Ceramic electronic component and method for manufacturing same

Abstract

The ceramic electronic component includes: a laminated sheet having a substantially rectangular parallelepiped shape, the laminated sheet including a laminated body and a pair of side edges covering two opposing side surfaces of the laminated body, the laminated body including a plurality of dielectric layers and a plurality of internal electrode layers having Ni as a main component and containing a low-melting-point metal on top and bottom of a laminated structure in which the plurality of dielectric layers and the plurality of internal electrode layers are alternately laminated; a pair of coating layers having a ceramic as a main component and having a higher Mg concentration than the dielectric layer; and a pair of external electrodes provided on a first end surface and a second end surface which are substantially rectangular parallelepiped-shaped and face each other, each external electrode having a structure in which a plating layer is provided on a base layer, the plurality of internal electrode layers being alternately exposed on the first end surface and the second end surface, at least the outermost internal electrode layer among the plurality of internal electrode layers has an oxide containing Ni and Mg at both ends in the width direction, and at the end edges, both ends in the width direction of at least some internal electrode layers among the plurality of internal electrode layers are adjacent to the voids.

Description

Technical Field

[0001] The present invention relates to a ceramic electronic component and a method for manufacturing the same. Background Art

[0002] In recent years, in fields such as electric vehicles, there has been a demand for not only miniaturization and higher functionality of ceramic electronic components such as multilayer ceramic capacitors, but also improvements in high-temperature load life and moisture-resistant reliability.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-117051

[0006] Patent Document 2: Japanese Patent Application Publication No. 2021-034648

[0007] Patent Document 3: Japanese Patent Application Laid-Open No. 2009-016796

[0008] Patent Document 4: Japanese Patent Application No. 2014-175034 Summary of the Invention

[0009] Technical problem to be solved by the invention

[0010] To improve high-temperature load life, a multilayer ceramic capacitor has been proposed in which tin (Sn) is added to internal electrode layers primarily composed of nickel (Ni) (Patent Document 1). However, when a low-melting-point metal such as Sn is added to the internal electrode layers, the difference in shrinkage behavior between the dielectric layer and the internal electrode layer during firing becomes even greater. Consequently, gaps form between the widthwise ends of the internal electrode layers and the side edges protecting the widthwise ends of the internal electrode layers, resulting in reduced moisture resistance (Patent Document 2).

[0011] In response to this, it is conceivable to add magnesium (Mg) to the side edges to oxidize and expand the widthwise ends of the internal electrode layers, thereby suppressing voids (Patent Document 3).

[0012] In a multilayer ceramic capacitor having internal electrode layers primarily composed of Ni and external electrodes primarily composed of Cu, during the sintering process of the external electrodes, Cu, the primary metal component of the external electrodes, diffuses toward the internal electrode layers primarily composed of Ni, causing the internal electrode layers to expand. This expansion of the internal electrode layers can cause cracks to form at the corners of the multilayer ceramic capacitor, reducing moisture resistance reliability (Patent Document 4). Adding a low-melting-point metal such as Sn to the internal electrode layers primarily composed of Ni increases the diffusion of Cu, the primary component of the external electrodes. Consequently, when Mg is added to the side edges to suppress voids, cracks are more likely to form at the corners of the laminate.

[0013] The present invention has been made in view of the above-mentioned technical problems, and an object of the present invention is to provide a ceramic electronic component and a method for manufacturing the same that can improve high-temperature load life and moisture-resistant reliability.

[0014] Means for solving technical problems

[0015] The ceramic electronic component of the present invention comprises: a laminate having a substantially rectangular parallelepiped shape, comprising a laminate and a pair of side edges covering two opposing side surfaces of the laminate, wherein the laminate comprises a pair of cover layers composed mainly of ceramic provided above and below a laminate structure in which a plurality of dielectric layers composed mainly of ceramic and a plurality of internal electrode layers composed mainly of Ni are alternately laminated; and a pair of external electrodes provided on opposing first and second end surfaces of the substantially rectangular parallelepiped shape, wherein the plated layer is provided on a base layer, and the plurality of internal electrode layers are alternately exposed on the base layer. The first end face and the second end face, the multiple internal electrode layers each contain a metal component with a melting point of 700°C or less, the Mg concentration of the pair of covering layers is higher than the Mg concentration of the multiple dielectric layers, at least the outermost internal electrode layer among the multiple internal electrode layers has an oxide containing Ni and Mg at both ends in the width direction, and in a region where internal electrode layers connected to the same external electrode are opposite to each other without interposing internal electrode layers connected to different external electrodes, both ends in the width direction of at least some of the multiple internal electrode layers are adjacent to the gap.

[0016] In the above ceramic electronic component, the base layer may be mainly composed of Cu.

[0017] In the ceramic electronic component, the cover layer may have a Mg concentration of 1.5 at % or more, and the dielectric layer may have a Mg concentration of 0.5 at % or less.

[0018] In the above ceramic electronic component, the metal component may include any one of Ga, In, Sn, Bi, Pb, and Zn.

[0019] In the above ceramic electronic component, the Mg concentration of the side edge may be lower than the Mg concentration of the cover layer.

[0020] In the ceramic electronic component, the cover layer may have a Mg concentration of 1.5 at % or more, and the side edge may have a Mg concentration of 0.5 at % or less.

[0021] In the ceramic electronic component, a predetermined number of dielectric layers from the outermost layer among the plurality of dielectric layers may have a higher Mg concentration than the other dielectric layers.

[0022] In the ceramic electronic component, the Mg concentration of the predetermined number of dielectric layers from the outermost layer may be 1.5 at % or higher.

[0023] In the ceramic electronic component, among the plurality of internal electrode layers, the internal electrode layers that are in contact with a predetermined number of the dielectric layers from the outermost layer may have oxides containing Ni and Mg at both ends in the width direction.

[0024] In the ceramic electronic component, the connection portion of each of the plurality of internal electrode layers to the external electrode may be narrower than the width of other regions, and the Mg concentration of the side edge may be higher than the Mg concentration of the dielectric layer.

[0025] In the ceramic electronic component, the Mg concentration at the side edge may be 1.5 at % or higher.

[0026] In the ceramic electronic component, each of the plurality of internal electrode layers may include an oxide containing Ni and Mg at the center in the longitudinal direction and at both ends in the width direction.

[0027] In the above-mentioned ceramic electronic component, the multiple internal electrode layers may include: a first number of outer internal electrode layers starting from the outermost layer; and an inner internal electrode layer located inner than the outer internal electrode layer in the stacking direction, the width of the connection portion of the outer internal electrode layer connected to the external electrode is narrower than the width of other regions, the width of the connection portion of the inner internal electrode layer connected to the external electrode is approximately equal to the width of other regions, and the Mg concentration of the side edge is higher than the Mg concentration of the dielectric layer.

[0028] In the ceramic electronic component, the Mg concentration at the side edge may be 1.5 at % or higher.

[0029] In the ceramic electronic component, each of the outer internal electrode layer and the inner internal electrode layer may include an oxide containing Ni and Mg at the center in the longitudinal direction and at both ends in the width direction.

[0030] The method for manufacturing a ceramic electronic component of the present invention is characterized by comprising: a step of obtaining a first laminate, the first laminate being obtained by laminating a plurality of lamination units each having an internal electrode pattern formed on a dielectric green sheet, wherein the internal electrode pattern comprises Ni as a main component and a metal component having a melting point of 700° C. or less is added thereto; a step of obtaining a second laminate, the second laminate being obtained by laminating cover sheets above and below the first laminate in a lamination direction of the lamination units, the cover sheets having a higher Mg concentration than that of the dielectric green sheet; a step of obtaining a third laminate, the third laminate being obtained by attaching side edge sheets to the second laminate, the side edges covering first and second side surfaces where the internal electrode pattern is exposed, respectively; and a step of forming a base layer, the base layer comprising a metal as a main component being formed on first and second opposing end surfaces of the third laminate during or after firing the third laminate.

[0031] Effects of the Invention

[0032] According to the present invention, a ceramic electronic component capable of improving high-temperature load life and moisture-resistant reliability and a method for manufacturing the same can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 (A) is a partial cross-sectional perspective view of the multilayer ceramic capacitor according to the first embodiment. Figure 1 (B) is a plan view of the multilayer ceramic capacitor according to the first embodiment.

