Wiring board, low dielectric constant structure, and method for manufacturing a wiring board

Abstract

[Problem] To provide: a circuit board which exhibits excellent transmission characteristics while suppressing any impact on other properties thereof; a low-dielectric structure; and a method for producing a circuit board. [Solution] A circuit board according to the present technology is equipped with a substrate layer and a signal line. The substrate layer comprises a dielectric material, and has a first main surface and a second main surface on the side thereof opposite the first main surface. The signal line comprises a metal, and is provided on the first main surface. A groove having a prescribed depth from the first main surface is provided in the substrate layer on both sides of the signal line when viewed from a direction perpendicular to the first main surface.

Description

Technical Field

[0001] The present technology relates to a wiring board suitable for transmission of high-frequency signals, a low dielectric constant structure, and a method for manufacturing a wiring board.

Background Art

[0002] In recent years, with the explosive increase in the amount of information processing in electronic devices, a large number of digital signal standards exceeding 1 Gbps have been proposed and installed in various electronic devices. In the future, from the perspective of the spread of 5G (the fifth-generation mobile communication system), the handling of further high-frequency signals will become important. In an electronic device, in order to establish a stable high-frequency signal (high-speed signal transmission), it is very important that the signal energy is not lost as much as possible in the substrate through which the high-frequency signal is transmitted. This is because the less the loss of signal energy in the substrate, the longer the distance the signal can be transmitted with less energy.

[0003] In flexible printed boards and rigid boards, one of the factors causing signal energy loss is the dielectric loss of the base material constituting each board. Dielectric loss is expressed by a physical quantity called dielectric tangent, and the larger the dielectric tangent, the larger the dielectric loss. Generally, an RF-4 (Flame Retardant Type 4) material is mainly used for rigid boards, and a polyimide material is mainly used for flexible printed boards. Recently, for the purpose of high-speed signal transmission, LCP (Liquid Crystal Polymer) materials and fluorine-based materials with a smaller dielectric tangent have also begun to be utilized.

[0004] In order to reduce the dielectric tangent of the base material in the substrate, reducing the ratio of the dielectric material in the base material layer (low dielectric constant structuring) is also one of the means. Specifically, considering that the relative dielectric constant of air is 1.0 and the dielectric tangent is almost zero, a technique of providing air bubbles in the base material has also been proposed (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2015-199845 [Patent Document 2] International Publication No. 2015 / 182696 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, as described in Patent Documents 1 and 2, when air bubbles are introduced into the substrate, not only transmission characteristics but also bending stress, fracture strength, and moisture absorption characteristics are affected, which presents a problem in that the range of material selection for product design becomes very narrow.

[0007] In light of the above circumstances, the objective of this technology is to provide a wiring board, a low dielectric constant structure, and a method for manufacturing a wiring board that have excellent transmission characteristics and suppress the influence on other characteristics. [Means for solving the problem]

[0008] To achieve the above objective, the wiring board relating to this technology comprises a base layer and signal lines. The above-mentioned substrate layer is made of a dielectric material and has a first main surface and a second main surface opposite to the first main surface. The above signal line is made of metal and is provided on the first main surface. The substrate layer is provided with grooves on both sides of the signal line, having a predetermined depth from the first main surface when viewed from a direction perpendicular to the first main surface.

[0009] The substrate layer may be made of the dielectric material and may have a support portion provided between the grooves, between the signal line and the second main surface, to support the signal line.

[0010] The above-mentioned support portion may include a plurality of columnar parts spaced apart from each other.

[0011] The columnar portion may be inclined with respect to the thickness direction of the base material layer.

[0012] The columnar portion described above may have holes.

[0013] The above signal lines include high-speed signal lines for transmitting high-frequency signals and low-speed signal lines for transmitting low-frequency signals. The grooves described above are provided on both sides of the high-speed signal line when viewed from the above direction, but do not necessarily have to be provided on both sides of the front low-speed signal line when viewed from the above direction.

[0014] The dielectric material mentioned above is carbon dioxide polyimide.

