KR20210011874A - Soft magnetic alloy powder and electronic parts using the same - Google Patents

Abstract

Provided is a soft magnetic alloy powder that enables use of electronic components in a high-temperature environment. According to the present invention, it is possible to obtain a soft magnetic alloy powder containing 1.2 to 8 wt% of Si, 0 to 9 wt% of Cr, 0.75 to 1.25 wt% of Al, and the remaining of Fe and unavoidable impurities, wherein the soft magnetic alloy powder has a negative iron loss temperature characteristic at 25°C to 150°C.

Description

Soft magnetic alloy powder and electronic parts using the same

The present invention relates to a soft magnetic alloy powder and an electronic component using the same.

The soft magnetic alloy powder is widely used in various electronic components such as inductors. For example, in recent years, as a power inductor used in a power supply circuit, a soft magnetic material that can be used at a high current and high frequency is preferable because of the demand for miniaturization and reduction in power. Conventionally, a ferritic material, which is an oxide, has been used as a main material of an inductor, but it is disadvantageous for miniaturization because of low saturation magnetization. Therefore, in recent years, the number of metal inductors using alloy-based materials having high saturation magnetization and advantageous for miniaturization and reduction in size has increased rapidly. As a metal inductor, a soft magnetic alloy powder made of iron as a main material is used, and a powdered magnetic core formed by compression molding by mixing a soft magnetic alloy powder and a resin is known.

Amid increasing interest in energy issues, electrification of automobiles and power savings in electronics are being promoted, and electronic components that can be made smaller and have less energy loss are required. Specifically, for example, in automobiles, in order to cope with the advancement of control for realizing high environmental performance and driving performance, ``mechanism integration'' in which ECU (Electronic Control Unit) is mounted on actuators such as motors and solenoids is in progress. have. For this reason, there is a growing demand to install an ECU in an engine room, which is a higher temperature environment, and there is a demand for a metal powder core for an ECU usable in a higher temperature environment.

It is known that in conventional electronic components such as a powdered magnetic core using soft magnetic alloy powder, the core loss increases with an increase in temperature, and the temperature of the core itself increases due to heat generated by the core loss during use. Due to this temperature increase, core loss increases and heat generation increases, and thermal runaway may occur by repeating this. For this reason, it has been studied to improve the temperature characteristics of core loss in a high temperature region. For example, in Patent Document 1, heat treatment is performed on a molded article obtained by press-molding a Fe-Si-Al alloy powder having a specific composition, and in Cited Document 2, a Fe-Si-Al alloy powder having a specific composition Each of the soft magnetic alloy powders in which an insulating film is formed on the surface of is described. However, since the Fe-Si-Al alloy powder is hard and lacks plastic deformability, high-density molding is difficult, and it is difficult to obtain a high saturation magnetic flux density advantageous for miniaturization of electronic parts.

Patent Document 1: International Publication No. 2011/016207 Patent Document 2: Japanese Patent Laid-Open Publication No. 2012-9825

An object of the present invention is to provide a soft magnetic alloy powder that enables use of an electronic component in a high-temperature environment, and further, to provide an electronic component.

As a result of conducting various studies, the inventors of the present invention have found a composition of an iron-based soft magnetic alloy having a negative iron loss temperature characteristic, and have come to complete the present invention.

That is, the present invention is a soft magnetic alloy powder containing Si: 1.2 to 8% by weight, Cr: 0 to 9% by weight, and Al: 0.75 to 1.25% by weight, and the balance being Fe and inevitable impurities, 25°C It is a soft magnetic alloy powder having a negative iron loss temperature characteristic at -150°C.

According to an aspect of the present invention, the soft magnetic alloy powder is provided, including Si: 1.5 to 7.5% by weight, Cr: 0 to 8.5% by weight, and Al: 0.8 to 1.2% by weight.

According to one aspect of the present invention, the soft magnetic alloy powder having a particle diameter (D50) of 0.5 to 50 μm is provided.

