Circuit board manufacturing method

Abstract

To provide a new technique capable of giving a circuit board having an insulation layer having good adhesion to a conductor layer, even if an insulation layer is formed using a resin composition layer having a high inorganic filler content and thickness of 15 μm or less.SOLUTION: A method includes a step (I) of laminating a resin sheet having a support and a resin composition layer which is provided on the support and has an inorganic filler content of 60 mass% or more and thickness of 15 μm or less, on a base material, so that the resin composition layer is joined to the base material, a step (II) of thermosetting the resin composition layer, and forming an insulation layer, and a step (III) of peeling the support, in this order, wherein a water vapor permeation coefficient of the support calculated from a water permeation degree of the support measured under the condition that a temperature of 40°C and a relative humidity difference of 90% by a method according to JIS K 7129 is 0.5 g / m2 mm-1 24h or less, and the step (II) subjects the resin composition layer to heating treatment of holding the temperature at a temperature T1, and then subjects the resin composition layer to heating treatment of holding the temperature at a temperature T2 higher than the temperature T1.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a circuit board.

Background Art

[0002] A resin composition containing a thermosetting resin and its curing agent has been widely used as an insulating material for circuit boards such as printed wiring boards and rewiring boards for semiconductor packages because it provides a cured product with excellent insulation properties, heat resistance, adhesion, etc.

[0003] On the other hand, with the recent increase in communication speed, insulating materials for circuit boards are required to have excellent dielectric properties (low dielectric tangent) in order to reduce transmission loss when operating in a high-frequency environment.Moreover, in order to suppress the occurrence of cracks and circuit distortion due to the difference in thermal expansion between the insulating layer and the conductor layer in the circuit board, or to suppress the occurrence of warping when forming a large-area insulating layer in the manufacture of circuit boards such as wafer-level packages (WLP) and panel-level packages (PLP), an insulating material with a low coefficient of thermal expansion is required. As an insulating material exhibiting good dielectric properties and a low coefficient of thermal expansion, a resin composition with a high content of inorganic fillers such as silica particles is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a circuit board manufacturing technology, a manufacturing method by a build-up method in which an insulating layer and a conductor layer (circuit layer) are alternately stacked is known. In the manufacturing method by the build-up method, generally, a resin composition layer is laminated on a base material using a resin sheet or the like, and the resin composition layer is cured to form an insulating layer. Thereafter, the insulating layer is roughened (desmear treatment) and subjected to a plating process to provide a conductor layer and form a wiring pattern.

[0006] The inventors of the present invention have found that when forming an insulating layer using a resin composition having a high inorganic filler content in order to achieve good dielectric properties and a low thermal expansion coefficient, if a thin resin composition layer is used for reducing the thickness of the circuit board, the adhesion between the insulating layer and the conductor layer may not be sufficiently obtained. In particular, it was confirmed that when a high amount of inorganic filler is blended in a thin resin composition layer having a thickness of 15 μm or less, the deterioration of the adhesion between the insulating layer and the conductor layer becomes remarkable.

[0007] An object of the present invention is to provide a novel technology that can provide a circuit board having an insulating layer with good adhesion to a conductor layer even when an insulating layer is formed using a resin composition layer having a thickness of 15 μm or less and a high inorganic filler content.

Means for Solving the Problems

[0008] As a result of intensive studies on the above problems, the inventors of the present invention have found that the above problems can be solved by a manufacturing method of a circuit board having the following configuration, and have completed the present invention.

[0009] That is, the present invention includes the following contents. <1> (I) A step of laminating a resin sheet including a support and a resin composition layer provided on the support, having an inorganic filler content of 60% by mass or more and a thickness of 15 μm or less, on the base material so that the resin composition layer is joined to the base material, (II) A step of thermally curing the resin composition layer to form an insulating layer, and (III) A step of peeling the support, A manufacturing method of a circuit board including these steps in this order, The water vapor transmission coefficient of the support, calculated from the water vapor transmission rate of the support measured under conditions of 40°C and a relative humidity difference of 90% using a method compliant with JIS K7129, is 0.5 g / m². 2 ·mm -1 • Less than 24 hours A method comprising, in step (II), subjecting the resin composition layer to a heat treatment held at a temperature T1, and then to a heat treatment held at a temperature T2 higher than T1. <2> The temperature T2 is 150°C or higher. <1> Methods used. <3> The difference between temperature T1 and temperature T2, T2-T1, is 20°C or more. <1> or <2> Methods used. <4> The temperature T1 is 50°C or higher. <1> ~ <3> The method described in any of the following. <5> In step (II), the resin composition layer is heated to a temperature T2 at a heating rate of 0.5°C / min or more and 30°C / min or less. <1> ~ <4> The method described in any of the following. <6> The resin composition layer contains a thermosetting resin. <1> ~ <5> The method described in any of the following. <7> The resin composition layer contains one or more curing agents selected from the group consisting of active ester curing agents, phenol curing agents, naphthol curing agents, and carbodiimide curing agents. <1> ~ <6> The method described in any of the following. <8> The process further includes forming via holes in the insulating layer with a laser, <1> ~ <7> The method described in any of the following. <9> The process further includes forming a conductive layer on the surface of the insulating layer. <1> ~ <8> The method described in any of the following. <10> The peel strength between the insulating layer and the conductive layer is 0.3 kgf / cm or more. <9> Methods used. [Effects of the Invention]

[0010] According to the present invention, even when forming an insulating layer using a resin composition layer with a thickness of 15 μm or less and a high inorganic filler content, it is possible to provide a novel technology that can yield a circuit board with an insulating layer having good adhesion to the conductor layer. [Modes for carrying out the invention]

[0011] Before describing in detail the method for manufacturing the circuit board of the present invention, we will first describe the resin sheet used in the manufacturing method.

[0012] <Resin sheet> In the method for manufacturing a circuit board of the present invention, a resin sheet is used, comprising a support and a resin composition layer provided on the support, the inorganic filler content being 60% by mass or more and the thickness being 15 μm or less. The water vapor transmission coefficient of the support, calculated from the water vapor transmission rate of the support measured under conditions of 40°C and a relative humidity difference of 90% in accordance with JIS K7129, is 0.5 g / m². 2 ·mm -1 It is characterized by being 24 hours or less.

[0013] The following describes preferred embodiments from the viewpoint of more effectively enjoying the effects of the present invention.

[0014] -Support- The inventors have found that even when forming an insulating layer using a resin composition layer with a thickness of 15 μm or less and a high inorganic filler content, it is important to use a resin sheet equipped with a support having a water vapor permeability coefficient of a certain value or less in order to obtain an insulating layer with good adhesion to the conductor layer.

[0015] In detail, the water vapor transmission rate (g / m³) of the support was measured under conditions of 40°C and a relative humidity difference of 90% using a method compliant with JIS K7129. 2 The water vapor transmission coefficient of the support (g / m³) is calculated by multiplying the thickness of the support (mm) by the 24h (24h) value. 2 ·mm -1 (24h) is 0.5g / m 2 ·mm-1 · It is important that it is below 24 h. Even when forming an insulating layer using a resin composition layer with a thickness of 15 μm or less and a high inorganic filler content, from the viewpoint of providing an insulating layer with even better adhesion to the conductor layer, and further from the viewpoint of providing an insulating layer with a low surface roughness after roughening treatment (desmear treatment), the water vapor transmission coefficient of the above-mentioned support is preferably 0.45 g / m 2 · mm -1 · below 24 h, more preferably 0.4 g / m 2 · mm -1 · below 24 h, still more preferably 0.35 g / m 2 · mm -1 · below 24 h, 0.3 g / m 2 · mm -1 · below 24 h, 0.28 g / m 2 · mm -1 · below 24 h, 0.26 g / m 2 · mm -1 · below 24 h, 0.24 g / m 2 · mm -1 · below 24 h, 0.22 g / m<与えられた 2 · mm -1 · below 24 h, or 0.2 g / m 2 · mm -1 · It is below 24 h. The lower limit of the water vapor transmission coefficient is not particularly limited. For example, 0.05 g / m 2 · mm -1 · 24 h or more, 0.06 g / m 2 · mm -1 · 24 h or more, 0.08 g / m 2 · mm -1 · 24 h or more, 0.1 g / m 2 · mm -1 · It may be 2h or more, etc.

[0016] Examples of the support that satisfies such a water vapor transmission coefficient include, for example, (1) a base film with a water vapor transmission coefficient of 0.5 g / m 2 · mm -1 · below 24 h, (2) by providing a release layer on the base film, the overall water vapor transmission coefficient is 0.5 g / m 2 · mm -1(3) A base film with a release layer exhibiting a water vapor transmission coefficient of 24h or less, (4) a barrier layer on the base film, resulting in an overall value of 0.5 g / m 2 ·mm -1 (4) A base film with a barrier layer exhibiting a water vapor transmission coefficient of 24h or less, and a base film with a release layer, by providing a barrier layer on the side opposite to the release layer, the overall value is 0.5 g / m². 2 ·mm -1 Examples include supports having a layered structure of a release layer / base film / barrier layer exhibiting a water vapor permeability coefficient of 24h or less.

[0017] Examples of base films used as the support include thermoplastic resin films, metal foils, and release paper, with thermoplastic resin films and metal foils being preferred, and thermoplastic films (including those with a barrier layer) being particularly preferred. When forming via holes in the insulating layer with a laser or the like, it is desirable to form the via holes with a support to reduce damage to the surface of the insulating layer. However, when a thermoplastic film is used as the support, there is no need for pretreatment such as blackening treatment as with metal foil, and via holes can be easily formed with a laser.

[0018] When using a thermoplastic resin film as the base film, examples of thermoplastic resins include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylics such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketones, and polyimides. Among these, polyethylene terephthalate, polyethylene naphthalate, and polyimides are preferred.

[0019] When using a metal foil as the base film, examples of metal foils include copper foil and aluminum foil, with copper foil being preferred. As for the copper foil, foil made of single-metal copper may be used, or foil made of an alloy of copper with another metal (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

[0020] The base film may have a matte finish, corona treatment, or antistatic treatment applied to the surface that bonds with the resin composition layer. Alternatively, as mentioned above, a base film with a release layer on one side (the surface that bonds with the resin composition layer) may be used as the base film. Examples of release agents used for the release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. Commercially available base films with a release layer may be used, for example, PET films having a release layer mainly composed of an alkyd resin-based release agent, such as "SK-1", "AL-5", and "AL-7" from Lintec Corporation, "Lumirror T60" from Toray Industries, Inc., "Purex" from Teijin Corporation, and "Unipeel" from Unitika Corporation.

[0021] The thickness of the base film is not particularly limited as long as a support that satisfies the above-mentioned water vapor transmission coefficient can be obtained, but is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 12 μm or more, 14 μm or more, or 15 μm or more, with an upper limit of preferably 75 μm or less, more preferably 60 μm or less, and even more preferably 50 μm or less. When using a base film with a release layer, it is preferable that the overall thickness of the base film with the release layer is within the above range.

