Electronic component, and method for manufacturing electronic component

Abstract

This electronic component comprises: an element body (20); and a first external electrode (61) that covers an outer surface (21) of the element body (20). The first external electrode (61) has a first base electrode (61A), and a first metal layer (61B) that covers the outer surface (610) of the first base electrode (61A). The first base electrode (61A) contains copper and silicon. At least a portion of the copper is in the form of copper particles (63) having a flatness ratio of at most 0.5. When the first base electrode (61A) is viewed in cross-section, a silicone resin (64), which contains silicon, is distributed to be filled between a plurality of copper particles (63).

Description

Electronic component and method for manufacturing electronic component

[0001] The present invention relates to an electronic component and a method for manufacturing an electronic component.

[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 have a base electrode and a metal layer. The base electrode covers a portion of the outer surface of the element body. The metal layer covers the outer surface of the base electrode.

[0003] Patent No. 5206440

[0004] In the electronic component described in Patent Document 1, when forming a metal layer, a plating solution is applied to the outer surface of the base electrode. At this time, the plating solution may penetrate into the base electrode. If the plating solution penetrates into the base electrode, it may cause peeling of the base electrode and the metal layer, which is undesirable.

[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, wherein the external electrode has a base electrode and a metal layer covering the outer surface of the base electrode, the base electrode containing copper and silicon, at least a portion of the copper being copper particles having an aspect ratio of 0.5 or less, and when the base electrode is viewed in cross section, the silicon is distributed so as to fill the spaces between the copper particles.

[0006] According to the above configuration, silicon is tightly distributed around the copper particles in the base electrode. That is, the base electrode is a dense film. Therefore, according to the above configuration, for example, the penetration of a plating solution for forming a metal layer into the base electrode can be suppressed.

[0007] In addition, in order to solve the above-mentioned problems, the present invention provides a method for manufacturing an electronic component, comprising: a laminate preparation step of preparing an element body; a conductor application step of applying a conductor paste containing a copper component and a silicon component to the outer surface of the element body; a curing step of heating the element body with the conductor paste applied to turn the conductor paste into a base electrode; and a plating step of immersing the element body with the base electrode formed thereon in a plating solution to form a metal layer on the outer surface of the base electrode, wherein the curing start temperature of the silicon component is higher than the sintering start temperature of the copper component, and the difference between the curing start temperature of the silicon component and the sintering start temperature of the copper component is 100 degrees or less.

[0008] According to the above configuration, sintering of the copper component in the conductive paste begins before hardening of the silicon component. Due to this difference in starting temperature, the silicon component fills the gaps between the copper particle components. Therefore, in the sintered electronic component, silicon is tightly distributed around the copper particles in the base electrode. In other words, the base electrode is a dense, dense film. Therefore, according to the above configuration, it is possible to prevent, for example, a plating solution used to form a metal layer from penetrating into the base electrode.

[0009] The metal layer is prevented from penetrating into the underlying electrode.

[0010] 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 an enlarged view of a cross-section of a first base electrode of the electronic component. FIG. 5 is an enlarged view of a cross-section of a first base electrode of the electronic component. FIG. 6 is a schematic diagram showing an enlarged view of the outer surface of a first base electrode of an electronic component. FIG. 7 is a graph showing the relationship between the weight loss rate and temperature when a test object is fired. FIG. 8 is a flowchart illustrating a method for manufacturing an electronic component.

[0011] 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.

[0012] <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.

[0013] 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.

[0014] The outer surface 21 of the element body 20 has 12 boundary surfaces 23. The boundary surfaces 23 include curved surfaces that exist at the boundaries between adjacent flat surfaces 22. That is, the boundary surfaces 23 include curved surfaces that are formed by, for example, R-chamfering the corners that form the adjacent flat surfaces 22.

[0015] The outer surface 21 of the element body 20 also has eight spherical corner surfaces 24. The corner surfaces 24 are boundary portions between three adjacent flat surfaces 22. In other words, the corner surfaces 24 include curved surfaces at the intersections of the three boundary surfaces 23. That is, the corner surfaces 24 include curved surfaces formed by, for example, R-chamfering the corners formed by the three adjacent flat surfaces 22.

[0016] As shown in Fig. 2, the element body 20 has a dimension along the first axis X that is larger than the dimension 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, a rare earth compound, or the like.

[0017] 3 , the electronic component 10 includes, as wiring, 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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, and the second internal electrodes 42 are located closer to the first negative direction X2.

