Differential transmission line and electronic apparatus

Abstract

A differential transmission line (101) comprises a laminate that is formed from a plurality of insulator layers (11–16) and a plurality of conductors that are provided along the insulator layers. A hollow (HS) is formed in the laminate. A first signal line (61) and a second signal line (62) that are two conductors are joined via an inter-signal-line insulator layer (73). The first signal line (61) and the second signal line (62) are offset in the layer direction. The inter-signal-line insulator layer (73) as seen in the layering direction is in at least a signal line overlap region (OR) in which the first signal line (61) and the second signal line (62) overlap; a signal line laminate that is formed from the inter-signal-line insulator layer (73), the first signal line (61), and the second signal line (62) is inside the hollow (HS); and a space (SD) is formed by the hollow (HS) outside the signal line overlap region (OR).

Description

Differential transmission line and electronic device

[0001] The present invention relates to a differential transmission line including a laminate formed by laminating a plurality of insulating layers and a plurality of conductors, and to an electronic device including the same.

[0002] Patent Document 1 discloses an electrical system in which a transmission line assembly is formed by a first conductive line and a second conductive line that are arranged opposite each other with a dielectric layer interposed therebetween, and the transmission line assembly is surrounded by a shielding conductor.

[0003] Furthermore, Patent Document 2 discloses a high-frequency semiconductor device in which a distributed coupled parallel line is configured by fixing a first central conductor and a second central conductor via a resin material that surrounds the outside of the first central conductor and the second central conductor.

[0004] Special table 2016-509391 publication JP 7-183708 publication

[0005] In the electrical system described in Patent Document 1, the first conductive line and the second conductive line face each other across their entire surfaces via a dielectric layer. Therefore, when the first conductive line and the second conductive line are used as the main part of a differential transmission line, the electrostatic capacitance between the first conductive line and the second conductive line becomes large. Therefore, in order to achieve a predetermined differential impedance in the high-frequency band of the differential transmission line, the spacing between the first conductive line and the second conductive line, i.e., the thickness, needs to be increased, making it difficult to make the product thinner.

[0006] In the high-frequency semiconductor device described in Patent Document 2, due to its structure, the dielectric constant between the first and second central conductors and the ground conductor is high, and if the signal line is made thinner to set the characteristic impedance to a predetermined value, the conductor loss and the dielectric loss also increase. Furthermore, because the first and second central conductors are formed on separate substrates, their positions are unstable, and misalignment causes variation in the capacitance between the first and second central conductors.

[0007] Therefore, an object of the present invention is to provide a differential transmission line that can suppress deterioration of electrical characteristics and / or reduce the size of the line portion, and an electronic device equipped with the same.

[0008] (1) A differential transmission line as an example of the present disclosure includes: a plurality of insulator layers and a plurality of conductors provided along the insulator layers; a laminate is formed by laminating the plurality of insulator layers and the plurality of conductors; openings are formed in predetermined insulator layers among the plurality of insulator layers, thereby forming a hollow portion by overlapping of the openings in the plurality of insulator layers; a first signal line and a second signal line are formed by at least two of the plurality of conductors; an inter-signal line insulator layer, which is at least one insulator layer among the plurality of insulator layers, is present between the first signal line and the second signal line; the first signal line and the second signal line are misaligned in a direction perpendicular to the longitudinal direction of the first signal line and the second signal line and in a layer direction which is a direction formed by the plurality of insulator layers and the layers of the plurality of conductors, when viewed in the lamination direction; The first signal line and the second signal line are spaced apart via the inter-signal line insulator layer, and a signal line laminate is formed by the first signal line, the second signal line, and the inter-signal line insulator layer, and the inter-signal line insulator layer is arranged in a signal line overlapping range, which is a range where the first signal line and the second signal line overlap when viewed in the stacking direction, and the signal line laminate is arranged within the hollow portion, and a space portion formed by the hollow portion is formed outside the signal line overlapping range.

[0009] (2) As an example of the present disclosure, an electronic device is configured by including the differential transmission line. For example, the electronic device is configured by connecting or mounting the differential transmission line to a separate substrate.

[0010] According to the present invention, a differential transmission line that can suppress deterioration of electrical characteristics and / or reduce the size of the line portion, and an electronic device including the same, can be obtained.

[0011] FIG. 1A is a cross-sectional view of a differential transmission line 101 according to a first embodiment, and FIG. 1B is a plan view of the differential transmission line 101. FIG. 2 is a cross-sectional view of the differential transmission line 101 in a state before lamination of multiple insulator layers and multiple conductors, which are components of the differential transmission line 101. FIG. 3A is a cross-sectional view of the differential transmission line 101, FIG. 3B is a plan view taken along the F2-F2 plane in FIG. 3A, and FIG. 3C is a plan view taken along the F1-F1 plane in FIG. 3A. FIG. 4 is a cross-sectional view of another differential transmission line 101A according to the first embodiment. FIG. 5A is a cross-sectional view of a differential transmission line 102 according to a second embodiment, FIG. 5B is a plan view taken along the F2-F2 plane in FIG. 5A, and FIG. 5C is a plan view taken along the F1-F1 plane in FIG. 5A. FIG. 6 is a cross-sectional view of a differential transmission line 103 according to a third embodiment. Fig. 7 is a cross-sectional view of a differential transmission line 104 according to a fourth embodiment. Fig. 8 is a cross-sectional view of a differential transmission line 105 according to a fifth embodiment. Fig. 9 is a cross-sectional view of a differential transmission line 106 according to a sixth embodiment. Fig. 108 is a cross-sectional view of a differential transmission line 107 according to a seventh embodiment. Fig. 11(A) is a cross-sectional view of an electronic device 508 according to an eighth embodiment. Fig. 11(B) is a plan view of the electronic device 508.

