Transmission line and electronic device

Abstract

A transmission line (101) comprises insulator layers (11, 12, 13), and conductor layers (21, 22, 23) formed on surfaces along the insulator layers (11, 12, 13). A part of the insulator layer (12) between a signal line conductor layer (23) and a reference ground conductor layer (21) is a signal line conductor layer support part (12S) that is in continuous contact with the signal line conductor layer (23) and supports the signal line conductor layer (23). A first main surface of the signal line conductor layer (23) faces the signal line conductor layer support part (12S), and the signal line conductor layer (23) has an exposed surface exposed to a space part (12H). At least a part of a lateral surface of the signal line conductor layer (23), at least a part of the first main surface of the signal line conductor layer (23), or at least a part of the lateral surface and at least a part of the first main surface of the signal line conductor layer (23) are exposed surfaces.

Description

Transmission lines and electronic devices

[0001] The present invention relates to a transmission line and an electronic device including the same.

[0002] A transmission line for high-frequency signals configured on a laminated substrate generally has a structure including a reference ground conductor layer and a signal line conductor layer arranged opposite to the reference ground conductor layer.

[0003] Furthermore, as shown in Patent Document 1, when there are multiple parallel signal line conductor layers, a transmission line is known in which an insulator layer on which the signal line conductor layers are formed has a groove formed in the insulator layer that reaches the reference ground conductor layer. In this way, by replacing the insulator layer near the signal line conductor layer with air, signal energy loss due to the insulator layer is suppressed.

[0004] International Publication No. 2022 / 249532

[0005] In the transmission line disclosed in Patent Document 1, the signal line conductor layer is not in contact with the groove, and therefore the effect of reducing transmission loss due to the provision of the groove is small.

[0006] The inventors of the present invention have discovered an improvement in which transmission loss can be more effectively reduced by forming a space in the insulator layer that forms the signal line conductor layer, taking advantage of the low dielectric constant and dielectric dissipation factor of the space.

[0007] An object of the present invention is to provide a transmission line that can easily reduce transmission loss and an electronic device that includes this transmission line.

[0008] (1) A transmission line as an example of the present disclosure includes a laminate including a plurality of stacked insulator layers and conductor layers formed by bonding to surfaces of all or some of the insulator layers among the plurality of insulator layers, the conductor layers including a reference ground conductor layer and a signal line conductor layer overlapping the reference ground conductor layer when the laminate is viewed in the stacking direction, an insulator layer between the signal line conductor layer and the reference ground conductor layer among the plurality of insulator layers serves as a signal line conductor layer support portion that supports the signal line conductor layer by being in contact with the signal line conductor layer along the signal line conductor layer, a single or multiple space portions are present in a single or multiple insulator layers between the signal line conductor layer and the reference ground conductor layer among the plurality of insulator layers, and the space portion has a portion having a shorter dimension at a remote position in the extension direction of the signal line conductor layer support portion than at a nearby position thereof, the signal line conductor layer has a first main surface and a second main surface that constitute opposing surfaces, and a side surface that connects between the first main surface and the second main surface, the first main surface of the signal line conductor layer faces the signal line conductor layer support portion, the signal line conductor layer has an exposed surface that is exposed to the space portion, and at least a part of the side surface, or at least a part of the first main surface, or at least a part of the side surface and at least a part of the first main surface is the exposed surface.

[0009] (2) A transmission line as an example of the present disclosure includes a laminate including a plurality of stacked insulator layers and conductor layers formed by bonding to surfaces of all or some of the insulator layers among the plurality of insulator layers, the conductor layers including a reference ground conductor layer and a signal line conductor layer overlapping the reference ground conductor layer when the laminate is viewed in the stacking direction, an insulator layer between the signal line conductor layer and the reference ground conductor layer among the plurality of insulator layers serves as a signal line conductor layer support portion that supports the signal line conductor layer by being in contact with the signal line conductor layer along the signal line conductor layer, a single or multiple space portions are present in a single or multiple insulator layers between the signal line conductor layer and the reference ground conductor layer among the plurality of insulator layers, the signal line conductor layer has a first main surface and a second main surface that constitute opposing surfaces, and a side surface that connects between the first main surface and the second main surface, the first main surface of the signal line conductor layer faces the signal line conductor layer support portion, and the signal line conductor layer has an exposed surface exposed in the space portion, At least a portion of the side surface, or at least a portion of the first main surface, or at least a portion of the side surface and at least a portion of the first main surface is the exposed surface, and in the space portion, the second main surface of the signal line conductor layer is in contact with one or more of the plurality of insulator layers.

[0010] (3) An electronic device as an example of the present disclosure includes the transmission line and an electronic circuit connected to the transmission line.

[0011] According to the present invention, a transmission line with lower transmission loss and an electronic device including the same can be obtained.

[0012] FIG. 1A is a plan view of each layer showing the configuration of the transmission line according to the first embodiment. FIG. 1B is a cross-sectional view of each layer before lamination, showing the configuration of the transmission line according to the first embodiment. FIG. 1C is a cross-sectional view of the transmission line 101 according to the first embodiment. FIG. 2A is a plan view of the transmission line according to the first embodiment, and FIG. 2B is a plan view of the transmission line at a stage before lamination of an insulating layer on the surface of the transmission line. FIG. 3A is a cross-sectional view taken along line Y1-Y1 in FIG. 1A, FIG. 3B is a cross-sectional view taken along line Y2-Y2 in FIG. 1A, FIG. 3C is a cross-sectional view taken along line Y3-Y3 in FIG. 1A, and FIG. 3D is a cross-sectional view taken along line Y4-Y4 in FIG. 1A. FIG. 4 is a partially enlarged view of the plan view shown in FIG. 2B. FIGS. 5A, 5B, 5C, and 5D are cross-sectional views of the transmission line according to the first embodiment and its intermediate stages of manufacture. FIG. 6(A) is a partial plan view of the transmission line shown in FIG. 1(C) with components mounted on both ends. FIG. 6(B) is a cross-sectional view taken along Y1-Y1 in FIG. 6(A), and FIG. 6(C) is a cross-sectional view taken along Y2-Y2 in FIG. 6(A). FIG. 7(A) is a partial enlarged view of the plan view shown in FIG. 2(B). FIG. 7(B) is a cross-sectional view taken along Y2-Y2 in FIG. 7(A). FIG. 7(C) is a partial enlarged view of FIG. 7(B). FIG. 8(A) is a grayscale diagram showing the results of a simulation of the electric field intensity and its distribution (i.e., electric field density) between the signal line conductor layer and the reference ground conductor layer of the transmission line according to the first embodiment. FIG. 8(B) is a partial enlarged view of the vicinity of a corner of the signal line conductor layer in FIG. 8(A). FIGS. 9(A), 9(B), 9(C), and 9(D) are cross-sectional views of a transmission line according to a second embodiment and its intermediate stages of manufacture. Fig. 10(A) is a cross-sectional view of a transmission line according to a third embodiment, and Fig. 10(B) is a cross-sectional view of the transmission line according to the third embodiment. Fig. 11(A) is a cross-sectional view of a transmission line according to a fourth embodiment, and Fig. 11(B) is a cross-sectional view of the transmission line according to the fourth embodiment. Fig. 12 is a cross-sectional view of a transmission line according to a fifth embodiment. Fig. 13(A) is a cross-sectional view of a transmission line according to a sixth embodiment, and Fig. 13(B) is a cross-sectional view of the transmission line according to the sixth embodiment. Fig. 14(A) is a cross-sectional view of a transmission line according to a seventh embodiment, and Fig. 14(B) is a partially enlarged view of Fig. 14(A).FIG. 14(C) is a further enlarged partial view of FIG. 14(B). FIGS. 15(A), 15(B), 15(C), and 15(D) are all partial cross-sectional views of a transmission line according to an eighth embodiment. FIGS. 16(A), 6(B), 16(C), 6(D), and 16(E) are cross-sectional views of a transmission line according to a ninth embodiment. FIGS. 17(A), 17(B), 17(C), 17(D), 17(E), 17(F), 17(G), and 17(H) are plan views of a transmission line according to a tenth embodiment. FIGS. 18(A), 18(B), and 18(C) are plan views of a transmission line according to an eleventh embodiment. FIGS. 19(A), 19(B), 19(C), and 19(D) are cross-sectional views of a transmission line according to a twelfth embodiment. FIG. 20A is a plan view of the insulator layers on which the conductor layers are formed before lamination. FIG. 20B is a cross-sectional view of the transmission line according to the thirteenth embodiment during its manufacture. FIG. 20C is a cross-sectional view of the transmission line 108 according to the thirteenth embodiment. FIG. 21 is a cross-sectional view taken along line Y2-Y2 in FIG. 20A. FIG. 22 is a plan view of the transmission line according to the fourteenth embodiment. FIGS. 23A, 23B, and 23C are cross-sectional views of the transmission line according to the fourteenth embodiment and during its manufacture. FIG. 24 is a plan view of each layer showing the configuration of the transmission line according to the fifteenth embodiment. FIG. 25 is a cross-sectional view taken along line Y2-Y2 in FIG. 24. FIG. 26 is a plan view of each layer showing the configuration of the transmission line according to the sixteenth embodiment. FIG. 27 is a cross-sectional view showing the configuration of three transmission lines according to the seventeenth embodiment. FIG. 28 is a cross-sectional view of an electronic device according to the eighteenth embodiment.

[0013] Hereinafter, several specific examples will be given with reference to the drawings to illustrate several embodiments for carrying out the present invention. The same reference numerals are used for the same parts in each drawing. To facilitate explanation and understanding of the main points, the embodiments for carrying out the present invention are shown divided into several embodiments for the sake of convenience. However, partial omission, substitution, or combination of the configurations shown in different embodiments is possible. From the second embodiment onwards, descriptions of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects resulting from similar configurations will not be mentioned in each embodiment.

