Multilayer substrate

Abstract

A multilayer substrate is provided. The laminate has a structure in which a plurality of liquid crystal polymer layers including a first liquid crystal polymer layer, a second liquid crystal polymer layer, and a third liquid crystal polymer layer are laminated in the Z-axis direction. The first liquid crystal polymer layer is located at a position closest to the positive direction of the Z axis among the plurality of liquid crystal polymer layers. The third liquid crystal polymer layer is located at a position closest to the negative direction of the Z axis among the plurality of liquid crystal polymer layers. The one or more first conductor layers are located between the first liquid crystal polymer layer and the second liquid crystal polymer layer and / or between the second liquid crystal polymer layer and the third liquid crystal polymer layer. The gas transmission amount per unit volume of the first liquid crystal polymer layer and the gas transmission amount per unit volume of the third liquid crystal polymer layer are greater than the gas transmission amount per unit volume of the second liquid crystal polymer layer.

Description

Technical Field

[0001] The utility model relates to a multilayer substrate having a structure in which a plurality of liquid crystal polymer layers are stacked. Background Art

[0002] As a conventional invention related to a multilayer substrate, for example, a resin multilayer substrate described in Patent Document 1 is known. The resin multilayer substrate includes a plurality of insulating resin substrate layers and a plurality of conductor patterns. The plurality of insulating resin substrate layers are stacked in the up-down direction. The plurality of conductor patterns are provided in the resin multilayer substrate. Furthermore, holes for exhaust are provided in the plurality of conductor patterns. Thus, the gas generated inside the resin multilayer substrate during the manufacture of the resin multilayer substrate is discharged to the outside of the resin multilayer substrate through the holes.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2019 / 098012 Utility Model Content

[0006] Problems to be solved by utility models

[0007] In the field of the resin multilayer substrate described in Patent Document 1, there is a demand to release gas generated inside the resin multilayer substrate to the outside of the multilayer substrate and to suppress the intrusion of air containing moisture into the resin multilayer substrate.

[0008] Therefore, an object of the present invention is to provide a multilayer substrate capable of releasing gas generated inside the multilayer substrate to the outside of the multilayer substrate and suppressing intrusion of air containing moisture into the inside of the multilayer substrate.

[0009] Technical solutions to solve problems

[0010] A multilayer substrate according to one embodiment of the present invention comprises:

[0011] A laminate having a structure in which a plurality of liquid crystal polymer layers including a first liquid crystal polymer layer, a second liquid crystal polymer layer, and a third liquid crystal polymer layer are laminated in a Z-axis direction, wherein the first liquid crystal polymer layer is located at a position closest to the positive direction of the Z-axis among the plurality of liquid crystal polymer layers, the third liquid crystal polymer layer is located at a position closest to the negative direction of the Z-axis among the plurality of liquid crystal polymer layers, and the second liquid crystal polymer layer is located between the first liquid crystal polymer layer and the third liquid crystal polymer layer in the Z-axis direction; and

[0012] One or more conductor layers are provided in the laminate,

[0013] The one or more conductor layers include one or more first conductor layers located between the first liquid crystal polymer layer and the second liquid crystal polymer layer and / or between the second liquid crystal polymer layer and the third liquid crystal polymer layer.

[0014] The gas permeation amount per unit volume of the first liquid crystal polymer layer and the gas permeation amount per unit volume of the third liquid crystal polymer layer are greater than the gas permeation amount per unit volume of the second liquid crystal polymer layer.

[0015] Furthermore, according to the multi-layer substrate of the present invention, Young's modulus of the first liquid crystal polymer layer and Young's modulus of the third liquid crystal polymer layer may be lower than Young's modulus of the second liquid crystal polymer layer.

[0016] In addition, according to the multi-layer substrate of the present invention, the material of the first liquid crystal polymer layer and the material of the third liquid crystal polymer layer may be a wholly aromatic polyester resin containing less than 50 mol% of 2-hydroxy-6-naphthoic acid units.

[0017] The material of the second liquid crystal polymer layer is a wholly aromatic polyester resin containing 50 mol % or more of 2-hydroxy-6-naphthoic acid units.

[0018] Furthermore, according to the multi-layer substrate of the present invention, the one or more first conductor layers may include a signal conductor layer for transmitting a high-frequency signal.

[0019] The signal conductor layer is in contact with the second liquid crystal polymer layer.

[0020] The multilayer substrate further comprises a first ground conductor layer and / or a second ground conductor layer, the first ground conductor layer being located closer to the positive direction of the Z axis than the signal conductor layer and overlapping with the signal conductor layer when viewed in the Z axis direction, and the second ground conductor layer being located closer to the negative direction of the Z axis than the signal conductor layer and overlapping with the signal conductor layer when viewed in the Z axis direction,

[0021] The dielectric loss tangent of the second liquid crystal polymer layer is smaller than the dielectric loss tangent of the first liquid crystal polymer layer and the dielectric loss tangent of the third liquid crystal polymer layer.

[0022] Furthermore, according to the multi-layer substrate of the present invention, the one or more conductor layers may include a second conductor layer.

[0023] The second conductor layer is provided with a plurality of first holes penetrating the second conductor layer in the Z-axis direction.

[0024] Furthermore, according to the multi-layer substrate of the present invention, at least a portion of the plurality of first holes may have the same size as each other and may be arranged at equal intervals.

[0025] Furthermore, according to the multi-layer substrate of the present invention, the multi-layer substrate may further include an interlayer connection conductor penetrating the liquid crystal polymer layer in a vertical direction.

[0026] Furthermore, according to the multilayer substrate of the present invention, the area of ​​the first hole viewed in the Z-axis direction may be smaller than the area of ​​the interlayer connection conductor viewed in the Z-axis direction.

[0027] Furthermore, according to the multi-layer substrate of the present invention, the multi-layer substrate may further include a third conductor layer in contact with the first liquid crystal polymer layer and / or a fourth conductor layer in contact with the third liquid crystal polymer layer.

[0028] The third conductor layer is provided with a plurality of second holes penetrating the third conductor layer in the Z-axis direction, and / or the fourth conductor layer is provided with a plurality of third holes penetrating the fourth conductor layer in the Z-axis direction.

[0029] Furthermore, according to the multi-layer substrate of the present invention, the one or more first conductor layers may include an internal conductor layer in contact with the second liquid crystal polymer layer.

[0030] The multi-layer substrate further comprises a third conductor layer in contact with the first liquid crystal polymer layer and / or a fourth conductor layer in contact with the third liquid crystal polymer layer.

[0031] An area of ​​the third conductor layer and an area of ​​the fourth conductor layer are larger than an area of ​​the internal conductor layer.

[0032] In addition, according to the multilayer substrate of the present invention, the multilayer substrate may further include a first protective layer covering the main surface of the stack in the positive direction of the Z axis and / or a second protective layer covering the main surface of the stack in the negative direction of the Z axis.

[0033] The first protective layer and the second protective layer do not contain a liquid crystal polymer.

