Laminated substrate

Abstract

A laminated substrate 1 comprises: a first resin layer 10a having a first main surface 10 aa and a second main surface 10 ab which are mutually opposing in the thickness direction; a second resin layer 10b that has a third main surface 10ba and a fourth main surface 10bb which are mutually opposing in the thickness direction and that is provided so that the fourth main surface 10bb faces the first main surface 10aa; and a first conductor layer 20a that is located between the first resin layer 10a and the second resin layer 10b and that is provided so as to be in contact with the first main surface 10aa and the fourth main surface 10bb. The first resin layer 10a and the second resin layer 10b each include: a first resin material 11a comprising a thermoplastic resin; and a second resin material 11b comprising a thermoplastic resin and dispersed in the first resin material 11a. When the melting point of the first resin material 11a is Tm1 and the melting point of the second resin material 11b is Tm2, Tm1 > Tm2. In a plane direction perpendicular to the thickness direction, when the coefficient of thermal expansion of the first resin material 11a is CTE 1, the coefficient of thermal expansion of the second resin material 11b is CTE 2, and the coefficient of thermal expansion of the first conductor layer 20a is CTE 3, ｜ＣＴＥ３－ＣＴＥ２｜＞｜ＣＴＥ３－ＣＴＥ１｜. When a first cross-section along the thickness direction is viewed, the abundance proportion of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is 40-70%.

Description

Multilayer substrate

[0001] The present invention relates to a laminated substrate.

[0002] Patent Document 1 discloses a laminate including a thermoplastic first resin layer, a conductor pattern formed on one main surface of the first resin layer, and a thermoplastic second resin layer, wherein the first resin layer is softer than the second resin layer and has a lower dielectric constant than the second resin layer, and the conductor pattern has a portion that contacts the first resin layer along the layer direction of the first resin layer and a portion that contacts the first resin layer along the stacking direction of the first resin layer, the second resin layer, and the conductor pattern.

[0003] International Publication No. 2020 / 071473

[0004] In the laminate described in Patent Document 1, as shown in FIG. 1 and the like of Patent Document 1, a first resin layer made primarily of a fluororesin that is prone to dimensional change (e.g., has a large thermal expansion coefficient) when heated is provided in a layered form. Therefore, the laminate described in Patent Document 1 is configured such that the first resin layer is prone to dimensional change. Furthermore, in the laminate described in Patent Document 1, it is considered that the conductor pattern is less prone to dimensional change than the first resin layer (e.g., has a small thermal expansion coefficient). For these reasons, in the laminate described in Patent Document 1, the dimensional change of the first resin layer is prone to change, and further, the dimensional change of the first resin layer and the conductor pattern is different, which may result in a decrease in adhesion between the first resin layer and the conductor pattern or warping of the laminate.

[0005] The present invention has been made to solve the above problems, and has an object to provide a laminated substrate that has excellent adhesion between a resin layer and a conductor layer and is suppressed from warping.

[0006] The laminated substrate of the present invention comprises: a first resin layer having a first main surface and a second main surface opposed to each other in a thickness direction; a second resin layer having a third main surface and a fourth main surface opposed to each other in the thickness direction, the fourth main surface being opposed to the first main surface; and a first conductor layer located between the first resin layer and the second resin layer and being in contact with the first main surface and the fourth main surface, wherein the first resin layer and the second resin layer each contain a first resin material made of a thermoplastic resin and a second resin material made of a thermoplastic resin and dispersed in the first resin material; If the melting point of the first resin material is Tm1 and the melting point of the second resin material is Tm2, ​​then Tm1 > Tm2; if, in a plane direction perpendicular to the thickness direction, the thermal expansion coefficient of the first resin material is CTE1, the thermal expansion coefficient of the second resin material is CTE2, and the thermal expansion coefficient of the first conductor layer is CTE3, then |CTE3-CTE2| > |CTE3-CTE1|; and when viewing a first cross section along the thickness direction, the abundance ratio of the second resin material at the interface between the first resin layer and the first conductor layer is 40% or more and 70% or less.

[0007] According to the present invention, it is possible to provide a laminated substrate in which the adhesion between the resin layer and the conductor layer is excellent and warping is suppressed.

[0008] FIG. 1 is a cross-sectional view schematically showing an example of a laminated substrate according to Embodiment 1 of the present invention, as viewed at a first cross section along the thickness direction. FIG. 2 is a cross-sectional view schematically showing an example of a laminated substrate according to Embodiment 1 of the present invention, as viewed at a second cross section perpendicular to the first cross section along the thickness direction. FIG. 3 is a cross-sectional view schematically showing an enlarged portion of the laminated substrate shown in FIG. 1 , and is a cross-sectional view for explaining a method for determining the abundance ratio of the second resin material at the interface between the first resin layer and the first conductor layer. FIG. 4 is a cross-sectional view schematically showing a step of producing a resin sheet with a conductor layer in an example of a method for producing a laminated substrate according to Embodiment 1 of the present invention. FIG. 5 is a cross-sectional view schematically showing a step of producing another resin sheet with a conductor layer in an example of a method for producing a laminated substrate according to Embodiment 1 of the present invention. FIG. 6 is a cross-sectional view schematically showing a step of laminating resin sheets with conductor layers in an example of a method for producing a laminated substrate according to Embodiment 1 of the present invention. FIG. 7 is an example of a cross-sectional image showing an enlarged view of the laminated substrate according to Embodiment 1 of the present invention. FIG. 8 is a cross-sectional view for explaining a method for determining the average thickness, average aspect ratio, and average slope of the second resin material. FIG. 9 is an enlarged cross-sectional view schematically illustrating a state in which another example of the laminated substrate according to the first embodiment of the present invention is viewed at a second cross section. FIG. 10 is an enlarged cross-sectional view schematically illustrating a state in which yet another example of the laminated substrate according to the first embodiment of the present invention is viewed at a second cross section. FIG. 11 is a cross-sectional view schematically illustrating a state in which an example of the laminated substrate according to the second embodiment of the present invention is viewed at a second cross section. FIG. 12 is a cross-sectional view schematically illustrating a state in which an example of the laminated substrate according to the third embodiment of the present invention is viewed at a second cross section. FIG. 13 is a cross-sectional view schematically illustrating a state in which an example of the laminated substrate according to the fourth embodiment of the present invention is viewed at a second cross section. FIG. 14 is a cross-sectional view schematically illustrating a state in which an example of the laminated substrate according to the fifth embodiment of the present invention is viewed at a first cross section. FIG. 15 is a cross-sectional view schematically illustrating a state in which an example of the laminated substrate according to the sixth embodiment of the present invention is viewed at a first cross section.

[0009] The laminated substrate of the present invention will be described below. Note that the present invention is not limited to the following configurations and may be modified as appropriate within the scope of the present invention. In addition, a combination of multiple individual preferred configurations described below also constitutes the present invention.

[0010] The following embodiments are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. From embodiment 2 onwards, descriptions of matters common to embodiment 1 will be omitted, and differences will be mainly described. In particular, similar effects resulting from similar configurations will not be mentioned one after the other for each embodiment.

[0011] In the following description, when there is no need to particularly distinguish between the embodiments, they will simply be referred to as "the laminated substrate of the present invention."

[0012] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, scale, etc. may differ from those of the actual product.

[0013] In this specification, unless otherwise specified, terms indicating the relationship between elements (e.g., "parallel," "perpendicular," etc.) and terms indicating the shape of elements not only mean the literal strict form, but also mean a range that is substantially equivalent, for example, a range that includes a difference of about a few percent.

[0014] The laminated substrate of the present invention comprises: a first resin layer having a first main surface and a second main surface opposed to each other in a thickness direction; a second resin layer having a third main surface and a fourth main surface opposed to each other in the thickness direction, the fourth main surface being opposed to the first main surface; and a first conductor layer located between the first resin layer and the second resin layer and being in contact with the first main surface and the fourth main surface, wherein the first resin layer and the second resin layer each contain a first resin material made of a thermoplastic resin and a second resin material made of a thermoplastic resin and dispersed in the first resin material; If the melting point of the first resin material is Tm1 and the melting point of the second resin material is Tm2, ​​then Tm1 > Tm2; if, in a plane direction perpendicular to the thickness direction, the thermal expansion coefficient of the first resin material is CTE1, the thermal expansion coefficient of the second resin material is CTE2, and the thermal expansion coefficient of the first conductor layer is CTE3, then |CTE3-CTE2| > |CTE3-CTE1|; and when viewing a first cross section along the thickness direction, the abundance ratio of the second resin material at the interface between the first resin layer and the first conductor layer is 40% or more and 70% or less.

[0015] [Embodiment 1] Fig. 1 is a cross-sectional view schematically showing an example of a laminated substrate according to Embodiment 1 of the present invention, as viewed at a first cross section along the thickness direction. Fig. 2 is a cross-sectional view schematically showing an example of a laminated substrate according to Embodiment 1 of the present invention, as viewed at a second cross section perpendicular to the first cross section along the thickness direction.

[0016] The laminated substrate 1 shown in FIGS. 1 and 2 includes a first resin layer 10a, a second resin layer 10b, and a first conductor layer 20a.

[0017] 1, for example, when the first conductor layer 20a extends in a certain direction, the first cross section of the laminated substrate 1 is taken as a cross section of the laminated substrate 1 along the thickness direction (vertical direction in FIG. 1) of the laminated substrate 1 and the direction in which the first conductor layer 20a extends (horizontal direction in FIG. 1). Also, when the second cross section of the laminated substrate 1 shown in FIG. 2, for example, when the first conductor layer 20a extends in a certain direction, the second cross section of the laminated substrate 1 is taken as a cross section of the laminated substrate 1 along the thickness direction (vertical direction in FIG. 2) of the laminated substrate 1 and the direction perpendicular to the direction in which the first conductor layer 20a extends (horizontal direction in FIG. 2).

[0018] The first resin layer 10a has a first main surface 10aa and a second main surface 10ab that face each other in the thickness direction.

[0019] The second resin layer 10b has a third main surface 10ba and a fourth main surface 10bb that face each other in the thickness direction.

[0020] 2, the fourth main surface 10bb of the second resin layer 10b is in contact with the first main surface 10aa of the first resin layer 10a, except for the portion where the fourth main surface 10bb of the second resin layer 10b is in contact with the first conductor layer 20a.

[0021] The first resin layer 10a and the second resin layer 10b contain a first resin material 11a and a second resin material 11b, respectively.

[0022] The first resin material 11a is made of a thermoplastic resin.

[0023] Examples of thermoplastic resins that make up the first resin material 11a include liquid crystal polymer (LCP), thermoplastic polyimide (TPI), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK).

