Electronic component and method for producing electronic component

Abstract

An electronic component (10) comprises an element body (20) and two external electrodes that cover an outer surface (21) of the element body (20). Each of the external electrodes has a base electrode. Each of the base electrodes includes a plurality of copper particles (CP) and a filler (64). Each of the base electrodes has a chain-shaped portion (63) in which the plurality of copper particles (CP) are linked to each other. When the base electrode is viewed in a cross section perpendicular to the outer surface (21) of the element body (20), the filler (64) fills a plurality of gaps (G) between different portions of the chain-shaped portion (63).

Description

Electronic component and method for manufacturing electronic component

[0001] The present disclosure relates to electronic components and methods for manufacturing electronic components.

[0002] The electronic component disclosed in Patent Document 1 has an element body, internal electrodes, and external electrodes. The internal electrodes are located inside the element body. The external electrodes have a base electrode and a metal layer. The base electrode covers a portion of the outer surface of the element body. The base electrode contains copper. The metal layer covers the outer surface of the base electrode.

[0003] Patent No. 5206440

[0004] In electronic components such as those disclosed in Patent Document 1, voids that are not filled with copper or resin may exist inside the base electrode. The more voids there are, the more easily liquid, such as a plating solution, that is used to form a metal layer can penetrate into the base electrode. If liquid penetrates into the base electrode, the base electrode may peel off from the element body or cracks may easily occur in the base electrode.

[0005] In order to solve the above problems, the present disclosure provides an electronic component comprising an element body and an external electrode covering an outer surface of the element body, the external electrode having a base electrode, the base electrode including a plurality of copper particles and a filler, the base electrode having a chain portion in which the plurality of copper particles are continuously connected from the outer surface of the element body to the outer surface of the base electrode opposite the element body, and in which the base electrode has a chain portion in which the plurality of copper particles are connected over a length of 100 nm or more in a direction along the outer surface of the element body, when viewed in cross section perpendicular to the outer surface of the element body, there are a plurality of gaps between different parts of the chain portion, and the filler is filled in the aforesaid gaps.

[0006] The present disclosure also provides a method for manufacturing an electronic component, including a laminate preparation step of preparing a base body, a conductor paste preparation step of preparing a conductor paste in which an amine and a carboxylic acid are added to a copper-containing solution, a conductor application step of applying the conductor paste to the outer surface of the base body, and a curing step of forming a base electrode on the outer surface of the base body by curing the conductor paste.

[0007] This can prevent liquid from penetrating into the base electrode.

[0008] Fig. 1 is a perspective view of an electronic component. Fig. 2 is a side view of the electronic component. Fig. 3 is a cross-sectional view of the electronic component. Fig. 4 is an enlarged cross-sectional view of an external electrode. Fig. 5 is an enlarged cross-sectional view of a base electrode. Fig. 6 is a flowchart of a method for manufacturing an electronic component.

[0009] <One embodiment of an electronic component and a method for manufacturing an electronic component> An embodiment of an electronic component and a method for manufacturing an electronic component will be described below. Note that the drawings are schematic diagrams for ease of understanding, and components may be enlarged or omitted. Therefore, the dimensional ratios of the components may differ from those of the actual components.

[0010] (Overall Configuration of the Electronic Component) As shown in FIG. 1 , the electronic component 10 is a multilayer ceramic capacitor. The electronic component 10 includes an element body 20. The element body 20 is generally rectangular prism-shaped and has a central axis CA. In the following description, an axis extending along the central axis CA is referred to as a first axis X. One of the axes perpendicular to the first axis X is referred to as a second axis Y. An axis perpendicular to the first axis X and the second axis Y is referred to as a third axis Z. One of the directions along the first axis X is referred to as a first positive direction X1, and the direction along the first axis X that is opposite to the first positive direction X1 is referred to as a first negative direction X2. One of the directions along the second axis Y is referred to as a second positive direction Y1, and the direction along the second axis Y that is opposite to the second positive direction Y1 is referred to as a second negative direction Y2. Furthermore, one of the directions along the third axis Z is defined as a third positive direction Z1, and the direction along the third axis Z opposite to the third positive direction Z1 is defined as a third negative direction Z2.

[0011] The outer surface 21 of the element body 20 has six flat surfaces 22. The term "surface" of the element body 20 as used herein refers to a surface that can be observed when the entire element body 20 is observed. In other words, even if there are minute irregularities or steps that are not visible unless a portion of the element body 20 is magnified and observed using a microscope or the like, the surface is still referred to as a flat or curved surface. The six flat surfaces 22 face in different directions. The six flat surfaces 22 are broadly divided into a first end surface 22A facing the first positive direction X1, a second end surface 22B facing the first negative direction X2, and four side surfaces 22C. The four side surfaces 22C are, respectively, a surface facing the third positive direction Z1, a surface facing the third negative direction Z2, a surface facing the second positive direction Y1, and a surface facing the second negative direction Y2.

[0012] In the outer surface 21 of the element body 20, the boundary portions between two adjacent flat surfaces 22 and the boundary portions between three adjacent flat surfaces 22 are curved. That is, the corners of the element body 20 are rounded and chamfered.

[0013] 1 and 2, the element body 20 has a dimension along the first axis X that is greater than the dimensions along the second axis Y and the dimensions along the third axis Z. The material of the element body 20 is a dielectric ceramic. Specifically, the material of the element body 20 is BaTiO ３ The main component of the element 20 is CaTiO ３ , SrTiO ３ , CaZrO ３ The material of the element body 20 may contain, as a secondary component, a Mn compound, a Co compound, a Si compound, or a compound containing a rare earth element.