According to an aspect of the present invention, the soft magnetic alloy powder further comprising Ca: 0.001 to 0.02% by weight is provided.

According to one aspect of the present invention, the soft magnetic alloy powder containing Ca: 0.002 to 0.01% by weight is provided.

According to an aspect of the present invention, an electronic component including the soft magnetic alloy powder is provided.

According to an aspect of the present invention, the electronic component is provided, which is a powdered magnetic core, an electromagnetic wave absorbing shield or an electromagnetic wave absorber.

According to an aspect of the present invention, there is provided a method for manufacturing an electronic component, comprising pressing the soft magnetic alloy powder.

According to an aspect of the present invention, there is provided a method for manufacturing an electronic component comprising injection molding the soft magnetic alloy powder.

The present invention can provide a soft magnetic alloy powder that enables use of an electronic component in a high temperature environment.

Hereinafter, an embodiment of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be carried out with appropriate changes within a range that does not impair the effects of the present invention. In addition, in the following description, "A to B" means "A or more and B or less."

The soft magnetic alloy powder according to the present embodiment contains 1.2 to 8% by weight of Si, preferably 1.5 to 7.5% by weight, 0 to 9% by weight of Cr, preferably 0 to 8.5% by weight, and 0.75 to Al. 1.25% by weight, preferably 0.8 to 1.2% by weight, the balance being Fe and unavoidable impurities. By having a composition containing the above positive Si, Cr and Al, the soft magnetic alloy powder has a negative iron loss temperature characteristic at 25°C to 150°C. By having this characteristic, the soft magnetic alloy powder according to the present embodiment is suitably used as a material for an electronic component used at the time of use in a high temperature environment.

[Other elements]

The soft magnetic alloy powder according to the present embodiment may contain elements such as N, S, O, etc. as unavoidable impurities, so as not to affect target properties.

[Negative iron loss temperature characteristics]

The negative iron loss temperature characteristic refers to a characteristic in which the iron loss of the soft magnetic alloy powder has a negative coefficient with respect to temperature, that is, the iron loss of the soft magnetic alloy powder decreases with an increase in temperature. In the soft magnetic alloy powder according to the present embodiment having a negative iron loss temperature characteristic, since the core loss decreases with the increase in temperature, the increase in the temperature of the core itself due to heat generation due to the core loss during use is suppressed. As a result, it has properties suitable as a material for electronic components used in a high temperature environment, which has been difficult in the past. It is believed that the reason why the soft magnetic alloy powder according to the present embodiment has a negative iron loss temperature characteristic is that the magnetostriction constant determined according to the composition has a positive value.

It is preferable that the soft magnetic alloy powder according to the present embodiment has a particle diameter (D50) of 0.5 to 50 μm. The "particle diameter" means a median diameter: D50, and is measured by a conventionally known method, for example, a laser diffraction-scattering method. The effects on the saturation magnetic flux density (Bs), permeability, and negative iron loss temperature characteristics of the soft magnetic alloy powder described above are obtained from a soft magnetic alloy powder having a wide particle diameter, with a particle diameter (D50) of 0.5 to 50 μm, preferably Is 0.5 to 40 μm, more preferably 0.5 to 25 μm, and still more preferably 1.0 to 20 μm, so that a particularly high effect can be obtained.

The soft magnetic alloy powder according to the present embodiment preferably further contains Ca, and contains 0.001 to 0.02% by weight, preferably 0.002 to 0.01% by weight of Ca. By including Ca in a trace amount, the permeability of the soft magnetic alloy powder is improved or the iron loss is decreased. By the presence of Ca in the above range, the iron-based soft magnetic alloy powder has a low specific surface area, thereby reducing the amount of oxygen in the powder. This is considered to be a result of a change in the surface tension of the molten metal for producing an alloy powder or a change in the amount of oxygen in the molten metal due to Ca having a high affinity for oxygen. Moreover, as with Ca, if it is an element having high affinity with oxygen, the same effect as in the case of Ca can be exhibited.

