JPH05152845A - Microwave oscillator - Google Patents

Abstract

PURPOSE:To inexpensively manufacture the microwave oscillator and to reduce a temperature change in the oscillating frequency by making a casing of a plastic. CONSTITUTION:An oscillation circuit is formed on the surface of a dielectric board 21 and a ring pattern 29 is formed around the circuit. A plastic-made cover 31 on the surface of which a metallic layer 32 is plated is adhered opposite to the ring pattern 99 to enclose the oscillation circuit. Lead wires are led to a rear side through the dielectric board 21, and an earth lead 30 being one of them and the metallic layer 32 are connected to shield the oscillator. A tuning screw 35 is provided to a ceiling of the cover 31 and a gold plating layer 34 to be connected to ground is formed to the rear side of the dielectric board 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oscillator assembly using a dielectric resonator.

[0002]

2. Description of the Related Art Conventionally, this type of oscillator has been disclosed in Japanese Patent Laid-Open No. 62-2.
There was one described in Japanese Patent Publication No. 0991. That is, as shown in FIGS. 4 and 5, a case (1) forming a shield case and a lid (2) of the case (1) are provided, and a dielectric material is provided on a substrate (3). The resonator (4) is attached via the supporting dielectric (5), and strip lines (6) (7) magnetically coupled to the dielectric resonator (4) are formed on the substrate (3). The microwave semiconductor element for oscillation (8) is connected to one end of the strip line (6) and the other strip line (7)
The output terminal (9) was connected to one end of the.
Incidentally, (10) is a power supply terminal for supplying direct current to the microwave semiconductor element (8), and (11) is a mounting screw for mounting and fixing the case.

The magnetic field coupling strength determined by the distance between the dielectric resonator (4) and each strip line (6) (7) and the microwave semiconductor element (8) to the strip line (6)
If the distance to the magnetic field coupling point of the upper dielectric resonator (4) is properly set so as to satisfy the oscillation condition according to the negative resistance characteristic of the semiconductor element (8), the dielectric resonator (4) It oscillates at the resonance frequency of and the oscillation output can be taken out from the output terminal (9). Further, a screw hole is provided in the ceiling part of the case (1) and the tuning screw (12) is screwed in, and the screwing amount is changed to change the distance between the dielectric resonator (4) and the tuning screw (12). The oscillation frequency is finely adjusted by.

By the way, since the microwave oscillator has a resonance frequency as high as 10 to 12 GHz, it is essential to shield the oscillator. Therefore, in the past, the case (1) and the lid (2) were made of a conductive metal such as an iron alloy, and the two were welded and sealed, and both were electrically grounded via the screw (11). Was shielded by doing.

[0005]

However, since the case (1) and the lid (2) forming the housing are made of metal, the cost of the parts is high, and the cost of welding them is also high. Therefore, there is a drawback that the device becomes expensive. In addition, since the coefficient of thermal expansion of metal is large, the variation in the distance between the tuning screw (12) and the dielectric resonator (4) due to the change in the outside air temperature is large (for example, several μ), and therefore the temperature variation in the oscillation frequency is large. It had the drawback of being large.

Further, since the device is fixed by a thick mounting screw (11) which also serves as a ground lead of the housing, holes for the mounting screw (11) in addition to the external connection leads (9, 10) are provided. Need to be separately provided, and there are drawbacks that the process is complicated for assembling the electronic device and the cost is high. Furthermore, since the case (1) and the lid (2) are made of metal, they are bonded by seam welding.
It is necessary to provide an adhesive portion (X in FIG. 4) around the device to keep the welding strength, which has a drawback of hindering downsizing of the device.

[0007]

The present invention has been made in view of the above-mentioned various drawbacks of the related art. A metal film (32) is formed on the surface of a box body made of plastic to form a cover (31), and a strip is formed. The cover (31) is attached to the dielectric substrate (21) on which the lines (22) and (23) are formed so as to seal the strip lines (22) and (23), and the dielectric substrate (2
By constructing a housing by using 1) as a cover of a cover (31), an inexpensive microwave oscillator with a small frequency temperature fluctuation is provided.

