Coil component

Abstract

To improve adhesion between an external electrode and a conductor.SOLUTION: A coil component according to an embodiment includes a magnetic substrate, a conductor provided inside or on the surface of the magnetic substrate, and an external electrode provided on the outer surface of the magnetic substrate, the external electrode including a base electrode to which an end of the conductor is joined at a joint portion, the joint portion extends over the same area as the end of the conductor, and the area proportion of the crystal planes other than (111) is greater than the area proportion of the (111) crystal plane.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a coil component. [Background technology]

[0002] Due to environmental changes such as the increasing electrification of vehicles, the number of electronic components used in products is increasing and the applications for electronic components are expanding. This situation is common to many electronic components, and is also true for wire-wound coil components, in which a conductor wire is wound around a magnetic substrate. However, due to constraints such as assembly precision, wire-wound coil components have not been as miniaturized as other types of electronic components. However, even wire-wound coil components need to be miniaturized, and thinner conductor wires are also required.

[0003] On the other hand, as electronic components become smaller, components and solder are more susceptible to damage caused by stresses generated by bending of the mounting board and temperature changes, which has led to a demand for measures to protect coil components from stresses. For example, Patent Document 1 proposes a coil component in which the adhesion strength of the bottom electrode portion to the component body is lower than the adhesion strength of the end electrode portion to the component body, and when an external force is applied to the external electrode, the bottom electrode portion, which is part of the external electrode, moves relative to the component body to distribute the stress. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-041075 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the technology of Patent Document 1, a portion of the external electrode moves due to stress, causing expansion and contraction stress to be applied to the conductor. In particular, in the case of coil components using thin conductor wires, the movement of the external electrode increases the load on the conductor wires. The ends of the conductor wires are joined to the external electrode, and if the load on the conductor wires increases, the joint between the conductor wires and the external electrode may not be able to withstand the load. For this reason, there is a demand for improved adhesion between the external electrode and the conductor. As components become smaller, there is a demand for improved adhesion between the external electrode and the conductor not only in wire-wound coil components but also in multilayer coil components.

[0006] In view of the above circumstances, an object of the present invention is to improve the adhesion between an external electrode and a conductor. [Means for solving the problem]

[0007] In order to solve the above problem, a coil component according to one embodiment of the present invention comprises a magnetic base, a conductor provided inside or on the surface of the magnetic base, and an external electrode provided on the outer surface of the magnetic base, the external electrode including a base electrode to which an end of the conductor is joined at a joint, the joint extending over the same area as the end of the conductor, and the area proportion of its crystal planes is such that the area proportion of crystal planes other than (111) is greater than the area proportion of the (111) crystal plane.

[0008] In the coil component according to one aspect of the present invention, the joint portion is sandwiched between the outer surface of the magnetic base and the end portion of the conductor. In a coil component according to one embodiment of the present invention, the base electrode has a first base electrode around the joint, and the area ratio of the crystal planes of the first base electrode is such that the area ratio of crystal planes other than (111) is greater than the area ratio of the (111) crystal plane. According to a coil component of one embodiment of the present invention, the base electrode has a second base electrode around the first base electrode, and the area ratio of the crystal planes of the second base electrode is such that the area ratio of the (111) crystal plane is greater than the area ratio of crystal planes other than (111). In a coil component according to one aspect of the present invention, the external electrode has a conductive resin layer containing metal particles and resin on the outside of the joint.

[0009] In the coil component according to one aspect of the present invention, the conductive resin layer extends over an area wider than the area of ​​the joint. In the coil component according to one aspect of the present invention, the conductive resin layer covers the end portion of the conductor. In the coil component according to one aspect of the present invention, the external electrodes have plating layers on their surfaces. In a coil component according to one embodiment of the present invention, whether the area ratio of the crystal planes other than the (111) plane is greater than the area ratio of the (111) crystal plane is determined based on cross-sectional observation of the joint using an electron backscattering method. [Effects of the Invention]

