Multilayer ceramic capacitor

Abstract

Provided is a multilayer ceramic capacitor capable of suppressing defects in an external electrode.　In this multilayer ceramic capacitor 10, a base electrode layer 32 includes Cu particles 40 (conductive metal), and glass 45 that contains Si and an element α which is a main component. The element α is Ba or Sr. The glass 45 includes: surface layer glass 45a that faces the base electrode layer surface 33 of the base electrode layer 32; and internal glass 45b that is independent of the surface layer glass 45a and located inside of the base electrode layer 32 so as to not face the base electrode layer surface 33. The ratio (C content / element α content) Rs of the C content to the element α content in the surface layer glass 45a and the ratio Ri of the C content to the element α content in the internal glass 45b satisfy (expression 1). (Expression 1): (Ri-Rs) / Ri ≤ 29.5%

Description

Multilayer ceramic capacitors

[0001] The present invention relates to a multilayer ceramic capacitor.

[0002] Demand for multilayer ceramic capacitors (MLCCs) is expected to expand significantly as electronic components for automobiles, mobile phones, and the like. In recent years, there has been a demand for smaller, larger capacitance, higher reliability, and multiple terminals in multilayer ceramic capacitors, which has led to demands for thinner and flatter external electrodes in electronic components. However, as external electrodes become thinner, it has been reported that peeling and chipping of the external electrodes occur after the external electrode paste is applied and dried, especially at corners where the film thickness is thin. Therefore, there is a demand for improving the strength of the external electrode paste applied to multilayer ceramic capacitors.

[0003] Patent Document 1 discloses an external electrode paste that contains a resin containing an ethyl cellulose-based resin and an acrylic-based resin, at least partially copolymerized, a Cu filler, and a solvent, and that has an interfacial tension of 15 mN / m or more between the resin and the solvent. This external electrode paste has sufficient strength to form a dry film.

[0004] Japanese Patent Application Laid-Open No. 2021-77750

[0005] However, although the use of the external electrode paste described in Patent Document 1 can increase the strength of the dried film, defects in the external electrodes such as blisters and glass lifting may occur during the process of sintering the dried film.

[0006] SUMMARY OF THE INVENTION Therefore, a primary object of the present invention is to provide a multilayer ceramic capacitor capable of suppressing defects in the external electrodes.

[0007] A multilayer ceramic capacitor according to the present invention includes a laminate in which a plurality of ceramic layers and a plurality of internal electrode layers are alternately stacked in a predetermined stacking direction, and external electrodes connected to the plurality of internal electrode layers at portions where the plurality of internal electrode layers are exposed in the laminate. The external electrodes include base electrode layers formed on the laminate, the base electrode layers including a conductive metal and glass containing Si and an element α as a main component. The element α is Ba or Sr. The glass includes a surface glass facing the external electrode surface of the external electrode, and an inner glass that does not face the external electrode surface, is located inside the external electrode, and is independent of the surface glass. The ratio Rs of the carbon content to the element α in the surface glass (C content / element α content) and the ratio Ri of the carbon content to the element α in the inner glass satisfy the following (Equation 1): (Ri - Rs) / Ri≦29.5% (Equation 1).

[0008] The satisfaction of the above (Equation 1) means that the difference between Ri and Rs is small. In other words, the difference between the content of C (carbon) incorporated in the surface glass and the content of C incorporated in the inner glass is small. In other words, the surface glass contains the same amount of C as the inner glass.

[0009] The external electrodes on the laminate are formed by drying, degreasing, and firing an external electrode paste applied to the laminate. The external electrode paste contains a resin, a conductive metal powder, a glass powder, and a solvent. The external electrode paste is applied to the laminate and dried to form a dry film. The dried film is then degreased to form an unsintered external electrode. The unsintered external electrode is then fired to form the external electrode. The unsintered external electrode may contain residual C from the resin contained in the external electrode paste. The amount of residual C incorporated into the surface glass may be relatively small, resulting in the unsintered external electrode being fired in a state where it is in contact with the gas phase of the firing atmosphere. In this case, the C in contact with the gas phase of the firing atmosphere is converted into gas (CO2) during firing, which can cause defects such as glass lifting and blisters in the external electrode. These defects occur more frequently when the amount of residual C in the unsintered external electrode that is in contact with the gas phase of the firing atmosphere is greater. That is, a large amount of C in contact with the gas phase of the firing atmosphere is rapidly gasified by firing, and this rapid gasification induces many defects such as glass lifting and blisters.

[0010] According to the above configuration, the C in the resin is incorporated into the surface glass to the same extent as in the inner glass. This reduces the amount of C in the unsintered external electrodes that comes into contact with the gas phase of the firing atmosphere. This prevents rapid gasification of C during firing of the unsintered external electrodes, thereby providing a multilayer ceramic capacitor that can reduce defects such as glass lift and blisters in the external electrodes. Since these defects can be reduced, the external electrodes can be flattened, and it is also possible to prevent moisture and other imperfections from entering the laminate after firing through defective areas such as glass lift and blisters. This also makes it possible to reduce the size of the multilayer ceramic capacitor and improve its moisture resistance reliability.

[0011] According to the present invention, it is possible to provide a multilayer ceramic capacitor capable of suppressing defects in the external electrodes.

[0012] The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention, which proceeds with reference to the accompanying drawings.

[0013] 1 is an external perspective view showing an example of a multilayer ceramic capacitor as an electronic component according to an embodiment of the present invention. It is a cross-sectional view taken along line II-II in FIG. 1 . It is a schematic diagram showing the internal structure of the base electrode layer in FIG. 2 . (a) is a partial cross-sectional view taken along line IVa-IVa in FIG. 1 , and (b) is a partial cross-sectional view taken along line IVb-IVb in FIG. 1 . (a) to (c) are schematic diagrams showing a process of introducing residual C into glass after degreasing of the resin. (a) to (d) are diagrams for explaining a process of applying a base electrode layer paste to a laminate according to the present embodiment. It is a schematic diagram showing the internal structure of the base electrode layer of a conventional multilayer ceramic capacitor. (a) and (b) are schematic diagrams showing a process of forming a base electrode layer through a firing process for metal sintering after applying a base electrode layer paste, drying and degreasing, in a conventional method for manufacturing a multilayer ceramic capacitor. It is a schematic diagram showing an evaluation index for glass lifting. It is a schematic diagram showing a thin sample to be analyzed taken from the base electrode layer. It is an SEM image of the appearance of the sample of Example 1. 1 is a SEM image of the appearance of the sample of Comparative Example 1.

[0014] EMBODIMENTS 1. Multilayer Ceramic Capacitor A multilayer ceramic capacitor according to an embodiment of the present invention will be described below, taking a two-terminal multilayer ceramic capacitor as an example.

[0015] Fig. 1 is an external perspective view showing an example of a multilayer ceramic capacitor as an electronic component according to an embodiment of the present invention, Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1, and Fig. 3 is a schematic diagram showing the configuration of a base electrode layer.

[0016] The laminate 12 includes a plurality of stacked ceramic layers 14 and a plurality of internal electrode layers 16. The laminate 12 further includes a first main surface 12a and a second main surface 12b that face each other in a height direction x, a first side surface 12c and a second side surface 12d that face each other in a width direction y that is perpendicular to the height direction x, and a first end surface 12e and a second end surface 12f that face each other in a length direction z that is perpendicular to the height direction x and the width direction y. The corners and ridges of the laminate 12 are preferably rounded. The corners refer to the intersections of three adjacent surfaces of the laminate, and the ridges refer to the intersections of two adjacent surfaces of the laminate. Furthermore, unevenness may be formed on some or all of the first main surface 12a and the second main surface 12b, the first side surface 12c and the second side surface 12d, and the first end surface 12e and the second end surface 12f. Furthermore, the dimension of the laminate 12 in the length direction z is not necessarily longer than the dimension in the width direction y.

[0017] The laminate 12 has, in the lamination direction x connecting the first main surface 12a and the second main surface 12b, an effective layer portion 15a where the internal electrode layers 16 face each other, a first outer layer portion 15b located between the first main surface 12a and the internal electrode layer 16 closest to the first main surface 12a, and a second outer layer portion 15c located between the second main surface 12b and the internal electrode layer 16 closest to the second main surface 12b. The first outer layer portion 15b is located on the first main surface 12a side of the laminate 12, and is an assembly of multiple ceramic layers 14 located between the first main surface 12a and the internal electrode layer 16 closest to the first main surface 12a. The second outer layer portion 15c is located on the second main surface 12b side of the laminate 12, and is an assembly of multiple ceramic layers 14 located between the second main surface 12b and the internal electrode layer 16 closest to the second main surface 12b. The region sandwiched between the first outer layer portion 15b and the second outer layer portion 15c is the effective layer portion 15a.

[0018] The dimensions of the laminate 12 are not particularly limited, but it is preferable that the dimension in the length direction z is, for example, 0.2 mm or more and 32.0 mm or less, the dimension in the width direction y is, for example, 0.1 mm or more and 25.0 mm or less, and the dimension in the height direction x is, for example, 0.1 mm or more and 25.0 mm or less.

[0019] The ceramic layer 14 can be formed, for example, from a dielectric material as the ceramic material. Such a dielectric material includes a perovskite compound represented by the general formula ABO3, in which the A site is Ba. For example, a dielectric ceramic containing a component such as BaTiO3 can be used as the dielectric material. When the above-mentioned dielectric material is contained as the main component, a secondary component such as a Mn compound, an Fe compound, a Cr compound, a Co compound, or a Ni compound may be added in a smaller amount than the main component, depending on the desired characteristics of the laminate 12.

[0020] The number of ceramic layers 14, including the effective layer portion 15a and the first and second outer layer portions 15b, 15c, is preferably, for example, 15 to 450.

[0021] The thickness of the ceramic layer 14 after firing is preferably, for example, not less than 0.3 μm and not more than 10.0 μm.

[0022] When a piezoelectric ceramic material is used for the ceramic layer 14, the electronic component functions as a piezoelectric component. Specific examples of piezoelectric ceramic materials include PZT (lead zirconate titanate) ceramic materials. When a semiconductor ceramic material is used for the ceramic layer 14, the electronic component functions as a thermistor element. Specific examples of semiconductor ceramic materials include spinel ceramic materials. When a magnetic ceramic material is used for the ceramic layer 14, the electronic component functions as an inductor element. When functioning as an inductor element, the internal electrode layer 16 becomes a coil-shaped conductor. Specific examples of magnetic ceramic materials include ferrite ceramic materials.

