JPH05102708A - Wiring board for high frequency circuit - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To provide a wiring board for a high-frequency circuit, which is easy to achieve a light, thin, short, and small size and which reduces or eliminates unnecessary electromagnetic coupling between opposite ends of a transmission line. .. [Structure] Microstrip line structure transmission line 2 having a discontinuous portion formed on one main surface of an insulating substrate body 1
The opposite ends of the discontinuous portions of the transmission lines 2a, 2b are grounded by grounding both ends of the second grounding conductor layer 3a that conducts to the grounding conductor layer 3 between the opposite ends of the discontinuous portions of a and 2b. The grounding conductor layer 3 on the other main surface side in a region substantially corresponding to the space is selectively removed. The odd mode electromagnetic coupling between the ends of the transmission lines 2a and 2b facing each other is reduced. Further, when both ends of the second grounding conductor layer 3a are grounded, this action is further enhanced, and in the configuration in which the grounding conductor layer 3 on the back surface side is selectively removed, even mode electromagnetic coupling is also reduced. At the same time, it is possible to suppress a decrease in impedance between the ends and to effectively cut the coupling due to the waveguide mode.

Description

Detailed Description of the Invention

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency circuit wiring board, and more particularly to a high-frequency circuit wiring board for improving isolation between opposing ends of discontinuous portions of a microstrip line structure transmission line.

[0003]

2. Description of the Related Art As information becomes more sophisticated or the amount of information increases, the frequency of signals also becomes higher. For example, in the field of mobile communication such as mobile phones, high frequency integrated circuit devices in the high frequency (microwave) band are used. It's starting. For the purpose of making the high-frequency integrated circuit device lighter, thinner, shorter, and so on, a plurality of required high-frequency integrated circuits are arranged on the surface of a circuit board made of ceramic, for example.

By the way, a wiring board having the following structure is generally used for the structure of this type of high frequency integrated circuit device. That is, as shown in a cross-sectional view of the main structure of FIG. 6, a microstrip line structure transmission line (hereinafter simply referred to as a transmission line) 2 having a discontinuous portion is formed on one main surface of an insulating substrate body 1. The grounding conductor layer 3 is formed on the other main surface of the insulating substrate body 1. Then, the desired semiconductor element 4 is disposed at one end of the discontinuous portion of the transmission line 2, for example, the end of the transmission line 2a, and the semiconductor element 4 is bonded to the end of the other transmission line 2b by the bonding wire 5. It has been put into practical use by being electrically connected by means such as.

In the structure of the high-frequency circuit, when a wiring system in which both ends of the transmission lines 2a and 2b facing each other are not intended to be capacitively coupled, for example, inductive or non-capacitive elements (passive elements and active elements) are used. ) Is disposed at the end of the transmission line 2a, in order to reduce unnecessary electromagnetic coupling between the opposite ends of the transmission lines 2a, 2b, the distance between the opposite ends of the transmission lines 2a, 2b should be minimized. It is set large.

[0006]

However, as described above, setting the distance between the opposite ends of the transmission lines 2a, 2b as large as possible reduces the wiring density on the surface of the insulating substrate, resulting in a light, thin, short and small structure. In addition to the above, the length of the connecting lead (bonding wire or the like) 5 for connecting the element 4 and the transmission line 2b is also increased, and an increase of unnecessary inductive component is inevitable. Here, when the wiring board is used for a high frequency circuit, the increase or increase of the inductive component has a great influence on the characteristics of the high frequency circuit to be constructed, and therefore an effective avoidance measure (solution) is desired. In other words, it can be said that the effective means for solving the above-mentioned problems largely depends on the achievement of the reduction in size, weight and size of the high-frequency integrated circuit device. The present invention has been made in consideration of the above circumstances, and it is easy to achieve lightness, thinness, shortness, and minimization or elimination of unnecessary electromagnetic coupling between opposite ends of a transmission line, and always exhibits an excellent function. An object of the present invention is to provide a high-frequency circuit wiring board suitable for the configuration of a high-frequency circuit device.

