Inductors

Abstract

The present invention provides an inductor that can simplify the manufacturing process. The inductor comprises: a coil having a winding portion and a lead portion; a substrate containing the coil inside, the substrate including a magnetic portion, and having a bottom surface and end surfaces adjacent to the bottom surface and opposite to each other; and an external electrode arranged on at least the bottom surface of the substrate and connected to the lead portion. The coil is arranged so that the winding axis direction intersects the bottom surface. The cross section of the conductor is a roughly rectangular shape defined by thickness and width, and the conductor has: a pair of first surfaces defined by an extension direction and a thickness direction, and a pair of second surfaces defined by an extension direction and a width direction. The winding portion is wound into a spiral shape with one side of the second surface as the outer peripheral side and the other side of the second surface as the inner peripheral side, and is wound into two layers connected at the innermost peripheral part, and the two ends of the conductor are located at the outermost peripheral part of each layer of the winding portion. The lead portion has the second surface led out toward the bottom surface direction roughly parallel to the winding axis direction, and one side of the first surface of its front end is connected to the external electrode at the bottom surface.

Description

Technical Field

[0001] The present invention relates to inductors. Background Art

[0002] The electronic component described in Patent Document 1 is formed by folding the two ends of a coil at the end of a T-core and leading them out to the bottom side, and connecting them to external electrodes arranged on the bottom surface. The above-mentioned coil is formed by winding a conductive wire with a rectangular cross-section around a T-core containing resin and magnetic powder.

[0003] Patent Document 1: U.S. Patent Application Publication No. 2016 / 0012962

[0004] In the manufacture of the electronic component described in Patent Document 1, in order to fold back the two ends of the coil to the bottom side and lead them out, it is necessary to twist the wire with a rectangular cross section by about 90 degrees in the middle and then fold it back at the end of the T-core. Therefore, it is necessary to twist the manufacturing process of the wire, which has a technical problem in improving productivity. In addition, since the T-core has a certain degree of thickness, it is difficult to achieve a further low-profile. Summary of the invention

[0005] An object of one embodiment of the present invention is to provide an inductor capable of simplifying the manufacturing process.

[0006] The inductor of this mode comprises: a coil having a winding portion formed by winding a conductor and a pair of lead portions led out from the winding portion; a substrate containing the coil inside, the substrate including a magnetic portion, the substrate having a bottom surface and end surfaces adjacent to the bottom surface and facing each other, wherein the magnetic portion contains magnetic powder and resin; and a pair of external electrodes arranged on at least the bottom surface of the substrate and electrically connected to the pair of lead portions respectively. The coil is arranged so that the winding axis direction of the winding portion intersects with the bottom surface of the substrate. The cross section of the conductor perpendicular to the extension direction is a roughly rectangular shape defined by thickness and width, and the conductor has a pair of first faces defined by the extension direction and the thickness direction, and a pair of second faces defined by the extension direction and the width direction. The conductor of the winding portion is wound in a spiral shape with one second face as the outer peripheral side and the other second face as the inner peripheral side, and the conductor is wound into two layers connected at the innermost peripheral part, and the two ends of the conductor are located at the outermost peripheral part of each layer of the winding portion. The lead portion is led out toward the bottom surface with the second surface being substantially parallel to the winding axis direction, and one first surface of a front end portion of the lead portion is connected to the external electrode on the bottom surface of the base.

[0007] According to one embodiment of the present invention, it is possible to provide an inductor whose manufacturing process can be simplified. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a partially transparent perspective view of the inductor of Example 1 as viewed from the upper surface side.

[0009] Figure 2 This is a partially transparent plan view of the inductor of Example 1 as viewed from the upper surface side.

[0010] Figure 3 This is a partially transparent plan view of the inductor of Example 1 as viewed from the end surface side.

[0011] Figure 4 This is a partially transparent perspective view of the inductor of Example 2 as viewed from the upper surface side.

[0012] Figure 5 This is a partially transparent perspective view of the inductor of Example 3 as viewed from the upper surface side.

