JP6631391B2 - Coil device - Google Patents

Description

  The present invention relates to a coil device used as an inductor element or the like.

  2. Description of the Related Art Various coil devices are mounted on various electronic and electrical devices as inductor elements and the like. For example, as an example of such a coil device, a coil device disclosed in Patent Document 1, for example, has been developed. In the coil device disclosed in Patent Literature 1, cracks that may occur inside the center of the coil are prevented by devising the cross-sectional shape of the coil.

  However, in the related art, there is an inconvenience that a crack generated on the outer surface on the non-mounting side of the core portion in which the coil is built cannot be prevented. In particular, in the case of a coil device used in a high-temperature environment such as an engine room of an automobile, for example, a stress due to thermal expansion of the substrate is provided on the mounting side outer surface of the core portion mounted on the circuit board. Has a problem that cracks easily occur on the outer surface of the core portion on the mounting side.

JP 2012-89595 A

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a coil device capable of preventing occurrence of cracks.

In order to achieve the above object, a coil device according to the present invention includes:
A winding portion in which the wire is coiled,
A core portion containing a magnetic material and a resin, and covering the entire winding portion including the inside of the winding portion;
A terminal electrode mounted on the mounting-side outer surface of the core portion located at one end of the winding portion in the winding axis direction, a coil device having:
The content of the resin contained in the first region of the core portion including at least the central portion of the mounting-side outer surface is at least the central portion of the non-mounting-side outer surface of the core portion located on the side opposite to the mounting-side outer surface. The content is larger than the content of the resin contained in the second region of the core portion.

  In the coil device according to the present invention, the content of the resin contained in the first region of the core portion including at least the central portion of the outer surface on the mounting side is larger than that on the outer surface on the non-mounting side. For this reason, a resin-rich layer is formed on the mounting-side outer surface of the core portion, and the resin-rich layer serves as a stress relaxation layer, thereby suppressing the occurrence of cracks.

  According to the present invention, particularly in the case of a coil device exposed to a high-temperature environment such as an engine room of an automobile or a power machine, even if the circuit board thermally expands, cracks are less likely to occur on the outer surface on the mounting side. Conventionally, cracks are likely to occur in the core portion on the outer surface on the mounting side under the influence of, for example, thermal expansion of the substrate exposed to a high temperature environment. According to the present invention, a resin-rich layer is formed on the mounting-side outer surface of the core portion even when affected by, for example, thermal expansion of a substrate exposed to a high-temperature environment, and the resin-rich layer serves as a stress relaxation layer. , To suppress the occurrence of cracks.

  The second region may exist continuously inside and outside the winding part.

  Inside the core portion, between the first region and the second region along the winding axis direction, the content of the resin in the first region is different, and the content of the resin in the second region is different. A third region in which the resin is contained at a content different from the content may be present.

  The third region may be present continuously inside and outside the winding part. When the third region contains the resin in a smaller content than the resin content of the first region, the magnetic material is relatively increased, and the magnetic characteristics are improved. When the third region contains the resin in a smaller content than the resin content of the second region, the magnetic material is relatively increased, and the magnetic characteristics are further improved. When the third region contains a resin at a higher content than the second region, the third region also becomes a resin-rich layer as compared with the second region, and the stress relaxation characteristics are improved.

  The first region may have a protrusion protruding toward the second region inside the winding portion. By arranging the convex portion inside the winding portion, the positioning of the winding portion becomes possible.

FIG. 1 is a perspective view of a coil device according to an embodiment of the present invention. FIG. 2A is a cross-sectional view of the coil device shown in FIG. FIG. 2B is a sectional view of a coil device according to another embodiment of the present invention. FIG. 2C is a sectional view of a coil device according to still another embodiment of the present invention. FIG. 2D is a sectional view of a coil device according to still another embodiment of the present invention. FIG. 2E is a sectional view of a coil device according to still another embodiment of the present invention. FIG. 2F is a sectional view of a coil device according to still another embodiment of the present invention. FIG. 2G is a sectional view of a coil device according to still another embodiment of the present invention. FIG. 3A is a cross-sectional view illustrating a manufacturing process of the coil device illustrated in FIG. 1, and FIG. 3B is a cross-sectional view illustrating a manufacturing process subsequent to FIG. 3A.