[0014] 3 , the electronic component 10 includes four first internal electrodes 41 and four second internal electrodes 42. The first internal electrodes 41 and the second internal electrodes 42 are embedded inside the element body 20.

[0015] The first internal electrode 41 is made of a conductive material. Specifically, the first internal electrode 41 is made of Ni. The second internal electrode 42 is made of the same material as the first internal electrode 41.

[0016] The first internal electrode 41 has a rectangular plate shape. The main surface of the first internal electrode 41 is perpendicular to the second axis Y. The second internal electrode 42 has the same rectangular plate shape as the first internal electrode 41. The main surface of the second internal electrode 42 is perpendicular to the second axis Y, similar to the first internal electrode 41.

[0017] The dimension of the first internal electrode 41 in the direction along the first axis X is smaller than the dimension of the element body 20 in the direction along the first axis X. Also, as shown in Fig. 1 , the dimension of the first internal electrode 41 in the direction along the third axis Z is approximately two-thirds of the dimension of the element body 20 in the direction along the third axis Z. The dimensions of the second internal electrode 42 in each direction are approximately the same as those of the first internal electrode 41.

[0018] 3, the first internal electrodes 41 and the second internal electrodes 42 are positioned alternately in the direction along the second axis Y. That is, the first internal electrodes 41, the second internal electrodes 42, the first internal electrodes 41, and the second internal electrodes 42 are arranged in this order from the side surface 22C facing the second positive direction Y1 toward the second negative direction Y2. In this embodiment, the distances between the internal electrodes in the direction along the second axis Y are equal.

[0019] 1, the four first internal electrodes 41 and the four second internal electrodes 42 are all located at the center of the element body 20 in the direction along the third axis Z. On the other hand, as shown in Fig. 3, the first internal electrodes 41 are biased toward the first positive direction X1, and the second internal electrodes 42 are biased toward the first negative direction X2.

[0020] 3 , the end of the first internal electrode 41 on the first positive direction X1 side coincides with the end of the element body 20 on the first positive direction X1 side. Therefore, the end of the first internal electrode 41 on the first positive direction X1 side is exposed at the first end surface 22A. The end of the first internal electrode 41 on the first negative direction X2 side is located inside the element body 20 and does not reach the end of the element body 20 on the first negative direction X2 side. On the other hand, the end of the second internal electrode 42 on the first negative direction X2 side coincides with the end of the element body 20 on the first negative direction X2 side. Therefore, the end of the second internal electrode 42 on the first negative direction X2 side is exposed at the second end surface 22B. The end of the second internal electrode 42 on the first positive direction X1 side is located inside the element body 20 and does not reach the end of the element body 20 on the first positive direction X1 side.

[0021] 3, the electronic component 10 includes a first external electrode 61 and a second external electrode 62. In FIGS. 1 to 3, the first external electrode 61 and the second external electrode 62 are illustrated by two-dot chain lines.

[0022] The first external electrode 61 covers the first end face 22A and parts of the four side faces 22C of the element body 20 facing in the first positive direction X1. That is, the first external electrode 61 is a five-sided electrode. The first external electrode 61 includes a first base electrode 61A and a first metal layer 61B.

[0023] The first base electrode 61A is laminated on a portion of the outer surface 21 of the element body 20, including the first end face 22A. Specifically, the first base electrode 61A covers the first end face 22A and portions of the four side faces 22C of the element body 20 facing the first positive direction X1. In this embodiment, the first base electrode 61A is made of copper and a polymer compound containing carbon and nitrogen. The compound containing carbon and nitrogen is so-called inorganic carbon or organic carbon. The average dimension of the first base electrode 61A in a direction perpendicular to the outer surface 21 of the element body 20, i.e., the average thickness of the first base electrode 61A, is several μm. The arithmetic mean roughness of the outer surface 65 of the first base electrode 61A is 0.5 μm or more. Preferably, the arithmetic mean roughness of the outer surface 65 of the first base electrode 61A is 1 μm or more. More preferably, the arithmetic mean roughness of the outer surface 65 of the first base electrode 61A is 5 μm or more. In this embodiment, the arithmetic mean roughness of the outer surface 65 of the first base electrode 61A is 8 μm. The average thickness and arithmetic mean roughness are calculated, for example, by capturing a cross-sectional image of the first base electrode 61A using an electron microscope and processing the image. The detailed configuration of the first base electrode 61A will be described later.

[0024] The first metal layer 61B is laminated on the first base electrode 61A. That is, the first metal layer 61B externally covers the first base electrode 61A. The first metal layer 61B contains one or more metals selected from copper, nickel, silver, tin, palladium, and gold. In this embodiment, the first metal layer 61B has a Ni plating layer mainly composed of nickel and a Sn plating layer mainly composed of tin. Although not shown in the figure, the first metal layer 61B has a structure in which two layers, a Ni plating layer and a Sn plating layer, are laminated in this order from the first base electrode 61A side.

[0025] The second external electrode 62 covers the second end face 22B and parts of the four side faces 22C of the element body 20 facing in the second positive direction Y1. That is, the second external electrode 62 is a five-sided electrode. The second external electrode 62 includes a second base electrode 62A and a second metal layer 62B.

[0026] The second base electrode 62A is laminated on a portion of the outer surface 21 of the element body 20, including the second end face 22B. Specifically, the second base electrode 62A covers the second end face 22B of the element body 20 and portions of the four side faces 22C facing the first negative direction X2. In this embodiment, the material of the second base electrode 62A is the same as the material of the first external electrode 61. That is, the material of the second base electrode 62A is a compound containing copper and carbon as its main components. The average thickness of the second base electrode 62A and the arithmetic mean roughness of the outer surface of the second base electrode 62A are the same as those of the first base electrode 61A.

