Coil component

Abstract

The present disclosure provides a coil component including a magnetic substrate and a conductor disposed inside the magnetic substrate or on a surface of the magnetic substrate. The coil component further includes an external electrode disposed on a surface of the magnetic base. The external electrode includes a base electrode having a bonding portion bonded to the conductor end portion. The joint portion expands to the same range as the conductor end portion. The area ratio of the (111) crystal plane in the bonding portion is smaller than the area ratio of the other crystal planes in the bonding portion.

Description

Technical Field

[0001] The present disclosure relates to coil components. Background Art

[0002] Due to environmental changes such as the increasing electrification of vehicles, the number of electronic components used in electronic products has increased, and the applications for which they are used are also expanding. This situation is common to many electronic components, and it also applies to winding-type coil components, in which a conductor (wire) is wound around a magnetic body. However, winding-type coil components have limitations such as assembly accuracy, and therefore their miniaturization is not as feasible as other types of electronic components. Winding-type coil components also need to be miniaturized, and it is also desirable to use thinner wires.

[0003] Electronic components are typically mounted on mounting boards using solder. As electronic components become smaller, stress caused by board deflection and temperature fluctuations can easily damage components and solder. Therefore, coil components require countermeasures to counteract these stresses.

[0004] For example, JP 2019-041075A discloses a coil component in which the adhesion strength of the lower surface electrode to the component body is lower than the adhesion strength of the end surface electrode to the component body. When an external force is applied to the external electrode, the lower surface electrode, which is part of the external electrode, moves relative to the component body, dissipating the stress. Summary of the Invention

[0005] If the configuration of JP 2019-041075A is used, a part of the external electrode will move due to stress. When a part of the external electrode moves, the conductor (wire) will be subjected to the stress of expansion and contraction. In particular, if the coil component uses a thin conductor (thin wire), the movement of the external electrode will increase the load applied to the conductor. Since the end of the conductor is engaged with the external electrode, if a large load is applied to the conductor, the connection between the conductor and the external electrode may be damaged by the load. Therefore, it is necessary to strengthen the connection between the external electrode and the conductor. If it is necessary to reduce the size of the coil component, it is also necessary to strengthen the connection between the external electrode and the conductor in the stacked coil component.

[0006] An object of the present disclosure is to enhance the connection between the external electrode and the conductor.

[0007] Additional or separate features and advantages of the present disclosure will be set forth in the following description, and in part will be apparent from the description, or may be learned through practice of the present disclosure. The purposes and other advantages of the present disclosure will be realized and obtained through the structures particularly pointed out in the specification and claims and the drawings.

[0008] To achieve these and other advantages and in accordance with the purposes of the present disclosure, as embodied and broadly described, in one aspect, the present disclosure provides a coil component comprising a magnetic substrate and a conductor disposed within the magnetic substrate or on the surface of the magnetic substrate. The coil component further comprises an external electrode disposed on the surface of the magnetic substrate. The external electrode comprises a base electrode having a joint that is joined to an end of the conductor. The joint extends to the same extent as the end of the conductor. The area ratio of the (111) crystal plane in the joint is less than the total area ratio of the other crystal planes in the joint.

[0009] The joint may be sandwiched between the surface of the magnetic base and the end of the conductor.

[0010] The substrate electrode may include a first substrate electrode surrounding the joint portion. An area ratio of a (111) crystal plane in the first substrate electrode may be smaller than a total area ratio of other crystal planes in the first substrate electrode.

[0011] The substrate electrode may include a second substrate electrode surrounding the first substrate electrode. The area ratio of the (111) crystal plane in the second substrate electrode may be greater than the total area ratio of other crystal planes in the second substrate electrode.

[0012] The external electrode may include a conductive resin layer located outside the bonding portion. The conductive resin layer may include metal particles and resin.

[0013] The conductive resin layer may extend to a range larger than that of the bonding portion.

[0014] The conductive resin layer may cover (extend beyond) the end portion of the conductor.

[0015] The external electrode may have a plating layer on its surface.

[0016] According to the present disclosure, the bonding between the external electrode and the conductor is enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A perspective view showing a coil component according to an embodiment of the present disclosure is shown.

[0018] Figure 2 Shown along Figure 1 Cross-sectional view taken along line II-II.

[0019] Figure 3 Shown along Figure 2 Cross-sectional view taken along line III-III.

[0020] Figure 4A Schematic diagram showing the microstructure of the joint surface of the joint portion.

[0021] Figure 4BIt is a schematic diagram for describing the structure of the joint portion before joining.

