Multilayer ceramic capacitors

Abstract

The purpose of the present invention is to provide a multilayer ceramic capacitor (1) that is resistant to cracking due to firing. The multilayer ceramic capacitor (1) comprises a stack (10) in which dielectric layers (20) and internal electrodes (30) are alternately layered. The stack (20) includes a first major surface and a second major surface that oppose each other in the stacking direction (T), a first side surface and a second side surface that oppose each other in a width direction (W) orthogonal to the stacking direction (T), and a first end surface and a second end surface that oppose each other in a length direction (L) orthogonal to the stacking direction (T) and to the width direction (W). External electrodes (40) connected to the internal electrodes (30) are provided on the first end surface and the second end surface of the stack (10). The internal electrodes (30) each include a main-opposing portion (301) and thin portions (302). The thickness of the thin portions (302) is less than the thickness of the main-opposing portion (301). The thin portions (302) extend from the ends of the main-opposing portion (301) in the width direction (W) to the first side surface or the second side surface.

Description

[Technical Field]

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

[0002] In recent years, there has been a demand for miniaturization of multilayer ceramic capacitors. When mechanical force is applied to such small multilayer ceramic capacitors, cracks may occur in the dielectric, causing short circuits between the internal electrodes. To address this issue, Patent Document 1 states: A multilayer ceramic capacitor having a plurality of first and second internal electrodes connected to first and second external electrodes, respectively, the sum of the length of the first internal electrode in the direction of the second external electrode and the length of the second lower surface external electrode in the direction of the first external electrode is shorter than the distance between the first and second external electrodes; and A multilayer ceramic capacitor has been proposed in which the sum of the length of the second internal electrode in the direction of the first external electrode and the length of the first lower surface external electrode in the direction of the second external electrode is shorter than the distance between the first and second external electrodes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-163311 Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 does not take into consideration cracks that occur during firing. Recently, there has been a demand for larger capacitance in multilayer ceramic capacitors. To meet this demand, efforts have been made to maximize the size of the internal electrodes contained in the laminate, resulting in the miniaturization of the dielectric layers covering the internal electrodes. Therefore, cracks may occur in the miniaturized dielectric layer covering the internal electrodes during firing, which may lead to a decrease in reliability such as moisture resistance. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a multilayer ceramic capacitor that is less susceptible to cracks caused by firing. [Means for solving the problem]

[0005] The multilayer ceramic capacitor according to the present invention comprises: a laminate in which dielectric layers and internal electrodes are alternately stacked, the laminate has a first main surface and a second main surface that face each other in the stacking direction, a first side surface and a second side surface that face each other in a width direction that is a direction perpendicular to the stacking direction, and a first end surface and a second end surface that face each other in a length direction that is a direction perpendicular to the stacking direction and the width direction; the laminate includes external electrodes connected to the internal electrodes on the first end surface and the second end surface, the internal electrode has a main opposing portion and a thin portion, the thickness of the thin-walled portion is thinner than the thickness of the main opposing portion, The thin portion is a multilayer ceramic capacitor that extends from an end of the main opposing portion in the width direction to the first side surface or the second side surface. [Effects of the Invention]

[0006] According to the present invention, such a multilayer ceramic capacitor can be easily provided. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective view showing a multilayer ceramic capacitor according to an embodiment of the present invention; [Figure 2] 2 is a cross-sectional view of the multilayer ceramic capacitor shown in FIG. 1 taken along line II. [Figure 3] 2 is a cross-sectional view taken along line II-II of the multilayer ceramic capacitor shown in FIG. [Figure 4]2 is a cross-sectional photograph corresponding to a part of a cross-sectional view taken along line II-II of the multilayer ceramic capacitor according to the embodiment. [Figure 5] FIG. 1 is a diagram showing the contents of an example and a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0008] An example of an embodiment of the present invention will be described below with reference to the accompanying drawings, in which the same or equivalent parts are designated by the same reference numerals.

[0009] <Overview of laminated structure> Fig. 1 is a perspective view showing a multilayer ceramic capacitor according to this embodiment, Fig. 2 is a cross-sectional view of the multilayer ceramic capacitor shown in Fig. 1 taken along line II, and Fig. 3 is a cross-sectional view of the multilayer ceramic capacitor shown in Fig. 1 taken along line II-II. The multilayer ceramic capacitor 1 shown in Figs. 1 to 3 includes a laminate 10 and external electrodes 40. The external electrodes 40 include a first external electrode 41 and a second external electrode 42.

[0010] <Direction definition> 1 to 3 show an XYZ Cartesian coordinate system. The X direction is the length direction L of the multilayer ceramic capacitor 1 and the laminate 10, the Y direction is the width direction W of the multilayer ceramic capacitor 1 and the laminate 10, and the Z direction is the lamination direction T of the multilayer ceramic capacitor 1 and the laminate 10. Therefore, the cross section shown in FIG. 2 is also referred to as the LT cross section, and the cross section shown in FIG. 3 is also referred to as the WT cross section. The length direction L, width direction W, and stacking direction T do not necessarily have to be perpendicular to each other, and may intersect each other.