[0012] 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.

[0013] First Embodiment In a first embodiment, the overall configuration of a differential transmission line and the configuration of each part will be illustrated, and the effects of the structure will be described.

[0014] Fig. 1A is a cross-sectional view of a differential transmission line 101 according to the first embodiment, and Fig. 1B is a plan view of the differential transmission line 101. Fig. 1A is a cross-sectional view taken along the line X1-X1 in Fig. 1B. Fig. 2 is a cross-sectional view of the state before multiple insulator layers and multiple conductors are laminated.

[0015] 1A, 1B and 2, X, Y and Z represent the directions of three orthogonal axes, which also apply to the subsequent figures.

[0016] The differential transmission line 101 includes a plurality of insulator layers 11, 12, 13, 14, 15, and 16, an inter-signal line insulator layer 73, and a plurality of conductors provided along these insulator layers. A ground conductor layer 41 is located on the lower surface of the insulator layer 11. A ground conductor layer 46 is located on the upper surface of the insulator layer 16. Ground conductor layers 42, 43, 44, and 45 are located on the lower surfaces of the insulator layers 12, 13, 14, and 15, respectively.

[0017] The first signal line 61 is located on the lower surface of the inter-signal line insulator layer 73 , and the second signal line 62 is located on the lower surface of the insulator layer 14 and on the upper surface of the inter-signal line insulator layer 73 .

[0018] The ground conductor layers 41 and 46, the ground conductor layers 42, 43, 44, and 45, the first signal line 61, and the second signal line 62 correspond to the "conductors" according to the present invention. That is, the first signal line 61 and the second signal line 62 are formed by at least two conductors among the plurality of conductors.

[0019] A laminate is formed by laminating a plurality of insulator layers 11, 12, 13, 14, 15, and 16, an inter-signal line insulator layer 73, ground conductor layers 41 and 46, ground conductor layers 42, 43, 44, and 45, a first signal line 61, and a second signal line 62. Figures 1A and 1B show the laminated state.

[0020] The insulator layers 11, 12, 13, 14, 15, and 16 and the inter-signal line insulator layer 73 are sheets of, for example, liquid crystal polymer resin, polyimide resin, epoxy resin, fluorine resin, or polyolefin resin. By sandwiching a resin with a relatively low dielectric constant between the signal lines in this manner, the electrostatic capacitance generated between the first signal line 61 and the second signal line 62 can be effectively reduced, and deterioration of the characteristics of the differential transmission line can be effectively suppressed.

[0021] The ground conductor layers 41, 46, the ground conductor layers 42, 43, 44, and 45, the first signal line 61, and the second signal line 62 are made of, for example, copper, silver, or graphite foil, and are attached to one side of each resin layer before lamination to create a multilayer board. Because the first signal line 61 and the second signal line 62 are made of a conductive material with high conductivity, the conductor loss of the transmission line can be reduced. Furthermore, because the ground conductors are made of a conductive material with high conductivity, the shielding properties of the differential transmission line are improved. This effectively improves EMI (Electro Magnetic Interference), EMS (Electro Magnetic Susceptibility), and EMC (Electro Magnetic Compatibility).

[0022] 1 and 2 , among the multiple insulator layers 11, 12, 13, 14, 15, and 16, openings OS are formed in the insulator layers 12, 13, and 14, and a hollow portion HS is formed by overlapping of the openings OS of the insulator layers 12, 13, and 14. The inter-signal line insulator layer 73 is an insulator layer formed by providing an opening OS in the insulator layer 13.

[0023] An inter-signal line insulator layer 73 is present between the first signal line 61 and the second signal line 62. In this example, a single inter-signal line insulator layer is provided between the first signal line 61 and the second signal line 62, but the inter-signal line insulator layer 73 may be composed of multiple insulator layers.

[0024] When viewed in the stacking direction (Z direction), the first signal line 61 and the second signal line 62 are misaligned in a direction (X-Z plane direction) perpendicular to the longitudinal direction (Y direction) of the first signal line 61 and the second signal line 62 and in the layer direction (X direction) formed by the layers of the insulator layers 11, 12, 13, 14, 15, and 16 and the conductors (ground conductor layers 41 and 46, ground conductor layers 42, 43, 44, and 45, the first signal line 61, and the second signal line 62).

[0025] The first signal line 61 and the second signal line 62 are spaced apart via an inter-signal line insulator layer 73, and a signal line laminate is formed by the first signal line 61, the second signal line 62, and the inter-signal line insulator layer 73.

[0026] The inter-signal line insulator layer 73 is disposed at least within the signal line overlapping range OR, which is the range where the first signal line 61 and the second signal line 62 overlap, when viewed in the stacking direction (Z direction).

[0027] The signal line laminate including the first signal line 61, the second signal line 62, and the inter-signal line insulator layer 73 is disposed in the hollow portion HS. As a result, a space portion SD is formed by the hollow portion HS outside the signal line overlapping range OR.

[0028] The inter-signal line insulator layer 73 has a thickness of zero outside the signal line overlapping area. That is, the thickness of the inter-signal line insulator layer 73 outside the signal line overlapping area is thinner than the thickness within the signal line overlapping area OR. The above expression "a space portion SD is formed by the hollow portion HS outside the signal line overlapping area OR" can also be rephrased as "the thickness of the inter-signal line insulator layer 73 outside the signal line overlapping area is thinner than the thickness within the signal line overlapping area OR."