[Method of manufacturing soft magnetic alloy powder]

The soft magnetic alloy powder according to the present embodiment can be produced by a conventionally known method exemplified below as a method for producing a metal powder, but since it has the above-described magnetic properties when it has the composition of this embodiment, the production method is specifically Not limited.

・Atomization method: Water atomization method, gas atomization method, centrifugal force atomization method, etc.

Mechanical process method: grinding method, mechanical alloy method, etc.

·Melt spinning method

·Rotation electrolysis (REP method): Plasma REP method, etc.

Chemical process method: oxide reduction method, chloride reduction method, wet metallurgy technology, carbonyl reaction method, etc.

Among the manufacturing methods exemplified above, in particular, the atomization method can mass-produce small-diameter and spherical soft magnetic alloy powder under atmospheric pressure. Among them, if the water atomization method is employed, it can be produced at low cost.

In the case of producing soft magnetic alloy powder using the water atomization method, the molten metal is scattered by spraying high-pressure water with parameters set so that the desired cooling conditions and particle diameters are dissolved to the molten metal in which the material adjusted to the desired composition is dissolved. It can be solidified to obtain a powder. After that, the obtained powder is dried and classified, and if necessary, surface treatment is performed to obtain the target soft magnetic alloy powder.

When Ca is added, it is carried out by adding Ca in the form of a metal to the molten metal, and the order of addition is irrespective of the order of addition, but since Ca tends to become an oxide, it is necessary to add a certain excess of Ca to the target alloy composition. Need something.

The electronic component according to the present embodiment contains the soft magnetic alloy powder described above. The electronic parts according to the present embodiment are used in a wide variety of industrial fields, such as transportation equipment such as automobiles, as not only electronic parts generally used such as motors, reactors, and transformers, but also electronic valves, solenoids, sensors, etc. It is an electronic component. Furthermore, the electronic component according to the present embodiment is an electromagnetic wave absorption shield or electromagnetic wave absorber used for the purpose of absorbing electromagnetic waves of a specific frequency.

The electronic component according to the present embodiment is a powdered magnetic core, an electromagnetic wave absorbing shield, or an electromagnetic wave absorber.

The powdered magnetic core, the electromagnetic wave absorbing shield, or the electromagnetic wave absorber according to the present embodiment contains the soft magnetic alloy powder described above. Preferably, the green magnetic core according to the present embodiment contains a soft magnetic alloy powder in a granulated form mixed with a resin that imparts insulation or molding processability. Preferably, in the electromagnetic wave absorption shield according to the present embodiment, a paste prepared by mixing soft magnetic alloy powder, resin, ink, and the like is applied to at least a part of the paste. Preferably, in the electromagnetic wave absorber according to the present embodiment, a sheet formed by mixing soft magnetic alloy powder, resin, rubber, and the like to have a desired thickness is affixed to at least a part of the sheet.

The powdered magnetic core according to this embodiment is, for example,

Forming a film on the surface of the soft magnetic alloy powder to obtain granulated powder,

Step of obtaining a molded body by pressing granulated powder,

The process of heat treating the molded body,

It is manufactured by a method comprising a.

In the step of obtaining the granulated powder, a film is formed of a conventionally known resin, such as an epoxy resin, a silicone resin, an acrylic resin, or the like, in order to impart the desired insulation, corrosion resistance, and the like.

The temperature in the heat treatment process is 550°C to 950°C, preferably 600°C to 900°C. In addition, the heating time is preferably about 30 minutes to 2 hours. Deformation is introduced into the soft magnetic alloy powder constituting the molded body before heat treatment by pressure molding. This deformation causes a decrease in permeability or an increase in hysteresis loss, which is one of the factors of iron loss. Therefore, by heat-treating the molded body under the above conditions, the deformation can be sufficiently removed. The heat treatment is preferably performed in an inert gas atmosphere such as a nitrogen atmosphere or a reduced pressure atmosphere.

