Resin composition for circuit board formation, method for manufacturing the same, and use thereof

Abstract

To provide a resin composition for circuit board formation by which it is possible to obtain a cured material that is excellent in low dielectric constant and low dielectric loss tangent and is excellent in adhesion to copper foil.SOLUTION: A resin composition for circuit board formation of the invention includes hollow silica particles (A) and resin (B). Pressure at which it reaches a maximum value of pore volume measured by mercury intrusion method is 100 MPa or more in the hollow silica particles (A).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition for forming a circuit board, a method for producing the composition, and uses thereof. [Background technology]

[0002] In recent years, electronic devices such as tablets and smartphones have become increasingly sophisticated, resulting in dramatic increases in signal speed and operating frequency. As a result, electronic devices used in high-frequency ranges are required to have high low dielectric properties, and there is an increasing demand for low dielectric constants and low dielectric loss tangents.

[0003] Therefore, research and development of materials with low dielectric constants and low dielectric loss tangents is progressing. For example, Patent Document 1 discloses a resin composition containing an epoxy resin, a curing agent, hollow silica, and fused silica, the hollow silica and the fused silica being contained in predetermined amounts. This document states that the resin composition has a sufficiently small dielectric constant and dielectric loss tangent, and can sufficiently reduce the thermal expansion coefficient at 150°C or higher.

[0004] Patent Document 2 discloses a resin composition containing a thermosetting resin and a filler, the filler containing a predetermined number of bubbles and hollow particles having an average particle diameter of 0.01 to 10 μm. The document states that the resin composition can reduce the dielectric constant.

[0005] Patent Document 3 discloses a resin composition containing an epoxy resin, a predetermined curing agent, and hollow inorganic particles, the porosity and average particle size of which are within predetermined ranges. The document states that the resin composition can reduce the dielectric constant. The document also states that the resin composition can provide an insulating layer that can suppress blisters during reflow and has excellent process resistance. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-173841 [Patent Document 2] International Publication No. 2019 / 230661 [Patent Document 3] Japanese Patent Publication No. 2022-048225 [Patent Document 4] International Publication No. 2021 / 172294 [Patent Document 5] International Publication No. 2023 / 100676 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the conventional techniques described in Patent Documents 1 to 3 have room for improvement in terms of low dielectric constant and low dielectric loss tangent, as well as adhesion to copper foil. [Means for solving the problem]

[0008] The present inventors have discovered that by using specific hollow silica particles, a cured product can be obtained that has a low dielectric constant, a low dielectric loss tangent, and excellent adhesion to copper foil, and have completed the present invention. That is, the present invention can be shown as follows.

[0009] [1] Hollow silica particles (A), Resin (B); A resin composition for forming a circuit board, comprising: The resin composition for forming a circuit board, wherein the hollow silica particles (A) have a pressure at which the pore volume reaches a maximum value as measured by mercury intrusion porosimetry of 100 MPa or more. [2] The resin composition for forming circuit boards according to [1], wherein the weight loss rate of the hollow silica particles (A) calculated under the following measurement conditions is 5.0% or less. (Measurement conditions) Measurement equipment: TG-DTA (Thermogravimetry-Differential Thermal Analysis) Atmosphere: Air Measurement temperature: The temperature is raised from 30°C to 800°C at a rate of 10°C / min, and then held at 800°C for 30 minutes. [3] The resin composition for forming a circuit board according to [1] or [2], wherein the hollow silica particles (A) have a void ratio of 60% by volume or more and 90% by volume or less. [4] The resin composition for forming circuit boards according to any one of [1] to [3], wherein the hollow silica particles (A) have an average particle size of 0.1 μm or more and 3.0 μm or less. [5] The resin composition for forming circuit boards according to any one of [1] to [4], wherein the shell thickness of the hollow silica particles (A) is 0.01 μm or more and 0.20 μm or less. [6] The resin composition for forming circuit boards according to any one of [1] to [5], wherein the hollow silica particles (A) have a shell ratio of 1% or more and 50% or less. [7] The resin composition for forming a circuit board according to any one of [1] to [6], wherein the resin (B) comprises one or more resins selected from polyphenylene ether resins, maleimide resins, coumarone resins, polyether resins, styrene resins, cyanate resins, and epoxy resins. [8] The resin (B) contains an epoxy resin, The resin composition for forming a circuit board according to any one of [1] to [7], further comprising an active ester curing agent (C). [9] The resin composition for forming a circuit board according to [8], wherein the active ester curing agent (C) has a structure represented by the following general formula (1): [ka] In general formula (1), A is a substituted or unsubstituted arylene group linked via an aliphatic cyclic hydrocarbon group, Ar′ is a substituted or unsubstituted aryl group, B is a structure represented by the following general formula (B): [ka] (In general formula (B), Ar represents a substituted or unsubstituted arylene group; Y represents a single bond, a substituted or unsubstituted linear alkylene group having 1 to 6 carbon atoms, or a substituted or unsubstituted cyclic alkylene group having 3 to 6 carbon atoms, a substituted or unsubstituted divalent aromatic hydrocarbon group, an ether bond, a carbonyl group, a carbonyloxy group, a sulfide group, or a sulfone group; and n represents an integer of 0 to 4.) k is the average value of the repeating units and is in the range of 0.25 to 3.5.

[10] The resin composition for forming a circuit board according to any one of [1] to [9], further comprising silica particles (D) (excluding the hollow silica particles (A)).

[11] The resin composition for forming a circuit board according to any one of [1] to

[10] , A resin composition for forming a circuit board, wherein a cured product of the resin composition for forming a circuit board has a dielectric loss tangent Df of 0.0032 or less at 10 GHz.

[12] The resin composition for forming a circuit board according to any one of [1] to

[11] , The resin composition for forming a circuit board, wherein a cured product of the resin composition for forming a circuit board has a dielectric constant Dk of 1.8 or more and 2.8 or less at 10 GHz.

[13] The resin composition for forming a circuit board according to any one of [1] to

[12] , The resin composition for forming a circuit board has a linear expansion coefficient of 80 ppm / °C or more and 130 ppm / °C or less after curing.

[14] The resin composition for forming a circuit board according to any one of [1] to

[13] , A resin composition for forming a circuit board, wherein a cured product of the resin composition for forming a circuit board has a peel strength from copper foil of 0.3 kN / m or more.

[15] Hollow silica particles (A), Resin (B); A resin composition for forming a circuit board, comprising: The resin composition for forming a circuit board, wherein the weight loss rate of the hollow silica particles (A) calculated under the following measurement conditions is 5.0% or less. (Measurement conditions) Measurement equipment: TG-DTA (Thermogravimetry-Differential Thermal Analysis) Atmosphere: Air Measurement temperature: The temperature is raised from 30°C to 800°C at a rate of 10°C / min, and then held at 800°C for 30 minutes.

[16] A resin sheet made of the resin composition for forming a circuit board according to any one of [1] to

[15] .

[17] A carrier substrate; A resin film with a carrier, comprising: a resin sheet formed on the carrier base and made of the resin composition for forming a circuit board according to any one of [1] to

[15] .

[18] A prepreg obtained by impregnating a fiber base material with the resin composition for forming a circuit board according to any one of [1] to

[15] .

[19] A laminate comprising the prepreg according to

[18] above and a metal layer disposed on at least one surface thereof.

[20] A printed wiring board having an insulating layer made of a cured product of the resin composition for forming a circuit board according to any one of [1] to

[15] .

[21] The printed wiring board according to

[20] ; a semiconductor element mounted on a circuit layer of the printed wiring board or embedded in the printed wiring board.

[22] A wiring board comprising a conductor layer on a dielectric substrate made of a cured product of the resin composition for forming a circuit board according to any one of [1] to

[15] . [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a resin composition for forming circuit boards that can give a cured product that has a low dielectric constant, a low dielectric loss tangent, and excellent adhesion to copper foil. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view showing an example of the configuration of a resin film with a carrier in the present embodiment. [Figure 2]1A to 1C are cross-sectional views showing an example of a manufacturing process for a semiconductor device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described. In the present embodiment, for example, "1 to 10" represents "1 or more" to "10 or less" unless otherwise specified.

[0013] The resin composition for forming a circuit board of this embodiment (hereinafter, also referred to as "resin composition") contains hollow silica particles (A) and a resin (B).

[0014] [Hollow silica particles (A)] The hollow silica particles (A) have a pressure at which the pore volume reaches its maximum value as measured by mercury intrusion porosimetry of preferably 100 MPa or more, more preferably 110 MPa or more, and even more preferably 120 MPa or more. The upper limit is not particularly limited, but can be set to 800 MPa or less, preferably 500 MPa or less.

[0015] By mercury intrusion porosimetry, the shells of hollow silica particles are destroyed by injecting mercury, and the amount of mercury intrusion (pore volume) filling the interior of the particles and the pressure at that time can be measured. The pressure at which the pore volume becomes maximum can be used as an index of the strength of the hollow silica particles (A). In this embodiment, the hollow silica particles (A) have a pressure within the range at which the pore volume reaches a maximum value as measured by mercury porosimetry, and therefore have higher strength than conventional hollow silica particles. The hollow silica particles (A) can maintain their hollow structure against pressures, etc., applied when molding the resin composition for forming a circuit board of this embodiment, enabling the production of a cured product with a low dielectric constant and a low dielectric loss tangent. The use of the hollow silica particles (A) allows the production of a cured product with excellent product reliability and improved product yield.

[0016] In this embodiment, the measurement by mercury intrusion porosimetry can be performed in accordance with JIS-R1655 (2003), specifically, using a mercury porosimeter (manufactured by Micrometrics, product name: AutoPore IV 9600). Measurement can be performed under the following measurement conditions: pressure 50 mmHg, evacuation time 5 minutes, injection pressure 0.5 to 43,600 psi, and equilibration time 10 seconds.

[0017] The hollow silica particles (A) have a weight loss rate calculated under the following measurement conditions of 5.0% or less, preferably 4.0% or less, more preferably 3.0% or less, and even more preferably 2.5% or less. The lower limit is not particularly limited, but can be 0.5% or more, preferably 0.8% or more.

[0018] When the hollow silica particles (A) have a weight loss rate within the above range, a cured product having a low dielectric constant and a low dielectric loss tangent as well as excellent adhesion to copper foil can be obtained.

[0019] Since the hollow silica particles (A) have a lower weight loss rate than conventional hollow silica, it is presumed that they have fewer surface silanol groups and also fewer surface silanol groups inside the hollow (inner surface).The use of such hollow silica particles (A) is believed to provide excellent low dielectric constant and low dielectric loss tangent, and in particular to reduce the dielectric loss tangent. (Measurement conditions) Measurement equipment: TG-DTA (Thermogravimetry-Differential Thermal Analysis) Atmosphere: Air Measurement temperature: The temperature is raised from 30°C to 800°C at a rate of 10°C / min, and then held at 800°C for 30 minutes.

[0020] The hollow silica particles (A) may have a void ratio of preferably 60% by volume or more and 90% by volume or less, more preferably 65% ​​by volume or more and 85% by volume or less, and even more preferably 70% by volume or more and 82% by volume or less. When the hollow silica particles (A) have a void ratio within the above range, the particles have an excellent low dielectric constant and are well balanced with the mechanical strength.

[0021] Specifically, the hollow ratio of the hollow silica particles (A) is measured by the pycnometer method using argon gas and an Auto Pycnometer 1320 (Micromeritics) in accordance with JIS-R-1620 (1995). The hollow ratio (%) can then be calculated using the density ρ (density of silica constituting the hollow silica particles (A)) according to the formula: [1-(ρ / ρ)]×100.

[0022] The hollow silica particles (A) may have an average particle size (median size) of preferably 0.1 μm or more and 3.0 μm or less, more preferably 0.2 μm or more and 2.5 μm or less, and even more preferably 0.3 μm or more and 2.0 μm or less.

[0023] When the average particle size of the hollow silica particles (A) is within the above range, the resin composition for forming a circuit board of this embodiment has excellent handleability and dispersibility when prepared, and also has excellent mechanical strength. The average particle size (median size) of the hollow silica particles (A) can be measured, for example, using a laser diffraction / scattering particle size distribution measuring device.

[0024] Furthermore, the shell thickness of the hollow silica particles (A) can be preferably 0.01 μm or more and 0.20 μm or less, more preferably 0.15 μm or more and 0.15 μm or less, and even more preferably 0.02 μm or more and 0.10 μm or less. When the hollow silica particles (A) having an average particle size in the above range have the above shell ratio, the proportion of hollows is large, resulting in an excellent low dielectric constant.

[0025] Specifically, the shell thickness of the hollow silica particles (A) can be calculated by the following formula. Formula: [Volume average particle diameter (outer diameter of hollow silica particles (A)) - Hollow diameter (inner diameter of hollow silica particles (A))] / 2 The hollow diameter is calculated by the following formula: 4 / 3π×(R / 2) using the volume average particle diameter R of the hollow particles and the porosity (the hollowness (%) / 100). 3 ×Porosity=4 / 3π×(r / 2) 3 The inner diameter r of the hollow particle can be calculated using the formula:

[0026] The shell ratio of the hollow silica particles (A) can be set to preferably 1% or more and 50% or less, more preferably 3% or more and 30% or less, and even more preferably 5% or more and 20% or less. Specifically, the shell ratio of the hollow silica particles (A) can be calculated from the volume average particle diameter R of the hollow particles and the inner diameter r of the hollow particles by the formula: shell ratio (%)=(r / R)×100.

[0027] The content of the hollow silica particles (A) is preferably 2 to 60 mass %, more preferably 3 to 50 mass %, and even more preferably 5 to 30 mass %, based on the total solid mass of the resin composition. The content of the hollow silica particles (A) is preferably 3 to 70% by volume, more preferably 5 to 60% by volume, and even more preferably 5 to 50% by volume, based on the total solid volume of the resin composition.

[0028] By setting the content of the hollow silica particles (A) within the above range, it is possible to obtain a cured product with excellent low dielectric constant and low dielectric loss tangent, particularly low dielectric loss tangent, and excellent adhesion to copper foil, resulting in excellent product reliability.

