Multilayer ceramic capacitor

Abstract

A multilayer ceramic capacitor according to the present disclosure is provided with: an external electrode; and a laminate which comprises a plurality of stacked dielectric layers and a plurality of stacked internal electrode layers. The external electrode comprises a plating layer and a base electrode layer. The base electrode layer contains glass. The glass contains an alkaline earth metal. With respect to the base electrode layer, if the mass proportion of the alkaline earth metal in the glass present in the central part in the thickness direction is taken as 100, the mass proportion of the alkaline earth metal in the glass present in the vicinity of the plating layer-side surface is not less than 90 but less than 100.

Description

Multilayer ceramic capacitors

[0001] The present disclosure relates to multilayer ceramic capacitors.

[0002] As described in Patent Document 1, the external electrodes of a multilayer ceramic capacitor generally include a base electrode layer formed on the surface of a laminate such as a ceramic body, and a plating layer applied to the base electrode layer. The base electrode layer is often formed from a conductive paste containing glass to achieve densification. The glass used in the base electrode layer is designed to satisfy various required properties, such as filling pores inside the external electrode to form a dense film, acting as an auxiliary agent in the sintering process, adhering to the body after firing, and possessing chemical durability.

[0003] Japanese Patent Application Laid-Open No. 2021-019018

[0004] Multilayer ceramic capacitors are prone to solder explosions when the base electrode layers of the external electrodes contain glass. Solder explosions occur when, for example, a multilayer ceramic capacitor is mounted on a circuit board and fixed by soldering. The heat of soldering causes moisture or plating solution that has penetrated into the base electrode layer to rapidly evaporate, causing the solder on the outer layer to fly off, potentially resulting in a short circuit.

[0005] An object of the present disclosure is to provide a multilayer ceramic capacitor having external electrodes in which solder explosions are suppressed.

[0006] A multilayer ceramic capacitor according to the present disclosure includes an external electrode and a laminate including a plurality of laminated dielectric layers and a plurality of internal electrode layers. The external electrode includes a plating layer and a base electrode layer. The base electrode layer includes glass. The glass includes an alkaline earth metal. In the base electrode layer, when the mass fraction of the alkaline earth metal in the glass present in the center portion in the thickness direction is taken as 100, the mass fraction of the alkaline earth metal in the glass present near the surface on the plating layer side is 90 or more but less than 100.

[0007] According to the present disclosure, it is possible to provide a multilayer ceramic capacitor having external electrodes in which solder explosions are suppressed.

[0008] Fig. 1 is a perspective view showing the appearance of a multilayer ceramic capacitor according to the present disclosure. Fig. 2 is a cross-sectional view of the multilayer ceramic capacitor of Fig. 1 as viewed from the direction of the arrows along line II-II. Fig. 3 is a cross-sectional view of the multilayer ceramic capacitor of Fig. 1 as viewed from the direction of the arrows along line III-III. Fig. 4 is a cross-sectional view showing the layer structure of an external electrode. Fig. 5 is a schematic diagram illustrating the microstructure of a base electrode layer. Fig. 6 is a cross-sectional view illustrating the central portion, the surface vicinity, and the interface vicinity of the base electrode layer.

[0009] Hereinafter, the multilayer ceramic capacitor of the present disclosure will be described with reference to the drawings. In the following description of each embodiment, the same or corresponding parts in the drawings will be denoted by the same reference numerals, and description thereof will not be repeated.

[0010] <Multilayer Ceramic Capacitor> A multilayer ceramic capacitor includes an external electrode and a laminate including a plurality of laminated dielectric layers and a plurality of internal electrode layers. The external electrode is disposed on the laminate with the base electrode layer side.

[0011] Fig. 1 is a perspective view showing the appearance of a multilayer ceramic capacitor according to the present disclosure. Fig. 2 is a cross-sectional view of the multilayer ceramic capacitor of Fig. 1 as viewed from the direction of the arrows along line II-II. Fig. 3 is a cross-sectional view of the multilayer ceramic capacitor of Fig. 1 as viewed from the direction of the arrows along line III-III.

