WO2025013394A1 - Resin material, cured article, and multilayer printed wiring board - Google Patents

Abstract

Provided is a resin material capable of increasing a glass transition temperature of a cured article, reducing a dielectric constant and a dielectric loss tangent of a cured article, and hardly causing cracking of hollow inorganic particles even when subjected to ultrasonic treatment.　A resin material according to the present invention contains a maleimide compound (A) and hollow inorganic particles (B), and the hollow inorganic particles (B) have a BET specific surface area satisfying formula (1).　(1): 1.05×(3/rd)<S<2.00×(3/rd), wherein S is the BET specific surface area (m²/g) of the hollow inorganic particles (B); r is the average particle radius (μm) of the hollow inorganic particles (B); and d is the true density (g/cm³) of the hollow inorganic particles (B).

Description

Resin materials, cured products and multi-layer printed wiring boards

The present invention relates to a resin material containing a maleimide compound. The present invention also relates to a cured product of the above resin material. Furthermore, the present invention also relates to a multilayer printed wiring board using the above resin material.

Traditionally, various resin materials have been used to obtain electronic components such as semiconductor devices, laminates, and printed wiring boards. For example, in multilayer printed wiring boards, resin materials are used to form insulating layers for insulating between internal layers and to form insulating layers located on the surface. Wiring, which is generally metal, is laminated on the surface of the insulating layer. Also, film-like resin materials (resin films) are sometimes used to form the insulating layers. The resin materials are used as insulating materials for multilayer printed wiring boards, including build-up films.

Patent Document 1 below discloses a resin composition containing (A) epoxy resin, (B) hardener, (C) hollow silica, and (D) fused silica. In this resin composition, when the non-volatile components in the resin composition are taken as 100% by mass, the content of (C) hollow silica is 5 to 22% by mass, and the total content of (C) hollow silica and (D) fused silica is 50 to 70% by mass.

Patent Document 2 below discloses a resin composition that contains a thermosetting resin (A) and a filler (B), where the filler (B) contains hollow particles (b) that satisfy a specific formula and have an average particle size of 0.01 to 10 μm.

JP 2013-173841 A WO2019/230661A1

As described in Patent Documents 1 and 2 above, a resin material containing a thermosetting compound and hollow inorganic particles is known. By using hollow inorganic particles, the dielectric constant and dielectric tangent of the cured resin material can be lowered to a certain degree.

However, with conventional resin materials that contain a thermosetting compound and hollow inorganic particles, the glass transition temperature of the cured product may not be sufficiently high.

When manufacturing electronic components such as printed wiring boards, wiring may be formed by laminating a resin material onto a substrate, heating, desmearing, or ultrasonic treatment. However, when using conventional resin materials containing hollow inorganic particles, the hollow inorganic particles may crack during these treatments. Among these treatments, hollow inorganic particles are particularly susceptible to cracking during ultrasonic treatment. When hollow inorganic particles crack, the chemical solution used to form the wiring seeps into the cracked area, increasing the amount of copper seeping in, which can cause a short circuit between the wires.

The object of the present invention is to provide a resin material that can increase the glass transition temperature of the cured product, can reduce the dielectric constant and dielectric tangent of the cured product, and has hollow inorganic particles that are less likely to break even when subjected to ultrasonic treatment. Another object of the present invention is to provide a cured product of the above resin material. Still another object of the present invention is to provide a multilayer printed wiring board using the above resin material.

　This specification discloses the following resin material, cured product, and multilayer printed wiring board.

Item 1. A resin material comprising a maleimide compound (A) and hollow inorganic particles (B), the BET specific surface area of the hollow inorganic particles (B) satisfying the following formula (1):

1.05×(3/rd)<S<2.00×(3/rd)...(1)
S: BET specific surface area (m ² /g) of hollow inorganic particles (B)
r: average particle radius of hollow inorganic particles (B) (μm)
d: true density of hollow inorganic particles (B) (g/cm ³ )

Item 2. The resin material according to item 1, in which the content of the maleimide compound (A) is 20% by weight or more and 70% by weight or less, based on 100% by weight of the components excluding the solvent in the resin material.

Item 3. The resin material according to item 1 or 2, wherein the maleimide compound (A) has a skeleton derived from dimer diamine.

Item 4. The resin material according to any one of items 1 to 3, wherein the maleimide compound (A) has a skeleton derived from a dimer diamine and a skeleton derived from a diamine compound having an alicyclic skeleton other than a dimer diamine.

Item 5. The resin material according to Item 4, wherein the diamine compound having an alicyclic skeleton other than the dimer diamine is tricyclodecane diamine, norbornane diamine, or isophorone diamine.

Item 6. The resin material according to any one of items 1 to 5, in which the content of the hollow inorganic particles (B) is 60% by weight or less based on 100% by weight of the components excluding the solvent in the resin material.

Item 7. The resin material according to any one of items 1 to 6, further comprising solid inorganic particles (C).

Item 8. The resin material according to any one of items 1 to 7, further comprising a thermosetting compound (D) having a functional group capable of reacting with a maleimide group.

Item 9. The resin material according to Item 8, wherein the thermosetting compound (D) includes a thermosetting compound having an epoxy group, a vinyl group, a styryl group, a benzoxazine group, a cyanate group, an allyl group, a methacryloyl group, or an acryloyl group.

Item 10. A resin material according to any one of items 1 to 9, in which when the resin material is heated at 180°C for 30 minutes and then heated at 200°C for 60 minutes to obtain a cured product of the resin material, the resulting cured product has a dielectric constant of 2.5 or less at 10 GHz.

Item 11. The resin material according to any one of items 1 to 10, which is a resin film.

Item 12. The resin material according to any one of items 1 to 11, which is used to form an insulating layer in a multilayer printed wiring board.

Item 13. A cured product of a resin material, the resin material being the resin material described in any one of items 1 to 12.

Item 14. A multilayer printed wiring board comprising a circuit board, a plurality of insulating layers disposed on a surface of the circuit board, and a metal layer disposed between the plurality of insulating layers, at least one of the plurality of insulating layers being a cured product of the resin material described in any one of items 1 to 12.

The resin material according to the present invention contains a maleimide compound (A) and hollow inorganic particles (B), and the BET specific surface area of the hollow inorganic particles (B) satisfies a specific formula (1). Since the resin material according to the present invention has the above-mentioned configuration, the glass transition temperature of the cured product can be increased, the dielectric constant and dielectric tangent of the cured product can be reduced, and the hollow inorganic particles are less likely to break even when subjected to ultrasonic treatment.

FIG. 1 is a cross-sectional view showing a multilayer printed wiring board using a resin material according to one embodiment of the present invention. FIG. 2 is a diagram for explaining a method for calculating the plating penetration amount evaluated in the examples.

The details of the present invention are explained below.

(Resin material)
The resin material according to the present invention contains a maleimide compound (A) and hollow inorganic particles (B), and the BET specific surface area of the hollow inorganic particles (B) satisfies the following formula (1).

1.05×(3/rd)<S<2.00×(3/rd)...(1)
S: BET specific surface area (m ² /g) of hollow inorganic particles (B)
r: average particle radius of hollow inorganic particles (B) (μm)
d: true density of hollow inorganic particles (B) (g/cm ³ )

The resin material according to the present invention has the above-mentioned configuration, so that the glass transition temperature of the cured product can be increased, the dielectric constant and dielectric tangent of the cured product can be decreased, and the hollow inorganic particles are less likely to break even when subjected to ultrasonic treatment.

The resin material according to the present invention can maintain low dielectric constant and dielectric tangent of the cured product before and after ultrasonic treatment.

In conventional resin materials containing hollow inorganic particles, the hollow inorganic particles are prone to cracking even when laminated. In contrast, in the resin material of the present invention, the hollow inorganic particles are less likely to crack even when laminated. Therefore, with the resin material of the present invention, the dielectric constant and dielectric tangent of the cured product can be reduced even when used in a laminated state.

In addition, the hollow inorganic particles in the resin material of the present invention are less likely to crack, so short circuits between wiring can be effectively prevented.

The resin material according to the present invention may be a resin composition or a resin film. The resin composition has fluidity. The resin composition may be in a paste form. The paste form includes a liquid form. Since this has excellent handleability, the resin material according to the present invention is preferably a resin film.

The resin material according to the present invention is preferably a thermosetting resin material. When the resin material is a resin film, the resin film is preferably a thermosetting resin film.

In the following description, "100% by weight of components in the resin material excluding the solvent" means 100% by weight of components in the resin material excluding the solvent when the resin material contains a solvent, and means 100% by weight of the resin material when the resin material does not contain a solvent. "100% by weight of components in the resin material excluding hollow inorganic particles (B), solid inorganic particles (C) and solvent" means 100% by weight of components in the resin material excluding hollow inorganic particles (B), solid inorganic particles (C) and solvent when the resin material contains hollow inorganic particles (B), solid inorganic particles (C) and solvent. "100% by weight of components in the resin material excluding hollow inorganic particles (B), solid inorganic particles (C) and solvent" means 100% by weight of components in the resin material excluding hollow inorganic particles (B), solid inorganic particles (C) and solvent when the resin material contains hollow inorganic particles (B) and solvent but does not contain solid inorganic particles (C). "100% by weight of the components in the resin material excluding hollow inorganic particles (B), solid inorganic particles (C) and solvent" means 100% by weight of the components in the resin material excluding the hollow inorganic particles (B) when the resin material contains hollow inorganic particles (B) but does not contain solid inorganic particles (C) and solvent.

