Multilayer ceramic electronic component

Abstract

To provide a multilayer ceramic electronic component that can suppress an electrostriction crack and a thermal crack.SOLUTION: A multilayer ceramic electronic component has: a laminate having an internal electrode group made up of a plurality of internal electrodes laminated along a first shaft and a plurality of ceramic layers positioned between adjacent internal electrodes; and a pair of external electrodes connected to the plurality of internal electrodes, where the internal electrode group includes: a first internal electrode group of the plurality of internal electrodes which are made up of one or more first internal electrodes positioned at an end part in a first direction of the first shaft; a second internal electrode group of the plurality of internal electrodes which are made up of one or more second internal electrodes positioned at an end part in a second direction on the opposite side of the first direction of the first shaft; and a third internal electrode group of the plurality of internal electrodes which are made up of one or more third internal electrodes positioned between the first internal electrode group and the second internal electrode group, and a first coefficient of thermal expansion of the first internal electrodes and a second coefficient of thermal expansion of the second internal electrodes are lower than a third coefficient of thermal expansion of the third internal electrodes.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a multilayer ceramic electronic component.

Background Art

[0002] Multilayer ceramic capacitors are used for noise bypass, voltage stabilization, etc. in high-frequency circuits and power circuits. A multilayer ceramic capacitor mainly includes a capacitance forming portion in which a plurality of internal electrodes and dielectric layers are alternately laminated, a pair of external electrodes covering a pair of end faces of the capacitance forming portion, a margin portion covering a pair of side faces of the capacitance forming portion, and a cover portion covering a pair of main faces of the capacitance forming portion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a voltage is applied to the internal electrode of a multilayer ceramic capacitor, due to the piezoelectric effect of the dielectric layer, the capacitance forming portion tends to expand in the lamination direction of the internal electrode and the dielectric layer. On the other hand, since the piezoelectric effect does not act on the margin portion, the margin portion does not tend to deform. For this reason, tensile stress acts on the margin portion, and cracks may occur starting from the boundary between the capacitance forming portion and the margin portion. In the present disclosure, such cracks may be referred to as electrostrictive cracks.

[0005] In addition, multilayer ceramic capacitors may be mounted on a substrate using solder and used. In this case, during soldering for mounting, the multilayer ceramic capacitor is exposed to a temperature equal to or higher than the melting point of the solder, for example, a temperature of about 300°C to 400°C. When the multilayer ceramic capacitor is exposed to a temperature equal to or higher than the melting point of the solder, the internal electrodes and the external electrodes greatly thermally expand, while the thermal expansion of the margin portion and the cover portion is small. For this reason, cracks may occur starting from the portion where the edge of the external electrode of the cover portion contacts. In the present disclosure, such cracks may be referred to as thermal cracks.

[0006] In conventional multilayer ceramic capacitors, it is difficult to suppress both piezoelectric cracks and thermal cracks.

[0007] An object of the present disclosure is to provide a multilayer ceramic electronic component capable of suppressing piezoelectric cracks and thermal cracks.

Means for Solving the Problems

[0008] According to one aspect of the present disclosure, a multilayer ceramic electronic component includes a laminate having an internal electrode group composed of a plurality of internal electrodes laminated along a first axis, and a plurality of ceramic layers positioned between adjacent internal electrodes, and a pair of external electrodes connected to the plurality of internal electrodes. The internal electrode group includes a first internal electrode group composed of one or more first internal electrodes positioned at an end in a first direction of the first axis among the plurality of internal electrodes, a second internal electrode group composed of one or more second internal electrodes positioned at an end in a second direction opposite to the first direction of the first axis among the plurality of internal electrodes, and a third internal electrode group composed of one or more third internal electrodes positioned between the first internal electrode group and the second internal electrode group among the plurality of internal electrodes. The first coefficient of thermal expansion of the first internal electrode and the second coefficient of thermal expansion of the second internal electrode are lower than the third coefficient of thermal expansion of the third internal electrode.

Advantages of the Invention

[0009] According to the present disclosure, electrostrictive cracks and thermal cracks can be suppressed.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described in detail, but the present disclosure is not limited thereto. In this specification and the drawings, components having substantially the same functional configuration may be denoted by the same reference numerals, and redundant descriptions may be omitted. In the drawings, an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other are shown as appropriate. The X-axis, the Y-axis, and the Z-axis define a fixed coordinate system fixed to the multilayer ceramic capacitor.

[0012] (First Embodiment) First, the first embodiment will be described. The first embodiment relates to a multilayer ceramic capacitor.

[0013] [Structure of Multilayer Ceramic Capacitor] FIG. 1 is a perspective view showing a multilayer ceramic capacitor according to the first embodiment. FIGS. 2 and 3 are cross-sectional views showing the multilayer ceramic capacitor according to the first embodiment. FIG. 2 is a cross-sectional view taken along line A-A' in FIG. 1. FIG. 3 is a cross-sectional view taken along line B-B' in FIG. 1.

[0014] The multilayer ceramic capacitor 10 according to the first embodiment includes a ceramic body 11, an external electrode 14 of a first polarity, and an external electrode 15 of a second polarity. The ceramic body 11 is configured as a hexahedron having a pair of end faces orthogonal to the X axis, a pair of side faces orthogonal to the Y axis, and a pair of main faces orthogonal to the Z axis. In the examples of FIGS. 1 to 3, the external electrodes 14 and 15 cover a pair of end faces of the ceramic body 11. The external electrodes may be provided not only on the end faces but also on the surface of the ceramic body 11.

