Printed wiring board

Abstract

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

Description

[Technical Field]

[0001] This disclosure relates to printed circuit boards. [Background technology]

[0002] There is a technology that transmits 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, near-end crosstalk and far-end crosstalk occurring between two wires are reduced by increasing the distance between the two wires or by providing a ground potential guard wire between the two wires. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2008-71971 [Overview of the project] [Problems that the invention aims to solve]

[0004] In recent years, printed circuit boards equipped with microstrip wiring have come to be used for signal transmission in high-frequency bands of several tens of GHz. In such high-frequency bands, there is a problem that far-end crosstalk cannot be sufficiently reduced even when the conventional crosstalk reduction methods described above are applied. [Means for solving the problem]

[0005] A printed circuit board according to one aspect of the present disclosure comprises an insulator and a first surface of the insulator extending in a first direction The signal propagates A first wiring and a first wiring extending in the first direction parallel to the first wiring on the first surface of the insulator The signal propagatesThe insulator comprises a second wiring and a third wiring located between the first and second wirings on the first surface of the insulator and extending in the first direction. The third wiring has a meander shape that periodically meanders. [Effects of the Invention]

[0006] According to the information provided in this disclosure, far-end crosstalk can be effectively reduced. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram shows the configuration of a printed circuit board. [Figure 2] This is a diagram showing a cross-section along line AA in Figure 1. [Figure 3] This is a diagram showing the configuration of the guard wiring. [Figure 4] This diagram shows the configuration of a printed circuit board according to Comparative Example 1. [Figure 5] This figure shows the configuration of a printed circuit board according to Comparative Example 2. [Figure 6] This diagram shows the electric field lines generated in common mode. [Figure 7] This diagram shows the electric field lines generated in differential mode. [Figure 8] This figure shows examples of relative permittivity εre and εro according to the periodic structure of guard wiring. [Figure 9] This figure shows the parameters used in the simulation. [Figure 10] This figure shows the parameters and configuration used in the simulation. [Figure 11] This figure shows the simulation results of far-end crosstalk when the width Ww is 0.7 mm and the spacing G1 is 0.13 mm. [Figure 12] This figure shows the simulation results of far-end crosstalk when the width Ww is 0.65 mm and the spacing G1 is 0.155 mm. [Figure 13]This figure shows the simulation results of far-end crosstalk when the width Ww is 0.6 mm and the spacing G1 is 0.18 mm. [Figure 14] This figure shows the simulation results of far-end crosstalk when the width Ww is 0.55 mm and the spacing G1 is 0.205 mm. [Figure 15] This figure shows the simulation results of far-end crosstalk when the width Ww is 0.5 mm and the spacing G1 is 0.23 mm. [Figure 16] This figure shows the simulation results of far-end crosstalk when the width Ww is 0.45 mm and the spacing G1 is 0.255 mm. [Figure 17] Figures 11-16 show the effect of reducing far-end crosstalk when each periodic structure is adopted in the simulations. [Figure 18] This figure shows the effect of reducing far-end crosstalk when using guard wiring, in comparison with Comparative Examples 1 and 2. [Figure 19] This figure shows the relative permittivity εre and εro when using guard wiring, in comparison with Comparative Example 1 and Comparative Example 2. [Figure 20] This diagram illustrates the effect of the connection configuration of termination resistors at both ends of a guard wire on far-end crosstalk. [Modes for carrying out the invention]

[0008] The embodiments will be described below with reference to the drawings. However, for the sake of clarity, the drawings referenced below show only the main components necessary to explain the embodiments in a simplified manner. Therefore, the printed circuit board 1 of this disclosure may include any components not shown in the drawings referenced. Furthermore, the dimensions of the components in each drawing do not faithfully represent the dimensions and dimensional ratios of the actual components.

[0009] [Configuration of printed circuit board] The configuration of the printed circuit board 1 according to this embodiment will be described with reference to Figures 1 and 2. In the following, the orientation of each part of the printed circuit board 1 will be described using an XYZ Cartesian coordinate system in which the thickness direction of the printed circuit board 1 is the Z direction. The extension direction of the first wiring 10 and the second wiring 20, described later, provided on the printed circuit board 1 will be defined as the X direction, and the direction perpendicular to the X and Z directions will be defined as the Y direction. Figure 1 shows a part of the printed circuit board 1 viewed from the +Z direction in plan view. Figure 2 shows a part of the cross-section of the printed circuit board 1 in Figure 1, perpendicular to the Y direction at the position of line AA. In the following, the surface of each layer constituting the printed circuit board 1 facing the +Z direction will also be referred to as the "top surface," and the surface facing the -Z direction will also be referred to as the "bottom surface." The Z direction will also be referred to as the "thickness direction." Furthermore, viewing the printed circuit board 1 from the Z direction, with some of its components visible through it, will be referred to as "planar perspective."

[0010] As shown in Figures 1 and 2, the printed circuit board 1 comprises an insulator 40, wiring L1, wiring L2, guard wiring 30 (third wiring), and pad electrodes 60 provided on the first surface 41 (top surface) of the insulator 40, a GND layer 50 (ground conductor) provided on the second surface 42 (bottom surface) of the insulator 40 opposite to the first surface 41, and a resistive element 80 mounted on the first surface 41. Wiring L1, wiring L2, and the GND layer 50 constitute a microstrip type signal transmission path. Other wiring or circuit elements for signal transmission are connected to the wiring ends p1 and p2 of wiring L1, and the wiring ends p3 and p4 of wiring L2. The printed circuit board 1 may also have other insulators or conductor layers on the -Z direction side of the insulator 40 in Figure 2.

[0011] The insulator 40 is a flat plate-shaped member parallel to the XY plane. The material of the insulator 40 is not particularly limited as long as it has insulating properties. Examples of materials for the insulator 40 include epoxy resin, bismaleimide-triazine resin, polyphenylene ether (PPE) resin, polyimide resin, and liquid crystal polymer organic resins. These organic resins may also contain reinforcing materials such as glass cloth. The insulator 40 may also be formed by pressing and heating a prepreg (a member made by impregnating a reinforcing material such as glass cloth with resin and semi-curing it) to melt it and then curing it. The thickness of the insulator 40 may be, for example, several tens of micrometers to several hundred micrometers.