[0013] Description of Reference Numerals

[0014] 100, 200, 300…inductor; 10…substrate; 30…coil; 40…external electrode. DETAILED DESCRIPTION

[0015] The inductor comprises: a coil having a winding portion formed by winding a conductor and a pair of lead portions led out from the winding portion; a substrate containing the coil inside, the substrate including: a magnetic portion having a bottom surface and end surfaces adjacent to the bottom surface and facing each other, wherein the magnetic portion comprises magnetic powder and resin; and a pair of external electrodes arranged on at least the bottom surface of the substrate and electrically connected to the pair of lead portions respectively. The coil is arranged so that the winding axis direction of the winding portion intersects with the bottom surface of the substrate. The cross section of the conductor perpendicular to the extension direction is a substantially rectangular shape defined by thickness and width, and the conductor has a pair of first surfaces defined by the extension direction and the thickness direction, and a pair of second surfaces defined by the extension direction and the width direction. The conductor of the winding portion of the coil is wound in a spiral shape with one second surface as the outer peripheral side and the other second surface as the inner peripheral side, and the conductor is wound into two layers connected at the innermost peripheral part, and a first surface of one layer is opposed to a first surface of the other layer, and both ends of the conductor are located at the outermost peripheral part of each layer of the winding portion. The conductor lead portion has a second surface of the conductor led out toward the bottom surface substantially parallel to the winding axis direction of the winding portion, and a first surface of the conductor at a front end of the lead portion is connected to an external electrode on the bottom surface of the base.

[0016] The lead-out portion of the coil is led out toward the bottom surface in a manner that the second surface of the conductor is substantially parallel to the winding axis direction of the coil, and one side of the first surface is arranged on a plane substantially the same as the bottom surface, so that a portion of the front end portion of the conductor and the external electrode can be connected without twisting the conductor. In addition, since there is no need to fold back the conductor, it is easy to further reduce the height of the inductor.

[0017] In the above-mentioned inductor, a second surface of the front end portion of the lead portion may be connected to an external electrode at an end surface of the substrate, and the external electrode is arranged from the bottom surface to the end surface of the substrate. One side of the first surface of the conductor is arranged on a plane substantially identical to the bottom surface of the substrate, and one side of the second surface as an outer peripheral side of the conductor is arranged on a plane substantially identical to the end surface of the substrate, and connected to the external electrode arranged from the bottom surface to the end surface of the substrate, thereby widening the connection area between the conductor and the external electrode, reducing the DC resistance of the inductor, and improving the fixing strength to the substrate during mounting.

[0018] The coil may also have a region where the thickness of the conductor at the front end of the lead portion is greater than the thickness of the conductor at the winding portion, and the width of the conductor at the front end of the lead portion is smaller than the width of the conductor at the winding portion. There is a region where the first surface of the conductor is widened at the front end of the lead portion, and the region is arranged on a surface substantially the same as the bottom surface of the substrate, so that the connection area between the conductor and the external electrode is widened, and the DC resistance of the inductor is reduced.

[0019] In this specification, the term "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 can be achieved. The following describes the embodiments of the present invention based on the drawings. However, the embodiments shown below are examples of inductors for embodying 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 dimensions, materials, shapes, and relative arrangements of the components described in the embodiments are not intended to limit the scope of the present invention to these unless otherwise specified, and are merely examples. In addition, in each figure, the same reference numerals are marked for the same parts. Considering the ease of explanation or understanding of the key points, the embodiments are shown separately for convenience, but partial replacement or combination of the structures shown in different embodiments can be performed. After Example 2, the description of matters common to Example 1 is omitted, and only the differences are described. In particular, the same effects of the same structure are not mentioned sequentially in each embodiment.

[0020] Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

[0021] (Example 1)

[0022] Reference Figure 1 to Figure 3 The inductor of Example 1 is described. Figure 1 This is a partially transparent perspective view of the inductor 100 as viewed from the upper surface side. Figure 2 This is a partially transparent plan view of the inductor 100 as viewed from the upper surface side. Figure 3This is a partial transparent plan view of the inductor 100 as viewed from the end surface side.

[0023] like Figure 1 As shown, the inductor 100 includes: a coil 30 having a winding portion 32 formed by winding a conductor around a winding axis N and a pair of lead portions 34 led out from the winding portion 32; a base 10 containing the coil 30 inside, the base 10 including a magnetic portion containing magnetic powder and resin; and a pair of external electrodes 40 arranged over the bottom surface 12 and the end surface 14 of the base 10, and electrically connected to the front end portions 36 of the lead portions of the coil on the bottom surface 12. The base 10 includes: a bottom surface 12 on the mounting surface side; an upper surface 16 facing the bottom surface 12 in the height direction (T direction); two end surfaces 14 adjacent to and substantially orthogonal to the bottom surface 12, and the two end surfaces 14 facing each other in the length direction (L direction); and two side surfaces 18 adjacent to and substantially orthogonal to the bottom surface 12 and the end surface 14, and the two side surfaces 18 facing each other in the width direction (W direction).