[0015] To achieve the above objective, the low dielectric constant structure relating to this technology comprises a substrate layer and a transmission line. The above-mentioned substrate layer is made of a dielectric material and has a first main surface and a second main surface opposite to the first main surface. The above-mentioned transmission line is provided on the first main surface. The substrate layer is provided with grooves on both sides of the transmission path, having a predetermined depth from the first main surface when viewed from a direction perpendicular to the first main surface.

[0016] To achieve the above objective, the manufacturing method of a low dielectric constant structure according to this technology forms a substrate layer made of a dielectric material, having a first main surface and a second main surface opposite to the first main surface, with grooves having a predetermined depth extending from the first main surface. A signal line made of metal is formed on the first main surface, and a structure is formed in which grooves are provided on both sides of the signal line when viewed from a direction perpendicular to the first main surface.

[0017] In the process of forming the above-mentioned base material layer, the grooves may be formed by a removal process that removes the constituent material of the base material layer by laser irradiation.

[0018] The above laser may be a pulsed laser.

[0019] The above pulse laser may be an ultrashort pulse laser.

[0020] In the step of forming the base material layer, the base material layer may be formed by an additive process of laminating the constituent materials of the base material layer.

Brief Description of the Drawings

[0021] [Figure 1] It is a cross-sectional view of a wiring board according to an embodiment of the present technology. [Figure 2] It is a cross-sectional view showing the wiring board disassembled. [Figure 3] It is a graph showing the dielectric properties of a dielectric material used as a substrate material. [Figure 4] It is a plan view of a first wiring layer provided in the wiring board. [Figure 5] It is an enlarged cross-sectional view showing a groove of a base material layer provided in the wiring board. [Figure 6] It is a cross-sectional view of the wiring board. [Figure 7] It is a cross-sectional view of the wiring board. [Figure 8] It is an enlarged cross-sectional view showing a groove of a base material layer provided in the wiring board. [Figure 9] It is an enlarged cross-sectional view showing a groove of a base material layer provided in the wiring board. [Figure 10] It is an enlarged cross-sectional view showing a groove of a base material layer provided in the wiring board. [Figure 11] It is an enlarged cross-sectional view showing a manufacturing method by removal processing of the wiring board. [Figure 12] It is an enlarged cross-sectional view showing a manufacturing method by additive processing of the wiring board. [Figure 13] It is a perspective view of a support portion provided in the base material layer of the wiring board. [Figure 14] It is a perspective view of a support portion provided in the base material layer of the wiring board. [Figure 15] It is a perspective view of a support portion provided in the base material layer of the wiring board. [Figure 16] It is a perspective view of a support portion provided in the base material layer of the wiring board. [Figure 17] This is a schematic diagram showing an analysis model related to a comparative example of this technology. [Figure 18] This is a schematic diagram showing an analytical model related to an embodiment of this technology. [Figure 19] This graph shows the simulation analysis results for examples and comparative examples of this technology. [Modes for carrying out the invention]

[0022] The low dielectric constant structure related to this technology can be used as a wiring substrate. A wiring substrate according to an embodiment of this technology will be described below.

[0023] [Wiring board configuration] Figure 1 is a cross-sectional view of the wiring board 100 according to this embodiment, and Figure 2 is a cross-sectional view showing the components of the wiring board 100 in an exploded view. As shown in these figures, the wiring board 100 comprises a base layer 101, a first wiring layer 102, a second wiring layer 103, a first cover layer 104, and a second cover layer 105.

[0024] The substrate layer 101 is a layer made of a dielectric material. Figure 3 is a graph showing the dielectric properties of a dielectric material used as a substrate material. In this figure, the horizontal axis shows the relative permittivity and the vertical axis shows the dielectric loss tangent. Dielectric loss is expressed by a physical quantity called the dielectric loss tangent, and the larger the dielectric loss tangent, the larger the dielectric loss. As shown in the figure, the dielectric loss tangent decreases in this order for RF-4 (Flame Retardant Type 4), polyimide, LCP (Liquid Crystal Polymer), and fluorine-based materials, making them suitable for high-speed signal transmission. The material of the substrate layer 101 may be any of RF-4, polyimide, LCP, or fluorine-based material, but polyimide is particularly preferred.