[0012] The wiring L1 has a linear first wiring 10 extending in the X direction (first direction) on the first surface 41 of the insulator 40, and routing wiring 11 extending from both ends of the first wiring 10. The wiring L2 has a linear second wiring 20 that extends in the X direction parallel to the first wiring 10 on the first surface 41 of the insulator 40, and routing wiring 21 extending from both ends of the second wiring 20. The second wiring 20 is parallel to the first wiring 10.

[0013] The guard wiring 30 is located between the first wiring 10 and the second wiring 20 on the first surface 41 of the insulator 40. The guard wiring 30 extends in the X direction while exhibiting a periodically meandering meander shape. The extent of the guard wiring 30 in the X direction is approximately equal to the extent of the first wiring 10 and the second wiring 20. However, it is not limited to this, and the guard wiring 30 may be longer or shorter than the first wiring 10 and the second wiring 20 in the X direction. The end of the guard wiring 30 on the -X direction side is terminal 34, and the end on the +X direction side is terminal 35.

[0014] The pad electrodes 60 are provided one each on the first surface 41 of the insulator 40, on the -X side of terminal 34 and on the +X side of terminal 35 of the guard wiring 30. A resistive element 80 can be mounted between terminal 34 and pad electrode 60, and between terminal 35 and pad electrode 60. Alternatively, the terminals 34 and pad electrode 60, and terminal 35 and pad electrode 60 may be electrically connected without the resistive element 80 (short-circuit configuration). Alternatively, the terminals 34 and pad electrode 60, and terminal 35 and pad electrode 60 may not be electrically connected (open configuration). Figure 1 illustrates a configuration in which a resistive element 80 is mounted between terminal 34 and pad electrode 60, and terminal 35 and pad electrode 60 are not electrically connected.

[0015] The materials of the wiring L1, wiring L2, guard wiring 30, and pad electrode 60 are not particularly limited as long as they are conductive. For example, the materials of the wiring L1, wiring L2, guard wiring 30, and pad electrode 60 may be copper. The copper may be formed by electroless plating or electrolytic plating, or it may be rolled copper foil. Alternatively, it may be a structure in which copper formed by plating is laminated onto rolled copper foil. The thickness of the wiring L1, wiring L2, guard wiring 30, and pad electrode 60 may be, for example, several μm to several tens of μm. The method of forming the wiring L1, wiring L2, guard wiring 30, and 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 be used. Furthermore, the wiring L1, wiring L2, the portion of the guard wiring 30 excluding the terminal 34, and the exposed surface of the first surface 41 of the insulator 40 may be covered with an insulating film (such as solder resist).

[0016] As shown in Figure 2, a GND layer 50, which is at ground potential, is provided on the second surface 42 of the insulator 40. The GND layer 50 is provided in an area that overlaps with wiring L1, wiring L2, and guard wiring 30 in a planar view. The GND layer 50 may be, for example, a solid block. The material of the GND layer 50 is not particularly limited as long as it is conductive, and may be, for example, copper.

[0017] As shown in Figure 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 consists of a conductor that fills the via hole that penetrates the insulator 40. The via 70 is formed, for example, by electroplating the insulator 40 with the via hole already drilled in it. The material of the via 70 may be, for example, copper. If the pad electrode 60 is electrically connected to terminal 34 or terminal 35 of the guard wiring 30, either via a resistive element 80 or directly without a resistive element 80, then terminal 34 or terminal 35 is electrically connected to the GND layer 50 via the pad electrode 60 and the via 70.

[0018] Next, with reference to Figure 3, the detailed configuration of the guard wiring 30 will be described. As described above, the guard wiring 30 exhibits a meandering meander shape. More specifically, the guard wiring 30 has a shape in which the first part 31 and the second part 32 are connected in an alternating manner in the X direction. Of these, the first part 31 is closer to the first wiring 10 in the Y direction (second direction) than to the second wiring 20. Similarly, the second part 32 is closer to the second wiring 20 in the Y direction than to the first wiring 10. The guard wiring 30 has a third part 33 that extends in the Y direction and connects the first part 31 and the second part 32. The position of the end of the third part 33 on the +Y direction side is flush with the position of the end of the first part 31 on the +Y direction side. The position of the end of the third part 33 on the -Y direction side is flush with the position of the end of the second part 32 on the -Y direction side.

[0019] In this embodiment, the first part 31, the second part 32, and the third part 33 are rectangles with sides parallel to either the X or Y direction. However, the corners of the rectangles and the corners of the connections between the first part 31 or the second part 32 and the third part 33 may be rounded. Also, the sides of the rectangles may be connected by sides that are inclined relative to each other (for example, sides that form a 45° angle). The side of the first part 31 on the -X side (side parallel to the Y direction) is connected to the side of the third part 33 located on the -X side of the first part 31 on the +X side (side parallel to the Y direction). The side of the first part 31 on the +X side (side parallel to the Y direction) is connected to the side of the third part 33 located on the +X side of the first part 31 on the -X side (side parallel to the Y direction). The -X-side edge (parallel to the Y-direction) of the second part 32 is connected to the +X-side edge of the third part 33, which is located on the -X-side of the second part 32. The +X-side edge (parallel to the Y-direction) of the second part 32 is connected to the -X-side edge of the third part 33, which is located on the +X-side of the second part 32. In Figure 3, the first part 31, the second part 32, and the third part 33 are depicted separately, but in reality, the first part 31, the second part 32, and the third part 33 are connected as a single unit.

[0020] The guard wiring 30 has a shape in which a unit structure U consisting of a pair of X-directionally adjacent third portions 33, a first portion 31, a third portion 33, and a second portion 32 is repeatedly arranged in the X direction. The length of the unit structure U in the X direction (the repetition period in the X direction) is defined as 2P hereinafter. Further, the total length of adjacent third portion 33 and first portion 31 in the X direction is P, and the total length of adjacent third portion 33 and second portion 32 in the X direction is also P. 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, when both the minimum wiring width and the minimum wiring spacing on the printed wiring board 1 are 0.1 mm, the lengths of the first portion 31, the second portion 32, and the third portion 33 in the X direction may all be set to 0.1 mm, and the length P may be set to 0.2 mm. Note that in the X direction, the lengths of the first portion 31 and the second portion 32 are not necessarily the same as the length of the third portion 33. The length of the third portion 33 may be set to aP, and the lengths of the first portion 31 and the second portion 32 may be set to (1-a)P, where a is a constant satisfying 0<a<1 / 2 or 1 / 2<a<1.

