Resin compositions, prepregs, resin-containing films, resin-containing metal foils, metal-coated laminates, and printed circuit boards.

Abstract

The problem this disclosure aims to solve is to provide a resin composition whose cured product has a high glass transition temperature and good stain resistance, wherein the solder resist formed on a printed circuit board containing the cured product has good small-diameter opening properties. The resin composition contains a thermosetting resin (A), a coumarin compound (B), and an inorganic filler (C). The thermosetting resin (A) comprises an epoxy resin (A1) and a maleimide resin (A2). The content of maleimide resin (A2) is from 8% by mass to 60% by mass relative to the total amount of the thermosetting resin (A).

Description

Technical Field

[0001] This disclosure generally relates to resin compositions, prepregs, resin-containing films, resin-containing metal foil sheets, metal-coated laminates, and printed circuit boards. More specifically, this disclosure relates to resin compositions containing epoxy resin, prepregs, resin-containing films, resin-containing metal foil sheets, metal-coated laminates, and printed circuit boards. Background Technology

[0002] Printed circuit boards (PCBs) are widely used in various fields, including electronic devices, communication equipment, and computers. Recently, smaller devices such as storage devices, mobile communication devices, and notebook personal computers (PCs) have seen significant and rapid improvements in functionality, performance, and thickness and size. To keep pace with these trends, there is a growing demand for PCBs used in these products, such as further reductions in the feature size and density of their conductor lines, implementation of conductor lines in multiple layers with reduced thickness, and further improvements in their mechanical properties.

[0003] Patent Document 1 discloses a resin composition as a material for such a printed circuit board. The resin composition comprises: an epoxy compound, a maleimide compound having an N-phenylmaleimide structure, a phenolic compound, a core-shell rubber, and an inorganic filler. The content of the maleimide compound is equal to or greater than 10 parts by mass and less than 40 parts by mass relative to a total of 100 parts by mass of the epoxy compound, maleimide compound, and phenolic compound.

[0004] The cured product of the resin composition disclosed in Patent Document 1 has a high glass transition temperature and good desmear resistance, but it tends to reflect light in the range of 365 nm to 405 nm, which is the main wavelength range commonly used in metal halide lamps and UV LED light sources for curing UV-curable resins. In other words, light in this wavelength range tends to be reflected and scattered from the surface of the cured product. Therefore, in the solder resist (solder resist layer) formed on a printed circuit board including an insulating layer containing this cured product, light in this wavelength range is reflected and scattered from the surface of the insulating layer, thereby causing a reaction in undesirable portions of the solder resist. In other words, this reaction of the solder resist caused by the exposure process using light in this wavelength range is uncontrollable. Therefore, when using light in this wavelength range to expose and develop the solder resist formed on a printed circuit board made using this resin composition to create holes, the smaller the inner diameter of the hole, the more significantly the shape of the hole may be deformed. That is, such small-diameter holes cannot always be created in the desired shape, which is a problem faced by the resin composition of Patent Document 1.

[0005] Citation List

[0006] Patent documents

[0007] Patent Document 1: WO 2020 / 121734 A1 Summary of the Invention

[0008] One object of this disclosure is to provide a resin composition whose cured product has a high glass transition temperature and good stain resistance, and the resin composition ensures good small-diameter opening properties of solder resist formed on a printed circuit board containing the cured product, and also provides a prepreg, a resin-containing film, a resin-containing metal foil sheet, a metal-coated laminate, and a printed circuit board.

[0009] According to one aspect of this disclosure, a resin composition comprises a thermosetting resin (A), a coumarin compound (B), and an inorganic filler (C). The thermosetting resin (A) comprises an epoxy resin (A1) and a maleimide resin (A2). The content of the maleimide resin (A2) relative to the total mass of the thermosetting resin (A) is equal to or greater than 8% by mass and equal to or less than 60% by mass.

[0010] The prepreg according to another aspect of this disclosure includes at least one of the above-described resin composition or a semi-cured product of the resin composition; and a fibrous base member.

[0011] A resin-containing film according to another aspect of the present disclosure comprises: a resin layer comprising at least one of the above-described resin composition or a semi-cured product of the resin composition; and a support film.

[0012] According to another aspect of this disclosure, a resin-containing metal foil sheet comprises: a resin layer comprising at least one of the above-described resin composition or a semi-cured product of the resin composition; and a metal foil sheet.

[0013] According to another aspect of this disclosure, the metal-clad laminate comprises: an insulating layer comprising a cured product of the above-described resin composition; and a metal layer.

[0014] According to another aspect of this disclosure, the metal-clad laminate includes: an insulating layer comprising a cured product of the prepreg described above; and a metal layer.

[0015] A printed circuit board according to another aspect of this disclosure includes: an insulating layer comprising a cured product of the above-described resin composition; and conductor lines.

[0016] A printed circuit board according to another aspect of this disclosure includes: an insulating layer comprising a cured product of the prepreg described above; and conductor lines. Attached Figure Description

[0017] [ Figure 1 ] Figure 1 This is a schematic cross-sectional view showing a prepreg according to one embodiment of the present disclosure;

[0018] [ Figure 2 ] Figure 2 This is a schematic cross-sectional view showing a resin-containing film (without a cover film) according to one embodiment of the present disclosure;

[0019] [ Figure 3 ] Figure 3 This is a schematic cross-sectional view showing a resin-containing film (and a covering film) according to an embodiment of the present disclosure;

[0020] [ Figure 4 ] Figure 4 This is a schematic cross-sectional view showing a metal foil sheet having a resin according to one embodiment of the present disclosure;

[0021] [ Figure 5 ] Figure 5 This is a schematic cross-sectional view showing a metal-clad laminate according to one embodiment of the present disclosure;

[0022] [ Figure 6 ] Figure 6This is a schematic cross-sectional view showing a printed circuit board according to one embodiment of the present disclosure;

[0023] [ Figure 7 ] Figure 7 This is a schematic diagram illustrating a grade S or grade A as an exemplary evaluation result of small diameter opening performance in one embodiment of this disclosure;

[0024] [ Figure 8 ] Figure 8 This is a schematic diagram illustrating grade B as another exemplary evaluation result of small-diameter aperture performance in one embodiment of this disclosure; and

[0025] [ Figure 9 ] Figure 9 This is a schematic diagram illustrating grade B as another exemplary evaluation result of small-diameter opening performance in one embodiment of this disclosure. Detailed Implementation

[0026] 1. Summary

[0027] According to one embodiment, the resin composition comprises a thermosetting resin (A), a coumarin compound (B), and an inorganic filler (C). The thermosetting resin (A) comprises an epoxy resin (A1) and a maleimide resin (A2). The content of maleimide resin (A2) relative to the total mass of the thermosetting resin (A) is equal to or greater than 8% by mass and equal to or less than 60% by mass.

[0028] As described above, when the resin composition contains these components, the glass transition temperature (Tg) of the cured product of the resin composition is increased.

[0029] Furthermore, when the resin composition contains these components, the stain resistance of the cured product of the resin composition is improved. Improved stain resistance of the cured product of the resin composition reduces the likelihood of deformation of the processed parts, peeling of metal foil sheets, and other inconveniences that could occur in the printed circuit board 5 manufactured using the resin composition. This can reduce the drastic decline in the conductor reliability of the printed circuit board 5 manufactured using the resin composition.

[0030] Furthermore, when the resin composition contains these components, the small-diameter openings of the solder resist (SR) 8 to be formed on the printed circuit board 5 manufactured using the resin composition can be improved (see [link]). Figure 7In other words, this allows the cured product of the resin composition to have a reflectivity of less than or equal to 20% for light with wavelengths equal to or greater than 365 nm and equal to or less than 405 nm, thereby ensuring good small-diameter aperture properties of the solder resist 8 to be formed on the printed circuit board 5 manufactured using the resin composition. Specifically, firstly, solder resist 8 is formed on the printed circuit board 5 manufactured using the resin composition. Next, the solder resist 8 thus formed is exposed to exposure radiation with wavelengths equal to or greater than 365 nm and equal to or less than 405 nm through a photomask, thereby causing the desired portions of the solder resist 8 to react. At this time, the insulating layer 50 of the printed circuit board 5 manufactured using the resin composition can reduce the reflection and scattering of the exposure radiation that has reached the surface of the insulating layer 50 in this wavelength range. This can prevent or at least reduce the reaction of undesired portions of the solder resist 8 formed on the printed circuit board 5. Afterwards, the solder resist 8 can be patterned into the desired shape using a developer. That is to say, ensuring good small-diameter aperture properties of the solder resist 8 means that the solder resist 8 can be removed more finely and accurately. In other words, using this resin composition to manufacture the printed circuit board 5 helps to further reduce the feature size and increase the density of the conductor lines 51 on the printed circuit board 5.

[0031] A solder resist with a known composition can be used as solder resist 8. For example, solder resist 8 may contain epoxy resin, polyimide resin, polyphenylene ether resin, or aromatic polyolefin resin. Note that if the portion of the solder resist exposed to radiation reacts but does not dissolve in the developer, then the solder resist is a negative solder resist. If the portion of the solder resist exposed to radiation reacts and dissolves in the developer, then the solder resist is a positive solder resist.

[0032] As used herein, "small diameter aperture" means that the aperture 7 created by exposing the solder resist 8 to exposure radiation within the specified wavelength range and developing the solder resist 8 has the desired shape. Additionally, as used herein, "small diameter" refers to an approximately circular aperture with a diameter equal to or less than 100 μm.

[0033] In other words, this embodiment allows for the provision of a resin composition whose cured product has a high glass transition temperature and good stain resistance, and the resin composition ensures good small-diameter opening properties for the solder resist 8 to be formed on the printed circuit board 5 manufactured using the resin composition. It also allows for the provision of a prepreg 1, a resin-containing film 2, a resin-containing metal foil sheet 3, a metal-coated laminate 4, and the printed circuit board 5. Using at least one of the resin composition, prepreg 1, resin-containing film 2, resin-containing metal foil sheet 3, or metal-coated laminate 4 to manufacture the printed circuit board 5 will effectively contribute to reducing the feature size and increasing the density of the conductor lines 51 on the surface of the printed circuit board 5.

[0034] 2. Details

[0035] (1) Resin composition

[0036] The resin composition according to this embodiment is used, for example, as a material for prepreg 1, a material for a resin-containing film 2, a material for a resin-containing metal foil sheet 3, a material for a metal-coated laminate 4, and a material for a printed circuit board 5.

