KR100655418B1 - Coil integrated inductor - Google Patents

Abstract

A coil integrated inductor is provided to enhance coupling force between a magnetic body and an electrode by a coupling hole and a groove unit formed in inner electrodes. In a coil integrated inductor, a coil(110) is wound with the predetermined number. Electrodes(120,130) are coupled with the end portions of the coil(110). A magnetic body(140) is integrated with the coil(110) and the inner electrodes of the electrodes(120,130). The magnetic body(140) is formed through an additional metallic mold by compound magnetic material including magnetic powder, binder, and epoxy silane and additional material including insulation filler and lubricant.

Description

[0001] COIL INTEGRATED INDUCTOR [0002]

1 is an exemplary view showing a conventional integrated type inductor,

FIG. 2 is a perspective view of a winding integrated-type inductor according to the present invention,

FIGS. 3 and 4 are views showing the configuration of a coil and an electrode according to the present invention,

5 is a partially enlarged view showing the configuration of a coil and an electrode according to the present invention,

6 is an illustration showing a coil, an electrode, and a magnetic body according to the present invention,

FIG. 7 is an illustration showing a seating part formed on the upper surface of the body according to the present invention, FIG.

8 is an exemplary view showing the lower surface of the body according to the present invention,

9 is an exemplary view showing a cut-off state of an external electrode according to the present invention,

10 is an exemplary view showing a bent state of the external electrode according to the present invention,

11 is a partially enlarged view showing a part of a magnetic body according to the present invention,

FIG. 12 is a flowchart illustrating a manufacturing process of an integral inductor according to the present invention.

Description of the Related Art

100: Winding integrated type inductor 110: Coil

111, 112: end portions of the coil 120, 130: electrode

120a, 130a: internal electrode 120b, 130b: external electrode

121a, 121b, 131a, 131b: engagement holes 122, 132:

140: Magnetic body 140a: Lower magnetic body

141, 142:

[0001] The present invention relates to an inductor, and more particularly, to a coil integrated inductor in which surface resistance is high and mechanical strength is remarkably improved and surface mounting is facilitated.

Conventional inductors in the art include a coil wound inside, an electrode bonded to both ends of the coil, and a composite magnetic body (hereinafter referred to as a "magnetic body") integrated with the coil. As a material of the magnetic material, a metallic magnetic material such as Sendust, Iron, Permalloy, etc. in a powder state and a non-cured organic or inorganic binder are mainly used. The organic binder not only enhances the mechanical strength of the core itself, but also increases the resistance of the core while being present between the metallic magnetic bodies.

The powdered state dust, iron, and permall have a high saturation magnetic flux density value, so that they do not easily saturate even at high currents and provide excellent current superimposition characteristics. Such a powder is molded together with a coil having an electrode, and an inductor in which a winding is finally embedded, so-called a coil integrated inductor, is fabricated.

In the case of an inductor in which a magnetic material is embedded around a coil, since the magnetic effective sectional area can be maximized, a high inductance (L) can be obtained even with a small number of turns. In particular, the smaller number of windings means that the length of the coils is shortened, which means that the DC resistance (DCR) of the coils can be reduced, thereby reducing the heat generation and consequently increasing the efficiency of the inductors. Since the above-described inductor integrated with a winding is widely used in a power circuit of an electronic device in which thinning and shortening are essential, and an external electrode of the inductor is formed so as to be surface-mountable mainly on a power supply circuit, an SMD (Surface Mounded Device) Type inductors.

However, since such a winding integrated inductor is in direct contact with the embedded electrode (internal electrode) and the magnetic body, insulation between the electrode and the core is inevitably insufficient. Conventional winding integrated inductors have a relatively low insulation resistance value (or surface resistance value) between the electrode and the magnetic body of about several kOK to several M ?.

In addition, the organic binder used in the conventional winding integrated inductor has a limitation in increasing the mechanical strength of the inductor. Moreover, since the electrode of the inductor is structurally bonded to one surface of the body and coupled with the magnetic body, as shown in A in FIG. 1, the mechanical strength of the inductor is very low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is a primary object of the present invention to provide an integral inductor with a winding having a high surface resistance and improved mechanical strength.