[0025] As shown in Figure 2, the base layer 101 has a first main surface 101a and a second main surface 101b. The first main surface 101a and the second main surface 101b are main surfaces on opposite sides of the base layer 101. A groove 131 having a predetermined depth is formed in the base layer 101 from the first main surface 101a. This groove 131 will be described later.

[0026] The first wiring layer 102 is arranged on the first main surface 101a. Figure 4 is a plan view of the first wiring layer 102. As shown in the figure, the first wiring layer 102 includes high-speed signal lines 111, low-speed signal lines 112, and ground wiring 113. These wirings extend in the same direction (in this case, the Y direction) and are spaced apart from each other. Note that the configuration of the first wiring layer 102 is not limited to that shown here, and it is sufficient that it includes at least one high-speed signal line 111. These wirings are made of wiring material such as copper or gold.

[0027] The second wiring layer 103 is located on the second main surface 101b. The second wiring layer 103 includes a ground wire 114, which is made of a wiring material such as copper or gold. The configuration of the second wiring layer 103 is not limited to that shown herein and may include multiple signal lines.

[0028] The first cover layer 104 covers the first main surface 101a and the first wiring layer 102, insulating and protecting the first wiring layer 102. The first cover layer 104 is made of any insulating material, for example, the same material as the base layer 101.

[0029] The second cover layer 105 covers the second main surface 101b and the second wiring layer 103, insulating and protecting the second wiring layer 103. The second cover layer 105 is made of any insulating material, for example, the same material as the base layer 101.

[0030] The wiring board 100 has the configuration described above. The structure of the wiring board 100 is not limited to the above, and it is sufficient to have at least a base layer 101 with grooves 131 and a first wiring layer 102. The wiring board 100 may be a flexible substrate or a rigid substrate.

[0031] [About the grooves] As described above, a groove 131 is formed in the base layer 101. Figure 5 is a cross-sectional view showing the groove 131, and is an enlarged view of Figure 1. As shown in the figure, the groove 131 is a portion from the first main surface 101a to the second main surface 101b where no constituent material of the base layer 101 exists, and the inside of the groove 131 is a void.

[0032] As shown in Figure 5, the portion of the base layer 101 that is provided between the grooves 131 and the high-speed signal line 111 and the second main surface 101b, and that supports the high-speed signal line 111, is called the support portion 101c. The grooves 131 are provided on both sides of the support portion 101c and extend along the support portion 101c. That is, as shown in Figure 4, the grooves 131 are provided on both sides of the high-speed signal line 111 when viewed from a direction perpendicular to the first main surface 101a (Z direction), and are arranged so as to sandwich the high-speed signal line 111 when viewed from the same direction. The grooves 131 may not be provided on both sides of the low-speed signal line 112.

[0033] As shown in Figure 5, if the wiring board 100 has two high-speed signal lines 111, the grooves 131 can be arranged in a total of three: one outside each of the two high-speed signal lines 111 and one between the two high-speed signal lines 111. In addition to this arrangement, the grooves 131 can be arranged according to the arrangement of the high-speed signal lines 111. Figures 6 and 7 are cross-sectional views showing other arrangements of the high-speed signal lines 111 and grooves 131.

[0034] As shown in Figure 6, if the wiring board 100 has one high-speed signal line 111, one groove 131 can be provided on each side of the high-speed signal line 111. Also, as shown in Figure 7, if the wiring board 100 has two spaced-apart high-speed signal lines 111, one groove 131 can be provided on each side of each high-speed signal line 111, for a total of four grooves 131. In addition, depending on the arrangement of the high-speed signal lines 111, the grooves 131 can be provided on both sides of the high-speed signal line 111 when viewed from a direction perpendicular to the first main surface 101a (Z direction).