[0014] First Embodiment Fig. 1(A) is a plan view of each layer showing the configuration of a transmission line according to the first embodiment. Fig. 1(B) is a cross-sectional view of each layer before lamination, showing the configuration of the transmission line according to the first embodiment. Fig. 1(C) is a cross-sectional view of a transmission line 101 according to the first embodiment. Both Fig. 1(B) and Fig. 1(C) are cross-sectional views taken along line X-X in Fig. 1(A). Note that in Fig. 1(A), the conductor layers are shown separated from the insulator layers.

[0015] FIG. 2A is a plan view of the transmission line 101, and FIG. 2B is a plan view of the transmission line 101 at a stage before an insulating layer is laminated on the surface of the transmission line 101.

[0016] Fig. 3(A) is a cross-sectional view taken along line Y1-Y1 in Fig. 1(A), Fig. 3(B) is a cross-sectional view taken along line Y2-Y2 in Fig. 1(A), Fig. 3(C) is a cross-sectional view taken along line Y3-Y3 in Fig. 1(A), and Fig. 3(D) is a cross-sectional view taken along line Y4-Y4 in Fig. 1(A). Of course, all of these are cross-sectional views after the layers have been stacked to form a laminate (in a state where transmission line 101 has been configured).

[0017] In each cross-sectional view, lines that appear in the cross section (appearing due to cutting) are drawn, and lines that exist behind the cross section are not shown. This also applies to each embodiment described later. In addition, the directional symbols X, Y, and Z in each view merely indicate the direction from which each view is taken, and do not indicate the origin of the three orthogonal axes.

[0018] Although each figure shows a single transmission line, in the intermediate stage of manufacturing such a single transmission line, the continuous line is made up of multiple transmission lines, and the continuous line is cut into single lines at the final stage of the manufacturing process or just before the final stage. This relationship between the continuous line and single lines is similar in other figures.

[0019] In the first embodiment, the transmission line 101 includes three insulator layers 11, 12, and 13. One surface of the insulator layer 11 and one surface of the insulator layer 12 include various conductor layers that are bonded and patterned.

[0020] As shown in Fig. 1B, a signal line conductor layer 23 and a side ground conductor layer 22 are provided on the insulator layer 12. As shown in Fig. 1A, the signal line conductor layer 23 is a conductor pattern that extends in the X direction with a constant width. Both ends of this signal line conductor layer 23 act as signal electrodes. These signal electrodes will be described in detail later.

[0021] 1A and 1B, a main ground conductor layer 21 is provided on the insulator layer 11. The main ground conductor layer 21 is a conductor layer formed over substantially the entire surface of one side of the insulator layer 11. The side ground conductor layers 22 are provided in positions surrounding the signal line conductor layer 23 when viewed in the stacking direction (Z direction) of the laminate.

[0022] A plurality of spaces 12H are formed in the insulator layer 12 and arranged along the extension direction of the signal line conductor layer 23. In this example, the spaces 12H are semi-cylindrical through-holes. These spaces 12H are arranged on both sides of the signal line conductor layer 23 when viewed in the stacking direction (Z direction) of the laminate.

[0023] The insulator layer 12 between the signal line conductor layer 23 and the reference ground conductor layer 21 is in continuous contact with the signal line conductor layer 23 along the extension direction of the signal line conductor layer 23. In other words, the signal line conductor layer 23 is continuously supported by the signal line conductor layer support portion 12S.

[0024] As shown in Figures 1(A), 3(B), and 3(D), the space 12H formed in the insulator layer 12 forms a hollow space when the insulator layers 11, 12, and 13 on which various conductor layers are formed are stacked. That is, each space 12H is a semi-cylindrical space filled with air. The shape of this space 12H is an example. Focusing on the length of the space 12H in the direction along the signal line conductor layer support portion 12S (X direction), the length at a position away from the signal line conductor layer support portion 12S is shorter than the length at a position close to the signal line conductor layer support portion 12S.

[0025] The aforementioned length comparison will now be explained using the drawings. Figure 4 is a partially enlarged view of the plan view shown in Figure 2(B). In Figure 4, X1-X1 and X2-X2 are both line segments in the extension direction of the signal line conductor layer support portion 12S. The position of the line segment X1-X1 is near the signal line conductor layer support portion 12S, and the position of the line segment X2-X2 is far from the signal line conductor layer support portion 12S.

[0026] The dimension of the space 12H along the line segment X1-X1 is 12Hy1, and the dimension of the space 12H along the line segment X2-X2 is 12Hy2, where 12Hy2<12Hy1.

[0027] In this way, the space 12H has a portion that is shorter in dimension at a position farther away from the signal line conductor layer supporting portion 12S in the extending direction (X direction) of the signal line conductor layer supporting portion 12S than at a position close to the signal line conductor layer supporting portion 12S.

[0028] 1A, a plurality of openings 13H are formed in the insulator layer 13. These openings 13H expose both ends of the signal line conductor layer 23 and parts of the side ground conductor layer 22. This exposure forms electrodes for mounting components, which will be described in detail later.

[0029] The space 12H and the opening 13H are resin-removed portions, and are formed by, for example, laser cutting, wet etching, dry etching, sandblasting, drilling, punching, or other processing.

[0030] The signal line conductor layer 23 faces the main ground conductor layer 21 in the thickness direction of the insulator layer 12. In the first embodiment, the signal line conductor layer 23 and the main ground conductor layer 21 face each other with the insulator layer 12 interposed therebetween.

[0031] The side ground conductor layer 22 faces the main ground conductor layer 21 in the thickness direction of the insulator layer 12. In the first embodiment, the side ground conductor layer 22 and the main ground conductor layer 21 face each other with the insulator layer 12 interposed therebetween.

[0032] The side ground conductor layers 22 are arranged along the extension direction (X direction) of the signal line conductor layers 23 and at positions spaced a predetermined distance from the signal line conductor layers 23 in the left-right direction (Y direction).

[0033] The side ground conductor layer 22 acts as a shielding ground conductor. The transmission line according to the first embodiment acts as a microstrip line. That is, the microstrip line is mainly composed of the reference ground conductor layer 21, the signal line conductor layer 23, the insulator layer 12, and the insulator layer 13. The insulator layer 11 mainly acts as a protective layer.

[0034] An electric field is also generated between the signal line conductor layer 23 and the side ground conductor layer 22. However, compared to the distance between the signal line conductor layer 23 and the reference ground conductor layer 21, the distance between the signal line conductor layer 23 and the side ground conductor layer 22 is wider and the opposing area in terms of the electric field is smaller. Therefore, although the side ground conductor layer 22 is part of the transmission line, it acts as a shielding ground conductor.

[0035] 5A, 5B, 5C, and 5D are cross-sectional views of the transmission line 101 and its manufacturing process, all of which are cross-sectional views taken along the line Y2-Y2 shown in FIG.

[0036] First, as shown in FIG. 5A , the reference ground conductor layer 21 is formed by patterning a conductor layer bonded to the insulator layer 11. The signal line conductor layer 23 and the side ground conductor layer 22 are formed by patterning a conductor layer bonded to the insulator layer 12. The insulator layers 11, 12, and 13 are made of a resin material with a low dielectric constant and dielectric loss tangent, such as LCP or PTFE. The insulator layers 11, 12, and 13 are made of a thermoplastic resin. The conductor layers 21, 22, and 23 are made of a metal foil, such as copper foil or aluminum foil.

[0037] Next, as shown in FIG. 5B , the insulator layer 12 having the signal line conductor layer 23 and the side ground conductor layer 22 formed thereon is stacked on the insulator layer 11 having the main ground conductor layer 21 formed thereon, and the joining surfaces are joined by applying pressure and heat.

[0038] 5C, a space 12H is formed in the insulator layer 12. For example, the space 12H is formed by laser cutting, wet etching, dry etching, sandblasting, or other processing. When the space 12H is formed, the signal line conductor layer 23 acts as a mask.

[0039] At this stage, an interlayer connection conductor (the interlayer connection conductor 4 shown in Figures 3(A) and 3(C), etc.) that electrically connects the main ground conductor layer 21 and the side ground conductor layer 22 is formed by electroplating or the like.

[0040] 5(D), the insulator layer 13 is laminated on the insulator layer 12, and the bonding surfaces are bonded by applying pressure and heat to form the space 12H. In this state, the insulator layers 11, 12, and 13 do not have a path through which gas can pass between the space 12H and the outside, and the space 12H is airtight.

[0041] 1C, 3C, and 3D, an opening 13H is formed in the insulator layer 13. For example, the opening 13H is formed by laser cutting, wet etching, dry etching, sandblasting, or other processes. As a result, the exposed portion of the signal line conductor layer 23 is formed as the signal electrode 23E. Also, the exposed portion of the side ground conductor layer 22 is formed as the ground electrode 22E.

[0042] In this manner, the transmission line 101 is manufactured.

[0043] The interlayer connection conductors 4 are arranged at predetermined intervals in the extending direction of the signal line conductor layer 23. It is preferable that these intervals be narrow enough to prevent almost no leakage of electromagnetic waves in the frequency band of the high-frequency signal propagating through the transmission line to the side (Y direction).

[0044] Fig. 6(A) is a partial plan view showing a state in which components 9 are mounted on both ends of the transmission line 101 shown in Fig. 1(C). Fig. 6(B) is a cross-sectional view taken along line Y1-Y1 in Fig. 6(A), and Fig. 6(C) is a cross-sectional view taken along line Y2-Y2 in Fig. 6(A).

[0045] The mounted component 9 is, for example, one side of a connector. Three ground terminals 9G and one signal terminal 9S protrude from the mounted component 9. This connector is, for example, a coaxial connector, but the electrodes of the connector are not shown in Figure 6(A).

[0046] 6B, a ground electrode 22E is an exposed portion of the side ground conductor layer 22. A ground terminal 9G of the mounted component is joined to the ground electrode 22E with solder S.

[0047] 6C, the exposed portion of the signal line conductor layer 23 is a signal electrode 23E. A signal terminal 9S of the mounted component is joined to this signal electrode 23E with solder S.

