JP2815926B2 - Magnetic core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a noise filter, a saturable reactor, an ultra-small inductance element for reducing spike noise, various transformers, a choke coil, and a zero-phase current transformer. The present invention relates to a magnetic core using an ultra-thin soft magnetic alloy ribbon suitable for applications requiring high frequency and high magnetic permeability used in magnetic heads and the like.

(Prior Art) In recent years, with the demand for smaller and lighter electronic devices and higher performance, magnetic components used as important functional parts also need to have higher performance.

For example, a switching power supply incorporating a magnetic amplifier has been widely used, but a main part of the magnetic amplifier is a saturable reactor, and a magnetic core material having excellent square magnetization characteristics is required. . Also, as described above, as the demand for smaller and lighter electronic devices and higher performance in recent years has increased, there has been a strong demand for smaller and lighter switching power supplies, and in order to achieve this, the switching frequency has been increased to higher frequencies. Is required.
Therefore, it is strongly desired that the core constituting the saturable reactor has a low loss in a high frequency range.

However, Fe-
Sendah (trade name) made of Ni crystalline alloy is 20kH
The eddy current loss significantly increases in a high frequency range of z or more, and is not suitable for use in a high frequency range. Also,
Even in the case of using an amorphous alloy capable of obtaining a low iron loss and a high squareness ratio in a high frequency range, the iron loss increases in a MHz range, so that it is practically limited to about 200 to 500 kHz.

On the other hand, it is generally known that by reducing the thickness of a metal material, the iron loss can be suppressed and the high-frequency characteristics can be improved by reducing the plate thickness. In order to realize a power supply with a frequency of MHz, attempts have been made to further reduce the thickness.

On the other hand, recently, an Fe-based ultrafine crystal alloy having soft magnetic properties almost equivalent to that of a Co-based amorphous alloy has been reported (EP
O Publication No. 0271657, JP-A-63-320504, etc.). This alloy is made of Cu and Nb in Fe-Si-B alloy, etc.
One kind of W, Ta, Zr, Hf, Ti, Mo, etc. is added and once formed as a ribbon similar to an amorphous alloy, and then heat-treated in a temperature range not lower than its crystallization temperature to obtain fine crystals. The grains are deposited.

Even in such Fe-based ultrafine crystal alloys, attempts have been made to reduce the thickness of the sheet in order to improve high-frequency characteristics.

(Problems to be Solved by the Invention) As described above, various magnetic cores are required to have a low iron loss up to a high frequency range (up to a MHz range). It leads to downsizing and higher performance. In order to satisfy such requirements, attempts have been made to make the soft magnetic alloy ribbon constituting the magnetic core extremely thin.

By the way, the magnetic core is usually formed by winding a soft magnetic alloy ribbon such as the Co-based amorphous alloy ribbon or the Fe-based ultrafine alloy ribbon described above. It has been found for the first time by the inventors of the present invention that a new problem occurs when a wound body is formed in the same manner as a soft magnetic alloy ribbon having a thickness of about 20 μm.

In other words, a magnetic core using a soft magnetic alloy ribbon having a thickness of about 20 μm is generally wound so that the packing factor is about 75% to 85%. Is formed of an ultrathin soft magnetic alloy ribbon having a thickness of, for example, 10 μm or less, the stress increases, and the low loss of the ultrathin soft magnetic alloy ribbon cannot be sufficiently utilized.

The present invention has been made based on such knowledge, and has made full use of the characteristic of low loss of an ultrathin soft magnetic alloy ribbon, and has enabled downsizing and practical application to a high frequency range. It is an object to provide a magnetic core.

[Structure of the Invention] (Means and Actions for Solving the Problems) That is, the present invention relates to a magnetic core comprising a winding of a soft magnetic alloy ribbon having a thickness of 10 μm or less, and a packing factor of the winding. Is in the range of 10% to 65%.

Here, the packing factor (Pf) referred to in the present invention indicates a ratio between the actual volume of the soft magnetic alloy ribbon constituting the wound body and the bulk volume of the wound body, and is expressed by the following equation. Things.

As the soft magnetic alloy ribbon used for the magnetic core of the present invention,
For example, a Co-based amorphous alloy ribbon, an Fe-based ultrafine crystal alloy ribbon, and the like are exemplified.

The Co-based amorphous alloy is, for example, one represented by the following general formula.

