JP2024005575A - Printed-circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed-circuit board that can effectively reduce far-end crosstalk.

SOLUTION: A printed-circuit board comprises an insulator, first wiring, second wiring, and third wiring. The first wiring extends in a first direction on a first surface of the insulator. The second wiring extends in the first direction in parallel with the first wiring on the first surface of the insulator. The third wiring is located between the first wiring and the second wiring on the first surface of the insulator, and extends in the first direction. The third wiring is in a meander shape meandering periodically.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to printed wiring boards.

There is a technique for transmitting signals using microstrip wiring provided on the surface of an insulator (for example, Patent Document 1). Conventionally, in this technology, when transmitting signals using multiple parallel wires, it was necessary to increase the distance between the two wires or to provide a guard wire with a ground potential between the two wires. In this way, near-end crosstalk and far-end crosstalk occurring between two wires are reduced.

Japanese Patent Application Publication No. 2008-71971

In recent years, printed wiring boards provided with microstrip wiring have come to be used for signal transmission in a high frequency band of several tens of GHz. In such a high frequency band, there is a problem that far-end crosstalk cannot be sufficiently reduced even if the conventional crosstalk reduction method described above is applied.

A printed wiring board according to one aspect of the present disclosure includes an insulator, a first wiring extending in a first direction on a first surface of the insulator, and a first wiring on the first surface of the insulator. a second wiring extending in the first direction in parallel; and a second wiring located between the first wiring and the second wiring on the first surface of the insulator and extending in the first direction. and a third wiring. The third wiring has a periodically meandering meandering shape.

According to the content of the present disclosure, far-end crosstalk can be effectively reduced.

FIG. 3 is a diagram showing the configuration of a printed wiring board. 2 is a diagram showing a cross section taken along line AA in FIG. 1. FIG. FIG. 3 is a diagram showing the configuration of guard wiring. 3 is a diagram showing the configuration of a printed wiring board according to Comparative Example 1. FIG. 3 is a diagram showing the configuration of a printed wiring board according to Comparative Example 2. FIG. FIG. 3 is a diagram showing lines of electric force occurring in common mode. FIG. 3 is a diagram showing lines of electric force that occur in differential mode. FIG. 7 is a diagram showing an example of relative dielectric constants ε _re and ε _ro depending on the periodic structure of guard wiring. FIG. 3 is a diagram showing parameters used in simulation. FIG. 3 is a diagram showing parameters and configurations used in simulation. It is a figure which shows the simulation result of the far end crosstalk when width Ww is 0.7 mm and interval G1 is 0.13 mm. It is a figure which shows the simulation result of the far end crosstalk when width Ww is 0.65 mm and interval G1 is 0.155 mm. It is a figure which shows the simulation result of the far end crosstalk when width Ww is 0.6 mm and interval G1 is 0.18 mm. It is a figure which shows the simulation result of the far end crosstalk when width Ww is 0.55 mm and interval G1 is 0.205 mm. It is a figure which shows the simulation result of the far end crosstalk when width Ww is 0.5 mm and the space|interval G1 is 0.23 mm. It is a figure which shows the simulation result of far end crosstalk when width Ww is 0.45 mm and interval G1 is 0.255 mm. 17 is a diagram showing the effect of reducing far-end crosstalk when each periodic structure is adopted in the simulations of FIGS. 11 to 16. FIG. 7 is a diagram illustrating the effect of reducing far-end crosstalk when guard wiring is used in comparison with Comparative Example 1 and Comparative Example 2. FIG. FIG. 7 is a diagram showing relative dielectric constants ε _re and ε _ro in comparison with Comparative Example 1 and Comparative Example 2 when guard wiring is used. FIG. 4 is a diagram illustrating the influence of the connection manner of terminating resistors at both ends of the guard wiring on far-end crosstalk.

Hereinafter, embodiments will be described based on the drawings. However, for convenience of explanation, each figure referred to below shows only the main members necessary for explaining the embodiment in a simplified manner. Therefore, the printed wiring board 1 of the present disclosure may include any constituent members not shown in the respective figures referred to. Furthermore, the dimensions of the members in each figure do not faithfully represent the dimensions and dimensional ratios of the actual constituent members.

[Configuration of printed wiring board]
The configuration of a printed wiring board 1 according to this embodiment will be described with reference to FIGS. 1 and 2.
In the following, the orientation of each part of the printed wiring board 1 will be explained using an XYZ orthogonal coordinate system in which the thickness direction of the printed wiring board 1 is the Z direction. Further, the extending direction of first wiring 10 and second wiring 20, which will be described later, provided on printed wiring board 1 is defined as the X direction, and the direction perpendicular to the X direction and the Z direction is defined as the Y direction. FIG. 1 shows a part of a printed wiring board 1 viewed from above in the +Z direction. Further, FIG. 2 shows a part of a cross section of the printed wiring board 1 of FIG. 1 taken along line AA and perpendicular to the Y direction. Hereinafter, the surface facing the +Z direction of each layer constituting the printed wiring board 1 will also be referred to as the "upper surface", and the surface facing the −Z direction will also be referred to as the "lower surface". Further, the Z direction is also referred to as the "thickness direction." Furthermore, viewing the printed wiring board 1 from the Z direction with some of the components transmitted through it is referred to as "plane perspective."

As shown in FIGS. 1 and 2, the printed wiring board 1 includes an insulator 40, a wiring L1, a wiring L2, and a guard wiring 30 (third wiring) provided on the first surface 41 (upper surface) of the insulator 40. and a pad electrode 60, a GND layer 50 (ground conductor) provided on the second surface 42 (lower surface) opposite to the first surface 41 of the insulator 40, and a resistor mounted on the first surface 41. It includes an element 80 and the like. The wiring L1, the wiring L2, and the GND layer 50 constitute a microstrip line type signal transmission path. Other wiring or circuit elements for signal transmission are connected to wiring ends p1 and p2 of the wiring L1 and wiring ends p3 and p4 of the wiring L2. Further, the printed wiring board 1 may further include another insulator or conductor layer on the −Z direction side of the insulator 40 in FIG.

The insulator 40 is a flat member parallel to the XY plane. The material of the insulator 40 is not particularly limited as long as it has insulation properties. Examples of the material of the insulator 40 include organic resins such as epoxy resin, bismaleimide-triazine resin, polyphenylene ether (PPE) resin, polyimide resin, and liquid crystal polymer. Further, a reinforcing material such as glass cloth may be included in these organic resins. The insulator 40 may be formed by pressurizing and heating a prepreg (a member made by impregnating a reinforcing material such as glass cloth with a resin and semi-curing it) to melt it and then harden it. The thickness of the insulator 40 may be, for example, approximately several tens of μm to several hundred μm.