[0029] (Method for producing hollow silica particles (A)) To produce the hollow silica particles (A) of this embodiment, first, a hollow silica particle (A) precursor is produced by a template method using a template or a template-free method not using a template. In this embodiment, the template method using a mold is preferred because it is superior in controllability of particle shape and also makes it easy to control the shell thickness, the hollow shape inside the shell, and the like.

[0030] Examples of the template method include an organic particle template method, an inorganic particle template method, a biological particle template method, an emulsion template method, and a gas particle template method. In the present embodiment, the hollow silica particle (A) precursor can be produced by the emulsion template method.

[0031] In this embodiment, examples of a method for producing hollow silica particle (A) precursors by the emulsion template method include a method in which an O / W (oil-in-water) emulsion containing an aqueous phase, an oil phase, and a surfactant is used to prepare oil-silica composite particles encapsulating an oil phase (oil droplets) in the emulsion, and then the oil is removed from the oil-silica composite particles.

[0032] The oil phase may be a water-insoluble organic solvent. Examples of the water-insoluble organic solvent include, but are not limited to, hydrocarbon solvents. Examples of the hydrocarbon solvent include aliphatic hydrocarbon solvents and aromatic hydrocarbon solvents. Examples of the aliphatic hydrocarbon solvent include hexane, cyclohexane, pentane, heptane, octane, nonane, decane, and dodecane. Examples of aromatic hydrocarbon solvents include benzene, toluene, xylene, ethylbenzene, propylbenzene, and isopropylbenzene. As the surfactant, it is preferable to use a nonionic surfactant from the viewpoint of emulsifying properties, as the use of a nonionic surfactant provides excellent emulsion stability of the oil phase (oil droplets) in water.

[0033] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene sorbitan fatty acid esters, sorbitan fatty acid esters, polyoxysorbitan fatty acid esters, polyoxyethylene alkylamines, glycerin fatty acid esters, and oxyethylene-oxypropylene block copolymers. In addition to the nonionic surfactant, a cationic surfactant, an anionic surfactant, or an amphoteric surfactant can also be used.

[0034] First, the above ingredients are added to water and mixed and stirred to prepare an O / W emulsion. The amounts of the water-insoluble organic solvent and surfactant can be determined based on their type and emulsifying power. The method of mixing and stirring is not particularly limited and can be determined using known methods taking into account the size of the oil droplets in the emulsion.

[0035] Next, oil-silica composite particles encapsulating the oil phase (oil droplets) are prepared in an O / W emulsion. Specifically, by adding a silanol precursor and an alkaline substance to an O / W emulsion, the surface of the oil droplets is coated with the silanol precursor, which is then hydrolyzed to form silanols, which are then dehydrated and condensed to produce oil-silica composite particles. In this step, the amounts of the silanol precursor and alkaline substance added are appropriately selected depending on their types, and the temperature in this step is appropriately adjusted depending on the types and amounts of the silanol precursor and alkaline substance.

[0036] The silanol precursor is a compound that generates a silanol compound by hydrolysis of an alkoxysilane or the like, and preferred examples include alkyl orthosilicate esters and alkyl pyrosilicate esters. The alkaline substance is preferably a hydroxide salt of quaternary ammonium. Specific examples of the hydroxide salt of quaternary ammonium include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tributylmethylammonium hydroxide, trimethylhydroxyethylammonium hydroxide (choline), tetraethanolammonium hydroxide, methyltriethanolammonium hydroxide, and dimethylbis(2-hydroxyethyl)ammonium hydroxide.

[0037] Next, the oil (oil droplets) present in the core of these oil-silica composite particles are removed to obtain hollow silica particle (A) precursors. Specifically, the oil (oil droplets) are removed by heat treatment at a temperature of 300°C or higher. In addition, in order to remove silanol groups present on the surface of the hollow silica particle (A) precursor, it is also preferable to calcinate the precursor at 800° C. or higher. By reducing the surface silanol groups of the precursor, the dielectric loss tangent can be reduced.

[0038] The calcined hollow silica particle (A) precursor is then surface-treated with an organosilicon compound to obtain hollow silica particles (A). The silanol groups present on the surface of the calcined hollow silica particle (A) precursor react with the organosilicon compound, reducing the surface silanol groups of the precursor, thereby reducing the dielectric loss tangent. Furthermore, the resulting cured product exhibits improved adhesion to copper foil and superior peel strength.

[0039] Examples of the organosilicon compound include silazane compounds such as hexamethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, octamethyltrisilazane, and hexamethylcyclotrisilazane; aminosilanes such as trimethylsilyldimethylamine and trimethylsilyldiethylamine; chlorosilanes such as trimethylchlorosilane; alkoxysilanes such as trimethylmethoxysilane and trimethylethoxysilane; and cyclic siloxane compounds such as hexamethylcyclotrisiloxane and octamethylcyclotetrasiloxane. Silazane compounds are preferred because of their excellent silylation effect, with hexaorganodisilazane compounds being more preferred and hexamethyldisilazane being particularly preferred. Silazane compounds may be used alone or in combination of two or more.

[0040] The amount of the organosilicon compound to be used in the treatment of the calcined hollow silica particle (A) precursor is not particularly limited as long as the effects of the present invention are achieved, but it is sufficient that the amount is 0.5 parts by mass or more, and preferably 1 part by mass or more, per 100 parts by mass of the precursor. The upper limit is also not particularly limited, but is preferably 15 parts by mass or less.

[0041] Examples of the surface treatment method include a dry method in which the organosilicon compound is sprayed onto the precursor of the calcined hollow silica particles (A), and a wet method in which the precursor of the calcined hollow silica particles (A) is dispersed in a predetermined solvent, and then the organosilicon compound is added to cause a reaction.

[0042] [Resin (B)] As the resin (B), any known resin for forming circuit boards can be used as long as the effects of the present invention are achieved.

[0043] The resin (B) preferably includes polyphenylene ether resin, maleimide resin, coumarone resin, polyether resin, styrene resin, cyanate resin, epoxy resin, etc., and one or more types selected from these may be contained.

[0044] (Polyphenylene ether resin) In this embodiment, a modified polyphenylene ether resin can be preferably used as the polyphenylene ether resin. The modified polyphenylene ether resin is a modified polyphenylene ether, and for example, those described in paragraphs 0018 to 0061 of WO 2014 / 203511 can be used. More specifically, they are as follows.

[0045] The modified polyphenylene ether resin according to this embodiment is not particularly limited, but is preferably a modified polyphenylene ether whose terminals are modified with a substituent having a carbon-carbon unsaturated bond. The substituent having a carbon-carbon unsaturated bond is not particularly limited, but examples thereof include substituents represented by the following formula (f-1).

[0046] [ka]

[0047] In the above formula (f-1), n ​​represents an integer of 0 to 10, Z represents an arylene group, and R 1 ~R 3 are independently a hydrogen atom or an alkyl group.

[0048] In the above formula (f-1), when n = 0, Z is directly bonded to the terminal of the polyphenylene ether resin. Examples of the arylene group of Z include monocyclic aromatic groups such as a phenylene group and polycyclic aromatic groups such as a naphthalene ring, and also include derivatives in which a hydrogen atom bonded to the aromatic ring is substituted with a functional group such as an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group.

[0049] Examples of the functional group represented by the formula (f-1) include a functional group containing a vinylbenzyl group. More specifically, examples include at least one substituent selected from the following formula (f-2) or formula (f-3):

[0050] [ka]

[0051] [ka]

[0052] Furthermore, examples of other substituents having a carbon-carbon unsaturated bond directly bonded to the terminal of the polyphenylene ether resin include (meth)acrylate groups represented by the following formula (f-4).

[0053] [ka]

[0054] In the above formula (f-4), R 4 represents a hydrogen atom or an alkyl group. The alkyl group is preferably an alkyl group having 1 to 3 carbon atoms.

[0055] The modified polyphenylene ether resin of the present embodiment preferably has a hydroxy group, a methacrylic group, or a styrene group at both ends, from the viewpoint of achieving both low dielectric properties and good impregnation properties.

[0056] Furthermore, the polyphenylene ether resin in the modified polyphenylene ether resin of this embodiment has a polyphenylene ether chain in the molecule, and preferably has, for example, a repeating unit represented by the following formula (f-5) in the molecule.

[0057] [ka]

[0058] In the above formula (f-5), m represents 1 to 50. 5 , R 6 , R 7 and R 8 are each independently selected from the group consisting of the same or different groups. 5 , R 6 , R 7 and R 8 represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group. Among these, a hydrogen atom and an alkyl group are preferred.

[0059] The alkyl group is not particularly limited, but is preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms. More specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group.

[0060] The alkenyl group is not particularly limited, but is preferably an alkenyl group having 2 to 18 carbon atoms, more preferably an alkenyl group having 2 to 10 carbon atoms. More specific examples include a vinyl group, an allyl group, and a 3-butenyl group.

[0061] The alkynyl group is not particularly limited, but for example, an alkynyl group having 2 to 18 carbon atoms is preferred, and an alkynyl group having 2 to 10 carbon atoms is more preferred. More specific examples include an ethynyl group and a prop-2-yn-1-yl group (propargyl group).

[0062] The alkylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkyl group, but for example, an alkylcarbonyl group having 2 to 18 carbon atoms is preferred, and an alkylcarbonyl group having 2 to 10 carbon atoms is more preferred. More specific examples include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a pivaloyl group, a hexanoyl group, an octanoyl group, and a cyclohexylcarbonyl group.

[0063] The alkenylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkenyl group, but for example, an alkenylcarbonyl group having 3 to 18 carbon atoms is preferred, and an alkenylcarbonyl group having 3 to 10 carbon atoms is more preferred. More specific examples include an acryloyl group, a methacryloyl group, and a crotonoyl group.

[0064] The alkynylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkynyl group, but for example, an alkynylcarbonyl group having 3 to 18 carbon atoms is preferred, and an alkynylcarbonyl group having 3 to 10 carbon atoms is more preferred. More specific examples include a propioloyl group.

[0065] The method for synthesizing the modified polyphenylene ether resin according to the present embodiment is not particularly limited as long as it can synthesize a modified polyphenylene ether resin whose terminals are modified with substituents having carbon-carbon unsaturated bonds. For example, a method can be exemplified in which a polyphenylene ether resin in which the hydrogen atoms of the terminal phenolic hydroxyl groups are substituted with alkali metal atoms such as sodium or potassium is reacted with a compound represented by the following formula (f-6):

[0066] [ka]

[0067] In the formula (f-6), similarly to the formula (1), n ​​represents an integer of 0 to 10, Z represents an arylene group, and R 1 ~R 3 are independently a hydrogen atom or an alkyl group. X is a halogen atom, and specific examples thereof include a chlorine atom, a bromine atom, an iodine atom, and a fluorine atom. Among these, a chlorine atom is preferred. The compound represented by the formula (f-6) is not particularly limited, but is preferably, for example, p-chloromethylstyrene or m-chloromethylstyrene. In addition, the compounds represented by the formula (f-6) may be used alone or in combination of two or more of the above-mentioned compounds.

[0068] The polyphenylene ether resin used as the raw material is not particularly limited as long as it can ultimately synthesize a predetermined modified polyphenylene ether resin. Specific examples include polyarylene ether copolymers composed of 2,6-dimethylphenol and at least one of a bifunctional phenol and a trifunctional phenol, and those containing polyphenylene ether as the main component, such as poly(2,6-dimethyl-1,4-phenylene oxide). More specific examples of such polyphenylene ether resins include polyphenylene ether resins having the structure shown in the following formula (f-7).

[0069] [ka]

[0070] In the above formula (f-7), for example, the sum of s and t is preferably 1 to 30. Furthermore, s is preferably 0 to 20, and t is preferably 0 to 20. That is, s is preferably 0 to 20, t is preferably 0 to 20, and the sum of s and t is preferably 1 to 30. As the modified polyphenylene ether resin, it is preferable to use, for example, a resin having a structure shown in the following formula (f-8).

[0071] [ka]

[0072] In the above formula (f-8), s and t are the same as those in the above formula (f-7), and R 4 has the same meaning as the above formula (f-4).

[0073] Commercially available modified polyphenylene ether resins in which the terminal hydroxyl groups of the polyphenylene ether resin of the above formula (f-8) have been modified with methacrylic groups include "SA9000" manufactured by SABIC Innovative Plastics.

[0074] In the present embodiment, the mass average molecular weight of the polyphenylene ether resin is preferably 500 or more and 5,000 or less, more preferably 800 or more and 4,000 or less, and even more preferably 1,000 or more and 3,000 or less.

[0075] The mass average molecular weight may be measured by a general molecular weight measurement method, and specifically, may be a value measured using gel permeation chromatography (GPC).

[0076] By setting the mass average molecular weight of the polyphenylene ether resin to be equal to or greater than the above lower limit, the excellent dielectric properties of the polyphenylene ether resin are exhibited, and the cured product thereof further exhibits excellent adhesion and heat resistance. When a modified polyphenylene ether resin is used as the polyphenylene ether resin of this embodiment, the modified polyphenylene ether resin is modified and therefore has terminal reactive groups, particularly terminal unsaturated double bonds, so that it is thought that the cured product has an improved glass transition temperature while maintaining low dielectric properties, good impregnation properties, and sufficiently high heat resistance and adhesion. On the other hand, by adjusting the mass average molecular weight of the polyphenylene ether resin to the above upper limit or less, the moldability, solvent solubility and storage stability become good.

[0077] The content of the polyphenylene ether resin is preferably 0.1 to 30 mass %, more preferably 0.2 to 20 mass %, and even more preferably 0.3 to 15 mass %, based on the total solid mass of the resin composition.

[0078] By setting the content of the polyphenylene ether resin to the above lower limit or more, a low dielectric loss tangent can be obtained, while by setting the content of the polyphenylene ether resin to the above upper limit or less, an increase in viscosity can be suppressed and good impregnation properties can be obtained.

