JPH11266105A - Signal transmission substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain reduction of crosstalks between signal transmission lines by embedding a ground line, which is extended along with the direction of extension in a dielectric substrate part between the signal transmission lines, while exposing it on a first main surface away from the signal transmission lines. SOLUTION: A signal transmission substrate 100 is provided with plural signal transmission lines 12 on a first main surface 10a of a dielectric substrate 10. On this signal transmission substrate 100, the plural signal transmission lines 12 are formed in mutually parallel extended stripe-shaped plane patterns. In addition, a cross-sectional end along with the transmission direction of signals of respective signal transmission lines 12, namely which is vertical to the extending direction of these signal transmission lines 12 is shaped rectangular. On this signal transmission substrate 100, a ground line 14 is embedded at the part of the first main surface 10 between the signal transmission lines 12, while being exposed on the first main surface 10a away from the signal transmission lines 12. Thus, the generation of electric fields between the adjacent signal transmission lines 12 can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission board having a signal transmission line (distributed constant line) for transmitting a high-frequency signal.

[0002]

2. Description of the Related Art An example of the structure of a conventional signal transmission board is disclosed, for example, in Japanese Patent Laid-Open Publication No. 2-271690. This document discloses a configuration of a laser module of an optical transmission module. In this laser module, a laser diode is dice bonded to a submount on a ceramic substrate. Then, a signal transmission line for transmitting a signal to the laser diode (first
And second electrode pins) are formed on the ceramic substrate.

[0003]

When a plurality of laser diodes are provided in one optical transmission module, it is necessary to separately provide a plurality of signal transmission lines for transmitting signals to each laser diode.

However, when individual signals are transmitted in parallel to a plurality of signal transmission lines, an electric field is generated between the signal transmission lines. As a result, this electric field causes crosstalk between the signal transmission lines. In particular, in a signal transmission board of an optical transmission module including a plurality of semiconductor lasers, transmission of a high-frequency signal in a GHz band is performed in parallel by a plurality of signal transmission lines, so that crosstalk between the signal transmission lines becomes a serious problem. .

For this reason, there has been a demand for a signal transmission board capable of reducing crosstalk between a plurality of signal transmission lines.

[0006]

As a result of various studies and experiments, the inventor of the present application has found that if a ground line is provided on a dielectric substrate portion between adjacent signal transmission lines,
The electric field generated by the signal transmitted through the signal transmission line is
It is mainly distributed between the signal transmission line and the nearest ground line, and as a result, by suppressing the generation of an electric field between adjacent signal transmission lines, the crosstalk between the signal transmission lines is reduced. I thought I could do it.

(First Signal Transmission Board) Therefore, according to the first signal transmission board of the present invention, in a signal transmission board having a plurality of signal transmission lines on a first main surface of a dielectric substrate, a signal is transmitted. A ground line extending along a direction in which the signal transmission line extends is embedded in the dielectric substrate portion between the transmission lines so as to be separated from the signal transmission line and exposed on the first main surface. And

As described above, when the ground line embedded in the dielectric substrate between the signal transmission lines (hereinafter, also simply referred to as “substrate”) is provided, the distance between the adjacent signal transmission lines is reduced. It is longer than the distance between the track and the nearest ground track. For this reason, the electric field generated by the high-frequency signal transmitted through the signal transmission line is mainly distributed between the signal transmission line and the nearest ground line. As a result, the generation of an electric field between adjacent signal transmission lines can be suppressed. Therefore, crosstalk between signal transmission lines can be reduced.

In particular, in the first signal transmission board of the present invention, since the ground line is embedded in the board, of the electric fields generated above the first main surface of the board and in the board, respectively, The generated electric field is more effectively distributed between the signal transmission line and the ground line. As a result, it is possible to more effectively suppress the generation of an electric field between adjacent signal transmission lines. Therefore, crosstalk between signal transmission lines can be more effectively reduced.

Further, according to the present invention, since crosstalk between signal transmission lines can be suppressed, a plurality of signal transmission lines can be formed on a dielectric substrate by increasing the distance (pitch) between the signal transmission lines. It can be narrowed and arranged. As a result, it is possible to integrate a circuit including a plurality of signal transmission lines.

[0011] In the first signal transmission board of the present invention, preferably, the exposed portion of the ground line protrudes above the first main surface.

As described above, if the ground line is protruded also on the first main surface, the electric field generated above the first main surface will cause an electric field between the signal transmission line and the protruding portion of the ground line immediately adjacent thereto. Mainly distributed. For this reason, the generation of an electric field distributed between adjacent signal transmission lines can be further suppressed above the first main surface. As a result, crosstalk between signal transmission lines can be more effectively reduced.

(2nd signal transmission board) According to the 2nd signal transmission board of this invention, in the signal transmission board which has the plural signal transmission lines on the 1st main surface of the dielectric board, the signal The cross-sectional shape is V at the first main surface portion between the transmission lines.
The V-shaped groove is provided so as to extend along the extending direction of the signal transmission line, and a ground line is provided on a slope of the V-shaped groove.

As described above, when the ground line is provided in the V-shaped groove in the dielectric substrate between the signal transmission lines, the distance between the adjacent signal transmission lines becomes equal to the distance between the signal transmission line and the nearest ground line. Is longer than the distance. For this reason, the electric field generated by the high-frequency signal transmitted through the signal transmission line is mainly distributed between the signal transmission line and the nearest ground line. As a result, the generation of an electric field between adjacent signal transmission lines can be suppressed. Therefore, crosstalk between signal transmission lines can be reduced.

In particular, in the second signal transmission board of the present invention, since the ground line is provided in the V-shaped groove, the electric field generated in the board is effectively generated between the ground line and the signal transmission line. Distribute. As a result, generation of an electric field between adjacent signal transmission lines can be effectively suppressed. Therefore, crosstalk between signal transmission lines can be more effectively reduced.

In addition, in the second signal transmission line board of the present invention, since the ground line is provided on the slope of the V-shaped groove, the electric field generated above the first main surface of the board is applied to the ground of the slope. The effect of making the distribution easier between the line and the signal transmission line is expected.

Further, according to the present invention, since crosstalk between signal transmission lines can be suppressed, a plurality of signal transmission lines can be formed on a dielectric substrate by increasing the interval (pitch) between the signal transmission lines. It can be narrowed and arranged. As a result, it is possible to integrate a circuit including a plurality of signal transmission lines.

Further, in the second signal transmission board of the present invention, preferably, two V-shaped grooves are provided in the first main surface portion between the signal transmission lines, and the first V-shaped groove between the two V-shaped grooves is provided. It is preferable that the main surface portion includes a protruding portion extending along the extending direction of the V-shaped groove and protruding, and a ground line be provided on a slope of the protruding portion.

As described above, if the ground line is provided on the slope of the protruding portion, the electric field generated above the first main surface will cause the electric field between the signal transmission line and the ground line formed on the protruding portion in the immediate vicinity thereof. Mainly distributed. As a result, above the first main surface,
Generation of an electric field between adjacent signal transmission lines can be more effectively suppressed. For this reason, crosstalk between signal transmission lines can be more effectively reduced.

(Third Signal Transmission Board) According to the third signal transmission board of the present invention, the signal transmission board provided with a plurality of signal transmission lines on the first main surface of the dielectric substrate has the following features. The first main surface portion between the transmission lines is provided with a protruding portion extending along the extending direction of the signal transmission line, and a ground line is provided on a slope of the protruding portion. .

As described above, when the ground line is provided on the slope of the projecting portion of the dielectric substrate between the signal transmission lines, the distance between the adjacent signal transmission lines is equal to the distance between the signal transmission line and the nearest ground line. Longer than the distance between them. Therefore, the electric field generated by the high-frequency signal transmitted through the signal transmission line is:
It is mainly distributed between the signal transmission line and the nearest ground line.
As a result, the generation of an electric field between adjacent signal transmission lines can be suppressed. Therefore, crosstalk between signal transmission lines can be reduced.

In particular, in the third signal transmission board of the present invention, since the ground line is provided on the slope of the projecting portion, the electric field generated in the upper side of the first main surface of the board and in the board respectively includes The electric field generated above one main surface is more effectively distributed between the signal transmission line and the ground line. As a result, it is possible to more effectively suppress the generation of an electric field between adjacent signal transmission lines. Therefore, it is possible to more effectively reduce the crosstalk of the electric field generated above the first main surface between the signal transmission lines.

Further, according to the present invention, it is possible to suppress crosstalk between signal transmission lines, so that a plurality of signal transmission lines can be formed on a dielectric substrate by increasing the interval (pitch) between the signal transmission lines. It can be narrowed and arranged. As a result, it is possible to integrate a circuit including a plurality of signal transmission lines.

Further, in the third signal transmission board of the present invention, preferably, the first signal transmission board and the projecting portion between the signal transmission line and the projecting portion are provided.
A V-shaped groove having a V-shaped cross section is provided in the main surface portion so as to extend along the extending direction of the protruding portion.
It is good to have a grounding track on the slope of the groove.