[0010] According to the present invention, the adhesion between the external electrodes and the conductors can be improved. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing a coil component according to an embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4A] FIG. 2 is a diagram schematically illustrating the microscopic structure of the bonding surface of the bonding portion. [Figure 4B] FIG. 2 is a diagram schematically illustrating the structure of a joint before joining. [Figure 4C] FIG. 2 is a diagram schematically illustrating the structure of the bonding surface after bonding. [Figure 5] 10 is a longitudinal cross section showing a modified example in which the orientation of the drum core is different. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. [Figure 7] 10 is a longitudinal cross section showing a modified example of a stacked type. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. [Figure 9] FIG. 1 is a diagram showing a first example of an E-core type magnetic substrate. [Figure 10] FIG. 10 is a diagram showing a second example of an E-core type magnetic substrate. [Figure 11] FIG. 10 is a diagram showing a first modified example in which the structure of the external electrodes is different. [Figure 12] FIG. 10 is a diagram showing a second modified example in which the structure of the external electrodes is different. [Figure 13] FIG. 10 is a diagram showing a modified example in which the range of the joint is narrow. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the present invention, and not all of the combinations of features described in the embodiments are necessarily essential to the configuration of the present invention. The configuration of the embodiments may be modified or changed as appropriate depending on the specifications of the device to which the present invention is applied and various conditions (such as usage conditions and usage environment).

[0013] The technical scope of the present invention is defined by the claims and is not limited by the individual embodiments described below. The drawings used in the following description may differ in scale and shape from the actual structure to make each configuration easier to understand. The correspondence between the drawings may also differ in some places to simplify the description. Components shown in previously described drawings may be referenced as appropriate in the description of subsequent drawings.

[0014] <One embodiment of the coil component> FIG. 1 is a perspective view showing a coil device 100 according to one embodiment of the present invention. The coil component 100 is mounted on a substrate 200. The substrate 200 is provided with, for example, two land portions 201. The coil component 100 has, for example, two external electrodes 12. The coil component 100 is mounted on the substrate 200 by joining each external electrode 12 and each land portion 201 with solder.

[0015] The circuit board 10 includes a coil component 100 and a substrate 200 on which the coil component 100 is mounted. The circuit board 10 is included in a variety of electronic devices. Examples of electronic devices that include the circuit board 10 include automotive electrical components, servers, board computers, and various other electronic devices.

[0016] The coil component 100 may be an inductor, a transformer, a filter, a reactor, or any of various other coil components. The coil component 100 may be a coupled inductor, a choke coil, or any of various other magnetically coupled coil components. The coil component 100 may be, for example, an inductor used in a DC / DC converter. The uses of the coil component 100 are not limited to those explicitly described in this specification.

[0017] In this specification, unless otherwise understood in the context, the directions will be described based on the "L axis" direction, the "W axis" direction, and the "H axis" direction in Figure 1, which will be referred to as the "length" direction, the "width" direction, and the "height" direction, respectively. The coil device 100 has, for example, a rectangular parallelepiped outer shape. That is, the coil device 100 has outer surfaces at both ends in the length direction L, both ends in the height direction H, and both ends in the width direction W.

[0018] The rectangular parallelepiped coil device 100 has sides with a length L dimension in the range of 1.0 to 4.5 mm, a width W dimension in the range of 0.5 to 3.2 mm, and a height H dimension in the range of 0.5 to 1.0 mm. The height H dimension is smaller than the length L dimension, and the height H dimension is smaller than the width W dimension.

[0019] The outer surfaces of the coil device 100 may be flat, curved, or have a stepped portion. The eight corners and twelve ridges of the coil device 100 may be rounded. In this specification, even when the outer surface of the coil device 100 is partially curved or has steps, or when the corners or ridges of the coil device 100 are rounded, such a shape may be referred to as a "rectangular parallelepiped shape." In other words, in this specification, when we refer to a "rectangular parallelepiped" or a "rectangular parallelepiped shape," it does not mean a "rectangular parallelepiped" in the strict mathematical sense.

[0020] <Coil component structure> Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1, and Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. The following description will be made with reference to Figs. 1 to 3. As an example, the coil device 100 may have a magnetic base 11, an external electrode 12, a conductor 14 inside the magnetic base 11, and an exterior part 13 in addition.