[0079] (maleimide resin) The maleimide resin of this embodiment has a bicyclic hydrocarbon group. The bicyclic hydrocarbon group refers to a residue obtained by removing one hydrogen atom from a bicyclic hydrocarbon formed of 8 to 10 carbon atoms. Specific examples include a naphthalene ring group, a dihydronaphthalene ring group, a tetrahydronaphthalene ring group, an octatetrahydronaphthalene ring group, an indene ring group, an indane ring group, and an azulene ring group. Among these, an indane ring group is preferred in terms of reducing viscosity. Examples of maleimide resins having an indane ring group include those represented by the following formula (a-1).

[0080] [ka]

[0081] (In formula (a-1), Ra and Rb each independently represent any one of an alkyl group, an alkyloxy group, and an alkylthio group having 1 to 10 carbon atoms, an aryl group, an aryloxy group, and an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxyl group, and a mercapto group. q represents an integer value of 0 to 4, and r represents an integer value of 0 to 3. n represents the average number of repeating units of 0.5 to 20.)

[0082] In formula (a-1), when q is 2 to 4, Ra may be the same or different in the same ring, and when r is 2 to 3, Rb may be the same or different in the same ring.

[0083] In formula (a-1), Ra is preferably an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms. This reduces the planarity near the maleimide group and decreases the crystallinity while maintaining the good reactivity of the maleimide group, thereby improving solubility in solvents. Furthermore, q is preferably 2 to 3, and more preferably 2.

[0084] In formula (a-1), when r is 0, Rb is preferably a hydrogen atom, which reduces steric hindrance during the formation of the indane skeleton in the maleimide, allowing for stable synthesis of the maleimide.

[0085] Furthermore, when r is 1 to 3, Rb is preferably at least one selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and an aryl group having 6 to 10 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms. The maleimide resin of the present embodiment has an indane skeleton in its structure, and thus can have improved solvent solubility compared to conventional maleimide compounds.

[0086] The average number n (average value) of repeating units in the indane skeleton of formula (a-1) is preferably 0.5 to 20, more preferably 0.7 to 10.0, even more preferably 0.95 to 10.0, particularly preferably 0.98 to 9.0, even more preferably 0.99 to 8.0, even more preferably 1.0 to 7.0, and even more preferably 1.0 to 6.0. By making the repeating unit n equal to or greater than the lower limit, the proportion of high molecular weight components increases, and the cured product can be made brittle-resistant and heat-resistant.

[0087] On the other hand, by setting the repeating unit n to the above upper limit or less, the proportion of high molecular weight components is reduced, which improves solvent solubility and also provides good flowability and handleability.

[0088] Furthermore, the maleimide group in the maleimide resin has a five-membered ring planar structure, and the double bond of the maleimide group is highly polar and prone to intermolecular interactions, so that it exhibits strong intermolecular interactions with the maleimide group, benzene ring, other compounds having a planar structure, etc., and can suppress molecular motion. Therefore, by including the maleimide resin in the resin composition of this embodiment, the linear expansion coefficient of the resulting insulating layer can be reduced, the glass transition temperature can be increased, and further, the heat resistance can be improved.

[0089] The content of the maleimide resin is preferably 1 part by mass or more and 40 parts by mass or less, more preferably 2 parts by mass or more and 35 parts by mass or less, and even more preferably 4 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the total solid content of the resin composition.

[0090] By setting the content of the maleimide resin at or above the lower limit, it is possible to lower the viscosity and improve the impregnation property while maintaining a good and low dielectric loss tangent, and also to lower the linear expansion coefficient, increase the glass transition temperature, and improve the heat resistance. On the other hand, by setting the content of the maleimide resin to the above upper limit or less, it is possible to improve the balance between a good dielectric loss tangent, a low dielectric loss tangent, and impregnation properties.

[0091] (coumarone resin) The coumarone resin of this embodiment refers to a (co)polymer containing a coumarone residue in its skeleton structure and having an average degree of polymerization of 4 to 8, and may be a coumarone (1-benzofuran) polymer, or a copolymer with indene (CH), styrene (CH), α-methylstyrene, methylindene, or vinyltoluene. Of these, a coumarone-indene copolymer and a coumarone-indene-styrene copolymer are preferred.

[0092] That is, the coumarone resin contains structural units derived from coumarone monomers, and may also contain structural units derived from indene monomers and structural units derived from other monomers. Examples of structural units derived from other monomers include structural units derived from styrene monomers. The coumarone resin may have a repeating structure of these structural units. Examples of the structural unit derived from the indene-based monomer include those represented by the following general formula (M1).

[0093] [ka] In general formula (M1), R 1 From R 7 are each independently hydrogen or an organic group having 1 to 3 carbon atoms. Examples of the structural unit derived from the coumarone monomer include those represented by the following general formula (M2).

[0094] [ka] In general formula (M2), R C is hydrogen or an organic group having 1 to 3 carbon atoms. C may be the same as each other or different from each other. Examples of the structural unit derived from the styrene-based monomer include those represented by the following general formula (M3).

[0095] [ka]

[0096] In general formula (M3), R S is hydrogen or an organic group having 1 to 3 carbon atoms. S may be the same as each other or different from each other. In the above general formulas (M1) to (M3), R 1 From R 7 , R C and R S For example, the structure of the organic group may include atoms other than hydrogen and carbon.

[0097] Specific examples of atoms other than hydrogen and carbon include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, fluorine atoms, chlorine atoms, etc. The atoms other than hydrogen and carbon may include one or more of the above specific examples.

[0098] In the above general formulas (M1) to (M3), R 1 From R 7 , R C and R S are each independently, for example, hydrogen or an organic group having 1 to 3 carbon atoms, preferably hydrogen or an organic group having 1 carbon atom, and more preferably hydrogen.

[0099] In the above general formulae (M1) to (M3), the R 1 From R 7 , R C and R SSpecific examples of the organic group constituting the formula (I) include alkyl groups such as methyl, ethyl, and n-propyl groups; alkenyl groups such as allyl and vinyl groups; alkynyl groups such as ethynyl groups; alkylidene groups such as methylidene and ethylidene groups; cycloalkyl groups such as cyclopropyl groups; and heterocyclic groups such as epoxy and oxetanyl groups.

[0100] The coumarone resin may contain, among others, a copolymer of indene, coumarone and styrene, or a copolymer of indene and styrene, which can improve low dielectric properties. Furthermore, the coumarone resin has reactive groups such as OH groups and COOH groups, which can improve the low dielectric properties. The coumarone resin may have an aromatic structure having a phenolic hydroxyl group inside or at the end.

[0101] The upper limit of the mass average molecular weight Mw of the coumarone resin is, for example, preferably not more than 4000, more preferably not more than 2000, even more preferably not more than 1500, and even more preferably not more than 1200. This improves the compatibility of the coumarone resin with other resins, allowing the coumarone resin to be appropriately dispersed.

[0102] On the other hand, the lower limit of the mass average molecular weight Mw of the coumarone resin is, for example, preferably at least 400, more preferably at least 500, even more preferably at least 550, and even more preferably at least 600. This allows the coumarone resin to be appropriately dispersed in the resin composition.

[0103] The lower limit of the coumarone resin content is, for example, 0.1 parts by mass or more, preferably 0.2 parts by mass or more, and more preferably 0.4 parts by mass or more, relative to 100 parts by mass of the total solid content of the resin composition, thereby achieving a good balance between low dielectric properties and impregnation properties while improving low water absorption properties.

[0104] On the other hand, the upper limit of the coumarone resin content is, for example, 20 parts by mass or less, preferably 15 parts by mass or less, and more preferably 12 parts by mass or less, relative to 100 parts by mass of the total solid content of the resin composition, which allows for a good balance with other physical properties such as moldability and heat resistance. The melting point of the coumarone resin is preferably 40°C to 120°C, and can be controlled by the molecular weight and degree of polymerization.

[0105] (Polyether resin) As the polyether resin of this embodiment, a resin represented by the following general formula (i) can be used. TIFF2025151557000015.tif38153

[0106] In the general formula (i), X 1 represents an alkyl group having 1 to 5 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. 1 may be the same or different. k represents an integer of 1 to 10, preferably an integer of 1 to 5, and more preferably an integer of 1 to 3. X 2 Each of X independently represents an alkyl group having 1 to 5 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. 1 may be the same or different. 1 represents an integer of 0 to 5, preferably an integer of 0 to 3, and more preferably 0. X 3 represents a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group, and is preferably a linear or branched alkyl group having 1 to 12 carbon atoms, and more preferably a linear or branched alkyl group having 5 to 10 carbon atoms. m represents the average number of repeating units of 1 to 10. n represents the average number of repeating units of 1 to 10. By using a polyether resin having this structure, the dielectric loss tangent is excellent.

[0107] In this embodiment, the mass average molecular weight of the polyether resin is preferably 200 or more and 10,000 or less, more preferably 300 or more and 7,000 or less, and even more preferably 400 or more and 5,000 or less.

[0108] The mass average molecular weight may be measured by a general molecular weight measurement method, and specifically, may be a value measured using gel permeation chromatography (GPC).

[0109] By setting the mass average molecular weight of the polyether resin to the above lower limit or more, the excellent dielectric properties of the polyether resin are exhibited, and the cured product thereof can have excellent adhesion and heat resistance. On the other hand, by setting the mass average molecular weight of the polyether resin to the above upper limit or less, the moldability, solvent solubility, and storage stability can be improved.

[0110] The content of the polyether resin is preferably 0.1 to 30 mass %, more preferably 0.2 to 20 mass %, and even more preferably 0.3 to 15 mass %, based on the total solid mass of the resin composition.

[0111] By setting the content of the polyether resin to the above lower limit or more, a low dielectric loss tangent can be obtained, while by setting the content of the polyether resin to the above upper limit or less, an increase in viscosity can be suppressed and good impregnation properties can be obtained.

[0112] (styrene resin) As the styrene resin of this embodiment, a resin represented by the following general formula (i) can be used. TIFF2025151557000016.tif34153

[0113] In the general formula (i), R 1 and R 2 may be the same or different and represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom. Q represents a linear or branched alkylene group having 2 to 6 carbon atoms, which may contain a double bond in the structure.

[0114] a represents an average number of repeating units of 5 to 50, b represents an average number of repeating units of 5 to 50, and c represents an average number of repeating units of 5 to 50. By using a styrene resin having this structure, the dielectric loss tangent is excellent.

[0115] In this embodiment, the mass average molecular weight of the styrene resin is preferably 1,000 or more and 20,000 or less, more preferably 2,000 or more and 15,000 or less, and even more preferably 4,000 or more and 10,000 or less.

[0116] The mass average molecular weight may be measured by a general molecular weight measurement method, and specifically, may be a value measured using gel permeation chromatography (GPC).

[0117] By setting the mass average molecular weight of the styrene resin to the above lower limit or more, the excellent dielectric properties of the styrene resin are exhibited, and the cured product thereof can be obtained as a resin composition having excellent adhesion and heat resistance. On the other hand, by setting the mass average molecular weight of the styrene resin to the above upper limit or less, the moldability, solvent solubility, and storage stability can be improved.

[0118] The content of the styrene resin is preferably 0.1 to 40 mass %, more preferably 0.2 to 30 mass %, and even more preferably 0.3 to 25 mass %, based on the total solid mass of the resin composition.

[0119] By setting the content of the styrene resin to the above lower limit or more, a low dielectric loss tangent can be obtained, while by setting the content of the styrene resin to the above upper limit or less, an increase in viscosity can be suppressed and good impregnation properties can be obtained.

[0120] [Cyanate resin] The cyanate resin makes it easier to obtain a low coefficient of thermal expansion, a low dielectric constant, and a low dielectric loss tangent. It also improves peel strength and heat resistance.

[0121] The cyanate resin is preferably an aromatic cyanate resin, and specific examples thereof include novolac cyanate resins such as phenol novolac and cresol novolac; aralkyl cyanate resins such as phenyl aralkyl, biphenyl aralkyl, and naphthalene aralkyl; and bisphenol cyanate resins such as bisphenol A cyanate resin, bisphenol E cyanate resin, and tetramethyl bisphenol F cyanate resin.

[0122] Among these, bisphenol-type cyanate and / or novolac-type cyanate resins are preferred, and a combination of both is even more preferred. The reason for this is that bisphenol-type cyanate ester resins have fewer crosslinking points, so when triazine rings are formed, unreacted cyanate groups are less likely to remain, making it easier to maintain good dielectric properties. Furthermore, novolac-type cyanate resins form triazine rings after the curing reaction, which improves rigidity and heat resistance and makes them easier to accommodate miniaturization and higher frequencies. As the novolac type cyanate resin, for example, one represented by the following formula (I) can be used.

[0123] [ka]

[0124] The average repeating unit number n of the novolac cyanate resin represented by general formula (I) is any integer. The average repeating unit number n is not particularly limited, but is preferably 1 or more, more preferably 2 or more. When the average repeating unit number n is equal to or greater than the above-mentioned lower limit, the heat resistance of the novolac cyanate resin is improved, and elimination and volatilization of oligomers during heating can be suppressed. Furthermore, the average repeating unit number n is not particularly limited, but is preferably 10 or less, more preferably 7 or less. When n is equal to or less than the above-mentioned upper limit, an increase in melt viscosity can be suppressed, and the moldability of the prepreg can be improved.

[0125] The cyanate resin may also be modified, for example, it may contain butadiene-modified cyanate modified with butadiene. Specifically, the butadiene-modified cyanate may be obtained by mixing a cyanate ester compound with polybutadiene and then thermally polymerizing the mixture, and / or by mixing a polymer of a cyanate ester compound with polybutadiene and then thermally polymerizing the mixture. This allows for good heat resistance while achieving both good dielectric properties and low warpage.

[0126] Although there are no particular limitations on the lower limit of the weight-average molecular weight (Mw) of the cyanate resin, Mw is preferably at least 500, and more preferably at least 600. When Mw is at least the above lower limit, the occurrence of tackiness can be suppressed when a prepreg is produced, and the prepregs can be prevented from adhering to each other when they come into contact with each other, or from transferring.

[0127] Furthermore, the upper limit of Mw is not particularly limited, but is preferably not more than 4,500, more preferably not more than 3,000. When Mw is not more than the upper limit, the cyclization reaction of the cyanate resin (C) can be prevented from accelerating, and defects in the insulating layer and a decrease in the peel strength between the insulating layer and the metal layer can be prevented. The Mw of the cyanate resin can be measured, for example, by GPC (gel permeation chromatography, standard substance: polystyrene equivalent).

