Coil components, circuit boards, electronic devices, and methods for manufacturing coil components

Abstract

To suppress the thickness of an external electrode in which solder is used.SOLUTION: A coil component according to an embodiment includes a base, a conductor provided on at least one of the inside and the surface of the base, and an external electrode that is provided on the first surface of the base and extending in the first direction, in which the width in the second direction perpendicular to the first direction becomes maximum at multiple locations in the first direction, and the width in the second direction is minimal at a location sandwiched between two maximal locations adjacent to each other in the first direction, and at least the surface of which is made of solder and that is connected to the conductor.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a coil component, a circuit board, an electronic device, and a method for manufacturing a coil component.

Background Art

[0002] Electronic devices such as communication devices and in-vehicle electrical equipment are becoming more and more high-performance, and accordingly, electronic components are required to have high performance and be miniaturized. In addition, electronic devices including portable devices are required to reduce power loss. Therefore, for coil components, those with low resistance are required.

[0003] In coil components, low resistance is achieved by using thick conductive wires. As a connection form between a thick conductive wire and an external electrode, a form in which at least a part of the end of the conductive wire is embedded in the external electrode has been proposed. Further, Patent Document 1 proposes a form in which the end of a flattened conductive wire is overlapped with an external electrode and welded as a connection form between the conductive wire and the external electrode.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the end of a conductive wire is embedded in an external electrode, a structure in which the external electrode is formed by solder and the end of the conductive wire is connected to the external electrode by the solder can be considered. However, when the external electrode is formed by solder, the solder has a thickness due to the surface tension during melting, so the external electrode becomes thick.

[0006] Therefore, an object of the present invention is to suppress the thickness of an external electrode using solder. <00********034>[Means for solving the problem]

[0007] To solve the above problems, a coil component according to one aspect of the present invention comprises a base body, a conductor provided on at least one of the interior and surface of the base body, and an external electrode provided on the first surface of the base body and extending in a first direction, wherein the width in a second direction perpendicular to the first direction is maximized at multiple locations in the first direction, and the width in the second direction is minimized at a location sandwiched between two adjacent maximum locations in the first direction, and at least the surface of the external electrode is made of solder and is connected to the conductor.

[0008] Furthermore, according to one aspect of the present invention, the width of the external electrode is narrower in the central portion in the first direction than in the portions on either side of the central portion. Furthermore, according to one aspect of the present invention, the coil component comprises at least one pair of external electrodes, the pair of external electrodes are spaced apart from each other in the second direction, and the thickness of each electrode in the third direction perpendicular to the first direction and the second direction is such that at the point of minimum thickness, it is thinner than at the point of maximum thickness adjacent to the point of minimum thickness.

[0009] Furthermore, according to one aspect of the present invention, the coil component comprises at least one pair of external electrodes, wherein the pair of external electrodes are spaced apart from each other in the second direction, each extending in the first direction, and the sides that are located on the outside of each other in the second direction extend linearly in the first direction. Furthermore, according to one aspect of the present invention, the base has a groove that is recessed from the first surface toward the interior of the base and extends in the first direction, and the external electrode has a maximum portion that covers a part of the groove in the first direction.

[0010] Furthermore, according to one aspect of the present invention, the coil component comprises an underlayment extending in the first direction, the width in the second direction being maximized at multiple locations in the first direction, and the width in the second direction being minimized at a location sandwiched between two adjacent maximum locations in the first direction, and a solder layer formed on the underlayment. Furthermore, according to one embodiment of the present invention, the conductor is connected to the solder at the maximum portion of the external electrode.

[0011] Furthermore, a circuit board according to one aspect of the present invention comprises either the above-mentioned coil component or a substrate on which the above-mentioned coil component is mounted.