[0023] Specifically, 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. 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. 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.

[0024] 3 , the electronic component 10 includes a first external electrode 61 and a second external electrode 62. The first external electrode 61 includes a first base electrode 61A and a first metal layer 61B. 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.

[0025] The first base electrode 61A is a five-sided electrode that 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. In this embodiment, the first base electrode 61A is made of copper and glass. The first base electrode 61A is a sintered body.

[0026] As shown in Fig. 3, the first metal layer 61B covers the first base electrode 61A from the outside. Therefore, the first metal layer 61B is laminated on the first base electrode 61A. Furthermore, a portion of the first metal layer 61B protrudes from the first base electrode 61A. Although not shown, the first metal layer 61B has a two-layer structure consisting of, in order from the first base electrode 61A side, a nickel layer and a tin layer. Note that the first metal layer 61B does not penetrate into the first base electrode 61A.

[0027] The second external electrode 62 has a second base electrode 62A and a second metal layer 62B. The second base electrode 62A is laminated on a portion of the outer surface 21 of the element body 20 that includes the second end face 22B.

[0028] The second base electrode 62A is a five-sided electrode that covers the second end face 22B and parts of the four side faces 22C of the element body 20 facing in 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. Similarly to the first base electrode 61A, the second base electrode 62A is a sintered body.

[0029] The second metal layer 62B covers the second base electrode 62A from the outside. Therefore, the second metal layer 62B is laminated on the second base electrode 62A. Furthermore, a portion of the second metal layer 62B protrudes from the second base electrode 62A. Although not shown, the second metal layer 62B has a two-layer structure, similar to the first metal layer 61B, consisting of a nickel layer and a tin layer, in that order from the second base electrode 62A side. Note that the second metal layer 62B does not penetrate into the second base electrode 62A.

[0030] 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.

[0031] <Configuration of First Base Electrode and Second Base Electrode> The first base electrode 61A contains copper and silicon. The first base electrode 61A is a sintered body. Note that, although the following description focuses on the first base electrode 61A, the same applies to the second base electrode 62A.

[0032] The weight ratio of copper to silicon in the first base electrode 61A is not less than 0.5 and not more than 2. As shown in Fig. 4, at least a portion of the copper in the first base electrode 61A is copper particles 63. Furthermore, the silicon in the first base electrode 61A exists as silicone resin 64. Note that the silicone resin 64 is a polymer formed of a siloxane bond and a Si-C bond.

[0033] The flattening ratio F of the copper particles 63 is 0.5 or less. Therefore, the copper particles 63 have a generally spherical appearance. The flattening ratio F is calculated as follows. First, as shown in FIG. 6 , the outline of the copper particles 63 is acquired by image processing using a scanning transmission electron microscope (STEM). The image is acquired using a scanning transmission electron microscope adjusted to a magnification of, for example, 200,000 times or more. The imaging parameters were an acceleration voltage of 200 kV and a focusing lens aperture of #3. Platinum sputter coating was performed as a pre-processing step for imaging. The image acquired under these conditions was analyzed, and half the length of the longest line segment connecting the edges of one copper particle 63 was defined as the major axis a. Furthermore, half the length of the line segment connecting the edges of the copper particles 63 that is perpendicular to the major axis a was defined as the minor axis b. In this case, the flattening ratio F was calculated based on the following formula: (Equation 1) F = 1 - (b / a) Then, using Equation 1, the flatness F of the five particles is calculated in the same manner, and the average of the flatness F of the five particles is taken as the flatness F of the entire copper particle 63.

[0034] 4, the first base electrode 61A is bisected into a first portion 631 on the inner surface 620 side of the first base electrode 61A and a second portion 632 on the outer surface 610 side of the first base electrode 61A. The inner surface 620 is the boundary surface of the first base electrode 61A that is closer to the element body 20. The outer surface 610 is the outer surface of the first base electrode 61A that is opposite to the element body 20. The position at which the first base electrode 61A is bisected is the point at which the average value of the thickness H of the first base electrode 61A, which will be described later, is divided into two equal parts.

[0035] 4 , the average particle size of copper particles 63 differs between first portion 631 and second portion 632. Specifically, the average particle size of copper particles 63 in first portion 631 is smaller than the average particle size of copper particles 63 in second portion 632. That is, the particle size of copper particles 63 located in first portion 631 is generally smaller than the particle size of copper particles 63 located in second portion 632. Overall, the particle size of copper particles 63 becomes smaller toward inner surface 620 within first base electrode 61A.

