Inductor

Abstract

To provide an inductor for large current which has larger allowable current and low inductance.SOLUTION: An inductor includes an element assembly containing metal magnetic particles and a resin, and a conductor embedded in the element assembly. The element assembly has a mounting surface directed to the side of a mounting substrate at the time of mounting, a pair of end faces perpendicular to the mounting surface, and a pair of side faces perpendicular to the mounting surface and the pair of end faces. The conductor has: two conductor parts which have plate shapes, and extend between the pair of end faces inside the element assembly; a pair of main electrode parts which are provided on one ends of the respective two conductor parts, and are exposed from the same one end faces to the mounting surface; a connection part for connecting the other ends of the two conductor parts; and an auxiliary electrode part which is provided on the other ends of the two conductor parts, and is exposed from the mounting surface.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a coil device that has a flat conductor and two flat cores that sandwich the conductor, as an inductor that can achieve a large allowable current and low inductance. The two cores are made of ferrite and are joined to each other by adhesive, sandwiching the conductor between them. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-141110 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in general, ferrite exhibits a large decrease in inductance value relative to temperature, and the inductance value decreases sharply due to magnetic saturation, so that the allowable current of an inductor using ferrite can be limited to a small value.

[0005] An object of the present invention is to provide a large current inductor having a larger allowable current and a lower inductance. [Means for solving the problem]

[0006] One aspect of the present invention is an inductor comprising a base body containing metal magnetic particles and a resin, and a conductor embedded in the base body, wherein the base body has a mounting surface that faces a mounting board when mounted, a pair of end faces perpendicular to the mounting surface, and a pair of side surfaces perpendicular to the mounting surface and the pair of end faces, and the conductor is plate-shaped and has two conductor portions that extend inside the base body between the pair of end faces, a pair of main electrode portions provided at one end of each of the two conductor portions and exposed from the same one end face to the mounting surface, a connection portion that connects the other ends of the two conductor portions to each other, and auxiliary electrode portions provided at the other ends of the two conductor portions and exposed from the mounting surface. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a large current inductor having a larger allowable current and a low inductance. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of an inductor according to a first embodiment of the present invention, viewed from the top side. [Figure 2] FIG. 2 is a perspective view of one end face of the inductor as viewed from the mounting surface side. [Figure 3] FIG. 10 is a perspective view of the other end face of the inductor as viewed from the mounting surface side. [Figure 4] FIG. 2 is a perspective view showing the internal configuration of an inductor. [Figure 5] 2A and 2B are diagrams illustrating the configuration of a conductor according to the first embodiment. [Figure 6] FIG. 10 is a perspective view of one end face of the inductor according to the second embodiment. [Figure 7] FIG. 10 is a perspective view of the other end face of the inductor according to the second embodiment. [Figure 8] 10A and 10B are diagrams illustrating the configuration of a conductor according to a second embodiment. [Figure 9] FIG. 11 is a perspective view of one end face of the inductor according to the third embodiment. [Figure 10]FIG. 11 is a perspective view of the other end face of the inductor according to the third embodiment. [Figure 11] 10A and 10B are diagrams illustrating the configuration of a conductor according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The inductor of the present invention will be described below with reference to the drawings. [1. First embodiment] FIG. 1 is a perspective view of an inductor 1 according to a first embodiment of the present invention viewed from the top surface 12 side, and FIGS. 2 and 3 are perspective views of different end faces 14 viewed from the mounting surface 10 side. The inductor 1 of this embodiment is configured as a surface-mount electronic component, and includes an element body 2 having a substantially rectangular parallelepiped shape, which is one form of a substantially hexahedral shape; a pair of main electrodes 4; and an auxiliary electrode 5.

[0010] Hereinafter, in the element body 2, the first main surface that faces the mounting board (not shown) during mounting is defined as the mounting surface 10, the second main surface opposite the mounting surface 10 is referred to as the top surface 12, a pair of third main surfaces that are perpendicular to the mounting surface 10 are referred to as end surfaces 14, and a pair of fourth main surfaces that are perpendicular to the mounting surface 10 and the pair of end surfaces 14 are referred to as side surfaces 16.

