JP2024038529A - wiring board - Google Patents

Abstract

The present invention provides a wiring board capable of suppressing local fluctuations in characteristic impedance. A wiring board 1 having a strip structure includes a signal line 21, an upper ground layer 50 facing the signal line 21 via an upper base film 40, and an upper ground layer 50 opposite to the signal line 21. A lower ground layer 60 is located on the side and faces the signal line 21 via the lower base film 40, and the upper ground layer 50 has a mesh shape having a plurality of periodically arranged openings 55. 51, and the lower ground layer 60 has a mesh shape 61 having a plurality of periodically arranged openings 65, and in a plan view, the center CP1 of the opening 55 and the center CP2 of the opening 65 are They are out of alignment with each other. [Selection diagram] Figure 4

Description

The present invention relates to a wiring board.

A flexible printed wiring board (FPC) with a strip structure includes a signal wiring layer having signal lines, and a pair of ground layers laminated on both sides of the signal wiring layer with an insulator layer in between (for example, as disclosed in the patent (See Reference 1).

JP2019-192786A

In the above flexible printed wiring board, the shape of the mesh part of the upper ground layer is the same as the shape of the mesh part of the lower ground layer, and the upper and lower grounds are There are layers upon layers. Therefore, the position where the intersection of the mesh part of the upper ground layer overlaps with the signal line coincides with the position where the intersection of the mesh part of the lower ground layer overlaps with the signal line, and the characteristic impedance of the signal line is It will drop. On the other hand, the position where the opening in the mesh part of the upper ground layer overlaps with the signal line coincides with the position where the opening in the mesh part of the lower ground layer overlaps with the signal line, and the characteristic impedance of the signal line is It gets expensive.

In this way, in the above flexible printed wiring board, the upper and lower ground layers have mesh portions of the same shape and are stacked so that the mesh portions match, so the characteristic impedance of the signal line is locally large. There is a problem that the transmission characteristics may deteriorate due to fluctuations.

The problem to be solved by the present invention is to provide a wiring board that can suppress local fluctuations in characteristic impedance.

[1] The wiring board according to the present invention is a wiring board having a strip structure, and includes a signal line, a first ground layer facing the signal line via a first insulating layer, and a first ground layer facing the signal line via a first insulating layer. a second ground layer located on the opposite side of the first ground layer and facing the signal line via a second insulating layer, the first ground layer having a periodicity of The second ground layer has a first mesh shape having a plurality of first openings arranged periodically, and the second ground layer has a second mesh shape having a plurality of second openings arranged periodically. In the wiring board, the center of the first opening and the center of the second opening are shifted from each other in plan view.

[2] In the above invention, the arrangement direction of the first openings in the first mesh shape and the arrangement direction of the second openings in the second mesh shape are substantially the same, and The pitch between the openings may be substantially the same as the pitch between the second openings.

[3] In the above invention, the first mesh shape is formed by crossing the first and second thin lines with each other, and the second mesh shape is formed by crossing the third and fourth thin lines with each other. The cross angle of the first thin wire with respect to the signal line is substantially the same as the cross angle of the third thin wire with respect to the signal line, and the cross angle of the third thin wire with respect to the signal line is substantially the same. The intersection angle of the second thin wire and the intersection angle of the fourth thin wire with respect to the signal line are substantially the same, and the pitch between the first thin wires and the pitch between the third thin wires are substantially the same. The pitch between the second thin wires and the pitch between the fourth thin wires may be substantially the same.

[4] In the above invention, the widths of the first to fourth thin lines may be within a range of ±20% with respect to the average width of the first to fourth thin lines.

[5] In the above invention, the first ground layer has a first intersection where the first and second thin lines intersect, and the second ground layer has a first intersection where the first and second thin lines intersect, and the second ground layer has a first intersection where the first and second thin lines intersect. The thin wires have a second intersection where the thin lines intersect, and in plan view, the first intersection is arranged so that the first intersection does not overlap the third and fourth thin lines. 2, and in plan view, the second intersection is located within the first opening so that the second intersection does not overlap with the first and second thin lines. , and may satisfy the following formula (1).

0.2×P ₀ ≦D ₀ ≦0.8×P ₀ …(1)

However, in the above equation (1), P ₀ is a pitch along the extending direction of the signal line between the first intersections that are adjacent to each other through the first opening, and D ₀ is the amount of deviation of the second intersection with respect to the first intersection along the extending direction of the signal line.