[0023] 2, the laminate 12 has, for example, a plurality of substantially rectangular first internal electrode layers 16a and a plurality of second internal electrode layers 16b as the plurality of internal electrode layers 16. The plurality of first internal electrode layers 16a and the plurality of second internal electrode layers 16b are embedded so as to be alternately arranged at equal intervals along the lamination direction of the laminate 12. The first internal electrode layers 16a and the second internal electrode layers 16b may be arranged parallel to or perpendicular to the mounting surface.

[0024] The first internal electrode layer 16a has an end portion extending to and exposed on the first end face 12e, and the second internal electrode layer 16b has an end portion extending to and exposed on the second end face 12f.

[0025] The internal electrode layers 16 contain an appropriate conductive material, such as a metal such as Ni, Cu, Ag, Pd, or Au, or an alloy containing at least one of these metals, such as an Ag-Pd alloy. The internal electrode layers 16 may further contain dielectric particles having the same composition as the ceramic contained in the ceramic layers 14.

[0026] The thickness of the internal electrode layers 16 is preferably, for example, 0.2 μm or more and 1.5 μm or less, and the number of the internal electrode layers 16 is preferably, for example, 15 or more and 450 or less.

[0027] External electrodes 30 are disposed on the first end face 12e side and the second end face 12f side of the laminate 12. The external electrodes 30 include a first external electrode 30a and a second external electrode 30b.

[0028] The first external electrode 30a is connected to the first internal electrode layer 16a on the first end face 12e side. In this embodiment, the first external electrode 30a extends from the first end face 12e side and is arranged on a portion of the first main surface 12a side, a portion of the second main surface 12b side, a portion of the first side surface 12c side, and a portion of the second side surface 12d side. However, the first external electrode 30a may be arranged only on the first end face 12e.

[0029] The second external electrode 30b is connected to the second internal electrode layer 16b on the second end face 12f side. In this embodiment, the second external electrode 30b extends from the second end face 12f side and is arranged on a portion of the first main surface 12a side, a portion of the second main surface 12b side, a portion of the first side surface 12c side, and a portion of the second side surface 12d side. However, the second external electrode 30b may be arranged only on the second end face 12f.

[0030] In the laminate 12, capacitance is formed by the first internal electrode layer 16a and the second internal electrode layer 16b facing each other via the ceramic layer 14. Therefore, capacitance can be obtained between the first external electrode 30a connected to the first internal electrode layer 16a and the second external electrode 30b connected to the second internal electrode layer 16b, and the characteristics of a capacitor are exhibited.

[0031] The external electrode 30 includes a base electrode layer 32 and a plating layer 34 formed on a base electrode layer surface 33 of the base electrode layer 32 .

[0032] The base electrode layer 32 includes a first base electrode layer 32a and a second base electrode layer 32b.

[0033] The first base electrode layer 32a is connected to the first internal electrode layer 16a on the first end face 12e side of the laminate 12. In this embodiment, the first base electrode layer 32a extends from the first end face 12e side and is formed so as to cover parts of the surfaces on the first main face 12a side, the second main face 12b side, the first side face 12c side, and the second side face 12d side. However, the first base electrode layer 32a may be disposed only on the first end face 12e.

[0034] The second base electrode layer 32b is connected to the second internal electrode layer 16b on the second end face 12f side of the laminate 12. In this embodiment, the second base electrode layer 32b extends from the second end face 12f side and is formed so as to cover parts of the surfaces on the first main face 12a side, the second main face 12b side, the first side face 12c side, and the second side face 12d side. However, the second base electrode layer 32b may be disposed only on the second end face 12f.

[0035] As shown in FIG. 3 , the base electrode layer 32 includes glass 45 (sintered glass powder 43, described below) and a conductive metal (sintered conductive metal powder, described below; in this embodiment, sintered Cu powder 42). The glass 45 of the base electrode layer 32 is mainly composed of element α and contains at least Si. The element α in the glass 45 is Ba or Sr. The glass 45 may additionally contain at least one element selected from B, Zn, Ca, Mg, Al, Li, Bi, Na, K, Ti, Zr, Cu, Mn, Co, Ni, Fe, V, and the like. Examples of the glass 45 include Ba-Si-B-based glass, Ba-Si-B-Zn-based glass, Sr-Si-B-based glass, and Ba-Si-B-Zn-Ca-Al-based glass. The conductive metal of the base electrode layer 32 contains metal particles. The metal particles primarily include Cu particles primarily composed of Cu or a Cu alloy. The conductive metal may include, in addition to Cu particles, at least one metal particle selected from, for example, Ni, Ag, Pd, an Ag-Pd alloy, or Au. Hereinafter, the conductive metal will be referred to as metal particles or Cu particles 40. Furthermore, the conductive metal powder, which is the conductive metal before sintering, will be referred to as Cu powder 42. The base electrode layer 32 may also be multilayered. Note that FIG. 3 is an LT cross section of the base electrode layer 32, including the height direction x, i.e., a cross section in the thickness direction. However, the cross section of the base electrode layer 32 may be any cross section, such as a WT cross section or an LW cross section, as long as the cross section in the thickness direction of the base electrode layer 32 reveals the configuration of the base electrode layer 32.

[0036] The base electrode layer 32 is formed from a base electrode layer paste 31, which will be described later. The base electrode layer paste 31 according to this embodiment contains a resin, Cu powder 42 (conductive metal powder), glass powder 43 ( FIG. 5 ), and a solvent. The base electrode layer paste 31 is applied to the laminate 12 and then dried to form a dry film. The dried film is then degreased to form an unsintered base electrode layer 31a. The unsintered base electrode layer 31a then undergoes a metal sintering firing process to sinter the unsintered base electrode layer 31a, thereby forming the base electrode layer 32. The Cu powder 42 and the glass powder 43 are sintered to form Cu particles 40 (metal particles) and glass 45, respectively, through the metal sintering firing process. Although the resin contained in the unsintered base electrode layer 31a is degreased, at least a portion of the carbon (C) in the resin may remain in the unsintered base electrode layer 31a. Therefore, when the unsintered base electrode layer 31a is sintered in the metal sintering firing process, the remaining C may be fired in a state where it is in contact with the gas phase of the firing atmosphere. In this case, the C in contact with the gas phase of the firing atmosphere is converted into gas (CO2) during firing, which may cause defects such as glass lifting and blisters in the base electrode layer 32. The inventors have discovered that defects such as glass lifting and blisters can be suppressed when C is confined in the glass 45 ( FIG. 3 ) in the base electrode layer 32. Specifically, they have discovered that such defects can be suppressed by adjusting the C content in the glass 45 in the base electrode layer 32 to satisfy the following (Equation 1):

[0037] Glass floating is a phenomenon in which glass floats on the surface of the base electrode layer 32. Blisters are swelling of the base electrode layer 32 due to generated gas, for example.

[0038] FIG. 3 schematically illustrates a portion of the internal structure of the base electrode layer 32. The base electrode layer 32 is densified by sintering the unsintered base electrode layer 31a. In this embodiment, the base electrode layer 32 includes Cu particles 40, which are metal particles, and glass 45. The Cu particles 40 are Cu powder 42 in the base electrode layer paste 31 that has been densified by sintering. The glass 45 is glass powder 43 in the base electrode layer paste 31 that has been densified by sintering. More specifically, the base electrode layer 32 includes a plurality of Cu particles 40, and a plurality of glass particles 45 are interspersed among the plurality of Cu particles 40. Although not illustrated in FIG. 3, grain boundaries exist between the densified Cu particles 40.

[0039] As shown in FIG. 3 , the glass 45 includes a surface glass 45a and an inner glass 45b. At least a portion of the surface glass 45a faces the base electrode layer surface 33 of the base electrode layer 32. In this embodiment, the base electrode layer surface 33 is the surface on which the plating layer 34 is formed. The base electrode layer surface 33 is essentially the surface of the aggregate formed by the aggregation of a plurality of Cu particles 40 that faces the outside of the laminate 12. For example, at least a portion of the surface glass 45a is generally flush with the base electrode layer surface 33, or at least a portion of the surface glass 45a faces the base electrode layer surface 33 but is located more inward than the base electrode layer surface 33. Because the plating layer 34 is formed on the base electrode layer surface 33, it is preferable that the surface glass 45a does not protrude from the base electrode layer surface 33.

[0040] The inner glass 45b does not face the base electrode layer surface 33 but is located inside the base electrode layer 32, and is independent of the top glass 45a. In other words, the inner glass 45b is not continuous with the top glass 45a and is located inside the base electrode layer 32. As described above, C is introduced into the glass 45 in the base electrode layer 32. In this embodiment, the ratio of the C content to the element α content in the top glass 45a (C content / element α content) is defined as Rs. Furthermore, the ratio of the C content to the element α content in the inner glass 45b is defined as Ri. Rs and Ri are preferably comparable (the difference between Ri and Rs is small). Furthermore, the relationship between Rs and Ri is not particularly limited as long as they are comparable, but it is preferable that the following (Equation 1) is satisfied, for example: (Ri-Rs) / Ri≦29.5% (Formula 1) The lower limit of (Ri-Rs) / Ri is not particularly limited, but it is preferable that −29.5%≦(Ri-Rs) / Ri. Furthermore, the lower limit of (Ri-Rs) / Ri is not particularly limited, but it may be more preferably −8.9%≦(Ri-Rs) / Ri.

[0041] Furthermore, it is preferable that the inner glass 45b satisfy the following (Equation 2): That is, the ratio Rc of the C content to the content of elements in the third period or later in the periodic table in the inner glass 45b (C content / elements in the third period or later in the periodic table) is not particularly limited, but it is preferable that the following (Equation 2) is satisfied: Rc≧0.12 (Equation 2) Note that the upper limit of Rc is not particularly limited, but it is preferable that Rc≦0.23.

[0042] The elements in the third period or later in the periodic table in (Equation 2) are not particularly limited as long as they are elements in the third period or later, but may be, for example, Ba, Si, or Al, and do not include, for example, B and C in the second period of the periodic table. In this embodiment, the elements in the third period or later in the periodic table are detected by, for example, EDX (energy dispersive X-ray analysis). Note that it is difficult to detect B in the inner glass 45b using EDX.

