Printed wiring board

Abstract

To provide a printed-circuit board that can improve signal transmission gain in a waveguide.SOLUTION: A printed-circuit board includes a first insulating layer having a first surface and a second surface opposite to the first surface, a first conductor layer provided on the first surface of the first insulating layer, a second conductor layer provided on the second surface of the first insulating layer and facing the first conductor layer with the first insulating layer in between, and a third conductor layer provided inside the first insulating layer, and the third conductor layer includes a first portion extending in a first direction parallel to the first surface, and a second portion extending in the first direction parallel to the first portion. The first conductor layer and the second conductor layer are provided in a range that overlaps at least a portion of the region sandwiched between the first portion and the second portion when viewed from a plane in a direction perpendicular to the first surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to printed wiring boards. [Background technology]

[0002] Conventionally, there is a technology for forming a waveguide inside a printed wiring board that transmits electromagnetic waves as high-frequency signals. For example, Patent Document 1 discloses a technology in which a plurality of via conductors extending in the thickness direction of a printed wiring board are provided at intervals shorter than the wavelength of the electromagnetic waves to be transmitted, and an area surrounded by the plurality of via conductors functions as a waveguide. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-107518 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the waveguide having the above configuration has a problem in that electromagnetic waves tend to leak from gaps between adjacent via conductors, making it difficult to obtain a transmission gain for signals in the waveguide. [Means for solving the problem]

[0005] A printed wiring board according to one embodiment of the present disclosure includes a first insulating layer having a first surface and a second surface opposite the first surface, a first conductor layer provided on the first surface of the first insulating layer, a second conductor layer provided on the second surface of the first insulating layer and facing the first conductor layer across the first insulating layer, and a third conductor layer provided within the first insulating layer. The third conductor layer has a first portion extending in a first direction parallel to the first surface and a second portion extending in the first direction parallel to the first portion. The first conductor layer and the second conductor layer are provided in a range overlapping at least a portion of a region sandwiched between the first portion and the second portion in a planar perspective view perpendicular to the first surface. The first and second portions of the third conductor layer are spaced apart from the first and second conductor layers in the thickness direction of the first insulating layer, and the distance between the first and third conductor layers and the distance between the second and third conductor layers in the thickness direction is 1 / 20 or less of the wavelength of an electromagnetic wave transmitted through a first waveguide formed by the first, second, and third conductor layers. A printed wiring board according to one embodiment of the present disclosure includes a first insulating layer having a first surface and a second surface opposite the first surface, a first conductor layer provided on the first surface of the first insulating layer, a second conductor layer provided on the second surface of the first insulating layer and facing the first conductor layer across the first insulating layer, and a third conductor layer provided within the first insulating layer. The third conductor layer has a first portion extending in a first direction parallel to the first surface and a second portion extending in the first direction parallel to the first portion. The first conductor layer and the second conductor layer are provided in a range overlapping at least a portion of a region sandwiched between the first portion and the second portion in a planar perspective view perpendicular to the first surface. A plurality of the third conductor layers are provided within the first insulating layer at different positions in the thickness direction of the first insulating layer. The distance in the thickness direction between the first conductor layer and the third conductor layer closest to the first conductor layer, the distance between the second conductor layer and the third conductor layer closest to the second conductor layer, and the distance between adjacent third conductor layers are 1 / 20 or less of the wavelength of the electromagnetic wave transmitted through a first waveguide formed by the first conductor layer, the second conductor layer, and the plurality of third conductor layers. A printed wiring board according to one embodiment of the present disclosure includes a first insulating layer having a first surface and a second surface opposite the first surface, a first conductor layer provided on the first surface of the first insulating layer, a second conductor layer provided on the second surface of the first insulating layer and facing the first conductor layer across the first insulating layer, and a third conductor layer provided within the first insulating layer. The third conductor layer has a first portion extending in a first direction parallel to the first surface and a second portion extending in the first direction parallel to the first portion. The first conductor layer and the second conductor layer are provided in a range overlapping at least a portion of a region sandwiched between the first portion and the second portion in a planar perspective view perpendicular to the first surface. The third conductor layer has a third portion connecting one ends of the first portion and the second portion in the first direction and a fourth portion connecting the other ends of the first portion and the second portion in the first direction, and is continuous in a ring shape in the planar perspective view. A printed wiring board according to one embodiment of the present disclosure includes a first insulating layer having a first surface and a second surface opposite the first surface, a first conductor layer provided on the first surface of the first insulating layer, a second conductor layer provided on the second surface of the first insulating layer and facing the first conductor layer across the first insulating layer, and a third conductor layer provided within the first insulating layer. The third conductor layer has a first portion extending in a first direction parallel to the first surface and a second portion extending in the first direction parallel to the first portion. The first conductor layer and the second conductor layer are provided in a range overlapping at least a portion of a region sandwiched between the first portion and the second portion in a planar perspective view perpendicular to the first surface. A second insulating layer is laminated on the first insulating layer in a range overlapping a portion of the first portion and the second portion, including their ends in the first direction, in the planar perspective view. [Effects of the Invention]

[0006] According to the present disclosure, the transmission gain of a signal in a waveguide can be improved. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a cross-sectional view of a printed wiring board. [Figure 2] 2 is a cross-sectional view of the core layer taken along line AA in FIG. 1. [Figure 3] 2 is a cross-sectional view of the printed wiring board taken along line BB in FIG. 1, viewed from the +Z direction. [Figure 4] 2 is a cross-sectional view of the printed wiring board at the position of the CC line in FIG. 1, viewed from the +Z direction. [Figure 5] 2 is a cross-sectional view of the printed wiring board at the position of the DD line in FIG. 1, viewed from the −Z direction. [Figure 6A] 5A to 5C are cross-sectional views showing a method for manufacturing a core layer. [Figure 6B] 5A to 5C are cross-sectional views showing a method for manufacturing a core layer. [Figure 6C] 5A to 5C are cross-sectional views showing a method for manufacturing a core layer. [Figure 7A]4A to 4C are cross-sectional views showing the method for manufacturing a printed wiring board after manufacturing a core layer. [Figure 7B] 4A to 4C are cross-sectional views showing the method for manufacturing a printed wiring board after manufacturing a core layer. [Figure 7C] 4A to 4C are cross-sectional views showing the method for manufacturing a printed wiring board after manufacturing a core layer. [Figure 7D] 4A to 4C are cross-sectional views showing the method for manufacturing a printed wiring board after manufacturing a core layer. [Figure 7E] 4A to 4C are cross-sectional views showing the method for manufacturing a printed wiring board after manufacturing a core layer. [Figure 8] FIG. 10 is a cross-sectional view of a core layer according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the drawings. However, for the sake of convenience, the drawings referred to below show only the main components necessary for explaining the embodiments in a simplified form. Therefore, the printed wiring board 1 of the present disclosure may include any components not shown in the drawings referred to. Furthermore, the dimensions and dimensional ratios of the components in the drawings do not faithfully represent the dimensions and dimensional ratios of the actual components.