[0022] Figure 4C It is a schematic diagram for describing the structure of the joint portion after joining.

[0023] Figure 5 Shows drum core orientation and Figure 2 Longitudinal section through a first different variant.

[0024] Figure 6 Shown along Figure 5 A cross-sectional view taken along line VI-VI.

[0025] Figure 7 A longitudinal sectional view showing a second modification (laminated type) is shown.

[0026] Figure 8 Shown along Figure 7 A cross-sectional view taken along line VIII-VIII in FIG.

[0027] Figure 9 1 is a schematic diagram showing a first embodiment of an E-core type magnetic substrate.

[0028] Figure 10 1 is a schematic diagram showing a second embodiment of an E-core type magnetic substrate.

[0029] Figure 11 is a schematic diagram showing a first modification of the external electrode structure.

[0030] Figure 12 is a schematic diagram showing a second modification of the external electrode structure.

[0031] Figure 13 Schematic diagram showing a modified joint (narrower joint). DETAILED DESCRIPTION

[0032] The following embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The following embodiments are not intended to limit the present disclosure, and not all combinations of features described in the embodiments are required for the configuration of the present disclosure. Depending on the specifications and various conditions (usage conditions, usage environment, etc.) of the device to which the present disclosure is applied, the configuration of the embodiments may be modified or changed as necessary.

[0033] The technical scope of the present disclosure is defined by the claims and is not limited by the following embodiments. To make each configuration easier to understand, the drawings used in the following description may differ from the actual structure in scale and shape. Parts, elements, and assemblies shown in one drawing may be referenced in the description of other drawings.

[0034] <One embodiment of the coil component>

[0035] Figure 1 is a perspective view of a coil component 100 according to an embodiment of the present disclosure.

[0036] The coil component 100 is mounted on a substrate (board) 200. The substrate 200 can be referred to as a mounting board. The substrate 200 is provided with two pad portions 201. The coil component 100 has two external electrodes 12. The coil component 100 is mounted on the substrate 200 by respectively bonding the two external electrodes 12 to the two pad portions 201 with solder.

[0037] Reference numeral 10 denotes a circuit device (circuit board) including a coil component 100 and a substrate 200 on which the coil component 100 is mounted. The circuit device 10 is used in various electronic devices. The electronic device including the circuit device 10 is, for example, an electrical component of an automobile, a server, a tablet computer, or other electronic devices.

[0038] The coil component 100 may be an inductor, a transformer, a filter, a reactor, or various other coil components. The coil component 100 may be a coupled inductor, a choke, or 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 herein.

[0039] In this specification, unless the context requires otherwise, directions are described in terms of Figure 1 The L-axis, W-axis, and H-axis directions are used as reference. The L-axis direction is the length direction. The W-axis direction is the width direction. The H-axis direction is the height direction.

[0040] The coil component 100 has, for example, a rectangular parallelepiped shape. The coil component 100 has outer surfaces at both ends (right and left surfaces) in the length direction L, outer surfaces at both ends (upper and lower surfaces) in the height direction H, and outer surfaces at both ends (front and rear surfaces) in the width direction W. The rectangular parallelepiped shape of the coil component 100 has eight corners and twelve edges.

[0041] The dimensions of each side of the rectangular parallelepiped coil component 100 are such that the dimension in the length direction L is, for example, in the range of 1.0 mm to 4.5 mm, the dimension in the width direction W is, for example, in the range of 0.5 mm to 3.2 mm, and the dimension in the height direction H is, for example, in the range of 0.5 mm to 1.0 mm. The dimension of the coil component 100 in the height direction H is smaller than the dimension in the length direction L. The dimension of the coil component 100 in the height direction H is smaller than the dimension in the width direction W.

[0042] Each outer surface of the coil component 100 may be a flat plane, a curved surface, or a surface having a step (convex / concave) at a portion thereof. The eight corners and twelve ridges of the coil component 100 may have rounded corners.

[0043] In this specification, even if a portion of the outer surface of the coil component 100 is curved or has steps, or if the corners or edges of the coil component 100 have rounded shapes, the coil component 100 having these shapes may be referred to as a rectangular parallelepiped component. In other words, in this specification, the term "rectangular parallelepiped" or "rectangular parallelepiped shape" does not refer to a "rectangular parallelepiped" in the strict mathematical sense.

[0044] <Structure of coil component>

[0045] Figure 2 It is along Figure 1 Cross-sectional view taken along line II-II. Figure 3 It is along Figure 2 The cross-sectional view taken along line III-III in FIG. Figures 1 to 3 The coil component 100 is described.