[0027] The second metal layer 62B is laminated on the second base electrode 62A. That is, the second metal layer 62B externally covers the second base electrode 62A. The material of the second metal layer 62B is the same as that of the first metal layer 61B. That is, the second metal layer 62B has a two-layer structure consisting of, in order from the second base electrode 62A side, a Ni-plated layer and a Sn-plated layer.

[0028] The second external electrode 62 does not reach the first external electrode 61 on the side surface 22C, and is spaced apart from the first external electrode 61 in the direction along the first axis X. Furthermore, the first external electrode 61 and the second external electrode 62 are not stacked in the central portion of the side surface 22C of the element body 20 in the direction along the first axis X.

[0029] (Base Electrode) A detailed description will be given below of the configuration of the first base electrode 61A in the first external electrode 61. Note that the configuration of the second base electrode 62A is similar to the configuration of the first base electrode 61A, and therefore description thereof will be omitted.

[0030] As shown in FIG. 4 , the first base electrode 61A contains a plurality of copper particles CP therein. The first base electrode 61A has a chain-like portion 63 in which the plurality of copper particles CP are connected. The chain-like portion 63 does not refer to a series of ring-shaped objects, but rather refers to a series of adjacent copper particles CP, such as spherical ones. The chain-like portion 63 is continuously connected from the outer surface 21 of the element body 20 to the outer surface 65 of the first base electrode 61A opposite the element body 20. Furthermore, in the chain-like portion 63, a plurality of copper particles CP are connected over a length of 100 nm or more in a direction along the outer surface 21 of the element body 20. In this embodiment, substantially the entire copper component of the first base electrode 61A is the chain-like portion 63. When the first base electrode 61A is viewed in cross section perpendicular to the outer surface 21 of the element body 20, the proportion of the area occupied by the copper particles CP to the entire area of ​​the cross section is 50% or more and 95% or less. Furthermore, in the cross-sectional view, the first base electrode 61A has multiple gaps G between different portions of the chain-like portion 63. The ratio of the area occupied by the gaps G to the total area of ​​the cross section is 5% or more and 50% or less. Therefore, the chain-like portion 63 of the first base electrode 61A has a spongy structure and has gaps G as continuous pores therein. Note that the "gaps G between different portions of the chain-like portion 63" is a concept that includes not only gaps G between different portions within one chain-like portion 63 but also gaps G between each portion of multiple different chain-like portions 63. Furthermore, it is not necessary for gaps G to exist between all of the chain-like portions 63.

[0031] The filler 64 contained in the first base electrode 61A fills the gaps G. In this embodiment, substantially all of the gaps G are filled with the filler 64. Therefore, when the first base electrode 61A is viewed in cross section perpendicular to the outer surface 21 of the element body 20, the filler 64 fills multiple gaps G. The proportion of the area occupied by the filler 64 to the entire area of ​​the cross section is 5% or more and 50% or less. The filler 64 is a polymer compound containing carbon and nitrogen. Therefore, the elastic modulus of the filler 64 is smaller than the elastic modulus of the chain portion 63. In other words, the filler 64 is softer than the chain portion 63.

[0032] The total area of ​​the cross section of the first base electrode 61A, the area occupied by the copper particles CP, the area occupied by the gaps G, and the area occupied by the filler 64 are calculated by image processing. Specifically, first, the element body 20 is ground in a direction perpendicular to the outer surface 21 by focused ion beam processing or the like. Next, the ground cross section is imaged using a transmission electron microscope (TEM). The imaging range at this time is a range in which the first base electrode 61A is imaged over a distance of 5 μm or more in a direction along the outer surface 65 of the first base electrode 61A. The area of ​​the first base electrode 61A in the image is defined as the "total area of ​​the cross section." The area occupied by the copper particles CP within the range of the image is defined as the "area occupied by the copper particles CP." The value obtained by subtracting the "area occupied by the copper particles CP" from the "total area of ​​the cross section" is defined as the "area occupied by the gaps G." The area occupied by the filler 64 within the range of the image is defined as the "area occupied by the filler 64." Energy dispersive X-ray spectroscopy (EDX) may be used to calculate these areas.

[0033] As shown in FIG. 5 , when the first base electrode 61A is viewed in cross section perpendicular to the outer surface 21 of the element body 20, the longest line segment among the line segments connecting two points on the outer edge of one copper particle CP is defined as the first line segment L1 of the copper particle CP. Of the line segments connecting two points on the outer edge of the copper particle CP, the line segment that passes through the midpoint of the first line segment L1 and is perpendicular to the first line segment L1 is defined as the second line segment L2 of the copper particle CP. In this case, in most of the copper particles CP, the dimension of the first line segment L1 is less than twice the dimension of the second line segment L2. That is, most of the copper particles CP are approximately spherical. And, in at least some of the copper particles CP, the dimension of the first line segment L1 is at least twice the dimension of the second line segment L2. That is, at least some of the copper particles CP are flat.

[0034] Furthermore, the average value of the dimension of the first line segment L1 in the plurality of copper particles CP in contact with the first metal layer 61B is 50 nm or less. In contrast, the average value of the dimension of the first line segment L1 in the plurality of copper particles CP that are not in contact with the first metal layer 61B and are located near the first metal layer 61B is greater than 50 nm. In particular, in some of the copper particles CP that are not in contact with the first metal layer 61B and are located near the first metal layer 61B, the dimension of the first line segment L1 is several hundred nm. The average value of the dimension of the first line segment L1 is calculated by randomly selecting 20 or more copper particles CP from the plurality of copper particles CP that meet the above conditions in the cross-sectional image of the first base electrode 61A.

