JP7735964B2 - inductor - Google Patents

Description

The present invention relates to an inductor .

Patent Document 1 discloses a coil component having an element body (magnetic body portion) containing magnetic particles and resin, a coil conductor embedded in the element body, and a pair of external electrodes electrically connected to the ends of the coil conductor, in which the coated portion between the lead-out portions (exposed portions) located at both ends of the coil conductor is positioned inside the surface of the element body where the external electrodes are located. Patent Document 1 also describes treating the periphery of the lead-out portion exposed from the element body with laser light, and then forming the external electrodes by plating.

JP 2018-85459 A

By irradiating the area of the element body surface where the external electrodes will be formed with the laser light, the insulating film on the magnetic particles is removed from the element body surface, facilitating the growth of a plating layer during subsequent external electrode formation. However, because the laser light also evaporates and removes the coating layer on the coil conductor, removing the coating in the thickness direction of the lead-out portion at the boundary between the element body and the lead-out portion on the element body surface can create a deep gap toward the interior of the element body. This deep gap can remain as a void beneath the plating layer during subsequent external electrode formation, and can cause poor connection if the plating between the lead-out portion and external electrode is not formed thick enough.

In an inductor in which an external electrode is formed by irradiating a region of the element body surface, including the lead portion of the coil conductor exposed from the element body, with laser light, the present invention aims to prevent the occurrence of deep gaps that can form at the boundary between the lead portion on the element body surface and the element body, leading into the interior of the element body, thereby suppressing poor connections between the lead portion and the external electrode.

One aspect of the present invention is an inductor comprising an element body including a coil conductor wound around a strip-shaped conductor having a coating layer, and a core containing magnetic particles and resin in which the coil conductor is embedded, wherein two opposing flat main surfaces and two adjacent opposing side surfaces of the strip-shaped conductor protrude toward the outside of the strip-shaped conductor in a cross-sectional view in the thickness direction of the strip-shaped conductor, and have ridge lines on the side surfaces, and at an extraction portion extracted from the winding portion of the coil conductor, one of the flat main surfaces and a portion of the protruding side surface of the strip-shaped conductor that is closer to the surface of the element body than the ridge line are exposed from the surface of the element body, and are in contact with the element body on the inside side of the element body than the ridge line, and the coating layer extends toward the inside side of the element body than the ridge line, and an external electrode is formed on the portion of the extraction portion exposed from the surface of the element body.

In an inductor in which an external electrode is formed by irradiating a region of the element body surface, including the lead portion of the coil conductor exposed from the element body, with laser light, this invention can prevent the occurrence of deep gaps that can form at the boundary between the lead portion on the element body surface and the element body, leading into the interior of the element body, thereby suppressing the occurrence of poor connections between the lead portion and the external electrode.

1 is a perspective view of an inductor according to an embodiment of the present invention, viewed from above; FIG. 2 is a perspective view of the inductor as viewed from the bottom side. FIG. 2 is a perspective view showing the internal configuration of an inductor. 1A to 1C are schematic diagrams illustrating a manufacturing process of an inductor. FIG. 2 is a cross-sectional view of a coil conductor taken along a plane in the thickness direction. FIG. 2 is a cross-sectional view of an element body showing an example of a configuration in the vicinity of a lead portion. FIG. 7 is a partial detailed view of part A in the cross-sectional view shown in FIG. 6 . FIG. 10 is a cross-sectional view of an element body showing another example of the configuration in the vicinity of the lead-out portion. FIG. 9 is a partial detailed view of part B in the cross-sectional view shown in FIG. 8 . 10 is a micrograph of a cross section of an element body showing an example of a configuration in the vicinity of an extraction portion. FIG. 1 is a cross-sectional view of an element body including a cross-section in the thickness direction of a lead portion in the prior art.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of the inductor according to this embodiment as viewed from the top surface 12 side, and FIG. 2 is a perspective view of the inductor as viewed from the bottom surface 10 side.
The inductor of this embodiment is configured as a surface-mount electronic component, and includes a body 2 having an approximately rectangular parallelepiped shape, which is one form of an approximately hexahedral shape, and a pair of external electrodes 4 provided on the surface of the body 2.

