Method for manufacturing coil component

Abstract

To prepare an exterior unit by using a resin material selected with a high degree of freedom while suppressing protrusion.SOLUTION: A coil component includes: a magnetic base body having a shaft and a first flange that extends in a direction intersecting a shaft direction in which the shaft extends and being in contact with a first end of the shaft; a coil conductor having a winding portion formed of a conductive wire around the shaft and a lead-out portion through which the conductive wire is led out from the winding portion to the first flange; an external electrode provided on part of an outer surface of the first flange and to which an end portion of the lead-out portion is connected; and an exterior portion made of a resin material around the winding portion. A method for manufacturing the coil component includes: an application step of applying a liquid resin material around the winding portion so as to be in contact with the first flange in a posture in which the shaft is positioned below the first flange; and a curing step of curing the resin material.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a coil component.

Background Art

[0002] As the applications of electronic components expand and the performance of electronic devices improves, the quantity of electronic components used has been increasing. In addition, there are demands for higher performance, smaller size, and higher quality in electronic components. The same applies to coil components. Some surface-mounted coil components have a winding portion covered with a resin exterior portion for the purpose of protecting the winding portion and improving electrical performance. In addition, the exterior portion may be formed by curing a liquid resin material with heat. Generally, the application and heat curing of the resin material that becomes the exterior portion are performed with the mounting surface of the coil component facing downward.

[0003] However, the resin material may flow into the mounting surface side during application or curing. As a result, there is a risk that the connection between the electrode and the winding may be inhibited, or electrical connection failures or appearance defects may occur. In addition, if the resin material that has flowed into the mounting surface side adheres between the coil component and the conveying member and is cured, there is also a risk of conveyance errors of the coil component.

[0004] Therefore, controlling the shape and position of the resin material during the formation of the exterior portion is a very important factor for ensuring the quality of coil components and the stable operation of equipment. For example, in Patent Document 1, in order to prevent the resin material from protruding in either the outer shape direction or the length direction of the coil component and causing the coil component to be defective, a method is shown in which the coil component is placed horizontally and the resin material is applied and filled by a dispenser.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the method disclosed in Patent Document 1, a solvent is added to the resin composition, and the viscosity of the resin material is adjusted to a specific viscosity different from that of general resin materials. That is, the method of Patent Document 1 has strong restrictions on the resin material due to the manufacturing method, so the applicable range is narrow. In view of the above circumstances, an object of the present invention is to create an exterior portion using a resin material that can be selected with a high degree of freedom while suppressing protrusion and the like in a method for manufacturing a coil component.

Means for Solving the Problems

[0007] In order to solve the above problems, a method for manufacturing a coil component according to an aspect of the present invention includes a magnetic base having a shaft and a first flange that extends in a direction intersecting the axial direction in which the shaft extends and contacts the first end of the shaft, a winding portion formed from a conducting wire around the shaft, a lead-out portion from which the conducting wire is drawn from the winding portion to the first flange, an external electrode provided on a part of the outer surface of the first flange to which an end of the lead-out portion is connected, and an exterior portion formed from a resin material around the winding portion. The method for manufacturing a coil component includes a coating step of applying a liquid resin material around the winding portion so as to contact the first flange in a posture in which the shaft is positioned below the first flange, and a curing step of curing the resin material.

[0008] According to the method for manufacturing a coil component according to an aspect of the present invention, the external electrode is provided on the outer surface of the first flange on the side opposite to the inner surface that contacts the first end. According to the method for manufacturing a coil component according to an aspect of the present invention, the magnetic base further has a second flange that extends in a direction intersecting the axial direction and contacts the second end of the shaft opposite to the first end of the shaft, and in the coating step, the resin material is provided in a space sandwiched between the first flange and the second flange, extending from the first flange toward the second flange.

[0009] Also, according to the method for manufacturing a coil component according to one aspect of the present invention, the second flange fits within the outer shape of the first flange as the outer shape viewed in the axial direction. Also, according to the method for manufacturing a coil component according to one aspect of the present invention, in the curing step, the resin material is heated and cured with the axis positioned downward with respect to the first flange.

