Electronic component mounting structure

Abstract

In the mounting structure of the electronic component, an alloy containing a Ni component contained in each external electrode and the land of the substrate and a Sn component contained in the solder is generated in the manufacturing process. Since the alloy is hard and brittle, the thick growth of the alloy in the mounting structure may cause a decrease in the bonding strength of the electronic component to the land of the substrate.SOLUTION: An electronic component mounting structure 100 includes a substrate 70 having a land 72, a capacitor component 10 having a first external electrode 61 laminated on an outer surface of an element body, and solder 80 containing Sn. At least one of the first outer electrode 61 and the land 72 contains Ni. The first outer electrode 61 is joined to the land 72 by solder 80. The solder 80 contains particles 82 containing Cu, and has a portion protruding outward from an outer edge of the capacitor component 10 when viewed in a direction orthogonal to the substrate 70. The particles 82 are located between the first outer electrode 61 and the land 72 and in the protruding portion.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a mounting structure for electronic components. [Background technology]

[0002] Patent Document 1 discloses a structure in which a multilayer ceramic capacitor is mounted on a land of a substrate by soldering. The multilayer ceramic capacitor of Patent Document 1 includes a dielectric layer, a plurality of internal electrode layers, and external electrodes. Each internal electrode extends inside the dielectric layer. An end of each internal electrode is exposed from the surface of the dielectric layer. The external electrodes are laminated on the surface of the dielectric layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-111361 Summary of the Invention [Problem to be solved by the invention]

[0004] In the mounting structure of electronic components as described in Patent Document 1, an alloy containing Ni components contained in each external electrode and the land of the substrate and Sn components contained in the solder is generated during the manufacturing process. This alloy may grow thick when exposed to high heat, for example. Because this alloy is hard and brittle, the thick growth of this alloy in the mounting structure can cause a decrease in the bonding strength of the electronic component to the land of the substrate. [Means for solving the problem]

[0005] In order to solve the above problems, the present invention provides a mounting structure for an electronic component comprising a substrate having lands, an electronic component having an element body and external electrodes laminated on the outer surface of the element body, and solder containing Sn, wherein at least one of the external electrodes and the lands contains Ni, the external electrodes are joined to the lands with the solder, the solder contains particles containing Cu, and when viewed in a direction perpendicular to the substrate, has a portion that protrudes outward from the outer edge of the electronic component, and the particles are located between the external electrodes and the lands and in the protruding portion. [Effects of the Invention]

[0006] According to the present invention, it is possible to suppress a decrease in the bonding strength of the electronic component to the land of the substrate. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a partial cross-sectional perspective view of a capacitor component. [Figure 2] FIG. 2 is a partial cross-sectional view of a mounting structure for a capacitor component. [Figure 3] FIG. 3 is a schematic diagram showing the substrate preparation step. [Figure 4] FIG. 4 is a schematic diagram showing the solder application step. [Figure 5] FIG. 5 is a schematic diagram showing the mounting process. [Figure 6] FIG. 6 is a schematic diagram showing the heating step. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment in which the present invention is applied to a capacitor component 10 as an electronic component will be described below with reference to the drawings. Note that the drawings may show components enlarged to facilitate understanding. The dimensional ratios of the components may differ from those in the actual product or from those in other drawings.

[0009] <About capacitor components> As shown in FIG. 1, the capacitor component 10 is a multilayer ceramic capacitor. The capacitor component 10 includes an element body 20. Note that FIG. 1 illustrates the capacitor component 10 with a portion thereof virtually cut away to show its internal structure. The element body 20 has a rectangular parallelepiped shape and has a central axis CA. Note that, hereinafter, 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. Furthermore, 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 opposite to the first positive direction X1 is referred to as a first negative direction X2. Furthermore, 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 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 of the element body 20 is composed of six flat surfaces 22. Note that the "surface" of the element body 20 here 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, 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 facing the first negative direction X2, and four side surfaces 22C. The four side surfaces 22C are 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, respectively.

[0011] As shown in FIG. 1, the dimension of element body 20 along the first axis X is greater than the dimensions along the second axis Y and the dimensions along the third axis Z. The material of element body 20 is a dielectric ceramic. Specifically, the material of element body 20 is primarily composed of BaTiO3. However, the material of element body 20 may also be primarily composed of CaTiO3, SrTiO3, CaZrO3, etc. Furthermore, the material of element body 20 may also contain, as a secondary component, a Mn compound, a Co compound, a Si compound, or a compound containing a rare earth element, etc.