Hereinafter, in the base body 2, the first main surface that faces the mounting substrate (not shown) during mounting is defined as the bottom surface 10, the second main surface opposite the bottom surface 10 is called the top surface 12, a pair of third main surfaces that are perpendicular to the bottom surface 10 are called end surfaces 14, and a pair of fourth main surfaces that are perpendicular to the bottom surface 10 and the pair of end surfaces 14 are called side surfaces 16.
1, the distance from the bottom surface 10 to the top surface 12 is defined as the thickness T of the element body 2, the distance between a pair of side surfaces 16 is defined as the width W of the element body 2, and the distance between a pair of end surfaces 14 is defined as the length L of the element body 2. Furthermore, the direction of the thickness T is defined as the thickness direction DT, the direction of the width W is defined as the width direction DW, and the direction of the length distance is defined as the length direction DL.
The size of the inductor is, for example, a length L of 2.0 mm, a width W of 1.6 mm, and a thickness T of 1.1 mm.

FIG. 3 is a perspective view showing the internal configuration of the inductor.
The element body 2 includes a coil conductor 20 and a substantially hexahedral core 30 in which the coil conductor 20 is embedded, and is configured as a molded inductor in which the coil conductor 20 is sealed in the core 30 .

The core 30 is a molded body formed by compressing and heating a powder mixture of magnetic particles and resin, with the coil conductor 20 enclosed inside, into an approximately hexahedral shape.

The magnetic particles of this embodiment include particles of two particle sizes: first magnetic particles that are large particles with a relatively large average particle size, and second magnetic particles that are small particles with a relatively small average particle size. As a result, during compression molding, the second magnetic particles, which are small particles, enter between the first magnetic particles, along with the resin, thereby increasing the filling rate of the magnetic particles in the core 30 and also increasing the magnetic permeability.
In this embodiment, the average particle sizes of the metal particles of the first and second magnetic particles are 24.4 μm and 1.7 μm, respectively. The average particle size of the first magnetic particles is preferably 7 μm or more and 60 μm or less, and the average particle size of the second magnetic particles is preferably 1 μm or more and 4 μm or less. Furthermore, the magnetic particles may contain particles with an average particle size different from that of the first and second magnetic particles, thereby containing particles of three or more different particle sizes.

The first magnetic particles and the second magnetic particles are both particles having a metal particle and an insulating film covering the surface of the metal particle, the insulating film having a thickness of several nanometers to several tens of nanometers. By covering the metal particle with the insulating film, the insulation resistance and the withstand voltage are increased.
In the first magnetic particles of this embodiment, the metal particles are made of Fe—Si—B amorphous alloy powder, and the insulating film is made of zinc phosphate glass with a thickness of 10 nm to 50 nm.In addition, in the second magnetic particles of this embodiment, the metal particles are made of carbonyl iron powder, and the insulating film is made of a silica film with a thickness of 5 nm to 15 nm.

In the mixed powder of this embodiment, the resin material is an epoxy resin containing a phenol alkyl type epoxy resin as a main component.
In this embodiment, the composition of the mixed powder is 75±10 wt % of first magnetic particles, 25±10 wt % of second magnetic particles, and 2.7 wt % to 3.5 wt % of resin.

As shown in FIG. 3 , the coil conductor 20 includes a winding portion 22 around which a conducting wire is wound, and a pair of lead-out portions 24 that are led out from the winding portion 22 .
The coil conductor 20 is composed of a conductor wire and a coating layer formed on the surface of the conductor wire. The conductor wire is a copper strip-shaped conductor wire (so-called flat conductor wire) with a rectangular cross section, with a thickness of 18 μm to 90 μm and a width of 240 μm to 340 μm. The coating layer is composed of an insulating layer formed on the surface of the strip-shaped conductor wire and a fusion layer formed on the surface of the insulating layer to bond the overlapping strip-shaped conductor wires together in the winding portion 22. The insulating layer is made of polyimide amide resin and has a thickness of 6±2 μm. The fusion layer is made of polyimide resin and has a thickness of 2.5±1.0 μm. The thickness surface of the coil conductor may be curved, and the width of the conductor wire includes the curved portion of the thickness.

