Inductors

Abstract

The present invention provides an inductor with excellent connection reliability between the lead-out portion of the coil and the external electrode. The inductor comprises: a blank, including: a coil including a winding portion formed by winding a conductor having two opposing width surfaces and a pair of lead-out portions led out from the winding portion, and a magnetic portion including magnetic powder and burying the coil; and an external electrode, which is arranged on the surface of the blank and connected to the lead-out portion. The blank has a pair of first side surfaces opposed to each other. The lead-out portion has a first region on one width surface of the conductor, the first region is arranged substantially parallel to the first side surface, and is exposed from the first side surface and connected to the external electrode. The lead-out portion has a planar portion, which intersects the first region at an obtuse angle and extends to the end of the lead-out portion.

Description

Technical Field

[0001] The present invention relates to an inductor. Background Art

[0002] Patent document 1 describes a surface mount inductor comprising a coil and a molded body having a built-in coil and formed using a sealing material containing a resin and a magnetic material, wherein the surface of a conductor constituting a lead end of the coil is exposed on the surface of the molded body and connected to an external terminal formed of a conductive paste.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-120809 Summary of the invention

[0004] In order to reduce the DC resistance, in some inductors, a coil is formed of a thick conductor. In this case, due to the springback of the wound conductor, a part of the lead portion exposed from the blank is peeled off from the blank during the blank molding, and a poor connection with the external electrode occurs. An object of the present invention is to provide an inductor having excellent connection reliability between the lead portion of the coil and the external electrode.

[0005] The first mode is an inductor, comprising: a blank, including: a coil including a winding portion formed by winding a conductor having two opposing width surfaces and a pair of lead portions led out from the winding portion, and a magnetic portion including magnetic powder and in which the coil is embedded; and an external electrode, which is arranged on the surface of the blank and connected to the lead portion. The lead portion has a first region on one width surface of the conductor, the first region is arranged approximately parallel to the opposing first side surface of the blank, and is exposed from the first side surface and connected to the external electrode. Furthermore, the lead portion has a planar portion, which intersects the first region at an obtuse angle and extends to the end of the lead portion.

[0006] The second method is an inductor comprising: a blank including: a coil including a winding portion formed by winding a conductor having two opposing width surfaces and a pair of lead portions led out from the winding portion, and a magnetic portion including magnetic powder and in which the coil is embedded; and an external electrode arranged on the surface of the blank and connected to the lead portion. The blank has a pair of first side surfaces opposed to each other. The lead portion has a first region on one width surface of the conductor, the first region is arranged substantially parallel to the first side surface, and is exposed from the first side surface and connected to the external electrode. Furthermore, the lead portion has two bends, and the two bends are bent in opposite directions along the extension direction.

[0007] According to the present invention, it is possible to provide an inductor having excellent connection reliability between a lead portion of a coil and an external electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1This is a partial perspective view of the inductor of Example 1 as viewed from the second main surface side.

[0009] Figure 2 This is a partial perspective plan view of the element constituting the inductor of Example 1 as viewed from the second main surface side.

[0010] Figure 3 This is a schematic diagram for explaining an example of a method for manufacturing a coil constituting the inductor of the first embodiment.

[0011] Description of Reference Numerals

[0012] 10… green body; 30… coil; 40… external electrode; 100… inductor. DETAILED DESCRIPTION

[0013] The inductor of the first mode comprises: a blank, including: a coil including a winding portion formed by winding a conductor having two opposing width surfaces and a pair of lead portions led out from the winding portion, and a magnetic portion including magnetic powder and in which the coil is buried; and an external electrode, which is arranged on the surface of the blank and connected to the lead portion. The blank has a pair of first side surfaces opposed to each other. The lead portion has a first region on one width surface of the conductor, the first region is arranged substantially parallel to the first side surface, and is exposed from the first side surface and connected to the external electrode. Furthermore, the lead portion has a planar portion, the planar portion intersects the first region at an obtuse angle and extends to the end of the lead portion. In addition, the lead portion may have two bent portions, and the two bent portions are bent in opposite directions along the extension direction.