[0024] The conductor forming the coil 30 has a covering layer on the surface, and the cross-sectional shape of the conductor orthogonal to the extension direction (length direction) is a roughly rectangular shape defined by the thickness t and the width w, or a roughly square shape. In addition, the conductor has a pair of first faces 22 and a pair of second faces 24, wherein the pair of first faces 22 are defined by the extension direction of the conductor and the thickness t direction, and are opposite to each other, and the pair of second faces 24 are defined by the extension direction of the conductor and the width direction w, and are opposite to each other. The thickness t of the conductor can be, for example, greater than 0.2 mm and less than 1 mm. The width w of the conductor can be, for example, greater than 0.2 mm and less than 1 mm. The aspect ratio (t / w) of the conductor cross section can be, for example, greater than 1 / 1.3, and preferably can also be approximately 1 / 1. In addition, the covering layer of the conductor is formed by an insulating resin such as polyimide, polyamide-imide, etc., with a thickness of, for example, greater than 2 μm and less than 10 μm. In order to prevent the winding portion from unwinding, a welding layer containing a self-adhesive component such as a thermoplastic resin or a thermosetting resin may be further provided on the surface of the cover layer, and the thickness of the welding layer may be formed to be 1 μm or more and 3 μm or less.

[0025] The winding portion 32 of the coil 30 is wound in a spiral shape in such a manner that both ends of the conductor are located at the outermost circumference, one second surface 24 of the conductor is on the outer circumference side, and the other second surface 24 is on the inner circumference side, and the winding portion 32 is wound into two sections, the two sections are connected at the innermost circumference, and one first surface 22 of one section and one first surface of the other section are opposite to each other (so-called α winding). The coil 30 is contained inside the base 10 in such a manner that the winding axis N of the winding portion 32 intersects with the bottom surface 12 and the upper surface 16 of the base 10.

[0026] like Figure 2 as well as Figure 3As shown in FIG. 1 , the lead portion 34a has its front end 36a led out from the outermost circumference of the upper section on the upper surface 16 side of the winding portion 32 toward one side surface 18 of the base. The lead portion 34b has its front end 36b led out from the outermost circumference of the lower section on the bottom surface 12 side of the winding portion 32 toward one side surface 18 of the base. The front end portions 36a and 36b are led out in the same side direction in such a manner that the second surface 24 of the conductor as the outer circumference side is away from the end surface 14 of the base. The lead portions 34a and 34b are led out in the bottom surface direction of the base in such a manner that the second surface 24 of the conductor is approximately parallel to the winding axis of the winding portion 32. In the front end portions 36a and 36b, one side of the first surface 22 of the conductor is respectively arranged on the same plane as the bottom surface 12, and is exposed from the bottom surface 12 of the base to be connected to the external electrode 40. That is, the conductor is led out in the bottom surface direction without being twisted about the extending direction. In the front end portions 36 a and 36 b , one first surface 22 of the conductor exposed from the bottom surface 12 of the base is electrically connected to the external electrode 40 .

[0027] The aspect ratio (t / w) of the conductor cross section may be larger than 1 / 1. In this case, the winding portion becomes a so-called α-winding coil that is wound along the edge. If such a wire is used, the conductor can be more easily led to the bottom surface without twisting.

[0028] The substrate 10 may have a substantially rectangular parallelepiped shape. The size of the substrate 10 is as follows: the length L is, for example, 1 mm or more and 3.4 mm or less, preferably 1 mm or more and 3 mm or less, the width W is, for example, 0.5 mm or more and 2.7 mm or less, preferably 0.5 mm or more and 2.5 mm or less, and the height T is, for example, 0.5 mm or more and 2 mm or less, preferably 0.5 mm or more and 1.5 mm or less. Specifically, as the size of the substrate, L×W×T may be, for example, 1 mm×0.5 mm×0.5 mm, 1.6 mm×0.8 mm×0.8 mm, 2 mm×1.2 mm×1 mm, or 2.5 mm×2 mm×1.2 mm.