[0029] Among the plurality of conductors, the conductors located on the outer surface of the laminate constitute ground conductor layers 41 and 46 .

[0030] The ground conductor layers 41 and 46 are not limited to being located on the outer surface of the laminate, but may be located in the vicinity of the outer surface.

[0031] An interlayer connection conductor 51 that is electrically connected to the ground conductor layer 41 is formed inside the insulator layer 11. An interlayer connection conductor 56 that is electrically connected to the ground conductor layer 46 is formed inside the insulator layer 16. An interlayer connection conductor 52 that is electrically connected to the ground conductor layer 42 is formed inside the insulator layer 12. An interlayer connection conductor 53 that is electrically connected to the ground conductor layer 43 is formed inside the insulator layer 13. Similarly, an interlayer connection conductor 54 that is electrically connected to the ground conductor layer 44 is formed inside the insulator layer 14, and an interlayer connection conductor 55 that is electrically connected to the ground conductor layer 45 is formed inside the insulator layer 15.

[0032] In addition, in the state of the laminate, the interlayer connection conductor 51 provides electrical continuity between the ground conductor layer 41 and the ground conductor layer 42, and the interlayer connection conductors 55 and 56 provide electrical continuity between the ground conductor layer 46 and the ground conductor layer 45. In addition, the interlayer connection conductor 52 provides electrical continuity between the ground conductor layer 42 and the ground conductor layer 43, the interlayer connection conductor 53 provides electrical continuity between the ground conductor layer 43 and the ground conductor layer 44, and the interlayer connection conductor 54 provides electrical continuity between the ground conductor layer 44 and the ground conductor layer 45.

[0033] In this way, among the plurality of conductors, the conductors that are closest to the signal line laminate in the direction (X-Z plane direction) perpendicular to the longitudinal direction (Y direction) and in the layer direction (X direction) constitute ground conductor layers 42, 43, 44, and 45. These ground conductor layers 42, 43, 44, and 45 and interlayer connection conductors 51, 52, 53, 54, 55, and 56 constitute ground conductors (side ground conductors) located on the sides of the signal line laminate.

[0034] The side ground conductors and the ground conductor layers 41 and 46 act as shielding members that shield the periphery of the signal line laminate.

[0035] The first signal line 61 and the second signal line 62 have the same line width. Therefore, the signal line stack formed by the first signal line 61, the second signal line 62, and the inter-signal line insulator layer 73 has a 180-degree rotational symmetry shape with the Y direction as its axis.

[0036] In addition, in the X-Z cross section, the center of the signal line laminate coincides with the center of the hollow portion HS. Furthermore, the distance between the center of the signal line laminate and the side ground conductors is equal on the left and right sides of the figure. Therefore, although the positions of the first signal line 61 and the second signal line 62 are shifted from each other in the layer direction (X direction), the symmetry of the differential transmission line is maintained.

[0037] 1B, the interlayer connection conductors 51 to 56 are collectively referred to as the interlayer connection conductor 50. The interlayer connection conductors 50 are arranged in the longitudinal direction (Y direction) of the first signal line 61 and the second signal line 62.

[0038] Fig. 3A is a cross-sectional view of the differential transmission line 101, Fig. 3B is a plan view seen from the plane F2-F2 in Fig. 3A, and Fig. 3C is a plan view seen from the plane F1-F1 in Fig. 3A. Fig. 3A is a cross-sectional view at the X1-X1 portion in Fig. 3B and Fig. 3C.

[0039] 3A, 3B, and 3C are diagrams particularly showing the positional relationship between the first signal line 61 and the second signal line 62. When viewed in the stacking direction (Z direction), the positions of the first signal line 61 and the second signal line 62 are generally shifted in a direction (X-Z plane direction) perpendicular to the longitudinal direction (Y direction) of the first signal line 61 and the second signal line 62 and in the layer direction (X-Y plane direction), i.e., in the X direction.

[0040] It is preferable that the portion of either or both of the first signal line 61 and the second signal line 62 that comes into contact with the inter-signal line insulator layer 73 be rough and the other portion be smooth, thereby ensuring the holding force between the inter-signal line insulator layer and the first and second signal lines, while reducing the number of locations where charge concentrates due to the skin effect, thereby reducing resistance loss accordingly.

[0041] FIG. 4 is a cross-sectional view of another differential transmission line 101A according to the first embodiment. The differential transmission line 101A differs from the differential transmission line 101 shown in FIG. 1A in the configuration of the insulator layers and protective film. The differential transmission line 101A shown in FIG. 4 includes multiple insulator layers 11, 12, 13, 14, 15, and 16, an inter-signal line insulator layer 73, and multiple conductors provided along these insulator layers. A ground conductor layer 41 is located on the lower surface of the insulator layer 11. A ground conductor layer 46 is located on the lower surface of the insulator layer 16. Ground conductor layers 42, 43, 44, and 45 are located on the lower surfaces of the insulator layers 12, 13, 14, and 15, respectively.

[0042] A first signal line 61 is located on the lower surface of the inter-signal line insulator layer 73, and a second signal line 62 is located on the lower surface of the insulator layer 14 and on the upper surface of the inter-signal line insulator layer 73. In addition, a protective film 31 covers the outer surface of the ground conductor layer 41.

