Patent ID: 12217902

DETAILED DESCRIPTION

Hereinafter, various embodiments and examples will be described with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and redundant description thereof will be omitted.

As shown inFIG.1, the coil component1according to one embodiment has a rectangular parallelepiped outer shape. As an example, the coil component1may be designed to have a long side of 1.2 mm, a short side of 1.0 min, and a height of 0.5 mm. Alternatively, as another example, the coil component1may be designed to have a long side of 2.0 mm, a short side of 1.2 mm, and a height of 0.6 mm.

The coil component1includes a pair of terminal electrodes5A and5B, an element body10, and a coil portion20embedded in the element body10.

The element body10has a rectangular parallelepiped outer shape and has six surfaces10ato10f. Among the surfaces10ato10fof the element body10, the upper surface10aand the lower surface10bare parallel to each other, the end surface10cand the end surface10dare parallel to each other, and the side surface10eand the side surface10fare parallel to each other. The pair of terminal electrodes5A and5B are provided on the end surfaces10cand10dof the element body10, respectively.

The element body10is made of a magnetic material. In the present embodiment, the element body10is made of a metal magnetic powder-containing resin, which is one kind of magnetic material. The metal magnetic powder-containing resin is a binding powder in which metal magnetic powder is bound by a binder resin. The metal magnetic powder may be configured of, for example, an iron-nickel alloy (a Permalloy alloy), carbonyl iron, an amorphous or crystalline FeSiCr-based alloy, Sendust, or the like. The binder resin is, for example, a thermosetting epoxy resin. In the present embodiment, a content of the metal magnetic powder in the binder powder is 80 to 92 vol % in percentage by volume and 95 to 99 wt % in percentage by mass. From the viewpoint of magnetic properties, the content of the metal magnetic powder in the binder powder may be 85 to 92 vol % in percentage by volume and 97 to 99 wt % in percentage by mass.

The coil portion20is configured to be provided with a first coil body30, a substrate40, and a second coil body50. Specifically, the first coil body30is provided on an upper surface40aof the substrate40positioned on the upper surface side of the element body10and the second coil body50is provided on a lower surface40bof the substrate40positioned on the lower surface side of the element body10, In the present embodiment, the pattern shape of the first coil body30viewed from the upper surface40aside of the substrate40is the same as the pattern shape of the second coil body50viewed from the lower surface40bside of the substrate40.

The substrate40is a plate-shaped member extending in parallel to the upper surface10aand the lower surface10bof the element body10. As shown inFIG.3, the substrate40has an elliptical ring-shaped coil forming portion41extending along the long side direction of the element body10, a pair of protruding portions46A and46B (exposed substrate portions) respectively extending from the coil forming portion41to the side surfaces10eand10fof the element body10and exposed from the side surfaces10eand10f, and a pair of frame portions47A and47B extending along the short side direction of the element body10and sandwiching the coil forming portion41from both sides. In addition, the coil forming portion41is provided with a circular through hole45in an edge portion of an oval opening42. The through hole45is filled with a via conductor, and an inner end portion32bof the first planar coil32and an inner end portion52bof the second planar coil52, which will be described later, are electrically connected to each other.

A substrate with a plate thickness of 60 μm which a glass cloth is impregnated with cyanate resin (Bismaleimide Triazine (BT) resin: registered trademark) can be used as the substrate40. Polyimide, aramid, and so on can be used besides the BT resin. Ceramic or glass can also be used as a material of the substrate40. A material of the substrate40may be a mass-produced printed board material. Particularly, a material of the substrate40may be a resin material used for a BT printed board, an FR4 printed board, or an FR5 printed board.

The first coil body30is provided on the upper surface40aof the substrate40in the coil forming portion41. As shown inFIG.4, the first coil body30is configured to be provided with a first planar coil32constituting a part of a coil22(inner conductor) of the coil component1and a first insulator34.

The first planar coil32is a substantially oval spiral air core coil wound around the opening42of the coil forming portion41in the same layer on the upper surface40aof the substrate40. The number of turns of the first planar coil32may be one or a plurality of turns. In the present embodiment, the number of turns of the first planar coil32is three to four. The first planar coil32has an outside end portion32a(first extracting end portion), an inside end portion32b(first connection end portion), and a first turn portion32cinterconnecting the outside end portion32aand the inside end portion32b. The outside end portion32ais provided so as to be exposed from the end surface10cof the element body10and connected to the terminal electrode5A. The inside end portion32his provided in the region that covers the through hole45of the substrate40when viewed from the thickness direction of the substrate40and has a circular shape. The first planar coil32is made of, for example, Cu and can be formed by electrolytic plating.

