JP6623632B2 - Insulating resin film and multilayer printed wiring board - Google Patents

Description

  The present invention relates to an insulating resin film and a multilayer printed wiring board.

A printed wiring board, which is one of the structures having a conductive circuit, has a plurality of wiring layers formed on a core substrate, and a copper-clad laminate serving as a core substrate and an interlayer insulating layer provided between each wiring layer. And a solder resist provided on the outermost surface. A semiconductor element is usually mounted on a printed wiring board via a die bonding material or an underfill material. If necessary, the entire surface may be sealed with a transfer sealing material, or a metal cap (lid) for improving heat dissipation may be attached.
2. Description of the Related Art In recent years, lightening, thinning and miniaturization of semiconductor devices have been unavoidable, and the density of semiconductor elements and multilayer printed wiring boards has been further increased. In addition, mounting forms such as package-on-package, in which a semiconductor device is stacked on a semiconductor device, are also being actively performed, and it is expected that the mounting density of the semiconductor device will be further increased in the future.

  Here, a conventional method for manufacturing a multilayer printed wiring board is shown in FIG. The multilayer printed wiring board 100 shown in FIG. 1F has a wiring pattern on the surface and inside. The multilayer printed wiring board 100 is obtained by laminating a copper-clad laminate, an interlayer insulating material, a metal foil, and the like, and appropriately forming a wiring pattern by an etching method or a semi-additive method.

  First, an interlayer insulating layer 103 is formed on both surfaces of a copper-clad laminate 101 having a wiring pattern 102 on the surface (see FIG. 1A). The interlayer insulating layer 103 may be printed with a thermosetting resin composition using a screen printer or a roll coater, or a film made of the thermosetting resin composition is prepared in advance, and the film is formed using a laminator. Can be attached to the surface of the printed wiring board. Next, an opening 104 is formed in a portion that needs to be electrically connected to the outside by using a YAG laser or a carbon dioxide laser, and smear (residue) around the opening 104 is removed by desmear treatment (FIG. 1B). reference). Next, a seed layer 105 is formed by an electroless plating method (see FIG. 1C). A photosensitive resin composition is laminated on the seed layer 105, and a predetermined portion is exposed and developed to form a pattern 106 of the photosensitive resin layer (see FIG. 1D). Next, a wiring pattern 107 is formed by an electrolytic plating method, and after the cured product of the photosensitive resin composition is removed by peeling liquid, the seed layer 105 is removed by etching (see FIG. 1E). By repeating the above and forming the solder resist 108 on the outermost surface, the multilayer printed wiring board 100 can be manufactured (see FIG. 1F). In the multilayer printed wiring board 100 thus obtained, a semiconductor element is mounted at a corresponding portion, and electrical connection can be ensured.

Incidentally, it is necessary to provide a via (opening) for electrically connecting the upper and lower wiring layers in the interlayer insulating layer of the multilayer printed wiring board. If the number of pins of the flip chip mounted on the multilayer printed wiring board increases, it is necessary to provide an opening corresponding to the number of pins. Conventional multilayer printed wiring boards have a low mounting density, and the number of pins on the semiconductor element to be mounted is designed to be in the range of thousands to 10,000 pins. There was no. However, as the miniaturization of semiconductor elements progresses and the number of pins increases from tens of thousands of pins to hundreds of thousands of pins, the openings formed in the interlayer insulating layer of the multilayer printed wiring board also become narrower in accordance with the number of pins of the semiconductor elements. There is a growing need to convert.
Hitherto, development of a multilayer printed wiring board in which an opening is provided by a laser in an interlayer insulating layer using a thermosetting resin composition has been advanced (for example, see Patent Documents 1 to 4). However, the multilayer printed wiring board 100 manufactured by the method shown in FIG. 1 requires the introduction of new equipment such as a laser, and it is difficult to provide a relatively large opening or a minute opening of 60 μm or less. In addition, there are problems such as that it is necessary to use different lasers according to the aperture diameter, and it is difficult to provide a special shape. In addition, when forming an opening using a laser, since each opening must be formed one by one, it takes time when a large number of fine openings need to be provided, and there is a residue of resin around the opening. Therefore, there is also a problem that the reliability of the obtained multilayer printed wiring board is reduced unless the residue is removed.
In order to solve the above-mentioned problem, a method using a photosensitive resin composition has been proposed as a method for providing an opening without using a laser (for example, see Patent Document 5).

JP 08-279678 A JP-A-11-054913 JP 2001-217543 A JP-A-2003-017848 WO 2013/054790

Since the method described in Patent Document 5 includes a step of exposing the photosensitive resin layer from the thermosetting resin layer after the lamination of the insulating resin film, and a step of removing the exposed photosensitive resin layer. In addition, as compared with the roughening process used in the conventional wiring board process, the amount of reduction in the thickness of the insulating layer is increased. Therefore, when a conventional insulating resin film is used, as the amount of reduction in film thickness increases, the inorganic filler in the film is exposed and / or falls off, so that the surface roughness increases, and as a result, the adhesive strength to the conductor layer increases. And fine wiring becomes difficult. Therefore, when using a method of reducing the content of the inorganic filler in the thermosetting resin layer to reduce the surface roughness and improve the adhesive strength with the conductor layer, the thermal expansion coefficient of the insulating resin film is reduced. Therefore, it has been difficult to cope with the thinning of the substrate.
Therefore, an object of the present invention is to provide an insulating resin film that exhibits high adhesive strength to a conductor layer with low surface roughness while having a low coefficient of thermal expansion, and to provide a multilayer printed wiring board containing the insulating resin film. is there.

  The present inventors have conducted intensive studies to solve the above problems, and as a result, a first layer having a specific range of the content of the inorganic filler and a second layer having a specific range of the content of the inorganic filler. It has been found that the above-mentioned problems can be solved by using an insulating resin film having the above on the first layer, and the present invention has been completed. The present invention has been completed based on such findings.

