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

Abstract

Provided is a resin sheet body having high adhesion to a conductor layer.　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), contains a wholly aromatic polyester, and is characterized by satisfying formulas (1) and (2) indicated below when the area of a first peak appearing in a region between 1480 cm-1 and 1530 cm-1 inclusive is defined as a first peak area P1, the area of a second peak appearing in a region between 1400 cm-1 and 1450 cm-1 inclusive 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 Fourier transform infrared spectroscopic analysis spectrum obtained by using Ge as a high-refractive-index medium to perform total reflection measurement of the first main surface (11) of the resin sheet body (10), and the area of a third peak appearing in a region between 1480 cm-1 and 1530 cm-1 inclusive is defined as a third peak area P3, the area of a fourth peak appearing in a region between 1400 cm-1 and 1450 cm-1 inclusive 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 in a Fourier transform infrared spectroscopic analysis spectrum obtained by using ZnSe as a high-refractive-index medium to perform total reflection measurement of the first main surface (11) of the resin sheet body (10).　Formula (1): 0.83 ≤ R1 ≤ 2.06. Formula (2): 0.58 ≤ R1 / R2 ≤ 1.09.

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] When manufacturing a circuit board, a conductor layer is disposed on the surface of a resin sheet body, a circuit is formed on the conductor layer by etching or the like, and resin sheets on which the circuit has been formed are laminated.

[0004] Patent Document 1 discloses a circuit board using a thermoplastic liquid crystal polymer, in which an adherend made of a thermoplastic liquid crystal polymer film and an adhesive film made of a thermoplastic liquid crystal polymer film are laminated by thermal adhesion, and in which, by X-ray photoelectron spectroscopy analysis of the adherend surface portion of the adherend film, the % ratio X (%) of the sum of the peak areas of [C-O bond] and [COO bond] to the total peak area of ​​bond peaks due to C(1s) and the % ratio Y (%) of the sum of the peak areas of [C-O bond] and [COO bond] to the total peak area of ​​bond peaks due to C(1s) for the adherend surface portion of the adhesive film satisfy the following formulas (1) and (2): 38≦X+Y≦65 (1) -8.0≦Y-X≦8.0 (2) When left standing for 60 seconds in a solder bath at 290°C according to a method in accordance with JIS-C5012, the film has solder heat resistance and the bond between the adherend film and the adhesive film is －１ The document discloses a circuit board having an adhesive strength of 1.0 to 3 kN / m in accordance with JIS G994.

[0005] Patent No. 6530716

[0006] In Patent Document 1, the adhesion between an adherend made of a thermoplastic liquid crystal polymer film and an adhesive film made of a thermoplastic liquid crystal polymer film is improved by applying a predetermined activation treatment to the adherend surface portion of the adherend film.

[0007] However, Patent Document 1 does not specifically mention the adhesion between the thermoplastic liquid crystal polymer film and a conductor layer such as copper foil placed on the surface of the thermoplastic liquid crystal polymer film, and there is room for improvement in improving the adhesion between the thermoplastic liquid crystal polymer film and the conductor layer.

[0008] 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 that has high adhesion to a conductor layer.

[0009] 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. In a 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 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 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, the following formulas (1) and (2) are satisfied: 0.83≦R1≦2.06 (1) 0.58≦R1 / R2≦1.09 (2)

[0010] 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.

[0011] 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, and the first main surface of the resin sheet body is subjected to a total reflection measurement method using Ge as a high refractive index medium, and the first main surface of the resin sheet body has 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, 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 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, the following formulas (1) and (2) are satisfied: 0.83≦R1≦2.06 (1) 0.58≦R1 / R2≦1.09 (2)

[0012] According to the present invention, it is possible to provide a resin sheet body that has high adhesion to a conductor layer.

