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

Abstract

Provided is a resin sheet body having sufficiently high surface tensile breaking strength.　A resin sheet body (10) according to the present invention has a first main surface (11) and a second main surface (12) facing the first main surface (11), and contains a wholly aromatic polyester, the resin sheet body being characterized in that: the wholly aromatic polyester contains, in a main chain, a first constituent unit having a benzene ring and a second constituent unit having a naphthalene ring; the number of moles of the first constituent unit is greater than the number of moles of the second constituent unit; when the scattering spectrum of the resin sheet body is measured using a grazing-incidence X-ray scattering method, in at least a portion separated by 5 µm or less from the first main surface toward the inner side of the resin sheet body, a scattering spectrum in which an angle indicating the maximum value of a main peak is in a region of 2θ = 20.0° to 21.0°, an angle indicating the maximum value of a first sub-peak is in a region of 2θ = 18.0° to 19.5°, and an angle indicating the maximum value of a second sub-peak is in a region of 2θ = 26.6° to 27.5° is obtained; and, in at least a portion separated by 5 µm or more from the first main surface toward the inner side of the resin sheet body, a scattering spectrum in which an angle indicating the maximum value of a main peak is in a region of 2θ = 19.1° to 20.0° and an angle indicating the maximum value of a sub-peak is in a region of 2θ = 27.6° to 29.0° is obtained.

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 body with a conductor layer) described in Patent Document 1, the thermoplastic liquid crystal polymer film does not have sufficient tensile breaking strength on the surface, and there was a problem that the metal foil was easily peeled off during processing when producing a multilayer circuit board.

[0006] The present invention has been made to solve the above problems, and an object of the present invention is to provide a resin sheet body having a surface with sufficiently high tensile breaking strength.

[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 benzene ring and a second structural unit having a naphthalene 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 angle showing the maximum value of the main peak is 2θ= The resin sheet is characterized in that 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, the angle showing the maximum value of the first sub-peak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second sub-peak is in the range of 2θ = 26.6 degrees to 27.5 degrees, and in at least a portion of the resin sheet 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 = 27.6 degrees to 29.0 degrees.

[0008] Another aspect of the resin sheet of the present invention 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 benzene ring and a second structural unit having a naphthalene 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, the angle showing the maximum value of the main peak is in the region of 2θ = 20.0 degrees to 21.0 degrees. a scattering spectrum is obtained in which the angle showing the maximum value of the first sub-peak is in the range of 2θ = 18.0 degrees to 19.5 degrees and the angle showing the maximum value of the second sub-peak is in the range of 2θ = 26.6 degrees to 27.5 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 = 27.6 degrees to 29.0 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 arranged on the first main surface, wherein the wholly aromatic polyester contains a first structural unit having a benzene ring and a second structural unit having a naphthalene 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, it is found that a main pin a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first sub-peak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second sub-peak is in the range of 2θ = 26.6 degrees to 27.5 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 = 27.6 degrees to 29.0 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 containing a first structural unit having a benzene ring and a second structural unit having a naphthalene ring in its main chain, the number of moles of the first structural unit being greater than the number of moles of the second structural unit, and the scattering spectrum of the resin sheet body measured using an oblique incidence X-ray scattering method with an incident angle (ω) of 0.18 degrees relative to the first main surface of the resin sheet body being such that the angle showing the maximum value of the main peak is 2θ=2 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, the angle showing the maximum value of the first sub-peak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second sub-peak is in the range of 2θ = 26.6 degrees to 27.5 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 = 27.6 degrees to 29.0 degrees.

[0012] According to the present invention, it is possible to provide a resin sheet having a surface with sufficiently high tensile strength at break.

[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. The wholly aromatic polyester contains a first structural unit having a benzene ring and a second structural unit having a naphthalene 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. When a scattering spectrum of the resin sheet is measured using a grazing incidence X-ray scattering method, the angle at which the maximum value of the main peak is reached is at least partially within a range of 5 μm from the first main surface of the resin sheet toward the inside. The resin sheet according to the first embodiment of the present invention is characterized in that a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first subpeak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second subpeak is in the range of 2θ = 26.6 degrees to 27.5 degrees, and in at least a portion of the resin sheet that is 5 μm or more away from the first main surface toward the inside, 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 = 27.6 degrees to 29.0 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. The components of the resin sheet according to the first embodiment of the present invention will be described in detail below.