[0035] The cross-sectional shape of the groove 131 is not limited to those described above. Figures 8 and 10 are schematic diagrams showing other cross-sectional shapes of the groove 131. As shown in Figure 8, the groove 131 may have a depth that does not reach the second main surface 101b. Also, as shown in Figure 9, the groove 131 may have a U-shaped cross-sectional shape, and as shown in Figure 10, it may have a V-shaped cross-sectional shape. In addition to these, the groove 131 can have various other cross-sectional shapes.

[0036] [Effects of using a wiring board] As described above, grooves 131 are provided on both sides of the high-speed signal line 111 in the wiring board 100. Generally, the electromagnetic field of an electrical signal transmitted by a signal line is affected by the signal line, the surrounding ground, and the surrounding dielectric material covering the signal line. In particular, suppressing the loss of signal energy within the substrate is important for the transmission of high-frequency signals. By providing grooves 131 on both sides of the high-speed signal line 111, a portion of the dielectric material constituting the base material layer 101 is replaced with air. Since the relative permittivity of air is 1.0 and the dielectric loss tangent is almost zero, it is possible to suppress the loss of signal energy due to the base material layer 101. Therefore, the wiring board 100 has excellent high-frequency signal transmission characteristics.

[0037] Regarding the material for the base layer 101, materials with a low dielectric loss tangent (see Figure 3) are expensive and difficult to process due to their hardness. In the wiring board 100, by providing grooves 131, it is possible to achieve transmission characteristics equivalent to those of materials with a low dielectric loss tangent using materials with a high dielectric loss tangent (see Examples). It is also possible to reduce the dielectric loss tangent of the base layer by incorporating air bubbles, etc., into the base layer (see Prior Art Documents), but in this case, bending stress, fracture strength, and moisture absorption characteristics may deteriorate, and the usable materials are limited. In contrast, the wiring board 100 makes it possible to improve transmission characteristics while suppressing the impact on various properties.

[0038] [Method for forming grooves] The method for forming the groove 131 will now be described. Figures 11 and 12 are schematic diagrams showing the method for forming the groove 131. After the base layer 101 is formed, the groove 131 can be formed by removing the constituent material by irradiating the base layer 101 with a laser L, as shown in Figure 11.

[0039] Laser L is preferably a pulsed laser in which the light source emits light intermittently, and in particular, an ultrashort pulse laser with a short emission time is preferred. An ultrashort pulse laser has an emission time (pulse width) of 10 -12 picosecond lasers in the second range and pulse widths of 10 -15 This includes femtosecond lasers with a time signature in the second range.

[0040] Generally, in laser processing, the longer the pulse width, the faster the processing speed but the lower the processing accuracy. Conversely, the shorter the pulse width, the slower the processing speed but the higher the processing accuracy. When laser processing the resin material that makes up the base layer 101, the pulse width is 10 -9 In the case of nanosecond lasers with pulse widths in the second range, the pulse width is longer than the thermal diffusion time of the material, so heat diffuses through the material before the pulse irradiation is complete. This can lead to melting of the material, cracking, and the accumulation of debris. On the other hand, in the case of picosecond and femtosecond lasers, the pulse width is shorter than the thermal diffusion time of the material, so processing can be completed before heat diffuses through the material. This suppresses deformation of the material and is suitable for forming grooves 131.

[0041] Furthermore, the grooves 131 can also be created by additive manufacturing, as shown in Figure 12, by sequentially layering the constituent materials of the base layer 101. This additive manufacturing can be performed using a 3D printer.

[0042] [Regarding the shape of the support part] The various shapes of the support portion 101c provided on the wiring board 100 will now be described. Figures 13 to 16 are perspective views of the support portion 101c having various shapes. As shown in Figure 13, the support portion 101c can be a wall-like shape extending along the high-speed signal line 111. Also, as shown in Figure 14, the support portion 101c can be a shape having multiple columnar parts spaced apart from each other, with the base material layer 101 removed at regular intervals between the high-speed signal line 111 and the second main surface 101b.