[0034] In addition, according to the multilayer substrate of the present invention, the gas permeability per unit volume of the first protective layer and the gas permeability per unit volume of the second protective layer may be greater than the gas permeability per unit volume of the first liquid crystal polymer layer and the gas permeability per unit volume of the third liquid crystal polymer layer.

[0035] Furthermore, according to the multi-layer substrate of the present invention, the multi-layer substrate may further include an interlayer connection conductor penetrating the second liquid crystal polymer layer in the Z-axis direction.

[0036] The second liquid crystal polymer layer has a positive main surface located in the positive direction of the Z axis and a negative main surface located in the negative direction of the Z axis.

[0037] The one or more first conductor layers include a fifth conductor layer located on the front main surface of the second liquid crystal polymer layer and a sixth conductor layer located on the negative main surface of the second liquid crystal polymer layer.

[0038] The interlayer connection conductor is in contact with the fifth conductor layer and the sixth conductor layer, and does not penetrate the fifth conductor layer and the sixth conductor layer in the Z-axis direction.

[0039] A multilayer substrate according to one embodiment of the present invention comprises:

[0040] A laminate having a structure in which a plurality of liquid crystal polymer layers including a first liquid crystal polymer layer, a second liquid crystal polymer layer, and a third liquid crystal polymer layer are laminated in a Z-axis direction, wherein the first liquid crystal polymer layer is located at a position closest to the positive direction of the Z-axis among the plurality of liquid crystal polymer layers, the third liquid crystal polymer layer is located at a position closest to the negative direction of the Z-axis among the plurality of liquid crystal polymer layers, and the second liquid crystal polymer layer is located between the first liquid crystal polymer layer and the third liquid crystal polymer layer in the Z-axis direction; and

[0041] One or more conductor layers are provided in the laminate,

[0042] The one or more conductor layers include one or more first conductor layers located between the first liquid crystal polymer layer and the second liquid crystal polymer layer and / or between the second liquid crystal polymer layer and the third liquid crystal polymer layer.

[0043] The second liquid crystal polymer layer has a higher crystallinity than the first liquid crystal polymer layer and the third liquid crystal polymer layer.

[0044] Utility Model Effect

[0045] According to the multi-layer substrate of the present invention, the gas generated inside the multi-layer substrate can be released to the outside of the multi-layer substrate, and the intrusion of air containing moisture into the inside of the multi-layer substrate can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is an exploded perspective view of the multi-layer substrate 10 .

[0047] Figure 2is a cross-sectional view of the multi-layer substrate 10 .

[0048] Figure 3 This is a front view of the multi-layer substrate 10 when in use.

[0049] Figure 4 It is an exploded perspective view of the multi-layer substrate 10a.

[0050] Figure 5 It is a plan view of the liquid crystal polymer layers 16a, 17, and 16c of the multi-layer substrate 10b.

[0051] Figure 6 is a cross-sectional view of the multi-layer substrate 10c.

[0052] Figure 7 This is a front view of the multi-layer substrate 10c when in use.

[0053] Figure 8 is a cross-sectional view of the multi-layer substrate 10d.

[0054] Fig. 9 is a cross-sectional view of the multi-layer substrate 10e.

[0055] Description of Reference Numerals

[0056] 10, 10a~10e: multi-layer substrate;

[0057] 12: laminate;

[0058] 16a-16c, 17, 17a, 17b: liquid crystal polymer layer;

[0059] 18a, 18b: protective layer;

[0060] 20: signal conductor layer;

[0061] 22: 1st ground conductor layer;

[0062] 24: second ground conductor layer;

[0063] 26a, 26b: signal terminals;

[0064] 28a, 28b: connecting conductor layer;

[0065] 30: the third ground conductor layer;

[0066] A1: Interval 1;

[0067] A2: Interval 2;

[0068] A3: Interval 3;

[0069] ha~hc: hole;

[0070] v1~v4, v1a~v1c: interlayer connecting conductors. DETAILED DESCRIPTION

[0071] (Implementation Method)

[0072] [Multilayer substrate structure]

[0073] Hereinafter, the structure of the multilayer substrate 10 according to the embodiment of the present invention will be described with reference to the drawings. Figure 1 It is an exploded perspective view of the multi-layer substrate 10 . Figure 2 is a cross-sectional view of the multi-layer substrate 10. Figure 2 , a cross section perpendicular to the front-rear direction is shown. Figure 3 1 is a front view of the multi-layer substrate 10 when in use. Figure 1 In FIG. 1 , only representative interlayer connection conductors v3 and v4 among the plurality of interlayer connection conductors v3 and v4 are denoted by reference numerals.

[0074] In this specification, directions are defined as follows. The stacking direction of the stacked body 12 of the multi-layer substrate 10 is defined as the up-down direction. In addition, the up-down direction is consistent with the Z-axis direction. The upper direction is the positive direction of the Z-axis. The lower direction is the negative direction of the Z-axis. In addition, the direction in which the signal conductor layer 20 of the multi-layer substrate 10 extends is defined as the left-right direction. In addition, when viewed in the up-down direction, the line width direction of the signal conductor layer 20 is defined as the front-back direction. The up-down direction, the front-back direction, and the left-right direction are orthogonal to each other. In addition, the upper direction and the lower direction of the up-down direction can also be swapped, the left direction and the right direction of the left-right direction can also be swapped, and the front direction and the rear direction of the front-back direction can also be swapped.

[0075] Hereinafter, X is a component or member of the multilayer substrate 10. In this specification, unless otherwise specified, the various parts of X are defined as follows. The front part of X refers to the front half of X. The rear part of X refers to the rear half of X. The left part of X refers to the left half of X. The right part of X refers to the right half of X. The upper part of X refers to the upper half of X. The lower part of X refers to the lower half of X. The front end of X refers to the front end of X. The rear end of X refers to the rear end of X. The left end of X refers to the left end of X. The right end of X refers to the right end of X. The upper end of X refers to the upper end of X. The lower end of X refers to the lower end of X. The front end of X refers to the front end of X and its vicinity. The rear end of X refers to the rear end of X and its vicinity. The left end of X refers to the left end of X and its vicinity. The right end of X refers to the right end of X and its vicinity. The upper end of X refers to the upper end of X and its vicinity. The lower end of X refers to the lower end of X and its vicinity.

[0076] First, refer to Figure 1 , the structure of the multilayer substrate 10 is described. The multilayer substrate 10 transmits high-frequency signals. The multilayer substrate 10 is used to electrically connect two circuits in electronic devices such as smartphones. Figure 1 As shown, the multilayer substrate 10 includes a stacked body 12, protective layers 18a, 18b, a signal conductor layer 20 (one or more conductor layers), a first grounding conductor layer 22 (one or more conductor layers), a second grounding conductor layer 24 (one or more conductor layers), signal terminals 26a, 26b (one or more conductor layers), connecting conductor layers 28a, 28b (one or more conductor layers), interlayer connecting conductors v1, v2, and a plurality of interlayer connecting conductors v3, v4.

[0077] The stack 12 has a plate shape. Therefore, the stack 12 has an upper main surface and a lower main surface. The upper main surface and the lower main surface of the stack 12 have a rectangular shape with long sides extending in the left-right direction. Therefore, the length of the stack 12 in the left-right direction is longer than the length of the stack 12 in the front-back direction. The stack 12 has flexibility.

