Coil component and method of manufacturing the same

Disclosed herein is a coil component that includes: a magnetic element body containing magnetic powder, the magnetic element body having first and second surfaces; a coil conductor embedded in the magnetic element body; and an external terminal connected to the coil conductor and exposed on the first surface of the magnetic element body. The second surface of the magnetic element body is free from the external terminal. The first surface is greater in surface roughness than the second surface.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a coil component and its manufacturing method and, more particularly, to a coil component having a structure in which a coil conductor is embedded in a magnetic element body containing magnetic powder and its manufacturing method.

Description of Related Art

A common surface-mount type coil component has a configuration in which a coil conductor is formed on the surface of a non-magnetic resin layer. In order to enhance inductance, the coil conductor may be embedded in a magnetic material. For example, JP 2013-225718 A discloses a coil component having a configuration in which a resin substrate on which a coil conductor is formed is embedded in magnetic resin. The magnetic resin is a mixture of metal magnetic powder and a resin material and has high permeability and thus functions as a magnetic path for magnetic flux generated from the coil conductor.

However, in the coil component described in JP 2013-225718 A, an external terminal is formed over the side surface of a chip and main surface thereof perpendicular to a coil axis, so that magnetic flux is partially blocked by the external terminal, which may result in reduction in inductance. To prevent this, the external terminal may be formed only on the chip side surface; however, even in this case, when the coil component is mounted on a circuit board, solder may sneak along the surface of the magnetic resin, with the result that an unintended portion may be covered with the solder.

SUMMARY

It is therefore an object of the present invention to provide a coil component capable of preventing sneaking of solder at mounting and its manufacturing method.

A coil component according to the present invention includes a magnetic element body containing magnetic powder, a coil conductor embedded in the magnetic element body, and an external terminal connected to the coil conductor and exposed on a first surface of the magnetic element body. The magnetic element body further includes a second surface on which the external terminal is not exposed. The surface roughness of the first surface is larger than the surface roughness of the second surface.

According to the present invention, the surface roughness of the first surface of the magnetic element body is large, so that the creeping distance of the first surface is increased. This makes it difficult for solder to sneak along the first surface at mounting, preventing the solder from covering an unintended portion of the magnetic element body.

In the present invention, the magnetic element body may have a substantially rectangular parallelepiped shape. The first and second surfaces may be perpendicular to each other. The magnetic element body may further include a third surface positioned on the side opposite to the first surface, a fourth surface positioned on the side opposite to the second surface, and fifth and sixth surfaces which are perpendicular to the first to fourth surfaces and positioned on mutually opposite sides. The external terminal may include a first external terminal connected to one end of the coil conductor and a second external terminal connected to the other end of the coil conductor. The first external terminal may be exposed on the first and fifth surfaces without being exposed on the second, third, fourth, and sixth surfaces. The second external terminal may be exposed on the first and sixth surfaces without being exposed on the second, third, fourth, and fifth surfaces. With this configuration, the first and second external terminals are each formed over the two surfaces, so that when the coil component is mounted on a circuit board by soldering, a fillet of the solder can be formed.

In the present invention, the dimension of each of the first and second terminal electrodes in a direction perpendicular to the second and fourth surfaces may be smaller than the dimension of the magnetic element body in the same direction. This makes it difficult for the solder formed in the first and second external terminals to sneak to the second and fourth surfaces.

In the present invention, the coil axis of the coil conductor may be perpendicular to the second and fourth surfaces. This prevents magnetic flux passing through the second and fourth surfaces from being blocked by the solder sneaking to the second and fourth surfaces.

In the present invention, the magnetic powder is made of a metal magnetic material whose surface is insulation-coated. This prevents the metal magnetic material from being exposed even when the surface of the magnetic powder is exposed from the magnetic element body.

In the present invention, the coil conductor may be made of copper (Cu), and the external terminal may contain nickel (Ni) and tin (Su). This can enhance solder wettability.

A coil component manufacturing method according to the present invention includes the steps of embedding a coil conductor in a magnetic element body containing magnetic powder, dicing the magnetic element body so as to expose the end portion of the coil conductor, and etching a magnetic body exposed on the dicing surface of the magnetic element body.

According to the present invention, the magnetic body exposed on the dicing surface of the magnetic element body is removed, making it possible to increase the surface roughness of the dicing surface of the magnetic element body.