[0014] The inductor of the second mode comprises: a blank, including: a coil including a winding portion formed by winding a conductor having two opposing width surfaces and a pair of lead portions led out from the winding portion, and a magnetic portion including magnetic powder and in which the coil is buried; and an external electrode, which is arranged on the surface of the blank and connected to the lead portion. The blank has a pair of first side surfaces opposed to each other. The lead portion has a first region on one width surface of the conductor, the first region is arranged approximately parallel to the first side surface, and is exposed from the first side surface and connected to the external electrode. Furthermore, the lead portion has two bent portions, and the two bent portions are bent in opposite directions along the extension direction. In addition, the lead portion may have a planar portion, which intersects the first region at an obtuse angle and extends to the end of the lead portion.

[0015] The lead portion has a planar portion that intersects the first region at an obtuse angle and extends to the end of the lead portion, that is, the thickness of the conductor becomes thinner toward the end of the lead portion. When the blank is formed, the magnetic portion covers at least a portion of the planar portion of the end portion of the lead portion, the adhesion between the lead portion and the blank is improved, and the lead portion is inhibited from peeling off from the blank. As a result, the connection reliability between the lead portion and the external electrode is improved. In addition, the lead portion has a first region and a planar portion, so that the connection area with the external electrode becomes larger, and the DC resistance of the inductor can be reduced. In addition, the lead portion has two bent portions, and the area of ​​the lead portion exposed from the first side can be further increased. As a result, the connection reliability between the lead portion and the external electrode is improved, and the DC resistance of the inductor can be more effectively reduced.

[0016] The planar portion may also have a second region connected to the external electrode and a third region buried in the magnetic portion at the end side of the lead portion. By burying the end of the lead portion in the magnetic portion, the lead portion can be more effectively prevented from peeling off from the blank, thereby further improving the connection reliability between the lead portion and the external electrode.

[0017] The ratio of the length of the first region in the extension direction to the length of the first side in the width direction may also be greater than 1 / 3. By increasing the area of ​​the lead portion exposed from the first side, the connection area between the lead portion and the external electrode is further increased, the connection reliability is improved, and the DC resistance of the inductor can be more effectively reduced.

[0018] In this specification, the word "process" refers not only to an independent process, but also to a process that cannot be clearly distinguished from other processes as long as the desired purpose of the process is achieved. Below, the embodiments of the present invention are described based on the drawings. However, the embodiments shown below illustrate inductors that are used to concretize the technical ideas of the present invention, and the present invention is not limited to the inductors shown below. In addition, the components shown in the claims are by no means limited to the components of the embodiments. In particular, the size, material, shape, relative configuration of the constituent components described in the embodiments are not intended to limit the scope of the present invention to these unless there is a particularly specific description, but are simply illustrative examples. In addition, the same figure marks are marked for the same positions in the figures. Considering the ease of explanation or understanding of the key points, the embodiments are shown separately for convenience, but the structures shown in different embodiments can be partially replaced or combined.

[0019] Hereinafter, the present invention will be specifically described by way of Examples, but the present invention is not limited to these Examples.

[0020] Example 1

[0021] Reference Figures 1 to 3 The inductor of Example 1 is described. Figure 1This is a partial perspective view of the inductor 100 as viewed from the second main surface side. Figure 2 This is a partial perspective plan view of the element 10 constituting the inductor 100 as viewed from the second main surface side. Figure 3 This is a schematic diagram for explaining an example of a method for manufacturing the coil 30 constituting the inductor 100. Figure 1 In the diagram, there is a portion where dotted lines are used as auxiliary lines for representing the curved surface.

[0022] like Figure 1 as well as Figure 2 As shown in FIG. 1 , the inductor 100 includes a base body 10 including a coil 30 and a magnetic portion containing magnetic powder and resin and in which the coil 30 is embedded, and a pair of external electrodes 40 disposed on the surface of the base body 10 and electrically connected to the coil 30. The base body 10 has a substantially rectangular parallelepiped shape, and has a first main surface 12 on the mounting surface side, a second main surface 14 facing the first main surface 12 in the height direction (T direction), two first side surfaces 16 adjacent to and substantially orthogonal to the first main surface 12 and the second main surface 14 and facing each other in the length direction (L direction), and two second side surfaces 18 adjacent to and substantially orthogonal to the first main surface 12 and the first side surface 16 and facing each other in the width direction (W direction). The conductor forming the coil 30 has two width surfaces facing each other in the thickness direction of the conductor, and a cross section perpendicular to the extension direction has a substantially rectangular shape defined by the width and thickness of the conductor, and has a coating layer on the surface. The coil 30 has a winding portion 32 and a pair of lead portions, wherein the winding portion 32 is formed by winding a conductor having two opposing width surfaces around a winding axis N and making the width surfaces roughly parallel to the winding axis N into two upper and lower sections, and the pair of lead portions are led out from the outermost periphery of the winding portion 32.