As described above, if the grounding line is also provided in the V-shaped groove of the dielectric substrate between the signal transmission lines, the electric field in the substrate is reduced by the signal transmission line and the grounding line formed in the V-shaped groove immediately adjacent thereto. More efficiently distributed between For this reason, crosstalk caused by an electric field generated in the substrate can be more effectively reduced.

(Common to the first to third signal transmission boards)
In the first to third signal transmission boards of the present invention, preferably, a portion corresponding to the back side of the signal transmission line in the second main surface of the dielectric substrate, which is the back surface facing the first main surface, It is preferable to provide a back surface groove, and to provide a back surface electrode for grounding in the back surface groove.

As described above, if the back surface electrode is provided in the back surface side groove, an electric field is distributed between the signal transmission line and the back surface electrode. As a result, it is possible to suppress the generation of an electric field between adjacent signal transmission lines in the substrate. Therefore, it is possible to more effectively reduce the crosstalk between the signal transmission lines.

In the first to third signal transmission boards of the present invention, preferably, the back side between the signal transmission lines of the second main surface of the dielectric substrate, which is the back surface facing the first main surface. Is preferably provided with a back surface side groove, and the back surface side groove is provided with a back surface electrode for grounding.

As described above, when the back surface electrode is provided in the back surface side groove, an electric field is distributed between the signal transmission line and the back surface electrode. As a result, it is possible to suppress the generation of an electric field between adjacent signal transmission lines in the substrate. Therefore, it is possible to more effectively reduce the crosstalk between the signal transmission lines.

Further, when the back surface side groove is formed at a portion corresponding to the back side between the signal transmission lines, the distance between the back surface electrode formed in the back surface side groove and the signal transmission line can be increased. Therefore, the influence on the characteristic impedance of the back electrode is small. As a result, the arrangement of the back electrode can be easily designed without considering the characteristic impedance.

(Fourth Signal Transmission Board) According to the fourth signal transmission board of the present invention, in the signal transmission board having a plurality of signal transmission lines on the first main surface of the dielectric substrate, In the second main surface, which is the back surface of the first main surface of the body substrate, a portion corresponding to the back side of the signal transmission line is provided with a back surface side groove, and the back surface side groove is provided with a back surface electrode for grounding. And

As described above, if the back surface electrode is provided in the back surface side groove, an electric field is distributed between the signal transmission line and the back surface electrode. As a result, it is possible to suppress the generation of an electric field between adjacent signal transmission lines in the substrate. For this reason, crosstalk between signal transmission lines can be more effectively reduced.

Further, according to the present invention, it is possible to suppress crosstalk between signal transmission lines, so that a plurality of signal transmission lines can be formed on a dielectric substrate by increasing the interval (pitch) between the signal transmission lines. It can be narrowed and arranged. As a result, it is possible to integrate a circuit including a plurality of signal transmission lines.

(Fifth Signal Transmission Board) According to the fifth signal transmission board of the present invention, in the signal transmission board having a plurality of signal transmission lines on the first main surface of the dielectric substrate, In the second main surface, which is the back surface of the first main surface of the body substrate, a portion corresponding to the back side between the signal transmission lines is provided with a back surface side groove, and the back surface side groove is provided with a back surface electrode for grounding. Features.

As described above, when the back surface electrode is provided in the back surface side groove, an electric field is distributed between the signal transmission line and the back surface electrode. As a result, it is possible to suppress the generation of an electric field between adjacent signal transmission lines in the substrate. For this reason, crosstalk between signal transmission lines can be more effectively reduced.

Further, according to the present invention, it is possible to suppress crosstalk between signal transmission lines, so that a plurality of signal transmission lines can be formed on a dielectric substrate by increasing the interval (pitch) between the signal transmission lines. It can be narrowed and arranged. As a result, it is possible to integrate a circuit including a plurality of signal transmission lines.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a signal transmission board of the present invention will be described below with reference to the drawings. It should be noted that the figures to be referred to show the size of each component so that the present invention can be understood,
It merely shows the shapes and arrangements schematically.
Therefore, the present invention is not limited only to the illustrated example. In the drawings, hatching or the like representing a cross section is partially omitted.

(First Embodiment) In a first embodiment, an example of a first signal transmission board of the present invention will be described with reference to FIG. FIG. 1A is a cross-sectional perspective view of a main part of the signal transmission board according to the first embodiment.
FIG. 1B is a cross-sectional view for explaining the signal transmission board shown in FIG. 1A and its electric field distribution.

As shown in FIG. 1A, the signal transmission substrate 100 of this embodiment has a plurality of signal transmission lines 12 on the first main surface 10a of the dielectric substrate 10. . Here, a ceramic substrate 10 is used as the dielectric substrate 10. The thickness of the ceramic substrate 10 is 1
mm. Further, as a material of the dielectric substrate 10, for example, a resin having a relatively low dielectric constant such as Teflon (trade name) may be used. The width of the signal transmission line 12 is about 0.3 mm. And the signal transmission line 12
Is formed by applying gold plating on a nickel base (not shown) formed on the ceramic substrate 10.

The signal transmission board 10 of this embodiment
In 0, a plurality of signal transmission lines 12 are formed by stripe-shaped plane patterns extending parallel to each other.
FIG. 1 shows three signal transmission lines 12 as representatives. The shape of the cross section perpendicular to the direction in which the signal transmission lines 12 extend along the signal transmission direction, that is, the direction in which the signal transmission lines 12 extend, is rectangular.

In the signal transmission board 100, a ground line 14 separated from the signal transmission line 12 and exposed on the first main surface 10a is embedded in the first main surface 10 between the signal transmission lines 12. . In this example, the ground line 14 has a stripe shape, is provided so as to extend in parallel with the signal transmission line, and is electrically grounded (GND) although not shown. You.

It is desirable that the material of the ground line 14 has a thermal expansion coefficient substantially equal to that of the ceramic substrate 10. In this embodiment, for example, Kovar may be used as the material of the ground line 14. Further, as a material of the ground line 14, for example, silver wax may be used.

The ground line 14 is formed, for example, by forming a groove in a portion between the signal transmission lines 12 on the first main surface 10a of the ceramic substrate 10, and forming a silver wax or metal rod in the groove. Is also good. Further, for example, the through-holes may be formed to be continuous with each other, and the continuous through-holes may be filled with silver wax or another conductive material to form the ground line 14.

Also, in this embodiment, FIG.
And (B), the cross-sectional shape of the ground line 14 is rectangular. The width of the ground line 14 is, for example, about 0.1 mm or more. The depth of the ground line 14 is, for example, about 0.2 mm or more. The distance between the ground line 14 and the signal transmission line 12 is, for example, 0.2
mm or more. Further, the ground line 14 is provided at a position equidistant from the signal transmission lines 12 on both sides.

In designing the specific dimensions of the ground line 14 and the specific distance between the ground line 14 and the signal transmission line 12, the signal transmission line 12 and the
4, the characteristic impedance of the signal transmission board 1
The system is designed so as to match the characteristic impedance (for example, 50Ω) of the system including the optical transmission module, for example, which comprises the optical transmission module 00. When designing the characteristic impedance,
It is preferable to use a conventionally known computer simulation technique.

Next, FIG. 1B is a cross-sectional view of the signal transmission board according to the first embodiment. In FIG. 1B, the distribution of the electric field formed between one signal transmission line 12 provided at the center of the sectional view and the ground lines 14 provided on both sides of the signal transmission line 12 is shown at both ends. This is schematically illustrated by a group of curves having arrows. As shown by the group of curves, the electric field generated by the high-frequency signal transmitted through the signal transmission line 12 is mainly distributed between the signal transmission line 12 and the nearest ground line 14. As a result, generation of an electric field between adjacent signal transmission lines 12 can be suppressed. Therefore, crosstalk between the signal transmission lines 12 can be reduced.

In particular, the signal transmission board 1 of the first embodiment
In 00, since the ground line 14 is embedded in the substrate 10, the electric field generated in the substrate 10 out of the electric fields generated above the first main surface 10a of the substrate 10 and in the substrate 10 is more effective. Distribution between the signal transmission line 12 and the ground line 14. As a result, generation of an electric field between adjacent signal transmission lines 12 can be more effectively suppressed. Therefore, crosstalk between the signal transmission lines 12 can be more effectively reduced.

(Second Embodiment) In a second embodiment, an example of a first signal transmission board of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction, for describing the signal transmission board according to the second embodiment. Note that, in the second embodiment, the same components as those of the signal transmission line substrate 100 of the first embodiment shown in FIG. Is omitted.

The signal transmission board 102 according to the second embodiment
Has a back electrode 16 on the entire surface of the dielectric substrate 10 on the second main surface 10b which is the back surface facing the first main surface 10a. Here, the back surface electrode 16 is formed by gold plating.

