JP2009100170A - Differential wires, wiring board, wiring structure, and differential transmission line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide low-crosstalk high-speed high-density differential wires, capable of reducing the near-end and far-end crosstalks of the differential wires that mutually adjoin in unlimited manner, substantially making it 0 in the permissible error range. <P>SOLUTION: In a stacked pair of differential wires having differential wires using, as a pair, wires 1 wherein the thickness of the wire is smaller than the width of the wire, and reference grounds 3 for the wires, ground wires 2 are arranged, at positions close to the reference grounds 3 between the adjacent differential wires. Preferably, the ground wires 2 are arranged vertically symmetric, adjacent to the upper and lower reference grounds 3 between the adjacent differential wires. The thickness of the wire 1 is set to enable canceling the near-end crosstalks of the differential wires. The distance between the ground wire 2 and the reference ground 3 is set so as to be able to cancel the far-end crosstalks of the differential wires. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to differential wiring, a wiring board and wiring structure having the differential wiring, and a differential transmission path, and more particularly to the configuration of the differential wiring.

  With the increase in circuit speed and density, there is a need to reduce crosstalk even in differential lines (differential wiring). A differential line is a signal in which two lines (wirings) are paired, and are inverted from each other on the plus side and the minus side along both lines as a signal to be transmitted (hereinafter, “differential signal”). Is transmitted, and the differential signal is received by the differential amplifier circuit on the receiving side so that the common-mode noise generated by the signal transmission can be canceled.

  For example, consider the case of a differential line (also referred to as “stacked pair differential wiring”) having a port configuration as shown in FIGS. In FIGS. 11A and 11B, reference numeral 1 denotes a wiring (pair line) forming a pair of differential wirings, 3 denotes a reference ground, and 11 denotes an insulating layer (interlayer film). As shown in FIG. 11 (b), this differential line has two adjacent differential lines (differential ports 1 to 4), each paired on the plus side (+) and the minus side (−). The two lines (ports 1 to 8) 1 are as follows. In this case, the near-end / far-end crosstalk between two adjacent differential lines has the following relationship when expressed in the notation using the S parameter shown in FIGS. 18 (a) and 18 (b).

SDD31 = S51-S71-S73 + S53 (Formula 1)
SDD41 = S61−S81−S83 + S63 (Formula 2)
Here, when the SDD 31 and the SDD 41 input differential signals to one differential port 1 (ports 1 and 3) of the two differential lines, the other differential port 3 (ports 5 and 7). And near-end crosstalk appearing at the other differential port 4 (ports 6 and 8), respectively (see FIG. 18B). S51 to S81 and S53 to S83 correspond to differential signals that appear at ports 5 to 8 when differential signals are input to port 1 and port 3, respectively (see FIG. 18A).

  In the case of this differential line, if S51 and S71 are equal, the signals S73 and S53 are also equal because of the symmetry of the differential line, so that the near-end crosstalk SDD31 is theoretically set to 0 from Equation 1 above. Can do. Similarly, when S61 and S81 are equal, S83 and S63 are also equal due to the symmetry of the differential line. Therefore, the far-end crosstalk SDD41 can theoretically be zeroed from the above equation 2.

  With respect to the reduction in crosstalk of high-density and high-speed differential wiring, a diagonal differential line as shown in FIG. In FIG. 12, reference numeral 1 denotes a wiring (pair line) that becomes a pair of differential wirings, 3 denotes a reference ground, and 11 denotes an insulating layer (interlayer film). According to this, low crosstalk can be achieved by arranging one adjacent differential wiring so that the amount of crosstalk is the same as that of each pair of differential lines 1 and repeating the arrangement for canceling the crosstalk. High-density and high-speed differential wiring is realized. Patent Document 1 also proposes a stacked pair differential wiring as shown in FIG. In FIG. 13, reference numeral 1 denotes a wiring (pair line) forming a pair of differential wirings, 3 denotes a reference ground, and 11 denotes an insulating layer (interlayer film). In this configuration, high-density wiring can be configured.

