JP7565982B2 - Resin materials and multilayer printed wiring boards - Google Patents

Description

The present invention relates to a resin material containing an epoxy compound. The present invention also relates to a multilayer printed wiring board using the above resin material.

Conventionally, 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. In addition, resin films in which the resin materials are filmized may be used to form the insulating layers. The resin materials and resin films are used as insulating materials for multilayer printed wiring boards, including build-up films.

As an example of the above resin material, the following Patent Document 1 discloses a thermosetting resin composition containing an active ester resin having a resin structure with specific structural moieties and both ends of which are monovalent aryloxy groups, and an epoxy resin. In the examples of Patent Document 1, the above thermosetting resin composition is impregnated into glass cloth.

In addition, the following Patent Document 2 discloses a resin composition containing an active ester resin having a specific structure and an epoxy resin. In the examples of Patent Document 2, glass cloth is impregnated with the above resin composition.

WO2016/098488A1 JP 2018-080264 A

Conventional resin materials may have poor storage stability. For example, the melt viscosity of the resin material after storage may increase compared to the resin material before storage. Furthermore, conventional resin materials may have poor embedding properties (pattern embedding properties) in uneven surfaces of a substrate, etc., and may be difficult to form fine wiring when used after storage compared to the resin material before storage.

In order to lower the dielectric tangent of the insulating layer (cured product), a large amount of inorganic filler may be blended into the resin material. However, resin materials that contain a large amount of inorganic filler tend to have a reduced storage stability. In the examples of Patent Document 1, no inorganic filler is used. In the examples of Patent Document 2, only 50% by weight of inorganic filler is used relative to 100% by weight of the resin material. Even with the resin materials described in Patent Documents 1 and 2, if the amount of inorganic filler is increased, the storage stability of the resin material may be reduced.

In addition, when an insulating layer (cured product) is formed using conventional resin materials, cracks or breaks may occur in the insulating layer due to thermal shock. If cracks or breaks occur in the insulating layer, the electrical conductivity reliability decreases.

The object of the present invention is to provide a resin material that has excellent storage stability and is less likely to crack or break when cured even when subjected to thermal shock. Another object of the present invention is to provide a multilayer printed wiring board using the above resin material.

According to a broad aspect of the present invention, there is provided a resin material (excluding resin materials used by impregnating a fiber substrate) that includes an epoxy compound, an inorganic filler, and a curing agent, the curing agent including an active ester compound having a structure represented by the following formula (1), and the content of the inorganic filler is 55% by weight or more out of 100% by weight of the components in the resin material excluding the solvent.

In the formula (1), R1, R2, and X1 each represent an organic group, X2 represents a group containing an aliphatic chain skeleton, a group containing an aliphatic skeleton, or a group containing an aromatic skeleton, m represents an integer of 1 to 6, and n represents an integer of 1 to 5.

In a particular aspect of the resin material according to the present invention, in formula (1), X1 is an organic group having 5 or more carbon atoms.

In a particular aspect of the resin material according to the present invention, in formula (1), X1 is a group having an aromatic skeleton.

In a particular aspect of the resin material according to the present invention, in formula (1), X1 is a group having two or more aromatic skeletons.

In a particular aspect of the resin material according to the present invention, in formula (1), X1 is a group that does not have a reactive group.

In a particular aspect of the resin material according to the present invention, in formula (1), R1 or R2 is a group having a heteroaromatic ring skeleton.

In a particular aspect of the resin material according to the present invention, in formula (1), R1 or R2 is a group having an imide skeleton.

In a particular aspect of the resin material according to the present invention, in formula (1), R1 or R2 is a group having a naphthalene skeleton.

In a particular aspect of the resin material according to the present invention, in formula (1), R1, R2, X1, and X2 are each a group that does not have a phosphorus atom.

In a particular aspect of the resin material according to the present invention, in formula (1), R1, R2, X1, and X2 are each a group having 2 to 4 carbon atoms and not having an aliphatic hydrocarbon chain.

In a particular aspect of the resin material according to the present invention, the melt viscosity at 100°C is 5 Pa·s or more and 500 Pa·s or less.

In a particular aspect of the resin material according to the present invention, the curing agent contains an active ester compound that does not have a side chain.

In a particular aspect of the resin material according to the present invention, the curing agent includes a carbodiimide compound.

In a particular aspect of the resin material according to the present invention, the active ester equivalent of the active ester compound having the structure represented by formula (1) is 200 eq/g or more and 500 eq/g or less.

In a particular aspect of the resin material according to the present invention, the epoxy compound includes a naphthol aralkyl type epoxy compound.

In a particular aspect of the resin material according to the present invention, the inorganic filler is silica.

In a particular aspect of the resin material according to the present invention, the resin material contains a curing accelerator.

In a particular aspect of the resin material according to the present invention, the resin material contains a bismaleimide compound.

In a particular aspect of the resin material according to the present invention, the resin material includes a thermoplastic resin.

In a particular aspect of the resin material according to the present invention, the resin material is a resin film.

The resin material according to the present invention is suitable for use in forming insulating layers in multilayer printed wiring boards.

According to a broad aspect of the present invention, there is provided 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 above-mentioned resin material.

The resin material according to the present invention contains an epoxy compound, an inorganic filler, and a curing agent, and the curing agent contains an active ester compound having a structure represented by formula (1), and the content of the inorganic filler is 55% by weight or more out of 100% by weight of the components in the resin material excluding the solvent. The resin material according to the present invention has the above-mentioned configuration, and therefore has excellent storage stability and is less likely to crack or break in the cured product even when subjected to thermal shock.

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.

The present invention is described in detail below.

The resin material according to the present invention is a resin material (excluding resin materials used by impregnating a fiber substrate) that includes an epoxy compound, an inorganic filler, and a curing agent, the curing agent including an active ester compound having a structure represented by the following formula (1), and the content of the inorganic filler is 55% by weight or more out of 100% by weight of the components in the resin material excluding the solvent.

In the above formula (1), R1, R2, and X1 each represent an organic group, X2 represents a group containing an aliphatic chain skeleton, a group containing an aliphatic skeleton, or a group containing an aromatic skeleton, m represents an integer of 1 to 6, and n represents an integer of 1 to 5.

The resin material according to the present invention has the above-mentioned configuration, and therefore has excellent storage stability and is less likely to crack or break in the cured product even when subjected to thermal shock.

In addition, the resin material according to the present invention has the above-mentioned configuration, so the dielectric tangent of the cured product can be reduced.

The resin material according to the present invention is different from the resin material used by impregnating a fiber substrate. An impregnated substrate in which a fiber substrate is impregnated with a resin material is, for example, a prepreg. The resin material according to the present invention can be used for applications other than prepregs. Examples of the fiber substrate include inorganic fibers such as glass fibers, and organic fibers such as polyester fibers. Therefore, the resin material according to the present invention is different from the resin material used by impregnating the inorganic fibers and the organic fibers.

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 the resin material according to the present invention has excellent handleability, it is preferable that the resin material is a resin film.

When the resin material is a resin film, the storage stability is more likely to decrease. With the resin material according to the present invention, the storage stability can be improved even when the resin material is a resin film.

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

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

[Epoxy Compound]
The resin material includes an epoxy compound. The epoxy compound refers to an organic compound having at least one epoxy group. As the epoxy compound, a conventionally known epoxy compound can be used. The epoxy compound 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, phenol 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.

From the viewpoint of lowering the dielectric tangent and increasing the thermal dimensional stability and flame retardancy of the cured product, the epoxy compound preferably contains an epoxy compound having an aromatic skeleton, more preferably contains an epoxy compound having a naphthalene skeleton or a phenyl skeleton, and even more preferably contains an epoxy compound having a naphthylene ether skeleton. The naphthylene ether skeleton refers to a skeleton in which an oxygen atom is bonded to a carbon atom constituting a naphthalene ring.

From the viewpoint of further lowering the dielectric tangent and further improving the thermal dimensional stability and flame retardancy of the cured product, it is preferable that the above epoxy compound contains a naphthol aralkyl type epoxy compound (an epoxy compound having a naphthylene ether skeleton).

The naphthol aralkyl type epoxy compound preferably has one or more naphthylene ether skeletons, more preferably has two or more naphthylene ether skeletons, even more preferably has three or more naphthylene ether skeletons, and particularly preferably has four or more naphthylene ether skeletons. When the number of naphthylene ether skeletons is equal to or greater than the lower limit, the dielectric tangent can be further reduced.

From the viewpoint of further lowering the dielectric tangent and improving the coefficient of linear expansion (CTE) of the cured product, it is preferable that the above epoxy compound contains an epoxy compound that is liquid at 25°C and an epoxy compound that is solid at 25°C.