[0128] Furthermore, one type of cyanate resin may be used alone, or two or more types having different Mw may be used in combination, or one or more types may be used in combination with their prepolymers.

[0129] In this embodiment, the content of the cyanate resin is preferably 7% by mass or more, more preferably 10% by mass or more, and even more preferably 12% by mass or more, based on the total solid mass of the resin composition for forming a circuit board of this embodiment.

[0130] On the other hand, the content of the cyanate resin is preferably 30% by mass or less, more preferably 27% by mass or less, and even more preferably 25% by mass or less, based on the total solid mass of the resin composition for forming a circuit board of this embodiment.

[0131] [Epoxy resin] The epoxy resin may be any monomer, oligomer, or polymer having two or more epoxy groups in one molecule, and there are no limitations on the molecular weight or molecular structure.

[0132] Examples of epoxy resins include biphenyl-type epoxy resins; bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and tetramethylbisphenol F-type epoxy resins; stilbene-type epoxy resins; novolac-type epoxy resins such as phenol novolac-type epoxy resins and cresol novolac-type epoxy resins; polyfunctional epoxy resins such as trisphenol-type epoxy resins exemplified by triphenolmethane-type epoxy resins and alkyl-modified triphenolmethane-type epoxy resins; phenol aralkyl-type epoxy resins having a phenylene skeleton; naphthol aralkyl-type epoxy resins having a phenylene skeleton; the epoxy resins may include one or more selected from the group consisting of phenol aralkyl epoxy resins such as phenol aralkyl epoxy resins having a biphenylene skeleton and naphthol aralkyl epoxy resins having a biphenylene skeleton; naphthol epoxy resins such as dihydroxynaphthalene epoxy resins and epoxy resins obtained by glycidyl etherifying a dihydroxynaphthalene dimer; triazine nucleus-containing epoxy resins such as triglycidyl isocyanurate and monoallyl diglycidyl isocyanurate; and bridged cyclic hydrocarbon compound-modified phenolic epoxy resins such as dicyclopentadiene-modified phenolic epoxy resins.

[0133] Of these, novolac epoxy resins, polyfunctional epoxy resins, and phenol aralkyl epoxy resins are preferably used from the viewpoint of the effects of the present invention. Also, from the same viewpoint, the epoxy resin preferably contains one or more selected from the group consisting of orthocresol novolac epoxy resins, phenol aralkyl epoxy resins having a biphenylene skeleton, and triphenylmethane epoxy resins, and more preferably contains one or more selected from the group consisting of orthocresol novolac epoxy resins and phenol aralkyl epoxy resins having a biphenylene skeleton.

[0134] The epoxy resin may be contained in an amount of preferably 3 to 50 mass %, more preferably 5 to 40 mass %, and even more preferably 10 to 35 mass %, based on the total solids mass of the resin composition for forming a circuit board of this embodiment. By setting the content of the epoxy resin to be equal to or greater than the above-mentioned lower limit, a low dielectric loss tangent can be obtained. On the other hand, by setting the content of the epoxy resin to be equal to or less than the above-mentioned upper limit, an increase in viscosity can be suppressed, and good impregnation properties can be obtained.

[0135] When the resin (B) contains an epoxy resin, it is preferable to use an active ester curing agent (C).

[0136] [Active ester curing agent (C)] The active ester curing agent (C) may be a compound having one or more active ester groups in one molecule. Among them, preferred active ester curing agents (C) are 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.

[0137] Preferred examples of the active ester curing agent (C) include active ester curing agents containing a dicyclopentadiene-type diphenol structure, active ester curing agents containing a naphthalene structure, active ester curing agents containing an acetylated product of phenol novolac, and active ester curing agents containing a benzoylated product of phenol novolac, and at least one of these may be used. Among these, active ester curing agents containing a naphthalene structure and active ester curing agents containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

[0138] In this embodiment, the active ester curing agent (C) may be, for example, a resin having a structure represented by the following general formula (1).

[0139] [ka]

[0140] In general formula (1), "B" is a structure represented by general formula (B).

[0141] [ka]

[0142] In general formula (B), Ar is a substituted or unsubstituted arylene group. Examples of the substituent of the substituted arylene group include an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, and an aralkyl group.

[0143] Y is a single bond, a substituted or unsubstituted linear alkylene group having 1 to 6 carbon atoms, a substituted or unsubstituted cyclic alkylene group having 3 to 6 carbon atoms, a substituted or unsubstituted divalent aromatic hydrocarbon group, an ether bond, a carbonyl group, a carbonyloxy group, a sulfide group, or a sulfone group. Substituents for the above groups include alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, phenyl groups, and aralkyl groups.

[0144] Preferred examples of Y include a single bond, a methylene group, -CH(CH3)2-, an ether bond, an optionally substituted cycloalkylene group, and an optionally substituted 9,9-fluorenylene group. n is an integer of 0 to 4, and is preferably 0 or 1. Specifically, B is a structure represented by the following general formula (B1) or (B2).

[0145] [ka]

[0146] In the general formula (B1) and the general formula (B2), Ar and Y have the same meanings as in the general formula (B). A is a substituted or unsubstituted arylene group linked via an aliphatic cyclic hydrocarbon group; Ar' is a substituted or unsubstituted aryl group; k is the average value of the repeating units and is in the range of 0.25 to 3.5.

[0147] The resin composition for forming a circuit board of this embodiment contains a specific active ester curing agent, and the resulting cured product can have excellent dielectric properties and an excellent low dielectric loss tangent.

[0148] The active ester curing agent (C) used in the resin composition for forming a circuit board of this embodiment has an active ester group represented by formula (B). In the curing reaction between the epoxy resin and the active ester curing agent, the active ester group of the active ester curing agent reacts with the epoxy group of the epoxy resin to generate a secondary hydroxyl group. This secondary hydroxyl group is blocked by the ester residue of the active ester curing agent. This reduces the dielectric tangent of the cured product. In one embodiment, the structure represented by the above formula (B) is preferably at least one selected from the following formulae (B-1) to (B-6).

[0149] [ka]

[0150] In formulas (B-1) to (B-6), R 1 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl group,

[0151] R 2 are each independently any one of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a phenyl group, and X is any one of a linear alkylene group having 2 to 6 carbon atoms, an ether bond, a carbonyl group, a carbonyloxy group, a sulfide group, and a sulfone group, n is an integer of 0 to 4, and p is an integer of 1 to 4.

[0152] The structures represented by the above formulas (B-1) to (B-6) are all highly oriented structures. Therefore, when an active ester curing agent containing such a structure is used, the resulting cured resin composition for forming a circuit board has a low dielectric tangent and excellent adhesion to metals, and is therefore suitable for use as a semiconductor encapsulation material.

[0153] Among them, from the viewpoint of low dielectric loss tangent, active ester curing agents having a structure represented by formula (B-2), formula (B-3) or formula (B-5) are preferred, and more preferred are active ester curing agents having a structure in which n is 0 in formula (B-2), a structure in which X is an ether bond in formula (B-3), or a structure in formula (B-5) in which two carbonyloxy groups are at the 4,4'-positions. 1 are preferably all hydrogen atoms.

[0154] In formula (1), "Ar'" is an aryl group, such as a phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 3,5-xylyl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, 2-benzylphenyl group, 4-benzylphenyl group, 4-(α-cumyl)phenyl group, 1-naphthyl group, 2-naphthyl group, etc. Among these, a 1-naphthyl group or a 2-naphthyl group is preferred, as this gives a cured product with a particularly low dielectric dissipation factor.

[0155] In this embodiment, "A" in the active ester curing agent represented by formula (1) is a substituted or unsubstituted arylene group linked via an aliphatic cyclic hydrocarbon group. Examples of such arylene groups include a structure obtained by a polyaddition reaction between an unsaturated aliphatic cyclic hydrocarbon compound containing two double bonds in one molecule and a phenolic compound.

[0156] Examples of the unsaturated aliphatic cyclic hydrocarbon compound containing two double bonds per molecule include dicyclopentadiene, cyclopentadiene polymers, tetrahydroindene, 4-vinylcyclohexene, 5-vinyl-2-norbornene, and limonene. These may be used alone or in combination of two or more. Among these, dicyclopentadiene is preferred because it can produce cured products with excellent heat resistance. Since dicyclopentadiene is contained in petroleum fractions, industrial dicyclopentadiene may contain cyclopentadiene polymers and other aliphatic or aromatic diene compounds as impurities. However, considering performance such as heat resistance, curability, and moldability, it is desirable to use a dicyclopentadiene product with a purity of 90% by mass or higher.

[0157] On the other hand, examples of the phenolic compound include phenol, cresol, xylenol, ethylphenol, isopropylphenol, butylphenol, octylphenol, nonylphenol, vinylphenol, isopropenylphenol, allylphenol, phenylphenol, benzylphenol, chlorophenol, bromophenol, 1-naphthol, 2-naphthol, 1,4-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, etc., and these may be used alone or in combination of two or more. Among these, phenol is preferred because it serves as an active ester curing agent with high curability and excellent dielectric properties in the cured product.

[0158] In a preferred embodiment, "A" in the active ester curing agent represented by formula (1) has a structure represented by formula (A): A resin composition containing an active ester curing agent in which "A" in formula (1) has the following structure produces a cured product with a low dielectric tangent and excellent adhesion.

[0159] [ka]

[0160] In formula (A), R 3 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl group, l is 0 or 1, and m is an integer of 1 or more.

[0161] Among the active ester curing agents represented by formula (1), more preferred are resins represented by the following formulas (1-1), (1-2) and (1-3), and particularly preferred is resin represented by the following formula (1-3).

[0162] [ka]

[0163] In formula (1-1), R 1 and R 3 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl group; Z is a phenyl group, a naphthyl group, or a phenyl group or naphthyl group having 1 to 3 alkyl groups having 1 to 4 carbon atoms on the aromatic nucleus; l is 0 or 1; and k is the average of the repeating units and is 0.25 to 3.5.

[0164] [ka]

[0165] In formula (1-2), R 1 and R 3 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl group; Z is a phenyl group, a naphthyl group, or a phenyl group or naphthyl group having 1 to 3 alkyl groups having 1 to 4 carbon atoms on the aromatic nucleus; l is 0 or 1; and k is the average of the repeating units and is 0.25 to 3.5.

[0166] [ka]

[0167] In formula (1-3), R 1 and R 3 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, or an aralkyl group; Z is a phenyl group, a naphthyl group, or a phenyl group or naphthyl group having 1 to 3 alkyl groups having 1 to 4 carbon atoms on the aromatic nucleus; l is 0 or 1; and k is the average of the repeating units and is 0.25 to 3.5.

[0168] The active ester curing agent (C) used in the present invention can be produced by a known method in which a phenolic compound (a) having a structure in which multiple aryl groups each having a phenolic hydroxyl group are linked via an aliphatic cyclic hydrocarbon group, an aromatic nucleus-containing dicarboxylic acid or its halide (b), and an aromatic monohydroxy compound (c) are reacted.

[0169] The reaction ratios of the phenolic compound (a), aromatic nucleus-containing dicarboxylic acid or its halide (b), and aromatic monohydroxy compound (c) can be appropriately adjusted depending on the desired molecular design. Among these, since an active ester curing agent with higher curing properties can be obtained, it is preferable to use the respective raw materials in a ratio such that the phenolic hydroxyl groups of the phenolic compound (a) are in the range of 0.25 to 0.90 moles and the hydroxyl groups of the aromatic monohydroxy compound (c) are in the range of 0.10 to 0.75 moles per mole of the total of carboxyl groups or acid halide groups of the aromatic nucleus-containing dicarboxylic acid or its halide (b), and it is more preferable to use the respective raw materials in a ratio such that the phenolic hydroxyl groups of the phenolic compound (a) are in the range of 0.50 to 0.75 moles and the hydroxyl groups of the aromatic monohydroxy compound (c) are in the range of 0.25 to 0.50 moles.

[0170] Furthermore, when the total number of functional groups in the resin is the sum of the arylcarbonyloxy groups and phenolic hydroxyl groups in the resin structure, the functional group equivalent of the active ester curing agent (C) is preferably in the range of 200 g / eq or more and 230 g / eq or less, and more preferably in the range of 210 g / eq or more and 220 g / eq or less, in order to obtain a cured product with excellent curability and low dielectric constant and dielectric dissipation factor.

[0171] In the resin composition for forming a circuit board of this embodiment, the blending amounts of the active ester curing agent (C) and the epoxy resin are preferably such that the epoxy groups in the epoxy resin are 0.8 to 1.2 equivalents per equivalent of the total active groups in the active ester curing agent (C), since this results in a cured product with excellent curing properties and a low dielectric loss tangent. Here, the active groups in the active ester curing agent (C) refer to arylcarbonyloxy groups and phenolic hydroxyl groups in the resin structure.

[0172] The active ester curing agent (C) is used in an amount of preferably 1 mass % or more and 50 mass % or less, more preferably 3 mass % or more and 40 mass % or less, and even more preferably 5 mass % or more and 35 mass % or less, based on the total solid content mass of the resin composition. By including the specific active ester curing agent in the above range, the resulting cured product can have better dielectric properties and an even lower dielectric loss tangent.

[0173] The resin blocking material of this embodiment uses a combination of the active ester curing agent (C) and the hollow silica particles (A) described above, and thereby has an excellent low dielectric tangent, and these effects are also excellent in the high frequency band.

[0174] [Silica particles (D)] The resin composition for forming a circuit board of this embodiment can further contain silica particles (D) (excluding the hollow silica particles (A)). By using these in combination, the linear expansion coefficient can be reduced while maintaining a low dielectric loss tangent.

[0175] The silica particles (D) may be spherical. The average particle size of the silica particles is not particularly limited, but may be, for example, 5.0 μm or less, 0.1 μm or more to 4.0 μm or less, or 0.2 μm or more to 2.0 μm or less. This can further improve the filling property of the inorganic filler (e).

