JPH06132128A - Amorphous soft magnetic lamination film - Google Patents

Abstract

PURPOSE:To realize an amorphous soft magnetic lamination film of good high- frequency magnetic characteristics and handling property by laminating a plurality of amorphous soft magnetic layers formed by electrolysis or nonelectrolysis and oxide layers formed by electrolysis oxidation method alternately. CONSTITUTION:Water solution containing each element of ferrous chloride, cobalt sulfate, boric acid and phosphorous acid is used as electrolyte, a stainless steel is used as an electrode, and electrolytic deposition is performed. A deposit layer 1 has a film thickness of several mum and amorphous property is recognized through measurement of X-ray diffraction. Then, anode oxidation is carried out with H2SO4 solution on Ag/AgCl basis, and an oxide insulation layer 2 whose surface color is changed to thin dark brown is formed. After the operation is repeated six times, the deposited layers are peeled off from an electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous soft magnetic laminated film. The present invention particularly relates to a soft magnetic material that is used for magnetic parts used in various electronic devices and industrial devices and exhibits excellent properties.

[0002]

2. Description of the Related Art In recent years, technological innovation in electronics has been remarkable, and miniaturization, weight reduction and high density of electronic devices have become a central issue in the technology. In miniaturization of electronic equipment, improvement of the inductor element is one of the factors.
For example, in a switching power supply using a magnetic amplifier,
It is expected that the power supply can be dramatically reduced in size by increasing the switching frequency. Further, it is required that the magnetic material that constitutes the inductor element with higher frequency has better high frequency characteristics than ever.

In order to obtain a magnetic material having excellent high frequency characteristics, it is necessary to minimize the magnetic loss. The magnetic loss at high frequency is mainly controlled by the eddy current loss and is represented by the following equation.

[0004]

[Equation 1]

As is clear from this equation, it is understood that the higher the electrical resistivity of the material and the thinner the material, the smaller the magnetic loss. At present, as one of the materials with the highest high frequency characteristics,
Examples include ferrite. In the case of ferrite, since it is insulating, it has a small eddy current and good characteristics at high frequencies. However, the soft magnetic characteristics, such as saturation magnetic flux density and magnetic permeability, are not at a high level, and are rather inferior to other materials. Recently, a method for producing an amorphous alloy by a rapid cooling method has been developed, and an excellent soft magnetic material has been obtained. Since such a material has a relatively high electric resistivity and various characteristics, it is now widely used as a magnetic component such as an inductor element. The method of producing an amorphous alloy by the rapid cooling method is to guide the molten metal to a cooled rotating roll,
Quenching at 10 ⁵ to 10 ⁶ deg / s solidifies without giving time for crystallization to form an amorphous alloy. However, the amorphous alloy produced by the quenching method is currently limited to a thickness of several tens of μm or more due to the production method. This is because when the molten metal comes into contact with the cooling roll, unevenness occurs on the surface and it is difficult to form a thin film. As can be seen from the equation (1), making the thickness thinner is an effective means for obtaining a material with good characteristics, but the quenching method has its limits.

On the other hand, as a method for producing a thin film amorphous alloy, a sputtering method, a vacuum vapor deposition method, an ion plating method and the like have been studied. However, these methods have a slow deposition rate, are poor in productivity, require special equipment, and require a large capital investment. Therefore, it is not suitable for mass production at a lower cost.

On the other hand, a method for producing an amorphous alloy using electrolytic plating and electroless plating has also been studied (Japanese Patent Laid-Open No. Sho 5).
2-140403 and JP-A-55-16409.
No. 2). The present applicant has disclosed an iron-cobalt amorphous alloy foil which is excellent in soft magnetism and is much thinner than conventional amorphous alloys by using a plating method (Japanese Patent Laid-Open No. Hei.
No. 126889). This alloy has a thickness of several μm, and because of its thin film thickness, it has excellent magnetic properties at high frequencies.