[6] In the above invention, the following formula (2) may be satisfied.

0.4×P ₀ ≦D ₀ ≦0.6×P ₀ …(2)

According to the present invention, in a wiring board having a strip structure, the center of the first mesh-shaped first opening of the first ground layer and the second mesh-shaped second opening of the second ground layer Since the centers of the signal lines are shifted from each other, local fluctuations in the characteristic impedance of the signal line can be suppressed.

FIG. 1 is a plan view showing a part of a wiring board in an embodiment of the present invention. FIG. 2 is a sectional view taken along line II-II in FIG. 1. FIG. 3 is a sectional view taken along line III-III in FIG. 1. FIG. 4 is a plan view showing the lower ground layer in the embodiment of the present invention, and is a diagram for explaining the positional relationship between the upper ground layer and the lower ground layer.

Embodiments of the present invention will be described below based on the drawings.

1 is a plan view showing a part of a wiring board in an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II in FIG. 1, and FIG. 3 is a sectional view taken along line III-III in FIG. FIG. Further, FIG. 4 is a plan view showing the lower ground layer in the embodiment of the present invention, and is a diagram for explaining the positional relationship between the upper ground layer and the lower ground layer.

The printed wiring board 1 in this embodiment is a flexible printed wiring board (FPC) having a strip structure. As shown in FIGS. 1 to 4, this printed wiring board 1 includes a lower base film 10, a signal layer 20, an adhesive layer 30, an upper base film 40, an upper ground layer 50, and a lower ground layer. It is equipped with 60. In addition, in FIG. 4, the lower ground layer 60 is shown by a solid line, and the upper ground layer 50 is shown by a broken line.

The lower base film 10 in this embodiment corresponds to an example of the "second insulating layer" in the present invention, and the upper base film 40 in this embodiment corresponds to an example of the "first insulating layer" in the present invention. . Further, the upper ground layer 50 in this embodiment corresponds to an example of the "first ground layer" in the present invention, and the lower ground layer 60 in this embodiment corresponds to an example of the "second ground layer" in the present invention. Equivalent to.

The lower base film 10 is a flexible film. This lower base film 10 is made of an electrically insulating material such as a resin material. Although not particularly limited, examples of the material constituting the lower base film 10 include polyimide (PI), liquid crystal polymer (LCP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyetherimide (PEI). , polyetheretherketone (PEEK), and aramid.

A signal layer 20 is formed on the upper surface 11 of this lower base film 10. The signal layer 20 includes a signal line 21 and a pair of ground lines 22 and 23. The signal line 21 in this embodiment corresponds to an example of a "signal line" in the present invention. Note that the number of signal lines 21 included in the signal layer 20 is not particularly limited, and the signal layer 20 may include a plurality of signal lines. Further, depending on the transmission characteristics required of the signal line 21, the pair of ground lines 22 and 23 may be omitted.

As shown in FIG. 1, the signal line 21 extends linearly along the X direction in the figure. The signal line 21 in this embodiment is a signal line for single-end signal transmission (single-end line), but is not particularly limited thereto. The signal lines included in the signal layer 20 may be signal lines for differential signal transmission (differential pair lines).

The pair of ground lines 22 and 23 are arranged on both sides of the signal line 21, and have a width wider than the width of the signal line 21. Further, the pair of ground lines 22 and 23 extend in substantially the same direction as the signal line 21 (X direction in the figure), and the signal line and the ground lines 22 and 23 are substantially parallel to each other. Extending. The distance between one ground line 22 and the signal line 21 is substantially the same as the distance between the other ground line 23 and the signal line. Although not particularly shown, these ground lines 22 and 23 are connected to ground layers 50 and 60 via through holes (not particularly shown), and have the function of shielding noise generated from the signal line 21 and noise entering from the outside. have. Note that the widths of the ground lines 22 and 23 are not particularly limited to the above, and may be narrower than the width of the signal line 21.

The signal layer 20 including the signal line 21 and the ground lines 22 and 23 is made of a conductive material such as metal or carbon. Examples of the metal constituting the signal layer 20 include copper, silver, and gold. In this embodiment, copper is used as a material constituting the signal layer 20. Although not particularly limited, this signal layer 20 is formed using a method such as a subtractive method or a semi-additive method, and is formed by etching a copper foil laminated on the lower base film 10 into a predetermined shape. has been done.