[0043] Furthermore, as shown in Figure 15, the support portion 101c can also be shaped by alternately inclining the columnar portion shown in Figure 14 in a direction perpendicular to the extension direction (Y direction) of the high-speed signal line 111 (X direction) with respect to the thickness direction (Z direction) of the base material layer 101. Also, as shown in Figure 16, the support portion 101c can be shaped by providing a plurality of holes 101d extending in the extension direction (Y direction) of the high-speed signal line 111 in the columnar shape shown in Figure 13. Note that the holes 101d may extend in a direction perpendicular to the extension direction (Y direction) of the high-speed signal line 111 (X direction). In addition, the support portion 101c can be shaped in various ways that can support the high-speed signal line 111.

[0044] As shown in Figures 14 to 16, by creating a bridge structure in which the substrate layer 101 directly beneath the high-speed signal line 111 is partially removed, it is possible to further suppress signal energy loss. Furthermore, by making the support portion 101c into various shapes, the dielectric constant of the substrate layer 101 can be effectively controlled. In addition, by using a bridge structure as shown in Figures 14 to 16, it is possible to adjust properties such as bending stress, fracture strength, and moisture absorption characteristics.

[0045] The shape of the support portion 101c, as shown in Figures 14 to 16, can be formed by adjusting the laser irradiation angle and focal position when using removal processing. When using additive processing, the shape shown in Figures 14 to 16 can be directly formed using a 3D printer.

[0046] [Differentiation] As described above, the inside of the groove 131 can be a void, but it is also possible to fill it with a material different from the base layer 101. In this structure, by using a filler material with a lower dielectric loss tangent than the material of the base layer 101, a reduction in dielectric loss tangent can be obtained. Furthermore, the base layer 101 can also be a dielectric material containing air bubbles (see prior art literature). In this case, in addition to the dielectric loss tangent reduction effect of the groove 131, a reduction in the dielectric loss tangent of the base layer 101 due to the air bubbles can be obtained.

[0047] The low dielectric constant structure related to this technology can be used for applications other than wiring boards. Specifically, a transmission path can be provided in place of the high-speed signal line 111, and this transmission path may include optical waveguides or conductive paths other than signal paths. In this case as well, the dielectric loss tangent of the substrate layer 101 can be reduced by the groove 131. [Examples]

[0048] To verify the effectiveness of this technology, an analysis was conducted using simulations. Figure 17 is a schematic diagram showing analysis model 200 related to the comparative example, and Figure 18 is a schematic diagram showing analysis model 300 related to the example.

[0049] The analysis model 200 shown in Figure 17 has a "basic MSL structure" in which a microstrip line (MSL) is formed, comprising a metal layer 201, a substrate layer 202, and a signal line 203. The metal layer 201 is made of copper and has a width (X direction) of 20 mm and a length (Y direction) of 100 mm. The substrate layer 202 is made of various dielectric materials and has a width (X direction) of 20 mm, a length (Y direction) of 100 mm, and a thickness (Z direction) of 50 μm. The signal line 203 is made of copper and has a width (X direction) of 100 μm, a length (Y direction) of 100 mm, and a thickness (Z direction) of 30 μm.

[0050] The analysis model 300 shown in Figure 18 comprises a metal layer 301, a substrate layer 302, and a signal line 303, and has an "MSL Cut structure" in which the substrate layer 302 on both sides of the signal line 303 is removed. The metal layer 301 is made of copper and has a width (X direction) of 20 mm and a length (Y direction) of 100 mm. The substrate layer 302 is made of various dielectric materials and has a width (X direction) of 100 μm, a length (Y direction) of 100 mm, and a thickness (Z direction) of 50 μm. The signal line 303 is made of copper and has a width (X direction) of 100 μm, a length (Y direction) of 100 mm, and a thickness (Z direction) of 30 μm.

[0051] As the dielectric material constituting the base layer 202 and base layer 302, polyimide (relative permittivity: ε r =3.4, dielectric loss tangent: tanδ=0.02) and liquid crystal polymer: LCP (relative permittivity: ε r Two types were set: (=2.7, dielectric loss tangent: tanδ=0.001).