In the signal transmission board 102, the electric field generated by the high-frequency signal transmitted through the signal transmission line 12 is divided into the signal transmission line 12 and the ground line
And between the signal transmission line 12 and the back electrode 16. Therefore, the signal transmission board 102
In this case, the distribution of the electric field generated in the substrate 10 between the adjacent signal transmission lines 12 can be further suppressed. As a result, in the second embodiment, the crosstalk between the signal transmission lines 12 can be more effectively suppressed than the crosstalk in the first embodiment.

(Third Embodiment) In a third embodiment, an example of a first signal transmission board and a fourth signal transmission board of the present invention will be described together with reference to FIG.
FIG. 3 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction, for describing a signal transmission board according to the third embodiment. Note that, in the third embodiment, the same components as those of the signal transmission line substrate 100 of the first embodiment shown in FIG. Is omitted.

The signal transmission board 106 of the third embodiment
Has a back surface side groove 18 in a portion corresponding to the back side of the signal transmission line 12 in the second main surface 10b which is the back surface facing the first main surface 10a of the dielectric substrate 10. The back surface side groove 18 is provided with a back surface electrode 16a for grounding. In this embodiment, the back electrode 16a is
Gold plating is provided not only on the back surface side groove 18 but also on the entire surface of the second main surface 10b side.

In this embodiment, the back side groove 18
Is a stripe-shaped groove having a trapezoidal cross section. And this back side groove 18 is used for the signal transmission line 1.
2 in the direction in which the signal transmission lines 12 extend. The side surface of the back side groove 18 is inclined so that the width at the bottom surface of the groove 18 is smaller than the width at the frontage of the groove 18. The width of the frontage of the back side groove 18 is, for example, about 0.4 mm or more. Further, the second main surface 10b of the back side groove 18 is connected to the first main surface 10a.
The depth toward the side is, for example, about 0.2 mm or more.

As described above, the back surface electrode 16 is formed in the back surface side groove 18.
If a is provided, an electric field is also distributed between the signal transmission line 12 and the back surface electrode 16a. For this reason, the generation of the electric field distributed between the adjacent signal transmission lines 12 in the substrate 10 can be further suppressed as compared with the case of the first embodiment. As a result, crosstalk between the signal transmission lines 12 can be more effectively reduced.

In the third embodiment, the second main surface 1
Although the back surface electrode 16a is formed on the entire surface on the 0b side, in the present invention, for example, the back surface electrode 16a is formed only on the surface of the back surface side groove 18.
May be formed. Also, if the back side groove 18 is formed,
The effect of suppressing the warpage of the substrate 10 is expected.

(Fourth Embodiment) In a fourth embodiment, examples of the first signal transmission board and the fifth signal transmission board of the present invention will be described together with reference to FIG.
FIG. 4 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction, for describing a signal transmission board according to a fourth embodiment. Note that, in the fourth embodiment, the same components as those of the signal transmission line substrate 100 of the first embodiment shown in FIG. Is omitted.

The signal transmission board 108 of this embodiment is
A back surface side groove 20 is provided in a portion corresponding to the back side between the signal transmission lines 12 in the second main surface 10b which is the back surface facing the first main surface 10a of the dielectric substrate 10. The back surface side groove 20 is provided with a back surface electrode 16b for grounding. In this embodiment, the back surface electrode 16b is provided by gold plating not only on the back surface side groove 20 but also on the entire surface on the second main surface 10b side.

In this embodiment, the back side groove 20 is formed.
Is a groove in the form of a stripe, and is provided so as to extend in the direction in which the signal transmission line 12 extends in parallel with the signal transmission line 12. In addition, the back surface side groove 20 has a V-shaped cross section. The width of the frontage of the back side groove 20 is, for example, about 0.2 mm or more. Also, the second main surface 10b of the back side groove 20 is formed.
Is from 0.2 to the first main surface 10a side, for example, 0.2
mm or more.

As described above, the back surface electrode 16 is formed in the back surface side groove 20.
If b is provided, an electric field is also distributed between the signal transmission line 12 and the back surface electrode 16b. For this reason, the generation of the electric field distributed between the adjacent signal transmission lines 12 in the substrate 10 can be further suppressed as compared with the case of the first embodiment. As a result, crosstalk between the signal transmission lines 12 can be more effectively reduced.

When the back side groove 20 is formed in a portion corresponding to the back side between the signal transmission lines 12, the distance between the back surface electrode 16b formed in the back side groove 20 and the signal transmission line 12 can be increased. For this reason, the influence of the back surface electrode 16b on the characteristic impedance is small. as a result,
The arrangement condition of the back surface electrode 16b can be relaxed without considering the characteristic impedance.

In the fourth embodiment, the second main surface 1
Although the back electrode 16b is formed on the entire surface on the 0b side, in the present invention, for example, the back electrode 16b is formed only on the surface of the back groove 20.
May be formed. Also, if the back side groove 20 is formed,
The effect of suppressing the warpage of the substrate 10 is expected.

(Fifth Embodiment) In a fifth embodiment, an example of a first signal transmission board of the present invention will be described with reference to FIG. FIG. 5A is a cross-sectional perspective view illustrating a signal transmission board according to a fifth embodiment. FIG. 5B is a cross-sectional view taken along a cross section orthogonal to the signal transmission direction, for describing the signal transmission board and the electric field distribution of the fifth embodiment. Note that, in the fifth embodiment, the same components as those of the signal transmission line substrate 100 of the first embodiment shown in FIG. Is omitted.

As shown in FIG. 5A, in the signal transmission board 110 of this embodiment, the exposed portion of the ground line 14 projects above the first main surface 10a. The height of the protruding portion 14a from the first main surface 10a is preferably, for example, 0.2 mm or more. Further, in the ground line 14 in this embodiment, for example, a groove is formed in a portion between the signal transmission lines 12 on the first main surface 10a of the ceramic substrate 10, and a metal rod is partially inserted into the groove, for example, to have a diameter of It may be formed by filling only half.

Next, FIG. 5B is a sectional view of a signal transmission board 110 according to the fifth embodiment. In FIG. 5B, the signal transmission line 12 provided at the center of the sectional view and the ground lines 14 provided on both sides thereof are shown.
And the distribution of the electric field formed between them is schematically shown by a group of curves having arrows at both ends. As shown by these curves, the electric field generated by the signal transmitted through the signal transmission line 12 is:
It is mainly distributed between the signal transmission line 12 and the nearest ground line 14. As a result, generation of an electric field between adjacent signal transmission lines 12 can be suppressed. Therefore, crosstalk between the signal transmission lines 12 can be reduced.

In particular, the signal transmission board 11 of this embodiment
At 0, since the ground line 14 is projected above the first main surface 10a, the electric field generated above the first main surface 10a causes the electric field between the signal transmission line 12 and the protruding portion 14a of the ground line 14 in the immediate vicinity. Mainly distributed among. For this reason, on the upper side of the first main surface 10a, the generation of the electric field distributed to the adjacent signal transmission lines 12 can be further suppressed. As a result, crosstalk of the signal transmission line 12 can be more effectively reduced.

(Sixth Embodiment) In a sixth embodiment, an example of the first signal transmission board of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view taken along a cut plane orthogonal to a signal transmission direction, for describing a signal transmission board according to a sixth embodiment. Note that, in the sixth embodiment, the same components as those of the signal transmission line substrate 110 of the fifth embodiment shown in FIG. Is omitted.

The signal transmission board 112 according to the sixth embodiment
Has a back electrode 16 on the entire surface of the dielectric substrate 10 on the second main surface 10b which is the back surface facing the first main surface 10a. Here, the back surface electrode 16 is formed by gold plating.

FIG. 6 is a cross-sectional view schematically showing an electric field distribution around the signal transmission line 12 provided at the center of the cross-sectional view by a group of curves having arrows at both ends. As shown by the curve group, in this signal transmission board 112, an electric field generated by an electric signal transmitted through the signal transmission line 12 is generated between the signal transmission line 12 and the immediately adjacent ground line 14, It is also distributed between the signal transmission line 12 and the back electrode 16. For this reason, in the signal transmission board 112, the electric field generated in the board 10 can be further suppressed from being distributed between the adjacent signal transmission lines 12. As a result, in the sixth embodiment,
Crosstalk between the signal transmission lines 12 can be more effectively suppressed than the crosstalk in the fifth embodiment.

(Seventh Embodiment) In a seventh embodiment, an example of a first signal transmission board and a fourth signal transmission board of the present invention will be described together with reference to FIG.
FIG. 7 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction, for describing a signal transmission board according to a seventh embodiment. In the seventh embodiment, the same components as those of the signal transmission line substrate 110 of the fifth embodiment shown in FIG. Is omitted.

The signal transmission board 114 according to the seventh embodiment
Has a back surface side groove 18 in a portion corresponding to the back side of the signal transmission line in the second main surface 10b which is the back surface facing the first main surface 10a of the dielectric substrate 10. The back surface side groove 18 is provided with a back surface electrode 16a for grounding. In this embodiment, the back surface electrode 16a is provided by gold plating not only on the back surface side groove 18 but also on the entire surface on the second main surface 10b side.

