JPH06252612A - Printed circuit board incorporating strip line - Google Patents

Abstract

PURPOSE:To devise a printed circuit board in which interference between strip lines hardly takes place. CONSTITUTION:The printed circuit board 1 incorporating a strip line is mainly made up of a board main body 2 made of an electric insulation material and plural sets of strip circuits 3 formed on the base main body 2. Each strip circuit 3 is mainly made up of a couple of ground patterns 5a,5b arranged in parallel and a strip line 6 arranged between the patterns 5a,5b. The ground patterns 5a,5b of each strip circuit 3 are separately formed respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board, and more particularly to a strip-line built-in circuit board.

[0002]

2. Description of the Related Art In order to meet the demand for miniaturization of communication devices such as mobile phones, there is a demand for higher density of circuit boards arranged inside the communication devices. As a circuit board for fulfilling such a demand, there is known a circuit board in which a filter, a resonator, and the like are configured by a striped resonant line, and the striped resonant line is built therein. A general circuit board of this kind includes a board made of an electrically insulating material, a plurality of sets of strip lines arranged in the board, and a ground pattern arranged in the board and facing each other while being insulated from the strip lines. Is mainly equipped with. The ground pattern is formed in a wide area so that it can be used as a common ground pattern for a plurality of sets of strip lines.

[0003]

In the conventional strip line built-in circuit board, since a plurality of sets of strip lines share one ground pattern, a circuit constituted by any one of the strip lines and the ground pattern. The electrical vibration generated at the time may bring noise to a circuit constituted by another strip line and the ground pattern.

Further, the strip line and the ground pattern are usually as thin as about 10 to 20 μm and have a large wiring resistance. For this reason, the electric resistance of the circuit becomes large, and it is difficult to obtain a large Q value required for realizing a narrow band filter, for example. If the line width of the strip line is widened, the wiring resistance is reduced, but in this case, high-density wiring in the substrate is hindered.

An object of the first invention is to prevent interference between strip lines. An object of the second invention is to prevent interference between strip lines and to reduce the wiring resistance of the strip lines. An object of the third invention is to reduce the wiring resistance of the strip line.

[0006]

A circuit board with a built-in strip line according to a first aspect of the present invention includes a substrate made of an electrically insulating material, a plurality of sets of strip lines arranged in the substrate, and strips arranged in the substrate. It is provided with a ground pattern which is insulated and faces the line. The ground pattern is divided so as to form a pair with each of the plurality of sets of strip lines.

A strip-line-embedded circuit board according to a second aspect of the present invention is the strip-line-embedded circuit board according to the first aspect of the present invention, wherein the strip line comprises a plurality of strip lines laminated at intervals. Electrically connected to each other. A strip-line-embedded circuit board according to a third aspect of the present invention includes a substrate made of an electrically insulating material and a plurality of lines laminated at intervals in the substrate, and the plurality of lines are electrically connected to each other. A plurality of sets of strip lines and a ground pattern that is arranged in the substrate and faces the strip lines while being insulated from each other.

[0008]

In the circuit board with a built-in strip line according to the first aspect of the present invention, the ground pattern is divided so as to correspond to each of the plurality of sets of strip lines. Here, since each of the divided ground patterns forms a pair with each strip line, it is electromagnetically induced by the strip line,
The function as a ground pattern is not impaired. Further, even if electrical vibration occurs in a circuit composed of any strip line and its corresponding ground pattern, this vibration causes noise in the circuit composed of the other strip line and its corresponding ground pattern. It is unlikely to have an effect such as.

In the circuit board with a built-in strip line according to the second aspect of the present invention, each strip line is composed of a plurality of lines electrically connected to each other. Therefore, in addition to the function of the first aspect, the electrical resistance value of the strip line is increased. Becomes smaller. Third
In the circuit board with a built-in stripline according to the invention, since the stripline is composed of a plurality of lines electrically connected to each other and laminated, the stripline has a small electric resistance value.

[0010]

1 and 2 show a multilayer circuit board 1 according to an embodiment of the present invention. In the figure, the multilayer circuit board 1 is
It is mainly configured by a plate-shaped substrate body 2, a plurality of sets of strip circuits 3 formed in the substrate body 2, and surface wirings 4 provided on both main surfaces of the substrate body 2.

As shown in FIG. 2, the substrate main body 2 is an integrated sheet 2a, 2b, obtained by laminating, for example, four ceramic green sheets and firing them integrally.
It is composed of 2c and 2d. The ceramic material forming each of the sheets 2a ... 2d is, for example, alumina ceramics, mullite ceramics, aluminum nitride ceramics, or silicon carbide ceramics.

Each strip circuit 3 is of a balanced type mainly composed of a pair of ground patterns 5a and 5b arranged in parallel with each other and a strip line 6 sandwiched therebetween. The ground patterns 5a and 5b are respectively the sheet 2a.
And 2b and between the sheets 2c and 2d, and are separated from the ground patterns 5a and 5b of another strip circuit 3 adjacent to each other. The strip line 6 is
It is arranged between the sheets 2b and 2c, and is formed in a stub shape or a coil shape having a predetermined length. The ground patterns 5a and 5b and the strip line 6 are made of a refractory metal material. As the refractory metal material, for example, tungsten, molybdenum, manganese or the like is used.

The strip circuit 3 described above constitutes a filter resonance circuit by the strip line 6 and the ground patterns 5a and 5b. The surface wirings 4 are formed on both main surfaces of the substrate body 2 in a predetermined high-density pattern.
It is connected to each strip circuit 3 by an internal circuit (not shown) provided therein. In the figure, only a part of the surface wiring 4 is shown, and details are omitted. Like the strip circuit 3, the surface wiring 4 is formed of a refractory metal such as tungsten, molybdenum, or manganese.