First Embodiment As shown in FIG. 1 and FIG. 2A, an inductor element 2 as a coil device according to an embodiment of the present invention includes a core 4 as a compression molded body, and a coiled wire inside the core 4. 6a is wound. The wire 6a is composed of, for example, a conductive wire and, if necessary, an insulating coating layer covering the outer periphery of the conductive wire.

  The conductor is made of, for example, Cu, Al, Fe, Ag, Au, phosphor bronze, or the like. The insulating coating layer is made of, for example, polyurethane, polyamide imide, polyimide, polyester, polyester-imide, polyester-nylon, or the like. The cross-sectional shape of the wire 6a is not particularly limited, and examples thereof include a circular shape and a rectangular shape.

  The core part 4 is formed by compression molding or injection molding of granules containing a magnetic powder and a binder. The magnetic powder is not particularly limited, but may be Sendust (Fe-Si-Al; iron-silicon-aluminum), Fe-Si-Cr (iron-silicon-chromium), permalloy (Fe-Ni), carbonyl iron, Metallic magnetic powders such as carbonyl Ni-based powders, amorphous powders, and nanocrystal powders are preferably used.

  However, the magnetic powder may be a ferrite magnetic powder such as Mn-Zn or Ni-Cu-Zn. The binder resin is not particularly limited, but examples thereof include an epoxy resin, a phenol resin, an acrylic resin, a polyester resin, a polyimide, a polyamideimide, a silicone resin, and a combination thereof.

  As shown in FIG. 2A, the winding portion 6 is a portion in which one or more wires 6a are wound in a coil shape, and from the winding portion 6, at least a pair of lead portions 6b at both ends of the wire 6a are formed. , Are drawn out of the core portion 4. In the illustrated embodiment, a pair of lead portions 6b is pulled out from the winding portion 6 along the Z-axis direction from a mounting-side outer surface 4A of the core portion 4 and is connected to a pair of terminal electrodes 8 provided on the outer surface 4A. , Welding or conductive adhesive respectively.

  In the present embodiment, each terminal electrode 8 is formed only on the mounting-side outer surface 4A of the core portion 4, but has an electrode side portion 8a formed continuously up to the side surface 4C of the core portion 4. You may. The terminal electrode 8 is not particularly limited, and may be a metal terminal such as copper or a copper alloy adhered to the core portion 4, or a baked electrode containing silver or a silver alloy, or formed by plating or the like. It may be a metal film electrode.

  In the present embodiment, the lower surface of the core portion 4 is a mounting-side outer surface 4A connected to a circuit board or the like, and is formed substantially parallel to a plane passing through mutually perpendicular X-axis and Y-axis. The winding axis of No. 6 is substantially parallel to a Z axis perpendicular to a plane passing through the X axis and the Y axis. In the present embodiment, the upper surface of the core portion 4 is the non-mounting outer surface 4B substantially parallel to the lower surface, and the four side surfaces 4C are substantially perpendicular to the upper surface and the lower surface. However, the shape of the core portion 4 is not particularly limited, and is not limited to a hexahedron, and may be a cylindrical shape, an elliptical column, a polygonal column, or the like.

  The size of the inductor element 2 of the present embodiment is not particularly limited. For example, the X-axis direction width X0 is 1.0 to 20 mm, the Y-axis direction width Y0 is 1.0 to 20 mm, and the height Z0 is 1.0 to 10 mm. It is. The inductor element 2 is, for example, an element such as a DC / DC converter exposed to a high temperature environment such as an engine room of an automobile, a choke coil in a power supply line, a decoupling element in a power supply line, and an impedance matching element. It can be used as an element, a constituent element of a filter, an antenna element, or the like.

  As shown in FIG. 2A, in the present embodiment, the core portion 4 is configured such that the inner peripheral portion, the outer peripheral portion, and both ends of the winding shaft of the winding portion 6 are integrated to cover the entirety. The core portion 4 includes a first region 4a including at least a central portion of the mounting-side outer surface 4A, and a second region 4b including at least a central portion of the non-mounting-side outer surface 4B. In the present embodiment, the central portion means an inner portion of the winding portion 6.