[0046] The coil component 100 includes, for example, a magnetic base (element body) 11, an external electrode 12, and a conductor 14 inside the magnetic base 11. The coil component may further include an exterior portion 13.

[0047] The magnetic base 11 is called a drum core and includes two flanges 111 and a winding core 112. The magnetic base 11 has side surfaces (left and right surfaces) 103 at both ends in the length direction L. The magnetic base 11 has a lower surface 101 at one end in the height direction H of the flange 111 and an upper surface 102 at the other end in the height direction H. The magnetic base 11 has a front surface 104 at one end in the width direction W of the flange 111 and a rear surface 105 at the other end in the width direction W. The lower surface 101 is a mounting surface that will face the substrate 200 when the coil component 100 is mounted on the substrate 200.

[0048] Upper surface 102 is the surface opposite lower surface 101, i.e., upper surface 102 faces upward, while lower surface 101 faces downward. Upper surface 102 is adjacent to side surface 103, front surface 104, and rear surface 105. Similarly, lower surface 101 is adjacent to side surface 103, front surface 104, and rear surface 105. If two surfaces are adjacent to each other, they are in a positional relationship where no other surface is interposed between the two adjacent surfaces. An edge is defined by two adjacent surfaces. In the illustrated embodiment, the adjacent surfaces are orthogonal to each other. Upper surface 102 can be referred to as top surface 102.

[0049] The magnetic substrate 11 may include a magnetic material or a non-magnetic material. The magnetic material used for the magnetic substrate 11 may be ferrite or a soft magnetic metal. The non-magnetic material used for the magnetic substrate 11 may be alumina or glass. It should be noted that the magnetic material used for the magnetic substrate 11 may be various crystalline or amorphous metallic magnetic materials, or a combination of crystalline and amorphous materials.

[0050] Examples of crystalline metal magnetic materials that can be used as the magnetic material for the magnetic base 11 include materials containing 50 wt% or more or 85 wt% or more of Fe as a main component and one or more elements selected from the group consisting of Si, Al, Cr, Ni, Ti, and Zr. Examples of amorphous metal magnetic materials that can be used as the magnetic material for the magnetic base 11 include materials containing B or C in addition to any of Si, Al, Cr, Ni, and Zr.

[0051] The magnetic material used for the magnetic base 11 can be pure iron made of Fe and inevitable impurities. Alternatively, the magnetic material used for the magnetic base 11 can also be a material obtained by combining pure iron made of Fe and inevitable impurities and a metallic magnetic material (which is a crystalline or amorphous alloy). The material of the magnetic base 11 is not limited to the materials explicitly described in this specification. In other words, the material of the magnetic base 11 can be any suitable material known as a base material for a coil component.

[0052] The magnetic matrix 11 can be made by the following method. First, the powder of the magnetic material or non-magnetic material described above is mixed with a lubricant to prepare a mixed material. Then, the mixed material is placed in the cavity of a mold and press-molded to form a green body. Subsequently, the green body is heat-treated to produce the magnetic matrix 11. The green body can be shaped by grinding before the heat treatment. The magnetic matrix 11 can be molded by a molding method.

[0053] Alternatively, the magnetic substrate 11 can be manufactured by mixing powders of the aforementioned magnetic or non-magnetic materials with resin, glass, or an insulating oxide (e.g., Ni-Zn ferrite or silica), forming the mixed material by lamination, etc., and heat-treating the mixed material. The heat treatment applied to the magnetic substrate 11 can be determined based on the raw materials used. For example, the heat treatment may include heat curing at a temperature below 200°C or sintering at a temperature above 600°C (or above 1100°C).

[0054] The magnetic base 11 is preferably not affected by the heat generated during the formation of the external electrodes 12. Specifically, the magnetic base 11 preferably contains a small amount of resin or the like, which is susceptible to the heat generated during the formation of the external electrodes. The proportion of the resin is preferably less than 1% of the volume of the magnetic base 11, for example.

[0055] The conductor 14 is formed by winding a metal wire around the core 112 of the magnetic base 11. The metal conductor has an insulating film on its surface. The main body of the conductor 14 is a winding portion having a wire wound around the core 112. The wire of the conductor 14 is made of a metal material with excellent electrical conductivity. The metal material used for the conductor 14 is, for example, one or more metals of Cu, Ag and Al, or an alloy of these metals. The conductor 14 has low resistance. Specifically, the filling rate of the metal material in the conductor 14 is, for example, 90% or more (or 98% or more). The insulating material used as the coating film of the conductor 14 can be a general material such as polyamide-imide, polyamide, polyimide or polyurethane.