[0010] Also, according to the method for manufacturing a coil component according to one aspect of the present invention, the magnetic substrate has an overall length in the direction of the axis of 2 mm or less. Also, according to the method for manufacturing a coil component according to one aspect of the present invention, the length of the axis exceeds 80% of the overall length in the direction of the axis of the magnetic substrate.

[0011] Also, according to the method for manufacturing a coil component according to one aspect of the present invention, the resin material contains a thermosetting resin component, and the coil component has a weight change of less than 1% when placed in an environment of 180°C for 1 hour. Also, according to the method for manufacturing a coil component according to one aspect of the present invention, the coating step includes a first coating step of coating a liquid first resin material so as to be in contact with the first flange, and a second coating step of coating a liquid second resin material so as to be in contact with the first resin material on the lower side in the gravitational direction with respect to the liquid first resin material or the cured first resin material.

[0012] Also, according to the method for manufacturing a coil component according to one aspect of the present invention, the curing step includes a first curing step of curing the first resin material coated in the first coating step before the second coating step, and a second curing step of curing the second resin material coated in the second coating step.

Advantages of the Invention

[0013] According to the present invention, in the method for manufacturing a coil component, an exterior portion can be created using a resin material selected with a high degree of freedom while suppressing protrusion and the like.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

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, such as usage conditions and usage environments.

[0016] The technical scope of the present invention is defined by the scope of 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 appropriately made in the description of the subsequent drawings.

[0017] <First Example of Coil Component> FIG. 1 is a perspective view showing a first example of a coil component manufactured according to an aspect of the manufacturing method of the present invention, and FIG. 2 is a cross-sectional view of the first example of the coil component. FIG. 2 shows a cross-section taken along line A-A shown in FIG. 1.

[0018] The coil component 1 is mounted on a substrate 2a. For example, two land portions 3 are provided on the substrate 2a. The coil component 1 has, for example, two external electrodes 40. The coil component 1 is mounted on the substrate 2a by joining each external electrode 40 and the land portion 3 with solder. The circuit board 2 includes the coil component 1 and the substrate 2a on which the coil component 1 is mounted. The circuit board 2 is provided in various electronic devices. Examples of electronic devices equipped with the circuit board 2 include automotive electrical components, servers, board computers, and various other electronic devices.

[0019] In this specification, unless otherwise interpreted in the context, the description of directions is based on the “L-axis” direction, “W-axis” direction, and “H-axis” direction in FIG. 1, and is referred to as the “length” direction, “width” direction, and “height” direction, respectively. Also, the plane defined by the L-axis and the W-axis is referred to as the LW plane.

[0020] The dimensions of the coil component 1 in each direction are such that the dimension in the length direction L is in the range of, for example, 1.0 mm or more and 4.5 mm or less, the dimension in the width direction W is in the range of, for example, 0.5 mm or more and 3.2 mm or less, and the dimension in the height direction H is in the range of, for example, 0.5 mm or more and 2.0 mm or less. Also, the dimension in the height direction H is smaller than the dimension in the length direction L, and further, the dimension in the height direction H is smaller than the dimension in the width direction W.

[0021] The coil component 1 manufactured according to an aspect of the manufacturing method of the present invention is a wound-type coil component. The coil component 1 of the first example includes a magnetic substrate 11, an exterior portion 20, a coil conductor 30, and an external electrode 40. In the case of the first example, the magnetic substrate 11 is a drum core and has a first flange 12, a shaft 13, and a second flange 14.

[0022] The axis 13 of the magnetic substrate 11 extends, for example, in the H direction, with a first flange 12 connected to the first end on the -H side and a second flange 14 connected to the second end on the +H side. The first flange 12 and the second flange 14 extend in the outer peripheral direction of the axis 13. That is, the first flange 12 and the second flange 14 extend in a direction intersecting the axial direction in which the axis 13 extends, and for example, extend along the LW plane with respect to the axis 13 extending in the H direction. The length of the axis 13, that is, the dimension in the height direction H, is, for example, greater than 80% of the length of the entire magnetic substrate 11.