[0176] The average particle diameter can be determined by measuring the particle size distribution of the particles on a volume basis using, for example, a laser diffraction particle size distribution analyzer (LA-500, manufactured by HORIBA Corporation), and determining the particle diameter at 50% of the cumulative size (D50) as the average particle diameter.

[0177] The resin composition for forming a circuit board of this embodiment preferably contains silica particles (D) in addition to the hollow silica particles (A). When these are used in combination, the content of the hollow silica particles (A) is preferably 1 to 50 mass %, more preferably 2 to 40 mass %, and even more preferably 3 to 30 mass %, based on the total solid mass of the resin composition. The content of the silica particles (D) is preferably 2 to 80 mass %, more preferably 3 to 70 mass %, and even more preferably 5 to 65 mass %, based on the total solid mass of the resin composition.

[0178] When the hollow silica particles (A) and the silica particles (D) are used in combination, the content of the hollow silica particles (A) is preferably 1.5 to 80% by volume, more preferably 3 to 60% by volume, and even more preferably 5 to 50% by volume, based on the total solid content volume of the resin composition. The content of the silica particles (D) is preferably 1.5 to 50% by volume, more preferably 2 to 45% by volume, and even more preferably 3 to 40% by volume, based on the total solid mass of the resin composition.

[0179] By setting the content of the hollow silica particles (A) and the silica particles (D) within the above range, it is possible to reduce the linear expansion coefficient while maintaining a low dielectric tangent, i.e., to obtain a cured product with an excellent balance between these properties.

[0180] [Other ingredients] The resin composition for forming a circuit board of this embodiment may contain additives other than those described above, such as resins other than those described above, crosslinking agents, curing accelerators, flame retardants, polymerization initiators, coupling agents, colorants including one or more selected from the group consisting of dyes such as green, red, blue, yellow, and black, pigments such as black pigments, and coloring materials, stress reducing agents, antifoaming agents, leveling agents, ultraviolet absorbers, foaming agents, antioxidants, ion scavengers, and rubber components, provided that the object of the present invention is not impaired. These may be used alone or in combination of two or more.

[0181] Examples of resins other than those mentioned above include thermosetting resins such as benzocyclobutene resin, thermoplastic resins, and phenoxy resins.

[0182] [Crosslinking agent] The crosslinking agent can be one that has the ability to initiate or accelerate a crosslinking reaction. From the viewpoint of the crosslinking reaction, the crosslinking agent preferably has an average of two or more carbon-carbon unsaturated double bonds or isocyanate groups (-N=C=O) per molecule. The crosslinking agent may be composed of one type of compound or two or more types of compounds.

[0183] Examples of crosslinking agents include trialkenyl isocyanurate compounds such as triallyl isocyanurate (TAIC) and trimethallyl isocyanurate, trialkenyl cyanurate compounds such as triallyl cyanurate (TAC), polyfunctional methacrylate compounds having two or more methacrylic groups in the molecule, polyfunctional acrylate compounds having two or more acrylic groups in the molecule, polyfunctional vinyl compounds having two or more vinyl groups in the molecule such as polybutadiene, vinylbenzyl compounds such as divinylbenzene having a vinylbenzyl group in the molecule, polyfunctional maleimide compounds having two or more maleimide groups in the molecule such as 4,4'-bismaleimide diphenylmethane (excluding the maleimide resins), and isocyanate compounds having one or more isocyanate groups (-N=C=O). These may be used alone or in combination of two or more.

[0184] Among these, the crosslinking agent preferably contains at least one compound selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, polybutadiene, and divinylbenzene, which further increases the crosslink density during the curing reaction (crosslinking reaction) while maintaining good impregnation properties, thereby improving the heat resistance of the cured product of the resin composition. The number average molecular weight of the crosslinking agent is preferably 600 to 4,000, and more preferably 800 to 2,000.

[0185] By setting the number-average molecular weight of the crosslinking agent to the above lower limit or more, the reactivity is increased and a good cured product is obtained. By setting the number-average molecular weight of the crosslinking agent to the above upper limit or less, an increase in the viscosity of the resin composition can be suppressed, resulting in good impregnation properties. In addition, good resin flowability during heat molding can be obtained. The number average molecular weight may be measured by a general molecular weight measurement method, and specifically, a value measured using GPC may be mentioned.

[0186] The content of the crosslinking agent is preferably 1 to 30 mass %, more preferably 2 to 20 mass %, and even more preferably 4 to 18 mass %, relative to the total solid mass of the resin composition of this embodiment.

[0187] (curing accelerator) As the curing accelerator (curing catalyst) of this embodiment, known ones can be used. Examples of the organic compounds include organic metal salts such as zinc naphthenate, cobalt naphthenate, tin octoate, cobalt octoate, zinc octoate, bisacetylacetonate cobalt(II), and trisacetylacetonate cobalt(III); tertiary amines such as triethylamine, tributylamine, and diazabicyclo[2,2,2]octane; imidazoles such as 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 2-phenyl-4-methylimidazole, 2-ethyl-4-ethylimidazole, 2-phenyl-4-ethylimidazole, 2-phenyl-4-methyl-5-hydroxyimidazole, and 2-phenyl-4,5-dihydroxyimidazole; phenolic compounds such as phenol, bisphenol A, and nonylphenol; organic acids such as acetic acid, benzoic acid, salicylic acid, and paratoluenesulfonic acid; and onium salt compounds and derivatives thereof. These may be used alone or in combination of two or more. Among these, imidazole and onium salt compounds are preferred from the viewpoint of stably improving the resin curability. Such onium salt compounds are not particularly limited, but examples thereof include onium salt compounds represented by the following formula (IX):

[0188] [ka]

[0189] In formula (IX), P represents a phosphorus atom, R 1 , R 2 , R 3 and R 4 A each represents an organic group having a substituted or unsubstituted aromatic ring or heterocyclic ring, or a substituted or unsubstituted aliphatic group, and may be the same or different. - represents an anion of a proton donor with a valence of n (n≧1) that has at least one proton in the molecule that can be released outside the molecule, or a complex anion thereof.

[0190] The content of the curing accelerator is not particularly limited, but is preferably 0.005 to 5 mass % and more preferably 0.01 to 2 mass % of the total resin composition (solid content). By setting the content of the curing accelerator to the above lower limit or more, a good curing acceleration effect can be obtained, while by setting the content of the curing accelerator to the above lower limit or more, the prepreg can be kept in a good state of storage.

[0191] [Flame retardant] In this embodiment, examples of the flame retardant include halogen-based flame retardants such as bromine-based flame retardants and phosphorus-based flame retardants. Specific examples of halogen-based flame retardants include bromine-based flame retardants such as pentabromodiphenyl ether, octabromodiphenyl ether, decabromodiphenyl ether, tetrabromobisphenol A, and hexabromocyclododecane, and chlorine-based flame retardants such as chlorinated paraffin. Specific examples of phosphorus-based flame retardants include phosphate esters such as condensed phosphate esters and cyclic phosphate esters, phosphazene compounds such as cyclic phosphazene compounds, phosphinate-based flame retardants such as metal phosphinates such as aluminum dialkylphosphinates, and melamine-based flame retardants such as melamine phosphate and melamine polyphosphate. The flame retardants listed above may be used alone or in combination of two or more. Among these, phosphorus-based flame retardants are preferred.

[0192] The content of the flame retardant is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 1 to 5 parts by mass, per 100 parts by mass of the total solid content of the resin composition.

[0193] [Polymerization initiator] The resin composition for forming a circuit board according to this embodiment may contain a polymerization initiator. This allows component (f) to cure stably regardless of the process conditions. The polymerization initiator is not particularly limited as long as it can accelerate the curing reaction between the modified polyphenylene ether and the thermosetting curing agent. Examples of the polymerization initiator include oxidizing agents such as 1,3-di(t-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, benzoyl peroxide, 3,3',5,5'-tetramethyl-1,4-diphenoquinone, chloranil, 2,4,6-tri-t-butylphenoxyl, t-butylperoxyisopropyl monocarbonate, and azobisisobutyronitrile. These may be used alone or in combination of two or more. Furthermore, to further accelerate the curing reaction, a metal carboxylate or the like may be used in combination.

[0194] Among these, α,α'-bis(t-butylperoxy-m-isopropyl)benzene is preferably used. α,α'-bis(t-butylperoxy-m-isopropyl)benzene has a relatively high reaction initiation temperature, which can suppress the promotion of the curing reaction when curing is not required, such as during prepreg drying, and can suppress a decrease in the storage stability of the resin composition of this embodiment. Furthermore, α,α'-bis(t-butylperoxy-m-isopropyl)benzene has low volatility, so it does not volatilize during prepreg drying or storage, and good stability is obtained.

[0195] [Coupling agent] The resin composition for forming a circuit board of this embodiment may contain a coupling agent. The coupling agent may be added directly during preparation of the resin composition, or may be added to the hollow silica particles (A) in advance. The use of a coupling agent can improve the wettability at the interface between the hollow silica particles (A) and each resin. Therefore, the use of a coupling agent is preferable, and the heat resistance of the cured resin film can be improved. Furthermore, the use of a coupling agent can improve adhesion to copper foil. Furthermore, since moisture absorption resistance can be improved, adhesion to copper foil can be maintained even in a humid environment.

[0196] Examples of the coupling agent include silane coupling agents such as vinyl silane coupling agents, epoxy silane coupling agents, cationic silane coupling agents, and amino silane coupling agents, titanate coupling agents, and silicone oil coupling agents. One type of coupling agent may be used alone, or two or more types may be used in combination. In this embodiment, the coupling agent may contain a silane coupling agent. This can increase the wettability at the interface between the hollow silica particles (A) and each resin, and can further improve the heat resistance of the cured resin film.

[0197] As the silane coupling agent, various types can be used, and examples thereof include epoxy silane, amino silane, alkyl silane, ureido silane, mercapto silane, and vinyl silane.

[0198] Specific compounds include, for example, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-phenylγ-aminopropyltriethoxysilane, N-phenylγ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, N-6-(aminohexyl)3-aminopropyltrimethoxysilane, N-(3-(trimethoxysilylpropyl)-1,3-benzenedimethanane, γ-glycidoxypropyl Examples include vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, γ-ureidopropyltriethoxysilane, vinyltriethoxysilane, etc., and one or more of these can be used in combination. Among these, vinylsilane, epoxysilane, mercaptosilane, and aminosilane are preferred, and as the aminosilane, primary aminosilane or anilinosilane is more preferred.

[0199] The content of the coupling agent can be appropriately adjusted based on the specific surface area of ​​the hollow silica particles (A). The lower limit of the content of such a coupling agent may be, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, relative to 100 parts by mass of the total solid content of the resin composition. When the content of the coupling agent is equal to or more than the lower limit, the inorganic filler (e) can be sufficiently coated, and the heat resistance of the cured resin film can be improved. On the other hand, the upper limit of the content of the coupling agent may be, for example, 3 parts by mass or less, preferably 1.5 parts by mass or less, relative to 100 parts by mass of the total solid content of the resin composition. When the content of the coupling agent is equal to or less than the upper limit, the effect on the reaction can be suppressed, and a decrease in the bending strength of the cured resin film can be suppressed.

[0200] <Resin composition for circuit board formation> The resin composition for forming a circuit board of this embodiment contains hollow silica particles (A) and a resin (B). This resin composition provides a cured product that has a low dielectric constant, a low dielectric loss tangent, and excellent peel strength against copper foil.

[0201] The dielectric loss tangent Df at 10 GHz of the cured product of the resin composition for forming a circuit board of this embodiment is 0.0032 or less, preferably 0.0030 or less, and more preferably 0.0029 or less. The lower limit is not particularly limited, but is 0.0010 or more.

[0202] The dielectric constant Dk at 10 GHz of the cured product of the resin composition for forming a circuit board of this embodiment is 1.8 or more and 2.8 or less, preferably 2.0 or more and 2.7 or less, and more preferably 2.1 or more and 2.6 or less.

[0203] In this embodiment, the dielectric loss tangent Df and the dielectric constant Dk are measured, for example, as follows. A resin varnish, which will be described later and is made of the resin composition for forming a circuit board of this embodiment, is applied to one side of a 38 μm thick PET film using a comma coater so that the total thickness of the resin layer after drying is 30 μm, and this is dried for 3 minutes in a drying device at 160°C to obtain a resin sheet (resin film with carrier) in which a resin film is laminated on the PET film. Next, four 30 μm thick resin films with a carrier were stacked on top of each other, and hot pressed with copper foil at 200°C and 0.5 kgf / mm 2 The resin film is cured by heating and pressing for 2 hours under the pressing conditions of 1. The copper foil is then removed by etching from the resulting laminate to prepare a cured film, and the dielectric loss tangent of the cured film at 10 GHz is measured using a cavity resonator method.

[0204] The dielectric constant and dielectric loss tangent can be controlled by known methods, such as by appropriately selecting the type and amount of each component contained in the resin composition for forming a circuit board, the method for preparing the resin composition, etc.

[0205] The peel strength of the cured film made of the resin composition for forming a circuit board of this embodiment against copper foil is preferably 0.3 kN / m or more, more preferably 0.4 kN / m or more, and although there is no particular upper limit, it is 3.0 kN / m or less. This provides high adhesion to the copper foil.

[0206] In this embodiment, the peel strength is measured in accordance with ISC-6481, by using a laminate obtained by measuring the dielectric loss tangent Df and the dielectric constant Dk, and peeling the cured film from the copper foil. The peel strength of the highly dielectric resin composition of the present embodiment can be controlled by the amount of hollow silica particles (A) added, the number of polar functional groups in the resin composition, and the like.

[0207] The resin composition for forming a circuit board of this embodiment can adjust the linear expansion coefficient by using the hollow silica particles (A) and the silica particles (D) (excluding the hollow silica particles (A)) in combination. The linear expansion coefficient of the cured product of the resin composition for forming a circuit board of this embodiment can be adjusted to 80 ppm / °C or more and 130 ppm / °C or less, preferably 85 ppm / °C or more and 125 ppm / °C or less, and more preferably 90 ppm / °C or more and 120 ppm / °C or less.