[0008]

However, if the magnetic film becomes too thin, the handling becomes difficult. For example, during manufacturing, plating is continuously performed, and then the thin film is peeled off from the electrode. However, when the magnetic film becomes too thin, the film is sometimes cut. Further, when a thin film is used for a toroidal core as an application to a magnetic component, if the film is thin, it cannot be wound well around the core, and voids are generated between the films in the core. Thus, if the magnetic film is too thin,
It leaves a problem in workability and cannot manufacture a low-priced product.

The present inventors have made earnest studies on improvement of a magnetic film having a thickness of several μm, which has a problem in workability although it has excellent high-frequency magnetic properties and is difficult to use on an industrial scale. Has reached the present invention.

[0010]

SUMMARY OF THE INVENTION The gist of the present invention is that an amorphous soft magnetic layer formed by an electrolytic or electroless method and an oxide layer formed by an electrolytic oxidation method are alternately laminated in plural layers. The amorphous soft magnetic multilayer film is characterized by being formed. The present invention begins by forming a sufficiently thin amorphous soft magnetic layer excellent in high frequency magnetic characteristics by an electrolytic or electroless method. The amorphous soft magnetic layer itself must have excellent magnetic properties. The magnetic properties of an amorphous alloy are governed by its alloy composition. In order to exhibit the characteristics excellent in soft magnetism, it is necessary to minimize the magnetostriction which is a magnetic characteristic parameter. The magnitude of magnetostriction is closely related to its alloy composition. For example, among compositions exhibiting ferromagnetism, Fe / Co = 6/94, Fe / Ni = 18/82 and Co / Ni = 46/54 are well known as compositions having (magnetostriction) = 0. There is. Of these, Fe / C that provides a relatively high saturation magnetic flux density
The o type is preferable because it is excellent in the composition of the soft magnetic material. In order to obtain an amorphous soft magnetic layer having such an alloy composition as a very thin layer, it is necessary to use an electrolytic or electroless method. As described above, it is difficult to obtain a thickness of 20 to 25 μm or less by the rapid cooling method for producing an amorphous alloy. The thickness of the amorphous soft magnetic layer of the present invention is preferably 1 in order to reduce eddy currents and exhibit excellent high frequency magnetic characteristics.
It is 0 μm or less, more preferably 4 μm or less. As a means for forming an amorphous soft magnetic layer by an electrolytic method, there is disclosed in Japanese Examined Patent Publication No.
A method using hypophosphite or hypophosphite described in JP-A-10233 or a Co group as a main component using phosphorous acid or phosphite described in Japanese Patent Application No. 1-118591. The method of precipitating the amorphous alloy can be used. Japanese Patent Application No. 63-276190
The method described in the publication is suitable. Hypophosphite or borohydride can be used as the reducing agent. Depending on the type of these reducing agents, a semimetal element that stabilizes the amorphous alloy can be selected. Since it is an electroless method, the deposition base material is not limited to conductivity, and any kind of material can be used. If a very thin plastic film is used, the deposited amorphous soft magnetic layer can be wound as it is to form a magnetic core without peeling off.

Next, it is necessary to provide an oxide layer on the surface of the amorphous soft magnetic layer by an electrolytic oxidation method. In general, metal oxides are often insulating substances, and even amorphous alloys containing Co or Fe exhibit high electrical resistance. The laminated film of the present invention is characterized by having a high resistance layer formed by an electrolytic oxidation method on an amorphous soft magnetic surface. This can prevent eddy currents generated at high frequencies. This oxide layer may be very thin. The eddy current can be blocked if there is an insulator in the current path, so that it is effective even if the thickness is thin. The thickness can be made thin to the extent that eddy currents do not leak, and can be made as thin as several thousand Å, preferably several hundred Å, more preferably several tens Å. On the other hand, if the oxide layer is too thick, the oxides of Co and Fe will exhibit hard magnetic properties and the soft magnetic properties will deteriorate.