[0012] As shown in FIGS. 1 to 3 , a multilayer ceramic capacitor 100 according to the present disclosure includes a laminate 110 and an external electrode 120. As shown in FIGS. 2 and 3 , the laminate 110 includes a plurality of dielectric layers 130 and a plurality of internal electrode layers 140 that are alternately stacked one layer at a time along a stacking direction T. The laminate 110 has a first main surface 111 and a second main surface 112 that face each other in the stacking direction, a first side surface 113 and a second side surface 114 that face each other in a width direction perpendicular to the stacking direction, and a first end surface 115 and a second end surface 116 that face each other in a length direction perpendicular to the stacking direction and the width direction. The laminate 110 is partitioned into an inner layer portion C, a first outer layer portion X1, a second outer layer portion X2, a first side margin portion S1, a second side margin portion S2, a first end margin portion E1, and a second end margin portion E2.

[0013] As shown in Figures 1 to 3, the external electrode 120 is provided on the surface of the laminate 110. As shown in Figure 2, the external electrode 120 includes a base electrode layer 121 and a plating layer 122. The external electrode 120 can be composed of a first external electrode 120A and a second external electrode 120B. The first external electrode 120A is provided on the first end face 115. The second external electrode 120B is provided on the second end face 116.

[0014] The first external electrode 120A is formed on the first end face 115 of the laminate 110 so as to be electrically connected to the first internal electrode layer 140A, and extends from the first end face 115 to the first main face 111 and the second main face 112 and the first side face and the second side face. The second external electrode 120B is formed on the second end face 116 of the laminate 110 so as to be electrically connected to the second internal electrode layer 140B, and extends from the second end face 116 to the first main face 111 and the second main face 112 and the first side face and the second side face.

[0015] As shown in Figure 4, the first external electrode 120A (second external electrode 120B) has a first base electrode layer 121A (second base electrode layer 121B), a first lower plating layer 122B (second lower plating layer 122D) arranged on the first base electrode layer 121A (second base electrode layer 121B), and a first upper plating layer 122A (second upper plating layer 122C) arranged on the first lower plating layer 122B (second lower plating layer 122D).

[0016] 5 is a schematic diagram illustrating the microstructure of the base electrode layer 121. As shown in FIG. 5, the base electrode layer 121 includes glass 150. The base electrode layer may be a sintered layer of a conductive paste including a glass composition. The conductive paste will be described later.

[0017] The glass 150 may include, for example, borosilicate glass. Borosilicate glass is a glass containing boron oxide (B ２ O ３ ) and silicon oxide (SiO ２ ) as a network-forming oxide.

[0018] Glass 150 includes an alkaline earth metal. The alkaline earth metal may include at least one element selected from the group consisting of calcium (Ca), strontium (Sr), and barium (Ba). The alkaline earth metal may further include magnesium (Mg). The alkaline earth metal may be included in glass 150 as a network modifier oxide (e.g., CaO, SrO, BaO, MgO, etc.).

[0019] In the thickness direction (direction of arrow T1 in FIG. 4 ), when the mass ratio of the alkaline earth metal in the glass present in the center portion (hereinafter also referred to as the first ratio) is 100, the mass ratio of the alkaline earth metal in the glass present near the surface on the plating layer side (hereinafter also referred to as the second ratio) is 90 or more and less than 100. When the second ratio is within the above range, solder explosion tends to be easily suppressed. The mass ratio of the alkaline earth metal in the glass is the mass ratio of the alkaline earth metal contained in the glass based on the mass of the glass. The mass ratio of the alkaline earth metal in the glass is measured according to the method described in the Examples section below.

[0020] The central portion and the vicinity of the surface will be described with reference to Fig. 6. Fig. 6 is an enlarged cross-sectional view of region P surrounded by a dotted line in the base electrode layer shown in Fig. 4. As shown in Fig. 6, when the base electrode layer 121 is divided into 10 equal regions in the thickness direction and the regions are designated as regions 1, 2, ..., 10 in order from the plating layer side, regions 1 and 2 are referred to as the vicinity of the surface, and regions 3 to 8 are referred to as the central portion.

