Multilayer ceramic electronic component and circuit board

Abstract

To provide a multilayer ceramic electronic component capable of suppressing a crack of a ceramic element assembly caused by a solder, and a circuit board.SOLUTION: A multilayer ceramic electronic component comprises a ceramic element assembly and a pair of external electrodes. The ceramic element assembly includes: a first corner connecting a first principal surface, a first side face and an end face; a second corner connecting a second principal surface, the first side face and the end face; a third corner connecting the first principal surface, a second side face and the end face; a fourth corner connecting the second principal surface, the second side face and the end face; and a plurality of internal electrodes. The ceramic element assembly is configured in a substantially rectangular parallelepiped. Each of the pair of external electrodes includes a ground layer and a first conductive resin layer. The first conductive resin layer is disposed on the first side face while covering the first corner, includes an L-shaped first side face resin part extending from the first corner in two directions, and covers at least a portion of the ground layer.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a multilayer ceramic electronic component having an external electrode and a circuit board.

Background Art

[0002] Multilayer ceramic electronic components such as multilayer ceramic capacitors are widely used in in-vehicle devices due to the trend of electronic control of automobiles. For example, in in-vehicle devices, a circuit board on which a multilayer ceramic electronic component is mounted may be disposed in an environment where the temperature change is very large. When the circuit board undergoes a large temperature change, the substrate expands and contracts thermally, and bending stress may be generated in the multilayer ceramic electronic component as well. For example, Patent Document 1 discloses a multilayer ceramic electronic component having an external electrode having a conductive resin layer with high bending strength from the viewpoint of suppressing the generation of cracks caused by this bending stress.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Multilayer ceramic electronic components are generally mounted on a substrate using solder. The solder wets the external electrode in a molten state and then cools and solidifies. The solder shrinks during the solidification process and exerts stress on the ceramic body. When the solder stays in part, the stress caused by the solder may concentrate on the staying part. When a large stress is generated by the solder, even when a conductive resin is used for the external electrode, the influence of the stress cannot be suppressed, cracks may occur in the ceramic body, and the reliability of the multilayer ceramic electronic component may decrease.

[0005] In view of the above circumstances, an object of the present invention is to provide a multilayer ceramic electronic component and a circuit board that can suppress cracks in the ceramic body caused by solder. [Means for solving the problem]

[0006] To achieve the above object, a multilayer ceramic electronic component according to one embodiment of the present invention includes a ceramic body and a pair of external electrodes. The ceramic body has first and second main surfaces perpendicular to a first axis, a pair of end faces perpendicular to a second axis orthogonal to the first axis, first and second side surfaces perpendicular to a third axis orthogonal to the first axis and the second axis, a first corner connecting the first main surfaces, the first side surfaces, and the end surfaces, a second corner connecting the second main surface, the first side surfaces, and the end surfaces, a third corner connecting the first main surface, the second side surfaces, and the end surfaces, a fourth corner connecting the second main surface, the second side surfaces, and the end surfaces, and a plurality of internal electrodes stacked in the first axis direction or the third axis direction, and is configured in an approximately rectangular parallelepiped shape. Each of the pair of external electrodes has a base layer and a first conductive resin layer. The underlayer covers the end surface. The first conductive resin layer is disposed on the first side surface so as to cover the first corner portion. ta The first side surface resin portion covers at least a portion of the foundation layer. The first side resin part has an L-shaped inner edge extending in the first axial direction and the second axial direction along the first corner on the first side.

[0007] In the multilayer ceramic electronic component having the above configuration, the external electrodes have a first conductive resin layer, thereby providing high flexural strength to the external electrodes. Furthermore, the first conductive resin layer includes an L-shaped first side surface resin portion disposed on the first side surface, covering the first corner. This allows molten solder to be guided from the end surface toward the center of the first side surface along the L-shaped inner edge of the first side surface resin portion during mounting. This allows the solder to be dispersed over a wide area of the first side surface, reducing stress that may occur after the solder solidifies. Therefore, the above configuration can suppress cracks in the ceramic element body due to solder.

[0008] The pair of external electrodes are each disposed so as to cover the second corner portion on the first side surface ta It may have a second conductive resin layer that includes a second side surface resin portion and covers at least a part of the base layer. In this case, the second side resin part may have an L-shaped inner edge extending in the first axial direction and the second axial direction along the second corner on the first side. In this case, the second conductive resin layer may be spaced apart from the first conductive resin layer in the first axial direction. Thus, the external electrode may have a second conductive resin layer not only on the first main surface side but also on the second main surface side in addition to the first conductive resin layer on the first main surface side. Thereby, even when either the first main surface or the second main surface is mounted facing the substrate side, the effect of suppressing the solder stress by the L-shaped side surface resin portion can be obtained. Therefore, the convenience during mounting can be enhanced.

[0009] Further, the first conductive resin layer may be disposed so as to cover the first corner portion on the end surface, and may include an L-shaped first end surface resin portion that extends from the first corner portion in the first axial direction and the third axial direction. Thereby, also on the end surface side, the molten solder can be guided along the L-shaped inner edge portion of the first end surface resin portion. Therefore, the retention of the solder can be suppressed also on the end surface side, and the crack of the ceramic element due to the solder can be more reliably suppressed.

[0010] The pair of external electrodes are each disposed so as to cover the third corner portion on the second side surface, and further has a third conductive resin layer that includes an L-shaped third side surface resin portion that extends from the third corner portion in the first axial direction and the second axial direction and covers at least a part of the base layer, The third conductive resin layer may be spaced apart from the first conductive resin layer in the third axial direction. Thus, the external electrode may have a third conductive resin layer not only on the first side surface side but also on the second side surface side in addition to the first conductive resin layer on the first side surface side.

[0011] Furthermore, in this case, the first conductive resin layer is disposed to cover the first corner portion on the end face, and includes an L-shaped first end face resin portion extending from the first corner portion in the first axial direction and the third axial direction. The third conductive resin layer is disposed to cover the third corner portion on the end face, and includes an L-shaped third end face resin portion extending from the third corner portion in the first axial direction and the third axial direction. The third end face resin portion may be spaced apart from the first end face resin portion in the third axial direction. Thereby, solder retention can be suppressed on any of the end face, the first and second side faces, and cracks in the ceramic element due to solder can be more reliably suppressed.

[0012] For example, the base layer further has a side base portion disposed on the first side face, and the dimension of the side base portion in the second axial direction may be 50% or less of the dimension of the first side face resin portion in the second axial direction. Thereby, the end portion of the side base portion can be covered with the conductive resin layer. Therefore, generation of cracks due to the base layer having a lower flexural strength than the conductive resin layer can be more reliably suppressed.

[0013] For example, each of the pair of external electrodes may further have a plating layer covering the base layer and the first conductive resin layer. Thereby, mounting with solder becomes easy.

[0014] A circuit board according to an aspect of the present invention includes a multilayer ceramic electronic component and a mounting substrate having connection electrodes. The multilayer ceramic electronic component has a ceramic element and a pair of external electrodes. The ceramic body has first and second main surfaces perpendicular to a first axis, a pair of end faces perpendicular to a second axis orthogonal to the first axis, first and second side surfaces perpendicular to a third axis orthogonal to the first axis and the second axis, a first corner connecting the first main surfaces, the first side surfaces, and the end surfaces, a second corner connecting the second main surface, the first side surfaces, and the end surfaces, a third corner connecting the first main surface, the second side surfaces, and the end surfaces, a fourth corner connecting the second main surface, the second side surfaces, and the end surfaces, and a plurality of internal electrodes stacked in the first axis direction or the third axis direction, and is configured in an approximately rectangular parallelepiped shape. Each of the pair of external electrodes has a base layer and a first conductive resin layer. The underlayer covers the end surface. The first conductive resin layer is disposed on the first side surface so as to cover the first corner portion. ta The first side surface resin portion covers at least a portion of the foundation layer. The first side resin part has an L-shaped inner edge extending in the first axial direction and the second axial direction along the first corner on the first side. Effect of the Invention

[0015] As described above, the present invention can provide a multilayer ceramic electronic component and a circuit board that can suppress cracks in the ceramic body caused by solder. [Brief description of the drawings]

[0016]

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[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, X-axis, Y-axis, and Z-axis, which are mutually orthogonal, are shown as appropriate, and are common to all the drawings.