[0023] The winding portion 32 of the coil 30 is formed by winding a conductor into a spiral shape so that the surface defined by the width of the conductor is substantially parallel to the winding axis and at least a portion of the surface defined by the width of the conductor overlaps, and is wound into two upper and lower sections connected at the innermost circumference and with the surfaces defined by the thickness of the conductor facing each other, so that both ends of the conductor are located at the outermost circumference, one width surface defined by the width of the conductor becomes the outer circumference side, and the other width surface becomes the inner circumference side (so-called α winding). That is, the conductor is wound into a spiral shape from the outer circumference to the inner circumference in the upper section of the winding portion 32, connected to the lower section at the innermost circumference, and wound into a spiral shape from the inner circumference to the outer circumference in the lower section. The coil 30 is buried in the blank 10 so that the winding axis N of the winding portion 32 is substantially orthogonal to the first main surface 12 and the second main surface 14 of the blank 10.

[0024] A pair of lead-out portions of the coil 30 includes a first lead-out portion led out from the outermost periphery of the upper section of the winding portion and a second lead-out portion led out from the outermost periphery of the lower section of the winding portion. For each lead-out portion of the coil 30, a first region 34 as a part thereof is arranged substantially parallel to each first side surface 16 of the blank 10, and the width surface of the conductor winding portion becoming the outer peripheral side is exposed from the first side surface 16 and buried in the blank 10. Each lead-out portion has a plane portion 36 that intersects the first region 34 at an obtuse angle toward its end and extends to the end of the lead-out portion. That is, the lead-out portion has a region where the thickness of the conductor decreases monotonically from the intersection line of the first region 34 and the plane portion 36 toward the end of the lead-out portion. A recess is provided on the first side surface 16 of the blank 10, in which the magnetic portion is missing corresponding to the reduction in the thickness of the conductor, and the second region 36A as a part of the plane portion is exposed. In other embodiments, the second region 36A may also be buried in the magnetic portion.

[0025] like Figure 2 As shown, the first region 34 arranges the width surface of the conductor approximately parallel to the first side surface 16 of the blank 10. The plane portion 36 provided continuously with the first region 34 intersects with the first region 34 at an obtuse angle θ. In addition, the plane portion 36 has a second region 36A and a third region 36B, wherein the second region 36A is continuous with the first region 34 and is exposed from the first side surface 16 to be connected to the external electrode, and the third region 36B is continuous with the second region 36A and is buried in the magnetic portion. That is, the end of the lead portion is buried in the magnetic portion. By burying the end of the lead portion, i.e., the third region 36B, in the magnetic portion, it is possible to more effectively suppress the lead portion from peeling off from the blank. In order to more effectively suppress peeling, the angle θ can be 100° or more.

[0026] The first region 34 exposed from the first side surface 16 has a length E1 in the W direction parallel to the first side surface 16, and is connected to an external electrode (not shown). The ratio of the length E1 of the first region 34 to the length of the first side surface 16 in the W direction may be greater than 1 / 3, or greater than 1 / 2. By having the length of the first region be greater than a specified value, the connection resistance with the external electrode can be further reduced. In addition, the lead portion has a first region 34 and a second region 36A as an exposed portion exposed from the first side surface 16 of the blank 10 and connected to the external electrode, and the exposed portion has a length E2 in the W direction parallel to the first side surface 16. The ratio of the length E2 to the length of the first side surface 16 in the W direction may be greater than 1 / 3, or greater than 1 / 2. By having the length of the exposed portion be greater than a specified value, the connection resistance with the external electrode can be further reduced.

[0027] The lead-out portion has two curved portions that are curved in opposite directions along the lead-out direction between the lead-out position of the winding portion 32 and the first region 34. Figure 2As shown, the conductor led out from the winding portion 32 has a first bent portion 38A and a second bent portion 38B, wherein the first bent portion 38A is bent along the extension direction toward the width surface side that becomes the outer peripheral side of the winding portion, and the second bent portion 38B is bent toward the width surface side that becomes the inner peripheral side of the winding portion. Thus, springback can be suppressed, and the length of the first region can be further extended, thereby further reducing the connection resistance between the coil and the external electrode.