[0011] In this embodiment, the inductor 1 has a pair of main electrodes 4 provided from one end face 14 to the mounting surface 10, and an auxiliary electrode 5 provided from the other end face 14 to the mounting surface 10. Hereinafter, of the pair of end faces 14, one face on which the main electrode 4 is provided may be referred to as end face 14a, and the other face on which the auxiliary electrode 5 is provided may be referred to as end face 14b.

[0012] 1, the distance from the mounting 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 inductor 1 has a length L of 2.0 mm, a width W of 2.0 mm to 6.0 mm, and a thickness T of 1.0 mm to 5.0 mm, for example.

[0013] FIG. 4 is a perspective view showing the internal configuration of the inductor 1. As shown in FIG. The element body 2 includes a conductor 20 and a core 30 having a substantially rectangular parallelepiped shape in which the conductor 20 is embedded, and is configured as a conductor-enclosed magnetic component in which the conductor 20 is enclosed in the core 30.

[0014] The base body 2 is a molded body that is compression-molded into an approximately rectangular parallelepiped shape by applying pressure and heat to a mixed powder of magnetic powder and resin that constitutes the core 30 and the conductor 20 while they are placed in a molding die.

[0015] In the mixed powder, for example, the amount of resin relative to the magnetic powder is about 3.1 wt %. In addition, the magnetic powder of this embodiment contains particles of two particle sizes: first magnetic particles which are large particles with a relatively large average particle size, and second magnetic particles which are small particles with a relatively small average particle size.During compression molding, the second magnetic particles, which are small particles, enter between the first magnetic particles, which are large, together with the resin, thereby increasing the filling rate of the core 30 and also increasing the magnetic permeability.

[0016] Here, the compounding ratio (weight ratio) of the first magnetic particles to the second magnetic particles is 70:30 to 85:15, preferably 70:30 to 80:20, and in this embodiment is 75:25. Furthermore, the ratio of the average particle size of the first magnetic particles to the average particle size of the second magnetic particles is preferably 5.0 or more. The magnetic powder may contain particles with an average particle size between the first magnetic particles and the second magnetic particles, so that the magnetic powder may contain particles of three or more particle sizes.

[0017] In this embodiment, the first and second magnetic particles are both particles having a metal particle and an insulating film covering the surface, and the metal particle is made of Fe-Si amorphous alloy powder, and the insulating film is made of zinc phosphate. By covering the metal particle with the insulating film, loss due to eddy current is reduced and the withstand voltage of the inductor is increased.

[0018] In addition, in the first magnetic particles, the metal particles may be Cr-free Fe-C-Si alloy powder, Fe-Ni-Al alloy powder, Fe-Cr-Al alloy powder, Fe-Si-Al alloy powder, Fe-Ni alloy powder, or Fe-Ni-Mo alloy powder.

[0019] In addition, in the first magnetic particles and the second magnetic particles, the insulating film may be made of other phosphates (magnesium phosphate, calcium phosphate, manganese phosphate, cadmium phosphate, etc.) or resin materials (silicone-based resins, epoxy-based resins, phenol-based resins, polyamide-based resins, polyimide-based resins, polyphenylene sulfide-based resins, etc.).

[0020] In the mixed powder of this embodiment, an epoxy resin containing bisphenol A type epoxy resin as a main component is used as the resin material. The epoxy resin may be a phenol novolac type epoxy resin. The resin material may be other than epoxy resin, and may be two or more types instead of one type. For example, in addition to epoxy resin, thermosetting resins such as phenol resin, polyester resin, polyimide resin, and polyolefin resin can be used as the resin material.

[0021] FIG. 5 is a diagram showing the configuration of the conductor 20. FIG. 5(a) is a plan view of the conductor 20 in FIG. 4 as viewed from the mounting surface 10 side (the side facing the top surface 12), and FIG. 5(b) is a front view of the conductor 20 in FIG. 4 as viewed from the end surface 14a side. FIG. 5(c) is a rear view of the conductor 20 as viewed from the end surface 14b side facing the end surface 14a, and FIG. 5(d) is a side view of the conductor 20 as viewed from the side surface 16 side in FIG. 4. In FIG. 5(b), the upper side is the mounting surface 10 side, and the lower side is the top surface 12 side. In FIG. 5(c), the upper side is the top surface 12 side, and the lower side is the mounting surface 10 side. In FIG. 5(d), the left side is the mounting surface 10 side, and the right side is the top surface 12 side.