  Patent Document 2 discloses a connector for differential signal transmission as shown in FIG. In FIG. 14, reference numerals 21 and 23 denote a pair of contacts, reference numerals 22 and 24 denote a pair of contacts arranged in parallel with a gap in the transverse direction with respect to the direction of the pair of contacts 21 and 23, and reference numeral 25 denotes a dielectric. The bodies 26 and 27 are hollow. According to the configuration of FIG. 14, in the wiring configuration of FIG. 13, in order to cancel the white arrows and the black arrows, the dielectric constant of the portions (cavities) 26 and 27 having a small distance is lowered and the effective distance is increased. is doing. Alternatively, the effective distance is shortened by increasing the dielectric constant of a portion having a large distance.

  Patent Document 3 also discloses a configuration as shown in FIG. According to this, by arranging the wirings 30 and 31 that form a pair of one differential wiring 28 and the wirings 29 and 32 that form a pair of the other differential wiring 28 to each other, the black arrow and the white arrow are equidistant from each other. The cancellation is realized.

  Moreover, although it is the same as that of the structure of FIG. 15, in patent document 4, the structure of a wired transmission path as shown in FIG. 16 is also disclosed. The wired transmission path shown in FIG. 16 includes first and second differential transmission lines, and the first differential transmission line includes two strip lines 34 and 35, and the second differential transmission line includes two It consists of strip lines 36, 37, and the strip lines 34, 35 are arranged at the same distance from both the strip lines 36, 37. In this case, the near-end and far-end crosstalk can be canceled even if the wires 34 to 37 constituting the differential transmission line are not square.

Further, Patent Document 5 discloses a flexible wiring board as shown in FIG. According to this, the coupling is weakened by providing the ground wiring 43 between the differential data lines 41 and 42 which are two adjacent differential lines and the differential clock line.
Japanese Patent Laid-Open No. 2005-101588 JP-A-2005-251552 JP 2007-67590 A JP 2003-258510 A JP 2006-41193 A

  However, in the configuration of Patent Document 1 (see FIG. 12), the crosstalk between the black arrows shown in FIG. 12 can be canceled, but the crosstalk between the white arrows cannot be canceled. Further, in the stacked pair differential wiring as shown in FIG. 13, a high-density wiring can be formed, but the crosstalk is not canceled because the distance between the white arrows and the black arrows is different.

  In the configuration of Patent Document 2 (see FIG. 14), the near-end crosstalk is mainly capacitive, and the far-end crosstalk is inductive. Crosstalk cannot be canceled at the same time. Further, since regions having different dielectric constants are provided between the differential lines, it is necessary to provide an extra inter-wiring distance, which is not good from the viewpoint of increasing the density.

  In the configuration of Patent Document 3 (see FIG. 15), since the distances themselves are equal, if the wires 30 to 33 are square, the near-end far-end crosstalk can be canceled. Will appear. Further, when the differential wiring is formed adjacent to each other, the cancel configuration is lost, and therefore it is necessary to form the adjacent differential wiring at a distance.

  Further, in the configuration of Patent Document 4 (see FIG. 16), when the differential wiring is formed further adjacent to each other, the cancel configuration is not used, so it is necessary to form the adjacent differential wiring at a distance.

  Further, in the configuration of Patent Document 5 (see FIG. 17), the coupling cannot be completely reduced to 0, and the near end and far end crosstalk cannot be simultaneously reduced to 0.

  An object of the present invention is to realize a low crosstalk high-speed and high-density differential wiring in which the near-end and far-end crosstalk of infinitely adjacent differential wirings is substantially zero within an allowable error range.

  In the present invention, the above problem is solved by adopting the following configuration.

  The first differential wiring is a stacked pair differential wiring having a differential wiring paired with a wiring having a wiring thickness smaller than the wiring width, and a reference ground of the wiring. A ground wiring is provided at a position near the reference ground.

  The second differential wiring includes a differential wiring paired with a wiring having a wiring thickness smaller than the wiring width, and a reference ground of the wiring, and the adjacent differential wiring pairs cross each other. In the stacked pair differential wiring, the ground wiring is provided at a position near the reference ground between the adjacent differential wirings.