[0048] Fig. 7(A) is a partially enlarged view of the plan view shown in Fig. 2(B). Fig. 7(B) is a cross-sectional view taken along line Y2-Y2 in Fig. 7(A). However, Fig. 7(B) is a cross-sectional view showing a state in which the topmost insulator layer 13 has been laminated. Fig. 7(C) is a partially enlarged view of Fig. 7(B).

[0049] The signal line conductor layer 23 has a first main surface S1 and a second main surface S2 that are opposite to each other, and a side surface SS that connects between the first main surface S1 and the second main surface S2. The side surface SS is one of both end surfaces of the signal line conductor layer 23 in the line width direction (Y direction).

[0050] The insulating layer 12 and the insulating layer 13 are in close contact with each other at the contact portion RJ without any conductor layer therebetween.

[0051] 7A and 7B, the boundary between the space 12H and both sides of the signal line conductor layer 23 is a high electric field density portion EF. The electric field density in this high electric field density portion EF is higher than that in regions distant in the Y direction from the boundary between the space 12H and both sides of the signal line conductor layer 23.

[0052] As shown in FIG. 7C, exposed surfaces ES, which are parts of both side surfaces of the signal line conductor layer 23 in the width direction (Y direction), are exposed to the space 12H.

[0053] To explain one of the features of the transmission line of this embodiment, a typical electric field density distribution of a typical microstrip line will be described with reference to FIGS. 8A and 8B. FIG. 8A is a grayscale diagram showing the results of a simulation of the electric field strength and its distribution (i.e., electric field density) between the signal line conductor layer 23 and the reference ground conductor layer 21. FIG. 8B is a partially enlarged view of the vicinity of a corner of the signal line conductor layer in FIG. 8A. In FIGS. 8A and 8B, the higher the electric field density, the higher the density. Note that the vertical line in the center of the horizontal direction in FIG. 8A is a line that appears in the simulation.

[0054] The signal line conductor layer 23 and the main ground conductor layer 21 face each other at a relatively short distance, so the electric field density therebetween is high. The electric field density is particularly high near the corners of the signal line conductor layer 23, and the electric field density is highest near the corner closest to the main ground conductor layer 21.

[0055] The features of the first embodiment are as follows.

[0056] (a) At least a portion of the side of the signal line conductor layer 23 has an exposed surface ES exposed to the space 12H. That is, the area with high electric field density is exposed to air with a low dielectric constant and dielectric loss tangent. This reduces dielectric loss and, therefore, transmission loss. Meanwhile, since the signal line conductor layer support portion has a shorter portion at a more distant position than at a more proximal position in the extension direction of the signal line conductor layer support portion, the mechanical strength of the laminate can be maintained. When the transmission line is bent, the presence of the space 12H may cause a misalignment between the signal line conductor layer 23 and the side ground conductor layer 22. However, since the proportion of the space 12H in the insulator layer 12 at a more distant position in the extension direction of the signal line conductor layer support portion is smaller than that at a more proximal position, this misalignment is reduced.

[0057] (b) The insulator layer 12 between the signal line conductor layer 23 and the reference ground conductor layer 21 is in continuous contact with the signal line conductor layer 23 along the extension direction of the signal line conductor layer 23. In other words, the signal line conductor layer 23 is continuously supported by the signal line conductor layer support portion 12S. This increases the support strength of the insulator layer 12 for the signal line conductor layer 23, suppresses unnecessary deformation of the signal line conductor layer 23, and ensures stable electrical characteristics of the transmission line.

[0058] (c) Since the spaces 12H are discretely arranged between the signal line conductor layer 23 and the reference ground conductor layer 21, the support strength of the signal line conductor layer 23 is high, unnecessary deformation of the signal line conductor layer 23 is suppressed, and stable electrical characteristics of the transmission line can be ensured.

[0059] (d) Since the space 12H has a semi-cylindrical shape, the insulating layers 11, 12, and 13 have high resistance to bending stress in the surface direction.

[0060] (e) Because the space 12H has a semi-cylindrical shape, it can be easily processed using a generally circular laser beam. That is, the left and right space 12H sandwiching the signal line conductor layer 23 can be processed simultaneously. Furthermore, because two adjacent space 12H are joined together to form a cylindrical shape, there is no directionality, and there is no need to change the processing direction regardless of the direction of the signal line conductor layer 23.

[0061] (f) For example, by pressing an insulator layer made of a thermoplastic resin at high temperature to soften it, a portion of the signal line conductor layer 23 can be embedded in the insulator layer. This increases the support strength of the insulator layer 13 for the signal line conductor layer 23, suppresses unnecessary deformation of the signal line conductor layer 23, and ensures stable electrical characteristics of the transmission line. As mentioned above, although the electric field density is high at the corners of the signal line conductor layer 23, the electric field density is lower at the corners buried in the insulator layer 13 than at the corners exposed in the space 12H, so the effect of suppressing dielectric loss is maintained.

[0062] 7(B), the interface between the insulator layer 13 and the insulator layer 12 is also a surface that is continuous with the interface of the space portion 12H. Because the interface between the insulator layer 13 and the insulator layer 12 is a fusion surface between resins, i.e., it is not an interface between a conductor layer and an insulator layer, the adhesive strength of the adhesive joint RJ where the insulator layer 12 and the insulator layer 13 are in close contact is high. Therefore, even if the air in the space portion 12H expands, peeling at the interface between the insulator layer 13 and the insulator layer 12 is unlikely to occur.

[0063] (h) Since the space 12H is sealed, gas and water vapor cannot enter the space 12H, and corrosion of the conductor layer made of copper foil or the like is prevented.

[0064] (i) Since the interlayer connection conductor 4 is formed on only one insulating layer, the number of processing steps is small and the manufacturing cost is low.

[0065] (j) The interlayer connection conductors 4 may be processed using a conductive paste or by copper plating. Since the signal line conductor layer 23 does not require an interlayer connection conductor, when the interlayer connection conductors 4 are processed by copper plating, no electrical connection processing for electroplating is required, which makes processing easier.

[0066] (k) The insulator layers 11, 12, and 13 are made of a resin with a low dielectric constant and dielectric loss tangent, such as LCP or PTFE, which reduces the dielectric loss in the insulator layers and thereby reduces transmission loss.

[0067] (l) By using a thermoplastic resin such as LCP for the insulating layers 11, 12, and 13, the insulating layers can be self-adhered to each other without using an adhesive.

[0068] (m) By using a material with low water absorption or low gas permeability, such as LCP, for the insulating layers 11, 12, and 13, the sealing performance of the space 12H can be improved.

[0069] (n) Since the signal line conductor layer 23 is fixed by being sandwiched between the upper and lower insulating layers 12 and 13, displacement and deformation of the signal line conductor layer 23 are suppressed.

[0070] Second Embodiment In a second embodiment, a transmission line in which a signal line conductor layer, a reference ground conductor layer, and a side ground conductor layer are formed on the same insulating layer will be exemplified.

[0071] 9A, 9B, 9C, and 9D are cross-sectional views of the transmission line 102 according to the second embodiment and during its manufacturing process, all of which are cross-sectional views taken along the line Y2-Y2 shown in FIG. 1A in the first embodiment.

[0072] First, as shown in FIG. 9A , the reference ground conductor layer 21 is formed by patterning a conductor layer bonded to the lower surface of the insulator layer 12. The signal line conductor layer 23 and the side ground conductor layer 22 are formed by patterning a conductor layer bonded to the upper surface of the insulator layer 12. No conductor layer is formed on the insulator layers 11 and 13. The insulator layers 11, 12, and 13 are made of a resin material with a low dielectric constant and dielectric loss tangent, such as LCP or PTFE. The insulator layers 11, 12, and 13 are made of a thermoplastic resin. The conductor layers 21, 22, and 23 are made of a metal foil, such as copper foil or aluminum foil.

[0073] Next, as shown in FIG. 9B , the insulator layer 12 on which the signal line conductor layer 23, the reference ground conductor layer 21, and the side ground conductor layer 22 are formed is stacked on the insulator layer 11, and the bonding surfaces are bonded by applying pressure and heat.

[0074] 9C, a space 12H is formed in the insulator layer 12. For example, the space 12H is formed by laser cutting, wet etching, dry etching, sandblasting, or other processing. When the space 12H is formed, the signal line conductor layer 23 acts as a mask.

[0075] At this stage, an interlayer connection conductor (the interlayer connection conductor 4 shown in FIGS. 3A and 3C in the first embodiment) that electrically connects the main ground conductor layer 21 and the side ground conductor layer 22 is formed by electroplating or the like.

[0076] Thereafter, as shown in FIG. 9D, the insulating layer 13 is laminated on the insulating layer 12, and the bonding surfaces are bonded together by applying pressure and heat, thereby forming a space 12H.

[0077] Although not shown here, an opening 13H is then formed in the insulator layer 13 as shown in FIGS. 1C and 3C in the first embodiment. For example, the opening 13H is formed by laser cutting, wet etching, dry etching, sandblasting, or other processes. As a result, the exposed portion of the signal line conductor layer 23 is formed as the signal electrode 23E. Also, the exposed portion of the side ground conductor layer 22 is formed as the ground electrode 22E.

[0078] In this manner, the transmission line 102 is manufactured.

[0079] According to the second embodiment, only one substrate is required for forming the conductor layer before lamination, and therefore the manufacturing cost is low.

[0080] Third Embodiment In a third embodiment, a transmission line in which a surface insulator layer is made of an insulator layer made of a material different from that of other insulator layers will be exemplified.

[0081] FIG. 10A is a cross-sectional view of a transmission line 103A according to the third embodiment, and FIG. 10B is a cross-sectional view of a transmission line 103B according to the third embodiment.

[0082] 10A and 10B are cross-sectional views of the transmission line at a position corresponding to the cross-sectional position Y2-Y2 of the transmission line 101 shown in FIG. 1A in the first embodiment.

[0083] 10A, a reference ground conductor layer 21 is formed by patterning a conductor layer bonded to the lower surface of the insulator layer 12. Furthermore, a signal line conductor layer 23 and a side ground conductor layer 22 are formed by patterning a conductor layer bonded to the upper surface of the insulator layer 12. The lower surface of the insulator layer 12 is covered with an insulator layer 11 made of a coverlay such as polyimide. The upper surface of the insulator layer 12 is also covered with an insulator layer 13 made of a coverlay (protective film) such as polyimide.

