Multilayer ceramic electronic components and circuit boards

Abstract

To provide a multilayer ceramic electronic component capable of suppressing peeling of an external electrode from a ceramic element assembly after mounting, and a circuit board.SOLUTION: A multilayer ceramic electronic component of the present invention comprises a ceramic element assembly and a pair of external electrodes. The ceramic element assembly includes a pair of principal surfaces vertical to a first axis, a pair of end faces vertical to a second axis, a pair of side faces vertical to a third axis and a plurality of internal electrodes drawn out to the pair of end faces and is configured in a substantially rectangular parallelepiped shape. The pair of external electrodes include end face covering parts covering the end faces and principal surface covering parts formed continuously from the end face covering parts and covering a part of the principal surfaces. The principal surface covering part includes: a conductive resin layer; and a first projection and a second projection formed based on the shape of the conductive resin layer. The first projection and the second projection are expanded toward a central side in a direction of the second axis and disposed while being separated in a direction of the third axis.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a multilayer ceramic electronic component and a circuit board. [Background technology]

[0002] Multilayer ceramic electronic components such as multilayer ceramic capacitors are widely used in in-vehicle devices due to the trend toward electronic control in automobiles. For example, in in-vehicle devices, a circuit board on which the multilayer ceramic electronic component is mounted may be placed in an environment with extremely large temperature changes. When the circuit board is subjected to large temperature changes, the thermal expansion and contraction of the board may cause stress in the multilayer ceramic electronic component. For example, Patent Document 1 discloses a multilayer ceramic electronic component equipped with external electrodes having a highly flexible conductive resin layer in order to suppress cracks caused by such stress. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-191880 Summary of the Invention [Problem to be solved by the invention]

[0004] Multilayer ceramic electronic components are generally mounted on a substrate using solder, with the lower surfaces of the external electrodes facing the substrate. When the substrate bends upward in a convex shape, stress is generated on the lower surfaces of the external electrodes in a direction that moves them away from the substrate. When this stress concentrates locally, even a highly flexible conductive resin layer cannot withstand the stress, and the external electrodes may peel off from the ceramic element body.

[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 prevent external electrodes from peeling off from the ceramic body after mounting. [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 a pair of main surfaces perpendicular to a first axis, a pair of end faces perpendicular to a second axis orthogonal to the first axis, a pair of side surfaces perpendicular to a third axis orthogonal to the first axis and the second axis, and a plurality of internal electrodes extended to the pair of end faces, and is configured in an approximately rectangular parallelepiped shape. The pair of external electrodes each have an end surface covering portion that covers the end surface, and a main surface covering portion that is formed continuously from the end surface covering portion and covers a part of the main surface. The main surface covering portion is The insulating layer covers the underlayer and extends further toward the center in the second axis direction than the underlayer. The conductive resin layer includes a first convex portion and a second convex portion formed based on the shape of the conductive resin layer. The first protrusion and the second protrusion each bulge toward the center in the second axial direction and are spaced apart from each other in the third axial direction. The main surface covering portion further has a minimum dimension in the second axis direction on the outer side of the first convex portion and the second convex portion in the third axis direction. The minimum dimension is substantially equal to the dimension of the underlayer in the second axis direction.

[0007] In the above configuration, the main surface covering portion that can face the substrate during mounting includes first and second convex portions formed based on the shape of the conductive resin layer. This allows for the stress to be distributed to the first and second convex portions even if the substrate is significantly warped due to temperature changes after mounting, causing significant stress in the main surface covering portion. This prevents the main surface covering portion from peeling off from the ceramic element body due to stress concentration.

[0008] For example, the second axis direction of the main surface covering portion of From the outer edge on the outside, in the first convex portion The aforementioned 2nd axis direction The most a first peak dimension in the second axis direction from the outer edge to the first apex located on the central side, and The above 2nd axis direction The mostThe second peak dimensions in the second axis direction up to the second apex located on the central side are respectively The aforementioned The minimum dimensions 1.5 It may be more than double. For example, the first peak dimension and the second peak dimension may each be 1 / 10 or more and 2 / 5 or less of the dimension of the multilayer ceramic electronic component in the second axis direction. This can enhance the effect of dispersing stress.

[0009] The first peak dimension may be greater than the second peak dimension. For example, the first peak dimension may be 1.1 times or more and 1.5 times or less than the second peak dimension. This ensures a sufficient first peak dimension of the first projections, thereby alleviating stress and improving adhesion to the ceramic body.

[0010] For example, the distance between the first apex and the second apex in the third axis direction may be not less than 1 / 5 and not more than 1 / 2 of the dimension of the monolithic ceramic electronic component in the third axis direction. This makes it possible to more reliably disperse stress generated in the first convex portion and the second convex portion, and also makes it difficult for stress to be generated outward in the third axis direction, thereby stabilizing the posture of the multilayer ceramic electronic component.

[0011] Furthermore, the pair of external electrodes each ,before and a plating layer that forms a surface layer of the end surface covering portion and the main surface covering portion. 。 before The first convex portion and the second convex portion may have a laminated structure of the conductive resin layer and the plating layer. This allows the conductive resin layer to be in direct contact with the ceramic body at the first and second convex portions. Therefore, the conductive resin layer can reduce the effect of stress on the ceramic body, suppressing cracks in the ceramic body. Furthermore, the adhesion of the first and second convex portions to the ceramic body can be improved.