The wiring L1 includes a linear first wiring 10 extending in the X direction (first direction) on the first surface 41 of the insulator 40, and lead wiring 11 extending from both ends of the first wiring 10.
The wiring L2 includes a linear second wiring 20 extending in the X direction parallel to the first wiring 10 on the first surface 41 of the insulator 40, and a routing wiring 21 extending from both ends of the second wiring 20. have The second wiring 20 is parallel to the first wiring 10.

Guard wiring 30 is located between first wiring 10 and second wiring 20 on first surface 41 of insulator 40 . The guard wiring 30 extends in the X direction while exhibiting a periodically meandering meander shape (forming a meander shape). The extension range of the guard wiring 30 in the X direction is approximately equal to the extension range of the first wiring 10 and the second wiring 20. However, the invention is not limited to this, and the guard wiring 30 may be longer than the first wiring 10 and the second wiring 20 in the X direction, or may be shorter than the first wiring 10 and the second wiring 20. The end of the guard wiring 30 in the -X direction is a terminal 34, and the end in the +X direction is a terminal 35.

One pad electrode 60 is provided on the first surface 41 of the insulator 40 on the -X direction side of the terminal 34 of the guard wiring 30 and on the +X direction side of the terminal 35. A resistance element 80 can be mounted between the terminal 34 and the pad electrode 60 and between the terminal 35 and the pad electrode 60. Furthermore, a mode in which the terminal 34 and the pad electrode 60 and between the terminal 35 and the pad electrode 60 are electrically connected without using the resistance element 80 (a mode in which they are short-circuited) is very good. Alternatively, the terminal 34 and the pad electrode 60 and the terminal 35 and the pad electrode 60 may not be electrically connected (open). FIG. 1 exemplifies a mode in which a resistance element 80 is mounted between the terminal 34 and the pad electrode 60, and the terminal 35 and the pad electrode 60 are not electrically connected.

The materials of the wiring L1, the wiring L2, the guard wiring 30, and the pad electrode 60 are not particularly limited as long as they have conductivity. For example, the material of the wiring L1, the wiring L2, the guard wiring 30, and the pad electrode 60 may be copper. Copper may be formed by electroless plating or electrolytic plating, or may be rolled copper foil. Alternatively, the structure may be such that copper formed by plating is laminated on rolled copper foil. The thickness of the wiring L1, the wiring L2, the guard wiring 30, and the pad electrode 60 may be, for example, about several μm to several tens of μm. The method of forming the wiring L1, the wiring L2, the guard wiring 30, and the pad electrode 60 on the first surface 41 of the insulator 40 is not particularly limited, but for example, a combination of electrolytic panel plating and subtractive method, or A method such as MSAP (Modified Semi-Additive Process) may also be used. Further, even if the wiring L1, the wiring L2, the portions of the guard wiring 30 excluding the terminals 34, and the exposed surface of the first surface 41 of the insulator 40 are covered with an insulating film (solder resist, etc.), good.

As shown in FIG. 2, a GND layer 50 having a ground potential is provided on the second surface 42 of the insulator 40. The GND layer 50 is provided in a range overlapping with the wiring L1, the wiring L2, and the guard wiring 30 when viewed from above. The GND layer 50 may have a solid shape, for example. The material of the GND layer 50 is not particularly limited as long as it has conductivity, and may be copper, for example.

As shown in FIG. 2, the pad electrode 60 is electrically connected to the GND layer 50 via a via 70 that penetrates the insulator 40 in the thickness direction. The via 70 is made of a conductor that fills a via pilot hole that penetrates the insulator 40. The via 70 is formed, for example, by electroplating the insulator 40 with a via pilot hole formed therein. The material of the via 70 may be copper, for example. When the pad electrode 60 is electrically connected to the terminal 34 or the terminal 35 of the guard wiring 30 via the resistance element 80 or directly without the resistance element 80, the terminal 34 or the terminal 35 is , are electrically connected to the GND layer 50 via the pad electrode 60 and the via 70.

Next, the detailed configuration of the guard wiring 30 will be described with reference to FIG. 3.
As described above, the guard wiring 30 has a periodically meandering meander shape. Specifically, the guard wiring 30 has a shape in which first portions 31 and second portions 32 are connected to each other so as to be periodically and alternately lined up in the X direction. Among these, the distance between the first portion 31 and the first wiring 10 in the Y direction (second direction) is shorter than the distance between the first portion 31 and the second wiring 20 . Further, the distance between the second portion 32 and the second wiring 20 in the Y direction is shorter than the distance between the second portion 32 and the first wiring 10 . The guard wiring 30 has a third portion 33 that connects the first portion 31 and the second portion 32 and extends in the Y direction. The position of the end of the third portion 33 on the +Y direction side is flush with the position of the end of the first portion 31 on the +Y direction side. The position of the end of the third portion 33 on the −Y direction side is flush with the position of the end of the second portion 32 on the −Y direction side.

In this embodiment, the first portion 31, the second portion 32, and the third portion 33 are rectangles with each side parallel to the X direction or the Y direction. However, the corners of the rectangle or the corners of the connection between the first portion 31 or the second portion 32 and the third portion 33 may be rounded. Alternatively, the sides of the rectangle may be connected across a side that is inclined with respect to the side (for example, a side forming an angle of 45°). The side on the −X direction side (parallel to the Y direction) of the first portion 31 is the side on the +X direction side (parallel to the Y direction) of the third portion 33 located on the −X direction side of the first portion 31. (Nabe) is connected. The side on the +X direction side (parallel to the Y direction) of the first portion 31 is the −X side side (parallel to the Y direction) of the third portion 33 located on the +X direction side of the first portion 31. connected to the edges). The side of the second portion 32 on the −X direction side (the side parallel to the Y direction) is connected to the side of the third portion 33 located on the −X direction side of the second portion 32 on the +X direction side. The side of the second portion 32 on the +X direction side (the side parallel to the Y direction) is connected to the side of the third portion 33 located on the +X direction side of the second portion 32 on the −X direction side. In FIG. 3, the first portion 31, the second portion 32, and the third portion 33 are depicted separately, but in reality, the first portion 31, the second portion 32, and the third portion 33 are integrally connected. ing.

