JP7459901B2 - Prepreg and its manufacturing method, laminate, printed wiring board, and semiconductor package - Google Patents

Description

The present invention relates to prepregs and their manufacturing methods, laminates, printed wiring boards, and semiconductor packages.

In recent years, electronic devices have become smaller, lighter and more multifunctional. As a result, LSIs (Large Scale Integration), chip components, etc. have become more highly integrated, and their configurations are rapidly changing to have more pins and smaller sizes. For this reason, development of fine wiring for multilayer printed wiring boards is being promoted in order to improve the mounting density of electronic components. As a manufacturing method for multilayer printed wiring boards that meets these demands, for example, a build-up method of forming wiring layers using prepreg or the like as an insulating layer and connecting only the necessary parts with via holes (hereinafter also referred to as "laser vias") formed by laser irradiation is becoming mainstream as a method suitable for weight reduction, size reduction and fine wiring.

It is important for multilayer printed wiring boards to have high electrical connection reliability between multiple layers of wiring patterns formed with a fine wiring pitch and excellent high frequency characteristics, and also to have high connection reliability with semiconductor chips. sexuality is required. In particular, in recent years, motherboards of multi-functional mobile phone terminals and the like have become significantly thinner and the wiring density has increased significantly, and laser vias used for interlayer connections are required to have smaller diameters.
When connecting layers using small-diameter laser vias, dimensional stability of the substrate is one of the important characteristics. When creating multilayer wiring, each substrate is subjected to heat and stress during lamination multiple times. Therefore, if there are large variations in the dimensions of the boards themselves, especially if there are large variations in the amount of dimensional change between each board due to thermal history, etc., the position of the laser vias will shift each time they are stacked, which can cause defects such as reduced connection reliability. obtain. For this reason, there is a need for a substrate with small variations in the amount of dimensional change.

For example, Patent Document 1 discloses that, for the purpose of improving the conformity between layers in a multilayer printed wiring board, a core made of a base material containing a pre-cured thermosetting resin and having a first surface and a second surface. discloses a prepreg characterized by comprising a first adhesive layer and a second adhesive layer formed on the first and second surfaces of the core, respectively.

Japanese Patent Application Publication No. 2002-103494

However, the prepreg of Patent Document 1 has a problem in that it is inferior in wiring embeddability because it contains a pre-cured thermosetting resin as a core. In addition, the prepreg of Patent Document 1 requires multiple layers with different degrees of curing, which requires a complicated production process, and there is a demand for a prepreg that can be obtained by a simpler method and has less variation in dimensional change.

The present invention aims to provide a prepreg that has excellent moldability and small variation in dimensional change, as well as a manufacturing method thereof, a laminate, a printed wiring board, and a semiconductor package.

The present inventors have conducted extensive research to achieve the above object, and have found that a prepreg produced through a process of carrying out a specific heat treatment has excellent moldability and small variation in dimensional change, thereby completing the present invention. The present invention relates to the following items [1] to [10].
[1] A prepreg obtained through the following steps 1 to 3.
Step 1: A step of obtaining a prepreg precursor. The prepreg precursor is obtained by B-staging a thermosetting resin composition. The B-staging is achieved by impregnating a substrate with the thermosetting resin composition and then subjecting the substrate to a heat treatment.
Step 2: A step of cooling the prepreg precursor obtained in step 1.
Step 3: A step of obtaining a prepreg. The prepreg is obtained by subjecting the prepreg precursor cooled in step 2 to a surface heat treatment. The surface heat treatment is a treatment for increasing the surface temperature of the prepreg precursor.
[2] The prepreg according to the above-mentioned [1], wherein the surface heating treatment in step 3 is a treatment for increasing the surface temperature of the prepreg precursor by 5 to 110°C.
[3] The prepreg according to the above [1] or [2], wherein the surface heating treatment in step 3 is a treatment for heating the surface temperature of the prepreg precursor to 20 to 130° C.
[4] The prepreg according to any one of the above [1] to [3], wherein the surface heating treatment in step 3 is a treatment in which the prepreg precursor is heated in an environment of 200 to 700 ° C.
[5] The prepreg according to any one of [1] to [4] above, wherein the heating time of the surface heat treatment in step 3 is 1.0 to 10.0 seconds.
[6] The prepreg according to any one of the above-mentioned [1] to [5], wherein the base material is a glass cloth.
[7] A laminate obtained by laminating and molding the prepreg according to any one of [1] to [6] above and a metal foil.
[8] A printed wiring board comprising the prepreg according to any one of [1] to [6] above or the laminate according to [7] above.
[9] A semiconductor package using the printed wiring board according to [8] above.
[10] A method for producing the prepreg according to any one of [1] to [6] above, comprising the following steps 1 to 3:
Step 1: A step of obtaining a prepreg precursor. The prepreg precursor is obtained by B-staging a thermosetting resin composition. The B-staging is achieved by impregnating a substrate with the thermosetting resin composition and then subjecting the substrate to a heat treatment.
Step 2: A step of cooling the prepreg precursor obtained in step 1.
Step 3: A step of obtaining a prepreg. The prepreg is obtained by subjecting the prepreg precursor cooled in step 2 to a surface heat treatment. The surface heat treatment is a treatment for increasing the surface temperature of the prepreg precursor.

According to the present invention, it is possible to provide a prepreg with excellent moldability and small variations in dimensional change, a method for manufacturing the same, a laminate, a printed wiring board, and a semiconductor package.

FIG. 2 is a schematic diagram of an evaluation substrate used for measuring the variation in dimensional change in the examples.

In this specification, the lower limit and upper limit of a numerical range can be arbitrarily combined with the lower limit and upper limit of other numerical ranges, respectively. The present invention also includes embodiments in which the items described in this specification are arbitrarily combined.

[Prepreg]
The prepreg of the present invention is a prepreg obtained through the following steps 1 to 3.
Step 1: A step of obtaining a prepreg precursor, the prepreg precursor is made by B-staging a thermosetting resin composition, and the B-staging involves impregnating a base material with the thermosetting resin composition. After that, heat treatment is performed.
Step 2: A step of cooling the prepreg precursor obtained in Step 1.
Step 3: A step of obtaining prepreg, the prepreg is obtained by subjecting the prepreg precursor cooled in Step 2 to surface heat treatment, and the surface heat treatment increases the surface temperature of the prepreg precursor. It is processing.
First, the base material and thermosetting resin composition used in the prepreg of the present invention will be explained, and then the method for manufacturing the prepreg of the present invention will be explained.
In the present invention, the B-stage refers to a state in which the thermosetting resin composition is semi-cured.