[0024] The first resin material 11a is preferably made of a liquid crystal polymer. Since liquid crystal polymers have a low relative dielectric constant among thermoplastic resins, when the first resin material 11a is made of a liquid crystal polymer, the dielectric properties in the high frequency range of the laminated substrate 1 are likely to be improved. Furthermore, since liquid crystal polymers have low hygroscopicity, when the first resin material 11a is made of a liquid crystal polymer, changes in the dielectric properties of the laminated substrate 1 due to moisture absorption are less likely to occur.

[0025] When the first resin material 11a is made of a liquid crystal polymer, the liquid crystal polymer constituting the first resin material 11a preferably contains a copolymer of p-hydroxybenzoic acid (HBA) and 6-hydroxy-2-naphthoic acid (HNA).

[0026] Copolymers of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid are generally referred to as type II wholly aromatic polyesters (also referred to as type 1.5 wholly aromatic polyesters). Type II wholly aromatic polyesters are less susceptible to hydrolysis than type III partially aromatic polyesters, and are therefore preferred as constituent materials for the laminate substrate 1. Furthermore, type II wholly aromatic polyesters have a low dielectric loss tangent due to the naphthalene ring, and therefore contribute to reducing electrical energy loss in the first resin layer 10a in the laminate substrate 1.

[0027] When the first resin material 11a is made of a liquid crystal polymer, the liquid crystal polymer constituting the first resin material 11a may further contain, in addition to the type II wholly aromatic polyester, a type I wholly aromatic polyester, or may further contain a type III partially aromatic polyester, or may further contain a type I wholly aromatic polyester and a type III partially aromatic polyester.

[0028] The structure (type) of each monomer constituting the liquid crystal polymer can be analyzed by reactive pyrolysis gas chromatography mass spectrometry (reactive pyrolysis GC-MS method).

[0029] The second resin material 11b is made of a thermoplastic resin.

[0030] Examples of thermoplastic resins that make up the second resin material 11b include perfluoroalkoxyalkane (PFA) (fluorine-containing resin), thermoplastic polyimide (TPI), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyphenylene ether (PPE), polymethylpentene (PMP), cross-linked polyethylene (XLPE), and polynorbornene (PNB).

[0031] The second resin material 11b is preferably made of perfluoroalkoxyalkane, thermoplastic polyimide, polyphenylene sulfide, polyether ether ketone, polyphenylene ether, polymethylpentene, cross-linked polyethylene, or polynorbornene.

[0032] More preferably, the second resin material 11b is made of perfluoroalkoxyalkane, polymethylpentene, or polynorbornene.

[0033] Because perfluoroalkoxyalkanes have a lower dielectric constant than liquid crystal polymers, when the second resin material 11b is made of a perfluoroalkoxyalkane, the dielectric properties in the high frequency range of the laminate substrate 1 are likely to be improved. Furthermore, because perfluoroalkoxyalkanes, like liquid crystal polymers, have low hygroscopicity, when the second resin material 11b is made of a perfluoroalkoxyalkane, changes in the dielectric properties of the laminate substrate 1 due to moisture absorption are less likely to occur. Furthermore, because perfluoroalkoxyalkanes have a high heat resistance temperature of 260°C or higher, when the second resin material 11b is made of a perfluoroalkoxyalkane, the laminate substrate 1 is less likely to be damaged, for example, when the laminate substrate 1 is incorporated into an electronic device by reflow soldering.

[0034] Since polymethylpentene has a low relative permittivity and dielectric loss tangent similar to perfluoroalkoxyalkanes, when the second resin material 11b is made of polymethylpentene, the dielectric properties of the laminate substrate 1 in the high frequency range are likely to be improved. Furthermore, since polymethylpentene has low hygroscopicity similar to perfluoroalkoxyalkanes, when the second resin material 11b is made of polymethylpentene, the dielectric properties of the laminate substrate 1 are less likely to change due to moisture absorption. Furthermore, since polymethylpentene has a smaller thermal expansion coefficient than perfluoroalkoxyalkanes, when the second resin material 11b is made of polymethylpentene, the dimensional changes of the laminate substrate 1 are less likely to occur. Furthermore, since polymethylpentene has a higher tensile strength (e.g., tensile elongation at break) than perfluoroalkoxyalkanes, when the second resin material 11b is made of polymethylpentene, the strength of the laminate substrate 1 is increased.

[0035] Since polynorbornene has a low relative permittivity and dielectric loss tangent, similar to perfluoroalkoxyalkanes, when the second resin material 11b is made of polynorbornene, the dielectric properties in the high frequency range of the laminated substrate 1 are likely to be improved. Furthermore, since polynorbornene has low hygroscopicity, similar to perfluoroalkoxyalkanes, when the second resin material 11b is made of polynorbornene, changes in the dielectric properties of the laminated substrate 1 due to moisture absorption are less likely to occur. Furthermore, since polynorbornene has a smaller thermal expansion coefficient than perfluoroalkoxyalkanes, when the second resin material 11b is made of polynorbornene, the dimensional changes of the laminated substrate 1 are less likely to occur. Furthermore, since polynorbornene has a higher tensile modulus than perfluoroalkoxyalkanes, when the second resin material 11b is made of polynorbornene, the bending rigidity of the laminated substrate 1 is increased.

[0036] The type of resin material present in the resin layer is identified as follows: First, the laminated substrate is polished to expose a cross section (e.g., a first cross section) along the thickness direction. Then, the cross section of the laminated substrate is analyzed using a microscopic Fourier transform infrared spectrophotometer (microscopic FT-IR), thereby identifying the type of resin material present in the resin layer.

[0037] The second resin material 11b is dispersed in the first resin material 11a, so that the second resin material 11b functions as a filler for the first resin material 11a and is easily bound by the first resin material 11a.

[0038] The first resin layer 10a and the second resin layer 10b may each further contain a material (e.g., a resin material) other than the first resin material 11a and the second resin material 11b. In this case, for example, the content of the first resin material 11a is the largest in each of the first resin layer 10a and the second resin layer 10b, and the content of the second resin material 11b is the next largest. The content of the resin material is determined, for example, by using image analysis software to measure the area ratio of the resin material in a cross-sectional image (e.g., an image of the first cross-section) along the thickness direction of the resin layer.

[0039] The thicknesses of the first resin layer 10a and the second resin layer 10b may be the same as or different from each other.

[0040] The first conductor layer 20a is located between the first resin layer 10a and the second resin layer 10b and is provided so as to be in contact with the first main surface 10aa of the first resin layer 10a and the fourth main surface 10bb of the second resin layer 10b. As such, no other layer, such as an adhesive layer, is provided between the first resin layer 10a and the first conductor layer 20a, or between the second resin layer 10b and the first conductor layer 20a.

[0041] The first conductor layer 20a is preferably provided across the interface between the first resin layer 10a and the second resin layer 10b. This allows the interface between the first resin layer 10a and the first conductor layer 20a and the interface between the second resin layer 10b and the first conductor layer 20a to be shifted in the thickness direction from the interface between the first resin layer 10a and the second resin layer 10b, thereby suppressing peeling at the interface between the first resin layer 10a and the first conductor layer 20a and the interface between the second resin layer 10b and the first conductor layer 20a.

[0042] 2 shows the interface between the first resin layer 10a and the second resin layer 10b, but in reality, this interface does not have to be clearly visible. When the interface between the first resin layer 10a and the second resin layer 10b is not clearly visible, in the second cross section along the thickness direction as shown in FIG. 2, a plane passing through the center in the thickness direction of the cross section of the first conductor layer 20a and extending along a plane direction perpendicular to the thickness direction (the left-right direction in FIG. 2) is regarded as the interface between the first resin layer 10a and the second resin layer 10b.

[0043] The first conductor layer 20a may be a surface extending over the entire first main surface 10aa of the first resin layer 10a or the fourth main surface 10bb of the second resin layer 10b, or may have a pattern shape patterned into wiring or the like on a portion of the first main surface 10aa of the first resin layer 10a or the fourth main surface 10bb of the second resin layer 10b.

[0044] Examples of materials that can be used to form the first conductor layer 20a include copper, silver, aluminum, stainless steel, nickel, gold, and alloys containing at least one of these metals.

[0045] The first conductor layer 20a is made of, for example, a metal foil, and is preferably made of copper foil among other metal foils. In this case, metals other than copper may be present on the surface of the copper foil.

[0046] The thickness of the first conductor layer 20a is preferably 1 μm or more and 35 μm or less, and more preferably 6 μm or more and 18 μm or less.

[0047] In the laminated substrate 1, when the melting point of the first resin material 11a is Tm1 and the melting point of the second resin material 11b is Tm2, ​​Tm1>Tm2.

[0048] The melting point of the resin material present in the resin layer is determined as follows. First, the conductor layer is removed from the laminate substrate by peeling, etching, or another method to extract the resin layer. Then, the target resin material (e.g., the first resin material or the second resin material) is extracted from the resin layer by scraping or another method. Thereafter, the melting point of the target resin material is measured using a differential scanning calorimeter (DSC). Note that, if the melting point of the target resin material cannot be clearly measured using the above-mentioned method, or if the target resin material is an amorphous resin material, the glass transition temperature (Tg) may be used instead.

[0049] In the laminated substrate 1, in the planar direction perpendicular to the thickness direction, if the thermal expansion coefficient of the first resin material 11a is CTE1, the thermal expansion coefficient of the second resin material 11b is CTE2, and the thermal expansion coefficient of the first conductor layer 20a is CTE3, then |CTE3-CTE2|>|CTE3-CTE1|.

[0050] It is preferable that CTE1<CTE2 in the laminate substrate 1. In this case, the difference between CTE1 and CTE2 is preferably 20 ppm / °C or more and 120 ppm / °C or less.

[0051] It is preferable that CTE1<CTE3 in the laminate substrate 1. In this case, the difference between CTE1 and CTE3 is preferably 2 ppm / °C or more and 10 ppm / °C or less.

[0052] It is preferable that CTE2>CTE3 in the laminate substrate 1. In this case, the difference between CTE2 and CTE3 is preferably 30 ppm / °C or more and 110 ppm / °C or less.

[0053] When the first conductor layer 20a is made of copper foil, CTE3 is approximately 16 ppm / °C.