[0009] [Configuration of printed wiring board] The configuration of a printed wiring board 1 according to this embodiment will be described with reference to FIG. In the following, the orientation of each part of printed wiring board 1 will be described using an XYZ Cartesian coordinate system, with the thickness direction of printed wiring board 1 being the Z direction. The extension direction of a first waveguide 4a (described later) provided in printed wiring board 1 is defined as the X direction, and the direction perpendicular to the X and Z directions is defined as the Y direction. Figure 1 is a schematic diagram showing a cross section of printed wiring board 1 perpendicular to the Y direction. Hereinafter, the surface of each layer constituting printed wiring board 1 facing the +Z direction will be referred to as the "top surface," and the surface facing the -Z direction will be referred to as the "bottom surface." The Z direction will also be referred to as the "thickness direction." Viewing printed wiring board 1 from the Z direction, with some components transparent, will be referred to as "planar perspective."

[0010] The printed wiring board 1 is a substrate incorporating an antenna used in millimeter-wave radar or the like, and a transmission line for transmitting signals received by the antenna. The printed wiring board 1 includes a core layer 2, a buildup layer 3a laminated on the upper surface of the core layer 2, a buildup layer 3b laminated on the upper surface of the buildup layer 3a, a buildup layer 3c laminated on the lower surface of the core layer 2, and a buildup layer 3d laminated on the lower surface of the buildup layer 3c. Hereinafter, any one of the buildup layers 3a to 3d will be referred to as a "buildup layer 3." In this embodiment, two buildup layers 3 are laminated on each of the front and back surfaces of the core layer 2.

[0011] The buildup layers 3a to 3d are laminated within a predetermined range from the end of the core layer 2 on the -X direction side and within a predetermined range from the end on the +X direction side, respectively, but are not laminated in the center of the core layer 2 in the X direction. Hereinafter, the portion of the printed wiring board 1 where the buildup layers 3a to 3d are laminated will be referred to as the "rigid portion 1r," and the portion where the buildup layers 3a to 3d are not laminated and the core layer 2 is exposed will be referred to as the "flexible portion 1f." The flexible portion 1f, which is made up only of the core layer 2, is flexible and can be bent. On the other hand, the rigid portion 1r is not flexible because the buildup layers 3a to 3d are laminated on the core layer 2.

[0012] The configuration of the core layer 2 will be described with reference to Figures 1 to 5. Of these, Figure 2 is a cross-sectional view of the core layer 2 taken along line AA in Figure 1. Figure 1 corresponds to the cross-section of the printed wiring board 1 taken along line EE in Figure 2.

[0013] 1 and 2, the core layer 2 includes a first insulating layer 40, a first conductor layer 10 provided on a first surface S1 (see FIG. 2) of the first insulating layer 40, a second conductor layer 20 provided on a second surface S2 (see FIG. 2) opposite the first surface S1 of the first insulating layer 40 and facing the first conductor layer 10 across the first insulating layer 40, a third conductor layer 30 (see FIG. 2) provided inside the first insulating layer 40, and a plurality of via conductors 71 penetrating the first insulating layer 40 in the thickness direction. The first insulating layer 40 is a plate-shaped member parallel to the XY plane. The first surface S1 of the first insulating layer 40 is the upper surface of the first insulating layer 40, and the second surface S2 is the lower surface of the first surface S1. As shown in FIG. 2, the first insulating layer 40 includes an interlayer insulating layer 41 and an interlayer insulating layer 42 stacked on the lower surface of the interlayer insulating layer 41. The third conductor layer 30 is provided inside the first insulating layer 40 at the interface between the interlayer insulating layer 41 and the interlayer insulating layer 42.

[0014] The material of the first insulating layer 40 (the material of the interlayer insulating layer 41 and the interlayer insulating layer 42) is not particularly limited as long as it has insulating properties. Examples of the material of the first insulating layer 40 include organic resins such as polyimide resin, liquid crystal polymer, epoxy resin, bismaleimide-triazine resin, and polyphenylene ether (PPE) resin. Two or more of these organic resins may be mixed together. When an organic resin is used for the first insulating layer 40, a reinforcing material may be blended into the organic resin. Examples of the reinforcing material include glass cloth such as glass fiber and glass nonwoven fabric, aramid cloth such as aramid nonwoven fabric and aramid fiber, and polyester fiber. Two or more of these reinforcing materials may be used in combination. The first insulating layer 40 may also contain an inorganic filler such as silica, barium sulfate, talc, clay, glass, calcium carbonate, or titanium oxide. However, as described below, since the first insulating layer 40 constitutes part of the first waveguide 4a through which electromagnetic waves pass, it is preferable that the first insulating layer 40 be configured without reinforcing materials or fillers to allow electromagnetic waves to pass more efficiently. Among the materials mentioned above, for example, liquid crystal polymer can be used to ensure sufficient flexibility and strength without reinforcing materials or fillers. The thickness of the first insulating layer 40 (the thickness of the interlayer insulating layers 41 and 42) is determined within a range that allows the core layer 2 constituting the flexible portion 1f to have the desired flexibility. For example, the thickness of the interlayer insulating layers 41 and 42 may each be approximately several tens of micrometers.

[0015] In this embodiment, rolled copper foil is used as the first conductor layer 10, the second conductor layer 20, and the third conductor layer 30. This prevents breakage of the first conductor layer 10, the second conductor layer 20, and the third conductor layer 30 when the core layer 2 constituting the flexible portion 1f is bent. The thickness of the rolled copper foil may be, for example, approximately 9 μm to 35 μm.

[0016] FIG. 3 is a cross-section of the printed wiring board 1 taken along line BB in FIG. 1, viewed from the +Z direction. This cross-section corresponds to the cross-section of the printed wiring board 1 taken along the third conductor layer 30. As shown in FIG. 3, the third conductor layer 30 has a ring-shaped shape that is elongated in the X direction in a planar perspective view. The third conductor layer 30 includes a rectangular first portion 31 extending in the X direction (first direction), a rectangular second portion 32 extending in the X direction parallel to the first portion 31, a third portion 33 connecting one end of the first portion 31 and the second portion 32 in the X direction (the ends on the -X direction side), and a fourth portion 34 connecting the other end of the first portion 31 and the second portion 32 in the X direction (the ends on the +X direction side). The second portion 32 is located on the -Y direction side of the first portion 31. The first portion 31, the third portion 33, the second portion 32, and the fourth portion 34 are integrally continuous and form a ring shape in a planar perspective. The first portion 31 and the second portion 32 have overlapping portions when the core layer 2 is viewed in the Y direction. In FIG. 2, the cross-sectional shapes of the first portion 31 and the second portion 32 are configured such that the width of a plane parallel to the first surface S1 (a plane perpendicular to the Z direction) is larger than the width of a plane perpendicular to the Y direction, but this is not limited thereto. The width of the plane perpendicular to the Y direction of the first portion 31 and the second portion 32 may be larger than the width of the plane parallel to the first surface S1 (a plane perpendicular to the Z direction). The first portion 31 and the second portion 32 may be elongated in the thickness direction of the core layer 2.