<Substrate>
The substrate contained in the prepreg of the present invention is not particularly limited, and may be, for example, a well-known substrate used in various laminates for electrical insulating materials.
Examples of the substrate include natural fibers such as paper and cotton linters; inorganic fibers such as glass fibers and asbestos; organic fibers such as aramid, polyimide, polyvinyl alcohol, polyester, tetrafluoroethylene, and acrylic; and mixtures thereof. Among these, glass fibers are preferred. As the glass fiber substrate, glass woven fabric (glass cloth) is preferred, and examples thereof include woven fabrics using E glass, C glass, D glass, S glass, etc., or glass woven fabrics in which short fibers are bonded with an organic binder; and mixtures of glass fibers and cellulose fibers. More preferred is glass woven fabric using E glass.
These substrates have shapes such as woven fabric, nonwoven fabric, roving, chopped strand mat, surfacing mat, etc. The material and shape are selected depending on the intended use and performance of the molded product, and one type may be used alone, or two or more types of materials and shapes may be combined as necessary.
The thickness of the substrate is, for example, 0.01 to 0.5 mm, and from the viewpoint of formability and enabling high-density wiring, it is preferably 0.015 to 0.2 mm, and more preferably 0.02 to 0.1 mm. From the viewpoints of heat resistance, moisture resistance, processability, etc., it is preferable that these substrates are surface-treated with a silane coupling agent or the like, or mechanically opened.

<Thermosetting Resin Composition>
The thermosetting resin composition contained in the prepreg of the present invention is not particularly limited, and may be, for example, a thermosetting resin composition containing a known thermosetting resin used in prepregs for printed wiring boards.
The thermosetting resin composition contains (A) a thermosetting resin, and preferably further contains one or more selected from the group consisting of (B) a curing agent, (C) a curing accelerator, and (D) an inorganic filler, and more preferably contains (B) a curing agent, (C) a curing accelerator, and (D) an inorganic filler.
Hereinafter, each component that may be contained in the thermosetting resin composition will be described.

((A) Thermosetting resin)
(A) There are no particular limitations on the thermosetting resin, and any thermosetting resin can be appropriately selected and used from those conventionally used as thermosetting resins.
(A) Thermosetting resins include epoxy resins, phenolic resins, maleimide compounds, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, and silicone resins. , triazine resin, melamine resin, etc. Among these, epoxy resins and maleimide compounds are preferred from the viewpoint of moldability and electrical insulation.
(A) The thermosetting resin may be used alone or in combination of two or more.

The epoxy equivalent of the epoxy resin is preferably 100 to 500 g/eq, more preferably 150 to 400 g/eq, and even more preferably 200 to 350 g/eq. Here, the epoxy equivalent is the mass of resin per epoxy group (g/eq), and can be measured according to the method specified in JIS K 7236.

Examples of the epoxy resin include glycidyl ether type epoxy resin, glycidyl amine type epoxy resin, and glycidyl ester type epoxy resin. Among these, glycidyl ether type epoxy resins are preferred.
Epoxy resins are classified into various epoxy resins depending on the main skeleton, and in each of the above types of epoxy resins, there are also bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, etc. Epoxy resin; biphenylaralkyl novolac type epoxy resin, phenol novolak type epoxy resin, alkylphenol novolac type epoxy resin, cresol novolak type epoxy resin, naphthol alkylphenol copolymerized novolac type epoxy resin, naphthol aralkyl cresol copolymerized novolac type epoxy resin, bisphenol A novolak Novolac type epoxy resins such as type epoxy resins and bisphenol F novolac type epoxy resins; stilbene type epoxy resins; triazine skeleton-containing epoxy resins; fluorene skeleton-containing epoxy resins; naphthalene type epoxy resins; anthracene type epoxy resins; triphenylmethane type epoxy resins ; biphenyl type epoxy resin; xylylene type epoxy resin; alicyclic epoxy resin such as dicyclopentadiene type epoxy resin.
Among these, from the viewpoint of moldability and insulation reliability, novolac type epoxy resins are preferred, and biphenylaralkyl novolac type epoxy resins are more preferred.