The present invention relates to the following [1] to [10].
[1] A thermosetting resin composition (1) containing (A1) a thermosetting resin, (B1) a curing agent, (C1) a curing accelerator, and (D1) an inorganic filler. (A2) a first layer containing the thermosetting resin composition (1) in which the content of the inorganic filler (D1) is 1 to 40% by mass based on the solid content of the curable resin composition (1); A) a thermosetting resin composition comprising a thermosetting resin, (B2) a curing agent, (C2) a curing accelerator, and (D2) an inorganic filler; Forming a second layer on the first layer containing the thermosetting resin composition (2) in which the content of the inorganic filler (D2) with respect to the solid content of (2) is 50 to 80% by mass; An insulating resin film.
[2] The total thickness of the first layer and the second layer is 10 to 100 μm, and the ratio of the thickness of the first layer is 10 to 10% of the total thickness of the first layer and the second layer. The insulating resin film according to the above [1], which is 80%.
[3] The insulating resin film according to the above [1] or [2], wherein the (A1) thermosetting resin is an epoxy resin.
[4] The inorganic filler (D1) and the inorganic filler (D2) are each independently silica, alumina, barium sulfate, talc, mica, kaolin, boehmite, beryllia, barium titanate, potassium titanate, strontium titanate , Calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum borate, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, zinc borate, zinc stannate, zinc oxide, titanium oxide, carbonized The insulating resin film according to any one of the above [1] to [3], which is at least one selected from the group consisting of silicon, silicon nitride, boron nitride, clay, short glass fiber, glass powder, and hollow glass beads. .
[5] The insulating resin film according to any one of [1] to [4], wherein the volume average particle diameters of the (D1) inorganic filler and the (D2) inorganic filler are each 0.01 to 3 μm. .
[6] The insulation according to any one of [1] to [5], wherein the (D1) inorganic filler and the (D2) inorganic filler are both inorganic fillers surface-treated with a silane coupling agent. Resin film.
[7] The insulating resin film according to any one of [1] to [6], wherein the first layer has a support on a surface not having the second layer.
[8] An insulating resin film containing (A) a thermosetting resin, (B) a curing agent, (C) a curing accelerator, and (D) an inorganic filler, wherein the insulating resin film has a thickness in the thickness direction. When the lower part is the lower part from the center and the upper part is the upper part from the center, the content of the (D) inorganic filler in the lower layer is 1 to 40% by mass, and the content of the (D) inorganic filler in the upper layer Is 50 to 80% by mass.
[9] The insulating resin film according to the above [8], having a support on a lower layer side surface.
[10] A multilayer printed wiring board containing the insulating resin film according to any one of [1] to [9].

  According to the present invention, it is possible to obtain an insulating resin film exhibiting a low thermal expansion coefficient and a low surface roughness and exhibiting high adhesive strength to a conductor layer, and a multilayer printed wiring board containing the insulating resin film.

It is a schematic diagram which shows the manufacturing method of the conventional multilayer printed wiring board.

Hereinafter, the present invention will be described in detail.
[Insulating resin film]
The insulating resin film of the present invention is a thermosetting resin composition (1) containing (A1) a thermosetting resin, (B1) a curing agent, (C1) a curing accelerator, and (D1) an inorganic filler. In addition, the first containing the thermosetting resin composition (1) in which the content of the inorganic filler (D1) is 1 to 40% by mass based on the solid content of the thermosetting resin composition (1). A thermosetting resin composition (2) comprising: (A2) a thermosetting resin; (B2) a curing agent; (C2) a curing accelerator; and (D2) an inorganic filler. The second layer containing the thermosetting resin composition (2) in which the content of the inorganic filler (D2) is 50 to 80% by mass based on the solid content of the curable resin composition (2) is the first layer. An insulating resin film formed on a layer.
Each component of the thermosetting resin composition (1) and the thermosetting resin composition (2) may be the same or different. From the viewpoint of the adhesion between the first layer and the second layer, (A1) the thermosetting resin in the thermosetting resin composition (1) and (A2) in the thermosetting resin composition (2). The thermosetting resins are preferably the same. From the same viewpoint, each component in the thermosetting resin composition (1) and each component in the thermosetting resin composition (2) are preferably the same.
Thermosetting resin, curing agent, curing accelerator and inorganic filler in thermosetting resin composition (1), and thermosetting resin, curing agent, curing acceleration in thermosetting resin composition (2) The agent and the inorganic filler will be described below in order.

(Thermosetting resin)
As the thermosetting resin, for example, epoxy resin, phenol resin, unsaturated imide resin, cyanate resin, isocyanate resin, benzoxazine resin, oxetane resin, amino resin, unsaturated polyester resin, allyl resin, dicyclopentadiene resin, silicone Resins, triazine resins and melamine resins. Further, the present invention is not particularly limited thereto, and a known thermosetting resin can be used. These may be used alone or in combination of two or more.
Among these, epoxy resins are preferred in terms of excellent moldability and electrical insulation.
The epoxy equivalent of the epoxy resin is preferably 100 to 500 g / eq, more preferably 150 to 400 g / eq, and further preferably 200 to 350 g / eq. Here, the epoxy equivalent is the mass (g / eq) of the resin per epoxy group, and can be measured according to the method specified in JIS K7236. Specifically, using an automatic titrator “GT-200” (manufactured by Mitsubishi Chemical Analytech Co., Ltd.), weigh 2 g of the epoxy resin in a 200 ml beaker, drop 90 ml of methyl ethyl ketone, dissolve in the ultrasonic cleaner, It is determined by adding 10 ml of glacial acetic acid and 1.5 g of cetyltrimethylammonium bromide, and titrating with a 0.1 mol / L perchloric acid / acetic acid solution.

As the epoxy resin, an epoxy resin having two or more epoxy groups in one molecule is preferable. Here, the epoxy resin is classified into a glycidyl ether type epoxy resin, a glycidylamine type epoxy resin, a glycidyl ester type epoxy resin, and the like. Among these, a glycidyl ether type epoxy resin is preferable.
Examples of the resin having two epoxy groups in one molecule include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin and bisphenol S type epoxy resin; alicyclic epoxy resin; Epoxy resin.
Alternatively, a polyfunctional epoxy resin having an average of more than two epoxy groups in the molecule may be used. Examples of the polyfunctional epoxy resin include novolak epoxy resins such as phenol aralkyl novolak epoxy resin, biphenyl aralkyl novolak epoxy resin (above, aralkyl novolak epoxy resin), phenol novolak epoxy resin, and cresol novolak epoxy resin. Is mentioned. In particular, an aralkyl novolak type epoxy resin is preferable, and a biphenyl aralkyl novolak type epoxy resin is more preferable, from the viewpoint of adhesive strength to a conductor layer and insulation reliability. The biphenyl aralkyl novolak epoxy resin refers to an aralkyl novolac epoxy resin containing an aromatic ring of a biphenyl derivative in one molecule.
One epoxy resin may be used alone, or two or more epoxy resins may be used in combination.

As the epoxy resin, an epoxy resin represented by the following formula (1) is also preferable.

(In the formula, p represents 1 to 5.)
p is preferably 1.2 to 5, more preferably 1.4 to 3.

  Examples of commercially available biphenylaralkyl novolak type epoxy resins include “NC-3000” (an epoxy resin with p = 1.7 in the above formula (1), epoxy equivalent = 275 g / eq), and “NC-3000H” (the above formula ( In 1), an epoxy resin with p = 2.8, epoxy equivalent = 290 g / eq) [all manufactured by Nippon Kayaku Co., Ltd.].