[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 body 10 is measured using oblique incidence X-ray scattering, a scattering spectrum is obtained in which, in at least a portion of the area between the first main surface 11 of the resin sheet body 10 and 5 μm, the angle showing the maximum value of the main peak is in the range of 2θ = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first sub-peak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second sub-peak is in the range of 2θ = 26.6 degrees to 27.5 degrees.

[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 benzene ring and a second structural unit having a naphthalene 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 such a scattering spectrum is obtained, it can be said that the intermolecular repulsion caused by the π orbitals of the benzene rings is eliminated near the first main surface 11 of the resin sheet body 10, and that the stress near the first main surface 11 of the resin sheet body 10 is minimized. Furthermore, since a wholly aromatic polyester containing a large amount of first constituent units having benzene rings is used, the strength (tensile breaking strength) of the surface of the resin sheet body is increased. 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.

[0023] 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 = 27.6 degrees to 29.0 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.

[0024] 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.

[0025] The resin sheet 10 contains a wholly aromatic polyester. The wholly aromatic polyester contains a first structural unit having a benzene ring and a second structural unit having a naphthalene 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 molecular structure rich in benzene rings, so that the tensile breaking strength of the surface of the resin sheet 10 is sufficiently high. Therefore, when a multilayer circuit board is manufactured using the resin sheet 10, the conductor layer disposed on the resin sheet 10 is less likely to peel off.

[0026] Furthermore, wholly aromatic polyesters having a molecular structure rich in benzene rings have high heat resistance, and therefore, when a multilayer circuit board is manufactured using the resin sheet 10, the heat resistance of the multilayer circuit board can be improved.

[0027] Furthermore, the resin sheet 10 containing the wholly aromatic polyester having a benzene ring-rich molecular structure has high mechanical strength. In other words, the resin sheet 10 is not brittle and is easy to handle. Therefore, the resin sheet 10 has good processability.

[0028] In the resin sheet 10, the ratio of the number of moles of the first constituent unit to the number of moles of the second constituent unit ([number of moles of first constituent unit] / [number of moles of second constituent unit]) is preferably 7 / 3 or more, more preferably 7 / 3 or more and 9 / 1 or less, and even more preferably 7 / 3 or more and 8 / 2 or less. With such a ratio, when a multilayer circuit board is manufactured using the resin sheet 10, the conductor layer arranged on the resin sheet 10 becomes less likely to peel off. Furthermore, when the ratio of the number of moles of the first constituent unit to the number of moles of the second constituent unit is 7 / 3 or more, the Tm of the wholly aromatic polyester tends to be high. Therefore, the heat resistance of the resin sheet 10 is improved. Furthermore, the mechanical strength of the resin sheet 10 is increased, making it easier to handle.

[0029] 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 a benzene ring and the peaks of structural units having a naphthalene ring using reactive pyrolysis-GC / MS. The GC / MS analyzer that can be used is a Multi-Shot Pyrolyzer EGA / PY-3030D manufactured by Shimadzu Corporation.

[0030] In the resin sheet 10, the proportion of the second structural units in the structural units constituting the main chain of the wholly aromatic polyester is preferably 20% or more and less than 50%. When the proportion of the second structural units is within the above range, the proportion of naphthalene rings becomes an appropriate number, and when a multilayer circuit board is manufactured using the resin sheet 10, transmission loss can be reduced. Furthermore, when the proportion of the second structural units is within the above range, the proportion of naphthalene rings becomes an appropriate number, and the melting point of the wholly aromatic polyester can be appropriately lowered. This makes it easier to melt-process the wholly aromatic polyester.

[0031] 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.

[0032] 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.

[0033] 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 parahydroxybenzoic 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.