[0021] As shown in Figure 3, the width of the first wiring 10 and the second wiring 20 in the Y direction is the wiring width W. In other words, the wiring width W is the width of the short side of the first wiring 10 and the second wiring 20. The distance between the first wiring 10 and the second wiring 20 in the Y direction is the distance G. In other words, the distance G is the distance between the edge of the first wiring 10 on the side of the second wiring 20 and the edge of the second wiring 20 on the side of the first wiring 10 when the first wiring 10 and the second wiring 20 are arranged in parallel. 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 distance G1. In Figure 3, the distance G1 is shown in two places. The first distance G1 is the distance between the edge of the first wiring 10 on the side of the guard wiring 30 and the edge of the first portion 31 of the guard wiring 30 on the side of the first wiring 10. This is the portion showing the shortest distance between the first wiring 10 and the guard wiring 30. The second spacing G1 is the distance between the edge of the second wiring 20 on the side of the guard wiring 30 and the edge of the second portion 32 of the guard wiring 30 on the side of the second wiring 20. 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 exemplified as being between 1 / 5 and 1 / 2 of the spacing G when G is set to 1. Also, the width of the third portion 33 in the Y direction (the width of the guard wiring 30 in the Y direction) is width Ww. Width Ww is the length of the guard wiring 30 along the short side of the first wiring 10 and the second wiring 20. Here, "along the short side" means the length in the direction perpendicular to the longitudinal direction of the first wiring 10 and the second wiring 20. Width Ww is greater than the wiring width W of the first wiring 10 and the second wiring 20. Furthermore, the width of the first part 31 and the width of the second part 32 in the Y direction are equal to each other, and the width Wn is less than the width Ww.

[0022] As described above, by providing the guard wiring 30 having a periodic meander shape between the first wiring 10 and the second wiring 20, far-end crosstalk in the first wiring 10 and the second wiring 20 can be effectively reduced. Here, far-end crosstalk refers to the phenomenon that when the signal transmission directions of two parallel first wiring 10 and second wiring 20 are the same, a signal transmitted through one of the first wiring 10 and the second wiring 20 couples with a signal transmitted through the other. In the following, let S be the magnitude of far-end crosstalk when a signal input from the -X direction side (wiring end p1 side) of the first wiring 10 couples to a signal on the +X direction side (wiring end p4 side) of the second wiring 20 41 .

[0023] Far-end crosstalk S 41 is given by the following formula (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 formula (2). [Numerical formula] In addition, the following description may sometimes use Δk given by the following formula (3), where Δk is part of the numerator on the right-hand side of formula (2). [Numerical formula]

[0024] In formula (2), ε re is the effective relative dielectric constant around the first wiring 10 and the second wiring 20 in common mode, ε ro is the effective relative dielectric constant around the first wiring 10 and the second wiring 20 in differential mode, f is the frequency of the transmission signal, and c is the speed of light in vacuum. As can be seen from formulas (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 (the absolute value of Δk in formula (2)). Therefore, the effective relative dielectric constant ε in common mode reAnd the effective relative permittivity ε in differential mode ro By bringing them closer together (ideally by making them coincide), far-end crosstalk S 41 This can be reduced.

[0025] By providing guard wiring 30 having a periodic meander shape as in this embodiment, the far-end crosstalk S is reduced compared to the printed circuit board 1a in Comparative Example 1 shown in Figure 4 and the printed circuit board 1b in Comparative Example 2 shown in Figure 5. 41 This can be reduced. In this case, the printed circuit board 1a according to Comparative Example 1 shown in Figure 4 does not have guard wiring between the first wiring 10 and the second wiring 20 that extend in the X direction. Furthermore, the first wiring 10 and the second wiring 20 are arranged at intervals of three times the width of each wiring in the Y direction. The printed circuit board 1b in Comparative Example 2 shown in Figure 5 is the same as the printed circuit board 1a in Figure 4, but with a straight (non-serpentine) normal wiring 90 connected to the GND layer 50 between the first wiring 10 and the second wiring 20.

[0026] The common mode described above is one of two propagation modes when a signal propagates toward the far end (+X direction) in the first wiring 10 and the second wiring 20. In this mode, signals with the same phase flow through the first wiring 10 and the second wiring 20, and electric field lines are generated between the first wiring 10 and the GND layer 50. On the other hand, the differential mode is one of the two propagation modes described above. In this mode, signals with opposite phases flow through the first wiring 10 and the second wiring 20, and electric field lines are generated between the first wiring 10 and the second wiring 20, and between the first wiring 10 and the GND layer 50.

[0027] Figure 6 shows the electric field lines generated around the first wiring 10 and the second wiring 20 in common mode. Figure 7 shows the electric field lines generated around the first wiring 10 and the second wiring 20 in differential mode. Figures 6 and 7 show the electric field lines 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. Therefore, the relative permittivity on the GND layer 50 side (-Z direction side) of the first wiring 10 and the second wiring 20 (relative permittivity of the insulator 40: here, assumed to be 3.35) is different from the relative permittivity on the opposite side of the GND layer 50 (+Z direction side) (relative permittivity of air: 1). As shown in Figure 6, in common mode, electric field lines are mainly generated between the first wiring 10 and the second wiring 20 and the GND layer 50, so the effective relative permittivity ε re This value is relatively close to the relative permittivity of the insulator 40, which is 3.35. On the other hand, as shown in Figure 7, in differential mode, electric field lines are generated between the first wiring 10 and the second wiring 20, between the first wiring 10 and the GND layer 50, and between the second wiring 10 and the GND layer 50, and the proportion of electric field lines passing through the air is greater compared to common mode. Therefore, the effective relative permittivity ε in differential mode is ro ε is the effective relative permittivity in common mode. re It will become smaller than that. As a result, in microstrip wiring, the relative permittivity ε re and relative permittivity ε ro A difference arises between and , and according to this difference, the far-end crosstalk S shown in the above equations (1) and (2) 41 This occurs.