[0029] The magnetic part constituting the substrate 10 is formed by a composite material containing a magnetic powder and a binder such as a resin. As the magnetic powder, metal magnetic powders of iron systems such as Fe, Fe-Si, Fe-Ni, Fe-Si-Cr, Fe-Si-Al, Fe-Ni-Al, Fe-Ni-Mo, 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 insulators such as glass, metal magnetic powders after surface modification, and nano-scale tiny metal magnetic powders can be used. In addition, as an example of a binder, a resin such as an epoxy resin, a polyimide resin, a thermosetting resin such as a benzene resin, a thermoplastic resin such as a polyethylene resin, a polyamide resin, and a liquid crystal polymer can be used. The filling rate of the magnetic powder in the composite material is, for example, 50% by mass or more and 85% by mass or less, preferably 60% by mass or more and 85% by mass or less, or 70% by mass or more and 85% by mass.

[0030] A protective layer (not shown) may also be arranged on the surface of the substrate 10. The protective layer may be arranged on the surface of the substrate other than the area where the external electrodes are arranged. The protective layer is, for example, configured to contain a resin. As the resin constituting the protective layer, thermosetting resins such as epoxy resins, polyimide resins, and benzene resins, and thermoplastic resins such as acrylic resins, polyethylene resins, and polyamide resins may be used. The protective layer may also contain a filler. As the filler, non-conductive fillers such as silicon oxide and titanium oxide may be used. The protective layer is formed, for example, by applying a resin composition containing a resin and a filler to the surface of the substrate by coating, impregnation, or the like, and curing the applied resin as needed.

[0031] The base 10 may be provided with a mark (not shown). The mark may be provided, for example, on the side of the upper surface 16 of the base where the lead portion 34b is led out from the lower stage of the winding portion 32 to indicate the polarity of the inductor. The mark may be provided, for example, by printing or laser marking.

[0032] In the inductor 100, the external electrode 40 is arranged over the bottom surface 12 and the end surface 14 of the substrate. The external electrode 40 is arranged to be electrically connected to the first surface 22 of the conductor at the front end portion 36 of the lead portion. The external electrode 40 can be formed, for example, by plating. The external electrode 40 formed by plating can include: a first layer formed of copper, a second layer formed on the first layer and formed of nickel, and a third layer formed on the second layer and formed of tin. In addition, the external electrode 40 can also be formed by applying a conductive paste to form a conductive layer. The conductive paste can contain conductive particles such as silver particles and copper particles and a binder resin. Furthermore, the external electrode 40 can also include a plating layer formed on the conductive layer.

[0033] The inductor 100 can be manufactured, for example, by a manufacturing method including the following steps: a coil forming step of forming a conductor into a desired shape to form a coil; a substrate forming step of burying the formed coil in a composite material including magnetic powder and resin so that one side of the first surface of the front end portion of the lead portion is exposed, and pressurizing the substrate using a metal mold or the like to mold the substrate; and an external electrode forming step of forming an external electrode on the bottom surface exposed on the first surface.

[0034] (Example 2)

[0035] Reference Figure 4 The inductor according to Example 2 is described. Figure 4 The inductor 200 is a partially transparent perspective view of the inductor 200 as viewed from the upper surface. The inductor 200 of the second embodiment is configured similarly to the inductor 100 of the first embodiment, except that the front end portion 36 of the lead portion places the second surface 24 of the outer peripheral side of the conductor on a substantially coplanar surface with the end surface 14 of the substrate and is exposed from the end surface 14 of the substrate.

[0036] In the inductor 200, at the leading end portion 36 of the lead portion, one side of the first side 22 of the conductor forming the coil is arranged on a substantially flush plane with the bottom side 12 of the substrate and is exposed from the bottom side 12 of the substrate. In addition, one side of the second side 24 of the conductor is arranged on a substantially flush plane with the end side 14 of the substrate and is exposed from the end side 14 of the substrate. The external electrode 40 is arranged on the surface of the conductor exposed from the substrate and is electrically connected.

[0037] In the inductor 200, the two surfaces of the conductor are electrically connected to the external electrode 40, so that the connection area between the conductor and the external electrode is widened, and the DC resistance of the inductor is reduced. In addition, the external electrode 40 is formed over the bottom surface 12 and the end surface 14 of the base body, and is L-shaped when viewed from the side direction (W direction). This can improve the fixing strength to the substrate during mounting.

