JP3108931B2 - Inductor and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductor used for an electronic circuit or the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art As shown in FIG. 11, a conventional inductor has a wound bobbin 42 made of a magnetic material or a material other than a magnetic material. The winding bobbin 42 is provided with a winding coil 45 around which an electric wire with insulation coating is wound. At both ends of the wire of the wound coil 45, electrode terminals 4
3 and 44 are connected. A magnetic core is put into the winding bobbin 42, and thereafter, the resin 41 containing magnetic powder is filled, and the coil 45 is covered with the resin 41 containing magnetic powder, so that no leakage magnetic flux is output to the outside.

[0003]

However, in the inductor, when the same material or different kinds of magnetic materials are joined in the magnetic path of the generated magnetic flux Φ4, the interface G4 at the joining portion forms a magnetic gap. Due to this magnetic gap, the inductor has a problem that the induction coefficient is low and the reliability is reduced.

In order to increase the degree of filling of the magnetic powder in order to increase the induction coefficient, when mixing the magnetic powder and the resin, the ratio of the resin is reduced and a large amount is formed by a method such as pressure molding. The coil 45 must be covered with magnetic powder. At that time, it is necessary to increase the pressure of the pressure molding. However, while the molding pressure was increased, the coil 45
Since the coil 45 is filled in the magnetic powder, which is easier to compress than in the case of the above, the pressure borne by the coil 45 during pressurization increases. Therefore, the molding pressure of the magnetic powder itself is not effectively increased, and there is a problem that the coil 45 itself is crushed.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a highly reliable inductor having a small size and a large inductance and impedance, and a method of manufacturing the inductor.

[0006]

According to the present invention, there is provided an inductor comprising a magnetic material, a coil attached to the magnetic material, and a terminal portion drawn out of the coil to the outside of the magnetic material. Is thermosetting to bind magnetic powder
A first green compact formed by press-forming a binder-containing magnetic powder containing a binder, which is a resin, and a second green compact;
2 is a binder similar to the binder-containing magnetic powder.
Magnetic powder containing, or the same as the above magnetic powder containing a binder
Pre-pressed magnetic powder containing a binder
The terminal portion is sandwiched the magnetic body, wherein the coil is in the magnetic cage sealed write Marete the body, said magnetic body connecting portion between said first green compact and said second green compact An inductor is obtained in which the thermosetting binder is integrated with the thermosetting binder in a state where the main pressing is performed until the interface is removed. Also,
According to the present invention, the coil is an air-core coil, has the terminal portions electrically connected to both ends of the air-core coil, and the binder is a thermosetting resin that binds the magnetic powder. In addition, an inductor is obtained in which the first green compact and the second green compact sandwich the terminal portion and the coil and are integrated with each other. Further, according to the present invention, the magnetic powder
Forming a first green compact by press-molding a binder-containing magnetic powder containing a binder which is a thermosetting resin with a molding die, and installing a coil having a terminal portion in the molding die Installing a second green compact in a molding die on the opposite side to the first green compact with respect to the coil ;
When the green compact is the same as the binder-containing magnetic powder,
Powder or the same binding as the binder-containing magnetic powder
And press-molding a magnetic powder containing an agent. The first green compact is abutted against the second green compact, and the first green compact and the second green compact are interposed between the first green compact and the second green compact. be integrated by applying pressure the molding to the interface at the connecting portion is removed, to release the molded product from the mold, after which the binding agent of the inductor, characterized in that the thermosetting treatment A manufacturing method is obtained.

[0007]

The inductor constructed and manufactured by the above-described means has no magnetic gap and has a high induction coefficient because there is no interface due to the joining of the magnetic materials in the magnetic path of the magnetic flux generated when a current flows through the coil. Also, since the magnetic powder is compacted in advance and fitted with the coil, the packing density of the magnetic powder is high and the induction coefficient is high, so that the same number of turns can be reduced to obtain the same inductance or impedance, and the DC resistance can be reduced. Further, an inductor having high reliability can be obtained from the viewpoint of preventing a decrease in reliability due to the presence of the interface of the magnetic material, which has conventionally occurred, and from the viewpoint of reducing the collapse of the internal coil.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an inductor according to the present invention and a method of manufacturing the same. FIG. 1 is a configuration diagram showing one embodiment of the inductor of the present invention. 2 to 5 are schematic views showing the steps of manufacturing the inductor of FIG.

