JP2000252707A - Irreversible circuit element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a metal-made case used in common with a magnetic circuit for an irreversible circuit element, to realize high performance of the irreversible circuit element and to attain a design with a high degree of freedom. SOLUTION: The irreversible circuit element 1 has a center conductor part 5 consisting of a ferrite 50 and a center conductor 55, a capacitive element 4 connected to the center conductor 55, and a permanent magnet 6 that applies a DC magnetic field to the ferrite 50. The components above are placed in a metal-made lower case 2 and a metal-made upper case 7, which are used in common with a magnetic yoke. The type of the material of the metal-made case 2 and/or 7 is a Fe-Co alloy consisting by weight of 49% Co, 2% V, the balance Fe, 0-0.015% C, 0-0.10% Si and 0-0.15% Mn and with inevitable impurities. Furthermore, the metal-made case is configured with the upper and lower halves, and when an air gap between the center conductor part 5 and the permanent magnet 6 is selected to be a prescribed gap such as 0.3 to 0.5 mm, the upper case 7 to which the permanent magnet 6 is fixed is made of at least an Fe-Co alloy in this irreversible circuit element 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-reciprocal circuit device having an irreversible transmission characteristic with respect to a high-frequency signal, and more particularly to a non-reciprocal circuit device used in a mobile communication system such as a portable telephone. The present invention relates to a non-reciprocal circuit device called a circulator.

[0002]

2. Description of the Related Art Hitherto, non-reciprocal circuit devices such as isolators and circulators have been known as one of transmission / reception circuit components used in microwave bands and UHF bands for mobile phones, automobile phones, and the like. In general, isolators and circulators are used for the purpose of preventing breakage of an amplifier, and have a function of reducing insertion loss in a signal transmission direction and increasing reverse loss in a reverse direction. Hereinafter, in the specification of the present application, an isolator among non-reciprocal circuit devices will be described as an example.

FIG. 1 is an exploded perspective view showing an example of a lumped constant type isolator. The isolator 1 has a metal lower case 2, an earth plate 3, and a ceramic dielectric substrate 4 soldered and arranged, and a central conductor portion 5 is mounted in a through hole 40 at the center of the substrate 4. I have. Center conductor 5
Is a disk-shaped ferrite 50 made of, for example, garnet.
And three center conductors 55, whose ends 56, 57 and 58 intersect at the center of the ferrite at 120 degrees so as to wrap the ferrite 50 in an insulating state. Then, a metal upper case 7 to which a permanent magnet 6 for applying a DC magnetic field to the ferrite core 50 is fixed is disposed on the center conductor portion 5.
And a metal lower case 2 (hereinafter simply referred to as upper and lower cases).
Are assembled by fitting and soldering.

Here, on the upper surface of the substrate 4, electrode patterns 41, 42, 43 constituting a capacitive element are formed by thick-film printing, and each of the center conductors 56, 57 made of a copper band.
And 58 are insulated from each other. And electrode 4
3 is connected to a ground electrode 45 via a dummy resistor 44, and the ground electrode 45 is connected to the ground plate 3 via a through hole 46. On the other hand, the end portion 56 of the central conductor is connected to the electrode 43, and the other central conductors 57 and 58 are drawn out of the gap 70 between the upper case 7 and the lower case 2 to form input / output terminals. It is supposed to. If the dummy resistor is eliminated and an external terminal is attached in the same manner as other center conductors, a circulator is obtained. The connection between the electrode pattern and the end of the center conductor is performed by, for example, soldering.

Incidentally, the upper case and the lower case have a function of mechanically holding and protecting each of the above-mentioned components at a correct position inside thereof. On the other hand, it electromagnetically acts as a yoke constituting a magnetic circuit, and at the same time has a function of suppressing interference between the inside and the outside of the isolator with an electric shielding effect. In this regard, it can be said that this is an important part for efficiently operating the isolator without missing a high-frequency signal and reducing power loss. Conventionally, as a material constituting these upper and lower cases, a metal material mainly composed of iron, specifically, J
Generally, a so-called SPCC material specified in IS-G3141 "Cold rolled steel sheet and steel strip" is used. Was plated with nickel or the like to improve electrical conductivity and aesthetic appearance, and was put to practical use.

[0006]

In recent years, in the field of mobile communication, not limited to isolators, the demand for miniaturization and high performance has been increasing. Higher performance has become an issue. For this reason, further improvement has been required for the conventional upper and lower cases. That is, as the case material, a material having excellent mechanical strength that can contribute to miniaturization in spite of its small thickness, and at the same time, having high magnetic properties and also expected to improve insertion loss because it also serves as a magnetic yoke can be expected. Is desired.

The ideal characteristics of an isolator are that the insertion loss in the signal transmission direction is extremely small and the reverse loss is extremely large as described above.
Many factors can be considered to obtain this characteristic, one of which is to reduce the difference in loss factor between ferrite and permanent magnet, that is, the air gap between the center conductor and permanent magnet, the so-called air layer. Increasing a gap (hereinafter, referred to as a gap) can be cited. Normally, a predetermined range is set based on the specification conditions and the relative relationship between the ferrite and the permanent magnet.However, in practice, this gap is difficult to manage numerically because of dimensional errors and assembly errors of parts. As a result, both the insertion loss and the reverse loss characteristics are not stable, and there is a problem that the characteristics vary depending on the individual isolators. In addition, on the other hand, there is a problem that the design must be made at the expense of the gap, that is, in a direction in which the predetermined range is narrowed, in order to reduce the size.