[0008]

According to the present invention, the material of the cover (31) is made of plastic or resin, and the dielectric substrate (21) is formed as a part of the housing as it is, so that the unit price of the parts can be reduced and the number of parts can be reduced. Can be reduced.
Further, the plastic material forming the cover (31) is
Since the coefficient of thermal expansion is smaller than that of conventional metal, the variation in the distance between the dielectric resonator (26) and the cover (31) is small.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. 1, 2 and 3 show a module assembly of a microwave oscillator according to the present invention. FIG. 1 is a sectional view taken along the line AA of FIG. 3, and FIG. 2 is a sectional view taken along the line BB of FIG. First, referring to FIGS. 1 and 3, a plate thickness of 1.0 to 2.0 m having a high dielectric constant (εr = 9.7) such as ceramics.
A strip line (22) and a strip line (23) are formed by screen printing on the surface of a dielectric substrate (21) of m, and a microwave semiconductor element (24) such as GaAs MESFET is mounted on a bare chip and one strip line ( 2
Connect to one end of 2) with wire bond. The output terminal (25) is connected to one end of the other strip line (23). A dielectric resonator (26) is attached near the center of the dielectric substrate (21) via a supporting dielectric (27) to form a dielectric substrate (21).
And the strip lines (22) and (23) are magnetically coupled to each other, so that the oscillation circuit including the microwave semiconductor element (24) and the dielectric resonator (26) are interposed via the strip lines (22) and (23). Join. Incidentally, (28) is a power supply terminal for supplying direct-current power to the microwave semiconductor element (24).

The dielectric resonator (26) and the strip line (2
2) An annular pattern (29) is formed by a conductive pattern on the surface of the dielectric substrate (21) surrounding the (23), and the ground lead (30) is connected to a part of the annular pattern (29). It The ground lead (30) also applies the ground potential to the oscillator circuit. Output terminal (25) and power supply terminal (28)
2 is penetrated through the dielectric substrate (21) and led out to the back surface side, and is soldered and fixed to the conductive pattern on the front surface side of the dielectric substrate (21). The ground lead (30) is placed at the opposite position of the output terminal (25) and the power supply terminal (28) in consideration of the stable manufacture of the device at the time of mounting. It is led out to the back surface side of the substrate (21). Moreover, the thickness of the lead is the same as that of the output terminal (25) and the like.

The cover (31) comprises a box body having a thickness of about 1.0 mm, which is obtained by molding an epoxy thermosetting resin in a mold and is formed by electroless plating with a conductive metal such as nickel after the molding. A metal film (32) having a film thickness of several thousand Å to 1.0 μ is formed on the entire surface. Then, the metal film (32) provided in the vicinity of the end face of the cover (31) and the annular pattern (29) of the dielectric substrate (21) are adhered by solder (33) or the like, so that the dielectric substrate (21). The lid is used to seal the oscillation circuit group. Since the ground potential is applied to the annular pattern (29) by the earth lead (30), the annular pattern (2
The metal film (32) of the cover (31) is grounded via 9) to shield the internal oscillation circuit.

Further, by forming a gold plating layer (34) on the back surface of the dielectric substrate (21) and connecting the gold plating layer (34) to the ground lead (30) on the back surface side of the dielectric substrate (21), Completes the shield effect on the dielectric substrate (21) side. The gold plating layer (34) at the lead-out portion of the output terminal (25) and the power supply terminal (28) is partially removed. The gold plating layer (34) provided on the back surface of the dielectric substrate (21) is
When the assembly of the present invention is mounted on a printed circuit board, the gold plating layer (34) and the conductive pattern on the surface of the printed circuit board can be used for strong mounting by facing each other with solder. Each lead is inserted into the through hole of the printed board and soldered.

On the ceiling of the cover (31), a tuning screw (3) is provided at a position corresponding to the dielectric resonator (26).
Equipped with 5). The tuning screw (35) is screwed to a metal pipe-shaped female screw member (36), and the female screw member (36) is integrally formed when the cover (31) is molded. It is fixed. It is desirable that the plate thickness of the cover (31) and the length of the female screw member (36) are the same, but if the length is insufficient due to the screw pitch, as shown in FIG. The female screw member (36) is made to project above. This tuning screw (35) changes the distance between the tuning screw (35) and the dielectric resonator (26) by adjusting the screwing amount of the tuning screw (35) after assembling, and the oscillation frequency of the oscillator is desired. It is provided to adjust to the frequency.