[0012] As shown in Fig. 1, the capacitor component 10 includes five 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. Note that in Fig. 1, only some of the first internal electrodes 41 and some of the second internal electrodes 42 are labeled with reference numerals.

[0013] The material of the first internal electrode 41 is a conductive material. Specifically, the material of the first internal electrode 41 is Ni. The material of the second internal electrode 42 is the same as the material of the first internal electrode 41.

[0014] The first internal electrode 41 has a rectangular plate shape. The main surface of the first internal electrode 41 is perpendicular to the third axis Z. 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 third axis Z, similar to the first internal electrode 41. Note that the main surface here refers to the flat surface with the largest area among the outer surfaces of a plate-shaped object.

[0015] 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. In addition, the dimension of the first internal electrode 41 in the direction along the second axis Y is smaller than the dimension of the element body 20 in the direction along the second axis Y. The dimensions of the second internal electrode 42 in each direction are approximately the same as those of the first internal electrode 41.

[0016] 1, the first internal electrodes 41 and the second internal electrodes 42 are positioned alternately in the direction along the third axis Z. That is, from the side surface 22C facing the third positive direction Z1 toward the third negative direction Z2, the first internal electrode 41, the second internal electrode 42, the first internal electrode 41, and the second internal electrode 42 are arranged in this order. In this embodiment, the distances between the internal electrodes in the direction along the third axis Z are equal.

[0017] As shown in Fig. 1, the five 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 second axis Y. On the other hand, as shown in Fig. 1, the first internal electrodes 41 are biased toward the first positive direction X1. Although not shown, the second internal electrodes 42 are biased toward the first negative direction X2.

[0018] Specifically, as shown in FIG. 1 , the end of the first internal electrode 41 on the first positive direction X1 side coincides with the end of the element body 20 on the first positive direction X1 side. Therefore, the end of the first internal electrode 41 on the first positive direction X1 side is exposed at the first end surface 22A. The end of the first internal electrode 41 on the first negative direction X2 side is located inside the element body 20 and does not reach the end of the element body 20 on the first negative direction X2 side. On the other hand, although not shown, the end of the second internal electrode 42 on the first negative direction X2 side coincides with the end of the element body 20 on the first negative direction X2 side. Therefore, the end of the second internal electrode 42 on the first negative direction X2 side is exposed at the second end surface. 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.

[0019] As shown in FIG. 1, the capacitor component 10 includes a first external electrode 61 and a second external electrode 62. The first external electrode 61 covers the first end face 22A and portions of the four side faces 22C of the element body 20 facing the first positive direction X1. That is, the first external electrode 61 is a five-sided electrode. As shown in FIG. 2, the first external electrode 61 has a first base electrode 61A, a first Ni layer 61B, and a first Sn layer 61C. The first base electrode 61A, the first Ni layer 61B, and the first Sn layer 61C are stacked in this order from the outer surface side of the element body 20. Note that FIG. 2 does not show the internal electrodes inside the element body 20.

[0020] The first base electrode 61A is laminated on a portion of the outer surface of the element body 20, including the first end face 22A. Specifically, the first base electrode 61A covers the first end face 22A and portions of the four side faces 22C of the element body 20 facing the first positive direction X1. In this embodiment, the first base electrode 61A is made of Cu. The first base electrode 61A may contain a polymer compound including inorganic carbon and organic carbon.

[0021] The first Ni layer 61B is laminated on the first base electrode 61A. That is, the first Ni layer 61B covers the first base electrode 61A from the outside. The first Ni layer 61B is mainly composed of Ni. The first Ni layer 61B is formed, for example, by electrolytic plating of Ni. Note that "main component" means that the content ratio of the target substance exceeds 50%. For example, the first Ni layer 61B has a Ni content ratio of more than 50 mol%. Note that the elements present in each layer of the first external electrode 61 and the concentration of each element can be observed using so-called TEM-EDX (energy dispersive X-ray spectroscopy).

[0022] The first Sn layer 61C is laminated on the first Ni layer 61B. That is, the first Sn layer 61C covers the first Ni layer 61B from the outside. The first Sn layer 61C is mainly composed of Sn. The first Sn layer 61C is formed by, for example, electrolytic plating of Sn.