[0028] Furthermore, differences in the effective relative permittivity result in differences in signal propagation delay time. Therefore, the relative permittivity can be derived from the propagation delay time. Specifically, the propagation delay time of the common mode is t de , the propagation delay time of differential mode is t do Therefore, the relative permittivity ε is given by the following equations (4) and (5). re and relative permittivity ε ro This can be derived. ε re =(ct de / l) 2 …(4) ε ro =(ct do / l) 2 …(5)

[0029] By providing a meander-shaped guard wiring 30 between the first wiring 10 and the second wiring 20, the effective relative permittivity ε of the common mode re And the effective relative permittivity ε of the differential mode ro The distribution of electric field lines shown in Figures 6 and 7 can be changed so that the two approaches each other. This is because, in common mode, as shown in Figure 6, the electric field lines mainly pass through the interior of the insulator 40, so even if the distribution of electric field lines changes, the effective relative permittivity ε re While the relative permittivity ε does not change easily, in differential mode, as shown in Figure 7, the distribution of electric field lines changes because electric field lines pass through the air layer more, and the ratio of electric field lines passing through the air layer to the amount of electric field lines passing through the interior of the insulator 40 changes easily, and the effective relative permittivity ε ro This is because it is easily changed. In addition, the distribution of electric field lines can be further controlled by adjusting the widths Ww and Wn of the guard wiring 30. Relative permittivity ε re And the relative permittivity ε ro By adjusting the widths Ww and Wn so that they approach each other, the Δk shown in equation (3), i.e., the ΔK in equation (2), can be further reduced, and as a result, the far-end crosstalk S in equation (1) can be reduced. 41 This can be further reduced.

[0030] Figure 8 shows the relative permittivity ε corresponding to the periodic structure of the guard wiring 30. re , ε ro This is an example shown in the figure. In Figure 8, "Periodic Structure 21," "Periodic Structure 13," and "Periodic Structure 1" represent certain periodic structures of the guard wiring 30. Specifically, these three periodic structures have different combinations of widths Ww and Wn. The widths Ww and Wn in each of "Periodic Structure 21," "Periodic Structure 13," and "Periodic Structure 1" will be described later.

[0031] As shown in Figure 8, by changing the combination of widths Ww and Wn of the guard wiring 30, the effective relative permittivity ε in differential mode can be changed. ro (The dashed line graph in Figure 8) shows the effective relative permittivity ε in common mode.r It can be brought closer to (the solid line graph in Figure 8).

[0032] From the graph in Figure 8, in a periodic structure where an appropriate combination of widths Ww and Wn is selected, the effective relative permittivity ε in common mode is re And the effective relative permittivity ε in differential mode ro This can be reduced to 0. Therefore, by providing this appropriately periodic guard wiring 30, Δk shown in equation (3), that is, ΔK shown in equation (2), becomes 0, and the far-end crosstalk S shown in equation (1) becomes 0. 41 This eliminates far-end crosstalk S. 41 This can effectively reduce [the problem].

[0033] Referring to Figures 9 to 16, the simulation results of far-end crosstalk when the periodic structure (width Ww and width Wn) of the guard wiring 30 is changed will be explained. Figures 9 and 10 show the assumptions 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 spacing G between the first wiring 10 and the second wiring 20 was set to 0.96 mm. Therefore, the spacing G is three times the wiring width W. Also, the spacing G1 was set to a value that satisfies G1 = (G - Ww) / 2. Furthermore, it was assumed that the first surface 41 side of the insulator 40 was covered with solder resist, and the relative permittivity, dielectric loss tangent, and thickness of the solder resist and insulator 40 were as shown in Figures 9 and 10. Furthermore, the material of the first wiring 10, the second wiring 20, the guard wiring 30, and the GND layer 50 was set to copper, and the thickness was as shown in Figures 9 and 10. Furthermore, the resistance value of the resistive element 80 at both ends of the guard wiring 30 (between terminal 34 and pad electrode 60, and between terminal 35 and pad electrode 60) was set to the characteristic impedance Z of the guard wiring 30. p It was set to the same value as [the other value].

[0034] Figure 11 shows the simulation results of far-end crosstalk when the width Ww is 0.7 mm and the spacing G1 is 0.13 mm. The simulation was performed by changing the width Wn of the first part 31 and the second part 32 of the guard wiring 30 from 0.1 mm to 0.6 mm in 0.05 mm increments, and these were designated as "Periodic Structure 1" to "Periodic Structure 11" in order. Simulation was also performed for a configuration with a width Wn of 0.7 mm, that is, a configuration with a linear normal wiring 90 without a periodic structure, as in Comparative Example 2 in Figure 5 (labeled "Normal Wiring" in Figure 11). Figure 11 shows the characteristic impedance Z of the guard wiring 30 for each level of width Wn. p (Ω), characteristic impedance Z0 (Ω) of the first wiring 10 and the second wiring 20, effective relative permittivity ε in common mode re , the effective relative permittivity ε in differential mode ro , and Δk (far-end crosstalk S) in equation (3) 41 A quantity proportional to this is shown.

[0035] As shown in Figure 11, for "Periodic Structure 1" to "Periodic Structure 11", the absolute value of Δk is smaller than that of "Normal Wiring", and far-end crosstalk S 41 Simulation results were obtained that showed a reduction in far-end crosstalk S. Of these, in "Periodic Structure 7" to "Periodic Structure 9" (range R1 in Figure 11) where Δk is greater than or equal to 0 and less than or equal to 0.009, far-end crosstalk S 41 This can be reduced to almost zero. Note that when Δk is a negative value, far-end crosstalk S occurs on the high-frequency side. 41 Although the reduction effect is difficult to obtain, far-end crosstalk S 41 This can effectively reduce [the problem].

[0036] Figure 12 shows the simulation results of far-end crosstalk when the width Ww is 0.65 mm and the spacing G1 is 0.155 mm. The simulation was performed by changing the width Wn of the first part 31 and the second part 32 of the guard wiring 30 from 0.1 mm to 0.55 mm in 0.05 mm increments, and these were designated as "periodic structure 12" to "periodic structure 21" in order. A configuration with a width Wn of 0.65 mm, i.e., a configuration with a straight normal wiring 90, was also simulated (labeled "normal wiring" in Figure 12). For "Periodic Structure 12" to "Periodic Structure 21," the absolute value of Δk is smaller than that of "Normal Wiring," and far-end crosstalk S 41 Simulation results were obtained that could reduce the far-end crosstalk S. 41 It can be brought almost to zero.