[0036] The particle diameter of copper particles 63 is twice the average of the major axis a and the minor axis b. The average particle diameter of copper particles 63 in first portion 631 is the average particle diameter of five copper particles 63 located in first portion 631. The average particle diameter of copper particles 63 in second portion 632 is the average particle diameter of five copper particles 63 located in second portion 632.

[0037] As shown in Fig. 5, the silicone resin 64 as silicon is distributed in a mesh-like pattern. Specifically, when the first base electrode 61A is viewed in cross section, the silicone resin 64 is distributed so as to fill the spaces between the multiple copper particles 63. In this embodiment, the silicone resin 64 is distributed in a mesh-like pattern, reflecting the fact that the multiple copper particles 63 are generally in point contact with each other. Furthermore, a portion of the silicone resin 64 is in a clumped state. The clumped silicone resin 64 is formed by condensing a portion of the mesh-like silicone resin 64. In particular, the first portion 631 has a higher proportion of clumped silicone resin 64 than the second portion 632.

[0038] The proportion of silicone resin 64 in the first portion 631 of the first base electrode 61A is higher than the proportion of silicone resin 64 in the second portion 632 of the first base electrode 61A. The proportion of silicone resin 64 is calculated as follows. First, a cross section of the first base electrode 61A is photographed using a scanning electron microscope (SEM-EDX). The image is acquired using a scanning electron microscope adjusted to a magnification of, for example, 200,000 times or more. The photographing parameters are a spot diameter of 5, a time constant of Rate 1, and an accumulation count of 100. Next, the area occupied by silicone resin 64 within a certain square range of the photographed image is calculated. The area of ​​silicone resin 64 relative to the area of ​​the square is then defined as the proportion of silicone resin 64. At this time, a square range is defined so as not to extend beyond the first portion 631, and the proportion of silicone resin 64 is calculated. Then, the proportion of the silicone resin 64 is calculated at three or more points within the range of the first portion 631, and the average value of these is set as the proportion of the silicone resin 64 in the first portion 631. The same applies to the second portion 632.

[0039] When the thickness H is the shortest distance from the inner surface 620 to the outer surface 610 of the first base electrode 61A, the average value of the thickness H of the first base electrode 61A is 700 nm. The thickness H of the first base electrode 61A is calculated as follows: First, a cross section of the first base electrode 61A, including the outer surface 610 and the inner surface 620, is photographed using a scanning transmission electron microscope. The photographing parameters are the same as the photographing conditions using the scanning transmission electron microscope described above. Next, a range in the photographed image is identified in the direction along the outer surface 610 of the first base electrode 61A. 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 thickness H of the first base electrode 61A is then calculated by dividing the cross-sectional area of ​​the first base electrode 61A within the calculated measurement range by the length of the measurement range. In other words, the thickness H of the first base electrode 61A is the thickness within the measurement range.

[0040] As shown in Fig. 5, 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 the gaps PA in the first base electrode 61A is less than 5%. In this way, if the proportion of the gaps PA in the first base electrode 61A is less than 5%, it can be said that the silicone resin 64 is distributed so as to fill the spaces between the copper particles 63. Note that the gaps PA are shown schematically in Fig. 5.

[0041] The proportion of voids PA in the first base electrode 61A is determined by the porosity measured as follows. First, the first base electrode 61A is observed in a square area with sides of 500 nm using a scanning 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 ratio of the total area of ​​the voids PA to the area of ​​the observed area. This process is repeated at four locations on the first base electrode 61A, and the average value of the porosity in each area is used as the proportion of voids PA in the first base electrode 61A.

[0042] <Method for Manufacturing Electronic Component> Next, a description will be given of a method for manufacturing electronic component 10. As shown in Fig. 8 , the method for manufacturing electronic component 10 further includes a laminate preparation step S11, an R-chamfering step S12, a conductor application step S13, a curing step S14, and a plating step S15.

[0043] First, in forming the element body 20, in the laminate preparation step S11, a laminate is prepared, which is the element body 20 without boundary surfaces 23 and corner surfaces 24. That is, the laminate is in a state before R-chamfering and has a rectangular parallelepiped shape with six flat surfaces 22. For example, first, multiple ceramic sheets that will become the element body 20 are prepared. The sheets are thin plate-like. 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 laminating 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. The laminated sheets are then pressed in the stacking direction using a mold press or other means. The pressed 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 S12 is performed. In the R-chamfering process S12, a boundary surface 23 and a corner surface 24 are formed on the laminate prepared in the laminate preparation process S11. For example, the corners of the laminate are R-chamfered by barrel polishing, thereby forming the curved boundary surface 23 and the curved corner surface 24.