[0023] The first flange 12 and the second flange 14 have outer surfaces 12a, 14a and inner surfaces 12b, 14b. The outer surfaces 12a, 14a of the first flange 12 and the second flange 14 form the outer surface of the coil component 1, and the inner surfaces 12b, 14b of the first flange 12 and the second flange 14 face the inner side of the coil component 1. The inner surface 12b of the first flange 12 contacts the first end of the axis 13, and the inner surface 14b of the second flange 14 contacts the second end of the axis 13. In the following description, the outer surface 12a and the inner surface 12b of the first flange 12 may be referred to as the first outer surface 12a and the first inner surface 12b, and the outer surface 14a and the inner surface 14b of the second flange 14 may be referred to as the second outer surface 14a and the second inner surface 14b.

[0024] When viewed in the direction in which the axis 13 extends, or in the direction toward the first outer surface 12a, the outer shape of the second flange 14 fits inside the outer shape of the first flange 12. In other words, the second flange 14 fits inside the outer shape of the first flange 12 as the outer shape when viewed in the axial direction in which the axis 13 extends. Therefore, the outer dimensions of the second flange 14 have almost no influence on the outer dimensions of the coil component 1. The magnetic substrate 11 is a member formed as a single aggregate using a magnetic material.

[0025] As the magnetic material for the magnetic substrate 11, for example, ferrite and soft magnetic alloy materials are used. The magnetic material for the magnetic substrate 11 may be various crystalline or amorphous alloy magnetic materials, or a material combining a crystalline material and an amorphous material. The crystalline alloy magnetic material that can be used as the magnetic material for the magnetic substrate 11 is, for example, a crystalline alloy material containing 50 wt% or more, or 85 wt% or more of Fe as the main component and containing one or more elements selected from the group consisting of Si, Al, Cr, Ni, Ti, and Zr. The amorphous alloy magnetic material that can be used as the magnetic material for the magnetic substrate 11 is, for example, an amorphous alloy material containing either B or C in addition to any one of Si, Al, Cr, Ni, Ti, and Zr.

[0026] As the magnetic material for the magnetic substrate 11, pure iron composed of Fe and inevitable impurities can also be used. As the magnetic material for the magnetic substrate 11, a material combining pure iron composed of Fe and inevitable impurities with various crystalline or amorphous alloy magnetic materials may be used. The material of the magnetic substrate 11 is not limited to those explicitly described in this specification, and any known material can be used.

[0027] The coil conductor 30 is made of a metal material with excellent conductivity. As the metal material for the coil conductor 30, for example, one or more metals among Cu, Al, Ni, and Ag, or an alloy containing any of these metals can be used. The coil conductor 30 has a winding portion 31 in which a wire having an insulating film on its surface is wound around the axis 13 of the magnetic substrate 11, and a lead-out portion 32 in which the end of the wire is drawn out to the first flange 12 side from the winding portion 31. In other words, the coil conductor 30 has a winding portion 31 formed from the wire around the axis 13 and a lead-out portion 32 in which the wire is drawn out from the winding portion 31 to the first flange 12. The cross-sectional shape of the wire is, for example, circular or rectangular. One coil conductor 30 may be provided for one magnetic substrate 11, or a plurality of coil conductors 30 may be provided for one magnetic substrate 11.

[0028] The external electrode 40 is provided on the first flange 12 side, and the lead-out portion 32 is connected to the external electrode 40. The external electrode 40 is formed using a conductive material or a metal plate. In the case of the first example, the external electrode 40 has, for example, an underlayer and a solder layer. As an example, the external electrode 40 is provided on the first outer surface 12a. The external electrode 40 may be provided on the side surface 12c of the first flange 12. In this specification, "provided on a surface" and "provided on a face" mean a portion that can be seen when looking at the surface and exists within the range of the surface. That is, it may be provided so as to protrude or recess in the normal direction of the surface. Further, when the magnetic substrate 11 has protrusions or depressions on the surface and the external electrode 40 is provided so as to cover the outer surface of the protrusion or the inner surface of the depression, it also corresponds to "provided on a surface" and "provided on a face".

