JP2698769B2 - Manufacturing method of high permeability core - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic filter having a high magnetic permeability such as a noise filter, a saturable reactor, an ultra-small inductance element for reducing spike noise, and a zero-phase current transformer magnetic head. The present invention relates to a method for manufacturing a high-permeability magnetic core suitable for a required use. 2. Description of the Related Art With the advancement of the performance of electronic devices, the performance of magnetic components used as important functional parts also needs to be improved. Therefore, excellent magnetic properties are also required for the magnetic materials used for these magnetic components. Particularly, for many magnetic components such as current sensors such as zero-phase current transformers and noise filters, materials having high magnetic permeability are required. Is valid. [0003] A noise filter will be described as an example. A switching power supply is widely used as a stabilized power supply for computer peripherals and general communication equipment. In a switching power supply, when a power supply voltage is input to a device from a power supply line, a noise voltage other than a predetermined power supply voltage may enter the device and be input. Also, high frequency noise having a switching frequency as a fundamental frequency, or MH generated from a load, for example, a logic circuit of a personal computer.
The noise in the z region becomes a problem. In order to reduce these conduction noises, for example, a common mode choke coil as shown in FIG. 4 is used as a noise filter. In FIG. 4, a choke coil 1 is obtained by applying a pair of windings 3a and 3b to a magnetic core 2 so that magnetic flux due to a reciprocating current is canceled.
Capacitors 4a, 4b, 4c are connected between them, and capacitors 4b, 4c
Connection point is grounded. When this filter is inserted in the power supply line, the magnitude of the noise output voltage with respect to the noise input voltage is related to the magnetic permeability of the magnetic core, and the noise output voltage decreases as the magnetic permeability increases. Further, it is necessary to function effectively not only in the low-frequency region but also in the high-frequency region of 1 MHz or more, and therefore, it is necessary that the frequency characteristics of the magnetic permeability be good. Hitherto, ferrite has been used as a material constituting the magnetic core of the common mode choke coil. However, recently, relatively low frequency range (10 to 450)
KHZ) noise regulations are becoming stricter,
Ferrite has a drawback that noise cannot be sufficiently reduced because of low magnetic permeability in a low frequency range. Therefore, there has been a demand for a magnetic core having a large magnetic permeability particularly in a low frequency region and excellent in frequency characteristics. [0007] On the other hand, amorphous alloys that have recently attracted attention generally have high magnetic permeability. Therefore, studies have been made to use the amorphous alloys as cores of common mode choke coils. However, there are many things that are not always enough to reduce the noise level, and a compositional approach to a high-permeability amorphous alloy may approach its limit in the future. [0008] As described above, a magnetic core for a noise filter is first required to have high magnetic permeability, and is further required to have high magnetic permeability in a wider frequency band. In particular, having high magnetic permeability is advantageous in applications mainly using magnetic permeability, and contributes to downsizing, high precision, and high sensitivity of equipment. An object of the present invention is to provide a method for manufacturing a high-permeability magnetic core capable of obtaining a magnetic core having a high magnetic permeability. According to the present invention, the Curie temperature (Tc) satisfies the relationship of 120 ° C. ≦ Tc ≦ 253 ° C. and the saturation magnetostriction constant (λs) is −2 × 10 ⁻⁶ ≦ λ
A magnetic field is applied in the width direction of the ribbon to a core made of a ribbon of a Co-based amorphous alloy having a range of s ≦ 1 × 10 ⁻⁶ , and heat treatment is performed at a Curie temperature or lower. This is a method for producing a high permeability magnetic core. The present inventors have studied various aspects such as composition and heat treatment in order to achieve high magnetic permeability. as a result,