[0011] <Laminate> As shown in FIG. 1, the laminate 10 has a substantially rectangular parallelepiped shape and has a first main surface TS1 and a second main surface TS2 facing in the stacking direction T, a first side surface WS1 and a second side surface WS2 facing in the width direction W, and a first end surface LS1 and a second end surface LS2 facing in the length direction L. It is preferable to round the corners and ridges of the laminate 10. A corner is a portion where three surfaces of the laminate 10 intersect, and a ridge is a portion where two surfaces of the laminate 10 intersect.

[0012] As shown in FIG. 2, the laminate 10 has a plurality of dielectric layers 20 and a plurality of internal electrodes 30 stacked in a stacking direction T. The internal electrode 30 includes a first internal electrode 31 connected to a first external electrode 41 and a second internal electrode 32 connected to a second external electrode 42 . The laminate 10 also has, in the stacking direction T, an inner layer portion 100 and two outer layer portions 110 arranged so as to sandwich the inner layer portion 100 therebetween.

[0013] <Inner layer> The inner layer portion 100 includes some of the plurality of dielectric layers 20 and a plurality of internal electrodes 30. In the inner layer portion 100, the plurality of internal electrodes 30 are arranged facing each other with the dielectric layer 20 interposed therebetween. The inner layer portion 100 is a portion that generates electrostatic capacitance and essentially functions as a capacitor.

[0014] <Outer layer> Of the two outer layer portions 110 described above, the outer layer portion 110 arranged on the first main surface TS1 side is the first outer layer portion 111, and the outer layer portion 110 arranged on the second main surface TS2 side is the second outer layer portion 112. Specifically, the first outer layer portion 111 is disposed between the first main surface TS1 and an internal electrode 30 that is closest to the first main surface TS1 among the multiple internal electrodes 30. On the other hand, the second outer layer portion 112 is disposed between the second main surface TS2 and an internal electrode 30 that is closest to the second main surface TS2 among the multiple internal electrodes 30. The first outer layer portion 111 and the second outer layer portion 112 do not include an internal electrode 30, and include the other dielectric layers 20 of the plurality of dielectric layers 20 excluding the dielectric layer 20 arranged in the internal layer portion 100. The first outer layer portion 111 and the second outer layer portion 112 function as protective layers for the internal layer portion 100.

[0015] <Length direction L> As shown in FIG. 2, the laminate 10 can be divided in the length direction L into a capacitance generating portion L30, a first end gap portion LG1, and a second end gap portion LG2.

[0016] <Capacitance generation section> The capacitance generating portion L30 is a portion where capacitance is generated by the internal electrodes 30 facing each other.

[0017] <End gap part> The first end gap LG1 is the portion between the capacitance generating portion L30 and the first end face LS1, while the second end gap LG2 is the portion between the capacitance generating portion L30 and the second end face LS2. The first end gap LG1 functions as an extraction electrode portion to the first end surface LS1 of the first internal electrode 31, and the second end gap LG2 functions as an extraction electrode portion to the second end surface LS2 of the second internal electrode 32. The first end gap LG1 and the second end gap LG2 are also referred to as L gaps.

[0018] <Main facing part and thin part of the internal electrode> 3, the internal electrode 30 has a main facing portion 301 and a thin portion 302. More specifically, both the first internal electrode 31 and the second internal electrode 32 have the main facing portion 301 and the thin portion 302. The main facing portion 301 is a portion that faces another internal electrode 30 in the stacking direction T with the dielectric layer 20 interposed therebetween, and that mainly generates capacitance. On the other hand, the thin portion 302 extends from the main opposing portion 301 and has a thickness thinner than that of the main opposing portion 301 . Specifically, the thin portion 302 is a peripheral portion of the internal electrode 30 in plan view, i.e., a portion located outside the main facing portion 301. The thickness of the thin portion 302 is 40% or less of the thickness of the main facing portion 301. Here, the plan view refers to the internal electrode 30 viewed from the lamination direction L. The thickness of the internal electrode 30 is measured by polishing the cross section of the laminate 10 to expose it, and measuring the length of the exposed internal electrode 30 in the stacking direction T using a scanning electron microscope, as described in the <Measurement Method> section below. More specifically, the thickness of the internal electrode 30 is the average value of the thicknesses of the ten layers of internal electrodes 30 adjacent in the stacking direction T at the central portion in the stacking direction T at the location where the thickness is desired to be determined. The thickness of the main facing portion 301 is measured by the above-mentioned measuring method at the center position of the internal electrode 30 in the length direction L and width direction W. That is, the thickness of the main facing portion 301 is the average value of the thicknesses of 10 layers of internal electrodes 30 adjacent in the stacking direction T at the center position of the internal electrode 30 in the length direction L and width direction W.