[0056] The cross-sectional shape of the wire of the conductor 14 is, for example, circular, rectangular, or elliptical. For reasons such as low resistance and processing diversity (processing different uses), it is preferred to use a general-purpose wire as the wire of the conductor 14. The number of wire turns in the winding portion of the conductor 14 is, for example, between 1.5 turns and 10.5 turns. The overall shape of the winding can be a flat shape or a spiral shape. It should be noted that the winding portion may have two groups of windings, which face each other to form a single aggregate. Figure 2 and Figure 3 , a so-called vertical winding is shown, in which the wire is wound approximately parallel to the side surface 103 of the magnetic base 11 .

[0057] The conductor 14 has a lead portion for electrical conduction with the outside (the end portion 141 of the lead portion is only Figure 2 ). The end portions 141 of the lead portions are respectively connected to the base electrodes 121 (to be described later) of the external electrodes 12. The end portions 141 of the conductors 14 are bonded to the base electrodes 121, so that the external electrodes 12 and the conductors 14 are electrically connected.

[0058] The bonding between each base electrode 121 and the associated end portion 141 of the conductor 14 is achieved by, for example, placing the end portion 141 on the base electrode 121 and applying heat to the base electrode 121 and the end portion 141. At least a portion of the base electrode 121 and a portion of the associated end portion 141 are melted by the applied heat, so that the two metals (base electrode 121 and end portion 141) are bonded to each other.

[0059] The heating during the above-mentioned joining process is performed at a temperature lower than the temperature at which the two metals (base electrode 121 and end portion 141) are completely melted, or the heating time is limited to a time shorter than the time required for complete melting. The joining process is performed at a temperature lower than the sintering temperature of base electrode 121. The sintering temperature will be described below. If the heating time is limited, the heating temperature can be a temperature close to the complete melting temperature. For example, when measured in Kelvin temperature, the heating temperature (joining temperature) of conductor 14 and base electrode 121 is between 0.5 and 0.8 times the melting point of the metal of conductor 14.

[0060] The heating process in the above-mentioned bonding process includes, for example, laser irradiation of the end portion 141 of the conductor 14 or pressurized heating using a heater chip. When the cross-sectional area of ​​the conductor 14 is greater than 0.008 mm 2 In the case of the heating process, a laser is used. On the other hand, when the cross-sectional area of ​​the conductor 14 is equal to or less than 0.008 mm 2 In the case of a heater chip, the conductor 14 is applied. The choice of heating process is also affected by the heat conduction during bonding. Specifically, when the volume of the coil component 100 is greater than 50 mm 3 In the case of using a laser, the volume of the coil component 100 is less than or equal to 50 mm 3 Use heater chip in this case.

[0061] The outer covering 13 is made of a resin material containing ceramic particles and metal particles and surrounds the outer periphery of the winding portion of the conductor 14 to protect the conductor 14. The outer covering 13 is formed by applying a resin material paste to the outer periphery of the winding portion of the conductor 14, for example.

[0062] The coil component 100 includes, for example, two external electrodes 12 . Figures 1 to 3 The external electrodes 12 shown can be referred to as double-sided electrodes because each of the external electrodes 12 is formed on both surfaces (i.e., the lower surface 101 and the side surface 103) of the magnetic base 11. It should be noted that each external electrode 12 can be formed only on the lower surface 101, in which case such external electrodes 12 are referred to as single-sided electrodes.

[0063] It should be noted that the terms "disposed on a surface" or "formed on a surface" refer to being disposed / formed in a portion (or region) that can be seen when observing the surface. When observed in a direction perpendicular to the surface, the target (or component) may extend outward from the surface, or may extend downward in a direction perpendicular to the surface.

[0064] <Structure of External Electrodes>

[0065] Each external electrode 12 includes, for example, a base electrode 121, a conductive resin layer 123, and a plating layer 124. The base electrode 121 includes, for example, a bonding portion 121a that bonds with the end portion 141 of the lead portion of the conductor 14, a first base electrode 121b surrounding the bonding portion 121a, and a second base electrode 121c. It should be noted that the base electrode 121 may not include the second base electrode 121c. When the external electrode 12 includes the conductive resin layer 123, the conductive resin layer 123 is provided outside the base electrode 121. When the external electrode 12 includes the plating layer 124, the plating layer 124 is provided outside the base electrode 121 and the conductive resin layer 123.