[0021] Analysis of the external electrodes of multilayer ceramic capacitors revealed that the mass percentage of alkaline earth metals in the glass near the surface of the base electrode layer tended to be lower than the mass percentage of alkaline earth metals in the glass near the center. This is presumably due to the fact that, during the plating process to form the plating layer, the base electrode layer comes into contact with water or a plating solution, causing the alkaline earth metals in the glass to dissolve into the plating solution, and the accompanying movement of other components changes the glass composition. As a result, the mass percentage of alkaline earth metals in the glass near the surface decreases, corroding the glass, making it easier for water and plating solution to penetrate the base electrode layer and increasing the likelihood of solder explosions. In the multilayer ceramic capacitor of the present disclosure, the difference in the alkaline earth metal content in the glass between the center and the surface on the plating layer side of the base electrode layer in the thickness direction is small, making solder explosions more likely to be suppressed. The ease of suppressing solder explosions was evaluated according to the method described in the Examples section below.

[0022] When the first ratio is 100, the second ratio is preferably 96 or more from the viewpoint of suppressing solder explosion. The second ratio may be, for example, 98 or less.

[0023] From the viewpoint of suppressing solder explosion, the base electrode layer 121 preferably has a mass ratio of alkaline earth metal in the glass present in region 1 of 90 or more but less than 100 when the mass ratio of alkaline earth metal in the glass present in region 6 is taken as 100.

[0024] In the thickness direction of the base electrode layer 121, when the first ratio is 100, the mass ratio of the alkaline earth metal in the glass present near the surface on the laminate 110 side (hereinafter also referred to as near the interface) (hereinafter also referred to as the third ratio) can be 105 or more and 115 or less. When the third ratio is in the above range, a decrease in the strength of the laminate described below tends to be easily suppressed. The vicinity of the interface is the above-mentioned region 9 to 10.

[0025] Analysis of the external electrodes of multilayer ceramic capacitors revealed that the mass percentage of alkaline earth metals in the glass present near the interface with the laminate in the base electrode layer tends to be higher than the mass percentage of alkaline earth metals in the glass present in the central portion. This is presumably because the glass present near the interface with the laminate facilitates diffusion of alkaline earth metals contained in the laminate into the base electrode layer. Therefore, external electrodes with a small difference in the content of alkaline earth metals in the glass present in the central portion and near the interface in the thickness direction of the base electrode layer are thought to be more likely to suppress a decrease in the strength of the laminate. The strength of the laminate was evaluated according to the method described in the Examples section below.

[0026] When the first ratio is taken as 100, the third ratio is preferably 112 or less in terms of preventing a decrease in strength of the laminate.

[0027] The glass 150 may further contain an alkali metal. The alkali metal may be, for example, at least one element selected from lithium (Li), sodium (Na), and potassium (K). The alkali metal may be a network modifier oxide (e.g., Li ２ O, Na ２ O.K. ２ O) in the glass 150.

[0028] The glass 150 may contain oxides other than those mentioned above, such as transition metal element oxides, zinc oxide (ZnO), aluminum oxide (Al ２ O ３ ) and bismuth oxide (Bi ２ O ３ ) may be included.

[0029] The glass 150 may further include a metal oxide, such as copper oxide (CuO).

[0030] The base electrode layer 121 may further contain at least one conductive component selected from the group consisting of copper (Cu), nickel (Ni), and a Cu—Ni alloy. The conductive component may be a conductive powder. The conductive component may be contained in a region 151 other than the glass 150 (hereinafter also referred to as a conductive region).

[0031] When the base electrode layer 121 is formed from a conductive paste described below, the conductive region 151 may include a metal sintered body formed by sintering a conductive powder contained in the conductive paste.

[0032] The thickness of the base electrode layer 121 may be, for example, 10 μm or more and 50 μm or less, and preferably 15 μm or more and 40 μm or less. The thickness of the base electrode layer 121 is measured as follows. First, the multilayer ceramic capacitor 100 is polished to expose a cross section perpendicular to the width direction W. The exposed cross section is observed with a microscope and measured. The measurement position is the center part in the stacking direction T.

