JP2656725B2 - Non-reciprocal circuit for microwave integrated circuit and method of manufacturing the same - Google Patents

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 for a microwave integrated circuit (MIC) and a method for manufacturing the same.
In particular, the present invention relates to a nonreciprocal circuit for MIC having a structure in which a bonded microstrip line is formed on a ferrite plate, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A conventional non-reciprocal circuit for an MIC of this type includes:
Construct a bonded microstrip line on a ferrite plate,
A magnet is arranged near the joint of the joined microstrip line, and a bias magnetic field is applied to the ferrite plate by the magnet. This non-reciprocal circuit for MIC is generally used by fixing the ground conductor of the bonded microstrip line directly or via a metal plate to a metal housing.
The ground conductor is electrically and mechanically connected to the metal plate or the metal housing by soldering, and the metal plate is screwed to the metal housing. This non-reciprocal circuit for MIC is often used by being dropped into a preceding, intermediate or final stage of another hybrid integrated circuit or monolithic integrated circuit.

In this type of non-reciprocal circuit for MIC, the ferrite plate may be constituted by a single substrate, but the saturation magnetization value differs only at the junction for widening the band and reducing the loss. In some cases, a circular ferrite plate is used (for example, Patent Application Publication: Hei 1-19281, Published Patent Publications: 60-4307, 57-64903).

However, in these nonreciprocal circuits for MIC, cracks in the ferrite plate and cutting of the conductor film occur due to the difference between the coefficient of linear expansion of the ferrite plate and the coefficient of linear expansion of the conductor film of the bonded microstrip line. There is a problem that the
No. 22601 is disclosed. In this technique, by interposing titanium between the ferrite plate and the conductor film of the bonded microstrip line, breakage / deformation of the conductor film and cracking of the ferrite plate are prevented.

[0005]

SUMMARY OF THE INVENTION The above-mentioned conventional MIC
The non-reciprocal circuit has a complicated structure such as adding titanium as disclosed in Japanese Patent Application Laid-Open No. Hei 3-22601 when the flatness of the ferrite plate or the metal plate is poor. There is a problem that the ferrite plate is liable to crack due to an assembly stress at the time of assembling.

Further, when the non-reciprocal circuit for MIC is used in a place where the temperature changes drastically, a stress is generated between the ferrite plate and the metal housing due to a difference between a linear expansion coefficient of the ferrite plate and a linear expansion coefficient of the metal housing. There is a problem that a crack may be generated in the ferrite plate having a low strength.

[0007]

A nonreciprocal circuit for a microwave integrated circuit according to the present invention is provided near a ferrite plate, a junction microstrip line formed on the ferrite plate, and a junction of the junction microstrip line. In a non-reciprocal circuit for a microwave integrated circuit having a magnet that applies a bias magnetic field to the ferrite plate, the ferrite plate is a small piece of a ferrite plate having a periphery that is linear and whose adjacent surfaces are bonded to each other with an adhesive. It has a configuration that is an aggregate.

[0008] One of the non-reciprocal circuits for a microwave integrated circuit may have a configuration in which the ferrite plate piece has a substantially square peripheral shape at least at the center of the ferrite plate.

Further, in the method of manufacturing a nonreciprocal circuit for a microwave integrated circuit according to the present invention, a ferrite plate dividing step of dividing a ferrite plate into ferrite plate small pieces having a linear periphery, and the ferrite plate small pieces are divided. A bonding ferrite plate manufacturing process for forming a bonding ferrite plate restored to the original shape of the ferrite plate by bonding at a surface, a bonding microstrip line forming process for forming a bonding microstrip line on the bonding ferrite plate, At least a magnet assembling step of installing a magnet for applying a bias magnetic field to the plate near the joint of the joined microstrip line.

One of the methods for manufacturing the non-reciprocal circuit for a microwave integrated circuit includes a step of dividing the ferrite plate into small ferrite plate pieces having a substantially square peripheral shape at least at a central portion thereof. Can be taken.

[0011]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a view showing the structure of an embodiment of the present invention, FIG. 1 (a) is a perspective view showing a main part of an isolator,
(B) is a plan view of the bonded ferrite substrate 10 used for the isolator of (a).