[0078] like Figure 1 As shown, the stacked body 12 has a structure in which liquid crystal polymer layers 16a to 16c, 17 including a liquid crystal polymer layer 16a (first liquid crystal polymer layer), a liquid crystal polymer layer 17 (second liquid crystal polymer layer), and a liquid crystal polymer layer 16c (third liquid crystal polymer layer) are stacked in the Z-axis direction. The liquid crystal polymer layers 16a, 16b, 17, and 16c are arranged in order from top to bottom. Therefore, the liquid crystal polymer layer 16a (first liquid crystal polymer layer) is located at the uppermost position (positive direction of the Z-axis) among the liquid crystal polymer layers 16a to 16c, 17. The liquid crystal polymer layer 16c (third liquid crystal polymer layer) is located at the lowermost position (negative direction of the Z-axis) among the liquid crystal polymer layers 16a to 16c, 17. The liquid crystal polymer layer 17 (second liquid crystal polymer layer) is located between the liquid crystal polymer layer 16a (first liquid crystal polymer layer) and the liquid crystal polymer layer 16c (third liquid crystal polymer layer) in the up-down direction (Z-axis direction). The liquid crystal polymer layers 16 a to 16 c and the liquid crystal polymer layer 17 (second liquid crystal polymer layer) each have an upper principal surface (positive principal surface located in the positive direction of the Z axis) and a lower principal surface (negative principal surface located in the negative direction of the Z axis).

[0079] No insulating layer of a material different from the liquid crystal polymer is provided between the liquid crystal polymer layer 16a and the liquid crystal polymer layer 16b, between the liquid crystal polymer layer 16b and the liquid crystal polymer layer 17, and between the liquid crystal polymer layer 17 and the liquid crystal polymer layer 16c. Therefore, the liquid crystal polymer layer 16a and the liquid crystal polymer layer 16b are in contact with each other. Furthermore, the liquid crystal polymer layer 16a and the liquid crystal polymer layer 16b are fused together. The liquid crystal polymer layer 16b and the liquid crystal polymer layer 17 are in contact with each other. Furthermore, the liquid crystal polymer layer 16b and the liquid crystal polymer layer 17 are fused together. The liquid crystal polymer layer 17 and the liquid crystal polymer layer 16c are in contact with each other. Furthermore, the liquid crystal polymer layer 17 and the liquid crystal polymer layer 16c are fused together.

[0080] The gas permeation rate per unit volume of the liquid crystal polymer layer 16a (first liquid crystal polymer layer), the gas permeation rate per unit volume of the liquid crystal polymer layer 16b, and the gas permeation rate per unit volume of the liquid crystal polymer layer 16c (third liquid crystal polymer layer) are greater than the gas permeation rate per unit volume of the liquid crystal polymer layer 17 (second liquid crystal polymer layer). The so-called gas permeation rate refers to the oxygen permeation rate at 25°C (when in use) and the carbon dioxide permeation rate at 200°C (when the laminate is crimped). The gas permeation rate is measured, for example, by the following steps. First, a liquid crystal polymer layer having a predetermined thickness and area is prepared. A gas is sealed in the space facing the upper main surface of the liquid crystal polymer layer, and the space facing the lower main surface of the liquid crystal polymer layer is set to a vacuum state. Then, after a given time, the amount of gas present in the space facing the lower main surface of the liquid crystal polymer layer is measured. The gas is water vapor.

[0081] In order to realize the above-mentioned structure, the crystallinity of the liquid crystal polymer layer 17 (the second liquid crystal polymer layer) is higher than the crystallinity of the liquid crystal polymer layer 16a (the first liquid crystal polymer layer), the crystallinity of the liquid crystal polymer layer 16b, and the crystallinity of the liquid crystal polymer layer 16c (the third liquid crystal polymer layer). The crystallinity of the liquid crystal polymer layer is measured, for example, by X-ray diffraction, DSC (differential scanning calorimeter), FT-IR, solid NMR method, etc. DSC is, for example, DSC3 manufactured by Mettler Toledo. In the relationship between crystallinity and gas permeation, a correlation is established. Specifically, if the crystallinity becomes higher, the gas permeation decreases.

[0082] The Young's modulus of the liquid crystal polymer layer 16 a (first liquid crystal polymer layer), the Young's modulus of the liquid crystal polymer layer 16 b , and the Young's modulus of the liquid crystal polymer layer 16 c (third liquid crystal polymer layer) are lower than the Young's modulus of the liquid crystal polymer layer 17 (second liquid crystal polymer layer).

[0083] In order to realize the above-mentioned structure, the material of the liquid crystal polymer layer 16a (first liquid crystal polymer layer), the material of the liquid crystal polymer layer 16b, and the material of the liquid crystal polymer layer 16c (third liquid crystal polymer layer) are, for example, wholly aromatic polyester resins containing less than 50 mol% of 2-hydroxy-6-naphthoic acid units. The material of the liquid crystal polymer layer 17 (second liquid crystal polymer layer) is, for example, wholly aromatic polyester resins containing 50 mol% or more of 2-hydroxy-6-naphthoic acid units.

[0084] When the above-mentioned materials are used, the dielectric loss tangent of the liquid crystal polymer layer 17 (the second liquid crystal polymer layer) is smaller than the dielectric loss tangent of the liquid crystal polymer layer 16 a (the first liquid crystal polymer layer), the dielectric loss tangent of the liquid crystal polymer layer 16 b, and the dielectric loss tangent of the liquid crystal polymer layer 16 c (the third liquid crystal polymer layer).

[0085] A high-frequency signal is transmitted in the signal conductor layer 20. The signal conductor layer 20 (first conductor layer) is located between the liquid crystal polymer layer 17 (second liquid crystal polymer layer) and the liquid crystal polymer layer 16c (third liquid crystal polymer layer). In the present embodiment, the signal conductor layer 20 (first conductor layer, sixth conductor layer) is located on the lower main surface (negative main surface) of the liquid crystal polymer layer 17 (second liquid crystal polymer layer). Thus, the signal conductor layer 20 (first conductor layer, internal conductor layer) is in contact with the liquid crystal polymer layer 17 (second liquid crystal polymer layer). The signal conductor layer 20 has a linear shape extending in the left-right direction.

[0086] like Figure 1 As shown, the first ground conductor layer 22 is provided in the laminate 12. The first ground conductor layer 22 is located above the signal conductor layer 20 (in the positive direction of the Z axis), and overlaps with the signal conductor layer 20 when viewed in the up-down direction (in the Z axis direction). In the present embodiment, the first ground conductor layer 22 is located on the upper main surface of the liquid crystal polymer layer 16a. Thus, the first ground conductor layer 22 (third conductor layer) is in contact with the liquid crystal polymer layer 16a (first liquid crystal polymer layer). In addition, the first ground conductor layer 22 covers substantially the entire upper main surface of the liquid crystal polymer layer 16a. Therefore, the area of ​​the first ground conductor layer 22 (third conductor layer) is larger than the area of ​​the signal conductor layer 20 (inner conductor layer). The first ground conductor layer 22 is connected to the ground potential.

