Resin sheet body, resin sheet body with conductor layer, and multilayer circuit board

Abstract

The present invention provides a resin sheet body which is capable of exhibiting sufficient adhesive strength (peel strength) even when a metal layer having a low surface roughness is disposed, and which is capable of reducing transmission loss.　A resin sheet body (10) according to the present invention has a first main surface (11) and a second main surface (12) opposite to the first main surface (11), and contains a wholly aromatic polyester. This resin sheet body (10) is characterized in that: the wholly aromatic polyester contains, in the main chain, a first constituent unit that has a naphthalene ring and a second constituent unit that has a benzene ring, and the number of moles of the first constituent unit is greater than the number of moles of the second constituent unit; if the scattering spectrum of a portion of the resin sheet body inwardly extending from the first main surface to a depth of 5 µm is determined using a grazing incidence X-ray scattering method, the angle indicating the maximum value of the main peak is present in a region from 2θ = 18.0 degrees to 2θ = 19.0 degrees and the angle indicating the maximum value of a sub-peak is present in a region from 2θ = 26.0 degrees to 2θ = 27.0 degrees; and if the scattering spectrum of a portion of the resin sheet body further inwardly extending to a depth of 5 µm or more from the first main surface is determined using a grazing incidence X-ray scattering method, the angle indicating the maximum value of the main peak is present in a region from 2θ = 19.1 degrees to 2θ = 20.0 degrees and the angle indicating the maximum value of a sub-peak is present in a region from 2θ = 27.1 degrees to 2θ = 28.0 degrees.

Description

Resin sheet body, resin sheet body with conductor layer, and multilayer circuit board

[0001] The present invention relates to a resin sheet, a resin sheet with a conductor layer, and a multilayer circuit board.

[0002] A resin sheet body with a conductor layer, in which a conductor layer is disposed on the surface of a resin sheet body, has been conventionally used as a material for manufacturing circuit boards such as flexible wiring boards and circuit boards for semiconductor packaging. Thermoplastic liquid crystal polymers are known to be used as a resin constituting the resin sheet body because of their low moisture absorption, heat resistance, chemical resistance, and excellent electrical properties.

[0003] Patent Document 1 discloses a metal-clad laminate as a resin sheet body with a conductor layer using a thermoplastic liquid crystal polymer, in which a metal foil is bonded to at least one surface of a thermoplastic liquid crystal polymer film, in which the surface roughness of the metal foil is less than 2.0 μm and the thickness of the skin layer of the thermoplastic liquid crystal polymer film is equal to or less than the surface roughness of the metal foil.

[0004] Patent No. 6656231

[0005] In the metal-clad laminate (resin sheet with a conductor layer) described in Patent Document 1, a method of increasing the surface roughness of the surface of the metal foil that is bonded to the thermoplastic liquid crystal polymer film can be considered as a means for improving the adhesive strength (peel strength) between the thermoplastic liquid crystal polymer film and the metal foil. However, increasing the surface roughness of the metal foil surface causes the problem of increased transmission loss. In other words, there is a trade-off between improving adhesive strength (peel strength) and reducing transmission loss. The metal-clad laminate (resin sheet with a conductor layer) described in Patent Document 1 was unable to sufficiently achieve both improved adhesive strength (peel strength) and reduced transmission loss, leaving room for improvement.

[0006] The present invention has been made to solve the above problems, and the object of the present invention is to provide a resin sheet body that exhibits sufficient adhesive strength (peel strength) even when a metal layer with low surface roughness is placed thereon, and that can reduce transmission loss.

[0007] The resin sheet of the present invention has a first main surface and a second main surface opposite to the first main surface, and contains a wholly aromatic polyester, wherein the wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in a main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit, and when a scattering spectrum of the resin sheet is measured using a grazing incidence X-ray scattering method, the resin sheet ... resin sheet contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in a main chain, and the resin sheet contains a second structural unit having a naphthalene ring and a second structural unit having a benzene ring in a main chain. A scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 26.0 degrees to 27.0 degrees, and in at least a portion of the resin sheet body that is 5 μm or more away inward from the first main surface, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees.

[0008] Another aspect of the present invention provides a resin sheet having a first main surface and a second main surface opposite the first main surface, the resin sheet comprising a wholly aromatic polyester, wherein the wholly aromatic polyester comprises a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in a main chain, the number of moles of the first structural unit being greater than the number of moles of the second structural unit, and wherein when a scattering spectrum is measured using a grazing incidence X-ray scattering method with an incident angle (ω) of 0.18 degrees with respect to the first main surface of the resin sheet, the angle at which the maximum value of the main peak is The scattering spectrum obtained is characterized in that the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the subpeak is in the range of 2θ = 26.0 degrees to 27.0 degrees, and when the scattering spectrum is measured using an oblique incidence X-ray scattering method with an incident angle (ω) of 0.30 degrees with respect to the first main surface of the resin sheet, the scattering spectrum obtained is that the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the subpeak is in the range of 2θ = 27.1 degrees to 28.0 degrees.

[0009] The resin sheet body with a conductor layer of the present invention is characterized by comprising the resin sheet body of the present invention described above and a conductor layer disposed on a first main surface of the resin sheet body.

[0010] The multilayer circuit board of the present invention has a first main surface and a second main surface opposite to the first main surface, and comprises a resin sheet body with a conductor layer including a resin sheet body containing a wholly aromatic polyester and a conductor layer disposed on the first main surface, wherein the wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit, and when a scattering spectrum of the resin sheet body is measured using a grazing incidence X-ray scattering method, a scattering spectrum of the resin sheet body is measured within 5 μm inward from the first main surface of the resin sheet body. and a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees in at least a portion of the range 5 μm or more away from the first main surface of the resin sheet body inward, such that the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees.

[0011] Another aspect of the present invention provides a multilayer circuit board having a first main surface and a second main surface opposite the first main surface, the multilayer circuit board comprising a resin sheet body with a conductor layer including a resin sheet body containing a wholly aromatic polyester and a conductor layer disposed on the first main surface, the wholly aromatic polyester including a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in a main chain, the number of moles of the first structural unit being greater than the number of moles of the second structural unit, and when a scattering spectrum is measured using a grazing incidence X-ray scattering method with an incident angle (ω) of 0.18 degrees with respect to the first main surface of the resin sheet body, A scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 26.0 degrees to 27.0 degrees, and when the scattering spectrum is measured using oblique incidence X-ray scattering at an incident angle (ω) of 0.30 degrees with respect to the first main surface of the resin sheet body, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees.

[0012] According to the present invention, it is possible to provide a resin sheet body that exhibits sufficient adhesive strength (peel strength) even when a metal layer with low surface roughness is disposed thereon, and that can reduce transmission loss.