[0045] Next, a conductor application step S13 is performed. In the conductor application step S13, a 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.

[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 10-300 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. The methods for determining the sintering start temperature of the copper component and the hardening start temperature of the silicon component will be described later.

[0047] Next, a curing step S14 is performed. Specifically, in the curing step S14, the element body 20 coated with the conductive paste is heated. In this embodiment, the element body 20 coated with the conductive paste is heated in a nitrogen atmosphere. The temperature is maintained at a range of 300 to 600 degrees Celsius. This causes the conductive paste to be fired. During the firing of the conductive paste, sintering of the copper component contained in the first base electrode 61A and the second base electrode 62A begins first. When sintering of the copper component begins, the silicon component is not hardened and remains fluid. Therefore, the silicon component fills the gaps between the copper components. After 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. In other words, the hardening initiation temperature of the silicon component is higher than the sintering initiation temperature of the copper component. The sintering of the copper component generates copper particles 63. Furthermore, silicone resin 64 is produced by hardening the silicon component. As described above, the hardening start temperature of the silicon component is higher than the sintering start temperature of the copper component, resulting in a network of silicone resin 64 that fills the gaps between the copper particles 63. As a result, the first base electrode 61A and the second base electrode 62A are formed as described above. As described above, the hardening start temperature of the silicon component is higher than the sintering start temperature of the copper component, resulting in the silicone resin 64 becoming a dense film that fills the gaps between the copper particles 63. As a result, the proportion of voids PA in the first base electrode 61A and the second base electrode 62A is reduced. By setting the hardening start temperature of the silicon component and the sintering start temperature of the copper component to have such a magnitude relationship, the proportion of voids PA can be reduced.

[0048] Next, a plating step S15 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. Although not shown, 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.

[0049] <Regarding the sintering start temperature of the copper component and the hardening start temperature of the silicon component> The sintering start temperature of the copper component was measured as follows. First, a complex ink composed of the copper component was prepared. Then, a thermal analyzer (Thermo Plus EVO2 manufactured by Rigaku) ​​was used to measure the weight change of the complex ink during firing.

[0050] The weight loss rate is defined as 100% as the ratio of the weight of the complex ink before sintering to the weight of the ink when the temperature is raised to 600°C. The temperature at which the weight loss rate after the start of sintering is 99% is defined as the sintering start temperature. For example, if the weight loss from before sintering is 10 mg when the temperature is raised to 600°C, the temperature at which the weight loss is 9.9 mg, i.e., the weight loss rate is 99%, is defined as the sintering start temperature.

[0051] Specifically, the sintering start temperature of the copper component was measured under the following conditions using a complex ink as the test subject. The temperature at the start of the test was 40°C. The temperature increase rate was 10°C / min. The temperature at the end of the test was 600°C. As shown in FIG. 7 , when the weight loss at 600°C is normalized as 100%, 99% of the weight loss occurs at a temperature of 170°C. In other words, the sintering start temperature of the copper component is 170°C.

[0052] The curing temperature of the silicon component was measured as follows. In the measurement test, the test object was a stretched silicon paste. Then, in the measurement test, the test object was fired. At this time, the maximum value of the firing temperature was changed in increments of 10 degrees. The test object after firing was touched with a finger, and the temperature at which it felt that the tackiness had disappeared was taken as the curing initiation temperature. Tackiness was evaluated in accordance with JIS K 5600-1-1 4.3.5 (c. A state in which no scratches are left on the coated surface in the evaluation based on JIS is considered to be a state in this embodiment in which there is no tackiness. Specifically, the test object in this test was a slide glass on which silicone resin was squeegeeed to a thickness of 500 μm. In the test, first, the test object was placed on a hot plate and heated at 150° C. for 10 minutes. Thereafter, the test object was evaluated in accordance with JIS. Thereafter, the heating temperature was increased by 10° C. and the test object was heated for 10 minutes, and then the evaluation based on JIS was again performed. In this way, the evaluation based on JIS was performed every time the heating temperature of the test piece was increased by 10° C., and the temperature at which it was felt that tackiness had disappeared was taken as the hardening start temperature of the silicon component. The measurement was performed in the atmosphere. In this embodiment, the hardening start temperature of silicon in this test was 250° C.

