Electronic component

Abstract

This electronic component comprises: an element body (20); and a first external electrode (61) that covers a part of an outer surface (21) of the element body (20). The first external electrode (61) does not contain a silver component. The first external electrode (61) has a first base electrode (61A) that covers the outer surface (21) of the element body (20). The first base electrode (61A) contains copper particles (63) and a silicone (64) as a synthetic resin. If the first base electrode (61A) is divided into equal halves, specifically into a first portion (P1) that is positioned on the element body (20) side and a second portion (P2) that is positioned on the opposite side from the element body (20), the average value of the particle diameters of the copper particles (63) in the second portion (P2) is greater than the average value of the particle diameters of the copper particles (63) in the first portion (P1).

Description

Electronic Components

[0001] The present disclosure relates to electronic components.

[0002] The electronic component described 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 include a first electrode, a second electrode, and a third electrode. The first electrode covers a portion of the outer surface of the element body. The first electrode is mainly composed of Cu. The second electrode covers the outer surface of the first electrode. The second electrode is mainly composed of Ag—Pd. The third electrode covers the outer surface of the second electrode. The third electrode is mainly composed of Ag and a synthetic resin.

[0003] Japanese Patent Application Laid-Open No. 2006-229077

[0004] The electronic component described in Patent Document 1 is subject to external mechanical shock or thermal shock due to temperature change. This can cause cracks or the like in the element body of the electronic component. In the electronic component described in Patent Document 1, the third electrode contains a synthetic resin, and the resin component can suppress impacts on the element body. However, the silver component of the third electrode is prone to elution in high-temperature, high-humidity environments. Therefore, the eluted silver component may come into contact with the element body and cause migration. Therefore, a technology is needed that suppresses impacts on the element body while suppressing migration.

[0005] In order to solve the above problem, one aspect of the present disclosure is an electronic component comprising: an element body; and an external electrode covering a portion of the outer surface of the element body and containing no silver components, wherein the external electrode has a base electrode covering the outer surface of the element body, the base electrode containing copper particles and a synthetic resin, and when the base electrode is divided into two equal parts, a first part located on the element body side and a second part located on the opposite side of the element body, the average particle size of the copper particles in the second part is larger than the average particle size of the copper particles in the first part.

[0006] In the above configuration, the external electrode does not contain silver. Therefore, with this configuration, migration can be suppressed compared to when the external electrode contains silver. On the other hand, since the particle size of the copper particles in the second portion is relatively large, the occurrence of cracks and the like in the element body can also be suppressed.

[0007] 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 taken along line 3-3 in FIG. 2. FIG. 4 is a schematic diagram of a cross-section of a first external electrode of the electronic component. FIG. 5 is an enlarged view of a first base electrode of the electronic component. FIG. 6 is a schematic diagram of copper particles in a specific cross-section of the first base electrode of the electronic component. FIG. 7 is a flowchart illustrating a method for manufacturing an electronic component.

[0008] An embodiment of an electronic component will now be described with reference to the drawings. The drawings may show components enlarged for ease of understanding. The dimensional proportions of the components may differ from those in the actual components or from those in other drawings.

[0009] <Regarding 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. In addition, 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.

[0010] The outer surface 21 of the element body 20 has six flat surfaces. The term "surface" of the element body 20 used here refers to a surface that can be observed as a surface 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, the surface is still referred to as a flat or curved surface. The six flat surfaces face in different directions. The six flat surfaces 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.

[0011] The boundary portions between two adjacent flat surfaces and the boundary portions between three adjacent flat surfaces of the outer surface 21 of the element body 20 are curved surfaces. That is, the corners of the element body 20 are rounded and chamfered.

[0012] 1 and 2, the element body 20 has a dimension along the first axis X that is larger than the dimensions along the third axis Z and the dimensions along the second axis Y. 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, a rare earth compound, or the like.

[0013] 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 located inside the element body 20.

[0014] The material of the first internal electrode 41 is a conductive material. For example, the material of the first internal electrode 41 is Ni. The material of the first internal electrode 41 may further include a metal such as Ni, Cu, Ag, Au, Pt, Sn, or Pd, or an alloy containing these metals. The material of the second internal electrode 42 is the same as the material of the first internal electrode 41.

[0015] 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.

[0016] 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 the same as those of the first internal electrode 41.

[0017] 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, a total of eight internal electrodes are arranged alternately in the order of the first internal electrodes 41 and the second internal electrodes 42 from the side surface 22C facing the second positive direction Y1 toward the second negative direction Y2. In this embodiment, the distances between the respective internal electrodes in the direction along the second axis Y are equal.