[0084] 10B, a reference ground conductor layer 21 is formed by patterning a conductor layer bonded to the lower surface of the insulator layer 12. Furthermore, a signal line conductor layer 23 and a side ground conductor layer 22 are formed by patterning a conductor layer bonded to the lower surface of the insulator layer 13. The lower surface of the insulator layer 12 is then coated with an insulator layer 11 made of a coverlay such as polyimide.

[0085] According to the third embodiment, the outer insulating layer can be attached by press processing at low temperature and low pressure, which eliminates the need for expensive equipment and reduces manufacturing costs. In addition, the energy required for processing can be reduced, which also reduces manufacturing costs.

[0086] Fourth Embodiment In a fourth embodiment, a transmission line in which a plurality of insulating layers exist between the reference ground conductor layer 21 and the signal line conductor layer 23 will be illustrated.

[0087] 11A is a cross-sectional view of a transmission line 104A according to the fourth embodiment, and FIG. 11B is a cross-sectional view of a transmission line 104B according to the fourth embodiment, both of which are cross-sectional views taken along a line Y2-Y2 of the transmission line shown in FIG. 1A according to the first embodiment.

[0088] 11A, similarly to the transmission line 101 shown in the first embodiment, a reference ground conductor layer 21 is formed on the upper surface of the insulator layer 11, and a signal line conductor layer 23 and a side ground conductor layer 22 are formed on the upper surface of the insulator layer 12. Unlike the transmission line 101 shown in the first embodiment, the transmission line 104A additionally has an insulator layer 14 inserted between the insulator layer 11 and the insulator layer 12. The reference ground conductor layer 21 and the side ground conductor layer 22 are electrically connected via an interlayer connection conductor not shown.

[0089] 11B , similar to the transmission line 101 shown in the first embodiment, a reference ground conductor layer 21 is formed on the top surface of the insulator layer 11, and a signal line conductor layer 23 and a side ground conductor layer 22A are formed on the top surface of the insulator layer 12. Unlike the transmission line 101 shown in the first embodiment, the transmission line 104B further includes an insulator layer 14 between the insulator layer 11 and the insulator layer 12. A side ground conductor layer 22B is formed on the top surface of this insulator layer 14. The reference ground conductor layer 21 and the side ground conductor layers 22A and 22B are electrically connected via interlayer connection conductors (not shown).

[0090] According to the fourth embodiment, because the number of insulator layers between the signal line conductor layer 23 and the reference ground conductor layer 21 is large, the thickness of the insulator layers between the signal line conductor layer 23 and the reference ground conductor layer 21 can be increased to a predetermined thickness even when using only thin insulator layers. Furthermore, since it is possible to form conductor patterns on each insulator layer and bond these conductor patterns to the insulator layers, a predetermined circuit can be configured by forming conductor patterns on the insulator layers. Furthermore, by electrically connecting the side ground conductor layers 22A and 22B using interlayer connection conductors that pass through the insulating layers, the ground conductors are expanded in the thickness direction (the stacking direction of the insulator layers), thereby improving shielding properties.

[0091] Furthermore, by increasing the thickness of the insulator layer between the signal line conductor layer 23 and the reference ground conductor layer 21 to a predetermined thickness, the electric field density between the signal line conductor layer 23 and the reference ground conductor layer 21 is reduced, reducing the dielectric loss therebetween and effectively reducing transmission loss. Furthermore, the line width of the signal line conductor layer 23 is increased to optimize the capacitance between the signal line conductor layer 23 and the reference ground conductor layer 21, thereby reducing the conductor loss of the signal line conductor layer 23 and effectively reducing transmission loss.

[0092] Fifth Embodiment In a fifth embodiment, a transmission line in which insulator layers adjacent in the stacking direction are joined together via an adhesive layer will be exemplified.

[0093] 12 is a cross-sectional view of a transmission line 105 according to the fifth embodiment. The cross-sectional position corresponds to the position Y2-Y2 of the transmission line 101 shown in FIG. 1A in the first embodiment.

[0094] In the transmission line 105, similarly to the transmission line 101 described in the first embodiment, a reference ground conductor layer 21 is formed on the upper surface of the insulator layer 11, and a signal line conductor layer 23 and a side ground conductor layer 22 are formed on the upper surface of the insulator layer 12.

[0095] The insulator layer 11 on which the main ground conductor layer 21 is formed and the insulator layer 12 on which the signal line conductor layer 23 and the side ground conductor layer 22 are formed are bonded together via an adhesive layer 51. The insulator layer 12 on which the signal line conductor layer 23 and the side ground conductor layer 22 are formed and the insulator layer 13 are bonded together via an adhesive layer 52.

[0096] The transmission line 105 may be manufactured, for example, as follows.

[0097] First, the main ground conductor layer 21 is formed on the insulator layer 11 , and the side ground conductor layer 22 is formed on the insulator layer 12 .

[0098] Next, the insulator layer 11 on which the main ground conductor layer 21 is formed and the insulator layer 12 on which the side ground conductor layer 22 is formed are bonded together via an adhesive layer 51 .

[0099] Next, an opening for forming the space 12H is formed in the insulator layer 12. Also, a via hole is opened and the inside of the via hole is plated to form an interlayer connection conductor.

[0100] Thereafter, the insulator layer 12 on which the side ground conductor layer 22 is formed and the insulator layer 13 are bonded together via the adhesive layer 52 .

[0101] At an initial stage when the adhesive layers 51 and 52 are in a film state, openings for forming part of the space 12H may be formed in the adhesive layers 51 and 52 .

[0102] The insulator layers 11, 12, and 13 are made of a resin with a low dielectric constant and dielectric loss tangent, such as LCP, MPI, PI, or PTFE. The adhesive layers 51 and 52 are made of a thermosetting resin, such as an epoxy resin or an acrylic resin. While the adhesive layers 51 and 52 may be applied to the surfaces of the insulator layers, it is preferable to heat the layers after laminating them in film form. This facilitates uniform spacing between the main ground conductor layer 21 and the signal line conductor layer 23, and between the main ground conductor layer 21 and the side ground conductor layer 22.

[0103] As described above, in the fifth embodiment, the insulating layers 11, 12, and 13 are laminated via the adhesive layers 51 and 52 made of a material different from that of the insulating layers 11, 12, and 13.

[0104] According to the fifth embodiment, the pressure required for bonding the conductor layer and the insulator layer or the insulator layers to each other is small, so deformation of the space 12H is small, which makes it easier to stabilize the electrical characteristics of the waveguide.

[0105] Sixth Embodiment In a sixth embodiment, a transmission line in which the hollow portion does not reach the reference ground conductor layer will be exemplified.

[0106] 13A is a cross-sectional view of a transmission line 106A according to the sixth embodiment, and FIG. 13B is a cross-sectional view of a transmission line 106B according to the sixth embodiment, both of which are cross-sectional views taken along the line Y2-Y2 of the transmission line 101 shown in FIG.

[0107] 13A, the transmission line 106A has a reference ground conductor layer 21 formed on the upper surface of the insulator layer 11, and a signal line conductor layer 23 and a side ground conductor layer 22 formed on the upper surface of the insulator layer 12. An insulator layer 14 is laminated between the insulator layer 11 and the insulator layer 12. However, no opening is formed in the insulator layer 14. With this structure, the space 12H exists only midway between the signal line conductor layer 23 and the reference ground conductor layer 21. In other words, the space 12H does not reach from the signal line conductor layer 23 to the reference ground conductor layer 21.

[0108] 13B , a transmission line 106B has a reference ground conductor layer 21 formed on the upper surface of the insulator layer 11, and a signal line conductor layer 23 and a side ground conductor layer 22 formed on the upper surface of the insulator layer 12. A non-penetrating opening is formed in the insulator layer 12, and a space 12H is formed by laminating the insulator layer 12 and the insulator layer 13. In other words, the space 12H does not extend from the signal line conductor layer 23 to the reference ground conductor layer 21.

[0109] In this way, even in the case of a transmission line in which the space 12H does not reach the reference ground conductor layer 21, the space 12H exists in the portion of high electric field density, and therefore the loss reduction effect of the space 12H can be utilized.

[0110] According to the sixth embodiment, the main ground conductor layer 21 is covered with an insulating layer, and therefore the main ground conductor layer 21 has high corrosion resistance.

[0111] Furthermore, in the transmission line 106B shown in FIG. 13B, the number of self-adhesive layers between the insulator layers is small, so press processing at high temperature and high pressure is not required, and in that respect processing is easy.

[0112] Seventh Embodiment In a seventh embodiment, a transmission line in which the exposed structure of the signal line conductor layer relative to the hollow portion is different from the examples shown so far will be exemplified.

[0113] Fig. 14A is a cross-sectional view of a transmission line 107 according to the seventh embodiment, Fig. 14B is a partially enlarged view of Fig. 14A, and Fig. 14C is a further partially enlarged view of Fig. 14B.

[0114] As shown in FIG. 14B, in the line width of the signal line conductor layer 23, the width 23W of the first main surface S1 is larger than the width 12SW of the signal line conductor layer supporting portion 12S.

[0115] As shown in FIG. 14C, the signal line conductor layer 23 has an exposed surface ESS in part of the side surface SS, and an exposed surface ESB in part of the first main surface S1.

[0116] That is, a corner 23C connecting the side surface SS and the first main surface S1 of the signal line conductor layer 23 is exposed to the space 12H.

[0117] In this example, the corner 23C connecting the side surface SS of the signal line conductor layer 23 to the first main surface S1 is an acute angle.

[0118] According to the seventh embodiment, compared to the examples shown so far, the exposed area of ​​the signal line conductor layer 23 to the air, which has a low dielectric constant and dielectric loss tangent, is large in the high electric field density portion EF (see FIG. 14(B)), and therefore the dielectric loss is reduced, thereby more effectively reducing the transmission loss.