[0054] The thermal expansion coefficient of the resin material present in the resin layer in the in-plane direction is determined as follows. First, a target resin layer (e.g., a first resin layer) is extracted from the laminate substrate by removing the conductor layer or the like using a method such as peeling or etching. Then, the thermal expansion coefficient of the target resin layer in the in-plane direction is measured using thermomechanical analysis (TMA). For example, a 20 mm long x 4 mm wide resin layer sample is cut out. The sample is heated and then cooled under the following measurement conditions: a tensile mode, a chuck distance of 10 mm, a load of 5 g, a heating rate of 40°C / min, and a cooling rate of 10°C / min. The change in the chuck distance during the cooling process is measured over a temperature range from 100°C to 50°C, thereby determining the thermal expansion coefficient of the target resin layer sample in the in-plane direction. Next, the elastic modulus of the target resin layer sample is measured using dynamic mechanical analysis (DMA) in the tensile mode. Meanwhile, the type of resin material present in the target resin layer sample is identified for a cross section (e.g., a first cross section) along the thickness direction of the target resin layer sample using the above-described method. Then, for example, using image analysis software, the area proportion of the target resin material (e.g., the first resin material or the second resin material) in the cross section of the target resin layer sample is measured. Furthermore, the elastic modulus of the target resin material in the cross section of the target resin layer sample is measured using the elastic modulus measurement mode of a scanning probe microscope (SPM). Based on the measurement data obtained as described above, the thermal expansion coefficient of the target resin material in the in-plane direction is calculated from the thermal expansion coefficient of the target resin layer sample in the in-plane direction according to the area proportion and elastic modulus of the target resin material.For example, in the case of using a sample of the first resin layer 10a containing the first resin material 11a and the second resin material 11b, the thermal expansion coefficient in the plane direction of the first resin material 11a is CTE1 (unit: ppm / °C), the thermal expansion coefficient in the plane direction of the second resin material 11b is CTE2 (unit: ppm / °C), the thermal expansion coefficient in the plane direction of the sample of the first resin layer 10a is CTEt (unit: ppm / °C), the elastic modulus of the first resin material 11a is E1 (unit: GPa), the elastic modulus of the second resin material 11b is E2 (unit: GPa), the elastic modulus of the sample of the first resin layer 10a is Et (unit: GPa), the area ratio of the first resin material 11a is V1 (unit: %), and the area ratio of the second resin material 11b is V2 (unit: %), then the following formula (A) holds as a stress-neutral relationship. CTE1×E1×V1+CTE2×E2×V2=CTEt×Et×(V1+V2) (A) Here, CTEt, E1, E2, Et, V1, and V2 are measured by the method described above. Furthermore, CTE2 is measured by the following method. First, the sample of the first resin layer 10a is treated with a strong alkali to remove the first resin material 11a from the sample of the first resin layer 10a. Then, the second resin material 11b (a mass of multiple irregular shapes) taken out of the sample of the first resin layer 10a is subjected to hot pressing (pressure, for example, 2 MPa or more and 3 MPa or less) at a temperature 20°C lower than the melting point of the second resin material 11b and lower than the melting point of the second resin material 11b (i.e., (Tm2-20) or more and Tm2 or less), to produce a resin sheet made of the second resin material 11b with a thickness of 50 μm or more and 500 μm or less. Thereafter, the thermal expansion coefficient CTE2 in the plane direction of the resin sheet made of the second resin material 11b is measured by thermomechanical analysis. Using the CTE2, CTEt, E1, E2, Et, V1, and V2 obtained as described above, CTE1 is calculated from the following formula (B), which is obtained by modifying the above formula (A). CTE1=[CTEt×Et×(V1+V2)−CTE2×E2×V2] / [E1×V1] (B).

[0055] The thermal expansion coefficient of a conductor layer in the planar direction is determined as follows. First, a target conductor layer is removed from a laminate substrate by peeling or other methods. Then, the thermal expansion coefficient of the target conductor layer in the planar direction is measured by thermomechanical analysis. When measuring the thermal expansion coefficient of the conductor layer in the planar direction, the same measurement conditions are used as when measuring the thermal expansion coefficient of the resin layer in the planar direction, for example.

[0056] In the laminated substrate 1, when viewing a first cross section along the thickness direction as shown in FIG. 1, the abundance ratio of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a (hereinafter also referred to as "the abundance ratio of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a") is 40% or more and 70% or less.

[0057] The content of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is determined as follows.

[0058] Figure 3 is a cross-sectional view schematically showing an enlarged portion of the laminated substrate shown in Figure 1, and is a cross-sectional view for explaining a method of determining the presence ratio of the second resin material at the interface between the first resin layer and the first conductor layer.

[0059] First, the laminate substrate 1 is polished to expose a first cross section along the thickness direction, as shown in FIG. 1 . Next, the first cross section of the laminate substrate 1 is imaged at a magnification of 500x using a scanning electron microscope (SEM). At this time, as shown in FIG. 3 , the imaging range is set to a range including at least a portion of the interface between the first resin layer 10a and the first conductor layer 20a, with a dimension K in the thickness direction of 100 μm and a dimension L in the plane direction of 200 μm. The interface between the first resin layer 10a and the first conductor layer 20a can be confirmed using the scanning electron microscope. Then, in the obtained cross-sectional image of the laminate substrate 1, for each of the second resin materials 11b present at the interface between the first resin layer 10a and the first conductor layer 20a, the plane dimension of the portion (exposed portion) in contact with the interface between the first resin layer 10a and the first conductor layer 20a (the main surface of the first conductor layer 20a facing the first resin layer 10a) is determined. In the example shown in Figure 3, there are six second resin materials 11b present at the interface between the first resin layer 10a and the first conductor layer 20a, and for each of these six second resin materials 11b, dimensions L1, L2, L3, L4, L5, and L6 in the surface direction of the portion (exposed portion) that contacts the interface between the first resin layer 10a and the first conductor layer 20a (the main surface of the first conductor layer 20a facing the first resin layer 10a) are determined. Then, 100 × "the sum of the dimensions in the planar direction of the portion of the second resin material 11b that is in contact with the interface between the first resin layer 10a and the first conductor layer 20a (the main surface of the first conductor layer 20a on the first resin layer 10a side)" / "the dimension L in the planar direction of the imaging range", or in the example shown in Figure 3, 100 × (L1 + L2 + L3 + L4 + L5 + L6) / L is calculated, and this is defined as the abundance ratio (unit: %) of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a.

[0060] In the laminate substrate 1, Tm1 > Tm2, ​​|CTE3 - CTE2| > |CTE3 - CTE1|, and the proportion of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is 40% or more and 70% or less, thereby realizing a laminate substrate with excellent adhesion between the first resin layer 10a and the first conductor layer 20a and suppressed warpage. The mechanism by which the laminate substrate 1 achieves the above effects will be described below, showing an example of a method for manufacturing the laminate substrate 1.

[0061] The laminated substrate 1 is manufactured, for example, as follows.

[0062] <Step of Producing Resin Sheet with Conductor Layer> FIG. 4 is a cross-sectional view schematically showing a step of producing a resin sheet with a conductor layer in an example of the method for producing the laminated substrate according to the first embodiment of the present invention.

[0063] First, a resin composition is prepared by blending the first resin material 11 a and the second resin material 11 b. For example, the first resin material 11 a and the second resin material 11 b are finely pulverized and then dispersed in a dispersion medium to prepare a paste or slurry-like resin composition. Examples of the dispersion medium include butanediol, water, ethanol, and a mixture containing at least two of these.

[0064] Next, a first resin sheet 110a containing a first resin material 11a and a second resin material 11b is produced using the resin composition. At this time, the first resin sheet 110a is produced by, for example, a method of applying the resin composition and then drying it (to evaporate the dispersion medium), a method of making the resin composition into paper and then drying it (to evaporate the dispersion medium), or the like.

[0065] In this specification, the term "sheet" is synonymous with "film," and the two are not distinguished by thickness.

[0066] Next, a first resin sheet 110a having a first main surface 110aaa and a second main surface 110ab opposed to each other in the thickness direction is fabricated, and a conductor layer 20x is adjacent to the second main surface 110ab side of the first resin sheet 110a, thereby fabricating a first resin sheet 210a with a conductor layer as shown in Fig. 4. In this case, for example, the conductor layer 20x is pressure-bonded to the second main surface 110ab of the first resin sheet 110a, thereby fabricating the first resin sheet 210a with a conductor layer.

[0067] When the conductor layer 20x is pressure-bonded to the first resin sheet 110a, for example, a laminate of the first resin sheet 110a and the conductor layer 20x is heated and pressed in the thickness direction, thereby performing a hot press process. The temperature during the hot press process is preferably equal to or higher than the melting point of the second resin material 11b and equal to or lower than the melting point of the first resin material 11a (i.e., equal to or higher than Tm2 and equal to or lower than Tm1), and more preferably equal to or higher than the melting point of the second resin material 11b and equal to or lower than a temperature 10°C lower than the melting point of the first resin material 11a (i.e., equal to or higher than Tm2 and equal to or lower than (Tm1-10)). In this case, the temperature rise rate during the hot press process is preferably equal to or higher than 5°C / min, and more preferably equal to or higher than 5°C / min and equal to or lower than 50°C / min. When the heat press processing is performed under the above-mentioned temperature conditions, for example, the second resin material 11b melts and connects in the surface direction, as shown in Figure 4, making it easier to form a flat shape (layer) along the surface direction, and furthermore, it is easier to exist in a flat shape on the first main surface 110aa of the first resin sheet 110a.

[0068] The conductor layer 20x may be patterned by etching after being pressure-bonded to the first resin sheet 110a.

[0069] FIG. 5 is a cross-sectional view schematically showing a step of producing another resin sheet with a conductor layer in an example of the method for producing the laminated substrate according to the first embodiment of the present invention.

[0070] In a similar manner to the method for producing the first resin sheet 210a with a conductor layer, a second resin sheet 110b with a conductor layer is produced, in which the second resin sheet 110b has a third main surface 110ba and a fourth main surface 110bb that face each other in the thickness direction, and the first conductor layer 20a is adjacent to the fourth main surface 110bb side, as shown in Fig. 5. In this case, when a hot press process is performed on the laminate of the second resin sheet 110b and the first conductor layer 20a under the above-mentioned temperature conditions, as shown in Fig. 5, the second resin material 11b melts and connects in the surface direction, making it easier to form a flat shape (layer) along the surface direction, and furthermore, it is easier to exist in a flat shape on the third main surface 110ba of the second resin sheet 110b.

[0071] <Step of Laminating Resin Sheets with Conductor Layers> FIG. 6 is a cross-sectional view that schematically shows a step of laminating resin sheets with conductor layers in an example of the method for producing the laminated substrate according to the first embodiment of the present invention.

[0072] As shown in Fig. 6, the first resin sheet 210a with a conductor layer and the second resin sheet 210b with a conductor layer are laminated in the thickness direction. Specifically, the first resin sheet 210a with a conductor layer and the second resin sheet 210b with a conductor layer are laminated in the thickness direction so that the surface of the first resin sheet 210a with a conductor layer facing the first resin sheet 110a contacts the surface of the second resin sheet 210b with a conductor layer facing the first conductor layer 20a. Note that, for ease of explanation, Fig. 6 shows the resin sheets with conductor layers spaced apart from each other.

[0073] The obtained laminate is then subjected to a hot press process by applying heat and pressure in the thickness direction, thereby bonding the first resin sheet 210a with the conductor layer and the second resin sheet 210b with the conductor layer together, and the first resin sheet 110a and the second resin sheet 110b become the first resin layer 10a and the second resin layer 10b, respectively.