[0043] Here, the positional relationship between the surface glass 45a and the internal glass 45b, which are the subject of comparison in (Equation 1) and the like, is as follows: For example, in the LT cross section shown in FIG. 3 (or any cross section in the thickness direction of the base electrode layer 32, such as a WT cross section or an LW cross section), the internal glass 45b is preferably located closest to the surface glass 45a on the internal side of the base electrode layer 32 (inner than the surface 33 of the base electrode layer). More specifically, for example, in the LT cross section (or any cross section in the thickness direction of the base electrode layer 32, such as a WT cross section or an LW cross section), the surface glass 45a and the internal glass 45b are preferably located closest to each other within the same field of view within a predetermined range. In this embodiment, the field area of ​​the same field of view is, for example, 0.07 μm 2 25 μm or more 2 The number of outer glass pieces 45a and the number of inner glass pieces 45b within the same field of view are not limited, and there may be a plurality of each.

[0044] The flatness of the base electrode layer 32 preferably satisfies the following (Formula 3): t1 is the minimum thickness of the base electrode layer 32 formed on the internal electrode layer 16 along the extension of the plate-like surface of the internal electrode layer 16. t2 is the maximum thickness of the base electrode layer 32 formed on the internal electrode layer 16 along the extension of the plate-like surface of the internal electrode layer 16. The cross section for determining the thicknesses t1 and t2 may be an LT cross section at any point in the width direction y of the multilayer ceramic capacitor 10. t1 and t2 are not particularly limited, but preferably satisfy the following (Formula 3): t2 / t1≦2.2 (Formula 3) The lower limit of t2 / t1 is not particularly limited, but it is preferable that 1.0≦t2 / t1.

[0045] The above t1 and t2 can also be obtained, for example, as shown in FIGS. 4A and 4B. In FIG. 4A, (a) is a partial cross-sectional view taken along line IVa-IVa in FIG. 1, and (b) is a partial cross-sectional view taken along line IVb-IVb in FIG. 1. In this embodiment, as shown by line IVa-IVa in FIG. 1, the LT surface of the multilayer ceramic capacitor 10 is polished along the width direction y to a portion where the internal electrode layer 16 is first exposed. A cross-sectional view of this LT surface is shown in FIG. 4A, and the thickness t1 of this first base electrode layer 32a is obtained. In the example of FIG. 4A, attention is focused on the internal electrode layer 16 located outermost in the height direction x among the multiple internal electrode layers 16 stacked in the height direction x in the LT cross section. The thickness of the first base electrode layer 32a (an example of a base electrode layer) formed along the extension of the outermost surface of the outermost internal electrode layer 16 in the length direction z relative to the first end surface 12e (an example of an end surface) of the laminate 12 is obtained as t1. Next, as shown by line IVb-IVb in FIG. 1 , the LT surface of the multilayer ceramic capacitor 10 is exposed and polished to 1 / 2 of the way in the width direction y. A cross-sectional view of this LT surface is shown in FIG. 4B, and the thickness t2 of this first base electrode layer 32a is obtained. In the example of FIG. 4B, the thickness t2 is obtained at a point 1 / 2 of the way in the height direction x.

[0046] The thickness t1 of the first and second base electrode layers 32a and 32b is preferably, for example, about 2 μm or more and 15 μm or less, and the thickness t2 of the first and second base electrode layers 32a and 32b is preferably, for example, about 5 μm or more and 50 μm or less.

[0047] The plating layer 34 includes a first plating layer 34a and a second plating layer 34b. The first plating layer 34a is disposed so as to cover the first base electrode layer 32a. The second plating layer 34b is disposed so as to cover the second base electrode layer 32b. The first plating layer 34a and the second plating layer 34b each include at least one selected from the group consisting of Cu, Ni, Sn, Ag, Pd, an Ag—Pd alloy, and Au.

[0048] The first plating layer 34 a and the second plating layer 34 b may be formed of multiple layers. In this case, the plating layer 34 preferably has a two-layer structure including a lower plating layer formed by Ni plating on the base electrode layer 32 and an upper plating layer formed by Sn plating on the lower plating layer.

[0049] That is, the first plating layer 34a has a first lower plating layer and a first upper plating layer located on the surface of the first lower plating layer, and the second plating layer 34b has a second lower plating layer and a second upper plating layer located on the surface of the second lower plating layer.

[0050] The lower plating layer made of Ni is used to prevent the base electrode layer 32 from being eroded by solder when mounting the multilayer ceramic capacitor 10 on a substrate or the like. The upper plating layer made of Sn is used to improve the wettability of solder when mounting the multilayer ceramic capacitor 10 on a substrate or the like, thereby facilitating mounting. The thickness of each of the upper plating layer and the lower plating layer is preferably, for example, 2.0 μm or more and 7.0 μm or less.

[0051] 2. Method for Manufacturing the Multilayer Ceramic Capacitor Next, a method for manufacturing the multilayer ceramic capacitor 10 will be described.

[0052] (Step 1) First, a dielectric sheet for the ceramic layer and a conductive paste for the internal electrode layer are prepared. The dielectric sheet for the ceramic layer is formed from a dielectric slurry containing, for example, but not limited to, BaTiO3 as a main component. The conductive paste for the internal electrode layer is formed from, for example, but not limited to, Ni as a main component. The dielectric sheet and the conductive paste for the internal electrode layer contain a binder and a solvent. The binder and the solvent are composed of a resin component.

[0053] (Step 2) Then, a conductive paste for the internal electrode layers is printed in a predetermined pattern on the dielectric sheet by, for example, screen printing, gravure printing, etc. In this way, a dielectric sheet on which the pattern of the first internal electrode layer is formed, and a dielectric sheet on which the pattern of the second internal electrode layer is formed are prepared.

[0054] Furthermore, with regard to the dielectric sheets, dielectric sheets for outer layer portions on which no patterns of internal electrode layers are printed are also prepared.

[0055] A predetermined number of dielectric sheets for the outer layer portion, on which the pattern of the internal electrode layer is not printed, are laminated. A dielectric sheet on which the pattern of the first internal electrode layer is printed and a dielectric sheet on which the pattern of the second internal electrode layer is printed are laminated in this order on top of the dielectric sheets, to form a portion that will become the effective layer portion. A predetermined number of dielectric sheets for the outer layer portion, on which the pattern of the internal electrode layer is not printed, are laminated on top of this portion that will become the effective layer portion. In this way, a laminate sheet having an effective layer portion and an outer layer portion is formed.

[0056] (Step 3) Next, the laminated sheet is pressed in the lamination direction by means of a hydrostatic press or the like to produce a laminated block.

[0057] (Step 4) The laminated block is then cut to a predetermined size to cut out laminated chips.

[0058] (Step 5) Next, the resin component in the stacked chip is removed. The degreasing temperature for removing the resin component in step 5 is, for example, higher than 250°C and not higher than 800°C.

[0059] (Step 6) Next, the laminated chip is fired to produce the laminate 12. The firing temperature for the laminated chip depends on the materials of the ceramic layers and internal electrode layers, which are dielectrics, but is preferably higher than 1000°C and lower than 1300°C, for example. This firing fires the patterns of the internal electrode layers and the dielectric sheets, turning them into the internal electrode layers 16 and ceramic layers 14.

[0060] (Step 7) Next, the base electrode layer paste 31 is applied to the first and second end faces 12e, 12f of the laminate 12, dried, and fired, thereby forming the base electrode layer 32 of the external electrode 30.

[0061] Step 7 will be described in more detail. Figures 5(a) to 5(c) are schematic diagrams showing the process of introducing the C remaining after degreasing the resin into the glass. Figures 6(a) to 6(d) are diagrams for explaining the process of applying the paste for the base electrode layer to the laminate in this embodiment.

[0062] (a) Preparation of Base Electrode Layer Paste First, the base electrode layer paste 31 according to this embodiment will be described. The base electrode layer paste 31 is a paste for forming the base electrode layer 32. The base electrode layer paste 31 according to this embodiment contains a resin, a conductive metal powder, glass powder 43 (FIG. 5(a)), and a solvent. In this embodiment, Cu powder 42 (FIG. 5(a)) is used as the conductive metal powder. The resin is an acrylic resin and an ethyl cellulose resin, at least a portion of which are copolymerized.

[0063] The acrylic resin is, for example, at least one of isobutyl methacrylate, methyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, n-butyl methacrylate, and 2-ethylhexyl methacrylate.

[0064] The ethyl cellulose resin is primarily a resin with a six-membered ring structure, such as ethyl cellulose. In the above, an ethyl cellulose resin at least partially copolymerized with an acrylic resin is cited as an example of the resin contained in the base electrode layer paste 31. However, other than the ethyl cellulose resin, examples of the resin at least partially copolymerized with an acrylic resin include at least one cellulose resin selected from the group consisting of methyl cellulose, hydroxypropyl cellulose, trityl cellulose, acetyl cellulose, carboxymethyl cellulose, and nitrocellulose. Below, a base electrode layer paste 31 using primarily an ethyl cellulose resin will be described. However, cellulose resins other than the ethyl cellulose resin, such as those mentioned above, also have the same functions as the ethyl cellulose resin.

[0065] The Cu powder 42 is a powder made of at least one of Cu and a Cu alloy. The particle size of the Cu powder 42 is preferably, for example, 0.1 μm or more and 8.0 μm or less in order to suppress the void ratio in the base electrode layer 32 and ensure strength.

[0066] The glass powder 43 is primarily composed of element α and contains at least Si. The element α is Ba or Sr. The glass powder 43 may additionally contain at least one element selected from the group consisting of B, Zn, Ca, Mg, Al, Li, Bi, Na, K, Ti, Zr, Cu, Mn, Co, Ni, Fe, and V. Examples of the glass powder 43 include Ba-Si-B-based glass powder, Ba-Si-B-Zn-based glass powder, Sr-Si-B-based glass powder, and Ba-Si-B-Zn-Ca-Al-based glass powder. The glass powder 43 may also contain a borosilicate glass composition. The borosilicate glass composition is a glass composition containing B oxide and Si oxide as network-forming oxides and alkali metal element oxides and alkaline earth metal element oxides as modifying oxides.

[0067] The solvent may include, for example, at least one of terpineol, dihydroterpineol, dihydroterpinyl acetate, propylene glycol phenyl ether, benzyl alcohol, texanol, and butyl carbitol acetate. The solvent species can be analyzed by measuring the evolved gas using gas chromatography-mass spectrometry. Gas chromatography-mass spectrometry can be performed using, for example, a mass spectrometer 7890A / 5975C (heated to 500°C) manufactured by Agilent Technologies, Inc.