[0013] FIG. 1 is a cross-sectional view schematically showing an example of a resin sheet body according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of a resin sheet body with a conductor layer according to a second embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing an example of a multilayer circuit board according to a third embodiment of the present invention. FIG. 4 is a cross-sectional view schematically showing another example of a multilayer circuit board according to the third embodiment of the present invention. FIG. 5 is a cross-sectional view schematically showing another example of a multilayer circuit board according to the third embodiment of the present invention. FIG. 6 is a cross-sectional view schematically showing another example of a multilayer circuit board according to the third embodiment of the present invention. FIG. 7 is a cross-sectional view schematically showing another example of a multilayer circuit board according to the third embodiment of the present invention. FIG. 8A is a chart of a scattering spectrum measured by oblique incidence X-ray scattering (incident angle (ω) = 0.18 degrees) using the resin sheet body with a conductor layer according to Example 1. FIG. 8B is a chart of a scattering spectrum measured by oblique incidence X-ray scattering (incident angle (ω) = 0.30 degrees) using the resin sheet body with a conductor layer according to Example 1.

[0014] The resin sheet body, the resin sheet body with a conductor layer, and the multilayer circuit board of the present invention will be described below. However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied within the scope of the present invention. A combination of two or more of the individual desirable configurations of the present invention described in the following embodiments also constitutes the present invention.

[0015] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, scale, etc. may differ from those of the actual product.

[0016] Furthermore, 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 the second embodiment onwards, a description of the matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects resulting from similar configurations will not be mentioned in each embodiment.

[0017] (First embodiment) A resin sheet according to a first embodiment of the present invention has a first main surface and a second main surface opposite to the first main surface, and contains a wholly aromatic polyester, wherein the wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in a main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit, and when a scattering spectrum of the resin sheet is measured using a grazing incidence X-ray scattering method, at least one mole of the first structural unit is found to be greater than the number of moles of the second structural unit. In a portion of the resin sheet, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the region of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the sub-peak is in the region of 2θ = 26.0 degrees to 27.0 degrees, and in at least a portion 5 μm or more away from the first main surface toward the inside of the resin sheet, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the region of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the region of 2θ = 27.1 degrees to 28.0 degrees. The resin sheet according to the first embodiment of the present invention may include other configurations as long as it has the above characteristics and can achieve the effects of the present invention. Below, the components of the resin sheet according to the first embodiment of the present invention will be described in detail.

[0018] Fig. 1 is a cross-sectional view schematically illustrating an example of a resin sheet body according to a first embodiment of the present invention. The resin sheet body 10 shown in Fig. 1 has a first main surface 11 and a second main surface 12 opposite to the first main surface 11. As will be described in detail later, a conductor layer is disposed on the resin sheet body 10. In this case, the conductor layer is disposed on the first main surface 11 of the resin sheet body 10.

[0019] The thickness of the resin sheet 10 can be determined appropriately, but is preferably, for example, 10 μm or more and 500 μm or less.

[0020] When the scattering spectrum of the resin sheet 10 is measured using a grazing incidence X-ray scattering method, the obtained scattering spectrum shows that the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees, and the angle showing the maximum value of the subpeak is in the range of 2θ = 26.0 degrees to 27.0 degrees in at least a portion of the resin sheet 10 between the first main surface 11 and 5 μm. When such a scattering spectrum is obtained, it can be said that the intermolecular repulsion generated by the π orbital of the naphthalene ring is eliminated near the first main surface 11 of the resin sheet 10, and stress is minimized near the first main surface 11 of the resin sheet 10. Therefore, when a conductor layer is disposed on the first main surface 11 of the resin sheet 10, peeling of the conductor layer due to stress near the first main surface 11 of the resin sheet 10 can be prevented.

[0021] The resin sheet 10 exhibiting such a scattering spectrum can be obtained by producing a resin sheet using a wholly aromatic polyester that contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, and in which the number of moles of the first structural unit is greater than the number of moles of the second structural unit, and irradiating the main surface of the resin sheet with ultraviolet light under specified conditions. In other words, the resin sheet 10 can be said to be a resin sheet that has been modified by ultraviolet light irradiation.

[0022] When the scattering spectrum of the resin sheet 10 is measured using a grazing incidence X-ray scattering method, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees in at least a portion of the resin sheet 10 that is 5 μm or more away from the first main surface 11 of the resin sheet 10. This means that the resin sheet 10 that exhibits such a scattering spectrum does not receive much ultraviolet light and is hardly modified.

[0023] The scattering spectrum of a portion of the resin sheet body at a predetermined distance from the first main surface can be measured by adjusting the incidence angle (ω) of the X-rays in the grazing incidence X-ray scattering method. For example, when X-rays are irradiated onto the first main surface of the resin sheet body at an incidence angle (ω) of 0.18 degrees, the calculated penetration depth of the X-rays is 1.15 μm from the first main surface of the resin sheet body. Therefore, by measuring the scattering spectrum at an incidence angle (ω) of 0.18 degrees, the scattering spectrum of a portion of the resin sheet body at 1.15 μm from the first main surface of the resin sheet body can be measured. Furthermore, for example, when X-rays are irradiated onto the first main surface of the resin sheet body at an incidence angle (ω) of 0.30 degrees, the calculated penetration depth of the X-rays is 5.30 μm from the first main surface of the resin sheet body. Therefore, by measuring the scattering spectrum at an incidence angle (ω) of 0.30 degrees, the scattering spectrum of a portion of the resin sheet body at 5.30 μm from the first main surface of the resin sheet body can be measured.

[0024] The resin sheet 10 includes a wholly aromatic polyester. The wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit. Such a wholly aromatic polyester has a naphthalene ring-rich molecular structure, which can reduce dielectric loss. Therefore, when a multilayer circuit board is manufactured using the resin sheet 10, transmission loss can be reduced.

[0025] In the resin sheet 10, the ratio of the number of moles of the first constituent units to the number of moles of the second constituent units ([number of moles of first constituent units] / [number of moles of second constituent units]) is preferably greater than 1.0 and not more than 9.0, and more preferably not less than 1.5 and not more than 4.0. With such a ratio, transmission loss can be further reduced when a multilayer circuit board is manufactured using the resin sheet 10.

[0026] The number of moles of the first structural unit and the number of moles of the second structural unit in the resin sheet 10 can be measured by reactive pyrolysis-GC / MS. More specifically, the resin is decomposed using tetramethylammonium hydroxide as a reactive pyrolysis reagent, and the ratio of the number of moles can be calculated by quantifying the peaks of structural units having naphthalene tubes and structural units having benzene tubes using reactive pyrolysis-GC / MS. The GC / MS analyzer can be a Multi-Shot Pyrolyzer EGA / PY-3030D manufactured by Shimadzu Corporation.