In this isolator, a bonded ferrite substrate 10 which mainly produces irreversible characteristics with respect to a microwave signal includes a bonded ferrite plate 1 made of a ferrimagnetic material.
Is a microstrip line in which a ground conductor 3 is arranged over the entire back surface and a strip conductor 2 is arranged on the front surface. The strip conductor 2 has connection terminals 2 a, 2 b and 2 c which are connection terminals to another circuit, for example, an MIC circuit, provided near different sides of the bonded ferrite plate 1. The strip conductors 2 extending from these connection ends 2a, 2b and 2c respectively are connected to a joint (joint) of the joint ferrite plate 1.
Since they are coupled by 2d, the bonded ferrite substrate 10 is also called a bonded microstrip line. Here, connection end 2
b is connected to a chip resistor 6 for absorbing a microwave signal, and this chip resistor 6 is further connected to an open conductor 2e which is an open end of the microwave signal at an open end 2f. The shape and area of the joint 2d follow the operating frequency of the isolator.

In this isolator, a spacer 4 which is a low-loss dielectric such as Teflon and a magnet 5 are sequentially stacked in a direction perpendicular to the surface of the joint 2d of the joint ferrite substrate 10. The magnet 5 applies a bias magnetic field to the bonded ferrite plate 1 and causes irreversibility in this isolator. If the chip resistor 6 is not connected to the connection end 2b and this terminal 2b is used as a connection terminal to another circuit, the circuit in FIG. 1 becomes a circulator.

The isolator or circulator shown in FIG. 1A (hereinafter referred to as a nonreciprocal circuit when these two are not distinguished) is generally formed by connecting the ground conductor 3 of the bonded ferrite substrate 10 directly or through a metal plate such as brass to an aluminum alloy. It is used by fixing to a metal housing (not shown) such as The ground conductor 3 is electrically and mechanically connected to the metal plate or the metal housing by soldering, and the metal plate is often screwed to the metal housing.

FIG. 2 shows a bonded ferrite substrate 10 of this embodiment.
FIG. 4 is a view for explaining a method of manufacturing the bonded ferrite plate 1 used in the method.

The joint ferrite plate 1 is an aggregate of ferrite plate pieces 1 _ij (i is an integer of 1 to m, j is an integer of 1 to n, m + n ≧ 3) whose periphery is linear. The surfaces are joined with an adhesive 7. The joined ferrite plate 1 in this figure has 16 ferrite plate pieces 1 _ij (that is, m =
n = 4). As the adhesive 7, an adhesive having high softness, for example, an epoxy resin or a polymer-based thermoplastic adhesive (for example, trade name: Stystic, sold by Techno Alpha Co., Ltd.) or the like can be used, but the elastic coefficient is small. The use of polymeric thermoplastic adhesives is recommended.

Here, the ferrite plate piece 1 _{ij is set} to a frequency of 6
When embodied for an isolator in the GHz band, this ferrite plate piece 1 _ij has a side of about 4 mm and a thickness of about 1 mm.
And the material is Y-Al-based YIG (for example, trade name: NEGAT, manufactured by Tohoku Metal Industry Co., Ltd.). Each of these 16 ferrite plate pieces 1 _ij is bonded in a square shape with an adhesive 7 to produce a bonded ferrite plate 1. Note that the ferrite plate pieces 1 _ij are made of the same ferrite plate, that is, cut into a square ferrite plate having a side of about 16 mm and a thickness of about 1 mm with a diamond cutter or the like, and thus have a uniform thickness. Is convenient.

[0019] (adhesive layer) The thickness of the adhesive 7 are primarily linear expansion coefficient of the ferrite plate pieces 1 _ij, Young's modulus and flexural strength and Young's modulus and linear expansion coefficient of the metal plate equipped with the The determination is made in consideration of the temperature, the environmental temperature, and the characteristic deterioration of the non-reciprocal circuit due to the presence of the adhesive 7. In other words, the thickness of the adhesive 7 is at least such that various mechanical stresses (stresses) applied to the respective ferrite plate pieces 1 _ij due to the difference in the material from the metal plate can be absorbed by the buffer effect of the soft material. In addition, the deterioration of the characteristics of the nonreciprocal circuit is set to an acceptable level. Under the above conditions, the preferable thickness of the adhesive 7 is 1/20 (0.05) of the thickness of the ferrite plate piece 1 _ij.
mm) to 3/10 (0.3 mm).

[0020] As described above, when the junction ferrite plate 1 constituting an aggregate of ferrite plate pieces 1 _ij, stress applied to the junction ferrite plate 1 is substantially equal to the stress applied to each respective ferrite plate pieces 1 _ij, In the specific example, about 1/16 (about 1 /
m ² ). As a result, the bonded ferrite plate 1
Cracking possibility is significantly decreased, this embodiment can prevent the breaking electrical and mechanical deterioration of the characteristics of an isolator or a circulator according to cracking and bonding microstrip line junction ferrite plate 1 Note that ferrite plate piece 1 _ij It is convenient for manufacturing such as division from a ferrite plate having a large area if the peripheral shape is a straight line of a triangle or a rectangle.