[0033] The base electrode layer 121 is likely to be thin near the edges formed on the first main surface 111, the second main surface 112, the first side surface 113, and the second side surface 114, and is therefore susceptible to the effects of the plating solution. By having the alkaline earth metal content of the glass contained in the base electrode layer 121 be the first ratio and the second ratio described above, solder explosion can be suppressed even near the edges where the thickness is likely to be thin.

[0034] The plating layer 122 may include, for example, nickel (Ni), Cu, silver (Ag), gold (Au), and tin (Sn), or an alloy containing these metals. The plating layer 122 may be formed of multiple layers made of different components. The plating layer 122 may have a two-layer structure consisting of an upper plating layer (the first upper plating layer 122A and the second upper plating layer 122C are also collectively referred to as upper plating layers) and a lower plating layer (the first lower plating layer 122B and the second lower plating layer 122D are also collectively referred to as upper plating layers). The lower plating layers are each disposed on an underlying electrode layer to prevent the underlying electrode layer from being eroded by solder when the multilayer ceramic capacitor is mounted. The lower plating layer may be, for example, a Ni plating layer. The upper plating layer is disposed on the lower plating layer. The upper plating layer may be, for example, a Sn plating layer. The Sn plating layer has good wettability with solder containing Sn, and therefore can improve the mountability when mounting the multilayer ceramic capacitor.

[0035] The upper and lower plating layers may have a thickness of, for example, 0.5 μm or more and 10 μm or less, preferably 5.5 μm or less, and more preferably 4.5 μm or less.

[0036] The thicknesses of the upper and lower plating layers are measured as follows. First, the multilayer ceramic capacitor 100 is polished using an FIB device to expose a cross section perpendicular to the width direction W. The exposed cross section is observed using a microscope, and the thicknesses of the above layers are measured. The measurement position is the center in the stacking direction T. The thickness of the upper plating layer may also be measured using a fluorescent X-ray film thickness meter.

[0037] The dielectric layer 130 has a plurality of crystal grains containing, for example, a BaTiO3-based perovskite compound. The dielectric material may be, for example, Ba in the crystal lattice of the BaTiO3-based perovskite compound. 2+ A part of the rare earth element ions Re 3+ Examples of BaTiO3-based perovskite compounds include BaTiO3 and BaTiO3. 2+ and Ti 4+ At least one of the following is Ca 2+ and Zr 4+ and those substituted with other ions such as:

[0038] The thickness of each of the plurality of dielectric layers 130 included in the inner layer portion C is preferably 0.4 μm or more and 0.8 μm or less, and more preferably 0.5 μm or more and 0.7 μm or less. In this specification, the thickness of each layer is the thickness at the center of the end face.

[0039] The multiple internal electrode layers 140 include multiple first internal electrode layers 140A connected to the first external electrode 120A and multiple second internal electrode layers 140B connected to the second external electrode 120B. As shown in Fig. 2, the first internal electrode layer 140A includes a counter electrode portion 141A facing the second internal electrode layer 140B via the dielectric layer 130, and a lead electrode portion 142A extending from the counter electrode portion 141A to the first end face 115 of the laminate 110. The second internal electrode layer 140B includes a counter electrode portion 141B facing the first internal electrode layer 140A via the dielectric layer 130, and a lead electrode portion 142B extending from the counter electrode portion 141B to the second end face 116 of the laminate 110.

[0040] A single capacitor is formed by the first internal electrode layer 140A and the second internal electrode layer 140B facing each other via the dielectric layer 130. The multilayer ceramic capacitor 100 can be said to be a plurality of capacitors connected in parallel via the first external electrode 120A and the second external electrode 120B.

[0041] The conductive material constituting the internal electrode layer 140 can be at least one metal selected from Ni, Cu, Ag, palladium (Pd), etc., or an alloy containing such a metal. The internal electrode layer 140 may further contain dielectric particles called a co-material.

[0042] The thickness of each of the plurality of internal electrode layers 140 is preferably 0.3 μm or more and 1.0 μm or less. The coverage rate, that is, the coverage rate of each of the plurality of internal electrode layers 140 covering the dielectric layer 130 without any gaps, is preferably 50% or more and 95% or less.