[0018] As shown in FIG. 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 located closer to the first positive direction X1. The second internal electrodes 42 are located closer to the first negative direction X2. Specifically, the ends of the first internal electrodes 41 on the first positive direction X1 side substantially coincide with the ends of the element body 20 on the first positive direction X1 side. Therefore, the ends of the first internal electrodes 41 on the first positive direction X1 side are exposed from the first end surface 22A of the element body 20. The ends of the first internal electrodes 41 on the first negative direction X2 side are located inside the element body 20 and do not reach the end of the element body 20 on the first negative direction X2 side.

[0019] On the other hand, the end of the second internal electrode 42 on the first negative direction X2 side substantially 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 from the second end face 22B of the element body 20. 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.

[0020] As shown in FIG. 3 , the electronic component 10 includes a first external electrode 61 and a second external electrode 62. The first external electrode 61 and the second external electrode 62 are conductive as a whole. However, the first external electrode 61 and the second external electrode 62 do not contain silver. Here, "does not contain silver" means that a small amount of silver may be mixed into each external electrode during the manufacturing process. For example, if the atomic percentage of silver atoms relative to the total atoms constituting each external electrode is less than 1 atm %, the "external electrode does not contain silver." This is because, if the atomic percentage of silver atoms is less than 1 atm %, significant migration that would affect the characteristics of the electronic component 10 does not occur.

[0021] The first external electrode 61 has a first base electrode 61A, a first mixed layer 61B, and a first metal layer 61C. The first mixed layer 61B is indicated by a bold line in FIG. 3 . The first base electrode 61A covers a portion of the outer surface 21 of the element body 20, including the first end face 22A. The first base electrode 61A is a five-sided electrode that covers the first end face 22A of the element body 20 and portions of the four side faces 22C facing the first positive direction X1. In this embodiment, the first base electrode 61A is made of copper and glass. The first base electrode 61A is a sintered body. Details of the first base electrode 61A will be described later.

[0022] The first metal layer 61C covers the outer surface BD61A of the first base electrode 61A. A portion of the first metal layer 61C protrudes from the first base electrode 61A. Although not shown, the first metal layer 61C has a two-layer structure including, in this order from the first mixed layer 61B side, a nickel layer and a tin layer.

[0023] The first mixed layer 61B is located between the first base electrode 61A and the first metal layer 61C. In other words, the first metal layer 61C covers the outer surface BD61A of the first base electrode 61A via the first mixed layer 61B. Details of the first mixed layer 61B will be described later.

[0024] The second external electrode 62 includes a second base electrode 62A, a second mixed layer 62B, and a second metal layer 62C. In FIG. 3 , the second mixed layer 62B is indicated by a bold line. The second base electrode 62A covers a portion of the outer surface 21 of the element body 20, including the second end face 22B. The second base electrode 62A is a five-sided electrode that 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 second base electrode 62A is made of the same material as the first external electrode 61, that is, copper and glass. Like the first base electrode 61A, the second base electrode 62A is a sintered body. Details of the second base electrode 62A will be described later.

[0025] The second metal layer 62C covers the outer surface BD62A of the second base electrode 62A. A portion of the second metal layer 62C protrudes from the second base electrode 62A. Although not shown, the second metal layer 62C has a two-layer structure, similar to the first metal layer 61C, including, in order from the second mixed layer 62B side, a nickel layer and a tin layer.

[0026] The second mixed layer 62B is located between the second base electrode 62A and the second metal layer 62C. In other words, the second metal layer 62C covers the outer surface BD62A of the second base electrode 62A via the second mixed layer 62B. Details of the second mixed layer 62B will be described later.

[0027] 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. 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. In FIGS. 1 to 3, the first external electrode 61 and the second external electrode 62 are shown by two-dot chain lines.

[0028] <Configuration of First Base Electrode and Second Base Electrode> The following description will be given focusing on the first base electrode 61A, but the same applies to the second base electrode 62A. The first base electrode 61A contains copper and silicon.

[0029] As shown in Fig. 5, at least a portion of the copper in the first base electrode 61A is spherical copper particles 63. Note that in Fig. 5, only some of the copper particles 63 are labeled with reference numerals. Also, in Fig. 5, each copper particle 63 is illustrated as being approximately circular, but it may be an elliptical or other irregularly shaped particle.

[0030] Furthermore, silicon in the first base electrode 61A exists as a silicone resin 64. The silicone resin 64 is a polymer made up of a siloxane bond and a Si—C bond.