[0034] Figure 2 yes Figure 1 (B) AA line cross-sectional view.

[0035] Figure 3 (A) is Figure 1 (B) BB line cross-sectional view, Figure 3 (B) is Figure 1 (B) CC line cross-sectional view.

[0036] Figure 4 This is an enlarged cross-sectional view near the external electrode.

[0037] Figure 5 (A) and Figure 5 (B) is a cross-sectional view showing an example of a conventional multilayer ceramic capacitor.

[0038] Figure 6 This is a diagram illustrating a crack.

[0039] Figure 7This is a flowchart illustrating a method for manufacturing a multilayer ceramic capacitor according to the first embodiment.

[0040] Figure 8 A diagram illustrating an outline of a method for manufacturing a multilayer ceramic capacitor.

[0041] Figure 9 (A) is a partial cross-sectional perspective view of a multilayer ceramic capacitor according to a second embodiment. Figure 9 (B) is a cross-sectional view of the multilayer ceramic capacitor according to the second embodiment.

[0042] Figure 10 A diagram schematically illustrating a method for manufacturing a multilayer ceramic capacitor according to a second embodiment.

[0043] Figure 11 (A) and Figure 11 (B) is a partial cross-sectional perspective view of the multilayer ceramic capacitor according to the third embodiment.

[0044] Figure 12 It is a cross-sectional view of a multilayer ceramic capacitor according to a third embodiment.

[0045] Figure 13 (A) and Figure 13 (B) is a cross-sectional view of the multilayer ceramic capacitor according to the third embodiment.

[0046] Figure 14 A diagram schematically illustrating a method for manufacturing a multilayer ceramic capacitor according to a third embodiment.

[0047] Figure 15 (A) and Figure 15 (B) is a partial cross-sectional perspective view of the multilayer ceramic capacitor according to the fourth embodiment.

[0048] Figure 16 (A) and Figure 16 (B) is a cross-sectional view of the multilayer ceramic capacitor according to the fourth embodiment.

[0049] Figure 17 A diagram schematically illustrating a method for manufacturing a multilayer ceramic capacitor according to a fourth embodiment. DETAILED DESCRIPTION

[0050] Hereinafter, embodiments will be described with reference to the accompanying drawings.

[0051] (First embodiment)

[0052] Figure 1 (A) is a partial cross-sectional perspective view of the multilayer ceramic capacitor 100 according to the first embodiment. Figure 1 (B) is a plan view of the multilayer ceramic capacitor 100 . Figure 2 yes Figure 1 (B) AA line cross-sectional view. Figure 3 (A) is Figure 1 (B) BB line cross-sectional view, Figure 3 (B) is Figure 1 The CC line cross-sectional view of (B) shows a cross section in a region corresponding to an end edge 15 described later.

[0053] like Figure 1 As shown in (A), a multilayer ceramic capacitor 100 includes a laminate 10 having a generally rectangular parallelepiped shape and external electrodes 20a and 20b provided on two opposing end surfaces of the laminate 10. Of the four surfaces of the laminate 10 other than the two end surfaces, two surfaces other than the top and bottom surfaces in the stacking direction are referred to as side surfaces. External electrodes 20a and 20b extend along the top, bottom, and two side surfaces of the laminate 10 in the stacking direction. However, external electrodes 20a and 20b are spaced apart from each other.

[0054] In addition, Figure 1 (A)~ Figure 3 In (B), the L direction is the length direction of the laminate 10, the direction in which the two end surfaces of the laminate 10 face each other, and the direction in which the external electrodes 20a and 20b face each other. The W direction is the width direction of the internal electrode layer, and the direction in which the two side surfaces of the laminate 10 face each other. The T direction is the stacking direction, and the direction in which the top and bottom surfaces of the laminate 10 face each other. The L, W, and T directions are orthogonal to each other.

[0055] The laminated sheet 10 includes: a laminated body 17 having a substantially rectangular parallelepiped shape; and side edges 16 ( Figure 3 (A) and Figure 3 (B) The laminate 17 includes a pair of cover layers 13 , and a structure in which dielectric layers 11 made of a ceramic material functioning as a dielectric and internal electrode layers 12 containing Ni as a main component are alternately stacked between the pair of cover layers 13 .

[0056] The end edges of each internal electrode layer 12, along their extending direction, alternately expose the first end surface of the laminate 10, where the external electrode 20a is provided, and the second end surface of the laminate 10, where the external electrode 20b is provided. Internal electrode layers 12 connected to external electrode 20a are not connected to external electrode 20b. Internal electrode layers 12 connected to external electrode 20b are not connected to external electrode 20a. Therefore, each internal electrode layer 12 alternately maintains electrical continuity with external electrode 20a and external electrode 20b.

[0057] like Figure 2As shown in the example, the region 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 region where capacitance is generated in the multilayer ceramic capacitor 100. Therefore, this region where capacitance is generated is referred to as the capacitor portion 14. In other words, the capacitor portion 14 is the region where adjacent internal electrode layers 12 connected to different external electrodes face each other.

[0058] The region where internal electrode layers 12 connected to external electrode 20a face each other without interposing internal electrode layers 12 connected to external electrode 20b is referred to as end edge 15. Furthermore, the region where internal electrode layers 12 connected to external electrode 20b face each other without interposing internal electrode layers 12 connected to external electrode 20a is also referred to as end edge 15. In other words, end edge 15 is a region where internal electrode layers 12 connected to the same external electrode face each other without interposing internal electrode layers 12 connected to different external electrodes. End edge 15 is a region where no capacitance is generated.

[0059] like Figure 3 (A) and Figure 3 As shown in (B) of FIG, in the laminate of dielectric layers 11 and internal electrode layers 12, internal electrode layer 12 is arranged at the uppermost layer in the stacking direction, and internal electrode layer 12 is also arranged at the lowermost layer in the stacking direction. The upper and lower surfaces of the laminate are covered with cover layers 13. In other words, a pair of cover layers 13 face each other in the stacking direction with capacitor portion 14 and end edge 15 interposed therebetween. Cover layers 13 are primarily composed of ceramic material.

[0060] Furthermore, both side faces in the W direction of the laminate 17, which includes the laminate of the dielectric layer 11 and the internal electrode layer 12, and the pair of cover layers 13, are covered by side edges 16. Specifically, side edges 16 cover the W direction ends of the internal electrode layer 12, the dielectric layer 11, and the cover layers 13. Side edges 16 extend from the first end face to the second end face of the laminate 10, and from the top surface to the bottom surface of the laminate 10. Side edges 16 are primarily composed of a ceramic material. For example, the primary component material of side edges 16 is the same as the primary component material of the dielectric layer 11. Side edges 16 are also regions that do not generate capacitance.

[0061] The dimensions of the multilayer ceramic capacitor 100 are, for example, 0.25 mm in length, 0.125 mm in width, and 0.125 mm in height, or 0.4 mm in length, 0.2 mm in width, and 0.2 mm in height, or 0.6 mm in length, 0.3 mm in width, and 0.3 mm in height, or 0.6 mm in length, 0.3 mm in width, and 0.110 mm in height, or 1.0 mm in length, 0.5 mm in width, and 0.5 mm in height, or 1.0 mm in length, 0.5 mm in width, and 0.1 mm in height, or 3.2 mm in length, 1.6 mm in width, and 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 dimensions.

[0062] The internal electrode layer 12 is mainly composed of nickel (Ni). In this embodiment, in order to improve the electrical barrier at the interface between the dielectric layer 11 and the internal electrode layer 12 and to improve the high-temperature load life, a metal component with a melting point lower than 700°C (hereinafter referred to as a low-melting-point metal) is added to the internal electrode layer 12. The low-melting-point metal is not particularly limited as long as its melting point is lower than 700°C, and examples include gallium (Ga), indium (In), tin (Sn), bismuth (Bi), lead (Pb), zinc (Zn), etc. The low-melting-point metal can form an alloy with Ni, which is the main component of the internal electrode layer 12, or can be configured as a single metal. For example, the low-melting-point metal can be uniformly dispersed in the internal electrode layer 12, or can be segregated at the interface between the internal electrode layer 12 and the dielectric layer 11.

[0063] The concentration of the low-melting-point metal in the internal electrode layer 12 is, for example, 1 at%. Here, the concentration of the low-melting-point metal refers to the amount (at%) of the low-melting-point metal in the entire internal electrode layer 12 sandwiched between two adjacent dielectric layers 11, when Ni in the internal electrode layer 12 is assumed to be 100 at%. Furthermore, when multiple low-melting-point metals are included, the concentration of the low-melting-point metal refers to the total amount of the multiple low-melting-point metals.