The viscosity of the epoxy compound that is liquid at 25°C is preferably 1000 mPa·s or less, and more preferably 500 mPa·s or less, at 25°C.

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

It is more preferable that the molecular weight of the epoxy compound is 1000 or less. In this case, even if the content of the inorganic filler is 55% by weight or more out of 100% by weight of the components excluding the solvent in the resin material, a resin material with high fluidity can be obtained when forming the insulating layer. Therefore, when the uncured or B-staged resin material is laminated onto a circuit board, the inorganic filler can be uniformly present.

When the epoxy compound is not a polymer and when the structural formula of the epoxy compound can be specified, the molecular weight of the epoxy compound means the molecular weight that can be calculated from the structural formula. When the epoxy compound is a polymer, the molecular weight of the epoxy compound means the weight average molecular weight.

From the viewpoint of further enhancing the thermal dimensional stability of the cured product, the content of the above epoxy compound is preferably 10% by weight or more, more preferably 15% by weight or more, and preferably less than 45% by weight, more preferably 40% by weight or less, based on 100% by weight of the components excluding the solvent in the resin material.

In 100% by weight of the components in the resin material excluding inorganic fillers and solvents, the content of the above epoxy compound is preferably 10% by weight or more, more preferably 15% by weight or more, even more preferably 25% by weight or more, and particularly preferably 30% by weight or more. In 100% by weight of the components in the resin material excluding inorganic fillers and solvents, the content of the above epoxy compound is preferably 60% by weight or less, more preferably 50% by weight or less, even more preferably 45% by weight or less, and particularly preferably 40% by weight or less. When the content of the above epoxy compound is equal to or more than the above lower limit and equal to or less than the above upper limit, the thermal dimensional stability of the cured product can be further improved.

[Inorganic filler]
The resin material includes an inorganic filler. By using the inorganic filler, the dielectric tangent of the cured product can be further reduced. In addition, by using the inorganic filler, the dimensional change of the cured product due to heat can be further reduced. The inorganic filler may be used alone or in combination of two or more kinds.

Examples of the inorganic fillers include silica, talc, clay, mica, hydrotalcite, alumina, magnesium oxide, aluminum hydroxide, aluminum nitride, and boron nitride.

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 inorganic filler is preferably silica or alumina, more preferably silica, and even more preferably fused silica. By using silica, the thermal expansion coefficient of the cured product is further reduced, and the dielectric tangent of the cured product is further reduced. In addition, by using silica, 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. The silica is preferably spherical in shape.

From the viewpoint of promoting resin curing regardless of the curing environment, effectively increasing the glass transition temperature of the cured product, and effectively reducing the coefficient of linear thermal expansion of the cured product, it is preferable that the inorganic filler be spherical silica.

The average particle size of the inorganic filler is preferably 50 nm or more, more preferably 100 nm or more, and even more preferably 500 nm or more, and is 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 inorganic filler is equal to or more 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 inorganic filler. The average particle size can be measured using a laser diffraction scattering particle size distribution measuring device.

The inorganic filler is preferably spherical, and more preferably spherical silica. 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 inorganic filler is spherical, the aspect ratio of the inorganic filler is preferably 2 or less, and more preferably 1.5 or less.

The inorganic filler is 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 inorganic filler, the surface roughness of the roughened cured product is further reduced, and the adhesive strength between the cured product and the metal layer is further increased. In addition, by surface-treating the inorganic filler, 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.

Examples of the coupling agent include silane coupling agents, titanium coupling agents, and aluminum coupling agents. Examples of the silane coupling agent include methacrylsilane, acrylic silane, amino silane, imidazole silane, vinyl silane, and epoxy silane.

The content of the inorganic filler is 55% by weight or more out of 100% by weight of the components in the resin material excluding the solvent.

The content of the inorganic filler is preferably 60% by weight or more, more preferably 65% by weight or more, particularly preferably 68% by weight or more, preferably 90% by weight or less, more preferably 85% by weight or less, even more preferably 80% by weight or less, and particularly preferably 75% by weight or less, out of 100% by weight of the components excluding the solvent in the resin material. When the content of the inorganic filler is equal to or greater than the lower limit, the dielectric tangent is effectively lowered. When the content of the inorganic filler is equal to or less than the upper limit, the storage stability of the resin material can be improved, and the thermal dimensional stability of the cured product can be improved. When the content of the inorganic filler 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 inorganic filler, it is possible to lower the thermal expansion coefficient of the cured product and at the same time improve the smear removal properties.

[Curing agent]
The resin material contains a curing agent. The curing agent may be used alone or in combination of two or more kinds.

<First active ester compound>
The resin material contains an active ester compound having a structure represented by the following formula (1) (hereinafter, may be referred to as a "first active ester compound") as a curing agent. Only one type of the first active ester compound may be used, or two or more types may be used in combination.

In the above formula (1), R1, R2, and X1 each represent an organic group, X2 represents a group containing an aliphatic chain skeleton, a group containing an aliphatic skeleton, or a group containing an aromatic skeleton, m represents an integer of 1 to 6, and n represents an integer of 1 to 5.

In the above formula (1), m is preferably 2 or more and preferably 4 or less.

In the above formula (1), n is preferably 3 or less.

In the above formula (1), X1 may be a group in which the same structural unit is repeated. In the above formula (1), when X1 is a group in which the same structural unit is repeated, the number of repetitions of the structural unit is preferably 1 or more and 6 or less.

In the above formula (1), X1 is preferably an organic group having 5 or more carbon atoms, more preferably an organic group having 7 or more carbon atoms, and even more preferably an organic group having 10 or more carbon atoms. In the above formula (1), X1 is preferably an organic group having 50 or less carbon atoms, more preferably an organic group having 40 or less carbon atoms, and even more preferably an organic group having 30 or less carbon atoms. In this case, cracks or cracks in the cured product when subjected to thermal shock can be effectively suppressed.

In the above formula (1), X1 is preferably a group having an aromatic skeleton. In this case, cracks or fractures in the cured product when subjected to thermal shock can be effectively suppressed.

Examples of the group having an aromatic skeleton include a group having a benzene ring which may have a substituent, and a group having a naphthalene ring which may have a substituent.

In the above formula (1), X1 is preferably a group having two or more aromatic skeletons, and more preferably a group having three or more aromatic skeletons. In this case, cracks or breakage of the cured product when subjected to thermal shock can be more effectively prevented.

In the above formula (1), X1 is preferably a group represented by the following formula (1a). In this case, cracks or breaks in the cured product when subjected to thermal shock can be suppressed even more effectively.

In the above formula (1a), k represents an integer of 1 or more and 6 or less.

In the above formula (1a), k is preferably 2 or more, more preferably 3 or more, and preferably 5 or less.

In the above formula (1), X1 is preferably a group that does not have a reactive group. In this case, the storage stability of the resin material can be improved, and cracks or fractures in the cured product when subjected to thermal shock can be suppressed even more effectively.

The reactive group refers to a group having a carbon-carbon unsaturated bond such as a vinyl group, a hydroxyl group, a glycidyl group, an isocyanate group, an amino group, a carboxyl group, an acid anhydride group, a group having an active ester structure, etc.

In the above formula (1), X2 is preferably a group containing an aromatic skeleton, and more preferably a group represented by the following formula (1b).

In the above formula (1), R1 and R2 may be the same group or different groups.

In the above formula (1), R1 or R2 is preferably a group having a heteroaromatic ring skeleton. In this case, cracks or fractures in the cured product when subjected to thermal shock can be suppressed even more effectively.

The heterocycle means a ring composed of two or more elements, and examples thereof include a pyridine ring, a pyrrole ring, an imidazole ring, a dicyclopentadiene ring, and a thiophene ring.

In the above formula (1), R1 or R2 is preferably a group having an imide skeleton. In this case, cracks or fractures in the cured product when subjected to thermal shock can be suppressed even more effectively.

In the above formula (1), R1 or R2 is preferably a group having a naphthalene skeleton. In this case, cracks or fractures in the cured product when subjected to thermal shock can be suppressed even more effectively.

In the above formula (1), it is preferable that R1, R2, X1, and X2 are each a group that does not have a phosphorus atom. In other words, it is preferable that the first active ester compound does not have a phosphorus atom. In this case, the storage stability of the resin material can be improved, and cracks or cracks in the cured product when subjected to thermal shock can be even more effectively suppressed.

In the above formula (1), R1, R2, X1, and X2 are each preferably a group having no aliphatic hydrocarbon chain with a carbon number of 2 or more and 4 or less, and more preferably a group having no aliphatic hydrocarbon chain with a carbon number of 2 or more. In other words, the first active ester compound preferably has no aliphatic hydrocarbon chain with a carbon number of 2 or more and 4 or less, and more preferably has no aliphatic hydrocarbon chain with a carbon number of 2 or more. In this case, the storage stability of the resin material can be improved, and cracks or cracks in the cured product when subjected to thermal shock can be even more effectively suppressed.