The features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. Prior to this, terms and words used in the present specification and claims are to be interpreted in accordance with the technical idea of the present invention based on the principle that the inventor can properly define the concept of the term in order to explain his invention in the best way. It should be interpreted in terms of meaning and concept. It is to be noted that the detailed description of known functions and constructions related to the present invention is omitted when it is determined that the gist of the present invention may be unnecessarily blurred.

FIG. 2 is a perspective view showing a winding integrated type inductor according to the present invention. FIG. Referring to the drawing, a coil integrated inductor 100 (hereinafter referred to as 'an inductor') includes a coil 110 wound with a predetermined number of turns, electrodes 120 and 130 made of conductive material connected to an end of the coil, And a magnetic body 140 integrated with a part of the electrode.

3, the first end 111 and the second end 112 of the coil 110 are welded or brazed to the first electrode 120 and the second electrode 130, respectively. The coil 110 is coated with a resin insulating film and it is preferable to set the insulating film to a polyamide system when the expected exothermic temperature in the circuit is equal to or higher than 125 ° C. However, It is not.

Each of the electrodes 120 and 130 is provided with a pair of coupling holes 121a and 121b (131a and 131b) as shown in Fig. These coupling holes function to increase the coupling force between the electrode and the magnetic body. The ends of the electrodes 120 and 130 facing the coil 110 form a curved portion corresponding to the curvature of the coil 110 and additionally have a recessed portion for increasing the coupling force between the electrode and the magnetic body 140 122, and 132 are formed at a predetermined depth in the center of the curved portion. The depths of the recessed grooves 122 and 132 have a depth adjacent to the folding line BL shown in FIG. Herein, the folding line BL refers to an imaginary line in which the electrode is bent, and the magnetic body 140 is located inside the folding line BL. In the present embodiment, the diameter of the coupling hole is set to 0.3 to 1 mm, but the diameter may be set differently depending on the size of the inductor and the size of the electrode, and thus the present invention is not limited thereto.

The electrode portions integrated with the magnetic body 110 are divided into the internal electrodes 120a and 130a and the remaining electrode portions are divided into the external electrodes 120b and 130b on the basis of the curved line BL .

FIG. 6 shows a magnetic body 140 formed with a coil 110 inside a folding line BL. The magnetic body 140 according to a characteristic aspect of the present invention is a supplementary material including a magnetic powder, a binder, and a mixed magnetic material including an epoxy silane, and an insulating filler and a lubricant. A separate mold (not shown) Lt; / RTI >

Any of iron powder, permoloy powder, sentust powder, amorphous alloy powder, and ferrite powder may be used as the component. However, the magnetic powder should have a particle shape close to a sphere and have an average particle size of 30 mu m or less. This is because when the particle size is large or the non-spherical shape is sharp, the possibility of damaging the insulating coating of the coil 110 during the molding process of the magnetic body 140 is high.

Since the above-mentioned magnetic powder contains a metallic powder, it must be insulated by an appropriate method, unlike a ceramic magnetic body having a high resistance by itself. If the magnetic powder is not insulated above a certain level, the eddy current loss between the particles increases, resulting in high heat generation. Therefore, the surface of the metallic powder may be subjected to acid treatment through a phosphoric acid treatment as an insulating method of the magnetic powder, or a binder may be used. The inorganic binder is exemplified by water glass, and in the case of an organic binder, a polyimide resin or an epoxy resin is suitable.

The binder is made into a liquid phase through an organic solvent such as alcohol, metaethyl ketone or the like in order to increase the mixing property with the magnetic powder. The content of the binder is preferably 1 to 6% by weight relative to the magnetic powder. As the content of the binder increases, the insulation between the magnetic powders can be increased, but the permeability decreases and the saturation flux density decreases.