[0074] The temperature during the hot press processing is preferably equal to or higher than the melting point of the second resin material 11b and equal to or lower than the melting point of the first resin material 11a (i.e., equal to or higher than Tm2 and equal to or lower than Tm1), and more preferably equal to or higher than the melting point of the second resin material 11b and equal to or lower than a temperature 10°C lower than the melting point of the first resin material 11a (i.e., equal to or higher than Tm2 and equal to or lower than (Tm1-10)). In this case, the temperature rise rate during the hot press processing is preferably equal to or higher than 5°C / min, and more preferably equal to or higher than 5°C / min and equal to or lower than 50°C / min. When the hot press processing is performed under the above temperature conditions, for example, as shown in FIG. 6, the second resin material 11b can be present at the interface between the first resin layer 10a and the first conductor layer 20a at a ratio of 40% to 70% while maintaining a flat shape along the surface direction.

[0075] As described above, since Tm1>Tm2, when the first resin sheet 210a with a conductor layer and the second resin sheet 210b with a conductor layer are pressure-bonded together, the hot press processing can be performed at a temperature equal to or higher than Tm2 and equal to or lower than Tm1.

[0076] When the hot press processing is performed at a temperature equal to or higher than Tm2, ​​the fluidity of the second resin material 11b present at (or near) the interface between the first resin layer 10a and the first conductor layer 20a is increased, thereby shortening the distance between the second resin material 11b in the first resin layer 10a and the first conductor layer 20a. Since the proportion of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is 40% or more, the adhesion between the second resin material 11b in the first resin layer 10a and the first conductor layer 20a is enhanced. As a result, the adhesion between the first resin layer 10a and the first conductor layer 20a is excellent.

[0077] On the other hand, when the hot press processing is performed at a temperature equal to or lower than Tm1, the fluidity of the first resin material 11a is not increased, and therefore the aggregation of the second resin material 11b is suppressed by the first resin material 11a, and as a result, the second resin material 11b can be maintained in a flat shape along the surface direction.

[0078] Furthermore, since |CTE3-CTE2|>|CTE3-CTE1| as described above, hot-press processing can be performed in a state in which the thermal expansion coefficient of the first resin material 11a in the plane direction is closer to the thermal expansion coefficient of the first conductor layer 20a in the plane direction than the thermal expansion coefficient of the second resin material 11b in the plane direction. In other words, hot-press processing can be performed in a state in which the first resin material 11a is less susceptible to dimensional change relative to the first conductor layer 20a than the second resin material 11b. At this time, because the abundance ratio of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is 70% or less, dimensional change of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is suppressed by the first resin material 11a, which is less susceptible to dimensional change relative to the first conductor layer 20a. As a result, the thermal expansion coefficient in the planar direction of the first resin layer 10a, which contains the first resin material 11a and the second resin material 11b, approaches the thermal expansion coefficient in the planar direction of the first conductor layer 20a, thereby suppressing warping caused by the difference in the thermal expansion coefficients in the planar direction of the first resin layer 10a and the first conductor layer 20a, i.e., the difference in dimensional change between the first resin layer 10a and the first conductor layer 20a.

[0079] Subsequently, after the hot press processing is performed, the conductor layer 20x is removed by a method such as peeling, etching, etc. The conductor layer 20x may be removed before the hot press processing is performed.

[0080] In this manner, the laminated substrate 1 shown in FIG. 1 is manufactured.

[0081] FIG. 7 is an example of an enlarged cross-sectional image of the multilayer substrate according to the first embodiment of the present invention.

[0082] In the cross-sectional image of the laminated substrate 1 shown in FIG. 7, it was confirmed that the proportion of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a was 40% or more and 70% or less.

[0083] From the viewpoint of achieving excellent adhesion between the first resin layer 10a and the first conductor layer 20a, the abundance ratio of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is preferably 50% or more and 70% or less. Furthermore, from the viewpoint of suppressing warpage of the laminated substrate 1, the abundance ratio of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is preferably 40% or more and 60% or less. Therefore, from the viewpoint of achieving excellent adhesion between the first resin layer 10a and the first conductor layer 20a and suppressing warpage of the laminated substrate 1, the abundance ratio of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is preferably 50% or more and 60% or less.

[0084] In the laminate substrate 1, when viewed from the first cross section, the abundance ratio of the second resin material 11b at the interface between the second resin layer 10b and the first conductor layer 20a (hereinafter also referred to as the "abundance ratio of the second resin material 11b at the interface between the second resin layer 10b and the first conductor layer 20a") is preferably 40% or more and 70% or less. From the viewpoint of achieving excellent adhesion between the second resin layer 10b and the first conductor layer 20a, the abundance ratio of the second resin material 11b at the interface between the second resin layer 10b and the first conductor layer 20a is more preferably 50% or more and 70% or less. Furthermore, from the viewpoint of suppressing warpage of the laminate substrate 1, the abundance ratio of the second resin material 11b at the interface between the second resin layer 10b and the first conductor layer 20a is more preferably 40% or more and 60% or less. Therefore, from the viewpoint of achieving excellent adhesion between the second resin layer 10b and the first conductor layer 20a and suppressing warping of the laminated substrate 1, it is more preferable that the proportion of the second resin material 11b at the interface between the second resin layer 10b and the first conductor layer 20a be 50% or more and 60% or less.

[0085] In the laminate substrate 1, when viewed from the first cross section, the average thickness of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is preferably 5 μm or less. In this case, the thickness of the second resin material 11b, which is prone to dimensional change relative to the first conductor layer 20a, is reduced at the interface between the first resin layer 10a and the first conductor layer 20a, and the first resin material 11a tends to suppress dimensional change of the second resin material 11b. As a result, the first resin layer 10a containing the first resin material 11a and the second resin material 11b has excellent dimensional stability.

[0086] In the laminate substrate 1, when viewed from the first cross section, the average thickness of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is preferably 1 μm or more.

[0087] In the laminate substrate 1, when viewed from the first cross section, the average aspect ratio of the second resin material 11b is preferably 3 or greater. In this case, even if tensile stress is applied to the laminate substrate 1 by pulling the laminate substrate 1, the tensile stress is less likely to concentrate at the interface between the first resin material 11a and the second resin material 11b, making it less likely that cracks will originate at the interface between the first resin material 11a and the second resin material 11b. Furthermore, even if bending stress is applied to the laminate substrate 1 by bending the laminate substrate 1, the bending stress is less likely to concentrate at the interface between the first resin material 11a and the second resin material 11b, making it less likely that cracks will originate at the interface between the first resin material 11a and the second resin material 11b. As a result, the laminate substrate 1 has excellent tensile resistance and bending resistance.

[0088] In the laminated substrate 1, when viewed from the first cross section, the average aspect ratio of the second resin material 11b is preferably 50 or less.

[0089] In the laminate substrate 1, when viewed from the first cross section, the average inclination of the second resin material 11b with respect to the surface direction (hereinafter also referred to as the "average inclination of the second resin material 11b") is preferably 15° or less. In this case, even if tensile stress is applied to the laminate substrate 1 by pulling the laminate substrate 1, the tensile stress is less likely to concentrate at the interface between the first resin material 11a and the second resin material 11b, making it less likely that cracks will originate at the interface between the first resin material 11a and the second resin material 11b. Furthermore, even if bending stress is applied to the laminate substrate 1 by bending the laminate substrate 1, the bending stress is less likely to concentrate at the interface between the first resin material 11a and the second resin material 11b, making it less likely that cracks will originate at the interface between the first resin material 11a and the second resin material 11b. As a result, the laminate substrate 1 has excellent tensile resistance and bending resistance.

[0090] In the laminated substrate 1, when the first cross section is viewed, the average inclination of the second resin material 11b with respect to the plane direction may be 0° or more.

[0091] In the laminate substrate 1, when viewed from the first cross section, it is more preferable that the average aspect ratio of the second resin material 11b is 3 or more and the average inclination of the second resin material 11b relative to the surface direction is 15° or less. In this embodiment, the second resin material 11b is said to have a flat shape along the surface direction. When the second resin material 11b has a flat shape along the surface direction, even if tensile stress is applied to the laminate substrate 1 in the surface direction, the number of crack initiation points at the interface between the first resin material 11a and the second resin material 11b, which have different elastic moduli (e.g., Young's modulus) in the surface direction, is likely to be reduced. As a result, the tensile resistance of the laminate substrate 1 is improved.

[0092] The average thickness, average aspect ratio, and average inclination of the second resin material 11b are determined as follows.

[0093] FIG. 8 is a cross-sectional view for explaining a method for determining the average thickness, average aspect ratio, and average inclination of the second resin material.

[0094] First, a method for determining the average thickness of the second resin material 11b will be described. A cross-sectional image (image area: 100 μm (thickness direction) × 200 μm (surface direction)) of the laminate substrate 1 taken when determining the abundance ratio of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is used to draw a rectangle P with the minimum area circumscribing the second resin material 11b, as shown in FIG. 8, using image analysis software. In this case, the rectangle P is assumed to be composed of a short side P1 extending in the thickness direction and a long side P2 extending in the surface direction. The dimension of the short side P1 of the rectangle P is then measured, and this is defined as the thickness of the second resin material 11b. In this way, the thickness of each of 50 or more second resin material particles 11b present on the first main surface 10aa of the first resin layer 10a is measured in the cross-sectional image of the laminate substrate 1, and the average value of these measurements is defined as the average thickness of the second resin material 11b.

[0095] Next, a method for determining the average aspect ratio of the second resin material 11b will be described. A cross-sectional image (image area: 100 μm (thickness direction) × 200 μm (plane direction)) of the laminate substrate 1 taken when determining the abundance ratio of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is used to draw an ellipse Q with the smallest area circumscribing the second resin material 11b using image analysis software, as shown in FIG. 8 . Then, the dimension of the major axis Q2 / the dimension of the minor axis Q1 of the ellipse Q is measured, and this is defined as the aspect ratio of the second resin material 11b. In this way, the aspect ratios of 50 or more second resin materials 11b are measured in the cross-sectional image of the laminate substrate 1, and the average value of these values ​​is defined as the average aspect ratio of the second resin material 11b.

[0096] Finally, a method for determining the average tilt of the second resin material 11b will be described. A cross-sectional image (image area: 100 μm (thickness direction) × 200 μm (plane direction)) of the laminate substrate 1 taken when determining the abundance ratio of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a is used to draw an ellipse Q with the smallest area circumscribing the second resin material 11b using image analysis software, as shown in FIG. 8 . Then, the angle θ of the major axis Q2 of the ellipse Q relative to the plane direction is measured, and this angle is defined as the tilt of the second resin material 11b. In this way, the tilt of each of 50 or more second resin materials 11b is measured in the cross-sectional image of the laminate substrate 1, and the average value of these is defined as the average tilt of the second resin material 11b.