[0034] The resin sheet of the present invention preferably has the following parameters in the spectrum of Fourier transform infrared spectroscopy: That is, in the spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement on the first main surface of the resin sheet using Ge as a high refractive index medium, －１ Above, 1530cm －１ The area of ​​the first peak appearing in the following region is defined as the first peak area P1, and －１ Above, 1450cm －１ The area of ​​the second peak appearing in the following region is defined as the second peak area P2, and the ratio (P1 / P2) of the first peak area P1 to the second peak area P2 is defined as the first ratio R1. In the spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement on the first main surface of the resin sheet using ZnSe as a high refractive index medium, －１ Above, 1530cm －１ The area of ​​the third peak appearing in the following region is designated as the third peak area P3, and the area of ​​the third peak appearing in the following region is designated as the third peak area P3. －１ Above, 1450cm －１ When the area of ​​the fourth peak appearing in the following region is defined as a fourth peak area P4, and the ratio (P3 / P4) of the third peak area P3 to the fourth peak area P4 is defined as a second ratio R2, it is preferable that the following formulas (1) and (2) are satisfied: 0.83≦R1≦2.06 (1) 0.58≦R1 / R2≦1.09 (2)

[0035] The area of ​​each peak means the area enclosed by the straight lines connecting the outer tails of each peak in the spectrum obtained by Fourier transform infrared spectroscopy.

[0036] When a conductor layer is disposed on the first main surface of a resin sheet that satisfies the above formulas (1) and (2), the adhesiveness between the resin sheet and the conductor layer is improved. The principle behind this is as follows.

[0037] In the spectrum of Fourier transform infrared spectroscopy when total reflection measurement is performed using Ge as a high refractive index medium, －１ Above, 1530cm －１ The peaks appearing in the following region are due to the C-C stretching vibration of the aromatic ring, and are at 1400 cm －１ Above, 1450cm －１ The peaks appearing in the following region are peaks due to C-H deformation vibration. The smaller the first ratio R1 (i.e., the larger the second peak area P2), the more ester bonds in the wholly aromatic polyester are transferred to ketone groups. When the first ratio R1 satisfies the above formula (1), the degree to which the ester bonds are transferred to ketone groups falls within an appropriate range, making the first main surface of the resin sheet less susceptible to hydrolysis. Therefore, when a conductor layer is disposed on the first main surface of the resin sheet and heated and pressurized, the adhesive strength (peel strength) between the resin sheet and the conductor layer is increased.

[0038] In the spectrum of Fourier transform infrared spectroscopy when total reflection measurement is performed using ZnSe as a high refractive index medium, －１ Above, 1530cm －１ The peaks appearing in the following region are due to the C-C stretching vibration of the aromatic ring, and are at 1400 cm －１ Above, 1450cm －１ The peaks appearing in the following region are peaks due to C-H bending vibration. When the first ratio R1 / second ratio R2 satisfies the above formula (2), it means that an appropriate number of ester bonds have been transferred to ketone groups in the vicinity of the first main surface of the resin sheet. Therefore, when a conductor layer is placed on the first main surface of the resin sheet and heated and pressurized, the adhesive strength (peel strength) between the resin sheet and the conductor layer is increased.

[0039] As described above, the resin sheet of the present invention can be produced by irradiating the surface of a sheet-like material containing a wholly aromatic polyester with ultraviolet light to modify it. If the first ratio R1 / second ratio R2 is less than 0.58, the amount of ultraviolet light irradiation is too high, and the resin sheet may be deformed or its strength may be reduced. If the first ratio R1 / second ratio R2 is more than 1.09, the amount of ultraviolet light irradiation is too low, and the resin sheet may not be sufficiently modified near its first main surface, and the adhesive strength (peel strength) between the resin sheet and the conductor layer may be insufficient.

[0040] The "total reflection measurement method" in this specification will be described. First, two resin sheets are prepared, and each resin sheet is placed in an ATR (Attenuated Total Reflection) measurement device (model name: ATRPRO610X, manufacturer: JASCO Corporation). At this time, the first main surface of each resin sheet is brought into close contact with a high refractive index medium. Then, using a Fourier transform infrared spectrophotometer (model name: FT / IR-6X, manufacturer: JASCO Corporation), the total reflection measurement is performed at an incident angle of 45° and a measurement wavelength of 650 to 4000 cm. －１ The measurement is carried out 32 times in the range of 1000 to obtain a spectrum by Fourier transform infrared spectroscopy. The high refractive index medium is made of Ge or ZnSe.

[0041] 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.

[0042] <Molding step> In this step, a monomer having a benzene ring and a functional group capable of forming an ester bond and a monomer having a naphthalene 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 benzene ring is greater than the number of moles of the second structural unit having a naphthalene ring.

[0043] 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.