Epoxysilane (chemical formula: C ₉ H ₂ O ₅ Si) basically functions to increase the bonding strength between an organic material and an inorganic material. The epoxy silane is added in an amount of 0.5 to 3% by weight based on the magnetic powder in the range of 1 to 6% by weight of the magnetic powder, based on the characteristic feature of the present invention. This increases the surface resistance and mechanical strength of the magnetic body 140. It can be seen that the surface resistance and the strength of the inductor are changed according to the content of the binder and the epoxy silane (parts by weight relative to the magnetic powder) as in the experimental example shown in the following [Table 1].

Measuring conditions Surface resistance burglar (One) Binder 4% 60 ㏁ 450N (2) Binder 4% + epoxy silane 0.5% 450 ㏁ 600N (3) Binder 3.5% + epoxy silane 1% 500 ㏁ 550N (4) Binder 3% + epoxy silane 1.5% 400 ㏁ 360N

The surface resistance was measured by measuring the resistance value between the external electrode and the upper surface of the magnetic body after manufacturing the inductor having the size of 10 mm x 10 mm x 3 mm and the mechanical strength was measured in a bar of 20 mm x 10 mm x 5 mm Bar type specimens were manufactured and the bending strength values were measured. From the results of (1) and (2) above, it can be seen that the surface resistance was significantly increased when the epoxy silane was added from 450 to 600 M in mechanical strength value from 60 M to 450 M.

The above-mentioned mixed magnetic material (magnetic powder, binder, epoxy silane) should be produced in the form of granules. First, a liquid organic binder is thoroughly mixed with a magnetic powder together with an epoxy silane, and the organic solvent is volatilized through an oven heated at 100 캜. The binder, the epoxy silane and the magnetic powder are then in a cake state. The cake is passed through a 200 mesh (mesh) sieve to form granules.

Spray drying can also be used as another method for making the granular shape. This method is a method of making a liquid binder, an epoxy silane and a magnetic powder into a slurry in a state of 1000 cps, and then spraying it into a drier heated to 70 to 100 ° C to form a spherical granule of about 100 μm.

In order to form the magnetic body 140, the above-described additional material (insulating filler, lubricant) is mixed together before the granular mixed magnetic material is filled in the mold.

The insulating filler functions to further improve the insulation of the mixed magnetic material, and talc, kaolin, MgO, CaO, or a mixture thereof can be used. The insulating filler preferably has a weight part of 0.5 to 5% by weight of the magnetic powder. Of course, the present invention is not limited to the weight of the above-mentioned insulating filler. However, when the content of the insulating filler is 0.5% or less, sufficient insulation of the magnetic powder can not be expected. On the other hand, do.

The lubricant functions to improve the fluidity of the mixed magnetic material and the insulating filler in the mold. As the lubricant, one or any combination of one or more of zinc stearate, calcium stearate and waxes may be added. The addition amount is preferably 0.1 to 0.7% by weight relative to the magnetic powder.

The external electrodes 120b and 130b are folded on the folding line BL on the upper surface of the magnetic body 140 formed with the mixed magnetic material and the additive material through the metal molds, 142 (see Fig. 7). The seat portion is formed by a mold (not shown) provided in the mold.

9 shows a state in which the external electrodes 120b and 130b are cut and FIG. 10 shows a state in which the cut external electrodes 120b and 130b are bent And is seated in the seat portion.

The current superimposition characteristic of the inductor 100 according to the present invention may be changed according to the inner diameter of the coil 110. [ Basically, when the inner diameter of the coil is set so as to be equal to the inner cross-sectional area of the coil of the formed inductor and the outer cross-sectional area of the coil, the best current overlap characteristic is obtained. In the present invention, it is preferable that the inner cross-sectional area of the coil is in the range of 70 to 130% of the outer cross-sectional area. If the inner cross-sectional area of the coil is larger than the outer cross-sectional area, the inductance value at the same winding increases, but the outer coil is magnetically saturated before the inside of the coil. In the opposite case, the effective magnetic cross-sectional area inside the coil is reduced to reduce the inductance value, and the inside of the coil is magnetically saturated before the outside, thereby reducing the efficiency.