[0043] In this way, the ground conductor layers 41 and 46 may be located inside the laminate. The outer surface of the ground conductor layer 41 may be protected by the protective film 31.

[0044] According to the first embodiment, by shifting the positional relationship between the first signal line 61 and the second signal line 62, the electrostatic capacitance generated between the first signal line 61 and the second signal line 62 is suppressed. This allows the characteristic impedance of the differential transmission line to be set to a predetermined high value even if the distance between the first signal line 61 and the second signal line 62 is narrow. For example, LVDS (Low Voltage Differential Signaling) is used for short-distance digital wired transmission, and its characteristic impedance is generally 85 Ω to 100 Ω. Incidentally, the differential impedance is the impedance between the lines when a high-speed (high-frequency) serial signal is transmitted in odd mode on the differential transmission line. Therefore, the electrostatic capacitance generated between the first signal line 61 and the second signal line 62 affects the characteristic impedance of the differential transmission line.

[0045] Furthermore, even if the distance between the first signal line 61 and the second signal line 62 is narrow, the characteristic impedance of the differential transmission line can be set to a predetermined high value, so that an overall small-sized differential transmission line can be configured.

[0046] Furthermore, since the first signal line 61 and the second signal line 62 are fixed by an inter-signal line insulator layer, a differential transmission line with stable characteristic impedance can be obtained.

[0047] Furthermore, since the signal line stack shielded by the ground conductor has a shape of 180-degree rotational symmetry about the Y-direction, the cancellation effect is maintained not only for odd-mode differential signals but also for even-mode noise (noise generated (or applied) between the ground conductor and the first signal line 61, and between the ground conductor and the second signal line 62).

[0048] Second Embodiment In a second embodiment, a differential transmission line will be described in which the positional relationship between the first signal line 61 and the second signal line 62 and the ground conductor layer is particularly different from that in the example shown in the first embodiment.

[0049] Fig. 5(A) is a cross-sectional view of a differential transmission line 102 according to the second embodiment, Fig. 5(B) is a plan view taken along the plane F2-F2 in Fig. 5(A), and Fig. 5(C) is a plan view taken along the plane F1-F1 in Fig. 5(A). Fig. 5(A) is a cross-sectional view taken along the X1-X1 line in Fig. 5(B) and Fig. 5(C).

[0050] The differential transmission line 102 includes multiple insulator layers. A ground conductor layer is located on the lower surface of the lowest insulator layer. A ground conductor layer is located on the upper surface of the highest insulator layer. A ground conductor layer is located on the lower surface of each of the remaining insulator layers. A signal line laminate is formed by the inter-signal line insulator layer 73, the first signal line 61, and the second signal line 62. As such, the overall configuration is similar to that of the differential transmission line 101 shown in the first embodiment.

[0051] When viewed in the stacking direction (Z direction), the first signal line 61 and the second signal line 62 are generally misaligned in a direction (X-Z plane direction) perpendicular to the longitudinal direction (Y direction) of the first signal line 61 and the second signal line 62 and in the layer direction (X-Y plane direction), i.e., in the X direction. This structure is also similar to the example shown in FIG. 3A in the first embodiment.

[0052] In the second embodiment, the extension amounts of the ground conductor layers 43, 44 in the direction of the hollow portion HS differ from those in the first embodiment. That is, among the multiple ground conductor layers, the ground conductor layer 43 located on the same layer as the first signal line 61 is shifted in the same direction as the shifted direction of the first signal line 61. Similarly, the ground conductor layer 44 located on the same layer as the second signal line 62 is shifted in the same direction as the shifted direction of the second signal line 62.

[0053] 5(A), 5(B), and 5(C), the layer direction distance between the first signal line 61 and the left ground conductor layer 43 shown in Figures 5(A), 5(B), and 5(C) is P1. Similarly, the layer direction distance between the first signal line 61 and the right ground conductor layer 43 shown in Figures 5(A), 5(B), and 5(C) is also P1. Both P1s are equal.

[0054] Furthermore, the layer direction distance between the left ground conductor layer 44 shown in Figures 5(A), 5(B), and 5(C) and the second signal line 62 is P2. Similarly, the layer direction distance between the right ground conductor layer 44 shown in Figures 5(A), 5(B), and 5(C) and the second signal line 62 is also P2. Both P2s are equal. Moreover, in this example, P1 = P2.

[0055] According to the second embodiment, the electrical characteristics of the differential transmission line are stable because the distance between the first signal line 61 and the ground conductor layer 43 is the same as the distance between the second signal line 62 and the ground conductor layer 44. That is, even if there is a positional deviation in the distance between the first signal line 61 and the second signal line 62 and the ground conductor layers 43, 44, fluctuations in the capacitance between the first signal line 61 and the second signal line 62 and the ground conductor layers 43, 44 are suppressed.

[0056] Furthermore, if all of the multiple ground conductor layers are located away from the first signal line 61 and the second signal line 62, the area of ​​each ground conductor layer will become small. However, according to this embodiment, the area of ​​the entire ground conductor layer can be increased, thereby stabilizing the ground potential on the sides of the first signal line 61 and the second signal line 62 in the layer direction (the left-right direction in the figure).

[0057] Furthermore, according to this embodiment, it is possible to suppress variations in characteristics due to variations in the distances between the first signal line 61 and the second signal line 62 and the ground conductor layers 42, 43, etc.

[0058] Third Embodiment In a third embodiment, a differential transmission line having one feature in the shape of an inter-signal line insulator layer between a first signal line and a second signal line will be exemplified.