[0015] All of the pair of end faces, the pair of side faces, and the pair of main faces of the ceramic body 11 are configured as flat surfaces. The flat surface in the present embodiment does not have to be a strictly flat plane as long as it is recognized as flat when viewed as a whole, and includes, for example, a surface having a minute uneven shape on the surface or a gentle curved shape existing in a predetermined range.

[0016] In the examples of FIGS. 1 to 3, the external electrodes 14 and 15 face each other along the X axis with the ceramic body 11 interposed therebetween. The external electrodes 14 and 15 extend from the respective end faces of the ceramic body 11 to the main faces and the side faces. As a result, in the external electrodes 14 and 15, both a cross section parallel to the X-Z plane and a cross section parallel to the X-Y plane are U-shaped.

[0017] Note that the shapes of the external electrodes 14 and 15 are not limited to those shown in FIG. 1. For example, the external electrodes 14 and 15 may extend from both end faces of the ceramic element body 11 only to one main surface, and the cross section parallel to the X-Z plane may be L-shaped. Also, the external electrodes 14 and 15 may not extend to any main surface or side surface. For example, both of the two external electrodes may be provided on one main surface with a space therebetween. The external electrodes are not limited to the form of FIG. 1 as long as they are provided separately from each other on an arbitrary surface of the ceramic element body 11.

[0018] The external electrodes 14 and 15 are formed of a good electrical conductor. Examples of the good electrical conductor forming the external electrodes 14 and 15 include metals or alloys mainly composed of copper (Cu), nickel (Ni), tin (Sn), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), etc. In this embodiment, the main component refers to the component with the highest content ratio.

[0019] The ceramic element body 11 has a laminate 16 and a pair of side margin portions 17. The laminate 16 has a pair of side surfaces F that are parallel to the first axis, which is the lamination direction, and are in contact with the pair of side margin portions 17. In the examples of FIGS. 1 to 3, the laminate 16 constitutes a pair of main surfaces and a pair of end faces of the ceramic element body 11, and has side surfaces F that are a pair of surfaces in contact with the pair of side margin portions 17 perpendicular to the Y axis. Each of the pair of side margin portions 17 covers the pair of side surfaces F of the laminate 16, and the pair of surfaces facing the covering surfaces of the side margin portions 17 constitute a pair of surfaces of the ceramic element body 11.

[0020] The laminate 16 has a configuration in which a plurality of flat ceramic layers extending along a plane perpendicular to the first axis, which is the stacking direction, are stacked along the first axis. The laminate 16 has a capacitance forming portion 18 and a pair of cover portions 19. The pair of cover portions 19 cover the capacitance forming portion 18 from above and below along the first axis and constitute a pair of surfaces of the ceramic element 11. The plurality of ceramic layers include a plurality of inter-electrode ceramic layers 21 included in the capacitance forming portion 18 and a pair of outermost ceramic layers 22 included in the pair of cover portions 19. The pair of outermost ceramic layers sandwich the capacitance forming portion 18 along the first axis. That is, in the example of FIG. 1, the laminate 16 has a configuration in which a plurality of flat ceramic layers extending along the X-Y plane perpendicular to the Z axis, which is the stacking direction, are stacked along the Z axis. The laminate 16 has a capacitance forming portion 18 and a pair of cover portions 19. The pair of cover portions 19 cover the capacitance forming portion 18 from above and below along the Z axis and constitute a pair of main surfaces of the ceramic element 11. The plurality of ceramic layers include a plurality of inter-electrode ceramic layers 21 included in the capacitance forming portion 18 and a pair of outermost ceramic layers 22 included in the pair of cover portions 19. The pair of outermost ceramic layers sandwich the capacitance forming portion 18 along the Z axis.

[0021] The capacitance forming portion 18 has a plurality of first-polarity internal electrodes 12 and second-polarity internal electrodes 13 in a sheet shape extending along a plane perpendicular to the first axis, which is the stacking direction, in the example of FIG. 1, the X-Y plane. The internal electrodes 12 and the internal electrodes 13 are arranged between the plurality of ceramic layers. The internal electrodes 12 and the internal electrodes 13 are alternately arranged along the first axis, which is the stacking direction, in the example of FIG. 1, the Z axis. That is, in the capacitance forming portion 18, the internal electrodes 12 and the internal electrodes 13 face each other along the first axis, which is the stacking direction, in the example of FIG. 1, the Z axis, with the ceramic layers interposed therebetween.

[0022] The internal electrode 12 is drawn out to the surface of the ceramic element 11 covered by the external electrode 14, which is the end face in the example of FIG. 1. On the other hand, the internal electrode 13 is drawn out to the surface of the ceramic element 11 covered by the external electrode 15, which is the end face in the example of FIG. 1. As a result, the internal electrode 12 is connected only to the external electrode 14, and the internal electrode 13 is connected only to the external electrode 15.