[0021] The magnetic base 11 in this embodiment is referred to as a drum core, and has a flange 111 and a winding core 112. The magnetic base 11 has side surfaces 103 at both ends in the length direction L. The magnetic base 11 also has a bottom surface 101 at one end of the flange 111 in the height direction H, and a top surface 102 at the other end in the height direction H. The magnetic base 11 also has a front surface 104 at one end of the flange 111 in the width direction W, and a rear surface 105 at the other end in the width direction W. The bottom surface 101 is a mounting surface that faces the substrate 200 when the coil component 100 is mounted on the substrate 200.

[0022] The top surface 102 and the bottom surface 101 are positioned back to back. "Back to back" means that the surfaces face outward in opposite directions. The top surface 102 is adjacent to the side surface 103, the front surface 104, and the rear surface 105, and the bottom surface 101 is adjacent to the side surface 103, the front surface 104, and the rear surface 105. "Adjacent" means that there is no other surface between the surfaces, but rather a ridge line between them. In the example shown here, the adjacent surfaces are positioned so that they intersect at right angles.

[0023] The magnetic substrate 11 includes a magnetic material and may also include a non-magnetic material. Examples of magnetic materials that can be used for the magnetic substrate 11 include ferrite and soft magnetic metals. Examples of non-magnetic materials that can be used for the magnetic substrate 11 include alumina and glass. The magnetic material for the magnetic substrate 11 may be any of various crystalline or amorphous metallic magnetic materials, or a combination of crystalline and amorphous materials.

[0024] A crystalline metal magnetic material that can be used as the magnetic material for the magnetic substrate 11 is, for example, a crystalline metal material that contains 50 wt% or more, or 85 wt% or more, of Fe as the main component and one or more elements selected from the group consisting of Si, Al, Cr, Ni, Ti, and Zr. An amorphous metal magnetic material that can be used as the magnetic material for the magnetic substrate 11 is, for example, an amorphous metal material that contains either B or C in addition to any one of Si, Al, Cr, Ni, Ti, and Zr.

[0025] Pure iron consisting of Fe and unavoidable impurities can be used as the magnetic material for the magnetic substrate 11. A material combining pure iron consisting of Fe and unavoidable impurities with various crystalline or amorphous alloy metal magnetic materials can also be used as the magnetic material for the magnetic substrate 11. The material of the magnetic substrate 11 is not limited to those explicitly stated in this specification, and any material known as a substrate material can be used.

[0026] The magnetic base 11 is produced, for example, by mixing powder of the above-mentioned magnetic or non-magnetic material with a lubricant, filling the mixture into the cavity of a molding die and press-molding it to produce a green compact, and then heat-treating the green compact. The green compact may be ground to adjust its shape before heat-treating. The magnetic base 11 may also be formed by a molding method.

[0027] Alternatively, magnetic base 11 can be produced by mixing powder of the above-mentioned magnetic or non-magnetic material with resin, glass, or an insulating oxide (e.g., Ni-Zn ferrite or silica), molding this mixed material using a lamination method or the like, and then heat treating it. Depending on the raw materials used, magnetic base 11 can be heat-cured at a temperature of 200°C or less, or sintered at a temperature of 600°C or higher or 1100°C or higher.

[0028] It is preferable that the magnetic base 11 is not affected by heat when forming the external electrodes 12. Specifically, it is better to have as little resin as possible, which is easily affected by heat when forming the external electrodes, and it is desirable that the proportion of resin be less than 1% of the volume of the magnetic base 11, for example.

[0029] As an example, the conductor 14 is a metal conductor with an insulating coating on its surface wound around the winding core 112 of the magnetic substrate 11. The conductor 14 has a winding portion that winds around the winding core 112. The conductor wire of the conductor 14 is made of a metal material with excellent conductivity. For example, one or more of Cu, Ag, and Al, or an alloy of these metals, can be used as the metal material for the conductor 14. A conductor with low resistance is used, and for example, the filling rate of the metal material is 90% or more, or even 98% or more. As the insulator used as the coating, a common material such as polyamideimide, polyamide, polyimide, or polyurethane is selected.