[0119] Eighth Embodiment In the eighth embodiment, several examples of the structure of the signal line conductor layer 23 and the signal line conductor layer support portion 12S that are different from the examples shown so far will be described.

[0120] 15A, 15B, 15C, and 15D are all partial cross-sectional views of the transmission line according to the eighth embodiment.

[0121] 15A , the signal line conductor layer 23 is embedded in the insulator layer 13 by its thickness. An exposed surface ESB, which is a part of the first main surface S1 of the signal line conductor layer 23, protrudes from the signal line conductor layer support portion 12S and is exposed in the space 12H. With this structure, a part of the first main surface S1 of the signal line conductor layer 23 is in contact with the air in the space 12H and the side surfaces are covered by the insulator layer 13, and therefore the signal line conductor layer 23 is fixed by the insulator layer 13, resulting in high stability of the signal line conductor layer 23.

[0122] 15B, the signal line conductor layer 23 is formed on the lower surface of the insulator layer 13, and almost the entire side surface of the signal line conductor layer 23 is the exposed surface ESS. With this structure, the entire side surface of the signal line conductor layer 23 is in contact with the air in the space 12H, and the first main surface S1 is covered with the signal line conductor layer support portion 12S, so that deformation due to stress from above the transmission line is small.

[0123] 15(C) , the signal line conductor layer 23 is formed on the lower surface of the insulator layer 13, and the width of the signal line conductor layer 23 is greater than the width of the signal line conductor layer support portion 12S. With this structure, a portion of the first main surface S1 of the signal line conductor layer 23 protrudes from the signal line conductor layer support portion 12S, and the exposed surface ESB is exposed in the space 12H. Furthermore, the exposed surface ESS, which is almost the entire side surface of the signal line conductor layer 23, is exposed in the space 12H. With this structure, the entire side surface of the signal line conductor layer 23 and a portion of the first main surface S1 are in contact with the air in the space 12H, and therefore a wide area of ​​the portion with high electric field density is in contact with the air in the space 12H, resulting in a high effect of reducing dielectric loss.

[0124] 15(D) , the signal line conductor layer 23 is formed on the lower surface of the insulator layer 13, and one widthwise side of the signal line conductor layer 23 is exposed in the space 12H. That is, a part of the first main surface S1 protrudes from the signal line conductor layer support portion 12S, and an exposed surface ESB is exposed in the space 12H. In addition, an exposed surface ESS, which is almost the entire one side surface of the signal line conductor layer 23, is exposed in the space 12H. With this structure, there are portions where the signal line conductor layer support portion 12S is adhered to the insulator layer 13, resulting in strong adhesion between the insulator layers.

[0125] Ninth Embodiment In a ninth embodiment, several examples of the structure of the space 12H that are different from the examples shown so far will be described.

[0126] 16A , a space 12H is formed by sandwiching a tapered groove (opening) formed in the insulator layer 12 between the insulator layers 11 and 13. This makes it easy to process the insulator layer 12 from the top surface, and the signal line conductor layer support portion 12S at a location away from the signal line conductor layer 23 has a large width, thereby increasing the support strength of the signal line conductor layer 23 and ensuring a reduction in dielectric loss.

[0127] 16B, a space 12H is formed by sandwiching a tapered groove (opening) formed in the insulator layer 12 between the insulator layers 11 and 13. This allows the volume of the signal line conductor layer support portion 12S to be reduced, and the effect of reducing transmission loss due to the reduction in dielectric loss is high.

[0128] 16C , a non-penetrating recessed groove (opening) formed in the insulator layer 12 is sandwiched between the insulator layers 11 and 13, thereby forming the space 12H. This facilitates processing from the top surface of the insulator layer 12, and also prevents the main ground conductor layer 21 from being exposed to air, thereby preventing corrosion. Furthermore, the opening can be easily formed in the insulator layer 12 by wet etching.

[0129] 16(D), a groove (opening) with a cross section shaped like an hourglass is formed in the insulator layer 12 and sandwiched between the insulator layers 11 and 13, thereby forming the space 12H. This structure increases the area of ​​the portion in contact with the signal line conductor layer 23 and the reference ground conductor layer 21, thereby effectively reducing transmission loss due to dielectric loss. Even if the volume of the space 12H is large, the inner surface of the space 12H is a concave curved surface, which provides high stability in terms of strength of the transmission line. Furthermore, the opening can be easily formed in the insulator layer 12 by wet etching.

[0130] 16(E), a groove (opening) with a drum-shaped cross section formed in the insulator layer 12 is sandwiched between the insulator layers 11 and 13, thereby forming a space 12H. This structure increases the strength of the signal line conductor layer support portion 12S while maintaining the volume of air in the space 12H, thereby suppressing deformation of the transmission line due to external pressure on the transmission line.

[0131] Tenth Embodiment In a tenth embodiment, a transmission line having a hollow portion with a different shape from the examples shown so far will be illustrated.

[0132] 17(A), 17(B), 17(C), 17(D), 17(E), 17(F), 17(G), and 17(H) are plan views of the transmission line according to the tenth embodiment. These plan views are plan views of the first embodiment in the same state as that shown in FIG. 2(B). Note that, in consideration of the space in the drawings, directional symbols X, Y, and Z are only added to FIG. 17(H).

[0133] 2B and other examples, the hollow portion has a semi-cylindrical shape, but the present invention is not limited to this. The hollow portion may have any shape that includes a line segment along the plane of the insulating layer.

[0134] For example, in the example shown in Figure 17(A), the space 12H, which becomes a hollow space by laminating an insulating layer on the surface, has a triangular cylindrical shape. In the example shown in Figure 17(B), the space 12H has a trapezoidal cylindrical shape. As such, the shape of the space 12H can be selected from a variety of shapes depending on the processing method. Because the line segment is in contact with the signal line conductor layer 23, the signal line conductor layer 23 can be used to process the opening 13H, which improves the processability of the opening 13H.

[0135] 17C also has a trapezoidal cylindrical space 12H, but the space 12H reaches the side ground conductor layer 22. With this structure, the side ground conductor layer 22 can also be used to process the space 12H, and the width of the hollow space is determined by the position of the side ground conductor layer 22, thereby improving the dimensional accuracy of the hollow space.

[0136] In the example shown in Fig. 17(D), the space 12H has a rounded rectangular cylindrical shape, and in the example shown in Fig. 17(E), the space 12H has a semi-elliptical cylindrical shape or a semi-long cylindrical shape.

[0137] In the example shown in Fig. 17(F), the space 12H has a shape in which a plurality of semi-cylinders are stacked and connected. In the example shown in Fig. 17(G), the space 12H has a shape in which a plurality of semi-elliptical cylinders are stacked. With such a structure, the space 12H is a combination of cylinders, which makes it easy to process with a laser.

[0138] 17(H), the space 12H is triangular tubular, and its left-right positions relative to the extension direction of the signal line conductor layer 23 are alternately arranged along the extension direction of the signal line conductor layer 23. That is, the hollow spaces are arranged at a plurality of mutually separated positions at a predetermined pitch, and the positions of the hollow spaces are shifted in the extension direction by half or approximately half of the pitch on the left and right sides in the extension direction of the signal line conductor layer 23. With this structure, the volume ratio of the hollow spaces in the signal propagation direction of the transmission line is stable. This stabilizes the characteristic impedance of the transmission line in the signal propagation direction of the transmission line, thereby suppressing reflection loss.

[0139] In any of the transmission lines shown in Figures 17(A), 17(B), 17(C), 17(D), 17(E), 17(F), 17(G), and 17(H), when focusing on the length of the space portion 12H forming the hollow portion in the direction along the signal line conductor layer 23 (X direction), the length at a position away from the signal line conductor layer support portion (the lower portion of the signal line conductor layer 23 in the stacking direction) in the Y direction is shorter than the length at a position close to the signal line conductor layer support portion.

[0140] In any of the transmission lines shown in FIGS. 17(A), 17(B), 17(C), 17(E), 17(F), 17(G), and 17(H), the length of the space portion 12H forming the hollow portion in the direction along the signal line conductor layer 23 (X direction) becomes shorter as the distance from the signal line conductor layer support portion increases in the Y direction.

[0141] In the transmission line shown in FIG. 17D , the outer corners of the space 12H are rounded and the space 12H is a rectangular tube. Therefore, the length of the space 12H in the direction along the signal line conductor layer 23 (X direction) is constant up to a certain distance in the Y direction from the signal line conductor layer support portion, but becomes shorter at positions farther away.

[0142] 1(A), 17(A), 17(B), 17(C), 17(D), 17(E), 17(F), 17(G), and 17(H), the shape of the space 12H can be generally expressed as follows: "The space 12H has a portion that is shorter in dimension at a position farther from the signal line conductor layer supporting portion 12S in the extension direction (Y direction) of the signal line conductor layer supporting portion 12S than at a position close to the signal line conductor layer supporting portion 12S."

[0143] Eleventh Embodiment In an eleventh embodiment, a transmission line having a hollow portion with a different shape from the examples shown so far will be illustrated.

[0144] 18A, 18B, and 18C are plan views of a transmission line according to an eleventh embodiment, which are plan views of the first embodiment in the same state as that shown in FIG.

[0145] In the examples shown so far, a plurality of hollow portions are arranged in the extending direction of the signal line conductor layers, and these hollow portions have a continuous shape along the signal line conductor layers.

[0146] In the example shown in Figure 18 (A), the planar shape of the space portion 12H, which becomes a hollow portion by further laminating an insulating layer on the surface, is continuous along the signal line conductor layer 23 and has an overall elongated semi-elliptical shape.

[0147] In the example shown in FIG. 18B, the planar shape of the space 12H is a shape in which a plurality of semicircular shapes are overlapped, and the space 12H is continuous along the signal line conductor layer 23.

[0148] According to this structure, the space 12H is a combination of circles, which makes it easy to process with a laser.

[0149] 18C , the planar shape of the space 12H is trapezoidal and continues along the signal line conductor layer 23. With this structure, the side ground conductor layer 22 can also be used to process the space 12H, and the width of the hollow portion is determined by the position of the side ground conductor layer 22, thereby improving the dimensional accuracy of the hollow portion.