Next, a method of manufacturing the circuit board 1 will be described. First, four ceramic green sheets 7a, 7b, 7c, 7d for forming the substrate body 2 are prepared. The thickness of each ceramic green sheet 7a ... 7d is preferably set to 100 to 200 μm. Each ceramic green sheet 7a ... 7d is provided with a through hole (not shown) for forming the above-mentioned internal circuit.

Next, each ceramic green sheet 7a ...
The through hole provided in 7d is filled with the paste made of the above-mentioned high melting point metal material. Also, the ceramic green sheet 7
A ground pattern 5 is provided on each of the upper surfaces of a, 7b and 7c.
A pattern 9a for forming a, a pattern 9b for forming the strip line 6 and a pattern 9c for forming the ground pattern 5b are printed. At the same time, a pattern for forming an internal circuit is also printed. Each pattern can be formed by screen-printing a paste made of the above-mentioned high melting point metal material. The ceramic green sheets 7a, 7b, 7c and the ceramic green sheet 7d on which the above-described patterns are printed are laminated in this order as shown in FIG. When this is baked, a substrate body 2 having a plurality of strip circuits 3 and an internal circuit (not shown) is obtained.

On both main surfaces of the obtained substrate body 2, a paste made of the above-mentioned metal material is printed in a predetermined pattern of the surface wiring 4. Then, in a reducing atmosphere, this is about 1
Baking at a temperature of 600 ° C. As a result, the circuit board 1 having the surface wirings 4 of a predetermined pattern on both main surfaces of the board body 2
Is obtained. As shown in FIG. 2, on the main surface of the circuit board 1 described above, an electronic component 10 such as an IC is provided at a predetermined portion of the surface wiring 4.
Will be implemented. The electronic component 10 is usually fixed by the solder 11.

In the above-described circuit board 1, the strip circuit 3
Since the ground patterns 5a and 5b forming the above are divided from the ground patterns 5a and 5b of the adjacent strip circuits 3, interference between the strip circuits 3 is unlikely to occur. Therefore, each strip circuit 3 is different from the other strip circuits 3
It is less likely to be adversely affected by noise. Further, since each ground pattern 5a, 5b does not need to be formed in a wide area as in the conventional example, it is not necessary to use a large amount of paste at the time of manufacturing and can be formed at low cost.

[Other Embodiments] (a) In the above embodiment, only one layer of the strip line 6 for forming the strip circuit 3 is provided. However, as shown in FIG. 4, the strip lines 6 are spaced apart from each other. The present invention can be implemented in the same manner even when the layers are stacked. In this case, the laminated strip lines 6 and 6 are electrically connected to each other through a through hole or the like not shown.

By laminating the strip lines 6 in this way, the wiring resistance of the strip lines 6 is reduced, so that the Q value of the strip circuit 3 can be increased. In addition, Q
The relationship between the value and the wiring resistance is as follows.

[0020]

[Equation 1]

In the equation, f is the frequency, L is the wiring inductance, and R is the wiring resistance. Although the strip line 6 is formed in two layers in this embodiment, the strip line 6
Can also be formed in multiple layers. (B) In the above-mentioned other embodiment (a), the ground pattern 5a and the ground pattern 5b may be a series of wide-area ground patterns 12a, 12b as shown in FIG. In this case as well, the wiring resistance of the strip line 6 becomes small, so that a high Q value can be realized. (C) In the above embodiment, the case where the balanced strip line is formed in the substrate main body 2 has been described, but the present invention can be similarly applied to the unbalanced strip line.

[0022]

In the circuit board with a built-in strip line according to the first aspect of the present invention, since the ground pattern is divided into a plurality of patterns, interference between the strip lines is unlikely to occur. In the circuit board with a built-in strip line according to the second aspect of the present invention, the ground pattern is divided into a plurality of portions and the strip lines are formed in multiple layers, so that interference between the strip lines does not easily occur and the wiring resistance of the strip lines is small.

In the circuit board with a built-in strip line according to the third aspect of the present invention, since the strip line is formed in multiple layers, the wiring resistance of the strip line is small.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is a partial sectional view taken along the line II-II of FIG.

FIG. 3 is a diagram showing a manufacturing process of the embodiment.

FIG. 4 is a diagram corresponding to FIG. 2 of another embodiment.

FIG. 5 is a diagram corresponding to FIG. 2 of still another embodiment.

[Explanation of symbols]

 1 circuit board 2 board body 3 strip circuit 5a, 5b, 12a, 12b ground pattern 6 microstrip line

Claims (3)

[Claims] 1. A substrate made of an electrically insulating material, a plurality of sets of strip lines arranged in the substrate, and a ground pattern arranged in the substrate and facing each other while being insulated from the strip line. A circuit board with a built-in strip line, wherein the ground pattern is divided so as to form a pair with each of the plurality of sets of strip lines. 2. The circuit board with a built-in strip line according to claim 1, wherein the strip line is composed of a plurality of lines laminated at intervals, and the plurality of lines are electrically connected to each other. 3. A substrate made of an electrically insulating material, and a plurality of sets of strip lines comprising a plurality of lines laminated at intervals in the substrate, and the plurality of lines being electrically connected to each other. A strip line built-in circuit board, comprising: a ground pattern that is disposed in the board and faces the strip line while being insulated from the ground pattern.