[0029] When the external electrode 40 is provided on the first outer surface 12a, the first outer surface 12a becomes the mounting surface of the coil component 1, and the coil component 1 is mounted in a posture where the first outer surface 12a faces the substrate 2a. The exterior portion 20 is provided outside the circumferential portion 31 of the coil conductor 30. When viewed in the direction in which the axis 13 of the magnetic substrate 11 extends, the exterior portion 20 is within the outer shape of the first flange 12 of the magnetic substrate 11. For this reason, the outer dimension of the coil component 1 when viewed in the direction in which the axis 13 extends is substantially determined by the outer dimension of the first flange 12 of the magnetic substrate 11, and the variation in the outer dimension of the coil component 1 is small. That is, the individual differences between products are reduced. Even when the influence of the lead-out portion 32 of the coil conductor 30 is considered, for any direction perpendicular to the direction in which the axis 13 extends, the outer dimension of the coil component 1 is, for example, within +5% with respect to the outer dimension of the first flange 12.

[0030] Further, regarding the height dimension in the direction in which the axis 13 extends, that is, the dimension in the height direction H, the height dimension of the coil component 1 substantially coincides with the height dimension of the magnetic substrate 11. As a result, the coil component 1 has little variation in height dimension. The height dimension of the coil component 1 is, for example, within +5% with respect to the height dimension of the magnetic substrate 11.

[0031] The exterior part 20 is formed by curing a resin material. That is, the exterior part 20 is made of a resin material around the circumferential part 31. As an example, the exterior part 20 contains a resin component and a filler and covers the periphery of the circumferential part 31. As the resin component of the exterior part 20, for example, a thermosetting resin is used. The resin component of the exterior part 20 may be a combination of multiple types of resins and may also contain any one or a combination of a curing agent, a stabilizer, and a thickener.

[0032] As the filler of the exterior part 20, for example, magnetic particles, silica particles, etc. are used. The proportion of the filler in the exterior part 20 is, for example, 50% or more and 60% or less as the area ratio of the cross-section. The presence of the filler in the exterior part 20 can be confirmed, for example, by the difference in contrast with the resin on an image obtained by magnifying a cross-section in a range not including the surface of the exterior part 20 by 1000 times or more.

[0033] The exterior part 20 is formed of a material with little change in the usage environment of the coil component 1. In particular, it is desirable not to contain a resin component that softens at a temperature of 180°C. For example, even when placed at a temperature of 180°C for 1 hour, it is desirable that the weight change of the exterior part 20 is less than 1%. Similarly, in the coil component 1 as well, even when placed at a temperature of 180°C for 1 hour, it is desirable that the weight change of the coil component 1 is less than 1%.

[0034] The weight change in the exterior part 20 is confirmed, for example, using an environment with a temperature of 25°C and a humidity of 60% before the test and an environment with a temperature of 180°C and a humidity of 60% or less for the test. The weight change in the exterior part 20 may be obtained from the weight change of the coil component 1 before and after the test, or the weight change before and after the test in the exterior part 20 taken out from the coil component 1 may be obtained.

[0035] <Second Example of Coil Component> Next, a second example of the coil component will be described. However, duplicate descriptions will be omitted for the elements already described in relation to the coil component 1 of the first example.

[0036] FIG. 3 is a perspective view showing a second example of a coil component manufactured by an aspect of the manufacturing method of the present invention, and FIG. 4 is a cross-sectional view of the second example of the coil component. FIG. 2 shows a cross-section along the line B-B shown in FIG. 1. The coil component 101 of the second example is also mounted on the substrate 2a to form the circuit board 2.

[0037] The coil component 101 of the second example has a rectangular parallelepiped outer shape. That is, the coil component 101 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. Any of the outer surfaces of the coil component 101 may be a flat plane or a curved curved surface. Also, the eight corner portions and the twelve ridge line portions of the coil component 101 may have rounded corners. That is, in this specification, the rectangular parallelepiped shape does not mean a mathematically strict rectangular parallelepiped, but means a shape that can be practically treated as a rectangular parallelepiped.

[0038] In the rectangular parallelepiped-shaped coil component 101, the dimensions in each direction are such that the dimension in the length direction L is in the range of, for example, 1.0 mm or more and 4.5 mm or less, the dimension in the width direction W is in the range of, for example, 0.5 mm or more and 3.2 mm or less, and the dimension in the height direction H is in the range of, for example, 0.5 mm or more and 2.0 mm or less. Also, the dimension in the height direction H is smaller than the dimension in the length direction L, and the dimension in the height direction H is smaller than the dimension in the width direction W.