[0027] In the resin sheet 10, the proportion of the second structural unit in the structural units constituting the main chain of the wholly aromatic polyester is preferably 20% or more and less than 50%. When the surface of a resin sheet made using a wholly aromatic polyester is modified by ultraviolet irradiation, the locations where benzene rings are continuous serve as the starting points for modification. When the proportion of the second structural unit is within the above range, the main surface of the resin sheet is suitably modified by ultraviolet irradiation.

[0028] The wholly aromatic polyester is preferably a liquid crystal polymer, and more preferably a thermotropic liquid crystal polymer. The wholly aromatic polyester material is preferably a block copolymer with parahydroxybenzoic acid, 2,6-hydroxynaphthoic acid, hydroquinone, 4,4-dihydroxybiphenyl, 2,6-naphthalenedicarboxylic acid, terephthalic acid, or isophthalic acid. Note that, in terms of water absorption, the wholly aromatic polyester in the resin sheet according to the first embodiment of the present invention preferably does not have an amide bond.

[0029] The wholly aromatic polyester is preferably heated to 400°C in an inert atmosphere, cooled to room temperature at a temperature decrease rate of 40°C / min or more, and then heated again at a temperature increase rate of 40°C / min while being measured using a differential scanning calorimeter, and the endothermic peak temperature exceeds 310°C. If the endothermic peak temperature exceeds 310°C, the heat resistance of a resin sheet containing the wholly aromatic polyester is improved. Furthermore, when a circuit board is produced using the resin sheet according to the first embodiment of the present invention, the circuit board is less likely to deform during solder mounting, such as a reflow process.

[0030] For example, in the case of a combination of parahydroxybenzoic acid and 4,6-hydroxynaphthoic acid, the endothermic peak temperature of the wholly aromatic polyester exceeds 310°C when the 4,6-hydroxynaphthoic acid content is 70% by mass or more. However, the monomer combination is not limited to this. The endothermic peak temperature of the wholly aromatic polyester is preferably 350°C or less. From the viewpoint of molding a resin sheet, the endothermic peak temperature is preferably lower than the decomposition temperature of the wholly aromatic polyester.

[0031] Next, an example of a method for producing a resin sheet body according to the first embodiment of the present invention will be described. The example of the method for producing a resin sheet body according to the first embodiment of the present invention may include, for example, a molding step of molding a sheet-like material from a wholly aromatic polyester and an ultraviolet irradiation step of irradiating ultraviolet rays onto the surface of the sheet-like material.

[0032] <Molding step> In this step, a monomer having a naphthalene ring and a functional group capable of forming an ester bond and a monomer having a benzene ring and a functional group capable of forming an ester bond are polymerized via an ester bond to produce a wholly aromatic polyester. At this time, the monomers are blended so that in the wholly aromatic polyester produced, the number of moles of the first structural unit having a naphthalene ring is greater than the number of moles of the second structural unit having a benzene ring.

[0033] Next, the wholly aromatic polyester is molded into a sheet to produce a sheet-like product. In this step, for example, a melt extrusion molding method can be used. Specifically, the melt of the wholly aromatic polyester may be directly molded into a sheet-like product by a conventionally known method such as a T-die method or an inflation method.

[0034] <Ultraviolet Irradiation Step> In this step, ultraviolet light is irradiated onto the first main surface of a sheet-like material to produce a resin sheet body. The ultraviolet irradiation conditions are adjusted so that the produced resin sheet body has the following characteristics. Specifically, when the scattering spectrum of the produced resin sheet body is measured using grazing incidence X-ray scattering, the obtained scattering spectrum has a main peak maximum angle in the range of 2θ = 18.0 degrees to 19.0 degrees and a sub-peak maximum angle in the range of 2θ = 26.0 degrees to 27.0 degrees in at least a portion of the resin sheet body extending from the first main surface to a distance of 5 μm inward, and the ultraviolet irradiation conditions are adjusted so that the obtained scattering spectrum has a main peak maximum angle in the range of 2θ = 19.1 degrees to 20.0 degrees and a sub-peak maximum angle in the range of 2θ = 27.1 degrees to 28.0 degrees in at least a portion of the resin sheet body extending from the first main surface to a distance of 5 μm or more inward.

[0035] The preferred ultraviolet irradiation conditions are as follows.

[0036] Ultraviolet rays are mainly classified into short-wavelength ultraviolet rays of 290 nm or less, medium-wavelength ultraviolet rays of 291 to 320 nm, and long-wavelength ultraviolet rays of 321 to 400 nm. In this process, at least short-wavelength ultraviolet rays are irradiated onto one main surface of the sheet-like material. This is because it is difficult to sufficiently modify one main surface of the sheet-like material with medium- and long-wavelength ultraviolet rays alone. However, as long as the ultraviolet rays to be irradiated include short-wavelength ultraviolet rays, those containing medium-wavelength ultraviolet rays or long-wavelength ultraviolet rays can also be used. Furthermore, those containing light rays other than ultraviolet rays may also be used.

[0037] The ultraviolet irradiation device to be used is not particularly limited as long as it can irradiate short wavelength ultraviolet light, but for example, a low pressure mercury lamp with a dominant wavelength of 185 nm and 254 nm, or a high pressure mercury lamp with a dominant wavelength of 254 nm and 365 nm is preferable because it is easy to handle. Also, a KrCl excimer lamp with a dominant wavelength of 222 nm, or a Xe excimer lamp with a dominant wavelength of 172 nm are preferable. ２ Excimer lamps and Kr ２ Excimer lamp, 126 nm Ar ２ An excimer lamp or the like may also be used, but since ultraviolet light of 230 nm or less is easily absorbed by oxygen and irradiation in air is inefficient, when using such a device, irradiation in a nitrogen environment or a vacuum environment is preferred.

[0038] The cumulative light amount of the short-wavelength ultraviolet light irradiated in this step is 500 to 2000 mJ / cm ２ The cumulative light amount of short-wavelength ultraviolet light is preferably 500 mJ / cm ２ If the total amount of short-wavelength ultraviolet light is less than 2000 mJ / cm, sufficient effect may not be obtained. ２ If the amount of light exceeds this limit, the sheet-like material may be deformed or its strength may be reduced. ２ Since the integrated light quantity is the product of the UV radiation intensity and the irradiation time (seconds), the integrated light quantity can be adjusted by adjusting the intensity of the UV radiation used and the irradiation time.

