Coil component, electronic device, and method for manufacturing coil component

Abstract

To provide a coil component that enables miniaturization of engraving while ensuring good readability of engraving.SOLUTION: A coil component includes a coil conductor, a base portion 10 on which the coil conductor is provided, and a marking 40 provided on a flat surface 15 of the base portion 10. The marking 40 is formed by a concave portion 41 recessed inside the base portion 10 with respect to the flat surface 15 and a convex portion 42 protruding outward from the base portion 10 with respect to the flat surface 15.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Coil components are often marked on their surfaces to indicate the orientation of the windings of the coil conductor, the specifications of the coil component, and so on. Recently, more component information has also been recorded, which requires finer marking than ever before. Markings take various forms depending on the application, and various corresponding marking methods are known. For example, Patent Documents 1 and 2 propose methods for marking ceramic materials. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-144630 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-66299 Summary of the Invention [Problem to be solved by the invention]

[0004] Markings on electronic components can become blurred or disappear due to factors such as the environment in which they are used. To prevent this, methods are sometimes used in which the markings are engraved directly onto the surface of coil components. In this case, methods are used in which the markings are made deeper and larger in area to enable fast and reliable image recognition of the markings. However, in order to include more information in the markings, markings are becoming increasingly finer, and the finer the markings, the shallower the marking depth tends to be.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has an object to enable finer markings while ensuring good readability of the markings. [Means for solving the problem]

[0006] The present invention provides a coil conductor, a base portion on which the coil conductor is provided, and a marking provided on a flat surface of the base portion, wherein the marking is formed by a recess recessed inward of the base portion relative to the flat surface and a protrusion protruding outward of the base portion relative to the flat surface, the marking being formed by one recess, the protrusion surrounding the one recess, and the protrusion continuously surrounding the one recess. Within minutes a coil component in which there is no flat portion at the same height as the plane, and the sum of the depth of the recess from the plane and the height of the protrusion from the plane is equal to or greater than the distance between the maximum height portions of the protrusions sandwiching the recess in a direction parallel to the plane.

[0007] In the above configuration, the convex portion may be formed from the same material as the base portion.

[0008] In the above configuration, the inner surface of the recess and the inner surface of the protrusion may be configured to be continuous surfaces.

[0009] In the above configuration, the depth of the recess from the plane may be equal to or less than the width of the recess.

[0011] In the above configuration, the base portion may be a sintered body of an inorganic material, or may contain particles of a plurality of inorganic materials, or may contain particles of a plurality of inorganic materials and a resin.

[0012] In the above configuration, the marking may be a two-dimensional code.

[0013] The present invention provides an electronic device including the coil component described above and a circuit board on which the coil component is mounted.

[0014] The present invention provides a method for manufacturing a coil conductor, comprising the steps of: preparing a base on which a coil conductor is provided; and forming, on a flat surface of the base, using a laser or a thermal heater, a marking having a recess recessed inward from the flat surface of the base and a protrusion protruding outward from the flat surface of the base; the marking is made up of one of the recesses, the protrusion surrounding the recess, and the protrusion continuously surrounding the recess. Within minutes a coil component manufacturing method in which there is no flat portion at the same height as the plane, and the sum of the depth of the recess from the plane and the height of the protrusion from the plane is equal to or greater than the distance between the maximum height parts of the protrusions sandwiching the recess in a direction parallel to the plane. [Effects of the Invention]

[0015] According to the present invention, the markings can be made finer while ensuring good readability of the markings. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view showing a coil component according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective view showing the coil component according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view of a portion of the marking. [Figure 4] FIG. 4 is a cross-sectional view showing a case where automatic recognition is performed on the marking by image. [Figure 5] 5(a) and 5(b) are cross-sectional views showing a first method for forming the marking. [Figure 6] 6(a) and 6(b) are cross-sectional views showing a second method for forming the marking. [Figure 7] FIG. 7 is a cross-sectional view showing markings formed on a coil component according to a comparative example. [Figure 8] FIG. 8 is a perspective view showing an electronic device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. However, the present invention is not limited to the illustrated embodiments. Furthermore, components common to multiple drawings are designated by the same reference numerals throughout the multiple drawings. Please note that the drawings are not necessarily drawn to scale for the sake of convenience.