[0037] The resin composition contains a thermosetting resin (A), a coumarin compound (B), and an inorganic filler (C). This enables the resin composition to be thermosetting. The thermosetting resin (A) comprises an epoxy resin (A1) and a maleimide resin (A2).

[0038] The cured product of the resin composition has a glass transition temperature equal to or higher than 200°C. In this case, the cured product of the resin composition has a high glass transition temperature and can exhibit excellent heat resistance. The glass transition temperature is preferably equal to or higher than 210°C, and more preferably equal to or higher than 220°C. An upper limit for the glass transition temperature may be, for example, 400°C, but this should not be construed as a limiting provision.

[0039] For example, a resin composition can be prepared as follows: Specifically, a thermosetting resin (A) comprising an epoxy resin (A1) and a maleimide resin (A2), a coumarin compound (B), and an inorganic filler (C) are mixed together. The resulting mixture is diluted with a suitable solvent. The diluted mixture is then stirred, mixed, and homogenized.

[0040] The constituent components of the resin composition will be described next. Note that, as used herein, “parts by mass” and “% by mass” refer only to the mass of the constituent component and do not include the mass of the solvent.

[0041] (1.1) Components of the resin composition

[0042] <Thermosetting Resin (A)>

[0043] As described above, the resin composition contains a thermosetting resin (A). The thermosetting resin (A) comprises a thermosetting compound. When heated, the thermosetting compound undergoes a polymerization reaction, causing its molecular chains to crosslink, thereby forming a three-dimensional polymer network structure. As a result, the thermosetting compound is cured.

[0044] The thermosetting resin (A) comprises an epoxy resin (A1) and a maleimide resin (A2). Optionally, the thermosetting resin (A) may also comprise thermosetting compounds other than epoxy resin (A1) and maleimide resin (A2). Specifically, such thermosetting compounds may be, for example, phenolic resin (A3). The thermosetting resin (A) may also comprise other thermosetting compounds besides epoxy resin (A1), maleimide resin (A2), and phenolic resin (A3). Examples of such other thermosetting compounds include, but are not limited to, benzoxazine resins, polyphenylene ether resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, silicone resins, polyurethane resins, polyimide resins, acrylic resins, and methacrylic resins. The resin composition may contain only one type of thermosetting resin (A), or it may contain two or more types of thermosetting resin (A), either way being suitable.

[0045] <<Epoxy Resin (A1)>>

[0046] As described above, the thermosetting resin (A) includes epoxy resin (A1). Epoxy resin (A1) is a component that can increase the glass transition temperature of the cured product of the resin composition, as well as improve its adhesion to materials such as metals and glass, heat resistance, electrical insulation, and flame retardancy.

[0047] Epoxy resin (Al) is a compound having one or more epoxy groups in its molecule. Epoxy resin (Al) can be in a solid or liquid phase at 25°C, either of which is suitable.

[0048] Examples of epoxy resins (A1) include, but are not limited to, bisphenol epoxy resins, phenolic varnish epoxy resins, biphenyl epoxy resins, xylene epoxy resins, aryl-alkylene epoxy resins, naphthalene epoxy resins, naphthalene skeleton-modified epoxy resins, triphenylmethane epoxy resins, anthracene epoxy resins, dicyclopentadiene epoxy resins, norbornene epoxy resins, fluorene epoxy resins, stilbene epoxy resins, and phosphorus-containing epoxy resins obtained by introducing phosphorus atoms into these epoxy resins. Thermosetting resins (A) may contain only one type of epoxy resin (A1), or may contain two or more types of epoxy resins (A1), either case is suitable.

[0049] Examples of bisphenol epoxy resins include, but are not limited to, bisphenol A epoxy resin, bisphenol F epoxy resin and bisphenol S epoxy resin.

[0050] Examples of phenolic varnish epoxy resins include, but are not limited to, phenol-phenolic varnish epoxy resins and cresol-phenolic varnish epoxy resins.

[0051] Examples of aryl-alkylene epoxy resins include, but are not limited to, phenol-arylene epoxy resins, biphenyl-arylene epoxy resins, biphenyl-phenolic varnish epoxy resins, biphenyl-dimethylene epoxy resins, triphenol-methane-phenolic varnish epoxy resins, and tetramethylbiphenyl epoxy resins.

[0052] Examples of naphthalene skeleton-modified epoxy resins include, but are not limited to, naphthalene skeleton-modified cresol-phenolic varnish epoxy resin, naphthol-arylalkyl epoxy resin, naphthol-arylalkyl epoxy resin, methoxy-naphthalene-modified cresol-phenolic varnish epoxy resin, and methoxy-naphthalene-dimethylene epoxy resin.

[0053] Note that epoxy resins (A1) are not always classified into only one type of resin. For example, biphenyl-aralkyl epoxy resins are classified not only as aryl-alkylene epoxy resins but also as biphenyl epoxy resins.

[0054] The epoxy resin (A1) preferably comprises at least one epoxy resin selected from the group consisting of biphenyl epoxy resin, naphthalene epoxy resin, and dicyclopentadiene epoxy resin. In this case, the glass transition temperature, heat resistance, and flame retardancy of the cured product of the resin composition can be improved. Furthermore, the biphenyl epoxy resin more preferably comprises at least one of biphenyl-phenolic varnish epoxy resin or biphenyl-aralkyl epoxy resin.

[0055] The content of epoxy resin (A1) relative to the total mass of thermosetting resin (A) is preferably equal to or greater than 10% by mass, more preferably equal to or greater than 20% by mass, and even more preferably equal to or greater than 25% by mass. This can improve the glass transition temperature of the cured product of the resin composition, as well as its adhesion to materials such as metals and glass, heat resistance, flame retardancy, and electrical insulation. On the other hand, the content of epoxy resin (A1) relative to the total mass of thermosetting resin (A) is preferably equal to or less than 70% by mass, more preferably equal to or less than 60% by mass, and even more preferably equal to or less than 50% by mass. This can reduce the abrupt decrease in adhesion to materials such as metals and glass and electrical insulation.

[0056] The epoxy equivalent of the epoxy resin (A1) is preferably equal to or greater than 100 g / eq., and more preferably equal to or greater than 150 g / eq. On the other hand, the epoxy equivalent of the epoxy resin (A1) is preferably equal to or less than 350 g / eq., and more preferably equal to or less than 300 g / eq.

[0057] <<Maleimide Resin (A2)>>

[0058] As described above, the thermosetting resin (A) includes maleimide resin (A2). Maleimide resin (A2) is a component that can increase or improve the glass transition temperature, heat resistance, and stain resistance of the cured product of the resin composition.

[0059] Maleimide resin (A2) is a compound that can react with epoxy resin (A1). Maleimide resin (A2) has one or more maleimide groups in one molecule. Maleimide resin (A2) can be in the solid or liquid phase at 25°C, either condition is suitable.

[0060] Maleimide resin (A2) may contain only one type of compound or may contain two or more types of compounds, either way is suitable. Examples of maleimide resin (A2) include, but are not limited to: monofunctional maleimide resins each having one maleimide group in one molecule and polyfunctional maleimide resins each having two or more maleimide groups in one molecule. Thermosetting resin (A) may contain only one type of maleimide resin (A2) or may contain two or more types of maleimide resin (A2), either way is suitable.

[0061] Examples of monofunctional maleimide resins having one maleimide group per molecule include, but are not limited to: chlorophenyl maleimide (e.g., o-chlorophenyl maleimide), methylphenyl maleimide (e.g., o-methylphenyl maleimide), hydroxyphenyl maleimide (e.g., p-hydroxyphenyl maleimide), carboxyphenyl maleimide (e.g., p-carboxyphenyl maleimide), N-dodecyl maleimide, and phenylmethane maleimide.

[0062] Examples of polyfunctional maleimide resins having two or more maleimide groups per molecule include, but are not limited to: 4,4'-diphenylmethane bismaleimide, bisphenol A bis(4-maleimide phenyl ether), 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6-bismaleimide-(2,2,4-trimethyl)hexane, 4,4'-diphenyl ether bismaleimide, 4,4'-diphenyl sulfone bismaleimide, 1,3-bis(3-maleimide phenoxy)benzene, 1,3-bis(4-maleimide phenoxy)benzene, polyphenylmethane maleimide, and polyphenylmethane maleimide.

[0063] The maleimide resin (A2) preferably contains at least polyphenylmethane maleimide. This allows for an increase in the glass transition temperature and heat resistance of the cured product of the resin composition.

[0064] The content of maleimide resin (A2) relative to the total mass of thermosetting resin (A) is equal to or greater than 8% by mass, preferably equal to or greater than 15% by mass, and more preferably equal to or greater than 25% by mass. This allows for an increase in the glass transition temperature of the cured product of the resin composition. On the other hand, the content of maleimide resin (A2) relative to the total mass of thermosetting resin (A) is equal to or less than 60% by mass, preferably equal to or less than 55% by mass, and more preferably equal to or less than 45% by mass. This can reduce the drastic decrease in the stain resistance of the cured product of the resin composition.

[0065] The mass ratio of epoxy resin (A1) to maleimide resin (A2) is preferably 10:1 to 2:5, more preferably 5:1 to 1:2, and even more preferably 3:2 to 2:3. This allows for an increase in the glass transition temperature and heat resistance of the cured product of the resin composition, and reduces the abrupt decrease in stain resistance.

[0066] <<Phenolic Resin (A3)>>

[0067] Thermosetting resin (A) may include phenolic resin (A3). Phenolic resin (A3) is a component that can improve the glass transition temperature, heat resistance, and other properties of the cured product of the resin composition.

[0068] Phenolic resin (A3) can react with epoxy resin (A1) and maleimide resin (A2). Phenolic resin (A3) contains a phenolic hydroxyl group in one molecule. Phenolic resin (A3) can be in either a solid or liquid phase at 25°C, whichever is more suitable.

[0069] Examples of phenolic resins (A3) include, but are not limited to: biphenyl-aralkylphenolic resins, phenyl-aralkylphenolic resins, phenolic varnish resins, cresol-phenolic varnish resins, bisphenol A phenolic varnish resins, naphthol resins, tetraphenol resins, and phosphorus-containing phenolic resins in which phosphorus atoms are introduced into these phenolic resins. Thermosetting resins (A) may contain only one type of phenolic resin (A3), or may contain two or more types of phenolic resins (A3), either case is suitable.