General _{formula: [(Co 1-a Fe} a) 1-bc M b M 'b] in _{100-xy Si x B y ......} (I) ( wherein, M represents Cr, Mo, W, Cr + Mo, Cr + W, Cr + Mo + W
And M 'represents at least one selected from Nb and Ta, and a, b, c, x and y are numbers satisfying the following formula.

0.03≤a≤0.08 0.02≤b≤0.06 0≤c≤0.03 0.02≤b + c≤0.08 10≤x≤15 (at%) 10≤y≤15 (at%) 23≤x + y≤28 (at%) In the above formula (I), Fe is an element for controlling magnetostriction, and the value of a defining the amount of Fe is set in a range of 0.03 to 0.08. More preferably, it is in the range of 0.04 to 0.07.

M is an effective element for lowering the viscosity at the time of melting the alloy, improving the wettability with the roll, improving the surface properties of the alloy and reducing pinholes. If the amount is too small, the effect of addition cannot be obtained, A good ultra-thin ribbon with few pinholes or the like is difficult to obtain. Conversely, if the amount is too large, the Curie temperature decreases and the effect of addition cannot be improved, so the value of b that defines the amount of M is 0.02 to 0.06. Is preferable. M ′ is an element effective for expanding the heat treatment temperature range by improving the crystallization temperature, improving the magnetic properties, and improving the thermal stability.
The value of c defining the quantity is preferably less than or equal to 0.03.
The value of b + c defining the total amount of M and M 'is preferably in the range of 0.02 to 0.08. If it is less than 0.02, the above effect is small, and if it exceeds 0.08, the Curie temperature becomes too low and is not practical.

Further, the Fe-based soft magnetic alloy ribbon has an alloy composition represented by, for example, the following general formula, and has, for example, about 25% to 95% in terms of area ratio of ultrafine crystals having a grain size of 1000 ° or less. Things.

General formula: Fe _100-defghi D _d E _e G _f Si _g B _h Z _i (II) (wherein, D is at least one element selected from Cu and Au, and E is an element of group IVa. G is at least one element selected from the group consisting of Group Va elements, Group VIa elements and rare earth elements, and G is selected from the group consisting of Mn, Al, Ga, Ge, In, Sn and platinum group elements. Z represents at least one element selected from the group consisting of C, N, and P, and d, e, f, g, h, and i are numbers satisfying the following formulas. However, all numbers in the following formula represent at%.

0.1 ≦ d ≦ 8 0.1 ≦ e ≦ 100 0 ≦ f ≦ 10 12 ≦ g ≦ 25 3 ≦ h ≦ 120 0 ≦ i ≦ 10 15 ≦ g + h + i ≦ 30. Here, D (Cu or Au) in the above formula (II) is an element effective for improving corrosion resistance, preventing coarsening of crystal grains, and improving soft magnetic properties such as iron loss and magnetic permeability. is there. Especially
It is effective for low temperature precipitation of bcc phase. If the amount is too small, the above-described effects cannot be obtained, and if the amount is too large, the magnetic properties deteriorate. Therefore, the content of D is suitably in the range of 0.1 to 8 atomic%. A preferred range is from 0.1 to 5 atomic%.

E (at least one element selected from group IVa, group Va, group VIa, and rare earth elements) is effective in making the crystal grain size uniform, and has magnetostriction and magnetic anisotropy. It is an element that is effective for improving soft magnetic properties and improving magnetic properties against temperature change, and can stabilize the bcc phase in a wider temperature range by adding D (for example, Cu) in combination. If the amount is too small, the above effect cannot be obtained. If the amount is too large, non-crystallinity will not be achieved in the manufacturing process, and the saturation magnetic flux density will be further reduced. Therefore, the content of E is preferably in the range of 0.1 to 10 atomic%. A more preferred range is 1 to 8 atomic%.

The effect of each element in E, together with the above-mentioned effects, is as follows: the group IVa element expands the heat treatment conditions for obtaining the optimum magnetic properties, and the group Va element improves the embrittlement resistance and the workability such as cutting. The group VIa element is effective in improving corrosion resistance and surface properties. In particular, Ta, Nb, W, Mo
Is preferable because V has a remarkable effect of improving soft magnetic properties and V has a remarkable effect of improving surface properties as well as embrittlement resistance.