[0023] The capacitance forming portion 18 has a pair of side margin portions in a direction perpendicular to the first axis which is the stacking direction, and is adjacent to both side surfaces F of the capacitance forming portion 18. The internal electrode 12 and the internal electrode 13 may be formed so as to be in contact with the side margin portions in a direction perpendicular to the first axis which is the stacking direction of the capacitance forming portion 18, and both ends may be located on both side surfaces F of the laminate 16.

[0024] The internal electrode 12 and the internal electrode 13 are formed of a good electrical conductor. Typical examples of the good electrical conductor forming the internal electrode 12 and the internal electrode 13 include nickel (Ni) or an alloy mainly composed of nickel.

[0025] With such a configuration, in the multilayer ceramic capacitor 10, when a voltage is applied between the external electrode 14 and the external electrode 15, a voltage is applied to the plurality of inter-electrode ceramic layers 21 between the internal electrode 12 and the internal electrode 13. As a result, in the multilayer ceramic capacitor 10, charges corresponding to the voltage between the external electrode 14 and the external electrode 15 are stored.

[0026] In the ceramic element 11 of the multilayer ceramic capacitor 10, the plurality of ceramic layers constituting the capacitance forming portion 18, the pair of cover portions 19, and the pair of side margin portions 17 are all mainly composed of polycrystals of dielectric ceramic. In the ceramic element 11, it is preferable that the ceramics constituting any of the above portions have the same composition system.

[0027] In the ceramic element 11, in order to increase the capacitance of each ceramic layer of the capacitance forming portion 18, a dielectric ceramic having a high dielectric constant is used. Examples of the dielectric ceramic having a high dielectric constant include barium titanate (BaTiO3 ) include materials with a perovskite structure containing barium (Ba) and titanium (Ti), represented by

[0028] Note that the ceramic layer is strontium titanate (SrTiO 3 ), calcium titanate (CaTiO 3 ), magnesium titanate (MgTiO 3 ), calcium zirconate (CaZrO 3 ), calcium zirconate titanate (Ca(Zr,Ti)O 3 ), barium zirconate (BaZrO 3 ), titanium oxide (TiO 2 ), etc.

[0029] Here, the thermal expansion coefficients of the internal electrodes 12 and 13 will be described. FIG. 4 is a diagram showing an internal electrode group in which the internal electrodes 12 and 13 are classified from the viewpoint of the thermal expansion coefficient in the first embodiment.

[0030] The plurality of internal electrodes 12 and 13 included in the laminate 16 constitute an internal electrode group 40. The internal electrode group 40 includes a first internal electrode group 41, a second internal electrode group 42, and a third internal electrode group 43. The first internal electrode group 41 is composed of one or more first internal electrodes 31 located at the end in the first direction (positive side) of the first axis, which is the stacking direction, the Z axis in the example of FIG. 4. The second internal electrode group 42 is composed of one or more second internal electrodes 32 located at the end in the second direction (negative side) opposite to the first direction of the first axis, which is the stacking direction, the Z axis in the example of FIG. 4. The third internal electrode group 43 is composed of one or more third internal electrodes 33 located between the first internal electrode group 41 and the second internal electrode group 42. Each of the first internal electrode 31, the second internal electrode 32, and the third internal electrode 33 is either the internal electrode 12 or the internal electrode 13.

[0031] In the first embodiment, the third coefficient of thermal expansion of the third internal electrode 33 is higher than the first coefficient of thermal expansion of the first internal electrode 31 and the second coefficient of thermal expansion of the second internal electrode 32. For example, the first internal electrode 31 and the second internal electrode 32 are made of nickel, and the third internal electrode 33 is made of an alloy mainly composed of nickel. Specifically, the third internal electrode 33 contains, for example, at least one additive element selected from the group consisting of indium, zinc, aluminum, tin, manganese, silver, copper, and gold, with nickel as the main component. The proportion of the additive element in the third internal electrode 33 is, for example, 0.2 at% or more and 3.0 at% or less. For example, the third coefficient of thermal expansion is higher than the coefficient of thermal expansion of nickel.

[0032] [Method for manufacturing a multilayer ceramic capacitor] Next, a method for manufacturing the multilayer ceramic capacitor 10 will be described. FIG. 5 is a flowchart showing the method for manufacturing the multilayer ceramic capacitor 10 according to the first embodiment.

[0033] (Step S01: Creation of an unfired internal electrode) Prepare an unfired ceramic sheet. A ceramic material is mixed with a binder, a solvent, etc., and coated on a film such as polyethylene terephthalate (PET) using an appropriate coating machine such as the doctor blade method and dried to obtain an unfired ceramic sheet. An unfired internal electrode 12 or an unfired internal electrode 13 is formed on the unfired ceramic sheet in an appropriate pattern by an appropriate method such as the screen printing method or the sputtering method. The unformed portion of the pattern around the appropriate pattern of the unfired internal electrode 12 or the unfired internal electrode 13 of the ceramic sheet becomes the side margin portion 17 and the end margin portion 20 after firing. A step compensation pattern made of a ceramic material can be provided or not provided at the periphery of the appropriate pattern to absorb the difference in thickness from the unfired internal electrodes 12 and 13. For the formation of the step compensation pattern, the screen printing method, the sputtering method, etc. can be appropriately used.