(Curing agent)
The curing agent is not particularly limited as long as it can cure the thermosetting resin, and a known curing agent can be used.
For example, as a curing agent for an epoxy resin, a phenol resin, an acid anhydride, an amine, a hydrazide compound, dicyandiamide, a cyanate resin, and the like can be given. Among these, a phenol resin is preferable from the viewpoint of insulation reliability.
The phenol resin is not particularly limited as long as it has two or more phenolic hydroxyl groups in one molecule. For example, compounds having two phenolic hydroxyl groups in one molecule such as resorcin, catechol, bisphenol A, bisphenol F and substituted or unsubstituted biphenol; aralkyl-type phenolic resins; dicyclopentadiene-type phenolic resins; triphenylmethane-type Phenol resin; Novolak phenol resin such as phenol novolak resin, cresol novolak resin, aminotriazine-modified novolak phenol resin; resol phenol resin; copolymer phenol resin of benzaldehyde phenol and aralkyl phenol; p-xylylene and / or Or m-xylylene-modified phenolic resin; melamine-modified phenolic resin; terpene-modified phenolic resin; dicyclopentadiene-type naphthol resin; Nord resin; polycyclic aromatic ring-modified phenolic resins; and biphenyl type phenolic resins. The phenol resins may be used alone or in combination of two or more. Among these, from the viewpoint of insulation reliability, a novolak-type phenol resin is preferable, a phenol novolak resin, an aminotriazine-modified novolak-type phenol resin is more preferable, and it is further possible to use a phenol novolak resin and an aminotriazine-modified novolak-type phenol resin together. preferable.
Examples of the acid anhydride include phthalic anhydride, 3-methyl-1,2,3,6-tetrahydrophthalic anhydride, 4-methyl-1,2,3,6-tetrahydrophthalic anhydride, 3-methylhexa Hydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, methyl-3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride, benzophenonetetracarboxylic dianhydride, methylhymic acid, etc. No. As the acid anhydride, one type may be used alone, or two or more types may be used in combination.

Examples of the amine include linear aliphatic polyamines such as diethylenetriamine, triethylenetetraamine, and diethylaminopropylamine; cyclic aliphatic polyamines such as N-aminoethylpiperazine and isophoronediamine; and aliphatic aromatic diamines such as m-xylylenediamine Aromatic amines such as m-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone; and guanylurea. One type of amine may be used alone, or two or more types may be used in combination.
Examples of the hydrazide compound include adipic dihydrazide, sebacic dihydrazide, dodecandiohydrazide, isophthalic dihydrazide, salicylic dihydrazide and the like. One hydrazide compound may be used alone, or two or more hydrazide compounds may be used in combination.

  Examples of the cyanate resin 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, phenol-added dicyclopentadiene Polymeric cyanate ester compounds, phenol novolak-type cyanate ester compounds, cresol novolak-type cyanate ester compounds, and the like. One type of cyanate resin may be used alone, or two or more types may be used in combination.

(Curing accelerator)
Examples of the curing accelerator, particularly a curing accelerator for an epoxy resin, include a phosphorus compound; an imidazole compound and a derivative thereof; a tertiary amine compound; and a quaternary ammonium compound. When an epoxy resin is used as the thermosetting resin, a phosphorus compound is preferred from the viewpoint of accelerating the curing reaction.
Examples of the phosphorus-based compound include triphenylphosphine, diphenyl (alkylphenyl) phosphine, tris (alkylphenyl) phosphine, tris (alkoxyphenyl) phosphine, tris (alkylalkoxyphenyl) phosphine, tris (dialkylphenyl) phosphine, tris ( Triarylphosphines such as trialkylphenyl) phosphine, tris (tetraalkylphenyl) phosphine, tris (dialkoxyphenyl) phosphine, tris (trialkoxyphenyl) phosphine, and tris (tetraalkoxyphenyl) phosphine; trialkylphosphines, dialkylarylphosphines Phosphines, such as alkyldiarylphosphines; complexes of such organic phosphines with organic borons; Such adducts of emissions based compounds.

  Specific examples of the imidazole compound and its derivative include, for example, 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- , 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 compounds with trimellitic acid; addition reactions of the imidazole compounds with isocyanuric acid Products: an addition reaction product of the imidazole compound with hydrobromic acid; an addition reaction product of the imidazole compound with an epoxy resin. One imidazole compound may be used alone, or two or more imidazole compounds may be used in combination.

As the tertiary amine, for example, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, diethylisopropylamine, benzyldimethylamine, N, N-dimethylaniline and N, N, N ′, N'-tetramethylethylenediamine and the like can be mentioned. As the tertiary amine, one type may be used alone, or two or more types may be used in combination.
Examples of the quaternary ammonium salt include tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrahexylammonium bromide, and benzyltrimethylammonium chloride. As the quaternary ammonium salt, one type may be used alone, or two or more types may be used in combination.

(Inorganic filler)
Examples of the inorganic filler include silica, alumina, barium sulfate, talc, mica, kaolin, boehmite, beryllia, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, and hydroxide. Clays such as aluminum, 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, Examples thereof include short glass fibers, glass powder, and hollow glass beads, and at least one selected from the group consisting of these is preferably used. Preferred examples of the glass include E glass, T glass, and D glass. Among these, silica is preferred from the viewpoint of reducing the coefficient of thermal expansion of the insulating resin layer.
Examples of the silica include precipitated silica produced by a wet method and having a high water content, and dry silica produced by a dry method and containing almost no bound water. Dry silica further includes crushed silica, fumed silica, and fused silica (fused spherical silica) depending on the production method. Silica used for the inorganic filler is preferably fused silica from the viewpoint of low thermal expansion and high fluidity when filled into a resin.

The silica is preferably silica that has been surface-treated with a silane coupling agent. When silica that has been surface-treated with a silane coupling agent is used, the adhesive force between silica and the resin component is improved, the falling off of silica is suppressed, and the surface roughness tends to decrease.
Examples of the silane coupling agent include an aminosilane-based coupling agent, an epoxysilane-based coupling agent, a phenylsilane-based coupling agent, an alkylsilane-based coupling agent, an alkenylsilane-based coupling agent, and an alkynylsilane-based coupling agent. , Haloalkylsilane coupling agent, siloxane coupling agent, hydrosilane coupling agent, silazane coupling agent, alkoxysilane coupling agent, chlorosilane coupling agent, (meth) acrylsilane coupling agent, aminosilane Coupling agent, isocyanurate silane coupling agent, ureido silane coupling agent, mercapto silane coupling agent, sulfide silane coupling agent and isocyanate silane coupling Etc. The. Among these, alkenyl silane coupling agents are preferred, and vinyl silane coupling agents are more preferred.