[0030] The conductor 14 may have a cross-sectional shape of, for example, a circle, a rectangle, or an oval. It is desirable to use a general-purpose conductor as the conductor 14 for reasons such as low resistance and the ability to accommodate a variety of applications. The number of turns in the winding portion of the conductor 14 is, for example, 1.5 turns or more and 10.5 turns or less. The winding portion may have a planar or spiral shape. The winding portion may have, for example, two turns facing each other to form a single assembly. Figures 2 and 3 show an example of a so-called vertically wound winding portion in which the conductor is wound along the side surface 103 of the magnetic substrate 11.

[0031] The conductor 14 has an extension portion (not shown) for electrical conduction with the outside, and an end portion 141 of the extension portion is joined to a later-described base electrode 121 of the external electrode 12. By joining the end portion 141, the external electrode 12 is electrically connected to the conductor 14. One method for joining the base electrode 121 and the end 141 of the conductor 14 is to place the end 141 on the base electrode 121 and apply heat to the base electrode 121 and the end 141. The applied heat melts at least a portion of the base electrode 121 and the end 141, thereby joining the two metals of the base electrode 121 and the end 141.

[0032] Heating for bonding is performed at a temperature lower than the temperature at which the two metals are completely melted, or the heating time is limited to a time shorter than the complete melting point. The bonding temperature is lower than the sintering temperature of the base electrode 121, which will be described later. If the time is limited, the heating temperature may be close to the complete melting temperature. For example, the bonding temperature between the conductor 14 and the base electrode 121 is set to be 0.5 to 0.8 times the melting point of the metal of the conductor 14 in Kelvin degrees.

[0033] The heating method for joining is, for example, laser irradiation or pressurized heating with a heater tip on the end 141 of the conductor 14. 2 Lasers are used when the cross-sectional area of ​​the conductor is larger than 0.008 mm. 2A heater chip is used for the following conductor 14. The selection of the heating method is also influenced by the heat conduction during bonding. 3 For larger cases, lasers are used, and 50 mm 3 Heater chips are used in the following cases:

[0034] The exterior part 13 is made of a resin material containing ceramic particles and metal particles, and covers the outer periphery of the wound part of the conductor 14 to protect the conductor 14. The exterior part 13 is formed, for example, by applying a paste-like resin material to the outer periphery of the peripheral part of the conductor 14. The coil device 100 includes, for example, two external electrodes 12. The external electrodes 12 shown in Figs. 1 to 3 are, for example, electrodes of a type called a two-surface electrode, and are provided, for example, on the bottom surface 101 and side surface 103, which are outer surfaces of the magnetic base 11. The external electrodes 12 may also be of a type called a one-surface electrode.

[0035] Note that "provided on a surface" means provided at a location that is visible when looking at the surface, and may be provided so as to protrude outward from the surface in a direction perpendicular to the surface, or may be provided so as to dig inward from the surface.

[0036] <External electrode structure> The external electrode 12 has, for example, a base electrode 121, a conductive resin layer 123, and a plating layer 124. The base electrode 121 has, for example, a joint 121a to which an end 141 of the lead portion of the conductor 14 is joined, a first base electrode 121b around the joint 121a, and a second base electrode 121c. The base electrode 121 does not necessarily have to have the second base electrode 121c. When the external electrode 12 has the conductive resin layer 123, the conductive resin layer 123 is provided on the outside of the base electrode, and when the external electrode 12 has the plating layer 124, the plating layer 124 is provided on the outside of the base electrode 121 and the conductive resin layer 123.

[0037] The base electrode 121 is made of Cu, Ag, or Pd and is sintered. Alternatively, the base electrode 121 may be made of an alloy containing Cu, Ag, or Pd, or may include a glass material. The joint 121a is a region sandwiched between the outer surface of the magnetic substrate 11 and the end 141 of the conductor 14. When the crystal plane structure is divided into (111) crystal planes and crystal planes other than (111), the joint 121a includes at least crystal planes other than (111). When comparing the area proportions of the (111) crystal planes and the crystal planes other than (111), the area proportion of the crystal planes other than (111) in the joint 121a is greater than the area proportion of the (111) crystal planes.

