JP2024057908A - Resin sheet with metal foil - Google Patents

Abstract

To provide a resin sheet with metal foil or the like in which generation of swelling is suppressed, and by which a cured product having low coefficient of linear thermal expansion can be obtained.SOLUTION: A resin sheet with metal foil has a metal foil having a first face, and a resin composition layer joined to the first face of the metal foil, where a maximum height roughness (Rz) of the first face of the metal foil is 1000 nm or more; the resin composition layer contains inorganic filler (A); the content of the inorganic filler (A) is 40 mass% or more and 80 mass% or less in the case where a nonvolatile component of the resin composition layer is 100 mass%; the melt viscosity of the resin composition layer at 90°C is 5000 poise or more and 100000 poise or less; and peel strength between the metal foil and the resin composition layer is 0.01 kgf/cm or more and 0.3 kgf/cm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a resin sheet with a metal foil. Furthermore, the present invention relates to a circuit board manufactured using the resin sheet with a metal foil and a semiconductor device including the circuit board.

Circuit boards such as printed wiring boards, which are widely used in various electronic devices, are required to have thinner layers and finer wiring in order to miniaturize and improve the functionality of electronic devices. A known manufacturing technique for circuit boards is the build-up method, in which insulating layers and conductor layers (wiring layers) are stacked alternately. In the build-up method, the insulating layers are generally formed by thermally curing a resin composition layer in a resin sheet, and the conductor layers are formed by techniques such as the semi-additive process (SAP), modified semi-additive process (MSAP), and subtractive process.

In recent years, a method has been proposed for forming a conductor layer on an insulating layer by using a resin sheet with metal foil and using the metal foil as the conductor layer (see, for example, Patent Documents 1 and 2).

JP 2022-43685 A JP 2010-161497 A

A resin sheet with metal foil is usually manufactured by laminating a resin composition layer and a metal foil. This lamination is generally performed under heating conditions at atmospheric pressure, but depending on the lamination conditions or the properties of the resin composition layer, the air present at the interface between the metal foil and the resin composition layer cannot be removed, and voids may occur. If voids occur, swelling will occur between the conductor layer and the insulating layer when the resin composition layer is cured.

One possible way to suppress the occurrence of voids is to reduce the content of inorganic filler in the resin composition layer to lower the melt viscosity of the resin composition layer.

However, reducing the content of inorganic filler increases the coefficient of linear thermal expansion (CTE) of the insulating layer. If the coefficient of linear thermal expansion is high, the insulating layer will repeatedly expand and contract with temperature changes, and this distortion can cause cracks.

The present invention was devised in view of the above problems, and aims to provide a resin sheet with metal foil that suppresses the occurrence of blistering and can produce a cured product with a low linear thermal expansion coefficient; a circuit board manufactured using the resin sheet with metal foil; and a semiconductor device including the circuit board.

As a result of intensive research, the inventors discovered that it is possible to remove air from a resin sheet with metal foil, which has a metal foil having a first surface and a resin composition layer bonded to the first surface of the metal foil, by adjusting the melt viscosity at 90°C of the first surface of the metal foil and the resin composition layer, the content of inorganic filler contained in the resin composition layer, and the peel strength between the metal foil and the resin composition layer to fall within a predetermined range. This led to the discovery that it is possible to suppress swelling and obtain a cured product with a low linear thermal expansion coefficient, thereby completing the present invention.

That is, the present invention includes the following.
[1] A resin sheet with a metal foil, comprising a metal foil having a first surface and a resin composition layer bonded to the first surface of the metal foil,
The maximum height roughness (Rz) of the first surface of the metal foil is 1000 nm or more;
The resin composition layer contains (A) an inorganic filler,
(A) the content of the inorganic filler is 40% by mass or more and 80% by mass or less, when the non-volatile components of the resin composition layer are taken as 100% by mass,
The melt viscosity of the resin composition layer at 90° C. is 5,000 poise or more and 100,000 poise or less,
A resin sheet with a metal foil, wherein the peel strength between the metal foil and the resin composition layer is 0.01 kgf/cm or more and 0.3 kgf/cm or less.
[2] The resin sheet with a metal foil according to [1], having voids continuously formed at the interface between the first surface of the metal foil and the resin composition layer.
[3] The resin sheet with a metal foil according to [1] or [2], wherein the resin composition layer contains an epoxy resin (B).
[4] The resin sheet with a metal foil according to any one of [1] to [3], wherein the resin composition layer contains a curing agent (C).
[5] The resin sheet with a metal foil according to any one of [1] to [4], wherein the resin composition layer has a linear thermal expansion coefficient of 40 ppm/° C. or less after curing.
[6] The resin sheet with a metal foil according to any one of [1] to [5], which has a protective film on the side of the resin composition layer that is not bonded to the metal foil.
[7] The resin sheet with a metal foil according to [6], wherein the protective film is release-treated.
[8] The resin sheet with a metal foil according to any one of [1] to [7], wherein the metal foil is a copper foil.
[9] A circuit board comprising an insulating layer formed from a cured product of a resin composition layer of a resin sheet with a metal foil according to any one of [1] to [8], and a conductor layer formed from the metal foil of the resin sheet with a metal foil according to any one of [1] to [8].
[10] A semiconductor device comprising the circuit board according to [9].

The present invention provides a resin sheet with metal foil that is capable of suppressing the occurrence of blistering and producing a cured product with a low linear thermal expansion coefficient; a circuit board manufactured using the resin sheet with metal foil; and a semiconductor device including the circuit board.

FIG. 1 is a schematic cross-sectional view for illustrating an example of a resin sheet with a metal foil of the present invention.

The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples given below, and may be modified as desired without departing from the scope of the claims of the present invention and their equivalents.

[Resin sheet with metal foil]
The resin sheet with metal foil of the present invention has a metal foil having a first surface and a resin composition layer bonded to the first surface of the metal foil, the maximum height roughness (Rz) of the first surface of the metal foil is 1000 nm or more, the resin composition layer contains (A) an inorganic filler, the content of the (A) inorganic filler is 40 mass% or more and 80 mass% or less when the non-volatile components of the resin composition layer are 100 mass%, the melt viscosity of the resin composition layer at 90 ° C. is 5000 poise or more and 100000 poise or less, and the peel strength between the metal foil and the resin composition layer is 0.01 kgf / cm or more and 0.3 kgf / cm or less. By using such a resin sheet with metal foil, it is possible to obtain a cured product in which the occurrence of blistering is suppressed.

Figure 1 shows a schematic cross-sectional view of an example of a resin sheet with metal foil of the present invention. The resin sheet with metal foil 1 includes a metal foil 2 having a first surface 2a, and a resin composition layer 3. The resin composition layer 3 is bonded to the first surface 2a of the metal foil 2. The resin sheet with metal foil 1 may include a protective film 4 on the surface of the resin composition layer 3 that is not bonded to the metal foil 2.

Since the first surface 2a of the metal foil 2 has a maximum height roughness (Rz) of 1000 nm or more, a plurality of fine protrusions 21 are continuously formed on the entire first surface 2a. That is, countless irregularities are formed on the entire first surface 2a. In the resin sheet 1 with metal foil, the metal foil 2 and the resin composition layer 3 are bonded together so that the peel strength between the metal foil 2 and the resin composition layer 3 is 0.01 kgf/cm or more and 0.3 kgf/cm or less. When the melt viscosity of the resin composition layer 3 at 90 ° C. is 5000 poise or more and 100,000 poise or less, when the metal foil 2 and the resin composition layer 3 are bonded together so that the peel strength between the metal foil 2 and the resin composition layer 3 is 0.01 kgf/cm or more and 0.3 kgf/cm or less, the protrusions 21 on the first surface 2a are not bonded so as to be completely embedded in the resin composition layer 3, but rather a portion of the protrusions 21 is embedded in the resin composition layer 3. Therefore, at the interface between the metal foil 2 and the resin composition layer 3, there are gaps 22 formed continuously between the protrusions 21. These gaps 22 are usually formed continuously in the in-plane direction perpendicular to the thickness direction, and can be connected to the external space.

When a circuit board is formed using a resin sheet with metal foil, the resin sheet with metal foil is usually laminated by vacuum hot pressing so that the resin composition layer of the resin sheet with metal foil is bonded to the inner layer board. Conventional resin sheets with metal foil do not have a gap 22 between the metal foil 2 and the resin composition layer 3 as in the resin sheet with metal foil 1 of the present invention, so there is no escape route for voids (air) even when vacuum hot pressing is performed, and swelling occurs in the cured product of the resin composition layer. As mentioned above, in conventional resin sheets with metal foil, in order to suppress the generation of voids, it was necessary to reduce the content of inorganic filler contained in the resin composition layer and to reduce the melt viscosity of the resin composition layer. This results in a high linear thermal expansion coefficient of the insulating layer.

In contrast, the resin sheet 1 with metal foil of the present invention has voids 22, which are continuously formed between the protrusions 21. As a result, the air in the voids can be removed under the vacuum conditions of the vacuum hot press treatment, and a cured product with suppressed blistering can be obtained. In addition, since the resin sheet 1 with metal foil of the present invention has voids 22, it is not necessary to reduce the melt viscosity of the resin composition layer 3. Therefore, it is not necessary to reduce the content of inorganic filler contained in the resin composition layer, and it is also possible to further reduce the linear thermal expansion coefficient of the insulating layer. In addition, the resin sheet with metal foil of the present invention usually makes it possible to obtain a cured product of the resin composition layer having a high glass transition temperature (Tg).

The maximum height roughness (Rz) of the first surface of the metal foil is 1000 nm or more, preferably 2000 nm or more, more preferably 3000 nm or more, even more preferably 4000 nm or more, or 4500 nm or more, from the viewpoint of obtaining a cured product in which the occurrence of blistering is suppressed. The upper limit is preferably 20000 nm or less, more preferably 15000 nm or less, even more preferably 10000 nm or less, or 8000 nm or less. The maximum height roughness (Rz) can be measured by the method described in the examples below.