The average particle diameter of the inorganic filler is preferably from 0.01 to 3 μm, more preferably from 0.01 to 1 μm, and still more preferably from 0.1 to 1 μm. In particular, when silica is used as the inorganic filler, the average particle size of the silica is preferably in the above range.
By setting the average particle diameter of the inorganic filler in the above range, the surface roughness of the insulating layer tends to be reduced while maintaining good film formability.
The average particle diameter is a particle diameter at a point corresponding to exactly 50% by volume when a cumulative frequency distribution curve based on the particle diameter is determined with the total volume of the particles being 100%. Can be measured by a particle size distribution measuring device or the like.

(Other components)
Both the thermosetting resin composition (1) and the thermosetting resin composition (2) may further contain other components.
Other components include, for example, an organic filler, a flame retardant, a thermoplastic resin, an ultraviolet absorber, an antioxidant, a photopolymerization initiator, a fluorescent brightener, and an adhesion improver.
Examples of the organic filler include resin particles made of polyethylene, polypropylene, polystyrene, polyphenylene ether resin, silicone resin, tetrafluoroethylene resin, and the like; acrylate resin, methacrylate resin, conjugated diene resin, and the like. A so-called core-shell resin particle having a core layer in a rubber state and a shell layer in a glass state made of an acrylate resin, a methacrylate resin, an aromatic vinyl resin, a vinyl cyanide resin, or the like. No.
Examples of the flame retardant include a halogen-based flame retardant containing bromine and / or chlorine; a phosphorus-based flame retardant such as triphenyl phosphate, tricresyl phosphate, trisdichloropropyl phosphate, a phosphoric ester compound, or red phosphorus; Nitrogen-based flame retardants such as guanidine acid, melamine sulfate, melamine polyphosphate, and melamine cyanurate; and phosphazene-based flame retardants such as cyclophosphazene and polyphosphazene.
Examples of the thermoplastic resin include polyphenylene ether resin, phenoxy resin, polycarbonate resin, polyester resin, polyamide resin, polyimide resin, polyamideimide resin, xylene resin, petroleum resin, and silicone resin.
Examples of the ultraviolet absorber include a benzotriazole-based ultraviolet absorber. Examples of the antioxidant include a hindered phenol antioxidant and a hindered amine antioxidant. Examples of the photopolymerization initiator include benzophenones, benzylketals, and thioxanthone-based photopolymerization initiators. Examples of the fluorescent whitening agent include a fluorescent whitening agent of a stilbene derivative. Examples of the adhesion improver include urea compounds such as urea silane; coupling agents such as silane coupling agents, titanate coupling agents, and aluminate coupling agents.

(Content ratio of each component in the thermosetting resin composition)
In the thermosetting resin composition (1), the content of the inorganic filler (D1) is 1 to 40% by mass based on the solid content of the thermosetting resin composition (1). On the other hand, in the thermosetting resin composition (2), the content of the inorganic filler (D2) is 50 to 80% by mass based on the solid content of the thermosetting resin composition (2). When the content of the inorganic filler (D1) and the content of the inorganic filler (D2) are in the above ranges, respectively, the insulating resin film which has a low coefficient of thermal expansion and a low surface roughness and which exhibits high adhesive strength to the conductor layer can be obtained. Tend to be obtained.
(D1) The content of the inorganic filler is preferably from 10 to 40% by mass, more preferably from 20 to 40% by mass, and still more preferably from 30 to 40% by mass, based on the solid content of the thermosetting resin composition (1). %. The content of (D2) the inorganic filler is preferably 55 to 75% by mass, more preferably 60 to 75% by mass, and still more preferably 60 to 75% by mass, based on the solid content of the thermosetting resin composition (2). ７０70% by mass.
The numerical range of the content of the inorganic filler (D1) and the numerical range of the content of the inorganic filler (D2) can be arbitrarily combined.

If the content of (D1) the inorganic filler and the content of (D2) the inorganic filler are within the above range, the content of the other components is not particularly limited, and may be appropriately selected within the range of common knowledge of those skilled in the art. Can be.
For example, the content of the (A1) thermosetting resin in the thermosetting resin composition (1) is preferably 20 with respect to the solid content (including the inorganic filler) of the thermosetting resin composition (1). ６５65 mass%, more preferably 30-65 mass%, further preferably 40-60 mass%. The content of the thermosetting resin (A2) in the thermosetting resin composition (2) is preferably 15 to 50 with respect to the solid content (including the inorganic filler) of the thermosetting resin composition (2). %, More preferably 15 to 40% by mass, even more preferably 20 to 30% by mass.
Moreover, the content of the (C1) curing accelerator in the thermosetting resin composition (1) is preferably 0.1 to 5% by mass, more preferably the content of the (A1) thermosetting resin. It is 0.5 to 5% by mass, more preferably 1 to 5% by mass. Similarly, the content of the (C2) curing accelerator in the thermosetting resin composition (2) is preferably 0.1 to 5% by mass, more preferably the content of the (A2) thermosetting resin. Is 0.5 to 5% by mass, more preferably 1 to 5% by mass.

(Organic solvent)
The thermosetting resin composition (1) and the thermosetting resin composition (2) may contain an organic solvent from the viewpoint of facilitating handling by dilution and facilitating formation of an insulating resin film. Good. In this specification, a thermosetting resin composition containing an organic solvent may be referred to as a resin varnish. The organic solvent may be used in a state of being mixed with the above components, or may be used arbitrarily separately from the above components.
Examples of the organic solvent include, but are not particularly limited to, alcohol solvents such as methanol, ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Ester solvents such as butyl acetate and propylene glycol monomethyl ether acetate; ether solvents such as tetrahydrofuran; aromatic solvents such as toluene, xylene and mesitylene; solvents containing nitrogen atoms such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone. A sulfur atom-containing solvent such as dimethyl sulfoxide.
Among these, from the viewpoint of solubility and appearance after coating, ketone solvents, nitrogen atom-containing solvents, or a mixed solvent thereof are preferable, and acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, dimethylformamide, dimethylacetamide, N- Methyl pyrrolidone is more preferred. Further, a mixed solvent of acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone and dimethylformamide, dimethylacetamide or N-methylpyrrolidone is more preferable.
One organic solvent may be used alone, or two or more organic solvents may be used in combination.
The content of the organic solvent in the thermosetting resin composition (1) and the content of the organic solvent in the thermosetting resin composition (2) are all determined from the viewpoint of stabilizing the film thickness at the time of application and improving the appearance. (The concentration of the components other than the organic solvent) is preferably 10 to 80% by mass, more preferably 20 to 75% by mass, further preferably 40 to 75% by mass, and particularly preferably 50 to 70% by mass.