The winding portion 22 of the coil conductor 20 is formed by winding a ribbon-shaped conductor wire (hereinafter simply referred to as the conductor wire) in a spiral shape, with both ends drawn out to the outer periphery and connected to each other at the inner periphery. Inside the element body 2, the coil conductor 20 is embedded in the core 30 with the central axis of the winding portion 22 oriented along the thickness direction DT of the element body 2. The drawing portions 24 are drawn out from the winding portion 22 to each of a pair of end faces 14, with one main surface exposed from the element body 2 and the other main surface embedded in the element body 2. The one main surface of the drawing portion 24 exposed from the element body 2 is electrically connected to the external electrode 4.

The pair of external electrodes 4 are so-called L-shaped electrodes, consisting of L-shaped members extending from each of the end faces 14 of the element body 2 to the bottom face 10. Each external electrode 4 is connected to the lead-out portion 24 of the coil conductor 20 at the end face 14, and the portion 4A (Figure 2) extending to the bottom face 10 is electrically connected to wiring on the circuit board by an appropriate mounting means such as solder.

An element protection layer (not shown) is formed on the surface of the element body 2 excluding the area of the external electrodes 4. The element protection layer is made of, for example, phenoxy resin and novolac resin, and contains nanosilica as a filler. The element protection layer is formed on the surface of the element body 2 to a thickness of 10 μm or more and 30 μm or less.

Inductors with this configuration can improve DC bias characteristics by using soft magnetic materials for the magnetic particles, and are therefore used as electronic components in electrical circuits through which large currents flow, as choke coils in DC-DC converter circuits and power supply circuits, and as electronic components in electronic devices such as personal computers, DVD players, digital cameras, TVs, mobile phones, smartphones, car electronics, and medical and industrial machinery. However, the uses of inductors are not limited to these, and they can also be used in tuning circuits, filter circuits, rectifying and smoothing circuits, etc.

FIG. 4 is a schematic diagram of the manufacturing process of the inductor.
As shown in the figure, the manufacturing process of an inductor includes a coil conductor forming step, a preform forming step, a thermoforming and hardening step, a barrel polishing step, and an external electrode forming step.

The coil conductor formation process is a process for forming the coil conductor 20 from a conducting wire. In this process, the coil conductor 20 is formed into a shape having the aforementioned winding portion 22 and a pair of lead-out portions 24 by winding the conducting wire using a winding method known as "alpha winding." Alpha winding refers to a state in which the conducting wire, which functions as a conductor, is wound in two spiral stages so that the lead-out portions 24 at the beginning and end of the winding are located on the outer periphery. There is no particular limitation on the number of turns in the coil conductor 20.

The preform forming step is a step of forming a preform called a tablet.
The preform is formed by pressing the above-mentioned mixed powder, which is the material of the base body 2, into a solid form that is easy to handle. In this embodiment, two types of tablets are formed: a first tablet of an appropriate shape (e.g., E-shaped) with a groove into which the coil conductor 20 fits, and a second tablet of an appropriate shape (e.g., I-shaped or plate-shaped) that covers the groove of the first tablet.

In the thermoforming and curing process, the first tablet, coil conductor, and second tablet are placed in a molding die, and while applying heat, pressure is applied in the overlapping direction of the first tablet and second tablet, curing them to integrate the first tablet, coil conductor, and second tablet. This results in the formation of the element body 2, in which the coil conductor 20 is enclosed in the core 30. The thermoforming and curing process corresponds to the element body molding process in this disclosure.

The barrel polishing process involves barrel polishing this molded body, which rounds the corners of the element body 2.

The external electrode formation process is a process for forming the external electrode 4 on the core 30, and includes an element protection layer formation process, a surface treatment process, and a plating layer formation process.

The element protection layer formation process involves coating the entire surface of this molded body with an insulating resin.

The surface treatment process involves modifying the surface of the planned electrode locations on the surface of the core 30 by irradiating the locations with laser light. Here, the planned electrode locations refer to the areas on the surface of the core 30 where the external electrodes 4 are to be formed, including the areas where the lead-out portions 24 are exposed. Specifically, by irradiating the laser light, the element protective layer on the surface of the core 30 and the coating layer on the lead-out portions 24 of the coil conductor 20 are removed within the planned electrode locations, the resin on the surface of the core 30 is removed, and the insulating film on the surfaces of the magnetic particles exposed from the core 30 is also removed. As a result, the exposed area of the metal of the magnetic particles per unit area on the surface of the core 30 is larger in the planned electrode locations than in other surface areas of the core 30. After irradiating the laser light, a cleaning process (e.g., etching) may be performed to clean the surfaces of the planned electrode locations.

