JP2003174304A - Transmission line board - Google Patents

Abstract

(57) [Problem] To provide a transmission line substrate capable of increasing the impedance value of a transmission line and accurately setting the impedance to a desired value. SOLUTION: A first transmission line 1a having a substantially wave-shaped pattern is formed on one side of a base 5a, and the first transmission line 1a having a substantially wave-shaped pattern is formed on the other side of the base 5a so as to be line-symmetric with the first transmission line 1a. Two transmission lines 2a are formed, and the first and second transmission lines 1a and 2a are continuously and three-dimensionally crossed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line board having a first transmission line and a second transmission line insulated from the first transmission line.

[0002]

2. Description of the Related Art In recent years, printed circuit boards used in electronic devices have been downsized in order to achieve high-speed electronic devices, and transmission lines formed on the printed circuit boards have been miniaturized and transmitted by the transmission lines. Signals tend to be faster.

When a signal is transmitted at high speed by using the transmission line which has been miniaturized as described above, impedance control for setting the impedance value of the transmission line to a desired value becomes important. That is, when impedance control is not accurately performed, high-speed signals cannot be stably transmitted, and electronic devices may not operate.

The impedance of the transmission line depends on the width and height of the transmission line, the distance between the transmission line and the ground layer, the dielectric constant of the insulating layer of the printed circuit board on which the transmission line is formed, and the like. Generally, it is inversely proportional to the cross-sectional area (width × height) of the transmission line and also inversely proportional to the dielectric constant of the substrate.

[0005]

However, the width and height of the transmission line that can be realized are limited by the manufacturing technique of the printed circuit board, and it is difficult to realize an impedance of a certain value or more. In particular, it is more difficult to increase the impedance value of a flexible substrate that requires the use of an insulating layer having a high dielectric constant such as polyimide.

Further, with the miniaturization of the transmission line, variations in the processing precision of the transmission line and the like have a great influence on the impedance value of the transmission line, and the impedance value of the transmission line must be accurately set to a desired value. Is getting harder.

It is an object of the present invention to provide a transmission line board which can increase the impedance value of the transmission line and can accurately set it to a desired value.

[0008]

[Means for Solving the Problems and Effects of the Invention] (1)
1st invention The transmission line board which concerns on 1st invention is a transmission line board in which the 1st transmission line and the 2nd transmission line insulated with respect to the 1st transmission line were formed, Comprising: The first and second transmission lines continuously and three-dimensionally intersect.

In the transmission line substrate according to the present invention, the first transmission line and the second transmission line insulated from the first transmission line are provided.
Of the first transmission line and the second transmission line, and the crossing interval of the first and second transmission lines. By increasing the values, the impedance values of the first and second transmission lines can be increased. Therefore, by adjusting the pattern spacing and the crossing spacing of the first and second transmission lines, the impedance value of the transmission line can be made higher and can be accurately set to a desired value.

(2) Second Invention A transmission line substrate according to a second invention is the structure of the transmission line substrate according to the first invention, wherein the first transmission line is a first transmission line and a second transmission line. The second transmission line is formed on one side of an insulating layer for insulating the transmission line, the second transmission line is formed on the other side of the insulating layer, and the first and second transmission lines are three-dimensionally intersected at a predetermined interval. To do.

In this case, since the first transmission line is formed on one side of the insulating layer and the second transmission line is formed on the other side of the insulating layer, the first and the third lines that three-dimensionally intersect at a predetermined interval. Two
The transmission line can be easily formed on the insulating layer.

(3) Third Invention A transmission line board according to a third invention is the structure of the transmission line board according to the first invention, wherein the first transmission line includes a first transmission line and a second transmission line. A plurality of first conductive portions formed on one side of the insulating layer for insulating the transmission line from each other, and a plurality of second conductive portions formed on the other side of the insulating layer, the second transmission The line includes a plurality of third conductive portions formed on the other side of the insulating layer and a plurality of fourth conductive portions formed on one side of the insulating layer, and the first and second conductive portions are , Electrically sequentially connected via a first connecting portion penetrating the insulating layer,
And the fourth conductive portion are electrically connected sequentially via the second connecting portion penetrating the insulating layer, and the first and second transmission lines intersect three-dimensionally at a predetermined interval.