In this embodiment, the back side groove 18
Has a stripe shape extending in the direction in which the signal transmission line 12 extends, and has a trapezoidal cross-sectional shape. That is,
The side surface of the back-side groove 18 is inclined such that the width of the groove 18 at the bottom surface is smaller than the width of the groove 18 at the frontage. The width of the frontage of the back side groove 18 is, for example, 0.1 mm.
It is about 4 mm or more. In addition, the second groove 18
The depth from the main surface 10b toward the first main surface 10a is
For example, it is about 0.2 mm or more.

As described above, the back surface electrode 16 is formed in the back surface side groove 18.
If a is provided, an electric field is also distributed between the signal transmission line 12 and the back surface electrode 16a. For this reason, the generation of the electric field distributed between the adjacent signal transmission lines 12 in the substrate 10 can be further suppressed as compared with the case of the first embodiment. As a result, crosstalk between the signal transmission lines 12 can be more effectively reduced.

In the seventh embodiment, the second main surface 1
Although the back surface electrode 16a is formed on the entire surface on the 0b side, in the present invention, for example, the back surface electrode 16a is formed only on the surface of the back surface side groove 18.
May be formed.

(Eighth Embodiment) In an eighth embodiment, an example of the first signal transmission board and the fifth signal transmission board of the present invention will be described together with reference to FIG.
FIG. 8 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction, for explaining the signal transmission board according to the eighth embodiment. Note that, in the eighth embodiment, the same components as those of the signal transmission line substrate 110 of the fifth embodiment shown in FIG. Is omitted.

The signal transmission board 116 of this embodiment is
A back surface side groove 20 is provided in a portion corresponding to the back side between the signal transmission lines 12 in the second main surface 10b which is the back surface facing the first main surface 10a of the dielectric substrate 10. The back surface side groove 20 is provided with a back surface electrode 16b for grounding. In this embodiment, the back surface electrode 16 is provided by gold plating not only on the back surface side groove 20 but also on the entire surface on the second main surface 10b side.

In this embodiment, the back side groove 18
Is V-shaped. The width of the frontage of the back side groove 20 is, for example, about 0.2 mm or more. Further, the second main surface 10b of the back side groove 20 is connected to the first main surface 10a.
The depth toward the side is, for example, about 0.2 mm or more.

As described above, the back surface electrode 16 is formed in the back surface side groove 20.
If b is provided, an electric field is also distributed between the signal transmission line 12 and the back surface electrode 16b. For this reason, the generation of the electric field distributed between the adjacent signal transmission lines 12 in the substrate 10 can be further suppressed as compared with the case of the fifth embodiment. As a result, crosstalk between the signal transmission lines 12 can be more effectively reduced.

When the back surface side groove 20 is formed in a portion corresponding to the back side between the signal transmission lines 12, the distance between the back surface electrode 16b formed in the back surface side groove 20 and the signal transmission line 12 can be increased. For this reason, the influence of the back surface electrode 16b on the characteristic impedance is small. as a result,
The arrangement condition of the back surface electrode 16b can be relaxed without considering the characteristic impedance.

In the eighth embodiment, the second main surface 1
Although the back electrode 16b is formed on the entire surface on the 0b side, in the present invention, for example, the back electrode 16b is formed only on the surface of the back groove 20.
May be formed.

(Ninth Embodiment) In a ninth embodiment, an example of the second signal transmission board of the present invention will be described with reference to FIG. FIG. 9A is a cross-sectional perspective view illustrating a signal transmission board according to a ninth embodiment. FIG. 9B is a cross-sectional view taken along a cross-section orthogonal to the signal transmission direction for explaining the signal transmission board and the electric field distribution of the ninth embodiment. In the ninth embodiment, the same components as those of the signal transmission line substrate 100 of the first embodiment shown in FIG. Is omitted.

The signal transmission board 118 of the ninth embodiment
Has a plurality of signal transmission lines 12 on the first main surface 30a of the dielectric substrate 30. Here, the dielectric substrate 30
The resin substrate 30 is used. The thickness of the resin substrate 30 is about 1 mm. The resin substrate has a dielectric constant of about 3. Further, as the dielectric substrate 30, for example, a ceramic substrate may be used. The signal transmission line 12 is formed by applying gold plating on a nickel base (not shown) formed on the resin substrate 30.

The signal transmission board 118 has a V-shaped groove 22 having a V-shaped cross section at the first main surface 30a between the signal transmission lines 12. A ground line 34 is provided on the slope 22a of the V-shaped groove 22 so as to extend in parallel with the extending direction of the signal transmission line. The width of the frontage of the V-shaped groove 22 is about 0.2 mm or more. Also,
The depth of the V-shaped groove 22 is about 0.2 mm or more.
The ground line 34 is also electrically grounded (GND) as in the other embodiments.

In designing the specific dimensions of the ground line 34 and the specific distance between the ground line 34 and the signal transmission line 12, the signal transmission line 12 and the ground line
4, the characteristic impedance of the signal transmission board 1
The system is designed so as to match the characteristic impedance (for example, 50Ω) of the system including the optical transmission module, for example, which is constituted by the device 18. When designing the characteristic impedance,
It is preferable to use a conventionally known computer simulation technique.

In forming the ground line 34, for example, first, a photoresist mask pattern (not shown) having an opening in the V-shaped groove 22 is formed.
Next, the V-shaped groove 22 exposed at the opening of the mask pattern is formed.
Is plated with copper by electroless plating.
Next, electrolytic plating is performed in the order of nickel plating and gold plating using the copper plating as a base. Next, the ground pattern 34 is obtained by removing the mask pattern. When the ground line 34 is formed, the signal transmission line 12 may be formed by sharing the mask pattern and the plating process.

The shape of the V-shaped groove 22 is
Can be easily formed by providing a projection for forming a V-shaped groove in the forming mold when the injection is formed.

In forming a V-shaped groove by injection, the cross-sectional shape of the groove is V-shaped, so that the forming die can be more easily removed than in the case of forming a groove having a rectangular cross-sectional shape. . For this reason, when forming a V-shaped groove, it is possible to form the injection by narrowing the width of the groove as compared with the case of forming a rectangular groove. For example, when forming a rectangular groove, the width of the groove needs to be about 0.4 mm or more in order to maintain the strength of the forming die. On the other hand, when forming the V-shaped groove, the width of the groove can be reduced to about 0.2 mm.

As described above, when the ground line 34 is provided in the V-shaped groove 22 in the first main surface 30a between the signal transmission lines 12, the electric field generated by the high-frequency signal transmitted through the signal transmission line 12 is reduced. Ground line 34 closest to 12
Mainly distributed between As a result, generation of an electric field between adjacent signal transmission lines 12 can be suppressed. Therefore, crosstalk between the signal transmission lines 12 can be reduced.

In particular, the signal transmission board 1 of the ninth embodiment
In 18, the ground line 34 is provided in the V-shaped groove 22, so that the electric field generated in the substrate 30 is effectively distributed between the ground line 34 and the signal transmission line 12. As a result, generation of an electric field between adjacent signal transmission lines 12 can be effectively suppressed. Therefore, crosstalk between the signal transmission lines 12 can be more effectively reduced.

In addition, in the signal transmission line board 118, since the ground line 34 is provided on the slope 22a of the V-shaped groove 22, an electric field generated above the first main surface 30a of the board 30 is generated by the slope 22a. Ground line 34 and signal transmission line 1
The effect of facilitating distribution between the two is expected.

(Tenth Embodiment) In a tenth embodiment, examples of the second signal transmission board and the fourth signal transmission board of the present invention will be described together. FIG. 10 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction for explaining the signal transmission board according to the tenth embodiment. In the tenth embodiment, the same components as those of the signal transmission line board 118 of the ninth embodiment shown in FIG. Is omitted.

The signal transmission board 120 according to the tenth embodiment
Has a back surface side groove 18 in a portion corresponding to the back side of the signal transmission line 12 in the second main surface 30b which is the back surface facing the first main surface 30a of the resin substrate 30. The back surface side groove 18 is provided with a back surface electrode 16a for grounding. In this embodiment, the back surface electrode 16a is provided by gold plating not only on the back surface side groove 18 but also on the entire surface on the second main surface 30b side.

In this embodiment, the back side groove 18
Has a trapezoidal cross section. That is, the side surface of the back side groove 18 is inclined such that the width of the bottom surface of the groove 18 is smaller than the width of the frontage of the groove 18. Also, this back side groove 1
The width of the frontage 8 is, for example, about 0.4 mm or more. The depth of the back side groove 18 from the second main surface 30b toward the first main surface 30a is, for example, about 0.2 mm or more.

As described above, the back surface electrode 16 is formed in the back surface side groove 18.
If a is provided, an electric field is also distributed between the signal transmission line 12 and the back surface electrode 16a. Therefore, the generation of an electric field distributed between adjacent signal transmission lines 12 in the substrate 30 can be further suppressed as compared with the case of the ninth embodiment. As a result, crosstalk between the signal transmission lines 12 can be more effectively reduced.