[0066] Each substrate electrode 121 is made of any one of Cu, Ag and Pd and is sintered. Alternatively, the substrate electrode 121 can be made of an alloy containing any one of Cu, Ag and Pd, and can also contain a glass material. The joint 121a is a region sandwiched between the outer surface of the magnetic base 11 and the end 141 of the conductor 14. When the crystal planes in the joint 121a are divided into (111) crystal planes and other crystal planes, the joint 121a includes "other crystal planes" in addition to the (111) crystal planes. In the joint 121a, when the presence of the (111) crystal plane and the presence of the "other crystal planes" are compared from the perspective of area ratio, the area ratio of the "other crystal planes" (crystal planes other than the (111) crystal plane) is greater than the area ratio of the (111) crystal plane.

[0067] Figure 4A The microstructure of the joint portion 121 a is schematically shown.

[0068] The joint portion 121a includes a mixture of crystal planes (crystal planes) 211 and 212 of, for example, Ag (conductive material), glass 214 (insulator), and voids 215. The glass 214 is mostly present between the base electrode 121 and the outer surface of the magnetic base 11, and provides strength at the interface between the base electrode 121 and the outer surface of the magnetic base 11.

[0069] The Ag crystal planes 211 and 212 of the joint portion 121a are, for example, the (111) crystal plane 211 and the other crystal planes 212. The "other crystal planes" 212 include the (100) crystal plane and the (110) crystal plane. In the joint portion 121a, the area ratio of the crystal plane 211 (the (111) crystal plane) is smaller than the area ratio of the crystal planes 212 (the (100) crystal plane and the (110) crystal plane). The area ratio of the crystal planes 211 and 212 can be obtained from a 2000-fold cross-sectional view of the joint portion 121a using, for example, an electron beam backscattering method, or can be obtained from the length ratio.

[0070] Similar to the junction portion 121a, in the first base electrode 121b, the area ratio of the (111) crystal plane 211 is smaller than the area ratios of the other crystal planes 212 (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.

[0071] Here, we will refer to Figure 4B and Figure 4C The structure of the bonding portion 121 a (base electrode 121 ) before bonding and the structure of the bonding portion 121 a (base electrode 121 ) after bonding are described. Figure 4B The structure of the bonding portion 121 a (base electrode 121 ) before bonding is shown. Figure 4C The structure of the bonding portion 121 a (base electrode 121 ) after bonding is shown.

[0072] The base electrode 121 undergoes a sintering process, so that the powder of the starting materials (Cu, Ag, Pd) undergoes solid phase sintering. As a result, Figure 4B As shown, the substrate electrode 121 has a stepped structure with outlines. The (111) crystal plane 211 is parallel to the lower surface 101 of the substrate 11. Other crystal planes 212 are exposed in the form of stepped surfaces and have a different plane orientation from the (111) crystal plane 211.

[0073] In from Figure 4B During the bonding process of bonding the end portion 141 of the conductor 14 to the base electrode 121 (bonding the end portion 141 to the bonding portion 121a), the step structure (three-dimensional structure) of the base electrode 121 undergoes plastic deformation. As a result of the plastic deformation, Figure 4C As shown, the (111) crystal plane 211 and the other crystal planes 212 have the same plane orientation. This provides an interface between the joint portion 121a and the end portion 141.

[0074] The base electrode 121 of the external electrode 12 is formed by applying a slurry of a metal material containing metal particles to the outer surface of the magnetic base 11 and sintering the metal material. The metal material can be a combination of metal particles of different shapes or a combination of metal particles of different sizes. In terms of shape, the combination includes, for example, a spherical shape combined with a plate shape and / or a scale shape. In terms of size, the combination includes, for example, a smaller spherical shape combined with a plate shape with a large size in the longest direction and / or a scale shape with a large size in the longest direction. The sintering temperature of the joint 121a is, for example, between 0.6 times and 0.85 times the melting point of the metal of the joint 121a when measured in Kelvin temperature.

[0075] The metal material is sintered at a temperature such that, at least in the joint portion 121a, all metal grains are not sintered when sintering is complete. For example, smaller metal particles in the metal material readily melt and diffuse into surrounding metal particles, thereby reducing voids and achieving densification. However, larger metal particles rarely melt and sintering is performed at a temperature that is not conducive to densification. Furthermore, plate-shaped, flaky, and spherical particles can be combined, and depending on the shape of the diffusion particles involved, some particles with a larger specific surface area may diffuse and bond to surrounding metal particles.