[0068] In addition, the base electrode layer paste 31 may contain various additives such as a dispersant, a plasticizer, an anti-settling agent, and a thixotropic agent.

[0069] The base electrode layer paste 31 is produced by weighing and mixing at least a partially copolymerized acrylic resin and ethyl cellulose resin with Cu powder 42, glass powder 43, and a solvent to a predetermined mixing ratio, and then dispersing and kneading the mixture using a triple-roll mill or the like. In the base electrode layer paste 31, for example, the resin is 3.5 wt% to 6.9 wt%, the Cu powder 42 is 42.3 wt% to 59.8 wt%, the glass powder 43 is 3.4 wt% to 8.7 wt%, and the solvent is 30.9 wt% to 44.8 wt%, totaling 100 wt%. The weight ratio of the acrylic resin to the ethyl cellulose resin is preferably 3:7 to 8:2, for example, from the viewpoint of improving the strength of the dried film. The ratio of the Cu powder 42 and the glass powder 43 to the non-volatile components other than the solvent is preferably 50 vol% to 70 vol%.

[0070] When the base electrode layer 32 is formed using the base electrode layer paste 31 containing the Cu powder 42, it is preferable to perform degreasing and firing under a low oxygen partial pressure in order to suppress the occurrence of blister defects and to suppress the oxidation of the Cu powder 42. From this viewpoint, it is preferable that the base electrode layer paste 31 contains a large amount of acrylic resin, which is a resin that thermally decomposes even in a small amount of oxygen.

[0071] As described above, the acrylic resin and the ethyl cellulose resin are at least partially copolymerized. For example, the OH group of the ethyl cellulose resin is substituted with a vinyl group, and the ethyl cellulose resin and the acrylic resin are bonded via the substituted vinyl group.

[0072] However, if a base electrode layer paste containing only an ethyl cellulose-based resin and an acrylic-based resin without copolymerization is used, the dried film will be brittle. Therefore, in a multilayer ceramic capacitor coated with such a base electrode layer paste, the dried film of the base electrode layer paste may chip or peel during the transport process. This is thought to be due to the following reasons.

[0073] The base electrode layer paste 31 according to the present embodiment contains a resin in which an acrylic resin and an ethyl cellulose resin are at least partially copolymerized. The dried film obtained by applying the base electrode layer paste 31 to the laminate 12 and drying it is resistant to phase separation. Therefore, the dried film has flexibility, or in other words, toughness, derived from the acrylic resin and rigidity derived from the ethyl cellulose resin, and has sufficient strength.

[0074] In contrast, in the case of a base electrode layer paste containing a non-copolymerized acrylic resin and an ethyl cellulose resin, phase separation between the acrylic resin and the ethyl cellulose resin is promoted during the kneading process with Cu powder during the manufacturing process. As a result, glass powder 43 segregates in the base electrode layer paste. When an external force is applied to a dried film obtained by applying this base electrode layer paste to laminate 12, cracks tend to develop from brittle areas such as the interface between the glass segregation portion and Cu powder 42, which is thought to cause chipping or peeling.

[0075] (b) Method for Forming Base Electrode Layer Next, a method for forming the base electrode layer 32 using the base electrode layer paste 31 according to the present embodiment will be described. In this embodiment, first, as shown in FIG. 6 , in a base electrode layer paste application step, the base electrode layer paste 31 is applied to the laminate 12. Then, in a base electrode layer paste drying step, the base electrode layer paste 31 applied to the laminate 12 is dried to form a dry film. Then, in a dried film degreasing step, the resin component in the dried film is degreased to form an unsintered base electrode layer 31a. Then, as shown in FIG. 5 , a C introduction step into the glass is performed. Then, a metal sintering firing step is performed. The base electrode layer paste application step, the base electrode layer paste drying step, the dried film degreasing step, the C introduction step into the glass, and the metal sintering firing step will be described below.

[0076] (b1) Base Electrode Layer Paste Application Step In the base electrode layer paste application step, as shown in FIG. 6( a), a region of the laminate 12 where the base electrode layer 32 is to be formed is immersed in the base electrode layer paste 31, and then the laminate 12 is lifted up. The region where the base electrode layer 32 is to be formed is, for example, both end faces (first end face 12 e) and second end face 12 f) of the laminate 12. When the laminate 12 is lifted up, Marangoni convection occurs between the center and the end of the base electrode layer paste 31 attached to the laminate 12 due to temperature differences and solute concentration differences between the center and the end, as shown by the arrows in FIG. 6( b). The solutes are Cu powder 42, glass powder 43, and resin contained in the base electrode layer paste 31.

[0077] Since the amount of base electrode layer paste 31 applied at the edges is smaller than that at the center, drying proceeds more quickly at the edges. Therefore, the resin content in the base electrode layer paste 31 is higher at the edges than at the center, making the paste energetically unstable. As a result, as shown in FIG. 6C, an outward flow occurs in which the base electrode layer paste 31 flows from the center to the edges. This outward flow occurs while the resin concentration at the edges is higher than that at the center. It is believed that as drying proceeds, the number of interfaces between the solute and the solvent increases, making the paste energetically unstable and strengthening the outward flow.

[0078] Here, the ethyl cellulose-based resin has rigidity and high heat storage capacity, which prevents the base electrode layer paste 31 from solidifying during the drying process of the base electrode layer paste and promotes outward flow. The strong outward flow causes the base electrode layer paste 31 to flow from the center to the edges. This prevents the base electrode layer paste 31 from bulging outward in the center. As shown in FIG. 6(d) , the base electrode layer paste 31 is applied flat on the edge surface, and a portion of it dries. In this way, the ethyl cellulose-based resin contributes to the flatness of the base electrode layer paste 31 and, ultimately, the flatness of the base electrode layer 32. Using at least one of methyl cellulose, hydroxypropyl cellulose, trityl cellulose, acetyl cellulose, carboxymethyl cellulose, and nitrocellulose in the base electrode layer paste 31, other than the ethyl cellulose-based resin, can also contribute to the flatness of the base electrode layer 32 in the same manner as described above.

[0079] (b2) Drying Process of Base Electrode Layer Paste Next, a drying process is performed to volatilize the solvent in the base electrode layer paste 31 applied to the laminate 12. The drying process is performed, for example, at a temperature of 90°C or higher and 110°C or lower, for example, at a temperature of 100°C. This causes the base electrode layer paste 31 to dry. The film formed by drying the base electrode layer paste 31 is called a dried film. The dried film mainly contains resin, Cu powder 42, and glass powder 43.

[0080] (b3) Degreasing step of dried film Next, a degreasing step is performed to remove the resin from the resin component in the dried film. As a result, the dried film becomes an unsintered base electrode layer 31a. The degreasing step is performed at a temperature of 120°C or higher and 500°C or lower, for example, 400°C.

[0081] (b4) Process for Incorporating Carbon into Glass Even after the degreasing process for the dried film and before the firing process for metal sintering, at least a portion of the carbon (C) in the resin may remain in the unsintered base electrode layer 31a. Therefore, a process for incorporating the remaining carbon (C) into the glass 45 is then performed. Here, the acrylic resin imparts flexibility and toughness to the dried film. Furthermore, the acrylic resin is easily thermally decomposed, making it difficult for carbon to remain during degreasing of the resin components. Furthermore, the ethyl cellulose resin has rigidity and imparts hardness to the dried film. Furthermore, the ethyl cellulose resin contributes to ensuring the flatness of the dried film at the end surfaces of the laminate. On the other hand, unlike the acrylic resin, the ethyl cellulose resin, which primarily has a six-membered ring structure, is less susceptible to thermal decomposition and therefore tends to leave carbon remaining during degreasing of the resin components. Therefore, in the process for incorporating carbon into the glass, the carbon remaining after degreasing of the resin components is incorporated into the glass 45. This will be explained below with reference to FIG.

[0082] FIG. 5A shows the state of the green base electrode layer 31a after the dry film degreasing process. As shown in FIG. 5A, the green base electrode layer 31a contains Cu powder 42, glass powder 43, and residual carbon (C). In the green base electrode layer 31a shown in FIG. 5A, the Cu powders 42 and the glass powders 43 are not completely sintered, but rather are mixed together. Furthermore, gaps exist between the Cu powders 42, between the glass powders 43, and between the Cu powders 42 and the glass powders 43. In this state, the residual carbon, even after degreasing of the resin component, is present on the surface 31b of the green base electrode layer 31a and further inside than the surface 31b, for example, on the surface of the Cu powder 42. The surface 31b is mainly formed by the surface of the outermost Cu powder 42.

[0083] Here, the glass powder 43 includes a surface glass powder 43a and an inner glass powder 43b. The surface glass powder 43a is sintered to form a surface glass 45a in a firing process for metal sintering. As shown in FIG. 5(a), the surface glass powder 43a is located near the surface 31b of the unsintered base electrode layer 31a after the degreasing process for the dried film. More specifically, the surface glass powder 43a has a portion facing the surface 31b of the unsintered base electrode layer 31a, or a portion facing the surface of the fired product during the firing process for metal sintering. Meanwhile, the inner glass powder 43b is sintered to form an inner glass 45b in a firing process for metal sintering. As shown in FIG. 5(a), the inner glass powder 43b does not face the surface 31b of the unsintered base electrode layer 31a after the degreasing process, but is located deeper than the surface 31b and is independent of the surface glass powder 43a. That is, the inner glass powder 43b is not continuous with the surface glass powder 43a and is located inside the surface 31b.

[0084] As shown in FIG. 5B, the unsintered base electrode layer 31a shown in FIG. 5A is fired for a predetermined time at a temperature capable of softening at least a portion of the glass powder 43 in an atmosphere that does not oxidize the Cu powder 42 (conductive metal powder). The atmosphere that does not oxidize the Cu powder 42 (conductive metal powder) varies depending on the firing target, but may include, for example, a reducing atmosphere or an oxidizing atmosphere. The temperature capable of softening at least a portion of the glass powder is, for example, within a predetermined temperature range relative to the glass softening point. The glass softening point is not limited to, but may be, for example, 610°C or higher and 650°C or lower. The predetermined temperature range relative to the glass softening point is not limited to, but may be, for example, ±15°C. The glass softening point is preferably equal to or higher than the shrinkage onset temperature of the Cu powder 42. The shrinkage onset temperature of the Cu powder 42 may be, for example, 280°C or higher and 550°C or lower. The atmosphere in which the Cu powder 42 (conductive metal powder) does not oxidize varies depending on the object to be fired, but includes, for example, a reducing atmosphere and an oxidizing atmosphere. Examples of the reducing atmosphere include a nitrogen atmosphere and an atmosphere containing hydrogen and water. The predetermined time is, for example, the time required for the remaining C to be incorporated into the glass powder 43 so as not to induce defects in the base electrode layer 32 during the firing process for metal sintering.

