KR101563092B1 - Inductance element - Google Patents

Abstract

The present invention provides an inductance element which is resistant to deformation of a material covering an outer surface of a core body of a magnetic core due to a temperature change and has stable magnetic characteristics.
An inductance element in which a coil is embedded in a magnetic core, the magnetic core comprising: a core body containing a magnetic powder and press-molded; and a cover resin layer covering the outer surface of the core body, At least a part of the conductive metal terminal is exposed on the outer surface of the core body without being covered with the coated resin layer so that the terminal conductive layer made of the conductive material and the binder resin is formed on the surface of the magnetic core, And the cover resin layer is formed of an epoxy-modified silicone resin.

Description

[0001] INDUCTANCE ELEMENT [0002]

The present invention relates to an inductance element in which a coil is embedded in a magnetic core.

In the inductance element in which the coil is embedded in the magnetic core, the metal plate terminal extending from the coil is exposed to the outer surface of the magnetic core, and the metal plate terminal is connected to the land portion of the external circuit formed on the wiring board, typically by soldering.

In the small inductance element, since the dimension of the coil is small, the metal plate terminals coming out of the magnetic core are also small, and the connection area for soldering with the external circuit can not be sufficiently secured, and the reliability of conduction can not be ensured , There arises a problem that the fixing strength of the chip component on the substrate is lowered.

In the chip component described in Patent Document 1 below, a coil is formed by winding a coating wire around a winding groove of a drum core, and the drum core and the coil are covered with an insulating resin material. The coil is electrically connected to the metal plate terminal, and the metal plate terminal is led out to the outside from the side face of the face resin made of the insulating resin material, and the front end is cut off from the side face end of the face resin. A conductive paste is applied to the entire side surface and the vicinity of the external resin, and the conductive paste is electrically coupled to the metal plate terminal.

That is, in the chip portion described in Patent Document 1, a conductive paste that is electrically conductive with the metal terminal is applied to the entire side surface of the external resin, and this conductive paste is used as a substantial connecting terminal portion to obtain a connection area required for soldering with an external circuit We are trying to secure it widely.

Japanese Patent Application Laid-Open No. 2-235305

Since the epoxy resin or the diallyl resin is used as the insulating resin material constituting the external resin, the chip component described in Patent Document 1 can be used for heating for other purposes or for the use environment of the chip component There is a problem that stress is applied to the drum core covered with the external resin due to the deformation of the insulating resin material due to heat to cause deformation, thereby causing a change in magnetic properties.

Therefore, it is conceivable to use an insulating resin material which is less deformed by heat as the external resin. In this case, however, the adhesiveness between the conductive paste and the external resin due to the difference from the binder of the conductive paste forming the connecting terminal portion The conductive paste tends to be peeled off, the reliability of conduction with the external circuit can not be ensured, and the fixing strength of the chip component on the wiring board may also deteriorate.

Therefore, the present invention provides an inductance element having stable magnetic characteristics by selecting the material of the coated resin layer so that no large stress acts on the core body from the coated resin layer in the inductance element having the coil embedded in the magnetic core . It is another object of the present invention to provide an inductance element that ensures adhesion between a terminal conductive layer formed on the surface of a core body and a core body.

In order to solve the above problems, an inductance element of a first aspect of the present invention is an inductance element in which a coil is embedded in a magnetic core, the magnetic core comprising: a core body containing a magnetic powder and press- Wherein at least a part of a metal terminal portion communicating with the coil is exposed without being covered with the cover resin layer on the outer surface of the core body and the surface of the magnetic core is covered with a conductive material and a binder resin The terminal conductive layer is formed, the terminal conductive layer is bonded to the covering resin layer and the terminal portion, and the covering resin layer is formed of an epoxy-modified silicone resin.

It is possible to obtain a stable magnetic property without giving a great stress to the magnetic core even when the temperature changes, and to provide a magnetic core having a terminal formed on the surface of the core body, The adhesion with the conductive layer can be ensured.