[0087] like Figure 1As shown, the second ground conductor layer 24 is provided in the laminate 12. The second ground conductor layer 24 is located below the signal conductor layer 20 (negative direction of the Z axis), and overlaps with the signal conductor layer 20 when viewed in the up-down direction (Z axis direction). In the present embodiment, the second ground conductor layer 24 is located on the lower main surface of the liquid crystal polymer layer 16c. Thus, the second ground conductor layer 24 (fourth conductor layer) is in contact with the liquid crystal polymer layer 16c (third liquid crystal polymer layer). In addition, the second ground conductor layer 24 covers substantially the entire lower main surface of the liquid crystal polymer layer 16c. Therefore, the area of ​​the second ground conductor layer 24 (fourth conductor layer) is larger than the area of ​​the signal conductor layer 20 (internal conductor layer). The second ground conductor layer 24 is connected to the ground potential. The signal conductor layer 20, the first ground conductor layer 22, and the second ground conductor layer 24 as described above have a stripline structure.

[0088] The signal terminal 26a is provided at the left end of the laminate 12. More specifically, the signal terminal 26a is located on the upper main surface of the liquid crystal polymer layer 16a. The signal terminal 26a overlaps with the left end of the signal conductor layer 20 when viewed in the vertical direction. The signal terminal 26a has a rectangular shape when viewed in the vertical direction. The signal terminal 26a is an external terminal for inputting and outputting high-frequency signals. The signal terminal 26a does not contact the first ground conductor layer 22.

[0089] The connection conductor layer 28a is provided at the left end of the stacked body 12. More specifically, the connection conductor layer 28a (first conductor layer) is located between the liquid crystal polymer layer 16a (first liquid crystal polymer layer) and the liquid crystal polymer layer 17 (second liquid crystal polymer layer). In the present embodiment, the connection conductor layer 28a is located on the lower main surface of the liquid crystal polymer layer 16b. In other words, the connection conductor layer 28a (first conductor layer, fifth conductor layer) is located on the upper main surface (front main surface) of the liquid crystal polymer layer 17 (second liquid crystal polymer layer). The connection conductor layer 28a overlaps with the left end of the signal conductor layer 20 when viewed in the vertical direction. The connection conductor layer 28a has a rectangular shape when viewed in the vertical direction.

[0090] The interlayer connection conductor v1 electrically connects the signal terminal 26a, the connection conductor layer 28a, and the left end of the signal conductor layer 20. Figure 2As shown, the interlayer connection conductor v1 includes interlayer connection conductors v1a, v1b, and v1c. The interlayer connection conductor v1a penetrates the liquid crystal polymer layer 16a in the vertical direction. The interlayer connection conductor v1a is connected to the signal terminal 26a. However, the interlayer connection conductor v1a does not penetrate the signal terminal 26a in the vertical direction. The interlayer connection conductor v1b penetrates the liquid crystal polymer layer 16b in the vertical direction. The interlayer connection conductor v1b is connected to the interlayer connection conductor v1a and the connection conductor layer 28a. However, the interlayer connection conductor v1b does not penetrate the connection conductor layer 28a in the vertical direction. The interlayer connection conductor v1c penetrates the liquid crystal polymer layer 17 (the second liquid crystal polymer layer) in the vertical direction. The interlayer connection conductor v1c is connected to the connection conductor layer 28a (the fifth conductor layer) and the signal conductor layer 20 (the sixth conductor layer). However, the interlayer connection conductor v1c does not penetrate the connection conductor layer 28a (fifth conductor layer) and the signal conductor layer 20 (sixth conductor layer) in the vertical direction (Z-axis direction). The structure of the signal terminal 26b, the connection conductor layer 28b, and the interlayer connection conductor v2 is bilaterally symmetrical with the structure of the signal terminal 26a, the connection conductor layer 28a, and the interlayer connection conductor v1, so the description is omitted.

[0091] like Figure 1 As shown, the plurality of interlayer connection conductors v3 are located in front of the signal conductor layer 20. The plurality of interlayer connection conductors v3 are arranged in a row in the left-right direction. The plurality of interlayer connection conductors v3 penetrate the liquid crystal polymer layers 16a, 16b, 17, and 16c in the up-down direction. Thus, the plurality of interlayer connection conductors v3 electrically connect the first ground conductor layer 22 and the second ground conductor layer 24.

[0092] The plurality of interlayer connection conductors v4 are located behind the signal conductor layer 20. The plurality of interlayer connection conductors v4 are arranged in a row in the left-right direction. The plurality of interlayer connection conductors v4 penetrate the liquid crystal polymer layers 16a, 16b, 17, and 16c in the up-down direction. Thus, the plurality of interlayer connection conductors v4 electrically connect the first ground conductor layer 22 and the second ground conductor layer 24.

[0093] The first ground conductor layer 22, the second ground conductor layer 24, the signal terminals 26a, 26b, and the connection conductor layers 28a, 28b are formed by, for example, etching a metal foil provided on the upper or lower main surface of the liquid crystal polymer layers 16a to 16c, 17. The metal foil is, for example, a copper foil.

[0094] In addition, the interlayer connection conductors v1 to v4 are, for example, via-hole conductors. The via-hole conductors are made by forming through holes in the liquid crystal polymer layers 16a to 16c and 17, filling the through holes with a conductive paste, and sintering the conductive paste. The material of the interlayer connection conductors v1 to v4 is a mixture of resin and metal. However, the material of the interlayer connection conductors v1 to v4 may contain metal instead of resin.

[0095] The protective layer 18a (first protective layer) covers the upper main surface (main surface in the positive direction of the Z axis) of the laminate 12. Thus, the protective layer 18a protects the first ground conductor layer 22. However, the protective layer 18a is provided with openings h1 to h6. The opening h1 overlaps with the signal terminal 26a when viewed in the vertical direction. Thus, the signal terminal 26a is exposed to the outside from the multilayer substrate 10. The opening h2 is located before the opening h1. A portion of the first ground conductor layer 22 is exposed to the outside from the multilayer substrate 10 via the opening h2. The opening h3 is located after the opening h1. A portion of the first ground conductor layer 22 is exposed to the outside from the multilayer substrate 10 via the opening h3. Thus, a portion of the first ground conductor layer 22 functions as a ground terminal. In addition, the structure of the openings h4 to h6 is bilaterally symmetrical with the structure of the openings h1 to h3, so the description is omitted.

[0096] The protective layer 18 b (second protective layer) covers the lower main surface (main surface in the negative direction of the Z axis) of the laminate 12 . Thus, the protective layer 18 b protects the second ground conductor layer 24 .