As the maleimide compound, a maleimide compound (a1) having an N-substituted maleimide group (hereinafter also referred to as "maleimide compound (a1)") is preferred.
Specifically, the maleimide compound (a1) includes, for example, N,N'-ethylene bismaleimide, N,N'-hexamethylene bismaleimide, bis(4-maleimidocyclohexyl)methane, 1,4-bis(maleimide aliphatic hydrocarbon group-containing maleimide such as cyclohexane; N,N'-(1,3-phenylene)bismaleimide, N,N'-[1,3-(2-methylphenylene)]bismaleimide, N, N'-[1,3-(4-methylphenylene)]bismaleimide, N,N'-(1,4-phenylene)bismaleimide, bis(4-maleimidophenyl)methane, bis(3-methyl-4- maleimidophenyl)methane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide, bis(4-maleimidophenyl)ether, bis(4-maleimidophenyl)sulfone, bis(4- maleimidophenyl) sulfide, bis(4-maleimidophenyl)ketone, 1,4-bis(4-maleimidophenyl)cyclohexane, 1,4-bis(maleimidomethyl)cyclohexane, 1,3-bis(4-maleimidophenoxy)benzene , 1,3-bis(3-maleimidophenoxy)benzene, bis[4-(3-maleimidophenoxy)phenyl]methane, bis[4-(4-maleimidophenoxy)phenyl]methane, 1,1-bis[4- (3-Maleimidophenoxy)phenyl]ethane, 1,1-bis[4-(4-maleimidophenoxy)phenyl]ethane, 1,2-bis[4-(3-maleimidophenoxy)phenyl]ethane, 1,2- Bis[4-(4-maleimidophenoxy)phenyl]ethane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]propane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]butane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]butane, 2,2-bis[4-(3-maleimidophenoxy) phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]-1,1,1,3,3,3-hexafluoro Propane, 4,4-bis(3-maleimidophenoxy)biphenyl, 4,4-bis(4-maleimidophenoxy)biphenyl, bis[4-(3-maleimidophenoxy)phenyl]ketone, bis[4-(4-maleimide) phenoxy)phenyl]ketone, 2,2'-bis(4-maleimidophenyl)disulfide, bis(4-maleimidophenyl)disulfide, bis[4-(3-maleimidophenoxy)phenyl]sulfide, bis[4-(4- maleimidophenoxy)phenyl] sulfide, bis[4-(3-maleimidophenoxy)phenyl]sulfoxide, bis[4-(4-maleimidophenoxy)phenyl]sulfoxide, bis[4-(3-maleimidophenoxy)phenyl]sulfone, bis [4-(4-maleimidophenoxy)phenyl]sulfone, bis[4-(3-maleimidophenoxy)phenyl]ether, bis[4-(4-maleimidophenoxy)phenyl]ether, 1,4-bis[4-( 4-Maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(3- maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(3-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(4-maleimidophenoxy) )-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,4 -bis[4-(3-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(3-maleimidophenoxy)-3,5-dimethyl-α, Examples include aromatic hydrocarbon group-containing maleimides such as α-dimethylbenzyl]benzene and polyphenylmethanemaleimide.
Among these, bis(4-maleimidophenyl)methane, bis(4-maleimidophenyl)sulfone, bis(4-maleimidophenyl)sulfide, and bis(4-maleimidophenyl)sulfide have a high reaction rate and can achieve higher heat resistance. -maleimidophenyl) disulfide, N,N'-(1,3-phenylene)bismaleimide, and 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane are preferred; (4-Maleimidophenyl)methane and N,N'-(1,3-phenylene)bismaleimide are preferred, and from the viewpoint of solubility in solvents, bis(4-maleimidophenyl)methane is particularly preferred.

The maleimide compound is preferably a maleimide compound having an N-substituted maleimide group obtained by reacting a maleimide compound (a1), a monoamine compound (a2) having an acidic substituent, and a diamine compound (a3).
Examples of the monoamine compound (a2) having an acidic substituent include o-aminophenol, m-aminophenol, p-aminophenol, o-aminobenzoic acid, m-aminobenzoic acid, p-aminobenzoic acid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid, 3,5-dihydroxyaniline, and 3,5-dicarboxyaniline.
Examples of the diamine compound (a3) include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylpropane, 2,2'-bis[4,4'-diaminodiphenyl]propane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylethane, 3,3'-diethyl-4,4'-diaminodiphenylethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylthioether, 3,3'-dihydroxy-4,4'-diaminodiphenylmethane, 2,2',6,6'-tetramethyl-4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 3,3'-dibromo-4,4'-diaminodiphenylmethane, 2,2',6,6'-tetramethylchloro-4,4'-diaminodiphenylmethane, 2,2',6,6'-tetrabromo-4,4'-diaminodiphenylmethane, etc. Among these, 4,4'-diaminodiphenylmethane and 3,3'-diethyl-4,4'-diaminodiphenylmethane are preferred from the viewpoint of inexpensiveness, and 4,4'-diaminodiphenylmethane is more preferred from the viewpoint of solubility in a solvent.

In the reaction of the maleimide compound (a1), the monoamine compound (a2) having an acidic substituent, and the diamine compound (a3), it is preferable that the amounts of the three compounds used are such that the relationship between the sum of the primary amino group equivalents [referred to as —NH ₂ group equivalent] of the monoamine compound (a2) having an acidic substituent and the diamine compound (a3) and the maleimide group equivalent of the maleimide compound (a1) satisfies the following formula:
0.1≦[maleimide group equivalent]/[total of ₂ -NH group equivalents]≦10
By making the [maleimide group equivalent]/[sum of _two -NH group equivalents] 0.1 or more, gelation and heat resistance are not reduced, and by making it 10 or less, solubility in organic solvents, adhesion to metal foil and heat resistance are not reduced, which are preferable.
From the same viewpoint, more preferably,
The following condition is satisfied: 1≦[maleimide group equivalent]/[total of ₂ -NH group equivalents]≦9, and more preferably,
The following condition is satisfied: 2≦[maleimide group equivalent]/[total of _two —NH group equivalents]≦8.

The content of the thermosetting resin (A) in the thermosetting resin composition is preferably 15 to 80 parts by mass, and 25 to 70 parts by mass, based on 100 parts by mass of the resin component in the thermosetting resin composition. is more preferable, and even more preferably 35 to 60 parts by mass. The resin components in the thermosetting resin composition include, for example, (A) a thermosetting resin, (B) a curing agent, and (C) a curing accelerator.

((B) Curing agent)
The thermosetting resin composition may contain (B) a curing agent in order to cure the (A) thermosetting resin. There are no particular limitations on the curing agent (B), and any curing agent can be appropriately selected from those conventionally used as curing agents for thermosetting resins.
(B) The curing agent may be used alone or in combination of two or more.
(B) When using an epoxy resin as the thermosetting resin (A), examples of the curing agent include phenolic resin curing agents, acid anhydride curing agents, amine curing agents, dicyandiamide, cyanate resin curing agents, etc. It will be done. Among these, phenolic resin curing agents are preferred from the viewpoint of moldability and insulation reliability.

The phenolic resin-based curing agent is not particularly limited as long as it is a phenolic resin having two or more phenolic hydroxyl groups in one molecule, and examples thereof include compounds having two phenolic hydroxyl groups in one molecule, such as resorcin, catechol, bisphenol A, bisphenol F, and biphenol; aralkyl-type phenolic resins; dicyclopentadiene-type phenolic resins; triphenylmethane-type phenolic resins; novolac-type phenolic resins such as phenol novolac resins, cresol novolac resins, and aminotriazine-modified novolac-type phenolic resins; resol-type phenolic resins; copolymerized phenolic resins of benzaldehyde-type phenols and aralkyl-type phenols; p-xylylene and/or m-xylylene-modified phenolic resins; melamine-modified phenolic resins; terpene-modified phenolic resins; dicyclopentadiene-type naphthol resins; cyclopentadiene-modified phenolic resins; polycyclic aromatic ring-modified phenolic resins; and biphenyl-type phenolic resins. Among these, novolac-type phenolic resins are preferred, and cresol novolac resins are more preferred.