[0028] In the inductor 100, as Figure 1 As shown, the external electrode 40 is arranged over the five surfaces of the first main surface 12, the first side surface 16, the second side surface 18 and the second main surface 14 of the blank 10, and is connected to the first area 34 of the lead portion of the coil 30 exposed in the first side surface 16. In addition, the conductive resin forming the external electrode is filled in the recessed portion provided on the first side surface 16, and the second area 36A of the planar portion is connected to the external electrode 40. The external electrode 40 can be a conductive resin layer containing conductive particles such as silver particles and copper particles and a binding resin. In addition, the external electrode 40 can include a plating layer formed on the conductive resin layer. The plating layer can include, for example, a layer formed of nickel and a layer formed of tin formed on the nickel layer. The area where the external electrode is formed can also be an area where the magnetic powder is exposed after removing a part of the resin constituting the blank and a part of the insulating layer covering the surface of the magnetic powder from the surface of the blank. In the area where the magnetic powder is exposed, part of the magnetic powder is connected to form a mesh structure, and the surface roughness increases. Therefore, in the case where the external electrode is a conductive resin layer, the adhesion to the blank is improved, and in the case where the external electrode is a plating layer, the plating layer is easy to grow.

[0029] Regarding the size of the blank 10, the length L is, for example, 1 mm to 3.4 mm, preferably 1 mm to 3 mm, the width W is, for example, 0.5 mm to 2.7 mm, preferably 0.5 mm to 2.5 mm, and the height T is, for example, 0.5 mm to 2 mm, preferably 0.5 mm to 1.5 mm. Specifically, the size of the blank, for example, L×W×T can be 1 mm×0.5 mm×0.5 mm, 1.6 mm×0.8 mm×0.8 mm, 2 mm×1.2 mm×1 mm, 2.5 mm×2 mm×1.2 mm.

[0030] The magnetic part constituting the blank 10 is formed of a composite material containing magnetic powder and resin. As the magnetic powder, iron-based metal magnetic powders such as Fe, Fe-Si, Fe-Ni, Fe-Si-Cr, Fe-Si-Al, Fe-Ni-Al, Fe-Ni-Mo, and Fe-Cr-Al, metal magnetic powders of other composition systems, metal magnetic powders such as amorphous materials, metal magnetic powders whose surfaces are covered with insulating layers such as glass, metal magnetic powders after surface modification, and nano-scale tiny metal magnetic powders are used. In addition, as the resin, thermosetting resins such as epoxy resins, polyimide resins, and phenolic resins, and thermoplastic resins such as polyethylene resins, polyamide resins, and liquid crystal polymers are used. The area ratio of the magnetic powder in the magnetic part is, for example, 50% or more and 85% or less, preferably 60% or more and 85% or less, or 70% or more and 85% or less. The area ratio can be obtained by dividing the total area of ​​the magnetic powder in a specified area that passes through the center of the inductor and exists in the central part of the cross section in the long side direction by the area of ​​the specified area.

[0031] The thickness of the conductor forming the coil can be, for example, greater than 0.01 mm and less than 1 mm. The width of the conductor can be, for example, greater than 0.1 mm and less than 2 mm. The aspect ratio (width / thickness) of the conductor cross section can be, for example, greater than 1 / 1, or greater than 1 / 1 and less than 30 / 1. In addition, the covering layer covering the conductor is formed of an insulating resin such as polyimide, polyamide-imide, etc., having a thickness of, for example, greater than 2 μm and less than 20 μm. A welding layer containing a self-welding component such as a thermoplastic resin or a thermosetting resin can also be further provided on the surface of the covering layer, and its thickness can also be formed to be greater than 1 μm and less than 8 μm. By providing a welding layer, the winding loosening of the winding portion can be more effectively suppressed.