[0022] In this embodiment, the conductor 20 is plate-shaped and has two conductor portions 21 extending inside the element body 2 between the pair of end faces 14 (see FIGS. 4 and 5(a)). In this embodiment, for example, the thickness of the conductor portions 21 is 0.1 mm or more and 0.4 mm or less, and the width is 0.5 mm or more and 1.0 mm or less.

[0023] The conductor 20 has two conductor portions 21, one end of each of which is bent toward the mounting surface 10, and each of the bent ends has a pair of main electrode portions 22 (the hatched portions shown in Figures 5(b) and 5(a) and indicated by the symbol "22") exposed from the same end face 14a to the mounting surface 10.

[0024] The conductor 20 has a shape in which the other ends of the two conductor portions 21 are bent toward the mounting surface 10. The conductor 20 has a connection portion 23 (the portion surrounded by the dotted rectangle in the drawing) that connects the other ends of the two conductor portions 21 to each other, and an auxiliary electrode portion 24 (the hatched portion shown and indicated by the reference numeral "24" in FIGS. 5(c) and 5(a)) that is provided on the connection portion 23 and exposed from the end face 14b and the mounting surface 10. In this embodiment, the auxiliary electrode portion 24 includes a part of the surface of the connection portion 23 (FIG. 5(c)).

[0025] In this embodiment, the conductor 20 has a length d1 in the direction along the conductor portion 21 in FIG. 5(a) that is equal to the length L of the element body 2. The width w1 of the conductor 20 in the front view in FIG. 5(b) and the width w2 of the conductor 20 in the rear view in FIG. 5(c) are smaller than the width W of the element body 2. As a result, in this embodiment, the conductor 20 can be embedded in the element body 2 so that the main electrode portion 22 of the conductor portion 21 and the auxiliary electrode portion 24 of the connection portion 23 are exposed at one end face 14a and the other end face 14b of the element body 2, respectively. As a result, the auxiliary electrode portion 24 is exposed from the mounting surface 10 of the element body 2 to the end face 14b.

[0026] The surface of the main electrode portion 22 exposed from the element body 2 is plated with nickel (Ni) and then tin (Sn), thereby forming the main electrode 4. The portion of the main electrode 4 that extends to the mounting surface 10 is electrically connected to the wiring of the circuit board by appropriate mounting means such as solder.

[0027] Similarly, the surface of the auxiliary electrode portion 24 exposed from the element body 2 is plated with nickel and then tin to form the auxiliary electrode 5 extending from the mounting surface 10 to the end surface 14b (see FIG. 3). The portion of the auxiliary electrode 5 extending to the mounting surface 10 is then joined to the conductor pattern of the circuit board by an appropriate mounting means such as solder.

[0028] In the inductor 1 having the above configuration, the conductor 20 is embedded in the element body 2 containing metal magnetic particles and resin, so the magnetic saturation characteristics do not decrease as the temperature increases more slowly than in conventional inductors that use ferrite as the core material. As a result, the inductor 1 can achieve a larger allowable current than conventional inductors that use ferrite cores.

[0029] Furthermore, in inductor 1, conductor 20 is embedded in element body 2, which is a molded body, so that the surfaces of main electrode portion 22 and auxiliary electrode portion 24 of conductor 20 can be easily exposed so as to be flush with the surface of element body 2. Therefore, in inductor 1, the mounting area of ​​inductor 1 on a circuit board can be made smaller than in a configuration in which a conductor is sandwiched between two ferrite cores.