  Preferably, the ground wiring is provided symmetrically in the vertical direction at a position near the upper and lower reference ground between the adjacent differential wirings. In addition, the wiring thickness of the wiring is set so that the near end crosstalk of the differential wiring can be canceled, and the distance between the ground wiring and the reference ground is the far end crosstalk of the differential wiring. It is set to be cancelable.

  The third differential wiring is a stacked pair differential wiring having a differential wiring paired with a wiring having a wiring thickness smaller than the wiring width, and a reference ground of the wiring. The region between the differential wires is located closer to the differential wires than the other regions of the reference ground.

  Preferably, in the reference ground region, upper and lower regions between adjacent differential wires are located closer to the differential wires than other regions of the reference ground.

  The fourth differential wiring is a single-ended wiring alternately arranged with the differential wiring in a stacked pair differential wiring having a differential wiring composed of a pair of wirings and a reference ground of the wiring. And the single-ended wiring is located at the center height of the differential wiring.

  According to the present invention, it is possible to realize a low-crosstalk high-speed and high-density differential wiring in which the near-end and far-end crosstalk of infinitely adjacent differential wirings is substantially zero within an allowable error range.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the stacked pair differential wiring will be described. However, the present invention is not limited to this, and is also applicable to a wiring board and wiring structure having a stacked pair differential wiring, a differential transmission path, and the like. These are possible and are within the scope of the present invention.

  In this embodiment, in the wiring configuration of the stacked pair differential wiring shown in FIG. 13, the near end crosstalk is canceled by changing the wiring thickness of the differential wiring, and the far end is provided by providing the ground wiring. A low crosstalk high-speed and high-density differential wiring is realized in which the crosstalk is canceled and the near-end far-end crosstalk of the infinitely adjacent differential wiring is substantially zero within an allowable error range.

  As another embodiment, in the wiring configuration of the stacked pair differential wiring shown in FIG. 13, a single-ended wiring is arranged between the adjacent differential wirings, so that the differential wirings infinitely close to each other are arranged. A low crosstalk high-speed and high-density differential wiring is realized in which the far-end crosstalk is substantially zero within an allowable error range.

  Examples of the present invention will be specifically described below.

  First, a first embodiment of the present invention will be described with reference to FIGS.

  The differential wiring according to the present embodiment shown in FIG. 1 has the same stacked pair differential wiring configuration as that of FIG. 13, that is, differential signals that are inverted to the positive side (+) and the negative side (−). A pair of differential wirings to be transmitted is provided, and a wiring 1 having a width w (mm) and a thickness t (mm) is disposed at a distance d2 in the thickness direction (vertical direction).

  The wirings 1 forming a pair of differential wirings are arranged adjacent to each other in parallel in the width direction (horizontal direction) at a predetermined interval (distance between lines) d1, thereby constituting adjacent differential wirings. Adjacent differential wirings are arranged in an insulating layer (interlayer film) 11 having a dielectric constant (relative dielectric constant) εr. The insulating layer 11 is sandwiched between reference grounds 3 above and below in the thickness direction (vertical direction) in the drawing. The reference ground 3 and the differential wiring are separated by a predetermined distance d3 (mm).

  In the present embodiment, in addition to this, at a predetermined position (in the center in the example in the figure) between the lines in the width direction of the wiring 1 which is a pair of differential wirings, the position is closer to the upper and lower reference grounds 3 in the thickness direction. Each is provided with a ground wiring 2. The ground wiring 2 is arranged at a predetermined distance d4 (mm) from the reference ground 3.

  Next, the operation and effect of the present embodiment will be described in comparison with a comparative example having no ground wiring.

  FIG. 2 shows a differential wiring of a comparative example. This configuration is the same as the wiring configuration shown in FIG.

  FIG. 3 shows a case where typical dimensions (w = 0.15 mm, t = 0.025 mm, d2 = 0.14 mm, d3 = 0.086 mm) are applied to the vertical axis in the configuration of the comparative example shown in FIG. It is a graph which shows the value of SDD11, SDD21, SDD31, SDD41, S61, S81, S51, S71 of this, and shows the distance d1 (mm) between the lines of the differential wiring adjacent to a horizontal axis. Each value on the vertical axis of the graph shown in FIG. 3 indicates a frequency of 10 GHz (lower side) and 20 GHz (upper side). In this example, the dielectric constant εr of the insulating layer 11 is εr = 3.7.