[0035] Furthermore, the average value of the dimensions of the first line segments L1 in the multiple copper particles CP in contact with the element body 20 is 30 nm or less. Therefore, the dimensions of the first line segments L1 vary among the copper particles CP in contact with the first metal layer 61B, the copper particles CP in contact with the element body 20, and the copper particles CP that do not contact either. Reflecting this variation in the particle size of the copper particles CP, the standard deviation of the dimensions of the first line segments L1 in the multiple copper particles CP in the cross section of the first base electrode 61A is 50 nm or more. Note that this standard deviation is calculated by randomly selecting 50 or more copper particles CP in the cross-sectional image of the first base electrode 61A.

[0036] As described above, the first base electrode 61A has a chain portion 63 formed by a series of copper particles CP of different particle sizes, and the gaps G between the different portions of the chain portion 63 are filled with the filler 64. That is, the first base electrode 61A has a dense structure without voids. Therefore, almost no metal components originating from the first metal layer 61B are diffused into the first base electrode 61A.

[0037] Specifically, as shown in FIG. 4 , a portion of the first base electrode 61A that is separated from the outer surface 65 of the first base electrode 61A by less than 10% of the dimension of the first base electrode 61A in a direction perpendicular to the outer surface 65 of the first base electrode 61A is defined as a surface-side portion 66. A portion of the first base electrode 61A that is separated from the outer surface 65 of the first base electrode 61A by 10% or more of the dimension of the first base electrode 61A in a direction perpendicular to the outer surface 65 of the first base electrode 61A is defined as an inner portion 67. In this case, the surface-side portion 66 contains the same type of metal as the metal contained in the first metal layer 61B. However, the concentration of the metal contained in the surface-side portion 66 is 1 / 10 or less of the concentration of the metal contained in the first metal layer 61B. Furthermore, the inner portion 67 does not contain the same type of metal as the metal contained in the first metal layer 61B. Here, "not containing" means that the concentration of the same type of metal contained in the first base electrode 61A is 1 / 100 or less of the concentration of the metal contained in the first metal layer 61B. As described above, the portion of the first metal layer 61B that is in contact with the first base electrode 61A is a Ni-plated layer. That is, in this embodiment, the "metal" is nickel. The metal concentration is measured by composition analysis using an electron microscope, such as so-called line analysis or point analysis. In this case, the unit of concentration is mole percentage (mol%). In this embodiment, the nickel concentration in the surface side portion 66 of the first base electrode 61A is 10 mol% or less.

[0038] (Manufacturing Method) Next, a description will be given of a manufacturing method of electronic component 10. As shown in Fig. 6, the manufacturing method of electronic component 10 includes a laminate preparation step S11, an R-chamfering processing step S12, a conductor paste preparation step S13, a conductor application step S14, a curing step S15, and a plating step S16.

[0039] First, in the laminate preparation step S11, a laminate is prepared by stacking and firing ceramic sheets that form the element body 20 and conductive pastes that form the internal electrodes. Specifically, first, multiple ceramic sheets are prepared. Next, the multiple sheets and conductive pastes are alternately stacked. That is, the conductive paste is stacked on the ceramic sheets. Another sheet is stacked on the sheet on which the conductive paste is stacked. Another conductive paste is stacked on the sheet. By stacking the conductive paste a total of eight times in this manner, a laminate of ceramic sheets and conductive paste is produced. Next, the laminate is compressed in the stacking direction using a mold press or the like. The compressed laminate is then cut and shaped to a predetermined size. Next, the laminate is fired, whereby the multiple ceramic sheets become the element body 20 of the electronic component 10. Furthermore, the conductive paste sandwiched between the multiple sheets becomes the first internal electrode 41 and second internal electrode 42 of the electronic component 10. In the laminate preparation step S11, a laminate fired in this manner is prepared. At this stage, the laminate has a rectangular parallelepiped shape.

[0040] Next, an R-chamfering process S12 is performed. In the R-chamfering process S12, curved surfaces are formed at the boundary portions between two adjacent flat surfaces 22 of the laminate prepared in the laminate preparation process S11 and at the boundary portions between three adjacent flat surfaces 22. For example, the corners of the laminate are R-chamfered by barrel polishing, thereby forming curved surfaces at the boundary portions.

[0041] Next, a conductor paste preparation step S13 is performed. In the conductor paste preparation step S13, a conductor paste is prepared by adding an amine and a carboxylic acid to a copper-containing solution. Specifically, the conductor paste is prepared as a so-called complex ink. First, a copper-containing metal salt is mixed with an amine as a solvent. In this embodiment, the metal salt is powdered copper formate. The amine as a solvent is, for example, a mixture of "2-ethylhexylamine" and "2-amino-methyl-1-propanol." The mixed solution is stirred for approximately 24 hours using a stirrer such as a magnetic stirrer. This causes the powdered copper formate to form a complex and dissolve in the amine. In other words, a copper-containing solution is prepared.

[0042] Next, an amine and a carboxylic acid are added as additives to the solution after stirring. In this embodiment, the amine as the additive is "N,N-diethyl-p-phenylenediamine (C ２ H ５ ) ２ NC ６ H ４ NH ２ "). Carboxylic acids include hexanoic acid (CH ３ (CH ２ ) ４ The solution containing these additives is then stirred in the same manner as described above. The additives are dispersed in the solution by stirring, producing a conductive paste. In this state, the conductive paste contains particulate copper and a resin component synthesized by the additives.