[0039] Furthermore, when irradiating ultraviolet rays, it is necessary to control the temperature of the sheet-like material. For example, if the temperature of the sheet-like material becomes too high, the sheet-like material may deform and wrinkle. The temperature of the sheet-like material depends on the amount of ultraviolet light irradiated and the distance (mm) between the UV tube and the sheet-like material, so these also need to be controlled. The temperature of the sheet-like material can be appropriately determined depending on the type of wholly aromatic polyester, but it is preferable to set the temperature of the sheet-like material at a temperature of 80°C or higher and 180°C or lower, for example.

[0040] Through the above steps, the resin sheet body according to the first embodiment of the present invention can be manufactured.

[0041] (Modification of First Embodiment) Next, a resin sheet according to a modification of the first embodiment of the present invention will be described. The resin sheet according to the modification of the first embodiment of the present invention has a first main surface and a second main surface opposite to the first main surface, and contains a wholly aromatic polyester, wherein the wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, the number of moles of the first structural unit is greater than the number of moles of the second structural unit, and when a scattering spectrum is measured using a grazing incidence X-ray scattering method with an incident angle (ω) of 0.18 degrees with respect to the first main surface of the resin sheet, the maximum value of the main peak is a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 26.0 degrees to 27.0 degrees, and when the scattering spectrum is measured using an oblique incidence X-ray scattering method with an incident angle (ω) of 0.30 degrees with respect to the first main surface of the resin sheet body, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees.

[0042] As described above, a resin sheet is produced using a wholly aromatic polyester that contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, and in which the number of moles of the first structural unit is greater than the number of moles of the second structural unit. When the main surface of the resin sheet is irradiated with ultraviolet light under specified conditions, the vicinity of the main surface of the resin sheet is modified.

[0043] When X-rays are irradiated onto the first main surface of the resin sheet at an incident angle (ω) of 0.18 degrees, the calculated penetration depth of the X-rays is 1.15 μm from the first main surface of the resin sheet. Therefore, by measuring the scattering spectrum at an incident angle (ω) of 0.18 degrees, the scattering spectrum of the portion 1.152 μm from the first main surface of the resin sheet can be measured. In this scattering spectrum, if the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the subpeak is in the range of 2θ = 26.0 degrees to 27.0 degrees, this indicates that the vicinity of the first main surface of the resin sheet has been modified by ultraviolet light.

[0044] When such a scattering spectrum is obtained, it can be said that the intermolecular repulsive force generated by the π orbital of the naphthalene ring is eliminated near the first main surface 11 of the resin sheet body 10, and stress is minimized near the first main surface 11 of the resin sheet body 10. Therefore, when a conductor layer is disposed on the first main surface 11 of the resin sheet body 10, peeling of the conductor layer due to stress near the first main surface 11 of the resin sheet body 10 can be prevented.

[0045] Furthermore, when X-rays are irradiated with an incident angle (ω) of 0.30 degrees relative to the first main surface of the resin sheet, the calculated penetration depth of the X-rays is 5.30 μm from the first main surface of the resin sheet. Therefore, by measuring the scattering spectrum with an incident angle (ω) of 0.30 degrees, the scattering spectrum of the portion 5.30 μm from the first main surface of the resin sheet can be measured. In this scattering spectrum, if the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the subpeak is in the range of 2θ = 27.1 degrees to 28.0 degrees, this means that the ultraviolet light does not reach the interior of the resin sheet 10 very well, and the resin sheet 10 is hardly modified.

[0046] In addition, in the resin sheet body according to the modified example of the first embodiment of the present invention, the configuration other than that described above is preferably the same as the preferred configuration of the resin sheet body according to the first embodiment of the present invention.

[0047] Second Embodiment Next, a resin sheet body with a conductor layer according to a second embodiment of the present invention will be described. Fig. 2 is a cross-sectional view schematically showing one example of a resin sheet body with a conductor layer according to the second embodiment of the present invention. The resin sheet body with a conductor layer 1 according to the second embodiment of the present invention shown in Fig. 2 includes the resin sheet body 10 according to the first embodiment of the present invention and a conductor layer 20 arranged on a first main surface 11 of the resin sheet body 10.

[0048] The resin sheet body included in the conductor layer-attached resin sheet body according to the second embodiment of the present invention may be a resin sheet body according to a modified example of the first embodiment of the present invention.

[0049] As described above, the vicinity of the first main surface 11 of the resin sheet body 10 is modified by ultraviolet irradiation, and it can be said that stress is minimized. Therefore, when the conductor layer 20 is disposed on the first main surface 11 of the resin sheet body 10, peeling of the conductor layer 20 due to stress in the vicinity of the first main surface 11 of the resin sheet body 10 can be prevented.

[0050] In the resin sheet body with a conductor layer according to the second embodiment of the present invention, the conductor layer is preferably a metal foil. Furthermore, the metal foil may be copper foil, copper alloy foil, silver foil, aluminum foil, or the like. Among these, copper foil is preferred. When the conductor layer is a metal foil, the resin sheet body and the metal foil can be bonded by placing the metal foil on the first main surface of the resin sheet body according to the first embodiment of the present invention and applying heat and pressure, thereby manufacturing the resin sheet body with a conductor layer according to the second embodiment of the present invention.

[0051] The conditions for the heating and pressing are not particularly limited, but may be, for example, 250° C. or higher and 350° C. or lower, 1.0 MPa or higher and 10.0 MPa or lower, and 1 second or higher and 20 minutes or shorter.

[0052] Even if such heating and pressurization are performed, the scattering spectrum of the resin sheet body measured by grazing incidence X-ray scattering does not change. Therefore, whether or not a certain resin sheet body with a conductor layer is the resin sheet body with a conductor layer according to the second embodiment of the present invention can be determined, for example, by the following method.

[0053] That is, the conductor layer of a certain conductor layer-equipped resin sheet body is removed by etching or the like. Next, X-rays are irradiated at a predetermined angle to the first main surface of the remaining resin sheet body to measure the scattering spectrum. Furthermore, when the conductor layer-equipped resin sheet body is part of a multilayer circuit board, the resist material or coverlay material on the surface of the board may be removed with a solvent or mechanically to expose the conductor layer, and then the conductor layer (conductor circuit pattern) may be etched away using a conventionally known etching solution such as an aqueous ferric chloride solution.

[0054] When a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 26.0 degrees to 27.0 degrees in at least a portion of the resin sheet body within 5 μm inward from the first main surface of the resin sheet body, and when a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees in at least a portion of the resin sheet body 5 μm or more inward from the first main surface of the resin sheet body, the resin sheet body with a conductor layer can be determined to be a resin sheet body with a conductor layer according to the second embodiment of the present invention.