An inductance element according to a second aspect of the present invention is an inductance element in which a coil is embedded in a magnetic core, the magnetic core comprising: a core body containing a magnetic powder and containing a magnetic powder; Wherein at least a part of a metal terminal portion that is conductive to the coil is exposed without being covered with the covered resin layer on the outer surface of the core body so that a terminal conductive layer made of a conductive material and a binder resin is formed on the surface of the magnetic core, The terminal conductive layer is bonded to the covered resin layer and the terminal portion, and the covered resin layer is formed of the heat-resistant polyester resin.

The coated resin layer covering the outer surface of the core body of the magnetic core is made of heat resistant polyester resin so that stable magnetic properties can be obtained without giving a large stress to the magnetic core even when the temperature changes, The adhesion with the conductive layer can be ensured.

In the inductance element of the first aspect, the epoxy-modified silicone resin preferably contains a silicone epoxy varnish.

In the inductance element of the second aspect, the heat-resistant polyester resin preferably contains a phenol-modified alkyd resin or polyester silicone.

In the inductance element of the present invention, the binder resin of the terminal conductive layer is preferably an epoxy resin.

By using an epoxy resin, adhesion with the coated resin layer can be enhanced.

In the inductance element of the present invention, it is preferable that the terminal portion is a band-shaped body, and the surface of the band appears on the outer surface of the core body and is surface-bonded to the terminal conductive layer. It is possible to increase the junction area between the terminal and the terminal conductive layer by face bonding, thereby reducing the junction resistance.

According to the present invention, in the inductance element in which the coil is embedded in the magnetic core, the coated resin layer covering the outer surface of the core body of the magnetic core is made of the epoxy-modified silicone resin or the heat-resistant polyester resin, It is possible to provide an inductance element in which the coated resin layer does not give a large stress to the magnetic core and has stable magnetic properties. Further, according to the present invention, by forming the coated resin layer with the epoxy-modified silicone resin or the heat-resistant polyester resin, adhesion with the terminal conductive layer formed on the surface of the core body can be ensured.

1 is a perspective view showing a configuration of an inductance element according to an embodiment of the present invention.
Fig. 2 is a bottom view showing a configuration of the inductance element of Fig. 1. Fig.
Fig. 3 is a cross-sectional view taken along the line III-III in Fig. 1 showing the configuration of the inductance element of Fig.
4 is a partially enlarged cross-sectional view showing an enlarged portion of FIG.
Fig. 5 is a graph showing the relationship between the adhesive strength and the material of the coated resin layer in Examples and Comparative Examples. Fig.

Hereinafter, an inductance element according to an embodiment of the present invention will be described in detail with reference to the drawings.

Hereinafter, an example in which the coil and the terminal portion are integrated will be described, but the present invention can also be applied to a form in which the coil and the terminal portion are separated from each other.

1, in the inductance element 1 of the present embodiment, a coil 10 is embedded in a magnetic core 20. Fig. 1 shows a configuration of the inductance element 1, and is a perspective view in which the lower surface 22 of the magnetic core 20 faces upward. In Fig. 1, the coil 10 embedded in the magnetic core 20 is indicated by a solid line, and the outer surface of the magnetic core 20 is indicated by a dotted line.

As shown in Fig. 1, the coil 10 is formed by winding a belt-shaped conductive body 101 having a rectangular cross section in an elliptical shape around a center line O. Further, the shape of the coil 10 is not limited to an elliptical shape, and may be a true circular shape, and may be appropriately selected by those skilled in the art.

Both end portions 101a and 101a of the band body 101 forming the coil 10 are bent along a plane parallel to the center axis O and the tip portions of the both end portions 101a and 101a are bent, And a pair of terminal portions 15 and 18 are formed so as to extend along the lower surface 22 of the magnetic core 20. In this embodiment, the coil 10 and the pair of terminal portions 15 and 18 are integrally formed. The band body 101 that winds the coil 10 is formed of, for example, copper.

As shown in Fig. 4, a coil insulating layer 12 is formed on the surface of the band-shaped body 101. As shown in Fig. The coil insulation layer 12 has a two-layer structure in which, for example, a fused layer of nylon or the like is superimposed on the surface of an insulating resin layer. 4 shows that the coil insulating layer 12 is formed on the surface of the first terminal portion 15. The portion other than the band member 101 has the same sectional structure as that of the first terminal portion 15, A coil insulation layer 12 is formed.