11, the height of the lower magnetic body 140a located at the lower end of the magnetic body 140, that is, below the inner electrodes 120a and 130a and the coil 110, Sectional area of the coil 110 is about 60% of the internal cross-sectional area of the coil 110. [ When the height of the lower magnetic body 140a is set to a height of 60% or less, the magnetic saturation of the lower magnetic body 140a first proceeds to decrease the current overlapping property and increase the heat generation. When the height of the lower magnetic body 140a is too large, The cross-sectional area becomes unnecessarily large, and the size of the inductor is increased. This results in contradiction to the miniaturization.

Hereinafter, a manufacturing method of the integral type inductor 100 according to the present invention will be described with reference to FIG. First, the end portions 111 and 112 of the coil 110 wound by a predetermined number of times are bonded to the electrodes 120 and 130 (S10).

The magnetic material, the binder and the epoxy silane are mixed to prepare a mixed magnetic material in granular form (S20). At this time, the binder and the epoxy silane are mixed with 1 to 6% by weight and 0.5 to 3% by weight of the magnetic material, respectively.

Next, the coils 110 bonded to the electrodes 120 and 130 are placed in a mold (not shown), and the mixed magnetic material and the additional material are mixed and filled in the mold (S30). Here, the insulating filler and the lubricant constituting the additional material each have a weight portion of 0.5 to 5% and a weight portion of 0.1 to 0.7% of the magnetic powder.

After the operation S30, the magnetic body 140 is formed by compressing the mixed magnetic material and the additional material using a uniaxial press (not shown) with a force of 3 to 10 tons per cubic centimeter (cm3) (S40). At this time, after the compression molding, the density of the magnetic body 140 is preferably 5.0 to 7.2 g / cm 3.

After the above-described steps S10 to S40 are performed, the inductor 100 taken out of the mold is heat-treated at a high temperature for 1 to 3 hours at which the binder is cured (S50). When the added binder is an organic binder, it is preferably heat-treated at a temperature of 120 to 400 ° C, and in the case of an inorganic binder, it is preferably a temperature range of 400 to 700 ° C.

Finally, the external electrodes 120b and 130b are cut to a length that can be seated on the seating portions 141 and 142 formed on the upper surface of the magnetic body 140, and then bent (S60 and S70).

According to the present invention as described above, the following effects are provided.

First, there is an effect that the coupling force between the magnetic body 140 and the electrode can be enhanced through the coupling holes and the recesses in which the internal electrodes 120a and 130a are formed. This improves the reliability of the inductor because it can reduce the breakage of the lower magnetic body, which has occurred when the external electrode is bent.

Second, by using a mixed magnetic material including epoxy silane when forming the magnetic body 140, surface resistance and mechanical strength can be remarkably increased compared with the conventional art.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It will be appreciated by those skilled in the art that numerous changes and modifications may be made without departing from the invention. Accordingly, all such appropriate modifications and changes, and equivalents thereof, should be regarded as within the scope of the present invention.

Claims (7)

(120, 130) joined to the ends (111, 112) of the coil and a magnetic body (120, 130) integrated with the coils and the internal electrodes (120a, 130a) A surface mountable inductor comprising: Wherein the magnetic body (140) is formed from a mixed magnetic material including a magnetic powder, a binder and an epoxy silane, and an additional material including an insulating filler and a lubricant, through a separate mold. The method according to claim 1, The internal electrodes (120a, 130a) Wherein a curved portion is formed at a front end facing the coil (110), and recessed portions (122, 132) are formed in the center of the curved portion. 3. The method according to claim 1 or 2, The internal electrodes (120a, 130a) , And a pair of coupling holes (121a, 121b) (131a, 131b) are formed, respectively. The method according to claim 1, The magnetic powder may contain, Iron powder, permalloy powder, sendust powder, amorphous alloy powder, and ferrite powder. delete The method according to claim 1, The binder and the epoxy silane, Wherein the magnetic powder is 1 to 6% by weight and 0.5 to 3% by weight of the magnetic powder, respectively. The method according to claim 1, The insulating filler material and the lubricant may include, Is 0.5 to 5% by weight and 0.1 to 0.7% by weight based on the magnetic powder, respectively.

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