[0070] The phenolic resin (A3) preferably includes at least one of naphthol-formaldehyde resin or biphenyl-formaldehyde resin. This allows for an increase in the glass transition temperature and heat resistance of the cured product of the resin composition.

[0071] The content of phenolic resin (A3) relative to the total mass of thermosetting resin (A) is preferably equal to or greater than 10% by mass, more preferably equal to or greater than 15% by mass, and even more preferably equal to or greater than 20% by mass. This allows for an increase in the glass transition temperature and heat resistance of the cured product of the resin composition. On the other hand, the content of phenolic resin (A3) relative to the total mass of thermosetting resin (A) is preferably equal to or less than 65% by mass, more preferably equal to or less than 55% by mass, and even more preferably equal to or less than 45% by mass. This can reduce the abrupt decrease in the brittleness of the cured product of the resin composition.

[0072] The phenolic hydroxyl equivalent of the phenolic resin (A3) is preferably equal to or greater than 100 g / eq., and more preferably equal to or greater than 120 g / eq. On the other hand, the phenolic hydroxyl equivalent of the phenolic resin (A3) is preferably equal to or less than 650 g / eq., and more preferably equal to or less than 600 g / eq.

[0073] If the thermosetting resin (A) contains phenolic resin (A3), the mass ratio of epoxy resin (A1) to phenolic resin (A3) is preferably 5:1 to 1:2, and more preferably 5:2 to 2:3. This allows for an increase in the glass transition temperature and heat resistance of the cured product of the resin composition.

[0074] <Coumarin compound (B)>

[0075] As described above, the resin composition contains a coumarin compound (B). The coumarin compound (B) has a coumarin skeleton. The coumarin skeleton is an aromatic compound in which a lactone ring and an aromatic ring are fused. The coumarin compound (B) exhibits good absorbance to exposure radiation within the specified wavelength range above, thus reducing the reflectance of the cured product of the resin composition to light with wavelengths equal to or greater than 365 nm and equal to or less than 405 nm.

[0076] The coumarin compound (B) preferably comprises a coumarin compound (B1) represented by at least one of the following formulas (1) and (2):

[0077] [Chemical Formula 1]

[0078]

[0079] [Chemical Formula 2]

[0080]

[0081] In formulas (1) and (2), R1 and R2 each independently represent a hydrogen atom, an alkyl group, an aryl group, or a hydroxyalkyl group. R3, R4, and R5 each independently represent a hydrogen atom, an alkyl group, or an aryl group. The number of carbon atoms in the alkyl and hydroxyalkyl groups is not limited to any specific value. The alkyl and hydroxyalkyl groups can be straight-chain or branched, either is acceptable, and can have, but are not limited to, eight or fewer carbon atoms. R1 to R5 can be bonded to other substituents to form a ring structure.

[0082] Examples of coumarin compounds (B1) include, but are not limited to, coumarin, 4-methylcoumarin, and 7-amino-4-methylcoumarin. The resin composition may contain only one type of coumarin compound (B1), or it may contain two or more types of coumarin compounds (B1), either way being suitable.

[0083] The absorbance and absorption wavelength of coumarin compound (B) can be altered by introducing substituents. For example, introducing an electron-donating group at the 7-position of coumarin compound (B) allows the electron-donating and electron-withdrawing groups to coexist within the molecule, resulting in intramolecular charge transfer. Consequently, coumarin compound (B) can exhibit greater absorbance.

[0084] The absorbance of coumarin compound (B) depends on the number of molecules. Therefore, the larger the number of molecules (i.e., the greater the molar number of molecules), the greater the absorbance of coumarin compound (B).

[0085] Relative to the total mass of the thermosetting resin (A) and the coumarin compound (B), the content of coumarin compound (B) is preferably equal to or greater than 0.1% by mass, more preferably equal to or greater than 1.5% by mass, and even more preferably equal to or greater than 2.0% by mass. This can reduce the reflectance of the cured product of the resin composition for wavelengths equal to or greater than 365 nm and equal to or less than 405 nm. On the other hand, relative to the total mass of the thermosetting resin (A) and the coumarin compound (B), the content of coumarin compound (B) is preferably equal to or less than 10% by mass, more preferably equal to or less than 9% by mass, and even more preferably equal to or less than 8% by mass. This can reduce the abrupt decrease in the glass transition temperature of the cured product of the resin composition.

[0086] <Inorganic filler (C)>

[0087] As described above, the resin composition contains an inorganic filler (C). The inorganic filler (C) can reduce the coefficient of thermal expansion of the cured product of the resin composition.

[0088] Examples of inorganic fillers (C) include, but are not limited to, fillers containing silica (such as fused silica and crystalline silica), talc, boehmite, magnesium hydroxide, aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, clay, and mica. The resin composition may contain only one type of inorganic filler (C), or it may contain two or more types of inorganic fillers (C), either way being suitable.

[0089] The inorganic filler (C) preferably comprises at least one filler selected from the group consisting of: silica, talc, boehmite, magnesium hydroxide, and aluminum hydroxide. This can reduce the coefficient of thermal expansion of the cured product of the resin composition.

[0090] Inorganic fillers (C) can be surface-treated to improve, for example, their affinity for thermosetting resins (A) and to prevent aggregation. Specific types of surface treatments include, but are not limited to, animosyl-silane treatment, mercapto-silane treatment, and alkoxy-silane treatment.

[0091] The average particle size (D50) of the inorganic filler (C) is preferably equal to or greater than 0.1 μm. On the other hand, the average particle size of the inorganic filler (C) is preferably equal to or less than 10 μm. As used herein, "average particle size" refers to the particle size at the 50% cumulative value in the volumetric particle size distribution measured by laser diffraction scattering.

[0092] The content of inorganic filler (C) is preferably equal to or greater than 50 parts by mass relative to a total of 100 parts by mass of thermosetting resin (A) and coumarin compound (B), and more preferably equal to or greater than 75 parts by mass. This can reduce the coefficient of thermal expansion of the cured product of the resin composition. On the other hand, the content of inorganic filler (C) is preferably equal to or less than 300 parts by mass relative to a total of 100 parts by mass of thermosetting resin (A) and coumarin compound (B), and more preferably equal to or less than 250 parts by mass. This can reduce the drastic decrease in adhesion and crack resistance of the cured product of the resin composition.

[0093] <Amine Compound (D)>

[0094] The resin composition may contain an amine compound (D) that does not have a coumarin backbone. Therefore, the amine compound (D) is a different compound from the coumarin compound (B1) represented by formula (2). The amine compound (D) is used as a curing agent or curing accelerator for the crosslinking (curing) reaction of the thermosetting resin (A) and plays an auxiliary role in the crosslinking reaction.

[0095] Examples of amine compounds (D) include aromatic amine compounds and fatty acid amine compounds.

[0096] Examples of aromatic amine compounds include, but are not limited to, imidazole compounds, such as 2-methylimidazole and 2-ethyl-4-methylimidazole. Aromatic amine compounds preferably comprise imidazole compounds.

[0097] Examples of aliphatic amine compounds include, but are not limited to, dicyandiamide (DICY), alicyclic compounds such as diazabicycloundecene (DBU) and isophorone diamine (IPDA), and chain aliphatic amine compounds such as diethylenetriamine (DTA) and triethylenetetramine (TTA). Aliphatic amine compounds preferably include dicyandiamide.

[0098] The resin composition may contain only one type of amine compound (D), or it may contain two or more types of amine compounds (D), either way is suitable.

[0099] The content of amine compound (D) relative to a total of 100 parts by mass of thermosetting resin (A) and coumarin compound (B) is preferably equal to or greater than 0.005 parts by mass, more preferably equal to or greater than 0.01 parts by mass, and even more preferably equal to or greater than 0.05 parts by mass. On the other hand, the content of amine compound (D) relative to a total of 100 parts by mass of thermosetting resin (A) and coumarin compound (B) is preferably equal to or less than 10 parts by mass, more preferably equal to or less than 8 parts by mass, and even more preferably equal to or less than 7 parts by mass.

[0100] Core-shell rubber (E)

[0101] The resin composition may contain core-shell rubber (E). Core-shell rubber (E) can improve properties such as glass transition temperature, heat resistance, flame retardancy, and impact resistance, and can reduce the drastic decline in properties such as coefficient of thermal expansion and stain resistance. Core-shell rubber (E) consists of a filler-like rubber core and a shell that serves as a graft layer and covers the core.

[0102] The core preferably comprises at least one selected from the group consisting of: polymers of (meth)acrylic acid, polymers of (meth)acrylates, polymers of olefin compounds, polybutadiene, and silicone resins. The shell preferably comprises at least one selected from the group consisting of: styrene-acrylonitrile copolymers, polymers of (meth)acrylic acid, polybutadiene, and silicone resins. An example of such a core-shell rubber (E) can be a silicone resin-acrylic composite rubber. In a silicone resin-acrylic composite rubber, the core is a silicone resin / acrylic polymer, and the shell is a styrene-acrylonitrile copolymer. As used herein, "(meth)acrylic acid" means at least one of acrylic acid or methacrylic acid. The resin composition may contain only one type of core-shell rubber (E), or it may contain two or more types of core-shell rubber (E), either case is suitable.

[0103] Commercially available products can be used as core-shell rubber (E). Examples of such commercially available products include, but are not limited to: products named “S-2001,” “S-2006,” “S-2501,” “S-2030,” “S-2100,” “S-2130,” “S-2200,” “SRK200A,” “SX-006,” and “SX-005” (manufactured by Mitsubishi Chemical Corporation); products named “AC3816,” “AC3816N,” “AC3832,” “AC4030,” “AC3364,” and “IM101” (manufactured by Aica Kogyo Co., Ltd.); and products named “MX-153,” “MX-257,” “MX-154,” “MR-960,” “MX-136,” “MX-965,” “MX-217,” and “MR-01” (manufactured by Kaneka). Products manufactured by Dow Chemical Company Japan (manufactured by Dow Chemical Company Japan); products named “EXL-2655”, “TMS-2670J” and “TMS-2670S”; and products named “R-170S”, “R-180S” and “R-200” (manufactured by Nisshin Chemical Co., Ltd.).

