JPH04361506A - Inductor - Google Patents

Abstract

PURPOSE:To obtain a small type and highly reliable inductor. CONSTITUTION:A magnetic body is formed by a plurality of second magnetic bodies, and a conductor (coil) 2 is arranged in the magnetic body. The above- mentioned magnetic bodies are formed into a magnetic green compact 3 by adding the prescribed powder bonding agent to the magnetic powder, and a magnetic body is formed by junctioning a plurality of magnetic bodies with a high permeability bonding agent. As the magnetic green compacts 3 are junctioned with each other by a high permeability bonding agent, a highly strong junction can be accomplished, and a highly reliable small type inductor can be obtained without formation of a magnetic gap.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to inductors used in electronic circuits and the like.

0002

[Prior Art] First, Fig. 5 shows this type of inductor.
Explain with reference to. Generally, in a closed magnetic circuit type inductor, a coil is wound around a winding bobbin to form a coil bobbin 16 having terminal electrodes at both ends.
Insert the ferrite EE type core 17 etc. into the core 17.
The core 17 is joined by sandwiching the divided core 17 from the outside by core holding metal plates 15 having spring properties.

0003

[Problems to be Solved by the Invention] Incidentally, in inductors, adhesives are often used to bond the cores together, and as a result, the adhesive layer not only remains at the bonding interface, but also creates a magnetic gap. The adhesive layer is affected by humidity. In order to avoid such problems, as mentioned above, a core holding metal plate is used to join the cores together, but the problem is that the core holding metal plate increases the size of the inductor. There is. SUMMARY OF THE INVENTION An object of the present invention is to provide an inductor that is compact and can provide large inductance and impedance, that is, a compact inductor that can provide high reliability.

0004

[Means for Solving the Problems] In the present invention, a compacted powder body obtained by pressure-molding a magnetic powder body in which a magnetic core material (magnetic powder) is mixed with a small amount of powder binder is used as a plurality of magnetic body parts. A low-viscosity resin or an inorganic adhesive such as highly permeable glass is coated on the joint interface surface of a plurality of magnetic body parts, and the magnetic bodies are combined and pasted together to form a magnetic body.

[0005]

[Operation] By forming the magnetic material as described above, at the joining interface of the magnetic material (the joining interface of each magnetic material part),
Since the surface of the green compact is relatively porous compared to ferrite etc., when bonding with a low viscosity adhesive, excess adhesive permeates and is absorbed by the green compact, so no adhesive layer is formed and no magnetic gap is created. Furthermore, the adhesive that has penetrated into the porous parts of the powder compact engages with the pores and forms a hook, significantly increasing the adhesive strength, eliminating the need for core joining parts and resulting in a smaller, more reliable inductor. .

[0006]

EXAMPLES The present invention will be explained below by way of examples. First, referring to FIG. 1, the illustrated inductor includes air-core coils 2 having terminal electrodes 1, and these air-core coils 2 are installed inside a magnetic powder compact 3, which will be described later. An insulating layer 4 is provided between the terminal electrode 1 and the coil 2 and the magnetic compact 3. That is, the coil 2 is covered with the insulating layer 4. A coating 5 is applied to the entire surface of the inductor of such an inductor except for each terminal electrode 1.
is applied, making it a surface-mountable electronic component.

Referring to FIG. 2(a), when the above-mentioned combined bonding interface 11 of the magnetic powder compact 3 is microscopically observed, it is found that there is a bonding adhesive in the cavity 12 near the interface of the powder compact 3. The adhesive 10 is stuck and no adhesive layer is formed. Therefore, the strength is increased and the green compacts can be joined without forming a gap. In other words, in the above-mentioned inductor, there is no thick adhesive layer 10 that forms the magnetic gap 13 shown in FIG. 2(b), and as shown in FIG. Since the bonding adhesive 10 is embedded, strong bonding is achieved and no magnetic gap is formed.

Referring to FIG. 3, when forming the above-mentioned inductor, iron-based metal magnetic powder 6 is used as the magnetic powder, and 10% or less by weight of epoxy-based thermosetting resin 7 is powder bonded. A substantially E-shaped powder compact 3 and an I-shaped powder compact 3 are formed under pressure at a pressure of 5 TON/cm2. Then, an epoxy adhesive 10 with low viscosity and good permeability is applied to the joint joint portion (upper surface in FIG. 3) of the I-shaped powder compact 3. Next, the electrode terminal 1 is connected,
A substantially E-shaped powder compact 3 and an I-shaped powder compact 3 are arranged so that an air-core coil 2 formed of a self-bonding type copper wire with an insulation coating is installed inside the powder compact 3 via an insulating layer 4. The green compacts 3 are combined and joined. Thereafter, the entire outer surface of the green compact 3 is coated with powder coating except for the external terminal electrodes, and each terminal electrode 1 is bent so as to be compatible with surface mounting.