[0064] From the perspective of improving the electrical barrier at the interface between the dielectric layer 11 and the internal electrode layer 12 and thereby increasing the high-temperature load life, the concentration of the low-melting-point metal in the internal electrode layer 12 is preferably 0.3 at% or greater, more preferably 0.5 at% or greater. On the other hand, from the perspective of suppressing excessive shrinkage of the internal electrode layer 12, the concentration of the low-melting-point metal in the internal electrode layer 12 is preferably 5 at% or less, more preferably 3 at% or less.

[0065] The thickness of each internal electrode layer 12 is, for example, not less than 0.1 μm and not more than 2 μm. The thickness of each internal electrode layer 12 can be measured as follows: Figure 2After the cross section is exposed, an image is taken using a microscope such as a scanning transmission electron microscope, and the average thickness of 10 locations is determined.

[0066] The dielectric layer 11 is mainly composed of a ceramic material having a perovskite structure represented by the general formula ABO3. In addition, the perovskite structure contains ABO3 deviating from the stoichiometric composition. 3-α For example, as the ceramic material, a material selected from barium titanate (BaTiO3), calcium zirconate (CaZrO3), calcium titanate (CaTiO3), strontium titanate (SrTiO3), magnesium titanate (MgTiO3), BaTiO3, which forms a perovskite structure, can be used. 1-x-y Ca x Sr y Ti 1-z Zr z At least one of O3 (0≤x≤1, 0≤y≤1, 0≤z≤1), etc. 1-x- y Ca x Sr y Ti 1-z Zr z O3 is barium strontium titanate, barium calcium titanate, barium zirconate, barium titanate zirconate, calcium titanate zirconate and barium calcium titanate.

[0067] Additives may be added to the dielectric layer 11. Examples of additives that may be added to the dielectric layer 11 include oxides of magnesium (Mg), manganese (Mn), molybdenum (Mo), vanadium (V), chromium (Cr), rare earth elements (yttrium (Y), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), and ytterbium (Yb)), oxides containing cobalt (Co), nickel (Ni), lithium (Li), boron (B), sodium (Na), potassium (K), or silicon (Si), and glasses containing Co, Ni, Li, B, Na, K, or Si.

[0068] The thickness of each dielectric layer 11 is, for example, not less than 0.3 μm and not more than 3 μm. The thickness of each dielectric layer 11 can be measured as follows: Figure 2 After the cross section is exposed, an image is taken using a microscope such as a scanning transmission electron microscope, and the average thickness of 10 locations is determined.

[0069] The side edge 16 is mainly composed of a ceramic material having a perovskite structure represented by the general formula ABO3. In addition, the perovskite structure contains ABO3 deviating from the stoichiometric composition. 3-α For example, as the ceramic material, BaTiO3, CaZrO3, CaTiO3, SrTiO3, MgTiO3, Ba that forms a perovskite structure,1-x-y Ca x Sr y Ti 1-z Zr z At least one of O3 (0≤x≤1, 0≤y≤1, 0≤z≤1), etc. 1-x-y Ca x Sr y Ti 1-z Zr z O3 is barium strontium titanate, barium calcium titanate, barium zirconate, barium titanate zirconate, calcium titanate zirconate and barium calcium titanate.

[0070] Additives may be added to the side edges 16. Examples of additives that may be added to the side edges 16 include oxides of Mg, Mn, Mo, V, Cr, rare earth elements (Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb), oxides containing Co, Ni, Li, B, Na, K, or Si, or glass containing Co, Ni, Li, B, Na, K, or Si.

[0071] The covering layer 13 is mainly composed of a ceramic material having a perovskite structure represented by the general formula ABO3. In addition, the perovskite structure contains ABO3 deviating from the stoichiometric composition. 3-α For example, as the ceramic material, BaTiO3, CaZrO3, CaTiO3, SrTiO3, MgTiO3, Ba that forms a perovskite structure, 1-x-y Ca x Sr y Ti 1-z Zr z At least one of O3 (0≤x≤1, 0≤y≤1, 0≤z≤1), etc. 1-x-y Ca x Sr y Ti 1-z Zr z O3 is barium strontium titanate, barium calcium titanate, barium zirconate, barium titanate zirconate, calcium titanate zirconate and barium calcium titanate.

[0072] Additives may be added to the cover layer 13. Examples of additives added to the side edges 16 include oxides of Mg, Mn, Mo, V, Cr, rare earth elements (Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb), oxides containing Co, Ni, Li, B, Na, K, or Si, and glasses containing Co, Ni, Li, B, Na, K, or Si.

[0073] Figure 4 This is an enlarged cross-sectional view near the external electrode 20a. Figure 4 In the example, hatching is omitted. Figure 4 As illustrated, the external electrode 20a has a structure in which a plating layer 22 is provided on a base layer 21 as a contact layer in contact with the first end face of the laminate 10. The base layer 21 has Ni, Cu, etc. as main components. The base layer 21 may also contain ceramic particles such as BaTiO3 as a common material, or may contain a glass component. The plating layer 22 has metals such as Cu, Ni, aluminum (Al), zinc (Zn), Sn, or alloys of two or more thereof as main components. The plating layer 22 may be a plating layer of a single metal component, or may be a plurality of plating layers of metal components different from each other. For example, the plating layer 22 has a structure in which a first plating layer 23, a second plating layer 24, and a third plating layer 25 are formed in sequence from the base layer 21 side. The first plating layer 23 is, for example, a Cu plating layer. The second plating layer 24 is, for example, a Ni plating layer. The third plating layer 25 is, for example, a Sn plating layer. In addition, in Figure 4 , the external electrode 20 a is illustrated as an example, but the external electrode 20 b also has the same stacked structure.

[0074] Here, a description will be given of problems that arise when a low-melting-point metal is added to the internal electrode layer 12 in order to improve the high-temperature load life.

[0075] Figure 5 (A) is a cross-sectional view showing an example of a conventional multilayer ceramic capacitor 1000, showing the Figure 3 (B) shows a cross section at the same position as in (B). In multilayer ceramic capacitor 1000, internal electrode layer 112 is primarily composed of Ni and contains a low-melting-point metal. Dielectric layer 111, cover layer 113, and side edge 116 are primarily composed of a ceramic material having a perovskite structure represented by the general formula ABO3 and have substantially the same composition.

[0076] The multilayer ceramic capacitor 1000 includes a laminate 117 including a dielectric layer 111 , an internal electrode layer 112 , and a cover layer 113 , and side edges 116 covering both end surfaces of the laminate 117 in the W direction.

[0077] In this case, when the internal electrode layer 112 contains a low melting point metal, the difference between the shrinkage behavior of the dielectric layer 111 and the shrinkage behavior of the internal electrode layer 112 during firing becomes larger. Figure 5 As shown in (A), gaps 140 are formed between the W-direction ends of the internal electrode layer 112 and the side edges 116, reducing moisture resistance. The gaps 140 are gaps whose dimensions in the W or T directions are greater than the average thickness of the internal electrode layer 112.

[0078] Figure 5 (B) is a cross-sectional view illustrating a conventional multilayer ceramic capacitor 1001, showing the Figure 3(B) shows a cross section at the same location. In multilayer ceramic capacitor 1001, internal electrode layer 112 is primarily composed of Ni and also contains a low-melting-point metal. Dielectric layer 111, cover layer 113, and side edge 116a are primarily composed of a ceramic material having a perovskite structure represented by the general formula ABO3. However, the Mg concentration in side edge 116a is higher than in dielectric layer 111 and cover layer 113.

[0079] exist Figure 5 In the multilayer ceramic capacitor 1001 shown in FIG. 1 (B), during firing, oxides 150 containing Ni and Mg are formed at both ends of the internal electrode layer 112 in the W direction, causing the ends of the internal electrode layer 112 to expand, thereby suppressing voids. This can prevent a decrease in moisture resistance.