[0017] From another perspective, the third conductor layer 30 has a shape obtained by removing an elliptical shape (a shape formed by connecting semicircles to both ends of a rectangle, i.e., an oval shape) elongated in the X direction from a substantially rectangular conductor layer elongated in the X direction. In other words, the third conductor layer 30 is formed by providing an elliptical opening 30a (through hole) elongated in the X direction in a substantially rectangular conductor layer elongated in the X direction. The first portion 31 and the second portion 32 are adjacent to the linear portion of the elliptical outer periphery formed by the opening 30a, the third portion 33 is adjacent to one semicircular portion of the elliptical outer periphery formed by the opening 30a, and the fourth portion 34 is adjacent to the other semicircular portion of the elliptical outer periphery formed by the opening 30a. The shape of the opening 30a is not limited to the elliptical shape shown in FIG. 3 . For example, the shapes of both ends may be replaced by semicircles, and may be one of the shapes obtained by dividing an ellipse in half along the major axis or the minor axis. The shape of the opening 30a may also be rectangular (angular).

[0018] In a planar perspective view, the third portion 33 is located within the range of the rigid portion 1r on the −X direction side, and the fourth portion 34 is located within the range of the rigid portion 1r on the +X direction side. Also, in a planar perspective view, the first portion 31 and the second portion 32 extend from within the range of the rigid portion 1r on the −X direction side, through the flexible portion 1f, to within the range of the rigid portion 1r on the +X direction side. Hereinafter, the rectangular region sandwiched between the first portion 31 and the second portion 32 will be referred to as “region R.” Also, the first portion 31 and the second portion 32 are located slightly inward in the Y direction relative to the outer shapes of the third portion 33 and the fourth portion 34. In other words, the edge of the first portion 31 on the +Y direction side is located closer to the −Y direction than the end positions of the third portion 33 and the fourth portion 34 on the +Y direction side. Furthermore, the side of the second portion 32 on the −Y direction side is located on the +Y direction side of the end positions of the third portion 33 and the fourth portion 34 on the −Y direction side.

[0019] FIG. 4 is a cross-section of the printed wiring board at the position of line CC in FIG. 1 as viewed from the +Z direction. As shown in FIG. 4, the first conductor layer 10 is made of a rectangular conductor elongated in the X direction in a planar perspective. The outer shape of the first conductor layer 10 is not limited to a rectangle and may be an ellipse, for example. The first conductor layer 10 is provided in a range overlapping the entire third conductor layer 30 in a planar perspective. Specifically, the width and formation area of ​​the first conductor layer 10 in the Y direction are the same as the width and formation area of ​​the third portion 33 and the fourth portion 34 of the third conductor layer 30 in the Y direction. Furthermore, the width and formation area of ​​the first conductor layer 10 in the X direction are the same as the width and formation area of ​​the third conductor layer 30 in the X direction. Therefore, the first conductor layer 10 is provided in a range overlapping the entire first portion 31, the second portion 32, and the region R in a planar perspective. Circular openings 10a (through holes) are provided in the first conductor layer 10 near the end in the +X direction and near the end in the -X direction. The positions at which the openings 10a are provided are within a range that overlaps with the rigid portion 1r in a planar perspective. The openings 10a function as a connection portion between the first waveguide 4a and the second waveguide 4b, which will be described later. The circle formed by the openings 10a overlaps with the semicircle formed by the end of the opening 30a in the third conductor layer 30 in a planar perspective. Even if the end of the opening 30a is not semicircular, it is preferable that the shape of the openings 10a has a portion that matches the shape of the end of the opening 30a in a planar perspective.

[0020] FIG. 5 is a cross-sectional view of the printed wiring board at the position of line DD in FIG. 1, viewed from the -Z direction. As shown in FIG. 5, the second conductor layer 20 is made of a rectangular conductor elongated in the X direction in a planar perspective. Note that the outer shape of the second conductor layer 20 is not limited to a rectangle and may be an oval, for example. The second conductor layer 20 is provided in a range overlapping the entire third conductor layer 30 in a planar perspective. Specifically, the width and formation area of ​​the second conductor layer 20 in the Y direction are the same as the width and formation area of ​​the third portion 33 and the fourth portion 34 of the third conductor layer 30 in the Y direction. Furthermore, the width and formation area of ​​the second conductor layer 20 in the X direction are the same as the width and formation area of ​​the third conductor layer 30 in the X direction. Therefore, the second conductor layer 20 is provided in a range overlapping the entire first portion 31, the second portion 32, and the region R in a planar perspective.

[0021] 1 , via conductors 71 that penetrate the first insulating layer 40 in the thickness direction (extending in the thickness direction) are provided near the ends of the first conductor layer 10 and the second conductor layer 20 on the −X direction side and near the ends of the first conductor layer 10 and the second conductor layer 20 on the +X direction side. The via conductors 71 are made of conductors that fill via pilot holes that penetrate the first conductor layer 10, the third conductor layer 30, and the first insulating layer 40 to the second conductor layer 20, and electrically connect the first conductor layer 10, the second conductor layer 20, and the third conductor layer 30. The via conductors 71 are formed by applying electrolytic plating to the first insulating layer 40 in which the via pilot holes have been drilled. Therefore, the material of the via conductors 71 may be copper formed by electrolytic plating.

[0022] As shown in Fig. 3, a plurality of via conductors 71 are provided along the semicircle formed by both end portions of the opening 30a of the third conductor layer 30 in a planar perspective view. In the example shown in Fig. 3, seven via conductors 71 are arranged along each of the semicircle formed by one end portion of the opening 30a and the semicircle formed by the other end portion. Note that even if the end portion of the opening 30a is not semicircular, the via conductors 71 are arranged along the shape of the end portion. For example, if the opening 30a is rectangular, a plurality of via conductors 71 are arranged along the sides of the end portions of this rectangle.

[0023] The first conductor layer 10, the second conductor layer 20, the third conductor layer 30, and the plurality of via conductors 71 are electrically connected to a ground conductor (not shown) at ground potential.

[0024] 1 and 2, the first waveguide 4a is formed by the first conductor layer 10, the second conductor layer 20, the third conductor layer 30, and the plurality of via conductors 71 in the core layer 2, and the portion (dielectric) of the first insulating layer 40 that is surrounded by these conductors. The first waveguide 4a extends in the X direction, and transmits electromagnetic waves (high-frequency signals) such as microwaves that are incident through the opening 10a on one side in the X direction, guiding the electromagnetic waves to the opening 10a on the other side.