[0031] As shown in FIG. 4 , the average thickness H of the first base electrode 61A is approximately 700 nm. The thickness H of the first base electrode 61A is the shortest distance from the outer surface BD61A of the first base electrode 61A to the outer surface 21 of the element body 20. Note that FIG. 4 illustrates the thickness H at an arbitrary location. Also, in FIG. 4 , the copper particles 63 and silicone resin 64 in the first base electrode 61A are omitted from the illustration, and the first base electrode 61A is illustrated as an integrated body. The average thickness H of the first base electrode 61A is calculated as follows. First, an arbitrary cross section of the first base electrode 61A is photographed using an electron microscope. Next, a range in the photographed image in the direction along the outer surface BD61A of the first base electrode 61A is identified. Within this range, the cross-sectional area of ​​the first base electrode 61A is calculated by image processing for a measurement range of at least 5 μm or more. The average thickness H of the first base electrode 61A is then calculated by dividing the calculated cross-sectional area of ​​the first base electrode 61A in the measurement range by the length of the measurement range. The outer surface BD61A of the first base electrode 61A is defined as the boundary where chemical components contained only in the first metal layer 61C are no longer observed. In the above cross section, the outer surface BD61A of the first base electrode 61A roughly coincides with the interface following the edge of the copper particle 63 on the first metal layer 61C side.

[0032] Here, it is assumed that the first base electrode 61A is divided into a first portion P1 located on the element body 20 side of the first base electrode 61A, and a second portion P2 located on the opposite side of the element body 20. The position where the first base electrode 61A is divided into two is the point where the average value of the thickness H of the first base electrode 61A is divided into two equal parts. In this embodiment, the first portion P1 is in a range of approximately 350 nm from the outer surface 21 of the element body 20 toward the outer surface BD61A of the first base electrode 61A.

[0033] The first base electrode 61A has gaps PA between the copper particles 63, where no synthetic resin such as silicone resin 64 is present. The proportion of gaps PA in the second portion P2 is greater than the proportion of gaps PA in the first portion P1. In particular, throughout the first base electrode 61A, the gaps PA are more numerous near the outer surface BD61A of the first base electrode 61A. Note that the gaps PA are illustrated schematically in FIG. 4.

[0034] The proportion of voids PA in the second portion P2 and the proportion of voids PA in the first portion P1 are determined by the porosity measured as follows. First, the first portion P1 is observed in a square area with sides of 500 nm using a transmission electron microscope at a magnification of 200,000 or more. Within this area, the total area of ​​the voids PA, i.e., the areas without copper particles 63 and silicone resin 64, is calculated by image processing. The porosity is then calculated from the area ratio between the total area of ​​the voids PA and the observed area. This process is repeated at four locations in the first portion P1, and the average value of the porosity in each area is taken as the proportion of voids PA in the first portion P1. Similarly, the proportion of voids PA in the second portion P2 is calculated.

[0035] As shown in FIG. 5 , the average particle size of the copper particles 63 differs between the first portion P1 and the second portion P2. Specifically, the average particle size of the copper particles 63 in the first portion P1 is smaller than the average particle size of the copper particles 63 in the second portion P2. Specifically, the average particle size of the copper particles 63 in the first portion P1 is 75 nm or less. Furthermore, the average particle size of the copper particles 63 in the second portion P2 is 100 nm or more. Therefore, the ratio of the average particle size of the copper particles 63 in the second portion P2 to the average particle size of the copper particles 63 in the first portion P1 is 1.2 or more. Furthermore, throughout the first base electrode 61A as a whole, the particle size of the copper particles 63 decreases toward the element body 20 within the first base electrode 61A.

[0036] The average particle size of the copper particles 63 in the first portion P1 is determined as follows. First, an electron microscope is used to acquire an image of the first base electrode 61A at a magnification range that includes the outer surface BD61A of the first base electrode 61A and the boundary on the outer surface 21 side of the element body 20. Then, in the image, a portion of the first portion P1 that does not include the boundary with the outer surface 21 of the element body 20 or the position that bisects the first base electrode 61A is enlarged, and the outlines of the copper particles 63 are acquired by image processing. The area of ​​one copper particle 63 is then calculated. A circle having the calculated area is then assumed. The diameter of the circle is calculated as the particle size of the copper particle 63. Then, particle sizes are calculated for five or more copper particles 63, and the average value is calculated. In this way, the average particle size of the copper particles 63 is calculated for five or more images, and the average value of the average values ​​acquired from these five images is set as the average particle size of the copper particles 63 in the first portion P1. Similarly, the average particle size of the copper particles 63 in the second portion P2 is calculated.