As shown in FIGS. 2 and 3, an upper base film 40 is laminated on the lower base film 10 so as to cover the signal layer 20. This upper base film 40 is a film that is flexible and electrically insulating, like the lower base film 10 described above. As the material constituting the upper base film 40, the same material as the material constituting the lower base film 10 mentioned above can be exemplified. Note that the upper base film 40 may be made of the same material as the material that makes up the lower base film 10, or may be made of a different material from the material that makes up the lower base film 10.

This upper base film 40 is fixed to the lower base film 10 via an adhesive layer 30. The adhesive constituting this adhesive layer 30 is not particularly limited, but an adhesive made of modified polyphenylene ether resin (m-PPE) can be used. Note that as the adhesive constituting the adhesive layer 30, an epoxy adhesive, an acrylic adhesive, or the like may be used.

An upper ground layer 50 is formed on the upper surface 41 of this upper base film 40. Note that a coverlay may be laminated on the upper surface 41 of the upper base film 40 so as to cover the upper ground layer 50.

As shown in FIG. 1, this upper ground layer 50 has an overall band-like shape extending linearly along the X direction in the figure, and the center line of the upper ground layer 50 in plan view. is arranged so as to substantially coincide with the center line of the signal line 21. Further, this upper ground layer 50 has a mesh shape 51 having a plurality of openings 55 arranged periodically. This upper ground layer 50 has a function of shielding noise generated from the signal line 21 and noise entering from the outside.

This upper ground layer 50 includes two types of thin wires 52 and 53 forming a mesh shape 51. The mesh shape 51 in this embodiment corresponds to an example of the "first mesh shape" in the present invention, the thin wire 52 in this embodiment corresponds to an example of the "first thin wire" in the present invention, and The thin wire 53 corresponds to an example of a "second thin wire" in the present invention.

One of the thin wires 52 has a width W ₁ and extends linearly along the first direction U. On the other hand, the other thin wire 53 has a width W ₂ and extends linearly along a second direction V that is substantially orthogonal to the first direction U. In this embodiment, the width W ₁ of one thin line 52 and the width W ₂ of the other thin line 53 are substantially the same (W ₁ =W ₂ ). In this embodiment, "substantially the same" means that the error is within ±5%.

Further, the first direction U is 52° with respect to the extending direction of the signal line 21 (X direction in the figure), whereas the second direction V is -38° to the direction. That is, in this embodiment, the crossing angle θ ₁ of one thin wire 52 with respect to the signal line 21 is 52° (θ ₁ =52°), whereas the crossing angle θ 1 of the other thin wire 53 with respect to the signal line 21 is 52° (θ 1 =52°). ₂ is −38° (θ ₂ =−38°). Note that in this embodiment, a clockwise rotation direction with respect to the reference line (+X direction in this example) is indicated by a positive angle, and a counterclockwise rotation direction with respect to the reference line is indicated by a negative angle.

Further, the plurality of thin wires 52 are arranged at substantially equal intervals along the second direction V, and the pitch (distance between centers) between the mutually adjacent thin wires 52 along the second direction V is It is _P1 . Similarly, the plurality of thin wires 53 are arranged at substantially equal intervals along the first direction U, and the pitch between adjacent thin wires 53 along the first direction U is _P2 . ing. In this embodiment, the pitch P ₁ of the thin wires 52 and the pitch P ₂ of the thin wires 53 are substantially the same (P ₁ =P ₂ ).

Therefore, the thin wires 52 and 53 intersect with each other at the intersection 54, forming a mesh shape 51 having a plurality of openings 55. Each intersection 54 has a square shape, and each opening 55 also has a square shape. The mesh shape 51 of the upper ground layer 50 has a plurality of openings 55 arranged along the first and second directions U and V. That is, the arrangement directions of the openings 55 in the mesh shape of the upper ground layer 50 are the first and second directions U and V. Incidentally, the pitch along the X direction in the figure between the intersection parts 54 adjacent to each other with the opening 55 in between is _P0 .