[0044] <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 = 20.0 to 21.0 degrees, a first sub-peak maximum angle in the range of 2θ = 18.0 to 19.5 degrees, and a second sub-peak maximum angle in the range of 2θ = 26.6 to 27.5 degrees in at least a portion of the resin sheet body extending inward from the first main surface, and a main peak maximum angle in the range of 2θ = 19.1 to 20.0 degrees, and a sub-peak maximum angle in the range of 2θ = 27.6 to 29.0 degrees in at least a portion of the resin sheet body extending inward from the first main surface, 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 to 20.0 degrees, and a sub-peak maximum angle in the range of 2θ = 27.6 to 29.0 degrees in at least a portion of the resin sheet body extending inward from the first main surface, and ...

[0045] The preferred ultraviolet irradiation conditions are as follows.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] Through the above steps, the resin sheet body according to the first embodiment of the present invention can be manufactured.

[0051] (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 benzene ring and a second structural unit having a naphthalene 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 angle showing the maximum value of the main peak is 2θ = 20.0 degrees to 21.0 degrees. a scattering spectrum is obtained in which the angle showing the maximum value of the first sub-peak is in the region of 2θ = 18.0 degrees to 19.5 degrees and the angle showing the maximum value of the second sub-peak is in the region of 2θ = 26.6 degrees to 27.5 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 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 = 27.6 degrees to 29.0 degrees.

[0052] As described above, a resin sheet is produced using a wholly aromatic polyester that contains a first structural unit having a benzene ring and a second structural unit having a naphthalene 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.

[0053] 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 = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first subpeak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second subpeak is in the range of 2θ = 26.6 degrees to 27.5 degrees, this indicates that the vicinity of the first main surface of the resin sheet has been modified by ultraviolet light.

[0054] When such a scattering spectrum is obtained, it can be said that the intermolecular repulsive force generated by the π orbital of the benzene 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.

[0055] 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 = 27.6 degrees to 29.0 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] In at least a portion of the resin sheet body within 5 μm 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 = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first sub-peak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second sub-peak is in the range of 2θ = 26.6 degrees to 27.5 degrees; and in at least a portion of the resin sheet body 5 μm or more 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 = 27.6 degrees to 29.0 degrees, 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.

[0065] 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, a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first sub-peak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second sub-peak is in the range of 2θ = 26.6 degrees to 27.5 degrees; and 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, 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 = 27.6 degrees to 29.0 degrees, 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.

[0066] The resin sheet material of the conductor layer-attached resin sheet according to the second embodiment of the present invention preferably has the following parameters in the spectrum of Fourier transform infrared spectroscopy: That is, in the spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement on the first main surface of the resin sheet using Ge as a high refractive index medium, －１ Above, 1530cm －１ The area of ​​the first peak appearing in the following region is defined as the first peak area P1, and －１ Above, 1450cm －１ The area of ​​the second peak appearing in the following region is defined as the second peak area P2, and the ratio (P1 / P2) of the first peak area P1 to the second peak area P2 is defined as the first ratio R1. In the spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement on the first main surface of the resin sheet using ZnSe as a high refractive index medium, －１ Above, 1530cm －１ The area of ​​the third peak appearing in the following region is designated as the third peak area P3, and the area of ​​the third peak appearing in the following region is designated as the third peak area P3. －１ Above, 1450cm －１When the area of ​​the fourth peak appearing in the following region is defined as a fourth peak area P4, and the ratio (P3 / P4) of the third peak area P3 to the fourth peak area P4 is defined as a second ratio R2, it is preferable that the following formulas (1) and (2) are satisfied: 0.83≦R1≦2.06 (1) 0.58≦R1 / R2≦1.09 (2)

[0067] When a conductor layer is disposed on the first main surface of a resin sheet body that satisfies the above formulas (1) and (2), the adhesion between the resin sheet and the conductor layer is improved.

[0068] The conductor layer-equipped resin sheet according to the second embodiment of the present invention can be produced by disposing a metal foil on the first main surface of the resin sheet according to the first embodiment of the present invention and then applying heat and pressure to the resin sheet. Even if such heating and pressure are applied, the spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement using the resin sheet does not change.