[0012] A circuit board according to another aspect of the present invention includes a multilayer ceramic electronic component and a mounting substrate having connection electrodes. The multilayer ceramic electronic component includes a ceramic body and a pair of external electrodes. The ceramic body has a pair of main surfaces perpendicular to a first axis, a pair of end faces perpendicular to a second axis orthogonal to the first axis, a pair of side surfaces perpendicular to a third axis orthogonal to the first axis and the second axis, and a plurality of internal electrodes extended to the pair of end faces, and is configured in an approximately rectangular parallelepiped shape. The pair of external electrodes includes an end surface covering portion that covers the end surface, and a main surface covering portion that is formed continuously from the end surface covering portion and covers a part of the main surface. a base layer extending from the end surface covering portion to a part of the main surface covering portion; It has. The main surface covering portion is The insulating layer covers the underlayer and extends further toward the center in the second axis direction than the underlayer. The conductive resin layer includes a first convex portion and a second convex portion formed based on the shape of the conductive resin layer. The first protrusion and the second protrusion each bulge toward the center in the second axial direction and are spaced apart from each other in the third axial direction. The main surface covering portion further has a minimum dimension in the second axis direction on the outer side of the first convex portion and the second convex portion in the third axis direction. Furthermore, the main surface covering portion is disposed opposite the connection electrode. The minimum dimension is substantially equal to the dimension of the underlayer in the second axis direction. [Effects of the Invention]

[0013] As described above, the present invention can provide a multilayer ceramic electronic component and a circuit board that can prevent external electrodes from peeling off from the ceramic body after mounting. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a perspective view of 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 taken along line AA' in FIG. [Figure 3] 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line BB' in FIG. [Figure 4] FIG. 2 is a cross-sectional view of a circuit board on which the multilayer ceramic capacitor is mounted. [Figure 5] FIG. 4 is a cross-sectional view of the circuit board, showing a state in which bending has occurred in the circuit board. [Figure 6] FIG. 2 is a plan view of a multilayer ceramic capacitor according to a comparative example of the present embodiment, viewed from a first axis direction, illustrating the first main surface side. [Figure 7] 1 is a plan view of the multilayer ceramic capacitor of the present embodiment as viewed from a first axis direction, illustrating the first main surface side. [Figure 8] 8 is a plan view similar to FIG. 7, seen from the first axis direction of the multilayer ceramic capacitor, illustrating stress distribution. FIG. [Figure 9] 4 is a flowchart showing a method for manufacturing the multilayer ceramic capacitor. [Figure 10] FIG. 2 is a perspective view of the ceramic body obtained in step S02. [Figure 11A] FIG. 10 is a diagram showing step S31. [Figure 11B] FIG. 10 is a diagram showing step S31. [Figure 11C] FIG. 10 is a diagram showing step S31. [Figure 12] FIG. 10 is a diagram showing step S32. [Figure 13A] FIG. 10 is a diagram showing step S33. [Figure 13B] FIG. 10 is a diagram showing step S33. [Figure 13C] FIG. 10 is a diagram showing step S33. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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.

[0016] [Basic structure of multilayer ceramic capacitor 10] 1 to 3 are diagrams showing a multilayer ceramic capacitor 10 according to one 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 line A-A' in Fig. 1. Fig. 3 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along line B-B' in Fig. 1.

[0017] The multilayer ceramic capacitor 10 includes a ceramic body 11, a first external electrode 13a, and a second external electrode 13b. The surface of the ceramic body 11 has first and second end faces E1 and E2 perpendicular to the X-axis, first and second side faces S1 and S2 perpendicular to the Y-axis, and first and second main faces M1 and M2 perpendicular to the Z-axis. In other words, the ceramic body 11 has a substantially rectangular parallelepiped shape. It is preferable that the ceramic body 11 is chamfered, and the ridges connecting the respective faces are formed by rounded curves.

[0018] The maximum dimension of the multilayer ceramic capacitor 10 in the X-axis direction is defined as dimension L. The maximum dimension of the multilayer ceramic capacitor 10 in the Y-axis direction is defined as dimension W. The maximum dimension of the multilayer ceramic capacitor 10 in the Z-axis direction is defined as dimension T. These dimensions are not particularly limited, but may be within the following ranges, for example: Dimension L is, for example, 1.0 mm or more and 6.5 mm or less. Dimension W is, for example, 0.5 mm or more and 5.5 mm or less. Dimension T is, for example, 0.5 mm or more and 3.0 mm or less. The multilayer ceramic capacitor 10 has, for example, a size where dimension L is 3.2 mm, and dimensions W and T are 2.5 mm, a size where dimension L is 1.6 mm, and dimensions W and T are 0.8 mm, or a size where dimension L is 1.0 mm, and dimensions W and T are 0.5 mm.

[0019] 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 in between, and function as terminals of the multilayer ceramic capacitor 10.

[0020] The external electrodes 13a and 13b extend from the end faces E1 and E2 of the ceramic body 11 toward the center in the X-axis direction along the main faces M1 and M2 and the side faces S1 and S2, respectively. As a result, the cross sections of the external electrodes 13a and 13b parallel to the XZ plane and the XY plane shown in FIG. 2 are both U-shaped. The "center side in the X-axis direction" refers to the side closer to an imaginary YZ plane that divides the multilayer ceramic capacitor 10 into two equal parts in the X-axis direction. On the other hand, the "outside side in the X-axis direction" refers to the side away from the YZ plane. Similarly, the "center side in the Y-axis direction" refers to the side closer to an imaginary XZ plane that divides the multilayer ceramic capacitor 10 into two equal parts in the Y-axis direction. On the other hand, the "outside side in the Y-axis direction" refers to the side away from the XZ plane.

[0021] The ceramic body 11 is made of a dielectric ceramic. The ceramic body 11 has a plurality of first internal electrodes 12a and a plurality of second internal electrodes 12b covered with the dielectric ceramic. In the example shown in Figures 2 and 3, the plurality of internal electrodes 12a, 12b are both sheet-shaped and extend along the XY plane, and are arranged alternately along the Z-axis direction.

[0022] The ceramic body 11 has a facing region where the internal electrodes 12a and 12b face each other in the Z-axis direction with the ceramic layer sandwiched between them. The first internal electrode 12a extends from the facing region to the first end face E1 and is connected to the first external electrode 13a. The second internal electrode 12b extends from the facing region to the second end face E2 and is connected to the second external electrode 13b.