As shown in Fig. 1, the magnetic core 20 is formed in a substantially cubic shape. 3, the magnetic core 20 includes a core body 21 as a powder compacting body formed by press-molding a magnetic powder and a binder resin, and a core body 21 covering the outer surface of the core body 21 to reinforce the core body 21 And a cover resin layer 22 formed on the substrate.

The first terminal portion 15 and the second terminal portion 18 are formed such that the band surfaces 15a and 18a of the first and second terminal portions 15 and 18 are located on the lower surface 21a of the core body 21 (The lower surface of the core body 20), and is substantially flush with the lower surface 21a of the core body 21. [ Both end portions 101a of the strip member 101 extending from the coil 10 to the first terminal portion 15 and the second terminal portion 18 are also substantially flush with the side surface 21b of the core body 21 .

3 and 4, each of the terminal portions 15 and 18 is disposed in a recess 22b having substantially the same shape as that of the terminal portion formed on the lower surface 21a of the core main body 21. As shown in Fig. The concave portion 22b is provided in the inside of the cavity in a state where the coil 10 and the terminal portions 15 and 18 are disposed in a cavity (not shown) in the compaction molding step, for example, Is formed when the magnetic core material (magnetic powder and binder resin) is pressed and heated under a constant pressing force.

As shown in Fig. 4, the coil insulating layer 12 is not formed on the end faces 15b, 18b of the terminal portions 15, 18, respectively. This is because the tip end faces 15b and 18b correspond to the cut faces when the coated lead wires are cut.

A gap 25 is formed between the distal end surfaces 15b and 18b of the terminal portions 15 and 18 and the stepped portion 21c of the core main body 21 as shown in Fig. The gap 25 is formed due to the spring back after the terminal portions 15 and 18 are pressed in the compaction molding step.

As shown in Figs. 3 and 4, all the outer surfaces of the core main body 21 are coated with a covered resin layer 22. Fig. As shown in Fig. 4, a part of the covered resin layer 22 is also filled in the gap 25. The first terminal portion 15 and the second terminal portion 18 are exposed on the lower surface 21a of the core body 21 so that the first terminal portion 15 and the second terminal portion 15, (18) and the cover resin layer (22) are face-bonded.

As shown in Fig. 2, on the lower surface of the magnetic core 20, a pair of terminal conductive layers 42 are formed with intervals in the lateral direction of the drawing. The terminal conductive layer 42 is formed in a strip shape on the outer surface of the covered resin layer 22 covering the lower surface of the magnetic core 20. [ 2, 3, and 4, a hole portion 43 is formed in a portion of the cover resin layer 22 that is partially overlapped with the terminal portions 15, 18, and the terminal portions 15, 18 are also removed from the portions corresponding to the hole portions 43. The coil insulating layer 12 covering the coil portions 18 is also removed. The terminal conductive layer 42 is electrically connected to the band surfaces 15a and 18a of the terminal portions 15 and 18 in the hole portion 43. [ Since the terminal portions 15 and 18 and the terminal conductive layer 42 are face-bonded, the junction resistance is reduced and the terminal portions 15 and 18 and the terminal conductive layer 42 are firmly bonded.

The terminal conductive layer 42 is formed in a strip shape over the entire length (the entire length in the vertical direction in the figure) of the side portions on the left and right sides of FIG. 2, The area of the terminal conductive layer 42 is sufficiently wider than the area of the terminal conductive layers 15 and 18. Most of the terminal conductive layer 42 is bonded to the surface of the cover resin layer 22 and only a part of the terminal conductive layer 42 is bonded to the band surfaces 15a and 18a of the terminal portions 15 and 18 in the hole portion 43 Respectively.

The terminal conductive layer 42 is composed of a conductive material and a binder resin. The binder resin of the terminal conductive layer 42 is, for example, an epoxy resin, and the conductive material is made of, for example, silver, specifically, silver paste or the like.

Although it is possible to secure the area required for soldering by forming the terminal portions 15 and 18 extending from the coil 10 to be elongated without forming the terminal conductive layer 42 made of silver paste or the like, The force acting on the magnetic core 20 from the terminal portions 15 and 18 becomes excessively large when the terminal portions 15 and 18 are bent on the outer surface of the magnetic core 20, The breakage of the crack or the like is likely to occur. When the magnetic core 20 is a powder compacted core formed of a magnetic powder and a binder resin, it is easy to be damaged if a large force is applied to the magnetic core 20, and a compact one having a size of each side of 1 to 2 mm The magnetic core 20 is easily broken.

