KR101046879B1 - Ultra Thin Power Inductors - Google Patents

Abstract

The present invention relates to an ultra-thin power inductor, wherein a pattern circuit fabricated using a conductive material is formed on a sheet filled with a soft magnetic metal alloy powder having an optimized powder location along a magnetic path.

In addition, by installing a magnetic sheet on top of the ultra-thin power inductor, to provide a closed-type ultra-thin power inductor that can minimize the leakage flux.

Through the inductor, a sheet filled with metal soft magnetic powder having high magnetization density has a minute gap between powders whose shape is optimized along the magnetic path, thereby ensuring high DC overlapping characteristics and stable inductance up to a high frequency region. have.

In addition, it is possible to provide a large area power inductor while maintaining a thin thickness.

Power inductors, ultra thin, magnetic sheets.

Description

ULTRA THIN TYPE POWER INDUCTOR

The present invention relates to an ultra-thin power inductor, and more particularly, to an ultra-thin power inductor having improved mechanical characteristics and saturation magnetization characteristics using a circuit using a magnetic sheet and a conductive material.

With the miniaturization of electronic devices, the miniaturization and weight reduction of the electronic components used for them are progressing.

For example, various devices including the CPU used in various electronic circuits are aimed at high speed and high frequency, and many attempts have been made to reduce their size, but passive devices such as inductors and transformers, which are essential circuit elements of electronic circuits, have been made. The reality is that miniaturization is difficult.

In general, in the case of miniaturization of passive elements such as inductors and transformers, when the volume of the magnetic body is reduced, the magnetic body causes magnetic saturation and a problem that the amount of current that can be handled as a whole decreases.

Therefore, in order to improve such a problem, there have been attempts to form inductors and transformers in a stacked type.

However, oxide ferrite, which is mainly used as a magnetic material of a conventional multilayer power inductor, has high magnetic permeability and electrical resistance, but has a low saturation magnetic flux density, resulting in a large decrease in inductance due to magnetic saturation and poor DC superposition characteristics.

1 illustrates such a conventional wound ferrite-based power inductor 50.

An inductor using such a ferrite has to go through a sintering process after installing the circuit 53 on the ferrite plate 52. A change in volume occurs due to the distortion of the high temperature sintering process.

In order to correct the change in volume due to this warpage phenomenon, in order to manufacture the accurate inductor magnetic core 51, an additional machining process that requires additional machining of the magnetic core 51 due to the volume change is required, There is a limitation in securing the DC superposition characteristics, and the width thereof cannot be increased. In particular, the width of the inductor has recently been miniaturized and mass production of products having a thickness of 1 mm or less is inevitably limited. Accordingly, there is a problem in that it is not possible to provide various types of inductance and DC superposition characteristics.

In addition, the oxide ferrite system has a high permeability and high electrical resistance, but has a low saturation magnetic flux density, which causes a large decrease in inductance due to magnetic saturation and poor DC superposition characteristics.

In addition, when the oxide ferrite-based magnetic material is processed, the strength is weak, and there is a big limitation in sufficient width and slimness.

In addition, the power inductor requires a high DC superposition characteristic because a relatively high current is applied, in the case of the conventional oxide ferrite-based power inductor, it was not effective due to the low DC superposition.

In addition, the leakage magnetic flux generated in the power inductor causes a lot of problems caused by induction heating of the conductive material constituting the circuit. In the case of the conventional multilayer power inductor, a separate nonmagnetic layer is formed to secure a DC superposition characteristic. As a result, there is a problem in that noise caused by leakage magnetic flux is generated between layers.

On the other hand, in the case of Ni-based, Ni-Zn-based, Ni-Zn-Cu-based materials, which are ferrite-based magnetic materials, the operating frequency is stably operated only at 2 to 3 MHz or less.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an ultra-thin power inductor without leakage flux and without limitation of current due to magnetic saturation.

In addition, an object of the present invention is to provide a large-capacity ultra-thin power inductor having a thickness of several tens to hundreds of micrometers without limiting the width.

It is also an object of the present invention to provide an ultra-thin power inductor having a closed circuit of a structure free from leakage magnetic flux.

In addition, an object of the present invention is to provide an ultra-thin power inductor having a certain level of ductility and rigidity, and excellent in mechanical properties.