In the plating layer formation process, copper is barrel-plated onto the surface of the core 30, forming a copper plating layer at the electrode locations irradiated with laser light. In addition, the plating layer may be formed by providing a Ni plating layer and a Sn plating layer on top of the copper plating layer.

By the external electrode forming step, the external electrodes 4 made of the plating layers are formed.
The external electrode 4 is not limited to an L-shaped electrode, but may be a so-called five-sided electrode that is provided over the entire end face 14 and over a portion of each of the bottom face 10, the top face 12, and a pair of side faces 16 adjacent to the end face 14. When the five-sided electrode is applied by immersion in a conductive resin, the element protective layer forming step is not necessarily required.

As mentioned above in the background art, in the surface treatment process, laser light is applied to the planned electrode locations on the surface of the element body, removing the element body protective layer and the coil conductor coating layer from the core surface and also removing the insulating film from the magnetic particles on the surface of the element body, facilitating the growth of a plating layer in the subsequent formation of external electrodes. However, because the boiling point of the coating layer of the coil conductor that makes up the lead portion is generally lower than the melting point of the magnetic particles, this laser light irradiation can create deep gaps at the boundary between the lead portion and the element body on the surface of the element body due to the evaporation and removal of the coating layer toward the interior of the element body.

Figure 11 is a cross-sectional view of element body 72, including a thickness-wise cross-section of lead portion 74, of a conventional inductor. As shown in Figure 11, coating layer 74b formed on the surface of lead wire 74a of lead portion 74 is evaporated and removed on the left and right side surfaces of lead portion 74 by irradiation with laser light from above, potentially creating a deep gap 76 extending through the entire thickness of lead portion 74 between lead portion 74 and element body 72. Furthermore, such deep gap 76 is likely to create a void in the gap 76 when forming the plating layer that constitutes external electrode 75 in the subsequent external electrode formation process, potentially causing poor connection between lead wire 74a of lead portion 74 and external electrode 75.

For this reason, in this embodiment, the strip-shaped conductor constituting the coil conductor 20 is particularly configured so that the two opposing main surfaces and the two adjacent opposing side surfaces of the strip-shaped conductor form curved surfaces that protrude outward in a curved manner when viewed in cross section in the thickness direction of the strip-shaped conductor. The metal layer (plating layer in this embodiment) of the external electrode 4 is formed on at least a portion of the portion of the lead-out portion 24 exposed from the surface of the element body 2, closer to the surface of the element body 2 than the ridge line of the protruding side surface of the strip-shaped conductor, and the coating layer of the strip-shaped conductor is configured to extend from the ridge line toward the interior of the element body 2.

Figure 5 is a cross-sectional view of the coil conductor 20 in this embodiment, taken along a plane in the thickness direction of the coil conductor 20 (i.e., a plane perpendicular to the length direction). The coil conductor 20 has a strip-shaped conductive wire 20a and a coating layer 20b formed on the surface of the strip-shaped conductive wire 20a. The coating layer 20b includes an insulating layer 25a formed on the surface of the strip-shaped conductive wire 20a and a fusion layer 25b formed on the surface of the insulating layer 25a. Note that in Figure 5, the points indicated by white and black circles form lines extending normal to the page.

The ribbon conductor 20a is particularly configured so that the two opposing main surfaces 26 and the two adjacent opposing side surfaces 27 protrude in a curved manner toward the outside of the ribbon conductor 20a in a cross-sectional view of the thickness direction of the ribbon conductor 20a shown in Figure 5, forming a curved surface with a ridge line 27a (position indicated by a black circle in the figure). Here, the distance from the reference plane RP, which passes through the boundary 26a (position indicated by a white circle in the figure) between the flat main surface 26 and the side surface 27 and is perpendicular to the main surface 26, is defined as the height h of the ridge line 27a.

Figure 6 shows an example of the configuration of the vicinity of the lead-out portion 24 in the inductor 1, and is a diagram showing a cross section of the element body 2 including the lead-out portion 24, taken along a plane that passes through the center of the width W of the inductor 1 and is perpendicular to the width direction DW. Figure 7 is a partial detailed view of part A in Figure 6.