[0022] As mentioned above, the support may be equipped with a barrier layer. By providing a barrier layer, it is possible to suppress the permeation of water vapor, and a support that satisfies the above-mentioned water vapor permeability coefficient can be easily obtained. The barrier layer is not particularly limited as long as it satisfies the above-mentioned water vapor permeability coefficient together with the base film, but examples include inorganic films and organic films. Examples of inorganic films include metal foil such as aluminum and copper; silica vapor-deposited films; silicon nitride films; silicon oxide films; magnesium oxide films, etc. Examples of organic films include polyvinyl alcohol films, ethylene-vinyl alcohol copolymer films, and polyvinylidene chloride films. The barrier layer may have a single-layer structure or a multi-layer structure, for example, it may have a multi-layer structure composed of an inorganic film and an organic film.

[0023] Methods for forming inorganic films include, for example, chemical vapor deposition using heat, plasma, ultraviolet light, etc., and physical vapor deposition using methods such as evaporation and sputtering. Methods for forming organic films include, for example, coating organic compounds onto a substrate using coating equipment such as a die coater, comma coater, gravure coater, or bar coater.

[0024] The thickness of the barrier layer is not particularly limited as long as it satisfies the above-mentioned water vapor transmission coefficient together with the base film, but from the viewpoint of significantly obtaining the effects of the present invention, it is preferably 0.1 μm or more, more preferably 0.2 μm or more, 0.4 μm or more, or 0.5 μm or more, even more preferably 0.6 μm or more, 0.8 μm or more, or 1 μm or more, and its upper limit is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less.

[0025] The barrier layer may be bonded to the base film via an adhesive layer. The adhesive that can be used for the adhesive layer is not particularly limited as long as it can bond the base film and the barrier layer, and any adhesive may be used. Examples of such adhesives include water-based, solvent-based, hot-melt, and active energy ray-curing adhesives that can be cured by active energy rays such as ultraviolet light.

[0026] The thickness of the adhesive layer is not particularly limited, but from the viewpoint of significantly obtaining the effects of the present invention, it is preferably 0.1 μm or more, more preferably 0.3 μm or more, even more preferably 0.5 μm or more, preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 5 μm or less.

[0027] -Resin composition layer- In this invention, a resin composition layer having an inorganic filler content of 60% by mass or more and a thickness of 15 μm or less is used.

[0028] From the viewpoint of providing an insulating layer exhibiting good dielectric properties and a low coefficient of thermal expansion, the content of inorganic filler in the resin composition layer is 60% by mass or more, when the non-volatile components in the resin composition layer are taken as 100% by mass. As mentioned above, the inventors have confirmed that when inorganic filler is highly incorporated in a thin resin composition layer with a thickness of 15 μm or less, the adhesion between the insulating layer and the conductor layer deteriorates significantly. In this regard, according to the method for manufacturing a circuit board of the present invention, which uses a resin sheet equipped with a support having a water vapor permeability coefficient within the above range and curing the resin composition layer under specific conditions as described later, it is possible to obtain an insulating layer with good adhesion to the conductor layer even when inorganic filler is highly incorporated in a thin resin composition layer with a thickness of 15 μm or less. For example, the content of inorganic filler in the resin composition layer may be increased to 65% by mass or more, 66% by mass or more, 68% by mass or more, or 70% by mass or more. The upper limit of the inorganic filler content is not particularly limited, but for example, it may be 90% by mass or less, 85% by mass or less, etc.

[0029] Examples of inorganic filler materials include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum silicate, 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 preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Spherical silica is preferred. Inorganic fillers may be used individually or in combination of two or more types.

[0030] Examples of commercially available inorganic fillers include "SP60-05" and "SP507-05" from Nippon Steel Chemical & Material Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", "YA010C", "SC2500SQ", "SO-C4", "SO-C2", and "SO-C1" from Admatex Co., Ltd.; "UFP-30", "DAW-03", and "FB-105FD" from Denka Co., Ltd.; "Silfil NSS-3N", "Silfil NSS-4N", and "Silfil NSS-5N" from Tokuyama Corporation; "Selfiers" and "MGH-005" from Taiheiyo Cement Corporation; and "Esferique" and "BA-1" from JGC Catalysts & Chemicals Co., Ltd.

[0031] The average particle size of the inorganic filler is not particularly limited, but is preferably 5 μm or less, more preferably 3 μm or less, or 2 μm or less, even more preferably 1 μm or less, 0.8 μm or less, or 0.7 μm or less. The lower limit of the average particle size is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.07 μm or more, 0.1 μm or more, or 0.2 μm or more. The average particle size of the inorganic filler can be measured by the laser diffraction-scattering method based on Mie scattering theory. Specifically, the particle size distribution of the inorganic filler can be created on a volume basis using a laser diffraction-scattering particle size distribution analyzer, and the median diameter can be used as the average particle size. A sample can be prepared by weighing 100 mg of inorganic filler and 10 g of methyl ethyl ketone into a vial and dispersing them using ultrasound for 10 minutes. The particle size distribution of the inorganic filler was measured using a laser diffraction particle size distribution analyzer with blue and red light source wavelengths, employing a flow cell method. The average particle size was calculated as the median diameter from the obtained particle size distribution. Examples of laser diffraction particle size distribution analyzers include the "LA-960" manufactured by Horiba, Ltd.

[0032] The specific surface area of ​​the inorganic filler is not particularly limited, but is preferably 0.1 m². 2 / g or more, more preferably 0.5m 2 / g or more, more preferably 1m 2 / g or more, 3m 2 / g or more or 5m 2 The specific surface area is 100 m² or more. The upper limit of the specific surface area is not particularly limited, but is preferably 100 m². 2 / g or less, more preferably 80m 2 / g or less, more preferably 60mg 2 / g or less, 50m 2 / g or less or 40m 2 The value is less than / g. The specific surface area of ​​the inorganic filler is obtained by adsorbing nitrogen gas onto the sample surface using a specific surface area measuring device (Macsorb HM-1210, manufactured by Mountec Co., Ltd.) according to the BET method, and then calculating the specific surface area using the BET multipoint method.

[0033] It is preferable that the inorganic filler is surface-treated with an appropriate surface treatment agent. Surface treatment can improve the moisture resistance and dispersibility of the inorganic filler. Examples of surface treatment agents include silane coupling agents such as vinyl-based silane coupling agents, epoxy-based silane coupling agents, styryl-based silane coupling agents, (meth)acrylic-based silane coupling agents, amino-based silane coupling agents, isocyanurate-based silane coupling agents, ureido-based silane coupling agents, mercapto-based silane coupling agents, isocyanate-based silane coupling agents, and acid anhydride-based silane coupling agents; alkoxysilane compounds such as methyltrimethoxysilane and phenyltrimethoxysilane; silazane compounds; and oligomers thereof. The surface treatment agent may be used alone or in combination of two or more types.

[0034] -Thermosetting resin- The resin composition layer preferably contains a thermosetting resin.

[0035] Examples of thermosetting resins include epoxy resins, benzocyclobutene resins, epoxy acrylate resins, urethane acrylate resins, urethane resins, cyanate resins, unsaturated polyester resins, melamine resins, and silicone resins. Thermosetting resins may be used individually or in combination of two or more types.

[0036] In particular, even when a high concentration of inorganic fillers is incorporated into a thin resin composition layer with a thickness of 15 μm or less, it is preferable that the thermosetting resin contains epoxy resin, from the viewpoint of providing an insulating layer with good adhesion to the conductor layer, and further from the viewpoint of providing an insulating layer with low surface roughness after roughening treatment (desmear treatment).

[0037] Examples of epoxy resins include bisphenol-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, 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, cyclohexanedimethanol-type epoxy resins, naphthylene ether-type epoxy resins, trimethylol-type epoxy resins, and tetraphenylethane-type epoxy resins. Bisphenol-type epoxy resins refer to epoxy resins having a bisphenol structure, and examples include bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, and bisphenol AF-type epoxy resins. Biphenyl-type epoxy resins refer to epoxy resins having a biphenyl structure, where the biphenyl structure may have substituents such as alkyl groups, alkoxy groups, or aryl groups. Therefore, bixylenol-type epoxy resins and biphenylaralkyl-type epoxy resins are also included in biphenyl-type epoxy resins. Epoxy resins may be used individually or in combination of two or more types.

[0038] As the epoxy resin, aromatic epoxy resins are preferred. Here, aromatic epoxy resins refer to epoxy resins that have an aromatic ring in their molecule.

[0039] The epoxy resin preferably has two or more epoxy groups in one molecule. When the non-volatile components of the epoxy resin are considered to be 100% by mass, the proportion of epoxy resin having two or more epoxy groups in one molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.

[0040] Epoxy resins include liquid epoxy resins at 20°C (hereinafter referred to as "liquid epoxy resins") and solid epoxy resins at 20°C (hereinafter referred to as "solid epoxy resins").

[0041] As the liquid epoxy resin, a liquid epoxy resin having two or more epoxy groups in one molecule is preferred.

[0042] Preferred liquid epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resins such as alicyclic epoxy resins having an ester skeleton, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, and epoxy resins having a butadiene structure.

[0043] Specific examples of liquid epoxy resins include DIC's "HP-4032," "HP-4032D," and "HP-4032SS" (naphthalene-type epoxy resin); Mitsubishi Chemical's "828US," "jER828EL," "825," and "Epicote 828EL" (bisphenol A-type epoxy resin); Mitsubishi Chemical's "jER807" and "1750" (bisphenol F-type epoxy resin); Mitsubishi Chemical's "jER152" (phenol novolac-type epoxy resin); and Mitsubishi Chemical's "630" and "630LSD" (p-aminophenol-type epoxy resin, glycidyl Examples include: luminamine-type epoxy resins; "ZX1059" from Nippon Steel Chemical & Material (a mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin); "EX-721" from Nagase ChemteX (glycidyl ester-type epoxy resin); "Celoxide 2021P" from Daicel Corporation (alicyclic epoxy resin with an ester skeleton); "PB-3600" from Daicel Corporation (epoxy resin with a butadiene structure); and "ZX1658" and "ZX1658GS" from Nippon Steel Chemical & Material (liquid 1,4-glycidylcyclohexane-type epoxy resins).

[0044] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups per molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups per molecule is more preferred.

[0045] Preferred solid epoxy resins include bixylenol-type epoxy resin, naphthalene-type epoxy resin, naphthalene-type tetrafunctional epoxy resin, cresol novolac-type epoxy resin, dicyclopentadiene-type epoxy resin, trisphenol-type epoxy resin, naphthol-type epoxy resin, biphenyl-type epoxy resin, naphthylene ether-type epoxy resin, anthracene-type epoxy resin, bisphenol A-type epoxy resin, bisphenol AF-type epoxy resin, and tetraphenylethane-type epoxy resin.