[0037] As shown in Fig. 6, the first base electrode 61A is viewed in a specific cross section perpendicular to the outer surface BD61A. In the specific cross section, at least some of the copper particles 63 have an elliptical shape. Note that in Fig. 6, only some of the copper particles 63 are labeled with reference numerals.

[0038] In a specific cross section, the flattening ratio of the elliptical copper particle 63 is 0.5 or less. The flattening ratio is calculated as follows. First, the outline of the copper particle 63 is obtained by image processing using an electron microscope. The obtained image is analyzed, and half the length of the longest line segment connecting the edges of one copper particle 63 is defined as the major axis. Furthermore, half the length of the line segment connecting the edges of the copper particle 63, which is perpendicular to the major axis, is defined as the minor axis. When the major axis is a, the minor axis is b, and the flattening ratio is F, the flattening ratio is calculated based on the following formula 1: F = 1 - (b / a) (Formula 1) Furthermore, in the elliptical copper particle 63, the axis along the major axis is defined as the major axis V1. Furthermore, the axis along the minor axis is defined as the minor axis V2 of the copper particle 63. In the specific cross section, the acute angle Q between the major axis V1 of the elliptical copper particle 63 and the axis L along the outer surface BD61A of the first base electrode 61A is 45 degrees or less. That is, the elliptical copper particle 63 is positioned such that the major axis V1 as a whole is aligned with the outer surface BD61A of the first base electrode 61A. The axis L along the outer surface BD61A of the first base electrode 61A is determined as follows: For the image acquired in the specific cross section, an approximate line is drawn to the outer surface BD61A of the first base electrode 61A. The approximate line can be determined, for example, by the least squares method. The axis along this approximate line is then determined as the axis L along the outer surface BD61A of the first base electrode 61A.

[0039] <Regarding Mixed Layer> The first mixed layer 61B and the second mixed layer 62B will be described. Note that, although the first mixed layer 61B will be described below as a representative, the same applies to the second mixed layer 62B.

[0040] 4, the first mixed layer 61B is located between the first base electrode 61A and the first metal layer 61C. Although the boundaries between the first base electrode 61A, the first mixed layer 61B, and the first metal layer 61C are virtually illustrated by solid lines, the boundaries may not be clearly visible.

[0041] The first mixed layer 61B is sufficiently smaller than the thickness H of the first base electrode 61A. For example, the thickness of the first mixed layer 61B is 10% or less of the thickness H of the first base electrode 61A. The first mixed layer 61B contains a chemical component that is not contained in the first base electrode 61A but is contained in the first metal layer 61C. Specifically, the chemical component is a nickel component that is a component of the first metal layer 61C. The first mixed layer 61B also contains a chemical component that is not contained in the first metal layer 61C but is contained in the first base electrode 61A. Specifically, the chemical components are a copper component and a silicone component that are components of the first base electrode 61A. In this embodiment, the components of the first mixed layer 61B do not include any components other than the components of the first base electrode 61A and the components of the first metal layer 61C. That is, the first mixed layer 61B is a layer formed by mixing the first base electrode 61A and the first metal layer 61C.

[0042] <Method for Manufacturing Electronic Component> Next, a description will be given of a method for manufacturing electronic component 10. As shown in Fig. 7 , the method for manufacturing electronic component 10 includes a laminate preparation step S11, an R-chamfering processing step S12, a conductor application step S13, a curing step S14, and a plating step S15.

[0043] First, in forming the element body 20, a laminate is prepared in the laminate preparation step S11. The laminate at this stage is in a state before R-chamfering and is a rectangular parallelepiped with six flat surfaces. Specifically, for example, a plurality of ceramic sheets that will become the element body 20 are prepared. The sheets are thin plates. A conductive paste that will become the first internal electrode 41 is laminated on the sheets. A ceramic sheet that will become the element body 20 is laminated on the paste. A conductive paste that will become the second internal electrode 42 is laminated on the sheets. In this manner, the ceramic sheets and the conductive paste are laminated alternately. The laminated sheets are then compressed in the stacking direction using a mold press or other means. The compressed sheet is then cut to a predetermined size to form an unfired laminate. The unfired laminate is then fired at a high temperature to prepare the laminate.

[0044] Next, an R-chamfering process step S12 is performed. In the R-chamfering process step S12, the laminate prepared in the laminate preparation process S11 is R-chamfered. This process provides an element body 20 with R-chamfered corners.