[0080] On the other hand, when the external electrode 120a is sintered, the internal electrode layer 112 reacts with the external electrode 120a, and the metal component of the external electrode 120a diffuses toward the Ni side of the internal electrode layer 112, causing the internal electrode layer 112 to expand. For example, when the main component metal of the base layer of the external electrode 20a is different from the main component metal of the internal electrode layer 112, diffusion is likely to occur. In particular, when the main component metal of the base layer is Cu and the main component metal of the internal electrode layer 112 is Ni, diffusion is likely to occur. Due to the expansion of the internal electrode layer 112, stress is generated outward in the covering layer 113 and the side edge 116a, causing cracks. When a low-melting-point metal such as Sn is added to the internal electrode layer 112, diffusion from the external electrode 120a is promoted. When the external electrode 120a is sintered, cracks such as the following may occur in the portion covered by the external electrode 120a and where the covering layer 113 overlaps with the side edge 116a (the corner near the external electrode). Figure 6 That crack 160.

[0081] Therefore, the multilayer ceramic capacitor 100 of this embodiment has a structure capable of improving high-temperature load life while suppressing degradation of moisture resistance caused by gaps formed between the W-direction ends of the internal electrode layer 12 and the side edges 16 and degradation of moisture resistance caused by cracks.

[0082] Specifically, the cap layer 13 has a higher Mg concentration than the dielectric layer 11 and the side edges 16. Figure 3As shown in (A), in the region corresponding to the capacitor portion 14, the outermost internal electrode layer 12 in the stacking direction has oxides 50 containing Ni and Mg at both ends in the W direction. Therefore, the gaps 40 between the both ends in the W direction of the outermost internal electrode layer 12 and the side edges 16 are suppressed. Therefore, it is possible to suppress a decrease in moisture resistance in the portion of the laminated sheet 10 not covered by the external electrodes 20a and 20b.

[0083] In addition, if Figure 3 As shown in (B), at edge 15, the outermost internal electrode layer 12 of the internal electrode layers 12 connected to external electrode 20a has oxides 50 containing Ni and Mg at both ends in the W direction. Although the lowermost internal electrode layer 12 of the internal electrode layers 12 connected to external electrode 20a does not contact cover layer 13, which has a high Mg concentration, the distance between the lowermost internal electrode layer 12 and cover layer 13 is short, and there is no internal electrode layer 12 connected to external electrode 20b. Therefore, due to the effect of Mg added to cover layer 13, oxides 50 containing Ni and Mg can also be formed at both ends in the W direction of the lowermost internal electrode layer 12. The same applies to the uppermost internal electrode layer 12 of the internal electrode layers 12 connected to external electrode 20b. This can suppress a decrease in moisture resistance at edge 15.

[0084] In addition, if Figure 3 As shown in (B), the ends in the W direction of the internal electrode layers 12 other than the topmost and bottommost internal electrode layers 12 connected to the external electrodes 20a do not have oxides containing Ni and Mg and are adjacent to the gaps 40 formed between them and the side edges 16. Therefore, even if the internal electrode layers 12 expand due to diffusion of the main component metal of the base layer 21 of the external electrodes 20a, generating outward stress in the cover layer 13 and the side edges 16, the gaps 40 can alleviate the stress, thereby suppressing the occurrence of cracks. This can also suppress the reduction in moisture resistance caused by the occurrence of cracks.

[0085] The Mg concentration in the covering layer 13 is, for example, 1.5 at % or more. Here, the Mg concentration in the covering layer 13 refers to the amount of Mg (at %) in the entire covering layer 13 when the B-site element in the covering layer 13 is 100 at %.

[0086] From the perspective of promoting oxidation of Ni, the main component metal of internal electrode layer 12, and sufficiently oxidizing and expanding both ends of outermost internal electrode layer 12 in the W direction, the Mg concentration in cover layer 13 is preferably 2.0 at % or higher. On the other hand, from the perspective of suppressing a decrease in dielectric constant due to excessive diffusion of Mg into dielectric layer 11, the Mg concentration in cover layer 13 is preferably 5 at % or lower, and more preferably 2.5 at % or lower.

[0087] From the perspective of preventing a decrease in dielectric constant, the Mg concentration in dielectric layer 11 and side edges 16 is preferably 0.5 at% or less, and more preferably 0.25 at% or less. The Mg concentration in dielectric layer 11 refers to the amount of Mg (at%) in the entire dielectric layer 11 sandwiched between two adjacent internal electrode layers 12, when the B-site element in dielectric layer 11 is assumed to be 100 at%. Furthermore, the Mg concentration in side edges 16 refers to the amount of Mg (at%) in the entire side edges 16, when the B-site element in side edges 16 is assumed to be 100 at%.

[0088] Next, a method for manufacturing the multilayer ceramic capacitor 100 according to the first embodiment will be described. Figure 7 1 is a flowchart illustrating a method for manufacturing the multilayer ceramic capacitor 100. Figure 8 1 is a diagram illustrating an outline of a method for manufacturing the multilayer ceramic capacitor 100 .

[0089] (Raw material powder production process)

[0090] First, a dielectric material for forming dielectric layer 11 is prepared. The A-site element and B-site element contained in dielectric layer 11 are generally contained in dielectric layer 11 in the form of a sintered body of ABO3 particles. For example, BaTiO3 is a tetragonal compound having a perovskite structure and exhibits a high dielectric constant. This BaTiO3 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 ceramics as the main component of dielectric layer 11, such as solid-phase methods, sol-gel methods, and hydrothermal methods. In this embodiment, any of these methods can be used.

[0091] The resulting ceramic powder may be added with a predetermined additive compound depending on the intended purpose. Examples of additive compounds include oxides of Mg, Mn, Mo, V, Cr, and rare earth elements (Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb), oxides containing Co, Ni, Li, B, Na, K, or Si, and glasses containing Co, Ni, Li, B, Na, K, or Si. Among these, SiO2 primarily serves as a sintering aid.

[0092] For example, a ceramic material is prepared by wet-mixing a compound containing an additive compound with a ceramic raw material powder, drying and pulverizing the mixture. For example, the ceramic material obtained as described above can be subjected to pulverization treatment as needed to adjust the particle size, or the particle size can be adjusted by combining it with a classification treatment. Through the above-mentioned process, a dielectric material is obtained. In addition, from the viewpoint of preventing a decrease in the dielectric constant, the Mg concentration in the dielectric material is preferably 0.5 at% or less, more preferably 0.25 at% or less. The Mg concentration in the dielectric material refers to the Mg amount (at%) when the B-site element in the dielectric material is set to 100 at%.

[0093] Next, an edge material for forming the side edge 16 is prepared. The edge material contains ceramics, which are the main component of the side edge 16. As the main component ceramic, for example, BaTiO3 powder is prepared. BaTiO3 powder can be prepared by the same process as the dielectric material. To the obtained BaTiO3 powder, a prescribed additive compound can be added according to the purpose. Examples of additive compounds include oxides of Zr, Ca, Sr, Mg, Mn, V, Cr, and rare earth elements, and oxides or glasses of Co, Ni, Li, B, Na, K, and Si. When Mg is added to the edge material, from the viewpoint of preventing a decrease in the dielectric constant, the Mg concentration in the edge material is preferably 0.5 at% or less, and more preferably 0.25 at% or less, when the concentration of the B-site element is set to 100 at%. The Mg concentration in the edge material refers to the amount of Mg (at%) when the B-site element in the edge material is set to 100 at%.

[0094] Next, a covering material for forming the covering layer 13 is prepared. The covering material contains ceramics, which are the main component of the covering layer 13. As the main component ceramic, for example, BaTiO3 powder is prepared. BaTiO3 powder can be prepared by the same process as the dielectric material. Mg is added to the obtained BaTiO3 powder. In addition to Mg, other additive compounds can also be added. Examples of other additive compounds include oxides of Zr, Ca, Sr, Mn, V, Cr, and rare earth elements, as well as oxides or glasses of Co, Ni, Li, B, Na, K, and Si. The Mg concentration in the covering material is adjusted to be higher than the Mg concentration in the dielectric material and the Mg concentration in the edge material.

[0095] The Mg concentration in the coating material is set to, for example, 1.5 at % or more. The Mg concentration in the coating material refers to the amount of Mg (at %) when the B-site element in the coating material is set to 100 at %.

[0096] To promote oxidation of Ni, the main metal component of internal electrode layer 12, and to sufficiently oxidize and expand both ends of outermost internal electrode layer 12 in the W direction, the Mg concentration in the covering material is preferably 2.0 at % or higher. On the other hand, to suppress a decrease in dielectric constant due to excessive diffusion of Mg into dielectric layer 11, the Mg concentration in the covering material is preferably 5 at % or lower, and more preferably 2.5 at % or lower.