[0023] With this configuration, when a voltage is applied between the first external electrode 13a and the second external electrode 13b in the multilayer ceramic capacitor 10, the voltage is applied to the ceramic layers in the opposing regions of the internal electrodes 12a, 12b, causing the multilayer ceramic capacitor 10 to store a charge according to the voltage between the external electrodes 13a, 13b.

[0024] 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 may be mainly composed of a ceramic material having a perovskite structure represented by the general formula ABO3. The perovskite structure is formed by the ABO3 structure, which deviates from the stoichiometric composition. 3-α Examples of ceramic materials having a perovskite structure include materials containing barium (Ba) and titanium (Ti), such as barium titanate (BaTiO3). 1-x-y Ca x Sr y Ti 1-z Zr z O3 (0≦x≦1, 0≦y≦1, 0≦z≦1) is an example.

[0025] The dielectric ceramic may also be a composition system such as strontium titanate (SrTiO3), calcium titanate (CaTiO3), magnesium titanate (MgTiO3), calcium zirconate (CaZrO3), calcium titanate zirconate (Ca(Ti,Zr)O3), barium calcium titanate zirconate ((Ba,Ca)(Ti,Zr)O3), barium zirconate (BaZrO3), or titanium oxide (TiO2).

[0026] [Basic configuration of external electrodes 13a and 13b] The external shapes of the external electrodes 13a and 13b will be described with reference to Figures 2 and 3. In the following description of the external electrodes, the first external electrode 13a on the first end face E1 side will be mainly described, but the second external electrode 13b on the second end face E2 side is also configured in the same way.

[0027] The external electrode 13a has an end surface covering portion 13e that covers the end surface E1, a pair of main surface covering portions 13m that cover portions of the main surfaces M1 and M2, and a pair of side surface covering portions 13s that cover portions of the side surfaces S1 and S2. The main surface covering portions 13m are formed continuously from the end surface covering portion 13e and cover portions of the main surfaces M1 and M2. The side surface covering portions 13s are formed continuously from the end surface covering portion 13e and cover portions of the side surfaces S1 and S2.

[0028] Each of the external electrodes 13a and 13b has a laminated structure including a base layer 14, a conductive resin layer 15, and a plating layer 16.

[0029] The underlayer 14 is formed on the ceramic body 11 and is located at least on the end surface covering portion 13e. This electrically connects the underlayer 14 to the internal electrodes 12a, 12b. In this embodiment, the underlayer 14 extends from the end surface covering portion 13e to the main surface covering portion 13m and a portion of the side surface covering portion 13s. In this embodiment, the underlayer 14 is configured as a sintered metal film formed by baking a conductive metal paste. For example, the underlayer 14 may be primarily composed of one of nickel (Ni), copper (Cu), palladium (Pd), and silver (Ag). Alternatively, for example, the underlayer 14 may have a two-layer structure in which a plated layer of copper (Cu) or the like is formed on a sintered metal film primarily composed of nickel (Ni).

[0030] The conductive resin layer 15 covers the base layer 14, and in this embodiment, extends from the end surface covering portion 13e to the main surface covering portion 13m and the side surface covering portion 13s. Therefore, the main surface covering portion 13m includes the conductive resin layer 15. The conductive resin layer 15 covers the base layer 14 in the main surface covering portion 13m, and extends further toward the center in the X-axis direction than the base layer 14. In other words, in the region toward the center in the X-axis direction of the main surface covering portion 13m, the conductive resin layer 15 is in direct contact with the main surfaces M1, M2 of the ceramic body 11. Since the conductive resin layer 15 is based on a flexible resin, ,under It has higher flexibility and flexural strength than the base layer 14 and the plating layer 16.

[0031] The conductive resin layer 15 includes, for example, a resin and a conductive material. The resin may be, for example, a thermosetting resin. Examples of the thermosetting resin include phenolic resin, acrylic resin, silicone resin, epoxy resin, and polyimide resin. The conductive material may be, for example, a spherical or flat metal powder (conductive filler). Examples of the metal powder include Ag powder and Cu powder. In addition to the above, the conductive resin layer 15 may also include other components such as an organic solvent and a curing agent.

[0032] The plating layer 16 covers the conductive resin layer 15 and constitutes the surface layers of the end surface covering portion 13e, the main surface covering portion 13m, and the side surface covering portion 13s. The plating layer 16 is formed, for example, by a wet plating method on the conductive resin layer 15. The plating layer 16 has a single-layer or multi-layer structure containing at least one of Ni, Cu, Sn, Pd, and Ag as a main component.

[0033] With this configuration, the main surface covering portion 13m of this embodiment includes the highly flexible conductive resin layer 15. The multilayer ceramic capacitor 10 forms a circuit board 100 by, for example, soldering the external electrodes 13a and 13b to the mounting board 110 with the main surface covering portion 13m on the first main surface M1 side facing the mounting board 110.

[0034] [Configuration of circuit board 100] As shown in FIG. 4, the circuit board 100 includes the multilayer ceramic capacitor 10 and a mounting substrate 110.

[0035] The mounting substrate 110 has a substrate body 111 extending along the XY plane and connection electrodes 112 provided on the substrate body 111. The two connection electrodes 112 are arranged to correspond to the external electrodes 13a and 13b of the multilayer ceramic capacitor 10, respectively.

[0036] In the manufacturing process of the circuit board 100, first, solder H is placed on each connection electrode 112 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 13a, 13b aligned with the positions on the connection electrodes 112. As a result, the main surface covering portion 13m is placed opposite the connection electrodes 112.

[0037] 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 112. As a result, the molten solder H wets and spreads along the surfaces of the connection electrodes 112 of the mounting substrate 110 and the external electrodes 13a, 13b of the multilayer ceramic capacitor 10. The solder H cools and solidifies, connecting the multilayer ceramic capacitor 10 to the mounting substrate 110.