[0018] [Basic Structure of Multilayer Ceramic Capacitor 10] Figs. 1 to 3 are diagrams showing the multilayer ceramic capacitor 10 according to the first embodiment of the present invention. Fig. 1 is a perspective view of the multilayer ceramic capacitor 10. Fig. 2 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along the line A-A' of Fig. 1. Fig. 3 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along the line B-B' of Fig. 1.

[0019] The multilayer ceramic capacitor 10 includes a ceramic body 11, a first external electrode 13a, and a second external electrode 13b. The outer surface of the ceramic body 11 has first and second end faces E1, E2 perpendicular to the X axis, first and second side faces S1, S2 perpendicular to the Y axis, and first and second main faces M1, M2 perpendicular to the Z axis.

[0020] The ceramic body 11 is substantially rectangular parallelepiped and has eight corners. As shown in Figs. 4 and 5 to be described later, the corner connecting the first main face M1, the first side face S1, and the first or second end face E1, E2 is defined as the first corner 111. The corner connecting the second main face M2, the first side face S1, and the first or second end face E1, E2 is defined as the second corner 112. The corner connecting the first main face M1, the second side face S2, and the first or second end face E1, E2 is defined as the third corner 113. The corner connecting the second main face M2, the second side face S2, and the first or second end face E1, E2 is defined as the fourth corner 114. It is preferable that the ceramic body 11 is chamfered and each of the corners 111 to 114 is formed of a rounded curved surface.

[0021] In the multilayer ceramic capacitor 10, the first external electrode 13a covers the first end face E1 of the ceramic body 11, and the second external electrode 13b covers the second end face E2 of the ceramic body 11. The external electrodes 13a and 13b face each other in the X-axis direction with the ceramic body 11 interposed therebetween and function as terminals of the multilayer ceramic capacitor 10.

[0022] The external electrodes 13a and 13b extend inward in the X-axis direction along the main surfaces M1, M2 and the side surfaces S1, S2 from the end surfaces E1, E2 of the ceramic body 11, respectively. The first external electrode 13a covers the four corner portions 111 to 114 located on the first end surface E1 side of the ceramic body 11, and the second external electrode 13b covers the four corner portions 111 to 114 located on the second end surface E2 side of the ceramic body 11.

[0023] In this embodiment, the multilayer ceramic capacitor 10 is substantially symmetric with respect to the Y-Z plane that bisects it in the X-axis direction. Similarly, the multilayer ceramic capacitor 10 is substantially symmetric with respect to the X-Y plane that bisects it in the Z-axis direction, and the X-Z plane that bisects it in the Y-axis direction. These symmetries will be described below as the "symmetry of the multilayer ceramic capacitor 10".

[0024] The external electrodes 13a and 13b are formed of a material having high conductivity. Specifically, the external electrodes 13a and 13b can be formed of, for example, a metal or an alloy mainly composed of at least one element of Ni (nickel), Cu (copper), Pd (palladium), Ag (silver), and Sn (tin). The detailed configuration of the external electrodes 13a and 13b will be described later.

[0025] The ceramic body 11 is formed of dielectric ceramics. The ceramic body 11 has a plurality of first internal electrodes 12a and a plurality of second internal electrodes 12b covered with dielectric ceramics. The plurality of internal electrodes 12a and 12b are both in the form of sheets extending along the X-Y plane, and in the example shown in FIGS. 2 and 3, they are alternately arranged along the Z-axis direction.

[0026] In the ceramic body 11, an opposing region T is formed in which the internal electrodes 12a and 12b face each other in the Z-axis direction with a ceramic layer interposed therebetween. The first internal electrode 12a is drawn out from the opposing region T to the first end surface E1 and connected to the first external electrode 13a. The second internal electrode 12b is drawn out from the opposing region T to the second end surface E2 and connected to the second external electrode 13b.

[0027] With such a configuration, in the multilayer ceramic capacitor 10, when a voltage is applied between the first external electrode 13a and the second external electrode 13b, a voltage is applied to a plurality of ceramic layers in the opposing region T of the internal electrodes 12a and 12b. As a result, in the multilayer ceramic capacitor 10, charges corresponding to the voltage between the external electrodes 13a and 13b are stored.

[0028] In the ceramic body 11, a dielectric ceramic with a high dielectric constant is used to increase the capacitance of each ceramic layer between the internal electrodes 12a and 12b. The dielectric ceramic can be mainly composed of, for example, a ceramic material having a perovskite structure represented by the general formula ABO3. Note that the perovskite structure may contain ABO 3-α deviating from the stoichiometric composition. Examples of the ceramic material having a perovskite structure include materials containing barium (Ba) and titanium (Ti), typified by barium titanate (BaTiO3). Specifically, for example, Ba 1-x-y Ca x Sr y Ti 1-z Zr z O3 (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) can be mentioned.

[0029] Note that the dielectric ceramic may also be in a composition system such as strontium titanate (SrTiO3), calcium titanate (CaTiO3), magnesium titanate (MgTiO3), calcium zirconate (CaZrO3), calcium zirconate titanate (Ca(Zr,Ti)O3), barium zirconate (BaZrO3), titanium oxide (TiO2), etc.

[0030] [Details of the external electrodes 13a and 13b] In the multilayer ceramic capacitor 10, the external electrodes 13a and 13b each have an underlayer 14 and a first conductive resin layer 151. Further, in the present embodiment, the external electrodes 13a and 13b each have a second conductive resin layer 152 and a plating layer 16. In the following description, the first external electrode 13a on the first end face E1 side will be described. Based on the symmetry of the multilayer ceramic capacitor 10, the second external electrode 13b on the second end face E2 side is similarly configured.

[0031] The underlayer 14 covers the first end face E1. In the present embodiment, the underlayer 14 extends in the X-axis direction from the first end face E1 along the first and second main faces M1 and M2 and the first and second side faces S1 and S2. That is, the underlayer 14 includes an end face underlayer portion 14e disposed on the first end face E1, a pair of side face underlayer portions 14s respectively disposed on the first and second side faces S1 and S2, and a pair of main face underlayer portions 14m respectively disposed on the first and second main faces M1 and M2. The end face underlayer portion 14e, the pair of side face underlayer portions 14s, and the pair of main face underlayer portions 14m are formed continuously.

[0032] In the present embodiment, the underlayer 14 is configured as a sintered metal film obtained by baking a conductive metal paste. As an example, the underlayer can be mainly composed of any one of Ni, Cu, Pd, and Ag.

[0033] The first and second conductive resin layers 151 and 152 cover at least a part of the underlayer 14. In the present embodiment, the first conductive resin layer 151 covers the main face underlayer portion 14m on the first main face M1 side of the underlayer 14 and extends upward in the Z-axis direction along the pair of side face underlayer portions 14s and the end face underlayer portion 14e. Similarly, the second conductive resin layer 152 covers the main face underlayer portion 14m on the second main face M2 side of the underlayer 14 and extends downward in the Z-axis direction along the pair of side face underlayer portions 14s and the end face underlayer portion 14e. The second conductive resin layer 152 is spaced apart from the first conductive resin layer 151 in the Z-axis direction.