A Co-based metal having a Curie temperature of 120 to 253 ° C, more preferably 150 to 253 ° C, furthermore 200 to 253 ° C, and more preferably 220 to 250 ° C, and a saturation magnetostriction constant of −2 × 10 ⁻⁶ to 1 × 10 ^−6. It has been found that a high magnetic permeability can be obtained specifically by performing a heat treatment at a temperature not higher than the Curie temperature while applying a magnetic field in the width direction of the ribbon to the magnetic core made of the amorphous alloy. The amorphous alloy to be used is a Co-based amorphous alloy containing Si, B, P, C, etc. as metalloid, and has a near zero magnetostriction. Zr, Hf, Ta, Nb
It may be a metal / metal-based amorphous alloy having an amorphous element as an element. In particular, it is preferable to use one containing Si and B. By containing a small amount of Fe, a material near zero magnetostriction can be obtained. The magnitude of the magnetostriction is also important in the present invention, and particularly high magnetic permeability can be obtained in the range of the saturation magnetostriction constant λs = −2 × 10 ⁻⁶ to 1 × 10 ⁻⁶ . Preferred amorphous alloy compositions include the following. (Co _1-a Fe _a ) _100-z (Si _{1- y By} ) _z 0.02 ≦ a ≦ 0.08 25 ≦ z ≦ 32 0.3 ≦ y ≦ 0.5 Is necessary to obtain near zero magnetostriction. By setting the value of a between 0.02 and 0.08, preferably 0.03 and 0.07 according to z and y, An alloy can be obtained. The most important thing in this amorphous alloy is the metalloid element S
It is a compounding ratio of i and B. That is, B is an essential component for making the alloy amorphous, and the addition of Si facilitates the amorphous formation and improves the thermal stability. In particular, in order to obtain a magnetic core having a high magnetic permeability. It is desired that the value of y, which indicates the compounding ratio of Si and B, be specified in the range of 0.3 to 0.5 to make the composition rich in Si. This means that y is less than 0.3 or 0.
If it exceeds 5, the magnetic permeability tends to decrease,
Further, the thermal stability of the magnetic properties is also slightly deteriorated. In addition, it is difficult to obtain a high magnetic permeability even if the treatment according to the present invention is performed. The reason why the range of z indicating the blended amount of Si and B is set to 25 to 32 is that if z is less than 25, the effect of improving the magnetic permeability according to the present invention, particularly high magnetic permeability cannot be obtained in a low frequency range. On the other hand, when the temperature exceeds 32, the Curie temperature is lowered, which is not practical, and the treatment of the present invention is not effective. The amorphous alloy has Ti, V, Cr, Mn, and N in order to improve corrosion resistance, thermal stability, and the like.
i, Cu, Zr, Nb, Mo, Hf, Ta, W and the platinum group may be added in such a manner as to replace Co. These elements can be added until the Curie temperature of the amorphous alloy reaches the lower limit of a practical temperature, and this value can be up to about 8 atomic%, but is practically about 4 atomic% or less. The following is shown together with the above alloy. (Co _1-ab Fe _a M _b ) _100-z (Si _{1- y By} ) _{z where} M: Ti, V, Cr, Mn, Ni, Cu, Z
at least one of r, Nb, Mo, Hf, Ta, W, and platinum group 0.02 ≦ a ≦ 0.080 0 ≦ b ≦ 0.08 0.3 ≦ y ≦ 0.5 25 ≦ z ≦ 32 and M component When Mn is selected as Mn, Mn is 6 atm.
% Or more, Fe may be unnecessary. Further, the amorphous alloy used in the present invention is:
An alloy material having a predetermined composition ratio can be easily manufactured from a molten state by a conventional method such as a liquid quenching method in which the alloy material is rapidly cooled at a cooling rate of 10 ⁵ ° C / sec or more. This amorphous alloy is used, for example, as a plate-shaped ribbon manufactured by a single roll method. In this case, it is difficult to manufacture a ribbon having a thickness of less than 5 μm, and if the thickness exceeds 25 μm, the magnetic permeability in a high-frequency range decreases rapidly.