  The configuration of the differential port of the adjacent differential wiring shown in FIGS. 1 and 2 is the same as that of FIG. 11B described above, and the notation using the S parameter is the same as that of FIG. It is the same. Here, the SDD 11 and the SDD 21 are reflected when a differential signal is input to one differential port 1 (ports 1 and 3) shown in FIG. 11B of two adjacent differential lines. A differential signal appearing at the differential port 1 and a differential signal transmitted and appearing at the other differential port 2 (ports 2 and 4) are respectively shown (see FIG. 18B). Further, when a differential signal is input to one differential port 1 (ports 1 and 3) of two differential lines, the SDD 31 and the SDD 41 are connected to the other differential port 3 (ports 5 and 7). The near-end crosstalk that appears and the far-end crosstalk that appears at the other differential port 4 (ports 6 and 8) are respectively shown (see FIG. 18B). Further, S51 to S81 correspond to the differential signals that appear at ports 5 to 8 when a differential signal is input to port 1 (see FIG. 18A).

  FIG. 4 shows a similar graph when the same dimensions as those of the comparative example shown in FIG. 3 are applied to the configuration of the present embodiment shown in FIG. The dimensions used are the same as those in FIG. 2 except that two ground wires are added. In this case, the distance d4 between the ground wiring 2 and the reference ground 3 is d4 = 0.13 mm.

  3 and FIG. 4, for example, when d1 = 0.2 mm, the near-end crosstalk SDD31 of the adjacent differential wiring does not change much, but the far-end crosstalk SDD41 of the adjacent differential wiring is S61. And S81 were confirmed to be further improved. At this time, it was confirmed that the SDD 11 did not change so much and the influence of the impedance mismatch due to the additional ground wiring 2 was small.

  5 and 6, in the configuration of this embodiment, the vertical axis indicates the crosstalk amount (dB) when d1 = 0.2 mm and the frequency is 10 GHz, and the horizontal axis indicates the relationship between the ground wiring 2 and the reference ground layer 3. It is a graph which shows distance d4 (mm) as a parameter.

  As shown in FIG. 5, in the present example, the addition of the ground wiring 2 increased S61 and S81, and it was confirmed that the increase rate of S61 was larger than S81. On the other hand, as shown in FIG. 6, S51 and S71 decreased, and it was confirmed that the difference in the reduction ratio between the two was small. In the configuration of this example, it was confirmed that S61 and S81 had a small S61 and S51 and S71 had a large S51 when there was no ground wiring 2 as in the comparative example. Then, as shown in FIG. 5, S61 and S81 intersect when the distance d4 between the ground wiring 2 and the reference ground 3 is 0.13 mm, and it is confirmed that the SDD 41 is 0 at the intersection. . When the thickness t is smaller than the width w in the normal differential wiring configuration, it is considered that such a magnitude relationship is obtained.

  What should be noted here is that when the distance d4 between the ground wiring 2 and the reference ground 3 is small, there is a cross point between S61 and S81. The difference between the two is small, even if the ground 2 is arranged, the original differential wiring does not need to increase the distance between adjacent lines, and only the SDD 41 changes depending on the ground wiring 2, so the near-end crosstalk is different. If it is set to 0 by this means, both can be set to 0. Further, when S61 is larger than S81, it is necessary to have one ground wiring 2 in the center. In this case, it is necessary to increase the distance from the adjacent differential wiring, which is not good from the viewpoint of high density. The thickness t is preferably smaller than the wiring width w.

  7 and 8, after changing the wiring thickness t in the wiring configuration shown in FIG. 2 so that the near-end crosstalk becomes 0, the ground wiring 2 is added as in the wiring configuration shown in FIG. The result of the case is shown. Here, the wiring thickness t is changed because the influence of the wiring thickness t on the impedance is smaller than that of other parameters.