G (at least one element selected from the group consisting of Mn, Al, Ga, Ge, In, Sn, and platinum group elements) is an element effective for improving soft magnetic properties or corrosion resistance. However, if the amount is too large, the saturation magnetic flux density will decrease.
The following is assumed. In particular, Al is an element effective for refining crystal grains, improving magnetic properties and stabilizing the bcc phase, Ge is effective for stabilizing the bcc phase, and a platinum group element is effective for improving corrosion resistance.

Si and B are elements that assist in non-crystallization of the alloy during production, can improve the crystallization temperature, and are effective elements for heat treatment for improving magnetic properties. In particular, Si forms a solid solution with Fe, which is a main component of fine crystal grains, and contributes to reduction of magnetostriction and magnetic anisotropy. If the amount is less than 12 atomic%, the improvement of soft magnetic properties is not remarkable, and if it exceeds 25 atomic%, the super-quenching effect is small, and relatively coarse crystal grains of μm level are precipitated, and good soft magnetic characteristics are obtained. I can't. Further, Si is an essential element constituting the ordered lattice, and for the appearance of the ordered lattice, 12 to 22 atomic% is particularly preferred. If B is less than 3 atomic%, relatively coarse crystal grains precipitate and good characteristics cannot be obtained, and if it exceeds 12 atomic%, the B compound tends to precipitate due to heat treatment, deteriorating soft magnetic characteristics. Not preferred.

Further, Z (C, N, P) is used as another amorphizing element.
It may be contained in a range of at most atomic%.

The total amount of Si, B and other amorphizing elements is 15
Is preferably in the range of 30 to 30 atomic%, and Si / B ≧ 1 is preferable for obtaining excellent soft magnetic properties.

In particular, by setting the Si content to 13 to 21 atomic%, the magnetostriction λs
0 is obtained, and the magnetic characteristics do not deteriorate due to the resin mold, and the desired excellent soft magnetic characteristics can be effectively exhibited.

The Fe-based soft magnetic alloy may contain trace amounts of unavoidable impurities, such as 0 and S, which are also contained in ordinary Fe-based alloys.

The soft magnetic alloy ribbon used in the present invention has a thickness of 10 mm from the above-mentioned Co-based amorphous alloy ribbon or Fe-based ultrafine crystalline alloy ribbon.
μm or less. The thickness of the soft magnetic alloy ribbon is 10
If it exceeds μm, iron loss in a high frequency range increases, and the response to a high frequency becomes insufficient. More preferably, it is 8 μm or less.

Here, the plate thickness of the soft magnetic alloy ribbon referred to in the present invention is an average plate thickness t, which is obtained by the following equation.

The length at the time of measuring the average thickness is preferably 1 m or more.

The magnetic core of the present invention is formed by winding a very thin soft magnetic alloy ribbon as described above so that the packing factor is in the range of 10% to 65%, and more preferably 15% to 60%. It is configured. The reason for limiting the value of the packing factor to the above range is as follows.

That is, if the packing factor is less than 10%, the total magnetic flux with respect to the magnetic core cross-sectional area becomes too small, and in order to satisfy the required total magnetic flux, the core is increased in size, and as a result, the size is reduced. Will be gone. On the other hand, if the packing factor exceeds 65%, the iron loss as the magnetic core increases, and the low iron loss of the ultrathin soft magnetic alloy ribbon cannot be exhibited.
This is because when the packing factor exceeds 65%, stress is likely to be applied between the wound layers. Particularly, in the case of an ultra-thin ribbon having a thickness of 10 μm or less, the cross-sectional area of the ribbon is small, so the influence of the stress increases. it is conceivable that.

Thus, the value of the packing factor is 10% to 65%
By setting the range, it is possible to sufficiently exhibit the low iron loss of the ultra-thin soft magnetic alloy ribbon, and a magnetic core corresponding to a high frequency with a low loss in a high frequency range, such as a saturable A magnetic core suitable for a reactor, a microminiature inductance element for reducing spike noise, a zero-phase current transformer, and the like can be obtained. Also, by combining a magnetic component using such a magnetic core with other electronic components,
An electronic device such as a switching power supply is obtained.

The magnetic core of the present invention is manufactured, for example, as follows.

First, a soft magnetic alloy ribbon having a thickness of 10 μm or less is manufactured.
When applying a Co-based amorphous alloy ribbon, a ribbon is produced using a single roll method, and when an Fe-based ultrafine crystal alloy ribbon is applied, an amorphous ribbon is produced once. . When producing such an amorphous ultrathin ribbon, it is preferable to adopt the following method in order to obtain a favorable ribbon having few pinholes.