[0019] An end portion of the main opposing portion 301 is referred to as a main opposing portion end portion 301E. As shown in FIG. 3, the thin portions 302 extend from each of the two main opposing portion ends 301E toward the adjacent side surface WS.

[0020] <Division of width direction W> The division of the laminate 10 in the width direction W will be described with reference to FIG. The portions of the main opposing portions 301 of the internal electrodes 30 that face each other in the stacking direction T form capacitance generating portions W30. The portion between the capacitance generating portion W30 and the first side surface WS1 is the first side gap portion WG1, and the portion between the capacitance generating portion W30 and the second side surface WS2 is the second side gap portion WG2.

[0021] <Capacitance generation section> The capacitance generating portion W30 is a portion where capacitance is generated by the main opposing portions 301 of the internal electrodes 30 opposing each other.

[0022] <Side gap section> The first side gap WG1 and the second side gap WG2 do not include the internal electrode 30, but only include the dielectric layer 20. The first side gap WG1 and the second side gap WG2 function as protective layers for the internal electrode 30. The first side gap WG1 and the second side gap WG2 are also referred to as W gaps.

[0023] <Thin-walled overlapping section> A portion where the thin portions 302 of the internal electrodes 30 face each other in the stacking direction T is referred to as a thin portion overlapping portion W302. Here, the starting point of thin-walled portion 302 is referred to as thin-walled portion starting point 302S, and the ending point of thin-walled portion 302 is referred to as thin-walled portion ending point 302E. The starting point of thin-walled portion 302 is the point where thin-walled portion 302 and main opposing portion end 301E meet. On the other hand, the ending point of thin-walled portion 302 is the end of thin-walled portion 302 opposite the starting point, and is a point facing first side surface WS1 or second side surface WS2. The thin portion overlapping portions W302 extend from the two main opposing portion ends 301E, that is, from the thin portion starting points 302S to the respective thin portion ending points 302E, in accordance with the arrangement of the thin portion 302.

[0024] <Definition of length> Here, the length of the capacitance generating portion W30 in the width direction W is defined as W1, the length of the thin portion overlapping portion W302 is defined as W2, and the length of the side gap portion WG in the width direction W is defined as W3. In the following description, the thin-walled portion overlapping portion W302, the first side gap WG1, and the second side gap WG2 are assumed to have the same length on the first side face WS1 side and the second side face WS2 side, but the lengths on the first side face WS1 side and the second side face WS2 side may be different.

[0025] The thin portion 302 will be described in detail below. Fig. 4 shows an example of the thin portion 302. As shown in the thin portion overlapping portion W302 in Fig. 4, the thin portion 302 extends in a thread-like manner from the main opposing portion end portion 301E.

[0026] <Thickness of thin wall> The thickness of the thin-walled portion 302 will be described. The thickness of the thin portion 302 is thinner than the thickness of the main opposing portion 301. For example, the thickness of the thin portion 302 is 40% or less of the thickness of the main opposing portion 301. Preferably, the thickness of the thin portion 302 is 30% or less, more preferably 20% or less of the thickness of the main opposing portion 301.

[0027] <Effects> In the multilayer ceramic capacitor 1 of this embodiment, a thin portion 302 that is thinner than the main opposing portion 301 is provided. Therefore, it is possible to provide a multilayer ceramic capacitor that is less susceptible to cracks caused by firing. As explained above, due to the difference in properties between ceramic and metal, cracks may occur during sintering in the dielectric layers 20. Cracks are more likely to occur when the number of laminated internal electrodes 30 is large and the thickness of the dielectric layers 20 surrounding the internal electrodes 30 is thin. In this regard, the multilayer ceramic capacitor 1 of this embodiment is provided with a thin portion 302 that is thinner than the main opposing portion 301 . By arranging the thin portion near the end of the internal electrode 30, it is possible to control the shrinkage behavior of the dielectric layer 20 that covers the periphery. For example, stress may occur between the dielectric layer and the internal electrode during firing. The dielectric layer and the internal electrode are made of different materials, ceramic and metal, and the thermal shrinkage rates of ceramic and metal are different. Therefore, the degree of shrinkage during sintering may differ between the dielectric layer and the internal electrode. In this regard, the multilayer ceramic capacitor 1 of this embodiment can alleviate the stress caused by shrinkage, thereby suppressing the occurrence of cracks and structural defects that may later cause cracks. As described above, the multilayer ceramic capacitor 1 of this embodiment can provide a multilayer ceramic capacitor 1 that is less susceptible to cracks caused by firing.