[0208] The coefficient of linear expansion (CTE) is measured using a TMA (thermal mechanical analysis) device by preparing a 4 mm x 20 mm test piece and measuring it at a temperature range of 30 to 300°C, at 10°C / min, under a load of 5 g, at 50 to 100°C in the second cycle. The test piece can be obtained by removing the copper foil from the laminate obtained in the measurement of the dielectric loss tangent Df and the dielectric constant Dk.

[0209] By setting the linear expansion coefficient within the above range, it is possible to reduce the difference in linear expansion coefficient from the semiconductor chip while maintaining a low dielectric loss tangent and a low dielectric constant, and it becomes easier to suppress warpage of the entire semiconductor package.

[0210] The linear expansion coefficient can be controlled by known methods, such as by appropriately selecting the mixing ratio of the hollow silica particles (A) and the silica particles (D) (excluding the hollow silica particles (A)), the type and amount of each component contained in the resin composition for forming a circuit board, and the method for preparing the resin composition.

[0211] (Varnish-like resin composition) In this embodiment, the varnish-like resin composition may contain a solvent. The resin composition for forming a circuit board according to the present embodiment contains the above-described components, and therefore can be used to form a varnish with a low viscosity. As a result, the impregnation into the substrate can be improved, workability can be improved, and adhesion can be improved.

[0212] Examples of the solvent include organic solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, mesitylene, ethyl acetate, cyclohexane, heptane, cyclohexane, cyclohexanone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene glycol, ethylene glycol ether, cellosolves, carbitols, anisole, and N-methylpyrrolidone. These may be used alone or in combination of two or more.

[0213] Among these, from the viewpoint of minimizing the change in peel strength, toluene, heptane, cyclohexane, anisole, and mesitylene are preferred, toluene is more preferred, and a solvent containing at least 5% or more toluene is even more preferred. These solvents have excellent solubility and compatibility with the above resins, so that the change in peel strength can be reduced. In addition, the solvent can be dried efficiently.

[0214] From the viewpoint of promoting compatibility and adhesion with the inorganic filler (e) such as silica and reducing changes in peel strength, it is preferable to use methyl isobutyl ketone, cyclohexanone, or ethylene glycol ether.

[0215] When the resin composition is in the form of a varnish, the solid content of the resin composition may be, for example, 30% by mass to 80% by mass, more preferably 40% by mass to 70% by mass, which results in a resin composition with excellent workability and film-forming properties.

[0216] The varnish-like resin composition can be prepared by dissolving, mixing, and stirring the above-mentioned components in a solvent using various mixers, such as those used in ultrasonic dispersion, high-pressure collision dispersion, high-speed rotation dispersion, bead mill dispersion, high-speed shear dispersion, and rotation-revolution dispersion.

[0217] The resin composition for forming a circuit board of the present embodiment can be used to form circuit boards such as resin sheets, resin films with carriers, prepregs, laminates, and printed wiring boards, as well as wiring boards having a dielectric substrate used in an antenna having a power feed circuit.

[0218] <Resin sheet> Next, the resin sheet (resin film) of this embodiment will be described. The resin sheet of this embodiment can be obtained by forming the resin composition in a varnish form into a film. For example, the resin sheet of this embodiment can be obtained by applying the resin composition in a varnish form to a coating film and then removing the solvent from the coating film. In such a resin sheet, the solvent content can be 5 mass % or less based on the entire resin film. In this embodiment, the solvent removal step can be carried out under conditions of, for example, 100°C to 150°C and 1 minute to 5 minutes. This makes it possible to sufficiently remove the solvent while suppressing the progress of curing of the resin film containing a thermosetting resin. The resin sheet of the present embodiment may be composed of a resin film alone, or may be composed so as to contain a fiber base material inside.

[0219] <Prepreg> The prepreg of this embodiment is obtained by impregnating a fiber substrate with the resin composition. For example, the prepreg can be used as a sheet-like material obtained by impregnating a fiber substrate with the resin composition and then semi-curing the material. A sheet-like material having such a structure has excellent properties such as dielectric properties and mechanical and electrical connection reliability under high temperature and humidity conditions, and is suitable for producing an insulating layer for a printed wiring board, for example.

[0220] In this embodiment, the method for impregnating the resin composition into the fiber substrate is not particularly limited, but examples include a method in which the resin composition is dissolved in a solvent to prepare a resin varnish and the fiber substrate is immersed in the resin varnish, a method in which the resin varnish is applied to the fiber substrate using various coaters, a method in which the resin varnish is sprayed onto the fiber substrate using a sprayer, and a method in which both sides of the fiber substrate are laminated with the resin film made of the resin composition.

[0221] Examples of the fiber substrate include glass fiber substrates such as woven glass cloth and nonwoven glass cloth, inorganic fiber substrates such as woven or nonwoven cloth containing an inorganic compound other than glass as a component, and organic fiber substrates made of organic fibers such as aromatic polyamideimide resin, polyamide resin, aromatic polyester resin, polyester resin, polyimide resin, fluororesin, etc. Among these substrates, the use of a glass fiber substrate typified by woven glass cloth in terms of strength can improve the mechanical strength and heat resistance of the printed wiring board.

[0222] The thickness of the fiber base material is not particularly limited, but is preferably 5 μm to 150 μm, more preferably 10 μm to 100 μm, and even more preferably 12 μm to 90 μm. Use of a fiber base material having such a thickness can further improve the handleability during prepreg production.

[0223] When the thickness of the fiber substrate is equal to or less than the upper limit, the impregnation of the resin composition into the fiber substrate is improved, and the occurrence of strand voids and a decrease in insulation reliability can be suppressed. Furthermore, the formation of through-holes using carbon dioxide, UV, excimer, or other lasers can be facilitated. Furthermore, when the thickness of the fiber substrate is equal to or greater than the lower limit, the strength of the fiber substrate and prepreg can be improved. As a result, handling can be improved, prepreg production can be facilitated, and warping of the resin substrate can be suppressed.

[0224] As the glass fiber substrate, for example, a glass fiber substrate formed of one or more types of glass selected from E glass, S glass, D glass, T glass, NE glass, UT glass, L glass, HP glass, and quartz glass is preferably used.

[0225] In this embodiment, the prepreg can be used to form, for example, an insulating layer in a build-up layer or an insulating layer in a core layer of a printed wiring board. When the prepreg is used to form an insulating layer in a core layer of a printed wiring board, for example, two or more prepregs can be stacked and the resulting laminate can be heat-cured to form an insulating layer for the core layer.

[0226] <Metal-clad laminate> The laminate of this embodiment is a metal-clad laminate in which a metal layer is disposed on at least one surface of the cured product of the prepreg. A method for manufacturing a metal-clad laminate using a prepreg is, for example, as follows.

[0227] Metal foil is placed on both or one of the outer surfaces of a prepreg or a laminate of two or more prepregs, and these are bonded under high vacuum conditions using a laminator or Becquerel apparatus, or metal foil is placed on both or one of the outer surfaces of the prepreg. When two or more prepregs are laminated, metal foil is placed on both or one of the outermost surfaces of the laminated prepregs. The laminate of prepregs and metal foil is then heated and pressurized to obtain a metal-clad laminate. It is preferable to continue pressing during the heating and pressurizing process until cooling is complete.

[0228] Examples of metals constituting the metal foil include copper, copper-based alloys, aluminum, aluminum-based alloys, silver, silver-based alloys, gold, gold-based alloys, zinc, zinc-based alloys, nickel, nickel-based alloys, tin, tin-based alloys, iron, iron-based alloys, Fe-Ni-based alloys such as Kovar (trade name), 42 alloy, Invar, and Super Invar, W, and Mo. Among these, copper or copper alloys are preferred as the metal constituting the metal foil 105 because they have excellent conductivity, are easy to form circuits by etching, and are inexpensive. That is, copper foil is preferred as the metal foil. As the metal foil, a metal foil with a carrier or the like can also be used. The thickness of the metal foil is preferably 0.5 μm or more and 20 μm or less, and more preferably 1.5 μm or more and 18 μm or less.

[0229] <Resin film with carrier> FIG. 1(a) is a cross-sectional view showing an example of the configuration of a resin film 10 with a carrier in this embodiment.

[0230] As shown in Fig. 1(a), the resin film 10 with a carrier of this embodiment can include a carrier substrate 40, a primer layer 30 for a plating process provided on the carrier substrate 40, and an insulating film 20 that serves as a base for the plating layer. In the resin film 10 with a carrier, it is preferable that at least one of the primer layer 30 and the insulating film 20 is made of a resin film made of the above-mentioned resin composition. This can improve the handleability of the resin film.

[0231] 1(b), the resin film 12 with a carrier of this embodiment can include a carrier substrate 40 and a resin film made of the resin composition formed on the carrier substrate 40. The resin film can be used as an insulating film 20 that serves as a base for a plating layer.

[0232] The resin films 10 and 12 with a carrier may be in a roll shape that can be wound up, or in a sheet shape such as a rectangular shape. The surfaces of the resin films 10 and 12 with a carrier may be exposed, or may be covered with a protective film (cover film). As the protective film, a film having a known protective function may be used, and for example, a PET film may be used.

[0233] In this embodiment, the carrier substrate 40 can be, for example, a polymer film or a metal foil. Examples of the polymer film include, but are not limited to, polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate; release paper such as silicone sheets; and heat-resistant thermoplastic resin sheets such as fluorine-based resins and polyimide resins. Examples of the metal foil include, but are not limited to, copper and / or copper-based alloys, aluminum and / or aluminum-based alloys, iron and / or iron-based alloys, silver and / or silver-based alloys, gold and gold-based alloys, zinc and zinc-based alloys, nickel and nickel-based alloys, and tin and tin-based alloys. Among these, a polyethylene terephthalate sheet is most preferred due to its low cost and easy peel strength adjustment. This allows for easy peeling from the carrier-attached resin film 10 with an appropriate strength.

[0234] The lower limit of the thickness of the resin film is not particularly limited, but may be, for example, 1 μm or more, 3 μm or more, or 5 μm or more. This allows the mechanical strength of the resin film 10 to be increased. On the other hand, the upper limit of the thickness of the resin film 10 is not particularly limited, but may be, for example, 500 μm or less, 300 μm or less, or 100 μm or less. This allows the semiconductor device to be made thinner. The thickness of the resin film may be the thickness of the insulating film 20, or the combined thickness of the insulating film 20 and the primer layer 30.

[0235] The lower limit of the thickness of the primer layer 30 is, for example, 1 μm or more, and preferably 2 μm or more. This can improve insulation reliability. On the other hand, the upper limit of the thickness of the primer layer 30 is, for example, 10 μm or less, and preferably 8 μm or less. This can achieve a thinner printed wiring board. Furthermore, by setting the thickness of the primer layer 30 within the above range, a printed wiring board that can accommodate thinner thicknesses can be obtained without losing the properties of the insulating layer in the build-up layer.

[0236] The lower limit of the thickness of the insulating film 20 is, for example, 5 μm or more, and preferably 10 μm or more. This can improve insulation reliability. On the other hand, the upper limit of the thickness of the insulating film 20 is, for example, 50 μm or less, and preferably 40 μm or less. This can achieve a thinner printed wiring board. Furthermore, by setting the thickness of the insulating film 20 within the above range, it is possible to fill the irregularities of the inner layer circuit when manufacturing the printed wiring board, and it is also possible to ensure a suitable thickness of the insulating resin layer of the build-up layer.

[0237] The thickness of the carrier substrate 40 is not particularly limited, but may be, for example, 10 μm or more and 100 μm or less, or 10 μm or more and 70 μm or less, which is preferable because it improves the handleability when producing the carrier-attached resin film 10.

[0238] The resin film of the carrier-attached resin film 10 of this embodiment may be a single layer or a multilayer, and may be composed of one or more types of films. When the resin sheet is multilayered, it may be composed of the same type or different types. Furthermore, the carrier-attached resin film 10 may have a protective film on the outermost layer side of the resin film 10.

[0239] The resin sheet of this embodiment is a resin sheet made of the resin composition for forming a circuit board. The cured film of the resin film is composed of a cured product of the resin composition. The cured film of the cured product of the resin composition can be used as an insulating layer that constitutes a build-up layer of a printed wiring board.

[0240] <Printed wiring board> The printed wiring board of this embodiment is provided with an insulating layer made of the cured product of the above-mentioned resin sheet (cured product of the resin composition).

[0241] In this embodiment, the cured resin sheet can be used, for example, as a buildup layer of a normal printed wiring board, a buildup layer in a printed wiring board having no core layer, a buildup layer in a coreless substrate used in PLP, a buildup layer in an MIS substrate, etc. The insulating layer constituting such a buildup layer can also be suitably used as a buildup layer constituting a large-area printed wiring board used to collectively produce multiple semiconductor packages.

[0242] In the present embodiment, a resin sheet made of a resin composition for forming an insulating film may be impregnated with glass fibers. In a semiconductor package using such a resin film as a build-up layer, the linear expansion coefficient of the cured resin film can be reduced, and package warpage can be sufficiently suppressed.

[0243] (Semiconductor package) 2A to 2C are cross-sectional views showing an example of a manufacturing process for the semiconductor package 200 of this embodiment.

[0244] The semiconductor device (semiconductor package 200) of this embodiment can include a printed wiring board and a semiconductor element 240 mounted on a circuit layer of the printed wiring board or embedded in the printed wiring board. An outline of the manufacturing process for the semiconductor package 200 of this embodiment will be described below.

[0245] First, as shown in FIG. 2(a), a core substrate 100 is prepared, which includes an insulating layer 102, via holes 104, and a metal layer 108. The via holes 104 are formed in the insulating layer 102. A metal layer (via) is embedded in the via holes 104. The metal layer may be covered with an electroless metal plating film 106. The metal layer 108 (a circuit layer having a predetermined circuit pattern) formed on the surface of the insulating layer 102 is electrically connected to the vias formed in the via holes 104. In FIG. 2(a), the metal layer 108 is formed on one surface of the core substrate 100, but it may be formed on both surfaces.

[0246] Next, a resin film made of the resin composition for forming a circuit board is formed on one surface of the core substrate 100 so as to embed the metal layer 108. The resin film may be a multi-layer film including an insulating film 20 and a primer layer 30. Alternatively, the resin film may be a single layer of the insulating film 20 alone.