As described above, the present invention achieves downsizing and high performance of a case constituting an isolator or a circulator, and at the same time, enables a highly flexible design, and as a result, reduces insertion loss and reverse loss. It is an object of the present invention to provide a non-reciprocal circuit device having uniform characteristics.

[0009]

According to the present invention, there is provided a center conductor portion including a ferrite and a center conductor, a capacitor connected to the center conductor, and a permanent magnet for applying a DC magnetic field to the ferrite. In a non-reciprocal circuit device in which these are arranged in a metal case also serving as a magnetic yoke, the metal case is made of a Fe—Co alloy,
o: 40 to 60, V: ≦ 5, a non-reciprocal circuit device formed from an Fe—Co alloy including the balance of Fe and unavoidable impurities. Further, in mass%, Co: 49, V: 2, C: ≦
0.015, Si: ≦ 0.10, Mn: ≦ 0.15, thickness of 100 μm to 20 consisting of balance of Fe and unavoidable impurities
It is preferable to use a cold-rolled material of about 0 μm.

As described above, since the case forming the outer frame of the nonreciprocal circuit element is formed of an Fe--Co alloy having excellent magnetic properties and particularly having a high saturation magnetic flux density, the leakage of magnetic flux from the magnetic circuit is extremely small and the efficiency is low. Good, for example, the magnetic performance does not deteriorate even if the thickness of the plate material is about 70% of the conventional thickness. In addition, this alloy has a necessary and sufficient mechanical strength, and is particularly resistant to external vibrations because of its high vibration absorbing ability and excellent vibration isolation. Therefore, if a non-reciprocal circuit element equivalent to the conventional one is obtained, the size can be reduced.

Further, the present invention has a center conductor portion composed of a ferrite and a center conductor, a capacitor connected to the center conductor, and a permanent magnet for applying a DC magnetic field to the ferrite, and comprising a magnetic yoke. In the non-reciprocal circuit element arranged in a metal case also serving as a, the metal case is formed of a divided case, at least when the air gap between the central conductor portion and the permanent magnet is set within a predetermined gap, The case to which the permanent magnet is fixed is
This is a non-reciprocal circuit device formed from an e-Co alloy. still,
The predetermined gap is desirably about 0.3 to 0.5 mm.

When the case is divided as described above, at least the case on which the permanent magnet is fixed, and the cases on both sides are usually formed of an Fe-Co alloy in order to secure magnetic characteristics. According to this case, as described above, the case thickness can be reduced by about 30% as compared with the conventional case, that is, several tens of μm, so that a nonreciprocal circuit element of the same size (height) can be obtained. The thinner case can be used as a margin for the air gap between the center conductor and the permanent magnet. Therefore, the predetermined gap has a larger value, so that the insertion loss characteristics of the non-reciprocal circuit device can be improved and the variation can be suppressed and stabilized.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, the isolator shown in FIG. 1 is taken as an example, and the description of the internal structure is omitted here. However, since the internal configuration is not particularly limited in the present invention, for example, a chip capacitor can be used for the ceramic substrate, and a chip resistor can be used for the dummy resistor. May be formed on each layer of the laminated substrate by a printed conductor. Although it is practical to divide the metal case into upper and lower parts as shown in the figure, the present invention is not limited to this and may be a box shape or the like.

Further, the surface of the case is made of a metal or alloy containing at least one of silver, copper, gold and aluminum and has an electric resistivity of 5.5 μΩcm or less, preferably 3.0 μΩcm or less.
It is desirable to form a highly conductive metal film having a resistivity of Ωcm, more preferably 1.8 μΩcm or less. The film thickness at this time is 0.5 to 25 μm, preferably 0.5 to 10 μm.
μm, more preferably 1 to 8 μm. Thus, the present invention is effective in reducing the loss of improving the signal transmission efficiency and suppressing the mutual interference with the outside of the element separately from the present invention. Further, on this conductive film, a conductive protective film layer such as nickel or chromium plating of about 0.2 to 2 μm may be formed from abrasion resistance, oxidation resistance and aesthetic factors.

The upper and lower cases 2 and 7 in FIG. 1 are basically formed of an Fe—Co alloy. The composition of the Fe—Co alloy is, specifically, C% by mass.
o: 49, V: 2, C: ≤ 0.015, Si: ≤ 0.1
0, Mn: ≦ 0.15, alloy using balance Fe and inevitable impurities is used. An ultra-thin plate of about 100 μm can be manufactured from this alloy plate material.
At 000, the saturation magnetic flux density can maintain the characteristic of 2.25 Tesla. Here, Co is selected in the range of 40 to 60% from the correlation between the frequency band and the magnetic characteristics, but is preferably around 50%. V is added to improve the cold workability, but on the other hand, it affects the magnetic properties, so V is set to 5% or less, and 2% is desirable for ensuring press workability.