[0104] The average particle size of the core-shell rubber (E) is, for example, equal to or greater than 0.001 μm and equal to or less than 1 μm. The average particle size is preferably equal to or less than 0.5 μm.

[0105] The content of core-shell rubber (E) relative to the total mass of the resin components in the resin composition is preferably equal to or greater than 10% by mass, and more preferably equal to or greater than 17.5% by mass. On the other hand, the content of core-shell rubber (E) relative to the total mass of the resin components in the resin composition is preferably equal to or less than 50% by mass, and more preferably equal to or less than 40% by mass. As used herein, "resin component" refers to the non-volatile components in the resin composition other than the inorganic filler (C).

[0106] <Additives>

[0107] The composition and content of the additives are not limited to any specific composition and content, as long as they do not impair the advantages of this embodiment.

[0108] Examples of additives include, but are not limited to, curing agents and curing accelerators other than amine compounds (D), thermoplastic resins, flame retardants, colorants, coupling agents, heat stabilizers, antioxidants, reaction initiators, defoamers, antistatic agents, dyes, pigments, polymerization inhibitors, and lubricants.

[0109] Examples of curing agents and curing accelerators other than amine compounds (D) include acid anhydrides, isocyanate compounds, triphenylphosphine, thiols, and metal salts of organic acids, such as metal soaps.

[0110] (1.2) Method for preparing resin compositions

[0111] A method for preparing a resin composition may include, but is not limited to, the following steps: mixing an epoxy resin (A1) and a maleimide resin (A2) as thermosetting resins (A), a coumarin compound (B), and an inorganic filler (C) such that these components have their respective predetermined amounts. If desired, phenolic resin (A3), an amine compound (D), a core-shell rubber (E), and additives may be added to the mixture, and the resulting mixture may be compounded.

[0112] Optionally, the resin composition may also contain an organic solvent. That is, the resin composition is preferably used as a varnish-like resin composition containing an organic solvent. Note that the varnish-like resin composition not only has the components of the resin composition described above, but also has an organic solvent as an additional component.

[0113] Such a varnish-form resin composition can be prepared as follows: First, the components of the resin composition that are soluble in an organic solvent are introduced into the organic solvent, and stirred and mixed to prepare a mixture. Optionally, the mixture can also be prepared by stirring and mixing while heating. Subsequently, other components that are insoluble in the organic solvent are introduced into the mixture, and continuously dispersed using, for example, a ball mill, bead mill, or planetary mixer, until the mixture has a predetermined dispersion state, thereby preparing a varnish-form resin composition. Note that the organic solvent used in this case is not limited to any specific organic solvent, but preferably is an organic solvent that can dissolve the thermosetting resin (A), the coumarin compound (B), and other components without inhibiting the curing reaction of the resin composition. Examples of organic solvents include, but are not limited to, toluene and methyl ethyl ketone (MEK).

[0114] (2) Exemplary applications of resin compositions

[0115] Now refer to Figure 1-6 Exemplary applications of the resin composition are described.

[0116] Prepreg 1, resin-containing film 2, resin-containing metal foil sheet 3, metal-coated laminate 4, and printed circuit board 5 can be obtained using resin compositions.

[0117] More specifically, the resin layer 10 included in the prepreg 1 comprises at least one of a resin composition or a semi-cured product of a resin composition. The resin layer 20 included in the resin-containing film 2 comprises at least one of a resin composition or a semi-cured product of a resin composition. The resin layer 30 included in the resin-containing metal foil sheet 3 comprises at least one of a resin composition or a semi-cured product of a resin composition. The insulating layer 40 included in the metal-clad laminate 4 comprises a cured product of a resin composition. The insulating layer 50 included in the printed circuit board 5 comprises a cured product of a resin composition.

[0118] In this embodiment, the resin composition is in the initial stage, that is, the resin composition is an uncured product, soluble in a specific type of liquid, and fusible. In other words, the uncured product of the resin composition is in stage A.

[0119] As used herein, "semi-cured product" refers to a resin composition that has been cured but not fully cured, and whose degree of curing allows for further curing. For example, when the resin composition according to this embodiment is heated, its viscosity gradually decreases over a period of time from the start of heating. However, thereafter, the resin composition begins to cure, causing the viscosity to gradually increase. It can be seen that, as used herein, a semi-cured product refers to a resin composition in a semi-cured state, that is, a resin composition that has transitioned to the so-called "Stage B".

[0120] (2.1) Prepreg

[0121] Figure 1 A prepreg 1 according to this embodiment is shown. The prepreg 1 has an integral sheet or film shape. The prepreg 1 is used to manufacture the metal-clad laminate 4 and the printed circuit board 5. Specifically, the prepreg 1 is used as the material for the metal-clad laminate 4 and as the material for the printed circuit board 5, and is used to form a multilayer printed circuit board 5 (by stacking).

[0122] Prepreg 1 comprises at least one of a resin composition or a semi-cured product of a resin composition. Optionally, such as Figure 1 As shown, the prepreg 1 may include a resin layer 10. That is, the resin layer 10 includes at least one of a resin composition or a semi-cured product of a resin composition. The resin layer 10 also includes a fiber substrate 11. That is, the prepreg 1 may include a resin layer 10 formed by impregnating the fiber substrate 11 with at least one of a resin composition or a semi-cured product of a resin composition.

[0123] Furthermore, the prepreg 1 obtained by using the resin composition may contain a semi-cured product of the resin composition as described above or an uncured resin composition, i.e., an uncured product of the resin composition, either case is suitable.

[0124] As described above, the prepreg 1 may include a resin layer 10 formed by impregnating the fiber substrate 11 with at least one of the resin compositions or semi-cured products of the resin composition. When impregnating the fiber substrate 11 with at least one of the resin compositions or semi-cured products of the resin composition, a varnish prepared from the resin composition is preferably used.

[0125] In this implementation plan, such as Figure 1 As shown, prepreg 1 comprises a single fiber substrate 11. Alternatively, prepreg 1 may also comprise two or more fiber substrates 11.

[0126] The fiber substrate 11 is a reinforcing member. Examples of fiber substrate 11 include, but are not limited to, glass cloth, aramid cloth, polyester cloth, glass nonwoven fabric, aramid nonwoven fabric, polyester nonwoven fabric, pulp paper, and linter paper. In particular, the use of glass cloth allows for the provision of a laminate with excellent mechanical strength. Any type of glass can be used without limitation to form the glass cloth. Examples of glass include E glass, S glass, Q glass, T glass, TS glass, NE glass, and L glass. Regardless of the type of glass the glass cloth is made of, using glass cloth as the fiber substrate 11 of the prepreg enables the prepreg 1 to achieve the advantages of this disclosure. Preferably, the glass cloth is flattened. According to a specific example of flattening, the yarn can be compressed into a flat shape, for example, by continuously pressing the glass cloth with a pressure roller at appropriate pressure. Note that, for example, the thickness of the fiber substrate 11 commonly used can be, but is not limited to, equal to or greater than 10 μm and equal to or less than 180 μm. The glass cloth contains glass fibers. Alternatively, the glass cloth may also contain reinforcing fibers other than glass fibers. For example, before impregnating the glass cloth with a resin composition in the form of a varnish, a coupling agent can be used to surface-treat the glass cloth. Surface treatment of the glass cloth can improve the adhesion between the glass cloth and the resin composition. Examples of surface treatments include, but are not limited to, surface treatments applicable to the aforementioned inorganic filler (C).

[0127] For example, the thickness of prepreg 1 may be, but is not limited to, equal to or greater than 10 μm and equal to or less than 200 μm.

[0128] In addition, to form the resin layer 10, the fiber substrate 11 is impregnated with varnish, either by immersing the fiber substrate 11 in the varnish or by applying the varnish to the fiber substrate 11. If necessary, the fiber substrate 11 can be repeatedly impregnated with varnish multiple times. Furthermore, in this case, by repeatedly impregnating the fiber substrate 11 with various different types of varnish (having different chemical compositions and concentrations), a resin layer 10 containing a resin composition or a semi-cured product of a resin composition can eventually be obtained, which has the target composition and contains the desired amount of varnish.

[0129] Optionally, for example, a method of manufacturing prepreg 1 may include reducing the content of organic solvent in the resin layer 10 or removing organic solvent from the resin layer 10 by heating the resin layer 10 (which is manufactured by impregnating the fiber substrate 11 with a varnish comprising a resin composition and an organic solvent). Conditions for reducing the content of organic solvent in the resin layer 10 or removing organic solvent from the resin layer 10 by heating the resin layer 10 may include a temperature equal to or higher than 80°C and equal to or lower than 180°C, and a duration equal to or longer than 1 minute and equal to or shorter than 10 minutes.

[0130] Note that the method for manufacturing the prepreg 1 comprising at least one of the resin composition according to this embodiment or a semi-cured product of the resin composition and the fiber substrate 11 is not limited to the method described above. That is, the prepreg 1 manufactured using the resin composition according to this embodiment can be manufactured by any suitable method.

[0131] Note that as long as prepreg 1 is manufactured using general manufacturing methods, the surface roughness of its cured product will not affect the reflectivity. That is, the reflectivity of the cured product of prepreg 1 is not affected by surface roughness, but depends solely on the chemical composition of the resin composition. Therefore, the cured product of prepreg 1 manufactured using the above-described resin composition can reflect light with a wavelength equal to or greater than 365 nm and equal to or less than 405 nm with a reflectivity equal to or less than 20%, regardless of its surface roughness. The surface roughness of the cured product of prepreg 1 can be expressed, for example, by an arithmetic mean roughness Sa. For example, the arithmetic mean roughness Sa can be, but is not limited to, equal to or greater than 0.01 μm and equal to or less than 2 μm.

[0132] The prepreg 1 according to this embodiment is manufactured using the resin composition according to this embodiment. Therefore, the glass transition temperature of the cured product of the resin composition can be increased to a temperature equal to or higher than 200°C, ensuring good stain resistance of the cured product of the resin composition. The reflectivity of the cured product of the resin composition for light with wavelengths equal to or greater than 365 nm and equal to or less than 405 nm can be reduced to below 20%, and good small-diameter opening properties of the solder resist 8 to be formed on the printed circuit board 5 manufactured using the resin composition can be ensured. Note that the prepreg 1 according to this embodiment can be used not only for manufacturing the printed circuit board 5 but also for various other applications.