[0028] <Length of thin-walled part> The length of the thin-walled portion 302 will be described. The thin portion 302 extends from the main opposing portion end 301E toward the first side surface WS1 or the second side surface WS2, but does not extend to contact the first side surface WS1 or the second side surface WS2. 3, the length W2 of the thin-walled portion 302 in the width direction W is 10% or more of the length W3 of the side gap portion WG. Preferably, the length W2 is 20% or more of the length W3, more preferably 30% or more, and even more preferably 40% or more. By setting the length W2 within the above range, it is possible to more reliably provide a multilayer ceramic capacitor 1 that is less susceptible to cracks caused by firing. The length of the thin walled portion 302 mentioned above means the average length of the plurality of thin walled portions 302. The average length can be the average value of ten adjacent thin walled portions 302, for example.

[0029] <Straightness of thin-walled parts> The linearity of the thin-walled portion 302 will now be described. 3 and 4, the thin portion 302 does not necessarily extend linearly in the width direction W. The thin portion 302 may be curved, for example, in the direction of the first main surface TS1. On the other hand, the main opposing portions 301 extend almost linearly in the width direction W. That is, the main opposing portions 301 have a higher linearity than the thin-walled portions 302. 3, the length of the thin portion 302 in the width direction W from the thin portion start point 302S to the thin portion end point 302E is defined as a. The length of the range of the internal electrode 30 in the stacking direction T, including the main opposing portion 301 and the thin portion 302, is defined as b. The length a is a value indicating the length of the thin portion 302 in the width direction W, and is the same value as the length W2 described above.

[0030] <Amount of bending> Here, length a / length b is the amount of bending. The amount of bending is preferably 0.5 or more and 9.0 or less, and more preferably 1.0 or more and 5.0 or less. If the amount of bending exceeds 9.0, the internal electrodes 30 may come into contact with other internal electrodes 30 adjacent in the stacking direction T, which may easily cause a short circuit. On the other hand, if it is less than 0.5, it becomes difficult to adequately control the shrinkage behavior of the dielectric layer 20 that covers the periphery of the internal electrode 30. As a result, it becomes difficult to adequately prevent cracks from occurring during firing. The length b can be set appropriately depending on the size of the multilayer ceramic capacitor 1. For example, the length b can be set to 10 μm.

[0031] <Continuity> Next, continuity will be explained. The continuity is the ratio of the length of the portion of the internal electrode 30 where the conductive material actually exists per unit length. 4, the conductive material that constitutes the internal electrode 30 is shown as conductive material 30M, and the dielectric material is shown as dielectric material 20M. 4, the conductive material 30M does not exist continuously in the internal electrode 30. It extends discontinuously, so to speak, with the dielectric material 20M sandwiched between the conductive material 30M. Therefore, the proportion of the conductive material 30M in the net length of the internal electrode 30 is defined as the continuity. As shown in FIG. 4, in the internal electrode 30, the continuity of the thin-walled portion 302 is lower than the continuity of the main opposing portion 301. In the main opposing portion 301, the conductive material 30M occupies the majority, whereas in the thin portion 302, the proportion of the dielectric material 20M is greater than that of the conductive material 30M.

[0032] <Effects> In the multilayer ceramic capacitor 1 of this embodiment, the continuity of the thin portions 302 is lower than the continuity of the main opposing portions 301 . This makes it easy to control the shrinkage behavior of the dielectric layer 20 that covers the periphery of the internal electrode 30. This effectively prevents cracks from occurring and structural defects that may later cause cracks to occur. The continuity of the internal electrode 30 can be evaluated as an average of a plurality of internal electrodes 30. For example, it can be evaluated as an average of 10 adjacent main opposing portions 301 or 10 adjacent thin portions 302.

[0033] <Method for forming thin-walled sections> The following describes a method for forming the thin portion 302. The method for manufacturing the entire multilayer ceramic capacitor will be described later. As a method for forming the thin portion 302, for example, when printing an electrode material on a dielectric sheet, there is a method in which a conductive material corresponding to the thin portion is also printed. Alternatively, a conductive material may be added to a dielectric paste for thickness correction, which is then applied to the laminate before sintering.

[0034] First, the former method of printing the electrode material at the same time as printing the electrode material will be described. For example, when printing the pattern of the internal electrode on the dielectric sheet for the inner layer portion 100, the pattern of the thin portion 302 is printed in addition to the pattern of the main opposing portion 301. The printing method is not particularly limited and may be screen printing, gravure printing, or the like. A printing plate is formed so that the electrodes included in the thin-walled portion 302 have the desired length and continuity. Using this plate, a conductive material is printed onto the dielectric sheet. Thereafter, firing and other processes are carried out based on the usual manufacturing method of a multilayer ceramic capacitor. As a result, a multilayer ceramic capacitor 1 having a thin portion 302 can be obtained.