[0069] The Fourier transform infrared spectroscopy spectrum can be measured by the following method. First, the conductor layer of the conductor layer-attached resin sheet is removed by etching or the like. Next, the remaining resin sheet is used to measure the Fourier transform infrared spectroscopy spectrum by total reflection measurement. At this time, a high refractive index medium made of Ge and a high refractive index medium made of ZnSe are used. Then, in the obtained Fourier transform infrared spectroscopy spectrum, a peak at 1480 cm －１ Above, 1530cm －１ The area of ​​the first peak appearing in the following region is defined as the first peak area P1, and －１ Above, 1450cm －１ The area of ​​the second peak appearing in the following region is defined as a second peak area P2. Furthermore, in the spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement on the first main surface of the resin sheet using ZnSe as a high refractive index medium, －１ Above, 1530cm －１ The area of ​​the third peak appearing in the following region is designated as the third peak area P3, and the area of ​​the third peak appearing in the following region is designated as the third peak area P3. －１ Above, 1450cm －１The area of ​​the fourth peak appearing in the following region is defined as a fourth peak area P4. The first ratio R1, the second ratio R2, and R1 / R2 can be calculated from the obtained first peak area P1, second peak area P2, third peak area P3, and fourth peak area P4.

[0070] In addition, when a resin sheet with a conductor layer is part of a multilayer circuit board, the resist material or coverlay material on the board surface is removed using a solvent or mechanically to expose the conductor layer, and then the conductor layer (conductor circuit pattern) is etched away using a conventional etching solution such as an aqueous solution of ferric chloride. The resin sheet is then vacuum hot pressed to smooth out any roughness on the resin surface that had been in contact with the conductor layer, and the Fourier transform infrared spectroscopy spectrum is measured using a total reflection measurement method. The spectrum is preferably measured on the surface of the resin sheet that had been in contact with the conductor layer. The vacuum hot pressing is preferably performed with the top and bottom of the resin sheet sandwiched between the non-major surfaces of the conductor layer. The vacuum hot pressing is preferably performed at a temperature between the melting point of −50°C and −100°C, and at a pressure of 0.1 to 0.5 MPa.

[0071] 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.

[0072] 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. Note that the ten-point mean roughness (Rzjis) refers to the ten-point mean roughness defined in JIS B 0601-2001.

[0073] 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.

[0074] 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.

[0075] 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 benzene ring and a second structural unit having a naphthalene 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, and a scattering spectrum is obtained in which the angle showing the maximum value of the main peak is in the range of 2θ = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first sub-peak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second sub-peak is in the range of 2θ = 26.6 degrees to 27.5 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 = 27.6 degrees to 29.0 degrees.

[0076] 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 benzene ring and a second structural unit having a naphthalene 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 angle showing 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 = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first subpeak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second subpeak is in the range of 2θ = 26.6 degrees to 27.5 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 subpeak is in the range of 2θ = 27.6 degrees to 29.0 degrees.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] Example 1 A wholly aromatic polyester with a high HBA ratio (Tm = 330°C) was produced by melt-polymerizing a monomer ratio of p-hydroxybenzoic acid (HBA):6-hydroxy-2-naphthoic acid (HNA) = 7:3 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.

[0094] 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. ２ The temperature of the first main surface of the sheet-like material during irradiation was 103°C.

[0095] Through the above steps, a resin sheet according to Example 1 was produced.

[0096] 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.

[0097] (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.

[0098] (Comparative Example 1) A wholly aromatic polyester with a high HNA ratio (Tm = 310°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 material (thickness 50 μm) that was uniformly oriented in the in-plane direction, thereby producing a resin sheet body according to Comparative Example 1. Furthermore, a resin sheet body with a conductor layer according to Comparative Example 1 was produced in the same manner as in Example 1, except that the resin sheet body according to Comparative Example 1 was used.

[0099] (Comparative Example 2) Using a high-pressure UV treatment device, ultraviolet rays were irradiated onto the first main surface of the sheet-like material according to Comparative Example 1. At this time, the distance between the high-pressure UV tube and the sheet-like material was kept at 80 mm, and the integrated light amount of ultraviolet rays with a wavelength of 250 to 270 nm was 775 mJ / cm. ２This modified the vicinity of the first main surface of the sheet-like material. The temperature of the first main surface of the sheet-like material during irradiation was 112°C. Through the above steps, a resin sheet body according to Comparative Example 2 was produced. Furthermore, a resin sheet body with a conductor layer according to Comparative Example 2 was produced in the same manner as in Example 1, except that the resin sheet body according to Comparative Example 2 was used.

