JP2003297641A - Electronic component for communications equipment superior in thdf characteristic, and its thdf reducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic component for communications equipment which is superior in a THDF characteristic by making a distortion of output waveform to an input wave small, and to provide a method for easily reducing the THDF characteristic. <P>SOLUTION: The electronic component is provided with a magnetic core with leg, forming an external leg and an internal leg, a magnetic core matched with the magnetic core with the leg, and a winding arranged in the internal leg. Center line average roughness Ra of the matched face of the magnetic core with the leg and the magnetic core is 1.2 μm or smaller. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device electronic component used for a transmission transformer and a filter of a communication device for xDSL, and particularly, a THD having a small waveform distortion generated when a signal passes through a magnetic core. _{The present} invention relates to an electronic component for communication equipment having excellent _F characteristics and a THD _F characteristic reducing method thereof.

[0002]

2. Description of the Related Art Conventionally, Mn-Zn type ferrite having a high magnetic permeability has been used for electronic components for communication equipment such as various transformers, filters and xDSL modems. Is required to have a high magnetic permeability and to have a small waveform distortion when a communication signal passes through an electronic component for communication equipment.

[0003]

SUMMARY OF THE INVENTION ADSL (Asymmetric Metric Dig) especially for high-speed and large-capacity communication
In the magnetic core used in the communication device for xDSL represented by ital Subscriber Line),
Since the distortion of the signal waveform that occurs when the signal passes causes an increase in the error rate during information transmission, it is necessary to further reduce the waveform distortion when the signal is output. Improvements in magnetic core characteristics are required.

For example, the distortion of the output waveform that occurs when a signal passes through the magnetic core is caused by the fact that the output fundamental wave contains a harmonic component centered on the third harmonic of the input fundamental wave. It is considered that this is due to the non-linearity / hysteresis curve characteristics of the magnetic field H and the magnetic flux density B. Practically, the linearity is improved by providing a gap in the magnetic core for the distortion of the output waveform and reducing the effective magnetic permeability.
It is currently used as a communication transformer.
However, such a method has not been able to substantially improve the linearity of the BH loop such as reduction of coercive force, and has a problem that a load of increasing the number of windings is required to obtain a required inductance. Therefore, it has been necessary to further reduce the distortion by improving the ferrite core itself used in the communication device for xDSL.

The present invention has been discovered as a result of intensive studies for solving the above problems, and it is an electronic component for communication equipment which has a small distortion of an output waveform with respect to an input wave and is excellent in THD _F characteristics, and THD easily. _An object is to provide a method of reducing the _F characteristic.

[0006]

According to a first aspect of the present invention, there is provided a legged magnetic core having an outer leg and an inner leg, a magnetic core abutting the legged magnetic core, and a winding disposed on the inner leg. , The center line average roughness Ra of the abutting surface of the magnetic core with legs and the magnetic core
Is 1.2 μm or less, which is an electronic component for communication equipment excellent in THD _F characteristics. In the present invention, it is preferable that the THD _F characteristic is −100 dB or less at an applied magnetic flux density of 50 mT, a frequency of 10 kHz and a temperature of 25 ° C. It is more preferable to use the legged magnetic core and a ferrite material having an initial magnetic permeability μi of 3,000 or more at a temperature of 25 ° C. of the magnetic core. If the initial magnetic permeability is less than 3,000, the loss due to the increase in the number of windings increases, which is not preferable. A second aspect of the present invention is a communication electronic component including a legged magnetic core having an outer leg and an inner leg, a magnetic core that abuts the legged magnetic core, and a winding disposed on the inner leg, wherein the leg is provided. Centerline average roughness R of the magnetic core and the abutting surface of the magnetic core
THD of electronic parts for communication equipment with a of 1.2 μm or less
_{This is an F} characteristic reduction method.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

The THD _F characteristic used as an index indicating the distortion amount of the output waveform in the present invention will be described. TH
D (Total Harmonic Distorti
on total harmonic distortion) is the ratio of the harmonic component Vh (V) to the fundamental wave Vb (V) and is given by the following equation. THD = 20 × LOG ₁₀ (Vh / Vb) [dB] where μa is the amplitude permeability. A value THD / μa obtained by dividing the ratio of harmonic components by the amplitude permeability μa is obtained by the following equation. THD / μa = 20 × LOG ₁₀ ((Vh / Vb) / μ
a) [dB] The value obtained by dividing the THD value by μa is, for example, Pr.
ocedingsof The Eight Int
international Conference on
This is because, as described in Ferrite, 509, 2000, the evaluation peculiar to the material is performed by excluding the influence of the μa change due to the gap formation or the like on THD. In the present invention, in order to further eliminate the influence of factors such as the number of windings, circuit resistance, and inductance, the following Distortion
of Transformer Coeffie
nt (DTC) was used.