[0053] <Regarding Observation and Inspection> The following electronic components of Examples 1 to 12 and Comparative Examples 1 to 4 were fabricated. The first base electrodes of the electronic components of these Examples and Comparative Examples were observed. Note that the electronic components of Examples 1 to 12 and the electronic components of Comparative Examples 1 to 4 have the same configurations of the element body, each internal electrode, first metal layer, etc.

[0054] <Regarding Examples 1 to 12 and Comparative Examples 1 to 4> Electronic components of Examples 1 to 12 and Comparative Examples 1 to 4 will be described below. In the electronic component of Example 1, the void ratio in the first base electrode is 1%. In the electronic component of Example 1, the average thickness H of the first base electrode is 550 nm. In the electronic component of Example 1, the flatness of the copper particles is 0.2.

[0055] In the electronic component of Example 2, the proportion of voids in the first base electrode is 1%. In the electronic component of Example 2, the average value of the thickness H of the first base electrode is 550 nm. In the electronic component of Example 2, the flatness of the copper particles is 0.4.

[0056] In the electronic component of Example 3, the proportion of voids in the first base electrode is 3%. In the electronic component of Example 3, the average value of the thickness H of the first base electrode is 500 nm. In the electronic component of Example 3, the flatness of the copper particles is 0.5.

[0057] In the electronic component of Example 4, the void ratio in the first base electrode is 1%. In the electronic component of Example 4, the average value of the thickness H of the first base electrode is 750 nm. In the electronic component of Example 4, the flatness of the copper particles is 0.2.

[0058] In the electronic component of Example 5, the proportion of voids in the first base electrode is 3%. In the electronic component of Example 5, the average value of the thickness H of the first base electrode is 800 nm. In the electronic component of Example 5, the flatness of the copper particles is 0.4.

[0059] In the electronic component of Example 6, the proportion of voids in the first base electrode is 3%. In the electronic component of Example 6, the average value of the thickness H of the first base electrode is 750 nm. In the electronic component of Example 6, the flatness of the copper particles is 0.5.

[0060] In the electronic component of Example 7, the proportion of voids in the first base electrode is 2%. In the electronic component of Example 7, the average value of the thickness H of the first base electrode is 1200 nm. In the electronic component of Example 7, the flatness of the copper particles is 0.2.

[0061] In the electronic component of Example 8, the proportion of voids in the first base electrode is 3%. In the electronic component of Example 8, the average value of the thickness H of the first base electrode is 1100 nm. In the electronic component of Example 8, the flatness of the copper particles is 0.4.

[0062] In the electronic component of Example 9, the proportion of voids in the first base electrode is 4%. In the electronic component of Example 9, the average value of the thickness H of the first base electrode is 1300 nm. In the electronic component of Example 9, the flatness of the copper particles is 0.5.

[0063] In the electronic component of Example 10, the proportion of voids in the first base electrode is 3%. In the electronic component of Example 10, the average value of the thickness H of the first base electrode is 1800 nm. In the electronic component of Example 10, the flatness of the copper particles is 0.2.

[0064] In the electronic component of Example 11, the void ratio in the first base electrode is 4%. In the electronic component of Example 11, the average value of the thickness H of the first base electrode is 1950 nm. In the electronic component of Example 11, the flatness of the copper particles is 0.4.

[0065] In the electronic component of Example 12, the void ratio in the first base electrode is 4%, the average thickness H of the first base electrode is 2000 nm, and the flatness of the copper particles is 0.5.

[0066] In the electronic component of Comparative Example 1, the proportion of voids in the first base electrode is 3%. In the electronic component of Comparative Example 1, the average value of the thickness H of the first base electrode is 350 nm. In the electronic component of Comparative Example 1, the flatness of the copper particles is 0.2.

[0067] In the electronic component of Comparative Example 2, the proportion of voids in the first base electrode is 5%. In the electronic component of Comparative Example 2, the average value of the thickness H of the first base electrode is 750 nm. In the electronic component of Comparative Example 2, the flatness of the copper particles is 0.6.

[0068] In the electronic component of Comparative Example 3, the proportion of voids in the first base electrode is 8%. In the electronic component of Comparative Example 3, the average value of the thickness H of the first base electrode is 750 nm. In the electronic component of Comparative Example 3, the flatness of the copper particles is 0.7.

[0069] In the electronic component of Comparative Example 4, the proportion of voids in the first base electrode is 4%. In the electronic component of Comparative Example 4, the average value of the thickness H of the first base electrode is 2200 nm. In the electronic component of Comparative Example 4, the flatness of the copper particles is 0.3.