[0133] Note that prepreg 1 is a resin-impregnated substrate. As used herein, "resin-impregnated substrate" refers to a fibrous substrate impregnated with a resin composition or a semi-cured product of a resin composition. Examples of resin-impregnated substrates other than prepreg 1 include resin fabrics.

[0134] (2.2) Film containing resin

[0135] Figure 2 and 3 A resin-containing film 2 according to this embodiment is shown. The overall shape of the resin-containing film 2 is a film or sheet. For example, the resin-containing film 2 can be used to form a multilayer printed circuit board 5 (by stacking).

[0136] The resin-containing membrane 2 comprises: a resin layer 20 containing at least one of a resin composition or a semi-cured product of a resin composition, and a support membrane 21. That is, the resin-containing membrane 2 comprises: a resin layer 20 containing at least one of a resin composition or a semi-cured product of a resin composition, and a support membrane 21 stacked on the resin layer 20. Optionally, the resin-containing membrane 2 may further comprise other layers between the resin layer 20 and the support membrane 21.

[0137] Furthermore, as described above, the resin layer 20 may comprise a semi-cured product of the resin composition or an uncured product of the uncured resin composition. In other words, the resin-containing membrane 2 may be a resin-containing membrane 2 comprising: a resin layer 20 comprising a semi-cured product of the resin composition; and a support membrane 21. Alternatively, the resin-containing membrane 2 may also be a resin-containing membrane 2 comprising: a resin layer 20 comprising an uncured product of the uncured resin composition; and a support membrane 21.

[0138] The resin layer 20 may or may not contain a fiber substrate (not shown). If the resin layer 20 contains a fiber substrate, the fiber substrate may be the same as the fiber substrate 11 of the prepreg 1. That is, the resin layer may be made from the prepreg 1.

[0139] The support film 21 supports the resin layer 20. In this way, the support film 21 supports the resin layer 20, making the resin layer 20 easier to process.

[0140] For example, the support film 21 can be, but is not limited to, an electrically insulating film. Examples of support films 21 include, but are not limited to, polyethylene terephthalate (PET) films, polyimide films, polyester films, polyparabanic acid films, polyetheretherketone films, polyphenylene sulfide films, polyamide films, polycarbonate films, and polyarylate films.

[0141] Optionally, a release agent layer (not shown) may be provided on the surface of the support film 21 that supports the resin layer 20. The release agent layer allows the support film 21 to be peeled off from the resin layer 20 as needed. Preferably, the support film 21 is peeled off from the insulating layer after the resin layer 20 has cured to form an insulating layer.

[0142] Despite Figure 2 In the example shown, one surface of the resin layer 20 is covered with a support film 21, but as Figure 3 As shown, the other surface of the resin layer 20 can be covered with a covering film 22. Covering both surfaces of the resin layer 20 in this way makes it even easier to process the resin layer 20. This also reduces the possibility of foreign particles adhering to the resin layer 20.

[0143] For example, the cover film 22 can be, but is not limited to, an electrically insulating film. Examples of cover film 22 include, but are not limited to, polyethylene terephthalate (PET) film, polyolefin film, polyester film, and polymethylpentene film. A release agent layer (not shown) may be further provided between the resin layer 20 and the cover film 22. The release agent layer enables the cover film 22 to be peeled off from the resin layer 20 as needed.

[0144] Optionally, the support film 21 and the cover film 22 may be surface treated as needed, such as matte treatment, corona treatment, release treatment and roughening treatment.

[0145] The thickness of the resin layer 20 is, but not limited to, preferably equal to or less than 120 μm, more preferably equal to or less than 100 μm, even more preferably equal to or less than 60 μm, and even more preferably equal to or less than 40 μm. This allows for a reduction in the thickness of the insulating layer, thereby reducing the thickness of the printed circuit board 5. It is also preferred that the thickness of the resin layer is equal to or greater than 10 μm.

[0146] The resin layer 20 is manufactured by coating a resin composition onto a support film 21. Methods for coating the resin composition include, but are not limited to, using a bar coater, die coater, doctor blade, or baker applicator. When coating the resin layer 20 onto the support film 21, a resin composition in the form of a varnish is preferred. As described above, heating the varnish coated onto the support film 21 allows the organic solvent to evaporate from the varnish, thereby reducing or removing the organic solvent content in the varnish. For example, the varnish thus coated is heated at a temperature equal to or higher than 80°C and equal to or lower than 180°C for a time equal to or longer than 1 minute and equal to or shorter than 10 minutes. In other words, the conditions for reducing or removing the organic solvent content in the resin layer 20 by heating the resin layer 20 can be the same as the conditions for reducing or removing the organic solvent content in the resin layer 10 by heating the resin layer 10 during the manufacture of the prepreg 1. In this manner, a resin layer 20 comprising at least one of a resin composition or a semi-cured product of a resin composition is formed on the support film 21, thereby producing a film 2 having a resin.

[0147] Note that this is merely an exemplary method for manufacturing a resin-containing membrane 2 (which includes: a resin layer 20 comprising a resin composition or a semi-cured product of a resin composition according to this embodiment; and a support membrane 21 supporting the resin layer 20) and should not be construed as limiting. That is, the resin-containing membrane 2 can be manufactured using the resin composition according to this embodiment by any other suitable method.

[0148] Note that as long as the resin-containing film 2 is manufactured using a conventional manufacturing method, the surface roughness of the cured product of the resin layer 20 does not affect the reflectivity. That is, the reflectivity of the cured product of the resin layer 20 is not affected by surface roughness, but depends solely on the chemical composition of the resin composition. Therefore, regardless of its surface roughness, the cured product of the resin layer 20 manufactured using the above-described resin composition can reflect light with a wavelength equal to or greater than 365 nm and equal to or less than 405 nm with a reflectivity equal to or less than 20%. The surface roughness of the cured product of the resin layer 20 can be expressed, for example, by an arithmetic mean roughness Sa. The arithmetic mean roughness Sa can be, but is not limited to, equal to or greater than 0.01 μm and equal to or less than 2 μm.

[0149] The resin layer 20 of the resin-containing film 2 according to this embodiment is manufactured using the resin composition according to this embodiment. Therefore, the glass transition temperature of the cured product of the resin composition can be increased to a temperature equal to or higher than 200°C, ensuring good stain resistance of the cured product of the resin composition. The reflectivity of the cured product of the resin composition for light with wavelengths equal to or greater than 365 nm and equal to or less than 405 nm can be reduced to below 20%, and good small-diameter opening properties of the solder resist 8 to be formed on the printed circuit board 5 manufactured using the resin composition can be ensured. Note that the resin-containing film 2 according to this embodiment can be used not only for manufacturing printed circuit boards 5 but also for various other applications.

[0150] (2.3) Metal foil containing resin

[0151] Figure 4 An exemplary resin-containing metal foil sheet 3 according to this embodiment is shown. The resin-containing metal foil sheet 3 generally has the shape of a film or sheet. For example, the resin-containing metal foil sheet 3 can be used to form a multilayer printed circuit board 5 (by stacking).

[0152] The resin-containing metal foil sheet 3 includes: a resin layer 30 comprising at least one of a resin composition or a semi-cured product of a resin composition; and a metal foil sheet 31. Optionally, the resin-containing metal foil sheet 3 may include other layers disposed between the resin layer 30 and the metal foil sheet 31.

[0153] The resin layer 30 may contain a semi-cured product of the resin composition as described above or an uncured product of the uncured resin composition, either case is suitable. That is, the resin-containing metal foil sheet 3 may include: a resin layer 30 containing a semi-cured product of the resin composition; and a metal foil sheet 31. Alternatively, the resin-containing metal foil sheet 3 may also include: a resin layer 30 containing an uncured product of the uncured resin composition; and a metal foil sheet 31.

[0154] The resin layer 30 may or may not contain a fiber substrate (not shown). If the resin layer 30 contains a fiber substrate, the fiber substrate may be the same as the fiber substrate 11 of the prepreg 1. That is, the resin layer 30 may be made of the prepreg 1.

[0155] Examples of metal foil sheet 31 include, but are not limited to, copper foil sheet and aluminum foil sheet. For example, metal foil sheet 31 can be used as conductor line 51 of printed circuit board 5 by etching away the unwanted parts using a subtractive process.

[0156] Optionally, the resin-containing metal foil sheet 3 may also include a cover film (not shown). The cover film may be, for example, the same as the cover film used to manufacture the resin-containing film 2 described above.

[0157] The resin layer 30 is manufactured by coating a resin composition onto a metal foil sheet 31. Methods for coating the resin composition include, but are not limited to, using a bar coater, die coater, doctor blade, or Becker coater. When coating the resin composition onto the metal foil sheet 31, a resin composition in the form of a varnish is preferred.

[0158] As described above, heating the varnish coated onto the metal foil sheet 31 allows the organic solvent to evaporate from the varnish, thereby reducing or removing the organic solvent content in the varnish. For example, the varnish thus coated can be heated at a temperature equal to or higher than 80°C and equal to or lower than 180°C for a time equal to or longer than 1 minute and equal to or shorter than 10 minutes. In other words, the conditions for reducing or removing the organic solvent content in the resin layer 30 by heating the resin layer 30 can be the same as the conditions for reducing or removing the organic solvent content in the resin layer 10 by heating the resin layer 10 during the manufacture of the prepreg 1.

[0159] Note that this is merely an exemplary method for manufacturing a resin-containing metal foil sheet 3 (which includes: a resin layer 30 comprising a resin composition or a semi-cured product of a resin composition according to this embodiment; and a metal foil sheet 31 attached to the resin layer 30), and should not be construed as limiting. That is, the resin-containing metal foil sheet 3 can be manufactured using the resin composition according to this embodiment by any other suitable method.

[0160] Note that as long as the metal foil sheet 3 containing resin is manufactured by a conventional manufacturing method, the surface roughness of the cured product of resin layer 30 does not affect the reflectivity. That is, the reflectivity of the cured product of resin layer 30 is not affected by surface roughness, but depends solely on the chemical composition of the resin composition. Therefore, regardless of its surface roughness, the cured product of resin layer 30 manufactured using the above-described resin composition can reflect light with a wavelength equal to or greater than 365 nm and equal to or less than 405 nm with a reflectivity equal to or less than 20%. The surface roughness of the cured product of resin layer 30 can be expressed, for example, by an arithmetic mean roughness Sa. For example, the arithmetic mean roughness Sa can be, but is not limited to, equal to or greater than 0.01 μm and equal to or less than 2 μm.