In the tenth embodiment, the back electrode 16a is formed on the entire surface of the second main surface 30b, but in the present invention, for example, the back electrode 16a is formed only on the surface of the back groove 18.
a may be formed.

(Eleventh Embodiment) In the eleventh embodiment, examples of the second signal transmission board and the fifth signal transmission board of the present invention will be described together. FIG.
FIG. 32 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction, used for describing a signal transmission board according to an eleventh embodiment. In the eleventh embodiment, the same components as those of the signal transmission line board 118 of the ninth embodiment shown in FIG. Is omitted.

The signal transmission board 122 of this embodiment is
The resin substrate 30 has a back surface side groove 20 in a portion corresponding to the back surface between the signal transmission lines 12 in the second main surface 30b which is the back surface facing the first main surface 30a. The back surface side groove 20 is provided with a back surface electrode 16b for grounding. In this embodiment, the back surface electrode 16b is provided by gold plating not only on the back surface side groove 20 but also on the entire surface on the second main surface 30b side.

In this embodiment, the back side groove 18
Is V-shaped. The width of the frontage of the back side groove 20 is, for example, about 0.2 mm or more. Further, the second main surface 30b of the back side groove 20 is connected to the first main surface 30a.
The depth toward the side is, for example, about 0.2 mm or more.

Thus, the back surface electrode 16 is formed in the back surface side groove 20.
If b is provided, an electric field is also distributed between the signal transmission line 12 and the back surface electrode 16b. Therefore, the generation of an electric field distributed between adjacent signal transmission lines 12 in the substrate 30 can be further suppressed as compared with the case of the ninth embodiment. As a result, crosstalk between the signal transmission lines 12 can be more effectively reduced.

When the back surface side groove 20 is formed in a portion corresponding to the back side between the signal transmission lines 12, the distance between the back surface electrode 16b formed in the back surface side groove 20 and the signal transmission line 12 can be increased. For this reason, the influence of the back surface electrode 16b on the characteristic impedance is small. as a result,
The arrangement condition of the back surface electrode 16b can be relaxed without considering the characteristic impedance.

In the eleventh embodiment, the back electrode 16b is formed on the entire surface of the second main surface 30b, but in the present invention, for example, the back electrode 16b is formed only on the surface of the back groove 20.
b may be formed.

(Twelfth Embodiment) In the twelfth embodiment, an example of the third signal transmission board of the present invention will be described. FIG. 12 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction, for describing a signal transmission board according to a twelfth embodiment. In the twelfth embodiment, the same components as those of the signal transmission line substrate 100 of the first embodiment shown in FIG. Is omitted.

The signal transmission board 124 of the twelfth embodiment
Has a plurality of signal transmission lines 12 on a first main surface 30 a of a dielectric substrate 30. Here, the dielectric substrate 3
As 0, the resin substrate 30 is used as in the ninth embodiment.

The signal transmission board 124 has, on the first main surface 30 a between the signal transmission lines 12, a protruding portion 24 extending in parallel with the direction in which the signal transmission line 12 extends. I have. Then, the signal transmission board 124
The ground line 36 is provided on the slope 26 of the projecting portion 24. The cross-sectional shape of the protruding portion 24 at the cut crossing the ridge is trapezoidal. The width of the bottom surface of the protruding portion 24 is about 0.4 mm or more. The width of the upper surface of the protruding portion 24 is about 0.2 mm or more.

In designing the specific dimensions of the ground line 36 and the specific distance between the ground line 34 and the signal transmission line 12, the signal transmission line 12 and the ground line
6 is designed to match the characteristic impedance (for example, 50Ω) of the system including the optical transmission module. In designing the characteristic impedance, a conventionally well-known computer simulation technique may be used.

In forming the ground line 36, for example, first, a photoresist mask pattern (not shown) having an opening in the protruding portion 24 is formed.
Next, the protruding portion 24 exposed at the opening of the mask pattern
The surface including the slope 26 is plated with copper by electroless plating. Next, electrolytic plating is performed in the order of nickel plating and gold plating using the copper plating as a base. Next, the ground pattern 36 is obtained by removing the mask pattern. When forming the ground line 36, the signal transmission line 12 may be formed by sharing the mask pattern and the plating process. The ground line 36 is also electrically grounded (GND) as in the other embodiments.

The shape of the protruding portion 24 is
Can be easily formed by providing a concave portion for forming a protruding portion in the forming die when forming by injection.

As described above, when the ground line 36 is provided on the slope 26 of the protruding portion 24 of the first main surface 30a between the signal transmission lines 12, the electric field generated by the high-frequency signal transmitted through the signal transmission line 12 is reduced. It is mainly distributed between the line 12 and the nearest ground line 36. As a result, generation of an electric field between adjacent signal transmission lines 12 can be suppressed. Therefore, crosstalk between the signal transmission lines 12 can be reduced.

In particular, the signal transmission board 12 of this embodiment
In FIG. 4, since the ground line 36 is provided on the slope 26 of the protruding portion 24, of the electric field generated in the substrate 30 and the first main surface 30 a of the substrate 30, respectively, The generated electric field is more effectively distributed between the signal transmission line 12 and the ground line 36. As a result, generation of an electric field between adjacent signal transmission lines 12 can be more effectively suppressed. Therefore, it is possible to more effectively reduce the crosstalk of the electric field generated above the first main surface 30 between the signal transmission lines 12.

In this embodiment, the ground line 36 is provided on the slope 26 of the protrusion having a trapezoidal cross section and on the upper surface of the protrusion. However, the ground line 36 may be provided only on the slope 26.

In this embodiment, the cross-sectional shape of the protruding portion is trapezoidal. However, the cross-sectional shape of the protruding portion may be any suitable shape including the shapes shown in the following modifications. it can.

(Modification) A modification of the twelfth embodiment will be described with reference to FIG. FIGS. 13A and 13B are cross-sectional views taken along a cut plane orthogonal to the signal transmission direction, for describing a signal transmission board according to a modification of the twelfth embodiment.

In this modification, the same components as those of the signal transmission line substrate 124 of the twelfth embodiment shown in FIG. 12 are denoted by the same reference numerals, and will be described in detail. Is omitted.

In the signal transmission board 126 of the modified example shown in FIG. 13A, the cross-sectional shape of the projection 24a is triangular. The ground line 36 is provided on the triangular slope 26a.

In the signal transmission board 128 of the modified example shown in FIG. 13B, the cross-sectional shape of the protruding portion 24b is semicircular. The ground line 36 is provided on the curved slope 26b on the outer periphery of the semicircle.

(Thirteenth Embodiment) In a thirteenth embodiment, an example of a third signal transmission board and a fourth signal transmission board of the present invention will be described together with reference to FIG. FIG. 14 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction for explaining the signal transmission board according to the thirteenth embodiment. In the thirteenth embodiment, FIG.
2, the same components as those of the signal transmission line board 124 according to the twelfth embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The signal transmission board 130 of the thirteenth embodiment
Has a back surface side groove 18 in a portion corresponding to the back side of the signal transmission line 12 in the second main surface 30b which is the back surface facing the first main surface 30a of the resin substrate 30. The back surface side groove 18 is provided with a back surface electrode 16a for grounding. In this embodiment, the back surface electrode 16a is provided by gold plating not only on the back surface side groove 18 but also on the entire surface on the second main surface 30b side.

In this embodiment, the back side groove 18
Has a trapezoidal cross section. That is, the side surface of the back side groove 18 is inclined such that the width of the bottom surface of the groove 18 is smaller than the width of the frontage of the groove 18. Also, this back side groove 1
The width of the frontage 8 is, for example, about 0.4 mm or more. The depth of the back side groove 18 from the second main surface 30b toward the first main surface 30a is, for example, about 0.2 mm or more.

As described above, the back surface electrode 16 is formed in the back surface side groove 18.
If a is provided, an electric field is also distributed between the signal transmission line 12 and the back surface electrode 16a. Therefore, the generation of an electric field distributed between adjacent signal transmission lines 12 in the substrate 30 can be further suppressed as compared with the twelfth embodiment. As a result, crosstalk between the signal transmission lines 12 can be more effectively reduced.

In the thirteenth embodiment, the back electrode 16a is formed on the entire surface of the second main surface 30b, but in the present invention, for example, the back electrode 16a is formed only on the surface of the back groove 18.
a may be formed.

(Fourteenth Embodiment) In a fourteenth embodiment, an example of a third signal transmission board and a fifth signal transmission board of the present invention will be described together with reference to FIG. FIG. 15 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction, for describing the signal transmission board according to the fourteenth embodiment. Incidentally, in the fourteenth embodiment, FIG.
Signal transmission line board 124 of the twelfth embodiment shown in FIG.
The same components as those of are denoted by the same reference numerals,
A detailed description thereof will be omitted.