The guard wiring 30 has a shape in which a unit structure U consisting of a set of third portion 33, first portion 31, third portion 33, and second portion 32 adjacent to each other in the X direction is repeatedly arranged in the X direction. The length of the unit structure U in the X direction (repetition period in the X direction) is hereinafter referred to as 2P. Further, the total length of the adjacent third portion 33 and first portion 31 in the X direction is P, and the total length of the adjacent third portion 33 and second portion 32 in the X direction is P. be. Further, in this embodiment, the lengths of the first portion 31, the second portion 32, and the third portion 33 in the X direction are all P/2. By setting the length P to a value as small as possible, the influence of the guard wiring 30 on the transmission of high-frequency signals in the wiring L1 and the wiring L2 can be reduced. For example, if the minimum wiring width and the minimum wiring interval on the printed wiring board 1 are both 0.1 mm, the lengths of the first portion 31, the second portion 32, and the third portion 33 in the X direction are all 0.1 mm. The length P may be 0.1 mm, and the length P may be 0.2 mm.
Note that in the X direction, the lengths of the first portion 31 and the second portion 32 and the length of the third portion 33 are not necessarily the same, and the length of the third portion 33 is aP, and the length of the first portion 32 is 31 and the second portion 32 may have a length of (1-a)P. However, a is a constant satisfying 0<a<1/2 or 1/2<a<1.

As shown in FIG. 3, the width of the first wiring 10 and the second wiring 20 in the Y direction is a wiring width W. In other words, the wiring width W is the width of each of the first wiring 10 and the second wiring 20 in a short direction. Further, the distance between the first wiring 10 and the second wiring 20 in the Y direction is a distance G. In other words, the interval G is the distance between the edge of the first wiring 10 on the second wiring 20 side and the edge of the second wiring 20 on the first wiring 10 side when the first wiring 10 and the second wiring 20 are arranged in parallel. This refers to the distance between the edge and the edge. In addition, the distance between the first wiring 10 and the guard wiring 30 and the distance between the second wiring 20 and the guard wiring 30 in the Y direction are equal to each other and are the interval G1. In FIG. 3, the interval G1 is shown at two locations. The first interval G1 is the distance between the edge of the first wiring 10 on the guard wiring 30 side and the edge of the first portion 31 of the guard wiring 30 on the first wiring 10 side. This is the portion showing the shortest distance between the first wiring 10 and the guard wiring 30. The second interval G1 is the distance between the edge of the second wiring 20 on the guard wiring 30 side and the edge of the second portion 32 of the guard wiring 30 on the second wiring 20 side. This is the portion showing the shortest distance between the second wiring 20 and the guard wiring 30. Although the expression "predetermined width" is used for the wiring width W, the wiring width W can be, for example, 1/5 or more and 1/2 or less when the interval G is 1. Further, the width of the third portion 33 in the Y direction (the width of the guard wiring 30 in the Y direction) is the width Ww. The width Ww is the length of the guard wiring 30 along the lateral direction of the first wiring 10 and the second wiring 20. Here, along the lateral direction refers to the length in the direction perpendicular to the longitudinal direction of the first wiring 10 and the second wiring 20. The width Ww is larger than the wiring width W of the first wiring 10 and the second wiring 20. Further, the width of the first portion 31 and the width of the second portion 32 in the Y direction are equal to each other and have a width Wn. The width Wn is smaller than the width Ww.

In this way, by providing the guard wiring 30 having a periodic meander shape between the first wiring 10 and the second wiring 20, far-end crosstalk between the first wiring 10 and the second wiring 20 can be effectively reduced. can be reduced to Here, far-end crosstalk refers to a signal transmitted through one of the first wiring 10 and the second wiring 20 when the signal transmission directions in the two parallel first wiring 10 and second wiring 20 are the same. is said to combine with the signal transmitted through the other side. In the following, far-end crosstalk occurs when a signal input from the -X direction side (wiring end p1 side) of the first wiring 10 is coupled to a signal on the +X direction side (wiring end p4 side) of the second wiring 20. Let the size of be S ₄₁ .

また、以下では、次式（３）で与えられるΔｋを用いて説明する場合がある。Δｋは、式（２）の右辺の分子の一部である。

The far-end crosstalk _S41 is given by the following equation (1), where l is the wiring length of the first wiring 10 and the second wiring 20.
S ₄₁ =-jΔKl…(1)
Here, ΔK is given by the following equation (2).

Further, below, the explanation may be made using Δk given by the following equation (3). Δk is a part of the numerator on the right side of equation (2).

In formula (2), ε _re is the effective dielectric constant around the first wiring 10 and the second wiring 20 in the common mode, and ε _ro is the effective dielectric constant around the first wiring 10 and the second wiring 20 in the differential mode. where f is the frequency of the transmitted signal and c is the speed of light in vacuum. As can be seen from equations (1) and (2), far-end crosstalk S ₄₁ is proportional to the absolute value of the difference between the square root of ε _re and the square root of ε _ro (absolute value of Δk in equation (2)). do. Therefore, by bringing the effective relative permittivity ε _re in the common mode and the effective relative permittivity ε _ro in the differential mode close to each other (ideally, by making them match), far-end crosstalk S ₄₁ can be reduced. can do.

By providing the guard wiring 30 having a periodic meander shape as in this embodiment, printed wiring board 1a according to Comparative Example 1 shown in FIG. 4 and printed wiring board 1b according to Comparative Example 2 shown in FIG. It is possible to reduce far-end crosstalk _S41 .
Here, the printed wiring board 1a according to Comparative Example 1 shown in FIG. 4 does not have a guard wiring between the first wiring 10 and the second wiring 20 extending in the X direction. Further, the first wiring 10 and the second wiring 20 are arranged at an interval three times the width of each wiring in the Y direction.
The printed wiring board 1b according to Comparative Example 2 shown in FIG. (not included) is provided with normal wiring 90.

The above-mentioned common mode is one of two types of propagation modes when a signal is propagated to the far end side (+X direction side) in the first wiring 10 and the second wiring 20. This is a mode in which signals of the same phase flow through the wiring 20 and lines of electric force are generated between the first wiring 10 and the GND layer 50. On the other hand, the differential mode is one of the above two types of propagation modes, in which signals of opposite phases flow through the first wiring 10 and the second wiring 20, and the first wiring 10, the second wiring 20, and the first This is a mode in which electric lines of force are generated between the wiring 10 and the GND layer 50.