[0046] Specific examples of solid epoxy resins include DIC's "HP-4032H" (naphthalene-type epoxy resin); DIC's "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resins); DIC's "N-690" (cresol novolac-type epoxy resin); DIC's "N-695" (cresol novolac-type epoxy resin); DIC's "HP-7200HH", "HP-7200H", and "HP-7200" (dicyclopentadie epoxy resin). (Naphthylene ether type epoxy resin); DIC Corporation's "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthylene ether type epoxy resin); Nippon Kayaku Co., Ltd.'s "EPPN-502H" (trisphenol type epoxy resin); Nippon Kayaku Co., Ltd.'s "NC-7000-L" (naphthol novolac type epoxy resin); Nippon Kayaku Co., Ltd.'s "NC-3000-H", "NC-3000", "NC-300 "0-L", "NC-3100" (biphenyl type epoxy resin); "ESN475V" (naphthol type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN485" (naphthol novolac type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YL6121" (biphenyl type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX4000HK" (bixylenol type epoxy resin) manufactured by Mitsubishi Chemical Corporation; manufactured by Mitsubishi Chemical Corporation Examples include "YX8800" (anthracene-type epoxy resin); "PG-100" and "CG-500" from Osaka Gas Chemical Co., Ltd.; "YL7760" (bisphenol AF-type epoxy resin) from Mitsubishi Chemical Corporation; "YL7800" (fluorene-type epoxy resin) from Mitsubishi Chemical Corporation; "jER1010" (solid bisphenol A-type epoxy resin) from Mitsubishi Chemical Corporation; and "jER1031S" (tetraphenylethane-type epoxy resin) from Mitsubishi Chemical Corporation.

[0047] The resin composition layer may contain only a liquid epoxy resin, only a solid epoxy resin, or a combination of both. Even when a high concentration of inorganic filler is used in a thin resin composition layer with a thickness of 15 μm or less, it is preferable that the resin composition layer contains a solid epoxy resin from the viewpoint of providing an insulating layer with good adhesion to the conductive layer. When a combination of liquid epoxy resin and solid epoxy resin is used, their mass ratio (liquid epoxy resin:solid epoxy resin) is preferably 1:0.5 to 1:50, more preferably 1:1 to 1:30, and even more preferably 1:2 to 1:20.

[0048] The epoxy equivalent of the epoxy resin 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. The epoxy equivalent is the mass of the epoxy resin containing one equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0049] The weight-average molecular weight (Mw) of the epoxy resin is preferably 100 to 5000, more preferably 250 to 3000, and even more preferably 400 to 1500. The Mw of the epoxy resin can be measured as a polystyrene equivalent by gel permeation chromatography (GPC).

[0050] Even when a high concentration of inorganic filler is incorporated into a thin resin composition layer with a thickness of 15 μm or less, from the viewpoint of providing an insulating layer with even better adhesion to the conductive layer, the content of thermosetting resin in the resin composition layer is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, 20% by mass or more, or 25% by mass or more, when the total resin component in the resin composition layer is taken as 100% by mass. The upper limit of this content is not particularly limited and may be determined according to the properties required of the resin composition, but for example, it may be 80% by mass or less, 70% by mass or less, 65% by mass or less, or 60% by mass or less.

[0051] In the present invention, the term "resin component" in reference to the resin composition layer refers to the non-volatile components constituting the resin composition layer, excluding the inorganic filler described later.

[0052] -Hardening agent- The resin composition layer preferably contains a curing agent. The curing agent typically has the function of curing the resin composition layer by reacting with the thermosetting resin.

[0053] Examples of curing agents include active ester-based curing agents, phenol-based curing agents, naphthol-based curing agents, acid anhydride-based curing agents, cyanate ester-based curing agents, carbodiimide-based curing agents, and amine-based curing agents. The curing agent may be used alone or in combination of two or more types.

[0054] In particular, even when a high concentration of inorganic filler is incorporated into a thin resin composition layer with a thickness of 15 μm or less, it is preferable that the curing agent includes one or more selected from the group consisting of active ester curing agents, phenolic curing agents, naphthol curing agents, and carbodiimide curing agents, from the viewpoint of providing an insulating layer with good adhesion to the conductor layer, and further from the viewpoint of providing an insulating layer with low surface roughness after roughening treatment (desmear treatment). Therefore, in one embodiment, the resin composition layer includes one or more selected from the group consisting of active ester curing agents, phenolic curing agents, naphthol curing agents, and carbodiimide curing agents, and more preferably includes an active ester curing agent.

[0055] As the active ester curing agent, a compound having one or more active ester groups in one molecule can be used. Among these, 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 preferred as the active ester curing agent. The active ester curing agent is preferably 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 derived from a carboxylic acid compound is preferred, an active ester curing agent obtained from a carboxylic acid compound and a hydroxy compound is more preferred, and an active ester curing agent obtained from a carboxylic acid compound and an aromatic hydroxy compound is even more preferred.

[0056] As the carboxylic acid compound, either an aromatic carboxylic acid compound or an aliphatic carboxylic acid may be used, for example, benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, etc.

[0057] Examples of aromatic hydroxy compounds include (i) polyaddition products of unsaturated aliphatic cyclic compounds containing two double bonds in one molecule and phenols, (ii) various bisphenol compounds, (iii) aromatic polyols in which two or more hydroxyl groups are bonded to a carbon atom on an aromatic ring, and (iv) aromatic monools in which one hydroxyl group is bonded to a carbon atom on an aromatic ring. Examples of polyaddition products of unsaturated aliphatic cyclic compounds and phenols include polyaddition products of unsaturated aliphatic cyclic compounds such as dicyclopentadiene, tetrahydroindene, norbornadiene, limonene, and vinylcyclohexene with phenols that may have substituents (e.g., phenol, cresol, xylenol, ethylphenol, propylphenol, vinylphenol, allylphenol, phenylphenol, benzylphenol, halophenol, etc.), and specifically, for example, dicyclopentadiene-phenol polyadditions. Examples of bisphenol compounds include bisphenol A, bisphenol F, bisphenol AF, bisphenol AP, bisphenol B, bisphenol BP, bisphenol C, and bisphenol M. Examples of aromatic polyols, in which two or more hydroxyl groups are bonded to a carbon atom on an aromatic ring, include hydroquinone, resorcinol, catechol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, and phenol novolac. Examples of aromatic monools, in which one hydroxyl group is bonded to a carbon atom on an aromatic ring, include phenol, cresol, xylenol, ethylphenol, propylphenol, vinylphenol, allylphenol, phenylphenol, benzylphenol, halophenol, naphthol, methylnaphthol, dimethylnaphthol, ethylnaphthol, propylnaphthol, vinylnaphthol, allylnaphthol, phenylnaphthol, benzylnaphthol, and halonaphthol.

[0058] Suitable examples of active ester-based curing agents include active ester compounds containing a dicyclopentadiene-type diphenol structure, active ester compounds containing a naphthalene structure, active ester compounds containing an acetylated phenol novolac, and active ester compounds containing a benzoylated phenol novolac. Among these, active ester compounds containing a naphthalene structure and active ester compounds containing a dicyclopentadiene-type diphenol structure are more preferred. "Dicyclopentadiene-type diphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentalene-phenylene.

[0059] Commercially available active ester curing agents include, as active ester resins containing a dicyclopentadiene-type diphenol structure, "EXB-9451", "EXB-9460", "EXB-9460S", "HPC-8000-65T", "HPC-8000H-65TM", and "HPC-8000L-65TM" (manufactured by DIC Corporation); and as active ester resins containing a naphthalene structure, "EXB-8100L-65T", "EXB-8150-60T", "EXB-8150-62T", "EXB-9416-70BK", "HPC-8150-60T", and "HPC-8150-62T". Examples include "HP-B-8151-62T" and "HP-C-8151-62T" (manufactured by DIC Corporation); "EXB9401" (manufactured by DIC Corporation) as a phosphorus-containing active ester resin; "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester resin that is an acetylated phenol novolac; "YLH1026," "YLH1030," and "YLH1048" (manufactured by Mitsubishi Chemical Corporation) as active ester resins that are benzoylated phenol novolacs; and "PC1300-02-65MA" (manufactured by Air Water Corporation) as an active ester resin containing a styryl group and a naphthalene structure.

[0060] From the viewpoint of heat resistance and water resistance, phenolic and naphthol curing agents having a novolac structure are preferred. Furthermore, from the viewpoint of adhesion to the conductive layer, nitrogen-containing phenolic and nitrogen-containing naphthol curing agents are preferred, and triazine skeleton-containing phenolic and triazine skeleton-containing naphthol curing agents are more preferred.

[0061] Specific examples of phenol-based and naphthol-based curing agents include, for example, "MEH-7700," "MEH-7810," "MEH-7851," and "MEH-8000H" from Meiwa Kasei Co., Ltd.; "NHN," "CBN," and "GPH" from Nippon Kayaku Co., Ltd.; and "SN-170," "SN-180," "SN-190," "SN-475," "SN-485," "SN-495," "SN-495V," and "SN-37" from Nippon Steel Chemical & Material Co., Ltd. Examples include "5", "SN-395", "TD-2090", "TD-2090-60M", "LA-7052", "LA-7054", "LA-1356", "LA-3018", "LA-3018-50P", "EXB-9500", "HPC-9500", "KA-1160", "KA-1163", "KA-1165" from DIC Corporation, and "GDP-6115L", "GDP-6115H", "ELPC75" from Gun-ei Chemical Co., Ltd.

[0062] Specific examples of carbodiimide-based curing agents include Carbodilite® V-03 (carbodiimide group equivalent: 216 g / eq.), V-05 (carbodiimide group equivalent: 262 g / eq.), V-07 (carbodiimide group equivalent: 200 g / eq.), V-09 (carbodiimide group equivalent: 200 g / eq.) manufactured by Nisshinbo Chemical Corporation, and Stavaxol® P (carbodiimide group equivalent: 302 g / eq.) manufactured by Rhein Chemie.

[0063] Examples of acid anhydride-based curing agents include curing agents having one or more acid anhydride groups in one molecule. Specific examples of acid anhydride-based curing agents include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexen-1,2-dicarboxylic acid anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenone tetracarboxylic acid di Examples of acid anhydrides include anhydrides, biphenyltetracarboxylic acid dianhydride, naphthalenetetracarboxylic acid dianhydride, oxydiphthalic acid dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), and polymer-type acid anhydrides such as styrene-maleic acid resin copolymerized with styrene and maleic acid. A commercially available acid anhydride-based curing agent is "MH-700" manufactured by Shin Nippon Rika Co., Ltd.

[0064] 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-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl) thioether, and bis(4-cyanatephenyl) ether; polyfunctional cyanate resins derived from phenol novolacs and cresol novolacs, etc.; and prepolymers in which these cyanate resins are partially triazined. Specific examples of cyanate ester-based curing agents include "PT30" and "PT60" (phenol novolac type polyfunctional cyanate ester resin), "ULL-950S" (polyfunctional cyanate ester resin), "BA230", and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate is triazined and trimerized), all manufactured by Lonza Japan.