The electrolytic oxidation is carried out by applying a metal passivation potential by a conventional method. FIG. 1 shows an anodic polarization curve of an amorphous alloy containing Co as a main component. 0.5
The passive substance formation potential in the H ₂ SO ₄ solution of M is Ag · A.
It is 0 to +1.5 V based on gCl, and a potential in this range is applied to the working electrode to perform anodic oxidation. When other electrolytes are used, the passivation potential suitable for each is used. The electrolytic solution may be H ₂ SO ₄ , HCl, HNO ₃
An acidic solution such as, a neutral solution such as Na ₂ SO ₄ or NaCl, an alkaline solution such as NaOH or KOH is used, and a solution of various salts adjusted to an arbitrary pH with a pH adjuster should also be used. You can also

When an amorphous soft magnetic layer is further formed by an electrolytic method on the oxide layer which is a high resistance layer obtained by the electrolytic oxidation method, the galvanostat method is used.
Even if the electrode potential fluctuates due to the surface of the oxide layer, the overvoltage for depositing the amorphous alloy is kept constant, and the composition of the deposited alloy becomes the same as that without the oxide layer. Therefore, by thinning the oxide layer, electrolytic deposition of an amorphous alloy can be easily performed.

Other examples of the method for oxidizing the metal surface include a thermal oxidation method and a solution oxidation method. However, in the thermal oxidation method, since the amorphous alloy has some corrosion resistance,
Oxidation rate is too slow. Further, the solution oxidation method is sensitive to the concentration of the oxidant and the temperature at the time of oxidation, and the controllability of the oxide layer thickness is poor. On the other hand, in the electrolytic oxidation method, the degree of oxidation and the thickness of the oxide layer can be easily adjusted by controlling the applied potential.

In producing the laminated film of the present invention,
In this way, the formation of the oxide layer on the amorphous soft magnetic layer and the formation of the amorphous soft magnetic layer on the oxide layer are repeated, and the laminated film is formed to such an extent that there is no problem in workability in the subsequent steps. Thicken. The amorphous soft magnetic laminated film according to the present invention has a structure as shown in FIGS. 2 (a), 2 (b) and 2 (c). (A) shows the amorphous soft magnetic layer 1 at both ends of the laminated film.
And at least one or more oxide layers 2 are alternately laminated. In this case, when it is used as a single film, it is advantageous in terms of magnetic flux density, but when a laminated film is wound to form a magnetic core or the like, it is necessary to separately provide an insulating layer.
(B) has a structure in which oxide layers 2 are arranged at both ends and alternately laminated, and when wound around the magnetic core, it is not necessary to apply the insulating layer 2, and the amorphous soft magnetic layer 1 is further added. It can be protected by an oxide layer. (C) is a layer in which the amorphous soft magnetic layers 1 and the oxide layers 2 are alternately laminated. Generally, the structure as described above is excellent in versatility.

[0016]

EXAMPLES The present invention will be further described below with reference to examples. Example 1 Ferrous chloride 0.1 mol / l, cobalt sulfate 0.9 mol /
1, boric acid 0.1 mol / l and phosphorous acid 0.1 mol / l
The pH of an aqueous solution containing each component at a concentration of 1 was adjusted to 1.7 and used as an electrolytic solution. The center surface roughness of the electrode is 0.
Using a stainless steel plate having a mirror finish of 5 μm or less, electrolytic deposition was performed at a current density of 0.05 A / cm ² and a temperature of 50 ° C. for 6 minutes. The deposited layer had a film thickness of 2.97μ and was confirmed to be amorphous by X-ray diffraction measurement. Next, add 0.5M H ₂ SO ₄ solution to the Ag / AgCl standard.
A potential of 0.5 V was applied and anodization was performed at 25 ° C. for 30 seconds. The surface was light brown.

After repeating the above operation 6 times, the deposited layer was peeled from the electrode. A film with a total thickness of 19.4μ was obtained. The alloy composition of the film was quantitatively analyzed by using an ICP emission spectrometer (ICAP 575MK type manufactured by Nippon Charel Ash). The results are shown in Table 1. Further, as the magnetic characteristics of this film, the initial magnetic permeability was measured by the following method.
This film was cut into a tape having a width of 5 mm. This magnetic thin film was wound once around a quartz tube having an outer diameter of 10 mm, a length of 5 mm and a thickness of 1 mm, and annealed at 250 ° C. in a nitrogen atmosphere. A 0.5 mm enamel wire was wound around this quartz tube for 15 turns. The inductance was measured with a Model 4275A multi-frequency LCR meter manufactured by Yokogawa Hewlett-Packard Co., Ltd., and the initial permeability was determined by the following formula. However, the frequency was 10 kHz to 10 MHz, and the excitation was measured in terms of 4 mOe.