The coil component manufacturing method according to the present invention may further include a step of plating the end portion of the coil conductor exposed on the dicing surface after etching of the magnetic body. Thus, the plating is performed after removal of the magnetic body exposed on the dicing surface, preventing plating from being formed on the surface of the magnetic body.

As describe above, according to the present invention, in the coil component using the magnetic element body containing the magnetic powder, it is possible to prevent sneaking of solder at mounting.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1is a schematic perspective view illustrating the outer appearance of a coil component1according to a preferred embodiment of the present invention.

The coil component1according to the present embodiment is a surface-mount type chip component suitably used as an inductor for a power supply circuit and includes a magnetic element body10constituted of first and second magnetic material layers11and12and a coil part20sandwiched between the magnetic material layers11and12, as illustrated inFIG. 1. In the present embodiment, the coil part20has a configuration in which four conductive layers each having a coil conductive pattern are laminated to form one coil conductor. One end of the coil conductor is connected to a first external terminal E1, and the other end thereof is connected to a second external terminal E2.

Detailed configuration of the coil part20will be described later.

The magnetic element body10constituted of the magnetic material layers11and12is a composite member formed from resin containing metal magnetic powder made of iron (Fe) or a permalloy-based material and constitutes a magnetic path for magnetic flux which is generated when current is made to flow in the coil. As the resin, epoxy resin of liquid or powder is preferably used.

Unlike a common laminated coil component, the coil component1according to the present embodiment is vertically mounted such that the z-direction that is the lamination direction is parallel to a circuit board. Specifically, a surface S1of the magnetic element body10that constitutes the xz plane is used as a mounting surface. On the mounting surface S1, the first and second external terminals E1and E2are provided. The first external terminal E1is connected with one end of the coil conductor formed in the coil part20, and the second external terminal E2is connected with the other end of the coil conductor formed in the coil part20.

As illustrated inFIG. 1, the first external terminal E1is continuously formed from the surface S1to a surface S5constituting the yz plane, and the second external terminal E2is continuously formed from the surface S1to a side surface S6constituting the yz plane. Although details will be described later, the external terminals E1and E2are each constituted of a laminated film of nickel (Ni) and tin (Sn) formed on the exposed surface of an electrode pattern included in the coil part20. The external terminals E1and E2are not formed on the other surfaces of the magnetic element body10, i.e., surfaces S2and S4constituting the xy plane and the surface S3constituting the xz plane.

A dimension W2of the external terminals E1and E2in the z-direction is smaller than a dimension W1of the magnetic element body10in the z-direction. Thus, the surfaces S1and S5or S6of the magnetic element body10are exposed on both sides of the external terminal E1or E2in the z-direction.

FIG. 2is a side view illustrating a state where the coil component1according to the present embodiment is mounted on a circuit board80as viewed in the lamination direction.

As illustrated inFIG. 2, the coil component1according to the present embodiment is mounted vertically on the circuit board80. Specifically, the coil component is mounted such that the surface S1of the magnetic element body10faces the mounting surface of the circuit board80. That is, the z-direction, the lamination direction of the coil component1, is in parallel to the mounting surface of the circuit board80.

The circuit board80has land patterns81and82, which are connected with the external terminals E1and E2of the coil component1, respectively. The electrical/mechanical connection between the land patterns81,82and external terminals E1, E2is achieved by solder83. A fillet of the solder83is formed on a part of the external terminal E1(E2) that is formed on the surface S5(S6). The external terminals E1and E2are each constituted of a laminated film of nickel (Ni) and tin (Sn), whereby wettability of the solder is enhanced.

FIG. 3is a cross-sectional view of the coil component1according to the present embodiment.

As illustrated inFIG. 3, the coil part20included in the coil component1is sandwiched between the two magnetic material layers11and12and has a configuration in which interlayer insulating layers40to44and conductive layers31to34are alternately laminated. The conductive layers31to34are connected to one another through holes formed in the interlayer insulating layers41to43, respectively to thereby form a coil. As the material of the conductive layers31to34, copper (Cu) is preferably used. A magnetic member13made of the same material as the magnetic material layer12is embedded in the inner diameter part of the coil. The magnetic member13also constitutes a part of the magnetic element body10together with the magnetic material layers11and12. The interlayer insulating layers40to44are each made of, e.g., resin, and a non-magnetic material is used for at least the interlayer insulating layers41to43. A magnetic material may be used for the lowermost interlayer insulating layer40and the uppermost interlayer insulating layer44.