[0065] Examples of amine-based curing agents include curing agents having one or more amino groups in one molecule, such as aliphatic amines, polyetheramines, alicyclic amines, and aromatic amines. Specific examples of amine-based curing agents include 4,4'-methylenebis(2,6-dimethylaniline), diphenyldiaminosulfone, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxy Examples include bis(4-(4-aminophenoxy)phenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, etc. Commercial amine-based curing agents may also be used, such as "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD AA", "KAYAHARD AB", and "KAYAHARD AS" from Nippon Kayaku Co., Ltd., and "Epicure W" from Mitsubishi Chemical Corporation.

[0066] Even when a high concentration of inorganic filler is incorporated into a thin resin composition layer with a thickness of 15 μm or less, from the viewpoint of providing an insulating layer with good adhesion to the conductor layer, and further from the viewpoint of providing an insulating layer with low surface roughness after roughening treatment (desmear treatment), the content of curing agent in the resin composition is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, 30% by mass or more, or 35% by mass or more, when the resin component in the resin composition is considered as 100% by mass. The upper limit of the content is not particularly limited and may be determined according to the properties required of the resin composition, but for example, it may be 70% by mass or less, 65% by mass or less, or 60% by mass or less.

[0067] In particular, even when a high concentration of inorganic fillers is incorporated into a thin resin composition layer with a thickness of 15 μm or less, it is preferable that the curing agent includes an active ester-based curing agent, from the viewpoint of providing an insulating layer with even better adhesion to the conductor layer, and further from the viewpoint of providing an insulating layer with even lower surface roughness after roughening treatment (desmear treatment). When the resin composition layer includes an active ester-based curing agent as the curing agent, the content of the active ester-based curing agent in the curing agent is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, 75% by mass or more, or 80% by mass or more, when the non-volatile components of the curing agent are considered to be 100% by mass, from the viewpoint of enjoying the effects of the present invention and obtaining a cured product exhibiting particularly excellent dielectric properties. The upper limit of the content of the active ester-based curing agent in the curing agent is not particularly limited and may be 100% by mass, but may be, for example, 95% by mass or less, 90% by mass or less.

[0068] In the multilayer resin sheet of the present invention, when the resin composition layer contains an active ester-based curing agent as a curing agent, the mass ratio of the active ester-based curing agent to the thermosetting resin (active ester-based curing agent / thermosetting resin) is preferably 0.5 or higher, more preferably 0.6 or higher, even more preferably 0.7 or higher, or 0.75 or higher, from the viewpoint of enjoying the effects of the present invention and exhibiting particularly excellent dielectric properties. The upper limit of the mass ratio (active ester-based curing agent / thermosetting resin) may be, for example, 5 or less, 4.5 or less, 4 or less, etc.

[0069] -Thermoplastic resin- The resin composition layer may further contain a thermoplastic resin.

[0070] Examples of thermoplastic resins include phenoxy resin, polyvinyl acetal resin, polyolefin resin, polystyrene resin, polyimide resin, polyamide-imide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polyetheretherketone resin, and polyester resin. Thermoplastic resins may be used individually or in combination of two or more types.

[0071] The weight-average molecular weight (Mw) of the thermoplastic resin in terms of polystyrene is preferably 8,000 or more, more preferably 10,000 or more, and even more preferably 20,000 or more or 30,000 or more. The upper limit is preferably 100,000 or less, more preferably 70,000 or less, and even more preferably 60,000 or less. The Mw of the thermoplastic resin in terms of polystyrene is measured by the GPC method. Specifically, the Mw of the thermoplastic resin in terms of polystyrene can be calculated using a Shimadzu LC-9A / RID-6A measuring device, a Showa Denko Shodex K-800P / K-804L / K-804L column, and chloroform or the like as the mobile phase, with the column temperature measured at 40°C, and using a calibration curve for standard polystyrene.

[0072] 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 ends of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. Phenoxy resins may be used alone or in combination of two or more types. Specific examples of phenoxy resins include "1256" and "4250" (both phenoxy resins containing a bisphenol A skeleton), "YX8100" (phenoxy resin containing a bisphenol S skeleton), and "YX6954" (phenoxy resin containing a bisphenol acetophenone skeleton), all manufactured by Mitsubishi Chemical Corporation. Other examples include "FX280" and "FX293" from Nippon Steel Chemical & Material Corporation, and "YL7800BH40", "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290", and "YL7482" from Mitsubishi Chemical Corporation.

[0073] Examples of polyvinyl acetal resins include polyvinyl formal resin and polyvinyl butyral resin, with polyvinyl butyral resin being preferred. Specific examples of polyvinyl acetal resins include, for example, Denka's "Denka Butyral 4000-2," "Denka Butyral 5000-A," "Denka Butyral 6000-C," and "Denka Butyral 6000-EP," and Sekisui Chemical's Esrec BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series.

[0074] As the polyimide resin, a resin having an imide structure (preferably a cyclic imide structure) can be used. For example, an imidized product of an acid anhydride and a diamine compound or diisocyanate compound may be used. Specific examples of polyimide resins include "Ricacoat SN20" and "Ricacoat PN20" manufactured by Shin Nippon Rika Co., Ltd. Other specific examples of polyimide resins include linear polyimides obtained by reacting a bifunctional hydroxyl-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride (polyimides described in Japanese Patent Publication No. 2006-37083), and modified polyimides containing a polysiloxane skeleton (polyimides described in Japanese Patent Publication No. 2002-12667 and Japanese Patent Publication No. 2000-319386, etc.).

[0075] Specific examples of polyamide-imide resins include "Viromax HR11NN" and "Viromax HR16NN" manufactured by Toyobo Co., Ltd. Other specific examples of polyamide-imide resins include modified polyamide-imides such as "KS9100" and "KS9300" (polysiloxane skeleton-containing polyamide-imide) manufactured by Hitachi Chemical Co., Ltd.

[0076] Specific examples of polyethersulfone resins include "PES5003P" manufactured by Sumitomo Chemical Co., Ltd. Specific examples of polyphenylene ether resins include "OPE-2St 1200," an oligophenylene ether-styrene resin manufactured by Mitsubishi Gas Chemical Company. Specific examples of polyetheretherketone resins include "Sumiproi K" manufactured by Sumitomo Chemical Co., Ltd. Specific examples of polyetherimide resins include "Ultem" manufactured by GE.

[0077] Specific examples of polysulfone resins include Solvay Advanced Polymers' polysulfones "P1700" and "P3500".

[0078] Examples of polyolefin resins include ethylene-based copolymer resins such as low-density polyethylene, ultra-low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; and polyolefin-based elastomers such as polypropylene and ethylene-propylene block copolymer.

[0079] Examples of polystyrene resins include styrene homopolymers, copolymers of styrene and diene compounds (butadiene, isoprene, etc.), and their hydrogenated products.

[0080] Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polytrimethylene terephthalate resin, polytrimethylene naphthalate resin, and polycyclohexanedimethyl terephthalate resin.

[0081] When the resin composition layer contains a thermoplastic resin, even when a high concentration of inorganic filler is used in a thin resin composition layer with a thickness of 15 μm or less, the content of the thermoplastic resin is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, when the total resin component in the resin composition layer is considered to be 100% by mass. The upper limit is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0082] The resin composition layer may further contain one or more selected from the group consisting of radical polymerizable resins, curing accelerators, and polymerization initiators.

[0083] -Radical Polymerizable Resin- 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 per molecule. Examples of radical polymerizable resins include resins having one or more radical polymerizable unsaturated groups selected from maleimide, vinyl, allyl, styryl, vinylphenyl, acryloyl, methacryloyl, fumaroyl, and maleoil groups.

[0084] The type of maleimide resin is not particularly limited, as long as it has one or more (preferably two or more) maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrole-1-yl groups) per molecule. Examples of maleimide resins include: (1) maleimide resins containing an aliphatic skeleton (preferably an aliphatic skeleton with 36 carbon atoms derived from dimer amine) such as "BMI-3000J", "BMI-5000", "BMI-1400", "BMI-1500", "BMI-1700", and "BMI-689" (all manufactured by Desikner Molecules), and "SLK6895-T90" (manufactured by Shin-Etsu Chemical Co., Ltd.); (2) maleimide resins containing an indan skeleton as described in the Japan Institute of Invention and Innovation, Technical Report 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 Yamato Kasei Co., Ltd.), and "BMI-80" (manufactured by Kei-I Kasei Co., Ltd.).

[0085] The type of (meth)acrylic resin is not particularly limited as long as it has one or more (preferably two or more) (meth)acryloyl groups in one molecule, and may be a monomer or oligomer. Here, the term "(meth)acryloyl group" is a general term for acryloyl groups 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 Industry 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.).

[0086] The type of styryl resin is not particularly limited as long as it has one or more (preferably two or more) styryl groups or vinylphenyl groups in one molecule, and may be a monomer or oligomer. Examples of styryl resins include styrene monomer, as well as styryl resins such as "OPE-2St," "OPE-2St 1200," and "OPE-2St 2200" (all manufactured by Mitsubishi Gas Chemical Company).

[0087] When the resin composition layer contains a radical polymerizable resin, even when a high concentration of inorganic filler is used in a thin resin composition layer with a thickness of 15 μm or less, the content of the radical polymerizable resin in the resin composition layer is preferably 2% by mass or more, more preferably 4% by mass or more, and even more preferably 5% by mass or more, 6% by mass or more, 8% by mass or more, or 10% by mass or more, when the total resin component in the resin composition is considered to be 100% by mass. The upper limit of this content is not particularly limited and may be determined according to the properties required of the resin composition, but for example, it may be 50% by mass or less, 40% by mass or less, or 30% by mass or less.

[0088] -Curing accelerator- Examples of curing accelerators include amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, metal-based curing accelerators, and peroxide-based curing accelerators. Curing accelerators may be used individually or in combination of two or more types.

[0089] When the resin composition layer contains a curing accelerator, the content of the curing accelerator in the resin composition may be determined according to the required properties of the resin composition. However, even when a high concentration of inorganic filler is used in a thin resin composition layer with a thickness of 15 μm or less, from the viewpoint of providing an insulating layer with even better adhesion to the conductive layer, the content of the curing accelerator in the resin composition is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less, with the lower limit being 0.01% by mass or more, 0.05% by mass or more, 0.1% by mass or more, etc.

[0090] -Polymerization initiator- Examples of polymerization initiators include peroxides such as t-butylcumyl peroxide, t-butyl peroxyacetate, α,α'-di(t-butylperoxy)diisopropylbenzene, t-butyl peroxylaurate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyneodecanoate, and t-butyl peroxybenzoate.

[0091] Examples of commercially available polymerization initiators include NOF Corporation's "Perbutyl C," "Perbutyl A," "Perbutyl P," "Perbutyl L," "Perbutyl O," "Perbutyl ND," "Perbutyl Z," "Perbutyl P," and "Perbutyl D."