[0032] A protective layer may also be arranged on the surface of the blank 10. The protective layer may be arranged on the surface of the blank other than the area where the external electrodes are arranged, or may be arranged on the surface of the blank other than the area where the first area of ​​the lead-out portion is exposed. The protective layer may, for example, be composed of a resin. As the resin constituting the protective layer, thermosetting resins such as epoxy resins, polyimide resins, and phenolic resins, and thermoplastic resins such as acrylic resins, polyethylene resins, and polyamide resins are used. The protective layer may also contain a filler. As the filler, non-conductive fillers such as silicon oxide and titanium oxide are used. For example, a resin composition containing a resin and a filler is applied to the surface of the blank by coating, impregnation, or the like, and the applied resin is cured as needed to form a protective layer. The protective layer may also be formed of an inorganic material such as water glass. In addition, the protective layer may also be formed in an area other than the area where the magnetic powder is exposed.

[0033] The blank may be provided with a mark (not shown). The mark may be provided, for example, on the second main surface of the blank where the lead portion is led out from the lower stage of the winding portion to indicate the polarity of the inductor. The mark may be provided, for example, by printing or laser marking.

[0034] Method for manufacturing an inductor

[0035] Next, a method for manufacturing an inductor is described. The inductor can be manufactured, for example, by the following manufacturing method, which includes: a coil forming step of winding a conductor to form a coil; a cutting step of cutting the terminal end of the lead portion of the formed coil to adjust it to a predetermined length; a blank forming step of burying the formed coil in a composite material including metal magnetic powder and resin with the terminal end (first region) of the lead portion exposed, and forming a blank consisting of the coil and the magnetic portion in which the coil is buried by applying pressure using a metal mold or the like; and an external electrode forming step of forming an external electrode connected to the terminal end of the lead portion exposed on the surface of the blank.

[0036] For example, using Figure 3 The coil holding portion of the cutting blade 220 and the receiving blade 210 shown in the figure are used to cut the terminal portion of the lead-out portion of the coil. Specifically, the winding portion of the coil 30 is stored in the coil holding portion, and the lead-out portion of the coil 30 is cut obliquely relative to the extending direction of the conductor by using the receiving blade 210 and the cutting blade 220, so that a flat portion is formed at the terminal of the lead-out portion.

[0037] In the above-mentioned inductor, although the case where the external electrodes are arranged over the five surfaces of a part of the first main surface, a part of the second main surface, a part of the second side surface and the first side surface of the blank is described, it can also be formed over a part of the first main surface and at least a part of the first side surface of the blank. It is also possible that only one lead portion has a planar portion that intersects the first area at an obtuse angle and extends to the end of the lead portion, and in addition, only one lead portion can have two curved portions that are bent in opposite directions along the extension direction. Although the cross section orthogonal to the extension direction of the conductor is set to a rectangular shape, it is not limited to a rectangular shape, and the corners can also be chamfered, and the sides can also be formed by curves such as semicircles and semi-ovals. The shape of the winding portion of the coil observed from the winding axis direction can also be a shape other than an oblong shape, such as a circular shape, an elliptical shape, a chamfered polygonal shape, etc. A recess (stand-off, interval) can be formed in the area of ​​the first main surface of the blank where the external electrode is not arranged. The shape of the height T direction of the recess set on the first main surface of the blank when viewed from the width W direction can also be a semicircular shape.

Claims

1. An inductor comprising: The blank comprises: A coil including a winding portion formed by winding a conductor having two opposing width surfaces and a pair of lead portions led out from the winding portion, and a magnetic portion including magnetic powder and burying the coil; and The external electrode is arranged on the surface of the green body and connected to the lead-out portion. The blank has a pair of first side surfaces facing each other. The lead portion has a first region on one width surface of the conductor, the first region is arranged substantially parallel to the first side surface, is exposed from the first side surface and is connected to the external electrode. The lead portion has a planar portion, the planar portion intersects the first region at an obtuse angle and extends to a terminal end of the lead portion, so that the thickness of the conductor decreases monotonically toward the terminal end of the lead portion. A portion of the planar portion is buried in the magnetic portion.

2. The inductor according to claim 1, wherein The lead portion has two bent portions, and the two bent portions are bent in opposite directions along the extending direction.

3. The inductor according to claim 1 or 2, wherein: The planar portion includes a second region and a third region, wherein the second region is connected to the external electrode, and the third region is buried in the magnetic portion at the distal end side of the lead portion.

4. The inductor according to claim 1 or 2, wherein: A ratio of a length of the first region in an extending direction to a length of the first side surface in a width direction is 1 / 3 or more.

Images