[0161] The resin layer 30 of the resin-containing metal foil sheet 3 according to this embodiment is manufactured using the resin composition according to this embodiment. Therefore, the glass transition temperature of the cured product of the resin composition can be increased to a temperature equal to or higher than 200°C, ensuring good stain resistance of the cured product of the resin composition. The reflectivity of the cured product of the resin composition for light with wavelengths equal to or greater than 365 nm and equal to or less than 405 nm can be reduced to below 20%, and good small-diameter opening properties of the solder resist 8 to be formed on the printed circuit board 5 manufactured using the resin composition can be ensured. Note that the resin-containing metal foil sheet 3 according to this embodiment can be used not only for manufacturing printed circuit boards but also for various other applications.

[0162] (2.4) Metal-coated laminate

[0163] Figure 5 An exemplary metal-clad laminate 4 according to this embodiment is shown. The metal-clad laminate 4 includes: an insulating layer 40 comprising a cured product of a resin composition according to this embodiment; and a metal layer 41 stacked on the insulating layer 40. For example, the metal-clad laminate 4 can be used as a material for a printed circuit board 5.

[0164] An exemplary method for manufacturing a metal-clad laminate 4 may include, for example, stacking a resin composition or a semi-cured product of the resin composition and a metal layer 41 together, and heating the assembly under pressure to cure the resin composition and thereby transform the assembly into an insulating layer 40. More specifically, the metal layer 41 (e.g., a copper foil sheet) is stacked on either or both surfaces of the resin composition or the semi-cured product of the resin composition, and the resin composition or the semi-cured product of the resin composition and the metal layer 41 are subjected to a molding process under heat and pressure to cure the resin composition and thereby form the insulating layer 40. The insulating layer 40 comprising the cured product of the resin composition and the metal layer 41 are then stacked together and integrated. In this manner, a metal-clad laminate 4 can be manufactured, wherein the metal layer 41 is attached to either or both surfaces of the insulating layer 40 comprising the cured product of the resin composition.

[0165] Alternatively, the insulation layer 40 can be manufactured using the prepreg 1 described above. More specifically, the prepreg 1 and the metal layer 41 are subjected to a molding process under heat and pressure to cure the prepreg 1 and thereby form the insulation layer 40. Then, the insulation layer 40 and the metal layer 41, which are the cured products containing the prepreg 1, are stacked together and integrated. In this way, a metal-clad laminate 4 can be manufactured, wherein the metal layer 41 is attached to any one or both surfaces of the insulation layer 40, which is the cured product containing the prepreg 1. If the metal-clad laminate 4 is manufactured using the prepreg 1, then as Figure 5 As shown, the metal-clad laminate 4 includes a fiber substrate 42 within the insulating layer 40. The metal-clad laminate 4 may include only one fiber substrate 42, or it may include two or more fiber substrates 42, either way is suitable.

[0166] Alternatively, the insulating layer 40 can also be manufactured using the aforementioned resin-containing film 2 and resin-containing metal foil sheet 3. More specifically, the resin layer 20 of the resin-containing film 2 or the resin layer 30 and metal layer 41 of the resin-containing metal foil sheet 3 are subjected to a molding process under heat and pressure to cure the resin layer 20 of the resin-containing film 2 or the resin layer 30 of the resin-containing metal foil sheet 3, thereby forming the insulating layer 40. Then, the insulating layer 40 and metal layer 41, which contain the cured product of the resin layer 20 of the resin-containing film 2 or the cured product of the resin layer 30 of the resin-containing metal foil sheet 3, are stacked together and integrated. In this way, a metal-coated laminate 4 can be manufactured, wherein the metal layer 41 is attached to any one or both surfaces of the insulating layer 40, which contains the cured product of the resin layer 20 of the resin-containing film 2 or the cured product of the resin layer 30 of the resin-containing metal foil sheet 3. If the metal-clad laminate 4 is manufactured using a resin-containing metal foil sheet 3, then the metal foil sheet 31 of the resin-containing metal foil sheet 3 serves as the metal layer 41 of the metal-clad laminate 4.

[0167] When manufacturing the metal-clad laminate 4, the heating and pressurizing conditions can be appropriately set according to, for example, the thickness of the metal-clad laminate 4 to be manufactured and the type and composition of the resin composition forming the insulating layer 40.

[0168] The heating temperature for manufacturing the metal-clad laminate 4 is preferably equal to or higher than 200°C and equal to or lower than 250°C. Furthermore, the pressure for manufacturing the metal-clad laminate 4 is preferably equal to or higher than 1 MPa and equal to or lower than 5 MPa. Additionally, the heating and pressurizing time for manufacturing the metal-clad laminate 4 is preferably equal to or longer than 30 minutes and equal to or shorter than 120 minutes.

[0169] When manufacturing the metal-coated laminate 4, the thickness of the metal layer 41 can be set to a suitable value according to the intended use. For example, the thickness of the metal layer 41 can be, but is not limited to, equal to or greater than 5 μm and equal to or less than 35 μm. If an extremely thin metal foil sheet is used as the metal layer 41, the extremely thin metal foil sheet can be a metal foil sheet with a carrier (which includes a peelable layer and a carrier) to improve processability.

[0170] Furthermore, this is merely an exemplary method for manufacturing a metal-clad laminate 4 (which includes: an insulating layer 40 comprising a cured product of a resin composition or prepreg 1 according to this embodiment; and a metal layer 41 attached to the insulating layer 40) and should not be construed as limiting. That is, the metal-clad laminate 4 can be manufactured using any other suitable method using the resin composition or prepreg 1 according to this embodiment.

[0171] Note that as long as the metal-clad laminate 4 is manufactured using conventional manufacturing methods, the surface roughness of the insulating layer 40 does not affect the reflectivity. That is, the reflectivity of the insulating layer 40 is not affected by surface roughness, but depends solely on the chemical composition of the resin composition. Therefore, the insulating layer 40 manufactured using the aforementioned resin composition can reflect light with a wavelength equal to or greater than 365 nm and equal to or less than 405 nm with a reflectivity equal to or less than 20%, regardless of its surface roughness. The surface roughness of the insulating layer 40 can be expressed, for example, by an arithmetic mean roughness Sa. For example, the arithmetic mean roughness Sa can be, but is not limited to, equal to or greater than 0.01 μm and equal to or less than 2 μm.

[0172] The insulating layer 40 of the metal-clad laminate 4 according to this embodiment is manufactured using the resin composition according to this embodiment or the prepreg 1 according to this embodiment. Therefore, the glass transition temperature of the cured product of the resin composition can be increased to a temperature equal to or higher than 200°C, which ensures good stain resistance of the cured product of the resin composition. The reflectivity of the cured product of the resin composition for light with wavelengths equal to or greater than 365 nm and equal to or less than 405 nm can be reduced to below 20%, and good small-diameter opening properties of the solder resist 8 to be formed on the printed circuit board 5 manufactured using the resin composition or prepreg 1 can be ensured. Note that the metal-clad laminate 4 according to this embodiment can be used not only for manufacturing printed circuit boards 5, but also for various other applications.

[0173] (2.5) Printed Circuit Board

[0174] Figure 6 An exemplary printed circuit board 5 according to this embodiment is shown. The printed circuit board 5 includes: an insulating layer 50 comprising a cured product of a resin composition; and conductor lines 51 stacked on the insulating layer 50. The conductor lines 51 may be formed on only one surface of the insulating layer 50, or may be formed on each of the two surfaces of the insulating layer 50, either case is suitable.

[0175] The insulating layer 50 may contain the cured product of the prepreg 1 described above. That is, the printed circuit board 5 includes: an insulating layer 50 manufactured using prepreg 1; and conductor lines 51 stacked on the insulating layer 50. The conductor lines 51 may be formed on only one surface of the insulating layer 50, or they may be formed on each of the two surfaces of the insulating layer 50; either case is suitable. If the printed circuit board 5 is manufactured using prepreg 1, then as... Figure 6 As shown, the printed circuit board 5 includes a fiber substrate 52. The printed circuit board 5 may include only one fiber substrate 52, or it may include two or more fiber substrates 52, either way is suitable.

[0176] Alternatively, the printed circuit board 5 can also be manufactured using the metal-clad laminate 4 described above. More specifically, for example, the conductor lines 51 can be formed by etching the metal layer 41 on the surface of the metal-clad laminate 4. That is, the conductor lines 51 of the printed circuit board 5 can be formed by partially removing the metal layer 41 on the surface of the metal-clad laminate 4. In this way, a printed circuit board 5 comprising an insulating layer 50 and conductor lines 51 formed as circuits on either surface of the insulating layer 50 or on each of the two surfaces of the insulating layer 50 can be manufactured.

[0177] Examples of alternative methods for forming circuits other than those described above include, but are not limited to, circuit forming methods using semi-additive processing (SAP) or modified semi-additive processing (MSAP).

[0178] Note that as long as the printed circuit board 5 is manufactured using conventional manufacturing methods, the surface roughness of the insulating layer 50 will not affect the reflectivity. That is, the reflectivity of the insulating layer 50 is not affected by surface roughness, but depends solely on the chemical composition of the resin composition. Therefore, the insulating layer 50 manufactured using the aforementioned resin composition, regardless of its surface roughness, can reflect light with a wavelength equal to or greater than 365 nm and equal to or less than 405 nm with a reflectivity equal to or less than 20%. The surface roughness of the insulating layer 50 can be expressed, for example, by an arithmetic mean roughness Sa. For example, the arithmetic mean roughness Sa can be, but is not limited to, equal to or greater than 0.01 μm and equal to or less than 2 μm.

[0179] The insulating layer 50 of the printed circuit board 5 according to this embodiment is manufactured using the resin composition according to this embodiment or the prepreg 1 according to this embodiment. Therefore, the glass transition temperature of the cured product of the resin composition can be increased to a temperature equal to or higher than 200°C, good stain resistance of the cured product of the resin composition can be ensured, the reflectivity of the cured product of the resin composition for light with wavelengths equal to or greater than 365 nm and equal to or less than 405 nm can be reduced to below 20%, and good small diameter opening properties of the solder resist 8 to be formed on the printed circuit board 5 manufactured using the resin composition or prepreg 1 can be ensured.