[0009]

[Equation 1]

The THD _F characteristic obtained by the above DTC and THD / μa and obtained by the following equation was used as an index of the magnetic core characteristic. This makes it possible to evaluate the magnetic core characteristics while eliminating the influence of the shape and specifications of the actual product as much as possible. THD _F = THD / μa + 20 × LOG ₁₀ (1 / DT
C) [dB] Here, it is shown that the smaller the THD _F characteristic, the smaller the distortion amount of the output waveform. The frequency used by ADSL is 2
Although it is 0 kHz to 1.1 MHz, the audio analyzer used for the measurement of the THD covers only a part of the low frequency side of the frequency range, and sufficient accuracy may not be obtained even in this range. In the present invention, the THD measurement frequency is conveniently set to 10 kHz.
Evaluated as.

Although the value of the THD _F characteristic increases as the applied magnetic flux density increases, it is set to 50 mT in the present invention from the level of practical use. That is, since the value of the THD _F characteristic differs depending on the measurement frequency and the magnetic flux density and is not unique, the THD _F characteristic in the present invention uses the value under the above-mentioned measurement conditions and is used as a reference for magnetic core evaluation.

The THD _F characteristics of the present invention were evaluated at room temperature (25 ° C.). THD _F characteristic is -1 under the measurement conditions of frequency 10 kHz and applied magnetic flux density 50 mT.
The inventors have found in research that the error rate of information transmission in an actual device can be improved to a practically sufficient level if it is at most 00 dB, and this has been found in THD.
The threshold value was used as a threshold for judging the quality of the _F characteristic.

The magnetic core material of the electronic component for communication equipment of the present invention is not particularly limited as long as it has a μi of 3,000 or more, but it is naturally desired that the magnetic core material itself has a small THD _F characteristic. As the magnetic core material, for example, in a ferrite material having a magnetic permeability of about 8,000 to 15,000, its main component composition is 52.0 to _{5 in} terms of Fe ₂ O _3.
54.0 mol%, more preferably 52.0 to 53.0 mol%, 22.0 to 25.0 mol% in terms of ZnO, and the balance is preferably manganese oxide. The reason for limiting the main component range as described above is as follows. By changing the ratio of the main components Fe ₂ O ₃ , ZnO and manganese oxide, the Curie temperature (Tc) and the so-called secondary peak temperature (Ts) at which the initial permeability μi exhibits a maximum can be controlled. In the invention, the THD _F characteristic, which is used as an index of waveform distortion, can also be controlled in temperature change by the above principal component ratio. That is, the temperature change of the THD _F characteristic is linked with the temperature change of μi, and the secondary peak temperature (T
It becomes a minimum in s). When the THD _F characteristic exceeds the secondary peak temperature, the THD _F characteristic increases as the temperature rises, and then decreases again toward the Curie temperature (Tc). This Ts and Tc
The greater the temperature difference between Ts and Tc, the more T
The increase in HD _F is large. For example, magnetic permeability 8,000-
For ferrite materials of about 15,000, 0 ° C-8
In order to obtain stable THD _F characteristics in a practical temperature range of 5 ° C, it is necessary to control Ts and Tc within a certain range, preferably Ts is -20 ° C to 50 ° C and Tc is 90 to 140. ℃, more preferably Ts is 0 ℃ ~ 4
It is preferable that 0 ° C. and Tc are 100 ° C. to 130 ° C. When Fe ₂ O ₃ is less than 52.0 mol%, Ts shifts to the high temperature side, and as a result, the THD _F characteristic at a low temperature increases remarkably, and when it exceeds 54.0 mol%, Ts shifts to the low temperature side. As a result, the increase of the THD _F characteristic between Ts and Tc becomes large. More preferably 52.0
It is possible to obtain smaller THD _F characteristics in a conventional temperature range of 0 ° C. to 85 ° C. by a ～53.0 mol%.

Further, ZnO is limited to the above range because
When ZnO is less than 22.0 mol%, Tc shifts to the high temperature side, resulting in a large increase in THD _F characteristic between Ts and Tc.
This is because c shifts to the low temperature side and becomes equal to or lower than the upper limit of the practical temperature, and it cannot be practically used.