[0038] The manufactured circuit board 100 is mounted on an electronic device such as an in-vehicle device. When the circuit board 100 is used in an environment with large vibrations and temperature changes, such as an in-vehicle device, the mounting board 110 may be repeatedly flexed and deformed.

[0039] FIG. 5 is a schematic cross-sectional view showing a state in which the circuit board 100 is bent and deformed. As shown in the figure, circuit board 100 receives force F1, for example, in the upward Z-axis direction, as it deforms due to vibrations or temperature changes of the electronic device on which it is mounted. This causes circuit board 100 to bend and deform in a convex shape upward in the Z-axis direction, and generates stress F2 in circuit board 100 that, for example, flows outward in the X-axis direction along board body 111.

[0040] On the other hand, the multilayer ceramic capacitor 10 is less likely to bend than the mounting substrate 110. Therefore, the multilayer ceramic capacitor 10 connected to the mounting substrate 110 experiences a stress F3 directed toward the center in the X-axis direction.

[0041] Due to these stresses F2 and F3, a stress F4 is generated in a direction intersecting the Z-axis direction and the X-axis direction in the main surface covering portion 13m, which is the connection portion between the multilayer ceramic capacitor 10 and the mounting substrate 110. Since the conductive resin layer 15 of the external electrodes 13a and 13b is flexible, the conductive resin layer 15 of the main surface covering portion 13m can expand and contract in response to the stress F4. This can mitigate the effects of the stress F4.

[0042] On the other hand, in a harsh environment where temperature changes are extremely large and particularly large stress F4 is likely to occur, peeling of the external electrodes has occurred in conventional multilayer ceramic capacitors even when the external electrodes include conductive resin layers. Below, the configuration of the main surface coating portion of a conventional multilayer ceramic capacitor will be described as a comparative example to this embodiment.

[0043] 6 is a plan view of a multilayer ceramic capacitor 10′ according to a comparative example of this embodiment, viewed from the first main surface M1 side. The external electrodes 13a′, 13b′ of the multilayer ceramic capacitor 10′ have main surface covering portions 13m′ including conductive resin layers 15 (not shown in FIG. 6). In the external electrodes 13a' and 13b' of the multilayer ceramic capacitor 10', the inner edge N1' of the main surface covering portion 13m' on the central side in the X-axis direction has a shape that is curved convexly toward the central side in the X-axis direction. In other words, the main surface covering portion 13m' includes a single convex portion 131' that bulges in the X-axis direction.

[0044] In the manufacturing process of the multilayer ceramic capacitor 10, when the conductive resin layer 15 is formed by immersing the end faces E1, E2 in the resin paste (see step S33 described later), the resin paste tends to wet and rise on the main faces M1, M2 at the center in the Y-axis direction due to surface tension, resulting in the formation of a main face covering portion 13m' having the shape shown in FIG.

[0045] The inventors have found that under harsh environments, the protrusions 131' peel off from the ceramic body 11, causing poor connections between the external electrodes 13a', 13b' and the mounting substrate 110. This is thought to be because stress F4 is concentrated at the tops P' of the protrusions 131' to an extent that cannot be compensated for by the flexibility of the conductive resin layer 15.

[0046] Therefore, in this embodiment, from the viewpoint of effectively suppressing the concentration of such stress F4, the main surface covering portion 13m has the following configuration.

[0047] [Detailed configuration of external electrodes 13a and 13b] FIG. 7 is a plan view of the multilayer ceramic capacitor 10 as viewed from the first main surface M1 side. In this embodiment, the main surface covering portion 13m includes a first protrusion 131 and a second protrusion 132 that bulge out toward the center in the X-axis direction and are spaced apart in the Y-axis direction. In this embodiment, the main surface covering portion 13m on the second main surface M2 side is also configured in the same manner.

[0048] The first protrusion 131 includes a first apex P1. The first apex P1 is the portion of the first protrusion 131 that is located closest to the center in the X-axis direction. The second protrusion 132 includes a second apex P2. The second apex P2 is the portion of the second protrusion 132 that is located closest to the center in the X-axis direction. In addition, when the positions of the two first and second vertices P1 and P2 in the X-axis direction are different as shown in Figure 7, the convex portion including the vertex located closer to the center in the X-axis direction is defined as the "first convex portion 131."

[0049] In the principal surface covering portion 13m, an inner edge portion N1 on the center side in the X-axis direction has an uneven shape including two apexes P1 and P2 resulting from the first and second convex portions 131 and 132. In addition, in the principal surface covering portion 13m, the edge portion on the outer side in the X-axis direction is referred to as an outer edge portion N2.

[0050] The shapes of the first and second convex portions 131, 132 are determined by the shape of the conductive resin layer 15. That is, the conductive resin layer 15 has two convex portions (see FIG. 13C ), and the first and second convex portions 131, 132 are formed based on the shape of the conductive resin layer 15.

[0051] As shown in FIG. 8, in the multilayer ceramic capacitor 10 of this preferred embodiment, the main surface covering portion 13m has first and second protrusions 131 and 132, which allows the stress F4 to be distributed to the two vertices P1 and P2. This means that localized concentration of the stress F4 can be suppressed. This reduces the magnitude of the stress F4 generated at each of the vertices P1 and P2 compared to the magnitude of the stress F4 generated at the vertex P' in the comparative example. This prevents the main surface covering portion 13m from peeling off from the ceramic body 11 due to the stress F4. This prevents poor connection between the external electrodes 13a and 13b and the mounting substrate 110.

[0052] Furthermore, since the main surface covering portion 13m has the first and second protrusions 131, 132, the length of the conductive resin layer 15 in the X-axis direction can be sufficiently ensured. This allows the region in which flexibility can be exhibited to be expanded. Therefore, peeling of the main surface covering portion 13m from the ceramic body 11 can be more effectively suppressed.