[0034] Specifically, the first conductive resin layer 151 includes a first main surface resin portion 151m that covers the first main surface M1, a pair of first side surface resin portions 151s that respectively cover the first and second side surfaces S1, and a first end surface resin portion 151e that covers the first end surface E1. The first main surface resin portion 151m, the pair of first side surface resin portions 151s, and the first end surface resin portion 151e are formed continuously.

[0035] Similarly, the second conductive resin layer 152 includes a second main surface resin portion 152m that covers the second main surface M2, a pair of second side surface resin portions 152s that respectively cover the first and second side surfaces S1, and a second end surface resin portion 152e that covers the first end surface E1. The second main surface resin portion 152m, the pair of second side surface resin portions 152s, and the second end surface resin portion 152e are formed continuously.

[0036] The conductive resin layers 151 and 152 contain, for example, a resin and a conductive material. As the resin, for example, a thermosetting resin is used. Examples of the thermosetting resin include a phenol resin, an acrylic resin, a silicone resin, an epoxy resin, and a polyimide resin. As the conductive material, for example, spherical or flat metal powder (conductive filler) is used. Examples of the metal powder include Ag powder, Cu powder, etc. In addition to the above, the conductive resin layers 151 and 152 may contain other components such as an organic solvent and a curing agent.

[0037] The plating layer 16 covers the base layer 14 and the conductive resin layers 151 and 152. The plating layer 16 is, for example, a film formed by a wet plating method on the base layer 14 and the conductive resin layers 151 and 152. The plating layer 16 can be formed into a single-layer or multi-layer structure having any one of Ni, Cu, Sn, Pd, and Ag as a main component.

[0038] 4 and 5 are side views showing the multilayer ceramic capacitor 10 in a state in which the plating layer 16 has been removed from the external electrodes 13a, 13b, with Fig. 4 being a view from the Y-axis direction and Fig. 5 being a view from the X-axis direction. Note that these figures show the configuration of the multilayer ceramic capacitor 10 as viewed from the first side surface S1 side and the first end face E1 side, respectively, but due to the symmetry of the multilayer ceramic capacitor 10, the configuration as viewed from the second side surface S2 side and the second end face E2 side is also the same.

[0039] As shown in these figures, the external electrodes 13a and 13b have conductive resin layers 151 and 152 with characteristic shapes in order to suppress the concentration of stress caused by solder during mounting.

[0040] 4, the first side surface resin portion 151s of the first conductive resin layer 151 is disposed on the first side surface S1 so as to cover the first corner portion 111, and has an L-shaped planar shape extending from the first corner portion 111 in the Z-axis direction and the X-axis direction. That is, the first side surface resin portion 151s has an L-shaped inner edge portion N1 along the first corner portion 111 that is positioned so as to overlap with the first side surface S1 in a plan view seen from the Y-axis direction. The inner edge portion N1 includes, for example, a first extending portion N11 extending in the Z-axis direction, a second extending portion N12 extending in the X-axis direction, and a curved portion N13 connecting the first extending portion N11 and the second extending portion N12.

[0041] Similarly, the second side surface resin part 152s of the second conductive resin layer 152 is arranged on the first side surface S1 so as to cover the second corner part 112, and has an L-shaped planar shape extending from the second corner part 112 in the Z-axis direction and the X-axis direction. In other words, the second side surface resin part 152s has an L-shaped inner edge part N2 that is positioned along the second corner part 112 and overlaps with the first side surface S1 in a plan view seen from the Y-axis direction. The second side surface resin part 152s is spaced apart in the Z-axis direction from the first side surface resin part 151s.

[0042] The planar shape of the first and second side surface resin parts 151s, 152s is considered to be L-shaped as long as it follows the L-shaped outline of the first and second corner parts 111, 112, even if it looks different from the letter "L" strictly speaking.

[0043] As shown in Fig. 5, the first end surface resin portion 151e of the first conductive resin layer 151 connects the pair of first side surface resin portions 151s. An inner edge portion N3 located on the center side in the Z-axis direction of the first end surface resin portion 151e is connected to the inner edge portion N1 of the first side surface resin portion 151s. In the example shown in Fig. 5, the inner edge portion N3 is configured in a substantially linear shape along the Y-axis direction. However, the shape of the inner edge portion N3 is not limited to this and may be, for example, a curved shape that is convex in the Z-axis direction.

[0044] Similarly, the second end surface resin portion 152e of the second conductive resin layer 152 connects the pair of second side surface resin portions 152s. The second end surface resin portion 152e is spaced apart from the first end surface resin portion 151e in the Z-axis direction.

[0045] The plating layer 16 is formed to cover the base layer 14 and the conductive resin layers 151 and 152. Therefore, the outline of the plating layer 16 is formed along the outline of the combined portion of the base layer 14 and the first and second conductive resin layers 151 and 152. The plating layer 16 is formed with a uniform thickness and has irregularities corresponding to the irregularities on the surfaces of the base layer 14 and the conductive resin layers 151 and 152. That is, the portions of the plating layer 16 on the conductive resin layers 151 and 152 protrude from the portions on the base layer 14. As a result, an L-shaped step Ds resulting from the shape of the inner edge portions N1 and N2 of the side surface resin portions 151s and 152s and a step De resulting from the shape of the inner edge portion N3 of the end surface resin portions 151e and 152e are formed on the surface of the plating layer 16 (see FIGS. 6A and 6B and 7).

[0046] 6A is a side view showing a manufacturing process of a circuit board 100 using the multilayer ceramic capacitor 10. The circuit board 100 has a mounting substrate 110 on which the multilayer ceramic capacitor 10 is mounted via solder H. The mounting substrate 110 has a base material 101 extending along the XY plane and connection electrodes 102 provided on the base material 101. The two connection electrodes 102 are arranged to correspond to the external electrodes 13a and 13b of the multilayer ceramic capacitor 10, respectively.

[0047] In the manufacturing process of the circuit board 100, first, solder H is placed on each of the connection electrodes 102 of the mounting board 110. The multilayer ceramic capacitor 10 is placed on the mounting board 110 with the first main surface M1 of the ceramic body 11 facing the mounting board 110 and the positions of the external electrodes 13 a, 13 b aligned with the positions on the connection electrodes 102.

[0048] The mounting substrate 110 on which the multilayer ceramic capacitor 10 is mounted is heated in a reflow furnace or the like to melt the solder H on the connection electrodes 102. As a result, the molten solder H wets and spreads along the surfaces of the connection electrodes 102 of the mounting substrate 110 and the external electrodes 13a, 13b of the multilayer ceramic capacitor 10.

[0049] Specifically, the solder H spreads between the connection electrode 102 and the external electrodes 13a and 13b, and further wets and rises upward in the Z-axis direction onto the external electrodes 13a and 13b. Then, the solder H is returned to room temperature and solidified, thereby obtaining a circuit board 100 in which the multilayer ceramic capacitor 10 is connected to the mounting board 110 via the solder H, as shown in FIG. 6B.

[0050] When the solder H solidifies, the solder H shrinks, which can cause stress in the ceramic body 11 via the external electrodes 13a and 13b. If the solder H is unevenly distributed, stress will be concentrated in that area, which can cause cracks in the ceramic body 11.

[0051] On the other hand, it is expected that the multilayer ceramic capacitor 10 having the external electrodes 13a, 13b including the conductive resin layers 151, 152 will be used in harsh environments where the mounting substrate 110 is repeatedly flexed and deformed due to temperature changes. In this case, if a large stress is generated by the solder H in addition to the flexed deformation of the mounting substrate 110, even the highly deformable conductive resin layers 151, 152 will not be able to absorb the stress, and cracks will easily occur in the ceramic body 11. For this reason, there is a demand for a multilayer ceramic capacitor 10 configured to more reliably suppress the concentration of stress caused by the solder H.

[0052] Therefore, in the present embodiment, the first conductive resin layer 151 has a first side resin portion 151s having an L-shaped planar shape. As a result, as shown in FIG. 7A, an L-shaped step Ds is formed on the surfaces of the external electrodes 13a and 13b.

