U.S. patent application number 11/125747 was filed with the patent office on 2005-11-17 for high-frequency core and inductance component using the same.
This patent application is currently assigned to NEC TOKIN CORPORATION. Invention is credited to Fujiwara, Teruhiko, Inoue, Akihisa, Urata, Akiri.
Application Number | 20050254989 11/125747 |
Document ID | / |
Family ID | 34936273 |
Filed Date | 2005-11-17 |
United States Patent
Application |
20050254989 |
Kind Code |
A1 |
Fujiwara, Teruhiko ; et
al. |
November 17, 2005 |
High-frequency core and inductance component using the same
Abstract
A high-frequency core is a molded body obtained by molding a
mixture of a soft magnetic metallic glass powder and a binder in an
amount of 10% or less in mass ratio. The powder has an alloy
composition represented by
(Fe.sub.1-aCo.sub.a).sub.100-x-y-z-q-r(M.sub.1-pM'.sub.p).sub.xT.sub.yB.s-
ub.zC.sub.qAl.sub.r(0<a<0.50, 0<p<0.5, 2 atomic
%<x<5 atomic %, 8 atomic %<y<12 atomic %, 12 atomic
%<z<17 atomic %, 0.1 atomic %<q<1.0 atomic %, 0.2
atomic %<r<2.0 atomic % and 25<(x+y+z+q+r)<30, M being
at least one selected from Zr, Nb, Ta, Hf, Mo, Ti, V, Cr, and W, M'
being at least one selected from Zn, Sn, and R (R being at least
one element selected from rare earth metals including Y), T being
at least one selected from Si and P). An inductance component is
formed by the core and a winding.
Inventors: |
Fujiwara, Teruhiko;
(Sendai-shi, JP) ; Urata, Akiri; (Sendai-shi,
JP) ; Inoue, Akihisa; (Sendai-shi, JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN & CHICK, PC
220 5TH AVE FL 16
NEW YORK
NY
10001-7708
US
|
Assignee: |
NEC TOKIN CORPORATION
Sendai-shi
JP
TOHOKU UNIVERSITY
Sendai-shi
JP
|
Family ID: |
34936273 |
Appl. No.: |
11/125747 |
Filed: |
May 9, 2005 |
Current U.S.
Class: |
420/8 ;
420/40 |
Current CPC
Class: |
H01F 1/15325 20130101;
H01F 1/15375 20130101; H01F 41/0246 20130101; H01F 3/14 20130101;
H01F 17/062 20130101; H01F 1/15308 20130101; H01F 1/15316 20130101;
H01F 2017/048 20130101 |
Class at
Publication: |
420/008 ;
420/040 |
International
Class: |
C22C 038/18 |
Foreign Application Data
Date |
Code |
Application Number |
May 17, 2004 |
JP |
2004-146595 |
Claims
1. A high-frequency core comprising a molded body obtained by
molding a mixture of a soft magnetic metallic glass powder and a
binder in an amount of 10% or less in mass ratio with respect to
the soft magnetic metallic glass powder, said soft magnetic
metallic glass powder having an alloy composition represented by
(Fe.sub.1-aCo.sub.a).sub.100-x-y-z-q-r(M-
.sub.1-M'.sub.p).sub.xT.sub.yB.sub.zC.sub.qAl.sub.r, where
0<a<0.50, 0<p<0.5, 2 atomic %<x<5 atomic %, 8
atomic %<y<12 atomic %, 12 atomic %<z<17 atomic %, 0.1
atomic %<q<1.0 atomic %, 0.2 atomic %<r<2.0 atomic %
and 25<(x+y+z+q+r)<30, M being at least one element selected
from the group consisting of Zr, Nb, Ta, Hf, Mo, Ti, V, Cr and W,
M' being at least one element selected from the group consisting of
Zn, Sn and R, R being at least one rare earth metal element
selected from the group consisting of a lanthanum series element
and Y, T being at least one element selected from the group
consisting of Si and P.
2. The high frequency core according to claim 1, wherein the molded
body has a powder filling rate of 50% or more, a magnetic flux
density of 0.5 tesla or more when a magnetic field of
1.6.times.10.sup.4 A/m is applied, and a specific resistance of
1.times.10.sup.4 .OMEGA.cm or more.
3. The high-frequency core according to claim 1, wherein the molded
body is obtained by preparing the mixture of the soft magnetic
metallic glass powder and the binder in an amount of 5% or less in
mass ratio with respect to the soft magnetic metallic glass powder,
and compression-molding the mixture using a die, the molded body
having a powder filling rate of 70% or more, a magnetic flux
density of 0.70 tesla or more when a magnetic field of
1.6.times.10.sup.4 A/m is applied, and a specific resistance of 1
.OMEGA.cm or more.
4. The high frequency core according to claim 1, wherein the molded
body is obtained by preparing the mixture of the soft magnetic
metallic glass powder and the binder in an amount of 3% or less in
mass ratio with respect to the soft magnetic metallic glass powder,
and compression-molding the mixture using a die under a temperature
condition not lower than a softening point of the binder, the
molded body having a powder filling rate of 80% or more, a magnetic
flux density of 0.9 tesla or more when a magnetic field of
1.6.times.10.sup.4 A/m is applied, and a specific resistance of 0.1
.OMEGA.cm or more.
5. The high-frequency core according to claim 1, wherein the molded
body is obtained by preparing the mixture of the soft magnetic
metallic glass powder and the binder in an amount of 1% or less in
mass ratio with respect to the soft magnetic metallic glass powder,
and compression-molding the mixture at a temperature within a
supercooled liquid temperature range of the soft magnetic metallic
glass powder, the molded body having a powder filling rate of 90%
or more, a magnetic flux density of 1.0 tesla or more when a
magnetic field of 1.6.times.10.sup.4 A/m is applied, and a specific
resistance of 0.01 .OMEGA.cm or more.
6. The high-frequency core according to claim 1, wherein the soft
magnetic metallic glass powder is produced by water atomization or
gas atomization and at least 50% of powder particles have a size
not smaller than 10 .mu.m.
7. The high-frequency core according to claim 1, wherein a soft
magnetic alloy powder having an average diameter smaller than that
of the soft magnetic metallic glass powder and a low hardness is
added in an amount of 5-50% in volume ratio.
8. The high-frequency core according to claim 1, wherein the soft
magnetic metallic glass powder has an aspect ratio (long axis/short
axis) substantially within a range between 1 and 2.
9. The high-frequency core according to claim 1, wherein the molded
body is heat treated at a temperature not lower than a Curie point
of the alloy powder after molding, SiO.sub.2 being contained at
least in a part of an intermediate material between powder
particles of the alloy powder.
10. An inductance component comprising the high-frequency core
claimed in claim 1 and at least one turn of winding wound around
the core.
11. The inductance component according to claim 10, wherein a gap
is formed at a part of a magnetic path of the high-frequency
core.
12. The high frequency core according to claim 1, wherein the soft
magnetic metallic glass powder has a maximum particle size of 45
.mu.m or less in mesh size and an average diameter of 30 .mu.m or
less.
13. The high frequency core according to claim 12, wherein a soft
magnetic alloy powder having an average diameter smaller than that
of the soft magnetic metallic glass powder and a low hardness is
added in an amount of 5-50% in volume ratio.
14. The high-frequency core according to claim 12, wherein the soft
magnetic metallic glass powder has an aspect ratio (long axis/short
axis) substantially within a range between 1 and 2.
15. The high-frequency core according to claim 12, wherein the
powder filling rate is 50% or more and a peak value of Q is 40 or
more at 500 kHz or more.
16. The high frequency core according to claim 12, wherein the soft
magnetic metallic glass powder has a maximum powder particle size
of 45 .mu.m or less in mesh size and an average diameter of 20
.mu.m or less and a peak value of Q of the high frequency core is
50 or more at 1 MHz or more.
17. An inductance component comprising the high-frequency core
claimed in claim 12 and at least one turn of winding coil wound
around the core.
18. The inductance component according to claim 17, wherein the
winding coil is embedded in a magnetic body and formed by
press-molding into an integral structure.
19. The inductance component according to claim 17, wherein the
molded body forms at least one turn of winding coil, the winding
coil being embedded in a magnetic body and formed by press-molding
into an integral structure.
20. The inductance component according to claim 17, wherein a heat
treatment at a temperature not higher than 600.degree. C. is
performed.
21. The high-frequency core according to claim 1, wherein Fe and/or
Co is in an amount of not less than 70 atomic % and not greater
than 75 atomic %; M is in an amount of not less than 2 atomic % and
not greater than 5 atomic %; Si is in an amount of not less than 8
atomic % and not greater than 12 atomic %; and B is in an amount of
not less than 12 atomic % and not greater than 12 atomic %.