[0012] Furthermore, an electronic device according to one aspect of the present invention includes the above-mentioned circuit board. Furthermore, a method for manufacturing a coil component according to one aspect of the present invention is a method for manufacturing any of the above-mentioned coil components, comprising the steps of: forming a base layer on the first surface that extends in the first direction, the width in the second direction being maximized at multiple locations in the first direction, and the width in the second direction being minimized at a location sandwiched between two adjacent maximum locations in the first direction; and forming a solder layer on the base layer. [Effects of the Invention]

[0013] According to the present invention, the thickness of the external electrode using solder can be suppressed. [Brief explanation of the drawing]

[0014] [Figure 1] This is a perspective view showing a coil component related to one embodiment of the present invention. [Figure 2] These are cross-sectional and side views of the coil component. [Figure 3] This is a perspective view showing a modified coil component. [Figure 4] These are cross-sectional and side views showing modified examples of coil components. [Figure 5] This diagram schematically shows the shape of the external electrode. [Figure 6]It is an enlarged cross-sectional view showing the structure of the external electrode. [Figure 7] It is a diagram showing the preparation stage in the procedure for forming the external electrode. [Figure 8] It is a diagram showing the first layer formation stage in the procedure for forming the external electrode. [Figure 9] It is a diagram showing the second layer formation stage in the procedure for forming the external electrode. [Figure 10] It is a diagram showing the coil component of the comparative example. [Figure 11] It is a diagram showing the external electrode in the coil component of the second embodiment. [Figure 12] It is a diagram showing the external electrode in the coil component of the third embodiment. [Figure 13] It is a diagram showing the external electrode in the coil component of the fourth embodiment. [Figure 14] It is a diagram showing the external electrode in the coil component of the fifth embodiment. [Figure 15] It is a diagram showing the external electrode in the coil component of the sixth embodiment.

Mode for Carrying Out the Invention

[0015] 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 combinations of the features described in the embodiments are essential to the configuration of the present invention. The configuration of the embodiments can be appropriately modified or changed according to the specifications of the device to which the present invention is applied and various conditions (usage conditions, usage environment, etc.).

[0016] The technical scope of the present invention is defined by the claims and is not limited by the following individual embodiments. The drawings used in the following description may differ in actual structure, scale, shape, etc. for the purpose of making each configuration easier to understand. Regarding the components shown in the previously described drawings, reference may be made as appropriate in the description of the subsequent drawings.

[0017] <Structure of the Coil Component> Figure 1 is a perspective view showing a coil component according to one embodiment of the present invention, and Figure 2 is a cross-sectional view and a side view of the coil component. Figure 2 shows a cross-section and a side view along line AA shown in Figure 1. The coil component 1 is mounted on the substrate 2a. The substrate 2a is provided with, for example, two land portions 3. The coil component 1 is mounted on the substrate 2a by joining each of the two external electrodes 12 to the corresponding land portion 3 on the substrate 2a with mounting solder. A circuit board 2 according to one embodiment of the present invention comprises the coil component 1 and the substrate 2a on which the coil component 1 is mounted. The circuit board 2 can be installed in various electronic devices. Examples of electronic devices equipped with the circuit board 2 include smartphones, tablets, game consoles, automotive electronics, servers, board computers, and various other electronic devices.

[0018] Coil component 1 may be an inductor, transformer, filter, reactor, or any other type of coil component. Coil component 1 may also be a coupled inductor, choke coil, or any other type of magnetically coupled coil component. Coil component 1 may be, for example, an inductor used in a DC / DC converter. The applications of coil component 1 are not limited to those expressed herein.

[0019] In this specification, unless otherwise understood in context, directions are described using the "L-axis," "W-axis," and "H-axis" directions of Figure 1 as reference, and are referred to as the "length," "width," and "height" directions, respectively. The "height" direction may also be referred to as the "thickness" direction.

[0020] The coil component 1 has a first main surface 1a (top surface 1a) and a second main surface 1b (bottom surface 1b) at both ends in the height direction. Both the top surface 1a and the bottom surface 1b of the coil component 1 may be flat planes or curved surfaces. In one embodiment of the present invention, the coil component 1 comprises a base body 11, an external electrode 12, an outer casing 13, and a conductor 14. Here, the base body 11 is referred to as a drum core, on which the conductor is wound around its surface. The coil component may also be provided without the outer casing 13. Alternatively, the base 11 may cover the entire conductor 14, with the conductor 14 positioned inside it (not shown).