[0025] In the cross section shown in FIG. 2 , the portion of the first insulating layer 40 through which the electromagnetic waves propagate is a portion sandwiched between the first conductor layer 10 and the second conductor layer 20 in the thickness direction (Z direction) and between the first portion 31 and the second portion 32 of the third conductor layer 30 in the Y direction. Here, the first portion 31 and the second portion 32 of the third conductor layer 30 are spaced apart from the first conductor layer 10 and the second conductor layer 20 in the thickness direction. In this case, the distance d1 between the first conductor layer 10 and the third conductor layer 30 in the thickness direction and the distance d2 between the second conductor layer 20 and the third conductor layer 30 are preferably equal to or less than 1 / 20 of the wavelength λ of the electromagnetic waves transmitted through the first waveguide 4a. By setting the distance d1 and the distance d2 to λ / 20 or less, electromagnetic waves are less likely to leak from the gap between the first conductor layer 10 and the second conductor layer 20 and the gap between the third conductor layer 30 and the second conductor layer 20. This allows the first waveguide 4a to transmit electromagnetic waves with low loss in the direction (X direction) perpendicular to the thickness direction of the printed wiring board 1. Note that even if the distances d1 and d2 are λ / 20 or more, it is possible to ensure a certain level of shielding effectiveness. For example, by setting the distances d1 and d2 to λ / 10 or less, it is possible to ensure a shielding effectiveness of about -30 dB.

[0026] 3, seven via conductors 71 arranged along the edge of the opening 30a of the third conductor layer 30 on the -X direction side define the -X direction end of the first waveguide 4a. Seven via conductors 71 arranged along the edge of the opening 30a on the +X direction side define the +X direction end of the first waveguide 4a. The seven via conductors 71 that form each end of the first waveguide 4a are preferably spaced apart by an interval equal to or less than 1 / 20 of the wavelength λ. This reduces the leakage of electromagnetic waves from the end of the first waveguide 4a. The interval between the via conductors 71 may be equal to or greater than λ / 20 (for example, equal to or less than λ / 10).

[0027] Next, the configuration of the buildup layer 3 will be described. As shown in FIG. 1 , the buildup layer 3a includes an interlayer insulating layer 51 stacked on the upper surface of the core layer 2 and a plurality of via conductors 72 that penetrate the interlayer insulating layer 51 in the thickness direction. The buildup layer 3b includes an interlayer insulating layer 52 stacked on the upper surface of the interlayer insulating layer 51 and a plurality of via conductors 73 that penetrate the interlayer insulating layer 52 in the thickness direction. The interlayer insulating layer 51 and the interlayer insulating layer 52 form a second insulating layer 50. The second insulating layer 50 is stacked on the rigid portion 1r on the −X direction side and the rigid portion 1r on the +X direction side, respectively. The via conductors 72 and 73 are provided in the second insulating layer 50 of the two rigid portions 1r, respectively.

[0028] As shown in the cross-sectional view of Fig. 4, the interlayer insulating layer 51 is provided within the range of the rigid portion 1r in a planar perspective view. The interlayer insulating layer 52 is provided in a range overlapping with the interlayer insulating layer 51 in a planar perspective view. As can be seen by comparing Figs. 3 and 4, the interlayer insulating layer 51 (second insulating layer 50) is laminated in a range overlapping with a portion of the first insulating layer 40, including the ends of the first portion 31 and the second portion 32 of the third conductor layer 30, in a planar perspective view.

[0029] The material of the interlayer insulating layer 51 and the interlayer insulating layer 52 is not particularly limited as long as it has insulating properties. Examples of materials for the interlayer insulating layer 51 and the interlayer insulating layer 52 include organic resins such as epoxy resin, bismaleimide-triazine resin, polyphenylene ether (PPE) resin, polyimide resin, and liquid crystal polymer. Two or more of these organic resins may be mixed together. When an organic resin is used for the interlayer insulating layer 51 and the interlayer insulating layer 52, a reinforcing material may be blended into the organic resin. Examples of reinforcing materials include glass cloth such as glass fiber and glass nonwoven fabric, aramid cloth such as aramid nonwoven fabric and aramid fiber, and polyester fiber. Two or more of these reinforcing materials may be used in combination. The interlayer insulating layer 51 and the interlayer insulating layer 52 may also contain inorganic fillers such as silica, barium sulfate, talc, clay, glass, calcium carbonate, and titanium oxide. The material of interlayer insulating layer 51 and interlayer insulating layer 52 may be the same as or different from the material of first insulating layer 40.

[0030] The via conductors 72 are made of conductors that fill via pilot holes that penetrate the interlayer insulating layer 51. Each of the multiple via conductors 72 is provided at a position that overlaps with the via conductor 71 or the first conductor layer 10 in a planar perspective view, and is in contact with the via conductor 71 or the first conductor layer 10. The via conductors 73 are made of conductors that fill via pilot holes that penetrate the interlayer insulating layer 52. Each of the plurality of via conductors 73 is provided in a position that overlaps with the via conductor 72 in a planar perspective view and is in contact with the via conductor 72. Therefore, the via conductor 72 electrically connects the first conductor layer 10 and the via conductor 73.

[0031] Via conductor 72 is formed by electrolytic plating after a via pilot hole has been drilled in interlayer insulating layer 51. Via conductor 73 is formed by electrolytic plating after a via pilot hole has been drilled in interlayer insulating layer 52. Therefore, the material of via conductor 72 and via conductor 73 may be copper formed by electrolytic plating. Via conductor 72 and via conductor 73 are electrically connected to a ground conductor (not shown) at a ground potential.

[0032] In a planar perspective, the plurality of via conductors 72 and the plurality of via conductors 73 are arranged at equal intervals so as to surround the circular opening 10a of the first conductor layer 10. More specifically, in a planar perspective, a via conductor 72 and a via conductor 73 are provided at each of the positions where the plurality of via conductors 71 shown in Fig. 4 are formed, and the via conductors 72 and 73 are also provided at the positions indicated by dashed lines in Fig. 4. The via conductor 72 provided at the position where the via conductor 71 is formed is electrically connected to the first conductor layer 10 via the via conductor 71. Furthermore, the via conductor 72 provided at the position indicated by dashed lines in Fig. 4 is in contact with the first conductor layer 10.

[0033] As shown in FIG. 1 , the multiple via conductors 72 and the multiple via conductors 73 form a second waveguide 4b extending in the thickness direction. The second waveguide 4b is provided in each of the rigid portions 1r on the −X direction side and the +X direction side. Each second waveguide 4b is connected to the first waveguide 4a through an opening 10a in the first conductor layer 10. Therefore, as shown in FIG. 1 , the electromagnetic wave W incident from the second waveguide 4b of the rigid portion 1r on the +X direction side travels through the second waveguide 4b in the −Z direction before entering the first waveguide 4a, traveling through the first waveguide 4a in the −X direction, and then entering the second waveguide 4b of the rigid portion 1r on the −X direction side. The electromagnetic wave W then travels through the second waveguide 4b in the +Z direction and is guided to the upper surface of the second insulating layer 50. Here, it is preferable that the organic resin constituting first insulating layer 40 exhibits a lower dielectric constant than the organic resin constituting interlayer insulating layer 51 and interlayer insulating layer 52. This is because the waveguide (first waveguide 4a) formed in first insulating layer 40 is longer in distance than the waveguide (second waveguide 4b) formed in interlayer insulating layer 51 and interlayer insulating layer 52, and therefore an organic resin with a lower relative dielectric constant can reduce transmission loss.