[0043] Next, the conductor application step S14 is performed. In the conductor application step S14, the conductor paste prepared in the conductor paste preparation step S13 is applied to the element body 20 using a dispenser. The conductor paste is applied to two locations: a portion of the first end face 22A of the element body 20 and a portion of the second end face 22B of the element body 20. Specifically, the conductor paste is applied so as to cover the entire first end face 22A and portions of the four side faces 22C. The conductor paste is also applied so as to cover the entire second end face 22B and portions of the four side faces 22C.

[0044] Next, a curing step S15 is performed. In the curing step S15, the conductive paste is cured to form a first base electrode 61A and a second base electrode 62A on the outer surface 21 of the element body 20. In this embodiment, the element body 20 to which the conductive paste has been applied is heated in a nitrogen atmosphere in which the heating furnace is filled with nitrogen gas, thereby curing the conductive paste. Specifically, the element body 20 to which the conductive paste has been applied is heated at a temperature of 300°C or higher and 1000°C or lower. This causes the conductive paste to be fired.

[0045] Here, the sintering start temperature of the copper contained in the conductor paste is lower than the hardening start temperature of the resin component. Therefore, as the firing temperature increases, sintering of the copper contained in the conductor paste begins first. That is, the copper particles CP in the conductor paste are sintered to form the chain portion 63. At this point, hardening of the resin component has not yet begun. That is, the resin component has fluidity. Therefore, the resin component of the conductor paste fills the gaps G between different parts of the chain portion 63. Then, when the firing temperature increases to the hardening start temperature of the resin component, the resin component begins to harden. In the hardening process S15, the copper component is sintered in this manner to form the chain portion 63 made of the copper particles CP. Next, the resin component fills the gaps G and hardens, forming the filler 64 portion of each base electrode. As a result, the first base electrode 61A and the second base electrode 62A described above are formed.

[0046] Next, a plating step S16 is performed. Electroplating is performed on the first base electrode 61A and the second base electrode 62A. As a result, a first metal layer 61B is formed on the surface of the first base electrode 61A. Furthermore, a second metal layer 62B is formed on the surface of the second base electrode 62A. The first metal layer 61B and the second metal layer 62B are electroplated with two types of metal, nickel and tin, to form a two-layer structure. In this manner, the electronic component 10 is formed.

[0047] (Effects of this embodiment) The effects of this embodiment will be described below. Note that, with regard to effects common to the first base electrode 61A and the second base electrode 62A, the first base electrode 61A will be described as a representative example, and a description of the effects of the second base electrode 62A will be omitted.

[0048] (1) In the above embodiment, the first base electrode 61A has a chain portion 63 formed by a series of copper particles CP. The chain portion 63 is in contact with the outer surface 21 of the element body 20 and the first metal layer 61B. The presence of the chain portion 63 makes it easy for gaps G to form between different portions of the chain portion 63. This makes it easy for the filler 64 to fill the gaps G. Therefore, gaps not filled with the filler 64 are unlikely to form within the first base electrode 61A. This makes it possible to prevent liquids such as plating solution from penetrating into the first base electrode 61A.

[0049] (2) In the above embodiment, the elastic modulus of the filler 64 is smaller than the elastic modulus of the chain portion 63. Therefore, even if stress acts on the first base electrode 61A due to, for example, an external physical impact, the filler 64 can absorb the stress by elastically deforming. As a result, cracks are less likely to occur in the first base electrode 61A.

[0050] (3) In the above embodiment, the area occupied by the copper particles CP in a cross-sectional view of the first base electrode 61A is 50% to 95% of the entire cross-sectional area of ​​the first base electrode 61A. This ratio allows the filler 64 to fill the entire first base electrode 61A while ensuring electrical conductivity through the copper particles CP.

[0051] (4) In the above embodiment, the arithmetic mean roughness of the outer surface 65 of the first base electrode 61A is 0.5 μm or more. This increases the adhesive strength between the first metal layer 61B and the first base electrode 61A due to the so-called anchor effect. Therefore, the first metal layer 61B is less likely to peel off from the first base electrode 61A.

[0052] (5) In the above embodiment, at least some of the copper particles CP are flat. Flat copper particles CP come into contact with more other copper particles CP than spherical copper particles CP. Therefore, a chain portion 63 in which copper particles CP are connected is easily formed. Furthermore, contact with more copper particles CP increases the cross-sectional area of ​​the chain portion 63, which serves as an electron conduction path. In other words, a decrease in the electrical resistance of the entire first base electrode 61A can be expected compared to, for example, when the chain portion 63 is composed only of approximately spherical copper particles CP.

[0053] (6) In the above embodiment, the average dimension of the first line segment L1 of the copper particles CP in contact with the first metal layer 61B is 50 nm or less. Because the particle diameter of the copper particles CP closest to the first metal layer 61B is sufficiently small, the total surface area of ​​each copper particle CP at the interface between the first metal layer 61B and the first base electrode 61A is large. Therefore, the anchor effect increases the strength of adhesion between the first metal layer 61B and the first base electrode 61A.

[0054] (7) In the above embodiment, the standard deviation of the dimensions of the first line segments L1 among the multiple copper particles CP is 50 nm or more. That is, there is considerable variation in the particle sizes of the copper particles CP. As a result, copper particles CP with small particle sizes tend to enter the gaps between other copper particles CP. Therefore, multiple copper particles CP tend to come into contact with each other, and the chain-like portions 63 tend to spread over a wide area. By spreading the chain-like portions 63 widely, the electrical conduction path within the first base electrode 61A is less likely to be interrupted.

