JPH05243819A - Strip line and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a strip line of constitution in which formation of a cavity between the center conductor and a dielectric, which deteriorates the characteristic, is prevented, and to obtain its manufacturing method. CONSTITUTION:The strip line consists of the center conductor 1 and a dielectric 2 in which this conductor is sintered integrally in the inside, and also, expansion coefficients of the center conductor 1 and the dielectric 2 are different from each other. In the center conductor 1, a cavity 6 formed by thermal decomposition, etc., at the time when carbon or organic matter is calcined is provided. The strip line having a cavity in the center conductor is manufactured by a process for forming a conductor which becomes a part of the center conductor on a dielectric layer, a process for forming carbon or organic matter in narrower width than that of the conductor concerned on the conductor, a process for further forming a conductor on the conductor so as to cover carbon or organic matter, a process for further stratifying a dielectric on the conductor and the dielectric 2, and a process for calcining them and forming the carbon or organic matter layer to the cavity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a triplate type stripline for forming a resonator or transmission line for an ultra high frequency wave, that is, a central conductor is integrally formed by sintering in a dielectric and both surfaces of the dielectric are formed. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a super high frequency strip line having a ground plane formed therein and a manufacturing method thereof.

[0002]

2. Description of the Related Art In a resonator and a transmission line used for a voltage controlled oscillator, a filter, etc. of a mobile communication device for a very high frequency where a communication signal covers a high frequency region, particularly 250 MHz to several GHz, FIG. ), A central conductor 1 is integrally formed in a dielectric 2 by sintering, and a triplate-type stripline in which a ground plane 3 connected to a ground is formed on both surfaces of the dielectric 2 is used. However, it is preferable in that the signal is not leaked to the outside and the influence of noise from the outside is reduced. 3B is an equivalent circuit of FIG. 3A, in which the end portion a of the center conductor 1 is used as an external connection terminal, and the other end of the center conductor 1 is connected to the ground plane 3 by the through hole 4. 1 forms the inductance L component of (B), and forms the capacitance C component between the central conductor 1 and the ground plane 3.

[0003]

In the conventional strip line described above, for example, a central conductor 1 made of silver is applied by a printing method or the like onto a green sheet made of a dielectric material containing alumina or the like as a main material. Overlaid with a raw sheet of dielectric,
Further, the ground plane 3 is overlaid and pressed and sintered, but since the expansion coefficient of the central conductor 1 made of silver is larger than that of the dielectric 2 such as alumina, the temperature change in the firing step causes the temperature change in FIG. As shown, a void 5 is formed between the center conductor 1 and the dielectric 2, and since this void 5 is an air layer, the permittivity is 1 and the permittivity 6 to 10 of the permittivity 2 is compared. Therefore, there is a problem in that desired characteristics cannot be obtained. The formation of such voids 5 is prevented by adding palladium to silver as the central conductor 1 to reduce the expansion coefficient, but the addition of this palladium has a resistivity lower than that of silver. Since it is large, there is a drawback that the loss becomes large and desired characteristics are difficult to obtain.

In view of the above problems, it is an object of the present invention to provide a stripline and a method of manufacturing the same, which is configured to prevent the formation of voids between the central conductor and the dielectric.

[0005]

According to the present invention, there is provided a strip line comprising a center conductor and a dielectric body obtained by integrally sintering the center conductor, wherein the center conductor and the dielectric body have different expansion coefficients. The central conductor has voids formed by thermal decomposition or the like during firing of carbon or an organic substance. Further, the method for manufacturing a stop line according to the present invention, a step of forming a conductor which is a part of the central conductor on the dielectric layer, and a step of forming carbon or an organic substance on the conductor in a narrower width than the conductor, A step of further forming a conductor on the conductor so as to cover the carbon or the organic material, a step of further superposing a dielectric material on the conductor and the dielectric material, and firing these to form the carbon or organic material layer as voids. And a step of performing.