In order to achieve the above object, the present invention is to form a circuit on each of the upper and lower surfaces of the magnetic sheet in which the powder is dispersed, the upper circuit and the lower circuit is an ultra-thin power inductor is conducted through the via hole, the powder of the magnetic sheet It provides an ultra-thin power inductor, characterized in that the soft magnetic metal alloy powder.

The present invention also provides an ultra-thin power inductor further comprising a magnetic sheet on top of the above-mentioned ultra-thin power inductor.

In addition, the present invention provides an ultra-thin power inductor, wherein the soft magnetic metal alloy powder has anisotropy, and the metal alloy powder is arranged parallel or perpendicular to the magnetic sheet surface.

It is possible to obtain a high use frequency and a large saturation current that a conventional multilayer power inductor could not implement, and to provide an inductor that is thin and not limited in width by using a soft magnetic metal alloy powder sheet.

Therefore, the present invention can be effectively used for miniaturization of electronic products such as slim notebooks, handbooks, and display devices.

Hereinafter, the present invention will be described with reference to the drawings.

2 is a schematic diagram of an ultra-thin power inductor of the present invention.

For the same parts, reference numerals will be omitted to avoid redundancy.

The pattern circuits 20 and 30 separately manufactured are attached to the upper and lower surfaces of the magnetic sheet 10 produced by the present invention to form one layer.

At this time, the magnetic sheet 10 is formed using a soft magnetic metal alloy powder.

The soft magnetic metal alloy powder may be an anisotropic or isotropic powder in the form of flat flakes.

In addition, as the material of the alloy powder, molybdenum permalloy (Mo-permalloy), permalloy (Permalloy), sand dust (Fe-Si-Al alloy), iron-silicon alloy and the like can be used.

The pattern circuit 10 may be implemented using copper or a conductive material, and may be separately manufactured by a conventional method.

At this time, since a large number of pattern circuits are implemented in a predetermined area, it is economically advantageous.

The pre-made magnetic sheet 10 and the pre-fabricated pattern circuits 20 and 30 attach the pattern circuits 20 and 30 to the upper and lower surfaces of the magnetic sheet 10 through isotropic thermocompression bonding.

At this time, in order to improve the adhesion between the magnetic sheet and the pattern circuit, a solution in which a coupling agent is diluted in a solvent, a polymer adhesive or a polymer diluted in the solvent is spray coated.

At this time, a pattern circuit formed on the upper and lower surfaces of the magnetic sheet 10 by drilling a hole in the magnetic sheet 10, applying a conductive material to the hole, or plating the inside in order to conduct each superimposed pattern circuit 10. 20 and 30 can be made conductive.

As described above, the formed ultra thin power inductor is referred to as an open letter ultra thin power inductor 1.

In addition, as described in FIG. 3, the present invention may further configure a closed furnace by stacking a magnetic sheet 40 on top of an open-type ultra-thin power inductor. The ultra thin power inductor formed as shown in FIG. 3 is called a closed-type ultra thin power inductor 2.

The closed-loop ultra-thin power inductor 2 has an effect of minimizing leakage magnetic flux.

4 and 5 are cross-sectional views when the inductor of FIG. 2 is cut in the thickness direction, and is an explanatory view for explaining the arrangement form of the soft magnetic metal powder in the magnetic sheet 10 of the present invention.

Reference numeral 13 in FIGS. 4 and 5 schematically shows a magnetic path generated in the inductor.

In FIG. 4, the anisotropic alloy powder 12 is arranged so as to be perpendicular to the magnetic path 13 generated in the magnetic sheet 10.

5, the anisotropic alloy powder 12 is arrange | positioned so that it may be parallel to the magnetic path 13 which arises in the magnetic sheet 10. In addition, in FIG.

4 and 5, since fine intervals are dispersed in the soft magnetic metal powder, high DC superposition characteristics are exhibited.

Hereinafter, the manufacturing method of this invention is demonstrated.

First, a soft magnetic metal powder having anisotropy is prepared so that the optimum characteristics of the inductor are implemented according to the magnetic path.

To prepare the anisotropic powder, the soft magnetic metal powder is prepared in flake form by milling in an Attrition mill.