The conductive layer31is the first conductive layer formed on the upper surface of the magnetic material layer through the interlayer insulating layer40. The conductive layer31has a coil conductive pattern C1spirally wound in two turns and two electrode patterns51and61. The electrode pattern51is connected to one end of the coil conductive pattern C1, while the electrode pattern61is formed independently of the coil conductive pattern C1. The electrode pattern51is exposed from the coil part20, and the external terminal E1is formed on the exposed surface of the electrode pattern51. The electrode pattern61is exposed from the coil part20, and the external terminal E2is formed on the exposed surface of the electrode pattern61.

The conductive layer32is the second conductive layer formed on the upper surface of the conductive layer through the interlayer insulating layer41. The conductive layer32has a coil conductive pattern C2spirally wound in two turns and two electrode patterns52and62. The electrode patterns52and62are both formed independently of the coil conductive pattern C2. The electrode pattern52is exposed from the coil part20, and the external terminal E1is formed on the exposed surface of the electrode pattern52. The electrode pattern62is exposed from the coil part20, and the external terminal E2is formed on the exposed surface of the electrode pattern62.

The conductive layer33is the third conductive layer formed on the upper surface of the conductive layer32through the interlayer insulating layer42. The conductive layer33has a coil conductive pattern C3spirally wound in two turns and two electrode patterns53and63. The electrode patterns53and63are both formed independently of the coil conductive pattern C3. The electrode pattern is exposed from the coil part20, and the external terminal E1is formed on the exposed surface of the electrode pattern53. The electrode pattern63is exposed from the coil part20, and the external terminal E2is formed on the exposed surface of the electrode pattern63.

The conductive layer34is the fourth conductive layer formed on the upper surface of the conductive layer through the interlayer insulating layer43. The conductive layer34has a coil conductive pattern C4spirally wound in two turns and two electrode patterns54and64. The electrode pattern64is connected to one end of the coil conductive pattern C4, while the electrode pattern54is formed independently of the coil conductive pattern C4. The electrode pattern54is exposed from the coil part20, and the external terminal E1is formed on the exposed surface of the electrode pattern54. The electrode pattern64is exposed from the coil part20, and the external terminal E2is formed on the exposed surface of the electrode pattern64.

The coil conductive pattern C1and the coil conductive pattern C2are connected to each other through a via conductor formed penetrating the interlayer insulating layer41, the coil conductive pattern C2and the coil conductive pattern C3are connected to each other through a via conductor formed penetrating the interlayer insulating layer42, and the coil conductive pattern C3and the coil conductive pattern C4are connected to each other through a via conductor formed penetrating the interlayer insulating layer43. As a result, a coil of eight turns is formed by the coil conductive patterns C1to C4, and one and the other ends thereof are connected respectively to the external terminals E1and E2.

Further, the electrode patterns51to54are connected to one another through via conductors V1to V3formed penetrating the interlayer insulating layers41to43. Similarly, the electrode patterns61to64are connected to one another through via conductors V4to V6formed penetrating the interlayer insulating layers41to43. Although not especially limited, the formation positions of the respective via conductors V1to V3as viewed in the lamination direction differ from one another and, similarly, the formation positions of the respective via conductors V4to V6as viewed in the lamination direction differ from one another.

The surfaces of the respective conductive layers32to34may be recessed at portions where the via conductors V1to V6are formed. However, since the formation positions of the via conductors V1to V3as viewed in the lamination direction are offset from one another, and the formation positions of the via conductors V4to V6as viewed in the lamination direction are offset from one another, the recesses formed in the surfaces of the respective conductive layers32to34are not accumulated. Thus, a high degree of flatness can be ensured.

FIG. 4is a schematic cross-sectional view illustrating in an enlarged manner an area D1illustrated inFIG. 3, andFIG. 5is a schematic cross-sectional view illustrating in an enlarged manner an area D2illustrated inFIG. 3. The area D1refers to a cross section including the surface S4of the magnetic element body10, and an area including the surface S2of the magnetic element body10has the same cross section as the area D1. The area D2refers to a cross section including the surface S6of the magnetic element body10, and areas each including surfaces S1, S3, and S5of the magnetic element body10have the same cross section as the D2.

As illustrated inFIGS. 4 and 5, the magnetic element body10is a composite material containing magnetic powder70as a filler and a resin material73such as epoxy resin as a binder. The magnetic powder70is constituted of a body part71of a metal magnetic material made of iron (Fe) or a permalloy-based material and an insulating coat72that covers the surface of the body part71and ensures the insulation property of the magnetic element body10. The insulating coat72is, e.g., silica.