[0055] Alternatively, when a scattering spectrum is measured with an incident angle (ω) of 0.18 degrees relative to the first main surface of the resin sheet body, if a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 26.0 degrees to 27.0 degrees, or when a scattering spectrum is measured with an incident angle (ω) of 0.30 degrees relative to the first main surface of the resin sheet body, if a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees, then the resin sheet body with a conductor layer can be determined to be a resin sheet body with a conductor layer according to the second embodiment of the present invention.

[0056] In the resin sheet body with a conductor layer according to the second embodiment of the present invention, the thickness of the conductor layer is not particularly limited, but is preferably 1 μm or more and 70 μm or less.

[0057] In the conductor layer-equipped resin sheet body according to the second embodiment of the present invention, the ten-point mean roughness (Rzjis) of the main surface of the conductor layer on the side disposed on the first main surface of the resin sheet body is preferably 2.0 μm or less, and more preferably 0.1 μm or more and 1.5 μm or less. When the ten-point mean roughness (Rzjis) of the main surface of the conductor layer is 2.0 μm or less, the conductor skin loss can be reduced, thereby reducing the transmission loss in a multilayer circuit board manufactured using the conductor layer-equipped resin sheet body according to the second embodiment of the present invention. Furthermore, a roughened surface having a ten-point mean roughness (Rzjis) of 2.0 μm or less can be easily formed. Furthermore, when the ten-point mean roughness (Rzjis) of the main surface of the conductor layer is 2.0 μm or less, residue is less likely to be left behind when removing a portion of the conductive layer by etching or the like. The ten-point mean roughness (Rzjis) refers to the ten-point mean roughness defined in JIS B 0601-2001.

[0058] Generally, if the ten-point average roughness (Rzjis) of the main surface of the conductor layer is low, the adhesive strength (peel strength) between the conductor layer and the resin sheet body is reduced. However, as described above, in the conductor layer-equipped resin sheet body according to the second embodiment of the present invention, the first main surface of the resin sheet body is modified by ultraviolet light. Therefore, in the conductor layer-equipped resin sheet body according to the second embodiment of the present invention, even if the ten-point average roughness (Rzjis) of the main surface of the conductor layer is 2.0 μm or less, the adhesive strength (peel strength) between the conductor layer and the resin sheet body is sufficiently high.

[0059] Third Embodiment Next, a multilayer circuit board according to a third embodiment of the present invention will be described. The multilayer circuit board according to the third embodiment of the present invention is a multilayer circuit board including the resin sheet body with a conductor layer according to the second embodiment of the present invention.

[0060] That is, a multilayer circuit board according to a third embodiment of the present invention has a first main surface and a second main surface opposite to the first main surface, and comprises a resin sheet body with a conductor layer including a resin sheet body containing a wholly aromatic polyester and a conductor layer arranged on the first main surface, wherein the wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit, and when a scattering spectrum of the resin sheet body is measured using a grazing incidence X-ray scattering method, In at least a portion of the region up to 5 μm away from the first main surface of the resin sheet, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the region of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the sub-peak is in the region of 2θ = 26.0 degrees to 27.0 degrees, and in at least a portion of the region 5 μm or more away from the first main surface of the resin sheet, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the region of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the region of 2θ = 27.1 degrees to 28.0 degrees.

[0061] Alternatively, a multilayer circuit board according to a third embodiment of the present invention has a first main surface and a second main surface opposite the first main surface, and comprises a resin sheet body with a conductor layer including a resin sheet body containing a wholly aromatic polyester and a conductor layer disposed on the first main surface, wherein the wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit, and a scattering spectrum is measured using a grazing incidence X-ray scattering method with an incident angle (ω) of 0.18 degrees with respect to the first main surface of the resin sheet body. When the scattering spectrum is measured using an oblique incidence X-ray scattering method with an incident angle (ω) of 0.30 degrees relative to the first main surface of the resin sheet, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees.

[0062] The multilayer circuit board according to the third embodiment of the present invention may include any other substrates as long as it includes at least one resin sheet body with a conductor layer according to the second embodiment of the present invention.

[0063] The multilayer circuit board according to the third embodiment of the present invention is preferably a multilayer circuit board in which a plurality of conductor layer-equipped resin sheets according to the second embodiment of the present invention are stacked.

[0064] A multilayer circuit board according to a third embodiment of the present invention in which a plurality of conductor layer-equipped resin sheet bodies according to the second embodiment of the present invention are stacked will be described with reference to the drawings.

[0065] Fig. 3 is a cross-sectional view schematically showing an example of a multilayer circuit board according to a third embodiment of the present invention. The multilayer circuit board 2a shown in Fig. 3 includes a conductor layer-equipped resin sheet body 1a in which a conductor layer 20a is arranged on a first main surface 11a of a resin sheet body 10a, and a conductor layer-equipped resin sheet body 1b in which a conductor layer 20b is arranged on a first main surface 11b of a resin sheet body 10b. Both the conductor layer-equipped resin sheet body 1a and the conductor layer-equipped resin sheet body 1b are conductor layer-equipped resin sheets according to the second embodiment of the present invention.

[0066] As shown in FIG. 3, in the multilayer circuit board 2a, the resin sheet body 10a and the resin sheet body 10b are stacked so that the second main surface 12a and the second main surface 12b thereof are in contact with each other.

[0067] The multilayer circuit board 2a can be produced by stacking the conductor layer-equipped resin sheet body 1a and the conductor layer-equipped resin sheet body 1b in the above-mentioned arrangement and applying heat and pressure by vacuum hot pressing. Conventionally known methods can be used as the conditions for the vacuum hot pressing.

[0068] Fig. 4 is a cross-sectional view schematically showing another example of a multilayer circuit board according to the third embodiment of the present invention. A multilayer circuit board 2b shown in Fig. 4 includes a conductor layer-equipped resin sheet body 1a in which a conductor layer 20a is arranged on the first main surface 11a of a resin sheet body 10a, a conductor layer-equipped resin sheet body 1b in which a conductor layer 20b is arranged on the first main surface 11b of a resin sheet body 10b, and a conductor layer-equipped resin sheet body 1c in which a conductor layer 20c is arranged on the first main surface 11c of a resin sheet body 10c. The conductor layer-equipped resin sheet body 1a, the conductor layer-equipped resin sheet body 1b, and the conductor layer-equipped resin sheet body 1c are all conductor layer-equipped resin sheets according to the second embodiment of the present invention.

[0069] 4, in the multilayer circuit board 2b, the resin sheet bodies 10a and 10c are stacked so that the second main surface 12a of the resin sheet body 10a and the second main surface 12b of the resin sheet body 10b are in contact with each other, and the conductor layer 20a of the resin sheet body 10a and the second main surface 12c of the resin sheet body 10c are stacked so that they are in contact with each other.