[0052] Figure 19 is a graph showing the analysis results of the simulation. The horizontal axis represents the signal frequency (Freq.), and the vertical axis represents the transfer characteristics (S21). If S21 is 0 dB, it means that the signal is transmitted without loss. In the figure, "Polyimide" represents the analysis results for the MSL basic structure (see Figure 17) where the substrate layer 202 is polyimide, and "Polyimide Cut" represents the analysis results for the MSL Cut structure (see Figure 18) where the substrate layer 302 is polyimide. Also, in the figure, "LCP" represents the analysis results for the MSL basic structure (see Figure 17) where the substrate layer 202 is LCP, and "LCP Cut" represents the analysis results for the MSL Cut structure (see Figure 18) where the substrate layer 302 is LCP.

[0053] First, as can be seen from all the results, the amount of signal energy loss increases as the signal frequency becomes higher. This is because the signal line becomes more susceptible to the influence of the material properties of the surrounding substrate covering it. For this reason, the substrate wiring structure is more important for high-speed signal transmission than for low-speed signal transmission. Furthermore, when focusing on "polyimide" and "LCP," it can be seen that the polyimide substrate, which has higher dielectric loss, has a greater impact on signal energy loss.

[0054] Figure 21 shows the results for "Polyimide" and "Polyimide Cut," illustrating the effectiveness of this technology. Although both use the same polyimide substrate, "Polyimide Cut" suppresses signal energy loss across all frequency bands, showing an improvement of more than 2 dB at 20 GHz. Furthermore, even with LCP substrates, which originally had low dielectric loss, the results for "LCP" and "LCP Cut" show that the structure of this technology further suppresses signal energy loss, resulting in an improvement of more than 0.5 dB at 20 GHz.

[0055] Based on the above verification results, it can be said that the wiring board structure related to this technology (see Figure 1) is effective for flexible printed circuit boards and rigid circuit boards for high-speed transmission.

[0056] [About this disclosure] The effects described in this disclosure are merely illustrative and not limiting, and other effects may also occur. The description of multiple effects above does not necessarily mean that they will necessarily occur simultaneously. It means that at least one of the effects described above may be obtained depending on the conditions, and effects not described in this disclosure may also occur. Furthermore, it is possible to arbitrarily combine at least two of the feature elements described in this disclosure.

[0057] Furthermore, this technology can also be configured as follows. (1) A substrate layer made of a dielectric material, having a first main surface and a second main surface opposite to the first main surface, It is made of metal and has signal lines provided on the first main surface mentioned above. The substrate layer is provided with grooves on both sides of the signal line, having a predetermined depth from the first main surface when viewed from a direction perpendicular to the first main surface. Wiring board. (2) The wiring board described in (1) above, The above-mentioned substrate layer is made of the above-mentioned dielectric material and has a support portion provided between the above-mentioned grooves, between the above-mentioned signal line and the above-mentioned second main surface, which supports the above-mentioned signal line. Wiring board. (3) The wiring board described in (2) above, The above-mentioned support portion includes a plurality of columnar parts spaced apart from each other. Wiring board. (4) The wiring board described in (3) above, The columnar portion is inclined with respect to the thickness direction of the base material layer. Wiring board. (5) The wiring board described in (3) or (4) above, Holes are provided in the above-mentioned columnar portion. Wiring board. (6) A wiring board described in any one of (1) to (5) above, The above signal lines include high-speed signal lines for transmitting high-frequency signals and low-speed signal lines for transmitting low-frequency signals. The grooves described above are provided on both sides of the high-speed signal line when viewed from the above direction, but not on both sides of the front low-speed signal line when viewed from the above direction. Wiring board. (7) A wiring board described in any one of (1) to (6) above, The dielectric material mentioned above is polyimide. Wiring board. (8) A substrate layer made of a dielectric material, having a first main surface and a second main surface opposite to the first main surface, A transmission line provided on the first main surface described above and The substrate layer is provided with grooves on both sides of the transmission path, having a predetermined depth from the first main surface when viewed from a direction perpendicular to the first main surface. Low dielectric constant structure. (9) A substrate layer is formed from a dielectric material, having a first main surface and a second main surface opposite to the first main surface, with grooves having a predetermined depth extending from the first main surface. A structure is formed on the first main surface described above, in which a signal line made of metal is formed, and grooves are provided on both sides of the signal line when viewed from a direction perpendicular to the first main surface described above. A method for manufacturing a wiring board. (10) A method for manufacturing a wiring board as described in (9) above, In the process of forming the above-mentioned base material layer, the grooves are formed by a removal process that removes the constituent material of the base material layer by laser irradiation. A method for manufacturing a wiring board. (11) A method for manufacturing a wiring board as described in (10) above, The above laser is a pulsed laser. A method for manufacturing a wiring board. (12) A method for manufacturing a wiring board as described in (11) above, The pulsed laser described above is an ultrashort pulse laser. A method for manufacturing a wiring board. (13) A method for manufacturing a wiring board as described in (9) above, In the process of forming the above-mentioned base material layer, the base material layer is formed by an additive processing method that involves laminating the constituent materials of the base material layer. A method for manufacturing a wiring board. [Explanation of Symbols]