[0180] 3. Aspects

[0181] As can be seen from the foregoing description of the embodiments, this disclosure has the following aspects. In the following description, the use of reference numerals in parentheses is solely intended to clarify the correspondence between the following aspects of this disclosure and the constituent elements of the above exemplary embodiments.

[0182] The resin composition according to the first aspect contains a thermosetting resin (A), a coumarin compound (B), and an inorganic filler (C). The thermosetting resin (A) comprises an epoxy resin (A1) and a maleimide resin (A2). The content of maleimide resin (A2) relative to the total mass of the thermosetting resin (A) is equal to or greater than 8% by mass and equal to or less than 60% by mass.

[0183] This aspect not only enables the cured product of the resin composition to have a high glass transition temperature and good stain resistance, but also ensures good small-diameter opening properties of the solder resist (8) to be formed on the printed circuit board (5) made using the resin composition.

[0184] The second aspect is a resin composition that can be implemented in conjunction with the first aspect. In the second aspect, the coumarin compound (B) comprises a coumarin compound (B1) represented by at least one of the following formulas (1) and (2):

[0185] [Chemical Formula 3]

[0186]

[0187] [Chemical Formula 4]

[0188]

[0189] In formulas (1) and (2), R1 and R2 each independently represent a hydrogen atom, an alkyl group, an aryl group, or a hydroxyalkyl group, and R3, R4, and R5 each independently represent a hydrogen atom, an alkyl group, or an aryl group.

[0190] The third aspect is a resin composition that can be implemented in combination with the first or second aspect. In the third aspect, the mass ratio of epoxy resin (A1) to maleimide resin (A2) is from 10:1 to 2:5.

[0191] The fourth aspect is a resin composition that can be implemented in combination with any of the first to third aspects. In the fourth aspect, the epoxy resin (A1) includes at least one selected from the group consisting of: biphenyl epoxy resin, naphthalene epoxy resin, and dicyclopentadiene epoxy resin.

[0192] The fifth aspect is a resin composition that can be implemented in combination with any of the first to fourth aspects. In the fifth aspect, the thermosetting resin (A) further comprises a phenolic resin (A3).

[0193] The sixth aspect is a resin composition that can be implemented in combination with any of the first to fifth aspects. In the sixth aspect, the content of coumarin compound (B) is equal to or greater than 0.4% by mass and equal to or less than 10% by mass relative to the total mass of the thermosetting resin (A) and the coumarin compound (B).

[0194] The seventh aspect is a resin composition that can be implemented in combination with any of the first to sixth aspects. In the seventh aspect, the content of inorganic filler (C) is equal to or greater than 50 parts by mass and equal to or less than 300 parts by mass relative to a total of 100 parts by mass of thermosetting resin (A) and coumarin compound (B).

[0195] The eighth aspect is a resin composition that can be implemented in combination with any of the first to seventh aspects. In the eighth aspect, the resin composition further comprises an amine compound (D) that does not have a coumarin skeleton.

[0196] The ninth aspect is a resin composition that can be implemented in combination with any of the first to eighth aspects. In the ninth aspect, the resin composition further comprises a core-shell rubber (E).

[0197] The tenth aspect is a resin composition that can be implemented in combination with any of the first to ninth aspects. In the tenth aspect, the inorganic filler (C) includes at least one filler selected from the group consisting of: silica, talc, boehmite, magnesium hydroxide, and aluminum hydroxide.

[0198] The prepreg (1) according to the eleventh aspect comprises: at least one of the resin composition or semi-cured product of the resin composition according to any one of the first to tenth aspects; and a fiber substrate (11).

[0199] The resin-containing membrane (2) according to the twelfth aspect comprises: a resin layer (20) containing at least one of the resin compositions or semi-cured products of the resin compositions according to any one of the first to tenth aspects; and a support membrane (21).

[0200] The resin-containing metal foil sheet (3) according to the thirteenth aspect comprises: a resin layer (30) containing at least one of the resin compositions or semi-cured products of the resin compositions according to any one of the first to tenth aspects; and a metal foil sheet (31).

[0201] The metal-clad laminate (4) according to the fourteenth aspect comprises: an insulating layer (40) comprising a cured product of a resin composition according to any one of the first to tenth aspects; and a metal layer (41).

[0202] The metal-clad laminate (4) according to the fifteenth aspect comprises: an insulating layer (40) containing a cured product of the prepreg (1) according to the eleventh aspect; and a metal layer (41).

[0203] The printed circuit board (5) according to the sixteenth aspect includes: an insulating layer (50) comprising a cured product of a resin composition according to any one of the first to tenth aspects; and conductor lines (51).

[0204] The printed circuit board (5) according to the seventeenth aspect includes: an insulating layer (50) comprising a cured product of a prepreg (1) according to the eleventh aspect; and conductor lines (51).

[0205] Example

[0206] The present disclosure will now be described in detail by way of illustrative embodiments. Note that the following are merely embodiments of the present disclosure and should not be construed as limiting.

[0207] (1) Resin composition

[0208] The components shown in Tables 1 and 2 below were used as raw materials for the resin compositions. Thermosetting resin (A), coumarin compound (B), inorganic filler (C), amine compound (D), and core-shell rubber (E) were blended to obtain the compositions shown in Tables 1 and 2, diluted with a solvent (methyl ethyl ketone), and homogenized by stirring and mixing to prepare the resin compositions in varnish form according to the examples and comparative examples. Details of the components used are as follows:

[0209] (1.1) Thermosetting resin (A)

[0210] <Epoxy Resin (A1)>

[0211] • Epoxy Resin #1: Naphthalene epoxy resin, product name "EPICLON HP-9500", manufactured by DIC Corporation, with an epoxy equivalent of 220-240 g / eq.;

[0212] • Epoxy Resin #2: Biphenyl epoxy resin, product name "NC-3500", manufactured by Nippon Kayaku Co., Ltd., with an epoxy equivalent of 209 g / eq.; and

[0213] • Epoxy Resin #3: Biphenyl epoxy resin, product name "NC-3000H", manufactured by Nippon Kayaku Co., Ltd., with an epoxy equivalent of 280-300 g / eq.

[0214] <Maleimide Resin (A2)>

[0215] • Maleimide resin #1: Product name "BMI-2300", manufactured by Daiwa Kasei Kogyo Co., Ltd.; and

[0216] Maleimide resin #2: Product name "MIR-3000-70MT", manufactured by Nippon Kayaku Co., Ltd.

[0217] <Phenolic Resin (A3)>

[0218] • Phenolic resin #1: Biphenyl phenolic resin, product name "GPH-103", manufactured by Nippon Kayaku Co., Ltd., with a phenolic hydroxyl equivalent of 231 g / eq.;

[0219] • Phenolic resin #2: Phosphorus-containing phenolic resin, product name "XZ92741", manufactured by Dow Chemical Japan Co., Ltd., with a phenolic hydroxyl equivalent of 550 g / eq.; and

[0220] • Phenolic resin #3: Biphenyl phenolic resin, product name "MEHC-7403H", manufactured by Meiwa Plastic Industries, Ltd., with a phenolic hydroxyl equivalent of 132 g / eq.

[0221] (1.2) Coumarin compounds (B)

[0222] • Coumarin compound #1: Compound name "7-amino-4-methylcoumarin", manufactured by Tokyo Chemical Industry Co., Ltd.

[0223] (1.3) Inorganic filler (C)

[0224] • Inorganic filler #1: Aminosilane treated silica, product name "SC2500-SXJ", produced by Admatechs Co., Ltd., with an average particle size (D50) of 0.5 μm.

[0225] (1.4) Amine compounds (D)

[0226] • Amine compound #1: Compound name "2-ethyl-4-methylimidazole", product name "2E4MZ", manufactured by Shikoku Chemicals Corporation.

[0227] (1.5) Core-shell type rubber

[0228] • Core-shell type rubber #1: Product name "SRK200A", manufactured by Mitsubishi Chemical Corporation, core: silicone resin, shell: styrene-acrylonitrile copolymer, average particle size (D50) is 0.15 μm.

[0229] (2) Prepreg

[0230] As the fiber substrate, glass cloth (#2118 type, WEA2118T-107-S199, E glass, manufactured by NittoBoseki Co., Ltd.) is provided. The glass cloth sheet is a textile sheet woven with warp and weft yarns substantially perpendicular to each other. This glass cloth sheet is impregnated with a resin composition in the form of a varnish, such that the thickness of the cured prepreg product will be 100 μm. Next, the resin composition impregnated in the glass cloth sheet is heated and dried at 130°C using a non-contact heating unit until the resin composition becomes a semi-cured product. In this manner, the solvent is removed from the resin composition, thereby obtaining a prepreg comprising the glass cloth sheet and the semi-cured product of the resin composition impregnated in the glass cloth sheet. The content of the resin layer 10 in the prepreg is 46% by mass relative to 100% by mass of the entire prepreg.

[0231] (3) Metal-coated laminate

[0232] Two prepregs obtained as described above are stacked together to obtain a prepreg stack. A copper foil sheet (3EC-VLP-12, manufactured by Mitsui Mining and Smelting Co., Ltd., with a thickness of 12 μm) is laminated as a metal layer onto each of the two surfaces of the resulting stack, thereby forming a prepreg stack with the copper foil sheet. The prepreg stack with the copper foil sheet is then formed under heat and pressure to obtain a metal-coated laminate with a thickness of 0.2 mm and including a metal layer on each of its two surfaces. The forming process under heat and pressure is carried out under conditions including 220°C, 2 MPa, and 90 minutes.

[0233] (4) Experiment

[0234] (4.1) Glass transition temperature

[0235] The copper foil sheet already attached to both surfaces of the metal-coated laminate was etched away to obtain an uncoated plate. The uncoated plate was cut at a 45-degree angle relative to the warp and weft yarns of the glass cloth sheet, thus obtaining a test piece with dimensions of 50 mm × 5 mm × 0.2 mm.

[0236] The tanδ of this specimen was measured using a dynamic mechanical spectrometer (“DMS6100”, manufactured by SII Nanotechnology Inc.) at a heating rate of 5 °C / min (by dynamic mechanical analysis (DMA)). Its peak temperature is considered to be its glass transition temperature.