[Thickness of each layer]
As described above, the insulating resin film of the present invention is obtained by forming the first layer and the second layer on the first layer.
In the insulating resin film of the present invention, the total thickness of the first layer and the second layer is preferably 10 to 100 μm, and the ratio of the thickness of the first layer is the total thickness of the first layer and the second layer. The insulating resin film is preferably 10 to 80% of the film thickness. The total thickness of the first layer and the second layer is more preferably 10 to 70 μm, further preferably 10 to 50 μm, particularly preferably 15 to 40 μm, and most preferably 15 to 35 μm. Further, the ratio of the thickness of the first layer to the total thickness of the first layer and the second layer is more preferably 20 to 80%, further preferably 30 to 70%, and particularly preferably 40 to 60%. %. The numerical range of the total thickness of the first layer and the second layer and the numerical range of the ratio of the thickness of the first layer can be arbitrarily combined.
Here, the film thickness indicates the film thickness of the insulating resin film obtained by drying (drying conditions will be described later).

(Support)
In the first layer of the insulating resin film of the present invention, a support may be provided on a surface having no second layer. In this case, the support, the first layer, and the second layer have a configuration of “support / first layer / second layer”.
Examples of the support include organic films such as polyethylene film, polyvinyl chloride film, polyethylene terephthalate (PET) film, polyethylene naphthalate film, and polyimide film; and metal foils such as copper foil and aluminum foil. An organic film with a release layer and a metal foil with a release layer can also be used.
From the viewpoint of easy release of the support, cost, and handleability, an organic film with a release layer is preferable, and a PET film with a release layer is more preferable. Examples of commercially available PET films with a release layer include “Unipeel (registered trademark) TR-1” (manufactured by Unitika), “Therapy (registered trademark)” (manufactured by Toray Film Processing Co., Ltd.), and the like. .

  In addition, a protective film can be laminated on the insulating resin film of the present invention. The protective film is mainly used for the purpose of preventing foreign substances from adhering to the insulating resin film of the present invention and preventing scratches. The protective film is peeled off before lamination or hot pressing. The same material as the support may be used as the protective film. Although the thickness of the protective film is not particularly limited, it is usually preferably 1 to 40 μm.

[Production method of insulating resin film]
The method for producing the insulating resin film of the present invention is not particularly limited, but includes the following two production methods.
Production method 1: After applying the thermosetting resin composition (1) for the first layer on the support, and then applying the thermosetting resin composition (2) for the second layer on the first layer , Through a drying step.
Production method 2: After applying the thermosetting resin composition (1) for the first layer on the support and passing through a drying step, the thermosetting resin composition (2) for the second layer is applied to the first layer. A method of applying on top and passing through a drying process.
Among the production methods 1 and 2, the production method 1 is preferable from the viewpoint of mass productivity.

As a condition of the drying step, in any case, a condition of drying at a temperature of 60 to 180 ° C. for 30 to 600 seconds is preferable. More preferably, the temperature is from 70 to 140C.
The method for applying the thermosetting resin compositions (1) and (2) is not particularly limited, and a known method can be used. For example, coating can be performed using a coating apparatus such as a reverse coater, a gravure coater, an air doctor coater, a die coater, and a lip coater.

One embodiment of the insulating resin film of the present invention includes the following embodiments.
An insulating resin film containing (A) a thermosetting resin, (B) a curing agent, (C) a curing accelerator, and (D) an inorganic filler, and is downward from the center in the thickness direction of the insulating resin film. Is the lower layer, and the upper layer from the center is the upper layer, the content of the (D) inorganic filler in the lower layer is 1 to 40% by mass, and the content of the (D) inorganic filler in the upper layer is 50 to 50%. 80% by mass of an insulating resin film.
The insulating resin film is an embodiment that can be adopted when the (A1) thermosetting resin and the (A2) thermosetting resin are the same. That is, when the boundary between the first layer and the second layer is unclear, the first layer and the second layer are apparently one layer. Since the existing ratio of the inorganic filler is different between the upper and lower portions, the aspect is shown.
The content of the inorganic filler (D) in the lower layer is preferably 10 to 40% by mass, more preferably 20 to 40% by mass, and further preferably 30 to 40% by mass. Further, the content of the inorganic filler (D) in the upper layer is preferably 55 to 75% by mass, more preferably 60 to 75% by mass, and further preferably 60 to 70% by mass.
Note that a support may be provided on the lower layer side surface of the insulating resin film. In this case, the insulating resin film has a configuration of “support / (lower layer / upper layer)”.

[Multilayer printed wiring board and manufacturing method thereof]
The present invention also provides a multilayer printed wiring board containing the insulating resin film.
The method for producing the multilayer printed wiring board of the present invention is not particularly limited. For example, it can be produced by a production method having the following steps (a) to (f).
Step (a): a step of laminating a photosensitive resin composition on an inner layer substrate on which a conductor circuit has been formed to form a photosensitive resin composition layer (hereinafter, also referred to as a photosensitive resin layer forming step (a)).
Step (b): a step of subjecting the photosensitive resin layer to exposure and development to form a pattern (hereinafter, also referred to as a photosensitive resin layer pattern (post) forming step (b)).
Step (c): a step of laminating the insulating resin film of the present invention on the inner layer substrate so as to cover the posts and forming an insulating layer (hereinafter, also referred to as an insulating layer forming step (c)).
Step (d): a step of exposing the post by removing a part of the insulating layer (hereinafter also referred to as a cueing step (d)).
Step (e): a step of removing the post and exposing the conductive circuit of the inner layer substrate (hereinafter, also referred to as an opening forming step (e)).
Step (f): a step of forming a conductive circuit in the insulating layer and the opening (hereinafter, also referred to as a conductive circuit forming step (f)).

(Photosensitive resin layer forming step (a))
In the photosensitive resin layer forming step (a), the method of forming the photosensitive resin composition layer on the inner layer substrate on which the conductor circuit has been formed is not particularly limited. A method of stacking the photosensitive resin films so that the carrier is on the outside is simple and preferable. The method of laminating the photosensitive resin film with a carrier on the inner layer substrate can be carried out using a device such as a vacuum laminator or a hot roll laminator, for example, at a temperature of 100 to 130 ° C. and a pressure of 0.3 to 0.5 MPa.
The photosensitive resin composition is not particularly limited, and a known photosensitive resin composition can be used.