[0150] In any of the transmission lines shown in Figures 18(A), 18(B), and 18(C), when focusing on the length of the space portion 12H forming the hollow portion in the direction along the signal line conductor layer 23 (X direction), the length at a position away from the signal line conductor layer support portion (the lower portion of the signal line conductor layer 23 in the stacking direction) in the Y direction is shorter than the length at a position close to the signal line conductor layer support portion.

[0151] Twelfth Embodiment In a twelfth embodiment, a transmission line in which the shape of the signal line conductor layer is different from the examples shown so far will be illustrated.

[0152] 19A, both widthwise ends of the signal line conductor layer 23 are bent toward the reference ground conductor layer 21, and the entire lower surface of the signal line conductor layer 23 is in contact with the signal line conductor layer support portion 12S. This structure can increase the exposed area of ​​the signal line conductor layer 23 in the space 12H while maintaining the holding effect of the signal line conductor layer 23, thereby reducing transmission loss.

[0153] 19B, both widthwise ends of the signal line conductor layer 23 are bent toward the reference ground conductor layer 21, and these bent portions protrude from the signal line conductor layer support portion 12S and are exposed in the space 12H. This structure can further reduce transmission loss.

[0154] 19C , the cross-sectional shape of the signal line conductor layer 23 is arc-shaped, as is the insulator layer 13. Accordingly, the upper part of the space 12H is recessed toward the reference ground conductor layer 21. With this structure, even if another object (metal or dielectric) comes into contact with or is close to the upper side of the transmission line (the opposite side from the reference ground conductor layer 21), air gaps are formed between both ends of the signal line conductor layer 23 in the width direction and the other object, and therefore, the electrical characteristics of the transmission line are little affected by the contact or proximity.

[0155] 19D , the cross-sectional shape of the reference ground conductor layer 21 and the insulator layer 11 at the bottom of the space 12H is an arc that is significantly recessed toward the space 12H. Furthermore, the portion of the reference ground conductor layer 21 directly below the signal line conductor layer 23 is recessed toward the signal line conductor layer 23 from the reference line RL. With this structure, the entire reference ground conductor layer 21 and the insulator layer 11 are wavy, thereby increasing the rigidity of the entire transmission line. Furthermore, the narrow gap between the signal line conductor layer 23 and the reference ground conductor layer 21 directly below it prevents the electric field generated around the signal line conductor layer 23 from spreading to the opposite side of the reference ground conductor layer 21. Furthermore, the reference ground conductor layer 21 is partially adjacent to both sides of the signal line conductor layer 23, preventing the electric field generated around the signal line conductor layer 23 from spreading to the opposite side of the reference ground conductor layer 21. These features make it possible to suppress unnecessary interference between this transmission line and external objects or external circuits that are close to the signal line conductor layer 23 .

[0156] In a thirteenth embodiment, a transmission line in which the reference ground conductor layer, the side ground conductor layer, and the signal line conductor layer have different surface roughnesses on both sides is illustrated, and the positional relationship of the surface roughnesses of the conductor layers is also illustrated.

[0157] Fig. 20(A) is a plan view showing the insulating layer on which the conductor layer is formed before lamination. Fig. 20(B) is a cross-sectional view of the transmission line according to the thirteenth embodiment during its manufacture. Fig. 20(C) is a cross-sectional view of the transmission line 108 according to the thirteenth embodiment. Both Fig. 20(B) and Fig. 20(C) are cross-sectional views taken along the line Y2-Y2 shown in Fig. 20(A).

[0158] In the thirteenth embodiment, the transmission line 108 includes three insulator layers 11, 12, and 13. A reference ground conductor layer 21 is formed on the top surface of the insulator layer 11, a side ground conductor layer 22 is formed on the top surface of the insulator layer 12, and a signal line conductor layer 23 is formed on the bottom surface of the insulator layer 13.

[0159] The configurations of the signal line conductor layer support portion 12S, the space portion 12H, the opening portion 13H, and the interlayer connection conductor 4 are the same as those shown in the first embodiment.

[0160] Figure 21 is a cross-sectional view taken along line Y2-Y2 in Figure 20(A). Each conductor layer has different surface roughness between one side and the opposite side. In Figure 21, a surface with a relatively rough surface is shown as having a number of simple, fine, rectangular protrusions scattered across it (as if they were lined up in a cross section).

[0161] The surfaces of the main ground conductor layer 21 and the signal line conductor layer support portion 12S facing each other have small surface roughness (glossy surfaces). The surfaces of the side ground conductor layers 22 that do not face the main ground conductor layer 21 also have small surface roughness (glossy surfaces). This structure effectively reduces high-frequency signal transmission loss due to the skin resistance of the signal line conductor layers.

[0162] The surface of the main ground conductor layer 21 bonded to the insulator layer 11 is a roughened surface with a large surface roughness, the surface of the side ground conductor layer 22 bonded to the insulator layer 11 is a roughened surface with a large surface roughness, and the surface of the signal line conductor layer support portion 12S bonded to the insulator layer 13 is a roughened surface with a large surface roughness. This ensures strong adhesion between the main ground conductor layer 21 and the insulator layer 11. Similarly, the side ground conductor layer 22 ensures strong adhesion between the insulator layer 12. Furthermore, the top surfaces (glossy surfaces) of the main ground conductor layer 21 and the side ground conductor layer 22 have a certain degree of roughness. This ensures strong adhesion between the main ground conductor layer 21 and the insulator layer 12. Similarly, the side ground conductor layer 22 ensures strong adhesion between the insulator layer 13.

[0163] Fourteenth Embodiment In a fourteenth embodiment, a transmission line in which the space 12H is provided as a through-hole will be exemplified.

[0164] Fig. 22 is a plan view of the transmission line 109 according to the fourteenth embodiment. Figs. 23A, 23B, and 23C are cross-sectional views of the transmission line 109 and its manufacturing process. All of these are cross-sectional views taken along the line Y2-Y2 in Fig. 22.

[0165] The bonded structure between the insulator layer 11 and the reference ground conductor layer 21 is formed by bonding Cu foil to the upper surface of the insulator layer 11 and then patterning the Cu foil. The bonded structure between the insulator layer 12 and the side ground conductor layer 22 and the signal line conductor layer 23 is formed by bonding Cu foil to the upper surface of the insulator layer 12 and then patterning the Cu foil.

[0166] The insulator layer 11 to which the reference ground conductor layer 21 shown in FIG. 23A is bonded, the insulator layer 12 to which the side ground conductor layer 22 and the signal line conductor layer 23 are bonded, and the insulator layer 13 are stacked and bonded together to form a bonded body as shown in FIG. 23B.

[0167] Thereafter, a space 12H is formed in the bonded body, thereby forming the transmission line 109 shown in FIG. 23(C).

[0168] As shown in the fourteenth embodiment, the space 12H may be formed by a through-hole that penetrates the laminate.

[0169] As illustrated in the fourteenth embodiment, when the space 12H in contact with the signal line conductor layer 23 is configured to penetrate the insulator layers 11, 12, and 13, the region of high electric field strength around the signal line conductor layer 23 is a region without an insulator layer, and therefore, the dielectric loss reduction effect is high.

[0170] Fifteenth Embodiment In a fifteenth embodiment, a transmission line having a stripline structure will be illustrated. In addition, in the fifteenth embodiment, a transmission line having a different structure of the space portion from the examples shown so far will be illustrated.

[0171] Fig. 24 is a plan view of each layer showing the configuration of a transmission line according to the fifteenth embodiment. Fig. 25 is a cross-sectional view of a transmission line 115 formed by laminating the layers shown in Fig. 24. The cross-sectional position is the position indicated by Y2-Y2 in Fig. 24.

[0172] 24, the insulator layers and the conductor layers are shown separately. In FIG. 24, the reference ground conductor layer 21B and the mounting electrodes 24 are formed by patterning Cu foil attached to the lower surface of the insulator layer 13. The side ground conductor layers 22 and the signal line conductor layers 23 are formed by patterning Cu foil attached to the upper surface of the insulator layer 12A. 21A denotes Cu foil attached to the upper surface of the insulator layer 11.

[0173] The insulating layer 12A has a plurality of semicircular spaces 12H formed therein when viewed in the Z direction. A continuous region sandwiched between the semicircular spaces 12H forms the signal line conductor layer support portion 12S.

[0174] The insulating layer 12B has a plurality of circular spaces 12H formed therein when viewed in the Z direction.

[0175] The main ground conductor layer 21B and the side ground conductor layer 22 are connected via a plurality of interlayer connection conductors 4 that pass through the insulator layer 12B. The main ground conductor layer 21A and the side ground conductor layer 22 are connected via a plurality of interlayer connection conductors 4 that pass through the insulator layer 12A. The mounting electrode 24 is connected to the end of the signal line conductor layer 23 via an interlayer connection conductor that passes through the insulator layer 12B.

[0176] 25 , the signal line conductor layer 23 is disposed between the reference ground conductor layers 21A and 21B. The signal line conductor layer 23, the reference ground conductor layers 21A and 21B, and the dielectric between them form a stripline. The sides of the signal line conductor layer 23 are shielded by the side ground conductor layers 22.

[0177] The signal line conductor layer 23 is supported by the signal line conductor layer support portion 12S. In the cross-sectional view shown in FIG. 25 , the periphery of the signal line conductor layer 23, except for the signal line conductor layer support portion 12S, is a space 12H. The outer shape of the space 12H formed in the insulator layer 12A is the same as or substantially the same as the outer shape of the space 12H formed in the insulator layer 12B. With this configuration, the first main surface of the signal line conductor layer 23 is covered by the signal line conductor layer support portion 12S, while the second main surface of the signal line conductor layer 23, the side surface of the signal line conductor layer 23, and the side portion of the signal line conductor layer support portion 12S are exposed in the space 12H.

[0178] According to the fifteenth embodiment, the transmission line has a stripline structure in which the reference ground conductor layer 21B exists above the signal line conductor layer 23, and therefore has high shielding properties. In other words, the transmission line is less susceptible to the influence of adjacent objects and is less likely to affect adjacent objects.