As illustrated inFIG. 4, the surface S4(S2) of the magnetic element body10is substantially entirely composed of the resin material73, and the body part71of the magnetic powder70is not exposed from the surface S4. The magnetic powder70may be partially exposed from the surface S4(S2); however, even in such a case, the metal magnetic material constituting the body part71is not exposed from the surface S4(S2) since the surface of the magnetic powder70is covered with the insulating coat72.

On the other hand, as illustrated inFIG. 5, the surface S6(S1, S3, S5) of the magnetic element body10has many recesses74formed as a result of removal of the body part71of the magnetic powder70. Accordingly, the surface roughness of the surface S6(S1, S3, S5) of the magnetic element body10is significantly larger than the surface roughness of the surface S4(S2) of the magnetic element body10. The surface roughness is determined by the particle diameter of the magnetic powder70as the filler. When the particle diameter of the magnetic powder is 10 μm to 60 μm, the surface roughness Ra of the surface S6(S1, S3, S5) of the magnetic element body10is 5 μm to 50 μm. On the other hand, the surface S4(S2) of the magnetic element body10has no recess74, so that the surface roughness Ra is as small as 1 μm to 5 μm. The inner wall of the recess74is covered with the insulating coat72.

FIG. 6is a schematic side view illustrating in an enlarged manner a portion around the external terminal E1of the coil component1which is mounted on the circuit board80.

As described above, the surface S1of the magnetic element body10on which the external terminal E1is formed has an increased surface roughness due to the existence of the many recesses74. Thus, as compared with the surface roughness being small like the surfaces S2and S4, the creeping distance from the external terminal E1to the surfaces S2and S4is increased, thus making it difficult for the solder83to sneak to the surfaces S2and S4along the surface S1. The surfaces S2and S4are surfaces vertical to the coil axis, so that when current is made to flow in the coil conductor, a large amount of magnetic flux is generated on the surface S2and S4. Thus, when the solder83sneaks to the surfaces S2and S4of the magnetic element body10, the magnetic flux is partially blocked by the solder83, which may result in reduction in inductance. On the other hand, in the coil component1according to the present embodiment, the surface roughness of the surfaces S1, S5, and S6on which the external terminal (E1, E2) is formed is made larger than the surface roughness of the surfaces S2and S4, so that it is possible to prevent the solder83from sneaking to the surfaces S2and S4to thereby prevent reduction in inductance.

The following describes a manufacturing method for the coil component1according to the present embodiment.

FIGS. 7A to 7F and 8A to 8Dare process views for explaining the manufacturing processes of the coil component1according to the present embodiment.FIGS. 9A to 9Hare plan views for explaining a pattern shape in each process.

As illustrated inFIG. 7A, a support substrate S having a predetermined level of strength is prepared, and a resin material is applied on the upper surface of the support substrate S by a spin coating method to form the interlayer insulating layer40. Then, as illustrated inFIG. 7B, the conductive layer31is formed on the upper surface of the interlayer insulating layer40. Preferably, as the formation method for the conductive layer31, a base metal film is formed using a thin-film formation process such as sputtering, and then copper (Cu) is grown by plating to a desired film thickness using an electroplating method. The conductive layers32to34to be formed subsequently are formed in the same manner.

The conductive layer31has a planar shape as illustrated inFIG. 9Aand includes the coil conductive pattern C1spirally wound in two turns and two electrode patterns51and61. The line A-A illustrated inFIG. 9Adenotes the cross section position ofFIG. 3, and the reference symbol B denotes the final product area of the coil component1.

Then, as illustrated inFIG. 9B, the interlayer insulating layer41that covers the conductive layer31is formed. Preferably, in the formation of the interlayer insulating layer41, a resin material is applied by a spin coating method, and then patterning is performed by photolithography. The interlayer insulating layers42to44to be formed subsequently are formed in the same manner. The interlayer insulating layer41has through holes101to103through which the conductive layer31is exposed. The through hole101is formed at a position through which the inner peripheral end of the coil conductive pattern C1is exposed, the through hole102is formed at a position through which the electrode pattern51is exposed, and the through hole103is formed at a position through which the electrode pattern61is exposed.