[0038] FIG. 4A is a diagram schematically showing the microscopic structure of the joint 121a. The joint 121a is a mixture of, for example, Ag crystal planes 211 and 212 as a conductive material, glass 214 as an insulator other than a conductive material, and voids 215. A large amount of glass 214 is provided between the base electrode 121 and the outer surface of the magnetic substrate, providing strength at this interface.

[0039] The Ag crystal faces 211, 212 of the bonding portion 121a include, for example, a (111) crystal face 211 and other crystal faces 212 (a (100) crystal face and a (110) crystal face). The area ratio of the (111) crystal face 211 of the bonding portion 121a is smaller than the area ratio of the other crystal faces 212 (the sum of the (100) crystal face and the (110) crystal face). The area ratios of the crystal faces 211, 212 may be determined by observing a cross section of the bonding portion 121a at 2000x magnification using an electron backscattering method, or may be determined from a length ratio.

[0040] As in the joint 121a, the area ratio of the (111) crystal plane 211 in the first base electrode 121b is smaller than the area ratio of the other crystal planes 212 (the sum of the (100) crystal plane and the (110) crystal plane). On the other hand, in the second base electrode 121c, the area ratio of the crystal plane 212 is smaller than the area ratio of the (111) crystal plane 211.

[0041] Fig. 4A shows the structure of the bonding portion 121a, and here we will explain the structure of the bonding portion 121a (base electrode 121) before bonding and the structure of the bonding portion 121a (base electrode 121) after bonding. Fig. 4B shows the structure of the bonding portion 121a (base electrode 121) before bonding, and Fig. 4C shows the structure of the bonding portion 121a (base electrode 121) after bonding. As shown in Figure 4B, the base electrode 121 exhibits a three-dimensional surface structure resembling steps or contour lines due to solid-phase sintering of the Cu, Ag, and Pd raw material powders. The (111) crystal plane (reference numeral 211) is parallel to the base electrode 121 surface (the surface tangent to the surface designated by reference numeral 101 in Figure 2). On the other hand, crystal planes other than the (111) crystal plane (reference numeral 212) are exposed as step planes of the staircase-like or contour-like crystal planes, with a plane orientation different from that of the crystal plane (111).

[0042] 4B to the base electrode 121 (process of joining the joint 121a and the end 141), plastic deformation occurs in the step-like three-dimensional structure of the bottom electrode 121. Due to this plastic deformation, not only the crystal plane 211 but also the crystal planes 212 other than the (111) plane are oriented in the same plane direction, as shown in FIG. 4C, and a joint interface of the joint 121a is formed.

[0043] The base electrode 121 of the external electrode 12 is formed by applying a paste-like metal material containing metal particles to the outer surface of the magnetic base 11 and then sintering it. The metal material is a combination of metal particles of different shapes and sizes. For example, spherical particles may be combined with plate-like or scale-like particles, and for example, small spherical particles may be combined with large plate-like or scale-like particles in the longest direction. The sintering temperature of the joint 121a is set to, for example, 0.6 to 0.85 times the melting point of the metal of the joint 121a in Kelvin temperature.

[0044] The sintering of the metal material, at least at the joint 121a, is performed at a temperature that prevents the entire metal particles from sintering after sintering. For example, small metal particles in the metal material tend to melt easily on the surface and spread to surrounding metal particles, thereby reducing gaps and promoting densification. Large metal particles are difficult to melt, and sintering is performed at a temperature that prevents densification. Also, for example, plate-shaped, scale-shaped, and spherical particles may be combined, and depending on the shape, some particles with a large specific surface area will spread and be incorporated into the surrounding metal particles.

[0045] In this way, the densification of the metal material is incomplete or non-uniform at the joint 121a. In this embodiment, as a result, many crystal faces 212 other than the (111) crystal face 211 are formed. As will be described below, this improves the bonding strength at the bonding surface between the base electrode 121 and the end 141 of the conductor 14. For example, the filling rate of the metal material in the base electrode 121 is 60% or more and 85% or less.