[0043] The thickness of each of the dielectric layers 130 and the internal electrode layers 140 included in the inner layer portion C is measured as follows. First, the multilayer ceramic capacitor 100 is polished to expose a cross section perpendicular to the longitudinal direction L. The exposed cross section is observed with a scanning electron microscope. Next, the thickness of each of the dielectric layers 130 and the internal electrode layers 140 is measured along a center line along the stacking direction T that passes through the center of the exposed cross section, and two lines drawn equally spaced on each side of this center line, for a total of five lines. The average of the five measured values ​​of the dielectric layer 130 is defined as the thickness of the dielectric layer 130. The average of the five measured values ​​of the internal electrode layer 140 is defined as the thickness of the internal electrode layer 140.

[0044] In addition, at each of the upper, central and lower parts located on the boundary lines dividing the exposed cross section into four equal parts in the stacking direction T, the thicknesses of the dielectric layers 130 and the internal electrode layers 140 on the above five lines may be measured, and the average value of the measured values ​​of the dielectric layers 130 may be used as the thickness of the dielectric layers 130, and the average value of the measured values ​​of the internal electrode layers 140 may be used as the thickness of the internal electrode layers 140.

[0045] The first outer layer portion X1 and the second outer layer portion X2 are respectively arranged between the first main surface 111 of the laminate 110 and the internal electrode layer 140 closest to the first main surface 111, and between the second main surface 112 and the internal electrode layer 140 closest to the second main surface 112. The internal layer portion C is arranged in a region sandwiched between the two first outer layer portion X1 and second outer layer portion X2.

[0046] The inner layer portion C has a capacitance due to the opposing electrode portion 141A of the first inner electrode layer 140A and the opposing electrode portion 141B of the second inner electrode layer 140B being stacked in the stacking direction T. The first outer layer portion X1 is located on the first main surface 111 side of the inner layer portion C in the stacking direction T. The second outer layer portion X2 is located on the second main surface 112 side of the inner layer portion C in the stacking direction T.

[0047] The first side margin S1 is located on the first side surface 113 side of the inner layer portion C in the width direction W. The second side margin S2 is located on the second side surface 114 side of the inner layer portion C in the width direction W. The first end margin E1 is located on the first end surface 115 side of the inner layer portion C in the length direction L. The second end margin E2 is located on the second end surface 116 side of the inner layer portion C in the length direction L.

[0048] From the viewpoint of miniaturizing the multilayer ceramic capacitor 100, it is preferable that the dimension in the width direction W of the first side margin portion S1, the dimension in the width direction W of the second side margin portion S2, the dimension in the length direction L of the first end margin portion E1, and the dimension in the length direction L of the second end margin portion E2 are each small enough to prevent a decrease in the insulation resistance of the multilayer ceramic capacitor 100.

[0049] The multilayer ceramic capacitor 100 has a length L dimension of 2.0 mm or less, a width W dimension of 1.25 mm or less, and a stacking direction T dimension of 1.25 mm or less. The external dimensions of the multilayer ceramic capacitor 100 can be measured by observing the multilayer ceramic capacitor 100 with an optical microscope.

[0050] Ceramic slurry is first prepared when manufacturing the multilayer ceramic capacitor 100. Specifically, ceramic powder, a binder, a solvent, and the like are mixed in a predetermined compounding ratio to form the ceramic slurry.

[0051] Next, a ceramic green sheet is formed by forming the ceramic slurry onto a carrier film into a sheet using a die coater, a gravure coater, a microgravure coater, or the like.

[0052] Next, a mother sheet is formed. Specifically, a conductive paste is printed in a predetermined pattern on the ceramic green sheet by screen printing, gravure printing, or the like, to form a mother sheet having the predetermined conductive pattern on the ceramic green sheet.

[0053] As the mother sheet, in addition to the mother sheet having a conductive pattern, a ceramic green sheet having no conductive pattern formed thereon is also prepared.