[0058] 100... Wiring board 101...Base material layer 101a...first principal surface 101b…Second main surface 101c...Support part 101d…hole 102...1st wiring layer 103…Second wiring layer 104...First Cover Layer 105...Second Cover Layer 111... High-speed signal line 112... Low-speed signal line 113...Ground wiring 114...Ground wiring 131...Groove

Claims

1. A substrate layer made of a dielectric material, having a first main surface and a second main surface opposite to the first main surface, It is made of metal and has signal lines provided on the first main surface. The substrate layer comprises grooves on both sides of the signal line, viewed from a direction perpendicular to the first main surface, having a predetermined depth from the first main surface, the substrate layer is made of the dielectric material, and has a support portion provided between the grooves between the signal line and the second main surface to support the signal line, the support portion includes a plurality of columnar parts spaced apart from each other. Wiring board.

2. A wiring board according to claim 1, The columnar portion is inclined with respect to the thickness direction of the base material layer. Wiring board.

3. A wiring board according to claim 1, Holes are provided in the aforementioned columnar portion. Wiring board.

4. A wiring board according to claim 1, The signal lines include high-speed signal lines for transmitting high-frequency signals and low-speed signal lines for transmitting low-frequency signals. The grooves are provided on both sides of the high-speed signal line when viewed from the aforementioned direction, but not on both sides of the front low-speed signal line when viewed from the aforementioned direction. Wiring board.

5. A wiring board according to claim 1, The dielectric material is polyimide. Wiring board.

6. A substrate layer made of a dielectric material, having a first main surface and a second main surface opposite to the first main surface, The transmission line provided on the first main surface and The substrate layer comprises grooves on both sides of the transmission path, viewed from a direction perpendicular to the first main surface, having a predetermined depth from the first main surface, the substrate layer is made of the dielectric material, and has a support portion provided between the grooves between the transmission path and the second main surface to support the transmission path, the support portion includes a plurality of spaced-apart columnar portions. Low dielectric constant structure.

7. A substrate layer is formed from a dielectric material, having a first main surface and a second main surface opposite to the first main surface, with grooves having a predetermined depth extending from the first main surface. A signal line made of metal is formed on the first main surface, grooves are provided on both sides of the signal line when viewed from a direction perpendicular to the first main surface, and a support portion made of the dielectric material is provided between the grooves and the signal line and the second main surface to support the signal line, the support portion forming a structure including a plurality of columnar parts spaced apart from each other. A method for manufacturing a wiring board.

8. A method for manufacturing a wiring board according to claim 7, In the process of forming the substrate layer, the grooves are formed by a removal process that removes the constituent material of the substrate layer by laser irradiation. A method for manufacturing a wiring board.

9. A method for manufacturing a wiring board according to claim 8, The aforementioned laser is a pulsed laser. A method for manufacturing a wiring board.

10. A method for manufacturing a wiring board according to claim 9, The pulsed laser is an ultrashort pulsed laser. A method for manufacturing a wiring board.

11. A method for manufacturing a wiring board according to claim 7, In the process of forming the base material layer, the base material layer is formed by an additive processing method that involves laminating the constituent materials of the base material layer. A method for manufacturing a wiring board.

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