[Constitution of Invention]

[0008]

A wiring board for a high frequency circuit according to the present invention is a microstrip line structure transmission having an insulating substrate body and a discontinuous portion formed on one main surface of the insulating substrate body. A wiring board for a high-frequency circuit, comprising a line and a grounding conductor layer formed on the other main surface of the insulating substrate body, between the opposite ends of the discontinuous portion of the microstripline structure transmission line. It is characterized in that a second grounding conductor layer that conducts to the grounding conductor layer is formed, and if necessary, both ends of the second grounding conductor layer are grounded or the transmission line is discontinuous. In this structure, the grounding conductor layer on the back surface side in a region substantially corresponding to the opposite ends of the parts is selectively removed.

[0009]

In the above structure, since the second grounding conductor layer which is electrically connected to the grounding conductor layer on the back surface is formed between the opposite ends of the discontinuous portion of the transmission line, the opposite transmission line ends are formed. Direct or odd-mode electromagnetic coupling between the parts is reduced. In addition, when both ends of the second grounding conductor layer are grounded, this action is further enhanced, and in the structure in which the grounding conductor layer on the back surface side is selectively removed, even mode electromagnetic coupling is reduced. The coupling by the so-called waveguide mode can be effectively cut, especially at high frequencies.

[0010]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a cross-sectional view showing an example of the essential part of a high-frequency circuit wiring board according to the present invention, and FIG. 2 is a plan view of the essential part of the same. FIG. Ceramic substrate 2 (2a, 2b) is a transmission line having a discontinuous portion formed on one main surface of the ceramic substrate 1, and 3 is a ground conductor layer formed on the other main surface of the ceramic substrate 1. Is. However, in this high-frequency circuit wiring board, between the opposite ends of the discontinuous portions of the transmission lines 2a and 2b, the conductive layer for grounding 3 formed on the other main surface is electrically connected through the through hole 3b. The second grounding conductor layer 3a is formed. Further, in the grounding conductor layer 3 formed on the other main surface, substantially corresponding regions between the opposite ends of the discontinuous portions of the transmission lines 2a and 2b are selectively removed (inside the dotted line). Make up the composition.

In other words, the high-frequency circuit wiring board according to the present invention has the same structure as the conventional high-frequency circuit wiring board. First, between the opposite end portions of the discontinuous portions of the transmission lines 2a and 2b, the other main surface is formed. It is characterized in that the second grounding conductor layer 3a is formed so as to be electrically connected to the grounding conductor layer 3 which is formed.
Further, if necessary, the original grounding conductor layer 3 is characterized in that a part of a predetermined region is cut (removed) as described above.

In the high-frequency circuit wiring board of the above configuration example, a grounding conductor layer formed on the other main surface by, for example, a through hole 3b between the opposite ends of the discontinuous portions of the transmission lines 2a and 2b. By forming the second grounding conductor layer 3a that is electrically connected to the transmission line 3, the transmission line 2a that faces and faces relatively close to each other.
Direct or odd mode electromagnetic coupling between the ends of and 2b is easily reduced. FIG. 3 schematically shows this state. The transmission line 2a tip end face and the transmission line 2a which are closely opposed to each other are shown.
Most of the electromagnetic coupling between the ends formed by the tip surface of 2b is made through the second grounding conductor layer 3a formed between the ends (solid line), and direct electromagnetic coupling (dotted line) is made. Greatly reduced.
Thus, the former electromagnetic coupling rapidly decreases as the grounding by the second grounding conductor layer 3a is strengthened. To strengthen the grounding force, it is effective to ground both ends of the second grounding conductor layer 3a.