[0097] The protective layers 18a and 18b described above do not contain a liquid crystal polymer. Therefore, the protective layers 18a and 18b are not part of the laminate 12. The protective layers 18a and 18b are, for example, barrier layers. In addition, the gas permeation rate per unit volume of the protective layer 18a (first protective layer) and the gas permeation rate per unit volume of the protective layer 18b (second protective layer) are greater than the gas permeation rate per unit volume of the liquid crystal polymer layer 16a (first liquid crystal polymer layer) and the gas permeation rate per unit volume of the liquid crystal polymer layer 16c (third liquid crystal polymer layer). Such protective layers 18a and 18b are formed after the thermal compression bonding process of the laminate 12.

[0098] The multilayer substrate 10 as described above has flexibility. Figure 3As shown, the multilayer substrate 10 is capable of bending. Specifically, the multilayer substrate 10 has a first section A1, a second section A2, and a third section A3. The first section A1, the second section A2, and the third section A3 are arranged in sequence from left to right when the multilayer substrate 10 is not bent. Moreover, the second section A2 is bent in a downward direction relative to the first section A1. On the other hand, the first section A1 and the third section A3 are not bent. However, the first section A1 and the third section A3 may also be slightly bent. In this case, the radius of curvature of the first section A1 and the radius of curvature of the third section A3 are larger than the radius of curvature of the second section A2.

[0099] [Effect]

[0100] According to the multi-layer substrate 10, the gas generated inside the multi-layer substrate 10 can be released to the outside of the multi-layer substrate 10, and the air containing moisture can be suppressed from entering the inside of the multi-layer substrate 10. More specifically, in the multi-layer substrate 10, the gas permeation rate per unit volume of the liquid crystal polymer layer 16a (first liquid crystal polymer layer) and the gas permeation rate per unit volume of the liquid crystal polymer layer 16c (third liquid crystal polymer layer) are greater than the gas permeation rate per unit volume of the liquid crystal polymer layer 17 (second liquid crystal polymer layer). As a result, the gas generated inside the multi-layer substrate 10 during manufacturing is released to the outside of the multi-layer substrate 10 through the liquid crystal polymer layers 16a and 16c. On the other hand, when the multi-layer substrate 10 is used, the air containing moisture is not easy to enter the inside of the multi-layer substrate 10 because of the presence of the liquid crystal polymer layer 17. As a result, the moisture present in the liquid crystal polymer layer 17 is reduced.

[0101] Here, the lower main surface of the connection conductor layer 28a, 28b (first conductor layer) located between the liquid crystal polymer layer 16a (first liquid crystal polymer layer) and the liquid crystal polymer layer 17 (second liquid crystal polymer layer) is located near the liquid crystal polymer layer 17. In the present embodiment, the lower main surface of the connection conductor layer 28a, 28b (first conductor layer) is in contact with the liquid crystal polymer layer 17. Therefore, if the moisture present in the liquid crystal polymer layer 17 is reduced, it is possible to suppress the corrosion of the lower main surface of the connection conductor layer 28a, 28b (first conductor layer) by moisture. Similarly, the upper main surface of the signal conductor layer 20 (first conductor layer) located between the liquid crystal polymer layer 17 (second liquid crystal polymer layer) and the liquid crystal polymer layer 16c (third liquid crystal polymer layer) is located near the liquid crystal polymer layer 17. In the present embodiment, the upper main surface of the signal conductor layer 20 (first conductor layer) is in contact with the liquid crystal polymer layer 17. Therefore, if the moisture content in the liquid crystal polymer layer 17 is reduced, it is possible to suppress the vicinity of the upper main surface of the signal conductor layer 20 from being corroded by moisture.

[0102] In addition, if Figure 3When the multilayer substrate 10 is bent, a large tensile stress is applied to the liquid crystal polymer layer 16a, a large compressive stress is applied to the liquid crystal polymer layer 16c, and the compressive stress and the tensile stress are not easily applied to the liquid crystal polymer layer 17. Therefore, the crystallinity of the liquid crystal polymer layer 16a (first liquid crystal polymer layer) and the crystallinity of the liquid crystal polymer layer 16c (third liquid crystal polymer layer) are lower than the crystallinity of the liquid crystal polymer layer 17 (second liquid crystal polymer layer). As a result, the Young's modulus of the liquid crystal polymer layer 16a and the Young's modulus of the liquid crystal polymer layer 16c become lower than the Young's modulus of the liquid crystal polymer layer 17. Therefore, the liquid crystal polymer layers 16a and 16c become easily deformed, and the damage of the liquid crystal polymer layers 16a and 16c can be suppressed.

[0103] In addition, the liquid crystal polymer layers 16a to 16c, 17 have a characteristic of being easily plastically deformed by heating. However, the liquid crystal polymer layers 16a to 16c, 17 are easy to generate gas when heated. Furthermore, when the multi-layer substrate 10 is bent, it is preferable that the Young's modulus of the liquid crystal polymer layers 16a and 16c near the surface of the laminate 12 is low. Therefore, in the multi-layer substrate 10, the crystallinity of the liquid crystal polymer layers 16a and 16c is low. As a result, the gas generated in the laminate 12 is released to the outside of the laminate, and the laminate 12 becomes easy to bend.

[0104] In addition, the material of the liquid crystal polymer layer 16a (first liquid crystal polymer layer), the material of the liquid crystal polymer layer 16b, and the material of the liquid crystal polymer layer 16c (third liquid crystal polymer layer) are, for example, wholly aromatic polyester resins containing less than 50 mol% of 2-hydroxy-6-naphthoic acid units. The material of the liquid crystal polymer layer 17 (second liquid crystal polymer layer) is, for example, wholly aromatic polyester resins containing 50 mol% or more of 2-hydroxy-6-naphthoic acid units. As a result, the gas permeation rate per unit volume of the liquid crystal polymer layer 16a (first liquid crystal polymer layer) and the gas permeation rate per unit volume of the liquid crystal polymer layer 16c (third liquid crystal polymer layer) are greater than the gas permeation rate per unit volume of the liquid crystal polymer layer 17 (second liquid crystal polymer layer). As a result, according to the multilayer substrate 10, the gas generated inside the multilayer substrate 10 can be released to the outside of the multilayer substrate 10, and the air containing moisture can be suppressed from entering the inside of the multilayer substrate 10.

[0105] The signal conductor layer 20 is in contact with the liquid crystal polymer layer 17 (second liquid crystal polymer layer). Among the above-mentioned materials, the dielectric loss tangent of the liquid crystal polymer layer 17 (second liquid crystal polymer layer) is smaller than the dielectric loss tangent of the liquid crystal polymer layer 16a (first liquid crystal polymer layer) and the dielectric loss tangent of the liquid crystal polymer layer 16c (third liquid crystal polymer layer). As a result, the dielectric loss generated in the high-frequency signal transmitted by the signal conductor layer 20 is reduced.