　Below, we will explain the details of each component used in the resin material according to the present invention, as well as applications of the resin material according to the present invention.

[Maleimide compound (A)]
The resin material contains a maleimide compound (A). As the maleimide compound (A), a conventionally known maleimide compound can be used. The maleimide compound (A) may be used alone or in combination of two or more kinds.

The maleimide compound (A) may have one maleimide group, two maleimide groups, two or more maleimide groups, three or more maleimide groups, four or more maleimide groups, 800 or less maleimide groups, 500 or less maleimide groups, or 300 or less maleimide groups.

From the viewpoint of further reducing the dielectric constant and dielectric tangent of the cured product, the maleimide compound (A) preferably contains a maleimide compound having two maleimide groups, and is more preferably a maleimide compound having two maleimide groups. Therefore, the maleimide compound (A) preferably contains a bismaleimide compound, and is more preferably a bismaleimide compound.

The maleimide compound (A) preferably has an aliphatic skeleton or an alicyclic skeleton, and more preferably has an aliphatic skeleton and an alicyclic skeleton. In this case, the effects of the present invention can be more effectively exhibited. In addition, the desmear property and plating peel strength can be improved.

The aliphatic skeleton may be a chain aliphatic skeleton, for example, a saturated hydrocarbon group or an unsaturated hydrocarbon group. The aliphatic skeleton is preferably an aliphatic skeleton having 4 or more carbon atoms. The number of carbon atoms in an aliphatic skeleton having 4 or more carbon atoms is preferably 5 or more, more preferably 6 or more, even more preferably 7 or more, preferably 60 or less, more preferably 50 or less, even more preferably 40 or less. More specifically, the aliphatic skeleton may be an alkyl group having 4 to 60 carbon atoms (preferably an alkyl group having 6 to 40 carbon atoms). The maleimide compound (A) may have only one type of the aliphatic skeleton, or may have two or more types.

The alicyclic skeleton may include a monocycloalkane ring, a bicycloalkane ring, a tricycloalkane ring, a tetracycloalkane ring, and a dicyclopentadiene ring. The maleimide compound (A) may have only one type of the alicyclic skeleton, or two or more types.

From the viewpoint of further increasing the glass transition temperature of the cured product, it is preferable that the maleimide compound (A) has an aromatic skeleton.

The aromatic skeleton includes a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a tetracene ring, a chrysene ring, a triphenylene ring, a tetraphene ring, a pyrene ring, a pentacene ring, a picene ring, and a perylene ring. The maleimide compound (A) may have only one type of the aromatic skeleton, or two or more types.

The maleimide compound (A) preferably has a skeleton derived from dimer diamine. Since a maleimide compound having a skeleton derived from dimer diamine has an aliphatic skeleton and an alicyclic skeleton, the use of this maleimide compound can further reduce the dielectric constant and dielectric tangent of the cured product.

Examples of the above dimer diamine (commercially available dimer diamine) include "VERSAMINE 551" (3,4-bis(1-aminoheptyl)-6-hexyl-5-(1-octenyl)cyclohexene) manufactured by BASF Japan, "VERSAMINE 552" (hydrogenated product of VERSAMINE 551) manufactured by Cognix Japan, and "PRIAMINE 1075" and "PRIAMINE 1074" manufactured by Croda Japan. Only one type of the above dimer diamine may be used, or two or more types may be used in combination.

It is preferable that the maleimide compound (A) has a skeleton derived from a dimer diamine and a skeleton derived from a second diamine compound other than the dimer diamine. In this case, the effects of the present invention can be more effectively achieved.

The second diamine compound may be tricyclodecanediamine, norbornanediamine, isophoronediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornane, 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.02,6]decane, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), 1,4-diamino Examples of the second diamine compound include butane, 1,10-diaminodecane, 1,12-diaminododecane, 1,7-diaminoheptane, 1,6-diaminohexane, 1,5-diaminopentane, 1,8-diaminooctane, 1,3-diaminopropane, 1,11-diaminoundecane, 2-methyl-1,5-diaminopentane, 1,1-bis(4-aminophenyl)cyclohexane, 2,7-diaminofluorene, 4,4'-ethylenedianiline, 4,4'-methylenebis(2,6-diethylaniline), and 4,4'-methylenebis(2-ethyl-6-methylaniline). Only one type of the second diamine compound may be used, or two or more types may be used in combination.

The second diamine compound may or may not have an aliphatic skeleton. The second diamine compound may or may not have an alicyclic skeleton. The second diamine compound may or may not have an aromatic skeleton.

The second diamine compound preferably contains a diamine compound having an alicyclic skeleton other than dimer diamine. The maleimide compound (A) preferably has a skeleton derived from dimer diamine and a skeleton derived from a diamine compound having an alicyclic skeleton other than dimer diamine. In this case, the effect of the present invention can be exerted even more effectively.

The diamine compound having an alicyclic skeleton other than the above dimer diamine is preferably tricyclodecane diamine, norbornane diamine, or isophorone diamine. In this case, the effects of the present invention can be more effectively exerted.

The maleimide compound (A) preferably has a skeleton derived from an acid dianhydride, more preferably has a skeleton derived from a reaction product of a diamine compound and an acid dianhydride, and even more preferably has a skeleton derived from a reaction product of a dimer diamine and an acid dianhydride.

Examples of the acid dianhydride include tetracarboxylic dianhydrides. Examples of the tetracarboxylic dianhydrides include pyromellitic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3',4,4'-biphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3',4,4'-tetraphenylsilane tetracarboxylic dianhydride, 1,2,3,4-furan tetracarboxylic dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylsulfonate, and 4,4'-bis(3,4-dicarboxyphenoxy)diphenylsulfonate. Examples of the dianhydride include 4,4'-bis(3,4-dicarboxyphenoxy)diphenylsulfone dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylpropane dianhydride, 3,3',4,4'-perfluoroisopropylidenediphthalic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, bis(phthalic acid)phenylphosphine oxide dianhydride, p-phenylene-bis(triphenylphthalic acid) dianhydride, m-phenylene-bis(triphenylphthalic acid) dianhydride, bis(triphenylphthalic acid)-4,4'-diphenylether dianhydride, and bis(triphenylphthalic acid)-4,4'-diphenylmethane dianhydride. The above dianhydrides may be used alone or in combination of two or more.

The molecular weight of the maleimide compound (A) is preferably 200 or more, more preferably 500 or more, even more preferably 1,000 or more, and preferably 200,000 or less, more preferably 100,000 or less, even more preferably 50,000 or less. When the molecular weight is equal to or greater than the lower limit and equal to or less than the upper limit, a resin material with high fluidity is easily obtained when forming the insulating layer, and good lamination properties can be obtained. Furthermore, because good lamination properties can be obtained, the plating peel strength of the cured product can be further increased.

The molecular weight of the maleimide compound (A) means the molecular weight that can be calculated from the structural formula when the maleimide compound (A) is not a polymer and when the structural formula of the maleimide compound (A) can be identified. When the maleimide compound (A) is a polymer, it means the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

Commercially available maleimide compounds (A) include "NE-X-9470S" manufactured by DIC Corporation, "MIR-5000-60T" and "MIR-3000-70MT" manufactured by Nippon Kayaku Co., Ltd., "BMI-3000J", "BMI-2500", "BMI-1500" and "BMI-689" manufactured by Designer Molecules Inc., and "BMI", "BMI-70" and "BMI-80" manufactured by Kei-I Chemicals Co., Ltd.

The maleimide compound (A) can also be obtained by reacting an acid dianhydride, such as a tetracarboxylic dianhydride, with a diamine compound to obtain a reaction product, and then reacting the reaction product with maleic anhydride.

The content of the maleimide compound (A) in 100% by weight of the components excluding the solvent in the resin material is preferably 20% by weight or more, more preferably 25% by weight or more, even more preferably 30% by weight or more, preferably 70% by weight or less, more preferably 65% by weight or less, and even more preferably 60% by weight or less. When the content of the maleimide compound (A) is equal to or more than the above lower limit and equal to or less than the above upper limit, the lamination properties can be further improved. In addition, the surface roughness after the roughening treatment can be further reduced, and the plating peel strength of the cured product can be further increased.

[Hollow inorganic particles (B)]
The resin material contains hollow inorganic particles (B). The hollow inorganic particles (B) may be used alone or in combination of two or more kinds.

The hollow inorganic particles (B) are inorganic particles having a hollow space. The hollow inorganic particles (B) have a hollow space and an outer shell surrounding the hollow space. The number of the hollow spaces surrounded by the outer shell is usually one.

The hollow inorganic particles (B) are formed from an inorganic material. More specifically, the outer shell of the hollow inorganic particles (B) is formed from an inorganic material.

Inorganic substances that form the hollow inorganic particles (B) include silica, aluminosilicate, silsesquioxane, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. The above inorganic substances may be used alone or in combination of two or more.

The inorganic material forming the hollow inorganic particles (B) preferably contains silica, aluminosilicate, or silsesquioxane, more preferably contains silica or aluminosilicate, even more preferably contains silica, and particularly preferably is silica. The hollow inorganic particles (B) preferably contain hollow silica particles, hollow aluminosilicate particles, or hollow silsesquioxane particles, more preferably contains hollow silica particles or hollow aluminosilicate particles, even more preferably contains hollow silica particles, and particularly preferably is hollow silica particles. In this case, the dielectric constant and dielectric tangent of the cured product of the resin material can be further reduced.