Further, the upper ground layer 50 includes a pair of outer edge lines 56 that define both edges (upper and lower edges in the figure) of the band-like shape. This outer edge line 56 extends linearly along the X direction in the figure, and connects the ends of the thin wires 52 and 53 forming the mesh shape 51 along the X direction in the figure. Note that the upper ground layer 50 does not need to include the outer edge line 56.

Note that the width W ₁ of the thin line 52 and the width W ₂ of the thin line 53 may be different. Further, the first and second directions U and V are not particularly limited to the above. Although not particularly limited, for example, the first direction U may be at 45° with respect to the extending direction of the signal line 21, while the second direction V may be at -45° with respect to the signal line 21. good.

Furthermore, the intersection angle between the first direction U and the second direction V is not limited to 90°. Furthermore, the pitch P ₁ of the thin wires 52 and the pitch P ₂ of the thin wires 53 may be different. When the intersection angle between the first direction U and the second direction V is not a right angle, or when the pitch P ₁ of the thin wires 52 and the pitch P ₂ of the thin wires 53 are different, the shape of the opening 55 is a rectangle other than a square. becomes.

As the material constituting the upper ground layer 50, the same material as the material constituting the signal layer 20 described above can be exemplified. Note that the upper ground layer 50 may be made of the same material as the signal layer 20, or may be made of a different material from the signal layer 20. Further, as a method for manufacturing the upper ground layer 50, a method similar to the method for manufacturing the signal layer 20 described above can be exemplified. Note that the upper ground layer 50 may be formed by the same manufacturing method as the signal layer 20, or may be formed by a manufacturing method different from the manufacturing method of the signal layer 20.

On the other hand, the lower ground layer 60 is formed on the lower surface 12 of the lower base film 10, as shown in FIGS. 2 and 3. Note that a coverlay may be laminated on the lower surface 12 of the lower base film 10 so as to cover the lower ground layer 60.

As shown in FIG. 1, the lower ground layer 60 has an overall band-like shape extending linearly along the X direction in the figure, and has a width substantially equal to the width of the upper ground layer 50. It has a width of Further, the lower ground layer 60 is arranged such that the center line of the lower ground layer 60 substantially coincides with the center line of the signal line 21 in plan view. Further, as shown in FIG. 4, the lower ground layer 60 has a mesh shape 61 having a plurality of periodically arranged openings 65. This lower ground layer 60 has a function of shielding noise generated from the signal line 21 and noise entering from the outside.

This lower ground layer 60 includes two types of thin wires 62 and 63 forming a mesh shape 61. The mesh shape 61 in this embodiment corresponds to an example of the "second mesh shape" in the present invention, and the thin wire 62 in this embodiment corresponds to an example of the "third thin wire" in the present invention. The thin line 63 corresponds to an example of the "fourth thin line" in the present invention.

One of the thin wires 62 has a width W ₃ and extends linearly along the first direction U. On the other hand, the other thin wire 63 has a width W ₄ and extends linearly along the second direction V. In this embodiment, the width W ₃ of one thin line 62 and the width W ₄ of the other thin line 63 are substantially the same (W ₃ =W ₄ ). Note that the width W ₃ of the thin line 62 and the width W ₄ of the thin line 63 may be different.

Further, the plurality of thin wires 62 are arranged at substantially equal intervals along the second direction V, and the pitch between mutually adjacent thin wires 62 along the second direction V is _P3 . There is. Similarly, the plurality of thin wires 63 are also arranged at substantially equal intervals along the first direction U, and the pitch between adjacent thin wires 63 along the first direction U is _P4 . ing. In this embodiment, the pitch P ₃ of the thin wires 62 and the pitch P ₄ of the thin wires 63 are substantially the same (P ₃ =P ₄ ).

Therefore, the thin wires 62 and 63 intersect with each other at the intersection 64, forming a mesh shape 61 having a plurality of openings 65. Each intersection 64 has a square shape, and each opening 65 also has a square shape. Furthermore, the mesh shape 61 of the lower ground layer 60 has an array in which a plurality of openings 65 are arranged along the first and second directions U and V. That is, the arrangement directions of the openings 65 in the mesh shape of the lower ground layer 60 are the first and second directions U and V.

Further, the lower ground layer 60 includes a pair of outer edge lines 66 that define both edges (upper and lower edges in the figure) of the band-like shape. This outer edge line 66 extends linearly along the X direction in the figure, and connects the ends of the thin wires 62 and 63 forming the mesh shape 61 along the X direction in the figure. Note that the lower ground layer 60 does not need to include the outer edge line 66.