[0085] This firing softens at least a portion of the glass powder 43 and incorporates the remaining C into the softened glass powder 43. Specifically, as shown in FIG. 5B, the glass powder 43 is softened to form softened glass 44. The softened glass 44 is at least partially softened and has increased fluidity compared to the glass powder 43. In other words, the softened glass 44 can be said to be at least partially molten. The surface glass powder 43a becomes surface-softened glass 44a, and the internal glass powder 43b becomes internal-softened glass 44b. At this time, at least a portion of the Cu powder 42 can be sintered and densified to become partially sintered Cu powder 42. Furthermore, the surface-softened glass 44a and the internal-softened glass 44b can be fluidized to fill the spaces between the partially sintered Cu powder 42.

[0086] 5C, at least a portion of the C in contact with the surface-softened glass 44a and the internally softened glass 44b is incorporated into the surface-softened glass 44a and the internally softened glass 44b. In particular, in the example of FIG. 5C, the surface-softened glass 44a and the internally softened glass 44b are fluidized and fill the gaps between the Cu powder 42 in the middle of sintering, so that the C remaining on the surface of the Cu powder 42 in the middle of sintering is likely to come into contact with the surface-softened glass 44a and the internally softened glass 44b. Therefore, at least a portion of the remaining C is likely to be incorporated into the surface-softened glass 44a and the internally softened glass 44b.

[0087] After a predetermined period of time has passed since the treatment for incorporating the remaining C into the surface-softened glass 44a and the internal-softened glass 44b, the temperature is lowered to complete the process of incorporating C into the glass. Note that the temperature lowering treatment may be omitted.

[0088] (b4) Firing Step for Metal Sintering Next, after the step of introducing C into the glass shown in FIG. 5 , a firing step for metal sintering is performed. That is, the laminate 12 having the green base electrode layer 31a formed thereon after the step of introducing C into the glass is fired in a predetermined firing atmosphere. This forms the base electrode layer 32 shown in FIG. 3 . The firing temperature in the firing step for metal sintering is preferably, for example, 700°C or higher and 900°C or lower. The Cu powder 42 ((b) and (c) in FIG. 5 ) in the green base electrode layer 31a during sintering is sintered to form Cu particles 40 ( FIG. 3 ). The surface softened glass 44a and the internal softened glass 44b ((b) and (c) in FIG. 5 ) in the green base electrode layer 31a are sintered to form the surface glass 45a and the internal glass 45b ( FIG. 3 ), respectively.

[0089] (Step 8) Next, the plating layer 34 is formed on the base electrode layer 32. The plating layer 34 is formed, for example, by laminating a Ni plating layer and a Sn plating layer in this order on the base electrode layer 32.

[0090] The multilayer ceramic capacitor 10 is manufactured using the above-described manufacturing method. The manufacturing method for the multilayer ceramic capacitor 10 is particularly characterized by step 7. This manufacturing method includes the steps of preparing a base electrode layer paste, applying the base electrode layer paste, drying the base electrode layer paste, degreasing the dried film, introducing C into the glass, and firing for metal sintering, and can be described as follows: First, a base electrode layer paste 31 is prepared, which includes at least a partially copolymerized acrylic resin and an ethyl cellulose resin, Cu powder 42, glass powder 43, and a solvent (preparing the base electrode layer paste). Next, the base electrode layer paste 31 is applied to the end surface of the laminate 12 (applying the base electrode layer paste). Next, the base electrode layer paste 31 applied to the laminate 12 is dried to form a dry film (drying the base electrode layer paste). Next, the resin component in the dried film is degreased to form an unsintered base electrode layer 31a (degreasing the dried film). The glass powder 43 in the unsintered base electrode layer 31a includes a surface glass powder 43a and an inner glass powder 43b. The surface glass powder 43a has a portion facing the surface 31b of the unsintered base electrode layer 31a, or a portion facing the surface of the fired product during the metal sintering firing process. The inner glass powder 43b does not face the surface 31b of the unsintered base electrode layer 31a, but is located deeper than the surface 31b of the unsintered base electrode layer 31a, and is independent of the surface glass powder 43a. Next, the unsintered base electrode layer 31a is fired for a predetermined time at a temperature that softens at least a portion of the glass powder 43 in an atmosphere that does not oxidize the Cu powder 42 (conductive metal powder). The surface glass powder 43a becomes surface-softened glass 44a, and the inner glass powder 43b becomes inner-softened glass 44b. The process is performed so that at least a portion of the remaining C is incorporated into the surface-softened glass 44 a and the internal-softened glass 44 b (a process for incorporating C into glass). Next, the laminate 12 having the unsintered base electrode layer 31 a that has been subjected to the process for incorporating C into glass is fired in a predetermined firing atmosphere to form the base electrode layer 32 (a firing process for metal sintering).

[0091] 3. Effects (1) Effects Based on Formula 1 The multilayer ceramic capacitor 10 configured as described above satisfies Formula 1 above, and therefore can suppress defects such as glass lift and blisters in the base electrode layer 32. To explain the effects of the multilayer ceramic capacitor 10 configured as described above, defects such as glass lift and blisters in conventional multilayer ceramic capacitors will first be described.

[0092] Fig. 7 is a schematic diagram showing the internal structure of a base electrode layer of a conventional multilayer ceramic capacitor. Fig. 8 (a) and (b) are schematic diagrams showing steps of forming a base electrode layer through a firing step for metal sintering after applying a paste for a base electrode layer, drying and degreasing, in a conventional method for manufacturing a multilayer ceramic capacitor.

[0093] As shown in FIG. 7 , the base electrode layer 52 of the conventional multilayer ceramic capacitor includes Cu particles 40 and glass 45. The glass 45 includes a surface glass 45a and an inner glass 45b. The surface glass 45a faces a base electrode layer surface 53 of the base electrode layer 52. The base electrode layer surface 53 is the surface on which the plating layer 34 is formed. The inner glass 45b does not face the base electrode layer surface 53 but is located inside the base electrode layer 52 and is independent of the surface glass 45a. Unlike the base electrode layer 32 according to the present embodiment, the base electrode layer 52 of the conventional multilayer ceramic capacitor does not satisfy the above-described formula 1. That is, in the base electrode layer 52, the ratio Rs of the C content to the element α content in the surface glass 45a and the ratio Ri of the C content to the element α content in the inner glass 45b do not satisfy the above-described formula 1. This is thought to mean that the C content in the surface glass 45a of the base electrode layer 52 is relatively low. Therefore, it is thought that the firing process for metal sintering was performed in a state where a relatively large amount of C remained in the unsintered base electrode layer 31a in the portions other than the surface glass 45a. In other words, it is thought that the firing of the laminate 12 formed with the unsintered base electrode layer 31a was performed in a state where a relatively large amount of C was in contact with the gas phase of the firing atmosphere in the firing process for metal sintering. As a result, it is thought that the relatively large amount of C was rapidly gasified during firing in contact with the gas phase of the firing atmosphere, resulting in the glass lift 46, blisters, etc., in the base electrode layer 52 as shown in FIG. 7. In particular, it is thought that the relatively large amount of C was present deeper than the surface 31b of the unsintered base electrode layer 31a, on the Cu powder 42 near the surface 31b, and in contact with the gas phase of the firing atmosphere during firing of the laminate 12. It is believed that the combustion gas of this carbon pushed aside the surface glass 45a and was released to the outside, causing the glass lift 46, blisters, etc. It is also believed that the carbon that was present on the surface 31b of the unsintered base electrode layer 31a was released directly from the surface 31b to the outside by firing.

[0094] The formation of the base electrode layer 52 of the conventional multilayer ceramic capacitor described here will now be further examined. The same base electrode layer paste 31 as that of the present embodiment is used to form the base electrode layer 52. As described above, the base electrode layer paste 31 of the present embodiment contains at least a partially copolymerized acrylic resin and ethyl cellulose resin (resin components), Cu powder 42 ( FIG. 8( a)), glass powder 43 ( FIG. 8( a)), and a solvent. This base electrode layer paste 31 is applied to the laminate 12 in the same manner as in FIG. 6 of the above embodiment. Thereafter, as in the above embodiment, in the base electrode layer paste drying step, the base electrode layer paste 31 is dried to form a dried film. Then, in the dried film degreasing step, the resin components in the dried film are degreased to form an unsintered base electrode layer 31a. FIG. 8( a) shows the state of the unsintered base electrode layer 31a after the dried film degreasing step. The state of the unsintered base electrode layer 31a in Fig. 8(a) is the same as the state of the unsintered base electrode layer 31a in Fig. 5(a). That is, in the unsintered base electrode layer 31a in Fig. 8(a), the plurality of Cu powders 42 and the plurality of glass powders 43 are not completely sintered, but are in a state in which the plurality of Cu powders 42 and the plurality of glass powders 43 are mixed together. Furthermore, gaps exist between the plurality of Cu powders 42, between the plurality of glass powders 43, and between the plurality of Cu powders 42 and the plurality of glass powders 43. In this state, the C remaining even after degreasing of the resin component is present on the surface 31b of the unsintered base electrode layer 31a and further inside than the surface 31b, for example, on the surface of the Cu powder 42.

[0095] Next, the laminate 12 with the green base electrode layer 31a formed as shown in FIG. 8A is introduced into the metal sintering firing process of the above embodiment and fired. At this time, as shown in FIG. 8B, the green base electrode layer 31a is fired in a state where the remaining C is exposed to the gas phase of the firing atmosphere. In this case, the C in contact with the gas phase of the firing atmosphere is converted into gas (CO2) by firing. This gas can then cause glass floats 46, blisters, etc. in the base electrode layer 52 as shown in FIG.