[0023] The second external electrode 62 covers the second end face of the element body 20 and parts of the four side faces 22C facing the first negative direction X2. That is, the second external electrode 62 is a five-sided electrode. The second external electrode 62 does not reach the first external electrode 61 on the side face 22C, and is spaced apart from the first external electrode 61 in the direction along the first axis X. Furthermore, the central part of the side face 22C of the element body 20 in the direction along the first axis X is a part where the first external electrode 61 and the second external electrode 62 are not stacked.

[0024] Although not shown, the second external electrode 62 has a second base electrode, a second Ni layer, and a second Sn layer. The second base electrode, second Ni layer, and second Sn layer of the second external electrode 62 have the same configurations as the first base electrode 61A, first Ni layer 61B, and first Sn layer 61C of the first external electrode 61.

[0025] <About the mounting structure of capacitor components> Next, a description will be given of a mounting structure 100 between the capacitor component 10 and the substrate 70. Note that, although a mounting structure between the first external electrode 61 of the capacitor component 10 and the substrate 70 will be described below, the same applies to a mounting structure between the second external electrode 62 and the substrate 70.

[0026] As shown in FIG. 2, the substrate 70 has a substrate body 71 and lands 72. The substrate body 71 is made of an insulating material such as synthetic resin. The substrate body 71 is plate-shaped. The lands 72 are laminated on the main surface of the substrate body 71. The lands 72 are portions for mounting the capacitor component 10 described above. Although not shown in the figure, the lands 72 are connected to wiring or the like extending on the substrate body 71.

[0027] Before the capacitor component 10 is mounted, the land 72 has an underlayer 73, a first plating layer 74, and a second plating layer. The underlayer 73, the first plating layer 74, and the second plating layer are stacked in this order from the substrate main body 71 side. The underlayer 73 is mainly composed of Cu. The first plating layer 74 is mainly composed of Ni. The second plating layer is mainly composed of Au. These layers may contain elements other than the main component elements. The elements present in each layer of the land 72 and the concentration of each element can be observed using so-called TEM-EDX.

[0028] 2, the capacitor component 10 is bonded onto a land 72 of a substrate 70 via solder 80. Specifically, when the capacitor component 10 is mounted on the land 72 of the substrate 70, one surface of the first external electrode 61 of the capacitor component 10 faces the land 72. A portion of the solder 80 is interposed between the land 72 and the first external electrode 61 facing the land 72.

[0029] Note that Au, which is the main component of the second plating layer of the land 72, disperses in the solder 80 when the capacitor component 10 is mounted on the substrate 70 with the solder 80. Therefore, after the capacitor component 10 is mounted, the second plating layer of the land 72 does not have a clear layer structure and is in a state where it is integrated with the solder 80. Meanwhile, a first alloy layer 84 is formed in the boundary region between the first plating layer 74 and the solder 80. The first alloy layer 84 is an alloy containing Cu contained in the particles 82 described below, Ni contained in the first plating layer 74, and Sn contained in the solder 80. Note that the term "alloy" as used here is a concept that includes intermetallic compounds, solid solutions, and eutectic states.

[0030] As described above, the main component of the first Sn layer 61C is Sn. Therefore, when the capacitor component 10 is mounted on the substrate 70 with the solder 80, the first Sn layer 61C melts together with the solder 80. As a result, the first Sn layer 61C is integrated with the solder 80 and no longer exists as a distinct layer. Meanwhile, a second alloy layer 85 is formed between the first Ni layer 61B and the solder 80. The second alloy layer 85 is an alloy containing Cu contained in the particles 82 (described later), Ni contained in the first Ni layer 61B, and Sn contained in the solder 80.

[0031] Furthermore, when viewed in a direction perpendicular to the main surface of the substrate 70, the land 72 protrudes outward from the outer edge of the first external electrode 61. Specifically, a portion of the land 72 is located on the first positive direction X1 side of the first end face 22A of the first external electrode 61, which faces the first positive direction X1. Although not shown, a portion of the land 72 protrudes on both sides of the outer edge of the first external electrode 61 in the direction along the second axis Y. In other words, when the mounting structure 100 is viewed in a direction perpendicular to the main surface of the substrate 70, a portion of the outer periphery of the land 72 is located outside the outer periphery of the first external electrode 61. Note that a portion of the outer periphery of the land 72 may be located inside the outer periphery of the first external electrode 61. Reflecting this positional relationship between the first external electrode 61 and the land 72, a portion of the solder 80 has a fillet portion 90 that protrudes beyond the outer edge of the capacitor component 10. In other words, when the mounting structure 100 is viewed from a direction perpendicular to the main surface of the substrate 70, a fillet portion 90, which is part of the solder 80, is present in a portion of the outer periphery of the land 72 that is outside the outer periphery of the first external electrode 61. This fillet portion 90 is in contact with the first end face 22A of the first external electrode 61 and the side face 22C of the first external electrode 61 that faces in a direction along the second axis Y. The fillet portion 90 has a shape that widens as it approaches the land 72 side.