The active ester equivalent of the first active ester compound is preferably 200 eq/g or more, more preferably 210 eq/g or more, even more preferably 220 eq/g or more, and preferably 500 eq/g or less, more preferably 400 eq/g or less, and even more preferably 350 eq/g or less. When the active ester equivalent is equal to or more than the lower limit and equal to or less than the upper limit, the effects of the present invention can be more effectively exhibited.

The content of the first active ester compound relative to 100 parts by weight of the epoxy compound is preferably 70 parts by weight or more, more preferably 85 parts by weight or more, preferably 250 parts by weight or less, more preferably 220 parts by weight or less, even more preferably 150 parts by weight or less, and particularly preferably 120 parts by weight or less. When the content of the first active ester compound is equal to or more than the above lower limit and equal to or less than the above upper limit, the curing property is more excellent, the thermal dimensional stability is further improved, and the volatilization of the remaining unreacted components can be further suppressed.

In 100% by weight of the curing agent, the content of the first active ester compound is preferably 30% by weight or more, more preferably 50% by weight or more, and most preferably 100% by weight (total amount). When the content of the first active ester compound is equal to or more than the lower limit and equal to or less than the upper limit, the effect of the present invention can be more effectively exerted.

<Curing agent X>
The resin material may contain a curing agent that does not have a structure represented by the following formula (X) (hereinafter, may be referred to as "curing agent X"). The curing agent X is a curing agent different from the first active ester compound. Only one type of the curing agent X may be used, or two or more types may be used in combination.

In the above formula (X), R1, R2, and X1 each represent an organic group, X2 represents a group containing an aliphatic chain skeleton, a group containing an aliphatic skeleton, or a group containing an aromatic skeleton, m represents an integer of 1 to 6, and n represents an integer of 1 to 5.

Examples of the curing agent X include cyanate ester compounds (cyanate ester curing agents), amine compounds (amine curing agents), thiol compounds (thiol curing agents), imidazole compounds, phosphine compounds, dicyandiamide, phenolic compounds (phenolic curing agents), acid anhydrides, active ester compounds not having the structure represented by the above formula (X) (active ester curing agents), carbodiimide compounds (carbodiimide curing agents), and benzoxazine compounds (benzoxazine curing agents). It is preferable that the curing agent X has a functional group capable of reacting with the epoxy group of the epoxy compound.

In this specification, the "active ester compound that does not have the structure represented by formula (X)" may be referred to as the "second active ester compound."

The curing agent X is preferably the second active ester compound or the carbodiimide compound. The curing agent preferably contains the second active ester compound, and preferably contains the carbodiimide compound.

The second active ester compound is a compound that contains at least one ester bond and has an aliphatic chain, an aliphatic ring, or an aromatic ring bonded to both sides of the ester bond. The second active ester compound is obtained, for example, by a condensation reaction between a carboxylic acid compound or a thiocarboxylic acid compound and a hydroxy compound or a thiol compound. An example of the second active ester compound is a compound represented by the following formula (2).

In the above formula (2), X1 represents a group containing an aliphatic chain, a group containing an aliphatic ring, or a group containing an aromatic ring, and X2 represents a group containing an aromatic ring. Preferred examples of the group containing an aromatic ring include a benzene ring which may have a substituent, and a naphthalene ring which may have a substituent. X1 is preferably a naphthalene ring. Examples of the substituent include a hydrocarbon group. The number of carbon atoms in the hydrocarbon group is preferably 12 or less, more preferably 6 or less, and even more preferably 4 or less.

In the above formula (2), examples of the combination of X1 and X2 include a combination of a benzene ring which may have a substituent and a benzene ring which may have a substituent, and a combination of a benzene ring which may have a substituent and a naphthalene ring which may have a substituent. Furthermore, examples of the combination of X1 and X2 include a combination of a naphthalene ring which may have a substituent and a naphthalene ring which may have a substituent.

The second active ester compound is not particularly limited. From the viewpoint of improving thermal dimensional stability and flame retardancy, the second active ester compound is preferably an active ester compound having two or more aromatic skeletons. From the viewpoint of lowering the dielectric tangent of the cured product and improving the thermal dimensional stability of the cured product, it is more preferable that the main chain skeleton of the second active ester compound has a naphthalene ring.

The second active ester compound is preferably an active ester compound having no side chain. The curing agent preferably contains an active ester compound having no side chain. In this case, the effect of the present invention can be exerted even more effectively.

The first active ester compound has a side chain (the group represented by X1 in formula (1)), and an active ester compound that does not have a side chain is the second active ester compound.

Commercially available products of the second active ester compound include "HPC-8000-65T," "EXB9416-70BK," "EXB8100-65T," and "HPC-8150-60T," manufactured by DIC Corporation.

The carbodiimide compound is a compound having a structural unit represented by the following formula (3). In the following formula (3), the right end and the left end are bonding sites with other groups. The above carbodiimide compounds may be used alone or in combination of two or more types.

In the above formula (3), X represents an alkylene group, a group in which a substituent is bonded to an alkylene group, a cycloalkylene group, a group in which a substituent is bonded to a cycloalkylene group, an arylene group, or a group in which a substituent is bonded to an arylene group, and p represents an integer of 1 to 5. When there are multiple Xs, the multiple Xs may be the same or different.

In the above formula (3), at least one X is preferably an alkylene group, a group in which a substituent is bonded to an alkylene group, a cycloalkylene group, or a group in which a substituent is bonded to a cycloalkylene group.

Commercially available products of the above carbodiimide compounds include "Carbodilite V-02B", "Carbodilite V-03", "Carbodilite V-04K", "Carbodilite V-07", "Carbodilite V-09", "Carbodilite 10M-SP", and "Carbodilite 10M-SP (modified)" manufactured by Nisshinbo Chemical Co., Ltd., as well as "Stavaxol P", "Stavaxol P400", and "Hi-Kasil 510" manufactured by Rhein Chemie.

Examples of the phenolic compounds include novolac-type phenols, biphenol-type phenols, naphthalene-type phenols, dicyclopentadiene-type phenols, aralkyl-type phenols, and dicyclopentadiene-type phenols.

Commercially available products of the above phenol compounds include novolac type phenols (DIC Corporation's "TD-2091"), biphenyl novolac type phenols (Meiwa Chemical Industry Co., Ltd.'s "MEH-7851"), aralkyl type phenol compounds (Meiwa Chemical Industry Co., Ltd.'s "MEH-7800"), and phenols having an aminotriazine skeleton (DIC Corporation's "LA1356" and "LA3018-50P").

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 phenol novolac type cyanate ester resins (PT-30 and PT-60 manufactured by Lonza Japan) and prepolymers in which bisphenol type cyanate ester resins are trimerized (BA-230S, BA-3000S, BTP-1000S, and BTP-6020S manufactured by Lonza Japan).

Examples of the acid anhydrides include tetrahydrophthalic anhydride and alkylstyrene-maleic anhydride copolymers.

Commercially available products of the above acid anhydrides include "Rikacid TDA-100" manufactured by New Japan Chemical Co., Ltd.

The content of the curing agent X relative to 100 parts by weight of the epoxy compound is preferably 70 parts by weight or more, more preferably 85 parts by weight or more, preferably 150 parts by weight or less, more preferably 120 parts by weight or less. When the content of the curing agent X is equal to or more than the lower limit and equal to or less than the upper limit, the curing property is more excellent, the thermal dimensional stability is further improved, and the volatilization of the remaining unreacted components can be further suppressed.

[Curing accelerator]
The resin material preferably contains a curing accelerator. The use of the curing accelerator further increases 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. The curing accelerator is not particularly limited, and conventionally known curing accelerators can be used. The curing accelerator may be used alone or in combination of two or more.

Examples of the curing accelerator 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 phosphorus compounds and organometallic compounds, and radical curing accelerators such as peroxides.

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. Examples include melitate, 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.

Examples of the amine compounds include diethylamine, triethylamine, diethylenetetramine, triethylenetetramine, and 4,4-dimethylaminopyridine.

Examples of the phosphorus compounds include triphenylphosphine compounds.

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

Examples of the above peroxides include dicumyl peroxide and perhexyl 25B.

From the viewpoint of further reducing the curing temperature and effectively suppressing warping of the cured product, it is preferable that the curing accelerator contains the anionic curing accelerator, and it is more preferable that the curing accelerator contains the imidazole compound.