(Photosensitive resin layer pattern (post) forming step (b))
In the photosensitive resin layer pattern (post) forming step (b), for example, a photo tool having a design in which circular patterns having a diameter of 60 μm or less (for example, 30 μm) are arranged at a pitch of 100 μm on a carrier is arranged. After the exposure from above, the carrier is removed, and the unexposed portion is removed using a 1% by mass aqueous solution of sodium carbonate or the like.
Exposure conditions are appropriately determined depending on the photosensitive resin composition used. For example, as a light source of an actinic ray, a carbon arc lamp, a mercury vapor arc lamp, a high-pressure mercury lamp, a xenon lamp, a gas laser such as an argon laser, a solid-state laser such as a YAG laser, a semiconductor laser, or the like, an ultraviolet ray, a visible light, etc. This is performed using a material that emits light. As a wavelength (exposure wavelength) of the actinic ray, for example, 340 to 430 nm is used.

(Insulating layer forming step (c))
Examples of an apparatus used for forming an insulating layer on the inner layer substrate include a vacuum laminator, a hot roll laminator, and a vacuum press. Among these, it is preferable to use a vacuum laminator from the viewpoint of moldability and mass productivity. For example, it is preferable to use a vacuum laminator to pressurize at a temperature of 60 to 140 ° C. and a pressure of 0.2 to 1 MPa for 20 to 60 seconds. As the vacuum laminator, for example, "MVLP500-600" (manufactured by Meiki Seisakusho) or the like is used.
The substrate on which the insulating layer is formed may be subjected to a heat treatment as needed. As a method of the heat treatment, for example, a method of heating at a temperature of 140 to 190 ° C. for 15 to 120 minutes using a dryer can be mentioned.

(Cueing step (d))
In the cueing step (d), in order to remove a part of the insulating layer, for example, a polishing treatment using a ceramic roll, a sand blast treatment, a desmear treatment, a wet blast treatment, a plasma treatment, or the like used in a conventional wiring board process is used. be able to. Among these, it is preferable to use plasma treatment from the viewpoint of surface smoothness and mass productivity.
The conditions for the plasma treatment are not particularly limited as long as the posts can be exposed. For example, using a plasma apparatus “Plasma Asher PB-1000S” (manufactured by Mori Engineering Co., Ltd.), a pressure of 300 to 500 Pa and an RF power of 300 to 500 W with an introduced gas of 10 to 20% of oxygen gas and 2 to 8% of argon gas. For 5 to 20 minutes.

(Opening forming step (e))
In the opening forming step (e), as a method used for removing the post, for example, a processing method using a known plating resist stripping solution used for wiring formation, and a known desmear used in a printed wiring board manufacturing process A treatment method using a liquid or the like can be used. It is preferable to use a desmear liquid from the viewpoint of mass productivity and adhesion between the insulating layer and a conductor circuit described later. As the desmear liquid, a desmear liquid containing a permanganate aqueous solution is preferable.
As the desmear liquid, a commercially available desmear stock solution may be used, and for example, “Concentrate Compact CP” (manufactured by Atotech) or the like can be used.

(Conductor circuit forming step (f))
In the conductor circuit forming step (f), as a method of forming a conductor circuit in the insulating layer and the opening, a known conductor circuit forming method in a printed wiring board manufacturing step can be used. For example, a conventional semi-additive process can be used. As a conductor layer forming method in the semi-additive process, a sputtering method, electroless plating, CVD (Chemical Vapor Deposition), or the like can be used. From the viewpoint of cost and mass productivity, the formation of the conductor layer is preferably performed by electroless plating. As the electroless plating solution, a commercially available one can be used. For example, an electroless copper plating solution manufactured by Atotech Co. is used.

  Next, the present invention will be described in more detail with reference to the following examples, but these examples do not limit the present invention in any way. In addition, using the insulating resin film or the evaluation substrate manufactured in each example, the thermal expansion coefficient, the surface roughness, and the adhesive strength with the conductor layer were measured according to the following methods.

[1. Measurement method of thermal expansion coefficient]
The insulating resin films produced in each example were overlapped so that the PET film was on the outside, and were bonded together at 80 ° C. and 0.5 MPa using a vacuum laminator. Next, one side of the PET film was removed, and the PET film was laminated on the glossy surface of the copper foil “YGP-12” (manufactured by Nippon Denshi Co., Ltd.) so that the PET film was on the outside, and laminated. Next, after removing the carrier film and curing at 180 ° C. for 90 minutes, the copper foil was removed by etching treatment to produce a cured product film having a thickness of 50 μm. The manufactured cured product film was cut into a size of 30 mm in length and 4 mm in width, and the thermal expansion coefficient (linear expansion coefficient) was measured using a thermal analysis system “EXSTAR6000” (manufactured by SII Nanotechnology Co., Ltd.). In addition, in order to remove the influence of the thermal strain of the sample, the heating-cooling cycle was repeated twice, and the thermal expansion coefficient [ppm / ° C] of 50 ° C to 120 ° C in the second temperature displacement chart was measured. It was an index of low thermal expansion. The smaller the value, the better the low thermal expansion.
Measurement conditions 1 ^st Run: room temperature → 210 ° C. (heating rate 10 ° C. / min)
^{2 nd Run: 0 ℃ → 270} ℃ ( heating rate 10 ° C. / min)

[2. Method for measuring surface roughness (Ra)]
The conductor layer of the evaluation substrate obtained in each example was removed by etching treatment, and the surface roughness (Ra) of the exposed resin surface was measured under the following measurement conditions using a surface shape measuring device “WykoNT9100” (manufactured by Veeco). Measured.
-Measurement conditions-
Internal lens: 1x External lens: 50x Measurement range: 0.120 x 0.095mm
Measurement depth: 10 μm
Measurement method: Vertical scanning interference method (VSI method)

[3. Method for measuring adhesive strength]
A portion having a width of 10 mm and a length of 100 mm was formed by immersing a part of the circuit layer of the evaluation substrate obtained in each example in a copper etching solution “ammonium persulfate (APS)” (manufactured by Mitsubishi Gas Chemical Company). . Using an autograph “AG-100C” (manufactured by Shimadzu Corporation), peel off one end at the interface between the circuit layer and the resin, hold it with a gripper, and peel off at room temperature in a vertical direction at a pulling speed of about 50 mm / min. The load (kN / m) was measured.

(Preparation Example 1) Preparation of thermosetting resin composition (1) Biphenylaralkyl novolak type epoxy resin "NC3000" (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 275 g / eq, formula (1)) as component (A1) 25.0 g of methyl ethyl ketone was added to 50.0 g of p = 1.7). Then, 4.1 g of a phenol novolak resin “Phenolite (registered trademark) TD-2131” (manufactured by DIC Corporation, hydroxyl equivalent: 104 g / eq) as a component (B1) and an aminotriazine-modified novolak type phenol resin “Phenolite (registered) (Trademark) LA3018-50P "(manufactured by DIC Corporation), and 0.15 g of a triphenylphosphine 1.4-benzoquinone adduct" P2 "(manufactured by Hokko Chemical Industry Co., Ltd.) as a component (C1). After that, the resultant was diluted with methyl ethyl ketone. To this, 44.5 g of a silica slurry “SC2050KNK” (manufactured by Admatechs Co., Ltd., 70% by mass) was added as the component (D1), and the mixture was mixed using a dispersing machine “Nanomizer” (manufactured by Yoshida Kikai Kogyo Co., Ltd.), followed by thermosetting. Resin composition (1) (solid content concentration: about 60% by mass, inorganic filler content in solid content: 31.4% by mass) was obtained.