[0070] <Results of Observation Inspection> The results of the observation inspection of the electronic components of Examples 1 to 12 and Comparative Examples 1 to 4 will be described below.

[0071] An external observation inspection was performed on the first base electrode. In the inspection, first, the first base electrode was observed from the first end face side of the element body using an optical microscope. Then, the presence or absence of cracks and film breaks in the first base electrode was determined. Film breaks were determined to have occurred when the first base electrode was unable to cover the entire first end face. Note that the external observation of the first base electrode was performed before the first metal layer was formed on the first base electrode.

[0072] No problems were observed in the appearance of the first base electrode in the electronic components of Examples 1 to 12 and Comparative Examples 2 and 3. That is, the first base electrodes of the electronic components of Examples 1 to 12 and Comparative Examples 2 and 3 were continuous films covering the entire first end face of the element body. Film breaks were observed in the first base electrode of the electronic component of Comparative Example 1. Furthermore, cracks were observed in the first base electrode of the electronic component of Comparative Example 4.

[0073] The observation results of Examples 1 to 12 and Comparative Example 1 showed that film breakage was observed when the average thickness of the first base electrode was less than 500 nm. In other words, it is preferable that the average thickness of the first base electrode be 500 nm or more.

[0074] Furthermore, from the observation results of Examples 1 to 12 and Comparative Example 4, it was found that cracks were observed when the average thickness of the first base electrode was greater than 2000 nm. In other words, it can be said that it is preferable that the average thickness of the first base electrode be 2000 nm or less.

[0075] An observation and inspection was conducted on the cross section of the first base electrode. Specifically, the presence or absence of intrusion of plating solution into the first base electrode was observed. First, cross-sectional images of the first base electrode were photographed using a scanning electron microscope (SEM-EDX). Images were taken at a magnification of 200,000 times or more for four different cross sections. In each cross section, if components of the first metal layer were detected at a position at least 10% of the average thickness of the first base electrode 61A from the outer surface of the first base electrode, it was determined that plating solution had intruded. In the judgment, if intrusion of plating solution was observed in even one of the four observed cross sections, it was determined that plating solution had intruded.

[0076] In the first base electrodes of Examples 1 to 12, no penetration of the plating solution was observed. In Comparative Examples 1 to 4, penetration of the plating solution was observed. That is, the observation results of Examples 1 to 12 and Comparative Example 1 showed that when the average thickness of the first base electrode was less than 500 nm, the plating solution penetrated into the first base electrode. In other words, it can be said that it is preferable for the average thickness of the first base electrode to be 500 nm or more.

[0077] Furthermore, the observation results of Examples 1 to 12 and Comparative Example 4 showed that the plating solution penetrated into the first base electrode when the average thickness of the first base electrode was greater than 2000 nm. In other words, it can be said that it is preferable for the average thickness of the first base electrode to be 2000 nm or less.

[0078] Furthermore, the observation results of Examples 1 to 12 and Comparative Examples 2 and 3 revealed that the plating solution penetrated into the first base electrode when the copper particle flatness was greater than 0.5. In other words, it is preferable that the copper particle flatness be 0.5 or less.

[0079] Furthermore, the observation results of Examples 1 to 12 and Comparative Examples 2 and 3 revealed that the plating solution penetrated into the first base electrode when the porosity of the first base electrode was 5% or more. In other words, it can be said that it is preferable for the porosity of the first base electrode to be less than 5%.

[0080] <Effects of this embodiment> The effects of this embodiment will be described below. Note that, although the effects relating to the first base electrode 61A will be described as a representative example, the second base electrode 62A also provides similar effects.

[0081] (1) In the above embodiment, the silicone resin 64 is tightly distributed around the copper particles 63. In other words, the first base electrode 61A is a dense, dense film. Therefore, with the above configuration, for example, it is possible to prevent a plating solution or the like used to form the first metal layer 61B from penetrating into the first base electrode 61A.

[0082] (2) The silicone resin 64 has a stronger adhesive force with other members than the copper particles 63. In the above embodiment, the proportion of the silicone resin 64 in the first portion 631 of the first base electrode 61A is higher than the proportion of the silicone resin 64 in the second portion 632 of the first base electrode 61A. In other words, the silicone resin 64 is likely to be exposed on the inner surface 620 of the first base electrode 61A. Therefore, the silicone resin 64 easily adheres to the element body 20, and the first base electrode 61A is less likely to peel off from the element body 20.