In this case, a plurality of first conductive portions formed on one side of the insulating layer and a plurality of second conductive portions formed on the other side of the insulating layer make a first connection through the insulating layer. Electrically connected in sequence through the insulating layer, the plurality of third conductive portions formed on the other side of the insulating layer and the plurality of fourth conductive portions formed on one side of the insulating layer are insulating layers. The first and second transmission lines that are three-dimensionally spirally intersected can be easily formed because they are electrically sequentially connected through the second connecting portion that penetrates through.

(4) Fourth Invention A transmission line board according to a fourth invention is the transmission line board according to any one of the first to third inventions, wherein the third transmission line and the third transmission line are provided. And a fourth transmission line insulated from the line, wherein the first and second transmission lines are the first and second transmission lines.
The three and four transmission lines intersect three-dimensionally at intervals of
It is arranged in parallel to the first and second transmission lines and three-dimensionally intersects at a second interval different from the first interval.

In this case, the first and second transmission lines are the first
And the third and fourth transmission lines are three-dimensionally intersected at a second interval different from the first interval, and thus are transmitted by the first and second transmission lines. Crosstalk between the signal and the signal transmitted by the third and fourth transmission lines can be reduced.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A transmission line substrate according to each embodiment of the present invention will be described below with reference to the drawings.
1 is a plan view schematically showing a configuration of a transmission line board according to a first embodiment of the present invention, and FIG. 2 is a schematic view showing a sectional structure of the transmission line board shown in FIG. It is an A'sectional view.

The transmission line substrate 10a shown in FIGS. 1 and 2.
Is a flexible substrate, and includes a first transmission line 1a, a second transmission line 2a, a first coverlay 3a, a second coverlay 4a, and a base 5a. In addition, in FIG.
In order to facilitate the illustration, the second transmission line 2a arranged below the base 5a serving as a substrate is shown by a solid line, and the first cover lay 3a, the second cover lay 4a, and the base 5a have outer shapes. Only the solid line is shown.

The first transmission line 1a is formed on one side (the upper side in FIG. 2) of the base 5a which serves as an insulating layer, and the first coverlay 3a which serves as an insulating layer is formed on the first transmission line 1a.
Is formed. On the other hand, the second transmission line 2a is formed on the other side (lower side in FIG. 2) of the base 5a, and the second coverlay 4a serving as an insulating layer is formed on the second transmission line 2a. For example, the first and second transmission lines 1a and 2a
Is composed of a copper foil having a thickness of about 18 μm.
The cover lays 3a and 4a of the above are composed of an adhesive layer having a thickness of about 35 μm and a polyimide having a thickness of about 25 μm,
a is composed of an adhesive layer having a thickness of about 22 μm, polyimide having a thickness of about 25 μm, and an adhesive layer having a thickness of about 22 μm.

The structure of the transmission line board 10a is not particularly limited to the above example, and various modifications can be made. The materials of the first and second transmission lines 1a and 2a are not particularly limited to the above examples, other conductive materials may be used, and the first and second coverlays 3a and 4a and the base may be used. 5
The material and structure of a are not particularly limited to the above example, and other insulating materials may be used. In addition, the first and second transmission lines 1a and 2a, the first and second coverlays 3a and 4a.
Also, the thickness of the base 5a is not particularly limited to the above example, and various changes can be made.

The first and second transmission lines 1a and 2a have a line-symmetrical wiring pattern, and the first transmission line 1a is bent by about 45 degrees with respect to the straight line portion P1 and the straight line portion P1. The second transmission line 2a is composed of a substantially wave-shaped pattern in which the intersecting portions P2 are sequentially connected, and the second transmission line 2a is bent approximately 45 degrees with respect to the linear portion P3 arranged substantially parallel to the linear portion P1 and the linear portion P3. The cross-shaped portion P4 is sequentially connected to the cross-shaped portion P4.