[0054] Next, the mother sheets are stacked. Specifically, a predetermined number of mother sheets that do not have a conductive pattern and that form the first outer layer portion X1 are stacked, and then a plurality of mother sheets that have a conductive pattern and that form the inner layer portion C are stacked in order on top of these, and then a predetermined number of mother sheets that do not have a conductive pattern and that form the second outer layer portion X2 are stacked on top of these, thereby forming a mother sheet group.

[0055] Next, the mother sheets are pressed together by a hydrostatic press or a rigid press in the stacking direction to form a mother laminate.

[0056] Next, the mother laminate is divided. Specifically, the mother laminate is divided into a matrix by press-cutting or dicing, and is separated into a plurality of unfired laminates.

[0057] Next, the green laminate is subjected to barrel polishing. Specifically, the green laminate is enclosed in a small box called a barrel together with media balls that are harder than the ceramic material, and the corners and ridges of the green laminate are rounded by rotating the barrel.

[0058] Next, the green laminate is fired. Specifically, the green laminate is heated to a predetermined temperature, thereby firing the dielectric ceramic material. The firing temperature is set appropriately depending on the type of dielectric ceramic material, and is set, for example, within the range of 900°C to 1300°C.

[0059] Next, a base electrode layer is formed on the surface of the laminate. Specifically, the base electrode layer 121 is formed by various thin film formation methods, various printing methods, a dipping method, or the like. For example, when forming the base electrode layer by the dipping method, a conductive paste is applied to the first end surface and the second end surface of the laminate, and then dried and baked. The baking temperature is set, for example, within a range of 700°C or higher and 800°C or lower. The base electrode layer can be a sintered layer of the conductive paste.

[0060] The conductive paste may contain a glass composition, a conductive component, and an organic component. The glass composition may be in a powder state. The organic component may include, for example, a vehicle and an additive. The vehicle may include, for example, a resin and an organic solvent. The additive may include, for example, a dispersant and a rheology control agent. The organic material may be appropriately selected from materials commonly used as the organic material for conductive pastes.

[0061] The glass composition contained in the conductive paste contains, when expressed in terms of mass ratio, Li ２ O 0 to 2 mass%, Na ２ O 0 to 8 mass%, CaO 1 to 8 mass%, SrO 0 to 8 mass%, BaO 20 to 60 mass%, B ２ O ３ 16 to 28 mass % of SiO ２ 5 to 12 mass % of Al ２ O ３ 12 to 20 mass % of TiO ２ and CuO in the range of 0 to 5.0 mass %, the total of which is 100 mass %.

[0062] The glass composition contained in the conductive paste preferably contains Li from the viewpoint of suppressing solder explosion when the composition is expressed in mass ratio. ２ O 0 to 2 mass%, Na ２ O 0 to 8 mass%, CaO 1 to 8 mass%, SrO 0 to 8 mass%, BaO 20 to 50 mass%, B ２ O ３ 19 to 28 mass % of SiO ２ 5 to 12 mass % of Al ２ O ３ 12 to 20 mass % of TiO ２and CuO in the range of 0 to 5.0 mass %, the total of which is 100 mass %.

[0063] The glass composition contained in the conductive paste is Li ２ O, Na ２ O, CaO, BaO and B ２ O ３ In the case where the composition contains B, it is preferable to use B from the viewpoint of suppressing solder explosion and a decrease in strength of the laminate. ２ O ３ Li for ２ O, Na ２ The total mass ratio of O, CaO and BaO (also referred to as the B ratio) is 1.17 to 2.61.

[0064] Next, a lower plating layer and an upper plating layer are sequentially formed by electrolytic plating so as to cover the base electrode layer. The plating layers may be formed by electrolytic plating using a barrel electroplating device. Before the plating process, the base electrode layer may be subjected to a surface treatment, such as sandblasting or water-repellent treatment. The formation of each of the above electrodes constitutes an external electrode.

[0065] The multilayer ceramic capacitor 100 of the present disclosure is manufactured through the above series of steps.

[0066] The present disclosure will be described in more detail below with reference to examples. In the examples, "%" and "parts" are by mass % and parts by mass unless otherwise specified.