[0053] First, the molten solder H wets the end faces E1 and E2 sides of the external electrodes 13a and 13b with a large electrode area in the Z-axis direction, and then easily spreads from the end faces E1 and E2 sides of the external electrodes 13a and 13b to the side faces S1 and S2 sides. In the present embodiment, the solder H that reaches the side faces S1 and S2 sides easily spreads from the end faces E1 and E2 sides toward the center side in the X-axis direction along the L-shaped step Ds, as shown by the arrows in FIG. 7A. That is, the solder H spreads over a wide range of the side faces S1 and S2 without staying on the end faces E1 and E2 sides of the external electrodes 13a and 13b.

[0054] In addition, by making the inner edge portion N1 of the first side resin portion 151s L-shaped, it is possible to sufficiently secure the length of the step Ds that can be an induction portion of the solder H. In addition, since the inner edge portion N1 includes a first extending portion N11 extending in the Z-axis direction, the solder H that reaches the side faces S1 and S2 sides can be guided downward in the Z-axis direction along the first extending portion N11. As a result, it becomes difficult for the solder H to return to the end faces E1 and E2 sides, and it becomes easy to be guided to the center side in the X-axis direction. Further, in the present embodiment, the curved portion N13 of the inner edge portion N1 is rounded and not angular. Thereby, it is possible to suppress the solder H from staying at the angular portion. As a result, the molten solder H can be smoothly and surely guided to the center side in the X-axis direction.

[0055] Therefore, in the above configuration, even when the amount of the solder H is large, the solder H can be widely dispersed to the vicinity of the end portion on the center side in the X-axis direction of the first conductive resin layer 151 without staying in part. As a result, when the solder H solidifies, the stress caused by the solder H is dispersed, and cracks in the ceramic element 11 are suppressed. As a result, the ceramic element 11 can maintain sufficient flexural strength and maintain moisture resistance reliability.

[0056] In this embodiment, the first conductive resin layer 151 has a first end face resin part 151e that is continuously formed from the first side face resin part 151s. A step is formed between the inner edge part N3 of the first end face resin part 151e and the base layer 14. That is, as shown in FIG. 7B, due to these steps, steps De that can be induction parts of the solder H are also formed on the surfaces of the end faces E1 and E2 sides of the external electrodes 13a and 13b. This step De is connected to the steps Ds on the side faces S1 and S2 sides.

[0057] As a result, the solder H that has spread upward in the Z-axis direction on the end faces E1 and E2 sides of the external electrodes 13a and 13b can easily spread in the Y-axis direction to both ends in the Y-axis direction along the step De, as shown by the arrow in FIG. 7B. Furthermore, the solder H that has reached both ends in the Y-axis direction of the step De can continuously spread along the step Ds and spread over the side faces S1 and S2 sides of the external electrodes 13a and 13b. Thus, with the above configuration, the solder H can be more smoothly induced from the end faces E1 and E2 sides of the external electrodes 13a and 13b to the side faces S1 and S2 sides, and the spread of the solder H can be promoted. Therefore, the concentration of stress caused by the solder H can be more effectively suppressed.

[0058] Furthermore, by providing the first and second conductive resin layers 151 and 152 on both the first main surface M1 side and the second main surface M2 side, both the mode of facing the first main surface M1 to the mounting substrate 110 and the mode of facing the second main surface M2 to the mounting substrate 110 can be adopted during mounting. Thereby, the degree of freedom in the posture of the multilayer ceramic capacitor 10 during mounting can be increased, and the convenience during mounting can be increased.

[0059] 4, the dimension d1 in the X-axis direction of the side surface foundation portion 14s may be smaller than the dimension d2 in the X-axis direction of the first side surface resin portion 151s. This allows the boundary between the ceramic body 11 and the end portion 14a (see FIG. 2) of the foundation layer 14 on the inner side in the X-axis direction. Stress tends to concentrate on the end portion 14a when the circuit board 100 is flexurally deformed, but covering the end portion 14a with the first side surface resin portion 151s, which has relatively high deformability, can alleviate the stress. This more reliably suppresses the occurrence of cracks in the ceramic body 11.

[0060] [Method of manufacturing the multilayer ceramic capacitor 10] Fig. 8 is a flowchart showing an example of a method for manufacturing the multilayer ceramic capacitor 10 according to this embodiment. Figs. 9 to 10F are diagrams showing the manufacturing process of the multilayer ceramic capacitor 10. The method for manufacturing the multilayer ceramic capacitor 10 will be described below along Fig. 8 with appropriate reference to Figs. 9 to 10F.

[0061] (Step S01: Ceramic body production) In step S01, an unsintered ceramic body 11 is produced. The unsintered ceramic body 11 is obtained by stacking multiple ceramic sheets in the Z-axis direction and thermocompression bonding them. By printing a conductive metal paste in a predetermined pattern on the ceramic sheets in advance, the internal electrodes 12a and 12b can be arranged.

[0062] The ceramic sheet is an unfired dielectric green sheet formed by shaping a ceramic slurry into a sheet shape. The ceramic sheet is formed into a sheet shape using, for example, a roll coater or a doctor blade. The components of the ceramic slurry are adjusted so as to obtain a ceramic body 11 with a predetermined composition.

[0063] (Step S02: Firing) In step S02, the unfired ceramic green body 11 obtained in step S01 is fired. As a result, the ceramic green body 11 is sintered, and the ceramic green body 11 shown in FIG. 9 is obtained. The firing of the ceramic green body 11 can be performed, for example, in a reducing atmosphere or in an atmosphere with a low oxygen partial pressure. The firing conditions of the ceramic green body 11 can be determined as appropriate.

[0064] (Step S03: External electrode formation) In step S03, external electrodes 13a and 13b are formed on the ceramic green body 11 obtained in step S02. As a result, the multilayer ceramic capacitor 10 shown in FIGS. 1 to 3 is completed. Step S03 includes four steps: step S31, step S32, step S33, and step S34.

[0065] (Step S31: Underlayer formation) In step S31, an underlayer 14 of the external electrodes 13a and 13b is formed on the ceramic green body 11. The underlayer 14 is formed, for example, by applying a conductive metal paste to the end face E1 and E2 sides and baking it.

[0066] The coating method is not particularly limited. For example, a dip method in which the end face E1 and E2 sides of the ceramic green body 11 are immersed in the conductive metal paste in the X-axis direction can be used. As a result, an underlayer 14 having a shape that wraps around from the end face E1 to the main faces M1, M2 and the side faces S1, S2 can be easily formed. Also, in this method, the dimension of the underlayer 14 (side underlayer portion 14s) in the X-axis direction can be adjusted by the depth of the conductive metal paste in the X-axis direction when the ceramic green body 11 is immersed.

[0067] Also, by applying the conductive metal paste of the underlayer 14 before step S02, the firing of the ceramic green body 11 in step S02 and the baking of the underlayer 14 in step S31 can be performed in a single heat treatment.

[0068] (Step S32: Uncured resin layer formation) In step S32, an uncured resin layer L that constitutes the first and second conductive resin layers 151 and 152 of the external electrodes 13a and 13b is formed on the ceramic green body 11 on which the base layer 14 is formed. To form the uncured resin layer L, an uncured resin paste P containing a conductive material is used.

[0069] Figs. 10A to 10F show the process of forming the uncured resin layer L on the ceramic green body 11 in step S32. First, as shown in Fig. 10A, the first main surface M1 of the ceramic green body 11 is immersed in the uncured resin paste P arranged at two locations with a gap therebetween. As a result, the uncured resin paste P adheres to the first main surface M1 of the ceramic green body 11, and an intermediate film La as a part of the uncured resin layer L is formed as shown in Fig. 10B.