FIG. 6 is a diagram showing lines of electric force generated around the first wiring 10 and the second wiring 20 in the common mode.
FIG. 7 is a diagram showing lines of electric force generated around the first wiring 10 and the second wiring 20 in the differential mode.
6 and 7 show lines of electric force in a structure in which the guard wiring 30 is omitted (corresponding to the structure of Comparative Example 1).
In the case of microstrip wiring, the first wiring 10 and the second wiring 20 are located at the boundary between the insulator 40 (dielectric) and air, so the first wiring 10 and the second wiring 20 are on the GND layer 50 side. The relative permittivity (relative permittivity of the insulator 40: 3.35 here) on the side (-Z direction) is different from the relative permittivity (relative permittivity of air) on the side opposite to the GND layer 50 (+Z direction side). Dielectric constant: Different from 1).
As shown in FIG. 6, in the common mode, lines of electric force mainly occur between the first wiring 10 and the second wiring 20 and the GND layer 50, so the effective relative permittivity ε _re is The value is relatively close to the dielectric constant of the body 40, which is 3.35. On the other hand, as shown in FIG. 7, in the differential mode, lines of electric force are generated between the first wiring 10 and the second wiring 20, the first wiring 10 and the GND layer 50, and the second wiring 10 and the GND layer 50. , the proportion of electric lines of force passing through the air increases compared to common mode. Therefore, the effective relative permittivity ε _ro in the differential mode is smaller than the effective relative permittivity ε _re in the common mode.
As a result, in microstrip wiring, a difference occurs between the relative permittivity ε _re and the relative permittivity ε _ro , and depending on this difference, the far-end crosstalk shown in equations (1) and (2) above is S ₄₁ occurs.

Note that, depending on the difference in effective dielectric constant, a difference occurs in signal propagation delay time. Therefore, the relative dielectric constant can be derived from the propagation delay time. Specifically, the relative permittivity ε _re and the relative _permittivity ε _ro are derived from the following equations (4) and (5), where the common mode propagation delay time is t de and the differential mode propagation delay time is t _do . be able to.
ε _re = (ct _de /l) ² … (4)
ε _ro = (ct _do /l) ² …(5)

By providing the meander-shaped guard wiring 30 between the first wiring 10 and the second wiring 20, the effective dielectric constant ε _re of the common mode approaches the effective dielectric constant ε _ro of the differential mode. As such, the distribution of electric lines of force shown in FIGS. 6 and 7 can be changed. This is because in the common mode, the lines of electric force mainly pass through the inside of the insulator 40 as shown in Figure 6, so even if the distribution of the lines of electric force changes, the effective relative permittivity ε _re changes. On the other hand, in differential mode, as shown in Figure 7, the lines of electric force pass through more layers of air, which changes the distribution of the lines of electric force, reducing the amount of lines of electric force passing through the layer of air. This is because the ratio between the amount of lines of electric force passing through the inside of the insulator 40 tends to change, and the effective relative permittivity ε _ro tends to change. In addition, the distribution of electric lines of force can be further controlled by adjusting the width Ww and width Wn of the guard wiring 30. By adjusting the width Ww and width Wn so that the relative permittivity ε _re approaches the relative permittivity ε _ro , Δk shown in equation (3), that is, ΔK in equation (2), can be further reduced. As a result, the far-end crosstalk _S41 in equation (1) can be further reduced.

FIG. 8 is a diagram showing an example of relative dielectric constants ε _re and ε _ro depending on the periodic structure of the guard wiring 30.
“Periodic structure 21,” “periodic structure 13,” and “periodic structure 1” in FIG. 8 represent a certain periodic structure of guard wiring 30. Specifically, these three periodic structures have different combinations of width Ww and width Wn. The widths Ww and Wn of each of the "periodic structure 21", "periodic structure 13", and "periodic structure 1" will be described later.

As shown in FIG. 8, by changing the combination of the width Ww and the width Wn of the guard wiring 30, the effective relative dielectric constant ε _ro in the differential mode (broken line graph in FIG. The relative dielectric constant ε _r (solid line graph in FIG. 8) can be approached.

From the graph in FIG. 8, in a periodic structure in which an appropriate combination of width Ww and width Wn is selected, the effective relative permittivity ε _re in the common mode and the effective relative permittivity ε _ro in the differential mode are set to 0. be able to. Therefore, by providing the guard wiring 30 with this appropriate periodic structure, Δk shown in equation (3), that is, ΔK shown in equation (2), becomes 0, eliminating the far-end crosstalk S ₄₁ shown in equation (1). be able to. Furthermore, even if the wiring structure does not completely match the ideal periodic structure described above, far-end crosstalk S ₄₁ can be effectively reduced by making the widths Ww and Wn closer to the ideal wiring structure. .

With reference to FIGS. 9 to 16, simulation results of far-end crosstalk when the periodic structure (width Ww and width Wn) of the guard wiring 30 is changed will be described.
9 and 10 show the preconditions used in the simulation. In the simulation, the wiring width W of the first wiring 10 and the second wiring 20 was set to 0.32 mm, and the interval G between the first wiring 10 and the second wiring 20 was set to 0.96 mm. Therefore, the interval G is three times the wiring width W. Further, the interval G1 was set to a value satisfying G1=(G-Ww)/2. Further, it is assumed that the first surface 41 side of the insulator 40 is covered with a solder resist, and the relative permittivity, dielectric loss tangent, and thickness of the solder resist and the insulator 40 are as shown in FIGS. 9 and 10. did. Further, the material of the first wiring 10, the second wiring 20, the guard wiring 30, and the GND layer 50 was copper, and the thicknesses were set as shown in FIGS. 9 and 10. Further, the resistance value of the resistance element 80 at both ends of the guard wiring 30 (between the terminal 34 and the pad electrode 60 and between the terminal 35 and the pad electrode 60) is the same value as the characteristic impedance Z _p of the guard wiring 30. And so.

FIG. 11 shows simulation results of far-end crosstalk when the width Ww is 0.7 mm and the interval G1 is 0.13 mm. The simulation was performed by changing the width Wn of the first portion 31 and the second portion 32 of the guard wiring 30 from 0.1 mm to 0.6 mm in 0.05 mm increments, and these were sequentially changed to "periodic structure 1" to "periodic structure 11". ”. In addition, simulations were also performed for a configuration in which the width Wn was 0.7 mm, that is, a configuration in which a straight normal wiring 90 without a periodic structure was provided as in Comparative Example 2 in FIG. (described as “normal wiring”). FIG. 11 shows, for each level of width Wn, the characteristic impedance Z _p (Ω) of the guard wiring 30, the characteristic impedance Z ₀ (Ω) of the first wiring 10 and the second wiring 20, and the effective relative permittivity in the common mode. The effective dielectric constant _{ε ro in} the differential mode, and Δk in equation (3) (a quantity proportional to far-end crosstalk S ₄₁ ) are shown.