[0034] The spacing between adjacent via conductors 72 constituting the second waveguide 4b is preferably 1 / 20 of the above-mentioned wavelength λ or less. Similarly, the spacing between adjacent via conductors 73 constituting the second waveguide 4b is preferably 1 / 20 of the above-mentioned wavelength λ or less. This reduces leakage of electromagnetic waves from the second waveguide 4b. The spacing between adjacent via conductors 72 and the spacing between adjacent via conductors 73 may be λ / 20 or more (for example, λ / 10 or less).

[0035] The buildup layer 3c includes an interlayer insulating layer 61 laminated on the lower surface of the core layer 2, and a wiring conductor 74 provided on the lower surface of the interlayer insulating layer 61. The buildup layer 3d includes an interlayer insulating layer 62 laminated on the lower surface of the interlayer insulating layer 61, a via conductor 75 penetrating the interlayer insulating layer 62 in the thickness direction, and a wiring conductor 76 provided on the lower surface of the interlayer insulating layer 62. Of these, the interlayer insulating layer 61 and the interlayer insulating layer 62 form a second insulating layer 60. The second insulating layer 60 is laminated on the rigid portion 1r on the -X direction side and the rigid portion 1r on the +X direction side, respectively.

[0036] As shown in the cross-sectional view of Fig. 5, interlayer insulating layer 61 is provided within the range of rigid portion 1r in a planar perspective. Interlayer insulating layer 62 is provided in a range overlapping with interlayer insulating layer 61 in a planar perspective. As can be seen by comparing Figs. 3 and 5, interlayer insulating layer 61 (second insulating layer 60) is laminated in a range overlapping with a portion of first insulating layer 40, including ends of first portion 31 and second portion 32 of third conductor layer 30, in a planar perspective. The material of interlayer insulating layer 61 and interlayer insulating layer 62 may be the same as the material of interlayer insulating layer 51 and interlayer insulating layer 52.

[0037] The wiring conductors 74 and 76 are wirings formed into a desired pattern. The material of the wiring conductors 74 and 76 is not particularly limited as long as it is conductive, but may be, for example, rolled copper foil and / or copper formed by electrolytic plating.

[0038] The via conductor 75 is made of a conductor filling a via pilot hole that penetrates the interlayer insulating layer 62, and electrically connects the wiring conductor 74 and the wiring conductor 76. The via conductor 75 is formed by performing electrolytic plating on a via pilot hole that has been drilled in the interlayer insulating layer 62. Therefore, the material of the via conductor 75 may be copper formed by electrolytic plating.

[0039] In addition, a via conductor may be provided in the interlayer insulating layer 61 of the build-up layer 3c, and a wiring conductor (not shown) provided on the underside of the core layer 2 may be electrically connected to the wiring conductor 74 through this via conductor. Furthermore, wiring conductors (not shown) may be provided in buildup layers 3a and 3b, and via conductors for electrically connecting these wiring conductors to wiring conductors, etc., in other layers may be provided in interlayer insulating layers 51 and 52. Furthermore, printed wiring board 1 may be provided with through-hole conductors (not shown) that penetrate in the thickness direction, and these through-hole conductors may electrically connect wiring conductors, etc., provided in two or more different layers.

[0040] [Method for manufacturing printed wiring board] Next, a method for manufacturing printed wiring board 1 will be described. First, a method for manufacturing core layer 2 will be described with reference to FIGS. 6A to 6C, and then a method for manufacturing printed wiring board 1 by laminating buildup layer 3 on core layer 2 will be described with reference to FIGS. 7A to 7E.

[0041] In the manufacturing process of the core layer 2, first, as shown in Figure 6A, a flexible substrate is prepared in which rolled copper foil 101, which will become the first conductor layer 10, is provided over the entire upper surface of the interlayer insulating layer 41, and rolled copper foil 301, which will become the third conductor layer 30, is provided over the entire lower surface of the interlayer insulating layer 41.

[0042] Next, as shown in FIG. 6B, the rolled copper foil 301 is patterned by a known patterning method to form the third conductor layer 30 having the first portion 31, the second portion 32, the third portion 33, and the fourth portion 34 shown in FIG. 3.

[0043] Next, a semi-cured resin material and rolled copper foil 201 are laid up from the -Z direction side on the surface on which the third conductor layer 30 is formed, and pressure and heat are applied in the Z direction to melt the resin and then harden it. This results in a flexible substrate in which the third conductor layer 30 is formed inside the first insulating layer 40, as shown in FIG. 6C. The flexible substrate in FIG. 6C has the rolled copper foil 101 that will become the first conductor layer 10 provided over the entire upper surface, and the rolled copper foil 201 that will become the second conductor layer 20 provided over the entire lower surface. The rolled copper foil 101 and the rolled copper foil 201 of this flexible substrate are patterned using a known patterning method, thereby completing the core layer 2 shown in FIGS. 2 and 7A.

[0044] 7B, via conductors 71 are formed in the core layer 2. Specifically, first, via pilot holes penetrating the first conductor layer 10, the third conductor layer 30, and the first insulating layer 40 are formed by laser processing, drilling, or the like from the +Z direction side at the formation positions of the via conductors 71. Thereafter, copper via conductors 71 are formed by a combination of electrolytic panel plating and a subtractive method, or by a method such as a modified semi-additive process (MSAP).

[0045] Next, as shown in FIG. 7C , interlayer insulating layer 51 is formed on the upper surface of core layer 2, and interlayer insulating layer 61 is formed on the lower surface. Specifically, a prepreg and copper foil (not shown) that will become interlayer insulating layer 51 are laid up on the upper surface of core layer 2, and a prepreg and copper foil (not shown) that will become interlayer insulating layer 61 are laid up on the lower surface of core layer 2. Here, the prepreg is a member made by impregnating a reinforcing material such as glass cloth with a resin and semi-curing it. Thereafter, the obtained laminate is pressed in the Z direction and heated to melt the prepreg and then harden it, thereby obtaining interlayer insulating layer 51 and interlayer insulating layer 61.

[0046] Next, as shown in FIG. 7D , via conductors 72 are formed in interlayer insulating layer 51, and wiring conductors 74 are formed on the underside of interlayer insulating layer 61. Specifically, first, via pilot holes that penetrate interlayer insulating layer 51 are formed from the +Z direction side at the positions where via conductors 72 are to be formed by laser processing, drilling, or the like. Thereafter, a copper plating layer that becomes via conductors 72 and wiring conductors 74 is formed by electrolytic panel plating, and portions of the plating layer are removed by a subtractive method to form via conductors 72 and wiring conductors 74. Alternatively, via conductors 72 and wiring conductors 74 may be selectively formed by MSAP. This completes buildup layers 3a and 3c.

[0047] 7E, interlayer insulating layer 52 is formed on the upper surface of buildup layer 3a, and interlayer insulating layer 62 is formed on the lower surface of buildup layer 3c, using a method similar to that used to form interlayer insulating layer 51 and interlayer insulating layer 61. Furthermore, via conductor 73 is formed in interlayer insulating layer 52, and via conductor 75 and wiring conductor 76 are formed in interlayer insulating layer 62, using a method similar to that used to form via conductor 72 and wiring conductor 74.