[0055] (8) In the above embodiment, the inner portion 67 of the first base electrode 61A does not contain the same type of metal as the metal contained in the first metal layer 61B. Furthermore, the surface side portion 66 of the first base electrode 61A contains the same type of metal as the metal contained in the first metal layer 61B, but the concentration of the metal is 1 / 10 or less of the concentration of the metal in the first metal layer 61B. In other words, the metal component of the first metal layer 61B hardly diffuses into the first base electrode 61A. If the metal penetrates into the inner portion 67 of the first base electrode 61A, the electrical resistance value is likely to increase. This configuration prevents such a situation.

[0056] (9) In the above embodiment, the first metal layer 61B contains one or more metals selected from copper, nickel, silver, tin, palladium, and gold. At least such metals can significantly suppress the diffusion of the metal from the first metal layer 61B into the first base electrode 61A.

[0057] (10) In the above embodiment, the filler 64 is a compound containing carbon and nitrogen. This makes it easy for the elastic modulus of the filler 64 to be smaller than the elastic modulus of the copper particles CP. Therefore, even if external stress is applied, the filler 64 easily absorbs the stress by elastically deforming.

[0058] (11) In the above embodiment, the conductive paste is prepared by adding an amine and a carboxylic acid to a copper-containing solution in the conductive paste preparation step S13. By preparing the conductive paste in this manner, the chain portion 63 is easily formed on each base electrode in the hardening step S15.

[0059] (12) In the above embodiment, in the curing step S15, first, the copper component of the conductive paste is fired to form a chain portion 63 made of copper particles CP. Then, the resin component of the conductive paste is fired. At this time, the resin component shrinks due to firing. The chain portion 63 then stretches or deforms as the copper particles CP shift position due to the shrinkage of the surrounding resin component. In other words, even if the resin component shrinks, the chain portion 63 is unlikely to be interrupted. Therefore, the electrical conductivity of the base electrode is unlikely to be impaired. In particular, the base electrode is likely to become thinner at the edge of the side surface 22C of the element body 20 due to firing, but according to this configuration, electrical conductivity is unlikely to be impaired even in such areas.

[0060] <Modifications> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0061] The electronic component 10 is not limited to a multilayer ceramic capacitor. For example, the electronic component 10 may be a piezoelectric component, a thermistor, an inductor, or the like, which includes the element body 20, the first external electrode 61, and the second external electrode 62.

[0062] The material of the element 20 may be a dielectric, a piezoelectric, a magnetic material such as ferrite, or a composite of a filler and a metal. The conductive paste may be nanoink. In the case of nanoink, nanometal powder containing copper particles is dispersed in a solvent containing cellosolves, carbitols, hydrocarbons, aromatics, or the like. Then, an amine and a carboxylic acid are added as additives to produce a conductive paste.

[0063] When the conductive paste is a complex ink, the amine and carboxylic acid used as the additive are not limited to those in the above embodiment. Examples of the amine used as the additive include "N,N-dimethyl-1,3-propanediamine," "1,2-propanediamine," "m-xylene-α,α'-diamine," "N,N,N',N'-tetramethyl-p-phenylenediamine," "N,N-dibutyl-1,3-propanediamine," "p-phenylenediamine," "ethylenediamine," "N,N-dimethylethylenediamine," "N,N,N',N'-tetramethylethylenediamine," and "1,4-butanediamine." , "N,N,N',N'-tetramethyl-1,6-hexanediamine," "hexamethylenediamine," "1,5-naphthalenediamine," "1,12-dodecanediamine," "1,8-octanediamine," "o-phenylenediamine," "m-phenylenediamine," "N,N'-dimethylethylenediamine," "4-methyl-1,2-phenylenediamine," "1,3-propanediamine," and "N,N-diethyl-1,3-propanediamine." The carboxylic acid may be, for example, formic acid, acetic acid, propionic acid, butanoic acid, heptanoic acid, valeric acid, octanoic acid, decanoic acid, and the like.

[0064] The number of first internal electrodes 41 and second internal electrodes 42 is not limited to the example in the above embodiment. The number of first internal electrodes 41 may be more or less than four. The same applies to the second internal electrodes 42.

[0065] When the first base electrode 61A is viewed in cross section perpendicular to the outer surface 21 of the element body 20, the proportion of the area occupied by the copper particles CP to the total area of ​​the cross section may be less than 50% or more than 95%. Even in such a case, by filling the gaps G with the filler 64, it is possible to prevent the penetration of liquid into the base electrode.

[0066] The arithmetic mean roughness of the outer surface 65 of the first base electrode 61A may be less than 0.5 μm. Even in this case, at least the effect described in (1) above can be obtained. The same applies to the second base electrode 62A.

[0067] The copper particles CP do not have to include flat particles. That is, in all copper particles CP, the dimension of the first line segment L1 may be less than twice the dimension of the second line segment L2. Furthermore, the average dimension of the first line segment L1 of the multiple copper particles CP in contact with each metal layer may be greater than 50 nm. Regardless of the shape and size of the copper particles CP, it is sufficient that the base electrode has the chain portion 63.

[0068] The inner portion 67 of the first base electrode 61A may contain the same type of metal as the first metal layer 61B. However, the concentration of the metal contained in the inner portion 67 is preferably 1 / 10 or less of the concentration of the metal contained in the first metal layer 61B. This also applies to the second base electrode 62A.