  As a result, it was confirmed that when the wiring thickness t was t = 0.013 mm, the SDD 31 was almost zero. In this case, the wiring width w is a rectangle larger than the thickness t. In this case, S61 and S81 are larger in S61. At this time, d1 is 0.2 mm.

  When the ground wiring 2 is added in this state, as shown in FIGS. 7 and 8, the SDD 31 does not change and is 0, and when the distance d4 from the reference ground 3 is 0.23 mm, the SDD 41 becomes 0. Was confirmed. The change of SDD11 is small.

  As described above, the following was confirmed by the wiring configuration of the stacked pair differential wiring provided with the ground wiring of this example.

  1) SDD31 and SDD41 are set to zero.

  2) Since the cross point exists when the distance d4 between the ground wiring 2 and the reference ground layer 3 is small, the difference in impedance is small compared to the case where there is no ground wiring 2, and the difference in SDD 11 is small.

  3) Even if the ground wiring 2 is arranged, the original differential wiring does not need to increase the distance between adjacent lines, so that high density can be maintained.

  4) Since this configuration can increase the number of adjacent differential wirings infinitely, high-density wiring can be realized.

  Therefore, according to the present embodiment, it is possible to realize a low-crosstalk high-speed and high-density differential wiring in which the near-end and far-end crosstalk of the infinitely adjacent differential wiring is substantially zero within the allowable error range. .

  The configuration of the present embodiment can also be applied to the configuration of FIG. 15 where the wiring thickness t is smaller than the wiring width w. That is, in a stacked pair differential wiring in which two pairs of differential wirings having a wiring thickness t smaller than the wiring width w are arranged in a cross, two or more reference wirings near the upper and lower reference grounds between adjacent differential wirings. The present invention can also be applied to a configuration in which ground wirings are provided symmetrically in the vertical direction.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the differential wiring according to the present embodiment shown in FIG. 9, in the configuration of FIG. 1, the ground wiring is not provided, but instead the projection 3a is provided on the reference ground 3, so that the infinite number is the same as in the first embodiment. A low crosstalk high-speed and high-density differential wiring is realized in which the near-end and far-end crosstalk of the differential wiring adjacent to is substantially zero within an allowable error range.

  In this embodiment, an extra layer is eliminated, and a 4-layer substrate is used instead of a 6-layer substrate. As a manufacturing method of the differential wiring according to the present embodiment, a method of manufacturing without forming an interlayer film between the reference ground layer and the ground wiring, or etching the interlayer film, and then the reference ground layer A method of forming a film can be considered.

  In this embodiment, the convex portion 3a is provided on the reference ground 3 instead of the ground wiring. However, the present invention is not limited to this. In short, in stacked pair differential wiring, where the wiring thickness is smaller than the wiring width, the upper and lower areas between adjacent differential wirings in the reference ground area are different from the other areas in the reference ground. If it exists in the side, it is applicable.

  Next, a third embodiment of the present invention will be described with reference to FIG.

  The differential wiring according to the present embodiment shown in FIG. 10 is the same as the stacked pair differential wiring shown in FIG. 13 except that the ground wiring in FIG. 1 and the convex portion of the reference ground in FIG. Instead, the single-end wiring 4 is arranged at the center of the position between the lines in the width direction of the wiring 1 that forms a pair of adjacent differential wirings. That is, the differential wiring and the single end wiring 4 are alternately arranged, and the single end wiring 4 is located at the center height of the differential wiring. By doing so, as in the first and second embodiments, the low-crosstalk high-speed high-density difference in which the near-end far-end crosstalk of the infinitely adjacent differential wiring is substantially zero within the allowable error range. Realizes dynamic wiring.

  The present invention can be applied to applications such as a differential transmission line, a wiring board, and a wiring structure using the stacked pair differential wiring in addition to the stacked pair differential wiring.