[0092] When the resin composition layer contains a polymerization initiator, the content of the polymerization initiator is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.03% by mass or more, when the resin component in the resin composition is considered to be 100% by mass, from the viewpoint of enjoying the effects of the present invention, and the upper limit is preferably 1% by mass or less, or 0.5% by mass or less.

[0093] -Optional additives- The resin composition layer may further contain any additives. Such additives include, for example, organic fillers such as rubber particles; organometallic compounds such as organocumeric compounds, organozinc compounds, and organocobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium dioxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentonite and montmorillonite; defoaming agents such as silicone-based defoaming agents, acrylic-based defoaming agents, fluorine-based defoaming agents, and vinyl resin-based defoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silane; triazole-based adhesion ferrants, tetrazole-based adhesion ferrants, and triadi Examples of additives include adhesion-improving agents such as phosphate-based adhesion-improving agents; antioxidants such as hindered phenol-based antioxidants; fluorescent whitening agents 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); dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; and stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic acid anhydride-based stabilizers. The content of such additives may be determined according to the properties required of the resin composition layer and, consequently, the insulating layer.

[0094] As mentioned above, the thickness of the resin composition layer is 15 μm or less from the viewpoint of providing a thin insulating layer and thereby contributing to the reduction of the circuit board's height. As mentioned above, the inventors have confirmed that when a high amount of inorganic filler is incorporated into a thin resin composition layer with a thickness of 15 μm or less, the adhesion between the insulating layer and the conductor layer deteriorates significantly. In this regard, according to the circuit board manufacturing method of the present invention, which uses a resin sheet equipped with a support having a water vapor permeability coefficient within the above range and curing the resin composition layer under specific conditions as described later, it is possible to obtain an insulating layer with good adhesion to the conductor layer even when a high amount of inorganic filler is incorporated into a thin resin composition layer with a thickness of 15 μm or less. For example, the thickness of the resin composition layer may be reduced to 14 μm or less, 12 μm or less, or 10 μm or less. The lower limit of the thickness of the resin composition layer can usually be 3 μm or more, 5 μm or more, etc.

[0095] In one embodiment, the resin sheet may further include any additional layer as needed. Such an additional layer may be, for example, a protective film provided on the side of the resin composition layer that is not bonded to the support (i.e., the side opposite to the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film, the adhesion of dust and other debris to the surface of the resin composition layer and scratches can be suppressed.

[0096] Resin sheets can be manufactured, for example, by applying a resin varnish prepared by directly using a liquid resin composition or by dissolving the resin composition in an organic solvent, coating it onto a support using a die coater or the like, and then drying it to form a resin composition layer.

[0097] Examples of organic solvents include those similar to those described as components of the resin composition. Organic solvents may be used individually or in combination of two or more.

[0098] Drying may be carried out by known methods such as heating or blowing hot air. The drying conditions are not particularly limited, but the resin composition layer should be dried so that the content of the organic solvent in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. Depending on the boiling point of the organic solvent in the resin composition or resin varnish, for example, when using a resin composition or resin varnish containing 30% to 60% by mass of organic solvent, the resin composition layer can be formed by drying at 50°C to 150°C for 1 to 10 minutes.

[0099] The resin sheet can be stored by rolling it up. If the resin sheet has a protective film, it can be used after removing the protective film.

[0100] The present invention will be described in detail below with reference to its preferred embodiments. However, the present invention is not limited to the embodiments and examples described below, and can be implemented with modifications as appropriate without departing from the scope of the claims and equivalents of the present invention.

[0101] [Manufacturing method for circuit boards] The method for manufacturing a circuit board of the present invention (hereinafter also simply referred to as "the method of the present invention") is: (I) A step of laminating a resin sheet comprising a support and a resin composition layer provided on the support, the resin composition layer having an inorganic filler content of 60% by mass or more and a thickness of 15 μm or less, onto a substrate such that the resin composition layer is bonded to the substrate. (II) A step of forming an insulating layer by thermal curing the resin composition layer, (III) Step of peeling off the support, A method for manufacturing a circuit board, comprising the following in this order: The water vapor transmission coefficient of the support, calculated from the water vapor transmission rate of the support measured under conditions of 40°C and a relative humidity difference of 90% using a method compliant with JIS K7129, is 0.5 g / m². 2 ·mm -1 • Less than 24 hours A method comprising, in step (II), subjecting the resin composition layer to a heat treatment held at a temperature T1, and then to a heat treatment held at a temperature T2 higher than T1.

[0102] As mentioned above, when forming an insulating layer using a resin composition with a high inorganic filler content to achieve good dielectric properties and a low coefficient of thermal expansion, the inventors have found that when a thin resin composition layer is used to reduce the height of the circuit board, sufficient adhesion between the insulating layer and the conductor layer may not be obtained. In particular, they have confirmed that when a high amount of inorganic filler is incorporated into a thin resin composition layer with a thickness of 15 μm or less, the deterioration of adhesion between the insulating layer and the conductor layer becomes significant.

[0103] In contrast, the present invention, which uses a resin sheet equipped with a support having a water vapor permeability coefficient within the above-mentioned specific range, and forms an insulating layer by thermal curing the resin composition layer under the above-mentioned specific conditions, can provide an insulating layer with good adhesion to the conductor layer even when a high amount of inorganic filler is incorporated into a thin resin composition layer with a thickness of 15 μm or less. Furthermore, it can provide an insulating layer with low surface roughness after roughening treatment (desmear treatment).

[0104] In the case where the insulating layer exhibited poor adhesion to the conductor layer, observation of the surface of the insulating layer after roughening treatment (desmear treatment) revealed that a large amount of inorganic filler was present and exposed on the surface of the insulating layer, likely due to the high proportion of inorganic filler. In contrast, for the insulating layer obtained by the present invention, which uses a resin sheet with a support having a water vapor permeability coefficient within the specified range and heat-cures the resin composition layer under the specified conditions, it was confirmed that less inorganic filler was present and exposed on the surface of the insulating layer after roughening treatment, and that a resin-rich phase tended to be present. Thus, it is presumed that the insulating layer obtained by the present invention retains the bulk properties such as good dielectric properties and low thermal expansion coefficient due to the high proportion of inorganic filler, while a resin-rich phase is formed on its surface, reproducing a surface that contributes to good adhesion to the conductor layer. Furthermore, it has been confirmed that when a high concentration of inorganic filler is incorporated into a thin resin composition layer with a thickness of 15 μm or less, simply using a resin sheet equipped with a support having a water vapor permeability coefficient within the above-mentioned specific range, or simply forming an insulating layer by thermal curing the resin composition layer under the above-mentioned specific conditions, does not result in an insulating layer with good adhesion to the conductor layer (see the comparative examples described later). In other words, the problems and effects of the present invention are synergistically solved and achieved only when a resin sheet equipped with a support having a water vapor permeability coefficient within the above-mentioned specific range is used, and an insulating layer is formed by thermal curing the resin composition layer under the above-mentioned specific conditions.

[0105] The following describes each step.

[0106] -Process (I)- In step (I), a resin sheet comprising a support and a resin composition layer provided on the support, the resin composition layer having an inorganic filler content of 60% by mass or more and a thickness of 15 μm or less, is laminated onto the substrate such that the resin composition layer is bonded to the substrate.

[0107] The resin sheet used in process (I) is as described in the <Resin Sheet> section above, including the water vapor transmission coefficient of the support and the composition and thickness of the resin composition layer. If the resin sheet has a protective film, process (I) is carried out after peeling off the protective film to expose the resin composition layer.

[0108] In process (I), the "substrate" on which the resin sheet is laminated mainly refers to substrates such as glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates, or substrates on which a patterned conductive layer (circuit) is formed on one or both sides of the substrate. Furthermore, an inner layer circuit board of an intermediate product on which an insulating layer and / or conductive layer is to be further formed when manufacturing a circuit board is also included in the "substrate" as defined in this invention.

[0109] Furthermore, when manufacturing a redistribution substrate for a semiconductor package, the circuit board is used as the first chip (Chip-1). stWhen manufacturing using the ) method, a semiconductor wafer equipped with a circuit element having a predetermined function and an electrode pad surface on which multiple electrode pads electrically connected to this circuit element are formed may be used as the "substrate". Silicon (Si) wafers are preferred as semiconductor wafers, but are not limited to them, and wafers such as gallium arsenide (GaAs), indium phosphide (InP), gallium phosphide (GaP), gallium nitride (GaN), gallium tellurium (GaTe), zinc selenium (ZnSe), and silicon carbide (SiC) wafers may also be used. The chip 1st method is a method in which a semiconductor chip is first provided and a redistribution layer is formed on its electrode pad surface (for example, Japanese Patent Publication No. 2002-289731, Japanese Patent Publication No. 2006-173345, etc.). In such a chip 1st manufacturing method, especially when manufacturing a fan-out package, first the semiconductor wafer is separated into individual pieces, each semiconductor chip is placed on a carrier substrate spaced apart from each other, then resin-sealed, and a redistribution layer is formed on the exposed electrode pad surface and the surrounding sealing resin layer (for example, Japanese Patent Publication No. 2012-15191, Japanese Patent Publication No. 2015-126123, etc.). Circuit board redistribution layer 1st (RDL-1 st When manufacturing using the ) method, the "substrate" can be a substrate with a release layer or a substrate on which a conductive layer (circuit) has been patterned. The redistribution layer 1st method is a method in which a redistribution layer is first provided, and a semiconductor chip is provided on the redistribution layer in such a state that its electrode pad surface can be electrically connected to the redistribution layer (for example, Japanese Patent Publication No. 2015-35551, Japanese Patent Publication No. 2015-170767, etc.). In the redistribution layer 1st method, after the semiconductor chip is provided on the redistribution layer, the redistribution layer is exposed by peeling off the substrate with the release layer. As the substrate with the release layer, any known substrate used when manufacturing a circuit board with the redistribution layer 1st method may be used, and the type is not particularly limited, but examples include a glass substrate with a release layer, a metal substrate with a release layer, a plastic substrate with a release layer, etc.

[0110] Lamination of the substrate and the resin sheet can be performed by heating and pressing the resin sheet onto the substrate from the support side. Examples of the heat-pressing member used to heat-press the resin sheet onto the substrate (hereinafter also referred to as the "heat-pressing member") include a heated metal plate (such as a SUS end plate) or a metal roll (such as a SUS roll). The heat-pressing member may be pressed directly onto the resin sheet, or it may be pressed via an elastic material such as heat-resistant rubber to ensure that the resin sheet conforms sufficiently to the surface irregularities of the substrate.

[0111] Lamination of the substrate and resin sheet may be carried out by a vacuum lamination method. In the vacuum lamination method, the heat-pressing temperature is preferably in the range of 60°C to 160°C, more preferably in the range of 80°C to 140°C, the heat-pressing pressure is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably in the range of 0.29 MPa to 1.47 MPa, and the heat-pressing time is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. Lamination may preferably be carried out under reduced pressure conditions of 26.7 hPa or less.