Examples of the acid anhydride curing agent include phthalic anhydride, 3-methyl-1,2,3,6-tetrahydrophthalic anhydride, 4-methyl-1,2,3,6-tetrahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, methyl-3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride, benzophenonetetracarboxylic dianhydride, and methyl himic acid.
Examples of the amine-based curing agent include chain aliphatic polyamines such as diethylenetriamine, triethylenetetraamine, and diethylaminopropylamine; cyclic aliphatic polyamines such as N-aminoethylpiperazine and isophoronediamine; aliphatic diamines having an aromatic ring such as m-xylylenediamine; aromatic amines such as m-phenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone; and guanylurea.
Examples of the cyanate resin curing agent include 2,2-bis(4-cyanatophenyl)propane, bis(4-cyanatophenyl)ethane, bis(3,5-dimethyl-4-cyanatophenyl)methane, 2,2-bis(4-cyanatophenyl)-1,1,1,3,3,3-hexafluoropropane, α,α'-bis(4-cyanatophenyl)-m-diisopropylbenzene, cyanate ester compounds of phenol-added dicyclopentadiene polymers, phenol novolac type cyanate ester compounds, and cresol novolac type cyanate ester compounds.

When the thermosetting resin composition contains the curing agent (B), the content is preferably 15 to 80 parts by mass, more preferably 25 to 70 parts by mass, and even more preferably 35 to 60 parts by mass, per 100 parts by mass of the resin component in the thermosetting resin composition.

When an epoxy resin is used as the (A) thermosetting resin, the equivalent ratio of the epoxy groups derived from the epoxy resin and the active hydrogen to the epoxy groups derived from the (B) curing agent (active hydrogen/epoxy group) is preferably 0.5 to 3, more preferably 0.7 to 2.5, and even more preferably 0.8 to 2.2.

((C) Curing Accelerator)
The curing accelerator (C) is not particularly limited, and any one that has been conventionally used as a curing accelerator for thermosetting resins can be appropriately selected and used.
The curing accelerator (C) may be used alone or in combination of two or more kinds.
Examples of the (C) curing accelerator include phosphorus compounds, imidazole compounds and derivatives thereof, tertiary amine compounds, and quaternary ammonium compounds. Among these, imidazole compounds and derivatives thereof are preferred from the viewpoint of curing reaction acceleration.

Imidazole compounds and derivatives thereof include 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1,2-dimethylimidazole, 2-ethyl-1-methylimidazole. , 1,2-diethylimidazole, 1-ethyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 4-ethyl-2-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2- Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4,5 -dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 2,4-diamino-6-[2'- Methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[ Imidazole compounds such as 2'-ethyl-4'-methylimidazolyl-(1')]ethyl-s-triazine; addition reaction products of the imidazole compound and trimellitic acid; addition reaction products of the imidazole compound and isocyanuric acid; Examples include an addition reaction product between the imidazole compound and hydrobromic acid; an addition reaction product between the imidazole compound and an epoxy resin.

When the thermosetting resin composition contains the curing accelerator (C), the content is preferably 0.01 to 2 parts by mass, more preferably 0.02 to 1.5 parts by mass, and even more preferably 0.04 to 1 part by mass, per 100 parts by mass of the resin components in the thermosetting resin composition.

((D) Inorganic filler)
The thermosetting resin composition preferably further contains (D) an inorganic filler from the viewpoint of low thermal expansion and the like.
(D) There are no particular limitations on the inorganic filler, and any filler can be appropriately selected and used from those conventionally used as inorganic fillers in thermosetting resin compositions.
(D) Inorganic fillers may be used alone or in combination of two or more.
(D) Inorganic fillers include silica, alumina, barium sulfate, talc, mica, kaolin, boehmite, beryllia, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, water Clays such as aluminum oxide, aluminum borate, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, zinc borate, zinc stannate, zinc oxide, titanium oxide, silicon carbide, silicon nitride, boron nitride, calcined clay, etc. , short glass fibers, glass powder, hollow glass beads, etc. Examples of the glass include E glass, T glass, and D glass. Among these, silica is preferred from the viewpoint of low thermal expansion.
Examples of silica include precipitated silica, which is produced by a wet method and has a high water content, and dry silica, which is produced by a dry method and contains almost no bound water. Examples of dry process silica include crushed silica, fumed silica, and fused silica (fused spherical silica) depending on the manufacturing method. Among these, fused silica is preferred from the viewpoint of low thermal expansion and high fluidity when filled into a resin.

The silica is preferably silica surface-treated with a silane coupling agent.
Examples of silane coupling agents include aminosilane coupling agents, epoxysilane coupling agents, phenylsilane coupling agents, alkylsilane coupling agents, alkenylsilane coupling agents, alkynylsilane coupling agents, and haloalkylsilanes. coupling agents, siloxane coupling agents, hydrosilane coupling agents, silazane coupling agents, alkoxysilane coupling agents, chlorosilane coupling agents, (meth)acrylic silane coupling agents, aminosilane coupling agents agent, isocyanurate silane coupling agent, ureido silane coupling agent, mercaptosilane coupling agent, sulfide silane coupling agent, isocyanate silane coupling agent, and the like.

The average particle diameter of the inorganic filler (D) is preferably 0.01 to 6 μm, more preferably 0.1 to 5 μm, even more preferably 0.5 to 4 μm, and particularly preferably 1 to 3 μm.
In addition, in this specification, the average particle diameter refers to the particle diameter at a point corresponding to 50% of the volume when a cumulative frequency distribution curve based on the particle diameter is obtained with the total volume of the particles as 100%. It can be measured using a particle size distribution measuring device using a scattering method.

When the thermosetting resin composition contains (D) an inorganic filler, the content is preferably 10 to 300 parts by mass, more preferably 50 to 250 parts by mass, even more preferably 100 to 220 parts by mass, and particularly preferably 130 to 200 parts by mass, per 100 parts by mass of the resin component in the thermosetting resin composition, from the viewpoints of low thermal expansion and moldability.

(Other ingredients)
The thermosetting resin composition may contain organic fillers, flame retardants, thermoplastic resins, ultraviolet absorbers, antioxidants, photopolymerization initiators, optical brighteners, and adhesive properties within a range that does not impede the effects of the present invention. It may also contain other components such as improvers.