From the viewpoint of further reducing the curing temperature and effectively suppressing warping of the cured product, the content of the anionic curing accelerator in 100% by weight of the curing accelerator is preferably 20% by weight or more, more preferably 50% by weight or more, even more preferably 70% by weight or more, and most preferably 100% by weight (total amount). Therefore, it is most preferable that the curing accelerator is the anionic curing accelerator.

The content of the curing accelerator is not particularly limited. The content of the curing accelerator is preferably 0.01% by weight or more, more preferably 0.05% by weight or more, preferably 5% by weight or less, more preferably 3% by weight or less, based on 100% by weight of the components in the resin material excluding the inorganic filler and the solvent. When the content of the curing accelerator is equal to or more than the lower limit and equal to or less than the upper limit, the resin material is cured efficiently. When the content of the curing accelerator is within a more preferred range, the storage stability of the resin material is further increased, and a better cured product is obtained.

[Bismaleimide compound]
The resin material preferably contains a bismaleimide compound. The bismaleimide compound is not particularly limited. The bismaleimide compound has a maleimide group. As the bismaleimide compound, a conventionally known bismaleimide compound can be used. The bismaleimide compound includes a citraconic imide compound. The citraconic imide compound is a compound in which a methyl group is bonded to one of the carbon atoms constituting the double bond between carbon atoms in a maleimide group. The bismaleimide compound may be used alone or in combination of two or more kinds.

The bismaleimide compound preferably has a skeleton derived from the dimer diamine at both ends of the main chain. In this case, the bismaleimide compound may have a skeleton derived from the dimer diamine at both ends of the main chain and in the skeleton other than both ends of the main chain, or may have a skeleton derived from the dimer diamine only at both ends of the main chain. When the bismaleimide compound has a skeleton derived from the dimer diamine, the skeletons derived from the dimer diamine tend to associate with each other, forming a phase separation structure, which effectively increases the glass transition temperature of the cured product of the resin material. This makes it possible to further increase the thermal dimensional stability of the cured product, and further increase the adhesion between the insulating layer and the metal layer.

The above bismaleimide compounds include aromatic bismaleimide compounds and aliphatic bismaleimide compounds.

Examples of the aliphatic bismaleimide compounds include N-alkyl bismaleimide compounds.

From the viewpoint of lowering the dielectric tangent and keeping the curing temperature low, the above bismaleimide compound is preferably an N-alkyl bismaleimide compound.

From the viewpoint of further lowering the dielectric tangent of the cured product and further increasing the adhesion between the insulating layer and the metal layer, it is preferable that the N-alkylbismaleimide compound has a structure in which an aliphatic skeleton is bonded to the nitrogen atom in the maleimide group. Also, from the viewpoint of improving etching performance, it is preferable that the N-alkylbismaleimide compound has an imide bond or a dimer diamine skeleton, and it is preferable that the N-alkylbismaleimide compound has both an imide bond and a dimer diamine skeleton.

From the viewpoint of further reducing the dielectric tangent, it is more preferable that the N-alkyl bismaleimide compound is an N-alkyl bismaleimide compound having a skeleton derived from dimer diamine. In the N-alkyl bismaleimide compound having a skeleton derived from dimer diamine, the dimer diamine skeleton exists as a partial skeleton.

The bismaleimide compound can be obtained, for example, by reacting a tetracarboxylic dianhydride with a diamine compound to obtain a reaction product, and then reacting the reaction product with maleic anhydride.

In addition, a bismaleimide compound having a skeleton derived from the above dimer diamine only at both ends of the main chain can be obtained, for example, as follows. A tetracarboxylic acid dianhydride, a dimer diamine, and a diamine compound other than dimer diamine are reacted to obtain a first reactant. The obtained first reactant is reacted with dimer diamine to obtain a second reactant. The obtained second reactant is reacted with maleic anhydride.

The N-alkylbismaleimide compound having a skeleton derived from the above dimer diamine can be obtained, for example, by reacting a tetracarboxylic dianhydride with a dimer diamine to obtain a reaction product, and then reacting the reaction product with maleic anhydride.

Examples of the tetracarboxylic dianhydride 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)diphenylsulfonyl tetracarboxylic dianhydride, and 4,4'-bis(3,4-dicarboxyphenoxy)diphenylsulfonyl tetracarboxylic dianhydride. dianhydride, 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'-diphenyl ether dianhydride, and bis(triphenylphthalic acid)-4,4'-diphenylmethane dianhydride are examples of such anhydrides.

The diamine compounds include 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, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), 1,4-diaminobutane, 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, and dimer diamine.

The above diamine compound is preferably a diamine compound having an alicyclic skeleton, since the effects of the present invention are more excellent. In this case, the above bismaleimide compound may have a skeleton derived from a reaction product of a tetracarboxylic dianhydride and a diamine compound having an aliphatic skeleton, or may have a skeleton derived from a reaction product of a tetracarboxylic dianhydride, a diamine compound having an aliphatic skeleton, and an amine compound other than the diamine compound having an aliphatic skeleton. In addition, the above bismaleimide compound may have diamine skeletons at both ends derived from the diamine compound having the aliphatic skeleton, and diamine skeletons other than those at both ends derived from a diamine compound having an aromatic skeleton.

Examples of the dimer diamine include VERSAMINE 551 (product name, manufactured by BASF Japan, 3,4-bis(1-aminoheptyl)-6-hexyl-5-(1-octenyl)cyclohexene), VERSAMINE 552 (product name, manufactured by Cognix Japan, hydrogenated VERSAMINE 551), and PRIAMINE 1075 and PRIAMINE 1074 (product names, both manufactured by Croda Japan).

Commercially available N-alkyl bismaleimide compounds include "BMI-1500," "BMI-1700," and "BMI-3000" manufactured by Designer Molecules Inc.

The molecular weight of the bismaleimide compound is preferably 500 or more, more preferably 1000 or more, and preferably less than 20000, more preferably less than 15000. When the molecular weight of the bismaleimide compound is equal to or more than the lower limit and less than the upper limit, the dielectric tangent of the cured product can be further reduced and the adhesion between the insulating layer and the metal layer can be further improved. When the molecular weight of the bismaleimide compound is less than the upper limit, the embeddability of the resin material in unevenness of the substrate, etc. can be further improved.

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

The content of the bismaleimide compound in the resin material (100% by weight, excluding the solvent) is preferably 3% by weight or more, more preferably 5% by weight or more, and preferably 25% by weight or less, more preferably 20% by weight or less, and particularly preferably 15% by weight or less. When the content of the bismaleimide compound is equal to or more than the lower limit and equal to or less than the upper limit, the sea-island structure can be formed more easily, the dielectric tangent can be further lowered, and the thermal dimensional stability, the elastic modulus, and the adhesion between the insulating layer and the metal layer can be further improved.

The content of the bismaleimide compound in the resin material (100% by weight, excluding inorganic fillers and solvents) is preferably 15% by weight or more, more preferably 20% by weight or more, and preferably 65% by weight or less, more preferably 50% by weight or less, and particularly preferably 40% by weight or less. When the content of the bismaleimide compound is equal to or more than the lower limit and equal to or less than the upper limit, the sea-island structure can be formed more easily, the dielectric tangent can be further lowered, and the thermal dimensional stability, the elastic modulus, and the adhesion between the insulating layer and the metal layer can be further improved.

[Thermoplastic resin]
The resin material preferably contains a thermoplastic resin. Examples of the thermoplastic resin include polyvinyl acetal resin, polyimide resin, and phenoxy resin. Only one type of thermoplastic resin may be used, or two or more types may be used in combination.

From the viewpoint of effectively lowering the dielectric tangent and effectively increasing the adhesion of metal wiring regardless of the curing environment, the thermoplastic resin is preferably a phenoxy resin. The use of phenoxy resin prevents the resin film from becoming less able to fill holes or irregularities in the circuit board and prevents the inorganic filler from becoming non-uniform. In addition, the use of phenoxy resin improves the dispersibility of the inorganic filler because the melt viscosity can be adjusted, and the resin composition or B-stage product is less likely to wet and spread to unintended areas during the curing process.

The phenoxy resin contained in the resin material is not particularly limited. Any conventionally known phenoxy resin can be used as the phenoxy resin. Only one type of the phenoxy resin may be used, or two or more types may be used in combination.

Examples of the phenoxy resin include phenoxy resins having a skeleton such as a bisphenol A skeleton, a bisphenol F skeleton, a bisphenol S skeleton, a biphenyl skeleton, a novolac skeleton, a naphthalene skeleton, and an imide skeleton.

Commercially available examples of the above phenoxy resins include "YP50", "YP55" and "YP70" manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd., and "1256B40", "4250", "4256H40", "4275", "YX6954BH30" and "YX8100BH30" manufactured by Mitsubishi Chemical Corporation.