[0006]

Since the strip line of the present invention has the above-mentioned structure, the voids in the central conductor have a stress absorbing action at the time of thermal expansion and contraction in the firing step, and the voids between the central conductor and the dielectric are prevented. It

[0007]

1 is a cross-sectional view of a stripline according to the present invention. In the figure, reference numeral 1 is a central conductor made of silver or the like, 2 is a dielectric body having a low loss at high frequencies, such as an alumina-based main material integrally formed by sintering the central conductor 1, and 3 is silver. It is a ground plane composed of etc.
6 is a void formed in the central conductor 1 along its longitudinal direction.

FIG. 2 is a manufacturing process chart of this embodiment. First, as shown in FIG. 2A, a conductor 1a made of 100% silver is formed on a dielectric substrate 2a made of a green sheet by a printing method. Next, as shown in (B), a void-forming material 7 made of a substance that is thermally decomposed and vaporized by high-temperature firing, such as an organic substance such as carbon or polyethylene resin, is formed on the conductor 1a to be narrower than the conductor 1a. It is formed by the printing method. Next, as shown in (C), another conductor 1b is formed by a printing method in the same manner as described above so as to overlap the conductor 1a so as to cover the void forming material 7. Next, as shown in (D), a dielectric substrate 2b made of a green sheet is further stacked thereon, and as shown in (E), the ground planes 3 are formed on both upper and lower surfaces.
a, 3b, and after press-bonding the whole with a press, for example, 9
Baking is performed at 00 ° C to 920 ° C.

In this firing step, the void-forming material 7 made of carbon or an organic substance is burnt out to form the voids 6 shown in FIG. Void 6 in this central conductor 1
By the presence of the above, the stress during firing is relieved, and the void 5 shown in FIG. 4 is not generated between the central conductor 1 and the dielectric 2. The thickness of the dielectric 2 after firing is 0.5 mm to 2.0.
mm, the thickness of the central conductor 1 is set to be about 10 μm to 20 μm, and the size of the void 6 is set to a value such that the stress relaxation action is performed when the central conductor 1 thermally expands and contracts. Further, when the gas pressure generated by the void-forming material 7 made of carbon or the like becomes a high pressure that cannot be enclosed in the sintered body, the end portion of the material 7 made of carbon or the like is connected to the center conductor 1.
It may be formed so as to be exposed at the end surface of the above, and the generated gas may leak from the end portion.

Although a single triplate substrate has been described in the above embodiments, a plurality of triplates may be formed in the horizontal direction (in-plane) or may be formed by stacking them in the vertical direction. It goes without saying that it can also be applied to a multi-layered triplate.

[0011]

According to the present invention, the voids provided in the center conductor alleviate the stress generated during firing and prevent the formation of voids between the center conductor and the dielectric. As a result, the presence of the air gap between the central conductor and the dielectric reduces the dielectric constant, and it becomes unnecessary to use a material conductor having a large resistance value such as Ag mixed with Pd, thereby improving the performance of the strip line. Can be done and P
There is an effect that cost reduction can be achieved by reducing d.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a strip line according to the present invention.

FIG. 2 is a manufacturing process diagram of the strip line of FIG.

3A is a perspective view of a conventional stripline, and FIG. 3B is an equivalent circuit diagram thereof.

FIG. 4 is a cross-sectional view showing a void generated in a conventional stripline.

[Explanation of symbols]

 1 central conductor 1a, 1b conductor 2 dielectrics 2a, 2b dielectric substrate 3 ground plane 4 through hole 5 void 6 void 7 void forming material

Claims (3)

[Claims] 1. A strip line comprising a center conductor and a dielectric body integrally sintered therein, wherein the center conductor and the dielectric body have different expansion coefficients, and a void is provided in the center conductor. Characteristic strip line. 2. The strip line according to claim 1, wherein the voids are formed by thermal decomposition during firing of carbon or an organic material. 3. A step of forming a conductor to be a part of a central conductor on a dielectric layer, a step of forming carbon or an organic substance on the conductor in a width narrower than that of the conductor, and a step of covering the carbon or organic substance. A step of further forming a conductor on the conductor, a step of further laminating a dielectric material on the conductor and the dielectric material, and a step of firing these to make the carbon or organic material layer voids. Characteristic stripline manufacturing method.