The resin sheet with metal foil has a peel strength between the metal foil and the resin composition layer of 0.01 kgf/cm or more, preferably 0.015 kgf/cm or more, and more preferably 0.02 kgf/cm or more, from the viewpoint of suppressing the occurrence of blistering and obtaining a cured product with a low linear thermal expansion coefficient. The upper limit is 0.3 kgf/cm or less, preferably 0.25 kgf/cm or less, and more preferably 0.2 kgf/cm or less. The peel strength can be measured by the method described in the examples below.

The melt viscosity of the resin composition layer at 90°C is 5,000 poise or more, preferably 10,000 poise or more, and more preferably 15,000 poise or more, from the viewpoint of obtaining a cured product with a low linear thermal expansion coefficient. The upper limit is 100,000 poise or less, preferably 75,000 poise or less, and more preferably 50,000 poise or less. The melt viscosity can be measured by the method described in the examples below.

<Metal foil>
The resin sheet with metal foil of the present invention has a metal foil. The conductor layer of the circuit board may be formed from the metal foil.

Examples of metal foils include copper foil and aluminum foil, with copper foil being preferred. As the copper foil, foil made of a single metal such as copper may be used, or foil made of an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

The metal foil may be a single-layer structure or a multi-layer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are laminated. Examples of multi-layer metal foils include metal foils containing a carrier metal foil and an ultra-thin metal foil bonded to the carrier metal foil. Such multi-layer metal foils may include a release layer between the carrier metal foil and the ultra-thin metal foil that enables the ultra-thin metal foil to be peeled off from the carrier metal foil. The release layer is not particularly limited as long as it can peel off the ultra-thin metal foil from the carrier metal foil, and examples of the release layer include an alloy layer of an element selected from the group consisting of Cr, Ni, Co, Fe, Mo, Ti, W, and P; an organic coating, and the like. When a multi-layer metal foil is used, the resin composition layer is provided on the ultra-thin metal foil.

From the viewpoint of obtaining a significant effect of the present invention, the thickness of the metal foil is preferably 1 μm or more, more preferably 1.5 μm or more, and even more preferably 2 μm or more. There is no particular upper limit, but it is preferably 35 μm or less, more preferably 25 μm or less, and even more preferably 15 μm or less. When the metal foil has a multi-layer structure, it is preferable that the thickness of the entire metal foil is in this range, and the thickness of the ultra-thin metal foil may be, for example, in the range of 0.1 μm to 10 μm.

The method for manufacturing the metal foil is not particularly limited as long as the specified maximum height roughness (Rz) can be obtained. The metal foil can be manufactured by known methods such as electrolysis and rolling.

The arithmetic mean roughness (Ra) of the first surface of the metal foil is preferably 300 nm or more, preferably 350 nm or more, more preferably 400 nm or more, and even more preferably 500 nm or more, from the viewpoint of improving adhesion with the resin composition layer. The upper limit is not particularly limited, but is preferably 1000 nm or less, more preferably 900 nm or less, and even more preferably 800 nm or less. The arithmetic mean roughness (Ra) is a value measured in accordance with ISO 25178, and can be measured using a non-contact surface roughness meter. An example of a non-contact surface roughness meter is the "WYKO NT3300" manufactured by Beco Instruments.

Commercially available metal foils may be used. Examples of commercially available metal foils include "Microsyn MT18Ex", "Microsyn MT18FL", "3EC-III", "3EC-M3-VLP", and "3EC-M2S-VLP" manufactured by Mitsui Mining & Smelting Co., Ltd., "JDLC", "JTCSLC", "HA-V2", "HA", and "HG" manufactured by JX Metals Mining Co., Ltd., and "CF-TX4-SV", "V9", "HD", "FLEQ HD", "FUTF", "RCF-T4X", and "RCF-T5B" manufactured by Fukuda Metal Foil & Powder Co., Ltd.

<Resin composition layer>
The resin sheet with the metal foil has a resin composition layer. The resin composition layer has a function of being thermally cured.

The components contained in the resin composition layer include (A) an inorganic filler from the viewpoint of reducing the linear thermal expansion coefficient. In addition, the resin composition layer may contain (B) an epoxy resin, (C) a curing agent, (D) a radical polymerizable compound, (E) a curing accelerator, (F) a thermoplastic resin, and (G) other additives, as necessary.

-(A) Inorganic filler-
The resin composition layer contains an inorganic filler as component (A). By using a resin composition layer containing component (A), a cured product having a low linear thermal expansion coefficient can be obtained.

(A) The inorganic filler is contained in the resin composition layer in the form of particles. An inorganic compound is used as the material for the (A) inorganic filler. Examples of the material for the (A) inorganic filler include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica is particularly suitable. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. In addition, spherical silica is preferable as the silica. (A) The inorganic filler may be used alone or in any combination of two or more types in any ratio.

(A) Commercially available inorganic fillers include, for example, "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", "YA010C", "SC2500SQ", "SO-C4", "SO-C2", and "SO-C1" manufactured by Admatechs Co., Ltd.; "UFP-30", "DAW-03", and "FB-105FD" manufactured by Denka Co., Ltd.; "Silfil NSS-3N", "Silfil NSS-4N", and "Silfil NSS-5N" manufactured by Tokuyama Corporation; "Cellfiers" and "MGH-005" manufactured by Taiheiyo Cement Corporation; and "Sfereek" and "BA-1" manufactured by JGC Catalysts and Chemicals Co., Ltd.

(A) The average particle size of the inorganic filler is not particularly limited, but is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less, even more preferably 2 μm or less, and particularly preferably 1.5 μm or less. (A) The lower limit of the average particle size of the inorganic filler is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and particularly preferably 0.2 μm or more. (A) The average particle size of the inorganic filler can be measured by a laser diffraction/scattering method based on the Mie scattering theory. Specifically, the particle size distribution of the inorganic filler is created on a volume basis using a laser diffraction/scattering particle size distribution measuring device, and the median diameter is used as the average particle size. The measurement sample can be prepared by weighing 100 mg of the inorganic filler and 10 g of methyl ethyl ketone into a vial and dispersing it by ultrasonic waves for 10 minutes. The measurement sample was measured using a laser diffraction type particle size distribution measuring device with blue and red light source wavelengths and a flow cell method to measure the volumetric particle size distribution of the inorganic filler, and the average particle size was calculated as the median diameter from the obtained particle size distribution. An example of a laser diffraction type particle size distribution measuring device is the "LA-960" manufactured by Horiba, Ltd.

The specific surface area of the (A) inorganic filler is not particularly limited, but is preferably 0.1 m ² /g or more, more preferably 0.5 m ² /g or more, even more preferably 1 m ² /g or more, and particularly preferably 3 m ² /g or more. The upper limit of the specific surface area of the (A) inorganic filler is not particularly limited, but is preferably 100 m ² /g or less, more preferably 70 m ² /g or less, even more preferably 50 m ² /g or less, even more preferably 30 m ² /g or less, and particularly preferably 10 m ² /g or less. The specific surface area of the inorganic filler is obtained by adsorbing nitrogen gas to the sample surface using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) according to the BET method, and calculating the specific surface area using the BET multipoint method.

(A) From the viewpoint of improving moisture resistance and dispersibility, it is preferable that the inorganic filler is treated with a surface treatment agent. Examples of the surface treatment agent include a fluorine-containing silane coupling agent, an aminosilane coupling agent, an epoxysilane coupling agent, a mercaptosilane coupling agent, a silane coupling agent, an alkoxysilane, an organosilazane compound, and a titanate coupling agent. In addition, the surface treatment agent may be used alone or in any combination of two or more types.

Examples of commercially available surface treatment agents include Shin-Etsu Chemical's "KBM403" (3-glycidoxypropyltrimethoxysilane), Shin-Etsu Chemical's "KBM803" (3-mercaptopropyltrimethoxysilane), Shin-Etsu Chemical's "KBE903" (3-aminopropyltriethoxysilane), Shin-Etsu Chemical's "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), Shin-Etsu Chemical's "SZ-31" (hexamethyldisilazane), Shin-Etsu Chemical's "KBM103" (phenyltrimethoxysilane), Shin-Etsu Chemical's "KBM-4803" (long-chain epoxy-type silane coupling agent), and Shin-Etsu Chemical's "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane).

From the viewpoint of improving the dispersibility of the inorganic filler, it is preferable that the degree of surface treatment with the surface treatment agent falls within a specified range. Specifically, it is preferable that 100% by mass of the inorganic filler is surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably 0.2% to 3% by mass, and even more preferably 0.3% to 2% by mass.

The degree of surface treatment by the surface treatment agent can be evaluated by the amount of carbon per unit surface area of the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of the inorganic filler is preferably 0.02 mg/m ² or more, more preferably 0.1 mg/m ² or more, and even more preferably 0.2 mg/m ² or more. On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition layer or the melt viscosity in the sheet form, it is preferably 1.0 mg/m ² or less, more preferably 0.8 mg/m ² or less, and even more preferably 0.5 mg/m ² or less.

(A) The amount of carbon per unit surface area of the inorganic filler can be measured after the surface-treated inorganic filler is washed with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler that has been surface-treated with a surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solids, the amount of carbon per unit surface area of the inorganic filler can be measured using a carbon analyzer. An example of a carbon analyzer that can be used is the "EMIA-320V" manufactured by Horiba, Ltd.

The content of (A) inorganic filler is 40% by mass or more, preferably 50% by mass or more, and more preferably 55% by mass or more, when the non-volatile components in the resin composition layer are taken as 100% by mass, from the viewpoint of obtaining a cured product with a low linear thermal expansion coefficient. The upper limit is 80% by mass or less, and preferably 75% by mass or less.

In the present invention, the content of each component in the resin composition layer is the value when the non-volatile components in the resin composition layer are taken as 100 mass %, unless otherwise specified, and the non-volatile components refer to all non-volatile components in the resin composition layer excluding the solvent.

-(B) Epoxy resin-
The resin composition layer may contain an epoxy resin (B) in combination with the component (A). The epoxy resin (B) may be used alone or in combination of two or more kinds.