In this embodiment, the width W ₃ of one thin line 62 of the lower ground layer 60 and the width W ₁ of one thin line 52 of the upper ground layer 50 are substantially the same (W ₃ =W ₁ ), the width W ₄ of the other thin line 63 of the lower ground layer 60 and the width W ₂ of the other thin line 53 of the upper ground layer 50 are substantially the same (W ₄ =W ₂ ). Therefore, all the widths W ₁ to W ₄ of the thin lines 52 and 53 of the upper ground layer 50 and the thin lines 62 and 63 of the lower ground layer 60 are substantially the same (W ₁ =W ₂ =W ₃ = _W4 ).

Note that the relationship between the widths W ₁ to W ₄ of the thin lines 52, 53, 62, and 63 is not particularly limited to the above, and the widths W _{1 to W 4 of the thin lines 52, 53, 62, and 63 are the same as the widths W 1} to W ₄ of the thin lines 52, 53, 62, and ₆₃ . It may be included within the range of ±20% of the average value W _ave of W ₄ . That is, the widths W ₁ to W ₄ of the thin lines 52, 53, 62, and 63 may satisfy the following expressions (3) to (7).
W _ave ×0.8≦W ₁ ≦W _ave ×1.2 (3)
W _ave ×0.8≦W ₂ ≦W _ave ×1.2 (4)
W _ave ×0.8≦W ₃ ≦W _ave ×1.2…(5)
W _ave ×0.8≦W ₄ ≦W _ave ×1.2…(6)
W _ave = (W ₁ +W ₂ +W ₃ +W ₄ )/4...(7)

Further, the pitch P ₃ between one of the thin wires 62 of the lower ground layer 60 is substantially the same as the pitch P ₁ between one of the thin wires 52 of the upper ground layer 50 (P ₃ =P ₁ ). , the pitch P ₄ between the other thin wires 63 of the lower ground layer 60 is substantially the same as the pitch P ₂ between the other thin wires 53 of the upper ground layer 50 (P ₄ =P ₂ ). That is, the pitch P 3 between the openings 65 adjacent to each other along the second direction V in the lower ground layer 60 is the same as the pitch P ₃ between the openings 55 adjacent to each other along the second direction V in the upper ground layer 50. The pitch P ₄ between mutually adjacent openings 65 along the first direction U in the lower ground layer 60 is substantially the same as _the pitch P 1 in the first direction U in the upper ground layer 50 . The pitch _P2 between adjacent openings 55 along U is substantially the same. Therefore, all the pitches P ₁ to P ₄ of the thin wires 52 and 53 of the upper ground layer 50 and the thin wires 62 and 63 of the lower ground layer 60 are substantially the same (P ₁ =P ₂ =P ₃ = _P4 ).

In addition to the above, the crossing angle θ ₃ of one thin wire 62 with respect to the signal line 21 is substantially the same as the crossing angle θ ₁ of one thin wire 52 of the upper ground layer 50 (θ ₃ =θ ₁ ). At the same time, the crossing angle θ ₄ of the other thin wire 63 with respect to the signal line 21 is also substantially the same as the crossing angle θ ₂ of the other thin wire 53 of the upper ground layer 50 (θ ₄ =θ ₂ ). That is, the direction in which the openings 55 in the mesh shape 51 of the upper ground layer 50 are arranged is substantially the same as the direction in which the openings 65 in the mesh shape 61 in the lower ground layer 60 are arranged. Therefore, in this embodiment, the mesh shape 51 of the upper ground layer 50 and the mesh shape 61 of the lower ground layer 60 have substantially the same shape.

In this embodiment, the upper ground layer 50 and the lower ground layer 60 are arranged so that the center CP ₁ of the opening 55 of the upper ground layer 50 and the center CP ₂ of the opening 65 of the lower ground layer 60 are shifted from each other. is located. Although not particularly limited, as shown in FIG. 4, in plan view, the center _CP2 of the opening 65 of the lower ground layer 60 is in the +X direction in the figure with respect to the center _CP1 of the opening 55 of the upper ground layer 50. In the case where there is a deviation _D0 along the line, it is preferable that the following equation (8) is satisfied, and it is more preferable that the following equation (9) is satisfied.