[0096] The conventional manufacturing method of a multilayer ceramic capacitor shown in FIGS. 8(a) and 8(b) and FIG. 7 does not include a process of firing for a predetermined time at a temperature capable of softening at least a portion of the glass powder 43 (a process of incorporating C into the glass), as shown in FIG. 5(b). Furthermore, it does not include a process of incorporating the remaining C into the softened glass 44 (a process of incorporating C into the glass), as shown in FIG. 5(c). Therefore, during the process of transforming the state shown in FIG. 8(a) through FIG. 8(b) to the base electrode layer 52 shown in FIG. 7, the temperature of the unsintered base electrode layer 31a is rapidly raised to the firing temperature in the firing process for metal sintering. Therefore, although the glass powder 43 softens to form the softened glass 44 (surface softened glass 44a and internal softened glass 44b), the C exposed to the gas phase of the firing atmosphere may gasify without being incorporated into the softened glass 44. This can result in defects such as glass lift 46 and blisters, as shown in FIG. 7.

[0097] Further explanation follows. For example, as shown in FIG. 8B , carbon is present on Cu powder 42 near surface 31b of unsintered base electrode layer 31a, below surface 31b, and in contact with the gas phase of the firing atmosphere. This carbon may be converted into gas (CO2) during firing without being incorporated into surface-softened glass 44a. This gas is then expelled, pushing surface-softened glass 44a outward. That is, as shown in the enlarged portion of FIG. 8B , carbon remains on the surface of Cu powder 42 near the bottom of surface-softened glass 44a without being incorporated into surface-softened glass 44a. In FIG. 8B , the process of introducing carbon into glass is absent, and therefore softening of softened glass 44 is insufficient. Therefore, gaps are likely to form between surface-softened glass 44a and internal-softened glass 44b and Cu powder 42. 5(b) and 5(c), the gaps between the surface-softened glass 44a and the internal-softened glass 44b and the Cu powder 42 are not filled with the surface-softened glass 44a and the internal-softened glass 44b. Therefore, the remaining C is likely to adhere to the surfaces of the Cu powder 42 facing the gaps. This remaining C is gasified by combustion and, as shown in the enlarged portion of FIG. 8(b), is released to the outside while pushing the surface-softened glass 44a outward as it passes through the inside of the surface-softened glass 44a. This can cause defects such as glass lift 46 and blisters as shown in FIG. 7 in the base electrode layer 52 after firing the unsintered base electrode layer 31a.

[0098] Such defects are more likely to occur as the amount of C remaining in the unsintered base electrode layer 31a increases. In other words, the more C present on the Cu powder 42 in a state exposed to the gas phase of the firing atmosphere, the more rapid gasification of C occurs, making defects more likely to occur. In particular, it is thought that the defects are more likely to occur when the remaining C is present in the unsintered base electrode layer 31a closer to the surface 31b than when the remaining C is present on the surface 31b of the unsintered base electrode layer 31a.

[0099] 8(b), C and the like present on Cu powder 42 in a portion further from surface 31b of unsintered base electrode layer 31a has little opportunity to come into contact with the gas phase of the firing atmosphere. Therefore, it is thought that the C located further from surface 31b of unsintered base electrode layer 31a is more likely to be incorporated into internal softened glass 44b and is less likely to cause the above-mentioned defects.

[0100] According to this embodiment, the above formula (1) is satisfied, and the difference between Ri and Rs is small. In other words, the difference between the C content incorporated in the surface glass layer 45a and the C content incorporated in the inner glass layer 45b is small. In other words, the surface glass layer 45a incorporates C to the same extent as the inner glass layer 45b. Therefore, when the unsintered base electrode layer 31a is subjected to a firing process for metal sintering, the amount of C in contact with the gas phase of the firing atmosphere can be reduced. This prevents rapid gasification of C during firing of the unsintered base electrode layer 31a, thereby providing a multilayer ceramic capacitor 10 that can suppress defects such as glass lift and blisters in the base electrode layer 32. In particular, it is preferable that C, etc., present on the Cu powder 42 near the surface 31b inside the unsintered base electrode layer 31a and in contact with the gas phase of the firing atmosphere, be incorporated into the surface glass layer 45a. In this way, when C and other substances deeper than the surface 31b are absorbed into the surface glass 45a, gasification of C and other substances can be suppressed, and defects such as glass floating and blisters in the surface glass 45a due to the gas being released to the outside can be suppressed.

[0101] Furthermore, according to this embodiment, the C remaining in the unsintered base electrode layer 31a can be trapped in the glass 45, which can prevent the C remaining in the unsintered base electrode layer 31a from inhibiting the sintering of the Cu powder 42, etc.

[0102] Furthermore, according to this embodiment, defects such as glass lift and blisters can be suppressed, thereby improving the plating adhesion of the plating layer 34 on the base electrode layer 32. This suppresses the intrusion of the plating solution into the base electrode layer 32 and the deterioration of solderability due to peeling of the plating layer 34. It is also possible to suppress the intrusion of moisture and the like into the laminate 12 after firing from defective areas such as glass lift and blisters. Furthermore, suppressing these defects also enables further planarization of the base electrode layer 32. This also makes it possible to reduce the size of the multilayer ceramic capacitor 10 and improve its moisture resistance reliability.

[0103] In this embodiment, an ethyl cellulose-based resin is contained in the base electrode layer paste 31 from the viewpoints of the flatness of the base electrode layer 32, the strength of the dried film, etc. Although it is generally desirable to remove C when degreasing the dried film after drying the base electrode layer paste 31, ethyl cellulose-based resins are difficult to thermally decompose and tend to leave residual C. Therefore, when using a resin that tends to leave residual C, the multilayer ceramic capacitor 10 and its manufacturing method in which C is enclosed in the glass 45 of the base electrode layer 32 under the condition that satisfies (Equation 1), as in this embodiment, are useful.

[0104] (2) Effect of Equation 2 According to the above configuration, since Equation 2 is satisfied, a certain amount of C remains in the inner glass 45b of the base electrode layer 32. This indicates that the base electrode layer paste 31 contains an ethyl cellulose-based resin, which tends to retain C even during the degreasing process when forming the base electrode layer 32. Ethyl cellulose-based resins tend to be rigid. This can increase the dry film strength after drying the base electrode layer paste 31 applied to the laminate 12, thereby increasing the strength of the base electrode layer 32. Furthermore, the ethyl cellulose-based resin can improve the flatness of the base electrode layer 32. Here, the reason we focused on the C content in the inner glass 45b is that C in and near the inner glass 45b is less likely to be exposed to the firing atmosphere than C in and near the surface glass 45a, making it easier to confirm the presence of a resin with the aforementioned characteristics. In this embodiment, ethyl cellulose-based resin is used as an example of such a resin.

[0105] (3) Effects of Equation 3 According to the above configuration, since the above (Equation 3) is satisfied, it is possible to form a base electrode layer 32 with improved flatness. Therefore, the multilayer ceramic capacitor 10 having the base electrode layer 32 can be made thinner and more compact. Furthermore, when compared at the same size, the base electrode layer 32 can be made thinner and the internal elements can be made larger, which makes it possible to increase capacitance.

[0106] (4) Effects of the Proximity of the Inner Glass and the Surface Glass According to the above configuration, in (Equation 1) and the like, the inner glass 45b is located closest to the surface glass 45a on the inner side of the base electrode layer 32. Specifically, the inner glass 45b and the surface glass 45a are located closest to each other within a predetermined field of view in a cross section of the base electrode layer 32 in the thickness direction. In other words, because the inner glass 45b and the surface glass 45a are located close to each other, the firing conditions for firing the unsintered base electrode layer 31a formed in the laminate 12 can be made similar. This eliminates differences in the C content due to differences in firing conditions. Therefore, by comparing the C content of the inner glass 45b and the surface glass 45a fired under similar firing conditions, the C content can be more accurately compared in (Equation 1) above. Firing conditions include temperature, firing atmosphere, hot air volume and flow, etc. Furthermore, when the multilayer ceramic capacitor 10 is mass-produced, multiple laminates 12 are fired simultaneously, so the firing conditions may also include the orientation of the multiple laminates 12, the contact state between the multiple laminates 12, etc.

[0107] In order to accurately compare the C content between the surface glass 45a and the internal glass 45b, in the above embodiment, the C content is compared between the surface glass 45a and the internal glass 45b that exist within the same field of view of a specified area.

[0108] 4. Experimental Examples Next, experimental examples will be described. As experimental examples, Example 1 and Comparative Examples 1 and 2 were carried out.

[0109] (1) Example 1 Example 1 according to this embodiment will be described below.

[0110] A. Sample Preparation Copolymerized acrylic resin and ethyl cellulose resin, Cu powder, glass powder, and a solvent were prepared. The Cu powder was spherical and had an average particle size of 0.3 μm. The glass powder was Ba-Si-B glass powder. Terpineol was used as the solvent. The copolymerized acrylic resin and ethyl cellulose resin, Cu powder, glass powder, and solvent were blended and mixed in a planetary mixer, and then dispersed and kneaded in a three-roll mill to prepare a sample of the base electrode layer paste of Example 1.

[0111] Next, a laminate was prepared in which internal electrode layers mainly composed of Ni and ceramic layers made of BaTiO were stacked. The laminate had a length L dimension of 0.6 mm in the length direction z, a width W dimension of 0.3 mm in the width direction y, and a height T dimension of 0.3 mm in the height direction x.

[0112] The end surface of the laminate was immersed in the above-mentioned paste for the base electrode layer, and then pulled up, thereby applying the paste for the base electrode layer to the end surface of the laminate (corresponding to the application process of the paste for the base electrode layer in this embodiment).

[0113] Next, the laminate coated with the paste for the base electrode layer was left to dry for 10 minutes in an oven heated to approximately 100°C, thereby forming a dry film (corresponding to the drying process for the paste for the base electrode layer in this embodiment).

[0114] Next, the laminate with the post-resin dry film formed thereon was heated in a nitrogen atmosphere to 630°C, which is within the range of the glass softening point ±15°C, and then left to stand for 8 minutes. This degreasing of the resin component in the dry film formed an unsintered base electrode layer, and also allowed the carbon remaining in the unsintered base electrode layer to be incorporated into the surface softened glass and the internal softened glass. The temperature was then lowered (corresponding to the process of degreasing the dry film and the process of incorporating carbon into the glass according to this embodiment). In Example 1, the process of degreasing the dry film and the process of incorporating carbon into the glass were carried out simultaneously.

[0115] Next, the laminate on which the dry film was formed was fired at 700° C. in a nitrogen atmosphere (corresponding to the firing step for metal sintering according to this embodiment).

