High-frequency signal transmission line and electronic device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Filing Date
- 2024-11-07
- Publication Date
- 2026-06-10
Abstract
Description
High-frequency signal transmission lines and electronic devices
[0001] The present invention relates to a high-frequency signal transmission line and an electronic device including the same.
[0002] Patent Document 1 discloses a transmission line with a suspended structure in which a signal line is formed in a resin layer and hollow portions are formed above and below the signal line, and the side of the adhesive layer in contact with the hollow portion is configured to have a concave shape.
[0003] International Publication No. 2022 / 113591
[0004] In the high-frequency signal transmission line described in Patent Document 1, the adhesive layers are in contact only with the top and bottom surfaces of the base layer, so the laminate has a weak adhesive strength when it has a structure that forms a hollow portion. Furthermore, because there are no adhesive layers above or below the hollow portion, the strength of the layers above and below the hollow portion is weak. Therefore, when an external force acting on the high-frequency signal transmission line deforms the vicinity of the hollow portion of the high-frequency signal transmission line, the electrical characteristics of the high-frequency signal transmission line become unstable.
[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a high-frequency signal transmission line that maintains high strength in the resin laminated portion and the hollow portion and has stable electrical characteristics, and an electronic device equipped with the same.
[0006] An example of a high-frequency signal transmission line disclosed herein comprises: a resin laminate portion in which one or more first resin layers and one or more second resin layers are laminated; a signal conductor pattern arranged to be in contact with at least one first resin layer of the one or more first resin layers; and a ground conductor layer facing the signal conductor pattern across part or all of the resin laminate portion; wherein an opening is formed in at least one of the first resin layers of the resin laminate portion at a position along the signal conductor pattern, thereby providing a hollow portion in the resin laminate portion at the opening; and the second resin layer in contact with the first resin layer in which the opening is formed is bonded to a part of an end face of the opening in the first resin layer in which the opening is formed.
[0007] According to the present invention, a high-frequency signal transmission line having high resistance to externally applied stress and stable electrical characteristics, and an electronic device including the same, can be obtained.
[0008] The upper part of FIG. 1 is a plan view of a high-frequency signal transmission line 101 according to the first embodiment, and the lower part of FIG. 1 is a vertical cross-sectional view taken along the dashed-dotted line in the upper part of FIG. 1. FIG. 2 is a plan view of a high-frequency signal transmission line 102 according to a second embodiment. The upper part of FIG. 3 is a vertical cross-sectional view taken along the dashed-dotted line A-A in FIG. 2, and the lower part of FIG. 3 is a vertical cross-sectional view taken along the dashed-dotted line B-B in FIG. 2. FIG. 4 is a plan view of each layer in the middle of a manufacturing process of the high-frequency signal transmission line 102. FIG. 5 is a cross-sectional view of a high-frequency signal transmission line 103 according to a third embodiment. FIG. 6 is a cross-sectional view of a high-frequency signal transmission line 104 according to a fourth embodiment. FIG. 7 is a cross-sectional view of a high-frequency signal transmission line 105 according to a fifth embodiment. FIG. 8 is a cross-sectional view of a high-frequency signal transmission line 106 according to a sixth embodiment. FIG. 9 is a cross-sectional view of a high-frequency signal transmission line 107 according to a seventh embodiment. The upper part of Fig. 10 is a plan view of a high-frequency signal transmission line 108 according to the eighth embodiment, and the lower part of Fig. 10 is a vertical cross-sectional view of the dashed-dotted line portion in the upper part of Fig. 10. The upper part of Fig. 11 is a plan view of a high-frequency signal transmission line 109 according to the ninth embodiment, and the lower part of Fig. 11 is a vertical cross-sectional view of the dashed-dotted line portion in the upper part of Fig. 11. Fig. 12 is a plan view of high-frequency signal transmission lines 110A and 110B according to the tenth embodiment. Fig. 13 is a plan view of the first resin layer 11 of four types of high-frequency signal transmission lines according to the eleventh embodiment. Fig. 14 is a plan view of the first resin layer 11 of two types of high-frequency signal transmission lines according to the eleventh embodiment. The upper part of Fig. 15 is a cross-sectional view of a high-frequency signal transmission line 112 according to the twelfth embodiment. The lower part of Fig. 15 is a cross-sectional view of the high-frequency signal transmission line 112 showing the electric field distribution due to electric force lines. Fig. 16 is a vertical cross-sectional view of a high-frequency signal transmission line 113A according to the thirteenth embodiment. Fig. 17 is a vertical cross-sectional view of a high-frequency signal transmission line 113B according to a thirteenth preferred embodiment of the present invention. Fig. 18 is a vertical cross-sectional view of a high-frequency signal transmission line 114 according to a fourteenth preferred embodiment of the present invention.
[0009] Hereinafter, several specific examples will be given with reference to the drawings to illustrate multiple embodiments for carrying out the present invention. The same reference numerals are used for the same parts in each drawing. For ease of explanation and understanding of the main points, the embodiments are shown divided into multiple embodiments for convenience of explanation, but partial substitution or combination of the configurations shown in different embodiments is possible. From the second embodiment onwards, a description 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.
[0010] First Embodiment In the first embodiment, an example of a microstrip line type high-frequency signal transmission line will be described.
[0011] The upper part of Fig. 1 is a plan view of a high-frequency signal transmission line 101 according to the first embodiment, and the lower part of Fig. 1 is a vertical cross-sectional view of the portion indicated by the dashed dotted line in the upper part of Fig. 1. Although Fig. 1 shows a single high-frequency signal transmission line 101, a large number of high-frequency signal transmission lines that are continuous in the planar direction are manufactured up to the final manufacturing process, and are then separated into individual high-frequency signal transmission lines in the final manufacturing process. This also applies to each of the following embodiments.
[0012] The high-frequency signal transmission line 101 includes a resin laminate portion 3 , a signal conductor pattern 4 , and a ground conductor layer 5 .
[0013] The resin laminated portion 3 is a portion where the first resin layers 11, 12, and 13 and the second resin layers 21 and 22 are laminated. The signal conductor pattern 4 is formed on the upper surface of the first resin layer 11. The ground conductor layer 5 is laminated on the upper surface of the first resin layer 13. That is, the signal conductor pattern 4 and the ground conductor layer 5 face each other with part of the resin laminated portion 3 sandwiched therebetween.
[0014] A circular opening is formed in the first resin layer 12 and the second resin layer 21. In terms of shape in the drawing, this opening is circular when viewed in the stacking direction of the first resin layers 11, 12, and 13 and the second resin layers 21 and 22.
[0015] In this way, an opening is formed in the first resin layer 12 of the resin laminate portion 3 at a position along the signal conductor pattern 4, and this opening provides a hollow portion HP in the resin laminate portion 3. In particular, in this embodiment, a hollow portion HP is formed in which the first resin layer 12 and the second resin layer 22 do not contact the signal conductor pattern 4.
[0016] In this invention, not limited to this embodiment, the term "stacking direction" does not refer to the direction of the stacking order of the layers during manufacturing, but rather refers to the direction of stacking of the layers in the state shown in the drawing.
[0017] 1, the high-frequency signal transmission line 101 has six hollow portions HP. That is, the signal conductor pattern 4 passes through the hollow portions HP at six locations. The high-frequency signal transmission line 101 functions as a microstrip line consisting of the signal conductor pattern 4, the ground conductor layer 5, a part of the resin laminate portion 3, and the hollow portions HP.
[0018] If the distance between adjacent hollow portions HP is less than 1 / 4 wavelength of the transmission signal, the periodic change in characteristic impedance caused by the change in relative dielectric constant around the signal conductor pattern 4 does not pose a problem.