With the above wiring pattern, the pattern width W
The straight line portion P1 and the straight line portion P3 having the pattern width W are arranged in parallel at a pattern interval S, and the crossing portion P3 and the crossing portion P
4 intersects with each other at about 90 degrees, and the first and second transmission lines 1
a and 2a are three-dimensionally intersected at an intersection interval L.

The transmission line board 10 constructed as described above.
In a, for example, a high speed signal is transmitted by one of the first and second transmission lines 1a and 2a, and the other is used as a ground line. In addition, the first and second transmission lines 1a, 2
The signal transmitted by a is not particularly limited to the above example, and a differential signal or the like may be transmitted by the first and second transmission lines 1a and 2a.

Next, the first and second transmission lines 1a and 2a
The influence of the pattern width W, the pattern interval S, and the crossing interval L on the impedance Z of will be described using Table 1 below. In Table 1, the unit of the impedance Z of the first and second transmission lines 1a and 2a is (Ω),
The unit of the pattern width W, the pattern interval S, and the intersection interval L is (mil).

[0024]

[Table 1]

Table 1 shows the first and second transmission lines 1a and 2
Impedance Z of a, pattern width W, pattern spacing S
And the relationship with the intersection distance L, and Examples 1 to 1 shown in Table 1
5 is the transmission line substrate 10a shown in FIG. 1 and FIG. 2 having the pattern width W, the pattern interval S, and the intersection interval L shown in Table 1. In Comparative Example 1, linear transmission lines having a pattern width W = 6 (mil) are formed on both sides of the base, and in Comparative Example 2, the pattern width W = 5 (mil) on one side of the base. 2) are formed with a pattern interval S = 19 (mil), and Comparative Examples 1 and 2 are two parallel transmission lines having no intersection. The same overlay is used in Examples 1 to 5 and Comparative Examples 1 and 2.

The impedance Z of Examples 1 to 5 is 90.
˜130 (Ω), and impedance Z of Comparative Example 1 =
It becomes about 1.5 to 2.17 times of 60 (Ω), and about 1.06 to 1.53 of the impedance Z = 85 (Ω) of Comparative Example 2.
Doubled. As a result, it was found that the impedance Z can be improved by intersecting the first and second transmission lines 1a and 2a with each other at a predetermined interval as in the first to fifth embodiments.

Further, the impedance Z of the fifth embodiment having the pattern width W = 10 (mil) is 90 (Ω), and the impedance Z of the first to fourth embodiments having the pattern width W = 6 (mil) is 98 to 130 ( Ω), and it was found that the impedance Z can be improved by reducing the pattern width W.

Further, the impedance Z of Example 1 with the pattern interval S = 4 (mil) is 100 (Ω), and the impedance Z of Example 3 with the pattern interval S = 9 (mil) is 110 (Ω). , Pattern interval S = 14 (mi
The impedance Z of Example 1 of 1) was 130 (Ω), and it was found that the impedance Z can be improved by increasing the pattern interval S.

The impedance Z of Example 2 with the crossing interval L = 45.5 (mil) is 98 (Ω), and the crossing interval L is
= 90 (mil), the impedance Z of Example 1 is 10
It became 0 (Ω), and it was found that the impedance Z can be improved by increasing the crossing interval L.

Next, the influence of the pattern width on the impedance of the transmission line will be described. The impedance Z ₀ of a general transmission line is approximately given by the following equation (STEPHEN H. HALL, et all: High-Speed Digital Syst
em Design, A Handbook of Interconnect Theory and D
See esign Practices, pp318).