[0034] For example, the portions that will become the first internal electrode 31 and the second internal electrode 32 after firing are mainly composed of Ni, and the portion that will become the third internal electrode 33 after firing is composed of an alloy mainly composed of Ni having a larger coefficient of thermal expansion than the portions that will become the first internal electrode 31 and the second internal electrode 32.

[0035] (Step S02: Preparation of the green body) In step S02, a green body which is an unfired ceramic body 11 is prepared. The green body has an unfired laminate 16 and an unfired side margin portion 17. The unfired laminate 16 and the unfired side margin portion 17 can be produced using a laminated sheet in which a plurality of large-sized ceramic sheets are laminated along a first axis which is the lamination direction, in this example, the Z axis. Using the ceramic sheet on which the unfired internal electrode 12 formed in step S01 is formed and the ceramic sheet on which the unfired internal electrode 13 is formed, they are alternately laminated, and the portions that will become the first internal electrode 31, the portion that will become the second internal electrode 32, and the portion that will become the third internal electrode 33 are laminated in this order. Further, using a ceramic sheet on which no unfired internal electrode is formed above and below the first axis which is the lamination direction, in this example, the Z axis, the portion that will become the unfired cover portion 19 is laminated, and the unfired green body is obtained by thermocompression bonding. The portions that will become the first internal electrode 31, the second internal electrode 32, the third internal electrode 33, and the cover portion 19 after firing may be continuously laminated without individually laminating them. The green body includes a portion corresponding to the laminate 16 in which internal electrodes corresponding to the capacitance forming portion 18 after firing are alternately laminated, and a portion corresponding to the ceramic sheets laminated, corresponding to the pair of cover portions 19 after firing, and has portions corresponding to the side margin portions 17 after firing on both side surfaces thereof.

[0036] The side margin portion 17 can also be created independently of the laminate 16. In this case, a pattern-unformed portion is not formed at the peripheral portion of the pattern of the unfired internal electrode, and the internal electrode is exposed on the side surface of the molded body. By attaching a paste or sheet made of a ceramic material here, a molded body can be obtained. Existing manufacturing methods can be appropriately used except for creating the portions that will become the first internal electrode 31, the second internal electrode 32, and the third internal electrode 33.

[0037] (Step S03: Firing) In step S03, the ceramic green body 11 obtained in step S02 is fired to produce the ceramic green body 11 of the multilayer ceramic capacitor 10 shown in FIGS. 1 to 3.

[0038] (Step S04: Formation of External Electrodes) In step S04, the multilayer ceramic capacitor 10 shown in FIGS. 1 to 3 is produced by forming the external electrodes 14 and 15 at both ends in the two directions along the X-axis of the ceramic green body 11 fired in step S03. The method for forming the external electrodes 14 and 15 in step S04 can be arbitrarily selected from known methods. The external electrodes 14 and 15 may be formed on the surface of the molded body before firing and formed by co-firing with the molded body.

[0039] Thus, the multilayer ceramic capacitor 10 shown in FIGS. 1 to 3 is completed.

[0040] In the multilayer ceramic capacitor 10 according to the first embodiment, when the firing in step S03 is cooled, the first internal electrode 31, the second internal electrode 32, and the third internal electrode 33 thermally contract more than the dielectric ceramic, so that an internal stress in the compression direction acts on the capacitance forming portion 18. Further, since the third coefficient of thermal expansion of the third internal electrode 33 is higher than the first coefficient of thermal expansion of the first internal electrode 31 and the second coefficient of thermal expansion of the second internal electrode 32, a strong internal stress acts particularly around the third internal electrode group 43. Therefore, even when a voltage is applied between the internal electrode 12 and the internal electrode 13 and the inter-electrode ceramic layer 21 tries to expand along the Z axis due to the piezoelectric effect, the deformation of the inter-electrode ceramic layer 21 is suppressed by the internal stress in the compression direction along the Z axis. As a result, the deformation of the capacitance forming portion 18 along the Z axis is suppressed, and the electrostriction crack caused by the thermal expansion of the capacitance forming portion 18 can be suppressed. For example, the electrostriction crack can be reduced as compared with the case where all of the first internal electrode, the second internal electrode, and the third internal electrode are made of nickel.

[0041] The internal electrode 12 and the internal electrode 13 can be formed using a conductive paste, but are preferably formed by a sputtering method. This is because according to the sputtering method, the internal electrodes 12 and 13 can be formed with better uniformity, the uniformity of the internal stress generated in the capacitance forming portion 18 is increased, and it becomes easier to suppress electrostriction cracks.

[0042] If only the suppression of electrostriction cracks is aimed at, the first internal electrode 31 and the second internal electrode 32 can be made of a material containing nickel as a main component and at least one additive element selected from the group consisting of indium, zinc, aluminum, tin, manganese, silver, copper, and gold, like the third internal electrode 33. However, in this case, although electrostriction cracks can be suppressed, the first internal electrode 31 and the second internal electrode 32 thermally expand greatly during mounting on the substrate, and thermal cracks are likely to occur.

[0043] In contrast, according to the first embodiment, when the multilayer ceramic capacitor 10 is mounted on the substrate, since the thermal expansion of the first internal electrode 31 and the second internal electrode 32 located in the vicinity of the cover portion 19 does not increase, thermal cracks can be suppressed.