(Organic solvent)
From the viewpoint of facilitating the production of a prepreg, the thermosetting resin composition may be in the form of a varnish containing an organic solvent (hereinafter also referred to as a "resin varnish").
Examples of the organic solvent include alcohol-based solvents such as methanol, ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as butyl acetate and propylene glycol monomethyl ether acetate; ether-based solvents such as tetrahydrofuran; aromatic solvents such as toluene, xylene, and mesitylene; nitrogen-containing solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; and sulfur-containing solvents such as dimethylsulfoxide. Among these, from the viewpoints of solubility and appearance after coating, ketone-based solvents are preferred, and methyl ethyl ketone is more preferred.
The organic solvent may be used alone or in combination of two or more kinds.
From the viewpoint of handleability, the solid content concentration in the resin varnish is preferably from 10 to 80 mass %, more preferably from 20 to 75 mass %, and even more preferably from 40 to 75 mass %.
In this specification, the term "solid content" refers to non-volatile content excluding volatile substances such as water and solvents contained in a thermosetting resin composition, and refers to components that remain without volatilization when the thermosetting resin composition is dried, and also includes liquid, starch syrup-like, and wax-like substances at room temperature around 25°C.

[Prepreg manufacturing method]
Next, the method for producing the prepreg of the present invention, which includes the above steps 1 to 3, will be described.

<Step 1>
Step 1 is a step of obtaining a prepreg precursor, the prepreg precursor is made by B-staging a thermosetting resin composition, and the B-staging is a step of obtaining a prepreg precursor using a thermosetting resin composition as a base material. After impregnation, heat treatment is performed.

Methods for impregnating the base material with the thermosetting resin composition include, but are not particularly limited to, a hot melt method, a solvent method, and the like.
The hot melt method is a method in which a base material is directly impregnated with a thermosetting resin composition whose viscosity has been reduced by heating. Examples include a method in which a resin film is formed and then laminated onto a base material, and a method in which a thermosetting resin composition is directly applied to a base material using a die coater or the like.
The solvent method is a method in which a base material is impregnated with a thermosetting resin composition in the form of a resin varnish, and includes, for example, a method in which the base material is immersed in a resin varnish and then dried.

Here, when the hot melt method is applied, the B-staging may be performed simultaneously with the heating when laminating the resin film to the substrate. That is, the resin film may be laminated to the substrate while being heated, and the heating may be continued to B-stage the thermosetting resin composition to obtain a prepreg precursor. In this case, the heating temperature during lamination and the heating temperature during B-staging may be the same or different.
In addition, when the solvent method is applied, the B-staging may be performed simultaneously with the heating for drying the resin varnish. That is, after the substrate is immersed in the resin varnish, the heating may be continued while drying the organic solvent by heating to B-stage the thermosetting resin composition to obtain a prepreg precursor. In this case, the heating temperature during the drying and the heating temperature during the B-staging may be the same or different.
The conditions of the heat treatment in this step are not particularly limited as long as the conditions are capable of bringing the thermosetting resin composition into the B-stage, and may be appropriately determined depending on the type of thermosetting resin, etc. The temperature of the heat treatment is, for example, 70 to 200°C, may be 80 to 150°C, or may be 90 to 130°C. The time of the heat treatment is, for example, 1 to 30 minutes, may be 2 to 25 minutes, or may be 3 to 20 minutes. When the hot melt method is applied, the conditions can be called lamination conditions, and when the solvent method is applied, the conditions can be called drying conditions.

<Step 2>
Step 2 is a step of cooling the prepreg precursor obtained in Step 1. That is, in Step 2, the prepreg precursor obtained by B-staging the thermosetting resin composition by heat treatment in Step 1 is cooled to a temperature lower than at least the temperature at which the heat treatment was performed. It is a process.
By carrying out this step, the thermosetting resin composition undergoes a thermal history of B-staging and cooling, which is generally applied when manufacturing prepreg, and the resulting prepreg precursor is There is inherent distortion, etc. that occurs in the prepreg and causes dimensional changes.
In this way, by incorporating the distortion caused by the thermal history of heating (Step 1) and cooling (Step 2) before Step 3, which will be described later, the above-mentioned distortion, etc. can be eliminated and dimensional changes can be made in Step 3. It becomes possible to effectively equalize the amount. Furthermore, whether or not the distortion caused by the thermal history of heating (process 1) and cooling (process 2), which was once eliminated in step 3, will not occur even if the same thermal history is applied after step 3, Even if it occurs, it will be very small, so the prepreg obtained by the present invention will have extremely small variation in the amount of dimensional change.

The prepreg precursor may be cooled by natural cooling or by using a cooling device such as a blower, a cooling roll, etc. The surface temperature of the prepreg precursor after cooling in this step is usually 5 to 80° C., preferably 8 to 50° C., more preferably 10 to 30° C., and even more preferably room temperature.
In this specification, room temperature refers to the ambient temperature without temperature control such as heating or cooling, and is generally about 15 to 25° C., but is not limited to the above range as it may vary depending on the weather, season, etc.

<Step 3>
Step 3 is a step of obtaining prepreg, and the prepreg is obtained by subjecting the prepreg precursor cooled in Step 2 to surface heat treatment, and the surface heat treatment increases the surface temperature of the prepreg precursor. This is the process of