[0019] As shown in the upper part of Figure 1, a signal conductor pattern terminal 4T, which is separated from the ground conductor layer 5, is formed on the upper surface of the resin laminate portion 3. The end of the signal conductor pattern 4 is connected to the signal conductor pattern terminal 4T via an interlayer connection conductor. A coaxial connector 61 is mounted on the upper signal conductor pattern terminal 4T, and a coaxial connector 62 is mounted on the lower signal conductor pattern terminal 4T. In this way, the high-frequency signal transmission line 101 is used as a transmission line with coaxial connectors on both ends. The coaxial connectors 61 and 62 in Figure 1 indicate their mounting positions.
[0020] The signal conductor pattern 4 and the ground conductor layer 5 are both made of, for example, copper foil. The first resin layers 11, 12, and 13 are made of, for example, polyimide, liquid crystal polymer, or epoxy resin. The second resin layers 21 and 22 are made of, for example, thermoplastic polyimide, fluorine-based resin, or polyolefin-based resin. Examples of polyolefin-based resins include styrene, polyethylene, and polypropylene. The second resin layers 21 and 22 act as adhesive layers that bond adjacent first resin layers of the first resin layers 11, 12, and 13 together.
[0021] The flexibility of the second resin layers 21 and 22 at room temperature is greater than the flexibility of the first resin layers 11, 12, and 13. Here, room temperature is, for example, 25° C. or room temperature.
[0022] For example, the Young's modulus of the second resin layers 21 and 22 is 1 MPa or less, and the Young's modulus of the first resin layers 11, 12, and 13 is 2 MPa or more.
[0023] It is also preferable that the second resin layers 21, 22 have high fluidity during processing. They may be fluid, bond part of the end face (inner end face) of the opening, and then harden. The second resin layers 21, 22 may be made of a prepreg material used for interlayer bonding, for example.
[0024] The second resin layer has a lower dielectric constant than the first resin layer. For example, the second resin layers 21 and 22 have a dielectric constant of 2.2 to 2.8, and the first resin layers 11, 12, and 13 have a dielectric constant of 2.8 to 4.0.
[0025] The dielectric loss tangent of the second resin layer is lower than that of the first resin layer. For example, the dielectric loss tangent of the second resin layers 21 and 22 is 0.0005 to 0.003, and the dielectric loss tangent of the first resin layers 11, 12, and 13 is 0.002 to 0.01.
[0026] It is to be noted that either the relative dielectric constant or the dielectric loss tangent may satisfy the above relationship.
[0027] The second resin layer 22 in contact with the first resin layer 12 in which the opening is formed has different maximum and minimum thicknesses at the opening formed in the first resin layer 12, so that the second resin layer 22 is adhered to a part of the end face (inner end face) of the opening in the first resin layer 12. In other words, the second resin layer 22 is adhered to a part of the end face (inner surface) of the opening in the first resin layer 12, forming an adhesive section SA.
[0028] In this embodiment, the portion of the second resin layer that forms part of the hollow portion (part of the second resin layer 22) has a curved surface that expands outward from the hollow portion HP near the center of the hollow portion HP compared to the periphery of the hollow portion HP. For example, when a, b, and c are half the diameters in the X-axis, Y-axis, and Z-axis directions, respectively, this curved surface has a length x 2 / a 2 +y 2 / b 2 +z 2 / c 2 = 1. In the cross section shown at the bottom of Figure 1, the surface forms an elliptical arc. If a = b = c, then the cross section of the surface is a circular arc.
[0029] The second resin layer 22 has a curved surface that expands outward from the hollow portion HP near the center compared to the periphery of the hollow portion HP, but the first resin layer 13 and the second resin layer 22 are bonded over their entire surfaces. In other words, the first resin layer 13 is not exposed to the hollow portion HP.
[0030] A portion FA shown in the lower part of FIG. 1 indicates an adhesive portion where the second resin layer 22 is adhered to the first resin layer 13 even though the film thickness of the second resin layer 22 is thinner than the adhesive portion SA.
[0031] According to this embodiment, the following advantageous effects are achieved.
[0032] (a) The second resin layer 22, which is an adhesive layer, also bonds the end face (inner surface) of the opening of the first resin layer 12, so that the adhesive strength between the second resin layer 22 and the first resin layer 12 is high. Therefore, the strength of the hollow portion HP is high, stress applied from the outside to the high-frequency signal transmission line 101 is alleviated, and damage such as peeling between the layers is prevented.
[0033] (b) The portion of the resin laminate 3 that forms part of the hollow portion HP has a curved surface that expands outward from the hollow portion HP near the center compared to the periphery of the hollow portion HP, resulting in a thicker air layer near the signal conductor pattern 4. As a result, both the dielectric loss tangent and the dielectric constant of the dielectric between the signal conductor pattern 4 and the ground conductor layer 5 are small, thereby reducing the dielectric loss of the high-frequency signal transmission line.
[0034] (c) The portion of the second resin layer, which is relatively flexible, that forms part of the hollow portion is not the first resin layer, which is relatively less flexible, but a curved surface that extends outward from the periphery of the hollow portion near the center of the hollow portion. Therefore, the stress applied to the high-frequency signal transmission line 101 from the outside is effectively alleviated by the second resin layer, and a decrease in strength due to the presence of the hollow portion HP is suppressed.
[0035] (d) If the relative permittivity of the second resin layer on the side closer to the signal conductor pattern 4 is lower than that of the first resin layer, the dielectric loss reduction effect is excellent. Similarly, if the dielectric loss tangent of the second resin layer on the side closer to the signal conductor pattern 4 is lower than that of the first resin layer, the dielectric loss reduction effect is excellent.
[0036] (e) The second resin layer 22 has a curved surface that expands outward from the hollow portion HP near the center compared to the periphery of the hollow portion HP, and the first resin layer 13 and the second resin layer 22 are bonded together over the entire surface, resulting in a high adhesive strength between the first resin layer 13 and the second resin layer 22. This increases the strength of the hollow portion HP, mitigates external stress applied to the high-frequency signal transmission line 101, and prevents breakage.
[0037] (f) While Fig. 1 shows a configuration in which the signal conductor pattern 4 is exposed within the hollow portion HP, the signal conductor pattern 4 may also be formed on the underside of the first resin layer 11 (the surface opposite to the surface on which the hollow portion HP is formed). In this case, it is easier to ensure a sufficient distance between the ground conductor layer 5 and the signal conductor pattern 4. Therefore, the line width of the signal conductor pattern can be increased to obtain a predetermined characteristic impedance, thereby reducing transmission loss.
[0038] Second Embodiment In a second embodiment, an example of a stripline-type high-frequency signal transmission line in which a hollow portion HP exists around a signal conductor pattern 4 will be described.
[0039] Fig. 2 is a plan view of the high-frequency signal transmission line 102 according to the second embodiment. The upper part of Fig. 3 is a vertical cross-sectional view taken along the dashed dotted line A-A in Fig. 2, and the lower part of Fig. 3 is a vertical cross-sectional view taken along the dashed dotted line B-B in Fig. 2.
[0040] The high-frequency signal transmission line 102 includes an upper resin laminate portion 31, a lower resin laminate portion 32, a signal conductor pattern 4, a first ground conductor layer 51, a second ground conductor layer 52, a ground conductor pattern 5C, and an interlayer connection conductor 5V.