From the viewpoint of exerting the effects of the present invention, the BET specific surface area of the hollow inorganic particles (B) satisfies the following formula (1). In the following formula (1), (3/rd) means the theoretical value of the specific surface area, i.e., surface area/(volume x true density). The inventors have found that the effects of the present invention can be exerted by using hollow inorganic particles whose BET specific surface area is appropriately larger than the theoretical value of the specific surface area.

1.05×(3/rd)<S<2.00×(3/rd)...(1)
S: BET specific surface area (m ² /g) of hollow inorganic particles (B)
r: average particle radius of hollow inorganic particles (B) (μm)
d: true density of hollow inorganic particles (B) (g/cm ³ )

The BET specific surface area (S) of the hollow inorganic particles (B) is preferably 1 ^m2 /g or more, more preferably 5 ^m2 /g or more, and preferably 200 ^m2 /g or less, more preferably 150 ^m2 /g or less. When the BET specific surface area (S) is equal to or more than the lower limit and equal to or less than the upper limit, the dispersibility of the hollow inorganic particles (B) in the resin material can be further improved.

The BET specific surface area (S) of the hollow inorganic particles (B) can be measured using a specific surface area/pore distribution measuring device (e.g., "NOVA4200e" manufactured by Quantachrome Instruments).

The average particle radius (r) of the hollow inorganic particles (B) is preferably 50 nm or more, more preferably 75 nm or more, even more preferably 100 nm or more, and preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 2 μm or less. When the average particle radius (r) is equal to or greater than the lower limit and equal to or less than the upper limit, the surface roughness after etching can be reduced and the plating peel strength can be increased, and the adhesion between the insulating layer and the metal layer can be further improved. In addition, short circuits between wiring can be further suppressed.

The average particle radius (r) of hollow inorganic particles (B) is calculated by multiplying the average particle diameter of hollow inorganic particles (B) by 0.5. The value of the median diameter (d50) at 50% is used as the average particle diameter of hollow inorganic particles (B). The average particle diameter of hollow inorganic particles (B) can be measured using a particle size distribution measuring device that uses a laser diffraction scattering method. Note that when hollow inorganic particles (B) are agglomerated particles, the average particle diameter of hollow inorganic particles (B) means the primary particle diameter.

The true density (d) of the hollow inorganic particles (B) is preferably 0.2 g/ ^cm3 or more, more preferably 0.3 g/ ^cm3 or more, and preferably 2 g/cm3 or ^less , more preferably 1.5 g/cm3 ^or less. When the true density (d) is equal to or more than the lower limit and equal to or less than the upper limit, the dielectric constant and dielectric tangent of the cured product can be further reduced. In addition, the strength of the hollow inorganic particles (B) can be further increased.

The true density (d) of the hollow inorganic particles (B) can be measured using a true density measuring device (e.g., "Ultrapyc1200e" manufactured by QUANTACROME).

The shape of the hollow inorganic particles (B) is not particularly limited, but it is preferable that they are spherical. In this case, the surface roughness of the cured product is effectively reduced, and the adhesive strength between the cured product and the metal layer is effectively increased. When the hollow inorganic particles (B) are spherical, the aspect ratio of the hollow inorganic particles (B) is preferably 1 or more, preferably 2 or less, and more preferably 1.5 or less.

The number of holes (number of hollows) contained inside the hollow inorganic particle (B) is not particularly limited, but it is preferable that the number is one.

The porosity of the hollow inorganic particles (B) is preferably 20% by volume or more, more preferably 30% by volume or more, even more preferably 40% by volume or more, and preferably 90% by volume or less, more preferably 85% by volume or less, and even more preferably 80% by volume or less. If the porosity is equal to or greater than the lower limit and equal to or less than the upper limit, the dielectric constant and dielectric tangent of the cured product of the resin material can be further reduced.

When the number of holes (number of hollows) contained inside hollow inorganic particles (B) is one, the porosity can be calculated as follows. Photograph hollow inorganic particles (B) using a transmission electron microscope (TEM). From the obtained micrograph, the particle diameters of 50 arbitrary hollow inorganic particles (B) are measured, and the average value is taken as the average particle diameter (X). In addition, hollow inorganic particles (B) are cut in half, and the cut hollow inorganic particles (B) are photographed using a transmission electron microscope (TEM). From the obtained micrograph, the diameters of the cavities of the cut surfaces of 50 arbitrary cut hollow inorganic particles (B) are measured, and the average value is taken as the average diameter of the cavities (Y). Calculate the porosity using the following formula.

Porosity (volume %)=(Y ³ /X ³ )×100
X: Average particle diameter (X)
Y: average diameter of the cavity (Y)

When the number of holes (number of hollows) contained inside the hollow inorganic particles (B) is 2 or more, the above porosity can also be calculated using a transmission electron microscope (TEM) from the volume of the hollow inorganic particles (B) calculated from the particle diameter of the hollow inorganic particles (B) and the volume of the hollow parts calculated from the diameter of the hollow parts.

The hollow inorganic particles (B) are preferably surface-treated hollow inorganic particles, and more preferably surface-treated with a coupling agent. By surface-treating the hollow inorganic particles (B), the surface roughness of the cured product is further reduced, and the adhesive strength between the cured product and the metal layer is further increased. Furthermore, by surface-treating the hollow inorganic particles (B), finer wiring can be formed on the surface of the cured product, and better inter-wiring insulation reliability and inter-layer insulation reliability can be imparted to the cured product.

The above-mentioned coupling agents include silane coupling agents, titanium coupling agents, and aluminum coupling agents. The above-mentioned silane coupling agents include methacrylsilane, acrylic silane, phenylaminosilane, phenylsilane, imidazole silane, vinyl silane, alkylaminosilane, and epoxy silane.

The hollow inorganic particles (B) are preferably hollow inorganic particles that have been surface-treated with a silane coupling agent, and more preferably hollow inorganic particles that have been surface-treated with vinyl silane, phenylamino silane, or phenyl silane. In this case, the lamination properties can be further improved. In addition, because the lamination properties can be improved, the plating peel strength of the cured product can be further increased.

The content of hollow inorganic particles (B) in 100% by weight of the components excluding the solvent in the resin material is preferably 5% by weight or more, more preferably 10% by weight or more, even more preferably 15% by weight or more, preferably 60% by weight or less, more preferably 55% by weight or less, and even more preferably 50% by weight or less. When the content of hollow inorganic particles (B) is equal to or more than the lower limit, the dielectric constant and dielectric tangent of the cured product of the resin material can be further reduced. In addition, the thermal dimensional stability can be improved, and warping of the cured product can be effectively suppressed. When the content of hollow inorganic particles (B) is equal to or more than the lower limit and equal to or less than the upper limit, the surface roughness of the cured product can be further reduced, and short circuits between wirings can be further suppressed, so that even finer wiring can be formed on the surface of the cured product. Furthermore, with this content of hollow inorganic particles (B), it is possible to lower the thermal expansion coefficient of the cured product and at the same time improve smear removal properties.

[Solid inorganic particles (C)]
The resin material may contain solid inorganic particles (C). The solid inorganic particles (C) may be used alone or in combination of two or more kinds.

Solid inorganic particles (C) are inorganic particles that do not have hollow spaces.

Examples of solid inorganic particles (C) include solid silica particles, solid talc particles, solid clay particles, solid mica particles, solid hydrotalcite particles, solid alumina particles, solid magnesium oxide particles, solid aluminum hydroxide particles, solid aluminum nitride particles, and solid boron nitride particles.

From the viewpoint of reducing the surface roughness of the cured product, further increasing the adhesive strength between the cured product and the metal layer, forming finer wiring on the surface of the cured product, and imparting better insulation reliability to the cured product, the solid inorganic particles (C) are preferably solid silica particles or solid alumina particles, and more preferably solid silica particles.

The average particle size of the solid inorganic particles (C) is preferably 50 nm or more, more preferably 100 nm or more, even more preferably 500 nm or more, and preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less. When the average particle size of the solid inorganic particles (C) is equal to or greater than the above lower limit and equal to or less than the above upper limit, the surface roughness after etching can be reduced and the plating peel strength can be increased, and the adhesion between the insulating layer and the metal layer can be further improved.

The median diameter (d50) at 50% is used as the average particle size of the solid inorganic particles (C). The above average particle size can be measured using a particle size distribution measuring device that uses a laser diffraction scattering method.

The shape of the solid inorganic particles (C) is not particularly limited, but it is preferable that they are spherical. In this case, the surface roughness of the surface of the cured product is effectively reduced, and the adhesive strength between the cured product and the metal layer is effectively increased. When the solid inorganic particles (C) are spherical, the aspect ratio of the solid inorganic particles (C) is preferably 1 or more, preferably 2 or less, and more preferably 1.5 or less.

The solid inorganic particles (C) are preferably surface-treated, more preferably surface-treated with a coupling agent, and even more preferably surface-treated with a silane coupling agent. By surface-treating the solid inorganic particles (C), the surface roughness of the cured product is further reduced, and the adhesive strength between the cured product and the metal layer is further increased. Furthermore, by surface-treating the solid inorganic particles (C), finer wiring can be formed on the surface of the cured product, and better inter-wiring insulation reliability and inter-layer insulation reliability can be imparted to the cured product.