[0035] Next, a method of adding a conductive material to a dielectric paste for thickness correction and applying the paste to the laminate before sintering will be described. When dielectric sheets on which internal electrode patterns are printed are laminated, the thickness of the laminate may differ between the areas where the internal electrodes overlap and the areas where no internal electrodes exist. For example, the thickness of the laminate before firing may be thinner in the portion corresponding to the first side gap WG1 than in the portion corresponding to the capacitance generating portion W30 shown in Fig. 3. In this case, the thickness of the laminate can be adjusted by applying a dielectric paste to the portion corresponding to the first side gap WG1. A conductive material is added to this dielectric paste. Then, the dielectric paste to which the conductive material has been added is applied to a thin portion of the laminate corresponding to the first side gap portion WG1. This first side gap portion WG1 corresponds to the portion where the thin-walled portion 302 is to be formed. The application can be performed by a printing method such as screen printing, etc. In this case, the application position, application amount, amount of conductive material added, etc. are adjusted so that the electrodes included in the thin-walled portion 302 have the desired length and continuity. Thereafter, firing and other processes are carried out based on the normal manufacturing method of a multilayer ceramic capacitor. As a result, a multilayer ceramic capacitor 1 having a thin portion 302 can be obtained.

[0036] In any of the above methods, the desired curvature can be imparted to the thin-walled portion 302 by adjusting the thickness distribution of the dielectric sheet and the amount of dielectric paste applied.

[0037] The materials of each part will be explained below. <Internal electrode material> The internal electrode 30 contains, for example, metal Ni as a main component. The internal electrode 30 may contain, as a main component, or as a component other than the main component, at least one selected from metals such as Cu, Ag, Pd, or Au, or alloys containing at least one of these metals, such as an Ag-Pd alloy. Furthermore, the internal electrode 30 may contain, as a component other than the main component, particles of a dielectric material having the same composition as the ceramic contained in the dielectric layer 20. In this specification, the main metal component is defined as the metal component with the highest mass percentage.

[0038] <Solid solution layer> In addition, when Ni is used as a first metal component, a solid solution layer (not shown) in which a second metal component different from the first metal component is dissolved may be provided at the interface with the dielectric layer 20 or the outer layer portion 110 on both sides of the internal electrode 30 in the stacking direction T. The solid solution layer includes a central solid solution layer (not shown) and an outer solid solution layer (not shown). The second metal component is preferably Sn, In, Ga, Zn, Bi, Pb, Fe, V, Y or Cu, and is particularly preferably Sn. In the following description, the second metal component is assumed to be Sn. The solid solution layer is a layer in which Sn atoms randomly substitute for Ni atoms within the Ni atomic arrangement structure while maintaining the Ni atomic arrangement structure. The thickness of the solid solution layer is preferably 1 nm or more and 20 nm or less.

[0039] The solid solution layer may be provided on both interfaces of the internal electrodes 30 in the stacking direction T, but is not limited thereto, and may be provided only on one interface of the internal electrodes 30 in the stacking direction T. The solid solution layer is provided on all the internal electrodes 30, but is not limited thereto, and may be provided only on some of the internal electrodes 30.

[0040] <Central solid solution layer> The central solid solution layer is provided at the interface between the internal electrode 30 and the dielectric layer 20 or the outer layer portion 110 in the central region in the length direction L and width direction W of the laminate 10. The central solid solution layer has a greater proportion of Sn dissolved in Ni than the outer solid solution layers. Here, the interface does not only refer to a boundary but also to a region that may include a part of the internal electrode 30 and the dielectric layer 20 or the outer layer portion 110. The central solid solution layer can be a region located about 10 μm inward from the end portions of the main opposing portion 301 in the length direction L and the end portions of the main opposing portion 301 in the width direction W. In the central solid solution layer, Sn is preferably dissolved in a molar amount of 0.008 to 0.025, preferably about 0.02, i.e., 2 mol%, relative to the total molar amount of Ni and Sn. The ratio of Sn to Ni is the average value obtained by measuring 10 points at the interface in the center in the stacking direction T, the center in the width direction W, and the center in the length direction L by TEM analysis.

[0041] <Outer solid solution layer> The outer solid solution layer is provided in a region surrounding the central solid solution layer in the main facing portion 301. That is, the outer solid solution layer is a region extending from the end portions of the main facing portion 301 in the length direction L and the end portions of the main facing portion 301 in the width direction W to a position approximately 10 μm inward. In the outer solid solution layer, Sn is preferably dissolved in a molar amount of 0.001 to 0.005, preferably about 0.005, ie, 0.5 mol %, relative to the total molar amount of Ni and Sn.

[0042] <Internal electrode thickness and number> The thickness of the internal electrodes 30 is not particularly limited, but may be, for example, 0.4 μm or more and 1.5 μm or less. The number of internal electrodes 30 is not particularly limited, but is preferably, for example, 20 or more and 1000 or less.