Further, a part of the grounding conductor layer 3 formed on the other main surface, that is, a region substantially corresponding to between the opposite ends of the discontinuous portions of the transmission lines 2a and 2b is selectively removed ( In the configuration (indicated by the dotted line), even mode electromagnetic coupling between the ends of the transmission lines 2a and 2b is also reduced. FIG. 4 schematically shows this state, and the grounding conductor on the back surface (other surface) of the region corresponding to the end formed by the transmission line 2a front end face and the transmission line 2b front end face that are closely adjacent to each other. Since the layer 3 is missing, the electromagnetic coupling based on the electric field distribution uttered between the transmission line 2a tip surface and the transmission line 2b tip surface and the grounding conductor layer 3 is reduced. At this time, the tip of the transmission line 2a and the transmission line 2a
The node impedance at the tip of 2b (inside the broken line) rises according to the degree of loss of the backside ground conductor layer 3.

The high-frequency circuit wiring board having the above structure can be easily manufactured by, for example, a thick film process or a thin film process without significantly changing the conventional process.

In the above description, the length of the second grounding conductor layer 3a formed on one main surface is longer than the width of the transmission lines 2a and 2b. However, this length is different from the width of the transmission lines 2a and 2b. The transmission lines 2a and 2b may have an opposing positional relationship and the second grounding conductor layer 3a may be formed in the same position as shown in plan view in FIG. 5, for example.

[0017]

As can be seen from the above description, according to the wiring board for a high frequency circuit of the present invention, even when the transmission line end portions of the microstrip line structure are set to be relatively small, It is possible to effectively reduce the electromagnetic coupling due to the even mode, the odd mode, and the waveguide mode between the ends of the transmission line while avoiding the impedance reduction. Moreover, since the second grounding conductor layer formed between the ends of the transmission line has a coplanar arrangement, the impedance of the transmission line end increases due to the selective removal of the grounding conductor layer on the other surface side. It is also possible to easily compensate by adjusting the width of the second grounding conductor layer and adjusting the removal range of the grounding conductor layer on the other surface side. That is, there is an advantage that the node impedance at the end of the transmission line can be set independently of the impedance of the transmission line body.

As described above, since the circuit characteristics can be improved without reducing the density of the transmission line pattern, the high frequency circuit wiring board according to the present invention has many practical advantages in the configuration of the high frequency circuit device. Can be said to bring.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration example of a main part of a high-frequency circuit wiring board according to the present invention.

FIG. 2 is a plan view showing a configuration example of a main part of a high-frequency circuit wiring board according to the present invention.

FIG. 3 is an explanatory view schematically showing a state of odd-mode electromagnetic coupling between transmission line end portions in the high-frequency circuit wiring board according to the present invention.

FIG. 4 is an explanatory view schematically showing a state of even mode electromagnetic coupling to the other surface side between the transmission line ends in the high-frequency circuit wiring board according to the present invention.

FIG. 5 is a plan view showing another configuration example of the main parts of the high-frequency circuit wiring board according to the present invention.

FIG. 6 is a cross-sectional view showing the configuration of a main part of a conventional high-frequency circuit wiring board.

[Explanation of symbols]

1 ... Insulating substrate body 2, 2a, 2b ... Transmission line of microstrip line structure 3 ... Ground conductor layer 3a ...
Second grounding conductor layer 3b ... through hole 4 ... semiconductor element

Claims (3)

[Claims] 1. An insulating substrate body, a microstrip line structure transmission line having a discontinuous portion formed on one main surface of the insulating substrate body, and formed on the other main surface of the insulating substrate body. A wiring board for a high-frequency circuit, comprising: a grounding conductor layer formed between the opposite ends of the discontinuous portion of the microstripline structure transmission line, the second grounding conductor layer being electrically connected to the grounding conductor layer. A wiring board for a high-frequency circuit, characterized in that 2. The high-frequency circuit wiring according to claim 1, wherein both ends of a second grounding conductor layer formed between the opposite ends of the discontinuous portion of the microstripline structure transmission line are grounded. Board. 3. The high frequency wave according to claim 1, wherein the grounding conductor layer is selectively removed in a region on the other main surface side substantially corresponding to between opposed ends of the discontinuous portion of the microstripline structure transmission line. Circuit wiring board.