[0067] [Measurement of the mass proportion of alkaline earth metal in glass] The cross sections of the external electrodes of the multilayer ceramic capacitors fabricated in the examples and comparative examples were observed using a high-resolution transmission electron microscope (HRTEM). Energy dispersive X-ray analysis (EDX) attached to the HRTEM was performed on 10 points each of the glass present near the surface, central portion, and interface of the base electrode layer, and the average ratio of the mass proportion of alkaline earth metal in the glass near the surface and near the interface to the central portion was calculated.

[0068] [Evaluation of Solder Explosions] Thirty-five multilayer ceramic capacitors were prepared for each of the examples and comparative examples. The prepared ceramic capacitors were heated to a temperature of 300°C twice. The external electrodes of the multilayer ceramic capacitors were observed using an optical microscope, and the number of solder explosions was counted. The evaluation results shown in Table 1 were based on the following evaluation criteria: 0: A, 1 to 2: B, 3 or more: C

[0069] [Evaluation of laminate strength] Thirty-five multilayer ceramic capacitors were prepared for each of the examples and comparative examples. According to JIS C 60068-2-21, the test method for printed circuit board bending resistance, the prepared multilayer ceramic capacitors were bent to 1.5 mm, and the number of cracks that occurred after the test was counted. The evaluation results shown in Table 1 were based on the following evaluation criteria: 0 cracks: G 1 or more cracks: NG

[0070] Examples 1 to 6, Comparative Examples 1 and 2 Conductive pastes were prepared by mixing glass compositions having the compositions shown in Table 1 with organic components. The prepared conductive pastes were applied to the first and second end faces of a laminate including a plurality of laminated dielectric layers and a plurality of internal electrode layers, dried, and then baked. After polishing (sandblasting, water-repellent treatment) the surfaces of the external electrodes, a Ni plating layer was formed, and then a Sn plating layer was formed, thereby preparing multilayer ceramic capacitors. The results are shown in Table 1.

[0071]

[0072] In the table, composition 1 and composition 2 have the following compositions: [Composition 1] Li ２ O 0 to 2 mass%, Na ２ O 0 to 8 mass%, CaO 1 to 8 mass%, SrO 0 to 8 mass%, BaO 20 to 60 mass%, B ２ O ３ 16 to 28 mass % of SiO ２ 5 to 12 mass % of Al ２ O ３ 12 to 20 mass % of TiO ２ and CuO in the range of 0 to 5.0 mass%, the total of which is 100 mass%. [Composition 2] Li ２ O 0 to 2 mass%, Na２ O 0 to 8 mass%, CaO 1 to 8 mass%, SrO 0 to 8 mass%, BaO 20 to 50 mass%, B ２ O ３ 19 to 28 mass % of SiO ２ 5 to 12 mass % of Al ２ O ３ 12 to 20 mass % of TiO ２ and CuO in the range of 0 to 5.0 mass %, the total of which is 100 mass %.

[0073] As shown in Table 1, Examples 1 to 6 according to the present disclosure had better evaluation results for solder explosion than Comparative Examples 1 and 2. It can be seen that the present disclosure provides external electrodes in which solder explosion is suppressed. Furthermore, in Examples 1 to 6, no decrease in the strength of the laminate was observed compared to Comparative Examples 1 and 2.

[0074] In the above-described embodiments, configurations that can be combined may be combined with each other.

[0075] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0076] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0077] (Item 1) A multilayer ceramic capacitor according to the present disclosure includes an external electrode and a laminate including a plurality of laminated dielectric layers and a plurality of laminated internal electrode layers. The external electrode includes a plating layer and a base electrode layer. The base electrode layer includes glass. The glass includes an alkaline earth metal. In the base electrode layer, when the mass fraction of the alkaline earth metal in the glass present in the center portion in the thickness direction is taken as 100, the mass fraction of the alkaline earth metal in the glass present near the surface on the plating layer side is 90 or more but less than 100.

[0078] (Item 2) In the base electrode layer of the multilayer ceramic capacitor according to item 1, the mass ratio of alkaline earth metal in the glass present near the surface on the plating layer side is 96 to 98.

[0079] (Item 3) In the multilayer ceramic capacitor according to item 1 or 2, the glass contains borosilicate glass.