[0097] In the laminate substrate 1, when viewed in a second cross section perpendicular to the first cross section along the thickness direction, the second resin material 11b is preferably in contact with a portion of the main surface of the first conductor layer 20a facing the first resin layer 10a. In this case, even if the elastic modulus (e.g., Young's modulus) of the second resin material 11b is low, that is, even if the second resin material 11b is easily deformed by an external force, the first conductor layer 20a is less likely to shift due to an external force than when the second resin material 11b is in contact with the entire main surface of the first conductor layer 20a facing the first resin layer 10a.

[0098] In the example shown in Figure 2, the second resin material 11b is in contact with a portion of the main surface of the first conductor layer 20a facing the first resin layer 10a, except for both ends of the main surface of the first conductor layer 20a facing the first resin layer 10a, but other configurations may also be used.

[0099] FIG. 9 is an enlarged cross-sectional view schematically illustrating another example of the laminated substrate according to the first embodiment of the present invention, as viewed from the second cross section.

[0100] In the example shown in FIG. 9, the second resin material 11b is in contact with one end of the main surface of the first conductor layer 20a on the first resin layer 10a side.

[0101] FIG. 10 is an enlarged cross-sectional view schematically illustrating a state in which still another example of the laminated substrate according to the first embodiment of the present invention is viewed from the second cross section.

[0102] In the example shown in FIG. 10, the second resin material 11b contacts both ends of the main surface of the first conductor layer 20a on the first resin layer 10a side.

[0103] In the laminated substrate 1, when the relative dielectric constant of the first resin material 11a is Dk1 and the relative dielectric constant of the second resin material 11b is Dk2, it is preferable that Dk1>Dk2.

[0104] The dielectric constant of the resin material present in the resin layer is determined as follows. For example, when a first resin layer 10a containing a first resin material 11a and a second resin material 11b is used as a sample, the first resin layer 10a is first treated with a strong alkali to extract the second resin material 11b. The extracted second resin material 11b is then molded into a sheet having a thickness of 50 μm or more and 500 μm or less to obtain a resin sheet sample. The dielectric constant of the second resin material 11b is then measured by a dielectric resonator method (TE011 mode, frequency range: 12 GHz or more and 60 GHz or less). Next, the dielectric constant of the first resin layer 10a is measured by the dielectric resonator method under the same conditions as above. Furthermore, an X-ray CT scanner is used to identify the three-dimensional structure of the first resin material 11a and the second resin material 11b in the first resin layer 10a, and then analysis software is used to measure the volume ratio of the first resin material 11a and the second resin material 11b in the first resin layer 10a. Then, from the relative dielectric constants of the first resin layer 10a and the second resin material 11b measured by the above-mentioned method, the relative dielectric constant of the first resin material 11a is calculated according to the volume ratio of the first resin material 11a and the second resin material 11b in the first resin layer 10a.

[0105] In the laminated substrate 1, when the dielectric loss tangent of the first resin material 11a is Df1 and the dielectric loss tangent of the second resin material 11b is Df2, it is preferable that Df1>Df2.

[0106] The dielectric loss tangent of the resin material present in the resin layer is determined as follows. For example, when a first resin layer 10a containing a first resin material 11a and a second resin material 11b is used as a sample, the first resin layer 10a is first treated with a strong alkali to extract the second resin material 11b. The extracted second resin material 11b is then molded into a sheet having a thickness of 50 μm or more and 500 μm or less to obtain a resin sheet sample. The dielectric loss tangent of the second resin material 11b is then measured by a dielectric resonator method (TE011 mode, frequency range: 12 GHz or more and 60 GHz or less). Next, the dielectric loss tangent of the first resin layer 10a is measured by the dielectric resonator method under the same conditions as above. Furthermore, an X-ray CT scanner is used to identify the three-dimensional structure of the first resin material 11a and the second resin material 11b in the first resin layer 10a, and then analysis software is used to measure the volume ratio of the first resin material 11a and the second resin material 11b in the first resin layer 10a. Then, from the dielectric loss tangent of the first resin layer 10a and the dielectric loss tangent of the second resin material 11b measured by the above-mentioned method, the dielectric loss tangent of the first resin material 11a is calculated according to the volume ratio of the first resin material 11a and the second resin material 11b in the first resin layer 10a.

[0107] In the laminated substrate 1, the adhesion (e.g., tensile elongation at break) between the second resin materials 11b is preferably higher than the adhesion (e.g., tensile elongation at break) between the first resin materials 11a. In this case, the adhesion strength between the resin layers of the laminated substrate 1 is likely to be improved.

[0108] The magnitude relationship of the adhesion (e.g., tensile elongation at break) between resin materials of the same type present in a resin layer is determined as follows. First, a tensile stress is applied to the resin layer by pulling the resin layer in a laminated substrate. At this time, for example, after removing the resin layer from the laminated substrate, a tensile test of the resin layer is performed in accordance with "JIS K 7127-1999." Then, when tensile stress is applied to the resin layer, it is confirmed which resin material breaks first. At this time, if the first resin material 11a breaks before the second resin material 11b breaks, it is determined that the adhesion (e.g., tensile elongation at break) between the second resin materials 11b is higher than the adhesion (e.g., tensile elongation at break) between the first resin materials 11a.

[0109] The laminated substrate 1 is used as, for example, a circuit board.

[0110] When the laminated substrate 1 is used as a circuit board, the laminated substrate 1 may have the first conductor layer 20a as a signal line for transmitting a signal, thereby forming a transmission line.

[0111] When the laminated substrate 1 has a first conductor layer 20a as a signal line for transmitting signals and forms a transmission line, if Dk1 > Dk2 as described above, coupled with the presence ratio of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a being 40% or more and 70% or less, the high-frequency characteristics of the laminated substrate 1 will be excellent.

[0112] When the laminated substrate 1 has the first conductor layer 20a as a signal line for transmitting signals and forms a transmission line, if Df1 > Df2 as described above, coupled with the presence ratio of the second resin material 11b at the interface between the first resin layer 10a and the first conductor layer 20a being 40% or more and 70% or less, the laminated substrate 1 will have excellent transmission loss characteristics.

[0113] When the laminated substrate of the present invention forms a transmission line, the laminated substrate of the present invention may form, for example, a stripline transmission line, a microstrip transmission line, a coplanar transmission line, or the like. The configurations of these transmission lines will be described below. Note that, in the following FIGS. 11, 12, and 13 illustrating the configurations of these transmission lines, the laminated substrate is shown as viewed from a second cross section (a cross section of the laminated substrate along the thickness direction of the laminated substrate and the direction perpendicular to the extension direction of the first conductor layer), similar to FIG. 2 and the like, in order to make the configurations of the transmission lines easier to understand.

[0114] Second Embodiment A laminated substrate according to a second embodiment of the present invention constitutes a stripline type transmission line.

[0115] FIG. 11 is a cross-sectional view schematically illustrating an example of the laminated substrate according to the second embodiment of the present invention, as viewed from the second cross section.

[0116] The laminated substrate 2 shown in Figure 11 has a first resin layer 10a, a second resin layer 10b, a third resin layer 10c, a fourth resin layer 10d, a first conductor layer 20a, a second conductor layer 20b, and a third conductor layer 20c.

[0117] The laminated substrate 2 has the same configuration as the laminated substrate 1, except that it is provided with a third resin layer 10c, a fourth resin layer 10d, a second conductor layer 20b, and a third conductor layer 20c.

[0118] The third resin layer 10c has a fifth main surface 10ca and a sixth main surface 10cb that face each other in the thickness direction.

[0119] 11 , the fifth main surface 10ca of the third resin layer 10c faces the second main surface 10ab of the first resin layer 10a. In the example shown in FIG. 11 , the fifth main surface 10ca of the third resin layer 10c contacts the second main surface 10ab of the first resin layer 10a.

[0120] The third resin layer 10c preferably contains the first resin material 11a and the second resin material 11b. Furthermore, in the laminate substrate 2, when viewed in a cross section along the thickness direction, the abundance ratio of the second resin material 11b on the fifth main surface 10ca of the third resin layer 10c is preferably 40% or more and 70% or less. In this case, when manufacturing the laminate structure of the first resin layer 10a and the third resin layer 10c by hot pressing, similar to the mechanism described above, the fluidity of the second resin material 11b present near the fifth main surface 10ca of the third resin layer 10c is increased, and this, combined with the shortened distance between the second resin material 11b in the first resin layer 10a and the second resin material 11b in the third resin layer 10c, results in excellent adhesion between the first resin layer 10a and the third resin layer 10c. Furthermore, similar to the mechanism described above, during the hot press processing, the dimensional change of the second resin material 11b is suppressed by the first resin material 11a, which is resistant to dimensional change, at the fifth main surface 10ca of the third resin layer 10c, thereby suppressing warpage due to dimensional change of the third resin layer 10c. Note that the fifth main surface 10ca of the third resin layer 10c, in this case the interface between the first resin layer 10a and the third resin layer 10c, can be easily confirmed using a fluorescence microscope in addition to a scanning electron microscope.

[0121] In the example shown in Figure 11, when looking at the second cross section as an example of a cross section along the thickness direction, the presence ratio of the second resin material 11b on the fifth main surface 10ca of the third resin layer 10c is shown to be 40% or more and 70% or less. However, when looking at the first cross section perpendicular to the second cross section as an example of a cross section along the thickness direction, the presence ratio of the second resin material 11b on the fifth main surface 10ca of the third resin layer 10c may also be 40% or more and 70% or less.

[0122] The fourth resin layer 10d has a seventh main surface 10da and an eighth main surface 10db that face each other in the thickness direction.

[0123] 11 , the eighth principal surface 10db of the fourth resin layer 10d faces the third principal surface 10ba of the second resin layer 10b.

[0124] The fourth resin layer 10d preferably contains the first resin material 11a and the second resin material 11b. Furthermore, in the laminate substrate 2, when viewed in a cross section along the thickness direction, the abundance ratio of the second resin material 11b on the eighth main surface 10db of the fourth resin layer 10d is preferably 40% or more and 70% or less. In this case, when manufacturing the laminate structure of the second resin layer 10b and the fourth resin layer 10d by hot pressing, similar to the mechanism described above, the fluidity of the second resin material 11b present near the eighth main surface 10db of the fourth resin layer 10d is increased, and this, combined with the shortened distance between the second resin material 11b in the second resin layer 10b and the second resin material 11b in the fourth resin layer 10d, results in excellent adhesion between the second resin layer 10b and the fourth resin layer 10d. Furthermore, similar to the mechanism described above, during the hot press processing, the first resin material 11a, which is resistant to dimensional change, suppresses dimensional change in the second resin material 11b at the eighth main surface 10db of the fourth resin layer 10d, thereby suppressing warpage due to dimensional change in the fourth resin layer 10d. Note that the eighth main surface 10db of the fourth resin layer 10d, or in this case the interface between the second resin layer 10b and the fourth resin layer 10d, can be easily confirmed using a fluorescence microscope in addition to a scanning electron microscope.