[0179] Sixteenth Embodiment In a sixteenth embodiment, a transmission line having a hollow portion with a different shape from the examples shown so far will be exemplified.

[0180] The upper part of Fig. 26 is a partially enlarged plan view of the transmission line according to the sixteenth embodiment, which corresponds to the portion shown in Fig. 4 in the first embodiment.

[0181] In the transmission line according to the first embodiment, the shapes of the spaces 12H constituting the hollow portion were each semi-cylindrical. However, in the sixteenth embodiment, although the general shape of the spaces 12H is semi-cylindrical, in detail, the shape in the vicinity of the signal line conductor layer is distinctive.

[0182] 26, X1-X1 and X2-X2 are both line segments in the extension direction of the signal line conductor layer support portion 12S. The position of the line segment X1-X1 is near the signal line conductor layer support portion 12S, and the position of the line segment X2-X2 is far from the signal line conductor layer support portion 12S.

[0183] The dimension of the space 12H along the line segment X1-X1 is 12Hy1, and the dimension of the space 12H along the line segment X2-X2 is 12Hy2, where 12Hy2<12Hy1. However, the maximum dimension of the space 12H in the extension direction of the signal line conductor layer support portion 12S is greater than 12Hy1.

[0184] Even if the space portion 12H has such a shape, the space portion 12H has a portion that is shorter in dimension at a position farther away from the signal line conductor layer support portion 12S in the extension direction (X direction) of the signal line conductor layer support portion 12S than at a position close to the signal line conductor layer support portion 12S.

[0185] Seventeenth Embodiment In the seventeenth embodiment, a transmission line having a distinctive supporting structure for a signal line conductor layer will be exemplified.

[0186] FIG. 27(A) is a cross-sectional view of a transmission line 117A according to the seventeenth embodiment, FIG. 27(B) is a cross-sectional view of a transmission line 117B according to the seventeenth embodiment, and FIG. 27(C) is a cross-sectional view of a transmission line 117C according to the seventeenth embodiment.

[0187] 27(A), 27(B), and 27(C) are all cross-sectional views taken along a line passing through the space 12H.

[0188] 27A includes insulator layers 11, 12A, 12B, and 13, a signal line conductor layer 23, and a space 12H. The main ground conductor layer 21A is formed on the top surface of the insulator layer 11. The signal line conductor layer 23 is formed on the top surface of a signal line conductor layer support portion 12S, which is part of the insulator layer 12A. The main ground conductor layer 21B is formed on the bottom surface of the insulator layer 13.

[0189] The insulator layer 12A has a plurality of spaces 12H arranged along the extension direction (X direction) of the signal line conductor layer 23. For example, similar to the examples shown in Figures 1(A) and 3(B), the spaces 12H are semi-cylindrical spaces. These spaces 12H are arranged on both sides of the signal line conductor layer 23 when viewed in the stacking direction (Z direction) of the laminate.

[0190] The signal line conductor layer 23 has a first main surface S1 and a second main surface S2 that are opposite to each other, and a side surface that connects between the first main surface S1 and the second main surface S2. The side surfaces are both end surfaces of the signal line conductor layer 23 in the line width direction (Y direction).

[0191] In the transmission line 117A, in the region where the space 12H is formed, the first main surface S1 of the signal line conductor layer 23 faces the signal line conductor layer support portion 12S, and the second main surface S2 of the signal line conductor layer 23 is in contact with the insulator layer 12B. The side surface of the signal line conductor layer 23 is exposed in the space 12H.

[0192] Similar to the transmission line 117A, in the region where the space 12H is formed, the transmission line 117B has a first main surface S1 of the signal line conductor layer 23 facing the signal line conductor layer support portion 12S, and a second main surface S2 of the signal line conductor layer 23 in contact with the insulator layer 12B. In the transmission line 117B, the space 12H penetrates the insulator layers 12A and 12B, and therefore the space 12H expands in the stacking direction of the insulator layers (Z direction). The rest of the configuration is the same as that of the transmission line 117A.

[0193] The transmission line 117C includes insulator layers 11, 12A, 12B, 12C, and 13, a signal line conductor layer 23, and a space 12H. The reference ground conductor layer 21A is formed on the upper surface of the insulator layer 11. The signal line conductor layer 23 is formed on the upper surface of a signal line conductor layer support portion 12S, which is part of the insulator layer 12A. The reference ground conductor layer 21B is formed on the upper surface of the insulator layer 12. A plurality of spaces 12H are formed in the insulator layers 12A and 12B and are arranged along the extension direction (X direction) of the signal line conductor layer 23.

[0194] In the transmission line 117C, in the region where the space 12H is formed, the first main surface S1 of the signal line conductor layer 23 faces the signal line conductor layer support portion 12S, and the second main surface S2 of the signal line conductor layer 23 is in contact with the insulator layer 12B. The other configurations are similar to those of the transmission lines 117A and 117B.

[0195] In the transmission lines 117A, 117B, and 117C, a plurality of spaces 12H are arranged along the extension direction (X direction) of the signal line conductor layer 23, but these spaces 12H may be continuous along the extension direction (X direction) of the signal line conductor layer 23.

[0196] 27(A), 27(B), and 27(C) are all cross-sectional views, and therefore, at these cross-sectional positions, there are areas where the second main surface S2 of the signal line conductor layer 23 is in contact with a single insulator layer, but the second main surface S2 of the signal line conductor layer 23 may be in contact with multiple insulator layers.

[0197] Eighteenth Embodiment In an eighteenth embodiment, an electronic device according to the present invention will be illustrated.

[0198] 28 is a cross-sectional view of an electronic device 401 according to the eighteenth embodiment. The electronic device 401 includes substrates 201A and 201B, a battery 202, a transmission line 101, a housing 203, and the like.

[0199] A mounting component 9 serving as a connector is mounted on transmission line 101. This connector is connected to substrates 201A and 201B, respectively. A battery 202 is disposed between substrates 201A and 201B, and transmission line 101 is disposed between the outer surface of battery 202 and the inner surface of housing 203. An electronic circuit connected to transmission line 101 is configured on substrates 201A and 201B.

[0200] The positional relationship between the transmission line 101 and nearby objects such as the battery 202 and the housing 203 is important. That is, it is preferable to determine the orientation of the transmission line 101 so that the amount of change in electrical characteristics relative to the amount of change in the proximity distance of the object is small. For example, when comparing the side of the housing 203 made of metal with the side of the battery 202 containing a large amount of conductive material, if the transmission line 101 is more strongly affected by the housing 203, it is better to orient the reference ground conductor layer 21 ( FIG. 1 ) toward the housing 203. Furthermore, to reduce the influence of the battery 202, it is even more preferable to provide a gap between the signal line conductor layer 23 ( FIG. 1 ) of the transmission line 101 and the battery 202.

[0201] In the example shown in FIG. 28, the substrates 201A and 201B are connected to both ends of the transmission line via connectors, but it is also possible to use a structure in which one end of the transmission line is connected to the antenna.

[0202] The transmission line 101 transmits a high-frequency signal between the circuit configured on the substrate 201A and the circuit configured on the substrate 201B. This high-frequency signal is, for example, a signal in the 1 GHz to 1 THz band.

[0203] Various embodiments of the present invention have been presented so far, but these are all examples and are not intended to limit the scope of the present invention. Various omissions, substitutions, and modifications can be made to the embodiments of the present invention without departing from the spirit of the invention. Embodiments with such omissions, substitutions, and modifications are included within the scope and spirit of the present invention, and are also included in the scope of the invention and its equivalents as set forth in the claims of this application.

[0204] For example, the present invention can be applied to a simple (basic) microstrip line without the side ground conductor layer 22 .

[0205] Furthermore, the interlayer connection conductor 4 that electrically connects the main ground conductor layer 21 and the side ground conductor layer 22 may be formed by filling the resin-removed portion with conductive paste or solder paste and heating it, in addition to the electroplating method.

[0206] 6A, 6B, and 6C show examples in which the mounted component 9 is provided as a connector on the transmission line, but the mounted component is not limited to a connector. For example, it may be a semiconductor element or a circuit element.

[0207] In the example shown in FIG. 24, both ends of transmission line 101 are connected to substrates 201A and 201B via connectors, but it is also possible to adopt a structure in which the transmission line is directly connected to the substrate (mother substrate), that is, a structure in which the transmission line is mounted on the substrate.

[0208] Although the above embodiments have been described with reference to a transmission line having a single signal line conductor layer, the present invention can also be applied to a transmission line having multiple signal line conductor layers running in parallel. For example, a transmission line for transmitting differential signals may be configured by running two signal line conductor layers in parallel.

[0209] Furthermore, a plurality of signal line conductor layers may be arranged in one space, or a plurality of sets may be provided in which one signal line conductor layer has spaces 12H arranged on both sides thereof.

[0210] Furthermore, lines other than the transmission line of the present invention may be arranged within the same substrate made up of the insulating layers 11, 12, 13, etc.

[0211] Furthermore, a plurality of transmission lines may be arranged across the reference ground electrode in the stacking direction of the insulator layers such as the insulator layers 11, 12, and 13. In other words, a plurality of transmission lines may be arranged in the stacking direction.

[0212] Furthermore, a protective film such as a coverlay or a solder resist may be further formed on the surface of the insulating layer 11 or the insulating layer 13 .

[0213] The signal line conductor layer may have a shape that is curved in the plane direction of the insulating layers 11, 12, and 13.

[0214] The entire transmission line may also have a curved shape in the lamination direction (thickness direction) of the insulating layers 11, 12, 13, etc.

[0215] In addition, in each embodiment, an example has been shown in which the electrode connected to the signal line conductor layer is exposed upward, but the electrode connected to the signal line conductor layer 23 may be exposed on the underside of the laminate via an interlayer connecting conductor.

[0216] Furthermore, the signal propagating through the transmission line may be an analog signal or a digital signal.