In this embodiment constructed as described above, since the dielectric substrate (21) is a part of the housing, the conventional lid (2) can be omitted. Therefore, the number of parts can be reduced and the cost can be reduced. Further, since the cover (31) is made of plastic such as epoxy resin, the cost of material can be reduced. Further, by providing a metal layer (32) on the surface of the cover (31) and grounding it with the ground lead (30), the oscillation circuit group can be shielded. The gold plating layer (34) formed on the back surface of the dielectric substrate (21) not only helps shield the oscillation circuit but also can be used as an adhesive layer for facing and adhering to the printed circuit board when the device is mounted.

Since plastic has a smaller coefficient of thermal expansion than conventional metal, the cover (31) for fixing the tuning screw (35) is made of plastic, so that the tuning screw (35) and dielectric against the ambient temperature can be reduced. It is possible to suppress fluctuations in the distance from the body resonator (26) and reduce changes in the oscillation frequency with temperature. Further, since the cover (31) and the dielectric substrate (21) are bonded by soldering, the bonding can be performed at a lower temperature than conventional welding, and the end face of the cover (31) is bonded to the surface of the dielectric substrate (21) so as to face each other. Therefore, the peripheral adhesive portion (X in FIG. 4) which is required in the conventional welding is not required, and the lid (2) is not required, which contributes to downsizing of the device.

[0016]

As described above, according to the present invention, the plastic substrate (31) is used, and the dielectric substrate (21) is used.
Since it is a part of the housing, the cost of parts is reduced,
This has the advantage that the device can be manufactured inexpensively. Further, since the cover (31) is made of plastic having a small coefficient of thermal expansion, there is an advantage that fluctuation of the oscillation frequency with respect to ambient temperature can be reduced.

Further, since the structure of the housing is simplified, it has an advantage that it can contribute to the miniaturization of the device, and that it can provide a device that can be easily mounted on a printed circuit board.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining the present invention.

FIG. 2 is a cross-sectional view for explaining the present invention.

FIG. 3 is a plan view for explaining the present invention.

FIG. 4 is a cross-sectional view for explaining a conventional example.

FIG. 5 is a plan view for explaining a conventional example.

[Explanation of symbols]

 (21) Dielectric substrate (25) Output terminal (26) Dielectric resonator (29) Ring pattern (30) Ground lead (31) Cover (32) Metal film (35) Tuning screw

Claims (8)

[Claims] 1. A dielectric substrate having a dielectric resonator, a plurality of strip lines magnetically coupled to the dielectric resonator, and a microwave semiconductor element connected to one of the strip lines. The surface is covered with a conductive film for a shield, and a plastic cover adhered on the dielectric substrate so as to seal the resonant circuit and the semiconductor element, and connected to the strip line, A microwave oscillator, comprising: an external connection lead, which is led out to the back surface so as to penetrate the dielectric substrate. 2. The microwave oscillator according to claim 1, further comprising a ground lead electrically connected to the conductive film of the cover and extended to the back surface so as to penetrate the dielectric substrate. .. 3. The microwave oscillator according to claim 1, wherein the conductive film of the cover is nickel plated. 4. The microwave oscillator according to claim 1, wherein the cover is an epoxy thermosetting resin. 5. The microwave according to claim 1, wherein an annular conductive thin film is formed on the surface of the dielectric substrate, and the conductive film of the cover is soldered to the annular conductive thin film. Oscillator. 6. The microwave oscillator according to claim 1, wherein a metal thin film is formed on the back surface of the dielectric substrate, and the metal thin film is electrically connected to the conductive film of the cover. 7. The microwave oscillator according to claim 1, wherein a tuning screw is provided on a ceiling portion of the cover. 8. The microwave according to claim 7, wherein a metallic female screw member provided with a screw hole is fixed to a ceiling portion of the cover, and the tuning screw is inserted into the female screw member. Oscillator.