[0125] In the example shown in Figure 11, when looking at the second cross section as an example of a cross section along the thickness direction, the presence ratio of the second resin material 11b on the eighth main surface 10db of the fourth resin layer 10d is shown to be 40% or more and 70% or less. However, when looking at the first cross section perpendicular to the second cross section as an example of a cross section along the thickness direction, the presence ratio of the second resin material 11b on the eighth main surface 10db of the fourth resin layer 10d may also be 40% or more and 70% or less.

[0126] In the laminated substrate 2, when viewed in a cross section along the thickness direction, the abundance ratio of the second resin material 11b on the third main surface 10ba of the second resin layer 10b is preferably 40% or more and 70% or less. In this case, when manufacturing the laminated structure of the second resin layer 10b and the fourth resin layer 10d by hot pressing, similar to the mechanism described above, the fluidity of the second resin material 11b present in the vicinity of the third main surface 10ba of the second resin layer 10b is increased, and this, combined with the shortened distance between the second resin material 11b in the second resin layer 10b and the second resin material 11b in the fourth resin layer 10d, results in excellent adhesion between the second resin layer 10b and the fourth resin layer 10d. Furthermore, similar to the mechanism described above, during the hot press processing, the dimensional change of the second resin material 11b is suppressed by the first resin material 11a, which is resistant to dimensional change, on the third main surface 10ba of the second resin layer 10b, thereby suppressing warpage due to dimensional change of the second resin layer 10b. Note that the third main surface 10ba of the second resin layer 10b, in this case the interface between the second resin layer 10b and the fourth resin layer 10d, can be easily confirmed using a fluorescence microscope in addition to a scanning electron microscope.

[0127] In the example shown in Figure 11, when looking at the second cross section as an example of a cross section along the thickness direction, the presence ratio of the second resin material 11b on the third main surface 10ba of the second resin layer 10b is shown to be 40% or more and 70% or less. However, when looking at the first cross section perpendicular to the second cross section as an example of a cross section along the thickness direction, the presence ratio of the second resin material 11b on the third main surface 10ba of the second resin layer 10b may also be 40% or more and 70% or less.

[0128] The thicknesses of the first resin layer 10a, the second resin layer 10b, the third resin layer 10c, and the fourth resin layer 10d may be the same as one another, may be different from one another, or may be partially different from one another.

[0129] The second conductor layer 20b is in contact with the sixth main surface 10cb of the third resin layer 10c. As described above, no other layer, such as an adhesive layer, is provided between the third resin layer 10c and the second conductor layer 20b.

[0130] The second conductor layer 20b may be a surface extending over the entire sixth main surface 10cb of the third resin layer 10c, or may be a patterned shape patterned into wiring or the like on a portion of the sixth main surface 10cb of the third resin layer 10c.

[0131] The third conductor layer 20c is in contact with the seventh main surface 10da of the fourth resin layer 10d. As such, no other layer, such as an adhesive layer, is provided between the fourth resin layer 10d and the third conductor layer 20c.

[0132] The third conductor layer 20c may be a surface extending over the entire seventh main surface 10da of the fourth resin layer 10d, or may be a patterned shape patterned into wiring or the like on a portion of the seventh main surface 10da of the fourth resin layer 10d.

[0133] The constituent materials of the first conductor layer 20a, the second conductor layer 20b, and the third conductor layer 20c may be the same as or different from one another, or may be partially different from one another.

[0134] The thicknesses of the first conductor layer 20a, the second conductor layer 20b, and the third conductor layer 20c may be the same as one another, may be different from one another, or may be partially different from one another.

[0135] The laminate substrate 2 forms a stripline-type transmission line. Specifically, the laminate substrate 2 has a first conductor layer 20a as a signal line and a second conductor layer 20b and a third conductor layer 20c as ground electrodes. In this configuration, the second conductor layer 20b and the third conductor layer 20c may be electrically connected via an interlayer connection conductor (not shown) that penetrates the first resin layer 10a, the second resin layer 10b, the third resin layer 10c, and the fourth resin layer 10d in the thickness direction. Note that the second conductor layer 20b and the third conductor layer 20c do not have to be electrically connected.

[0136] The laminate substrate 2 is manufactured, for example, by carrying out the following steps after manufacturing the laminate substrate 1. First, after manufacturing the laminate substrate 1, a conductor-layered resin sheet having a second conductor layer 20b adjacent to one main surface (later to become the sixth main surface 10cb) of a resin sheet (later to become the third resin layer 10c) is laminated from the other main surface (later to become the fifth main surface 10ca) to the second main surface 10ab of the first resin layer 10a. Furthermore, a conductor-layered resin sheet having a third conductor layer 20c adjacent to one main surface (later to become the seventh main surface 10da) of a resin sheet (later to become the fourth resin layer 10d) is laminated from the other main surface (later to become the eighth main surface 10db) to the third main surface 10ba of the second resin layer 10b. The resulting laminate is then heated and pressed in the thickness direction, thereby performing hot-press processing.

[0137] The temperature during the hot press processing is preferably equal to or higher than the melting point of the second resin material 11b and equal to or lower than the melting point of the first resin material 11a (i.e., equal to or higher than Tm2 and equal to or lower than Tm1), and more preferably equal to or higher than the melting point of the second resin material 11b and equal to or lower than a temperature 10°C lower than the melting point of the first resin material 11a (i.e., equal to or higher than Tm2 and equal to or lower than (Tm1-10)). In this case, the temperature rise rate during the hot press processing is preferably equal to or higher than 5°C / min, and more preferably equal to or higher than 5°C / min and equal to or lower than 50°C / min. When the hot press processing is performed under the above temperature conditions, for example, as shown in FIG. 11, the second resin material 11b can be present at a concentration of 40% or higher and 70% or lower on the third main surface 10ba of the second resin layer 10b, the fifth main surface 10ca of the third resin layer 10c, and the eighth main surface 10db of the fourth resin layer 10d while maintaining a flat shape along the surface direction.

[0138] Third Embodiment A laminated substrate according to a third embodiment of the present invention constitutes a microstrip transmission line.

[0139] FIG. 12 is a cross-sectional view schematically illustrating an example of a laminated substrate according to the third embodiment of the present invention, as viewed from the second cross section.

[0140] The laminated substrate 3 shown in FIG. 12 includes a first resin layer 10a, a second resin layer 10b, a first conductor layer 20a, and a conductor layer 20x.

[0141] The multilayer substrate 3 has the same configuration as the multilayer substrate 1, except that the multilayer substrate 3 is provided with a conductor layer 20x.

[0142] The conductor layer 20x is in contact with the second main surface 10ab of the first resin layer 10a. As described above, no other layer such as an adhesive layer is provided between the first resin layer 10a and the conductor layer 20x.

[0143] The constituent materials of the first conductor layer 20a and the conductor layer 20x may be the same as or different from each other.

[0144] The thickness of the first conductor layer 20a and the thickness of the conductor layer 20x may be the same as or different from each other.

[0145] The laminated substrate 3 forms a microstrip transmission line. Specifically, the laminated substrate 3 has a first conductor layer 20a as a signal line and a conductor layer 20x as a ground electrode.

[0146] The laminated substrate 3 is manufactured in the same manner as the laminated substrate 1, except that the conductor layer 20x is not removed.

[0147] Fourth Embodiment A laminated substrate according to a fourth embodiment of the present invention constitutes a coplanar transmission line.

[0148] FIG. 13 is a cross-sectional view schematically illustrating an example of a laminated substrate according to a fourth embodiment of the present invention, as viewed from the second cross section.

[0149] The laminated substrate 4 shown in FIG. 13 includes a first resin layer 10a, a second resin layer 10b, a first conductor layer 20a, a conductor layer 20y, and a conductor layer 20z.

[0150] The multilayer substrate 4 has the same configuration as the multilayer substrate 1, except that the multilayer substrate 4 is provided with the conductor layer 20y and the conductor layer 20z.

[0151] The conductor layer 20y is located between the first resin layer 10a and the second resin layer 10b and is provided so as to be in contact with the first main surface 10aa of the first resin layer 10a and the fourth main surface 10bb of the second resin layer 10b. As such, no other layer, such as an adhesive layer, is provided between the first resin layer 10a and the conductor layer 20y, or between the second resin layer 10b and the conductor layer 20y.

[0152] The conductor layer 20y is preferably provided across the interface between the first resin layer 10a and the second resin layer 10b, so that the interface between the first resin layer 10a and the conductor layer 20y and the interface between the second resin layer 10b and the conductor layer 20y are shifted in the thickness direction from the interface between the first resin layer 10a and the second resin layer 10b, thereby suppressing peeling at the interface between the first resin layer 10a and the conductor layer 20y and the interface between the second resin layer 10b and the conductor layer 20y.

[0153] The conductor layer 20z is located between the first resin layer 10a and the second resin layer 10b and is provided so as to be in contact with the first main surface 10aa of the first resin layer 10a and the fourth main surface 10bb of the second resin layer 10b. As such, no other layer, such as an adhesive layer, is provided between the first resin layer 10a and the conductor layer 20z, or between the second resin layer 10b and the conductor layer 20z.

[0154] The conductor layer 20z is preferably provided across the interface between the first resin layer 10a and the second resin layer 10b, so that the interface between the first resin layer 10a and the conductor layer 20z and the interface between the second resin layer 10b and the conductor layer 20z are shifted in the thickness direction from the interface between the first resin layer 10a and the second resin layer 10b, thereby suppressing peeling at the interface between the first resin layer 10a and the conductor layer 20z and the interface between the second resin layer 10b and the conductor layer 20z.

[0155] The constituent materials of the first conductor layer 20a, the conductor layer 20y, and the conductor layer 20z may be the same as or different from one another, or may be partially different from one another.

[0156] The thicknesses of the first conductor layer 20a, the conductor layer 20y, and the conductor layer 20z may be the same as each other, may be different from each other, or may be partially different.

[0157] The laminated substrate 4 forms a coplanar transmission line. Specifically, the laminated substrate 4 has a first conductor layer 20a as a signal line and conductor layers 20y and 20z as ground electrodes. In this configuration, the conductor layers 20y and 20z may be integrated by being connected in the planar direction.

[0158] The laminated substrate 4 is manufactured in the same manner as the laminated substrate 1, except that, for example, when producing the second resin sheet 210b with a conductor layer (see Figure 5), in addition to the first conductor layer 20a, conductor layer 20y and conductor layer 20z are arranged adjacent to the fourth main surface 110bb side of the second resin sheet 110b.

[0159] Fifth Embodiment A laminated substrate according to a fifth embodiment of the present invention has a bent portion.