[0030] Furthermore, in inductor 1, auxiliary electrode portion 24 is formed so as to include part of the surface of connection portion 23, which allows the shape of conductor 20 to be simplified compared to conductor 20a of the second embodiment and conductor 20b of the third embodiment, which will be described later. Furthermore, auxiliary electrode portion 24 is arranged in a position where it is exposed from mounting surface 10 to end face 14b of element body 2. Therefore, for example, when conductor 20 is placed in a molding die for element body 2 during manufacturing of inductor 1, main electrode portion 22 and auxiliary electrode portion 24 of conductor 20 are almost in contact with the wall of the molding die, and therefore conductor 20 can be compression molded with a stable posture in the molding die, thereby improving manufacturing yield.

[0031] [2. Second Embodiment] Next, an inductor 1a according to a second embodiment of the present invention will be described. The inductor 1a has a similar configuration to the inductor 1 according to the first embodiment, but differs in that it has a conductor 20a instead of the conductor 20. As a result, the inductor 1a has an auxiliary electrode 5a instead of the auxiliary electrode 5. The auxiliary electrode 5a is located at a different position on the surface of the element body 2 from the auxiliary electrode 5.

[0032] 6 and 7 are perspective views of the end faces 14a and 14b of the inductor 1a, respectively, as viewed from the mounting surface 10, and correspond to FIGS. 2 and 3 of the inductor 1 according to the first embodiment. FIG. 8 is a diagram showing the configuration of a conductor 20a, and corresponds to FIG. 5, which shows the configuration of the conductor 20 of the inductor 1 described above. Similar to FIG. 5, (a) of FIG. 8 is a plan view of the conductor 20a as viewed from the mounting surface 10, and (b) of FIG. 8 is a front view of the conductor 20a as viewed from the end face 14a. (c) of FIG. 8 is a back view of the conductor 20a as viewed from the end face 14b opposite the end face 14a, and (d) of FIG. 8 is a side view of the conductor 20a as viewed from the side of the side face 16.

[0033] Of the components shown in Figures 6, 7, and 8, the same components as those of the inductor 1 according to the first embodiment described above will be indicated using the same symbols as those in Figures 2, 3, and 5, and the explanations given for Figures 2, 3, and 5 above will be used.

[0034] The conductor 20a has a configuration similar to that of the conductor 20 according to the first embodiment, but differs in that it includes a conductor portion 21a instead of the conductor portion 21. As with the conductor portion 21, one end of the pair of conductor portions 21a is connected to each other by a connection portion 23a (the portion surrounded by the dotted rectangle in the figure). However, the length of the conductor portion 21a is shorter than that of the conductor portion 21. As a result, the connection portion 23a of the conductor 20a is enclosed within the element body 2.

[0035] Conductor 20a also differs from conductor 20 in that it has auxiliary electrode portion 24a instead of auxiliary electrode portion 24. Unlike auxiliary electrode portion 24, auxiliary electrode portion 24a does not include the surface of connecting portion 23a, and is formed as two portions extending from connecting portion 23a, as shown in FIGS. 8(a) and 8(c). Furthermore, in conductor 20a, the distance w3 between the outer side surfaces of the two auxiliary electrode portions 24a is equal to the width W of element body 2. As a result, each of the two auxiliary electrode portions 24a is exposed from mounting surface 10 to side surface 16 of element body 2.

[0036] The surface of the auxiliary electrode portion 24a exposed from the element body 2 is plated with nickel and then tin, thereby forming the auxiliary electrode 5a extending from the mounting surface 10 to the side surface 16 (see FIG. 7). The portion of the auxiliary electrode 5a extending to the mounting surface 10 is then joined to a conductor pattern on the circuit board by an appropriate mounting means such as solder.

[0037] As described above, because the length d2 of the conductor 20a is shorter than the length L of the element body 2, in the inductor 1a, the main electrode portion 22 is exposed from the end face 14a of the element body 2 and forms the main electrode 4, while the connection portion 23a is not exposed from the end face of the element body 2 and is contained within the element body 2. This allows the inductor 1a to obtain a larger inductance than the inductor 1.

[0038] The auxiliary electrode portion 24a is also formed so as to be exposed from the mounting surface 10 to the side surface 16 of the element body 2. This makes it possible to stabilize the posture of the conductor 20a when placing it in a mold for the element body 2 during the manufacture of the inductor 1, for example, and improve the manufacturing yield.