The inductor has magnetic members 6 and 11, a coil 5 attached to the magnetic members 6 and 11, and terminal portions 3 and 4 drawn out of the coil 5 to outside the magnetic members 6 and 11. . The magnetic bodies 6 and 11 are composed of a first green compact 6 obtained by press-forming a magnetic powder containing a binder and a second green compact 1.
1 is included. The second green compact 11 is formed by combining the first green compact 6.
Magnetic powder with binder similar to magnetic powder with mixture, or
Is the same binder as the binder-containing magnetic powder of the first green compact 6
The magnetic powder containing powder is preformed under pressure. Terminal 3
And 4, the coil 5 is sandwiched between the magnetic bodies 6 and 11. Coil 5 is enclosed in magnetic bodies 6 and 11
At the same time , the magnetic bodies 6 and 11 are subjected to pressure main molding to be integrated. The terminal portions 3 and 4 are lead terminals from which both ends of the coil 5 are drawn out or terminal electrodes connected to both ends of the coil 5. The inductor obtains a desired inductance or impedance at these terminals 3 and 4.

The coil 5 uses an air-core coil. The terminals 3 and 4 are electrically connected to both ends of the coil 5, respectively. Binder binds magnetic powder
A thermosetting resin (powder bonding resin), the first green compact 1 and the second green compact 11 sandwich the terminal portions 3, 4 and the coil 5 in the magnetic body 6 and 11. The terminal portions 3 and 4 and the coil 5 are integrated with the magnetic bodies 6 and 11.

Next, a method of manufacturing the inductor will be described with reference to FIGS. First, a magnetic powder 1 such as ferrite mixed with a binder made of a thermosetting resin such as an epoxy resin is formed into a cap shape only by pressing in the vertical direction using upper and lower pressing dies 8 and 9 to form a first powder. A green compact 6 is made. At this time, the magnetic powder 1 is molded without curing the resin. The first green compact 6 is a coil 5
Is formed in the shape of a Roman letter E so that it just enters. Thereafter, as shown in FIGS. 3 and 4, while the first green compact 6 is left in the molding die 7, the second green compact 11 equivalent to the magnetic powder 1 is inserted into the lower molding die 10, A coil 5 electrically connecting the terminal electrodes 3 and 4 is provided between the upper and lower molds 7 and 10. Next, as shown in FIG. 5, the upper and lower molding dies 7 and 10 are overlapped with each other, and the upper and lower pressing dies 12 and 13 are pressed in the vertical direction to carry out integral press main molding to produce a molded body. At this time, the terminals 3 and 4 are sandwiched between the upper and lower molding dies 7 and 10, and the coil 5 is sealed in the first and second green compacts 6 and 11. Then, the upper and lower molds 7 and 10
Is released and post-heated to cure the resin for powder bonding. According to this manufacturing method, there is no interface at the joint between the magnetic bodies 6 and 11 composed of the first green compact 6 and the second green compact 11,
An inductor having a high magnetic powder density on the side surface of the coil 5 and the core of the coil 5 can be obtained.

FIGS. 6 to 9 show a second embodiment of the method of manufacturing an inductor according to the present invention.

First, as shown in FIG. 6, a magnetic powder 21 such as ferrite mixed with a binder made of a thermosetting resin such as an epoxy resin is pressed into a molding die 2 for vertical pressing without curing the resin.
According to 8 and 29, the first green compact 26 is formed by molding into a cap shape only by pressing in the vertical direction. First green compact 26
Is formed in the shape of a letter E having a Roman cross section so that the coil 25 can be inserted exactly. The first green compact 26 is left in the molding die 27.
Also, as shown in FIG.
The first green compact 2 is inserted by inserting a magnetic powder 31 equivalent to
6 and press-molded with the upper and lower pressing molds 35 and 36 without curing the bonding resin in the same manner as described above, As shown in FIGS. 8 and 9, the molding dies 27 and 30 are overlapped, and the coil 25 having the terminal electrodes 23 and 24 electrically connected therebetween is installed as shown in FIGS. next,
As shown in FIG. 10, the pressurization in the vertical direction is performed by the vertical pressing dies 32 and 33 to perform the integral press main forming. Thereafter, the inductor is obtained by releasing the upper and lower molds 27 and 30 and then heating and curing the resin for powder bonding. According to this manufacturing method, there is no interface at the joint between the magnetic bodies 6 and 11 of FIG. 1 constituted by the first green compact 26 and the second green compact 34, An inductor having a high magnetic powder density can be obtained.