[0032] The solder 80 has a solder body 81 and a plurality of particles 82. The melting point of the solder body 81 is, for example, 130°C or higher and 200°C or lower. The melting point of the particles 82 may be higher than the melting point of the solder body 81. The melting point of Cu is 1084°C. In FIG. 2, only some of the particles 82 are labeled with reference numerals. The main component of the solder body 81 is an alloy made of Sn and Bi. Specifically, the material of the solder body 81 is Sn-58Bi. The main component of the particles 82 is Cu. In other words, the particles 82 are copper particles. The median particle diameter of the particles 82 is 7.5 μm or higher and 30 μm or lower. The content of the Cu component of the particles 82 in the solder 80 is 0.01 wt% or higher and 10 wt% or lower with respect to the total weight of the solder 80. In a direction parallel to the main surface of the land 72, the particles 82 are distributed in the solder 80 all over the land 72. Therefore, the particles 82 are present not only between the first external electrode 61 and the land 72, but also in the fillet portion 90 of the solder 80.

[0033] <About the manufacturing method of the mounting structure> The manufacturing method of the mounting structure 100 includes a substrate preparation step, a solder application step, a mounting step, and a heating step.

[0034] First, a substrate preparation step is performed as shown in FIG. 3. In the substrate preparation step, a substrate 70 is placed in a predetermined position. The substrate 70 has a pair of lands 72 for each capacitor component 10 to be mounted. The pair of lands 72 are arranged at a distance from each other in a direction parallel to the main surface of the substrate body 71. The distance between the pair of lands 72 is shorter than the distance from the first end face 22A to the second end face of the capacitor component 10 in the direction along the first axis X. The area of ​​the main surface of each land 72 is larger than the area of ​​the surface of the first external electrode 61 of the capacitor component 10 facing the third negative direction Z2.

[0035] Next, as shown in FIG. 4, a solder application process is performed. In the solder application process, a solder paste containing solder 80 is applied onto each land 72 on the substrate 70. In this embodiment, the solder paste containing solder 80 is applied to the entire main surface of each land 72. The solder paste is produced by mixing and stirring a particulate solder body 81 made of Sn-58Bi, which is the base of the solder 80, with particles 82, flux, a thixotropic agent, and the like. The content of Cu in the particles 82 in the solder 80 is 0.01 wt% or more and 10 wt% or less with respect to the total weight of the solder 80. The median particle diameter of the particles 82 is 7.5 μm or more and 30 μm or less.

[0036] Next, a mounting process is performed as shown in Fig. 5. In the mounting process, the capacitor component 10 is placed on a pair of lands 72. Specifically, the first external electrode 61 is placed on the main surface of one of the lands 72, and the second external electrode 62 is placed on the main surface of the other land 72. As described above, since the solder paste containing the solder 80 has already been applied to each land 72, when the capacitor component 10 is placed in the mounting process, the solder 80 is interposed between each land 72 and the capacitor component 10.

[0037] Next, as shown in FIG. 6 , a heating process is performed. In this heating process, the solder 80 is heated to melt. Specifically, the entire substrate 70 and capacitor component 10 are heated in a heating furnace. The heating temperature is set to a temperature at which the solder 80 melts but the particles 82 do not melt. The maximum heating temperature is set, for example, within a range of 150°C to 210°C. When the solder 80 melts at this temperature, the particles 82 settle toward the lands 72 due to their own weight. Therefore, the particles 82 on each land 72 are more numerous on the solder 80 closer to the land 72. In other words, the particles 82 are unevenly distributed toward the lands 72. Furthermore, when the solder 80 melts, it spreads over the surfaces of the first external electrode 61 facing the first positive direction X1, the second positive direction Y1, and the second negative direction Y2. As a result, a fillet portion 90 is formed in the solder 80. Similarly, a fillet portion 90 is also formed on the second external electrode 62.