[0039] The coil component 101 of the second example is also a wound-type coil component. The coil component 101 of the second example includes a magnetic substrate 111, an exterior portion 120, a coil conductor 30, and external electrodes 140. In the case of the second example, the magnetic substrate 111 is a T-core and has a first flange 12 and a shaft 13 but does not have a second flange 14. The magnetic material and the like of the magnetic substrate 111 in the second example are the same as those of the magnetic substrate 11 in the first example.

[0040] In the case of the second example, the external electrode 140 is provided from the outer surface 12a to the side surface 12c of the first flange 12. As an example, the external electrode 140 has a metal layer made of one or more metals among Ag, Cu, Ti, Ni, and Sn. The external electrode 140 may be a combination of a plurality of metal layers, or may be a combination of a metal layer containing resin in part. The external electrode 140 is composed of one or both of a layer having the same component as the coil conductor 30 and a layer having a higher resistance than the coil conductor 30. Also, the external electrode 140 is composed of one or both of a layer having the same filling rate as the coil conductor 30 and a layer having a lower filling rate than the coil conductor 30.

[0041] The exterior part 120 in the second example is formed of the same material as the exterior part 20 in the first example. In the case of the second example, the exterior part 120 covers the outside of the circumferential part 31 and also covers the second end side of the axis 13 of the magnetic base 111. Also in the second example, when viewed in the direction in which the axis 13 of the magnetic base 11 extends, the exterior part 120 is within the outer shape of the first flange 12. For this reason, the outer dimensions of the coil component 101 when viewed in the direction in which the axis 13 extends are determined substantially by the outer dimensions of the first flange 12 of the magnetic base 11. Also in the second example, the variation in the outer dimensions of the coil component 101 is small. Even when considering the influence of the lead-out part 32 of the coil conductor 30 and the influence of the external electrode 140 reaching the side surface 12c of the first flange 12, for any direction perpendicular to the direction in which the axis 13 extends, the outer dimensions of the coil component 101 are within +5% with respect to the outer dimensions of the first flange 12.

[0042] <Manufacturing method of coil component> Hereinafter, an embodiment of the manufacturing method of the coil component will be described. The object to be manufactured is, for example, the coil component 1 in the first example above.

[0043] FIG. 5 is a diagram showing the forming process of the magnetic base 11. The magnetic substrate 11 is formed, for example, by mixing the powder of the above-described magnetic material with a lubricant, filling the mixed material into the cavity of a mold for molding and press-molding to produce a compacted powder body, and heat-treating the compacted powder body. Further, the magnetic substrate 11 can also be formed, for example, by mixing the powder of the above-described magnetic material with a resin, glass, or insulating oxide, molding the mixed material, and heat-treating it. The insulating oxide is, for example, Ni-Zn ferrite or silica. As the heat treatment, depending on the raw materials used, heat curing at a temperature of 200°C or lower may be employed, or sintering at a temperature of 600°C or higher or 1000°C or higher may be employed.

[0044] FIG. 6 is a diagram showing the formation process of the base layer 41. In the first flange 12 of the magnetic substrate 11, a groove 12d is formed on the outer surface 12a side, and the base layer 41 is provided on the inner surface of the groove 12d. As the base layer 41, a metal material such as Ag, Cu, Ti, or Ni is used. The base layer 41 is provided by plating, coating with a metal material, sputtering, or vapor deposition. The base layer 41 integrates the external electrode 40 with the magnetic substrate 11 by adhering to the surface of the magnetic substrate 11.

[0045] FIG. 7 is a diagram showing the formation process of the coil conductor 30. A conducting wire is wound around the axis 13 of the magnetic substrate 11 to form a winding portion 31, and the coil conductor 30 is formed by pulling the conducting wire from the winding portion 31 to the first flange 12 side of the magnetic substrate 11 to form a lead-out portion 32. The winding portion 31 is provided between the first flange 12 and the second flange 14. The lead-out portion 32 is extended until the end reaches the outer surface 12a of the first flange 12.

[0046] FIG. 8 is a diagram showing the first resin application process. In the first resin application process, with the axis 13 positioned on the lower side in the direction of gravity with respect to the first flange 12 of the magnetic substrate 11, that is, with the axis 13 positioned downward, the resin material 51 is applied, for example, by a dispenser 50. The resin material 51 may be applied by transfer.