[0045] Next, a conductor application step S13 is performed. In the conductor application step S13, a conductor paste is applied by a dip method 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. The conductor paste contains a copper component and a silicon component.

[0046] The conductor paste is a complex ink. The conductor paste of the complex ink is prepared as follows: First, an amine compound such as 2-ethylhexylamine is mixed with an alcohol amine such as 2-amino-2-methylpropanol. Then, a silicon component such as silicone resin is added in an amount of 0.001-10 wt % relative to the weight of Cu alone. Then, a metal salt is further added and dissolved to prepare the conductor paste. In other words, the conductor paste contains a copper component and a silicon component. The sintering start temperature of the copper component is 170°C, and the hardening start temperature of the silicon component is 250°C.

[0047] Next, a curing step S14 is performed. Specifically, in the curing step S14, the element body 20 to which the conductive paste has been applied is heated. In this embodiment, the element body 20 to which the conductive paste has been applied is heated in a nitrogen atmosphere. In the curing step S14, the heating is performed in two stages. In the first stage, the temperature of the nitrogen atmosphere is maintained within a range of 200 to 400 degrees. In the second stage, the temperature of the nitrogen atmosphere is maintained within a range of 300 to 700 degrees. This causes the conductive paste to be fired. In addition, the heating in the second stage causes the bonds of some of the chemical components in the synthetic resin contained in the conductive paste to break down, resulting in the generation of voids PA.

[0048] Furthermore, during the firing of the conductive paste, copper particles 63 and silicone resin 64 are formed as follows. First, sintering of the copper component contained in the first base electrode 61A and the second base electrode 62A begins. At the time when sintering of the copper component begins, the silicon component is not hardened and has fluidity. Therefore, the silicon component fills the gaps between the copper components. Furthermore, during sintering of the copper component, sintering of the copper component begins from the surface side of the conductive paste. At this time, small copper particles 63 are coalesced into larger copper particles 63 by Ostwald ripening. As a result, the average particle size of the copper particles 63 in the second portion P2 becomes larger than the average particle size of the copper particles 63 in the first portion P1.

[0049] After the sintering of the copper component begins, when the temperature further rises to the hardening initiation temperature of the silicon component, hardening of the silicon component contained in the first base electrode 61A and the second base electrode 62A begins. That is, the hardening initiation temperature of the silicon component is higher than the sintering initiation temperature of the copper component. Then, copper particles 63 are generated by sintering the copper component. Furthermore, silicone resin 64 is generated by hardening the silicon component. Furthermore, as described above, since the hardening initiation temperature of the silicon component is higher than the sintering initiation temperature of the copper component, a network-like silicone resin 64 fills the gaps between the copper particles 63. As a result, the first base electrode 61A and the second base electrode 62A described above are formed.

[0050] Next, a plating step S15 is performed. Electroplating is performed on the first and second base electrodes 61A and 62A. As a result, a first metal layer 61C is formed on the surface of the first base electrode 61A. A second metal layer 62C is formed on the surface of the second base electrode 62A. In the plating step S15, a portion of the chemical components of the first metal layer 61C mixes with the chemical components melted from the first base electrode 61A, forming a first mixed layer 61B. The same applies to the second mixed layer 62B. Although not shown, the first and second metal layers 61C and 62C are electroplated with nickel and tin, forming a two-layer structure. In this manner, the electronic component 10 is formed.

[0051] <Effects of this embodiment> The effects of this embodiment will be described below. Note that, although the effects relating to the first external electrode 61 will be described as a representative example, the second external electrode 62 also provides similar effects.

[0052] (1) In the above embodiment, the first external electrode 61 does not contain silver. Therefore, according to the above embodiment, migration can be suppressed more effectively than when the first external electrode 61 contains silver.

[0053] Furthermore, in the above embodiment, the average particle size of the copper particles 63 in the second portion P2 is larger than the average particle size of the copper particles 63 in the first portion P1. Due to the larger particle size of the copper particles 63 in the second portion P2, the number of copper particles 63 contained in the second portion P2 is smaller than that in the first portion P1. Therefore, the contact area between each copper particle 63 and other copper particles 63 in the second portion P2 is smaller than that in the first portion P1. As a result, the mechanical strength of the second portion P2 is lower than that of the first portion P1. Therefore, if an impact is applied to the electronic component 10, cracks are more likely to occur in the second portion P2 than in the first portion P1. In other words, the second portion P2 plays a role in mitigating the effects of the impact by breaking itself. Therefore, when an impact is applied to the electronic component 10, the second portion P2 absorbs the impact, making it less likely that cracks will occur in the element body 20. Furthermore, the second portion P2 of the first base electrode 61A, which is farther from the element body 20, can exhibit the above-described impact absorbing effect, making it less likely that an impact will affect the element body 20. That is, according to the above embodiment, it is possible to suppress the occurrence of migration while suppressing the impact on the element body 20.