[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. 8 is a chart of a spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement 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. In a 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 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 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, the following formulas (1) and (2) are satisfied: 0.83≦R1≦2.06 (1) 0.58≦R1 / R2≦1.09 (2) The resin sheet body according to the first embodiment of the present invention may include other configurations as long as the effects of the present invention are achieved as long as the resin sheet body has the above-described characteristics. The components of the resin sheet body 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 body 10 can be determined as appropriate, but is preferably, for example, 5 μm or more and 250 μm or less. If the thickness is 5 μm or more, sufficient strength as a substrate can be ensured. Furthermore, if the thickness is 12 μm or more, interlayer insulation can be more reliably ensured when the resin sheet body 10 is made into a multilayer circuit board. On the other hand, there is no particular upper limit to the thickness, but if the thickness is too thick, the entire electronic circuit board may become heavy, so 250 μm or less is preferable. The thickness is more preferably 12 μm or more, more preferably 150 μm or less, and even more preferably 50 μm or less.

[0020] In the resin sheet body 10, in the spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement on the first main surface of the resin sheet body using Ge as a high refractive index medium, －１ Above, 1530cm －１ The first peak appears in the following region, 1400 cm －１ Above, 1450cm －１ A second peak appears in the following region:

[0021] When total reflection measurement is performed using Ge as the high refractive index medium, a Fourier transform infrared spectroscopy spectrum is obtained in the vicinity of the first main surface of the resin sheet member 10. In this Fourier transform infrared spectroscopy spectrum, －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 due to C—H bending vibration.

[0022] In the resin sheet body 10, a first ratio R1, which is the ratio (P1 / P2) of the first peak area P1 of the first peak to the second peak area P2 of the second peak, satisfies the following formula (1). It is preferable that the first ratio R1 satisfies the following formula (1)': 0.83≦R1≦2.06 (1) 1.10≦R1≦1.70 (1)' Note that each peak area refers to the area of ​​a portion surrounded by a straight line connecting the outer tails of each peak in a spectrum obtained by Fourier transform infrared spectroscopy.

[0023] In the spectrum obtained by Fourier transform infrared spectroscopy, the smaller the first ratio R1 (i.e., the larger the second peak area P2), the more ester bonds in the wholly aromatic polyester have been converted to ketone groups. When the first ratio R1 satisfies the above formula (1), the degree to which the ester bonds have been converted to ketone groups falls within an appropriate range, making the first main surface 11 of the resin sheet 10 less susceptible to hydrolysis. Therefore, when a conductor layer is disposed on the first main surface 11 of the resin sheet 10 and heated and pressurized, the adhesive strength (peel strength) between the resin sheet 10 and the conductor layer is increased.

[0024] Furthermore, in the resin sheet body 10, in the spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement using ZnSe as a high refractive index medium, －１ Above, 1530cm －１ A third peak appears in the region below 1400 cm －１ Above, 1450cm －１ When the total reflection measurement method is performed using ZnSe as the high refractive index medium, a Fourier transform infrared spectroscopy spectrum of the deep part of the resin sheet body 10 is obtained. In this Fourier transform infrared spectroscopy spectrum, a fourth peak appears in the following region: 1480 cm －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 due to C—H bending vibration.

[0025] In the resin sheet body 10, the ratio of the first ratio R1 to the second ratio R2, which is the ratio (P3 / P4) of the third peak area P3 of the third peak to the fourth peak area P4 of the fourth peak, satisfies the following formula (2). It is preferable that the ratio of the first ratio R1 to the second ratio R2 satisfies the following formula (2)': 0.58≦R1 / R2≦1.09 (2) 0.58≦R1 / R2≦1.04 (2)' The fact that the first ratio R1 / second ratio R2 is within the above ranges means that an appropriate number of ester bonds have been transferred to ketone groups 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 and heated and pressurized, the adhesive strength (peel strength) between the resin sheet body 10 and the conductor layer is increased.

[0026] As will be described in detail later, such a resin sheet body 10 can be produced by irradiating the surface of a sheet-like material containing a wholly aromatic polyester with ultraviolet light to modify it. Therefore, if the first ratio R1 / second ratio R2 is less than 0.58, the amount of ultraviolet light irradiated is too high, which may cause deformation or a decrease in strength of the resin sheet body. Furthermore, if the first ratio R1 / second ratio R2 exceeds 1.09, the amount of ultraviolet light irradiated is too low, which may result in insufficient modification of the vicinity of the first main surface 11 of the resin sheet body 10. Therefore, the adhesive strength (peel strength) between the resin sheet body 10 and the conductor layer may be insufficient.