It is necessary to form the concave portion 22b for disposing the terminal portions 15 and 18 on the outer surface of the magnetic core 20 as shown in Figs. 3 and 4. However, if the terminal portions 15 and 18 are long, It is necessary to secure a large area of the concave portion 22b. Since there is no magnetic powder in the concave portion 22b, if the concave portion 22b is widened, the volume occupied by the magnetic powder of the magnetic core 20 becomes small, and the inductance can not be increased.

In this embodiment, the terminal conductive layer 42 is formed of silver paste or the like, so that even if the length and the area of the terminal portions 15 and 18 extending from the coil 10 are small, . Since the terminal portions 15 and 18 can be made smaller, the force applied to the magnetic core 20 when forming the terminal portions 15 and 18 can be made small, and the magnetic core 20 is hardly damaged. In addition, since the concave portion 22b can be made smaller, the inductance of the magnetic core 20 can be prevented from lowering.

2, the terminal conductive layers 42 having a large area can be formed over the entire length of both side portions of the lower surface of the magnetic core 20, even if the terminal portions 15 and 18 are small in area , The reliability of conduction with the external circuit can be enhanced, and the fixing strength of the inductance element 1 on the wiring board can be increased. Therefore, it is optimum in the case of employing a compact spindle-forming core having dimensions of 1 to 2 mm on each side.

The core body 21 is a powder compacted core formed by pressing a magnetic powder and a binder resin in a cavity in a state where a coil 10 is provided in a cavity of a molding die. The magnetic powder is a magnetic alloy powder and is, for example, a Fe-based amorphous alloy powder mainly containing Fe and containing various metals such as Ni, Sn, Cr, P, C, B and Si, It is powdered by the method. The binder resin is an acrylic resin, a silicone resin, an epoxy resin, or the like.

The coated resin layer 22 is an electrically insulating resin layer formed of an epoxy-modified silicone resin or a heat-resistant polyester resin. As the epoxy-modified silicone resin, for example, a silicone epoxy varnish is used. As the heat resistant polyester resin, for example, phenol-modified alkyd resin or polyester silicone is used. The coated resin layer 22 preferably has a viscosity that can be impregnated on the outer surface of the magnetic core 20. [ It is possible to reinforce the mechanical strength of the surface of the core body 21 of the powder compact by the coated resin layer 22 after curing by impregnating the coated resin layer 22 from the outer surface of the core body 21 to a predetermined depth.

As the magnetic powder, an Fe-based amorphous alloy is preferably used. In this case, it is preferable to carry out the removal of the magnetostriction by performing annealing at a temperature of several hundreds of degrees Celsius after molding the core body 21. However, in the annealing step, the binder resin is thermally decomposed by heat, Is likely to become vulnerable. Therefore, a cover resin layer 22 is particularly required for the coarse milling core in which annealing is required.

If the coated resin layer 22 covering the outer surface of the core body 21 is made of epoxy-modified silicone or heat-resistant polyester resin, So that the magnetic characteristics of the core body 21 can be stabilized.

The cover resin layer 22 is formed of epoxy-modified silicone or heat-resistant polyester resin and the binder resin used in the terminal conductive layer 42 is made of an epoxy resin so that the cover resin layer 22 and the terminal conductive layer 42 can be increased.

Hereinafter, an embodiment will be described.

(Example 1)

Covered resin layer: Silicone Epoxy varnish (modified silicone resin) ES-1001N (manufactured by Shin-Etsu Chemical Co., Ltd.)

A solvent (xylene, butanol, diacetone alcohol) was added to dilute to a viscosity of 10 mPa · s.

Curing condition: After drying at 70 ° C for 30 minutes, it was cured by heating at 200 ° C for 45 minutes.

(Example 2)

Covered resin layer: Silicone Epoxy varnish (modified silicone resin) ES-1023 (manufactured by Shin-Etsu Chemical Co., Ltd.)