[0054] (2) In the above embodiment, the ratio of the average particle size of the copper particles 63 in the second portion P2 to the average particle size of the copper particles 63 in the first portion P1 is 1.2 or more. This configuration makes it easier for the second portion P2 to exhibit the impact absorbing effect.

[0055] (3) In the above embodiment, the average particle size of the copper particles 63 in the second portion P2 is 100 nm or more. With this configuration, the average particle size of the copper particles 63 in the second portion P2 is appropriately large, which reduces the contact area between the copper particles 63. In other words, by intentionally reducing the mechanical strength of the second portion P2, the impact absorbing effect on the element body 20 can be further improved.

[0056] (4) In the above embodiment, the average particle size of the copper particles 63 in the first portion P1 is 75 nm or less. In this configuration, the average particle size of the copper particles 63 in the first portion P1 is appropriately small, which increases the contact area between the copper particles 63. In other words, with the above configuration, the mechanical strength of the first portion P1 is ensured, thereby preventing cracks occurring in the second portion P2 from propagating throughout the entire first base electrode 61A, including the first portion P1.

[0057] (5) In the above embodiment, the acute angle Q between the major axis V1 of the elliptical copper particle 63 in the specific cross section and the axis L along the outer surface BD61A of the first base electrode 61A is 45 degrees or less. In other words, the copper particles 63 are oriented such that they are elongated horizontally in a direction along the outer surface BD61A of the first base electrode 61A. Cracks are likely to occur in the gaps between the copper particles 63. Therefore, if a crack occurs in the second portion P2, the crack is likely to extend in a direction along the outer surface BD61A of the first base electrode 61A. Therefore, with the above configuration, even if a crack occurs in the second portion P2, the crack is unlikely to propagate to the first portion P1.

[0058] (6) In the above embodiment, the proportion of the voids PA in the second portion P2 is greater than the proportion of the voids PA in the first portion P1. If an impact is applied to the first base electrode 61A, cracks are likely to occur starting from the voids PA. Therefore, with the above configuration, cracks are more likely to occur in the second portion P2 than in the first portion P1. As a result, the impact absorbing effect of the second portion P2 can be reliably obtained.

[0059] (7) In the above embodiment, the first mixed layer 61B contains a chemical component that is not contained in the first base electrode 61A but is contained in the first metal layer 61C. The first mixed layer 61B also contains a chemical component that is not contained in the first metal layer 61C but is contained in the first base electrode 61A. In other words, the first mixed layer 61B is a mixture of the chemical components of the first base electrode 61A and the first metal layer 61C near the boundary between them. This configuration results in a structure in which the first base electrode 61A is partially integrated with the first metal layer 61C, making the first metal layer 61C less likely to peel off from the first base electrode 61A.

[0060] <Modifications> The above embodiment and the following modifications can be implemented in combination with each other to the extent that no technical contradiction occurs. In the case of a modification that can be commonly applied to the first external electrode 61 and the second external electrode 62, the modification related to the first external electrode 61 will be described as a representative example.

[0061] In the above embodiment, 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, etc. In the above embodiment, the material of the element body 20 may be a dielectric, a piezoelectric material, a magnetic material such as ferrite, a composite of synthetic resin and metal, etc.

[0062] The shape of the element body 20 is not limited to the example in the above embodiment. For example, the element body 20 may be a polygonal columnar shape other than a quadrangular columnar shape having a central axis CA. The element body 20 may also be the core of a wire-wound inductor component. For example, the core may have a so-called drum core shape. Specifically, the core may have a columnar winding core portion and flange portions provided at each end of the winding core portion.

[0063] The boundary portion between adjacent flat surfaces on the outer surface 21 of the element body 20 does not have to be chamfered. In this case, there is no curved surface at the boundary portion. The shapes of the first internal electrodes 41 and second internal electrodes 42 are not important as long as they ensure electrical conduction with the corresponding first external electrodes 61 and second external electrodes 62. Furthermore, the number of first internal electrodes 41 and second internal electrodes 42 is not important and may be more or less than four.