(B) Examples of epoxy resins include bixylenol type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, glycidylamine type epoxy resins, glycidyl ester type epoxy resins, glycidylcyclohexane type epoxy resins, cresol novolac type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, naphthylene ether type epoxy resins, trimethylol type epoxy resins, tetraphenylethane type epoxy resins, phenolphthalimidine type epoxy resins, etc.

The resin composition layer preferably contains, as component (B), an epoxy resin having two or more epoxy groups in one molecule. From the viewpoint of obtaining the desired effect of the present invention remarkably, the ratio of the epoxy resin having two or more epoxy groups in one molecule to 100% by mass of the epoxy resin (B) is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

Epoxy resins include epoxy resins that are liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resins"). The resin composition layer may contain only liquid epoxy resins as component (B), only solid epoxy resins, or a combination of liquid and solid epoxy resins.

Preferably, the liquid epoxy resin has two or more epoxy groups in one molecule.

Preferred liquid epoxy resins are bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, glycidyl amine type epoxy resins, and epoxy resins having a butadiene structure, glycidyl cyclohexane type epoxy resins, and phenolphthalimidine type epoxy resins, with bisphenol A type epoxy resins and alicyclic epoxy resins being more preferable.

Specific examples of liquid epoxy resins include DIC's "HP4032", "HP4032D", and "HP4032SS" (naphthalene type epoxy resins); Mitsubishi Chemical's "828US", "jER828EL", "825", and "Epicoat 828EL" (bisphenol A type epoxy resins); Mitsubishi Chemical's "jER807" and "1750" (bisphenol F type epoxy resins); Mitsubishi Chemical's "jER152" (phenol novolac type epoxy resin); and Mitsubishi Chemical's "630" and "630LSD" (glycidylamine type epoxy resins). ); "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase ChemteX Corporation; "Celloxide 2021P" (alicyclic epoxy resin having an ester skeleton) manufactured by Daicel Corporation; "PB-3600" (epoxy resin having a butadiene structure) manufactured by Daicel Corporation; "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd. may be used alone or in combination of two or more types.

As the solid epoxy resin, a solid epoxy resin having two or more epoxy groups in one molecule is preferable, a solid epoxy resin having three or more epoxy groups in one molecule is more preferable, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is even more preferable.

As solid epoxy resins, bixylenol type epoxy resins, naphthalene type epoxy resins, naphthalene type tetrafunctional epoxy resins, cresol novolac type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol type epoxy resins, biphenyl type epoxy resins, naphthylene ether type epoxy resins, anthracene type epoxy resins, bisphenol A type epoxy resins, bisphenol AF type epoxy resins, and tetraphenylethane type epoxy resins are preferred, with biphenyl type epoxy resins, naphthylene ether type epoxy resins, naphthalene type epoxy resins, and bixylenol type epoxy resins being more preferred.

Specific examples of solid epoxy resins include DIC's "HP4032H" (naphthalene type epoxy resin), "HP-4700", and "HP-4710" (naphthalene type tetrafunctional epoxy resin), "N-690" (cresol novolac type epoxy resin), "N-695" (cresol novolac type epoxy resin), "HP-7200", "HP-7200HH", and "HP-7200H" (dicyclopentadiene type epoxy resin). epoxy resins), "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000", "HP6000L" (naphthylene ether type epoxy resins); "EPPN-502H" (trisphenol type epoxy resin), "NC7000L" (naphthol novolac type epoxy resin), "NC3000H", "NC3000", "NC3000L" manufactured by Nippon Kayaku Co., Ltd.; Examples of epoxy resins include "NC3100" (biphenyl type epoxy resin); "ESN475V" (naphthalene type epoxy resin) and "ESN485" (naphthol novolac type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YL6121" (biphenyl type epoxy resin), "YX4000H", "YX4000HK" (bixylenol type epoxy resin), and "YX8800" (anthracene type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100" and "CG-500" manufactured by Osaka Gas Chemical Co., Ltd.; "YL7760" (bisphenol AF type epoxy resin), "YL7800" (fluorene type epoxy resin), "jER1010" (solid bisphenol A type epoxy resin), and "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; and "WHR-991S" (phenolphthalimidine type epoxy resin) manufactured by Nippon Kayaku Co., Ltd. These may be used alone or in combination of two or more.

When a liquid epoxy resin and a solid epoxy resin are used in combination as component (B), the ratio by mass (liquid epoxy resin:solid epoxy resin) is preferably 1:0.1 to 1:20, more preferably 1:0.3 to 1:10, and particularly preferably 1:0.5 to 1:5. By keeping the ratio by mass of the liquid epoxy resin to the solid epoxy resin within this range, the desired effects of the present invention can be significantly obtained.

The epoxy equivalent of component (B) is preferably 50 g/eq. to 5000 g/eq., more preferably 50 g/eq. to 3000 g/eq., even more preferably 80 g/eq. to 2000 g/eq., and even more preferably 110 g/eq. to 1000 g/eq. Within this range, a cured product with sufficient crosslink density of the cured product of the resin composition layer can be obtained. The epoxy equivalent is the mass of an epoxy resin containing one equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

From the viewpoint of significantly achieving the desired effects of the present invention, the weight average molecular weight (Mw) of component (B) is preferably 100 to 5,000, more preferably 150 to 3,000, and even more preferably 200 to 1,500. The weight average molecular weight of the epoxy resin is the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

The content of component (B) is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on 100% by mass of the non-volatile components in the resin composition layer, from the viewpoint of obtaining a cured product exhibiting good mechanical strength and insulation reliability. The upper limit of the epoxy resin content is preferably 35% by mass or less, more preferably 30% by mass or less, and particularly preferably 25% by mass or less, from the viewpoint of significantly obtaining the desired effects of the present invention.

--(C) Curing agent--
The resin composition layer may contain a (C) curing agent in combination with the (A) component. The (C) component does not include those corresponding to the (B) component. As the (C) curing agent, a compound having a function of reacting with the (B) component to cure the resin composition layer can be used, and examples thereof include a carbodiimide-based curing agent, an active ester-based curing agent, a phenol-based curing agent, a naphthol-based curing agent, a benzoxazine-based curing agent, and a cyanate ester-based curing agent. Among them, from the viewpoint of improving the insulation reliability, it is preferable that the (C) curing agent contains one or more of a phenol-based curing agent, a naphthol-based curing agent, an active ester-based curing agent, and a cyanate ester-based curing agent. The (C) curing agent may be used alone or in combination of two or more.

As the phenol-based hardener and naphthol-based hardener, from the viewpoint of heat resistance and water resistance, a phenol-based hardener having a novolac structure or a naphthol-based hardener having a novolac structure is preferred. Also, from the viewpoint of adhesion to the conductor layer, a nitrogen-containing phenol-based hardener is preferred, and a triazine skeleton-containing phenol-based hardener is more preferred.

Specific examples of phenol-based and naphthol-based curing agents include "MEH-7700", "MEH-7810", and "MEH-7851" manufactured by Meiwa Kasei Co., Ltd., "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd., "SN170", "SN180", "SN190", "SN475", "SN485", "SN495", "SN-495V", "SN375", and "SN395" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., and "TD-2090", "LA-7052", "LA-7054", "LA-1356", "LA3018-50P", "EXB-9500", and "KA-1163" manufactured by DIC Corporation.

Specific examples of benzoxazine-based curing agents include "HFB2006M" manufactured by Showa Polymer Co., Ltd., and "P-d" and "F-a" manufactured by Shikoku Chemical Industry Co., Ltd.

Examples of cyanate ester curing agents include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanate phenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanate phenyl-1-(methylethylidene))benzene, bis(4-cyanate phenyl)thioether, and bis(4-cyanate phenyl)ether; polyfunctional cyanate resins derived from phenol novolac and cresol novolac; and prepolymers in which these cyanate resins have been partially converted to triazine. Specific examples of cyanate ester-based hardeners include Lonza Japan's "PT30" and "PT60" (phenol novolac-type multifunctional cyanate ester resins), "ULL-950S" (multifunctional cyanate ester resin), "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazine-converted into a trimer).

A carbodiimide curing agent is a compound that has one or more carbodiimide groups (-N=C=N-) in one molecule, and a carbodiimide curing agent that has two or more carbodiimide groups in one molecule is preferable.

Specific examples of carbodiimide-based curing agents include commercially available carbodiimide-based curing agents such as Carbodilite V-03 (carbodiimide group equivalent: 216, V-05 (carbodiimide group equivalent: 262), V-07 (carbodiimide group equivalent: 200), and V-09 (carbodiimide group equivalent: 200) manufactured by Nisshinbo Chemical Co., Ltd.; and Stavaxol P (carbodiimide group equivalent: 302) manufactured by Rhein Chemie.

There are no particular limitations on the active ester curing agent, but generally compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, are preferably used. The active ester curing agent is preferably one obtained by a condensation reaction between a carboxylic acid compound and/or a thiocarboxylic acid compound and a hydroxy compound and/or a thiol compound. In particular, from the viewpoint of improving heat resistance, an active ester curing agent obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester curing agent obtained from a carboxylic acid compound and a phenol compound and/or a naphthol compound is more preferred. Examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol S, phenolphthaline, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, and phenol novolak. Here, "dicyclopentadiene-type diphenol compounds" refer to diphenol compounds obtained by condensing one molecule of dicyclopentadiene with two molecules of phenol.