  In the present embodiment, the first region 4a is located further below the lower end in the Z-axis direction of the winding portion 6 and includes the base portion 4a1 including the entire mounting-side outer surface 4A, and is continuous from the central portion of the base portion 4a1. And a projection 4a2 projecting in a mountain shape along the Z-axis direction in the direction of the outer surface 4B opposite to the mounting side. The base portion 4a1 forms a mounting-side outer surface 4A and lower portions of four side surfaces 4C of the core portion 4.

  The second region 4b is located further above the upper end of the winding portion 6 in the Z-axis direction and includes a base portion 4b1 including the entire non-mounting-side outer surface 4B, and a mounting-side outer surface continuously from the center of the base portion 4b1. A projection 4b2 protruding along the Z-axis direction in the direction of 4A. The convex portion 4b2 has a shape that fills a gap between the convex portion 4a2 projecting in a mountain shape and the inner peripheral surface of the winding portion 6. The second region 4b has an outer peripheral portion 4b3 that continuously projects from the base portion 4b1 at the outer peripheral portion of the winding portion 6 in the direction of the mounting-side outer surface 4A along the Z-axis direction. The outer peripheral part 4b3 forms the upper part of the four side surfaces 4C of the core part 4. The mixture of the magnetic powder and the binder resin constituting the second region 4b is also filled in the gap between the wires 6a constituting the winding portion 6.

  The thickness Z1 of the base portion 4a1 in the first region 4a in the Z-axis direction is preferably 10 to 40% of the height Z0 of the core portion 4, and the thickness Z2 of the base portion 4b1 of the second region 4b in the Z-axis direction. , But not necessarily. The height Z1a of the protrusion 4a2 may be lower or higher than the height Z3 of the winding portion 6 in the Z-axis direction, preferably 20 to 120% of the height Z3, more preferably 50 to 100%. %% as high. Further, the projection 4a2 is preferably in the shape of a truncated cone. This is because the protrusions 4a2 can be easily formed, the protrusions 4a2 can easily enter the inside of the winding portion 6 as the air-core coil, and a positioning effect can be obtained.

In the present embodiment, the first region 4a and the second region 4b constituting the core portion 4 are in direct contact at a predetermined interface, and both include the magnetic powder and the binder resin. The amount (content of magnetic powder) is different. That is, the content of the binder resin contained in the first region 4a is larger than the content of the binder resin contained in the second region 4b. For example, when the content of the binder resin contained in the second region 4b is 1 to 11 parts by mass with respect to 100 parts by mass of the magnetic powder, the content of the binder resin contained in the first region 4a becomes the second region. It is preferable that the content is 1.1 to 2.0 times the content of the binder resin contained in the region 4b.

  The core body 4 composed of the first region 4a and the second region 4b preferably contains a magnetic powder as a magnetic material in an amount of 90 to 99% by mass based on the total mass of the core body 4. In addition to the magnetic powder and the binder resin, a solvent, a plasticizer, a lubricant, an antioxidant, a flame retardant, a heat stabilizer, and the like may be contained in the core body 4.

  Next, a method of manufacturing the inductor element 2 shown in FIGS. 1 and 2A will be described. First, a first region 4a shown in FIG. 3A is formed, for example, in a cavity of a mold. In the first region 4a, a mountain-shaped convex portion 4a2 is formed. The first region 4a contains at least a magnetic powder and a binder resin.

  Next, as shown in FIG. 3B, the winding part 6 is set on the base part 4a1 such that the projection 4a2 enters the inside of the winding part 6 as an air core coil. At this time, the inner peripheral part of the lower end of the winding part 6 is self-aligned with the obtuse boundary between the convex part 4a2 and the base part 4a1. Since the convex portion 4a2 has a truncated cone shape, the winding portion 6 can be easily positioned and installed at the center of the first region 4a on the base portion 4a1.