[0044] (Second Embodiment) Next, the second embodiment will be described. The second embodiment is mainly different from the first embodiment in terms of the material of the internal electrode group. FIG. 6 is a diagram showing an internal electrode group in which the internal electrodes 12 and 13 are classified from the viewpoint of the coefficient of thermal expansion in the second embodiment.

[0045] In the second embodiment, a plurality of internal electrodes 12 and 13 included in the laminate 16 constitute an internal electrode group 240. The internal electrode group 240 includes a first internal electrode group 241 instead of the first internal electrode group 41, includes a second internal electrode group 242 instead of the second internal electrode group 42, and includes a third internal electrode group 243 instead of the third internal electrode group 43. The first internal electrode group 241 is composed of one or more first internal electrodes 231 located at the end portion in the first direction (positive side) of the first axis which is the stacking direction, the Z axis in the example of FIG. 6. The second internal electrode group 242 is composed of one or more second internal electrodes 232 located at the end portion in the second direction (negative side) opposite to the first direction of the first axis which is the stacking direction, the Z axis in the example of FIG. 6. The third internal electrode group 243 is composed of one or more third internal electrodes 233 located between the first internal electrode group 241 and the second internal electrode group 242. Each of the first internal electrode 231, the second internal electrode 232, and the third internal electrode 233 is either the internal electrode 12 or the internal electrode 13.

[0046] In the second embodiment, the first coefficient of thermal expansion of the first internal electrode 231 and the second coefficient of thermal expansion of the second internal electrode 232 are lower than the third coefficient of thermal expansion of the third internal electrode 233. However, the materials are different from those in the first embodiment. For example, the first internal electrode 231 and the second internal electrode 232 are made of an alloy mainly composed of nickel, and the third internal electrode 233 is made of nickel. Specifically, the first internal electrode 231 and the second internal electrode 232 mainly contain nickel and at least one additive element selected from the group consisting of palladium, yttrium, platinum, titanium, vanadium, niobium, tantalum, germanium, hafnium, zirconium, silicon, and gallium. The proportion of the additive element in the first internal electrode 231 and the second internal electrode 232 is, for example, 0.2 at% or more and 3.0 at% or less. For example, the first coefficient of thermal expansion and the second coefficient of thermal expansion are lower than the coefficient of thermal expansion of nickel.

[0047] Other configurations of the second embodiment are the same as those of the first embodiment.

[0048] In manufacturing the multilayer ceramic capacitor according to the second embodiment, the materials of the portions that will become the unfired first internal electrode 231, second internal electrode 232, and third internal electrode 233 may be changed from the materials of the portions that will become the first internal electrode 31, second internal electrode 32, and third internal electrode 33 in the first embodiment. For example, the portion that will become the third internal electrode 233 after firing is mainly composed of Ni, and the portions that will become the first internal electrode 231 and the second internal electrode 232 after firing are made of an alloy mainly composed of Ni with a lower coefficient of thermal expansion than the portion that will become the third internal electrode 233.

[0049] In the multilayer ceramic capacitor according to the second embodiment, since the first coefficient of thermal expansion of the first internal electrode 231 and the second coefficient of thermal expansion of the second internal electrode 232 are lower than the third coefficient of thermal expansion of the third internal electrode 233, when the multilayer ceramic capacitor is mounted on the substrate, the thermal expansion of the first internal electrode 231 and the second internal electrode 232 located near the cover portion 19 becomes particularly small. As a result, thermal cracking can be suppressed.

[0050] If only the suppression of thermal cracks is aimed at, the third internal electrode 233 can be made of a material containing nickel as the main component and at least one additive element selected from the group consisting of palladium, yttrium, platinum, titanium, vanadium, niobium, tantalum, germanium, hafnium, zirconium, silicon, and gallium, similar to the first internal electrode 231 and the second internal electrode 232. However, in this case, although thermal cracks can be suppressed, the internal stress in the compression direction of the capacitance forming portion 18 becomes small, and electrostrictive cracks are likely to occur.

[0051] On the other hand, according to the second embodiment, since sufficient internal stress in the compression direction acts on the capacitance forming portion 18, electrostrictive cracks can be suppressed.

[0052] Generally, the Young's modulus of an alloy containing nickel as the main component and having a lower coefficient of thermal expansion than nickel is lower than the Young's modulus of nickel. In the second embodiment, it is preferable that the Young's modulus of the first internal electrode 231 and the Young's modulus of the second internal electrode 232 are lower than the Young's modulus of nickel. The substrate on which the multilayer ceramic capacitor is mounted may be bent by an external stress or a thermal stress or the like. When the substrate is bent, stress acts on the multilayer ceramic capacitor through the solder, and if the internal electrode is greatly deformed, cracks may occur in the cover portion or the like, similar to thermal cracks. In the present disclosure, such cracks may be referred to as substrate bending cracks.

[0053] When the Young's modulus of the first internal electrode 231 and the Young's modulus of the second internal electrode 232 are lower than the Young's modulus of nickel, the first internal electrode 231 and the second internal electrode 232 are less likely to deform even if the substrate is bent. Therefore, when the Young's modulus of the first internal electrode 231 and the Young's modulus of the second internal electrode 232 are lower than the Young's modulus of nickel, substrate bending cracks are also likely to be suppressed.