[0038] (Example 3)

[0039] Reference Figure 5 The inductor according to the third embodiment will be described. Figure 5 This is a partially transparent perspective view of the inductor 300 as viewed from the upper surface side. The inductor 300 of the third embodiment is configured similarly to the inductor 100 of the first embodiment, except that the front end portion 36 of the lead portion has a region where the thickness of the conductor is greater than the thickness of the conductor of the winding portion and the width of the conductor is smaller than the width of the conductor of the winding portion, and the external electrode 40 is disposed only on the bottom surface 12 of the base.

[0040] In the inductor 300, the conductor is compressed in the width direction and expanded in the thickness direction at the front end portion 36 of the lead portion. Thus, the thickness of the conductor at the front end portion 36 is greater than the thickness of the conductor at the winding portion. On the other hand, the width of the conductor at the front end portion is smaller than the width of the conductor at the winding portion. Figure 5 In the embodiment, the region compressed in the width direction is formed from the end of the conductor toward the lead portion 34. One side of the first surface 22a extending in the thickness direction is arranged on a plane substantially the same as the bottom surface 12 of the substrate and is exposed from the bottom surface 12 of the substrate. The first surface 22a exposed from the bottom surface 12 of the substrate is electrically connected to the external electrode 40 arranged on the bottom surface 12 of the substrate. On the other hand, the second surface 24a, which is compressed and has a smaller width, is arranged away from the end surface 14 of the substrate.

[0041] In the inductor 300 , the connection area between the external electrode 40 and the front end portion 36 of the conductor can be widened, and the DC resistance of the inductor can be reduced.

[0042] In the above-mentioned inductor, the case where the external electrodes are arranged over the bottom surface and end surface of the substrate is described, but they can also be formed on at least one of the upper surface and side surface of the substrate. The end surface of the conductor in the extension direction can also be arranged on a plane roughly the same as the side surface of the substrate and exposed from the side surface of the substrate. The cross-section perpendicular to the extension direction of the conductor is rectangular, but is not limited to a rectangle. The corners can also be chamfered, and the edges can also be composed of 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, for example, a circle, an ellipse, a chamfered polygon, etc. The protective layer can also be formed of an inorganic material such as water glass instead of a resin composition containing a filler and a resin. A recess (gap) can be formed in an area of ​​the bottom surface of the substrate where the external electrode is not arranged. The shape of the recess set in the bottom surface of the substrate in the height T direction observed from the width W direction can also be a semicircular shape.

Claims

1. An inductor comprising: The coil has a winding portion formed by winding a conductor and a pair of lead portions led out from the winding portion; A substrate contains the coil inside, the substrate includes a magnetic portion, and has a bottom surface and end surfaces adjacent to and opposite to the bottom surface, wherein: The magnetic part comprises magnetic powder and resin; and a pair of external electrodes, disposed on at least the bottom surface of the substrate, and electrically connected to the pair of lead portions, respectively; The coil is arranged so that the winding axis direction of the winding portion intersects with the bottom surface of the base body. The cross section of the conductor perpendicular to the extension direction is a substantially rectangular shape defined by thickness and width, and the conductor has a pair of first surfaces defined by the extension direction and the thickness direction, and a pair of second surfaces defined by the extension direction and the width direction. The conductor of the winding portion is wound in a spiral shape with one side of the second surface as the outer peripheral side and the other side of the second surface as the inner peripheral side, and the conductor is wound into two layers connected at the innermost peripheral part, and both ends of the conductor are located at the outermost peripheral part of each layer of the winding portion, The lead-out portion leads the second surface toward the bottom surface substantially parallel to the direction of the reel. One of the first surfaces of the front end portion of the lead portion is connected to an external electrode on the bottom surface of the base.

2. The inductor according to claim 1, wherein One of the second surfaces of the front end of the lead portion is connected to an external electrode at an end surface of the base body. The external electrode is arranged from the bottom surface to the end surface.

3. The inductor according to claim 1 or 2, wherein: The coil has a region where the thickness of the conductor at the front end of the lead portion is greater than the thickness of the conductor at the winding portion, and where the width of the conductor at the front end of the lead portion is smaller than the width of the conductor at the winding portion.

Images