[0043] <Dielectric materials> The plurality of dielectric layers 20 are made of a dielectric material. The dielectric material may be, for example, a dielectric ceramic containing components such as BaTiO3, CaTiO3, SrTiO3, or CaZrO3. The dielectric material may also be one in which a secondary component such as a Mn compound, an Fe compound, a Cr compound, a Co compound, or a Ni compound is added to the above main component.

[0044] <Thickness and material of the dielectric layer> The thickness of the dielectric layer 20 is not particularly limited, but is preferably, for example, 0.5 μm or more and 3.0 μm or less. The number of dielectric layers 20 is not particularly limited, but is preferably, for example, 20 to 1000. The number of dielectric layers 20 is the total number of the dielectric layers 20 in the inner layer portion 100 and the outer layer portion 110.

[0045] <Laminate dimensions> The dimensions of the laminate 10 described above are not particularly limited, but it is preferable that, for example, the length in the longitudinal direction L is 1.55 mm or more and 1.65 mm or less, the width in the width direction W is 0.75 mm or more and 0.85 mm or less, and the thickness in the stacking direction T is 0.75 mm or more and 0.85 mm or less.

[0046] <External electrode> Next, the external electrode 40 will be described. The external electrodes 40 include a first external electrode 41 and a second external electrode 42 . The first external electrode 41 is disposed on the first end face LS1 of the laminate 10 and is connected to the first internal electrode 31. The first external electrode 41 may extend from the first end face LS1 to a portion of the first main face TS1 and a portion of the second main face TS2. Alternatively, the first external electrode 41 may extend from the first end face LS1 to a portion of the first side face WS1 and a portion of the second side face WS2. The second external electrode 42 is disposed on the second end face LS2 of the laminate 10 and is connected to the second internal electrode 32. The second external electrode 42 may extend from the second end face LS2 to a portion of the first main face TS1 and a portion of the second main face TS2. The second external electrode 42 may also extend from the second end face LS2 to a portion of the first side face WS1 and a portion of the second side face WS2. The first external electrode 41 has a first base electrode 415, a first inner plating layer 416, and a first surface plating layer 417, and the second external electrode 42 has a second base electrode 425, a second inner plating layer 426, and a second surface plating layer 427.

[0047] <Base electrode> The first base electrode 415 is disposed on the first end face LS1 of the laminate 10 and covers the first end face LS1 of the laminate 10. The first base electrode 415 may extend from the first end face LS1 to a portion of the first main surface TS1, a portion of the second main surface TS2, a portion of the first side surface WS1, and a portion of the second side surface WS2. The second base electrode 425 is disposed on the second end face LS2 of the laminate 10 and covers the second end face LS2 of the laminate 10. The second base electrode 425 may extend from the second end face LS2 to a portion of the first main surface TS1, a portion of the second main surface TS2, a portion of the first side surface WS1, and a portion of the second side surface WS2. The first base electrode 415 and the second base electrode 425 may be fired layers containing a metal and glass. The glass may include a glass component containing at least one selected from B, Si, Ba, Mg, Al, Li, etc. A specific example is borosilicate glass. The metal may include Cu as a main component. The metal may include at least one selected from metals such as Ni, Ag, Pd, or Au, or alloys such as Ag-Pd alloys, as a main component or as a component other than the main component.

[0048] The fired layer is a layer formed by applying a conductive paste containing metal and glass to the laminate by a dipping method and firing the layer. The fired layer may be fired after firing the internal electrodes or simultaneously with the internal electrodes. The fired layer may also be a multi-layer structure. Alternatively, the first base electrode 415 and the second base electrode 425 may be resin layers containing conductive particles and a thermosetting resin. The resin layers may be formed on the fired layer described above, or may be formed directly on the laminate without forming a fired layer. The resin layer is a layer formed by applying a conductive paste containing conductive particles and a thermosetting resin to the laminate by a coating method and then firing the layer. The resin layer may be fired after firing the internal electrodes or simultaneously with firing the internal electrodes. The resin layer may also be a multi-layered layer. The thickness of each of the first base electrode 415 and the second base electrode 425 as the fired layer or resin layer is not particularly limited, and may be 1 μm or more and 10 μm or less. Alternatively, the first base electrode 415 and the second base electrode 425 may be formed by a thin film forming method such as sputtering or vapor deposition, and may be a thin film layer of 1 μm or less on which metal particles are deposited.

[0049] <Inner plating layer> First inner plating layer 416 is disposed on first base electrode 415 and covers at least a portion of first base electrode 415. Second inner plating layer 426 is disposed on second base electrode 425 and covers at least a portion of second base electrode 425. First inner plating layer 416 and second inner plating layer 426 include at least one selected from metals such as Cu, Ni, Ag, Pd, or Au, or alloys such as Ag-Pd alloys.

[0050] <Surface plating layer> The first surface plating layer 417 is disposed on the first inner plating layer 416 and covers at least a portion of the first inner plating layer 416. The second surface plating layer 427 is disposed on the second inner plating layer 426 and covers at least a portion of the second inner plating layer 426. The first surface plating layer 417 and the second surface plating layer 427 contain a metal such as Sn, for example.