Generally, when laser light is irradiated onto the electrode locations of the element body 2 during the surface treatment process, the volume of the element body 2 at the electrode locations is reduced due to factors such as the removal of resin contained in the element body 2, causing the surface of the element body 2 to sink inward.

In the example shown in Figures 6 and 7, the intensity and/or irradiation time of the laser light irradiated from above in the surface treatment process is adjusted, causing the surface of the element body 2 to sink to the depth of the ridge line 27a of the ribbon-shaped conductor 20a that constitutes the draw-out portion 24. This laser light irradiation evaporates and removes the coating layer 20b of the draw-out portion 24, but the portion of the surface of the draw-out portion 24 below the ridge line 27a, i.e., the portion closer to the interior of the element body 2 than the ridge line 27a, is shaded by the laser light irradiated from above in the illustration, and therefore the coating layer 20b in this shaded portion is not removed (hereinafter, this phenomenon is also referred to as the "shade effect caused by the ridge line 27a"). As a result, the gap 28 that forms at the boundary between the draw-out portion 24 and the element body 2 is wedge-shaped, tapering toward the interior of the element body 2.

In other words, due to the above-mentioned shading effect, the coating layer 20b on the surface of the lead-out portion 24 that is closer to the interior of the element body 2 than the ridge line 27a is not removed, and therefore this gap 28, unlike the gap 76 in the prior art shown in Figure 11, does not become a deep gap that extends to the depth of the lower surface of the lead-out portion 24 (the surface on the interior side of the element body 2) (i.e., does not extend the entire thickness of the lead-out portion 24). In other words, in the inductor 1, the formation of a deep gap that extends the entire thickness of the lead-out portion 24 toward the interior of the element body 2 at the boundary between the lead-out portion 24 and the element body 2 on the surface of the element body 2 is prevented.

Then, the plating layer 5 of the external electrode 4 is formed on the surface of the strip-shaped conductor 20a in the portion of the lead-out portion 24 where the coating layer 20b has been removed. As shown in Figures 6 and 7, the plating layer 5 of the external electrode 4 extends over the entire curved surface of the lead-out portion 24, except for the surface that is closer to the interior of the element body 2 than the ridge 27a of the curved surface that constitutes the side surface 27 of the strip-shaped conductor 20a. This allows the DC resistance value of the inductor 1 to be reduced.

Note that the plating layer 5 of the external electrode 4 does not necessarily have to be formed on the entire surface of the strip-shaped conductor 20a above the ridge 27a as shown in Figures 6 and 7. The plating layer 5, which is the metal layer of the external electrode 4, need only extend to at least a portion of the curved surface of the strip-shaped conductor 20a at the lead-out portion 24, excluding the portion of the curved surface that is located inside the element body 2 from the ridge of the curved surface that constitutes the side surface 27. Even with this configuration, it is possible to prevent the formation of deep gaps between the element body 2 and the lead-out portion 24, effectively suppressing the occurrence of poor connections between the lead-out portion 24 and the external electrode 4, while reducing the DC resistance value of the inductor 1.

Figure 8 shows another example (variant) of the configuration of the vicinity of the lead-out portion 24 in the inductor 1. Like Figure 7, Figure 8 shows a cross section of the lead-out portion 24 and the surrounding element body 2 along a plane that passes through the center of the width W of the inductor 1 and is perpendicular to the width direction DW. Figure 9 is a partial detailed view of part B in Figure 8.

In the example shown in Figures 8 and 9, the surface of the element body 2 is shallower than in the example shown in Figures 6 and 7, and is limited to a depth between the illustrated upper surface of the drawn-out portion 24 and the ridge line 27a. This configuration can be achieved by adjusting the amount of laser light irradiated from above in the surface treatment process to be less than in the example shown in Figures 6 and 7 (for example, by adjusting the intensity of the laser light to be less and/or the irradiation time to be shorter).

As in the examples of Figures 6 and 7, the coating layer 20b on the lead-out portion 24 is evaporated and removed by the irradiation of this laser light. However, because the amount of laser light irradiation is adjusted to be small, the coating layer 20b on the side surface 27 of the ribbon-shaped conductor 20a of the lead-out portion 24 is not removed to the depth of the ridge 27a, but is removed partway down, forming a small V-shaped depression 29, as shown in Figures 8 and 9.