[0041] The upper resin laminate portion 31 is a portion where the upper first resin layers 11, 12, 13 and the second resin layers 21, 22 are laminated. The lower resin laminate portion 32 is a portion where the lower first resin layer 13 and the lower second resin layer 22 are laminated. That is, the resin laminate portion is composed of the upper resin laminate portion 31 laminated in a first stacking direction SD1 of the stacking directions of the first resin layers and the second resin layers, and the lower resin laminate portion 32 configured in a second stacking direction SD2 that is the opposite direction to the first stacking direction SD1.
[0042] The signal conductor pattern 4 and the ground conductor pattern 5C are formed on the upper surface of the first resin layer 11. A first ground conductor layer 51 is laminated on the upper surface of the upper first resin layer 13. A second ground conductor layer 52 is laminated on the lower surface of the lower first resin layer 13. That is, the signal conductor pattern 4 faces the first ground conductor layer 51 and the second ground conductor layer 52, with the upper resin laminate part 31 and the lower resin laminate part 32 sandwiched therebetween.
[0043] 3, interlayer connection conductors 5V are formed in the upper resin laminate portion 31. These interlayer connection conductors 5V electrically connect the first ground conductor layer 51 and the ground conductor pattern 5C. In addition, interlayer connection conductors 5V are formed in the lower resin laminate portion 32. These interlayer connection conductors 5V electrically connect the second ground conductor layer 52 and the ground conductor pattern 5C.
[0044] Circular openings are formed in the first resin layers 11, 12 and the second resin layer 21. In terms of shape in the drawing, these openings are circular when viewed in the stacking direction of the first resin layers 11, 12, 13 and the second resin layers 21, 22.
[0045] In this way, an opening is formed in the first resin layer 12 of the upper resin laminate portion 31 at a position along the signal conductor pattern 4, and this opening provides a hollow portion HP around the signal conductor pattern 4. In particular, in this embodiment, a hollow portion HP is formed in which the first resin layers 11, 12 and the second resin layers 21, 22 do not contact the signal conductor pattern 4.
[0046] 2, the high-frequency signal transmission line 102 has six hollow portions HP. That is, the signal conductor pattern 4 passes through the hollow portions HP at six locations. The high-frequency signal transmission line 102 functions as a strip line consisting of the signal conductor pattern 4, the first ground conductor layer 51, the second ground conductor layer 52, the upper resin laminate portion 31, the lower resin laminate portion 32, and the hollow portions HP.
[0047] As in the example shown in the first embodiment, if the spacing between the hollow portions HP is less than 1 / 4 wavelength of the transmission signal, the periodic change in the characteristic impedance due to the change in the relative dielectric constant around the signal conductor pattern 4 does not pose a problem.
[0048] The signal conductor pattern 4, the first ground conductor layer 51, and the second ground conductor layer 52 are all made of, for example, copper foil. The first resin layers 11, 12, and 13 are made of, for example, polyimide, liquid crystal polymer, or epoxy resin. The second resin layers 21 and 22 are made of, for example, thermoplastic polyimide, fluorine-based resin, or polyolefin-based resin. Examples of polyolefin-based resins include styrene, polyethylene, and polypropylene. The second resin layers 21 and 22 act as adhesive layers that bond adjacent first resin layers of the first resin layers 11, 12, and 13 together.
[0049] The relationship in flexibility between the second resin layers 21, 22 and the first resin layers 11, 12, 13, the relationship in relative dielectric constant between the second resin layers 21, 22 and the first resin layers 11, 12, 13, and the relationship in dielectric tangent between the second resin layers 21, 22 and the first resin layers 11, 12, 13 are the same as the example shown in the first embodiment.
[0050] In the upper part of Figure 3, the part indicated by the dashed line at the top of the figure is an adhesive area SA where the upper second resin layer 22 is adhered to part of the end face (inner surface) of the opening of the first resin layer 12.
[0051] In the upper part of Figure 3, the portion FA indicated by the dashed line at the top of the figure indicates the adhesive portion where the upper second resin layer 22 is adhered to the upper first resin layer 13 even though the film thickness of the upper second resin layer 22 is thinner than the original thickness.
[0052] The portion indicated by the dashed line at the bottom of the figure is an adhesive portion SA where the lower second resin layer 22 is adhered to a part of the end face (inner surface) of the opening of the first resin layer 11 .
[0053] In the upper part of Figure 3, the portion FA indicated by the dashed line at the bottom of the figure indicates the adhesive portion where the film thickness of the lower second resin layer 22 is thinner than the original thickness, but is still adhered to the lower first resin layer 13.
[0054] FIG. 4 is a plan view of each layer during the manufacturing process of the high-frequency signal transmission line 102. As already shown, the high-frequency signal transmission line 102 includes, from top to bottom, the first resin layer 13, the second resin layer 22, the first resin layer 12, the second resin layer 21, the first resin layer 11, the second resin layer 22, and the first resin layer 13. Circular openings OH are formed in the first resin layers 11 and 12 and the second resin layer 21. When these resin layers are stacked and pressurized and heated, as shown in the upper part of FIG. 3 , the upper second resin layer 22 melts and extends to the end face (inner surface) of the opening in the first resin layer 12. Similarly, the lower second resin layer 22 melts and extends to the end face (inner surface) of the opening in the first resin layer 11. Furthermore, a hollow portion HP formed by the overlapping openings OH expands due to heating. That is, as the film thickness of the upper second resin layer 22 becomes thinner than the original thickness of the upper second resin layer 22, and as the film thickness of the lower second resin layer 22 becomes thinner than the original thickness of the lower second resin layer 22, the hollow portion HP expands in the stacking direction.
[0055] The interlayer connection conductor 5V shown in FIG. 3 is formed by forming an opening that exposes the ground conductor pattern 5C by laser processing on the outer surface of the laminate formed by laminating the above-mentioned resin layers, and then depositing a copper plating film in this opening.
[0056] This embodiment provides the same effects as those described in the first embodiment. In addition, this embodiment provides the following effects.
[0057] (a) Since the hollow portion HP extends to the lower portion of the signal conductor pattern 4, the dielectric loss of the high-frequency signal transmission line is reduced more effectively.
[0058] (b) When viewed in the stacking direction of each resin, the interlayer connection conductors 5V are arranged on both sides of the arrangement line of the hollow portions HP, and the midpoint of the arrangement pitch of the hollow portions HP coincides with the arrangement position of the interlayer connection conductors 5V, so that the strength of the laminate formed by the stacking of each resin layer is uniformly increased by the interlayer connection conductors 5V.
[0059] (c) Because the second resin layers 21 and 22 are more flexible than the first resin layers 11, 12, and 13, the second resin layers 21 and 22 can absorb the steps of the ground conductor pattern 5C and fit around the inner surface of the hollow portion HP in a stable shape. Incidentally, if the flexibility of each resin layer is equal (if the first resin layers 11, 12, and 13 and the second resin layers 21 and 22 are both soft), it would be difficult to maintain a stable shape of the hollow portion HP.
[0060] Third Embodiment In a third embodiment, a high-frequency signal transmission line in which the shape of the hollow portion HP is different from the examples shown in the first and second embodiments will be illustrated.
[0061] FIG. 5 is a cross-sectional view of a high-frequency signal transmission line 103 according to the third preferred embodiment.
[0062] This high-frequency signal transmission line 103 includes an upper resin laminate portion 31, a lower resin laminate portion 32, a signal conductor pattern 4, a first ground conductor layer 51, a second ground conductor layer 52, a ground conductor pattern 5C, and an interlayer connection conductor (for example, the interlayer connection conductor 5V shown in FIG. 3).
[0063] The upper resin laminate portion 31 is a portion where the upper first resin layers 11, 12, 13 and the lower second resin layers 21, 22 are laminated. The lower resin laminate portion 32 is a portion where the lower first resin layer 13 and the lower second resin layer 22 are laminated.