[0097] (Lamination process)

[0098] Next, 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 production step and wet-mixed. The resulting slurry is applied to a substrate using, for example, a die coating method or a doctor blade method and dried to obtain a dielectric green sheet 51. The substrate is, for example, a polyethylene terephthalate (PET) film.

[0099] Then, if Figure 8 As shown in the example, an internal electrode pattern 52 is formed on a dielectric green sheet 51. The dielectric green sheet 51 on which the internal electrode pattern 52 is formed is used as a lamination unit. The width of the internal electrode pattern 52 in the W direction is made equal to the width of the dielectric green sheet 51 in the W direction. Figure 8 In FIG. 5 , the internal electrode pattern 52 is indicated by hatching.

[0100] The internal electrode patterns 52 are formed using a metal paste containing nickel, the main component metal of the internal electrode layer 12, and containing a low-melting-point metal having a melting point of 700°C or less. The concentration of the low-melting-point metal in the metal paste is, for example, 1 at%. The concentration of the low-melting-point metal in the metal paste refers to the amount (at%) of the low-melting-point metal when the amount of nickel in the metal paste is 100 at%. If multiple low-melting-point metals are used, the added concentration of the low-melting-point metal refers to the total amount of the multiple low-melting-point metals.

[0101] To improve the electrical barrier at the interface between dielectric layer 11 and internal electrode layer 12, the concentration of the low-melting-point metal in the metal paste is preferably 0.3 at% or higher, more preferably 0.5 at% or higher. On the other hand, to prevent excessive shrinkage of internal electrode layer 12, the concentration of the low-melting-point metal in the metal paste is preferably 5 at% or lower, more preferably 3 at% or lower. The internal electrode pattern 52 can be formed by printing, sputtering, vapor deposition, or other methods.

[0102] Next, the dielectric green sheet 51 is peeled off from the substrate, and Figure 8 As illustrated, the stacking units are stacked.

[0103] 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. The resulting slurry is applied to a substrate using, for example, a die coating method or a doctor blade method and dried to obtain a strip-shaped cover sheet 53 having a thickness of, for example, 10 μm or less. The width of the cover sheet 53 in the W direction is aligned with the width of the dielectric green sheet 51 in the W direction.

[0104] like Figure 8 As illustrated, a predetermined number (eg, 2 to 10 layers) of cover sheets 53 are stacked on top and bottom of a laminated body obtained by stacking the lamination units and then thermocompression-bonded.

[0105] Next, a binder such as polyvinyl butyral (PVB) resin, an organic solvent such as ethanol or toluene, and a plasticizer are added to the edge material obtained in the raw material powder production step and wet-mixed. The resulting slurry is applied to a substrate using, for example, a die coating method or a doctor blade method and dried to obtain a strip-shaped side edge sheet 54 having a thickness of, for example, 10 μm or less.

[0106] Next, a plurality of side edge sheets 54 are attached to both side surfaces of a laminated body obtained by laminating the cover sheet 53 and the lamination units.

[0107] (Firing process)

[0108] Then, at an oxygen partial pressure of 10 -5 ~10 -8 Atm reducing atmosphere, sinter at 1100-1300℃ for 10 minutes to 2 hours.

[0109] (Reoxidation treatment process)

[0110] Thereafter, a reoxidation treatment may be performed at 600° C. to 1000° C. in an N 2 gas atmosphere.

[0111] (Coating process)

[0112] Next, a metal paste mainly composed of a metal such as Cu or Ni, which will become the base layer 21, is applied to the first side surface of the laminate by dipping or the like. The metal paste contains a glass component such as glass frit.

[0113] (Sintering process)

[0114] Next, the metal paste is sintered at a temperature of approximately 700° C. to 900° C. to form the base layer 21 .

[0115] (Plating treatment process)

[0116] Then, a metal coating such as Cu, Ni, or Sn can be applied to the base layer 21 through plating. For example, a first plating layer 23, a second plating layer 24, and a third plating layer 25 are sequentially formed on the base layer 21. Thus, the multilayer ceramic capacitor 100 is completed.

[0117] According to the manufacturing method of this embodiment, Mg is added to the covering material forming the covering layer 13. Therefore, during the firing process, oxides containing Ni and Mg are formed at the W-direction ends of the outermost internal electrode layer 12, causing the W-direction ends of the internal electrode layer 12 to expand. This prevents the formation of voids between the W-direction ends of the outermost internal electrode layer 12 and the side edges 16, thereby suppressing a decrease in moisture resistance. Furthermore, oxides containing Ni and Mg are not formed at the W-direction ends of the internal electrode layers 12 other than the outermost internal electrode layer 12, but rather voids 40 are formed. Consequently, even if expansion of the internal electrode layer 12 due to diffusion of the main component metal of the external electrodes 20a and 20b generates outward stress in the covering layer 13 and the side edges 16, the voids 40 can alleviate the stress, thus suppressing the occurrence of cracks. Furthermore, the internal electrode pattern 52 uses a metal paste containing Ni, the main component metal of the internal electrode layer 12 , and added with a low melting point metal. This improves the electrical barrier at the interface between the dielectric layer 11 and the internal electrode layer 12 , thereby increasing the high-temperature load life.

[0118] (Second embodiment)

[0119] In the first embodiment described above, the outermost internal electrode layer 12 has oxides containing Ni and Mg at both ends in the W direction. However, a predetermined number of internal electrode layers 12, including the outermost internal electrode layer 12, may also have oxides containing Ni and Mg at both ends in the W direction. In other words, one or more internal electrode layers 12 starting from the outermost layer may also have oxides containing Ni and Mg at both ends in the W direction.

[0120] Figure 9 (A) is a partial cross-sectional perspective view of a multilayer ceramic capacitor 101 according to the second embodiment. Figure 9 (B) is a cross-sectional view of the multilayer ceramic capacitor 101 . Figure 9 (B) indicates that Figure 3 A cross section at the same position as (B).

[0121] like Figure 9As shown in FIG. 1B , in the multilayer ceramic capacitor 101 of the second embodiment, the plurality of dielectric layers 11 include an inner dielectric layer 11a and an outer dielectric layer 11b. The outer dielectric layer 11b is one or more dielectric layers 11 from the outermost layer among the plurality of dielectric layers 11 and is located outward of the inner dielectric layer 11a in the stacking direction (T direction). The region where the inner dielectric layer 11a and the internal electrode layer 12 overlap is referred to as the inner region 71, and the region where the outer dielectric layer 11b and the internal electrode layer 12 overlap is referred to as the outer region 72.

[0122] The main phases of inner dielectric layer 11a and outer dielectric layer 11b are the same as those of dielectric layer 11 in the first embodiment, but the Mg concentration of outer dielectric layer 11b is higher than that of inner dielectric layer 11a. Furthermore, the Mg concentration of outer dielectric layer 11b is higher than that of side edge 16. The Mg concentration of outer dielectric layer 11b may be the same as or different from that of cover layer 13, as long as it is higher than that of inner dielectric layer 11a and side edge 16.

[0123] The Mg concentration in outer dielectric layer 11b is, for example, 1.5 at% or greater. To promote oxidation of Ni, the primary metal component of internal electrode layer 12, and to sufficiently oxidize and expand both ends of internal electrode layer 12 in the W direction that contact outer dielectric layer 11b, the Mg concentration in outer dielectric layer 11b is preferably 2.0 at% or greater. On the other hand, to suppress a decrease in dielectric constant due to excessive diffusion of Mg into inner dielectric layer 11a, the Mg concentration in outer dielectric layer 11b is preferably 5 at% or less, and more preferably 2.5 at% or less.

[0124] The number of stacked outer dielectric layers 11b having a high Mg concentration in each outer region 72 is preferably 5% or more of the total number of stacked layers from the perspective of improving moisture resistance at the corners, and is preferably 20% or less of the total number of stacked layers from the perspective of suppressing cracks at the corners caused by expansion of the internal electrode layer 12.

[0125] The other structures are the same as those of the first embodiment, and therefore detailed descriptions are omitted.