[0070] At this time, by making the length of the uncured resin paste P in the Y-axis direction larger than the length of the first main surface M1 in the Y-axis direction, the intermediate film La can be continuously formed from the first side surface S1 side to the second side surface S2 side of the first main surface M1.

[0071] Then, similarly, as shown in Fig. 10C, by immersing the second main surface M2 of the ceramic green body 11 in the uncured resin paste P, an intermediate film La as a part of the second uncured resin layer L2 is also formed on the second main surface M2 of the ceramic green body 11. As a result, the intermediate film La is formed at four locations on the surface of the ceramic green body 11.

[0072] Next, as shown in Fig. 10D, a part of the first end face E1 side of the base layer 14 is immersed in the uncured resin paste P arranged at two locations with a gap therebetween. As a result, the uncured resin paste P adheres to the first end face E1 side of the base layer 14, and together with the uncured resin paste P that constitutes the intermediate film La, an L-shaped uncured resin layer L is formed as shown in Fig. 10E.

[0073] In this case, too, by making the length of the uncured resin paste P in the Y-axis direction greater than the length of the first end face E1 in the Y-axis direction, the uncured resin layer L can be formed continuously from the first side face S1 side of the first end face E1 to the second side face S2 side.

[0074] 10F, the second end face E2 of the ceramic body 11 is immersed in the uncured resin paste P, thereby forming an L-shaped uncured resin layer L on the second end face E2 side as well. As a result, uncured resin layers L are formed in four locations on the surface of the ceramic body 11.

[0075] (Step S33: Heat curing treatment) In step S33, the formed uncured resin layer L is cured by heat treatment. The heat treatment temperature can be, for example, 100 to 500°C. This heat treatment can be performed, for example, in a reducing atmosphere or a low oxygen partial pressure atmosphere. As a result, the uncured resin layer L is thermally cured, and the first and second conductive resin layers 151 and 152 are formed.

[0076] (Step S34: Plating layer formation) In step S34, a plated layer 16 is formed by wet plating on the base layer 14 and the conductive resin layers 151, 152 formed on the ceramic body 11. This completes the external electrodes 13a, 13b. Because the plated layer 16 is formed with a uniform thickness by wet plating, steps Ds, De resulting from the shapes of the conductive resin layers 151, 152 as described above are formed in the external electrodes 13a, 13b.

[0077] (Variation) The above-described manufacturing method can be modified in various ways as long as it can provide the configuration of the multilayer ceramic capacitor 10 of this embodiment. For example, the method for forming the external electrodes 13a, 13b is not limited to the above-described method as long as it can form the base layer 14 and the conductive resin layers 151, 152.

[0078] 10A to 10C can be made to contain a smaller amount of metal powder than the uncured resin paste P shown in FIGS. 10D to 10F. This reduces the amount of metal in the portions of the conductive resin layers 151, 152 (side surface resin portions 151s, 152s and main surface resin portions 151m, 152m) extending in the X-axis direction. This reduces the occurrence of defects in moisture resistance tests, such as the metal powder in the conductive resin layers 151, 152 diffusing over the ceramic body 11 and causing electrical conduction between the external electrodes 13a, 13b facing each other in the X-axis direction.

[0079] Second Embodiment The first and second external electrodes are not limited to the configuration described in the first embodiment above, and for example, the shape of the base layer can be changed.

[0080] 11 to 13 are diagrams showing a multilayer ceramic capacitor 20 according to a second embodiment of the present invention. Fig. 11 is a perspective view of the multilayer ceramic capacitor 20. Fig. 12 is a cross-sectional view of the multilayer ceramic capacitor 20 taken along line CC' in Fig. 11. Fig. 13 is a side view seen from the Y-axis direction, showing a state in which plating layers 26 have been removed from external electrodes 23a and 23b, which will be described later. The same components as those in the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.

[0081] The multilayer ceramic capacitor 20 according to this embodiment includes a ceramic body 11 similar to that of the first embodiment, but includes first and second external electrodes 23a, 23b having a different configuration from that of the first embodiment. Specifically, the external electrodes 23a, 23b have first and second conductive resin layers 151, 152 similar to those in the first embodiment, but each has an underlayer 24 with a different configuration from that in the first embodiment. Accordingly, the configuration of the plating layer 26 also differs from that of the plating layer 16 in the first embodiment. The multilayer ceramic capacitor 20 of this embodiment also has symmetry with respect to the X-axis, Y-axis, and Z-axis, similar to the first embodiment.

[0082] As in the first embodiment, the underlayer 24 includes an end surface underlayer 24e arranged on the first end surface E1, side surface underlayers 24s arranged on the first and second side surfaces S1 and S2, respectively, and main surface underlayers 24m arranged on the first and second main surfaces M1 and M2, respectively.

[0083] 13, the dimension d1 in the X-axis direction of the side surface foundation portion 24s may be 50% or less, or may be 30% or less, or may be 20% or less of the dimension d2 in the X-axis direction of the first side surface resin portion 151s. Note that, due to the symmetry of the multilayer ceramic capacitor 20 with respect to the X-axis, the dimension d1 of the foundation layer 24 may be 50% or less, or may be 30% or less, or may be 20% or less of the dimension in the X-axis direction of the second side surface resin portion 352s.

[0084] The above configuration makes it possible to sufficiently shorten the length in the X-axis direction of the base layer 24, which has lower flexural strength than the first and second conductive resin layers 151, 152. As a result, the end portion 24a in the X-axis direction of the base layer 24 can be covered by the first and second conductive resin layers 151, 152, which have high flexural strength, and in addition, the end portion 24a can be positioned outside in the X-axis direction (toward the end faces E1, E2) of the opposing region T (see FIG. 12) of the internal electrodes 12a, 12b.

[0085] The facing region T is a region where the internal electrodes 12a, 12b face each other in the Z-axis direction with the ceramic layers sandwiched therebetween, and is a region that contributes to capacitance formation. If a crack in the ceramic body 11 reaches the facing region T, electrical problems such as short circuits may occur, and the multilayer ceramic capacitor 10 may fail. With the above configuration, not only can cracks be prevented from forming at the boundary between the end 24a of the base layer 24 and the ceramic body 11, but also cracks can be more reliably prevented from extending from the base layer 24 to the facing region T of the internal electrodes 12a, 12b. Therefore, deterioration of moisture resistance and problems such as short circuits can be more effectively prevented.

[0086] Further, the plating layer 16 is formed so as to cover the base layer 24 and the conductive resin layers 151 and 152. Therefore, the contour of the plating layer 16 is formed along the contour of the combined portion of the base layer 24 and the conductive resin layers 151 and 152. As a result, the contour of the portion covering the side surfaces S1 and S2 of the plating layer 16 has an L-shaped configuration along the shapes of the first and second side surface resin portions 151s and 152s.

[0087] FIG. 14 is a side view showing a circuit board 200 using the multilayer ceramic capacitor 20. In the circuit board 200, similarly to the first embodiment, the multilayer ceramic capacitor 20 is connected to the connection electrode 102 of the mounting substrate 110 via the solder H.

[0088] As described above, the solder H melted during mounting spreads along the surface of the plating layer 26. In the present embodiment, since the first side surface resin portion 151s of the first conductive resin layer 151 and the plating layer 26 covering the same are configured in an L-shape, the solder H reaching the side surfaces S1 and S2 spreads in the central side in the X-axis direction along the L-shaped configuration. As a result, the solder H can be sufficiently dispersed up to the vicinity of the end portion on the central side in the X-axis direction of the first conductive resin layer 151. Therefore, when the solder H solidifies, the stress caused by the solder H is dispersed, and cracks in the ceramic element 11 are suppressed.