[0106] Furthermore, according to the multilayer substrate 10, the gas generated inside the multilayer substrate 10 can be released to the outside of the multilayer substrate 10, and the intrusion of air containing moisture into the multilayer substrate 10 can be suppressed. More specifically, the laminate 12 is manufactured by laminating the liquid crystal polymer layers 16a to 16c and 17 and then heating and pressing the liquid crystal polymer layers 16a to 16c and 17. During the heating and pressing, gas is generated inside the laminate 12. Therefore, the signal conductor layer 20 (internal conductor layer) having a small area is in contact with the liquid crystal polymer layer 17 (second liquid crystal polymer layer) having a small gas permeation amount. The first ground conductor layer 22 (third conductor layer) having a large area is in contact with the liquid crystal polymer layer 16a (first liquid crystal polymer layer) having a large gas permeation amount. The second ground conductor layer 24 (fourth conductor layer) having a large area is in contact with the liquid crystal polymer layer 16c (third liquid crystal polymer layer) having a large gas permeation amount. Thus, since the liquid crystal polymer layer 17 is not largely covered by the signal conductor layer 20, the gas in the liquid crystal polymer layer 17 is easily released to the outside of the multi-layer substrate 10. As a result, the signal conductor layer 20 and the connection conductor layers 28a and 28b can be suppressed from peeling off in the multi-layer substrate 10. In addition, since the liquid crystal polymer layers 16a and 16c are largely covered by the first ground conductor layer 22 and the second ground conductor layer 24, the intrusion of air containing moisture into the interior of the multi-layer substrate 10 can be suppressed.

[0107] Furthermore, the gas permeation rate per unit volume of the protective layer 18a (first protective layer) and the gas permeation rate per unit volume of the protective layer 18b (second protective layer) are greater than the gas permeation rate per unit volume of the liquid crystal polymer layer 16a (first liquid crystal polymer layer) and the gas permeation rate per unit volume of the liquid crystal polymer layer 16c (third liquid crystal polymer layer). Thus, the gas generated inside the multi-layer substrate 10 can be further released to the outside of the multi-layer substrate 10, and the intrusion of air containing moisture into the inside of the multi-layer substrate 10 can be further suppressed.

[0108] In the multilayer substrate 10, the material of the interlayer connection conductor v1c is a mixture of resin and metal. Such an interlayer connection conductor v1c is cured by heating during manufacturing. At this time, the interlayer connection conductor v1c generates gas. Moreover, the interlayer connection conductor v1c does not penetrate the connection conductor layer 28a (5th conductor layer) and the signal conductor layer 20 (6th conductor layer) in the up and down direction (Z-axis direction). Therefore, the gas is easily trapped between the connection conductor layer 28a (5th conductor layer) and the signal conductor layer 20 (6th conductor layer).

[0109] Therefore, in the multi-layer substrate 10, the gas permeation rate per unit volume of the liquid crystal polymer layer 16a (first liquid crystal polymer layer) and the gas permeation rate per unit volume of the liquid crystal polymer layer 16c (third liquid crystal polymer layer) are greater than the gas permeation rate per unit volume of the liquid crystal polymer layer 17 (second liquid crystal polymer layer). As a result, the gas generated inside the multi-layer substrate 10 during manufacturing is released to the outside of the multi-layer substrate 10 through the liquid crystal polymer layers 16a and 16c. On the other hand, when the multi-layer substrate 10 is used, the air containing moisture passes through the liquid crystal polymer layer 17 and is less likely to enter the inside of the multi-layer substrate 10. As a result, the moisture present in the liquid crystal polymer layer 17 is reduced.

[0110] (First Modification)

[0111] Hereinafter, a multilayer substrate 10a according to a first modification will be described with reference to the drawings. Figure 4 It is an exploded perspective view of the multi-layer substrate 10a.

[0112] The multilayer substrate 10a is different from the multilayer substrate 10 in that it further includes a third ground conductor layer 30. The third ground conductor layer 30 is located on the lower main surface of the liquid crystal polymer layer 17. The third ground conductor layer 30 covers most of the liquid crystal polymer layer 17. However, the third ground conductor layer 30 is insulated from the signal conductor layer 20. The third ground conductor layer 30 surrounds the signal conductor layer 20 as viewed in the vertical direction. The third ground conductor layer 30 is electrically connected to the first ground conductor layer 22 and the second ground conductor layer 24 via interlayer connection conductors v3 and v4. Therefore, the third ground conductor layer 30 is connected to the ground potential. The other structures of the multilayer substrate 10a are the same as those of the multilayer substrate 10, so the description is omitted. The multilayer substrate 10a can exert the same effects as the multilayer substrate 10.

[0113] (Second modification)

[0114] Hereinafter, a multilayer substrate 10b according to a second modification will be described with reference to the drawings. Figure 5 It is a plan view of the liquid crystal polymer layers 16a, 17, and 16c of the multi-layer substrate 10b.

[0115] The multilayer substrate 10b is different from the multilayer substrate 10a in that a plurality of holes ha to hc are provided. More specifically, the third ground conductor layer 30 (second conductor layer) is in contact with the liquid crystal polymer layer 17 (second liquid crystal polymer layer). The third ground conductor layer 30 (second conductor layer) is provided with a plurality of holes ha (first holes) that penetrate the third ground conductor layer 30 (second conductor layer) in the up-down direction (Z-axis direction). At least a portion of the plurality of holes ha (first holes) have the same size as each other and are arranged at equal intervals. In this embodiment, the plurality of holes ha are arranged in two rows. The plurality of holes ha are arranged in the left-right direction. The area of ​​the hole ha (first hole) observed in the up-down direction (Z-axis direction) is smaller than the area of ​​the interlayer connection conductors v1 to v4 observed in the up-down direction (Z-axis direction). The area of ​​the interlayer connection conductors v1 to v4 observed in the up-down direction is the area of ​​the region surrounded by the outer edges of the interlayer connection conductors v1 to v4 that are viewed in the up-down direction. The hole ha is provided only in the third ground conductor layer 30, and is not provided in the liquid crystal polymer layer 17. For example, the hole ha is not a through hole in which a metal is provided on the inner peripheral surface of a through hole penetrating the liquid crystal polymer layer 17 in the vertical direction.

[0116] The first ground conductor layer 22 (third conductor layer) is in contact with the liquid crystal polymer layer 16a (first liquid crystal polymer layer). The first ground conductor layer 22 (third conductor layer) is provided with a plurality of holes hb (second holes) penetrating the first ground conductor layer 22 (third conductor layer) in the up-down direction (Z-axis direction). At least a portion of the plurality of holes hb (second holes) have the same size as each other and are arranged at equal intervals. In the present embodiment, the plurality of holes hb are arranged in two rows. The plurality of holes hb are arranged in the left-right direction. The area of ​​the hole hb (second hole) observed in the up-down direction (Z-axis direction) is smaller than the area of ​​the hole ha (first hole) observed in the up-down direction (Z-axis direction).

[0117] The second ground conductor layer 24 (the fourth conductor layer) is in contact with the liquid crystal polymer layer 16c (the third liquid crystal polymer layer). The second ground conductor layer 24 (the fourth conductor layer) is provided with a plurality of holes hc (the third holes) penetrating the second ground conductor layer 24 (the fourth conductor layer) in the vertical direction (the Z-axis direction). At least a portion of the plurality of holes hc (the third holes) have the same size as each other and are arranged at equal intervals. In the present embodiment, the plurality of holes hc are arranged in two rows. The plurality of holes hc are arranged in the left-right direction. The area of ​​the hole hc (the third hole) observed in the vertical direction (the Z-axis direction) is smaller than the area of ​​the hole ha (the first hole) observed in the vertical direction (the Z-axis direction). The other structures of the multilayer substrate 10b are the same as those of the multilayer substrate 10a, so the description is omitted. The multilayer substrate 10b can exert the same effects as the multilayer substrate 10a.