[0021] The substrate 11 is made of a magnetic material or a non-magnetic material. For example, ferrite and soft magnetic alloy materials can be used as magnetic materials for the substrate 11. Alumina and glass can be used as non-magnetic materials for the substrate 11. The magnetic material for the substrate 11 may be various crystalline or amorphous alloy magnetic materials, or a material that combines a crystalline material and an amorphous material.

[0022] A crystalline alloy magnetic material that can be used as a magnetic material for the substrate 11 is, for example, a crystalline alloy material that contains 50 wt% or more, or 85 wt% or more, of Fe (iron) as the main component, and also contains one or more elements selected from the group consisting of Si (silicon), Al (aluminum), Cr (chromium), Ni (nickel), Ti (titanium), and Zr (zirconium). An amorphous alloy magnetic material that can be used as a magnetic material for the substrate 10 is, for example, an amorphous alloy material that contains either B (boron) or C (carbon) in addition to any of Si (silicon), Al (aluminum), Cr (chromium), Ni (nickel), Ti (titanium), or Zr (zirconium).

[0023] As the magnetic material for the substrate 11, pure iron consisting of Fe (iron) and unavoidable impurities can be used. Alternatively, a material combining pure iron consisting of Fe (iron) and unavoidable impurities with various crystalline or amorphous alloy magnetic materials can be used as the magnetic material for the substrate 11. The material of the substrate 11 is not limited to those explicitly stated herein, and any known material can be used as the substrate material.

[0024] The base body 11 can be manufactured, for example, by mixing the aforementioned magnetic or non-magnetic material powder with a lubricant, filling this mixture into the cavity of a mold for molding and press-molding to produce a compact, and then heat-treating this compact. Alternatively, the base body 11 can also be manufactured by mixing the aforementioned magnetic or non-magnetic material powder with a resin, glass, or insulating oxide (for example, Ni-Zn ferrite or silica), molding this mixture, and then heat-treating it. Depending on the raw materials used, the heat treatment may involve thermosetting at a temperature of 200°C or lower, or sintering at a temperature of 600°C or higher or 1000°C or higher.

[0025] The conductor 14 is made of a metallic material with excellent conductivity. For example, the metallic material for the conductor 14 may be one or more metals selected from Cu (copper), Al (aluminum), Ni (nickel), or Ag (silver), or an alloy containing any of these metals. An insulating coating may be provided on the surface of the conductor 14. The conductor 14 is provided on or inside the substrate 11. One conductor 14 may be provided per substrate 11, or multiple conductors 14 may be provided per substrate 11.

[0026] In one embodiment of the present invention, the base body 11 is referred to as a drum core and has a flange 11c and a winding core 11b. The winding core 11b can take any shape suitable for the conductor 14 to circulate around it, and in this embodiment extends in the height direction H. For example, the winding core 11b may be a polygonal prism shape such as a triangular prism, a pentagonal prism, or a hexagonal prism, or the winding core 11b may be cylindrical, elliptical, or truncated cone.

[0027] The flanges 11c are provided at both ends of the core 11b. In one embodiment of the present invention, flanges 11c are provided on both the upper surface 1a and the bottom surface 1b. The flanges 11c extend in a direction perpendicular to the core 11b.

[0028] In this specification, the terms “perpendicular,” “orthogonal,” and “parallel” are not used in a mathematically strict sense. For example, if the flange 11c extends in a direction perpendicular to the core 11b, the angle between the flange 11c and the core 11b may be 90°, but it is sufficient if it is approximately 90°.

[0029] The range of angles approximately 90° may include any angle within the ranges of 70° to 110°, 75° to 105°, 80° to 100°, or 85° to 95°. Similarly, the terms "parallel," "orthogonal," "straight line," "plane," and other mathematically rigorous terms included herein may be interpreted more broadly than their rigorous mathematical meanings, taking into account the spirit, context, and common technical knowledge of this invention.

[0030] In one embodiment of the present invention, the conductor 14 is formed by winding a conductor around the outer circumference of the core 11b of the base 11. As the conductor, a thick one is used, for example, with a diameter of 0.05 mm or more, or 0.1 mm or more, or even 0.2 mm or more, so that the resistance of the coil component 1 is low. The end 14a of the conductor 14 bypasses the flange 11c and reaches the bottom surface 1b, and at least a part of the end 14a is embedded in the external electrode 12 so that the conductor 14 and the external electrode 12 are joined.