[0018] [First embodiment] Fig. 1 is a perspective view showing a coil component according to a first embodiment of the present invention. Fig. 2 is an exploded perspective view showing a coil component according to the first embodiment of the present invention. For convenience of illustration, external electrodes 50, 51 are omitted from Fig. 2. Figs. 1 and 2 show an example in which the coil component is a laminated inductor, but the present invention is not limited to this and other coil components may also be used.

[0019] 1 and 2, the coil device 100 includes a base portion 10, a coil conductor 30 built into the base portion 10, external electrodes 50 and 51 provided on a portion of the surface of the base portion 10, and a marking 40 provided on a portion of the surface of the base portion 10. The base portion 10 has at least one flat surface and is formed in a generally rectangular parallelepiped shape. The size of the coil device 10 is determined by the size of the base portion 10, and the "length", "width", and "thickness" directions of the base portion 10 are illustrated as "L", "W", and "T", respectively. The coil device 100 has, for example, a length dimension (L direction dimension) of 0.2 mm to 10.0 mm, a width dimension (W direction dimension) of 0.1 mm to 10.0 mm, and a thickness dimension (T direction dimension) of 0.1 mm to 10.0 mm. The base portion 10 has dimensions roughly equivalent to those of the coil component excluding the external electrodes, and is similar to the dimensions of the coil component.

[0020] The base 10 is formed of insulating layers 20-26 and conductive patterns 31-35. The insulating layers 20-26 contain an inorganic material. Examples of inorganic materials include ferrite, which is a magnetic material. They may also be non-magnetic ceramics, sintered inorganic materials, materials made by solidifying particles of multiple inorganic materials, or materials made from particles of multiple inorganic materials and resin. For example, the base 10 may contain one type of inorganic material, such as ceramic, zirconia or alumina, or two types of inorganic materials, such as metal magnetic particles primarily composed of iron and glass, or may contain one type of inorganic material, such as metal magnetic particles and resin, and one type of organic material.

[0021] Conductive patterns 31 to 35 formed on insulating layers 21 to 25 are electrically connected to conductor patterns formed on adjacent magnetic layers through vias V1 to V4 included in conductor patterns 32 to 35, thereby forming coil conductor 30. Coil conductor 30 has a coil axis 36. Coil conductor 30 is formed by winding conductor patterns 31 to 35 around coil axis 36 and is built into base portion 10, one end of conductor pattern 31 is electrically connected to external electrode 50, and one end of conductor pattern 35 is electrically connected to external electrode 51. Conductive patterns 31 to 35 are formed containing a metal with high conductivity, such as silver (Ag), palladium (Pd), copper (Cu), aluminum (Al), or an alloy thereof.

[0022] The markings 40 provided on the surface of the base portion 10 are adjusted in number to record information such as the specifications of the coil device 100, and multiple markings 40 are provided depending on the amount of information. An example of providing multiple markings 40 is a two-dimensional code. To create a two-dimensional code, the markings 40 are arranged vertically and horizontally, and multiple markings 40 are grouped together. In this case, the size of the group is, for example, 0.3 mm to 1.6 mm vertically and 0.3 mm to 1.6 mm horizontally. However, the markings 40 are not limited to two-dimensional codes and may be other types such as numbers and / or letters. For example, the markings 40 are provided on the upper surface 12, which is opposite the lower surface 11 of the base portion 10, which is the mounting surface.

[0023] FIG. 3 is a cross-sectional view of a portion of the marking. Referring to FIG. 3, the marking 40 is formed of a recess 41 and a protrusion 42 in a portion of the flat surface 15 of the base portion 10. In a cross section of the flat surface 15 viewed horizontally, the marking 40 has a recess 41 extending inward from the flat surface 15 and a protrusion 42 extending outward from the flat surface 15. In addition, in a cross section of the flat surface 15 viewed vertically, the marking 40 is formed such that one recess 41 is surrounded by one protrusion 42. The protrusion 42 is formed continuously around one recess 41. In a cross section of the marking 40 viewed horizontally, the inner surfaces of the recess 41 and the protrusion 42 form a continuous surface. In other words, the marking 40 has a protrusion 42, a recess 41, and another protrusion 42 formed side by side. In addition, the inner surfaces of the protrusion 42 and the recess 41 are continuous surfaces and are connected by several curved surfaces.