The signal transmission board 132 of this embodiment is
The resin substrate 30 has a back surface side groove 20 in a portion corresponding to the back surface between the signal transmission lines 12 in the second main surface 30b which is the back surface facing the first main surface 30a. The back surface side groove 20 is provided with a back surface electrode 16b for grounding. In this embodiment, the back surface electrode 16b is provided by gold plating not only on the back surface side groove 20 but also on the entire surface on the second main surface 30b side.

In this embodiment, the back side groove 18
Is V-shaped. The width of the frontage of the back side groove 20 is, for example, about 0.2 mm or more. Further, the second main surface 30b of the back side groove 20 is connected to the first main surface 30a.
The depth toward the side is, for example, about 0.2 mm or more.

As described above, the back surface electrode 16 is formed in the back surface side groove 20.
If b is provided, an electric field is also distributed between the signal transmission line 12 and the back surface electrode 16b. Therefore, the generation of an electric field distributed between adjacent signal transmission lines 12 in the substrate 30 can be further suppressed as compared with the twelfth embodiment. As a result, crosstalk between the signal transmission lines 12 can be more effectively reduced.

When the back surface side groove 20 is formed in a portion corresponding to the back side between the signal transmission lines 12, the distance between the back surface electrode 16b formed in the back surface side groove 20 and the signal transmission line 12 can be increased. For this reason, the influence of the back surface electrode 16b on the characteristic impedance is small. as a result,
The arrangement condition of the back surface electrode 16b can be relaxed without considering the characteristic impedance.

In the fourteenth embodiment, the back electrode 16b is formed on the entire surface of the second main surface 30b, but in the present invention, for example, the back electrode 16b is formed only on the surface of the back groove 20.
b may be formed.

(Fifteenth Embodiment) In a fifteenth embodiment, an example of a second signal transmission board and a third signal transmission board of the present invention will be described together with reference to FIG. FIG. 16 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction for explaining the signal transmission board according to the fifteenth embodiment. Note that, in the fifteenth embodiment, FIG.
The same reference numerals are given to the same components as those of the signal transmission line substrate 100 of the first embodiment shown in FIG. 1, and the detailed description is omitted.

[0127] The signal transmission board 134 of the fifteenth embodiment.
Has a plurality of signal transmission lines 12 on a first main surface 30 a of a resin substrate 30. The thickness of the resin substrate 30 is
It is about 1 mm. The resin substrate has a dielectric constant of 3
It is about. In addition, the signal transmission line 12 is
It is formed by applying gold plating on a nickel base (not shown) formed thereon.

The signal transmission board 134 has two V-shaped grooves 22 having a V-shaped cross section in the first main surface 30a between the signal transmission lines 12 in parallel with each other.
The signal transmission board 134 has, on the first main surface 30 a between the two V-shaped grooves 22, a protruding portion 24 that extends parallel to the extending direction of the V-shaped groove 22 and protrudes. I have.

In other words, the signal transmission board 134 is provided on the first main surface 30a between the signal transmission lines 12 so as to extend in the direction parallel to the direction in which the signal transmission lines 12 extend.
And a V-shaped groove 22 extending in the first main surface 30a between the projecting portion 24 and the signal transmission line 12 in a direction parallel to the extending direction of the projecting portion 24. 22 has a ground line 38 on the slope 26.

[0130] In this embodiment, the cross-sectional shape at the cross section that crosses the ridge of the protruding portion is trapezoidal. Also, here, one side of the slope 26 of the V-shaped groove 22 and the slope 2 of the projecting portion
6 are continuous. A ground line 38 is provided on the slope 26 of the V-shaped groove and the slope 26 of the protruding portion 24. In this embodiment, a ground line 38 is also provided on the upper surface of the protrusion 24. Also, this ground line 38
Is electrically grounded (G) as in the other embodiments.
ND).

The width of the front of the V-shaped groove 22 is about 0.2 m.
m. The V-shaped groove 22 has a depth of about 0.2 mm with reference to the surface on which the signal transmission line 12 is formed. The height of the protruding portion 24 with respect to the surface on which the signal transmission line 12 is formed is about 0.2 mm. In addition, two V-shaped grooves 22 between adjacent signal transmission lines 12
The distance between the distant edges of the
It is. The distance between the V-shaped groove 22 and the signal transmission line 12 is about 0.2 mm.

In designing the specific dimensions of the ground line 38 and the specific distance between the ground line 38 and the signal transmission line 12, the signal transmission line 12 and the ground line
8 is designed to match the characteristic impedance (for example, 50Ω) of the system including the optical transmission module. In designing the characteristic impedance, a conventionally well-known computer simulation technique may be used.

In forming the ground line 38, for example, first, a mask pattern (not shown) of a photoresist having an opening on the V-shaped groove 22 and the projecting portion 24 is formed. Next, copper plating is applied to the slope 26 and the upper surface of the V-shaped groove 22 and the protruding portion 24 exposed at the opening of the mask pattern by electroless plating. Next, electrolytic plating is performed in the order of nickel plating and gold plating using the copper plating as a base. Next, the ground pattern 38 is obtained by removing the mask pattern. When forming the ground line 38, the signal transmission line 12 may be formed by sharing the mask pattern and the plating process.

Further, the shape of the V-shaped groove 22 is
Can be easily formed by providing the forming die with a convex portion for forming a V-shaped groove and a concave portion for forming a protruding portion.

As described above, the two V-shaped grooves 22 and the protruding portions 24 interposed between the V-shaped grooves 22 are provided in the first main surface 30a between the signal transmission lines 12, and the V-shaped grooves 22 are formed. If the ground line 38 is provided on the slope 26 of the projection 24,
An electric field generated by a high-frequency signal transmitted through the signal transmission line 12 is mainly distributed between the signal transmission line 12 and the ground line 38. As a result, the generation of an electric field between adjacent signal transmission lines can be suppressed. Therefore, crosstalk between signal transmission lines can be reduced.

In particular, in this embodiment, the electric field generated above the first main surface is mainly distributed between signal transmission line 12 and ground line 38 formed on slope 26 of projection 24. I do. The electric field generated in the substrate 30 is
It is mainly distributed between the signal transmission line 12 and the ground line 38 formed on the slope 26 of the V-shaped groove 22. Therefore, according to the signal transmission board 134 of this embodiment, the distribution of the electric field between the adjacent signal transmission lines is reduced by the signal transmission boards 118 and 12 of the ninth and twelfth embodiments.
4 can be more effectively suppressed. Therefore, in the signal transmission board 134, the signal transmission line 12
The crosstalk between them can be further reduced.

(Sixteenth Embodiment) In a sixteenth embodiment, examples of the second, third, and fourth signal transmission boards of the present invention will be described together with reference to FIG. FIG. 17 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction for describing the signal transmission board according to the sixteenth embodiment. In the sixteenth embodiment, the same components as those of the signal transmission line board 134 of the fifteenth embodiment shown in FIG. Is omitted.

The signal transmission board 136 according to the sixteenth embodiment
Has a back surface side groove 18 in a portion corresponding to the back side of the signal transmission line 12 in the second main surface 30b which is the back surface facing the first main surface 30a of the resin substrate 30. The back surface side groove 18 is provided with a back surface electrode 16a for grounding. In this embodiment, the back surface electrode 16a is provided by gold plating not only on the back surface side groove 18 but also on the entire surface on the second main surface 30b side.

In this embodiment, the back side groove 18
Has a trapezoidal cross section. That is, the side surface of the back side groove 18 is inclined such that the width of the bottom surface of the groove 18 is smaller than the width of the frontage of the groove 18. Also, this back side groove 1
The width of the frontage 8 is, for example, about 0.4 mm or more. The depth of the back side groove 18 from the second main surface 30b toward the first main surface 30a is, for example, about 0.2 mm or more.

As described above, the back surface electrode 16 is formed in the back surface side groove 18.
If a is provided, an electric field is also distributed between the signal transmission line 12 and the back surface electrode 16a. Therefore, the generation of an electric field distributed between adjacent signal transmission lines 12 in the substrate 30 can be further suppressed as compared with the case of the fifteenth embodiment. As a result, crosstalk between the signal transmission lines 12 can be more effectively reduced.

In the sixteenth embodiment, the back electrode 16a is formed on the entire surface of the second main surface 30b, but in the present invention, for example, the back electrode 16a is formed only on the surface of the back groove 18.
a may be formed.

(Seventeenth Embodiment) In the seventeenth embodiment, examples of the second, third, and fifth signal transmission boards of the present invention will be described together with reference to FIG. FIG. 18 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction for explaining the signal transmission board according to the seventeenth embodiment. Note that, in the seventeenth embodiment, the same components as those of the signal transmission line board 134 of the fifteenth embodiment shown in FIG. Is omitted.