[0070] The multilayer circuit board 2b can be manufactured by stacking the conductor layer-equipped resin sheet body 1a, the conductor layer-equipped resin sheet body 1b, and the conductor layer-equipped resin sheet body 1c in the above-mentioned arrangement, and then heating and pressurizing them using a vacuum hot press.

[0071] Fig. 5 is a cross-sectional view schematically illustrating another example of a multilayer circuit board according to the third embodiment of the present invention. The multilayer circuit board 2c shown in Fig. 5 differs from the multilayer circuit board 2a in that a conductor circuit pattern 30 is disposed between the second main surface 12a of the resin sheet body 10a and the second main surface 12b of the resin sheet body 10b. Note that a conventionally known conductor circuit pattern 30 can be used as the conductor circuit pattern 30.

[0072] Such a multilayer circuit board 2c can be manufactured by arranging a conductor circuit pattern 30 on the second main surface 12a of the resin sheet body 10a or the second main surface 12b of the resin sheet body 10b, stacking the resin sheet body 1a with a conductor layer and the resin sheet body 1b with a conductor layer in the above-mentioned arrangement, and heating and pressurizing them using a vacuum hot press.

[0073] Fig. 6 is a cross-sectional view schematically illustrating another example of a multilayer circuit board according to the third embodiment of the present invention. The multilayer circuit board 2d shown in Fig. 6 differs from the multilayer circuit board 2c in that via conductors 40 connecting the conductor layer 20a and the conductor circuit pattern 30 are arranged so as to penetrate the resin sheet body 10a. Conventionally known via conductors 40 may be used.

[0074] Such a multilayer circuit board 2d can be manufactured by the following method. First, via conductors 40 are formed in the conductor-layer-equipped resin sheet body 1a so as to penetrate the resin sheet body 10a and connect to the conductor layer 20a. A conductor circuit pattern 30 is also arranged on the second main surface 12b of the resin sheet body 10b. The conductor-layer-equipped resin sheet body 1a and the conductor-layer-equipped resin sheet body 1b are then stacked on top of each other so that the conductor circuit pattern 30 and the via conductors 40 are in contact with each other, and the resulting stack is heated and pressurized by a vacuum hot press. This allows the multilayer circuit board 2d to be manufactured.

[0075] 7 is a cross-sectional view schematically illustrating another example of a multilayer circuit board according to the third embodiment of the present invention. The multilayer circuit board 2e shown in FIG. 7 differs from the multilayer circuit board 2a in that via conductors 40 connecting the conductor layers 20a and 20b are arranged to penetrate the resin sheet bodies 10a and 10b. Conventionally known via conductors 40 may be used.

[0076] Such a multilayer circuit board 2e can be manufactured by the following method. First, via conductors 40 are formed in the conductor-layer-equipped resin sheet body 1a so as to penetrate the resin sheet body 10a and connect to the conductor layer 20a. At this time, the length of the via conductors 40 protruding from the second main surface 12a of the resin sheet body 10a is set to a length that allows them to penetrate the resin sheet body 10b and contact the conductor layer 20b. The conductor-layer-equipped resin sheet body 1a and the conductor-layer-equipped resin sheet body 1b are then stacked on top of each other, and heated and pressurized by a vacuum hot press so that the via conductors 40 penetrate the resin sheet body 10b and contact the conductor layer 20b. This completes the manufacture of the multilayer circuit board 2e.

[0077] This specification describes the following:

[0078] The present invention (1) provides a resin sheet having a first main surface and a second main surface opposite to the first main surface, the resin sheet containing a wholly aromatic polyester, the wholly aromatic polyester containing a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in a main chain, the number of moles of the first structural unit being greater than the number of moles of the second structural unit, and when a scattering spectrum of the resin sheet is measured using a grazing incidence X-ray scattering method, a main peak is formed in at least a part of the area up to 5 μm inward from the first main surface of the resin sheet. a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the region of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the sub-peak is in the region of 2θ = 26.0 degrees to 27.0 degrees, and in at least a portion of the resin sheet that is 5 μm or more away inward from the first main surface of the resin sheet, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the region of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the region of 2θ = 27.1 degrees to 28.0 degrees.

[0079] The present invention (2) is a resin sheet having a first main surface and a second main surface opposite the first main surface, and comprising a wholly aromatic polyester, wherein the wholly aromatic polyester comprises a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in a main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit, and when a scattering spectrum is measured using a grazing incidence X-ray scattering method with an incident angle (ω) of 0.18 degrees with respect to the first main surface of the resin sheet, the angle showing the maximum value of the main peak is 2θ=18.0°. and a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the subpeak is in the range of 2θ = 27.1 degrees to 28.0 degrees, and when the scattering spectrum is measured using oblique incidence X-ray scattering at an incident angle (ω) of 0.30 degrees with respect to the first main surface of the resin sheet, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the subpeak is in the range of 2θ = 27.1 degrees to 28.0 degrees.

[0080] The present invention (3) is a resin sheet body with a conductor layer, characterized by comprising the resin sheet body according to the present invention (1) or (2) and a conductor layer disposed on the first main surface of the resin sheet body.

[0081] The present invention (4) is the resin sheet body with a conductor layer according to the present invention (3), wherein the conductor layer is a metal foil.

[0082] The present invention (5) is the resin sheet body with a conductor layer according to the present invention (4), wherein the metal foil is a copper foil.

[0083] The present invention (6) is the resin sheet body with a conductor layer according to any one of the present inventions (3) to (5), wherein the ten-point average roughness (Rzjis) of the main surface of the conductor layer on the side arranged on the first main surface is 2.0 μm or less.

[0084] The present invention (7) provides a resin sheet body with a conductor layer, which has a first main surface and a second main surface opposite to the first main surface, and includes a resin sheet body containing a wholly aromatic polyester, and a conductor layer disposed on the first main surface, wherein the wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit, and when a scattering spectrum of the resin sheet body is measured using a grazing incidence X-ray scattering method, a small number of moles of the first structural unit are present within 5 μm from the first main surface of the resin sheet body toward the inside. a scattering spectrum is obtained in at least a portion of the resin sheet body, in which the angle showing the maximum value of the main peak is in the region of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the sub-peak is in the region of 2θ = 26.0 degrees to 27.0 degrees, and a scattering spectrum is obtained in at least a portion of the resin sheet body, in which the angle showing the maximum value of the main peak is in the region of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the region of 2θ = 27.1 degrees to 28.0 degrees, at least in a portion of the resin sheet body, in which the angle showing the maximum value of the main peak is in the region of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the region of 2θ = 27.1 degrees to 28.0 degrees.