[0083] (3) In the above embodiment, the average thickness H of the first base electrode 61A is 700 nm. When the average thickness H of the first base electrode 61A is this value, stress generated during sintering can be reduced. Furthermore, the average thickness H of the first base electrode 61A is in the range of 500 nm or more and 2000 nm or less. Therefore, according to the results of the above observation and inspection, this configuration can suppress the occurrence of film breaks and cracks in the first base electrode 61A. Furthermore, according to this configuration, it can be said that the effect of suppressing the penetration of plating solution, etc. used to form the first metal layer 61B into the first base electrode 61A is high.

[0084] (4) In the above embodiment, the average particle size of the copper particles 63 in the first portion 631 of the first base electrode 61A is smaller than the average particle size of the copper particles 63 in the second portion 632 of the first base electrode 61A. That is, copper particles 63 with small particle sizes tend to be densely packed on the inner surface 620. This tends to ensure a reliable electrical connection between the first base electrode 61A and the first internal electrode 41.

[0085] (5) In the above embodiment, in the curing step S14, sintering of the copper component in the conductive paste begins before hardening of the silicon component. As described above, due to this difference in starting temperature, the silicon component fills the gaps between the copper particle components. By utilizing this difference in starting temperature, it is easy to realize a structure in which silicon is distributed in a network pattern in the first base electrode 61A.

[0086] (6) As described above, in the curing step S14, the silicon component is distributed in the gaps between the copper components. This suppresses the progress of sintering of the copper component. As a result, the particle size of the formed copper particles 63 is less likely to become large. In other words, according to the above embodiment, stress caused by excessive growth of the copper particles 63 during sintering can be suppressed.

[0087] (7) If the difference between the sintering start temperature of the copper component and the hardening start temperature of the silicon component is large, the copper components may bond together to form a film before the silicon component hardens. If the copper components bond together in a film-like manner, the silicon component will be less likely to be distributed in a network-like manner. If the difference between the sintering start temperature of the copper component and the hardening start temperature of the silicon component is about 80 degrees, as in the above embodiment, the copper components can be prevented from bonding together in a film-like manner as described above.

[0088] <Modifications> The above embodiment and the following modifications can be implemented in combination with each other within the scope of technical compatibility.

[0089] 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, or the like, which includes the element body 20, the first external electrode 61, and the second external electrode 62.

[0090] In the above embodiment, the material of the element 20 may be a dielectric, a piezoelectric, a magnetic material such as ferrite, or a composite of synthetic resin and metal. 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 10-300 wt % relative to the weight of Cu alone. The conductive paste of nanoink may be prepared in this manner, or a different method may be used.

[0091] 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.

[0092] In the above embodiment, 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.

[0093] 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.

[0094] In the above embodiment, the proportion of the silicone resin 64 in the first portion 631 of the first base electrode 61A may be lower than or the same as the proportion of the silicone resin 64 in the second portion 632 of the first base electrode 61A. The same applies to the second base electrode 62A.

[0095] In the above embodiment, the average value of the thickness H of the first base electrode 61A is not limited to the example in the above embodiment. Note that, in order to reduce stress generated during firing, the average value of the thickness H of the first base electrode 61A is preferably 500 nm or more and 2000 nm or less. This also applies to the second base electrode 62A.

[0096] In the above embodiment, the average particle size of the copper particles 63 in the first portion 631 of the first base electrode 61A may be equal to or smaller than the average particle size of the copper particles 63 in the second portion 632 of the first base electrode 61A. This also applies to the second base electrode 62A.

[0097] In the above embodiment, silicon is not limited to the silicone resin 64. For example, silicon may be silica (silicon dioxide) or the like. In the above embodiment, the curing step S14 may be performed multiple times. That is, baking may be performed multiple times.

[0098] In the above embodiment, the difference between the sintering start temperature of the copper component of the conductive paste and the hardening start temperature of the silicon component is not limited to the example of the above embodiment. However, in order to maintain the spherical shape of the copper component, the difference between these start temperatures is preferably 100°C or less.

[0099] In the above embodiment, the hardening initiation temperature of the silicon component may be measured by a different method. In the above embodiment, the sintering initiation temperature of the copper component may be measured by a different method. For example, first, a nanopowder pellet composed of the copper component is prepared. Then, a thermomechanical analyzer TMA (TA7000, manufactured by Hitachi High-Tech Science) is used to measure the shrinkage of the pellet during sintering. Specifically, a cylindrical pellet with a diameter of 5 mm and a height of 5 mm is used as the test subject, and the height of the pellet during sintering is measured. Then, when a two-dimensional graph of height and temperature is drawn, the temperature at which the height reaches an inflection point is determined as the sintering initiation temperature.