[0076] Thus, the densification of the metal material in the joint portion 121a is incomplete or uneven. Therefore, in this embodiment, the crystal planes 212 are formed more frequently than the (111) crystal planes 211. As described below, the joint strength at the joint surface between the base electrode 121 and the end portion 141 of the conductor 14 is enhanced. For example, the filling rate of the metal material in the base electrode 121 is between 60% and 85%.

[0077] Since the metal at the (111) crystal plane 211 is dense and stable, metal diffusion between the conductor 14 and the joint portion 121a is unlikely to occur during bonding. On the other hand, the crystals of the (100) crystal plane 212 and the (110) crystal plane 212 are not in a stable state, resulting in the possibility of diffusion, and the (100) crystal plane 212 and the (110) crystal plane 212 are able to receive (accept) the metal that has diffused and moved toward them.

[0078] Therefore, the area ratio of the crystal plane 212 (which is unstable as a metal) is greater than the area ratio of the (111) crystal plane 211 (which is stable as a metal). As a result, metal diffusion is likely to occur between the joint 121a and the conductor 14, and metal movement is likely to occur during metal diffusion. As a result, the joint at this interface is strong. For this reason, even when using a thicker wire (for example, the thickness restriction of the wire of the conductor 14 is relaxed and the area of ​​the joint surface becomes larger), metal diffusion may occur in the entire joint 121a, and the joint strength is enhanced.

[0079] Return Reference Figures 1 to 3 The conductive resin layer 123 of each external electrode 12 contains a resin and a metal filler. The resin of the conductive resin layer 123 is, for example, a thermosetting resin, and the metal filler of the conductive resin layer 123 contains, for example, a metal having the same composition as that of the base electrode 121. Examples of the metal filler include Ag, Pd, Cu, Al, Ni, Sn, and alloys thereof, and the preferred metal filler is Ag or Cu.

[0080] It should be noted that a single metal filler may be used alone or in combination of two or more metal fillers. If two or more metal fillers are used, shapes such as spherical, prolate, flat, and rod-shaped may be used in combination. In particular, a combination of rod-shaped and spherical shapes or a combination of rod-shaped, spherical, and flat shapes is preferred. For example, in order to reduce resistance, the conductive resin layer 123 contains more flat metal fillers than other metal fillers. The conductive resin layer 123 contains a resin (e.g., an epoxy resin, a phenolic resin, or an acrylic resin). The resin content in the conductive resin layer 123 is between 30 vol% and 70 vol%.

[0081] End 141 of conductor 14 is sandwiched between conductive resin layer 123 and joint 121a. When conductive resin layer 123 is provided within external electrode 12, it reduces stress caused by strain on substrate 200 and the like. The stress-relieving effect provided by conductive resin layer 123 extends not only to the joint between base electrode 121 and end 141 but also to the lead-out portion of conductor 14 through end 141. Consequently, even when conductor 14 is made of a thin wire, stress-induced problems are suppressed or prevented.

[0082] The conductive resin layer 123 covers the outer side (lower surface) of the end portion 141 of the conductor 14. Therefore, the conductive resin layer 123 holds the end portion 141 of the conductor 14 and suppresses stress on the end portion 141 of the conductor 14. Figure 3 As shown, the conductive resin layer 123 is in contact with the first base electrode 121b. Therefore, the conductive resin layer 123 surrounds the end portion 141 that is bonded to the bonding portion 121a.

[0083] The conductive resin layer 123 is provided in a range wider than the bonding portion 121a and covers the entire base electrode 121. Therefore, a stress relaxation effect can be obtained regardless of the direction of stress.

[0084] The plating layer 124 can be provided on the surface of the external electrode 12 and can cover the entire resin layer 123. The plating layer 124 is made of a metal material having excellent conductive properties. For example, Cu or Ag can be used as the metal material of the plating layer 124. Alternatively, Ni, Pd or Sn can be used as the metal material of the plating layer 124. The plating layer 124 can be formed into a multilayer structure. For example, a plurality of layers mainly composed of the above-mentioned metal materials can form a multilayer structure, or a plurality of partially alloyed layers can form a multilayer structure. The plating layer 124 is provided to improve the welding strength with the external electrode 12. It should be noted that the plating layer 124 can be replaced by a solder layer to facilitate welding.

[0085] <Variation method>

[0086] Hereinafter, a description will be given of a modification of the above-described coil component 100. The following description will focus on differences from the above-described coil component 100, and repeated description of elements similar to those already described will be omitted.

[0087] Figure 5 and Figure 6 A first variation is shown (coil component 300) in which the drum core is oriented with respect to Figure 2 and Figure 3 different. Figure 5 A longitudinal cross-sectional view taken parallel to the H-axis and the L-axis is shown. Figure 6 Shown along Figure 5 A cross-sectional view taken along line VI-VI.