[0217] In addition, in each embodiment, an example has been shown in which the space 12H is formed in the insulator layer to form the space 12H. The space 12H may be formed by processing the insulator layer, or the insulator layer may be formed with openings during the insulator layer formation stage. For example, a porous insulator layer may be formed, and some of the pores may be used as the space. Furthermore, a porous insulator layer with a higher porosity may be used near the signal line conductor layer by providing a distribution of the porosity ratio.

[0218] 1, 2, 3, etc., show examples in which the width of the signal line conductor layer support portion 12S is equal to the line width of the signal line conductor layer 23. However, the width of the signal line conductor layer support portion 12S may be wider than the line width of the signal line conductor layer 23. Although the dielectric loss is reduced more when the space 12H is closer to the signal line conductor layer support portion 12S, the dielectric loss reduction effect can be achieved even if the width of the signal line conductor layer support portion 12S is wider than the line width of the signal line conductor layer 23. In other words, a structure in which the signal line conductor layer 23 is not exposed in the space 12H is also possible.

[0219] The transmission line and electronic device of the present invention may be provided in the following aspects.

[0220] <1> A laminate is configured including a plurality of stacked insulator layers and conductor layers formed by being bonded to surfaces of all or some of the insulator layers of the plurality of insulator layers, wherein the conductor layers include a reference ground conductor layer and a signal line conductor layer overlapping the reference ground conductor layer when the laminate is viewed in the stacking direction, wherein an insulator layer between the signal line conductor layer and the reference ground conductor layer among the plurality of insulator layers serves as a signal line conductor layer support portion that supports the signal line conductor layer by being in contact with the signal line conductor layer along the signal line conductor layer, wherein a single or multiple space portions are present in a single or multiple insulator layers between the signal line conductor layer and the reference ground conductor layer among the plurality of insulator layers, wherein the space portion has a portion that is shorter at a distant position in a dimension in an extension direction of the signal line conductor layer support portion than at a nearby position, and wherein the signal line conductor layer has a first main surface and a second main surface that constitute opposite surfaces to each other, and a side surface that is connected between the first main surface and the second main surface, a first main surface of the signal line conductor layer facing the signal line conductor layer support portion, the signal line conductor layer having an exposed surface exposed to the space portion, and at least a part of the side surface, or at least a part of the first main surface, or at least a part of the side surface and at least a part of the first main surface is the exposed surface.

[0221] <2> The transmission line according to <1>, wherein the exposed surface includes a part of the first main surface of the signal line conductor layer and at least a part of the side surface of the signal line conductor layer, and a width of the first main surface is larger than a width of the signal line conductor layer support portion in a line width direction of the signal line conductor layer.

[0222] <3> The transmission line according to <1> or <2>, wherein the shape of the single space or the plurality of spaces has line segments along planes of the plurality of insulator layers, and the line segments are arranged at positions along the signal line conductor layers.

[0223] <4> The transmission line according to any one of <1> to <3>, wherein the single space or the plurality of spaces are arranged in a direction in which the signal line conductor layer extends.

[0224] <5> The transmission line according to <4>, wherein the single space or the plurality of spaces have a semi-cylindrical shape or a shape formed by combining substantially semi-cylindrical shapes.

[0225] <6> The transmission line according to <4> or <5>, wherein the single or the plurality of spaces are arranged at a predetermined arrangement pitch in a plurality of positions separated from each other, and the positions of the single or the plurality of spaces are shifted in the extension direction by half or approximately half of the arrangement pitch on the left and right sides in the extension direction of the signal line conductor layer.

[0226] <7> The transmission line according to any one of <1> to <6>, wherein the plurality of insulator layers have no path through which gas passes between the single space or the plurality of spaces and the outside of the laminate.

[0227] <8> The transmission line according to any one of <1> to <7>, wherein the material of the plurality of insulator layers is a thermoplastic resin.

[0228] <9> The transmission line according to any one of <1> to <7>, wherein the plurality of insulator layers are stacked with a material different from that of the plurality of insulator layers interposed therebetween.

[0229] <10> A laminate is configured including a plurality of stacked insulator layers and conductor layers formed by being bonded to surfaces of all or some of the insulator layers of the plurality of insulator layers, wherein the conductor layers include a reference ground conductor layer and a signal line conductor layer overlapping the reference ground conductor layer when the laminate is viewed in the stacking direction, wherein an insulator layer between the signal line conductor layer and the reference ground conductor layer among the plurality of insulator layers is a signal line conductor layer support portion that supports the signal line conductor layer by being in contact with the signal line conductor layer along the signal line conductor layer, wherein a single or multiple insulator layers between the signal line conductor layer and the reference ground conductor layer among the plurality of insulator layers have a single or multiple space portions, wherein the signal line conductor layer has a first main surface and a second main surface that constitute opposing surfaces, and a side surface that connects between the first main surface and the second main surface, wherein the first main surface of the signal line conductor layer faces the signal line conductor layer support portion, and wherein the signal line conductor layer has an exposed surface exposed in the space portion, a transmission line, wherein at least a portion of the side surface, or at least a portion of the first main surface, or at least a portion of the side surface and at least a portion of the first main surface is the exposed surface, and a second main surface of the signal line conductor layer is in contact with one or more of the plurality of insulator layers in the space portion.

[0230] <11> An electronic device comprising the transmission line according to any one of <1> to <10> and an electronic circuit connected to the transmission line.

[0231] EF...high electric field density portion ES, ESB, ESS...exposed surface RJ...contact portion S1...first main surface S2...second main surface SS...side surface 4...interlayer connection conductor 9...mounted component 9G...ground terminal 9S...signal terminal 11, 12, 12A, 12B, 13, 14...insulator layer 12H...space portion 12S...signal line conductor layer support portion 13H...opening 21, 21A, 21B...reference ground conductor layer 22, 22A, 22B...side ground conductor layer 22E...ground electrode 23...signal line conductor layer 23C...corner portion 23E...signal electrode 24...mounting electrode 51, 52...adhesive layer 101, 102, 103A, 103B, 104A, 104B, 105, 106A, 106B, 107, 108, 109, 115, 117A, 117B, 117C... transmission lines 201A, 201B... substrate 202... battery 203... housing 401... electronic device

Claims

1. A laminate is composed of a plurality of stacked insulator layers and conductor layers formed by bonding to surfaces of all or some of the insulator layers, the conductor layers including a reference ground conductor layer and a signal line conductor layer overlapping the reference ground conductor layer when the laminate is viewed in the stacking direction, an insulator layer between the signal line conductor layer and the reference ground conductor layer among the plurality of insulator layers constitutes a signal line conductor layer support portion that supports the signal line conductor layer by contacting along the signal line conductor layer, a single or multiple space portions are present in a single or multiple insulator layers between the signal line conductor layer and the reference ground conductor layer among the plurality of insulator layers, the space portion having a portion with a shorter dimension at a remote position in the extension direction of the signal line conductor layer support portion compared to a portion near the signal line conductor layer support portion, the signal line conductor layer has a first main surface and a second main surface that constitute opposite surfaces to each other, and a side surface connecting between the first main surface and the second main surface, a first main surface of the signal line conductor layer facing the signal line conductor layer support portion, the signal line conductor layer having an exposed surface exposed to the space portion, and at least a part of the side surface, or at least a part of the first main surface, or at least a part of the side surface and at least a part of the first main surface is the exposed surface.

2. The transmission line according to claim 1, wherein the exposed surface includes a portion of the first main surface of the signal line conductor layer and at least a portion of the side surface of the signal line conductor layer, and the width of the first main surface in the line width direction of the signal line conductor layer is greater than the width of the signal line conductor layer support portion.

3. A transmission line according to claim 1 or 2, wherein the shape of the single space or the plurality of spaces has line segments that run along the planes of the plurality of insulating layers, and the line segments are arranged at positions that run along the signal line conductor layers.

4. The transmission line according to any one of claims 1 to 3, wherein the single space or the multiple spaces are arranged in a direction in which the signal line conductor layer extends.

5. The transmission line according to claim 4, wherein the single space or the plurality of spaces have a shape of a semi-cylindrical or a combination of approximately semi-cylindrical shapes.

6. A transmission line according to claim 4 or 5, wherein the single or multiple spaces are arranged at multiple positions separated from one another at a predetermined arrangement pitch, and the positions of the single or multiple spaces are shifted in the extension direction by half or approximately half of the arrangement pitch on the left and right sides in the extension direction of the signal line conductor layer.

7. A transmission line according to any one of claims 1 to 6, wherein the plurality of insulating layers have no path through which gas passes between the single or plurality of spaces and the outside of the laminate.

8. The transmission line according to any one of claims 1 to 7, wherein the material of the plurality of insulating layers is a thermoplastic resin.

9. A transmission line according to any one of claims 1 to 7, wherein the plurality of insulating layers are laminated with a material different from that of the plurality of insulating layers interposed therebetween.

10. A laminate is formed comprising a plurality of stacked insulator layers and conductor layers formed by bonding to surfaces of all or some of the insulator layers of the plurality of insulator layers, the conductor layers including a reference ground conductor layer and a signal line conductor layer overlapping the reference ground conductor layer when the laminate is viewed in the stacking direction, an insulator layer between the signal line conductor layer and the reference ground conductor layer among the plurality of insulator layers is a signal line conductor layer support portion that supports the signal line conductor layer by contacting along the signal line conductor layer, a single or multiple space portions are present in a single or multiple insulator layers between the signal line conductor layer and the reference ground conductor layer among the plurality of insulator layers, the signal line conductor layer has a first main surface and a second main surface that constitute opposing surfaces, and a side surface connected between the first main surface and the second main surface, the first main surface of the signal line conductor layer faces the signal line conductor layer support portion, and the signal line conductor layer has an exposed surface exposed in the space portion, a transmission line, wherein at least a portion of the side surface, or at least a portion of the first main surface, or at least a portion of the side surface and at least a portion of the first main surface is the exposed surface, and a second main surface of the signal line conductor layer is in contact with one or more of the plurality of insulator layers in the space portion.

11. An electronic device comprising the transmission line according to any one of claims 1 to 10 and an electronic circuit connected to the transmission line.

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