The solvent (xylene, diacetone alcohol) was added and diluted to a viscosity of 200 mPa · s.

Curing condition: After heating at 70 占 폚 for 30 minutes and drying, it was cured by heating at 200 占 폚 for 45 minutes.

(Example 3)

Covered resin layer: Silicone polyester varnish (polyester silicone) KR-5230 (manufactured by Shin-Etsu Chemical Co., Ltd.)

The solvent (propylene glycol monomethyl ether acetate: PGMAC) was added and diluted to a viscosity of 300 mPa · s.

Curing conditions: After heating at 70 ° C for 20-30 minutes and drying, it was cured by heating at 200 ° C for 45 minutes.

(Example 4)

Coated resin layer: Heat-resistant polyester resin (phenol-modified alkyd resin) H550 (manufactured by Meiden Chemical Co.)

The solvent (xylene) was added and diluted to a viscosity of 350 mPa · s.

Curing condition: After heating at 135 占 폚 for 60 minutes and drying, it was cured by heating at 180 占 폚 for 150 minutes.

(Example 5)

Covered resin layer: Silicone-modified epoxy varnish TSR194 (Momentive Performance Materials, Japan)

Solvents (xylene and ethylbenzene) were added and diluted to a viscosity of 180 mPa · s.

Curing condition: After heating at 70 ° C for 20-30 minutes and drying, it was cured by heating at 150 ° C for 30 minutes.

(Comparative Example 1)

Covered resin layer: methylphenyl-based silicone resin (straight silicone resin) KR-271 (manufactured by Shin-Etsu Chemical Co., Ltd.)

A solvent (xylene) was added and diluted to a viscosity of 180 mPa · s.

Curing conditions: After heating at 70 占 폚 for 30 minutes and drying, it was cured by heating at 250 占 폚 for 60 minutes.

(Comparative Example 2)

Covered resin layer: methyl-based silicone resin (straight silicone resin) KR-242A (manufactured by Shin-Etsu Chemical Co., Ltd.)

A solvent (toluene, isopropyl alcohol) was added to dilute to a viscosity of 12 mPa · s.

Curing condition: The solvent was heated at 70 占 폚 for 30 minutes and then cured by heating at 200 占 폚 for 35 minutes.

(Comparative Example 3)

Coated resin layer: two-component type epoxy adhesive AZ15 (subject): HZ15 (curing agent) = 100: 30 (manufactured by Nagase ChemteX Corporation)

Curing condition: The solvent was heated at 70 占 폚 for 20 to 30 minutes, and then cured by heating at 180 占 폚 for 60 minutes.

Adhesive strength and inductance change rate (L change rate) were measured for the above samples.

<Adhesive strength>

The sample to be used for the test was formed by brushing a covering resin layer corresponding to the covering resin layer 22 on the entire upper surface of a copper plate (thickness 0.1 mm x width 25 mm x length 100 mm) corresponding to the terminal portions 15 and 18 And two terminal conductive layers corresponding to the terminal conductive layer 42 were coated with a brush having a width of 25 mm and a length of 12.5 mm by means of a brush and two terminal conductive layers of the two samples To contact and cure each other.

Here, the terminal conductive layer was cured by heating at 175 DEG C for 1 hour using silver paste H9108 (binder: epoxy resin) (manufactured by Nemix Co., Ltd.).

The adhesive strength was determined by using a tensile tester (model No. 3365 (manufactured by Instron)) under condition No. 15 (tensile shear).

5 is a graph showing the relationship between the material of the coated resin layer and the adhesive strength in Examples and Comparative Examples. The adhesive strength referred to herein is the tensile strength (maximum load at the time of breaking of shear) (unit: MPa) measured by the above tensile tester. The measurement was carried out three times, and an average value (unit MPa) shown below was shown in Fig.

Example 1: 0.825

Example 2: 0.961

Example 3: 1.194

Example 4: 1.359

Comparative Example 1: 0.324

Comparative Example 2: 0.784

From these results, in Examples 1 to 4, the adhesive strength was 0.8 MPa, and sufficient adhesion between the coated resin layer and the terminal conductive layer was confirmed. On the other hand, in Comparative Examples 1 and 2, the adhesive strength was less than 0.8, and when straight silicone resin was used for the coated resin layer and an epoxy resin was used for the binder resin of the terminal conductive layer, Could know.