[0053] 2, the first and second protrusions 131, 132 preferably have a laminated structure of a conductive resin layer 15 and a plating layer 16. That is, in the first and second protrusions 131, 132, the conductive resin layer 15 preferably contacts the ceramic body 11 directly without the need for a less flexible base layer 14. As a result, even if stress F4 occurs in the first and second protrusions 131, 132, the stress-relieving effect of the conductive resin layer 15 prevents the stress F4 from propagating to the ceramic body 11. This effectively prevents cracks in the ceramic body 11. Furthermore, the conductive resin layer 15 improves the adhesion of the first and second protrusions 131, 132 to the ceramic body 11, thereby more effectively preventing the first and second protrusions 131, 132 from peeling off from the ceramic body 11.

[0054] Furthermore, from the viewpoint of more reliably suppressing peeling of the main surface covering portion 13m, the dimensions of each portion of the main surface covering portion 13m can be set as follows: Note that, although Fig. 7 shows the dimensions of the main surface covering portion 13m of the second external electrode 13b, the main surface covering portion 13m of the first external electrode 13a can be configured in a similar manner.

[0055] 7, the dimension in the X-axis direction from the outer edge N2 on the outer side in the X-axis direction of the main surface covering portion 13m to the first apex P1 is defined as a first peak dimension D1, and the dimension in the X-axis direction from the outer edge N2 to the second apex P2 is defined as a second peak dimension D2. Furthermore, the dimension of the narrowest part of the principal surface covering portion 13m in the X-axis direction from the outer edge portion N2 to the inner edge portion N1 is defined as the minimum dimension D0 of the principal surface covering portion in the X-axis direction. The part of the principal surface covering portion 13m with the minimum dimension D0 may be located outside the first convex portion 131 and the second convex portion 132 in the Y-axis direction. Alternatively, this part may be a part between the first convex portion 131 and the second convex portion 132. The minimum dimension D0 is, for example, approximately equal to the dimension of the base layer 14 of the principal surface covering portion 13m in the X-axis direction.

[0056] For example, it is preferable that the first peak dimension D1 and the second peak dimension D2 are each 1.5 times or more the minimum dimension D0. This allows the first and second protrusions 131, 132 to be sufficiently expanded from the portion where the minimum dimension D0 is reached. Therefore, the first and second protrusions 131, 132 can reliably exert their stress dispersion effect.

[0057] This also ensures that the first protrusion 131 and the second protrusion 132 have sufficient lengths to exhibit flexibility against the stress F4. Additionally, it ensures sufficient adhesion of the main surface covering portion 13m to the ceramic body 11. Therefore, with the above configuration, peeling of the main surface covering portion 13m from the ceramic body 11 can be more effectively suppressed.

[0058] Furthermore, it is preferable that the first peak dimension D1 and the second peak dimension D2 are each four times or less the minimum dimension D0. This makes it possible to prevent the first and second external electrodes 13a, 13b from contacting each other and becoming electrically conductive. This also reduces the amount of conductive resin used, and simplifies manufacturing because the shapes of the first and second protrusions 131, 132 are not too steep.

[0059] Furthermore, the first peak dimension D1 and the second peak dimension D2 are preferably 1 / 10 or more and 2 / 5 or less of the dimension L of the multilayer ceramic capacitor 10 in the X-axis direction.

[0060] By making the first and second peak dimensions D1, D2 1 / 10 or more of the dimension L, it is possible to ensure that the first convex portions 131 and the second convex portions 132 have sufficient lengths to exhibit flexibility against the stress F4, and to ensure sufficient adhesion of the main surface covering portion 13m to the ceramic body 11. By making the first and second peak dimensions E1, E2 2 / 5 or less of the dimension L, it is possible to more reliably prevent the first and second external electrodes 13a, 13b from contacting each other and becoming conductive.

[0061] Furthermore, the first peak dimension D1 is preferably larger than the second peak dimension D2.

[0062] As described above, a longer peak dimension is advantageous in terms of alleviating stress F4 and improving adhesion to the ceramic body 11. Therefore, by forming the first and second protrusions 131, 132 with different first and second peak dimensions D1, D2 and lengthening the first peak dimension D1 of the first protrusion 131, the effects of alleviating stress F4 in the first protrusion 131 and improving adhesion to the ceramic body 11 can be further enhanced. Furthermore, compared to when both the first and second peak dimensions D1, D2 are lengthened, the risk of electrical continuity between the first and second external electrodes 13a, 13b can be reduced. Furthermore, the amount of conductive resin used can be reduced, and the shapes of both the first and second protrusions 131, 132 are not too steep, making manufacturing easier.

[0063] In particular, by making the first peak dimension D1 1.1 times or more the second peak dimension D2, the above-mentioned effects can be more reliably obtained. Furthermore, by making the first peak dimension D1 1.5 times or less the second peak dimension D2, the shape of the first protrusion 131 does not become too steep, which is advantageous from a manufacturing standpoint. Furthermore, the balance of the stress F4 generated in the first and second protrusions 131, 132 can be maintained, thereby reducing the risk of the multilayer ceramic capacitor 10 tipping over relative to the mounting substrate 110.

[0064] Furthermore, from the viewpoint of dispersing the stress F4 more reliably, it is preferable to space the first and second top portions P1 and P2 apart to some extent. For example, it is preferable that the distance Wp between the first and second top portions P1 and P2 in the Y-axis direction be between 1 / 5 and 1 / 2 of the dimension W of the multilayer ceramic capacitor 10 in the Y-axis direction.

[0065] By setting the separation distance Wp to be 1 / 5 or more of the dimension W, it is possible to prevent the stress F4 from concentrating at a nearby position, thereby more reliably achieving the effect of dispersing the stress F4 and preventing peeling of the main surface covering portion 13m. Setting the separation distance Wp to ½ or less of the dimension W can prevent the first and second protrusions 131, 132 from being positioned outward in the Y-axis direction. This makes it difficult for the stress F4 to be biased outward in the Y-axis direction, thereby reducing the risk of the multilayer ceramic capacitor 10 tipping over due to the stress F4 generated in the first and second protrusions 131, 132. This allows the circuit board 100 to maintain a stable mounting state.

