JP2692089B2 - Powder compact magnetic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder compact magnetic body (for example, a dust core). B. 2. Description of the Related Art In a high frequency circuit, a large number of inductors are used for various purposes, and these are combined with a capacitor to form a resonance circuit, a filter, a matching circuit, or the like. A high-frequency circuit in which these resonance inductors are used has a high frequency to handle and has a very small voltage or current. Therefore, it is particularly required that the loss of the circuit itself is small. Therefore, all components such as inductors used in the circuit must be of good quality with less loss in the high frequency range. Further, the inductor is required to have a high quality factor (called Q factor). The Q value represents the sharpness of resonance, is a ratio of reactance and resistance, and is a value given by the following equation (1). Q = ωL / R = 2πfL / (Reff−Rw) (1) where ω is the resonance angular frequency, R is the resistance, f is the measurement frequency, L is the inductance of the coil, Reff is the effective resistance of the coil, and Rw is the winding. It is the DC resistance of the wire. Further, the total loss including iron loss is given by the following equation (2). Total loss = 1 / μQ (2) where μ is magnetic permeability. Further, in a circuit used for a resonance circuit or a filter, it is important that the inductance has a constant value and does not fluctuate so that the frequency characteristic does not change. This is strictly required for an LC oscillator and the like. In such a high frequency circuit, a powder core of carbonyl iron has been conventionally used, but the magnetic permeability of this powder core that is normally used is around 10 or less. Conventionally used magnetic cores of inductance elements are those using sendust in the low frequency range and low permeability and high Q value using carbonyl iron in the high frequency range. However, carbonyl iron used in the high frequency range has a large loss because it has a low magnetic permeability even if the Q value is high, as can be seen from the equation (2). Carbonyl iron can be made to have a high magnetic permeability by changing the molding conditions, but the Q value becomes low when the magnetic permeability is increased. Sendust has a high magnetic permeability, but has a low Q value in a high frequency range. The above magnetic properties of carbonyl iron and sendust at high frequencies are summarized in the table below. In addition, farite has a low saturation magnetic flux density of about 3000 to 5000 G and is not satisfactory as a magnetic core. C. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a powder compact magnetic body having a high magnetic permeability and a high Q value in a high frequency range. D. The present invention is a powder compact magnetic material for use in a high frequency circuit, wherein the magnetic material is compacted with a soft magnetic amorphous alloy powder of substantially 44 μm or less. The crystalline alloy
Co _50-80 Fe _2-7.5 Ni _0-18 Si _7-20 B _5-20 ; Fe _40-88 (Co, Ni)
_0-40 (P, B, C, Si) _12-25 or Ni _40-84 (Co, Fe) _4-40 (P,
B, C, Si) _12-25 related to the powder compact magnetic material. E. Examples Hereinafter, examples of the present invention will be described. Amorphous alloys have attracted attention as various functional materials because of their unique chemical and mechanical properties that are not found in ordinary crystalline alloys. Among them, amorphous alloys such as iron-based and cobalt-based do not exhibit crystal anisotropy, and therefore have extremely small coercive force and high magnetic permeability, and thus exhibit extremely good soft magnetic properties. Therefore, the powder magnetic core using the powder of such an amorphous alloy can obtain excellent magnetic characteristics which are not found in the conventional powder magnetic cores. Amorphous alloy pieces can be cut from ribbons or
Although it can be produced by the extraction method, from the viewpoint of productivity, the cavitation method (having a surface layer having a small wettability with respect to the molten metal) that the applicant previously proposed in JP-A-58-6907 was used. , Supplying molten metal to the surface of the roll rotating at high speed, dividing this molten molten metal into fine molten metal droplets, and subsequently colliding this molten metal droplet with a metal rotating body rotating at high speed. A method of rapid solidification.)
It is desirable to apply. Hereinafter, specific examples of the present invention will be described. Co _68.8 Fe _4.2 Si _17.5 by the cavitation method
B _9.5 (The number attached to the element symbol is the atomic% of the element
Represents same as below. ) Was produced. The magnetostriction of this amorphous alloy powder is zero, the saturation magnetic flux density is 7000G,
The magnetic permeability is 10000. The particle diameter of the powder particles can be 10 μm or less (average 5 μm), 10 to 44 μm, 44 to 74 μm, 74 to 149 μ by selecting the peripheral speed of the metal rotating body.
m and 149 to 297 μm. With respect to these amorphous alloy powders, the electron binding energy of Co2P orbitals was measured by X-ray electron spectrum analysis (ESCA) with C1S as a standard. In the measurement, both the particles whose surface was cleaned by argon etching for 6 minutes in the measuring device and the particles which were not subjected to the above treatment were measured. The measurement results are shown in FIGS. 2 (a) and 2 (b).