[0089] Further, the solder H covering the side surfaces S1 and S2 also has a substantially L-shaped solder inner edge portion Hn along the inner edge portion N1 of the first side surface resin portion 151s. That is, the solder inner edge portion Hn includes a first end portion Hn1 above in the Z-axis direction, a second end portion Hn2 on the central side in the X-axis direction, and an intermediate portion Hn3 curved in an L-shape therebetween. As a result, as shown using the following comparative example, the stress caused by the solder H covering the side surfaces S1 and S2 can be more effectively dispersed, and the occurrence of cracks can be more reliably suppressed.

[0090] FIG. 15A is a side view of the multilayer ceramic capacitor 20' according to the comparative example of the present embodiment as viewed from the Y-axis direction, and is a view showing a mode in which the plating layer is removed from the external electrodes 23'a and 23'b. The external electrodes 23'a and 23'b each include a base layer 14 similar to that of the present embodiment, and first and second conductive resin layers 151' and 152'. The conductive resin layers 151' and 152' include first and second side surface resin portions 151's and 152's, which include an inner edge portion N' that is curved convexly in the opposite direction to the corners 111 and 112.

[0091] FIG. 15B is a side view showing a circuit board 200' using the multilayer ceramic capacitor 20'. 15B, the solder H' covering the side surfaces S1 and S2 has a solder inner edge portion H'n shaped along the convex inner edge portion N'. The solder inner edge portion H'n includes a first end portion H'n1 on the upper side in the Z-axis direction, a second end portion H'n2 on the center side in the X-axis direction, and an intermediate portion H'n3 therebetween. When the solder H' solidifies, stress may occur between the inner edge portion H'n of the solder and the surface of the solder H' and / or the boundary between the solder H' and the connection electrode 102. The surface of the solder H' and the boundary between the solder H' and the connection electrode 102 are also referred to as the "periphery H'a of the solder H'."

[0092] Contraction of the solder H' can cause stress in the external electrodes 23'a, 23'b in a direction toward the peripheral edge H'a of the solder H' (see the arrows in the figure). For example, stress is generated in the first end H'n1 of the solder inner edge portion H'n along the X-axis direction toward the surface of the solder H'. Stress is generated in the second end H'n2 of the solder inner edge portion H'n along the Z-axis direction toward the connection electrode 102. Stress is generated in the middle portion H'n3 of the solder inner edge portion H'n diagonally downward in the Z-axis direction toward the surface of the solder H' and the connection electrode 102.

[0093] 15B, in the intermediate portion H'n3 of the comparative example, the distance to the peripheral portion H'a of the solder H' is greater than in the first and second end portions H'n1 and H'n2, and the amount of contraction of the solder H' between the intermediate portion H'n3 and the peripheral portion H'a increases. This makes it easier for stress to concentrate in the intermediate portion H'n3, and this stress can cause cracks in the ceramic body 11.

[0094] On the one hand, as shown in FIG. 14, in the circuit board 200 of the present embodiment, the inner edge portion Hn of the solder H covering the side surfaces S1 and S2 is curved in an L shape. As a result, the distance from the intermediate portion Hn3 to the peripheral edge portion Ha of the solder H is regulated, and the shrinkage amount of the solder H between the intermediate portion Hn3 and the peripheral edge portion Ha is suppressed. Therefore, as shown by the arrow in the figure, the difference in the magnitude of the stress generated in the first end portion Hn1, the second end portion Hn2, and the intermediate portion Hn3 becomes small, and the stress starting from the inner edge portion Hn of the solder is effectively dispersed. As a result, in the ceramic element 11, the generation of cracks due to the solder H is more reliably suppressed.

[0095] Furthermore, also in the present embodiment, the curved portion N13 of the inner edge portion N1 of the first side surface resin portion 151s has a rounded shape and is not angular. As a result, it is possible to suppress the excessive retention of the solder H at the angular portion and the concentration of stress, and more reliably disperse the stress starting from the inner edge portion Hn of the solder.

[0096] <Third Embodiment> In the above embodiments, the configuration in which each external electrode has two conductive resin layers has been described, but the present invention is not limited to this. For example, as described in the following third embodiment, each external electrode may have four conductive resin layers.

[0097] FIGS. 16 to 20 are views showing a multilayer ceramic capacitor 30 according to the third embodiment of the present invention. FIG. 16 is a perspective view of the multilayer ceramic capacitor 30. FIG. 17 is a cross-sectional view of the multilayer ceramic capacitor 30 taken along line D-D' of FIG. 16. FIG. 18 is a cross-sectional view of the multilayer ceramic capacitor 30 taken along line E-E' of FIG. 16. FIG. 19A is a side view seen from the Y-axis direction (the first side surface S1 side) showing a state in which the plating layer 36 is removed from the external electrodes 33a and 33b. FIG. 19B is a side view seen from the Y-axis direction (the second side surface S2 side) showing the same state as FIG. 19A. FIG. 20 is a side view seen from the X-axis direction showing a state in which the plating layer 36 is removed from the external electrodes 33a and 33b described later. Hereinafter, for the configurations similar to those of the first embodiment described above, the same reference numerals will be given and the description will be omitted. Furthermore, the multilayer ceramic capacitor 30 of this embodiment also has symmetry with respect to the X-axis, Y-axis, and Z-axis, similar to the first embodiment.

[0098] The multilayer ceramic capacitor 30 according to this embodiment includes a ceramic body 11 similar to that of the first embodiment, but includes first and second external electrodes 33a, 33b having a different configuration from that of the first embodiment. Specifically, the external electrodes 33a, 33b each have a base layer 14 with the same configuration as in the first embodiment, a conductive resin layer with a different configuration from that in the first embodiment, and a plating layer 36 that covers these. In addition to first and second conductive resin layers 351, 352, the external electrodes 33a, 33b each have a third conductive resin layer 353 and a fourth conductive resin layer 354. That is, the external electrodes 33a, 33b each have four conductive resin layers 351, 352, 353, and 354 that cover the four corners 111 to 114.

[0099] The first to fourth conductive resin layers 351 to 354 cover at least a part of the underlayer 14. In this embodiment, the first conductive resin layer 351 is formed to cover the first corner portion 111 and extend from the first corner portion 111 along the X-axis, Y-axis, and Z-axis directions. The second conductive resin layer 352 is formed to cover the second corner portion 112 and extend from the second corner portion 112 along the X-axis, Y-axis, and Z-axis directions. The second conductive resin layer 352 is spaced apart from the first conductive resin layer 351 in the Z-axis direction. The third conductive resin layer 353 is formed to cover the third corner portion 113 and extend along the X-axis, Y-axis, and Z-axis directions from the third corner portion 113. The third conductive resin layer 353 is spaced apart from the first conductive resin layer 351 in the Y-axis direction. The fourth conductive resin layer 353 is formed to cover the fourth corner portion 114 and extend from the fourth corner portion 114 along the X-axis, Y-axis, and Z-axis directions. The fourth conductive resin layer 354 is spaced apart from the third conductive resin layer 353 in the Z-axis direction and from the second conductive resin layer 352 in the Y-axis direction. In the following description, the configuration of the first external electrode 33a will be mainly described. Based on the symmetry of the multilayer ceramic capacitor 30, the second external electrode 33b has the same configuration.

[0100] As shown in FIG. 19A, the first side surface resin portion 351s of the first conductive resin layer 351 is disposed to cover the first corner portion 111 on the first side surface S1 and has an L-shaped planar shape extending in the Z-axis direction and the X-axis direction from the first corner portion 111. That is, the first side surface resin portion 351s is configured in the same manner as the first side surface resin portion 151s of the first embodiment.

[0101] On the other hand, as shown in FIG. 20, the first end surface resin portion 351e of the first conductive resin layer 351 is also disposed to cover the first corner portion 111 on the first end surface E1 and has an L-shaped planar shape extending in the Z-axis direction and the Y-axis direction from the first corner portion 111. The first end surface resin portion 351e does not reach the second side surface S2.