The above-mentioned coupling agents include silane coupling agents, titanium coupling agents, and aluminum coupling agents. The above-mentioned silane coupling agents include methacrylsilane, acrylic silane, aminosilane, imidazole silane, vinyl silane, and epoxy silane.

The content of the solid inorganic particles (C) in the resin material is preferably 1% by weight or more, more preferably 5% by weight or more, preferably 75% by weight or less, more preferably 70% by weight or less, and even more preferably 65% by weight or less, based on 100% by weight of the components excluding the solvent. If the content of the solid inorganic particles (C) is equal to or greater than the lower limit, the dielectric constant and dielectric tangent of the cured product of the resin material can be further reduced. In addition, the thermal dimensional stability can be improved, and warping of the cured product can be effectively suppressed. If the content of the solid inorganic particles (C) is equal to or greater than the lower limit and equal to or less than the upper limit, the surface roughness of the cured product can be further reduced, and finer wiring can be formed on the surface of the cured product. Furthermore, with this content of the solid inorganic particles (C), it is possible to lower the thermal expansion coefficient of the cured product and at the same time improve the smear removal properties.

[Thermosetting compound (D) having a functional group capable of reacting with a maleimide group]
The resin material preferably contains a thermosetting compound (D) having a functional group capable of reacting with a maleimide group. The thermosetting compound (D) is different from a maleimide compound. The thermosetting compound (D) does not have a maleimide group. The thermosetting compound (D) has a functional group capable of reacting with a maleimide group. As the thermosetting compound (D), a conventionally known thermosetting compound can be used. Only one type of the thermosetting compound (D) may be used, or two or more types may be used in combination.

Thermosetting compound (D) preferably contains a thermosetting compound having an epoxy group, a vinyl group, a styryl group, a benzoxazine group, a cyanate group, an allyl group, a methacryloyl group, or an acryloyl group. It is more preferable that the thermosetting compound (D) contains a thermosetting compound having an epoxy group, a vinyl group, a styryl group, a benzoxazine group, a cyanate group, an allyl group, or a methacryloyl group. In this case, the effects of the present invention can be exerted even more effectively.

The molecular weight of the thermosetting compound (D) is preferably 100 or more, more preferably 200 or more, even more preferably 300 or more, and preferably 200,000 or less, more preferably 100,000 or less, even more preferably 50,000 or less. If the molecular weight is equal to or greater than the lower limit and equal to or less than the upper limit, a resin material with high fluidity is easily obtained when forming the insulating layer, and good lamination properties can be achieved. Furthermore, because good lamination properties can be achieved, the plating peel strength of the cured product can be further increased.

The molecular weight of the thermosetting compound (D) means the molecular weight that can be calculated from the structural formula when the thermosetting compound (D) is not a polymer and when the structural formula of the thermosetting compound (D) can be identified. When the thermosetting compound (D) is a polymer, it means the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

The content of the thermosetting compound (D) in 100% by weight of the components excluding the solvent in the resin material is preferably 1% by weight or more, more preferably 3% by weight or more, and preferably 60% by weight or less, more preferably 50% by weight or less. When the content of the thermosetting compound (D) is equal to or more than the above lower limit and equal to or less than the above upper limit, the dielectric constant and dielectric tangent of the cured product can be further reduced, and the thermal dimensional stability of the cured product can be further improved.

The content of the thermosetting compound (D) in 100% by weight of the components in the resin material excluding the hollow inorganic particles (B), solid inorganic particles (C) and solvent is preferably 5% by weight or more, more preferably 10% by weight or more, and preferably 100% by weight or less, more preferably 95% by weight or less. When the content of the thermosetting compound (D) is equal to or more than the above lower limit and equal to or less than the above upper limit, the dielectric constant and dielectric tangent of the cured product can be further reduced, and the thermal dimensional stability of the cured product can be further improved.

<Thermosetting compound having an epoxy group (epoxy compound)>
The thermosetting compound (D) may contain a thermosetting compound having an epoxy group (epoxy compound), or may be a thermosetting compound having an epoxy group (epoxy compound). The above epoxy compounds may be used alone or in combination of two or more kinds.

The above epoxy compounds include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, bisphenol E type epoxy compounds, phenol novolac type epoxy compounds, cresol novolac type epoxy compounds, biphenyl type epoxy compounds, biphenyl novolac type epoxy compounds, biphenol type epoxy compounds, naphthalene type epoxy compounds, fluorene type epoxy compounds, phenol aralkyl type epoxy compounds, naphthol aralkyl type epoxy compounds, dicyclopentadiene type epoxy compounds, anthracene type epoxy compounds, epoxy compounds having an adamantane skeleton, epoxy compounds having a tricyclodecane skeleton, naphthylene ether type epoxy compounds, and epoxy compounds having a triazine nucleus in the skeleton.

The epoxy compound may be a glycidyl ether compound. The glycidyl ether compound is a compound having at least one glycidyl ether group.

The epoxy compound preferably contains an epoxy compound having an aromatic ring, more preferably contains an epoxy compound having a naphthalene skeleton or a phenyl skeleton, and even more preferably is an epoxy compound having an aromatic ring. In this case, the dielectric constant and dielectric tangent of the cured product can be further reduced, and the thermal dimensional stability of the cured product can be further improved.

From the viewpoint of further reducing the dielectric constant and dielectric tangent of the cured product and improving the coefficient of linear expansion (CTE) of the cured product, it is preferable that the epoxy compound contains an epoxy compound that is liquid at 25°C, and it is more preferable that the epoxy compound contains an epoxy compound that is liquid at 25°C and an epoxy compound that is solid at 25°C. In particular, when the epoxy compound contains an epoxy compound that is liquid at 25°C, a resin material with high fluidity is easily obtained when forming the insulating layer, and good lamination properties can be achieved. In addition, because good lamination properties can be achieved, the plating peel strength of the cured product can be further increased.

The viscosity of the epoxy compound that is liquid at 25°C is preferably 10,000 mPa·s or less, and more preferably 5,000 mPa·s or less. The viscosity of the epoxy compound that is liquid at 25°C may be 1 mPa·s or more, 10 mPa·s or more, or 100 mPa·s or more.

The viscosity of the epoxy compound can be measured, for example, using a dynamic viscoelasticity measuring device ("VAR-100" manufactured by Rheologica Instruments).

The molecular weight of the epoxy compound is preferably 1000 or less. In this case, a resin material with high fluidity is easily obtained when forming the insulating layer, and good lamination properties can be obtained. In addition, since good lamination properties can be obtained, the plating peel strength of the cured product can be further increased. The molecular weight of the epoxy compound may be 100 or more, or may be 200 or more.

The molecular weight of the epoxy compound means the molecular weight that can be calculated from the structural formula when the epoxy compound is not a polymer and when the structural formula of the epoxy compound can be specified. When the epoxy compound is a polymer, it means the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

The content of the epoxy compound in the resin material (100% by weight, excluding the solvent) is preferably 1% by weight or more, more preferably 3% by weight or more, and preferably 60% by weight or less, more preferably 50% by weight or less. If the content of the epoxy compound is equal to or more than the lower limit and equal to or less than the upper limit, the dielectric constant and dielectric tangent of the cured product can be further reduced, and the thermal dimensional stability of the cured product can be further improved.

<Thermosetting compound having a vinyl group (vinyl compound)>
The thermosetting compound (D) may contain a thermosetting compound (vinyl compound) having a vinyl group, or may be a thermosetting compound (vinyl compound) having a vinyl group. The above vinyl compounds may be used alone or in combination of two or more kinds.

The vinyl compound may be a divinylbenzyl ether compound.

The content of the vinyl compound is preferably 1% by weight or more, more preferably 3% by weight or more, and preferably 60% by weight or less, more preferably 50% by weight or less, out of 100% by weight of the components excluding the solvent in the resin material. When the content of the vinyl compound is equal to or more than the lower limit and equal to or less than the upper limit, the dielectric constant and dielectric tangent of the cured product can be further reduced, and the thermal dimensional stability of the cured product can be further improved.

<Thermosetting compound having a styryl group (styryl compound)>
The thermosetting compound (D) may contain a thermosetting compound having a styryl group (a styryl compound), or may be a thermosetting compound having a styryl group (a styryl compound). The styryl compound may be used alone or in combination of two or more kinds.

Commercially available styryl compounds include "OPE-2St" and "OPE-1200" manufactured by Mitsubishi Gas Chemical Co., Ltd.

The content of the styryl compound in the resin material (100% by weight, excluding the solvent) is preferably 1% by weight or more, more preferably 3% by weight or more, and preferably 60% by weight or less, more preferably 50% by weight or less. When the content of the styryl compound is equal to or more than the lower limit and equal to or less than the upper limit, the dielectric constant and dielectric tangent of the cured product can be further reduced, and the thermal dimensional stability of the cured product can be further improved.

<Thermosetting compound having a benzoxazine group (benzoxazine compound)>
The thermosetting compound (D) may contain a thermosetting compound having a benzoxazine group (benzoxazine compound), or may be a thermosetting compound having a benzoxazine group (benzoxazine compound). The above-mentioned benzoxazine compound may be used alone or in combination of two or more kinds.