As shown in FIG. 11, for "Periodic Structure 1" to "Periodic Structure 11", the absolute value of Δk is smaller than that of "normal wiring", and simulation results that can reduce far-end crosstalk _S41 are obtained. Ta. Among these, in "periodic structure 7" to "periodic structure 9" (range R1 in FIG. 11) where Δk is 0 or more and 0.009 or less, far-end crosstalk S ₄₁ can be brought almost to zero. Note that when Δk takes a negative value, it is difficult to achieve the effect of reducing far-end crosstalk S ₄₁ on the high frequency side, but it is possible to effectively reduce far-end crosstalk S ₄₁ on the low frequency side. .

FIG. 12 shows simulation results of far-end crosstalk when the width Ww is 0.65 mm and the interval G1 is 0.155 mm. The simulation was performed by changing the width Wn of the first portion 31 and the second portion 32 of the guard wiring 30 from 0.1 mm to 0.55 mm in 0.05 mm increments, and these were sequentially changed to "periodic structure 12" to "periodic structure 21". ”. Further, a simulation was also conducted for a configuration in which the width Wn was 0.65 mm, that is, a configuration in which a straight normal wiring 90 was provided (denoted as "normal wiring" in FIG. 12).
For "periodic structure 12" to "periodic structure 21", simulation results were obtained in which the absolute value of Δk was smaller than that of "normal wiring" and far-end crosstalk S ₄₁ could be reduced. Among these, in "periodic structure 12" to "periodic structure 16" (range R2 in FIG. 12) where Δk is 0 or more and 0.009 or less, far-end crosstalk S ₄₁ can be brought almost to zero.

FIG. 13 shows simulation results of far-end crosstalk when the width Ww is 0.6 mm and the interval G1 is 0.18 mm. The simulation was performed by changing the width Wn of the first portion 31 and the second portion 32 of the guard wiring 30 from 0.1 mm to 0.5 mm in 0.05 mm increments, and sequentially changing the widths Wn of the first portion 31 and the second portion 32 of the guard wiring 30 from “periodic structure 22” to “periodic structure 30”. ”. Further, a simulation was also conducted for a configuration in which the width Wn was 0.6 mm, that is, a configuration in which a straight normal wiring 90 was provided (denoted as "normal wiring" in FIG. 13).
For "periodic structure 22" to "periodic structure 30", simulation results were obtained in which the absolute value of Δk was smaller than that of "normal wiring" and far-end crosstalk S ₄₁ could be reduced.

FIG. 14 shows simulation results of far-end crosstalk when the width Ww is 0.55 mm and the interval G1 is 0.205 mm. The simulation was performed by changing the width Wn of the first portion 31 and the second portion 32 of the guard wiring 30 from 0.1 mm to 0.45 mm in 0.05 mm increments, and these were sequentially changed to "periodic structure 31" to "periodic structure 38". ”. Further, a simulation was also performed for a configuration in which the width Wn was 0.55 mm, that is, a configuration in which a straight normal wiring 90 was provided (denoted as "normal wiring" in FIG. 14).
For "periodic structure 31" to "periodic structure 38", simulation results were obtained in which the absolute value of Δk was smaller than that of "normal wiring" and far-end crosstalk S ₄₁ could be reduced.

FIG. 15 shows simulation results of far-end crosstalk when the width Ww is 0.5 mm and the interval G1 is 0.23 mm. The simulation was performed by changing the width Wn of the first portion 31 and the second portion 32 of the guard wiring 30 from 0.1 mm to 0.4 mm in 0.05 mm increments, and these were sequentially changed to "periodic structure 39" to "periodic structure 45". ”. Further, a simulation was also performed for a configuration in which the width Wn was 0.5 mm, that is, a configuration in which a straight normal wiring 90 was provided (denoted as "normal wiring" in FIG. 15).
For "periodic structure 39" to "periodic structure 45", simulation results were obtained in which the absolute value of Δk was smaller than that of "normal wiring" and far-end crosstalk S ₄₁ could be reduced.

FIG. 16 shows simulation results of far-end crosstalk when the width Ww is 0.45 mm and the interval G1 is 0.255 mm. The simulation was performed by changing the width Wn of the first portion 31 and the second portion 32 of the guard wiring 30 from 0.1 mm to 0.35 mm in 0.05 mm increments, and these were sequentially changed to "periodic structure 46" to "periodic structure 51". ”. Further, a simulation was also conducted for a configuration in which the width Wn was 0.45 mm, that is, a configuration in which a straight normal wiring 90 was provided (denoted as "normal wiring" in FIG. 16).
For "periodic structure 46" to "periodic structure 51", simulation results were obtained in which the absolute value of Δk was smaller than that of "normal wiring" and far-end crosstalk S ₄₁ could be reduced.

FIG. 17 is a diagram showing the effect of reducing far-end crosstalk S ₄₁ when each periodic structure is adopted in the simulations of FIGS. 11 to 16.
Each row of the table in FIG. 17 represents a width Ww=0.45 mm to 0.7 mm, and each column represents a width Wn=0.1 mm to 0.7 mm. In addition, each cell corresponding to the intersection of the row and column (excluding cells marked with "-") corresponds to one of the periodic structures 1 to 45 or one configuration employing normal wiring, The effect of reducing far-end crosstalk _S41 in this configuration is shown.
In FIG. 17, "○" indicates that far-end crosstalk S ₄₁ is suppressed to less than -20 dB in the frequency band of 0 (DC) to 50 GHz.
In addition, "□" indicates that far-end crosstalk S ₄₁ is suppressed to less than -20 dB in the frequency band from 0 to 45 GHz, and far-end crosstalk S ₄₁ is suppressed to -20 dB or more in a part of the frequency band from 45 GHz to 50 GHz. represents becoming.
In addition, "△" indicates that although the far-end crosstalk _S41 is -20 dB or more in a part of the frequency band from 0 to 45 GHz, it is better than the far-end crosstalk _S41 of "normal wiring". .
Further, "x" represents far-end crosstalk _S41 of "normal wiring".

In the range R1 shown in FIG. 17 (“periodic structure 7” to “periodic structure 9” where Δk is 0 or more and 0.009 or less), the effect of reducing far-end crosstalk S ₄₁ is particularly high. Ta. In the range R1, the interval G (0.96 mm) is approximately three times the wiring width W (0.32 mm), and the width Ww (0.7 mm) of the third portion 33 in the Y direction is approximately two times the wiring width W. .2 times the width Wn (0.4 mm to 0.5 mm) of the first portion 31 and the second portion 32 in the Y direction is larger than 1.2 times the wiring width W, and This corresponds to a range of less than 1.6 times.