[0024] The flat surface 15 is at least a part of the upper surface 12 of the base part 10. When viewed vertically, the flat surface 15 has an area larger than the area occupied by the markings 40. The arithmetic mean roughness Ra of the flat surface 15 excluding the markings 40 is 0.2 or less. When the direction parallel to the flat surface 15 is the "H" direction and the direction perpendicular to the flat surface 15 is the "V" direction, in a cross section viewed horizontally through the flat surface 15, the recesses 41 are recessed in the negative direction from the flat surface 15 of the base part 10, and the average depth of the recesses 41 from the flat surface 15 is a depth of -D. The protrusions 42 protrude in the positive direction from the flat surface 15 of the base part 10, and the average height of the protrusions 42 from the flat surface 15 is a height of +Y. When viewed horizontally through the flat surface 15 of the markings 40, the width X of the recesses 41 is greater than or equal to the depth D of the recesses 41. Furthermore, the distance Z between the two protrusions 42 that sandwich one recess 41 is determined by the length of a line segment obtained by connecting the maximum height parts of each protrusion 42 in a line parallel to the plane 15. The combined size of the depth D of the recess 41 and the height Y of the protrusion 42 is equal to or greater than the distance Z between the two protrusions 42. This ensures that the combined size of the depth D of the recess 41 and the height Y of the protrusion 42 is maintained even if the distance Z between the two protrusions 42, i.e., the size of the marking 40, is reduced.

[0025] The width X of the recess 41 is, for example, 30 μm to 90 μm. Alternatively, the width X may be 30 μm to 70 μm. The depth D of the recess 41 is, for example, 30 μm to 80 μm. Alternatively, the depth D may be 20 μm to 60 μm. The height Y of the protrusion 42 is, for example, 20 μm to 50 μm. Alternatively, the height Y may be 20 μm to 40 μm. The combined size of the depth D of the recess 41 and the height Y of the protrusion 42 is, for example, 50 μm to 130 μm. Alternatively, this combined size may be 50 μm to 100 μm. The distance Z between the two protrusions 42 sandwiching one recess 41 is, for example, 40 μm to 100 μm. Alternatively, the distance Z may be 40 μm to 80 μm.

[0026] The marking 40 is formed using a laser or a thermal heater. The protrusions 42 of the marking 40 are formed by melting a portion of the base 10 at the position where the recess 41 will be formed, and then forming the recess 41, with the molten material rising on both sides of the recess 41. By forming the recess 41 and the protrusions 42 in this manner by melting, the protrusions 42 contain the same inorganic material as the base 10 and can be formed integrally with the base 10. The protrusions 42 are also formed by melting the recess 41 and solidifying the molten material as the protrusions 42. By performing this melting and solidification simultaneously, the inner surfaces of the protrusions 42 and the recess 41 form a continuous surface. The protrusions 42 are located on both sides of the recess 41, and the inner surfaces of the inner recesses 41 and the inner surfaces of the inner protrusions 42 form a continuous surface. In other words, the marking 40 is formed by forming the protrusions 42, the recesses 41, and the protrusions 42 side by side, and the inner surfaces of the inner recesses 41 and the inner protrusions 42 form a continuous surface.

[0027] [Readable engraving] FIG. 4 is a cross-sectional view showing automatic image-based recognition of the marking 40. Referring to FIG. 4, when illumination light 80 is shone on the marking 40, reflection from the flat surface 15 is normally directed in a direction perpendicular to the flat surface 15, which is recognized by the camera as a bright area. In contrast, between two convex portions 42 on the inside of the marking 40, reflection is directed in irregular directions, and this area is recognized as a dark area. The marking 40 is recognized by the contrast between the bright and dark areas. The deeper and narrower the marking 40, the less the illumination light 80 is reflected, so the greater the contrast between light and dark, making the marking 40 easier to recognize. Multiple markings 40 are arranged, and by recognizing their positions, the necessary information can be read.

[0028] [Manufacturing method] An example of a manufacturing method for a coil component according to the first embodiment will be described. First, a paste containing ferrite powder is applied to a film such as a polyethylene terephthalate (PET) film, and then dried in a dryer such as a hot air dryer to form a magnetic film. If necessary, through holes are formed in predetermined positions in the magnetic film using, for example, a laser. A conductive paste such as silver paste or copper paste is applied to the magnetic film by a printing method such as screen printing, and then dried in a dryer such as a hot air dryer to form a precursor for the conductive pattern. A paste containing ferrite powder is applied to the magnetic film by a printing method such as screen printing, and then dried in a dryer to form a magnetic film around the conductive pattern. The film is then peeled off. This forms a magnetic layer provided with a conductive pattern.