The Mn-Zn ferrite used in the present invention contains 0 to 0.3 wt% of C, calculated as CaO, as a subcomponent.
It is preferable to contain a. Note that CaO generally has the effect of increasing the electrical resistance of the grain boundaries and reducing the loss by adding it. On the other hand, the coercive force in the measure loop measured by applying a sufficient magnetic field increases, and the increase in the coercive force causes a decrease in the linearity of the BH loop and an increase in hysteresis loss. However, in a communication device for xDSL, for example, a modem for ADSL, a so-called laser with a small applied magnetic field is used.
It has been found that Hc is decreased by addition of CaO at 50 mT, which is used in the low range and is considered to be in the range of the minor loop, and the linearity of the BH loop is improved. It was. The reason why CaO is limited to the above range is that the THD _F characteristic is lowered by adding CaO and the distortion of the waveform can be reduced, but the effect of CaO gradually increases as the content of CaO increases. When it is saturated, especially when it exceeds 0.3 wt%, the structure of the sintered body becomes non-uniform, the initial permeability decreases greatly, and THD
_{This is because} the value of the _F characteristic also deteriorates. Therefore, CaO is preferably 0 to 0.3 wt%, and more preferably 0.0
It is from 05 wt% to 0.15 wt%.

Further, the Mn-Zn-based blower used in the present invention
It has a B value from the viewpoint of improving the initial permeability and reducing core loss.
i_TwoO_Three0 to 0.03 wt% in conversion, SiO_TwoConverted to 0
~ 0.02wt%, Nb_TwoO₅0 to 0.05 wt in conversion
% Bi, Si, Nb is preferably contained. Bi
_TwoO_ThreeIs limited to this range by Bi_TwoO_ThreeIs grainy
Promotes length and contributes to improvement of initial permeability, but 0.05w
If t% is exceeded, grain growth will be remarkable and THD_FValue of characteristic
Because it becomes larger. Therefore Bi_TwoO _ThreeIs 0
It is preferably 0.05 wt%, more preferably 0
Is about 0.035 wt%.

Further, SiO ₂ is limited to the above range because SiO ₂ contributes to increase the electrical resistance of the grain boundary to reduce loss and improve the relative loss coefficient tan δ / μi, but the addition amount is 0.02 wt%. If it exceeds, abnormal grain growth occurs during sintering and T
This is because the HD _F becomes large. Therefore, SiO ₂ is preferably 0 to 0.02 wt%, more preferably 0 to
It is 0.01 wt%.

Also, Nb_TwoO₅Was limited to the above range
Is Nb_TwoO₅Is the sinterability improvement / relative loss coefficient tan δ /
It has the effect of improving μi, but is different when it exceeds 0.05 wt%.
Constant grain growth resulting in THD_FCharacteristic becomes significantly large
This is because. Therefore Nb _TwoO₅Is 0 to 0.05 wt
%, More preferably 0 to 0.03 wt%.
It As described above, for electronic parts for communication equipment of the present invention
The above-mentioned subcomponents in magnetic core materials are mainly THD_FSpecial
Property, initial magnetic permeability μi, relative loss coefficient, etc.
It is preferable to control the content for the purpose of improving. Na
In the present invention, components other than the above main component and subcomponents
It does not mean that the content is not denied, but the above main elements are
In addition, components other than the minor components can be included.

An electronic component for communication equipment according to an embodiment of the present invention will be specifically described below. As core material constituting the electronic component communication _{equipment, Fe 2 O 3, ZnO,} Mn
O is Fe ₂ O ₃ 52.3 mol% and ZnO, respectively.
The mixture was weighed and mixed so as to be 23.0 mol% and 24.7 mol% MnO, and this was calcinated at 850 ° C. for 2 hours. To this, 0.035 wt% of Bi ₂ O ₃ and SiO ₂
0.002 wt%, Nb ₂ O ₅ 0.01 wt%, C
0.01 wt% of aCO ₃ was contained and pulverized with a wet ball mill for 5 hours. A binder is added to these, the mixture is granulated with a spray dryer, compression molded, and sintered at 1300 ° C. for 5 hours in a nitrogen atmosphere in which the oxygen concentration is controlled to obtain the E-shaped magnetic core 1 shown in FIG. The EP magnetic core 1 shown in FIG. 4 was used. Then, the abutting surface a of the magnetic core was ground using grindstones having different grain sizes, and processed so that the centerline average roughness Ra of the abutting surface was 0.4 μm to 1.2 μm. Further, in order to adjust the inductance by practically providing a gap to the inner leg 2, one side of the E-shaped magnetic core 1 shown in FIG.
A gap of 0.05 mm is formed on one side of the EP magnetic core 1 shown in FIG. In the present invention, the presence / absence of a gap is not particularly limited, and the absolute value of THD _F does not change due to the gap. next,
A coil bobbin 5 having a winding wound therein is incorporated into the inner leg 2 of the E-shaped magnetic core, and further, the coil bobbin 5 is butted against the E-shaped magnetic core.
Incorporating another E-shaped magnetic core formed in the same manner, the case 20
It was arranged and fixed at 0, and was provided with the equivalent circuit shown in FIG. 6 to provide a transformer for communication equipment having the appearance shown in the perspective view of FIG. Similarly, an EP type magnetic core was used to form a transformer for communication equipment as shown in a perspective view in FIG. These transformers for communication equipment are used, for example, in a xDSL modem, which is arranged between a computer and a splitter for separating a voice signal and a digital signal in a data transmission line. The machine transformer is used for line modulation between an LSI including a digital modulation / demodulation or control circuit and a telephone line.