The prepreg of the present invention becomes a prepreg with particularly small variation in the amount of dimensional change by carrying out step 3. The reason for this is not clear, but it is thought that this step eliminates the distortion of the base material in the prepreg precursor generated in steps 1, 2, etc., and reduces the dimensional change during curing due to the distortion, thereby making the amount of dimensional change uniform.
The heating method for the surface heating treatment in step 3 is not particularly limited, and examples thereof include a heating method using a panel heater, a heating method using hot air, a heating method using high frequency waves, a heating method using magnetic lines, a heating method using a laser, and a heating method that combines these.
The heating conditions for the surface heat treatment are not particularly limited as long as they are conditions that cause the surface temperature of the prepreg precursor to increase from the surface temperature before the surface heat treatment is performed and do not significantly affect the various properties (e.g., fluidity) of the resulting prepreg, and may be appropriately determined depending on the type of thermosetting resin, etc.
The increase in the surface temperature of the prepreg precursor due to the surface heat treatment (i.e., the absolute value of the difference between the surface temperature before the surface heat treatment and the maximum surface temperature reached during the surface heat treatment) is preferably 5 to 110°C, more preferably 20 to 90°C, and even more preferably 40 to 70°C, from the viewpoint of reducing variation in the amount of dimensional change while maintaining good moldability of the prepreg.
The heating temperature in the surface heat treatment is, from the viewpoint of reducing variation in the amount of dimensional change while maintaining good moldability of the prepreg, in the range of such a surface temperature of the prepreg precursor, for example, 20 to 130°C, preferably 40 to 110°C, and more preferably 60 to 90°C.
In addition, from the viewpoint of maintaining good productivity of the prepreg and from the viewpoint of maintaining the prepreg in a B-stage state and reducing the variation in the amount of dimensional change while maintaining good moldability, the surface heat treatment is preferably performed at a higher temperature and for a shorter time than the heating performed during the B-stage in step 1. From this viewpoint, the surface heat treatment is preferably performed in an environment of 200 to 700 ° C, more preferably in an environment of 250 to 600 ° C, and even more preferably in an environment of 350 to 550 ° C. As a specific example, when a heating method using a panel heater is performed, the heating setting temperature of the panel heater is preferably 200 to 700 ° C, more preferably 250 to 600 ° C, and even more preferably 350 to 550 ° C.
The heating time of the surface heat treatment is preferably 1.0 to 10.0 seconds, more preferably 1.5 to 6.0 seconds, and even more preferably 2.0 to 4.0 seconds, from the viewpoint of maintaining good prepreg productivity and from the viewpoint of maintaining the prepreg in a B-stage state and reducing variation in the amount of dimensional change while maintaining good moldability.

From the viewpoint of the handling and tackiness of the prepreg, it is preferable to subject the prepreg obtained in step 3 to a cooling step in which it is cooled. The prepreg may be cooled by natural cooling or by using a cooling device such as a blower or a cooling roll. The temperature of the prepreg after cooling is usually 5 to 80°C, preferably 8 to 50°C, more preferably 10 to 30°C, and even more preferably room temperature.

Note that Step 3 may be carried out in the manufacturing process of the metal-clad laminate of the present invention, which will be described later. Specifically, Step 3 may be performed with metal foils placed on both sides of the prepreg precursor obtained in Step 2, and then the prepreg and metal foil may be laminated and molded. The conditions for lamination molding are as described in the section regarding the laminate of the present invention, which will be described later.

The content of the thermosetting resin composition in the prepreg of the present invention, calculated as solid content, is preferably from 20 to 90 mass %, more preferably from 30 to 80 mass %, and even more preferably from 40 to 75 mass %.
The thickness of the prepreg of the present invention is, for example, 0.01 to 0.5 mm, and from the viewpoint of moldability and enabling high-density wiring, it is preferably 0.02 to 0.2 mm, and more preferably 0.03 to 0.1 mm.

The prepreg of the present invention obtained as described above has a standard deviation σ, determined according to the following method, of preferably 0.012% or less, more preferably 0.011% or less, even more preferably 0.010% or less, even more preferably 0.009% or less, and particularly preferably 0.008% or less. There is no particular restriction on the lower limit of the standard deviation σ, but it is usually 0.003% or more, and may be 0.005% or more, 0.006% or more, or 0.007% or more.
How to calculate standard deviation σ:
A copper foil having a thickness of 18 μm is laminated on both sides of one prepreg, and the laminate is heated and pressurized at 190° C. and 2.45 MPa for 90 minutes to produce a double-sided copper-clad laminate having a thickness of 0.1 mm. The double-sided copper-clad laminate thus obtained is subjected to drilling of holes having a diameter of 1.0 mm in the plane at positions 1 to 8 shown in FIG. 1. The distances of three points in each of the warp direction (1-7, 2-6, 3-5) and weft direction (1-3, 8-4, 7-5) shown in FIG. 1 are measured using an image measuring device, and each measured distance is taken as the initial value. Thereafter, the outer layer copper foil is removed, and the laminate is heated in a dryer at 185° C. for 60 minutes. After cooling, the distances of three points in each of the warp direction (1-7, 2-6, 3-5) and weft direction (1-3, 8-4, 7-5) are measured in the same manner as in the measurement method for the initial value. The average of the change rates of each measured distance from the initial value [(measured value after heat treatment-initial value) x 100/initial value] is calculated, and the standard deviation σ for the average is calculated.
The image measuring instrument is not particularly limited, but for example, a "QV-A808P1L-D" (manufactured by Mitutoyo Corporation) can be used.

[Laminated board]
The laminate of the present invention is formed by laminating and molding the prepreg of the present invention and metal foil.
The laminate of the present invention can be manufactured by, for example, using one sheet of the prepreg of the present invention or, if necessary, stacking 2 to 20 sheets and laminating the prepreg with metal foil arranged on one or both sides. can. Note that hereinafter, a laminate on which metal foil is arranged may be referred to as a metal-clad laminate.

There are no particular limitations on the metal of the metal foil, so long as it is used as an electrical insulating material.
From the viewpoint of electrical conductivity, the metal of the metal foil is preferably copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, or an alloy containing at least one of these metal elements, more preferably copper or amylumium, and even more preferably copper. That is, the laminate of the present invention is preferably a copper-clad laminate.
The thickness of the metal foil may be appropriately selected depending on the application of the printed wiring board, and is preferably 0.5 to 150 μm, more preferably 1 to 100 μm, further preferably 5 to 50 μm, and particularly preferably 5 to 30 μm.
Alternatively, the plating layer may be formed by plating the metal foil. The metal of the plating layer is not particularly limited as long as it is a metal that can be used for plating, but is preferably copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, or an alloy containing at least one of these metal elements.
The plating method is not particularly limited, and electrolytic plating, electroless plating, etc. can be used.

As the forming conditions for the laminate, known forming methods for electrically insulating material laminates and multilayer boards can be applied, such as using a multistage press, multistage vacuum press, continuous molding, autoclave molding machine, etc. Molding can be performed under the conditions of 100 to 250°C, pressure of 0.2 to 10 MPa, and heating time of 0.1 to 5 hours.
Moreover, a multilayer board can also be manufactured by combining the prepreg of the present invention and an inner layer printed wiring board and performing lamination molding.