Next, referring again to FIG. 1, a bonded ferrite substrate 10 is formed by connecting a strip conductor 2 (2a to 2f) and a ground conductor 3 to a bonded ferrite plate 1 by using a thick film, a thin film, a thin plate or the like mainly composed of a metal. It consists of. These conductors 2
And 3 is most preferably a thick film baking configuration.
For the thick film, a silver conductor containing silver as a main component, for example, trade name: Silver Conductor 6160 (manufactured by DuPont, USA) can be used. This thick film can also be baked on the surface of the adhesive 7. The possibility of the conductors 2 and 3 being broken at points (surfaces) of the adhesive 7 due to expansion and contraction of the adhesive 7 can be reinforced by bonding of a gold wire or a gold ribbon.

As described above, the bonded ferrite substrate 1
0, that is, after the bonded microstrip line is formed on the bonded ferrite plate 1, the substrate 10, the spacer 4, the magnet 5, the chip resistor 6, the metal plate and the like are assembled to form a non-MIC Complete the reversible circuit.

[0023]

As described above, according to the present invention, a microstrip line is formed on a ferrite plate, which is an aggregate of small ferrite plates, the periphery of which is linear and whose adjacent surfaces are bonded with an adhesive. Even if the bonded micro-clip line and the metal plate on which it is mounted are subjected to stress caused by a change in the environmental temperature due to assembly, even if the adhesive absorbs the stress, the circuit breaks the ferrite plate and breaks the bonded micro-strip line. Has the effect of preventing deterioration of the electrical and mechanical characteristics.

Further, in the manufacturing method of the present invention, the ferrite plate is divided into small ferrite plate pieces whose periphery is linear, and the ferrite plate pieces are joined at the divided surfaces to restore the original shape of the ferrite plate. Make a joint ferrite plate,
Since the bonded microstrip line is formed on the bonded ferrite plate, the same effect as described above can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of one embodiment of the present invention;
(A) is a perspective view showing a main part of the isolator, and (b) is a bonded ferrite substrate 10 used for the isolator of (a).
FIG.

FIG. 2 is a diagram illustrating a method of manufacturing a bonded ferrite plate 1 used for a bonded ferrite substrate 10 of the present embodiment.

[Explanation of symbols]

REFERENCE _{SIGNS LIST} 1 bonded ferrite plate 1 ₁₁ to 1 _mn ferrite plate small piece 2 strip conductor 2 a to 2 c connection end 2 d joint 2 e open conductor 2 f open end 3 ground conductor 4 spacer 5 magnet 6 chip resistor 7 adhesive

Claims (5)

(57) [Claims] 1. A microwave integrated circuit comprising: a ferrite plate; a junction microstrip line formed on the ferrite plate; and a magnet installed near a junction of the junction microstrip line and applying a bias magnetic field to the ferrite plate. In a non-reciprocal circuit for a circuit, the ferrite plate is an aggregate of small pieces of a ferrite plate in which the periphery is linear and the adjacent surfaces are bonded to each other with an adhesive. . 2. The non-reciprocal circuit for a microwave integrated circuit according to claim 1, wherein said ferrite plate piece has a substantially square peripheral shape at least at a central portion of said ferrite plate. 3. The non-reciprocal circuit for a microwave integrated circuit according to claim 2, wherein the thickness of the adhesive is 1/20 to 3/10 of the thickness of the ferrite plate piece. 4. A ferrite plate dividing step of dividing the ferrite plate into small ferrite plate pieces whose periphery is linear, and joining the ferrite plate pieces to the original shape of the ferrite plate by joining the small pieces on the divided surfaces. A joining ferrite plate manufacturing process for forming a ferrite plate, a joining microstrip line forming process for forming a joining microstrip line on the joining ferrite plate, and joining a magnet for applying a bias magnetic field to the joining ferrite plate with the joining microstrip line. A method for manufacturing a non-reciprocal circuit for a microwave integrated circuit, comprising at least a magnet assembling step of installing a magnet near a part. 5. The microwave integrated circuit according to claim 4, wherein the step of dividing the ferrite plate is a step of dividing the ferrite plate into small pieces of a ferrite plate having a substantially square peripheral shape at least at a central portion thereof. Manufacturing method for non-reciprocal circuit.