[0102] In the first main surface resin portion 351m of the first conductive resin layer 351, the dimension in the X-axis direction is substantially the same as that of the first side surface resin portion 351s, and the dimension in the Y-axis direction is substantially the same as that of the first end surface resin portion 351e. That is, the first main surface resin portion 351m has a substantially rectangular planar shape.

[0103] The second conductive resin layer 352 has a configuration symmetric with respect to the first conductive resin layer 351 in the Z-axis direction. That is, as shown in FIG. 19A, the second side surface resin portion 352s is disposed to cover the second corner portion 112 on the first side surface S1 and has an L-shaped planar shape extending in the Z-axis direction and the X-axis direction from the second corner portion 112. As shown in FIG. 20, the second end surface resin portion 352e is also disposed to cover the second corner portion 112 on the first end surface E1 and has an L-shaped planar shape extending in the Z-axis direction and the Y-axis direction from the second corner portion 112. The second main surface resin portion 352m has a substantially rectangular planar shape similar to the first main surface resin portion 351m.

[0104] The third conductive resin layer 353 has a configuration that is symmetric with respect to the first conductive resin layer 351 in the Y-axis direction. That is, as shown in FIG. 19B, the third side surface resin portion 353s of the third conductive resin layer 353 is disposed to cover the third corner portion 113 on the second side surface S2, and has an L-shaped planar shape extending from the third corner portion 113 in the Z-axis direction and the X-axis direction. As shown in FIG. 20, the third end surface resin portion 353e of the third conductive resin layer 353 is disposed to cover the third corner portion 113 on the first end surface E1, and has an L-shaped planar shape extending from the third corner portion 113 in the Z-axis direction and the Y-axis direction. The third main surface resin portion 353m of the third conductive resin layer 353 has a substantially rectangular planar shape, similar to the first main surface resin portion 351m.

[0105] The fourth conductive resin layer 354 has a configuration that is symmetric with respect to the third conductive resin layer 353 in the Z-axis direction. That is, as shown in FIG. 19B, the fourth side surface resin portion 354s of the fourth conductive resin layer 354 is disposed to cover the fourth corner portion 114 on the second side surface S2, and has an L-shaped planar shape extending from the fourth corner portion 114 in the Z-axis direction and the X-axis direction. As shown in FIG. 20, the fourth end surface resin portion 354e of the fourth conductive resin layer 354 is disposed to cover the fourth corner portion 114 on the first end surface E1, and has an L-shaped planar shape extending from the fourth corner portion 114 in the Z-axis direction and the Y-axis direction. The fourth main surface resin portion 354m of the fourth conductive resin layer 354 has a substantially rectangular planar shape, similar to the first main surface resin portion 351m.

[0106] The first to fourth conductive resin layers 351 to 354 of the present embodiment are formed by applying and curing an uncured resin paste P, similar to the first and second conductive resin layers 351 and 352 of the first embodiment. For example, in FIGS. 10A to C of step S32, the uncured resin paste P is added in a pair on the front side in the Y-axis direction and also arranged in a pair on the back side in the Y-axis direction, for a total of four locations. The arrangement of each uncured resin paste P in the Y-axis direction is adjusted in consideration of the lengths of the first to fourth main surface resin portions 351m to 354m in the Y-axis direction. Thereby, the intermediate film La is formed at a total of eight locations on the first main surface M1 side and the second main surface M2 side by using the method described in FIGS. 10A to C. 10D to 10F, in addition to a pair on the front side in the Y-axis direction, another pair is also placed on the rear side in the Y-axis direction, for a total of four locations. The placement of the uncured resin paste P in the Y-axis direction is adjusted taking into account the lengths of the short portions in the Y-axis direction of the first to fourth end face resin portions 351e to 354e. As a result, L-shaped uncured resin layers L are formed in a total of eight locations on the first end face E1 side and the second end face E2 side using the method described with reference to FIGS. This uncured resin layer L is cured in the same manner as in step S33, thereby forming the first to fourth conductive resin layers 351 to 354.

[0107] The multilayer ceramic capacitor 30 of this embodiment is also mounted on a mounting substrate 110 via solder H, similar to the circuit board 100 shown in FIG. 6B.

[0108] In the multilayer ceramic capacitor 30 configured as described above, the external electrodes 33a, 33b have first to fourth conductive resin layers 351-354, respectively, and each conductive resin layer 351-354 includes side surface resin portions 351s-354s having an L-shaped planar shape and end surface resin portions 351e-354e also having an L-shaped planar shape. As a result, when the capacitor is mounted on the mounting board 110 via solder H, the molten solder H wets and spreads along the inner edges of the L-shapes of the end surface resin portions 351e-354e and the side surface resin portions 351s-354s.

[0109] In particular, in this embodiment, the end surface resin portions 351e-354e are also formed in an L-shape, which increases the length of the guide portions for the solder H on the end surfaces E1, E2. This makes it possible to more reliably prevent uneven distribution of the solder H on the end surface E1, E2 side, even when the amount of solder H is large, and more reliably prevent cracks in the ceramic body 11.

[0110] Furthermore, in the multilayer ceramic capacitor 30 having the above configuration, although a conductive resin that tends to have a higher resistance value than general metal materials is used, an increase in ESR can be suppressed as described below.

[0111] FIG. 21 is a schematic side view seen from the X-axis direction showing the positional relationship between the first external electrode 33a viewed from the side of the first end face E1 shown in FIG. 20 and the end portion 12e in the X-axis direction of the internal electrode 12a exposed on the first end face E1.

[0112] As shown in the figure, the first end face E1 includes a lead-out region R where the end portions 12e of the internal electrodes 12a and 12b are exposed. The lead-out region R is defined as a region surrounding the outer edges of all the end portions 12e exposed from each of the end faces E1 and E2, and is assumed to include a ceramic layer between the end portions 12e. Note that due to the symmetry of the multilayer ceramic capacitor 30 with respect to the X-axis, the second end face E2 side also includes a lead-out region R where the end portion 12e of the internal electrode 12b in the X-axis direction is exposed.

[0113] In the present embodiment, in a plan view seen from the X-axis direction, the overlap between the first end face resin portion 351e and the lead-out region R becomes extremely small. In particular, as shown in FIG. 21, it is preferable that the first end face resin portion 351e does not overlap the lead-out region R in the plan view. Similarly, in a plan view seen from the X-axis direction, the overlaps between the second to fourth end face resin portions 352e to 354e and the lead-out region R are extremely small, and it is preferable that the second to fourth end face resin portions 352e to 354e do not overlap the lead-out region R. Specifically, the area of the overlapping portion between the first end face resin portion 351e and the lead-out region R in the plan view seen from the X-axis direction is preferably 10% or less of the area of the first end face resin portion 351e in the plan view.

[0114] Thereby, after mounting with the solder H, a wide current path that does not pass through the conductive resin layers 351 to 354 can be provided between the mounting substrate 110 and the internal electrodes 12a and 12b. Therefore, an increase in ESR due to the current passing through the conductive resin layers 351 to 354 can be suppressed.

[0115] [Modification Example 1] As shown in FIG. 22, the base layer 14 of the present embodiment may be changed to the same base layer 24 as in the second embodiment. 22 and 23 are diagrams showing a multilayer ceramic capacitor 40 according to a modified example of this embodiment. Fig. 22 is a perspective view of the multilayer ceramic capacitor 40. Fig. 23 is a side view, seen from the Y-axis direction, showing a state in which the plating layer has been removed from the external electrodes 43a and 43b. The external electrodes 43a, 43b of this modification have a base layer 24 similar to that of the second embodiment, first to fourth conductive resin layers 351 to 354 similar to those of the third embodiment, and a plating layer (not shown) covering these.