[0116] As described above, a multilayer ceramic capacitor having a base electrode layer formed thereon but before a plating layer was formed was fabricated as a sample.

[0117] B. Sample Evaluation (Evaluation of Glass Lift) The LT cross section, which is the polished surface of the prepared sample, was observed under an SEM at 3000x magnification. A state in which the surface glass layer protruded upward above the adjacent Cu particles in the planar direction of the surface glass layer (the LW cross section direction perpendicular to the LT cross section) was determined to be glass lift. This will be described in detail with reference to FIG. 9 . FIG. 9 is a schematic diagram illustrating the evaluation index for glass lift. As shown in FIG. 9 , attention is first focused on one surface glass layer 45a. Next, attention is focused on Cu particles 40a and 40b adjacent to the surface glass layer 45a in the longitudinal direction z (the LW cross section direction perpendicular to the LT cross section). A contact surface 40c connecting the top surface of Cu particle 40a and the top surface of Cu particle 40b is drawn. Glass lift 46 was determined to have occurred when the surface glass layer 45a protruded beyond the contact surface 40c outside the base electrode layer 52, as shown in FIG. 9 .

[0118] (Evaluation of Blisters) The prepared samples were photographed using a laser microscope at a magnification that allowed the entire chip to be captured, and the presence or absence of blisters in the base electrode layer was observed. Specifically, if a bulge with a diameter of 15 μm or more was found in the base electrode layer, it was determined that blisters had occurred in the sample.

[0119] (Evaluation of Flatness) As shown in (a) of FIG. 4, the LT surface of the prepared sample was polished down to the portion where the internal electrode layer was first exposed, and the thickness t1 of the first base electrode layer 32a was measured using a metallurgical microscope in the LT cross section. The thickness t1 was measured over 15 fields of view, and the average value was used as the evaluation thickness t1. Furthermore, the LT surface of the prepared sample was polished down to 1 / 2 of the width direction y, and the thickness t2 of the first base electrode layer 32a was measured using a metallurgical microscope in the LT cross section. The thickness t2 was measured over 15 fields of view, and the average value was used as the evaluation thickness t2. The evaluation thickness t2 / evaluation thickness t1 was calculated to evaluate flatness. A value of t2 / t1 less than 4.7 was determined to be flat.

[0120] (Evaluation of C in Glass Contained in Base Electrode Layer) Figure 10 is a schematic diagram showing a thin sample to be analyzed, extracted from the base electrode layer. A thin sample S was extracted from the surface of the base electrode layer using a focused ion beam (FIB) from a portion of the end face (first end face 12e in Figure 10) of the prepared sample, where the thickness t3 of the base electrode layer was 3 μm or more and glass 45 was included. The thin sample S was rectangular, with an L dimension in the length direction z of 3 μm, a W dimension in the width direction y of 80 nm, and a T dimension in the height direction x of 5 μm.

[0121] Next, an STEM (Scanning Transmission Electron Microscope) image was taken of the LT surface of the thin sample S, and the Cu particles and the glass were identified by contrast. 2 In the same field of view within the range of , the surface glass and the internal glass were identified. The glass facing the surface of the base electrode layer was identified as the surface glass. The glass not facing the surface of the base electrode layer but located inside the base electrode layer and independent of the surface glass was identified as the internal glass.

[0122] Next, point analysis was performed on the center of the surface glass and the center of the inner glass using an EDX (energy dispersive X-ray analysis) device. The point analysis was performed on two fields of view, field of view 1-1 and field of view 1-2. In Example 1, a Noran System 7 (Thermo Fisher Scientific Co., Ltd.) was used as the EDX device. The analysis conditions were as follows: Spot diameter: φ5.0 nm Time constant: Rate 1 Number of accumulations: 100

[0123] Based on the results of the point analysis, the following values ​​were calculated for each of Visual Field 1-1 and Visual Field 1-2. Rs (C content / content of element α) in the surface glass and Ri (C content / content of element α) in the inner glass were calculated, and (Ri-Rs) / Ri in (Formula 1) was calculated. In addition, C / Ba (ratio of C content / Ba content) in each of the surface glass and the inner glass was calculated. Furthermore, based on (Formula 2), the ratio Rc of the C content to the content of elements from the third period or later in the periodic table in the inner glass (C content / content of elements from the third period or later in the periodic table) was calculated.

[0124] C. Results Figure 11 is an SEM image of the appearance of the sample of Example 1. As shown in Figure 11, in the sample of Example 1, glass lifting and blisters did not occur in the base electrode layer. In the sample of Example 1, t1 = 5.3 μm and t2 = 11.7 μm. Since t2 / t1 = 2.2, which is less than 4.7, the base electrode layer was generally flat.

[0125] As described above, glass lifting and blisters did not occur in the sample of Example 1. This is believed to be because the base electrode layer was formed in conjunction with the process of incorporating C into the glass according to the present embodiment. That is, before firing the laminate at approximately 700°C and then performing the firing process for metal sintering, a process of raising the temperature to 630°C, which is within ±15°C of the glass softening point, and then leaving it to stand for 8 minutes was performed. It is believed that this process of incorporating C into the glass allowed the C remaining in the unsintered base electrode layer to be incorporated into the surface glass and inner glass. Therefore, it is believed that the amount of C in contact with the gas phase of the firing atmosphere was reduced before the firing process for metal sintering was performed. This prevented the C in contact with the gas phase of the firing atmosphere from rapidly gasifying during firing, thereby suppressing defects such as glass lifting and blisters.

[0126] Furthermore, it is believed that the base electrode layer paste used in Example 1 contained an ethyl cellulose-based resin in particular, and therefore the base electrode layer was generally flat.

[0127] Furthermore, in the sample of Example 1, the evaluation of C in the glass contained in the base electrode layer yielded the results shown in Table 1 below.

[0128]

[0129] As described above, for the sample of Example 1, defects such as glass lifting and blisters were suppressed, and the base electrode layer was generally flat. Therefore, from the results in Table 1 for Example 1, it was found that defects such as glass lifting and blisters could be suppressed by satisfying the following (Equation 1): (Ri - Rs) / Ri ≦ 29.5% (Equation 1). Note that blisters tend to occur more easily in thick portions of the base electrode layer. In Example 1, as described above, the base electrode layer was formed flat overall, and thick portions were suppressed. From this point of view, it is believed that the occurrence of blisters was suppressed.

[0130] (2) Comparative Example 1 Comparative Example 1, which differs from the present embodiment, is described below. A. Preparation of Sample A sample of Comparative Example 1 was prepared by the same process as in Example 1, except that in the step corresponding to the step of introducing C into glass according to the present embodiment, the laminate to which the base electrode layer was applied before sintering was heated in a nitrogen atmosphere to 550°C, which is lower than the glass softening point of -15°C.

[0131] B. Evaluation of Sample Various evaluations of the sample of Comparative Example 1 were the same as those of Example 1. However, point analysis using EDX was performed on two visual fields, visual field 2-1 and visual field 2-2.

[0132] C. Results Figure 12 is an SEM image of the appearance of the sample of Comparative Example 1. As shown in Figure 12, in the sample of Comparative Example 1, glass lift occurred in the base electrode layer, but no blisters occurred. In the sample of Comparative Example 1, t2 / t1 = 2.1, which is less than 4.7, so the base electrode layer was generally flat.

[0133] As described above, glass lifting occurred in the sample of Comparative Example 1. However, no blisters were observed. In Comparative Example 1, in the process corresponding to the process of introducing C into the glass according to the present embodiment, the laminate was heated only to 550°C in a nitrogen atmosphere. This firing temperature of 550°C is lower than the firing temperature of 630°C in Example 1 and is outside the range of the glass softening point ±15°C. Therefore, it is believed that the glass powder in the unsintered base electrode layer did not generally soften or flow. Therefore, it is believed that the C remaining in the unsintered base electrode layer was either difficult to incorporate into the surface glass and the inner glass, or that only a small amount of the remaining C was incorporated into the surface glass and the inner glass. For this reason, it is believed that the C that could come into contact with the gas phase of the firing atmosphere could not be sufficiently reduced before the firing process for metal sintering was performed. As a result, it is believed that the C in contact with the gas phase of the firing atmosphere was rapidly gasified during firing, causing the glass to expand, resulting in glass lifting. On the other hand, it is believed that even if only a portion of the remaining C was taken into the surface glass and the inner glass, the amount of gas generated by the combustion of C was relatively small and no blisters were formed.

[0134] Furthermore, it is believed that the base electrode layer was generally flat because the paste for the base electrode layer used in Comparative Example 1 contained an ethyl cellulose-based resin in particular. Therefore, from the results of Example 1 and Comparative Example 1, it was found that it is preferable to satisfy the following (Equation 3): t2 / t1≦2.2 (Equation 3)

[0135] Furthermore, in the sample of Comparative Example 1, the results of the evaluation of C in the glass contained in the base electrode layer are shown in Table 2 below.

[0136]

[0137] As described above, glass lifting occurred in the sample of Comparative Example 1. From the results in Table 2 for Comparative Example 1, (Ri-Rs) / Ri was 43.4% in visual field 2-1, and (Ri-Rs) / Ri was 62.0% in visual field 2-2. Therefore, the sample of Comparative Example 1 did not satisfy (Equation 1) obtained in Example 1.

[0138] Furthermore, in the samples of Example 1 and Comparative Example 1, the base electrode layer paste contains an ethyl cellulose-based resin that is resistant to thermal decomposition. Therefore, it is believed that a large amount of C remains in the unsintered base electrode layer even after the degreasing process. It is believed that the remaining C on the surface of the unsintered base electrode layer is gasified on the surface during the metal sintering firing process and released to the outside. Furthermore, the remaining C present in gaps between the surface of the surface glass and the Cu powder is gasified during the metal sintering firing process and released to the outside by traversing the surface glass. Furthermore, the remaining C on the surface of the inner glass and in gaps between the inner glass and the Cu powder is trapped inside the unsintered base electrode layer and therefore is less likely to come into contact with the gas phase of the combustion atmosphere and is therefore less likely to be gasified. Therefore, the incorporation of C near the inner glass into the inner glass is easier than the incorporation of C near the surface glass into the surface glass. For these reasons, C derived from the ethyl cellulose-based resin is often incorporated into the inner glass. Conversely, a large amount of C incorporated into the internal glass indicates that a resin in which C easily remains, such as an ethyl cellulose-based resin, was contained in the base electrode layer paste, which is the material for the base electrode layer. From the above, with reference to the Rc (C content / elements from the third period or later in the periodic table) of the internal glass in Tables 1 and 2, it was found that it is preferable to satisfy the following (Formula 2): Rc≧0.12 (Formula 2) Here, 0.12 is the Rc value of the internal glass of visual field 2-1, which has the smallest Rc value among the Rc values ​​of the internal glasses of visual field 1-1, visual field 1-2, visual field 2-1, and visual field 2-2. Furthermore, the Rc value of the internal glass of visual field 1-1, which has the largest Rc value among the Rc values ​​of the internal glasses of visual field 1-1, visual field 1-2, visual field 2-1, and visual field 2-2, is 0.23.