[0051] <Role of inner plating layer and surface plating layer> Preferably, first inner plating layer 416 and second inner plating layer 426 are Ni plating layers, and first top plating layer 417 and second top plating layer 427 are Sn plating layers. The Ni plating layer can prevent the base electrode from being eroded by solder when mounting ceramic electronic components, and the Sn plating layer improves the wettability of solder when mounting ceramic electronic components, facilitating mounting. In other words, the first inner plating layer 416 and the second inner plating layer 426 have lower solder wettability than the first surface plating layer 417 and the second surface plating layer 427.

[0052] <Thickness of plating layer> The thickness of first plating layers 416 and 417, which are made up of first inner plating layer 416 and first surface plating layer 417, is not particularly limited and may be 1 μm or more and 10 μm or less. The thickness of second plating layers 426 and 427, which are made up of second inner plating layer 426 and second surface plating layer 427, is not particularly limited and may be 1 μm or more and 10 μm or less. As a result, the maximum value of the total length in the longitudinal direction L of the laminate 10 and the two external electrodes 41 and 42 may be 1.75 mm or more and 1.85 mm or less.

[0053] <Measurement method> Next, the measurement methods will be explained in order. The thickness of the dielectric layer 20 and the electrodes can be measured, for example, by observing the LT cross section of the laminate exposed by polishing near the center in the width direction with a scanning electron microscope. Each value may be the average of measurements taken at multiple locations in the length direction, or may be the average of measurements taken at multiple locations in the stacking direction. In particular, the film thickness of the internal electrode 30 is evaluated based on the average within the above-mentioned measurement range. Similarly, the thickness of the laminate 10 can be measured by, for example, observing an LT cross section near the center in the width direction of the laminate exposed by polishing, or a WT cross section near the center in the length direction of the laminate exposed by polishing, using a scanning electron microscope. Each value may also be an average of measurements taken at multiple locations in the length direction or width direction. Similarly, the length of the laminate 10 can be measured by, for example, observing the LT cross section near the center in the width direction of the laminate exposed by polishing with a scanning electron microscope. Each value may also be the average value of measurements taken at multiple locations in the stacking direction. Similarly, the width of the laminate 10 can be measured by, for example, observing a WT cross section of the laminate exposed by polishing near the center in the longitudinal direction with a scanning electron microscope. Each value may also be an average value of measurements taken at multiple locations in the stacking direction.

[0054] <Manufacturing method> Next, an example of a general method for manufacturing the above-mentioned multilayer ceramic capacitor 1 will be described. First, a dielectric sheet for the dielectric layers 20 and a conductive paste for the internal electrodes 30 are prepared. The dielectric sheet and the conductive paste contain a binder and a solvent. Known materials can be used as the binder and the solvent. Next, a conductive paste is printed on the dielectric sheet in a predetermined pattern, for example, to form an internal electrode pattern on the dielectric sheet. The internal electrode pattern can be formed by screen printing, gravure printing, or the like. Next, a predetermined number of dielectric sheets for the second outer layer portion 112, on which no internal electrode pattern is printed, are laminated. On top of that, dielectric sheets for the inner layer portion 100 on which internal electrode patterns are printed are laminated in order. At this time, if necessary, a dielectric paste for thickness correction may be applied appropriately to positions corresponding to each side gap portion. Furthermore, a conductive material for forming the thin portion 302 may be added to the dielectric paste for thickness correction. A predetermined number of dielectric sheets for the first outer layer portion 111, on which no internal electrode pattern is printed, are laminated on top of the laminate, thereby producing a laminated sheet.

[0055] Next, the laminated sheet is pressed in the lamination direction using a means such as a hydrostatic press to produce a laminated block. Next, the laminated block is cut to a predetermined size to cut out laminated chips. At this time, the corners and ridges of the laminated chips are rounded by barrel polishing or the like. Next, the laminated chips are fired to produce the laminate 10. The firing temperature depends on the materials of the dielectric and internal electrodes, but is preferably 900°C or higher and 1400°C or lower. Next, the first end surface LS1 of the laminate 10 is immersed in a conductive paste, which is an electrode material for the base electrode, using a dipping method, to apply the conductive paste for the first base electrode 415 to the first end surface LS1. Similarly, the second end surface LS2 of the laminate 10 is immersed in a conductive paste, which is an electrode material for the base electrode, using a dipping method, to apply the conductive paste for the second base electrode 425 to the second end surface LS2. These conductive pastes are then fired to form the first base electrode 415 and the second base electrode 425, which are fired layers. The firing temperature is preferably 600°C or higher and 900°C or lower.