Z ₀ = (μ ₀ ε ₀ / ε _e ) ^1/2 · (1 / C _a ) ... (1) C _a = 2πε ₀ / ln (8H / W + W / 4H) (2) ε _e = (Ε _r +1) / 2 + ((ε _r −1) / 2) · (1 + 12H / W) ^−1/2 + F −0.217 (ε _r −1) · (T / (WH) ^1/2 ) ... (3) F = 0.02 (ε _r −1) · (1-W / H) ² (4) where μ ₀ is the magnetic permeability of vacuum, and ε ₀ is the dielectric constant of vacuum, H is the distance between the transmission line and the ground layer, and T
Is the height of the transmission line, W is the pattern width of the transmission line, and ε _r is the dielectric constant of the base that serves as an insulating layer.

In the above equations (2) and (3), the distance H
Is larger than the coefficients of the pattern width W and the height T, and the variation of the distance H, that is, the variation of the thickness of the base greatly affects the value of the impedance Z ₀ . It can be seen that the variation in the pattern width W has little effect.

Therefore, also in the present embodiment, the variation of the pattern width W due to the production variation or the like does not affect the impedance Z of the first and second transmission lines 1a and 2a so much, so that the first and second transmission lines 1a are formed. , 2a, the impedance Z of the first and second transmission lines 1a, 2a can be increased without being significantly affected by the variation in the pattern width W. As a result, the first and second transmission lines 1
By adjusting the pattern width W of a and 2a, the impedance Z of the first and second transmission lines 1a and 2a can be set to a desired value with high accuracy and easily.

Further, in the present embodiment, the first transmission line 1a and the second transmission line 2a are formed so as to continuously and three-dimensionally intersect, so that the first and second transmission lines are formed. The value of the impedance Z of the first and second transmission lines 1a and 2a can be increased by increasing the pattern distance S of the first and second transmission lines 1a and 2a, and the distance between the intersections of the first and second transmission lines 1a and 2a can be increased. The value of the impedance Z of the first and second transmission lines 1a and 2a can also be increased by increasing L.

Therefore, the first and second transmission lines 1
By adjusting the pattern spacing S and the crossing spacing L of a and 2a, the impedance values of the first and second transmission lines 1a and 2a can be made higher and can be accurately set to desired values. You can As a result, the first
Also, noise generated in the signals transmitted by the second transmission lines 1a and 2a can be reduced, and the signals can be transmitted at a higher speed.

Further, in this embodiment, the first transmission line 1a is formed on one side of the base 5a, and the second transmission line 2a is formed on the other side of the base 5a. The transmission lines 1a and 2a can be easily formed on the base 5a.

Next, a transmission line board according to a second embodiment of the present invention will be described. FIG. 3 is a plan view schematically showing the structure of the transmission line board according to the second embodiment of the present invention, and FIG. 4 is a schematic view showing a sectional structure of the transmission line board shown in FIG. It is a B'sectional view.

The transmission line substrate 10b shown in FIGS. 3 and 4.
Is a flexible substrate, and includes a first transmission line 1b, a second transmission line 2b, a first coverlay 3b, a second coverlay 4b, and a base 5b.

The first transmission line 1b includes a plurality of first and second conductive portions D1 and D2 and a plurality of first via holes 6.
a and the first and second conductive parts D1 and D2 are
Similar to the first embodiment, it has a straight portion and an intersecting portion that is bent about 45 degrees with respect to the straight portion. The second transmission line 2a is composed of a plurality of third and fourth conductive portions D3, D4 and a plurality of second via holes 6b, and the third and fourth conductive portions D3, D4 are the first Similar to the embodiment, it has a straight portion and an intersection portion that is bent about 45 degrees with respect to the straight portion. In FIG. 3, in order to facilitate the illustration,
The second conductive portion D2 and the third conductive portion D3, which are arranged under the base 5b serving as a substrate, are shown by solid lines, and
Only the outer shapes of the first coverlay 3b, the second coverlay 4b and the base 5b are shown by solid lines.