(Preparation Example 2) Preparation of thermosetting resin composition (2) As component (A2), biphenylaralkyl type epoxy resin "NC3000" (Nippon Kayaku Co., Ltd., epoxy equivalent 275 g / eq, p in formula (1)) = 1.7) 25.0 g of methyl ethyl ketone was added to 50.0 g. To this, 4.1 g of phenol novolak resin “Phenolite (registered trademark) TD-2131” (manufactured by DIC Corporation, hydroxyl equivalent 104 g / eq) as a component (B2) and aminotriazine-modified novolak type phenol resin “Phenolite (registered) (Trademark) LA3018-50P "(manufactured by DIC Corporation) in an amount of 27.4 g, and 0.15 g of a triphenylphosphine 1.4-benzoquinone adduct" P2 "(manufactured by Hokuko Chemical Industry Co., Ltd.) was further added as a component (C2). Thereafter, the resultant was diluted with methyl ethyl ketone. (D2) 177.9 g of a silica slurry “SC2050KNK” (manufactured by Admatechs, 70% by mass) was added as a component, and the mixture was mixed using a dispersing machine “Nanomizer” (manufactured by Yoshida Kikai Kogyo Co., Ltd.) to obtain a thermosetting resin composition. A product (2) (solid content concentration: about 60% by mass, inorganic filler content in the solid content: 64.7% by mass) was obtained.

(Preparation Example 3) Preparation of thermosetting resin composition (3) Biphenylaralkyl type epoxy resin "NC3000" (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 275 g / eq, p in formula (1)) as component (A1) = 1.7) 25.0 g of methyl ethyl ketone was added to 50.0 g. Then, 4.1 g of a phenol novolak resin “Phenolite (registered trademark) TD-2131” (manufactured by DIC Corporation, hydroxyl equivalent: 104 g / eq) as a component (B1) and an aminotriazine-modified novolak type phenol resin “Phenolite (registered) (Trademark) LA3018-50P "(manufactured by DIC Corporation), and 0.15 g of a triphenylphosphine 1.4-benzoquinone adduct" P2 "(manufactured by Hokko Chemical Industry Co., Ltd.) as a component (C1). After that, the resultant was diluted with methyl ethyl ketone. To this, 91.6 g of a silica slurry “SC2050KNK” (manufactured by Admatechs, 70% by mass) was added as a component (D1), and the mixture was mixed using a dispersing machine “Nanomizer” (manufactured by Yoshida Kikai Kogyo Co., Ltd.), followed by thermosetting. Resin composition (3) (solids concentration: about 60% by mass, content of inorganic filler in solids: 48.6% by mass) was obtained.

(Example 1)
The thermosetting resin composition (1) for a first layer obtained in Preparation Example 1 was placed on a PET film with a release agent “Unipiel (registered trademark) TR-1” (manufactured by Unitika Ltd.) as a support. The composition is applied with a bar coater (manufactured by Daiichi Rika Co., Ltd.), and the thermosetting resin composition (2) for the second layer obtained in Preparation Example 2 is applied to the applicator “YBA-6” type (Yoshimitsu Seiki Co., Ltd.) Co., Ltd.), dried at 80 ° C. for 5 minutes using a drier, and dried to a thickness of 12 μm for the first layer and 13 μm for the second layer. (Total content of inorganic filler: 48.7% by mass).
Using the obtained insulating resin film 1, a substrate for evaluation was manufactured as follows.

<Manufacture of evaluation substrate>
First, a copper-clad laminate “MCL-E-679FG” (manufactured by Hitachi Chemical Co., Ltd.) having a copper foil having a thickness of 12 μm adhered to both surfaces was prepared. The thickness of the copper-clad laminate was 400 μm. This copper surface was roughened with a CZ treatment liquid “Mech Etch Bond (registered trademark) CZ-8100” (manufactured by Meck Co., Ltd.) to produce an inner layer substrate.
Next, the insulating resin film 1 was superimposed on the inner layer substrate so that the PET film was on the outside, and laminated using a vacuum laminator under the conditions of 80 ° C. and 0.5 MPa (corresponding to the insulating layer forming step (c)). ). Thereafter, the PET film was removed, and the substrate was heated at 160 ° C. for 30 minutes using a dryer to produce a substrate with an insulating layer.
-Plating method-
Using a plasma asher PB-1000S (manufactured by Mori Engineering Co., Ltd.), the insulating layer surface of the obtained substrate with an insulating layer was subjected to an introduced gas of 16% oxygen gas and 5% argon gas at a pressure of 400 Pa and an RF power of 400 W. The plasma treatment was performed for 10 minutes (corresponding to the cueing step (d)).
Next, as a swelling solution, a mixed solution of 500 mL of Swelling Dip Securigant P (manufactured by Atotech), 3 g of sodium hydroxide, and 500 mL of pure water was heated to 80 ° C., and the substrate with an insulating layer was immersed in this for 5 minutes. Was. Next, after washing the substrate with the insulating layer with water, as a roughening solution (desmear solution), a mixed solution of 640 mL of concentrate compact CP (manufactured by Atotech), 40 g of sodium hydroxide and 360 mL of pure water was heated to 80 ° C. The substrate with an insulating layer was immersed in this for 10 minutes (corresponding to the opening forming step (e)). Subsequently, as a neutralizing solution, a mixed solution of 200 mL / L of Reduction Solution Securigant P500 (manufactured by Atotech), 100 mL of 98% sulfuric acid and 700 mL of pure water was heated to 40 ° C., and the substrate with an insulating layer was added thereto for 5 minutes. It was immersed.
Next, after washing the substrate with an insulating layer with water, as a pretreatment for electroless plating, a mixed solution of 40 mL of cleaner Securigant 902 (manufactured by Atotech) and 960 mL of pure water as a conditioner solution is heated to 60 ° C. The substrate was immersed for 5 minutes, and then the substrate with an insulating layer was washed with water. Then, as a pre-dipping step, a mixed solution of 20 mL of Predip Neogant B (manufactured by Atotech), 1 mL of 98% sulfuric acid, and 979 mL of pure water was added at 25 ° C. For 1 minute. Next, as a catalyst applying step, the catalyst was immersed in a mixed solution of 40 mL of Activator Neogant 834 Conc (manufactured by Atotech), 4 g of sodium hydroxide, 5 g of boric acid, and 960 mL of pure water at 35 ° C. for 5 minutes. After washing the substrate with water, as a reduction step, a substrate with an insulating layer was placed in a mixed solution of 5 mL of Reducer Neogant WA (manufactured by Atotech), 100 mL of reducer accelerator 810 mod (manufactured by Atotech), and 895 mL of pure water at 30 ° C. for 1 minute, Was immersed. After washing the substrate with the insulating layer with water, finally as an electroless copper plating step, 80 mL of Basic Solution Print Gant MSK-DK (made by Atotech), 40 mL of Copper Solution Print Gant MSK-DK (made by Atotech) and stabilizer print Gant MSK- A substrate with an insulating layer is immersed in a mixture of 3 mL of DK (manufactured by Atotech), 14 mL of reducer Cu (manufactured by Atotech) and 853 mL of pure water at 28 ° C. for 15 minutes to form a copper plating film having a thickness of about 0.5 μm. Formed. After washing the substrate with an insulating layer with water, the obtained substrate with an insulating layer was dried at 80 ° C. for 15 minutes using a drier, and further subjected to copper sulfate electrolytic plating. Thereafter, annealing was performed at 170 ° C. for 30 minutes to form a conductor layer having a thickness of 30 μm on the surface of the insulating layer (corresponding to the conductor circuit forming step (f)), and the evaluation substrate 1 was obtained.
Using the insulating resin film 1 or the evaluation substrate 1, the coefficient of thermal expansion, the surface roughness, and the adhesive strength with the conductor layer were measured in accordance with the above-described methods. Table 1 shows the results.