Further, even in the range R2 (“periodic structure 12” to “periodic structure 16” where Δk is 0 or more and 0.009 or less) shown in FIG. 17, the effect of reducing far-end crosstalk S ₄₁ is particularly high. Obtained. In the range R2, the interval G (0.96 mm) is approximately three times the wiring width W (0.32 mm), and the width Ww (0.65 mm) of the third portion 33 in the Y direction is approximately two times the wiring width W. a range in which the width Wn (0.1 mm to 0.3 mm) of the first portion 31 and the second portion 32 in the Y direction is greater than 1/3 of the wiring width W and less than the wiring width W. corresponds to

In the present disclosure, when a numerical value is marked with "approximately", the range includes a range of 0.9 times or more and 1.1 times or less of the numerical value. For example, "the spacing G is approximately three times the wiring width W" indicates that "the spacing G is 2.7 times or more and 3.3 times or less the wiring width W."

FIG. 18 is a diagram showing, in comparison with Comparative Examples 1 and 2, the effect of reducing far-end crosstalk S ₄₁ when using the guard wiring 30 of "periodic structure 13" included in range R2. As shown in FIG. 12, the "periodic structure 13" is a periodic structure with a width Ww=0.65 mm and a width Wn=0.15 mm.
The horizontal axis in FIG. 18 represents the frequency of the transmission signal, and the vertical axis represents the magnitude of far-end crosstalk _S41 at each frequency. As shown in the dashed and broken line graphs in FIG. 18, in Comparative Examples 1 and 2, far-end crosstalk S ₄₁ worsens to -20 dB or more in a high frequency band of 15 GHz or more. On the other hand, as shown in the solid line graph in FIG. 18, when the guard wiring 30 with the "periodic structure 13" is used, the far-end crosstalk S ₄₁ is -20 dB over the entire range from DC (0 Hz) to 50 GHz. The result was obtained that the amount was reduced to less than

FIG. 19 shows the effective relative permittivity ε _re in the common mode and the effective relative permittivity ε _ro in the differential mode when using the guard wiring 30 of the "periodic structure 13" in Comparative Example 1, 3 is a diagram shown in comparison with Comparative Example 2. FIG. As can be seen from FIG. 19, by using the guard wiring 30 of the "periodic structure 13", the relative permittivity ε _re and ε _ro (as described above, mainly the relative permittivity ε _ro ) are adjusted, and Compared to Comparative Example 2, the difference between the relative permittivity ε _re and the relative permittivity ε _ro is effectively reduced. This effectively reduces far-end crosstalk _S41 .

Next, with reference to FIG. 20, the influence of the presence or absence of the resistance element 80 at both ends of the guard wiring 30 and the resistance value of the resistance element 80 on the far-end crosstalk _S41 will be described.

Each row in FIG. 20 shows a mode of electrical connection between the near-end terminal 34 of the guard wiring 30 shown in FIG. 1 and the pad electrode 60 (hereinafter referred to as "terminal resistor connection mode"). Specifically, "short circuit" means that the terminal 34 and the pad electrode 60 are directly electrically connected without using the resistive element 80, and the values from "10 Ω" to "300 Ω" indicate that the terminal 34 and the pad electrode 60 are directly electrically connected without using the resistive element 80. This indicates that a resistive element 80 having a resistance value of this value is mounted between the terminal 34 and the electrode 60, and "open" indicates that the terminal 34 and the pad electrode 60 are not electrically connected.
Furthermore, each column in FIG. 20 shows the connection mode of the terminating resistor at the far end side (between the terminal 35 and the pad electrode 60) of the guard wiring 30 shown in FIG. The contents represented by "short circuit", resistance values of "10 Ω" to "300 Ω", and "open" are the same as those on the near end side.
Further, in the simulation of FIG. 20, the guard wiring 30 of the "periodic structure 16" included in the range R2 was used, and only the connection mode of the terminating resistors on the near end side and the far end side was changed. As shown in FIG. 12, the "periodic structure 16" is a periodic structure with a width Ww=0.65 mm and a width Wn=0.3 mm. Further, the characteristic impedance Z _p of the guard wiring 30 of the “periodic structure 16” is 45Ω.

Each cell corresponding to the intersection of the row and column in FIG. 20 represents the effect of reducing far-end crosstalk S ₄₁ in a configuration in which the connection manner of each terminating resistor on the near-end side and the far-end side is combined.
Specifically, "◎" indicates that far-end crosstalk S ₄₁ is suppressed to less than -22 dB in the frequency band of 0 (DC) to 50 GHz. That is, "◎" indicates that an even higher effect of reducing far-end crosstalk _S41 than "○" in FIG. 17 can be obtained.
Further, "○", like "○" in FIG. 17, indicates that far-end crosstalk S ₄₁ is suppressed to less than -20 dB in the frequency band of 0 to 50 GHz.
Further, hatched blank spaces indicate that the far-end crosstalk S ₄₁ is −20 dB or more in a part of the frequency band from 0 to 50 GHz.

As can be seen from FIG. 20, even when the guard wiring 30 is not electrically connected to the GND layer 50 (when both the near end side and the far end side are "open"), "○ ”, and a sufficient far-end crosstalk _S41 reduction effect can be obtained.

Further, one end of the guard wiring 30 is electrically connected to the GND layer 50 without passing through the resistance element 80, and the other end has a resistance of 20Ω or more and 300Ω or less with respect to the GND layer 50. When electrically connected via the element 80 (one of the near end and far end is "short-circuited" and the other is one of "20 Ω" to "300 Ω"), " The result is ``○'' or ``◎'', and a sufficient effect of reducing far-end crosstalk _S41 can be obtained.

Further, when one end and the other end of the guard wiring 30 are electrically connected to the GND layer 50 via a resistance element 80 of 10Ω or more and 300Ω or less (near end side and far end side) If the resistance on each end side is any one of "10Ω" to "300Ω"), the result is "○" or "◎", and a sufficient effect of reducing far-end crosstalk S ₄₁ can be obtained.

Further, one end of the guard wiring 30 is not electrically connected to the GND layer 50, and the other end is electrically connected to the GND layer 50 through a resistance element 80 of 10Ω or more and 300Ω or less. (when one of the near end and far end is "open" and the other is between "10Ω" and "300Ω"), the result is "○" and the result is sufficient. The effect of reducing far-end crosstalk _S41 can be obtained.