Then, as illustrated inFIG. 7C, the conductive layer is formed on the upper surface of the interlayer insulating layer41. The conductive layer32has a planar shape as illustrated inFIG. 9Cand includes the coil conductive pattern C2spirally wound in two turns and two electrode patterns52and62. As a result, the inner peripheral end of the coil conductive pattern C2is connected to the inner peripheral end of the coil conductive pattern C1through the through hole101. The electrode pattern52is connected to the electrode pattern51through the through hole102, and the electrode pattern62is connected to the electrode pattern61through the through hole103. A part of the electrode pattern52that is embedded in the through hole102constitutes the via conductor V1, and a part of the electrode pattern62that is embedded in the through hole103constitutes the via conductor V4.

Then, as illustrated inFIG. 9D, the interlayer insulating layer42that covers the conductive layer32is formed. The interlayer insulating layer42has through holes111to113through which the conductive layer32is exposed. The through hole111is formed at a position through which the outer peripheral end of the coil conductive pattern C2is exposed, the through hole112is formed at a position through which the electrode pattern52is exposed, and the through hole113is formed at a position through which the electrode pattern62is exposed. As is clear from comparison betweenFIG. 9BandFIG. 9D, the formation position of the through hole112is offset from the formation position of the through hole102, and the formation position of the through hole113is offset from the formation position of the through hole103.

Then, as illustrated inFIG. 7D, the conductive layer is formed on the upper surface of the interlayer insulating layer42. The conductive layer33has a planar shape as illustrated inFIG. 9Eand includes the coil conductive pattern C3spirally wound in two turns and two electrode patterns53and63. As a result, the outer peripheral end of the coil conductive pattern C3is connected to the outer peripheral end of the coil conductive pattern C2through the through hole111. The electrode pattern53is connected to the electrode pattern52through the through hole112, and the electrode pattern63is connected to the electrode pattern62through the through hole113. A part of the electrode pattern53that is embedded in the through hole112constitutes the via conductor V2, and a part of the electrode pattern63that is embedded in the through hole113constitutes the via conductor V5. The via conductor V2is formed at a position offset from the via conductor V1, and the via conductor V5is formed at a position offset from the via conductor V4.

Then, as illustrated inFIG. 9F, the interlayer insulating layer43that covers the conductive layer33is formed. The interlayer insulating layer43has through holes121to123through which the conductive layer33is exposed. The through hole121is formed at a position through which the inner peripheral end of the coil conductive pattern C3is exposed, the through hole122is formed at a position through which the electrode pattern53is exposed, and the through hole123is formed at a position through which the electrode pattern63is exposed. As is clear from comparison amongFIG. 9B,FIG. 9D, andFIG. 9F, the formation position of the through hole122is offset from the formation positions of the through holes102and112, and the formation position of the through hole123is offset from the formation positions of the through holes103and113.

Then, as illustrated inFIG. 7E, the conductive layer is formed on the upper surface of the interlayer insulating layer43. The conductive layer34has a planar shape as illustrated inFIG. 9Gand includes the coil conductive pattern C4spirally wound in two turns and two electrode patterns54and64. As a result, the inner peripheral end of the coil conductive pattern C4is connected to the inner peripheral end of the coil conductive pattern C3through the through hole121. The electrode pattern54is connected to the electrode pattern53through the through hole122, and the electrode pattern64is connected to the electrode pattern63through the through hole123. A part of the electrode pattern54that is embedded in the through hole122constitutes the via conductor V3, and a part of the electrode pattern64that is embedded in the through hole123constitutes the via conductor V6. The via conductor V3is formed at a position offset from the via conductors V1and V2, and the via conductor V6is formed at a position offset from the via conductors V4and V5.

Then, as illustrated inFIG. 7F, the interlayer insulating layer44that covers the conductive layer34is formed on the entire surface and is then patterned as illustrated inFIG. 9H. Specifically, the patterning is performed such that the coil conductive pattern C4and electrode patterns54and64are covered by the interlayer insulating layer44and that the remaining area is exposed.

Then, as illustrated inFIG. 8A, dry etching is performed using the patterned interlayer insulating layer44as a mask. As a result, a part of each of the interlayer insulating layers40to43that is not covered by the mask is removed, and a space is formed in the inner diameter area surrounded by the coil conductive patterns C1to C4and the coil external area positioned outside the coil conductive patterns C1to C4.

Then, as illustrated inFIG. 8B, a resin composite material containing the magnetic powder70is embedded in the space formed by the removal of the interlayer insulating layers40to43. As a result, the magnetic material layer12is formed above the coil conductive patterns C1to C4, and the magnetic member13is formed in the inner diameter area surrounded by the coil conductive patterns C1to C4and the coil external area positioned outside the coil conductive patterns C1to C4. After that, the support substrate S is peeled off, and the composite member is also formed on the lower surface side of the coil conductive patterns C1to C4to form the magnetic material layer11.