The above benzoxazine compounds include P-d type benzoxazine and Fa type benzoxazine.

Commercially available products of the above benzoxazine compounds include "P-d type" manufactured by Shikoku Chemical Industry Co., Ltd.

The content of the benzoxazine compound in the resin material (100% by weight, excluding the solvent) is preferably 1% by weight or more, more preferably 3% by weight or more, and preferably 60% by weight or less, more preferably 50% by weight or less. If the content of the benzoxazine compound is equal to or more than the lower limit and equal to or less than the upper limit, the dielectric constant and dielectric tangent of the cured product can be further reduced, and the thermal dimensional stability of the cured product can be further improved.

<Thermosetting compound having a cyanate group (cyanate compound)>
The thermosetting compound (D) may contain a thermosetting compound having a cyanate group (cyanate compound), or may be a thermosetting compound having a cyanate group (cyanate compound). The above cyanate compounds may be used alone or in combination of two or more.

The above cyanate compound is preferably a cyanate ester compound.

The above cyanate ester compounds include novolac-type cyanate ester resins, bisphenol-type cyanate ester resins, and prepolymers in which these are partially trimerized. The above novolac-type cyanate ester resins include phenol novolac-type cyanate ester resins and alkylphenol-type cyanate ester resins. The above bisphenol-type cyanate ester resins include bisphenol A-type cyanate ester resins, bisphenol E-type cyanate ester resins, and tetramethylbisphenol F-type cyanate ester resins.

Commercially available products of the above cyanate ester compounds include bisphenol A cyanate ester resin ("P-201" manufactured by Mitsubishi Gas Chemical Co., Ltd.), phenol novolac cyanate ester resin ("PT-30" and "PT-60" manufactured by Lonza Japan), and prepolymers in which bisphenol cyanate ester resins have been trimerized ("BA-230S", "BA-3000S", "BTP-1000S" and "BTP-6020S" manufactured by Lonza Japan).

The content of the cyanate compound in 100% by weight of the components excluding the solvent in the resin material is preferably 1% by weight or more, more preferably 3% by weight or more, and preferably 60% by weight or less, more preferably 50% by weight or less. When the content of the cyanate compound is equal to or more than the lower limit and equal to or less than the upper limit, the dielectric constant and dielectric tangent of the cured product can be further reduced, and the thermal dimensional stability of the cured product can be further improved.

<Thermosetting compound having a methacryloyl group (methacrylic compound)>
The thermosetting compound (D) may contain a thermosetting compound having a methacryloyl group (methacrylic compound), or may be a thermosetting compound having a methacryloyl group (methacrylic compound). The above-mentioned methacrylic compound may be used alone or in combination of two or more kinds.

Commercially available products of the above methacrylic compound include "SA9000-111" manufactured by SABIC.

The content of the methacrylic compound in the resin material (100% by weight, excluding the solvent) is preferably 1% by weight or more, more preferably 3% by weight or more, and preferably 60% by weight or less, more preferably 50% by weight or less. If the content of the methacrylic compound is equal to or more than the lower limit and equal to or less than the upper limit, the dielectric constant and dielectric tangent of the cured product can be further reduced, and the thermal dimensional stability of the cured product can be further improved.

[Cure Accelerator (E)]
The resin material preferably contains a curing accelerator (E). The use of the curing accelerator (E) further accelerates the curing speed. By quickly curing the resin material, the crosslinked structure in the cured product becomes uniform, and the number of unreacted functional groups is reduced, resulting in a high crosslink density. In addition, the use of the curing accelerator (E) allows the resin material to be cured well even at a relatively low temperature. Only one type of curing accelerator (E) may be used, or two or more types may be used in combination.

Examples of the curing accelerator (E) include anionic curing accelerators such as imidazole compounds; cationic curing accelerators such as amine compounds; curing accelerators other than anionic and cationic curing accelerators such as organophosphorus compounds and organometallic compounds; and radical curing accelerators such as peroxides and azo compounds.

The above imidazole compounds include 2-undecylimidazole, 2-heptadecylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1,2-dimethylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, and 1-cyanoethyl-2-phenylimidazolium trimethylate. Limellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-dihydroxymethylimidazole.

The above amine compounds include diethylamine, triethylamine, diethylenetetramine, triethylenetetramine, diethylenetriamine, ethylenediamine, tris(dimethylaminomethyl)phenol, benzyldimethylamine, m-xylylenedi(dimethylamine), N,N'-dimethylpiperazine, N-methylpyrrolidine, N-methylhydroxypiperidine, m-xylylenediamine, isophoronediamine, N-aminoethylpiperazine, polyoxypropylenepolyamine, and 4,4-dimethylaminopyridine. The amine compounds may also be modified versions of these amine compounds.

The above-mentioned organic phosphorus compounds include organic phosphine compounds such as triphenylphosphine, tricyclohexylphosphine, tribenzylphosphine, diphenyl(alkylphenyl)phosphine, tris(alkylphenyl)phosphine, tris(alkoxyphenyl)phosphine, tris(alkylalkoxyphenyl)phosphine, tris(dialkylphenyl)phosphine, tris(trialkylphenyl)phosphine, tris(tetraalkylphenyl)phosphine, tris(dialkoxyphenyl)phosphine, tris(trialkoxyphenyl)phosphine, tris(tetraalkoxyphenyl)phosphine, trialkylphosphine, dialkylarylphosphine, and alkyldiarylphosphine, as well as phosphonium salt compounds such as tetraphenylphosphonium and tetraphenylborate.

The above-mentioned organometallic compounds include zinc naphthenate, cobalt naphthenate, tin octoate, cobalt octoate, cobalt bisacetylacetonate (II), and cobalt trisacetylacetonate (III).

The above peroxides include diacyl peroxides, peroxy esters, peroxy dicarbonates, monoperoxy carbonates, peroxy ketals, dialkyl peroxides, dibenzyl peroxide, dicumyl peroxide, hydroperoxides, and ketone peroxides.

The curing accelerator (E) preferably contains an amine compound, an imidazole compound, a peroxide, an azo compound, or an organic phosphorus compound, and more preferably contains an imidazole compound or a peroxide. In this case, the effect of the present invention can be exerted even more effectively.

In the above resin material, the content of the curing accelerator (E) relative to 100 parts by weight of the total of the maleimide compound (A) and the thermosetting compound (D) is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, preferably 10 parts by weight or less, more preferably 5 parts by weight or less. When the content of the curing accelerator (E) is equal to or more than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited.

[Curing agent (F)]
The resin material preferably contains a curing agent (F). The curing agent (F) is not particularly limited. As the curing agent (F), a conventionally known curing agent can be used. The curing agent (F) may be used alone or in combination of two or more kinds.

Examples of the curing agent (F) include a compound having an active ester group (active ester compound), a compound having a hydroxyl group, a compound having a thiol group, and a compound having an amino group. It is preferable that the curing agent (F) contains an active ester compound.

The content of the curing agent (F) in the resin material is appropriately selected depending on, for example, the content of the maleimide compound (A) and the content of the thermosetting compound (D) in the resin material.

[solvent]
The resin material does not contain or contains a solvent. The resin material may or may not contain a solvent. By using the solvent, the viscosity of the resin material can be controlled within a suitable range, and the coatability of the resin material can be improved. The solvent may be used to obtain a slurry containing hollow inorganic particles (B). Only one type of the solvent may be used, or two or more types may be used in combination.

The above solvents include acetone, methanol, ethanol, butanol, 2-propanol, 2-methoxyethanol, 2-ethoxyethanol, 1-methoxy-2-propanol, 2-acetoxy-1-methoxypropane, toluene, xylene, methyl ethyl ketone, N,N-dimethylformamide, methyl isobutyl ketone, N-methyl-pyrrolidone, n-hexane, cyclohexane, cyclohexanone, and naphtha, which is a mixture.

Most of the solvent is preferably removed when the resin composition is formed into a film. Therefore, the boiling point of the solvent is preferably 200°C or less, more preferably 180°C or less. The boiling point of the solvent may be 30°C or more, 50°C or more, or 100°C or more. There are no particular limitations on the content of the solvent in the resin composition. The content of the solvent can be changed as appropriate, taking into account the coatability of the resin composition, etc.

If the resin material is a B-stage film, the content of the solvent in 100% by weight of the B-stage film is preferably 1% by weight or more, more preferably 2% by weight or more, preferably 15% by weight or less, more preferably 10% by weight or less.

[Other ingredients]
For the purpose of improving impact resistance, heat resistance, resin compatibility, workability, etc., the resin material may contain other components in addition to the above-mentioned components (maleimide compound (A), hollow inorganic particles (B), solid inorganic particles (C), thermosetting compound (D), curing accelerator (E), curing agent (F) and solvent). Examples of the other components include thermoplastic resins; organic fillers; leveling agents; flame retardants; coupling agents; colorants; antioxidants; ultraviolet degradation inhibitors; defoamers; thickeners; thixotropy-imparting agents, etc. The other components may be used alone or in combination of two or more.

The above-mentioned thermoplastic resins include polyimide resins, phenoxy resins, and polyvinyl acetal resins.

The above-mentioned coupling agents include silane coupling agents, titanium coupling agents, and aluminum coupling agents. The above-mentioned silane coupling agents include vinyl silane, amino silane, imidazole silane, and epoxy silane.