It is preferable to set it in the range of 25 μm. The ribbon of the amorphous alloy obtained as described above is wound or laminated, formed into a magnetic core shape, subjected to heat treatment for strain relief, and then cooled. 5-
It is desirable to be 50 ° C./min. This is because if the cooling rate is less than 0.5 ° C./min or exceeds 50 ° C./min, the magnetic permeability decreases. A more preferable range of the cooling rate is 1 to 20 ° C./min. Subsequently, a heat treatment in a magnetic field is performed. In the heat treatment in a magnetic field according to the present invention, a magnetic field is applied in the width direction of the ribbon constituting the magnetic core. This is shown in FIG. As shown in the figure, the magnetic field is applied in the width direction (2) of the magnetic core (1) around which the amorphous alloy ribbon is wound, but if the magnetic field is effectively applied in this direction, the width direction ( Some inclination from 2) is acceptable. The heat treatment in a magnetic field may be performed continuously to the above-described heat treatment for removing strain, or may be once cooled and then heated again. The magnetic field may be applied for the first time during the heat treatment in the magnetic field, or may be applied during the strain relief heat treatment. The heat treatment temperature may be lower than the Curie temperature, but practically 100 ° C. or higher. Preferably 130
It is more effective that the temperature is equal to or higher than 180 ° C. The atmosphere is not particularly limited, and may be any of an inert gas such as N ₂ and Ar, a vacuum, a reducing atmosphere such as H _{2, and the} like. The heat treatment time is preferably 10 minutes or more. It is not particularly necessary to maintain the same temperature, but it is sufficient to maintain the temperature in a temperature range of about 100 ° C. or more for about 10 minutes to 3 hours.
Although the cooling rate after the heat treatment is not particularly specified, it is 0.1 d
eg / min. It may be about 100 deg / min. The intensity of the applied magnetic field is 1 Oe or more, preferably 10 Oe.
e or more. Embodiments of the present invention will be described below. Example 1 A Co-based amorphous alloy (−2 × 10 ⁻⁶ ≦ λs ≦ 1 × 10 ⁻ ) using Co—Fe · Si—B as a constituent element and changing the composition ratio to change the Curie temperature (Tc). ⁶ ) was wound to form a magnetic core. The width of the amorphous alloy ribbon was 5 mm and the thickness of the plate was 18 μm.
The magnetic core shape has an outer diameter of 20 mm and an inner diameter of 14 mm. After these cores are heat-treated to remove strain, 200
While applying the magnetic field of Oe in the width direction of the ribbon, (Tc-2
A heat treatment was performed at a temperature of 0) ° C. for 60 minutes. Then 3
It cooled at the rate of ° C / min. FIG. 2 shows that f = 10 k in a magnetic field of 2 mOe.
Hz shows the magnetic permeability (μ'10 kHz). As is clear from the figure, the magnetic permeability is remarkably improved at Tc = 120 to 253 ° C. Example-2 Co-based amorphous alloys shown in Tables 1 and 2 (-2 × 10 ⁻⁶ ≦
A magnetic core was fabricated in the same manner as in Example 1 using λs ≦ 1 × 10 ⁻⁶ ), and after the heat treatment for strain relief, heat treatment in a magnetic field in the direction of the ribbon width under the optimum condition at Tc or less was performed. 2mOe, 10kHz
Are also shown. As is clear from the table, it can be seen that the magnetic permeability is very high in the present invention. In particular, the sample No. 1-3 and 6-19 are Si
However, it can be seen that the magnetic permeability is very large. [Table 1] [Table 2] Example 3 A magnetic core was prepared in the same manner as in Example 1 using a Co-based amorphous alloy shown in Table 3, and after the strain relief heat treatment, was performed at Tc or less for 30 minutes and 50 minutes.
Oe was subjected to a heat treatment in a magnetic field in the ribbon width direction. Note that the saturation magnetostriction constant (λs) in the table was measured using a strain gauge. When the measurement sensitivity was smaller than that, the sign was obtained from a change in the hysteresis curve by applying a stress to the ribbon. The magnetic permeability at 10 kHz (measured magnetic field: 2 mOe) is shown in the table. As is clear from this table, λs = −2 × 1
In a Co-based amorphous alloy having 0 ^-6 to 1 × 10 ^-6 , the effect of the heat treatment in the magnetic field in the width direction is large, and the value is very high. [Table 3] Example-4 The same heat treatment in a magnetic field as in Example-1 was performed (Co _0.94 F
e _0.06 ) A common mode choke coil was prepared using an amorphous alloy core of ₇₁ Si ₁₇ B ₁₂ (Tc = 230 ° C., λs = 0), and was incorporated in a switching power supply to measure a noise reduction effect. The switching frequency is 40 kHz, and the noise is 40 kHz and its harmonics of 80 kHz, 12 kHz.