Specifically, active ester compounds containing a dicyclopentadiene-type diphenol structure, active ester compounds containing a naphthalene structure, active ester compounds containing an acetylated product of phenol novolac, and active ester compounds containing a benzoylated product of phenol novolac are preferred, and among these, active ester compounds containing a naphthalene structure and active ester compounds containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

Commercially available active ester curing agents include active ester compounds containing a dicyclopentadiene-type diphenol structure such as "EXB-9451", "EXB-9460", "EXB-9460S", "HPC-8000-65T", "HPC-8000H-65TM", and "HPC-8000L-65TM" (manufactured by DIC Corporation), active ester compounds containing a naphthalene structure such as "EXB-9416-70BK", "EXB-8100L-65T", "EXB-8150-65T", "EXB-8150L-65T", "HPC-8150-60T", "HPC-8150-62T", and "HP-B-8151-62T" (manufactured by DIC Corporation), and phenol novolac Examples of active ester compounds containing acetylated compounds include "DC808" (manufactured by Mitsubishi Chemical Corporation), active ester compounds containing benzoylated phenol novolac include "YLH1026" (manufactured by Mitsubishi Chemical Corporation), active ester curing agents that are acetylated phenol novolac include "DC808" (manufactured by Mitsubishi Chemical Corporation), active ester curing agents that are benzoylated phenol novolac include "YLH1026" (manufactured by Mitsubishi Chemical Corporation), "YLH1030" (manufactured by Mitsubishi Chemical Corporation), and "YLH1048" (manufactured by Mitsubishi Chemical Corporation), and an active ester compound containing a styryl group includes "PC1300-02-65MA" (manufactured by Air Water Corporation).

The ratio of the amount of the epoxy resin (B) to the component (C) is preferably in the range of 1:0.01 to 1:5, more preferably 1:0.3 to 1:3, and even more preferably 1:0.5 to 1:2, in terms of the ratio of [total number of epoxy groups in the epoxy resin (B)] to [total number of active groups in the component (C)]. Here, the "number of epoxy groups in the epoxy resin" refers to the total value obtained by dividing the mass of the non-volatile components of the epoxy resin present in the resin composition layer by the epoxy equivalent. The "number of active groups in the component (C)" refers to the total value obtained by dividing the mass of the non-volatile components of the component (C) present in the resin composition layer by the active group equivalent. By setting the ratio of the epoxy resin to the component (C) within this range, the effects of the present invention can be obtained significantly.

From the viewpoint of obtaining the desired effect of the present invention remarkably, the content of the (C) component is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, assuming that the non-volatile components in the resin composition layer are 100% by mass. The upper limit is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less.

-(D) Radical polymerizable resin-
The resin composition layer may contain a radical polymerizable resin (D) in combination with the component (A). The radical polymerizable resin (D) as the component (D) does not include those corresponding to the above-mentioned components (B) to (C).

The type of radical polymerizable resin is not particularly limited as long as it has one or more (preferably two or more) radical polymerizable unsaturated groups in one molecule. Examples of the radical polymerizable resin include resins having one or more radical polymerizable unsaturated groups selected from maleimide groups, vinyl groups, allyl groups, styryl groups, vinylphenyl groups, acryloyl groups, methacryloyl groups, fumaroyl groups, and maleoyl groups. Among these, from the viewpoint of obtaining the effects of the present invention significantly, the radical polymerizable resin is preferably one or more selected from maleimide resins, (meth)acrylic resins, and styryl resins, and more preferably maleimide resins.

There is no particular limitation on the type of maleimide resin, so long as it has one or more (preferably two or more) maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl groups) in one molecule. Examples of maleimide resins include (1) maleimide resins containing an aliphatic skeleton (preferably an aliphatic skeleton having 36 carbon atoms derived from dimer diamine), such as "BMI-3000J", "BMI-5000", "BMI-1400", "BMI-1500", "BMI-1700", and "BMI-689" (all manufactured by DigiCner Molecules), and "SLK6895-T90" (manufactured by Shin-Etsu Chemical Co., Ltd.); (2) maleimide resins containing an indane skeleton, as described in the Japan Institute of Invention and Innovation Disclosure Technical Bulletin No. 2020-500211; and (3) maleimide resins containing an aromatic ring skeleton directly bonded to the nitrogen atom of the maleimide group, such as "MIR-3000-70MT" (manufactured by Nippon Kayaku Co., Ltd.), "BMI-4000" (manufactured by Daiwa Kasei Co., Ltd.), and "BMI-80" (manufactured by Keiai Kasei Co., Ltd.).

The (meth)acrylic resin may be a monomer or an oligomer, and is not particularly limited in type, so long as it has one or more (preferably two or more) (meth)acryloyl groups in one molecule. Here, the term "(meth)acryloyl group" is a general term for acryloyl and methacryloyl groups. Examples of methacrylic resins include (meth)acrylate monomers, as well as (meth)acrylic resins such as "A-DOG" (manufactured by Shin-Nakamura Chemical Co., Ltd.), "DCP-A" (manufactured by Kyoeisha Chemical Co., Ltd.), "NPDGA", "FM-400", "R-687", "THE-330", "PET-30", and "DPHA" (all manufactured by Nippon Kayaku Co., Ltd.).

The type of styryl resin is not particularly limited, and may be a monomer or oligomer, as long as it has one or more (preferably two or more) styryl groups or vinylphenyl groups in one molecule. Examples of styryl resins include styrene monomers, as well as styryl resins such as "OPE-2St", "OPE-2St 1200", and "OPE-2St 2200" (all manufactured by Mitsubishi Gas Chemical Co., Ltd.).

From the viewpoint of obtaining a significant effect of the present invention, the content of component (D) is preferably 1% by mass or more, more preferably 3% by mass or more, more preferably 5% by mass or more, and is preferably 15% by mass or less, more preferably 13% by mass or less, and even more preferably 10% by mass or less, assuming that the non-volatile components in the resin composition layer are 100% by mass.

-(E) Curing accelerator-
The resin composition layer may contain a curing accelerator (E) in combination with the component (A). The curing accelerator (E) as the component (E) does not include those corresponding to the above-mentioned components (B) to (D). The curing accelerator (E) functions as a curing catalyst that accelerates the curing of the epoxy resin (B).

As the (E) curing accelerator, a compound that accelerates the curing of the epoxy resin can be used. Examples of such (E) curing accelerators include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, and amine-based curing accelerators. As the (E) curing accelerator, one type may be used alone, or two or more types may be used in combination.

Examples of phosphorus-based curing accelerators include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium)pyromellitate, tetrabutylphosphonium hydrogenhexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butyldimethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphine aromatic phosphonium salts such as sulfonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-quinone addition products such as triphenylphosphine-p-benzoquinone addition products; tributylphosphine, tri-t Aliphatic phosphines such as tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine; dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, ) phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, 2,2'-bis(diphenylphosphino)diphenyl ether and other aromatic phosphines.

Examples of urea-based hardening accelerators include 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. aromatic dimethylureas such as 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea) [toluene bisdimethylurea], etc.

Examples of guanidine-based curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide.

Examples of imidazole-based curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2- Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl -(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct , 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, and other imidazole compounds and adducts of imidazole compounds and epoxy resins. Commercially available imidazole curing accelerators include, for example, "1B2PZ", "2E4MZ", "2MZA-PW", "2MZ-OK", "2MA-OK", "2MA-OK-PW", "2PHZ", "2PHZ-PW", "Cl1Z", "Cl1Z-CN", "Cl1Z-CNS", and "C11Z-A" manufactured by Shikoku Chemical Industry Co., Ltd.; and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

Metal-based curing accelerators include, for example, organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organocobalt complexes such as cobalt (II) acetylacetonate and cobalt (III) acetylacetonate, organocopper complexes such as copper (II) acetylacetonate, organozinc complexes such as zinc (II) acetylacetonate, organoiron complexes such as iron (III) acetylacetonate, organonickel complexes such as nickel (II) acetylacetonate, and organomanganese complexes such as manganese (II) acetylacetonate. Organometallic salts include, for example, zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

Examples of amine-based curing accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene. Commercially available amine-based curing accelerators may be used, such as "MY-25" manufactured by Ajinomoto Fine-Techno Co., Ltd.

From the viewpoint of obtaining a significant effect of the present invention, the content of the curing accelerator (E) is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and even more preferably 0.05% by mass or more, and is preferably 1.5% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less, when the non-volatile components in the resin composition layer are taken as 100% by mass.

-(F) Thermoplastic resin-
The resin composition layer may contain a thermoplastic resin (F) in combination with the component (A). The thermoplastic resin (F) as the component (F) does not include those corresponding to the above-mentioned components (B) to (E).

(F) Examples of the thermoplastic resin include phenoxy resin, polyimide resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polycarbonate resin, polyetheretherketone resin, polyester resin, etc. (F) Thermoplastic resin may be used alone or in combination of two or more types.

Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenolacetophenone skeleton, novolac skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton, and trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both phenoxy resins containing a bisphenol A skeleton); "YX8100" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol S skeleton); "YX6954" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol acetophenone skeleton); "FX280" and "FX293" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.; "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290", "YL7482" and "YL7891BH30" manufactured by Mitsubishi Chemical Corporation; and the like.

Specific examples of polyimide resins include "SLK-6100" manufactured by Shin-Etsu Chemical Co., Ltd., and "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd.

Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, with polyvinyl butyral resins being preferred. Specific examples of polyvinyl acetal resins include Denka Butyral 4000-2, Denka Butyral 5000-A, Denka Butyral 6000-C, and Denka Butyral 6000-EP manufactured by Denki Kagaku Kogyo Co., Ltd.; and S-LEC BH series, BX series (e.g. BX-5Z), KS series (e.g. KS-1), BL series, and BM series manufactured by Sekisui Chemical Co., Ltd.

Examples of polyolefin resins include ethylene-based copolymer resins such as low-density polyethylene, very low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; polyolefin-based polymers such as polypropylene and ethylene-propylene block copolymer.

Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxyl group-containing polybutadiene resins, phenolic hydroxyl group-containing polybutadiene resins, carboxyl group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, polyphenylene ether-polybutadiene resins, etc.

Specific examples of polyamide-imide resins include "Viromax HR11NN" and "Viromax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins include modified polyamide-imides such as "KS9100" and "KS9300" (polyamide-imide containing a polysiloxane skeleton) manufactured by Hitachi Chemical Co., Ltd.

An example of a polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

A specific example of a polyphenylene ether resin is NORYL SA90 manufactured by SABIC. A specific example of a polyetherimide resin is ULTEM manufactured by GE.