A plurality of first conductive portions D1 are formed on one side (upper side in FIG. 4) of the base 5b which serves as an insulating layer, and a plurality of second conductive portions D1 are formed on the other side (lower side in FIG. 4) of the base 5b. The portion D2 is formed, and the first and second conductive portions D1 and D are formed.
2 are sequentially connected through the via hole 6a which is a first connecting portion penetrating the base 5b, and the first transmission line 1b is formed in a substantially spiral shape.

On the other hand, a plurality of third conductive portions D3 are formed on the other side of the base 5b, a plurality of fourth conductive portions D4 are formed on one side of the base 5b, and the third and fourth conductive portions D are formed.
3, D4 are sequentially connected via a via hole 6b which is a second connecting portion penetrating the base 5b, and has a substantially spiral second shape.
The transmission line 2b is formed.

First and second via holes 6a, 6b
Is made of, for example, copper, the first via hole 6a electrically connects the first and second conductive portions D1 and D2, and
Of the via hole 6b of the third and fourth conductive portions D3, D4.
To be electrically connected. The material of the first and second via holes 6a and 6b is not particularly limited to the above example, and other conductive materials may be used.

Further, the first coverlay 3b serving as an insulating layer is formed on the first and third conductive portions D1 and D3, and the second coverlay 3b is formed.
And the 2nd coverlay 4b used as an insulating layer is formed on the 4th electric conduction parts D1 and D3. In addition, except the above points,
This is the same as in the first embodiment.

As described above, the first to fourth conductive portions D are formed.
By sequentially connecting 1 to D4 via the first and second via holes 6a and 6b, the first and second transmission lines 1b and 2b that are three-dimensionally crossed in a spiral shape are formed.
Similar to the embodiment described above, the first and second transmission lines 1b and 2b having the pattern width W, the pattern interval S and the intersecting interval L can be formed.

With the above structure, the same effects as those of the first embodiment can be obtained in this embodiment as well, and the first and second transmission lines 1b and 2b which are three-dimensionally intersected in a spiral shape. Can be easily formed on the transmission line substrate 10b.

Next, a transmission line board according to a third embodiment of the present invention will be described. FIG. 5 is a plan view schematically showing the configuration of the transmission line board according to the third embodiment of the present invention.

The transmission line substrate 10c shown in FIG. 5 is a flexible substrate and includes a first transmission line 1c, a second transmission line 2c, a third transmission line 1d, a fourth transmission line 2d and a first cover. A ray 3c and the like are provided. The third embodiment also has a base and a second coverlay as in the first embodiment, but in FIG. Located in the second
The transmission line 2c and the fourth transmission line 2d are shown by solid lines, and only the outer shapes of the first coverlay 3c, the second coverlay and the base are shown by solid lines.

The first and second transmission lines 1c and 2c and the third
The fourth and fourth transmission lines 1d and 2d are respectively formed in the same manner as the first and second transmission lines 1a and 2a of the first embodiment, and the first and second transmission lines 1c and 2c.
Is set to L1 and the crossing interval of the third and fourth transmission lines 1d and 2d is set to L2 (> L1).

With the above configuration, in this embodiment, the first and second transmission lines 1c and 2c and the third and fourth transmission lines 1d and 2d are similar to those in the first embodiment. In addition to being able to obtain the effect, the first and second transmission lines 1c and 2c intersect each other at the crossing interval L1, and the third and fourth transmission lines 1d and 2d at the crossing interval L2 different from the crossing interval L1. Since they intersect, the first and second transmission lines 1c and 2c and the third and fourth transmission lines 1
Crosstalk between signals transmitted by d and 2d can be reduced.

The relationship between the crossing interval L1 and the crossing interval L2 is not only different, but also the number of crossings n (= L0) of the first and second transmission lines 1c and 2c with respect to the predetermined distance L0.
/ L1) and the number of intersections m (= L0 / L2) of the third and fourth transmission lines 1d and 2d (= n−m, n = 10, m = 9 in the example shown in FIG. 5) It is preferably 1. In this case, crosstalk between the signals transmitted by the first and second transmission lines 1c and 2c and the third and fourth transmission lines 1d and 2d can be further reduced.