[0160] FIG. 14 is a cross-sectional view schematically illustrating a state in which an example of a laminated substrate according to a fifth embodiment of the present invention is viewed from a first cross section.

[0161] The laminated substrate 5 shown in FIG. 14 includes a first resin layer 10a, a second resin layer 10b, a fourth resin layer 10d, a first conductor layer 20a, a third conductor layer 20c, and a conductor layer 20x.

[0162] The laminated substrate 5 has the same configuration as the laminated substrate 2, except that a conductor layer 20x is provided instead of the third resin layer 10c and the second conductor layer 20b.

[0163] The conductor layer 20x is in contact with the second main surface 10ab of the first resin layer 10a. As described above, no other layer such as an adhesive layer is provided between the first resin layer 10a and the conductor layer 20x.

[0164] The constituent materials of the first conductor layer 20a, the third conductor layer 20c, and the conductor layer 20x may be the same as or different from one another, or may be partially different from one another.

[0165] The thicknesses of the first conductor layer 20a, the third conductor layer 20c, and the conductor layer 20x may be the same as each other, may be different from each other, or may be partially different from each other.

[0166] The laminated substrate 5 has a bent portion 30. In the example shown in Fig. 14, the laminated substrate 5 has two bent portions 30. Note that the laminated substrate 5 may have one bent portion 30, or three or more bent portions 30.

[0167] The position of the bent portion 30 is not particularly limited.

[0168] Since the laminated substrate 5 has the bent portion 30, even if tensile stress is applied to the laminated substrate 5 by pulling the laminated substrate 5, the number of locations where the tensile stress is concentrated is reduced, making the laminated substrate 5 less likely to break. Furthermore, even if bending stress is applied to the laminated substrate 5 by bending the laminated substrate 5, the number of locations where the bending stress is concentrated is reduced, making the laminated substrate 5 less likely to break. As a result, the laminated substrate 5 has excellent tensile resistance and bending resistance.

[0169] Furthermore, since the laminated substrate 5 has the bent portion 30, when it is used as a circuit board, it is possible to configure a transmission line in a bent state.

[0170] Sixth Embodiment A laminated substrate according to a sixth embodiment of the present invention has a recessed portion in addition to a bent portion.

[0171] FIG. 15 is a cross-sectional view schematically illustrating a state in which an example of a laminated substrate according to a sixth embodiment of the present invention is viewed from a first cross section.

[0172] The laminated substrate 6 shown in Figure 15 has a first resin layer 10a, a second resin layer 10b, a third resin layer 10c, a fourth resin layer 10d, a fifth resin layer 10e, a first conductor layer 20a, a second conductor layer 20b, a third conductor layer 20c, a fourth conductor layer 20d, and a conductor layer 20x.

[0173] The laminated substrate 6 has the same configuration as the laminated substrate 5, except that it is provided with a third resin layer 10c, a fifth resin layer 10e, a second conductor layer 20b, and a fourth conductor layer 20d.

[0174] A fifth major surface 10ca of the third resin layer 10c faces the second major surface 10ab of the first resin layer 10a, with the conductor layer 20x sandwiched therebetween.

[0175] The fifth resin layer 10e has a ninth main surface 10ea and a tenth main surface 10eb that face each other in the thickness direction.

[0176] The ninth main surface 10ea of ​​the fifth resin layer 10e faces the sixth main surface 10cb of the third resin layer 10c, with the second conductor layer 20b sandwiched therebetween.

[0177] The fifth resin layer 10e preferably contains the first resin material 11a and the second resin material 11b. Furthermore, in the laminate substrate 6, when viewed in the first cross section, the abundance ratio of the second resin material 11b at the interface between the fifth resin layer 10e and the second conductor layer 20b is preferably 40% or more and 70% or less. In this case, similar to the mechanism described above, the adhesion between the fifth resin layer 10e and the second conductor layer 20b is excellent, and further, warpage caused by differences in dimensional changes between the fifth resin layer 10e and the second conductor layer 20b is suppressed.

[0178] The thicknesses of the first resin layer 10a, the second resin layer 10b, the third resin layer 10c, the fourth resin layer 10d, and the fifth resin layer 10e may be the same as each other, may be different from each other, or may be partially different from each other.

[0179] The second conductor layer 20b is located between the third resin layer 10c and the fifth resin layer 10e, and is provided so as to be in contact with the sixth main surface 10cb of the third resin layer 10c and the ninth main surface 10ea of ​​the fifth resin layer 10e.

[0180] The fourth conductor layer 20d is in contact with the tenth main surface 10eb of the fifth resin layer 10e. As described above, no other layer such as an adhesive layer is provided between the fifth resin layer 10e and the fourth conductor layer 20d.

[0181] The constituent materials of the first conductor layer 20a, the second conductor layer 20b, the third conductor layer 20c, the fourth conductor layer 20d, and the conductor layer 20x may be the same as each other, may be different from each other, or may be partially different from each other.

[0182] The thicknesses of the first conductor layer 20a, the second conductor layer 20b, the third conductor layer 20c, the fourth conductor layer 20d, and the conductor layer 20x may be the same as each other, may be different from each other, or may be partially different.

[0183] The laminated substrate 6 has bent portions 30. In the example shown in FIG.

[0184] The presence of the bent portion 30 in the laminated substrate 6 gives it excellent tensile resistance and bending resistance, similar to the laminated substrate 5 .

[0185] Furthermore, since the laminated substrate 6 has the bent portion 30, when it is used as a circuit board, it is possible to configure a transmission line in a bent state.

[0186] The laminated substrate 6 has a recess 40 in addition to the bent portion 30. In the example shown in Fig. 15, the recess 40 is provided so as to penetrate through the fourth conductor layer 20d, the fifth resin layer 10e, the second conductor layer 20b, and the third resin layer 10c in the thickness direction and reach the conductor layer 20x.

[0187] The position of the recess 40 is not particularly limited.

[0188] The size (width, height, etc.) of the recess 40 is not particularly limited.

[0189] The recess 40 can be used as a space when mounting electronic components, etc. on the laminated substrate 6. When the electronic components, etc. are mounted on the laminated substrate 6 in the recess 40, it is possible to reduce the overall thickness after the electronic components, etc. are mounted on the laminated substrate 6.

[0190] The laminated substrate of the present invention is not limited to the above-described embodiment, and various applications and modifications can be made within the scope of the present invention with respect to the configuration of the laminated substrate, manufacturing conditions, and the like.

[0191] In the laminated substrate of the present invention, the number of resin layers is not particularly limited as long as it is two or more layers including the first resin layer and the second resin layer.

[0192] In the laminated substrate of the present invention, the number of conductor layers is not particularly limited as long as it is one or more layers including the first conductor layer.

[0193] EXAMPLES Hereinafter, examples will be given that more specifically disclose the laminated substrate of the present invention, but the present invention is not limited to the following examples.

[0194] Examples 1 to 10 The laminated substrates of Examples 1 to 10 were manufactured by the laminated substrate manufacturing method of Embodiment 1. The manufacturing conditions were as shown in Table 1.

[0195] [Comparative Example 1] A laminated substrate of Comparative Example 1 was produced by the same production method as in Examples 1 to 10, except that the hot press processes in the <step of producing a resin sheet with a conductor layer> and the <step of laminating resin sheets with a conductor layer> were carried out at a temperature outside the range of not less than Tm2 and not more than Tm1, specifically at a temperature higher than Tm1. Other production conditions were as shown in Table 1.

[0196] [Comparative Example 2] A laminated substrate of Comparative Example 2 was manufactured using the same manufacturing method as in Examples 1 to 10, but using a first resin material and a second resin material having a relationship of Tm1<Tm2. Other manufacturing conditions were as shown in Table 1.

[0197] The "adhesive PFA" shown in Table 1 is "Fluon+ (registered trademark) EA-2000" manufactured by AGC.

[0198] The "amount" of the second resin material shown in Table 1 is the amount of the second resin material mixed relative to the first resin material when preparing the resin composition in the <step of producing a resin sheet with a conductor layer>.

[0199] The conditions for "hot press processing" shown in Table 1 are common to the <step of producing a resin sheet with a conductor layer> and the <step of laminating resin sheets with a conductor layer>.

[0200] [Evaluation] The following evaluations were carried out on the laminated substrates of Examples 1 to 10 and Comparative Examples 1 and 2. The evaluation results are shown in Table 1.

[0201] <Abundance ratio of second resin material> The abundance ratio of the second resin material in the first main surface of the first resin layer (referred to as "abundance ratio of second resin material" in Table 1) was determined by the method described above (see FIG. 3).

[0202] <Thermal Expansion Coefficient in the Planar Direction of the First Resin Layer> First, the first conductor layer and the second resin layer were removed from the laminate substrate by peeling, etching, or other methods, to extract the first resin layer. Next, a sample measuring 20 mm in length and 4 mm in width was cut out from the first resin layer and placed on the probe of a Seiko Instruments Inc. thermomechanical analyzer with a chuck distance of 10 mm. Then, while applying a 5 g load, the sample was heated to 170°C at a heating rate of 40°C / min and then cooled to 30°C at a cooling rate of 10°C / min. The change in the chuck distance during the cooling process was measured in the temperature range from 100°C to 50°C, thereby determining the thermal expansion coefficient of the first resin layer in the planar direction (referred to as "Thermal Expansion Coefficient of the First Resin Layer" in Table 1).

[0203] <Peel Strength> As an index of adhesion between the first resin layer and the first conductor layer, the peel strength between the first resin layer and the first conductor layer (when peeled off in a 90° direction) was measured in accordance with 5.7 of "JIS C 6481-1996" except that the first conductor layer was peeled off from the first resin layer.

[0204] <Warpage Amount> The warpage amount of the laminated substrate was measured in accordance with 5.22 of JIS C 6481-1996, with the size of the sample being 120 mm long x 120 mm wide.

[0205]

[0206] As shown in Table 1, in the laminate substrates of Examples 1 to 10, which satisfied all of the following conditions: Tm1 > Tm2, ​​|CTE3 - CTE2| > |CTE3 - CTE1|, and the proportion of the second resin material at the interface between the first resin layer and the first conductor layer was 40% or more and 70% or less, the peel strength between the first resin layer and the first conductor layer was high, and therefore the adhesion between them was excellent. Furthermore, in the laminate substrates of Examples 1 to 10, the thermal expansion coefficient in the plane direction of the first resin layer was close to the thermal expansion coefficient (CTE3) in the plane direction of the first conductor layer, and therefore warpage due to differences in dimensional changes between the first resin layer and the first conductor layer was suppressed.

[0207] Among the laminated substrates of Examples 1 to 10, the laminated substrates of Examples 2 to 10, in which the proportion of the second resin material at the interface between the first resin layer and the first conductor layer was 50% or more and 70% or less, had superior adhesion between the first resin layer and the first conductor layer compared to the laminated substrate of Example 1, in which the proportion of the second resin material at the interface between the first resin layer and the first conductor layer was 40%.