[0046] Here, the (111) crystal face 211 is dense and stable as a metal, so metal diffusion between the conductor 14 and the joint 121a is unlikely to occur during joining. In contrast, the (100) crystal face 212 and the (110) crystal face 212 are not stable as crystals, so diffusion is likely to occur and they are more likely to receive metal that has diffused and moved.

[0047] That is, because the area ratio of the crystal planes 212 other than the (111) crystal planes 211 that are unstable as metals is greater than the area ratio of the (111) crystal planes 211 that are stable as metals, diffusion of the metals between the two and mutual movement of the metals due to diffusion is likely to occur between the joint 121a and the conductor 14, strengthening the bond at this interface. For this reason, even if, for example, restrictions on the thickness of the conductor 14 wire are relaxed and a thick wire that increases the area of ​​the bonding surface is used, metal diffusion is likely to occur throughout the entire joint 121a, improving the bond strength.

[0048] Returning to Figures 1 to 3, the explanation continues. The conductive resin layer 123 of the external electrode 12 contains a resin and a metal filler. In the conductive resin layer 123, the resin is, for example, a thermosetting resin, and the metal filler contains, for example, a metal with the same components as the base electrode 121. Examples of materials for the metal filler include Ag, Pd, Cu, Al, Ni, Sn, and alloys thereof, and of these, Ag or Cu is preferred.

[0049] The metal filler may be of one type alone or a combination of two or more types, and may have shapes such as spherical, elongated spheroidal, flat, and rod-like. A combination of rod-like and spherical, or a combination of rod-like, spherical, and flat, is particularly preferable. For example, the conductive resin layer 123 contains more flat metal fillers than other metal fillers to reduce resistance. The conductive resin layer 123 contains resin, such as epoxy resin, phenolic resin, and acrylic resin. The proportion of resin in the conductive resin layer 123 is 30 vol% or more and 70 vol% or less.

[0050] The conductive resin layer 123 sandwiches the end 141 of the conductor 14 between itself and the joint 121a. When the conductive resin layer 123 is provided in the external electrode 12, the presence of the conductive resin layer 123 helps to alleviate stress caused by distortion of the substrate 200, etc. The stress alleviation effect of the conductive resin layer 123 extends not only to the joint between the base electrode 121 and the end 141, but also to the drawn-out portion of the conductor 14 via the end 141. Therefore, defects caused by stress are suppressed even for conductors 14 made of thin wires.

[0051] The conductive resin layer 123 covers the outside of the end 141 of the conductor 14. Therefore, the conductive resin layer 123 holds the end 141 of the conductor 14 and suppresses the load of stress on the end 141 of the conductor 14. Furthermore, in the range of the first base electrode 121b shown in FIG. 3, the conductive resin layer 123 is present in contact with the first base electrode 121b. Therefore, the conductive resin layer 123 surrounds the periphery of the end 141 joined to the joint 121a. Furthermore, the conductive resin layer 123 is provided over an area wider than the bonding portion 121a, and covers the entire base electrode 121. Therefore, the effect of alleviating stress can be obtained regardless of the direction of the stress.

[0052] The plating layer 124 is provided on the surface of the external electrode 12, and as an example, covers the entire conductive resin layer 123. The plating layer 124 is made of a metal material with excellent conductivity. Examples of metal materials that can be used include Cu and Ag, and alternatively, Ni, Pd, and Sn. The plating layer 124 is formed in a layered structure, with layers made primarily of each metal material or layers that are partially alloyed with each other. The plating layer 124 is provided to increase the strength of soldering to the external electrode 12. Furthermore, the plating layer 124 can be replaced with a solder layer for ease of soldering.

[0053] <Modification> The following describes modifications of the above-described coil device 100. The following description focuses on differences from the above-described coil device 100, and omits redundant description of elements that are the same as elements that have already been described.

[0054] Figures 5 and 6 show modified examples in which the orientation of the drum core is different. Figure 5 shows a longitudinal section parallel to the H axis and L axis, and Figure 6 shows a section taken along line VI-VI in Figure 5.