From the viewpoint of improving handling properties, plating peel strength at low roughness, and adhesion between the insulating layer and the metal layer, the thermoplastic resin is preferably a polyimide resin (polyimide compound).

From the viewpoint of improving solubility, the polyimide compound is preferably a polyimide compound obtained by reacting a tetracarboxylic dianhydride with a dimer diamine.

Examples of the tetracarboxylic dianhydride 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)diphenylsulfonyl tetracarboxylic dianhydride, and 4,4'-bis(3,4-dicarboxyphenoxy)diphenylsulfonyl tetracarboxylic dianhydride. dianhydride, 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'-diphenyl ether dianhydride, and bis(triphenylphthalic acid)-4,4'-diphenylmethane dianhydride are examples of such anhydrides.

Examples of the dimer diamine include VERSAMINE 551 (product name, manufactured by BASF Japan, 3,4-bis(1-aminoheptyl)-6-hexyl-5-(1-octenyl)cyclohexene), VERSAMINE 552 (product name, manufactured by Cognix Japan, hydrogenated VERSAMINE 551), PRIAMINE 1075, and PRIAMINE 1074 (product names, all manufactured by Croda Japan).

The polyimide compound may have an acid anhydride structure, a maleimide structure, or a citraconic imide structure at the end. In this case, the polyimide compound can be reacted with an epoxy resin. By reacting the polyimide compound with an epoxy resin, the thermal dimensional stability of the cured product can be improved.

From the viewpoint of obtaining a resin material with even better storage stability, the weight average molecular weight of the thermoplastic resin, the polyimide resin, and the phenoxy resin is preferably 5,000 or more, more preferably 10,000 or more, and preferably 100,000 or less, more preferably 50,000 or less.

The weight average molecular weights of the thermoplastic resin, the polyimide resin, and the phenoxy resin are polystyrene-equivalent weight average molecular weights measured by gel permeation chromatography (GPC).

The contents of the thermoplastic resin, the polyimide resin, and the phenoxy resin are not particularly limited. In 100% by weight of the components excluding the inorganic filler and the solvent in the resin material, the content of the thermoplastic resin (when the thermoplastic resin is a polyimide resin or a phenoxy resin, the content of the polyimide resin or the phenoxy resin) is preferably 1% by weight or more, more preferably 2% by weight or more, preferably 30% by weight or less, more preferably 20% by weight or less. When the content of the thermoplastic resin is equal to or more than the lower limit and equal to or less than the upper limit, the resin material is better able to fill holes or irregularities in the circuit board. When the content of the thermoplastic resin is equal to or more than the lower limit, the formation of the resin film becomes easier, and a better insulating layer is obtained. When the content of the thermoplastic resin is equal to or less than the upper limit, the thermal expansion coefficient of the cured product becomes even lower. When the content of the thermoplastic resin is equal to or less than the upper limit, the surface roughness of the surface of the cured product becomes even smaller, and the adhesive strength between the cured product and the metal layer becomes even higher.

[solvent]
The resin material does not contain or contains 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 the inorganic filler. Only one type of the solvent may be used, or two or more types may be used in combination.

The above-mentioned 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.

It is preferable that most of the solvent is 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 content of the solvent in the resin composition is not particularly limited. The content of the solvent can be changed as appropriate, taking into account the coatability of the resin composition, etc.

When 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 10% by weight or less, more preferably 5% by weight or less.

[Other ingredients]
For the purpose of improving impact resistance, heat resistance, resin compatibility, workability, and the like, the resin material may contain a leveling agent, a flame retardant, a coupling agent, a colorant, an antioxidant, an ultraviolet degradation inhibitor, a defoaming agent, a thickener, a thixotropy imparting agent, a thermosetting resin other than the epoxy compound, and the like.

Examples of the coupling agent include silane coupling agents, titanium coupling agents, and aluminum coupling agents. Examples of the silane coupling agent include vinyl silane, amino silane, imidazole silane, and epoxy silane.

Other examples of the above-mentioned thermosetting resins include polyphenylene ether resin, divinyl benzyl ether resin, polyarylate resin, diallyl phthalate resin, benzoxazine resin, benzoxazole resin, and acrylate resin.

(Other details of resin material)
The melt viscosity of the resin material at 100° C. is preferably 5 Pa·s or more, more preferably 10 Pa·s or more, and preferably 500 Pa·s or less, more preferably 400 Pa·s or less. When the melt viscosity is equal to or more than the lower limit and equal to or less than the upper limit, the storage stability can be further improved.

The melt viscosity of the above resin material at 100°C is determined by measuring the dynamic viscoelasticity using a Rheometer device (e.g., AR-2000 manufactured by TA Instruments) under the following conditions: frequency 6.28 rad/sec, starting temperature 60°C, measurement interval temperature 2.5°C, heating rate 5°C/min, and strain 21.8%.

(Resin film)
The above-mentioned resin composition is molded into a film to obtain a resin film (B-stage product/B-stage film). The above-mentioned 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 at, for example, 50°C to 150°C for 1 to 10 minutes to a degree that does not cause excessive curing due to heat, 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 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.

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

From the viewpoint of controlling the degree of cure 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.

(Semiconductor device, printed wiring board, copper-clad laminate, and multilayer printed wiring board)
The above-mentioned resin material is suitably used for forming a molding resin in which a semiconductor chip is embedded in a semiconductor device.

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

The printed wiring board is obtained, for example, by heating and pressurizing the resin material.

A laminated member having a metal layer on one or both sides can be laminated onto the resin film. A laminated structure can be suitably obtained, which includes a laminated member having a metal layer on its surface and a resin film laminated on the surface of the metal layer, the resin film being the resin material described above. There is no particular limitation on the method for laminating the resin film and the laminated member having the metal layer on its surface, and any known method can be used. For example, the resin film can be laminated onto the laminated member having a metal layer on its surface 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 lamination target component having the above-mentioned 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 a copper foil and a resin film laminated on one surface of the copper foil.

The thickness of the copper foil of the copper-clad laminate is not particularly limited. The thickness of the copper foil is preferably within the range of 1 μm to 50 μm. 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.

The above resin materials are suitable for use in producing multilayer substrates.

One 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 formed from the resin material. The insulating layer of the multilayer board may also be formed from the resin film of the laminate film using a laminate film. The insulating layer is preferably laminated on the surface of the circuit board on which the circuits are provided. A portion 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.

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. The insulating layer is preferably 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, the copper foil is preferably etched to form a copper circuit.

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

Among multilayer substrates, multilayer printed wiring boards require a low dielectric tangent and high insulation reliability from the insulating layer. The resin material of the present invention has a low dielectric tangent and is less likely to crack or break in the cured product even when subjected to thermal shock, so that insulation reliability can be effectively improved. Therefore, the resin material of the present invention is suitable for use in forming an insulating layer in a multilayer printed wiring board.

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. At least one of the insulating layers is a cured product of the resin material.

Figure 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, multiple 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 multiple 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 the cured product of the 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).

(Roughening treatment and swelling treatment)
The resin material is preferably used to obtain a cured product to be subjected to roughening treatment or desmear treatment. The cured product also includes a pre-cured product that can be further cured.

In order to form fine irregularities on the surface of the cured product obtained by pre-curing the resin material, the cured product is preferably subjected to a roughening treatment. Before the roughening treatment, the cured product is preferably subjected to a swelling treatment. After the pre-curing and before the roughening treatment, the cured product is preferably subjected to a swelling treatment, and is further preferably cured after the roughening treatment. However, the cured product does not necessarily have to be subjected to a swelling treatment.

The swelling treatment may be carried out by treating the cured product with an aqueous solution or an organic solvent dispersion of a compound mainly composed of ethylene glycol. The swelling liquid used in the swelling treatment generally contains an alkali as a pH adjuster. The swelling liquid preferably contains sodium hydroxide. Specifically, the swelling treatment is carried out by treating the cured product with a 40% by weight aqueous solution of ethylene glycol at a treatment temperature of 30°C to 85°C for 1 to 30 minutes. The temperature of the swelling treatment is preferably within the range of 50°C to 85°C. If the temperature of the swelling treatment is too low, the swelling treatment takes a long time and the adhesive strength between the cured product and the metal layer tends to be lower.

In the above roughening treatment, a chemical oxidizing agent such as a manganese compound, a chromium compound, or a persulfate compound is used. These chemical oxidizing agents are used as an aqueous solution or an organic solvent dispersion solution after water or an organic solvent is added. The roughening liquid used in the roughening treatment generally contains an alkali as a pH adjuster or the like. The roughening liquid preferably contains sodium hydroxide.