[0100] (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). To measure 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).

[0101] 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.

[0102]

[0103] As shown in Table 1, in the scattering spectra obtained using the conductor layer-attached resin sheet 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 = 20.0 to 21.0 degrees, the angle showing the maximum value of the first subpeak was in the range of 2θ = 18.0 to 19.5 degrees, and the angle showing the maximum value of the second subpeak was in the range of 2θ = 26.6 to 27.5 degrees. Furthermore, 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 = 27.6 to 29.0 degrees.

[0104] Furthermore, as shown in Table 1, in the scattering spectra obtained using the resin sheet 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 = 20.0 to 21.0 degrees, and further that there was only one sub-peak in the region of 2θ = 27.0 to 28.0 degrees.

[0105] (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.

[0106] 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.

[0107] 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.

[0108] 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, in at least a portion of the region up to 5 μm inward from 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 region of 2θ = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first sub-peak is in the region of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second sub-peak is in the region of 2θ = 26.6 degrees to 27.5 degrees, and in at least a portion of the region 5 μm or more inward from 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 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 = 27.6 degrees to 29.0 degrees, the peel strength between the conductor layer of a conductor-layer-equipped resin sheet body produced using the resin sheet body is increased.

[0109] (Measurement of the spectrum by Fourier transform infrared spectroscopy using total reflection measurement method) Two resin sheets according to Example 1 were prepared, and each resin sheet was placed in an ATR (Attenuated Total Reflection) measurement device (model name: ATRPRO610X, manufacturer: JASCO Corporation). At this time, the first main surface of each resin sheet was brought into close contact with a high refractive index medium made of Ge. Then, using a Fourier transform infrared spectrophotometer (model name: FT / IR-6X, manufacturer: JASCO Corporation), the spectra were measured at an incident angle of 45° and a measurement wavelength of 650 to 4000 cm. －１ The Fourier transform infrared spectroscopy spectrum was obtained by integrating 32 measurements within the range of 1000 nm to 1000 nm. Similarly, the Fourier transform infrared spectroscopy spectrum was obtained by using a high refractive index medium made of ZnSe.

[0110] From the spectrum of Fourier transform infrared spectroscopy when Ge is used as a high refractive index medium, －１ Above, 1530cm －１ The first peak area P1 of the first peak appearing in the following region and 1400 cm －１ Above, 1450cm －１The second peak area P2 of the second peak appearing in the following region was calculated, and the first ratio R1, which is the ratio (P1 / P2) of the first peak area P1 to the second peak area P2, was calculated. In addition, from the spectrum of Fourier transform infrared spectroscopy when ZnSe was used as the high refractive index medium, －１ Above, 1530cm －１ The third peak area P3 of the third peak appearing in the following region and 1400 cm －１ Above, 1450cm －１ The fourth peak area P4 of the fourth peak appearing in the following region was calculated, and the second ratio R2, which is the ratio (P3 / P4) of the third peak area P3 to the fourth peak area P4, was calculated. Then, the ratio (R1 / R2) of the first ratio R1 to the second ratio R2 was calculated.

[0111] The parameters of the resin sheet body according to Example 1 were as follows: The first ratio R1 (P1 / P2) was 1.350. The second ratio R2 (P3 / P4) was 1.877. R1 / R2 was 0.72.

[0112] That is, the resin sheet according to Example 1 was a resin sheet that satisfied the following formulas (1) and (2): 0.83≦R1≦2.06 (1) 0.58≦R1 / R2≦1.09 (2)

[0113] As described above, the resin sheet body with a conductor layer according to Example 1 has a high peel strength between the conductor layer and the resin sheet body. That is, it was found that when a conductor layer is disposed on the first main surface of a resin sheet body that satisfies the above formulas (1) and (2) and then heated and pressurized, the adhesive strength (peel strength) between the resin sheet body and the conductor layer is increased.

[0114] 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.

[0115] (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.

[0116]

[0117] 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.

[0118] (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 0.78 kN / m.

[0119] 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.

[0120] 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 benzene ring and a second structural unit having a naphthalene 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, in at least a portion of a region extending from the first main surface of the resin sheet to a depth of 5 μm inward, the angle showing the maximum value of the main peak is in the region of 2θ = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first sub-peak is in the region of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second sub-peak is in the region of 2θ = 26.6 degrees to 27.5 degrees; 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 = 27.6 degrees to 29.0 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 benzene ring and a second structural unit having a naphthalene 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 = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first sub-peak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second sub-peak is in the range of 2θ = 26.6 degrees to 27.5 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 = 27.6 degrees to 29.0 degrees.