[0037] Figure 13 shows the simulation results of far-end crosstalk when the width Ww is 0.6 mm and the spacing G1 is 0.18 mm. The simulation was performed by changing the width Wn of the first part 31 and the second part 32 of the guard wiring 30 from 0.1 mm to 0.5 mm in 0.05 mm increments, and these were designated as "periodic structure 22" to "periodic structure 30" in order. A configuration with a width Wn of 0.6 mm, i.e., a configuration with a straight normal wiring 90, was also simulated (labeled "normal wiring" in Figure 13). For "Periodic Structure 22" to "Periodic Structure 30," the absolute value of Δk is smaller than that of "Normal Wiring," and far-end crosstalk S 41 Simulation results showed that reduction was possible.

[0038] Figure 14 shows the simulation results of far-end crosstalk when the width Ww is 0.55 mm and the spacing G1 is 0.205 mm. The simulation was performed by changing the width Wn of the first part 31 and the second part 32 of the guard wiring 30 from 0.1 mm to 0.45 mm in 0.05 mm increments, and these were designated as "periodic structure 31" to "periodic structure 38" in order. A configuration with a width Wn of 0.55 mm, i.e., a configuration with a straight normal wiring 90, was also simulated (labeled "normal wiring" in Figure 14). For "Periodic Structure 31" to "Periodic Structure 38," the absolute value of Δk is smaller than that of "Normal Wiring," and far-end crosstalk S 41 Simulation results showed that reduction was possible.

[0039] Figure 15 shows the simulation results of far-end crosstalk when the width Ww is 0.5 mm and the spacing G1 is 0.23 mm. The simulation was performed by changing the width Wn of the first part 31 and the second part 32 of the guard wiring 30 from 0.1 mm to 0.4 mm in 0.05 mm increments, and these were designated as "periodic structure 39" to "periodic structure 45" in order. A configuration with a width Wn of 0.5 mm, i.e., a configuration with a straight normal wiring 90, was also simulated (labeled "normal wiring" in Figure 15). For "Periodic Structure 39" to "Periodic Structure 45," the absolute value of Δk is smaller than that of "Normal Wiring," and far-end crosstalk S 41 Simulation results showed that reduction was possible.

[0040] Figure 16 shows the simulation results of far-end crosstalk when the width Ww is 0.45 mm and the spacing G1 is 0.255 mm. The simulation was performed by changing the width Wn of the first part 31 and the second part 32 of the guard wiring 30 from 0.1 mm to 0.35 mm in 0.05 mm increments, and these were designated as "periodic structure 46" to "periodic structure 51" in order. A configuration with a width Wn of 0.45 mm, i.e., a configuration with a straight normal wiring 90, was also simulated (labeled "normal wiring" in Figure 16). For "Periodic Structure 46" to "Periodic Structure 51," the absolute value of Δk is smaller than that of "Normal Wiring," and far-end crosstalk S 41 Simulation results showed that reduction was possible.

[0041] Figure 17 shows the far-end crosstalk S when each periodic structure is adopted in the simulations in Figures 11-16. 41 This figure shows the reduction effect. In the table in Figure 17, each row represents a width Ww of 0.45 mm to 0.7 mm, and each column represents a width Wn of 0.1 mm to 0.7 mm. Furthermore, each cell corresponding to the intersection of a row and column (excluding cells marked "-") corresponds to one of the periodic structures 1 to 45, or a configuration employing normal wiring, and the far-end crosstalk S in that configuration. 41 This represents the reduction effect. In Figure 17, the circle (○) indicates the far-end crosstalk S in the frequency band from 0 (DC) to 50 GHz. 41 This indicates that the noise level is kept below -20dB. Furthermore, "□" indicates far-end crosstalk S in the 0-45GHz frequency band. 41 This is suppressed to less than -20dB, and far-end crosstalk S is reduced in some parts of the 45GHz-50GHz frequency band. 41 This indicates that the level is -20dB or higher. Additionally, "△" indicates far-end crosstalk S in a portion of the 0-45GHz frequency band. 41 Although the value is -20dB or more, the far-end crosstalk S of "normal wiring" 41 It indicates an improvement over the previous state. Also, "×" indicates far-end crosstalk S in "normal wiring". 41 It represents.

[0042] In the range R1 shown in Figure 17 (periodic structure 7 to periodic structure 9 where Δk is 0 or greater and 0.009 or less), far-end crosstalk S 41The results showed a particularly high reduction effect. Range R1 corresponds to a range where the spacing G (0.96 mm) is approximately 3 times the wiring width W (0.32 mm), the width Ww (0.7 mm) of the third part 33 in the Y direction is approximately 2.2 times the wiring width W, and the widths Wn (0.4 mm to 0.5 mm) of the first part 31 and the second part 32 in the Y direction are greater than 1.2 times the wiring width W and less than 1.6 times the wiring width W.

[0043] Furthermore, in the range R2 shown in Figure 17 (periodic structure 12 to periodic structure 16 where Δk is 0 or greater and 0.009 or less), far-end crosstalk S 41 The results showed a particularly high reduction effect. Range R2 corresponds to a range where the spacing G (0.96 mm) is approximately 3 times the wiring width W (0.32 mm), the width Ww (0.65 mm) of the third part 33 in the Y direction is approximately 2 times the wiring width W, and the widths Wn (0.1 mm to 0.3 mm) of the first part 31 and the second part 32 in the Y direction are greater than 1 / 3 of the wiring width W and less than the wiring width W.

[0044] In this disclosure, when a numerical value is preceded by "approximately," it includes a range of 0.9 times or more and 1.1 times or less of that value. For example, "the spacing G is approximately 3 times the wiring width W" means "the spacing G is 2.7 times or more and 3.3 times or less the wiring width W."