[0064] The signal conductor pattern 4 and the ground conductor pattern 5C are formed on the upper surface of the first resin layer 11. A first ground conductor layer 51 is laminated on the upper surface of the upper first resin layer 13. A second ground conductor layer 52 is laminated on the lower surface of the lower first resin layer 13. That is, the signal conductor pattern 4 faces the first ground conductor layer 51 and the second ground conductor layer 52, with the upper resin laminate part 31 and the lower resin laminate part 32 sandwiched therebetween.
[0065] Circular openings are formed in the first resin layers 11, 12 and the second resin layer 21. In terms of shape in the drawing, these openings are circular when viewed in the stacking direction of the first resin layers 11, 12, 13 and the second resin layers 21, 22.
[0066] An opening is formed in the first resin layers 11, 12 of the upper resin laminate portion 31 at a position along the signal conductor pattern 4, and this opening provides a hollow portion HP around the signal conductor pattern 4.
[0067] The upper second resin layer 22 in contact with the first resin layer 12 in which the opening is formed protrudes into the opening of the first resin layer 12, and the thickness T1 of the upper second resin layer 22 in the region of the opening of the first resin layer 12 is greater than the thickness T0 of the other region. Similarly, the lower second resin layer 22 in contact with the first resin layer 11 in which the opening is formed protrudes into the opening of the first resin layer 11, and the thickness T1 of the lower second resin layer 22 in the region of the opening of the first resin layer 11 is greater than the thickness T0 of the other region.
[0068] With the above-described structure, the upper second resin layer 22 is adhered to a part of the end face (inner end face) of the opening formed in the first resin layer 12. Similarly, the lower second resin layer 22 is adhered to a part of the end face (inner end face) of the opening formed in the first resin layer 11.
[0069] According to this embodiment, similar to the case of the high-frequency signal transmission line shown in the second embodiment, the adhesion strength between the upper second resin layer 22 and the first resin layer 12 and the adhesion strength between the lower second resin layer 22 and the first resin layer 11 are high. Therefore, the strength of the hollow portion HP is high, stress applied to the high-frequency signal transmission line 101 from the outside is alleviated, and damage is prevented. In addition, because the second resin layers 22 above and below the hollow portion HP are thick and flat, the strength of the hollow portion HP can be easily increased. The cross-sectional shape of this hollow portion HP can be changed depending on the flexibility of the second resin layer 22, etc.
[0070] Fourth Embodiment In a fourth embodiment, a high-frequency signal transmission line in which the hollow portion is relatively expanded compared to the embodiments shown so far will be exemplified.
[0071] FIG. 6 is a cross-sectional view of a high-frequency signal transmission line 104 according to the fourth preferred embodiment.
[0072] The high-frequency signal transmission line 104 includes an upper resin laminate portion 31, a lower resin laminate portion 32, a signal conductor pattern 4, a first ground conductor layer 51, a second ground conductor layer 52, and a ground conductor pattern 5C. As described in the second embodiment, the ground conductor pattern 5C is an intermediate layer ground conductor pattern that is electrically connected to the first ground conductor layer 51 and the second ground conductor layer 52 via interlayer connection conductors.
[0073] The difference from the high-frequency signal transmission line 102 shown in the upper part of Figure 3 is that there is a non-adhesive portion NA between the upper second resin layer 22 and the upper first resin layer 13, and there is a non-adhesive portion NA between the lower second resin layer 22 and the lower first resin layer 13.
[0074] According to this embodiment, the air layers above and below the signal conductor pattern 4 can be made thicker than in the high-frequency signal transmission line shown in the second embodiment, and dielectric loss can be reduced more effectively.
[0075] In the example shown in FIG. 6, the non-adhesive portions NA are formed on both the top and bottom of the signal conductor pattern 4, but the non-adhesive portions NA may be formed only on either the top or bottom.
[0076] The high-frequency signal transmission line 104 of this embodiment is manufactured by the following methods. In one method, when the upper second resin layer 22 is applied to the upper first resin layer 13, it is applied to the first resin layer 12 except for a position facing the opening. Similarly, when the lower second resin layer 22 is applied to the lower first resin layer 13, it is applied to the first resin layer 11 except for a position facing the opening. In another method, the upper second resin layer 22 is applied to the entire surface of the upper first resin layer 13, and then the first resin layer 12 is partially removed near a position facing the opening. Similarly, the lower second resin layer 22 is applied to the entire surface of the lower first resin layer 13, and then the first resin layer 11 is partially removed near a position facing the opening.
[0077] According to this embodiment, the height of the hollow portion HP can be easily increased.
[0078] Fifth Embodiment In a fifth embodiment, a high-frequency signal transmission line in which different second resin layers are connected to each other around a hollow portion will be described as an example.
[0079] FIG. 7 is a cross-sectional view of a high-frequency signal transmission line 105 according to the fifth preferred embodiment.
[0080] The high-frequency signal transmission line 105 includes an upper resin laminate portion 31, a lower resin laminate portion 32, a signal conductor pattern 4, a first ground conductor layer 51, a second ground conductor layer 52, and a ground conductor pattern 5C. As described in the second embodiment, the ground conductor pattern 5C is an intermediate layer ground conductor pattern that is electrically connected to the first ground conductor layer 51 and the second ground conductor layer 52 via interlayer connection conductors.
[0081] The high-frequency signal transmission line 102 differs from the high-frequency signal transmission line 102 shown in the upper part of FIG. 3 in the following two points.
[0082] (1) The upper second resin layer 22 and the upper second resin layer 21 are connected along the hollow portion HP.
[0083] (2) The second resin layer 21 and the upper second resin layer 22 are bonded to a part of the end face (inner surface) of the opening of the first resin layer 11 .
[0084] According to this embodiment, the second resin layer 21 and the upper second resin layer 22, which are adhesive layers, are bonded to the entire end face (inner surface) of the opening of the first resin layer 12 in the thickness direction, thereby increasing the adhesive strength between the second resin layers 21 and 22 and the first resin layer 12. This more effectively increases the strength of the hollow portion HP.
[0085] Sixth Embodiment In the sixth embodiment, an example of a suspended line type high-frequency signal transmission line is shown, in which a hollow portion HP exists above the signal conductor pattern 4 and another hollow portion HP exists below the first resin layer 11 on which the signal conductor pattern is formed.
[0086] FIG. 8 is a cross-sectional view of a high-frequency signal transmission line 106 according to the sixth preferred embodiment.
[0087] The high-frequency signal transmission line 106 includes an upper resin laminate portion 31, a lower resin laminate portion 32, a signal conductor pattern 4, a first ground conductor layer 51, a second ground conductor layer 52, and a ground conductor pattern 5C.
[0088] The upper resin laminate portion 31 is a portion where the upper first resin layers 11, 12, 13 and the second resin layers 21, 22 are laminated. The lower resin laminate portion 32 is a portion where the lower first resin layers 12, 13 and the lower second resin layers 22, 23 are laminated. That is, the resin laminate portion is composed of the upper resin laminate portion 31 laminated in a first stacking direction SD1 of the stacking directions of the first resin layers and the second resin layers, and the lower resin laminate portion 32 configured in a second stacking direction SD2 that is the opposite direction to the first stacking direction SD1.
[0089] The signal conductor pattern 4 and the ground conductor pattern 5C are formed on the upper surface of the first resin layer 11. A first ground conductor layer 51 is laminated on the upper surface of the upper first resin layer 13. Furthermore, a second ground conductor layer 52 is laminated on the lower surface of the lower first resin layer 13.
[0090] Circular openings are formed in the upper first resin layer 12 and the upper second resin layer 21. Circular openings are also formed in the lower first resin layer 12 and the lower second resin layer 22.