[0066] [Method of manufacturing the multilayer ceramic capacitor 10] Fig. 9 is a flowchart showing an example of a method for manufacturing the multilayer ceramic capacitor 10 according to this embodiment. Figs. 10 to 13C are views 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. 9 with appropriate reference to Figs. 10 to 13C.

[0067] (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.

[0068] 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.

[0069] (Step S02: Firing) In step S02, the green ceramic body 11 obtained in step S01 is fired. This sinters the ceramic body 11, resulting in the ceramic body 11 shown in FIG. 10. The ceramic body 11 can be fired, for example, in a reducing atmosphere or a low-oxygen partial pressure atmosphere. The firing conditions for the ceramic body 11 can be determined as appropriate.

[0070] (Step S03: Forming external electrodes) In step S03, external electrodes 13a, 13b are formed on the ceramic body 11 obtained in step S02, thereby completing the multilayer ceramic capacitor 10 shown in Figures 1 to 3. Step S03 includes five processes: step S31, step S32, step S33, step S34, and step S35.

[0071] (Step S31: Formation of base layer) In step S31, the base layer 14 for the external electrodes 13a, 13b is formed on the ceramic body 11. The base layer 14 is formed, for example, by applying a conductive metal paste Ps1 containing Ni or Cu as a main component to the end faces E1, E2 and baking it.

[0072] 11A to 11C show the process of forming a base layer 14u made of conductive metal paste Ps1 on the ceramic body 11 in step S31. First, as shown in FIG. 11A, the ceramic body 11 is immersed in the conductive metal paste Ps1 from the first end face E1 side, and the conductive metal paste Ps1 is adhered to the ceramic body 11.

[0073] As a result, an unsintered base layer 14u is formed that covers the first end face E1 side of the ceramic body 11, as shown in FIG. 11B.

[0074] Similarly, as shown in FIG. 11C, by immersing the ceramic body 11 from the second end face E2 side into the conductive metal paste Ps1, an unsintered base layer 14u is formed on the second end face E2 side as well as on the first end face E1 side.

[0075] The immersion conditions in step S31 can be determined as appropriate. For example, the depth to which the ceramic body 11 is immersed in the conductive metal paste Ps1 can be set to a depth corresponding to the dimension in the X-axis direction of the base layer 14 after baking. After immersion, the base layer 14u can be dried under predetermined conditions.

[0076] Next, the unfired base layer 14u formed on the ceramic body 11 is baked by heat treatment. As a result, the base layer 14, which is a sintered film, is formed on the ceramic body 11. Note that by forming the base layer 14u in step S31 before step S02, the firing of the ceramic body 11 in step S02 and the baking of the base layer 14u in step S31 can be performed in a single heat treatment.

[0077] (Step S32: Water-repellent coating) In step S32, a water-repellent material is applied to the main surfaces M1 and M2 of the ceramic body 11 on which the underlayer 14 is formed. The water-repellent material may be, for example, a material containing a water-repellent component such as a fluorine compound or a silicon compound. This allows the wetting of the conductive resin paste to be controlled in the next step S33, in which the uncured resin layer is formed, and the first and second protrusions 131 and 132 can be formed.

[0078] In this step, first, the ceramic body 11 on which the underlayer 14 has been formed is masked so as to expose the area to be coated with the water-repellent material. Next, a water-repellent material is applied to the area exposed from the mask. The method for applying the water-repellent material is not particularly limited, and for example, spraying, sputtering, dipping, etc. can be used. Alternatively, if the water-repellent material contains a silicon-based component, it can be applied by contacting a heated silicon chip with the area exposed from the mask. The mask is then removed to obtain the ceramic body 11 having the water-repellent material applied to the first main surface M1. The water-repellent material can also be applied to the second main surface M2 in the same manner.

[0079] FIG. 12 is a diagram schematically illustrating a water-repellent region Q on the first main surface M1 where the water-repellent material is applied. The water-repellent region Q is set as a strip-shaped region along the X-axis direction in the center of the first main surface M1 in the Y-axis direction. The width of the water-repellent region Q in the Y-axis direction is set to be approximately 0.3 to 1 times the separation distance Wp between the peaks P1 and P2. The side edge Qs in the Y-axis direction of the water-repellent region Q is positioned to pass inside the peaks P1 and P2 of the first and second protrusions 131 and 132 in the Y-axis direction after manufacture. The length of the water-repellent region Q in the X-axis direction may be any length that reaches the recess between the first and second protrusions 131 and 132 after manufacture, and may, for example, extend over the entire length of the first main surface M1 in the X-axis direction, including the underlayer 14. The water-repellent area Q can also be formed on the second main surface M2 side in the same manner.

[0080] (Step S33: Forming an uncured resin layer) In step S33, an uncured resin layer 15u that constitutes the conductive resin layer 15 is formed on the ceramic body 11 on which the base layer 14 and the water-repellent region Q have been formed. To form the uncured resin layer 15u, an uncured resin paste Ps2 containing a conductive material is used. The uncured resin paste Ps2 contains, for example, a paste-like thermosetting resin and a metal powder. The uncured resin paste Ps2 may also contain other components such as an organic solvent and a curing agent.

[0081] 13A to 13C show the process of forming the uncured resin layer 15u on the ceramic body 11 in step S33. First, as shown in FIG. 13A, the ceramic body 11 is immersed in the uncured resin paste Ps2 from the first end face E1 side to a position covering the base layer 14, and the uncured resin paste Ps2 is adhered to the ceramic body 11.

[0082] The deposited uncured resin paste Ps2 wets and rises upward in the X-axis direction from the first end face E1 onto the principal faces M1 and M2 and the side faces S1 and S2. In particular, the uncured resin paste Ps2 tends to wet and rise more in the center in the Y-axis direction due to surface tension. In this embodiment, a water-repellent region Q is formed in the center of the principal faces M1 and M2 in the Y-axis direction. Therefore, the uncured resin paste Ps2 does not wet and rise more in the water-repellent region Q but wets and rises more along its side edges in the Y-axis direction. As a result, as shown in FIG. 13B , an uncured resin layer 15u is formed on the principal faces M1 and M2, extending from the first end face E1 along the principal faces M1 and M2 and the side faces S1 and S2, and including the first protrusions 151u and the second protrusions 152u.