22. The high-frequency core according to claim 1, wherein the alloy
has a composition selected from the group consisting of
Fe.sub.72Si.sub.9B.sub.- 14.5Nb.sub.3Al.sub.1.0C.sub.0.5, Fe.sub.71
Si.sub.9B.sub.14.5Nb.sub.4Al.su- b.1.0C.sub.0.5,
Fe.sub.70Si.sub.9B.sub.14.5Nb.sub.5Al.sub.1.0C.sub.0.5,
Fe.sub.74Si.sub.8B.sub.13.5Nb.sub.3Al.sub.1.0C.sub.0.5,
Fe.sub.72Si.sub.10B.sub.13.5Nb.sub.3Al.sub.1.0C.sub.0.5,
Fe.sub.70Si.sub.12B.sub.13.5Nb.sub.3Al.sub.1.0C.sub.0.5,
Fe.sub.75.5Si.sub.8.5B.sub.12Nb.sub.3Al.sub.1.0C.sub.0.5,
Fe.sub.72Si.sub.8.5B.sub.15Nb.sub.3Al.sub.1.0C.sub.0.5,
Fe.sub.70Si.sub.8.5B.sub.17Nb.sub.3Al.sub.1.0C.sub.0.5,
(Fe.sub.0.9Co.sub.0.1).sub.73Si.sub.9B.sub.14.5Nb.sub.2Al.sub.1.0C.sub.0.-
5,
(Fe.sub.0.7Co.sub.0.3).sub.73Si.sub.9B.sub.14.5Nb.sub.2Al.sub.1.0C.sub.-
0.5,
(Fe.sub.0.5Co.sub.0.5).sub.73Si.sub.9B.sub.14.5Nb.sub.2Al.sub.1.0C.su-
b.0.5,
(Fe.sub.0.7Co.sub.0.3).sub.73Si.sub.9B.sub.14.5Ta.sub.2Al.sub.1.0C.-
sub.0.5,
(Fe.sub.0.7Co.sub.0.3).sub.73Si.sub.9B.sub.14.5Mo.sub.2Al.sub.1.0-
C.sub.0.5,
Fe.sub.73Si.sub.8B.sub.14.5Nb.sub.2.0Zn.sub.1.0Al.sub.1.0C.sub.-
0.5,
Fe.sub.73Si.sub.8B.sub.14.5Nb.sub.1.5Zn.sub.1.5Al.sub.1.0C.sub.0.5,
Fe.sub.73.5Si.sub.8B.sub.14.5Nb.sub.2Zn.sub.0.5Al.sub.1.0C.sub.0.5,
Fe.sub.71
Si.sub.8B.sub.14.5Nb.sub.4.5Zn.sub.0.5Al.sub.1.0C.sub.0.5,
Fe.sub.74Si.sub.8B.sub.14.5Nb.sub.1.5(misch metal).sub.0.5,
Al.sub.1.0C.sub.0.5,
(Fe.sub.0.7Co.sub.0.3).sub.74Si.sub.8B.sub.14.5Nb.su-
b.1.5Zn.sub.0.6Al.sub.1.0C.sub.0.5,
(Fe.sub.0.7Co.sub.0.3).sub.74Si.sub.8B-
.sub.14.5Ta.sub.1.6Zn.sub.0.5Al.sub.1.0C.sub.0.5,
(Fe.sub.0.7Co.sub.0.3).s-
ub.74Si.sub.8B.sub.14.5Mo.sub.1.5Zn.sub.0.5Al.sub.1.0C.sub.0.5,
Fe.sub.71.5Si.sub.9B.sub.14.5Nb.sub.3Al.sub.1.0C.sub.1.0,
Fe.sub.71.5Si.sub.9B.sub.14.5Nb.sub.3Al.sub.1.5C.sub.1.0,
Fe.sub.71Si.sub.9B.sub.14.5Nb.sub.3Al.sub.2.0C.sub.1.0,
(Fe.sub.0.8Co.sub.0.2).sub.73Si.sub.9B.sub.14.5Nb.sub.2Al.sub.1.0C.sub.0.-
5, Fe.sub.72Si.sub.9B.sub.14.5Nb.sub.3Al.sub.1.0C.sub.0.5,
Fe.sub.71.3Si.sub.9B.sub.14.5Nb.sub.3C.sub.0.7Al.sub.1.5,
Fe.sub.71.5Si.sub.9B.sub.14.5Nb.sub.3C.sub.0.5Al.sub.1.5,
Fe.sub.72.0Si.sub.9B.sub.14.5Nb.sub.3C.sub.0.5Al.sub.1.0, and
Fe.sub.73.2Si.sub.9B.sub.14.5Nb.sub.3C.sub.0.1Al.sub.0.2.
Description
[0001] This application claims priority to prior Japanese patent
application JP 2004-146595, the disclosure of which is incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a high-frequency core mainly using
a soft magnetic material and an inductance component using the
core.
[0003] Heretofore, generally as a material of a high-frequency
core, soft ferrite, high-silicon steel, an amorphous metal, a
powder core, and the like have mainly been used. The reason why the
above-mentioned materials are used is as follows. In case of the
soft ferrite, the material itself has a high specific resistance.
In case of other metal materials, the material may be formed into a
thin plate or a powder so as to reduce an eddy current although the
material itself has a low specific resistance. The above-mentioned
materials are selectively used depending upon a working frequency
or an intended use. Summarizing the reason therefor, the material
high in specific resistance, such as the soft ferrite, has a low
saturation magnetic flux density while the material high in
saturation magnetic flux density, such as the high-silicon steel,
has a low specific resistance. Thus, a magnetic material having
both of a high saturation magnetic flux density and a high specific
resistance is not yet provided.
[0004] In the meanwhile, following dramatic progress in reduction
in size and improvement in function of various electronic
apparatuses in recent years, inductance components, such as a coil
and a transformer are required to be reduced in size and to have an
inductance under a large direct current. In order to satisfy the
above-mentioned demand, it is necessary to simultaneously improve a
saturation magnetic flux density and a high-frequency loss
characteristic of the core. Further, due to copper loss resulting
from an electric resistance of a winding coil, heat generation of
the coil or the transformer is increased. Therefore, it is also
desired to provide a method for suppressing temperature
elevation.
[0005] In case of the soft ferrite, improvement of the saturation
magnetic flux density is considered but, actually, no substantial
improvement is made. In case of the high-silicon steel or the
amorphous metal, the material itself has a high saturation magnetic
flux density. However, in order to adapt to a high-frequency band,
the material must be formed into a thinner plate as the frequency
band is higher. A multilayer core using such material is lowered in
space factor, which may result in decrease in saturation magnetic
flux density.
[0006] Further, in case of the powder core, it may be possible to
achieve a high specific resistance by inserting an insulating
material between fine powder particles and to achieve a high
saturation magnetic flux density by high-density molding. However,
there are difficult problems to solve. That is, a method of
improving saturation magnetization of a soft magnetic powder used
therefor and a method of forming a high-density molded body while
maintaining insulation between powder particles are not established
at present.
[0007] In order to remedy the above-mentioned problems, in
particular, the problem that a magnetic material having both of a
saturation magnetic flux density and a high specific resistance is
difficult to obtain, proposal is made of a powder core and a method
of producing the same in which a metallic glass powder is used as a
soft magnetic powder, mixed with an insulating material, and formed
into a molded body at a temperature not lower than a normal
temperature so as to obtain a soft magnetic material having a high
permeability with a relatively excellent frequency characteristic
(see Japanese Unexamined Patent Application Publication (JP-A) No.
2001-189211, hereinafter referred to as a patent document 1).
[0008] Herein, there are various kinds of alloy compositions
collectively called a metallic glass. However, alloy compositions
used as the soft magnetic material are restricted to Fe-based
alloys which are generally classified into a PePCBSiGa alloy
composition and a FeSiBM (M being a transition metal) alloy
composition.
[0009] The patent document 1 uses the former, i.e., an alloy having
the FePcBSiGa alloy composition and discloses that, by the use of
this soft magnetic material, excellent magnetic characteristics
capable of achieving a high specific resistance and a high
saturation magnetic flux density are obtained. It is noted here
that the latter, i.e., the FeSiBM alloy composition is also
disclosed (see Japanese Unexamined Patent Application Publications
(JP-A) Nos. 2002-194514 and H11-131199, hereinafter referred to as
patent documents 2 and 3, respectively). Further, it is also
disclosed to use the soft magnetic material for a core (see
Japanese Unexamined Patent Application Publication (JP-A) No.
H11-74111, hereinafter referred to as a patent document 4).
[0010] On the other hand, it is disclosed to form a winding coil
and a metal powder into an integral structure with a reduced size
so that d.c. superposition characteristics are improved (see
Japanese Unexamined Patent Application Publications (JP-A) Nos.
H04-286305 and 2002-305108, hereinafter referred to as patent
documents 5 and 6, respectively).