The manganese compounds include potassium permanganate and sodium permanganate. The chromium compounds include potassium dichromate and potassium chromate anhydride. The persulfate compounds include sodium persulfate, potassium persulfate, and ammonium persulfate.

The arithmetic mean roughness Ra of the surface of the cured product is preferably 10 nm or more, and is preferably less than 300 nm, more preferably less than 200 nm, and even more preferably less than 150 nm. In this case, the adhesive strength between the cured product and the metal layer is increased, and even finer wiring is formed on the surface of the insulating layer. The arithmetic mean roughness Ra is measured in accordance with JIS B0601:1994.

(Desmearing)
Through holes may be formed in the cured product obtained by pre-curing the resin material. In the multilayer board, etc., vias or through holes are formed as the through holes. For example, vias can be formed by irradiating a laser such as a _CO2 laser. The diameter of the via is not particularly limited, but is about 60 μm to 80 μm. Due to the formation of the through holes, smears, which are resin residues derived from the resin components contained in the cured product, are often formed at the bottom of the via.

In order to remove the smears, the surface of the cured product is preferably subjected to a desmear treatment. The desmear treatment may also serve as a roughening treatment.

In the desmear treatment, a chemical oxidizing agent such as a manganese compound, a chromium compound, or a persulfate compound is used, as in the roughening treatment. These chemical oxidizing agents are used as an aqueous solution or an organic solvent dispersion solution after water or an organic solvent is added. The desmear treatment liquid used in the desmear treatment generally contains an alkali. The desmear treatment liquid preferably contains sodium hydroxide.

By using the above resin material, the surface roughness of the desmeared cured product is sufficiently small.

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

The following materials were prepared:

(Epoxy Compound)
Biphenyl-type epoxy compound ("NC-3000" manufactured by Nippon Kayaku Co., Ltd., solid at 25°C)
Naphthol aralkyl type epoxy compound ("ESN-475V" manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd., solid at 25°C)
Dicyclopentadiene type epoxy compound (ADEKA Corporation "EP-4088S", viscosity at 25°C 230 mPa·s)
Glycidylamine type epoxy compound ("GAN" manufactured by Nippon Kayaku Co., Ltd., viscosity at 25°C: 130 mPa·s)

(Inorganic filler)
Silica-containing slurry (75% silica by weight: Admatechs "SC4050-HOA", average particle size 1.0 μm, aminosilane treatment, cyclohexanone 25% by weight)

(Hardening agent)
<First active ester compound>
Active ester compound 1 (active ester equivalent: 270 eq/g)
Active ester compound 2 (active ester equivalent: 305 eq/g)
Active ester compound 3 (active ester equivalent: 265 eq/g)
Active ester compound 4 (active ester equivalent: 315 eq/g)
Active ester compound 5 (active ester equivalent: 290 eq/g)
Active ester compound 6 (active ester equivalent: 288 eq/g)

Active ester compound 1 was synthesized according to Synthesis Example 1 below.

<Synthesis Example 1>
In a flask equipped with a thermometer, a dropping funnel, a cooling tube, a fractionating tube, and a stirrer, 320 g (2.0 mol) of 2,7-dihydroxynaphthalene, 301 g (1.7 mol) of cyclohexylmethyl bromide, and 5.0 g of paratoluenesulfonic acid monohydrate were placed and stirred at room temperature while blowing in nitrogen. The mixture was then heated to 150°C and stirred for 4 hours while distilling off the water produced. After the reaction was completed, 900 g of methyl isobutyl ketone and 5.4 g of a 20% aqueous sodium hydroxide solution were added for neutralization, and the aqueous layer was removed by separation, washed three times with 280 g of water, and methyl isobutyl ketone was removed under reduced pressure to obtain 470 g of a cyclohexylmethyl-modified naphthalene compound. The obtained cyclohexylmethyl-modified naphthalene compound was a black solid. The hydroxyl equivalent of the obtained cyclohexylmethyl-modified naphthalene compound was 185 g/equivalent.

203.0g of isophthalic acid chloride (molar number of acid chloride groups: 2.0 mol) and 1400g of toluene were placed in a flask equipped with a thermometer, a dropping funnel, a cooling tube, a distillation tube, and a stirrer, and the system was reduced in pressure and replaced with nitrogen to dissolve. Next, 72.4g (0.67 mol) of benzyl alcohol and 246g of the obtained cyclohexyl-modified naphthalene compound (molar number of phenolic hydroxyl groups: 1.33 mol) were added, and the system was reduced in pressure and replaced with nitrogen to dissolve. Then, 0.70g of tetrabutylammonium bromide was dissolved, and while applying nitrogen gas purge, the system was controlled to 60°C or less, and 400g of 20% aqueous sodium hydroxide solution was dropped over 3 hours. Then, stirring was continued under these conditions for 1.0 hour. After the reaction was completed, the mixture was left to stand and separated, and the aqueous layer was removed. Next, water was added to the toluene layer in which the reactants were dissolved, and the mixture was stirred and mixed for 15 minutes, then allowed to stand and separated to remove the aqueous layer. This operation was repeated until the pH of the aqueous layer reached 7. The water was then removed by decanting to obtain active ester compound 1 in a toluene solution state with a non-volatile content of 65% by weight. The viscosity of this toluene solution with a non-volatile content of 65% by weight was 12,000 mPa·s (25°C). In addition, the softening point after drying was 146°C.

The obtained active ester compound 1 was an active ester compound having a structure represented by the above formula (1). It was confirmed that the obtained active ester compound 1 contains an active ester compound in which, in the above formula (1), R1 and R2 are benzyl groups, X1 is an organic group having no aromatic skeleton and six carbon atoms, X2 is a group having a naphthalene skeleton, m is 2, and n is 1.

Active ester compound 2 was synthesized according to Synthesis Example 2 below.

<Synthesis Example 2>
In the same manner as in Synthesis Example 1, a cyclohexylmethyl-modified naphthalene compound was obtained.

Except for changing 72.4 g (0.67 mol) of benzyl alcohol to 96.0 g (0.67 mol) of α-naphthol, the same procedure as in Synthesis Example 1 was followed to obtain active ester compound 2 in the form of a toluene solution with a non-volatile content of 65% by weight. The viscosity of this toluene solution with a non-volatile content of 65% by weight was 15,000 mPa·s (25°C). In addition, the softening point after drying was 150°C.

The obtained active ester compound 2 was an active ester compound having a structure represented by the above formula (1). It was confirmed that the obtained active ester compound 2 contains an active ester compound in which, in the above formula (1), R1 and R2 are naphthyl groups, X1 is an organic group having no aromatic skeleton and 6 carbon atoms, X2 is a group having a naphthalene skeleton, m is 2, and n is 1.

Active ester compound 3 was synthesized according to Synthesis Example 3 below.

<Synthesis Example 3>
The same procedure as in Synthesis Example 2 (matching the number of moles of phenolic hydroxyl groups) was carried out except that 301 g (1.7 mol) of cyclohexylmethyl bromide was replaced with 290 g (1.7 mol) of benzyl bromide to obtain a benzyl-modified naphthalene compound, and active ester compound 3 in the form of a toluene solution with a non-volatile content of 65% by weight was obtained. The viscosity of this toluene solution with a non-volatile content of 65% by weight was 16000 mPa·s (25°C). In addition, the softening point after drying was 157°C.

The obtained active ester compound 3 was an active ester compound having a structure represented by the above formula (1). It was confirmed that the obtained active ester compound 3 included an active ester compound in which R1 and R2 are naphthyl groups, X1 is a benzyl group, X2 is a group having a naphthalene skeleton, m is 2, and n is 1 in the above formula (1).

Active ester compound 4 was synthesized according to Synthesis Example 4 below.

<Synthesis Example 4>
Except for changing 301 g (1.7 mol) of cyclohexylmethyl bromide to 376 g (1.7 mol) of 1-naphthylmethyl bromide, the same procedure as in Synthesis Example 2 (matching the number of moles of phenolic hydroxyl groups) was carried out to obtain active ester compound 4 in the form of a toluene solution with a non-volatile content of 65% by weight. The viscosity of this toluene solution with a non-volatile content of 65% by weight was 17000 mPa s and the softening point was 163°C.

The obtained active ester compound 4 was an active ester compound having a structure represented by the above formula (1). It was confirmed that the obtained active ester compound 4 contained an active ester compound in which R1 and R2 are naphthyl groups, X1 is a naphthyl group, X2 is a group having a naphthalene skeleton, m is 2, and n is 1 in the above formula (1).

Active ester compound 5 was synthesized according to Synthesis Example 5 below.