[0039] Furthermore, since the auxiliary electrode portion 24a forms the auxiliary electrode 5a over the side surface 16, when the inductor 1a is mounted on a circuit board by soldering, a solder fillet is also formed on the portion of the auxiliary electrode 5a that extends to the side surface 16, making it easy to determine whether the soldering is successful by, for example, visual inspection or image inspection.

[0040] 3. Third Embodiment Next, an inductor 1b according to a third embodiment of the present invention will be described. The inductor 1b has a similar configuration to the inductor 1a according to the second embodiment, but differs in that it has a conductor 20b instead of the conductor 20a. As a result, the inductor 1b has an auxiliary electrode 5b instead of the auxiliary electrode 5a. The auxiliary electrode 5b is located at a different position on the surface of the element body 2 from the auxiliary electrode 5a.

[0041] 9 and 10 are perspective views of the end faces 14a and 14b of the inductor 1b, respectively, as viewed from the mounting surface 10, and correspond to FIGS. 6 and 7 for the inductor 1a according to the second embodiment. FIG. 11 is a diagram showing the configuration of a conductor 20b, and corresponds to FIG. 8 showing the configuration of the conductor 20a of the inductor 1a described above. Similar to FIG. 8, FIG. 11(a) is a plan view of the conductor 20b as viewed from the mounting surface 10, and FIG. 11(b) is a front view of the conductor 20b as viewed from the end face 14a. FIG. 11(c) is a back view of the conductor 20b as viewed from the end face 14b opposite the end face 14a, and FIG. 11(d) is a side view of the conductor 20b as viewed from the side of the side face 16.

[0042] Of the components shown in Figures 9, 10, and 11, the same components as those of the inductor 1a according to the second embodiment described above will be indicated using the same symbols as those in Figures 6, 7, and 8, and the explanations given for Figures 6, 7, and 8 above will be used.

[0043] The conductor 20b has a configuration similar to that of the conductor 20a according to the second embodiment, but differs in that it has an auxiliary electrode portion 24b instead of the auxiliary electrode portion 24a.

[0044] The auxiliary electrode portion 24b is formed on two extension portions 25 extending from the connection portion 23a. The auxiliary electrode portion 24b, which is the surface of each of the extension portions 25, is exposed from the mounting surface 10 to the end surface 14b of the element body 2. However, in this embodiment, the conductor 20b has a distance w4 between the outer side surfaces of the two auxiliary electrode portions 24b, which is shorter than the width W of the element body 2. As a result, the two auxiliary electrode portions 24b are not exposed on the side surface 16 of the element body 2.

[0045] Similar to auxiliary electrode portion 24a, auxiliary electrode portion 24b is nickel-plated and tin-plated on the portion exposed from element body 2, thereby forming auxiliary electrode 5b extending from mounting surface 10 to end face 14b of element body 2 (see FIG. 10). The portion of auxiliary electrode 5b extending to mounting surface 10 is then joined to a conductor pattern on a circuit board by appropriate mounting means such as solder.

[0046] In inductor 1b, auxiliary electrode portion 24b is formed on extension portion 25 extending from connection portion 23a, so that auxiliary electrode 5b can have a larger area than auxiliary electrode 5a. Therefore, in inductor 1b, the bonding strength with the circuit board can be increased compared to inductor 1a.

[0047] All of the above-described embodiments are merely examples of aspects of the present invention, and any modifications and applications are possible without departing from the spirit 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.

[0048] 4. Configurations supported by the above embodiments The above-described embodiment and modifications support the following configurations.

[0049] (Configuration 1) An inductor comprising: an element body containing metal magnetic particles and a resin; and a conductor embedded in the element body, wherein the element body has a mounting surface facing the mounting board when mounted, a pair of end faces perpendicular to the mounting surface, and a pair of side surfaces perpendicular to the mounting surface and the pair of end faces; the conductor is plate-shaped and has two conductor portions extending inside the element body between the pair of end faces; a pair of main electrode portions provided at one end of each of the two conductor portions and exposed from the same one end face to the mounting surface; a connection portion connecting the other ends of the two conductor portions to each other; and an auxiliary electrode portion provided at the other ends of the two conductor portions and exposed from the mounting surface. According to the inductor of Configuration 1, a plate-shaped conductor is enclosed inside an element body containing metal magnetic particles and resin, so that a large current inductor with a larger allowable current and low inductance can be provided.