[0011] In case of the above-mentioned soft magnetic materials
suitable as the high-frequency core, for example, in case of the
FePCBSiGa alloy composition disclosed in the patent document 1,
magnetic characteristics including a high permeability with a
relatively excellent frequency characteristic are obtained. In this
case, however, it is necessary to use an expensive metal such as
Ga. This results in a problem that the material itself is high in
cost and, therefore, promotion of industrial application is
inhibited.
[0012] On the other hand, in the FeSiBM alloy composition disclosed
in the patent documents 2 and 3 and considered about application to
the core in the patent document 4, the material itself is excellent
in economical efficiency. However, in these patent documents, no
technique for obtaining a high specific resistance and a high
magnetic flux density is shown (this is presumably because a method
of forming a powder and a method of forming a molded body which are
suitable for the alloy composition are not found). Thus, at
present, it is difficult to use the material for the high-frequency
core and an inductance component using the same.
[0013] The patent documents 5 and 6 disclose reduction in size of
the coil. However, because an existing soft magnetic metal material
is used, reduction of loss is not sufficient.
SUMMARY OF THE INVENTION
[0014] It is an object of this invention to provide an inexpensive
high-frequency core made of a soft magnetic material having a high
saturation magnetic flux density and a high specific resistance and
to provide an inductance component using the same.
[0015] According to one aspect of the present invention, there is
provided a high-frequency core which includes a molded body
obtained by molding a mixture of a soft magnetic metallic glass
powder and a binder in an amount of 10% or less in mass ratio with
respect to the soft magnetic metallic glass powder. The soft
magnetic metallic glass powder has an alloy composition represented
by (Fe.sub.1-aCo.sub.a).sub.100-x-y-z-q-r(M-
.sub.1-pM'.sub.p).sub.xT.sub.yB.sub.zC.sub.qAl.sub.r(0<a<0.50,
0<p<0.5, 2 atomic %<x<5 atomic %, 8 atomic %<y<12
atomic %, 12 atomic %<z<17 atomic %, 0.1 atomic %<q<1.0
atomic %, 0.2 atomic %<r<2.0 atomic % and
25<(x+y+z+q+r)<30, M being at least one selected from Zr, Nb,
Ta, Hf, Mo, Ti, V, Cr, and W, M' being at least one selected from
Zn, Sn, and R (R being at least one element selected from rare
earth metals including Y), T being at least one selected from Si
and P).
[0016] According to another aspect of the present invention, there
is provided an inductance component which includes the
high-frequency core and at least one turn of winding wound around
the core.
[0017] According to still another of the present invention, there
is provided an inductance component which includes the
high-frequency core and at least one turn of winding coil wound
around the core.
BRIEF DESCRIPTION OF THE DRAWING
[0018] FIG. 1 is an external perspective view showing a basic
structure of a high-frequency core according to one embodiment of
this invention;
[0019] FIG. 2 is an external perspective view of an inductance
component comprising the high-frequency core illustrated in FIG. 1
and a winding wound therearound;
[0020] FIG. 3 is an external perspective view of a basic structure
of a high-frequency core according to another embodiment of this
invention;
[0021] FIG. 4 is an external perspective view of an inductance
component comprising the high-frequency core illustrated in FIG. 3
and a winding wound therearound; and
[0022] FIG. 5 is an external perspective view of a basic structure
of an inductance component according to yet another embodiment of
this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] This invention will be described in detail.
[0024] As a result of extensive studies, the present inventors have
found out that, if an alloy composition of
(Fe.sub.1-aCo.sub.a).sub.100-x-y-z-q-
-r(M.sub.1-pM'.sub.p).sub.xT.sub.yB.sub.zC.sub.qAl.sub.r(0<a<0.50,
0<p<0.5, 2 atomic %<x<5 atomic %, 8 atomic %<y<12
atomic %, 12 atomic %<z<17 atomic %, 0.1 atomic %<q<1.0
atomic %, 0.2 atomic %<r<2.0 atomic % and
25<(x+y+z+q+r)<30, M being at least one selected from Zr, Nb,
Ta, Hf, Mo, Ti, V, Cr, and W, M' being at least one selected from
Zn, Sn, and R (R being at least one element selected from rare
earth metals including Y), T being at least one selected from Si
and P) is selected as a soft magnetic metallic glass powder
excellent in economic efficiency, the powder excellent in magnetic
characteristics and glass forming performance is obtained. In the
present invention, "rare earth metals including Y" represent the
group consisting of lanthanum series elements, such as La, Ce, Pr,
Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and another
element of Y It has also been found out that, if a powder core is
obtained by subjecting the powder to oxidization or insulating
coating and then forming the powder into a molded body by an
appropriate molding method using a die or the like, the powder core
is a high-permeability powder core exhibiting an excellent
permeability over a wide band and an excellent performance which
has never been achieved, and that, as a result, a high-frequency
core made of a soft magnetic material having a high saturation
magnetic flux density and a high specific resistance can be
produced at a low cost.
[0025] Further, it has been found out that an inductance component
obtained by providing the high-frequency core with at least one
turn of winding is inexpensive and has a high performance as never
before.
[0026] The present inventors also found out that, by limiting a
particle size of the soft magnetic metallic glass powder
represented by the above-mentioned composition formula, the powder
core is excellent in core loss at a high frequency.
[0027] Further, it has been found out that an inductance component
obtained by providing the high-frequency core with at least one
turn of winding is inexpensive and has a high performance as never
before. It is also found out that, by press forming in the state
where a winding coil is embedded in a magnetic body to form an
integral structure, an inductance component adapted to a
high-frequency large-current application is obtained.
[0028] In order to increase the specific resistance of the molded
body, the alloy powder before molding may be subjected to oxidizing
heat treatment in atmospheric air. In order to form the molded body
having a high density, molding may be carried out at a temperature
not lower than a softening point of the resin as the binder. In
order to achieve a higher density of the molded body, molding may
be carried out in a supercooled liquid temperature range of the
alloy powder.
[0029] Specifically, the soft magnetic metallic glass powder has an
alloy composition represented by a formula
(Fe.sub.1-aCo.sub.a).sub.100-x-y-z-q-
-r(M.sub.1-pM'.sub.p).sub.xT.sub.yB.sub.zC.sub.qAl.sub.r(0<a<0.50,
0<p<0.5, 2 atomic %<x<5 atomic %, 8 atomic %<y<12
atomic %, 12 atomic %<z<17 atomic %, 0.1 atomic %<q<1.0
atomic %, 0.2 atomic %<r<2.0 atomic % and
25<(x+y+z+q+r)<30, M being at least one selected from Zr, Nb,
Ta, Hf, Mo, Ti, V, Cr, and W, M' being at least one selected from
Zn, Sn, and R (R being at least one element selected from rare
earth metals including Y), T being at least one selected from Si
and P). The molded body is obtained by molding a mixture of the
soft magnetic metallic glass powder and a binder of a predetermined
amount in mass ratio with respect to the soft magnetic metallic
glass powder.
[0030] Herein, description will be made of the alloy composition of
the soft magnetic metallic glass powder. Fe as a main component is
an element contributing to magnetism and is essential in order to
achieve a high saturation magnetic flux density. A part of Fe may
be replaced by Co in a ratio of 0 to 0.5. Such substitute component
has an effect of improving a glass forming performance and is
further expected to have an effect of improving the saturation
magnetic flux density. The total amount of Fe and the substitute
element is within a range not smaller than 70 atomic % and not
greater than 75 atomic % with respect to a whole of the alloy
powder. This is because, unless the amount is 70 atomic % or more,
the saturation magnetic flux density is too low and the usefulness
is lost and, if the amount is greater than 75 atomic %, the
permeability of the core and the core loss are degraded due to
crystallization.
[0031] The element M is a transition metal element necessary to
improve the glass forming performance and is at least one selected
from Zr, Nb, Ta, Hf. Mo, Ti, V, Cr, and W. The content of the
element M is not smaller than 2 atomic % and not greater than 5
atomic %.
[0032] This is because if the content is smaller than 2 atomic %,
the glass forming performance is decreased and the permeability and
the core loss are remarkably deteriorated and, if the content
exceeds 5 atomic %, the saturation magnetic flux density is
decreased and the usefulness is lost. By replacing the ratio of 0
to 0.5 of the element M by Zn, Sn, R (R being at least one element
selected from rare earth metals including Y), the ratio of Fe and
Co can be increased without deteriorating the glass forming
performance, so that the saturation magnetic flux density can be
Improved.
[0033] Si and B are elements which are essential in order to
produce the soft magnetic metallic glass powder. The amount of Si
is within a range not smaller than 8 atomic % and not greater than
12 atomic %. The amount of B is within a range not smaller than 12
atomic % and not greater than 17 atomic %. This is because, if the
amount of Si is smaller than 8 atomic % or greater than 12 atomic %
or if the amount of B is smaller than 12 atomic % or greater than
17 atomic %, the glass forming performance is degraded and a stable
soft magnetic glass powder can not be produced. Herein, Si may be
replaced by P.