The lower case 2 and the upper case 7 of FIG. 1 are prepared by subjecting the above-mentioned strip material having a thickness of 150 μm manufactured by cold rolling or hot rolling to magnetic annealing and strain relief annealing to improve workability. It was obtained by pressing. The condition of the magnetic annealing is 850 ° C. in hydrogen or in a vacuum.
× 3hr then gradual cooling (100 ~ 2 between 800 ~ 400 ° C)
(Cooling at 00 ° C./hr), and the press formability after strain relief annealing was almost the same as that of the conventional material. From the viewpoint of the magnetic properties after the case is formed, the cold-rolled material is more preferable. In this embodiment, the case thickness is 70 to
Even if it was 90%, the same magnetic properties were obtained, and the mechanical strength was practically comparable.

Next, the air gap between the center conductor and the permanent magnet will be described briefly. FIG. 2 shows an extremely simple schematic diagram of the isolator, in which the conventional case is indicated by a dotted line and the case of the present invention is indicated by a solid line. 8C is a combination of a substrate and a center conductor, etc., 8D is a permanent magnet, 8
A is a lower case, and 8B is an upper case. Here, it is necessary to interpose an air gap g between the center conductor 8C and the permanent magnet 8D in order to stabilize the performance. Conventionally, this gap g is within a predetermined range, for example, about 0.3 to 0.4 mm. Often set to. However, as described above, the gap may not actually fall within this range due to a dimensional error or an assembly error of a part, and the gap is designed to be reduced in order to reduce the size. Therefore, the characteristics vary. In this regard, according to the present invention, since the upper case and / or the lower case are appropriately made thin and have excellent magnetic properties as shown in the above-described embodiment, approximately tens of μm of the reduced thickness is used as an increase in the gap g. Thus, the gap g 'can be formed and the upper limit can be approached even within a predetermined gap. Therefore, if a nonreciprocal circuit device having the same height is obtained, the performance such as the insertion loss characteristic can be improved and stabilized.

Table 1 shows examples of the present invention and comparative examples. The material of the case used in each example was the above-mentioned composition, and the comparative example was a conventional material (SPCC material having a thickness of 0.2 mm). Then, a comparative test was performed on these with respect to the overall height of the isolator and the insertion loss.
2 and Comparative Example 1 showed an effect on miniaturization, and Example 3 and Comparative Example 2 showed an effect on high performance. As a result, according to the present invention, the size (height) can be reduced without changing the performance, and the performance can be improved and stabilized because the air gap can be set larger. I understand.

[0019]

[Table 1]

[0020]

According to the present invention, in a non-reciprocal circuit device such as an isolator or a circulator, a metal case that is used as a strength component and a magnetic circuit is formed from an Fe-Co alloy, thereby reducing the case thickness. However, the magnetic flux leakage in the magnetic circuit is suppressed, and the strength such as anti-vibration performance is sufficient. As a result, if a nonreciprocal circuit device having the same performance is obtained, the size can be reduced. On the other hand, since the air gap between the center conductor and the permanent magnet can be made larger as the case thickness becomes thinner, the degree of freedom in setting the predetermined gap increases. As a result, if non-reciprocal circuit devices of the same size are obtained, the performance can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of the structure of an isolator according to the present invention.

FIG. 2 is a schematic diagram illustrating an embodiment of the isolator according to the present invention.

[Explanation of symbols]

 1: Isolator 2: Metal lower case 3: Earth plate 4: Ceramic substrate (dielectric substrate) 5: Central conductor 6: Permanent magnet 7: Metal upper case 8A: Lower case 8B: Upper case 8C: Center 8D: permanent magnet g, g ': air gap (gap between air layers)

Claims (4)

[Claims] 1. A ferrite and a central conductor comprising a central conductor, a capacitive element connected to the central conductor, and a permanent magnet for applying a DC magnetic field to the ferrite, which are made of metal which also serves as a magnetic yoke. In a non-reciprocal circuit device arranged in a case, the metal case is made of Fe-C
A non-reciprocal circuit device formed from an o-alloy. 2. A metal conductor which has a central conductor portion composed of a ferrite and a central conductor, a capacitive element connected to the central conductor, and a permanent magnet for applying a DC magnetic field to the ferrite, and these are also used as a magnetic yoke. In the non-reciprocal circuit device arranged in the case, the metal case is formed of a divided case, and when the air gap between the central conductor and the permanent magnet is set within a predetermined gap, at least the permanent magnet is fixed. A non-reciprocal circuit device, wherein the case is formed from an Fe-Co alloy. 3. The Fe—Co constituting the metal case.
3. The non-reciprocal circuit device according to claim 1, wherein the alloy comprises, by mass%, Co: 40 to 60, V: ≦ 5, the balance being Fe and unavoidable impurities. 4. 4. An Fe—Co component constituting the metal case.
The alloy is expressed by mass%: Co: 49, V: 2, C: ≦ 0.0
15, Si: ≦ 0.10, Mn: ≦ 0.15, balance Fe
3. The non-reciprocal circuit device according to claim 1, comprising an unavoidable impurity.