[0054] (Third Embodiment) Next, the third embodiment will be described. The third embodiment mainly differs from the first embodiment in terms of the material of the internal electrode group. FIG. 7 is a diagram showing an internal electrode group obtained by classifying internal electrodes 12 and 13 from the viewpoint of the coefficient of thermal expansion in the third embodiment.

[0055] In the third embodiment, a plurality of internal electrodes 12 and 13 included in the laminate 16 constitute an internal electrode group 340. The internal electrode group 340 includes a first internal electrode group 341 instead of the first internal electrode group 41, includes a second internal electrode group 342 instead of the second internal electrode group 42, and includes a third internal electrode group 343 instead of the third internal electrode group 43. The first internal electrode group 341 is composed of one or more first internal electrodes 331 located at the end portion in the first direction (positive side) of the first axis which is the stacking direction, the Z axis in the example of FIG. 7. The second internal electrode group 342 is composed of one or more second internal electrodes 332 located at the end portion in the second direction (negative side) opposite to the first direction of the first axis which is the stacking direction, the Z axis in the example of FIG. 7. The third internal electrode group 343 is composed of one or more third internal electrodes 333 located between the first internal electrode group 341 and the second internal electrode group 342. Each of the first internal electrode 331, the second internal electrode 332, and the third internal electrode 333 is either the internal electrode 12 or the internal electrode 13.

[0056] In the third embodiment, the first coefficient of thermal expansion of the first internal electrode 331 and the second coefficient of thermal expansion of the second internal electrode 332 are lower than the third coefficient of thermal expansion of the third internal electrode 333. However, the material is different from that of the first embodiment. For example, the first internal electrode 331 and the second internal electrode 332 are made of an alloy mainly composed of the same nickel as the first internal electrode 231 and the second internal electrode 232 in the second embodiment. On the other hand, the third internal electrode 333 is made of an alloy mainly composed of the same nickel as the third internal electrode 33 in the first embodiment.

[0057] Other configurations of the third embodiment are the same as those of the first embodiment.

[0058] In manufacturing the multilayer ceramic capacitor according to the third embodiment, the material of the portions that will become the unfired first internal electrode 331 and second internal electrode 332 may be changed from the material of the portions that become the first internal electrode 31 and second internal electrode 32 in the first embodiment. For example, after firing, the portions that become the first internal electrode 331 and the second internal electrode 332 are made of an alloy mainly composed of the same Ni as the portions that become the first internal electrode 231 and the second internal electrode 232 after firing.

[0059] In the multilayer ceramic capacitor according to the third embodiment, similar to the first embodiment, particularly strong internal stress acts around the third internal electrode group 343, and it is possible to suppress the electrostriction cracks caused by the thermal expansion of the capacitance forming portion 18.

[0060] Also, similar to the second embodiment, when mounting the multilayer ceramic capacitor on the substrate, the thermal expansion of the first internal electrode 331 and the second internal electrode 332 located near the cover portion 19 becomes particularly small. As a result, thermal cracks can be suppressed. Further, when the Young's modulus of the first internal electrode 331 and the Young's modulus of the second internal electrode 332 are lower than the Young's modulus of nickel, substrate deflection cracks are also easily suppressed.

[0061] In each embodiment, the thicknesses of the first internal electrodes 31, 231, 331, the second internal electrodes 32, 232, 332, and the third internal electrodes 33, 233, 333 are substantially equal to each other, but they may be different. Also, the number of the first internal electrodes 31, 231, 331, the second internal electrodes 32, 232, 332, and the third internal electrodes 33, 233, 333 is not limited, and can be appropriately selected according to the thermal expansion coefficient of each of the first internal electrodes 31, 231, 331, the second internal electrodes 32, 232, 332, and the third internal electrodes 33, 233, 333, the soldering temperature, etc. For example, the ratio of the number of the first internal electrodes 31, 231, 331 to the total number of the first internal electrodes 31, 231, 331, the second internal electrodes 32, 232, 332, and the third internal electrodes 33, 233, 333 is 10% or more and 30% or less, the ratio of the number of the second internal electrodes 32, 232, 332 is 10% or more and 30% or less, and the ratio of the number of the third internal electrodes 33, 233, 333 is 40% or more and 80% or less.

[0062] Further, the main components of the internal electrodes 12 and 13 are not limited to nickel, and copper (Cu), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), etc. may be the main components of the internal electrodes 12 and 13.

[0063] [Other Embodiments] Although the embodiments have been described in detail above, the present disclosure is not limited to specific embodiments, and various modifications and changes are possible within the scope described in the claims.

[0064] For example, in the above embodiment, a multilayer ceramic capacitor has been described as an example of the multilayer ceramic electronic component, but the present disclosure is applicable to all multilayer ceramic electronic components. Examples of such multilayer ceramic electronic components include chip varistors, chip thermistors, multilayer inductors, and the like.

[0065] Aspects of the present disclosure are as follows, for example.