Examples of polycarbonate resins include hydroxyl group-containing carbonate resins, phenolic hydroxyl group-containing carbonate resins, carboxyl group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, and urethane group-containing carbonate resins. Specific examples of polycarbonate resins include "FPC0220" manufactured by Mitsubishi Gas Chemical Co., Ltd., "T6002" and "T6001" (polycarbonate diols) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090", "C-2090", and "C-3090" (polycarbonate diols) manufactured by Kuraray Co., Ltd. Specific examples of polyether ether ketone resins include "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd.

Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polytrimethylene terephthalate resin, polytrimethylene naphthalate resin, and polycyclohexane dimethyl terephthalate resin.

The weight average molecular weight (Mw) of the (F) thermoplastic resin is preferably greater than 5,000, more preferably 8,000 or more, even more preferably 10,000 or more, and particularly preferably 20,000 or more, and is preferably 100,000 or less, more preferably 70,000 or less, even more preferably 60,000 or less, and particularly preferably 50,000 or less.

From the viewpoint of obtaining a significant effect of the present invention, the content of the thermoplastic resin (F) is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more, based on 100% by mass of the non-volatile components in the resin composition layer, and is preferably 5% by mass or less, more preferably 3% by mass or less, and particularly preferably 1.5% by mass or less.

- (G) Other additives -
The resin composition layer may further contain (G) other additives as an optional non-volatile component in combination with the (A) component. (G) optional additives include, for example, organic fillers; polymerization initiators; organic metal compounds such as organic copper compounds, organic zinc compounds, and organic cobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone leveling agents and acrylic polymer leveling agents; thickeners such as bentone and montmorillonite; defoamers such as silicone defoamers, acrylic defoamers, fluorine defoamers, and vinyl resin defoamers; ultraviolet absorbers such as benzotriazole ultraviolet absorbers; adhesion improvers such as urea silane; adhesion imparters such as triazole adhesion imparters, tetrazole adhesion imparters, and triazine adhesion imparters; hindered phenol acids. Examples of the additives include antioxidants such as oxidation inhibitors, fluorescent brighteners such as stilbene derivatives, surfactants such as fluorine-based surfactants and silicone-based surfactants, flame retardants such as phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, phosphinic acid compounds, red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic flame retardants (e.g., antimony trioxide), and dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants, stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic anhydride-based stabilizers, photopolymerization initiators such as tertiary amines, and photosensitizers such as pyrarizones, anthracenes, coumarins, xanthones, and thioxanthones. (G) The optional additives may be used alone or in combination of two or more.

The resin composition layer may contain a solvent as a volatile component. From the viewpoint of adjusting the melt viscosity of the resin composition layer at 90°C, it is preferable that the amount of solvent such as an organic solvent in the resin composition layer is small. The amount of solvent in the resin composition layer (residual solvent amount) is preferably 5 mass% or less, more preferably 3 mass% or less, even more preferably 2 mass% or less, even more preferably 1.5 mass% or less, and particularly preferably 1 mass% or less. There is no particular lower limit, but it may be 0.0001 mass% or more.

Examples of solvents include ketones such as methyl ethyl ketone (MEK) and cyclohexanone, aromatic hydrocarbons such as xylene and tetramethylbenzene, glycol ethers such as methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether, esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, carbitol acetate, and ethyl diglycol acetate, aliphatic hydrocarbons such as octane and decane, and petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. These may be used alone or in combination of two or more.

The thickness of the resin composition layer is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 55 μm or less, from the viewpoint of making the printed wiring board thinner and being able to provide a cured product with excellent insulation even if the cured product of the resin composition layer is a thin film. The lower limit of the thickness of the resin composition layer is not particularly limited, but can usually be 5 μm or more, 10 μm or more, etc.

<Protective film>
The resin sheet with metal foil may further include a protective film as necessary. The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film, it is possible to suppress adhesion of dirt and the like to the surface of the resin composition layer and scratches.

Examples of protective films include films made of plastic materials, metal foils, and release paper, with films made of plastic materials and metal foils being preferred. The surface of the protective film that is to be bonded to the resin composition layer may be subjected to a matte treatment, corona treatment, or antistatic treatment.

<Method of manufacturing resin sheet with metal foil>
The method for producing a resin sheet with metal foil is, for example, to prepare a resin varnish by dissolving the components contained in the resin composition layer in a solvent, and then to apply the resin varnish to a protective film using a die coater or the like, and then to dry the resin composition layer on the protective film. Then, a metal foil is laminated to the surface of the resin composition layer using a roll laminator or the like, thereby producing a resin sheet with metal foil. The solvent may be one described above.

Drying may be performed by known methods such as heating or blowing hot air. There are no particular limitations on the drying conditions, but drying is performed so that the content of organic solvent in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. Although it varies depending on the boiling point of the solvent in the resin varnish, for example, when using a resin varnish containing 30% by mass to 60% by mass of solvent, the resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

The resin sheet with metal foil can be stored in a roll. If the resin sheet with metal foil has a protective film, it can be used by peeling off the protective film.

<Physical properties of resin sheet with metal foil>
The resin sheet with metal foil is heated at 100°C for 30 minutes and then at 190°C for 120 minutes using a vacuum hot press machine to harden the resin composition layer, and the resin sheet with metal foil exhibits the characteristic that no abnormality such as blister is observed between the metal foil and the cured product. That is, an insulating layer is obtained in which blister occurring between the conductor layer and the insulating layer is suppressed. Even when the resin sheet with metal foil is heated at 100°C for 30 minutes and then at 190°C for 120 minutes, no abnormality such as blister is observed in the small pieces of the insulating layer. The evaluation of blister can be measured by the method described in the examples below.

The resin sheet with metal foil of the present invention contains an inorganic filler in the resin composition layer, and the content of the inorganic filler is 40% by mass or more and 80% by mass or less, assuming that the non-volatile components of the resin composition layer are 100% by mass. Therefore, the cured product of the resin composition layer exhibits the characteristic of having a low linear thermal expansion coefficient (CTE). Therefore, the cured product provides an insulating layer with a low linear thermal expansion coefficient. The linear thermal expansion coefficient is preferably 40 ppm/°C or less, more preferably 35 ppm/°C or less, and more preferably 30 ppm/°C or less. The lower limit is not particularly limited, but may be 1 ppm/°C or more. The linear thermal expansion coefficient can be measured according to the method described in the examples below.

The resin sheet with metal foil of the present invention contains an inorganic filler in the resin composition layer, and the content of the inorganic filler is 40% by mass or more and 80% by mass or less when the non-volatile components of the resin composition layer are taken as 100% by mass. Therefore, the resin composition layer is usually cured using a vacuum hot press machine, and the cured product has a high glass transition temperature (Tg). Thus, an insulating layer with a high glass transition temperature is obtained. The glass transition temperature of the cured product of the resin composition layer is preferably 140°C or more, more preferably 145°C or more, and even more preferably 150°C or more. The upper limit is not particularly limited, but may be, for example, 300°C or less. The glass transition temperature (Tg) can be measured by the method described in the examples below.

The first surface of the metal foil of the resin sheet with metal foil of the present invention has a maximum height roughness (Rz) of 1000 nm or more, so that protrusions are continuously formed on the first surface. In the resin sheet with metal foil of the present invention, the metal foil and the resin composition layer are bonded so that the peel strength between the metal foil and the resin composition layer is 0.01 kgf/cm or more and 0.3 kgf/cm or less, so that some of the protrusions continuously formed on the first surface are embedded in the resin composition layer. Therefore, the interface between the metal foil and the resin composition layer has voids continuously formed between the protrusions. When the resin sheet with metal foil is immersed in water, the water penetrates into the voids in the resin sheet with metal foil. The voids where the water penetrates change color. Therefore, when the discolored areas spread throughout the resin sheet with metal foil, it can be evaluated that the voids are continuous. When the resin sheet with metal foil of the present invention is immersed in water, the entire resin sheet with metal foil changes color. Therefore, the resin sheet with metal foil of the present invention has voids continuously formed. The continuity of voids is evaluated using the method described in the Examples below.

By using the resin sheet with metal foil of the present invention, the occurrence of blistering is suppressed, and an insulating layer with a low linear thermal expansion coefficient can be obtained. Therefore, the resin sheet with metal foil of the present invention can be suitably used as a resin sheet for forming both an insulating layer and a conductor layer (for forming an insulating layer and a conductor layer) in the manufacture of a circuit board, can be suitably used as a resin sheet for forming both an insulating layer and a conductor layer using a vacuum hot press process in the manufacture of a circuit board (for forming an insulating layer and a conductor layer using a vacuum hot press process), can be suitably used as a resin sheet for forming both an insulating layer and a conductor layer (for forming an insulating layer and a conductor layer) in the manufacture of a printed wiring board, and can be suitably used as a resin sheet for forming both an insulating layer and a conductor layer using a vacuum hot press process in the manufacture of a printed wiring board (for forming an insulating layer and a conductor layer using a vacuum hot press process).

[Circuit board]
The circuit board of the present invention can be produced by using the resin sheet with a metal foil of the present invention. That is, it is possible to provide a circuit board including an insulating layer made of a cured product of the resin composition layer of the resin sheet with a metal foil of the present invention, and a conductor layer formed from a metal foil.

One embodiment of the circuit board is a printed wiring board. The printed wiring board includes an insulating layer made of a cured resin composition layer of the resin sheet with metal foil of the present invention, and a conductor layer formed from metal foil.

The printed wiring board can be produced, for example, by using the above-mentioned resin sheet with metal foil, by a method including the following steps (I) and (II).
(I) A step of laminating a resin composition layer in a resin sheet with a metal foil on an inner layer substrate by a vacuum hot press process; (II) A step of thermally curing the resin composition layer to form an insulating layer.

The "inner layer substrate" used in step (I) is a member that will be the substrate of the printed wiring board, and examples thereof include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The substrate may have a conductor layer on one or both sides, and the conductor layer may be patterned. An inner layer substrate having a conductor layer (circuit) formed on one or both sides of the substrate may be called an "inner layer circuit substrate." In addition, intermediate products on which an insulating layer and/or a conductor layer is to be formed during the manufacture of a printed wiring board are also included in the "inner layer substrate" of the present invention. When the printed wiring board is a circuit board with built-in components, an inner layer substrate with built-in components may be used.