[0047] The resin material 51 is applied around the circumferential portion 31 of the coil conductor 30 at a position in contact with the inner surface 12b of the first flange 12. That is, the resin material 51 is applied to the first inner surface 12b and the circumferential portion 31. The first resin application step corresponds to an example of the first coating step according to the present invention. In the first resin application step, for example, while the magnetic substrate 11 is rotated about the shaft 13, the resin material 51 is applied from the dispenser 50, so that the resin material 51 is applied around the circumferential portion 31 of the coil conductor 30. When the magnetic substrate 11 rotates, the posture is maintained such that the shaft 13 is positioned on the lower side in the gravitational direction with respect to the first flange 12.

[0048] The resin material 51 contains a resin component, a solvent, and a filler. The resin material 51 is in a liquid state at the stage of being applied around the circumferential portion 31. Further, the resin material 51 contains, for example, a thermosetting resin. The resin material 51 may be a combination of a plurality of types of resin components, and may further contain a curing agent, a stabilizer, or a thickener.

[0049] The resin material 51 is applied so as to be contained inside the outer shape of the first flange 12 when viewed in the direction in which the shaft 13 extends. Thereby, in the finally obtained coil component 1, it is suppressed that the exterior portion 20 protrudes from the first flange 12 of the magnetic substrate 11 and affects the external dimensions.

[0050] During and after the application, the resin material 51 is attracted to the second flange 14 side of the magnetic substrate 11 by gravity, so that the resin material 51 does not protrude or flow into the first outer surface 12a side. As a result, connection failures and appearance failures due to the resin material 51 on the first outer surface 12a are suppressed. When the external electrode 40 is formed on the first outer surface 12a, adhesion of the resin material 51 to the external electrode 40 is avoided, so that the suppression effect of connection failures and appearance failures is particularly remarkable.

[0051] In the first resin application step, since the resin material 51 is applied so as to contact the upper first inner surface 12b and the periphery of the circumferential portion 31 in the gravitational direction, the degree of freedom in selecting the viscosity and the like of the resin material 51 is high. The resin material 51 has a viscosity greater than 1 Pa·s, for example, in an environment with a temperature of 20°C or higher and 40°C or lower. Further, when considering the ease of applying the resin material 51, the viscosity range is preferably 2 Pa·s or higher and 30 Pa·s or lower. In particular, when the size of one side of the coil component 1 exceeds 5 mm, the viscosity range is preferably 5 Pa·s or higher and 25 Pa·s or lower.

[0052] In the first resin application step, since the first inner surface 12b is positioned upward in the gravitational direction, when the resin material 51 is applied and adhered to the boundary portion between the first inner surface 12b and the circumferential portion 31, air and the like can escape efficiently, and the generation of voids and the like is also suppressed.

[0053] FIG. 9 is a diagram showing the first curing step. In the first curing step, for example, the resin material 51 is heated and cured in the heating furnace 60 to form the first exterior portion 21. Also in the first curing step, the posture in which the shaft 13 is positioned on the lower side in the gravitational direction with respect to the first flange 12 of the magnetic base 11 is maintained. That is, the resin material 51 is heated and cured in a posture in which the shaft 13 is positioned on the lower side in the gravitational direction with respect to the first flange 12.

[0054] That is, from the liquid resin material 51 to the formation of the first exterior portion 21, since the orientation of the magnetic base 11 does not change, the movement of the resin material 51 is suppressed, and the formation of the first exterior portion 21 is stabilized. Therefore, the formation of the exterior portion 20 of the coil component 1 is stabilized. In particular, even when the ratio of the shaft 13 in the extending direction of the shaft 13 of the magnetic base 11 to the total length of the magnetic base 11 is large, the formation of the exterior portion 20 is stabilized.