[0066] <1> A laminate having an internal electrode group composed of a plurality of internal electrodes laminated along a first axis, and a plurality of ceramic layers located between adjacent internal electrodes; A pair of external electrodes connected to the plurality of internal electrodes; And having The internal electrode group includes A first internal electrode group composed of one or more first internal electrodes located at an end of the plurality of internal electrodes in a first direction of the first axis; A second internal electrode group composed of one or more second internal electrodes located at an end of the plurality of internal electrodes in a second direction opposite to the first direction of the first axis; A third internal electrode group composed of one or more third internal electrodes located between the first internal electrode group and the second internal electrode group among the plurality of internal electrodes; And including A multilayer ceramic electronic component in which a first coefficient of thermal expansion of the first internal electrode and a second coefficient of thermal expansion of the second internal electrode are lower than a third coefficient of thermal expansion of the third internal electrode.

[0067] <2> The multilayer ceramic electronic component according to <1>, wherein the third coefficient of thermal expansion is 1.1 times or more and 1.5 times or less the first coefficient of thermal expansion and the second coefficient of thermal expansion.

[0068] <3> Elements of the main component of the first internal electrode, elements of the main component of the second internal electrode, and elements of the main component of the third internal electrode are common. The composition is different between the material of the first internal electrode and the material of the third internal electrode. The multilayer ceramic electronic component according to <1> or <2>, wherein the composition is different between the material of the second internal electrode and the material of the third internal electrode.

[0069] <4> The multilayer ceramic electronic component according to <3>, wherein the elements of the main component of the first internal electrode, the elements of the main component of the second internal electrode, and the elements of the main component of the third internal electrode are nickel.

[0070] <5> The multilayer ceramic electronic component according to <4>, wherein the third coefficient of thermal expansion is higher than the coefficient of thermal expansion of nickel.

[0071] <6> The multilayer ceramic electronic component according to <4> or <5>, wherein the third internal electrode contains at least one additive element selected from the group consisting of indium, zinc, aluminum, tin, manganese, silver, copper, and gold.

[0072] <7> The multilayer ceramic electronic component according to <4> or <5>, wherein the third internal electrode contains at least one additive element selected from the group consisting of zinc, aluminum, and manganese.

[0073] <8> The proportion of the additive element in the third internal electrode is 0.2 at% or more and 3.0 at% or less, and the multilayer ceramic electronic component according to <6> or <7>.

[0074] <9> The first thermal expansion coefficient and the second thermal expansion coefficient are lower than the thermal expansion coefficient of nickel, and the multilayer ceramic electronic component according to <4>.

[0075] <10> The first internal electrode and the second internal electrode contain at least one additive element selected from the group consisting of palladium, yttrium, platinum, titanium, vanadium, niobium, tantalum, germanium, hafnium, zirconium, silicon, and gallium, and the multilayer ceramic electronic component according to <9>.

[0076] <11> The first internal electrode and the second internal electrode contain at least one additive element selected from the group consisting of yttrium, platinum, niobium, tantalum, germanium, hafnium, zirconium, silicon, and gallium, and the multilayer ceramic electronic component according to <9>.

[0077] <12> The proportion of the additive element in each of the first internal electrode and the second internal electrode is 0.2 at% or more and 3.0 at% or less, and the multilayer ceramic electronic component according to <10> or <11>.

[0078] <13> The first thermal expansion coefficient and the second thermal expansion coefficient are lower than the thermal expansion coefficient of nickel, and the third thermal expansion coefficient is higher than the thermal expansion coefficient of nickel, and the multilayer ceramic electronic component according to <4>.

[0079] <14> The first internal electrode and the second internal electrode contain at least one additive element selected from the group consisting of palladium, yttrium, platinum, titanium, vanadium, niobium, tantalum, germanium, hafnium, zirconium, silicon, and gallium, and the third internal electrode contains at least one additive element selected from the group consisting of indium, zinc, aluminum, tin, manganese, silver, copper, and gold. The multilayer ceramic electronic component according to <13>.

[0080] <15> The first internal electrode and the second internal electrode contain at least one additive element selected from the group consisting of yttrium, platinum, niobium, tantalum, germanium, hafnium, zirconium, silicon, and gallium, and the third internal electrode contains at least one additive element selected from the group consisting of zinc, aluminum, and manganese. The multilayer ceramic electronic component according to <13>.

[0081] <16> The ratio of the additive element in the first internal electrode, the second internal electrode, and the third internal electrode is 0.2 at% or more and 3.0 at% or less. The multilayer ceramic electronic component according to <14> or <15>.

[0082] <17> The Young's modulus of the first internal electrode and the Young's modulus of the second internal electrode are lower than the Young's modulus of nickel. The multilayer ceramic electronic component according to any one of <9> to <12>.

[0083] <18> The Young's modulus of the first internal electrode and the Young's modulus of the second internal electrode are lower than the Young's modulus of nickel. The multilayer ceramic electronic component according to any one of <13> to <16>.

[0084] <19> With respect to the total number of the first internal electrode, the second internal electrode, and the third internal electrode, The ratio of the number of the first internal electrodes is 10% or more and 30% or less, The ratio of the number of the second internal electrodes is 10% or more and 30% or less, The ratio of the number of the third internal electrodes is 40% or more and 80% or less, the multilayer ceramic electronic component according to any one of <1> to <18>.