0.2×P ₀ ≦D ₀ ≦0.8×P ₀ …(8)

0.4×P ₀ ≦D ₀ ≦0.6×P ₀ …(9)

However, in the above equations (8) and (9), P ₀ is the pitch between the intersections 54 adjacent to each other via the openings 55 in the upper ground layer 50, and is the pitch along the X direction in the figure. It is. In other words, this P ₀ is along the direction in which the signal line 21 extends at an angle (θ ₁ -45°) obtained by subtracting 45° from the intersection angle θ ₁ with respect to the direction in which the signal line 21 extends (X direction in the figure). This is the pitch between mutually adjacent intersections 54, and is the pitch along the X direction in the figure. Further, D ₀ is the amount of deviation of the intersection 64 of the lower ground layer 60 with respect to the intersection 54 of the upper ground layer 50, and is the amount of deviation along the X direction in the figure.

By arranging the upper ground layer 50 and the lower ground layer 60 with the center CP ₂ of the opening 65 of the lower ground layer 60 being shifted from the center CP ₁ of the opening 55 of the upper ground layer 50 in this way, as shown in FIG. As shown in FIG. 3, the intersection 54 of the upper ground layer 50 is located within the opening 65 of the lower ground layer 60 so that the intersection 54 does not overlap the thin lines 62, 63 of the lower ground layer 60. Further, as shown in FIG. 3, the intersection 64 of the lower ground layer 60 is located within the opening 55 of the upper ground layer 50 so that the intersection 64 does not overlap the thin lines 52, 53 of the upper ground layer 50. ing.

As the material constituting the lower ground layer 60, the same material as the material constituting the signal layer 20 described above can be exemplified. Note that the lower ground layer 60 may be made of the same material as the signal layer 20, or may be made of a different material from the signal layer 20. Further, as a method for manufacturing the lower ground layer 60, a method similar to the method for manufacturing the signal layer 20 described above can be exemplified. Note that the lower ground layer 60 may be formed by the same manufacturing method as the signal layer 20, or may be formed by a manufacturing method different from the manufacturing method of the signal layer 20.

As described above, in the present embodiment, in the printed wiring board 1 having a strip structure, the center CP ₁ of the opening 55 of the mesh shape 51 of the upper ground layer 50 and the center of the opening 65 of the mesh shape 61 of the lower ground layer 60 CP ₂ are shifted from each other. As a result, the intersection 54 of the upper ground layer 50 and the intersection 64 of the lower ground layer 60 do not match, the intersection 54 of the upper ground layer 50 overlaps the opening 65 of the lower ground layer 60, and the lower ground Since the intersection 64 of the layer 60 overlaps the opening 55 of the upper ground layer 50, local fluctuations in the characteristic impedance of the signal line 21 can be suppressed.

Note that the embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents that fall within the technical scope of the present invention.

In the above embodiment, a case has been described in which the center CP ₂ of the opening 65 in the lower ground layer 60 is shifted from the center CP ₁ of the opening 55 in the upper ground layer 50 along the +X direction in the figure. , 55 are not particularly limited to this.

For example, the center CP ₂ of the opening 65 may be shifted from the center CP ₁ of the opening 55 along the −X direction in the figure. Alternatively, the center CP ₂ of the opening 65 may be shifted from the center CP ₁ of the opening 55 along the Y direction in the figure. Alternatively, the center CP ₂ of the opening 65 may be shifted from the center CP ₁ of the opening 55 along the X and Y directions in the figure.

In the embodiment described above, all the widths W ₁ to W ₄ of the thin lines 52 and 53 of the upper ground layer 50 and the thin lines 62 and 63 of the lower ground layer 60 are substantially the same, but this is particularly limited. Not done. For example, the width W ₁ of the thin line 52 of the upper ground layer 50 and the width W ₃ of the thin line 62 of the lower ground layer 60 may be different, or the width W ₂ of the thin line 53 of the upper ground layer 50 and the lower ground layer The width W ₄ of the thin lines 63 of 60 may be different. Alternatively, all the widths W ₁ to W ₄ of the thin lines 52 and 53 of the upper ground layer 50 and the thin lines 62 and 63 of the lower ground layer 60 may be different.