The signal transmission board 138 of the seventeenth embodiment
Has a back surface side groove 20 in a portion corresponding to the back side between the signal transmission lines 12 in the second main surface 30b which is the back surface facing the first main surface 30a of the resin substrate 30. The back surface side groove 20 is provided with a back surface electrode 16b for grounding. In this embodiment, the back electrode 16b is
Gold plating is provided not only on the back surface side groove 20 but also on the entire surface on the second main surface 30b side.

In this embodiment, the back side groove 18 is formed.
Is V-shaped. The width of the frontage of the back side groove 20 is, for example, about 0.2 mm or more. Further, the second main surface 30b of the back side groove 20 is connected to the first main surface 30a.
The depth toward the side is, for example, about 0.2 mm or more.

As described above, the back surface electrode 16 is formed in the back surface side groove 20.
If b is provided, an electric field is also distributed between the signal transmission line 12 and the back surface electrode 16b. Therefore, the generation of an electric field distributed between adjacent signal transmission lines 12 in the substrate 30 can be further suppressed as compared with the case of the fifteenth embodiment. As a result, crosstalk between the signal transmission lines 12 can be more effectively reduced.

When the back surface side groove 20 is formed in a portion corresponding to the back side between the signal transmission lines 12, the distance between the back surface electrode 16b formed in the back surface side groove 20 and the signal transmission line 12 can be increased. For this reason, the influence of the back surface electrode 16b on the characteristic impedance is small. as a result,
The arrangement condition of the back surface electrode 16b can be relaxed without considering the characteristic impedance.

In the seventeenth embodiment, the back electrode 16b is formed on the entire surface of the second main surface 30b, but in the present invention, for example, the back electrode 16b is formed only on the surface of the back groove 20.
b may be formed.

(Eighteenth Embodiment) In an eighteenth embodiment, an example of a fourth signal transmission board of the present invention will be described with reference to FIG. FIG. 19 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction for describing the signal transmission board of the eighteenth embodiment. In the eighteenth embodiment, the same components as those of the signal transmission line substrate 100 of the first embodiment shown in FIG. Is omitted.

Signal transmission board 140 of the eighteenth embodiment
Has a back surface side groove 18 in a portion corresponding to the back side of the signal transmission line 12 in the second main surface 30b which is the back surface facing the first main surface 30a of the resin substrate 30. The back surface side groove 18 is provided with a back surface electrode 16a for grounding. In this embodiment, the back surface electrode 16a is provided by gold plating not only on the back surface side groove 18 but also on the entire surface on the second main surface 30b side.

In this embodiment, the back side groove 18 is used.
Has a trapezoidal cross section. That is, the side surface of the back side groove 18 is inclined such that the width of the bottom surface of the groove 18 is smaller than the width of the frontage of the groove 18. Also, this back side groove 1
The width of the frontage 8 is, for example, about 0.4 mm or more. The depth of the back side groove 18 from the second main surface 30b toward the first main surface 30a is, for example, about 0.2 mm or more.

As described above, the back surface electrode 16 is formed in the back surface side groove 18.
If a is provided, an electric field is also distributed between the signal transmission line 12 and the back surface electrode 16a. For this reason, the generation of the electric field distributed between the adjacent signal transmission lines 12 in the substrate 30 can be further suppressed as compared with the case of the first embodiment. As a result, crosstalk between the signal transmission lines 12 can be more effectively reduced.

In the eighteenth embodiment, the back electrode 16a is formed on the entire surface of the second main surface 30b, but in the present invention, for example, the back electrode 16a is formed only on the surface of the back groove 18.
a may be formed.

(Nineteenth Embodiment) In the nineteenth embodiment, an example of the fifth signal transmission board of the present invention will be described with reference to FIG. FIG. 20 is a cross-sectional view taken along a cut plane orthogonal to the signal transmission direction for explaining the signal transmission board according to the nineteenth embodiment. Note that, in the nineteenth embodiment, the same components as those of the signal transmission line substrate 100 of the first embodiment shown in FIG. Is omitted.

Signal transmission board 142 of the nineteenth embodiment
Has a back surface side groove 20 in a portion corresponding to the back side between the signal transmission lines 12 in the second main surface 30b which is the back surface facing the first main surface 30a of the resin substrate 30. The back surface side groove 20 is provided with a back surface electrode 16b for grounding. In this embodiment, the back electrode 16b is
Gold plating is provided not only on the back surface side groove 20 but also on the entire surface on the second main surface 30b side.

In this embodiment, the back side groove 18 is formed.
Is V-shaped. The width of the frontage of the back side groove 20 is, for example, about 0.2 mm or more. Further, the second main surface 30b of the back side groove 20 is connected to the first main surface 30a.
The depth toward the side is, for example, about 0.2 mm or more.

As described above, the back surface electrode 16 is formed in the back surface side groove 20.
If b is provided, an electric field is also distributed between the signal transmission line 12 and the back surface electrode 16b. For this reason, the generation of the electric field distributed between the adjacent signal transmission lines 12 in the substrate 30 can be further suppressed as compared with the case of the first embodiment. As a result, crosstalk between the signal transmission lines 12 can be more effectively reduced.

When the back surface side groove 20 is formed in a portion corresponding to the back side between the signal transmission lines 12, the distance between the back surface electrode 16b formed in the back surface side groove 20 and the signal transmission line 12 can be increased. For this reason, the influence of the back surface electrode 16b on the characteristic impedance is small. as a result,
The arrangement condition of the back surface electrode 16b can be relaxed without considering the characteristic impedance.

In the nineteenth embodiment, the back electrode 16b is formed on the entire surface of the second main surface 30b, but in the present invention, for example, the back electrode 16b is formed only on the surface of the back groove 20.
b may be formed.

In the above-described embodiment, only examples in which these inventions are formed using specific materials and under specific conditions have been described. However, these inventions can be subjected to many changes and modifications. For example, in the above-described embodiment,
Although the case where a plurality of linear signal transmission lines are arranged in parallel has been described, in the present invention, the shape of the signal transmission line is not limited to this. For example, the intervals between the signal transmission lines may be non-uniform. Further, the signal transmission line need not be a straight line.

Further, in the above-described embodiment, the ground line, the V-shaped groove, and the projecting portion are respectively extended in parallel with the extending direction of the signal transmission line. It is sufficient if they are along the extending direction, and they need not necessarily be parallel.

In the above-described embodiment, the ground line is formed on the entire slope of the V-shaped groove. However, in the present invention, for example, signal transmission is performed only on one side of the V-shaped groove or only on a part of the slope. A ground line extending along the extending direction of the line may be provided.

[0162]

According to the first signal transmission board of the present invention, since the ground line embedded in the dielectric substrate between the signal transmission lines is provided, the electric field generated by the signal transmitted through the signal transmission line is reduced. , Mainly distributed between the signal transmission line and the nearest ground line. As a result, the generation of an electric field between adjacent signal transmission lines can be suppressed. Therefore, crosstalk between signal transmission lines can be reduced.

In particular, in the first signal transmission board of the present invention, since the ground line is embedded in the board, of the electric fields generated above the first main surface of the board and in the board, respectively, The generated electric field is more effectively distributed between the signal transmission line and the ground line. As a result, it is possible to more effectively suppress the generation of an electric field between adjacent signal transmission lines. Therefore, crosstalk between signal transmission lines can be more effectively reduced.

Further, in the first signal transmission board of the present invention, if the ground line is also projected on the first main surface, the first
The electric field generated above the main surface is mainly distributed between the signal transmission line and the ground line formed at the protruding portion immediately near the signal transmission line. For this reason, the generation of an electric field distributed between adjacent signal transmission lines can be further suppressed above the first main surface. As a result, crosstalk between signal transmission lines can be more effectively reduced.

According to the second signal transmission board of the present invention, since the ground line is provided in the V-shaped groove in the dielectric substrate between the signal transmission lines, the electric field generated by the signal transmitted through the signal transmission line is provided. Are mainly distributed between the signal transmission line and the nearest ground line. As a result, the generation of an electric field between adjacent signal transmission lines can be suppressed. For this reason,
Crosstalk between signal transmission lines can be reduced.

In particular, in the second signal transmission board of the present invention, since the ground line is provided in the V-shaped groove, the electric field generated in the board is effectively generated between the ground line and the signal transmission line. Distribute. As a result, generation of an electric field between adjacent signal transmission lines can be effectively suppressed. Therefore, crosstalk between signal transmission lines can be more effectively reduced.

In addition, in the second signal transmission line board of the present invention, since the ground line is provided on the slope of the V-shaped groove, the electric field generated above the first main surface of the board is applied to the ground on the slope. The effect of facilitating distribution between the line and the signal transmission line is expected.

Further, in the second signal transmission board of the present invention, two V-shaped grooves are provided between the signal transmission lines, and a ground line is provided on the slope of the projection between the two V-shaped grooves. For example, the electric field generated above the first main surface is mainly distributed between the signal transmission line and the ground line formed in the protruding portion immediately near the signal transmission line. As a result, the generation of an electric field between adjacent signal transmission lines can be more effectively suppressed above the first main surface. For this reason, crosstalk between signal transmission lines can be more effectively reduced.