[0055] FIG. 10 is a diagram showing the second resin application step. Also in the second resin application step, the resin material 52 is applied, for example, by the dispenser 50 in a posture in which the shaft 13 is positioned on the lower side in the gravitational direction with respect to the first flange 12 of the magnetic base 11. In the second resin application step, the resin material 52 is applied around the circumferential portion 31 of the coil conductor 30 at a position in contact with the first exterior portion 21. That is, the resin material 52 is applied to the first exterior portion 21 and the circumferential portion 31. The second resin application step corresponds to an example of the second coating step according to the present invention. In the second resin application step, the resin material 52 is applied so as to sequentially cover the circumferential portion 31 of the coil conductor 30 following the first exterior portion 21 from the upper side to the lower side in the gravitational direction. As a result, the resin material 52 during and after application is attracted to the second flange 14 side of the magnetic base 11 by gravity, and the overflow and inflow of the resin material 52 to the first outer surface 12a side are suppressed. Therefore, connection failures and appearance defects due to the resin material 52 on the first outer surface 12a are suppressed. Also, in the second resin application step, the axis 13 may be positioned in a direction different from the gravitational direction with respect to the first flange 12 of the magnetic base 11. For example, the axis 13 may be in the range from the downward direction to the horizontal direction.

[0056] Also, the resin material 52 is provided in the space sandwiched between the first flange 12 and the second flange 14, extending from the first flange 12 toward the second flange 14. More specifically, the resin material 52 is applied so as to fit within the region R between the first inner surface 12b and the second inner surface 14b. Thereby, in the finally obtained coil component 1, it is suppressed that the exterior portion 20 protrudes from the magnetic base 11 and affects the outer dimensions.

[0057] In the second resin application step, since the resin material 52 is applied so as to contact the surroundings of the first exterior portion 21 and the circumferential portion 31 above in the gravitational direction, there is a high degree of freedom in selecting the viscosity and the like for the resin material 52. The resin material 52 in the second resin application step may be of the same type or a different type from the resin material 51 in the first resin application step.

[0058] The resin material 52 has a viscosity greater than 1 Pa·s, for example, in an environment with a temperature of 20°C or higher and 40°C or lower. Further, when considering the ease of applying the resin material 52, the viscosity range is preferably 2 Pa·s or higher and 30 Pa·s or lower. In particular, when the size of one side of the coil component 1 exceeds 5 mm, the viscosity range is preferably 5 Pa·s or higher and 25 Pa·s or lower.

[0059] When the resin material 52 is applied in the second resin application step separated from the first resin application step, when the resin material 52 is applied to the boundary portion between the second inner surface 14b and the circumferential portion 31, air and the like can escape efficiently and the generation of voids and the like is also suppressed. The resin material 52 applied in the second resin application step may protrude toward the second flange 14 by gravity, but since there is no external electrode 40 on the second flange 14 side, there is no influence such as poor connection. Further, since the outer shape of the second flange 14 is within the outer shape of the first flange 12 when viewed in the direction in which the shaft 13 extends, even when the resin material 52 protrudes toward the second flange 14 side, the influence on the outer dimension of the coil component 1 is suppressed.

[0060] FIG. 11 is a diagram showing the second curing step. In the second curing step, for example, the resin material 52 is heated and cured in the heating furnace 60, and the second exterior portion 22 and the exterior portion 20 are formed. Also in the second curing step, the posture in which the shaft 13 is located on the lower side in the gravity direction with respect to the first flange 12 of the magnetic substrate 11 is maintained. That is, the resin material 52 is heated and cured in a posture in which the shaft 13 is located on the lower side in the gravity direction with respect to the first flange 12.

[0061] That is, since the orientation of the magnetic substrate 11 does not change from the liquid resin material 52 until the second exterior portion 22 is formed, the movement of the resin material 52 is suppressed and the formation of the second exterior portion 22 is stabilized. Therefore, the formation of the exterior portion 20 of the coil component 1 is stabilized.

[0062] FIG. 12 is a diagram showing the formation step of the external electrode 40. The external electrode 40 is formed, for example, by providing a solder layer 42 on the base layer 41 shown in FIG. 6. The end of the lead-out portion 32 of the coil conductor 30 is embedded and connected to the solder layer 42, whereby the coil component 1 is completed.

[0063] <Other Embodiments> In the above embodiment, the first exterior portion 21 and the second exterior portion 22 are sequentially formed in the first curing step and the second curing step to form the exterior portion 20. On the other hand, as another embodiment, after the first resin application step and the second resin application step, the exterior portion 20 may be formed in one curing step. In this case, for the resin material 51 applied in the first resin application step, heat is applied at a temperature lower than the heating temperature when forming the exterior portion 20 to remove the solvent, and it is desirable that it be used as a precursor of the first exterior portion 21.