Further, one end and the other end of the guard wiring 30 are electrically connected to the GND layer 50 via a resistive element 80 having a characteristic impedance Z _p (45Ω) or more and 100Ω or less of the guard wiring 30, respectively. If it is connected (if the near end and far end are either "45 Ω" to "100 Ω", which corresponds to the range r1 shown by the chain line in FIG. 20), the result will be "◎" and the value will be 0. Far-end crosstalk S ₄₁ can be reduced to less than -22 dB over the frequency band ~50 GHz.

Further, one end of the guard wiring 30 is electrically connected to the GND layer 50 without using the resistive element 80, and the other end is connected to the GND layer 50 with respect to the characteristics of the guard wiring 30. When electrically connected via a resistance element 80 with impedance Z _p or more and 200Ω or less (one of the near end and far end is “shorted” and the other is between “45Ω” and “200Ω”) (corresponding to the range r2 indicated by the broken line in Fig. 20), the result is "◎", and it is possible to reduce the far-end crosstalk _S41 to less than -22 dB over the frequency band of 0 to 50 GHz. can.

Further, when at least one end of the guard wiring 30 is electrically connected to the resistive element 80 via the resistive element 80 having a resistance value substantially the same as the characteristic impedance Z _p of the guard wiring 30, When at least one of the near end side and the far end side is "45 Ω" (corresponding to the range r3 shown by the solid line in Fig. 20), the result is "◎", and the far end Crosstalk S ₄₁ can be reduced to less than -22 dB. Note that the other end may be set to "10Ω" to "200Ω". Alternatively, it may be referred to as a "short circuit."

〔effect〕
As described above, the printed wiring board 1 according to the present embodiment includes the insulator 40, the first wiring 10 extending in the X direction on the first surface 41 of the insulator 40, and a second wiring 20 extending in the X direction parallel to the first wiring 10; and a second wiring 20 located between the first wiring 10 and the second wiring 20 on the first surface 41 of the insulator 40 and extending in the An extending guard wiring 30 is provided. The guard wiring 30 has a periodically meandering meander shape. By providing such a guard wiring 30, the first wiring 10 and the second wiring 20 are arranged so that the effective dielectric constant ε _re in the common mode approaches the effective dielectric constant ε _ro in the differential mode. It is possible to adjust the effective dielectric constant (mainly the dielectric constant ε _ro ) around . Thereby, far-end crosstalk _S41 can be effectively reduced.

Further, the guard wiring 30 has a first portion 31 whose distance to the first wiring 10 in the Y direction is shorter than the distance to the second wiring 20, and a distance from the second wiring 20 in the Y direction to the first wiring 31. The second portion 32 which is closer than the second portion 10 is connected to the second portion 32 periodically and alternately along the X direction, and connects the first portion 31 and the second portion 32 in the Y direction. The first portion 31, the second portion 32, and the third portion 33 have the same width in the X direction. According to such a configuration, the first portion 31, the third portion 33, the second portion 32, and the third portion 33 can be repeatedly arranged in this order with high density in the X direction. Thereby, the influence of the guard wiring 30 on the transmission of high frequency signals in the wiring L1 and the wiring L2 can be reduced.

Further, the first wiring 10 and the second wiring 20 have a predetermined wiring width W in the Y direction, and the distance G between the first wiring 10 and the second wiring 20 in the Y direction is approximately 3 of the wiring width W. The width Ww of the third portion 33 in the Y direction is approximately twice the wiring width W, and the width Wn of the first portion 31 and the width Wn of the second portion 32 in the Y direction are the wiring width It may be larger than 1/3 of W and less than the wiring width W. With such a configuration, Δk in equation (3) can be made particularly small (in the above embodiment, 0 or more and 0.009 or less). Therefore, far-end crosstalk _S41 can be reduced more effectively.

Further, the first wiring 10 and the second wiring 20 have a predetermined wiring width W in the Y direction, and the distance G between the first wiring 10 and the second wiring 20 in the Y direction is approximately 3 of the wiring width W. The width Ww of the third portion 33 in the Y direction is approximately 2.2 times the wiring width W, and the width of the first portion 31 and the width of the second portion 32 in the Y direction are the wiring width Ww. It may be larger than 1.2 times W and less than 1.6 times the wiring width W. With such a configuration, Δk in equation (3) can be made particularly small (in the above embodiment, 0 or more and 0.009 or less). Therefore, far-end crosstalk _S41 can be reduced more effectively.

Further, in a configuration in which the printed wiring board 1 includes a GND layer 50 set to a ground potential, the guard wiring 30 does not need to be electrically connected to the GND layer 50. Even with such a simple configuration, a sufficient effect of reducing far-end crosstalk _S41 can be obtained.

Further, in a configuration in which the printed wiring board 1 includes a GND layer 50 that is set to a ground potential, one end of the guard wiring 30 is electrically connected to the GND layer 50 without using the resistive element 80. Alternatively, the other end of the guard wiring 30 may be electrically connected to the GND layer 50 via a resistance element 80 of 20Ω or more and 300Ω or less. By connecting the near end and the far end of the guard wiring 30 in this manner, a sufficient effect of reducing far end crosstalk _S41 can be obtained.

In addition, in a configuration in which the printed wiring board 1 includes a GND layer 50 having a ground potential, one end and the other end of the guard wiring 30 have a resistance of 10Ω or more and 300Ω or less with respect to the GND layer 50, respectively. They may be electrically connected via the resistance element 80. By connecting the near end and the far end of the guard wiring 30 in this manner, a sufficient effect of reducing far end crosstalk _S41 can be obtained.

Further, in a configuration in which the printed wiring board 1 includes a GND layer 50 set to a ground potential, one end of the guard wiring 30 is not electrically connected to the GND layer 50, and the other end of the guard wiring 30 is not electrically connected to the GND layer 50. The end portion may be electrically connected to the GND layer 50 via a resistance element 80 of 10Ω or more and 300Ω or less. By connecting the near end and the far end of the guard wiring 30 in this manner, a sufficient effect of reducing far end crosstalk _S41 can be obtained.

In addition, in a configuration in which the printed wiring board 1 includes a GND layer 50 that is set to a ground potential, one end and the other end of the guard wiring 30 have a characteristic of the guard wiring 30 with respect to the GND layer 50. They may be electrically connected via a resistance element 80 having an impedance of Z _p or more and 100Ω or less. By connecting the near end and far end of the guard wiring 30 in this way, the far end crosstalk S ₄₁ can be reduced to an extremely small value (less than -22 dB in the above embodiment) in a high frequency band of 50 GHz or less. can be reduced.