[0045] Figure 18 shows the far-end crosstalk S when using guard wiring 30 of the "periodic structure 13" included in range R2. 41 This figure shows the reduction effect in comparison with Comparative Examples 1 and 2. "Periodic structure 13" is a periodic structure with a width Ww = 0.65 mm and a width Wn = 0.15 mm, as shown in Figure 12. In Figure 18, the horizontal axis represents the frequency of the transmitted signal, and the vertical axis represents the far-end crosstalk S at each frequency. 41 This represents the magnitude of the far-end crosstalk S in the high-frequency band above 15 GHz. As shown in the dashed and broken lines in Figure 18, in Comparative Example 1 and Comparative Example 2, the far-end crosstalk S 41This deteriorates to -20dB or more. On the other hand, as shown in the solid line graph of Figure 18, when using the guard wiring 30 of the "periodic structure 13", far-end crosstalk S is observed over the entire range from DC (0Hz) to 50GHz. 41 The result showed a reduction to less than -20dB.

[0046] Figure 19 shows the effective relative permittivity ε in common mode when using the guard wiring 30 of the "periodic structure 13". re And the effective relative permittivity ε in differential mode ro This figure shows the difference between this and Comparative Example 1 and Comparative Example 2. As can be seen from Figure 19, by using the guard wiring 30 of the "periodic structure 13", the relative permittivity ε re , ε ro (As mentioned above, mainly the relative permittivity ε) ro The relative permittivity ε was adjusted and compared to Comparative Example 1 and Comparative Example 2. re and relative permittivity ε ro The difference is effectively reduced. As a result, far-end crosstalk S 41 This effectively reduces the problem.

[0047] Next, referring to Figure 20, the presence or absence of resistors 80 at both ends of the guard wiring 30, and the magnitude of the resistance value of the resistors 80, are related to the far-end crosstalk S 41 This explains the impact on the system.

[0048] Each row in Figure 20 shows the electrical connection configuration between the terminal 34 on the near end of the guard wiring 30 shown in Figure 1 and the pad electrode 60 (hereinafter referred to as the "connection configuration of the termination resistor"). Specifically, "short circuit" indicates that the terminal 34 and the pad electrode 60 are directly electrically connected without the resistive element 80; the values ​​from "10Ω" to "300Ω" indicate that a resistive element 80 with the corresponding resistance value is mounted between the terminal 34 and the pad electrode 60; and "open circuit" indicates that the terminal 34 and the pad electrode 60 are not electrically connected. Furthermore, each column in Figure 20 shows the connection configuration of the termination resistor on the far end side (between terminal 35 and pad electrode 60) of the guard wiring 30 shown in Figure 1. The meanings of "short circuit," resistance values ​​from "10Ω" to "300Ω," and "open circuit" are the same as those for the near end side. Furthermore, in the simulation shown in Figure 20, the guard wiring 30 of the "periodic structure 16" included in range R2 was used, and only the connection configuration of the termination resistors on the near and far ends was changed. The "periodic structure 16" is a periodic structure with a width Ww = 0.65 mm and a width Wn = 0.3 mm, as shown in Figure 12. Also, the characteristic impedance Z of the guard wiring 30 of the "periodic structure 16" is shown. p It is 45Ω.

[0049] Each cell corresponding to the intersection of rows and columns in Figure 20 represents the far-end crosstalk S in a configuration that combines the connection configurations of each termination resistor on the near-end and far-end sides. 41 This represents the reduction effect. For more details, "◎" indicates far-end crosstalk S in the frequency band of 0 (DC) to 50 GHz. 41 This indicates that the far-end crosstalk S is suppressed to less than -22 dB. In other words, "◎" indicates an even higher far-end crosstalk S than "○" in Figure 17. 41 This indicates that a reduction effect can be obtained. Furthermore, "○" is similar to "○" in Figure 17, and in the frequency band of 0-50 GHz, far-end crosstalk S 41 This indicates that the noise level is kept below -20dB. Additionally, the hatched blank spaces indicate far-end crosstalk S in a portion of the 0-50 GHz frequency band. 41 This indicates that the level is -20dB or higher.

[0050] As can be seen from Figure 20, even when the guard wiring 30 is not electrically connected to the GND layer 50 (when both the near end and far end are "open"), the result is "○", indicating sufficient far-end crosstalk S 41 This provides a reduction effect.

[0051] Further, when one end of the guard wiring 30 is electrically connected to the GND layer 50 without interposing the resistance element 80, and the other end is electrically connected to the GND layer 50 via the resistance element 80 having a resistance of 20Ω or more and 300Ω or less (when one of the near-end side and the far-end side is "short-circuited" and the other is any one of "20Ω" to "300Ω"), the result is "○" or "◎", and sufficient far-end crosstalk S 41 can obtain a reduction effect.

[0052] Further, when one end and the other end of the guard wiring 30 are each electrically connected to the GND layer 50 via the resistance element 80 having a resistance of 10Ω or more and 300Ω or less (when the near-end side and the far-end side are each any one of "10Ω" to "300Ω"), the result is "○" or "◎", and sufficient far-end crosstalk S 41 can obtain a reduction effect.

[0053] Further, when 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 via the resistance element 80 having a resistance of 10Ω or more and 300Ω or less (when one of the near-end side and the far-end side is "open" and the other is any one of "10Ω" to "300Ω"), the result is "○", and sufficient far-end crosstalk S 41 can obtain a reduction effect.

[0054] Furthermore, when one end and the other end of the guard wiring 30 are each electrically connected to the GND layer 50 via the resistance element 80 having a resistance equal to or higher than the characteristic impedance Z p (45Ω) of the guard wiring 30 and equal to or lower than 100Ω (when the near-end side and the far-end side are each any one of "45Ω" to "100Ω": corresponding to the range r1 indicated by the dashed line in FIG. 20), the result is "◎", and the far-end crosstalk S 41 can be reduced to less than -22dB over the frequency band from 0 to 50 GHz.

[0055] Further, one end of the guard wiring 30 is electrically connected to the GND layer 50 without the resistive element 80 interposed therebetween, and the other end is connected to the GND layer 50 with a characteristic impedance Z of the guard wiring 30 p When the guard wiring is electrically connected via a resistive element 80 having a resistance value equal to or greater than Z and equal to or less than 200Ω (when one of the near-end side and the far-end side is "short-circuited" and the other is any one of "45Ω" to "200Ω", which corresponds to the range r2 indicated by a broken line in FIG. 20), the result is also "◎", and far-end crosstalk S over the frequency band of 0 to 50 GHz 41 can be reduced to less than -22 dB.