Then, the plating layer 5 of the external electrode 4 is formed on the surface of the strip-shaped conductor 20a in the portion of the lead-out portion 24 where the coating layer 20b has been removed. As a result, as shown in Figures 8 and 9, the plating layer 5 of the external electrode 4 is formed so as to extend over part of the curved surface that constitutes the side surface 27 of the strip-shaped conductor 20a, excluding the portion of the surface that is located inside the element body 2 from the ridge line 27a.

When the laser light irradiation dose is adjusted to a low level as described above, the coating layer 20b is not removed to the depth of the ridge line 27a. Therefore, in an ideal state where the adjusted irradiation dose is maintained constant, the shading effect caused by the ridge line 27a, as shown in Figures 6 and 7, does not occur. However, in an actual laser device that may be used in the manufacturing process, the intensity of the output laser light may fluctuate depending on the performance of the laser device and the operating environment conditions.

Even in such cases, with the configuration of the inductor 1 according to this embodiment, even if the amount of laser light irradiated onto the element body 2 exceeds the design value due to fluctuations in the intensity of the laser light during the surface treatment process, and the coating layer 20b is removed to the depth of the ridge 27a, the above-mentioned shading effect prevents the formation of deep gaps between the element body 2 and the lead portion 24, effectively suppressing poor connections between the lead portion 24 and the external electrode 4.

Figure 10 is a micrograph of a cross section of the element body 2 of the inductor 1, corresponding to the cross section shown in Figure 6. In the micrograph shown in Figure 10, the boundary line between the strip conductor 20a and the plating layer 5 of the external electrode 4 is thin, so the outline of the strip conductor 20a is shown in Figure 10 as a dotted frame. In the example of Figure 10, the amount of laser light irradiation is slightly weaker than in the example shown in Figure 6, and the coating layer 20b near the ridge 27a of the strip conductor 20a still remains.

To effectively utilize the shading effect of the ridges 27a described above, it is preferable that the height h (Figure 5) of the ridges 27a of the ribbon-shaped conductor 20a be 8 μm or greater. If the height h of the ridges 27a is less than 8 μm, when laser light is irradiated to remove the coating layer 20b to the depth of the ridges 27a, the heat transmitted through the element body 2 may be transferred around and remove the coating layer 20b located further inside the element body 2 than the ridges 27a, increasing the likelihood of a deeper gap occurring between the lead-out portion 24 and the element body.

All of the above-described embodiments and modifications are merely examples of one aspect of the present invention, and any modifications and applications are possible within the scope of the present invention.
Furthermore, unless otherwise specified, the horizontal, vertical, and other directions, various numerical values, shapes, and materials in the above-described embodiments include a range (so-called equivalent range) that produces the same effect as those directions, numerical values, shapes, and materials.

[Configuration supported by the above embodiment]
The above-described embodiment supports the following configurations.

(Configuration 1) An inductor comprising an element body including a coil conductor wound with a strip-shaped conductor having a coating layer, and a core containing magnetic particles and resin in which the coil conductor is embedded, wherein an external electrode is formed on the exposed portion of the lead-out portion drawn out from the winding portion of the coil conductor from the surface of the element body, and two side surfaces of the strip-shaped conductor adjacent to and facing the two opposing main surfaces protrude toward the outside of the strip-shaped conductor in a cross-sectional view in the thickness direction of the strip-shaped conductor, and in the exposed portion of the lead-out portion from the surface of the element body, the external electrode is formed on at least a part of the surface side of the element body from the ridge line of the protruding side surfaces of the strip-shaped conductor, and the coating layer extends from the ridge line toward the interior of the element body.
In the inductor of configuration 1, when the element body is irradiated with laser light for surface treatment in the manufacturing process, the surface of the lead portion that is located from the ridge toward the interior of the element body is not hit by the laser light and is not surface treated. As a result, the inductor of configuration 1 can prevent the occurrence of deep gaps that extend across the entire thickness of the lead portion at the boundary between the lead portion and the element body on the surface of the element body, thereby suppressing the occurrence of poor connections between the lead portion and the external electrodes.