As shown in FIG. 4(a), the entire coil 2 to which the terminal electrode 1 is connected and each electrode 1 except for the part that will become the external electrode are coated in advance with an insulating resin 8 to form a powder compact 3. An insulating layer 4 is formed between the terminal electrode 1 and the coil 2. In addition, before assembling the powder compact 3, make sure that the terminal electrode 1 and the peeled part of the insulation coating of the coiled copper wire (the connection part with the terminal electrode) are electrically insulated from the powder compact 3 in FIG. 4(b). ), a part of the inside of the magnetic powder compact 3 may be coated with an insulating resin 8 in advance.

In the inductor thus obtained, a thick adhesive layer 10 forming a magnetic gap 13 as shown in FIG. 2(b) is not formed, and moreover, as shown in FIG. Since the bonding adhesive 10 is stuck in the hole 12 near the interface between the two, a strong bond is achieved.

[0011]

[Effects of the Invention] As explained above, in the present invention, a thick adhesive layer that becomes a magnetic gap is not formed, and moreover, the bonding adhesive is stuck in the voids near the interface of the powder compact. This makes the joint stronger and eliminates the need for core joint parts that were previously required. Furthermore, since electrical insulation is ensured between the magnetic material, the terminal electrode, and the coil, it is possible to use a powder compact with a low specific resistance or a low dielectric breakdown voltage. Furthermore, by applying a resin coating to the entire outer surface of the component except for the electrode portions, the moisture resistance can be improved. Since the outer surface of the component is insulated, surface mounting can be performed on the substrate pattern, and high-density component mounting can be performed. Thus, according to the present invention, a small and highly reliable inductor can be obtained. In the configuration of this embodiment, it is preferable to use an air-core coil as the coil 2 in order to obtain the effects of the present invention in order to achieve further miniaturization, but the effects of the present invention can also be obtained without any problem even if a coil wound with a bobbin or the like is used. Further, in this embodiment, iron-based metal magnetic powder was used as the magnetic powder, but the effects of the present invention can be obtained without problems even when ferrite magnetic powder or the like is used, regardless of the material of the magnetic powder. Further, the powder binder and the adhesive for joining the green compact in this example do not need to be epoxy resin, the coil electric wire does not need to be a self-fusing copper wire, and the green compact body divided shape of this example is an EI type, but other shapes such as an EE type can be used without any problems, and even when the number of divisions is increased, the effects of the present invention can be obtained without problems.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of an inductor according to the present invention.

FIG. 2 is an enlarged schematic diagram showing a green compact bonding interface in an inductor according to the present invention.

FIG. 3 is a diagram for explaining an example of manufacturing an inductor according to the present invention.

FIG. 4 is a diagram for explaining another example of manufacturing an inductor according to the present invention.

FIG. 5 is a diagram showing an example of a conventional inductor.

[Explanation of symbols]

1 Terminal electrode 2 Coil 3 Magnetic powder compact 4 Insulating layer 5 Inductor outer surface coating layer 6 Iron-based metal magnetic powder 7 Epoxy thermosetting resin 8 Insulating resin 10 Adhesive for joining powder compacts 11　Powder bonding interface 12 Pores within the compacted powder 13 Magnetic gap 14 Ferrite core 15 Metal plate for core holding 16 Coil bobbin with terminal 17 EE type ferrite core

Claims (4)

[Claims] 1. An inductor comprising a magnetic body formed by a plurality of magnetic body parts and a conductor disposed within the magnetic body, wherein each of the plurality of magnetic body parts includes a magnetic powder and a predetermined amount of a powder binder. The magnetic powder body to which is added is a pressure-molded magnetic powder body, and the magnetic body is formed by joining the plurality of magnetic body parts with a highly permeable adhesive. inductor. 2. The inductor according to claim 1, wherein the conductor is a coil formed of an insulated wire, and the coil is electrically connected to an electrode terminal drawn out of the magnetic body. Inductor. 3. In the inductor according to claim 2, the electrode terminal and the peeled part of the wire insulation coating, which is the connection part with the electrode terminal, are electrically insulated from the magnetic body. Characteristic inductor. 4. The inductor according to claim 3, wherein the outer surface of the magnetic material is entirely coated with resin.