[0083] 13C, the ceramic body 11 is immersed in the uncured resin paste Ps2 from the second end face E2 side to a position that covers the base layer 14. As a result, an uncured resin layer 15u including a first convex portion 151u and a second convex portion 152u is formed on the second end face E2 side as well, similar to the first end face E1 side.

[0084] In this method, the positions of the corresponding peaks P1 and P2 can be adjusted by adjusting the position of the side edge Qs of the water-repellent region Q. For example, if the side edge Qs of the water-repellent region Q is shifted outward in the Y-axis direction, the positions of the peaks P1 and P2 will be closer to the side surfaces S1 and S2.

[0085] Furthermore, the separation distance Wp between the apexes P1 and P2 and the first and second peak dimensions D1 and D2 can be adjusted by adjusting the dimension in the Y-axis direction of the water-repellent region Q. For example, the narrower the dimension in the Y-axis direction of the water-repellent region Q, the narrower the separation distance Wp and the larger the first and second peak dimensions D1 and D2.

[0086] Furthermore, to make the first peak dimension D1 larger than the second peak dimension D2, for example, the water-repellent region Q can be biased toward the first side surface S1 or the second side surface S2. The uncured resin paste Ps2 wets and rises more significantly along the side edge Qs of the water-repellent region Q, which is located closer to the center in the Y-axis direction. By positioning one side edge Qs of the water-repellent region Q closer to the center in the Y-axis direction than the other side edge Qs, the magnitudes of the first peak dimension D1 and the second peak dimension D2 can be changed. Furthermore, the magnitudes of the first peak dimension D1 and the second peak dimension D2 can be changed by biasing the coating amount of the water-repellent material formed in the water-repellent region Q. The peak dimension becomes smaller when the coating amount of the water-repellent material is increased. Furthermore, by increasing the coating amount of the water-repellent material formed over the entire water-repellent region Q, the depression between the first and second apexes P1 and P2 can be made larger, and by decreasing the coating amount, the depression can be made smaller.

[0087] The first and second peak dimensions D1, D2 can also be adjusted by the depth in the X-axis direction to which the uncured resin paste Ps2 is immersed. As an example, the depth to which the ceramic body 11 is immersed in the uncured resin paste Ps2 can be set to a depth equivalent to the dimension of the base layer 14 in the X-axis direction. This allows the minimum dimension D0 to be kept approximately the dimension of the base layer 14 in the X-axis direction. Note that, although the first and second peak dimensions D1, D2 increase as the depth to which the uncured resin paste Ps2 is immersed in the X-axis direction increases, this method also increases the minimum dimension D0.

[0088] The first and second peak dimensions D1, D2 and the ratios (D1 / D0, D2 / D0) of the first and second peak dimensions D1, D2 to the minimum dimension D0 can also be adjusted by the physical properties of the uncured resin paste Ps2. For example, using an uncured resin paste Ps2 that easily wets the ceramic body 11 can promote wetting of the uncured resin paste Ps2 after immersion, thereby increasing the first and second peak dimensions D1, D2 and the ratios (D1 / D0, D2 / D0). Furthermore, reducing the viscosity of the uncured resin paste Ps2 can also promote wetting, thereby increasing the first and second peak dimensions D1, D2 and the ratios (D1 / D0, D2 / D0). The viscosity of the uncured resin paste Ps2 can be, for example, 1.0 Pa·s or more and 50 Pa·s or less.

[0089] Other conditions for step S33 can also be determined as appropriate. In addition to the above conditions, for example, the immersion time in the uncured resin paste Ps2 and the temperature of the uncured resin paste Ps2 may be changed while observing the shape of the uncured resin to be formed. Furthermore, the uncured resin layer 15u after immersion can be dried under predetermined conditions.

[0090] (Step S34: Heat curing treatment) In step S34, the formed uncured resin layer 15u 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 15u is thermally cured, and the conductive resin layer 15 is formed.

[0091] (Step S35: Plating layer formation) In step S35, a plated layer 16 is formed by wet plating on the base layer 14 and the conductive resin layer 15 formed on the ceramic body 11. For example, the plated layer 16 may be formed by forming Ni plating on the conductive resin layer 15 and then forming Sn plating on top of that. This completes the external electrodes 13a, 13b. Because the plated layer 16 is formed by wet plating to follow the contours of the base layer 14 and the conductive resin layer 15, first convex portions 131 and second convex portions 132 resulting from the shape of the conductive resin layer 15 are formed on the external electrodes 13a, 13b.

[0092] (Variation) The above-described manufacturing method can be modified in various ways as long as the configuration of the multilayer ceramic capacitor 10 of this embodiment can be obtained. For example, the method for forming the external electrodes 13a, 13b is not limited to the above-described method as long as it is possible to form the base layer 14 and the conductive resin layer 15. For example, the method for forming the uncured resin layer 15u is not limited to the method for forming the water-repellent region Q, and it is also possible to form a mask on the ceramic body 11 that exposes the region where the conductive resin layer 15 is to be formed, and then apply a conductive resin paste to the portion exposed by the mask.

[0093] <Other embodiments> Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments and that various modifications can be made.

[0094] The conductive resin layer 15 only needs to be located on the principal surface covering portion 13m on at least one of the principal surfaces (first principal surface M1), and does not need to be located on the end surface covering portion 13e and the side surface covering portion 13s. Furthermore, the principal surface covering portion 13m including the first convex portion 131 and the second convex portion 132 only needs to be located on at least one of the principal surfaces (first principal surface M1).

[0095] The external electrodes 13a and 13b do not necessarily have to have the side surface covering portions 13s.