[0064] In the above embodiment, the exterior portion 20 is formed in two steps of forming the first exterior portion 21 and forming the second exterior portion 22. As another embodiment, however, the exterior portion 20 may be formed in three or more steps. In the above embodiment, the resin materials 51 and 52 are applied separately in the first resin application step and the second resin application step. On the other hand, as another embodiment, the resin material may be first applied around the circumferential portion 31 in contact with the first inner surface 12a in the upward direction of the gravity direction, and then, for example, continuously applied in a spiral shape to the lower second inner surface 14a.

[0065] In the above embodiment, the magnetic substrate 11 of the drum core is used as an example. On the other hand, as another embodiment, the magnetic substrate 111 of the T-core shown in FIGS. 3 and 4 may be used. When the magnetic substrate 111 of the T-core is used, in the first resin application step and the second resin application step, the resin materials 51 and 52 are applied so as to be within the outer shape of the first flange 12 when viewed in the direction in which the shaft 13 extends.

Description of Reference Numerals

[0066] 1, 101 Coil Component 2 Circuit Board 2a Substrate 3 Lands 11, 111 Magnetic substrate 12 First flange 12a Outer surface of the first flange (first outer surface) 12b Inner surface of the first flange (first inner surface) 14 Second flange 14a Outer surface of the second flange (second outer surface) 14b Inner surface of the second flange (second inner surface) 20 Exterior part 21 First exterior part 22 Second exterior part 30 Coil conductor 31 Circumferential part 32 Lead-out part 40 External electrode 51, 52 Resin material

Claims

1. A magnetic substrate having a shaft and a first flange that extends in a direction intersecting the axial direction in which the shaft extends and contacts the first end of the shaft, A coil conductor having a circumferential portion formed from a conducting wire around the shaft and a lead-out portion from which the conducting wire is led out to the first flange, An external electrode provided on a part of the outer surface of the first flange to which the end of the lead-out portion is connected, An exterior portion made of a resin material around the circumferential portion, A method for manufacturing a coil component comprising: An application step of applying a liquid resin material around the circumferential portion so as to contact the first flange in a posture where the shaft is positioned below the first flange, A curing step of curing the resin material, A method for manufacturing a coil component, characterized by comprising the above.

2. The method for manufacturing a coil component according to claim 1, wherein the external electrode is provided on the outer surface of the first flange on the side opposite to the inner surface that contacts the first end.

3. The magnetic substrate further has a second flange that extends in a direction intersecting the axial direction and contacts the second end of the shaft opposite to the first end of the shaft, The application step is characterized in that a resin material is provided in a space sandwiched between the first flange and the second flange, extending from the first flange toward the second flange. The method for manufacturing a coil component according to claim 1.

4. The method for manufacturing a coil component according to claim 3, wherein the outer shape of the second flange as viewed in the axial direction fits within the outer shape of the first flange.

5. The curing step is characterized by heating and curing the resin material in a posture where the shaft is positioned below the first flange with respect to the first flange. The method for manufacturing a coil component according to claim 1.

6. The method for manufacturing a coil component according to claim 1, wherein the total length of the magnetic substrate in the axial direction is 2 mm or less.

7. The method for manufacturing a coil component according to claim 1, wherein the length of the shaft exceeds 80% of the total length in the axial direction of the magnetic substrate.

8. The resin material contains a thermosetting resin component, The coil component has a weight change of less than 1% when placed in an environment of 180 °C for 1 hour. The method for manufacturing a coil component according to claim 1.

9. The application step is: A first application step of applying a liquid first resin material so as to contact the first flange, A second coating step of applying a liquid second resin material so as to be in contact with the resin material on the lower side in the gravitational direction with respect to the liquid first resin material or the cured first resin material; The method for manufacturing a coil component according to claim 1, comprising the above.

10. The curing step includes: A first curing step of curing the first resin material applied in the first coating step before the second coating step; A second curing step of curing the second resin material applied in the second coating step; The method for manufacturing a coil component according to claim 9, comprising the above.

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