The first insulator34is provided on the upper surface40aof the substrate40and is a thick film resist patterned by known photolithography. The first insulator34defines the growth region of the first planar coil32and covers the first planar coil32in the same layer as the layer where the first planar coil32is formed. In the present embodiment, the first insulator34includes an outer wall34aand an inner wall34bdefining the contour of the first planar coil32, a partition wall34cseparating the inside and outside turns of the first turn portion32cof the first planar coil32. The first insulator34is made of, for example, an epoxy resin.

The first insulator34further includes a pair of protruding portions36A and36B. The protruding portions36A and36B extend so as to overlap the protruding portions46A and46B of the substrate40, and are exposed from the side surfaces10eand10fof the element body10, respectively. In the present embodiment, each of the protruding portions36A and36B has a rectangular cross-sectional shape orthogonal to the extending direction and a rectangular end surface shape.

The first planar coil32is plated and grown in a growth region defined by the first insulator34. The first planar coil32includes a seed pattern32dpatterned on the upper surface40aof the substrate40and a plated portion32egrown on the seed pattern32d.

As shown inFIG.5, the first coil body30further includes a protective film38integrally covering the first planar coil32and the first insulator34from the upper surface10aside of the element body10. The protective film38is made of, for example, an epoxy resin. The protective film38enhances the insulation between the first planar coil32and the metal magnetic powder contained in the element body10.

The second coil body50is provided on the lower surface40bof the substrate40in the coil forming portion41. As shown inFIG.5, the second coil body50is configured to be provided with a second planar coil52constituting a part of the coil22of the coil component1, a second insulator54.

The second planar coil52is a substantially oval spiral air core coil wound around the opening42of the coil forming portion41in the same layer on the lower surface40bof the substrate40. The number of turns of the second planar coil52may be one or a plurality of turns. In the present embodiment, the number of turns of the second planar coil52is three to four. The second planar coil52has an outside end portion52a(second extracting end portion), an inside end portion52b(second connection end portion), and a second turn portion52cinterconnecting the outside end portion52aand the inside end portion52b. The outer end portion52ais provided so as to be exposed from the end surface10dof the element body10and connected to the terminal electrode5B. The inside end portion52bis provided in the region that covers the through hole45of the substrate40when viewed from the thickness direction of the substrate40and has a circular shape. The second planar coil52is made of, for example, Cu and can be formed by electrolytic plating.

The second insulator54is provided on the lower surface40bof the substrate40and is a thick film resist patterned by known photolithography. The second insulator54defines the growth region of the second planar coil52and covers the second planar coil52in the same layer as the layer where the second planar coil52is formed. In the present embodiment, the second insulator54includes an outer wall54aand an inner wall54bdefining the contour of the second planar coil52, a partition wall54cseparating the inside and outside turns of the second turn portion52cof the second planar coil52. The second insulator54is made of, for example, an epoxy resin.

The second insulator54further includes a pair of protruding portions56A and56D. The protruding portions56A and56B extend so as to overlap the protruding portions46A and46B of the substrate40, and are exposed from the side surfaces10eand10fof the element body10, respectively. In the present embodiment, each of the protruding portions56A and56D has a rectangular cross-sectional shape orthogonal to the extending direction and a rectangular end surface shape.

The second planar coil52is plated and grown in a growth region defined by the first insulator54in the same manner as the first planar coil32. The second planar coil52includes a seed pattern52dpatterned on the lower surface40bof the substrate40and a plated portion52egrown on the seed pattern52d.

As shown inFIG.5, the second coil body50further includes a protective film58integrally covering the second planar coil52and the second insulator54from the lower surface10bside of the element body10. The protective film58is made of, for example, an epoxy resin. The protective film58enhances the insulation between the second planar coil52and the metal magnetic powder contained in the element body10.