[0055] 5 and 6, the magnetic base 11 in the modified coil device 300 is oriented such that one side of the flange 111 faces the bottom surface 101, which is the mounting surface. The other side of the flange 111 of the magnetic base 11 faces the top surface 102. The winding core 112 of the magnetic base 11 extends in the height direction H, and the conductor 14 is wound in a so-called horizontal manner, with the conducting wire wound along the bottom surface 101 and the top surface 102. The coil device 300 shown in FIG. 5 does not include an exterior portion 13, as an example.

[0056] 5 and 6, the external electrode 12 also includes a base electrode 121, a conductive resin layer 123, and a plating layer 124, and an end 141 of the lead portion of the conductor 14 is joined to a joint 121a. In the modification shown in FIGS. 5 and 6, the conductor 14 is thick, so the area of ​​the joint surface is large, but the joint strength is high because the joint 121a has the above-described crystal plane structure. In this case, the base electrode 121 has a first base electrode 121b provided around the joint 121a, and a second base electrode 121c provided so as to be spaced apart from the joint 121a.

[0057] The first base electrode 121b has the same crystal plane structure as the junction 121a, and the second base electrode 121c has a different crystal plane structure from the junction 121a. For example, in the second base electrode 121c, the area ratio of the (111) crystal plane is larger than the area ratio of crystal planes other than the (111) crystal plane. By having the base electrode 121 including the second base electrode 121c in this way, the external electrode 12 can obtain the required strength and resistance.

[0058] 7 and 8 are diagrams showing modified examples of the stacked type. Fig. 7 shows a longitudinal section parallel to the H axis and L axis, and Fig. 8 shows a section taken along line VIII-VIII in Fig. 7. 7 and 8 show a laminated type coil component 400. In the case of the laminated type coil component 400, the conductor 14 is provided inside the magnetic base 11, and the end 141 of the lead-out portion is exposed on the bottom surface 101 of the magnetic base 11.

[0059] 7 and 8 includes, as an example, an external electrode 12 called a five-sided electrode. The five-sided external electrode 12 extends from one side surface 103 to a bottom surface 101, a top surface 102, a front surface 104, and a rear surface 105. The external electrode 12 includes a base electrode 121, a conductive resin layer 123, and a plating layer 124, and the base electrode 121 has a first base electrode 121b around the joint 121a. In the case of the multilayer type coil component 400, the metal material of the base electrode 121 is applied to the exposed portion of the end 141 of the lead-out portion and then sintered. As a result, the base electrode 121 is formed and the end 141 is joined to the joint 121a.

[0060] In the coil component 400 shown in FIGS. 7 and 8, the joints 121a and the first base electrode 121b are formed only in the area overlapping the end portion 141, and the remaining base electrode 121 is the second base electrode 121c. When the areas of the joints 121a and the first base electrode 121b are limited and the area occupied by the second base electrode 121c in the base electrode 121 is large, the base electrode 121 as a whole has high strength and low resistance. Furthermore, when the area in which the second base electrode 121c is provided is not limited to the same surface as the first base electrode 121b but is provided across two surfaces, higher strength is achieved. In other words, the coil component 400 fabricated in this manner is connected to the conductor 14 by the joints 121a, and the strength required for the external electrode is achieved by the second base electrode 121c.

[0061] 9 and 10 are diagrams showing different E-core type magnetic substrates. 9 and 10 are magnetic substrates known as E-core types, and can be used in place of, for example, magnetic substrate 11 shown in FIGS. 1 to 3. E-core type magnetic substrates 410, 420 have a winding core 411 and a peripheral wall 412 that surrounds the periphery of winding core 411, and a circumferential groove 413 that goes around winding core 411 is formed between winding core 411 and peripheral wall 412. A conductor 14 that goes around winding core 411 is provided inside circumferential groove 413.

[0062] In magnetic base 410 shown in Fig. 9, circumferential groove 413 is closed with magnetic lid 415, and conductor 14 is stored inside magnetic base 410. In contrast, magnetic base 420 shown in Fig. 10 is used with circumferential groove 413 open. Even when E-core type magnetic substrates 410, 420 are used, a strong bond is achieved by forming a base electrode 121 having the above-mentioned crystal plane structure on the outer surface of the magnetic substrates 410, 420 and joining the end 141 of the conductor 14.