[0038] <About the comparative test> The results of tests on the adhesive strength and impact resistance of capacitor components are described below. Mounting structure samples Nos. 1, 2, 3, 4, and 5, which will be described below, were subjected to the tests. The structures and materials of these samples conform to the structure and materials of the mounting structure 100 of the above embodiment, unless otherwise specified. Samples Nos. 1 and 5 are also samples prepared for comparison.

[0039] [Table 1]

[0040] As shown in Table 1, the solder material for samples 1, 2, 3, 4, and 5 is Sn-58Bi. Of samples 1, 2, 3, 4, and 5, the solder for samples 2, 3, and 4 contains Cu particles. The median diameter of the Cu particles in the solder for samples 2, 3, and 4 is 7.5 μm. For sample 2, the Cu particle content in the solder is 1 wt% of the total solder weight. For sample 3, the Cu particle content in the solder is 2 wt% of the total solder weight. For sample 4, the Cu particle content in the solder is 5 wt% of the total solder weight. For sample 1 and 5, the Cu particle content in the solder is 0%. In samples Nos. 1, 2, 3, and 4, the land of the substrate has a two-layer structure consisting of a plating layer mainly composed of Ni and a plating layer mainly composed of Au, in that order from the substrate body side. In sample No. 5, the land of the substrate has a single-layer structure consisting of a plating layer mainly composed of Cu.

[0041] In this test, samples 1, 2, 3, 4, and 5 were exposed to an atmosphere at 125°C for 100 hours. After that, the degree to which the bonding strength of the capacitor components to the substrate had decreased compared to the initial state was investigated for each sample. Here, "initial state" refers to the state before each mounting structure was exposed to an atmosphere at 125°C. In this comparative test, the bonding strength of the capacitor components to the substrate was evaluated from two perspectives: adhesive strength and impact resistance.

[0042] The method for evaluating adhesive strength in this comparative test is explained below. Adhesion strength in this comparative test is the load required to destroy the mounting structure when a load is applied to a capacitor component in a direction parallel to the main surface of the board. Here, destruction of the mounting structure refers to destruction of the component, bonding material, or land, resulting in loss of connection with the board land. If the adhesive strength of each mounting structure after 100 hours of exposure to a high temperature of 125°C is 95% or more of its initial adhesive strength, it is rated as A. If the adhesive strength of each mounting structure after 100 hours of exposure to a high temperature of 125°C is 70% or more but less than 95% of its initial adhesive strength, it is rated as B. If the adhesive strength of each mounting structure after 100 hours of exposure to a high temperature of 125°C is less than 70% of its initial adhesive strength, it is rated as C.

[0043] The method for evaluating impact resistance in this comparative test is explained below. Impact resistance in this comparative test is the percentage of mounting structures in which no electronic components fell off after a specified impact was applied 1,000 times to a group of mounting structures. If the impact resistance of each mounting structure after being exposed to a high temperature of 125°C for 500 hours is 95% or more of its initial impact resistance, it is rated as A. If the impact resistance of each mounting structure after being exposed to a high temperature of 125°C for 500 hours is 70% or more but less than 95% of its initial impact resistance, it is rated as B. If the impact resistance of each mounting structure after being exposed to a high temperature of 125°C for 500 hours is less than 70% of its initial impact resistance, it is rated as C.

[0044] According to this comparative test, the mounting structures of sample numbers 2, 3, and 4 were all rated A for adhesive strength and impact resistance. In contrast, the mounting structures of sample numbers 1 and 5 were all rated B or lower for adhesive strength and impact resistance. In other words, the Cu particles present in the solder of the mounting structure suppress a decrease in the bonding strength between the substrate of the mounting structure and the electronic component after exposure to high temperatures.

[0045] <Effects of the embodiment> The effects of this embodiment will be described. (1) In the above embodiment, the external electrodes of the capacitor component 10 and the lands 72 of the substrate 70 contain Ni. Therefore, the Ni component and the Sn contained in the solder 80 are alloyed during the manufacturing process. This Ni-Sn alloy grows thick when the substrate 70 and the capacitor component 10 are exposed to high temperatures. Because the Ni-Sn alloy is more brittle than the solder body 81 of the solder 80, if the Ni-Sn alloy layer is formed thick, the bonding strength of the capacitor component 10 to the substrate 70 will decrease.