[0112] Lamination can be performed using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include vacuum pressure laminators manufactured by Meiki Seisakusho Co., Ltd., vacuum applicators manufactured by Nikko Materials Co., Ltd., and batch-type vacuum pressure laminators.

[0113] After lamination, the laminated resin sheets may be smoothed by pressing a heat-sealing member from the support side under normal pressure (atmospheric pressure). The pressing conditions for the smoothing process can be the same as the heat-sealing conditions for lamination. The smoothing process can be performed using a commercially available laminator. Lamination and smoothing may be performed continuously using the commercially available vacuum laminator mentioned above.

[0114] -Process (II)- In step (II), the resin composition layer is heat-cured to form an insulating layer.

[0115] The method of the present invention is characterized in that, in step (II), the resin composition layer is subjected to a heat treatment to be held at a temperature T1, and then subjected to a heat treatment to be held at a temperature T2 that is higher than temperature T1. Hereinafter, the heat treatment to be held at temperature T1 will be referred to as the "pre-cure step," and the heat treatment to be held at temperature T2 will be referred to as the "post-cure step."

[0116] --Pre-cure process (heat treatment held at temperature T1)-- Typically, prior to the pre-cure step, the resin composition layer is at a heating start temperature T0, which is lower than the temperature T1. The heating start temperature T0 may be, for example, room temperature. Therefore, step (II) may include a step of heating the resin composition layer from the heating start temperature T0 to temperature T1 before the pre-cure step. From the viewpoint of significantly obtaining the effects of the present invention, the heating rate in this heating step is preferably 0.5°C / min or more, more preferably 1°C / min or more, even more preferably 1.5°C / min or more, even more preferably 2°C / min or more, and particularly preferably 2.5°C / min or more, with an upper limit of preferably 30°C / min or less, more preferably 25°C / min or less, even more preferably 20°C / min or less, even more preferably 15°C / min or less, and particularly preferably 10°C / min or less. The heating rate in this heating step may be constant or may be varied.

[0117] In the pre-cure process, the resin composition layer is subjected to a heat treatment that maintains it at a temperature T1. The heating temperature T1 in this pre-cure process is set within a temperature range that is higher than room temperature and lower than temperature T2. From the viewpoint of significantly obtaining the effects of the present invention, the specific range of the heating temperature T1 is preferably 50°C or higher, more preferably 60°C or higher, even more preferably 70°C or higher, and even more preferably 80°C or higher, with an upper limit of preferably less than 150°C, more preferably 140°C or lower, and even more preferably 130°C or lower. In the pre-cure process, maintaining the resin composition layer at temperature T1 is not limited to maintaining the temperature of the resin composition layer at a constant temperature, but also includes the possibility of the temperature of the resin composition layer fluctuating within a range that does not significantly impair the effects of the present invention. For example, in the pre-cure process, the temperature of the resin composition layer may fluctuate within a range of ±10°C, ±8°C, or ±5°C. However, even if the temperature of the resin composition layer fluctuates in this way, it is preferable that the temperature of the resin composition layer during the pre-cure process remains within the above preferred range, for example, between 50°C and 150°C. In particular, it is especially preferable that the temperature of the resin composition layer remains constant and does not fluctuate during the pre-cure process.

[0118] The time for holding the resin composition layer at heating temperature T1 during the pre-curing process depends on the composition of the resin composition layer and the value of heating temperature T1, but from the viewpoint of significantly obtaining the effects of the present invention, it is preferably 10 minutes or more, more preferably 15 minutes or more, and even more preferably 20 minutes or more, with an upper limit of preferably 150 minutes or less, more preferably 120 minutes or less, and even more preferably 120 minutes or less.

[0119] --Post-cure process (heat treatment held at temperature T2)-- Typically, before the post-cure step, the resin composition layer is at a temperature lower than T2. ​​Therefore, step (II) may include a step of raising the temperature of the resin composition layer to T2 after the pre-cure step and before the post-cure step. From the viewpoint of significantly obtaining the effects of the present invention, the heating rate in this heating step is preferably 0.5°C / min or more, more preferably 1°C / min or more, even more preferably 1.5°C / min or more, even more preferably 2°C / min or more, and particularly preferably 2.5°C / min or more, with an upper limit of preferably 30°C / min or less, more preferably 25°C / min or less, even more preferably 20°C / min or less, even more preferably 15°C / min or less, and particularly preferably 10°C / min or less. Therefore, in one embodiment, in step (II), the resin composition layer is heated to T2 at a heating rate of 0.5°C / min or more and 30°C / min or less. The heating rate in this heating step may be constant or varied.

[0120] In the post-curing process, the resin composition layer is subjected to a heat treatment to maintain it at a temperature T2. The heating temperature T2 in the post-curing process is set to a higher temperature than the temperature T1. From the viewpoint of significantly obtaining the effects of the present invention, the specific range of the heating temperature T2 is preferably 150°C or higher, more preferably 155°C or higher, even more preferably 160°C or higher, and particularly preferably 170°C or higher, with an upper limit of preferably 250°C or lower, more preferably 230°C or lower, even more preferably 220°C or lower, even more preferably 210°C or lower, and particularly preferably 200°C or lower. In the post-curing process, maintaining the resin composition layer at temperature T2 includes not only maintaining the temperature of the resin composition layer at a constant temperature, but also allowing the temperature of the resin composition layer to fluctuate within a range that does not significantly impair the effects of the present invention. For example, in the post-curing process, the temperature of the resin composition layer may fluctuate within a range of ±10°C, ±8°C, or ±5°C. However, even if the temperature of the resin composition layer fluctuates in this way, it is preferable that the temperature of the resin composition layer during the post-curing process remains within the above preferred range, for example, between 150°C and 250°C. In particular, it is especially preferable that the temperature of the resin composition layer remains constant and does not fluctuate during the post-curing process.

[0121] The difference T2-T1 between the heating temperature T1 in the pre-cure process and the heating temperature T2 in the post-cure process is preferably within a specific range from the viewpoint of significantly obtaining the effects of the present invention. Specifically, the difference T2-T1 is preferably 20°C or higher, more preferably 30°C or higher, and even more preferably 40°C or higher, with an upper limit of preferably 150°C or lower, more preferably 140°C or lower, even more preferably 130°C or lower, and particularly preferably 120°C or lower. When the temperature of the resin composition layer fluctuates in the pre-cure process and / or post-cure process, it is preferable that the difference between the median temperature of the resin composition in the pre-cure process and the median temperature of the resin composition in the post-cure process is within the above range.

[0122] The time for holding the resin composition layer at the heating temperature T2 during the post-curing process depends on the composition of the resin composition layer and the value of the heating temperature T2. However, from the viewpoint of significantly obtaining the effects of the present invention, it is preferably 10 minutes or more, more preferably 15 minutes or more, and even more preferably 20 minutes or more, with an upper limit of preferably 150 minutes or less, and more preferably 120 minutes or less.

[0123] After the heat treatment at temperature T1 in the pre-cure process, the resin composition layer may be cooled and then subjected to heat treatment at heating temperature T2 in the post-cure process. Alternatively, after the heat treatment at temperature T1 in the pre-cure process, the resin composition layer may be subjected to heat treatment at temperature T2 in the post-cure process without cooling.

[0124] The heat treatment in the pre-cure process and the heat treatment in the post-cure process may be carried out using the same heat treatment apparatus. Alternatively, the heat treatment in the pre-cure process may be carried out using a first heat treatment apparatus, and the heat treatment in the post-cure process may be carried out using a second heat treatment apparatus different from the first heat treatment apparatus. The heat treatment apparatus is not particularly limited as long as it can heat-cur the resin composition layer. Examples of heat treatment apparatuses include ovens and hot presses. For example, after performing the heat treatment in the pre-cure process using an oven adjusted to temperature T1, the laminate of the substrate and resin sheet may be transferred to an oven adjusted to temperature T2 to perform the heat treatment in the post-cure process. Alternatively, after performing the heat treatment in the pre-cure process using a heat treatment apparatus with a temperature programmable, the temperature may be raised from T1 to T2 to perform the heat treatment in the post-cure process.

[0125] Step (II) may include any additional steps in addition to the pre-cure and post-cure steps and the preceding heating steps described above. For example, step (II) may include a step of subjecting the resin composition layer to a heat treatment that maintains it at a temperature other than T1 and T2. In other words, step (II) is not limited to a two-step heat treatment, but may include three or more steps of heat treatment.

[0126] Step (II) is preferably carried out under a nitrogen atmosphere. If the nitrogen atmosphere contains oxygen, the oxygen concentration in the nitrogen atmosphere is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and may be 0% by mass.

[0127] The pressure conditions of the nitrogen atmosphere in which step (II) is carried out may be at atmospheric pressure or under reduced pressure. In one example, the specific pressure conditions of the nitrogen atmosphere are preferably 0.1 hPa or higher, more preferably 1.3 hPa or higher, and the upper limit is preferably 5000 hPa or lower, more preferably 2500 hPa or lower.

[0128] -Process (III)- In step (III), the support is peeled off. This exposes the insulating layer.

[0129] The support may be peeled off by pulling it relative to the insulating layer. For example, the support may be peeled off by transporting the insulating layer and substrate while the support is fixed. Alternatively, the support may be peeled off by pulling it while the insulating layer and substrate are fixed.

[0130] The temperature at which step (III) is performed is not particularly limited. From the viewpoint of reducing the energy required for manufacturing the circuit board, step (III) is usually performed at room temperature or a temperature close to it. Therefore, usually, after step (II), step (III) is performed after the laminate consisting of the substrate, insulating layer and support has been cooled. The temperature at which step (III) is performed is preferably in the range of 10°C to 40°C. The rate of cooling when cooling from temperature T2 is not particularly limited, but is preferably 0.5°C / min or more, more preferably 1°C / min or more, even more preferably 1.5°C / min or more, even more preferably 2°C / min or more, and particularly preferably 2.5°C / min or more, with an upper limit of preferably 30°C / min or less, more preferably 25°C / min or less, even more preferably 20°C / min or less, even more preferably 15°C / min or less, and particularly preferably 10°C / min or less.

[0131] The method of the present invention may include other steps, as long as it includes steps (I) to (III) above in that order. For example, the method of the present invention may further include (A) forming via holes in an insulating layer with a laser, (B) roughening (desmearing) the insulating layer, and (C) forming a conductive layer on the surface of the insulating layer.

[0132] In process (A), via holes are formed in the insulating layer using a laser.

[0133] For example, a carbon dioxide laser (CO2 laser), UV-YAG laser, or excimer laser may be used as a laser light source for forming via holes in the insulating layer.

[0134] The laser processing conditions (e.g., laser wavelength, pulse count, pulse width, power) are not particularly limited as long as they can form via holes with a good via shape and low internal smearing, and may be appropriately determined within the range of general processing conditions according to the specifications of the laser processing machine used.