The resin material may or may not contain glass cloth. It is preferable that the resin material does not contain glass cloth. It is preferable that the resin material is not a prepreg.

(Resin film)
The resin composition described above is molded into a film to obtain a resin film (B-stage product/B-stage film). The resin material is preferably a resin film. The resin film is preferably a B-stage film.

　Methods for forming a resin composition into a film to obtain a resin film include the following: Extrusion molding, in which the resin composition is melt-kneaded and extruded using an extruder, and then molded into a film using a T-die or circular die. Casting molding, in which a resin composition containing a solvent is cast into a film. Other conventionally known film molding methods. Extrusion molding and casting molding are preferred because they can be made thinner. Films include sheets.

The resin composition is molded into a film and dried by heating for 1 to 10 minutes at, for example, 50°C to 150°C, to the extent that the heat does not cause excessive curing, to obtain a resin film that is a B-stage film.

The film-like resin composition that can be obtained by the drying process described above is called a B-stage film. The B-stage film is in a semi-cured state. A semi-cured product is not completely cured, and curing can continue.

The resin film does not have to be a prepreg. If the resin film is not a prepreg, migration will not occur along the glass cloth or the like. In addition, when the resin film is laminated or precured, irregularities caused by the glass cloth will not occur on the surface.

The resin film can be used in the form of a laminated film comprising a metal foil or a base film and a resin film laminated on the surface of the metal foil or base film. The metal foil is preferably a copper foil.

The base film of the laminated film may be a polyester resin film such as a polyethylene terephthalate film or a polybutylene terephthalate film, an olefin resin film such as a polyethylene film or a polypropylene film, or a polyimide resin film. The surface of the base film may be subjected to a release treatment, if necessary.

From the viewpoint of controlling the degree of hardening of the resin film more uniformly, the thickness of the resin film is preferably 5 μm or more and preferably 200 μm or less. When the resin film is used as an insulating layer of a circuit, the thickness of the insulating layer formed by the resin film is preferably equal to or greater than the thickness of the conductor layer (metal layer) that forms the circuit. The thickness of the insulating layer is preferably 5 μm or more and preferably 200 μm or less.

(Other details of resin material)
When the resin material is heated at 180° C. for 30 minutes and then heated at 200° C. for 60 minutes to obtain a cured product of the resin material, the dielectric constant (Dk) of the obtained cured product at 10 GHz is preferably 2.5 or less, more preferably less than 2.5, even more preferably 2.2 or less, even more preferably 2.0 or less, and particularly preferably less than 2.0. The dielectric constant (Dk) of the obtained cured product at 10 GHz may be 0 or more, or may exceed 0.

The dielectric constant (Dk) of the cured product at 10 GHz can be measured as follows. The resin material is heated at 180°C for 30 minutes, and then heated at 200°C for 60 minutes to obtain a cured product of the resin material. The dielectric constant (Dk) of the resulting cured product is measured by the cavity resonance method using a dielectric constant measuring device (for example, the "Cavity Resonance Perturbation Method Dielectric Constant Measuring Device CP521" manufactured by Kanto Electronics Application Development Co., Ltd.) at room temperature (23°C) and a frequency of 10 GHz.

When using the above resin material to manufacture electronic components such as multilayer boards, the resin material may be heated at 180°C for 30 minutes and then at 200°C for 60 minutes to obtain a cured product, or the resin material may be heated under heating conditions other than these to obtain a cured product.

The above resin material can be used for various applications. For example, the above resin material is suitable for use in forming a molded resin for embedding a semiconductor chip in a semiconductor device. The above resin material is also suitable for use as an alternative to liquid crystal polymer (LCP), for millimeter wave antenna applications, and for rewiring layer applications. The above resin material is not limited to the above applications, and is suitable for use in general wiring formation applications.

The above resin material is preferably used as an adhesive material. The above resin material is preferably used as, for example, an adhesive material for power overlay packages, an adhesive material for printed wiring boards, an adhesive material for coverlays of flexible printed circuit boards, and an adhesive material for semiconductor bonding. The above resin material is preferably an adhesive material.

The above resin material is preferably used as an insulating material. The above resin material is preferably used to form an insulating layer in a printed wiring board, and more preferably used to form an insulating layer in a multilayer printed wiring board. The above resin material is preferably an insulating material, and more preferably an interlayer insulating material. The above insulating material may also function as an adhesive material.

The cured product according to the present invention is a cured product of a resin material obtained by curing the resin material described above. The cured product according to the present invention is a cured product of a resin material, and the resin material is the resin material described above. The cured product according to the present invention can be obtained by curing the resin material described above. The heating conditions for the resin material when obtaining the cured product according to the present invention are not particularly limited, as long as the resin material is cured.

(Laminated structure and copper-clad laminate)
A laminated structure can be obtained by laminating a laminated target member having a metal layer on one or both sides of the resin film. The laminated structure includes a laminated target member having a metal layer on its surface and a resin film laminated on the surface of the metal layer, and the resin film is the above-mentioned resin material. The method of laminating the resin film and the laminated target member is not particularly limited, and a known method can be used. For example, the resin film can be laminated on the laminated target member while applying pressure with or without heating using a device such as a parallel plate press or a roll laminator.

The material of the metal layer is preferably copper.

The laminated member having the metal layer on its surface may be a metal foil such as copper foil.

The above resin material is preferably used to obtain a copper-clad laminate. One example of the above copper-clad laminate is a copper-clad laminate that includes copper foil and a resin film laminated on one surface of the copper foil, the resin film being made of the above resin material.

The thickness of the copper foil of the copper-clad laminate is not particularly limited. The thickness of the copper foil is preferably 1 μm or more and 100 μm or less. In addition, in order to increase the adhesive strength between the cured resin material and the copper foil, it is preferable that the copper foil has fine irregularities on its surface. The method of forming the irregularities is not particularly limited. Examples of the method of forming the irregularities include a method of forming the irregularities by treatment using a known chemical solution, a method of forming the irregularities by known plasma treatment, and a method of forming the irregularities by known UV treatment.

(Circuit board with insulating layer)
The resin material is preferably used to obtain a circuit board with an insulating layer. One example of the circuit board with an insulating layer is a circuit board with an insulating layer that includes a circuit board and an insulating layer disposed on a surface of the circuit board, the insulating layer being a cured product of the resin material described above.

In the circuit board with an insulating layer, it is preferable that the insulating layer is laminated on the surface of the circuit board on which the circuits are provided. In the circuit board with an insulating layer, it is preferable that a portion of the insulating layer is embedded between the circuits.

The above-mentioned circuit board with insulating layer can be obtained by a conventional method.

(Multilayer boards and multilayer printed wiring boards)
The resin material is preferably used to obtain a multilayer board. An example of the multilayer board is a multilayer board including a circuit board and an insulating layer laminated on the circuit board. The insulating layer of the multilayer board is a cured product of the resin material. The insulating layer is preferably laminated on the surface of the circuit board on which the circuit (metal layer) is provided. A part of the insulating layer is preferably embedded between the circuits.

In the multilayer board, it is preferable that the surface of the insulating layer opposite the surface on which the circuit board is laminated is roughened.

The roughening method can be a conventionally known roughening method, and is not particularly limited. The surface of the insulating layer may be subjected to a swelling treatment before the roughening treatment. After the roughening treatment, it is preferable to perform ultrasonic treatment in order to remove the hollow inorganic particles (B) (and the solid inorganic particles (C)) from the surface of the insulating layer.

It is also preferable that the multilayer substrate further comprises a copper plating layer laminated on the roughened surface of the insulating layer.

Another example of the multilayer board is a multilayer board comprising a circuit board, an insulating layer laminated on the surface of the circuit board, and copper foil laminated on the surface of the insulating layer opposite to the surface on which the circuit board is laminated. It is preferable that the insulating layer is formed by using a copper-clad laminate comprising copper foil and a resin film laminated on one surface of the copper foil, and curing the resin film. Furthermore, it is preferable that the copper foil is etched to form a copper circuit.

Another example of the multilayer board is a multilayer board comprising a circuit board and a plurality of insulating layers laminated on a surface of the circuit board. At least one of the plurality of insulating layers arranged on the circuit board is formed using the resin material. It is preferable that the multilayer board further comprises a circuit laminated on at least one surface of the insulating layer formed using the resin film.

The above resin materials are suitable for use in forming insulating layers in multilayer printed wiring boards.

The multilayer printed wiring board includes, for example, a circuit board, a plurality of insulating layers arranged on the surface of the circuit board, and a metal layer arranged between the insulating layers. In the multilayer printed wiring board, at least one of the insulating layers is a cured product of the resin material described above.

FIG. 1 is a cross-sectional view showing a multilayer printed wiring board using a resin material according to one embodiment of the present invention.

In the multilayer printed wiring board 11 shown in FIG. 1, a plurality of insulating layers 13-16 are laminated on the upper surface 12a of the circuit board 12. The insulating layers 13-16 are hardened layers. A metal layer 17 is formed on a partial area of the upper surface 12a of the circuit board 12. Of the plurality of insulating layers 13-16, the insulating layers 13-15 other than the insulating layer 16 located on the outer surface opposite the circuit board 12 side have a metal layer 17 formed on a partial area of the upper surface. The metal layer 17 is a circuit. The metal layer 17 is disposed between the circuit board 12 and the insulating layer 13, and between each of the laminated insulating layers 13-16. The lower metal layer 17 and the upper metal layer 17 are connected to each other by at least one of a via hole connection and a through hole connection, not shown.