<Synthesis Example 5>
Except for changing 301 g (1.7 mol) of cyclohexylmethyl bromide to 335 g (1.7 mol) of 3-(bromomethyl)styrene, the same procedure as in Synthesis Example 2 (matching the number of moles of phenolic hydroxyl groups) was followed to obtain active ester compound 5 in the form of a toluene solution with a non-volatile content of 65% by weight. The viscosity of this toluene solution with a non-volatile content of 65% by weight was 16000 mPa s and the softening point was 152°C.

The obtained active ester compound 5 was an active ester compound having a structure represented by the above formula (1). It was confirmed that the obtained active ester compound 5 includes an active ester compound in which, in the above formula (1), R1 and R2 are naphthyl groups, X1 is a styryl group, X2 is a group having a naphthalene skeleton, m is 2, and n is 2.

Active ester compound 6 was synthesized according to Synthesis Example 6 below.

<Synthesis Example 6>
Except for changing 301 g (1.7 mol) of cyclohexylmethyl bromide to 233 g (1.7 mol) of 1-bromobutane, the same procedure as in Synthesis Example 2 (matching the number of moles of phenolic hydroxyl groups) was followed to obtain active ester compound 7 in the form of a toluene solution with a non-volatile content of 65% by weight. The viscosity of this toluene solution with a non-volatile content of 65% by weight was 14,000 mPa s and the softening point was 135° C.

The obtained active ester compound 6 was an active ester compound having a structure represented by the above formula (1). It was confirmed that the obtained active ester compound 6 contained an active ester compound in which R1 and R2 are naphthyl groups, X1 is a butyl group, X2 is a group having a naphthalene skeleton, m is 2, and n is 1 in the above formula (1).

<Curing agent X>
Active ester compound without side chains (DIC Corporation "HPC-8000-65T")
Aminotriazine phenol (DIC Corporation "LA1356")
Carbodiimide compound-containing liquid (Nisshinbo Chemical's "V-03", solid content 50% by weight)

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

(Bismaleimide compounds)
Bismaleimide compound ("BMI-3000J" manufactured by Designor Molecular Systems, Inc. (DMI))

(Thermoplastic resin)
Phenoxy resin (Mitsubishi Chemical Corporation "YX-6954")
Polyimide resin synthesized according to Synthesis Example A below

(Synthesis Example A)
In a reaction vessel equipped with a stirrer, a water divider, a thermometer, and a nitrogen gas inlet tube, 300.0 g of tetracarboxylic dianhydride ("BisDA-1000" manufactured by SABIC Japan LLC) and 665.5 g of cyclohexanone were placed, and the solution in the vessel was heated to 60°C. Then, 137.4 g of 4,4'-methylenebis(2-methylcyclohexylamine) (manufactured by Tokyo Chemical Industry Co., Ltd., aliphatic structure with 15 carbon atoms) was dropped. Then, 121.0 g of methylcyclohexane and 423.5 g of ethylene glycol dimethyl ether were placed, and an imidization reaction was carried out at 140°C for 10 hours to obtain a polyimide resin-containing solution (non-volatile content 26.6 wt%). The molecular weight (weight average molecular weight) of the obtained polyimide resin was 20,000. The molar ratio of the acid component/amine component was 1.04.

The molecular weight of the polyimide resin synthesized in Synthesis Example A was determined as follows.

GPC (Gel Permeation Chromatography) Measurement:
Using a high performance liquid chromatograph system manufactured by Shimadzu Corporation, measurements were performed at a column temperature of 40°C and a flow rate of 1.0 ml/min, with tetrahydrofuran (THF) as the developing medium. An "SPD-10A" was used as the detector, and two "KF-804L" columns (exclusion limit molecular weight 400,000) manufactured by Shodex Corporation were used in series. "TSK Standard Polystyrene" manufactured by Tosoh Corporation was used as the standard polystyrene, and a calibration curve was created using substances with weight average molecular weights Mw = 354,000, 189,000, 98,900, 37,200, 17,100, 9,830, 5,870, 2,500, 1,050, and 500, and the molecular weight was calculated.

( Reference Examples 1 to 6, Example 7, Reference Examples 8, 9, Example 10, Reference Examples 11 to 15, Comparative Examples 1 to 4)
The components shown in Tables 1 to 3 below were mixed in the amounts (unit: parts by weight of solid content) shown in Tables 1 to 3 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 PET film ("XG284" manufactured by Toray Industries, Inc., 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) Storage stability (1-1) Melt viscosity at 100°C (melt viscosity before storage and storage stability of melt viscosity)
The melt viscosity of the obtained resin film at 100° C. was determined by measuring the dynamic viscoelasticity using a Rheometer device ("AR-2000" manufactured by TA Instruments) under the conditions of a frequency of 6.28 rad/sec, a starting temperature of 60° C., a measurement interval temperature of 2.5° C., a heating rate of 5° C./min, and a strain of 21.8%. The obtained melt viscosity was taken as the melt viscosity before storage.

The obtained resin film was stored at 25°C for 50 hours. The melt viscosity of the resin film after storage was measured in the same manner as above. The obtained melt viscosity was defined as the melt viscosity after storage.

The ratio of the melt viscosity after storage to the melt viscosity before storage (melt viscosity after storage/melt viscosity before storage) was calculated.

[Criteria for determining melt viscosity before storage]
A: The melt viscosity before storage is 5 Pa·s or more and 500 Pa·s or less. B: The melt viscosity before storage is less than 5 Pa·s or more than 500 Pa·s.

[Criteria for determining storage stability of melt viscosity]
A: The ratio (melt viscosity after storage/melt viscosity before storage) is less than 2. B: The ratio (melt viscosity after storage/melt viscosity before storage) is 2 or more and less than 3. C: The ratio (melt viscosity after storage/melt viscosity before storage) is 3 or more.

Regarding the melt viscosity before storage, the result of A is relatively better than the result of B. Regarding the storage stability of the melt viscosity, the result of A is relatively better than the result of B, and the result of B is relatively better than the result of C.

(1-2) Pattern embedding property A copper-clad laminate (a laminate of a glass epoxy substrate having a thickness of 150 μm and a copper foil having a thickness of 35 μm) was prepared. The copper foil was etched to prepare 26 copper patterns having an L/S of 50 μm/50 μm and a length of 1 cm, and an uneven substrate was obtained. On both sides of the obtained uneven substrate, the resin film (B stage film) side of the laminate film was laminated on the copper-clad laminate using a batch vacuum laminator MVLP-500/600-IIA manufactured by Meiki Seisakusho Co., Ltd. The lamination conditions were as follows: the pressure was reduced for 30 seconds to a pressure of 13 hPa or less, and then the pressure was pressed at 100° C. and a pressure of 0.4 MPa for 30 seconds. In this way, a laminate in which a resin film was laminated on an uneven substrate was obtained. After peeling off the PET film, the concave portions of the uneven substrate were observed using an optical microscope to confirm whether the resin film was floating in the concave portions.

A similar evaluation was also performed on resin films stored at 25°C for 50 hours.

[Criteria for determining pattern embeddability]
◯: No lifting occurred on the resin film before and after storage. △: 3 or less lifting occurred on the resin film before and after storage. ×: More than 3 lifting occurred on the resin film before or after storage.

(1-3) FLS (Fine Line and Space (Fine Wiring Formability))
1) Lamination process:
A double-sided copper-clad laminate (copper foil thickness on each side: 18 μm, substrate thickness: 0.7 mm, substrate size: 100 mm×100 mm, Hitachi Chemical Co., Ltd., “MCL-E679FG”) was prepared. Both sides of the foil surface were immersed in "Cz8101" manufactured by MEC Co., Ltd. to roughen the copper foil surface. The resin film (B-stage film) side of the laminated film was laminated onto a copper-clad laminate using "-500/600-IIA". The lamination conditions were: decompression for 30 seconds to a pressure of 13 hPa or less; Thereafter, the resin film was pressed for 30 seconds at 100° C. and a pressure of 0.4 MPa. After the PET film was peeled off, the resin film was heated at 130° C. for 60 minutes to be semi-cured (preliminary cured). In this manner, a laminate (1) was obtained in which a semi-cured resin film was laminated on a CCL substrate.

2) Via hole forming process:
Using a _CO2 laser processing machine (Via Mechanics'"LC-4KF212"), via holes with a diameter of approximately 60 μm were formed under the conditions of burst mode, energy of 0.4 mJ, pulse of 27 μsec, and 3 shots.

3) Desmearing and roughening treatment:
3-1) Swelling treatment:
The obtained laminate (1) 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.

3-2) Permanganate treatment (roughening treatment and desmear treatment):
The laminate (1) 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, the laminate was treated for 2 minutes using a cleaning solution ("Reduction Securigant P" manufactured by Atotech Japan) at 25° C., and then washed with pure water to obtain a roughening-treated laminate (1).