  After that, a mixture containing the magnetic powder and the binder resin constituting the second region 4b shown in FIG. 2A (containing less resin than the first region 4a) is filled in the cavity, and the whole is heated and compressed. Thus, the inductor element 2 shown in FIGS. 1 and 2A is obtained. The heating temperature during the heat compression is preferably 50 to 300 ° C., and the compression pressure is preferably 1 to 400 Pa. As a method for compression molding, a mold may be used, or hydraulic pressure or water pressure may be used. Although illustration of the lead portion 6b from the winding portion 6 is omitted in FIG. 3, after the molding, the lead portion 6b is taken out together with the molded body. Thereafter, the terminal electrode 8 is formed on the mounting-side outer surface 4A of the core body 4 by using plating or a conductive paste so as to be connected to the lead portion 6b.

  In this embodiment, the magnetic powder is metal magnetic particles, and the outer periphery of the particles is preferably coated with an insulating film. Examples of the insulating film include a metal oxide film and a resin film. The particle size of the magnetic powder is preferably 0.5 to 50 μm.

  In the inductor element 2 according to the present embodiment, the content of the resin contained in the first region 4a of the core portion 4 including at least the central portion of the mounting-side outer surface 4A is larger than that of the non-mounting-side outer surface 4B. . For this reason, on the outer surface 4B on the non-mounting side of the core portion 4, a resin-rich layer including the base portion 4b1, the convex portion 4b2, and the outer peripheral portion 4b3 is formed, and the resin-rich layer serves as a stress relaxation layer, thereby suppressing the occurrence of cracks. I do.

  In the inductor element 2 according to the present embodiment, cracks are unlikely to occur on the outer surface on the mounting side even when the circuit board thermally expands, particularly when exposed to a high temperature environment, such as inside an automobile engine room or a power machine. Become. Conventionally, for example, when the substrate is exposed to a high temperature environment due to thermal expansion or the like, the core portion on the outer surface on the mounting side is moved from the outer surface 4A on the mounting side toward the inside of the winding portion 6. Spreading cracks 10 (see FIG. 2A) are likely to occur. In the present embodiment, a resin-rich layer is formed on the mounting-side outer surface 4A of the core portion 4 even if the resin-rich layer is affected by, for example, thermal expansion of the substrate exposed to a high-temperature environment. It becomes a relaxation layer and suppresses generation of cracks.

Second Embodiment As shown in FIG. 2B, an inductor element 2a according to the present embodiment has a first region 4a formed of only a flat base portion 4a1 except that it has no convex portion. This is the same as the inductor element 2 of the first embodiment, and a duplicate description will be omitted. In the present embodiment, the inside of the winding portion 6 is filled only with the inner peripheral portion 4b2 of the second region 4b. The inductor element 2A of the present embodiment has the same operation and effect as the inductor element 2 except that the inductor element 2A of the first embodiment does not have the protrusion 4a2 in the core 4 of the inductor element 2 of the first embodiment.

Third Embodiment As shown in FIG. 2C, an inductor element 2b according to the present embodiment is the same as the inductor element of the first embodiment except that the shape and height of the protrusions 4a2 formed in the first region 4a are different. 2, and a duplicate description is omitted. In the present embodiment, the convex portion 4a2 has a columnar shape instead of a truncated cone shape, and the height thereof is set lower than the convex portion 4a2 of the inductor element 2. For example, in the present embodiment, the height Z1a of the projection 4a2 is preferably 0 to 40% of the height Z3 of the winding portion 6.

  The inductor element 2b of the present embodiment has the same operation and effect as the inductor element 2 except that the inductor element 2b of the first embodiment has a convex part 4a2 having a different shape and height from the convex part 4a2 of the core part 4 of the inductor element 2 of the first embodiment. .

Fourth Embodiment As shown in FIG. 2D, the inductor element 2c according to the present embodiment also includes an outer peripheral portion protruding from the base portion 4a1 toward the non-mounting side surface 4B along the Z-axis direction in the first region 4a. Except that 4a3 is formed, it is the same as the inductor element 2 of the first embodiment, and duplicate description will be omitted. In the present embodiment, the outer peripheral portion 4a3 of the first region 4a forms a part of the four side surfaces 4C, and the outer peripheral portion 4b3 of the second region 4b is located inside. The height of the outer peripheral portion 4a3 in the Z-axis direction is substantially the same as the height of the convex portion 4a2 in the Z-axis direction, but may be different. The inductor element 2c of the present embodiment has the same operation and effect as the inductor element 2 except that the outer peripheral portion 4a3 is formed integrally with the first region 4a of the core portion 4.