Further, in a configuration in which the printed wiring board 1 includes a GND layer 50 that is set to a ground potential, one end of the guard wiring 30 is electrically connected to the GND layer 50 without using the resistive element 80. Alternatively, the other end of the guard wiring 30 may be electrically connected to the GND layer 50 via a resistive element 80 having a characteristic impedance Z _p of the guard wiring 30 or more and 200Ω or less. By connecting the near end and far end of the guard wiring 30 in this way, the far end crosstalk S ₄₁ can be reduced to an extremely small value (less than -22 dB in the above embodiment) in a high frequency band of 50 GHz or less. can be reduced.

Further, in a configuration in which the printed wiring board 1 is provided with a GND layer 50 set to a ground potential, at least one end of the guard wiring 30 has a characteristic impedance Z _p of the guard wiring 30 with respect to the GND layer 50. They may be electrically connected via a resistance element 80 having the same resistance value. By making the resistance value of the resistance element 80 at one end substantially the same as the characteristic impedance Z _p , multiple reflections can be reduced. In the following high frequency bands, far-end crosstalk S ₄₁ can be reduced to an extremely small value (less than -22 dB in the above embodiment). Note that the resistance value of the other end may be set to "10Ω" to "200Ω". Furthermore, the other end may be "short-circuited".

〔others〕
Note that the above embodiment is an example, and various changes are possible.
For example, the shape of the guard wiring 30 as the third wiring is not limited to that shown in FIG. , and a second portion whose distance to the second wiring 20 in the Y direction is shorter than the distance to the first wiring 10 are connected in an arbitrary shape (periodic may be any meandering shape). In this case, the first part and the second part may be directly connected and the third part may not be provided. Further, the distance between the first part and the first wiring 10 in the Y direction and the distance with the second wiring 20 may not be uniform, and the distance between the second part and the first wiring 10 in the Y direction may not be uniform. Also, the distance to the second wiring 20 may not be uniform. For example, the third wiring may have a sine curve shape, a triangular wave shape, or the like.

Further, in the above embodiment, the first wiring 10 and the second wiring 20 are linear, but the present invention is not limited to this. You may do so. In this case as well, the guard wiring 30 is bent in the same manner as the first wiring 10 and the second wiring 20, and the guard wiring 30 is provided between the first wiring 10 and the second wiring 20. The effect of reducing far-end crosstalk can be obtained.

In addition, specific details such as the configuration, structure, positional relationship, and shape shown in the above embodiments can be changed as appropriate without departing from the spirit of the present disclosure. Furthermore, the configurations, structures, positional relationships, and shapes shown in the above embodiments can be combined as appropriate without departing from the spirit of the present disclosure.

1 Printed wiring board 10 First wiring 11 Leading wiring 20 Second wiring 21 Leading wiring 30 Guard wiring (third wiring)
31 First part 32 Second part 33 Third part 34, 35 Terminal 40 Insulator 50 GND layer (ground conductor)
60 Pad electrode 70 Via 80 Resistance element 90 Normal wiring L1, L2 Wiring U Unit structure p1 to p4 Wiring end

Claims (11)

an insulator;
a first wiring extending in a first direction on a first surface of the insulator;
a second wiring extending in the first direction so as to be parallel to the first wiring on the first surface of the insulator;
a third wiring located between the first wiring and the second wiring on the first surface of the insulator and extending in the first direction;
Equipped with
The third wiring has a periodically meandering meander shape,
Printed wiring board. The third wiring includes a first portion in which the distance from the first wiring in a second direction perpendicular to the first direction is shorter than the distance to the second wiring, and the second portion in the second direction. A second portion whose distance to the wiring is shorter than the distance to the first wiring forms a shape in which the first portion and the It has a third part extending in the second direction and connecting with the second part,
The first portion, the second portion, and the third portion have equal widths in the first direction.
The printed wiring board according to claim 1. The first wiring and the second wiring have a predetermined wiring width in the second direction,
The distance between the first wiring and the second wiring in the second direction is approximately three times the wiring width,
The width of the third portion in the second direction is approximately twice the wiring width,
The width of the first portion and the width of the second portion in the second direction are greater than 1/3 of the wiring width and less than the wiring width,
The printed wiring board according to claim 2. The first wiring and the second wiring have a predetermined wiring width in the second direction,
The distance between the first wiring and the second wiring in the second direction is approximately three times the wiring width,
The width of the third portion in the second direction is approximately 2.2 times the wiring width,
The width of the first portion and the width of the second portion in the second direction are greater than 1.2 times the wiring width and less than 1.6 times the wiring width.
The printed wiring board according to claim 2. Equipped with a ground conductor that is at ground potential,
the third wiring is not electrically connected to the ground conductor;
The printed wiring board according to any one of claims 1 to 4. Equipped with a ground conductor that is at ground potential,
One end of the third wiring is electrically connected to the ground conductor without a resistance element, and the other end of the third wiring has a resistance of 20Ω to the ground conductor. electrically connected via a resistance element of 300 Ω or more and 300 Ω or less,
The printed wiring board according to any one of claims 1 to 4. Equipped with a ground conductor that is at ground potential,
One end and the other end of the third wiring are each electrically connected to the ground conductor via a resistance element of 10Ω or more and 300Ω or less,
The printed wiring board according to any one of claims 1 to 4. Equipped with a ground conductor that is at ground potential,
One end of the third wiring is not electrically connected to the ground conductor, and the other end of the third wiring is a resistance element with a resistance of 10Ω or more and 300Ω or less with respect to the ground conductor. electrically connected through the
The printed wiring board according to any one of claims 1 to 4. Equipped with a ground conductor that is at ground potential,
One end and the other end of the third wiring are each electrically connected to the ground conductor via a resistance element having a characteristic impedance of the third wiring or more and 100Ω or less,
The printed wiring board according to any one of claims 1 to 4. Equipped with a ground conductor that is at ground potential,
One end of the third wiring is electrically connected to the ground conductor without a resistance element, and the other end of the third wiring is connected to the ground conductor, electrically connected via a resistance element having a characteristic impedance of the third wiring or more and 200Ω or less;
The printed wiring board according to any one of claims 1 to 4. Equipped with a ground conductor that is at ground potential,
At least one end of the third wiring is electrically connected to the ground conductor via a resistance element having a resistance value substantially the same as a characteristic impedance of the third wiring.
The printed wiring board according to any one of claims 1 to 4.

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