[0085] The present invention (8) provides a resin sheet body with a conductor layer, which has a first main surface and a second main surface opposite to the first main surface, and includes a resin sheet body containing a wholly aromatic polyester, and a conductor layer disposed on the first main surface, wherein the wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit, and when a scattering spectrum is measured using a grazing incidence X-ray scattering method with an incident angle (ω) of 0.18 degrees with respect to the first main surface of the resin sheet body, the maximum of a main peak is a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 26.0 degrees to 27.0 degrees, and when the scattering spectrum is measured using oblique incidence X-ray scattering at an incident angle (ω) of 0.30 degrees with respect to the first main surface of the resin sheet, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees.

[0086] Examples will be given below that more specifically disclose the resin sheet body of the present invention, the resin sheet body with a conductor layer of the present invention, and the multilayer circuit board of the present invention, but the present invention is not limited to the following examples.

[0087] Example 1 A wholly aromatic polyester with a high HNA ratio (Tm = 330°C) was produced by melt-polymerizing a monomer ratio of p-hydroxybenzoic acid (HBA):6-hydroxy-2-naphthoic acid (HNA) = 3:7 at 340°C. This wholly aromatic polyester was melt-extruded into a sheet and then transversely stretched to produce a sheet-like product (thickness 50 μm) that was equi-oriented in the in-plane direction.

[0088] Next, the first main surface of the sheet-like material was irradiated with ultraviolet light using a high-pressure UV treatment device. At this time, the distance between the high-pressure UV tube and the sheet-like material was kept at 170 mm, and the integrated light amount of ultraviolet light having a wavelength of 250 to 270 nm was 1185 mJ / cm. ２The temperature of the first main surface of the sheet-like material during irradiation was 103°C.

[0089] Through the above steps, a resin sheet according to Example 1 was produced.

[0090] Next, a 12 μm thick electrolytic copper foil was prepared, and one main surface of the electrolytic copper foil was roughened so that the ten-point average roughness Rzjis was 1.8 μm. The resin sheet body according to Example 1 and the electrolytic copper foil were then superimposed such that the first main surface of the resin sheet body according to Example 1 faced the roughened main surface of the electrolytic copper foil. The resin sheet body according to Example 1 and the electrolytic copper foil were then heated and pressed at 300°C and 3 MPa using a pair of roll laminators to bond the resin sheet body according to Example 1 and the electrolytic copper foil together to form a laminate. The laminate was then heat-treated at 250°C for 10 minutes to produce a resin sheet body with a conductor layer according to Example 1.

[0091] (Example 2) A resin sheet body and a resin sheet body with a conductor layer according to Example 2 were prepared in the same manner as in Example 1, except that the conditions for irradiating ultraviolet light onto the first main surface of the sheet-like material were changed as shown in Table 1.

[0092] Comparative Example 1 A resin sheet body and a resin sheet body with a conductor layer according to Comparative Example 1 were produced in the same manner as in Example 1, except that the first main surface of the sheet-like material was not irradiated with ultraviolet light.

[0093] (Comparative Example 2) A resin sheet body and a resin sheet body with a conductor layer according to Comparative Example 2 were prepared in the same manner as in Example 1, except that the conditions for irradiating ultraviolet light onto the first main surface of the sheet-like material were changed as shown in Table 1.

[0094] (Measurement of Scattering Spectra by Grazing Incidence X-ray Scattering) The conductor layer of each resin sheet with a conductor layer according to each Example and Comparative Example was etched away using a ferric chloride aqueous solution. After etching, the conductor layer was washed with water and dried to obtain a resin sheet. The resulting resin sheet was subjected to scattering spectrum measurement by grazing incidence X-ray scattering using a small-angle / wide-angle X-ray scattering / diffractometer (model number: NANOPIX, manufacturer: Rigaku Corporation). In measuring the scattering spectrum, a resin sheet prepared as a measurement sample was placed on the stage of an analyzer, and the inclination of the sample was adjusted and fixed so that it was parallel to the X-rays. The X-ray incident angle (ω) was then adjusted to 0.18 degrees and 0.30 degrees relative to the first main surface of the resin sheet. This allowed for the scattering spectrum to be measured in the regions 1.15 μm and 5.30 μm inward from the first main surface of each resin sheet. Scattering spectrum charts obtained using the conductor layer-equipped resin sheet body of Example 1 are shown in Figures 8A and 8B as representative examples. Figure 8A is a scattering spectrum chart measured by oblique incidence X-ray scattering (incidence angle (ω) = 0.18 degrees) using the conductor layer-equipped resin sheet body of Example 1. Figure 8B is a scattering spectrum chart measured by oblique incidence X-ray scattering (incidence angle (ω) = 0.30 degrees) using the conductor layer-equipped resin sheet body of Example 1. In Figures 8A and 8B, the scattering spectrum charts are shown with the vertical axis representing intensity and the horizontal axis representing diffraction angle (2θ).

[0095] The angle showing the maximum value of the main peak and the angle showing the maximum value of the sub-peak were read from the obtained scattering spectrum. The results are shown in Table 1.

[0096]

[0097] As shown in Table 1, in the scattering spectrum obtained using the resin sheet with a conductor layer according to each Example, when the incident angle (ω) was 0.18 degrees, the angle showing the maximum value of the main peak was in the range of 2θ = 18.0 to 19.0 degrees, and the angle showing the maximum value of the subpeak was in the range of 2θ = 26.0 to 27.0 degrees. When the incident angle (ω) was 0.30 degrees, the angle showing the maximum value of the main peak was in the range of 2θ = 19.1 to 20.0 degrees, and the angle showing the maximum value of the subpeak was in the range of 2θ = 27.1 to 28.0 degrees.

[0098] Furthermore, as shown in Table 1, in the scattering spectra obtained using the resin sheet body with a conductor layer according to each comparative example, when the incident angle (ω) was set to 0.18 degrees, it was found that the angle showing the maximum value of the main peak was not in the region of 2θ = 18.0 degrees to 19.0 degrees, and the angle showing the maximum value of the sub-peak was not in the region of 2θ = 26.0 degrees to 27.0 degrees.

[0099] (Measurement of Peel Strength) For the resin sheet body with a conductor layer according to each Example and Comparative Example, the peel strength between the resin sheet body and the conductor layer was measured by performing a 90° peel test in accordance with JIS C 6471. The results are shown in Table 1.

[0100] As shown in Table 1, it was found that the resin sheet body with a conductor layer according to each example had a high peel strength between the conductor layer and the resin sheet body.