[Printed wiring board]
The printed wiring board of the present invention comprises the prepreg of the present invention or the laminate of the present invention.
The printed wiring board of the present invention can be produced, for example, by subjecting the metal foil of the laminate of the present invention to circuit processing, which can be carried out, for example, by forming a resist pattern on the surface of the metal foil, removing unnecessary parts of the metal foil by etching, peeling off the resist pattern, forming necessary through holes by drilling or laser, forming a resist pattern again, plating to make the through holes conductive, and finally peeling off the resist pattern.
The above-mentioned metal-clad laminate is laminated on the surface of the printed wiring board obtained in this way under the same conditions as above, and then the circuit is processed in the same manner as above to obtain a multi-layer printed wiring board. In this case, it is not necessarily required to form a through hole, and a via hole may be formed, or both may be formed. Such multi-layering may be performed for the required number of sheets.

[Semiconductor package]
The semiconductor package of the present invention is made using the printed wiring board of the present invention.
The semiconductor package of the present invention can be manufactured by mounting a semiconductor chip, a memory, etc. at a predetermined position on the printed wiring board of the present invention.

Next, the present invention will be explained in more detail with reference to the following examples, but these examples are not intended to limit the present invention in any way. The performance of the prepreg etc. obtained in each example was evaluated based on the following evaluation method. Note that the room temperature in this example was 25°C.

[Evaluation method]
<1. Moldability
The four-layer copper-clad laminate prepared in each example was immersed in an etching solution to remove the outer copper layer to obtain an evaluation board, which was visually inspected for the presence or absence of voids and scratches within a surface area of 340 mm x 500 mm. Those in which no voids or scratches were found were rated as "no abnormality," and those in which voids or scratches were found were rated as "abnormality," and these were used as an index of formability.

<2. Variation in dimensional change＞
As shown in FIG. 1, a hole with a diameter of 1.0 mm was made in the plane of the double-sided copper-clad laminate produced in each example, to obtain an evaluation board shown in the schematic diagram of FIG.
Next, in Figure 1, the distances between holes in the "warp direction" (1-7, 2-6, 3-5) and the weft direction (1-3, 8-5) are determined. 4 distance and 7-5 distance) were measured using "QV-A808P1L-D" (manufactured by Mitutoyo Corporation), and each measured distance was used as an initial value. Next, the evaluation board was immersed in an etching solution to remove the outer layer copper foil, and then heated in a dryer at 185° C. for 60 minutes. After cooling, the distance between each hole was measured by the same method as the initial value, and this was taken as the measured value after the heat treatment.
For each hole distance, find the rate of change of the measured value after heat treatment with respect to the initial value ((initial value - measured value after heat treatment) x 100/(initial value)), and calculate the standard deviation σ for the average value. The standard deviation σ was calculated as the variation in the amount of dimensional change.

Example 1
(Preparation of prepreg precursor: Steps 1-2)
(A) As a thermosetting resin, 19 parts by mass of biphenylaralkyl novolac type epoxy resin (epoxy equivalent: 280 to 300 g/eq),
(B) 16 parts by mass of cresol novolac resin (hydroxyl equivalent: 119 g/eq) as a curing agent,
(C) 0.02 parts by mass of 2-ethyl-4-methylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd.) as a curing accelerator;
(D) As an inorganic filler, 65 parts by mass of spherical silica (average particle size: 2 μm) is mixed and diluted with a solvent (methyl ethyl ketone) to form a varnish-like thermosetting resin composition (solid content concentration: 70 parts by mass). %) was prepared.
This thermosetting resin composition is impregnated into a glass cloth (manufactured by Nittobo Co., Ltd., trade name: 1037 cloth, thickness: 0.025 mm), which is a base material, and then the thermosetting resin composition is It was heated in a drying oven at 100-200° C. for 5-15 minutes until staged. Thereafter, it was cooled to room temperature by natural cooling to obtain a prepreg precursor.

(Preparation of prepreg: step 3)
The prepreg precursor obtained above was subjected to a surface heating treatment using a panel heater at a heating setting temperature of 500°C for a heating time of 3 seconds so that the surface temperature of the prepreg precursor reached 70°C, and then cooled to room temperature to obtain a prepreg.
The content of the thermosetting resin composition in the obtained prepreg was 70 mass % in terms of solid content.

(Preparation of copper-clad laminate)
One sheet of the prepreg obtained above was used to laminate 18 μm copper foil “YGP-18” (manufactured by Nippon Denkai Co., Ltd.) on both sides, and heated and pressurized for 90 minutes at a temperature of 190° C. and a pressure of 25 kgf/cm ² (2.45 MPa) to produce a double-sided copper-clad laminate for one prepreg.
Both copper foil surfaces of the obtained double-sided copper-clad laminate were subjected to an inner layer adhesion treatment (using "BF treatment liquid" (manufactured by Hitachi Chemical Co., Ltd.)), and one prepreg was stacked on each side with 18 μm copper foil "YGP-18" (manufactured by Nippon Denkai Co., Ltd.) on both sides. The laminate was then heated and pressurized at a temperature of 190°C and a pressure of 25 kgf/ ^cm2 (2.45 MPa) for 90 minutes to produce a four-layer copper-clad laminate.
Separately, 18 μm copper foil “3EC-VLP-18” (manufactured by Mitsui Kinzoku Co., Ltd.) was laminated on both sides of one prepreg, and heated and pressurized at a temperature of 190° C. and a pressure of 25 kgf/cm ² (2.45 MPa) for 90 minutes to produce a double-sided copper-clad laminate for one prepreg.