[0118] As described above, the area of ​​the hole hb (second hole) observed in the vertical direction (Z-axis direction) or the area of ​​the hole hc (third hole) observed in the vertical direction (Z-axis direction) is smaller than the area of ​​the hole ha (first hole) observed in the vertical direction (Z-axis direction). Thus, it is possible to suppress the leakage of noise through the liquid crystal polymer layer 16a.

[0119] In addition, the hole hb provided in the first ground conductor layer 22 and the hole hc provided in the second ground conductor layer 24 have small areas, so that the radiation of noise from the multilayer substrate 10b can be suppressed, and the intrusion of noise into the multilayer substrate 10b can be suppressed. In addition, the potential of the first ground conductor layer 22 and the second ground conductor layer 24 becomes stable at the ground potential.

[0120] (Third Modification)

[0121] Hereinafter, a multilayer substrate 10c according to a third modification will be described with reference to the drawings. Figure 6 is a cross-sectional view of the multi-layer substrate 10c. Figure 7 This is a front view of the multi-layer substrate 10c when in use.

[0122] The multilayer substrate 10c is different from the multilayer substrate 10 in that the thickness of the second section A2 in the vertical direction is smaller than the thickness of the first section A1 in the vertical direction and the thickness of the third section A3 in the vertical direction. In the second section A2, there are no liquid crystal polymer layers 16a, 16b, and 17. Therefore, the second section A2 is more easily deformed than the first section A1 and the third section A3. That is, the second section A2 functions as a flexible area. The first section A1 and the third section A3 function as rigid areas. Moreover, as Figure 7 As shown, the second section A2 is bent downward relative to the first section A1. The other structures of the multilayer substrate 10c are the same as those of the multilayer substrate 10, and thus the description thereof is omitted. The multilayer substrate 10c can achieve the same effects as those of the multilayer substrate 10.

[0123] In the multilayer substrate 10c, the liquid crystal polymer layer 17 having a high Young's modulus does not exist in the second section A2. As a result, the second section A2 becomes more easily bendable. The Young's modulus is the Young's modulus at room temperature. The room temperature is, for example, 5°C or higher and 35°C or lower.

[0124] (Fourth Modification)

[0125] Hereinafter, a multilayer substrate 10d according to a fourth modification will be described with reference to the drawings. Figure 8 is a cross-sectional view of the multi-layer substrate 10d.

[0126] The multilayer substrate 10d is different from the multilayer substrate 10 in that the liquid crystal polymer layer 17 is not provided in the second section A2. As such, the liquid crystal polymer layer 17 having a high Young's modulus does not exist in the second section A2. As a result, the second section A2 becomes easier to bend. The other structures of the multilayer substrate 10d are the same as those of the multilayer substrate 10, and thus the description thereof is omitted. The multilayer substrate 10d can exert the same effects as those of the multilayer substrate 10.

[0127] (Fifth Modification)

[0128] Hereinafter, a multilayer substrate 10e according to a fifth modification will be described with reference to the drawings. Fig. 9 is a cross-sectional view of the multi-layer substrate 10e.

[0129] The multilayer substrate 10e is different from the multilayer substrate 10c in that the laminate 12 further includes liquid crystal polymer layers 17a and 17b. More specifically, the liquid crystal polymer layer 17a is laminated on the top of the liquid crystal polymer layer 17. The liquid crystal polymer layer 17b is laminated on the bottom of the liquid crystal polymer layer 17. In this way, a plurality of liquid crystal polymer layers with a small gas permeability may be provided. Thus, the signal conductor layer 20 sandwiches the liquid crystal polymer layers 17 and 17b with a small gas permeability from the top and bottom. As a result, corrosion of the signal conductor layer 20 can be suppressed. The other structures of the multilayer substrate 10e are the same as those of the multilayer substrate 10, and therefore the description thereof is omitted. The multilayer substrate 10e can exert the same effects as the multilayer substrate 10c.

[0130] (Other Implementation Methods)

[0131] The multilayer substrate of the present invention is not limited to the multilayer substrates 10 and 10a to 10e, and can be modified within the scope of the gist thereof. In addition, the structures of the multilayer substrates 10 and 10a to 10e can be arbitrarily combined.

[0132] In addition, the protective layers 18a and 18b are not essential components. In addition, either the protective layer 18a or the protective layer 18b may be provided.

[0133] The first ground conductor layer 22 and the second ground conductor layer 24 are not essential components. Alternatively, either the first ground conductor layer 22 or the second ground conductor layer 24 may be provided.

[0134] In addition, the liquid crystal polymer layers 16a to 16c and 17 may be made of the same material. In this case, the liquid crystal polymer layers 16a to 16c and 17 are made of, for example, porous materials. Moreover, the porosity of the liquid crystal polymer layer 17 is lower than that of the liquid crystal polymer layers 16a to 16c. As a result, the gas permeation amount per unit volume of the liquid crystal polymer layers 16a to 16c becomes greater than the gas permeation amount per unit volume of the liquid crystal polymer layer 17. As a result, the gas in the stack 12 is released to the outside of the stack 12.

[0135] Alternatively, the first conductor layer may be located only between the liquid crystal polymer layer 16 a (first liquid crystal polymer layer) and the liquid crystal polymer layer 17 (second liquid crystal polymer layer) or between the liquid crystal polymer layer 17 (second liquid crystal polymer layer) and the liquid crystal polymer layer 16 c (third liquid crystal polymer layer).

[0136] In addition, the interlayer connection conductors v1 to v4 may not be via-hole conductors. The interlayer connection conductors v1 to v4 may be through-hole conductors. The through-hole conductors are formed by plating the inner peripheral surface of a through hole that penetrates the liquid crystal polymer layer in the vertical direction.

[0137] In addition, the protective layers 18a and 18b are provided for the purpose of preventing the conductor layer from being exposed and thus corroding the conductor layer. Therefore, the gas permeation rate per unit volume of the protective layers 18a and 18b may be greater than the gas permeation rate per unit volume of the liquid crystal polymer layers 16a and 16c. Therefore, the gas permeation rate per unit volume of the protective layers 18a and 18b may be less than the gas permeation rate per unit volume of the liquid crystal polymer layers 16a and 16c.

[0138] Furthermore, the interlayer connection conductor v1 c may penetrate the connection conductor layer 28 a (fifth conductor layer) and the signal conductor layer 20 (sixth conductor layer) in the up-down direction (Z-axis direction).

[0139] In the multilayer substrate 10e, a liquid crystal polymer layer may be provided between the liquid crystal polymer layer 17a and the liquid crystal polymer layer 17. In addition, a liquid crystal polymer layer may be provided between the liquid crystal polymer layer 17 and the liquid crystal polymer layer 17b. The liquid crystal polymer has a gas permeability greater than the gas permeability per unit volume of the liquid crystal polymer layers 17, 17a, and 17b.