[0027] 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.

[0028] The resin sheet 10 contains a wholly aromatic polyester. The wholly aromatic polyester preferably 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. Note that a naphthalene ring-rich molecular structure generally reduces the fluidity of the wholly aromatic polyester, resulting in poor adhesion between the resin sheet and the conductor layer. However, the resin sheet 10 has the above-described Fourier transform infrared spectroscopy spectrum, which ensures sufficient adhesion between the resin sheet 10 and the conductor layer.

[0029] 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.

[0030] 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-GCMS. The GC / MS analyzer can be a Multi-Shot Pyrolyzer EGA / PY-3030D manufactured by Shimadzu Corporation.

[0031] 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. Furthermore, the proportion of the second structural units is preferably 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 units is within the above range, the main surface of the resin sheet is suitably modified by ultraviolet irradiation.

[0032] 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.

[0033] 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.

[0034] 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 content of 4,6-hydroxynaphthoic acid is 70% by mass or more or 20% by mass or less. 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.

[0035] 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.

[0036] <Molding step> In this step, a wholly aromatic polyester is prepared. The wholly aromatic polyester is preferably one obtained by polymerizing a monomer having a naphthalene ring and a functional group capable of forming an ester bond with a monomer having a benzene ring and a functional group capable of forming an ester bond via an ester bond. In addition, in the wholly aromatic polyester, it is preferable to blend the respective monomers so that 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.

[0037] 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.

[0038] <Ultraviolet Ray Irradiation Step> In this step, a resin sheet body is manufactured by irradiating a first main surface of a sheet-like material with ultraviolet rays and modifying the first main surface of the sheet-like material. At this time, the ultraviolet ray irradiation conditions are adjusted so that the manufactured resin sheet body has the following characteristics. 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 body 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 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 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, ultraviolet light is irradiated so as to satisfy the following formulas (1) and (2): 0.83≦R1≦2.06 (1) 0.58≦R1 / R2≦1.09 (2)

[0039] The preferred ultraviolet irradiation conditions are as follows.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] Through the above steps, the resin sheet body according to the first embodiment of the present invention can be manufactured.

[0045] 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.

[0046] As described above, the resin sheet body 10 has been modified by ultraviolet irradiation in the vicinity of the first main surface 11, making the first main surface 11 less susceptible to hydrolysis. Therefore, when a conductor layer is disposed on the first main surface 11 of the resin sheet body 10 and heated and pressurized, the adhesive strength (peel strength) between the resin sheet body 10 and the conductor layer 20 is increased.

[0047] In the conductor layer-equipped resin sheet body according to the second embodiment of the present invention, the conductor layer is preferably a metal foil. The material of the metal foil constituting the metal-clad laminate according to the present invention is not particularly limited as long as it exhibits electrical conductivity. Examples include copper, aluminum, nickel, tin, and alloys thereof. However, copper foil is preferred from the viewpoints of electrical conductivity, chemical stability, cost, etc. Furthermore, the surface of the metal foil is preferably subjected to an anti-rust treatment using Zn, Ni, Co, Cr, or the like. 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 producing the conductor layer-equipped resin sheet body according to the second embodiment of the present invention.

[0048] The heating and pressing conditions are preferably determined appropriately depending on the type of wholly aromatic polyester, 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. The heating temperature is preferably equal to or lower than the endothermic peak temperature of the wholly aromatic polyester.

[0049] Even if such heating and pressurization are performed, the spectrum of Fourier transform infrared spectroscopy obtained by performing total reflection measurement using the resin sheet body 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.

[0050] That is, the conductor layer of a certain conductor-layer-attached resin sheet body is removed by etching or the like. Next, the remaining resin sheet body is used to measure a 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 －１The area of ​​the 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 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, if the following formulas (1) and (2) are satisfied, the resin sheet body with a conductor layer can be determined to be the resin sheet body with a conductor layer according to the second embodiment of the present invention: 0.83≦R1≦2.06 (1) 0.58≦R1 / R2≦1.09 (2)

[0051] 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 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 of at least 100°C below the melting point of the resin sheet and at most 50°C below the melting point of the resin sheet, and at a pressure of 0.1 to 0.5 MPa.