[0101] In the resin sheet body with a conductor layer according to each example, the peel strength between the conductor layer and the resin sheet body is high because the vicinity of the first main surface of the resin sheet body is modified by ultraviolet light. In the resin sheet body with a conductor layer according to each comparative example, the peel strength between the conductor layer and the resin sheet body is low because the vicinity of the first main surface of the resin sheet body is not modified by ultraviolet light or is not sufficiently modified by ultraviolet light.

[0102] From the above results, it was found that when the scattering spectrum of a resin sheet body is measured using oblique incidence X-ray scattering, if a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 26.0 degrees to 27.0 degrees in at least a portion of the region from the first main surface of the resin sheet body to a distance of 5 μm inward, and if a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees in at least a portion of the region 5 μm or more away from the first main surface of the resin sheet body to a distance of 5 μm inward, the peel strength between the conductor layer of a resin sheet body with a conductor layer produced using the resin sheet body and the resin sheet body is high.

[0103] Example 3 Two resin sheets with conductor layers according to Example 1 were prepared. An etching resist for forming a circuit pattern was formed on each conductor layer, and a conductor circuit pattern was formed using an aqueous ferric chloride solution. Next, one resin sheet with conductor layers was placed on top of the other resin sheet with conductor layers. This was done so that the conductor circuit pattern formed on one resin sheet with conductor layers was in contact with the resin sheet of the other resin sheet with conductor layers. Heating and pressurizing were then performed in a vacuum press at 280°C and 3 MPa for 15 minutes to produce a multilayer circuit board according to Example 3.

[0104] (Measurement of scattering spectrum by grazing incidence X-ray scattering method) The conductor circuit pattern formed on the upper layer of the multilayer circuit board of Example 3 was etched away using an aqueous ferric chloride solution. Thereafter, the scattering spectrum was measured in the same manner as in the "Measurement of scattering spectrum by grazing incidence X-ray scattering method" described above. The results are shown in Table 2.

[0105]

[0106] As shown in Table 2, when a multilayer circuit board was produced by heating and pressing the resin sheet body with a conductor layer according to Example 1, it was found that the peak of the scattering spectrum of the resin sheet body with a conductor layer after heating and pressing shifted slightly.

[0107] (Measurement of Peel Strength) A multilayer circuit board according to Example 3 was prepared separately. Then, the resin sheet with a conductor layer arranged on the upper layer of the multilayer circuit board according to Example 3 was peeled off, and the resin sheet with a conductor layer was subjected to a 90° peel test in accordance with JIS C 6471 to measure the peel strength between the resin sheet and the conductor circuit pattern. As a result, the peel strength was 0.7 kN / m.

[0108] These results demonstrate that even when a multilayer circuit board is fabricated using the resin sheet body with a conductor layer according to Example 1, the peel strength between the conductor layer (conductor circuit pattern) and the resin sheet body is sufficiently high.

[0109] DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c Resin sheet body with conductor layer 2a, 2b, 2c, 2d, 2e Multilayer circuit board 10, 10a, 10b, 10c Resin sheet body 11, 11a, 11b, 11c First main surface 12, 12a, 12b, 12c Second main surface 20, 20a, 20b, 20c Conductor layer 30 Conductive circuit pattern 40 Via conductor

Claims

1. A resin sheet having a first main surface and a second main surface opposite the first main surface, and comprising a wholly aromatic polyester, wherein the wholly aromatic polyester comprises a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit; when the scattering spectrum of the resin sheet is measured using a grazing incidence X-ray scattering method, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees, and the angle showing the maximum value of the sub-peak is in the range of 2θ = 26.0 degrees to 27.0 degrees, in at least a part of the area up to 5 μm inward from the first main surface of the resin sheet; A resin sheet body characterized in that, in at least a portion of the resin sheet body that is 5 μm or more away from the first main surface toward the inside, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees, and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees.

2. A resin sheet having a first main surface and a second main surface opposite the first main surface, and comprising a wholly aromatic polyester, wherein the wholly aromatic polyester comprises a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit; when a scattering spectrum is measured using a grazing incidence X-ray scattering method with an incident angle (ω) of 0.18 degrees with respect to the first main surface of the resin sheet, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees, and the angle showing the maximum value of the sub-peak is in the range of 2θ = 26.0 degrees to 27.0 degrees; A resin sheet body characterized in that, when a scattering spectrum is measured using an oblique incidence X-ray scattering method with an incident angle (ω) of 0.30 degrees relative to the first main surface of the resin sheet body, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees, and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees.

3. A resin sheet body with a conductor layer, comprising: the resin sheet body according to claim 1 or 2; and a conductor layer disposed on the first main surface of the resin sheet body.

4. The resin sheet with a conductor layer according to claim 3, wherein the conductor layer is a metal foil.

5. A resin sheet with a conductor layer according to claim 4, wherein the metal foil is copper foil.

6. A resin sheet body with a conductor layer according to any one of claims 3 to 5, wherein the ten-point average roughness (Rzjis) of the main surface of said conductor layer on the side arranged on said first main surface is 2.0 µm or less.

7. A resin sheet with a conductor layer, comprising a resin sheet having a first main surface and a second main surface opposite the first main surface, the resin sheet containing a wholly aromatic polyester, and a conductor layer disposed on the first main surface, wherein the wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit, and when the scattering spectrum of the resin sheet is measured using a grazing incidence X-ray scattering method, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees and the angle showing the maximum value of the sub-peak is in the range of 2θ = 26.0 degrees to 27.0 degrees in at least a part of the area extending from the first main surface of the resin sheet to 5 μm inward, A multilayer circuit board characterized in that, in at least a portion of the resin sheet body that is 5 μm or more away from the first main surface toward the inside, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees, and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees.

8. A resin sheet with a conductor layer, comprising a resin sheet having a first main surface and a second main surface opposite the first main surface, the resin sheet containing a wholly aromatic polyester, and a conductor layer disposed on the first main surface, wherein the wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in its main chain, and the number of moles of the first structural unit is greater than the number of moles of the second structural unit, and when a scattering spectrum is measured using an oblique incidence X-ray scattering method with an incident angle (ω) of 0.18 degrees with respect to the first main surface of the resin sheet, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 18.0 degrees to 19.0 degrees, and the angle showing the maximum value of the sub-peak is in the range of 2θ = 26.0 degrees to 27.0 degrees, A multilayer circuit board characterized in that, when a scattering spectrum is measured using an oblique incidence X-ray scattering method with an incident angle (ω) of 0.30 degrees relative to the first main surface of the resin sheet body, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 19.1 degrees to 20.0 degrees, and the angle showing the maximum value of the sub-peak is in the range of 2θ = 27.1 degrees to 28.0 degrees.

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