[0139] (3) Comparative Example 2 Comparative Example 2, which differs from the present embodiment, is described below. A. Sample Preparation The base electrode layer paste of Comparative Example 2 differs from Example 1 in that it does not contain an ethyl cellulose-based resin in the resin. An acrylic resin, Cu powder, glass powder, and solvent were prepared. The Cu powder, glass powder, and solvent were the same as those of Example 1. The acrylic resin, Cu powder, glass powder, and solvent were blended and mixed in a planetary mixer, and then dispersed and kneaded in a three-roll mill to prepare a base electrode layer paste sample of Comparative Example 2.

[0140] The laminate on which the dried film was formed after the drying and degreasing processes was fired at 700°C in a nitrogen atmosphere (corresponding to the firing process for metal sintering in the present embodiment) without carrying out a process corresponding to the process of introducing C into the glass in the present embodiment. Except for this point, a sample of Comparative Example 2 was produced by the same process as in Example 1.

[0141] B. Evaluation of Sample Various evaluations of the sample of Comparative Example 2 were the same as those of Example 1. However, point analysis using EDX was performed on one visual field, visual field 3-1.

[0142] C. Results No glass lifting or blisters occurred in the base electrode layer in the sample of Comparative Example 2. In the sample of Comparative Example 2, t2 / t1 was 4.7, which was 4.7 or more, so the base electrode layer was not flat and there was a problem with flatness.

[0143] In the sample of Comparative Example 2, a process equivalent to the process of introducing C into the glass as in Example 1 and Comparative Example 1 was not carried out, but as described above, glass lifting and blisters did not occur. This is thought to be because the paste for the base electrode layer did not contain an ethyl cellulose-based resin that is resistant to thermal decomposition, and therefore relatively little C remained in the unsintered base electrode layer. On the other hand, in the sample of Comparative Example 2, the absence of an ethyl cellulose-based resin in the paste for the base electrode layer is thought to have caused problems with the flatness of the base electrode layer.

[0144] In addition, in the sample of Comparative Example 2, the results of the evaluation of C in the glass contained in the base electrode layer are shown in Table 3 below.

[0145]

[0146] As described above, although the embodiments of the present invention have been disclosed in the above description, the present invention is not limited thereto. In other words, various modifications can be made to the above-described embodiments in terms of mechanism, shape, material, quantity, position, arrangement, etc., without departing from the scope of the technical idea and purpose of the present invention, and such modifications are included in the present invention.

[0147] <Other Modifications>

[0148] (1) Regarding the External Electrode In the above embodiment, the external electrode 30 includes a base electrode layer 32 and a plating layer 34 on the base electrode layer 32. However, the configuration of the external electrode 30 is not limited to this, and the external electrode may include only the base electrode layer 32 without including the plating layer 34. This is the same as the above embodiment except that the plating layer 34 is not formed.

[0149] (2) Gases that cause blisters, glass lifting, etc. In the above embodiment, CO2, which is formed by gasifying remaining C, is cited as a gas that causes blisters, glass lifting, etc. However, gases that cause blisters, glass lifting, etc. may also include, for example, SO2, NO2, NO2, Cl2, etc., which are derived from ions contained as impurities in the Cu powder.

[0150] (3) Other Multilayer Ceramic Capacitors In the above embodiments, a two-terminal multilayer ceramic capacitor having two terminals, a first external electrode 30a and a second external electrode 30b, has been described as the multilayer ceramic capacitor to be manufactured. However, the scope of application of the present invention is not limited to two-terminal multilayer ceramic capacitors, but also includes multilayer ceramic electronic components that require suppression of external electrode defects such as blisters and glass lift. Therefore, the present invention may also be applied to, for example, three-terminal multilayer ceramic capacitors.

[0151] For example, a three-terminal multilayer ceramic capacitor includes a laminate 12 similar to those in the first and second embodiments and first to fourth external electrodes. The internal electrode layers 16 include a first internal electrode layer extending to the first end face 12e and the second end face 12f, and a second internal electrode layer extending to the first side face 12c and the second side face 12d. A first external electrode is disposed on the first end face 12e of the laminate 12. The first external electrode is electrically connected to the first internal electrode layer exposed at the first end face 12e of the laminate 12. A second external electrode is disposed on the second end face 12f of the laminate 12. The second external electrode is electrically connected to the first internal electrode layer exposed at the second end face 12f of the laminate 12. A third external electrode is disposed on the first side face 12c of the laminate 12. The third external electrode is electrically connected to the second internal electrode layer exposed at the first side surface 12c of the laminate 12. A fourth external electrode is disposed on the second side surface 12d of the laminate 12. The fourth external electrode is electrically connected to the second internal electrode layer exposed at the second side surface 12d of the laminate 12.

[0152] <1> A multilayer ceramic capacitor comprising: a laminate in which a plurality of ceramic layers and a plurality of internal electrode layers are alternately stacked in a predetermined stacking direction; and external electrodes connected to the plurality of internal electrode layers at portions where the plurality of internal electrode layers are exposed in the laminate, wherein the external electrodes include base electrode layers formed on the laminate, and the base electrode layer includes a conductive metal and a glass containing Si and an element α as a main component, wherein the element α is Ba or Sr, and the glass includes a surface glass facing an external electrode surface of the external electrode, and an internal glass that does not face the external electrode surface, is located inside the external electrode, and is independent of the surface glass, and a ratio Rs of the content of C to the content of the element α in the surface glass (C content / element α content) and a ratio Ri of the content of C to the content of the element α in the internal glass satisfy the following (Formula 1): (Ri-Rs) / Ri≦29.5% (Formula 1).

[0153] <2> The multilayer ceramic capacitor according to <1>, wherein the inner glass and the surface glass are located at the closest positions in the same field of view within a predetermined range in a cross section of the base electrode layer in the thickness direction.

[0154] <3> The multilayer ceramic capacitor according to <1>, wherein a ratio Rc of the C content to the content of elements of the third period or later in the periodic table in the inner glass (C content / content of elements of the third period or later in the periodic table) satisfies the following (Formula 2): Rc≧0.12 (Formula 2)

[0155] <4> The multilayer ceramic capacitor according to any one of <1> to <3>, wherein a maximum thickness t2 of the external electrode in a length direction perpendicular to the stacking direction, with respect to an end face of the laminate, and a thickness t1 of the external electrode formed on an internal electrode layer located outermost in the stacking direction among the plurality of internal electrode layers, with respect to the end face of the laminate, satisfy the following (Formula 3): t2 / t1≦2.2 (Formula 3).

[0156] <5> The multilayer ceramic capacitor according to any one of <1> to <3>, wherein the external electrodes include a plating layer disposed on the base electrode layer.

[0157] <6> The multilayer ceramic capacitor according to any one of <1> to <5>, wherein the conductive metal is Cu particles.

[0158] REFERENCE SIGNS LIST 10: Multilayer ceramic capacitor 12: Laminate 12a, 12b: First and second main surfaces 12c, 12d: First and second side surfaces 12e: First and second end surfaces 14: Ceramic layer 16: Internal electrode layer 16a, 16b: First and second internal electrode layers 30: External electrodes 30a, 30b: First and second external electrodes 31: Base electrode layer paste 31a: Unsintered base electrode layer 31b: Surface 32: Base electrode layer 32a, 32b: First and second base electrode layers 33: Base electrode layer surface 34: Plating layer 34a, 34b: First and second plating layers 40: Cu particles 42: Cu powder 43: Glass powder 43a : Surface glass powder 43b: Internal glass powder 44: Softened glass 44a: Surface softened glass 44b: Internal softened glass 45: Glass 45a: Surface glass 45b: Internal glass 46: Glass float C: Carbon O: Oxygen x: Height direction y: Width direction z: Length direction

Claims

1. A multilayer ceramic capacitor comprising: a laminate in which a plurality of ceramic layers and a plurality of internal electrode layers are alternately stacked in a predetermined stacking direction; and external electrodes connected to the plurality of internal electrode layers at portions where the plurality of internal electrode layers are exposed in the laminate; wherein the external electrodes include base electrode layers formed on the laminate, and the base electrode layer includes a conductive metal and glass containing Si and an element α as a main component, the element α being Ba or Sr; and the glass including a surface glass facing the external electrode surface of the external electrode, and an internal glass that does not face the external electrode surface, is located inside the external electrode, and is independent of the surface glass; and the ratio Rs of the C content to the element α in the surface glass (C content / element α content) and the ratio Ri of the C content to the element α in the internal glass satisfy the following (Equation 1): (Ri-Rs) / Ri≦29.5% (Equation 1).

2. The multilayer ceramic capacitor according to claim 1, wherein the inner glass and the surface glass are located at the closest positions in the same field of view within a predetermined range in a cross section of the base electrode layer in the thickness direction.

3. The multilayer ceramic capacitor according to claim 1, wherein the ratio Rc of the carbon content to the content of elements in the third period or later of the periodic table in the inner glass (carbon content / elements in the third period or later of the periodic table) satisfies the following (formula 2): Rc≧0.12 (formula 2).

4. A multilayer ceramic capacitor as described in any one of claims 1 to 3, wherein the maximum thickness t2 of the external electrode in the length direction perpendicular to the stacking direction, with respect to the end face of the laminate, and the thickness t1 of the external electrode formed on the internal electrode layer located outermost in the stacking direction among the plurality of internal electrode layers, with respect to the end face of the laminate, in the length direction, satisfy the following (Formula 3): t2 / t1≦2.2... (Formula 3).

5. A multilayer ceramic capacitor according to any one of claims 1 to 3, wherein the external electrodes include a plating layer disposed on the base electrode layer.

6. A multilayer ceramic capacitor according to any one of claims 1 to 5, wherein the conductive metal is Cu particles.

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