The THD _F characteristics at 25 ° C. of the obtained transformer for communication equipment were measured. The measurement circuit is shown in FIG. The number of windings is N1 on the primary side (input side) and N2 on the secondary side (output side), and THD is measured by an audio analyzer manufactured by Audio Precision (System Two).
Using a measuring frequency of 10 kHz, measuring magnetic flux density of 50
The evaluation condition was mT. The center line average roughness Ra was evaluated using the Surfcom 550AD manufactured by Tokyo Seimitsu Co., Ltd. for the surface roughness of the abutting surface a of the magnetic core, with the cutoff value set to 0.8 mm. The evaluation results are shown in FIG.
Table 2 shows the measurement conditions.

[0021]

[Table 1]

[0022]

[Table 2]

As is clear from FIG. 1, the THD _F characteristic decreases as the center line average roughness of the abutting surfaces decreases, and when Ra is 1.25 μm or less, an excellent THD _F characteristic of -100 dB or less can be obtained. It was

[0024]

According to the present invention, the THD _F characteristic can be easily improved by controlling the surface accuracy of the abutting surfaces of the magnetic cores, regardless of the magnetic core material forming the magnetic cores. As a result, a small distortion of the output waveform relative to the input wave, and electronic parts for communication equipment with excellent THD _F characteristics, it was possible to provide a method for easily reducing the THD _F characteristics. In this embodiment, the magnetic core material itself was excellent in THD _F characteristics, be other magnetic core materials that do not exhibit superiority in THD _F characteristics without changes to the effects of the present invention, in other words if even a bad core material somewhat THD _F characteristics can be easily improved THD _F characteristic by controlling the surface accuracy of the abutting surfaces of the magnetic core.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a center line average roughness and THD _F of a magnetic core according to an example of the present invention.

FIG. 2 is a perspective view showing a shape example of a magnetic core used in the present invention.

FIG. 3 is a perspective view of an electronic component for communication equipment according to an embodiment of the present invention.

FIG. 4 is a perspective view showing another example of the shape of the magnetic core used in the present invention.

FIG. 5 is a perspective view of another electronic component for communication device according to an embodiment of the present invention.

FIG. 6 is an equivalent circuit of an electronic component for communication device according to an embodiment of the present invention.

FIG. 7 is a THD measurement and evaluation circuit diagram.

Claims (4)

[Claims] 1. A legged magnetic core formed with an outer leg and an inner leg, a magnetic core that abuts on the legged magnetic core, and a winding disposed on the inner leg, and the abutment of the legged magnetic core and the magnetic core. A centerline average roughness Ra of the surface is 1.2 μm or less, which is an electronic component for communication equipment excellent in THD _F characteristics. 2. The THD _F characteristic has an applied magnetic flux density of 50 m.
-100d at T, frequency 10 kHz, temperature 25 ° C
It is B or less, The THD of Claim 1 characterized by the above-mentioned.
Electronic components for communication equipment with excellent _F characteristics. 3. A temperature of the magnetic core with legs and the magnetic core of 25 ° C.
3. An electronic component for communication equipment having excellent THD _F characteristics according to claim 1 or 2, characterized in that a ferrite magnetic material having an initial permeability μi of 3,000 or more is used. 4. A communication electronic component comprising a legged magnetic core having outer and inner legs formed therein, a magnetic core abutting against the legged magnetic core, and a winding disposed on the inner leg, wherein the legged magnetic core is provided. A method for reducing THD _F characteristics of an electronic component for a communication device, characterized in that a centerline average roughness Ra of a magnetic core and a surface where the magnetic core is abutted with each other is 1.2 μm or less.