[0052] In the resin sheet body with a conductor layer according to the second embodiment of the present invention, the thickness of the conductor layer may be adjusted as appropriate, for example, to about 2 μm or more and 70 μm or less. If the thickness of the conductor layer is 2 μm or more, the strength of the metal foil is sufficient, and tearing and the like can be suppressed when the conductor layer is laminated with the liquid crystal polymer film. On the other hand, if the thickness is 70 μm or less, fine wiring is sufficiently possible, and the disadvantage of the laminate or circuit board becoming too thick or heavy can be prevented. The thickness of the conductor layer is more preferably 5 μm or more and 40 μm or less.

[0053] In the conductor layer-equipped resin sheet body according to the second embodiment of the present invention, the ten-point average 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 the actual roughening height of the metal foil can be 0.4 μm or less, preferably 0.3 μm or less. A substantial roughening height of 0.4 μm or less provides good high-frequency characteristics. While the lower limit of the substantial roughening height is not particularly limited, even for a conductor layer that has not been subjected to a roughening treatment, the substantial roughening height is approximately 0.1 μm or more, and therefore the lower limit of the substantial roughening height may be 0.1 μm. The ten-point average roughness (Rzjis) refers to the ten-point average roughness defined in JIS B 0601-2001.

[0054] 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.

[0055] 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.

[0056] 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 is provided with 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, and 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 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 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 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, the following formulas (1) and (2) are satisfied: 0.83≦R1≦2.06 (1) 0.58≦R1 / R2≦1.09 (2)

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] This specification describes the following:

[0073] The present invention (1) provides a resin sheet body having a first main surface and a second main surface opposite to the first main surface, the resin sheet body containing a wholly aromatic polyester, wherein the first main surface of the resin sheet body is subjected to a total reflection measurement method using Ge as a high refractive index medium, and a Fourier transform infrared spectroscopy spectrum having a peak at 1480 cm －１ Above, 1530cm －１The 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, 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 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 The resin sheet body is characterized in that, 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)

[0074] The present invention (2) is the resin sheet according to the present invention (1), wherein the wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in the main chain.

[0075] The present invention (3) is the resin sheet according to the present invention (2), in which the proportion of the second constitutional units in the constitutional units constituting the main chain is 20% or more.

[0076] The present invention (4) is the resin sheet according to the present invention (3), in which the proportion of the second constitutional units in the constitutional units constituting the main chain is less than 50%.

[0077] The present invention (5) is the resin sheet according to any one of the present inventions (2) to (4), in which the number of moles of the first constitutional unit is greater than the number of moles of the second constitutional unit.

[0078] The present invention (6) is a resin sheet body with a conductor layer, comprising the resin sheet body according to any one of the present inventions (1) to (5) and a conductor layer disposed on a first main surface of the resin sheet body.

[0079] The present invention (7) is the resin sheet body with a conductor layer according to the present invention (6), wherein the conductor layer is a metal foil.

[0080] The present invention (8) is the resin sheet body with a conductor layer according to the present invention (7), wherein the metal foil is a copper foil.

[0081] The present invention (9) is the resin sheet body with a conductor layer according to any one of the present inventions (6) to (8), 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.

[0082] The present invention (10) 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, and the resin sheet body has a Fourier transform infrared spectroscopy spectrum obtained by performing total reflection measurement on the first main surface of the resin sheet body using Ge as a high refractive index medium, the spectrum having 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, 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 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 The multilayer circuit board is characterized in that, 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)

[0083] EXAMPLES Hereinafter, examples will be shown that more specifically disclose the resin sheet body of the present invention and the resin sheet body with a conductor layer of the present invention, but the present invention is not limited to the following examples.

[0084] 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.

[0085] 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.

[0086] Through the above steps, a resin sheet according to Example 1 was produced.

[0087] Next, an electrolytic copper foil having a thickness of 12 μm 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. Then, the resin sheet body according to Example 1 and the electrolytic copper foil were overlapped so that the first main surface of the resin sheet body according to Example 1 faced the roughened main surface of the electrolytic copper foil, and the resin sheet body according to Example 1 and the electrolytic copper foil were laminated together using a pair of roll laminators under heating and pressure of 300° C. and 3 MPa to form a laminate. In this way, a resin sheet body with a conductor layer according to Example 1 was produced.