Explanation of symbols

[0085] 10 Multilayer ceramic capacitor 11 Ceramic body 12, 13 Internal electrodes 14, 15 External electrodes 16 Laminate 17 Side margin part 18 Capacitance forming part 19 Cover part 31 First internal electrode 32 Second internal electrode 33 Third internal electrode 40 Internal electrode group 41 First internal electrode group 42 Second internal electrode group 43 Third internal electrode group

Claims

1. A laminate including: an internal electrode group including a plurality of internal electrodes laminated along a first axis; and a plurality of ceramic layers positioned between adjacent ones of the internal electrodes; a pair of external electrodes connected to the plurality of internal electrodes; wherein the internal electrode group includes a first internal electrode group including one or more first internal electrodes positioned at an end of the plurality of internal electrodes in a first direction of the first axis; a second internal electrode group including one or more second internal electrodes positioned at an end of the plurality of internal electrodes in a second direction opposite to the first direction of the first axis; a third internal electrode group including one or more third internal electrodes positioned between the first internal electrode group and the second internal electrode group among the plurality of internal electrodes; and a first thermal expansion coefficient of the first internal electrode and a second thermal expansion coefficient of the second internal electrode are lower than a third thermal expansion coefficient of the third internal electrode, the multilayer ceramic electronic component.

2. The multilayer ceramic electronic component according to claim 1, wherein the third thermal expansion coefficient is 1.1 times or more and 1.5 times or less of the first thermal expansion coefficient and the second thermal expansion coefficient.

3. elements of a main component of the first internal electrode, elements of a main component of the second internal electrode, and elements of a main component of the third internal electrode are common; a composition is different between a material of the first internal electrode and a material of the third internal electrode; and a composition is different between a material of the second internal electrode and a material of the third internal electrode, the multilayer ceramic electronic component according to claim 1 or 2.

4. The multilayer ceramic electronic component according to claim 3, wherein the elements of the main component of the first internal electrode, the elements of the main component of the second internal electrode, and the elements of the main component of the third internal electrode are nickel.

5. The multilayer ceramic electronic component according to claim 4, wherein the third thermal expansion coefficient is higher than a thermal expansion coefficient of nickel.

6. The multilayer ceramic electronic component according to claim 5, wherein the third internal electrode includes at least one additive element selected from the group consisting of indium, zinc, aluminum, tin, manganese, silver, copper, and gold.

7. The multilayer ceramic electronic component according to claim 5, wherein the third internal electrode includes at least one additive element selected from the group consisting of zinc, aluminum, and manganese.

8. The multilayer ceramic electronic component according to claim 6, wherein a ratio of the additive element in the third internal electrode is 0.2 at% or more and 3.0 at% or less.

9. The laminated ceramic electronic component according to claim 4, wherein the first coefficient of thermal expansion and the second coefficient of thermal expansion are lower than the coefficient of thermal expansion of nickel.

10. The laminated ceramic electronic component according to claim 9, wherein the first internal electrode and the second internal electrode contain at least one additive element selected from the group consisting of palladium, yttrium, platinum, titanium, vanadium, niobium, tantalum, germanium, hafnium, zirconium, silicon, and gallium.

11. The laminated ceramic electronic component according to claim 9, wherein the first internal electrode and the second internal electrode contain at least one additive element selected from the group consisting of yttrium, platinum, niobium, tantalum, germanium, hafnium, zirconium, silicon, and gallium.

12. The laminated ceramic electronic component according to claim 10, wherein the ratio of the additive element in each of the first internal electrode and the second internal electrode is 0.2 at% or more and 3.0 at% or less.

13. The laminated ceramic electronic component according to claim 4, wherein the first coefficient of thermal expansion and the second coefficient of thermal expansion are lower than the coefficient of thermal expansion of nickel, and the third coefficient of thermal expansion is higher than the coefficient of thermal expansion of nickel.

14. The laminated ceramic electronic component according to claim 13, wherein the first internal electrode and the second internal electrode contain at least one additive element selected from the group consisting of palladium, yttrium, platinum, titanium, vanadium, niobium, tantalum, germanium, hafnium, zirconium, silicon, and gallium, and the third internal electrode contains at least one additive element selected from the group consisting of indium, zinc, aluminum, tin, manganese, silver, copper, and gold.

15. The laminated ceramic electronic component according to claim 13, wherein the first internal electrode and the second internal electrode contain at least one additive element selected from the group consisting of yttrium, platinum, niobium, tantalum, germanium, hafnium, zirconium, silicon, and gallium, and the third internal electrode contains at least one additive element selected from the group consisting of zinc, aluminum, and manganese.

16. The laminated ceramic electronic component according to claim 15, wherein the ratio of the additive element in the first internal electrode, the second internal electrode, and the third internal electrode is 0.2 at% or more and 3.0 at% or less.

17. The laminated ceramic electronic component according to claim 9, wherein the Young's modulus of the first internal electrode and the Young's modulus of the second internal electrode are lower than the Young's modulus of nickel.

18. The laminated ceramic electronic component according to claim 13, wherein the Young's modulus of the first internal electrode and the Young's modulus of the second internal electrode are lower than the Young's modulus of nickel.

19. With respect to the total number of the first internal electrode, the second internal electrode, and the third internal electrode, the ratio of the number of the first internal electrodes is 10% or more and 30% or less, the ratio of the number of the second internal electrodes is 10% or more and 30% or less, and the ratio of the number of the third internal electrodes is 40% or more and 80% or less, the laminated ceramic electronic component according to claim 1 or 2.

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