[0046] In this regard, the particles 82 in the solder 80 are distributed not only between each external electrode of the capacitor component 10 and the land 72 of the substrate 70, but also over the entire main surface of the land 72. Cu, which is the main component of the particles 82, suppresses the growth of the Ni-Sn alloy described above. Therefore, according to the above embodiment, a decrease in the reliability of the bond between the land 72 and the capacitor component 10 is suppressed.

[0047] (2) The presence of Cu particles or Cu compound particles under the product electrodes or near the lands ensures the solder thickness under the product electrodes, improving joint reliability. (3) In the above embodiment, Cu contained in the particles 82 does not melt in the solder 80, but exists as particles 82 in the solder 80. This allows the effect of Cu to be obtained while maintaining joint reliability. Furthermore, because the particles 82 are unevenly distributed near the lands, the effect of improving joint reliability can be obtained efficiently even with a small blending amount.

[0048] (4) By setting the Cu content of the particles 82 in the solder 80 to 0.01 wt% or more relative to the total weight of the solder 80, the particles 82 are more likely to spread throughout the lands 72. This effectively suppresses the decrease in bonding strength described above. On the other hand, if the Cu content of the particles 82 in the solder 80 is set to more than 10 wt% relative to the total weight of the solder 80, an excessive number of particles 82 may be exposed on the surface of the solder 80 after the capacitor component 10 is mounted. This large amount of exposed particles 82 may adversely affect the bonding strength of the solder body 81. However, if the Cu content of the particles 82 is 10 wt% or less, as in the above embodiment, this concern is unlikely to become apparent.

[0049] (5) By setting the particle size of the particles 82 to 7.5 μm or more, the effect of maintaining the joint reliability between the substrate 70 and the capacitor component 10 is sufficiently ensured. Furthermore, if the particle size of the particles 82 is larger than 30 μm, depending on the sizes of the capacitor component 10 and the lands 72, the solder joint between the substrate 70 and the capacitor component 10 may become unstable. For this reason, it is preferable that the particle size of the particles 82 be 7.5 μm or more and 30 μm or less.

[0050] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0051] The shape of the element body 20 is not limited to a rectangular parallelepiped. The first external electrode 61 is not limited to a five-sided electrode as shown in the example of the above embodiment. For example, there may be a side surface 22C that does not have a first external electrode 61. For example, the first external electrode 61 does not have to have a first end surface 22A. Regardless of the shape of the first external electrode 61, it is sufficient that electrical connection between the land 72 and the capacitor component 10 is ensured. The same applies to the second external electrode 62.

[0052] While the above embodiment illustrates an example in which a capacitor component 10 is used as an electronic component, the type of electronic component is not limited to a multilayer ceramic capacitor. The configuration of the particles 82 of the solder 80 in the above embodiment can be applied to any electronic component having an element body 20 and external electrodes. Examples of such electronic components include piezoelectric components, thermistors, and inductors. Furthermore, the element body 20 of the electronic component is not limited to being made of a dielectric material, and may be made of, for example, a magnetic material, a piezoelectric material, or the like.

[0053] 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 five. The same applies to the second internal electrodes 42.

[0054] The particles 82 may have a core and a Cu coating layer covering the core. In such a case, the core may be made of a metal other than Cu, ceramic, or the like. However, it is preferable that the melting point of the particles 82 is higher than the melting point of Cu. In this way, by replacing the material of the core of the particles 82 with a material other than Cu, the amount of Cu used can be reduced.

[0055] The particles 82 may not be pure copper particles but may be particles containing Cu, such as copper compound particles. The copper compound particles are, for example, Cu-Sn alloys such as Cu6Sn5 and Cu3Sn.

[0056] The composition of particles 82 may change before and after heating. Heating in a heating furnace may cause some or all of the Cu component of particles 82 to be alloyed with the Sn component of solder body 81. In such a case, particles 82 may be replaced with particles of an alloy of Cu and Sn. Also, two layers of particles may be present: particles 82 and an alloy of Cu and Sn. In other words, it is sufficient that solder 80 contains particles containing Cu. The same applies to the case where the Cu component of particles 82 is alloyed with a metal component other than Sn.

[0057] The material of the solder body 81 is not limited to Sn-58Bi, as long as it contains Sn. For example, the solder body 81 may contain a different Bi content or one or more different elements. Examples of different elements include Ag, Au, Sb, Zn, In, Co, Cu, Pb, and Ni. Note that the Sn content of the solder body 81 is preferably 40 wt% or more and 70 wt% or less.