The electronic component manufacturing method according to the present embodiment includes injection molding the soft magnetic alloy powder described above. By injection molding, it can be molded into a complex shape with high precision. After the molding process, if necessary, degreasing, heat treatment, or the like is performed to obtain an electronic component having a desired shape and characteristics.

Example

Examples of the present invention are shown below. The content of the present invention is not interpreted as being limited by these examples.

[Production of soft magnetic alloy powder]

The material adjusted to each composition shown in Tables 1 and 2 was dissolved in a high-frequency induction furnace, and a soft magnetic alloy powder was obtained using a water atomization method. The conditions of the water atomization method are as follows.

<Water atomization conditions>

Water pressure: 100 MPa

·Quantity: 100L/min

·Water temperature: 20℃

·Orifice diameter: φ4mm

·Melt temperature: 1800℃

The obtained soft magnetic alloy powder was dried with a vibration vacuum dryer (VU-60: manufactured by Chuokakoki). Drying conditions are as follows.

<Drying conditions>

·Temperature 100℃

Pressure 10 kPa or less

・Time 60 minutes

Quantitative analysis of the composition of the soft magnetic alloy powder after drying was performed with an ICP emission analyzer [SPS3500DD: manufactured by Hitachi High-Tech Science].

The soft magnetic alloy powder after drying was classified by an air classifier (turbo classifier: manufactured by Nissin Engineering) to obtain the target soft magnetic alloy powder. The particle diameter (D50) of the obtained soft magnetic alloy powder was measured using a wet particle size analyzer [MT3300EX II: manufactured by Microtrac-Bell].

[Preparation of sample]

Each soft magnetic alloy powder prepared as described above was mixed with an epoxy resin to prepare a granulated powder. The blending amount of the soft magnetic alloy powder and the epoxy resin was soft magnetic alloy powder: epoxy resin = 97:3 by weight ratio.

Each granulated powder was compacted into a ring shape (molding pressure: 500 MPa) to prepare a compact magnetic core (outer diameter: 15 mm, inner diameter: 9 mm, thickness: 3 mm).

Each of the powdered magnetic cores was evaluated as follows.

A toroidal core in which a copper wire having a wire diameter: 0.3 mm was wound by a bifilament core was prepared as an evaluation sample. Iron loss was measured in a temperature range of 25°C to 150°C using a BH analyzer [SY8258: manufactured by Iwatsu Measurement] under conditions of a measurement frequency: 1 MHz and a maximum magnetic flux density: 25 mT. Subsequently, the magnetic permeability was measured at a temperature of 150° C. under the conditions of a measurement frequency: 1 MHz and a maximum magnetic flux density: 10 mT.

[Evaluation results]

The evaluation results are shown in Tables 1 and 2.

Symbols of ○, △, and × in "Temperature Characteristics" in Tables 1 and 2 indicate that when the iron loss increases with increasing temperature, it has negative iron loss temperature characteristics in the temperature range of ×, 25°C to 120°C, but 120°C. When the iron loss is increased in the temperature range exceeding △, it means that the case has negative iron loss temperature characteristics in the temperature range of 120°C to 150°C, and the case where the iron loss does not increase is ○.

Symbols of ◎, ○, △ and × in "magnetic properties" in Tables 1 and 2 compare the magnetic permeability and iron loss at 150°C with the same D50 and the same composition excluding Al and Ca. (For example, Examples 1-(1) to 1-(11) are Comparative Example 1, Examples 2-(1) to 2-(11) are comparisons with Comparative Example 2, and Example 5 From 12 are comparisons with Comparative Examples 5 to 12, respectively). The evaluation criteria are as follows.

×… When both the permeability and iron loss are not improved

△... When only one of the permeability or iron loss is improved

○… When both permeability or iron loss are improved

◎… When both the permeability or iron loss are improved by 20% or more

Here, the improvement of the permeability means an increase in the measured value of the permeability, and the improvement of the iron loss means a decrease in the iron loss.