Then, as illustrated inFIG. 8C, dicing is performed for chip individualization. As a result, the electrode patterns51to54and61to64are partially exposed from the dicing surface. Further, as illustrated inFIG. 10which is an enlarged view of the area D3ofFIG. 8C, the cross section of the cut magnetic powder70, i.e., the body part71of the metal magnetic material is exposed from the dicing surface of the magnetic element body10. The dicing surface of the magnetic element body10refers to the surfaces S1, S3, S5, and S6. On the other hand, the surfaces S2and S4are not the dicing surface, and thus their surface conditions illustrated inFIG. 4are kept. That is, the cross section of the cut magnetic powder70is not exposed from the surfaces S2and S4of the magnetic element body10.

Then, the body part71of the magnetic powder70exposed from the dicing surface of the magnetic element body10is etched by acid. While there is no particular restriction on the type of acid to be used, an etchant having a higher etching rate for a material (iron or permalloy) constituting the body part71of the magnetic powder70than for copper (Cu) constituting the electrode patterns51to54and61to64is preferably used. This makes it possible to remove the body part71of the cut magnetic powder70while suppressing damage to the electrode patterns51to54and61to64exposed from the dicing surface of the magnetic element body10.

After removal of the body part71of the cut magnetic powder70, the surfaces S1, S3, S5, and S6each of which is the dicing surface have many recesses74as illustrated inFIG. 5. At this time, the etchant contacts also the surfaces S2and S4of the magnetic element body10; however, since the cross section of the cut magnetic powder70is not exposed from the surfaces S2and S4of the magnetic element body10, etching is not performed. Although there may be a case where the magnetic powder70is partially exposed from the surfaces S2and S4of the magnetic element body10, the surface of the magnetic powder70is covered with the insulating coat72, preventing the body part71from being etched. Thus, even when the above-described etching is performed, the surface roughness of each of the surfaces S2and S4of the magnetic element body10does not substantially change.

When barrel plating is performed in this state, the external terminals E1and E2are formed on the exposed surface of the electrode patterns51to54and the exposed surface of the electrode patterns61to64, respectively, as illustrated inFIG. 8D. At this time point, the magnetic powder70exposed from the dicing surface of the magnetic element body10has already been removed, so that no plating is formed on the magnetic powder70contained in the magnetic element body10.

Thus, the coil component1according to the present embodiment is completed.

As described above, in the present embodiment, after the coil component1is diced into individual semiconductor chips, the body part71of the magnetic powder70exposed from the dicing surface is removed by etching, so that it is possible to make the surface roughness of each of the surfaces S1, S3, S5, and S6each of which is the dicing surface larger than the surface roughness of each of the surfaces S2and S4each of which is a non-dicing surface. Thus, as described above, the creeping distance of each of the surfaces S1, S5, and S6of the magnetic element body10is increased, thus making it hard for the solder83to sneak to the surfaces S2and S4along the surfaces S1, S5, and S6.

In the above embodiment, surface treatment such as polishing or grinding is not applied to the surfaces S2and S4of the magnetic element body10. However, the surfaces S2and S4may be subjected to polishing or grinding for adjustment of the thickness of the coil component1. In this case, as illustrated inFIG. 11, the cross section of the cut magnetic powder70is exposed from the surfaces S2and S4of the magnetic element body10. Assume here that the surfaces S2and S4are subjected to polishing or grinding before chip individualization. In this case, when etching is applied to the entire surface of the magnetic element body10, the body part71of the magnetic powder70exposed from the surfaces S2and S4is inevitably etched, resulting in reduction in inductance. To prevent this, etching is applied with the surfaces S2and S4of the magnetic element body10masked. Alternatively, as illustrated inFIG. 12, an insulating coat75may be applied after polishing or grinding of the surfaces S2and S4to cover the surfaces S2and S4so as to prevent the body part71on the surfaces S2and S4from being etched. In this case, such an effect can also be obtained that dropping of the magnetic powder70during actual use is avoided.

For example, although the coil part20includes four conductive layers31to34in the above embodiment, the number of conductive layers is not limited to this in the present invention. Further, the number of turns of the coil conductive pattern formed in each conductive layer is not particularly limited.