[0069] The concentration of the metal contained in the surface side portion 66 of the first base electrode 61A may be more than 1 / 10 of the concentration of the metal contained in the first metal layer 61B. Even in such a case, it is sufficient that the concentration of the metal in the inner portion 67 is low. This also applies to the second base electrode 62A.

[0070] The method for measuring the metal concentration is not limited to the example of the above embodiment. For example, measurement may be performed using EDX. Specifically, in this method, the element body 20 is first ground in a direction perpendicular to the outer surface 21 using focused ion beam processing or the like. Next, an electron beam is irradiated onto the ground cross section of the element body 20 using a TEM. The electron beam is irradiated over a range of 1 μm or more along the outer surface 65 of the first base electrode 61A. Mapping data of the composition in the cross section is obtained by measuring the dose of characteristic X-rays generated during this process. This mapping data is in the form of an image. In the mapping data, the higher the dose of characteristic X-rays, the higher the brightness value in the image. That is, in the mapping data, the higher the amount of composition, the higher the brightness value in the image. Therefore, the concentration of the composition in a specific region of this mapping data is calculated by dividing the sum of the brightness values ​​present in that region by the area of ​​that region. In this case, the concentration is expressed as an average brightness value per unit area. In this manner, the nickel concentration in the first metal layer 61B, the concentration in the surface portion 66, and the concentration in the inner portion 67 may be measured and compared. The concentration may be expressed in units of mole percentage (mol%), mass percent (wt%), or the like.

[0071] The material of the filler 64 is not limited to the example in the above embodiment. For example, the filler 64 may be a synthetic resin. Furthermore, the filler 64 does not have to be a polymer compound and may be made of carbon only. Furthermore, the filler 64 does not have to contain carbon or nitrogen. For example, the filler 64 may be a silicone resin.

[0072] The electronic component 10 may include a glass film. In this case, for example, the glass film may be formed so as to cover a partial region of the outer surface 21 of the element body 20. In other words, even if a glass film covering the element body 20 is present, it is sufficient that the electrical connection between the first internal electrode 41 and the first external electrode 61, and the electrical connection between the second internal electrode 42 and the second external electrode 62 are ensured.

[0073] In the conductor application step S14, the method for applying the conductor paste to the outer surface 21 of the element body 20 is not limited to the example in the above embodiment. For example, the conductor paste may be printed on the outer surface 21 of the element body 20 by a so-called inkjet method, a screen printing method, or the like.

[0074] In the hardening step S15, firing may be performed in multiple stages. For example, when firing is performed in two stages, the element body 20 may first be fired at a temperature of 200° C. to 400° C. for a predetermined time. Next, the element body 20 may be removed from the heating furnace and subjected to a predetermined operation, and then the element body 20 may be fired at a temperature of 300° C. to 1000° C.

[0075] The difference between the sintering start temperature of the copper component of the conductive paste and the hardening start temperature of the filler 64 may vary depending on the material of the filler 64. In order to keep the copper component contained in the conductive paste in a particulate state, it is preferable to use a filler 64 made of a material that ensures the difference in the above-mentioned start temperatures is 100 degrees or less.

[0076] The sintering temperature of the copper contained in the conductive paste may be equal to or higher than the hardening temperature of the resin component. By sintering the copper in the same process as hardening the resin component, the filler 64 can be filled between the copper particles CP, i.e., between different portions of the chain-like portion 63.

[0077] <Supplementary Notes> The technical ideas that can be understood from the above embodiments and modified examples will be described below. [1] An electronic component comprising an element body and an external electrode covering an outer surface of the element body, the external electrode having a base electrode, the base electrode including a plurality of copper particles and a filler, the base electrode having a portion where the plurality of copper particles are continuously connected from the outer surface of the element body to an outer surface of the base electrode opposite the element body, and a chain portion where the plurality of copper particles are connected over a length of 100 nm or more in a direction along the outer surface of the element body, when viewed in a cross section perpendicular to the outer surface of the element body, there are gaps between different portions of the chain portion, and the filler is filled in the gaps.

[0078] [2] An electronic component according to [1], wherein when the base electrode is viewed in cross section perpendicular to the outer surface of the body, the proportion of the area occupied by the copper particles to the total area of ​​the cross section is 50% or more and 95% or less.

[0079] [3] The electronic component according to [1] or [2], wherein, when the base electrode is viewed in cross section perpendicular to the outer surface of the element body, the longest line segment connecting two points on the outer edge of one of the copper particles is defined as a first line segment of the copper particle, and the line segment passing through the midpoint of the first line segment and perpendicular to the first line segment is defined as a second line segment of the copper particle, and in at least some of the copper particles, the dimension of the first line segment is at least twice the dimension of the second line segment.

[0080] [5] An electronic component described in any one of [1] to [4], wherein the external electrode has a metal layer covering the outer surface of the base electrode, and when the base electrode is viewed in cross section perpendicular to the outer surface of the body, when the longest line segment connecting two points on the outer edge of one of the copper particles is defined as the first line segment of the copper particle, the average value of the dimensions of the first line segments of multiple copper particles in contact with the metal layer is 50 nm or less.

[0081] [6] An electronic component described in any one of [1] to [5], wherein when the base electrode is viewed in cross section perpendicular to the outer surface of the body, the longest line segment connecting two points on the outer edge of one of the copper particles is defined as the first line segment of the copper particle, and the standard deviation of the dimensions of the first line segments in multiple of the copper particles is 50 nm or more.

