JPS60146501A - High frequency circuit - Google Patents

Abstract

PURPOSE:To simplify the manufacture by forming a ground conductor with a thick film circuit and a transmission line with a thin film circuit in a microwave strip circuit so as to form the ground conductor to the inner wall of a through- hole of a substrate. CONSTITUTION:The through-hole 25 is formed in advance to the dielectric substrate 21 made of alumina ceramic. The ground conductor 22 is formed on the dielectric substrate 21 by printing and baking the thick film paste. The thick film paste is adhered to the inner wall 27 around the through-hole 25 by decreasing the pressure through the evacuation of air from the surface at printing. Vapor-deposition or sputtering is applied to a face forming the transmission line 23 so as to form the thin film layer 28. Since a metallic layer is given to the inside of the through-hole 25, electric connection is attained between a connection conductor 29 and the thin film layer 28.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a high frequency amplification circuit, a high frequency oscillation circuit, and
relates to the structure of a high frequency circuit that constitutes a high frequency modulation/demodulation circuit, etc.

(Prior Art) Generally, when realizing a high frequency circuit used in a high frequency band including a microwave band, a microwave strip circuit based on a distributed constant circuit is used.

The microwave strip circuit is, for example, formed on an alumina ceramic substrate, as shown in the partial perspective view of FIG. In FIG. 1, 11 is a dielectric substrate, 12 is a ground conductor, 13 is a transmission line, 14 is a transistor, 15 is a through hole, and 16 is a metal ribbon. In FIG. 1, the microwave strip circuit includes a dielectric substrate 11 formed of an alumina ceramic substrate, metal coatings applied to both the front and back surfaces, and a ground conductor 2 on the back surface as an external conductor.
The conductor on the surface is configured as a transmission line 13. The transmission conductor 13 and the ground conductor 12 are thin film circuits formed by depositing gold or steel by vapor deposition, some by sputtering, and further employing a photolithography process.

In the high-frequency amplification circuit, it is necessary to ground the emitter of the transistor 14 due to the circuit configuration. Therefore, a through hole 15 is provided in the dielectric substrate 11, and a surface conductor forming a transmission line 13 and a ground conductor 12 are formed. In this case, it is difficult to connect the front conductor and the back conductor using a thin film circuit.
A metal ribbon 16 made of gold was used to read both sides. However, the process of making the connection using the metal ribbon 16 has a disadvantage in that workability is extremely poor, and a high frequency circuit equipped with such a connection conductor is expensive.

Further, since the transmission line 13 requires a precise pattern shape, it is difficult to configure the transmission line 13 using anything other than a thin film circuit. Furthermore, since the ground conductor 12 on the back side has a simple shape, there is a drawback that if a thin film circuit is applied, the manufacturing process becomes complicated and expensive.

(Object of the Invention) The object of the present invention is to form a transmission line on the surface of a dielectric substrate using a thin film conductor based on a vapor deposition process, a sputtering process, and a photolithographic process, and then print it while reducing pressure from the surface of the dielectric substrate. By firing this and forming a grounding conductor on the top and back surfaces of the dielectric substrate, and forming a connecting conductor on the inner wall of the through hole of the dielectric substrate, the above drawbacks are eliminated and a high frequency circuit that can be manufactured at a low cost. Our goal is to provide the following.

(Structure of the Invention) The high frequency circuit according to the present invention is formed into a planar shape with through holes on a dielectric substrate used for high frequency bands including microwave bands, and has a transmission line and a ground conductor. , and a connecting conductor.

The transmission line is formed on the surface of the dielectric substrate by thin film technology based on sputtering, vapor deposition, and photolithography.

The ground conductor is formed on the back surface of the dielectric substrate by thick film technology based on printing and firing processes.

The connection conductor was manufactured by using a vacuum process to reduce the pressure from the surface of the dielectric substrate during printing in addition to the printing and firing process, and the above transmission line formed on the surface of the dielectric substrate, This is formed on the inner wall of a through hole bored between the ground conductor and the ground conductor formed on the back surface.

(Example) Next, the present invention will be described in detail with reference to the drawings.

FIG. 2 is a sectional view showing an example of the manufacturing process of an embodiment of the high frequency circuit according to the present invention. In FIG. 2, 21 is a dielectric substrate, 22 is a ground conductor, 23 is a transmission line, 25 is a through hole, 27 is an inner wall of the through hole, 2B is a deposited layer, and 29 is a connecting conductor.

Figure 2 (1) shows an alumina ceramic dielectric substrate 21.
FIG. 3 is a sectional view in which a through hole 25 is pre-drilled. The through holes 25 can be formed during the process of molding the dielectric, or can be easily drilled using a laser beam after the dielectric is molded. FIG. 2(2) is a sectional view showing the process of forming the ground conductor 22 on the dielectric substrate 21, printing and firing a thick film paste. If air is drawn from the surface during printing to reduce the pressure, the thick film paste can be easily attached to the inner wall 27 around the through hole 25, and the connection conductor 29 can be formed.

FIG. 2(3) is a cross-sectional view showing a pattern in which a thin film layer 28 is formed by vapor deposition or sputtering on the surface on which the transmission line 23 is to be formed. At this time, since the metal layer wraps around inside the through hole 25, an electrical connection can be established between the connection conductor 29 and the thin film layer 28. Figure 2 (4) is
3 is a cross-sectional view showing a process of forming a transmission line 23 by subjecting a thin film layer to a photolithography process. FIG.

Therefore, according to the present invention, a ground conductor with a simple shape is formed by a thick film circuit, a transmission line with a complex and precise shape is formed by a thin film circuit, and a connecting conductor between the ground conductor and the transmission line is formed with a thick film circuit. This can be easily realized using membrane technology.

(Effects of the Invention) As explained above, according to the present invention, a transmission line is formed on the surface of a dielectric substrate by a thin film conductor based on a sputtering process and a photolithography process, and further, a transmission line is formed on the surface of the dielectric substrate. The manufacturing process is simplified by printing under reduced pressure and firing to form a ground conductor on the back side of the dielectric substrate and a connecting conductor on the inner wall of the through hole in the dielectric substrate. This has the effect of lowering the price of stable products.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view of a high frequency circuit according to the prior art. FIG. 2 is a sectional view showing an example of the manufacturing process of an embodiment of the high frequency circuit according to the present invention. 11.21... Dielectric substrate 12.22... Ground conductor 13.23... Transmission line 14... Transistor 15.25... Through hole 16
...Metal ribbon 27...Inner wall of through hole 28...
Vapor deposited layer 29... Connecting conductor patent applicant: Nippon Boki Co., Ltd. Representative Patent attorney: Hisashi Inoro

Claims (1)

[Claims] In a high frequency circuit formed in a planar shape with through holes on a dielectric substrate for use in high frequency bands including microwave bands, the dielectric substrate is formed using thin film technology based on sputtering, vapor deposition, and photolithographic processes. a transmission line formed on the surface of the dielectric substrate, and a ground conductor formed on the back surface of the dielectric substrate by thick film technology based on printing and firing processes;
In addition to the printing and firing steps, by using a vacuum step in which the pressure is reduced from the surface of the dielectric substrate during the printing period, the transmission line formed on the front surface of the dielectric substrate and the transmission line formed on the back surface of the dielectric substrate are formed. A high frequency circuit comprising: a connecting conductor bored between the ground conductor and a connecting conductor formed on the inner wall of the through hole.