The powder is dispersed in a polymer resin system at high density to prepare a magnetic sheet.

A circuit implemented by using a conductive material is formed on the upper surface of the magnetic sheet, and at this time, a number of inductors can be manufactured to arrange a circuit capable of manufacturing an economical efficiency.

A magnetic sheet may be additionally stacked on top of the magnetic sheet on which the pattern circuit is configured to manufacture a closed-type ultra-thin power inductor.

A via hole is formed in the laminated inductor so that the pattern circuit between the layers can be conducted, and the conductive circuit is conducted using plating or conductive paste.

The finished product is cut consistently to the required size.

In order to ensure reliability, the cutting surface is applied by dipping or using a roller.

Through this, the ultra-thin power inductor of the present invention may have a sufficient thermal conductivity, it may be possible to secure the ductility.

Example 1

In the case of open-type ultra-thin inductors, after dispersing sand dust flakes with an average particle diameter of 70 μm in an attrition mill for 6 hours and sanding flakes with an organic polymer matrix material at a weight ratio of 8: 2, the doctor A green sheet having a thickness of 100 μm is produced by the blade method.

In addition, 1-10 sheets of the prepared green sheet and a copper foil (Cu foil) having a thickness of 70um are laminated together and thermostatically pressed at 160 ° C./1 hour and 40 kgf pressure.

A via hole is formed in a 70 μm thick copper foil (Cu foil) thermocompressed on the surface of the green sheet using a drill, and then the via hole is conducted using plating. Subsequently, a circuit and a terminal are realized by chemical etching with an iron chloride solution at an etching temperature of 50 ° C.

The finished product is cut to regular size with precision cutter. In addition, heat-resistant epoxy is applied to the cut surface to ensure reliability.

Example 2

In the case of the closed-type ultra-thin power inductor, sand dust flakes prepared by milling sand dust powder having an average particle diameter of 70 μm in an attrition mill for 6 hours and EPDM applied as an organic polymer matrix material are dispersed in a weight ratio of 8: 2. A green sheet having a thickness of 100 µm was manufactured by the doctor blade method.

In addition, 1-10 sheets of the manufactured green sheets and a copper foil (Cu foil) having a thickness of 70um are laminated together and thermostatically pressed at 160 ° C./1 hour and 40 kgf pressure.

A via hole is formed in a 70 μm thick copper foil (Cu foil) thermocompressed on the surface of the green sheet using a drill, and then the via hole is conducted using plating. Subsequently, a circuit and a terminal are realized by chemical etching with an iron chloride solution at an etching temperature of 50 ° C.

Thereafter, 1 to 5 sheets of green sheets prepared on the opposite side of the terminal are thermally compressed in an equal direction at 160 ° C./1 hour and 40 kgf pressure.

The finished product is cut to regular size with precision cutter. In addition, heat-resistant epoxy is applied to the cut surface to ensure reliability.

Example 3

First, a power inductor is prepared in the same manner as in the second embodiment.

In addition, by adding a 30 μm thick conductive foil on top of the ultra-thin power inductor, the thermal characteristics of the inductor can be improved by maximizing heat dissipation.

Nickel, copper, aluminum, silver, tin, tungsten, or the like may be used as the material of the conductive foil, and is not particularly limited to the material.

Example 4

Sand dust flakes prepared by milling sand dust powder with an average particle diameter of 70 µm for 6 hours in an attrition mill and EPDM applied to an organic polymer matrix material were dispersed at a weight ratio of 8: 2, followed by a doctor blade method. Manufacture green sheet.

In addition, 1-10 sheets of the prepared green sheet and a copper foil (Cu foil) having a thickness of 70um are laminated together and thermostatically pressed at 160 ° C./1 hour and 40 kgf pressure.

A via hole is formed in a 70 μm thick copper foil (Cu foil) that is thermocompressed on the surface of the green sheet by using a drill, and then conducts the via hole using plating. Subsequently, a circuit and a terminal are realized by chemical etching with an iron chloride solution at an etching temperature of 50 ° C.

The 100 μm green sheet is placed between each of the manufactured ultra-thin inductors, and then formed into a multilayer by isothermally pressing at 160 ° C./1 hour and 40 kgf pressure.