[0088] Figure 5 and Figure 6 The orientation of the magnetic substrate 11 in the coil component 300 of the illustrated variant is different from Figure 2 and Figure 3 Specifically, one of the flanges 111 is located on the side of the lower surface 101 serving as the mounting surface. The other flange 111 of the magnetic base 11 is located on the side of the upper surface 102. The winding core 112 of the magnetic base 11 extends in the height direction H, and the conductor 14 has a so-called horizontal winding in which the wire is wound approximately parallel to the lower surface 101 and the upper surface 102. The coil component 300 may not include the outer casing 13, as shown in FIG. Figure 5 shown.

[0089] exist Figure 5 and Figure 6 In the illustrated modification, each external electrode 12 includes a base electrode 121, a conductive resin layer 123, and a plating layer 124, and an end portion 141 of a lead portion of a conductor 14 is joined to a joining portion 121a. Figure 5 and Figure 6 In the illustrated variation, the conductor 14 has a thicker wire, resulting in a larger bonding surface area. However, because the external electrode 12 includes the bonding portion 121a having the aforementioned crystal plane structure, the bonding strength is high. In the illustrated variation, the base electrode 121 has a first base electrode 121b disposed around the bonding portion 121a, and a second base electrode 121c separated from the bonding portion 121a.

[0090] The first substrate electrode 121b has the same crystal plane structure as the joint portion 121a, and the second substrate electrode 121c has a different crystal plane structure from the joint portion 121a. For example, in the second substrate electrode 121c, the area ratio of the (111) crystal plane is greater than the area ratio of the "other crystal planes." Since the external electrode 12 includes the substrate electrode 121 having the second substrate electrode 121c, the external electrode 12 can have the desired strength and resistance.

[0091] Figure 7 and Figure 8 A second modification (coil component 400) is shown. The coil component 400 is a laminated type. Figure 7 A longitudinal cross-sectional view taken parallel to the H-axis and the L-axis is shown. Figure 8 Shown along Figure 7 A cross-sectional view taken along line VIII-VIII in FIG.

[0092] Figure 7 and Figure 8 The laminated coil component 400 is shown. In the laminated coil component 400, the conductor 14 is provided inside the magnetic base 11, and the end portion 141 of the lead portion is exposed on the lower surface 101 of the magnetic base 11.

[0093] Figure 7 and Figure 8 The coil component 400 shown has two external electrodes 12 , each of which is referred to as a five-sided electrode. The five-sided electrode (external electrode) 12 extends from one side surface 103 to a lower surface 101 , an upper surface 102 , a front surface 104 , and a rear surface 105 .

[0094] External electrode 12 includes a base electrode 121, a conductive resin layer 123, and a plating layer 124. Base electrode 121 has a first base electrode 121b surrounding a joint 121a. In laminated coil component 400, the metal material of base electrode 121 is applied to the exposed portion of end 141 of the lead portion and sintered. As a result, base electrode 121 is formed, and end 141 is bonded to joint 121a.

[0095] exist Figure 7 and Figure 8 In the coil component 400 shown, the joint 121a and the first substrate electrode 121b are formed only in the area overlapping with the end 141, and the rest of the substrate electrode 121 is the second substrate electrode 121c. When the range of forming the joint 121a and the first substrate electrode 121b is limited (restricted) and the area of ​​the second substrate electrode 121c in the substrate electrode 121 is large, the substrate electrode 121 as a whole has high strength and low resistance. When the range of setting the second substrate electrode 121c is not limited to the same surface as the first substrate electrode 121b, but is set on two surfaces, higher strength can be obtained. That is, the coil component 400 manufactured in this way is connected to the conductor 14 through the joint 121a, and obtains strength as an external electrode through the second substrate electrode 121c.

[0096] Figure 9 A third variant is shown (base 410 ), Figure 10A fourth modification (substrate 420 ) is shown. In each of the third and fourth modifications, the magnetic substrate 410 / 420 is an E-core type. The magnetic substrate 410 is different from the magnetic substrate 420 .

[0097] For example, Figure 9 and Figure 10 Each of the magnetic substrates 410, 420 shown may be substituted for Figures 1 to 3 The magnetic substrate 11 shown uses an E-core type magnetic substrate 410 / 420 having a core 411 and a peripheral wall 412 surrounding the core 411. An annular groove 413 is formed between the core 411 and the peripheral wall 412, extending around the core 411. The conductor 14 wound around the core 411 is disposed within the annular groove 413.