In the inspection by visual inspection, in Comparative Example 1, interface peeling occurred between the coated resin layer and the terminal conductive layer, and in Comparative Example 2, the coated resin layer was in a state of being easily peeled from the copper plate.

&Lt; Rate of change of inductance &

Preparation of sample: A core body embedded with a coil was produced by using a magnetic powder composed of an Fe-based amorphous alloy having a composition of Fe _71.4 Ni ₆ P _10.8 C _7.8 B ₂ Cr ₂ and a binder resin (acrylic resin). The dimensions were such that the width dimension corresponding to the longitudinal direction of the terminal conductive layer was 0.6 mm, the width dimension perpendicular to the width dimension was 2 mm, and the thickness dimension was 0.04 mm. The width dimension of the terminal conductive layer was 0.6 mm and the contact area between the terminal conductive layer and the terminal portion was 0.12 mm &lt; 2 &gt; or more.

The coil has a width of 0.28 mm and a thickness of 0.03 to 0.1 mm and a turn number of 3.5 to 14.5 turns, respectively.

Measurement method: A current of 0.5 mA was applied to a coil of an inductance element constituted by a coil and a core body, the initial inductance measured by an LCR meter was L0, and the inductance measured immediately after covering the core body with each covered resin layer was L1 , And the inductance element covered with the coated resin layer is left for 300 hours at 60 deg. C under an environment with a relative humidity of 95%, and the measured inductance is L2.

L1 / L0 x 100 (%) was the coat deterioration, and L2 / L1 x 100 (%) was the moisture deterioration.

(1) deterioration of coat

Example 1: -4%

Example 5: -3%

Comparative Example 3: -16%

(2) Humidity deterioration

Example 1: -2%

Example 5: -6%

Comparative Example 3: -8%

From the above results, in Examples 1 and 5, it was found that the change in inductance was sufficiently small in the coat deterioration test and the moisture-proof deterioration test, and magnetic properties could be ensured.

Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments, but can be modified or changed within the scope of the object of the improvement or the spirit of the present invention.

INDUSTRIAL APPLICABILITY As described above, the inductance element according to the present invention is useful in realizing an element having stable magnetic characteristics and high adhesion of the terminal conductive layer.

1: inductance element
10: Coil
12: Coil insulation layer
15, 18: terminals
15a, 18a: belt surface
20: Magnetic core
21: Core body
21a: when
22: Coated resin layer
42: terminal conductive layer
101: belt

Claims (6)

1. An inductance element in which a coil is embedded in a magnetic core,
Wherein the magnetic core comprises a core body containing magnetic powder and pressure-molded, and a cover resin layer covering the outer surface of the core body, wherein at least a part of a metal terminal portion conducting to the coil is formed on the outer surface of the core body Exposed without being covered with the coated resin layer,
A terminal conductive layer made of a conductive material and a binder resin is formed on the surface of the magnetic core, the terminal conductive layer is bonded to the covered resin layer and the terminal portion,
Wherein the coated resin layer is formed of an epoxy-modified silicone resin. 1. An inductance element in which a coil is embedded in a magnetic core,
Wherein the magnetic core comprises a core body containing magnetic powder and pressure-molded, and a cover resin layer covering the outer surface of the core body, wherein at least a part of a metal terminal portion conducting to the coil is formed on the outer surface of the core body Exposed without being covered with the coated resin layer,
A terminal conductive layer made of a conductive material and a binder resin is formed on the surface of the magnetic core, the terminal conductive layer is bonded to the covered resin layer and the terminal portion,
Wherein the coated resin layer is formed of a heat-resistant polyester resin. The method according to claim 1,
Wherein the epoxy-modified silicone resin contains a silicone epoxy varnish. 3. The method of claim 2,
Wherein the heat-resistant polyester resin comprises a phenol-modified alkyd resin or polyester silicone. 5. The method according to any one of claims 1 to 4,
Wherein the binder resin of the terminal conductive layer is an epoxy resin. 3. The method according to claim 1 or 2,
Wherein the terminal portion is a band body and the surface of the band appears on an outer surface of the core body and is surface bonded to the terminal conductive layer.

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