[0034] Al and C have an effect of forming the powder into a
spherical shape upon preparing the powder by various atomizing
techniques as far as these elements are used within the range of
the alloy composition of this invention together with other
constituent elements. As regards the amounts to be added, if the
amount of Al is smaller than 0.2 atomic %, the effect of forming
the powder of a spherical shape is small. If the amount of Al is
greater than 2.0 atomic %, amorphous forming performance is
deteriorated. Similarly, if the amount of C is smaller than 0.1
atomic %, the effect of forming the powder of a spherical shape is
small. If the amount of C is greater than 1.0 atomic %, amorphous
forming performance is deteriorated. Al and C may be used alone or
in combination.
[0035] The soft magnetic metallic glass powder is produced by water
atomization or gas atomization. Preferably, at least 50% of
particle sizes are not smaller than 10 .mu.m. In particular, the
water atomization is established as a method of producing the alloy
powder at a low cost and in a large amount. To be able to produce
the powder by this method is a very large advantage in industrial
application. However, in case of a conventional amorphous
composition, the alloy powder of 10 .mu.m or more is crystallized
so that the magnetic characteristics are significantly
deteriorated. As a result, the product yield is seriously
deteriorated so that the industrial application is prevented. On
the other hand, the soft magnetic metallic glass powder according
to this invention is easily vitrified (amorphized) if the particle
size is 150 .mu.m or less. Therefore, the product yield is high.
Thus, the soft magnetic metallic glass powder of this invention is
highly advantageous in view of the cost. In addition, in the alloy
powder produced by water atomization, an appropriate oxide coating
film is already formed on a powder surface. Therefore, by mixing a
resin with the alloy powder and molding the mixture to form a
molded body, a core having a high specific resistance is easily
obtained.
[0036] In either of the alloy powder produced by water atomization
and the alloy powder produced by gas atomization, a more excellent
oxide coating film is formed if heat treatment is carried out in
atmospheric air under a temperature condition not higher than a
crystallization temperature of the alloy powder used. In this
event, the specific resistance of the core can be increased so that
the core loss of the core can be reduced.
[0037] On the other hand, for an inductance component intended for
higher-frequency applications, an eddy current loss can be reduced
by the use of a metal powder having a very small particle size.
However, with an alloy composition known in the art, oxidation of
the powder during production is remarkable if the average diameter
is 30 .mu.m or less. Therefore, predetermined characteristics are
difficult to obtain in the powder produced by a typical water
atomization apparatus. However, the metallic glass powder is
excellent in corrosion resistance of the alloy and is therefore
advantageous in that the powder reduced in amount of oxygen and
having excellent characteristics can relatively easily be produced
even if the powder is very small.
[0038] Next, the method of molding the molded body will be
described. Basically, a binder such as a silicone resin in an
amount of 10% in mass ratio is mixed with the soft magnetic
metallic glass powder. Using a die or by molding, the molded body
is obtained. The molded body serves as a high-frequency core having
a powder filling rate of 50% or more, a magnetic flux density of
0.5 T or more upon application of a magnetic field of
1.6.times.10.sup.4 A/m, and a specific resistance of
1.times.10.sup.4 cm. Herein, the amount of the binder is 10% or
less in mass ratio. This is because, if the amount exceeds 10%, the
saturation magnetic flux density becomes equivalent to or lower
than that of ferrite and the usefulness of the core is lost.
[0039] The molded body may be obtained by preparing a mixture of
the soft magnetic metallic glass powder and the binder in an amount
of 5% or less in mass ratio with respect to the soft magnetic
metallic glass powder and compression-molding the mixture using a
die. In this case, the molded body has a powder filling rate of 70%
or more, a magnetic flux density of 0.75 T or more when a magnetic
field of 1.6.times.10.sup.4 A/m is applied, and a specific
resistance of 1 .OMEGA.cm or more. When the magnetic flux density
is 0.75 T or more and the specific resistance is 1 .OMEGA.m or
more, the characteristics are more excellent as compared with a
Sendust core and the usefulness is further improved.
[0040] Further, the molded body may be obtained by preparing a
mixture of the soft magnetic metallic glass powder and the binder
in an amount of 3% or less in mass ratio with respect to the soft
magnetic metallic glass powder and compression-molding the mixture
using a die under a temperature condition not higher than a
softening point of the binder. In this case, the molded body has a
powder filling rate of 80% or more, a magnetic flux density of 0.9
T or more when a magnetic field of 1.6.times.10.sup.4A/m is
applied, and a specific resistance of 0.1 .OMEGA.cm or more. When
the magnetic flux density is 0.9 T or more and the specific
resistance is 0.1 .OMEGA.m or more, the characteristics are more
excellent as compared with any powder core commercially available
at present and the usefulness is further improved.
[0041] Further, the molded body may be obtained by preparing a
mixture of the soft magnetic metallic glass powder and the binder
in an amount of 1% or less in mass ratio with respect to the soft
magnetic metallic glass powder and compression-molding the mixture
in a supercooled liquid temperature range of the soft magnetic
metallic glass powder. In this case, the molded body has a powder
filling rate of 90% or more, a magnetic flux density of 1.0 T or
more when a magnetic field of 1.6.times.10.sup.4 A/m is applied,
and a specific resistance of 0.01 .OMEGA.cm or more. When the
magnetic flux density is 1.0 T or more and the specific resistance
is 0.01 .OMEGA.m or more, the magnetic flux density is
substantially equivalent to that of a multilayer core including an
amorphous metal and a high-silicon steel plate in a practical
region. However, the molded body herein obtained is small in
hysteresis loss and high in specific resistance so that the core
loss characteristic is much superior. Thus, the usefulness as a
core is further improved.
[0042] Furthermore, after molding, the molded body as the
high-frequency core may be subjected to heat treatment under a
temperature condition not higher than the Curie point as a
strain-relieving heat treatment. In this event, the core loss is
further reduced and the usefulness as a core is further improved.
Herein, it is desired that SiO.sub.2 is contained at least in a
part of an intermediate material between particles of the alloy
powder in order to maintain insulation between the particles
(alternatively, all of the intermediate material may be
SiO.sub.2).
[0043] If an inductance component is produced by providing the
above-mentioned high-frequency core with at least one turn of
winding after a gap is formed at a part of a magnetic path if
necessary, a product exhibiting high permeability in a high
magnetic field and having excellent characteristics is
produced.
[0044] Hereinafter, this invention will be described further in
detail with reference to the drawing.
[0045] FIG. 1 is an external perspective view showing a basic
structure of a high-frequency core 1 according to one embodiment of
this invention. FIG. 1 shows a state where the high-frequency core
1 using the above-mentioned soft magnetic metallic glass powder is
formed into a ring-shaped plate.
[0046] FIG. 2 is an external perspective view showing an inductance
component 101 obtained by providing the high-frequency core 1 with
a winding. FIG. 2 shows a state where a predetermined number of
turns of winding 3 is wound around the high-frequency core 1 as the
ring-shaped plate to produce the inductance component 101 with lead
wire extracting parts 3a and 3b.
[0047] FIG. 3 shows an external perspective view of a basic
structure of a high-frequency core 1 according to another
embodiment of this invention. FIG. 3 shows a state where the
high-frequency core 1 using the abovementioned soft magnetic
metallic glass powder is formed into a ring-shaped plate and a gap
2 is formed at a part of a magnetic path.
[0048] FIG. 4 is an external perspective view of an inductance
component 102 obtained by providing the high-frequency core 1
having the gap 2 with the winding 3. FIG. 4 shows a state where a
predetermined number of turns of winding 3 is wound around the
high-frequency core 1 as the ring-shaped plate having the gap 2 to
produce the inductance component with the lead wire extracting
parts 3a and 3b.
[0049] If a powder core is produced by molding a mixture of a soft
magnetic metallic glass powder having the above-mentioned metallic
glass composition and having the maximum particle size of 45 .mu.m
or less in mesh size and the average diameter of 30 .mu.m or less
and a binder in an amount of 10% or less in mass ratio with respect
to the soft magnetic metallic glass powder, the powder core
exhibits an extremely low loss characteristic at a high frequency
and has an excellent performance never before achieved. By
providing the powder core with a winding, the inductance component
excellent in Q characteristic is obtained.
[0050] Further, by press-molding a magnetic body with a winding
coil embedded therein to form an integral structure, an inductance
component adapted to a large high-frequency current is
obtained.
[0051] Herein, the reason why the powder particle size is defined
will be described in detail. If the maximum particle size exceeds
45 .mu.m in mesh size, the Q characteristic in a high-frequency
region is deteriorated. Further, unless the average diameter is 30
.mu.m or less, the Q characteristic at 500 kHz or more does not
exceed 40. Further, unless the average diameter is 20 .mu.m or
less, the Q value at 1 MHz or more is not 50 or more. The metallic
glass powder is advantageous in that, since the specific resistance
of the alloy itself is twice to ten times higher than conventional
materials, the Q characteristic is high even at the same particle
size. If the same Q characteristic is sufficient, a usable particle
size range is widened so as to reduce a powder production cost.