[0140] The plurality of holes Ha may be provided in a conductor layer other than the third ground conductor layer 30 , as long as they are provided in a conductor layer provided in the laminated body 12 .

Claims

1. A multi-layer substrate, characterized in that: have: A laminate having a structure in which a plurality of liquid crystal polymer layers including a first liquid crystal polymer layer, a second liquid crystal polymer layer, and a third liquid crystal polymer layer are laminated in a Z-axis direction, wherein the first liquid crystal polymer layer is located at a position closest to the positive direction of the Z-axis among the plurality of liquid crystal polymer layers, the third liquid crystal polymer layer is located at a position closest to the negative direction of the Z-axis among the plurality of liquid crystal polymer layers, and the second liquid crystal polymer layer is located between the first liquid crystal polymer layer and the third liquid crystal polymer layer in the Z-axis direction; and One or more conductor layers are provided in the laminate, The one or more conductor layers include one or more first conductor layers located between the first liquid crystal polymer layer and the second liquid crystal polymer layer and / or between the second liquid crystal polymer layer and the third liquid crystal polymer layer. The gas permeation amount per unit volume of the first liquid crystal polymer layer and the gas permeation amount per unit volume of the third liquid crystal polymer layer are greater than the gas permeation amount per unit volume of the second liquid crystal polymer layer.

2. The multi-layer substrate according to claim 1, characterized in that The Young's modulus of the first liquid crystal polymer layer and the Young's modulus of the third liquid crystal polymer layer are lower than the Young's modulus of the second liquid crystal polymer layer.

3. The multi-layer substrate according to claim 1, characterized in that The material of the first liquid crystal polymer layer and the material of the third liquid crystal polymer layer are wholly aromatic polyester resins containing less than 50 mol% of 2-hydroxy-6-naphthoic acid units. The material of the second liquid crystal polymer layer is a wholly aromatic polyester resin containing 50 mol % or more of 2-hydroxy-6-naphthoic acid units.

4. The multilayer substrate according to any one of claims 1 to 3, characterized in that: The one or more first conductor layers include a signal conductor layer for transmitting a high-frequency signal. The signal conductor layer is in contact with the second liquid crystal polymer layer. The multilayer substrate further comprises a first ground conductor layer and / or a second ground conductor layer, the first ground conductor layer being located closer to the positive direction of the Z axis than the signal conductor layer and overlapping with the signal conductor layer when viewed in the Z axis direction, and the second ground conductor layer being located closer to the negative direction of the Z axis than the signal conductor layer and overlapping with the signal conductor layer when viewed in the Z axis direction, The dielectric loss tangent of the second liquid crystal polymer layer is smaller than the dielectric loss tangent of the first liquid crystal polymer layer and the dielectric loss tangent of the third liquid crystal polymer layer.

5. The multi-layer substrate according to any one of claims 1 to 3, characterized in that The one or more conductor layers include a second conductor layer, The second conductor layer is provided with a plurality of first holes penetrating the second conductor layer in the Z-axis direction.

6. The multi-layer substrate according to claim 5, characterized in that At least a portion of the plurality of first holes have the same size as one another and are arranged at equal intervals.

7. The multi-layer substrate according to claim 5, characterized in that The multi-layer substrate further includes an interlayer connection conductor penetrating the liquid crystal polymer layer in a vertical direction.

8. The multi-layer substrate according to claim 7, characterized in that: An area of ​​the first hole viewed in the Z-axis direction is smaller than an area of ​​the interlayer connection conductor viewed in the Z-axis direction.

9. The multi-layer substrate according to claim 5, characterized in that: The multi-layer substrate further comprises a third conductor layer in contact with the first liquid crystal polymer layer and / or a fourth conductor layer in contact with the third liquid crystal polymer layer. The third conductor layer is provided with a plurality of second holes penetrating the third conductor layer in the Z-axis direction, and / or the fourth conductor layer is provided with a plurality of third holes penetrating the fourth conductor layer in the Z-axis direction.

10. The multi-layer substrate according to any one of claims 1 to 3, characterized in that: The one or more first conductor layers include an internal conductor layer in contact with the second liquid crystal polymer layer. The multi-layer substrate further comprises a third conductor layer in contact with the first liquid crystal polymer layer and / or a fourth conductor layer in contact with the third liquid crystal polymer layer. An area of ​​the third conductor layer and an area of ​​the fourth conductor layer are larger than an area of ​​the internal conductor layer.

11. The multi-layer substrate according to any one of claims 1 to 3, characterized in that: The multilayer substrate further comprises a first protective layer covering a main surface of the stack in the positive direction of the Z axis and / or a second protective layer covering a main surface of the stack in the negative direction of the Z axis. The first protective layer and the second protective layer do not contain a liquid crystal polymer.

12. The multi-layer substrate according to claim 11, characterized in that: The gas permeation rate per unit volume of the first protective layer and the gas permeation rate per unit volume of the second protective layer are greater than the gas permeation rate per unit volume of the first liquid crystal polymer layer and the gas permeation rate per unit volume of the third liquid crystal polymer layer.

13. The multi-layer substrate according to claim 12, characterized in that: The multi-layer substrate further includes an interlayer connection conductor penetrating the second liquid crystal polymer layer in the Z-axis direction. The second liquid crystal polymer layer has a positive main surface located in the positive direction of the Z axis and a negative main surface located in the negative direction of the Z axis. The one or more first conductor layers include a fifth conductor layer located on the front main surface of the second liquid crystal polymer layer and a sixth conductor layer located on the negative main surface of the second liquid crystal polymer layer. The interlayer connection conductor is in contact with the fifth conductor layer and the sixth conductor layer, and does not penetrate the fifth conductor layer and the sixth conductor layer in the Z-axis direction.

14. A multi-layer substrate, characterized in that: have: A laminate having a structure in which a plurality of liquid crystal polymer layers including a first liquid crystal polymer layer, a second liquid crystal polymer layer, and a third liquid crystal polymer layer are laminated in a Z-axis direction, wherein the first liquid crystal polymer layer is located at a position closest to the positive direction of the Z-axis among the plurality of liquid crystal polymer layers, the third liquid crystal polymer layer is located at a position closest to the negative direction of the Z-axis among the plurality of liquid crystal polymer layers, and the second liquid crystal polymer layer is located between the first liquid crystal polymer layer and the third liquid crystal polymer layer in the Z-axis direction; and One or more conductor layers are provided in the laminate, The one or more conductor layers include one or more first conductor layers located between the first liquid crystal polymer layer and the second liquid crystal polymer layer and / or between the second liquid crystal polymer layer and the third liquid crystal polymer layer. The second liquid crystal polymer layer has a higher crystallinity than the first liquid crystal polymer layer and the third liquid crystal polymer layer.

15. The multi-layer substrate according to claim 14, characterized in that The Young's modulus of the first liquid crystal polymer layer and the Young's modulus of the third liquid crystal polymer layer are lower than the Young's modulus of the second liquid crystal polymer layer.

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