Example 2
(Preparation of prepreg precursor: Steps 1-2)
Component (A): A solution of the maleimide compound (A) produced in Production Example 1 below was used.
[Manufacture example 1]
In a 1 L reaction vessel equipped with a thermometer, a stirrer, and a moisture meter with a reflux condenser, 19.2 g of 4,4'-diaminodiphenylmethane, 174.0 g of bis(4-maleimidophenyl)methane, and p-aminophenol were added. 6.6g and 330.0g of dimethylacetamide were added and reacted at 100°C for 2 hours to form a dimethylacetamide solution of maleimide compound (A) (Mw = 1,370) having an acidic substituent and an N-substituted maleimide group. It was used as component (A).
In addition, the said weight average molecular weight (Mw) was converted from the calibration curve using standard polystyrene by gel permeation chromatography (GPC). The calibration curve is standard polystyrene: TSK standard POLYSTYRENE (Type; A-2500, A-5000, F-1, F-2, F-4, F-10, F-20, F-40) [manufactured by Tosoh Corporation] It was approximated by a cubic equation using . The conditions for GPC are shown below.
Equipment: (Pump: L-6200 type [manufactured by Hitachi High-Technologies Corporation]),
(Detector: L-3300 type RI [manufactured by Hitachi High-Technologies Corporation]),
(Column oven: L-655A-52 [manufactured by Hitachi High-Technologies Corporation])
Column: TSKgel SuperHZ2000+TSKgel SuperHZ2300 (all manufactured by Tosoh Corporation)
Column size: 6.0mm x 40mm (guard column), 7.8mm x 300mm (column)
Eluent: Tetrahydrofuran Sample concentration: 20mg/5mL
Injection volume: 10μL
Flow rate: 0.5mL/min Measurement temperature: 40℃

(A) As a thermosetting resin, 45 parts by mass of the maleimide compound (A) obtained above, and 30 parts by mass of a cresol novolac type epoxy resin,
As component (B), 2 parts by mass of dicyandiamide (manufactured by Nippon Carbide Industries Co., Ltd.),
As component (D), 50 parts by mass of fused silica (average particle diameter: 1.9 μm, specific surface area 5.8 m ² /g) treated with an aminosilane coupling agent,
As a thermoplastic resin, 25 parts by mass of a copolymer resin of styrene and maleic anhydride (styrene/maleic anhydride = 4, Mw = 11,000),
As a flame retardant, 2.0 parts by mass of aromatic phosphate ester in terms of phosphorus atom,
(However, in the case of a solution, the solid content equivalent amount is shown.) Then, methyl ethyl ketone was added so that the solid content concentration of the solution was 65 to 75% by mass to prepare a resin varnish.
Glass cloth (0.1 mm) of IPC standard #3313 was impregnated with each of the obtained resin varnishes, dried for 4 minutes with a panel heater set at a temperature of 160°C (Step 1), and then allowed to cool to room temperature (Step 2). ), a prepreg precursor was obtained.

(Preparation of prepreg: step 3)
The prepreg precursor obtained above was subjected to a surface heating treatment using a panel heater at a heating setting temperature of 500°C for a heating time of 3 seconds so that the surface temperature of the prepreg precursor reached 70°C, and then cooled to room temperature to obtain a prepreg.
The content of the thermosetting resin composition in the obtained prepreg was 70 mass % in terms of solid content.

(Preparation of copper-clad laminate)
A four-layer copper-clad laminate and a double-sided copper-clad laminate were produced in the same manner as in Example 1 using one sheet of the prepreg obtained above.

[Comparative example 1]
In Example 1, a prepreg, a four-layer copper-clad laminate, and a double-sided copper-clad laminate were produced in the same manner as in Example 1, except that Step 3 was not performed.

[Comparative example 2]
In Example 2, a prepreg, a four-layer copper-clad laminate, and a double-sided copper-clad laminate were produced in the same manner as in Example 1, except that Step 3 was not performed.

The evaluation results of the four-layer copper-clad laminate and double-sided copper-clad laminate obtained in each of the above examples are shown in Table 1.

In terms of moldability, the prepregs of Examples 1 and 2 had good resin embedding properties, and no abnormalities such as scratches or voids were observed in the laminates obtained from these prepregs. In addition, the prepregs of Examples 1 and 2 tended to have smaller variations in dimensional change (standard deviation (σ)) than the prepregs of Comparative Examples 1 and 2, which were not subjected to surface heat treatment.

The prepreg of the present invention has excellent moldability and small variation in dimensional change, making it useful as a highly integrated semiconductor package, printed wiring board for electronic devices, etc.

Claims (10)

A prepreg manufacturing method comprising the following steps 1 to 3.
Step 1: A step of obtaining a prepreg precursor, the prepreg precursor is made by B-staging a thermosetting resin composition, and the B-staging involves impregnating a base material with the thermosetting resin composition. After that, heat treatment is performed, and the thermosetting resin composition contains (D) an inorganic filler in an amount of 50 to 300 parts by mass based on 100 parts by mass of the resin component in the thermosetting resin composition. Contains part .
Step 2: A step of cooling the prepreg precursor obtained in Step 1.
Step 3: A step of obtaining prepreg, the prepreg is obtained by subjecting the prepreg precursor cooled in Step 2 to surface heat treatment, and the surface heat treatment increases the surface temperature of the prepreg precursor. The heating time of the surface heating treatment is 1.0 to 6.0 seconds . 2. The prepreg manufacturing method according to claim 1, wherein the surface heat treatment in step 3 is a treatment for increasing the surface temperature of the prepreg precursor by 5 to 110°C. The prepreg manufacturing method according to claim 1 or 2, wherein the surface heating treatment in step 3 is a treatment of heating the surface temperature of the prepreg precursor to 20 to 130°C. The prepreg manufacturing method according to any one of claims 1 to 3, wherein the surface heat treatment in step 3 is a treatment in which the prepreg precursor is heated in an environment of 200 to 700°C. 5. The prepreg manufacturing method according to claim 4, wherein the surface heat treatment in step 3 is a treatment in which the prepreg precursor is heated in an environment of 350 to 700°C. The method for producing a prepreg according to any one of claims 1 to 5 , wherein the heating time of the surface heat treatment in step 3 is 1.0 to 4.0 seconds. The method for producing a prepreg according to any one of claims 1 to 6 , wherein the base material is glass cloth. A method for producing a laminate, comprising laminating and molding a prepreg produced by the method for producing a prepreg according to any one of claims 1 to 7 and a metal foil. A method for producing a printed wiring board using a prepreg produced by the method for producing a prepreg according to any one of claims 1 to 7 or a laminate produced by the method for producing a laminate according to claim 8 . A method for manufacturing a semiconductor package using a printed wiring board manufactured by the method for manufacturing a printed wiring board according to claim 9 .