Fifth Embodiment As shown in FIG. 2E, an inductor element 2d according to the present embodiment is similar to the first embodiment except that a third region 4c is formed between a first region 4a and a second region 4b. This is the same as the inductor element 2 of the embodiment, and a duplicate description will be omitted. In the present embodiment, the second region 4b is composed of only the flat base portion 4b1, and the space between the second region 4b and the first region 4a is filled with the third region 4c.

  The third region 4c fills a gap between the first region 4a and the winding portion 6 inside the winding portion 6 and an inner periphery that fills a gap between the first region 4a and the second region 4b. A portion 4c2 and an outer peripheral portion 4c3 located outside the winding portion 6 in the radial direction are also filled in the gap between the wires 6a, and are continuously present inside and outside the winding portion 6. ing. When the third region 4c contains a resin with a smaller content than the resin content of the first region 4a, the magnetic powder relatively increases, and the magnetic characteristics are improved. When the third region 4c contains a resin at a lower content than the resin content of the second region 4b, the magnetic powder becomes relatively large, and the magnetic characteristics are further improved. When the third region 4c contains a resin at a higher content than the resin content of the second region 4b, the third region 4c also becomes a resin-rich layer as compared with the second region 4b, and the stress relaxation characteristics are improved. I do. In addition, since the third region 4c is a portion that is filled between the wires 6a constituting the winding portion 6, it is preferable that the third region 4c has a material composition that easily enters between the wires 6a.

Sixth Embodiment As shown in FIG. 2F, an inductor element 2e according to the present embodiment is different from the inductor element 2e shown in FIG. 2B in that a third region 4c is formed between a first region 4a and a second region 4b. This is the same as the inductor element 2a of the second embodiment shown, and a duplicate description will be omitted. In the present embodiment, the second region 4b is composed of only the flat base portion 4b1, and the space between the second region 4b and the first region 4a is filled with the third region 4c.

  The third region 4c has an inner peripheral portion 4c2 that fills a gap inside the winding portion 6, and an outer peripheral portion 4c3 located outside the winding portion 6 in the radial direction, and also fills a gap between the wires 6a. And exist continuously inside and outside the winding portion 6. When the third region 4c contains a resin with a smaller content than the resin content of the first region 4a, the magnetic powder relatively increases, and the magnetic characteristics are improved. When the third region 4c contains a resin at a lower content than the resin content of the second region 4b, the magnetic powder becomes relatively large, and the magnetic characteristics are further improved. When the third region 4c contains a resin at a higher content than the resin content of the second region 4b, the third region 4c also becomes a resin-rich layer as compared with the second region 4b, and the stress relaxation characteristics are improved. I do. In addition, since the third region 4c is a portion that is filled between the wires 6a constituting the winding portion 6, it is preferable that the third region 4c has a material composition that easily enters between the wires 6a.

Seventh Embodiment As shown in FIG. 2G, an inductor element 2f according to the present embodiment differs from FIG. 2C in that a third region 4c is formed between a first region 4a and a second region 4b. This is the same as the inductor element 2b of the third embodiment shown, and a duplicate description will be omitted. In the present embodiment, the second region 4b is composed of only the flat base portion 4b1, and the space between the second region 4b and the first region 4a is filled with the third region 4c.

  The third region 4c has an inner peripheral portion 4c2 that fills a gap inside the winding portion 6, and an outer peripheral portion 4c3 located outside the winding portion 6 in the radial direction, and also fills a gap between the wires 6a. And exist continuously inside and outside the winding portion 6. When the third region 4c contains a resin with a smaller content than the resin content of the first region 4a, the magnetic powder relatively increases, and the magnetic characteristics are improved. When the third region 4c contains a resin at a lower content than the resin content of the second region 4b, the magnetic powder becomes relatively large, and the magnetic characteristics are further improved. When the third region 4c contains a resin at a higher content than the resin content of the second region 4b, the third region 4c also becomes a resin-rich layer as compared with the second region 4b, and the stress relaxation characteristics are improved. I do. In addition, since the third region 4c is a portion that is filled between the wires 6a constituting the winding portion 6, it is preferable that the third region 4c has a material composition that easily enters between the wires 6a.