[0247] Subsequently, openings (not shown) are formed in the resin film. The openings can be formed so as to expose the metal layer 108. The method for forming the openings is not particularly limited, and may be, for example, a laser processing method, an exposure and development method, or a blasting method.

[0248] In this embodiment, after forming such openings, the resin film (insulating film 20, primer layer 30) may be thermally cured. This allows the resin film to be composed of a cured product of the resin composition for forming a circuit board of this embodiment.

[0249] If necessary, a desmearing process can be performed to remove smears generated inside the openings and roughen the surface of the resin film.

[0250] The desmearing method is not particularly limited, but can be performed, for example, as follows. First, the core substrate 100 laminated with a resin film is immersed in a swelling liquid containing an organic solvent, and then immersed in an alkaline permanganate aqueous solution to neutralize and roughen the substrate. Examples of organic solvents that can be used include diethylene glycol monobutyl ether and ethylene glycol. Examples of such swelling liquids include "Swelling Dip Securigant P" manufactured by Atotech Japan. Examples of permanganates that can be used include potassium permanganate and sodium permanganate. The temperature of the swelling liquid or the permanganate aqueous solution may be, for example, 50°C or higher and 100°C or lower. The immersion time in the swelling liquid or the permanganate aqueous solution may be, for example, 1 minute or longer and 30 minutes or shorter. In the desmearing step, only the wet desmearing described above can be performed, but plasma irradiation may also be performed in addition to the desmearing.

[0251] Next, an electroless metal plating film 202 is formed on the primer layer 30. An example of an electroless plating method will be described. For example, catalytic nuclei are applied to the surface of the primer layer 30, which is the base layer. The catalytic nuclei are not particularly limited, but may be, for example, precious metal ions or palladium colloid. Subsequently, the electroless metal plating film 202 is formed by electroless plating using the catalytic nuclei as the nuclei. For example, electroless plating containing copper sulfate, formalin, a complexing agent, sodium hydroxide, etc. may be used. After electroless plating, a heat treatment at 100°C or higher and 250°C or lower may be performed to stabilize the plating film.

[0252] Next, as shown in FIG. 2(b), a resist 204 having a predetermined opening pattern (openings 206) is formed on the electroless metal plating film 202. This opening pattern corresponds to, for example, a circuit pattern. The resist 204 is not particularly limited and any known material can be used, including liquid and dry films. In the case of forming fine wiring, a photosensitive dry film or the like can be used as the resist 204. An example using a photosensitive dry film will be described. For example, a photosensitive dry film is laminated on the electroless metal plating film 202, and the non-circuit formation area is exposed to light to harden it, and the unexposed area is dissolved and removed with a developer. The hardened photosensitive dry film is left behind to form the resist 204.

[0253] Next, as shown in FIG. 2( c), an electrolytic metal plating layer 208 is formed by electroplating at least within the opening pattern of the resist 204 and on the electroless metal plating film 202. The electroplating method is not particularly limited, but a known method used for ordinary printed wiring boards can be used, such as a method in which the substrate is immersed in a plating solution such as copper sulfate and an electric current is passed through the plating solution. The electrolytic metal plating layer 208 may have a single layer or a multilayer structure. The material for the electrolytic metal plating layer 208 is not particularly limited, but may be one or more of copper, copper alloy, 42 alloy, nickel, iron, chromium, tungsten, gold, and solder. Subsequently, as shown in FIG. 2(d), the resist 204 is removed using an alkaline remover, sulfuric acid, or a commercially available resist remover.

[0254] Next, as shown in FIG. 2( e), the electroless metal plating film 202 is removed from areas (openings 210) other than the area where the electrolytic metal plating layer 208 is formed. That is, the electroless metal plating film 202 underneath is selectively removed using the electrolytic metal plating layer 208 as a mask. For example, the electroless metal plating film 202 can be removed by soft etching (flash etching). Here, the soft etching process can be performed using an etching solution containing sulfuric acid and hydrogen peroxide. This allows the formation of a metal layer 220 having a predetermined pattern. In this way, the metal layer 220 composed of the electroless metal plating film 202 and the electrolytic metal plating layer 208 can be formed on the insulating layer made of the cured resin film of this embodiment by the semi-additive process (SAP).

[0255] Furthermore, a multilayer structure can be achieved by stacking build-up layers as needed on a printed wiring board composed of the core substrate 100 and the above build-up layers, and repeating the process of forming interlayer connections and circuits using a semi-additive process. In this way, the printed wiring board of this embodiment is obtained.

[0256] 2(f), build-up layers are laminated on the resulting printed wiring board as needed, and the steps of forming interlayer connections and circuits by a semi-additive process are repeated. Then, solder resist layers 230 are laminated on both sides or one side of the printed wiring board as needed.

[0257] The method for forming the solder resist layer 230 is not particularly limited, but may be, for example, a method in which a dry film type solder resist is laminated, exposed to light, and developed, or a method in which a liquid resist is printed and then exposed to light and developed.

[0258] Subsequently, a reflow process is performed to fix the semiconductor element 240 onto the connection terminals, which are part of the wiring pattern, via the solder bumps 250. Thereafter, the semiconductor element 240, the solder bumps 250, etc. are covered with an encapsulant layer 260 to be encapsulated. As a result of the above, the semiconductor package 200 shown in FIG. 2(f) is obtained.

[0259] <Wiring board> In this embodiment, the wiring board is a substrate (laminate) with metal foil on one or both sides of which a conductor layer is formed by etching the metal foil into a desired pattern on a dielectric substrate, allowing it to be used as a wiring board on which miniaturized, high-density components are mounted.

[0260] Furthermore, the wiring board of this embodiment can include a microstrip line (feed circuit) and a conductor plate (patch) on the dielectric substrate, the microstrip line including a microstrip line formed by etching the metal foil of a base material (laminate) with metal foil. Furthermore, various pads, vias, and patterns are added to the antenna and device circuit using the wiring board of this embodiment.

[0261] The above etching can be performed by chemical etching (wet etching), and the etching solution can be a copper chloride solution, nitric acid, or the like, or can be performed by a method using other acidic solutions, alkaline solutions, or the like.

[0262] The bonding with the metal foil can be carried out by a known method. For example, the adhesive film and the metal foil can be bonded by continuous processing using a hot roll laminating device having one or more pairs of metal rolls or a double belt press (DBP). Because the device configuration is simple and it is advantageous in terms of maintenance costs, the bonding of the adhesive film and the metal foil is preferably carried out by thermal lamination using a hot roll laminating device having one or more pairs of metal rolls.

[0263] The wiring board of this embodiment may be used in a high frequency band of microwaves, for example, 10 GHz to 100 GHz. In particular, by using a frequency of 60 GHz or higher, moisture absorption can be effectively suppressed, resulting in high reliability. Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted as long as they do not impair the effects of the present invention. [Example]

[0264] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. (Examples 1 to 7, Comparative Examples 1 to 3) Preparation of Resin Composition Each component was dissolved or dispersed at the solid content shown in Table 1, adjusted with toluene to a non-volatile content of 70% by mass, and stirred using a high-speed stirrer to prepare a varnish-like resin composition (resin varnish). The numerical values ​​showing the blending ratio of each component in Table 1 indicate the blending ratio (mass %) of each component relative to the total solid content of the resin composition.

[0265] Details of the raw materials for each component in Table 1 are as follows: Silica particles: Admatechs SC4050, average particle size 1.0 μm, anilide treated

[0266] Hollow silica particles 1: Hollow silica particles prepared by the following method (Method for preparing hollow silica particles 1) 7 g of polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer (ADEKA Corporation, "Pluronic F68") was added to 1250 g of purified water and stirred. 42 g of n-decane was added and stirred using a homogenizer until uniform, creating an emulsion. This emulsion was then high-pressure emulsified five times at 70 MPa using a high-pressure emulsifier (Ashizawa Finetech Co., Ltd., OMEGALAB) to reduce the emulsion diameter to 0.7 μm. The resulting fine emulsion was then allowed to stand at 40°C for 12 hours. Next, 23 g of diluted sodium silicate aqueous solution (SiO2 concentration 10.4 wt%, Na2O concentration 3.6 wt%) and 2 M hydrochloric acid were added to 1300 g of the emulsion to adjust the pH to 2, and the mixture was stirred thoroughly while maintaining the temperature at 30°C. Next, 1 M sodium hydroxide aqueous solution was slowly added dropwise with stirring to adjust the pH to 6, resulting in an oil core-silica shell particle dispersion. Next, the oil core-silica shell particle dispersion was allowed to stand at room temperature for 12 hours to mature. The entire oil-core-silica shell particle dispersion was heated to 70°C and stirred while slowly adding 1M NaOH to adjust the pH to 9. Next, 330 g of diluted sodium silicate aqueous solution (SiO2 concentration 10.4 wt%, Na2O concentration 3.6 wt%) was added with 0.5M hydrochloric acid to adjust the pH to 9. This suspension was held at 80°C for 1 day and then cooled to room temperature to obtain a hollow silica precursor dispersion. The entire hollow silica precursor dispersion was neutralized to pH 2 with 2M hydrochloric acid, filtered using a quantitative filter, and 350 ml of 80°C ion-exchanged water was added and pressure-filtered to wash the hollow silica cake. The hollow silica cake was then dried under a nitrogen atmosphere at 100°C for 1 hour and then at 400°C for 2 hours (heating rate 10°C / min) to remove organic matter, yielding a hollow silica precursor. Finally, the hollow silica precursor was calcined at 1000°C for 1 hour (heating rate 10°C / min) to densify the shell and obtain hollow silica particles. 10 g of the hollow silica particles, 150 ml of isopropanol, and 0.8 g of hexamethylsilazane were added and refluxed for 1 hour at 100° C. Thereafter, the mixture was filtered under reduced pressure using a hydrophobic PTFE membrane filter, washed with 20 ml of isopropanol, and then vacuum-dried for 2 hours in a vacuum dryer adjusted to 150° C. to obtain surface-treated hollow silica particles 1.

[0267] The physical properties of the hollow silica particles 1 were measured by the following methods. The results are shown in Table 1. (1) Average particle size The average particle diameter D of hollow silica particles 1 measured using a laser diffraction / scattering particle size distribution analyzer 50 was measured. (2) Weight reduction rate The weight loss rate of hollow silica particles 1 was measured under the following measurement conditions. Measurement conditions Measurement equipment: TG-DTA (Thermogravimetry-Differential Thermal Analysis) Atmosphere: atmospheric Measurement temperature: The temperature was raised from 30°C to 800°C at a rate of 10°C / min, and held at 800°C for 30 minutes. (3) Strength The pressure at which the pore volume reached its maximum value was measured by mercury intrusion porosimetry in accordance with JIS-R1655 (2003). Specifically, measurements were carried out using a mercury porosimeter (manufactured by Micrometrics, product name: AutoPore IV 9600). The pressure at which the pore volume reached its maximum was measured under the following measurement conditions: pressure 50 mmHg, evacuation time 5 minutes, injection pressure 0.5 to 43,600 psi, and equilibration time 10 seconds. (4) Hollowness ratio The hollow ratio of hollow silica particles 1 was measured by the pycnometer method using argon gas in accordance with JIS-R-1620 (1995) using an Auto Pycnometer 1320 (Micromeritics). The hollow ratio (%) was then calculated using the density ρ0 (density of silica constituting hollow silica particles 1) according to the formula: [1-(ρ / ρ0)]×100. (5) Shell thickness The shell thickness of hollow silica particles 1 was calculated using the following formula: The hollow diameter (inner diameter of hollow silica particles 1) was calculated using the volume average particle diameter R and porosity of hollow silica particles 1 using the formula: 4 / 3π×(R / 2) 3 ×Porosity=4 / 3π×(r / 2) 3The inner diameter r of the hollow silica particle 1 was calculated by the above equation. Formula: [Average particle size (outer diameter of hollow silica particle 1) - Hollow diameter (inner diameter of hollow silica particle 1)] / 2 (6) Shell ratio The shell ratio of hollow silica particles 1 was calculated from the volume average particle diameter R of hollow silica particles 1 and the inner diameter r of hollow silica particles 1 by the formula: shell ratio (%)=(r / R)×100.

[0268] Hollow silica particles 2: Hollow silica particles prepared by the following method (Method for preparing hollow silica particles 2) Hollow silica particles 2 were obtained under the same conditions as hollow silica particles 1, except that 2 g of polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer ("Pluronic F68" manufactured by ADEKA Corporation) and 2 g of sorbitan acid monooleate (Ionet S-80 manufactured by Sanyo Chemical Industries, Ltd.) were added to n-decane and the emulsion was high-pressure emulsified once at a pressure of 20 MPa using a high-pressure emulsifier (OMEGALAB manufactured by Ashizawa Finetech Co., Ltd.) to reduce the emulsion diameter to 2 μm, and the mixture was allowed to stand at room temperature for 48 hours. The physical properties of the obtained hollow silica particles 2 were measured by the above-mentioned methods. The results are shown in Table 1.

[0269] Hollow silica particles 3: Daiken Chemical Co., Ltd., DLSB-001-20SGCT, average particle size 0.35 μm The physical properties of the hollow silica particles 3 were measured by the methods described above. The results are shown in Table 1.

[0270] Hollow silica particles 4: SG Japan, SG-HS700PQH, average particle size 0.7 μm The physical properties of the hollow silica particles 4 were measured by the methods described above. The results are shown in Table 1.