Figure (a) is Figure (b) The measurement results are shown respectively. When the particle size of the powder particles is coarse to 44 to 74 μm or more, a large difference in electron binding energy is recognized depending on the presence or absence of the argon etching treatment, but when the particle size is 44 μm or less, the difference between the two becomes small. Co electron binding energy is Is 793.0 eV, Is said to be 777.9 eV, and the electron binding energy of CoO is Is 795.5 eV, Is 780.0 eV, and lines showing these values are drawn in the figure. If the particle size is 44 to 74 μm or more, the electron binding energy is The value of electron binding energy is higher than the value of Less than the value of. On the other hand, when the particle size is 44 μm or less, the difference in the electron binding energy due to the presence or absence of the argon etching treatment is small, and in the sample whose surface is cleaned by the argon etching treatment, the electron binding energy is Or Approaching the value of and the particle size becomes 10 μm or less, The value is extremely close to the value of. From the above results, when the particle size is 44 μm or less (particularly 10 μm or less), the oxide film on the particle surface is thickly formed, and the oxide film is surely adhered to the particle surface even if the surface cleaning treatment by argon etching is performed. You can understand what you are doing. Therefore, in the case of a fine powder having a particle size of 44 μm or less (particularly 10 μm or less), an oxide film is surely formed on the surface of the particle and a sufficient insulating property can be expected without any special treatment. As a result, there is little eddy current loss, and therefore a high-quality powder magnetic core having a high Q value can be obtained. Next, the magnetic characteristics of the dust core will be described. The above-mentioned five kinds of amorphous alloy powders were compression-molded with a thermoplastic resin as a binder at a molding pressure of 5 t / cm ² , and the temperature was 150 ° C.
It was fired in a powder magnetic core. For each of these dust cores, the frequency was changed and the initial permeability μ ₀ and the Q value were measured. The result is as shown in FIG. The smaller the grain size of the alloy powder, the lower the magnetic permeability, but the frequency exhibiting a high Q value shifts to the high frequency side. From the above results, it can be understood that a powder magnetic core having a powder particle size of 44 μm or less, particularly 10 μm or less can obtain a high Q value even in a high frequency range. Also, in FIG. 1, for comparison, carbonyl iron powder having a particle size of 10 μm or less (average of about 7 μm) was subjected to heat treatment at 500 ° C. for 2 hours, and an oxide film (insulating film) was formed on the powder particle surface.
And the result of the same measurement of the powder magnetic core formed by compression molding using water glass as a binder. As can be seen from FIG. 1, a dust core made of soft magnetic amorphous alloy powder having a particle size of 44 μm or less is
The magnetic permeability is higher than that of the conventional powder magnetic core for comparison, and a high Q value is obtained up to the high frequency side. The result is that the magnetic permeability of the individual particles of the soft magnetic amorphous alloy powder is high, and because the frequency characteristics are superior to the carbonyl iron powder, the powder magnetic core using the powder having substantially the same particle diameter, This is because the magnetic core as a whole is provided with a function superior to that of the conventional product. As described above, the dust core according to the above example has a magnetic permeability,
Both of the high Q values in the high frequency range are ideal for high frequency circuits, and it is possible to realize a circuit element that has not been realized in the past, that maintains high inductance in the high frequency range. Moreover, by using a fine powder, it is not necessary to perform a treatment for insulation between powder particles, which is convenient from the viewpoint of productivity. It is also possible to reduce the size of each element in the circuit. The composition of the amorphous alloy powder is not limited to the above example, and any one of cobalt-based, iron-based, and nickel-based amorphous alloy powders exhibiting soft magnetism can be used.
For example, in cobalt-based alloys, Co _50-80 Fe _2-7.5 Ni
_{0 to 18} Si _{7 to 20} B ₅ to ₂₀ are Fe _{40 to 88} (C
_{o, Ni) 0~40 (P,} B, C, Si) 12~25 is a nickel-based alloy _{Ni 40~84 (Co, Fe) 4~40} (P, B, C, S
i) ₁₂ to ₂₅ can be used similarly. F. EFFECTS OF THE INVENTION As described above, the powder compact magnetic material according to the present invention uses the soft magnetic amorphous alloy powder, and thus has high magnetic permeability, and further, the particle diameter of the powder is substantially 44 μm. Since it is set as follows, it shows a high Q value in a high frequency range. As a result, it becomes possible to realize a circuit element that has not been realized in the past, that maintains a high inductance in a high frequency region, and a high quality high frequency circuit with less loss can be obtained by using it in various elements of a high frequency circuit. Further, it is possible to reduce the size of these elements. Further, by setting the particle size of the powder particles to substantially 44 μm or less, an oxide layer is surely formed on the surface of the particles, and a treatment for insulation between particles is unnecessary, which is advantageous from the viewpoint of productivity. .

BRIEF DESCRIPTION OF THE DRAWINGS The drawings each show an embodiment of the present invention, and FIG. 1 shows the change in permeability and the Q value of the soft magnetic amorphous alloy powder of a dust core depending on the particle diameter. FIGS. 2 (a) and 2 (b) are graphs showing changes in frequency dependence, and FIGS. 2 (a) and 2 (b) are graphs showing changes in electron binding energy depending on the particle diameter of the soft magnetic amorphous alloy powder, respectively.

Claims (1)

(57) [Claims] A compacted magnetic body for use in a high frequency circuit, wherein the magnetic body is compacted with a soft magnetic amorphous alloy powder having a particle size of substantially 44 μm or less, and the soft magnetic amorphous alloy is Co _{50 -80} F
e _2-7.5 Ni _0-18 Si _7-20 B _5-20 ; Fe _40-88 (Co, Ni) _0-40 (P,
B, C, Si) _12-25 or Ni _40-84 (Co, Fe) _4-40 (P, B, C, Si)
Powder compact magnetic material selected from _12-25 .