(Comparative Example 1)
The thermosetting resin composition (1) obtained in Preparation Example 1 was coated on a PET film with a release agent “Unipeel (registered trademark) TR-1” (manufactured by Unitika Ltd.) as a support, using a bar coater (No. 1). It was applied at 80 ° C. for 5 minutes using a drier to obtain an insulating resin film 2 having a thickness of 25 μm (content of inorganic filler: 31.4% by mass).
An evaluation substrate 2 was manufactured in the same manner as in Example 1 using the obtained insulating resin film 2.
Using the insulating resin film 2 or the evaluation substrate 2, the coefficient of thermal expansion, the surface roughness, and the adhesive strength with the conductor layer were measured in accordance with the above-described methods. Table 1 shows the results.

(Comparative Example 2)
The thermosetting resin composition (3) produced in Preparation Example 3 was coated on a PET film with a release agent “Unipiel (registered trademark) TR-1” (manufactured by Unitika Ltd.) as a support, using a bar coater (No. 1). The product was applied with a drier and dried at 80 ° C. for 5 minutes using a drier to obtain a 25 μm-thick insulating resin film 3 (content of inorganic filler: 48.6% by mass).
An evaluation substrate 3 was manufactured in the same manner as in Example 1 using the obtained insulating resin film 3.
Using the insulating resin film 3 or the evaluation substrate 3, the coefficient of thermal expansion, the surface roughness, and the adhesive strength with the conductor layer were measured in accordance with the above-described methods. Table 1 shows the results.

From Example 1 in Table 1, it was confirmed that the insulating resin film having the configuration of the present invention had a low coefficient of thermal expansion, a low surface roughness, and a high adhesive strength to the conductor layer.
On the other hand, from Comparative Example 1, it was confirmed that when a single-layer insulating resin film having a small content of the inorganic filler was used, the adhesive strength was the same as that of Example 1, but the coefficient of thermal expansion was large. Further, as shown in Comparative Example 2, when the insulating resin film containing the same amount of the inorganic filler as in Example 1 was used in a single layer, the surface roughness was larger than in Example 1, and the adhesive strength was higher. Was significantly reduced.

  INDUSTRIAL APPLICABILITY The insulating resin film of the present invention has a low coefficient of thermal expansion while having a low surface roughness and a high adhesive strength to a conductor layer.

Claims (9)

(A1) biphenyl aralkyl novolak type epoxy resin as a thermosetting resin, (B1) a curing agent, meet (C1) curing accelerator and (D1) a thermosetting resin composition containing the inorganic filler (1) The first layer containing the thermosetting resin composition (1) in which the content of the inorganic filler (D1) is 20 to 40% by mass based on the solid content of the thermosetting resin composition (1) and (A2) biphenyl aralkyl novolak type epoxy resin as a thermosetting resin, (B2) a curing agent, (C2) a curing accelerator and (D2) comprising an inorganic filler thermosetting resin composition (2) Wherein the content of the inorganic filler (D2) with respect to the solid content of the thermosetting resin composition (2) is 60 to 80% by mass, and the thermosetting resin composition (2) contains Two layers are formed on the first layer, the first layer And an insulating resin film having a total thickness of the second layer of 15 to 35 μm.   The insulating resin film according to claim 1, wherein the ratio of the thickness of the first layer is 10 to 80% with respect to the total thickness of the first layer and the second layer. The inorganic filler (D1) and the inorganic filler (D2) are each independently silica, alumina, barium sulfate, talc, mica, kaolin, boehmite, beryllia, barium titanate, potassium titanate, strontium titanate, titanate Calcium, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum borate, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, zinc borate, zinc stannate, zinc oxide, titanium oxide, silicon carbide, nitrided The insulating resin film according to claim 1 , wherein the insulating resin film is at least one selected from the group consisting of silicon, boron nitride, clay, short glass fiber, glass powder, and hollow glass beads. The insulating resin film according to any one of claims 1 to 3 , wherein each of the (D1) inorganic filler and the (D2) inorganic filler has a volume average particle diameter of 0.01 to 3 µm. The insulating resin film according to any one of claims 1 to 4 , wherein (D1) the inorganic filler and (D2) the inorganic filler are both inorganic fillers surface-treated with a silane coupling agent. The insulating resin film according to any one of claims 1 to 5 , wherein the first layer has a support on a surface having no second layer. (A) a biphenyl aralkyl novolak type epoxy resin as a thermosetting resin, (B) a curing agent, an insulating resin film containing the curing accelerator (C) and (D) an inorganic filler, the insulating resin film When the lower part is the lower layer from the center in the thickness direction and the upper part is the upper part from the center, the content of the (D) inorganic filler in the lower layer is 20 to 40% by mass, and the (D) inorganic filler in the upper layer is An insulating resin film having a material content of 60 to 80% by mass and a film thickness of 15 to 35 μm. The insulating resin film according to claim 7 , having a support on a lower layer side surface. Multilayer printed wiring board containing an insulating resin film according to any one of claims 1-8.