[0271] Silane coupling agent: Silane coupling agent "X-12-1290" represented by the following formula (1), manufactured by Shin-Etsu Silicone Co., Ltd. (viscosity: approximately 180 mm 2 / s) [ka]

[0272] Polyether resin: a polyether resin represented by the following formula (2) prepared by the following preparation method: (Method for preparing polyether resin) In a four-neck flask, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (BisTMC) (37.2 g, 120 mmol) 1,1-bis(4-hydroxyphenyl)-nonane (BisP-DED) (9.9 g, 30 mmol), 4,6-dichloro-2-phenylpyrimidine (PhPym) (41.1 g, 183.3 mmol), and potassium carbonate (34.2 g, 247.5 mmol) were weighed out and N-methyl-2-pyrrolidone (225 g) was added. The mixture was reacted at 130 °C for 6 hours under a nitrogen atmosphere. After the reaction was completed, the mixture was diluted with N-methyl-2-pyrrolidone (1095 g). The salt was removed by filtration, and the resulting solution was poured into methanol (27 kg). The precipitated solid was filtered off and then recovered by filtration again with a small amount of methanol. The solid was then dried under reduced pressure at 120 °C for 12 hours in a vacuum dryer to obtain phenol-terminated polymer A (yield 85%, weight average molecular weight (Mw): 85,000, glass transition temperature (Tg): 196 °C). Next, 100 g of the terminal phenol polymer A, 15 g of a 50:50 mass ratio mixture of p-chloromethylstyrene and m-chloromethylstyrene (chloromethylstyrene: CMS, manufactured by Tokyo Chemical Industry Co., Ltd.), 0.62 g of tetra-n-butylammonium bromide as a phase transfer catalyst, and 200 g of toluene were charged into a 1-liter three-neck flask equipped with a temperature controller, a stirrer, a cooling device, and a dropping funnel, and stirred. The terminal phenol polymer A, chloromethylstyrene, and tetra-n-butylammonium bromide were stirred until they were dissolved in the toluene. The mixture was gradually heated until the liquid temperature reached 75°C. An aqueous solution of sodium hydroxide (10 g sodium hydroxide / 10 g water) was added dropwise to the solution over 20 minutes as an alkali metal hydroxide. The mixture was then stirred at 75°C for an additional 4 hours. The contents of the flask were then neutralized with 10% by mass hydrochloric acid, and a large amount of methanol was then added. This caused a precipitate to form in the liquid in the flask. That is, the product contained in the reaction solution in the flask was reprecipitated. The precipitate was then filtered, washed three times with a mixture of methanol and water in an 80:20 mass ratio, and then dried under reduced pressure at 80°C for 3 hours. In the obtained polyether resin represented by the following formula (2), m was about 60-100 and n was 15-25. [ka]

[0273] Styrene resin: a styrene resin represented by the following formula (3) prepared by the following preparation method: (Method for preparing styrene resin) 1.96 moles (55.1 g) of ethylene, 0.57 moles (59.5 g) of styrene 0.40 mol (52.1 g) of divinylbenzene, 0.02 mol (2.1 g) of ethylvinylbenzene, and 0.75 mol (76.6 g) of n-propyl acetate were charged into a reactor, and 30 mmol of triphenylcarbenium tetrakis(pentafluorophenyl)borate (trityl tetrakis(pentafluorophenyl)borate) was added at 70°C and reacted for 4 hours. After the polymerization reaction was terminated with aqueous sodium bicarbonate, the oil layer was washed three times with pure water and devolatilized under reduced pressure at 60°C to obtain a styrene resin. The number-average molecular weight (Mn) of the resulting styrene resin was 6,500, and the weight-average molecular weight (Mw) was 86,000. In the obtained polyether resin represented by the following formula (3), a was 12-20, b was 20-25, and c was 70-90. [ka]

[0274] Polybutadiene elastomer: Liquid polybutadiene, "Ricon 100" manufactured by Cray Valley

[0275] Modified polyphenylene ether resin: Terminal methacrylic group-modified polyphenylene ether represented by the following formula (4), "SA9000" manufactured by SABIC Innovative Plastics [ka]

[0276] Crosslinking agent: triallyl isocyanate (TAIC) manufactured by Mitsubishi Chemical Corporation

[0277] Maleimide resin: a resin represented by the following formula (5), "NE-X-9470S" manufactured by DIC Corporation [ka]

[0278] Epoxy resin Bisphenol F epoxy resin "830S" manufactured by DIC Corporation

[0279] Active ester hardener Active ester curing agent prepared by the following method (Method for preparing active ester curing agent) A flask equipped with a thermometer, dropping funnel, condenser, fractionating column, and stirrer was charged with 203.0 g of 1,3-benzenedicarboxylic acid dichloride (molar number of acid chloride groups: 2.0 mol) and 1,338 g of toluene. The system was then vacuum-purged with nitrogen to dissolve the reactants. Next, 96.5 g (0.67 mol) of α-naphthol and 219.5 g of dicyclopentadiene phenol resin (molar number of phenolic hydroxyl groups: 1.33 mol) were charged, and the system was vacuum-purged with nitrogen to dissolve the reactants. Subsequently, while purging with nitrogen gas, the system was maintained at 60°C or below, and 400 g of 20% aqueous sodium hydroxide solution was added dropwise over 3 hours. Stirring was continued under these conditions for 1.0 hour. After the reaction was completed, the mixture was allowed to stand, allowing the liquid to separate, and the aqueous layer was removed. Water was then added to the toluene phase containing the dissolved reactants, and the mixture was stirred and mixed for approximately 15 minutes. The mixture was then allowed to stand, allowing the liquid to separate, and the aqueous layer was removed. This procedure was repeated until the pH of the aqueous layer reached 7. The water was then removed by decanting, yielding an activated ester resin in the form of a toluene solution with a nonvolatile content of 65%. The structure of the resulting activated ester resin was confirmed to be R 1 and R 3 The active ester resin had a structure in which π was a hydrogen atom, Z was a naphthyl group, and l was 0. The average value k of the repeating units of the active ester resin was calculated from the reaction equivalent ratio and was in the range of 0.5 to 1.0. The obtained active ester resin specifically had a structure represented by the following chemical formula (6). In the following formula, the average value k of the repeating units was 0.5 to 1.0. [ka]

[0280] Coumarone resin: Indene-coumarone-styrene copolymer containing phenolic groups at the terminals (Nitto Chemical Co., Ltd., V-120S, mass average molecular weight: 950, hydroxyl value: 30 mg KOH / g)

[0281] Leveling agent: Polyacrylate compound "BYK-361N" manufactured by BYK-Chemie Polymerization initiator: 1,3-di[(t-butylperoxy)isopropyl]benzene "Perbutyl P" manufactured by NOF Corporation Curing accelerator: 2-phenyl-4-methylimidazole "2PZ-PW" manufactured by Shikoku Chemicals Corporation

[0282] (a) Electrical properties (dielectric constant Dk / dielectric loss tangent Df) A resin varnish was applied to one side of a 38 μm thick PET film using a comma coater so that the total thickness of the resin layer after drying would be 30 μm, and this was dried for 3 minutes in a drying device at 160°C to obtain a resin sheet (resin film with carrier) in which a resin film was laminated on the PET film. Next, four 30 μm thick resin films with a carrier were stacked on top of each other, and hot pressed with copper foil at 200°C and 0.5 kgf / mm 2 The resin film was cured by heating and pressing for 2 hours under the pressing conditions of 1.0 to 1.5 for 2 hours to obtain a laminate of the cured film and the copper foil. The copper foil of the obtained laminate was then removed by etching to obtain a cured film. The dielectric constant Dk / dielectric loss tangent Df of the cured film at 10 GHz was measured using a cavity resonator method.

[0283] (b) Storage modulus The storage modulus (GPa) was calculated at 30°C using a dynamic viscoelasticity device in accordance with JISC-6481 (DMA method). The sample used was the cured film prepared for the evaluation of electrical properties (a).

[0284] (c) Glass transition temperature (Tg) The measurements were performed in accordance with JISC-6481 (DMA method) using a dynamic viscoelasticity analyzer (TA Instruments Q800) at a temperature range of 0°C to 300°C and a heating rate of 5°C / min. The samples used were the cured films prepared for the evaluation of electrical properties (a).

[0285] (d) Coefficient of linear expansion (CTE) The thermal expansion coefficient was measured using a TMA (thermal mechanical analysis) device (TA Instruments, Q400) by preparing a 4 mm x 20 mm test piece and measuring the linear expansion coefficient (CTE) α1 during the second cycle of heating from 50 to 150°C under the conditions of a temperature range of 30 to 300°C, 10°C / min, and a load of 5 g. The sample used was the cured film prepared for the evaluation of electrical properties (a).

[0286] (e) Peel strength The peel strength was measured in accordance with JISC-6481. The sample used was the laminate prepared for the evaluation of electrical properties (a).

[0287] [Table 1]

[0288] [Table 2]

[0289] The resin compositions for forming circuit boards of the examples provided cured products with low dielectric constants, low dielectric loss tangents, and excellent adhesion to copper foil. Furthermore, it was revealed that the linear expansion coefficient can be reduced by using hollow silica particles in combination with silica particles. [Explanation of symbols]

[0290] 10 Resin film with carrier 12 Resin film with carrier 20 insulating film 30 primer layer 40 Carrier substrate 100 Core Layer 102 Insulating layer 104 Beer Hall 106 Electroless metal plating film 108 Metal layer 200 Semiconductor Packages 202 Electroless metal plating film 204 Resist 206 Opening 208 Electrolytic metal plating layer 210 Opening 220 metal layer 230 Solder resist layer 240 Semiconductor elements 250 solder bumps 260 Encapsulant layer

Claims

1. Hollow silica particles (A), Resin (B), A resin composition for forming a circuit board, comprising: The resin composition for forming a circuit board, wherein the hollow silica particles (A) have a pressure at which the pore volume reaches a maximum value as measured by mercury intrusion porosimetry of 100 MPa or more.

2. 2. The resin composition for forming a circuit board according to claim 1, wherein the weight loss rate of the hollow silica particles (A) calculated under the following measurement conditions is 5.0% or less. (Measurement conditions) Measurement equipment: TG-DTA (Thermography-Differential Thermal Analysis) Atmosphere: atmospheric Measurement temperature: The temperature is increased from 30°C to 800°C at a rate of 10°C / min, and maintained at 800°C for 30 minutes.

3. 2. The resin composition for forming a circuit board according to claim 1, wherein the hollow silica particles (A) have a void ratio of 60% by volume or more and 90% by volume or less.

4. 2. The resin composition for forming a circuit board according to claim 1, wherein the hollow silica particles (A) have an average particle size of 0.1 μm or more and 3.0 μm or less.

5. 2. The resin composition for forming a circuit board according to claim 1, wherein the shell thickness of the hollow silica particles (A) is 0.01 μm or more and 0.20 μm or less.

6. The resin composition for forming a circuit board according to claim 1, wherein the hollow silica particles (A) have a shell ratio of 1% or more and 50% or less.

7. 2. The resin composition for forming a circuit board according to claim 1, wherein the resin (B) comprises one or more resins selected from the group consisting of polyphenylene ether resins, maleimide resins, coumarone resins, polyether resins, styrene resins, cyanate resins, and epoxy resins.

8. The resin (B) contains an epoxy resin, The resin composition for forming a circuit board according to claim 1 , further comprising an active ester curing agent (C).

9. The resin composition for forming a circuit board according to claim 8 , wherein the active ester curing agent (C) has a structure represented by the following general formula (1): 【Chemical 1】 In general formula (1), A represents a substituted or unsubstituted arylene group linked via an aliphatic cyclic hydrocarbon group, and Ar′ represents a substituted or unsubstituted aryl group. B is a structure represented by the following general formula (B): 【Chemistry 2】 (In general formula (B), Ar is a substituted or unsubstituted arylene group; Y is a single bond, a substituted or unsubstituted linear alkylene group having 1 to 6 carbon atoms, or a substituted or unsubstituted cyclic alkylene group having 3 to 6 carbon atoms, a substituted or unsubstituted divalent aromatic hydrocarbon group, an ether bond, a carbonyl group, a carbonyloxy group, a sulfide group, or a sulfone group; and n is an integer of 0 to 4.) k is the average value of the repeating units and is in the range of 0.25 to 3.

5.

10. The resin composition for forming a circuit board according to claim 1 , further comprising silica particles (D) (excluding the hollow silica particles (A)).

11. The resin composition for forming a circuit board according to claim 1, The resin composition for forming a circuit board, wherein a dielectric loss tangent Df at 10 GHz of a cured product of the resin composition for forming a circuit board is 0.0032 or less.

12. The resin composition for forming a circuit board according to claim 1, The resin composition for forming a circuit board, wherein a cured product of the resin composition for forming a circuit board has a dielectric constant Dk at 10 GHz of 1.8 or more and 2.8 or less.

13. The resin composition for forming a circuit board according to claim 1, The resin composition for forming a circuit board, wherein the linear expansion coefficient of a cured product of the resin composition for forming a circuit board is 80 ppm / °C or more and 130 ppm / °C or less.

14. The resin composition for forming a circuit board according to claim 1, A resin composition for forming a circuit board, wherein a cured product of the resin composition for forming a circuit board has a peel strength from copper foil of 0.3 kN / m or more.

15. Hollow silica particles (A), Resin (B), A resin composition for forming a circuit board, comprising: The resin composition for forming a circuit board, wherein the weight loss rate of the hollow silica particles (A) calculated under the following measurement conditions is 5.0% or less. (Measurement conditions) Measurement equipment: TG-DTA (Thermography-Differential Thermal Analysis) Atmosphere: atmospheric Measurement temperature: The temperature is increased from 30°C to 800°C at a rate of 10°C / min, and maintained at 800°C for 30 minutes.

16. A resin sheet comprising the resin composition for forming a circuit board according to any one of claims 1 to 15.

17. A carrier substrate; A resin film with a carrier, comprising: a resin sheet formed on the carrier base and comprising the resin composition for forming a circuit board according to any one of claims 1 to 15.

18. A prepreg obtained by impregnating a fiber substrate with the resin composition for forming a circuit board according to any one of claims 1 to 15.

19. A laminate comprising the prepreg according to claim 18 and a metal layer disposed on at least one surface of the prepreg.

20. A printed wiring board comprising an insulating layer formed from a cured product of the resin composition for forming a circuit board according to any one of claims 1 to 15.

21. The printed wiring board according to claim 20; a semiconductor element mounted on a circuit layer of the printed wiring board or embedded in the printed wiring board.

22. A wiring board comprising a conductor layer on a dielectric substrate formed from a cured product of the resin composition for forming a circuit board according to any one of claims 1 to 15.

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