[0064] In the above embodiment, the first external electrode 61 does not need to have the first mixed layer 61B. That is, the boundary between the first base electrode 61A and the first metal layer 61C may be clearly defined. In a configuration without the first mixed layer 61B, the first metal layer 61C only needs to cover at least a portion of the first base electrode 61A.

[0065] In the above embodiment, the average value of the thickness H of the first base electrode 61A is not limited to the example of the above embodiment. The overall thickness of the first external electrode 61, including the first base electrode 61A, may be designed taking into consideration the mechanical strength required of the electronic component 10, etc.

[0066] In the above embodiment, the configuration related to the first metal layer 61C in the first external electrode 61 may be omitted. Furthermore, the material of the first metal layer 61C is not limited to the example in the above embodiment. For example, the first metal layer 61C may be made of only nickel, only tin, or may contain a material other than silver. For example, the first metal layer 61C may be made of copper, gold, palladium, or the like.

[0067] In the above embodiment, the synthetic resin is not limited to the silicone resin 64. For example, the synthetic resin may be a synthetic resin containing silicon, such as a silicone oligomer. When the synthetic resin contains silicon, the first base electrode 61A is likely to become a dense film. Furthermore, the synthetic resin contained in the first base electrode 61A may contain nitrogen. For example, the synthetic resin may be a nitrogen-containing synthetic resin such as urethane, epoxy, polyimide, polyimideamide, or polyamide. When the synthetic resin contains nitrogen, the heat resistance of the first base electrode 61A is improved.

[0068] The synthetic resin is not limited to resins containing nitrogen and silicon, and may be acrylic, alkyd, polyester, or other synthetic resins. The first base electrode 61A may be a composite of these nitrogen-containing synthetic resins, silicon-containing synthetic resins, and other synthetic resins. The first base electrode 61A may be a synthetic resin containing silicon and nitrogen in a single type of synthetic resin.

[0069] In the above embodiment, the average particle size of the copper particles 63 in the first portion P1 may be greater than 75 nm. The average particle size of the copper particles 63 in the second portion P2 may be smaller than 100 nm. The ratio of the average particle size of the copper particles 63 in the second portion P2 to the average particle size of the copper particles 63 in the first portion P1 may be less than 1.2. To more effectively achieve the effect described in (2) above, the ratio of the average particle size of the copper particles 63 in the second portion P2 to the average particle size of the copper particles 63 in the first portion P1 is preferably 1.4 or greater, and more preferably 1.6 or greater.

[0070] In the above embodiment, the acute angle Q between the long axis V1 of the copper particle 63 and the axis L along the outer surface BD61A of the first base electrode 61A may be greater than 45 degrees. Note that, in the above embodiment, the flattening ratio of the copper particle 63 may be greater than 0.5. Furthermore, in the specific cross section, all of the copper particles 63 may be substantially circular.

[0071] In the above embodiment, the proportion of the void PA in the second portion P2 may be the same as or smaller than the proportion of the void PA in the first portion P1. Also, in the above embodiment, the first base electrode 61A does not have to have the void PA.

[0072] The manufacturing process of the electronic component 10 in the above embodiment is not limited to the example of the above embodiment. For example, the element body 20 may be subjected to a process such as physical polishing. In the above embodiment, the method for applying the conductive paste is not limited to the example of the above embodiment. For example, the paste may be applied by printing, or may be applied by an inkjet method or the like.

[0073] In the curing step S14 of the above embodiment, the heating may be performed three or more times, or may be performed only once. In the above embodiment, the sintering start temperature of the copper component of the conductive paste and the curing start temperature of the silicon component are not limited to the examples in the above embodiment.

[0074] In the plating step S15 of the above embodiment, the first metal layer 61C may be formed by other methods, such as sputtering. In the above embodiment, the conductive paste may be nanoink. If it is nanoink, it is prepared as follows: Nanometal powder is dispersed in a solvent containing cellosolves, carbitols, hydrocarbons, aromatics, or the like. Then, various silicone-modified resins, silicone resins, sol-gel materials, or the like are added in an amount of 0.001-10 wt % relative to the weight of Cu alone. The nanoink conductive paste may be prepared in this manner, or a different method may be used.