[0082] [7] An electronic component described in any one of [1] to [6], wherein the external electrode has a metal layer covering the outer surface of the base electrode, and an inner portion of the base electrode that is at least 10% of the dimension of the base electrode away from the outer surface of the base electrode in a direction perpendicular to the outer surface of the base electrode does not contain the same type of metal as the metal contained in the metal layer.

[0083] [8] An electronic component according to any one of [1] to [7], wherein the external electrode has a metal layer covering the outer surface of the base electrode, and a surface portion of the base electrode that is less than 10% of the dimension of the base electrode in a direction perpendicular to the outer surface of the base electrode from the outer surface of the base electrode contains the same type of metal as the metal contained in the metal layer, and the concentration of the metal contained in the surface portion is 1 / 10 or less of the concentration of the metal contained in the metal layer.

[0084] [9] The electronic component according to any one of [1] to [8], wherein the external electrode has a metal layer covering the outer surface of the base electrode, and the metal layer contains one or more metals selected from copper, nickel, silver, tin, palladium, and gold.

[0085]

[10] An electronic component according to any one of [1] to [9], wherein the filler contains carbon.

[11] An electronic component according to

[10] , wherein the filler contains nitrogen.

[12] A method for manufacturing an electronic component, comprising: a laminate preparation step of preparing an element body; a conductor paste preparation step of preparing a conductor paste in which an amine and a carboxylic acid are added to a copper-containing solution; a conductor application step of applying the conductor paste to the outer surface of the element body; and a curing step of hardening the conductor paste to form a base electrode on the outer surface of the element body.

[0086] REFERENCE SIGNS LIST 10...Electronic component 20...Element body 21...Outer surface 61...First external electrode 61A...First base electrode 61B...First metal layer 62...Second external electrode 62A...Second base electrode 62B...Second metal layer CP...Copper particle L1...First line segment L2...Second line segment 63...Chain portion 64...Filler 65...Outer surface G...Gap

Claims

1. An electronic component comprising a base body and an external electrode covering the outer surface of the base body, the external electrode having a base electrode, the base electrode including a plurality of copper particles and a filler, the base electrode being a portion where the plurality of copper particles are continuously connected from the outer surface of the base body to the outer surface of the base electrode opposite to the base body, and having a chain-like portion where the plurality of copper particles are continuously connected over 100 nm or more in a direction along the outer surface of the base body, having a gap between different portions of the chain-like portion when viewed in cross-section in a cross-section orthogonal to the outer surface of the base body, and the filler being filled in the gap.

2. The electronic component according to claim 1, wherein when the base electrode is viewed in cross-section in a cross-section orthogonal to the outer surface of the base body, the ratio of the area occupied by the copper particles in the entire area of the cross-section is 50% or more and 95% or less.

3. The electronic component according to claim 1 or claim 2, wherein the arithmetic mean roughness of the outer surface of the base electrode is 0.5 μm or more.

4. When the base electrode is viewed in cross-section in a cross-section orthogonal to the outer surface of the base body, among the line segments connecting two points on the outer edge of one of the copper particles, the longest line segment is defined as the first line segment of the copper particle, and the line segment passing through the midpoint of the first line segment and orthogonal to the first line segment is defined as the second line segment of the copper particle. For at least some of the plurality of copper particles, the dimension of the first line segment is 2 times or more the dimension of the second line segment. The electronic component according to any one of claims 1 to 3.

5. The external electrode has a metal layer covering the outer surface of the base electrode. When the base electrode is viewed in cross-section in a cross-section orthogonal to the outer surface of the base body, among the line segments connecting two points on the outer edge of one of the copper particles, the longest line segment is defined as the first line segment of the copper particle. The average value of the dimensions of the first line segments of the plurality of copper particles in contact with the metal layer is 50 nm or less. The electronic component according to any one of claims 1 to 4.

6. When the base electrode is viewed in cross-section in a cross-section orthogonal to the outer surface of the base body, among the line segments connecting two points on the outer edge of one of the copper particles, the longest line segment is defined as the first line segment of the copper particle. The standard deviation of the dimensions of the first line segments of the plurality of copper particles is 50 nm or more. The electronic component according to any one of claims 1 to 5.

7. The external electrode has a metal layer covering the outer surface of the base electrode. Among the base electrodes, an inner portion that is 10% or more away from the outer surface of the base electrode in a direction orthogonal to the outer surface of the base electrode does not contain the same type of metal as the metal contained in the metal layer. The electronic component according to any one of claims 1 to 6.

8. The external electrode has a metal layer covering the outer surface of the base electrode. Among the base electrodes, a surface-side portion that is less than 10% of the dimension of the base electrode in a direction orthogonal to the outer surface of the base electrode contains the same type of metal as the metal contained in the metal layer. The concentration of the metal contained in the surface-side portion is 1 / 10 or less with respect to the concentration of the metal contained in the metal layer. The electronic component according to any one of claims 1 to 7.

9. The external electrode has a metal layer covering the outer surface of the base electrode. The metal layer contains one or more metals selected from copper, nickel, silver, tin, palladium, and gold. The electronic component according to any one of claims 1 to 8.

10. The filler contains carbon. The electronic component according to any one of claims 1 to 9.

11. The filler contains nitrogen. The electronic component according to claim 10.

12. A method for manufacturing an electronic component, comprising: a laminate preparation step of preparing a body; a conductor paste preparation step of preparing a conductor paste in which an amine and a carboxylic acid are added to a solution containing copper; a conductor application step of applying the conductor paste to the outer surface of the body; and a curing step of curing the conductor paste to form a base electrode on the outer surface of the body.

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