In order to electrically connect the power inductors of each layer, via holes are formed using a drill and then the via holes are conducted using plating.

The finished product is cut to regular size with precision cutter. In addition, heat-resistant epoxy is applied to the cut surface to ensure reliability.

Based on the above-described method, an open-type ultra thin power inductor (Example 1), a closed-type ultra thin power inductor (Example 2), and an inductor in which copper foil was added on top of the closed-type ultra thin power inductor (Example 3) And a closed multilayer multilayer ultra thin inductor (Example 4) was prepared.

In addition, an open strip core inductor (Comparative Example 1) and a closed strip core inductor (Comparative Example 2) were formed by winding a conductor around a ferrite magnetic core.

Inductors manufactured according to Examples 1 and 2 and Comparative Examples 1 and 2 were measured using an impedance analyzer (HP 4294A) in a frequency band of 1 KHz to 100 MHz, and a saturation current was measured using an LCR meter (HP 4284A). ) Was measured.

In addition, the saturation current refers to a current value when the DC bias is reduced by 30%, and the allowable frequency refers to a switching frequency range that is allowed within 20% of the initial value when the switching frequency is increased.

The results shown by the above measurement method are shown in Table 1 and in the graphs of FIGS. 6 and 7.

Comparison to the same area
(10mm X 10mm X 1.0mm HT) inductance Saturation Current Allowable frequency Rising temperature Comparative Example 1 10 uH 1 A 10 MHz 40 ℃ Comparative Example 2 10 uH 2 A 5 MHz 40 ℃ Example 1 10 uH 4 A 50 MHz 40 ℃ Example 2 10 uH 3 A 50 MHz 40 ℃ Example 3 10 uH 4 A 50 MHz 32 ℃ Example 4 10 uH 4 A 50 MHz 40 ℃

As shown in Table 1 and FIG. 7, when the frequency increases, Comparative Examples 1 and 2 suddenly increase inductance within a maximum of 10 MHz, while Examples 1 and 2 show a change in inductance around 10 MHz. No inductance changes around 100 MHz.

In Examples 1 and 2, the inductance increases in a state exceeding 10 MHz, so the allowable frequency is very high.

In addition, as described in FIG. 8, Comparative Example 1 and Comparative Example 2 were already saturated around 1.0 A, but it can be seen that Examples 1 and 2 exhibited higher saturation currents.

In addition, in Example 3, it turns out that rising temperature is markedly 32 degreeC with respect to the same saturation current.

In the case where the copper foil is further formed on the ultra-thin power inductor, the heat dissipation effect can be increased to improve the temperature characteristics required by the power inductor, thereby greatly improving the reliability of the inductor.

1 is a perspective view of a conventional wire-wound power inductor.

2 is a perspective view of an open-type ultra-thin power inductor according to the present invention.

3 is a perspective view of the closed-type ultra-thin power inductor according to the present invention.

4 is an explanatory diagram in the case where the anisotropic powder of the magnetic sheet according to the present invention is arranged perpendicular to the direction of the furnace.

5 is an explanatory diagram when the anisotropic powder of the magnetic sheet according to the present invention is arranged horizontally in the direction of the furnace.

6 is a perspective view of a multi-layer ultra-thin power inductor in which ultra-thin power inductors are stacked in multiple layers according to the present invention.

7 is a graph showing a change in inductance according to the frequency of the power inductor of the embodiment and the comparative example according to the present invention.

8 is a graph showing a change in inductance according to the current of the power inductor of the embodiment and the comparative example according to the present invention.

Claims (6)

Circuits are formed on the upper and lower surfaces of the magnetic sheet in which the powder is dispersed, The upper circuit and the lower circuit are ultra-thin power inductors conducting through via holes, The powder of the magnetic sheet is an anisotropic soft magnetic metal alloy powder, arranged in parallel or perpendicular to the magnetic sheet surface, The ultra-thin power inductor further comprises a conductive foil on top of the ultra-thin power inductor. The ultra-thin power inductor of claim 1, further comprising a magnetic sheet on top of the ultra-thin power inductor. delete delete delete The multilayer ultra thin power inductor formed by laminating | stacking many ultra-thin inductors of Claim 1 or 2.

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