That is, the molten metal is injected into a cooling roll under reduced pressure or in an inert gas atmosphere while satisfying the following conditions, and the molten metal is rapidly cooled. The above manufacturing conditions include the shape of the nozzle for injecting the molten alloy, the distance between the nozzle and the cooling roll, the injection pressure, the material of the cooling roll, the peripheral speed, and the like. The nozzle shape is rectangular and the short side is 0.2 mm or less. The distance between the nozzle and the cooling roll is preferably 0.2 mm or less, and the pressure during injection is 0.03 kg /
cm ² or less is preferred. The material of the cooling roll is Cu-based alloy or Fe
Preferably, the base alloy has a peripheral speed of 20 m / sec or more. Also,
The atmosphere for injecting the molten alloy is preferably under a reduced pressure of 10 ⁻² Torr or less or under an inert atmosphere of 60 Torr or less.

After producing a good ribbon with few pinholes in this way, when a Co-based amorphous alloy is applied,
After being wound within a predetermined packing factor, heat treatment is performed in a temperature range of not higher than the crystallization temperature and not lower than the Curie temperature, and the resultant is cooled to obtain a magnetic core corresponding to a desired high frequency.

When an Fe-based ultrafine crystal alloy is applied, after winding an amorphous ribbon within a predetermined packing factor, at an appropriate temperature equal to or higher than the crystallization temperature of the amorphous alloy, 30 minutes to 15 minutes Heat treatment for 10
Ultra-fine crystal grains of 00 ° or less are precipitated, and a magnetic core corresponding to a desired high frequency is obtained. The fine crystal grains having a grain size of 1000 mm or less in the Fe-based ultrafine crystal alloy ribbon have an area ratio of 25% or less.
It is preferred to be present in the range of ~ 95%. If the area ratio of fine crystal grains is too small, that is, if the amorphous phase is too large, iron loss is large, magnetic permeability is low, and magnetostriction is large. On the other hand, if the amount is too large, the magnetic properties deteriorate. A more preferable abundance ratio of the fine crystal grains in the alloy is in a range of 40 to 90% in terms of an area ratio. In this range, soft magnetic characteristics can be obtained particularly stably.

Further, as a heat treatment, heat treatment in a non-magnetic field or in a magnetic field (a thin film axial direction, a width direction, a thickness direction, a rotating magnetic field heat treatment) may be added.

When winding the soft magnetic alloy ribbon, it is preferable to form an insulating layer on at least one surface of the ribbon in advance.

Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 [(Co _0.94 Fe _0.06 ) _0.95 Mo _0.05 ] An alloy composition represented by ₇₄ (Si _0.5 B _0.5 ) ₂₆ was prepared and melted to obtain a master alloy for producing an amorphous alloy. An amorphous alloy ribbon was produced by a roll method.

The nozzle shape when injecting molten metal has a slit shape of 5 mm x 0.15 mm, and the distance between the nozzle and the cooling roll is 0.1 mm
And The material of the cooling roll was Fe. Such a single roll device is placed in a vacuum chamber, and the inside of the vacuum chamber is preliminarily evacuated to 5 × 10 ⁻⁵ Torr, then He gas is sealed to 30 Torr, and a cooling roll controlled at a peripheral speed of 57 m / sec. A molten metal was injected at a pressure of 0.02 kg / cm ² onto the peripheral surface of, and was rapidly quenched to obtain a long Co-based amorphous alloy ribbon having a thickness of 5.2 μm and a width of 4.8 mm. In addition, the obtained ribbon was excellent in surface property and few with pinholes.

Next, the long ultra-thin Co-based amorphous ribbon was wound into a toroidal shape having an outer diameter of 15 mm and an inner diameter of 10 mm with various packing factors, and these wound bodies were subjected to a strain relief heat treatment at 440 ° C. for 40 minutes. After the application, the cores were cooled at a rate of 2 ° C./min to obtain respective magnetic cores.

As the high-frequency magnetic characteristics of each magnetic core thus obtained, the iron loss at 2 MHz was measured using a magnetic characteristic evaluation device SY-8617 (trade name, manufactured by Iwatsu Co., Ltd.). The total magnetic flux was also measured. These results are shown in FIG.