[0059] FIG. 6 is a cross-sectional view of a differential transmission line 103 according to the third embodiment.

[0060] The differential transmission line 103 includes a plurality of insulator layers 11, 12, 13, 14, 15, and 16. A ground conductor layer 41 is located on the lower surface of the insulator layer 11. A ground conductor layer 46 is located on the upper surface of the insulator layer 16. Ground conductor layers 42, 43, 44, and 45 are located on the lower surfaces of the insulator layers 12, 13, 14, and 15, respectively. A first signal line 61 is located on the lower surface of the inter-signal line insulator layer 73, and a second signal line 62 is located on the lower surface of the insulator layer 14 and on the upper surface of the inter-signal line insulator layer 73. These configurations are similar to those of the differential transmission line 101 shown in the first embodiment.

[0061] When viewed in the stacking direction (Z direction), the first signal line 61 and the second signal line 62 are generally misaligned in a direction (X-Z plane direction) orthogonal to the longitudinal direction (Y direction) of the first signal line 61 and the second signal line 62 and in the layer direction (X-Y plane direction), i.e., in the X direction. This structure is also similar to the differential transmission line 101 shown in the first embodiment.

[0062] In the third embodiment, the inter-signal line insulator layer 73 has a protruding portion that protrudes from the signal line overlapping area OR, which is the area where the first signal line 61 and the second signal line 62 overlap, when viewed in the stacking direction (Z direction). In the example shown in Fig. 6, the side surface of the inter-signal line insulator layer 73 is inclined in the layer direction (X direction).

[0063] Although Figure 6 shows an example in which the inter-signal line insulator layer 73 is provided in a range that extends beyond the signal line overlapping range OR, the inter-signal line insulator layer 73 may be provided in a range that does not extend beyond the signal line overlapping range OR while the side surfaces of the inter-signal line insulator layer 73 are inclined in the layer direction (X direction).

[0064] When manufacturing the differential transmission line 103 shown in FIG. 6 , a laminate is manufactured in a certain process, including the insulator layer 12 to which the ground conductor layer 42 is attached, the insulator layer 13 to which the ground conductor layer 43 and the first signal line 61 are attached, the inter-signal line insulator layer 73, and the insulator layer 14 to which the ground conductor layer 44 and the second signal line 62 are attached. That is, a laminate is manufactured in which the hollow portion HS is formed by overlapping openings (openings OS shown in FIG. 2 ). At this time, the opening in the insulator layer 13 is formed so that the side surface of the inter-signal line insulator layer 73 is inclined. This opening is processed by, for example, a drill, a laser, wet etching, dry etching (plasma), or the like.

[0065] According to the third embodiment, the inter-signal line insulator layer 73 extends beyond the signal line overlap range OR, and therefore the effect of suppressing the capacitance generated between the first signal line 61 and the second signal line 62 is slightly reduced. However, the increased volume of the inter-signal line insulator layer 73 sandwiched between the signal lines more firmly fixes the positional relationship between the first signal line 61 and the second signal line 62, stabilizing the characteristics of the differential transmission line.

[0066] Fourth Embodiment In a fourth embodiment, a differential transmission line having one feature in the size of an inter-signal line insulator layer between a first signal line and a second signal line will be exemplified.

[0067] FIG. 7 is a cross-sectional view of a differential transmission line 104 according to the fourth embodiment.

[0068] The differential transmission line 104 includes a plurality of insulator layers 11, 12, 13, 14, 15, and 16. A ground conductor layer 41 is located on the lower surface of the insulator layer 11. A ground conductor layer 46 is located on the upper surface of the insulator layer 16. Ground conductor layers 42, 43, 44, and 45 are located on the lower surfaces of the insulator layers 12, 13, 14, and 15, respectively. A first signal line 61 is located on the lower surface of the inter-signal line insulator layer 73, and a second signal line 62 is located on the lower surface of the insulator layer 14 and on the upper surface of the inter-signal line insulator layer 73. These configurations are similar to those of the differential transmission line 101 shown in the first embodiment.

[0069] When viewed in the stacking direction (Z direction), the first signal line 61 and the second signal line 62 are generally misaligned in a direction (X-Z plane direction) orthogonal to the longitudinal direction (Y direction) of the first signal line 61 and the second signal line 62 and in the layer direction (X-Y plane direction), i.e., in the X direction. This structure is also similar to the differential transmission line 101 shown in the first embodiment.

[0070] In the fourth embodiment, when viewed in the stacking direction (Z direction), the inter-signal line insulator layer 73 is located in a range narrower than the signal line overlapping range OR, which is the region where the first signal line 61 and the second signal line 62 overlap. In the example shown in Fig. 7, the inter-signal line insulator layer 73 is located in the center of the signal line overlapping range OR, and the first signal line 61 and the second signal line 62 have the same line width. Therefore, the signal line stack formed by the first signal line 61, the second signal line 62, and the inter-signal line insulator layer 73 has a 180-degree rotational symmetry shape with the Y direction as its axis.

[0071] According to the fourth embodiment, the volume of the inter-signal line insulator layer 73 sandwiched between the first signal line 61 and the second signal line 62 is reduced, so that the capacitance between the first signal line 61 and the second signal line 62 can be further reduced. This makes it possible to further miniaturize the differential transmission line while optimizing the characteristic impedance of the differential transmission line.

[0072] Fifth Embodiment In a fifth embodiment, a differential transmission line having one feature in the shape of an inter-signal line insulator layer between a first signal line and a second signal line will be exemplified.