[0080] (Item 4) In the multilayer ceramic capacitor according to item 3, the glass further contains an alkali metal.

[0081] (Item 5) In the multilayer ceramic capacitor according to item 3 or 4, the glass further contains copper oxide.

[0082] (Item 6) In the multilayer ceramic capacitor according to any one of items 1 to 5, the base electrode layer further contains at least one conductive component selected from the group consisting of copper, nickel, and copper-nickel alloys.

[0083] (Item 7) In the multilayer ceramic capacitor according to any one of Items 1 to 6, when the mass ratio of the alkaline earth metal in the glass present in the center portion in the thickness direction of the base electrode layer is taken as 100, the mass ratio of the alkaline earth metal in the glass present in the vicinity of the surface on the laminate side is 105 to 115.

[0084] (Item 8) In the multilayer ceramic capacitor according to any one of Items 1 to 7, the base electrode layer is a sintered layer of a conductive paste containing a glass composition. ２ O, Na ２ O, CaO, BaO and B ２ O ３ The glass composition contains B. ２ O ３ Li for ２ O, Na ２ The total mass ratio of O, CaO and BaO is 1.17 to 2.61.

[0085] REFERENCE SIGNS LIST 100 Multilayer ceramic capacitor, 110 Laminate, 111 First main surface, 112 Second main surface, 113 First side surface, 114 Second side surface, 115 First end surface, 116 Second end surface, 120 External electrode, 120A First external electrode, 120B Second external electrode, 121 Base electrode layer, 121A First base electrode layer, 121B Second base electrode layer, 122 Plating layer, 122A First upper plating layer, 122B First lower plating layer, 122C Second upper plating layer, 122D Second lower plating layer, 130 Dielectric layer, 140 Internal electrode layer, 140A First internal electrode layer, 140B Second internal electrode layer, 141A, 141B Counter electrode portion, 142A, 142B Lead electrode portion, 150 Glass, 151 conductive region, C inner layer portion, X1 first outer layer portion, X2 second outer layer portion, S1 first side margin portion, S2 second side margin portion, E1 first end margin portion, E2 second end margin portion, T stacking direction, W width direction, L length direction, T1 thickness direction.

Claims

1. A multilayer ceramic capacitor comprising an external electrode and a laminate including a plurality of laminated dielectric layers and a plurality of internal electrode layers, the external electrodes include a plating layer and a base electrode layer, the base electrode layer includes glass, the glass contains an alkaline earth metal; the base electrode layer has a mass ratio of the alkaline earth metal in the glass present in the vicinity of the surface on the plating layer side that is 90 or more and less than 100, when the mass ratio of the alkaline earth metal in the glass present in a central portion in a thickness direction is taken as 100; the base electrode layer is a sintered layer of a conductive paste containing a glass composition, the glass composition comprises Li 2 O, Na 2 O, CaO, BaO, and B 2 O 3 ; The multilayer ceramic capacitor comprises a glass composition having a mass ratio of the total of Li 2 O, Na 2 O, CaO and BaO to B 2 O 3 of 1.17 to 2.

61.

2. 2. The multilayer ceramic capacitor according to claim 1, wherein the base electrode layer has a mass ratio of the alkaline earth metal in the glass present in the vicinity of the surface on the plating layer side of 96 to 98.

3. The multilayer ceramic capacitor according to claim 2 , wherein the glass comprises borosilicate glass.

4. The multilayer ceramic capacitor according to claim 3 , wherein the glass further contains an alkali metal.

5. The multilayer ceramic capacitor according to claim 3 , wherein the glass further contains copper oxide.

6. 2. The multilayer ceramic capacitor according to claim 1, wherein the base electrode layer further contains at least one conductive component selected from the group consisting of copper, nickel, and a copper-nickel alloy.

7. 2. The multilayer ceramic capacitor according to claim 1, wherein, in the thickness direction of the base electrode layer, when a mass ratio of the alkaline earth metal in the glass present in a central portion is taken as 100, a mass ratio of the alkaline earth metal in the glass present in the vicinity of the surface on the laminate side is 105 or more and 115 or less.