[0052] FIG. 5 is an external perspective view of a basic structure
of a high-frequency inductance component according to yet another
embodiment of this invention. Referring to FIG. 5, the inductance
component 103 as an integral structure is obtained by press-molding
in the state where a winding coil 7 obtained by winding a long
plate material 5 formed by the above-mentioned soft magnetic powder
is embedded in a magnetic body 8. An entire surface of a winding
portion of the plate material 5 is provided with an insulating
coating 6.
[0053] Now, the high-frequency core according to this invention and
the inductance component using the same will be described in
conjunction with several examples and comparative examples,
including production processes.
EXAMPLES 1-26, COMPARATIVE EXAMPLES 1-11
[0054] At first, as a powder preparing step, pure metal element
materials including Fe, Si, B. Nb, Al, C, and substitute elements
therefor or, if desired, various mother alloys were weighed so as
to obtain predetermined compositions. By the use of these
materials, various kinds of soft magnetic alloy powders were
produced by water atomization generally used. It is noted here that
a misch metal is a mixture of rare earth metals. Herein, a mixture
of 30% La, 50% Ce, 15% Nd, and the balance other rare earth element
or elements was used.
[0055] Next, as a molded body preparing step, each of the alloy
powders was classified into those having a powder size of 45 .mu.m
or less. Thereafter, a silicone resin as a binder was mixed in an
amount of 4% in mass ratio. Then, by the use of a die with a groove
having an outer diameter of hope .phi..sub.OUT=27 mm.times.an inner
diameter .phi..sub.IN=14 mm, various kinds of molded bodies were
formed by applying a pressure of 1.18 GPa (about 12 t/cm.sup.2) at
a room temperature so that the height was equal to 5 mm.
[0056] Further, the various kinds of molded bodies were subjected
to resin curing. Thereafter, the weight and the size of each molded
body were measured. Then, an appropriate number of turns of winding
was provided to prepare various kinds of inductance components
(having the shape illustrated in FIG. 2).
[0057] Next, for each of various samples of the inductance
components, the permeability was obtained from the inductance value
at 100 kHz by the use of an LCR meter. Further, by the use of a
d.c. magnetic characteristics measuring instrument, measurement was
made of the saturation magnetic flux density when a magnetic field
of 1.6.times.10.sup.4 A/m was applied. In addition, upper and lower
surfaces of each core were polished and measurement by X-ray
diffraction (XRD) was carried out to observe a phase. The results
shown in Table 1 were obtained.
1 TABLE 1-1 magnetic flux permea- XRD density/T at bility at
measurement alloy composition 1.6 .times. 10.sup.4 A/m 100 kHz
result comparative
Fe.sub.72.5Si.sub.9B.sub.14.5Nb.sub.2.5Al.sub.1.0C.sub.0.5 0.85/T
22 crystal phase example 1 example 1 Fe.sub.72Si.sub.9B.sub.14-
.5Nb.sub.3Al.sub.1.0C.sub.0.5 0.82 31 glass phase example 2
Fe.sub.71Si.sub.9B.sub.14.5Nb.sub.4Al.sub.1.0C.sub.0.5 0.77 33
glass phase example 3
Fe.sub.70Si.sub.9B.sub.14.5Nb.sub.5Al.sub.1.0C.sub- .0.5 0.72 35
glass phase comparative Fe.sub.69Si.sub.9B.sub.14.5Nb.-
sub.6Al.sub.1.0C.sub.0.5 0.67 37 glass phase example 2 comparative
Fe.sub.74.3Si.sub.7.7B.sub.13.5Nb.sub.3Al.sub.1.0C.sub.0.5 0.92 19
crystal phase example 3 example 4
Fe.sub.74Si.sub.8B.sub.13.5Nb.sub.3Al.sub.1.0C.sub.0.5 0.91 30
glass phase example 5
Fe.sub.72Si.sub.10B.sub.13.5Nb.sub.3Al.sub.1.0C.su- b.0.5 0.82 32
glass phase example 6 Fe.sub.70Si.sub.12B.sub.13.5Nb.-
sub.3Al.sub.1.0C.sub.0.5 0.72 34 glass phase comparative
Fe.sub.69.5Si.sub.12.5B.sub.13.5Nb.sub.3Al.sub.1.0C.sub.0.5 0.69 21
crystal phase example 4 comparative Fe.sub.75.5Si.sub.8.5B.-
sub.11.5Nb.sub.3Al.sub.1.0C.sub.0.5 0.94 20 crystal phase example 5
example 7 Fe.sub.75Si.sub.8.5B.sub.12Nb.sub.3Al.sub.1.0C.sub.0.5
0.93 33 glass phase example 8 Fe.sub.72Si.sub.8.5B.sub.15Nb.sub.3A-
l.sub.1.0C.sub.0.5 0.82 35 glass phase example 9
Fe.sub.70Si.sub.8.5B.sub.17Nb.sub.3Al.sub.1.0C.sub.0.5 0.72 37
glass phase comparative
Fe.sub.69.5Si.sub.8.5B.sub.17.5Nb.sub.3Al.sub.1.- 0C.sub.0.5 0.70
23 crystal phase example 6 example 10
(Fe.sub.0.9Co.sub.0.1).sub.73Si.sub.9B.sub.14.5Nb.sub.2Al.sub.1.0C.sub.0.-
5 0.87 31 glass phase example 11
(Fe.sub.0.7Co.sub.0.3).sub.73Si.su-
b.9B.sub.14.5Nb.sub.2Al.sub.1.0C.sub.0.5 0.89 33 glass phase
example 12
(Fe.sub.0.5Co.sub.0.5).sub.73Si.sub.9B.sub.14.5Nb.sub.2Al.sub.-
1.0C.sub.0.5 0.87 35 glass phase comparative
(Fe.sub.0.4Co.sub.0.6).sub.73Si.sub.9B.sub.14.5Nb.sub.2Al.sub.1.0C.sub.0.-
5 0.85 37 glass phase example 7 example 13
(Fe.sub.0.7Co.sub.0.3).sub.73Si.sub.9B.sub.14.5Ta.sub.2Al.sub.1.0C.sub.0.-
5 0.88 34 glass phase example 14
(Fe.sub.0.7Co.sub.0.3).sub.73Si.su-
b.9B.sub.14.5Mo.sub.2Al.sub.1.0C.sub.0.5 0.87 35 glass phase
example 15
Fe.sub.73Si.sub.8B.sub.14.5Nb.sub.2.0Zn.sub.1.0Al.sub.1.0C.sub-
.0.5 0.86 37 glass phase example 16
Fe.sub.73Si.sub.8B.sub.14.5Nb.s-
ub.1.5Zn.sub.1.5Al.sub.1.0C.sub.0.5 0.86 35 glass phase comparative
Fe.sub.73Si.sub.8B.sub.14.5Nb.sub.1.0Zn.sub.2.0Al.sub.1.0C.sub.0.5
0.86 19 crystal phase example 8 example 17
Fe.sub.73.5Si.sub.8B.sub.14.5Nb.sub.2Zn.sub.0.5Al.sub.1.0C.sub.0.5
0.89 33 glass phase example 18
Fe.sub.71Si.sub.8B.sub.14.5Nb.sub.4.5Zn.-
sub.0.5Al.sub.1.0C.sub.0.5 0.77 37 glass phase comparative
Fe.sub.70.5Si.sub.8B.sub.14.5Nb.sub.5Zn.sub.0.5Al.sub.1.0C.sub.0.5
0.74 35 crystal phase example 9 example 19
Fe.sub.74Si.sub.0B.sub.14.5Nb.sub.1.5Sn.sub.0.5Al.sub.1.0C.sub.0.5
0.91 35 glass phase example 20 Fe.sub.74Si.sub.8B.sub.14.5(misch
metal).sub.0.5Al.sub.1.0C.sub.0.5 0.90 35 glass phase example 21
(Fe.sub.0.7Co.sub.0.3).sub.74Si.sub.6B.sub.14.5Nb.sub.1.5Zn.sub.0.5Al.sub-
.1.0C.sub.0.5 0.93 33 glass phase example 22
(Fe.sub.0.7Co.sub.0.3).sub.74Si.sub.6B.sub.14.5Ta.sub.1.5Zn.sub.0.5Al.sub-
.1.0C.sub.0.5 0.92 32 glass phase example 23
(Fe.sub.0.7Co.sub.0.3).sub.74Si.sub.6B.sub.14.5Mo.sub.1.5Zn.sub.0.5Al.sub-
.1.0C.sub.0.5 0.91 34 glass phase example 24
Fe.sub.71.5Si.sub.9B.sub.14.5Nb.sub.3Al.sub.1.0C.sub.1.0 0.79 33
glass phase comparative
Fe.sub.71.3Si.sub.9B.sub.14.5Nb.sub.3Al.sub.1.0C- .sub.1.2 0.77 16
crystal phase example 10 example 25
Fe.sub.71.5Si.sub.9B.sub.14.5Nb.sub.3Al.sub.1.5C.sub.0.5 0.79 33
glass phase example 26
Fe.sub.71Si.sub.9B.sub.14.5Nb.sub.3Al.sub.2.0C.su- b.0.5 0.79 33
glass phase comparative Fe.sub.70.8Si.sub.9B.sub.14.5-
Nb.sub.3Al.sub.2.2C.sub.0.5 0.76 15 crystal phase example 11
[0058] Table 1 shows composition ratios of the samples. Further, an
XRD pattern obtained by XRD measurement is judged as a glass phase
if only a broad peak specific to the glass phase was detected, as a
(glass+crystal) phase if a sharp peak attributable to a crystal was
observed together with a broad peak, and as a crystal phase if only
a sharp peak was observed without a broad peak.