[0100] In the plating step S15 of the above embodiment, the first metal layer 61B may be formed by other methods, such as sputtering. The same applies to the second metal layer 62B. In the above embodiment, the material of the first metal layer 61B is not limited to the example in the above embodiment. For example, the first metal layer 61B may be made of only nickel, only tin, or may contain other materials. For example, the material of the first metal layer 61B may be copper, silver, gold, palladium, etc. The same applies to the second metal layer 62B.

[0101] In the above embodiment, the copper particles 63 may be an alloy containing a copper component. For example, the copper particles 63 may be an alloy of copper and a metal such as silver, gold, palladium, or nickel.

[0102] The technical concepts that can be derived from the above-described embodiments and modifications are described below: [1] An electronic component comprising an element body and an external electrode covering a portion of an outer surface of the element body, the external electrode having a base electrode and a metal layer covering the outer surface of the base electrode, the base electrode containing copper and silicon, at least a portion of the copper being copper particles having an aspect ratio of 0.5 or less, and the silicon being distributed so as to fill spaces between a plurality of the copper particles when the base electrode is viewed in cross section.

[0103] [2] An electronic component according to [1], wherein 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 proportion of silicon in the first part is higher than the proportion of silicon in the second part.

[0104] [3] An electronic component according to [1] or [2], wherein the average thickness of the base electrode is 500 nm or more and 2000 nm or less, when the thickness is the shortest distance from the surface of the base electrode on the side of the element body opposite the outer surface of the base electrode to the outer surface of the base electrode.

[0105] [4] An electronic component described in any one of [1] to [3], wherein 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 diameter of the copper particles in the first part is smaller than the average diameter of the copper particles in the second part.

[0106] [5] The electronic component according to any one of [1] to [4], wherein the silicon is a silicone resin. [6] A method for manufacturing an electronic component, comprising: a laminate preparation step of preparing an element body, a conductor application step of applying a conductor paste containing a copper component and a silicon component to the outer surface of the element body, a curing step of heating the element body with the conductor paste applied to turn the conductor paste into a base electrode, and a plating step of immersing the element body with the base electrode formed thereon in a plating solution to form a metal layer on the outer surface of the base electrode, wherein the curing start temperature of the silicon component is higher than the sintering start temperature of the copper component, and the difference between the curing start temperature of the silicon component and the sintering start temperature of the copper component is 100 degrees or less.

[0107] REFERENCE SIGNS LIST 10... Electronic component 20... Element body 61... First external electrode 61A... First base electrode 61B... First metal layer 62... Second external electrode 62A... Second base electrode 62B... Second metal layer 63... Copper particles 64... Silicone resin 631... First portion 632... Second portion

Claims

1. The body and an external electrode covering a part of an outer surface of the element body; Equipped with the external electrode has a base electrode and a metal layer covering an outer surface of the base electrode, the base electrode contains copper and silicon; At least a portion of the copper is in the form of copper particles having an aspect ratio of 0.5 or less, When the base electrode is viewed in cross section, the silicon is distributed so as to fill spaces between the copper particles, 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 proportion of silicon in the first portion is higher than the proportion of silicon in the second portion. Electronic components.

2. When the shortest distance from the surface of the base electrode on the side of the element body opposite to the outer surface of the base electrode to the outer surface of the base electrode is defined as a thickness, The average thickness of the base electrode is 500 nm or more and 2000 nm or less. The electronic component according to claim 1 .

3. 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 first portion is smaller than the average diameter of the copper particles in the second portion. The electronic component according to claim 1 .

4. The silicon is a silicone resin. The electronic component according to claim 1 .

5. a laminate preparation step of preparing an element body; a conductor coating step of coating an outer surface of the element body with a conductor paste containing a copper component and a silicon component; a curing step of heating the element body to which the conductive paste has been applied to convert the conductive paste into a base electrode; a plating step of immersing the body on which the base electrode is formed in a plating solution to form a metal layer on an outer surface of the base electrode; having the hardening initiation temperature of the silicon component is higher than the sintering initiation temperature of the copper component; The difference between the hardening start temperature of the silicon component and the sintering start temperature of the copper component is 100 degrees or less. A method for manufacturing electronic components.