[0126] Because the Mg concentration in outer dielectric layer 11b is higher than that in inner dielectric layer 11a and at side edges 16, internal electrode layer 12 in contact with outer dielectric layer 11b has oxides 50 containing Ni and Mg at both ends in the W direction. This suppresses the formation of voids 40 between the W direction ends of internal electrode layer 12 and side edges 16, thereby improving moisture resistance. Furthermore, voids 40 are formed between the W direction ends of internal electrode layer 12 within inner region 71 and side edges 16. Consequently, even if expansion of internal electrode layer 12 due to diffusion of the main component metal of external electrodes 20a and 20b generates outward stress in cover layer 13 and side edges 16, the voids 40 can mitigate the stress, thus suppressing the formation of cracks.

[0127] Figure 10 1 is a diagram illustrating an outline of a method for manufacturing a multilayer ceramic capacitor 101 according to the second embodiment. Figure 10 As illustrated, the Mg concentration in the second dielectric green sheet 51b corresponding to the outer dielectric layer 11b can be higher than the Mg concentration in the first dielectric green sheet 51a corresponding to the inner dielectric layer 11a. The Mg concentration in the second dielectric green sheet 51b is, for example, 1.5 at% or higher. The Mg concentration in the second dielectric green sheet 51b refers to the amount of Mg (at%) in the entire second dielectric green sheet 51b, assuming the B-site element in the second dielectric green sheet 51b is 100 at%.

[0128] To promote oxidation of Ni, the main metal component of the internal electrode layer 12, and to sufficiently oxidize and expand both ends of the internal electrode layer 12 in the W direction in contact with the second dielectric green sheet 51b, the Mg concentration in the second dielectric green sheet 51b is preferably 2.0 at% or higher. On the other hand, to suppress a decrease in dielectric constant due to excessive diffusion of Mg into the inner dielectric layer 11a, the Mg concentration in the second dielectric green sheet 51b is preferably 5 at% or lower, and more preferably 2.5 at% or lower.

[0129] (Third embodiment)

[0130] In the multilayer ceramic capacitor 102 of the third embodiment, the width of the internal electrode layer 12 is varied. Figure 11 (A) and Figure 11 (B) is a partial cross-sectional perspective view of the multilayer ceramic capacitor 102 according to the third embodiment. Figure 12 102 is a cross-sectional view of the multilayer ceramic capacitor 102 .

[0131] like Figure 12As shown, the internal electrode layer 12 connected to the external electrode 20a has: a first region 121 (connecting portion) having a width W1 connected to the external electrode 20a in a region corresponding to the end edge 15; and a second region 122 having a width W2 in a region corresponding to the capacitor portion 14. Width W1 is smaller than width W2. Width W1 and width W2 are widths in the W direction. According to this structure, the contact area between the external electrodes 20a, 20b and the internal electrode layer 12 is reduced, thereby suppressing the diffusion from the external electrodes 20a, 20b to the internal electrode layer 12. As a result, the generation of cracks can be suppressed. In addition, in the internal electrode layer 12 connected to the external electrode 20b, a first region 121 having a width W1 and a second region 122 having a width W2 are also provided.

[0132] For example, when W1 / W2 is small, the connectivity between the external electrodes 20a, 20b and the internal electrode layer 12 decreases, potentially preventing good electrical conduction. Therefore, it is preferable to set a lower limit for W1 / W2. On the other hand, when W1 / W2 is large, the contact area between the external electrodes 20a, 20b and the internal electrode layer 12 may not be sufficiently reduced. Therefore, it is preferable to set an upper limit for W1 / W2. Based on the above, W1 / W2 is preferably at least 1 / 2, more preferably at least 2 / 3. Furthermore, W1 / W2 is preferably at most 4 / 5, more preferably at most 3 / 4.

[0133] Here, if Figure 11 (A) and Figure 12 As shown, the dimension of the external electrodes 20a and 20b extending in the L direction from both end surfaces of the laminate sheet 10 is referred to as dimension e. From the perspective of suppressing cracks in the corners, the dimension of the first region 121 in the L direction is preferably 1 / 3 or more of dimension e, more preferably 1 / 2 or more.

[0134] Furthermore, in the third embodiment, the Mg concentration of the side edges 16 a is set higher than the Mg concentration of the dielectric layer 11. Therefore, in the third embodiment, the Mg concentration of the cover layer 13 and the Mg concentration of the side edges 16 a are set higher than the Mg concentration of the dielectric layer 11. The Mg concentration of the cover layer 13 and the Mg concentration of the side edges 16 a may be the same or different.

[0135] The Mg concentration at side edge 16a is, for example, 1.5 at% or greater. To promote oxidation of Ni, the primary metal component of internal electrode layer 12, and to sufficiently oxidize and expand both ends of internal electrode layer 12 in the W direction that contact side edge 16a, the Mg concentration at side edge 16a is preferably 2.0 at% or greater. On the other hand, to suppress a decrease in dielectric constant due to excessive diffusion of Mg into dielectric layer 11, the Mg concentration at side edge 16a is preferably 5 at% or less, and more preferably 2.5 at% or less.

[0136] Figure 13 (A) and Figure 13 (B) is a cross-sectional view of the multilayer ceramic capacitor 102 . Figure 13 The cross section of (A) is Figure 3 The cross section at the same position as (A) is Figure 13 The cross section of (B) is Figure 3 A cross section at the same position as (B).

[0137] The Mg concentration of the side edge 16a is higher than that of the dielectric layer 11. Therefore, Figure 13 As shown in (A), the internal electrode layer 12 in the region corresponding to the capacitor portion 14 has an oxide 50 containing Ni and Mg at both ends in the W direction. As a result, in the region corresponding to the capacitor portion 14, it is possible to suppress the formation of gaps between both ends in the W direction of the internal electrode layer 12 and the side edge 16a, thereby improving moisture resistance.

[0138] On the other hand, Figure 13 As shown in FIG. 1B , at edge 15, the top and bottom internal electrode layers 12 connected to external electrode 20a have oxides 50 containing Ni and Mg at their W-direction ends due to Mg in cover layer 13. A gap 40 is formed between the W-direction ends of the remaining internal electrode layers 12 and dielectric layer 11. This improves moisture resistance, and even if outward stress is generated in cover layer 13 and side edge 16 due to expansion of the internal electrode layers 12 caused by diffusion of Cu, the main component metal of external electrodes 20a and 20b, the gap 40 can alleviate the stress and suppress the occurrence of cracks.

[0139] Figure 14 1 is a diagram illustrating an outline of a method for manufacturing a multilayer ceramic capacitor 102 according to a third embodiment. Figure 14 As illustrated, the dielectric green sheets 51 having internal electrode patterns 52a with widths W1 and W2 can be stacked, and side edge sheets 54a having a higher Mg concentration than the dielectric green sheets 51 are attached to both side surfaces in the W direction of the stack.

[0140] The Mg concentration of the side edge piece 54a is, for example, 1.5 at % or more. The Mg concentration of the side edge piece 54a refers to the Mg amount (at %) in the entire side edge piece 54a when the B-site element of the side edge piece 54a is 100 at %.

[0141] To promote oxidation of Ni, the main metal component of the internal electrode layer 12, and to sufficiently oxidize and expand both ends of the internal electrode layer 12 in the W direction that are in contact with the side edge piece 54a, the Mg concentration of the side edge piece 54a is preferably 2.0 at% or higher. On the other hand, to suppress a decrease in the dielectric constant caused by excessive diffusion of Mg into the dielectric layer 11, the Mg concentration of the side edge piece 54a is preferably 5 at% or lower, and more preferably 2.5 at% or lower.

[0142] (Fourth embodiment)

[0143] In the third embodiment, all the internal electrode layers 12 have the first region 121 and the second region 122 , but a part of the internal electrode layers 12 may have the first region 121 and the second region 122 .

[0144] Figure 15 (A) and Figure 15 (B) is a partial cross-sectional perspective view of the multilayer ceramic capacitor 103 according to the fourth embodiment. Figure 16 (A) and Figure 16 (B) is a cross-sectional view of the multilayer ceramic capacitor 103 . Figure 16 (A) and Figure 16 (B) are respectively Figure 3 (A) and Figure 3 A cross section at the same position as (B).