[0098] exist Figure 9 In the magnetic base 410 shown, the annular groove 413 is closed by a cover 415. The cover 415 is made of a magnetic material. The conductor 14 is accommodated in the interior of the magnetic base 410. On the other hand, Figure 10 The magnetic base 420 is shown without a cover. The magnetic base 420 is used in a state where the annular groove 413 is open.

[0099] Even in the case of using the E-core type magnetic base 410 / 420 , the base electrode 121 having the above-described crystal plane structure is formed on the outer surface of the magnetic base 410 / 420 , and the end portions 141 of the conductors 14 are joined to achieve strong joining.

[0100] Figure 11 A fifth variant is shown, Figure 12 The structure of the external electrode 12 in the fifth / sixth embodiment is different from that in the sixth embodiment. Figure 2 .

[0101] exist Figure 11 and Figure 12 In each of the variations shown, each external electrode 12 includes a base electrode 121, a conductive resin layer 123, and a plating layer 124. However, in Figure 11 In the illustrated variation, second base electrode 121c extends further (extends higher) than conductive resin layer 123 on side surface 103. Conductive resin layer 123 is thicker than the other layers in external electrode 12. Therefore, if the extended area of ​​conductive resin layer 123 is small, it contributes to the miniaturization of the coil component. Since the stress applied to external electrode 12 is mitigated by conductive resin layer 123 and applied inward from the end of base electrode 121, it is possible to prevent external electrode 12 from peeling off from magnetic substrate 410 / 420 at the end of base electrode 121.

[0102] On the other hand, Figure 12In the illustrated modification, the conductive resin layer 123 extends further (extends higher) than the second base electrode 121c on the side surface 103. Therefore, the stress generated in the external electrode 12 is relieved by the conductive resin layer 123. Accordingly, Figure 12 The modified manner is suitable for coil components having, for example, thicker outer electrodes 12 or outer electrodes 12 with larger areas.

[0103] Figure 13 A seventh modification (coil component 500 ) is shown in which the area of ​​each first substrate electrode 121 b is smaller.

[0104] Figure 3 The first substrate electrode 121b of each substrate electrode 121 shown in FIG. 1 extends over the entire lower surface 101 of the magnetic substrate 11, while Figure 13 In the modified coil component 500 shown in FIG, the first base electrode 121b of the base electrode 121 extends only around the end portion 141 of the conductor 14 on the lower surface 101 of the magnetic base 11. The second base electrode 121c extends around the first base electrode 121b.

[0105] exist Figure 13 In the illustrated variation, two conductive resin layers 123 each entirely cover the two base electrodes 121. Thus, when viewed perpendicularly to the lower surface 101, each conductive resin layer 123 surrounds the joint 121a and the first base electrode 121b over more than half the circumference of the lower surface 101. Thus, the conductive resin layers 123 can disperse stress applied in any direction and protect the joint between the base electrode 121 and the end 141 of the conductor 14.

[0106] It will be apparent to those skilled in the art that various modifications and variations may be made to the present disclosure without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is intended to cover modifications and variations that fall within the scope of the appended claims and their equivalents. In particular, it is expressly contemplated that any two or more of the above-described embodiments and any or all of their variations may be combined and considered within the scope of the present disclosure.

Claims

1. A coil component, comprising: Magnetic substrate; a conductor disposed inside the magnetic substrate or on the surface of the magnetic substrate; as well as An external electrode is provided on the surface of the magnetic substrate; wherein The external electrode includes a base electrode having a joint portion to be joined to an end portion of the conductor, The joint portion extends to the same extent as the end of the conductor, and The area ratio of the (111) crystal plane in the joint portion is smaller than the area ratios of other crystal planes in the joint portion.

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

3. The coil component according to claim 1, wherein The substrate electrode includes a first substrate electrode surrounding the joint portion, and an area ratio of a (111) crystal plane in the first substrate electrode is smaller than an area ratio of other crystal planes in the first substrate electrode. The coil component according to claim 3 , wherein: The substrate electrode has a second substrate electrode surrounding the first substrate electrode, and an area ratio of a (111) crystal plane in the second substrate electrode is greater than an area ratio of other crystal planes in the second substrate electrode. The coil component according to claim 1 , wherein The external electrode includes a conductive resin layer located outside the bonding portion, and the conductive resin layer contains metal particles and a resin. The coil component according to claim 5 , wherein The conductive resin layer extends to a range larger than that of the joining portion.

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 A plating layer is provided on the surface of the external electrode.

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