[0048] Finally, the portions of the buildup layers 3a to 3d in the laminate shown in Fig. 7E that overlap with the flexible section 1f in a planar perspective are removed to complete the printed wiring board 1 shown in Fig. 1. One method for removing the buildup layers 3a to 3d that overlap with the flexible section 1f is to form a laser blocking layer (not shown) (such as a plated coverlay film) on the surface of the core layer 2 in advance, and then remove only the buildup layers 3a to 3d by laser processing while protecting the core layer 2 of the flexible section 1f with the laser blocking layer. Alternatively, when forming the build-up layer 3 in Figures 7C to 7E, the portion of the prepreg that overlaps with the flexible portion 1f may be removed, and then pressure and heat may be applied to selectively form the build-up layer 3 on the rigid portion 1r excluding the flexible portion 1f.

[0049] [Modification] Next, a modification of the above embodiment will be described. In the above embodiment, a configuration in which one third conductor layer 30 is provided on the core layer 2 is exemplified, but instead, multiple (two or more) third conductor layers 30 may be provided at different positions in the thickness direction of the first insulating layer 40.

[0050] FIG. 8 is a cross-sectional view showing a core layer 2 in which two third conductor layers 30 are provided. The core layer 2 shown in FIG. 8 has three interlayer insulating layers 41 to 43 stacked in order in the Z direction, and a third conductor layer 30 is formed on each of the upper and lower surfaces of the central interlayer insulating layer 42. A first conductor layer 10 is formed on the upper surface of the interlayer insulating layer 41, and a second conductor layer 20 is formed on the lower surface of the interlayer insulating layer 43. The shapes of the two third conductor layers 30 in a planar perspective are the same as the shapes of the third conductor layers 30 in the above embodiment shown in FIG. 3. The two third conductor layers 30 are provided at positions where they overlap in a planar perspective. The shapes of the first conductor layer 10 and the second conductor layer 20 in a planar perspective are the same as those in the above embodiment. In this modification, the first conductor layer 10, the second conductor layer 20, the two third conductor layers 30, and the multiple via conductors 71 in the core layer 2, and the portions (dielectrics) of the first insulating layer 40 surrounded by these conductors form a first waveguide 4a.

[0051] The distance in the thickness direction between the first conductor layer 10 and the third conductor layer 30 closest to the first conductor layer 10 (i.e., the third conductor layer 30 on the +Z direction side) is defined as d1. The distance between the second conductor layer 20 and the third conductor layer 30 closest to the second conductor layer 20 (i.e., the third conductor layer 30 on the −Z direction side) is defined as d2. The distance between adjacent third conductor layers 30 is defined as d3. In this modification, the distances d1, d2, and d3 are preferably each equal to or less than 1 / 20 of the wavelength λ of the electromagnetic wave transmitted through the first waveguide 4a. The distances d1 to d3 may be uniform or may be different from one another. By setting the distances d1 to d3 to λ / 20 or less, electromagnetic waves are less likely to leak from the gaps between the first conductor layer 10 and the third conductor layer 30, the gaps between the second conductor layer 20 and the third conductor layer 30, and the gaps between the third conductor layers 30. This allows the first waveguide 4a to transmit electromagnetic waves in the X direction with low loss. Note that even if the intervals d1 to d3 are λ / 20 or more, it is possible to ensure a certain level of shielding effectiveness. For example, by setting the intervals d1 to d3 to λ / 10 or less, it is possible to ensure an average shielding effectiveness of about -30 dB. The core layer 2 may be provided with three or more third conductor layers 30.

[0052] 〔effect〕 As described above, the printed wiring board 1 according to this embodiment includes a first insulating layer 40, a first conductor layer 10 provided on a first surface S1 of the first insulating layer 40, a second conductor layer 20 provided on a second surface S2 of the first insulating layer 40 opposite the first surface S1 and facing the first conductor layer 10 across the first insulating layer 40, and a third conductor layer 30 provided inside the first insulating layer 40. The third conductor layer 30 has a first portion 31 extending in an X direction (first direction) parallel to the first surface S1, and a second portion 32 extending in the X direction parallel to the first portion 31. The first conductor layer 10 and the second conductor layer 20 are provided in a range overlapping at least a portion of a region R sandwiched between the first portion 31 and the second portion 32 in a planar perspective view from the Z direction perpendicular to the first surface S1. This makes it possible to provide first waveguide 4a, which can transmit electromagnetic waves in a direction (X direction) parallel to first surface S1 of first insulating layer 40, inside printed wiring board 1. Furthermore, first portion 31 and second portion 32, which constitute part of first waveguide 4a, extend in the X direction parallel to first surface S1 of first insulating layer 40, thereby reducing leakage of electromagnetic waves in the extension direction of first insulating layer 40. This makes it possible to improve the transmission gain of signals in first waveguide 4a.

[0053] Furthermore, the first conductor layer 10 and the second conductor layer 20 are provided in a range that overlaps at least the entire region R sandwiched between the first portion 31 and the second portion 32 in a planar perspective view. This makes it possible to further reduce leakage of electromagnetic waves from the first waveguide 4a, thereby further improving the transmission gain of signals in the first waveguide 4a.

[0054] Furthermore, the first conductor layer 10 and the second conductor layer 20 are provided in an area that overlaps at least the first portion 31 and the second portion 32 in a planar perspective view. This makes it possible to further reduce leakage of electromagnetic waves from the first waveguide 4a, thereby further improving the transmission gain of signals in the first waveguide 4a.

[0055] Furthermore, the first portion 31 and the second portion 32 of the third conductor layer 30 are spaced apart from the first conductor layer 10 and the second conductor layer 20 in the thickness direction of the first insulating layer 40. This allows the first waveguide 4a to be configured without providing a conductor extending in the thickness direction to electrically connect the first conductor layer 10 and the second conductor layer 20 to the first portion 31 and the second portion 32. Therefore, the first waveguide 4a can be provided inside the printed wiring board 1 with a simple configuration.

[0056] Furthermore, the distance d1 between the first conductor layer 10 and the third conductor layer 30 and the distance d2 between the second conductor layer 20 and the third conductor layer 30 in the thickness direction are equal to or less than 1 / 20 of the wavelength λ of the electromagnetic wave transmitted through the first waveguide 4a formed by the first conductor layer 10, the second conductor layer 20, and the third conductor layer 30. This makes it possible to reduce leakage of the electromagnetic wave from the gap between the first conductor layer 10 and the third conductor layer 30 and the gap between the second conductor layer 20 and the third conductor layer 30. Therefore, the electromagnetic wave can be transmitted through the first waveguide 4a with low loss.

[0057] Furthermore, in printed wiring board 1 according to the above-described modification, a plurality of third conductor layers 30 are provided inside first insulating layer 40, the third conductor layers 30 being provided at different positions in the thickness direction of first insulating layer 40. By changing the number of third conductor layers 30 in this way, the width of first waveguide 4a in the thickness direction can be easily adjusted.