The reduction effect at 0 kHz was measured. For comparison _{(Co 0. 94 Fe 0.06) 71} Si 5 B 24 (Tc = 340
° C) subjected to the same treatment as in Example-1 (Comparative Example-
1), those using ferrite (Comparative Example-2), and C
Example 1 on o ₇₀ Fe ₄ Si ₁₇ B ₉ (Tc = 268 ° C.)
Measurements were also performed on a sample subjected to the same processing as in (Comparative Example-3), and the results are shown in Table 4. [Table 4] As is clear from Table 4, the present invention has an excellent noise reduction effect. Example-5 FIG. 3 shows aging characteristics when the initial value of the effective magnetic permeability at 10 kHz is 1.0 when the magnetic core of Example-4 and the magnetic core of Comparative Example-1 are aged at 120 ° C. FIG. 3 clearly shows that the present invention is superior in aging characteristics. Further, it was confirmed that the time-dependent change of the noise level when a common mode choke was prepared and incorporated in the switching power supply was the same as in FIG. 3, and the noise level hardly changed in the noise filter using the present invention. Was. In Example 4, μ10 kHz before the heat treatment in the magnetic field is about 6.5 × 10 ⁴ , and 1.31 × 10 ⁵ after the heat treatment in the magnetic field. Therefore, it can be seen that high magnetic permeability is maintained even after long-term aging. As described above, according to the present invention, a magnetic core having excellent magnetic permeability can be obtained. Therefore, it is suitable for various magnetic cores such as a noise filter, a semiconductor circuit reactor, and a saturable reactor that exclusively use magnetic permeability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing heat treatment in a magnetic field. FIG. 2 is a graph showing magnetic permeability-Curie temperature characteristics of a Co-based amorphous alloy ribbon. FIG. 3 is an aging characteristic diagram of an amorphous alloy core. FIG. 4 is a circuit diagram showing a common mode choke coil.

Claims (1)

(57) [Claims] Curie temperature (Tc) is 120 ° C ≦ Tc ≦ 253 ° C
And the saturation magnetostriction constant (λs) is −2 × 1
A magnetic field is applied in the width direction of the ribbon to a core made of a Co-based amorphous alloy in the range of 0 ⁻⁶ ≦ λs ≦ 1 × 10 ⁻⁶ , and a heat treatment at a Curie temperature or lower is performed. A method for manufacturing a high-permeability magnetic core. 2. The method according to claim 1, wherein 220 ° C. ≦ Tc ≦ 250 ° C. 3. 2. The method according to claim 1, wherein the magnetic field is at least 10 Oe. 4. 2. The method according to claim 1, wherein the magnetic field is 10 Oe or more. 5. Co-based amorphous alloy is (Co _1-ab Fe _a M _b ) _100-z (Si _{1- y By} ) _{z where} M: Ti, V, Cr, Mn, Ni, Cu, Zr,
At least one of Nb, Mo, Hf, Ta, W and the platinum group is represented by 0.02 ≦ a ≦ 0.080 0 ≦ b ≦ 0.04 0.3 ≦ y ≦ 0.5 25 ≦ z ≦ 32 The method for producing a high-permeability magnetic core according to claim 1. 6. The Co-based amorphous alloy is (Co _1-a Fe _a ) _100-z (Si _{1- y By} ) _z 0.02 ≦ a ≦ 0.08 0.3 ≦ y ≦ 0.5 25 ≦ z ≦ 32 The method for manufacturing a high-permeability magnetic core according to claim 1, wherein: 7. 2. The method according to claim 1, wherein the thickness of the ribbon is 5 to 25 [mu] m.