[0031] The external electrode 12 is provided on the bottom surface 1b of the coil component 1 and has a shape that extends in the longitudinal direction L. In one embodiment of the present invention, since the coil component 1 is a two-terminal type, two external electrodes 12 are provided. In cases where the coil component 1 is a four-terminal type, more external electrodes 12 may be provided. The structure of the external electrode 12 will be described in detail later. The coil component 1 may be provided with an outer casing 13. If an outer casing 13 is provided, the outer casing 13 covers the conductor 14 so as to fit between the two flanges 11c. The outer casing 13 is provided in such a way that it does not affect the external dimensions of the coil component 1.

[0032] The outer casing 13 is formed, for example, by filling the space between two flanges 11c with resin. The outer casing 13 is made of resin or a resin containing a filler. Any resin material used to cover windings in wound-type coil components can be used as the material for the outer casing 13. Magnetic or non-magnetic materials can be used as the filler. The outer casing 13 is formed by applying a composite material containing resin, filler, etc., to the outside of the conductor 14 using a dispenser or the like, and then curing the resin component.

[0033] The exterior portion 13 may be formed from a material other than resin. The material of the exterior portion 13 other than resin may be metal, ceramics, or other materials. The exterior portion 13 may be formed, for example, by providing a foil, plate, or composite member made of metal, ceramics, or other materials between the two flanges 11c. <Variation> The shape of the base 11 and other components that make up the coil component 1 is not limited to the shapes shown in Figures 1 and 2. Figure 3 is a perspective view showing a modified coil component, and Figure 4 is a cross-sectional view and a side view of the coil component shown in Figure 3. Figure 4 shows a cross-section and a side view along the BB line shown in Figure 3.

[0034] The modified coil component 1 shown in Figures 3 and 4 also has a base 11, an external electrode 12, and an outer casing 13, and has a conductor 14 inside. In the modified case, the coil component 1 has a rectangular parallelepiped shape. However, even if a part of the outer surface of the coil component 1 is curved, or if the corners or edges of the coil component 1 are rounded, such a shape may also be referred to as a "rectangular parallelepiped shape." In other words, when "rectangular parallelepiped" or "rectangular parallelepiped shape" is used in this specification, it does not mean a "rectangular parallelepiped" in a mathematically strict sense.

[0035] In the modified example, the base 11 has a winding core 11b extending in the longitudinal direction L, and flanges 11c are provided at both ends of the winding core 11b extending in the longitudinal direction L. In addition, the external electrodes 12 in the modified example are provided on the bottom surface 1b side of each of the two flanges 11c, and each external electrode 12 extends in the width direction W.

[0036] The substrate 11 and the conductor 14 may be formed integrally by lamination. In lamination formation, multiple magnetic sheets made of the composite magnetic material described above are prepared, and a planar conductive pattern for forming the conductor is created on the surface of the magnetic sheet, for example by printing. Methods other than printing, such as plating, vapor deposition, or paste transfer, may be used to form the conductive pattern.

[0037] Furthermore, lead conductors are formed to connect each conductor pattern. The lead conductors are made, for example, by printing or filling. The printing of the lead conductors may be performed simultaneously with the printing of the conductor patterns or separately. Methods other than printing, such as plating, vapor deposition, or paste transfer, may also be used to form the lead conductors. The conductor patterns and lead conductors are formed such that the end 14a of the conductor 14 is located at the location where the external electrode 12 is formed on the bottom surface 1b.

[0038] Subsequently, a magnetic sheet and a magnetic sheet with a conductor pattern or drawn conductors are stacked and pressed together to obtain a laminate. The obtained laminate is then separated into individual pieces and heat-treated to obtain a substrate 11 containing the conductor 14. In the heat treatment of the laminate, the resin may be removed by thermal decomposition and the magnetic material may be sintered at a heat treatment of 600 to 850°C.