[0135] The dimensions and shape of via holes may be determined as appropriate according to the design of the circuit board. For example, the shape of a via hole is not particularly limited, but is generally circular (or nearly circular). The top diameter of the via hole is preferably 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less, and its lower limit may be, for example, 2 μm or more, 4 μm or more, 5 μm or more. Here, the top diameter of the via hole refers to the diameter of the via hole opening on the insulating layer surface.

[0136] In the method of the present invention, step (A) may be performed after step (II), for example, between step (II) and step (III), or after step (III).

[0137] In step (B), the insulating layer is roughened (desmeared). This removes resin residue (smear) from within the via holes. The procedure and conditions for the desmearing process are not particularly limited, and known procedures and conditions commonly used when forming the insulating layer of a circuit board can be adopted. For example, the desmearing process can be performed by carrying out swelling with a swelling solution, desmearing (roughening) with an oxidizing agent solution, and neutralization with a neutralizing solution in that order.

[0138] The swelling solution used for desmearing is not particularly limited, but examples include alkaline solutions and surfactant solutions, and is preferably an alkaline solution, with sodium hydroxide solution and potassium hydroxide solution being more preferred. Examples of commercially available swelling solutions include "Swelling Dip Securigant P" and "Swelling Dip Securigant SBU" manufactured by Atotec Japan. The swelling treatment with the swelling solution is not particularly limited, but can be carried out, for example, by immersing the insulating layer in a swelling solution at 30°C to 90°C for 1 to 20 minutes. From the viewpoint of suppressing the swelling of the resin of the insulating layer to an appropriate level, it is preferable to immerse the insulating layer in a swelling solution at 40°C to 80°C for 5 to 15 minutes.

[0139] The oxidizing agent solution used for desmearing is not particularly limited, but examples include an alkaline permanganate solution obtained by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide. The roughening treatment with an oxidizing agent solution such as an alkaline permanganate solution is preferably carried out by immersing the insulating layer in the oxidizing agent solution heated to 60°C to 100°C for 10 to 30 minutes. Furthermore, the concentration of permanganate in the alkaline permanganate solution is preferably 5% to 10% by mass. Examples of commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securigans P" manufactured by Atotec Japan.

[0140] Furthermore, an acidic aqueous solution is preferred as the neutralizing solution used in desmear treatment, and a commercially available example is "Reduction Securigant P" manufactured by Atotec Japan. Neutralization treatment with a neutralizing solution can be carried out by immersing the treated surface, which has been roughened with an oxidizing agent, in a neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From the viewpoint of workability, it is preferable to immerse the object that has been roughened with an oxidizing agent in a neutralizing solution at 40°C to 70°C for 5 to 20 minutes.

[0141] Here, if the desmear treatment is performed after the support has been peeled off, that is, if step (B) is performed after step (III), the desmear treatment also serves as a roughening treatment for the exposed surface of the insulating layer. As mentioned above, according to the method of the present invention, a resin-rich phase tends to be formed on the surface of the insulating layer after the roughening treatment, which is advantageous because it can reproduce a surface that contributes to adhesion with the conductor layer. Therefore, in one embodiment, the desmear treatment is performed after the support has been peeled off.

[0142] Next, in step (C), a conductive layer is formed on the surface of the insulating layer.

[0143] In one embodiment, the conductor layer may be formed by plating. For example, a conductor layer having a desired wiring pattern can be formed by plating the surface of the insulating layer using conventionally known techniques such as the semi-additive method or the fully additive method. From the viewpoint of ease of manufacture, it is preferable to form it by the semi-additive method. An example of forming the conductor layer by the semi-additive method is shown below.

[0144] First, a plating seed layer is formed on the surface of the insulating layer by electroless plating. The plating seed layer includes at least a conductive seed layer. The conductive seed layer is a layer that functions as an electrode in the electroplating method. The conductive material constituting the conductive seed layer is not particularly limited as long as it exhibits sufficient conductivity, but preferred examples include copper, palladium, gold, platinum, silver, aluminum, and their alloys. The plating seed layer may also include a diffusion barrier layer. The diffusion barrier layer is a layer that prevents the conductive material constituting the conductive seed layer from diffusing into the insulating layer and causing dielectric breakdown. The material constituting the diffusion barrier layer is not particularly limited as long as it can suppress and prevent the diffusion of the conductive material constituting the conductive seed layer, but preferred examples include titanium, tungsten, tantalum, and their alloys. After forming a conductive layer on the plating seed layer in a desired pattern, any unnecessary parts other than the conductive layer formation area are removed by etching or the like. At this time, the smaller the thickness of the plating seed layer, the easier it is to remove the unnecessary parts of the plating seed layer, and the less erosion of the conductive pattern when removing the unnecessary parts, which is advantageous for realizing fine wiring. The thickness of the plating seed layer is preferably 1000 nm (1 μm) or less, more preferably 800 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, or 300 nm or less. In the method of the present invention, an insulating layer with low surface roughness can be realized, so the thickness of the plating seed layer may be even thinner. For example, the thickness of the plating seed layer may be 250 nm or less, 200 nm or less, 150 nm or less, 140 nm or less, 120 nm or less, or 100 nm or less. When the plating seed layer includes a diffusion barrier layer, the "thickness of the plating seed layer" in the present invention refers to the average thickness of the entire plating seed layer, including not only the conductive seed layer but also the diffusion barrier layer.

[0145] The plating seed layer may be formed by dry plating or by wet plating. Examples of dry plating include physical vapor deposition (PVD) methods such as sputtering, ion plating, and vacuum deposition, and chemical vapor deposition (CVD) methods such as thermal CVD and plasma CVD. Examples of wet plating include electroless plating. From the viewpoint of forming a thin plating seed layer with a more uniform thickness, dry plating or electroless plating is preferred.

[0146] Next, an etching resist (plating resist) is formed on the formed plating seed layer, exposing a portion of the plating seed layer corresponding to the desired wiring pattern. After forming a metal layer on the exposed plating seed layer by electroplating, the etching resist is removed. The conductive material used for the metal layer is not particularly limited. In a preferred embodiment, the metal layer includes one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The metal layer may be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from alloys of two or more metals selected from the above group (e.g., nickel-chromium alloy, copper-nickel alloy, and copper-titanium alloy).

[0147] Subsequently, the unnecessary plating seed layer can be removed by etching or other means to form a conductor layer having the desired wiring pattern (hereinafter also referred to as the "conductor pattern").

[0148] The thickness of the conductor layer depends on the desired circuit board design, but is generally 3 μm to 35 μm, preferably 5 μm to 30 μm.

[0149] According to the method of the present invention, it is possible to form fine conductor circuits with L / S ratios of, for example, 5 / 5 μm or less, 4 / 4 μm or less, 3 / 3 μm or less, 2 / 2 μm or less, 1.5 / 1.5 μm or less, or 1 / 1 μm or less, while maintaining good adhesion between the insulating layer and the conductor layer.

[0150] According to the method of the present invention, even when forming an insulating layer using a resin composition layer with a thickness of 15 μm or less and a high inorganic filler content, an insulating layer with good adhesion to the conductor layer can be obtained. For example, the peel strength to the conductor layer measured by the method described in the section "<Measurement of Adhesion (Peel Strength)>" below can preferably be 0.26 kgf / cm or more, 0.28 kgf / cm or more, or 0.3 kgf / cm or more.

[0151] According to the method of the present invention, even when forming an insulating layer using a resin composition layer with a thickness of 15 μm or less and a high inorganic filler content, an insulating layer with low surface roughness can be obtained after roughening treatment (desmear treatment). For example, the arithmetic mean roughness Ra measured by the method described in the section "Measurement of Arithmetic Mean Roughness Ra" below is preferably 500 nm or less, 400 nm or less, 300 nm or less, 250 nm or less, 200 nm or less, or 150 nm or less.

[0152] If necessary, the formation of the insulating layer and conductive layer in steps (I) to (III) and steps (A) to (C) above may be repeated to form a multilayer circuit board.

[0153] As described above, the circuit boards manufactured by the method of the present invention can be suitably used as printed wiring boards and circuit boards for semiconductor packages (circuit boards for semiconductor packages). The semiconductor package using the circuit board manufactured by the method of the present invention may be either a fan-in type package or a fan-out type package. When the semiconductor package is a fan-out type package, it is advantageous because, in addition to the inherent feature of fan-out type packages that allows for the formation of a redistribution layer over a large area, it is possible to form a conductor circuit over a large area with a fine pattern. [Examples]

[0154] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the following description, "parts" means "parts by mass" unless otherwise specified. Unless otherwise specified, the experiments were conducted at room temperature and atmospheric pressure.

[0155] [Example 1] Ten parts of bisphenol-type epoxy resin (ZX1059, manufactured by Nippon Steel Chemical & Material Co., Ltd., a 1:1 mixture of bisphenol A and bisphenol F, epoxy equivalent 169) and fifty parts of naphthol-type epoxy resin (ESN475V, manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent approximately 330) were heated and dissolved in 40 parts of solvent naphtha with stirring. This mixture was then cooled to room temperature to prepare the epoxy resin solution composition.

[0156] This epoxy resin dissolution composition contains 5 parts of phenoxy resin (Mitsubishi Chemical Corporation's "YX7553BH30," a 1:1 solution of methyl ethyl ketone (MEK) with 30% by mass of nonvolatile components and cyclohexanone), 5 parts of triazine skeleton-containing cresol novolac resin (DIC Corporation's "LA3018-50P," a 2-methoxypropanol solution with approximately 151 reactive groups and 50% nonvolatile components), 70 parts of active ester curing agent (DIC Corporation's "HPC-8000-65T," a toluene solution with approximately 223 reactive groups and 65% by mass of nonvolatile components), and (meth)acrylic resin (Shin Nakamura Chemical Co., Ltd.'s "A-DOG," ( 20 parts of meth)acryloyl group equivalent (156), 15 parts of carbodiimide-based curing agent (Nisshinbo Chemical Co., Ltd. "V-03", carbodiimide group equivalent (216), toluene solution with 50% by mass of nonvolatile components), 6 parts of curing accelerator (1-benzyl-2-phenylimidazole (1B2PZ), MEK solution with 10% by mass of nonvolatile components), 2 parts of polymerization initiator (NOF Corporation "Parkmil D", MEK solution with 20% of nonvolatile components), and spherical silica surface-treated with amino-based silane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573") (Admatex Co., Ltd. "SO-C2", average particle size 0.5 μm, specific surface area 5.9 m²). 2 370 parts of ( / g), 10 parts of cyclohexanone, and 10 parts of MEK were mixed and uniformly dispersed in a high-speed rotary mixer to prepare resin varnish 1.

[0157] The support was prepared by using a PET film (Lintec "AL5", 40 μm thick) with a release layer on one side, and a 2 μm thick organic barrier layer (polyvinyl alcohol) on the side opposite to the release layer of the film (support layer structure: release layer / PET film / organic barrier layer). Resin varnish 1 was uniformly applied to the release layer of this support so that the thickness of the resin composition layer after drying was 10 μm. Then, the resin varnish 1 was dried at 80°C to 100°C (average 90°C) for 2 minutes to obtain a resin sheet containing the support and the resin composition layer.