[0091] The other structures are the same as those of the high-frequency signal transmission line shown in the second embodiment.
[0092] According to this embodiment, the presence of the first resin layer 11 that continuously supports the signal conductor traces 4 makes it possible to easily increase the strength of the signal conductor traces 4 .
[0093] Seventh Embodiment In the seventh embodiment, an example of a high-frequency signal transmission line will be described in which the shape of the hollow portions HP formed above and below the signal conductor pattern 4 is different from that of the example shown in the sixth embodiment.
[0094] FIG. 9 is a cross-sectional view of a high-frequency signal transmission line 107 according to the seventh preferred embodiment.
[0095] The high-frequency signal transmission line 107 includes an upper resin laminate portion 31, a lower resin laminate portion 32, a signal conductor pattern 4, a first ground conductor layer 51, a second ground conductor layer 52, and a ground conductor pattern 5C.
[0096] The other structures are the same as those of the high-frequency signal transmission line shown in the sixth embodiment.
[0097] The high-frequency signal transmission line 106 shown in FIG. 8 differs from the high-frequency signal transmission line 106 in the following respects.
[0098] (1) The second resin layer 21, which is an adhesive layer on the upper side of the first resin layer 11 on which the signal conductor pattern 4 is formed, also adheres to a part of the end face (inner surface) of the opening of the upper first resin layer 12. The upper adhesive portion SA in Figure 9 indicates this portion.
[0099] (2) The second resin layers 22 and 23, which are adhesive layers below the first resin layer 11 on which the signal conductor pattern 4 is formed, also adhere to a portion of the end face (inner surface) of the opening of the lower first resin layer 12. The lower adhesive portion SA in Figure 9 indicates this portion.
[0100] According to this embodiment, the side surfaces of other first resin layers adjacent to the first resin layer on which the signal conductor pattern 4 is formed are also bonded with the second resin layer, so that the strength of the hollow portion HP is high, stress applied to the high-frequency signal transmission line 107 from the outside is alleviated, and damage is prevented.
[0101] Eighth Embodiment In the eighth embodiment, a high-frequency signal transmission line in which a hollow portion is formed in the extending direction of the signal conductor pattern 4 will be exemplified.
[0102] The upper part of FIG. 10 is a plan view of the high-frequency signal transmission line 108 according to the eighth embodiment, and the lower part of FIG. 10 is a vertical cross-sectional view of the portion enclosed by the dashed dotted line in the upper part of FIG.
[0103] The high-frequency signal transmission line 108 includes an upper resin laminate portion 31, a lower resin laminate portion 32, a signal conductor pattern 4, a first ground conductor layer 51, a second ground conductor layer 52, a ground conductor pattern 5C, and an interlayer connection conductor 5V.
[0104] The upper resin laminate portion 31 is a portion where the upper first resin layers 11, 12, 13 and the lower second resin layers 21, 22 are laminated. The lower resin laminate portion 32 is a portion where the lower first resin layer 13 and the lower second resin layer 22 are laminated.
[0105] The signal conductor pattern 4 and the ground conductor pattern 5C are formed on the upper surface of the first resin layer 11. A first ground conductor layer 51 is laminated on the upper surface of the upper first resin layer 13. A second ground conductor layer 52 is laminated on the lower surface of the lower first resin layer 13. That is, the signal conductor pattern 4 faces the first ground conductor layer 51 and the second ground conductor layer 52, with the upper resin laminate part 31 and the lower resin laminate part 32 sandwiched therebetween.
[0106] Interlayer connection conductors 5V are formed in the upper resin laminate portion 31. These interlayer connection conductors 5V electrically connect the first ground conductor layer 51 and the ground conductor pattern 5C. In addition, interlayer connection conductors 5V are formed in the lower resin laminate portion 32. These interlayer connection conductors 5V electrically connect the second ground conductor layer 52 and the ground conductor pattern 5C.
[0107] 10, the high-frequency signal transmission line 10 does not have multiple hollow portions HP as shown in the upper part of Fig. 1, for example, but has a continuous hollow portion HP along the extension direction of the signal conductor pattern 4. The high-frequency signal transmission line 108 functions as a strip line consisting of the signal conductor pattern 4, the first ground conductor layer 51, the second ground conductor layer 52, the first resin layer, the second resin layer, and the hollow portion HP.
[0108] According to this embodiment, since the hollow portion HP is formed only in the upper resin layer, it is easy to maintain high mechanical strength of the signal conductor pattern 4 even if stress is applied to the vicinity of the hollow portion HP due to an external force on the high-frequency signal transmission line 108. Furthermore, since the hollow portion HP is not dispersed in the signal propagation direction, no periodic change in the characteristic impedance occurs.
[0109] Ninth Embodiment In a ninth embodiment, a high-frequency signal transmission line will be illustrated in which the positional relationship between the hollow portion and the interlayer connection conductor and the structure of the interlayer connection conductor are different from those of the examples shown so far.
[0110] The upper part of FIG. 11 is a plan view of the high-frequency signal transmission line 109 according to the ninth embodiment, and the lower part of FIG. 11 is a vertical cross-sectional view of the portion enclosed by the dashed dotted line in the upper part of FIG.
[0111] The high-frequency signal transmission line 109 includes an upper resin laminate portion 31, a lower resin laminate portion 32, a signal conductor pattern 4, a first ground conductor layer 51, a second ground conductor layer 52, a ground conductor pattern 5C, and an interlayer connection conductor 5V.
[0112] In the high-frequency signal transmission line 102 shown in the lower part of FIG. 3 , the interlayer connection conductor 5V is formed by forming a conductor plating film on the inner surface of an opening formed in each resin layer between the first ground conductor layer 51 and the ground conductor pattern 5C, and similarly, the interlayer connection conductor 5V is formed by forming a conductor plating film on the inner surface of an opening formed in each resin layer between the second ground conductor layer 52 and the ground conductor pattern 5C. However, in the high-frequency signal transmission line 109 shown in FIG. 11 , the interlayer connection conductor 5V is formed by filling with a conductor the opening formed in each resin layer between the first ground conductor layer 51 and the ground conductor pattern 5C, and the interlayer connection conductor 5V is formed by filling with a conductor the opening formed in each resin layer between the second ground conductor layer 52 and the ground conductor pattern 5C.
[0113] 2 shows an example in which the interlayer connection conductors 5V are arranged on both sides of the arrangement line of the hollow portions HP when viewed in the lamination direction of the resins, and the midpoint of the arrangement pitch of the hollow portions HP coincides with the arrangement position of the interlayer connection conductors 5V. In contrast, in the high-frequency signal transmission line 109 shown in FIG. 11, the interlayer connection conductors 5V are arranged on both sides of the hollow portions HP when viewed in the lamination direction of the resins.
[0114] According to this embodiment, the interlayer connection conductors 5V are present in positions close to each hollow portion HP, and the strength of the hollow portion HP is effectively increased by the interlayer connection conductors 5V. That is, when viewed in the stacking direction of the resin layers, the interlayer connection conductors 5V that are close to the hollow portion HP are positioned so as to straddle the hollow portion HP, and therefore the interlayer connection conductors 5V are located in positions close to the hollow portion HP. As a result, the strength of the hollow portion HP is effectively increased by the interlayer connection conductors 5V.
[0115] Furthermore, since the interlayer connection conductor 5V protrudes from the surface and is positioned to span the hollow portion, even if an object comes into contact with it from the outside (even if it comes into contact with an external object), the object will hit the protruding portion of the interlayer connection conductor 5V, preventing it from hitting the top or bottom of the hollow portion HP, thereby suppressing deformation of the hollow portion HP.