[0116] 23, in this modification as well, the dimension d1 in the X-axis direction of the side surface foundation portion 24s of the foundation layer 24 may be 50% or less, or may be 30% or less, or may be 20% or less, of the dimension d2 in the X-axis direction of the first side surface resin portion 351s. Note that, due to the symmetry of the multilayer ceramic capacitor 40 with respect to the X-axis, the dimension d1 of the foundation layer 24 may be 50% or less, or may be 30% or less, or may be 20% or less, of the dimension in the X-axis direction of the second to fourth side surface resin portions 352s to 354s.

[0117] As a result, in addition to the effects of suppressing uneven distribution of the solder H and suppressing an increase in ESR, as described in the third embodiment, the effects of suppressing cracks from extending to the opposing region T of the internal electrodes 12a, 12b and the stress dispersion effect of the L-shaped solder H, as described in the second embodiment, are exerted. Therefore, the reliability of the multilayer ceramic capacitor 40 can be further improved.

[0118] [Variation 2] The internal electrodes 12a and 12b may be alternately stacked along the Y-axis direction, which also provides the above-mentioned effects. 24 is a side view seen from the X-axis direction, showing a state in which the plating layer 36 has been removed from the external electrodes 33a, 33b when the lamination direction of the internal electrodes 12a, 12b of the multilayer ceramic capacitor 30 in accordance with the third embodiment is changed to the Y-axis direction. For the sake of explanation, the arrangement of the second internal electrode 12b that is not exposed from the first end face E1 is also shown by thin dashed lines in the drawing. As shown in the figure, also in this configuration, by making the overlap between the first to fourth end face resin portions 351e to 354e and the lead-out region R extremely small or eliminating it, the effect of suppressing the above-described increase in ESR can be obtained.

[0119] <Other Embodiments> As described above, the embodiments of the present invention have been explained. However, the present invention is not limited to only the above-described embodiments, and it goes without saying that various modifications can be made.

[0120] For example, in the first embodiment, the external electrodes 13a and 13b only need to have at least the first conductive resin layer 151, and do not necessarily need to have the second conductive resin layer 152 on the second main surface M2 side.

[0121] Also, in the third embodiment, an example in which the first to fourth end face resin portions 351e to 354e are configured in an L shape has been shown. However, the first to fourth end face resin portions 351e to 354e are not limited to this configuration, and may be, for example, substantially rectangular.

[0122] Alternatively, in the third embodiment, the first to fourth main surface resin portions 351m to 354m may further be configured in an L shape that covers the first to fourth corner portions 111 to 114.

[0123] Also, the multilayer ceramic capacitor according to the present embodiment is not limited to a two-terminal type, and can also be configured as a three-terminal type.

[0124] Furthermore, the present invention is applicable not only to multilayer ceramic capacitors but also to all multilayer ceramic electronic components having external electrodes. Examples of the multilayer ceramic electronic components to which the present invention can be applied include, in addition to multilayer ceramic capacitors, chip varistors, chip thermistors, multilayer inductors, and the like.

Explanation of Reference Numerals

[0125] 10, 20, 30, 40... Multilayer ceramic capacitors (multilayer ceramic electronic components) 11... Ceramic body 111...First corner, 112...Second corner, 113...Third corner, 114...Fourth corner 12a, 12b...Internal electrode 13a,13b,23a,23b,33a,33b,43a,43b...External electrode 14,24…base layer 151,351...first conductive resin layer 152,352...Second conductive resin layer 353…Third conductive resin layer 354...Fourth conductive resin layer 151s,351s…1st side resin part 152s,352s…Second side resin part 353s...Third side resin part 354s…4th side resin part 151e, 351e...First end resin part 152e, 352e…Second end resin part 353e...Third end resin part 354e...Fourth end resin part 16, 26, 36...plated layer 100, 200...Circuit board 110...Mounting board 102...Connection electrode

Claims

1. A substantially rectangular parallelepiped ceramic body having first and second main surfaces perpendicular to a first axis, a pair of end surfaces perpendicular to a second axis orthogonal to the first axis, first and second side surfaces perpendicular to a third axis orthogonal to the first axis and the second axis, a first corner connecting the first main surface, the first side surface and the end surface, a second corner connecting the second main surface, the first side surface and the end surface, a third corner connecting the first main surface, the second side surface and the end surface, a fourth corner connecting the second main surface, the second side surface and the end surface, and a plurality of internal electrodes laminated in the first axis direction or the third axis direction; An underlayer covering the end surface; A pair of external electrodes each having a first side resin portion disposed to cover the first corner on the first side surface and a first conductive resin layer covering at least a part of the underlayer; Comprising; The first side resin portion has an L-shaped inner edge extending in the first axis direction and the second axis direction along the first corner on the first side surface; A multilayer ceramic electronic component.

2. The multilayer ceramic electronic component according to Claim 1, wherein Each of the pair of external electrodes Has a second side resin portion disposed to cover the second corner on the first side surface and a second conductive resin layer covering at least a part of the underlayer; The second side resin portion has an L-shaped inner edge extending in the first axis direction and the second axis direction along the second corner on the first side surface; The second conductive resin layer is spaced apart from the first conductive resin layer in the first axis direction; A multilayer ceramic electronic component.

3. The multilayer ceramic electronic component according to Claim 1 or 2, wherein The first conductive resin layer Includes a first end surface resin portion disposed to cover the first corner on the end surface and extending in the first axis direction and the third axis direction from the first corner; A multilayer ceramic electronic component.

4. The multilayer ceramic electronic component according to any one of Claims 1 or 2, wherein Each of the pair of external electrodes Further has a third side resin portion disposed to cover the third corner on the second side surface and extending in the first axis direction and the second axis direction from the third corner, and a third conductive resin layer covering at least a part of the underlayer; The third conductive resin layer is spaced apart from the first conductive resin layer in the third axis direction; A multilayer ceramic electronic component.

5. The multilayer ceramic electronic component according to claim 4, wherein the first conductive resin layer is disposed to cover the first corner portion on the end face, and includes a first end face resin portion in an L shape extending from the first corner portion in the first axial direction and the third axial direction, the third conductive resin layer is disposed to cover the third corner portion on the end face, and includes a third end face resin portion in an L shape extending from the third corner portion in the first axial direction and the third axial direction, the third end face resin portion is spaced apart from the first end face resin portion in the third axial direction Multilayer ceramic electronic component.

6. A multilayer ceramic electronic component according to any one of claims 1 to 5, wherein the base layer further has a side base portion disposed on the first side surface, the dimension of the side base portion in the second axial direction is 50% or less of the dimension of the first side surface resin portion in the second axial direction Multilayer ceramic electronic component.

7. A multilayer ceramic electronic component according to any one of claims 1 to 6, wherein each of the pair of external electrodes further has a plating layer covering the base layer and the first conductive resin layer Multilayer ceramic electronic component.

8. A multilayer ceramic electronic component and a mounting substrate having connection electrodes, the multilayer ceramic electronic component has a substantially rectangular parallelepiped ceramic element having first and second main surfaces perpendicular to a first axis, a pair of end faces perpendicular to a second axis orthogonal to the first axis, first and second side surfaces perpendicular to a third axis orthogonal to the first axis and the second axis, a first corner connecting the first main surface, the first side surface and the end face, a second corner connecting the second main surface, the first side surface and the end face, a third corner connecting the first main surface, the second side surface and the end face, a fourth corner connecting the second main surface, the second side surface and the end face, and a plurality of internal electrodes stacked in the first axial direction or the third axial direction, a base layer covering the end face, a pair of external electrodes each having a first side surface resin portion disposed to cover the first corner portion on the first side surface and a first conductive resin layer covering at least a part of the base layer, and has the first side surface resin portion has an L-shaped inner edge extending along the first corner portion in the first axial direction and the second axial direction on the first side surface Circuit board.

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