[0059] For those samples of the compositions with the glass phase,
a glass transition temperature and a crystallization temperature
were measured as thermal analysis by DSC to confirm that a
supercooled liquid temperature range .DELTA.Tx was 30 K or higher
for all those samples. Herein, .times.Tx=Tx-Tg, where Tx represents
crystallization temperature, and Tg represents glass transition
temperature. The specific resistance was measured for the molded
bodies (cores) by two-terminal d.c. measurement. As a result, it
was confirmed that all samples exhibited excellent specific
resistances not lower than 1 .OMEGA.cm.
[0060] The temperature elevation rate of DSC was 40 K/min. From the
examples 1 to 3 and the comparative examples 1 and 2, it is
understood that the core having a glass phase is obtained if the
amount of Nb is 3 to 6%.
[0061] However, it is seen that the magnetic flux density is as low
as 0.70 T or less in the comparative example 2 where the amount of
Nb is 6%.
[0062] From the examples 4 to 9 and the comparative examples 3 to
6, it is understood that the core having a glass phase is obtained
if the amount of Si is 8 to 12, the amount of B is 12 to 17, and
the amount of Fe is 70 to 75.
[0063] From the examples 10 to 14 and the comparative example 7, it
is understood that, by replacing a part of Fe with Co, the metallic
glass powder is obtained even if the amount of Nb is 2%. However,
it is seen that, if the replaced amount exceeds 0.5, the effect of
improving the magnetic flux density is not obtained. It is also
understood that the similar effect is obtained by the use of Ta or
Mo instead of Nb.
[0064] From the examples 15 and 16 and the comparative example 8,
it is understood that the saturation magnetic flux density is
improved by replacing Nb by Zn but the glass phase can not be
formed if the replacement ratio exceeds 0.5.
[0065] As to the total amount of Zn and Nb, it is understood that
5% or less is appropriate from the examples 17 and 18 and the
comparative example 9. From the examples 19 and 20, it is
understood that the similar effect is obtained if Sn or a misch
metal is added instead of Zn.
[0066] From the examples 21 to 23, it is understood that the
similar effect is obtained if a part of Fe is replaced by Co and
that the similar effect is obtained if Ta or Mo is used instead of
Nb. As shown in the examples 24 to 26 and the comparative examples
11 and 12, Al may be added in a ratio of 2.0 or less and C may be
added in a ratio of 1.0 or less. However, if a greater amount is
added, an ability of forming an amorphous structure is remarkably
deteriorated.
EXAMPLE 27
[0067] An alloy powder having a composition of
(Fe.sub.0.8Co.sub.0.2).sub.-
73Si.sub.9B.sub.14.5Nb.sub.2Al.sub.1.0C.sub.0.5 was prepared by
water atomization. The powder thus obtained was classified into
those having a size of 75 .mu.m or less. XRD measurement was
carried out to confirm a broad peak specific to a glass phase.
[0068] Next, thermal analysis by DSC was carried out to measure a
glass transition temperature and a crystallization temperature to
find out that .DELTA.Tx was 35K. Then, the powder was heat treated
at 450.degree. C. lower than the glass transition temperature for
0.5 hour in atmospheric air to form oxide on the surface of the
powder. Next, the powder was mixed with 10%, 5%, 2.5%, 1%, and 0.5%
silicone resin. By the use of a die of .phi.27.times..phi.14, these
powders were molded under three conditions at a room temperature,
at 150.degree. C. higher than a softening temperature of the resin,
and at 550.degree. C. in a supercooled liquid temperature range of
this metallic glass powder. The powder filling rate, the magnetic
flux density by d.c. magnetic characteristics measurement, and the
d.c. specific resistance were measured. The results are shown in
Table 2.
2TABLE 2 resin powder magnetic flux specific sample content molding
filling rate density/T at resistance No. (%) temperature (%) 1.6
.times. 10.sup.4 A/m .OMEGA.cm 1 0.5% room 69.5 0.93 >100
temperature 2 1% room 70.3 0.95 >100 temperature 3 2.5% room
71.1 0.97 >100 temperature 4 5% room 70.5 0.97 >100
temperature 5 10% room 52.1 0.66 >10.sup.4 temperature 6 0.5%
150.degree. C. 81.3 1.12 5 7 1% " 81.9 1.14 10 8 2.5% " 82.5 1.16
15 9 5% " 71.0 0.95 >100 10 10% " 52.6 0.67 >10.sup.4 11 0.5%
550.degree. C. 96.0 1.37 0.1 12 1% " 92.8 1.31 0.5 13 2.5% " 83.0
1.15 10 14 5% " 71.4 0.97 >100 15 10% " 52.3 0.67
>10.sup.4
[0069] As seen from Table 2, the specific resistance has a value as
high as .gtoreq.10.sup.4 comparable to that of a ferrite core when
the amount of the binder exceeds 5%. Because no special effect is
obtained even if the molding temperature is elevated, molding at
the room temperature is sufficient. Next, when the amount of the
binder is equal to 5%, the specific resistance as high as 100
.OMEGA.cm or more is obtained and molding at the room temperature
is sufficient. Next, it is understood that, when the content of the
binder is equal to 2.5%, the powder filling rate is dramatically
improved, the magnetic flux density is high, and the specific
resistance of 10 .OMEGA.cm or more is obtained if molding is
carried out at 150.degree. C. Next, it is understood that, when the
amount of the binder is 1% and 0.5%, the powder filling rate is
dramatically improved, the saturation magnetic flux density is
high, and the specific resistance of 0.1 .OMEGA.cm or more is
obtained if molding is carried out at 550.degree. C.
EXAMPLE 28
[0070] In an example 28, an alloy powder having a composition of
Fe.sub.72Si.sub.9B.sub.14.5Nb.sub.3Al.sub.1.0C.sub.0.5 was prepared
by water atomization. Thereafter, the powder thus obtained was
classified into those having a particle size of 75 .mu.m or less.
Then, XRD measurement was carried out to confirm a broad peak
specific to a glass phase.
[0071] Further, thermal analysis by DSC was carried out to measure
a glass transition temperature and a crystallization temperature to
confirm that a vitrification start temperature range or a
supercooled liquid temperature range .DELTA.Tx was 35K. Then, the
powder was kept at a temperature condition of 450.degree. C. lower
than the glass transition temperature and heat treated for 0.5 hour
in atmospheric air to form oxide on the surface of the powder.
[0072] Next, the powder with oxide formed thereon was mixed with,
in mass ratio, 10%, 5%, 2.5%, 1%, and 0.5% silicone resin as a
binder. By the use of a die with a groove having an outer diameter
.phi..sub.OUT=27 mm.times.an inner diameter .phi..sub.IN=14 mm,
these powders were molded by applying a pressure of 1.18 GPa (about
12 t/cm.sup.2) as a molding pressure under three different
temperature conditions, i.e., at a room temperature, at 150.degree.
C. higher than a softening temperature of the resin, and at
550.degree. C. in a supercooled liquid temperature range of the
soft magnetic metallic glass powder, so that the height was equal
to 5 mm. Thus, various kinds of molded bodies were produced.
[0073] Next, the various kinds of molded bodies thus obtained were
subjected to resin curing. Thereafter, the weight and the size of
each molded body were measured. Then, an appropriate number of
turns of winding was provided to prepare various kinds of
inductance components (having the shape illustrated in FIG. 2).
[0074] Then, for each of various samples (Nos. 1-15) of the
inductance components, the powder filling rate %, the magnetic flux
density (at 1.6.times.10.sup.4 A/m) by d.c. magnetic
characteristics measurement, and the d.c. specific resistance
.OMEGA.cm were measured. The results shown in Table 3 were
obtained.