[0029] A paste containing ferrite powder is applied onto a film such as a PET film by, for example, a doctor blade method, and then dried in a dryer to form a magnetic film, after which the film is peeled off, resulting in a magnetic layer without a conductive pattern.

[0030] The magnetic layers are stacked in a predetermined order and compressed. The compressed magnetic layers are cut into chip units and then fired by heat treatment at a predetermined temperature. This results in the stacking of insulating layers 20-26, forming a base 10 incorporating a coil conductor 30 formed by conductor patterns 31-35. Then, external electrodes 50, 51 are formed on the surface of the base 10 by a method used in thin film processes, such as paste printing, plating, or sputtering.

[0031] Next, an inscription 40 is formed on the upper surface 12 of the base part 10. A first method for forming an inscription is to use a laser, and FIGS. 5(a) and (b) are cross-sectional views showing this method. Referring to FIG. 5(a), a laser light source 60 irradiates a flat surface 15 of the base part 10 with laser light 61 to melt the base part 10. At this time, in order to form the inscription 40 consisting of recesses 41 and protrusions 42, the power and / or irradiation time of the laser light 61 are controlled so that the temperature of the parts of the base part 10 irradiated with the laser light 61 is equal to or higher than the melting temperature of the material of the base part 10 but is not so high that the material of the base part 10 sublimes. As a result, as shown in FIG. 5(b), recesses 41 are formed at the parts irradiated with the laser light 61, and the material melted by the laser light 61 rises on the surface of the base part 10 to form protrusions 42. Thus, the inscription 40 consisting of the recesses 41 and protrusions 42 is formed. The width of the recesses 41 is controlled by adjusting the spot diameter of the laser light 61 irradiated onto the base portion 10, and the depth of the recesses 41 is controlled by adjusting the amount of energy.

[0032] A second method for forming the marking is to contact a heat source, and Figures 6(a) and (b) are cross-sectional views showing this method. Referring to Figures 6(a) and 6(b), a thermal heater source 62 may be used instead of the laser light source 60. In this case, too, the thermal heater source 62 is pressed against the base part 10 as shown by arrow 63 to apply heat so that the temperature is equal to or higher than the melting temperature of the material of the base part 10 but does not sublimate the material of the base part 10, thereby forming the marking 40 consisting of the recessed parts 41 and the protruding parts 42.

[0033] [Comparative form] Fig. 7 is a cross-sectional view showing markings formed on a coil component according to a comparative example. Referring to Fig. 7, in the comparative example, markings 340 are formed by recesses 341 recessed inward of base portion 310 relative to flat surface 315 of base portion 310. In other words, no protrusions protruding outward from flat surface 315 of base portion 310 are formed.

[0034] In the comparative example, to improve the readability of the marking 340, the recess 341 is deepened to increase the contrast between light and dark. To deepen the recess 341, the energy applied to the base 310 by the laser light irradiated onto the base 310 from the laser light source is increased. Therefore, increasing the energy increases the width of the recess 341, making it difficult to form a fine marking 340. Furthermore, increasing the energy may cause damage such as deterioration to the base 310 and adversely affect other components such as the coil conductor. Furthermore, the depth and width of the recess 341 increase the volume of the recess 341. Therefore, when the marking 340 is formed, a large amount of dust is scattered from the base 310, which may cause contamination around the marking 340 due to the adhesion of dust.

[0035] On the other hand, according to the first embodiment, the marking 40 is formed by recesses 41 and protrusions 42. Therefore, the depth of the marking 40 is the sum of the depth of the recesses 41 and the height of the protrusions 42, so the contrast between light and dark is increased without making the recesses 41 deep, and the readability of the marking 40 can be improved. Because the recesses 41 do not need to be deep, the width of the recesses 41 can be prevented from increasing. This allows the marking 40 to be made finer.