[0058] In the above modification, the distance d1 in the thickness direction between the first conductor layer 10 and the third conductor layer 30 closest to the first conductor layer 10, the distance d2 between the second conductor layer 20 and the third conductor layer 30 closest to the second conductor layer 20, and the distance d3 between adjacent third conductor layers 30 are preferably equal to or less than 1 / 20 of the wavelength λ of the electromagnetic wave transmitted through the first waveguide 4a formed by the first conductor layer 10, the second conductor layer 20, and the plurality of third conductor layers 30. This reduces leakage of electromagnetic waves from gaps between the first conductor layer 10 and the third conductor layer 30, gaps between the second conductor layer 20 and the third conductor layer 30, and gaps between the third conductor layers 30. Therefore, even in a configuration in which a plurality of third conductor layers 30 are provided, electromagnetic waves can be transmitted with low loss through the first waveguide 4a.

[0059] The third conductor layer 30 has a third portion 33 connecting one ends of the first portion 31 and the second portion 32 in the X direction and a fourth portion 34 connecting the other ends thereof, and these are continuous in a ring shape in a planar perspective. This further reduces leakage of electromagnetic waves in the extension direction of the first insulating layer 40. This further improves the signal transmission gain in the first waveguide 4a.

[0060] The first insulating layer 40 further includes a second insulating layer 50 laminated in a range that overlaps with a portion of the first portion 31 and the second portion 32, including their ends in the X direction, in a planar perspective view. This allows the portion where the second insulating layer 50 is provided to be a rigid portion 1r that does not have flexibility, and the portion where the second insulating layer 50 is not provided to be a flexible portion 1f. This allows a printed wiring board 1 having a rigid portion 1r and a flexible portion 1f to be realized. The second insulating layer 50 is located at both ends of the first portion 31 and the second portion 32 in the X direction. The second insulating layer 50 is located between and spaced apart from both ends of the first portion 31 and the second portion 32 in the X direction. Nothing equivalent to the second insulating layer 50 exists between the two second insulating layers 50 located between and spaced apart from both ends of the first portion 31 and the second portion 32 in the X direction. Even in areas on the first insulating layer 40 where the second insulating layer 50 is not provided, a protective film may be provided to protect the first portion 31, the second portion 32 and the second conductor layer 20 to an extent that does not impair the flexibility of the flexible portion 1f.

[0061] The second insulating layer 50 is provided with a plurality of via conductors 72 and a plurality of via conductors 73 extending in the thickness direction of the second insulating layer 50. The plurality of via conductors 72 and a plurality of via conductors 73 are arranged to form a second waveguide 4b extending in the thickness direction. The second waveguide 4b is connected to a first waveguide 4a formed by the first conductor layer 10, the second conductor layer 20, and the third conductor layer 30. With this configuration, the first waveguide 4a can transmit electromagnetic waves in the extension direction (X direction) of the printed wiring board 1 (flexible portion 1f), while the second waveguide 4b can transmit electromagnetic waves in the thickness direction of the printed wiring board 1. Therefore, a three-dimensional electromagnetic wave transmission path can be provided in the printed wiring board 1.

[0062] Furthermore, the portion that does not overlap with the second insulating layer 50 in a plan view is flexible. With this configuration, printed wiring board 1 can be obtained in which the flexible portion 1f is capable of transmitting electromagnetic waves through first waveguide 4a. Therefore, even when flexible portion 1f is bent, electromagnetic waves can be transmitted in the extending direction of flexible portion 1f.

[0063] Furthermore, the first conductor layer 10, the second conductor layer 20, and the third conductor layer 30 are made of rolled copper foil. This makes it difficult for the first conductor layer 10, the second conductor layer 20, and the third conductor layer 30 to break even if the flexible portion 1f is repeatedly bent. Therefore, the first waveguide 4a, which has high durability, can be provided inside the printed wiring board 1.

[0064] The first conductor layer 10, the second conductor layer 20, and the third conductor layer 30 are set to a ground potential, which allows the first waveguide 4a having the first conductor layer 10, the second conductor layer 20, and the third conductor layer 30 to transmit electromagnetic waves stably.

[0065] 〔others〕 The above embodiment is merely an example, and various modifications are possible. For example, in the above embodiment, a configuration has been illustrated in which the first conductor layer 10 and the second conductor layer 20 overlap the entire region R (a rectangular region sandwiched between the first portion 31 and the second portion 32) shown in Fig. 3 and also overlap the first portion 31 and the second portion 32 in a planar perspective view, but this is not limiting. For example, the first conductor layer 10 and the second conductor layer 20 may be provided in a range that overlaps the region R in a planar perspective view but does not overlap the first portion 31 and the second portion 32. Alternatively, the first conductor layer 10 and the second conductor layer 20 may be provided in a range that does not overlap the first portion 31 and the second portion 32 in a planar perspective view but overlaps with a portion of the region R. Even with these configurations, signals can be transmitted through the first waveguide 4a as long as the gaps between the first conductor layer 10 and the first and second portions 31 and 32 of the third conductor layer 30, and the gaps between the second conductor layer 20 and the first and second portions 31 and 32 of the third conductor layer 30 are large enough to prevent electromagnetic waves from leaking (preferably λ / 20 or less).

[0066] The first conductor layer 10 may be provided (solidly) on the entire first surface S1 of the first insulating layer 40. The second conductor layer 20 may be provided (solidly) on the entire second surface S2 of the first insulating layer 40.

[0067] Furthermore, the third conductor layer 30 does not have to be continuous in an annular shape, and may be partially interrupted within a range where a signal can be transmitted by the first waveguide 4a. Thus, the third conductor layer 30 may be made up of a plurality of parts that are separated from each other.

[0068] Although the configuration in which a portion of the portion of printed wiring board 1 where first waveguide 4a is provided (flexible portion 1f in the above embodiment) is flexible has been exemplified, the present invention is not limited to this, and the entire printed wiring board 1 may be inflexible. In this case, since first conductor layer 10, second conductor layer 20, and third conductor layer 30 do not necessarily need to be resistant to bending, rolled copper foil does not necessarily have to be used, and copper formed by electrolytic plating, for example, may be used.

[0069] Furthermore, the printed wiring board 1 is only required to have at least the first waveguide 4a, which is configured by the first conductor layer 10, the second conductor layer 20, and the third conductor layer 30, and the transmission path of the electromagnetic waves other than the first waveguide 4a is not particularly limited. For example, a microstrip line or a coplanar line may be included. Furthermore, the second waveguide 4b may be omitted.

[0070] Furthermore, although the above example shows a configuration in which two buildup layers 3 are laminated on each of the upper and lower surfaces of the core layer 2, the present invention is not limited to this. One or three or more buildup layers 3 may be laminated on the upper surface of the core layer 2, and one or three or more buildup layers 3 may be laminated on the lower surface of the core layer 2. Alternatively, the present invention may have a configuration in which a buildup layer 3 is laminated on only one of the upper and lower surfaces of the core layer 2.