[0145] In multilayer ceramic capacitor 103, the multiple internal electrode layers 12 include inner internal electrode layers 12a and outer internal electrode layers 12b. The outer internal electrode layers 12b are a predetermined number of internal electrode layers 12, starting from the outermost layer, while the inner internal electrode layers 12a are the internal electrode layers 12 other than the outer internal electrode layers 12b. The outer internal electrode layers 12b are located outward of the inner internal electrode layers 12a in the stacking direction. The region where the dielectric layer 11 and the inner internal electrode layers 12a overlap is referred to as inner region 73, while the region where the dielectric layer 11 and the outer internal electrode layers 12b overlap is referred to as outer region 74.

[0146] Similar to the internal electrode layer 12 of the third embodiment, the outer internal electrode layer 12b has a first region 121 (connection portion) having a width W1 connected to the external electrode 20a in the region corresponding to the edge 15, and a second region 122 having a width W2 in the region corresponding to the capacitor portion 14. Width W1 is smaller than width W2. In the inner internal electrode layer 12a, width W1 in the region corresponding to the edge 15 is equal to width W2 in the region corresponding to the capacitor portion 14.

[0147] In the fourth embodiment, similarly to the third embodiment, the Mg concentration in the side edge 16a is higher than the Mg concentration in the dielectric layer 11. Therefore, Figure 16 As shown in (A), the inner internal electrode layer 12a and the outer internal electrode layer 12b in the region corresponding to the capacitor portion 14 have oxides 50 containing Ni and Mg at both ends in the W direction. As a result, in the region corresponding to the capacitor portion 14, gaps between both ends in the W direction of the internal electrode layer 12 and the side edge 16a can be suppressed, thereby improving moisture resistance.

[0148] Furthermore, at edge 15, due to the Mg in cover layer 13, at least the uppermost and lowermost internal electrode layers 12 (outer internal electrode layers 12b) of the outer internal electrode layers 12b connected to external electrode 20a have oxides 50 containing Ni and Mg at their ends in the W direction, and the W direction ends of the other outer internal electrode layers 12b are adjacent to voids 40. Furthermore, due to the Mg in side edges 16a, inner internal electrode layers 12a have oxides 50 containing Ni and Mg at both ends in the W direction. This improves moisture resistance, and even if stress is generated outward in cover layer 13 and side edges 16a due to expansion of internal electrode layers 12 caused by diffusion of the main component metal of external electrodes 20a, 20b, the stress can be relieved by voids 40, thereby suppressing the occurrence of cracks.

[0149] Furthermore, in the multilayer ceramic capacitor 103 of the fourth embodiment, the inner internal electrode layer 12a has a constant width W2 in the W direction, thereby reducing poor connection between the outer electrodes 20a, 20b and the inner internal electrode layer 12a.

[0150] The Mg concentration at side edge 16a is, for example, 1.5 at% or greater. To promote oxidation of Ni, the primary metal component of internal electrode layer 12, and to sufficiently oxidize and expand both ends of internal electrode layer 12 in the W direction that contact side edge 16a, the Mg concentration at side edge 16a is preferably 2.0 at% or greater. On the other hand, to suppress a decrease in dielectric constant due to excessive diffusion of Mg into dielectric layer 11, the Mg concentration at side edge 16a is preferably 5 at% or less, and more preferably 2.5 at% or less.

[0151] Figure 17 1 is a diagram showing an overview of a method for manufacturing a multilayer ceramic capacitor 103 according to a fourth embodiment. Figure 17As shown, in the manufacturing process of the multilayer ceramic capacitor 103, dielectric green sheets 51 having internal electrode patterns 52a corresponding to outer internal electrode layers 12b having a width W1 smaller than a width W2 are stacked. On top of these, dielectric green sheets 51 having internal electrode patterns 52 corresponding to inner internal electrode layers 12a having a constant dimension in the W direction (widths W1 and W2 being equal) are stacked. Furthermore, a dielectric green sheet 51 having internal electrode patterns 52a is stacked on top of these. Next, side edge sheets 54a having a higher Mg concentration than the dielectric green sheets 51 are attached to both side surfaces of the stack in the W direction.

[0152] The Mg concentration of the side edge sheet 54a is, for example, 1.5 at% or greater. To promote oxidation of Ni, the primary metal component of the internal electrode layer 12, and to sufficiently oxidize and expand both ends of the internal electrode layer 12 in the W direction that contact the side edge sheet 54a, the Mg concentration of the side edge sheet 54a is preferably 2.0 at% or greater. On the other hand, to suppress a decrease in dielectric constant due to excessive diffusion of Mg into the dielectric layer 11, the Mg concentration of the side edge sheet 54a is preferably 5 at% or less, and more preferably 2.5 at% or less.

[0153] In the third and fourth embodiments, the side edge 16 a may have substantially the same Mg concentration as that of the dielectric layer 11 .

[0154] In addition, in the above embodiments, a multilayer ceramic capacitor is described as an example of a ceramic electronic component, but the present invention is not limited thereto. For example, the structure of the above embodiments can also be applied to other ceramic electronic components such as a varistor and a thermistor.

[0155] Example

[0156] Next, multilayer ceramic capacitors according to the respective embodiments were produced and their characteristics were examined.

[0157] (Example 1)

[0158] In Example 1, the multilayer ceramic capacitor described in the first embodiment was fabricated. First, a slurry containing BaTiO3 as its main component was prepared and coated to produce dielectric green sheets. The Mg concentration in the dielectric green sheets was 0 at%. Internal electrode patterns were printed on each dielectric green sheet. Ni powder was used for the internal electrode patterns, and Sn powder was added at a concentration of 1.0 at%. The resulting stacking units were stacked in the T direction for 260 layers to form a laminate.

[0159] A slurry containing BaTiO3 as a main component was prepared and applied to obtain a cover sheet. Mg was added to the cover sheet at 1.5 at%. A plurality of cover sheets were stacked on top and bottom of the stack in the stacking direction and pressure-bonded.

[0160] A slurry with BaTiO3 as the main component is mixed and coated to obtain side edge sheets. The Mg concentration of the side edge sheets is 0at%. Multiple side edge sheets are respectively attached to both ends of the stacked body in the W direction of the stacked unit, and then the adhesive is removed. Then, it is fired and reoxidized. A metal paste with Cu as the main component is applied to both end surfaces of the obtained stacked sheet, and sintered at about 800°C. Thereafter, Ni and Sn plating is performed on the surface. After these processes, a 0603-shaped (length L: 0.6mm, width W: 0.3mm, height T: 0.3mm) stacked ceramic capacitor with 260 internal electrode layers is produced.

[0161] In the fired multilayer ceramic capacitor, the thickness of each internal electrode layer is 0.5 μm, and the thickness of each dielectric layer is 0.5 μm. The thickness of each cover layer in the T direction is 20 μm. The thickness of each side edge in the W direction is 20 μm. The width of each internal electrode layer in the W direction (W1 = W2) is 260 μm. The dimension e of each external electrode extending in the L direction from both end faces of the laminate is 0.15 mm.

[0162] (Example 2)

[0163] In Example 2, the multilayer ceramic capacitor described in the second embodiment was produced.

[0164] First, a slurry primarily composed of BaTiO₃ was prepared and applied to produce first dielectric green sheets. The Mg concentration in the first dielectric green sheets was 0 at%. Internal electrode patterns were then printed on each first dielectric green sheet. Ni powder was used for the internal electrode patterns, with Sn powder added. The Sn concentration was 1.0 at%.

[0165] Next, a slurry containing BaTiO₃ as its main component was mixed and applied to produce second dielectric green sheets. The Mg concentration in the second dielectric green sheets was 1.5 at%. Internal electrode patterns were printed on each second dielectric green sheet. Ni powder was used for the internal electrode patterns, with Sn powder added. The Sn concentration was 1.0 at%.

[0166] 25 layers of the second dielectric green sheet stacking unit were stacked, 210 layers of the first dielectric green sheet stacking unit were stacked thereon, and 25 layers of the second dielectric green sheet stacking unit were stacked thereon to obtain a stacked body. Other conditions were the same as in Example 1.

[0167] (Example 3)

[0168] In Example 3, the multilayer ceramic capacitor described in the third embodiment was fabricated. The width W2 of each internal electrode layer in the W direction was increased in the capacitor portion, while the width W1 in the W direction was decreased at the edge. The width W2 of the internal electrode layer in the capacitor portion was 260 μm, while the width W1 of the internal electrode layer at the edge was 200 μm. Furthermore, the dimension of the first region of width W1 in the L direction was 0.08 mm.