As is clear from the figure, all the magnetic cores within the packing factor value of the present invention show a low iron loss value, and when the packing factor exceeds 65%, the iron loss value increases rapidly. I understand. Note that the total magnetic flux decreases with the packing factor, and it can be seen that if the total magnetic flux is less than 10%, it is not practical.

Example 2 Using the alloy compositions shown in Table 1 as starting materials, Co-based amorphous alloy ribbons were produced under the same production conditions as in Example 1, and a magnetic core having a packing factor shown in Table 1 was prepared. It was produced in the same manner as in Example 1. The heat treatment after the winding was performed under the optimum conditions for each amorphous alloy.

The iron loss of each magnetic core was measured in the same manner as in Example 1.
The results are shown in Table 1.

As is clear from the results in Table 1, it is found that all the magnetic cores having the packing factor in the range of the present invention can obtain low iron loss.

Example 4 An alloy composition represented by Fe ₇₂ Cu ₁ V ₆ Si ₁₃ B ₈ was prepared and melted to obtain a mother alloy for producing an Fe-based ultrafine crystal alloy. First, a single roll method under the following conditions was used. An amorphous ribbon was produced.

The nozzle shape during injection of the molten metal was a slit shape of 5.2 mm x 0.15 mm, and the distance between the nozzle and the cooling roll was 0.15
mm. The material of the cooling roll was a Cu alloy.
Such a single roll device is placed in a vacuum chamber, and the inside of the vacuum chamber is evacuated to 5 × 10 ⁻⁵ Torr, and then the peripheral speed is reduced.
0.025 kg pressure on the peripheral surface of the cooling roll controlled at 42 m / sec
Inject molten metal at / cm ² , super-cooled, plate thickness 7.8 μm, width 5
A long amorphous ribbon of mm was obtained. In addition, the obtained ribbon was excellent in surface property and few with pinholes.

Next, the long ultra-thin amorphous ribbon was wound into a toroidal shape having an outer diameter of 12 mm and an inner diameter of 8 mm with various packing factors, and these wound bodies were finely ground at 570 ° C. for 2 hours in an N ₂ atmosphere. Heat treatment for crystal precipitation was performed to obtain magnetic cores.

The core loss at 2 MHz of each magnetic core thus obtained was measured in the same manner as in Example 1. FIG. 2 shows the results together with the total magnetic flux.

As is clear from the figure, even when the Fe-based ultrafine crystalline alloy ribbon was used, a low iron loss was obtained within the packing factor value of the present invention, similarly to the Co-based amorphous alloy ribbon. You.

Example 4 Using the alloy compositions shown in Table 2 as starting materials, amorphous ribbons were produced under the same production conditions as in Example 3, and magnetic cores having the packing factors shown in Table 2 were produced. It was produced in the same manner as in Example 1. The heat treatment for the precipitation of fine crystals after winding was performed under the optimum conditions for each alloy.

The iron loss of each magnetic core was measured in the same manner as in Example 1.
The results are shown in Table 2.

As is clear from the results in Table 2, it is found that all the magnetic cores having the packing factor within the range of the present invention can obtain low iron loss.

[Effects of the Invention] As described above, according to the present invention, a soft magnetic alloy ribbon having a thickness of 10 µm or less is used, and the packing factor is 10% to
The magnetic core in the range of 65% can sufficiently exhibit soft magnetic properties in a high-frequency region of an ultrathin soft magnetic alloy ribbon, for example, low iron loss. As a result, for example, excellent soft magnetic characteristics are required at high frequencies used for noise filters, saturable reactors, ultra-small inductance elements for reducing spike noise, transformers, various choke coils, zero-phase current transformers, magnetic heads, and the like. In addition, it is possible to provide a downsized magnetic core at a practical level.

[Brief description of the drawings]

FIG. 1 is a graph showing the iron loss and total magnetic flux of a magnetic core using a Co-based amorphous alloy ribbon according to one embodiment of the present invention in comparison with a conventional example, and FIG. 2 is another embodiment of the present invention. 4 is a graph showing the iron loss and total magnetic flux of a magnetic core using a Fe-based ultrafine crystal alloy ribbon in comparison with a conventional example.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-228601 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01F 3/00-3/04 H01F 27 / 24-27 / 25,41 / 02

Claims (1)

(57) [Claims] 1. A magnetic core comprising a winding of a soft magnetic alloy ribbon having a thickness of 10 μm or less, wherein a packing factor of the winding is in a range of 10% to 65%. core.