claim 9, wherein the side margin region is formed by attaching a sheet containing _BaTiO3 as a main component ceramic to the side surface of the laminated portion. The BaTiO ₃ The BaTiO in the sheet with particles as the main component ceramic ₃ The particles are BaTiO ₃ 11. The method for producing a ceramic electronic component according to any one of claims 8 to 10, characterized in that it is particles.

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