[0237] (4.2) Reflectivity

[0238] The copper foil sheets already attached to both surfaces of the metal-clad laminate were etched away to obtain an unclad board. A test piece with dimensions of 50 mm × 50 mm × 0.2 mm was obtained from this unclad board.

[0239] For this test specimen, the reflectance of light with wavelengths of 365 nm, 385 nm, 395 nm, and 405 nm was measured in the thickness direction defined for the test specimen using a UV-Vis spectrophotometer (“UV-2500PC”, manufactured by Shimadzu Corporation). The reflectance measurements were performed in reflectance measurement mode using an integrating sphere attachment (integrating sphere inner diameter: Φ60 mm, barium sulfate coated type) at a 5° incident angle, and the results are relative total reflectance measurements.

[0240] (4.3) Small diameter opening properties of solder resist

[0241] First, a copper foil sheet bonded to a 5 cm × 5 cm metal-coated laminate was etched away to form an uncoated board. Using a vacuum laminator, a photosensitive dry film solder resist (PSR-800 AUS410, manufactured by Taiyo Ink Mfg. Co., Ltd., 20 μm thick, negative type) was adhered to the entire surface of this uncoated board under conditions including a lamination temperature of 75°C, a vacuum holding time of 20 seconds, and a pressurization time of 60 seconds to obtain a test piece.

[0242] Then, using an exposure system equipped with a metal halide lamp (“HMW-680 GW20”, manufactured by ORC Manufacturing Co., Ltd.), the resulting test piece was passed through a photomask (with an opening pattern of 100 μm or 60 μm in diameter) at 20°C at 600 mJ / cm². 2 The cumulative exposure dose is exposed to exposure radiation, thereby curing the dry film solder resist. Note that... Figure 7-9 The unilluminated inner edge 6 shown refers to the inner edge of the portion that is not illuminated by light with a wavelength equal to or greater than 365 nm and equal to or less than 405 nm due to the photomask.

[0243] After exposure, the test specimens were developed by spray development. The development process involved spraying a 1% sodium bicarbonate aqueous solution at 30°C as the developer at a spray pressure of 0.2 MPa for 120 seconds. After development, the test specimens were rinsed with water at 25°C at a spray pressure of 0.1 MPa for 45 seconds. After rinsing with water, the specimens underwent a post-curing treatment at 150°C for 60 minutes and a high-pressure mercury lamp with a heat output of 1000 mJ / cm². 2 The post-UV treatment cures the dry film solder resist. Note that post-curing and post-UV treatments are performed to further cure the dry film solder resist after exposure. Through these treatments, solder resist 8 is formed on the test piece.

[0244] The unilluminated inner edge 6 of each test piece was then observed by scanning electron microscopy (SEM), and the observation results were classified according to the following evaluation criteria to evaluate the solder resist openness of each test piece.

[0245] <Evaluation Criteria>

[0246] Grade S: For both 60 μm spot diameter Φ and 100 μm spot diameter Φ, holes can be formed in the solder resist in the desired shape;

[0247] Grade A: Only for spot diameters Φ of 100 μm, it is possible to create holes of the desired shape in the solder resist; or

[0248] Grade B: For a spot diameter Φ of 100 μm, a hole cannot be formed in the solder resist in the desired shape.

[0249] According to these evaluation criteria, the statement "able to create a hole in the solder resist in the desired shape" means, for example... Figure 7 As shown, for each spot diameter, no solder resist 8 remains inside the unirradiated inner edge 6, and the hole 7 is formed in a roughly circular shape. On the other hand, the statement "the hole cannot be formed in the expected shape in the solder resist" means that... Figure 8 As shown, for a spot diameter Φ of 100 μm, the solder resist 8 remains inside the unirradiated inner edge 6, the hole 7 does not have a circular shape, and the unirradiated inner edge 6 only has a partially opened hole, or as shown... Figure 9 As shown, for a spot diameter Φ of 100 μm, the state is such that no hole 7 is formed and the solder resist 8 remains completely inside the unirradiated inner edge 6. Note that if a hole can be formed in the solder resist 8 in the expected shape for a spot diameter Φ of 100 μm, but not for a spot diameter Φ of 60 μm, the test piece is rated as Grade A.

[0250] If the test piece is rated as Grade S or Grade A, it has good solder resist small diameter opening properties.

[0251] (4.4) Stain resistance

[0252] Desmear resistance is evaluated by the depth of desmear etching, which is calculated based on the difference between the mass of a test piece that has not yet undergone desmear treatment and the mass of a test piece that has undergone desmear treatment with permanganate.

[0253] Specifically, a copper foil sheet attached to a 5 cm × 5 cm metal-coated laminate was etched away to obtain the test piece. The desmearing etching depth was based on the difference (in mg / cm³) between the mass of the test piece before desmearing (initial mass) and the mass of the test piece that had been desmeared under the following conditions. 2 ) to calculate.

[0254] After drying the test specimen at 130°C for 30 minutes and then air-cooling it in a desiccator for 2 hours, the initial mass of the test specimen before the treatment was measured. As a stain removal treatment, the following process steps (a)-(d) were performed:

[0255] (a) Swelling process steps

[0256] First, the initial mass of the untreated test specimen was measured, and then the untreated test specimen was swollen for 5 minutes in “Swelling Dip Securigant P (500 ml / L)” (manufactured by Atotech) and sodium hydroxide aqueous solution (40 g / L).

[0257] (b) Steps for removing stains

[0258] Next, micro-etching was performed for 10 minutes using Concentrate Compact CP (580 ml / L) (manufactured by Atotech) and sodium hydroxide aqueous solution (40 g / L).

[0259] (c) Neutralization process steps

[0260] Next, the solution was neutralized for 5 minutes using "Reduction Solution Securigant P500 (70 ml / L)" (manufactured by Atotech) and sulfuric acid (98%, 50 ml / L).

[0261] (d) Drying process steps

[0262] Finally, the product was dried at 130°C for 30 minutes.

[0263] Repeat steps (a)-(c) twice, then proceed to step (d). After air cooling in a dryer for two hours, measure the quality of the treated test piece. Calculate the depth of the decontamination etching in this manner.

[0264] If the stain removal etching depth is equal to or less than 0.5 mg / cm 2 It has good stain resistance.

[0265] [Table 1]

[0266]

[0267] [Table 2]

[0268]

[0269] List of reference numerals

[0270] 1 Prepreg

[0271] 10 resin layers

[0272] 11 Fiber-based substrate

[0273] 2. Films containing resin

[0274] 20 resin layers

[0275] 21 Supporting membrane

[0276] 3. Resin-containing metal foil sheets

[0277] 30 resin layers

[0278] 31 Metal Foil Sheet

[0279] 4 Metal-coated laminate

[0280] 40 insulation layers

[0281] 41 metal layers

[0282] 42 Fiber-based substrate

[0283] 5 Printed Circuit Boards

[0284] 50 insulation layers

[0285] 51 conductor circuit

[0286] 52 Fiber-based substrate

[0287] 6 Unirradiated inner edge

[0288] 7 holes

[0289] 8 Solder resist

Claims

1. A resin composition comprising a thermosetting resin (A), a coumarin compound (B), and an inorganic filler (C), The thermosetting resin (A) comprises epoxy resin (A1) and maleimide resin (A2), and The content of maleimide resin (A2) is equal to or greater than 8% by mass and equal to or less than 60% by mass relative to the total mass of the thermosetting resin (A).

2. The resin composition according to claim 1, wherein... The coumarin compound (B) comprises a coumarin compound (B1) represented by at least one of the following formulas (1) and (2): [Chemical Formula 1] [Chemical Formula 2] R1 and R2 each independently represent a hydrogen atom, an alkyl group, an aryl group, or a hydroxyalkyl group, and R3, R4, and R5 each independently represent a hydrogen atom, an alkyl group, or an aryl group.

3. The resin composition according to claim 1, wherein... The mass ratio of the epoxy resin (A1) to the maleimide resin (A2) is 10:1 to 2:

5.

4. The resin composition according to claim 1, wherein... The epoxy resin (A1) includes at least one selected from the group consisting of: biphenyl epoxy resin, naphthalene epoxy resin, and dicyclopentadiene epoxy resin.

5. The resin composition according to claim 1, wherein... The thermosetting resin (A) further comprises phenolic resin (A3).

6. The resin composition according to claim 1, wherein... The content of the coumarin compound (B) relative to the total mass of the thermosetting resin (A) and the coumarin compound (B) is equal to or greater than 0.4% by mass and equal to or less than 10% by mass.

7. The resin composition according to claim 1, wherein... The content of the inorganic filler (C) is equal to or greater than 50 parts by mass and equal to or less than 300 parts by mass relative to a total of 100 parts by mass of the thermosetting resin (A) and the coumarin compound (B).

8. The resin composition according to claim 1, wherein the resin composition further comprises an amine compound (D) that does not have a coumarin skeleton.

9. The resin composition according to claim 1, wherein the resin composition further comprises a core-shell rubber (E).

10. The resin composition according to claim 1, wherein... The inorganic filler (C) includes at least one filler selected from the group consisting of: silica, talc, boehmite, magnesium hydroxide, and aluminum hydroxide.

11. A prepreg, the prepreg comprising: At least one of the resin composition according to any one of claims 1 to 10 or the semi-cured product of the resin composition; And fiber-based materials.

12. A resin-containing membrane, said resin-containing membrane comprising: A resin layer comprising at least one of the resin compositions according to any one of claims 1 to 10 or a semi-cured product of the resin composition; And the supporting membrane.

13. A resin-containing metal foil sheet, said resin-containing metal foil sheet comprising: A resin layer comprising at least one of the resin compositions according to any one of claims 1 to 10 or a semi-cured product of the resin composition; And metal foil sheets.

14. A metal-clad laminate, the metal-clad laminate comprising: An insulating layer comprising a cured product of the resin composition according to any one of claims 1 to 10; And a metal layer.

15. A metal-clad laminate, the metal-clad laminate comprising: An insulating layer comprising a cured product of the prepreg of claim 11; And a metal layer.

16. A printed circuit board, the printed circuit board comprising: Insulation layer, The insulating layer comprises a cured product of the resin composition according to any one of claims 1 to 10; And conductor lines.

17. A printed circuit board, the printed circuit board comprising: Insulation layer, The insulating layer comprises a cured product of the prepreg as described in claim 11; And conductor lines.

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