In the multilayer printed wiring board 11, the insulating layers 13 to 16 are formed from a cured product of the above-mentioned resin material. In this embodiment, the surfaces of the insulating layers 13 to 16 are roughened, so that fine holes (not shown) are formed in the surfaces of the insulating layers 13 to 16. The metal layer 17 extends into the fine holes. In the multilayer printed wiring board 11, the width dimension (L) of the metal layer 17 and the width dimension (S) of the portion where the metal layer 17 is not formed can be reduced. In the multilayer printed wiring board 11, good insulation reliability is provided between the upper metal layer and the lower metal layer that are not connected by via hole connections and through hole connections (not shown).

The present invention will be specifically explained below by giving examples and comparative examples. The present invention is not limited to the following examples.

The following materials were prepared:

(Maleimide Compound (A))
Maleimide compound A1 ("BMI1500" manufactured by Designer Molecules Inc., a maleimide compound having an aromatic skeleton and a linear aliphatic skeleton, number of maleimide groups: 2, weight average molecular weight: 1500)
Maleimide compound A2 (synthesized according to Synthesis Example A2 below, number of maleimide groups: 2, weight average molecular weight: 4300)
Maleimide compound A3 (synthesized according to Synthesis Example A3 below, number of maleimide groups: 2, weight average molecular weight: 12,000)

<Synthesis Example A2>
In a 500 mL eggplant flask, 105 g of toluene, 41 g of N-methyl-2-pyrrolidone (NMP), and 7 g of methanesulfonic acid were placed. Then, 9.9 g (24.2 mmol) of dimer diamine ("PRIAMINE 1075" manufactured by Croda Japan) and 8.6 g (55.8 mmol) of norbornane diamine ("Pro-NBDA" manufactured by Mitsui Fine Chemicals) were added. Then, 15.9 g (54 mmol) of biphenyl dianhydride and 1.5 g (6 mmol) of bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride were mixed and then added little by little. The eggplant flask was attached to a Dean-Stark apparatus and heated under reflux for 3.5 hours. In this way, a compound having amines at both ends and having multiple imide skeletons was obtained. The water discharged during the condensation was removed, and the mixture was returned to room temperature, after which 4.42 g (45 mmol) of maleic anhydride was added, stirred, and similarly heated to react. In this way, a compound having a maleimide skeleton at both ends was obtained. The organic layer was washed with a mixed solvent of water and ethanol, and the mixed solvent was removed to obtain a toluene solution. Next, isopropanol was added to the toluene solution to reprecipitate the product. The mixture was then dried in a vacuum oven to obtain maleimide compound A2.

<Synthesis Example A3>
In a 500 mL eggplant flask, 105 g of toluene, 41 g of N-methyl-2-pyrrolidone (NMP), and 7 g of methanesulfonic acid were placed. Then, 9.3 g (23 mmol) of dimer diamine ("PRIAMINE 1075" manufactured by Croda Japan) and 10.2 g (53 mmol) of tricyclodecane diamine were added. Then, 13.1 g (60 mmol) of pyromellitic dianhydride was added little by little. The eggplant flask was attached to a Dean-Stark apparatus and heated under reflux for 3.5 hours. In this way, a compound having amines at both ends and multiple imide skeletons was obtained. After removing the moisture discharged during condensation and returning to room temperature, 4.42 g (45 mmol) of maleic anhydride was added and stirred, and similarly heated and reacted. In this way, a compound having maleimide skeletons at both ends was obtained. The organic layer was washed with a mixed solvent of water and ethanol, and the mixed solvent was removed to obtain a toluene solution. Next, isopropanol was added to the toluene solution to reprecipitate the product, which was then dried in a vacuum oven to obtain maleimide compound A3.

(Thermosetting compound (D))
Divinylbenzene (viscosity at 25°C: 1 mPa·s)
Polyphenylene ether-methacrylic acid compound (SABIC SA9000-111, solid at 25°C)
Oligophenylene ether-styrene compound ("OPE-2St" manufactured by Mitsubishi Gas Chemical Co., Ltd.)
Biphenyl-type epoxy compound ("NC-3000" manufactured by Nippon Kayaku Co., Ltd., solid at 25°C)

(Hollow inorganic particles (B))
Hollow silica particles B1 (AGC "HS-070", BET specific surface area (S): 18.5 m ² /g, average particle radius (r): 0.3 μm, true density (d): 0.58 g/cm ³ , Porosity: 70% by volume
Hollow silica particles B2 (“HS-200” manufactured by AGC, BET specific surface area (S): 12.8 m ² /g, average particle radius (r): 1 μm, true density (d): 0.45 g/cm ³ , Porosity: 75% by volume)

(Hollow inorganic particles not corresponding to hollow inorganic particles (B))
Hollow silica particles X ("L6SZ-AC1" manufactured by Admatechs Co., Ltd., BET specific surface area (S): 12.4 m ² /g, average particle radius (r): 0.3 μm, true density (d): 0.8 g/cm ³ , porosity: 40% by volume)
Hollow aluminosilicate particles ("CellSpheres-NF (small particle size)" manufactured by Taiheiyo Cement Corporation), BET specific surface area (S): 4.0 m ² /g, average particle radius (r): 0.5 μm, true density (d): 0.55 g/cm ³ , porosity: 75% by volume

The BET specific surface area (S), average particle radius (r), true density (d) and porosity of the hollow inorganic particles were measured according to the method described above. The device used to measure the BET specific surface area (S) was the "NOVA4200e" manufactured by Quantachrome Instruments, and the device used to measure the true density (d) was the "Ultrapyc1200e" manufactured by Quantachrome.

The composition of the hollow inorganic particles is shown in Table 1 below.

(Solid Inorganic Particles (C))
Solid silica particles ("SC2050-HNG" manufactured by Admatechs Co., Ltd., average particle radius: 0.25 μm)

(Cure Accelerator (E))
Peroxide (NOF Corp. "Perbutyl P")
Imidazole compound (2-phenyl-4-methylimidazole, "2P4MZ" manufactured by Shikoku Chemical Industry Co., Ltd., anionic curing accelerator)

(Curing agent (F))
Active ester compound-containing liquid (DIC Corporation "HPC-8000L-65T", solid content 65% by weight)

(Examples 1 to 11 and Comparative Examples 1 to 4)
The components shown in Tables 2 to 5 below were mixed in the amounts (unit: parts by weight of solid content) shown in Tables 2 to 5 below, and stirred at room temperature until a homogeneous solution was obtained, to obtain a resin material.

Preparation of resin film:
The obtained resin material was applied to the release-treated surface of a release-treated polyethylene terephthalate film (PET film, Toray Industries, Inc., "XG284", thickness 25 μm) using an applicator, and then dried for 2 minutes and 30 seconds in a gear oven at 100° C. to volatilize the solvent. In this way, a laminated film (a laminated film of a PET film and a resin film) was obtained in which a resin film (B-stage film) having a thickness of 40 μm was laminated on the PET film.

(evaluation)
(1) Dielectric constant (Dk) and dielectric loss tangent (Df) of the cured product
The obtained resin film (B-stage film) having a thickness of 40 μm was heated at 180° C. for 30 minutes, and then heated at 200° C. for 60 minutes to obtain a cured product. The obtained cured product was cut into a size of 2 mm wide and 80 mm long, and 10 sheets were stacked together to obtain a measurement sample. The dielectric constant (Dk) and dielectric loss tangent (Df) of the cured product were measured at room temperature (23° C.) and a frequency of 10 GHz by the cavity resonance method using a "Cavity Resonance Perturbation Method Dielectric Constant Measurement Device CP521" manufactured by Kanto Electronics Application Development Co., Ltd. and a "Network Analyzer N5224A PNA" manufactured by Keysight Technologies, Inc.

[Criteria for dielectric constant (Dk) of cured product]
○: Dielectric constant is less than 2.0 △: Dielectric constant is 2.0 or more and 2.5 or less ×: Dielectric constant is more than 2.5

[Criteria for dielectric tangent (Df) of cured product]
◯: Dielectric loss tangent is less than 0.003 △: Dielectric loss tangent is 0.003 or more and less than 0.005 ×: Dielectric loss tangent is 0.005 or more

(2) Glass transition temperature (Tg) of the cured product
The obtained resin film having a thickness of 40 μm was heated at 180° C. for 30 minutes to be temporarily cured, and then heated at 200° C. for 60 minutes to obtain a cured product. The obtained cured product was cut into a size of 5 mm×50 mm. Using a thermomechanical analyzer (SII Nanotechnology Inc.'s "DMS6100"), measurements were performed under the following conditions: chuck distance 20 mm, amplitude 10 μm, initial tension amplitude value 400 mN, temperature increase rate of 5° C./min from 50° C. to 330° C., and frequency of 10 Hz. In the obtained measurement results, the peak temperature of the loss tangent was taken as the glass transition temperature Tg (° C.).

[Criteria for determining glass transition temperature (Tg) of cured product]
◯: Glass transition temperature is 120° C. or higher △: Glass transition temperature is 100° C. or higher and less than 120° C. ×: Glass transition temperature is less than 100° C.