[0039] <Structure of external electrodes> Figure 5 is a schematic diagram showing the shape of the external electrode 12 in the coil component 1 shown in Figures 1 and 2, and Figure 6 is an enlarged cross-sectional view showing the structure of the external electrode 12. Figure 5(A) shows a bottom view of coil component 1, and Figure 5(B) shows a side view. However, in the side view of Figure 5(B), only the area around the bottom surface 1b of the base body 11 is shown, and other parts are omitted from the illustration. In one embodiment of the present invention, the external electrode 12 is formed on a groove 11a provided on the surface of a base body 11 which is the bottom surface 1b of the coil component 1. The groove 11a extends along the surface of the base body 11 in the longitudinal direction L, and the external electrode 12 also extends along the longitudinal direction L on the bottom surface 1b. In this embodiment, two external electrodes 12 are provided, and the two external electrodes 12 extend along each other in the same direction. Furthermore, the two external electrodes 12 are spaced apart from each other in the width direction W and form a pair of external electrodes 12.

[0040] The planar shape of the external electrode 12 has a narrow portion 12a where the width in the width direction W is minimal, and a wide portion 12b where the width in the width direction W is maximum. The narrow portion 12a is located between two adjacent wide portions 12b in the length direction L. For example, the narrow portion 12a is in the central part of the external electrode 12 in the length direction L, and the wide portions 12b are located on both sides of the narrow portion 12a in the length direction L. In other words, the width of the external electrode 12 increases from the central part in the length direction L towards both ends of the length direction L. The distance between the two wide portions 12b is 70% or more of the total length of the external electrode 12 in the length direction L.

[0041] The wide portion 12b of the external electrode 12 is not limited to two locations. The external electrode 12 may have, for example, three wide portions 12b and two narrow portions 12a between adjacent wide portions 12b. In one embodiment of the present invention, the thickness of the external electrode 12 in the height direction H is thicker near the wide portion 12b and thinner near the narrow portion 12a. In other words, the thickness of the external electrode 12 increases from the central portion in the length direction L towards both ends of the length direction L. The distance between the points where the thickness of the external electrode 12 is maximum is 60% or more of the total length of the external electrode 12 in the length direction L.

[0042] If there are two locations on a single external electrode 12 where the thickness of the external electrode 12 is maximum, these two maximum locations will contact the land portion 3 when mounted on the substrate 2a, maintaining the orientation of the coil component 1. As a result, when mounted on the substrate 2a, the positional accuracy of the coil component 1 in the height direction H or width direction W is improved, and the coil component 1 is mounted in a stable orientation. As shown in Figure 6, the external electrode 12 has a first layer 12c provided on the surface of the substrate 11 and a second layer 12d provided on the first layer 12c. The external electrode 12 is made of a metal material with excellent conductivity.

[0043] <Formation of external electrodes> Here, we will explain the procedure for forming the external electrode 12. Figures 7 to 9 illustrate the procedure for forming the external electrode 12. Each of Figures 7 to 9 shows a bottom view (A) and a side view (B), similar to Figure 5. As a preparatory step for forming the external electrode 12, a substrate 11 having grooves 11a is prepared, as shown in Figure 7. Then, as shown in Figure 8, the first layer 12c is formed along the grooves 11a of the substrate 11.

[0044] The metallic material for the first layer 12c may be any of Ag (silver), Cu (copper), Ti (titanium), Cr (chromium), Ni (nickel), Sn (tin), or a combination of any of these, or an alloy of any of these. The first layer 12c is formed, for example, by coating the metallic material by dipping, sputtering, or vapor deposition, and is formed to have a planar shape equivalent to the planar shape of the external electrode 12, for example, by using a mask.

[0045] The first layer 12c is formed on the surface of the substrate 11 with a thickness of 0.5 to 10 μm. The thickness of the first layer 12c is almost uniform except for the outer periphery of the planar shape, and the difference in thickness is within 10% of the average thickness. It is desirable that the first layer 12c contains Ag (silver), Cu (copper), or Ni (nickel) on the surface that contacts the second layer 12d.