[0063] 11 and 12 are diagrams showing two modified examples of the external electrode 12 having different structures. 11 and 12, the external electrode 12 also includes a base electrode 121, a conductive resin layer 123, and a plating layer 124. However, in the modification shown in FIG. 11, the second base electrode 121c extends over the side surface 103 more widely than the conductive resin layer 123. The conductive resin layer 123 is thicker than the other layers in the external electrode 12, and the smaller area of ​​the conductive resin layer 123 contributes to miniaturization of the coil component. Furthermore, the stress applied to the external electrode 12 is alleviated by the conductive resin layer 123 and is applied inward from the end of the base electrode 121, thereby preventing peeling of the external electrode from the magnetic bases 410, 420, which begins at the end of the base electrode 121.

[0064] 12, the conductive resin layer 123 extends over the side surface 103 more widely than the second base electrode 121c. Therefore, the stress generated in the external electrode 12 is alleviated by the extent of the conductive resin layer 123, and this is suitable for coil components in which the external electrode is thick or has a large area, for example.

[0065] FIG. 13 is a diagram showing a modified example in which the area of ​​the first base electrode 121b is narrow. 2 and 3, first base electrode 121b of base electrode 121 extends over the entire bottom surface 101 of magnetic base 11, whereas in a modified coil device 500 shown in Fig. 13, first base electrode 121b of base electrode 121 is provided only around end 141 of conductor 14 on bottom surface 101 of magnetic base 11. A second base electrode 121c extends around first base electrode 121b.

[0066] 13 , conductive resin layer 123 also covers the entire base electrode 121, and therefore when viewed in a direction perpendicular to bottom surface 101, conductive resin layer 123 surrounds joint portion 121a and first base electrode 121b over more than half the circumference of bottom surface 101. Therefore, conductive resin layer 123 can disperse stress acting in any direction, and the bond between base electrode 121 and end 141 of conductor 14 is protected. [Explanation of symbols]

[0067] 10 Circuit Board 11, 410, 420 magnetic substrate 12 External electrode 13 Exterior part 14 Conductors 121 Base electrode 121a Joint 121b 1st base electrode 121c 2nd base electrode 123 Conductive resin layer 124 plating layer 141 End of drawer 100, 300, 400, 500 coil parts 101 bottom 102 Top surface 103 Side 104 Front 105 Rear 200 boards 201 Land Club 211 (111) crystal face 212 Crystal faces other than (111) 214 Glass 215 void

Claims

1. a magnetic substrate; a conductor provided inside or on the surface of the magnetic substrate; an external electrode provided on the outer surface of the magnetic substrate, the external electrode including a base electrode to which an end of the conductor is joined at a joint; the junction extends over the same area as the end of the conductor, and the area ratio of the crystal planes thereof is such that the area ratio of crystal planes other than (111) is greater than the area ratio of the (111) crystal plane; Coil parts.

2. 2. The coil component according to claim 1, wherein the joint is sandwiched between the outer surface of the magnetic base and the end of the conductor.

3. the base electrode has a first base electrode around the junction, 2. The coil component according to claim 1, wherein the area ratio of the crystal planes of the first base electrode is such that the area ratio of the crystal planes other than the (111) plane is greater than the area ratio of the (111) crystal plane.

4. the base electrode has a second base electrode around the first base electrode, 2. The coil component according to claim 1, wherein the area ratio of the (111) crystal plane of the second base electrode is greater than the area ratio of crystal planes other than the (111) crystal plane.

5. The coil component according to claim 1 , wherein the external electrodes each have a conductive resin layer containing metal particles and resin on the outside of the joint.

6. The coil component according to claim 5 , wherein the conductive resin layer extends over an area wider than the area of ​​the joint.

7. The coil component according to claim 5 , wherein the conductive resin layer covers the end portion of the conductor.

8. The coil component according to claim 1 , wherein the external electrodes have a plating layer on their surfaces.

9. The coil component according to any one of claims 1 to 8, wherein whether or not the area ratio of the crystal planes other than the (111) is greater than the area ratio of the (111) crystal plane is determined based on cross-sectional observation of the joint using an electron backscattering method.

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