As shown in Tables 1 and 2, the powdered magnetic core using the soft magnetic alloy powder according to the examples surprisingly has negative iron loss in not only a temperature range of 25°C to 120°C, but also a very high temperature range of 120°C to 150°C. It has a temperature characteristic. In addition, the powdered magnetic core using the soft magnetic alloy powder according to the example was surprisingly compared to the powdered magnetic core using the soft magnetic alloy powder (conventional Fe-Si-based alloy powder, Fe-Si-Cr-based alloy) according to the comparative example. At a very high temperature of 150° C., at least one of the permeability and iron loss is improved. That is, the soft magnetic alloy powder of the present invention has excellent properties as an electronic component usable in a high temperature environment, particularly as a material for a powdered magnetic core.

Further, the powdered magnetic core using the soft magnetic alloy powder to which Ca is added, surprisingly, has improved permeability and iron loss compared to the powdered magnetic core using the soft magnetic alloy powder to which Ca is not added.

As shown in Tables 1 and 2, it can be seen that the present invention exhibits the above-described effects without depending on the particle diameter (D50) of the powder.

As described above, the soft magnetic alloy powder of the present invention has excellent properties that enable use of electronic components in a high temperature environment.

(Modification example)

In the above examples, as an electronic component using the soft magnetic alloy powder of one embodiment, a powdered magnetic core manufactured by pressure molding has been described as an example, but one embodiment is not limited to this example. For example, it is an electronic component manufactured by injection molding. It is also clear from the results of the above examples that the electronic component in which the soft magnetic alloy powder of the present invention having negative iron loss temperature characteristics is used can be suitably used in a high temperature environment.

As another example of the electronic component of one embodiment, an electromagnetic wave absorbing shield and an electromagnetic wave absorber may be mentioned. The electromagnetic wave absorption shield is used for the purpose of cutting electromagnetic waves of a specific frequency, and is installed, for example, in a case of a mobile device such as a mobile phone. The electromagnetic wave-absorbing shield can be obtained by preparing and mixing magnetic powder, resin, ink, and the like so as to obtain desired properties to form a paste, and applying the paste to an adapted location. In addition, when producing a paste, vacuum defoaming may be performed in order to promote dispersion of the magnetic powder.

The electromagnetic wave absorber is used for the purpose of cutting electromagnetic waves of a specific frequency, and is used, for example, in a radio wave darkroom used in a gate of an ETC (electronic toll collection system) or an EMC test. The electromagnetic wave absorber can be obtained by preparing and mixing magnetic powder, resin, and rubber so as to obtain desired properties, forming a sheet shape, and attaching the sheet to an adaptation site.

Claims (9)

Si: 1.2 to 8% by weight,
Cr: 0 to 9% by weight, and
Al: 0.75 to 1.25% by weight
Including, and the balance as a soft magnetic alloy powder of Fe and inevitable impurities,
A soft magnetic alloy powder having a negative iron loss temperature characteristic at 25°C to 150°C. The method according to claim 1,
Si: 1.5 to 7.5% by weight,
Cr: 0 to 8.5% by weight, and
Al: 0.8 to 1.2% by weight
Containing, soft magnetic alloy powder. The method according to claim 1 or 2,
A soft magnetic alloy powder with a particle diameter (D50) of 0.5 to 50 μm. The method according to any one of claims 1 to 3,
Ca: soft magnetic alloy powder further containing 0.001 to 0.02% by weight. The method of claim 4,
Ca: soft magnetic alloy powder containing 0.002 to 0.01% by weight. An electronic component containing the soft magnetic alloy powder according to any one of claims 1 to 5. The method of claim 6,
An electronic component, a powdered magnetic core, an electromagnetic wave absorbing shield or an electromagnetic wave absorber. A method for manufacturing an electronic component, comprising pressing the soft magnetic alloy powder according to any one of claims 1 to 5. A method for manufacturing an electronic component, comprising injection molding the soft magnetic alloy powder according to any one of claims 1 to 5.