  Note that the present invention is not limited to the above-described embodiments, and can be variously modified within the scope of the present invention.

  For example, in the above-described embodiment, the core portion 4 includes the first region 4a and the second region 4b, or the third region 4c is disposed therebetween. However, the third region 4c of the core portion 4 does not need to be a single region, and may be divided into a plurality of regions having different binder resin contents.

  Further, in the above-described embodiment, after the first region 4a is filled and formed, the winding part 6 is attached and the second region 4b is filled, but the reverse is also possible. That is, after the second region 4b is filled and formed upside down in the Z-axis direction, the winding part 6 may be attached and the first region 4a may be filled. In that case, a protrusion similar to the protrusion 4a2 formed in the center of the first region 4a may be formed in the second region 4b to position the winding portion 6.

  Further, in the above-described embodiment, the lead portion 6b of the winding portion 6 is directly drawn out toward the outer surface 4A on the mounting side. However, the present invention is not limited to this. It may be connected to the unit 8a. Alternatively, the lead portion 6b may be drawn out of the core portion 4 toward the side surface 4C, then extended to the mounting-side outer surface 4A, and connected to the terminal electrode 8.

  Furthermore, in the above-described embodiment, the winding portion 6 is used in which the inner diameter and the outer diameter of the winding portion 6 are uniform along the Z-axis direction which is the winding axis direction. The shape is not particularly limited. For example, along the outer peripheral surface of the chevron-shaped projection 4a2 shown in FIG. 2A, the truncated body-shaped winding portion 6 may be such that the inner diameter and the outer diameter become smaller toward the upper part in the Z-axis direction. Other shapes may be used.

2, 2a to 2f ... Inductor element (coil device)
4 core part 4a first region 4a1 base part 4a2 convex part 4a3 outer peripheral part 4b second region 4b1 base part 4b2 inner peripheral part 4b3 outer peripheral part 4c third region 4c2 inner peripheral part 4c3 ... Outer peripheral part 4A ... Mounting side outer surface 4B ... Non-mounting side outer surface 4C ... Side surface 6 ... Winding part 6a ... Wire 6b ... Lead part 8 ... Terminal electrode 8a ... Electrode side part 10 ... Crack

Claims (6)

A winding portion in which the wire is coiled,
A core portion containing a magnetic material and a resin, and covering the entire winding portion including the inside of the winding portion;
A terminal electrode mounted on the mounting-side outer surface of the core portion located at one end of the winding portion in the winding axis direction, a coil device having:
The core part is
A first region including at least a central portion of the outer surface on the mounting side;
A second region including at least a central portion of the non-mounting side outer surface located on the opposite side to the mounting side outer surface,
The content of the resin contained in the second region is 1 to 11 parts by mass with respect to 100 parts by mass of the magnetic material,
The content of the resin contained in the first region is more than the content of the resin contained in the second region,
The coil device , wherein the content of the resin included in the first region is 1.1 to 2.0 times the content of the resin included in the second region . The first region includes a mounting-side base portion, and the second region includes a mounting-side base portion,
The thickness (Z1) in the height direction of the base portion included in the first region and the thickness (Z2) in the height direction of the base portion included in the second region are substantially the same. The coil device according to claim 1, wherein the height is 0.1 to 0.4 times the height (Z0) of the core portion. The second region, the coil device according to claim 1 or 2 are present continuously inside and outside of the winding portion. Inside the core portion, between the first region and the second region along the winding axis direction, the content of the resin in the first region is different, and the content of the resin in the second region is different. The coil device according to claim 1, wherein there is a third region in which the resin is contained at a content different from the content. The coil device according to claim 4 , wherein the third region is continuously provided inside and outside the winding portion. The coil device according to any one of claims 1 to 5 , wherein the first region has a protrusion protruding toward the second region inside the winding part.