3. In the spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement on the first main surface of the resin sheet using Ge as a high refractive index medium, －１ Above, 1530cm －１ The area of ​​the first peak appearing in the following region is defined as the first peak area P1, and －１ Above, 1450cm －１ The area of ​​a second peak appearing in the following region is defined as a second peak area P2, and the ratio (P1 / P2) of the first peak area P1 to the second peak area P2 is defined as a first ratio R1. In a spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement on the first main surface of the resin sheet body using ZnSe as a high refractive index medium, －１ Above, 1530cm －１ The area of ​​the third peak appearing in the following region is designated as the third peak area P3, and the area of ​​the third peak appearing in the following region is designated as the third peak area P3. －１ Above, 1450cm －１ 3. The resin sheet body according to claim 1, wherein the area of ​​a fourth peak appearing in the following region is defined as a fourth peak area P4, and the ratio (P3 / P4) of the third peak area P3 to the fourth peak area P4 is defined as a second ratio R2, and the following formulas (1) and (2) are satisfied: 0.83≦R1≦2.06 (1) 0.58≦R1 / R2≦1.09 (2) 4. A resin sheet according to any one of claims 1 to 3, wherein in the wholly aromatic polyester, the ratio of the number of moles of the first structural unit to the number of moles of the second structural unit ([number of moles of first structural unit] / [number of moles of second structural unit]) is 7 / 3 or more.

5. A resin sheet body with a conductor layer, comprising: the resin sheet body according to any one of claims 1 to 4; and a conductor layer disposed on the first main surface of the resin sheet body.

6. The resin sheet with a conductor layer according to claim 5, wherein the conductor layer is a metal foil.

7. The resin sheet with a conductor layer according to claim 6, wherein the metal foil is copper foil.

8. A resin sheet body with a conductor layer according to any one of claims 5 to 7, 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.

9. 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 benzene ring and a second structural unit having a naphthalene 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, in at least a portion of a region extending from the first main surface of the resin sheet to 5 μm inward, the angle showing the maximum value of the main peak is in the range of 2θ = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first sub-peak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second sub-peak is in the range of 2θ = 26.6 degrees to 27.5 degrees, 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 = 27.6 degrees to 29.0 degrees.

10. 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 benzene ring and a second structural unit having a naphthalene 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 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 = 20.0 degrees to 21.0 degrees, the angle showing the maximum value of the first sub-peak is in the range of 2θ = 18.0 degrees to 19.5 degrees, and the angle showing the maximum value of the second sub-peak is in the range of 2θ = 26.6 degrees to 27.5 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 = 27.6 degrees to 29.0 degrees.

11. In the spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement on the first main surface of the resin sheet using Ge as a high refractive index medium, －１ Above, 1530cm －１ The area of ​​the first peak appearing in the following region is defined as the first peak area P1, and －１ Above, 1450cm －１ The area of ​​a second peak appearing in the following region is defined as a second peak area P2, and the ratio (P1 / P2) of the first peak area P1 to the second peak area P2 is defined as a first ratio R1. In a spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement on the first main surface of the resin sheet body using ZnSe as a high refractive index medium, －１ Above, 1530cm －１ The area of ​​the third peak appearing in the following region is designated as the third peak area P3, and the area of ​​the third peak appearing in the following region is designated as the third peak area P3. －１ Above, 1450cm －１ 11. The multilayer circuit board according to claim 9 or 10, wherein when the area of ​​a fourth peak appearing in the following region is defined as a fourth peak area P4, and the ratio (P3 / P4) of the third peak area P3 to the fourth peak area P4 is defined as a second ratio R2, the following formulas (1) and (2) are satisfied: 0.83≦R1≦2.06 (1) 0.58≦R1 / R2≦1.09 (2) 12. A multilayer circuit board according to any one of claims 9 to 11, wherein in the wholly aromatic polyester, the ratio of the number of moles of the first structural unit to the number of moles of the second structural unit ([number of moles of first structural unit] / [number of moles of second structural unit]) is 7 / 3 or more.

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