(3) Lamination A 100 mm square substrate having a rectangular recess of 1 mm x 2 mm was prepared by etching the copper with a mask attached so that a rectangular range of 1 mm x 2 mm was etched on a copper layer having a thickness of 18 μm. Both sides of the copper foil surface of this substrate were immersed in "Cz8101" manufactured by Mec Co., Ltd. to roughen the surface of the copper foil. Using "Batch-type vacuum laminator MVLP-500-IIA" manufactured by Meiki Seisakusho Co., Ltd., the resin film (B stage film) side of the laminated film was laminated on both sides of the roughened substrate to obtain a laminated structure. The lamination conditions were as follows: decompression for 30 seconds to make the air pressure 13 hPa or less, then lamination at 100 ° C. and pressure 0.7 MPa for 30 seconds, and further pressing for 60 seconds at a press pressure of 0.8 MPa and a press temperature of 100 ° C. The PET film was peeled off, and the resin film was semi-cured by heating at 100° C. for 30 minutes and then further heating at 180° C. for 30 minutes. The surface of the semi-cured resin film in the portion where the copper pattern was present (the surface opposite the substrate) and the surface of the semi-cured resin film in the portion where the copper pattern was not present (the surface opposite the substrate) were observed, and the maximum height difference between adjacent concave and convex portions was determined using an optical step gauge.

[Lamination criteria]
○: The maximum height difference is less than 1.5 μm △: The maximum height difference is 1.5 μm or more and less than 2 μm ×: The maximum height difference is 2 μm or more

(4) Cracks in particles (hollow inorganic particles or solid inorganic particles) after lamination After the evaluation of "(3) Lamination property" above, the semi-cured resin film was cut into pieces of 2 cm x 1 cm in size. The cut pieces were embedded in resin, and then the resin and the cut pieces were polished to expose the cross section of the cut piece (cross section along the thickness direction of the semi-cured resin film). The exposed cross section was observed at a magnification of 5000 times using a scanning electron microscope (SEM, "JSM-561 0LV" manufactured by JEOL Datum Co., Ltd.). It was confirmed whether or not cracks occurred in 30 randomly selected particles.

[Criteria for determining particle cracking after lamination]
◯: out of 30 particles, the number of particles with cracks is 3 or less. ×: out of 30 particles, the number of particles with cracks is 4 or more.

(5) Cracks of Particles (Hollow Inorganic Particles or Solid Inorganic Particles) After Ultrasonic Treatment After the evaluation of "(3) Lamination property" above, the following "(5-1) Roughening Treatment" and "(5-2) Observation with a Scanning Electron Microscope" were performed.

(5-1) Roughening treatment:
(a) Swelling treatment:
The laminate of the substrate and the semi-cured resin film obtained in the above "(3) Lamination property" was placed in a swelling liquid ("Swelling Dip Securigant P" manufactured by Atotech Japan) at 60°C and swung for 10 minutes. Thereafter, it was washed with pure water.

(b) Permanganate treatment (roughening treatment and desmear treatment):
The laminate after the swelling treatment was placed in a roughening aqueous solution of potassium permanganate ("Concentrate Compact CP" manufactured by Atotech Japan) at 80° C. and swung for 30 minutes. Next, it was treated for 2 minutes using a cleaning solution ("Reduction Securigant P" manufactured by Atotech Japan) at 25° C., and then washed in pure water by applying ultrasonic vibrations at a frequency of 40 kHz for 200 seconds.

(5-2) Observation by scanning electron microscope:
The cured product after ultrasonic treatment (roughened cured product) was cut into pieces of 2 cm x 1 cm. The cut products were embedded in resin, and then the resin and the cut products were polished to expose the cross section of the cut product (cross section along the thickness direction of the cured product). The exposed cross section was observed at a magnification of 5000 times using a scanning electron microscope (SEM, JSM-561 0LV manufactured by JEOL Datum Co., Ltd.). Thirty randomly selected particles were checked for the presence or absence of cracks.

[Criteria for determining particle cracking after ultrasonic treatment]
◯: out of 30 particles, the number of particles with cracks is 3 or less. ×: out of 30 particles, the number of particles with cracks is 4 or more.

(6) Amount of plating penetration After the above "(5-1) Roughening treatment", the below-mentioned "(6-1) Electroless plating treatment" was carried out to obtain a cured product having a copper plating layer laminated on its upper surface. The obtained cured product having a copper plating layer laminated on its upper surface was used to carry out the below-mentioned "(6-2) Measurement of the amount of plating penetration".

(6-1) Electroless plating treatment:
The roughened surface of the cured product was treated with an alkaline cleaner at 60° C. (Atotech Japan's "Cleaner Securigant 902") for 5 minutes, and degreased and washed. After washing, the cured product was treated with a pre-dip liquid at 25° C. (Atotech Japan's "Pre-dip Neogant B") for 2 minutes. Thereafter, the cured product was treated with an activator liquid at 40° C. (Atotech Japan's "Activator Neogant 834") for 5 minutes to attach a palladium catalyst. Next, the cured product was treated with a reducing liquid at 30° C. (Atotech Japan's "Reducer Neogant WA") for 5 minutes. Next, the cured product was placed in a chemical copper liquid (Atotech Japan's "Basic Printgant MSK-DK", "Copper Printgant MSK", "Stabilizer Printgant MSK", and "Reducer Cu"), and electroless plating was performed until the plating thickness reached about 0.5 μm. After the electroless plating, the plate was annealed for 30 minutes at 120° C. to remove residual hydrogen gas. All steps up to the electroless plating step were carried out using 2 L of treatment solution in a beaker scale while the cured product was being rocked. In this way, a cured product was obtained with a copper plating layer laminated on the upper surface.

(6-2) Measurement of plating penetration:
The interface between the copper plating layer and the cured product in the cured product with the copper plating layer laminated on the upper surface was observed at a magnification of 5000 times using an FE-SEM. In addition, during the observation, the cured product with the copper plating layer laminated on the upper surface was arranged so that the copper plating layer was on the upper side and the cured product was on the lower side, and the interface between the copper plating layer and the cured product was horizontal. As shown in FIG. 2, in a region of 20 μm in width of the obtained microscope image, a line that contacts the cured product at the top of the microscope image and is parallel to the interface between the copper plating layer and the cured product was designated as line L1. Also, as shown in FIG. 2, in a region of 20 μm in width of the obtained microscope image, a line that contacts the copper plating at the bottom of the microscope image and is parallel to the interface between the copper plating layer and the cured product was designated as line L2. Also, as shown in FIG. 2, the distance between line L1 and line L2 was designated as the plating penetration amount D. In addition, the smaller the plating penetration amount D, the more the short circuit between the wirings can be suppressed.

[Criteria for determining the amount of plating penetration]
○: The plating penetration amount D is less than 3 μm. ×: The plating penetration amount D is 3 μm or more.

The compositions and results are shown in Tables 2 to 5 below.

11: multilayer printed wiring board 12: circuit board 12a: upper surface 13-16: insulating layers 17: metal layer

Claims (14)

A composition comprising a maleimide compound (A) and hollow inorganic particles (B),
The resin material, wherein the BET specific surface area of the hollow inorganic particles (B) satisfies the following formula (1):
1.05×(3/rd)<S<2.00×(3/rd)...(1)
S: BET specific surface area (m ² /g) of hollow inorganic particles (B)
r: average particle radius of hollow inorganic particles (B) (μm)
d: true density of hollow inorganic particles (B) (g/cm ³ ) The resin material according to claim 1, wherein the content of the maleimide compound (A) is 20% by weight or more and 70% by weight or less out of 100% by weight of the components excluding the solvent in the resin material. The resin material according to claim 1 or 2, wherein the maleimide compound (A) has a skeleton derived from dimer diamine. The resin material according to any one of claims 1 to 3, wherein the maleimide compound (A) has a skeleton derived from a dimer diamine and a skeleton derived from a diamine compound having an alicyclic skeleton other than a dimer diamine. The resin material according to claim 4, wherein the diamine compound having an alicyclic skeleton other than the dimer diamine is tricyclodecane diamine, norbornane diamine, or isophorone diamine. The resin material according to any one of claims 1 to 5, wherein the content of the hollow inorganic particles (B) is 60% by weight or less out of 100% by weight of the components excluding the solvent in the resin material. The resin material according to any one of claims 1 to 6, further comprising solid inorganic particles (C). The resin material according to any one of claims 1 to 7, further comprising a thermosetting compound (D) having a functional group capable of reacting with a maleimide group. The resin material according to claim 8, wherein the thermosetting compound (D) includes a thermosetting compound having an epoxy group, a vinyl group, a styryl group, a benzoxazine group, a cyanate group, an allyl group, a methacryloyl group, or an acryloyl group. The resin material according to any one of claims 1 to 9, in which when the resin material is heated at 180°C for 30 minutes and then heated at 200°C for 60 minutes to obtain a cured product of the resin material, the resulting cured product has a dielectric constant of 2.5 or less at 10 GHz. The resin material according to any one of claims 1 to 10, which is a resin film. The resin material according to any one of claims 1 to 11, which is used to form an insulating layer in a multilayer printed wiring board. A cured product of a resin material,
A cured product, wherein the resin material is the resin material according to any one of claims 1 to 12. A circuit board;
a plurality of insulating layers disposed on a surface of the circuit board;
a metal layer disposed between a plurality of the insulating layers;
A multilayer printed wiring board, wherein at least one of the insulating layers is a cured product of the resin material according to any one of claims 1 to 12.

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