[0036] Furthermore, according to the first embodiment, the marking 40 having the recessed portion 41 and the protruding portion 42 is formed on the flat surface 15 of the base portion 10 using a laser or a thermal heater. Forming the marking 40 with the recessed portion 41 and the protruding portion 42 improves the readability of the marking 40 and enables the marking 40 to be made finer. Furthermore, the recessed portion 41 does not need to be deep, and the energy required to form the recessed portion 41 is kept low, thereby suppressing damage to the base portion 10, such as deterioration, and adverse effects on other components, such as the coil conductor 30. Furthermore, when the recessed portion 41 is formed by melting the base portion 10, the protruding portion 42 is formed from the material that formed the recessed portion 41, thereby suppressing the scattering of dust and the adhesion of dust to the base portion 10 and resulting in contamination. When the marking 40 is formed using the laser beam 61, the energy of the laser beam 61 is applied to the base portion 10 instantaneously, effectively suppressing damage to the base portion 10. When the marking 40 is formed using the heater source 62, the temperature can be easily adjusted to match the material of the base portion 10.

[0037] The protrusions 42, which are part of the marking 40, are formed from the same inorganic material as the base portion 10. The protrusions 42 are formed from the molten material of the recesses 41, and therefore contain the same inorganic material and the same components as the base portion 10. The amounts of components in the protrusions 42 and the base portion 10 may differ. Furthermore, by integrating the protrusions 42 and the base portion 10 with substantially the same material, the marking 40 and the base portion 10 will experience similar thermal contraction even if the coil component 100 is placed in an environment with large temperature changes, and damage and the like can be suppressed. Furthermore, because the marking 40 is made from an inorganic material, it is highly resistant and deterioration of the marking 40 can be suppressed.

[0038] The marking 40 has a continuous surface where the inner surface of the recessed portion 41 and the inner surface of the protruding portion 42 are continuous. This reduces the area required to form the marking 40. In other words, the marking 40 can be made both fine and legible.

[0039] The depth D of the recess 41 from the flat surface 15 of the base portion 10 is preferably equal to or less than the width X of the recess 41. This reduces the amount of processing required for the recess 41, reduces the energy applied to the base portion 10, and suppresses damage to the base portion 10 and adverse effects on other components such as the coil conductor 30. From this perspective, the depth D of the recess 41 is preferably equal to or less than 0.9 times the width X of the recess 41, more preferably equal to or less than 0.8 times, and still more preferably equal to or less than 0.7 times. The width X of the recess 41 is the distance connecting the two points where an extension of the flat surface 15 intersects with the inner surface of the recess 41.

[0040] The sum of the depth D of the recess 41 and the height Y of the protrusion 42 is equal to or greater than the distance Z between the two protrusions 42. This allows the marking 40 to be made finer while still ensuring the readability of the marking 40. From this perspective, the sum of the depth D of the recess 41 and the height Y of the protrusion 42 is preferably 1.25 times or more, more preferably 1.5 times or more, and even more preferably 2.0 times or more, the distance Z between the two protrusions 42.

[0041] The base 10 may be a sintered body of an inorganic material, or may contain particles of multiple inorganic materials, or may contain particles of multiple inorganic materials and a resin. A highly readable marking 40 that can be finely detailed can be formed on such a base 10. Furthermore, damage to the base 10 can be suppressed.

[0042] The markings 40 may be numbers or letters, but may also be two-dimensional codes that can contain a large amount of information because they can be made finer as described above.

[0043] The marking 40 may be provided on the upper surface 12 of the base portion 10, which is opposite to the lower surface 11 that is the mounting surface. This allows the marking 40 to be used as a direction identification marker for identifying the direction of the coil component 100.

[0044] In the first embodiment, a coil component having a coil conductor 30 built into the base portion 10 is shown as an example, but the coil component may be any of laminated, wound, thin film, etc., such as a coil component having a coil conductor 30 wound around the surface of the base portion 10.

[0045] [Second embodiment] Fig. 8 is a perspective view showing an electronic device according to a second embodiment of the present invention. In Fig. 8, solder 72 is hatched for clarity. Referring to Fig. 8, electronic device 200 includes circuit board 70 and coil component 100 mounted on circuit board 70. Coil component 100 is mounted on circuit board 70 by joining external electrodes 50, 51 to electrodes 71 of circuit board 70 with solder 72. This results in electronic device 200 including coil component 100 having highly readable and fine markings 40. [Example]

[0046] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the embodiments described in these examples.