[0056] Further, when at least one end of the guard wiring 30 is electrically connected to a resistive element 80 having a resistance value substantially equal to the characteristic impedance Z p of the guard wiring 30 via said resistive element 80 (when at least one of the near-end side and the far-end side is "45Ω", which corresponds to the range r3 indicated by a solid line in FIG. 20), the result is also "◎", and far-end crosstalk S over the frequency band of 0 to 50 GHz 41 can be reduced to less than -22 dB. Note that the other end may be set to "10Ω" to "200Ω", or may be "short-circuited".

[0057] [Effect] As described above, the printed wiring board 1 according to the present embodiment includes an insulator 40, a first wiring 10 extending in the X direction on a first surface 41 of the insulator 40, a 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 guard wiring 30 positioned between the first wiring 10 and the second wiring 20 on the first surface 41 of the insulator 40 and extending in the X direction. The guard wiring 30 is formed in a periodically meandering meander shape. By providing such a guard wiring 30, the effective relative permittivity ε in the common mode re and the effective relative permittivity ε in the differential mode ro are brought close to each other, so that the effective relative permittivity around the first wiring 10 and the second wiring 20 (mainly the relative permittivity ε ro ) can be adjusted. Thereby, the far-end crosstalk S41 This can effectively reduce [the problem].

[0058] Furthermore, the guard wiring 30 has a shape in which a first portion 31, whose distance in the Y direction to the first wiring 10 is shorter than its distance to the second wiring 20, and a second portion 32, whose distance in the Y direction to the second wiring 20 is shorter than its distance to the first wiring 10, are connected in a periodically alternating manner along the X direction, and has a third portion 33 extending in the Y direction that connects the first portion 31 and the second portion 32, and the widths of the first portion 31, second portion 32 and third portion 33 are equal to each other in the X direction. With this configuration, the first portion 31, third portion 33, second portion 32 and third portion 33 can be arranged repeatedly at high density in this order along the X direction. This reduces the influence of the guard wiring 30 on the transmission of high-frequency signals in wiring L1 and wiring L2.

[0059] Furthermore, the first wiring 10 and the second wiring 20 have a predetermined wiring width W in the Y direction, the distance G between the first wiring 10 and the second wiring 20 in the Y direction is approximately 3 times the wiring width W, the width Ww of the third portion 33 in the Y direction is approximately 2 times the wiring width W, and the widths Wn of the first portion 31 and the second portion 32 in the Y direction may be greater than 1 / 3 of the wiring width W and less than the wiring width W. With this configuration, Δk in equation (3) can be made particularly small (in the above embodiment, 0 or more and 0.009 or less). Thus, far-end crosstalk S can be more effectively reduced. 41 This can be reduced.

[0060] Furthermore, the first wiring 10 and the second wiring 20 have a predetermined wiring width W in the Y direction, the distance G between the first wiring 10 and the second wiring 20 in the Y direction is approximately 3 times 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 widths of the first portion 31 and the second portion 32 in the Y direction may be greater than 1.2 times the wiring width W and less than 1.6 times the wiring width W. With this configuration, Δk in equation (3) can be made particularly small (in the above embodiment, 0 or more and 0.009 or less). Thus, far-end crosstalk S can be more effectively reduced. 41 This can be reduced.

[0061] Furthermore, in a configuration in which the printed circuit board 1 has a GND layer 50 which is set to ground potential, the guard wiring 30 does not need to be electrically connected to the GND layer 50. Even with such a simple configuration, sufficient far-end crosstalk S 41 This provides a reduction effect.

[0062] Furthermore, in a configuration in which the printed circuit board 1 has a GND layer 50 which is at ground potential, one end of the guard wiring 30 may be electrically connected to the GND layer 50 without a resistive element 80, and the other end of the guard wiring 30 may be electrically connected to the GND layer 50 via a resistive element 80 with a resistance of 20Ω or more and 300Ω or less. Even by connecting the near end and far end of the guard wiring 30 in this manner, sufficient far-end crosstalk S can be avoided. 41 This provides a reduction effect.

[0063] Furthermore, in a configuration in which the printed circuit board 1 has a GND layer 50 that is at ground potential, one end and the other end of the guard wiring 30 may be electrically connected to the GND layer 50 via a resistive element 80 with a resistance of 10Ω or more and 300Ω or less. Even by connecting the near end and far end of the guard wiring 30 in this manner, sufficient far-end crosstalk S can be avoided. 41 This provides a reduction effect.

[0064] Furthermore, in a configuration where the printed circuit board 1 has a GND layer 50 which is at ground potential, one end of the guard wiring 30 may not be electrically connected to the GND layer 50, and the other end of the guard wiring 30 may be electrically connected to the GND layer 50 via a resistive element 80 with a resistance of 10Ω or more and 300Ω or less. Even by configuring the connection of the near and far ends of the guard wiring 30 in this way, sufficient far-end crosstalk S can be avoided. 41 This provides a reduction effect.

[0065] Furthermore, in a configuration where the printed circuit board 1 has a GND layer 50 which is set to ground potential, one end and the other end of the guard wiring 30 are each at the characteristic impedance Z of the guard wiring 30 relative to the GND layer 50. p They may also be electrically connected via a resistive element 80 with a resistance of 100Ω or less. By connecting the near end and far end of the guard wiring 30 in this manner, far-end crosstalk S can be reduced in the high-frequency band of 50GHz or less. 41 This can be reduced to an extremely small value (less than -22 dB in the above embodiment).

[0066] Furthermore, in a configuration in which the printed circuit board 1 has a GND layer 50 which is at ground potential, one end of the guard wiring 30 is electrically connected to the GND layer 50 without a resistive element 80, and the other end of the guard wiring 30 is connected to the GND layer 50 with respect to the characteristic impedance Z of the guard wiring 30. p They may also be electrically connected via a resistive element 80 with a resistance of 200Ω or less. By connecting the near end and far end of the guard wiring 30 in this manner, far-end crosstalk S can be reduced in the high-frequency band of 50GHz or less. 41 This can be reduced to an extremely small value (less than -22 dB in the above embodiment).