3TABLE 3 resin powder magnetic flux specific sample content molding
filling rate density/T at resistance No. (%) temperature (%) 1.6
.times. 10.sup.4 A/M .OMEGA.cm 1 0.5% room 69.1 0.84 >100
temperature 2 1.0% room 69.9 0.85 >100 temperature 3 2.5% room
70.9 0.86 >100 temperature 4 5.0% room 70.4 0.85 >100
temperature 5 10% room 51.6 0.56 >10.sup.4 temperature 6 0.5%
150.degree. C. 80.9 1.04 5 7 1.0% 150.degree. C. 81.6 1.06 10 8
2.5% 150.degree. C. 82.3 1.08 15 9 5.0% 150.degree. C. 70.7 0.86
>100 10 10% 150.degree. C. 52.1 0.58 >10.sup.4 11 0.5%
550.degree. C. 95.8 1.26 0.1 12 1.0% 550.degree. C. 92.5 1.21 0.5
13 2.5% 550.degree. C. 82.6 1.08 10 14 5.0% 550.degree. C. 71.1
0.87 >100 15 10% 550.degree. C. 51.8 0.58 >10.sup.4
[0075] As seen from Table 3, the specific resistance has a value as
high as .gtoreq.10.sup.4 comparable to that of a ferrite core when
the amount of the binder (the amount of the resin) exceeds 5%. It
is understood that no special effect is obtained even if the
molding temperature is elevated and that the molding condition
around the room temperature is sufficient. Further, it is
understood that, when the amount of the resin is equal to 5%, the
specific resistance as high as 100 .OMEGA.cm or more is obtained
and that molding at the room temperature is similarly
sufficient.
[0076] Further, it is understood that, when the amount of the resin
is equal to 2.5%, the powder filling rate is dramatically improved,
the magnetic flux density is high, and the specific resistance of
10 .OMEGA.cm or more is obtained if molding is carried out at
150.degree. C. In addition, it is understood that, when the amount
of the resin is 1% and 0.5%, the powder filling rate is
dramatically improved, the saturation magnetic flux density is
high, and the specific resistance of 0.1 .OMEGA.cm or more is
obtained if molding is carried out at 550.degree. C.
EXAMPLE 29
[0077] By the use of the sample No. 12 in the example 27, the
inductance characteristic was measured in comparison with various
core materials. Further, a core prepared by the use of the same
alloy powder and the same production process was heat treated at
500.degree. C. for 0.5 hour in a nitrogen atmosphere to obtain
another sample. The inductance characteristic of this sample is
also shown. For standardization of the inductance value, the
permeability was obtained for comparison. The core materials
compared were Sendust, 6.5% silicon steel, and an iron-based
amorphous metal.
4TABLE 4 magnetic flux specific sample density/T at resistance
permeability core loss name 1.6 .times. 10.sup.4 A/M .OMEGA.cm --
20 kHz 0.1 T this invention 1.31 0.5 150 50/mW/cc this invention
1.33 0.4 200 30 (heat treated) MnZn ferrite 0.55 >10.sup.4 100*
10 Sendust 0.65 100 80 100 6.5% silicon 1.0 100 .mu. 100* 250 steel
Fe-based amorphous 1.3 150 .mu. 100* 400 metal Note) *Power
specification with a gap inserted at a part of a magnetic path.
[0078] As seen from the above Table 4, the inductance component of
this invention has a magnetic flux density equivalent to that of
the inductance component using the amorphous metal and exhibits a
core loss characteristic lower than that of the inductance
component using Sendust. Therefore, the inductance component of
this invention can be used as a very excellent inductance
component. It has been confirmed that, in the inductance component
using the heat-treated core, the permeability and the core loss are
further improved.
EXAMPLE 30
[0079] In an example 30, an inductance component was produced by
the use of a material corresponding to the sample No. 12 in the
example 28. Further, another inductance component was prepared
using a high-frequency core produced by the same alloy powder and
the same production process and heat treated at 500.degree. C. for
0.5 hour in a nitrogen atmosphere. Further, for comparison,
inductance components (including the structure having a gap at a
part of a magnetic path as shown in FIG. 4) were produced by the
use of Sendust, 6.5% silicon steel, and a Fe-based amorphous metal
as core materials, respectively. For those inductance components,
the magnetic flux density (at 1.6.times.10.sup.4 A/m) by d.c.
magnetic characteristics measurement, the d.c. specific resistance
.OMEGA.cm, the permeability for standardization of the inductance
value, and the core loss (20 kHz 0.1 T) were measured. The results
shown in Table 5 were obtained.
5TABLE 5 magnetic flux specific sample density/T at resistance
permeability core loss name 1.6 .times. 10.sup.4 A/M .OMEGA.cm --
20 kHz 0.1 T this invention 1.21 0.5 160 50/mW/cc this invention
1.23 0.4 220 25 (heat treated) MnZn ferrite 0.55 >10.sup.4 100*
9 Sendust 0.65 100 80 100 6.5% silicon 1.0 100 .mu. 100* 250 steel
Fe-based 1.3 150 .mu. 100* 400 amorphous metal
[0080] As seen from the above Table 5, the inductance component of
this invention has a magnetic flux density substantially equivalent
to that of the inductance component using the Fe-based amorphous
metal as a core and yet exhibits a core loss lower than that of the
inductance component using Sendust as a core. Therefore, the
inductance component of this invention has a very excellent
characteristic. It has been confirmed that, in the inductance
component using the heat-treated core, the permeability and the
core loss are further improved and more excellent characteristics
are achieved.
EXAMPLE 31
[0081] In an example 31, an alloy powder having a composition of
Fe.sub.72Si.sub.9B.sub.14.5Nb.sub.3Al.sub.1.0C.sub.0.5 was prepared
by water atomization. Thereafter, the powder thus obtained was
classified into those having a particle size of 45 .mu.m or less.
Then, XRD measurement was carried out to confirm a broad peak
specific to a glass phase.
[0082] Further, thermal analysis by DSC was carried out to measure
a glass transition temperature and a crystallization temperature to
confirm that a supercooled liquid temperature range .DELTA.Tx was
35K. Then, powders obtained by water atomization and having alloy
compositions represented by the following Table 6 were filtered by
a standard sieve into the powders of 20 .mu.m or less. These
powders were mixed at ratios shown in Table 6.
[0083] Further, using the powders thus obtained, a silicone resin
as a binder was mixed in an amount of 1.5% in mass ratio. By the
use of a die with a groove having an outer diameter
.phi..sub.OUT=27 mm.times.an inner diameter .phi..sub.IN=14 mm,
these powders were molded at a room temperature by applying a
pressure of 12 t/cm.sup.2 so that the height was equal to 5 mm.
Thus, various kinds of molded bodies were produced. After molding,
heat treatment was carried out in Ar at 500.degree. C.
[0084] Next, the various kinds of molded bodies thus obtained were
subjected to resin curing. Thereafter, the weight and the size of
each molded body were measured. Then, an appropriate number of
turns of winding was provided to prepare various kinds of
inductance components (having the shape illustrated in FIG. 2).
[0085] Then, for each of the various samples of the inductance
components, the powder filling rate %, the permeability, and the
core loss (20 kHz 0.1 T) were measured. The results shown in Table
6 were obtained.
6TABLE 6 added powder alloy powder filling magnetic sample compo-
ratio rate permeability core loss No. sition (mass %) (vol %) at
100 kHz 20 kHz 0.1 T compara- -- -- 71.9 36 25 kW/m.sup.3 tive
example this invention 1 3% SiFe 5 72.5 39 30 2 " 10 73.1 41 40 3 "
20 73.7 42 60 4 " 30 74.4 43 70 5 " 40 74.9 44 80 6 " 50 75.4 46 90
7 " 60 75.6 46 200 8 sendust 30 73.1 40 80 9 Mo 30 75.4 45 85
permalloy 10 pure iron 30 76.9 50 95 powder
[0086] As seen from Table 6, the inductance component of this
invention is improved in powder filling rate by adding to the
metallic glass powder the soft magnetic powder smaller in particle
size, and is consequently improved in permeability. On the other
hand, if the added amount exceeds 50%, the improving effect is
weakened and the core loss characteristic is significantly
degraded. Therefore, it is understood that the added amount is
preferably 50% or less.
EXAMPLE 32
[0087] In an example 32, alloy powders having a composition of
Fe.sub.73.5-q-rSi.sub.9B.sub.14.5Nb.sub.3C.sub.qAl.sub.r in which
the ratio of q and r were variously changed were prepared by water
atomization. Thus, powders having aspect ratios shown in Table 7
were prepared. Thereafter, the powders thus obtained were
classified into those having a particle size of 45 .mu.m or less.
Then, XRD measurement was carried out to confirm a broad peak
specific to a glass phase. Further, thermal analysis by DSC was
carried out to measure a glass transition temperature and a
crystallization temperature to confirm that a supercooled liquid
temperature range .DELTA.Tx was 35K.
[0088] Further, using the powders thus obtained, a silicone resin
as a binder was mixed in an amount of 3.0% in mass ratio. By the
use of a die with a groove having an outer diameter
.phi..sub.OUT=27 mm.times.an inner diameter .phi..sub.IN=14 mm,
these powders were molded at a room temperature by applying a
pressure of 1.47 GPa (15 t/cm.sup.2) so that the height was equal
to 5 mm. Thus, various kinds of molded bodies were produced. After
molding, heat treatment was carried out in Ar at 500.degree. C.