[0096] The shapes of the first and second convex portions 131, 132 are not limited to the above example, and for example, the first peak dimension D1 and the second peak dimension D2 may be the same.

[0097] For example, the underlayer 14 may have a plurality of layers. For example, the underlayer 14 may include a sintered film and a plated film. Alternatively, the underlayer 14 may include a sputtered film and a sintered film.

[0098] The internal electrodes 12a, 12b are not limited to being arranged alternately along the Z-axis direction, but may be arranged alternately along the Y-axis direction, for example.

[0099] The multilayer ceramic capacitor according to this embodiment is not limited to a two-terminal type, but can also be configured as a three-terminal type.

[0100] Furthermore, the present invention is applicable not only to multilayer ceramic capacitors but also to all multilayer ceramic electronic components having external electrodes, such as chip varistors, chip thermistors, and multilayer inductors, in addition to multilayer ceramic capacitors. [Explanation of symbols]

[0101] 10...Multilayer ceramic capacitors (multilayer ceramic electronic components) 11...Ceramic body 12a, 12b…Internal electrode 13a,13b...External electrode 13e...End face covering part 13m…Main surface covering part 14…base layer 15...Conductive resin layer 16...Plating layer 131...First convex part 132...Second convex part P1...first top P2…Second top

Claims

1. a substantially rectangular parallelepiped ceramic body having a pair of main surfaces perpendicular to a first axis, a pair of end faces perpendicular to a second axis orthogonal to the first axis, a pair of side surfaces perpendicular to a third axis orthogonal to the first axis and the second axis, and a plurality of internal electrodes extended to the pair of end faces; a pair of external electrodes facing each other in the second axial direction, each external electrode having an end surface covering portion covering the end surface, a main surface covering portion formed continuously from the end surface covering portion and covering a portion of the main surface, and a base layer extending from the end surface covering portion to the portion of the main surface covering portion; Equipped with The main surface covering portion is a conductive resin layer covering the underlayer and extending further toward the center in the second axis direction than the underlayer; a first convex portion and a second convex portion that are formed based on the shape of the conductive resin layer, each of which bulges toward a center in the second axis direction and is arranged to be spaced apart in the third axis direction, Furthermore, the first protrusion and the second protrusion have a minimum dimension in the second axis direction on the outer sides in the third axis direction, the minimum dimension is substantially equal to the dimension of the underlayer in the second axis direction; Multilayer ceramic electronic components.

2. 2. The multilayer ceramic electronic component according to claim 1, A first peak dimension in the second axis direction from an outer edge portion on the outside of the second axis direction of the principal surface covering portion to a first apex located at the center side in the second axis direction of the first convex portion, and a second peak dimension in the second axis direction from the outer edge portion to a second apex located at the center side in the second axis direction of the second convex portion, are each 1.5 times or more the minimum dimension in the second axis direction of the principal surface covering portion. Multilayer ceramic electronic components.

3. 3. The multilayer ceramic electronic component according to claim 1, a first peak dimension in the second axis direction from an outer edge portion on an outer side in the second axial direction of the main surface covering portion to a first apex located at the center most side in the second axial direction of the first convex portion, and a second peak dimension in the second axis direction from the outer edge portion to a second apex located at the center most side in the second axial direction of the second convex portion, each being 1 / 10 or more and 2 / 5 or less of the dimension of the monolithic ceramic electronic component in the second axis direction. Multilayer ceramic electronic components.

4. 4. The multilayer ceramic electronic component according to claim 1, A first peak dimension in the second axis direction from an outer edge portion on the outside of the main surface covering portion in the second axis direction to a first apex located at the center side in the second axis direction in the first convex portion is larger than a second peak dimension in the second axis direction from the outer edge portion to a second apex located at the center side in the second axis direction in the second convex portion. Multilayer ceramic electronic components.

5. 5. The multilayer ceramic electronic component according to claim 4, The first peak dimension is 1.1 times or more and 1.5 times or less than the second peak dimension. Multilayer ceramic electronic components.

6. 6. The multilayer ceramic electronic component according to claim 1, a distance in the third axis direction between a first apex located at the most central side in the second axis direction of the first protrusion and a second apex located at the most central side in the second axis direction of the second protrusion is equal to or greater than 1 / 5 and equal to or less than 1 / 2 of a dimension of the multilayer ceramic electronic component in the third axis direction; Multilayer ceramic electronic components.

7. 7. The multilayer ceramic electronic component according to claim 1, a plating layer that forms a surface layer of the end surface covering portion and the main surface covering portion, The first convex portion and the second convex portion have a laminated structure of the conductive resin layer and the plating layer. Multilayer ceramic electronic components.

8. The multilayer ceramic electronic component includes a mounting substrate having connection electrodes, The multilayer ceramic electronic component comprises: a substantially rectangular parallelepiped ceramic body having a pair of main surfaces perpendicular to a first axis, a pair of end faces perpendicular to a second axis orthogonal to the first axis, a pair of side surfaces perpendicular to a third axis orthogonal to the first axis and the second axis, and a plurality of internal electrodes extended to the pair of end faces; a pair of external electrodes facing each other in the second axial direction, each external electrode having an end surface covering portion covering the end surface, a main surface covering portion formed continuously from the end surface covering portion and covering a portion of the main surface, and a base layer extending from the end surface covering portion to the portion of the main surface covering portion; Equipped with The main surface covering portion is a conductive resin layer covering the underlayer and extending further toward the center in the second axis direction than the underlayer; a first convex portion and a second convex portion that are formed based on the shape of the conductive resin layer, each of which bulges toward a center in the second axial direction and is arranged to be spaced apart in the third axial direction, Furthermore, the first protrusion and the second protrusion have a minimum dimension in the second axis direction on the outer side in the third axis direction, and is disposed opposite the connection electrode, the minimum dimension is substantially equal to the dimension of the underlayer in the second axis direction; Circuit board.

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