[0116] The structure in which the interlayer connection conductors 5V adjacent to the hollow portions HP are positioned to straddle the hollow portions HP is also satisfied in the example shown in Fig. 2. That is, in Fig. 2, the interlayer connection conductors 5V adjacent to the hollow portions HP straddle the hollow portions HP on a line inclined at 45 degrees with respect to the arrangement direction of the hollow portions HP.
[0117] Tenth Embodiment In a tenth embodiment, a high-frequency signal transmission line will be illustrated in which the positional relationship between the hollow portion and the interlayer connection conductor and the structure of the interlayer connection conductor are different from those of the examples shown so far.
[0118] 12 is a plan view of high-frequency signal transmission lines 110A and 110B according to the tenth embodiment. Each of the high-frequency signal transmission lines 110A and 110B includes a first ground conductor layer 51, a ground conductor pattern 51C, a signal conductor pattern terminal 4T, multiple hollow portions HP, and multiple interlayer connection conductors 5V. The internal structure is the same as that shown in the second embodiment. The second ground conductor layer 52 overlaps with the first ground conductor layer 51 in the plan view.
[0119] The high-frequency signal transmission line 110A and the high-frequency signal transmission line 110B differ in the arrangement of the interlayer connection conductors 5V. Both the high-frequency signal transmission lines 110A and 110B have fewer interlayer connection conductors than the examples shown in FIGS.
[0120] In the high-frequency signal transmission line 110A, adjacent interlayer connection conductors 5V sandwiching a hollow portion HP in a plan view pass through (straddle) the same hollow portion HP.
[0121] In the high-frequency signal transmission line 110B, adjacent interlayer connection conductors 5V sandwiching a hollow portion HP in a plan view pass through (straddle) the two hollow portions HP.
[0122] Even if the number of such interlayer connection conductors 5V is small, if adjacent interlayer connection conductors 5V are positioned so as to sandwich the hollow portion HP in a plan view and pass through (straddle) the hollow portion HP, the interlayer connection conductors 5V will highly reinforce the hollow portion HP, thereby alleviating the stress applied to the high-frequency signal transmission lines 110A, 110B from the outside and preventing damage.
[0123] Eleventh Embodiment In an eleventh embodiment, a high-frequency signal transmission line will be illustrated in which the shape and arrangement pitch of the hollow portions are different from those of the examples shown so far.
[0124] Fig. 13(1) is a plan view of the first resin layer 11 of an example high-frequency signal transmission line. For example, it is a plan view of the first resin layer 11 of the high-frequency signal transmission line 102 shown in the second embodiment. Fig. 13(2) and (3) are plan views of the first resin layer 11 (the first resin layer on which the signal conductor pattern 4 is formed) of a high-frequency signal transmission line that differs from the example of (1) in the shape of the hollow portions and their arrangement pitch. Fig. 13(4) is a plan view of the first resin layer 11 of a high-frequency signal transmission line that differs in the line width of the signal conductor pattern in the hollow portions and other portions.
[0125] 13(1), a plurality of circular openings OH are formed in the first resin layer 11. The width of these openings OH is AW, and the spacing between the openings OH is GS. Here, the larger the value of AW / GS, the higher the rate at which the signal conductor pattern 4 passes through the hollow portion, thereby reducing the dielectric loss due to the relative permittivity and dielectric dissipation factor of the resin layer. However, if the value of AW / GS becomes extremely large, the strength of the hollow portion formed by the openings OH becomes lower than the specified value, which may cause damage near the hollow portion.
[0126] In particular, when the gap GS is small, the value of AW / GS may become extremely large due to the shortening of the gap GS caused by stacking misalignment during manufacturing.
[0127] In the example shown in Figure 13 (2), oval-shaped openings OH are formed in the first resin layer 11. The width of these openings OH is AW, and the spacing between the openings OH is GS. As such, even if the shape of the openings OH has an aspect ratio, the larger the value of AW / GS, the higher the rate at which the signal conductor pattern 4 passes through the hollow portion, thereby reducing dielectric loss due to the relative permittivity and dielectric dissipation factor of the resin layer. However, because the major axis of the openings OH is aligned with the extension direction of the signal conductor pattern 4, the efficiency of lengthening the openings OH relative to the expansion of their planar area is high. Therefore, even without an extremely large value of AW / GS, dielectric loss can be effectively reduced, and the strength of the hollow portion formed by the openings OH can be maintained, reducing the risk of damage near the hollow portion.
[0128] In this way, by elongating the opening OH, the gap GS can be increased, thereby maintaining the strength of the hollow portion. For example, if AW = 4 mm and GS = 1 mm in the example shown in the upper part of Fig. 13, the effect of providing a hollow portion by the opening OH can be equalized by setting AW = 7 mm and GS = 1.75 mm in the example shown in the middle part of Fig. 13.
[0129] In the example shown in Figure 13 (3), openings OH are formed in the first resin layer 11 in the shape of two overlapping circles offset by a certain distance in the extension direction of the signal conductor pattern 4. The width of these openings OH in the extension direction of the signal conductor pattern 4 is AW, and the spacing between the openings OH is GS. Even in the case of such an opening OH shape, the major axis of the opening OH is aligned with the extension direction of the signal conductor pattern 4, so the efficiency of lengthening the opening OH relative to the expansion of its planar area is high. Moreover, compared to the example shown in Figure 13 (2), the efficiency of lengthening the opening OH relative to the expansion of its planar area is higher. Therefore, the rate of expansion of the planar area associated with an increase in the value of AW / GS is suppressed. This maintains the strength of the hollow portion formed by the opening OH, further reducing the risk of damage near the hollow portion.
[0130] 13(4), the line width of the signal conductor pattern 4 differs between the portion laminated on the second resin layer (the second resin layer 21 shown in FIG. 3) and the portion not in contact with the second resin layer. The line width of the signal conductor pattern 4 not in contact with the second resin layer is wider than the line width of the signal conductor pattern 4 laminated on the second resin layer. This structure makes it possible to align the relative permittivity between the signal conductor pattern 4 and the first ground layer (the first ground conductor layer 51 shown in FIG. 3) and the second ground conductor layer (the second ground conductor layer 52 shown in FIG. 3), thereby suppressing unwanted reflections due to mismatches in characteristic impedance in high-frequency signals.
[0131] The upper part of Fig. 14 is a plan view of the first resin layer 11 of an example high-frequency signal transmission line. The lower part of Fig. 14 is a plan view of the first resin layer 11 (the first resin layer on which the signal conductor pattern 4 is formed) of a high-frequency signal transmission line whose hollow portion shape and arrangement pitch are different from those of the upper example.
[0132] 14, a plurality of diamond-shaped openings OH, each with rounded corners, are formed in the first resin layer 11. The width of these openings OH in the extension direction of the signal conductor pattern 4 is AW, and the spacing between the openings OH in the extension direction of the signal conductor pattern 4 is GS. As described above, the larger the value of AW / GS, the higher the rate at which the signal conductor pattern 4 passes through the hollow portion, thereby reducing the dielectric loss due to the relative permittivity and dielectric loss tangent of the resin layer.
[0133] Comparing the example shown in the upper part of Figure 14 with the example shown in the upper part of Figure 13, even if the value of AW / GS is the same, the planar area and volume of the opening OH can be made smaller, which improves the effect of maintaining the strength of the hollow part created by the opening OH and further reducing the risk of breakage near the hollow part.