[0088] (Examples 2) to (Examples 6) Resin sheet bodies and resin sheet bodies with conductor layers according to Examples 2 to 6 were produced in the same manner as 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.

[0089] (Example 7) 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. A resin sheet body and a resin sheet body with a conductor layer according to Example 7 were produced in the same manner as in Example 1, except that this wholly aromatic polyester was used.

[0090] 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.

[0091] (Comparative Example 2) A resin sheet body according to Comparative Example 2 was produced in the same manner as in Example 1, except that the conditions for irradiating the first main surface of the sheet-like material with ultraviolet rays were changed as shown in Table 1. Next, as in Example 1, an electrolytic copper foil was placed on the resin sheet body, and an attempt was made to bond the resin sheet body and the electrolytic copper foil together using a pair of roll laminators, but the resin sheet body broke, and a resin sheet body with a conductor layer could not be produced.

[0092]

[0093] (Measurement of the spectrum by Fourier transform infrared spectroscopy using total reflection measurement method) Two resin sheets according to each example and comparative example 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

[0049] The Fourier transform infrared spectroscopy spectrum was obtained by integrating 32 measurements within the range. Similarly, a Fourier transform infrared spectroscopy spectrum was obtained using a high refractive index medium made of ZnSe. As a representative example of a Fourier transform infrared spectroscopy spectrum, a chart obtained using the resin sheet body of Example 1 is shown in Figure 8. Figure 8 is a chart of a Fourier transform infrared spectroscopy spectrum obtained by performing total reflection measurement using the conductor layer-attached resin sheet body of Example 1. In Figure 8, the spectrum indicated by A is a spectrum measured using a high refractive index medium made of Ge. In Figure 8, the spectrum indicated by B is a spectrum measured using a high refractive index medium made of ZnSe.

[0094] 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 －１ The 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. The results are shown in Table 1.

[0095] (Measurement of Peel Strength) For the resin sheet body with a conductor layer according to each Example and Comparative Example 1, 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. Note that, since the resin sheet body with a conductor layer according to Comparative Example 2 could not be produced, the peel strength could not be measured.

[0096] 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.

[0097] (Observation of Wrinkles and Deformation) The resin sheet body with a conductor layer according to each Example and Comparative Example was visually observed to determine whether wrinkles or deformation had occurred. The evaluation criteria were as follows. The results are shown in Table 1. ⊚: No wrinkles or deformation had occurred. ◯: Slight wrinkles had occurred, but to an extent that did not pose a problem for producing a multilayer circuit board. ×: Significant deformation had occurred, and wrinkles were observed.

[0098] The resin sheet body with a conductor layer according to each Example did not have wrinkles or deformation, whereas the resin sheet body with a conductor layer according to Comparative Example 2, in which the integrated amount of ultraviolet light was large and the temperature of the first main surface of the sheet-like material was high, had a large deformation and wrinkles.

[0099] 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 body having a first main surface and a second main surface opposite to the first main surface, and containing a wholly aromatic polyester, wherein a Fourier transform infrared spectroscopy spectrum obtained by performing total reflection measurement on the first main surface of the resin sheet body using Ge as a high refractive index medium has 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 ​​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 A resin sheet body characterized in that, 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) 2. The resin sheet according to claim 1, wherein the wholly aromatic polyester contains a first structural unit having a naphthalene ring and a second structural unit having a benzene ring in the main chain.

3. The resin sheet according to claim 2, wherein the proportion of the second structural units in the structural units constituting the main chain is 20% or more.

4. The resin sheet according to claim 3, wherein the proportion of the second structural units in the structural units constituting the main chain is less than 50%.

5. A resin sheet according to any one of claims 2 to 4, wherein the number of moles of the first structural unit is greater than the number of moles of the second structural unit.

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

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

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

9. A resin sheet body with a conductor layer according to any one of claims 6 to 8, 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.

10. 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 first main surface of the resin sheet body is subjected to total reflection measurement using Ge as a high refractive index medium, and in the spectrum of Fourier transform infrared spectroscopy obtained, －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 A multilayer circuit board characterized in that, 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)

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