[0046] As shown in Figure 9, a second layer 12d is formed on the first layer 12c. The metallic material of the second layer 12d mainly consists of Sn (tin), for example, containing 90 wt% or more, and also contains one of the following components other than Sn (tin): Ag (silver), Cu (copper), or Bi (bismuth). The metallic material of the second layer 12d melts at a temperature of 250°C or lower and is generally referred to as molten solder.

[0047] The second layer 12d is formed when the molten solder, which has become liquid, wets and spreads along the surface of the first layer 12c. At this time, due to the surface tension of the liquid molten solder, the second layer 12d becomes thicker near the wide portion 12b than in other areas. As a result, the second layer 12d becomes thinner near the narrow portion 12a, and the overall thickness of the external electrode 12 is also suppressed. Furthermore, as described above, the second layer 12d becomes thicker near each of the multiple wide sections 12b, which stabilizes the mounting position of the coil component 1.

[0048] Here, we will explain a comparative example of coil components. Figure 10 shows a comparative example coil component 1'. Figure 10(A) shows a bottom view, and Figure 10(B) shows a side view. The coil component 1' of the comparative example has an external electrode 12' whose size in the width direction W is uniform in the length direction L. The external electrode 12' in the comparative example is also formed of molten solder, and its thickness is maximum in the central part in the length direction L due to surface tension. In the comparative example, the thickness increase due to surface tension makes it difficult to suppress the overall thickness of the external electrode 12', and it is also difficult to suppress the height of the coil component 1' when mounted on the substrate 2a. Furthermore, in the comparative example, the orientation of the coil component 1' when mounted on the substrate 2a becomes unstable, as shown in Figure 10(B), and there is a risk that the coil component 1' will be mounted in a tilted position. In one embodiment of the present invention, the external electrode 12 has multiple wide portions 12b sandwiched between narrow portions 12a, resulting in a thinner external electrode 12' with a uniform width. Even when there are more than two wide portions 12b, the external electrode 12 remains thinner than an external electrode 12' with a uniform width. The ratio of the widths of the narrow portions 12a and wide portions 12b, as well as their specific shapes, are appropriately selected to ensure the external electrode 12 is sufficiently thin.

[0049] Let's return to the explanation of coil component 1, referring to Figures 5 to 9. In one embodiment of the present invention, the external electrode 12 is provided on the groove 11a of the base 11, so the protrusion from the bottom surface 1b of the coil component 1 is kept low, and the height of the coil component 1 when mounted is also suppressed.

[0050] While the molten solder of the first layer 12c is still liquid, the end 14a of the conductor 14 is inserted into the molten solder. This joins the conductor 14 to the external electrode 12. The end 14a of the conductor 14 is embedded, for example, in at least one of the wide portion 12b and the thickest portion of the external electrode 12. Alternatively, the end 14a of the conductor 14 is joined to the external electrode 12 at a location that avoids the central portion which becomes the narrow portion 12a. As a result, the thickness of the external electrode 12 is suppressed while the conductor 14 and the external electrode 12 are reliably joined, and the connection between the conductor 14 and the external electrode 12 is stable. Therefore, even when a thick wire is used as the conductor 14, the joining of the conductor 14 and the external electrode 12 is easy and good. Even if the thickness of the solder is thin, the strength of the connection can be increased by joining at the wide portion 12b.

[0051] <Other Embodiments> The following describes other embodiments of the coil component. The other embodiments described below are similar to the above embodiments except for the difference in the structure of the external electrodes, so the following explanation will focus on the differences and omit redundant explanations. Also, Figures 11 to 15, which are referenced below, show a bottom view (A) and a side view (B), similar to Figure 5.

[0052] Figure 11 shows the external electrode 102 in the coil component 100 of the second embodiment. In the coil component 100 of the second embodiment, the surface of the base body 11 is planar, and the external electrode 102 is formed on the planar surface of the base body 11. The planar shape of the external electrode 102 in the second embodiment is the same as the planar shape of the external electrode 12 in the first embodiment, having a narrow portion 102a and a wide portion 102b. Therefore, the molten solder is drawn from the narrow portion 102a side to the wide portion 102b side by the surface tension of the liquid molten solder. By adjusting the ratio of the widths in the narrow portion 102a and the wide portion 102b, the thickness of the external electrode 102 becomes almost uniform along the length L in the second embodiment. Even in the second embodiment, where the thickness of the external electrode 102 is uniform, the thickness in the central portion along the length L is suppressed, thus reducing the overall thickness of the external electrode 102. The coil component 100 of the second embodiment is easy to manufacture because a groove 11a is not required in the base 11.