The inner layer substrate and the resin sheet with metal foil are laminated by vacuum hot pressing so that the resin composition layer of the resin sheet with metal foil is bonded to the inner layer substrate.

First, the inner layer substrate and the resin sheet with metal foil are set in a vacuum hot press device so that the resin composition layer of the resin sheet with metal foil is bonded to the inner layer substrate. Next, a vacuum hot press process is performed to heat and press the inner layer substrate and the resin composition layer under reduced pressure conditions.

The inner layer substrate and the resin sheet with metal foil may be set in a vacuum hot press device via cushion paper, a metal plate such as a stainless steel plate (SUS plate), a release film, etc.

The vacuum hot press process can be carried out using a conventional vacuum hot press device that presses the inner layer substrate and the resin sheet with metal foil from both sides with a heated metal plate such as a stainless steel plate. An example of a commercially available vacuum hot press device is the "VH1-1603" manufactured by Kitagawa Seiki Co., Ltd.

The vacuum hot pressing process may be performed only once, or may be repeated two or more times. When performing the process two or more times, the pressure, heating temperature, pressing time, etc. may be the same or different.

In the vacuum hot press treatment, the compression pressure (pressing force) is preferably 5 kgf/ ^cm2 or more, more preferably 10 kgf/ ^cm2 or more, even more preferably 15 kgf/ ^cm2 or more, and is preferably 50 kgf/ ^cm2 or less, more preferably 35 kgf/ ^cm2 or less, even more preferably 25 kgf/ ^cm2 or less.

In the vacuum hot press treatment, the atmospheric pressure, i.e., the pressure (degree of vacuum) during decompression in the chamber in which the laminate structure to be treated is stored, is preferably 3× ¹⁰ MPa or less, more preferably 1× ¹⁰ MPa or less. There is no particular lower limit, but it may be 1× ¹⁰ MPa or more.

In the vacuum hot press treatment, the heating temperature varies depending on the composition of the resin composition layer, but is preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher. The upper limit of the heating temperature is not particularly limited, but can usually be 300°C or lower. The resin composition layer may be thermally cured by heating in the vacuum hot press treatment to form an insulating layer.

In the vacuum hot press treatment, the pressing time is preferably 5 minutes or more, more preferably 10 minutes or more, and even more preferably 15 minutes or more. There is no particular upper limit, but it is preferably 300 minutes or less, more preferably 200 minutes or less, and even more preferably 150 minutes or less.

In the lamination process using vacuum hot pressing, when the pressure inside the chamber is reduced, air is expelled from the voids between the metal foil and the resin composition layer through the gap. After the air is expelled from the voids, the inner layer substrate and the resin composition layer are bonded together by pressing, and at the same time, the resin composition layer and the metal foil are bonded together. Since pressing is performed after the air is expelled from the voids as described above, swelling can be suppressed.

After laminating a resin sheet with a metal foil on the inner layer substrate by vacuum pressing, in step (II), the resin composition layer is thermally cured to form an insulating layer. For example, when performing pressing by vacuum hot pressing, a method of thermally curing the resin composition layer by using the heat generated during pressing to form an insulating layer can be used as a method of thermally curing the resin composition layer to form an insulating layer.

The thermal curing conditions for the resin composition layer are not particularly limited, and conditions normally used for forming an insulating layer for a printed wiring board may be used.

For example, the thermal curing conditions for the resin composition layer vary depending on the type of resin composition layer, but the curing temperature is preferably 120°C to 240°C, more preferably 150°C to 220°C, and even more preferably 170°C to 210°C. The curing time is preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

Before the resin composition layer is thermally cured, the resin composition layer may be preheated at a temperature lower than the curing temperature. For example, prior to thermally curing the resin composition layer, the resin composition layer may be preheated for 5 minutes or more (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes) at a temperature of 50°C or more and less than 120°C (preferably 60°C or more and 115°C or less, and more preferably 70°C or more and 110°C or less).

The resin sheet with metal foil used in the present invention contains metal foil, so step (III) may include a step of forming a conductor layer (circuit) by a subtractive method or a modified semi-additive method.

In step (III), the metal foil in the resin sheet with metal foil can be used to form a conductor layer by a subtractive method or a modified semi-additive method.

In the subtractive method, unnecessary parts of the metal foil (non-circuit forming parts) are selectively removed by etching or the like to form a circuit. The circuit formation by the subtractive method may be performed according to a known procedure. For example, the circuit formation by the subtractive method can be performed by a method including: i) providing an etching resist on the surface of the metal foil (i.e., the surface opposite to the surface bonded to the resin composition layer); ii) exposing and developing the etching resist to form a wiring pattern; iii) etching and removing the exposed metal foil parts; and iv) removing the etching resist.

In the modified semi-additive method, the non-circuit forming portion of the metal foil is protected by a plating resist, a metal such as copper is thickly applied to the circuit forming portion by electrolytic plating, the plating resist is removed, and the metal foil other than the circuit forming portion is removed by etching to form a circuit. The circuit formation by the modified semi-additive method may be carried out according to a known procedure. For example, the circuit formation by the modified semi-additive method may be carried out by a method including: i) providing a plating resist on the surface of the metal foil (i.e., the surface opposite to the surface bonded to the resin composition layer), ii) exposing and developing the plating resist to form a wiring pattern, iii) electrolytic plating through the plating resist, iv) removing the plating resist, and v) etching and removing the metal foil other than the circuit forming portion. In addition, if the metal foil is thick, the entire metal foil may be thinned by etching or the like before the above i) so that the metal foil has a desired thickness (usually 5 μm or less, 4 μm or less, or 3 μm or less).

When manufacturing a printed wiring board, a step (IV) of drilling holes and a step (V) of roughening the insulating layer may be further carried out. These steps (IV) to (V) may be carried out according to various methods known to those skilled in the art and used in the manufacture of printed wiring boards. Furthermore, if necessary, the formation of the insulating layer and the conductor layer in steps (I) to (V) may be repeated to form a multilayer wiring board.

[Semiconductor device]
The semiconductor device of the present invention includes the circuit board or printed wiring board of the present invention. The semiconductor device of the present invention can be manufactured using the circuit board or printed wiring board of the present invention.

Semiconductor devices include various semiconductor devices used in electrical appliances (e.g., computers, mobile phones, digital cameras, and televisions) and vehicles (e.g., motorcycles, automobiles, trains, ships, and aircraft).

The semiconductor device of the present invention can be manufactured by mounting a component (semiconductor chip) on a conductive portion of a printed wiring board. A "conductive portion" is a portion of a printed wiring board that transmits an electrical signal, and the portion may be either on the surface or embedded. There are no particular limitations on the semiconductor chip, so long as it is an electrical circuit element made of semiconductor material.

The method of mounting semiconductor chips when manufacturing semiconductor devices is not particularly limited as long as the semiconductor chip functions effectively, but specific examples include wire bonding mounting, flip chip mounting, bumpless buildup layer (BBUL) mounting, anisotropic conductive film (ACF) mounting, non-conductive film (NCF) mounting, etc. Here, "bumpless buildup layer (BBUL) mounting" refers to "a mounting method in which a semiconductor chip is directly embedded in a recess in a printed wiring board and the semiconductor chip is connected to the wiring on the printed wiring board."

The present invention will be specifically described below with reference to examples. The present invention is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

Formulation Example 1: Preparation of resin varnish 1 20 parts of bisphenol A type epoxy resin ("828EL" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent of about 180 g/eq.) and 20 parts of biphenyl type epoxy resin ("NC3000L" manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent of about 269 g/eq.) were added to 40 parts of methyl ethyl ketone (MEK), and dissolved by heating with stirring. This was cooled to room temperature to prepare an epoxy resin dissolved composition. To this epoxy resin solution, 10 parts of a triazine skeleton-containing phenolic curing agent (DIC Corporation's "LA-3018-50P", active group equivalent of about 151 g/eq., 2-methoxypropanol solution with a non-volatile content of 50%), 50 parts of an active ester compound (DIC Corporation's "HPC-8000-65T", active ester group equivalent of about 223 g/eq., toluene solution with a non-volatile content of 65%), and 10 parts of a silane coupling agent (Shin-Etsu Chemical Co., Ltd.'s "KBM-573" were added. Resin varnish 1 was prepared by mixing 180 parts of spherical silica surface-treated with silica gel ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm), 4 parts of an amine-based curing accelerator (4-dimethylaminopyridine (DMAP), MEK solution with 5 mass % solids), and 5 parts of an imidazole-based curing accelerator ("1B2PZ" manufactured by Shikoku Kasei Co., Ltd., 1-benzyl-2-phenylimidazole, MEK solution with 10 mass % solids), and dispersing the mixture uniformly using a high-speed rotating mixer.

Formulation Example 2: Preparation of Resin Varnish 2 10 parts of bisphenol A type epoxy resin ("828EL" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent of about 180 g/eq.), 20 parts of biphenyl type epoxy resin ("NC3000L" manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent of about 269 g/eq.), and 10 parts of naphthylene ether type epoxy resin ("HP-6000" manufactured by DIC Corporation, epoxy equivalent of about 250 g/eq.) were added to 20 parts of methyl ethyl ketone (MEK), and dissolved by heating with stirring. This was cooled to room temperature to prepare an epoxy resin dissolved composition. To this epoxy resin solution, 15 parts of a triazine skeleton-containing phenolic curing agent (DIC Corporation's "LA-7054", active group equivalent of about 125 g/eq., MEK solution with non-volatile content of 60%), 10 parts of a naphthol-type curing agent (Nippon Steel Chemical & Material Corporation's "SN-485", hydroxyl group equivalent of about 205 g/eq.), and 10 parts of a phenoxy resin (Mitsubishi Chemical Corporation's "YX7553BH30", MEK and cyclohexanone with non-volatile content of 30% by mass) were added. Resin varnish 2 was prepared by mixing 8 parts of a 1:1 solution of silane, 100 parts of spherical silica ("SO-C2" manufactured by Admatechs, average particle size 0.5 μm) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.), and 5 parts of an imidazole curing accelerator ("1B2PZ" manufactured by Shikoku Kasei Co., Ltd., 1-benzyl-2-phenylimidazole, MEK solution with 10 mass % solids content) and uniformly dispersing the mixture in a high-speed rotary mixer.