[0073] FIG. 8 is a cross-sectional view of a differential transmission line 105 according to the fifth embodiment.

[0074] The differential transmission line 105 includes a plurality of insulator layers 11, 12, 13, 14, 15, and 16. A ground conductor layer 41 is located on the lower surface of the insulator layer 11. A ground conductor layer 46 is located on the upper surface of the insulator layer 16. Ground conductor layers 42, 43, 44, and 45 are located on the lower surfaces of the insulator layers 12, 13, 14, and 15, respectively. A first signal line 61 is located on the lower surface of the inter-signal line insulator layer 73, and a second signal line 62 is located on the lower surface of the insulator layer 14 and on the upper surface of the inter-signal line insulator layer 73. These configurations are similar to those of the differential transmission line 101 shown in the first embodiment.

[0075] When viewed in the stacking direction (Z direction), the first signal line 61 and the second signal line 62 are generally misaligned in a direction (X-Z plane direction) orthogonal to the longitudinal direction (Y direction) of the first signal line 61 and the second signal line 62 and in the layer direction (X-Y plane direction), i.e., in the X direction. This structure is also similar to the differential transmission line 101 shown in the first embodiment.

[0076] In the fifth embodiment, the inter-signal line insulator layer 73 has a constricted portion CP that is constricted inward in the layer direction (X direction). This constricted portion CP extends in the longitudinal direction (Y direction) of the inter-signal line insulator layer 73. The other configurations are the same as those shown in the first embodiment.

[0077] Although FIG. 8 shows an example in which the inter-signal line insulator layer 73 is provided in a range that does not extend beyond the signal line overlapping range OR, the inter-signal line insulator layer 73 may also be provided in a range that extends beyond the signal line overlapping range OR.

[0078] According to the fifth embodiment, the volume of the inter-signal line insulator layer 73 sandwiched between the first signal line 61 and the second signal line 62 is reduced, which further reduces the capacitance between the first signal line 61 and the second signal line 62. This enables the differential transmission line to be further miniaturized while optimizing the characteristic impedance of the differential transmission line. Moreover, the increased adhesive area between the first signal line 61 and the second signal line 62 and the inter-signal line insulator layer 73 enables the positional relationship between the first signal line 61 and the second signal line 62 to be firmly fixed.

[0079] Sixth Embodiment In a sixth embodiment, a differential transmission line including a plurality of differential transmission line portions will be illustrated.

[0080] FIG. 9 is a cross-sectional view of a differential transmission line 106 according to the sixth embodiment.

[0081] The differential transmission line 106 includes a plurality of insulator layers 11, 12, 13, 14, 15, and 16. A ground conductor layer 41 is located on the lower surface of the insulator layer 11. A ground conductor layer 46 is located on the upper surface of the insulator layer 16. Ground conductor layers 42, 43, 44, and 45 are located on the lower surfaces of the insulator layers 12, 13, 14, and 15, respectively. A first signal line 61a is located on the lower surface of the inter-signal line insulator layer 73a, and a second signal line 62a is located on the lower surface of the insulator layer 14 and on the upper surface of the inter-signal line insulator layer 73a. Similarly, a first signal line 61b is located on the lower surface of the inter-signal line insulator layer 73b, and a second signal line 62b is located on the lower surface of the insulator layer 14 and on the upper surface of the inter-signal line insulator layer 73b.

[0082] The first signal line 61 a, the second signal line 62 a, and the inter-signal line insulator layer 73 a form a first signal line laminate. The first signal line 61 b, the second signal line 62 b, and the inter-signal line insulator layer 73 b form a second signal line laminate. In other words, the differential transmission line 106 is a differential transmission line including two differential transmission line portions.

[0083] 9, a space due to a hollow portion HS exists between adjacent signal line laminates. The other configurations are the same as those shown in the first embodiment.

[0084] According to the sixth embodiment, the air between the two signal line laminates reduces the dielectric constant at that location. This increases the isolation between adjacent signal line laminates (differential line portions). This reduces the gap between the two signal line laminates (differential line portions), allowing the width of the two differential transmission line portions in the arrangement direction to be narrowed. This allows for the construction of a differential transmission line that is narrow in the width direction.

[0085] In the example shown in Figure 9, a differential transmission line having two signal line laminates is shown, but the same can be applied to a structure in which three or more signal line laminates are arranged in the layer direction within the hollow portion HS.

[0086] Seventh Embodiment In the seventh embodiment, a differential transmission line in which the positional relationship of a plurality of differential transmission line portions is different from that of the example shown in the sixth embodiment will be described.

[0087] The differential transmission line 107 includes a plurality of insulator layers 11, 12, 13, 14, 15, and 16. A ground conductor layer 41 is located on the lower surface of the insulator layer 11. A ground conductor layer 46 is located on the upper surface of the insulator layer 16. Ground conductor layers 42, 43, 44, and 45 are located on the lower surfaces of the insulator layers 12, 13, 14, and 15, respectively. A first signal line 61a is located on the lower surface of the inter-signal line insulator layer 73a, and a second signal line 62a is located on the lower surface of the insulator layer 14 and on the upper surface of the inter-signal line insulator layer 73a. Similarly, a first signal line 61b is located on the lower surface of the inter-signal line insulator layer 73b, and a second signal line 62b is located on the lower surface of the insulator layer 14 and on the upper surface of the inter-signal line insulator layer 73b.

[0088] The distance between the first signal line laminate including the first signal line 61 a, the second signal line 62 a, and the inter-signal line insulator layer 73 a and the second signal line laminate including the first signal line 61 b, the second signal line 62 b, and the inter-signal line insulator layer 73 b is different from that of the differential transmission line 106 shown in FIG. 9 .