Further, in the above-described embodiment, the mesh shape 51 of the upper ground layer 50 and the mesh shape 61 of the lower ground layer 60 have substantially the same shape, but the mesh shape 51 and the mesh shape 61 have substantially the same shape. The relationship is not particularly limited to this. For example, if the center CP ₁ of the opening 55 in the upper ground layer 50 and the center CP ₂ of the opening 65 in the lower ground layer 60 are shifted from each other, the mesh shape 51 of the upper ground layer 50 and the lower ground The mesh shape 61 of the layer 60 may have a different shape.

Further, in the above-described embodiment, the opening 51 of the mesh shape 51 of the upper ground layer 50 has a rectangular shape, but the shape of the opening 51 is not particularly limited to this, and may be, for example, circular, oval, or triangular. , hexagonal, etc. Similarly, in the above-described embodiment, the opening 61 of the mesh shape 61 of the lower ground layer 60 has a rectangular shape, but the shape of the opening 61 is not particularly limited to this, and may be, for example, circular or oval. , triangular, hexagonal, etc.

Regarding the layer structure of the printed wiring board 1, at least one insulating layer is interposed between the signal line 21 and the upper ground layer 50, and at least one insulating layer is interposed between the signal line 21 and the lower ground layer 60. The layer structure is not particularly limited to the above layer structure as long as two insulating layers are interposed.

Further, in the above embodiment, an FPC is illustrated as the printed wiring board 1, but the present invention is not limited to this, and the printed wiring board 1 may be a rigid board.

1... Wiring board 10... Lower base film 11... Top surface 12... Bottom surface 20... Signal layer 21... Signal line 22... Ground line 23... Ground line 30... Contact layer 40... Upper base film 41... Upper surface 42... Lower surface 50... Upper side Ground layer 51...Mesh shape 52, 53...Thin line 54...Intersection 55...Opening CP ₁ ...Center of opening 56...Outer edge line 60...Lower ground layer 61...Mesh shape 62, 63...Thin line 64...Intersection 65...Opening CP ₂ ...Center of opening 66...Outer edge line

Claims (6)

A wiring board having a strip structure,
signal line and
a first ground layer facing the signal line via a first insulating layer;
a second ground layer located on the opposite side of the signal line from the first ground layer and facing the signal line via a second insulating layer;
The first ground layer has a first mesh shape having a plurality of periodically arranged first openings,
The second ground layer has a second mesh shape having a plurality of periodically arranged second openings,
A wiring board in which the center of the first opening and the center of the second opening are shifted from each other in plan view. The wiring board according to claim 1,
the direction in which the first openings are arranged in the first mesh shape and the direction in which the second openings in the second mesh shape are arranged are substantially the same;
A wiring board in which a pitch between the first openings and a pitch between the second openings are substantially the same. The wiring board according to claim 1 or 2,
The first mesh shape is formed by intersecting the first and second thin lines,
The second mesh shape is formed by intersecting third and fourth thin lines,
a crossing angle of the first thin wire with respect to the signal line and a crossing angle of the third thin wire with respect to the signal line are substantially the same;
a crossing angle of the second thin wire with respect to the signal line and a crossing angle of the fourth thin wire with respect to the signal line are substantially the same;
The pitch between the first thin wires and the pitch between the third thin wires are substantially the same,
A wiring board in which the pitch between the second thin wires and the pitch between the fourth thin wires are substantially the same. The wiring board according to claim 3,
The width of the first to fourth thin lines is within a range of ±20% with respect to the average width of the first to fourth thin lines. The wiring board according to any one of claims 2 to 4,
The first ground layer has a first intersection where the first and second thin wires intersect,
The second ground layer has a second intersection where the third and fourth thin lines intersect,
In plan view, the first intersection is located within the second opening such that the first intersection does not overlap the third and fourth thin lines, and
In plan view, the second intersection is located within the first opening so that the second intersection does not overlap with the first and second thin lines,
A wiring board that satisfies the following formula (1).
0.2×P ₀ ≦D ₀ ≦0.8×P ₀ …(1)
However, in the above equation (1),
P ₀ is a pitch along the extending direction of the signal line between the first intersections that are adjacent to each other through the first opening;
D ₀ is the amount of deviation of the second intersection with respect to the first intersection along the extending direction of the signal line. The wiring board according to claim 5,
A wiring board that satisfies the following formula (2).
0.4×P ₀ ≦D ₀ ≦0.6×P ₀ …(2)

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