[0134] 14 (lower part), openings OH having a shape in which three diamonds are overlapped and shifted by a certain distance in the extension direction of the signal conductor pattern 4 are formed in the first resin layer 11. The width of these openings OH in the extension direction of the signal conductor pattern 4 is AW, and the spacing between the openings OH is GS. In the case of openings OH having such a shape, as in the example shown in FIG. 13 (3), the major axis of the openings OH is aligned with the extension direction of the signal conductor pattern 4, and therefore the efficiency of lengthening the openings OH relative to the expansion of the planar area of the openings OH is high.
[0135] Twelfth Embodiment In a twelfth embodiment, a high-frequency signal transmission line in which the top and bottom of a resin laminate are recessed will be exemplified.
[0136] The upper part of Fig. 15 is a cross-sectional view of the high-frequency signal transmission line 112 according to this embodiment. The lower part of Fig. 15 is a cross-sectional view of the high-frequency signal transmission line 112, showing the electric field distribution caused by electric field lines. This high-frequency signal transmission line 112 includes an upper resin laminate portion 31, a lower resin laminate portion 32, a signal conductor pattern 4, a first ground conductor layer 51, a second ground conductor layer 52, and a ground conductor pattern 5C. The other basic structure is similar to that of the high-frequency signal transmission line 109 shown in Fig. 11 .
[0137] 3 , the high-frequency signal transmission line 112 of this embodiment has recesses RA formed at the top and bottom of the hollow portion HP in the resin lamination direction. During manufacturing, the high-frequency signal transmission line 112 is formed with the recesses RA by pressing the first ground conductor layer 51 attached to the first resin layer 13.
[0138] The high-frequency signal transmission line 112 of this embodiment has the following advantages.
[0139] (a) It is difficult for any object to come into contact with the vicinity of the hollow portion HP from outside the high-frequency signal transmission line 112, and this makes it possible to prevent deformation of the hollow portion HP and its surroundings.
[0140] (b) Since the resin layer in the vicinity of the hollow portion HP has an arch-shaped cross section, deformation of the hollow portion HP and its surroundings can be effectively suppressed.
[0141] Needless to say, in this embodiment as well, as shown in FIG. 3, there may be interlayer connection conductors that protrude to the outside of the resin laminate.
[0142] In the high-frequency signal transmission line 112 of this embodiment, the arrows protruding from the signal conductor pattern 4 at the bottom of Fig. 15 are noteworthy electric field lines. In this manner, an electric field is generated between the signal conductor pattern 4 and the first ground conductor layer 51, and between the signal conductor pattern 4 and the second ground conductor layer 52. As shown in this figure, the electric field lines from the signal conductor pattern 4 to the first ground conductor layer 51 and the second ground conductor layer 52 become longer as they approach both ends of the signal conductor pattern 4, i.e., as they move away from the center of the signal conductor pattern 4.
[0143] Although the current density of the signal conductor pattern 4 increases closer to both ends due to the edge effect (skin effect) of the conductor, the above-described configuration reduces the electric field strength closer to both ends of the signal conductor pattern 4, averaging the current distribution in the signal conductor pattern 4. As a result, the conductor loss due to the signal conductor pattern 4 is mitigated.
[0144] Thirteenth Embodiment In a thirteenth embodiment, a high-frequency signal transmission line having a protective film on its outer surface will be exemplified.
[0145] FIG. 16 is a vertical cross-sectional view of a high-frequency signal transmission line 113A formed by forming a resist film on the high-frequency signal transmission line 109 shown in FIG.
[0146] FIG. 17 is a vertical cross-sectional view of a high-frequency signal transmission line 113B formed by forming a resist film on the high-frequency signal transmission line 109 shown in FIG.
[0147] The resist film RF shown in FIGS. 16 and 17 is a resist film obtained by applying a resist resin to the front and back surfaces of the high-frequency signal transmission line 109 shown in FIG. 11 and then hardening it.
[0148] In this way, by providing the resist film RF on the outer surface, the stress applied to the high-frequency signal transmission lines 113A, 113B from the outside is alleviated by the resist film RF, and the reduction in strength of the high-frequency signal transmission lines due to the presence of the hollow portion HP is further suppressed.
[0149] In the high-frequency signal transmission line 113A shown in FIG. 16, even if some external object comes into contact with the line, the stress received by the resist film RF is concentrated on the interlayer connection conductor 5V, so that the hollow portion HP is protected.
[0150] As shown in Figure 17, if the resist film RF protrudes at the protruding portions of the interlayer connecting conductor 5V, the presence of these protruding portions makes it difficult for any object to come into contact with the vicinity of the hollow portion HP from outside the high-frequency signal transmission line 113B, thereby preventing deformation of the hollow portion HP and its surroundings.
[0151] Fourteenth Embodiment In a fourteenth embodiment, a high-frequency signal transmission line will be illustrated in which the structure of the upper and lower outer surfaces of the hollow portion is different from the examples shown so far.
[0152] 18 is a longitudinal cross-sectional view of a high-frequency signal transmission line 114 according to a fourteenth embodiment. In this example, when viewed in the stacking direction of the layers, the plating thickness of the first ground conductor layer 51 and the second ground conductor layer 52 is increased in regions that overlap the hollow portion HP to form thickened portions TF. The plating of these regions may be performed simultaneously with the plating for forming the interlayer connection conductors 5V.
[0153] According to this embodiment, the strength of the laminate above and below the hollow portion HP is effectively increased, which makes it possible to more effectively suppress deformation of the hollow portion HP.
[0154] Fifteenth Embodiment In the fifteenth embodiment, an electronic device will be exemplified.
[0155] The high-frequency signal transmission line of the present invention can be used as a high-frequency signal transmission line in various electronic devices. For example, connectors are provided on high-frequency circuits formed on two circuit boards, and coaxial connectors 61 and 62 of the high-frequency signal transmission line 101 shown in Figure 1 are connected to each other. The circuit boards and high-frequency signal transmission line 101 are housed in a housing of a predetermined shape. In this way, an electronic device is constructed.
[0156] Finally, the present invention is not limited to the above-described embodiments. Those skilled in the art can make appropriate modifications and variations. The scope of the present invention is defined not by the above-described embodiments but by the claims. Furthermore, the scope of the present invention includes modifications and variations from the embodiments within the scope of the claims and their equivalents.
[0157] For example, although the high-frequency signal transmission line has been shown in each embodiment to have a single signal conductor pattern, it may have a plurality of signal conductor patterns.
[0158] Furthermore, a differential line may be configured by including two or more signal conductor patterns, and the multiple signal conductor patterns that make up this differential line may be arranged in a single hollow space.
[0159] Furthermore, the signal conductor patterns may be arranged in the layer direction of each resin layer, or in the stacking direction of each resin layer.
[0160] In addition, in each embodiment, the high-frequency signal transmission line has a rectangular shape when viewed from the lamination direction of the resin layers, but this shape is arbitrary.
[0161] In addition, in each embodiment, a high-frequency signal transmission line having a linear signal conductor pattern is shown, but when viewed from the stacking direction of each resin layer, the signal conductor pattern may be curved or partially curved.
[0162] In addition, although the high-frequency signal transmission line has been illustrated as being planar in each embodiment, the lamination surface of each resin layer may be a curved surface such as a cylindrical surface, or a partially curved surface.Furthermore, for example, the entire surface or a portion thereof may be a twisted curved surface.
[0163] Furthermore, a resin layer different from the first resin layer and the second resin layer may be provided to bond the copper foil forming the ground conductor layer to the first resin layer.
[0164] The high-frequency signal transmission line and electronic device of the present invention may be provided in the following aspects.