[0208] Of the laminated substrates of Examples 1 to 10, in the laminated substrates of Examples 1 to 3 and 5 to 10 in which the proportion of the second resin material at the interface between the first resin layer and the first conductor layer was 40% or more and 60% or less, warping was suppressed compared to the laminated substrate of Example 4 in which the proportion of the second resin material at the interface between the first resin layer and the first conductor layer was 70%.

[0209] In the laminated substrate of Comparative Example 1, in which the proportion of the second resin material at the interface between the first resin layer and the first conductor layer was greater than 70%, warping was not suppressed compared to the laminated substrates of Examples 1 to 10.

[0210] In the laminated substrate of Comparative Example 2, which used a first resin material and a second resin material in which Tm1 < Tm2, ​​the adhesion between the first resin layer and the first conductor layer was inferior compared to the laminated substrates of Examples 1 to 10.

[0211] The present specification discloses the following:

[0212] <1> A first resin layer having a first main surface and a second main surface opposed to each other in a thickness direction; a second resin layer having a third main surface and a fourth main surface opposed to each other in the thickness direction, the fourth main surface being disposed so as to face the first main surface; and a first conductor layer located between the first resin layer and the second resin layer and disposed so as to be in contact with the first main surface and the fourth main surface, wherein the first resin layer and the second resin layer each contain a first resin material made of a thermoplastic resin and a second resin material made of a thermoplastic resin and dispersed in the first resin material, wherein Tm1 is a melting point of the first resin material and Tm2 is a melting point of the second resin material, and Tm1>Tm2 is satisfied; a first cross section taken along the thickness direction, wherein the thermal expansion coefficient of the first resin material is CTE1, the thermal expansion coefficient of the second resin material is CTE2, and the thermal expansion coefficient of the first conductor layer is CTE3, and |CTE3-CTE2|>|CTE3-CTE1| holds; and when viewing a first cross section taken along the thickness direction, the presence ratio of the second resin material at the interface between the first resin layer and the first conductor layer is 40% or more and 70% or less.

[0213] <2> The laminated substrate according to <1>, wherein, when viewed from the first cross section, the average thickness of the second resin material at the interface between the first resin layer and the first conductor layer is 5 μm or less.

[0214] <3> The laminated substrate according to <1> or <2>, wherein the second resin material has an average aspect ratio of 3 or more when viewed from the first cross section.

[0215] <4> The laminated substrate according to any one of <1> to <3>, wherein, when the first cross section is viewed, an average inclination of the second resin material with respect to the surface direction is 15° or less.

[0216] <5> The laminated substrate according to any one of <1> to <4>, wherein, when viewed in a second cross section perpendicular to the first cross section along the thickness direction, the second resin material is in contact with a part of a main surface of the first conductor layer facing the first resin layer.

[0217] <6> The laminated substrate according to any one of <1> to <5>, which has the first conductor layer as a signal line for transmitting a signal, and forms a transmission line.

[0218] <7> The laminated substrate according to any one of <1> to <6>, further comprising a third resin layer having a fifth main surface and a sixth main surface opposed to each other in the thickness direction, the fifth main surface being provided so as to face the second main surface.

[0219] <8> The laminated substrate according to <7>, wherein the third resin layer includes the first resin material and the second resin material, and when viewed in a cross section along the thickness direction, a presence ratio of the second resin material in the fifth main surface is 40% or more and 70% or less.

[0220] <9> The laminated substrate according to <7> or <8>, further comprising a second conductor layer in contact with the sixth main surface.

[0221] <10> The laminated substrate according to any one of <7> to <9>, further comprising a fourth resin layer having a seventh main surface and an eighth main surface opposed to each other in the thickness direction, the eighth main surface being provided so as to face the third main surface.

[0222] <11> The laminated substrate according to <10>, wherein the fourth resin layer includes the first resin material and the second resin material, and when viewed in a cross section along the thickness direction, a presence ratio of the second resin material in the eighth main surface is 40% or more and 70% or less.

[0223] <12> The laminated substrate according to <10> or <11>, further comprising a third conductor layer in contact with the seventh main surface.

[0224] <13> The laminated substrate according to any one of <1> to <12>, wherein CTE1<CTE2.

[0225] <14> The laminated substrate according to any one of <1> to <13>, wherein CTE1<CTE3.

[0226] <15> The laminated substrate according to any one of <1> to <14>, wherein CTE2>>CTE3.

[0227] <16> The laminated substrate according to any one of <1> to <15>, wherein, when the relative dielectric constant of the first resin material is Dk1 and the relative dielectric constant of the second resin material is Dk2, Dk1>Dk2.

[0228] <17> The laminated substrate according to any one of <1> to <16>, wherein, when the dielectric loss tangent of the first resin material is Df1 and the dielectric loss tangent of the second resin material is Df2, Df1>Df2.

[0229] <18> The laminated substrate according to any one of <1> to <17>, wherein the first resin material is made of a liquid crystal polymer.

[0230] <19> The laminated substrate according to any one of <1> to <18>, wherein the second resin material is made of perfluoroalkoxyalkane, thermoplastic polyimide, polyphenylene sulfide, polyether ether ketone, polyphenylene ether, polymethylpentene, cross-linked polyethylene, or polynorbornene.

[0231] <20> The laminated substrate according to <19>, wherein the second resin material is made of perfluoroalkoxyalkane, polymethylpentene, or polynorbornene.

[0232] 1, 2, 3, 4, 5, 6 Laminated substrate 10a First resin layer 10aa, 110aa First main surface 10ab, 110ab Second main surface 10b Second resin layer 10ba, 110ba Third main surface 10bb, 110bb Fourth main surface 10c Third resin layer 10ca Fifth main surface 10cb Sixth main surface 10d Fourth resin layer 10da Seventh main surface 10db Eighth main surface 10e Fifth resin layer 10ea Ninth main surface 10eb Tenth main surface 11a First resin material 11b Second resin material 20a First conductor layer 20b Second conductor layer 20c Third conductor layer 20d Fourth conductor layer 20x, 20y, 20z Conductor layer 30 Bent portion 40 Recess 110a First resin sheet 110b Second resin sheet 210a First resin sheet with conductor layer 210b Second resin sheet with conductor layer K Dimension in thickness direction of imaging range L Dimension in surface direction of imaging range L1, L2, L3, L4, L5, L6 Dimension in surface direction of portion of second resin material that contacts interface between first resin layer and first conductor layer P Rectangle P1 Short side P2 Long side Q Ellipse Q1 Minor axis Q2 Major axis θ Angle

Claims

1. A first resin layer having a first main surface and a second main surface facing each other in the thickness direction, A second resin layer having a third main surface and a fourth main surface facing each other in the thickness direction, wherein the fourth main surface is provided facing the first main surface, The material comprises a first conductor layer located between the first resin layer and the second resin layer, and provided in contact with the first main surface and the fourth main surface, The first resin layer and the second resin layer each comprise a first resin material made of a thermoplastic resin and a second resin material made of a thermoplastic resin and dispersed in the first resin material. If the melting point of the first resin material is Tm1 and the melting point of the second resin material is Tm2, ​​then Tm1 > Tm2. In the planar direction perpendicular to the thickness direction, if the thermal expansion coefficient of the first resin material is CTE1, the thermal expansion coefficient of the second resin material is CTE2, and the thermal expansion coefficient of the first conductor layer is CTE3, then |CTE3 - CTE2| > |CTE3 - CTE1|. A laminated substrate characterized in that, when viewed in a first cross-section along the thickness direction, the proportion of the second resin material at the interface between the first resin layer and the first conductor layer is 40% or more and 70% or less.

2. The laminated substrate according to claim 1, wherein, when viewed in the first cross-section, the average thickness of the second resin material at the interface between the first resin layer and the first conductor layer is 5 μm or less.

3. The laminated substrate according to claim 1 or 2, wherein, when viewed in the first cross-section, the average aspect ratio of the second resin material is 3 or more.

4. The laminated substrate according to claim 1 or 2, wherein, when the first cross-section is viewed, the average inclination of the second resin material with respect to the surface direction is 15° or less.

5. The laminated substrate according to claim 1 or 2, wherein when a second cross-section perpendicular to the first cross-section is viewed along the thickness direction, the second resin material is in contact with a part of the main surface of the first conductor layer on the first resin layer side.

6. The laminated substrate according to claim 1 or 2, having the first conductor layer as a signal line for transmitting signals, thereby forming a transmission line.

7. The laminated substrate according to claim 1 or 2, further comprising a third resin layer having a fifth main surface and a sixth main surface opposite to each other in the thickness direction, wherein the fifth main surface is provided so as to face the second main surface.

8. The third resin layer comprises the first resin material and the second resin material, The laminated substrate according to claim 7, wherein, when viewed in cross-section along the thickness direction, the proportion of the second resin material in the fifth main surface is 40% or more and 70% or less.

9. The laminated substrate according to claim 7, further comprising a second conductive layer in contact with the sixth main surface.

10. The laminated substrate according to claim 7, further comprising a fourth resin layer having a seventh main surface and an eighth main surface opposite to each other in the thickness direction, wherein the eighth main surface is provided facing the third main surface.

11. The fourth resin layer comprises the first resin material and the second resin material, The laminated substrate according to claim 10, wherein, when viewed in cross-section along the thickness direction, the proportion of the second resin material in the eighth main surface is 40% or more and 70% or less.

12. The laminated substrate according to claim 10, further comprising a third conductive layer in contact with the seventh main surface.

13. The laminated substrate according to claim 1 or 2, wherein CTE1 < CTE2.

14. The laminated substrate according to claim 1 or 2, wherein CTE1 < CTE3.

15. The laminated substrate according to claim 1 or 2, wherein CTE2 > CTE3.

16. The laminated substrate according to claim 1 or 2, wherein the relative permittivity of the first resin material is Dk1 and the relative permittivity of the second resin material is Dk2, and Dk1 > Dk2.

17. The laminated substrate according to claim 1 or 2, wherein Df1 is the dielectric loss tangent of the first resin material and Df2 is the dielectric loss tangent of the second resin material, and Df1 > Df2.

18. The laminated substrate according to claim 1 or 2, wherein the first resin material is made of a liquid crystal polymer.

19. The laminated substrate according to claim 1 or 2, wherein the second resin material consists of a perfluoroalkoxyalkane, a thermoplastic polyimide, a polyphenylene sulfide, a polyetheretherketone, a polyphenylene ether, a polymethylpentene, a crosslinked polyethylene, or a polynorbornene.

20. The laminated substrate according to claim 19, wherein the second resin material comprises a perfluoroalkoxyalkane, polymethylpentene, or polynorbornene.