[0071] In addition, the specific details of the configuration, structure, positional relationship, shape, etc. shown in the above embodiment can be appropriately changed without departing from the spirit of the present disclosure. Furthermore, the configuration, structure, positional relationship, and shape shown in the above embodiment can be appropriately combined without departing from the spirit of the present disclosure. [Explanation of symbols]

[0072] 1 Printed wiring board 1F Flexible section 1r Rigid part 2 Core layer 3, 3a~3d Build-up layer 4a 1st waveguide 4b 2nd waveguide 10 First conductor layer 10a opening 101 Rolled copper foil 20 Second conductor layer 201 Rolled copper foil 30 Third conductor layer 30a opening 31 Part 1 32 Part 2 33 Part 3 34 Part 4 301 rolled copper foil 40 First insulating layer 40 41~43, 51, 52, 61, 62 Interlayer insulating layer 50, 60 Second insulating layer 71 Via conductor 71~73, 75 Via conductor 74, 76 Wiring conductor R region W electromagnetic waves

Claims

1. a first insulating layer having a first surface and a second surface opposite the first surface; a first conductor layer provided on the first surface of the first insulating layer; a second conductor layer provided on the second surface of the first insulating layer and facing the first conductor layer across the first insulating layer; a third conductor layer provided inside the first insulating layer; Equipped with the third conductor layer has a first portion extending in a first direction parallel to the first surface and a second portion extending in the first direction parallel to the first portion, the first conductor layer and the second conductor layer are provided in a range overlapping with at least a part of a region sandwiched between the first portion and the second portion in a planar perspective view from a direction perpendicular to the first surface, the first portion and the second portion of the third conductor layer are spaced apart from the first conductor layer and the second conductor layer in a thickness direction of the first insulating layer, a distance between the first conductor layer and the third conductor layer and a distance between the second conductor layer and the third conductor layer in the thickness direction are equal to or less than 1 / 20 of a wavelength of an electromagnetic wave transmitted through a first waveguide constituted by the first conductor layer, the second conductor layer, and the third conductor layer; Printed wiring board.

2. A first insulating layer having a first surface and a second surface opposite the first surface; a first conductor layer provided on the first surface of the first insulating layer; a second conductor layer provided on the second surface of the first insulating layer and facing the first conductor layer across the first insulating layer; a third conductor layer provided inside the first insulating layer; Equipped with the third conductor layer has a first portion extending in a first direction parallel to the first surface and a second portion extending in the first direction parallel to the first portion, the first conductor layer and the second conductor layer are provided in a range overlapping with at least a part of a region sandwiched between the first portion and the second portion in a planar perspective view from a direction perpendicular to the first surface, a plurality of the third conductor layers are provided inside the first insulating layer at different positions in a thickness direction of the first insulating layer, a distance in the thickness direction between the first conductor layer and the third conductor layer closest to the first conductor layer, a distance between the second conductor layer and the third conductor layer closest to the second conductor layer, and a distance between adjacent third conductor layers are 1 / 20 or less of a wavelength of an electromagnetic wave transmitted through a first waveguide constituted by the first conductor layer, the second conductor layer, and the plurality of third conductor layers; Printed wiring board.

3. A first insulating layer having a first surface and a second surface opposite the first surface; a first conductor layer provided on the first surface of the first insulating layer; a second conductor layer provided on the second surface of the first insulating layer and facing the first conductor layer across the first insulating layer; a third conductor layer provided inside the first insulating layer; Equipped with the third conductor layer has a first portion extending in a first direction parallel to the first surface and a second portion extending in the first direction parallel to the first portion, the first conductor layer and the second conductor layer are provided in a range overlapping with at least a part of a region sandwiched between the first portion and the second portion in a planar perspective view from a direction perpendicular to the first surface, the third conductor layer has a third portion connecting one ends of the first portion and the second portion in the first direction and a fourth portion connecting the other ends of the first portion and the second portion in the first direction, and is continuous in an annular shape in the planar perspective; Printed wiring board.

4. A first insulating layer having a first surface and a second surface opposite the first surface; a first conductor layer provided on the first surface of the first insulating layer; a second conductor layer provided on the second surface of the first insulating layer and facing the first conductor layer across the first insulating layer; a third conductor layer provided inside the first insulating layer; Equipped with the third conductor layer has a first portion extending in a first direction parallel to the first surface and a second portion extending in the first direction parallel to the first portion, the first conductor layer and the second conductor layer are provided in a range overlapping with at least a part of a region sandwiched between the first portion and the second portion in a planar perspective view from a direction perpendicular to the first surface, a second insulating layer laminated in a range overlapping with a part of the first insulating layer, the part including the end portions of the first portion and the second portion in the first direction, in the planar perspective view; Printed wiring board.

5. the first conductor layer and the second conductor layer are provided in a range overlapping at least the entire region sandwiched between the first portion and the second portion in the planar perspective view; The printed wiring board according to claim 1 .

6. the first conductor layer and the second conductor layer are provided in an area overlapping at least the first portion and the second portion in the planar perspective view; The printed wiring board according to claim 5 .

7. a plurality of the third conductor layers are provided inside the first insulating layer at different positions in a thickness direction of the first insulating layer; The printed wiring board according to claim 1, 5 or 6.

8. a distance in the thickness direction between the first conductor layer and the third conductor layer closest to the first conductor layer, a distance between the second conductor layer and the third conductor layer closest to the second conductor layer, and a distance between adjacent third conductor layers are 1 / 20 or less of a wavelength of an electromagnetic wave transmitted through a first waveguide constituted by the first conductor layer, the second conductor layer, and the plurality of third conductor layers; The printed wiring board according to claim 7.

9. the third conductor layer has a third portion connecting one ends of the first portion and the second portion in the first direction and a fourth portion connecting the other ends of the first portion and the second portion in the first direction, and is continuous in an annular shape in the planar perspective; The printed wiring board according to any one of claims 1 and 5 to 8.

10. a second insulating layer laminated in a range overlapping with a part of the first insulating layer, the part including the end portions of the first portion and the second portion in the first direction, in the planar perspective view; The printed wiring board according to any one of claims 1 and 5 to 9.

11. the second insulating layer is provided with a plurality of via conductors extending in a thickness direction of the second insulating layer, the first conductor layer, the second conductor layer, and the third conductor layer constitute a first waveguide; the plurality of via conductors are arranged to form a second waveguide extending in the thickness direction, The second waveguide is connected to the first waveguide. The printed wiring board according to claim 4 or 10.

12. The printed wiring board according to claim 4 , wherein a portion of the printed wiring board that does not overlap with the second insulating layer in the plan view is flexible.

13. the first conductor layer, the second conductor layer, and the third conductor layer are made of rolled copper foil; The printed wiring board according to any one of claims 1 to 12.

14. the first conductor layer, the second conductor layer, and the third conductor layer are at ground potential; The printed wiring board according to any one of claims 1 to 13.

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