[0058] The particle size of the particles 82 may be less than 7.5 μm in median diameter or greater than 30 μm. The main components of the first plating layer 74 and the second plating layer 75 of the land 72 are not limited to the example of this embodiment. The main component of the first plating layer 74 does not have to be Ni. Furthermore, the main component of the second plating layer 75 does not have to be Au. It is sufficient that electrical connection between the land 72 and the electronic component is ensured. However, if either the land 72 or the first external electrode 61 contains Ni, an alloy of Sn and Ni originating from the solder 80 may be generated, which may result in a problem of reduced joint strength.

[0059] The main component of the underlayer 73 of the land 72 is not limited to the example of this embodiment. The first external electrode 61 may be made of any material. The first external electrode 61 may have a one-layer structure, a two-layer structure, or a multi-layer structure of four or more layers. The same applies to the second external electrode 62.

[0060] The content of the Cu component in the particles 82 in the solder 80 may be less than 0.01 wt % or more than 10 wt % with respect to the total weight of the solder 80 . The mounting structure 100 does not have to have a distinct fillet portion 90. The fillet portion 90 does not have to have a shape that widens toward the substrate 80, as in the case of the fillet portion 90 of this embodiment, as long as the solder 80 has a portion that protrudes beyond the outer edge of the capacitor component 10. The same applies to the second external electrode 62.

[0061] The region where the fillet portion 90 exists is not limited to the example of this embodiment. When viewed from a direction perpendicular to the main surface of the substrate 70, the fillet portion 90 may exist in one or more directions selected from the first positive direction X1, the second positive direction Y1, and the second negative direction Y2.

[0062] <Additional Notes> The technical ideas that can be understood from the above-described embodiment and modified examples will be described. [1] A mounting structure for an electronic component comprising: a substrate having lands; an electronic component having an element body and external electrodes laminated on the outer surface of the element body; and solder containing Sn, wherein at least one of the external electrodes and the lands contains Ni; the external electrodes are joined to the lands with the solder; the solder contains particles containing Cu, and when viewed in a direction perpendicular to the substrate, has a portion that protrudes outward from the outer edge of the electronic component, and the particles are located between the external electrodes and the lands and in the protruding portion.

[0063] [2] The electronic component mounting structure according to [1], wherein the particle has a core and a Cu coating layer covering the core. [3] The electronic component mounting structure according to [1] or [2], wherein the content of the Cu component of the particles in the solder is 0.01 wt% or more and 10 wt% or less with respect to the total weight of the solder.

[0064] [4] The electronic component mounting structure according to any one of [1] to [3], wherein the particle diameter of the particles is 7.5 μm or more and 30 μm or less. [5] A mounting structure for an electronic component according to any one of [1] to [4], wherein the element body is rectangular, the lands contain Ni and Au, the external electrodes contain Ni and Sn, the external electrodes are provided on the entirety of one end face and one or more faces selected from four side faces adjacent to the end face among six flat faces that constitute the outer surface of the element body, and the solder contains Sn and Bi. [Explanation of symbols]

[0065] 20...Base body 22…Plane 22C…side 70...Substrate 72...Rand 82…Particle 100...Mounting structure

Claims

1. a substrate having lands; an electronic component having an element body and external electrodes laminated on the outer surface of the element body; a solder containing Sn, At least one of the external electrode and the land contains Ni, the external electrodes are joined to the lands with the solder; the solder contains particles containing Cu, and has a portion that protrudes outward from an outer edge of the electronic component when viewed in a direction perpendicular to the substrate; The particles are located between the external electrode and the land and in the protruding portion. Mounting structure for electronic components.

2. The particle has a core and a Cu coating layer covering the core. The electronic component mounting structure according to claim 1 .

3. The content of the Cu component of the particles in the solder is 0.01 wt % or more and 10 wt % or less with respect to the total weight of the solder. The electronic component mounting structure according to claim 1 .

4. The particle size of the particles is 7.5 μm or more and 30 μm or less. The electronic component mounting structure according to claim 1 .

5. The element body has a rectangular parallelepiped shape, the land includes Ni and Au; the external electrodes contain Ni and Sn, the external electrodes are provided on an entire end face of one of six flat faces constituting the outer surface of the element body and on one or more faces selected from four side faces adjacent to the end face, The solder contains Sn and Bi. The electronic component mounting structure according to claim 1 .

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