Formulation Example 3: Preparation of Resin Varnish 3 15 parts of bisphenol A type epoxy resin ("828EL" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent of about 180 g/eq.), 10 parts of naphthalene type epoxy resin ("ESN475V" manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent of about 332 g/eq.), and 10 parts of naphthylene ether type epoxy resin ("HP-6000" manufactured by DIC, epoxy equivalent of about 250 g/eq.) were added with 40 parts of methyl ethyl ketone (MEK) and dissolved by heating with stirring. This was cooled to room temperature to prepare an epoxy resin dissolved composition. To this dissolved composition, 30 parts of an active ester compound (DIC Corporation's "HPC-8000-65T", active ester group equivalent of about 223 g/eq., toluene solution with non-volatile content of 65%), 20 parts of a prepolymer of bisphenol A dicyanate (Lonza Japan's "BA230S75", cyanate equivalent of about 232 g/eq., MEK solution with non-volatile content of 75% by mass), and 10 parts of a phenoxy resin (Mitsubishi Chemical Corporation's "YX7553BH30", a 1:1 mixture of MEK with a non-volatile content of 30% by mass and cyclohexanone) were added. Resin varnish 3 was prepared by mixing 8 parts of a silica gel (manufactured by Admatechs Co., Ltd., "SO-C2", average particle size 0.5 μm) surface-treated with a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-573"), 180 parts of spherical silica (manufactured by Admatechs Co., Ltd., "SO-C2", average particle size 0.5 μm), 4 parts of an amine-based curing accelerator (4-dimethylaminopyridine (DMAP), MEK solution with 5 mass % solids), and 1 part of a 1 mass % MEK solution of cobalt (III) acetylacetonate (manufactured by Tokyo Chemical Industry Co., Ltd., Co(III)), and dispersing the mixture uniformly using a high-speed rotary mixer.

<Formulation Example 4> Preparation of Resin Varnish 4 In Formulation Example 1,
1) The amount of biphenyl type epoxy resin ("NC3000L" manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: about 269 g/eq.) was changed from 20 parts to 5 parts,
2) 10 parts of a bixylenol type epoxy resin ("YX4000HK" manufactured by Mitsubishi Chemical Corporation) was further used.
3) 5 parts of an alicyclic epoxy resin (Daicel Corporation's "Celloxide 2021P", epoxy equivalent: about 137 g/eq.) was further used;
4) The amount of triazine skeleton-containing phenolic curing agent (DIC Corporation's "LA-3018-50P", active group equivalent of about 151 g/eq., 2-methoxypropanol solution with non-volatile content of 50%) was changed from 10 parts to 5 parts,
5) The amount of active ester compound (DIC Corporation's "HPC-8000-65T", active ester group equivalent of about 223 g/eq., toluene solution with non-volatile content of 65%) was changed from 50 parts to 30 parts,
6) 180 parts of spherical silica (Admatechs'"SO-C2", average particle size 0.5 μm) surface-treated with a silane coupling agent (Shin-Etsu Chemical Co., Ltd.'s "KBM-573") was replaced with 100 parts of spherical silica (Denka's "UFP-30", average particle size 0.3 μm) surface-treated with a silane coupling agent (Shin-Etsu Chemical Co., Ltd.'s "KBM-573");
7) Further, 15 parts of a maleimide resin containing an aromatic ring skeleton directly bonded to the nitrogen atom of the maleimide group (manufactured by Nippon Kayaku Co., Ltd., "MIR-3000-70MT") was used,
8) In addition, 5 parts of a styryl resin (manufactured by Mitsubishi Gas Chemical Company, Inc., "OPE-2St 1200") was used.
Resin varnish 4 was prepared in the same manner as in Formulation Example 1 except for the above.

<Formulation Example 5> Preparation of Resin Varnish 5 In Formulation Example 1,
1) The amount of spherical silica (Admatechs' SO-C2, average particle size 0.5 μm) surface-treated with a silane coupling agent (Shin-Etsu Chemical's KBM-573) was changed from 180 parts to 50 parts.
2) 5 parts of a phenoxy resin ("YX7553BH30" manufactured by Mitsubishi Chemical Corporation, a 1:1 solution of MEK and cyclohexanone with a non-volatile content of 30% by mass) was further used;
3) 2 parts of rubber particles ("Staphyloid AC3816N" manufactured by Aica Kogyo Co., Ltd.) were further used.
Resin varnish 5 was prepared in the same manner as in Formulation Example 1 except for the above.

<Formulation Example 6> Preparation of Resin Varnish 6 In Formulation Example 1,
1) The amount of spherical silica (Admatechs' SO-C2, average particle size 0.5 μm) surface-treated with a silane coupling agent (Shin-Etsu Chemical's KBM-573) was changed from 180 parts to 330 parts.
2) 8 parts of a phenoxy resin ("YX7553BH30" manufactured by Mitsubishi Chemical Corporation, a 1:1 solution of MEK and cyclohexanone having a nonvolatile content of 30% by mass) was further used.
Resin varnish 6 was prepared in the same manner as in Formulation Example 1 except for the above.

<Measurement of Glass Transition Temperature and Linear Thermal Expansion Coefficient of Cured Product of Resin Composition Layer>
A glass cloth-based epoxy resin double-sided copper-clad laminate (Panasonic Corporation's "R5715ES", thickness 0.7 mm, 255 mm square) was placed on the release agent-treated surface of a release agent-treated PET film (Lintec Corporation's "501010", thickness 50 μm, 240 mm square) and the four sides were fixed with polyimide adhesive tape (width 10 mm) (hereinafter sometimes referred to as "fixed PET film").

The resin varnishes 1 to 6 prepared in formulation examples 1 to 6 were applied to the release-treated surface of the "fixed PET film" using a die coater so that the thickness of the resin composition layer after drying was 40 μm, and then dried at 80°C to 120°C (average 100°C) for 10 minutes to obtain a resin sheet. The resin composition layer was then thermally cured in a 190°C oven for 90 minutes. After thermal curing, the polyimide adhesive tape was peeled off, and the cured product was removed from the glass cloth-based epoxy resin double-sided copper-clad laminate, and the PET film ("501010" manufactured by Lintec Corporation) was also peeled off to obtain a sheet-like cured product. The obtained cured product is referred to as the "cured product for evaluation."

The cured product for evaluation was cut into a test piece with a width of about 5 mm and a length of about 15 mm, and a thermomechanical analysis was performed by a tensile load method using a thermomechanical analyzer (Rigaku's "Thermo Plus TMA8310"). In detail, the test piece was mounted on the thermomechanical analyzer, and then measured twice consecutively under the measurement conditions of a load of 1 g and a heating rate of 5°C/min. In the second measurement, the glass transition temperature (Tg; °C) and the average linear thermal expansion coefficient (CTE; ppm/°C) in the range from 25°C to 150°C were calculated, and the evaluation was performed according to the following criteria.
Good: The average thermal expansion coefficient is 40 ppm/°C or less. Bad: The average thermal expansion coefficient is more than 40 ppm/°C.

<Measurement of Melt Viscosity of Resin Composition Layer at 90° C.>
Resin varnishes 1 to 6 obtained in Formulation Examples 1 to 6 were applied to the release surface of a release-treated polyethylene terephthalate film ("AL5" manufactured by Lintec Corporation, thickness 38 μm) as a protective film using a die coater so that the thickness of the resin composition layer was 40 μm, and dried at 80 to 120° C. (average 100° C.) for 6 minutes. After peeling off the protective film, 25 sheets of the same resin composition layer were stacked to obtain a resin composition layer laminate having a thickness of 1.25 mm. Next, the resin composition layer laminate was punched out to a diameter of 20 mm in the stacking direction to prepare a measurement sample. The prepared measurement samples were measured for dynamic viscoelasticity using a dynamic viscoelasticity measuring device (UBM "Rheogel-G3000") under the following measurement conditions: starting temperature from 60°C to 200°C, heating rate of 5°C/min, measurement temperature interval of 2.5°C, vibration frequency of 1 Hz, and strain of 5 deg. From the obtained melt viscosity curve, the melt viscosity (poise) at 90°C was determined, and judgment was made according to the following judgment criteria.
◯: Melt viscosity at 90° C. is 5,000 poise or more and 100,000 poise or less.
×: The melt viscosity at 90° C. is less than 5,000 poise or exceeds 100,000 poise.

＊表中、（Ａ）成分の含有量は、樹脂組成物層中の不揮発成分を１００質量％とした場合の含有量を表す。

*In the table, the content of component (A) represents the content when the total amount of non-volatile components in the resin composition layer is taken as 100 mass %.

Example 1: Preparation of resin sheet 1 with metal foil On the release surface of a release-treated polyethylene terephthalate film ("AL5" manufactured by Lintec Corporation, thickness 38 μm) which is a protective film, resin varnish 1 was applied by a die coater so that the thickness of the resin composition layer was 40 μm, and dried at 80 to 120 ° C. (average 100 ° C.) for 6 minutes. Next, a carrier-attached copper foil ("Microthin MT18Ex" manufactured by Mitsui Mining & Smelting Co., Ltd., ultra-thin copper foil with a thickness of 3 μm/carrier copper foil with a thickness of 18 μm, maximum height roughness (Rz) 4900 nm) having a carrier copper foil and an ultra-thin copper foil on the surface of the resin composition layer was laminated using a roll laminator ("FIRST LAMINATOR VA-770H" manufactured by Taisei Laminator Co., Ltd.) at a roll pressure of 0.25 MPa, a feed speed of 0.3 m/min, and a roll temperature of 90 ° C. to obtain a resin sheet 1 with metal foil.