(Configuration 2) The inductor according to configuration 1, wherein the external electrodes are made of metal layers.
According to the inductor of configuration 2, even in a configuration in which a coating layer is formed on the surface of the strip-shaped conductor constituting the lead-out portion, and the coating layer on the side of the strip-shaped conductor is removed by irradiation with laser light during the manufacturing process, leaving a gap within the element, it is possible to prevent the occurrence of deep gaps that extend through the entire thickness of the lead-out portion, thereby suppressing the occurrence of poor connections between the lead-out portion and the external electrode.

(Configuration 3) An inductor described in configuration 1 or 2, wherein the height of the ridge formed by the side surface of the strip-shaped conductor is 8 μm or more, measured using a plane that passes through the boundary point between the main surface and the side surface and is perpendicular to the main surface as a reference plane.
In the inductor of configuration 3, heat generated in the element body by irradiation with laser light for surface treatment during the manufacturing process can be prevented from traveling within the element body and causing surface treatment to extend to the portion of the surface of the lead portion that is closer to the interior of the element body than the ridge line. This effectively prevents the occurrence of deep gaps that extend toward the interior of the element body at the boundary between the lead portion and the element body on the surface of the element body, and more effectively suppresses poor connections between the lead portion and the external electrode.

(Configuration 4) A method for manufacturing an inductor, comprising: an element molding process in which a coil conductor having a strip-shaped conductor wound around it is embedded in a core containing magnetic particles and resin so that the surface of the lead-out portion led out from the winding portion of the coil conductor is exposed from the surface of the core, and the core is pressed to form an element; a surface treatment process in which laser light is irradiated to planned electrode locations on the surface of the element body, including the portions where the lead-out portion is exposed, to perform surface treatment on the surfaces of the element body and the lead-out portion; and a plating process in which a plating layer is formed on the surfaces of the lead-out portion exposed from the element body to form external electrodes, wherein the strip-shaped conductor has a coating layer formed on its surface, and two side surfaces adjacent to the two opposing main surfaces of the strip-shaped conductor protrude toward the outside of the strip-shaped conductor in a cross-sectional view in the thickness direction of the strip-shaped conductor, and in the surface treatment process, the coating layer is removed from portions of the surface of the lead-out portion that include at least a part of the side surfaces other than the surfaces that are inside the element body relative to the ridge lines of the protruding side surfaces of the strip-shaped conductor.
According to the inductor manufacturing method of configuration 4, it is possible to prevent the occurrence of deep gaps that extend into the inside of the element body at the boundary between the lead portion on the surface of the element body and the element body, and to stably manufacture inductors that are free from poor connections between the lead portion and the external electrode.

1...inductor, 2, 72...element body, 4...external electrode, 5...plating layer, 10...bottom surface, 12...top surface, 14...end surface, 16...side surface, 20...coil conductor, 20a...strip-shaped conductor, 20b, 74b...coating layer, 22...winding portion, 24, 74...lead-out portion, 25a...insulating layer, 25b...fusion layer, 26...main surface, 26a...boundary, 27...side surface, 27a...ridge line, 28, 76...gap, 29...recess, 30...core, 74a...conductor.

Claims (3)

The magnetic coil comprises an element body including a coil conductor wound with a strip-shaped conductive wire having a coating layer, and a core including magnetic particles and a resin in which the coil conductor is embedded,
two side surfaces of the strip-shaped conductor adjacent to the two flat main surfaces facing each other protrude outward from the strip-shaped conductor in a cross-sectional view in a thickness direction of the strip-shaped conductor, and have ridges on the side surfaces;
In the lead-out portion led out from the winding portion of the coil conductor, the strip-shaped conductor wire is
one of the flat principal surfaces and a portion of the protruding side surface of the strip-shaped conductor that is closer to the surface of the element body than the ridge line are exposed from the surface of the element body;
the coating layer is in contact with the element body on an inner side of the element body from the ridge line, and the coating layer extends from the ridge line to an inner side of the element body,
an external electrode is formed on a portion of the lead portion that is exposed from the surface of the element body;
Inductor. The external electrodes are made of metal layers.
10. The inductor of claim 1. the height of the ridge line formed by the side surface of the strip-shaped conductor is 8 μm or more, measured using a plane that passes through a boundary point between the main surface and the side surface and is perpendicular to the main surface as a reference plane;
3. The inductor according to claim 1 or 2.