[0050] (Configuration 2) The inductor according to configuration 1, wherein the auxiliary electrode portion includes a portion of the surface of the connection portion and is exposed from the mounting surface to the other end face opposite the one end face of the element body. According to the inductor of configuration 2, the auxiliary electrode portion is formed as part of the surface of the connection portion and is arranged in a position where it is exposed from the mounting surface to the end surface. This simplifies the shape of the conductor and, for example, stabilizes the posture of the conductor when placing it in a molding die for the element body, thereby improving the manufacturing yield.

[0051] (Configuration 3) The inductor according to configuration 1, wherein the connection portion is included in the element body, and the auxiliary electrode portion extends from the connection portion and is exposed on a mounting surface of the element body. According to the inductor of Configuration 3, the connection portion is contained within the element body, so that a larger inductance can be easily achieved.

[0052] (Configuration 4) The inductor according to configuration 3, wherein the auxiliary electrode portion extends from the connection portion and extends from the mounting surface of the element body to the side surface. According to the inductor of configuration 4, in addition to the configuration of configuration 3, the end and side surfaces of the convex portion, which is the auxiliary electrode portion, are arranged at the mounting surface and side surface of the element body, so that, for example, the posture of the conductor when placing the conductor in a molding die for the element body can be stabilized, improving manufacturing yield and easily realizing a larger inductance.

[0053] (Configuration 5) An inductor according to configuration 1, wherein the connection portion is contained within the element body, and the auxiliary electrode portion extends from the connection portion and is exposed from the mounting surface to the other end face opposite the one end face of the element body. According to the inductor of configuration 5, in addition to the configuration of configuration 3, the auxiliary electrode portion is configured as an extension portion extending from the connection portion, so that the area of ​​the extension portion can be made large, thereby increasing the bonding strength with the circuit board and easily achieving a larger inductance. [Explanation of symbols]

[0054] 1, 1a, 1b... inductor, 2... element body, 4... main electrode, 5... auxiliary electrode, 10... mounting surface, 12... upper surface, 14... end surface, 16... side surface, 20, 20a, 20b... conductor, 21, 21a... conductor portion, 22... main electrode portion, 23, 23a... connection portion, 24, 24a, 24b... auxiliary electrode portion, 25... extension portion, 30... core.

Claims

1. An inductor comprising: an element body containing metal magnetic particles and a resin; and a conductor embedded in the element body, the element body has a mounting surface that faces a mounting substrate during mounting, a pair of end surfaces that are perpendicular to the mounting surface, and a pair of side surfaces that are perpendicular to the mounting surface and the pair of end surfaces; The conductor is It is plate-shaped, two conductor portions extending through the element body between the pair of end faces; a pair of main electrode portions provided at one end of each of the two conductor portions and exposed from the end face of the same conductor portion to the mounting surface; a connecting portion that connects the other ends of the two conductor portions to each other; an auxiliary electrode portion provided at the other end of each of the two conductor portions and exposed from the mounting surface; having Inductor.

2. the auxiliary electrode portion includes a part of a surface of the connection portion and is exposed from the mounting surface to the other end face opposite to the one end face of the element body.

10. The inductor of claim 1.

3. the connecting portion is included in the element body, the auxiliary electrode portion extends from the connection portion and is exposed on the mounting surface of the element body.

10. The inductor of claim 1.

4. the auxiliary electrode portion extends from the connection portion and extends from the mounting surface to the side surface of the element body; 4. The inductor according to claim 3.

5. the connecting portion is included in the element body, the auxiliary electrode portion extends from the connection portion and is exposed from the mounting surface to the other end face opposite the one end face of the element body.

10. The inductor of claim 1.

Images