[0067] Furthermore, in a configuration in which the printed circuit board 1 has a GND layer 50 which is set to ground potential, at least one end of the guard wiring 30 is at the characteristic impedance Z of the guard wiring 30 relative to the GND layer 50. pIt may also be electrically connected via a resistive element 80 with approximately the same resistance value. The resistance value of the resistive element 80 at one end is the characteristic impedance Z p By making it nearly identical, multiple reflections can be reduced, and therefore, regardless of the resistance value of the resistive element 80 connected to the other end, far-end crosstalk S in the high-frequency band of 50 GHz or less can be reduced. 41 This can be reduced to an extremely small value (less than -22 dB in the above embodiment). The resistance value of the other end may be "10 Ω" to "200 Ω". Furthermore, the other end may be "short-circuited".

[0068] 〔others〕 The above embodiment is illustrative and can be modified in various ways. For example, the shape of the guard wiring 30 as the third wiring is not limited to that shown in Figure 3, and may be any shape (a periodic meander shape) in which a first part is closer to the first wiring 10 in the Y direction than the second wiring 20, and a second part is closer to the second wiring 20 in the Y direction than the first wiring 10, are connected in an alternating manner along the X direction. In this case, the first and second parts may be directly connected, and there may be no third part. Furthermore, the distances of the first part to the first wiring 10 and the second wiring 20 in the Y direction do not have to be uniform, and the distances of the second part to the first wiring 10 and the second wiring 20 in the Y direction do not have to be uniform. For example, the third wiring may be a sine wave shape or a triangular wave shape.

[0069] Furthermore, although the above embodiment was described using an example in which the first wiring 10 and the second wiring 20 are straight, the invention is not limited to this, and the first wiring 10 and the second wiring 20 may be bent while running parallel to each other. In this case as well, by bending the guard wiring 30 in the same way as the first wiring 10 and the second wiring 20, and providing the guard wiring 30 between the first wiring 10 and the second wiring 20, the same far-end crosstalk reduction effect as in the above embodiment can be obtained.

[0070] Furthermore, specific details such as the configuration, structure, positional relationships, and shapes shown in the above embodiments can be modified as appropriate without departing from the spirit of this disclosure. In addition, the configuration, structure, positional relationships, and shapes shown in the above embodiments can be combined as appropriate without departing from the spirit of this disclosure. [Explanation of symbols]

[0071] 1 Printed wiring board 10 1st wiring 11. Wiring 20 2nd wiring 21. Wiring 30 Guard wiring (third wiring) 31 Part 1 32 Part 2 33 Part 3 Terminals 34 and 35 40 Insulator 50 GND layer (ground conductor) 60 pad electrodes 70 Beer 80 Resistor elements 90 Normal wiring L1, L2 wiring U Unit Structure p1~p4 Wiring end

Claims

1. Insulator and, A first wiring extending in a first direction on the first surface of the insulator, through which a signal propagates, A second wiring extends in the first direction parallel to the first wiring on the first surface of the insulator, and through which a signal propagates, A 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, Equipped with, The third wiring has a meander shape that periodically meanders. Printed wiring board.

2. The third wiring has a shape in which a first portion is connected to the first wiring in a second direction perpendicular to the first direction at a distance from the first wiring that is shorter than the distance from the second wiring, and a second portion is connected to the second wiring in a second direction at a distance shorter than the distance from the first wiring that is shorter than the distance from the first wiring, so as to be arranged alternately and periodically along the first direction, and has a third portion extending in the second direction that connects the first portion and the second portion. The first part, the second part, and the third part have equal widths in the first direction. The printed circuit board according to claim 1.

3. The first and second wirings have a predetermined wiring width in the second direction. The distance between the first and second wiring in the second direction is 2.7 times or more and 3.3 times or less the wiring width. The width of the third portion in the second direction is 1.8 times or more and 2.2 times or less the wiring width. The width of the first portion and the width of the second portion in the second direction are greater than one-third of the wiring width and less than the wiring width. The printed circuit board according to claim 2.

4. The first and second wirings have a predetermined wiring width in the second direction. The distance between the first and second wiring in the second direction is 2.7 times or more and 3.3 times or less the wiring width. The width of the third portion in the second direction is 1.98 times or more and 2.42 times or less 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 circuit board according to claim 2.

5. Equipped with a grounding conductor that is considered to be at ground potential, The third wiring is not electrically connected to the ground conductor. A printed circuit board according to any one of claims 1 to 4.

6. Equipped with a grounding conductor that is considered to be at ground potential, One end of the third wiring is electrically connected to the ground conductor without a resistive element, and the other end of the third wiring is electrically connected to the ground conductor via a resistive element with a resistance of 20 Ω or more and 300 Ω or less. A printed circuit board according to any one of claims 1 to 4.

7. Equipped with a grounding conductor that is considered to be at ground potential, One end and the other end of the third wiring are electrically connected to the ground conductor via a resistive element with a resistance of 10 Ω or more and 300 Ω or less. A printed circuit board according to any one of claims 1 to 4.

8. Equipped with a grounding conductor that is considered to be 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 electrically connected to the ground conductor via a resistive element with a resistance of 10 Ω or more and 300 Ω or less. A printed circuit board according to any one of claims 1 to 4.

9. Equipped with a grounding conductor that is considered to be at ground potential, One end and the other end of the third wiring are electrically connected to the ground conductor via a resistive element with a resistance impedance equal to or greater than the characteristic impedance of the third wiring and less than or equal to 100 Ω. A printed circuit board according to any one of claims 1 to 4.

10. Equipped with a grounding conductor that is considered to be at ground potential, One end of the third wiring is electrically connected to the ground conductor without a resistive element, and the other end of the third wiring is electrically connected to the ground conductor via a resistive element having a resistance impedance greater than or equal to the characteristic impedance of the third wiring and less than or equal to 200 Ω. A printed circuit board according to any one of claims 1 to 4.

11. Equipped with a grounding conductor that is considered to be at ground potential, At least one end of the third wiring is electrically connected to the ground conductor via a resistive element with a resistance value approximately the same as the characteristic impedance of the third wiring. A printed circuit board according to any one of claims 1 to 4.

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