4) Electroless plating process:
The surface of the cured laminate (1) after the roughening treatment was treated with an alkaline cleaner at 60°C ("Cleaner Securigant 902" manufactured by Atotech Japan) for 5 minutes, and degreased and washed. After washing, the cured product was treated with a pre-dip liquid at 25°C ("Pre-dip Neogant B" manufactured by Atotech Japan) for 2 minutes. Thereafter, the cured product was treated with an activator liquid at 40°C ("Activator Neogant 834" manufactured by Atotech Japan) for 5 minutes to attach a palladium catalyst. Next, the cured product was treated with a reducing liquid at 30°C ("Reducer Neogant WA" manufactured by Atotech Japan) for 5 minutes.

Then, the cured material was placed in a chemical copper solution (Atotech Japan's "Basic Printganth MSK-DK", "Copper Printganth MSK", "Stabilizer Printganth MSK", and "Reducer Cu") and electroless plating was performed until the plating thickness reached approximately 0.5 μm. After electroless plating, the material was annealed at 120°C for 30 minutes to remove any remaining hydrogen gas. All steps up to the electroless plating step were performed using 2 L of treatment solution in a beaker scale while the cured material was agitated.

5) Resist formation:
A dry film resist ("RY5125" manufactured by Hitachi Chemical Co., Ltd.) was applied using a hot roll laminator. The lamination conditions were a temperature of 100°C, a pressure of 0.4 MPa, and a lamination speed of 1.5 m/min, and then the laminate was held for 15 minutes. Next, the laminate was exposed to light at 85 mJ/ ^cm2 through a pattern mask with L/S = 10 μm and L/S = 20 μm using a UV exposure machine ("EXA-1201" manufactured by Oak Seisakusho Co., Ltd.), and then developed by spraying a 1 wt% aqueous sodium carbonate solution at 27°C with a spray pressure of 1.2 MPa for 30 seconds.

6) Electrolytic plating treatment:
Next, electrolytic plating was performed on the electroless plated cured product until the plating thickness reached 25 μm. For electrolytic copper plating, a copper sulfate solution ("Copper Sulfate Pentahydrate" manufactured by Wako Pure Chemical Industries, Ltd., "Sulfuric Acid" manufactured by Wako Pure Chemical Industries, Ltd., "Basic Leveler Cupracid HL" manufactured by Atotech Japan, and "Correction Agent Cupracid GS" manufactured by Atotech Japan) was used, and electrolytic plating was performed by passing a current of 0.6 A/ ^cm2 until the plating thickness reached about 25 μm.

7) DFR Stripping and Etching Process:
The dry film resist (DFR) was stripped by spraying with a 3 wt % aqueous solution of sodium hydroxide, followed by quick etching with a sulfuric acid-based acid etching solution ("SAC Process" manufactured by JCU Corporation).

8) Main curing step:
Heated at 190° C. for 1.5 hours.

In this way, evaluation sample A was produced, in which wiring was formed on the cured resin film.

The resin film stored at 25°C for 50 hours was also subjected to steps 1) to 8) above to produce evaluation sample B in which wiring was formed on the cured resin film after storage.

The wiring formation of evaluation sample A and evaluation sample B was observed using a scanning electron microscope (SEM).

[FLS Criteria]
◯: In evaluation sample A and evaluation sample B, it is possible to form L/S=10 μm. △: In evaluation sample A and evaluation sample B, it is impossible to form L/S=10 μm, but it is possible to form L/S=20 μm. ×: In evaluation sample A or evaluation sample B, it is impossible to form L/S=20 μm.

(2) Dielectric loss tangent The obtained resin film was cut into a size of 2 mm wide and 80 mm long, and five sheets were stacked together to obtain a laminate with a thickness of 200 μm. The obtained laminate was heated at 190° C. for 90 minutes to obtain a cured product. The dielectric loss tangent of the obtained cured product was measured at room temperature (23° C.) and a frequency of 1.0 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 tangent]
○: Dielectric loss tangent is 0.005 or less △: Dielectric loss tangent is more than 0.005 and less than 0.01 ×: Dielectric loss tangent is more than 0.01

(3) Thermal shock test The PET film of the obtained laminated film was peeled off, and both sides of the resin film were sandwiched between a copper foil having a thickness of 35 μm and a copper plate having a thickness of 1 mm, and vacuum pressed under conditions of a temperature of 200 ° C. and a pressure of 3 MPa to produce a laminate. The copper foil in the obtained laminate was etched to pattern the copper foil into a circle having a diameter of 2 cm to obtain a test sample. Using the obtained test sample, a thermal shock test was performed using a bath-type thermal shock tester (ESPEC's "TSB-51"), in which the test sample was held at -40 ° C. for 5 minutes, then heated to 120 ° C., held at 120 ° C. for 5 minutes, and then cooled to -40 ° C., forming one cycle. After 1000 cycles and 2000 cycles, the test samples were taken out. The presence or absence of cracks or cracks in the cured resin film was observed using an optical microscope (Olympus's "STM6").

[Thermal shock test criteria]
◯: No cracks or breaks in the cured product after 2000 cycles Δ: No cracks or breaks in the cured product after 1000 cycles, and some cracks or breaks in the cured product after 2000 cycles ×: Some cracks or breaks in the cured product after 1000 cycles

The compositions and results are shown in Tables 1 to 3 below.

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

Claims (18)

Contains an epoxy compound, an inorganic filler, and a curing agent;
The curing agent contains an active ester compound having a structure represented by the following formula (1):
The curing agent includes an active ester compound having no side chain,
A resin material (excluding resin materials used by impregnating a fiber substrate) in which the content of the inorganic filler is 55% by weight or more based on 100% by weight of the components excluding the solvent in the resin material.

In the formula (1), R1 and R2 each represent an organic group; X1 represents a group having an aromatic skeleton, and the group having an aromatic skeleton is an organic group having no reactive group; X2 represents a group containing an aliphatic chain skeleton, a group containing an aliphatic skeleton, or a group containing an aromatic skeleton; m represents an integer of 1 or more and 6 or less; and n represents an integer of 1 or more and 5 or less. Contains an epoxy compound, an inorganic filler, and a curing agent;
The curing agent contains an active ester compound having a structure represented by the following formula (1):
The curing agent includes a carbodiimide compound,
A resin material (excluding resin materials used by impregnating a fiber substrate) in which the content of the inorganic filler is 55% by weight or more based on 100% by weight of the components excluding the solvent in the resin material.

In the formula (1), R1 and R2 each represent an organic group; X1 represents a group having an aromatic skeleton, and the group having an aromatic skeleton is an organic group having no reactive group; X2 represents a group containing an aliphatic chain skeleton, a group containing an aliphatic skeleton, or a group containing an aromatic skeleton; m represents an integer of 1 or more and 6 or less; and n represents an integer of 1 or more and 5 or less. The resin material according to claim 1 or 2 , wherein in the formula (1), X1 is a group having two or more aromatic skeletons. The resin material according to any one of claims 1 to 3 , wherein in the formula (1), R1 or R2 is a group having a heteroaromatic ring skeleton. The resin material according to any one of claims 1 to 4 , wherein in the formula (1), R1 or R2 is a group having an imide skeleton. The resin material according to any one of claims 1 to 5 , wherein in the formula (1), R1 or R2 is a group having a naphthalene skeleton. The resin material according to any one of claims 1 to 6 , wherein in the formula (1), R1, R2, X1 and X2 are each a group not having a phosphorus atom. The resin material according to any one of claims 1 to 7 , wherein in the formula (1), R1, R2, X1 and X2 are each a group having 2 to 4 carbon atoms and not having an aliphatic hydrocarbon chain. The resin material according to any one of claims 1 to 8 , having a melt viscosity at 100°C of 5 Pa·s or more and 500 Pa·s or less. The resin material according to any one of claims 1 to 9 , wherein the active ester equivalent of the active ester compound having the structure represented by formula (1) is 200 eq/g or more and 500 eq/g or less. The resin material according to any one of claims 1 to 10 , wherein the epoxy compound comprises a naphthol aralkyl type epoxy compound. The resin material according to any one of claims 1 to 11 , wherein the inorganic filler is silica. The resin material according to any one of claims 1 to 12 , further comprising a curing accelerator. The resin material according to any one of claims 1 to 13 , comprising a bismaleimide compound. The resin material according to any one of claims 1 to 14 , comprising a thermoplastic resin. The resin material according to any one of claims 1 to 15 , which is a resin film. The resin material according to any one of claims 1 to 16 , which is used to form an insulating layer in a multilayer printed wiring board. 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 17 .

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