[0089] Next, the various kinds of molded bodies thus obtained were
subjected to resin curing. Thereafter, the weight and the size of
each molded body were measured. Then, an appropriate number of
turns of winding was provided to prepare various kinds of
inductance components (having the shape illustrated in FIG. 2).
[0090] Then, for each of the various samples of the inductance
components, the powder filling rate % and the permeability were
measured. The results shown in Table 7 were obtained.
7 TABLE 7 powder magnetic filling permeability aspect rate at 100
kHz sample ratio (vol %) at 0 (Oe) at 50 (Oe)
Fe.sub.71.3Si.sub.9B.sub.14.5Nb.sub.3- C.sub.0.7Al.sub.1.5 1.1 70
26 24 Fe.sub.71.5Si.sub.9B.sub.14.5Nb.su- b.3C.sub.0.5Al.sub.1.5
1.3 68 29 24 Fe.sub.72.0Si.sub.9B.sub.14.5Nb-
.sub.3C.sub.0.5Al.sub.1.0 1.5 67 32 25
Fe.sub.73.2Si.sub.9B.sub.14.- 5Nb.sub.3C.sub.0.1Al.sub.0.2 1.9 66
37 25 Fe.sub.73.3Si.sub.9B.sub.- 14.5Nb.sub.3C.sub.0.05Al.sub.0.15
2.2 65 42 23
[0091] As seen from Table 7, the inductance component of this
invention is improved in permeability by increasing the aspect
ratio of the metallic glass powder. On the other hand, if the
aspect ratio exceeds 2.0, the initial permeability is high but the
permeability under d.c. superposition is degraded. Therefore, it is
understood that the aspect ratio of the powder is preferably 2 or
less.
EXAMPLE 33
[0092] At first, as a powder preparing step, materials were weighed
so as to obtain the composition of
Fe.sub.72.0Si.sub.9B.sub.14.5Nb.sub.3C.sub.0- .5Al.sub.1.0. By the
use of the materials, soft magnetic alloy fine powders different in
average diameter were prepared by high-pressure water
atomization.
[0093] Next, as a molded body preparing step, the alloy powders
thus obtained were filtered by various types of standard sieves to
prepare powders shown in Table 8. Thereafter, a silicone resin as a
binder was mixed in an amount of 3% in mass ratio. Then, by the use
of a die of 10 mm.times.10 mm, each powder was molded, together
with a winding coil having an outer diameter of .phi..sub.OUT=8, an
inner diameter .phi..sub.IN=4 mm and a height of 2 mm and arranged
so that, after molding, the winding coil is positioned at an exact
center of a molded body, by applying a pressure of 490 MPa at a
room temperature so that the height was equal to 4 mm. Thus, molded
bodies were formed.
[0094] Next, resin curing was performed at 150.degree. C. As to a
sample No. 5, another sample was also prepared by heat treating the
inductance component at 500.degree. C. for 0.5 Hr in nitrogen.
[0095] Next, for each of the various samples of the inductance
components, the inductance and the resistance were measured at
various frequencies by the use of an LCR meter. From the
measurements, the inductance value at 1 MHz, the peak frequency of
Q, and the peak value of Q were obtained. The results shown in
Table 8 were obtained.
[0096] Next, for the same samples of the inductance components, a
power conversion efficiency was measured by the use of an
evaluation kit for a typical DC/DC converter. The results are as
follows. The measurement condition was an input of 12 V, an output
of 5 V, a drive frequency of 300 kHz, and an output current of 1
A.
8TABLE 8 power mesh average conver- particle diameter L (.mu.H)
peak peak sion sample size (D50) at frequency value effi- No. .mu.m
.mu.m 1 MHz of Q of Q ciency compara- 45 33 0.58 300 kHz 32 79.6%
tive example 1 1 " 28 0.61 600 kHz 44 83.1 2 " 23 0.64 800 kHz 47
83.7 3 " 18 0.67 1.5 MHz 62 85.2 4 " 15 0.65 2.5 MHz 67 85.4 5 " 10
0.63 3.5 MHz 77 85.7 5 (heat " " 0.70 3.0 MHz 82 87.3 treated
compara- 63 28 0.67 400 kHz 35 79.8 tive example 2
[0097] As seen from Table 8, in the inductance component of this
invention, when the mesh particle size was 45 .mu.m or less and the
average diameter was 30 .mu.m or less, the peak frequency of Q was
500 kHz or more and its value was 40 or more. At that time, the
power conversion efficiency was as excellent as 80% or more. When
the mesh particle size was 45 .mu.m or less and the average
diameter was 20 .mu.m or less, the peak frequency of Q was 1 MHz or
more and its value was 50 or more. At that time, the power
conversion efficiency was as more excellent as 85% or more.
Further, it is understood that, by heat treating the inductance
component, the conversion efficiency is further improved.
[0098] As described above, in the high-frequency core according to
this invention, an alloy composition of
(Fe.sub.1-aCo.sub.a).sub.100-x-y-z-q-r-
(M.sub.1-pM'.sub.p).sub.xT.sub.yB.sub.zC.sub.qAl.sub.r(0<a<0.50,
0<p<0.5, 2 atomic %<x<5 atomic %, 8 atomic %<y<12
atomic %, 12 atomic %<z<17 atomic %, 0.1 atomic %<q<1.0
atomic %, 0.2 atomic %<r<2.0 atomic % and
25<(x+y+z+q+r)<30, M being at least one selected from Zr, Nb,
Ta, Hf, Mo, Ti, V, Cr, and W, M' being at least one selected from
Zn, Sn, and R (R being at least one element selected from rare
earth metals including Y), T being at least one selected from Si
and P) is selected as a soft magnetic metallic glass powder
excellent in economic efficiency. This makes it possible to obtain
the powder excellent in magnetic characteristics, glass forming
performance, and powder filling ability. Further, the powder is
subjected to oxidization or insulating coating and molded by the
use of a die or the like using an appropriate molding method to
obtain a molded body. In this manner, the powder core is prepared.
Therefore, a high-permeability powder core which exhibits excellent
permeability characteristics over a wide band and which is never
known is obtained. As a result, it is possible to economically
produce a high-frequency core of a soft magnetic material having a
high saturation magnetic flux density and a high specific
resistance. Further, an inductance component comprising the
high-frequency core and at least one turn of winding wound
therearound is obtained as an economical and high-performance
product which has never been obtained. Accordingly, this invention
is extremely useful in industrial application.
[0099] In this invention, if the metallic glass powder having a
maximum particle size of 45 .mu.m or less in mesh size and an
average diameter of 30 .mu.m or less, more desirably 20 .mu.m or
less, is used, a powder core having an extremely low loss
characteristic at a high frequency is obtained. An inductance
component comprising the high-frequency core with at least one turn
of winding wound therearound is extremely excellent in Q
characteristic so that the power supply efficiency can be improved.
Thus, this invention is very useful in industrial application.
[0100] Further, in this invention, the metallic glass powder having
a maximum particle size of 45 .mu.m or less in mesh size and an
average diameter of 30 .mu.m or less, more desirably 20 .mu.m or
less, is press-molded with a winding coil embedded in a magnetic
body to form an integral structure. In this event, in addition to
the excellent core characteristics specific to the metallic glass,
heat generation resulting from an electric current flowing through
the winding coil is radiated through the metal magnetic body. By
the synergetic effect thereof, it is possible to obtain an
inductance component increased in rated current for the same shape.
Herein, the temperature of the strain-relieving heat treatment of
the metallic glass powder is lower than a temperature above
600.degree. C. which is believed as an upper limit of the allowable
temperature for a copper wire and a coating material used in the
winding coil. Therefore, by the heat treatment at a temperature not
higher than 600.degree. C., it is possible to obtain a coil
remarkably reduced in loss. Therefore, as the powder forming the
core having an integral structure of the winding coil and the
powder, the alloy composition of this invention is very
suitable.
[0101] As described above, the high-frequency core according to
this invention is economically obtained by the use of the soft
magnetic metallic glass material having a high saturation magnetic
flux density and a high specific resistance. Further, the
inductance component obtained by providing the core with the
winding is excellent in magnetic characteristics in a
high-frequency band as never before. Thus, a high-permeability
powder core low in cost and high in performance as never before can
be produced and is suitably used in a power supply component, such
as a choke coil and a transformer, of various electronic
apparatuses.
[0102] By the use of the high-frequency core obtained by molding
the powder having a fine particle size in this invention, a
higher-performance inductance component at a high frequency can be
produced. Further, in the high-frequency core obtained by molding
the powder having a fine particle size, press-molding may be
carried out with the winding coil embedded in the magnetic body to
form an integral structure. Thus, the inductance component small in
size and adapted to a large current can be produced and is suitably
used as an inductance component such as a choke coil and a
transformer.
* * * * *