The respective inside end portions32band52bof the first planar coil32provided on the upper surface40aof the substrate40and the second planar coil52provided on the lower surface40bof the substrate40are interconnected via the via conductor in the through hole45penetrating the substrate40in the thickness direction. In the present embodiment, the first planar coil32, the second planar coil52, and the via conductor constitute the air core coil22around the opening42of the substrate40. The coil22has a coil axis parallel to the thickness direction of the substrate40(that is, the direction in which the upper surface10aand the lower surface10bface each other).

The first planar coil32and the second planar coil52are wound such that electric currents flow in the same direction (that is, the same circumferential direction when the substrate40is viewed from the thickness direction) when a voltage is applied between both end portions of the coil22(that is, the outside end portion32aof the first planar coil32and the outside end portion52aof the second planar coil52). In the present embodiment, the first planar coil32has a clockwise circumferential direction from the outside end portion32ato the inside end portion32bas shown inFIG.3and the second planar coil52has a clockwise circumferential direction from the inside end portion52bto the outside end portion52aas shown inFIG.5. Electric currents flow in the same direction through the first planar coil32and the second planar coil52, and thus generated magnetic fluxes are superposed and reinforce each other.

As described above, in the coil component1, the protruding portions46A and46B of the substrate40, the protruding portions36A and36B of the first insulator34, and the protruding portions56A and56B of the second insulator54are exposed on the side surfaces10eand10fof the element body10, respectively. More specifically, the protruding portion46A (exposed substrate portion) of the substrate40, the protruding portion36A (first exposed insulator portion) of the first insulator34, and the protruding portion56A (second exposed insulator portion) of the second insulator54are exposed on the side surface10e(first side surface) of the element body10, and the protruding portion46B (exposed substrate portion) of the substrate40, the protruding portion36B (first exposed insulator portion) of the first insulator34, and the protruding portion56B (second exposed insulator portion) of the second insulator54are exposed on the side surface10f(second side surface) of the element body10.FIG.7shows the exposed configuration on the side surface10eof the element body10. The exposed configuration on the side surface10fof the element body10is also the same as that on the side surface10e, and thus the description thereof will be omitted.

As shown inFIG.7, the protruding portion36A of the first insulator34and the protruding portion56A of the second insulator54overlap each other via the protruding portion46A of the substrate40. In the present embodiment, the protruding portion36A of the first insulator34and the protruding portion56A of the second insulator54have the same end surface dimension, and entirely overlap with each other via the protruding portion46A of the substrate40.

FIG.8shows an exposed configuration on the side surface of the element body according to the conventional art, in which the protruding portion36A of the first insulator34and the protruding portion56A of the second insulator54are separated from each other and do not overlap at all. The inventors have found that it is difficult to further improve the DC superposition characteristics when the protruding portion36A of the first insulator34and the protruding portion56A of the second insulator54are separated from each other as shown inFIG.8. In addition, it has been found that it is difficult to achieve high pressure resistance to the pressure in the thickness direction applied to the protruding portion46A of the substrate40in the region between the protruding portion36A of the first insulator34and the protruding portion56A of the second insulator54.

In the coil component1, as shown inFIG.7, the protruding portion36A of the first insulator34and the protruding portion56A of the second insulator54are overlapped with each other via the protruding portion46A of the substrate40, thereby improving the DC superposition characteristics. The protruding portion36A of the first insulator34and the protruding portion56A of the second insulator54do not necessarily completely overlap each other, and may partially overlap each other.

In the coil component1, also in the side surface10fopposed to the side surface10e, the protruding portion36B of the first insulator34and the protruding portion56B of the second insulator54overlap with each other via the protruding portion46B of the substrate40at a position corresponding to the position on the side surface10e.

In the coil component1, the first planar coil32and the second planar coil52have elliptical shapes, and the first planar coil32and the second planar coil52have the shortest distance from the side surfaces10eand10fat the center position of the side surfaces10eand10fof the element body10. Since this portion has a small magnetic volume in the element body10and is likely to cause magnetic flux saturation, the DC superposition characteristics can be more effectively improved by arranging the protruding portion36A of the first insulator34, the protruding portion56A of the second insulator54, and the protruding portion46A of the substrate40at this position.

As shown inFIG.9, the seed pattern32dof the first planar coil32and the seed pattern52dof the second planar coil52may be extended to the side surfaces10eand10fof the element body10and exposed from the side surfaces10eand10fof the element body10. Any one of the seed pattern32dof the first planar coil32and the seed pattern52dof the second planar coil52may be exposed from the side surfaces10eand10fof the element body10.