[0075] In the above embodiment, the material used when the conductive paste is a complex ink is not limited to the example of the above embodiment. For example, the amine compound may be a primary amine, secondary amine, or tertiary amine, and the number of N atoms is not limited. For example, it may be a primary amine such as octylamine or hexylamine, a secondary amine such as di-n-butylamine, or a tertiary amine such as N,N-dimethylhexylamine. The amine compound may also be an alcohol amine or a diamine, and the positional relationship between the N atom and the OH group is not limited to the α, β, or γ position. Furthermore, the number of N and O atoms in one molecule is not particularly limited. For example, it may be an α-hydroxyamine such as 2-dimethylaminoethanol or 2-ethylaminoethanol, or a β-hydroxyamine such as 3-amino-1-propanol or 4-amino-2-butanol. Furthermore, it may be a diamine such as ethylenediamine, or a cyclic diamine such as piperazine. The silicon component may be, for example, various silicone-modified resins such as epoxy resins, polyester resins, and phenolic resins, or sol-gel materials. Furthermore, metal salts made of formic acid, acetic acid, oxalic acid, other organic acids, etc., may also be used as the metal salts. An example of this type of metal salt is anhydrous copper formate.

[0076] In the above embodiment, 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.

[0077] <Supplementary Notes> The technical concepts that can be derived from the above-described embodiments and modified examples are described below. [1] An electronic component comprising an element body and an external electrode that covers a portion of the outer surface of the element body and does not contain a silver component, wherein the external electrode has a base electrode that covers the outer surface of the element body, the base electrode containing copper particles and a synthetic resin, and when the base electrode is divided into two equal parts, a first part located on the element body side and a second part located on the opposite side from the element body, the average particle size of the copper particles in the second part is larger than the average particle size of the copper particles in the first part.

[0078] [2] The electronic component according to [1], wherein the ratio of the average particle size of the copper particles in the second portion to the average particle size of the copper particles in the first portion is 1.2 or more. [3] The electronic component according to [1] or [2], wherein the average particle size of the copper particles in the second portion is 100 nm or more.

[0079] [4] The electronic component according to any one of [1] to [3], wherein the average diameter of the copper particles in the first portion is 75 nm or less. [5] The electronic component according to any one of [1] to [4], wherein in a specific cross section perpendicular to the outer surface of the base electrode, at least some of the copper particles have an elliptical shape, and the acute angle between the major axis of the copper particle and an axis along the outer surface of the base electrode is 45 degrees or less.

[0080] [6] An electronic component described in any one of [1] to [5], wherein the base electrode has voids between the copper particles where the synthetic resin is not present, and the proportion of the voids in the second portion is greater than the proportion of the voids in the first portion.

[0081] [7] The electronic component according to any one of [1] to [6], wherein the external electrode further has a metal layer covering the outer surface of the base electrode, and a mixed layer located between the metal layer and the base electrode, and the mixed layer contains a chemical component that is not contained in the base electrode and is contained in the metal layer, and contains a chemical component that is not contained in the metal layer and is contained in the base electrode.

[0082] BD61A...outer surface P1...first portion P2...second portion PA...gap 10...electronic component 20...element body 21...outer surface 61...first external electrode 61A...first base electrode 61B...first mixed layer 61C...first metal layer 63...copper particles 64...silicone resin

Claims

1. The body and an external electrode that covers a portion of an outer surface of the element body and does not contain a silver component; Equipped with the external electrode has a base electrode covering an outer surface of the element body, The base electrode contains copper particles and a synthetic resin, When the base electrode is divided into a first portion located on the element body side and a second portion located on the opposite side to the element body, the average diameter of the copper particles in the second portion is larger than the average diameter of the copper particles in the first portion. Electronic components.

2. A ratio of the average particle size of the copper particles in the second portion to the average particle size of the copper particles in the first portion is 1.2 or more. The electronic component according to claim 1 .

3. The average particle diameter of the copper particles in the second portion is 100 nm or more. The electronic component according to claim 1 .

4. The average particle size of the copper particles in the first portion is 75 nm or less. The electronic component according to claim 1 .

5. In a specific cross section perpendicular to the outer surface of the base electrode, At least a portion of the copper particles are elliptical in shape, The acute angle between the major axis of the copper particle and the axis along the outer surface of the base electrode is 45 degrees or less. The electronic component according to claim 1 .

6. the base electrode has gaps between the copper particles in which the synthetic resin is not present, The proportion of the voids in the second portion is greater than the proportion of the voids in the first portion. The electronic component according to claim 1 .

7. the external electrode further includes a metal layer covering an outer surface of the base electrode, and a mixed layer located between the metal layer and the base electrode, The mixed layer contains a chemical component that is not contained in the base electrode and is contained in the metal layer, and contains a chemical component that is not contained in the metal layer and is contained in the base electrode. The electronic component according to claim 1 .