[0053] Figure 12 shows the external electrode 202 in the coil component 200 of the third embodiment. In the coil component 200 of the third embodiment, a groove 11a is formed in the base body 11, similar to the first embodiment, and the external electrode 202 is formed along the groove 11a of the base body 11. Furthermore, the planar shape of the external electrode 202 in the third embodiment is similar to the planar shape of the external electrode 12 in the first embodiment, having a narrow portion 202a and a wide portion 202b. As a result, the surface tension of the liquid molten solder pulls the molten solder from the narrow portion 202a side to the wide portion 202b side, and the thickness of the external electrode 202 in the height direction H is thicker near the wide portion 202b and thinner near the narrow portion 202a.

[0054] In the third embodiment, the sides 202c of the two external electrodes 202 that are located on the outside of each other (i.e., on the outside in the width direction W) extend in a straight line. That is, the inside of the two external electrodes 202 are recessed outwards in the width direction W at the central part in the length direction L. Having straight sides 202c on the outside of each other of the external electrodes 202 makes it easy to design the dimensions to match the land portion 3 on the substrate 2a.

[0055] The straight edges 202c of the two external electrodes 202 are parallel to each other. Therefore, when the coil component 200 is mounted on the substrate 2a, the orientation of the edges 202c of the external electrodes 202 is aligned with the land portion 3, resulting in high mounting strength. In other words, the contact state of the external electrodes 202 with the land portion 3 is almost the same over the entire length L, and the bonding between the external electrodes 202 and the land portion 3 is uniform, resulting in high mounting strength.

[0056] Figure 13 shows the external electrode 302 in the coil component 300 of the fourth embodiment. In the coil component 300 of the fourth embodiment, similar to the second embodiment, the surface of the base body 11 is planar, and the external electrode 302 is formed on the planar surface of the base body 11. The planar shape of the external electrode 302 in the fourth embodiment is similar to that of the external electrode 202 in the third embodiment, having a narrow portion 302a and a wide portion 302b. Therefore, the molten solder is drawn from the narrow portion 302a side to the wide portion 302b side by the surface tension of the liquid molten solder.

[0057] By adjusting the ratio of the widths in the narrow portion 302a and the wide portion 302b, the thickness of the external electrode 302 becomes almost uniform along the length L in the fourth embodiment. In the fourth embodiment as well, the thickness in the central portion along the length L is suppressed, thus reducing the overall thickness of the external electrode 302. The coil component 300 of the fourth embodiment is easier to manufacture than the third embodiment because the base body 11 does not require a groove 11a.

[0058] Figure 14 shows the external electrode 402 in the coil component 400 of the fifth embodiment. In the coil component 400 of the fifth embodiment, a groove 11a is formed in the base body 11, similar to the first embodiment, and the external electrode 402 is formed along the groove 11a of the base body 11. In the fifth embodiment as well, the planar shape of the external electrode 402 has a narrow portion 402a and a wide portion 402b. However, in the fifth embodiment, the wide portion 402b is located at both ends in the length direction L of the external electrode 402. Therefore, in the fifth embodiment, the molten solder is pulled more strongly towards both ends compared to the first embodiment. In the fifth embodiment, the locations where the thickness of the external electrode 402 is maximum are located closer to both ends than in the first embodiment, and the thickness of the narrow portion 402a is thinner than in the first embodiment. The overall thickness of the external electrode 402 is also suppressed in the fifth embodiment compared to the first embodiment.

[0059] In the fifth embodiment, the distance between the points where the thickness of the external electrode 402 is maximum is wider than in the first embodiment. As a result, the orientation of the coil component 400 during mounting becomes more stable. In the fifth embodiment, similar to the third embodiment, the two external electrodes 402 have sides 402c that extend linearly outward from each other (i.e., outward in the width direction W). Therefore, the coil component 400 in the fifth embodiment has high mounting strength.