[0165] <1> A high-frequency signal transmission line comprising: a resin laminate portion in which one or more first resin layers and one or more second resin layers are laminated; a signal conductor pattern arranged to be in contact with at least one first resin layer of the one or more first resin layers; and a ground conductor layer facing the signal conductor pattern with part or all of the resin laminate portion in between; wherein an opening is formed in at least one of the first resin layers of the resin laminate portion at a position along the signal conductor pattern, thereby providing a hollow portion in the resin laminate portion at the opening, and the second resin layer in contact with the first resin layer in which the opening is formed is bonded to a part of an end face of the first resin layer in which the opening is formed.
[0166] <2> The high-frequency signal transmission line according to <1>, wherein the ground conductor layer is composed of a first ground layer and a second ground conductor layer located on both sides of the signal conductor pattern in the stacking direction, and the first resin layer and the second resin layer are located on both sides of the signal conductor pattern in the stacking direction.
[0167] <3> The high-frequency signal transmission line according to <2>, further comprising an interlayer connection conductor that electrically connects the first ground conductor layer and the second ground conductor layer, wherein a transmission line is formed by the first ground conductor layer, the second ground conductor layer, the upper resin laminate portion, the lower resin laminate portion, the signal conductor pattern, and the interlayer connection conductor.
[0168] <4> The high-frequency signal transmission line according to <3>, wherein the interlayer connection conductor has a protruding portion that protrudes outward in the first stacking direction from the first ground conductor layer, and the interlayer connection conductor has a protruding portion that protrudes outward in the second stacking direction from the second ground conductor layer.
[0169] <5> The high-frequency signal transmission line according to <4>, further comprising a third resin layer that covers the protruding portion of the interlayer connection conductor on an outer surface of the upper resin laminate portion or the lower resin laminate portion.
[0170] <6> The high-frequency signal transmission line according to any one of <1> to <5>, wherein the second resin layer in contact with the first resin layer in which the opening is formed has a maximum thickness and a minimum thickness that are different at the opening formed in the first resin layer, so that the second resin layer in contact with the first resin layer is adhered to a part of an end face at the opening of the first resin layer in which the opening is formed.
[0171] <7> The high-frequency signal transmission line according to any one of <1> to <6>, wherein a portion of the second resin layer that forms part of the hollow portion has a curved surface that expands outward from the hollow portion near a center compared to a periphery of the hollow portion.
[0172] <8> The high-frequency signal transmission line according to any one of <1> to <7>, wherein the second resin layer has greater flexibility than the first resin layer at room temperature.
[0173] <9> The high-frequency signal transmission line according to any one of <1> to <8>, wherein the resin material of the second resin layer has a lower dielectric constant and a lower dielectric loss tangent than the resin material of the first resin layer.
[0174] <10> The high-frequency signal transmission line according to any one of <1> to <9>, wherein a part of the second resin layer is formed in an arch shape in the opening of the first resin layer.
[0175] <11> The high-frequency signal transmission line according to any one of <1> to <10>, wherein the second resin layer in contact with the first resin layer in which the opening is formed protrudes into the opening, and the thickness of the second resin layer is greater in the region of the opening than in other regions.
[0176] <12> The high-frequency signal transmission line according to any one of <1> to <11>, wherein the opening of the second resin layer is formed in the opening of the first resin layer, and the opening of the first resin layer and the opening of the second resin layer form the hollow portion.
[0177] <13> The high-frequency signal transmission line according to any one of <1> to <12>, wherein the hollow portion is formed over a width wider than the width of the signal conductor pattern.
[0178] <14> An electronic device comprising the high-frequency signal transmission line according to any one of <1> to <13>.
[0179] FA...adhesive portion GS...spacing HP...hollow portion NA...non-adhesive portion OH...opening RA...recess RF...resist film SA...adhesive portion SD1...first lamination direction SD2...second lamination direction TF...thickened portion T0...normal thickness T1...expanded thickness 3...resin laminated portion 4...signal conductor pattern 4T...signal conductor pattern terminal 5...ground conductor layer 5C...ground conductor pattern 5V...interlayer connecting conductor 10...high-frequency signal transmission line 11, 12, 13...first resin layer 21, 22, 23...second resin layer 31...upper resin laminated portion 32...lower resin laminated portion 51...first ground conductor layer 51C...ground conductor pattern 52...second ground conductor layer 61, 62...coaxial connectors 101 to 109...high-frequency signal transmission line 110A, 110B...high-frequency signal transmission line 112...high frequency signal transmission line 113A, 113B...high frequency signal transmission lines
Claims
1. The device comprises a resin laminate formed by laminating one or more first resin layers and one or more second resin layers, a signal conductor pattern arranged to be in contact with at least one of the first resin layers, and a ground conductor layer facing the signal conductor pattern with part or all of the resin laminate in between. In the resin laminate, an opening is formed in at least one of the first resin layers located along the signal conductor pattern, thereby providing a hollow portion in the resin laminate at the opening. The second resin layer in contact with the first resin layer in which the opening is formed is bonded to a part of the end face of the opening in the first resin layer. High-frequency signal transmission line.
2. The ground conductor layer is composed of a first ground conductor layer and a second ground conductor layer located on both sides of the signal conductor pattern in the direction of lamination. The resin laminate portion exists as an upper resin laminate portion and a lower resin laminate portion on both sides of the signal conductor pattern in the direction of lamination. The high-frequency signal transmission line according to claim 1.
3. The first ground conductor layer and the second ground conductor layer are electrically connected by interlayer connecting conductors, The transmission line is formed by the first ground conductor layer, the second ground conductor layer, the upper resin laminate, the lower resin laminate, the signal conductor pattern, and the interlayer connecting conductor. The high-frequency signal transmission line according to claim 2.
4. The interlayer connecting conductor has a protrusion that extends outward from the first ground conductor layer, and the interlayer connecting conductor has a protrusion that extends outward from the second ground conductor layer. The high-frequency signal transmission line according to claim 3.
5. The outer surface of the upper resin laminate or the lower resin laminate is provided with a third resin layer that covers the protruding portion of the interlayer connecting conductor. The high-frequency signal transmission line according to claim 4.
6. The second resin layer in contact with the first resin layer in which the opening is formed has a difference in maximum and minimum thickness at the opening in the first resin layer, so that the second resin layer in contact with the first resin layer adheres to a part of the end face at the opening in the first resin layer. A high-frequency signal transmission line according to any one of claims 1 to 5.
7. The portion of the second resin layer that forms part of the hollow section is a curved surface that extends outward from the hollow section near the center compared to the periphery of the hollow section. A high-frequency signal transmission line according to any one of claims 1 to 5.
8. At room temperature, the second resin layer has a higher Young's modulus than the first resin layer. A high-frequency signal transmission line according to any one of claims 1 to 5.
9. The resin material of the second resin layer has a lower dielectric constant and lower dielectric loss tangent compared to the resin material of the first resin layer. A high-frequency signal transmission line according to any one of claims 1 to 5.
10. In the opening of the first resin layer, a part of the second resin layer is formed in an arch shape. A high-frequency signal transmission line according to any one of claims 1 to 5.
11. The second resin layer, which is in contact with the first resin layer in which the opening is formed, protrudes into the opening, and the thickness of the second resin layer is thicker in the region of the opening than in other regions. A high-frequency signal transmission line according to any one of claims 1 to 5.
12. The opening of the first resin layer is formed in the opening of the second resin layer, and the opening of the first resin layer and the opening of the second resin layer form the hollow portion. A high-frequency signal transmission line according to any one of claims 1 to 5.
13. The hollow portion is formed over a wider area than the width of the signal conductor pattern. A high-frequency signal transmission line according to any one of claims 1 to 5.
14. An electronic device comprising a high-frequency signal transmission line according to any one of claims 1 to 5.