[0089] In the differential transmission line 107, when viewed in the direction of stacking of the multiple insulator layers and multiple conductors, the first signal line 61a of one signal line laminate of adjacent signal line laminates overlaps with the second signal line 62b of the other signal line laminate.

[0090] In this way, even when the first signal line 61 a of one signal line laminate and the second signal line 62 b of the other signal line laminate of adjacent signal line laminates overlap when viewed in the stacking direction, the space between the first signal line 61 a and the second signal line 62 b is air, which has a low dielectric constant, and therefore high isolation between the adjacent signal line laminates (differential line portions) can be maintained.

[0091] According to the seventh embodiment, the gap between the two signal line laminates (differential line portions) can be reduced, and the width of the two differential transmission line portions in the arrangement direction can be narrowed, thereby forming a differential transmission line that is narrow in the width direction.

[0092] Eighth Embodiment In an eighth embodiment, an electronic device according to the present invention will be illustrated.

[0093] FIG. 11A is a cross-sectional view of an electronic device 508 according to the eighth embodiment. This cross-sectional position is a position in the longitudinal direction passing through and along the first signal line 61, the second signal line 62, and the inter-signal line insulator layer 73 of the differential transmission line 101A. FIG. 11B is a plan view of the electronic device 508. FIG. 11A is a cross-sectional view taken along X1-X1 in FIG. 11B.

[0094] The electronic device according to this embodiment is configured by connecting the differential transmission line 101A shown in FIG.

[0095] The electronic substrate 201 is a laminate of a plurality of insulating layers 21, 22, 23, and 24, each having a patterned conductor on one side. A protective film 32 is provided on the upper surface of the insulating layer 24.

[0096] As shown in FIG. 11A, the ends of the ground conductor layers 41 and 46, the first signal line 61, and the second signal line 62 of the differential transmission line 101A are electrically connected to the respective conductor patterns of the electronic substrate 201 via solder.

[0097] In the examples shown in Figures 11(A) and 11(B), an example is shown in which the differential transmission line 101A shown in Figure 4 is connected to the electronic board 201, but an electronic device may be configured by including any of the differential transmission lines shown in the first to fifth embodiments and another circuit board to which the differential transmission line is connected or mounted.

[0098] 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.

[0099] For example, FIG. 1A shows an example in which the inter-signal line insulator layer 73 is provided within the signal line overlapping range OR, and FIG. 7 shows an example in which the inter-signal line insulator layer 73 is provided in a range that does not extend beyond the signal line overlapping range OR, but the inter-signal line insulator layer 73 may also be provided in a range that does not fill the entire space portion SD but extends beyond the signal line overlapping range OR.

[0100] Furthermore, in each embodiment, a resin layer is exemplified as an insulator layer, but each insulator layer may be, for example, a ceramic layer (a layer formed by firing a ceramic green sheet).

[0101] In addition, in each embodiment, a differential transmission line having two signal lines (a first signal line 61 and a second signal line 62) has been shown, but multiple pairs of two signal lines that form the main part of the differential transmission line may also be provided.

[0102] Furthermore, in each embodiment, a differential transmission line having a continuous inter-signal line insulator layer sandwiched between the first signal line and the second signal line has been described. However, a differential transmission line may also be configured that includes a signal line laminate in which a space is disposed in the inter-signal line insulator layer sandwiched between the first signal line and the second signal line. With this structure, even if the line widths of the first signal line and the second signal line are increased, the capacitance between the first signal line and the second signal line can be maintained at a predetermined capacitance. This reduces the conductor loss of the differential transmission line. Furthermore, even if the distance between the first signal line and the second signal line is reduced, the capacitance generated between the first signal line and the second signal line can be suppressed. Therefore, by reducing the distance between the first signal line and the second signal line, a thin differential transmission line can be configured.

[0103] The differential transmission line and electronic device of the present invention may be provided in the following aspects.

[0104] <1> A semiconductor device comprising a plurality of insulator layers and a plurality of conductors provided along the insulator layers, wherein a laminate is formed by laminating the plurality of insulator layers and the plurality of conductors, wherein openings are formed in predetermined insulator layers among the plurality of insulator layers, thereby forming a hollow portion by overlapping of the openings in the plurality of insulator layers, wherein a first signal line and a second signal line are formed by at least two of the plurality of conductors, wherein an inter-signal line insulator layer which is at least one insulator layer among the plurality of insulator layers is present between the first signal line and the second signal line, wherein the first signal line and the second signal line are misaligned in a direction perpendicular to a longitudinal direction of the first signal line and the second signal line and in a layer direction which is a direction formed by the plurality of insulator layers and the plurality of conductor layers when viewed in the lamination direction, wherein a signal line laminate is formed by the first signal line, the second signal line, and the inter-signal line insulator layer, the inter-signal line insulator layer is arranged in a signal line overlapping range, which is a range where at least the first signal line and the second signal line overlap, when viewed in the lamination direction, and the signal line laminate is arranged in the hollow portion, thereby forming a space by the hollow portion outside the signal line overlapping range.

[0105] <2> The differential transmission line according to <1>, wherein a ground conductor layer is formed of conductors among the plurality of conductors that are located on or near the outer surface of the laminate, and wherein a ground conductor layer is formed of conductors among the plurality of conductors that are located close to the signal line laminate in the direction orthogonal to the longitudinal direction and in the layer direction.