[0158] [Example 2] 25 parts of liquid bisphenol A type epoxy resin (Mitsubishi Chemical Corporation's "jER828EL", epoxy equivalent 180), 20 parts of biphenyl type epoxy resin (Nippon Kayaku Co., Ltd.'s "NC-3000L", epoxy equivalent 269), 15 parts of naphthalene type tetrafunctional epoxy resin (DIC Corporation's "HP-4700", epoxy equivalent 162), dicyclopentadiene type epoxy resin (DIC Corporation's "HP-7200HH", epoxy equivalent 280), and 30 parts of phenoxy resin (Mitsubishi Chemical Corporation's "YX6954", weight-average molecular weight 38000, a 1:1 solution of MEK and cyclohexanone with 30% by mass of nonvolatile components) were heated and dissolved in 15 parts of MEK and 15 parts of cyclohexanone while stirring. To this, 40 parts of a phenol novolac curing agent (DIC Corporation's "LA-7054", phenolic hydroxyl group equivalent 124, MEK solution with 60% non-volatile components), 0.1 parts of a curing accelerator (Shikoku Chemicals Co., Ltd.'s "2E4MZ", 2-ethyl-4-methylimidazole), and spherical silica (Spherical silica (Admatex Corporation's "SO-C2", average particle size 0.5 μm, specific surface area 5.9 m²) surface-treated with an amino-based silane coupling agent (Shin-Etsu Chemical Co., Ltd.'s "KBM573")) were added. 2 180 parts of ( / g) were mixed and uniformly dispersed in a high-speed rotary mixer to prepare resin varnish 2.

[0159] The support was prepared by using a PET film (Lintec Corporation's "AL5", 40 μm thick) with a release layer on one side, and a 2 μm thick organic barrier layer (polyvinyl alcohol) on the side opposite to the release layer. A resin varnish 2 was uniformly applied to the release layer of this support so that the thickness of the resin composition layer after drying was 10 μm. The resin varnish 2 was then dried at 80°C to 100°C (average 90°C) for 2 minutes to obtain a resin sheet containing the support and the resin composition layer.

[0160] [Example 3] A PEN film (Teonex Q83, manufactured by Toyobo Co., Ltd., 25 μm thick) with a release layer on one side was prepared as a support. The resin varnish 1 described above was uniformly applied to the release layer of this support so that the thickness of the resin composition layer after drying was 10 μm. Then, the resin varnish 1 was dried at 80°C to 100°C (average 90°C) for 2 minutes to obtain a resin sheet containing the support and the resin composition layer.

[0161] [Example 4] A polyimide (PI) film with a release layer (Ube Industries, Ltd.'s "UPIREX-S", 13 μm thick) was prepared as a support. The resin varnish 1 described above was uniformly applied to the release layer of this support so that the thickness of the resin composition layer after drying was 10 μm. Then, the resin varnish 1 was dried at 80°C to 100°C (average 90°C) for 2 minutes to obtain a resin sheet containing the support and the resin composition layer.

[0162] [Comparative Example 1] A PET film (Lintec Corporation's "AL5", 38 μm thick) with a release layer on one side was prepared as a support. The resin varnish 1 described above was uniformly applied to the release layer of this support so that the thickness of the resin composition layer after drying was 10 μm. Then, the resin varnish 1 was dried at 80°C to 100°C (average 90°C) for 2 minutes to obtain a resin sheet containing the support and the resin composition layer.

[0163] [Comparative Example 2] A PET film (Lintec Corporation's "AL5", 40 μm thick) with a release layer on one side was prepared, and a 2 μm thick organic barrier layer (polyvinyl alcohol) was provided on the side opposite to the release layer of the film to prepare a support. The resin varnish 1 described above was uniformly applied to the release layer of this support so that the thickness of the resin composition layer after drying was 10 μm. Then, the resin varnish 1 was dried at 80°C to 100°C (average 90°C) for 2 minutes to obtain a resin sheet containing the support and the resin composition layer.

[0164] [Comparative Example 3] A PET film with a release layer (Lintec Corporation's "AL5", 38 μm thick) was prepared as a support. The resin varnish 3 was uniformly applied to the release layer of this support so that the thickness of the resin composition layer after drying was 10 μm. The resin varnish 3 was then dried at 80°C to 100°C (average 90°C) for 2 minutes to obtain a resin sheet containing the support and the resin composition layer.

[0165] [Preparation of samples for measurement and evaluation] (1) Surface preparation of the inner layer substrate A glass cloth substrate epoxy resin double-sided laminate (copper foil thickness 18 μm, substrate thickness 0.8 mm, Panasonic "R1515A") with an inner layer circuit was etched to 1 μm on both sides using MEC "CZ8100" to roughen the copper surface. Afterward, it was dried at 190°C for 30 minutes.

[0166] (2) Lamination of resin sheets The resin sheets obtained in the examples and comparative examples were laminated on both sides of an inner layer substrate using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd. 2-stage build-up laminator "CVP700") so that the resin composition layer was bonded to the inner layer substrate. Lamination was performed by reducing the pressure to 13 hPa or less for 30 seconds, followed by pressing at a temperature of 100°C and a pressure of 0.74 MPa for 30 seconds. Next, the laminated resin sheets were heat-pressed at atmospheric pressure, 100°C, and a pressure of 0.5 MPa for 60 seconds to smooth them. In this way, a laminate having a layer structure of support / resin composition layer / inner layer substrate / resin composition layer / support was obtained.

[0167] (3) Curing of the resin composition layer Next, the laminate, with the support still attached, was placed in a nitrogen oven. After placement, the door was closed and nitrogen was circulated until the oxygen concentration in the oven reached 0.5%. After confirming that the oxygen concentration in the oven had reached 0.5%, the resin composition layer was heat-cured under the following curing conditions. Specifically, the oven temperature was raised from 30°C to T1 (see Table 1; 130°C in Example 1) at a heating rate of 10°C / min, then held at T1 for 30 minutes, and then further raised to T2 (see Table 1; 175°C in Example 1) at a heating rate of 10°C / min, and held at T2 for 30 minutes. In this way, the resin composition layer was heat-cured to obtain a laminate having a layer structure of support / insulating layer / inner substrate / insulating layer / support. After that, the temperature was lowered to 30°C at a rate of 5°C / min and the laminate was removed from the nitrogen oven.

[0168] (4) Roughening treatment The support was peeled from the laminate to expose the insulating layer. Next, the laminate was immersed in a swelling solution (Atotec Japan's "Swelling Dip Securigant P," an aqueous solution of diethylene glycol monobutyl ether and sodium hydroxide) at 60°C for 10 minutes, then immersed in an oxidizing agent solution (Atotec Japan's "Concentrate Compact P," an aqueous solution with a potassium permanganate concentration of approximately 6% by mass and a sodium hydroxide concentration of approximately 4% by mass) at 80°C for 20 minutes, and finally immersed in a neutralizing solution (Atotec Japan's "Reduction Solution Securigant P," an aqueous sulfuric acid solution) at 40°C for 5 minutes. The resulting substrate is referred to as "Evaluation Substrate A."

[0169] <Measurement of arithmetic mean roughness Ra> For evaluation substrate A, the arithmetic mean roughness Ra was determined using a non-contact surface roughness meter (WYKO NT3300, manufactured by B-In Instruments) in VSI mode with a 50x lens, measuring a range of 121 μm × 92 μm. The measurement was performed by calculating the average of 10 randomly selected points.

[0170] <Measurement of adhesion (peel strength)> (1) Fabrication of evaluation board Evaluation substrate A was immersed in an electroless plating solution containing PdCl2 at 40°C for 5 minutes, and then immersed in an electroless copper plating solution at 25°C for 20 minutes. After annealing by heating at 150°C for 30 minutes, a plating resist was formed, and after pattern formation was created by etching the plating resist, copper sulfate electroplating was performed to form a conductive layer with a thickness of 30 μm. Next, annealing was performed at 200°C for 60 minutes. The resulting substrate is referred to as "evaluation substrate B".

[0171] (2) Measurement of peel strength A 10mm wide, 150mm long cut was made in the conductive layer of evaluation board B. One end of this cut was peeled off and grasped with a gripper (TSE Corporation's Autocom type testing machine "AC-50C-SL"). The load (kgf / cm) was measured when 100mm was peeled off vertically at a speed of 50mm / min at room temperature (25℃).

[0172] <Method for measuring water vapor permeability coefficient> The water vapor transmission coefficient of the support was determined by the following procedure. First, the water vapor transmission rate of the support (g / m³) was calculated. 2 The water vapor transmission rate (24h) was measured using a water vapor transmission rate measuring device (MOCON "PERMATRAN-W3 / 34") in accordance with JIS K7129, under conditions of 40°C and 90% relative humidity. The obtained water vapor transmission value was multiplied by the thickness of the support (mm) to obtain the water vapor transmission coefficient of the support (g / m²). 2 ·mm -1 The calculation (24 hours) was performed.

[0173] [Table 1]

Claims

1. (I) A step of laminating a resin sheet, which comprises a support and a resin composition layer provided on the support having an inorganic filler content of 60% by mass or more and a thickness of 15 μm or less, onto a substrate such that the resin composition layer is bonded to the substrate. (II) A step of forming an insulating layer by thermal curing the resin composition layer, (III) Step of peeling off the support, A method for manufacturing a circuit board, comprising the following in this order: The water vapor transmission coefficient of the support, calculated from the water vapor transmission rate of the support measured under conditions of 40°C and a relative humidity difference of 90% using a method compliant with JIS K7129, is 0.5 g / m². ２ mm －１ - Less than 24 hours, A method comprising, in step (II), subjecting the resin composition layer to a heat treatment in which it is held at a temperature T1, and then to a heat treatment in which it is held at a temperature T2 that is higher than the temperature T1.

2. The method according to claim 1, wherein the temperature T2 is 150°C or higher.

3. The method according to claim 1, wherein the difference between temperature T1 and temperature T2, T2-T1, is 20°C or more.

4. The method according to claim 1, wherein the temperature T1 is 50°C or higher.

5. The method according to claim 1, wherein in step (II), the resin composition layer is heated to a temperature T2 at a heating rate of 0.5°C / min or more and 30°C / min or less.

6. The method according to claim 1, wherein the resin composition layer comprises a thermosetting resin.

7. The method according to claim 1, wherein the resin composition layer comprises one or more curing agents selected from the group consisting of active ester curing agents, phenol curing agents, naphthol curing agents, and carbodiimide curing agents.

8. The method according to claim 1, further comprising the step of forming via holes in an insulating layer with a laser.

9. The method according to any one of claims 1 to 8, further comprising the step of forming a conductive layer on the surface of an insulating layer.

10. The method according to claim 9, wherein the peel strength between the insulating layer and the conductor layer is 0.3 kgf / cm or more.

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