[0169] The Mg concentration in the side edge sheet was 1.5 at %. Other conditions were the same as those in Example 1.

[0170] (Example 4)

[0171] In Example 4, the multilayer ceramic capacitor described in the fourth embodiment was produced. In each outer internal electrode layer, the width W2 in the W direction was increased in the capacitor portion, and the width W1 in the W direction was reduced in the end edge. The width W2 of the outer internal electrode layer in the capacitor portion was 260 μm, and the width W1 of the outer internal electrode layer in the end edge was 200 μm. In addition, the dimension in the L direction of the first region of width W1 was 0.08 mm. In each inner internal electrode layer, the width in the W direction (W1 = W2) was 260 μm. Other conditions were the same as in Example 3.

[0172] (Comparative Example)

[0173] In the comparative example, the Mg concentration of the cover sheet was set to 0 at %, and the Mg concentration of the side edge sheet was set to 1.5 at %. Other conditions were the same as those in Example 1.

[0174] Table 1 shows the conditions of Examples 1 to 4 and Comparative Example.

[0175] [Table 1]

[0176]

[0177]

[0178] For 100 samples each of the comparative example and examples 1 to 4, the observation was equivalent to Figure 3 Cross section (B). In the comparative example, cracks were observed at at least one corner in more than half of the samples. In Examples 1 to 4, cracks were not observed at the corners in any of the samples.

[0179] It can be considered that the reason why no cracks were confirmed in Examples 1 to 4 is that a gap was formed in the end edge between the end of a part of the internal electrode layer in the W direction and the side edge, or between the end of a part of the internal electrode layer in the W direction and the dielectric layer, thereby alleviating the stress generated in the covering layer and the side edge.

[0180] Furthermore, it is conceivable that in the comparative example, oxides containing Ni and Mg were formed at the ends of each internal electrode layer in the W direction, and no gap was formed between the ends and the side edges. Therefore, the stress generated in the cover layer and the side edges could not be relieved, resulting in cracks.

[0181] 100 samples each of the comparative example and Examples 1-4 were prepared and subjected to humidity reliability testing. Specifically, a voltage of 6.3V was applied to each sample for 1000 hours in an environment of 85°C and 85% relative humidity. The insulation resistance of each sample was measured. Samples whose insulation resistance after the humidity reliability test decreased by more than two orders of magnitude compared to the insulation resistance before the test were considered unacceptable, and the number of unacceptable samples was counted.

[0182] In the comparative example, the number of failed samples was 50 or more. In Examples 1 and 2, the number of failed samples was 10 or less. In Examples 3 and 4, the number of failed samples was 0.

[0183] It can be considered that the reason why the number of unqualified samples in Examples 1 to 4 is less than 10 is because an oxide containing Ni and Mg is formed at the end of the W direction of one or more internal electrode layers from the outermost layer, thereby preventing moisture from invading from the side edge and the covering layer, and no cracks are generated at the corners as described above.

[0184] On the other hand, in the comparative examples, cracks occurred at the corners, which presumably led to deterioration in moisture resistance, and more than half of the samples failed.

[0185] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

[0186] Description of Reference Numerals

[0187] 10 laminated sheet, 11 dielectric layer, 12 internal electrode layer, 13 cover layer, 14 capacitor portion, 15 end edge, 16 side edge, 20a, 20b external electrodes, 21 base layer, 22 plating layer, 23 first plating layer, 24 second plating layer, 25 third plating layer, 51 dielectric green sheet, 52 internal electrode pattern, 53 cover sheet, 54 side edge sheet, 100 laminated ceramic capacitor, 121 first region, 122 second region.

Claims

1. A ceramic electronic component, characterized in that: include: A laminate sheet having a substantially rectangular parallelepiped shape, comprising a laminate body and a pair of side edges covering two opposing side surfaces of the laminate body, wherein the laminate body comprises a pair of covering layers composed mainly of ceramics provided above and below a laminate structure in which a plurality of dielectric layers composed mainly of ceramics and a plurality of internal electrode layers composed mainly of Ni are alternately stacked; and A pair of external electrodes provided on the first and second end surfaces facing each other in the substantially rectangular parallelepiped shape has a structure in which a plating layer is provided on a base layer. The plurality of internal electrode layers are alternately exposed on the first end surface and the second end surface, Each of the plurality of internal electrode layers contains a metal component having a melting point of 700° C. or less, The Mg concentration of the pair of cap layers is higher than the Mg concentration of the plurality of dielectric layers, At least the outermost internal electrode layer among the plurality of internal electrode layers has an oxide containing Ni and Mg at both ends in the width direction. In a region where internal electrode layers connected to the same external electrode face each other without interposing internal electrode layers connected to different external electrodes, both ends in the width direction of at least some of the plurality of internal electrode layers are adjacent to the gap.

2. The ceramic electronic component according to claim 1, wherein: The main component of the base layer is Cu.

3. The ceramic electronic component according to claim 1 or 2, characterized in that: The Mg concentration of the coating layer is 1.5 at% or more. The Mg concentration of the dielectric layer is less than 0.5 at %.

4. The ceramic electronic component according to claim 1 or 2, characterized in that: The metal component includes any one of Ga, In, Sn, Bi, Pb, and Zn.

5. The ceramic electronic component according to claim 1 or 2, wherein: The Mg concentration of the side edge is lower than the Mg concentration of the capping layer.

6. The ceramic electronic component according to claim 5, wherein: The Mg concentration of the coating layer is 1.5 at% or more. The Mg concentration of the side edge is 0.5 at % or less.

7. The ceramic electronic component according to claim 1 or 2, characterized in that: A predetermined number of dielectric layers from the outermost layer among the plurality of dielectric layers have a higher Mg concentration than the other dielectric layers.

8. The ceramic electronic component according to claim 7, wherein: The Mg concentration of the predetermined number of dielectric layers starting from the outermost layer is 1.5 at % or more.

9. The ceramic electronic component according to claim 7, wherein: Among the plurality of internal electrode layers, the internal electrode layers that are in contact with a predetermined number of the dielectric layers from the outermost layer have oxides containing Ni and Mg at both ends in the width direction.

10. The ceramic electronic component according to claim 1 or 2, characterized in that: The width of the connection portion of each of the plurality of internal electrode layers connected to the external electrode is narrower than the width of other regions. The Mg concentration of the side edge is higher than the Mg concentration of the dielectric layer.

11. The ceramic electronic component according to claim 10, wherein: The Mg concentration of the side edge is greater than 1.5 at %.

12. The ceramic electronic component according to claim 10, wherein: Each of the plurality of internal electrode layers has an oxide containing Ni and Mg at the center in the longitudinal direction and at both ends in the width direction.

13. The ceramic electronic component according to claim 1 or 2, characterized in that: The plurality of internal electrode layers include: outer internal electrode layers of a first number from the outermost layer; and inner internal electrode layers located inwardly of the outer internal electrode layers in a stacking direction. The width of the connection portion of the outer internal electrode layer connected to the external electrode is narrower than the width of other regions. The width of the connection portion of the inner internal electrode layer connected to the external electrode is substantially equal to the width of the other regions. The Mg concentration of the side edge is higher than the Mg concentration of the dielectric layer.

14. The ceramic electronic component according to claim 13, wherein: The Mg concentration of the side edge is greater than 1.5 at %.

15. The ceramic electronic component according to claim 13, wherein: Each of the outer internal electrode layer and the inner internal electrode layer has an oxide containing Ni and Mg at the center in the longitudinal direction and at both ends in the width direction.

16. A method for manufacturing a ceramic electronic component, characterized in that: include: A step of obtaining a first laminate, the first laminate being formed by laminating a plurality of laminate units each having an internal electrode pattern formed on a dielectric green sheet, wherein the internal electrode pattern contains Ni as a main component and contains a metal component having a melting point of 700° C. or less; a step of obtaining a second laminate, the second laminate being obtained by laminating cover sheets above and below the first laminate in a lamination direction of the lamination units, wherein the cover sheets have a higher Mg concentration than the Mg concentration of the dielectric green sheets; a step of obtaining a third laminate, wherein the third laminate is obtained by attaching side edge sheets respectively covering the first side surface and the second side surface where the internal electrode pattern is exposed, to the second laminate; and The step of forming the base layer forms a base layer mainly composed of metal on the first end surface and the second end surface of the third stacked body that are opposite to each other, when or after the third stacked body is fired.

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