It is a schematic sectional drawing which shows the structure of the differential wiring which concerns on 1st Example of this invention. It is a schematic sectional drawing which shows the structure of the differential wiring which concerns on a comparative example. In the comparative example, (a) is a graph showing the relationship between the SDD11, SDD21, SDD41, S61, and S81 and the distance between adjacent differential wiring lines, and (b) is adjacent to the SDD11, SDD21, SDD31, S51, and S71. It is a graph which shows the relationship with the distance between lines of differential wiring. In the first embodiment, (a) is a graph showing the relationship between SDD11, SDD21, SDD41, S61, S81 and the distance between adjacent differential wiring lines, and (b) is SDD11, SDD21, SDD31, S51, S71. Is a graph showing the relationship between the distance between adjacent lines of differential wiring. In a 1st Example, it is a graph which shows the relationship between SDD41, S61, S81 and the distance between a ground wiring and a reference ground. In a 1st Example, it is a graph which shows the relationship between SDD31, S51, S71 and the distance between a ground wiring and a reference ground. In the first embodiment, the relationship between the SDD 41, S61, and S81 when a ground wiring is added after changing the wiring thickness to near-end crosstalk to 0 and the distance between the ground wiring and the reference ground. It is a graph which shows. In the first embodiment, the relationship between the SDD 31, S 51, S 71 and the distance between the ground wiring and the reference ground when the ground wiring is added after the near-end crosstalk is set to 0 by changing the wiring thickness. It is a graph which shows. It is a schematic sectional drawing which shows the structure of the differential wiring which concerns on 2nd Example of this invention. It is a schematic sectional drawing which shows the structure of the differential wiring which concerns on the 3rd Example of this invention. (A) is a schematic sectional drawing which shows the structure of stacked pair differential wiring, (b) is a schematic perspective view explaining the port structure. 6 is a schematic cross-sectional view showing a configuration of a diagonal differential line of Patent Document 1. FIG. 10 is a schematic cross-sectional view showing a configuration of a stacked pair differential wiring in Patent Document 1. FIG. 10 is a schematic cross-sectional view showing a configuration of a differential signal transmission connector of Patent Document 2. FIG. 10 is a schematic perspective view showing a configuration of a differential wiring arranged in a cross manner in Patent Document 3. FIG. It is a schematic perspective view which shows the structure of the wired transmission path of patent document 4. It is a schematic sectional drawing which shows the structure of the flexible wiring board of patent document 5. It is a figure explaining the notation using the S parameter of stacked pair differential wiring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wire which becomes a pair of differential wiring 2 Ground wiring 3 Reference ground 3a Convex part 4 Single end wiring

Claims (10)

Differential wiring paired with wiring having a wiring thickness smaller than the wiring width; and
In a stacked pair differential wiring having a reference ground of the wiring,
A differential wiring, wherein a ground wiring is provided at a position near the reference ground between the adjacent differential wirings. Differential wiring paired with wiring having a wiring thickness smaller than the wiring width; and
A reference ground for the wiring;
In a stacked pair differential wiring formed by arranging wirings that form a pair of adjacent differential wirings to cross each other,
A differential wiring, wherein a ground wiring is provided at a position near the reference ground between the adjacent differential wirings.   The differential wiring according to claim 1, wherein the ground wiring is provided symmetrically in the vertical direction at a position near the reference ground between the adjacent differential wirings. The wiring thickness of the wiring is set so that the near-end crosstalk of the differential wiring can be canceled,
4. The difference according to claim 1, wherein the distance between the ground wiring and the reference ground is set such that far-end crosstalk of the differential wiring can be canceled. 5. Dynamic wiring. Differential wiring paired with wiring having a wiring thickness smaller than the wiring width; and
In a stacked pair differential wiring having a reference ground of the wiring,
The differential wiring, wherein a region between the adjacent differential wirings in the reference ground region is present at a position closer to the differential wiring than other regions of the reference ground.   6. The reference ground region, wherein upper and lower regions between adjacent differential wires are located closer to the differential wires than other regions of the reference ground. Differential wiring. Differential wiring composed of paired wiring; and
In a stacked pair differential wiring having a reference ground of the wiring,
Having single-ended wiring alternately arranged with the differential wiring;
The differential wiring is characterized in that the single-ended wiring is located at a central height of the differential wiring.   A wiring board comprising the differential wiring according to claim 1.   A wiring structure comprising the differential wiring according to claim 1.   A differential transmission line using the differential wiring according to any one of claims 1 to 7.

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