[0018]

[Equation 2]

Here, L is the inductance (H), ω is 2πf (f: frequency), l is the average magnetic path length (cm), n is the number of windings, and S is the total cross-sectional area (cm ² ) of the magnetic film. is there. The obtained results are shown in FIG.

Comparative Example 1 The same electrolytic solution as in Example 1 was used to electrolytically deposit an amorphous alloy for 6 minutes under the same electrolytic conditions. The composition analysis and the measurement of the initial magnetic permeability of the obtained film were performed in the same manner as in Example 1.
At the time of measuring the initial magnetic permeability, alumina powder (1 μ particle size) was dispersed in one surface of this film in an organic solvent and applied, and then the film was wound around a quartz tube for 7 turns and had a magnetic cross-sectional area almost the same as that of Example 1. And made the measurement error as small as possible. In this case, when wound around a quartz tube, since the magnetic film was thin, it could not be easily wound due to wrinkles or breaks, and the workability was poor. These results are shown in Table 1 and FIG. 3, respectively.

Comparative Example 2 The same electrolytic solution as in Example 1 was used and the same electrolytic conditions were applied.
The amorphous alloy was electrolytically deposited for a minute. The thickness of the obtained film was 19.9 μm. As in Example 1, the initial magnetic permeability was measured by winding the quartz tube once around the circumference. The obtained results are shown in FIG.

[0022]

[Table 1]

As can be seen from Table 1, even if electrolytic deposition is performed on the oxide layer, an amorphous alloy having the same composition can be electrolytically deposited if the current density is constant (note that the fluctuation of the first decimal place is Within the measurement accuracy). As shown in FIG. 3, the 19.9 μ film of Comparative Example 2 is presumed to have a large initial magnetic permeability in the MH _Z band and a large eddy current loss. In 2.97μ film of Comparative Example 1, there is no decrease at all to 10 MHz _Z. The 19.4μ film of Example 1 of the present invention exhibits excellent high-frequency magnetic characteristics, although it shows a slight decrease in the MH _Z band, and it is considered that the eddy current is reduced by the oxide layer at high frequencies.

Comparative Example 3 The same electrolytic solution as in Example 1 was used to carry out electrolytic deposition of an amorphous alloy for 6 minutes under the same electrolytic conditions. The resulting membrane was thermally oxidized in air at 200 ° C. for 30 minutes and 1 hour, respectively.
For each, these operations were repeated 6 times and peeled from the electrode. The thickness of this film was 19.0μ in both cases. These films were hard and brittle. The initial magnetic permeability of this film was measured in the same manner as in Example 1. As can be seen from FIG. 4, even if the thermal oxidation is performed for 1 hour, the high frequency magnetic characteristics are not sufficiently improved.

[0025]

According to the present invention, there is provided an amorphous soft magnetic laminated film having excellent high frequency magnetic characteristics and handleability.

[Brief description of drawings]

FIG. 1 is an anode curve of an amorphous alloy containing Co as a main component.

FIG. 2 is a schematic diagram of a configuration example of an amorphous soft magnetic laminated film according to the present invention.

FIG. 3 is a diagram showing high frequency magnetic characteristics of films obtained in Examples and Comparative Examples.

FIG. 4 is a diagram showing high frequency magnetic characteristics of a film obtained in a comparative example.

[Explanation of Codes] 1 ... Amorphous soft magnetic layer 2 ... Oxide insulating layer

Claims (1)

[Claims] 1. An amorphous soft magnetic layer comprising a plurality of alternating amorphous soft magnetic layers formed by an electrolytic or electroless method and oxide layers formed by an electrolytic oxidation method. Laminated film.