[0014]

The inductor thus obtained is:
Since there is no magnetic gap G4 shown in FIG. 11 and the like, the induction coefficient is high, the reliability instability due to the conventional state such as polishing of the magnetic joint is eliminated, and an inductor with improved reliability is obtained.

In addition, the periphery of the coil is covered with a high-density magnetic powder compact in advance, and after that, since the coil is integrally formed, concentration of the pressure on the coil can be reduced. A highly reliable inductor with reduced coil collapse can be obtained.

The binder used in the present embodiment is not limited to an epoxy resin, and a phenol resin-based resin, a silicone resin-based resin, or any other resin can be used as long as it is a thermosetting resin. . The magnetic powder is not limited to ferrite powder, and the effect of the present invention can be obtained even if it is a metal-based magnetic powder if insulation between the powders is ensured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the inductor of the present invention.

FIG. 2 is a schematic view showing one forming step in a first embodiment of the manufacturing steps of the inductor of FIG. 1;

FIG. 3 is a schematic diagram showing one step of a molding step following the step of manufacturing the inductor of FIG. 2;

FIG. 4 is a perspective view showing an arrangement of a coil and a green compact of FIG. 3;

FIG. 5 is a schematic view showing one step of a molding step following the step of manufacturing the inductor of FIG. 2;

FIG. 6 is a schematic view showing a first example of a manufacturing process of the inductor of FIG. 1 and showing one step of a molding step.

FIG. 7 is a schematic view showing one step of a molding step following the step of manufacturing the inductor of FIG. 6;

FIG. 8 is a schematic view showing one step of a molding step following the step of manufacturing the inductor of FIG. 7;

FIG. 9 is a perspective view showing the arrangement of the coil and the green compact of FIG. 8;

FIG. 10 is a schematic view showing one step of a molding step following the step of manufacturing the inductor of FIG. 8;

FIG. 11 is a cross-sectional view of a conventional inductor and an enlarged cross-sectional view in which a joint portion of the inductor is enlarged.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic powder 3 Terminal part 5 Coil 6 1st compact 7 Molding mold 8 Mold 11 Second compact 21 Magnetic powder 26 1st compact 31 Magnetic powder 34 2nd compact 41 Combination Agent-containing magnetic powder 42 wound bobbin 44 terminal 45 coil

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01F 17/04 H01F 27/24 H01F 27/2255 H01F 38/42 H01F 41/00 H01F 41/02

Claims (3)

(57) [Claims] 1. An inductor including a magnetic body, a coil attached to the magnetic body, and a terminal portion drawn out of the coil to the outside of the magnetic body, wherein the magnetic body is made of a magnetic powder.
A first green compact having a binding agent mixed magnetic powder containing a binder is a thermosetting resin for engagement by pressure preformed second
And a green compact, wherein the second compact is a magnetic material containing the binder.
Magnetic powder containing a binder similar to the conductive powder, or the above-mentioned binding
Pressurized magnetic powder with binder similar to magnetic powder with binder
The terminal is sandwiched between the magnetic members.
Marete cage, the coil is sealed in the magnetic body write Marete
Cage, the magnetic body is the binding that is the thermosetting state until pressure圧本molding surface is removed is applied in the connection portion between the first green compact and said second green compact
An inductor characterized by being integrated by an agent . 2. The coil is an air-core coil, has the terminals electrically connected to both ends of the air-core coil, and the binder is a thermosetting resin for bonding the magnetic powder. said first green compact and said second green compact is sandwiched the terminal portion and the coil, <br/> of claim 1, wherein that they are integrated Nacta. 3. A thermosetting resin for binding a magnetic powder.
Forming a first compact by press-molding a binder-containing magnetic powder containing a binder with a molding die to form a first compact; installing a coil having a terminal portion in the molding die; Into the molding die on the side opposite to the first green compact .
Placing the second green compact, wherein the second green compact is
Magnetic powder containing a binder similar to the magnetic powder containing the agent, or
The same binder-containing magnetic powder as the binder-containing magnetic powder is used.
Is obtained by pressure preformed said first abutment to the green compact the second green compact, the interface in the first green compact and the connection portion between the second green compact Add until removed
Be integrated is subjected to pressure the molding, the molded body to release from the mold, the inductor manufacturing method, which comprises heat-curing the binder subsequently.