[0106] <3> The differential transmission line according to <2>, wherein, of the ground conductor layers, a ground conductor layer located on the same layer as the first signal line is shifted in the same direction as the direction of the shift of the first signal line, and, of the ground conductor layers, a ground conductor layer located on the same layer as the second signal line is shifted in the same direction as the direction of the shift of the second signal line.

[0107] <4> The differential transmission line according to any one of <1> to <3>, wherein the inter-signal line insulator layer has a protruding portion that protrudes from the signal line overlapping area.

[0108] <5> The differential transmission line according to any one of <1> to <4>, wherein the insulator layer between the signal lines is located inside the signal line overlapping range.

[0109] <6> The differential transmission line according to any one of <1> to <5>, wherein the insulator layer of the inter-signal line insulator layer has a constricted portion that is constricted inward in the layer direction.

[0110] <7> The differential transmission line according to any one of <1> to <6>, wherein a plurality of the signal line laminates are arranged in the hollow portion in the layer direction, and a space is formed between adjacent signal line laminates among the plurality of the signal line laminates by the hollow portion.

[0111] <8> The differential transmission line according to <7>, wherein the first signal line of one of the adjacent signal line laminates overlaps with the second signal line of the other signal line laminate when viewed in the lamination direction.

[0112] <9> The differential transmission line according to any one of <1> to <8>, wherein the first signal line and the second signal line are made of any one of copper, silver, and graphite.

[0113] <10> The differential transmission line according to any one of <1> to <9>, wherein the material of the insulator layer is any one of a liquid crystal polymer resin, a polyimide resin, an epoxy resin, a fluorine resin, and a polyolefin resin.

[0114] <11> The differential transmission line according to any one of <1> to <10>, and an electronic device including the differential transmission line.

[0115] CP...constricted portion HS...hollow portion OR...signal line overlapping range OS...opening SD...space portion 11, 12, 13, 14, 15, 16...insulating layer 21, 22, 23, 24...insulating layer 31, 32...protective film 41, 46...ground conductor layer 42, 43, 44, 45, 46...ground conductor layer 51, 52, 53, 54, 55, 56...interlayer connection conductor 61, 61a, 61b...first signal line 62, 62a, 62b...second signal line 73, 73a, 73b...inter-signal line insulator layer 101, 101A, 102, 103, 104, 105...differential transmission line 201...electronic board 508...electronic device

Claims

1. A semiconductor device comprising a plurality of insulator layers and a plurality of conductors provided along the insulator layers, wherein a laminate is formed by laminating the plurality of insulator layers and the plurality of conductors, wherein openings are formed in predetermined insulator layers among the plurality of insulator layers, thereby forming a hollow portion where the openings in the plurality of insulator layers overlap, wherein a first signal line and a second signal line are formed by at least two of the plurality of conductors, wherein an inter-signal line insulator layer which is at least one insulator layer among the plurality of insulator layers is present between the first signal line and the second signal line, wherein the first signal line and the second signal line are misaligned in a direction perpendicular to the longitudinal direction of the first signal line and the second signal line and in a layer direction which is a direction formed by the plurality of insulator layers and the plurality of conductor layers when viewed in the lamination direction, wherein a signal line laminate is formed by the first signal line, the second signal line, and the inter-signal line insulator layer, wherein the first signal line and the second signal line are spaced apart via the inter-signal line insulator layer, the inter-signal line insulator layer is arranged in a signal line overlapping range, which is a range where at least the first signal line and the second signal line overlap, when viewed in the lamination direction, and the signal line laminate is arranged in the hollow portion, thereby forming a space by the hollow portion outside the signal line overlapping range.

2. The differential transmission line according to claim 1, wherein a ground conductor layer is formed of conductors among the plurality of conductors that are located on or near the outer surface of the laminate, and wherein a ground conductor layer is formed of conductors among the plurality of conductors that are located close to the signal line laminate in the direction perpendicular to the longitudinal direction and in the layer direction.

3. The differential transmission line according to claim 2, wherein, of the ground conductor layers, a ground conductor layer located on the same layer as the first signal line is shifted in the direction of the shift of the first signal line, and, of the ground conductor layers, a ground conductor layer located on the same layer as the second signal line is shifted in the direction of the shift of the second signal line.

4. The differential transmission line according to claim 1, wherein the inter-signal line insulator layer has a protruding portion that protrudes from the signal line overlapping area.

5. A differential transmission line according to any one of claims 1 to 4, wherein the insulator layer between the signal lines is located inside the signal line overlapping range.

6. The differential transmission line according to claim 1, wherein the insulator layer between the signal lines has a constricted portion that is constricted inward in the layer direction.

7. A differential transmission line according to any one of claims 1 to 6, wherein a plurality of the signal line laminates are arranged in the layer direction within the hollow portion, and a space created by the hollow portion is provided between adjacent signal line laminates among the plurality of the signal line laminates.

8. The differential transmission line according to claim 7, wherein the first signal line of one of the adjacent signal line laminates overlaps with the second signal line of the other signal line laminate when viewed in the lamination direction.

9. The differential transmission line according to any one of claims 1 to 8, wherein the material of the first signal line and the second signal line is either copper, silver, or graphite.

10. A differential transmission line according to any one of claims 1 to 9, wherein the material of the insulator layer is any one of liquid crystal polymer resin, polyimide resin, epoxy resin, fluorine resin, and polyolefin resin.

11. A differential transmission line according to any one of claims 1 to 10, and an electronic device comprising the differential transmission line.

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