<Example 2> Preparation of resin sheet 2 with metal foil In Example 1,
1) Change Resin Varnish 1 to Resin Varnish 2,
2) A carrier-attached copper foil having a carrier copper foil and an ultra-thin copper foil ("Microthin MT18Ex" manufactured by Mitsui Mining & Smelting Co., Ltd., ultra-thin copper foil with a thickness of 3 μm/carrier copper foil with a thickness of 18 μm, maximum roughness in height (Rz) of 4900 nm) was changed to a copper foil ("JDLC" manufactured by JX Mining & Smelting Co., Ltd., copper foil with a thickness of 12 μm, maximum roughness in height (Rz) of 8200 nm).
A resin sheet 2 with a metal foil was obtained in the same manner as in Example 1 except for the above points.

Example 3 Preparation of Resin Sheet 3 with Metal Foil In Example 1, Resin Varnish 1 was changed to Resin Varnish 3. A resin sheet 3 with a metal foil was obtained in the same manner as in Example 1 except for the above points.

Example 4 Preparation of Resin Sheet 4 with Metal Foil In Example 1, Resin Varnish 1 was changed to Resin Varnish 4. A resin sheet 4 with a metal foil was obtained in the same manner as in Example 1 except for the above points.

Comparative Example 1: Preparation of Resin Sheet 5 with Metal Foil In Example 2, Resin Varnish 2 was changed to Resin Varnish 5. A resin sheet 5 with a metal foil was obtained in the same manner as in Example 2 except for the above points.

Comparative Example 2: Preparation of resin sheet 6 with metal foil In Example 1, the carrier-attached copper foil ("Microthin MT18Ex" manufactured by Mitsui Mining & Smelting Co., Ltd., 3 μm-thick ultra-thin copper foil/18 μm-thick carrier copper foil, maximum height roughness (Rz) 4900 nm) having a carrier copper foil and an ultra-thin copper foil was changed to a film with a metal film described in Japanese Patent No. 5633124 (a film in which a 1 μm-thick cellulose layer and a 0.5 μm-thick copper layer are formed in this order on a 38 μm-thick polyethylene terephthalate film, maximum height roughness (Rz) 300 nm). A resin sheet 6 with a metal foil was obtained in the same manner as in Example 2 except for the above points.

Comparative Example 3: Preparation of Resin Sheet 7 with Metal Foil In Comparative Example 2, Resin Varnish 2 was changed to Resin Varnish 6. Except for the above, the same procedure as Comparative Example 2 was followed, but since the melt viscosity of Resin Varnish 6 was high, it was not possible to apply Resin Varnish 6, and it was impossible to laminate the film with the metal film using a roll laminator. That is, in Comparative Example 3, Resin Varnish 6 could not be applied onto the protective film, and therefore it was not possible to laminate the film with the metal film to the resin composition layer.

<Metal foil maximum height roughness (Rz) measurement>
The carrier copper foil and ultrathin copper foil used in the examples and comparative examples (Mitsui Mining & Smelting Co., Ltd.'s "Microthin MT18Ex", 3 μm thick ultrathin copper foil/18 μm thick carrier copper foil), copper foil (JX Mining & Smelting Co., Ltd.'s "JDLC", 12 μm thick copper foil), and metal film-attached film described in Patent No. 5633124 (a film in which a 1 μm thick cellulose layer and a 0.5 μm thick copper layer are formed in this order on a 38 μm thick polyethylene terephthalate film) were measured using a non-contact surface roughness meter (Beeco Instruments'"WYKONT3300") in VSI mode with a 50x lens to obtain a measurement range of 121 μm x 92 μm. The Rz value was calculated from the numerical value obtained. Measurements were performed at 10 points spaced 3 cm or more apart from each other, and the average value was calculated.

<Measurement of peel strength between metal foil and resin composition layer, and evaluation of blistering after lamination>
(1) Preparation of the Undercoated Inner Layer Substrate A glass cloth-based epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.8 mm, Panasonic "R1515A") having copper foil on the surface was prepared. The copper foil on the surface of this laminate was etched with a microetching agent (Mech "CZ8101") to a copper etching amount of 1 μm, and roughening treatment was performed. After that, it was dried at 190° C. for 30 minutes to prepare the undercoated inner layer substrate.

(2) Measurement of peel strength The undercoated inner layer substrate was cut into a size of 30 mm x 120 mm, and a double-sided adhesive tape (Nichiban Co., Ltd.'s "Nistack NW-25") was attached to the substrate. After peeling off the release paper from the double-sided adhesive tape, the protective film was peeled off from the resin sheet with metal foil obtained in the examples and comparative examples, and the resin composition layer was attached so as to be in contact with the double-sided adhesive tape.

After peeling off the carrier foil in Examples 1, 3, and 4, and after removing the polyethylene terephthalate film and cellulose layer of the protective film in Comparative Examples 2 and 3, the four sides of Example 2 and Comparative Example 1 were sealed with reverse embossed copper foil conductive tape (3245, manufactured by 3M Japan) to prevent the plating solution from entering.

Next, copper sulfate plating was performed until the total thickness of the metal foil became 20 μm, and drying was performed at 130 ° C. for 30 minutes. Thereafter, a cutter was used to make a cut with a width of 10 mm and a length of 100 mm, and one end was peeled off and gripped with a gripper (Autocom type testing machine "AC-50C-SL" manufactured by TSE Co., Ltd.), and the load (kgf / cm) when peeling 20 mm in the vertical direction at a speed of 50 mm / min at room temperature was measured in accordance with JIS C6481, and judgment was performed according to the following judgment criteria. In addition, in Comparative Examples 1 and 2, peeling occurred between the resin composition layer and the double-sided adhesive tape, and the peel strength was 1.28 kgf / cm, so it was inferred that the peel strength between the metal foil and the resin composition layer was higher than 1.28 kgf / cm. In addition, in Comparative Example 3, since it was not possible to apply resin varnish 6, it was not possible to bond the metal foil to the resin composition layer, and the peel strength could not be measured.
○: The peel strength is 0.01 kgf/cm or more and less than 0.30 kgf/cm. ×: The peel strength is less than 0.01 kgf/cm or exceeds 0.30 kgf/cm, or a test piece cannot be prepared.

(2) Evaluation of blistering after lamination The resin sheets with metal foil obtained in the examples and comparative examples were laminated on both sides of the substrate-treated inner layer substrate using a vacuum hot press machine (Kitagawa Seiki Co., Ltd., VH1-1603) so that the resin composition layer was in contact with the substrate-treated inner layer substrate. The pressing conditions were a reduced pressure of 1×10 ⁻³ MPa or less, a pressure condition of 20 kgf/cm ² , and heating conditions of the first stage pressing at a temperature of 100° C. and a time of 30 minutes, and the second stage pressing at a temperature of 190° C. and a time of 120 minutes, to obtain an evaluation substrate. The evaluation substrate was cut into small pieces of 100 mm×50 mm and evaluated by visual observation according to the following evaluation criteria. In Comparative Example 3, since it was not possible to apply the resin varnish 6, it was not possible to bond the metal foil to the resin composition layer, and it was not possible to evaluate the blistering after lamination.
A: No abnormality whatsoever in the small pieces.
×: The small pieces are abnormally swollen.

<Evaluation of void continuity>
The resin sheets with metal foil obtained in the examples and comparative examples were cut into 20 mm x 20 mm, and the protective film was peeled off and then placed in a glass beaker containing 50 mL of pure water. Next, the glass beaker containing the resin sheet with metal foil was placed in a desiccator, and the pressure was reduced to 10 kPa using a diaphragm vacuum pump and held for 10 minutes. After that, the pressure was gradually returned to atmospheric pressure over about 30 seconds. When the resin sheet with metal foil was immersed in water, the water penetrated into the voids in the resin sheet with metal foil, and the color of the voids where the water penetrated changed. When the discolored areas spread throughout the resin sheet with metal foil, it was evaluated that the voids were continuous. In Comparative Example 3, since it was not possible to apply the resin varnish 6, it was not possible to bond the metal foil to the resin composition layer, and it was not possible to evaluate the continuity of the voids.
○: Continuous voids: Water has penetrated into the voids.
×: No voids or the voids are discontinuous, and water does not penetrate into the voids.

＊表中、（Ａ）成分の含有量は、樹脂組成物層中の不揮発成分を１００質量％とした場合の含有量を表す。

*In the table, the content of component (A) represents the content when the total amount of non-volatile components in the resin composition layer is taken as 100 mass %.

REFERENCE SIGNS LIST 1 Resin sheet with metal foil 2 Metal foil 2a First surface 21 Protrusion 22 Void 3 Resin composition layer 4 Protective film

Claims (10)

A resin sheet with a metal foil, comprising a metal foil having a first surface and a resin composition layer bonded to the first surface of the metal foil,
The maximum height roughness (Rz) of the first surface of the metal foil is 1000 nm or more;
The resin composition layer contains (A) an inorganic filler,
(A) the content of the inorganic filler is 40% by mass or more and 80% by mass or less, when the non-volatile components of the resin composition layer are taken as 100% by mass,
The melt viscosity of the resin composition layer at 90° C. is 5,000 poise or more and 100,000 poise or less,
A resin sheet with a metal foil, wherein the peel strength between the metal foil and the resin composition layer is 0.01 kgf/cm or more and 0.3 kgf/cm or less. The resin sheet with metal foil according to claim 1, having voids continuously formed at the interface between the first surface of the metal foil and the resin composition layer. The resin sheet with metal foil according to claim 1, wherein the resin composition layer contains (B) an epoxy resin. The resin sheet with metal foil according to claim 1, wherein the resin composition layer contains (C) a curing agent. The resin sheet with metal foil according to claim 1, wherein the linear thermal expansion coefficient of the cured resin composition layer is 40 ppm/°C or less. The resin sheet with metal foil according to claim 1, which has a protective film on the side of the resin composition layer that is not bonded to the metal foil. The resin sheet with metal foil according to claim 6, wherein the protective film is release-treated. The resin sheet with metal foil according to claim 1, wherein the metal foil is copper foil. A circuit board comprising an insulating layer formed from a cured resin composition layer of the resin sheet with metal foil according to any one of claims 1 to 8, and a conductor layer formed from the metal foil of the resin sheet with metal foil according to any one of claims 1 to 8. A semiconductor device including the circuit board according to claim 9.

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