[0060] Figure 15 shows the external electrode 502 in the coil component 500 of the sixth embodiment. In the coil component 500 of the sixth embodiment, similar to the second embodiment, the surface of the base body 11 is planar, and the external electrode 502 is formed on the planar surface of the base body 11. The planar shape of the external electrode 502 in the sixth embodiment is similar to that of the external electrode 402 in the fifth embodiment, having a narrow portion 502a, a wide portion 502b, and a straight edge 502c. Therefore, the coil component 500 in the sixth embodiment has high mounting strength, similar to that of the fifth embodiment. In the sixth embodiment, although the base body 11 does not have grooves 11a, the molten solder is strongly attracted to both ends, similar to the fifth embodiment. As a result, the thickness of the external electrode 502 is minimal in the central part of the length L and maximum on both sides of the central part. Therefore, the coil component 500 of the sixth embodiment is easier to manufacture than that of the fifth embodiment because the base body 11 does not have grooves 11a, and its orientation during mounting is stable, similar to the fifth embodiment. [Explanation of Symbols]

[0061] 1, 100, 200, 300, 400, 500 coil parts 2 Circuit boards 2a board 3 Land Section 11 Base 11a Groove 12, 102, 202, 302, 402, 502 external electrode 12a, 102a, 202a, 302a, 402a, 502a Narrow part 12b, 102b, 202b, 302b, 402b, 502b Wide section 202c, 302c, 402c, 502c - Straight edges 13 Exterior part 14 Conductors 14a End

Claims

1. Substrate and, A conductor provided on at least one of the interior and surface of the substrate, It consists of a base layer and a solder layer provided on the base layer, is provided on the first surface of the substrate and extends in a first direction, the width in a second direction perpendicular to the first direction is maximized at multiple locations in the first direction, and the width in the second direction is minimized at a location between two adjacent maximum locations in the first direction, defining a minimum location, and an external electrode connected to the conductor, Equipped with, A coil component characterized in that, when the external electrode is viewed from a direction perpendicular to the first surface, the width of the external electrode in the second direction increases from the smallest point toward the largest point.

2. The coil component according to claim 1, characterized in that the width of the external electrode is narrower in the central portion in the first direction than in the portions on both sides of the central portion.

3. The external electrodes include at least one pair of external electrodes, The coil component according to claim 1 or 2, characterized in that the pair of external electrodes are spaced apart from each other in the second direction, each extending in the first direction, and the thickness in the third direction perpendicular to the first and second directions is thinner at the minimum location than at the maximum location adjacent to the minimum location.

4. The external electrodes include at least one pair of external electrodes, The coil component according to any one of claims 1 to 3, characterized in that the pair of external electrodes are spaced apart from each other in the second direction, each extends in the first direction, and the sides located outside each other in the second direction extend linearly in the first direction.

5. The substrate has a groove that is recessed from the first surface toward the interior of the substrate and extends in the first direction, The coil component according to any one of claims 1 to 4, characterized in that the external electrode's maximum portion covers a part of the groove in the first direction.

6. The coil component according to any one of claims 1 to 5, characterized in that the conductor is connected to the solder at the maximum location of the external electrode.

7. A coil component according to any one of claims 1 to 6, A circuit board on which the aforementioned coil component is mounted, A circuit board characterized by comprising the following features.

8. An electronic device characterized by comprising the circuit board described in claim 7.

9. A manufacturing method for producing a coil component according to any one of claims 1 to 6, The process of forming a base layer on the first surface that extends in the first direction, where the width in the second direction is maximized at multiple locations in the first direction, and where the width in the second direction is minimized at a location between two adjacent maximum locations in the first direction, thereby defining a minimum location; The process of forming a solder layer on the aforementioned underlayer by melting solder, It has, A method for manufacturing a coil component, characterized in that, when the base layer is viewed from a direction perpendicular to the first surface, the width of the base layer formed by the process of forming the base layer in the second direction increases from the smallest point toward the largest point.

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