According to the third signal transmission board of the present invention, since the ground line is provided on the slope of the projecting portion of the dielectric substrate between the signal transmission lines, it is generated by a signal transmitted through the signal transmission line. The electric field is mainly distributed between the signal transmission line and the nearest ground line. As a result, the generation of an electric field between adjacent signal transmission lines can be suppressed. Therefore, crosstalk between signal transmission lines can be reduced.

Particularly, in the third signal transmission board of the present invention, since the ground line is provided on the slope of the protruding portion, of the electric field generated above the first main surface of the board and in the board, respectively. The electric field generated above one main surface is more effectively distributed between the signal transmission line and the ground line. As a result, it is possible to more effectively suppress the generation of an electric field between adjacent signal transmission lines. Therefore, it is possible to more effectively reduce the crosstalk of the electric field generated above the first main surface between the signal transmission lines.

In the third signal transmission board of the present invention, if a ground line is provided on the slope of the V-shaped groove in the dielectric substrate portion between the signal transmission line and the projection, the electric field in the board becomes
The distribution is more efficient between the signal transmission line and the ground line formed in the V-groove in the immediate vicinity. For this reason, crosstalk caused by an electric field generated in the substrate can be more effectively reduced.

According to the fourth signal transmission board of the present invention, since the back surface electrode is provided in the back surface side groove on the back side of the signal transmission line, an electric field is distributed between the signal transmission line and the back surface electrode. . As a result, it is possible to suppress the generation of an electric field between adjacent signal transmission lines in the substrate. For this reason, crosstalk between signal transmission lines can be more effectively reduced.

According to the fifth signal transmission board of the present invention, since the back surface electrode is provided in the back surface side groove between the signal transmission lines, an electric field is distributed between the signal transmission line and the back surface electrode. I do. As a result, it is possible to suppress the generation of an electric field between adjacent signal transmission lines in the substrate.
For this reason, crosstalk between signal transmission lines can be more effectively reduced.

[Brief description of the drawings]

FIG. 1A is a sectional perspective view illustrating a signal transmission board according to a first embodiment, and FIG. 1B is a cross-sectional perspective view illustrating an electric field distribution of the signal transmission board according to the first embodiment. FIG.

FIG. 2 is a cross-sectional view for explaining a signal transmission board according to a second embodiment;

FIG. 3 is a cross-sectional view for explaining a signal transmission board according to a third embodiment;

FIG. 4 is a cross-sectional view for describing a signal transmission board according to a fourth embodiment;

FIG. 5A is a cross-sectional perspective view for explaining a signal transmission board according to a fifth embodiment, and FIG. 5B is a diagram illustrating an electric field distribution of the signal transmission board according to the fifth embodiment; FIG.

FIG. 6 is a cross-sectional view for explaining a signal transmission board according to a sixth embodiment;

FIG. 7 is a cross-sectional view for describing a signal transmission board according to a seventh embodiment;

FIG. 8 is a sectional view for explaining a signal transmission board according to an eighth embodiment;

9A is a cross-sectional perspective view illustrating a signal transmission board according to a ninth embodiment, and FIG. 9B is a cross-sectional view illustrating an electric field distribution of the signal transmission board according to the ninth embodiment. FIG.

FIG. 10 is a cross-sectional view for explaining a signal transmission board according to a tenth embodiment;

FIG. 11 is a cross-sectional view for explaining a signal transmission board according to an eleventh embodiment;

FIG. 12A is a sectional perspective view for explaining a signal transmission board according to a twelfth embodiment, and FIG.
FIG. 9 is a cross-sectional view for describing an electric field distribution of the signal transmission board according to the embodiment.

FIGS. 13A and 13B are cross-sectional views for describing a modification of the twelfth embodiment; FIGS.

FIG. 14 is a sectional view for describing a signal transmission board according to a thirteenth embodiment;

FIG. 15 is a sectional view for explaining a signal transmission board according to a fourteenth embodiment;

FIG. 16A is a cross-sectional perspective view for explaining a signal transmission board according to a fifteenth embodiment, and FIG.
FIG. 9 is a cross-sectional view for describing an electric field distribution of the signal transmission board according to the embodiment.

FIG. 17 is a sectional view for describing a signal transmission board according to a sixteenth embodiment;

FIG. 18 is a sectional view for describing a signal transmission board according to a seventeenth embodiment;

FIG. 19 is a sectional view for describing a signal transmission board according to an eighteenth embodiment;

FIG. 20 is a sectional view for describing a signal transmission board according to a nineteenth embodiment;

[Explanation of symbols]

10: Dielectric substrate (ceramic substrate) 10a: First main surface 10b: Second main surface 12: Signal transmission line 14: Ground line 14a: Projecting portion 16, 16a, 16b: Back surface electrode 18, 20: Back surface groove 22: V-shaped groove 22a: slope 24, 24a, 24b: projection 26, 26a, 26b: slope 30: dielectric substrate (resin substrate) 30a: first main surface 30b: second main surface 34, 36, 38: ground line 100, 102, 106, 108, 110, 112, 1
14, 116, 118, 120, 122, 124, 12
6,128,130,132,134,136,13
8, 140, 142: signal transmission board

Claims (14)

[Claims] 1. A signal transmission board having a plurality of signal transmission lines on a first main surface of a dielectric substrate, wherein a portion of the dielectric substrate between the signal transmission lines extends along a direction in which the signal transmission path extends. A signal transmission board, wherein a ground line extending and extending from the signal transmission line is exposed and embedded in the first main surface. 2. The signal transmission board according to claim 1, wherein the exposed portion of the ground line protrudes above the first main surface. 3. The signal transmission board according to claim 1, further comprising: a back surface side groove in a portion corresponding to a back side of the signal transmission line in a second main surface which is a back surface of the dielectric substrate. A signal transmission board comprising a grounding back electrode in a side groove. 4. The signal transmission board according to claim 1, wherein a back surface side groove is provided in a portion corresponding to a back side between the signal transmission lines in a second main surface that is a back surface of the dielectric substrate. A signal transmission board comprising a back surface electrode for grounding in a back surface side groove. 5. A signal transmission board having a plurality of signal transmission lines on a first main surface of a dielectric substrate, wherein the first main surface portion between the signal transmission lines has a cross-sectional shape of V
A signal transmission board, comprising: a V-shaped groove extending in the direction in which the signal transmission line extends; and a ground line provided on a slope of the V-shaped groove. 6. The signal transmission board according to claim 5, wherein two V-shaped grooves are provided in a first main surface portion between the signal transmission lines, and the first main groove between the two V-shaped grooves is provided. A signal transmission board comprising: a protruding portion extending on the surface portion along the extending direction of the V-shaped groove and protruding; and a ground line being provided on a slope of the protruding portion. 7. The signal transmission board according to claim 5, further comprising a back surface side groove in a portion corresponding to the back side of the signal transmission line, of the second main surface that is the back surface of the dielectric substrate. A signal transmission board comprising a grounding back electrode in a side groove. 8. The signal transmission board according to claim 5, further comprising: a back surface side groove in a portion corresponding to a back side between the signal transmission lines in a second main surface that is a back surface of the dielectric substrate. A signal transmission board comprising a back surface electrode for grounding in a back surface side groove. 9. A signal transmission board comprising a plurality of signal transmission lines on a first main surface of a dielectric substrate, wherein the first main surface portion between the signal transmission lines extends in a direction in which the signal transmission lines extend. A signal transmission board comprising: a protruding portion extending along and protruding along a ground line on a slope of the protruding portion. 10. The signal transmission board according to claim 9, wherein a V-shaped groove having a V-shaped cross section is formed in a first main surface portion between the signal transmission line and the projection. A signal transmission board, which is provided so as to extend in the extending direction of the V-shaped groove, and is provided with a ground line on the slope of the V-shaped groove. 11. The signal transmission board according to claim 9, further comprising a back surface side groove in a portion corresponding to the back side of the signal transmission line, of the second main surface that is the back surface of the dielectric substrate. A signal transmission board comprising a grounding back electrode in a side groove. 12. The signal transmission board according to claim 9, further comprising a back surface side groove in a portion corresponding to a back side between the signal transmission lines, of a second main surface that is a back surface of the dielectric substrate, A signal transmission board comprising a back surface electrode for grounding in a back surface side groove. 13. A signal transmission board comprising a plurality of signal transmission lines on a first main surface of a dielectric substrate, wherein the second main surface, which is a back surface of the dielectric substrate, is located on the back side of the signal transmission line. A signal transmission board comprising: a back surface groove in a corresponding portion; and a back surface electrode for grounding in the back surface groove. 14. A signal transmission board having a plurality of signal transmission lines on a first main surface of a dielectric substrate, wherein a back side between the signal transmission lines of a second main surface that is a back surface of the dielectric substrate. A signal transmission board, comprising: a back surface side groove in a portion corresponding to (a), and a back surface electrode for grounding in the back surface side groove.