[0047] [Example] An inscription was formed on the flat surface of a base made of ferrite material. A laser beam with a wavelength of 1064 nm was used to form the inscription, with the laser beam irradiation power set to 5 W to 10 W and the irradiation time set to 0.05 seconds or less. This resulted in the formation of an inscription 40 having recesses and protrusions. The recesses had a depth D of 30 μm to 40 μm and a width X of 40 μm to 50 μm, with the recess depth D being smaller than the width X of the recess. The height Y of the protrusions was 20 μm to 30 μm, and the spacing Z between the two protrusions sandwiching one recess was 40 μm to 50 μm, with the sum of the recess depth D and the protrusion height Y being equal to or greater than the spacing Z between the two protrusions. The recess depth D was 100 μm or less, the recess width X was 100 μm or less, and the spacing Z between the two protrusions was 100 μm or less, but the inscription was easily readable. Furthermore, the depth D of the recessed portion can be 50 μm or less, the width X of the recessed portion can be 50 μm or less, and the distance Z between two raised portions can be 50 μm or less, thereby forming a fine marking.

[0048] The above laser light conditions are an example when the base is made of ferrite material, and are changed as appropriate depending on the material of the base. Furthermore, in order to make the markings finer and to prevent damage to the base, such as deterioration and discoloration, it is preferable that the laser light be irradiated to the same location on the base for a short time and the number of times is small. It is preferable that the laser light be irradiated to the same location on the base only once.

[0049] [Comparative Example] An inscription was formed on the flat surface of a base part made of ferrite material. A laser beam with a wavelength of 1064 nm was used to form the inscription, with the laser beam irradiation output set to 30 W or more and the irradiation time set to 0.1 seconds or more. This resulted in an inscription consisting of recesses and no protrusions. The depth D of the recesses was 140 μm to 150 μm, and the width X of the recesses 141 was 120 μm to 130 μm. The inscription was easy to read, but was too wide to be finely sized.

[0050] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0051] 10 Base 11 Bottom side 12 Top side 15 plane 20~26 Insulation layer 30 Coil conductor 31~35 Conductor pattern 36 Coil shaft 40 Engraving 41 Recess 42 Convex part 50, 51 External electrode 60 laser light source 61 Laser light 62 Heat source 70 Circuit Board 71 Electrode 72 Solder 80 Illumination 100 Coil parts 200 Electronic equipment 310 Base 315 plane 340 Engraving 341 recess

Claims

1. A coil conductor; a base portion on which the coil conductor is provided; a marking provided on the flat surface of the base portion; the marking is formed by a recess recessed inward from the flat surface of the base portion and a protrusion protruding outward from the flat surface of the base portion, the marking consists of one recess, the protrusion surrounds the recess, and there is no flat portion at the same height as the flat surface within a portion where the protrusion continuously surrounds the recess, a sum of the depth of the recess from the plane and the height of the protrusion from the plane is equal to or greater than the distance between the recess and the protrusion at their maximum heights in a direction parallel to the plane.

2. The coil component according to claim 1 , wherein the protrusions are formed from the same material as the base portion.

3. The coil component according to claim 1 or 2, wherein the inner surface of the recess and the inner surface of the protrusion form a continuous surface.

4. The coil component according to claim 1 , wherein the depth of the recess from the plane is equal to or less than the width of the recess.

5. The coil component according to claim 1 , wherein the base portion is a sintered body of an inorganic material, or contains particles of a plurality of inorganic materials, or contains particles of a plurality of inorganic materials and a resin.

6. The coil component according to claim 1 , wherein the marking is a two-dimensional code.

7. The coil component according to any one of claims 1 to 6; and a circuit board on which the coil component is mounted.

8. providing a base portion on which a coil conductor is provided; and forming an inscription on the flat surface of the base portion using a laser or a thermal heater, the inscription having a recess recessed inward from the flat surface of the base portion and a protrusion protruding outward from the flat surface of the base portion, the marking is made up of one recess, the recess is surrounded by the protrusion, and there is no flat portion at the same height as the flat surface within a portion where the protrusion continuously surrounds the recess, a sum of the depth of the recess from the plane and the height of the protrusion from the plane is equal to or greater than the distance between the recess and the protrusion at their maximum heights in a direction parallel to the plane.

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