[0056] As described above, the first base electrode 415 and the second base electrode 425, which are resin layers, may be formed by applying a conductive paste containing conductive particles and a thermosetting resin using a coating method and then firing it, or the first base electrode 415 and the second base electrode 425, which are thin films, may be formed using a thin film formation method such as a sputtering method or a vapor deposition method. Thereafter, a first inner plating layer 416 is formed on the surface of the first base electrode 415, and a second inner plating layer 426 is formed on the surface of the second base electrode 425. Thereafter, a first outer plating layer 417 is formed on the surface of the first inner plating layer 416, and a second outer plating layer 427 is formed on the surface of the second inner plating layer 426. Through the above steps, the multilayer ceramic capacitor 1 described above is obtained.

[0057] <Example> An example and a comparative example will be described with reference to FIG. The following multilayer ceramic capacitors were fabricated as examples and comparative examples. Chip size: 1.6mm(L) x 0.8mm(W) x 0.8mm(T) Thickness of main facing part of internal electrode: 0.6 μm Number of internal electrodes: 500 Dielectric layer thickness: 0.8 μm Number of dielectric layers: 500 Thin part thickness: 0.2 μm

[0058] FIG. 5 shows examples and comparative examples. -Whether or not to apply dielectric paste to the position corresponding to the side gap for thickness correction The amount of bending of the internal electrode 30 (length a / b in FIG. 3) ·Presence or absence of thin-walled part 302 When the thin-walled portion 302 exists, the average thickness (thickness of the thin-walled portion / thickness of the main opposing portion) Average length (W2 / W3 in FIG. 3) when thin-walled portion 302 exists Quality evaluation results The following has been summarized.

[0059] The average thickness and average length were calculated by averaging the values ​​of 10 adjacent points. The quality was evaluated according to the following criteria:

[0060] Electrical characteristic failure rate: After firing, 100 chips were measured for insulation resistance (IR), and chips with LogIR<5 were counted as short-circuited. If one or more chips out of 100 were defective, they were classified as "bad." The rest were classified as "good."

[0061] Structural defect rate after firing: The appearance of 100 chips after firing was observed on six sides using a stereomicroscope to check for cracks around the outer layer, and chips with cracks in the outer layer were counted as defective chips. If one or more chips out of 100 were defective, they were classified as "bad." The rest were classified as "good."

[0062] As shown in Figure 5, regardless of whether or not a dielectric paste for thickness compensation was applied, chips without thin-walled sections exhibited poor electrical characteristics or structural defects after firing. In contrast, in the chips having thin portions, neither poor electrical characteristics nor structural defects after firing occurred.

[0063] The larger the chip size, for example, 1.6 × 0.8 mm or more, and the narrower the width of the side gap, for example, 75 μm or less, the more likely poor electrical characteristics or structural defects will occur after firing. In multilayer ceramic capacitors with such chip sizes, the effects of the configuration of this embodiment are likely to be more pronounced.

[0064] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and various changes and modifications are possible. [Explanation of symbols]

[0065] 1. Multilayer ceramic capacitors 10 Laminate 20 dielectric layer 20M Dielectric Material 30 Internal electrode 30M conductive material 301 Main opposing part 301E Main opposing end 302 Thin-walled section 302S Thin section start point 302E Thin-walled section end 31 First internal electrode 32 Second internal electrode 40 External electrode 100 Inner layer 110 Outer layer L30 Capacitance generator W30 Capacitance generating unit W302 Thin-walled overlapping part WG1 First side gap WG2 Second side gap L lengthwise T Stacking direction W width direction a) Width from the start point of the thin-walled part to the end point of the thin-walled part b Length of the internal electrode in the lamination direction

Claims

1. A multilayer ceramic capacitor, a laminate in which dielectric layers and internal electrodes are alternately stacked, The laminate has a first main surface and a second main surface that face each other in the stacking direction, a first side surface and a second side surface that face each other in a width direction that is a direction perpendicular to the stacking direction, and a first end surface and a second end surface that face each other in a length direction that is a direction perpendicular to the stacking direction and the width direction, the laminate includes external electrodes connected to the internal electrodes on the first end surface and the second end surface, the internal electrode has a main opposing portion and a thin portion, the thickness of the thin-walled portion is thinner than the thickness of the main opposing portion, the thin-walled portion extends from an end of the main opposing portion in the width direction to the first side surface or the second side surface, The continuity of the thin-walled portion is lower than the continuity of the main opposing portion, the thickness of the thin-walled portion is 40% or less of the thickness of the main opposing portion, The thin-walled portion has a length that is 10% or more of the length from the end portion to the side surface adjacent to the end portion. Multilayer ceramic capacitor.

2. The thickness of the thin-walled portion is 30% or less of the thickness of the main opposing portion. The multilayer ceramic capacitor according to claim 1 .

3. The thin-walled portion has a length that is 20% or more of the length from the end portion to the side surface adjacent to the end portion.

3. The multilayer ceramic capacitor according to claim 1.

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