In the above description, the transmission lines are three-dimensionally intersected by alternately forming the straight line portions and the crossing portions, but the present invention is not limited to this example, and the straight line portions may be omitted. It is also possible to form a triangular wave pattern or a curved pattern such as a sine wave from only this. Further, the angle between the straight line portion and the intersecting portion is not particularly limited to 45 degrees described above, and the intersecting portion may be formed using other angles such as 30 degrees and 60 degrees.

Further, although the pair of transmission lines are formed by using the conductor layers on both sides of the base, the present invention is not limited to this example and various modifications can be made. You may make it form three or more pairs of transmission lines in the principal surface direction. Further, the conductor layer may be four layers or more to form two or more pair of transmission lines in the thickness direction of the substrate. In this case, as an insulating layer between one pair of transmission lines and another pair of transmission lines. Can be made of polyimide, glass epoxy resin FR4, an insulating-treated aluminum substrate, or the like.

In each of the above embodiments, an example in which the present invention is applied to a flexible substrate has been described, but the present invention is not particularly limited to this example, and other printed substrates such as a hard printed circuit board and a flex-rigid printed circuit board, an IC. (Integrated circuit)
The present invention can be similarly applied to internal wiring and the like.

In each of the above embodiments, an example in which only the transmission line is provided has been described. However, electrical components such as resistors, capacitors, ICs, etc. may be provided on each substrate together with the transmission line. In addition to the transmission line of the invention, a normal linear transmission line may be provided.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing a configuration of a transmission line board according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA ′ schematically showing the sectional structure of the transmission line substrate shown in FIG.

FIG. 3 is a plan view schematically showing a configuration of a transmission line board according to a second embodiment of the present invention.

4 is a BB ′ cross-sectional view schematically showing a cross-sectional structure of the transmission line substrate shown in FIG.

FIG. 5 is a plan view schematically showing a configuration of a transmission line board according to a third embodiment of the present invention.

[Explanation of symbols]

1a to 1c First transmission line 1d Third transmission line 2a to 2c Second transmission line 2d fourth transmission line 3a to 3c First cover lay 4a, 4b second coverlay 5a, 5b base 6a, 6b via hole 10a to 10c Transmission line substrate P1, P3 Straight section P2, P4 intersection D1 First conductive part D2 Second conductive part D3 Third conductive part D4 Fourth conductive part

Claims (4)

[Claims] 1. A transmission line substrate having a first transmission line and a second transmission line insulated from the first transmission line, wherein the first and second transmission lines are A transmission line substrate characterized by continuous three-dimensional intersections. 2. The first transmission line is formed on one side of an insulating layer for insulating the first transmission line and the second transmission line, and the second transmission line is The transmission line substrate according to claim 1, wherein the transmission line substrate is formed on the other side of the insulating layer, and the first and second transmission lines intersect three-dimensionally at a predetermined interval. 3. The first transmission line, a plurality of first conductive portions formed on one side of an insulating layer for insulating the first transmission line and the second transmission line, A plurality of second conductive portions formed on the other side of the insulating layer, wherein the second transmission line includes a plurality of third conductive portions formed on the other side of the insulating layer; A plurality of fourth conductive portions formed on one side of the layer, wherein the first and second conductive portions are electrically sequentially connected via a first connecting portion penetrating the insulating layer. The third and fourth conductive parts are electrically sequentially connected via a second connection part that penetrates the insulating layer, and the first and second transmission lines are three-dimensionally spaced at predetermined intervals. The transmission line board according to claim 1, wherein the transmission line boards intersect with each other. 4. A third transmission line and a fourth transmission line insulated from the third transmission line, wherein the first and second transmission lines are three-dimensionally spaced at a first distance. Crossing, the third and fourth transmission lines are arranged in parallel to the first and second transmission lines, and three-dimensionally at a second interval different from the first interval. The transmission line board according to claim 1, wherein the transmission line boards intersect with each other.